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1.
In recent years, a significant feature of population change in North American metropolitan areas has been the rapid suburbanization of elderly people. The ability to engage in routine activity may be a necessary condition for the maintenance of independent life styles and psychological well‐being among older suburbanites. Using a conceptual framework based on Parmelee and Lawton's ecological model of aging, this article offers an exploratory investigation of the determinants of the travel of separate samples of elderly male and female suburbanites to each of five destination categories of key service/activity sites in a Canadian city. The results of the tests of ten multiple regression models disclose that the levels of explanation of trip frequency afforded by “autonomy components” (e.g. health‐related characteristics, living arrangements, and income level) vary according to destination category. However, the explanatory power of “security components” (i.e. variables concerning access to destination categories) is generally low. Overall, the findings of the study provide a basis for developing a deeper understanding of the repetitive travel behavior of elderly suburbanites.  相似文献   

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China has established several free trade zones (FTZs) in recent years, which are becoming new drivers of growth for regional economic development. As the FTZ reform deepens, protecting intellectual property rights and improving application systems have become important for encouraging innovation in FTZs. To understand the knowledge spillover effects in different FTZs, this paper selects indicators at different levels of knowledge evaluation and uses the 2017 data of the provinces and cities where the first three batches of FTZs set up by China are located as samples to perform empirical analysis on knowledge spillover effects with a corrected spatial knowledge spillover model. According to the evaluation, the spatial knowledge spillover effects vary among FTZs—the spatial knowledge spillover effects of economically developed regions are smaller (0.0421), while their spillover effects on other FTZs are bigger (0.0795). In addition, the knowledge spillover effects of adjacent FTZ provinces and cities are significantly greater; the spatial spillover effects of southeastern coastal FTZ provinces and cities are more than those of central and western regions as well as northeastern provinces and cities (0.0795; 0.0533; 0.0672). This study is helpful for governments and policy makers to develop appropriate incentive policies for knowledge innovation targeting the knowledge spillover characteristics of different FTZs.  相似文献   

4.
ABSTRACT This paper examines how the college‐educated population—segmented into selective demographic groups, from young adults to the elderly—differentially values quality‐of‐life (QOL) indicators of metropolitan areas in the United States. Using data from the 2000 Census and the 1997 Places Rated Almanac, out‐migration patterns are shown to depend jointly upon stage in the life course, the spatial‐demographic setting, and QOL characteristics. An abundance of cultural and recreational amenities lowers out‐migration rates of young college‐educated. For the older college‐educated population, the revealed preferences shift toward concerns for safety and a strong preference for milder climates. The study also finds significantly lower out‐migration rates for metropolitan areas with growing human capital. In light of shifting age distributions and rising educational attainment levels, the results have important implications for the emergence of new migration patterns and the concentration of human capital.  相似文献   

5.
Societies in many developed nations around the world are aging. Over the past decade, a growing body of research has emerged internationally in an effort to anticipate and prepare for the transport challenges posed by this unprecedented demographic change. This paper contributes to this line of research by offering new insights into senior travel behavior focusing on the recent Canadian experience. Using weekday data from the 1992 and 2005 General Social Surveys on time use, changes in the number of trips, the duration of trips, trip mode, and trip timing are evaluated for urban seniors. In contrast to the experiences of many other developed nations, analysis of the first three indicators of behavioral change refutes the notion that “automobility” has increased in Canada over the 13‐year period. While this finding is encouraging, it is tempered by the fact that Canadian seniors who choose to travel by car are doing so increasingly during the morning and evening peak periods. The results from a peak versus non‐peak departure‐time model that pools data from both years offer important insights into factors driving this change. For instance, the results suggest that the propensity to start a trip during rush hour has increased over time for non‐work trip purposes.  相似文献   

6.
Trend of aging has raised new requirements for Chinese city transportation system. Based on the sum-up of trip characteristics of elderly people, some adaptability problems of current transportation system were pointed out, concerning accessibility, transit reliability and comfort, walking environment, and barrier -free facility. Then, according to experience of foreign countries, some improvement suggestions were raised here, such as development of transit, construction of barrier - free facility, improvement of walking environment, and traffic safety education.  相似文献   

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"The proportion of a region's population that is elderly may change over time for many different reasons. The proportion may grow because of the net in-migration of elderly individuals, or it may grow because of the net out-migration of nonelderly residents. Furthermore, the proportion may grow if the number of nonmovers in the 'pre-elderly' cohort is relatively high. This paper discusses in detail the ways in which this proportion may change over time. This is complemented by a state-level empirical study of elderly population growth in the United States during the late 1980s. The spatial pattern of the rate of new entry into the elderly cohort among nonmovers is found to be particularly influential in determining changes in the proportion of a state's population that is elderly."  相似文献   

8.
针对汽车尾气排放的非线性、时变性问题,提出一种三维谱特征下的汽车尾气评估方法。该方法利用频谱分析的原理对汽车尾气进行时频转换,得到尾气的三维谱特征。这些三维谱特征作为输入被提交给径向基神经网络,在K均值聚类算法的驱动下,径向基神经网络完成训练与测试,实现对三维谱特征的分类,从而评估相应的汽车尾气排放水平。数值实验结果表明,提出的汽车尾气评估方法具有较高的准确性。  相似文献   

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The Historic Conservation District(HCD) is an important target for urban heritage protection in China. The spatial characteristics of its road system,formed before the appearance of automobile,do not adapt to the car traffic. In the context of very rapid motorization in Chinese cities,the increase in car traffic brings an inevitable trouble for the protection of HCDs. Road widening and pedestrianization are two popular solutions to this problem in current practices; however,both of them may lead to negative consequences. Inspired by the development of Zone 30 in European cities,this paper firstly cleared up first some misunderstandings of the concept of traffic calming,then taking the inner city of Paris as an example,explained how traffic calming measures can be implemented in HCDs and what effects will be generated. Finally,it discussed the possible application of traffic calming measures in HCDs projects in China and pointed out the specific situations of Chinese cities to which the planners should pay more attention.  相似文献   

10.
ABSTRACT In the U.S., people are more likely to be poor if they live in a nonmetropolitan (nonmetro) than in a metropolitan (metro) area. A common explanation for this phenomenon is that nonmetro places offer relatively few economic and social opportunities. This article explores another plausible explanation, asking if the disproportionate poverty in nonmetro areas partly reflects attitudes of people with personal attributes related to poverty: they may be attracted to nonmetro places or otherwise reluctant (or unable) to leave them. To test this hypothesis, data from nine waves of the Panel Study of Income Dynamics (PSID) are used to track economic well‐being and nonmetro–metro residential choice among a sample of 2,007 low‐income householders. A series of multivariate regression models are estimated in which the dependent variable is a householder's income to need (adjusted for spatial cost‐of‐housing differences), and regressors are individual attributes, a binary variable for nonmetro residence, and state fixed‐effects. Regression results show that controlling for householder educational attainment reduces the negative association between nonmetro residence and income to need; but controlling for unobserved, time‐invariant heterogeneity via individual fixed‐effects increases the magnitude of this negative association. Study findings thus appear to indicate that enduring nonmetro poverty is explained both by a sorting of low human capital individuals into nonmetro areas and by reduced economic opportunities in nonmetro compared to metro places.  相似文献   

11.
Taking the planning of elderly building for example, this paper explored the spatial layout, entrance/exit design, road space design and landscape design of the elderly residential districts against the background of population aging and increasing demands of ecological residence. In addition, the paper tried to fully use outstanding natural environment in mountainous areas to plan the elderly community, and integrate the characteristics of mountainous community planning and elderly buildings.  相似文献   

12.
为研究新乡市日照时数的时空变化特征及影响因子,本研究利用新乡市7 个气象站1966—2016年逐月日照时数、总云量、水汽压、平均风速、降水量和相对湿度资料,采用线性趋势分析、t 检验等方法,结合GIS 技术,分析日照时数的时间变化趋势及空间分布特征,对年日照时数进行突变检验,并分析5个气象要素对日照时数的影响。结果表明:1966—2016 年,新乡市年日照时数呈显著减少趋势,其中夏季日照时数下降最明显,春季下降速率最小,年日照时数在1983年和1999年附近发生突变;日照时数总体呈“中间多南北少”的空间分布特点,且京广线以东地区偏多;年日照时数与总云量、水汽压呈极显著负相关,与平均风速呈极显著正相关,与降水量和相对湿度年的变化无明显相关性。  相似文献   

13.
This paper studies the population growth dynamics in European NUTS3 regions over the period of 2000–2015 and offers generalizable evidence on the main drivers of population change at this sub‐level of analysis, which is so far rather unexplored. Results obtained by means of a spatial Durbin model highlight the roles of economic and demographic regional conditions in shaping population dynamics and the minor role of geography and environmental conditions. The fact that geographical polarization of population is occurring, which might result in an increase in regional imbalances, calls for policy actions in mitigating this phenomenon.  相似文献   

14.
Integrated Pest Management (IPM) aims to promote physical and biological regulation strategies that help farmers contain populations of pests (pathogens, animal pests and weeds) and to finally reduce the reliance on pesticides. It is based on the holistic combination of multiple management measures rather than on the sum of single methods, each of them having only small effects on pests reduction. Thus, to analyse the interactions between IPM measures and to evaluate the sustainability of their implementation, we require an approach considering the whole cropping system (CS), i.e. a functional entity whose complexity is more than the sum of its parts. A network of European experiments at the CS level was set up recently, and aimed at sharing data and expertise to enhance knowledge of IPM. Comparison of existing methodologies highlighted a diversity of CS designs and experimental layouts. We deduced that the concept of CS itself was viewed differently among scientists, and this affected experimental protocols. Other differences were related to the research context and objectives. Some experiments aimed to explore very innovative strategies and generated knowledge on both their effects on the agroecosystem and their ability to satisfy a set of performance targets, while others aimed to provide quickly adoptable solutions for local farmers in line with the current socio-economic constraints. In some research programmes, the experiment was part of the CS design process — and tested CS were regularly revised based on an continuous improvement loop — while in other cases CS were kept stable across years so as to enable the evaluation of their long-term cumulative effects. A critical aspect contributing to the diversity among CS experiments was the distinction between a factorial design of experimental CS and systemic approaches: factorial experiments allowed quantification of the effects of each IPM component regardless of the consistency between components defining the CS. In contrast, systemic approaches focused on the overall evaluation of CS designed with consideration of their consistency, hence maximising their ability to meet the objectives. Because CS experiments represent a huge investment in terms of economics and time, preliminary reflections of the relevance of the experimental strategy is of critical importance.  相似文献   

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Industrial poverty alleviation is one of the most important aspects of targeted poverty alleviation. Identifying the mechanism influencing the spatial differentiation of the benefits of industrial poverty alleviation plays an essential role in optimising an industrial layout for poverty alleviation, consolidating poverty alleviation achievements, and revitalising rural industries. This study examined the spatial distribution characteristics and influencing factors of the benefits of industrial poverty alleviation at the village level using the household data collected from Jiangjin District, Chongqing, China. The results show that the benefits of industrial poverty alleviation presented obvious spatial differentiation in the villages with the overall performance being high in the north and low in the south and decreasing from the south of the county to the north and south. Spatially, there was a significant positively correlated agglomeration effect. High-value agglomeration areas were concentrated in the north with the characteristics of ‘one centre and two subcentres’. However, low-value and outlier agglomeration effects were not obvious, presenting sporadic distribution. Seven major factors affect industrial poverty alleviation in Jiangjin District, including average altitude and land transfer rate. The interaction between any two of the seven factors has a more significant impact than that of a single factor.  相似文献   

17.
While internal migration in contemporary China ascribes a great change to urban China's demographic composition, social structures and economic development trajectories, it is yet to restructure the formal definitions of urban identity and belonging, which are still dominated by the household registration system (hukou). The paper suggests that as a result of changes in the political, economic, demographic and social contexts within which China's internal migration develops, there emerge a crucial need to re‐examine the crude forms of determining identity and belonging, questioning the addressing of spatiality within the existing mechanisms (such as hukou system or the shiminhua discourse). To do so, the paper argues that the existing de‐territorialisation of the migration experience has to be replaced with a more nuanced understanding of how spatial practices and conceptualisations shape migrants’ experiences, as it is becoming imperative to develop a new framework that is more sensitive to migrants’ lived process of identification and belonging, especially as these traverse multiple geographies and spatial scales. This close engagement with migrants’ spatiality can then be used as a base from which to engage with a more complex view of migrants’ spatial and social relatedness, as well as the development of their urban belonging and identity.  相似文献   

18.
为明确湘西烟叶的口感特性评价指标的区域特征和空间分布特征,对来自湘西烟区的41个烟叶样品进行感官评价。结果表明:(1)湘西烟叶刺激性有至稍有;干燥感多数表现为有,少数稍有;余味以尚净尚舒适为主。(2)烟叶刺激性、干燥感县域间差异不显著;余味差异极显著,主要是古丈县烟叶的余味标度值极显著高于其他各县。(3)不同乡镇之间以红石林镇的余味标度值最高和干燥感标度值最低;高坪乡、列夕乡的刺激性标度值最低。(4)‘K326’的口感特性较‘云烟87’要好。(5)海拔低于600 m烟区的烟叶口感特性较其他海拔好。(6)烟叶刺激性、干燥感、余味在空间上分别以标度值2.6~2.8、2.7~2.8、2.6~2.8分为主要分布;口感特性评价指标标度值呈斑块状分布态势。  相似文献   

19.
Total reliance on herbicides for weed control is unsustainable with the spread of herbicide resistance and the environmental need to reduce pesticide use. Strongly competitive wheat crops that have high tolerance to weed pressure and therefore maintain high yields in the presence of weeds are a low-cost option for reducing dependence on herbicides. We examined the feasibility of selecting for wheat tolerance to weeds by crossing varieties differing for traits associated with competitiveness. Competitive ability and yield potential must be treated as separate traits for selection. Current measures of crop tolerance to weed competition do not separate the two traits so that selection based on these measures is often synonymous with selection for yield potential rather than pure tolerance. We propose a new measure, termed Incremental Crop Tolerance (ICT) that reflects the incremental yield difference between genotypes associated with tolerance, over and above differences in underlying yield potential.  相似文献   

20.
Using hedonic models, we analyze the effects of proximity and noise on housing prices in neighborhoods near Hartsfield‐Jackson Atlanta International Airport during 1995–2002. Proximity to the airport is related positively to housing prices. We address complications caused by changes over time in the levels and geographic distribution of noise and by the fact that noise contours are measured infrequently. A general decline in noise boosted housing prices during 1995–2002. After accounting for proximity, house characteristics, and demographic variables, houses in noisier areas sold for less than houses subjected to less noise. Also, the noise discount is larger during 2000–2002 than 1995–1999.  相似文献   

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