The Experts below are selected from a list of 9573 Experts worldwide ranked by ideXlab platform
Christian Ferdinand - One of the best experts on this subject based on the ideXlab platform.
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an abstract interpretation based timing validation of hard real time avionics software
Dependable Systems and Networks, 2003Co-Authors: Stephan Thesing, Jean Souyris, Reinhold Heckmann, F Randimbivololona, Marc Langenbach, Reinhard Wilhelm, Christian FerdinandAbstract:Hard real-time avionics systems like flight control software are expected to always react in time. Consequently, it is essential for the timing validation of the software that the worst-case execution time (WCET) of all tasks on a given hardware configuration be known. Modern processor components like caches, Pipelines, and branch prediction complicate the determination of the WCET considerably since the execution time of a single instruction may depend on the execution history. The safe, yet overly pessimistic assumption of no cache hits, no overlapping executions in the processor Pipeline, and constantly mispredicted branches results in a serious overestimation of the WCET. Our approach to WCET prediction was implemented for the Motorola ColdFire 5307. It includes a static prediction of ∗ This work was partly supported by the RTD project IST-1999-20527 “DAEDALUS” of the European FP5 program. cache and Pipeline Behavior, producing much tighter upper bounds for the execution times. The WCET analysis tool works on real applications. It is safe in the sense that the computed WCET is always an upper bound of the real WCET. It requires much less effort, while producing more precise results than conventional measurement-based methods.
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Pipeline Behavior prediction for superscalar processors by abstract interpretation
Languages Compilers and Tools for Embedded Systems, 1999Co-Authors: Jorn Schneider, Christian FerdinandAbstract:For real time systems not only the logical function is important but also the timing Behavior, e. g. hard real time systems must react inside their deadlines. To guarantee this it is necessary to know upper bounds for the worst case execution times (WCETs). The accuracy of the prediction of WCETs depends strongly on the ability to model the features of the target processor.Cache memories, Pipelines and parallel functional units are architectural components which are responsible for the speed gain of modern processors. It is not trivial to determine their influence when predicting the worst case execution time of programs.This paper describes a method to predict the Behavior of Pipelined superscalar processors and reports initial results of a prototypical implementation for the SuperSPARC I processor.
R J Mair - One of the best experts on this subject based on the ideXlab platform.
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tunneling beneath buried pipes view of soil strain and its effect on Pipeline Behavior
Journal of Geotechnical and Geoenvironmental Engineering, 2010Co-Authors: Alec M Marshall, Assaf Klar, R J MairAbstract:The paper examines the problem of tunneling beneath buried Pipelines and the relationship between soil strains and Pipeline bending Behavior. Data are presented from centrifuge tests in which tunnel volume loss was induced in sand beneath Pipelines of varying stiffness properties. The model tunnel and Pipelines were all placed at a Perspex wall of the centrifuge strong box such that image-based deformation analyses could be performed. The method provided detailed data of subsurface soil and pipe displacements and illustrated the soil-pipe interaction mechanisms that occurred during tunnel volume loss, including the formation of a gap beneath the pipes. The relationship between tunnel volume loss, soil strain, and pipe bending Behavior is illustrated. Experimental results of pipe bending moments are compared against predictions: (1) assuming the pipe simply follows greenfield displacements; (2) using an elastic continuum solution; and (3) using a new method in which an "out-of-plane" shear argument, due to soil-pipe interaction, is introduced into the elastic continuum solution. It is shown that the new method gives the best prediction of experimental pipe bending moments.
Alec M Marshall - One of the best experts on this subject based on the ideXlab platform.
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tunneling beneath buried pipes view of soil strain and its effect on Pipeline Behavior
Journal of Geotechnical and Geoenvironmental Engineering, 2010Co-Authors: Alec M Marshall, Assaf Klar, R J MairAbstract:The paper examines the problem of tunneling beneath buried Pipelines and the relationship between soil strains and Pipeline bending Behavior. Data are presented from centrifuge tests in which tunnel volume loss was induced in sand beneath Pipelines of varying stiffness properties. The model tunnel and Pipelines were all placed at a Perspex wall of the centrifuge strong box such that image-based deformation analyses could be performed. The method provided detailed data of subsurface soil and pipe displacements and illustrated the soil-pipe interaction mechanisms that occurred during tunnel volume loss, including the formation of a gap beneath the pipes. The relationship between tunnel volume loss, soil strain, and pipe bending Behavior is illustrated. Experimental results of pipe bending moments are compared against predictions: (1) assuming the pipe simply follows greenfield displacements; (2) using an elastic continuum solution; and (3) using a new method in which an "out-of-plane" shear argument, due to soil-pipe interaction, is introduced into the elastic continuum solution. It is shown that the new method gives the best prediction of experimental pipe bending moments.
Nobu Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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a new verification methodology for complex Pipeline Behavior
Design Automation Conference, 2001Co-Authors: Kazuyoshi Kohno, Nobu MatsumotoAbstract:A new test program generation tool, MVpGen, is developed for verifying Pipeline design of microprocessors. The only inputs MVpGen requires are Pipeline-Behavior specifications; it automatically generates test cases at first from Pipeline-Behavior specifications and then automatically generates test programs corresponding to the test cases. Test programs for verifying complex Pipeline Behavior such as hazard and branch or hazard and exception, are generated. mVpGen has been integrated into a verification system for verifying RTL descriptions of a real microprocessor design and complex bugs that remained hidden in the RTL descriptions are detected.
Assaf Klar - One of the best experts on this subject based on the ideXlab platform.
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tunneling beneath buried pipes view of soil strain and its effect on Pipeline Behavior
Journal of Geotechnical and Geoenvironmental Engineering, 2010Co-Authors: Alec M Marshall, Assaf Klar, R J MairAbstract:The paper examines the problem of tunneling beneath buried Pipelines and the relationship between soil strains and Pipeline bending Behavior. Data are presented from centrifuge tests in which tunnel volume loss was induced in sand beneath Pipelines of varying stiffness properties. The model tunnel and Pipelines were all placed at a Perspex wall of the centrifuge strong box such that image-based deformation analyses could be performed. The method provided detailed data of subsurface soil and pipe displacements and illustrated the soil-pipe interaction mechanisms that occurred during tunnel volume loss, including the formation of a gap beneath the pipes. The relationship between tunnel volume loss, soil strain, and pipe bending Behavior is illustrated. Experimental results of pipe bending moments are compared against predictions: (1) assuming the pipe simply follows greenfield displacements; (2) using an elastic continuum solution; and (3) using a new method in which an "out-of-plane" shear argument, due to soil-pipe interaction, is introduced into the elastic continuum solution. It is shown that the new method gives the best prediction of experimental pipe bending moments.