工科线性代数流行教材的失误及修改意见

近年讲授工科线性代数，发现流行教材普遍存在一些失误，有的还很严重．为减少其不良影响，本文特提出若干修改意见．供讲课教师和教材编者参考．     

厚金属靶在弹丸打击下的侵彻与穿透

 给出了预测厚金属靶在不同形状弹头弹丸大速度范围内打击下侵彻与穿透的简单分析方程。在方程的建立过程中，假定变形是局部化的、冲击能量仅由侵彻过程吸收，并进一步假定靶材料对弹丸的平均阻（压）力由两部分组成：一部分基于空穴膨胀理论由于靶材料弹-塑性变形所产生的准静态凝聚阻力；另一部分是考虑了速度效应后的动压力。推导出了预测靶侵彻深度和弹道极限的方程表达式，并与金属靶在不同形状弹头弹丸大速度范围内打击下侵彻与穿透的实验进行了比较。理论预测与实验结果吻合得很好。     

计算机及数学软件在高职数学教学中的应用

阐述了计算机与数学软件运用于高等职业教育数学教学中的设想与实践探索．把数学实验作为传统教学、计算机和数学软件相结合的一种实践,贯穿于日常的教学过程,并列举了对应的课堂教学具体实例加以展示．最后指出,高职数学教学中应该加强这种教学模式的设计和开发．     

亚100 nm应变Si/SiGe nMOSFET阈值电压二维解析模型

本文基于二维泊松方程,建立了适用于亚100 nm应变Si/SiGe nMOSFET的阈值电压理论模型.为了保证该模型的准确性,同时考虑了器件尺寸减小所导致的物理效应,如短沟道效应,量子化效应等.通过将模型的计算结果与二维器件模拟器ISE的仿真结果进行对比分析,证明了本文提出的模型的正确性.最后,还讨论了亚100 nm器件中常规工艺对阈值电压的影响.该模型为亚100 nm小尺寸应变Si器件的分析设计提供了一定的参考. 关键词： 亚100nm 应变Si/SiGe nMOSFET 二维表面势 阈值电压     

丁苯接枝的高乙烯基聚丁二烯橡胶合成及其与丁苯橡胶的相容性研究

以n-BuLi为引发剂,THF为结构调节剂合成一定分子量和苯乙烯结构单元含量的丁苯大分子(SB).在SB的加氢汽油溶液中用Mo-Al(正辛醇取代的MoCl5和Al(OPhCH3)(i-Bu)2)催化丁二烯配位聚合制备丁苯接枝的高乙烯基聚丁二烯橡胶(SB-grafted HVPBR).接枝结构是通过聚丁二烯活性链与SB分...     

某型接收机后级放大器的设计

介绍了后级放大器的设计方法,放大器要求在1GHz带宽内增益平坦度≤±0.3dB,功率输出1dB压缩点≥8dBm.文中介绍应用ADS软件进行了电路设计和仿真,电路制版后装配调试.测试结果和仿真进行比较,指标满足设计要求.     

Calculation of infrared properties of low emissivity coatings containing metallic flake pigments

The infrared emissivity of low emissivity coating can be significantly reduced by adding high content concentrations of parallel distributed metallic flake pigment. However, the infrared emissivity is very difficult to calculate by the existing theory models, such as the light scattering theory and traditional Kubelka-Munk radiative transfer model, because of shape and distribution anisotropy of flake pigments. Thus, the low emissivity coating is assumed to be the superposition structure of homogeneous layers and metallic flakes are approximately uniform and parallel arrangement in each layer. Based on geometric optics theory and Kubelka＇s layer model, considering multiple reflection, transmission and absorption of infrared radiation among different layers, the theoretical model is established to calculate the coating emissivity. The facts of binder, pigment concentration and thickness are also systematic discussed. The result shows that the law of influence on infrared emissivity can be correctly simulated by this theoretical model. Transparent binder, high volume concentration of thin flake pigment can facilitate to reduce infrared emissivity. Moreover, this model offers the possibility of predicting the infrared optical properties of coatings by their optical constants.     

太赫兹脉冲技术及其在宽带示波器计量方面的研究

介绍了太赫兹脉冲技术在宽带示波器计量校准方面的应用。首先介绍了宽带示波器上升时间和带宽的校准原理,然后介绍基于光电技术的太赫兹脉冲的产生和测量技术,最后利用实验室现有的条件对50GHz和70GHz取样示波器上升时间进行了校准,测试结果表明用该方法产生的太赫兹脉冲是校准宽带示波器的有效方法之一。     

Mssbauer studies on the shape effect of Fe_(84.94)Si_(9.68)Al_(5.38) particles on their microwave permeability

Ball milling for long time (such as 10, 20, and 30 h) can transform Fe 84.94 Si 9.68 Al 5.38 alloy powders with irregular shapes into flakes. X-ray diffraction (XRD) and Mssbauer measurements have proven that the unmilled particles and the flakes obtained by milling for 10 h have the same D0 3 -type superlattice structure. The flakes obtained by milling for 20 h and 30 h have the same disorder α-Fe(Si, Al) structure. There are more than 6 absorption peaks in the transmission Mssbauer spectra (TMSs) for the particles with D0 3 -type superlattice structure, which can be fitted with 5 sextets representing 5 different Fe-site environments. However, only 6 TMS absorption peaks have been found for particles with a disorder α-Fe(Si, Al) structure, which can be fitted with the distributions of Mssbauer parameters (Bhf, isomer shift). The TMS results show that the flaky particles have a stronger tendency to possess the planar magnetic anisotropy. As the result, the flakes have larger microwave permeability values than particles with irregular shapes. The conversion electron Mssbauer spectra (CEMSs) also show the significantly different Fe-sites environments between the alloy surface and the inside.