Tuesday, September 28, 2021

09-27-2021-2349 - Attic

An attic (sometimes referred to as a loft) is a space found directly below the pitched roof of a house or other building; an attic may also be called a sky parlor^[1] or a garret. Because attics fill the space between the ceiling of the top floor of a building and the slanted roof, they are known for being awkwardly shaped spaces with exposed rafters and difficult-to-reach corners.

While some attics are converted into bedrooms, home offices, or attic apartments complete with windows and staircases, most remain difficult to access (and are usually entered using a loft hatch and ladder). Attics help control temperatures in a house by providing a large mass of slowly moving air, and are often used for storage. The hot air rising from the lower floors of a building is often retained in attics, further compounding their reputation as inhospitable environments. However, in recent years attics have been insulated to help decrease heating costs, since, on average, uninsulated attics account for 15 percent of the total energy loss in average houses.^[2]

A loft is also the uppermost space in a building but is distinguished from an attic in that an attic typically constitutes an entire floor of the building, while a loft covers only a few rooms, leaving one or more sides open to the lower floor.^{[citation needed]}

Attic bedroom in Skógar, Iceland.

^{https://en.wikipedia.org/wiki/Attic}

^{Pyroxferroite (Fe²⁺,Ca)SiO₃ is a single chain inosilicate. It is mostly composed of iron, silicon and oxygen, with smaller fractions of calcium and several other metals.^[1] Together with armalcolite and tranquillityite, it is one of the three minerals which were discovered on the Moon. It was then found in Lunar and Martian meteorites as well as a mineral in the Earth's crust. Pyroxferroite can also be produced by annealing synthetic clinopyroxene at high pressures and temperatures. The mineral is metastable and gradually decomposes at ambient conditions, but this process can take billions of years.}

Pyroxferroite

^{https://en.wikipedia.org/wiki/Pyroxferroite}

A fusion energy gain factor, usually expressed with the symbol Q, is the ratio of fusion power produced in a nuclear fusion reactor to the power required to maintain the plasma in steady state. The condition of Q = 1, when the power being released by the fusion reactions is equal to the required heating power, is referred to as breakeven, or in some sources, scientific breakeven.

The energy given off by the fusion reactions may be captured within the fuel, leading to self-heating. Most fusion reactions release at least some of their energy in a form that cannot be captured within the plasma, so a system at Q = 1 will cool without external heating. With typical fuels, self-heating in fusion reactors is not expected to match the external sources until at least Q = 5. If Q increases past this point, increasing self-heating eventually removes the need for external heating. At this point the reaction becomes self-sustaining, a condition called ignition. Ignition corresponds to infinite Q, and is generally regarded as highly desirable for practical reactor designs.

Over time, several related terms have entered the fusion lexicon. Energy that is not captured within the fuel can be captured externally to produce electricity. That electricity can be used to heat the plasma to operational temperatures. A system that is self-powered in this way is referred to as running at engineering breakeven. Operating above engineering breakeven, a machine would produce more electricity than it uses and could sell that excess. One that sells enough electricity to cover its operating costs is sometimes known as economic breakeven. Additionally, fusion fuels, especially tritium, are very expensive, so many experiments run on various test gasses like hydrogen or deuterium. A reactor running on these fuels that reaches the conditions for breakeven if tritium was introduced is said to be operating at extrapolated breakeven.

As of 2021, the record for Q is held by the JET tokamak in the UK, at Q = (16 MW)/(24 MW) ≈ 0.67, first attained in 1997. The highest record for extrapolated breakeven was posted by the JT-60 device, with Q_ext = 1.25, slightly besting JET's earlier 1.14. ITER was originally designed to reach ignition, but is currently designed to reach Q = 10, producing 500 MW of fusion power from 50 MW of injected thermal power.

In the case of neutrons carrying most of the practical energy, as is the case in the D-T fuel, this neutron energy is normally captured in a "blanket" of lithium that produces more tritium that is used to fuel the reactor. Due to various exothermic and endothermic reactions, the blanket may have a power gain factor M_R. M_R is typically on the order of 1.1 to 1.3, meaning it produces a small amount of energy as well. The net result, the total amount of energy released to the environment and thus available for energy production, is referred to as P_R, the net power output of the reactor.^[9]

The blanket is then cooled and the cooling fluid used in a heat exchanger driving conventional steam turbines and generators. That electricity is then fed back into the heating system.^[9] Each of these steps in the generation chain has an efficiency to consider. In the case of the plasma heating systems, $\eta _{heat}$ is on the order of 60 to 70%, while modern generator systems based on the Rankine cycle have $\eta _{elec}$ around 35 to 40%. Combining these we get a net efficiency of the power conversion loop as a whole, $\eta _{NPC}$ , of around 0.20 to 0.25. That is, about 20 to 25% of $P_{R}$ can be recirculated.^[9]

Thus, the fusion energy gain factor required to reach engineering breakeven is defined as:^[10]

$Q_{E}\equiv {\frac {P_{fus}}{P_{heat}}}={\frac {1}{\eta _{heat}\cdot f_{recirc}\cdot \eta _{elec}\cdot (1-f_{ch})}}$

To understand how $Q_{E}$ is used, consider a reactor operating at 20 MW and Q = 2. Q = 2 at 20 MW implies that P_heat is 10 MW. Of that original 20 MW about 20% is alphas, so assuming complete capture, 4 MW of P_heat is self-supplied. We need a total of 10 MW of heating and get 4 of that through alphas, so we need another 6 MW of power. Of the original 20 MW of output, 4 MW are left in the fuel, so we have 16 MW of net output. Using M_R of 1.15 for the blanket, we get P_R about 18.4 MW. Assuming a good $\eta _{NPC}$ of 0.25, that requires 24 MW P_R, so a reactor at Q = 2 cannot reach engineering breakeven. At Q = 4 one needs 5 MW of heating, 4 of which come from the fusion, leaving 1 MW of external power required, which can easily be generated by the 18.4 MW net output. Thus for this theoretical design the Q_E is between 2 and 4.

Considering real-world losses and efficiencies, Q values between 5 and 8 are typically listed for magnetic confinement devices,^[9] while inertial devices have dramatically lower values for $\eta _{heat}$ and thus require much higher Q_E values, on the order of 50 to 100.^[11]

Ignition[edit]

As the temperature of the plasma increases, the rate of fusion reactions grows rapidly, and with it, the rate of self-heating. In contrast, non-capturable energy losses like x-rays do not grow at the same rate. Thus, in overall terms, the self-heating process becomes more efficient as the temperature increases, and less energy is needed from external sources to keep it hot.

Eventually P_heat reaches zero, that is, all of the energy needed to keep the plasma at the operational temperature is being supplied by self-heating, and the amount of external energy that needs to be added drops to zero. This point is known as ignition. In the case of D-T fuel, where only 20% of the energy is released as alphas that give rise to self-heating, this cannot occur until the plasma is releasing at least five times the power needed to keep it at its working temperature.

Ignition, by definition, corresponds to an infinite Q, but it does not mean that f_recirc drops to zero as the other power sinks in the system, like the magnets and cooling systems, still need to be powered. Generally, however, these are much smaller than the energy in the heaters, and require a much smaller f_recirc. More importantly, this number is more likely to be near-constant, meaning that further improvements in plasma performance will result in more energy that can be directly used for commercial generation, as opposed to recirculation.

https://en.wikipedia.org/wiki/Fusion_energy_gain_factor

A field-reversed configuration (FRC) is a type of plasma device studied as a means of producing nuclear fusion. It confines a plasma on closed magnetic field lines without a central penetration.^[1]In an FRC, the plasma has the form of a self-stable torus, similar to a smoke ring.

FRCs are closely related to another self-stable magnetic confinement fusion device, the spheromak. Both are considered part of the compact toroid class of fusion devices. FRCs normally have a plasma that is more elongated than spheromaks, having the overall shape of a hollowed out sausage rather than the roughly spherical spheromak.

FRCs were a major area of research in the 1960s and into the 1970s, but had problems scaling up into practical fusion triple products. Interest returned in the 1990s and as of 2019, FRCs were an active research area.

https://en.wikipedia.org/wiki/Field-reversed_configuration

Fusion power, processes and devices

Core topics

Nuclear fusion Timeline List of experiments Nuclear power Nuclear reactor Atomic nucleus Fusion energy gain factor Lawson criterion Magnetohydrodynamics Neutron Plasma

Processes,

methods

Confinement

type

Gravitational

Alpha process Triple-alpha process CNO cycle Fusor Helium flash Nova remnants Proton-proton chain Carbon-burning Lithium burning Neon-burning Oxygen-burning Silicon-burning R-process S-process

Magnetic

Dense plasma focus Field-reversed configuration Levitated dipole Magnetic mirror Bumpy torus Reversed field pinch Spheromak Stellarator Tokamak Spherical Z-pinch

Inertial

Bubble (acoustic) Laser-driven Ion-driven Magnetized Liner Inertial Fusion

Electrostatic

Fusor Polywell

Other forms

Colliding beam Magnetized target Migma Muon-catalyzed Pyroelectric

https://en.wikipedia.org/wiki/nuclear_cascade

https://en.wikipedia.org/wiki/Proton–proton_chain

https://en.wikipedia.org/wiki/CNO_cycle

https://en.wikipedia.org/wiki/Fusor_(astronomy)

https://en.wikipedia.org/wiki/Helium_flash

https://en.wikipedia.org/wiki/Fusion_energy_gain_factor

https://en.wikipedia.org/wiki/Aneutronic_fusion

Candidate reactions[edit]

Several nuclear reactions produce no neutrons on any of their branches. Those with the largest cross sections are these:

High nuclear cross section aneutronic reactions^[1]
Isotopes	Reaction
Deuterium - Helium-3	²D	+	³He	→		⁴He	+	¹p	+ 18.3 MeV
Deuterium - Lithium-6	²D	+	⁶Li	→	2	⁴He			+ 22.4 MeV
Proton - Lithium-6	¹p	+	⁶Li	→		⁴He	+	³He	+ 4.0 MeV
Helium-3 – Lithium-6	³He	+	⁶Li	→	2	⁴He	+	¹p	+ 16.9 MeV
Helium-3 - Helium-3	³He	+	³He	→		⁴He	+	2 ¹p	+ 12.86 MeV
Proton – Lithium-7	¹p	+	⁷Li	→	2	⁴He			+ 17.2 MeV
Proton – Boron-11	¹p	+	¹¹B	→	3	⁴He			+ 8.7 MeV
Proton – Nitrogen	¹p	+	¹⁵N	→		¹²C	+	⁴He	+ 5.0 MeV

Energy capture[edit]

Aneutronic fusion produces energy in the form of charged particles instead of neutrons. This means that energy from aneutronic fusion could be captured using direct conversion instead of the steam cycle. Direct conversion techniques can either be inductive, based on changes in magnetic fields, electrostatic, based on pitting charged particles against an electric field, or photoelectric, in which light energy is captured. In a pulsed mode.^[50]

Electrostatic direct conversion uses the motion of charged particles to create voltage. This voltage drives electricity in a wire. This becomes electrical power, the reverse of most phenomena that use a voltage to put a particle in motion. Direct energy conversion does the opposite, using particle motion to produce a voltage. It has been described as a linear accelerator running backwards.^[51] An early supporter of this method was Richard F. Post at Lawrence Livermore. He proposed to capture the kinetic energy of charged particles as they were exhausted from a fusion reactor and convert this into voltage to drive current.^[52] Post helped develop the theoretical underpinnings of direct conversion, later demonstrated by Barr and Moir. They demonstrated a 48 percent energy capture efficiency on the Tandem Mirror Experiment in 1981.^[53]

Aneutronic fusion loses much of its energy as light. This energy results from the acceleration and deceleration of charged particles. These speed changes can be caused by Bremsstrahlung radiation or cyclotron radiation or synchrotron radiation or electric field interactions. The radiation can be estimated using the Larmor formula and comes in the X-ray, IR, UV and visible spectra. Some of the energy radiated as X-rays may be converted directly to electricity. Because of the photoelectric effect, X-rays passing through an array of conducting foils transfer some of their energy to electrons, which can then be captured electrostatically. Since X-rays can go through far greater material thickness than electrons, many hundreds or thousands of layers are needed to absorb them.^[54]

History[edit]

The first practical MHD power research was funded in 1938 in the U.S. by Westinghouse in its Pittsburgh, Pennsylvania laboratories, headed by Hungarian Bela Karlovitz. The initial patent on MHD is by B. Karlovitz, U.S. Patent No. 2,210,918, "Process for the Conversion of Energy", August 13, 1940.

Former Yugoslavia development[edit]

Over more than a ten-year span, engineers in former Yugoslavian Institute of Thermal and Nuclear Technology (ITEN), Energoinvest Co., Sarajevo, had built the first experimental Magneto-Hydrodynamic facility power generator in 1989. It was here it was first patented.^[16]^[17]

U.S. development[edit]

In the 1980s, the U.S. Department of Energy began a vigorous multiyear program, culminating in a 1992 50 MW demonstration coal combustor at the Component Development and Integration Facility (CDIF) in Butte, Montana. This program also had significant work at the Coal-Fired-In-Flow-Facility (CFIFF) at University of Tennessee Space Institute.

This program combined four parts:

An integrated MHD topping cycle, with channel, electrodes and current control units developed by AVCO, later known as Textron Defence of Boston. This system was a Hall effect duct generator heated by pulverized coal, with a potassium ionisation seed. AVCO had developed the famous Mk. V generator, and had significant experience.
An integrated bottoming cycle, developed at the CDIF.
A facility to regenerate the ionization seed was developed by TRW. Potassium carbonate is separated from the sulphate in the fly ash from the scrubbers. The carbonate is removed, to regain the potassium.
A method to integrate MHD into preexisting coal plants. The Department of Energy commissioned two studies. Westinghouse Electric performed a study based on the Scholtz Plant of Gulf Power in Sneads, Florida. The MHD Development Corporation also produced a study based on the J.E. Corrette Plant of the Montana Power Company of Billings, Montana.

Initial prototypes at the CDIF were operated for short durations, with various coals: Montana Rosebud, and a high-sulphur corrosive coal, Illinois No. 6. A great deal of engineering, chemistry and material science was completed. After final components were developed, operational testing completed with 4,000 hours of continuous operation, 2,000 on Montana Rosebud, 2,000 on Illinois No. 6. The testing ended in 1993.^{[citation needed]}

Japanese development[edit]

The Japanese program in the late 1980s concentrated on closed-cycle MHD. The belief was that it would have higher efficiencies, and smaller equipment, especially in the clean, small, economical plant capacities near 100 megawatts (electrical) which are suited to Japanese conditions. Open-cycle coal-powered plants are generally thought to become economical above 200 megawatts.

The first major series of experiments was FUJI-1, a blow-down system powered from a shock tube at the Tokyo Institute of Technology. These experiments extracted up to 30.2% of enthalpy, and achieved power densities near 100 megawatts per cubic meter. This facility was funded by Tokyo Electric Power, other Japanese utilities, and the Department of Education. Some authorities believe this system was a disc generator with a helium and argon carrier gas and potassium ionization seed.

In 1994, there were detailed plans for FUJI-2, a 5 MWe continuous closed-cycle facility, powered by natural gas, to be built using the experience of FUJI-1. The basic MHD design was to be a system with inert gases using a disk generator. The aim was an enthalpy extraction of 30% and an MHD thermal efficiency of 60%. FUJI-2 was to be followed by a retrofit to a 300 MWe natural gas plant.

Australian development[edit]

In 1986, Professor Hugo Karl Messerle at The University of Sydney researched coal-fueled MHD. This resulted in a 28 MWe topping facility that was operated outside Sydney. Messerle also wrote one of the most recent reference works (see below), as part of a UNESCO education program.

A detailed obituary for Hugo is located on the Australian Academy of Technological Sciences and Engineering (ATSE) website.^[18]

Italian development[edit]

The Italian program began in 1989 with a budget of about 20 million $US, and had three main development areas:

MHD Modelling.
Superconducting magnet development. The goal in 1994 was a prototype 2 m long, storing 66 MJ, for an MHD demonstration 8 m long. The field was to be 5 teslas, with a taper of 0.15 T/m. The geometry was to resemble a saddle shape, with cylindrical and rectangular windings of niobium-titanium copper.
Retrofits to natural gas powerplants. One was to be at the Enichem-Anic factor in Ravenna. In this plant, the combustion gases from the MHD would pass to the boiler. The other was a 230 MW (thermal) installation for a power station in Brindisi, that would pass steam to the main power plant.

Chinese development[edit]

A joint U.S.-China national programme ended in 1992 by retrofitting the coal-fired No. 3 plant in Asbach.^{[citation needed]} A further eleven-year program was approved in March 1994. This established centres of research in:

The Institute of Electrical Engineering in the Chinese Academy of Sciences, Beijing, concerned with MHD generator design.
The Shanghai Power Research Institute, concerned with overall system and superconducting magnet research.
The Thermoenergy Research Engineering Institute at the Nanjing's Southeast University, concerned with later developments.

The 1994 study proposed a 10 W (electrical, 108 MW thermal) generator with the MHD and bottoming cycle plants connected by steam piping, so either could operate independently.

Russian developments[edit]

U-25 scale model

In 1971 the natural-gas fired U-25 plant was completed near Moscow, with a designed capacity of 25 megawatts. By 1974 it delivered 6 megawatts of power.^[19] By 1994, Russia had developed and operated the coal-operated facility U-25, at the High-Temperature Institute of the Russian Academy of Science in Moscow. U-25's bottoming plant was actually operated under contract with the Moscow utility, and fed power into Moscow's grid. There was substantial interest in Russia in developing a coal-powered disc generator. In 1986 the first industrial power plant with MHD generator was built, but in 1989 the project was cancelled before MHD launch and this power plant later joined to Ryazan Power Station as a 7th unit with ordinary construction.

https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator

Shocks and discontinuities are transition layers where the plasma properties change from one equilibrium state to another. The relation between the plasma properties on both sides of a shock or a discontinuity can be obtained from the conservative form of the magnetohydrodynamic (MHD) equations, assuming conservation of mass, momentum, energy and of $\nabla \cdot \mathbf {B}$ .

https://en.wikipedia.org/wiki/Shocks_and_discontinuities_(magnetohydrodynamics)

https://en.wikipedia.org/wiki/Helion_Energy

https://en.wikipedia.org/wiki/Magnetic_pressure

https://en.wikipedia.org/wiki/Tangential_and_normal_components

https://en.wikipedia.org/wiki/Density

https://en.wikipedia.org/wiki/thermodynamics

https://en.wikipedia.org/wiki/Speed_of_sound

https://en.wikipedia.org/wiki/Bow_shock

https://en.wikipedia.org/wiki/Category:Space_plasmas

https://en.wikipedia.org/wiki/Magnetic_confinement_fusion

https://en.wikipedia.org/wiki/Plasma_(physics)

https://en.wikipedia.org/wiki/Neutron

https://en.wikipedia.org/wiki/Levitated_dipole

https://en.wikipedia.org/wiki/Stellarator

https://en.wikipedia.org/wiki/Z-pinch

https://en.wikipedia.org/wiki/Thermonuclear_fusion#Confinement

https://en.wikipedia.org/wiki/Vacuum

https://en.wikipedia.org/wiki/Binding_energy#Nuclear_binding_energy_curve

https://en.wikipedia.org/wiki/R-process

https://en.wikipedia.org/wiki/Voitenko_compressor

https://en.wikipedia.org/wiki/Shear

https://en.wikipedia.org/wiki/conduction

https://en.wikipedia.org/wiki/compression

https://en.wikipedia.org/wiki/Spinor

https://en.wikipedia.org/wiki/Spin_(physics)

https://en.wikipedia.org/wiki/intrinsic_angular_momentum

https://en.wikipedia.org/wiki/scalar

https://en.wikipedia.org/wiki/eigen

https://en.wikipedia.org/wiki/zero

https://en.wikipedia.org/wiki/linear

https://en.wikipedia.org/wiki/Spin–statistics_theorem

https://en.wikipedia.org/wiki/Intrinsically_disordered_proteins

https://en.wikipedia.org/wiki/supramolecular_chemistry

https://en.wikipedia.org/wiki/Folding_(chemistry)

https://en.wikipedia.org/wiki/Category:Self-organization

https://en.wikipedia.org/wiki/Globular_protein

https://en.wikipedia.org/wiki/Scleroprotein

Spinors were introduced in geometry by Élie Cartan in 1913.^[1]^[d] In the 1920s physicists discovered that spinors are essential to describe the intrinsic angular momentum, or "spin", of the electron and other subatomic particles.^[e]

https://en.wikipedia.org/wiki/Spinor

https://en.wikipedia.org/wiki/Möbius_strip

https://en.wikipedia.org/wiki/Killing_spinor

https://en.wikipedia.org/wiki/Spinor_condensate

https://en.wikipedia.org/wiki/Killing_spinor

https://en.wikipedia.org/wiki/Spin–spin_relaxation

https://en.wikipedia.org/wiki/Spinor_spherical_harmonics

https://en.wikipedia.org/wiki/Orthogonal_group

https://en.wikipedia.org/wiki/Dirac_operator

https://en.wikipedia.org/wiki/Spin-1/2

https://en.wikipedia.org/wiki/Metal_spinning

https://en.wikipedia.org/wiki/Symplectic_spinor_bundle

https://en.wikipedia.org/wiki/Vorticity#Vortex_lines_and_vortex_tubes

https://en.wikipedia.org/wiki/Wingtip_vortices

https://en.wikipedia.org/wiki/Dust_devil

https://en.wikipedia.org/wiki/Negative_temperature#Two-dimensional_vortex_motion

https://en.wikipedia.org/wiki/Strake_(aeronautics)#Anti-spin_strakes

https://en.wikipedia.org/wiki/negative_matter

https://en.wikipedia.org/wiki/negative_resistance

https://en.wikipedia.org/wiki/negative_energy

https://en.wikipedia.org/wiki/Atomic_Age

https://en.wikipedia.org/wiki/Stimulated_emission#Small_signal_gain_equation

https://en.wikipedia.org/wiki/Ion

https://en.wikipedia.org/wiki/Second

https://en.wikipedia.org/wiki/Atomic_layer_deposition

https://en.wikipedia.org/wiki/Gas

https://en.wikipedia.org/wiki/Neon

https://en.wikipedia.org/wiki/Accretion_disk

https://en.wikipedia.org/wiki/astrophysical_jet

Roy Orbison - Oh, Pretty Woman

Above. Flo Rida (ft. Timbaland) - Elevator

Above. White Zombie - Thunder Kiss '65 (Official Video)

https://en.wikipedia.org/wiki/Ideal_gas_law

https://en.wikipedia.org/wiki/Degenerate_matter

https://en.wikipedia.org/wiki/Helium_flash

https://en.wikipedia.org/wiki/Gravitational_collapse

https://en.wikipedia.org/wiki/Triple-alpha_process

The triple-alpha process is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon.^[1]^[2]

Triple-alpha process in stars[edit]

Helium accumulates in the cores of stars as a result of the proton–proton chain reaction and the carbon–nitrogen–oxygen cycle.

https://en.wikipedia.org/wiki/Triple-alpha_process

https://en.wikipedia.org/wiki/Thermal_runaway

https://en.wikipedia.org/wiki/Accretion_(astrophysics)

https://en.wikipedia.org/wiki/Hydrostatic_equilibrium

https://en.wikipedia.org/wiki/Pressure-gradient_force

https://en.wikipedia.org/wiki/Thermal_conduction

https://en.wikipedia.org/wiki/Carbon_detonation

https://en.wikipedia.org/wiki/X-ray_burster

https://en.wikipedia.org/wiki/Category:Exotic_matter

https://en.wikipedia.org/wiki/Category:Nucleosynthesis

Once the muonic molecular ion state is formed, the shielding by the muon of the positive charges of the proton of the triton and the proton of the deuteron from each other allows the triton and the deuteron to tunnel through the Coulomb barrier in time span of order of a nanosecond^[13] The muon survives the d-t muon-catalyzed nuclear fusion reaction and remains available (usually) to catalyze further d-t muon-catalyzed nuclear fusions. Each exothermic d-t nuclear fusion releases about 17.6 MeV of energy in the form of a "very fast" neutron having a kinetic energy of about 14.1 MeV and an alpha particle α (a helium-4 nucleus) with a kinetic energy of about 3.5 MeV.^[6] An additional 4.8 MeV can be gleaned by having the fast neutrons moderated in a suitable "blanket" surrounding the reaction chamber, with the blanket containing lithium-6, whose nuclei, known by some as "lithions," readily and exothermically absorb thermal neutrons, the lithium-6 being transmuted thereby into an alpha particle and a triton.^{[note 6]}

https://en.wikipedia.org/wiki/Muon-catalyzed_fusion

https://en.wikipedia.org/wiki/Magnetohydrodynamics

https://en.wikipedia.org/wiki/Fusion_energy_gain_factor

In linguistics, and more precisely in traditional grammar, a cardinal numeral (or cardinal number word) is a part of speechused to count. Examples in English are the words one, two, three, and the compounds three hundred and forty-two and nine hundred and sixty. Cardinal numerals are classified as definite, and are related to ordinal numbers, such as the English first, second, and third, etc.^[1]^[2]^[3]

Description[edit]

The defining criterion of a shock wave is that the bulk velocity of the plasma drops from "supersonic" to "subsonic", where the speed of sound c_s is defined by $c_s^2 = \gamma p/ \rho$ where $\gamma$ is the ratio of specific heats, $p$ is the pressure, and $\rho$ is the density of the plasma.

A common complication in astrophysics is the presence of a magnetic field. For instance, the charged particles making up the solar wind follow spiral paths along magnetic field lines. The velocity of each particle as it gyrates around a field line can be treated similarly to a thermal velocity in an ordinary gas, and in an ordinary gas the mean thermal velocity is roughly the speed of sound. At the bow shock, the bulk forward velocity of the wind (which is the component of the velocity parallel to the field lines about which the particles gyrate) drops below the speed at which the particles are gyrating.

https://en.wikipedia.org/wiki/Bow_shock

Comet Grigg–Skjellerup (formally designated 26P/Grigg–Skjellerup) is a periodic comet. It was visited by the Giotto probe in July 1992.^[5]

https://en.wikipedia.org/wiki/26P/Grigg–Skjellerup

Brownleeite is a silicide mineral with chemical formula MnSi. It was discovered by researchers of the Johnson Space Center in Houston while analyzing the Pi Puppid particle shower of the comet 26P/Grigg-Skjellerup. The only other known natural manganese silicide is mavlyanovite, Mn₅Si₃.^[3]

Brownleeite
General
Category	Native element class, Fersilicite group
Formula (repeating unit)	MnSi
Strunz classification	1.XX.00
Dana classification	01.01.23.07
Crystal system	Isometric
Crystal class	Tetartoidal (23) H-M symbol: (23)
Space group	P2₁3
Identification
Crystal habit	Cubic grain in microscopic dust particle (< 2.5 μm)
References	^[1]^[2]

https://en.wikipedia.org/wiki/Brownleeite

Spontaneous emission is the process in which a quantum mechanical system (such as a molecule, an atom or a subatomic particle) transits from an excited energy state to a lower energy state (e.g., its ground state) and emits a quantized amount of energy in the form of a photon. Spontaneous emission is ultimately responsible for most of the light we see all around us; it is so ubiquitous that there are many names given to what is essentially the same process. If atoms (or molecules) are excited by some means other than heating, the spontaneous emission is called luminescence. For example, fireflies are luminescent. And there are different forms of luminescence depending on how excited atoms are produced (electroluminescence, chemiluminescence etc.). If the excitation is affected by the absorption of radiation the spontaneous emission is called fluorescence. Sometimes molecules have a metastable level and continue to fluoresce long after the exciting radiation is turned off; this is called phosphorescence. Figurines that glow in the dark are phosphorescent. Lasers start via spontaneous emission, then during continuous operation work by stimulated emission.

https://en.wikipedia.org/wiki/Spontaneous_emission

In quantum mechanics, a two-state system (also known as a two-level system) is a quantum system that can exist in any quantum superposition of two independent (physically distinguishable) quantum states. The Hilbert space describing such a system is two-dimensional. Therefore, a complete basis spanning the space will consist of two independent states. Any two-state system can also be seen as a qubit.

https://en.wikipedia.org/wiki/Two-state_quantum_system#Eigenvalues_of_the_Hamiltonian

https://en.wikipedia.org/wiki/Mineral

https://en.wikipedia.org/wiki/Columbite

https://en.wikipedia.org/wiki/Nsutite

https://en.wikipedia.org/wiki/Tantalite

https://en.wikipedia.org/wiki/Triploidite

https://en.wikipedia.org/wiki/Childrenite

https://en.wikipedia.org/wiki/Todorokite

https://en.wikipedia.org/wiki/Beryl#Bixbite

https://en.wikipedia.org/wiki/Calderite

https://en.wikipedia.org/wiki/Glaucochroite

https://en.wikipedia.org/wiki/Rhodonite

https://en.wikipedia.org/wiki/Tephroite

https://en.wikipedia.org/wiki/Arsenate

https://en.wikipedia.org/wiki/Axinite

https://en.wikipedia.org/wiki/Manganese_nodule

https://en.wikipedia.org/wiki/Wolframite

https://en.wikipedia.org/wiki/Two-state_quantum_system#Eigenvalues_of_the_Hamiltonian

A mirror galvanometer is an ammeter that indicates it has sensed an electric current by deflecting a light beam with a mirror. The beam of light projected on a scale acts as a long massless pointer. In 1826, Johann Christian Poggendorffdeveloped the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot galvanometerafter the spot of light produced in some models.

Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. The most common uses were as recording equipment for seismometers and submarine cables used for telegraphy.

In modern times, the term mirror galvanometer is also used for devices that move laser beams by rotating a mirror through a galvanometer set-up, often with a servo-like control loop. The name is often abbreviated as galvo.

Kelvin's galvanometer[edit]

The mirror galvanometer was improved significantly by William Thomson, later to become Lord Kelvin. He coined the term mirror galvanometer and patented the device in 1858. Thomson intended the instrument to read weak signal currents on very long submarine telegraph cables.^[1] This instrument was far more sensitive than any which preceded it, enabling the detection of the slightest defect in the core of a cable during its manufacture and submersion.

Thomson decided that he needed an extremely sensitive instrument after he took part in the failed attempt to lay a transatlantic telegraph cable in 1857. He worked on the device while waiting for a new expedition the following year. He first looked at improving a galvanometer used by Hermann von Helmholtz to measure the speed of nerve signals in 1849. Helmholtz's galvanometer had a mirror fixed to the moving needle, which was used to project a beam of light onto the opposite wall, thus greatly amplifying the signal. Thomson intended to make this more sensitive by reducing the mass of the moving parts, but in a flash of inspiration while watching the light reflected from his monocle suspended around his neck, he realised that he could dispense with the needle and its mounting altogether. He instead used a small piece of mirrored glass with a small piece of magnetised steel glued on the back. This was suspended by a thread in the magnetic field of the fixed sensing coil. In a hurry to try the idea, Thomson first used a hair from his dog, but later used a silk thread from the dress of his niece Agnes.^[1]

The following is adapted from a contemporary account of Thomson's instrument:^[2]

The mirror galvanometer consists of a long fine coil of silk-covered copper wire. In the heart of that coil, within a little air-chamber, a small round mirror is hung by a single fibre of floss silk, with four tiny magnets cemented to its back. A beam of light is thrown from a lamp upon the mirror, and reflected by it upon a white screen or scale a few feet distant, where it forms a bright spot of light. When there is no current on the instrument, the spot of light remains stationary at the zero position on the screen; but the instant a current traverses the long wire of the coil, the suspended magnets twist themselves horizontally out of their former position, the mirror is inclined with them, and the beam of light is deflected along the screen to one side or the other, according to the nature of the current. If a positive electric current gives a deflection to the right of zero, a negative current will give a deflection to the left of zero, and vice versa.
The air in the little chamber surrounding the mirror is compressed at will, so as to act like a cushion, and deaden the movements of the mirror. The needle is thus prevented from idly swinging about at each deflection, and the separate signals are rendered abrupt. At a receiving station the current coming in from the cable has simply to be passed through the coil before it is sent into the ground, and the wandering light spot on the screen faithfully represents all its variations to the clerk, who, looking on, interprets these, and cries out the message word by word. The small weight of the mirror and magnets which form the moving part of this instrument, and the range to which the minute motions of the mirror can be magnified on the screen by the reflected beam of light, which acts as a long impalpable hand or pointer, render the mirror galvanometer marvellously sensitive to the current, especially when compared with other forms of receiving instruments. Messages could be sent from the United Kingdom to the United States through one Atlantic cable and back again through another, and there received on the mirror galvanometer, the electric current used being that from a toy battery made out of a lady's silver thimble, a grain of zinc, and a drop of acidulated water.
The practical advantage of this extreme delicacy is that the signal waves of the current may follow each other so closely as almost entirely to coalesce, leaving only a very slight rise and fall of their crests, like ripples on the surface of a flowing stream, and yet the light spot will respond to each. The main flow of the current will of course shift the zero of the spot, but over and above this change of place the spot will follow the momentary fluctuations of the current which form the individual signals of the message. What with this shifting of the zero and the very slight rise and fall in the current produced by rapid signalling, the ordinary land line instruments are quite unserviceable for work upon long cables.

Moving coil galvanometer

Moving coil galvanometer was developed independently by Marcel Deprez and Jacques-Arsène d'Arsonval about 1880. Deprez's galvanometer was developed for high currents, while D'Arsonval designed his to measure weak currents. Unlike in the Kelvin's galvanometer, in this type of galvanometer the magnet is stationary and the coil is suspended in the magnet gap. The mirror attached to the coil frame rotates together with it. This form of instrument can be more sensitive and accurate and it replaced the Kelvin's galvanometer in most applications. The moving coil galvanometer is practically immune to ambient magnetic fields. Another important feature is self-damping generated by the electro-magnetic forces due to the currents induced in the coil by its movements the magnetic field. These are proportional to the angular velocity of the coil.

In modern times, high-speed mirror galvanometers are employed in laser light shows to move the laser beams and produce colorful geometric patterns in fog around the audience. Such high speed mirror galvanometers have proved to be indispensable in industry for laser marking systems for everything from laser etching hand tools, containers, and parts to batch-coding semiconductor wafers in semiconductor device fabrication. They typically control X and Y directions on Nd:YAG and CO₂ laser markers to control the position of the infrared power laser spot. Laser ablation, laser beam machining and wafer dicing are all industrial areas where high-speed mirror galvanometers can be found.

This moving coil galvanometer is mainly used to measure very feeble or low currents of order 10⁻⁹ A.

To linearise the magnetic field across the coil throughout the galvanometer's range of movement, the d'Arsonval design of a soft iron cylinder is placed inside the coil without touching it. This gives a consistent radial field, rather than a parallel linear field.

Mathematical contexts[edit]

Countless results in number theory invoke the fundamental theorem of arithmetic and the algebraic properties of even numbers, so the above choices have far-reaching consequences. For example, the fact that positive numbers have unique factorizations means that one can determine whether a number has an even or odd number of distinct prime factors. Since 1 is not prime, nor does it have prime factors, it is a product of 0 distinct primes; since 0 is an even number, 1 has an even number of distinct prime factors. This implies that the Möbius function takes the value μ(1) = 1, which is necessary for it to be a multiplicative function and for the Möbius inversion formula to work.^[14]

Not being odd[edit]

A number $n$ is odd if there is an integer $k$ such that $n = 2 k + 1$ . One way to prove that zero is not odd is by contradiction: if $0 = 2 k + 1$ then $k = -1/2$ , which is not an integer.^[15] Since zero is not odd, if an unknown number is proven to be odd, then it cannot be zero. This apparently trivial observation can provide a convenient and revealing proof explaining why an odd number is nonzero.

A classic result of graph theory states that a graph of odd order (having an odd number of vertices) always has at least one vertex of even degree. (The statement itself requires zero to be even: the empty graph has an even order, and an isolated vertex has an even degree.)^[16] In order to prove the statement, it is actually easier to prove a stronger result: any odd-order graph has an odd number of even degree vertices. The appearance of this odd number is explained by a still more general result, known as the handshaking lemma: any graph has an even number of vertices of odd degree.^[17]Finally, the even number of odd vertices is naturally explained by the degree sum formula.

Sperner's lemma is a more advanced application of the same strategy. The lemma states that a certain kind of coloring on a triangulation of a simplexhas a subsimplex that contains every color. Rather than directly construct such a subsimplex, it is more convenient to prove that there exists an odd number of such subsimplices through an induction argument.^[18] A stronger statement of the lemma then explains why this number is odd: it naturally breaks down as (n + 1) + n when one considers the two possible orientations of a simplex.^[19]

Even-odd alternation[edit]

Recursive definition of natural number parity

The fact that zero is even, together with the fact that even and odd numbers alternate, is enough to determine the parity of every other natural number. This idea can be formalized into a recursive definition of the set of even natural numbers:

0 is even.
(n + 1) is even if and only if n is not even.

This definition has the conceptual advantage of relying only on the minimal foundations of the natural numbers: the existence of 0 and of successors. As such, it is useful for computer logic systems such as LF and the Isabelle theorem prover.^[20] With this definition, the evenness of zero is not a theorem but an axiom. Indeed, "zero is an even number" may be interpreted as one of the Peano axioms, of which the even natural numbers are a model.^[21] A similar construction extends the definition of parity to transfinite ordinal numbers: every limit ordinal is even, including zero, and successors of even ordinals are odd.^[22]

Non-convex polygon penetrated by an arrow, labeled 0 on the outside, 1 on the inside, 2 on the outside, etc.

Point in polygon test

The classic point in polygon test from computational geometry applies the above ideas. To determine if a point lies within a polygon, one casts a ray from infinity to the point and counts the number of times the ray crosses the edge of polygon. The crossing number is even if and only if the point is outside the polygon. This algorithmworks because if the ray never crosses the polygon, then its crossing number is zero, which is even, and the point is outside. Every time the ray does cross the polygon, the crossing number alternates between even and odd, and the point at its tip alternates between outside and inside.^[23]

A graph with 9 vertices, alternating colors, labeled by distance from the vertex on the left

Constructing a bipartition

In graph theory, a bipartite graph is a graph whose vertices are split into two colors, such that neighboring vertices have different colors. If a connected graph has no odd cycles, then a bipartition can be constructed by choosing a base vertex v and coloring every vertex black or white, depending on whether its distance from v is even or odd. Since the distance between v and itself is 0, and 0 is even, the base vertex is colored differently from its neighbors, which lie at a distance of 1.^[24]

Algebraic patterns[edit]

Integers −4 through +4 arranged in a corkscrew, with a straight line running through the evens

2Z (blue) as subgroup of Z

In abstract algebra, the even integers form various algebraic structuresthat require the inclusion of zero. The fact that the additive identity (zero) is even, together with the evenness of sums and additive inverses of even numbers and the associativity of addition, means that the even integers form a group. Moreover, the group of even integers under addition is a subgroup of the group of all integers; this is an elementary example of the subgroup concept.^[16] The earlier observation that the rule "even − even = even" forces 0 to be even is part of a general pattern: any nonempty subset of an additive group that is closed under subtraction must be a subgroup, and in particular, must contain the identity.^[25]

Since the even integers form a subgroup of the integers, they partition the integers into cosets. These cosets may be described as the equivalence classes of the following equivalence relation: x ~ y if (x − y) is even. Here, the evenness of zero is directly manifested as the reflexivity of the binary relation ~.^[26] There are only two cosets of this subgroup—the even and odd numbers—so it has index 2.

Analogously, the alternating group is a subgroup of index 2 in the symmetric group on n letters. The elements of the alternating group, called even permutations, are the products of even numbers of transpositions. The identity map, an empty product of no transpositions, is an even permutation since zero is even; it is the identity element of the group.^[27]

The rule "even × integer = even" means that the even numbers form an ideal in the ring of integers, and the above equivalence relation can be described as equivalence modulo this ideal. In particular, even integers are exactly those integers k where k ≡ 0 (mod 2). This formulation is useful for investigating integer zeroes of polynomials.^[28]

2-adic order[edit]

There is a sense in which some multiples of 2 are "more even" than others. Multiples of 4 are called doubly even, since they can be divided by 2 twice. Not only is zero divisible by 4, zero has the unique property of being divisible by every power of 2, so it surpasses all other numbers in "evenness".^[1]

One consequence of this fact appears in the bit-reversed ordering of integer data types used by some computer algorithms, such as the Cooley–Tukey fast Fourier transform. This ordering has the property that the farther to the left the first 1 occurs in a number's binary expansion, or the more times it is divisible by 2, the sooner it appears. Zero's bit reversal is still zero; it can be divided by 2 any number of times, and its binary expansion does not contain any 1s, so it always comes first.^[29]

Although 0 is divisible by 2 more times than any other number, it is not straightforward to quantify exactly how many times that is. For any nonzero integer n, one may define the 2-adic order of n to be the number of times n is divisible by 2. This description does not work for 0; no matter how many times it is divided by 2, it can always be divided by 2 again. Rather, the usual convention is to set the 2-order of 0 to be infinity as a special case.^[30] This convention is not peculiar to the 2-order; it is one of the axioms of an additive valuation in higher algebra.^[31]

The powers of two—1, 2, 4, 8, ...—form a simple sequence of numbers of increasing 2-order. In the 2-adic numbers, such sequences actually convergeto zero.^[32]

https://en.wikipedia.org/wiki/Parity_of_zero

In mathematics, the classic Möbius inversion formula is a relation between pairs of arithmetic functions, each defined from the other by sums over divisors. It was introduced into number theory in 1832 by August Ferdinand Möbius.^[1]

A large generalization of this formula applies to summation over an arbitrary locally finite partially ordered set, with Möbius' classical formula applying to the set of the natural numbers ordered by divisibility: see incidence algebra.

https://en.wikipedia.org/wiki/Möbius_inversion_formula

In mathematics, the Möbius energy of a knot is a particular knot energy, i.e., a functional on the space of knots. It was discovered by Jun O'Hara, who demonstrated that the energy blows up as the knot's strands get close to one another.^[1] This is a useful property because it prevents self-intersection and ensures the result under gradient descent is of the same knot type.

https://en.wikipedia.org/wiki/Möbius_energy

Signed zero is zero with an associated sign. In ordinary arithmetic, the number 0 does not have a sign, so that −0, +0 and 0 are identical. However, in computing, some number representations allow for the existence of two zeros, often denoted by −0 (negative zero) and +0 (positive zero), regarded as equal by the numerical comparison operations but with possible different behaviors in particular operations. This occurs in the sign and magnitudeand ones' complement signed number representations for integers, and in most floating-point number representations. The number 0 is usually encoded as +0, but can be represented by either +0 or −0.

The IEEE 754 standard for floating-point arithmetic (presently used by most computers and programming languages that support floating-point numbers) requires both +0 and −0. Real arithmetic with signed zeros can be considered a variant of the extended real number line such that 1/−0 = −∞and 1/+0 = +∞; division is only undefined for ±0/±0 and ±∞/±∞.

Negatively signed zero echoes the mathematical analysis concept of approaching 0 from below as a one-sided limit, which may be denoted by x → 0⁻, x → 0−, or x → ↑0. The notation "−0" may be used informally to denote a negative number that has been rounded to zero. The concept of negative zero also has some theoretical applications in statistical mechanics and other disciplines.

It is claimed that the inclusion of signed zero in IEEE 754 makes it much easier to achieve numerical accuracy in some critical problems,^[1] in particular when computing with complex elementary functions.^[2] On the other hand, the concept of signed zero runs contrary to the general assumption made in most mathematical fields that negative zero is the same thing as zero. Representations that allow negative zero can be a source of errors in programs, if software developers do not take into account that while the two zero representations behave as equal under numeric comparisons, they yield different results in some operations.

https://en.wikipedia.org/wiki/Signed_zero

The zero-energy universe hypothesis proposes that the total amount of energy in the universe is exactly zero: its amount of positive energy in the form of matter is exactly canceled out by its negative energy in the form of gravity.^[1] Some physicists, such as Lawrence Krauss, Stephen Hawking or Alexander Vilenkin, call or called this state "a universe from nothingness", although the zero-energy universe model requires both a matter field with positive energy and a gravitational field with negative energy to exist.^[2] The hypothesis is broadly discussed in popular sources.^[3]^[4]^[5]

https://en.wikipedia.org/wiki/Zero-energy_universe

Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity. It is the potential energy associated with the gravitational field, which is released (converted into kinetic energy) when the objects fall towards each other. Gravitational potential energy increases when two objects are brought further apart.

For two pairwise interacting point particles, the gravitational potential energy $U$ is given by

U=-{\frac {GMm}{R}},

where $M$ and $m$ are the masses of the two particles, $R$ is the distance between them, and $G$ is the gravitational constant.^[1]

Close to the Earth's surface, the gravitational field is approximately constant, and the gravitational potential energy of an object reduces to

U=mgh

where $m$ is the object's mass, $g=GM_{\text{E}}/R_{\text{E}}^{2}$ is the gravity of Earth, and $h$ is the height of the object's center of mass above a chosen reference level.^[1]

https://en.wikipedia.org/wiki/Gravitational_energy

Energy

Outline History Index

Fundamental

concepts

Energy Units Conservation of energy Energetics Energy transformation Energy condition Energy transition Energy level Energy system Mass Negative mass Mass–energy equivalence Power Thermodynamics Quantum thermodynamics Laws of thermodynamics Thermodynamic system Thermodynamic state Thermodynamic potential Thermodynamic free energy Irreversible process Thermal reservoir Heat transfer Heat capacity Volume (thermodynamics) Thermodynamic equilibrium Thermal equilibrium Thermodynamic temperature Isolated system Entropy Free entropy Entropic force Negentropy Work Exergy Enthalpy

Types

Kinetic Internal Thermal Potential Gravitational Elastic Electric potential energy Mechanical Interatomic potential Quantum potential Electrical Magnetic Ionization Radiant Binding Nuclear binding energy Gravitational binding energy Quantum chromodynamics binding energy Dark Quintessence Phantom Negative Chemical Rest Sound energy Surface energy Vacuum energy Zero-point energy Quantum potential Quantum fluctuation

Energy carriers

Radiation Enthalpy Mechanical wave Sound wave Fuel fossil fuel Heat Latent heat Work Electricity Battery Capacitor

Primary energy

Fossil fuel Coal Petroleum Natural gas Nuclear fuel Natural uranium Radiant energy Solar Wind Hydropower Marine energy Geothermal Bioenergy Gravitational energy

Energy system

components

Energy engineering Oil refinery Electric power Fossil fuel power station Cogeneration Integrated gasification combined cycle Nuclear power Nuclear power plant Radioisotope thermoelectric generator Solar power Photovoltaic system Concentrated solar power Solar thermal energy Solar power tower Solar furnace Wind power Wind farm Airborne wind energy Hydropower Hydroelectricity Wave farm Tidal power Geothermal power Biomass

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Misc.

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Category Category Commons page Commons Portal Portal WikiProject WikiProject

Categories: Forms of energyGravityConservation lawsTensors in general relativity

https://en.wikipedia.org/wiki/Gravitational_energy

https://en.wikipedia.org/wiki/Outline_of_energy

https://en.wikipedia.org/wiki/Retroreflector

https://en.wikipedia.org/wiki/Index_of_energy_articles

Primary energy (PE) is an energy form found in nature that has not been subjected to any human engineeredconversion process. It is energy contained in raw fuels, and other forms of energy, including waste, received as input to a system. Primary energy can be non-renewable or renewable.

https://en.wikipedia.org/wiki/Primary_energy

Effect of Reflection from a Moving Mirror on the Velocity of Light

revolving mirrors were mounted on the shaft of an electric motor the speed of which (measured by a speed counter) could be varied from zero to 1800 revolutions

https://en.wikipedia.org/w/index.php?title=Special:Search&limit=20&offset=20&profile=default&search=zero+mirror&ns0=1&searchToken=aw620sr4m8vbym40b5piue9p6

https://en.wikipedia.org/wiki/Center_of_curvature

In politics, “poodle” is an insult used to describe a politician who obediently or passively follows the lead of others.^[1] It is considered to be equivalent to lackey.^[2] Usage of the term is thought to relate to the passive and obedient nature of the type of dog. Colette Avital unsuccessfully tried to have the term’s use banned from the Knesset in June 2001.^[3]

During the 2000s, it was used against Tony Blair with regard to his close relationship with George W. Bush and the involvement of the United Kingdom in the Iraq War. The singer George Michael infamously used it in his song “Shoot the Dog” in July 2002, the video of which showed Blair as the “poodle” on the lawn of the White House.^[4] However, it has somewhat of a longer history as a label to criticise British Prime Ministers who are perceived to be too close to the United States.^[5]


Other names	German: Pudel French: Caniche
Origin	Germany or France (see history)

Techniques[edit]

The main techniques associated with the use of a Schlenk line include:

counterflow additions, where air-stable reagents are added to the reaction vessel against a flow of inert gas;
the use of syringes and rubber septa to transfer liquids and solutions;^[3]
cannula transfer, where liquids or solutions of air-sensitive reagents are transferred between different vessels stoppered with septa using a long thin tube known as a cannula. Liquid flow is supported by vacuum or inert-gas pressure.^[4]

Glassware are usually connected by tightly fitting and greased ground glass joints. Round bends of glass tubing with ground glass joints may be used to adjust the orientation of various vessels. Glassware is necessarily purged of outside air by alternating application of vacuum and inert gas. The solvents and reagents that are used are also purged of air and water using various methods.

Filtration under inert conditions poses a special challenge that is usually tackled with specialized glassware. A Schlenk filter consists of sintered glass funnel fitted with joints and stopcocks. By fitting the pre-dried funnel and receiving flask to the reaction flask against a flow of nitrogen, carefully inverting the set-up, and turning on the vacuum appropriately, the filtration may be accomplished with minimal exposure to air.

Dangers[edit]

The main dangers associated with the use of a Schlenk line are the risks of an implosion or explosion. An implosion can occur due to the use of vacuum and flaws in the glass apparatus.

An explosion can occur due to the common use of liquid nitrogen in the cold trap, used to protect the vacuum pump from solvents. If a reasonable amount of air is allowed to enter the Schlenk line, liquid oxygen can condense into the cold trap as a pale blue liquid. An explosion may occur due to reaction of the liquid oxygen with any organic compounds also in the trap.

Gallery[edit]

Vacuum/gas manifold setup: 1 inert gas in, 2 inert gas out (to bubbler), 3 vacuum (to cold traps) 4 reaction line, 5 Teflon tap to gas, 6 Teflon tap to vacuum
Vacuum/gas manifold setup: 1 inert gas in, 2 inert gas out (to bubbler), 3 vacuum (to cold traps), 4 reaction line, 5 double oblique stopcock (i.e. a glass tap with 2 separate parallel "channels/lines" that run diagonal to the axis of the tap)
The two reactants for an aldol reaction are prepared in adjacent flasks, ready for one to be transferred to the other while maintaining air-free conditions
A yellow suspension is filtered through a sintered-glass funnel into another Schlenk flask under air-free conditions

External links[edit]

Rob Toreki (25 May 2004). "Schlenk Lines and Vacuum Lines". The Glassware Gallery. Interactive Learning Paradigms Incorporated.
Preparation of a Manganese oxide column for inert gas purification from oxygen traces

https://en.wikipedia.org/wiki/Schlenk_line

Constituents[edit]

The lower compartment of the desiccator contains lumps of silica gel, freshly calcined quicklime, Drierite or (not as effective) anhydrous calcium chlorideto absorb water vapor. The substance needing desiccation is put in the upper compartment, usually on a glazed, perforated ceramic plate. The ground-glass rim of the desiccator lid must be greased with a thin layer of vacuum grease, petroleum jelly or other lubricant to ensure an airtight seal.

In order to prevent damage to a desiccator the lid should be carefully slid on and off instead of being directly placed onto the base.^[1]

Operation[edit]

In laboratory use, the most common desiccators are circular and made of heavy glass. There is usually a removable platform on which the items to be stored are placed. The desiccant, usually an otherwise-inert solid such as silica gel, fills the space under the platform. Colour changing silica may be used to indicate when it should be refreshed. Indication gels typically change from blue to pink as they absorb moisture but other colours may be used.

A stopcock may be included to permit the desiccator to be evacuated. Such models are usually known as vacuum desiccators. When a vacuum is to be applied, it is a common practice to criss-cross the vacuum desiccator with tape, or to place it behind a screen to minimize damage or injury caused by an implosion. To maintain a good seal, vacuum grease is usually applied to the flanges.

Operation[edit]

The drying pistol consists of two concentric barrels; the inner is connected to a vacuum source via a trap.^[3] The outer barrel is connected at the bottom to a round bottom flask, and a condenser. To operate the drying pistol, a sample is placed within the inner barrel, and the barrel is evacuated. The round bottom flask, filled with an appropriate solvent, is heated to a boil. Hot vapors warm the inner barrel; losses are avoided with the condenser. By choosing the appropriate solvent, the temperature at which the sample is dried can be selected.

The trap is filled with an appropriate material: water is removed with phosphorus pentoxide, acidic gases by potassium or sodium hydroxide, and organic solvents by thin pieces of paraffin. However, use of these agents has been shown to have little efficacy. Generally, the main impurity to be removed is water.^[2]^[4]

This set-up allows the desiccation of heat-sensitive compounds under relatively mild conditions. Removing these trace impurities is especially important to give good results for elemental analysis and gravimetric analysis.

https://en.wikipedia.org/wiki/Abderhalden%27s_drying_pistol

Pages in category "Laboratory glassware"

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https://en.wikipedia.org/wiki/Category:Vacuum_systems

A vacuum furnace is a type of furnace in which the product in the furnace is surrounded by a vacuum during processing. The absence of air or other gases prevents oxidation, heat loss from the product through convection, and removes a source of contamination. This enables the furnace to heat materials (typically metals and ceramics) to temperatures as high as 3,000 °C (5,432 °F) ^[1] with select materials. Maximum furnace temperatures and vacuum levels depend on melting points and vapor pressures of heated materials. Vacuum furnaces are used to carry out processes such as annealing, brazing, sintering and heat treatment with high consistency and low contamination.

Characteristics of a vacuum furnace are:

Uniform temperatures in the range. 800–3,000 °C (1,500–5,400 °F)
Commercially available vacuum pumping systems can reach vacuum levels as low as 1×10⁻¹¹ torrs (1.3×10⁻¹¹ mbar; 1.3×10⁻¹⁴ atm)
Temperature can be controlled within a heated zone, typically surrounded by heat shielding or insulation.
Low contamination of the product by carbon, oxygen and other gases.
Vacuum pumping systems remove low temperature by-products from the process materials during heating, resulting in a higher purity end product.
Quick cooling (quenching) of product can be used to shorten process cycle times.
The process can be computer controlled to ensure repeatability.

Heating metals to high temperatures in open to atmosphere normally causes rapid oxidation, which is undesirable. A vacuum furnace removes the oxygen and prevents this from happening.

An inert gas, such as Argon, is often used to quickly cool the treated metals back to non-metallurgical levels (below 400 °F [200 °C]) after the desired process in the furnace.^[2] This inert gas can be pressurized to two times atmosphere or more, then circulated through the hot zone area to pick up heat before passing through a heat exchanger to remove heat. This process continues until the desired temperature is reached.

Vacuum furnaces are used in a wide range of applications in both production industries and research laboratories.

At temperatures below 1200 °C, a vacuum furnace is commonly used for the heat treatment of steel alloys. Many general heat treating applications involve the hardening and tempering of a steel part to make it strong and tough through service. Hardening involves heating the steel to a predetermined temperature, then cooling it rapidly in water, oil or suitable medium.

A further application for vacuum furnaces is Vacuum Carburizing also known as Low Pressure Carburizing or LPC. In this process, a gas (such as acetylene) is introduced as a partial pressure into the hot zone at temperatures typically between 1,600 and 1,950 °F (870 and 1,070 °C). The gas disassociates into its constituent elements (in this case carbon and hydrogen). The carbon is then diffused into the surface area of the part. This function is typically repeated, varying the duration of gas input and diffusion time. Once the workload is properly "cased", the metal is quenched using oil or high pressure gas (HPGQ). For HPGQ, nitrogen or, for faster quench helium, is commonly used. This process is also known as case hardening.

Another low temperature application of vacuum furnaces is debinding, a process for the removal of binders. Heat is applied under a vacuum in a sealed chamber, melting or vaporizing the binder from the aggregate. The binder is evacuated by the pumping system and collected or purged downstream. The material with a higher melting point is left behind in a purified state and can be further processed.

Vacuum furnaces capable of temperatures above 1200 °C are used in various industry sectors such as electronics, medical, crystal growth, energy and artificial gems. The processing of high temperature materials, both of metals and nonmetals, in a vacuum environment allows annealing, brazing, purification, sintering and other processes to take place in a controlled manner.

https://en.wikipedia.org/wiki/Vacuum_furnace

Goura, Phthiotis was a village located within Phthiotis, Greece.^[1] Sometime around the late 19th century, a beehive tomb burial structure constructed from stone was discovered in Goura.^[1] Local people converted the tomb into a lime kiln, and it contained rings, gold, silver, painted vases and bones.^[1]

https://en.wikipedia.org/wiki/Goura,_Phthiotis

A flue-gas stack, also known as a smoke stack, chimney stack or simply as a stack, is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. Flue gases are produced when coal, oil, natural gas, wood or any other fuel is combusted in an industrial furnace, a power plant's steam-generating boiler, or other large combustion device. Flue gas is usually composed of carbon dioxide (CO₂) and water vapor as well as nitrogen and excess oxygen remaining from the intake combustion air. It also contains a small percentage of pollutants such as particulate matter, carbon monoxide, nitrogen oxides and sulfur oxides. The flue gas stacks are often quite tall, up to 400 metres (1300 feet) or more, so as to disperse the exhaust pollutants over a greater area and thereby reduce the concentration of the pollutants to the levels required by governmental environmental policy and environmental regulation.

When the flue gases are exhausted from stoves, ovens, fireplaces, heating furnaces and boilers, or other small sources within residential abodes, restaurants, hotels, or other public buildings and small commercial enterprises, their flue gas stacks are referred to as chimneys.

The stack effect in chimneys: the gauges represent absolute air pressure and the airflow is indicated with light grey arrows. The gauge dials move clockwise with increasing pressure.

Flue-gas stack draft[edit]

The stack effect in chimneys: the gauges represent absolute air pressure and the airflow is indicated with light grey arrows. The gauge dials move clockwise with increasing pressure.

The combustion flue gases inside the flue gas stacks are much hotter than the ambient outside air and therefore less dense than the ambient air. That causes the bottom of the vertical column of hot flue gas to have a lower pressure than the pressure at the bottom of a corresponding column of outside air. That higher pressure outside the chimney is the driving force that moves the required combustion air into the combustion zone and also moves the flue gas up and out of the chimney. That movement or flow of combustion air and flue gas is called "natural draft", "natural ventilation", "chimney effect", or "stack effect". The taller the stack, the more draft is created.

The equation below provides an approximation of the pressure difference, ΔP, (between the bottom and the top of the flue gas stack) that is created by the draft:^[3]^[4]

\Delta P=Cah{\bigg (}{\frac {1}{T_{o}}}-{\frac {1}{T_{i}}}{\bigg )}

where:

ΔP: available pressure difference, in Pa
C = 0.0342
a: atmospheric pressure, in Pa
h: height of the flue gas stack, in m
T_o: absolute outside air temperature, in K
T_i: absolute average temperature of the flue gas inside the stack, in K.

The above equation is an approximation because it assumes that the molar mass of the flue gas and the outside air are equal and that the pressure drop through the flue gas stack is quite small. Both assumptions are fairly good but not exactly accurate.

https://en.wikipedia.org/wiki/Flue-gas_stack

Stack effect or chimney effect is the movement of air into and out of buildings, chimneys, flue-gas stacks, or other containers, resulting from air buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor air density resulting from temperature and moisture differences. The result is either a positive or negative buoyancy force. The greater the thermal difference and the height of the structure, the greater the buoyancy force, and thus the stack effect. The stack effect helps drive natural ventilation, air infiltration, and fires (e.g. the Kaprun tunnel fire, King's Cross underground station fireand the Grenfell Tower fire).

Stack effect in buildings[edit]

Since buildings are not totally sealed (at the very minimum, there is always a ground level entrance), the stack effect will cause air infiltration. During the heating season, the warmer indoor air rises up through the building and escapes at the top either through open windows, ventilation openings, or unintentional holes in ceilings, like ceiling fans and recessed lights. The rising warm air reduces the pressure in the base of the building, drawing cold air in through either open doors, windows, or other openings and leakage. During the cooling season, the stack effect is reversed, but is typically weaker due to lower temperature differences.^[1]

https://en.wikipedia.org/wiki/Stack_effect

The Pressure-Temperature-time path (P-T-t path) is a record of the pressure and temperature(P-T) conditions that a rock experienced in a metamorphic cycle from burial and heating to upliftand exhumation to the surface.^[1] Metamorphism is a dynamic process which involves the changes in minerals and textures of the pre-existing rocks (protoliths) under different P-T conditions in solid state.^[2] The changes in pressures and temperatures with time experienced by the metamorphic rocks are often investigated by petrological methods, radiometric dating techniques and thermodynamic modeling.^[1]^[2]

Metamorphic minerals are unstable upon changing P-T conditions.^[1]^[3] The original minerals are commonly destroyed during solid state metamorphism and react to grow into new minerals that are relatively stable.^[1]^[3] Water is generally involved in the reaction, either from the surroundings or generated by the reaction itself.^[3] Usually, a large amount of fluids (e.g. water vapor, gas etc.) escape under increasing P-T conditions e.g. burial.^[1] When the rock is later uplifted, due to the escape of fluids at an earlier stage, there is not enough fluids to permit all the new minerals to react back into the original minerals.^[1] Hence, the minerals are not fully in equilibrium when discovered on the surface.^[1] Therefore, the mineral assemblages in metamorphic rocks implicitly record the past P-T conditions that the rock has experienced, and investigating these minerals can supply information about the past metamorphic and tectonic history.^[1]

The P-T-t paths are generally classified into two types: clockwise P-T-t paths, which are related to collision origin, and involve high pressures followed by high temperatures;^[4] and anticlockwise P-T-t paths, which are usually of intrusion origin, and involve high temperatures before high pressures.^[4] (The "clockwise" and "anticlockwise" names refer to the apparent direction of the paths in the Cartesian space, where the x-axis is temperature, and the y-axis is pressure.^[3])

A schematic clockwise P-T-t path. Metamorphicminerals alter with the changing P-T condition with time without reaching complete phase equilibrium, making P-T-t path tracking possible. From 1910 Ma (i.e. 1910 million years ago) to 1840 Ma, the rock experienced an increase in P-T conditions and formed mineral garnet, which is attributed to burial and heating. After that, the rock was continuously heated to the peak temperature and formed mineral cordierite. Meanwhile, it went through a great decrease in pressure around 1840 Ma due to an uplift event. Finally, the continuous drop in pressure and temperature in 1800 Ma resulted from further erosion and exhumation. The peak pressure is found to be reached before the peak temperature, owing to the relatively poor thermal conductivity of the rock upon increasing P-T condition, while the rock instantaneously experienced the pressure changes. Garnet and cordierite do not reach complete equilibrium when discovered on the surface, leaving a print of the past P-T environments.

https://en.wikipedia.org/wiki/Pressure-temperature-time_path

Handbook of Meteorology/Distribution of Pressure

Atmospheric Pressure.—Practically all the movements of the air are due to differences in its temperature; but, inasmuch as differences in temperatureresult

The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure substances. The Antoine equation is derived from the Clausius–Clapeyron relation. The equation was presented in 1888 by the French engineer Louis Charles Antoine [fr] (1825–1897).^[1]

https://en.wikipedia.org/wiki/Antoine_equation

Internal pressure is a measure of how the internal energy of a system changes when it expands or contracts at constant temperature. It has the same dimensions as pressure, the SI unit of which is the pascal.

Internal pressure is usually given the symbol $\pi _{T}$ . It is defined as a partial derivative of internal energy with respect to volume at constant temperature:

$\pi _T = \left ( \frac{\partial U}{\partial V} \right )_T$

$https://en.wikipedia.org/wiki/Internal_pressure$

Pressure[edit]

The maximum air pressure (weight of the atmosphere) is at sea level and decreases at high altitude because the atmosphere is in hydrostatic equilibrium, wherein the air pressure is equal to the weight of the air above a given point on the planetary surface. The relation between decreased air pressure and high altitude can be equated to the density of a fluid, by way of the following hydrostatic equation:

{\frac {dP}{dz}}=-\rho g_{n}=-{\frac {mPg_{n}}{RT}}

where:

g_n is the standard gravity
ρ is the density

z is the altitude
P is the pressure
R is the gas constant
T is the thermodynamic (absolute) temperature
m is the molar mass^[3]

The atmosphere of the Earth is in five layers:
(i) the exosphere at 600+ km;
(ii) the thermosphere at 600 km;
(iii) the mesosphere at 95–120 km;
(iv) the stratosphere at 50–60 km; and
(v) the troposphere at 8–15 km.
The scale indicates that the layers’ distances from the planetary surface to the edge of the stratosphere is ±50 km, less than 1.0% of the radius of the Earth.

https://en.wikipedia.org/wiki/Troposphere#Pressure

The tropopause is the atmospheric boundary that demarcates the troposphere from the stratosphere; which are two of the five layers of the atmosphere of Earth. The tropopause is a thermodynamic gradient-stratification layer, that marks the end of the troposphere, and lies approximately 17 kilometres (11 mi) above the equatorial regions, and approximately 9 kilometres (5.6 mi) above the polar regions.

The atmosphere of planet Earth:The tropopause is between the troposphere and the stratosphere.

https://en.wikipedia.org/wiki/Tropopause

In fluid mechanics, potential vorticity (PV) is a quantity which is proportional to the dot product of vorticity and stratification. This quantity, following a parcel of air or water, can only be changed by diabatic or frictional processes. It is a useful concept for understanding the generation of vorticity in cyclogenesis (the birth and development of a cyclone), especially along the polar front, and in analyzing flow in the ocean.

Potential vorticity (PV) is seen as one of the important theoretical successes of modern meteorology. It is a simplified approach for understanding fluid motions in a rotating system such as the Earth's atmosphere and ocean. Its development traces back to the circulation theorem by Bjerknes in 1898,^[1]which is a specialized form of Kelvin's circulation theorem. Starting from Hoskins et al., 1985,^[2] PV has been more commonly used in operational weather diagnosis such as tracing dynamics of air parcels and inverting for the full flow field. Even after detailed numerical weather forecasts on finer scales were made possible by increases in computational power, the PV view is still used in academia and routine weather forecasts, shedding light on the synoptic scale features for forecasters and researchers.^[3]

Baroclinic instability requires the presence of a potential vorticity gradient along which waves amplify during cyclogenesis.

https://en.wikipedia.org/wiki/Potential_vorticity

In the context of meteorology, a solenoid is a tube-shaped region in the atmosphere where isobaric (constant pressure) and isopycnal (constant density) surfaces intersect, causing vertical circulation.^[1]^[2] They are so-named because they are driven by the solenoid term of the vorticity equation.^[3]Examples of solenoids include the sea breeze circulation and the mountain–plains solenoid.^[4]^[5]

https://en.wikipedia.org/wiki/Solenoid_(meteorology)

https://en.wikipedia.org/wiki/Category:Atmospheric_dynamics

A flow tracer is any fluid property used to track flow, magnitude, direction, and circulation patterns. Tracers can be chemical properties, such as radioactive material, or chemical compounds, physical properties, such as density, temperature, salinity, or dyes, and can be natural or artificially induced. Flow tracers are used in many fields, such as physics, hydrology, limnology, oceanography, environmental studies and atmospheric studies.

Conservative tracers remain constant following fluid parcels, whereas reactive tracers (such as compounds undergoing a mutual chemical reaction) grow or decay with time. Active tracersdynamically alter the flow of the fluid by changing fluid properties which appear in the equation of motion such as density or viscosity, while passive tracers have no influence on flow.^[1]

https://en.wikipedia.org/wiki/Flow_tracer

Perfluorocarbon tracers (PFTs) are a range of perfluorocarbons used in tracer applications. They are used by releasing the PFT at a certain point, and determining the concentration of that PFT at another set of points, allowing the flow from the source to the points to be determined.

https://en.wikipedia.org/wiki/Perfluorocarbon_tracer

Laser-driven muon sources seem to be the economical tipping point for making muon-catalyzed fusion reactors viable.^{[citation needed]}

^Process

[edit]

To create this effect, a stream of negative muons, most often created by decaying pions, is sent to a block that may be made up of all three hydrogen isotopes (protium, deuterium, and/or tritium), where the block is usually frozen, and the block may be at temperatures of about 3 kelvin (−270 degrees Celsius) or so. The muon may bump the electron from one of the hydrogen isotopes. The muon, 207 times more massive than the electron, effectively shields and reduces the electromagnetic repulsion between two nuclei and draws them much closer into a covalent bond than an electron can. Because the nuclei are so close, the strong nuclear force is able to kick in and bind both nuclei together. They fuse, release the catalytic muon (most of the time), and part of the original mass of both nuclei is released as energetic particles, as with any other type of nuclear fusion.

Deuterium-tritium (d-t or dt)[edit]

In the muon-catalyzed fusion of most interest, a positively charged deuteron (d), a positively charged triton (t), and a muon essentially form a positively charged muonic molecular heavy hydrogen ion (d-μ-t)⁺. The muon, with a rest mass 207 times greater than the rest mass of an electron,^[7] is able to drag the more massive triton and deuteron 207 times closer together to each other^[1] ^[2] in the muonic (d-μ-t)⁺ molecular ion than can an electron in the corresponding electronic (d-e-t)⁺ molecular ion. The average separation between the triton and the deuteron in the electronic molecular ion is about one angstrom (100 pm),^[6]^{[note 4]} so the average separation between the triton and the deuteron in the muonic molecular ion is 207 times smaller than that.^{[note 5]} Due to the strong nuclear force, whenever the triton and the deuteron in the muonic molecular ion happen to get even closer to each other during their periodic vibrational motions, the probability is very greatly enhanced that the positively charged triton and the positively charged deuteron would undergo quantum tunnelling through the repulsive Coulomb barrier that acts to keep them apart. Indeed, the quantum mechanical tunnelling probability depends roughly exponentially on the average separation between the triton and the deuteron, allowing a single muon to catalyze the d-t nuclear fusion in less than about half a picosecond, once the muonic molecular ion is formed.^[6]

^{https://en.wikipedia.org/wiki/Muon-catalyzed_fusion}

Colliding beam Magnetized target Migma Muon-catalyzed Pyroelectric

https://en.wikipedia.org/wiki/Magnetohydrodynamics

https://en.wikipedia.org/wiki/Fusion_energy_gain_factor

confinement magnetosphere

magneto

radioactive elements such as plutonium is complicated by the fact that solutions of this element can undergo disproportionation^[11] and as a result many different oxidation states can coexist at once.

https://en.wikipedia.org/wiki/Radiochemistry

09-27-2021-1746 - recognised a small spike at an energy of 803 kilo-electron volts (keV) as the gamma ray signal from polonium-210

Scientists at AWE were involved in testing for radioactive poison after the poisoning of Alexander Litvinenko. No gamma rays were detected; however, the BBC reported that a scientist at AWE, who had worked on Britain's early atomic bomb programme decades before, recognised a small spike at an energy of 803 kilo-electron volts (keV) as the gamma ray signal from polonium-210, a critical component of early nuclear bombs, which led to the correct diagnosis. Further tests using spectroscopy designed to detect alpha radiation confirmed the result.^[11]

https://en.wikipedia.org/wiki/Atomic_Weapons_Establishment

https://en.wikipedia.org/wiki/Modulated_neutron_initiator

design principles

https://en.wikipedia.org/wiki/Scaling_(geometry)

https://en.wikipedia.org/wiki/Reflection_(mathematics)

https://en.wikipedia.org/wiki/Norm_(mathematics)#Zero_norm

https://en.wikipedia.org/wiki/Uncorrelatedness_(probability_theory)

https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#Quaternion-derived_rotation_matrix

https://en.wikipedia.org/wiki/Reflection_symmetry

https://en.wikipedia.org/wiki/Graphite-moderated_reactor

In Euclidean geometry, uniform scaling (or isotropic scaling[1]) is a linear transformation that enlarges (increases) or shrinks (diminishes) objects by a scale factor that is the same in all directions. The result of uniform scaling is similar (in the geometric sense) to the original. A scale factor of 1 is normally allowed, so that congruent shapes are also classed as similar. Uniform scaling happens, for example, when enlarging or reducing a photograph, or when creating a scale model of a building, car, airplane, etc.
More general is scaling with a separate scale factor for each axis direction. Non-uniform scaling (anisotropic scaling) is obtained when at least one of the scaling factors is different from the others; a special case is directional scaling or stretching (in one direction). Non-uniform scaling changes the shape of the object; e.g. a square may change into a rectangle, or into a parallelogram if the sides of the square are not parallel to the scaling axes (the angles between lines parallel to the axes are preserved, but not all angles). It occurs, for example, when a faraway billboard is viewed from an oblique angle, or when the shadow of a flat object falls on a surface that is not parallel to it.
When the scale factor is larger than 1, (uniform or non-uniform) scaling is sometimes also called dilation or enlargement. When the scale factor is a positive number smaller than 1, scaling is sometimes also called contraction.
In the most general sense, a scaling includes the case in which the directions of scaling are not perpendicular. It also includes the case in which one or more scale factors are equal to zero (projection), and the case of one or more negative scale factors (a directional scaling by -1 is equivalent to a reflection).
Scaling is a linear transformation, and a special case of homothetic transformation. In most cases, the homothetic transformations are non-linear transformations.
Each iteration of the Sierpinski triangle contains triangles related to the next iteration by a scale factor of 1/2
https://en.wikipedia.org/wiki/Scaling_(geometry)
Zero norm[edit]In probability and functional analysis, the zero norm induces a complete metric topology for the space of measurable functions and for the F-spaceof sequences with F–norm [11] Here we mean by F-norm some real-valued function  on an F-space with distance d, such that  The F-norm described above is not a norm in the usual sense because it lacks the required homogeneity property.
Hamming distance of a vector from zero[edit]See also: Hamming distance and discrete metric
In metric geometry, the discrete metric takes the value one for distinct points and zero otherwise. When applied coordinate-wise to the elements of a vector space, the discrete distance defines the Hamming distance, which is important in coding and information theory. In the field of real or complex numbers, the distance of the discrete metric from zero is not homogeneous in the non-zero point; indeed, the distance from zero remains one as its non-zero argument approaches zero. However, the discrete distance of a number from zero does satisfy the other properties of a norm, namely the triangle inequality and positive definiteness. When applied component-wise to vectors, the discrete distance from zero behaves like a non-homogeneous "norm", which counts the number of non-zero components in its vector argument; again, this non-homogeneous "norm" is discontinuous.
In signal processing and statistics, David Donoho referred to the zero "norm" with quotation marks. Following Donoho's notation, the zero "norm" of x is simply the number of non-zero coordinates of x, or the Hamming distance of the vector from zero. When this "norm" is localized to a bounded set, it is the limit of p-norms as p approaches 0. Of course, the zero "norm" is not truly a norm, because it is not positive homogeneous. Indeed, it is not even an F-norm in the sense described above, since it is discontinuous, jointly and severally, with respect to the scalar argument in scalar–vector multiplication and with respect to its vector argument. Abusing terminology, some engineers[who?] omit Donoho's quotation marks and inappropriately call the number-of-nonzeros function the L0 norm, echoing the notation for the Lebesgue space of measurable functions.
https://en.wikipedia.org/wiki/Norm_(mathematics)#Zero_norm

In mathematics, a reflection (also spelled reflexion)[1] is a mapping from a Euclidean space to itself that is an isometry with a hyperplane as a set of fixed points; this set is called the axis (in dimension 2) or plane (in dimension 3) of reflection. The image of a figure by a reflection is its mirror image in the axis or plane of reflection. For example the mirror image of the small Latin letter p for a reflection with respect to a vertical axis would look like q. Its image by reflection in a horizontal axis would look like b. A reflection is an involution: when applied twice in succession, every point returns to its original location, and every geometrical object is restored to its original state.
The term reflection is sometimes used for a larger class of mappings from a Euclidean space to itself, namely the non-identity isometries that are involutions. Such isometries have a set of fixed points (the "mirror") that is an affine subspace, but is possibly smaller than a hyperplane. For instance a reflection through a point is an involutive isometry with just one fixed point; the image of the letter p under it would look like a d. This operation is also known as a central inversion (Coxeter 1969, §7.2), and exhibits Euclidean space as a symmetric space. In a Euclidean vector space, the reflection in the point situated at the origin is the same as vector negation. Other examples include reflections in a line in three-dimensional space. Typically, however, unqualified use of the term "reflection" means reflection in a hyperplane.
A figure that does not change upon undergoing a reflection is said to have reflectional symmetry.
Some mathematicians use "flip" as a synonym for "reflection".[2][3][4]
https://en.wikipedia.org/wiki/Reflection_(mathematics)

 A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds. All existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets. Sequential firing of a row of electromagnets accelerates the payload along a path. After leaving the path, the payload continues to move due to momentum.
https://en.wikipedia.org/wiki/Mass_driver

Monday, September 27, 202109-26-2021-2250 - Ferromagnetic resonance
 Ferromagnetic resonance, or FMR, is coupling between an electromagnetic wave and the magnetization of a medium through which it passes. This coupling induces a significant loss of power of the wave. The power is absorbed by the precessing magnetization (Larmor precession) of the material and lost as heat. For this coupling to occur, the frequency of the incident wave must be equal to the precession frequency of the magnetization (Larmor frequency) and the polarization of the wave must match the orientation of the magnetization.
This effect can be used for various applications such as spectroscopic techniques or conception of microwave devices.
The FMR spectroscopic technique is used to probe the magnetization of ferromagnetic materials. It is a standard tool for probing spin waves and spin dynamics. FMR is very broadly similar to electron paramagnetic resonance (EPR), and also somewhat similar to nuclear magnetic resonance (NMR), except that FMR probes the sample magnetization resulting from the magnetic moments of dipolar-coupled but unpaired electrons, while NMR probes the magnetic moment of atomic nuclei that are screened by the atomic or molecular orbitals surrounding such nuclei of non-zero nuclear spin.
The FMR resonance is also the basis of various high-frequency electronic devices, such as resonance isolators or circulators.
https://en.wikipedia.org/wiki/Ferromagnetic_resonance
Monday, September 27, 202109-26-2021-2303 - Helical railguns
 Helical railguns[1] are multi-turn railguns that reduce rail and brush current by a factor equal to the number of turns. Two rails are surrounded by a helical barrel and the projectile or re-usable carrier is cylindrical. The projectile is energized continuously by two brushes sliding along the rails, and two or more additional brushes on the projectile serve to energize and commute several windings of the helical barrel direction in front of and/or behind the projectile. The helical railgun is a cross between a railgun and a coilgun. They do not currently exist in a practical, usable form.
A helical railgun was built at MIT in 1980 and was powered by several banks of, for the time, large capacitors (approximately 4 farads). It was about 3 meters long, consisting of 2 meters of accelerating coil and 1 meter of decelerating coil. It was able to launch a glider or projectile about 500 meters.
See also[edit]Railgun
Plasma railgun
Coilgun
Mass driver
Ram accelerator
Light-gas gun
Electrothermal-chemical technology
Henry Kolm
References[edit]Kolm, H.; et al. (1980). "Electromagnetic Guns, Launchers, and Reaction Engines". 2Nd International Pulsed Power Conference. Massachusetts Institute of Technology: 42. Bibcode:1979pupo.conf...42K.
Specific^ http://ece-research.unm.edu/summa/notes/ELN/ELN%201.pdf

https://en.wikipedia.org/wiki/Helical_railgun
Monday, September 27, 202109-26-2021-2252 - Particle Radiation Range, Energy Density Tables, GravimetryMonday, September 27, 202109-26-2021-2113 - Corona Discharge electrical breakdown conductive leak charge into air, corona ring, ion wind, Hall effect thruster, Magnetohydrodynamic drive, Field-emission electric propulsion, plasma, Air ioniser, ion thruster, plasma actuator, AC, etc..

Elastomer items such as O-rings can suffer ozone cracking
ionization
thermoionic emission
electron melt

https://en.wikipedia.org/wiki/Corona_discharge

https://en.wikipedia.org/wiki/Ion_wind

https://en.wikipedia.org/wiki/Inelastic_collision

https://en.wikipedia.org/wiki/Elastomer

https://en.wikipedia.org/wiki/Atmospheric-pressure_chemical_ionization

https://en.wikipedia.org/wiki/Pressure_measurement#Ionization_gauge

https://en.wikipedia.org/wiki/Ionization_cooling

https://en.wikipedia.org/wiki/Non-ionizing_radiation

https://en.wikipedia.org/wiki/Photoelectric_effect

https://en.wikipedia.org/wiki/Fast_Low-Ionization_Emission_Region

https://en.wikipedia.org/wiki/Doubly_ionized_oxygen

https://en.wikipedia.org/wiki/Field_emission_gun

https://en.wikipedia.org/wiki/Particle_radiation

https://en.wikipedia.org/wiki/B-type_main-sequence_star

https://en.wikipedia.org/wiki/Paschen%27s_law#Impact_ionization

https://en.wikipedia.org/wiki/Thermal_ionization

https://en.wikipedia.org/wiki/Thermionic_emission

https://en.wikipedia.org/wiki/Radioactive_decay

https://en.wikipedia.org/wiki/Ionosphere#Layers_of_ionization

https://en.wikipedia.org/wiki/Particle-induced_X-ray_emission

https://en.wikipedia.org/wiki/Counts_per_minute

https://en.wikipedia.org/wiki/Ion-propelled_aircraft

https://en.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor

https://en.wikipedia.org/wiki/Nuclear_reactor

https://en.wikipedia.org/wiki/Gas_turbine_modular_helium_reactor

https://en.wikipedia.org/wiki/Gas-cooled_fast_reactor

https://en.wikipedia.org/wiki/Chemical_reactor

https://en.wikipedia.org/wiki/Pebble-bed_reactor

https://en.wikipedia.org/wiki/Liquid_fluoride_thorium_reactor

https://en.wikipedia.org/wiki/Molten_salt_reactor

https://en.wikipedia.org/wiki/RBMK

https://en.wikipedia.org/wiki/Fluidized_bed_reactor

https://en.wikipedia.org/wiki/Magnox

https://en.wikipedia.org/wiki/Gas_core_reactor_rocket

https://en.wikipedia.org/wiki/Breeder_reactor

Heat transfer to the working fluid (propellant) is by thermal radiation, mostly in the ultraviolet, given off by the fission gas at a working temperature of around 25,000 °C.

https://en.wikipedia.org/wiki/Gas_core_reactor_rocket

A gas nuclear reactor (or gas fueled reactor or vapor core reactor) is a proposed kind of nuclear reactor in which the nuclear fuel would be in a gaseous state rather than liquid or solid. In this type of reactor, the only temperature-limiting materials would be the reactor walls. Conventional reactors have stricter limitations because the core would melt if the fuel temperature were to rise too high. It may also be possible to confine gaseous fission fuel magnetically, electrostatically or electrodynamically so that it would not touch (and melt) the reactor walls. A potential benefit of the gaseous reactor core concept is that instead of relying on the traditional Rankine or Brayton conversion cycles, it may be possible to extract electricity magnetohydrodynamically, or with simple direct electrostatic conversion of the charged particles.

Theory of operation[edit]

The vapor core reactor (VCR), also called a gas core reactor (GCR), has been studied for some time. It would have a gas or vapor core composed of uranium tetrafluoride (UF₄) with some helium (⁴He) added to increase the electrical conductivity, the vapor core may also have tiny UF₄ droplets in it. It has both terrestrial and space based applications. Since the space concept doesn't necessarily have to be economical in the traditional sense, it allows the enrichment to exceed what would be acceptable for a terrestrial system. It also allows for a higher ratio of UF₄ to helium, which in the terrestrial version would be kept just high enough to ensure criticality in order to increase the efficiency of direct conversion. The terrestrial version is designed for a vapor core inlet temperature of about 1,500 K and exit temperature of 2,500 K and a UF₄ to helium ratio of around 20% to 60%. It is thought that the outlet temperature could be raised to that of the 8,000 K to 15,000 K range where the exhaust would be a fission-generated non-equilibrium electron gas, which would be of much more importance for a rocket design.

Energy production[edit]

For energy production purposes, one might use a container located inside a solenoid. The container is filled with gaseous uranium hexafluoride, where the uranium is enriched, to a level just short of criticality. Afterward, the uranium hexafluoride is compressed by external means, thus initiating a nuclear chain reaction and a great amount of heat, which in turn causes an expansion of the uranium hexafluoride. Since the UF₆ is contained within the vessel, it can't escape and thus compresses elsewhere. The result is a plasma wave moving in the container, and the solenoid converts some of its energy into electricity at an efficiency level of about 20%. In addition, the container must be cooled, and one can extract energy from the coolant by passing it through a heat exchanger and turbine system as in an ordinary thermal power plant.

However, there are enormous problems with corrosion during this arrangement, as the uranium hexafluoride is chemically very reactive.

https://en.wikipedia.org/wiki/Gaseous_fission_reactor

https://en.wikipedia.org/wiki/Water–gas_shift_reaction

https://en.wikipedia.org/wiki/Boiling_water_reactor

https://en.wikipedia.org/wiki/Pressurized_water_reactor

https://en.wikipedia.org/wiki/Heterogeneous_catalytic_reactor

https://en.wikipedia.org/wiki/Void_coefficient?wprov=srpw1_42

https://en.wikipedia.org/wiki/Nuclear_power#Advanced_fission_reactor_designs

https://en.wikipedia.org/wiki/Continuous_stirred-tank_reactor

Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD),^[1] is a chemical vapour deposition method used to produce single- or polycrystalline thin films. It is a process for growing crystalline layers to create complex semiconductor multilayer structures.^[2] In contrast to molecular-beam epitaxy (MBE), the growth of crystals is by chemical reaction and not physical deposition. This takes place not in vacuum, but from the gas phase at moderate pressures (10 to 760 Torr). As such, this technique is preferred for the formation of devices incorporating thermodynamically metastable alloys,^{[citation needed]} and it has become a major process in the manufacture of optoelectronics, such as Light-emitting diodes. It was invented in 1968 at North American Aviation (later Rockwell International) Science Center by Harold M. Manasevit.

Illustration of the process

https://en.wikipedia.org/wiki/Metalorganic_vapour-phase_epitaxy
https://en.wikipedia.org/wiki/Metalorganic_vapour-phase_epitaxy#Reactor_components

https://en.wikipedia.org/wiki/Pebble_bed_modular_reactor

https://en.wikipedia.org/wiki/Closed-cycle_gas_turbine

https://en.wikipedia.org/wiki/Liquid_metal_cooled_reactor

https://en.wikipedia.org/wiki/Pressurized_heavy-water_reactor

https://en.wikipedia.org/wiki/Steam-Generating_Heavy_Water_Reactor

https://en.wikipedia.org/wiki/Internal_circulation_reactor

https://en.wikipedia.org/wiki/X-energy

https://en.wikipedia.org/wiki/Fluid_catalytic_cracking

https://en.wikipedia.org/wiki/Fluid_catalytic_cracking#Reactor_and_regenerator

https://en.wikipedia.org/wiki/Laminar_flow_reactor

https://en.wikipedia.org/wiki/Subcritical_reactor

https://en.wikipedia.org/wiki/Stable_salt_reactor

https://en.wikipedia.org/wiki/Aqueous_homogeneous_reactor

https://en.wikipedia.org/wiki/Advanced_boiling_water_reactor

https://en.wikipedia.org/wiki/Integral_fast_reactor

https://en.wikipedia.org/wiki/Pressure_reactor

https://en.wikipedia.org/wiki/Fusion_power

https://en.wikipedia.org/wiki/Enriched_uranium#Gas_centrifuge

https://en.wikipedia.org/wiki/Mass_balance#Ideal_tank_reactor%2Fcontinuously_stirred_tank_reactor

https://en.wikipedia.org/wiki/Bioreactor

Monday, August 9, 2021

08-08-2021-2244 - Plasma PhysicsMonday, September 27, 202109-27-2021-1730 - Atomic Weapons Program, Chlorine-Iron Fire, List of Unusual Deaths, Radiochemistry, Natural Gas, Yield of a nuclear weapon, chalcogen, Windscale fire, modulated neutron initiator, metalloid, post-transition element, metals close to the border between metals and non metals, etc..
Monday, September 20, 202109-20-2021-1055 - eightfold way is an organizational scheme for a class of subatomic particles known as hadrons that led to the development of the quark model. 1961 Baryon decuplet

https://en.wikipedia.org/wiki/Rydberg_atom
https://en.wikipedia.org/wiki/Azimuthal_quantum_number
https://en.wikipedia.org/wiki/Binding_energy
https://en.wikipedia.org/wiki/Separation_energy

https://en.wikipedia.org/wiki/Photoionization
https://en.wikipedia.org/wiki/Photodissociation
https://en.wikipedia.org/wiki/Photoelectric_effect
https://en.wikipedia.org/wiki/Photovoltaics
https://en.wikipedia.org/wiki/Bond-dissociation_energy
https://en.wikipedia.org/wiki/Nuclear_physics

https://en.wikipedia.org/wiki/Powder_coating
https://en.wikipedia.org/wiki/Melt_electrospinning
https://en.wikipedia.org/wiki/Electrospinning
https://en.wikipedia.org/wiki/Electret
https://en.wikipedia.org/wiki/Overvoltage
https://en.wikipedia.org/wiki/Gaseous_fission_reactor
https://en.wikipedia.org/wiki/Electron-beam_technology

A gas nuclear reactor (or gas fueled reactor or vapor core reactor) is a proposed kind of nuclear reactor in which the nuclear fuel would be in a gaseous state rather than liquid or solid. In this type of reactor, the only temperature-limiting materials would be the reactor walls. Conventional reactors have stricter limitations because the core would melt if the fuel temperature were to rise too high. It may also be possible to confine gaseous fission fuel magnetically, electrostatically or electrodynamically so that it would not touch (and melt) the reactor walls. A potential benefit of the gaseous reactor core concept is that instead of relying on the traditional Rankine or Brayton conversion cycles, it may be possible to extract electricity magnetohydrodynamically, or with simple direct electrostatic conversion of the charged particles.
https://en.wikipedia.org/wiki/Gaseous_fission_reactor

https://en.wikipedia.org/wiki/Electrospinning

https://en.wikipedia.org/wiki/Melt_electrospinning

https://en.wikipedia.org/wiki/Taylor_cone

https://en.wikipedia.org/wiki/Spinneret_(polymers)

https://en.wikipedia.org/wiki/Tissue_engineering#Electrospinning

https://en.wikipedia.org/wiki/Polydioxanone

https://en.wikipedia.org/wiki/Electrospray

https://en.wikipedia.org/wiki/Polymer_nanocomposite#Bio-hybrid_nanofibres_by_electrospinning

https://en.wikipedia.org/wiki/Aluminium_oxide_nanoparticle

https://en.wikipedia.org/wiki/Nano-scaffold

https://en.wikipedia.org/wiki/Dielectric_barrier_discharge

https://en.wikipedia.org/wiki/Aggregate_(composite)

https://en.wikipedia.org/wiki/Field_electron_emission

https://en.wikipedia.org/wiki/Bacteriophage

https://en.wikipedia.org/wiki/Characteristic_X-ray

https://en.wikipedia.org/wiki/Flame_ionization_detector

https://en.wikipedia.org/wiki/Photon_upconversion

https://en.wikipedia.org/wiki/Bremsstrahlung

https://en.wikipedia.org/wiki/Forbidden_mechanism

https://en.wikipedia.org/wiki/Low-energy_ion_scattering

https://en.wikipedia.org/wiki/Maser

https://en.wikipedia.org/wiki/Neutron_generator#Ion_sources

https://en.wikipedia.org/wiki/Thermal_ionization

https://en.wikipedia.org/wiki/Particle-induced_gamma_emission

https://en.wikipedia.org/wiki/Helium_hydride_ion

https://en.wikipedia.org/wiki/Hydrogen_spectral_series

https://en.wikipedia.org/wiki/Trihydrogen_cation

https://en.wikipedia.org/wiki/Erwin_Wilhelm_Müller

https://en.wikipedia.org/wiki/Fluorophore

https://en.wikipedia.org/wiki/Vacuum_arc

https://en.wikipedia.org/wiki/Homogeneous_broadening

https://en.wikipedia.org/wiki/Gallium-68_generator

https://en.wikipedia.org/wiki/Upconverting_nanoparticles

https://en.wikipedia.org/wiki/Electron_ionization

https://en.wikipedia.org/wiki/Cherenkov_radiation#Emission_angle

ionization, thermal energy electrostatics electron melt air drag neutron drag plasma

dry thrust dessican vaccume

ion hydrag

https://en.wikipedia.org/wiki/Resonance_ionization

https://en.wikipedia.org/wiki/Self-ionization_of_water

https://en.wikipedia.org/wiki/Townsend_discharge

https://en.wikipedia.org/wiki/oxyanion_hole

https://en.wikipedia.org/wiki/Avalanche_breakdown

https://en.wikipedia.org/wiki/Electron_avalanche

https://en.wikipedia.org/wiki/Impact_ionization

https://en.wikipedia.org/wiki/Electrical_breakdown

https://en.wikipedia.org/wiki/Chain_reaction

https://en.wikipedia.org/wiki/Electronegativity

https://en.wikipedia.org/wiki/Magnetic_pressure

https://en.wikipedia.org/wiki/Tangential_and_normal_components

Spinors were introduced in geometry by Élie Cartan in 1913.[1][d] In the 1920s physicists discovered that spinors are essential to describe the intrinsic angular momentum, or "spin", of the electron and other subatomic particles.[e]

https://en.wikipedia.org/wiki/Spinor

missing atom, ion, emission, ionization , electron melt, melt , etc.. 21dop

https://en.wikipedia.org/wiki/Tunnel_ionization

https://en.wikipedia.org/wiki/Degree_of_ionization

https://en.wikipedia.org/wiki/Inductive_effect

https://en.wikipedia.org/wiki/Ion_source

https://en.wikipedia.org/wiki/Grand_canonical_ensemble

https://en.wikipedia.org/wiki/Fusion_bonded_epoxy_coating

Electron-beam welding (EBW) is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined. The workpieces melt and flow together as the kinetic energy of the electrons is transformed into heat upon impact. EBW is often performed under vacuumconditions to prevent dissipation of the electron beam.

Electrons are elementary particles possessing a mass m = 9.1 · 10⁻³¹ kg and a negative electrical charge e = 1.6 · 10⁻¹⁹ C. They exist either bound to an atomic nucleus, as conduction electrons in the atomic lattice of metals, or as free electrons in vacuum.

https://en.wikipedia.org/wiki/Electron-beam_welding

https://en.wikipedia.org/wiki/Induction_furnace

https://en.wikipedia.org/wiki/Nucleic_acid_thermodynamics

https://en.wikipedia.org/wiki/Fusion_welding

https://en.wikipedia.org/wiki/Plate_tectonics#Magnetic_striping

An amorphous metal transformer (AMT) is a type of energy efficient transformer found on electric grids.^[1] The magnetic core of this transformer is made with a ferromagnetic amorphous metal. The typical material (Metglas) is an alloy of iron with boron, silicon, and phosphorus in the form of thin (e.g. 25 µm) foils rapidly cooled from melt. These materials have high magnetic susceptibility, very low coercivity and high electrical resistance. The high resistance and thin foils lead to low losses by eddy currents when subjected to alternating magnetic fields. On the downside amorphous alloys have a lower saturation induction and often a higher magnetostriction compared to conventional crystalline iron-silicon electrical steel.^[2]

https://en.wikipedia.org/wiki/Amorphous_metal_transformer

Seen in some magnetic materials, saturation is the state reached when an increase in applied external magnetic field H cannot increase the magnetization of the material further, so the total magnetic flux density Bmore or less levels off. (Though, magnetization continues to increase very slowly with the field due to paramagnetism.) Saturation is a characteristic of ferromagnetic and ferrimagnetic materials, such as iron, nickel, cobalt and their alloys. Different ferromagnetic materials have different saturation levels.

https://en.wikipedia.org/wiki/Saturation_(magnetic)

A saturable reactor in electrical engineering is a special form of inductor where the magnetic core can be deliberately saturated by a direct electric current in a control winding. Once saturated, the inductance of the saturable reactor drops dramatically.^[1] This decreases inductive reactance and allows increased flow of the alternating current (AC).

https://en.wikipedia.org/wiki/Saturable_reactor

Ring and Ball Apparatus is used to determine the softening point of bitumen, waxes, LDPE, HDPE/PP blend granules, rosin and solid hydrocarbonresins.^[1] The apparatus was first designed way back in the 1910s while ASTM adopted a test method in 1916. This instrument is ideally used for materials having softening point in the range of 30 °C to 157 °C.^[2]^[3]^[4]

Components[edit]

Two brass rings.
Two steel balls.
Two ball guides to hold the balls in position.
A Support to hold the rings, balls and thermometer in position
A Glass beaker
Thermometer
Hot plate
Magnetic stirrer
Glycerol or water as heating bath

Procedure[edit]

The solid sample is taken in a Petri dish and melted by heating it on a standard hot plate. The bubble free liquefied sample is poured from the Petri dish and cast into the ring. The brass shouldered rings in this apparatus have 6.4 mm depth. The cast sample in the ring is kept undisturbed for one hour to solidify. Excess material is removed with hot knife. The ring is set with the ball on top with ball guides on the grooved plate within the heating bath. As the temperature rises, the balls begin to sink through the rings carrying a portion of the softened sample with it. The temperature at which the steel balls touch the bottom plate determines the softening point in degrees celsius.^[5]^[6] The bottom plate has a distance of 25 mm from the rings.^[7]

https://en.wikipedia.org/wiki/Ring_and_Ball_Apparatus

Metglas is a thin amorphous metal alloy ribbon produced by using rapid solidification process of approximately 1,000,000 °C/s (1,800,000 °F/s; 1,000,000 K/s). This rapid solidification creates unique ferromagnetic properties that allows the ribbon to be magnetized and de-magnetized quickly and effectively with very low core losses of approximately 5 mW/kg^[1] at 60 Hz and a maximum relative permeability of approximately 1,000,000.^[2]

https://en.wikipedia.org/wiki/Metglas

Fluxgate magnetometer[edit]

A uniaxial fluxgate magnetometer

A fluxgate compass/inclinometer

Basic principles of a fluxgate magnetometer

The fluxgate magnetometer was invented by H. Aschenbrenner and G. Goubau in 1936.^[19]^[20]^: 4 A team at Gulf Research Laboratories led by Victor Vacquier developed airborne fluxgate magnetometers to detect submarines during World War II and after the war confirmed the theory of plate tectonics by using them to measure shifts in the magnetic patterns on the sea floor.^[21]

A fluxgate magnetometer consists of a small magnetically susceptible core wrapped by two coils of wire. An alternating electric current is passed through one coil, driving the core through an alternating cycle of magnetic saturation; i.e., magnetised, unmagnetised, inversely magnetised, unmagnetised, magnetised, and so forth. This constantly changing field induces an electric current in the second coil, and this output current is measured by a detector. In a magnetically neutral background, the input and output currents match. However, when the core is exposed to a background field, it is more easily saturated in alignment with that field and less easily saturated in opposition to it. Hence the alternating magnetic field, and the induced output current, are out of step with the input current. The extent to which this is the case depends on the strength of the background magnetic field. Often, the current in the output coil is integrated, yielding an output analog voltage proportional to the magnetic field.

A wide variety of sensors are currently available and used to measure magnetic fields. Fluxgate compassesand gradiometers measure the direction and magnitude of magnetic fields. Fluxgates are affordable, rugged and compact with miniaturization recently advancing to the point of complete sensor solutions in the form of IC chips, including examples from both academia ^[22] and industry.^[23] This, plus their typically low power consumption makes them ideal for a variety of sensing applications. Gradiometers are commonly used for archaeological prospecting and unexploded ordnance (UXO) detection such as the German military's popular Foerster.^[24]

The typical fluxgate magnetometer consists of a "sense" (secondary) coil surrounding an inner "drive" (primary) coil that is closely wound around a highly permeable core material, such as mu-metal or permalloy. An alternating current is applied to the drive winding, which drives the core in a continuous repeating cycle of saturation and unsaturation. To an external field, the core is alternately weakly permeable and highly permeable. The core is often a toroidally wrapped ring or a pair of linear elements whose drive windings are each wound in opposing directions. Such closed flux paths minimise coupling between the drive and sense windings. In the presence of an external magnetic field, with the core in a highly permeable state, such a field is locally attracted or gated (hence the name fluxgate) through the sense winding. When the core is weakly permeable, the external field is less attracted. This continuous gating of the external field in and out of the sense winding induces a signal in the sense winding, whose principal frequency is twice that of the drive frequency, and whose strength and phase orientation vary directly with the external-field magnitude and polarity.

There are additional factors that affect the size of the resultant signal. These factors include the number of turns in the sense winding, magnetic permeability of the core, sensor geometry, and the gated flux rate of change with respect to time.

Phase synchronous detection is used to extract these harmonic signals from the sense winding and convert them into a DC voltage proportional to the external magnetic field. Active current feedback may also be employed, such that the sense winding is driven to counteract the external field. In such cases, the feedback current varies linearly with the external magnetic field and is used as the basis for measurement. This helps to counter inherent non-linearity between the applied external field strength and the flux gated through the sense winding.

SQUID magnetometer[edit]

SQUIDs, or superconducting quantum interference devices, measure extremely small changes in magnetic fields. They are very sensitive vector magnetometers, with noise levels as low as 3 fT Hz^−½ in commercial instruments and 0.4 fT Hz^−½ in experimental devices. Many liquid-helium-cooled commercial SQUIDs achieve a flat noise spectrum from near DC (less than 1 Hz) to tens of kilohertz, making such devices ideal for time-domain biomagnetic signal measurements. SERF atomic magnetometers demonstrated in laboratories so far reach competitive noise floor but in relatively small frequency ranges.

SQUID magnetometers require cooling with liquid helium (4.2 K) or liquid nitrogen (77 K) to operate, hence the packaging requirements to use them are rather stringent both from a thermal-mechanical as well as magnetic standpoint. SQUID magnetometers are most commonly used to measure the magnetic fields produced by laboratory samples, also for brain or heart activity (magnetoencephalography and magnetocardiography, respectively). Geophysical surveys use SQUIDs from time to time, but the logistics of cooling the SQUID are much more complicated than other magnetometers that operate at room temperature.

Spin-exchange relaxation-free (SERF) atomic magnetometers[edit]

At sufficiently high atomic density, extremely high sensitivity can be achieved. Spin-exchange-relaxation-free (SERF) atomic magnetometers containing potassium, caesium, or rubidium vapor operate similarly to the caesium magnetometers described above, yet can reach sensitivities lower than 1 fT Hz^−½. The SERF magnetometers only operate in small magnetic fields. The Earth's field is about 50 µT; SERF magnetometers operate in fields less than 0.5 µT.

Large volume detectors have achieved a sensitivity of 200 aT Hz^−½.^[25] This technology has greater sensitivity per unit volume than SQUIDdetectors.^[26] The technology can also produce very small magnetometers that may in the future replace coils for detecting changing magnetic fields.^{[citation needed]} This technology may produce a magnetic sensor that has all of its input and output signals in the form of light on fiber-optic cables.^[27] This lets the magnetic measurement be made near high electrical voltages.

Calibration of magnetometers[edit]

The calibration of magnetometers is usually performed by means of coils which are supplied by an electrical current to create a magnetic field. It allows to characterize the sensitivity of the magnetometer (in terms of V/T). In many applications the homogeneity of the calibration coil is an important feature. For this reason, coils like Helmholtz coils are commonly used either in a single axis or a three axis configuration. For demanding applications a high homogeneity magnetic field is mandatory, in such cases magnetic field calibration can be performed using a Maxwell coil, cosine coils,^[28] or calibration in the highly homogenous Earth's magnetic field.

https://en.wikipedia.org/wiki/Magnetometer#Fluxgate_magnetometer

https://en.wikipedia.org/wiki/Colloid_vibration_current

https://en.wikipedia.org/wiki/ion_drag

https://en.wikipedia.org/wiki/ion_vibration

https://en.wikipedia.org/wiki/Electrical_mobility

https://en.wikipedia.org/wiki/Electron_hole

Physics[edit]

Electrical resistance, the measure of the degree to which a conductor opposes an electric current through that conductor
Friction
- Drag (physics) ("air resistance"), fluid or gas forces opposing motion and flow
Geological resistance, a measure of how well minerals resist erosive factors
- Hydraulic conductivity, the ease with which water can move through pore spaces or fractures in soil or rock
Hardness, in materials science
Thermal shock resistance, a measure of resistance of a material to temperature jumps.
Thermal resistance, a measure of difficulty of heat transfer through a substance

Thermal conductivity, how well heat is conducted through a substance
Thermal resistance in electronics, heat considerations in electronics design

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.^[2] There are several types of friction:

Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic frictionbetween moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities (see Figure 1).

https://en.wikipedia.org/wiki/Friction

https://en.wikipedia.org/wiki/Hardness

https://en.wikipedia.org/wiki/Drag_(physics)

https://en.wikipedia.org/wiki/Induction_plasma

https://en.wikipedia.org/wiki/Induction_coil

https://en.wikipedia.org/wiki/Electrodynamic_suspension

https://en.wikipedia.org/wiki/Samarium–cobalt_magnet

https://en.wikipedia.org/wiki/State_of_matter#Magnetically_ordered

https://en.wikipedia.org/wiki/Emulsion

https://en.wikipedia.org/wiki/Cathode-ray_tube#Magnetic_deflection

https://en.wikipedia.org/wiki/Stellarator#Magnetic_confinement

https://en.wikipedia.org/wiki/Condensed_matter_physics#External_magnetic_fields

https://en.wikipedia.org/wiki/Glass

https://en.wikipedia.org/wiki/Zone_melting

https://en.wikipedia.org/wiki/Circulator

https://en.wikipedia.org/wiki/Transmission_line

https://en.wikipedia.org/wiki/Planar_transmission_line

https://en.wikipedia.org/wiki/Magnetic_field#Magnetic_field_lines

https://en.wikipedia.org/wiki/Vacuum_permeability

https://en.wikipedia.org/wiki/Centimetre–gram–second_system_of_units

https://en.wikipedia.org/wiki/Barye

https://en.wikipedia.org/wiki/Shear_stress

https://en.wikipedia.org/wiki/Statcoulomb

Amperian loop model

The Amperian loop model

A current loop (ring) that goes into the page at the x and comes out at the dot produces a

B

-field (lines). As the radius of the current loop shrinks, the fields produced become identical to an abstract "magnetostatic dipole" (represented by an arrow pointing to the right).

In the model developed by Ampere, the elementary magnetic dipole that makes up all magnets is a sufficiently small Amperian loop of current I. The dipole moment of this loop is $m = IA$ where $A$ is the area of the loop.

These magnetic dipoles produce a magnetic $B$ -field.

The magnetic field of a magnetic dipole is depicted in the figure. From outside, the ideal magnetic dipole is identical to that of an ideal electric dipole of the same strength. Unlike the electric dipole, a magnetic dipole is properly modeled as a current loop having a current $I$ and an area $a$ . Such a current loop has a magnetic moment of:

m=Ia, \,

where the direction of $m$ is perpendicular to the area of the loop and depends on the direction of the current using the right-hand rule. An ideal magnetic dipole is modeled as a real magnetic dipole whose area $a$ has been reduced to zero and its current $I$ increased to infinity such that the product $m = Ia$ is finite. This model clarifies the connection between angular momentum and magnetic moment, which is the basis of the Einstein–de Haas effect rotation by magnetization and its inverse, the Barnett effect or magnetization by rotation.^[24] Rotating the loop faster (in the same direction) increases the current and therefore the magnetic moment, for example.

https://en.wikipedia.org/wiki/Magnetic_field#Magnetic_field_lines

In physics and mechanics, torque is the rotational equivalent of linear force.^[1] It is also referred to as the moment, moment of force, rotational force or turning effect, depending on the field of study. The concept originated with the studies by Archimedes of the usage of levers. Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object around a specific axis. Another definition of torque is the product of the magnitude of the force and the perpendicular distance of the line of action of a force from the axis of rotation. The symbol for torque is typically ${\boldsymbol {\tau }}$ or $τ$ , the lowercase Greek letter tau. When being referred to as moment of force, it is commonly denoted by $M$ .

In three dimensions, the torque is a pseudovector; for point particles, it is given by the cross product of the position vector (distance vector) and the force vector. The magnitude of torque of a rigid body depends on three quantities: the force applied, the lever arm vector^[2] connecting the point about which the torque is being measured to the point of force application, and the angle between the force and lever arm vectors. In symbols:

{\boldsymbol {\tau }}=\mathbf {r} \times \mathbf {F} \,\!

\tau =\|\mathbf {r} \|\,\|\mathbf {F} \|\sin \theta \,\!

where

{\boldsymbol {\tau }}

is the torque vector and

\tau

is the magnitude of the torque,

\mathbf {r}

is the position vector (a vector from the point about which the torque is being measured to the point where the force is applied),

\mathbf {F}

is the force vector,

\times

denotes the cross product, which produces a vector that is perpendicular to both

r

and

F

following the right-hand rule,

\theta

is the angle between the force vector and the lever arm vector.

The SI unit for torque is the newton-metre (N⋅m). For more on the units of torque, see § Units.

https://en.wikipedia.org/wiki/Torque

Remanence or remanent magnetization or residual magnetism is the magnetization left behind in a ferromagnetic material (such as iron) after an external magnetic field is removed.^[1] Colloquially, when a magnet is "magnetized" it has remanence.^[2] The remanence of magnetic materials provides the magnetic memory in magnetic storage devices, and is used as a source of information on the past Earth's magnetic field in paleomagnetism. The word remanence is from remanent + -ence, meaning "that which remains".^[3]

The equivalent term residual magnetization is generally used in engineering applications. In transformers, electric motors and generators a large residual magnetization is not desirable (see also electrical steel) as it is an unwanted contamination, for example a magnetization remaining in an electromagnet after the current in the coil is turned off. Where it is unwanted, it can be removed by degaussing.

Sometimes the term retentivity is used for remanence measured in units of magnetic flux density.^[4]

https://en.wikipedia.org/wiki/Remanence

https://en.wikipedia.org/wiki/Magnetic_moment#Effects_of_an_external_magnetic_field

https://en.wikipedia.org/wiki/Magnetic_field

https://en.wikipedia.org/wiki/Conservative_vector_field

Levitation melting[edit]

In the 1950s, a technique was developed where small quantities of metal were levitated and melted by a magnetic field of a few tens of kHz. The coil was a metal pipe, allowing coolant to be circulated through it. The overall form was generally conical, with a flat top. This permitted an inert atmosphere to be employed, and was commercially successful.^[1]

Linear induction motor[edit]

The field from a linear motor generates currents in an aluminum or copper sheet that creates lift forces as well as propulsion.

Eric Laithwaite and colleagues took the Bedford levitator, and by stages developed and improved it.

First they made the levitator longer along one axis, and were able to make a levitator that was neutrally stable along one axis, and stable along all other axes.

Further development included replacing the single phase energising current with a linear induction motor which combined levitation and thrust.

Later "traverse-flux" systems at his Imperial College laboratory, such as Magnetic river avoided most of the problems of needing to have long, thick iron backing plates when having very long poles, by closing the flux path laterally by arranging the two opposite long poles side by side. They were also able to break the levitator primary into convenient sections which made it easier to build and transport.^[2]

Null flux[edit]

Null flux systems work by having coils that are exposed to a magnetic field, but are wound in figure of 8 and similar configurations such that when there is relative movement between the magnet and coils, but centered, no current flows since the potential cancels out. When they are displaced off-center, current flows and a strong field is generated by the coil which tends to restore the spacing.

These schemes were proposed by Powell and Danby in the 1960s, and they suggested that superconducting magnets could be used to generate the high magnetic pressure needed.

https://en.wikipedia.org/wiki/Electrodynamic_suspension#Levitation_melting

HOLIDAYZ2021

HMV: Tigger and Friends - I Wanna Scare Myself - Halloween Music Video Crossover 2019

Lettuce (Lactuca sativa) is an annual plant of the daisy family, Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, such as soups, sandwiches and wraps; it can also be grilled.^[3] One variety, the celtuce(asparagus lettuce), is grown for its stems, which are eaten either raw or cooked. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. Europe and North America originally dominated the market for lettuce, but by the late 20th century the consumption of lettuce had spread throughout the world. World production of lettuce and chicory for 2017 was 27 million tonnes, 56% of which came from China.^[4]

Lettuce was originally farmed by the ancient Egyptians, who transformed it from a plant whose seeds were used to create oil into an important food crop raised for its succulent leaves and oil-rich seeds. Lettuce spread to the Greeks and Romans; the latter gave it the name lactuca, from which the English lettuce is derived. By 50 AD, many types were described, and lettuce appeared often in medieval writings, including several herbals. The 16th through 18th centuries saw the development of many varieties in Europe, and by the mid-18th century cultivars were described that can still be found in gardens.

Generally grown as a hardy annual, lettuce is easily cultivated, although it requires relatively low temperatures to prevent it from flowering quickly. It can be plagued by numerous nutrient deficiencies, as well as insect and mammal pests, and fungal and bacterial diseases. L. sativa crosses easily within the species and with some other species within the genus Lactuca. Although this trait can be a problem to home gardeners who attempt to save seeds, biologists have used it to broaden the gene pool of cultivated lettuce varieties.

Lettuce is a rich source of vitamin K and vitamin A, and a moderate source of folate and iron. Contaminated lettuce is often a source of bacterial, viral, and parasitic outbreaks in humans, including E. coli and Salmonella.

https://en.wikipedia.org/wiki/Lettuce

https://en.wikipedia.org/wiki/Glossary_of_botanical_terms#sensu_amplo

Non-vascular plants are plants without a vascular system consisting of xylem and phloem. Instead, they may possess simpler tissues that have specialized functions for the internal transport of water.

Non-vascular plants include two distantly related groups:

Bryophytes, an informal group that taxonomists now treat as three separate land-plant divisions, namely: Bryophyta (mosses), Marchantiophyta (liverworts), and Anthocerotophyta (hornworts). In all bryophytes, the primary plants are the haploid gametophytes, with the only diploid portion being the attached sporophyte, consisting of a stalk and sporangium. Because these plants lack lignified water-conducting tissues, they can't become as tall as most vascular plants.
Algae, especially the green algae. The algae consist of several unrelated groups. Only the groups included in the Viridiplantae are still considered relatives of land plants.^[1]^: 6^[2]

These groups are sometimes called "lower plants", referring to their status as the earliest plant groups to evolve, but the usage is imprecise, since both groups are polyphyletic and may be used to include vascular cryptogams, such as the ferns and fern allies that reproduce using spores. Non-vascular plants are often among the first species to move into new and inhospitable territories, along with prokaryotes and protists, and thus function as pioneer species.

Non-vascular plants do not have a wide variety of specialized tissue types.^{[citation needed]} Mosses and leafy liverworts have structures called phyllids that resemble leaves, but only consist of single sheets of cells with no internal air spaces no cuticle or stomata and no xylem or phloem. Consequently, phyllids are unable to control the rate of water loss from their tissues and are said to be poikilohydric. Some liverworts, such as Marchantia have a cuticle and the sporophytes of mosses have both cuticles and stomata, which were important in the evolution of land plants.^[3]

All land plants have a life cycle with an alternation of generations between a diploid sporophyte and a haploid gametophyte, but in all non-vascular land plants the gametophyte generation is dominant. In these plants, the sporophytes grow from and are dependent on gametophytes for taking in water and mineral nutrients and for provision of photosynthate, the products of photosynthesis.

https://en.wikipedia.org/wiki/Non-vascular_plant

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showvte

Classification of Archaeplastida or Plantae s.l.

Categories: Plants

Cellulose is an organic compound with the formula (C
6H
10O
5)
n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units.^[3]^[4] Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms.^[5] Cellulose is the most abundant organic polymer on Earth.^[6] The cellulose content of cotton fiber is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%.^[7]^[8]^[9]

Cellulose is mainly used to produce paperboard and paper. Smaller quantities are converted into a wide variety of derivative products such as cellophane and rayon. Conversion of cellulose from energy cropsinto biofuels such as cellulosic ethanol is under development as a renewable fuel source. Cellulose for industrial use is mainly obtained from wood pulp and cotton.^[6]

Some animals, particularly ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts, such as Trichonympha. In human nutrition, cellulose is a non-digestible constituent of insoluble dietary fiber...

History[edit]

Cellulose was discovered in 1838 by the French chemist Anselme Payen, who isolated it from plant matter and determined its chemical formula.^[3]^[10]^[11] Cellulose was used to produce the first successful thermoplastic polymer, celluloid, by Hyatt Manufacturing Company in 1870. Production of rayon ("artificial silk") from cellulose began in the 1890s and cellophane was invented in 1912. Hermann Staudingerdetermined the polymer structure of cellulose in 1920. The compound was first chemically synthesized (without the use of any biologically derived enzymes) in 1992, by Kobayashi and Shoda.^[12]

External links[edit]

"Cellulose" . Encyclopædia Britannica. 5 (11th ed.). 1911.
Structure and morphology of cellulose by Serge Pérez and William Mackie, CERMAV-CNRS
Cellulose, by Martin Chaplin, London South Bank University
Clear description of a cellulose assay method at the Cotton Fiber Biosciences unit of the USDA.
Cellulose films could provide flapping wings and cheap artificial muscles for robots – TechnologyReview.com

https://en.wikipedia.org/wiki/Cellulose

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