行星齿轮油膜浮动均载特性分析

用有限差分法求解二维Reynolds方程,得到了行星齿轮油膜压力分布、偏位角、偏心率的数值解;导出了油膜刚度表达式并给出了选取最佳半径间隙及计算均载系数的方法;分析了行星齿轮油膜浮动均载机构的特性及应用。     

下压轧制的斜轧穿孔轧辊开度分析

斜轧穿孔机轧辊开度计算是轧机工具设计和调整参数计算的基础。文中分析了下压轧制条件下二辊斜轧穿孔机的轧辊开度,并讨论了轧辊开度的非对称性对穿孔过程及毛管壁厚均匀性的影响。     

A Macro‐Damaged Viscoelastoplastic Model for Thermomechanical and Rate‐Dependent Behavior of Glassy Polymers

The primary objective of this paper is to develop a macro‐damaged viscoelastoplastic constitutive model to describe large deformation mechanical behavior for glassy polymers at various kinds of experimental conditions. First of all, quasi‐static and dynamic tension and compression tests were carried out to obtain stress–strain responses over wide range of rates and temperatures for two glassy polymeric materials, polymethylmethacrylate and polycarbonate. Then a phenomenological macroscopic damage model, covering effects of strain rates, temperatures, and effective strain, is incorporated into the constitutive model in the previous work. Furthermore, two distinct criteria are applied to predict the damage evolution affected by strain rate and temperature at elastic phase and plastic phase, respectively. The validations of the novel developed damaged model are made by the better matches with the testing data compared with the original undamaged model, and excellent agreements with the experimental result in all cases.

     

物联时代智能车载电子系统发展分析

智能车载电子系统既要满足苛刻的使用环境要求,又要集电脑、通信、导航等多种功能于一身,还要能与底层汽车电子系统进行通信,监控车辆运行状态。本文介绍了物联网络时代智能车载电子系统的技术特点、运行组织与运营模式,并根据我国宏观经济和汽车市场的发展,提出了具体的技术可行性实施案例,并进行了经济性分析,结论表明,智能车载电子系统将为整车企业、电信运营商、各类软硬件及内容提供商等公司带来巨大的增长点。     

Compression of pulse duration in a laser-diode, end-pumped, double Q-switched laser

By considering the Guassian transversal distribution of intracavity photon density and the longitudinal distribution of photon density along the cavity axis as well as the influence of the turn-off time of the acousto-optic Q switch, we introduce the coupled rate equations of a laser-diode, end-pumped, double Q-switched laser with an acousto-optic modulator and GaAs saturable absorber. In addition the thermal effect of the gain medium is taken into account. These coupled rate equations are solved numerically, and the dependence of pulse width on incident pump power at different pulse repetition rates is obtained for the generated output pulses. It is shown that the pulse duration is obviously shorter in contrast to the actively Q-switched Nd:YVO4 laser with an acoustic-optic modulator, and the maximum compression ratio of the pulse width is more than 60%. In the experiment a laser-diode, end-pumped, double Q-switched Nd:YVO4 laser with both an acousto-optic modulator and GaAs is realized, and the experimental results agree with the numerical solutions.     

Optimization of doubly Q-switched lasers with both an acoustic-optic Modulator and a Cr/sup 4+/-doped saturable absorber

By considering the Gaussian spatial distributions of the intracavity photon density and the initial population-inversion density as well as the influence of the acoustic-optic (AO) Q-switch, we provide the coupled rate equations for a doubly Q-switched laser with both an AO modulator and a Cr /sup 4+/ -doped saturable absorber (SA). These coupled rate equations are solved numerically. The key parameters of an optimally coupled doubly Q-switched laser are determined,and a group of general curves are generated for the first time. These key parameters include the optimal normalized coupling parameter, the optimal normalized SA parameters and the normalized parameters of the AO Q-switch, which can maximize the output energy. Meanwhile, the corresponding normalized energy, the normalized peak power and the normalized pulsewidth are given. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the SA, the AO Q-switch,the resonator and the spatial distributions of the intracavity photon density. Sample calculations for a diode-pumped Nd/sup 3/+:YVO/sub 4/ laser with both an AO modulator and a Cr/sup 4+/ :YAG SA are presented to demonstrate the use of the curves and the related formulas.     

Experimental and theoretical study of a laser-diode-pumped passively Q-switched intracavity-frequency-doubled Nd:GdVO4/KTP red laser with V:YAG saturable absorber

A laser-diode-pumped passively Q-switched intracavity-frequency-doubled Nd:GdVO4/KTP red laser with V:YAG saturable absorber is realized in a V-type resonator. The dependences of the pulse repetition rate, pulse width, single-pulse energy, and peak power on the incident pump power are measured and contrasted. By assuming the intracavity photon density and the initial population-inversion density to be Gaussian spatial distributions, the space-dependent rate equations of this laser are given. The numerical solutions of the rate equations are consistent with the experimental results. In order to optimize the described system, the variations of the pulse width, peak power, single-pulse energy, and laser efficiency with the initial transmission of the saturable absorber and the ratio of the laser beam radius to the pump beam radius are also calculated, respectively.     

模块UPS在图文中心信息机房的应用

阐述了模块UPS的技术特点,并结合实例,介绍了模块UPS在新图文信息中心信息机房中的应用。设计的系统简单实用、安全可靠,每台UPS的主输入和旁路输入都有独立的开关,提高了系统的可用度;可陆续扩容,节省首次投资;依据需要改善系统中性点接地电压,保证服务器的稳定运行。     

巡飞导弹区域巡逻侦察航迹规划研究

为了研究在岛屿、近岸作战区域等复杂战场环境下巡飞导弹区域巡逻侦察航迹规划问题,在威胁建模的基础上,将侦察航迹优化问题转化为最佳哈密顿圈问题,提出了基于Floyd算法和改良圈算法的航迹规划算法,并进行航迹修正得到可飞航迹.经仿真实验说明该航迹规划方法简单实用.     

Birefringence Characteristics of Squeezed Lattice Photonic Crystal Fibers

By using the supercell lattice method, we investigate the influence of the squeezing lattice on the birefringence characteristics of photonic crystal fibers (PCFs). We first define the concept of squeezing ratio and then present a model, with which several types of PCFs are simulated. Simulation results show that the squeezing of PCFs' lattice with the uniform air holes in the cladding can break the multifold symmetry of PCFs and make PCFs highly birefringent. Furthermore, it is reported for the first time to our knowledge that the polarity of PCFs' birefringence can change several times as the air-hole diameter changes.