Flows of polymeric liquids undergo instabilities whose origins are quite different from those of Newtonian flows, due to their elastic character and the complexity of the fluid/solid boundary condition. One of these i...Flows of polymeric liquids undergo instabilities whose origins are quite different from those of Newtonian flows, due to their elastic character and the complexity of the fluid/solid boundary condition. One of these instabilities is well known as “shark-skin” which damages the surface appearance and properties of polymer extrudate while processing in blowmolding or piping, while it can be suppressed by employing various methods including coating the die surface and/or adding Polymer Processing Aid’s (PPA) to the polymer. In this article, the effect of various die materials on the properties of Polyethylene glycol (PEG) as a new type of PPA for suppressing the sharkskin phenomenon has been studied.展开更多
A multi agent computer aided assembly process planning system (MCAAPP) for ship hull is presented. The system includes system framework, global facilitator, the macro agent structure, agent communication language, ag...A multi agent computer aided assembly process planning system (MCAAPP) for ship hull is presented. The system includes system framework, global facilitator, the macro agent structure, agent communication language, agent oriented programming language, knowledge representation and reasoning strategy. The system can produce the technological file and technological quota, which can satisfy the production needs of factory.展开更多
Process planning and scheduling are two major plann in g and control activities that consume significant part of the lead-time, theref ore all attempts are being made to reduce lead-time by automating them. Compute r ...Process planning and scheduling are two major plann in g and control activities that consume significant part of the lead-time, theref ore all attempts are being made to reduce lead-time by automating them. Compute r Aided Process Planning (CAPP) is a step in this direction. Most of the existin g CAPP systems do not consider scheduling while generating a process plan. Sched uling is done separately after the process plan has been generated and therefore , it is possible that a process plan so generated is either not optimal or feasi ble from scheduling point of view. As process plans are generated without consid eration of job shop status, many problems arise within the manufacturing environ ment. Investigations have shown that 20%～30% of all process plans generated are not valid and have to be altered or suffer production delays when production sta rts. There is thus a major need for integration of scheduling with computer aide d process planning for generating more realistic process plans. In doing so, eff iciency of the manufacturing system as a whole is expected to improve. Decision support system performs many functions such as selection of machine too ls, cutting tools, sequencing of operations, determination of optimum cutting pa rameters and checking availability of machine tool before allocating any operati on to a machine tool. The process of transforming component data, process capabi lity and decision rules into computer readable format is still a major obstacle. This paper proposes architecture of a system, which integrates computer aided p rocess-planning system with scheduling using decision support system. A decisio n support system can be defined as " an interactive system that provides the use rs with easy access to decision models in order to support semi-structured or u nstructured decision making tasks".展开更多
Expert consensus proposes an emergency treatment protocol for portal hypertension bleeding. Herein, the emergency treatment procedures, which include first aid, medical, interventional, and surgical treatments, are de...Expert consensus proposes an emergency treatment protocol for portal hypertension bleeding. Herein, the emergency treatment procedures, which include first aid, medical, interventional, and surgical treatments, are described. In addition, the indications, contraindications, operating norms, precautions, and prevention of complications of portal hypertension are described to optimize the first aid process.展开更多
In this paper, the generative approach utilizes recursion to generate process sequence for a part, and then match detail procedure design and select process equipment. A set of recursive formulas are found. Finally ...In this paper, the generative approach utilizes recursion to generate process sequence for a part, and then match detail procedure design and select process equipment. A set of recursive formulas are found. Finally a complete process program is produced. The method is simple than that of the knowledge system, the artificial neural networks and variant approach computer aided process planning(VACAPP).展开更多
The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size,...The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size, machining range, machining precision and surface roughness. By means of fuzzy comprehensive evaluation method, the membership degree of machine tool selection and the largest comprehensive evaluation index are determined. Then the reasonably automatic selection of machine tool is realized in the generative computer aided process planning （CAPP） system. Finally, the finite element model based on ABAQUS is established and the cutting process of machine tool is simulated. According to the theoretical and empirical cutting parameters and the curve of surface residual stress, the optimal cutting parameters can be determined.展开更多
THCAPP is a computer aided process planning system for non-rotational parts which runs in a CIMS (computer integrated manufacturing system ) environment at Tsinghua University. Its architecture is described in this pa...THCAPP is a computer aided process planning system for non-rotational parts which runs in a CIMS (computer integrated manufacturing system ) environment at Tsinghua University. Its architecture is described in this paper. Then its main functions and key techniques, including part modeling, generative process planning and integration with CAD (computer aided design) and CAM (computer aided manufacturing) ale discussed in detail.展开更多
Computer aided process planning (CAPP) aims at improving efficiency, quality, and productivity in a manufacturing concern through reducing lead times and costs by utilizing better manufacturing practices thus improvin...Computer aided process planning (CAPP) aims at improving efficiency, quality, and productivity in a manufacturing concern through reducing lead times and costs by utilizing better manufacturing practices thus improving competitiveness in the market. CAPP attempts to capture the thoughts and methods of the experienced process planner. Variant systems are understandable, generative systems can plan new parts. Expert systems increase flexibility, fuzzy logic captures vague knowledge while neural networks learn. The combination of fuzzy, neural and expert system technologies is necessary to capture and utilize the process planning logic. A system that maintains the dependability and clarity of variant systems, is capable of planning new parts, and improves itself through learning is needed by industry.展开更多
Since existing computer aided process planning (CAPP) systems have shortcomings such as difficultknowledge-acquisition, low intelligence level, weak optimization capability, etc.the application of artificial neuralnet...Since existing computer aided process planning (CAPP) systems have shortcomings such as difficultknowledge-acquisition, low intelligence level, weak optimization capability, etc.the application of artificial neuralnetworks (ANN) may significantly increase CAPP capabilities.Since ANN is self-learning, ANN has remarkable advantages in representing and acquiring of technical knowledge (especially that which is difficult to symbolize). In addition, since many procedures in CAPP are essentially optimization, ANN's combinatorial optimization capability canbe very useful.Both of these aspects of applying ANN to CAPP are described using an example which deals with process planning for machining of mechanical components.展开更多
Automatic fixture design is a key link in computer aided process planning. The uncertainty in the selection of fixture design schemes necessitates the use of the fuzzy comprehensive judgment method to automatically se...Automatic fixture design is a key link in computer aided process planning. The uncertainty in the selection of fixture design schemes necessitates the use of the fuzzy comprehensive judgment method to automatically select an optimal fixture design. This paper reports on the development of a computer aided fixture design system for non rotational parts using the fuzzy comprehensive judgment method running in an integrated process planning environment. Several typical non rotational parts with complicated configurations are used to demonstrate the automatic fixture design system.展开更多
文摘Flows of polymeric liquids undergo instabilities whose origins are quite different from those of Newtonian flows, due to their elastic character and the complexity of the fluid/solid boundary condition. One of these instabilities is well known as “shark-skin” which damages the surface appearance and properties of polymer extrudate while processing in blowmolding or piping, while it can be suppressed by employing various methods including coating the die surface and/or adding Polymer Processing Aid’s (PPA) to the polymer. In this article, the effect of various die materials on the properties of Polyethylene glycol (PEG) as a new type of PPA for suppressing the sharkskin phenomenon has been studied.
文摘A multi agent computer aided assembly process planning system (MCAAPP) for ship hull is presented. The system includes system framework, global facilitator, the macro agent structure, agent communication language, agent oriented programming language, knowledge representation and reasoning strategy. The system can produce the technological file and technological quota, which can satisfy the production needs of factory.
文摘Process planning and scheduling are two major plann in g and control activities that consume significant part of the lead-time, theref ore all attempts are being made to reduce lead-time by automating them. Compute r Aided Process Planning (CAPP) is a step in this direction. Most of the existin g CAPP systems do not consider scheduling while generating a process plan. Sched uling is done separately after the process plan has been generated and therefore , it is possible that a process plan so generated is either not optimal or feasi ble from scheduling point of view. As process plans are generated without consid eration of job shop status, many problems arise within the manufacturing environ ment. Investigations have shown that 20%～30% of all process plans generated are not valid and have to be altered or suffer production delays when production sta rts. There is thus a major need for integration of scheduling with computer aide d process planning for generating more realistic process plans. In doing so, eff iciency of the manufacturing system as a whole is expected to improve. Decision support system performs many functions such as selection of machine too ls, cutting tools, sequencing of operations, determination of optimum cutting pa rameters and checking availability of machine tool before allocating any operati on to a machine tool. The process of transforming component data, process capabi lity and decision rules into computer readable format is still a major obstacle. This paper proposes architecture of a system, which integrates computer aided p rocess-planning system with scheduling using decision support system. A decisio n support system can be defined as " an interactive system that provides the use rs with easy access to decision models in order to support semi-structured or u nstructured decision making tasks".
基金supported by the Key Science and Technology Project of Hunan Province:Key Technology Collaborative Innovation Project of Improving Emergency and Critical Care Ability and Public Health Emergency Treatment in Hunan Province (2020SK1010)。
文摘Expert consensus proposes an emergency treatment protocol for portal hypertension bleeding. Herein, the emergency treatment procedures, which include first aid, medical, interventional, and surgical treatments, are described. In addition, the indications, contraindications, operating norms, precautions, and prevention of complications of portal hypertension are described to optimize the first aid process.
文摘In this paper, the generative approach utilizes recursion to generate process sequence for a part, and then match detail procedure design and select process equipment. A set of recursive formulas are found. Finally a complete process program is produced. The method is simple than that of the knowledge system, the artificial neural networks and variant approach computer aided process planning(VACAPP).
基金Shanxi Province Science and Technology Research Project(No.20140321008-03)
文摘The paper analyzes the factors influencing machine tool selection. By using fuzzy mathematics theory, we establish a theorietical model for optimal machine tool selection considering geometric features, clamping size, machining range, machining precision and surface roughness. By means of fuzzy comprehensive evaluation method, the membership degree of machine tool selection and the largest comprehensive evaluation index are determined. Then the reasonably automatic selection of machine tool is realized in the generative computer aided process planning （CAPP） system. Finally, the finite element model based on ABAQUS is established and the cutting process of machine tool is simulated. According to the theoretical and empirical cutting parameters and the curve of surface residual stress, the optimal cutting parameters can be determined.
文摘THCAPP is a computer aided process planning system for non-rotational parts which runs in a CIMS (computer integrated manufacturing system ) environment at Tsinghua University. Its architecture is described in this paper. Then its main functions and key techniques, including part modeling, generative process planning and integration with CAD (computer aided design) and CAM (computer aided manufacturing) ale discussed in detail.
文摘Computer aided process planning (CAPP) aims at improving efficiency, quality, and productivity in a manufacturing concern through reducing lead times and costs by utilizing better manufacturing practices thus improving competitiveness in the market. CAPP attempts to capture the thoughts and methods of the experienced process planner. Variant systems are understandable, generative systems can plan new parts. Expert systems increase flexibility, fuzzy logic captures vague knowledge while neural networks learn. The combination of fuzzy, neural and expert system technologies is necessary to capture and utilize the process planning logic. A system that maintains the dependability and clarity of variant systems, is capable of planning new parts, and improves itself through learning is needed by industry.
文摘Since existing computer aided process planning (CAPP) systems have shortcomings such as difficultknowledge-acquisition, low intelligence level, weak optimization capability, etc.the application of artificial neuralnetworks (ANN) may significantly increase CAPP capabilities.Since ANN is self-learning, ANN has remarkable advantages in representing and acquiring of technical knowledge (especially that which is difficult to symbolize). In addition, since many procedures in CAPP are essentially optimization, ANN's combinatorial optimization capability canbe very useful.Both of these aspects of applying ANN to CAPP are described using an example which deals with process planning for machining of mechanical components.
文摘Automatic fixture design is a key link in computer aided process planning. The uncertainty in the selection of fixture design schemes necessitates the use of the fuzzy comprehensive judgment method to automatically select an optimal fixture design. This paper reports on the development of a computer aided fixture design system for non rotational parts using the fuzzy comprehensive judgment method running in an integrated process planning environment. Several typical non rotational parts with complicated configurations are used to demonstrate the automatic fixture design system.
