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An Operator-based Nonlinear Vibration Control System Using a Flexible Arm with Shape Memory Alloy
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作者 Hiroki Matsumori Ming-Cong Deng Yuichi Noge 《国际自动化与计算杂志:英文版》 EI CSCD 2020年第1期139-150,共12页
In the past,arms used in the fields of industry and robotics have been designed not to vibrate by increasing their mass and stiffness.The weight of arms has tended to be reduced to improve speed of operation,and decre... In the past,arms used in the fields of industry and robotics have been designed not to vibrate by increasing their mass and stiffness.The weight of arms has tended to be reduced to improve speed of operation,and decrease the cost of their production.Since the weight saving makes the arms lose their stiffness and therefore vibrate more easily,the vibration suppression control is needed for realizing the above purpose.Incidentally,the use of various smart materials in actuators has grown.In particular,a shape memory alloy(SMA)is applied widely and has several advantages:light weight,large displacement by temperature change,and large force to mass ratio.However,the SMA actuators possess hysteresis nonlinearity between their own temperature and displacement obtained by the temperature.The hysteretic behavior of the SMA actuators affects their control performance.In previous research,an operator-based control system including a hysteresis compensator has been proposed.The vibration of a flexible arm is dealt with as the controlled object;one end of the arm is clamped and the other end is free.The effectiveness of the hysteresis compensator has been confirmed by simulations and experiments.Nevertheless,the feedback signal of the previous designed system has increased exponentially.It is difficult to use the system in the long-term because of the phenomenon.Additionally,the SMA actuator generates and radiates heat because electric current passing through the SMA actuator provides heat,and strain on the SMA actuator is generated.With long-time use of the SMA actuator,the environmental temperature around the SMA actuator varies through radiation of the heat.There exists a risk that the ambient temperature change dealt with as disturbance affects the temperature and strain of the SMA actuator.In this research,a design method of the operator-based control system is proposed considering the long-term use of the system.In the method,the hysteresis characteristics of the SMA actuator and the temperature change around the actua 展开更多
关键词 Operator theory nonlinear control STABILITY right coprime factorization shape memory alloy hysteresis characteristics
Bifurcation and chaos characteristics of hysteresis vibration system of giant magnetostrictive actuator
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作者 闫洪波 高鸿 +3 位作者 杨高炜 郝宏波 牛禹 刘霈 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第2期165-176,共12页
Chaotic motion and quasi-periodic motion are two common forms of instability in the giant magnetostrictive actuator(GMA).Therefore,in the present study we intend to investigate the influences of the system damping coe... Chaotic motion and quasi-periodic motion are two common forms of instability in the giant magnetostrictive actuator(GMA).Therefore,in the present study we intend to investigate the influences of the system damping coefficient,system stiffness coefficient,disc spring cubic stiffness factor,and the excitation force and frequency on the output stability and the hysteresis vibration of the GMA.In this regard,the nonlinear piezomagnetic equation,Jiles-Atherton hysteresis model,quadratic domain rotation model,and the GMA structural dynamics are used to establish the mathematical model of the hysteresis vibration system of the GMA.Moreover,the multi-scale method and the singularity theory are used to determine the co-dimensional two-bifurcation characteristics of the system.Then,the output response of the system is simulated to determine the variation range of each parameter when chaos is imposed.Finally,the fourth-order Runge-Kutta method is used to obtain the time domain waveform,phase portrait and Poincarémapping diagrams of the system.Subsequently,the obtained three graphs are analyzed.The obtained results show that when the system output is stable,the variation range of each parameter can be determined.Moreover,the stability interval of system damping coefficient,system stiffness coefficient,and the coefficient of the cubic stiffness term of the disc spring are obtained.Furthermore,the stability interval of the exciting force and the excitation frequency are determined. 展开更多
关键词 giant magnetostrictive actuator(GMA) nonlinear hysteresis BIFURCATION CHAOS
背压变化速率对带支板流道内流场的影响 预览
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作者 田亮 刘宏宝 +2 位作者 郭赛男 王恩宇 段润泽 《燃烧科学与技术》 CAS CSCD 北大核心 2020年第1期1-9,共9页
为了进一步了解迟滞现象的机理,利用一个带有支板的矩形截面流道开展了动态反压特性的冷态数值仿真研究,分析了背压变化速率对流场结构的影响规律,捕获了由此引发的流动迟滞.研究结果表明,相较于稳态流动而言,在背压动态变化的条件下流... 为了进一步了解迟滞现象的机理,利用一个带有支板的矩形截面流道开展了动态反压特性的冷态数值仿真研究,分析了背压变化速率对流场结构的影响规律,捕获了由此引发的流动迟滞.研究结果表明,相较于稳态流动而言,在背压动态变化的条件下流场会出现明显的滞后性,背压变化速率越快滞后性越强.在固定的背压上升速率条件下,压力抬升起始位置处于匀加速运动状态,加速度与背压变化速率呈幂函数关系,在背压升高到最大值后的稳定过程中,压力抬升起始位置向上游减速运动,直至停止.在达到最大压比后的背压下降过程中,压力抬升起始位置仍然会向上游继续移动一段距离,这时若压力抬升起始位置移动到支板前缘上游,则支板前缘上游形成的激波串会稳定在支板前缘;若压力抬升起始位置未移动到支板前缘上游,则其变化路径仍与上升过程不重合,出现迟滞现象. 展开更多
关键词 超燃冲压发动机 迟滞 支板 背压 动态变化
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我国半导体显示产业财政补贴效应及研发效率研究 预览
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作者 张振华 《工业技术经济》 CSSCI 北大核心 2020年第2期151-160,共10页
本文对我国半导体显示产业财政补贴效应和研发效率进行研究,分析了财政补贴对企业自主研发投入的诱导效应以及研发投入与研发产出之间的关系,探讨了显示面板集成企业和上游企业财政补贴对自主研发投入诱导效应的异质性和研发效率的异质... 本文对我国半导体显示产业财政补贴效应和研发效率进行研究,分析了财政补贴对企业自主研发投入的诱导效应以及研发投入与研发产出之间的关系,探讨了显示面板集成企业和上游企业财政补贴对自主研发投入诱导效应的异质性和研发效率的异质性,同时研究了财政补贴对企业自主研发投入的滞后性以及研发投入对研发产出的滞后性。研究发现:财政补贴对企业自主研发投入具有明显的诱导效应;企业研发投入和研发产出显著正相关;财政补贴对上游企业自主研发投入的诱导性强于面板集成组装企业;财政补贴对企业自主研发投入的影响以及研发投入对产出的影响均具有一定的滞后性。本文为提升我国半导体显示产业竞争力提供了政策参考,对我国其他高科技产业的发展和产业政策的制定具有一定的参考借鉴意义。 展开更多
关键词 半导体显示产业 财政补贴 研发效率 异质性 滞后性 靶向性
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原状黄土土水特征滞后性研究 预览
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作者 康海伟 李萍 +3 位作者 侯晓坤 李同录 夏增选 张辉 《水文地质工程地质》 CAS CSCD 北大核心 2020年第2期76-83,共8页
现有的土水特征曲线(SWCC)滞后性的研究多针对重塑土,原状黄土土水特征曲线滞后性特征的研究较少。为研究全吸力范围内原状黄土的滞后特征,以泾阳马兰黄土(L1)和离石黄土(L5)为研究对象,采用压力板仪和滤纸法测定增湿和减湿SWCC,采用压... 现有的土水特征曲线(SWCC)滞后性的研究多针对重塑土,原状黄土土水特征曲线滞后性特征的研究较少。为研究全吸力范围内原状黄土的滞后特征,以泾阳马兰黄土(L1)和离石黄土(L5)为研究对象,采用压力板仪和滤纸法测定增湿和减湿SWCC,采用压汞法测定孔隙分布特征,X衍射分析矿物成分。结果表明,在压力板仪测试基质吸力范围内(0~600 kPa),滤纸法和压力板仪测定的SWCC具有一致性,且在减湿过程中两种方法的测试结果更为一致。滤纸法测得的全吸力范围(0~30000 kPa)内,黄土SWCC滞后性存在三段性特征。即在天然含水率(L114.2%、L517.3%)附近,黄土SWCC几乎无滞后性;含水率高于天然含水率一定范围(L1大于19.2%、L5大于18.3%),存在极为明显的滞后性;低于天然含水率一定范围(L1小于11.2%、L5小于15.4%),存在弱滞后性。天然状态下反复干湿循环,导致黄土SWCC在天然含水率附近无滞后性;黄土限制孔隙对墨水瓶效应的增益作用,导致高含水率下黄土SWCC呈强滞后性;黏土矿物的水合作用,导致低含水率下SWCC呈弱滞后性。 展开更多
关键词 土水特征曲线 滞后性 原状黄土 天然含水率 孔隙分布
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基于改进果蝇优化的压电精密定位平台迟滞Bouc-Wen模型辨识 预览
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作者 王龙飞 邓亮 刘萍 《计算机工程与应用》 CSCD 北大核心 2020年第2期242-247,共6页
提出一种基于改进果蝇优化算法(Improved Fruit fly Optimization Algorithm,IFOA)的压电精密定位平台迟滞特性的Bouc-Wen模型参数辨识方法。通过引入交叉因子和自适应搜索步长,IFOA可有效实现全局搜索与局部优化的动态平衡,并通过一种... 提出一种基于改进果蝇优化算法(Improved Fruit fly Optimization Algorithm,IFOA)的压电精密定位平台迟滞特性的Bouc-Wen模型参数辨识方法。通过引入交叉因子和自适应搜索步长,IFOA可有效实现全局搜索与局部优化的动态平衡,并通过一种新的搜索策略提高整体搜索效率和优化精度。将IFOA应用于压电精密定位平台迟滞Bouc-Wen模型的参数辨识。实验辨识结果验证了该方法的有效性和潜力。 展开更多
关键词 迟滞 果蝇优化算法 Bouc-Wen 压电精密定位平台 辨识
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Thickness-dependent coercivity mechanism and hysteresis loops in hard/soft magnets
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作者 Xiao-Jiao Weng Guo-Ping Zhao +2 位作者 Hong Tang Lai-Chuan Shen Yao Xiao 《稀有金属:英文版》 SCIE EI CAS CSCD 2020年第1期22-27,共6页
Two models are established to reveal the underlying coercivity mechanism for SmCo/Fe films,where one model considers a transition layer between hard and soft layers,while the other model does not consider this layer.B... Two models are established to reveal the underlying coercivity mechanism for SmCo/Fe films,where one model considers a transition layer between hard and soft layers,while the other model does not consider this layer.Based on the two models,hysteresis loops,nucleation fields and coercivity are obtained by one-dimensional(1 D)and three-dimensional(3 D)micromagnetic methods.In particular,the calculated nucleation fields(H_N)and coercivity(H_C)match very well with the experimental data.It is found that the increase in the soft phase thickness(Ls)leads to a transition of the coercivity mechanism from nucleation to pinning.Such a pinning is inherently related to nucleation and has both attributes of traditional nucleation and pinning,called as a hybrid coercivity mechanism here.It is general for all hard/soft composites and can be extended to single-phased permanent magnets where defects are inevitable. 展开更多
关键词 COERCIVITY mechanism NUCLEATION PINNING HYSTERESIS LOOPS
液压机批量成形控制策略
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作者 杨俊 苏恒 陈中祥 《锻压技术》 CAS CSCD 北大核心 2020年第1期151-155,共5页
为了提高批量成形金属产品的塑性成形性能,建立了金属液压成形系统的数学模型,并针对追踪周期性位移信号存在滞后和周期性误差的问题,提出了一种基于重复控制和输出反馈的复合控制策略(ROF控制),以提高系统性能,并在金属成形模拟液压实... 为了提高批量成形金属产品的塑性成形性能,建立了金属液压成形系统的数学模型,并针对追踪周期性位移信号存在滞后和周期性误差的问题,提出了一种基于重复控制和输出反馈的复合控制策略(ROF控制),以提高系统性能,并在金属成形模拟液压实验平台上验证了在ROF控制策略作用下的液压缸位移、速度和加速度响应特性,与PID控制进行了对比分析。实验结果表明,采用ROF控制策略,其系统追踪精度能达到0. 05 mm,两个工作循环周期后,追踪过程基本无滞后,能保证金属按指定谐波信号成形,最终能有效地提高批量成形金属件的性能。 展开更多
关键词 ROF控制 液压系统 滞后 周期性信号 重复控制
Test and evaluation of modified TADAS devices with different grades of steel 预览
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作者 Li Zongjing Shu Ganping 《地震工程与工程振动:英文版》 SCIE EI CSCD 2020年第2期451-464,共14页
Triangular-plate added damping and stiffness(TADAS)devices are reliable metallic energy dissipaters for seismic upgrading used in design and retrofitting of civil structures.Conventional TADAS devices are designed wit... Triangular-plate added damping and stiffness(TADAS)devices are reliable metallic energy dissipaters for seismic upgrading used in design and retrofitting of civil structures.Conventional TADAS devices are designed with closedended slots.In this study,a modified form of the TADAS device is proposed with open-ended slots in order to reduce the manufacture cost,facilitate the assembling and avoid abrupt stiffness increase.Cyclic and monotonic loading tests are then conducted to investigate the mechanical characteristics of the modified TADAS devices with regular Q345 steel and lowyield point LY160 steel triangular plates.The test results show that although the hysteresis performances are stable,the cyclic hardening behavior is different between the TADAS specimens with different grades of steel.The TADAS specimen with LY160 triangular plates exhibits more significant overstrength behavior than the one with Q345 triangular plates in cyclic loading,which is unsuitable to be described by the classic Bouc-Wen model.Therefore,a modified Bouc-Wen model is proposed to describe such overstrength behavior.It is shown that the modified model is able to simulate different extent of overstrength behavior in cyclic loading,based on which the cyclic hardening behavior of the TADAS specimen with LY160 triangular plates can be well described. 展开更多
关键词 TADAS HYSTERESIS Bouc-Wen model MONOTONIC CYCLIC OVERSTRENGTH
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基于迟滞回线模型的非线性金属橡胶传递率分析 预览
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作者 余慧杰 朱逸轩 许亚辉 《振动与冲击》 EI CSCD 北大核心 2020年第6期230-235,256,共7页
通过理论和试验对某金属橡胶非线性隔振器的传递特性进行了研究。基于含干摩擦阻尼的非线性迟滞力学模型,采用平均法求出系统的频率响应函数,从理论角度探究不同运动状态下的传递率及实现无谐振的条件;根据频率响应函数确定解锁频率与... 通过理论和试验对某金属橡胶非线性隔振器的传递特性进行了研究。基于含干摩擦阻尼的非线性迟滞力学模型,采用平均法求出系统的频率响应函数,从理论角度探究不同运动状态下的传递率及实现无谐振的条件;根据频率响应函数确定解锁频率与实现无谐振的临界干摩擦力;利用动态加载试验识别隔振器的力学参数,通过振动实验验证了理论结果。所得结论对金属橡胶隔振器的设计和应用具有重要的指导意义。 展开更多
关键词 金属橡胶 迟滞回线 干摩擦阻尼 传递率
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Effect of seismic design details on hysteresis performance of SRC-RC transfer columns 预览
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作者 Wu Kai Zhai Jiangpeng +2 位作者 Xue Jianyang Zhao Hongtie Chen Feng 《地震工程与工程振动:英文版》 SCIE EI CSCD 2020年第1期117-135,共19页
Four types of seismic design details were tested using 11 transfer column specimens and one comparison specimen of RC under low cyclic reversed loading. Test results show that diagonal cracks control the failure patte... Four types of seismic design details were tested using 11 transfer column specimens and one comparison specimen of RC under low cyclic reversed loading. Test results show that diagonal cracks control the failure pattern and damage occurs mainly in the RC section with weak shear capacity in the transfer columns. There is a large difference in the bearing capacity and ductility of the transfer columns according to the test results, which indicates that the strengthening effect of diverse structural measures is quite different. The section ratio of I-section-encased steel and the axial compression ratio also have a great influence on the bearing capacity and ductility. Although the bearing capacity of transfer columns with additional longitudinal bars and additional X bars is relatively large, they have poor deformation capacity. Setting more stirrups along the columns is the best structural measure to enhance the seismic performance. The studs on the I-sectionencased steel by welding can help to complete the stress transfer between the steel and concrete, and avoid performance degradation of the two materials due to bonding failure. 展开更多
关键词 SEISMIC design DETAILS HYSTERESIS performance steel REINFORCED concrete transfer COLUMN energy DISSIPATION
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压电陶瓷驱动器迟滞非线性建模及逆补偿控制 预览
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作者 刘鑫 李新阳 杜睿 《光电工程》 CAS CSCD 北大核心 2019年第8期23-30,共8页
自适应光学系统中的倾斜镜、变形镜通常是应用压电陶瓷驱动器来进行精密位移控制,但压电陶瓷驱动器都有较大的非线性迟滞效应,对系统定位性能造成了一定的影响。为了补偿迟滞现象,需要对迟滞效应进行建模。本文通过引入迟滞算子,使用贝... 自适应光学系统中的倾斜镜、变形镜通常是应用压电陶瓷驱动器来进行精密位移控制,但压电陶瓷驱动器都有较大的非线性迟滞效应,对系统定位性能造成了一定的影响。为了补偿迟滞现象,需要对迟滞效应进行建模。本文通过引入迟滞算子,使用贝叶斯正则化训练算法训练BP神经网络来构建压电陶瓷驱动器迟滞模型,以中国科学院光电技术研究所自主研制的压电陶瓷驱动器为对象开展了实验研究。实验结果表明,通过BP神经网络构建的压电陶瓷驱动器迟滞模型具有较准确的辨识能力,其中正模型的相对误差为0.0127,逆模型的相对误差为0.014。利用所建立的模型,压电陶瓷驱动器的非线性度从14.6%降低到了1.43%。 展开更多
关键词 自适应光学 压电陶瓷驱动器 迟滞效应 神经网络 迟滞算子
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Modeling and compensation of hysteresis for pneumatic artificial muscles based on Gaussian mixture models
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作者 XU JiHao XIAO MuBang DING Ye 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第7期1094-1102,共9页
This paper presents a new data-driven model of length-pressure hysteresis of pneumatic artificial muscles(PAMs) based on Gaussian mixture models(GMMs). By ignoring the high-order dynamics, the hysteresis of PAMs is mo... This paper presents a new data-driven model of length-pressure hysteresis of pneumatic artificial muscles(PAMs) based on Gaussian mixture models(GMMs). By ignoring the high-order dynamics, the hysteresis of PAMs is modeled as a first-order nonlinear dynamical system based on GMMs, and inversion of the model is subsequently derived. Several verification experiments are conducted. Firstly, parameters of the model are identified under low-frequency triangle-wave pressure excitations.Then, pressure signals with different amplitudes, shapes and frequencies are applied to the PAM to test the prediction performance of the model. The proposed model shows advantages in identification efficiency and prediction precision compared with a generalized Prandtl–Ishlinskii(GPI) model and a modified generalized Prandtl–Ishlinskii(MGPI) model. Finally, the effectiveness of the inverse model is demonstrated by implementing the feedforward hysteresis compensation in trajectory tracking experiments. 展开更多
关键词 HYSTERESIS MODELING HYSTERESIS COMPENSATION pneumatic artificial muscles (PAMs) GAUSSIAN MIXTURE model (GMM)
癔症性双眼闭目难睁发作1例
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作者 孟新珍 陈颖 +3 位作者 丁魁 刘惠霞 张灏 周超 《临床心身疾病杂志》 CAS 2019年第6期171-172,共2页
癔症的转换症状临床表现具有多样性,部分症状极为罕见,临床上易误诊.本研究对1例癔症性双眼闭目难挣患者的临床资料进行了分析,以期为临床诊治提供参考.
关键词 癔症 误诊 癔症转换症状 双眼闭目难睁
基于多源遥感数据的干旱监测研究 预览 被引量:1
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作者 孙嵩松 王喜民 《山东农业科学》 2019年第2期150-157,共8页
及时准确地监测干旱可以预防其造成的农作物减产。归一化植被指数(NDVI)在监测植被生长状态、农业干旱方面都表现出了良好的特性。但NDVI对干旱的响应具有一定的滞后性。为了及时准确地监测旱情,本研究将热带降雨测量卫星(TRMM)的降雨... 及时准确地监测干旱可以预防其造成的农作物减产。归一化植被指数(NDVI)在监测植被生长状态、农业干旱方面都表现出了良好的特性。但NDVI对干旱的响应具有一定的滞后性。为了及时准确地监测旱情,本研究将热带降雨测量卫星(TRMM)的降雨数据与NDVI结合起来,构建了基于旬尺度的MNDVI干旱监测模型,并以吉林省农作物生长季为例,通过与历史数据、土壤湿度、叶面积指数(LAI)作相关性分析对其进行验证。结果表明:MNDVI监测的干旱变化图与历史记录有很好的吻合性,表明MNDVI监测干旱的准确性好;将MNDVI和NDVI分别与10cm和20cm土层的土壤湿度进行相关性分析,结果表明MNDVI在一定程度上可以消除NDVI监测干旱方面存在的滞后性;将MNDVI和降雨状态指数(PCI)分别与LAI进行时间序列分析,发现MNDVI与LAI有良好的一致性,而PCI与LAI没有一致性,表明MNDVI对植被的生长状态能够及时响应,可以用来监测农业旱情。 展开更多
关键词 干旱 NDVI 滞后性 TRMM 监测模型
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基于电流轨迹的逆变器开路故障在线故障诊断的一种新方法 预览
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作者 李凯迪 陈春阳 +3 位作者 陈特放 成庶 伍珣 向超群 《中南大学学报:英文版》 SCIE EI CAS CSCD 2019年第3期743-758,共16页
逆变器的安全性与可靠性是电力电子系统稳定运行的不可或缺的条件,而逆变器的故障大部分是由其中的开关元器件运行故障所引起的。本文以滞环电流控制的逆变器作为研究对象,提出了一种可适用于各种控制策略下的开路故障诊断方法。逆变器... 逆变器的安全性与可靠性是电力电子系统稳定运行的不可或缺的条件,而逆变器的故障大部分是由其中的开关元器件运行故障所引起的。本文以滞环电流控制的逆变器作为研究对象,提出了一种可适用于各种控制策略下的开路故障诊断方法。逆变器的开路故障会导致输出相电流畸变,可将此现象作为一个故障特征,并结合比较故障发生前后入相电流方向,实现在半个周期内对开路故障的诊断及定位。此外,该诊断方法既不需要获取系统控制信号,也不需要添加额外传感器。最后,通过dSPACE半实物实验平台,对所提出方法的有效性、可靠性及局限性进行了验证和分析。 展开更多
关键词 故障诊断 滞环 逆变器 故障定位
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基于Duhem算子的极限学习机迟滞建模
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作者 潘海鹏 姜慧斌 赵新龙 《控制工程》 CSCD 北大核心 2019年第3期566-569,共4页
在高精度定位领域中,压电执行器(PEAs)被广泛应用,但其存在着固有的迟滞非线性特性,大大降低了它的控制性能。为了消除迟滞影响,提高压电执行器的控制精度,需建立其迟滞非线性模型。通过引入Duhem迟滞算子来将迟滞的多值映射转化为一对... 在高精度定位领域中,压电执行器(PEAs)被广泛应用,但其存在着固有的迟滞非线性特性,大大降低了它的控制性能。为了消除迟滞影响,提高压电执行器的控制精度,需建立其迟滞非线性模型。通过引入Duhem迟滞算子来将迟滞的多值映射转化为一对一映射关系,应用极限学习机算法逼近迟滞状态与迟滞输出的关系进行迟滞建模。最后应用实验仿真验证了建模方法的有效性。该方法训练速度快、建模精度高,便于实现。 展开更多
关键词 压电执行器:迟滞 Duhem算子 极限学习机
Effects of yaw-roll coupling ratio on lateraldirectional aerodynamic characteristics
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作者 Lin SHEN Da HUANG Genxing WU 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第2期272-280,共9页
Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide di... Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide different coupled motions from low to high angles of attack.A parameter ‘‘coupling ratio' was introduced to indicate the extent of yaw-roll coupling. At each pitch angle, seven coupling ratios were designed to study the yaw-roll coupling effects on the lateraldirectional aerodynamic characteristics systematically. At high angles of attack, the damping characteristics of yawing and rolling moments drastically varied with coupling ratios. In the coupled motions with the rotation taking place about the wind axis, the lateral-directional aerodynamic moments exhibited unsteady characteristics and were different from the ‘‘quasi-steady' results of the rotary balance tests. The calculated results of the traditional aerodynamic derivative method were also compared with the experimental data. At low and very high angles of attack, the aerodynamic derivative method was applicative. However, within a wide range of angles of attack, the calculated results of aerodynamic derivative method were inconsistent with the experimental data, due to the drastic changes of damping characteristics of lateral-directional aerodynamic moments with yaw-roll coupling ratios. 展开更多
关键词 High ANGLES of ATTACK HYSTERESIS Lateral-directional aerodynamic characteristics UNSTEADY Yaw-roll coupling
《航空高压直流供电系统中三相Vienna整流器的控制策略研究》之四——连续和断续模式下Buck变换器的滞环滑模控制设计 预览 被引量:1
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作者 吴辰 李颖晖 +4 位作者 刘远飞 朱喜华 刘聪 韩建定 谢喜太 《大电机技术》 2019年第4期71-76,共6页
为提升Buck变换器的工作性能,降低其作为电子负载对Vienna整流器的不利影响,提出了一种在连续和断续工作模式下的滞环滑模控制策略。首先,设计了以输出电压误差和其微分值为状态量的滑模面,通过对Buck变换器二阶误差模型的相平面分析,... 为提升Buck变换器的工作性能,降低其作为电子负载对Vienna整流器的不利影响,提出了一种在连续和断续工作模式下的滞环滑模控制策略。首先,设计了以输出电压误差和其微分值为状态量的滑模面,通过对Buck变换器二阶误差模型的相平面分析,确定了满足广义滑模条件的区域和连续导电模式、断续导电模式的边界及收敛情况;最终通过仿真和实验銅了上述分析的结论。 展开更多
关键词 BUCK变换器 滑模控制 滞环 性能分析
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Magnetoresistance hysteresis in topological Kondo insulator SmB6 nanowire
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作者 孔令剑 周勇 +2 位作者 宋化鼎 俞大鹏 廖志敏 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第10期105-108,共4页
SmB6, a topological Kondo insulator, with a gapped bulk state and metallic surface state has aroused great research interest. Here, we report an exotic hysteresis behavior of magnetoresistance in individual SmB6 nanow... SmB6, a topological Kondo insulator, with a gapped bulk state and metallic surface state has aroused great research interest. Here, we report an exotic hysteresis behavior of magnetoresistance in individual SmB6 nanowire in a temperature range in which both surface and bulk states contribute to the total conductance. Under a magnetic field parallel to the SmB6 nanowire, the resistance suddenly increases at the turning point from up-sweep to down-sweep of the magnetic field. The magnetoresistance hysteresis loops are well consistent with the magnetocaloric effect. Our results suggest that the SmB6 nanowires possess potential applications in the magnetic cooling technology. 展开更多
关键词 TOPOLOGICAL KONDO insulator MAGNETOCALORIC effect MAGNETORESISTANCE HYSTERESIS
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