经济收敛理论与检验方法研究综述

在大量文献研究的基础上,对收敛问题的产生及收敛概念的发展作了全面概括,并对绝对收敛、条件收敛、俱乐部收敛和σ收敛作了深入辨析,对各种识别方法作了全面归纳。归纳了对世界大多数国家和地区数据所作识别的结果。还从收敛理论与传统理论的冲突与协调方面作了深入分析。最后对近年收敛研究的深化与扩展研究的趋势作了概括。     

城口县农村集体经济发展新模式论析

农村集体经济是实现我国农村产业发展和农民共同富裕的有效途径,是完善社会主义市场经济体制发展的内在要求.秦巴山区城口县在家庭承包制下,不断探索和创新农村集体经济实现形式,建立起以"农户入社、社企合作"的新型农村集体经济组织形式——双层股份合作制.通过对双层股份合作制模式的分析,认为它是一种既实现效率又兼顾公平的新型农村集体经济组织形式,对国家实现扶贫攻坚和地区脱贫致富有着重要意义.     

中国单身女性的困境: 多元交叉的社会压力和歧视

随着中国单身人口比例的上升,单身人群特别是单身女性群体受到了社会各个层面的关注。目前国内对单身女性的研究主要通过深度访谈来探讨单身未婚女性的身心和生活状态,缺乏系统的理论观照,且访谈样本又大都局限于大城市的中产阶层单身未婚女性,因而限制了研究成果的代表性。从交叉性理论出发,分析中国单身女性面临的宏观(儒家文化和人口调控压力)、中观(媒体的形象控制和代际压力)和微观(性别歧视、年龄歧视和单身歧视)的多元交叉压力和歧视,厘清目前单身女性所受到的压力和歧视,从不同阶层单身女性的需求出发,才能为她们提供切实有效的帮助,并有助于解决目前我国单身人口比例上升的问题,缓解人口老龄化的压力。     

澳大利亚远程高等教育的特点及对中国的启示

在网络技术发达的时代,远程高等教育是世界高等教育发展的必然趋势。中国为了跟上时代的步伐,有必要大力发展远程高等教育。由于中国远程高等教育发展的时间短,技术水平低,因此有必要向发达国家学习。澳大利亚具有发展远程高等教育的悠久历史,发展水平也处在世界前列。因此,借鉴澳大利亚远程高等教育的发展经验,对中国远程高等教育的发展具有重要的启示。     

Survival in the U.S. petroleum refining industry

Of the 324 petroleum refineries operating in the U.S. in 1982, only 149 were still in the hands of their original owners in 2007. Using duration analysis, this paper explores why refineries change ownership or shut down. Plants are more likely to ‘survive’ with their original owners if they are older or larger, but less likely if the owner is a major integrated firm, or the refinery is a more technologically complex one. This latter result differs from existing research on the issue. This paper also presents a split population model to relax the general assumption of the duration model that all refiners will eventually close down; the empirical results show that the split population model converges on a standard hazard model; the log-logistic version fits best. Finally, a multinomial logit model is estimated to analyze the factors that influence the refinery plant's choices of staying open, closing, or changing ownership. Plant size, age and technology usage have positive impacts on the likelihood that a refinery will stay open, or change ownership (rather than close down).     

干渴的梯田:王金庄村水资源的分配与管理

河北省涉县旱作梯田系统是中国重要农业文化遗产。 其核心保护区域王金庄村位于太行山东麓,地形条件复杂,缺土少水、旱涝频发,但梯田系统因独特的人文智慧延续近八百年而不衰。 文章以水为切入点,阐释水资源短缺情形下百姓的生存逻辑与生计策略。 村庄作为一个系统对自然环境进行着补救性适应、抗风险适应与常态适应,这些文化适应性举措使旱作梯田的可持续发展得以实现,也展示出古老农耕智慧对于农业永续发展的重要意义。 因此,保护农业文化遗产不仅是对传统文化与社会系统的保护,更是对现代农业后果的生态补救,对农业与农村发展的现实反思,对可持续发展之路的探寻。     

Optimal designs for multivariate logistic mixed models with longitudinal data

This paper considers the optimal design problem for multivariate mixed-effects logistic models with longitudinal data. A decomposition method of the binary outcome and the penalized quasi-likelihood are used to obtain the information matrix. The D-optimality criterion based on the approximate information matrix is minimized under different cost constraints. The results show that the autocorrelation coefficient plays a significant role in the design. To overcome the dependence of the D-optimal designs on the unknown fixed-effects parameters, the Bayesian D-optimality criterion is proposed. The relative efficiencies of designs reveal that both the cost ratio and autocorrelation coefficient play an important role in the optimal designs.     

Reliability analysis of load-sharing systems with memory

The load-sharing model has been studied since the early 1940s to account for the stochastic dependence of components in a parallel system. It assumes that, as components fail one by one, the total workload applied to the system is shared by the remaining components and thus affects their performance. Such dependent systems have been studied in many engineering applications which include but are not limited to fiber composites, manufacturing, power plants, workload analysis of computing, software and hardware reliability, etc. Many statistical models have been proposed to analyze the impact of each redistribution of the workload; i.e., the changes on the hazard rate of each remaining component. However, they do not consider how long a surviving component has worked for prior to the redistribution. We name such load-sharing models as memoryless. To remedy this potential limitation, we propose a general framework for load-sharing models that account for the work history. Through simulation studies, we show that an inappropriate use of the memoryless assumption could lead to inaccurate inference on the impact of redistribution. Further, a real-data example of plasma display devices is analyzed to illustrate our methods.

     

施工企业投标优化的问题与对策

通过对某大型施工企业多个铁路、公路施工项目部的调查，总结了企业当前投标优化方面存在的问题。针对企业以铁路、公路项目为主业的特点，提出了优势项目滚动发展、建立有效激励制度、做好投标准备、优化施工组织设计、应用报价技巧等优化对策。对于施工企业改善市场经营效果，提高中标质量，增加项目盈利有重要的借鉴作用。     

Internal consistency of demographic assumptions in the shared socioeconomic pathways

A new set of alternative socioeconomic scenarios for climate change researches—the shared socioeconomic pathways (SSPs)—includes for the first time a more comprehensive set of demographic conditions on population, urbanization, and education as the central scenario elements, along with other aspects of society, in order to facilitate better analyses of challenges to climate change mitigation and adaptation. However, it also raises a new question about the internal consistency of assumptions on different demographic and economic trends under each SSP. This paper examines whether the interactions between the demographic and economic factors implied by the assumptions in the SSP projections are consistent with the research literature, and whether they are consistently represented in the projection results. Our analysis shows that the interactions implied by the demographic assumptions in the SSPs are generally consistent with findings from the literature, and the majority of the assumed relationships are also evident in the projected trends. It also reveals some inconsistency issues, resulting mainly from the use of inconsistent definitions of regions and limitations in our understanding of future changes in the patterns of interactions at different stages of socioeconomic development. Finally, we offer recommendations on how to improve demographic assumptions in the extended SSPs, and how to use the projections of SSP central elements in climate change research.