基于k最近邻回归的频谱占用度预测

认知无线电技术可以在授权用户和非授权用户间进行频谱分配,预测模型的建立可帮助非授权用户推断频谱空洞是否可用,不仅能提升频谱利用率而且还能降低冲突率。采用理论分析、监测实验、数学建模、数据实证等方法,对频谱占用度建模理论进行了研究。针对频谱的可预测性问题,通过对数据集的分析,使用k最近邻(kNN)回归模型预测频谱的信道-场强值。基于观测数据呈现出的周期性,提出了一种针对周期性数据进行优化的kNN模型,并用其进行预测。比较了原始kNN回归模型和优化后的周期性kNN模型在测试数据上的预测精度,结果表明优化后的模型比原始的kNN模型有着更好的预测精度。     

基于数据结构的递归程序实现策略探讨

递归是一种重要的程序设计方法,但在教学过程中一直是个难点.本文从方法论的角度对递归程序设计进行系统的阐述.介绍了递归程序设计的一般步骤和方法,以及如何通过分治和回溯等策略进行递归程序设计.     

递归神经网络自适应均衡抗突发干扰研究

短波信道的突发干扰对判决反馈递归神经网络自适应均衡器有破坏作用并能导致均衡器失效,从而影响整个通信系统的连续性。本文对突发干扰时判决反馈递归神经网络自适应均衡器特性进行了分析,提出了2种改进算法。仿真结果证明了这2种改进算法的有效性。     

基于相空间重构技术的国际原油价格时序特征

由于国际原油市场的复杂性,结构性预测方法很难实现准确的国际原油价格预测。因此,通过原油价格的时间序列,分析原油市场随时间变化的历史行为和规律,建立时间序列预测模型成为原油价格预测的又一重要研究方向。在建立原油价格时间序列预测模型之前,必须掌握原油价格时间序列的特征,才能选择合适的原油价格时间序列预测方法。     

基于非参量累积和的合作频谱感知

针对认知无线电网络中频谱感知的检测时延降低问题，提出了基于非参量累积和的合作频谱感知算法。本地认知用户预处理频谱观测数据，获得观测数据相对于信念值的正向漂移和负向漂移。为了缩短检测延迟，认知用户只将数据的正向漂移同步传输至融合中心。融合中心融合正向漂移得到判决信息，采用非参量累积和算法依时间序列顺序累加判决信息，判断主用户是否正在使用授权频段。为了解决不传输负向漂移引起的虚警问题，改进算法提出融合中心可以保留首次判决，经过等待时间间隔后再作出最终判决。相对于传统的软融合算法，改进融合规则的合作频谱感知算法具有较低的检测延迟。     

基于JSP递归算法的亲属称谓语推导及实现

亲属称谓语不仅是人类日常生活中所必需的交际方式，也是人类社会的文化选择，对其进行研究有着重要的意义。本文对家庭关系的结构进行了分析，推导了亲属称谓语之间的关系，利用JSP和数据库访问技术，实现了基于WEB的亲属称谓语的相互推导和递归查询。     

基于时钟和地址的跳频序列的产生和性能分析

在一般跳频系统中，跳频序列是由递归算法产生的，如PN序列以及混沌序列、模糊序列等。本文介绍的基于时钟和地址的跳频序列提供了一种新的产生方法。这种序列是由长比特设备地址和不断变化的长比特时钟信息经过一系列运算而产生的，即基于时钟和地址和跳频序列，该序列具有理想的均匀频谱特性和很长的周期；序列线性跨距很长，不容易被智能干扰机干扰；序列的汉明相关特性也很好；这个特点在多址接入通信中非常有用。该序列另一个重要特征是硬件实现简单容易，事实上，这种序列巳成功应用于蓝牙跳频系统中。本文主要介绍这种跳频序列的设计产生过程，并对序列的各种性能进行分析。     

基于多重交叉残差方法的空间目标旋转特性分析

针对传统的频谱分析和自相关函数反演周期时常出现虚假周期的问题，提出了多重交叉残差法处理空间旋转目标雷达散射截面(Radar Cross Section，RCS)的时间序列。以空间跟踪和监视系统(Space Tracking and Surveillance System,STSS)卫星为例，仿真了空间目标失稳旋转状态，对比了频谱分析、自相关函数和多重交叉残差3种方法的处理结果，发现当目标存在进动运动时多重交叉残差法抗干扰能力更强。在此基础上，进一步研究了不同章动角时多重交叉残差法对旋转周期的反演效果，结果表明章动角大小会影响旋转周期的反演准确度，且章动角达到一定数值后，卫星进动幅度过大导致RCS序列周期性模糊，无法用多重交叉残差法反演出旋转周期。     

基于混沌映射的差分跳频频率编

针对差分跳频系统频率编码及跳频序列的设计问题,提出利用混沌映射构造差分频 率编码,并分析了其频率状态转移的Markov性和编译码特点。最后检验了基于混沌映射的差 分跳频频率编码的统计性能,结果表明,其产生的跳频序列具有较好的均匀性和随机性,不 失为一种具有较高线性复杂度的有效的差分跳频转移函数。     

人民币汇率变动对我国进出口及贸易差额的传递效应——基于动态递归的分析

本文通过2000—2015年6月的数据分析人民币汇率变动对进出口和贸易差额的影响,实证结果显示人民币升值将导致我国进出口额和贸易差额的下降,为了分析人民币汇率变动对我国进出口及贸易差额的动态传递效应,采用递归回归对人民币汇率传递的动态变化进行分析,发现汇率变动对进出口的传递效应在汇改后2年内影响比较大,之后慢慢趋于稳定;汇率变动对贸易差额的传递效应在2011年之后逐渐显著。     

The decline in the British bank population since 1810 obeys a law of negative compound interest

Two models by Garnett et al. [J. Bus. Hist. 57(1):182-202 (2015)] for the organisational demography of British banks are explored analytically: the exponential model; and the agent-based system (ABM) governed by probabilistic interactions. Exact expressions for ABM expectation values are derived, revealing first that bank creations obey a ‘birth’ process, and second, that one of the ABM hypotheses may be discarded. The expectation values are used to demonstrate that beneath its stochastic implementation, the ABM model is a discrete analogue of the exponential model, meaning that the decline in the British bank population obeys a law of negative compound interest.     

学习型社会中人文主义价值理念回归与数字图书馆发展的再思考

分析了学习型社会的特征，通过介绍图书馆与社会发展的关系，讨论了图书馆对学习型社会具有的支持作用，提出人文主义价值理念的回归和数字图书馆的大力建设是学习型社会中图书馆发展的趋势。     

An Exploration of Frequent Service Failures in the Brazilian Airline Industry

This study explores how customer evaluations of service failures and failure recurrence impact negative emotions and intent to complain. A survey of 589 Brazilian airline passengers demonstrates the meditational effect of negative emotions such that customers who perceive failures as severe and/or preventable by the airline develop more negative emotions, which subsequently increases intent to complain. We also demonstrate the moderating role of failure recurrence such that failure recurrence reduces the effect of failure severity on negative emotions. Our findings have important implications for managers and airlines in order to mitigate negative outcomes following a service failure.     

Brown＇s Blossom in Britain-China

The overall strategic relationship between U.K. and China is ＂better than ever＂, China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit.     

Sinosteel：Extraordinary Moves in Industry Chess

Among the Fortune 500 firms,more and more images from China emerge out.On the 2008 list,Sinosteel Corporation,a landmark group of China industries quietly squeezes into the candidate line.As the largest steel service ＆ trade enterprise,its sales reached at RMB 111.24 billion,with a year-on-year increase of 83.03 percent,and the profit grew by 180.03 percent.On the Sinosteel 2008 Work Meeting,the president Huang Tianwen uttered,＂In the coming year,we will work for US$20 billion sales,and look forward to getting a position in Fortune 500 firms for ourselves.＂     

Walk Through Unusual Five Years—— An Exhibitor＇s Canton Fair Course

When the 103rd Canton Fair is approaching, an old friend of Canton Fair, Li Ying from Jiangsu prov-ince recollected his past five years＇ experiences to the grand trade meeting. Each year is special, with some unforgettable memories colored by the year.     

Jean-Pierre Duprieu： Willing to Be A Legate of Sino-French Business

Estaing, former French president, Valery Giscard d＇Estaing attended Sino-French Economic Seminar held in Shanghai in early April and said that the world center has shifted from the west to the east with many European and US companies entering into Asia, and China has the ability to play an important role in the world stage. Estaing, naming himself＂French Confucian＂, then said in Chinese that a cook-group includes 10 people in ancient Chinese soldier system and the cook is in charge of cooking for them. And people who belong to the same cook are actually ＂Partners＂.     

China''''s Stock Market Wave

The annual meeting of the World Economy Forum was held in Davos,a little town in Switzerland,on January 23rd to the 27th this year,with the theme"the Power fo Collaborative Innovation",over 2500 celebrates from ture political and cconomic circles of more than 80 countries and challengred logether to talk about the future of the global economy in 2008,A Forum for the problems and challenges that face whole world,some of the keywords which drew attention during the event were:the U.S.subprime mortgage crisis,soaring energy prices,the economic slowdown in the U.S.ermerging economic bodies,authority funds and the general unpredictable nature of the global economy.