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分析了磁悬浮轴承电磁力与其电流和转子位移非线性关系产生的原因,结合国内外文献资料,主要从磁轴承偏置磁场以及本质非线性两方面对磁悬浮轴承力与电流及其位移关系线性化策略进行概述。 相似文献
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Wei LI De-ren SHENG Jian-hong CHEN Yong-qiang CHE 《浙江大学学报(A卷英文版)》2014,15(11):883-895
研究目的：研究双盘双跨转子/轴承/汽封系统在非线性油膜力和非线性汽封力共同作用下的动力学特性,分析了转子转速、密封力、油膜力和联轴器刚度等因素对转子稳定性的影响。创新要点：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型,使得双跨多节点的转子系统数值求解更加容易。研究分析转子转速、非线性密封力、非线性油膜力和联轴器刚度等因素对转子稳定性的影响,为大型转子系统的设计提供理论基础。研究方法：采用Hamilton原理和有限元方法建立双盘双跨转子/轴承/汽封系统模型（图1和2）。应用四阶Runge-Kutta法进行数值求解,并采用轴承处、圆盘处的分岔图、时程图、庞加莱映射图、频率图和相轨迹图等来分析转子系统的动态特性。重要结论：1.通过数值计算分析,转子的转速、非线性汽封力、非线性油膜力和联轴器的刚度对双跨转子的稳定性有重要的影响作用。2.随着转速的上升,双跨转子系统从最初的稳定运动,到三倍周期运动,到准周期运动和多倍周期运动交替出现,运动特性相比单跨转子系统要更为复杂。 相似文献
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Giant magnetostrictive actuators （GMAs） often work in a close-loop feedback system. This system needs independent sensors which may be difficult to be fixed, besides, excessive sensors may cause more unpredicted problems in a large system. This paper aims to develop a self-sensing GMA. An observer based on piezomagnetic equations is constructed to estimate the stress and strain of the magnetostrictive material. The observer based self-sensing approach depends on the facts that the magnetic field is controllable and that the magnetic induction is measurable. Aiming at the nonlinear hysteresis in magnetization, a hysteresis compensation observer based on Preisach model is developed. Experiment verified the availability of the observer approach, and the hysteresis compensation observer has higher tracking precision than linear observer for dynamic force sensing. 相似文献
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Traditional studies on integrated statistical process control and engineering process control (SPC-EPC) are based on linear autoregressive integrated moving average (ARIMA) time series models to describe the dynamic noise of the system.However,linear models sometimes are unable to model complex nonlinear autocorrelation.To solve this problem,this paper presents an integrated SPC-EPC method based on smooth transition autoregressive (STAR) time series model,and builds a minimum mean squared error (MMSE) controller as well as an integrated SPC-EPC control system.The performance of this method for checking the trend and sustained shift is analyzed.The simulation results indicate that this integrated SPC-EPC control method based on STAR model is effective in controlling complex nonlinear systems. 相似文献
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REN Wan-bin CUI Li LUO Fu-biao ZHAI Guo-fu 《浙江大学学报(A卷英文版)》2007,8(3):434-438
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. 相似文献
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介绍了水轮机组发电机转子在转动过程中的三种偏心:静偏心、振动偏心和转动偏心,建立了转子在不平衡电磁力作用下的非线性振动微分方程。采用数值方法分析了转动偏心和静偏心对轴系电磁振动特性的影响,结果表明,这两种偏心与电磁力呈非线性关系,随着偏心的增大使不平衡磁拉力作用不断加强,机组的横向振动固有频率有所降低,转子和转轮的振幅不断增大,倍频共振时的振幅也显著加大,转子系统展现出非常复杂的非线性动力学特征。 相似文献
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尝试用数学模型去解决磁介质与磁荷系统的磁化、磁性质等问题，并用统一的、严谨的理论框架去解决静磁场问题。通过建立磁荷与磁介质球系统磁标势的数学模型，从理论上构建磁荷与磁介质球系统的一般框架，利用该模型可以引导分析均匀磁场中磁介质球的磁标势，磁屏蔽以及均匀磁化铁球等问题。借此还可以进一步分析磁荷与磁介质系统的磁性质、磁场、磁力等问题。解决了磁荷、磁矩与磁介质系统磁场及磁力计算方法等问题，为进一步研究磁单极与磁场、磁介质之间的性质和关系奠定理论基础。 相似文献
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lintroductionInrecent20years,owingtotilerapiddevelopnlentofco.nputertechnology,tiletiniteelenlent1netnodforstndyingelectronlagneticfieldwasdevelopedti.onltheoreticalconlputationtoconnnercialsoftwarepackageinvestigation,towardstiledirectionofCAD,andgradnan… 相似文献
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Rukiye Ayan Mine Isiksal Bostan 《International Journal of Science and Mathematics Education》2018,16(3):503-518
In this study, we investigate sixth, seventh, and eighth grade students’ achievement in nonlinear (quadratic or cubic) proportional problems regarding length, area, and volume of enlarged figures. In addition, we examine students’ solution strategies for the problems and obstacles that prevent students from answering the problems correctly by using a mixed method research design. A total of 935 middle school students were given a paper-pencil test and 12 of them were interviewed. Findings indicated that achievement of the participants were low and that students used a limited number of strategies for solving the problems. In addition, these strategies were found to have lacked the argument of the linear proportional and nonlinear proportional relationships among length, area, and volume concepts for most of the participants’ answers. Moreover, analysis revealed that the confusion of linear proportional and nonlinear proportional relationships and misinterpretation of additive and multiplicative relationships were serious obstacles while solving the nonlinear proportional problems related to the area and volume of enlarged figures. 相似文献
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邱荒逸 《连云港职业技术学院学报》2005,18(2):79-80
磁偶极子与电偶极子一样，都是非常实用的物理模型。在现行少课时教改的趋势下，让同学尽早认识磁偶极子是一桩非常有意义的事。教材中对磁偶极子虽有论述，但用到的数学既较深奥，也有点繁琐，直接导致初学者在认识上产生障碍。在教学中，磁偶极子与磁场的相互作用力运用培安力公式来计算，方法直观易懂，学生较易接受。 相似文献
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基于麦克斯威尔方程,给出导电薄板的非线性磁弹性振动方程,以及磁场环境下的电动力学方程和电磁力表达式。在此基础上,应用伽辽金法导出相应的非线性振动微分方程组,研究横向恒定磁场中周期载荷作用下梁式薄板的稳定性问题。根据李雅普诺夫近似稳定性理论,对稳态解的稳定性进行分析,得到稳定性的判定条件。通过对算例特征值的求解对振动的稳定性进行分析。 相似文献
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A New Interpretation of Augmented Subscores and Their Added Value in Terms of Parallel Forms 
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下载免费PDF全文 Sandip Sinharay 《Journal of Educational Measurement》2018,55(2):177-193
The value‐added method of Haberman is arguably one of the most popular methods to evaluate the quality of subscores. The method is based on the classical test theory and deems a subscore to be of added value if the subscore predicts the corresponding true subscore better than does the total score. Sinharay provided an interpretation of the added value of subscores in terms of scores and subscores on parallel forms. This article extends the results of Sinharay and considers the prediction of a subscore on a parallel form from both the subscore and the total raw score on the original form. The resulting predictor essentially becomes the augmented subscore suggested by Haberman. The proportional reduction in mean squared error of the resulting predictor is interpreted as a squared multiple correlation coefficient. The practical usefulness of the derived results is demonstrated using an operational data set. 相似文献
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This paper presents a bi-directional permanent-magnet linear actuator for directly driving electrohydraulic valves with low power consumption. Its static and dynamic performances were analyzed using the 2D finite element method, taking into account the nonlinear characterization and the eddy current loss of the magnetic material. The experiment and simulation results agree well and show that the prototype actuator can produce a force of±100 N with the maximum power being 7 W and has linear characteristics with a positive magnetic stiffness within a stroke of ±1 mm. Its non-linearity is less than 1.5% and the hysteresis less than 1.5%. The actuator＇s frequency response （-3 dB） of the displacement reaches about 15 Hz, and the most significant factor affecting the dynamic performance is identified as the eddy current loss of the magnetic material. 相似文献
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XIANG Yu-min 《重庆大学学报(英文版)》2008,7(3):210-215
To determine the motion of a charged particle in a magnetic field produced by a current flowing along a long column conductor, the equation of the motion was established on the basis of Lorentz force. Qualitative analysis and quantitative solutions demonstrated that the motion contains nonlinear oscillation. The oscillation can be treated as the perturbation of the helical motion, Which the particle undergoes in a special condition. The general motion is superposition of two helixes, one as an axis spiraled by another. It is proven that the oscillation is stable. 相似文献
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杨清华 《邢台职业技术学院学报》2014,(5):80-83
本文中给出了由一对磁环轴向充磁组成的轴向永磁轴承,并采用等效电流法计算两磁环之间的轴向力,阐明了永磁轴承在某一方向不稳定的原因。根据特定的永磁轴承实体模型,给出了其动力学方程,并对轴向的非线性运动方程用迦辽金法求出了方程的解析解。通过利用matlab软件进行仿真,证明了特定的永磁轴承在小气隙内磁环可以获得小振幅的稳定模态。 相似文献
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针对四轮独立转向电动汽车,结合轮胎“魔术公式”模型,建立了基于阿克曼转向定理的二自由度非线性转向模型,并提出一种基于模糊策略的方法对其质心侧偏角进行控制.整车系统仿真输入为左前轮车轮转角,模糊控制器以质心侧偏角等于零为控制目标来控制左后轮转角,同时用阿克曼转向定理来调整右前轮和右后轮转角,由此实现四轮独立转向.仿真结果与传统前轮转向、传统四轮比例转向进行比较,结果表明,利用模糊控制对基于阿克曼定理所建立的非线性四轮独立转向模型的控制策略是有效的,控制效果良好. 相似文献
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与力学中用物体势能的空间变化率来计算力的方法相似,假定受力物体在受力方向上发生微小的"虚位移",根据不同情况下的电源供给系统的能量、系统增加的电磁场能量、静电场力和磁场力做的功之间的关系,就可方便地求出物体受到的静电场力和磁场力. 相似文献
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Günter B 《浙江大学学报(A卷英文版)》2009,10(2)
We present a derived grid-based model for the simulation of pedestrian flow. Interactions among pedestrians are considered as the result of forces within a certain neighbourhood. Unlike the social force model, the forces here, as in Newtonian physics, are proportional to the inverse of the square of the distance. Despite the notion of neighbourhood and the underlying grid, this model differs from the existing cellular automaton (CA) models in that the pedestrians are treated as individuals. Bresenham's algorithm for line rastering is applied in the step calculation. 相似文献
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到目前为止,尽管还没有发现单个"磁荷"的存在,但是用等效的"磁荷"观点,解决一些磁性问题却颇为简便.本文将借助电矩在电场中受到的力、力矩及其在电场中所具有的能量的讨论方法,应用简要的"磁荷"观点,普通物理学的方法,得到磁矩在磁场中受到的力、力矩及其所具有的势能. 相似文献