城际铁路单箱双室预制箱梁静载试验研究

文章以海南东环铁路万宁制梁场整孔箱梁静载试验为基础,对城际铁路单箱双室新型预制梁体静载弯曲试验和梁端静载试验进行阐述,重点对静载加载形式、试验测点布置和测试结果进行了描述,最终通过应力应变实测值与理论值的比较,提出试验结论和建议,并对单箱双室整孔箱梁的设计、施工工艺、施工质量以及箱梁的抗裂性能、梁端受力性能进行验证。     

A comparison of alternative technologies to de-carbonize Canada's passenger transportation sector

Using a full systems model of Canada's economy, six alternative scenarios to de-carbonize the personal passenger vehicle fleet are compared to a business as usual non de-carbonized scenario in terms of greenhouse gas emissions, trade disposition of energy commodities, and the physical resources required for energy production. Three scenarios are analyzed to compare the impacts of increasing either ethanol 85, hydrogen, or electricity powered vehicles into the vehicle fleet, with each starting to penetrate the light vehicle stock in 2010 to reach 100% of the new vehicle market by 2050. For each of these three scenarios, we then construct a variant scenario that considers the additional effects of de-carbonizing electricity production. With a de-carbonized electricity sector, net emission reductions are 29% for ethanol 85, and 31% for both hydrogen and electricity. When considering the transportation sector only, net emission reductions equal 13% for ethanol 85, and 14% for hydrogen and electricity. However, although the ethanol scenario results in the lowest reduction in total emissions, it has significant impacts on other parts of the physical resource base. By the time ethanol reaches 5% of the fuel mix in 2015, domestic consumption of grains increases by 20%, in turn impacting crop trade disposition. At this point, emissions are reduced by less than 0.5%, owing to the fossil fuels required since most ethanol is still grain based. By 2050 it is projected that almost all ethanol will be cellulose based, generating a more significant emission reduction but in turn requiring potentially unsustainable amounts of crop residue.     

Determinants of a Digital Divide in Sub-Saharan Africa: A Spatial Econometric Analysis of Cell Phone Coverage

This paper investigates the determinants of disparities in coverage by cell telephone systems in Sub-Saharan Africa. It uses a spatially disaggregated probit for over 990,000 grid cells with adjustments for spatial autocorrelation. Determinants include potential market size (population); cost factors related to accessibility (elevation, slope, distance from a main road, and distance from the nearest large city); and competition policy. Estimates indicate significant results for the supply–demand variables, and very strong results for the competition policy index.Simulations suggest that a generalized improvement in competition policy could lead to huge improvements in cell phone area coverage, and to an overall coverage increase of nearly 100%.     

月季色素与菠菜色素敏化太阳能电池的光电性能研究

本文从月季与菠菜中提取色素制成染料敏化太阳能电池所需的染料。通过对月季与菠菜所制备成的染料进行紫外-可见吸收光谱测试,分析了提取的月季与菠菜中染料的主要成分。对月季与菠菜染料用于敏化太阳能电池进行光电性能测试和量子效率测试,结果表明用月季色素做为染料敏化太阳能电池的光电性能较好。     

应尽快启动燃料电池叉车的研发

石油资源的日益紧缺和环境污染的日益加重,经过科技界和产业界几十年的艰苦努力,燃料电池、混合动力等新一代机动车辆驱动方式已接近实用,能否将其移植到叉车上?文中从必要性和可行性两个方面讨论了燃料电池叉车的开发问题。     

Assessing the Legitimacy of Stem Cell Research: An Instrumental Valuation Principle Approach

Research on embryonic stem cells has elicited much public and political debate. By promoting the use of the Instrumental Valuation Principle, it is argued here that institutionalists can offer a framework for policy analysis that ensures that the debate on stem cell research is informed by the instrumental use of knowledge and that it is not controlled by upper-level hegemonic powers. Our contention is that the first decade following the initial harvesting of human embryonic stem cells (1998-2008) in the United States was characterized by institutional and policy responses that created a non-deliberative environment that hindered the process of instrumental valuation of stem cell research. This paper concludes that the current conditions of limited corporate involvement are favorable toward a democratic discussion of the legitimacy of stem cell research, but this will require overt challenges to political elites' attempts to control the creation and flow of instrumental knowledge on stem cell research.