光电双基区晶体管(PDUBAT)的器件模型

本文在考虑了晶体管的小注入效应和大注入效应以及基区宽变效应等因素后,首次用近似和简化的数学表示式和相应的等效电路,描述了光电双基区晶体管(PDUBAT)负阻形成的机理并使负阻区和谷值区的理论计算和实验结果一致性很好.     

基于USB的数据采集系统设计及实现

讲述了一种基于USB的12b高速数据采集与信号分析系统的设计，设计中采用了FPGA(可编程逻辑器件)实现时序逻辑信号的控制，从而整个系统的设计具有很大的灵活性。该系统在Windows2000环境下的驱动程序及用户应用程序采用的是Visual C^ 语言实现的，而固件代码则是用C语言实现的。系统具有低成本、高性能的特点，能够广泛应用于测控、信号分析等多个领域。     

一种快速CRC 算法①的硬件实现方法

介绍了CRC校验算法的硬件电路实现方法。CRC校验广泛应用于通信、存储系统，在串行CRC实现的基础上，对电路结构提出了改进的方案，并实现了CRC的并行计算，由此进一步可以适用于任意位数据宽度的数据输入情况。     

鱼雷罐喷粉预处理过程水模研究

在鱼罐喷粉预处理水模实验数据的基础上，进一步利用线性回归确定各工艺操作参数对喷吹基本参数（均混时间、粉剂穿透比和粉剂停留时间）的影响，得出各传输动力学基本参数的函数关系式。     

浅谈黄土高原重点水土流失区的林业生态工程建设

黄土高原重点水土流失区林业生态工程建设的现状可以用“三低”（造林成活率低、保存率低、林木生长率低）来概括，人工林具有矮化，纤细，低产，烯疏4个特征，自然条件，适地适树、苗木质量、造林技术、抚育管护等5个方面的问题是造成“三低”的主要原因，适地适树适法是现阶段防治中造林“三低”的主要技术途径，其核心是“林水平衡”合理布局，适地适树，重视经济树种、抗旱造林以及加强病、虫、鼠、免、牛、羊、危害防治，是搞好区内林业生态建设的主要技术措施。     

恒运电厂5号机抽汽供热改造

介绍半高压单缸凝汽式汽轮机改造为抽汽拱热式组的设计思路及施工改造过程，对改造中出现的新问题进行了分析并提出解决办法，改造后，机组抽气直接供给热网，社会效益和经济效益明显。     

用边界元法提取VLSI版图电阻

介绍了ＶＬＳＩ版图验证中电阻提取的基本原理和主要方法，给出了一种新颖的基于边界元法的电阻提取算法。该算法采用变节点单元，较好地解决了实际问题中经常出现的角点问题。通过应用该算法对几个实例进行提取，证明使用本文的算法不仅在精度上而且在占用ＣＰＵ时间上都取得了令人满意的效果     

纤维共晶生长界面前沿三维扩散场解析

修正Ｊａｃｋｓｏｎ和Ｈｕｎｔ关于在垂直生长方向截面上溶质扩散各向同性假设，求解三维Ｌａｐｏｌａｃｅ方程，获得纤维共晶生长界面前沿三维稳态扩散场，并证明Ｊａｃｋｓｏｎ和Ｈｕｎｔ的二维模型是实际生长的二维简化和一阶近似，并用丁二腈（ＳＣＮ）一梓脑（ＣＡＭ）纤维共晶系统计算生长界面前沿溶质分布。     

Influence of gas composition on recurrence of atelectasis after a reexpansion maneuver during general anesthesia

BACKGROUND: Atelectasis, an important cause of impaired gas exchange during general anesthesia, may be eliminated by a vital capacity maneuver. However, it is not clear whether such a maneuver will have a sustained effect. The aim of this study was to determine the impact of gas composition on reappearance of atelectasis and impairment of gas exchange after a vital capacity maneuver. METHODS: A consecutive sample of 12 adults with healthy lungs who were scheduled for elective surgery were studied. Thirty minutes after induction of anesthesia with fentanyl and propofol, the lungs were hyperinflated manually up to an airway pressure of 40 cmH2O. FIO2 was either kept at 0.4 (group 1, n = 6) or changed to 1.0 (group 2, n = 6) during the recruitment maneuver. Atelectasis was assessed by computed tomography. The amount of dense areas was measured at end-expiration in a transverse plane at the base of the lungs. The ventilation-perfusion distributions (VA/Q) were estimated with the multiple inert gas elimination technique. The static compliance of the total respiratory system (Crs) was measured with the flow interruption technique. RESULTS: In group 1 (FIO2 = 0.4), the recruitment maneuver virtually eliminated atelectasis for at least 40 min, reduced shunt (VA/Q < 0.005), and increased at the same time the relative perfusion to poorly ventilated lung units (0.005 < VA/Q < 0.1; mean values are given). The arterial oxygen tension (PaO2) increased from 137 mmHg (18.3 kPa) to 163 mmHg (21.7 kPa; before and 40 min after recruitment, respectively; P = 0.028). In contrast to these findings, atelectasis recurred within 5 min after recruitment in group 2 (FIO2 = 1.0). Comparing the values before and 40 min after recruitment, all parameters of VA/Q were unchanged. In both groups, Crs increased from 57.1/55.0 ml.cmH2O-1 (group 1/group 2) before to 70.1/67.4 ml.cmH2O-1 after the recruitment maneuver. Crs showed a slow decrease thereafter (40 min after recruitment: 61.4/60.0 ml.cmH2O-1), with no difference between the two groups. CONCLUSIONS: The composition of inspiratory gas plays an important role in the recurrence of collapse of previously reexpanded atelectatic lung tissue during general anesthesia in patients with healthy lungs. The reason for the instability of these lung units remains to be established. The change in the amount of atelectasis and shunt appears to be independent of the change in the compliance of the respiratory system.     

简化源项计算方法

利用程序包STCP估算核电厂在发生严重事故情况下释放到环境的放射性源项需要耗费大量计算机时间和费用。所以,对所有感兴趣的事故情景完成源项程序包的计算实际上是不可能的。为此,发展了一个简化源项计算方法。它的基本思想如下:首先利用STCP计算几个选择的序列,然后根据放射性释放和事故进程的特点处理和分析由STCP计算得到的结果,得出一些特定参数,其它事故序列的源项能够通过这些参数的重新组合得到。