Temperature-dependent investigation of a high-breakdown voltage andlow-leakage currentGa0.51In0.49P/In0.15Ga0.85Aspseudomorphic HEMT

We reported a newly designed double delta-doped GaInP/InGaAs pseudomorphic HEMT with high temperature-dependent performances. In addition to the novel aspects of the proposed HEMT structure, temperature-dependent behaviors including a high-voltage (40 V) and a low-leakage current (17 nA/mm) are further improved by eliminating mesa-sidewall effect. We obtained nearly current-independent transconductance in the temperature of 300-450 K. The measured current gain cutoff frequency f_T and maximum oscillation frequency f _max for a 1-μm gate device are 12 and 28.4 GHz, respectively     

Spectral anomalies of diffracted Hermite-Gaussian beams in the neighborhood of focus

The spectral behavior of spatially coherent polychromatic Hermite-Gaussian (H-G) beams focused by an aperture lens is studied by using the propagation law of the cross-spectral density function. An analytical expression for the spectrum of focused H-G beams is derived, which is related to the original spectrum and spectral modifier, and the spectral modifier is dependent on the truncation parameter, Fresnel number, and position parameter. Detailed numerical results are given to illustrate the spectral anomalies of diffracted H-G beams in the neighborhood of focus.     

铜及铜合金表面改性研究的可行性

钢铁渗硫提高了钢铁零部体的自润滑性能，从而提高耐磨件寿命。从这一观点出发，分析铜及铜合金渗硫的可能性，改善铜及铜合金零件的耐磨性，延长部件寿命，把辉光放电渗硫这一新技术引用到铜及铜合金表面改性的研究。     

预裂爆破技术的发展

介绍了预裂爆破技术在美国、加拿大等国家工程爆破中的应用与发展以及我国在这方面的进展。     

柴油机气缸内局部瞬态碳粒浓度、火焰温度改进双色法测量系统

介绍了一套新的改进双色法柴油机气缸内局部瞬态火焰温度和碳粒浓度测试系统,其测试原理利用了颗粒的衍射理论,细致地考虑了柴油机缸内碳粒云的光学参数。测试系统中采用了分叉光纤从而省去了一套复杂的光学分光系统。新型的探头设计较好地解决了蓝宝石窗面的积炭问题,对测试系统进行了标定。在缸盖火力面上布置两个具有代表性的测点来测量火焰温度和碳粒浓度,测试结果表明：活塞凹坑部位火焰温度和碳粒浓度均较高;在活塞挤流区,循环变动很大。在活塞凹坑部位和活塞挤流区所测火焰温度和碳粒浓度均有一定相位差。     

燕化公司“全面能源管理”的经验

燕化公司在20余年能源管理的实践中,根据自身的生产特点,逐步摸索出了一条全员、全面、全过程节能管理经验,这对从传统的能源管理转向全面能源管理具有实际意义.     

Robust Frame Synchronization for Noisy PCM Systems

Serial digital transmission requires reliable frame synchronization at the receiver in order to demultiplex and recover the transmitted signals. This paper proposes a faster and more robust method of detecting frame synchronization. A large serial memory is used to store sufficient received history to include all bits of the synchronizing codeword. Equations have been developed which predict the search and "in frame" performance. These equations have been verified with laboratory models. Using, for example, the well-known D3 PCM system, the reframe time is improved from 48 to 3 ms. With an error rate of 1 percent, the predicted "in frame" time is improved from 1.9 s to several centuries! Techniques for hardware implementation are suggested and application to the extended framing format is discussed.     

江河风浪计算中的一些问题

讨论了江河堤防设计中波浪要素计算的一些问题，如计算风速选取，风区长度确定，波高统计分布等。基于实测风浪资料验证分析后认为：目前常用的计算方法，用于计算风向大致垂直于水流方向时是可行的；但当计算风向与水流方向大致平行时，计算结果误差甚大。     

广蓄电站高压管道排水系统布置

本文介绍广州抽水蓄能电站一期工程高压隧洞、高压岔管及高压引水钢支管的排水系统布置及其充水试验后的效果。