机载雷达主瓣地杂波频率跟踪系统的内场模拟测试

分析了一种具有开闭环结合和零中频处理的主瓣地杂波频率跟踪系统的工作原理,详细阐述了对其跟踪性能进行内场模拟测试的原理及方法,最后给出了部分测试结果。     

A股市场中市盈率应用的若干问题——关于市盈率问题的若干研究(下)

"A股市场中市盈率应用的若干问题"是上期论文"关于市盈率问题的若干研究"的下篇,它以本轮熊市为背景,借助于数量化方法,研究与探讨了在A股市场及其投资的几个重要方面(如价值评估、投资分析、决策及回报等)中,使用市盈率指标的一些问题。     

从性别平等视角看“关爱女孩”行动

"关爱女孩"行动实施以来,其政策效果究竟如何,课题组经过调查之后认为,尽管"关爱女孩"行动起了一定的遏制作用,但它并未触动问题的根本,人们的生育观念并没有真正改变,男孩偏好依然严重.应基于性别平等的观点,从制度上着手改变男女不平等的根源,进而引导人们真正做到"生男生女顺其自然".     

Estimating the Technology of Cognitive and Noncognitive Skill Formation

This paper formulates and estimates multistage production functions for children's cognitive and noncognitive skills. Skills are determined by parental environments and investments at different stages of childhood. We estimate the elasticity of substitution between investments in one period and stocks of skills in that period to assess the benefits of early investment in children compared to later remediation. We establish nonparametric identification of a general class of production technologies based on nonlinear factor models with endogenous inputs. A by‐product of our approach is a framework for evaluating childhood and schooling interventions that does not rely on arbitrarily scaled test scores as outputs and recognizes the differential effects of the same bundle of skills in different tasks. Using the estimated technology, we determine optimal targeting of interventions to children with different parental and personal birth endowments. Substitutability decreases in later stages of the life cycle in the production of cognitive skills. It is roughly constant across stages of the life cycle in the production of noncognitive skills. This finding has important implications for the design of policies that target the disadvantaged. For most configurations of disadvantage it is optimal to invest relatively more in the early stages of childhood than in later stages.     

Pricing and momentum of syndicated credit in Europe

We investigate the determinants of syndicated loan prices for European borrowers, spanning the entire period of credit expansion and crisis. We construct a large data base consisting of 2102 rated syndicated loan deals from 1990 to 2008 in twenty three countries and ten economic sectors. We investigate the effects on the spread paid over the risk free rate of three major groups of factors: loan characteristics, borrower characteristics and characteristics of country of the borrower, using both qualitative and quantitative variables in a hedonic regression. The results show that all three groups are significant joint determinants of prices of syndicated credit. Our results confirm the existing literature but also provide for first time results stemming form the risk characteristics of the borrower and the country of the borrower. It is shown that distance-to-default as well as aggregate risk associated with country of the borrower are of great concern to the lenders and hence significantly affect the pricing of syndicated loans. Furthermore, we report that financial institutions and public utilities are able to negotiate for cheaper loans, but this result is reversed when financing is for acquisition purposes. Overall, risk, liquidity, solvency and sustainable performance by both the borrower and its domicile country are key determinants of syndicated loan prices.     

Development of a Dose‐Response Model for SARS Coronavirus

In order to develop a dose‐response model for SARS coronavirus (SARS‐CoV), the pooled data sets for infection of transgenic mice susceptible to SARS‐CoV and infection of mice with murine hepatitis virus strain 1, which may be a clinically relevant model of SARS, were fit to beta‐Poisson and exponential models with the maximum likelihood method. The exponential model (k= 4.1 × l0²) could describe the dose‐response relationship of the pooled data sets. The beta‐Poisson model did not provide a statistically significant improvement in fit. With the exponential model, the infectivity of SARS‐CoV was calculated and compared with those of other coronaviruses. The does of SARS‐CoV corresponding to 10% and 50% responses (illness) were estimated at 43 and 280 PFU, respectively. Its estimated infectivity was comparable to that of HCoV‐229E, known as an agent of human common cold, and also similar to those of some animal coronaviruses belonging to the same genetic group. Moreover, the exponential model was applied to the analysis of the epidemiological data of SARS outbreak that occurred at an apartment complex in Hong Kong in 2003. The estimated dose of SARS‐CoV for apartment residents during the outbreak, which was back‐calculated from the reported number of cases, ranged from 16 to 160 PFU/person, depending on the floor. The exponential model developed here is the sole dose‐response model for SARS‐CoV at the present and would enable us to understand the possibility for reemergence of SARS.     

Sequential Estimation of Dynamic Discrete Games: A Comment

Recursive procedures which are based on iterating on the best response mapping have difficulties converging to all equilibria in multi‐player games. We illustrate these difficulties by revisiting the asymptotic properties of the iterative nested pseudo maximum likelihood method for estimating dynamic games introduced by Aguirregabiria and Mira (2007). An example shows that the iterative method may not be consistent.     

Analysis of the Market‐Based Adjustable Outsourcing Contract under Uncertainties

The market‐based adjustable contract for customized goods or services has emerged in outsourcing practices. Its objective is to minimize the operational risks inherent in today's volatile environment of operations. Our research reveals several important properties of this contract through a continuous‐time analytical approach. Specifically, we consider the determination of this contract between two risk‐averse firms through a Nash bargaining process. We derive the optimal adjusting mechanism analytically and extensively analyze the application boundary of the market‐based adjustable outsourcing contract. We conclude by discussing implications for practice and research.     

Gamma failure‐time mixture models: yet another way to establish efficacy

Using a Yamaguchi‐type generalized gamma failure‐time mixture model, we analyse the data from a study of autologous and allogeneic bone marrow transplantation in the treatment of high‐risk refractory acute lymphoblastic leukaemia, focusing on the time to recurrence of disease. We develop maximum likelihood techniques for the joint estimation of the surviving fractions and the survivor functions. This includes an approximation to the derivative of the survivor function with respect to the shape parameter. We obtain the maximum likelihood estimates of the model parameters. We also compute the variance‐covariance matrix of the parameter estimators. The extended family of generalized gamma failure‐time mixture models is flexible enough to include many commonly used failure‐time distributions as special cases. Yet these models are not used in practice because of computational difficulties. We claim that we have overcome this problem. The proposed approximation to the derivative of the survivor function with respect to the shape parameter can be used in any statistical package. We also address the issue of lack of identifiability. We point out that there can be a substantial advantage to using the gamma failure‐time mixture models over nonparametric methods. Copyright © 2003 John Wiley & Sons, Ltd.     

中华女子学院学生身体素质现状分析

通过对中华女子学院两个年级118名学生立定跳远、仰卧起坐、800米三项身体素质的测试,三项体育测试平均得分75.08分。其中,学生最弱的项目是立定跳远,800米成绩则出现两极分化的现象。三项体育测试两个年级平均成绩无差异。针对以上结果分析其原因,提出进一步提高学生身体素质的建议和方法,且为体育教学改革提供理论依据。