Return period

Payback Period Another traditional method of measuring profitability is the payback period or fixed-capital-return period. Actually, this is really a measure not of profitability but of the time it takes for cash flows to recoup the original fixed-capital expenditure. 

Rainfall Aimual 39.6 inches. The design rainfall rates for a 5 year return period are the following Time of Concentration = 15min. Intensity = 4.0 Vhr Time of Concentration = 1 hour Intensity = 2.0"/hr... 

Factor S3 is based on statistical concepts and can be varied from 1.0 to account for structures whose probable lives are shorter (or longer) than is reasonable for the application of a 50-year return-period wind. 

The rainwater runoff from buildings depends on the geographical location and storm-return period specified. Rainwater runoff from a roof is relatively clean and can discharge directly to a watercourse, lake, etc. without passing through an interceptor. 

The surface water runoff from paved/hard standing areas also depends on rainfall intensity calculated from the geographical locations of the site and storm-return period. However, the return period for a site will be far higher than for a building in order to ensure prevention of persistent flooding of the site. In many instances the local authority may specify the storm-return period as the design criterion. 

These scales of extent define the manner in which the ideas of extreme events are applicable to agriculture and forestry. Wind-throw is a small-scale process and the forest manager must grow and manage plantation forests which will survive extreme wind speeds at the spatial scale of his plantation. The question is, how rare must this extreme event be, before it may be discounted. The answer is likely to be dominated by economics and also the longevity of the plants with a 50 year harvesting interval, it seems clear that the return periods of extreme events up to 50 years (at least) are crucial. 

Fig. 5 Flood reduction in the Ebro basin in relation to the degree of impoundment (IR). Flood reduction is expressed by <5 as the ratio between the post and the pre-dam flood of a given return period Q, for this particular case the 10-year flood has been selected. See [11] for more examples...

Throughout, we have tried to identify where flexibility in a standard may legitimately be introduced. There are many different types of standard, and they all have a place in controlling chemical exposure in the environment. However, the type of standard to be used, and any measures to assess compliance with it, must be decided at an early stage. This is a policy decision. As well as the type of standard, flexibility can be introduced in the magnitude of the standard itself (it may be more or less protective) and, for standards that are subject to formal compliance assessment, in the way we decide whether the standard has been passed or failed. There is clearly more to a standard than merely the concentration, dose, or load of a substance. Aspects such as design risk, return period, and confidence of failure are integral features of the standard and, as such, should be subject to the same scrutiny. 

An important conclusion follows from the time monotonic manner (2.31) of changes in values P and d S/dt. In case the system exists near thermody namic equilibrium, the system s spontaneous evolution cannot generate any periodical auto oscillating processes. In fact, periodical processes are described along the closed evolution trajectories, which would make some thermo dynamic parameters (concentration, temperature, etc.) and, as a result, values Ji and Xj return periodically to the same values. This is inconsistent with the one directional time monotonic changes in the P value and with the con stancy of the latter in the stationary point. In terms of Lyapunov s theory of stability, the stationary state under discussion corresponds to a particular point of stable node type (see Section 3.5.2). 

The reason for the name population quantum beats is that the signal intensity (fluorescence, REMPI), integrated over all solid angles and polarization states, oscillates in time after the preparation pulse. It appears as if the population prepared in the excited state at t = 0 vanishes and returns periodically (see Fig. 9.5) (Felker and Zewail, 1984). In fact, the population does not oscillate, but the radiative capability of the time-evolving state prepared at t = 0, k(t), does oscillate. 

The number of observations (waiting time or return period ) between exceedances of a given concentration level... 

The number of exceedances (episodes) Nx(m) of a given concentration level x in a set of m successive observations c(tt) is itself a random function. Similarly, the number of averaging periods (or observations) between exceedances of the concentration level x, another random function called the waiting time, passage time, or return period, is of principal interest in the study of pollution episodes. 

The expected return period is defined as the average number of averaging periods (or observations) between exceedances of a given level x. The probability that the concentration will exceed jc for the first time at observation n is... 

On November 1, 1965 there was a severe westerly wind which was subsequently estimated to correspond to a return period of about 5 years. Tower IB collapsed at 10.30 a.m., 1A at 10.40 a.m. and 2A at 11.20 a.m. The remaining towers, particularly 2B, were extensively cracked. In February 1966, three horizontal cracks approximately 100 ft. long were found just above the ring beam of 3A and in May vertical cracks from ring beam to throat were found in 3B (Fig. 8.10). 

The flg multiplication factor applied to the spectral form is defined as a function of the return period and of the seismicity level S foreseen by the current seismic classification of the national territory. The values to be used are listed in Table 15-4. 

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