地铁车辆永磁同步电机振动噪声测试及特性分析

为获得某地铁车辆永磁同步电机的噪声特性,开展了永磁同步电机的电磁力波理论分析和振动噪声测试,从A计权声压级、1/3倍频程和色谱图等指标分析不同测试工况与转速下的噪声特性。研究结果表明：永磁同步电机噪声主要由电磁振动产生,加速过程的主要频谱成分是48阶、56阶和104阶等阶次成分以及以开关频率及其倍频为中心的调制成分,减速过程无开关频率作用,其余阶次成分一致;电机在316 Hz、440 Hz和910 Hz等频率处存在局部模态,在电机阶次激励作用下易引发共振。振动噪声测试及特性分析可为永磁同步电机的应用提供指导。     

Ensemble deep transfer learning driven by multisensor signals for the fault diagnosis of bevel-gear cross-operation conditions

The existing intelligent fault diagnosis techniques of bevel gear focus on single-sensor signal analysis under the steady operation condition. In this study, a new method is proposed based on ensemble deep transfer learning and multisensor signals to enhance the fault diagnosis adaptability and reliability of bevel gear under various operation conditions. First, a novel stacked autoencoder(NSAE) is constructed using a denoising autoencoder, batch normalization, and the Swish activation function. Second, a series of source-domain NSAEs with multisensor vibration signals is pretrained. Third, the good model parameters provided by the source-domain NSAEs are transferred to initialize the corresponding target-domain NSAEs. Finally, a modified voting fusion strategy is designed to obtain a comprehensive result. The multisensor signals collected under the different operation conditions of bevel gear are used to verify the proposed method. The comparison results show that the proposed method can diagnose different faults in an accurate and stable manner using only one target-domain sample, thereby outperforming the existing methods.     

Design and experimental study of a compact quasi-zero-stiffness isolator using wave springs

Science China Technological Sciences - The quasi-zero-stiffness (QZS) vibration isolation has been proven to be an effective way to isolate low-frequency vibration. However, most of the existing...     

微波热处理对无托槽隐形正畸矫治器的力学性能影响

为探究微波热处理对无托槽隐形正畸矫治器的力学性能影响,对立体光固化(SLA)打印的标准试样件在不同功率的微波热处理后进行拉伸、弯曲力学性能测试,并通过3D偏差验证矫治器压膜工序前添加微波热处理工艺的有效性。结果表明,微波功率为400 W时,拉伸强度为50.6 MPa,提升了19.06%,断裂伸长率达到13.24%,弯曲强度为66.8 MPa,弯曲模量为2042 MPa;经过微波热处理的牙模压膜后在0.1 mm公差范围内的变形率降低了14.33%。微波热处理能够优化树脂制件的力学性能,并有效提高矫治器的制造精度。     

光电传感器式焊缝自动跟踪系统

采用点光源扫描的光电传感器对焊缝偏差进行检测,针对传感器的信号特点,提出了信号加权比较处理方法用于焊缝识别.建立了一种传感器旋转摆动的数学模型,对该模型进行了理论推导与分析,设计了一套模糊控制器,并采用MATLAB软件进行了仿真分析.开发了基于MSC-51单片机控制的硬件与软件.焊接试验表明,该系统跟踪精度高,工作稳定,成本低,满足实际生产应用要求.     

电液伺服系统的分数阶PID控制研究

针对三阶电液伺服系统,提出了一种新的PID控制器,把传统的PID控制器的阶次推广到分数领域,它不仅适用于分数阶系统,也适用于整数阶系统,并能取得一些优于整数阶PID控制器的效果.用滤波方法进行分数阶的微积分运算,直接求出传递函数,用Matlab/Simulink构造了PID模型,可直接在其它仿真系统中调用.仿真结果证明了该方法的正确性.     

A robust hybrid multi-criteria decision making methodology for contractor evaluation and selection in third-party reverse logistics

Due to green legislations, industries track the used products through reverse logistics contractors. A reverse logistics programme offers significant cost savings in procurement, transportation, disposal and inventory carrying. Since reverse logistics operations and the supply chains they support are considerably more complex than traditional manufacturing supply chains, it can be offered to third party contractors. But availability of more number of contractors make evaluating and selecting the most efficient Reverse Logistics Contractor (RLC) a challenging task and treated as a multi-criteria decision making problem. In this paper, a hybrid method using Analytical Hierarchy Process (AHP) and the Fuzzy Technique for Order Preference by Similarity to Ideal Solutions (TOPSIS) is proposed. AHP is used to obtain the initial weights and Fuzzy TOPSIS is used to get the final ranking. A case study demonstrates the application of the proposed method. Finally sensitivity analysis is carried out to confirm the robustness.     

大型塑料件注塑模浇注系统设计

利用模流分析软件Moldflow Plastics Advisers(MPA)对空调机面板注塑模6种构型不同的浇注系统分别进行注射成型流动分析。通过模拟空调机面板在一定成型材料、成型工艺条件下注射成型流动时的温度场、压力场、速度场,获得熔体流动前沿温度、实际注射时间、实际注塑压力、气穴位置、熔接痕位置等参数;在此基础上比较流动结果,预测空调机面板成型质量,确定最优的注塑模浇注系统设计参数,成功地解决了大型塑料件成型时可能出现的充模不足、熔接痕明显等质量缺陷,为模具设计提供了科学依据。     

空调机面板注塑模计算机辅助设计

运用Pro/E三维造型技术对空调机面板进行实体建模;运用Pro/E的MPA模块对注塑件注射成型流动进行数值模拟,获得了最佳浇口位置及浇口数量,优化了模具结构;运用Pro/E的外挂模块EMX自动创建模架、模具标准件、滑块、斜销等附件,对模具开模过程进行动态仿真和干涉检查。整个设计采用计算机参数化及全关联性数据库三维造型,提高了模具设计水平和效率,缩短了模具开发周期,降低了制造成本。     

乳液共混法制备水性阻尼涂料

通过乳液共混法将不同Tg的丙烯酸酯乳液进行共混,并加入填料和助剂配制成涂料。动态力学谱结果表明,当乳液按照丙烯酸乳液与苯乙烯-丙烯酸酯乳液比为40∶10共混时,阻尼温域得以拓宽,并达到Tg与室温一致的使用温域。