苯甲酰甲酸甲酯的合成与应用

针对苯甲酰甲酸甲酯的合成工艺进行了分析,并对其应用进行了介绍。     

争做网络e少年

“国家计算机病毒应急处理中心在2003年元月25日下午通过监测发现互联网速度减慢,同时接到国家计算机网络应急响应协调中心的预警通知,在全球发现一种新型网络蠕虫病毒正在袭击全球计算机网络。并且,这种蠕虫病毒已经侵入我国计算机网络,已经造成部分网络阻塞、瘫痪。”……诸如此类的报道几乎已成了家常便饭,互联网在给我们带来便利的同时,也带来了很多危险。     

Study on Band Structure of YbB6 and Analysis of Its Optical Conductivity Spectrum

The electronic structure of YbB6 crystal was studied by means of density functional （GGA ＋ U） method. The calculations were performed by FLAPW method. The high accurate band structure was achieved. The correlation between the feature of the band structure and the Yb-B6 bonding in YbB6 was analyzed. On this basis, some optical constants of YbB6 such as reflectivity, dielectric function, optical conductivity, and energy-loss function were calculated. The results are in good agreement with the experiments. The real part of the optical conductivity spectrum and the energy-loss function spectrum were analyzed in detail. The assignments of the spectra were carried out to correlate the spectral peaks with the interband electronic transitions, which justify the reasonable part of previous empirical assignments and renew the missed or incorrect ones.     

基于改善整车加速噪声的试验及仿真方法

为了解决车辆在加速时发动机激励引起的车内噪声问题,进行了整车试验,得到噪声问题的主要频率特征。通过车辆加速时悬置被动侧振动加速度以及整车各个部件模态、振动灵敏度等数据确认了引起车内噪声的关键部件。首先,建立了整车有限元模型,仿真得到了关键部件模态;其次,通过试验验证了模型的有效性;然后,利用所建的整车模型对各部件进行改进,有效降低了各传递路径对车内噪声的灵敏度;最后,根据仿真结果提出了改进方案并进行装车验证。结果表明：车内的加速噪声主要由下拉杆悬置、副车架及前围板等部件与整车声腔模态耦合引起;改进后车内噪声明显改善,声压降低了8~9 dB。