农民工返乡回流对当地新农村建设影响的冲量过程模型

2008年下半年以来,受世界金融危机和长三角、珠三角等沿海发达地区产业升级影响,农民工返乡回流,对当地新农村建设造成较大影响.构建冲量模型对这种影响进行实验模拟表明:农民工失业返乡将首先影响新农村生产发展、生活宽裕和乡风文明,随之村容整洁和民主管理也受拖累;发展农村非农产业,多渠道促进农民增收,并加强农村社会管理,可转危为机,将这种不利影响降到最低程度,使农民工失业返乡成为加快当地新农村建设的机遇和财富.     

An algorithm for detecting community structure of social networks based on prior knowledge and modularity

An algorithm is proposed to detect community structure in social network. The algorithm begins with a community division based on prior knowledge of the degrees of the nodes, and then combines the communities until a clear partition is obtained. In applications such as a computer‐generated network, Ucinet networks, and Chinese rural‐urban migrants' social networks, the algorithm can achieve higher modularity and greater speed than others in the recent literature. © 2007 Wiley Periodicals, Inc. Complexity 12: 53–60, 2007     

Pilot Study on Exhaled Breath Analysis for a Healthy Adult Population in Hawaii

Fast diagnostic results using breath analysis are an anticipated possibility for disease diagnosis or general health screenings. Tests that do not require sending specimens to medical laboratories possess capabilities to speed patient diagnosis and protect both patient and healthcare staff from unnecessary prolonged exposure. The objective of this work was to develop testing procedures on an initial healthy subject cohort in Hawaii to act as a range-finding pilot study for characterizing the baseline of exhaled breath prior to further research. Using comprehensive two-dimensional gas chromatography (GC×GC), this study analyzed exhaled breath from a healthy adult population in Hawaii to profile the range of different volatile organic compounds (VOCs) and survey Hawaii-specific differences. The most consistently reported compounds in the breath profile of individuals were acetic acid, dimethoxymethane, benzoic acid methyl ester, and n-hexane. In comparison to other breathprinting studies, the list of compounds discovered was representative of control cohorts. This must be considered when implementing proposed breath diagnostics in new locations with increased interpersonal variation due to diversity. Further studies on larger numbers of subjects over longer periods of time will provide additional foundational data on baseline breath VOC profiles of control populations for comparison to disease-positive cohorts.     

我国城镇居民生活质量的评估研究

本文构建能全面客观反映城镇居民生活质量的指标体系,通过主成分分析的方法以第一主成分对各地区城镇居民生活质量进行综合评估,通过因子分析用各个公共因子反映地区特征,以了解各个方面的优势与差距,并由此对提高居民生活质量提出若干对策和建议。     

Bioenergy Systems Planning Using Location–Allocation and Landscape Ecology Design Principles

Rural energy planning is a nexus of sustainable development issues, particularly the sustainable utilization of biomass resources, on which rural parts of the developing world remain critically dependent. A landscape based rural bioenergy planning framework is presented, which is based on location–allocation and landscape ecology principles and considers both domestic and commercial energy demands and energy flows, as well as the landscape impact of the required bioenergy production zones. p-median modelling principles underly the location–allocation formulation. Optimized bioenergy landscape designs are presented, which illustrate both accessibility and landscape ecology objectives.     

乡村振兴与乡村旅游时空耦合特征分析——以浙江省为例

乡村振兴与乡村旅游的良好耦合有利于乡村资源要素的整合, 在美丽乡村建设的同时带动乡村经济健康发展. 本文构建了乡村振兴与乡村旅游发展水平评价指标体系, 利用熵值法和线性加权平均法得出浙江省整体及11个地级市两大系统综合发展水平, 借助耦合协调模型, 分析两大系统耦合协调程度. 结果表明 (1)2011—2020年浙江省两大系统综合发展水平处于波动上升状态, 耦合协调水平由低水平协调逐步过渡到良好协调; (2)浙江省乡村振兴发展水平相对较高, 属于乡村振兴主导型发展模式; (3)浙江省各地级市两大系统发展水平以及耦合协调水平都具有明显的空间差异性; (4)乡村基础设施建设、各地级市旅游资源丰度、旅游文化服务功能以及人才引入等是影响浙江省各地级市两大系统综合发展水平以及耦合协调程度的主要因素.     

农村剩余劳动力估算的工日法的分析与改进研究

在现有文献研究的基础上,对估算农村剩余劳动力的工日法又作了进一步深入研究,给出了该方法的计算模型,指出了工日法存在的不足,即没有考虑农业生产的季节性、阶段性和气象因素对农业生产的影响.按照工日法估算的农业劳动力需求数量与农业生产实际需要量有较大的偏差,会出现在作业高峰期劳动力不够用,在农闲季节,本无劳动任务,却认为在劳动的情况,并通过示例计算,对其进行了验证.在此基础上,研究给出了一种改进方法,即作业高峰期法,同时给出了该方法的数学模型.该方法不仅考虑了农业生产的季节性和阶段性,同时也考虑了气象因素对农业生产的影响,因此能够较好地反映农业生产实际.最后探讨了估算不同区域范围农村剩余劳动力的估算方法,同时提出了在研究全国的农村剩余劳动力数量时,应根据农业生产、地域和气候等特点,将全国划分成若干个类型区,然后在不同的区域上分别进行抽样调查,获取相应的数据,分别进行计算,最后加总得出全国的数据.而在研究一个地区或一个县的剩余劳动力则一般可不进行分区.     

中国城镇居民消费支出的多元非线性回归模型研究

以1993-2007年数据为根据,采用逐步回归方法,建立中国城镇居民消费支出的多元非线性回归模型.结果表明:影响居民消费支出的主要因素有收入、消费意愿、居住面积、商品零售价格.消费支出随着收入、消费意愿、商品零售价格的提高而提高,随着人均居住面积的增加而先增后减.而且多元非线性回归模型比线性回归模型更能准确描述客观实际结果.     

浅谈农村中学物理教师的终身教育

通过调查农村中学物理教师的终身教育现状,利用SPSS11.5 for Windows软件统计分析,从分析影响农村中学物理教师终身教育的三个因素——学校、教师和教育培训机构入手,提出有效实施农村中学物理教师终身教育的对策.     

混合图上最小-最大圈覆盖问题的近似算法

考虑一个混合图上的最小-最大圈覆盖问题。给定一个正整数k和一个混合加权图G=（V,E,A）,这里V表示顶点集,E表示边集,A表示弧集。E中的每条边和A中的每条弧关联一个权重。问题的要求是确定k个环游,使得这k个环游能够经过A中的所有弧。目标是极小化最大环游的权重。该问题是运筹学和计算机科学中一个重要的组合优化问题,它和它的变形在诸如快递配送、垃圾收集、积雪清扫等相关行业具有广泛应用。针对该问题,通过结合二分搜索和环游撕裂的技巧,首次给出了一个近似比为37/5的近似算法。