Predicting the sample mean by extreme order statistics

Summary This paper considers the prediction of the sample mean by extreme order statistics when the population distribution is known. The predictor and its mean square error are found. The problem is studied in details for the normal model.     

滚齿加工误差分析与检验组(之三)Ⅲ、齿轮的切向误差与检验项目

本文是“滚齿加工误差分析与检验组”一文的第三部分。这部分的主要内容是分析与研究滚齿加工时产生切向误差(亦称运动偏心)的原因,切向误差的特征,切向误差与检验项目的关系、数学模型等。     

Determinants of Residential Land-Use Conversion and Sprawl at the Rural-Urban Fringe

We estimate a probit model of residential land conversion using parcel-level data from a rural-urban county in Ohio. Spatial landscape pattern metrics are used to quantify land-use patterns and to link patterns of residential sprawl with factors estimated to influence parcel-level land conversion. Findings indicate that the location of new residential development is influenced by preferences for lower density areas that nonetheless are close to existing urban development. Combined, these forces have generated a moderated pattern of residential sprawl. Spatial error autocorrelation is controlled using a spatial sampling technique that enables consistent estimation of the probit model.     

大学生英语写作错误归因

写作一直是大学英语教学中的一个难点,也是学生学习英语时最头疼的问题。文章分析了大学英语写作中的典型错误,对其成因进行了初步探究,并提出了一些提高英语写作水平的几点建议。     

Globalization, Financial Volatility and Monetary Policy

Recently it has often been claimed that globalization eases the job of central banks as it helps to tame inflation. This is used to argue that central banks (particularly the ECB, referring to the objectives as laid down in the EU Treaty) could or should reduce their efforts in the fight against inflation in favor of supporting the general economic policies of the governments. This paper takes a critical look at this argument, pointing to the structural changes associated with globalization and to the corresponding increase in uncertainty by which the central banks are affected. As an example of this, the increase in financial volatility is analyzed and explained as the result of optimal portfolio allocation, and its implications for monetary policy are discussed.     

Price relationships between qualitatively differentiated agricultural products: organic and conventional wheat in Germany

Organic agriculture, which produces commodities that can be qualitatively differentiated from conventional food products, has grown into an important market in many countries. The dynamics of commodity prices in both sectors are partly interdependent, but are also shaped by independent determinants and have rarely been studied. We analyze organic food markets and their interdependencies with conventional markets in the context of wheat markets in Germany, which have been subject to a number of fundamental changes during the last two decades. Based on institutional market characteristics, we suggest a flexible Markov‐switching asymmetric time series model. We find a pronounced temporal sequence of market phases that differ in their asymmetric dynamics and the extent to which the organic price is influenced by the conventional price. Organic wheat prices tend to be increasingly connected to prices of conventional wheat.     

Do Vietnamese upland farmers benefit from high world market prices for maize?

For rural households in the north of Vietnam, maize cropping is the main source of income. In the face of the world market price increases of the recent past, we analyze the regional marketing chain of this commodity qualitatively and econometrically investigating to what extent smallholder farmers in developing countries are affected by international price movements. Vietnamese maize markets are found to be well integrated. Recent price hikes have fully transmitted along the regional supply chain so that farmers profited. Nevertheless, adverse factors such as increasing input prices have neutralized these benefits resulting in a decline in real income of smallholders.     

基于电缆网时域反射信号检测与预处理技术研究

运行电缆网时域反射信号检测与预处理技术研究。应用小波分析变换电缆网时域反射信号的奇异点进行检测与预处理误差较大,采用小波分析的反射波消噪技术提出一种小波分析最优分解层数的自适应确定函数算法。     

一种改进的民用GPS异步欺骗技术

针对民用全球定位系统(Global Positioning System,GPS)欺骗中存在的欺骗信号伪码相位同步问题,通过欺骗建模分析得到了主要误差来源于探测系统定位精度。基于传统单路滑动牵引入锁技术,理论分析了功率损失主要来源于载波偏差。针对工程应用中欺骗信号构造时初始码相位超前滞后的不确定带来的欺骗起效时间二值性,提出基于码片误差滞后扩展处理的改进技术,并利用多路并发滑动优化单路滑动时间过长问题。通过软件接收机、商用接收机实验验证了改进的滑动入锁技术在实际应用中具有欺骗起效时间短、欺骗更可靠的特点。该研究成果可为民用GPS欺骗技术研究人员提供参考。     

芯片物理指纹的可用性评估

芯片物理指纹(Physical Unclonable Function,PUF）技术可用于构建新型可信认证体系,具有小型化、低功耗、高安全特性。通过对芯片物理指纹认证性能的研究,提出了对芯片物理指纹可用性相关概念的量化表征。基于芯片物理指纹实测数据进行了更多样本数据的模拟,分析了芯片物理指纹认证参数设置与安全性要求的关系,实现了对芯片物理指纹的可用性的有效评估,为芯片物理指纹技术进一步实现工程化应用提供了参考。