Study on Microwave Dielectric Property of Carbon Black and Short Carbon Fibers

Carbon black and carbon fibers of different lengths were introduced in different matrices at different ratios to explore their microwave dielectric properties under 8.2 GHz-12.4 GHz. It is found that the actual dielectric constants of the samples containing carbon black are in a two-order function of the contents of carbon black （ε＇, ε＂=Av2＋Bv＋C） and the complex dielectric constants show an obvious frequency response. Of the added fibers of different lengths, the 4 mm-long one could well disperse in the matrices having not only good frequency response, but also larger real parts, imaginary parts and loss values. The imaginary parts and the loss values （tanδ）of the samples with 4 mm-long carbon fibers added increase linearly with the contents of fiber increasing. So it is practicable to adjust the dielectric parameters of the material in a wide range by changing the added amount of carbon black, and the carbon fiber or altering the lengths of the carbon fiber added.     

镗削声发射信号与镗刀磨损量关系的研究

 对镗削过程中声发射信号与刀具磨损之间的关系进行了实验研究和理论分析,得到了声发射信号的特征量与刀具磨损量之间的关系。本文提出用声发射信号随时间变化的记录长度内最大峰值电压V_(pmax)对时间f的累积均值(?)及累积均方差σ_t为在过程(In-Process)实时辨识镗刀磨损的特征量,以便实现刀具磨损的预报控制。     

多点喷射贫预混喷嘴流场及排放特性研究

基于燃料喷射孔与旋流器中空叶片相耦合的发展趋势和避免贫预混喷嘴发生回火和自燃,本文提出了一种新型的带收敛出口、壁面开冷却孔且中空叶片叶背开喷射孔的多点喷射贫预混喷嘴,采用试验研究了其流场和污染排放特性,并采用数值计算对流场和燃料/空气混合特性进行了补充研究。结果表明：主回流区脱离喷嘴出口一段距离,有利于产生脱体火焰而防止发生自燃和回火,且本文喷嘴出口温度监测结果也证实了在喷嘴内未发生自燃和回火;不同压力状态下喷嘴出口截面混合不均匀度SMV（Spatial Mixing Variance）均在4.7%左右,满足低污染燃烧室SMV低于5%的要求;并且污染物排放试验结果表明贫预混喷嘴能同时满足NOx和CO排放要求(@ 15% O2)的Φdome范围较宽,为0.65-0.82,能减少其应用在全环燃烧室的分级数,另外当Φdome低于0.70时,贫预混喷嘴的NOx排放低于10ppmv(@ 15% O2)。本文提出的新型贫预混喷嘴能满足燃气轮机低污染排放要求。     

定向能武器及其应用

介绍了未来战争中的一种重要武器———定向能武器,包括激光武器、粒子束武器和射频武器。概述了这三种武器的工作机理、主要特点并进行了相互比较,介绍了定向能武器的应用。     

φ50毫米微波测速系统

本文叙述了在50毫米二级轻气炮发射管内采用的微波反射技术:当模型运动的时候,将射入炮管内的微波和从模型上反射的微波间的相位变化记录下来,便可以获得炮管中模型运动速度的连续测量。     

星载L波段宽带低噪声放大器芯片设计

基于0.25μm 砷化镓赝品高电子迁移率晶体管（GaAs pHEMT）工艺，设计了一款应用于星载微波接收机的L波段单片微波集成电路（MMIC）低噪声放大器（LNA）。该低噪声放大器采用电流复用拓扑结构，降低了芯片的工作电流，节省了宝贵的卫星能量资源；通过两级负反馈方式优化了器件的稳定性和增益平坦度，提高了卫星通信质量；恒流源的偏置结构使得工作电流随工艺波动较小，芯片维持在稳定的工作状态下。测试结果表明：该放大器工作电流为35mA，在频率范围0.9~1.8GHz内，增益大于33dB，噪声系数小于0.6dB，增益平坦度小于0.5dB；芯片尺寸为2.0mm×1.3mm，满足航天产品的高性能小型化应用需求。     

军用设备电磁发射测试项RE102的实现CSCD

电磁兼容性(EMC)是指设备或系统在电磁环境中符合要求运行并不对其环境中的其它设备产生影响的电磁干扰的能力。因此,EMC包括两个方面的要求:一方面是指设备在正常运行过程中对所在环境产生的电磁干扰不能超过一定的限值,即电磁干扰度(EMI);另一方面是指设备对所在环境中存在的电磁干扰具有一定程度的抗扰度,即电磁敏感度(EMS)。本文描述符合《GJB 152A-97军用设备和分系统电磁发射和敏感度测量》要求的"RE102 10kHz^40GHz电场辐射发射"实现方法。     

On the motions of RHESSI flare footpoints

The footpoint motions of flare hard X-ray (HXR) sources are directly related to the reconnection scenario of a solar flare. In this work, we tried to extract the information of footpoint motions for a number of flares observed with RHESSI. We found that the RHESSI flare results of the footpoint motions strongly support the classification proposed from the observations of YOHKOH/HXT. Furthermore, it is found that a flare can consist of two types of footpoint motions. We discussed the connections of the footpoint motions with the two-dimensional reconnection models.     

Metric radio bursts and fine structures observed on 17 January, 2005

A complex radio event was observed on January 17, 2005 with the radio-spectrograph ARTEMIS-IV, operating at Thermopylae, Greece; it was associated with an X3.8 SXR flare and two fast Halo CMEs in close succession. We present dynamic spectra of this event; the high time resolution (1/100 s) of the data in the 450–270 MHz range, makes possible the detection and analysis of the fine structure which this major radio event exhibits. The fine structure was found to match, almost, the comprehensive Ondrejov Catalogue which it refers to the spectral range 0.8–2 GHz, yet seems to produce similar fine structure with the metric range.