基于高光谱影像的三江源区不同退化程度高寒草甸分类研究

三江源地区是我国最重要的生态功能区之一。近年来,受全球气候变暖及日趋频繁的人类活动的影响,三江源地区高寒草甸生态系统退化现象明显。以三江源称多县清水河镇东北部地区为实验区,基于环境小卫星HJ\|1A HSI高光谱数据,结合不同退化程度高寒草甸地面光谱采集和样方调查,采用MLC和SAM方法对不同退化程度的高寒草甸开展了分类研究。结果表明:基于高光谱数据的不同退化程度高寒草甸采用SAM方法分类总体精度达到75%以上,证实了分类方法的可行性,基于高光谱数据分类能有效区分盖度相近、退化程度不同的草地类型,其中SAM分类结果更加精细准确,优于MLC方法,SAM方法对中度退化草甸区分能力最高,对其他退化程度草甸区分能力稍弱。     

New Book

Practical Handbook of Photovoltaics: Fundamentals and Applications.by Tom Markvart and Luis Castañer.     

虚拟结点法在多出口疏散方案中的适用性分析

城市化进程的迅速推进促使城市规模日益扩大、人口密度不断提高,制定一个有效的应急疏散方案,使得人员在存在危险时快速且有序地撤离到安全场所,已经成为迫切需要解决的问题。目前已有一些研究成果,而虚拟结点法在网络流中已有较多应用。结合基于道路网络的单出口分阶段疏散算法,将虚拟结点法应用在多出口疏散方案中,旨在对虚拟结点法的适用性进行分析。模拟结果显示,该方法能够有序、快速地组织大规模人群到安全场所。     

Built environment and social well-being: How does urban form affect social life and personal relationships?

Personal relationships are among the most influential factors for achieving a happy life. Yet, there is insufficient empirical evidence on the role of the built environment in social life and personal relationships. This paper investigates how the urban form affects social life and personal relationships by applying structural equation models to survey data collected in Oslo metropolitan area. Results indicate that residents of compact neighborhoods are significantly more satisfied with their personal relationships compared with residents of low-density suburban neighborhoods. Shorter distances to the city center, higher densities, and mixed land uses are found to positively contribute to overall social well-being. Path analysis as well as qualitative analysis suggest that compact urban forms enable residents to maintain larger networks of close relationships, socialize more frequently with friends and family, receive stronger social support, and enjoy increased opportunities to make new acquaintances.     

Disentangling the effects of the built environment on car ownership: A multi-level analysis of Chinese cities

Reducing the reliance on car-based transportation is a common goal of academics and policy makers, one element of which is car-ownership. This paper contributes to our understanding of the links between socio-economic attributes, the built environment and car ownership. Based on a sample of 3480 individuals across China in 2012, this study examines the impacts of the built environment at both neighborhood and city levels on car ownership and its moderating effects on household income. The results indicate that built environment elements at both levels affect car ownership significantly, and while some elements mitigate the effects of household income on car ownership, others strengthen them. Thus, urban transportation policy should focus on the built environment at both the neighborhood and city levels and promote compact development for the sake of restraining car ownership and encouraging more sustainable modes of travel. Moreover, policy should not ignore the interaction effects between individual socio-economic attributes and the built environment, as their directions are heterogeneous.     

San Francisco's neighborhoods and auto dependency

Suburbanization and auto dependency have major problems. An alternative, the walkable neighborhood system, is one of a number of ideas designed to increase walking and other non-auto modes (NAM), sustainability, economic productivity, physical health, and livability. NAM includes walk, bicycle, public transit, and public cars (taxi, ehail ride, car share, car rental). A walkable neighborhood system has a high population density and complementary features that support local business and transit within an attractive walking distance.For a case study, we look at San Francisco, a world class city with high densities comparable to European cities. This article for the first time delineates neighborhoods in terms of walkable areas and correlations with four indicators of sustainability. We delineated 85 walking-area neighborhoods using ArcMAP and analyzed their correlations with NAM, vehicle miles traveled, walk score, and food sources. The hypothesis of a very high correlation of density and NAM is confirmed: densities over 50 persons per neighborhood acre support NAM above 60%. An exponential decrease in auto dependency with density is confirmed, but with a low correlation. The transition is gradual and uneven among neighborhoods. The large variation of performance among neighborhoods with very similar densities needs more research into complementary features. The correlation of density with vehicle miles traveled is very high, −0.807. The correlation of density with Walk Score is moderate, due to Walk Score being concerned with walkability and not with the underlying land uses supporting sustainability. The correlation of density with food sources is very high and the highest of the correlations we found.     

Children's education or parents' employment: How do people choose their place of residence in Beijing

Residential mobility has become an increasingly important issue in China, where urban families participate frenetically in the commodity housing market leading to soaring property prices. Applying place dependence approach and logistic regression models, this paper examines the association between residential mobility intentions and place dependence for employment and education in Beijing. The results reveal that people's intentions to move homes are driven by place dependence on the access to high-quality schools for their children, while the dependence for employment is rather weak. The findings indicate children's education has emerged as a new driving force that shapes urban space in contemporary China and therefore should be a focal point for planners and policy makers in urban resource distribution. This paper provides evidences to further our understanding of the high premium of properties that enable access to good schools. The needs for other spatial utilities and sentimental attachment to a place also encourage residential mobility intentions, which deserves further research.     

A grey fuzzy multiobjective programming approach for the optimal planning of a reservoir watershed. Part B: Application

The conflict between environmental protection of reservoir water quality and economic development by different uses of land within a watershed is a problem that constantly bothers the public officials in regional planning. Besides, the uncertainties regarding to the fuzzy goals in decision making and the impreciseness of parameter values always create additional difficulties in systems analysis. This paper applies the grey fuzzy multiobjective linear programming (GFMOLP) method for the evaluation of sustainable management strategies for optimal land development in a reservoir watershed. In particular, it demonstrates how uncertain messages in water resources management systems can be quantified by specific fuzzy membership functions and grey numbers in a multiobjective analytical framework. A case study of the planning for land-use programs in the Tweng-Wen reservoir watershed in Taiwan was prepared for the purpose of demonstration.