COVERAGE PERFORMANCES ANALYSIS ON COMBINED-GEO-IGSO SATELLITE CONSTELLATION1

The Combined-GEO-IGSO constellation is the combination of Geostationary Earth Orbit (GEO) satellite and Inclining GeoSynchronons Orbit (IGSO) satellite.The Combined-GEO-IGSO constellation can integrate the advantages of GEO and IGSO to achieve regional coverage.In order to discuss the performances of the Combined-GEO-IGSO constellation,the performances of coverage,elevation,diversity,and transmission are simulated in China and surrounding regions by Satellite Tool Kit (STK).The simulation results show that:the combined constellation can reach higher multi-satellite coverage and higher communication elevation in China and surrounding areas; the Doppler shift,delay,and propagation loss of this constellation have little impact on the system.As regional coverage constellation,the Combined-GEO-IGSO is feasible.     

一种改进的自适应增强-支持向量回归机的故障预测方法

针对支持向量回归(SVR)方法对突变故障预测精度较低的问题,提出了一种改进的自适应增强算法(AdaBoost)提升SVR故障预测性能。该方法通过AdaBoost算法获取训练样本中突变点的权重并构造加权支持向量回归机增强突变点的训练,以提高对突变故障预测精度。利用自适应权重裁减方法剔除权重较小的样本点,来提高算法的训练速度。将本文方法用于发动机磨损元素的时间序列预测中,一步预测相对误差达到了0.025. 实验结果表明该方法在保证预测精度的前提下有效地提高了故障预测速度。     

Adaptive blind equalization for MIMO systems uadaptive blind equalization for MIMO systems under α-stable noise environmentnder α-stable noise environment

The presence of non-Gaussian impulsive noise in wireless system can degrade the performance of existing equalizers and signal detectors. In this paper, the problem of blind source separation and equalization for MIMO systems in heavy-tailed impulsive noise is studied. A generalized multiuser constant modulus cost function by employing the fractional lower-order statistic of the equalizer input signal is proposed. The associated adaptive blind equalization algorithm based on a stochastic gradient descent method is defined as fractional lower-order multi-user constant modulus algorithm (FLOS MU CMA). Computer simulations are presented to illustrate the performance of the new algorithm.     

基于闪存的大容量存储阵列

大容量、高速度、高密度、低功耗、低成本、高可靠性和灵活性一直是星上记录设备信息存储技术的主要研究内容和追求目标。文中研究并实现了一种基于NAND型Flash的高速大容量固态存储系统,成果为实际研制应用于星的基于闪存的大容量存储器奠定了基础,具体较好的指导和借鉴意义。     

Satellite broadcasting of time and frequency signals

The authors discuss the advantages of broadcasting time from a satellite over the more traditional ground based methods such as short wave and low frequency standard time and frequency broadcasts. The authors describe several one way satellite time services currently operational and discuss, in particular, a broadcast service using the Indian domestic satellite INSAT. The signal format, transmitting and receiving setups, and the methods for satellite position prediction are described in detail for the INSAT broadcast. Some typical results of time and frequency calibration are also discussed     

基于无线传感器网络的TDOA-CTLS定位算法研究

节点位置的确定是无线传感器网络的应用基础.为了提高传感器网络节点定位的精度,利用转移矩阵和观测矩阵噪声之间的关系,采用约束总体最小二乘算法求解时差定位问题.通过将定位问题转化为一个约束总体最小二乘问题,然后又将有约束问题等价为无约束的问题,利用Newton算法进行迭代求解.最后计算机仿真结果验证了该算法的有效性.     

基于三维激光扫描的倾斜圆面直径测量系统

针对倾斜圆面的空间几何特征,提出将三维激光扫描技术与虚拟环境 引导定位结合的快速圆面直径测量系统。该系 统通过圆面边缘端点来约束移动激光扫描仪的扫描视角与深度,并在虚拟环境下实时跟随扫 描仪轨迹构建虚拟测量基准面, 进而参考已标识的端点与基准面相对位移变化,来逐步规划扫描仪的轴向运动路径,以此实 现边缘轮廓的自动高质量采样; 依据高度特征变化识别定位圆面边缘端点,并结合空间投影和最小二乘原理拟合出圆面直径 。为验证系统的精度和可靠性, 对处于不同倾斜状态的圆台工件(55±5mm)进行直径检测。结果显 示,系统可在3s内完成直径测量,检测分辨率为5μm、 检测精度为20μm。实际运行结果表明,该设计系统具有高自动性和 高效性,能很好满足在线生产中对倾斜圆面直径的检测要求。     

Prestoring Lithium into Stable 3D Nickel Foam Host as Dendrite‐Free Lithium Metal Anode

Lithium metal is considered a “Holy Grail” of anode materials for high‐energy‐density batteries. However, both dendritic lithium deposition and infinity dimension change during long‐term cycling have extremely restricted its practical applications for energy storage devices. Here, a thermal infusion strategy for prestoring lithium into a stable nickel foam host is demonstrated and a composite anode is achieved. In comparison with the bare lithium, the composite anode exhibits stable voltage profiles (200 mV at 5.0 mA cm^?2) with a small hysteresis beyond 100 cycles in carbonate‐based electrolyte, as well as high rate capability, significantly reduced interfacial resistance, and small polarization in a full‐cell battery with Li₄Ti₅O₁₂ or LiFePO₄ as counter electrode. More importantly, in addition to the fact that lithium is successfully confined in the metallic nickel foam host, uniform lithium plating/stripping is achieved with a low dimension change (merely ≈3.1%) and effective inhibition of dendrite formation. The mechanism for uniform lithium stripping/plating behavior is explained based on a surface energy model.     

TDDI产品Mo-Al-Mo膜层腐蚀原因分析及改善

为降低TDDI产品Lead Open型线不良发生率,本文对Lead Open的发生机理进行了研究及改善验证。对TDDI产品生产数据进行了对比,对Mo-Al-Mo结构的SD膜层进行研究,根据以上结果确定改善方案并投入验证。首先,明确了Lead Open发生率与Delay Time的关系。接着,对SD膜层的微观结构进行了表征。然后,根据膜层结构和不同金属的电化学特征,建立了SD膜层电偶腐蚀模型。分析表明:Mo、Al两种金属间存在1.47V的电极电位差,具有很强的电偶腐蚀倾向性,且表层Mo中存在10nm级别的贯穿性孔洞,直径为0.4nm的水分子可轻易渗入,进而引发电偶腐蚀。表层Mo厚度增加25%后,其腐蚀速度较量产条件降低30%,Lead Open发生率降低1.4个百分点,维持在0.1%的较低水平,满足TDDI产品量产对该类不良发生率的要求。     

BIST/Digital-Compatible Testing of RF Devices Using Distortion Model Fitting

Testing of Radio Frequency (RF) circuits for nonlinearity specifications generally requires the use of multiple test measurements thereby contributing to increased test cost. Prior RF test methods have suffered from significant test calibration effort (training for supervised learners) when using compact tests or from increased test time due to direct specification measurement. On the other hand, due to aggressive technology scaling, there are plenty of digital transistors available that can be used to simplify testing of Analog/Mixed-Signal (AMS) and RF devices. In this paper, an RF test methodology is developed that: (a) allows RF devices to be tested for several distortion specifications using distortion model fitting algorithms in test time comparable to what can be achieved using supervised learning techniques while retaining the accuracy of direct specification measurement, (b) allows multiple RF specifications to be determined concurrently from a single data acquisition and (c) allows digital-compatible testing/BIST to be performed using digital testers or on-chip built in self-test (BIST) circuitry. With regard to (a), a key benefit is that no training of supervised learning algorithm is necessary. The proposed method based on distortion model fitting is shown to give excellent results across common RF performance metrics while providing ~10× improvements in test time compared to previous methods.