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Tsinghua Science and Technology

Issue 2 • Date June 1999

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Displaying Results 1 - 23 of 23
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • Contents

    Page(s): 1 - 2
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    Freely Available from IEEE
  • Concurrent engineering research and application

    Page(s): 1375 - 1385
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    Research and application of Concurrent Engineering have produced good results. A Chine se style concurrent engineering architecture and reference mode has been produced. A series of break thoughts in BPR (Business Process Reengineering) have been made with organization of the IPT (Integrated Product Development Team) and engineering support technologies. Several prototype tools were developed, including product development process modeling and management, QFD-based schema design and decision making, PDM-based concurrent design, STEP-based CAD/CAPP/CAM integration, design for assembly, design for manufacturing, computer aided fixture design, and machining process simulation. Finally, the research results were used in the devlopment of two complex components in an aerospace application, and satisfactory results were obtained. View full abstract»

    Open Access
  • Product development process modeling

    Page(s): 1386 - 1391
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    The use of Concurrent Engineering and other modern methods of product development and maintenance require that a large number of time-overlapped "processes" be performed by many people. However, successfully describing and optimizing these processes are becoming even more difficult to achieve. The perspective of industrial process theory (the definition of process) and the perspective of process implementation (process transition; accumulation, and inter-operations between processes) are used to survey the method used to build one base mode(multi-view) process model, View full abstract»

    Open Access
  • Consistent algorithm for multi-value constraint with continuous variables

    Page(s): 1392 - 1396
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    Mature algorithms for the Constraint Satisfaction Problem (CSP) of binary constraint with discrete variables have already been obtained for the application. For the instance of multi value constraint with continuous variables, the approach will be quite different and the difficulty of settling will aggrandize a lot. This paper presents the algorithm for realizing global consistency of continuous variable. And this algorithm can be applied to multi value constraint. View full abstract»

    Open Access
  • Case based reasoning in conflict negotiation in concurrent engineering

    Page(s): 1397 - 1402
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    Case-based reasoning (CBR) is a kind of analogous reasoning that is widely used in artificial intelligence. Conflicts are pervasive in Concurrent Engineering design environment. Conflict negotiation is necessary when conflicts occur. It is difficult to resolve conflicts due to several reasons. An approach to resolving conflicts by case-based reasoning is proposed in this paper. The knowledge representation of conflict negotiation cases, the judgment of case similarity, the retrieval model of cases, the management of case bases, and the process of case-based conflict negotiation are studied. The implementation structure of the Case based Conflict Solving System (CCSS) is also given. View full abstract»

    Open Access
  • Feature analysis of STEP application protocol and its application

    Page(s): 1403 - 1406
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    This paper uses semantic data modelling and CAD/CAPP/CAM integration to analyze the features defined in the STEP AP214, its characteristics of definition and distribution, and its influence on the complexity of CAD/CAPP/CAM application integration. A framework is developed for applications of CAD/CAPP/CAM integration based on the STEP to reduce the complexity of integration implementation. Two application program interfaces (API), namely, application protocol API and application API, are developed. The framework's hierarchy structure and the application program interfaces between the layers make the integration of applications easier. View full abstract»

    Open Access
  • Multimedia conferencing system and multicasting

    Page(s): 1407 - 1411
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    The multimedia conferencing system is an important tool for Computer supported Cooperative Work (CSCW), and also one of the basic techniques supporting team work in the Concurrent Engineering. In this paper the architecture and function modules of the reported multimedi a conferencing system are described. Then in order to reduce the network bandwidth required by the conferencing system, two methods for sending the conferencing data by using multicasting are discussed. View full abstract»

    Open Access
  • Concurrent engineering oriented CAx/DFx information integration

    Page(s): 1412 - 1417
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    The information integration, especially in CAD/CAPP/CAM, is a basis for realizing the integrated and concurrent product development in Concurrent Engineering (CE) environment. The integration technology based on STEP application protocol gives an effective way for the CAx/DFx information integration. This paper discusses the characteristics of concurrent product development, analyzes the methodology and technology of STEP, proposes an information integration approach based on STEP AP214, and presents the strategy of product data integration and an integration system implementation architecture. The integration technology based on STEP application protocol and the ST-Developer tools is realized in a prototype system to support product data integration between CAD and its follow up systems through STEP physical file and STEP information exchange interface. View full abstract»

    Open Access
  • DFM/CAPP/CAM system in a concurrent engineering environment

    Page(s): 1418 - 1423
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    In this paper the importance of DFM/CAPP/CAM system in Concurrent Engineering (CE) is discussed. Based on the analyses of the character of concurrent product design and manufacturing process design, the workflow of DFM/CAPP/CAM system in CE is given. DFM/CAPP/CAM theories, methods and functions are invesigated in a delicate and all-round way, and are implemented in the developed DFM/CAPP/CAM system View full abstract»

    Open Access
  • CAPP framework system for concurrent engineering

    Page(s): 1424 - 1430
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    Difficulty in generalizing and lack of adaptability are important factors that hamper a computer aided process planning (CAPP) system from being popular and practical. New manufacturing philosophies such as Concurrent Engineering require special characteristic of a CAPP system. Proposed in this paper is a CAPP framework system for Concurrent Engineering (CAPPFS-CE) which can meet the requirements of Concurrent Engineering and whose information models, function models and decision logic can be customized by users to form various CAPP applicati on systems. Its function requirements are discussed broadly. An architecture for CAPPFS CE is presented. It is based on abstract information models (AIMs) and abstract function models (AFMs). The kernel is formed by customization interpretation, internal process control and decision engine. A new information modeling and system development method, information element method (IEM), is introduced to build up AIMs, decision engine, and AFMs and then realize a CAPPFS CE THCAPP-SHELL, a CAPPFS-CE developed by IEM, is demonstrated. A CAPP system produced by customizing THCAPP SHELL for complex structural parts in a concurrent engineering environment is shown View full abstract»

    Open Access
  • Numerical simulation system for casting process in concurrent engineering

    Page(s): 1431 - 1435
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    According to the implementing principle and application background of the Concurrent Engineering (CE) project, studies on the integration of numerical simulation system for casting process with CE, simulation of turbulent phenomena in filling process of casting by Algebraic Stress Model (ASM), computation efficiency of filling process and quantitative prediction of shrinkage cavity and porosity under feeding condition of several risers are discussed. After the simulation of casting process of typical magnesium based alloy casting with complicated structure, remarkable success in assuring the quality is also presented. View full abstract»

    Open Access
  • Assembly sequence planning for mechanical products

    Page(s): 1436 - 1439
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    A method for assembly sequence planning is proposed in this paper. First, two methods for assembly sequence planning are compared, which are indirect method and direct method. Then, the limits of the previous assembly planning system are pointed out. On the basis of indirect method, an improved method for assembly sequence planning is put forward. This method is composed of four parts, which are assembly modeling for products, assembly sequence representing, assembly sequence planning, and evaluation and optimization. The assembly model is established by human machine interaction, and the assembly model contains components' infomration and the assembly relation among the components. The assembly sequence planning is based on the breaking up of the assembly model. And/or graph is used to represent assembly sequence set. Every component which satisfies the disassembly condition is recorded as a node of an and/or graph. After the disassembly sequence and/or graph is generated, heuristic algorithm — AO algorithm is used to search the disassembly sequence and/ or graph, and the optimum assembly sequence planning is realized. This method is proved to be effective in a prototype system which is a sub project of a state 863/CIMS research project of China — ‘Concurrent Engineering’. View full abstract»

    Open Access
  • Part machinability evaluation system

    Page(s): 1440 - 1442
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (557 KB)  

    In the early design period, estimation of the part or the whole product machinability is useful to consider the function and process request of the product at the same time so as to globally optimize the design decision. This paper presents a part machinability evaluati on system, discusses the general restrictions of part machinability, and realizes the inspection of these restrictions with the relation between tool scan space and part model. During the system development, the expansibility and understandability were considered, and an independent restriction algorithm library and a general function library were set up. Additionally, the system has an interpreter and a knowledge manager. View full abstract»

    Open Access
  • Automatlc fixture planning

    Page(s): 1443 - 1447
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    Fixture planning is a, crucial problem in the field of fixture design. In this paper, the research scope and research methods of the computer-aided fixture planning are presented. Based on positioning principles of typical workparts, an ANN algorithm, namely Hopfield algorithm, is adopted for the antomatic fixture planning. Also, this paper leads a deep research into the selection of positioning and clamping surfaces (or points) on workparts using positioning-clamping-surface-selecting rule and matrix evaluation of deterministic worlpart positioning. In the end of this paper, the methods to select positioning and clamping elements from database and the layout algorithm to assemble the selected fixture elements into a tangible fixture are developed. View full abstract»

    Open Access
  • Study and application of cooperative work environment

    Page(s): 1448 - 1450
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    The concept of Cooperative Work Environment (CWE) is introduced. Three key elements of CWE, inforrration integration, process integration, and organization integration, are analysed. An application framework of CWE is prcoosed and with this framework a CE CWE based on Lotus Notes/Domino and Intel Proshare used in a large enterprise is introduced. View full abstract»

    Open Access
  • Affinity capillary electrophoresis: Study of the binding of HIV-1 gp 41 with a membrane protein (P45) on the human B cell line, Raji

    Page(s): 1454 - 1457
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    Affinity capillary electrophoresis has been used to study the interaction between a membrane protein (P45) isolated from the Human B cell line, Raji, and rsgp 41. P45, rsgp 41 and the complexes were well resolved. The entire separation was achieved in less than 3 min. Formations of two kinds of stable P45-rsgp 41 complexes were confirmed based on migration time comparison; the binding equilibrium was achieved as soon as two proteins were mixed. The results indicate that the interaction between P45 and rsgp 41 is strong with a fast association rate and a slow dissoction rate, and there are at least two kinds of binding sites with different binding constants between P45 and rsgp 41. View full abstract»

    Open Access
  • Electronic states of some semiconductor clusters

    Page(s): 1458 - 1461
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    Potential surfaces and equilibrium geometries of InAs2, In2As, InAs2+ and In2As+ were studied using the complete active space multi-configuration self consistent field (CASMCSCF) technique. Two electronic states, namely 2B2 and 2B1 were fround to prevail as the ground states for the InAs2 and In2As trimers, respectively. The corresponding adiabaticionzation energies were computed and the leading configurations of the ground states were analyzed according to the wavefunctions. View full abstract»

    Open Access
  • Determination and prediction of binary solubility for aromatic-tetraethylene glycol (with water) systems

    Page(s): 1462 - 1465
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    The binary solubilities of tetraethylene glycol (TTEG) with benzene, toluene or p-xylene, were measured by the turbidity point method. In TTEG the content of water ranged from 0 to 5% and the test temperature ranged from 20°C to 120°C. Increasing the temperature resulted in greater solubility of the aromatics in TTEG, while increasing the content of water caused the aromatic solubility to decrease. The benzene solubillity in TTEG was the greatest followed by toluene and xylene at the same water content and temperature. The mutual solubility was predicted by correlating the paramaters of a new group for the UNIFAC model for the arorratics extraction system The modified UNIFAC group contributi on model was used to predict the binary solubility of TTEG and arorratics The average deviation between the experimental result and prediction is 4.06% Therefore, the UNIFAC model can be used to describe the solubility phenomena for TTEG aromatics systerrs. View full abstract»

    Open Access
  • Filtration process of the spiramycin fermentation broth

    Page(s): 466 - 1471
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    This paper presents the effects Of acidity and additive pretreatment on the filtering rate and Spirarnycin (SPM) concentration in the filter liquor of SPM fermentation broth. The experimental results show that the SPM peak value in filter liquor iS obtained at pH5.5 with either 0.1% methanal or 0.1% BAPE. It is also indircatedt that there exists a dissolution equilibrium of proteins from the experiment results. The soluble proteins are denatured due to the too high/low acidity and then precipitate. Usually, the amount of soluble proteins reaches its lowest leve1 in pH range of 6.0–6.5. The protein precipitation will, together with other suspended solids, particles, contribute to the final SPM concentration in the filter liquor. This paper assumes that the contribution is the result of the adsorption equilibrium of SPM on the surfaces of suspened solids. For satisfactory explanation, the revised Landgmuir adsorption theory was employed and a model was developed. View full abstract»

    Open Access
  • Overexpressions of lambda phage lysis genes and biosynthetic genes of poly-β-hydroxybutyrate in recombinant E. coli

    Page(s): 1472 - 1476
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    A plasmid (pTu9) containing the lambda (λ) phage lysis genes S(−) RRz and the biosynthetic genes phb CAB of poly-β-hydroxybutyrate (PHB) was constructed and transformed into E. coli JM109. Oultured in Luria Bertani (LB) medium with 20g/Lglucose, E. coli JM109 (pTu9) could accumulate PHB in cells up to 40% (g PHB per g dry cells). Achelating agent EDTA was applied to induce a corrplete cell lysis and PHB granules were released. This method has a potential application in PHB separation. View full abstract»

    Open Access
  • Extractive distillation with salt in solvent

    Page(s): 1477 - 1479
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    Extractive distillation with salt in solvent is a new process for producing anhydrous ethand by combining the principle of “salt effecf” and some traditional extractive distillation methods. Compared with the common extractive distillation the performance of solvent is improved, the recycling amount of slovent is reduced to 1/4–1/5, and the number of theoretical plates is reduced to 1/3 Energy conamption and cost of equipment are also reduced and continuous production is realized. High efficiency and low solvent wastage rrake this technique feasible. View full abstract»

    Open Access
  • Synthesis of ultrafine AlN powders in an Al-OC-N system

    Page(s): 1480 - 1484
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    AlN powders were Synthesized by both ordinary and modified processes of carbothermal reduction and nitridation in an Al-OC-N system. In the ordinary process, the AlN phase appeared at 1300°C for 6h and the nitridation was completed at 1600°C for 6h. The particle size of the ordinary AlN powders was about 1μm and the specific sarface area was 1–1.5 M2/g. In the modified process, the nitridation began and was completed at a terrperature lower than that for the ordinary process by more than 100K. The particle size was much finer, 0.1–0.21μm, and the specific surface area was about 20m2/g. At some conditions, the AlN whiskers appeared in the powders. The nitridation rate was a function of the temperature and N2 flow rate as well as the reaction period. The results are used to discuss some aspects of the mechanism. View full abstract»

    Open Access

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Tsinghua Science and Technology (Tsinghua Sci Technol) aims to highlight scientific achievements in computer science, electronic engineering, and other IT fields. Contributions all over the world are welcome.

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