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Model-based fault detection and isolation (FDI) methods are used to determine faults by examining the deviation of sensed information from anticipated system trajectories. In this paper, a comprehensive model-based FDI framework is proposed to improve fault identifiability and reduce false alarms during maintenance testing. In this framework, robust maintenance tests are designed and conducted, followed by false alarm analysis. The optimal tests designed improve the identifiability of faults by manipulating system inputs to maximize information with respect to faults, in the form of sensitivities of the system outputs. Each test design is evaluated a posteriori using the system model to explore whether false alarms are plausible, given system uncertainty and measurement noise. The proposed framework is applied on two case studies that compare the identifiability of faults at nominal and optimal system test conditions. The first case study focuses on a plate fin heat exchanger with various levels of particulate fouling at steady-state and transient conditions. The second case study deals with the same type of fault but in an aircraft environmental control system with multiple sources of uncertainty.

In the process of transformer overhaul and maintenance in nuclear power plant, a large number of Chinese technical documents have been accumulated, including transformer structure and corresponding failure mode, failure cause analysis, maintenance test record, inspection and defect elimination record, fault problem and other information. It contains rich fault information, fault cause description and troubleshooting method and other key features of fault and maintenance, which is helpful for the maintenance of transformer To guide the operation and inspection work and fault diagnosis and analysis work. In CSCW and its related fields, artificial intelligence method and knowledge engineering technology, especially konwledge graphping technology and its intelligent application, have attracted extensive attention from academia and industry. Based on a series of data acquisition, analysis and algorithm flow, we have a deep understanding of the practical effect of applying intelligent algorithm directly to the construction of transformer fault konwledge graph and decision support application.

The on-board power supply system provides power for the launch vehicle. The power transmission and transformation system plays an irreplaceable role to ensure that the on-board power supply system receives the normal working voltage of the launch vehicle. There are many types of faults in power transmission and transformation systems. The traditional faulty diagnosis method of power transmission and transformation equipment has the disadvantages of being susceptible to experts’ subjectivity and model’s ossification. In this paper, a new method of equipment fault diagnosis based on big data is proposed. On the basis of big data, this paper introduces the failure mode clustering algorithm, the state parameter correlation analysis algorithm, the fault diagnosis method based on the correlation matrix, and other key fault diagnosis technologies. The fault record data of the 400 kV voltage grade oil-immersed transformer bushing in the past ten years by a Chinese combat unit is used as a case for demonstration. The results show that the accuracy rate of SC-LSTM-K-means clustering model exceeds 95%. And the fault classification mode can be accurately obtained. A priori correlation algorithm with TA coefficient can be used to evaluate the strong and weak relationship between the state parameters; the fault diagnosis matrix based on Pearson’s correlation coefficient can accurately determine the fault mode consistent with the actual operation and maintenance test results. Therefore, the fault diagnosis method of power transmission and transformation system based on big data can both effectively obtain the inherent laws of historical data and realize more accurate fault diagnosis with data adaptability.

The PRESLEEP project is aimed at the fine assessment and validation of the proposed proprietary methodology/technology, for the automatic detection and prediction of the transition between the behavioural states of a subject (e.g. wakefulness, drowsiness and sleeping) through a wearable Cyber Physical System (CPS). The Intellectual Property (IP) is based on a combined multi-factor and multi-domain analysis thus being able to extract a robust set of parameters despite of the, generally, low quality of the physiological signals measured through a wearable system applied to the wrist of the subject. An application experiment has been carried out at AVL, based on reduced wakefulness maintenance test procedure, to validate the algorithm’s detection and prediction capability once the subject is driving in the dynamic vehicle simulator.

This paper takes the construction and operation of city ecological park as the research object, and discusses the planning and design method and process based on BIM from the perspective of tourists. According to the study of the definition, function, value and difficulties of BIM, the application of BIM in the whole construction cycle of ecological park project is summarized and analyzed, and the principles and concepts of urban ecological park planning and design are clarified. Then we mainly introduces the layout template setting, 4D construction simulation, development of operation and maintenance test data interface, and realization of collaborative work. The research results show that BIM technology can realize the visual display of project design phase, which greatly increases the amount of construction drawings, and improves the design efficiency. It also controls the project cost and shortens the construction period, to promote the overall improvement of similar project management.

IEC 61850 is the established standard for substation communication. Since the standard describes different stages of lifecycle of Substation Automation Systems the demands for specification, testing, and especially simulation differ. The approach described in this study can be used in the different stages and fulfil practical requirements. It describes the requirements for simulation and proposes an implementation applicable. If a single Intelligent Electronic Device (IED) and its data model to be simulated in technical investigation phase is sufficient at Factory Acceptance Testing and Site Acceptance Testing multiple IEDs and utilised services as GOOSE and reports will be needed. In addition, the methods described for indicating test mode/behaviour and simulation indication become important. The simulation has to be embedded in testing environment and interact with tools to be used for visualisation of changes in IED's data model. Advanced services in IEC 61850 like setting groups control, switching device control and file transfer have to be added. The requirements will be discussed from a utility's perspective. The method described can be extended for routine testing and maintenance testing, e.g. after firmware upgrades. An outlook develops a vision to be utilised for automation and control testing.

Regression testing is one of the types of maintenance testing and it is performed in case of bug-fixing or whenever there is any new functionality incorporate in the dynamic environment of software...

This paper provides a new method for designing the load of transmitters switch components on provincial radar test platform. Based on the calculation of the specific parameters related to the actual charge switch components, the load-related data model is obtained, the simulation is carried out, and the results are consistent with the actual test results. Through the theoretical numerical analysis of the load of the charging switch components of the transmitter device in the new generation of weather radar maintenance test platform, radar maintenance personnel at all levels can deepen the thorough understanding of the CINRAD/SA transmitter and have some enlightenment and improvement on the maintenance guarantee ability of the new generation of weather radar.

A method is proposed to improve system reliability in terms of self-detection and isolation of discrete faults. The application of this method on the design of built-in tests for maintenance is presented using the case of aircraft environmental control system maintenance testing. Built-in testing during aircraft on-ground maintenance allows for wider system input variability due to the absence of operational constraints and requirements. This provides an opportunity to optimally design tests that improve the fault detection and isolation capabilities for operators and maintenance crews. A general mathematical framework for built-in test design is shown using a model-based active fault detection and isolation technique. The motivation for this paper is first illustrated through a case study showing the inability to detect and isolate faults at different conditions, demonstrating how system states contribute to these issues. The success of the proposed framework is demonstrated by designing built-in tests that are capable of fully detecting and isolating a multiplicity of faults common to aircraft environmental control systems. We conclude by presenting the value of the proposed method of detecting and isolating faults, as a solution to a constrained optimization problem with the admissible system inputs as manipulated variables.

In order to reach commercially-relevant availability, future fusion power plants must minimise the duration of maintenance shutdowns. However, as radiation levels increase, so too will the number of maintenance tasks that must be performed without human access. To meet these conflicting constraints, remote maintenance systems must therefore significantly increase their capabilities, performing tasks faster and in parallel. Unfortunately, the current teleoperation-based maintenance approach is inherently limited in these regards. Automation emerges as a potential solution, having demonstrated dramatic productivity gains in manufacturing across the world. The European DEMO project has begun to explore the feasibility of automated maintenance as a route to meeting the challenging availability targets. To this end, the Automated Inspection and Maintenance Test Unit (AIM-TU) has been designed and constructed, providing a highly versatile test platform able to adapt to evolving R&D programmes. It consists of a modular robot cell equipped with two robot arms mounted on linear rails, interchangeable end-of-arm-tooling, a variety of vision sensors and a fully integrated safety system. The hardware is supported by a modular software architecture, which permits different control input modes and provides a digital twin simulation of the cell for virtual verification and validation of control algorithms. This paper provides an overview of the system’s capabilities and reports on the first automated maintenance feasibility tests performed on the cell: automatic replacement of JET reactor tiles and automatic contactless inspection of tile anomalies.

During the research there were two domain analyses performed: one of maintenance testing and the other of ontologies. The goal of the research was the increase of maintenance testing quality by developing a domain knowledge base and common scenarios which are used in the real life maintenance testing in the form of the ontology. The analysis shown, that it's possible to use ontologies to make the process of maintenance testing easier. The testing in the development process and testing in the process of software maintenance were defined and structured in the form of the ontology, necessary relations between them were established. Besides, the ontology of maintenance testing also presents the general knowledge of the domain in the formal way. It was found, that the decision-making in the area can be easier with the help of ontology.

In view of the long data collection period of Army armored equipment maintenance and repair test data, this paper is devoted to researching the method of verifying the maintenance index in the case of small sample size, analyzing the historical distribution type of maintenance quantitative index, and constructing the SPRT based method. The equipment maintenance quantitative index test verification model, and the maintenance test based on the model, can achieve effective verification of the maintenance index under a small number of trials. The method is carried out to verify the method through historical experimental data. Under the premise of obtaining the same result, the number of tests is effectively reduced, which fully proves the scientificity of the method, and has the adjustment of equipment maintenance test plan and the whole development cycle setting. Important reference value.

In order to solve the problem that the sample maintenance test of the ship equipment is less in the maintenance test and evaluation work of the ship equipment, it is difficult to adopt the classical statistical method for the maintenance analysis and verification. The maintenance information of a ship is taken as the research object in this paper, the content and characteristics of the maintainable data sample set collected around the ship’s pilot phase, the maintenance information fusion research on the research equipment and similar equipment was carried out by the method of goodness of fit. By introducing bootstrap method to compensate for the errors caused by insufficient sample size, the process of using the goodness of fit method to fuse the ship’s research equipment and similar equipment maintainability information is sorted out. It provides theoretical methods and technical means to support the maintenance testing and evaluation of equipment.

With the continuous expansion of the campus area, the campus traffic problem is becoming increasingly serious. For example, the shortage of campus travel tools and the difficulty of students traveling, these problems need to be solved urgently. The emergence of shared travel tools will bring more convenience and choices to college students. This article has preliminarily analysed and inquired into the design and management mode of sharing travel tools for university campus. And in view of the traffic conditions in the campus, the solution is put forward by taking full consideration of the problems such as borrowing and stopping, driving mode, charging and endurance distance, maintenance testing and so on. A substitute tool that can be used in campus, convenient access and low cost will provide convenience for students to travel, reduce pressure for school traffic, and be more conducive to the construction of a low carbon and environmental protection campus culture.

Immersive virtual maintenance is a standard practice for the evaluation of material sustainability. New techniques of service evaluation rely largely on multiple samples collected by realistic on-site tests, and it is complex for them to incorporate valuable knowledge from immersive virtual maintenance, leading to a high expense of maintenance evaluation. This paper therefore proposes a weighted data fusion approach using the t-test and F-test for virtual simulation data and real-life test data, based on a product's multi-stage immersive virtual maintenance simulation studies. The virtual and real fusion samples is then periodically fused by the multistage Bayesian iteration fusion method. Then to iteratively fuse the simulated and actual fusion samples, the multistage Bayesian iteration fusion method is used. Finally, on the basis of the maximum posterior statistical analysis of the final functional on-site samples, the maintenance index values are found. The results of the simulation show that the proposed approach can effectively combine virtual and real multi-stage maintenance details, reduce the total number of on-site maintenance test samples, and obtain more detailed results for maintenance evaluation.

Georeferenced 3D models are an increasingly common choice to store and display urban data in many application areas. CityGML is an open and standardized data model, and exchange format that provides common semantics for 3D city entities and their relations and one of the most common options for this kind of information. Currently, creating and maintaining CityGML models is costly and difficult. This is in part because both the creation of the geometries and the semantic annotation can be complex processes that require at least some manual work. In fact, many publicly available CityGML models have errors. This paper proposes a method to facilitate the regular maintenance of correct city models in CityGML. This method is based on the continuous deployment strategy and tools used in software development, but adapted to the problem of creating, maintaining and deploying CityGML models, even when several people are working on them at the same time. The method requires designing and implementing CityGML deployment pipelines. These pipelines are automatic implementations of the process of building, testing and deploying CityGML models. These pipelines must be run by the maintainers of the models when they make changes that are intended to be shared with others. The pipelines execute increasingly complex automatic tests in order to detect errors as soon as possible, and can even automate the deployment step, where the CityGML models are made available to their end users. In order to demonstrate the feasibility of this method, and as an example of its application, a CityGML deployment pipeline has been developed for an example scenario where three actors maintain the same city model. This scenario is representative of the kind of problems that this method intends to solve, and it is based on real work in progress. The main benefits of this method are the automation of model testing, every change to the model is tested in a repeatable way; the automation of the model deployment, every change to the model can reach its end users as fast as possible; the systematic approach to integrating changes made by different people working together on the models, including the possibility of keeping parallel versions with a common core; an automatic record of every change made to the models (who did what and when) and the possibility of undoing some of those changes at any time. This work was supported by the Optimised Energy Efficient Design Platform for Refurbishment at District Level (OptEEmAL) project, Grant Agreement Number 680676, 2015-2019, as part of the European Union’s Horizon 2020 research and innovation programme.

Defense budget decreases in recent years with increasingly complex weapon systems and component equipment has mandated innovative support solutions to control costs. Automatic Test Systems (ATS) have been standardized by service branch in an effort to control the costs of support for support equipment. Support contracts with the ATS provider for repair services leveraged repair volume to reduce cost per repair. Support contracts where the ATS provider also supplies loaner spares used centralized wholesale spares systems to reduce retail spares requirements. Commitment to aggressive turnaround times for repairs reduced wholesale spares requirements. Entrusting the ATS provider with hardware configuration management improved system availability by allowing design improvements to address bad actor concerns. Industry has shown that the next logical step in the progression is leased support equipment, where system configuration management including both hardware and software configuration is entrusted to the ATS provider. The ATS OEM has unique knowledge about the hardware and software interactions in the system that allow efficient resolution of availability detractors like false alarms. The OEM understands instrument peculiarities allowing increasingly efficient fault detection and isolation. The costs associated with the improvements will be spread across the installed base so that each customer benefits from the increased availability, whether they have one system or hundreds. The unique requirements associated with leased equipment in a military operating environment will be explored. These steps explore only the horizontal axis of test, where the vertical axis includes all layers of test, such as design verification test, factory test, acceptance test, qualification test, at-platform maintenance test and off-platform maintenance test. The potential savings by reuse along the vertical axis include ATS and Test Programs Set (TPS) components. The factory test, acceptance test and off-platform performance test requirements are often very similar, if not exactly the same. The unique requirements associated with TPS reuse in a military environment will be explored.

Civil aircraft maintenance tests are used to detect latent failures in the Flight Control System (FCS) that cannot be detected through continuous monitoring. And each maintenance tests have their required exposure time intervals. The exposure time intervals are used to determine whether the maintenance tests will be executed automatically or manually. This Paper focused on the study of automated tests hosted in the FCS, which do not require the maintenance user intervention, and these tests will be automatically initiated following rollout phase. Automated tests are capable of commanding the primary surfaces and injecting failures into the FCS components, therefore they will be allowed to execute only when the aircraft is in a safe state. The suite of logic that manages and controls automated tests could contribute to hazardous or catastrophic hazards. This logic is referred as post flight and needs to be investigated to ensure the safety of the civil aircraft.

Testing is an inevitable process in safety critical applications such as avionics, space research, etc. In those systems, apart from manufacturing test, which is carried out after the chip is fabricated, maintenance testing also to be done in order to ensure that the device functionality remains the same. Digital circuits that are fabricated these days contain Built-in Self Test (BIST) arrangements with in the chip to perform the above said tasks. Since power consumption of the chip is crucial in battery operated electronic systems, reducing power in design and test circuits become mandatory. The proposed approach is allowed power LFSR using three ring oscillators and fuzzy logic concept. It reduces power consumption during test pattern generation and test response analysis processes by replacing the Linear Feedback Shift Register (LFSR) by its low power version. The proposed approach reduces power consumption up to 4.5% by dipping the number of switching activities in the circuit during the testing process.

In this chapter, we describe the calibration of three real engines in GasTurb performance models, using only measured data and information from the public domain. We recommend following a specific sequence of tasks and show that starting from relatively little input data the analysis evolves to make reliable performance predictions down to component level across a wide range of power settings and operating conditions. We describe in detail how to check the input data for consistency and create a Cycle Reference Point. The focus then moves to the compressor and turbine maps with advice on positioning the reference point in the map, scaling and finally modifying efficiency and speed. Equally important are the hints on how to implement information on active control items such as variable guide vanes or tip clearance systems. The engines modeled are the Pratt & Whitney J57, a two-spool turbojet run in an altitude test facility, the CFM56-3, a high bypass ratio turbofan run on a maintenance test bed and the Williams F107, a low bypass ratio turbofan with mixed exhaust and data taken from a specification.

This paper focuses on maintenance test flying as pertaining to commercial jet aircraft. Aircraft maintenance manuals or regulatory prescriptions require aircraft to be test flown prior to being released to service, following specific maintenance, repair, overhaul or modification events. Further, such flights might be conducted to accept or return aircraft as demonstration of their serviceability. Similarly, test flights to verify aircraft performance are at times required.Such maintenance test flights are mostly conducted by pilots rated to fly those aircraft primarily in commercial line operations, typically with no or little training on such specific maintenance or performance test flight procedures or techniques. The international regulatory environment remains in flux with discussion ongoing.In conducting such flights a pilot is exposed to activities outside the normal aircraft standard operating procedures up to the edge of the operational flight envelope. Whilst not intentional, abnormal aircraft behaviour can nevertheless result in inadvertent flight outside the envelope with a consequential potential loss of control. History has shown that the predominant cause of fatal accidents during maintenance test flying result from complex loss of control scenarios not recovered or not recoverable. This raises the question of adequacy of pilot training.Maintenance test flights are a necessary component for the industry to maintain its exceptional safety standards and minimising loss of life. But such flights in themselves remain demonstrably one or two orders of magnitude more risky than commercial flights.

devices and equipment have become very complex and are expected to operate under stringent environments. Equipment's should be properly maintained in order to fulfil their objectives. The signs of equipment's failure may not be apparent to clinical staff. Therefore they should be inspected periodically. Scheduled inspections help ensure the safety and efficacy of the medical equipment. A software tool is developed to implement a risk oriented prioritization of devices for equipment maintenance. First establishing an effective, efficient Computerized Preventive Maintenance Management System, collecting the data of equipments in laboratories and implement them to the system. The reports based on the inspection results, help determining a better maintenance's schedule.

The condition of no fault found (NFF) has been accepted by engineers and operators for many years. Whilst there are known general reasons for NFF one of the areas that is overlooked is the importance of the test equipment, whether built-in test equipment or automatic test equipment, and specifically the effectiveness of the test. How much of a system or component is actually being test by the test equipment? This paper explores the system or component fault coverage effectiveness and the impact on NFF. In doing so a module is proposed to establish the relationship between NFF and test coverage effectiveness for different reliabilities. As the component or system reliability improves along with the test effectiveness the percentage of NFF occurrences decreases. Another consideration is the assumed number of random failures that the design engineers include during the development phases. This is usually an underestimate and the combination of this and the ineffective fault coverage have a negative impact on the operational availability.

Systems Engineering (SE) allows addressing the design of complex systems from a holistic standpoint, starting from the early stage until the end of its lifetime. Using a SE approach, all the stakeholders’ needs can be considered, encompassing requirements coming from all the different fields connected to design. Adopting SE, the ranking of the proposed design alternatives can be carried out using Multi-Criteria Decision Making (MCDM) methods, which foresee the involvement in the decision-making process of a team of experts. Among MCDM methods, fuzzy-based ones could be advantageous whenever the decision-making process is mainly based on experts’ sensibility, because there is a lack of reliable quantitative information and/or the project is in the very early stage. This is the typical case of R&D activities on nuclear fusion, where big projects (ITER, DEMO) must contend with significant uncertainties. Therefore, a MCDM-based SE approach could help to improve the progress of these projects. Several applications are recalled in this paper and a further case study, regarding the Automated Inspection and Maintenance Test Unit (AIM-TU) concept design, is presented. In the framework of EU DEMO project, the AIM-TU has been proposed to provide to the international community a facility able to perform, with high reliability, robotic maintenance and inspection procedures in DEMO-oriented environments. In this paper the SE approach has been applied to the AIM-TU concept selection, adopting the fuzzy Analytic Hierarchy Process MCDM method for the best option selection. To this purpose, a novel fuzzy-based decision support tool named ELIGERE has been used.

The proliferation of Protection, Automation and Control Systems (PAC Systems) in the substations of the Portuguese electrical energy distribution grid, has brought many challenges to the Distribution System Operator (DSO), EDP Distribuicâo (EDPD), in terms of both project and maintenance. The recent technological boost of PAC Systems, is associated with the replacement of conventional system devices by Intelligent Electronic Devices (IEDs) and with the emergence of the IEC 61850 standard architecture and communications. The IEC 61850 standard brought new Substation Automation features, such as the Generic Object Oriented Substation Events (GOOSE) network messages, which are exchanged between IEDs. Nowadays, GOOSE messages and other IEC 61850 features, are fully tested in the development of a new PAC System and also during on-site commissioning, by manufacturers and integrators. However, given the progressive increase in the number of PAC Systems in operation according to the lEC 61850 architecture and protocols, these new tests are taking on greater importance and are increasingly required in the operation and maintenance phases of these systems. In this paper, a maintenance test model concerning IEC 61850 GOOSE functionalities is presented. A set of hardware and software test tools is selected and a simple model for the tests to be performed is developed. The main goal is to integrate the testing of GOOSE messages in the existent periodic and corrective maintenance procedures.

A model-based method for fault detection and early-stage isolation, applicable when unfaulty conditions can be identified only by a reduced number of trials (even only one), is presented. The basic idea is to model analytically the uncertainty of the unfaulty frequency response and express the fault condition in terms of the noise power variance. A preliminary fault isolation is carried out by sensitivity analysis in order to identify the most influencing model parameters and assess their influence on the estimated noise. Then, during maintenance tests, the noise power is checked to detect the faulty condition. This technique is conceived to check the quality of a critical component in an experimental installation (fault detection and early-stage isolation), as well as to detect its faulty dynamic behaviors over a long horizon maintenance test campaign (condition monitoring). The method was applied to four cold compressors with active magnetic bearings at CERN by proving to be able to detect an actual faulty condition in one of such compressors.

This paper extends an integrated model of production lot-sizing, maintenance and quality to consider the possibilities of inspection errors, inspection time and minimal repair for an imperfect process. These generalizations are importation because inspection might demand a considerable amount of time and there might be inspection errors due to human or technological limitations in the process of inspection. The production process is in either the in-control state or the out-of-controlstate. If the production process is judged in the in-control state, then when preventive maintenance is performed, system age and the level of maintenance performed will be related. If the production process is judged in the outof- control state, there might have two types. The fi rst type is a relatively mild production processshift, where minimal repair can restore the process to the in-control state. The second type is a more serious shift, where it interrupts the production cycle and the production has to be completely st...

Consider a Viable and Cost-Effective Platform for the Industries of the Future (IOF)Benefit from improved safety, performance, and product deliveries to your customers. Achieve a higher rate of equipment availability, performance, product quality, and reliability. Integrated Reliability: Condition Monitoring and Maintenance of Equipment incorporate

This investigation explores the influence of preventive maintenance error on production, inspection and cost. This study assumes that, given an imperfect production process, if preventive maintenance is performed after the inspection point is reached given a production process that is in an in-control state, correctness of maintenance performance will directly impact the inspection frequency, inspection interval, production quantity and cost benefit. In this study, numerical analysis is used to examine the influence of different levels of maintenance error with various non-conforming product rates on inspection frequency, inspection interval, production quantity and cost benefit, to optimize maintenance error values under different circumstances.

Success of manufacturing companies largely depends on reliability of their products. Scheduled maintenance is widely used to ensure that equipment is operating correctly so as to avoid unexpected breakdowns. Such maintenance is often carried out separately for every component, based on its usage or simply on some fixed schedule. However, scheduled maintenance is labor-intensive and ineffective in identifying problems that develop between technician's visits. Unforeseen failures still frequently occur. In contrast, predictive maintenance techniques help determine the condition of in-service equipment in order to predict when and what repairs should be performed. The main goal of predictive maintenance is to enable pro-active scheduling of corrective work, and thus prevent unexpected equipment failures.

The real-time maintenance sensor for the active reflector is one of the key technologies for the active reflector upgradation plan of 13.7m millimeter radio telescope from Purple Mountain Observatory, China. A new type of maintenance integration sensor based on PSD and laser module based on normal angle and distance detection is proposed in this paper. After the brief introduction of the maintenance theory of the radio telescope segmented primary reflector, the method is simulated and tested on the real backup panel from the telescope in the active reflector lab in Nanjing Institute of Astronomical Optics and Technology, China. The method is proved to be a high accurate, engineering feasible for that real-time maintenance of the whole primary. Finally some conclusions are reached.

Combinatorial test design (CTD) is an effective test design technique that reveals faults resulting from parameter interactions in a system. CTD requires a test space definition in the form of a set of parameters, their respective values, and restrictions on the value combinations. Though CTD is considered an industry best practice, there is only a small body of work on the practical application of CTD to industrial systems, and some key elements of the CTD application process are under-explored. Specifically, little consideration has been given to the process for identifying the parameters of the test space and their interrelations, how to validate the test space definition remains an open question, the application of CTD in reported work concentrates mostly on function or interface level testing and is hardly expanded to other levels of testing, and there is a significant lack of evaluation of the degree to which CTD helped improve the quality of the system under test. In this work, we analyze the continuous application of CTD in system test of two large industrial systems: IBM® POWER7® and IBM® System z®. For POWER7, CTD was used to design test cases for server concurrent maintenance. The application of CTD was in direct response to inconsistent reliability of those features on the prior POWER6® servers, and resulted in noteworthy quality improvements on POWER7. Success with POWER7 led to application of the methods to System z Enhanced Driver Maintenance testing, also featured in this work. To the best of our knowledge, this is the first comprehensive analysis of CTD usage in system test of industrial products, and the first analysis of long term use of CTD. We describe the methodology that we followed to define the combinatorial test space, while answering some unique challenges rising from the use of CTD to design functional test cases at system level rather than at interface or function level. We also describe our methodology for evaluating the test space definition and continuously improving it over time. In addition, we describe advanced CTD features that we found helpful for achieving an effective yet affordable test plan. Finally, we quantitatively and qualitatively evaluate the overall effectiveness of CTD usage, and show that it resulted in significantly improved server concurrent maintenance features.

This paper presents an off-line diagnosis strategy for parallel message-passing systems. This strategy, called host-diagnosis, allows a host system to perform centralized diagnosis of the system state, given results of distributed tests performed among the system processors. It is useful for a manufacturing or a maintenance test. Three algorithms that use the host-diagnosis strategy are proposed. Their performance are evaluated using a queuing network model and compared to those of a classic distributed self-diagnosis algorithm. Obtained results show important diagnosis latency savings in case of host-diagnosis algorithms in comparison with the self-diagnosis algorithm.

The current study proposes a intelligent maintenance decision-making system is as a fixed equipment maintenance strategies assessment system. Because the maintenance decision-making is based on monitoring of equipment damage state and risk in the system, the system is established on the distributed database and internet technology. Moreover, different maintenance strategies, such as corrective, preventive, and predictive maintenance strategies after periodic and in-service inspections, are determined according to equipment failure consequences and risks. According to the data in the risk database and damage state database, the decision-making regards the "System" as a decision-making object and performs the risk-concentrated analysis, the operational cycle after maintenance and cost-effective maintenance assessment, where the multi-objective optimization of maintenance strategies on safety, availability, and economic efficiency is accomplished.

Equipment maintenance support is the most important influencing factor which affects weapon battle ability. Equipment maintenance support capability evaluation result can be used as steering for equipment maintenance blue print configuration. Based on analysis of equipment maintenance support, maintenance evaluation guide line is discussed in paper. Then neural network-based equipment maintenance support evaluation model is established. BP dynamic neural network is applied in constructing model and the amelioration weight reset arithmetic is imported in equipment maintenance support evaluation model. According to evaluation arithmetic, equipment maintenance support evaluation center computes evaluation result. Weapon equipment development department and army can optimize maintenance support scheme based on evaluation result and maintain equipment. At last service-oriented software development method is used to develop neural network-based equipment maintenance expert system. Decision-makers can establish rational maintenance scenario according to evaluation result and arrange maintenance tasks.

The ATS Framework Working Group focuses on identifying commercial standards that are not only acceptable to the needs of the DoD, but to industry as well. Therefore, the group is tasked with supporting, evaluating, and demonstrating the ability of the standards to meet the ATS Framework goals and objectives. Of particular interest to this paper is the ATS key element Maintenance Test Data and Services (MTDS). This key element addresses a need to share information across maintenance levels and across DoD / Industry ATS. The current information structures are often Service or platform dependant. Even though these systems do a good job of providing a logistics infrastructure, they seldom share information back to the maintenance chain or across platforms and Services. The sharing of this information is essential in performing complex and sophisticated diagnostics over the product's life cycle. Given a standard set of definitions and data formats, information may be shared among all users who have implemented the standard data content and format.

The Automatic Test System (ATS) Executive Directorate (ED) is charged with developing objectives for the Department of Defense (DoD) ATS modernization. The DoD ATS Framework Working Group (FWG) was established by the ATS ED to create a Framework addressing these objectives. The FWG consists of two sub-groups; Management, that includes members from all of the DoD Services, and Technical. The Framework is made up of key elements and associated specifications and standards that form the open system architecture approach for DoD ATSs. In addition to creating and updating key element definitions, the FWG focuses on identifying commercial ATS related specifications that might satisfy the elements in the Framework. The standards specified in the DoD ATS Framework are documented in the DoD's Information Technology Standards Repository (DISR) and thereby become a mandatory requirement for all DoD ATS acquisitions. The Framework is also being specifically called out in DoD ATS requirements documents so that its standards are incorporated in future DoD ATS acquisitions, such as the Navy's eCASS. Although the ATS Framework was originally defined more than 10 years ago, it continues to evolve as test technology evolves. A function of the FWG is to continually assess the Framework and plan the development and demonstration of specifications and standards to satisfy ATS Framework requirements. The FWG is currently participating in the standards development process via standards organizations, consortia, and working groups. The FWG is evaluating these standards in terms of applicability to the twenty plus key elements defined in the Framework. The FWG is also continually evaluating new test and information technologies to further refine and add new key elements. When necessary, the FWG provides requirements and potential solutions to standards development teams so that the resulting standard will fit within the Framework. When these standards are published and proven to meet the requirements of a particular Framework element, the FWG makes recommendations to the DoD's ATS Management Board (AMB) regarding how these standards should be represented in the DISR. Standards which are mandated will be required by the acquisition process, and vendors' products acquired by the DoD must conform to them. This paper will provide a summary of the current activities and issues impacting the ATS Framework with a discussion of the near term plans of the FWG. It will provide status on the key elements that the FWG members are currently working on. These elements include the Adapter Functional and Parametric Data (AFP), Diagnostic Data (DIAD), Diagnostic Services (DIAS), Instrument Functional and Parametric Data (IFP), Master Conformance Index (MCI), Maintenance Test Data (MTD), Resource Adapter Interface (RAI), Run Time Services (RTS), Prognostics and Health Management (PHM), and Test Station Functional and Parametric Data (TSFP). The standards that satisfy or partially satisfy these key elements, and the current status of these standards are discussed. The paper also describes the purpose of, and the FWG's role in, several industry working groups; including LAN extensions for Instrumentation (LXI), Institute of Electrical and Electronics Engineers (IEEE) Standards Coordinating Committee 20 (SCC20), Interchangeable Virtual Instruments (IVI), and Synthetic Instruments Working Group (SIWG). Finally, current issues, such as how signal modeling is to be incorporated within the Framework, the relationship to the DoD's efforts with those of the UK Ministry of Defense (MoD), the use of the DISR mandated elements in upcoming DoD ATS acquisitions, and how O-level test capabilities could be incorporated in the Framework are discussed.

Aiming at the problem that the condition information of the equipment in power plant is seldom considered during making maintenance decision and as a result insufficiency or surplus of maintenance occurs often, a model of condition based maintenance decision is proposed. Based on system division, the criticality of equipment in same level is evaluated and maintenance strategies of equipment are decided based on the criticality index. To the equipment using condition based maintenance strategy, the condition is evaluated and predicted by fully using the operating parameters, condition monitoring parameters and the residual life is estimated. To minimize the maintenance cost of the equipment in same subsystem, a decision tree algorithm is used, in which equipment condition, logistic support constraints, life cycle profit, and equipment dependencies are considered. The method is applied to the feed water subsystem of a thermal power plant. It is shown by the instance that this method is feasible and effective, and it can be used as a technical support next in realizing condition-based maintenance.

ISBN: 0818608676; An original BIST (built-in self-test) scheme is proposed to cover some shortcomings of self-checking circuits and to ensure all tests needed for integrated circuits. In the BIST scheme, self-checking techniques and built-in self-test techniques are combined in an original way and take advantage one from the other. This results in a unified BIST scheme (UBIST), allowing a high fault coverage for all tests needed for integrated circuits, e.g. offline test (design verification, manufacturing test, and maintenance test) and online concurrent error detection.

As software maintenance requirements continue to grow, conflicting with demands for new development, managers must continually evaluate the cost effectiveness of various maintenance strategies. He shows that one can measure and use a significant benefit from maintenance-the reduction in failure risk-to evaluate maintenance strategies. The ability to measure the differential risk of failure in modules within a system can be used to design high-risk-first maintenance strategies and to motivate the effort. Moreover, maintenance's impact on failure risk can demonstrate whether it is advantageous to fix errors as soon as they are found or perform scheduled maintenance in the future. Failure risk assessments can also be used to measure the effectiveness of perfective maintenance strategies. Not only can this type of maintenance be justified, but alternative strategies can be compared to determine which will minimize failure risk. >

Automatic routine execution (REx) testing of telecommunications switching equipment is often performed to improve system reliability, and to check the operational status of communications equipment. For duplex equipment REx testing, at a minimum, periodically checks the inactive unit for problems. If problems are found, then repairs can be made before service is impacted. In addition to this clear benefit, there are also costs associated with testing. Equipment that is being extensively tested may not be in-service, and the testing itself can lead to two types of incorrect conclusions, conclusions that lead to either unnecessary repairs, or to a dangerous misperception that the equipment is working properly. The first type of incorrect conclusion is a false positive. The second is a false negative. Since there are both costs and benefits associated with REx testing, it is natural to conclude that REx tests should be run neither too frequently nor too infrequently. In this paper we develop a detailed reliability model of a generic duplex peripheral module. The term generic is used, since the intent is to provide a useful methodology with some results that are independent of specific equipment, provided by various manufacturers. The model shows that picking the correct REx testing frequency results in significant savings in downtime. The impact on system outages as a function of REx testing frequency is shown for a number of cases.

In recent years conventional DC testing of installed insulation has begun to lose favor. The authors present a novel technique that overcomes all previous objections to DC testing and many of the disadvantages, such as size and weight, of the already identified alternatives. The power supply, called a pulsed resonant power supply, produces line frequency output with no DC content. There is no switching involved; hence the supply is readily adaptable for partial discharge and power factor measurements. With its many attributes, the pulsed resonant power supply is well suited for maintenance testing of large rotating machines. >