2002 Vol.15(1)
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2002, 16(1).
Abstract:
Performance and reliability experiments on BJD-6100EV electric buses, jointly developed by Beijing Institute of Technology and Beijing Public Transport Company, are introduced. Output power model of battery pack is established and maximum output power is analyzed. A permanent magnetic direct current (PMDC) motor with enhanced windings is developed for the bus. Torque-speed characteristics of the motor are modeled and performance of electric bus is analyzed. Computational method of the range of electric bus is proposed and discussed. Experiments show that electric bus can realize design requirements. Computational methods are verified with the help of field test. It is expected that design and computation method will provide helpful reference to development of electric vehicles.
Performance and reliability experiments on BJD-6100EV electric buses, jointly developed by Beijing Institute of Technology and Beijing Public Transport Company, are introduced. Output power model of battery pack is established and maximum output power is analyzed. A permanent magnetic direct current (PMDC) motor with enhanced windings is developed for the bus. Torque-speed characteristics of the motor are modeled and performance of electric bus is analyzed. Computational method of the range of electric bus is proposed and discussed. Experiments show that electric bus can realize design requirements. Computational methods are verified with the help of field test. It is expected that design and computation method will provide helpful reference to development of electric vehicles.
2002, 16(1).
Abstract:
Gate type selection is very important for mould design. Improper gate type may lead to poor product quality and low production efficiency. Although numerical simulation approach could be used to optimize gate location, the determination of gate type is still up to designers' experience. A novel method for selecting gate type based on fuzzy logic is proposed. The proposed methodology follows three steps：Design requirements for gate is extracted and generalized; Possible gate types (design schemes) are presented; The fuzzy mapping relationship between gate design requirements and gate design scheme is established based on fuzzy composition and fuzzy relation transition matrices that are assigned by domain experts.
Gate type selection is very important for mould design. Improper gate type may lead to poor product quality and low production efficiency. Although numerical simulation approach could be used to optimize gate location, the determination of gate type is still up to designers' experience. A novel method for selecting gate type based on fuzzy logic is proposed. The proposed methodology follows three steps：Design requirements for gate is extracted and generalized; Possible gate types (design schemes) are presented; The fuzzy mapping relationship between gate design requirements and gate design scheme is established based on fuzzy composition and fuzzy relation transition matrices that are assigned by domain experts.
2002, 16(1).
Abstract:
A new method is put forward combining computer vision with computer aided geometric design (CAGD) to resolve the problem of free-form surface reconstruction. The surface is first subdivided into N-sided Gregory patches, and a stereo algorithm is used to reconstruct the boundary curves. Then, the cross boundary tangent vectors are computed through reflectance analysis. At last, the whole surface can be reconstructed jointing these patches with G1 continuity(tangent continuity). Examples on synthetic images are given.
A new method is put forward combining computer vision with computer aided geometric design (CAGD) to resolve the problem of free-form surface reconstruction. The surface is first subdivided into N-sided Gregory patches, and a stereo algorithm is used to reconstruct the boundary curves. Then, the cross boundary tangent vectors are computed through reflectance analysis. At last, the whole surface can be reconstructed jointing these patches with G1 continuity(tangent continuity). Examples on synthetic images are given.
2002, 16(1).
Abstract:
The requirements and features of virtual assembly movement navigator are analyzed to help operators flexibly manipulate virtual objects, precisely locate or assemble virtual parts in virtual environment. With the degree-of-freedom analysis, the assembly constraint hierarchical model is constructed and the system's constraints are built dynamically. Thus, all objects in virtual environment can be located reasonally by the navigator. Moreover, the assembly constraint recognition in the process of assembly and movement correction is also discussed.
The requirements and features of virtual assembly movement navigator are analyzed to help operators flexibly manipulate virtual objects, precisely locate or assemble virtual parts in virtual environment. With the degree-of-freedom analysis, the assembly constraint hierarchical model is constructed and the system's constraints are built dynamically. Thus, all objects in virtual environment can be located reasonally by the navigator. Moreover, the assembly constraint recognition in the process of assembly and movement correction is also discussed.
2002, 16(1).
Abstract:
Computer vision and its application in the precision control system are discussed. In the process of fabricating, the accuracy of the products should be controlled reasonably and completely. The precison should be kept and adjusted according to the information of feedback got from the measurement on-line or out-line in different procedures. Computer vision is one of the useful methods to do this. Computer vision and the image manipulation are presented, and based on this, a n-dimensional vector to appraise on prescision of machining is given.
Computer vision and its application in the precision control system are discussed. In the process of fabricating, the accuracy of the products should be controlled reasonably and completely. The precison should be kept and adjusted according to the information of feedback got from the measurement on-line or out-line in different procedures. Computer vision is one of the useful methods to do this. Computer vision and the image manipulation are presented, and based on this, a n-dimensional vector to appraise on prescision of machining is given.
2002, 16(1).
Abstract:
3-D rigid visco-plastic finite element method (FEM) is used in the analysis of metal forming processes, including strip and plate rolling, shape rolling, slab edging, special strip rolling. The shifted incomplete Cholesky decomposition of the stiffness matrix with the solution of the equations for velocity increment by the conjugate gradient method is combined. This technique, termed the shifted ICCG method, is then employed to solve the slab edging problem. The performance of this algorithm in terms of the number of iterations, friction variation, shifted parameter and the results of simulation for processing parameters are analysed. Numerical tests and application of this technique verify the efficiency and stability of the shifted ICCG method in the analysis of slab edging.
3-D rigid visco-plastic finite element method (FEM) is used in the analysis of metal forming processes, including strip and plate rolling, shape rolling, slab edging, special strip rolling. The shifted incomplete Cholesky decomposition of the stiffness matrix with the solution of the equations for velocity increment by the conjugate gradient method is combined. This technique, termed the shifted ICCG method, is then employed to solve the slab edging problem. The performance of this algorithm in terms of the number of iterations, friction variation, shifted parameter and the results of simulation for processing parameters are analysed. Numerical tests and application of this technique verify the efficiency and stability of the shifted ICCG method in the analysis of slab edging.
2002, 16(1).
Abstract:
The automatic control of clutch starting in car with a metal pushing belt-planetary gear continuously variable transmission (CVT) is a complex problem. A suited control strategy is required to realize quick and smooth start. A simulation state space equation is established on clutch starting control of a car with CVT by bond graph theory. According to the fuzzy control method with the expert system, a fuzzy control system of car starting process to weaken the jerk motion is introduced. The simulation results indicate that the jerk motion of clutch starting is below 10 m/s3.
The automatic control of clutch starting in car with a metal pushing belt-planetary gear continuously variable transmission (CVT) is a complex problem. A suited control strategy is required to realize quick and smooth start. A simulation state space equation is established on clutch starting control of a car with CVT by bond graph theory. According to the fuzzy control method with the expert system, a fuzzy control system of car starting process to weaken the jerk motion is introduced. The simulation results indicate that the jerk motion of clutch starting is below 10 m/s3.
2002, 16(1).
Abstract:
The extended enterprise is formed according to the philosophy of dispersed networked manufacturing. Manufacturing execution system (MES) can close the information gap which exists between device control system and production information management system. The functions and the web-based architecture of the MES in the extended enterprise are introduced. Using the cooperating system models of object-oriented and distributed agents and CORBA, all objects keep to uniform interface standards and are easily inserted to object request broker. The utilization of distributed MES in extended enterprise can adapt fast change of manufacturing environment and resource. It also can improve the independent management capability of manufacturing cell and the enterprise response capability to global economic competition.
The extended enterprise is formed according to the philosophy of dispersed networked manufacturing. Manufacturing execution system (MES) can close the information gap which exists between device control system and production information management system. The functions and the web-based architecture of the MES in the extended enterprise are introduced. Using the cooperating system models of object-oriented and distributed agents and CORBA, all objects keep to uniform interface standards and are easily inserted to object request broker. The utilization of distributed MES in extended enterprise can adapt fast change of manufacturing environment and resource. It also can improve the independent management capability of manufacturing cell and the enterprise response capability to global economic competition.
2002, 16(1).
Abstract:
A cyclic plasticity model is used into finite element (FE) method to obtain the details of elastic-plastic stress-strain in the bolts under cyclic axial loading. Two criteria in multiaxial fatigue are employed to predict fatigue lives of bolts. The predicted fatigue lives are in favorable agreement with the experimental results for machined bolts.
A cyclic plasticity model is used into finite element (FE) method to obtain the details of elastic-plastic stress-strain in the bolts under cyclic axial loading. Two criteria in multiaxial fatigue are employed to predict fatigue lives of bolts. The predicted fatigue lives are in favorable agreement with the experimental results for machined bolts.
2002, 16(1).
Abstract:
Green sand casting is still a main method in the world at present and it is very significant to develop the technology of controlling green sand quality. A new concept, from contents test to contents control, is advanced. In order to realize the new idea, a new method to on-line test active clay and moisture of green sand - double powers energizing alternately (DPEA) method is put forwards. The principle of the new method is to energize standard sand sample with AC and DC powers and to test the electric parameters, and then, to calculate active clay and moisture of green sand by using artificial neural network (ANN). Based on this new method, a direct optimizing system for controlling green sand quality is developed. Techniques about testing and controlling methods, hardware and software are discussed.
Green sand casting is still a main method in the world at present and it is very significant to develop the technology of controlling green sand quality. A new concept, from contents test to contents control, is advanced. In order to realize the new idea, a new method to on-line test active clay and moisture of green sand - double powers energizing alternately (DPEA) method is put forwards. The principle of the new method is to energize standard sand sample with AC and DC powers and to test the electric parameters, and then, to calculate active clay and moisture of green sand by using artificial neural network (ANN). Based on this new method, a direct optimizing system for controlling green sand quality is developed. Techniques about testing and controlling methods, hardware and software are discussed.
2002, 16(1).
Abstract:
An effect of unequal deformation in development of advanced plastic processing technologies is researched by studying an in-plane bending process of strip metal under unequal compressing. The research results show the following：If appropriately controlled, unequal plastic deformation can play an important role not only in the improvement of quality of parts obtained by plastic processing technologies, but also in the development of new processes for advanced plastic working technologies. A coordinated growth of unequal plastic deformation can develop the deformation potentiality of material to the full. The degree of unequal plastic deformation can be used as bases for optimization design of processes and dies of plastic forming.
An effect of unequal deformation in development of advanced plastic processing technologies is researched by studying an in-plane bending process of strip metal under unequal compressing. The research results show the following：If appropriately controlled, unequal plastic deformation can play an important role not only in the improvement of quality of parts obtained by plastic processing technologies, but also in the development of new processes for advanced plastic working technologies. A coordinated growth of unequal plastic deformation can develop the deformation potentiality of material to the full. The degree of unequal plastic deformation can be used as bases for optimization design of processes and dies of plastic forming.
2002, 16(1).
Abstract:
Numerical instabilities are often encountered in FE solution of continuum topology optimization. The essence of the numerical instabilities is given from the inverse partial differential equation (PDE) point of view. On the basis of the strict mathematical theory, a novel method, named as window filter and multi-grid method, which solves the numerical instabilities, is proposed. Convergent analyses and a numerical example are presented.
Numerical instabilities are often encountered in FE solution of continuum topology optimization. The essence of the numerical instabilities is given from the inverse partial differential equation (PDE) point of view. On the basis of the strict mathematical theory, a novel method, named as window filter and multi-grid method, which solves the numerical instabilities, is proposed. Convergent analyses and a numerical example are presented.
2002, 16(1).
Abstract:
The basic principle of modern design of cylindrical gear drive based on the Internet is described. The methods of optimized design, finite element analysis, CAD design and web design as well as research and development entity of three parties such as institute research unit (or university), enterprise and customer are also studied. Its purpose is to provide a necessary foundation for realizing the design of cylindrical gear drive from different location on the modern Internet and to explore a practice application route.
The basic principle of modern design of cylindrical gear drive based on the Internet is described. The methods of optimized design, finite element analysis, CAD design and web design as well as research and development entity of three parties such as institute research unit (or university), enterprise and customer are also studied. Its purpose is to provide a necessary foundation for realizing the design of cylindrical gear drive from different location on the modern Internet and to explore a practice application route.
2002, 16(1).
Abstract:
The following questions are discussed：feature cluster, feature cluster concept and the reasoning formula. The defect based on approach direction and feed direction are analyzed. Feature tool axis direction concept and its definition method are submitted. The feature for practical part is also clustered by tool axis direction.
The following questions are discussed：feature cluster, feature cluster concept and the reasoning formula. The defect based on approach direction and feed direction are analyzed. Feature tool axis direction concept and its definition method are submitted. The feature for practical part is also clustered by tool axis direction.
2002, 16(1).
Abstract:
The key problem in the construction of virtual enterprises (Ves) is how to select appropriate partners. The negotiation-based approach is proposed to support partner selection in the construction of Ves . The negotiation model is discussed from three main aspects respectively,I.e., negotiation protocol, negotiation goal and negotiation decision-making model. And the generic mathematical description of the negotiation model is formally presented. Finally, a simple example is used to validate the approach's availability.
The key problem in the construction of virtual enterprises (Ves) is how to select appropriate partners. The negotiation-based approach is proposed to support partner selection in the construction of Ves . The negotiation model is discussed from three main aspects respectively,I.e., negotiation protocol, negotiation goal and negotiation decision-making model. And the generic mathematical description of the negotiation model is formally presented. Finally, a simple example is used to validate the approach's availability.
2002, 16(1).
Abstract:
The optimal control to a partially controlled turbogenerator shaft torsional vibration system is investigated. The principle of input feedforward control is presented to achieve the minimum of the average vibration energy in a system，and the optimal control matrix of the system is derived. A turbogenerator shaft system is taken as an example to simulate the optimal control process of the torsional vibration. Results from this simulation indicate that the vibration can be effectively controlled by a partial control strategy.
The optimal control to a partially controlled turbogenerator shaft torsional vibration system is investigated. The principle of input feedforward control is presented to achieve the minimum of the average vibration energy in a system，and the optimal control matrix of the system is derived. A turbogenerator shaft system is taken as an example to simulate the optimal control process of the torsional vibration. Results from this simulation indicate that the vibration can be effectively controlled by a partial control strategy.
2002, 16(1).
Abstract:
Some concepts of virtual product are discussed. The key technologies of virtual fuel-pump development are in detail analysed, which include virtual fuel-pump product modeling, intelligent simulation, distributed design environment, and virtual assembly. The virtual fuel-pump development prototype system considers requirement analysis, concept design, injection preferment analysis, detailed design, and assembly analysis.
Some concepts of virtual product are discussed. The key technologies of virtual fuel-pump development are in detail analysed, which include virtual fuel-pump product modeling, intelligent simulation, distributed design environment, and virtual assembly. The virtual fuel-pump development prototype system considers requirement analysis, concept design, injection preferment analysis, detailed design, and assembly analysis.
2002, 16(1).
Abstract:
The applicability of shape memory alloys (SMAs) in structural dynamics, particularly as hysteretic damping elements, is limited by the difficulties in modelling their deformation characteristics. At typical engineering design levels of loading SMAs exhibit pseudo-elastic properties. A combined experimental and simulation approach suitable for the characterisation of novel smart devices based on the pseudo-elastic effect is described.
The applicability of shape memory alloys (SMAs) in structural dynamics, particularly as hysteretic damping elements, is limited by the difficulties in modelling their deformation characteristics. At typical engineering design levels of loading SMAs exhibit pseudo-elastic properties. A combined experimental and simulation approach suitable for the characterisation of novel smart devices based on the pseudo-elastic effect is described.
2002, 16(1).
Abstract:
An artificial neural network(ANN) and a self-adjusting fuzzy logic controller(FLC) for modeling and control of gas tungsten arc welding(GTAW) process are presented. The discussion is mainly focused on the modeling and control of the weld pool depth with ANN and the intelligent control for weld seam tracking with FLC. The proposed neural network can produce highly complex nonlinear multi-variable model of the GTAW process that offers the accurate prediction of welding penetration depth. A self-adjusting fuzzy controller used for seam tracking adjusts the control parameters on-line automatically according to the tracking errors so that the torch position can be controlled accurately.
An artificial neural network(ANN) and a self-adjusting fuzzy logic controller(FLC) for modeling and control of gas tungsten arc welding(GTAW) process are presented. The discussion is mainly focused on the modeling and control of the weld pool depth with ANN and the intelligent control for weld seam tracking with FLC. The proposed neural network can produce highly complex nonlinear multi-variable model of the GTAW process that offers the accurate prediction of welding penetration depth. A self-adjusting fuzzy controller used for seam tracking adjusts the control parameters on-line automatically according to the tracking errors so that the torch position can be controlled accurately.
2002, 16(1).
Abstract:
Through the comparison study on cutting force, cutting temperature and machined surface quality with the sub-dry cutting traditional cooling method, it is shown that sub-dry cutting can retard the wear of the tooled parts. It is beneficial to realize the production without pollution and meet the demand of clean environment.
Through the comparison study on cutting force, cutting temperature and machined surface quality with the sub-dry cutting traditional cooling method, it is shown that sub-dry cutting can retard the wear of the tooled parts. It is beneficial to realize the production without pollution and meet the demand of clean environment.
2002, 16(1).
Abstract:
The mechanical reliability and optimization theory on the method of reliability-optimization design for the new roller orientation clutch is provided. The result of reliability-optimization design is compared with the result of the conventional design method.
The mechanical reliability and optimization theory on the method of reliability-optimization design for the new roller orientation clutch is provided. The result of reliability-optimization design is compared with the result of the conventional design method.
2002, 16(1).
Abstract:
In allusion to the deficient feature of product information in conceptual design, a framework of deficient information modeling for conceptual shape design is put forward, which includes qualitative shape modeling (a qualitative solid model), uncertain shape modeling (an uncertain relation model) and imprecise shape modeling (an imprecise region model). In the framework, the qualitative solid model is the core, which represents qualitatively (using symbols) the conceptual shapes of mechanical products. The uncertain relation model regarding domain relations as objects and the imprecise region model regarding domains as objects are used to deal with the uncertain and imprecise issues respectively, which arise from qualitative shape modeling or exist in product information itself.
In allusion to the deficient feature of product information in conceptual design, a framework of deficient information modeling for conceptual shape design is put forward, which includes qualitative shape modeling (a qualitative solid model), uncertain shape modeling (an uncertain relation model) and imprecise shape modeling (an imprecise region model). In the framework, the qualitative solid model is the core, which represents qualitatively (using symbols) the conceptual shapes of mechanical products. The uncertain relation model regarding domain relations as objects and the imprecise region model regarding domains as objects are used to deal with the uncertain and imprecise issues respectively, which arise from qualitative shape modeling or exist in product information itself.
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