Source geometry

The geometry of the contaminant source can be compact or linear. The source geometry affects the hood geometry round, rectangular, or slot. 

This approach is much easier to use than the first, but may give less accurate results since it assumes an average or typical value for the heat transfer coefficient for all heated source geometries. 

Evaporation from an alloy source largely avoids the problems of source geometry which may be encountered in simultaneous evaporation from separate pure metal sources. The success of the method depends on the relative vapor pressures of the component metals in the alloy source because one component metal with a substantially higher vapor pressure will evaporate preferentially. The alloy film will then be rich in the more volatile component compared with the composition of the source and may also be stratified into layers of different composition. Evaporation from alloy sources is discussed in detail by Dushman (43) and Holland (44) on the basis of Raoult s law, and it is possible to predict which metal pairs... 

With due regard to the lateral variations in composition which can arise as a consequence of source geometry and positioning (discussed in Section II), it is vise to analyze the alloy film at a number of representative points. For example, if a catalytic reaction was carried out over an alloy film deposited inside a spherical vessel maintained at a constant temperature over its entire area, then the mean alloy composition (and the uniformity of composition) is required. A convenient procedure is to cut glass reaction vessels carefully into pieces at the end of the experiment and to determine the composition by X-ray fluorescence analysis of a number of representative pieces. Compositions of Pd-Ag alloy films (40) determined at 12 representative parts of a spherical vessel from the intensities of the AgK 12 and PdKau fluorescent X-ray emissions are shown in Table V mean compositions are listed in the first column. (The Pd and Ag sources were separate short concentric spirals.) In other applications of evaporated alloy films to adsorption and catalytic studies, as good or better uniformity of composition was achieved. Analyses of five sections of a cylindrical... 

By employing a laser for the photoionization (not to be confused with laser desorption/ ionization, where a laser is irradiating a surface, see Section 2.1.21) both sensitivity and selectivity are considerably enhanced. In 1970 the first mass spectrometric analysis of laser photoionized molecular species, namely H2, was performed [54]. Two years later selective two-step photoionization was used to ionize mbidium [55]. Multiphoton ionization mass spectrometry (MPI-MS) was demonstrated in the late 1970s [56—58]. The combination of tunable lasers and MS into a multidimensional analysis tool proved to be a very useful way to investigate excitation and dissociation processes, as well as to obtain mass spectrometric data [59-62]. Because of the pulsed nature of most MPI sources TOF analyzers are preferred, but in combination with continuous wave lasers quadrupole analyzers have been utilized [63]. MPI is performed on species already in the gas phase. The analyte delivery system depends on the application and can be, for example, a GC interface, thermal evaporation from a surface, secondary neutrals from a particle impact event (see Section 2.1.18), or molecular beams that are introduced through a spray interface. There is a multitude of different source geometries. 

Introduction Gas explosions depend on a large number of parameters, including temperature, pressure, gas composition, ignition source, geometry of surroundings, turbulence in the gas, mixing, time before ignition, and so forth. Thus, gas explosions are difficult to characterize and predict. 

Xu (1994) also provided (estimatel/i/u vedues for 0.08, 0.3 and 1.0 MeV for a variety of point sources at various locations and distances from the body, which are not included in this Table. The values for the Xu94 preferred algorithm for 10 different point-source geometries ranged from a low of 0.80 to a high of 2.22. 

Define potential scenario, chemical properties, source geometry, and atmospheric conditions, which can affect the width of the cloud, the effect of obstacles on the cloud and the impact of the water sprays themselves ... 

Abstract The objective of this chapter is to present some recent developments on nonaque-ous phase liquid (NAPL) pool dissolution in water saturated subsurface formations. Closed form analytical solutions for transient contaminant transport resulting from the dissolution of a single component NAPL pool in three-dimensional, homogeneous porous media are presented for various shapes of source geometries. The effect of aquifer anisotropy and heterogeneity as well as the presence of dissolved humic substances on mass transfer from a NAPL pool is discussed. Furthermore, correlations,based on numerical simulations as well as available experimental data, describing the rate of interface mass transfer from single component NAPL pools in saturated subsurface formations are presented. 

As mentioned previously, a given y-radiation-source geometry will supply free radicals at a constant rate for vinyl monomer poly-... 

Phases+ Changes of variables Energy source Geometry Surface material Facility medium Operate mode... 

Profio and Doiron [33] have derived equations for various source geometries including planar (used to treat skin tumors), cylindrical (to treat within a bronchus) and spherical (used within the bladder). 

Chemiluminescence.—It has been suggested that problems which occur in the determination of yields of bio- and chemi-luminescence may be due to the sample cell. Errors of 25% may be caused by reflection and refraction from interfaces, and, consequently, frosted containers and point-source geometries were recommended. Several authors have concentrated on the use of sensitizers for the enhancement of chemiluminescence. The heavy-atom effect was found to operate in the energy transfer from enzyme-generated acetone to xanthene dyes. 9,10-Diphenylanthracene (9,10-DP A) has been suggested to be a poor singlet counter for chemiluminescence as some triplet states were also counted. In another report, 9,10-dibromoanthracene was found to be a more effective enhancer, when compared with 9,10-DPA, for chemiluminescence from a cyclic peroxide. Luminol chemiluminescence was employed in the analysis of Cr" ions in sea-water. Enhancement with bromide ions enabled detection limits of 3.3 X 10 m to be achieved. 

Monomers with low molecular weights will diffuse into the wood more rapidly than polymers such as PEG. In a second phase, their in situ radiation curing will form wood consolidants that are much stronger than PEG. However, this method requires very heavy irradiation equipment, which is usually available only in nuclear research centers. The irradiation cell dimensions and the 7-source geometry limit the size of the artifacts. For mainly these reasons, the radiation process was applied in very few institutions and in most cases only at the experimental level. The Nucleart Laboratory, which routinely conserves waterlogged wood by this technique, is located in the Grenoble Nuclear Research Center of the French Atomic Energy Commission. 

Overwater, R.M.W., Bode, P., De Goeij, J.J.M., 1993. Gamma-ray spectroscopy of voluminous sources. Corrections for source geometry and self-attenuation. Nucl. Instrum. Methods A324, 209-218. 

FiGxmE 14.9. Central (A) and annular (B) source geometries used with portable radioisotopic x-ray analyzers. 

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