一类2n+1次多项式微分系统的局部极限环分支

研究了一类2n 1次多项式微分系统在原点的局部极限环分支问题,通过计算与理论推导得出了该系统原点的奇点量表达式,确定了系统原点的中心条件以及最高阶细焦点的条件,并在此基础上构造出系统在原点分支出4个极限环的实例.     

Uniqueness and value-sharing of differential polynomials of meromorphic functions

In this paper, we investigate uniqueness problems of meromorphic functions concerning differential polynomials sharing non-zero finite value and give some results. As particular cases of our results we deduce some significant results which improve several earlier results of Fang and Hong (2001) [2], Yang and Yi (2003) [7], Lin and Yi (2004) [5] and others.     

Value function,relaxation, and transversality conditions in infinite horizon optimal control

We investigate the value function $V:{\mathbb{R}}_{+}\times {\mathbb{R}}^n\to {\mathbb{R}}_{+}\cup \{+\infty \}$ of the infinite horizon problem in optimal control for a general—not necessarily discounted—running cost and provide sufficient conditions for its lower semicontinuity, continuity, and local Lipschitz regularity. Then we use the continuity of $V(t,?)$ to prove a relaxation theorem and to write the first order necessary optimality conditions in the form of a, possibly abnormal, maximum principle whose transversality condition uses limiting/horizontal supergradients of $V(0,?)$ at the initial point. When $V(0,?)$ is merely lower semicontinuous, then for a dense subset of initial conditions we obtain a normal maximum principle augmented by sensitivity relations involving the Fréchet subdifferentials of $V(t,?)$. Finally, when V is locally Lipschitz, we prove a normal maximum principle together with sensitivity relations involving generalized gradients of V for arbitrary initial conditions. Such relations simplify drastically the investigation of the limiting behavior at infinity of the adjoint state.     

常德市校园观赏植物资源调查

通过对常德市校园观赏植物种类分类和利用形式的调查,以及兰科植物在园林植物造景中的应用研究,结果表明,常德市校园观赏植物种类资源非常丰富,种类繁多,现有观赏植物256种,隶属94科,其中木本170种,草本78种,藤本8种.其观赏植物群落结构复杂多样,群落垂直结构有一层、两层、三层和多层,常见的为三层.     

温州调查：大学生对待社会主义核心价值体系——兼与河北等地的相关调查比较

对温州5所高校学生的调查以及与河北等地相关调查结果的对比分析发现：温州的大学生更多地认同和赞赏社会主义核心价值体系;他们认识更加多样、态度更加务实;赞成、认同与迷茫、冷漠的两极态势明显;男生、高年级同学对社会主义核心价值体系的认同度相对较低。认识和把握社会主义核心价值体系引领社会思潮的规律,进一步弘扬主旋律;关注男生中的消极情绪,引导他们健康成长;加强实践教育,让学生从实践中建立信念等,是强化理想信念教育的路径选择。     

Cauchy中值定理与Leibniz公式的推广

引入辅助函数的方法可将Cauchy中值定理推广到高阶形式,即两函数n阶Taylor展开误差的比值等于在某点两函数(n+1)阶导数比值的形式;用数学归纳法可将Leibniz公式中函数的个数推广至任意有限多个.     

河北省木本攀援植物及其在垂直绿化中的应用(综述)

对河北省木本攀援植物的区系组成、攀援习性和观赏特性及其在垂直绿化中的应用进行了综述。河北省共有木本攀援植物４５ 种，其中３６ 种为自然分布。分析表明，该类植物攀援习性完备、观赏价值高，可广泛应用于墙面、假山、枯树、棚架及篱垣等多种垂直绿化方式。     

浅议园林树木的养护与管理

概述了园林树木养护管理的意义,详细介绍了园林树木养护管理的各种措施。     

Managing contribution and capital market risk in a funded public defined benefit plan: Impact of CVaR cost constraints

Using a Monte Carlo framework, we analyze the risks and rewards of moving from an unfunded defined benefit pension system to a funded plan for German civil servants, allowing for alternative strategic contribution and investment patterns. In the process we integrate a Conditional Value at Risk (CVaR) restriction on overall plan costs into the pension manager’s objective of controlling contribution rate volatility. After estimating the contribution rate that would fully fund future benefit promises for current and prospective employees, we identify the optimal contribution and investment strategy that minimizes contribution rate volatility while restricting worst-case plan costs. Finally, we analyze the time path of expected and worst-case contribution rates to assess the chances of reduced contribution rates for current and future generations. Our results show that moving toward a funded public pension system can be beneficial for both civil servants and taxpayers.