Optimal designs for exponential regression

This paper is concerned with the optimal design problem for the particular case of non-linear parametrisation:the parameters to be estimated are included in exponents.Some properties of locally optimal designs as functions of estimated parameters are investigated and a table of such designs in given.We consider also designs to be optimal in the sense of minimax approach.     

On Calculations Involving the Maximum Cell Frequency

We describe a method of computing the cumulative distribution function of the maximum and minimum cell frequencies in sampling distributions commonly encountered in the analysis of categorical data.The procedure is efficient for exact or approximate calculation in both homogeneous and non-homogeneous cases, is non-recursive, and does not require Dirichlet integrals.Some related statistical problems are also discussed.     

参差重复频率分析和设计

雷达工作于脉冲工作状态时不可避免的会出现盲速现象。可通过参差重频的方法减少盲速带来的影响。在推导频率响应的基础上,该文采用最优化设计的方法进行参差周期的设计,详细考虑并推导得到了最优化搜索中几个重要参数,给出了其解析表达式。仿真结果和频率响应图表明,该方法得到的参差周期能将慢速扩大到原来盲速的数倍以上,有效地减少了盲速的影响。     

低频度事件保险产品选择谈判决策模型

本文考虑在低频度事件中保险产品选择问题,用效用理论及模糊数学知识建立了产品选择模型,并给出了算例,找到了使双方均满意的最优产品。     

Combining Food Frequency and Survey Data to Quantify Long-Term Dietary Exposure: A Methyl Mercury Case Study

Twenty-four-hour recall data from the Continuing Survey of Food Intake by Individuals (CSFII) are frequently used to estimate dietary exposure for risk assessment. Food frequency questionnaires are traditional instruments of epidemiological research; however, their application in dietary exposure and risk assessment has been limited. This article presents a probabilistic method of bridging the National Health and Nutrition Examination Survey (NHANES) food frequency and the CSFII data to estimate longitudinal (usual) intake, using a case study of seafood mercury exposures for two population subgroups (females 16 to 49 years and children 1 to 5 years). Two hundred forty-nine CSFII food codes were mapped into 28 NHANES fish/shellfish categories. FDA and state/local seafood mercury data were used. A uniform distribution with minimum and maximum blood-diet ratios of 0.66 to 1.07 was assumed. A probabilistic assessment was conducted to estimate distributions of individual 30-day average daily fish/shellfish intakes, methyl mercury exposure, and blood levels. The upper percentile estimates of fish and shellfish intakes based on the 30-day daily averages were lower than those based on two- and three-day daily averages. These results support previous findings that distributions of "usual" intakes based on a small number of consumption days provide overestimates in the upper percentiles. About 10% of the females (16 to 49 years) and children (1 to 5 years) may be exposed to mercury levels above the EPA's RfD. The predicted 75th and 90th percentile blood mercury levels for the females in the 16-to-49-year group were similar to those reported by NHANES. The predicted 90th percentile blood mercury levels for children in the 1-to-5-year subgroup was similar to NHANES and the 75th percentile estimates were slightly above the NHANES.     

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.     

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.     

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.     

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。