经济转轨期农村经营模式:路径、绩效与创新

目前,我国农村实行的是以家庭承包经营为基础的双层经营体制。这种体制的弊端在于土地难以流转、经营规模太小、市场联系面窄、抵抗风险能力弱、农业资本投资不足、土地使用效率低等。要进一步发展农村经济,就必须创新经营模式,下一步应该把突破口放在以产权清晰为基础的统一经营上,建立农村家庭、涉农企业、集体和政府利益协同的产业链,把重点放在农产品的加工和流通环节,以企业为龙头,建立大市场大流通,实现规模经济效应。     

一类多项式零点问题的证明

多项式零点问题的证明,已见于若干学报或教材．其方法可谓多种多样,但显复杂．本文先将Rolle定理加以推广,称之为“广义Rolle定理”,然后借助于该定理,证明一类著名的多项式零点值问题．     

二维变系数线性微分系统的求解定理

给出二维变系数线性微分系统在已知某解的情形下求通解的公式,并直接应用此公式,导出几类二维变系数线性微分系统的通解公式.对理论和实际应用都是有益的.     

关于“高斯定理”的疑问

本文旨在澄清有关电磁学中“高斯定理”的诸多疑问,并指出它与高等数学中的“高斯定理”的区别。     

Limit theorems for dependent Bernoulli variables with statistical inference

We consider a class of dependent Bernoulli variables where the conditional success probability is a linear combination of the last few trials and the original success probability. We obtain its limit theorems including the strong law of large numbers, weak invariance principle, and law of the iterated logarithm. We also derive some statistical inference results which make the model applicable. Simulation results are exhibited as well to show that with small sample size the convergence rate is satisfying and the proposed estimators behave well.     

Asymptotic behaviour of binned kernel density estimators for locally non-stationary random fields

We investigate the asymptotic behaviour of binned kernel density estimators for dependent and locally non-stationary random fields converging to stationary random fields. We focus on the study of the bias and the asymptotic normality of the estimators. A simulation experiment conducted shows that both the kernel density estimator and the binned kernel density estimator have the same behavior and both estimate accurately the true density when the number of fields increases. We apply our results to the 2002 incidence rates of tuberculosis in the departments of France.     

An algorithmic approach to construct D-optimal saturated designs for logistic model

In this paper, locally D-optimal saturated designs for a logistic model with one and two continuous input variables have been constructed by modifying the famous Fedorov exchange algorithm. A saturated design not only ensures the minimum number of runs in the design but also simplifies the row exchange computation. The basic idea is to exchange a design point with a point from the design space. The algorithm performs the best row exchange between design points and points form a candidate set representing the design space. Naturally, the resultant designs depend on the candidate set. For gain in precision, intuitively a candidate set with a larger number of points and the low discrepancy is desirable, but it increases the computational cost. Apart from the modification in row exchange computation, we propose implementing the algorithm in two stages. Initially, construct a design with a candidate set of affordable size and then later generate a new candidate set around the points of design searched in the former stage. In order to validate the optimality of constructed designs, we have used the general equivalence theorem. Algorithms for the construction of optimal designs have been implemented by developing suitable codes in R.     

基于HHM-RFRM的船舶航行风险评估方法研究

船舶航行风险是由各种风险因素交互作用产生。综合 HHM-RFRM 理论，构建船舶航行多维风险情景危险度测度模型，以风险因素耦合视角探讨船舶航行风险管理问题。在船舶航行多维风险情景危险度测度模型中结合贝叶斯定理，对船舶航行风险情景进行了定性与定量化过滤、评级。最后以大连港某从事商务活动的货船为例，验证了所提出方法的可行性。传统的风险评估方法只能评估单个风险因素对系统的影响，此评估方法克服了这一局限性，为船舶航行风险管理提供新的视角。     

吉伯德-萨特思韦特防策略不可能性定理的逻辑初探

自20世纪70年代吉伯德-萨特思韦特防策略不可能性定理确立后，引起了数学、经济学、计算机科学和哲学等诸多领域中学者的广泛关注。然而，在国内外文献中，对吉伯德-萨特思韦特防策略不可能性定理的逻辑研究还比较少。基于此，借助公理化的方法探讨吉伯德-萨特思韦特防策略不可能性定理，并形式化地给出定理的内容和证明，力图把精细的逻辑推理应用于复杂的过程分析中，使防策略投票这一过程形式化、清晰化，以期能指导人们进行合理、有效的决策活动。