On the admissibility of the maximum-likelihood estimator of the binomial variance

This paper addresses the admissibility of the maximum-likelihood estimator (MLE) of the variance of a binomial distribution with parameters n and p under squared-error loss. We show that the MLE is admissible for n ≤ 5 and inadmissible for n≥ 6.     

光学天线光中比对外差效率的影响

本文采用光障比的概念,计算和分析了使用卡塞格仑中天线系统时,激光相干检测的外差效率。结果表明,均匀本振场时,在探测器半径R_o近似等于0.75倍信号场爱里斑半径R_A时,外差效率达到最大。使用天线比不使用天线对信号光场的到达角要求更严,其值差一个数量级。     

A COMPARATIVE PERSPECTIVE ON RACIAL RESIDENTIAL SEGREGATION:

This article takes a first step to compare the residential segregation of blacks and Asians from whites in American and Canadian cities. The analysis is based on census data from 404 American and 41 Canadian cities. African Americans in the United States experience a higher level of residential segregation than Asians in U.S. cities. On the other hand, blacks in Canada experience the same low level of segregation as Asians. To explain the different experiences of blacks in the United States and Canada, a multivariate model is proposed and tested. The results reveal several patterns. First, African Americans are consistently obstructed much more than Asian Americans by their proportion in the city. In contrast blacks in Canada are not. Second, the residential segregation patterns of African Americans are affected strongly by the labor market and strucutral changes of the economy in the city. However, the structural change of the economy in the city has a very weak effect on the level of residential segregation of Asian Americans, black Canadians, and Asian Canadians.     

A Systemic Approach to Racial Residential Patterns

This paper applied the model of Linear System of Action developed by Coleman (1992) to understand racial composition in neighborhoods from a systemic approach. The model had an advantage to consider how an individual household simultaneously maximizes all desirable neighborhood qualities with limited socioeconomic resources. The model generated relative values of socioeconomic resources and neighborhood qualities of each racial group in the exchange process. In addition, the model estimated a preference hierarchy of neighborhood qualities of each group. Results suggested that blacks and Asians in Canada tend to live in neighborhoods with higher proportions of their own groups because blacks may be steered away from predominantly white neighborhoods and Asians experience low returns on their socioeconomic resources in improving spatial contact with whites.     

Cellular Bucket Brigades on U‐Lines with Discrete Work Stations

It is challenging to maximize and maintain productivity of a U‐line with discrete stations under the impact of variability. This is because maximizing productivity requires assigning workers to suitable tasks and maintaining productivity requires sufficient flexibility in task assignment to absorb the impact of variability. To achieve this goal, we propose an operating protocol to coordinate workers on the U‐line. Under the protocol the system can be configured such that its productivity is maximized. Workers are allowed to dynamically share work so that the system can effectively absorb the impact of variability. Analysis based on a deterministic model shows that the system always converges to a fixed point or a period‐2 orbit. We identify a sufficient condition for the system to converge to the fixed point. Increasing the number of stations improves productivity only under certain circumstances. The improvement is most significant when the number of stations in each stage increases from one to two, but further dividing the U‐line into more stations has diminishing return. Simulations based on random work velocities suggest that our approach significantly outperforms an optimized, static work allocation policy if variability in velocity is large.