An Algorithm to Detect the Presence of 3D Target Motion from ISAR Data

We present an algorithm to detect the presence of 3D target motion from ISAR data. Based on the 3D point scatterer model, we first examine the effect of 3D motion on ISAR imaging. It is shown that existing motion compensation algorithms cannot properly focus targets exhibiting 3D motion during the imaging interval. An algorithm is then derived to blindly detect the degree of 3D target motion from raw radar data. It is based on measuring the linearity of phases between two or more point scatterers on the target. The phase estimation is implemented using the adaptive joint time-frequency technique. Examples are provided to demonstrate the effectiveness of the 3D motion detection algorithm with both simulation and real ISAR data. The detection results are corroborated with the truth motion data from on-board motion sensors and correlated with the resulting ISAR images.     

以3G为核心的通信新技术综述

随着第三代移动通信标准的发展,涌现出各种新兴的通信技术,它们所带来的变化是巨大的,影响是深远的。这些技术进步是革命性的,它大大提高并拓展了人与人、人与机器甚至机器与机器之间的通信能力,并进一步挖掘了通信潜力。该文主要系统分析了3G中采用的通信新技术,并对这些新技术的应用前景进行了展望。     

无线MIMO系统的容量分析及其在3G中的应用

在无线MIMO(MultipleInputMultipleOutput)系统信号模型的基础上,分析了无线MIMO系统的容量,讨论了无线MIMO系统提高频谱利用率的基本原理,并且给出收发天线数量和信噪比对系统容量影响的试验结果。最后,对无线MIMO系统的应用,尤其在第三代移动通信中的应用做出了比较详细的说明。     

有向图的先深遍历与显示

图论是一门应用性很强的学科 ,在计算机科学、信息论等各个方面都有着广泛的应用。对图的概念和遍历方法进行了简单的阐述。并以有向图为例 ,介绍了有向图的先深遍历和简单显示 ,以及如何用C程序语言对其进行的实际编程。     

真空荧光显示屏基板绝缘层的质量控制

详细地分析了影响真空荧光显示屏基板断极和连极的主要原因是绝缘层的印刷质量，并提出了强制绝缘层印刷质量的措施。     

Synthesis and characterization of EuBa2Ca2Cu3O9−x: The influence of temperature on dielectric properties and charge transport mechanism

High dielectric constant materials have a crucial importance for various microelectronic applications such as memory devices, supercapacitors etc. Among other insulators, perovskite structured oxide materials attract great interest not only for their high dielectric constants but also their unique electrical and magnetic properties such as superconductivity etc. From this point of view, a new Europium based copper oxide layered material with perovskite structure (EuBa₂Ca₂Cu₃O_9−x coded as Eu-1223) has been synthesized by solid state reaction method in this work. The physical and chemical properties of Eu-1223 have been determined by FTIR, SEM, XRF, XRD, TGA and DTA techniques. The influence of temperature on impedance and dielectric properties of Eu-1223 has been investigated by impedance spectroscopy measurements performed within the frequency interval of 5 Hz–13 MHz between 298 K and 408 K temperatures. It has been found that the Eu-1223 material has high dielectric constants at each temperature operated. In addition, Eu-1223 sample behaves as a colossal dielectric material up to 300 kHz for 408 K due to observation of dielectric constant values which are greater than 10³. Furthermore, it has been revealed that Eu-1223 material can be used as thermally sensitive resistors in electronic circuits due to its decreasing resistance with increasing temperature. Moreover, it has been observed that the relaxation frequency of the system shifts from 46.5 kHz (low frequency radio wave band) to 1.57 MHz (mid frequency radio wave band) as the temperature increasing from 298 K to 408 K. According to dc conductivity investigations, the variation of dc conductivity with the inverse of temperature satisfies linear relationship that indicates a thermally activated nearest neighbor hopping conduction. On the other hand, it has been determined that ac conductivity has frequency dependent relation which obeys ω^s for the high frequency region. Furthermore, the frequency exponent, s, which takes values between 0.7 and 0.4, shows a decreasing behavior with increasing temperature. In conclusion, ac charge transport mechanism has been predicted as correlated barrier hoping for Eu-1223.     

Joint relay selection and resource allocation in cooperative device-to-device communications

Device-to-device (D2D) communications allow proximate cellular user equipments (UEs) to communicate with each other directly under the control of base station (BS). In this paper, considering the selection relaying (SR) rule which allows a subset of potential relays to forward the source’s data to the corresponding destination, we first establish a multi-relay system model where a D2D UE can act as not only a source but also a potential relay for another D2D link, and then analyze the cooperation behaviors among selfish UEs. Next a simple strategy is proposed to deal with the relay selection problem, and then the fair and efficient resource sharing problem among cooperating D2D UEs is formulated as a bargaining game. Since the game function is non-convex, we turn to an iterative method by introducing an auxiliary function to get the proportional fair resource allocation results. The system efficiency and fairness are proved by numeral simulation results.     

全彩LED显示屏的节能化设计

全彩色LED大屏幕是一个高能耗的产品。针对LED显示屏的节能问题,对LED显示屏供电系统、供电电源以及控制方法进行了研究及优化,提出了＂LLC谐振＋同步整流的集中-分布式＂电源方案和针对不同LED二极管的＂分类供电＂模式。同时将采用上述方案设计的LED屏供电系统与一般的供电系统进行了对比和计算,得出的结论是：采用本文提出的新型电源方案相对于传统方法,可以节能约20%;若采用文中提出的新型LED供电模式,还将进一步节约15%的能量。因此该显示屏的节能化设计具有重要的社会效益和经济效益。     

基于全景虚拟现实技术的科普系统

本文设计了基于全景虚拟现实技术的科普系统架构及功能框架.主要针对现实中的科普植物对象进3D建模,并进行三维全景展示,实现一个基于Web3D的科普系统.     

音频码流分析工具设计与实现

介绍了一种支持多标准（MPEG-1,AC-3和AVS）音频码流分析的软件实现方案。基于标准的参考解码器,采用面向对象的编程思想,设计了一种灵活配置的实现结构,不仅能解析出标准中定义的码流信息。根据用户的需求返回解码过程的中间结果,附加波形显示及音频播放等功能,而且方便对其他音频格式进行扩展。首先讨论了码流分析的意义及相关音频标准,然后简介了码流分析工具的架构及具体实现,最后进行了总结和展望。