Be Realistic

Since the void fraction distribution is independently measurable, the only remaining adjustable parameters are the A, so when surface diffusion is negligible equations (8.23) provide a completely predictive flux model. Unfortunately the assumption that (a) is independent of a is unlikely to be realistic, since the proportion of dead end pores will usually increase rapidly with decreasing pore radius. 

From time to time during the programme, 1 shall break off from introducing new ideas and help you consolidate what you ve aheady learnt with some review problems. These are meant to be realistic problems showing why synthesis is important and should let you try out your growing skills. You can either do the review problems as you meet them or come back later and use them as revision material or combine both methods by doing one or two now and the rest later. These remarks apply to all the review problems and 1 won t repeat them each time. 

Wall Geometries. Rougher-than-rough waU geometries can reduce transmission probabUities in Knudsen flow by as much as 25% compared to the so-caUed rough-waU cosine reflection (34,35). For this and other reasons, conductance calculations that claim accuracy beyond a few percent may not be realistic. 

A failure modes and effects analysis delineates components, their interaction.s ith each other, and the effects of their failures on their system. A key element of fault tree analysis is the identification of related fault events that can contribute to the top event. For a quantitative evaluation, the failure modes must be clearly defined and related to a numerical database. Component failure modes should be realistically and consistently postulated within the context of system operational requirements and environmental factors. 

A type of time dependence that is available in most codes evaluates the exponential distribution at specified times. This is the constant failure rate - constant repair rate approximation ( Section 2.5.2). This may not be realistic as indicated by Figure 2.5-2 in which the failure rate is not constant. Furthermore, Lapides (1976) shows that repair rates are not constant but in many casc. appear to be lognormally distributed. 

The zone model has the following basic limitations 1) complex enclosure geometries cannot be addres.sed, 2) forced ventilation cannot be realistically modeled using simple unit models, 7 ) burning other combustibles remote from the initiating source are not modeled, and 4) siipprcssion activities are not included. 

Confidence limits for the conclusions cannot be expressed simply because of the complexity of hazard assessments. The estimation of uncertainties is itself a process subject to professional judgment. However, the team s estimates of probability are believed to be realistic, but may be pessimistic by a factor of perhaps two or three, but less than a factor of ten. Uncertainties also exist... 

The use of clearly defined target levels has become more and more important in industrial ventilation. The targets must be realistic and verifiable... 

We just cannot expect situations like golf clubs and tennis rackets for all consumer products because all products do not have those same built-in characteristics of the competitive edge. When we consider a car, we must be realistic and acknowledge that the car must have a price low enough for people to afford. Think back to the days of Henry Ford he made a car that could be sold for about 250, so that everyone could afford to have one. This affordability was the real beauty of his mass-production techniques. Everyone could afford to have a car, and then almost everyone did have one. In contrast, before Henry Ford, only the rich could afford an automobile. As soon as we get to the trade-off where composite materials will effectively compete in the automotive market place, we will see tremendously broader applications, but there are problems along the way. The manufacturing cost must be improved in order for those applications to ever come about. 

Human resources, whether in-house or retained by contract, cost money, and represent either a direct or an indirect investment. In lobbying for PSM resources, be realistic about the time you think the effort will require underestimating the level of effort can raise management s expectations beyond your ability to meet them. At the same time, estimates of staff required can t ignore prevailing company priorities for example, a request for five new staffers during a hiring freeze is unlikely to be favorably received. 

In setting schedules and deadlines, try to be realistic while maintaining your sense of urgency. Be sure to build in sufficient time for group meetings to evaluate progress to date. Also, remember to consult those most immediately affected (for example, people whose staff will be called on) by the plan, whose other priorities must be taken into account in scheduling. 

The pace at which this proceeds should be realistic, in view of the availability of technical and managerial resources. In many parts of the world your plants will be far from other company activities, and your ability to provide support from headquarters or from "sister" plants will be limited. 

The team should be realistic about the time required to see improvements in end-of-pipe measures in most cases the pilot project success will be measured on efficiency improvements and other in-process measures alone. In this case it is important to demonstrate that all PSM and ESH issues are being managed. You should consider having a management systems audit (validation) conducted by a group independent of the integration project team. This may be done in conjunction with the next scheduled audit. This may be a corporate or divisional audit function or a consultant engaged specifically for this task. 

When too many factors of safety are added to the true required design flows, excess margins may affect compressor stability. When the compressor manufacturer begins the design, therefore, unjustified excess capacity flows exist. Be realistic in regard to building in flexibility or capacity. 

Much of what has been said about budgets applies equally to the project program. It should be realistic from the outset - again independent professional advice should be sought. 

However, in reality this sometimes does not always work that way. If we are to be realistic, we must examine how machinery component failure modes appear and behave as a function of time. To understand this fully, we must concern ourselves with the concept of machinery component life. 

When testing for corrosion under heat-transfer conditions, the heat flux must be realistic. It is not good enough to merely reproduce the correct temperatures... 

The planning stage decides where the effort for energy economy should be concentrated and sets target figures for the amount of savings and the necessary implementation costs with payback periods. These assessments should be realistic and as accurate as possible. 

At the turn of the century, this situation partly changed. By economic selection, only those developments that were market-oriented survived. In addition, most commentators in the field such as the trade press realized that they had to change their attitude on reporting a proper outlook, i.e. what can be realistically expected in the coming years hence, euphoria changed to (sober) realism [242]. 

Similar ideas can be applied to formaldehyde oxidation. For bulk formaldehyde oxidation, we found predominant formic acid formation under current reaction conditions rather than CO2 formation. Hence, it cannot be ruled out, and may even be realistic, that formaldehyde is first oxidized to formic acid, which can subsequently be oxidized to CO2. The steady-state product distribution at 0.6 V is much more favorable for such a mechanism as in the case of methanol oxidation. On the other hand, because of the high efficiency of COad formation from formaldehyde, this process is likely to proceed directly from formaldehyde adsorption rather than via formation and re-adsorption of formic acid. Alternatively, the second oxygen can be introduced via formaldehyde hydration to methylene glycol, which could be further oxidized to formic acid and finally to CO2 (see the next paragraph). 

Soil properties A Soil texture (sand, silt, clay), organic matter/carbon content, and pH Stones, roots, and hardpans must be largely absent to allow representative sampling of soil profile Soil properties should appear uniform over test site Soil texture data should be available at time of site selection. Soil properties must match study purpose. This can be realistic use conditions, realistic worst-case or worst-case in terms of agrochemical mobility and persistence Must ensure that the majority of samples can be taken from the deepest sampling horizon. Information about sub-soils can be obtained from soil maps, test coring and on-site interviews... 

Table 2. Known inputs and outputs of U to the oceans. Units are 10 g yr or thousand tons per year. References are the most recent primary studies of that flux. Some other fluxes (e.g., groundwater input and input or removal at estuaries) are so poorly known that they cannot be realistically included. Significant uncertainty remains in most of the fluxes listed above so that, within these uncertainties, the U budget can be considered to be in balance.

For all the above studies, the cycle time used for rich and lean phase, 15 and 30 min, respectively, was long and far from being realistic. In addition to such long cycle studies, to get an estimate of the catalyst performance under realistic conditions, we have also done second type of studies known as short cycle studies. In these studies, the total cycle time was kept relatively short ( s) to simulate the actual exhaust conditions, and... 

The minimum DNB ratio is evaluated at the hottest fuel rod in the hottest flow channel of the core. The fluid conditions in the hottest flow channel of an open-channel PWR should be realistically evaluated by considering the cross-channel... 

The worst operating condition in a common design practice consists of overly conservative assumptions on the hot-channel input. These assumptions must be realistically evaluated in a subchannel analysis by the help of in-core instrumentation measurements. In the early subchannel analysis codes, the core inlet flow conditions and the axial power distribution were preselected off-line, and the most conservative values were used as inputs to the code calculations. In more recent, improved codes, the operating margin is calculated on-line, and the hot-channel power distributions are calculated by using ex-core neutron detector signals for core control. Thus the state parameters (e.g., core power, core inlet temper-... 

The photolysis and soil degradation constants must be realistic for the compound in question. Laboratory or field studies are usually needed to confirm these numbers. 

Choice of watershed must be realistic and the watershed should have pertinent crops on it. 

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