In this paper, the authors obtain an Ambrosetti–Prodi type result of T-periodic solutions of the first-order differential equations u'(t)=a(t)u(t)-f(t,u(t))+s, t∈ R by topological degree method, where T>0 is a constant, a:ℝ→ [0,∞ ) are T-periodic functions with ∫ _0^Ta(t)dt=0 , s∈ℝ is a parameter; f is a Carathéodory function and T-periodic for the first variable, which f(t, u) satisfies locally coercive at infinity.

本文讨论了二阶离散周期边值问题{?2u(t?1)+f?u(t)+g(t,u(t))=s,t∈[1,T]Z,u(0)=u(T?1),?u(0)=?u(T?1)解的个数与参数s的关系,其中g:[1,T]Z×R→R是连续函数,f≥0是常数,T≥2是一个整数,s∈R.本文运用上下解方法及拓扑度理论获得了存在常数s0∈R,当s与s0位置关系变化时该问题没有解、至少有一个解、至少有两个解的结果.

用Guo-Krasnoselskii不动点定理给出半正二阶离散周期边值问题{Δ2 u(t-1)+a(t)u(t)=λf(t,u(t)),t∈[1,T]?,u(0)=u(T),Δu(0)=Δu(T)正解的存在性和多解性结果,其中λ>0为参数,[1,T]?={1,2,…,T},f:[1,T]?×[0,∞)→?连续且存在常数D>0,使得f(t,u)≥-D,(t,u)∈[1,T]? ×[0,∞),a:[1,T]?→(0,∞),0

文章通过分析新时代大学生理想信念教育出现的新问题,提出了新对策,即强化思想政治理论课程的主渠道作用;扩大理想信念教育工作阵地,营造理想信念教育的良好氛围;搭建形式多样、内容丰富的理想信念教育平台;着力加强高校理想信念教育师资队伍的建设.

Taking the number of isolated nodes, the maximum connectivity length, the global network efficiency and other parameters as quantitative indicators to evaluate connectivity, the Vehicular Ad-hoc Networks(VANETs)is established by VanetMobisim and the evolution of VANETs connectivity is studied under the Nakagami fading channel model and deter-ministic channel model in detail. As the results show, the temporal correlation of networks is weak when VANETs is fully connected. When the connectivity of VANETs is low, all the connectivity indexes present heavy-tailed phenomenon and the network connectivity has a strong temporal correlation. Finally, the influence on the connectivity of VANETs is analysed led by the nodes density, path loss index and fading factor etc.

“电磁感应”这部分内容综合性强，题目难度大且灵活性高，学生难以理解各知识点间的联系与区别，以致难以掌握解题的规律和技巧。思维导图因具有发散、递进的特点，在复习该部分内容知识点时能够起到高效的作用。

The public transport network vulnerability of Lanzhou is studied based on complex network theory. Firstly, the bus stations network are constructed according to the space L model and the static topological properties is analyzed. Then, the metrics about the vulnerability of urban public transport network is established on the basis of the random failure and selective attack of complex networks, and the corresponding performances are presented. The results show that the vulnerability of a selective attack is far stronger than that of random failure because of the special features of the valley terrain in Lanzhou. Finally, combined with the vulnerability of public transport network, the key station selection strategy is studied. It shows that the selection strategy based on the degree is more suitable for Lanzhou. These results provide a theoretical basis to support decision making on transportation planning and urban traffic network optimization for Lanzhou.

建设环保、生态社会的要求越来越迫切地在社会建设中体现出来。城市污水的排放,严重影响了建设环保、生态社会的进程。所以城市污水的处理已经成为迫切需要解决的问题。通过对当代城市规划实践的深入调查,结合环境学理论的最新研究成果,对相应问题的实证分析提出城市规划中所应采取的环境保护对策。