SR电机电压斩波方式电磁力分析

本文基于SR电机线性模型和定子振动简化模型 ,对SR电机 ,PWM运行方式下的切向力和径向力进行了仿真计算 ,对非能量回馈 (NERVC)和能量回馈 (ERVC)两种不同续流方式下切向力和径向力的大小进行了比较。本文研究对进一步开展SR电机振动抑制策略研究有较大意义。     

水平地震力作用下无铰圆弧拱桥平面挠曲振动方程的闭合解

对无铰圆弧拱桥，在水平地震力作用下，考虑阻尼力的影响时的平面挠曲振动方程进行了推导，并用Ｇａｌｅｒｋｉｎ法得出了一个实用的Ｄｕｈａｍｅｌ积分形式的公式     

加热区金属组织变化与加热切削深度的关系

本文通过等离子弧加热切削中金属表面软化层金相组织分析，来研究在一定加热条件下的切削深度，并提出４５＃和９ＳｉＣｒ两种淬火钢在一定加热条件下的合适切削深度。     

Lyapunov definition and stability of regular or chaotic vibration modes in systems with several equilibrium positions

This paper deals with forced vibrations of two-DOF systems with more than one equilibrium positions. Such systems may be obtained by digitization of elastic post-buckling systems. A vibration mode, which is periodic at small force amplitudes and becomes chaotic as the force amplitudes are slowly increased, is selected. It is possible to formulate and solve the problem of stability of a periodic or chaotic vibration mode in a space with greater dimension using the classical Lyapunov stability definition and some calculating procedures. Instability of phase trajectories is used as a criterion of the chaotic behavior in dynamical systems. Trajectories with very close initial values are compared. Use of the Lyapunov stability definition shows mutual stability/instability of the trajectories. Calculations permit to observe an appearance and enlargement of the chaotic behavior regions. Specific results are obtained for the nonautonomous Duffing equation and pendulum system.     

空调系统噪声控制技术

介绍空调系统噪声控制的措施,具有较大的实用意义.     

散斑检测技术及其应用

综述了散斑计量中的主要检测技术。主题包括散斑照相技术、散斑干涉技术、电子散斑干涉技术、数字散斑相关技术和时间序列散斑检测技术。介绍了散斑计量在科学和工程研究中的一些重要应用。     

阻尼复合材料舵板减振降噪试验研究

介绍了阻尼复合材料舵板的模拟试验情况,对阻尼复合材料舵板和金属舵板进行了水下振动和振动声辐射特性的对比试验分析,结果显示,在100Hz到5kHz范围内,水下辐射噪声前者比后者平均降低约7dB,表明该阻尼复合材料用于舰船的某些典型振动构件具有广阔前景。     

粘弹材料阻尼性能的分析模拟和预测

讨论了阻尼材料动态性能表征的数学模拟分析方法及其性能预测,从分数导数模型出发分析了阻尼材料动态性能内在的一些基本规律,为阻尼材料的研究、开发和性能测试提出了一些指导性的建议。     

逐孔爆破技术在金堆城露天矿的应用

介绍了以降低爆破震动为主要目标的逐孔爆破技术在金堆城露天矿的应用。利用SHOT PLAN软件进行爆破网路优化设计,实现了单孔单网路的可靠起爆。6次爆破震动测试结果表明,与原排间微差起爆技术相比,采用逐孔爆破技术后,爆破质点峰值振速降低了22%～78%。逐孔爆破技术的应用,有效降低了震动危害,使凹陷露天采场边坡的稳定得到了有效控制,同时改善了爆破效果,提高了铲装效率。     

Structural Damage Detection Using Empirical Mode Decomposition: Experimental Investigation

This paper presents an experimental investigation on the applicability of the empirical mode decomposition (EMD) for identifying structural damage caused by a sudden change of structural stiffness. A three-story shear building model was constructed and installed on a shaking table with two springs horizontally connected to the first floor of the building to provide additional structural stiffness. Structural damage was simulated by suddenly releasing two pretensioned springs either simultaneously or successively. Various damage severities were produced using springs of different stiffness. A series of free vibration, random vibration, and earthquake simulation tests were performed on the building with sudden stiffness changes. Dynamic responses including floor accelerations and displacements, column strains, and spring releasing time instants were measured. The EMD was then applied to measured time histories to identify damage time instant and damage location for various test cases. The comparison of identified results with measured ones showed that damage time instants could be accurately detected in terms of damage spikes extracted directly from the measurement data by EMD. The damage location could be determined by the spatial distribution of the spikes along the building. The influence of damage severity, sampling frequency, and measured quantities on the performance of EMD for damage detection was also discussed.