Coefficient of transmission

When plotting the standard curve it is customary to assign a transmission of 100 per cent to the blank solution (reagent solution plus water) this represents zero concentration of the constituent. It may be mentioned that some coloured solutions have an appreciable temperature coefficient of transmission, and the temperature of the determination should not differ appreciably from that at which the calibration curve was prepared. 

COEFFICIENT OF TRANSMISSIBILITY The rate of flow of water in gallons per day through a vertical strip of the aquifer 1 ft (0.3 m) wide, under a unit hydraulic gradient. 

As explained in Appendix 9C, the double-sum form of E( ) expresses its all-to-all nature. The initial and final states of the transmission process are enumerated by the indices a and a, respectively, that characterize the electronic states in directions perpendicular to the transmission process, and Ea E) is the coefficient of transmission between these states. 

It may be mentioned that some colour solution have appreciable temperature coefficient of transmission, and the temperature of determination should not differ appreciably finm that at which calibration curve was prepared. 

The molecular mobility in the polymers was determined by dielectric studies. Polymer films 300—500 pm thick cast between glass plates at room temperature were used. Dielectric measiu ements were made using the E8-4 ac bridge within a broad temperature range. The superimposed frequency of the external electric field was 1 kHz. The dependence of the coefficient of transmission of the cured polyester resin on the OP-10 content was determined using the FEC-56M photoelectric calorimeter. 

Figure A3.6.11. Viscosity dependence of transmission coefficient of the rate of cyclohexane chair-boat inversion in liquid solution (data from [100]).

Friction Materials. PhenoHc friction materials are made from mol ding compounds developed to meet the extraordinary demands required by friction elements in the transportation industries. Friction materials are used for brake linings, clutch facings, and transmission bands. A moderately high coefficient of friction, which is temperature-independent, is needed. In addition, the material must be high in strength, low in wear and abrasion, and resistant to moisture and hydrauHc fluids. 

The properties of high quaUty vitreous sihca that determine its uses iaclude high chemical resistance, low coefficient of thermal expansion (5.5 X 10 /° C), high thermal shock resistance, high electrical resistivity, and high optical transmission, especially ia the ultraviolet. Bulk vitreous sihca is difficult to work because of the absence of network-modifyiag ions present ia common glass formulations. An extensive review of the properties and stmcture of vitreous sihca is available (72). 

Nitriding permits increased tooth loading. The amount of increased capacity is not exactly known, but a 20% increase in load at 10,000-12,000 rpm has proven reliable. A further advantage of the nitrided coupling is that the coefficient of friction is lower than that for through-hardened parts. The heat from friction in the coupling decreases. More important, the transmission of axial forces is decreased by the reduced friction. 

The above are of course only some of the most common characteristics. Individual materials may have special properties such as photoconductivity, very low coefficient of friction to steel, high dielectric constant, high ultraviolet light transmission and so on. 

The most ubiquitous method of transmission spectroscopy, in which the amount of light passing through a sample is determined. Very often the influence of reflection and scattering is neglected and the ratio of incident and transmitted intensity ( / ) is linked to the absorption coefficient (a) and the sample thickness (d) by Lambert-Beer s law (see Eq. (9.11)). 

Cope, W.F. Ptvc. Inst. Mech. Engrs. 45 (1941) 99. The friction and heat transmission coefficients of rough pipes. 

Transmissivity is simply the coefficient of permeability, or the hydraulic conductivity (k), within the plane of the material multiplied by the thickness (T) of the material. Because the compressibility of some polymeric materials is very high, the thickness of the material needs to be taken into account. Darcy s law, expressed by the equation Q = kiA, is used to calculate the rate of flow, with transmissivity equal to kT and i equal to the hydraulic gradient (see Figure 26.22) ... 

Normal incidence transmission IRLD measurements are used to study thin films (typically 100 pm thickness and less, depending on the molar extinction coefficient of the bands) with in-plane uniaxial orientation. Two spectra are recorded sequentially with the radiation polarized parallel (p) and perpendicular (s) to the principal (machine) direction of the sample. The order parameter of the transition moment of the studied vibration is calculated from either the dichroic ratio (R — Ap/As) or the dichroic difference (AA = Ap—As) as ... 

Some simple rearrangement of Equation 3.1 leads to the concepts of transmission T = Io/1 and absorbance A = — log T, with the quantity s c l called the optical density. The choice of units here for the extinction coefficient (M-1 cm-1) is appropriate for measurement of the absorbance of a solution in the laboratory but not so appropriate for a distance Z of astronomical proportions. The two terms and c are contracted to form the absorption per centimetre, a, or, more conveniently (confusingly) in astronomy, per parsec. The intrinsic ability of a molecule or atom to absorb light is described by the extinction coefficient s, and this can be calculated directly from the wavefunction using quantum mechanics, although the calculation is hard. 

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