Quality factor

The open circuit voltage of an SBSC is also directly proportional to this quantity (see equation 28). It has been shown in Section 2.3 that n increases with interfacial oxide thickness and the density of interface states according to equation 21 

Fabre has reported titanium p-type silicon MIS SBSCs in which the value of n was as high as 3.8. Such high values of n could not be explained by equation 37 and were most probably due to the presence of a thicker interfacial oxide which caused the forward current to become tunnel limited. Such high values of n do not necessarily contribute to a greater conversion efficiency since the thickness of the interfacial layer also causes a reduction in the short circuit current density. 

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A microwave pulse from a tunable oscillator is injected into the cavity by an anteima, and creates a coherent superposition of rotational states. In the absence of collisions, this superposition emits a free-mduction decay signal, which is detected with an anteima-coupled microwave mixer similar to those used in molecular astrophysics. The data are collected in the time domain and Fourier transfomied to yield the spectrum whose bandwidth is detemimed by the quality factor of the cavity. Hence, such instruments are called Fourier transfomi microwave (FTMW) spectrometers (or Flygare-Balle spectrometers, after the inventors). FTMW instruments are extraordinarily sensitive, and can be used to examine a wide range of stable molecules as well as highly transient or reactive species such as hydrogen-bonded or refractory clusters [29, 30]. 

The sinc fiinction describes the best possible case, with often a much stronger frequency dependence of power output delivered at the probe-head. (It should be noted here that other excitation schemes are possible such as adiabatic passage [9] and stochastic excitation [fO] but these are only infrequently applied.) The excitation/recording of the NMR signal is further complicated as the pulse is then fed into the probe circuit which itself has a frequency response. As a result, a broad line will not only experience non-unifonn irradiation but also the intensity detected per spin at different frequency offsets will depend on this probe response, which depends on the quality factor (0. The quality factor is a measure of the sharpness of the resonance of the probe circuit and one definition is the resonance frequency/haltwidth of the resonance response of the circuit (also = a L/R where L is the inductance and R is the probe resistance). Flence, the width of the frequency response decreases as Q increases so that, typically, for a 2 of 100, the haltwidth of the frequency response at 100 MFIz is about 1 MFIz. Flence, direct FT-piilse observation of broad spectral lines becomes impractical with pulse teclmiques for linewidths greater than 200 kFIz. For a great majority of... 

The sharpness of the frequency response of a resonant system is conunonly described by a factor of merit, called the quality factor, Q=v/Av. It may be obtained from a measurement of the frill width at half maxuuum Av, of the resonator frequency response curve obtained from a frequency sweep covering the resonance. The sensitivity of a system (proportional to the inverse of tlie minimum detectable number of paramagnetic centres in an EPR cavity) critically depends on the quality factor... 

K Casting quality factor n Number of items Dimensionless Dimensionless... 

E, Joint quality factor P Design gauge pressure kPa Ibf/im... 

S = basic allowable stress for materials, excluding casting, joint, or structural-grade quahty factors E = quahty factor. The quahty factor E is one or the product of more than one of the following quahty factors casting quality factor Ec, joint quahty factor Ej (see Fig. 10-164), and structural-grade quahty factor E, of 0.92. 

FIG. 10-164 Longitudinal and spiral-weld joint factor E. NOTE It is not permitted to increase tlie joint quality factor by additional examination for joints 1, 2, and 4a. (EjLtracted from ANSI B31.3—19S0, with petmission of the publisher, theAmetican Society of Mechanical Engineets, New York.)... 

A quality factor of 92 percent is included for structural grade. 

SE values shown in tliis table for welded pipe include the joint quality factor E, for the longitudinal weld as required by Fig. 10-164 and, when applicable, the structural-grade quality factor Es of 0.92. For some code computations, particularly with regard to expansion, dexibility, structural attachments, supports, and restraints, the longihidinal-joint quality factor E, need not be considered. To determine the allowable stress S for use in code computations not ntdizing the joint quality factor E, divide the value SF shown in tliis table by the longitudinal-joint quality factor E, tabulated in Fig. 10-164. 

Stress values shown include the casting quality factor shown in this table. Higlier stress values can be used if specijJ inspection is accomplished. 

The SE values in Table 10-49 are equal to the basic allowable stresses in tension S multiplied by a quality factor E (see subsection Pressure Design of Metallic Components Wall Tliick-ness"). The design stress values for bolting materials are equal to die basic allowable stresses S. The stress values in shear shall be 0.80 times the allowable stresses in tension derived from tabulated values in Table 10-49 adjusted when applicable in accordance widi Note 13. 8tress values in bearing shall be twice those in shear. 

The part stress analysis prediction section contains failure rate models for a broad variety of parts used in electronic equipment. This method includes the effects of part quality factors and environmental factors. The tabulated values of the base failure rate are "cut off" at the design temperature and stress of the part. 

B = distributor quality factor C = vapor capacity factor... 

So in order to minimize this noise one possibility is to work at low temperature, this is what is done in the Japanese TAMA project. The other solution is to use optical materials with a low value of the loss angle, or equivalently a high quality factor. 

W Pilnik and A.G. J. Voragen In J.J. Jen (Ed.) Quality factors of fruits and vegetables. Chemistry and Technology. ACS American Chemical Society Symposium series 405 (1989) 250. 

In QSAR equations, n is the number of data points, r is the correlation coefficient between observed values of the dependent and the values predicted from the equation, is the square of the correlation coefficient and represents the goodness of fit, is the cross-validated (a measure of the quality of the QSAR model), and s is the standard deviation. The cross-validated (q ) is obtained by using leave-one-out (LOO) procedure [33]. Q is the quality factor (quality ratio), where Q = r/s. Chance correlation, due to the excessive number of parameters (which increases the r and s values also), can. 

Quality factor or quality ratio (Q) The high values of Q (2.259-14.646) for these QSAR models suggest that the high predictive power for these models as well as no over-fitting. 

Quality Factor (Q)—The linear-energy-transfer-dependent factor by which absorbed doses are multiplied to obtain (for radiation protection purposes) a quantity that expresses - on a common scale for all ionizing radiation - the approximate biological effectiveness of the absorbed dose. 

Relative Biological Effectiveness (RBE)—The RBE is a factor used to compare the biological effectiveness of absorbed radiation doses (i.e., rad) due to different types of ionizing radiation. More specifically, it is the experimentally determined ratio of an absorbed dose of a radiation in question to the absorbed dose of a reference radiation (typically 60Co gamma rays or 200 keV x rays) required to produce an identical biological effect in a particular experimental organism or tissue (see Quality Factor). 

Rem—A unit of dose equivalent that is used in the regulatory, administrative, and engineering design aspects of radiation safety practice. The dose equivalent in rem is numerically equal to the absorbed dose in rad multiplied by the quality factor (1 rem is equal to 0.01 sievert). 

Sievert (Sv)—The SI unit of any of the quantities expressed as dose equivalent. The dose equivalent in sieverts is equal to the absorbed dose, in gray, multiplied by the quality factor (1 sievert equals 100 rem). 

Dose equivalent or rem is a special radiation protection quantity that is used, for administrative and radiation safety purposes only, to express the absorbed dose in a manner which considers the difference in biological effectiveness of various kinds of ionizing radiation. The ICRU has defined the dose equivalent, H, as the product of the absorbed dose, D, and the quality factor, Q, at the point of interest in biological tissue. This relationship is expressed as H = D x Q. The dose equivalent concept is applicable only to doses that are not great enough to produce biomedical effects. 

Table D-3. Quality Factors (Q) and Absorbed Dose Equivalencies...

Tvne of radiation Quality factor (O) Absorbed dose equal to a unit dose equivalent ... 

RBE is used to denote the experimentally determined ratio of the absorbed dose from one radiation type to the absorbed dose of a reference radiation required to produce an identical biologic effect under the same conditions. Gamma rays from cobalt-60 and 200-250 keV x-rays have been used as reference standards. The term RBE has been widely used in experimental radiobiology, and the term quality factor used in calculations of dose equivalents for radiation safety purposes (ICRP 1977 NCRP 1971 UNSCEAR 1982). RBE applies only to a specific biological end point, in a specific exposure, under specific conditions to a specific species. There are no generally accepted values of RBE. 

The texture of ice cream is an important quality factor to consumers. What is the chemical basis for the gritty or sandy-like texture that detracts from ice cream s pleasant taste ... 

Each point in the phase diagram in Fig. 8.8 corresponds to a certain value of a and b, i.e., it represents the possible chemical composition of a molecular population. Variable a forms the horizontal axis, (1 +a) being the number of monomer types. The b axis represents the quality factor of the polymer catalysis. The transition region contains those populations which can have both ordered and disordered... 

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