Estimating the fundamental frequency of a periodic function

In this paper we consider the problem of estimation of the fundamental frequency of a periodic function, which has several applications in Speech Signal Processing. The problem was originally proposed by Hannan (1974) and later on Quinn and Thomson (1991) provided an estimation procedure of the unknown parameters. It is observed that the estimation procedure of Quinn and Thomson (1991) is quite involved numerically. In this paper we propose to use two simple estimators and it is observed that their performance are quite satisfactory. Asymptotic properties of the proposed estimators are obtained. The large sample properties of the estimators are compared theoretically. We present some simulation results to compare their small sample performance. One speech data is analyzed using this particular model.     

A Comparison of Gambling by Minnesota Public School Students in 1992, 1995, and 1998

The purpose of this study was to compare rates of gambling among Minnesota public school students between 1992, 1995, and 1998. The three samples included 75,806 students in the 9th and 12th grades in 1992; 73,897 9th and 12th grade students in 1995; and 78,564 9th and 12th grade students in 1998. Students were administered the Minnesota Student Survey, a 121-item, anonymous, self-administered, paper-and-pencil questionnaire that inquires about multiple behavioral domains, including gambling behaviors. The same questionnaire, with minor revisions to the gambling items, was administered in 1992, 1995, and 1998 to students in their classrooms by the Minnesota Department of Education. The results showed two opposite trends. On the one hand, fewer students gambled in 1998 than in 1995 and 1992. On the other hand, there was a small, but growing number of 12th grade students who gambled frequently. In terms of trends over time for specific games, the lottery showed a significant decline in the number of 9th grade students who played at all. There was also a significant increase in the number of 12th grade students who played the lottery weekly or more often. The findings that frequent lottery gambling has increased among 12th grade students and that underage gambling continues among these students, are both cause for concern. This is the first generation of youth to be exposed to widespread accessability to legalized gambling venues and gambling advertising. Legalized gambling may be a new "rite of passage" for some of today's youth. It will be important to continue to monitor youth gambling and to provide information and resources to assist youth in making healthy decisions about their gambling behavior.     

Book Reviews

This article examines some difficulties associated with the Haynes–Stone model and attempts to clarify how the model can be justified as representing the hypothesis that “quantity is demand determined and price is supply determined.” It also argues that the applications of such a model as was done by Haynes and Stone might not have resolved the controversies related to the Phillips curve and the supply function of exports (or imports).     

常见英语错误缘说

我国常见英语错误的发生率之高和涉及面之广已成为建设和谐社会的一道煞风景.本文通过对实际错误病例的列举并逐一对导致错误的缘由进行解说,兼辅以据出权威出版物的更正,以正视听.     

论代理契约中决策方案的设计与选择

本文论述了以博奕关系简化复杂的代理关系,用必然等值评估代理人的优先选择曲线,根据代理人优先选择曲线的类型,分析代理人的风险态度,据以设计相应的激励方案的方法与过程.     

基于环境学习曲线的山东省SO2排放及节能减排潜力分析

基于1981—2006年的数据对山东省SO2排放的规律进行研究，得到山东省SO2排放的环境学习曲线。应用这一曲线，定量分析山东省17个地级市减少SO2排放的潜力，并结合2006年各市的万元GDP能耗情况，对它们的节能减排潜力进行综合评价。     

儿童拼图性识字的记忆研究

以艾宾浩斯的遗忘曲线为基本框架,通过拼图性学习和常规性学习两种不同学习生字方法的实验比较,对儿童识字的一般性规律进行研究。得到结论:拼图性识字在记忆的保持上优于常规性识字;拼图性识字在学习有笔画难度的字上优于常规性识字;拼图性识字同样符合艾宾浩斯的遗忘曲线规律。拼图性识字教学符合儿童以动作思维为主的认识特点,符合儿童心理的年龄特征,能提高对字形记忆的效果,让儿童可以有效、有趣、自主进行早期识字学习。     

载频解调式脉冲调制器的研制

介绍了一种新型载频解调式栅极脉冲调制器.调制器由2只脉冲变压器、载频调制控制电路、解调与脉冲输出电路组成.调制器采用了内载频脉冲驱动模式,利用了MOSFET的极分布电容对信号的延时作用,通过二极管解调还原调制管触发脉冲,最终输出正负电压的调制脉冲.载频信号频率大于200 kHz,隔离变压器具有尺寸小,绕组匝数少的特点.采用这种模式的调制器,输出脉冲宽度宽、前后沿小、工作比高.详细介绍了基于载频解调式脉冲调制器的应用实例,并对其性能参数进行了测试.     

Biased Bootstrap Methods for Reducing the Effects of Contamination

Contamination of a sampled distribution, for example by a heavy-tailed distribution, can degrade the performance of a statistical estimator. We suggest a general approach to alleviating this problem, using a version of the weighted bootstrap. The idea is to 'tilt' away from the contaminated distribution by a given (but arbitrary) amount, in a direction that minimizes a measure of the new distribution's dispersion. This theoretical proposal has a simple empirical version, which results in each data value being assigned a weight according to an assessment of its influence on dispersion. Importantly, distance can be measured directly in terms of the likely level of contamination, without reference to an empirical measure of scale. This makes the procedure particularly attractive for use in multivariate problems. It has several forms, depending on the definitions taken for dispersion and for distance between distributions. Examples of dispersion measures include variance and generalizations based on high order moments. Practicable measures of the distance between distributions may be based on power divergence, which includes Hellinger and Kullback–Leibler distances. The resulting location estimator has a smooth, redescending influence curve and appears to avoid computational difficulties that are typically associated with redescending estimators. Its breakdown point can be located at any desired value ε∈ (0, ½) simply by 'trimming' to a known distance (depending only on ε and the choice of distance measure) from the empirical distribution. The estimator has an affine equivariant multivariate form. Further, the general method is applicable to a range of statistical problems, including regression.     

按温度比例因子的低温双极晶体管优化设计

提出了一种按温度比例因子设计低温双极晶体管的设计规则。在考虑双极晶体管低温效应的前提下,着重分析了双极晶体管发射区和基区的浓度及宽度在低温下的变化情况。结合按温度比例子变化后任何特定温度下的双极晶体管电流增益和截止频率的优化结果,给出了这些参数在按温度比例因子规则设计时温度比例因子的变化参数。