数字中频接收机中的数字AGC的设计与实现

介绍了数字自动增益控制(AGC)技术在数字中频接收机中的实现方法’,提出了利用 DSP Builder模型库设计的一种实用的数字自动增益控制电路,所设计的电路在数字中频接收机系统内工作良好。该数字 AGC具有快速收敛、结构简单、性能稳定和成本低等特点。占用 Altera StratixⅡ FPGA 片上163个自适应逻辑单元(ALUTs)。     

New inequalities for finite and infinite group problems from approximate lifting

In this paper, we derive new families of facet‐defining inequalities for the finite group problem and extreme inequalities for the infinite group problem using approximate lifting. The new valid inequalities for the finite group problem include two‐ and three‐slope facet‐defining inequalities as well as the first family of four‐slope facet‐defining inequalities. The new valid inequalities for the infinite group problem include families of two‐ and three‐slope extreme inequalities. These new inequalities not only illustrate the diversity of strong inequalities for the finite and infinite group problems, but also provide a large variety of new cutting planes for solving integer and mixed‐integer programming problems. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Optimum step‐stress accelerated life test plans for log‐location‐scale distributions

This article presents new tools and methods for finding optimum step‐stress accelerated life test plans. First, we present an approach to calculate the large‐sample approximate variance of the maximum likelihood estimator of a quantile of the failure time distribution at use conditions from a step‐stress accelerated life test. The approach allows for multistep stress changes and censoring for general log‐location‐scale distributions based on a cumulative exposure model. As an application of this approach, the optimum variance is studied as a function of shape parameter for both Weibull and lognormal distributions. Graphical comparisons among test plans using step‐up, step‐down, and constant‐stress patterns are also presented. The results show that depending on the values of the model parameters and quantile of interest, each of the three test plans can be preferable in terms of optimum variance. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Homeland Security and Intelligence: Can Oil Mix with Water in an Open Society?

The newest US Cabinet department is Homeland Security (DHS). One of the most controversial aspects in the process of developing this entity is the role of intelligence in providing information on the increasing terrorist threat. This article examines the intelligence challenges for homeland security. In doing so, it explores the problems of merging disparate cultures - law enforcement vs intelligence, civil entities vs military, federal vs state and local jurisdictions, and domestic focus vs international perspective. Given the nature of the globalized, asymmetric threat, the need for more and better intelligence sharing is obvious. Terrorists and other criminals do not respect international boundaries; in fact, they exploit them in an effort to prevent effective and timely countermeasures. This demands that robust multinational collaboration and interagency coordination be practiced.     

'Brotherhoods' and 'Associates': Chechen Networks of Crime and Resistance

The traditional forms of Chechen society - the extended family, the clan, the religious brotherhood - have proven to be effective building blocks on which to construct network-based structures both for modern organized crime and also for fighting a guerrilla war against the Russians in Chechnya. These networks have evolved in the face of external pressure and are proving durable and successful, even as they are supplemented by separate networks of Islamic extremists, devoted both to guerrilla warfare and also a campaign of terrorism within Russia.