In order to analysis the distribution characteristics of in-bore magnetic field for C-shaped armature electromagnetic railgun, a computational model considering dynamic contact pressure is established. By solving the ...In order to analysis the distribution characteristics of in-bore magnetic field for C-shaped armature electromagnetic railgun, a computational model considering dynamic contact pressure is established. By solving the dynamic equation, the in-bore motion characteristics of the armature are obtained. The distribution of current in the rail and armature is analyzed based on the magnetic diffusion equation and Ampere’s law. On this basis, three simulation models are proposed, which correspond to static state,motion state and motion state considering the velocity skin effect. The magnetic field of the investigated points along the central axes of the armature front end are obtained. The results show that, in static state,the peak magnetic flux density of each investigated point is greater than the other two states. Velocity skin effect leads to a decrease in peak magnetic flux density. The change of motion state has little influence on the peak magnetic flux density of the investigated point that far away from the armature. The calculated results can be used in the electromagnetic shielding design of intelligent ammunition.展开更多
The design of solid armature of railgun should take full account of its operating conditions and material properties because the armature is subjected to dynamic loading conditions and experiences a complicated electr...The design of solid armature of railgun should take full account of its operating conditions and material properties because the armature is subjected to dynamic loading conditions and experiences a complicated electrical,thermal and mechanical process in the interior ballistic cycle.In this paper present,we first introduced a multi-physical field model of railgun,followed by several examples to investigate the launching process.Especially,we used the explicit finite element method,in which material nonlinearity and geometric nonlinearity were accounted,to investigate the deform behaviors of solid armature.The results show that the dynamic mechanical process of armature is dependent on the armature geometry,material and exciting electric current.By the numerical simulation,the understanding of the fracture mechanism of solid armature was deepened.展开更多
The armature is an important part affecting the energy conversion efficiency of a reluctance accelerator.In this paper,six kinds of soft magnetic materials are chosen and four structures are designed for the armature....The armature is an important part affecting the energy conversion efficiency of a reluctance accelerator.In this paper,six kinds of soft magnetic materials are chosen and four structures are designed for the armature.At first,the circuit and magnetic force are theoretically analyzed.Then the armatures with different materials and structures are used in the simulation,and the performances are compared and analyzed.At last,the experiment verifies the theory analysis and simulation design.It is concluded that the saturation flux density and conductivity of the material are the key factors affecting the armature force,and the optimization of armature structure can effectively restrain the eddy current,reduce negative force and improve efficiency.Compared with cutting slits in solid armatures,laminating the sheets radially can reduce the eddy current more efficiently.Although slitting can prevent the eddy current to a certain extent,meanwhile,it will decrease the magnetic force because of the losing of magnetized volume and the surface area.Hence,choosing the high saturation flux density material and making out the armature with radially_laminated sheets will improve the efficiency of the reluctance accelerator.In this paper,the silicon steel radially_laminated armature is a better choice for the armature design of the reluctance accelerator.展开更多
The authors have invented the superior wind power unit, which is composed of the tandem wind rotors and the double rotational armature type generator without the traditional stator. The large-sized front wind rotor an...The authors have invented the superior wind power unit, which is composed of the tandem wind rotors and the double rotational armature type generator without the traditional stator. The large-sized front wind rotor and the small-sized rear wind rotor drive, as for the upwind type, the inner and the outer rotational armatures, respectively, in keeping the rotational torque counter-balanced between both wind rotors/armatures. The unique rotational behaviors of the tandem wind rotors and the fundamental performances of the unit have been discussed at the previous paper. Continuously, this paper investigates experimentally and numerically the flow condition around the wind rotors to know the flow interactions between the front and the rear wind rotors, and optimizes the blade profile in the front wind rotor. The front blade should work fruitfully at the larger radius and had better not work at the smaller radius for giving plenty of wind energy to the rear wind rotor, taking account of the flow interaction between both wind rotors.展开更多
We present a novel armature structure for 3D articulated shapes, called SBall short for skeletal balls, which includes two parts: a one-dimensional skeleton and incident balls. Our algorithm mainly focuses on constru...We present a novel armature structure for 3D articulated shapes, called SBall short for skeletal balls, which includes two parts: a one-dimensional skeleton and incident balls. Our algorithm mainly focuses on constructing the armature structure. This structure is based on an approximation skeleton which is homotopy equivalent to the shape. Each ball in the structure connects a skeletal joint and an interior region of the shape. The boundary vertices on the shape surface are attached onto the SBall using the power diagram of the ball set. A bilateral O^tering algorithm and a variational segmentation algorithm are proposed to enhance the quality of SBall. Finally, applications of this structure are discussed.展开更多
A measurement system has been developed based on high-precision printed probes in printed circuit board (PCB) and steep rising-time probe adapters, which can be applied to study the expansion uniformity of armature ...A measurement system has been developed based on high-precision printed probes in printed circuit board (PCB) and steep rising-time probe adapters, which can be applied to study the expansion uniformity of armature in a helical magnetic flux compression generator (HFCG). The influences of wall thickness and initiation position on the expansion uniformity of armature in HFCG were experimentally investigated. The results show that the armature with thinner wall thickness will easily rupture due to the high pressure of detonation products inside, the armature with larger wall thickness will easily crack due to the tensile stress on the outer surface of the wall, the influence of the end effect on the expansion uniformity can be ignored if the distance between the first group of probe and the initiation point is more than 3 times the armature diameter.展开更多
Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system ...Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system with electromagnetic system will cause EMR malfunction. The nonlinear dynamics model of armature systems was studied by considering electro- magnetic attraction force and opposite mechanical force in this paper. Angular displacements of armature under different sinu- soidal vibration conditions are solved in order to obtain the failure mode result from armature system. Vibration tests showed the presented analyzing method is suitable for EMR. The conclusions are instructive for increasing vibration resistance of armature systems of EMR, and are significant for reliability design of switch apparatus.展开更多
The paper develops accurate analytical subdomain models for predicting the magnetic and armature reaction fields in fault-tolerant flux-switching permanent-magnet machines.The entire region is divided into five subdom...The paper develops accurate analytical subdomain models for predicting the magnetic and armature reaction fields in fault-tolerant flux-switching permanent-magnet machines.The entire region is divided into five subdomains,followed by rotor slots,air-gap,stator slots,PM,and external air-gap imported to account for flux leakage.The coil turns and the remanence of magnets are adjusted by keeping the magnetic and electrical loading on the motor constant.The distance between the centers of two adjacent stator slots varies due to the introduction of faulttolerant teeth.According to the variable separation method,the general solution expression of each region can be determined by solving the partial differential systems of equations.The magnetic field distributions of subdomains are obtained by applying the continuity conditions between adjacent regions.Some analytical field expressions are represented as new forms under armature reaction field condition compared to those under no-load condition.Based on the developed analytical models,the flux density distribution and the electromagnetic performance can be calculated under no-load or armature reaction field condition separately.The finite element analysis is carried out to verify the validity of the proposed analytical model.展开更多
定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效...定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效磁网络模型准确计算槽内微小单元储存的磁场能量,进而计算定子槽漏感。基于所提出的方法,进一步研究定子结构参数以及极槽配合对YASA电机定子槽漏感的影响规律。有限元仿真和实验结果表明,该文所提出的YASA电机定子槽漏感计算方法的可行性和准确性。展开更多
新型电力系统的惯性低,虚拟直流电机控制可以加强系统惯性和阻尼。多储能变换器应该考虑荷电状态(State of charge,SOC)均衡问题,提高系统稳定性。针对虚拟直流电机控制的多储能SOC均衡问题,利用直流电机机端电压和电枢电流的下垂特性,...新型电力系统的惯性低,虚拟直流电机控制可以加强系统惯性和阻尼。多储能变换器应该考虑荷电状态(State of charge,SOC)均衡问题,提高系统稳定性。针对虚拟直流电机控制的多储能SOC均衡问题,利用直流电机机端电压和电枢电流的下垂特性,提出引入SOC离差及变均衡系数的变电枢电阻控制;针对下垂引起的电压偏移问题,采用虚拟直流电机转速补偿,用母线电容瞬时功率替代传统虚拟直流电机控制中电压PI控制,给定系统功率需求,减少比例积分环节个数。以两台蓄电池为例,在Simulink中进行仿真,并与参考文献的变电枢电阻函数对比可知,所提控制策略可抑制直流母线电压跌落,调节SOC均衡过程,提高其均衡速度和精度。展开更多
为了满足定子无磁轭分块电枢(yokeless and segmented armature,YASA)轴向磁通永磁电机作为车用牵引电机时对输出转矩高平稳性的要求,提出一种基于永磁体径向均匀分段、分组同向偏移的方法来抑制YASA电机的齿槽转矩,以降低转矩脉动。应...为了满足定子无磁轭分块电枢(yokeless and segmented armature,YASA)轴向磁通永磁电机作为车用牵引电机时对输出转矩高平稳性的要求,提出一种基于永磁体径向均匀分段、分组同向偏移的方法来抑制YASA电机的齿槽转矩,以降低转矩脉动。应用三维有限元分析,分别研究了3种不同的永磁体分段方案对齿槽转矩的削弱效果,确定了磁极的最优偏转角度及其对电机综合性能的影响。仿真结果验证了该方法的可行性。YASA电机的齿槽转矩降低了92.62%,额定工况下转矩脉动下降了72.02%,永磁体涡流损耗降低91.28%,同时输出转矩下降不超过5.34%,提高了YASA电机的综合性能。展开更多
It has been reported that C-type lectins(CTLs),which are pattern recognition receptors of the insect innate immunity response,may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity i...It has been reported that C-type lectins(CTLs),which are pattern recognition receptors of the insect innate immunity response,may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity in insects.However,to date,which CTLs affect larval susceptibility to Bt in Spodoptera exigua is not clear.In this study,33 CTL genes were identified from S.exigua.Based on the number of carbohydrate-recognition domains(CRDs)and the domain architectures,they were classified into three groups:(1)nineteen CTL-S(single-CRD),(2)eight immulectin(dual-CRD)and(3)six CTL-X(CRD with other domains).RT-qPCR analysis revealed that expression levels of SeCTL-S15,IML-4 and CTL-X6 were upregulated after challenge with Bt and Cry1Ab.Tissue and developmental stage expression analysis showed that only SeCTL-S15 was mainly expressed in the midgut and larva,respectively.Knockdown of SeCTL-S15 significantly increased Bt susceptibility,as indicated by reduced survival and larval weight.These results suggest that CTL-S15 might play a vital role in the low susceptibility of larvae to Bt in S.exigua.Our results provide new insights into CTL function in insects.展开更多
The feedback spring rod of the armature assembly is cancelled in the double redundance double nozzle flapper valve(DRDNFV),and the difficulty of valve core displacement control is increased.Therefore,this paper intend...The feedback spring rod of the armature assembly is cancelled in the double redundance double nozzle flapper valve(DRDNFV),and the difficulty of valve core displacement control is increased.Therefore,this paper intends to study the static characteristic of DRDNFV through the AMESet and AMESim simulation.It is explored under the circumstance of the fixed orifices being clogged and experimentally verified on the test bench.The results show that the pressure gain increases and the flow gain decreases with the increasing clogged degree of the fixed orifices on both sides.The zero bias increases synchronously with the increasing clogged degree of the unilateral fixed orifice.The experimental results are basically consistent with the theoretical curves and the theoretical correctness of the simulation model is effectively verified.The results can provide the theoretical reference for design,debugging,maintenance and fault diagnosis of DRDNFV.展开更多
基金supported by the Key Basic Research Projects of Basic Strengthening Plan under Grants 2017-JCJQ-ZD-004
文摘In order to analysis the distribution characteristics of in-bore magnetic field for C-shaped armature electromagnetic railgun, a computational model considering dynamic contact pressure is established. By solving the dynamic equation, the in-bore motion characteristics of the armature are obtained. The distribution of current in the rail and armature is analyzed based on the magnetic diffusion equation and Ampere’s law. On this basis, three simulation models are proposed, which correspond to static state,motion state and motion state considering the velocity skin effect. The magnetic field of the investigated points along the central axes of the armature front end are obtained. The results show that, in static state,the peak magnetic flux density of each investigated point is greater than the other two states. Velocity skin effect leads to a decrease in peak magnetic flux density. The change of motion state has little influence on the peak magnetic flux density of the investigated point that far away from the armature. The calculated results can be used in the electromagnetic shielding design of intelligent ammunition.
文摘The design of solid armature of railgun should take full account of its operating conditions and material properties because the armature is subjected to dynamic loading conditions and experiences a complicated electrical,thermal and mechanical process in the interior ballistic cycle.In this paper present,we first introduced a multi-physical field model of railgun,followed by several examples to investigate the launching process.Especially,we used the explicit finite element method,in which material nonlinearity and geometric nonlinearity were accounted,to investigate the deform behaviors of solid armature.The results show that the dynamic mechanical process of armature is dependent on the armature geometry,material and exciting electric current.By the numerical simulation,the understanding of the fracture mechanism of solid armature was deepened.
基金supported in part by the Fundamental Research Funds for the Central Universities,China[grant number 2682020GF03]in part by the Foundation of Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle,Ministry of Education,China.
文摘The armature is an important part affecting the energy conversion efficiency of a reluctance accelerator.In this paper,six kinds of soft magnetic materials are chosen and four structures are designed for the armature.At first,the circuit and magnetic force are theoretically analyzed.Then the armatures with different materials and structures are used in the simulation,and the performances are compared and analyzed.At last,the experiment verifies the theory analysis and simulation design.It is concluded that the saturation flux density and conductivity of the material are the key factors affecting the armature force,and the optimization of armature structure can effectively restrain the eddy current,reduce negative force and improve efficiency.Compared with cutting slits in solid armatures,laminating the sheets radially can reduce the eddy current more efficiently.Although slitting can prevent the eddy current to a certain extent,meanwhile,it will decrease the magnetic force because of the losing of magnetized volume and the surface area.Hence,choosing the high saturation flux density material and making out the armature with radially_laminated sheets will improve the efficiency of the reluctance accelerator.In this paper,the silicon steel radially_laminated armature is a better choice for the armature design of the reluctance accelerator.
文摘The authors have invented the superior wind power unit, which is composed of the tandem wind rotors and the double rotational armature type generator without the traditional stator. The large-sized front wind rotor and the small-sized rear wind rotor drive, as for the upwind type, the inner and the outer rotational armatures, respectively, in keeping the rotational torque counter-balanced between both wind rotors/armatures. The unique rotational behaviors of the tandem wind rotors and the fundamental performances of the unit have been discussed at the previous paper. Continuously, this paper investigates experimentally and numerically the flow condition around the wind rotors to know the flow interactions between the front and the rear wind rotors, and optimizes the blade profile in the front wind rotor. The front blade should work fruitfully at the larger radius and had better not work at the smaller radius for giving plenty of wind energy to the rear wind rotor, taking account of the flow interaction between both wind rotors.
基金Supported by the National Natural Science Foundation of China(61202278 and 61222206)the Zhejiang Natural Science Foundation of China(Y1111101)
文摘We present a novel armature structure for 3D articulated shapes, called SBall short for skeletal balls, which includes two parts: a one-dimensional skeleton and incident balls. Our algorithm mainly focuses on constructing the armature structure. This structure is based on an approximation skeleton which is homotopy equivalent to the shape. Each ball in the structure connects a skeletal joint and an interior region of the shape. The boundary vertices on the shape surface are attached onto the SBall using the power diagram of the ball set. A bilateral O^tering algorithm and a variational segmentation algorithm are proposed to enhance the quality of SBall. Finally, applications of this structure are discussed.
基金Sponsored by the Ministerial Level Advanced Research Foundation (40407010305)
文摘A measurement system has been developed based on high-precision printed probes in printed circuit board (PCB) and steep rising-time probe adapters, which can be applied to study the expansion uniformity of armature in a helical magnetic flux compression generator (HFCG). The influences of wall thickness and initiation position on the expansion uniformity of armature in HFCG were experimentally investigated. The results show that the armature with thinner wall thickness will easily rupture due to the high pressure of detonation products inside, the armature with larger wall thickness will easily crack due to the tensile stress on the outer surface of the wall, the influence of the end effect on the expansion uniformity can be ignored if the distance between the first group of probe and the initiation point is more than 3 times the armature diameter.
基金Project (No. FEBQ24409102) supported by the Space Technology Innovation Fund, China
文摘Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system with electromagnetic system will cause EMR malfunction. The nonlinear dynamics model of armature systems was studied by considering electro- magnetic attraction force and opposite mechanical force in this paper. Angular displacements of armature under different sinu- soidal vibration conditions are solved in order to obtain the failure mode result from armature system. Vibration tests showed the presented analyzing method is suitable for EMR. The conclusions are instructive for increasing vibration resistance of armature systems of EMR, and are significant for reliability design of switch apparatus.
基金supported in part by the National Natural Science Foundation of China under Grants 51991383 and 52025073。
文摘The paper develops accurate analytical subdomain models for predicting the magnetic and armature reaction fields in fault-tolerant flux-switching permanent-magnet machines.The entire region is divided into five subdomains,followed by rotor slots,air-gap,stator slots,PM,and external air-gap imported to account for flux leakage.The coil turns and the remanence of magnets are adjusted by keeping the magnetic and electrical loading on the motor constant.The distance between the centers of two adjacent stator slots varies due to the introduction of faulttolerant teeth.According to the variable separation method,the general solution expression of each region can be determined by solving the partial differential systems of equations.The magnetic field distributions of subdomains are obtained by applying the continuity conditions between adjacent regions.Some analytical field expressions are represented as new forms under armature reaction field condition compared to those under no-load condition.Based on the developed analytical models,the flux density distribution and the electromagnetic performance can be calculated under no-load or armature reaction field condition separately.The finite element analysis is carried out to verify the validity of the proposed analytical model.
文摘定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效磁网络模型准确计算槽内微小单元储存的磁场能量,进而计算定子槽漏感。基于所提出的方法,进一步研究定子结构参数以及极槽配合对YASA电机定子槽漏感的影响规律。有限元仿真和实验结果表明,该文所提出的YASA电机定子槽漏感计算方法的可行性和准确性。
文摘新型电力系统的惯性低,虚拟直流电机控制可以加强系统惯性和阻尼。多储能变换器应该考虑荷电状态(State of charge,SOC)均衡问题,提高系统稳定性。针对虚拟直流电机控制的多储能SOC均衡问题,利用直流电机机端电压和电枢电流的下垂特性,提出引入SOC离差及变均衡系数的变电枢电阻控制;针对下垂引起的电压偏移问题,采用虚拟直流电机转速补偿,用母线电容瞬时功率替代传统虚拟直流电机控制中电压PI控制,给定系统功率需求,减少比例积分环节个数。以两台蓄电池为例,在Simulink中进行仿真,并与参考文献的变电枢电阻函数对比可知,所提控制策略可抑制直流母线电压跌落,调节SOC均衡过程,提高其均衡速度和精度。
文摘为了满足定子无磁轭分块电枢(yokeless and segmented armature,YASA)轴向磁通永磁电机作为车用牵引电机时对输出转矩高平稳性的要求,提出一种基于永磁体径向均匀分段、分组同向偏移的方法来抑制YASA电机的齿槽转矩,以降低转矩脉动。应用三维有限元分析,分别研究了3种不同的永磁体分段方案对齿槽转矩的削弱效果,确定了磁极的最优偏转角度及其对电机综合性能的影响。仿真结果验证了该方法的可行性。YASA电机的齿槽转矩降低了92.62%,额定工况下转矩脉动下降了72.02%,永磁体涡流损耗降低91.28%,同时输出转矩下降不超过5.34%,提高了YASA电机的综合性能。
基金supported by the National Key Research and Development Program of China(2022YFD1401200)the National Natural Science Foundation of China(32172397).
文摘It has been reported that C-type lectins(CTLs),which are pattern recognition receptors of the insect innate immunity response,may compete with Cry toxin for the receptor alkaline phosphatase to decrease its toxicity in insects.However,to date,which CTLs affect larval susceptibility to Bt in Spodoptera exigua is not clear.In this study,33 CTL genes were identified from S.exigua.Based on the number of carbohydrate-recognition domains(CRDs)and the domain architectures,they were classified into three groups:(1)nineteen CTL-S(single-CRD),(2)eight immulectin(dual-CRD)and(3)six CTL-X(CRD with other domains).RT-qPCR analysis revealed that expression levels of SeCTL-S15,IML-4 and CTL-X6 were upregulated after challenge with Bt and Cry1Ab.Tissue and developmental stage expression analysis showed that only SeCTL-S15 was mainly expressed in the midgut and larva,respectively.Knockdown of SeCTL-S15 significantly increased Bt susceptibility,as indicated by reduced survival and larval weight.These results suggest that CTL-S15 might play a vital role in the low susceptibility of larvae to Bt in S.exigua.Our results provide new insights into CTL function in insects.
基金Supported by the National Natural Science Foundation of China(52075468)the General Project of Natural Science Foundation of Hebei Prov-ince(E2020203052)+1 种基金the Open Fund Project of Shaanxi Provincial Key Laboratory of Hydraulic Technology(YYJS2022KF14)the BasicInnovation Research Cultivation Project of Yanshan University(2021LGZD003)。
文摘The feedback spring rod of the armature assembly is cancelled in the double redundance double nozzle flapper valve(DRDNFV),and the difficulty of valve core displacement control is increased.Therefore,this paper intends to study the static characteristic of DRDNFV through the AMESet and AMESim simulation.It is explored under the circumstance of the fixed orifices being clogged and experimentally verified on the test bench.The results show that the pressure gain increases and the flow gain decreases with the increasing clogged degree of the fixed orifices on both sides.The zero bias increases synchronously with the increasing clogged degree of the unilateral fixed orifice.The experimental results are basically consistent with the theoretical curves and the theoretical correctness of the simulation model is effectively verified.The results can provide the theoretical reference for design,debugging,maintenance and fault diagnosis of DRDNFV.