Parametric study approach

To evaluate fission product release in a reactor, it is necessary to supply the appropriate particle geometry, diffusion coefficients, and distribution coefficients. This is a formidable task. To approach this problem, postirradiation fission product release has been studied as a function of temperature. The results of these studies are complex and require considerable interpretation. The SLIDER code without a source term has proved to be of considerable value in this interpretation. Parametric studies have been made of the integrated release of fission products, initially wholly in the fueled region, as a function of the diffusion coefficients and the distribution coefficients. These studies have led to observations of critical features in describing integrated fission product releases. From experimental values associated with these critical features, it is possible to evaluate at least partially diffusion coefficients and distribution coefficients. These experimental values may then be put back into SLIDER with appropriate birth and decay rates to evaluate inreactor particle fission product releases. Figure 11 is a representation of SLIDER simulation of a simplified postirradiation fission product release experiment. Calculations have been made with the following pertinent input data ... 

Parametric studies in spray dryer pilot plants have demonstrated that the main variable affecting S02 removal in the bag filters, besides the stoichiometric ratio of Ca(0H>2 to SO2, is the approach to the adiabatic saturation temperature of the flue gases... 

In the second phase of the parametric study the removal of halogens from the reaction products was examined. Two different halogen removal methods were studied. The first method used a calcium oxide fixed bed placed between the reactor and condenser to remove organochloride vapours. However, it was found that the calcium oxide bed would plug up very rapidly if PET was present in the feed mixture and would become ineffective. This is because the PET would depolymerize into terephthalic acid and CO2 and would react with calcium oxide and cause it to plug up. The second method that was used for removal of chlorine was to add calcium oxide or hydroxide directly into the reactor with the plastic feed. It was found that this approach is far more effective than the previous method. Through trial and error it was found that calcium hydroxide feed of 10 wt% would remove the highest amount of chlorine (Table 19.7) [9]. 

Some authors believe that the inclined line of impedance at low frequencies comes from the pore size distribution of porous materials [171,182], and a few attempts have been made to consider the effect of pore size distributions (PSD) on the impedance of a porous electrode [171,182], although the PSD must contribute considerably to the distributed characteristics [171,182]. The impedance curve in the Nyquist plot is observed to change with the shape of a pore in the intermediate frequency region, despite its similarity to a cylindrical pore at extremely low or high frequencies. Some authors have reported that the real part of the reduced impedance (the ratio of impedance of a pore to electrolyte resistance in a pore) approached one-third at low frequency, irrespective of the shape of a pore [171,182]. The PSD effect is difQcult to take into account, particularly because of the time-consuming calculations required by this method, while a parametric study is difficult because of too many parameters (sizes of different pores), but some analytical solutions are being used to represent the pore size distribution of a porous electrode [171,182]. 

One approach is to simply have no resistors anywhere over the entire surface, with the exception of a few colnmns at the edges. An example is shown in Fig. 1.5b, where the two outer colnmns have been loaded with 200 ohms, the next ones toward the center with 100 ohms, and finally the third column with 50 ohms. We observe a significant rednction of the ripple amplitudes as compared to the nnloaded case in Fig. 1.3c. It shonld be noted that no parametric study was done on the resistive values of the loads at this point. More in Chapter 4. 

Recent theoretical studies have become much more complex. New computer-assisted techniques permit the use of finite-element matrix-theory type approaches. The effects of important variables are being determined by parametric studies. More complex joints are also being studied. New adherend materials, including advanced filamentary composites, are also being evaluated. The elastic, low-deflection, constant temperature behavior of scarf and stepped-lap joints has been replaced by elastic-plastic, large-deflection behavior, combined with thermal expansion differences, or curing shrinkage-induced residual stresses. 

Clearly, to exploit the materials used fully, it is necessary to reduce the throughthickness stress, whilst allowing the in-plane and fillet stresses to increase. Any design method must be able to quantify these stresses and to determine the effect of design variables on them in an explicit manner. One approach is to conduct a systematic, parametric study to check the influence of varying different design parameters outlined below (see for example reference 5.40). 

In both models, the general approach has been to minimize the amount of detailed physics calculations required as input as long as such simplifications do not introduce appreciable error. As a result, the models as developed are ideal for doing inexpensive parametric studies, as well as being useful reactor design tools. 

The hydrodynamics of the experimental system can be described theoretically. Such approach is very important for correct interpretation of the experimental results, and for their extrapolation for the conditions not attainable in the existing experimental system. With the mathematical model the parametric study of the system is also possible, what can reveal the most important factors responsible for the occurrence of the specific transport phenomena. The model was presented in details elsewhere [2]. It was based on the equations of the momentum and mass transfer in the simplified two-dimensional geometry of the air-water-surfactant system. Those basic equations were supplemented with the equation of state for the phopsholipid monolayer. The resultant set of equations with the appropriate initial and boundary conditions was solved numerically and led to temporal profiles of the surface density of the surfactant, T [mol m ], surface tension, a [N m ], and velocity of the interface. Vs [m s ]. The surface tension variation and velocity field obtained from the computations can be compared with the results of experiments conducted with the LFB. 

Carbon monoxide is the most understood poisoning phenomena due to extensive studies. The goal of this chapter (7) is to provide a full understanding of the CO poisoning phenomenon, sufficient to enable the reader to numerically simulate CO poisoning as well as its mitigation methods. Empirical models are usually developed and an example of fhis is described. Mathematical models, which include the fundamental physical and chemical properties of the system under study, are more useful for parametric studies, such as, for example, the effects of fhe catalyst layer structure. Several approaches to the mathematical models are briefly described. 

Any attempts to mimic such natural structural arrangements using ceramic materials needs further understanding of how the geometrical ratios and material properties may contribute/control the crack path selection process in such structures. One could approach such evaluations through a full parametric study of the problem. However, given the number of interations and numerical efforts involved, a response-surface-methodology-based approach is more practical [18]. 

Therefore, functional relations describing q in terms of period and ductility should satisfy these requirements. Such statistical estimations of q have shown that the latter limit is actually approached asymptotically from above (Nassar and KraWinkler 1991) however, the constraint imposed by the first limit has been relaxed in certain statistical studies in order to obtain better statistical correlations of qn—fi—T in the short period (Riddell 1995). A brief description of several such functional relations and the corresponding parametric studies involved are given herein a graphical comparistm of the different q/j-fi—T spectral models for target ductilities jii = 4 and 6 is given in Fig. 4, as proposed by these studies. 

The validity of this approach - often called superposition theorem - is shown by Kausel and Roesset (1974). The main advantage of the method is that each step can be handled independently and with different algorithms. Further, it allows an insight into the contributions from each analysis step and is particularly suitable for parametric studies. 

In this approach, a hydrodynamic analysis of a soft contact lens during the sliding motion as well as during a shock is presented. The model developed allows a parametric study of the contact in order to give an adequate soft lens movement to... 

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