无空洞真空共晶技术及应用

在采用功率芯片集成产品时,往往要求热阻小,可靠性高.在这方面,真空共晶技术与传统的芯片贴装方法如环氧粘结或者手动氮气保护共晶技术相比更具优势.分析了真空环境对共晶焊接的影响,同时对影响真空共晶焊接的工艺因素进行了剖析,通过这些因素的控制,可以得到无空洞的焊接.同时给出了真空共晶技术可能的应用.     

一种新型可扩展的多级多平面分组交换结构的图论模型与性能分析

该文提出了一种新型可扩展的多级多平面(MPMS)分组交换结构。首先建立了MPMS的图论模型,定量地描述了MPMS中相邻连通性和端口可达性,定义了MPMS的均衡顶点和竞争顶点,并证明了MPMS决定交换性能的输入端口与输出端口间的无阻塞条件。从性能参数和结构复杂度等方面与单级交叉开关做了对比分析,结果表明MPMS可以获得P倍的最大端口速率,平方倍的最大端口数,线性比例增长的结构复杂度,具有良好的可扩展性。     

VWDK调制真的可实现吗?

为验证VWDK调制方式高频谱利用率特性,该文先介绍了VWDK调制的基本概念,然后对其调制与解调的进行了仿真验证,仿真结果证明其“超窄带”并不是通常意义下的窄带传输。进而又从理论推导得到该种调制方式的功率谱,并对其功率谱的能量分布进行了分析,对其高效频谱利用率提出了质疑。     

多天线感知无线电中的协作频谱感知算法

不同于以往单天线感知用户的频谱感知研究,该文提出多天线情形下基于最优功率分配和协作分集的频谱感知算法。根据信道条件利用奇异值分解(SVD)在每根天线上进行功率注水,并考虑多天线情况下两用户网络协作频谱感知授权用户的判决检测过程,利用基于指数衰减的路径损耗模型,分析多天线感知网络的各态历经容量和检测授权用户的概率及时间。理论分析及仿真结果表明,多天线感知用户通过最优功率分配和协作频谱感知不仅使感知网络具有最大的各态历经容量,同时改善系统的检测性能。     

一种基于IoT控制的小区间功率控制方法

该文针对OFDMA蜂窝系统中上行干扰特性,提出了基于IoT控制的小区间功率控制方法。该方法通过相邻小区相互交换干扰信息,对传统的功率控制进行修正,并根据调整原则和调整步长,提出了4种控制方法,使得系统IoT更稳定,吞吐量更高。仿真证实了这4种控制方法都优于传统未加IoT控制的功率控制方法,其中基于固定比较对象的自适应调整步长的功率控制方法最优。     

PLL DEMODULATION TECHNIQUE FOR M-RAY POSITION PHASE SHIFT KEYING

The paper presents a kind of transmission system which employs M-ary Position Phase Shift Keying (MPPSK) to send data and Phase Locked Loop(PLL)based techniques for data retrieve.With a single PLL,MPPSK demodulation is achieved,as well as carrier recovery and symbol synchronization.Firstly,MPPSK modulation method is briefly introduced.2PPSK's PSD expression is given with its optimization result.Orthogonal Phase Detector (PD) and static threshold are used for the purpose of wider phase range and simplicity in demodulation.The data rate is alterable,which is 4.65 kbps for 2PPSK and 9.3 kbps for 4PPSK in the paper.Then some indicative comparisons in Signal to Noise Ratio Symbol Error Rate (SNR-SER) are made among 2PPSK,3PPSK and 4PPSK,of which 4PPSK has proved to be optimal in ten slots each symbol conditions.And finally,it is demonstrated by system simulations that lower than 10-4 Symbol Error Rate(SER)performance can be obtained at 13 dB symbol SNR.     

6mm波导腔耿氏管功率合成器

本文介绍6mm波导腔双源阵四管(耿氏管)功率合成器的原理、结构、优化计算、性能(例如:各种含义下的合成效率,推频曲线,频率漂移问题和功率稳定性)和实验方法。文中给出的理论和技术适用于厘米波和毫米波波导腔合成器。     

开关电容V/Q变换器及其在接地阻抗模拟中的应用

文中提出一个V/Q变换的广义跨导概念,并应用在开关电容阻抗模拟中。使用V/Q变换器,可以用电压传递函数实现所希望的阻抗函数。由此概念出发,分别导出了前差FD,后差BD和双线性S/Z变换的三种接地开关电容频变负阻SC-FDNR电路。如果所选用的电压传递函数电路对杂散电容不灵敏,那么实现的模拟阻抗电路对杂散电容也是不灵敏的。作为文中的一个例子,用FD-FDNR电路组成一个谐振回路,实验表明其频响特性与理论分析相一致。     

FPGA-based test bed for measurement of AM/AM and AM/PM distortion and modeling memory effects in RF PAs

Using a field-programmable gate array (FPGA) development board, a digital signal processor (DSP) builder, and the phase-to-amplitude conversion principle, a low-cost system for measuring the amplitude-to-amplitude (AM/AM) and amplitude-to-phase (AM/PM) distortion curves of radio frequency (RF) power amplifiers (PAs) is presented. The state of the art based on the measurements and preliminary studies of AM/AM and AM/PM distortion curves is discussed. A full digital control of the test bed simulated/emulated in Matlab/Simulink is introduced to recalculate the known AM/AM and AM/PM measurements stored as look-up table (LUT). Finally, the low-cost system comprises the memory polynomial model (MPM) that involves the nonlinearity order and memory effects of real PAs.     

基于顾客社会关系对转换成本前项的扩展研究（英文）

The effects of customers' social ties on switching costs have recently attracted researchers' attention.This study formally included customers' social ties as a new antecedent to supplement those elucidated by Burnham in 2003.Through empirical research,this study successfully verified the reliability and validity of items created to measure social ties,and it demonstrated the facilitating effects of social ties as an antecedent on customers' procedural and relational switching costs.Finally,the study lists managerial implications aimed at retaining customers through knowledge of this added antecedent.