This article outlines a graphical software package for performance and dependability modeling with deterministic and stochastic Petri nets (DSPNs). The package is called DSPNexpress because its main scientific contrib...
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This article outlines a graphical software package for performance and dependability modeling with deterministic and stochastic Petri nets (DSPNs). The package is called DSPNexpress because its main scientific contribution lies in its efficient numerical solution component. The development of DSPNexpress has been motivated by the lack of a software package for an efficient numerical analysis of Deterministic and stochastic Petri nets (DSPNs) and the complexity requirements imposed by evaluating design alternatives for hardware and software components of multicomputer systems. The main scientific contribution of DSPNexpress lies in its efficient numerical solution component. The version 1.3 of DSPNexpress solves complex DSPNs with four orders of magnitude less CPU time than the previously known numerical method. As a consequence, DSPNexpress is able to calculate steady-state solutions of complex DSPNs with reasonable computational effort on a modern workstation (e.g. a DSPN with 100000 tangible marking and 5000000 state transitions with mild stiffness can be solved in 1 hour of CPU time on a Sun Spare station 2). The article summarizes the main innovative features of the software package DSPNexpress.
Critical embedded systems need a dependable operating system and application. Despite all efforts to prevent and remove faults in system development, residual software faults usually persist. Therefore, critical syste...
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Critical embedded systems need a dependable operating system and application. Despite all efforts to prevent and remove faults in system development, residual software faults usually persist. Therefore, critical systems need some sort of fault tolerance to deal with these faults and also with hardware faults at operation time. This work proposes fault-tolerant support mechanisms for the BOSS embedded operating system, based on the application of proven fault tolerance strategies by middleware control software which transparently delivers the added functionality to the application software. Special attention is taken to complexity control and resource constraints, targeting the needs of the embedded market
Low temperature cofiring ceramic (LTCC) combines hybrid technology, biocompatibility, chemical resistance and ease of fabrication to serve as a construction material for microfluidics. Due to the lack of CAD tools for...
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Low temperature cofiring ceramic (LTCC) combines hybrid technology, biocompatibility, chemical resistance and ease of fabrication to serve as a construction material for microfluidics. Due to the lack of CAD tools for MEMS this paper applies a model for the description of stationary flow in LTCC channels of non circular cross sections. Sample devices for validation are fabricated by laser structuring and standard LTCC process. The substrates consist of 130 mum thick layers and are connected horizontally to a tubing system. Characteristic length scales range between 131 mum and 159 mum. Deviations stay within the assumed uncertainty and confirm the theory. Results show that applying solutions of geometry description in accepted fluid mechanics models gives an appropriate tool for flow description. Implementing the model as a network description in the describing language MOSILAB can allow dimensioning and optimization under functional restrictions, e.g. pressure drop or geometry as well as communication with other modeling tools
We point out some errors in the combinatorial approach for the steady-state analysis of a deterministic and stochastic Petri net (DSPN) presented by M. Lu, D. Zhang, and T. Murata (1990). However, the methodology for ...
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We point out some errors in the combinatorial approach for the steady-state analysis of a deterministic and stochastic Petri net (DSPN) presented by M. Lu, D. Zhang, and T. Murata (1990). However, the methodology for analyzing the self-stability of fault-tolerant clock synchronisation (FCS) systems introduced in that paper is applicable for FCS systems with many clocking modules, even if the combinatorial approach is not valid. This is due to the progress in improving the efficiency of the DSPN solution algorithm made in recent years. We show that the explicit computation of the steady-state solution of the DSPN can be performed with reasonable computational effort on a modern workstation by the software package DSPNexpress.< >
The microservices architectural style has been increasingly adopted in recent years due to its advantageous characteristics. While there exist design patterns for microservices that are theoretically beneficial for en...
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The microservices architectural style has been increasingly adopted in recent years due to its advantageous characteristics. While there exist design patterns for microservices that are theoretically beneficial for ensuring performance (and anti-patterns that should be avoided), they do not always lead to the expected impact. Some designs are solutions for achieving quality properties other than performance, and while they might be categorized as anti-patterns in theory, their influence on system performance can be minimal, depending on the context. Architects find it hard to reason about these trade-offs and the impact that design decisions will have on performance before implementing them. To solve this problem, in this paper, we propose an approach that enables rapid evaluation of high-level architectural models by combining both static and dynamic analysis. The static analysis identifies the design anti-patterns that are known to hinder system performance and guides the architect in reasoning about these design decisions. The approach then generates source code for the system under study based on the architectural design model for a subsequent dynamic analysis to assess whether the statically detected anti-patterns do indeed have a negative effect on the performance of the analyzed system.
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