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Asynchronous interface between a finite element commercial software ABAQUS and an academic research code HEREZH plus

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ADVANCES IN ENGINEERING SOFTWARE 2008年第12期39卷 1010-1022页

作者： Rio, G. Laurent, H. Bles, G. Univ Bretagne Sud Lab Genie Mecan & Mat F-56321 Lorient France ENSIETA Lab Mecan Struct Navales F-29806 Brest 09 France

The aim of this paper is to describe an efficient method to connect two independent softwares so as to jointly use best qualities of each software around a complex problem solved by the finite element emethod (FEM). This connection makes it possible to extend quickly and easily the applicability of new models developed in academic softwares, by their simultaneous use with commercial softwares. This is particularly interesting when these models are vey difficult to implement directly in commercial softwares. Most of the commercial FEM applications allow users to add additional features, physical models or boundary conditions via a programing interface. Within these user routines, access to internal data structures is possible, either through subroutine parameters and global variables, or via internal modules for reading and storing data. We use these capabilities to link the commercial software ABAQUS and an academic object-oriented C++ software HEREZH++, via the user-defined mechanical material behaviour (Umat). In this interface, HEREZH++ computes the mechanical behaviour of material and the code coupling performs a communication procedure between ABAQUS and HEREZH++. This paper describes this architecture which allows to implement easily original behaviour law and an interface written in c/C++. Several test samples are presented to show the efficiency and accuracy of the proposed implementations concernning the computational time. In particular, an industrial test is carried out with an original behaviour model of clasto-viscohysteresis which would have been very difficult to implement directly in ABAQUS. (c) 2008 Elsevier Ltd. All rights reserved.

关键词： code coupling interprocess communication ABAQUS HEREZH plus Umat object-oriented programming finite element analysis

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Precise time integration for linear two-point boundary value problems

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APPLIED MATHEMATICS AND COMPUTATION 2006年第1期175卷 182-211页

作者： Chen, Biaosong Tong, Liyong Gu, Yuanxian Dalian Univ Technol State Key Lab Struct Anal Ind Equipment Dept Engn Mech Dalian 116024 Peoples R China Univ Sydney Sch Aerosp Mech & Mechatron Engn Sydney NSW 2006 Australia

The precise time integration (PTI) method is proposed to solve the linear two-point boundary value problem (TPBVP). By employing the method of dimensional expanding, the non-homogeneous ordinary differential equations (ODEs) can be transformed into homogeneous ones and then the original PTI algorithms can be applied directly to the TPBVP. The PTI consists of two methods: the method of matrix exponential and the method of Riccati equations, both of which utilize the merit of 2(N) algorithm and guarantee high precise numerical results. The method of matrix exponential follows the similar scheme proposed for initial value problem of ODEs, and uses the matrix exponential to link boundary conditions between the two points. The method of Riccati equations employs the Riccati equations to express the relationships of two point boundary conditions. And then in terms of the relationships of boundary conditions at two points, the full conditions at initial point can be obtained and then the TPBVP can be transformed into initial value problem and then solved by direct time marching scheme. With some modifications, the. above algorithms can be directly extended to the infinite-interval problem and the variant coefficient ODEs problem. In the program implementation, the object-oriented (OO) design of PTI is proposed to demonstrate the applicability and easy maintenance of OO techniques in numerical computation. Finally, four selected numerical examples are given to show the high precision characteristics of PTI. (c) 2005 Elsevier Inc. All rights reserved.

关键词： precise time integration Riccati equations two point boundary value problem matrix exponential object-oriented programming

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An object-oriented constraints-based system for concurrent product development

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ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING 1999年第2期15卷 133-144页

作者： Gayretli, A Abdalla, HS De Montfort Univ Fac Comp Sci & Engn Dept Mech & Mfg Engn Leicester LE1 9BH Leics England

This research work aims to develop an intelligent constraint-based system that enables designers to consider at the early stages of the design process all activities associated with product's life cycle. One of the most important aspects of these activities is the evaluation and optimisation of manufacturing processes that require various type of information from the different aspects of product's life cycle. This research article discusses the development of a prototype system for manufacturing process optimisation using a combination of both mathematical methods and constraint-programming techniques. This approach enables designers to evaluate and optimise feasible manufacturing professes in a consistent manner as early as possible during the design process. This helps in avoiding unexpected design iterations that wastage a great amount of time and effort, leading to longer lead-time. The development process has passed through the five major stages: Firstly, an intelligent constraint-based design system for concurrent product and process design has been developed. Secondly, a manufacturing process optimisation module has been constructed. Thirdly, the product features, processes, cost, time and constraints to be used for carrying out various design tasks has been represented in the format of constraints, frames, objects, and rules. Fourthly, the process optimisation and evaluation rules for the selection of feasible processes for complex features, and finally, the information management system that ensures consistency in information exchange and decision making activities have been developed. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.

关键词： feature-based design object-oriented programming concurrent engineering process optimisation cost estimation constraints knowledge-based systems

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Modeling of concentrated aqueous solutions: Efficient implementation of Pitzer equations in geochemical and reactive transport models

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COMPUTERS & GEOSCIENCES 2010年第4期36卷 526-538页

作者： Bea, S. A. Carrera, J. Ayora, C. Baffle, F. CSIC Inst Environm Assessment & Water Res IDAEA GHS E-08028 Barcelona Spain

Modeling concentrated solutions demands the use of ion-interaction models such as Pitzer equations, which involve a large number of operations. Implementation of these models in large reactive transport simulations significantly increases the computation time with respect to traditional activity coefficient models. CPU time depends on the efficiency of (1) the Pitzer algorithm itself, and (2) the speciation algorithm. We present an implementation of the Pitzer model that improves traditional implementations by using a compact matrix approach. This facilitates programming and computation of derivatives. The use of analytic derivatives allows the use of Newton-Raphson algorithms, which converge quickly. The approach is implemented in an object-oriented programming (OOP) scheme by creating an entity that represents the thermodynamic behavior of both dilute and concentrated solutions. This entity is readily linked to any geochemical or reactive transport codes. We show that the code is robust, in that its implementation improves the convergence in a broad range of geochemical calculations, and efficient, in that its CPU time compares favorably with other codes. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Pitzer HMW model Geochemical modeling Concentrated solutions Reactive transport modeling object-oriented programming Invariant points Evaporation of seawater

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KNOWLEDGE-BASED CASE TOOLS - IMPROVING PERFORMANCE USING DOMAIN-SPECIFIC KNOWLEDGE

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SOFTWARE ENGINEERING JOURNAL 1994年第4期9卷 167-173页

作者： LLOYDWILLIAMS, M UNIV SHEFFIELD DEPT INFORMAT STUDIESSHEFFIELD S10 2TNS YORKSHIREENGLAND

Knowledge-based CASE tools are able to play an active part in the design of computer-based systems. Providing such tools with in-built domain-specific (or 'real world') knowledge can enhance both the performance and the appearance of intelligence. However, little work has so far been carried out as to how this might be achieved. The paper illustrates how such knowledge may be provided in the form of generic models based on a thesaurus approach, and applies the technique to a knowledge-based CASE tool designed to support object-oriented design.

关键词： object-oriented design software tools generic models Expert systems and other AI software and techniques programming support intelligent design assistants object-oriented programming domain-specific knowledge thesaurus approach computer-based systems knowledge-based CASE tools knowledge representation object-oriented programming

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Node-based dynamic adaptive grid with quadrilateral and hexahedral elements

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ADVANCES IN ENGINEERING SOFTWARE 1999年第1期30卷 31-41页

作者： Wang, GH Tyler, JM Weltman, JS Callahan, JD Geoquest Unit Schlumberger Houston TX 77056 USA Louisiana State Univ Dept Comp Sci Baton Rouge LA 70803 USA Innovat Emergency Management Baton Rouge LA 70809 USA InControl Technol Houston TX 77068 USA

A node-based data structure is developed for use in either two-dimensional (2-D) or three-dimensional (3-D) finite element method (FEM) problems. This grid uses quadrilateral (2-D) or hexahedral (3-D) elements and is dynamically adaptive according to the 1-irregular requirement for refinement-derefinement. Implemented in C + +,the grid consists of node objects linked with pointers to neighboring node objects. The algorithm used to traverse the grid starts at the first node of the grid and constructs each FEM element by following the links of the nodes. This algorithm uses a stack to maintain the correct order of elements during the grid traversals. Because the elements and their connectivity are not permanently stored, the computer storage requirements for the grid are reduced significantly in 3-D compared with an element-based approach. Although the node-based approach may increase the CPU-time and complexity to access an element, it reduces the complexity and time required to refine and derefine an element. This implementation is applicable to many FEM domains. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

关键词： dynamic adaptive mesh adaptive finite elements nodal-based data structures object-oriented programming C++ FORTRAN

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SEED-Config: a tool for conceptual structural design in a collaborative building design environment

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ARTIFICIAL INTELLIGENCE IN ENGINEERING 2000年第3期14卷 233-247页

作者： Fenves, SJ Rivard, H Gomez, N Concordia Univ Ctr Bldg Studies Dept Bldg Civil & Environm Engn Montreal PQ H3G 1M8 Canada NIST Gaithersburg MD 20899 USA Florida Int Univ Dept Civil & Environm Engn Miami FL 33199 USA

SEED-Config is a design environment intended to assist structural designers in collaboratively exploring and extending the design buildings. Its purpose is to help designers in rapidly synthesizing alternative structural design solutions at the conceptual level to the point where the structural concept is supportive of the overall design and possible conflicts are explored and resolved. The SEED-Config prototype consists of four subsystems. The Design Information Repository is built upon an information model that exploits the hierarchical nature of building descriptions to represent design information. It can save an overall design or parts of a design to a case library, thus supporting case-based reasoning. The Design Knowledge Manager allows for the browsing, editing, selecting and applying of technology nodes which encapsulate structural design knowledge. The Classification Reference Manager allows for the definition, management, inference and querying of classifications which are used to classify and index design solutions as they are generated. The Geometric Modeler reasons about topology and geometry. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： design environment conceptual design building design structural design collaborative design case-based reasoning information model knowledge representation classification and indexing object-oriented programming

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Minimum cost wavelength-path routing and wavelength allocation using a genetic-algorithm heuristic hybrid approach

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IEE PROCEEDINGS-COMMUNICATIONS 1999年第1期146卷 1-7页

作者： Sinclair, MC Univ Essex Dept Elect Syst Engn Colchester CO4 3SQ Essex England

Minimum cost wavelength-path routing and wavelength allocation of multiwavelength alloptical transport networks using a genetic-algorithm (GA)/heuristic hybrid approach is described. A cost model is adopted which incorporates a dependency on link wavelength requirements. The hybrid algorithm developed uses an object-oriented representation of networks, and incorporates four operators: path mutation, single-point crossover, reroute and shift-out. In addition, an operator-probability adaptation mechanism is employed to improve operator productivity. Experimental results from seven fifteen-node test networks, obtained using a tool for optical network optimisation, modelling and design (NOMaD), suggest the GA/heuristic hybrid approach provides superior results compared to three recent wavelength-allocation heuristics, except when the network cost depends most heavily on wavelength requirement.

关键词： Optimisation techniques GA/heuristic hybrid approach genetic-algorithm/heuristic hybrid approach genetic algorithms multiwavelength all-optical transport networks fifteen-node test networks cost model link wavelength requirements network cost object-oriented methods optical network optimisation modelling and design single-point crossover object-oriented representation wavelength allocation NOMaD Communication network design, planning and routing Optical fibre networks operator productivity frequency allocation object-oriented programming telecommunication network routing operator-probability adaptation mechanism minimum cost wavelength-path routing optical fibre networks shift-out path mutation reroute

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A COMPUTER-AIDED AIRCRAFT FRAME ASSEMBLY PLANNER

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COMPUTERS IN INDUSTRY 1995年第3期27卷 259-271页

作者： LIAO, TW WU, XW ZHENG, SQ LI, SQ NANCHANG AIRCRAFT MFG CO NANCHANGPEOPLES R CHINA LOUISIANA STATE UNIV DEPT COMP SCIBATON ROUGELA 70803 MEM SLOAN KETTERING CANC CTR NEW YORKNY 10021

This paper presents a computer-aided planning system that is capable of generating assembly sequences for aircraft frame assemblies. The representation scheme for aircraft frame assemblies is first described. Algorithms for the automated generation of assembly sequences are then discussed. The planning system takes assembly drawing and bill of material as inputs. In consideration of both the geometric and technical constraints in the planning stage, the system generates an assembly sequence as output. The system has been implemented using an object-oriented approach (C++) and a graphical user interface under MS-Windows. A spar subassembly is used to demonstrate the working of the methodology as well as the implemented system.

关键词： COMPUTER-AIDED ASSEMBLY PLANNING AIRCRAFT FRAME ASSEMBLY ASSEMBLY SEQUENCE GENERATION object-oriented programming

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Dynamic aspect mining

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IET SOFTWARE 2009年第4期3卷 321-336页

作者： Ceccato, M. Tonella, P. Fdn Bruno Kessler Trento Italy

Legacy systems often contain several crosscutting concerns that could potentially benefit from an aspect-oriented programming implementation. In this paper, we focus on the problem of aspect identification in existing code. The main idea is that use-cases can be defined in order to separate the base logics from the crosscutting concerns to be aspectised. The relationship between the execution traces associated with the use-cases and the executed computational units (class methods) is analysed through concept analysis. The results obtained on some case studies are discussed in the paper.

关键词： data mining executed computational unit aspect-oriented programming Software engineering techniques aspect identification Knowledge engineering techniques dynamic aspect mining software engineering object-oriented programming legacy systems software development object-oriented programming

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