Problems with specific parameters

The fuzzy finite element method (FFEM) has become a most valuable tool for the analysis of structural dynamics problems with imprecise parameters. The present paper gives an overview of the status of development of the FFEM. The paper focuses specifically on the capabilities of the method, especially in early stages of design analysis. The formulation of design criteria in the presence of parameter uncertainties is reviewed and options for early design optimisation are discussed. 

Plant designers are well supplied with corrosion data by materials manufacturers. These data are based on both experience and laboratory studies, but the information is usually based on specific parameters such as concentration of chemical or temperature. Edeleanu has emphasised this problem... 

The basic concept behind HAZOP studies is that processes work well when operating under design conditions. When deviations from the process design conditions occur, operability problems and accidents can occur. The HAZOP study method uses guide words to assist the analysis team in considering the causes and consequences of deviations. These guide words are applied at specific points or sections in a process and are combined with specific process parameters to identify potential deviations from intended operation. 

As discussed above, hysteresis loops can appear in sorption isotherms as result of different adsorption and desorption mechanisms arising in single pores. A porous material is usually built up of interconnected pores of irregular size and geometry. Even if the adsorption mechanism is reversible, hysteresis can still occur because of network effects which are now widely accepted as being a percolation problem [21, 81] associated with specific pore connectivities. Percolation theory for the description of connectivity-related phenomena was first introduced by Broad-bent et al. [88]. Following this approach, Seaton [89] has proposed a method for the determination of connectivity parameters from nitrogen sorption measurements. 

More recent measurements have shown (61)(62) that the problem with the experiment was that the thermal effect at Tc is actually very small. In fact, after the true heat had been determined, research was (and still is) directed toward finding out why the Tc is so high (63). The Sommerfeld parameter or electronic specific heat parameter appears to be identical (1.5mJ/mol K2) in BaPbj B Og... 

The utilities check is used to verify that the utility supplied fulfills the chamber requirements as specified by the manufacturer. During IQ, the as found parameters are verified against the as specified parameters on the checklist. If the as found results are significantly different from the as specified parameters, it will be necessary to determine the cause of this discrepancy and to implement corrective actions. The utilities check is a part of the site preparation for the installation of the chamber and should include verification of the power supply, such as the voltage, amperage, and wire size and the quality, pressure, and flow rate of the feed water supply. The quality of the feed water supply is a critical component of proper operation of the chamber. Experience has shown that if the quality of the feed water does not meet the manufacturer s specifications, this will lead to premature corrosion within the humidification and/or dehumidification system and subsequent problems with maintaining the humidity in the chamber within the specified limits. 

Another way of parameterizing the problem of the progenitor structure of SN 1987A is to specify the luminosity, the total mass, and the core mass, and then to examine the behavior of the core radius, Rhb. as a function of Teff (or R). Figure 2 shows the result for models with the standard envelope composition, M = 15 M and MHe = 4 M . For fixed L, M, Mne. and RHe. if there is a solution with large Teff then there are, in fact, three solutions to the stellar structure equations, with different values of Te and R. A similar pattern exists for models with cores of 6 M . The result is not particularly sensitive to the specific parameters assumed. 

Several of the key issues are reflected in the debate over the appropriate use of pe to describe redox conditions in natural waters (129-131). The parameter is defined in terms of the activity of solvated electrons in solution (i.e., pe = - log e ), but the species e aq does not exist under environmental conditions to any significant degree. The related concept of pe (132), referring to the activity of electrons in the electrode material, may have a more realistic physical basis with respect to electrode potentials, but it does not provide an improved basis for describing redox transformations in solution. The fundamental problem is that the mechanisms of oxidation and reduction under environmental conditions do not involve electron transfer from solution (or from electrode materials, except in a few remediation applications). Instead, these mechanisms involve reactions with specific oxidant or reductant molecules, and it is these species that define the half-reactions on which estimates of environmental redox reactions should be based. 

---