Source, sink

Action of Vacuum on Spacecraft Materials. For service beyond the atmosphere, the vacuum environment allows materials to evaporate or decompose under the action of various forces encountered (1,18,19). These forces include the photons from the sun, charged particles from solar wind, and dust. The action of space environment on materials and spacecraft can be simulated by a source—sink relationship in a vacuum environment. Thus, for example, the lifetime of a solar panel in space operation may be tested (see Photovoltaic cells). 

This simulation can be achieved in terms of a source—sink relationship. Rather than use the gas concentration around the test object as a target parameter, the test object can be surrounded by a sink of ca 2-7T soHd angle. The solar panel is then maintained at its maximum operating temperature and irradiated by appropriate fluxes, such as those of photons. Molecules leaving the solar panel strike the sink and are not likely to come back to the panel. If some molecules return to the panel, proper instmmentation can determine this return as well as their departure rates from the panel as a function of location. The system may be considered in terms of sets of probabiUties associated with rates of change on surfaces and in bulk materials. 

Non-Black-Surface Enclosures In the following discussion we are concerned with enclosures containing gray sources and sinks, radiatively adiabatic surfaces, and no absorbing gas. The calculation of interchange between a source and a sink under conditions involving successive multiple reflections from other source-sink surfaces in the... 

Many furnace problems are adequately handled by dividing the enclosure into but two source-sink zones Ai and A9 and any number of no-flux zones A, A .. . . For this case Eq, (5-130) yields... 

For the two-source-sink-zone system to which Eq, (5-136) applies, Eq, (5-137) simplifies to... 

The motor/generator is modeled as an energy source/sink limited by its specific design capabilities. As a generator, it will absorb all excess power available while holding speed constant (synchronous) as long as it is electrically connected to the utility grid. 

On the source-sink mapping diagram, sources are represented by shaded circles and sinks are represented by hollow circles. Typically, process constraints limit the range of pollutant composition and load that each sink can accept. ITie intersection of these two bands provides a zone of acceptable conqKisition and load for recycle. If a source (e.g., source a) lies within this zone, it can be directly recycled to tiie sink (e.g., sink S). Moreover, sources b and c can be mixed using the lever-arm principle to create a mixed stream that can be recycled to sink S. 

The source-sink mapping diagram can also be used to determine the extent of interception needed. If a source lies to the right of a sink, it can be intercepted to render it within the band of acceptable recycle. The problem of simultaneously... 

Figure 4.2 Identification of lEcycle oppoitunities using source-sink mapping diagram (from E)-Halwagi and Spriggs, 1996)...

Let us first segregate the two sources forming the feed to the incinerator. As can be seen from the source-sink mapping diagram (Fig. 9.20), the gaseous emission from the ammonium nitrate process (R2) is within the acceptable zone for the incinerator. Therefore, it should not be mixed with R] then separated. Instead, the ammonia content of Ri should be reduced to 0.10 wt% then mixed with R2 to provide an acceptable feed to the incinerator as shown by Fig. 9.20. The task of removing ammonia from Rj to from 1.10 wt% to 0.10 wt% is identical to the case study solved in Section 9.3. Hence, the solution presented in Fig. 9.18 can be used. 

Figure 9.20 A gaseous source-sink mapping diagram for (he ammonium nitrate example...

The third term on the left side of the equation has significance in reactive systems only. It is used with a positive sign when material is produced as a net result of all chemical reactions a negative sign must precede this term if material is consumed by chemical reactions. The former situation corresponds to a source and the latter to a sink for the material under consideration. Since the total mass of reactants always equals the total mass of products in a chemical reaction, it is clear that the reaction (source/sink) term (R should appear explicitly in the equation for component material balances only. The overall material balance, which is equivalent to the algebraic sum of all of the component balance equations, will not contain any (R term. 

While understanding chemical reactions is a necessary first step, integrating knowledge of reactions with knowledge of sources, sinks, and transport of chemicals is also necessary. In addition to this "hard science understanding, there is also the need to incorporate social science understanding of human use or abuse of our environmental resources. 

Box, E. O. (1988). Estimating the seasonal carbon source-sink geography of a natural, steady-state terrestrial biosphere, /. Appl. Meteorol. 17,1109-1124. 

Before stating the main results, it will be sensible to clarify a physical sense of the function u(x), which solves problem (1) subject to the conditions [u] = 0 and [kii ] = — Qq (/ — x) kg = g at the point x =. Here q stands for the capacity of a point heat source (sink) at the point X =. Being dependent on x, the quantity q varies very widely. Specifically, q —+ 00 as X — 5 0. Thus, the physical reason for the convergence of scheme (2) is that the heat balance (the conservation law of heat) is... 

JUNCTION-1,..., JUNCTION-15, PIPE-1,. PIPE-42, HYDROCARBON-SOURCE, SINK-1, SINK-2, HYDROGEN-SOURCE, NATURAL-GAS-SOURCE. CARBON-TETRACHLORIDE-SOURCE,... 

PIPE-31 PIPE-33, HYDROCARBON-SOURCE, SINK-1, SINK-2]... 

In the other examples, the electrode materials are not involved in the reactions chemically, but constitute the source [sink] of electrons. Such electrodes are called nonconsumable. The term inert electrodes sometimes used is unfortunate insofar as the electrode itself is by no means inert rather, it has a strong catalytic effect on the electrode reaction. For reactions occurring at such electrodes, the terms oxidation- reduction... 

Johnson DW, Lindberg SE. 1995. Sources, sinks, and cycling of mercury in forested ecosystems. Water Air Soil Pollut 80 1069-1077. 

Frankenberger, Jr., and Muhammad Arshad Handbook of Weed Management Systems, edited by Albert E. Smith Soil Sampling, Preparation, and Analysis, Kim H. Tan Soil Erosion, Conservation, and Rehabilitation, edited by Menachem Agassi Plant Roots The Hidden Half, Second Edition, Revised and Expanded, edited by Yoav Waisel, Amram Eshel, and Uzi Kafkafi Photoassimilate Distribution in Plants and Crops Source-Sink Relationships, edited by Eli Zamski and Arthur A. Schaffer Mass Spectrometry of Soils, edited by Thomas W. Boutton and Shinichi Yamasaki... 

J.C. Murrell and D.P. Kelley, Microbiology of Trace Gases. Source, Sinks and Global Change Processes, Springer, Berlin, 1996. 

Other than the virtual momentum force Fp, a virtual mass source/sink should also be applied to the particle surface to satisfy the continuity for the control volume containing the particle surface or the particle (Kim et al., 2001). The mass source can be calculated by... 

MacLeod, W.D., Jr. L.S. Ramos, A.J. Friedman, D.G. Burrows, P.G. Prohaska, D.L. Fisher, and D.W. Brown. 1981. Analysis of Residual Chlorinated Hydrocarbons, Aromatic Hydrocarbons, and Related Compounds in Selected Sources, Sinks, and Biota of the New York Bight. U.S. NOAA, Tech. Memor. OMPA-6.128 pp. 

Although there exists a good understanding of the chemistry of phosphorus in soil-water systems, the hydrologic pathways linking spatially variable phosphorus sources, sinks, temporary storages, and transport processes in landscapes are less... 

The rate enhancement observed for submonolayer Cu deposits may relate to an enhanced activity of the strained Cu film for this reaction due to its altered geometric and electronic properties. Alternatively, amechansim whereby the two metals cooperatively catalyze different steps of the reaction may account for the activity promotion. For example, dissociative Hj adsorption on bulk Cu is unfavorable due to an activation barrier of approximately 5 kcal/mol . In the combined Cu/Ru system, Ru may function as an atomic hydrogen source/sink via spillover to/from neighboring Cu. A kinetically controlled spillover of Hj from Ru to Cu, discuss above, is consistent with an observed optimum reaction rate at an intermediate Cu coverage. 

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