基于地图预处理及改进A~*算法的路径规划

针对移动机器人路径规划中栅格地图建模及A~*算法搜索效率问题,设计了一种基于地图分区预处理及改进A~*算法的路径规划。首先,基于K-Means聚类算法对栅格地图进行分区并量化各局部区域的复杂度;然后,改进A~*算法的评价函数和子节点选择方式并依据地图区域的复杂度生成有效的搜索空间;最后,改进Floyd算法对路径进行双向平滑度优化处理,并通过添加防碰撞安全距离系数,使路径与障碍物保持安全距离。实验仿真结果表明,本文所设计的算法可提高A~*算法的搜索效率和灵活性,增加路径的平滑度和安全性。     

基于光谱的多色分色中颜色分区判断算法的研究

目的研究基于光谱多色分色中颜色分区的判断算法。方法提出一种基于光谱的颜色分区判断算法,该算法引入特征光谱的提取和匹配算法,并在此基础上设计颜色分区判断算法。针对该算法流程中的参数,设计实验进行推算。结果将光谱曲线的值域范围划分为12个等级,目标光谱与分区的距离和目标光谱与所有分区距离最小值的差值小于14%,预测光谱与目标光谱的RRMS小于0.01,色差小于1.5时,能够得到最佳的分区判断结果,每个色块的判断次数为1.93,约为遍历算法的24%。结论提出的基于光谱颜色分区算法能够有效地对目标光谱所在分区进行准确判断,简化基于光谱的多色分色算法流程。     

面向Kafka共识消息传输的负载均衡算法

Kafka是一种高吞吐量消息中间件,但该算法存在负载均衡导致消费者消息处理效率下降的问题。本文提出一种改进的Kafka负载均衡算法,其中协调者基于消费者和分区的对应关系,根据不同的负载均衡场景优化调整消费者数目,按照业务负载倒序的方式更新消费者和分区的对应关系,优先处理负载较大的业务分区,提高消息传输效率,并且搭建Fabric联盟链验证分析算法的性能。实验结果表明,本算法在中央处理器(CPU)资源消耗比其他算法低5%的情况下,共识速度提升了2%～7%,并且在6个Kafka节点中3个宕机的情况下仍然能共识上链,提升了Kafka负载均衡算法的效率和稳定性。     

边界元分析系统BEAP及其在工程中应用

本文介绍了作者们研制的BEAP边界元分析系统,该系统采用子域方法及相应的变带宽算法,从而有效地利用了边界子域、罚子域、重复子域等应用技巧。该系统成功地解决了等径三通管接头的应力分析,轴承圈弹性变形,裂纹应力强度因子计算。     

面向宏观基本图的多模式交通路网分区算法

为探究不同模式交通流之间的相互作用关系,提出一种考虑路网多模式属性的分区算法。以社会车和公交车速度和路段邻接关系为划分依据,提出初始子区划分、子区合并、子区边界调整的三步分区算法。以深圳多模式交通数据为例进行了子区划分实验,结果表明本文算法相较于其他分区算法能得到两种模式异质性都较低的交通小区;通过识别路网子区中的多模式宏观基本图,验证了实际交通路网中存在多模式宏观基本图。     

颜色分区理论误差分析研究

分析了颜色分区理论,对颜色分区理论产生误差的原因进行了剖析,提出了分区边界以及共享区域的概念和分区边界描述的修正方法,在此基础上确定了判断颜色是否在共享区域内的规则。通过构建多色分色模型对修正算法进行了检验,对进行共享区域判断和不进行共享区域判断进行了比较。分色实验结果表明,分区边界描述修正方法能很好地解决颜色分区理论产生的误差,能进一步提高多色分色模型的精度。     

基于分区的 RBF 神经网络颜色空间转换模型的研究

根据 CMYK 颜色空间的特点,对其进行了分区处理,利用 RBF 神经网络最佳逼近性能、全局最优特性和高度非线性转换的优势,构建了基于 RBF 神经网络每个颜色空间分区转换的正向和反向模型。 通过训练样本建模和测试仿真实验,并对最后的实验数据分析处理,最终获得了一个较好的神经网络模型,并且模型的精度非常高。     

永磁风力机并网逆变器的研究

通过分析永磁风力发电机并网逆变器的结构与控制策略,本文提出了一种基于SVPWM控制策略的三电平逆变器简化空间矢量分区和作用时间的算法。通过仿真实验验证了该控制策略的正确性与有效性,仿真结果表明三电平逆变器具有极大的优越性。同时,本文提出一种有功功率与无功功率解耦闭环控制方案。     

无网格彼得洛夫伽辽金法在大变形问题中的应用

将无网格局部彼得洛夫伽辽金(MLPG)法推广应用于大变形问题。导出了非线性局部子域对称弱形式,通过对该弱形式进行线性化得到了用于非线性计算的MLPG格式,并对MLPG的计算速度进行了优化,使MLPG成为一种复杂度为O(N)的算法。几何非线性和几何与材料双重非线性的数值算例表明,相对有限元方法,MLPG在处理此类大变形问题时收敛性好,精度高,并能减小有限元分析中易遇到的网格畸变带来的困难。     

影像边缘检测Prewitt算子的改进算法

本文对Prewitt经典算子进行了分析,根据算法的计算规律提出了一种改进的计算方法,通过对常规算法与改进算法的计算量进行比较分析,从理论上说明了改进算法具有简洁的处理步骤,提高了处理的速度;又通过对200幅256×256影像的具体实验证明,改进算法不仅拥有与原算法相同的效果,而且,处理时间显著缩短。     

某跨音速高压涡轮非定常流动数值模拟研究

通过求解三维非定常雷诺平均N-S方程模拟某跨音速高压涡轮非定常流场,研究涡轮内非定常流动特征。通过对静子尾迹及静子尾缘激波和转子叶排之间的相互干涉过程进行详细分析,发现定常/非定常模拟方法获得的涡轮总体性能参数基本一致但流场存在较大差异。静子尾迹是导致涡轮流场非定常性的重要因素之一:在转子叶栅通道中部和下部,静子尾迹和转子叶片附面层及下通道涡发生明显干涉,并导致通道中下部损失周期性波动幅度较大,此外尾迹和下通道涡间的干涉作用在转子尾缘处诱导出高频脱落涡。静子尾缘激波也是导致涡轮流场非定常性的原因之一,激波和转子叶片作用形成复杂的波系结构,对涡轮流场影响显著:一方面激波/附面层干涉导致转子和静子的吸力面产生周期性变化的高温区域;另一方面激波撞击叶片导致叶片表面的气流在激波后出现分离,对转子静压分布产生影响,使得转子叶片表面载荷出现明显的非定常性,进而导致涡轮输出功的周期性波动十分剧烈。     

Some features of molecular flow in a rotor-stator row with real topology

Free molecular flow within rotor and stator rows of a turbomolecular pump is simulated using test-particle Monte Carlo method. The solution is performed in an inertial reference frame where molecular paths are straight lines. The molecules are followed both in rotor and stator in a similar system of coordinates. The real three-dimensional topology of the blade rows including blade thickness, clearance between blade tip wall and casing, and the gap between rotor and stator are considered. Good agreement between numerical results of several rotor-stator combinations and known experimental data confirms the validity of the presented algorithm. The flow analysis shows that although the molecules tend to collect in high radius region, however the concentration of molecules attenuates in the clearance region of rotor, and accentuates in the clearance region of stator. Parametric study of a rotor-stator row shows that the effect of the gap between rotor and stator is significant for the first stages of TMPs with large blade angles and wide spacings, while it is negligible for the last blade rows with small angles and small spacings.     

质量偏心旋转机械转子-机匣系统碰摩的失效研究

针对仅考虑质量偏心的Jeffcott转子-机匣系统碰摩的动力学方程，进行了旋转机械转子-机匣系统碰摩可靠性分析，研究了转轴刚度和阻尼，定子刚度和阻尼，偏心距和定子径向刚度对可靠度的影响，并给出了数值分析解。     

Rotor Design and Finite Element Analysis of Traveling Wave Rotaty Ultrasonic Motor

The dynamic transfer mechanism of the traveling wave rotary ultrasonic motor rotor-stator' s contact surface is studied in the paper and the key parts stator and cone flexible rotor of ultrasonic motor are designed.The three-dimensional contact model and finite element model considering the radial sliding between the rotor and the stator are established. The relation between the stator surface particle that amplitude frequency characteristics,resonance speed,radial displacement of ultrasonic motor and the tooth height are analyzed. Mass point radial relative displacement of contact surface between the cone flexible rotor,flexible rotor and the stator are contrasted. The cone flexible rotor is better placed on the surface of the stator tooth through its elastic deformation is interpreted. The cone flexible rotor reduces the radial slip between the stator and the output efficiency of ultrasonic motor is improved. The displacement trajectory of the stator surface is synthesized in a row wave cycle. The method of the stator mass point elliptical motion drives the rotor rotation is verified.     

基于定子振动特征的转子绕组短路故障识别

分析了汽轮发电机转子绕组匝间短路故障和转子不平衡故障时定、转子径向振动特征。当转子绕组匝间短路故障发生时,转子基频振动增加,定子二倍频振动减小;当转子不平衡故障发生时,转子基频振动增加,定子二倍频振动增加,不同于转子绕组匝间短路故障时的定子振动特征。在此基础上提出了基于定子振动信号的转子绕组匝间短路故障识别方法,与传统的单纯利用转子振动信号的诊断模型相比,可有效识别转子绕组匝间短路故障和转子不平衡故障。最后实测了SDF-9型故障模拟发电机定、转子径向振动信号,与理论分析结果基本吻合。     

Effect of the hydrodynamic bearing on rotor/stator contact in a ring-type ultrasonic motor

A hybrid numerical analysis that includes the hydrodynamic bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional time-dependent compressible Reynolds equation is solved numerically by a second-order time accurate, noniterative, factored implicit finite-difference algorithm. The rotor deformation is described by a one-dimensional Green's function. The contact problem is solved by an iteration method so that the contact condition and the hydrodynamic bearing condition are satisfied simultaneously. The results show that the hydrodynamic bearing effect, especially the squeeze effect, is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the hydrodynamic bearing. A disagreement between the friction coefficient needed in the numerical analysis and the experimentally measured one in a previous study.     

Finite-element analysis of the rotor/stator contact in a ring-type ultrasonic motor

A way to understand mechanical characteristics of an ultrasonic motor is presented. First, the vibration mode of a stator is calculated using a finite-element method (FEM) code. The path of the elliptic motion of the stator's teeth is obtained. The computed vibration mode at the surface of the stator is compared with that measured by an electrooptical displacement transducer. Next, the contact condition of the rotor/stator is calculated. The displacement and velocity of the rotor/stator, the distortion of the stick/slip area, the rotational speed of the rotor, and the friction loss of the motor are obtained. The calculated rotor displacement and torque-rotational speed curve correspond closely to the experimentally measured ones. The internal loss of the rotor/stator and the loss of the supporting felt are measured. The total loss of these losses and the calculated friction loss agree with the measured total loss. The calculated and the measured efficiency of the motor also agree.     

The calculation of machine transient performance

In a recent paper the authors described the analysis of the transient field in the cross-section of a micro-generator during a field decrement test. Here results are presented for a similar calculation on a 4-pole 325 MVA machine. The complications arising from the conducting rotor body are discussed and suitable equations are formulated. A general transient machine formulation including stator currents is given.     

Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors

1. IntroductionA DVD spindle motor developed in this paper is atype of DC brushless motor with permanent magnet.The motor, with nine winding coils driven by a threephase witching circuit, has been widely used in diskdriver and shown an efficient and effective approachin the design process of spindle m.tors[1-4]. In thisresearch, a bonded NdFeB ring with BHm.. of 8-10MGOe, inner diameter of 20.1 mmt axial length of 6mm, and outer diameter of 22.4 mml are magnetizedwith 12 poles and used as…     

Capacitive sensor for relative angle measurement

Based on a capacitive angle and angular rate sensor, a sensor measuring the relative angle between two rotating shafts has been developed. Two rotatable electrodes are placed between two sensor plates. The relative angle between the two rotors and the absolute position of the rotor blades are calculated from measurements of the capacitive coupling between different transmitting stator segments and a single receiving electrode. A prototype of this sensor has been developed with a range of the relative angle of /spl plusmn/7.5/spl deg/ with a resolution of 0.1/spl deg/.