Catastrophic problems

The advantages of LIA over the classical (TP and TI) free energy simulation methods are (i) the absolute binding free energies are computed (AF instead of AAF), (ii) the intermediate hybrid states are eliminated and only the end-points are sampled, and (iii) a physical path is used between the initial and the final states which prevents the X goes to end-points catastrophe problem. However, a certain degree of empiricism is associated with the model, and in fact, somewhat different values for the scaling parameters a and P have been derived by various authors [274-276]. 

If sludge is not properly dispersed, the flow of oil through the engine system will be diminished, which could cause a catastrophic problem. Sludge and varnish formation processes are shown in Figure 13.2. 

An undesirable side-effect of an expansion that includes just a quadratic and a cubic term (as is employed in MM2) is that, far from the reference value, the cubic fimction passes through a maximum. This can lead to a catastrophic lengthening of bonds (Figure 4.6). One way to nci iimmodate this problem is to use the cubic contribution only when the structure is ,utficiently close to its equilibrium geometry and is well inside the true potential well. MM3 also includes a quartic term this eliminates the inversion problem and leads to an t". . 11 better description of the Morse curve. 

Phosphoric acid [7664-38-2] is rarely used because of cost and disposal problems. Nitric acid [7697-37-2] is to be avoided because it is known to cause catastrophic damage to resin, equipment, and personnel if appropriate controls and monitoring systems are not installed. 

Design. Design deficiencies can result in almost any combination of the problems described above. It can also result in catastrophic and significant spills. The best prevention is to use estabUshed codes, such as those provided by the API. 

The total heat released is the sum of the entropy contribution plus the irreversible contribution. This heat is released inside the battery at the reaction site. Heat release is not a problem for low rate appHcations however, high rate batteries must make provisions for heat dissipation. Failure to accommodate heat can lead to thermal mnaway and other catastrophic situations. 

Liquid-Metal Corrosion Liquid metals can also cause corrosion failures. The most damaging are liqmd metals which penetrate the metal along grain boundaries to cause catastrophic failure. Examples include mercury attack on aluminum alloys and attack of stainless steels by molten zinc or aluminum. A fairly common problem occurs when galvanized-structural-steel attachments are welded to stainless piping or eqmpment. In such cases it is mandatoty to remove the galvanizing completely from the area which will be heated above 260°C (500°F). 

An underlying nwtivation triggers one or more concerns about a company s facility or activity. Sometimes the underlying motivation is simply a perception that a problem exists. A single, memorable catastrophe can also galvanize concern. The motivation of an increasing number of companies to use QRA is a proactive desire to improve safety. 

But they all oxidise very rapidly indeed (see Table 21.2), and are utterly useless without coatings. The problem with coated refractory metals is, that if a break occurs in the coating (e.g. by thermal fatigue, or erosion by dust particles, etc.), catastrophic oxidation of the underlying metal will take place, leading to rapid failure. The unsafeness of this situation is a major problem that has to be solved before we can use these on-other-counts potentially excellent materials. 

The previous problems are some of the more common types encountered on a gas turbine train. Regular and preventive maintenance is the key to a successful operation. Problems will arise, but by proper monitoring of the aerothermal and mechanical problems, preventive maintenance can often avert major or catastrophic failures. 

Manganese, copper, iron, cobalt and nickel ions can all initiate oxidation. Untinned copper wire can have a catastrophic effect on natural rubber compounds with which it comes into contact. Inert fillers for use in rubbers are usually tested for traces of such metal ions, particularly copper and manganese. The problem is perhaps less serious in saturated hydrocarbon polymers but still exists. 

If a plant had periodic inspections, the impeller corrosion in No. 5 might be detected before it became a significant problem, thereby altering the failure mode from catastrophic to a degraded or an incipient failure. In a plant with routine maintenance, it is possible that Nos. 1 and 5 may be eliminated completely by routine seal and impeller changes. 

This is a difficult parameter to measure, particularly on one or two evaluation column sets. It was found that most column problems are actually caused by catastrophic instrument failure or poor filtering of the solvent or sample. 

This would affect every business that was linked to a computer juid the commotion and hysteria tliat surrounded the Y2K bug were due to the present age s dependence on computers. For c.xamplc, it was feared that the go eminent s computer system would print social security checks with amounts seen in the year 1900 and that banks would calculate dividends based on interest rates from the year 1900. The problems could have been catastrophic. Fortunately, tlie response to the "potential Y2K disaster was effective in that most corrections or patches were made before the year 2000. However, these corrections were costly and required large amounts of money to be spent." ... 

Most hydraulic systems use a positive displacement pump to generate energy within the system. Unless the pressure is controlled, these pumps will generate excessive pressure that can cause catastrophic failure of system component. A relief valve is always installed downstream of the hydraulic pump to prevent excessive pressure and to provide a positive relief should a problem develop within the system. The relief valve is designed to open at a preset system pressure. When the valve opens, it diverts flow to the receiver tank or reservoir. 

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