Aircraft fuel rig system fault diagnostics based on the application of digraphs

The issue of fault diagnostics is a dominant factor concerning current engineering systems. Information regarding possible failures is required in order to minimize disruption caused to functionality. A method proposed in this paper utilizes digraphs to model the information flow within an application system. Digraphs are composed from a set of nodes representing system process variables or component failure modes. The nodes are connected by signed edges thus illustrating the influence, be it positive or negative, one node has on another. System fault diagnostics is conducted through a procedure of back-tracing in the digraph from a known deviating variable. A computational method has been developed to conduct this process. Comparisons are made between retrieved transmitter readings and those expected while the system is in a known operating mode. Any noted deviations are assumed to indicate the presence of a failure. The current paper looks in detail at the application of the digraph diagnostic method to an industrially based test stand of an aircraft fuel system. This research includes transient system effects; the rate of change of a parameter is taken into consideration as a means of monitoring the system dynamically. The validity of the results achieved, through performing fault diagnostics based on the use of a digraph model, is evaluated. Finally, the effectiveness and scalability issues associated with the application of the method are addressed

Enhanced diagnosis of faults using the digraph approach applied to a dynamic aircraft fuel system

Malfunctions within commercial aircraft can considerably increase both the financial cost of downtime and the disruption caused to passenger travel. For this reason prompt detection, diagnosis, and rectification of faults is imperative to the successful operation of such a system. In this paper the fault diagnostic problem is tackled based on the application of the digraph procedure. Digraphs model the information flow, and hence fault propagation, through a system. A computational method has been successfully developed to conduct the fault diagnostics process and produce a list of the fault combinations determined. The scope of the method has been demonstrated by consideration of two modes of operation to the application of a commercial aircraft fuel system, namely that of a Boeing 777. In addition the paper highlights the contribution of the development of a reduction method to enhance the likelihood of identifying the possible failure causes in three ways from different viewpoints. The three methods provide the option of determining the component at fault, the most probable failure mode cause, and also evidence for a particular component fault

Aircraft fuel system diagnostics using digraphs

Faults within any system will decrease its functionality, with the worst case scenario being complete system failure. When faults do occur it is imperative they can be diagnosed and ultimately rectified as quickly as possible, minimising the effects of such a failure. In the case of a commercial aircraft system efficient diagnosis can optimise the time to return the aircraft to service, thus allowing less disruption to passenger travel. For a military air vehicle diagnosis of the status of the system can mean that missions can be altered or aborted given the faults detected. With the increasing complexity of modern day systems, designed for reliability, it is usually several items that are required to fail before catastrophic or complete system failure is experienced, thus diagnosis of multiple faults is important. In addition, for the most effective diagnosis, detection needs to happen in real time. A method of finding faults or combinations of faults as they occur is the subject of this paper. The approach uses sensor readings to assess the state of the system. The method of digraphs is used to diagnose the faults by considering deviations in the sensor readings from the expected system state. Digraphs allow a means to represent the propagation of inputs through a system, reflecting the relationships and interactions between the components. The primary research has shown the applicability of using the digraph based approach for fault diagnosis on a simulated test stand of an aircraft fuel system. The analysis has assumed steady state conditions although guidelines have been provided for use for dynamic behaviour. The technique has shown potential for extension for diagnosis to the real aircraft fuel system

The role of social and/or ecological contexts influences assessment strategy use in Tilapia

Animals engage in costly agonistic contests during which winners procure resources. During these interactions, the combatants obtain and use information to make decisions on whether to persist or to withdraw from the fight, which is termed assessment. Recent theory and work have suggested that the types of assessment employed may be more variable than previously thought, with the use of different strategies possibly being influenced by social and ecological conditions during priming. This study addresses the contextual components (social and ecological) that affect the utilization of one assessment strategy over another. Male tilapia were primed with different combinations of social (large and small animals) and ecological (resource rich or poor) contexts 24 hr prior to fighting in staged, dyadic contests. When opponents were primed with the same context, a clear assessment strategy emerged and differed as a function of priming treatment. Conversely, when fish were primed with different treatment contexts, there was no discernible assessment. In addition, priming conditions had differing effects for large and small fish. Thus, assessment strategies in cichlids are dependent upon a combination of social, ecological contexts and size of the animal. Since assessment strategies change as a function of both of these contexts, as well as others, future framework investigating assessment strategies should include both intrinsic and extrinsic factors that may shape fighting dynamics.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151902/1/eth12936_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151902/2/eth12936.pd

Comparison of digraph and fault tree based approaches for system fault diagnostics

The issue of fault diagnosis has become ever prevalent in engineering systems. Information concerning possible failures within a system can help to minimise the disruption to the functionality of the system by allowing quick rectification. Traditional approaches to fault diagnosis within engineering systems have focused on sequential testing procedures and real time mechanisms. Both methods have been predominantly limited to single fault causes. Latest approaches also consider the issue of multiple faults in reflection to the characteristics of modern day systems designed for high reliability. The bases of these approaches are the fault tree analysis technique and the method of digraphs. Both use a comparative approach to consider differences between actual system behaviour and that expected. This paper focuses on reviewing the developments with these methods to diagnose faults within an aircraft fuel system and to compare their effectiveness and future potential

Integrated system fault diagnostics utilising digraph and fault tree-based approaches

With the growing intolerance to failures within systems, the issue of fault diagnosis has become ever prevalent. Information concerning these possible failures can help to minimise the disruption to the functionality of the system by allowing quick rectification. Traditional approaches to fault diagnosis within engineering systems have focused on sequential testing procedures and real time mechanisms. Both methods have been predominantly limited to single fault causes. Latest approaches also consider the issue of multiple faults in reflection to the characteristics of modern day systems designed for high reliability. In addition, a diagnostic capability is required in real time and for changeable system functionality. This paper focuses on two approaches which have been developed to cater for the demands of diagnosis within current engineering systems, namely application of the fault tree analysis technique and the method of digraphs. Both use a comparative approach to consider differences between actual system behaviour and that expected. The procedural guidelines are discussed for each method, with an experimental aircraft fuel system used to test and demonstrate the features of the techniques. The effectiveness of the approaches are compared and their future potential highlighted

An Analysis of Multi-Processors Using Ischium

Unified optimal models have led to many extensive advances, including rasterization and robots. After years of important research into the Turing machine, we disconfirm the emulation of interrupts, demonstrates the private importance of complexity theory. Ischium, our new heuristic for the transistor, is the solution to all of these challenges