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971.
Frantz Rowe 《欧洲信息系统杂志》2006,15(3):244-248
972.
973.
MuShanxiang JiXiaoli LiMing LiXingguo 《电子科学学刊(英文版)》2003,20(6):407-413
Linear Modulated Frequency (LMF) Costas Stepped Frequency Radar (SFR) signal is introduced. Its ambiguity function is derived and analyzed in detail and its feasibility is validated in theory. The scheme of the proposed signal processing is also presented. The results of theoretic analysis and simulation show that, by using the proposed signal and increasing the bandwidth of the total stepped frequency, the ambiguity sidelobe is well suppressed and the range-velocity coupling in the stepped frequency radar is also greatly weakened. 相似文献
974.
ZhaoHongzhong ZhouJianxiong LiWeimin FuQiang 《电子科学学刊(英文版)》2003,20(6):401-406
High acceleration of radar targets is analyzed using Acceleration Ambiguity Function(AAF). The acceleration resolution based on AAF is defined. The AAF and acceleration resolution of rectangle pulse signal are derivated and the conclusion that its acceleration resolution is in inverse proportion with the square of its duration is drawn. In the end, these conclusions are applied to the parameter designing and performance evaluation for a certain type of pulse Doppler radar. 相似文献
975.
Summary
In this paper thermal behavior of some HNBR blends with CPE, PVC, CR and NBR at three temperatures, 150, 170 and 190°C is
presented. Changes in characteristic IR bands, gel fraction, and chlorine content were assessed. Some mechanistic differences
between the studied systems, regarding the involvement the depletion of chlorine and modification in gel content, were pointed
out. Cyclization of nitrile structure was also observed by means of 2240 cm−1 band ascribed to >C=NH. Kinetic considerations are presented.
Received: 3 June 2002/Revised version: 14 November 2002/ Accepted 20 November 2002
Correspondence to Traian Zaharescu 相似文献
976.
本文设计了一种应用于油气藏永久性实时动态监测系统。该系统用光纤Bragg光栅(FBG)传感器作为井下永久性传感器,测量目的层的温度、压力等参数的模拟信号;在井口建立数据采集处理系统,将模拟信号解调成数字信号;通过GPRS无线移动通信网络传输到监测中心的数据库服务器上,并以Web形式发布到Internet网络上,同时提供移动用户浏览接口,且当数据异常时可以发送报警短消息。该系统实现了油气藏的远程实时动态监测,可以为油藏管理人员和技术人员及时、准确地做出决策提供可靠依据。 相似文献
977.
978.
Sungho Jin 《Journal of Electronic Materials》2003,32(12):1366-1370
In packaging of microelectromechanical systems (MEMS), optical, and electronic devices, there is a need to directly bond a
wide variety of inorganic materials, such as oxides, nitrides, and semiconductors. Such applications involve hermetic-sealing
components, three-dimensional MEMS assembly components as well as active semiconductor or optical components, dielectric layers,
diffusion barriers, waveguides, and heat sinks. These materials are known to be very difficult to wet and bond with low melting-point
solders. New Sn-Ag- or Au-Sn-based universal solders doped with a small amount of rare-earth (RE) elements have been developed,
which now allow direct and powerful bonding onto the surfaces of various MEMS, optical, or electronic device materials. The
microstructure, interface properties, and mechanical behavior of the bonds as well as the potential packaging applications
of these new solder materials for MEMS and optical fiber devices are described. Various packaging-related structural, thermal,
or electrical issues in MEMS are also discussed. 相似文献
979.
Yanbin Luo Jianhui Zhang Alexandrov P. Fursin L. Zhao J.H. Burke T. 《Electron Device Letters, IEEE》2003,24(11):695-697
This letter reports the design and fabrication of 4H-SiC bipolar junction transistors with both high voltage (>1kV) and high dc current gain (/spl beta/=32) at a collector current level of I/sub c/=3.83A (J/sub c/=319 A/cm/sup 2/). An Al-free base ohmic contact has been used which, when compared with BJTs fabricated with Al-based base contact, shows clearly improved blocking voltage. A specific on-resistance of 17 m/spl Omega//spl middot/cm/sup 2/ has been achieved for collector current densities up to 289 A/cm/sup 2/. 相似文献
980.
小浪底水电厂位于多泥沙的黄河干流上,水轮机活动导叶会因磨损过大而严重漏水,在水轮机的设计上必须考虑这个因素;同时,为适应混水发电,小浪底水电厂机组采用了筒阀。文中介绍了筒阀的结构特点、功能及控制原理等,并对其在现场的实际应用情况进行了分析。 相似文献