From the principles of electromechanical energy conversion and electromagnetic torque generation, our study evaluatedthe mathematical model of the electromagnetic torque and the vector control method of motors. An ana...From the principles of electromechanical energy conversion and electromagnetic torque generation, our study evaluatedthe mathematical model of the electromagnetic torque and the vector control method of motors. An analysis of motor typesindicates that the electromechanical energy conversion component is interchangeable. Three distinct types of motor structures,namely DC, induction, and synchronous, are possible, all three being commonly used in pure electric vehicles. For each motortype, simulation models were developed using Modelica, a modeling language for object-oriented multi-domain physicalsystem. A test model of each motor type was configured in the MWorks simulation platform. With a representative motor,specifically the permanent-magnet DC motor, the asynchronous induction motor, and the permanent-magnet synchronousmotor, mechanical properties were simulated and analyzed. The simulation results show that the characteristics of each motormodel are consistent with the theoretical and engineering performance of the representative motor. Therefore, modeling,motor control, and performance testing of a unified multi-pole-field motor, which is used in pure electric vehicles, have beenachieved.展开更多
The aim of this study was to explore the utility of a visualization phantom for building a real-time temperature field distribution model of the prostate created by the application of special data encryption(SDE) mult...The aim of this study was to explore the utility of a visualization phantom for building a real-time temperature field distribution model of the prostate created by the application of special data encryption(SDE) multi-pole radiofrequency(RF) ablation.We prepared phantoms(phantom group) using acrylamide as the raw material and egg-white as a color developing reagent.The prostate specimens of male adult dogs were fixed in this phantom to create a prostate phantom(prostate group).The SDE multi-pole RF electrode was inserted into the two groups for RF ablation,and the temperature changes at relevant points in space were detected.We set the x-axis as the left and right direction,the y-axis as the fore and aft direction,and the z-axis as the insertion direction of the RF electrode.After this process,the effect of RF ablation on the appearance of each of the two groups was observed.Using temperature measurements taken during the operation,a three-dimensional(3D) surface model of temperature was constructed by drawing the boundary areas of different temperatures on the maximum x-z plane of the two groups of ablation lesions,with y equivalent to 0.Further comparison of the temperature-time change curves of four space points were made by setting y equivalent to 0,z equivalent to 0.5,and x equivalent to 0,0.25,0.5 and 0.75.White solid lesions with a diameter of approximately 12 mm could be found in both groups after RF ablation.During the ablation of the phantom group,the temperature ascended faster in a zone 1 cm from the needlepoint to the needle body,and 0.5 cm about the radiofrequency needle.The time-property result of the x-z plane with y equivalent to 0 showed that the boundary areas of the two groups were closer at 50 and 60°C,but the difference between the two groups at 70°C in the high temperature zone was relatively large.The 3D temperature surface model further proved that the 3D temperature outline at 60°C was in better concordance with the actual effect of RF ablation in the prostate tissue.In the comparison of temperature-time changing curves of the two groups at the four space points,despite there being a significant difference in the changing process(P=0.0001),there was no significant statistical difference in the final temperature of the two groups(P>0.05).The results of this work indicated that ablation appearance was in good agreement with in-vitro biologic tissues and that the RF temperature field distribution can be obtained by using a visualization phantom.In particular,the shape of the isothermal line at 60°C was close to the actual ablation lesion.These results may serve as a valuable reference to future clinical trials.展开更多
利用精确解析模型生成的数据可辅助构建数值仿真样本集,为代理模型提供高质量训练数据,从而在降低计算成本的同时提升多目标优化效率。但现有解析建模常受电机拓扑约束,适用范围有限。为此,该文提出一种基于几何相似性迁移学习的电机代...利用精确解析模型生成的数据可辅助构建数值仿真样本集,为代理模型提供高质量训练数据,从而在降低计算成本的同时提升多目标优化效率。但现有解析建模常受电机拓扑约束,适用范围有限。为此,该文提出一种基于几何相似性迁移学习的电机代理模型优化方法。首先,依据物理结构之间的几何相似性构建易于精确解析化的相似电机;随后,建立相似电机设计变量-优化目标的解析映射模型并开展灵敏度分析;进而,对设计变量分层,将变量空间划分为高-低灵敏度子空间,以提高相似电机迁移结果与原型优化结果的一致性。少变量的高灵敏度参数空间通过原电机有限元分析(finite element analysis,FEA)数据建立常规代理模型进行优化,而多变量的低灵敏度参数空间则基于充足的相似电机解析数据并结合少量原型电机FEA数据,利用迁移学习训练多重保真代理模型完成最终优化。所提方法突破了精确解析模型拓扑限制,降低了结构复杂电机解析建模难度,并通过分层优化策略结合多重保真迁移显著提升高维优化效率,在保证精度前提下大幅减少计算量。该方法已用于内置式交替极永磁游标电机多目标优化,样机试验验证了有效性。展开更多
文摘From the principles of electromechanical energy conversion and electromagnetic torque generation, our study evaluatedthe mathematical model of the electromagnetic torque and the vector control method of motors. An analysis of motor typesindicates that the electromechanical energy conversion component is interchangeable. Three distinct types of motor structures,namely DC, induction, and synchronous, are possible, all three being commonly used in pure electric vehicles. For each motortype, simulation models were developed using Modelica, a modeling language for object-oriented multi-domain physicalsystem. A test model of each motor type was configured in the MWorks simulation platform. With a representative motor,specifically the permanent-magnet DC motor, the asynchronous induction motor, and the permanent-magnet synchronousmotor, mechanical properties were simulated and analyzed. The simulation results show that the characteristics of each motormodel are consistent with the theoretical and engineering performance of the representative motor. Therefore, modeling,motor control, and performance testing of a unified multi-pole-field motor, which is used in pure electric vehicles, have beenachieved.
文摘The aim of this study was to explore the utility of a visualization phantom for building a real-time temperature field distribution model of the prostate created by the application of special data encryption(SDE) multi-pole radiofrequency(RF) ablation.We prepared phantoms(phantom group) using acrylamide as the raw material and egg-white as a color developing reagent.The prostate specimens of male adult dogs were fixed in this phantom to create a prostate phantom(prostate group).The SDE multi-pole RF electrode was inserted into the two groups for RF ablation,and the temperature changes at relevant points in space were detected.We set the x-axis as the left and right direction,the y-axis as the fore and aft direction,and the z-axis as the insertion direction of the RF electrode.After this process,the effect of RF ablation on the appearance of each of the two groups was observed.Using temperature measurements taken during the operation,a three-dimensional(3D) surface model of temperature was constructed by drawing the boundary areas of different temperatures on the maximum x-z plane of the two groups of ablation lesions,with y equivalent to 0.Further comparison of the temperature-time change curves of four space points were made by setting y equivalent to 0,z equivalent to 0.5,and x equivalent to 0,0.25,0.5 and 0.75.White solid lesions with a diameter of approximately 12 mm could be found in both groups after RF ablation.During the ablation of the phantom group,the temperature ascended faster in a zone 1 cm from the needlepoint to the needle body,and 0.5 cm about the radiofrequency needle.The time-property result of the x-z plane with y equivalent to 0 showed that the boundary areas of the two groups were closer at 50 and 60°C,but the difference between the two groups at 70°C in the high temperature zone was relatively large.The 3D temperature surface model further proved that the 3D temperature outline at 60°C was in better concordance with the actual effect of RF ablation in the prostate tissue.In the comparison of temperature-time changing curves of the two groups at the four space points,despite there being a significant difference in the changing process(P=0.0001),there was no significant statistical difference in the final temperature of the two groups(P>0.05).The results of this work indicated that ablation appearance was in good agreement with in-vitro biologic tissues and that the RF temperature field distribution can be obtained by using a visualization phantom.In particular,the shape of the isothermal line at 60°C was close to the actual ablation lesion.These results may serve as a valuable reference to future clinical trials.
文摘利用精确解析模型生成的数据可辅助构建数值仿真样本集,为代理模型提供高质量训练数据,从而在降低计算成本的同时提升多目标优化效率。但现有解析建模常受电机拓扑约束,适用范围有限。为此,该文提出一种基于几何相似性迁移学习的电机代理模型优化方法。首先,依据物理结构之间的几何相似性构建易于精确解析化的相似电机;随后,建立相似电机设计变量-优化目标的解析映射模型并开展灵敏度分析;进而,对设计变量分层,将变量空间划分为高-低灵敏度子空间,以提高相似电机迁移结果与原型优化结果的一致性。少变量的高灵敏度参数空间通过原电机有限元分析(finite element analysis,FEA)数据建立常规代理模型进行优化,而多变量的低灵敏度参数空间则基于充足的相似电机解析数据并结合少量原型电机FEA数据,利用迁移学习训练多重保真代理模型完成最终优化。所提方法突破了精确解析模型拓扑限制,降低了结构复杂电机解析建模难度,并通过分层优化策略结合多重保真迁移显著提升高维优化效率,在保证精度前提下大幅减少计算量。该方法已用于内置式交替极永磁游标电机多目标优化,样机试验验证了有效性。
