Decision-Making Model for Farmer Choosing Land Use Based upon Dynamic Optimization Theory

Using the dynamic optimization theory, we described a decision-making model for farmer choosing land use when there are several different kinds of uses for land. To obtain an empirical model that could be easily applied, decision rules for farmer with a single static expectation were given.     

离心泵机械密封故障分析

根据生产实际中遇到的离心泵用机械密封的各种故障进行统计分析,详细总结了产生故障的原因,并提出了解决方案,使用户能够在选型、安装、使用方面对机械密封有一个全面的了解,对提高机械密封的使用性能有一定帮助.     

广西高速公路建设节约集约用地的几点思考

文章以中国当前高速公路的迅速发展同土地资源紧缺之间的矛盾为切入点,以灌阳至平乐高速公路为依托工程,提出了高速公路建设节约集约用地的基本内涵,指出了目前高速公路建设节约集约用地中尚存的问题,并从多个角度提出了改进高速公路节约集约用地现状的技术措施。     

浅谈立交改扩建方案设计

受交通量的发展和路网新布局的形成等因素影响,已建的许多互通式立交面临改扩建。文章以重庆江津西彭互通式立交在原有A型单喇叭三路互通立交基础上改建成四路立交的工程为例,阐述了改扩建立交在选型和设计过程中的思路,总结了一些改扩建立交方案选择的原则,供同行参考。     

用地性质与线路区位对社区公交的影响研究

社区公交的开通可有效缓解乘客出行的"最后一公里"问题,合理的站点布局可提高社区公交的客流量、促进公共交通发展。基于交通实地调查、SP调查和RP调查,对郑州市社区公交现状进行分析,分别对出行者的性别、年龄、家庭人口数、月收入、职业、出行目的进行特征分析。考虑用地性质和线路的区位影响,分别对社区公交的客流量和乘坐社区公交前使用的交通方式进行研究,分析其对社区公交的站点布设、两站点间的距离、发车间隔和发车频率等的影响,为社区公交的布设提供依据,增加社区公交的竞争力,更好地满足社区居民的出行需求。     

The importance of the use phase on the LCA of environmentally friendly solutions for asphalt road pavements

In order to assess sustainability of products and processes, different methodologies have been developed and used in the last years. In the road pavement construction area, most methodologies used for Life Cycle Assessment (LCA) are essentially focused in the construction phase. The present paper analyses the importance of the use phase of a road in the LCA of different paving alternatives, namely by evaluating energy consumption and gaseous emissions throughout the road pavement’s life. Therefore, a new LCA methodology for road pavements was developed, and the results of its application to a case study involving the construction of alternative pavement structures are discussed. The study intends to assess the influence of using more sustainable paving construction alternatives (asphalt recycling vs. conventional asphalt mixtures), and/or different surface course materials (which have a higher influence on the rolling resistance and, therefore, affect the performance during the use phase). The LCA results obtained for this case study showed that the reductions in energy consumption and gaseous emissions obtained during the use phase, for pavement alternatives with a lower rolling resistance surface course, are higher than the total amount of energy consumption and gas emissions produced during construction. It is therefore clear that some improvements in the characteristics of the surface course may have an effect over the road use phase that will rapidly balance the initial costs and gas emissions of those interventions. The LCA results obtained also showed that the sustainability of pavement construction may also be improved using recycled asphalt mixtures.     

The impacts of mass transit on land development in China: The case of Beijing

Land development impacts of mass transit have long been studied in the developed economies. Yet relatively little is known by the outside world about the Chinese experience due to China's rather short history in the development of modern mass transit and land/property market. This paper attempts to fill the gap by presenting evidence from China, with a detailed case study of Beijing. Selecting three newly built suburban transit lines in Beijing, the study examined land development context and estimated hedonic housing price models to measure the proximity premiums associated with these three lines. The empirical evidence in Beijing, one of the first tier mass transit cities in China, shows that investments in mass transit can have significant and positive impacts on land development. Properties with transit proximity enjoy sizable price or value premiums. The study also confirms the international experience: transit impacts on land development are unlikely to occur automatically; they rely greatly on supportive regional and site conditions. Integrated planning and design for mass transit and land development are critical to expand and maximize the return of transit investments.     

电子邮件业务在Inmarsat-C系统中的应用

阐述了在陆地用户和Inmarsat-C海上移动用户之间实现电子邮件的方式,以及通过互联网和地面站接续网络实现灵活有效通信的方法。     

GPS-RTK技术在高速公路征地测量中的应用

文章介绍了GPS-RTK全球定位系统实时动态相位差分定位技术的概念、组成及特点,分析了传统征地测量方法存在的问题,阐述了利用GPS-RTK技术进行征地测量的前期准备工作、外业及内业工作内容,并通过对比分析,指出了GPS-RTK技术在速度、精度、可追溯性、审计、可控性方面的优势。     

CO2 emissions: Are land-use changes enough for California to reduce VMT? Specification of a two-part model with instrumental variables

With vehicle miles of travel increasing at a faster pace than population, one strategy being actively pursued by both state and local governments is compact development. California recently passed legislation that aggressively promotes sustainability by endorsing and rewarding compact development. Likewise, the California Air Resources Board has set a statewide reduction target of 5MMT of greenhouse gas reductions from land use, based largely on achieving compact development patterns. In this paper, we use a multivariate two-part model with instrumental variables, which corrects for residential location self-selection bias. We use a much larger and more geographically representative travel survey on household travel patterns and socio-economic characteristics than represented in previous California studies; this allows us to robustly consider other influences on travel. Our results indicate that, all else equal, a 10% in residential density would reduce VMT by 1.9%. This elasticity is larger than the reported in previous econometric studies for the US, and specifically for California. However, as we show, the magnitude of this impact is still low considering reasonable ranges for policies aimed to increase residential density.