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Subject: Music

This US group was formed in Los Angeles, California, in 1978 by Steve Allen (guitar, vocals) and Ron Flynt (bass, vocals), two expatriate musicians from Tulsa, Oklahoma. Drummer Mike Gallo ...

sound pressure level

sound pressure level   Quick reference

A Dictionary of Electronics and Electrical Engineering (5 ed.)

Reference type:
Subject Reference
Current Version:
2018
Subject:
Science and technology, Engineering and Technology
Length:
60 words
Illustration(s):
1

...pressure level ( SPL ) The root-mean-square (r.m.s.) pressure of a sound wave at a particular instant ( P actual ), usually expressed in decibels (dBSPL) with respect to the average threshold of hearing at 1 kilohertz ( P ref ) of 20 micropascal: ...

eutectic mixture

eutectic mixture   Quick reference

A Dictionary of Chemical Engineering

Reference type:
Subject Reference
Current Version:
2014
Subject:
Science and technology, Engineering and Technology
Length:
85 words
Illustration(s):
1

...of the substances. The eutectic point is the lowest temperature at which a solution can exist and that three condensed phases can co-exist ( see Fig. 20 ). Low melting-point alloys are usually eutectic mixtures. For example, the freezing point of pure lead and pure tin are 327°C and 232°C, respectively, whereas a mixture with 62 per cent lead (soft solder) has a eutectic point of 183°C. Fig. 20 Eutectic point ...

API gravity

API gravity   Quick reference

A Dictionary of Chemical Engineering

Reference type:
Subject Reference
Current Version:
2014
Subject:
Science and technology, Engineering and Technology
Length:
57 words
Illustration(s):
1

...API gravity A measure of the density of petroleum oils used in the US and related to specific gravity : The specific gravity and API gravity refer to the weight per unit volume at 15.6ºC (60ºF). Most crude oils range between 20 and 45 o API. ...

Crimp and Bruges’ formula

Crimp and Bruges’ formula   Quick reference

A Dictionary of Construction, Surveying and Civil Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Science and technology, Engineering and Technology
Length:
65 words
Illustration(s):
1

...and Bruges’ formula Used to calculate flow in sewers: v = 56 m 0 . 67 i where v = velocity (m/sec), m = hydraulic mean depth (m) and i = the slope of the sewer. It is now considered that the equation yields conservative estimates (of the order of 20%) for the value of v when compared to experimental data. See also Barnes formula...

stokes

stokes   Quick reference

A Dictionary of Chemical Engineering

Reference type:
Subject Reference
Current Version:
2014
Subject:
Science and technology, Engineering and Technology
Length:
74 words
Illustration(s):
1

... of a fluid expressed as the ratio of the viscosity, μ , in poise divided by the density, ρ , in grams per cubic centimetre: The units of centistokes, cSt, are more commonly used where 1 cSt is equal to 10 −6 m 2 s −1 . The kinematic viscosity of water is exactly 1 cSt at 20.2 º C. ...

acoustic wave

acoustic wave   Quick reference

A Dictionary of Electronics and Electrical Engineering (5 ed.)

Reference type:
Subject Reference
Current Version:
2018
Subject:
Science and technology, Engineering and Technology
Length:
406 words
Illustration(s):
2

...of the wave, and the wave therefore consists of compressions and rarefactions of the material. The term ‘sound wave’ is sometimes used specifically for those waves with a frequency falling within the audible range of the human ear, i.e. from about 20 hertz to 20 kilohertz. Waves of frequency greater than about 20 kHz are ultrasonic waves. In a crystalline solid an acoustic wave is transmitted as a result of the displacement of the lattice points about their mean position, and the modes of propagation are constrained by the interatomic forces active between...

spectral blackbody emissive power

spectral blackbody emissive power   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
219 words
Illustration(s):
1

.../ k = 1.439 × 10 4 μ m . K , c 0 = 299 792 458 m/s is the speed of light in vacuo, k = 1.380 648 52 × 10 −23 J/K is the Boltzmann constant , and h = 6.626 070 040 × 10 −34 J.s is Planck’s constant (minor adjustments to the values of these constants were made effective 20 May 2019). This equation for E B λ ‎ is valid for a surface in vacuum or a gas. For another medium, it needs to be modified by replacing C 1 with C 1 / n 2 where n is the refractive index for the medium. https://www.bipm.org./utils/common/pdf/si-brochure-draft-2016b.pdf ...

A screw thread (DRAFT)

A screw thread (DRAFT)   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
982 words
Illustration(s):
4

...( M threads ) being shown in M threads [ISO 724:1993 ‘ISO general purpose metric screw threads – Basic dimensions’.] Standard metric threads are designated by the nominal major diameter and the pitch , so that a 20 mm diameter coarse metric thread having a pitch of 2.5 mm becomes M20×2.5 and the corresponding fine thread version is M20×1.5. Now-obsolete V-shaped thread ( V-thread ) systems include British Association (BA) , British Standard Whitworth coarse (BSW) and fine (BSF) threads. Some Imperial threads are still in use, such as the British...

electron microscope

electron microscope   Quick reference

A Dictionary of Electronics and Electrical Engineering (5 ed.)

Reference type:
Subject Reference
Current Version:
2018
Subject:
Science and technology, Engineering and Technology
Length:
336 words
Illustration(s):
2

...and other properties of the sample. These electrons are converted, by means of an electron detector, scintillator , and photomultiplier , into a highly amplified signal that is used for intensity modulation of the beam of the display cathode-ray tube. The resolution is about 10–20 nm. Different forms of these two types have been developed. The scanning-transmission electron microscope ( STEM ) combines the high resolution of the transmission instrument with the perspective image of the scanning type. The scanning-tunnelling microscope ( STM ) and the ...

extractive distillation

extractive distillation   Quick reference

A Dictionary of Chemical Engineering

Reference type:
Subject Reference
Current Version:
2014
Subject:
Science and technology, Engineering and Technology
Length:
259 words
Illustration(s):
1

...component to leave at the top of the column ( see Fig. 21 ). Extractive distillation is more widely used than azeotropic distillation since there is a wider choice of agent and there is no need for close matching of volatilities. Azeotropic entrainers must usually boil within 5–20°C of the other components. There is also a lower heat requirement since the solvent is not vaporized. There is also a wider choice of operating conditions. The solvent/feed ratio, for example, is not critical, unlike an entrainer/feed ratio, and there is easier recovery of the...

ductile–brittle transition temperature

ductile–brittle transition temperature   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
320 words
Illustration(s):
1

...temperature ( FATT ), the fracture surface is 50% cleavage and 50% ductile. The temperature at which C V is midway between the upper and lower shelf values is similar. In the selection of many low-strength steels, a ductility transition temperature ( DTT ) defined by C V = 20 J is used. Experience shows that brittle fracture does not initiate above that temperature. The DBTT and the energy absorbed by ductile fracture in the upper shelf region are sensitive to changes in the microstructure. For example, the former is increased and the latter decreased...

Mohr’s stress circle

Mohr’s stress circle   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
319 words
Illustration(s):
5

...2 centred on the σ ‎ -axis at ½ ( σ x + σ y ) , called Mohr’s stress circle. In terms of principal stresses σ ‎ 1 and σ ‎ 2 , σ θ = [ ( σ 1 + σ 2 ) + ( σ 1 − σ 2 ) c o s 2 θ ] / 2 and τ θ = ( σ 1 − σ 2 ) sin 2 θ / 2 , which plots as a circle centred at ( σ ‎ 1 + σ ‎ 2 )/2,0 having radius ( σ ‎ 1 − σ ‎ 2 )/2. For loading in three dimensions, there are three Mohr’s circles having diameters ( σ ‎ 1 − σ ‎ 2 ), ( σ ‎ 2 − σ ‎ 3 ) and ( σ ‎ 1 − σ ‎ 3 ) where σ ‎ 1 , σ ‎ 2 , and σ ‎ 3 are the principal stresses . Mohr’s stress...

jar test

jar test   Quick reference

A Dictionary of Construction, Surveying and Civil Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Science and technology, Engineering and Technology
Length:
274 words
Illustration(s):
1

...then placed on the jar test equipment, where paddles are inserted into the beakers. The paddles are initially rotated for a short time at high speeds (say, 200 rpm for 60 seconds) to ensure uniform dispersion of the coagulant. After which the speed of the paddles is reduced (say, 20 rpm for 15–30 minutes) to aid the formation of floc . The paddles are then stopped and the samples are allowed to settle (say, for another 15–30 minutes). The actual timescale is site-specific, but would typically be in the order of periods stated. Too little coagulant and the...

screw

screw   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
1,105 words
Illustration(s):
4

...60° threads ( M threads ) being shown in [ISO 724:1993 ‘ISO general purpose metric screw threads – Basic dimensions’.] Standard metric threads are designated by the nominal major diameter and the pitch , so that a 20-mm diameter coarse metric thread having a pitch of 2.5 mm becomes M20×2.5 and the corresponding fine thread version is M20×1.5. Now-obsolete V-shaped thread ( V-thread ) systems include British Association ( BA ), British Standard Whitworth coarse ( BSW ) and fine ( BSF ) threads. Some Imperial threads are still in use, such as the ...

radiation damage

radiation damage   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
1,491 words
Illustration(s):
1

...create more energetic recoils, and so on. This displacement cascade continues until none of the displaced atoms has energy > E d . This occurs in less than 1 ps (10 −12 s) after the primary recoil event and in a zone less than 10–20 nm in diameter. A 10-keV cascade produces an average of 30 vacancies and 30 SIAs, and a 20-keV cascade produces twice as many. Higher-energy cascades tend to divide into distinct sub-cascades. Some point defects created in a cascade cluster with their own kind in the cascade zone to form small dislocation loops; others remain...

magnetron

magnetron   Quick reference

A Dictionary of Electronics and Electrical Engineering (5 ed.)

Reference type:
Subject Reference
Current Version:
2018
Subject:
Science and technology, Engineering and Technology
Length:
924 words
Illustration(s):
4

...mm wavelength waves with a power output during the pulse of 750 kilowatts. It requires an anode voltage of 31 kilovolts and magnetic flux density of 0.28 tesla. Most magnetrons are fixed-frequency magnetrons but tunable magnetrons have been produced in which a variation of 10–20% in the frequency is achieved by means of plungers moved into the resonators from one end. http://www.explainthatstuff.com/how-magnetrons-work.html A short introduction to magnetrons ...

superconductivity

superconductivity   Quick reference

A Dictionary of Electronics and Electrical Engineering (5 ed.)

Reference type:
Subject Reference
Current Version:
2018
Subject:
Science and technology, Engineering and Technology
Length:
746 words
Illustration(s):
1

...magnets. Niobium-tin (Nb 3 Sn) for example can produce a magnetic field of about 12 tesla at 4.2 kelvin, i.e. at the boiling point of liquid helium. Other transition metal compounds such as Nb 3 Ge have transition temperatures at around the boiling point of liquid hydrogen (20 K). Such compounds fall into the Al5 series, i.e. they have a crystallographic structure similar to beta-tungsten. High-temperature superconductivity with transition temperatures of 90 K or above has been demonstrated using complex ceramic oxides that contain rare earth elements...

toothed gearing

toothed gearing   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
1,724 words
Illustration(s):
7

...point. The first and last points of contact, A and B, of mating teeth are where the addenda circles cut I 1 I 2 . The path of contact AB is divided into AP, the arc of approach , and PB, the arc of recess . ϕ ‎ is a design choice, but standard gears usually have ϕ ‎ equal to 20 or 25°, while 14½° was once common. As the shape of the involute depends solely on the radius of the base circle, the distance between the centres of spur gears may be changed within limits without affecting the motion transmitted, except that the pressure angle is altered. Since a...

welding

welding   Quick reference

A Dictionary of Mechanical Engineering (2 ed.)

Reference type:
Subject Reference
Current Version:
2019
Subject:
Science and technology, Engineering and Technology
Length:
1,017 words
Illustration(s):
2

...large (about the radius of the welding rod). An arc of length between 2 and 10 mm is struck with a potential difference of 30–75 volts, giving an impinging power density of 10–100 MW/m 2 . However, up to 10% of metal is lost because of evaporation , condensing as dust ; and 10–20% of filler is lost by spatter. In gas-flame and arc welding, protection against deleterious gas entrainment in joints is achieved either by (i) flooding with an inert gas (argon is most common, as nitrogen is not sufficiently inert in the plasma) that minimizes the amount of...

solar cell

solar cell   Quick reference

A Dictionary of Energy Science

Reference type:
Subject Reference
Current Version:
2017
Subject:
Science and technology, Engineering and Technology, Environmental Science
Length:
205 words
Illustration(s):
1

...the series resistance and the back surface recombination, respectively, of the cell. The band gap in silicon (1.1 eV) determines the maximum efficiency and the open-circuit voltage V OC . Good commercial silicon cells have V OC ~0.7 V and 20 per cent of the solar energy is converted to electrical energy, i.e. a 20 per cent efficient cell. See also multijunction solar cell ; photovoltaics ; schockley-queisser limit . Silicon solar...

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