This paper proposes a policy driven and multi-agent based model to enhance the fault tolerance and recovery capabilities of Web services in distributed environment. The evaluation function of fault specifications and ...This paper proposes a policy driven and multi-agent based model to enhance the fault tolerance and recovery capabilities of Web services in distributed environment. The evaluation function of fault specifications and the corresponding handling mechanisms of the services are both defined in policies, which are expressed in XML. During the implementation of the services,the occurrences of faults are monitored by the service monitor agent through the local knowledge on the faults. Such local knowledge is dynamically generated by the service policy agent through querying and parsing the service policies from the service policies repository. When the fault occurs, the service process agent will focus on the process of fault handling and service recovery, which will be directed with the actions defined in the policies upon the specific conditions. Such a policy driven and multi-agent based fault handling approach can address the issues of flexibility, automation and availability.展开更多
This paper presents a transition-mode zero-voltage-switching inverter for the cooker magnetron of household microwave ovens. The inverter drives a leakage transformer to generate the required high voltage and stabiliz...This paper presents a transition-mode zero-voltage-switching inverter for the cooker magnetron of household microwave ovens. The inverter drives a leakage transformer to generate the required high voltage and stabilized current. For achieving zero-voltage switching, a transition-mode driver L6561 is utilized to detect the ending of transformer resonance and drive an insulated-gate-bipolar-transistor. As transistor is conducted, rectified direct-current voltage drives the transformer. While transistor is cut off, transformer resonates with a parallel capacitor. Transistor conduction time and magnetron power are controlled with a 16-bit digital signal controller dsPIC30F4011. For widening the working range, transistor conduction time is set to be inversely changed with line-frequency input voltage. To demonstrate the analysis and design of this paper, a 1 kW inverter circuit is built. Experimental results show the feasibility and usefulness of the designed magnetron power supply.展开更多
A numerical algorithm using a bilinear or linear finite element and semi-implicit three-step method is presented for the analysis of incompressible viscous fluid problems. The streamline upwind/Petrov-Galerkin (SUPG) ...A numerical algorithm using a bilinear or linear finite element and semi-implicit three-step method is presented for the analysis of incompressible viscous fluid problems. The streamline upwind/Petrov-Galerkin (SUPG) stabilization scheme is used for the formulation of the Navier-Stokes equations. For the spatial discretization, the convection term is treated explicitly, while the viscous term is treated implicitly, and for the temporal discretization, a three-step method is employed. The present method is applied to simulate the lid driven cavity problems with different geometries at low and high Reynolds numbers. The results compared with other numerical experiments are found to be feasible and satisfactory.展开更多
文摘This paper proposes a policy driven and multi-agent based model to enhance the fault tolerance and recovery capabilities of Web services in distributed environment. The evaluation function of fault specifications and the corresponding handling mechanisms of the services are both defined in policies, which are expressed in XML. During the implementation of the services,the occurrences of faults are monitored by the service monitor agent through the local knowledge on the faults. Such local knowledge is dynamically generated by the service policy agent through querying and parsing the service policies from the service policies repository. When the fault occurs, the service process agent will focus on the process of fault handling and service recovery, which will be directed with the actions defined in the policies upon the specific conditions. Such a policy driven and multi-agent based fault handling approach can address the issues of flexibility, automation and availability.
文摘This paper presents a transition-mode zero-voltage-switching inverter for the cooker magnetron of household microwave ovens. The inverter drives a leakage transformer to generate the required high voltage and stabilized current. For achieving zero-voltage switching, a transition-mode driver L6561 is utilized to detect the ending of transformer resonance and drive an insulated-gate-bipolar-transistor. As transistor is conducted, rectified direct-current voltage drives the transformer. While transistor is cut off, transformer resonates with a parallel capacitor. Transistor conduction time and magnetron power are controlled with a 16-bit digital signal controller dsPIC30F4011. For widening the working range, transistor conduction time is set to be inversely changed with line-frequency input voltage. To demonstrate the analysis and design of this paper, a 1 kW inverter circuit is built. Experimental results show the feasibility and usefulness of the designed magnetron power supply.
基金Project supported by the National Natural Science Foundation of China (No.51078230)the Research Fund for the Doctoral Program of Higher Education of China (No.200802480056)the Key Project of Fund of Science and Technology Development of Shanghai (No.10JC1407900),China
文摘A numerical algorithm using a bilinear or linear finite element and semi-implicit three-step method is presented for the analysis of incompressible viscous fluid problems. The streamline upwind/Petrov-Galerkin (SUPG) stabilization scheme is used for the formulation of the Navier-Stokes equations. For the spatial discretization, the convection term is treated explicitly, while the viscous term is treated implicitly, and for the temporal discretization, a three-step method is employed. The present method is applied to simulate the lid driven cavity problems with different geometries at low and high Reynolds numbers. The results compared with other numerical experiments are found to be feasible and satisfactory.
