In this paper, we describe the design and development of a simulation-agent interface for real-time distributed control system benchmarking. This work is motivated by the need to test the feasibility of extending agen...
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In this paper, we describe the design and development of a simulation-agent interface for real-time distributed control system benchmarking. This work is motivated by the need to test the feasibility of extending agent-based systems to the physical device level in manufacturing and other industrial automation systems. Our work focuses on the development of hybrid physical/simulation environment that can be used to perform tests at both the physical device level, as well as the planning and scheduling level of control. As part of this work, we have extended the proxy design pattern for this application. This paper focuses on the resulting software design pattern for distributed control system benchmarking and provides examples of its use in our hybrid physical/simulation environment. (c) 2007 Elsevier Ltd. All rights reserved.
We present an object-oriented modeling frame for simulating crack propagation due to cyclic loadings. Central to the approach is that the crack propagates when a user-defined propagation criterion is fulfilled, i.e., ...
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We present an object-oriented modeling frame for simulating crack propagation due to cyclic loadings. Central to the approach is that the crack propagates when a user-defined propagation criterion is fulfilled, i.e., the crack propagation rate is not prescribed but predicted. The approach utilizes the commercial finite element software package ABAQUS and its associated Python based scripting interface. The crack propagation is simulated by a generalized node release technique. If the propagation criteria are satisfied in the end of a cycle, the crack is allowed to propagate. The incremental crack growth is inferred from an iterative investigation of the propagation criteria. The propagation criteria are user-defined, and can be based on any parameter or parameter set that can be obtained from the simulations. We illustrate the developed modeling frame by two benchmark problems, where the propagation criterion is based on the dissipated energy in the vicinity of the crack tip. (c) 2008 Elsevier Ltd. All rights reserved.
In this paper we present a new one-dimensional full electromagnetic relativistic hybrid plasma model. The full kinetic particle-in-cell (PIC) and hydrodynamic model have been combined in the single hybrid plasma code ...
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In this paper we present a new one-dimensional full electromagnetic relativistic hybrid plasma model. The full kinetic particle-in-cell (PIC) and hydrodynamic model have been combined in the single hybrid plasma code H-VLPL (hybrid virtual laser plasma laboratory). The semi-implicit algorithm allows to simulate plasmas of arbitrary densities via automatic reduction of the highest plasma frequencies down to the numerically stable range. At the same time, the model keeps the correct spatial scales like the plasma skin depth. We discuss the numerically efficient implementation of this model. Further, we carefully test the hybrid model validity by applying it to a series of physical examples. The new mathematical method allows to overcome the typical time step restrictions of explicit PIC codes. (C) 2008 Elsevier B.V. All rights reserved.
Despite the fact that there has been a wide adoption of unified modelling language activity diagrams (UML ADs) for software development, research focusing on the equivalence notions of UML ADs is scarce. To address th...
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Despite the fact that there has been a wide adoption of unified modelling language activity diagrams (UML ADs) for software development, research focusing on the equivalence notions of UML ADs is scarce. To address this area of concern, the author presents a sound theoretical foundation for UML ADs. Through the use of these formal definitions of UML ADs, the author propounds a method which classifies various types of equivalences of UML ADs in a systematic way. The proposed classification, which is the core result of our work, provides a framework that enables the study of the properties and inter-relationships of the equivalences.
We outline an approach for extending procedural finite-element software components using generic programming. A layer of generic software components consisting of C++ containers and algorithms is used for parallelizat...
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We outline an approach for extending procedural finite-element software components using generic programming. A layer of generic software components consisting of C++ containers and algorithms is used for parallelization of the finite-element solver and for solver coupling in multi-physics applications. The advantages of generic programming in connection with finite-element codes are discussed and compared with those of object-oriented programming. The use of the proposed generic programming techniques is demonstrated in a tutorial fashion through basic illustrative examples as well as code excerpts from a large-scale finite-element program for serial and parallel computing platforms.
This article describes the experience and results obtained teaching non-common lava features, in advanced undergraduate object-oriented programming courses. The teaching approach proposed helps students to reach a dee...
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This article describes the experience and results obtained teaching non-common lava features, in advanced undergraduate object-oriented programming courses. The teaching approach proposed helps students to reach a deeper level of programming expertise, while accomplishing specific assignments that integrate a class framework that supports implementation of medium size client-server applications. (C)2008 Wiley Periodicals. Inc. Comput Appl Eng Educ 16: 305-314, 2008: Published online in Wiley InterScience (***): DOI 10.1002/cae.20127
Aspect mining tries to identify crosscutting concerns in the code of existing systems and thus supports their adaption to an aspect-oriented design. A semi-automatic static aspect mining approach is described, where c...
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Aspect mining tries to identify crosscutting concerns in the code of existing systems and thus supports their adaption to an aspect-oriented design. A semi-automatic static aspect mining approach is described, where constraints,such as the requirement that the patterns have to exist in different calling contexts. Two case studies done with the implemented tool show that many discovered candidates for crosscutting concerns are instances of delegation and should not be refactored into aspects. More generally, it is shown that aspect mining techniques need a way to distinguish between delegation and superimposed behaviour.
This paper presents the results of an investigation into the various ways in which pre-service and in-service teachers experience learning to program in an object-oriented language. Both groups of teachers were enroll...
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This paper presents the results of an investigation into the various ways in which pre-service and in-service teachers experience learning to program in an object-oriented language. Both groups of teachers were enrolled in university courses. In most cases, the pre-service teachers were learning to program for the first time, while the in-service teachers had previously programmed using a procedural programming language. Phenomenography was used to identify categories of description of learning to program. From these categories an outcome space was created that shows the relationship between different experiences of learning to program. The outcome space can be represented as circles inscribed within one another, where the innermost circle represents a lower level of cognitive accomplishment and the outer circles subsume the inner circles. The five levels of the outcome space are: meeting the requirements, learning the syntax/learning by comparison, understanding and assimilating, problem solving and programming in the large. Implications of the findings for teaching are discussed. (c) 2007 Elsevier Ltd. All rights reserved.
In this paper, we describe O-DEVICE, a memory-based knowledge-based system for reasoning and querying OWL ontologies by implementing RDF/OWL entailments in the form of production rules in order to apply the formal sem...
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In this paper, we describe O-DEVICE, a memory-based knowledge-based system for reasoning and querying OWL ontologies by implementing RDF/OWL entailments in the form of production rules in order to apply the formal semantics of the language. Our approach is based on a transformation procedure of OWL ontologies into an object-oriented schema and the application of inference production rules over the generated objects in order to implement the various semantics of OWL. In order to enhance the performance of the system, we introduce a dynamic approach of generating production rules for ABOX reasoning and an incremental approach of loading ontologies. O-DEVICE is built over the CLIPS production rule system, using the object-oriented language COOL to model and handle ontology concepts and RDF resources. One of the contributions of our work is that we enable a well-known and efficient production rule system to handle OWL ontologies. We argue that although native OWL rule reasoners may process ontology information faster, they lack some of the key features that rule systems offer, such as the efficient manipulation of the information through complex rule programs. We present a comparison of our system with other OWL reasoners, showing that O-DEVICE can constitute a practical rule environment for ontology manipulation.
Seismic isolation can significantly reduce the induced seismic loads to a relatively stiff building by inserting flexibility at its base to avoid resonance with the predominant frequencies of common earthquakes. Somet...
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Seismic isolation can significantly reduce the induced seismic loads to a relatively stiff building by inserting flexibility at its base to avoid resonance with the predominant frequencies of common earthquakes. Sometimes the width of the provided seismic gap to facilitate the large relative displacements at the isolation level of a seismically isolated building is limited. Hence, there is a possibility of poundings of the building with adjacent structures during strong earthquakes. This work investigates, through numerical simulations using a specially developed software, how potential poundings of seismically isolated buildings with adjacent structures affects the effectiveness of seismic isolation. (C) 2007 Elsevier Ltd. All rights reserved.
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