高功率微波武器对卫星的威胁及防范措施

基于高功率微波(HPM)对电子系统的毁伤效应,重点分析了HPM的两种耦合方式,对前门耦合卫星天线、光学窗口的场强分布和后门孔缝耦合进行初步仿真计算,并对相应的防护措施作了论述.最后提出解决卫星设备抗HPM的思路和研究方向.     

稳定苯乙烯/丙烯酸丁酯细乳液的制备

以十二烷基硫酸钠（SDS）作乳化剂,不同链长的脂肪烃或脂肪醇作共乳化剂,分别用搅拌和超声乳化方法制备一系列苯乙烯（St)／丙烯酸丁酯（BA）细乳液,测定细乳液稳定性的结构表明,SDS／十六烷（HDE）的乳化效果最佳,HDE先与单体混合结构超声波制备的细乳液最稳定,乳化剂,共乳化剂的种类和沈度,乳化温度,超声时间等对细乳液的稳定性均有影响。     

逆向工程中一种新的特征识别算法

从某种角度上说,逆向工程是从已有实物的测量数据点中提取其实体特征再进行模型重建的过程。本文提出了一种新的特征识别算法,其首先采用基于面积和法矢准则的数据分割技术,对测量数据点进行数据分割。然后从特征所包含的分割面(简称特征分割面)中提取能够惟一标识该特征的4种特征编码,分别为:表述特征截面形状的截面编码、描述特征凹凸性的凹凸编码、显示特征二维俯视轮廓形状的轮廓编码以及反映特征二维俯视轮廓是否封闭的开闭编码。最后将这4种编码输入到基于人工神经(BP)网络的自动特征识别系统中,识别出特征类型并提取特征参数,从而实现特征重建。着重研究并实现了从特征分割面中提取特征编码的算法,并验证了算法的有效性。     

Comparison of RO tropopause height based on different tropopause determination methods

The tropopause is an important boundary in the Earth’s atmosphere, and has been the subject of close attention from atmosphere and climate researchers. To monitor the global tropopause using radio occultation (RO) data, there are two primary methods, one is the widely used temperature lapse rate method, and the other is the bending angle covariance transform method which is unique to RO data. We use FengYun3-C (FY3C) and Meteorological Operational Satellite Program (MetOp) RO data and European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis data to determine differences in RO tropopause height calculated by these two methods. We compute biases of the RO lapse rate tropopause height (LRTH) and the RO bending angle tropopause height (BATH) relative to the ECMWF LRTH. The dependences of the tropopause height biases on tropopause height (TPH) retrieval method, latitude, season and RO mission are investigated. The results indicate that BATH show a consistent 0.8–1.2 km positive bias over the tropics and high latitude regions compared with LRTH, however, over 25° to 40° latitude in both hemisphere, BATH results are less stable. Furthermore, the mean bias between BATH and LRTH displayed a different symmetrical characteristic from 2017.12 to 2018.2 (DJF) compared to 2018.6–2018.8 (JJA). However, except for some bias over Antarctica, the mean value of both LRTH and BATH show a similar tropopause variation, indicating the consistency of both methods.     

Characterisation of residual ionospheric errors in bending angles using GNSS RO end-to-end simulations

Global Navigation Satellite System (GNSS) radio occultation (RO) is an innovative meteorological remote sensing technique for measuring atmospheric parameters such as refractivity, temperature, water vapour and pressure for the improvement of numerical weather prediction (NWP) and global climate monitoring (GCM). GNSS RO has many unique characteristics including global coverage, long-term stability of observations, as well as high accuracy and high vertical resolution of the derived atmospheric profiles. One of the main error sources in GNSS RO observations that significantly affect the accuracy of the derived atmospheric parameters in the stratosphere is the ionospheric error. In order to mitigate the effect of this error, the linear ionospheric correction approach for dual-frequency GNSS RO observations is commonly used. However, the residual ionospheric errors (RIEs) can be still significant, especially when large ionospheric disturbances occur and prevail such as during the periods of active space weather. In this study, the RIEs were investigated under different local time, propagation direction and solar activity conditions and their effects on RO bending angles are characterised using end-to-end simulations. A three-step simulation study was designed to investigate the characteristics of the RIEs through comparing the bending angles with and without the effects of the RIEs. This research forms an important step forward in improving the accuracy of the atmospheric profiles derived from the GNSS RO technique.     

航空发动机陆用改型设计与分析

本文针对航空发动机开展陆用改型研究,首先分析了由简单到复杂的几种技术方案,然后对某型涡扇发动机进行总体热力学计算分析,在此基础上采用内外涵混合气流后直接加装动力涡轮的方案进行准三维气动设计,动力涡轮的全三维流场校核效果良好,达到了方案设计要求.此外还对其它几种典型的航空发动机进行了陆改方案设计.计算结果表明:退役发动机...     

A novel BIST scheme for circuit aging measurement of aerospace chips

The avionics working environment is bad, easy to accelerate aging of circuits. Circuit aging is one of the important factors that influence the reliability of avionics, so circuit aging testing is of great significance to improve the reliability of avionics. As continuing aging would degrade circuit performance, aging can be monitored through precise measurement of performance degradation. However, previous methods for predicting circuit performance have limited prediction accuracy. In this paper, we propose a novel Built-In Self-Test (BIST) scheme for circuit aging measurement, which constructs self-oscillation loops employing parts of critical paths and activates oscillations by specific test patterns. An aging signature counter is then used to capture the oscillation frequency and in turn measure the aging state of the circuit. We propose to implement this measurement process by BIST. Experimental results show that the proposed in-field aging measurement is robust with respect to process variations and can achieve a precision of about 90%. The application of this scheme has a certain value to improve the reliability of avionics systems.     

应用UBET优化开式模锻中连皮厚度参数

连皮厚度是开式模锻工艺参数中的一个重要参量，它对模锻变形力和材料的消耗有很大的影响。本文应用上限单元法（ＵＢＥＴ）对连皮厚度进行了优化设计。基于连皮厚度和飞边高度间的相对大小关系，建立了三种不同的变形流动模式和动可容速度场，根据上限原理和黄金分割法，利用ＴｕｒｂｏＣ语言编程求解，获得了最大锻造力的最佳上限解，并和实验相比较，两者吻合得较好，表明建立的动可容速度场是合理可行的。以最大锻造力和连皮体积的乘积作为优化准则，更好地得到了最佳连皮厚度值。     

自调节模拟低通滤波器的研究

通过对有源低通滤波器，频率／电压转换器AD650及其变容二极管的特性分析，提出由信号频率来自调节有源低通滤波器截止频率的新设计方案，并对其可行性进行了分析和研究。