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Modal disturbance investigation of rod-shaped ultrasonic motor using bending vibrations

ZHANG Jiantao, ZHU Hua, ZHAO Chunsheng

《机械工程前沿（英文）》 2008年第3卷第3期页码 343-347 doi: 10.1007/s11465-008-0058-6

摘要： Modal disturbance of a rod-shaped ultrasonic motor using bending vibrations can cause problems such as low motor efficiency, instability, and poor control. In this paper, a dynamic analysis model of a stator is created on the basis of the finite element method (FEM) and Hamilton principle. The modal frequency sensitivities of the stator to the structure parameters are investigated by modal analysis. Accordingly, the structure parameters of the stator are modified to separate working modes from disturbance modes. A rod-shaped ultrasonic motor stator is fabricated, and the experimental results of its amplitude frequency response characteristics show that the purpose of modal separation is achieved. The frequency separation between working modes and disturbance modes is more than 2 kHz. The validity of the method is verified.

关键词： Hamilton principle disturbance separation frequency separation dynamic analysis

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Recognition of diamond grains on surface of fine diamond grinding wheel

HUO Fengwei, JIN Zhuji, KANG Renke, GUO Dongming, YANG Chun

《机械工程前沿（英文）》 2008年第3卷第3期页码 325-331 doi: 10.1007/s11465-008-0071-9

摘要： The accurate evaluation of grinding wheel surface topography, which is necessary for the investigation of the grinding principle, optimism, modeling, and simulation of a grinding process, significantly depends on the accurate recognition of abrasive grains from the measured wheel surface. A detailed analysis of the grain size distribution characteristics and grain profile wavelength of the fine diamond grinding wheel used for ultra-precision grinding is presented. The requirements of the spatial sampling interval and sampling area for instruments to measure the surface topography of a diamond grinding wheel are discussed. To recognize diamond grains, digital filtering is used to eliminate the high frequency disturbance from the measured 3D digital surface of the grinding wheel, the geometric features of diamond grains are then extracted from the filtered 3D digital surface, and a method based on the grain profile frequency characteristics, diamond grain curvature, and distance between two adjacent diamond grains is proposed. A 3D surface profiler based on scanning white light interferometry is used to measure the 3D surface topography of a #3000 mesh resin bonded diamond grinding wheel, and the diamond grains are then recognized from the 3D digital surface. The experimental result shows that the proposed method is reasonable and effective.

关键词： topography frequency disturbance filtering analysis wavelength

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Virtual reality system of manned maneuvering unit taking into consideration the disturbance from an astronaut

CHENG Jian, FAN Xiu-min, XU An, HONG Xin, HUANG Wei-dong

《机械工程前沿（英文）》 2006年第1卷第3期页码 282-287 doi: 10.1007/s11465-006-0042-y

摘要： This paper describes a manned maneuvering unit (MMU) virtual reality system. Based on the dynamics/kinematics model of an astronaut equipped with an MMU, a disturbance model of the astronaut s arms under zero gravity conditions is developed. After measuring three initial-position information, the astronaut s arms tracking information is inputted by some tracker setting on an operator using real-time emendation and correction. Finally, the paper presents two different results between loading and unloading the disturbance model within the progress of simulation. From the different results, we find that the motion of an astronaut s arms has greater influence over space walking with the same control mode. The MMU virtual reality provides a new method for the simulation of real space walking, and also a perfect method for developing prototype MMU.

关键词： real-time emendation disturbance maneuvering MMU correction

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Application of a Novel Fuzzy Clustering Method Based on Chaos Immune Evolutionary Algorithm for Edge Detection in Image Processing

《机械工程前沿（英文）》 2006年第1卷第1期页码 85-89 doi: 10.1007/s11465-005-0023-6

摘要：

A novel fuzzy clustering method based on chaos immune evolutionary algorithm (CIEFCM) is presented to solve fuzzy edge detection problems in image processing. In CIEFCM, a tiny disturbance is added to a filial generation group using a chaos variable and the disturbance amplitude is adjusted step by step, which greatly improves the colony diversity of the immune evolution algorithm (IEA). The experimental results show that the method not only can correctly detect the fuzzy edge and exiguous edge but can evidently improve the searching efficiency of fuzzy clustering algorithm based on IEA.

关键词： disturbance amplitude disturbance diversity generation processing

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针对主动磁悬浮轴承干扰抑制的一类结合迭代学习控制与干扰观测器的解决方法 None

Ze-zhi TANG, Yuan-jin YU, Zhen-hong LI, Zheng-tao DING

《信息与电子工程前沿（英文）》 2019年第20卷第1期页码 131-140 doi: 10.1631/FITEE.1800558

摘要：针对主动磁悬浮轴承系统，传统迭代学习控制可实现高精度轨迹跟踪，但系统扰动必须限定为不随迭代变化。基于目前方法，提出一种抑制主动磁悬浮轴承系统中随迭代变化的不匹配扰动方法。在该方案中，结合经典迭代学习控制和普适性扩张观测器，在使用输出反馈信息情况下，可在每次迭代过程中估计并抑制外界变化干扰。分析证明了整个闭环系统的收敛性，同时，仿真结果表明，相比传统迭代学习控制，该控制方法轨迹跟踪性能更加优良。

关键词：主动磁悬浮轴承；迭代学习控制；干扰观测器

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Polycystic ovary syndrome

Zi-Jiang CHEN, Yuhua SHI

《医学前沿（英文）》 2010年第4卷第3期页码 280-284 doi: 10.1007/s11684-010-0098-2

摘要： Polycystic ovary syndrome (PCOS) is a common gynecologic endocrinopathy. The pathogenesis of PCOS is associated with both heredity and environment. PCOS has adverse impacts on female endocrine, reproduction, and metabolism. PCOS can impact women’s reproductive health, leading to anovulatory infertility and higher rate of early pregnancy loss. PCOS has additional metabolic derangements, such as insulin resistance, impaired glucose tolerance, and dyslipidemia. The risks of diabetes, cardiovascular disease, hypertension, metabolic syndrome, and endometrial cancer among PCOS patients are significantly increased as well.

关键词： polycystic ovary syndrome genetics metabolic disturbance

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用可压缩流涡方法模拟叶轮机动静叶的相互作用

陈矛章,彭波

《中国工程科学》 2000年第2卷第2期页码 15-23

摘要：

本课题组发展了一种扰动涡方法，用以研究叶轮机内动、静叶相互作用^[1，2]。其优点是物理图画清楚，计算收敛快。它采用了一个重要假设：扰动胀量为零，从而大大简化了计算过程。文章的目的是研究此假设的影响，并取消此假设，使扰动涡方法建立在完全严格的数学基础上。由于取消了“扰动胀量为零的假设，需要耦合求解扰动质量方程、扰动涡量输运方程和扰动能量输运方程。这是文章与文献[1，2]的主要区别。

文献[1,2]对NASA67压气机第一级内由于动、静叶间的相互作用引起的非定常流动过程作了数值模拟，并与试验结果作了对比。文章也作了同样的算例，以研究扰动胀量为零的影响。数值模拟结果表明，在引入了扰动胀量后，用扰动涡方法模拟动静干涉仍保持较好的收敛性和收敛速度，且与试验的符合程度更好。文章强调指出，即使对于非定常可压流，为满足无渗透边界条件所需的运动分量也是用椭圆类的拉普拉斯方程描述，而不是用双曲类的方程描述。“扰动胀童为零”不能等同于扰动运动为不可压。

关键词：叶轮机动、静叶相互作用扰动涡方法非定常流可压缩流

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A frequency error estimation for isogeometric analysis of Kirchhoff–Love cylindrical shells

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0006-x

摘要： A frequency error estimation is presented for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells using both quadratic and cubic basis functions. By analyzing the discrete isogeometric equations with the aid of harmonic wave assumption, the frequency error measures are rationally derived for the quadratic and cubic formulations for Kirchhoff–Love cylindrical shells. In particular, the governing relationship of the continuum frequency for Kirchhoff–Love cylindrical shells is naturally embedded into the frequency error measures without the need of explicit frequency expressions, which usually are not trivial for the shell problems. In accordance with these theoretical findings, the 2nd and 4th orders of frequency accuracy are attained for the isogeometric schemes using quadratic and cubic basis functions, respectively. Numerical results not only thoroughly verify the theoretical convergence rates of frequency solutions, but also manifest an excellent magnitude match between numerical and theoretical frequency errors for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells.

关键词： isogeometric analysis Kirchhoff–Love cylindrical shell free vibration frequency error convergence

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Calculation of collision frequency function for aerosol particles in free molecule regime in presence

Xiaowei LUO, Yannick BENICHOU, Suyuan YU

《能源前沿（英文）》 2013年第7卷第4期页码 506-510 doi: 10.1007/s11708-013-0275-5

摘要： The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas (free molecule regime). Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.

关键词： aerosol particles collision frequency function coagulation

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Fuel variability effect on flickering frequency of diffusion flames

Jizhao LI, Yang ZHANG

《能源前沿（英文）》 2009年第3卷第2期页码 134-140 doi: 10.1007/s11708-009-0034-9

摘要： It is known that fuel variability of different gas suppliers may cause combustion instability in a gas turbine combustor. Mechanisms that control the time scale of the heat release oscillations and acoustic pressure perturbations are both physical and chemical in nature, and thus can be influenced by changes in fuel composition. The intent of this study is to investigate the fuel variability on the flickering frequency of diffusion flames in the hope of understanding some of the fundamental aspects of fuel variability effect on the dynamics of combustion. Experiments were conducted at atmospheric pressure with a matrix of methane and propane blends. An optical fibre system was applied to capture simultaneously the flame flickering at two different light frequencies (430 nm and 516 nm), which provided a means of comparing the chemistry change. It was found that the low frequency oscillation of flow and flame structures depended only weakly on the exit velocities of the fuel, while ambient conditions had a significant effect on flickering frequencies and spectrum. The results of using CH and C H as test fuels at different flow rates showed very little variations, with peak frequencies at 11-13 Hz. When the jet flame was not disturbed, harmonics to at least the third mode were obtained in most of these cases. However, the cases which included CH /C H splits of 90/10, 85/15 and 80/20 by volume showed that unstable flickering frequencies and flame harmonics were not observed. When a mixture of methane/propane at a ratio of 1:1 was used the peak flickering frequency was around 6 Hz, and slight disturbance in the environment would cause the harmonics to disappear. Mechanisms thought to produce changes in the dynamic response and frequency harmonics were discussed.

关键词： fuel variability flickering frequency diffusion flames dynamics of combustion

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Capacity limitation of nuclear units in grid based on analysis of frequency regulation

Yiping DAI, Pan JIANG, Lin GAO, Weimin KAN, Xiaoqing XIAO, Ge JIN

《能源前沿（英文）》 2012年第6卷第2期页码 148-154 doi: 10.1007/s11708-012-0174-1

摘要： The increasing capacity of nuclear units in power grid poses threat to system stability and security. Load disturbance may cause overspeed of the units and trigger the overspeed protection controller (OPC). Repeating actions of valves have a strong impact on the security of the equipment and may result in a collapse of the power system. Based on the analysis of frequency regulation, mathematic models for nuclear units in the grid are established in this paper to simulate the dynamic process when load disturbance occurs. The critical action of the OPC is proposed as the constraint of safe operation for the units. The relationship between different styles of frequency regulation and the allowable capacity of the nuclear units in the grid is discussed. This research can help to estimate the capacity limitation of nuclear units in the grid.

关键词： nuclear units capacity overspeed primary frequency control (PFC) second frequency control (SFC)

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Oscillation frequency of simplified arterial tubes

Hui AN, Fan HE, Lingxia XING, Xiaoyang LI

《机械工程前沿（英文）》 2009年第4卷第3期页码 300-304 doi: 10.1007/s11465-009-0038-5

摘要： To construct the spatial kinetic equation of an arterial tube and obtain its radial natural frequency, a linear-elastic and small deformation condition is assumed. The theoretical analysis is first presented and the finite element method is then used to numerically simulate the spatial kinematics. The results show that the first-order frequency is 15.8 Hz and the obtained exact analytical solutions agree well with numerical solutions, which proves that the theoretical analysis and numerical simulation are both correct.

关键词： spatial kinematics natural frequency finite element method

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基于扩展干扰观测器的电液执行器的模糊阻抗控制 Regular Papers-Research Articles

Ming-jie LI, Jian-hua WEI, Jin-hui FANG, Wen-zhuo SHI, Kai GUO

《信息与电子工程前沿（英文）》 2019年第20卷第9期页码 1221-1233 doi: 10.1631/FITEE.1800155

摘要：在本文中，我们同时处理遭受外干扰及参数不确定影响的单出杆电液执行器的速度控制和力控制。在某些应用中，速度控制和力控制两者都有要求。阻抗控制和扩展干扰观测器的结合可以解决该问题。阻抗控制可调节执行器的速度和输出力之间的动态关系，有助于执行器与作用环境或者工件间避免冲击和保持合适的接触力。阻抗规则参数可由模糊算法调节。扩展干扰观测器被用于补偿外部干扰和参数不确定性，实现精确的速度跟踪。为扩展干扰器的开发，提出精确的负载力动力学模型。分析了系统稳定性。实验数据表明所提控制算法具有高精度速度跟踪性能，同时具有良好的力调节能力，在工程机械和装配中具有较大应用前景。

关键词：模糊控制；阻抗控制；干扰观测器；参数不确定性；电液执行器

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Parameter identification of interconnected power system frequency after trip-out of high voltage transmission

Xuzhan ZHOU,Shanshan LIU,Mingkun WANG,Yiping DAI,Yaohua TANG

《能源前沿（英文）》 2014年第8卷第3期页码 386-393 doi: 10.1007/s11708-014-0323-9

摘要： Accurate modeling and parameters of high voltage (HV) grid are critical for stability research of system frequency. In this paper, simulation modeling of the system frequency was conducted of an interconnected power system with HV transmission lines in China. Based on recorded tripping data of the HV transmission lines, system parameters were identified by using genetic algorithm (GA). The favorable agreement between simulation results and recorded data verifies the validity of gird models and the accuracy of system parameters. The results of this paper can provide reference for the stability research of HV power grid.

关键词： high voltage (HV) grid frequency stability parameter identification primary frequency regulation (PFR)

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Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

《机械工程前沿（英文）》 2013年第8卷第2期页码 146-149 doi: 10.1007/s11465-013-0260-z

摘要：

To predict more precisely the frequency of force-balanced micro accelerometer with different bias voltages, the effects of bias voltages on error sensitivity of frequency is studied. The resonance frequency of accelerometer under closed loop control is derived according to its operation principle, and its error sensitivity is derived and analyzed under over etching structure according to the characteristics of Deep Reaction Ion Etching (DRIE). Based on the theoretical results, micro accelerometer is fabricated and tested to study the influences of AC bias voltage and DC bias voltage on sensitivity, respectively. Experimental results indicate that the relative errors between test data and theory data are less than 7%, and the fluctuating value of error sensitivity under the range of voltage adjustment is less than 0.01 μm . It is concluded that the error sensitivity with designed parameters of structure, circuit and process error can be used to predict the frequency of accelerometer with no need to consider the influence of bias voltage.

关键词： Micro-Electro-Mechanical Systems (MEMS) micro accelerometer force-balanced micro accelerometer frequency error sensitivity