Self-excited vibration problems of maglev vehicle-bridge interaction system

The self-excited vibration problems of maglev vehicle-bridge interaction system were addressed, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the coupled model containing the quintessential parts was built, and the mechanism of self-excited vibration was explained in terms of energy transmission from levitation system to bridge. Then, the influences of the parameters of the widely used integral-type proportion and derivation（PD） controller and the delay of signals on the stability of the interaction system were analyzed. The result shows that the integral-type PD control is a nonoptimal approach to solve the self-excited vibration completely. Furthermore, the differential-type PD controller can guarantee the passivity of levitation system at full band. However, the differentiation of levitation gap should be filtered by a low-pass filter due to noise of gap differentiation. The analysis indicates that a well tuned low-pass filter can still keep the coupled system stable.     

轮胎在侧向力、纵向力联合工况下的神经网络模型

建立了轮胎在侧向力、纵向力联合工况下的神经网络模型，分析了不同训练方法对模型精度的影响。通过对轮胎实测值与神经网络预测值的对比表明，轮胎神经网络模型的精度能满足工程要求，BP前馈神经网络可有效地应用于车辆轮胎特性的数学建模。     

A practical robust nonlinear controller for maglev levitation system

In order to explore the precise dynamic response of the maglev train and verify the validity of proposed controller, a maglev guideway-electromagnet-air spring-cabin coupled model is developed in the first step. Based on the coupled model, the stresses of the modules are analyzed, and it is pointed out that the inherent nonlinearity, the inner coupling, misalignments between the sensors and actuators, and external disturbances are the main issues that should be considered for the maglev engineering. Furthermore, a feedback linearization controller based on the mathematical model of a maglev module is derived, in which the nonlinearity, coupling and misalignments are taken into account. Then, to attenuate the effect of external disturbances, a disturbance observer is proposed and the dynamics of the estimation error is analyzed using the input-to-state stability theory. It shows that the error is negligible under a low-frequency disturbance. However, at the high-frequency range, the error is unacceptable and the disturbances can not be compensated in time, which lead to over designed fluctuations of levitation gap, even a clash between the upper surface of electromagnet and lower surface of guideway. To solve this problem, a novel nonlinear acceleration feedback is put forward to enhancing the attenuation ability of fast varying disturbances. Finally, numerical comparisons show that the proposed controller outperforms the traditional feedback linearization controller and maintains good robustness under disturbances.     

空调方案优化与CAD

本文对常用制冷和空调方式的几个主要因素进行量化，提出因素权重系数概念，以反映空调方案设计阶段的客观条件和主观设计思想。运用计算机辅助设计，所选方案可行、优越     

提高变压器抗短路能力的措施

介绍了变压器短路的危害及工程中经常采用变压器抗短路能力的措施,在变压器的设计和制造过程中保证其具有足够的抗短路能力。     

基于Pro/E的远程零件参数化设计系统研究

提出了一种远程设计机械零部件的新方案.利用VC+ +对Pro/E进行二次开发,将开发的程序封装成COM组件,利用Pro/E进行参数化建模,通过ASP技术调用COM组件实现远程参数化设计.以斜齿圆柱齿轮为例说明机械零部件远程设计系统的实现过程.     

重型汽车非线性空气悬架控制策略对比研究

为改善重型汽车的行驶平顺性和道路友好性,基于重型汽车空气悬架的刚度特性,建立简化的重型汽车1/4车辆模型。对车身加速度和道路应力因子系数进行线性加权处理,并作为车辆的综合性能评价指标。设计了基于空气悬架系统的PID控制器、模糊控制器及混合天地棚控制器,对比分析了分别在低、中、高3种不同车速下,被动悬架与不同控制策略下空气悬架的车辆行驶平顺性、道路友好性及综合性能指数。结果表明,不同车速、不同控制策略对重型汽车行驶平顺性、道路友好性及综合性能的影响明显不同,混合天地棚控制策略下的空气悬架性能最优,其行驶平顺性、道路友好性及综合性能均优于PID控制策略和模糊控制策略。     

砷碱渣综合利用工艺及机理研究（英文）

砷碱渣是锑冶炼行业产生的固体废渣,对环境和人体健康构成严重威胁。目前,常见的砷碱渣湿法处理工艺不仅有价元素回收率低、砷碱分离不完全,还会产生砷碱混合盐,无法实现砷碱渣完全无害化处理。为解决这些问题,本文采用氧化水浸处理砷碱渣,实现了砷和锑的分离,砷、锑的浸出率分别为91.79%和0.62%,浸出渣可返回锑冶炼系统回收锑。通过碳热还原直接从砷碱混合盐(砷碱液蒸发结晶产物)中分离砷和碱,98.3%的砷可被脱除并制备成具有商业价值的无毒高纯金属砷,纯度达到99.9%;碱可从还原后渣中实现回收,良好地实现了砷碱混合盐的无害化和资源化处理。通过热力学、物相和砷价态分析研究了砷还原路径及挥发机理。     

新型相变储能材料研究进展

介绍了相变材料的种类、特点以及储能机理,重点论述了新型相变材料的研究发展,对于复合相变材料和胶囊化相变材料做了较为详细的说明,概括了相变材料的主要研究方向.     

基于谱图小波阈值的机床主轴振动数字信号降噪研究

通过数控机床运行过程中数据特征采集获得的实际信号存在噪声成分,无法根据信号特征判断机床实际运行状况。为了提高对特征参数提取对信号实施降噪能力,根据谱图小波转换理论与实际应用过程,构建了一种对一维数字信号分析的谱图小波阈值降噪（spectral wavelet threshold denoising, SWTD）算法,再通过仿真信号与机床主轴振动信号降噪方式验证了谱图小波阈值降噪可靠性。研究结果表明：机床主轴振动信号包含的有用频率基本都处于400 Hz范围内的低频区。完成降噪后,SWTD降噪信号形成了稳定幅值,已经接近初始信号,包络谱内超过400 Hz的高频段已被消除,形成了由主轴自转频率与滚切频率构成的主体成分,观察到明显主轴自转频率特征,表明该方法相对小波阈值降噪结果具备更优性能。