Verdict functions in testing with a fault domain or test hypotheses

In state based testing it is common to include verdicts within test cases, the result of the test case being the verdict reached by the test run. In addition, approaches that reason about test effectiveness or produce tests that are guaranteed to find certain classes of faults are often based on either a fault domain or a set of test hypotheses. This paper considers how the presence of a fault domain or test hypotheses affects our notion of a test verdict. The analysis reveals the need for new verdicts that provide more information than the current verdicts and for verdict functions that return a verdict based on a set of test runs rather than a single test run. The concepts are illustrated in the contexts of testing from a non-deterministic finite state machine and the testing of a datatype specified using an algebraic specification language but are potentially relevant whenever fault domains or test hypotheses are used

Quantifying the reliability of fault classifiers

International audienceFault diagnostics problems can be formulated as classification tasks. Due to limited data and to uncertainty, classification algorithms are not perfectly accurate in practical applications. Maintenance decisions based on erroneous fault classifications result in inefficient resource allocations and/or operational disturbances. Thus, knowing the accuracy of classifiers is important to give confidence in the maintenance decisions. The average accuracy of a classifier on a test set of data patterns is often used as a measure of confidence in the performance of a specific classifier. However, the performance of a classifier can vary in different regions of the input data space. Several techniques have been proposed to quantify the reliability of a classifier at the level of individual classifications. Many of the proposed techniques are only applicable to specific classifiers, such as ensemble techniques and support vector machines. In this paper, we propose a meta approach based on the typicalness framework (Kolmogorov's concept of randomness), which is independent of the applied classifier. We apply the approach to a case of fault diagnosis in railway turnout systems and compare the results obtained with both extreme learning machines and echo state networks

Using formal methods to support testing

Formal methods and testing are two important approaches that assist in the development of high quality software. While traditionally these approaches have been seen as rivals, in recent years a new consensus has developed in which they are seen as complementary. This article reviews the state of the art regarding ways in which the presence of a formal specification can be used to assist testing

Automatic Alarm Correlation for Fault Identification *

Abstract In communication networks, a large number of alarms exist to signal any abnormal behavior of the network. As network faults typically result in a number of alarms, correlating these different alarms and identifying their source is a major problem in fault management. The alarm correlation problem is of major practical significance. Alarms that have not been correlated may not only lead to significant misdirected efforts, based on insufficient information, but may cause multiple COTrective actions (possibly contradictory) as each alert is handled independently. This paper proposes a general framework to solve the alarm correlation problem. We introduce a new model for faults and alarms based on probabilistic finite state machines. We propose two algorithms. The first one acquires the fault models starting from possibly incomplete and incorrect data. The second one correlates alarms in the presence of multiple faults and noisy information. Both algorithms have polynomial time complexity, use an extension of the Viterbi algorithm to deal with the corrupted data, and can be implemented in hardware. As an example, they are applied to analyze faults using data generated by the ANS (Advanced Network and Services, Inc.)/NSF T 3 network

Fault tolerant architectures for integrated aircraft electronics systems, task 2

The architectural basis for an advanced fault tolerant on-board computer to succeed the current generation of fault tolerant computers is examined. The network error tolerant system architecture is studied with particular attention to intercluster configurations and communication protocols, and to refined reliability estimates. The diagnosis of faults, so that appropriate choices for reconfiguration can be made is discussed. The analysis relates particularly to the recognition of transient faults in a system with tasks at many levels of priority. The demand driven data-flow architecture, which appears to have possible application in fault tolerant systems is described and work investigating the feasibility of automatic generation of aircraft flight control programs from abstract specifications is reported

Improving fault coverage and minimising the cost of fault identification when testing from finite state machines

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Software needs to be adequately tested in order to increase the confidence that the system being developed is reliable. However, testing is a complicated and expensive process. Formal specification based models such as finite state machines have been widely used in system modelling and testing. In this PhD thesis, we primarily investigate fault detection and identification when testing from finite state machines. The research in this thesis is mainly comprised of three topics - construction of multiple Unique Input/Output (UIO) sequences using Metaheuristic Optimisation Techniques (MOTs), the improved fault coverage by using robust Unique Input/Output Circuit (UIOC) sequences, and fault diagnosis when testing from finite state machines. In the studies of the construction of UIOs, a model is proposed where a fitness function is defined to guide the search for input sequences that are potentially UIOs. In the studies of the improved fault coverage, a new type of UIOCs is defined. Based upon the Rural Chinese Postman Algorithm (RCPA), a new approach is proposed for the construction of more robust test sequences. In the studies of fault diagnosis, heuristics are defined that attempt to lead to failures being observed in some shorter test sequences, which helps to reduce the cost of fault isolation and identification. The proposed approaches and techniques were evaluated with regard to a set of case studies, which provides experimental evidence for their efficacy.Brunel Research Initiative and Enterprise Fund (BRIEF) Award from Brunel University and Departmental bursary from Department of Information Systems and Computing, Brunel Universit

Probing context-dependent errors in quantum processors

Gates in error-prone quantum information processors are often modeled using sets of one- and two-qubit process matrices, the standard model of quantum errors. However, the results of quantum circuits on real processors often depend on additional external "context" variables. Such contexts may include the state of a spectator qubit, the time of data collection, or the temperature of control electronics. In this article we demonstrate a suite of simple, widely applicable, and statistically rigorous methods for detecting context dependence in quantum circuit experiments. They can be used on any data that comprise two or more "pools" of measurement results obtained by repeating the same set of quantum circuits in different contexts. These tools may be integrated seamlessly into standard quantum device characterization techniques, like randomized benchmarking or tomography. We experimentally demonstrate these methods by detecting and quantifying crosstalk and drift on the publicly accessible 16-qubit ibmqx3.Comment: 11 pages, 3 figures, code and data available in source file

Measurements, Models, Systems and Design

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Coding approaches to fault tolerance in dynamic systems

Also issued as Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 189-196).Sponsored through a contract with Sanders, A Lockheed Martin Company.Christoforos N. Hadjicostis