Worst case situation

The life of the product- access to the records will probably not be needed for some considerable time, possibly long after the contract has closed. On defense contracts the contractor has to keep records for up to 20 years and for product liability purposes, in the worst case situation (taking account of appeals), you could be asked to produce records up to 17 years after you made the product. 

In contrast, with composite materials, the materials utilization factor is rarely higher than 1.2 to 1.3. That is, only a maximum of 20-30% of the material is wasted with composite structures. Whereas obviously with a materials utilization factor for some metal parts of 15-25, the waste is 1500-2500% Those are not individually typical numbers, but are the worst cases in both situations, i.e., for metals and composite materiais. For metals, there are many, many operations for which the waste factor is very iow. And for composite materials there are also many situations where the waste factor is much lower than 20-30%. The point is that the worst-case situations are totaliy different for these two kinds of materials based on the way objects are inherently created with the two different types of materials. Composite materials are built up until the limits of the desired geometry are reached. At that point, the layup operation simpiy ceases. Composite materials and structures are fabricated in as ciose to the final configuration as possible, i.e., so-calied near-net shape. 

Another strategy would involve design of the reactor vessel for a pressure rating in excess of any likely emergency system pressure. This assumes we can adequately predict all possible worst case situations, which is doubtful. 

Risk assessors tend to build in additional uncertainty factors to avoid healthrelevant underestimates. This is partly done by using screening methods designed to look for worst case situations. Such worse case assumptions lead to intake estimates that exceed reality. For chemicals that present potential risks, more information is needed to allow more refined screening or even the most accurate estima-... 

The required flow rate can be calculated (1) directly from MTG or (2) on the basis of surface water inflow rate. To be conservative, all three calculations should be performed and the worst-case situation (e.g., that with the highest flow rate) used for the required flow rate. The various equations for determining the required flow rate or transmissivity appear below ... 

The chlorinated chemicals assessed do not have the same risk profile. For the more volatile chemicals the safety margins between the actual exposure and the level at which no effect on the environment would be expected is quite high. For more persistent chemicals there is a need to look to the environmental compartment where they can be accumulated (mainly in sediments and biota). For some of these chemicals the safety margin is quite low and in worst-case situations serious effects may occur. For the very persistent, bioaccumulative and toxic chemicals (like dioxins, PCBs and DDT), acceptable environmental concentrations are so low and difficult to control that the industry is committed to reducing as far as possible releases to the environment through application of Best Available Techniques (BAT), mainly with respect to dioxins. For other chemicals (PCBs, DDT), production has already been halted for some years. 

The conditions with the worst response value can be derived from the estimated effects. The worst-case situation is that combination of factor levels resulting in the worst result, e.g., the lowest resolution. The worst-case conditions are set using only the effects significant at... 

The data from the 2000 FSIS/USDA monitoring program (Table 12.4) present very similar results to those found in the 1998 data (USDA, 2000). For the sake of simplicity, the data presented show the violations and the upper 95% confidence limits. These data confirm the consistently low incidence of antibiotic and sulfonamide residues in animals grown for food. Even in the worst-case situation, the upper range of the violative incidence remains relatively low, usually less than 2%. There are some hot spots, namely in veal calves, hogs, and horses. Horses appear to be a special case because these animals are rarely used for food in the U.S. It may be that horses are treated with antibiotics or antimicrobials to ensure the animals or carcasses are in the best shape for marketing. 

There is little available or published evidence to indicate that the antibiotic and sulfonamide residue profiles of similar products not used for export would be different. Until data can be found that indicate otherwise, the only assumption consistent with data is that residue levels and incidences are similar throughout the parts of the world where reasonable regulatory practices exist. However, for areas where regulatory monitoring is not considered important there is no system for estimating extent of residues. It may be prudent to make a worst-case situation assumption for these areas, namely that there would be a high frequency residues in products of animal origin. 

Vermeire et al. (1999) stated that in the standard procedure for deriving acceptable limit values, various assessment factors are multiplied to obtain an overall assessment factor. However, multiplication of assessment factors implies a piling up of worst-case assumptions the probability of simultaneous occurrence of worst-case situations for the same chemical is smaller than the occurrence of a single worst-case situation. Therefore, the higher the number of extrapolation steps, the higher the level of conservatism. The piling up of worst-case assumptions can be avoided by using probability distributions (Section 5.11). 

Potentially serious consequences of a worst case situation may rule out conducting the operation. Usually, adequate means of avoiding the situation and coping with the consequences can be devised. These start with preventive measures, followed by corrective measures, then containment measures and, as a last resort, isolation techniques. Redundancy is essential for protection against reactive chemicals accidents. 

Examine the process in detail with the aid of appropriate flow diagrams, looking at upset conditions, delays which can occur, modes of failure, worst case situations, and other ways of abusing the chemical, with particular attention to redundancy and critical controls. 

The quality of the development effort would be enhanced if the routine scientific activity looked at the worst-case situation. First, the process characteristics would be better understood. Second, the specification limits for the in-process tests would be based on hard data. Third, it would be easier to evaluate... 

It is important that equipment qualifications simulate actual production conditions, including those that are worst-case situations. Tests and challenges should be repeated a sufficient number of times to assure reliable and meaningful results. All acceptance criteria must be met during the test or challenge. If any test or challenge shows that the equipment does not perform within its specifications, an evaluation should be performed to identify the cause of the failure. Corrections should be made and additional test runs performed, as needed, to verify that the equipment performs within specifications. 

Electrochemical methods have been used for determinations of species of elements in natural waters. Of the many electrochemical techniques, only a few have proved to be useful for studies of speciation in complex samples, and to possess the sensitivity required for environmental applications. The greatest concern is the measurement of the toxic fraction of a metal in an aqueous sample. The definition of a toxic fraction of a metal is that fraction of the total dissolved metal concentration that is recognised as toxic by an aquatic organism. Toxicity is measured by means of bioassays. Elowever, a universally applicable bioassay procedure cannot be adopted because the responses of different aquatic species to metal species vary. Nevertheless, bioassays should be used as means of evaluation and validation of speciation methods. A condition is that the test species (of the bioassay) should be very sensitive to the metals being studied so as to simulate a worst case situation (Florence, 1992). 

PROBLEM L2.8 Assuming the worst-case situation, a metallic sphere for which a = 4jra3, and using the center-to-center distance z between spheres as a measure of number density, N is one sphere per cubic volume z3, show that the inequality condition Na<3 becomes 4 ra3 < 3z3. 

Here, polytomy (star phytogeny) for four taxa is taken as 5 worst-case situation. Thus, probability that a phylogenetically informative site supports a tree is same for all three resolutions of polytomy, 1/3... 

Similar to approach just described, except that a clock is not 6 assumed. Method is based on a worst-case situation whereby support for correct tree is 1/3 and 2/3 for the two incorrect topologies combined... 

Another approach for testing parsimony results has been to compare the support for the best tree against that expected for a worst-case situation. If no molecular clock is assumed, then the worst-case scenario for four taxa occurs when two unrelated lineages evolve randomly and rapidly, coupled... 

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