Sensitivity of the Results

Press reports and public policy discussions tend to focus on the delivered price of hydrogen compared to gasoline. But since hydrogen fuel is not a substitute for gasoline in existing ICE vehicles, this may be a poor comparison. What s usually overlooked is that the fuel cost is a 

In 2004 the Federal tax on gasoUve is 18.4 cents/gallon, and the weighted average state tax is 19.25 cents/gallon (FHA 2004). 

Ahlbrandt, T. S., R. Charpentier, T. R. Klett, et al. (2000). United States Geological Survey World Petroleum Assessment 2000 - Description and Results. United States Geological Survey. 

(1998). Costs of Storing and Transporting Hydrogen. National Renewable Energy Laboratory. 

Williams, R. E. Katofsky, and C. A. Hendriks (1997). Hydrogen Production from Natural Gas, Sequestration of Recovered CO2 in Depleted Gas Wells and Enhanced Natural Gas Recovery. Energy, 22 (2), 161-168. 

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The parametric method is an established statistical technique used for combining variables containing uncertainties, and has been advocated for use within the oil and gas industry as an alternative to Monte Carlo simulation. The main advantages of the method are its simplicity and its ability to identify the sensitivity of the result to the input variables. This allows a ranking of the variables in terms of their impact on the uncertainty of the result, and hence indicates where effort should be directed to better understand or manage the key variables in order to intervene to mitigate downside and/or take advantage of upside in the outcome. 

Check the answers and examine the sensitivity of the result to changes in the coefficients in the problem and the assumptions. 

There are a variety of ways to express absolute QRA results. Absolute frequency results are estimates of the statistical likelihood of an accident occurring. Table 3 contains examples of typical statements of absolute frequency estimates. These estimates for complex system failures are usually synthesized using basic equipment failure and operator error data. Depending upon the availability, specificity, and quality of failure data, the estimates may have considerable statistical uncertainty (e.g., factors of 10 or more because of uncertainties in the input data alone). When reporting single-point estimates or best estimates of the expected frequency of rare events (i.e., events not expected to occur within the operating life of a plant), analysts sometimes provide a measure of the sensitivity of the results arising from data uncertainties. 

In any case, like frequency analysis, examining the uncertainties and sensitivities of the results to changes in boundary conditions and assumptions provides greater perspective. The level of effort required for a consequence analysis will be a function of the number of different accident scenarios being analyzed the number of effects the accident sequence produces and the detail with which the release, dispersion, and effects on the targets of interest is estimated. The cost of the consequence analysis can typically be 25% to 50% of the total cost of a large QRA. 

When a risk or reliability analysis has been performed, it is appropriate to inquire into the sensitivity of the results to uncertainties in data. One type of sensitivity analysis is the effect on system reliability that results from a small change in a component s failure probability. A problem in doing this is determining the amount of data uncertainty that is reasonable. The amount of change... 

One way to proceed with this example is to estimate the error structure. Then using two different estimates, the sensitivity of the results to the assumed error structure can be examined. The first estimate of the covariance matrix used here is... 

We might also note here, almost parenthetically, that if the hypothesis test gives a statistically significant result, it would be valid to calculate the sensitivity of the result to the difference between the two groups (i.e., divide the difference in the means of the two groups by the difference in the values of the variable that correspond to the experimental and control groups). 

These equations can be solved in a least-squares sense, but in general they do not have a unique solution. The finite phase space width of the basis functions tends to dampen the sensitivity of the results, especially branching ratios, to the particular solution that is chosen. This sensitivity is further reduced when convergence with respect to multispawn is demonstrated. 

In this chapter I explained how isotope ratios may be calculated from equations that are closely related, but not identical, to the equations for the bulk species. Extra terms arise in the isotope equations because isotopic composition is most conveniently expressed in terms of ratios of concentrations. I illustrated the use of these equations in a calculation of the carbon isotopic composition of atmosphere, surface ocean, and deep ocean and in the response of isotope ratios to the combustion of fossil fuels. As an alternative application, I simulated the response of the carbon system in an evaporating lagoon to seasonal changes in biological productivity, temperature, and evaporation rate. With a simulation like the one presented here it is quite easy to explore the effects of various perturbations. Although not done here, it would be easy also to examine the sensitivity of the results to such parameters as water depth and salinity. 

Using the HAZARD I software to calculate the outcome of each of those fires, checking the sensitivity of the results to any assumptions made and... 

Nitroglycol (NGC) has similar physical and chemical properties to those of NG. However, its vapor pressure is too high to permit its use as a major component of propellants and explosives. NGG is used as an additive to reduce the freezing temperature of NG and to formulate explosives. However, the shock-sensitivity of the resulting NG-based explosives is much higher than that of other types of explosives. 

An investigation should be made concerning the sensitivity of the results of analysis to the method of handling missing values, especially if the number of missing values is substantial. ... 

There are considerable difficulties in comparing theory and experiment even in such model experiments. The theoretical calculations are subject to the approximations inherent in the method, and also to uncertainties in the pupil function used to characterize the lens and in the two parameters used to characterize the crack. The experiments are subject to the difficulties of making a crack that is straight and flat to a fraction of the acoustic wavelength used, over the length measured by the line-focus-beam lens, and to the sensitivity of the results in some cases to small changes in x or z. Nevertheless, when all these considerations are taken into account it does seem... 

The sensitivity of the resulting electrochemical sensor was tuned via control over the number of assembled layers on the conductive surface 47 For example, layered assemblies consisting of cyclophane 3 and gold NPs were produced on ITO surfaces. The number of layers was varied from one to five in the presence of an... 

As indicated above, paraffin wax, when incorporated with expls, is known, as early as 1892, to have reduced the mechanical sensitivity of the resulting expl compn. Most work in the US in investigating waxes for the purpose of desensitizing expls did not start until the late 1930 s early 1940 s. Most of the investigative... 

Ref 28 continues work recommended by Ref 26. Results of the work indicated the Beeswax Substitute 776 and Pentawax 177 are most promising. When as little as 2% of either of these two waxes are properly applied to PETN, the sensitivity of the resulting expl to impact is approx equal to that of Tetryl. It is further reported that when the PETN-wax compns are pressed to densities above 1.43g/cc, increase in the proportion of the wax in PETN-wax compns results in an increase in the rate of detonation which may be as great as 190m/sec. 

In this study we also considered the conformational sensitivity of the results. While we usually try to find the conformation with the minimal COSMO energy by a conformational search (see chapter 11.3 for details), we tried a direct AM1/COSMO... 

Fig. 3.40(a), top]. In situation II ( AG/ = AGj > Xc) the effect is completely lost since both reaction zones have exactly the same shape [Fig. 3.40(b), top]. Thus the initial ion distribution, even when it coincides with one of them, cannot be inside the other. As a consequence, only the descending (diffusion-controlled) branch of this dependence is seen in Figure 3.40(a) (bottom). Such a high sensitivity of the results to the shape and relative location of the ionization and recombination zones makes any model simplifications of these zones undesirable. 

In the same figure we also demonstrate the sensitivity of the results to the ratio of the diffusion coefficients in the stable and excited pairs, D Q and D Q, which increases from (a) to (c). The difference in the diffusion coefficients ignored in the convolution recipe affects the field dependence no less than the contact approximation. This is the unique advantage of IET, that it is free of any limitations of this sort and can be used for quantitative investigations of field effects, at any space dispersion of quenching rate and at arbitrary diffusion coefficients. In fact, this is diffusion of the excited molecule that affects the field dependence of k0. By slowing down this diffusion, one increases the encounter time x,/ and thus enhances the field acceleration of quenching. 

Murray CW, Baxter CA, Frenkel AD (1999) The sensitivity of the results of molecular docking to induced fit effects application to thrombin, thermolysin and neuraminidase. J Comput Aided Mol Des 13(6) 547-562... 

An important assumption made in the LSCF construction is that the SLBOs are transferable within a wide class of molecules. The frozen character of the boundary SLBO causes the sensitivity of the results obtained within the LSCF scheme to the size of the QM region. The electronic structure of the QM region is described... 

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