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根据实际工程中风载作用下导线传给输电塔的荷载特征，利用随机参数结构受随机激励响应的模型，计算了输电塔脉动位移的统计值．     

汽车自动传动液减摩性能研究

采用改进的Falex-Ⅰ型摩擦磨损试验机考察了几种添加剂对汽车传动液的减摩特性影响．结果表明：2．6-二叔丁基对甲酚对汽车自动传动液的减摩性能影响较小，防锈剂、极压抗磨剂、分散剂、抗腐剂及摩擦改进剂等添加剂对油品的减摩性能影响较大；某些摩擦改进剂可以改善汽车自动传动液的摩擦稳定性；汽车自动传动液的减摩特性主要取决于添加剂的平衡关系及添加剂在金属表面的作用．     

架空输电线路塔架绝缘子串与导线风致作用模型研究

在风作用下塔架发生振动，通过悬挂绝缘子串作用在导线上。提出一种绝缘子串与导线相互作用的模型，并将模型结果与现场实测结果进行了对比分析。     

接触网输电导线动力响应分析的模态方法

对输电导线的动力特性作了分析，并用模态求出了其稳态响应     

The influence of variable stiffness of teeth on dynamic loads in single-gear transmission

Summary In this paper, the influence of the variable stiffness of mating gear teeth on dynamic loads occurring between teeth in a single-gear transmission is investigated using a discrete-continuous model consisting of two torsionally deformable ponderable shafts and four rigid bodies. The stiffness is described by a harmonic function of time. Considerations by means of the wave method enable to determine dynamic loads in steady as well as in transient states. Numerical calculations are concentrated on the determination of the amplitudes of dynamic loads on gear teeth with respect to revolution per minute. Received 4 March 1997; accepted for publication 12 September 1997     

Reflection and transmission in anisotropic dissipative multilayers

A planarly-stratified multilayer is considered with material properties depending on the Cartesian coordinate normal to the layers. Upon the assumption that the time dependence be harmonic, the equations of motion and the constitutive equations (of a viscoelastic solid) are given the form of a first-order system of ordinary differential equations. The propagator of the whole multilayer is determined and hence the reflection and transmission matrices are obtained for different boundary conditions. Next a new algorithm, which avoids some drawbacks of other procedures, is outlined. The reflection and transmission matrices of the multilayer are determined by recursive relations via the matrices, of reflection and transmission, associated with the single layers.     

沉淀对Al-Cu-Mg合金中锯齿形屈服现象影响及其微观实验研究

经固溶处理的Al-Cu-Mg合金在常应变率拉伸实验中具有显著的锯齿形屈服现象,且屈服行为随固溶处理温度的改变而呈现不同的特征。塑性变形特性与合金材料的微细观结构,尤其是位错运动的演化密切相关。本文运用透射电子显微镜,研究在不同温度下固溶处理的Al-Cu-Mg合金的微观结构,尤其是析出颗粒的大小和含量。并结合宏观的拉伸实验结果,分析Al-Cu-Mg合金动态应变时效的机制。     

Parameters influencing low frequency impact sound transmission in dwellings

As sound and vibration fields in dwellings exhibit modal behaviour at frequencies below 200 Hz, a systematic investigation of measurement and prediction uncertainty associated with impact sound transmission at low frequencies must include the effects of: location of the impact, type of floor, edge conditions, floor and room dimensions, room absorption and position of the receiver. Experimentally validated analytical models, described in a companion paper, have been used in an extensive investigation of impact sound transmission through rectangular homogeneous concrete floors and floating floors. The models were used to describe the effect of modal coupling and then to perform parametric and statistical studies aimed to identify the main factors affecting low frequency impact sound transmission.     

Vibro-acoustic behaviors of an elastically restrained double-panel structure with an acoustic cavity of arbitrary boundary impedance

An analytical study on the vibro-acoustic behaviors of a double-panel structure with an acoustic cavity is presented. Unlike the existing studies, a structural–acoustic coupling model of an elastically restrained double-panel structure with an acoustic cavity having arbitrary impedance on sidewalls around the cavity is developed in which the two dimensional (2D) and three dimensional (3D) modified Fourier series are used to represent the displacement of the panels and the sound pressure inside the cavity, respectively. The unknown expansions coefficients are treated as the generalized coordinates and the Rayleigh–Ritz method is employed to determine displacement and sound pressure solutions based on the energy expressions for the coupled structural–acoustic system. The effectiveness and accuracy of the present model is validated by numerical example and comparison with finite element method (FEM) and existing analytical method, with good agreement achieved. The influence of key parameters on the vibro-acoustic behaviors and sound transmission of the double-panel structure is investigated, including: cavity thickness, boundary conditions, sidewall impedance, and the acoustic medium in the cavity.     

Studies on the optical and dielectric properties of a zinc thiourea chloride NLO single crystal

Single crystals of a nonlinear optical material, zinc thiourea chloride were grown by the slow evaporation technique. The crystal structure and lattice parameters of the grown crystal were determined by the single crystal X-ray diffraction studies. The single crystal XRD revealed that the material crystallized in a orthorhombic crystal system. Optical studies were carried out and it was found that the tendency of transmission observed from the specimen, with respect to the wavelength of light, is practically more suitable for opto-electronic applications. The optical band gap is found to be 4.30 eV. Optical constants such as the band gap, refractive index, reflectance, extinction coefficient and real (?_r) and imaginary (?_i) components of the dielectric constant and electric susceptibility were determined from the UV–vis–NIR spectrum. The dielectric constant and dielectric loss of zinc thiourea chloride were measured in the different frequency range from 50 Hz to 5 MHz at different temperatures. Further, electronic properties, such as valence electron plasma energy, Penn gap, Fermi energy and electronic polarizability of the grown crystal have been estimated.