IEEE1588v2高精度时钟同步协议的总体设计与实现

随着网络技术的发展,音频传输逐渐网络化,为保证音频数据传输的实时性,对异步的以太网提出了高精度的时间同步要求。而IEEE1588标准定义的PTP(Precision Time Protocol)协议正是为实现高精度时钟同步而制定的。本文系统地介绍了IEEE1588v2(第二版本的PTP协议)的原理,并从软件实现的角度给出了IEEE1588v2的总体设计。     

一个半导体PN结从未提及的问题的探讨

PN结是半导体技术的关键所在,它又称为内电场,具有一定的电位差,但为什么做成二极管后在它的两端却没有电压呢?这个问题在所有的模电书籍上都未提及。本文针对这个问题进行分析探讨。     

Is East Asia an optimum currency area?

This paper assesses the empirical desirability of the East Asian economies to an alternative exchange rate arrangement (a monetary union) that can potentially enhance the exchange rate stability and credibility in the region. Specifically, the symmetry in macroeconomic disturbances of the East Asian economies is examined as satisfying one of the preconditions for forming an Optimum Currency Area (OCA). We extend the existing literature by improving the methodology of assessing the symmetry shocks in evaluating the suitability of a common currency area in the East Asian economies employing the Bayesian State-Space Based approach. We consider a model of an economy in which the output is influenced by global, regional and country-specific shocks. The importance of a common regional shock would provide a case for a regional common currency. This model allows us to examine regional and country-specific cycles simultaneously with the world business cycle. The importance of the shocks decomposition is that studying a subset of countries can lead one to believe that observed co-movement is particular to that subset of countries when it in fact is common to a much larger group of countries. In addition, the understanding of the sources of international economic fluctuations is important for making policy decisions. The falling share of country specific factor and the rising role of region factor indicate that East Asia has become increasingly favorable for a monetary union. However, the share of country-specific factor that is still significant implies that it could be costly to renounce individual currencies to advance into a monetary union in East Asia.     

蔬菜中苯硫磷残留量检测的不确定度评定

依据JJF 1059.1-2012方法,对气相色谱法测定蔬菜中苯硫磷农药残留量的不确定度进行分析评定。测定过程中产生的不确定度主要来源于标准物质称量和样品测量重复性。分析结果表明：蔬菜中苯硫磷残留量为0.012 m g/kg时,其扩展不确定度为0.0034 m g/kg（k=2）。     

一种抗远近效应的扩频码同步方法

给出了一种直扩通信系统的码同步方法.该方法的基本思想是首先完成扩频码的检测,然后比较将检测向量与期望用户扩频向量的相关值,得到接收信号中期望用户扩频码的相位,继而完成同步.这种方法的运算量较小,且不需要采用训练序列.文中给出了存在强多址干扰时,在高斯信道和瑞利衰落信道下的数值仿真结果.     

网络时间同步系统的设计与实现

互联网上进行时间同步具有重要的意义。本文首先介绍了NTP协议的原理,然后分析了提高授时精度的各种算法,最后设计并实现了网络时间同步系统。该系统的服务器部分是由ARM实现,客户端软件是通过socket编程实现。该系统中通过使用NTP算法和计算机内部高精度定时器,授时精度获得了进一步的提高。     

CHEN系统的混沌同步

分析了CHEN系统的稳定性，用APD方法构造了一个同步系统，并用FORTRAN程序进行了数值仿真，给出了系统同步误差图，结果表明驱动系统和响应系统能够很好的达到同步。     

自适应帧同步器的设计与实现

“9·11”事件后美国发起了全球范围内的金融反恐战,本文介绍了金融反恐的由来、国际上关于金融反恐的标准、世界上主要国家目前的反洗钱反恐融资(AML/CFT)机制以及我国金融反恐的现状,并分析了金融反恐目前存在的问题和困难。     

USA,Japan and the Euro Area: Comparing Business‐Cycle Features

There has been much discussion of the differences in macroeconomic performance and prospects between the USA, Japan and the Euro area. Using Markov‐switching techniques, we identify and compare specifically their major business‐cycle features and examine the case for a common business cycle, asymmetries in the national cycles and, using a number of algorithms, date business‐cycle turning points. Despite a high degree of trade and financial linkages, the cyclical features of USA, Japan and the Euro area appear quite distinct. Documenting and comparing such international business‐cycle features can, for example, aid the development of business‐cycle models and inform policy making.