The rapid development of computational technology and the increasing energy demand have improved heat exchanger network(HEN)synthesis.The HEN synthesis involves several optimizations of matches,distributions of heat l...The rapid development of computational technology and the increasing energy demand have improved heat exchanger network(HEN)synthesis.The HEN synthesis involves several optimizations of matches,distributions of heat loads,and stream splitting of heat units.Thus,obtaining good results at high efficiency has been the main standard for evaluating the techniques in the research area of HEN synthesis.This paper first summarizes and analyzes the main contributions of the existing HEN synthesis techniques.To compare related data quantitively,information on ten typical cases is presented in this paper.Furthermore,recently improved solutions for commonly encountered existing literature cases demonstrate the evolution and competition trends in the field of HEN synthesis.The comparison data presented in this paper not only provide a useful reference for future research but also present the optimization directions.Based on the findings of this study,it is noted that there is still a large room for improvement,and current approaches are incapable of dealing with all HEN cases.Moreover,it is still difficult to escape a local optimum and overcome structural constraints when seeking the global optimum.As a follow-up to the current work,the parallel computing mode and adaptively coordinating the ratio of global and local searching abilities are major development trends for future investigation.展开更多
The major functions of an engineering-practical expert system(ESW) and the main features of an expert system development tool(QHWEST) for arc welding procedure are introduced. A brief description is given for the deve...The major functions of an engineering-practical expert system(ESW) and the main features of an expert system development tool(QHWEST) for arc welding procedure are introduced. A brief description is given for the development background, process and principal techniques of the two software systems.展开更多
In-situ stress is an essential parameter for design and construction of most engineering projects that involve excavation in rocks. Progress in in-situ stress measurement from the 1950s in China is briefly introduced....In-situ stress is an essential parameter for design and construction of most engineering projects that involve excavation in rocks. Progress in in-situ stress measurement from the 1950s in China is briefly introduced. Stress relief by overcoring technique and hydraulic fracturing： technique are the two main techniques for in-situ stress measurement in China at present. To make them suitable for application at great depth and to increase their measuring reliability and accuracy, a series of techniques have been developed. Applications and achievements of in-situ stress measurement in Chinese rock engineering, including mining, geotechnical and hydropower engineering, and earthquake prediction, are introduced. Suggestions for further development of in-situ stress measurement are also proposed.展开更多
Without the ‘rigid lid’ assumption, the depth averaged linear k-ε model can describe the change of water depth. However, it is incapable of accurately simulating turbulent flows, where the normal Reynolds stresses...Without the ‘rigid lid’ assumption, the depth averaged linear k-ε model can describe the change of water depth. However, it is incapable of accurately simulating turbulent flows, where the normal Reynolds stresses play an important role. A depth averaged nonlinear k-ε model is developed taking into account the stress relations described by Speziale. The depth averaged linear and nonlinear k-ε models can both be used to calculate the flow field near a side discharge into open channel flow, but the results of the nonlinear model are in much closer agreement with experimental results. Furthermore, the technique of changing the 2D linear k-ε program into a depth averaged, nonlinear program is presented.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.21978171 and 51976126)the Capacity Building Plan for some Non-military Universities and Colleges of Shanghai Scientific Committee(Grant Nos.16060502600 and 20060502000)。
文摘The rapid development of computational technology and the increasing energy demand have improved heat exchanger network(HEN)synthesis.The HEN synthesis involves several optimizations of matches,distributions of heat loads,and stream splitting of heat units.Thus,obtaining good results at high efficiency has been the main standard for evaluating the techniques in the research area of HEN synthesis.This paper first summarizes and analyzes the main contributions of the existing HEN synthesis techniques.To compare related data quantitively,information on ten typical cases is presented in this paper.Furthermore,recently improved solutions for commonly encountered existing literature cases demonstrate the evolution and competition trends in the field of HEN synthesis.The comparison data presented in this paper not only provide a useful reference for future research but also present the optimization directions.Based on the findings of this study,it is noted that there is still a large room for improvement,and current approaches are incapable of dealing with all HEN cases.Moreover,it is still difficult to escape a local optimum and overcome structural constraints when seeking the global optimum.As a follow-up to the current work,the parallel computing mode and adaptively coordinating the ratio of global and local searching abilities are major development trends for future investigation.
文摘The major functions of an engineering-practical expert system(ESW) and the main features of an expert system development tool(QHWEST) for arc welding procedure are introduced. A brief description is given for the development background, process and principal techniques of the two software systems.
文摘In-situ stress is an essential parameter for design and construction of most engineering projects that involve excavation in rocks. Progress in in-situ stress measurement from the 1950s in China is briefly introduced. Stress relief by overcoring technique and hydraulic fracturing： technique are the two main techniques for in-situ stress measurement in China at present. To make them suitable for application at great depth and to increase their measuring reliability and accuracy, a series of techniques have been developed. Applications and achievements of in-situ stress measurement in Chinese rock engineering, including mining, geotechnical and hydropower engineering, and earthquake prediction, are introduced. Suggestions for further development of in-situ stress measurement are also proposed.
文摘Without the ‘rigid lid’ assumption, the depth averaged linear k-ε model can describe the change of water depth. However, it is incapable of accurately simulating turbulent flows, where the normal Reynolds stresses play an important role. A depth averaged nonlinear k-ε model is developed taking into account the stress relations described by Speziale. The depth averaged linear and nonlinear k-ε models can both be used to calculate the flow field near a side discharge into open channel flow, but the results of the nonlinear model are in much closer agreement with experimental results. Furthermore, the technique of changing the 2D linear k-ε program into a depth averaged, nonlinear program is presented.
