The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform

J Lawless - One of the best experts on this subject based on the ideXlab platform.

  • On a scheme for predictive maintenance
    European Journal of Operational Research, 2007
    Co-Authors: Martin Crowder, J Lawless
    Abstract:

    An operating system contains a replaceable unit whose wear (i.e. accumulated amount of damage) can be observed over time. When the wear reaches a certain level the unit is no longer able to function satisfactorily and needs to be replaced. Although units are produced to the same Nominal Specification there is still some random variation among them in their wear rates. This will be expressed by incorporating a random effect, or frailty term, in the model for individual degradation. There are costs for observing the wear on a unit, for replacing a unit, and for allowing a unit to fail before being replaced. When the last cost is comparatively large replacement before failure is preferable. For some standard examples of wear processes the lifetime distributions are obtained and the cost consequences of particular maintenance schemes are investigated.

  • On a scheme for predictive maintenance
    European Journal of Operational Research, 2007
    Co-Authors: Martin Crowder, J Lawless
    Abstract:

    An operating system contains a replaceable unit whose wear (i.e. accumulated amount of damage) can be observed over time. When the wear reaches a certain level the unit is no longer able to function satisfactorily and needs to be replaced. Although units are produced to the same Nominal Specification there is still some random variation among them in their wear rates. This will be expressed by incorporating a random effect, or frailty term, in the model for individual degradation. There are costs for observing the wear on a unit, for replacing a unit, and for allowing a unit to fail before being replaced. When the last cost is comparatively large replacement before failure is preferable. For some standard examples of wear processes the lifetime distributions are obtained and the cost consequences of particular maintenance schemes are investigated. © 2005 Elsevier B.V. All rights reserved.

Abbas Tarhini - One of the best experts on this subject based on the ideXlab platform.

  • Robustness testing of composed real-time systems
    2010
    Co-Authors: Hacène Fouchal, Antoine Rollet, Abbas Tarhini
    Abstract:

    In this paper, we suggest a methodology for testing robustness of Real-Time Component-Based Systems (RTCBS). A RTCBS system is described as a collection of components where each component is modeled as a Timed Input-Output Automaton (TIOA). For each component, we handle two Specifications: a Nominal one and a degraded one. We extract test sequences from the Nominal Specification and we inject automatically faults in order to model hostile environments. Then we present an adequate test architecture consisting of the System Under Test (SUT) of components, and a distributed tester that consists of a set of coordinating testers. Each tester is dedicated to test a single SUT component. A test execution algorithm is presented. Testing the SUT is divided into two phases. In the first phase, the tester executes the generated test sequences of each component in isolation and records the feedback of this experimentation. The robustness is checked by verifying if the recorded results are accepted by the degraded Specification of each component. If all components are robust according to the inserted hazards, we check the robustness of communications between components respecting the same process described before.

  • Robustness testing of composed real-time
    2010
    Co-Authors: Antoine Rollet, Abbas Tarhini
    Abstract:

    In this paper, we suggest a methodology for testing robustness of Real-Time Component-Based Systems (RTCBS). A RTCBS system is described as a collection of components where each component is modeled as a Timed Input-Output Automaton (TIOA). For each component, we handle two Specifications: a Nominal one and a degraded one. We extract test sequences from the Nominal Specification and we inject autom atically faults in order to model hostile environments. Then we present an adequate test architecture consisting of the Sys tem Under Test (SUT) of components, and a distributed tester that consists of a set of coordinating testers. Each tester is ded icated to test a single SUT component. A test execution algorithm is presented. Testing the SUT is divided into two phases. In the first phase, the tester executes the generated test sequence s of each component in isolation and records the feedback of this experimentation. The robustness is checked by verifying if the recorded results are accepted by the degraded Specification of each co mponent. If all components are robust according to the inserted hazards, we check the robustness of communications between components respecting the same process described before.

  • AICT/ICIW - Robustness evaluation of real-Time Protocols
    Advanced Int'l Conference on Telecommunications and Int'l Conference on Internet and Web Applications and Services (AICT-ICIW'06), 2006
    Co-Authors: Abbas Tarhini, Hacène Fouchal
    Abstract:

    In this paper, we suggest a methodology for measuring the degree of robustness for Real-Time Component-Based Systems (RTCBS). Each component of the RTCBS system is modeled as a Timed Labeled Transition System (TLTS). For each component, we handle two Specifications : a Nominal one and a degraded one. We extract test sequences from the Nominal Specification and we inject automatically faults in order to model hostile environments. A quantitative system is presented. It measures the degree of robustness of the RTCBS based on the robustness of the value of events and transition and also the robustness of their timing constraints. Then we present an adequate test architecture consisting of the System Under Test (SUT), and a distributed tester that consists of a set of coordinating testers. A test execution algorithm is also presented. Testing the SUT is divided into two phases that tests the robustness of each component and the robustness of the communication between them

  • SOFSEM - Robustness of composed timed systems
    SOFSEM 2005: Theory and Practice of Computer Science, 2005
    Co-Authors: Hacène Fouchal, Antoine Rollet, Abbas Tarhini
    Abstract:

    In this study we present a technique for testing robustness of Real-time systems described as Component-Based System having timing constraints. Each component is modeled as a Timed Input-Output Automaton (TIOA). For robustness issue, we handle two Specifications : a Nominal one (the more detailed Specification) and a degraded one (considering only vitale functionnalities). We derive test sequences from the Nominal Specification of each component. We proceed to a mutation technique on these sequences in order to simulate hostile environments. Then we present a detailled algorithm for the application of test sequences on the Implementation of the system. This is done by means of an adequate test architecture consisting of the Implementation Under Test (IUT) of components, and a distributed tester that consists of a set of coordinating testers. Each tester is dedicated to test a single component.

  • AICCSA - A pragmatic approach for testing robustness on real-time component based systems
    The 3rd ACS IEEE International Conference onComputer Systems and Applications 2005., 2005
    Co-Authors: Abbas Tarhini, A. Rollet, Hacène Fouchal
    Abstract:

    Summary form only given. In this paper, we suggest a realistic methodology for testing robustness of real-time component-based systems (RTCBS). A RTCBS system is described as a collection of components where each component is specified by a Nominal and a degraded Specification, modeled as a timed input-output automaton (TIOA). Further, the communication of the whole system is also specified by its Nominal and degraded Specification. We extract test sequences from the Nominal Specification and we inject automatically faults in order to model hostile environments. Then, we present an adequate test architecture consisting of the system under test (SUT) of components, and a distributed tester that consists of a set of coordinating testers. Each tester is dedicated to test a single SUT component. A test execution algorithm with an approach to handle testers coordination and execution delay is presented. Testing the SUT is divided into two phases. In the first phase, the tester tests the robustness of each component in isolation. If all components are robust according to the inserted hazards, in the second phase, we use the Nominal and degraded Specification of the whole system to check the robustness of communications between components.

Martin Crowder - One of the best experts on this subject based on the ideXlab platform.

  • On a scheme for predictive maintenance
    European Journal of Operational Research, 2007
    Co-Authors: Martin Crowder, J Lawless
    Abstract:

    An operating system contains a replaceable unit whose wear (i.e. accumulated amount of damage) can be observed over time. When the wear reaches a certain level the unit is no longer able to function satisfactorily and needs to be replaced. Although units are produced to the same Nominal Specification there is still some random variation among them in their wear rates. This will be expressed by incorporating a random effect, or frailty term, in the model for individual degradation. There are costs for observing the wear on a unit, for replacing a unit, and for allowing a unit to fail before being replaced. When the last cost is comparatively large replacement before failure is preferable. For some standard examples of wear processes the lifetime distributions are obtained and the cost consequences of particular maintenance schemes are investigated.

  • On a scheme for predictive maintenance
    European Journal of Operational Research, 2007
    Co-Authors: Martin Crowder, J Lawless
    Abstract:

    An operating system contains a replaceable unit whose wear (i.e. accumulated amount of damage) can be observed over time. When the wear reaches a certain level the unit is no longer able to function satisfactorily and needs to be replaced. Although units are produced to the same Nominal Specification there is still some random variation among them in their wear rates. This will be expressed by incorporating a random effect, or frailty term, in the model for individual degradation. There are costs for observing the wear on a unit, for replacing a unit, and for allowing a unit to fail before being replaced. When the last cost is comparatively large replacement before failure is preferable. For some standard examples of wear processes the lifetime distributions are obtained and the cost consequences of particular maintenance schemes are investigated. © 2005 Elsevier B.V. All rights reserved.

Hacène Fouchal - One of the best experts on this subject based on the ideXlab platform.

  • Robustness testing of composed real-time systems
    2010
    Co-Authors: Hacène Fouchal, Antoine Rollet, Abbas Tarhini
    Abstract:

    In this paper, we suggest a methodology for testing robustness of Real-Time Component-Based Systems (RTCBS). A RTCBS system is described as a collection of components where each component is modeled as a Timed Input-Output Automaton (TIOA). For each component, we handle two Specifications: a Nominal one and a degraded one. We extract test sequences from the Nominal Specification and we inject automatically faults in order to model hostile environments. Then we present an adequate test architecture consisting of the System Under Test (SUT) of components, and a distributed tester that consists of a set of coordinating testers. Each tester is dedicated to test a single SUT component. A test execution algorithm is presented. Testing the SUT is divided into two phases. In the first phase, the tester executes the generated test sequences of each component in isolation and records the feedback of this experimentation. The robustness is checked by verifying if the recorded results are accepted by the degraded Specification of each component. If all components are robust according to the inserted hazards, we check the robustness of communications between components respecting the same process described before.

  • AICT/ICIW - Robustness evaluation of real-Time Protocols
    Advanced Int'l Conference on Telecommunications and Int'l Conference on Internet and Web Applications and Services (AICT-ICIW'06), 2006
    Co-Authors: Abbas Tarhini, Hacène Fouchal
    Abstract:

    In this paper, we suggest a methodology for measuring the degree of robustness for Real-Time Component-Based Systems (RTCBS). Each component of the RTCBS system is modeled as a Timed Labeled Transition System (TLTS). For each component, we handle two Specifications : a Nominal one and a degraded one. We extract test sequences from the Nominal Specification and we inject automatically faults in order to model hostile environments. A quantitative system is presented. It measures the degree of robustness of the RTCBS based on the robustness of the value of events and transition and also the robustness of their timing constraints. Then we present an adequate test architecture consisting of the System Under Test (SUT), and a distributed tester that consists of a set of coordinating testers. A test execution algorithm is also presented. Testing the SUT is divided into two phases that tests the robustness of each component and the robustness of the communication between them

  • SOFSEM - Robustness of composed timed systems
    SOFSEM 2005: Theory and Practice of Computer Science, 2005
    Co-Authors: Hacène Fouchal, Antoine Rollet, Abbas Tarhini
    Abstract:

    In this study we present a technique for testing robustness of Real-time systems described as Component-Based System having timing constraints. Each component is modeled as a Timed Input-Output Automaton (TIOA). For robustness issue, we handle two Specifications : a Nominal one (the more detailed Specification) and a degraded one (considering only vitale functionnalities). We derive test sequences from the Nominal Specification of each component. We proceed to a mutation technique on these sequences in order to simulate hostile environments. Then we present a detailled algorithm for the application of test sequences on the Implementation of the system. This is done by means of an adequate test architecture consisting of the Implementation Under Test (IUT) of components, and a distributed tester that consists of a set of coordinating testers. Each tester is dedicated to test a single component.

  • AICCSA - A pragmatic approach for testing robustness on real-time component based systems
    The 3rd ACS IEEE International Conference onComputer Systems and Applications 2005., 2005
    Co-Authors: Abbas Tarhini, A. Rollet, Hacène Fouchal
    Abstract:

    Summary form only given. In this paper, we suggest a realistic methodology for testing robustness of real-time component-based systems (RTCBS). A RTCBS system is described as a collection of components where each component is specified by a Nominal and a degraded Specification, modeled as a timed input-output automaton (TIOA). Further, the communication of the whole system is also specified by its Nominal and degraded Specification. We extract test sequences from the Nominal Specification and we inject automatically faults in order to model hostile environments. Then, we present an adequate test architecture consisting of the system under test (SUT) of components, and a distributed tester that consists of a set of coordinating testers. Each tester is dedicated to test a single SUT component. A test execution algorithm with an approach to handle testers coordination and execution delay is presented. Testing the SUT is divided into two phases. In the first phase, the tester tests the robustness of each component in isolation. If all components are robust according to the inserted hazards, in the second phase, we use the Nominal and degraded Specification of the whole system to check the robustness of communications between components.

Fredrik Edelvik - One of the best experts on this subject based on the ideXlab platform.

  • GEOMETRY ASSURANCE INTEGRATING PROCESS VARIATION WITH SIMULATION OF SPRING-IN FOR COMPOSITE PARTS AND ASSEMBLIES
    Journal of Computing and Information Science in Engineering, 2016
    Co-Authors: Cornelia Jareteg, Kristina Wärmefjord, Christoffer Cromvik, Rikard Söderberg, Lars Lindkvist, Johan S. Carlson, Stig Larsson, Fredrik Edelvik
    Abstract:

    Copyright © 2016 by ASME.Geometrical variation and deviation in all the manufacturing processes affect the quality of the final product. Therefore, geometry assurance is an important tool in the design phase of a new product. In the automotive and aviation industries where the use of composite parts is increasing drastically, new tools within variation simulations are needed. Composite parts tend to deviate more from Nominal Specification compared to metal parts. Methods to simulate the manufacturing process of composites have been developed before. In this paper, we present how to combine the process variation simulation of composites with traditional variation simulations. The proposed method is demonstrated on a real complex subassembly, representing part of an aircraft wing-box. Since traditional variation simulation methods are not able to capture the spring-in and the special deviation behavior of composites, the proposed method adds a new feature and reliability to the geometry assurance process of composite assemblies.

  • Geometry Assurance Integrating Process Variation With Simulation of Spring-In for Composite Parts and Assemblies
    Volume 2A: Advanced Manufacturing, 2014
    Co-Authors: Cornelia Jareteg, Kristina Wärmefjord, Christoffer Cromvik, Rikard Söderberg, Lars Lindkvist, Johan S. Carlson, Stig Larsson, Fredrik Edelvik
    Abstract:

    Geometrical variation and deviation in all manufacturing processes affect quality of the final product. Therefore geometry assurance is an important tool in the design phase of a new product. In the automotive and aviation industries where the use of composite parts is increasing drastically, new tools within variation simulations are needed. Composite parts tend to deviate more from Nominal Specification compared to metal parts. Methods to simulate the manufacturing process of composites have been developed before. In this paper we present how to combine the process variation simulation of composites with traditional variation simulations. The proposed method is demonstrated on a real complex subassembly, representing part of an aircraft wing-box. Since traditional variation simulation methods are not able to capture the spring-in and the special deviation behavior of composites,the proposed method adds a new feature and reliability to the geometry assurance process of composite assemblies.