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Novel Models and Algorithms of Load Balancing for Variable-structured Collaborative Simulation under HLA/RTI

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Chinese Journal of Mechanical engineering 2013年第4期26卷 629-640页

作者： YUE Yingchao FAN Wenhui XIAO Tianyuan MA Cheng state cims engineering research center Tsinghua University

High level architecture(HLA) is the open standard in the collaborative simulation field. Scholars have been paying close attention to theoretical research on and engineering applications of collaborative simulation based on HLA/RTI, which extends HLA in various aspects like functionality and efficiency. However, related study on the load balancing problem of HLA collaborative simulation is insufficient. Without load balancing, collaborative simulation under HLA/RTI may encounter performance reduction or even fatal errors. In this paper, load balancing is further divided into static problems and dynamic problems. A multi-objective model is established and the randomness of model parameters is taken into consideration for static load balancing, which makes the model more credible. The Monte Carlo based optimization algorithm(MCOA) is excogitated to gain static load balance. For dynamic load balancing, a new type of dynamic load balancing problem is put forward with regards to the variable-structured collaborative simulation under HLA/RTI. In order to minimize the influence against the running collaborative simulation, the ordinal optimization based algorithm(OOA) is devised to shorten the optimization time. Furthermore, the two algorithms are adopted in simulation experiments of different scenarios, which demonstrate their effectiveness and efficiency. An engineering experiment about collaborative simulation under HLA/RTI of high speed electricity multiple units(EMU) is also conducted to indentify credibility of the proposed models and supportive utility of MCOA and OOA to practical engineering systems. The proposed research ensures compatibility of traditional HLA, enhances the ability for assigning simulation loads onto computing units both statically and dynamically, improves the performance of collaborative simulation system and makes full use of the hardware resources.

关键词： static load balancing dynamic load balancing variable-structure collaborative simulation under HLA/RTI multi-objective optimization ordinal optimization

Synergic Motion Trajectory Planning for Airplane Docking Based on6PURU Parallel Mechanism

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tsinghua Science and Technology 2015年第2期20卷 188-199页

作者： Hui Li Linxuan Zhang Tianyuan Xiao Jietao Dong state cims engineering research center at tsinghua university

Motion planning issues encountered in assembling airplanes by employing the 6PURU parallel mechanism are analyzed in this paper. A sine curve of the change rate of acceleration, which is called as jerk in the following text, is proposed for uniaxial flexible acceleration and deceleration planning based on the optimal time and velocity and acceleration constraints. Compared with other curves, the proposed curve can realize a continuous n-order derivative and the smooth change of the speed and acceleration. The method is computational^y simple and suitable for programming. In addition, a multiaxial coordinated movement scheme is proposed. The motion trajectory is no longer simply split into many single-direction trajectories nor are all single-direction planning trajectories combined directly. The multiaxial coordinated movement scheme aims to achieve synergic movement in multiple directions to ensure smoothness of the movement in the event of a kinematic error when maintaining a stable value. If the movement fails to achieve this goal, driving force mutations will deteriorate the effect of synergic movement. A physical model of the parallel mechanism is developed in simMechanics, and a holistic system model is completed in SIMULINK. The feasibility of the new planning algorithm is simulated and tested, and then, the multiaxial synergic movement planning method is proposed and verified.

关键词： assembly simulation motion trajectory planning parallel mechanism simMechanics

research ON PRODUCT INNOVATION DESIGN IN VIRTUAL PRODUCT DEVELOPMENT

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Chinese Journal of Mechanical engineering 2002年第4期15卷 353-359页

作者： Wu Qunbo Zhang Linxuan Xiao Tianyuan Long Xinghai state cims engineering research center, tsinghua university, Beijing 100084, China state cims engineering research center Tsinghua University Beijing 100084 China

An integrated template of virtual product development alters primarilysequential tradition mode of product life cycle. The template integrates all processes of productdevelopment using digital modem. An environment of virtual product development provides productdevelopment environment of integration, communion, network, concurrent and collaboration. Combiningdevelopment of new rapier loom, an innovated design process is researched in virtual productdevelopment, which consists three portions: constructing an integration development environment,innovation design and manufacturing simulation. The innovated design process realizes reversedesign, mechanism concept design, structural design and analysis, performance analysis andmanufacturing process simulation of virtual product, which can enhance greatly product performanceand reduce cost and development cycle of new product.

关键词： virtual product development innovation design product data management

GENERATION AND APPLICATION OF VARIATIONAL GEOMETRIC CONSTRAINTS NETWORK BASED ON ISO'S FEATURE

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Chinese Journal of Mechanical engineering 2002年第4期15卷 319-323页

作者： Hu Jiestate cims engineering research center, tsinghua university, Beijing 100084, ChinaWu Zhaotong Zhejiang university state cims engineering research center Tsinghua University Beijing 100084 China

The concept of variantional geometric constraints network is presented. Basedon ISO's feature, three kinds of variational geometric constraints are defined. The concepts ofmate tree (MT) and loop circuit (LC) are presented. The generation method of well-constrainedvariational geometric constraints network (VGCN) is studied. The network can be applied ingeneration of well-constrained tolerance types and tolerance chains. A simple example is analyzed toshow the scheme to be effective.

关键词： ISO's feature variational geometric constraint tolerance

Formal Verification of Temporal Properties for Reduced Overhead in Grid Scientific Workflows

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Journal of Computer Science & Technology 2011年第6期26卷 1017-1030页

作者：曹军威张帆许可刘连臣吴澄 CCF ACM IEEE research Institute of Information Technology Tsinghua University tsinghua National Laboratory for Information Science and Technology National cims engineering and research center Tsinghua University Morgan Stanley

With quick development of grid techniques and growing complexity of grid applications, it is becoming critical for reasoning temporal properties of grid workflows to probe potential pitfalls and errors, in order to ensure reliability and trustworthiness at the initial design phase. A state Pi calculus is proposed and implemented in this work, which not only enables fexible abstraction and management of historical grid verification of grid workflows. Furthermore, a relaxed region system events, but also facilitates modeling and temporal analysis （RRA） approach is proposed to decompose large scale grid workflows into sequentially composed regions with relaxation of parallel workflow branches, and corresponding verification strategies are also decomposed following modular verification principles. Performance evaluation results show that the RRA approach can dramatically reduce CPU time and memory usage of formal verification.

关键词： grid computing workflow management formal verification state Pi calculus

Data fusion and simulation-based planning and control in cyber physical system for digital assembly of aeroplane

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International Journal of Modeling, Simulation, and Scientific Computing 2015年第3期6卷 66-84页

作者： Hui Li Linxuan Zhang Tianyuan Xiao Jietao Dong state cims engineering research center at tsinghua university Main Building Room 604 Beijing 100084P.R.China state cims engineering research center at tsinghua university Main Building Room 601 Beijing 100084P.R.China state cims engineering research center at tsinghua university Main Building Room 619 Beijing 100084P.R.China

This paper introduces a CPS application for intelligent aeroplane *** first,the CPS structure is presented,which acquires the characteristics of general CPS and enables“simulation-based planning and control”to achieve high level intelligent *** the paper puts forward data fusion estimation algorithm under synchronous and asynchronous sampling,*** experiment shows that global optimal distributed fusion estimation under synchronized sampling proves to be closer to the actual value compared with ordinary weighted estimation,and multi-scale distributed fusion estimation algorithm of wavelet under asynchronous sampling does not need time registration,it can also directly link to data,and the error is *** paper presents hybrid control strategy under the circumstance of joint action of the inner and outer loop to address the problems caused by the less controllable feature of the parallel mechanism when undertaking online process simulation and control.A robust adaptive sliding mode controller is designed based on disturbance observer to restrain inner interference and maintain *** the same time,an outer collaborative trajectory planning is also *** the experiment results show the feasibility of above proposed methods.

关键词： Intelligent aeroplane assembly cyber physical system multi-sensor data fusion simulation-based control disturbance observer robust adaptive sliding mode controller

Data Driven Uncertainty Evaluation for Complex Engineered System Design

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Chinese Journal of Mechanical engineering 2016年第5期29卷 889-900页

作者： LIU Boyuan HUANG Shuangxi FAN Wenhui XIAO Tianyuan James HUMANN LAI Yuyang JIN Yan state cims engineering research center Tsinghua University Beijing 100084 China university of Southern California Los Angeles California USA SOYOTEC Technologies Co. Ltd. Beijing 100081 China

Complex engineered systems are often difficult to analyze and design due to the tangled interdependencies among their subsystems and components. Conventional design methods often need exact modeling or accurate structure decomposition, which limits their practical application. The rapid expansion of data makes utilizing data to guide and improve system design indispensable in practical engineering. In this paper, a data driven uncertainty evaluation approach is proposed to support the design of complex engineered systems. The core of the approach is a data-mining based uncertainty evaluation method that predicts the uncertainty level of a specific system design by means of analyzing association relations along different system attributes and synthesizing the information entropy of the covered attribute areas, and a quantitative measure of system uncertainty can be obtained accordingly. Monte Carlo simulation is introduced to get the uncertainty extrema, and the possible data distributions under different situations is discussed in detail The uncertainty values can be normalized using the simulation results and the values can be used to evaluate different system designs. A prototype system is established, and two case studies have been carded out. The case of an inverted pendulum system validates the effectiveness of the proposed method, and the case of an oil sump design shows the practicability when two or more design plans need to be compared. This research can be used to evaluate the uncertainty of complex engineered systems completely relying on data, and is ideally suited for plan selection and performance analysis in system design.

关键词： complex engineered system design uncertainty data-driven evaluation Monte Carlo simulation

Approach of hybrid GA for multi-objective job-shop scheduling

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International Journal of Modeling, Simulation, and Scientific Computing 2016年第4期7卷 58-67页

作者： Qiaofeng Meng Linxuan Zhang Yushun Fan state cims engineering research center at tsinghua university Beijing 100084 P.R.China

In recent years,scholars have made many research results on job-shop scheduling(JSP)problem,especially in single objective such as the maximum completion *** most of the actual system scheduling problems are more than one ***,the research of multi-objective scheduling problem is very important and *** this paper,we proposed a multi-objective scheduling model which adopts weighted sum method to optimize two important indexes(makespan and total flow time).Genetic algorithm(GA)has diversified global search ability,while simulated annealing(SA)combined with tabu search(TS)have intensified capabilities in local neighborhood *** overcome the drawback of the GA,we proposed a new hybrid GA(NewHGA)which produces initial solutions by GA firstly,and then take SA operator incorporate TS operator to search in the local *** adding the novel local search strategy,the diversity of solutions will be improved greatly so that it can ensure the algorithm jump out of the local optimal *** test this algorithm using the benchmark instances of different sizes taken from the OR-Library,and the results show that the algorithm is efficient than another hybrid algorithm.

关键词： Job shop multiple objectives weighted sum method the maximum completion time total flow time

An Approach to Integrated and Concurrent Product Development

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High Technology Letters 1997年第2期3卷 1-7页

作者：张玉云 The state cims engineering research center Tsinghua University Beijing 100084 P. R. China

A concurrent product development example is used in this paper to introduce a roadmap for integrated and concurrent product development. The roadmap covers the following steps: (1)enterprise problem specifying; (2)information integration modeling; (3)integrated products development team modeling; (4)product development process modeling; and (5) integrated information-process-organization modeling. They have been successfully applied in the major pilot project of "Concurrent engineering" of the 863 Programme of China.

关键词： Concurrent engineering Product development Process re-engineering Product data management Life cycle