20世纪20年代的乡土文学状况

20世纪20年代的乡土文学作为乡土文学流派的源头，对乡土文学的发展、流变具有重要的启悟意义。对此一时期的乡土文学研究，概念研究、思想主题研究以及艺术美学研究是研究的中心和重点，对后起的乡土文学创作和评论产生了决定性的影响。     

伟大建党精神引领时代新人培养的三个维度:精神要义、实现思路与意义表达

伟大建党精神体现了马克思主义的科学世界观和方法论,它所蕴含的真理力量、信仰伟力、实践精神、人民情怀等为时代新人培养提供了丰厚精神滋养;以伟大建党精神引领时代新人培养,就要发挥学校主阵地、社会大课堂、融媒体大氛围、党史学习新契机、红色基因好传统的协同作用,增强实践自觉;教育引导青年筑牢实现中华民族伟大复兴中国梦的价值理想和为人民幸福而永久奋斗的价值追求.     

Node-weighted Steiner tree approximation in unit disk graphs

Given a graph G=(V,E) with node weight w:V→R ⁺ and a subset S⊆V, find a minimum total weight tree interconnecting all nodes in S. This is the node-weighted Steiner tree problem which will be studied in this paper. In general, this problem is NP-hard and cannot be approximated by a polynomial time algorithm with performance ratio aln n for any 0<a<1 unless NP⊆DTIME(n ^O(log n)), where n is the number of nodes in s. In this paper, we are the first to show that even though for unit disk graphs, the problem is still NP-hard and it has a polynomial time constant approximation. We present a 2.5ρ-approximation where ρ is the best known performance ratio for polynomial time approximation of classical Steiner minimum tree problem in graphs. As a corollary, we obtain that there is a polynomial time (9.875+ε)-approximation algorithm for minimum weight connected dominating set in unit disk graphs, and also there is a polynomial time (4.875+ε)-approximation algorithm for minimum weight connected vertex cover in unit disk graphs.     

Minimum number of disjoint linear forests covering a planar graph

Graph coloring has interesting real-life applications in optimization, computer science and network design, such as file transferring in a computer network, computation of Hessians matrix and so on. In this paper, we consider one important coloring, linear arboricity, which is an improper edge coloring. Moreover, we study linear arboricity on planar graphs with maximum degree \(\varDelta \ge 7\) . We have proved that the linear arboricity of \(G\) is \(\lceil \frac{\varDelta }{2}\rceil \) , if for each vertex \(v\in V(G)\) , there are two integers \(i_v,j_v\in \{3,4,5,6,7,8\}\) such that any two cycles of length \(i_v\) and \(j_v\) , which contain \(v\) , are not adjacent. Clearly, if \(i_v=i, j_v=j\) for each vertex \(v\in V(G)\) , then we can easily get one corollary: for two fixed integers \(i,j\in \{3,4,5,6,7,8\}\) , if there is no adjacent cycles with length \(i\) and \(j\) in \(G\) , then the linear arboricity of \(G\) is \(\lceil \frac{\varDelta }{2}\rceil \) .     

An individual-based model of information diffusion combining friends’ influence

In many real-world scenarios, an individual accepts a new piece of information based on her intrinsic interest as well as friends’ influence. However, in most of the previous works, the factor of individual’s interest does not receive great attention from researchers. Here, we propose a new model which attaches importance to individual’s interest including friends’ influence. We formulate the problem of maximizing the acceptance of information (MAI) as: launch a seed set of acceptors to trigger a cascade such that the number of final acceptors under a time constraint T in a social network is maximized. We then prove that MAI is NP-hard, and for time \(T = 1,2\) , the objective function for information acceptance is sub-modular when the function for friends’ influence is sub-linear in the number of friends who have accepted the information (referred to as active friends). Therefore, an approximation ratio \((1-\frac{1}{e})\) for MAI problem is guaranteed by the greedy algorithm. Moreover, we also prove that when the function for friends’ influence is not sub-linear in the number of active friends, the objective function is not sub-modular.     

ATM无线网纠错编码研究

根据６０ＧＨｚ无线信过的特点提出对ｃｅｌｌ字头和信息字段分别采用ＢＣＨ短码和ＲＳ编码方法。另外，还提出了一种新的ｃｅｌｌ字头，包含新提出的ＢｌｏｃｋＮｕｍｂｅｒ字段，能对付深衰落造成的长突发错误，且与原ｃｅｌｌ字头兼容，理论计算表明，所提出的纠错编码方案能比较有效地将６０ＧＨｚ无线信道质量提高至ＡＴＭ技术适应的水平。指出了在６０ＧＨｚ无线信道条件下，采用ＡＴＭ技术实现无线通信网综合业务是可行的。     

Broadcast Routing with Minimum Wavelength Conversion in WDM Optical Networks

We consider dynamic routing of broadcast connections in WDM optical networks. Given the current network state, we want to find a minimum set of network nodes S such that a broadcast routing using only the nodes in S as wavelength conversion nodes can be found. This ensures that the average conversion delay from the source to all destinations is minimized. We refer to the problem as Broadcast Conversion Node Selection (BCNS) problem. We prove that BCNS has no polynomial-time approximation with performance ratio ln n for < 1 unless NPDTIME(n^{O(log log n)}) where n is the number of vertices in the input graph. We present a greedy approximation algorithm for BCNS that achieves approximation ratio 2+ln n. Simulation results show that the algorithm performs very well in practice, obtaining optimal solutions in most of the cases.     

农民“被市民化”问题及思考

随着城镇化的快速发展,大量农民转变为市民。然而,在农民市民化过程中,广大城郊地区却出现了“被市民化”现象,即一种农民非自主选择的制度性市民化现象。农民失去土地是“被市民化”的根本途径,而户籍制度改革、职业变更、劳动力流动等因素在农民“被市民化”过程中具有间接辅助作用。文章对农民“被市民化”过程中存在的“暴富”后的困境、精神边缘人等相关问题进行分析,并在此基础上对新市民的角色再造加以思考,以期为“被市民化”的相关研究及实践完善提供参考与启示。     

产能有限的供应商主导的双渠道分销策略研究

在供应商产能有限的背景下,研究供应商的最优分配策略和双渠道分销的问题。根据期望利润最大化建立供应商渠道分配模型,依据纳什均衡确定供应商的最优定价、最优产能和最优分销策略。结果表明,在双渠道策略的情况下,供应商应该优先满足销售企业的销售量。若供应链的销售量恰好得到满足,供应商应该按最优产能生产。供应商的渠道选择与供应商产能、供应链各节点的盈利能力和生产成本有关。