CNG加气站固定储气设施的防火间距研究

CNG加气站的安全间距与城市安全及土地利用密切相关,为在满足安全要求的前提下降低安全间距,提高土地利用率,对CNG加气站的防火间距进行了研究。基于Chamberlain模型,对CNG加气站内固定储气设施发生燃气泄漏燃烧的热辐射进行数值分析,结合地下抗爆泄压式新型固定储气设施的研究成果,利用Matlab对不同形式的固定储气设施发生燃气泄漏燃烧事故时的热辐射情况做出相应的数值计算。计算结果表明,新型的固定储气设施(技术)可以有效地缩小其防火间距,提高CNG加气站的土地利用率。     

PPP模式在城市轨道交通领域的应用研究

分析PPP模式的主要特点及适用于城市轨道交通工程的制约因素与适用优势,提出了充分发挥市场化运作、完善运用PPP模式法规政策、深化PPP开发模式拓宽融资渠道、提升沿线综合开发土地价值4方面关键控制要点,对促进PPP模式深化转型与轨道交通建设适用性选择具有一定参考指导作用。     

城市轨道交通地下车站机电系统造价指标分析

随着经济和社会发展,我国城市轨道交通建设已进入快速发展阶段,如何有效控制投资成为制约轨道交通可持续发展的关键因素。本文结合城市轨道交通地下车站机电工程设计内容,以佛山某轨道交通线路为例,对地下车站机电工程的造价进行分析,得出不同车站机电工程经济指标,并找出影响车站机电工程造价的关键因素,为后续工程投资估算、设计概算编制及合理确定工程项目造价提供借鉴。     

企业R&D投入影响因素——基于企业生命周期视角的实证检验

以中国A股主板制造业上市公司为样本,实证检验生命周期不同阶段企业规模、债务水平、国有控股、股权集中度、管理层持股、董事长与总经理两职设置状况与R&D投入的关系,研究结果证实：大企业比小企业更有利于R&D投入;负债对R&D投入具有制约作用;股权集中有利于R&D投入。国有控股、管理层持股、董事长与总经理两职设置状况与R&D投入的关系受企业生命周期的调节,在企业成长和成熟阶段,国有控股不利于R&D投入,而在企业衰退阶段,国有控股有利于R&D投入;在企业成熟阶段,管理层股权激励不利于R&D投入,而在衰退阶段,管理层股权激励对R&D投入有促进作用;在企业成长阶段,“两职”合一可能有利于R&D投入,在成熟和衰退阶段,“两职”分离更有利于R&D投入。     

The effect of spatial variables on the economic and environmental performance of bioenergy production chains

The aim of this paper is to understand the impacts of spatial variables on the performance of bioenergy production chains (BPCs). Even though the strong debates continue on the use of first generation biomass for bioenergy production, many countries continue to utilize it as an alternative energy source. Several studies have been carried out on biomass transformation efficiency, on environmental impacts of using crop in biofuel production, and on its negative effects on increasing food prices. However, less attention has been paid to the role played by the spatial variables on the performance measures of BPCs.In this paper, we analyse how three spatial variables, i.e. cultivation area size, land dispersion, and accessibility to cultivation areas, can affect the performance of energy-balanced BPC, which produces its own electric and thermal energy demand. The chain is represented as a network of processes, where all inputs and outputs are geographically referred and analysed in a theoretical case example. We propose an enterprise input-output (EIO) model, which can be used as an accounting tool to compute the main materials and energy flows-related costs and as a planning tool to evaluate the chain performance in different scenarios. Finally, the proposed model is applied to an actual case study, to investigate the opportunity to establish a sunflower-based BPC in Apulia region (Italy) and to assess its performance.Results show that higher land dispersion degree and less area accessibility levels reduce the economic and environmental performance of the BPCs. The construction of the energy-balanced chain reduces the negative environmental impacts caused by fossil energy use in the processes of the BPC. Managerial implications can also be obtained from actual case study about the biodiesel plant location decisions.     

The Value of Access to Rail Transit in a Congested City: Evidence from Housing Prices in Beijing

Using unique data sets of Beijing's congestion patterns and housing prices, I find that consumers are willing to pay significantly more for access to rail transit in more congested areas. Transit accessibility, however, offers little travel advantage outside of dense urban areas. The expansion of the metro network mitigates the costs of road congestion, creating both private and social benefits. Two policy initiatives aimed at reducing congestion are found to have achieved positive value effects. Further analysis reveals heterogeneous demand for accessibility, with wealthier residents and those owning fewer cars paying a higher premium for access to rail transit.     

某光伏电站接入电网对电压潮流的影响

光伏电站接入电网,必然会对系统电压、潮流产生影响。根据某地区周围电网的情况,给出了其光伏电站接入系统的设计方案。基于光伏发电模型实测数据掌握了光伏发电系统的出力变化,利用MATLAB软件编程进行牛顿-拉夫逊潮流计算,对比光伏电站接入前后电压、潮流变化;根据投运光伏电站数据,得到光伏电站接入电网对电压、潮流的影响。     

The capitalization of metro rail access in urban housing markets

Increasing access to public transportation (including metro rail) can help alleviate traffic congestion and address climate and environmental priorities. Living close to a metro line may be especially important in terms of providing improved commuting options. However, proximity to metro lines can also be associated with negative externalities, such as noise and crime, that may make living near a station less desirable. One way to assess the net value that residents place on metro rail access is to examine how proximity to metro lines is capitalized into house prices. Using a hedonic spatial difference-in-differences model, we analyze the impact of proximity to the stations on the Gold and Expo Lines in Los Angeles, California, on nearby house prices. Our findings suggest that the capitalization effect is heterogeneous. Some residents value living near new metro stations, while others do not. Overall, our results provide evidence that the value residents place on metro rail access varies based on their income levels and other demographics.     

Toward Closing the Loop between Infrastructure Investments and Societal and Economic Impacts

The long-term value proposition of transportation infrastructure investments can be significantly distorted if the short-term effects of spatial externalities on land use patterns, economic expansions, and migration patterns are not properly included in the analysis. Some of these effects occur over a short period of time and soon after the investment materializes, whereas others take longer and follow more steady patterns. In this article, we develop a novel dynamical model of a primal society with constructs that are specifically geared toward transportation infrastructure expansions and investments. The model quantifies the impact of these expansions on some key performance indicators and on the overall utility and production capacity of the society. We argue that traditional analytical models that work on the premises of stationary behavior and a static response of society to changes in infrastructure do not correctly capture these effects. The land use patterns and spatial expansion computed from the model are validated against existing theory on land use. Preliminary results on how to use the model for value proposition analysis are also presented using simple case studies.     

Zoning Policy Changes and the Urban Fringe Land Market

This paper examines the effect of a zoning change on the land market in McHenry County, Illinois. One question addressed is whether zoning "follows the market." It is found that, for agricultural land, zoning does tend to follow the market. In addition, the effect of land prices on land use is examined. The results here, however, are mixed. In the initial years after the zoning change, a high relative price of residential land increases the probability that a parcel will be zoned residential. However, several years later, a high relative price of residential land decreases the probability that a parcel is zoned residential. This result suggests that it may take some time for a zoning change to have a significant impact on the local land market.     

Land-Use Controls and Housing Costs: An Examination of San Francisco Bay Area Communities*

This paper reports on our efforts to gauge the effects of land use controls on housing markets. We discuss how land use controls affect land and housing markets and explain why communities use such controls to restrict development. We present the results of an econometric model created to assess the inflationary effects of land use controls on housing costs. The model is based on data assembled in the San Francisco Bay Area. The model results indicate that density controls and land availability do systematically affect the price of new housing units.     

高速铁路对沿线城市土地经济价值的影响及驱动力——以东北地区为例

高铁可达性是土地经济价值变化的重要驱动因素之一，本文以东北地区高铁地级市为对象，基于时间、经济、频次、服务的视角分析高铁影响下的沿线城市可达性，运用广义交通成本、土地价值增值模型探讨高铁通车前后沿线城市土地经济价值的变化，基于多元线性回归选取高铁可达性等相关特征变量，探讨影响高铁土地经济价值的驱动力。研究表明：高铁开通改变原有辽宁可达性向吉林、再向黑龙江递减的趋势，及原有沈阳经济区可达性优势最强、沿海经济带与吉林中部次之、哈大齐稍弱的格局，带来黑龙江可达性改善幅度最大、辽宁强于吉林，位处边缘区位的城市可达性获得较大提升、传统的经济实力超强城市及位处线路中心区位的城市可达性改善较弱的趋势；沈阳、长春、大连与哈尔滨高铁日常可达性位于东北前列，沈阳高铁特质空间范围跨越吉林、延伸至黑龙江，为东北高铁可达服务核心，长、大、哈为其副中心；高铁广义交通成本远高于普速列车广义交通成本，哈尔滨--长春、沈阳、大连等核心区是土地经济价值增值高值区；高铁土地经济价值与高铁服务中心强度指数、日常可达性、普速列车土地经济价值呈正相关，与哈夫系数呈负相关。     

Zoning and Industrial Land Values: The Case of Philadelphia

This paper examines the market effects of zoning. Using the hedonic framework, we perform an empirical analysis that shows that lots zoned for industrial use in our study area are associated with a 58% price discount. The paper highlights the outcome of static zoning policies in a dynamic world. As the demand for industrial land in Philadelphia declined (resulting in vacancies), prices fell, but zoning was slow to adjust, therefore land conversion did not occur to re-equilibrate.     

The new competition for land: Food,energy, and climate change

The paper addresses the new competition for land arising from growing and changing demand for food when combined with increasing global demand for transport energy, under conditions of declining petro-chemical resources and the urgent need to reduce greenhouse gas emissions. The paper starts from the premise of a ‘food, energy and environment trilemma’ (Tilman et al., 2009), where all demands to expand the area of cultivated land present high risks of increasing the carbon footprint of agriculture. Having reviewed the main drivers of demand for food and for liquid transport fuels, the paper weighs the controversies surrounding biofuels arising from food-price spikes, the demand for land, and consequent direct and indirect land-use change. It suggests that we need a more complex, and geographically differentiated, analysis of the interactions between direct and indirect land-use change. The paper then reviews evidence of land availability, and suggests that in addition to technical availability in terms of soil, water, and climate, political, social, and technological factors have significantly shaped the competition for land in different global regions, particularly the three major biofuel producing ones of the USA, Brazil and Europe. This point is further developed by reviewing the different innovation pathways for biofuels in these three regions. The main conclusion of this review is firstly that any analysis requires an integrated approach to the food-energy-environment trilemma, and secondly that strategic political direction of innovation and sustainability regulation are required to bring about major shifts in agriculture leading to sustainable intensification of cultivation (Royal Society, 2009), rather than the continued expansion of cultivated area. The consequent perspective is one of considerable global variety in technologies, agricultural productive systems, and use of natural resources. This contrasts sharply with the world of a dominant global and integrated technology platform based on petro-chemicals to which we have become accustomed.     

潞宁煤业2#煤西翼扩区轨道运输大巷支护原理研究

本文通过对潞宁煤业2#煤西翼扩区轨道运输大巷进行简要介绍并对其煤层和围岩进行了物理力学性能调研分析,得出2#煤西翼扩区轨道运输大巷的顶板和两帮具有不同的围岩特性,进而提出对其轨道运输大巷及煤巷的顶板和两帮宜采用的相应锚杆支护原理。     

The roles of land tenure reforms and land markets in the context of population growth and land use intensification in Africa

This article reviews the past and potential future roles of land tenure reforms and land markets in Sub-Saharan Africa (SSA) as responses to population growth in the process of land use intensification and livelihood transformation. The farm size distribution and the existence of an inverse relationship (IR) between farm size and land productivity in SSA and the implications of this relationship for efficiency and equity are investigated. More secure property rights and removal of restrictions on land markets have the potential to create both efficiency and equity benefits, but there are high risks of elite capture of large land areas with inefficient and inequitable outcomes. This situation is the case not only in land-abundant areas but also in urban and peri-urban areas where increasingly larger proportions of people will make their living. Increasing population pressure in densely populated rural areas contributes to more rapid rural–urban migration, and creating alternative livelihood opportunities for the migrating youth population is essential to achieving economic development with social stability.     

REDD policy impacts on the agri-food sector and food security

Recent research shows that the combined contributions of deforestation, forest degradation and peat land emissions account for about 15% of greenhouse gas emissions. The REDD policy which preserves forests and values standing forests, enables substantial emission reductions. Since agricultural production and area expansion is a primary driver of tropical deforestation, REDD policies might limit the expansion possibilities of agricultural land use and therefore influence competitiveness of the agricultural sector, agricultural prices, trade patterns, agricultural production and therefore food security in the world. This paper studies the impact of REDD policies on the agri-food sector and food security with a global CGE model called MAGNET using a scenario approach. It focuses on the restrictions on agricultural land expansion within the REDD policy package. Simulation results show that REDD policies start to affect the agri-food sector in some lower developed countries if more than 15% of potentially available agricultural areas are protected from deforestation. A stringent REDD policy that protects 90% of land reserves that could potentially be used for agriculture production results in a global real agricultural price increase of almost 7.6%, and a worldwide agricultural production decrease of 1.7%. Regional differences are large, with real agricultural price changes ranging from 4% in North America to about 24% in Sub-Saharan Africa and South-East Asia. Food access rapidly deteriorates for low-income population in these regions in the case of high forest protection levels. Compensatory payments are necessary from a food security point of view if the level of forest protection increases. Our results indicate that from a food security perspective REDD policy should stop short of trying to protect more than 40% of global carbon if the compensation mechanism is not effectively implemented within REDD.     

On the Relation between Local Amenities and House Price Dynamics

This study explores the extent to which local amenities are related to house price volatility, returns and risk‐adjusted returns across 238 MSAs. We find strong evidence that high amenity areas experience greater price volatility. In regards to returns, high amenity areas experience greater (lower) real returns in appreciating (depreciating) markets. However, high amenity areas experience little to no abnormal risk‐adjusted returns. Results from the study are robust to an endogenous treatment of amenities and land supply elasticity. Overall, we conclude that the desirability of a metropolitan area is a significant channel through which land values drive house price dynamics.     

Application of game theoretic analysis to a problem in demography

"Governments in certain countries have tried over the last two decades to draw most industry to the largest cities. The effect has generally been a large increase in both the population and land area of the cities, as the nearby rural areas are taken out of agricultural production and urbanized. Where the land is especially fertile, this can represent a definite loss to the country's agricultural capabilities. By studying the Nash equilibria we show that, given political pressures, there is a very real danger that this process will continue until all, or practically all of the land has been urbanized." The geographical focus is on Colombia.     

张掖市甘州区土地利用的时空结构分异研究

土地利用变化时空分异在很大程度上都反映于土地利用结构的时空分异,描述土地类型空间结构分异最常用的方法就是比较分析不同土地利用类型在空间方位上的差异。但考虑到此方法的一些缺陷,本文在上述方法的基础上,引入了年均变化强度指数指标来描述土地利用的时空结构分异特征。为了便于比较某一研究时期土地利用变化的强弱或趋势,可计算各空间单元的年均变化强度指数,它实质就是用各空间单元的土地面积来对其年均变化速度进行标准化处理,使其具有可比性,得出各不同用地类型的时空结构分异情况,对出现这种情况的原因进行综合分析评价,从而达到全面把握土地变化规律的目的。