Critical issues

Finally, preliminary diagnostic evaluation criteria, based on preventive identification of critical areas of interest on the monitored item, spatial concentration of localized AE events as compared with average AE event density and evolution of local event concentration vs time and/or plant parameters, have been worked out and submitted to extensive testing under real operation conditions. Work on this very critical issue is still to be consohdated. 

Weldments subjected to corrosive attack over a period of time may crack adjacent to the weld seams if the residual stresses are not removed. Gas—tungsten arc welding and gas—metal arc welding ate recommended for joining magnesium, the former for thinner materials and the latter for thicker materials. Maintaining a protective atmosphere is a critical issue in welding these alloys. 

From the standpoint of commercialization of fuel ceU technologies, there are two challenges initial cost and reHable life. The initial selling price of the 200-kW PAFC power plant from IFC was about 3500/kW. A competitive price is projected to be about 1500/kW orless for the utiHty and commercial on-site markets. For transportation appHcations, cost is also a critical issue. The fuel ceU must compete with conventional mass-produced propulsion systems. Furthermore, it is not clear if the manufacturing cost per kilowatt of small fuel ceU systems can be lower than the cost of much larger units. The life of a fuel ceU stack must be five years minimum for utiHty appHcations, and reHable, maintenance-free operation must be achieved over this time period. The projection for the PAFC stack is a five year life, but reHable operation has yet to be demonstrated for this period. 

Occupational Health Safety Seven Critical Issues Oceanic Abstracts OIL... 

Wafer charging is becoming a critical issue as new MOS devices are designed with thinner (<10 mm) gate dielectrics. Lower energy implanters require optics that compensate for beam divergence which occurs at low energeries (32). 

Electrode Walls. Development of durable electrode wads, one of the most critical issues for MHD generators, has proceeded in two basic directions ceramic electrodes operating at very high surface temperatures (>2000 K) for use in channels operating with clean fuels such as natural gas, and cooled metal electrodes with surface temperatures in the range 500—800 K for channels operating with slag or ash-laden flows. 

In addition to the mobihty control characteristics of surfactants, critical issues in gas mobihty control processes are surfactant salinity tolerance, hydrolytic stabihty under reservoir conditions, surfactant propagation through the reservoir, and foam stabihty in the presence of cmde oil saturations. 

No external heat source is required. In all types of steelmaking that employ pig iron, which melts at temperatures well below low carbon steel, the heat balance between exothermic oxidation of elements, such as C, Si, and Mn, and the cooling provided by scrap or sometimes other endothermic coolants, such as iron ore, are critical issues. The numerical factors are well understood and are routinely contained in computer programs used by operators. If the balance is such that the temperature after blowing is too high, refractory consumption is increased significantly. 

Owing to the light and air sensitivity of the carotenoids and retinoids, sample handling is a critical issue. It is recommended to conduct extraction of these materials with peroxide-free solvents, to store biological samples at —70° C under argon and in the dark, to perform the analysis under yellow light, and to use reference compounds of high purity (57). 

A critical issue is the stabiUty of the hydride electrode in the cell environment. A number of hydride formulations have been developed. Table 5 shows hydride materials that are now the focus of attention. Most of these are Misch metal hydrides containing additions of cobalt, aluminum, or manganese. The hydrides are prepared by making melts of the formulations and then grinding to fine powers. The electrodes are prepared by pasting and or pressing the powders into metal screens or felt. The additives are reported to retard the formation of passive oxide films on the hydrides. 

Technical and Business Issues. In general, the successflil appHcation of any technology is dependent on both technical and business issues. For knowledge-based systems, six critical issues are problem identification, user acceptance, measurement of impact, appropriateness, feasibHity, and cost. 

Temperature Most industrial wastes tend to be on the warm side. For the most part, temperature is not a critical issue below 37° C... 

In some situations, a risk analysis (perhaps quantitative) may be of value in selecting from the options. Use of the risk analysis can reveal both critical equipment and critical procedures. Once the critical issues are identified, design to accommodate them. 

In the two typical shaft seal manufacturing processes shown in Fig. 2, the extrusion process is only required if the compression molding process is being used. There are basically two types of extruders in general use, the cold feed and the hot feed. In both cases their role is to produce the preforms for use with compression molding. The critical issues with the preform are the shape, the dimensions, and the weight. 

There are four critical issues required for all the molding processes listed previously, they are [6] ... 

Even where low nickel alloys are specified, corrosion, however limited, may lead to the release of other alloying components and the release of more radionuclides such as chromium51, cobalt58, iron59, and manganese54. Thus, materials selection remains a critical issue in nuclear plant SG design. 

PET recycling, research trends and critical issues in, 533-534 PET resin, 24... 

Spot size. The size of the LGS is a critical issue, since it dehnes the saturation effects of the laser and the power needed to reach a given system performance, and also the quality of the wavefront sensing. There is an optimum diameter of the projector, because, if the diameter is too small, the beam will be spread out by diffraction and if it is too large it will be distorted due to atmospheric turbulence. The optimum diameter is about 3ro, thus existing systems use projection telescopes with diameters in the range of 30-50 cm. 

Goldman LR. 1995. Case studies of environmental risks to children. Critical Issues for Children and Youths 5 27-33. 

Numerical accuracy and efficiency are critical issues for the DML model to be accepted in engineering applications. FFT-based algorithm has been introduced to speed up the computations, and attempts have been made to validate the model by comparing the results from the present DML model with those from other sources of numerical analyses and experiments. 

Example 62 If a manufacturing process involves two raw materials, each defined by three sets of specification limits, and four pieces of equipment with one control knob, then a complete validation protocol would ask for (Three settings Lo, Target, Hi) (2 materials 3 specs + 4 machines 1 control) = 3 = 59 000 experiments, even without repetitions. This product would never reach the market if one did not employ experience and scientific rationale to simplify development by testing only the presumed critical issues, say a total of three specification points for 3 = 27 experiments. 

From a toxicological point of view, the critical issue is how much of the toxic form of the chemical reaches the site of action. This will be determined by the interplay of the processes of uptake, distribution, metabolism, storage, and excretion. These processes will now be discussed in a little more detail. 

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