This paper proposes a new high-performance switching element with the new shared-memory queuing policy, which is called blocked-cell shared-memory (BCSM) queuing. As the name means, instead of buffering all cells thro...This paper proposes a new high-performance switching element with the new shared-memory queuing policy, which is called blocked-cell shared-memory (BCSM) queuing. As the name means, instead of buffering all cells through them, the BCSM switching elements only buffer the blocked cells at their input ports. Theoretic analysis results under the uniform traffic model prove that BCSM switching elements have better performance than shared-memory switching elements.展开更多
In this communication we propose a method to implement an all-optical astable multivibrator using the non-linear material based switches and logic gates. The scheme can operate in real time. The delay time can achieve...In this communication we propose a method to implement an all-optical astable multivibrator using the non-linear material based switches and logic gates. The scheme can operate in real time. The delay time can achieve ps(pico-second). The pulse duration can be made very low and may cross the THz easily by selecting proper material and laser source.展开更多
A nonlinear finite element （FE） model based on domain switching was proposed to study the electromechanical behavior of ferroelectric ceramics. The incremental FE formulation was improved to avoid any calculation in...A nonlinear finite element （FE） model based on domain switching was proposed to study the electromechanical behavior of ferroelectric ceramics. The incremental FE formulation was improved to avoid any calculation instability. The problems of mesh sensitivity and convergence, and the efficiency of the proposed nonlinear FE technique have been assessed to illustrate the versatility and potential accuracy of the said technique. The nonlinear electromechanical behavior, such as the hysteresis loops and butterfly curves, of ferroelectric ceramics subjected to both a uniform electric field and a point electric potential has been studied numerically. The results obtained are in good agreement with those of the corresponding theoretical and experimental analyses. Furthermore, the electromechanical coupling fields near （a） the boundary of a circular hole, （b） the boundary of an elliptic hole and （c） the tip of a crack, have been analyzed using the proposed nonlinear finite element method （FEM）. The proposed nonlinear electromechanically coupled FEM is useful for the analysis of domain switching, deformation and fracture of ferroelectric ceramics.展开更多
A micromechanics-based finite element model for the constitutive behavior of polycrystalline ferromagnets is developed. In the model, the polycrystalline solid is assumed to comprise numerous single crystals with rand...A micromechanics-based finite element model for the constitutive behavior of polycrystalline ferromagnets is developed. In the model, the polycrystalline solid is assumed to comprise numerous single crystals with randomly distributed crystallographic orientations, and the single crystals, in turn, consist of ferromagnetic domains, each of which is represented by a cubic element. The dipole directions of the domains are randomly assigned to simulate the crystallographic nature of ferromagnetic polycrystals. A switching criterion for the domains is specified at the microscopic level. The macroscopic constitutive behavior is obtained by averaging the microscopic/local behavior of each domain. The developed model has been applied to the simulation of a ferromagnetic material. With appropriate material parameters adopted, hysteresis loops of the predicted magnetic induction versus magnetic field and those of the strain versus magnetic field are shown to agree well with experimental observations.展开更多
The present paper studies the coalescence of pore columns in ferroelectric ceramics driven by back and forth domain switching under cyclic electric field. A finite element method that incorporates mass transfer capaci...The present paper studies the coalescence of pore columns in ferroelectric ceramics driven by back and forth domain switching under cyclic electric field. A finite element method that incorporates mass transfer capacity is formulated to simulate the evolution of point defects subjected to the kinetics of pore surface diffusion and domain wall migration. The merge of point defects provides a mechanism for the vacancy agglomeration that leads to the formation of large pores or microcracks.展开更多
The influence of platform-switched abutment on stress distribution within the surrounding bone,fixture,abutment,and screw under various loading conditions were studied.Two 3-D finite element models representative of a...The influence of platform-switched abutment on stress distribution within the surrounding bone,fixture,abutment,and screw under various loading conditions were studied.Two 3-D finite element models representative of an implant-supported metal crown for the mandibular first molar and its surrounding bone were computed.Model A simulated the implant with non-platform-switched abutment and model B was for platform-switched abutment.A load of 100 N was applied vertically and obliquely at the center fossa,the tip of the buccal cusp and the distal fossa,respectively.The results show that the distribution of Von Mises stress in the two models is similar.When platform-switched abutment is used,the maximum Von Mises stress within the surrounding bone is lower;however,this value is higher within the fixture and screw.展开更多
Because its high efficiency, its simple stator and rotor structures, the low cost and high reliability, speed operation combined with robust and low cost construction, the switched reluctance machines have represented...Because its high efficiency, its simple stator and rotor structures, the low cost and high reliability, speed operation combined with robust and low cost construction, the switched reluctance machines have represented. In recent years, an interesting alternative to other machine types has been chosen for traction applications especially starter-generator. Their rotors do not generate significant heat, resulting in easy cooling. Their unidirectional flux and current may generate lower core losses and require a simple converter design. Moreover, the switched reluctance machines are known for their high reliability and capability of operating in four quadrants for a variable speed drive. Despite those merits, switched reluctance machine has not been extensively used until recently because of its problems of torque ripples and noise. Additionally, researchers have faced many difficulties to build a SRM model because it is inherently multivariable. It has strong coupling and especially a high nonlinearity. In this paper, we deal with many modeling methods. Numerical, analytical and intelligent approaches are studied. The important aim in this research is to use static results from FEMM simulation as flux-linkage, co-energy, static torque to form a dynamic model of a switched reluctance machine used next as a starter-generator of a hybrid vehicle.展开更多
The magnetization reversal process of nano-size rectangle-shaped NiFe film elements with different aspect ratios have been investigated under the orthogonally applied magnetic fields by micromagnetic simulation. Diffe...The magnetization reversal process of nano-size rectangle-shaped NiFe film elements with different aspect ratios have been investigated under the orthogonally applied magnetic fields by micromagnetic simulation. Different magnetization reversal modes can appear depending on whether the bias field is applied or not. When there is no bias field, double “C” state is the initial reversal state. However, when there is a bias field, “S” state is the starting mode. The larger the aspect ratio is, the larger the switching field is. But, when the aspect ratio is larger than 3, the increase of the switching field ceases. These results can provide useful information to the application of the patterned NiFe film with rectangular elements.展开更多
The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic fi...The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.展开更多
为解决SONiC(software for open networking in the cloud)交换机操作系统对多模态网络(polymor phic network,PINet)中模态适配及模态管控问题,提出了一个基于P4Runtime的SONiC网元控制通道容器p4runtime-pins,使多模态网元设备可以支...为解决SONiC(software for open networking in the cloud)交换机操作系统对多模态网络(polymor phic network,PINet)中模态适配及模态管控问题,提出了一个基于P4Runtime的SONiC网元控制通道容器p4runtime-pins,使多模态网元设备可以支持多种网络模态流表的配置。p4runtime-pins容器通过gRPC服务模块实现与控制器的连接,使用邻近网元发现算法实现控制器对链路的发现。设计了网元端口更新算法解决了网元设备在实际应用环境中存在的端口变更问题。同时,针对SONiC网元交换机中硬件转发处理单元存在的流表支持性差异问题,设计了内部流表转存和gRPC网元代理功能,实现了不同网络模态流表的部署。实验结果表明,p4runtime-pins容器资源消耗低,仅占用了1.70%的CPU资源和0.45%的内存资源。同时,部署p4runtime-pins容器的SONiC网元设备能够准确地接收并配置控制器下发的流表规则,流表配置延迟仅为0.027~0.037 s。展开更多
大规模电化学储能系统(battery energy storage system,BESS)送出线路发生故障时,受其低电压穿越控制(low voltage ride-through,LVRT)策略的影响,其正序故障分量阻抗特征与传统电源存在较大差异。本文基于BESS相关的技术规定,根据BESS...大规模电化学储能系统(battery energy storage system,BESS)送出线路发生故障时,受其低电压穿越控制(low voltage ride-through,LVRT)策略的影响,其正序故障分量阻抗特征与传统电源存在较大差异。本文基于BESS相关的技术规定,根据BESS故障前后的充放电模式将其工作模式转换方式分为3种,进一步计及BESS的LVRT控制策略,推导出不同工作模式转化方式下其正序故障分量阻抗角的表达式,从而分析了不同影响因素对BESS正序故障分量阻抗角的影响,并据此研究了正序故障分量方向元件在BESS接入场景下的适应性。最后利用Matlab/Simulink仿真平台验证了理论分析的正确性。展开更多
基金Supported by the National Natural Science Foundation of China, Project (NO. 969001405)and the National Key Lab. on ISN
文摘This paper proposes a new high-performance switching element with the new shared-memory queuing policy, which is called blocked-cell shared-memory (BCSM) queuing. As the name means, instead of buffering all cells through them, the BCSM switching elements only buffer the blocked cells at their input ports. Theoretic analysis results under the uniform traffic model prove that BCSM switching elements have better performance than shared-memory switching elements.
文摘In this communication we propose a method to implement an all-optical astable multivibrator using the non-linear material based switches and logic gates. The scheme can operate in real time. The delay time can achieve ps(pico-second). The pulse duration can be made very low and may cross the THz easily by selecting proper material and laser source.
基金The project supported by the National Natural Science Foundation of China(10025209,10132010 90208002)the Research Grants of the Council of the Hong Kong Special Administrative Region,China(HKU7086/02E)the Key Grant Project of the Chinese Ministr
文摘A nonlinear finite element （FE） model based on domain switching was proposed to study the electromechanical behavior of ferroelectric ceramics. The incremental FE formulation was improved to avoid any calculation instability. The problems of mesh sensitivity and convergence, and the efficiency of the proposed nonlinear FE technique have been assessed to illustrate the versatility and potential accuracy of the said technique. The nonlinear electromechanical behavior, such as the hysteresis loops and butterfly curves, of ferroelectric ceramics subjected to both a uniform electric field and a point electric potential has been studied numerically. The results obtained are in good agreement with those of the corresponding theoretical and experimental analyses. Furthermore, the electromechanical coupling fields near （a） the boundary of a circular hole, （b） the boundary of an elliptic hole and （c） the tip of a crack, have been analyzed using the proposed nonlinear finite element method （FEM）. The proposed nonlinear electromechanically coupled FEM is useful for the analysis of domain switching, deformation and fracture of ferroelectric ceramics.
基金The project supported by the National Natural Science Foundation of China (90205030. 10472088, 10425210), the National Basic Research Program of China (2006CB601202) and the State Administration of the Foreign Experts Affairs Through the "111" Project (
文摘A micromechanics-based finite element model for the constitutive behavior of polycrystalline ferromagnets is developed. In the model, the polycrystalline solid is assumed to comprise numerous single crystals with randomly distributed crystallographic orientations, and the single crystals, in turn, consist of ferromagnetic domains, each of which is represented by a cubic element. The dipole directions of the domains are randomly assigned to simulate the crystallographic nature of ferromagnetic polycrystals. A switching criterion for the domains is specified at the microscopic level. The macroscopic constitutive behavior is obtained by averaging the microscopic/local behavior of each domain. The developed model has been applied to the simulation of a ferromagnetic material. With appropriate material parameters adopted, hysteresis loops of the predicted magnetic induction versus magnetic field and those of the strain versus magnetic field are shown to agree well with experimental observations.
基金The project supported by the National Natural Science Foundation of China (10332020 and 10121202)the National 973 Project (2004CB619304)
文摘The present paper studies the coalescence of pore columns in ferroelectric ceramics driven by back and forth domain switching under cyclic electric field. A finite element method that incorporates mass transfer capacity is formulated to simulate the evolution of point defects subjected to the kinetics of pore surface diffusion and domain wall migration. The merge of point defects provides a mechanism for the vacancy agglomeration that leads to the formation of large pores or microcracks.
基金Funded by the National Key Technology R&D Program of China during the 11th Five-year Plan (No.2007BAI18B05)
文摘The influence of platform-switched abutment on stress distribution within the surrounding bone,fixture,abutment,and screw under various loading conditions were studied.Two 3-D finite element models representative of an implant-supported metal crown for the mandibular first molar and its surrounding bone were computed.Model A simulated the implant with non-platform-switched abutment and model B was for platform-switched abutment.A load of 100 N was applied vertically and obliquely at the center fossa,the tip of the buccal cusp and the distal fossa,respectively.The results show that the distribution of Von Mises stress in the two models is similar.When platform-switched abutment is used,the maximum Von Mises stress within the surrounding bone is lower;however,this value is higher within the fixture and screw.
文摘Because its high efficiency, its simple stator and rotor structures, the low cost and high reliability, speed operation combined with robust and low cost construction, the switched reluctance machines have represented. In recent years, an interesting alternative to other machine types has been chosen for traction applications especially starter-generator. Their rotors do not generate significant heat, resulting in easy cooling. Their unidirectional flux and current may generate lower core losses and require a simple converter design. Moreover, the switched reluctance machines are known for their high reliability and capability of operating in four quadrants for a variable speed drive. Despite those merits, switched reluctance machine has not been extensively used until recently because of its problems of torque ripples and noise. Additionally, researchers have faced many difficulties to build a SRM model because it is inherently multivariable. It has strong coupling and especially a high nonlinearity. In this paper, we deal with many modeling methods. Numerical, analytical and intelligent approaches are studied. The important aim in this research is to use static results from FEMM simulation as flux-linkage, co-energy, static torque to form a dynamic model of a switched reluctance machine used next as a starter-generator of a hybrid vehicle.
文摘The magnetization reversal process of nano-size rectangle-shaped NiFe film elements with different aspect ratios have been investigated under the orthogonally applied magnetic fields by micromagnetic simulation. Different magnetization reversal modes can appear depending on whether the bias field is applied or not. When there is no bias field, double “C” state is the initial reversal state. However, when there is a bias field, “S” state is the starting mode. The larger the aspect ratio is, the larger the switching field is. But, when the aspect ratio is larger than 3, the increase of the switching field ceases. These results can provide useful information to the application of the patterned NiFe film with rectangular elements.
文摘The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.
文摘为解决SONiC(software for open networking in the cloud)交换机操作系统对多模态网络(polymor phic network,PINet)中模态适配及模态管控问题,提出了一个基于P4Runtime的SONiC网元控制通道容器p4runtime-pins,使多模态网元设备可以支持多种网络模态流表的配置。p4runtime-pins容器通过gRPC服务模块实现与控制器的连接,使用邻近网元发现算法实现控制器对链路的发现。设计了网元端口更新算法解决了网元设备在实际应用环境中存在的端口变更问题。同时,针对SONiC网元交换机中硬件转发处理单元存在的流表支持性差异问题,设计了内部流表转存和gRPC网元代理功能,实现了不同网络模态流表的部署。实验结果表明,p4runtime-pins容器资源消耗低,仅占用了1.70%的CPU资源和0.45%的内存资源。同时,部署p4runtime-pins容器的SONiC网元设备能够准确地接收并配置控制器下发的流表规则,流表配置延迟仅为0.027~0.037 s。
文摘大规模电化学储能系统(battery energy storage system,BESS)送出线路发生故障时,受其低电压穿越控制(low voltage ride-through,LVRT)策略的影响,其正序故障分量阻抗特征与传统电源存在较大差异。本文基于BESS相关的技术规定,根据BESS故障前后的充放电模式将其工作模式转换方式分为3种,进一步计及BESS的LVRT控制策略,推导出不同工作模式转化方式下其正序故障分量阻抗角的表达式,从而分析了不同影响因素对BESS正序故障分量阻抗角的影响,并据此研究了正序故障分量方向元件在BESS接入场景下的适应性。最后利用Matlab/Simulink仿真平台验证了理论分析的正确性。
