Based on the Boltzmann's superposition principles of linear viscoelastic materials and the von Karman's hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of visco...Based on the Boltzmann's superposition principles of linear viscoelastic materials and the von Karman's hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of viscoelastic thin plates was given. By the Galerkin method in spatial domain, the original integro-partial-differential system could be transformed into an integral system. The latter further was reduced to a differential system by using the new method for temporal domain presented in this paper. Numerical results show that compared with the ordinary finite difference method, the new method in this paper is simpler to operate and has some advantages, such as, no storage and quicker computational speed etc.展开更多
In practical fluid dynamic simulations, the bou n dary condition should be treated carefully because it always has crucial influen ce on the numerical accuracy, stability and efficiency. Two types of boundary tr eatme...In practical fluid dynamic simulations, the bou n dary condition should be treated carefully because it always has crucial influen ce on the numerical accuracy, stability and efficiency. Two types of boundary tr eatment methods for lattice Boltzmann method (LBM) are proposed. One is for the treatment of boundaries situated at lattice nodes, and the other is for the appr oximation of boundaries that are not located at the regular lattice nodes. The f irst type of boundary treatment method can deal with various dynamic boundaries on complex geometries by using a general set of formulas, which can maintain sec ond\|order accuracy. Based on the fact that the fluid flows simulated by LBM are not far from equilibrium, the unknown distributions at a boundary node are expr essed as the analogous forms of their corresponding equilibrium distributions. T herefore, the number of unknowns can be reduced and an always\|closed set of equ ations can be obtained for the solutions to pressure, velocity and special bound ary conditions on various geometries. The second type of boundary treatment is a complete interpolation scheme to treat curved boundaries. It comes from careful analysis of the relations between distribution functions at boundary nodes and their neighboring lattice nodes. It is stable for all situations and of second\| order accuracy. Basic ideas, implementation procedures and verifications with ty pical examples for the both treatments are presented. Numerical simulations and analyses show that they are accurate, stable, general and efficient for practica l simulations.展开更多
The developments of Internet and e-commerce provide a new market place to businessman to sell their products and allow people to buy products via Internet as well as to create a new shopping media to consumers. The st...The developments of Internet and e-commerce provide a new market place to businessman to sell their products and allow people to buy products via Internet as well as to create a new shopping media to consumers. The study aims to investigate the factors affecting consumers' purchase decision via Internet and how product characteristics affect cyber shopping in Hong Kong. The study has revealed that the security of personal data,delivery time, product brand and price were the major concerns for developing cyber market. For marketing apparel products, brand loyalty becomes very important since consumers' judging confidence on the products can be increased in terms of fitting standards and quality aspects.展开更多
Process data compression and trending are essential for improving control system performances. Swing Door Trending (SDT) algorithm is well designed to adapt the process trend while retaining the merit of simplicity. B...Process data compression and trending are essential for improving control system performances. Swing Door Trending (SDT) algorithm is well designed to adapt the process trend while retaining the merit of simplicity. But it cannot handle outliers and adapt to the fluctuations of actual data. An Improved SDT (ISDT) algorithm is proposed in this paper. The effectiveness and applicability of the ISDT algorithm are demonstrated by computations on both synthetic and real process data. By applying an adaptive recording limit as well as outliers-detecting rules, a higher compression ratio is achieved and outliers are identified and eliminated. The fidelity of the algorithm is also improved. It can be used both in online and batch mode, and integrated into existing software packages without change.展开更多
Virtual memory management is always a very essential issue of the modern microprocessor design. A memory management unit (MMU) is designed to implement a virtual machine for user programs, and provides a management me...Virtual memory management is always a very essential issue of the modern microprocessor design. A memory management unit (MMU) is designed to implement a virtual machine for user programs, and provides a management mechanism between the operating system and user programs. This paper analyzes the tradeoffs considered in the MMU design of Unity 11 CPU of Peking University, and introduces in detail the solution of pure hardware table walking with two level page table organization. The implementation takes care of required operations and high performances needed by modern operating systems and low costs needed by embedded systems. This solution has been silicon proven, and successfully porting the Linux 2.4.17 kernel, the XWindow system, GNOME and most application software onto the Unity platform.展开更多
The hypotheses of the Karman-Donnell theory of thin shells with large deflections and the Boltzmann laws for isotropic linear, viscoelastic materials, the constitutive equations of shallow shells are first derived. Th...The hypotheses of the Karman-Donnell theory of thin shells with large deflections and the Boltzmann laws for isotropic linear, viscoelastic materials, the constitutive equations of shallow shells are first derived. Then the governing equations for the deflection and stress function are formulated by using the procedure similar to establishing the Karman equations of elastic thin plates. Introducing proper assumptions, an approximate theory for viscoelastic cylindrical shells under axial pressures can be obtained. Finally, the dynamical behavior is studied in detail by using several numerical methods. Dynamical properties, such ns, hyperchaos, chaos, strange attractor, limit cycle etc., are discovered.展开更多
Microprocessor development emphasizes hardware and software co design. Hw/Sw co design is a modern technique aimed at shortening the time to market in designing the real time and embedded systems. Key feature of this ...Microprocessor development emphasizes hardware and software co design. Hw/Sw co design is a modern technique aimed at shortening the time to market in designing the real time and embedded systems. Key feature of this approach is simultaneous development of the program tools and the target processor to match software application. An effective co design flow must therefore support automatic software toolkits generation, without loss of optimizing efficiency. This has resulted in a paradigm shift towards a language based design methodology for microprocessor optimization and exploration. This paper proposes a formal grammar, UNI SPEC, which supports the automatic generation of assemblers, to describe the translation rules from assembly to binary. Based on UNI SPEC, it implements two typical applications, i.e., automatically generating the assembler and the test suites.展开更多
Coupled Hidden Markov Model (CHMM) is the extension of traditional HMM, which is mainly used for complex interactive process modeling such as two-hand gestures. However, the problems of finding optimal model parameter...Coupled Hidden Markov Model (CHMM) is the extension of traditional HMM, which is mainly used for complex interactive process modeling such as two-hand gestures. However, the problems of finding optimal model parameter are still of great interest to the researches in this area. This paper proposes a hybrid genetic algorithm (HGA) for the CHMM training. Chaos is used to initialize GA and used as mutation operator. Experiments on Chinese TaiChi gestures show that standard GA (SGA) based CHMM training is superior to Maximum Likelihood (ML) HMM training. HGA approach has the highest recognition rate of 98.0769%, then 96.1538% for SGA. The last one is ML method, only with a recognition rate of 69.2308%.展开更多
文摘Based on the Boltzmann's superposition principles of linear viscoelastic materials and the von Karman's hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of viscoelastic thin plates was given. By the Galerkin method in spatial domain, the original integro-partial-differential system could be transformed into an integral system. The latter further was reduced to a differential system by using the new method for temporal domain presented in this paper. Numerical results show that compared with the ordinary finite difference method, the new method in this paper is simpler to operate and has some advantages, such as, no storage and quicker computational speed etc.
文摘In practical fluid dynamic simulations, the bou n dary condition should be treated carefully because it always has crucial influen ce on the numerical accuracy, stability and efficiency. Two types of boundary tr eatment methods for lattice Boltzmann method (LBM) are proposed. One is for the treatment of boundaries situated at lattice nodes, and the other is for the appr oximation of boundaries that are not located at the regular lattice nodes. The f irst type of boundary treatment method can deal with various dynamic boundaries on complex geometries by using a general set of formulas, which can maintain sec ond\|order accuracy. Based on the fact that the fluid flows simulated by LBM are not far from equilibrium, the unknown distributions at a boundary node are expr essed as the analogous forms of their corresponding equilibrium distributions. T herefore, the number of unknowns can be reduced and an always\|closed set of equ ations can be obtained for the solutions to pressure, velocity and special bound ary conditions on various geometries. The second type of boundary treatment is a complete interpolation scheme to treat curved boundaries. It comes from careful analysis of the relations between distribution functions at boundary nodes and their neighboring lattice nodes. It is stable for all situations and of second\| order accuracy. Basic ideas, implementation procedures and verifications with ty pical examples for the both treatments are presented. Numerical simulations and analyses show that they are accurate, stable, general and efficient for practica l simulations.
文摘The developments of Internet and e-commerce provide a new market place to businessman to sell their products and allow people to buy products via Internet as well as to create a new shopping media to consumers. The study aims to investigate the factors affecting consumers' purchase decision via Internet and how product characteristics affect cyber shopping in Hong Kong. The study has revealed that the security of personal data,delivery time, product brand and price were the major concerns for developing cyber market. For marketing apparel products, brand loyalty becomes very important since consumers' judging confidence on the products can be increased in terms of fitting standards and quality aspects.
基金The authors would like to acknowledge the support from Project“973”of the State Key Fundamental Research under grant G1998030415.
文摘Process data compression and trending are essential for improving control system performances. Swing Door Trending (SDT) algorithm is well designed to adapt the process trend while retaining the merit of simplicity. But it cannot handle outliers and adapt to the fluctuations of actual data. An Improved SDT (ISDT) algorithm is proposed in this paper. The effectiveness and applicability of the ISDT algorithm are demonstrated by computations on both synthetic and real process data. By applying an adaptive recording limit as well as outliers-detecting rules, a higher compression ratio is achieved and outliers are identified and eliminated. The fidelity of the algorithm is also improved. It can be used both in online and batch mode, and integrated into existing software packages without change.
文摘Virtual memory management is always a very essential issue of the modern microprocessor design. A memory management unit (MMU) is designed to implement a virtual machine for user programs, and provides a management mechanism between the operating system and user programs. This paper analyzes the tradeoffs considered in the MMU design of Unity 11 CPU of Peking University, and introduces in detail the solution of pure hardware table walking with two level page table organization. The implementation takes care of required operations and high performances needed by modern operating systems and low costs needed by embedded systems. This solution has been silicon proven, and successfully porting the Linux 2.4.17 kernel, the XWindow system, GNOME and most application software onto the Unity platform.
基金国家自然科学基金，Development Foundation of Shanghai Municipal Commission of Education，上海市科委资助项目，上海市博士后科研项目
文摘The hypotheses of the Karman-Donnell theory of thin shells with large deflections and the Boltzmann laws for isotropic linear, viscoelastic materials, the constitutive equations of shallow shells are first derived. Then the governing equations for the deflection and stress function are formulated by using the procedure similar to establishing the Karman equations of elastic thin plates. Introducing proper assumptions, an approximate theory for viscoelastic cylindrical shells under axial pressures can be obtained. Finally, the dynamical behavior is studied in detail by using several numerical methods. Dynamical properties, such ns, hyperchaos, chaos, strange attractor, limit cycle etc., are discovered.
文摘Microprocessor development emphasizes hardware and software co design. Hw/Sw co design is a modern technique aimed at shortening the time to market in designing the real time and embedded systems. Key feature of this approach is simultaneous development of the program tools and the target processor to match software application. An effective co design flow must therefore support automatic software toolkits generation, without loss of optimizing efficiency. This has resulted in a paradigm shift towards a language based design methodology for microprocessor optimization and exploration. This paper proposes a formal grammar, UNI SPEC, which supports the automatic generation of assemblers, to describe the translation rules from assembly to binary. Based on UNI SPEC, it implements two typical applications, i.e., automatically generating the assembler and the test suites.
文摘Coupled Hidden Markov Model (CHMM) is the extension of traditional HMM, which is mainly used for complex interactive process modeling such as two-hand gestures. However, the problems of finding optimal model parameter are still of great interest to the researches in this area. This paper proposes a hybrid genetic algorithm (HGA) for the CHMM training. Chaos is used to initialize GA and used as mutation operator. Experiments on Chinese TaiChi gestures show that standard GA (SGA) based CHMM training is superior to Maximum Likelihood (ML) HMM training. HGA approach has the highest recognition rate of 98.0769%, then 96.1538% for SGA. The last one is ML method, only with a recognition rate of 69.2308%.
