桥梁病害对桥梁设计的启示分析

现阶段,随着社会经济的飞速发展,道路基础设施的建设速度逐渐加快。同时,随着各种各样桥梁病害问题的出现,对桥梁的承载能力造成了一定程度的影响。因此,及时防治桥梁病害有助于保障桥梁的安全性。论文结合某危桥改造项目,对桥梁的病害展开研讨,对病害的产生原因进行分析,并提供实用性的桥梁设计应对方法,以保证桥梁的耐久性与安全性。     

Evaluation of the social and economic impact of carbon dioxide (CO2) emissions on sustainable mobility using cumulative ordinal models: trend odds model

In the context of environmental sustainability evaluation, grouped under climate change, health and ecosystem themes, an impact that could be investigated is the Global Warming Potential (GWP), whose sources are a multitude. In urban areas the evaluation of real vehicles emissions is an essential activity in order to suggest possible solution to local administrators. They still express the need to improve and maintain the characteristics of the breathing air at the best possible quality level. Moreover, these solutions, such as planning measures or traffic control management in respect of pollution, would be apply at different geographical levels, i.e. national, regional or urban scale. Another factor to be investigated is the effect of technologies and emission control systems to comply more stringent limits (Euro 4/5/6) and improve air quality to a lower environmental impact. GWP, indicator of climate change, is measured in terms of CO₂ equivalency emission values variable. To perform this activity an experimental campaign was carried out with several vehicles from different manufacturers and with a wide variety in terms of mass, power, engine displacement and type approval technology. The experimental plan includes some repetitions of the urban section in Naples city centre.The purpose of this paper is twofold: first, to provide a strategy on the choice of a logistic model with ordinal data and with trend, and, second, to evaluate the usefulness of such models for environmental sustainability (CO₂ and other vehicular pollutant emissions), with particular emphasis on model formulation, the interpretation of model coefficients, and the implications of such models.     

Ex-post full surplus extraction,straightforwardly

Consider an estimate of the common value of an auctioned asset that is symmetric in the bidders’ types. Such an estimate can be represented solely in terms of the order statistics of those types. This representation forms the basis for a pricing rule yielding truthful bidding as an equilibrium, whether bidders’ types are affiliated or independent. We highlight the link between the estimator and full surplus extraction, providing a necessary and sufficient condition for ex-post full surplus extraction, including the possibility of independent types. The results offer sharp insights into the strengths and limits of simple auctions by identifying the source of informational rents in such environments. Harstad acknowledges hospitable accommodation by the Fuqua School of Business, Duke University, and the Olin School of Business, Washington University in St. Louis, during parts of this research. We are grateful for comments and suggestions from Richard McLean and Jeroen Swinkels.     

基于生态学思考的小城镇新区规划设计新理念

基于生态学的思考,小城镇新区规划设计应树立五个新理念:深化人本思想、突出文化内涵、注重景观设计、树立超前意识、发扬务实精神。新理念在实践过程中体现在:营造人性化的小城镇新区、塑造地方性的小城镇特色、打造园林式的小城镇景观、构造灵活性的小城镇格局、绘就实用性的小城镇蓝图。     

R＆D、R＆D溢出、内生增长和内生收敛

根据强调知识与技术创新、知识与技术溢出重要性的当代内生增长理论，本文建立了一个将R＆D和R＆D溢出与资本积累之间、R＆D和R＆D溢出与总产出增长之间直接关联起来的动态模型。面板数据协整检验实证分析结果表明R＆D和R＆D溢出与资本积累之间、R＆D和R＆D溢出与总产出增长之间分别存在显著的正面长期协整关联。进一步的分析表明，R＆D与资本积累之间、R＆D与总产出增长之间分别存在显著的长期双向格兰杰因果关系。由此观知，R＆D乃长期经济增长源泉之所在。另一方面，尽管资本积累或总产出增长并不格兰杰导致R＆D溢出，证据表明R＆D溢出格兰杰导致资本积累和总产出增长。这种由R＆D溢出到资本积累和总产出增长的单向格兰杰因果关系意味着尽管知识与技术的跨国传播并非必然发生。其实为世界经济增长的重要动力。     

Societal preferences for fertility treatment in Australia: a stated preference discrete choice experiment

Objective: To investigate preferences for fertility treatment from the Australian general population with the aims of calculating the willingness to pay in tax contribution for attributes (characteristics) that make up treatment and for an “ideal” fertility treatment program. We also assessed whether willingness-to-pay varies by the relationship status or sexual orientation of the patient.

Methods: A stated preference discrete choice experiment was administered to a panel of 801 individuals representative of the Australian general population. Seven attributes of fertility treatment under three broad categories were included: outcome, process, and cost. Attributes were identified through published literature, focus group discussions, expert knowledge, and a pilot study. A Bayesian fractional experimental design was used, and data analysis was performed using a generalized multinomial logit model. Further analyses included interaction terms and latent class modeling.

Results: Six of the seven attributes influenced the choice of a treatment program. Under process attributes, individuals preferred: continuity of care of clinic staff, where patients are seen by the same doctor but different nurses at each visit; “alternative” treatments being offered to all patients; and onsite clinic counseling and peer-support groups. Personalization and tailoring of the treatment journey were not important. Among outcome attributes, the improved success rate of having a baby per cycle and significant side-effects were considered important. Cost of treatment also influenced the choice of treatment program. Individual preferences for fertility treatment were not associated with patients’ relationship status or sexual orientation. Latent class modeling revealed sub-groups with distinct fertility treatment preferences.

Conclusion: This study provides important insights into the attributes that influence the preferences of fertility treatment in Australia. It also estimates socially-inclusive willingness-to-pay values in tax contributions for an “ideal” package of treatment. The results can inform economic evaluations of fertility treatment programs.     

生态农业模式构建与应用——以广饶县为例

本文从农业可持续发展、资源永续利用的原则出发,探讨了构建生态农业模式的原则,以山东省广饶县为例,系统分析了在该县构建和应用生态农业模式的优势条件和制约因素,具体论述了适合广饶县发展的三种生态农业模式:农—牧—沼型、上粮下渔型和草—畜—乳型生态农业模式。     

非农化经营与农业上市公司经营绩效——理论分析与实证检验

我国农业上市公司非农化经营现象甚为严重,这一现象对农业上市公司经营绩效的影响引起了社会各界的广泛关注.农业上市公司非农化经营主要可以归纳为产业层次和企业管理层次这两方面成因.农业发展不足的现实成为我国农业上市公司非农化经营取向的最大产业背景因素.文章运用农业比较利益理论、外部性理论以及多元化经营理论,形成对农业上市公司非农化经营成因和非农化经营对绩效影响的理论分析框架.通过实证分析所得出的结论是:非农化经营从整体上减损了农业上市公司经营绩效.研究认为,政府应该着力在改善农业投资经营环境和制度创新上下功夫,才可能真正引导农业上市公司专注于农业上来;同时认为,目前农业上市公司主要应当实施农业专业化经营战略,在条件具备的情况下才实施与主业相关的多元化战略,现阶段应尽量避免非相关多元化经营.     

模块化设计中的价值管理

模块化设计作为新产业结构的本质特征,实际上是工业时代产品标准化概念的延伸和发展。它既强调产品的统一性和各部分的标准化,同时又强调产品整体最优和各部分的创新性。分解组合思想是其基本思想所在,即将大系统“化整为零”,分解成为若干小系统,实现小系统局部最优和将小系统“合零为整”,使之相互协调配合,实现大系统全局最优的结合。文中运用系统评价的价值分析方法,以功能为核心对系统进行分解,使具有协同作用的模块的组合形成功能组合,达到整体功能最优,从而实现功能放大的效果,同时通过个别模块的替代或特定模块的升级带动整体功能的替换或功能水平的提升。由此看来,将价值管理应用于模块化设计中,为多样化时代的标准化工作提供了新的技术管理方式和思维方式。