Improvement of RCA transistor using RTA annealing after theformation of interfacial oxide

A polysilicon emitter RCA transistor (an ultra-thin interfacial oxide layer exists between polysilicon and silicon emitter) is presented which can operate at 77 K for the first time. An ultra-thin (1.5 nm) interfacial oxide layer is grown deliberately between polysilicon and silicon emitter using RCA oxidation and excellent device stability is obtained after rapid thermal annealing (RTA) treatment in nitrogen atmosphere. The RCA transistor exhibits good electrical performance at very low temperature for an emitter area of 3 × 8 μm². The maximum toggle frequency of a 1:2 static divider is 1.2 GHz and 732 MHz at 300 K and 77 K, respectively     

Thermodynamic modeling of native point defects and dopants of GaN semiconductors

A thermodynamic modeling of GaN was carried out to describe the thermodynamic behavior of native defects, dopants, and carriers (free electrons and holes) in GaN semiconductors. The compound energy model (CEM) was used. An unintentionally doped GaN was taken as an example. Oxygen was introduced into the model as the unintentionally doped impurity, according to the practical experimental phenomena. The energies of component compounds in the model were defined based on the results of the ab initio calculations and adjusted to fit experimental data. The thermodynamic properties of the defects and the oxygen doped were calculated to show the facility of the model.     

提高水平集方法初始化计算速度的研究

本文对水平集方法的初始化步骤进行了改进。在水平集方法中，初始化是一个很重要的步骤。它包括计算图像平面中每个点的初始水平集距离，同时找到与当前点距离最近的曲线上的点。这是一个费时的过程，影响到整个水个集方法的计算速度。本文基于快速推进法提出了一种快速初始化方法。这种方法只需要Ｏ（Ｎ）的时间就能够遍历所有的图像点，完成初始化。最后，对三种不同的初始化方法：直接法、快速推进法和本文的方法在计算速度上作了对比。实验表明，最终得到理想的分割结果的情况下，本文的方法在时间上优于其他两种方法。     

氨气提工艺尿素生产中操作的改进

中原大化集团公司尿素装置在操作上使用的是Ｓｎａｍ公司提供的尿素操作手册 ,在运行过程中 ,发现有许多地方与实际状况出入很大 ,经过不断的总结经验 ,并在工艺操作中进行改进、优化 ,使装置达到安全、稳定、经济运行的目的。1　二氧化碳压缩机操作方式的改进二氧化碳压缩机自开车以来 ,防喘振系统一直未投用。由于Ｓｎａｍ公司提供的防喘振曲线富裕度较大 ,操作人员对实际喘振点不清楚 ,正常生产中转速控制较高 ,操作盲目性很大 ,在 1 0 0 %负荷下 ,防喘振阀仍有 1 0 %左右的开度 ,造成蒸气消耗偏高。1 999- 0 3- 31 ,对二氧化碳压缩机各…     

国内电子商务门户网站的现状研究

从电子商务在我国迅速发展的角度出发，系统地介绍了我国电子商务网站的典范：阿里巴巴、淘宝。从电子商务的模式出发分析了其经营理念，成功因素及其不足，对中国的电子商务目前状况作了分析，并提出展望。     

船用低速五缸柴油机推进轴系扭振性能的改进与计算

国内的低速柴油机制造厂 ,船舶设计部门、造船厂和船东好象已经有一种共识 :艉机舱推进轴系使用低速五缸柴油机作主机时 ,都要用扭振减振器。但是 ,只要在设计时合理选用柴油机转速 ,并采用高强度低合金钢来制造中间轴 ,这类轴系大部分是不需要扭振减振器的。     

An EM‐based adaptive multiple target tracking filter

Tracking targets of interest is one of the major research areas in radar surveillance systems. We formulate the problem as incomplete data estimation and apply EM to the MAP estimate. The resulting filter has a recursive structure analogous to the Kalman filter. The advantage is that the measurement‐update deals with multiple measurements in parallel and the parameter‐update estimates the system parameters on the fly. Experiments tracking separate targets in parallel show that tracking maintenance ratio of the proposed system is better than that of NNF and RMS position error is smaller than that of PDAF. Also, the system parameters are correctly obtained even from incorrect initial values. Copyright © 2001 John Wiley & Sons, Ltd.     

单相开关磁阻电机及其控制

通过分析一种可以实现自启动的新型结构的永磁单相开关磁阻电机的基本工作原理，提出了一种性价比较高的控制方案，通过实验得出了结论。     

Laminated Reservoir Fracturing Technique

IntroductionOil production from laminated reservoirs is significant in Daqing Oilfield in the high water cut period. Hydraulic fracturing is a very efficient way to stimulate these laminated reservoirs. Daqing Oilfield is a multi-zone sandstone     

海河流域河道外生态需水研究

水土流失是海河流域较为突出的生态环境问题之一。经对比研究发现，植被覆盖度的变化会通过影响洪充量，土壤侵蚀量等因子，进而改变水土流失的状况。从提高植被覆盖度尤其是低覆盖度草地植被的角度出发，定量研究了为改善流域水土流失状况河道外生态需水的具体数额，得出海河流域现状年河道外生态耗水（降水）385亿m^3。另外，为改善河道外生态环境状况将低覆盖度草地提高地提高至中等覆盖度水平，则需要增加生态需水12．5亿m^3。