Structure, properties, and thermal stability of nanocrystallite Fe-Ti-N soft magnetic films

We deposited Fe-Ti-N magnetic films with a high sputtering power of 7 W/cm/sup 2/. When the composition of the films was in the range of Fe-Ti(3.9 at.%)-N(8.8 at.%) to Fe-Ti(3.3 at.%)-N(13.5 at.%), the films were composed of /spl alpha/' and Ti/sub 2/N precipitates. With the addition of nitrogen, 4/spl pi/M/sub s/ became higher than that of pure iron, reaching a maximum of 23.8 kG. At the same time, H/sub c/ was reduced to a minimum of 1.12 Oe. The best films can meet the needs of the recording head in dual-element giant magnetoresistive/inductive heads, yielding high storage density (10 Gb/in/sup 2/). The incorporation of N in /spl alpha/-Fe brought about the /spl alpha/' phase with its higher saturation magnetization. Ti additions inhibited the equilibrium decomposition /spl alpha/'/spl rarr//spl alpha/+/spl gamma/'. Because H/sub C//sup D//spl prop/D/sup 6/, where D is average grain diameter, grain size control is very important. The nitrogen induces severe distortion of the /spl alpha/' lattice, which can cause the grains to break into pieces and reduce the grain size. High sputtering power also led to the formation of fine grains, with diameter in the order of 14 nm. Probably Ti/sub 2/N is preferentially precipitated on the grain boundary, pinning the grain boundary and stabilizing the grain size during high-temperature heat treatment. The temperature limit for stability of the structure and its associated low coercivity was not less than 520/spl deg/C.     

数字化正弦平方脉冲信号

依据正弦平方脉冲的数学方程及其频谱分布，分别导出了与理想和标称视频带宽相对应的正弦平方脉冲的数学表达式及其编程生成方法。实验表明，此法不仅精确，而且便于修改参数，并可直接读人数字电视系统，来测定视频线性响应。     

基于压电陶瓷动态信息的结构裂纹识别方法

利用压电陶瓷的动态特性和压电系统的动态信息,对铝梁的裂纹损伤进行了分析研究。随着梁裂纹尺寸的增加,压电陶瓷片的导钠幅值下降,且系统固有频率减小。利用导钠幅值的变化和系统的动态信息,可以对裂纹的位置和尺寸大小进行识别。实验证明该方法的有效性。     

三相交流电动机启动过程参数数值模拟

提出一种进行模拟计算电动机启动过程中各参数的新方法。利用电机运行理论,结合物体定轴转动定律,推导出电机运行参数随时间变化的函数关系式。将计算公式离散化后,对电机启动过程运行规律进行求解。实例计算了一种型号潜油三相电动机启动时电动机定子电流、转子电流、激磁电流、扭转力矩、转速参数及效率参数等随时间或转差率的变化规律,其变化曲线与试验结果基本一致,说明提出的计算方法是有效、正确、适用的。     

一种宽带矢量调制器的设计及其应用

矢量调制器是一种可以同时控制微波信号幅度和相位的器件。本文介绍了一种基于新型微带定向耦合器的宽带矢量调制器。新的耦合器结构克服了传统微带耦合器耦合度低、方向性差的问题,也不需要Lange耦合器复杂的加工工艺,在平衡放大器、移相器和衰减器等场合具有广泛的应用。其次,研究了用串联电感对衰减器中PIN二极管的寄生参数进行补偿的一种简单方法,以改善衰减器衰减量变化时的相位性能。该方法原理简单,可在一定带宽内替代复杂的平衡结构,并给出相近的性能。最后给出了矢量调制器的测试结果和它在自适应天线阵等实际系统中的应用情况,并讨论了用于提高载波和边带抑制、满足高精度要求的校准方法。     

Fast handoff with reducing waste rate approach for wireless resources management in UMTS mobile networks

3G Wideband CDMA systems adopt the Orthogonal Variable Spreading Factor code tree as the channelization codes management for achieving high data rate transmission in personal multimedia communications. It assigns a single channelization code for each accepted connection. Nevertheless, it wastes the system capacity when the required rate is not powers of two of the basic rate. One good solution is to assign multiple codes for each accepted connection but it causes two inevitable drawbacks: long handoff delay and new call setup delay due to high complexity of processing with multiple channelization codes, and high cost of using more number of rake combiners. Especially, long handoff delay may result in more call dropping probability and higher Grade of Service, which will degrade significantly the utilization and revenue of the 3G cellular systems. Therefore, we propose herein an adaptive efficient codes determination algorithm based on the Markov Decision Process analysis approach to reduce the waste rate and reassignments significantly while providing fast handoff. Numerical results demonstrate that the proposed approach yields several advantages, including the lowest GOS, the least waste rate, and the least number of reassignments. Meanwhile, the optimal number of rake combiners is also analyzed in this paper. This research was supported in part by the National Science Council of Taiwan, ROC, under contract NSC-93-2213-E-324-018.     

稳压并抑制谐波的新型电源

由于电网谐波污染严重，对谐波的抑制已成为供电部门的重要任务。文章介绍一种既能稳压又能抑制谐波的新型电源，它采用串联型有源电力滤波的方法，通过瞬态电压补偿后可得到纯净的三相正弦平衡电压。     

反转构造的反转程度及其与油气聚集的关系

结合典型反转构造地震剖面，分析了断层型和褶皱型两类反转构造的反转程度，上下皆正断层型和向形褶皱型反转构造的反转程度轻微；上逆下正断层型和透镜形褶皱型反转构造的反转程度中等；上下皆逆断层型和背形褶皱型反转构造的反转程度强烈。分析了反转构造的反转程度与油气聚集的关系，处于轻微反转程度的上下皆正断层型反转和向形褶皱型反转，以及处于强烈反转程度的上下皆逆断层型反转和背形褶皱型反转不利于油气聚集；处于中等反转程度的上逆下正断层型反转和透镜形褶皱型反转类型有利于油气聚集成藏。     

我国道路石油沥青标准变更及产品生产应用的回顾

回顾我国50 a来道路石油沥青标准的变更及产品生产应用情况。随着我国炼制原油品种的增加和原油性质的改变及道路建设对沥青性能不断提高的要求,我国道路沥青标准也在不断的提高,目前的道路沥青标准已达到或接近国际先进水平。标准的提高,推动了沥青生产技术水平的提高,生产技术水平的提高满足了使用要求。     

深水海底泥浆举升钻井技术及其应用前景

为了解决深水钻井中遇到的问题，由Conoco公司领导的工业联合项目组研发了海底泥浆举升钻井（以下简称SMD）技术。采用该技术进行深水钻井时，隔水管内充满海水，泥浆用小直径管线从海底返回，在返回环空中形成两个压力梯度，实现双梯度控压钻井。文中着重介绍了SMD的理论依据、系统工作原理、系统关键设备以及SMD井控程序的HAZOP分析等。从技术适用性、经济性、装备以及可能存在的风险等方面对该技术在南中国海钻井中使用的可行性进行研究，并展望其应用前景。