Cumulative effects

It is usually allowed and acceptable in most cases that a minor alteration is introduced to a mechanical part. When the same or similar change is applied to the same part multiple times, or to multiple parts that are installed on the same machine, the resultant cumulative effects of this relatively minor change can accumulate and cross the critical threshold. It might be within 

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Generally speaking, intermolecular forces act over a short range. Were this not the case, the specific energy of a portion of matter would depend on its size quantities such as molar enthalpies of formation would be extensive variables On the other hand, the cumulative effects of these forces between macroscopic bodies extend over a rather long range and the discussion of such situations constitutes the chief subject of this chapter. 

When a benzene ring bears two or more substituents both its reactivity and the site of further substitution can usually be predicted from the cumulative effects of its substituents In the simplest cases all the available sites are equivalent and substitution at any one of them gives the same product... 

When designing and evaluating an analytical method, we usually make three separate considerations of experimental error. First, before beginning an analysis, errors associated with each measurement are evaluated to ensure that their cumulative effect will not limit the utility of the analysis. Errors known or believed to affect the result can then be minimized. Second, during the analysis the measurement process is monitored, ensuring that it remains under control. Finally, at the end of the analysis the quality of the measurements and the result are evaluated and compared with the original design criteria. This chapter is an introduction to the sources and evaluation of errors in analytical measurements, the effect of measurement error on the result of an analysis, and the statistical analysis of data. 

So what is the total uncertainty when using this pipet to deliver two successive volumes of solution from the previous discussion we know that the total uncertainty is greater than 0.000 mL and less than 0.012 mL. To estimate the cumulative effect of multiple uncertainties, we use a mathematical technique known as the propagation of uncertainty. Our treatment of the propagation of uncertainty is based on a few simple rules that we will not derive. A more thorough treatment can be found elsewhere. ... 

We assume that the observed interference is the cumulative effect of the contributions of the individual polymer molecules and that solute-solute interactions do not enter the picture. This effectively limits the model to dilute solutions. This restriction is not particularly troublesome, since our development of the Rayleigh theory also assumes dilute solutions. 

Cumulative Damage. Pressure vessels may be subjected to a variety of stress cycles during service some of these cycles have ampHtudes below the fatigue (endurance) limit of the material and some have ampHtudes various amounts above it. The simplest and most commonly used method for evaluating the cumulative effect of these various cycles is a linear damage relationship in which it is assumed that, if cycles would produce failure at a... 

Cumulative effects are those where there is progressive injury and worsening of the toxic effect as a result of repeated-exposure conditions. Each exposure produces a further increment of injury a dding to that already existing. Many materials known to induce a particular type of toxic effect by acute exposure can also eUcit the same effect by a cumulative procedure from repetitive exposure to a dose less than that causing threshold injury by acute exposure. 

Repeated exposure to elevated temperature has a cumulative effect. For example, at a given set of exposure conditions, the property losses ate about the same after six exposure periods of one month each and after a single 6-month period. 

Geochemical Stage. The conversion of peat to bituminous coal is the result of the cumulative effects of temperature and pressure over a long time. The sediment covering the peat provides the pressure and insulation so that the earth s internal heat can be appUed to the conversion. The temperature increase is about 4 to 8°C for each 100 m of depth. The changes in plant matter are termed normal coalification. 

Oxygen, nitrogen, and carbon promote brittle behavior in all titanium alloys, and it is important to control the cumulative effect of these three elements during casting operations. 

The closer one is to the failure, the more its direct effects are apparent. The cumulative effects of failure are often overlooked in the rush to fix the immediate problem. Too often, the cause of failure is ignored or forgotten because of time constraints or indifference. The failure or corrosion is considered just a cost of doing business. Inevitably, such problems become chronic associated costs, tribulations, and delays become ingrained. Problems persist until cost or concern overwhelm corporate inertia. A temporary solution is no longer acceptable the correct solution is to identify and eliminate the failure. Preventative costs are almost always a small fraction of those associated with neglect. 

Through the tap-offs of the bus, the unit auxiliary transformers (UATs) are connected to feed the station auxiliary services. For more clarity we have taken out the portion of the tap-offs from Figure 13.21 and redrawn it in Figure 13.18 to illustrate the above system and its interconnections. The tap-offs are now subject to the cumulative inOuence of the two supply sources. In the event of a fault on this section, both the sources would feed the same and the fault current through the tap-offs would add up. The tap-offs should thus be designed for the cumulative effect of both fault levels. For the sake of an easy reference, Table 13.8 suggests a few typical values of fault currents, worked out on the basis of data considered for the G and GT. One such example is also worked out in Example 13.3. 

Aeeurate measurement of harmonic quantities and their cumulative effect is a complex subject, and is not possible to determine theoretically with the help of algebraic equations. But it can be easily measured with the help of a harmonic analyser. Cigre (1989) has made a comprehensive study of the likely harmonics and their amplitudes that may be present in a power system. These are briefly described in Table 23.1. 

Refer to Table 23.1, which shows the average cumulative effect of all the harmonics that may be present in a power system. If we can provide a series reactor of 6% of the total kVAr of the capacitor banks connected on the system, most of the harmonics present in the. system can be suppressed. With this reactance, the system would be tuned to below the fifth harmonic (at 204 Hz) for a 50 Hz system as derived below. 

In this switching, the cumulative effect of the applied voltage and the trapped charge of the already charged capacitors is of little relevance but the resultant eurrent is extremely high as derived below. 

A three-phase system has three current-carrying conductors in close proximity. While the conductors of phases R and B will have an almost identical impedance, with the same skin and the proximity effects, the conductor of phase Kis under the cumulative effect of electric fields... 

Another way to evaluate risks is to calculate the sensitivity of the total risk estimates to changes in assumptions, frequencies, or consequences. Risk analysts tend to be conservative in their assumptions and calculations, and the cumulative effect of this conservatism may be a substantial overestimation of risk. For example, always assuming that short-term exposure to chemical concentrations above some threshold limit value will cause serious injury may severely skew the calculated risks of health effects. If you do not understand the sensitivity of the risk results to this conservative assumption, you may misallocate your loss prevention resources or misinform your company or the public about the actual risk. 

Cumulative Effect the impact on an AQRV resulting from total pollutant loading from all sources including the contributing effects of new and modified sources of air pollution. 

Hazardous waste means any waste or combination of wastes which pose a substantial present or potential hazard to human health or living organisms because such wastes are nondegradable or persistent in nature or because they can biologically magnify or because they can be lethal or because they may otherwise cause or tend to cause detrimental cumulative effects. 

Doses from several small exposures over a pjcriod of time (chronic exposure) causing no immediate effect, may also result in a delayed effect. This cumulative effect may be serious or minor. 

There are concerns that land application of sludge will result in an increase of pathogenic bacteria, viruses, parasites, chemicals and metals in drinking water reservoirs, aquifers, and the food chain. This raises additional concerns of cumulative effects of metals in cropped soils. Research shows that if metals such as zinc, copper, lead, nickel, mercury, and cadmium are allowed to build up in soils due to many applications of sludges over the years, they could be released at... 

Cumulative effect The building up of dangerous products within the body with successive or continuing exposures. 

Where you devise original solutions to the measurement of characteristics the theory and development of the method should be documented and retained as evidence of the validity of the measurement method. Any new measurement methods should be proven by rigorous experiment to detect the measurement uncertainty and cumulative effect of the errors in each measurement process. The samples used for proving the method should also be retained so as to provide a means of repeating the measurements should it prove necessary. 

Little is known about the cumulative effects of factors such as prolonged working hours and extra mural demands on workers and how such demands interact with workers performance reserves and productivity. 

In most of these instances the overall reduction in heat flowmay be small, but the cumulative effect within a system maybe enough to reduce the evaporating temperature by as much as 2 K, resulting in a loss in COP of some 6%. 

Toxicity. MEDINA is apparently non-toxic to rabbit penile mucosa its cumulative effect on abraded and intact rabbit skin is slightly greater than Tetryl no damage was observed to rabbit cornea and there was no evidence of sensitization by subcutaneous injection in guinea pigs. It was concluded that its toxicity is similar to that of Tetryl (Ref 11, p 138)... 

It can be seen that k in Eq. (10) replaces the system-describing parameters L and Ah in Eq. (1). A direct test of the hypothesis is therefore to plot (j> against k for fixed values of P, G, and d, with L and Ah varying. For the hypothesis to be correct, the data points must all lie on a smooth curve. Experience shows, however, that plotting (f> against k often produces an undue amount of scatter which may obscure and distort any true relationship existing. This enhanced scatter is caused by the cumulative effect of experimental errors in the various terms in the heat-balance equation from which the quality k is derived. 

Fhtients with liver or kidney disease are usually given dragp with caution because a cumulative effect may occur. When the patient is unable to excrete the drug at a normal rate the drug accumulates in the body, causing atoxic reaction. Sometimes, the primary health care provider lowers the dose of the drug to prevent a toxic drug reaction. 

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