基于FPGA 的1GHz高速采样处理平台设计

介绍了一种高速宽带采样的数字信号处理平台设计方法，论述了在XilinxV4 FPGA中如何实现高速同步时钟设计和高速数据同步接收设计，介绍了与该设计相关的一些高速模数混合电路设计方法和一种采样后数据捕获的方法。该设计方案已用于瞬时测频中，并取得了良好的效果。     

CDMA2000基站时钟同步系统及电路

CDMA2000基站以GPS／GLONASS标准秒信号作为整个系统的时钟同步基准，采用一种PLL（锁相环）＋DDS（直接数字频率合成器）＋PLL的结构实现。引入了时钟同步系统的总体方案。着重介绍了由AD9851和LMX2306构成的后级DDS＋PLL的电路设计和参数设置。根据实验结果对该方案的稳定性和适用性进行了分析。     

循环前缀在OFDM系统中的应用

本文详细论述了OFDM系统中循环前缀在削弱符号间干扰（ISI）、载波间干扰（ICI）以及在实现时频同步中的应用。在OFDM符号间插入循环前缀，可以减小ISI和ICI，并为实时时频偏移估计提供足够信息，使得系统同步结构简单且工作高效。     

开放式机载时间同步系统的架构设计

针对现有机载时间同步系统在综合航电系统架构下通用性和可扩展性不足的问题,提出了一种具有开放式特征的机载时间同步系统架构。首先根据机载时间同步系统应用需求,分析了机载平台可选的技术手段,然后围绕时间链路、时间处理、时间管理、时间应用等基本要素,将机载时间同步系统自上而下划分为三个部分,从而形成分层次的机载时间同步架构。该架构在层间采用了标准开放接口,能同时兼容多种机间时间比对链路,具备多时间管理和时间品质评估的能力。最后,介绍了该架构下的时间同步实现流程,并分析了影响同步精度的主要误差环节。桌面测试结果表明,所提架构能够实现优于10 ns的时间同步精度。     

降低头肩视频序列编码码率的一种新方法

由于会计上遵循权责发生制,财务操纵利润有很大的余地,因而关于会计造假的丑闻屡禁不止,这样,就使基于利润为基础的企业价值评估大打折扣。本文介绍了一种源于西方并已发展成熟的价值评估指标--自由现金流量,美国企业公布的年报都要求披露这一数据。相对于国内现通行的各项指标,它有很多突出优势,对进一步了解企业价值有一定的借鉴作用。最后,根据自由现金流量在实际运用中的局限性,提出几点建议。     

Trade intensity and business cycle synchronization: Are developing countries any different?

Trade intensity increases the business cycle co-movement among industrial countries. Using annual information for 147 countries for the period 1960-99 we find that the impact of trade intensity on business cycle correlation among developing countries is positive and significant, but substantially smaller than that among industrial countries. Our findings suggest that differences in the responsiveness of cycle synchronization to trade integration between industrial and developing countries are explained by differences in the patterns of specialization and bilateral trade.     

The World Is Not Enough! Small Open Economies and Regional Dependence

In this paper, we explicitly introduce regional factors into a global dynamic factor model. We combine new open economy factor models (emphasizing global shocks) with the recent findings of regional importance in the business cycle synchronization literature. The analysis is applied to a large panel of domestic data for four small open economies. We find that global and regional shocks explain roughly 30 and 20 percent, respectively, of the business cycle variation in all countries. While global shocks have most impact on trade variables, regional shocks explain a relatively large share of the variation in cost variables.     

HOW DO FISCAL CONSOLIDATION AND FISCAL STIMULI IMPACT ON THE SYNCHRONIZATION OF BUSINESS CYCLES?

Using quarterly data for a panel of advanced economies, we show that synchronized fiscal consolidation (stimulus) programmes in different countries make their business cycles more closely linked. We also find: (i) some evidence of decoupling when an inflation targeting regime is unilaterally adopted; (ii) an increase in business cycle synchronization when countries fix their exchange rates and become members of a monetary union; (iii) a positive effect of bilateral trade on the synchronization of business cycles. Global factors, such as a rise in global risk aversion and uncertainty and a reversal of nonstandard expansionary monetary policy, can also reduce the degree of co‐movement of business cycles across countries. From a policy perspective, our work shows that an inflation targeting regime coupled with simultaneous fiscal consolidations can lead to more business cycle synchronization.     

Hong Kong's growth synchronization with China and the US: A trend and cycle analysis

This paper investigates the synchronization of Hong Kong's economic growth with mainland China and the US. We identify trends of economic growth based on the permanent income hypothesis. Specifically, we first confirm whether real consumption in Hong Kong and mainland China satisfies the permanent income hypothesis, at least in a weak form. We then identify the permanent and transitory components of income of each economy using a simple state-space model. We use structural vector autoregression models to analyze how permanent and transitory shocks originating from mainland China and the US affect the Hong Kong economy, and how such influences evolve over time. Our main findings suggest that transitory shocks from the US remain a major driving force behind Hong Kong's business cycle fluctuations. On the other hand, permanent shocks from mainland China have a larger impact on Hong Kong's trend growth.     

A gossip based information fusion protocol for distributed frequent itemset mining

The computational complexity, huge memory space requirement, and time-consuming nature of frequent pattern mining process are the most important motivations for distribution and parallelization of this mining process. On the other hand, the emergence of distributed computational and operational environments, which causes the production and maintenance of data on different distributed data sources, makes the parallelization and distribution of the knowledge discovery process inevitable. In this paper, a gossip based distributed itemset mining (GDIM) algorithm is proposed to extract frequent itemsets, which are special types of frequent patterns, in a wireless sensor network environment. In this algorithm, local frequent itemsets of each sensor are extracted using a bit-wise horizontal approach (LHPM) from the nodes which are clustered using a leach-based protocol. Heads of clusters exploit a gossip based protocol in order to communicate each other to find the patterns which their global support is equal to or more than the specified support threshold. Experimental results show that the proposed algorithm outperforms the best existing gossip based algorithm in term of execution time.