PWPM信号的功率谱研究

对脉冲宽度、位置联合调制(pulse width and position modulation)简称 PWPM 方式的随机信号序列功率谱进行了研究,文献[1]的理论结果显示 PWPM 随机信号序列功率谱中存在符号(symbol)同步信号离散谱成分,这有利于在接收端正确接收 PWPM 信号.用计算机模拟估计了 PWPM 随机信号序列的功率谱.其结果也表明了 symbol 同步信号的存在.     

LFMCW雷达信号多周期模糊函数分析

给出了LFMCW雷达信号的多周期模糊函数,并与单周期信号进行了比较。讨论了在单周期和多周期的模糊函数联系,沿主轴切割模糊函数的性质和体积有限方面上两者特征的差别。仿真结果表明,增大周期可提高多普勒分辩力,但不能改善时延分辩力。     

On linear regression designs which maximize information

Necessary and sufficient conditions are established when a continuous design contains maximal information for a prescribed s-dimensional parameter in a classical linear model. The development is based on a thorough study of a particular dual problem and its interplay with the optimal design problem, extending partial results and earlier approaches based on differential calculus, game theory, and other programming methods. The results apply in particular to a class of information functionals which covers c-, D-, A-, L-optimality, they include a complete account of the non-differentiable criterion of E-optimality, and provide a constructive treatment of those situations in which the information matrix is singular. Corollaries pertain to the case of s out of k parameters, simultaneous optimality with respect to several criteria, multiplicity of optimal designs, bounds on their weights, and optimality which is induced by admissibility.     

Mean-Minimum Exact Confidence Intervals

This article introduces mean-minimum (MM) exact confidence intervals for a binomial probability. These intervals guarantee that both the mean and the minimum frequentist coverage never drop below specified values. For example, an MM 95[93]% interval has mean coverage at least 95% and minimum coverage at least 93%. In the conventional sense, such an interval can be viewed as an exact 93% interval that has mean coverage at least 95% or it can be viewed as an approximate 95% interval that has minimum coverage at least 93%. Graphical and numerical summaries of coverage and expected length suggest that the Blaker-based MM exact interval is an attractive alternative to, even an improvement over, commonly recommended approximate and exact intervals, including the Agresti–Coull approximate interval, the Clopper–Pearson (CP) exact interval, and the more recently recommended CP-, Blaker-, and Sterne-based mean-coverage-adjusted approximate intervals.     

On the ridge regression estimator with sub-space restriction

In the linear regression model with elliptical errors, a shrinkage ridge estimator is proposed. In this regard, the restricted ridge regression estimator under sub-space restriction is improved by incorporating a general function which satisfies Taylor’s series expansion. Approximate quadratic risk function of the proposed shrinkage ridge estimator is evaluated in the elliptical regression model. A Monte Carlo simulation study and analysis based on a real data example are considered for performance analysis. It is evident from the numerical results that the shrinkage ridge estimator performs better than both unrestricted and restricted estimators in the multivariate t-regression model, for some specific cases.     

Setting Priorities in Behavioral Interventions: An Application to Reducing Phishing Risk

Phishing risk is a growing area of concern for corporations, governments, and individuals. Given the evidence that users vary widely in their vulnerability to phishing attacks, we demonstrate an approach for assessing the benefits and costs of interventions that target the most vulnerable users. Our approach uses Monte Carlo simulation to (1) identify which users were most vulnerable, in signal detection theory terms; (2) assess the proportion of system‐level risk attributable to the most vulnerable users; (3) estimate the monetary benefit and cost of behavioral interventions targeting different vulnerability levels; and (4) evaluate the sensitivity of these results to whether the attacks involve random or spear phishing. Using parameter estimates from previous research, we find that the most vulnerable users were less cautious and less able to distinguish between phishing and legitimate emails (positive response bias and low sensitivity, in signal detection theory terms). They also accounted for a large share of phishing risk for both random and spear phishing attacks. Under these conditions, our analysis estimates much greater net benefit for behavioral interventions that target these vulnerable users. Within the range of the model's assumptions, there was generally net benefit even for the least vulnerable users. However, the differences in the return on investment for interventions with users with different degrees of vulnerability indicate the importance of measuring that performance, and letting it guide interventions. This study suggests that interventions to reduce response bias, rather than to increase sensitivity, have greater net benefit.     

就业市场文凭贬值的经济学分析

本文运用经济学有关原理对现在就业市场上的文凭贬值现象作了简要分析,指出文凭贬值现象的背后是就业市场的信号在一定程度上的失灵,对失灵的原因作了分析,并提出一些改善就业市场状况的建议。     

我国上市公司股利政策：现实选择与理论诠释

作为公司财务理论的核心内容之一,股利政策是公司在利润再投资与回报投资者两者之间的一种权衡。我国上市公司的股利政策具有不分配现象仍然普遍、股利形式规律性不强、股利政策缺乏稳定性和连续性等特征,导致最有说服力的信号理论和代理理论也难以解释我国上市公司的股利政策。针对这一问题,建议拓宽融资渠道,缩小不同融资方式的成本差异;完善法律法规,规范股利分配的信息披露制度;降低代理成本,保持持续稳定的现金股利政策;改善治理结构,建立健全小股东利益保护机制。     

《刑事诉讼法学》课程多元化、实践性教学模式探讨

《刑事诉讼法学》课程的教学应适应21世纪对法学本科教育目标的要求,即将学生培养成为“法律知识、技术、观念和信仰的有机统一的法律人”之目标努力。因此,改变传统的单一式教学模式势在必行。我们认为应采用多元化教学内容,多元化教学方式,注重实践性教学环节的教学模式施教,方可实现上述目标。