PERFORMANCE CHARACTERISTICS AND VISCOUS FLOW ANALYSIS OF CENTRIFUGAL PUMPS

ＰＥＲＦＯＲＭＡＮＣＥＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＡＮＤＶＩＳＣＯＵＳＦＬＯＷＡＮＡＬＹＳＩＳＯＦＣＥＮＴＲＩＦＵＧＡＬＰＵＭＰＳＰＥＲＦＯＲＭＡＮＣＥＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＡＮＤＶＩＳＣＯＵＳＦＬＯＷＡＮＡＬＹＳＩＳＯＦＣＥＮＴＲＩＦＵＧ...     

IMPROVEMENTS ON THE CONFIGURATION AND OPTIMUM PARAMETERS OF HIGH一SPEED THRUST BEARINGS

ＩＭＰＲＯＶＥＭＥＮＴＳＯＮＴＨＥＣＯＮＦＩＧＵＲＡＴＩＯＮＡＮＤＯＰＴＩＭＵＭＰＡＲＡＭＥＴＥＲＳＯＦＨＩＧＨ一ＳＰＥＥＤＴＨＲＵＳＴＢＥＡＲＩＮＧＳＩＭＰＲＯＶＥＭＥＮＴＳＯＮＴＨＥＣＯＮＦＩＧＵＲＡＴＩＯＮＡＮＤＯＰＴＩＭＵＭＰＡＲＡＭＥＴＥＲ...     

IMPROVING ACCURACY OF CNC MACHINE TOOLS THROUGH COMPENSATION FOR THERMAL ERRORS

ＩＭＰＲＯＶＩＮＧＡＣＣＵＲＡＣＹＯＦＣＮＣＭＡＣＨＩＮＥＴＯＯＬＳＴＨＲＯＵＧＨＣＯＭＰＥＮＳＡＴＩＯＮＦＯＲＴＨＥＲＭＡＬＥＲＲＯＲＳＬｉＳｈｕｈｅＺｈａｎｇＹｉｑｕｎＹａｎｇＳｈｉｍｉｎＺｈａｎｇＧｕｏｘｉｏｎｇＴｉａｎｊｉｎＵｎｉｖｅｒｓｉｔ...     

RECOGNITION OF STRUCTURAL DIAGRAM OF MACHINE TOOL SPEED CHANGE SYSTEM WITH ANY COMPOSITE RATIO

ＲＥＣＯＧＮＩＴＩＯＮＯＦＳＴＲＵＣＴＵＲＡＬＤＩＡＧＲＡＭＯＦＭＡＣＨＩＮＥＴＯＯＬＳＰＥＥＤＣＨＡＮＧＥＳＹＳＴＥＭＷＩＴＨＡＮＹＣＯＭＰＯＳＩＴＥＲＡＴＩＯＲＥＣＯＧＮＩＴＩＯＮＯＦＳＴＲＵＣＴＵＲＡＬＤＩＡＧＲＡＭＯＦＭＡＣＨＩＮＥＴＯＯＬＳ...     

INVESTIGATION INTO THE DEGRADATION OF CUTTING FLUIDS IN A WORKSHOP ENVIRONMENT

ＩＮＶＥＳＴＩＧＡＴＩＯＮＩＮＴＯＴＨＥＤＥＧＲＡＤＡＴＩＯＮＯＦＣＵＴＴＩＮＧＦＬＵＩＤＳＩＮＡＷＯＲＫＳＨＯＰＥＮＶＩＲＯＮＭＥＮＴＳｕｌｉｍａｎＳＭＡ，ＮａｂｈａｎＭＢ，ＵｎｉｖｅｒｓｉｔｙｏｆＢａｈｒａｉｎ，ＡｂｕｂａｋｒＭＩ，ＡｍｅｒｉＣｏ...     

PREDICTION OF MICROSTRUCTURE EVOLUTION DURING HOT EXPANDING-EXTRUSION FORMING OF RESTRAINING RINGS

ＰＲＥＤＩＣＴＩＯＮＯＦＭＩＣＲＯＳＴＲＵＣＴＵＲＥＥＶＯＬＵＴＩＯＮＤＵＲＩＮＧＨＯＴＥＸＰＡＮＤＩＮＧＥＸＴＲＵＳＩＯＮＦＯＲＭＩＮＧＯＦＲＥＳＴＲＡＩＮＩＮＧＲＩＮＧＳＬｉｕＪｉａｎｓｈｅｎｇＣｈｅｎＨｕｉｑｉｎＧｕｏＨｕｉｇｕａｎｇＴａｉｙ...     

STUDY ON USING SERIAL PIPE TO IMPROVE THE DYNAMIC RESPONSE OF ELECTRO－HYDRAULIC SPEED CONTROL SYSTEM

ＳＴＵＤＹＯＮＵＳＩＮＧＳＥＲＩＡＬＰＩＰＥＴＯＩＭＰＲＯＶＥＴＨＥＤＹＮＡＭＩＣＲＥＳＰＯＮＳＥＯＦＥＬＥＣＴＲＯ－ＨＹＤＲＡＵＬＩＣＳＰＥＥＤＣＯＮＴＲＯＬＳＹＳＴＥＭＳＴＵＤＹＯＮＵＳＩＮＧＳＥＲＩＡＬＰＩＰＥＴＯＩＭＰＲＯＶＥＴＨＥＤＹＮＡＭ...     

REGULARITY OF VIBRATION RESPONSE OF MECHANICAL SYSTEM UNDER AFFECT OF VARI-FREQUENCY EXCITING FORCE

ＲＥＧＵＬＡＲＩＴＹＯＦＶＩＢＲＡＴＩＯＮＲＥＳＰＯＮＳＥＯＦＭＥＣＨＡＮＩＣＡＬＳＹＳＴＥＭＵＮＤＥＲＡＦＦＥＣＴＯＦＶＡＲＩ－ＦＲＥＱＵＥＮＣＹＥＸＣＩＴＩＮＧＦＯＲＣＥＲＥＧＵＬＡＲＩＴＹＯＦＶＩＢＲＡＴＩＯＮＲＥＳＰＯＮＳＥＯＦＭＥＣＨＡＮＩ...     

PREDICTION OF PUMP CHARACTERISTICS ACCORDING TO GEOMETRICAL PARAMETERS OF IMPELLER AND VOLUTE CASING

ＰＲＥＤＩＣＴＩＯＮＯＦＰＵＭＰＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＡＣＣＯＲＤＩＮＧＴＯＧＥＯＭＥＴＲＩＣＡＬＰＡＲＡＭＥＴＥＲＳＯＦＩＭＰＥＬＬＥＲＡＮＤＶＯＬＵＴＥＣＡＳＩＮＧＰＲＥＤＩＣＴＩＯＮＯＦＰＵＭＰＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＡＣＣＯＲＤ...     

CONSTRUCTION DESIGN AND FLOW ANALYSIS OF CENTRIFUGAL PUMP IMPELLER WITH SUPER-LOW SPECIFIC SPEED

ＣＯＮＳＴＲＵＣＴＩＯＮＤＥＳＩＧＮＡＮＤＦＬＯＷＡＮＡＬＹＳＩＳＯＦＣＥＮＴＲＩＦＵＧＡＬＰＵＭＰＩＭＰＥＬＬＥＲＷＩＴＨＳＵＰＥＲＬＯＷＳＰＥＣＩＦＩＣＳＰＥＥＤ①ＹａｎｇＭｉｎｇｕａｎＹｕａｎＳｈｏｕｑｉＣａｏＷｕｌｉｎｇＪｉａｎｇｓｕＵｎｉ...     

一种改进的ARMA模型参数估计方法

针对自回归滑动平均(auto-regressive moving average,简称ARMA)模型参数谱估计容易出现谱峰漂移问题,提出一种基于组合目标函数和遗传算法的ARMA模型参数估计方法.通过最小均方误差准则获得ARMA模型参数初始估计,依据现代谱估计理论和连续函数极值存在的必要条件推导模型参数的频域约束方程,构造组合目标函数并采用遗传算法对模型参数初始估计值进行优化获得模型参数的最优解.将该方法用于车削状态下尾顶尖垂直方向振动加速度时间序列建模和谱估计,结果表明了方法的有效性.     

ARMA Modelling for Whispered Speech

The Autoregressive Moving Average (ARMA) model for whispered speech is proposed. Compared with normal speech, whispered speech has no fundamental frequency because of the glottis being semi-opened and turbulent flow being created, and formant shifting exists in the lower frequency region due to the narrowing of the tract in the false vocal fold regions and weak acoustic coupling with the subglottal system. Analysis shows that the effect of the subglottal system is to introduce additional pole-zero pairs into the vocal tract transfer function. Theoretically, the method based on an ARMA process is superior to that based on an AR process in the spectral analysis of the whispered speech. Two methods, the least squared modified Yule-Walker likelihood estimate (LSMY) algorithm and the Frequency-Domain Steiglitz-Mcbride (FDSM) algorithm, are applied to the ARMA model for the whispered speech. The performance evaluation shows that the ARMA model is much more appropriate for representing the whispered speech than the AR model, and the FDSM algorithm provides a more accurate estimation of the whispered speech spectral envelope than the LSMY algorithm with higher computational complexity.     

基于混合优化策略的自回归-滑动平均模型建模

自回归一滑动平均(ARMA)模型参数估计一直是ARMA模型建模问题的难点和重点,目前的模型参数估计方法都采用传统最小二乘法及其推广算法,预测精度低.采用基于混合优化策略的遗传模拟退火算法进行ARMA模型参数估计,克服了传统算法的缺点,并在此基础上利用遗传模拟退火算法可以确定ARMA阶次的特点,提出基于混合优化策略的ARMA模型建模方法.利用这种建模方法和传统建模方法对组合炮控系统精度进行建模比较,证明基于混合优化策略的ARMA模型建模方法收敛快,精度高.     

多维时序可控模型的建模

研究多维可控自回归滑动平均模型的建模问题，提出了ＣＡＲＭＡＶ模型参数的线性估计法，过渡矩阵的引用使建模速度和运算工作量得到较大改善，同时还讨论了模型参数的剔除处理及模型参数的适用性检验准则。     

二维ARMA模型及其在钢板形貌功率谱估计中的应用

二维ＡＲＭＡ模型的参数估计中,由于其对应的二维修正Ｙｕｌｅ－Ｗａｌｋｅｒ方程不具备唯一性和可辩识性,使得二维ＡＲＭＡ模型的定阶计算参数估计一直是一个非常困难的问题。本文正是针对该点,提出了一种二维ＡＲＭＡ模型的初步定阶方法,同时对ＡＲ参数的自相关函数估计方法进行了改进,在此基础上得到了功率谱估计算法。该算法在文中的应用实例中表现出了非常高的分辨率,另外在钢板表面形貌的功率谱估计中也得到了非常好的效果。     

基于递推最小二乘法与模糊自适应扩展卡尔曼滤波相结合的车辆状态估计

针对汽车状态估计中模型参数的变化和观测噪声的时变特性,提出了递推最小二乘法与模糊自适应扩展卡尔曼滤波相结合的汽车状态估计算法。为实现模型参数与观测噪声的实时更新,建立了基于三自由度非线性车辆动力学模型的算法,首先利用递推最小二乘法对汽车的总质量进行估计,其次建立了模糊控制器对扩展卡尔曼滤波的观测噪声进行实时跟踪。在搭建的CarSim与MATLAB/Simulink联合仿真平台中验证了该算法的有效性,结果表明该算法估计精度高于传统扩展卡尔曼滤波算法,研究结果为汽车的主动安全控制提供了理论支持。     

自适应SA-PSO优化的威布尔混合分布参数估计方法及应用

针对采用传统参数估计方法得到的模型拟合误差较大的问题，建立多重威布尔混合分布参数估计的非线性最小二乘模型，并提出基于模拟退火（SA）思想的自适应粒子群（PSO）算法进行求解。在PSO算法优化过程中，采用自适应方法调整惯性权重和加速因子，加快其收敛速度；引入模拟退火机制，根据Metropolis准则确定最优粒子的取舍，改善其全局搜索能力。将该方法应用到某型柴油机喷油器失效分布的参数估计中，并与图解法、基于Levenberg-Marquardt的非线性最小二乘法、标准PSO算法、自适应PSO算法求解的结果进行比较，分析所提方法的优化性能及精度。结果表明，该方法能够有效提高多重威布尔混合分布模型参数估计的精度和效率。     

PARAMETRIC IDENTIFICATION OF PARALLEL MANIPULATOR WITH REDUNDANCY DRIVEN BY PNEUMATIC MUSCLES

A new parameter estimation algorithm is proposed for parametric identification of a parallel manipulator driven by pneumatic muscles with redundancy. Due to the special physical properties of the parallel manipulator studied, the regression model for parametric identification is characterized by multieollinearity, which will result in unreliable and inaccurate parameter estimations with large eovarianee if the conventional parameter estimation algorithm based on single error minimizing criterion is used. To improve the quality of parameter estimation and achieve high precise posture trajectory tracking control of the parallel manipulator, a new parameter estimation algorithm based on composite error minimizing criterion is developed in need of theoretical contractive forces of pneumatic muscles. The experimental results indicate that the proposed algorithm integrated with adaptive robust control could provide reliable parametric identification and greatly enhance the control accuracy in the trajectory tracking control of the parallel manipulator, and that the variation of known theoretical contractive forces of pneumatic muscles has slight influence on the control performance.     

基于改进人工蜂群算法的机车车辆关键零部件可靠性研究

针对我国机车车辆现行检修制度中可能存在的过修、欠修问题,提出了一种综合图解法和改进人工蜂群(ABC)算法的机车车辆关键零部件可靠性模型拟合方法,对三参数威布尔分布进行参数估计并确立三参数威布尔可靠性模型。首先利用图解法求得三参数威布尔分布参数的初始估计值以及ABC算法的搜索空间,随后运用改进ABC算法进行迭代计算以获得较优的参数估计值,最后将可靠性模型拟合方法与最小二乘法以及概率加权矩法进行分析比较。研究结果表明,提出的可靠性模型拟合方法能够较为准确地确定三参数威布尔可靠性模型。以该模型为基础对机车车辆关键零部件进行可靠性指标计算,为决策人员确定机车车辆最佳维修周期和改进检修规程提供了科学依据。     

基于遗传算法的ARMA模型定阶新技术

针对时间序列分析与预测中最为常见的ARMA模型的定阶问题,在分析传统定阶方法缺点的基础上,提出了用遗传算法确定ARMA(n,m)模型的自回归阶数n和滑动平均阶数m的新方法。首先由ARMA模型的预测值与实测值定义平均相对变动值(Average relative variance,ARV),并根据其建立遗传算法的适应度函数;然后选取适当的种群数、交叉效、变异率及进化代数;通过逐代进化,得到最优的ARMA模型。最后,通过太阳黑子数据验证了基于遗传算法的ARMA模型定阶新技术的有效性和实用性。