煤炭资源对县域经济发展的正负效应分析及转化建议——以安徽省涡阳县为例

以安徽省涡阳县为例,从分析煤炭资源开采对县域经济发展的正负效应影响和辩证关系转化的角度,提出煤炭资源对涡阳县域经济可持续发展的具体建议。     

Conditions for a 100% renewable energy supply system in Japan and South Korea

In the wake of the Fukushima nuclear accident, alternative energy paths have been discussed for Japan, but except for a few studies the assumption is usually made that Japan is too densely populated to be suited for a near-100% sustainable, indigenous energy provision. The studies emphasizing renewable energy have proposed the use of photovoltaic power as the main source of electricity supply, in combination with diurnal battery storage and supplemented by other renewable sources such as wind, hydro, and geothermal power. Here, an alternative approach is explored, with wind and derived hydrogen production as the main energy source, but still using solar energy, biofuels, and hydropower in a resilient combination allowing full satisfaction of demands in all sectors of the economy, i.e., for dedicated electricity, transportation energy as well as heat for processes and comfort. Furthermore, the possible advantage of establishing a regional energy system with energy interchange and coordinated management of the mix of renewable energy resources across a wider region is discussed. As the closest neighbor, the energy system of South Korea is considered, first regarding the possibility of a similar full renewable energy reliance, and then for possible synergetic effects of connecting the Korean and the Japanese energy systems, in order to be able to better cope with the intermittency of renewable energy source flows.     

土地质量对农业劳动生产率的影响——来自六省县级数据的经验证据

本文利用国土资源部农用地分等定级与估价项目的土地自然质量指数数据,结合2004年的县级统计数据,建立改造的C-D生产函数,通过多元回归分析定量考察了土地质量对农业劳动生产率的影响。最终得到如下研究结果:对所用的县,土地质量指数每增加1%,农业劳动生产率增加0.336%;分地区的结果显示,土地质量和化肥投入在东部地区为替代关系,在西部地区为互补关系。研究结论:土地质量在很大程度上影响着农业劳动生产率,应加强对土地质量的保护和改善。     

建筑施工中临边高处坠落危险源影响空间建模

将建筑施工中临边坠落的特性模型化,对于预防建筑施工中伤亡事故具有重要的意义。在分析人或物临边高处坠落事故特点的基础上,给出施工工作面内外2种危险源影响空间范围的定义及其数学表达函数,构建相应的危险源影响空间中危害能量分布的数学模型,提出它对人体不同部位伤害程度的评估分析思路,并在大面积碰撞和小面积碰撞2种情况下,建立该危害能量对人体头枕部伤害程度的评估分析方法。通过上海某个6层框架结构教学楼案例,对上述数学模型和评估分析方法进行验证。这为在进行施工计划安排时,考虑危险源影响空间的影响,降低安全事故发生的可能性创造条件,也为安全事故事前预防提供新思路。     

Order 636 and the U.S. natural gas industry

An intent of the U.S. Federal Regulatory Commission's Order 636, promulgated in April 1992, was to promote competition and efficiency in the transportation sector of the natural gas industry. Additionally, the Order altered the roles of the traditional players in the industry by increasing not only their options for purchase and sale of natural gas, but also their risks. Increased options have the potential of increasing competition and efficiency, not only in the transportation sector, but also in the distribution sector. This paper examines impacts of Order 636. Using annual, aggregate, U.S. price data, a Wilcox rank sum test is employed to test for statistically significant differences between the pre- and post-636 eras. Results indicate median revenues attributable to the transportation sector have declined since the implementation of Order 636.¹ Although there are naturally a number of factors that may affect transportation revenues, the decline in median price can be attributed, at least in part, to increased competition, increased efficiency, or both. At this level of aggregation the effects can not be segregated. Results also indicate that although decreased costs of transportation have at least partially been passed on to final consumers, local distribution companies have not significantly altered their business practices when dealing with customers.     

From the enclave to the city: the economic benefits of immigrant flexibility

While much attention has been paid to the entrepreneurial “base” of the ethnic economy, the enclave is primarily composed of thousands of hourly employees working in small co-ethnic or multi-ethnic immigrant firms. The US economy benefits from over 10?billion dollars in taxed income and wages from immigrants whose social security numbers do not match up with their employee tax identification numbers. Multiple mismatches and misinformation about immigrants (from an economic, cultural, and political standpoint) demonstrate the need to understand the unique potential of immigrant communities in facilitating urban growth. Koreatown in Los Angeles, an ethnic enclave economy that is also a central business district for many immigrant workers, is one emergent example of new types of flexibility around citizenship status and semi-formal jobs as they are negotiated on a daily basis in the neighbourhood. Previous studies of the ethnic enclave have maintained that there is a singular importance to the co-ethnic network (Korean to Korean, or Cuban to Cuban, for example), and yet this traditional characterisation of the ethnic enclave does not hold true in most urban ethnic enclaves, which include multiple ethnic groups working side by side. Interviews with Korean and Latino workers demonstrate the ways in which people (including undocumented individuals) contribute to the local economy, and informally communicate in neighbourhoods and cities to build a broader social and economic network outside of enclave boundaries.     

Food production in the city: (re)negotiating land,food and property

This paper addresses issues of access to land for food production in Toronto by offering fresh perspectives on urban agriculture in the neo-liberal city of the global north. It examines attempts to scale up urban agriculture that emphasise changing the relationships between land access, property and new collaborative relationships among different stakeholders. These initiatives involve renegotiating access to land for growing food between private property owners and landless growers, concomitant shifts in control over valued resources and commercialisation. These shifts are often based on relations of trust within a sharing economy rather than public battles over political decisions to develop urban agriculture lands. Growing food on private lands in the city is political in challenging taken-for-granted ideas and practices of property and urban agriculture. New approaches offer options for training and income, as well as expanding the land base for urban agriculture. Small-scale farming projects are affirmative political manoeuvres. They challenge urban residents to consider land for food production across the categories of public and private property. We document three approaches that challenge current property relations: temporary use of a development site through “soft” squatting; redesignating suburban backyards for farmer training and community-based and private food production; and garden sharing of private home backyards for urban food production and commercial growing. Such initiatives articulate alternative visions of sustainability and food security that rely on principles of collaboration and a sharing economy that challenge prevailing notions of property ownership and food security.     

海河流域社会经济发展对河流水质的影响

海河流域社会经济快速发展,主要河流水质恶化.本文基于海河流域人口规模、经济产值和土地利用变化过程,结合河流社会经济发展指标和水质变化统计分析,从流域废污水排放和水资源利用等角度分析社会经济对水环境影响机制.研究表明,流域人口规模大幅增长、工业生产强度大幅提高,工业聚集区由北京-天津地区扩展到北京-天津-唐山、石家庄、聊城-德州等地区,导致海河流域工业废水和生活污水排放规模迅速上升,成为河流水质恶化直接驱动力.城市扩张是流域土地利用变化最显著特征,近30年来城市用地面积增加85%,北京-天津-唐山城市群规模扩大,造成流域水资源开发利强度加剧,降低河流自净缓冲能力.因子分析表明,流域影响河流水质因素分解为农村、城市和自然等3个方面,其中城市化过程和农村社会经济发展对河流水体污染物浓度水平影响非常显著.     

我国能源消耗对人群PM2.5暴露水平的随机影响效应分析

能源燃烧产物是PM2.5暴露水平提高的重要因素,燃烧不同种类的能源对PM2.5形成的影响机理不同,但各类能源消耗量对人群PM2.5暴露水平的影响程度尚不明确.基于2003-2010年的PM2.5质量浓度与煤炭、焦炭、原油、汽油、煤油、柴油、燃料油、天然气和电力消耗数据组成的面板数据,建立了不同种类能源消耗影响我国人群PM25暴露水平的随机效应模型.结果表明,我国2003-2010年多数省(市、自治区)的年均PM2.5质量浓度超过了世界卫生组织的标准.在研究时间段内,不同种类能源消耗量对人群PM2.5暴露水平的影响具有较大差异,煤炭、焦炭、汽油和煤油消耗对人群PM2.5暴露水平具有正影响,其中,正向影响最大的为焦炭消耗量,表明工业消耗焦炭对形成PM2.5的促进作用比较明显;与焦炭消耗量具有相近的影响效果的因素是汽油消耗,表明改进机动车和航空燃油技术同样非常重要;原油、柴油、燃料油、天然气和电力消耗对人群PM2.5暴露水平具有负影响,其中负向影响最大的为电力消耗量,表明电力作为一种清洁能源,有利于降低人群PM2.5暴露水平.     

Minimum ignition energy of mixtures of combustible dusts

Most industrial powder processes handle mixtures of various flammable powders. Consequently, hazard evaluation leads to a reduction of the disaster damage that arises from dust explosions. Determining the minimum ignition energy (MIE) of flammable mixtures is critical for identifying possibility of accidental hazard in industry. The aim of this work is to measure the critical ignition energy of different kinds of pure dusts with various particle sizes as well as mixtures thereof.The results show that even the addition of a modest amount of a highly flammable powder to a less combustible powder has a significant impact on the MIE. The MIE varies considerably when the fraction of the highly flammable powder exceeds 20%. For dust mixtures consisting of combustible dusts, the relationship between the ignition energy of the mixture and the minimum ignition energy of the components follows the so-called harmonic model based upon the volume fraction of the pure dusts in the mixture. This correlation provides results which show satisfactory agreement with the experimental values.