Fault framework

Manual Approach for Fault Framework Modelling One approach, a manual technique, is a possibility [64] where the intersections and the fault surfaces are built together, interactively in a 3D visuahsation environment, with visual cues provided by seismic data, interpolated horizons or both. In such an approach lines are digitized onto the observed intersections. Further lines are digitized that manually construct a ruled surface. These smfaces can be interpolated using bilinear patches or sphnes. Thus in this approach the fault-fault intersections are input to the modelhng, provided by the user. A schematic is provided in Figure 9. 

Automatic Approach for Fault Framework Modelling The second approach is to interpolate the fault data for each fault separately and then to compute the fault-fault intersections. This may require some manual assistance to the algorithms to help extend surfaces so that the surfaces do intersect if there is insufficient data. In principle, surface-surface intersections are easy to compute. In practice, however, the intersections may have a very complicated topology largely arising from artefacts of the interpolation. The intersection calculations can be very delicate. At best a great deal of computer time is needed, and in the end a lot of user interaction may be required to clean up the results. Ironically it appears that in practice such an automatic approach is only suited to models with a small number of faults. The most practical... 

Fault Block Splitting (FBS) One approach to the structural modelling problem imbeds the fault surfaces into an extended set of surfaces that divide the volume of interest (VOI) into a set of closed compartments. When there are only a few faults this is a simple extension of the fault framework modelling activity. Some extra surfaces need to be added, and parts of the fault surfaces on which there is a throw, and the parts on which there is not must be specified. There is however an extra burden on the user of the software the order of the faults has to be chosen. The reason is that a convenient approach (for the software implementation) to fault block splitting is to build a binary FBS tree. Thus the volume of interest is defined, the first fault is extended so that it divides the VOI into two pieces. This operation is then repeated with each fault in turn. The extended faults must cut one or more fault blocks -the compartments in the binary FBS tree - into two pieces. In principle this is simple but in practice very difficult. 

Policy makers, practitioners, and scholars from a variety of disciplines have recently embraced a new approach to risk reduction in health care—a "systems approach"—without proposing any specific reforms of medical liability law. The Institute of Medicine (IOM) placed its imprimatur on this approach in its recent reports (Kohn et al., 2000 IOM, 2001). In its simplest form, a systems approach to risk reduction in health care posits that an injury to a patient is often the manifestation of a latent error in the system of providing care. In other words, a medical mishap is the proverbial "accident waiting to happen" because the injury-preventing tools currently deployed, including medical liability law, are aimed at finding the individuals at fault rather than the systemic causes of error. Coexistence of a systems approach to error reduction and medical liability law as a conceptual framework for policy makers implies that the latter is likely to evolve in an incremental fashion as the former makes more visible different aspects of the medical error problem. 

System diagnosis frequently lies on a model that represents the normal behavior of a particular process to be supervised. The fundamental problem comes then from the inaccuracies associated with the model, either related to the ignorance of the kinetics or its parameters, or related to the ignorance of its inputs. Within the framework of this chapter, the interest is focused on the detection and location of sensor faults in the presence of unknown inputs. Among the existing solutions based on observers, one can distinguish the approaches based on non-linear unknown inputs observers (see for example, [21],... 

As it is shown in the following, among all the uncertain reasoning methods, the Dempster-Shafer theory offers a theoretical framework particularly suited to tackle the objectives of the state manager (modularity, uncertainty management, robustness). In addition, its application is independent of the method used to determine the fault signals. 

Because it offers a framework to manage uncertain and conflicting information, the Evidence theory can be relevant to combine and to cross check fault signals. In the context of fault diagnosis, the frame of discernment 17 will be the set of all possible states of the system, i.e. all the faults that can occur on the supervised process. In other terms, we have ... 

The value applied to each mass is derived from the value of the associated residual. In a boolean framework, a threshold would be defined such that some values are declared as fault-free i.e., when the residual is lower than the threshold) and other ones as faulty i.e., when the residual is higher than the threshold). This method produces for each situation a vector of 0 and 1 that can be compared to the known signatures to isolate the fault. As already pointed out one main drawback is that if the value of the residual oscillates around the threshold, the state associated to the residual oscillates too. On the contrary, in the Evidence theory framework, an infinity of values are possible for each focal element. It is then possible to use smooth functions to produce a bba from the residual. For example, the following function has been proposed in [23] ... 

These two simple examples highlight how an uncertainty managing framework like Evidence theory can improve fault isolation performances. 

Method A involves a deductive search for all credible ways an occurrence could arise using timeline construction and a simplified fault tree approach. It can be viewed as an integrated method for systematically searching for all underlying root causes. The structured framework helps the investigator to keep on track, reach sufficient depth, and not stop prematurely at the symptoms or apparent causes. 

Figure 9-1, the two flowcharts describing root cause determinations using Methods A and B, presents general frameworks for root cause determination. Method A focuses on the logic tree method using a simplified fault tree approach. Method B focuses on the predefined tree method. 

The adsorption microcalorimetry has been also used to measure the heats of adsorption of ammonia and pyridine at 150°C on zeolites with variable offretite-erionite character [241]. The offretite sample (Si/Al = 3.9) exhibited only one population of sites with adsorption heats of NH3 near 155 kJ/mol. The presence of erionite domains in the crystals provoked the appearance of different acid site strengths and densities, as well as the presence of very strong acid sites attributed to the presence of extra-framework Al. In contrast, when the same adsorption experiments were repeated using pyridine, only crystals free from stacking faults, such as H-offretite, adsorbed this probe molecule. The presence of erionite domains in offretite drastically reduced pyridine adsorption. In crystals with erionite character, pyridine uptake could not be measured. Thus, it appears that chemisorption experiments with pyridine could serve as a diagnostic tool to quickly prove the existence of stacking faults in offretite-type crystals [241]. 

Zeolitic materials have been prominent amongst those so far studied by high resolution powder diffraction using synchrotron X-rays [36]. High definition synchrotron PXD data has been helpful in a number of framework structure determinations and has facilitated studies of planar faulting (see below). Successful Rietveld refinements of the framework structures of zeolite ZSM-11 [37, 38] and silica-ZSM-12 [39], and of the complete structures of zeolite Y containing cadmium sulfide [40] and cadmium selenide [41] clusters have been described. 

In fact, HYPOl s fault was not surprising if one relates its framework (HYPOl was composed by one ad hoc defined aromatic-nitrogen-with-lone-pair vectorial feature to simulate the coordination interaction of azole inhibitors with the iron atom of the enzyme protoporphyrin system an three aromatic rings [34]) to the chemical structure and antifungal activity of the new compounds. The activity values of these molecules, in fact, were revealed to be strongly dependent on the presence of a hydrophobic substituent (possibly aliphatic) on... 

In this chapter, an FD framework for batch chemical processes is developed, where diagnosis of sensor, actuator, and process faults can be achieved via an integrated approach. The proposed approach is based on physical redundancy for detection of sensor faults [38], while an analytical redundancy method, based on a bank of diagnostic observers, is adopted to perform process/actuator fault detection, isolation, and identification [4],... 

Progress has been made on the control structure problem. Despite its flaws, optimal control is now used in industry, though in a somewhat modified form and couched in terms of model predictive control. This new framework is much more intuitive. With this framework, fault tolerance can be... 

When considering the results obtained in the present investigation, it seems quite difficult to account for the occurrence of stacking faults in the framework of pentasils simply by the different molecular size of the tetralkylammonium cations trapped within the pores. In fact, the phenomenon occurs in the presence of tetrabutylammonium or tetramethylammonium cations which have the largest and the smallest molecular size, respectively, among the organic bases investigated. It is possible that crystallization kinetics or hydrophilicity of the quaternary ammonium cations play some role. In any case, additional experiments are needed to provide a reasonable explanation. 

Figure 5. Variation of the fault probability parameter, p, in the framework of H-BOR-E, as a function of the molar fraction of R N cations, x (see Table I), in the precursors, for the different R N /R N systems.

Figure 5. An example of disordered stacking faults. The diffraction lines denoted by ( ) are forbidden by the offretite framework, allowed for erionite, and also allowed for ZSM-34 due to stacking faults between offretite layers.

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