Particle passage

Natural porous media may be consolidated (solids with holes in them), or they may consist of unconsolidated, discrete particles. Passages through the beds may be characterized by the properties of porosity, permeability, tortuosity, and connectivity. The flow of underground water and the production of natural gas and crude oil, for example, are affected by these characteristics. The theory and properties of such structures is described, for instance, in the book of Dullien (Porous Media, Fluid Transport and Pore Structure, Academic, New York, 1979). A few examples of porosity and permeability are in Table 6.9. Permeability is the proportionality constant k in the flow equation u = (k/p) dP/dL. 

The photons emitted by the fluor are detected by a phototube-photomultiplier system. The lifetime of the p particle passage, solvent excitation, and eventual photon emission from fluors is short... 

Natural porous media may be consolidated (solids with holes in them), or they may consist of unconsolidated, discrete particles. Passages through the beds may be characterized by the properties of porosity, permeability, tortuosity, and... 

The FDA defines sterilizing filters as those that have pore-size ratings of 0.22 pm or smaller and relates this to a microbiological particle passage test using Pseudomonas (Brevundimonas) diminuta ... 

It is essential that the microbiological particle passage test is performed as part of the development of new sterile formulations. Because of its very specialized nature, the test is normally performed only by the filter manufacturers, who then provide limits for secondary physical tests (e.g., bubble point, pressure decay, forward flow, etc.), which can be applied to verify the pore size rating and integrity of the membrane filters. 

Segre G, Silberberg A (1962) Behaviour of macroscopic rigid spheres in Poiseuille flow. Part 1. Determination of the local concentration by statistical analysis of particle passages through crossed hght beams. J Fluid Mech 14 115-135... 

The results in Figure 3 indicate that particle passage or retention in ground-water aquifers can be more dependent on chemical factors than physical one. ... 

Whal is meant by the pore size ratings of commercially available membranes Pore size ratings of commercially available membranes are not indices of maximum pore opening diameters obtained from direct microscopic measurement or by particle passage methods. Ratings are almost always determined by indirect means based on theoretical considerations and on nondestructive test technology. 

The performance characteristics of the membrane, flow rate and applied differential pressure, may also affect microbial particle passage experiments. The rate at which a liquid is able to pass tiirough a membrane is defined by the equation... 

The main factors that affect the particle passage through sieve aperture are the method of sieve shaking, the ratio of open area of sieve to total area, particle size distribution, the number of particles on the sieve (sieve loading), and the dimension and shape of the particle. Friability and cohesiveness of solid particles can also affect the sieving operation. Difficulty can also arise with high aspect ratio particles (i.e., needle-shaped or flaky particles). 

The gap is generally higher for large particles to physically allow adequate particle passage for suitable particle density in the spray region and ensure efficient coating. 

The combined results of the two non-adiabatic effects just described yields a net displacement across the F-surfaces, being of the order of one Larmor radius a in the field for a complete particle passage through a support region. The corresponding random-walk process of ions and electrons leads to an equivalent am-bipolar diffusion process across the F-surfaces. The ratio between the corresponding loss rate and the thermonuclear power production Pj)-p has been estimated to ... 

Types of optical fiber probes are presented in Table 5, and some examples of probes are shown in Fig. 16. In the case of the reflection-type optical flber probe, the volume from which the probe can detect the in form a -tion depends on flber conflguration. The intensity distribution of reflected light as a function of the distance between a fiber tip and a flat surface is shown in Fig. 17. The size of the core of the optical fiber should be selected depending on the maximum diameter of particles being investigated. If individual particle passages are to be detected, the fiber core diameter should be less than or equal to the particle diameter. On the other hand, if only the passage of solids or the solids concentration is to be detected, the fiber diameter of a... 

Figure 21 Doppler signals corresponding to a single particle passage received by different photomultipliers, (van den Moortel et al., 1997.) (With permission of Elsevier Science)...

Figure 22 Schematic of a light reflection type space filter (a), tracer particle passage (b), and wave pattern of output signals from light reflection type space filter in a gas-liquid system (c). (Kamiwano and Saito, 1984.) (Reproduced with permission of the American Institute of Chemical Engineers. Copyright 1984 AIChE. All rights reserved.)...

Ventilating passages minimize entrance of rain, snow, and airborne particles. Passages are less than Ya in (2 cm) in diameter. 

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