企业如何有效开展研发与标准化同步工作

随着企业对标准化工作的不断重视，研发与标准化同步正成为企业标准化工作的重点。文章在总结实践经验的基础上，从开展研发与标准化同步的意义，开展该项工作的资源保障，主要开展的内容以及开展效果的评价等方面进行了阐述，为企业有效开展研发与标准化同步工作提供了有益的借鉴。     

A comparative analysis of stock market cycles

In this article, we date the ‘recession’ and ‘expansion’ phases of 46 stock markets around the world from December 1994 to September 2013. We use the Harding and Pagan methodology to identify peaks and troughs in these stock market indices. This approach enables us to establish periods of synchronization between the markets based on the timing of peaks and troughs and to measure this synchronization by means of the Harding and Pagan statistic. We find that several recent world crisis episodes and simultaneous recoveries can be identified with this method. We also present evidence demonstrating an increase in the pro-cyclicality of stock markets around the world.     

符号定时偏差对OFDM系统性能的影响

针对符号定时偏差对OFDM系统的影响进行了分析,推导了AWGN信道下定时偏差与信噪比损失的近似关系式,并通过仿真对分析结果进行了验证.研究表明,由于采用循环前缀,符号定时适度超前不会对系统性能造成大的影响,而定时滞后则会引入符号间干扰,使系统性能恶化.因此符号定时不一定要很精确,但一定要特别准确.     

OFDM系统采样钟补偿算法及其FPGA实现

利用数字内插滤波器完成全数字域采样钟同步已广泛应用于OFDM数字接收机中.文中利用两个Farrow结构的内插滤波器,同时提高工作时钟对过采样信号进行数字域内插,完成接收端和发送端之间的采样时钟的完全匹配,并且根据硬件器件的特性和算法结构,逐级进行模块变量定点处理.基于实测数据的分析表明,该FPGA数字域采样钟补偿算法不仅有稳定的性能,而且其模块化设计也有利于更高阶算法或多通道系统的实现.     

突发模式下PSK信号的载波估计和位同步技术

介绍了一种适合于突发模式下PSK信号的快速载波估计和位时钟恢复的算法,该算法基于特定图案的前导字,在前导字阶段采用匹配滤波相关的前向技术直接获取载波频差估计值和位同步时钟的相位信息,利用数字相关得到载波初相的估计值.此算法结构简单,可估计的载波频差范围约为符号率的±10%,且计算量不大,适合数字硬件实现.实测结果验证了该方法的可行性和有效性.     

一种采用可变同步帧的OFDM符号定时同步算法

符号定时同步是正交频分复用（Orthogonal Frequency Division Multiplexing,OFDM）系统中最为关键的同步之一。针对现有的基于数据辅助类的同步算法中帧头存在持续时间长、抗噪声性能差和对载波频偏敏感等问题，提出了一种可变长度的同步帧结构，采用滑动差分相关算法完成符号定时同步。仿真结果表明，提出的同步帧结构持续时间短于一个OFDM符号周期，并且训练序列长度可以通过估算信噪比大小而灵活控制。同时，所提算法在归一化载波频偏为12（远远超过晶振的误差范围 ±10-5）的情况下正常工作；在高斯白噪声和多径衰落信道中都有较好的性能，且其流水线结构易于硬件实现。     

适用于多速率高阶QAM的定时同步改进算法

针对速率可变的高阶正交幅度调制(QAM)信号定时同步问题，提出了一种基于Gardn er理论的定时同步改进算法。新算法改原有滤波器结构为两级插值级联优化结构来实现多速 率信号的定时同步，可独立于载波同步单独使用，比传统结构具有更强的普遍适用性。仿真 结果表明，该算法可以准确地对速率可变的128QAM信号进行同步。     

Nonuniform Staggered Prices and Output Persistence

Staggered prices are a fundamental building block of New Keynesian dynamic stochastic general equilibrium models. In the standard model, prices are uniformly staggered, but recent empirical evidence suggests that deviations from uniform staggering are common. This paper analyzes how synchronization of price changes affects the response to monetary policy shocks. I find that even large deviations from uniform staggering have small effects on the response of output. Aggregate dynamics in a model of uniform staggering may serve well as an approximation to a more complicated model with some degree of synchronization in price setting.     

LDPC码的改进迭代比特翻转译码算法

为提高低密度奇偶校验（LDPC）码的低复杂度硬判决译码算法的性能，提出了一种改 进的比特翻转（BF）译码算法，在迭代时利用一个交替的门限模式对多个比特进行翻转，降 低了每次迭代时比特被错误翻转的概率，从而有效提高了译码性能。仿真结果表明，与BF算 法相比，该算法在保持低复杂度的基础上获得了更好的译码性能和更快的收敛速度。     

Synchronization of Innovation and Vehicle Projects: Proposal of a Management Tool at Renault SAS

The success of a vehicle on the market depends on its price, reliability, and attractiveness; for the latter, innovations are the key elements in the differentiation from competitors. Managing the processes of selecting and integrating innovation projects into vehicle projects is therefore crucial. This article presents a management tool that aims at managing the interplay between innovation projects and vehicle projects. The objectives are to increase and optimize the amount and value of innovation projects integrated into vehicle projects. The tool, called “Profilor,” is based on the concept of intrusiveness, which is presented from a theoretical and empirical point of view.