协同通信系统中差分调制在Rayleigh衰落信道中的误码性能分析

根据源-中继-目的节点链路的等效信噪比模型,推导了检测传送和选择检测传送两种 协议下目的节点瞬时信噪比的概率密度函数和特征函数,基于此推导了协同DMPSK调制近似 误符号率的闭合表达式。推导结果不含积分表达式,方便计算,为系统设计和功率分配提供 了理论基础。最后通过仿真验证了推导结果的正确性。     

一种无人值守接力的靶场安控系统

本文论述了中国实行对外开放是邓小平和中国人民把握历史和时代发展规律作出的战略抉择并取得了巨大成就;分析总结了中国入世前对外开放的基本特征及其原因;重点探讨了中国入世后对外开放的新阶段、新特点及其应对措施,推动对外开放新阶段和开放型经济新发展。     

信道估计偏差对空时编码的OFDM系统性能的影响

本文研究了采用空时编码的OFDM系统的性能，通过Monte Carlo仿真分析了系统性能和信道估计偏差对系统的影响。     

海面低仰角数字微波通信系统性能及体制分析

本文介绍了海面低仰角数字微波通信系统的特点，对海面电波多径衰落进行了理论计算，指出了通信系统抗衰落的方法和手段，并给出了一种抗衰落通信系统在海面通信试验中的测试数据。     

LZW压缩数据的不均一两分段误码保护编码

由T.A.Welch提出的LZW数据压缩方法已经被广泛地应用于文字压缩。然而，因为误码对压缩数据的危害很大，所以对压缩数据的纠错编码是十分重要且必不可少的。本文分析了误码对LZW压缩数据的影响，指出同样的误码对用于重建辞书的前一部分压缩数据的危害比对后面的其它数据的危害要严重得多，提出用一种不均一两分段误码保护编码方法，对用于重建辞书的前一部分压缩数据进行更好地保护。计算机模拟显示，该方法比传统的误码保护方法更有效。     

快速Internet小波图像传输

对发展中国家的经济发展来说,当贸易因自由化而可能致使国家总体利益遭受损失时,对自由进行限制的修正自由规则是所取对应措施中最常见的做法,诸如补助金制度、投资限制政策、环境政策、竞争政策等.应该看到这些强有力的限制手段在束缚自由贸易而保护了自身利益的同时,却有悖于通过世界贸易的扩大可以增进宏观福利.在WTO这一多边贸易组织一时还难以协调发展中国家的国家利益与发达国家的自由贸易利益时,区域联合不失是对发展世界贸易的一种补充.     

ARBITRAGE BOUNDS FOR PRICES OF WEIGHTED VARIANCE SWAPS

We develop a theory of robust pricing and hedging of a weighted variance swap given market prices for a finite number of co‐maturing put options. We assume the put option prices do not admit arbitrage and deduce no‐arbitrage bounds on the weighted variance swap along with super‐ and sub‐replicating strategies that enforce them. We find that market quotes for variance swaps are surprisingly close to the model‐free lower bounds we determine. We solve the problem by transforming it into an analogous question for a European option with a convex payoff. The lower bound becomes a problem in semi‐infinite linear programming which we solve in detail. The upper bound is explicit. We work in a model‐independent and probability‐free setup. In particular, we use and extend Föllmer's pathwise stochastic calculus. Appropriate notions of arbitrage and admissibility are introduced. This allows us to establish the usual hedging relation between the variance swap and the “log contract” and similar connections for weighted variance swaps. Our results take the form of a FTAP: we show that the absence of (weak) arbitrage is equivalent to the existence of a classical model which reproduces the observed prices via risk‐neutral expectations of discounted payoffs.     

相位误差对OFDM无线图像传输系统的影响

正交频分复用（OFDM）技术应用于无线图像传输可解决由于图像数据量大带来的传 输效率问题,但系统子载波相位误差影响着OFDM图像传输质量。首先推导出一种相位误差存 在时MPSK信号误符号率近似式,然后,利用该近似式对带有相位误差的MPSK调制OFDM图像传 输系统的性能及图像接收质量进行了研究。结果表明,子载波相位误差会对OFDM系统性能产 生显著的影响,且当MPSK相位误差增大至π/M（M为MPSK调制电平数）时,增加信 噪比已无助于OFDM图像质量的改善。     

Does global liquidity drive commodity prices?

This paper tackles the question of whether a cross-sectional perspective on monetary policy is capable of explaining movements in global commodity prices. In this vein, we contribute to the rich literature on global liquidity in two different ways: on the one hand, to achieve a global series in terms of common monetary policy shocks, we propose a distinction between common and idiosyncratic factors across economies, as proposed by Bai and Ng (2004). Our second innovation stems from the consideration of a Markov-switching vector error correction model when analyzing time-varying short-run dynamics. Having identified the long-run structure which includes a proportional relationship between commodity prices and global liquidity in the first step, our results indeed show that the impact of a global liquidity measure on different commodity prices is significant and varies over time. One regime approximately accounts for times where commodity prices significantly adjust to disequilibria, while the second regime is characterized by either a weak or no commodity price adjustment. The fact that global liquidity also reacts to disequilibria in a specific regime demonstrates the two-way causality between monetary policy and commodity prices.     

机器人手指的抓取误差分析

本文对机器人不同类型的手指抓取误差进行了全面、细致的分析。既有定性的理论描述,又有定量的计算公式,还有具体的应用实例。因此可供机器人手指设计和使用人员参考。