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1.

The effect of distance upon agricultural production should be as apparent among primitive subsistence agriculturalists as in market-oriented societies. This analysis of yield variations among the Basotho of southern Africa attempts to determine the frictional effect of distance. The results show that distance does not explain variations in yield even when other physical factors are held constant. Perhaps such variables as household characteristics, not included in the analysis, would provide a better explanation.  相似文献   

2.
《Urban geography》2013,34(5):450-468
Residential rent shift variations across space are essential components of urban dynamics. For example, they play an important role in the context of housing availability, housing affordability, and urban revitalization. This paper develops a rent shift model that includes spatial variables and traditional housing market attributes such as housing quality and resident composition. The model estimation employs data for the City of Chicago, 1970- 1980. The results show that the impact of housing market attributes on rent shifts are distorted if spatial effects are neglected. They further support the hypothesis that spatial rent shift regularities prevail after controlling for variations in housing market attributes. Specifically, rent shifts decrease in a nonlinear fashion with increasing distance from the Central Business District (CBD). The distance relationship varies as the orientation toward the CBD changes. In addition, the positive effects of spatial lag variables are highly significant and suggest a rent equilibrating mechanism operating across urban space.  相似文献   

3.
哈尔滨市城乡结合部不透水面时空变化及驱动力分析   总被引:4,自引:1,他引:3  
李苗  臧淑英  吴长山  田旸 《地理学报》2017,72(1):105-115
本文选取哈尔滨市城乡结合部为研究区,以1984年、1993年、2002年和2010年的TM影像数据为数据源,利用混合像元分解方法提取了哈尔滨市城乡结合部的不透水面信息。分析了不透水面的时空变化特征。选取坡度、坡向、DEM、距河流距离、距高速公路距离、距铁路距离、距主要路距离和距1984年城区距离8个因子,利用增强回归树法进一步分析了1984-2010年哈尔滨市城乡结合部不透水面扩张的主要影响因素。结果表明:1984年哈尔滨市城乡结合部不透水面所占比例为3.9%、1993年为6.6%、2002年为9.0%、2010年为16.52%。高速公路、铁路、主要路等交通要素带动周边地区的发展,从而导致道路沿线城市扩张速度较快。  相似文献   

4.
Rice is the main food crop in densely populated Bangladesh. Regional climatic variations can play an important role in rice productivity. For example, excessive heat or extremely cool conditions disrupt normal plant physiological processes and cause plant injury which, in turn, results in reduction of yield. In this study, the climatic crop productivity model YIELD has been applied to calculate rice productivity for the boro rice growing season (December/January-May) in Bangladesh under changing climatic conditions. The model estimates climatic influences on various rice plant-growth parameters. YIELD was tuned and validated to Bangladesh's environment to represent appropriate agroecological conditions. The model was run using long-term average climate data of 12 meteorological stations located in the major rice-growing regions in Bangladesh to establish baseline estimates of yield. For the climate change study, 20 scenarios were created by synthetically fluctuating thermal and solar climates in Bangladesh. Study results show that per 1° C increase in growing season mean air temperature, boro rice yield was reduced by 4.6%. It was also found that each 10% increase in incident solar radiation resulted in a 6.5% increase of boro rice yield in Bangladesh.  相似文献   

5.
Out-migration from rural areas and generational shifts create conditions whereby increasing numbers of private forest owners live at a distance from their forestland. Geographical distance and non-residency have been raised as issues that may possibly weaken these owners’ relationships with their properties. Drawing on the “sense of place” concept as a frame of analysis for 51 qualitative interviews with resident and nonresident private forest owners from two areas in Sweden, this study provides in-depth understanding of how geographical distance and place of residency shape owners’ feelings about their forest properties. The study shows that sense of place is constructed in complex and multifaceted ways over time and that social and historical contexts and processes beyond the forest environment can make owners feel closeness to their distant properties. Thus, geographical distance or residency alone does not explain variations in these forest owners’ feelings of distance or closeness to their properties.  相似文献   

6.
7.
One of the primary goals of coastal water quality monitoring is to characterize spatial variation. Generally, this monitoring takes place at a limited number of fixed sampling points. The alternative sampling methodology explored in this paper involves high-density sampling from an on-board flow-through water analysis system (Dataflow). Dataflow (West Palm Beach, FL, USA) has the potential to provide better spatial resolution of water quality features because it generates many closely spaced (<10 m) measurements. Regardless of the measurement technique, parameter values at unsampled locations must be interpolated from nearby measurement points in order to generate a comprehensive picture of spatial variations. Standard Euclidean interpolations in coastal settings tend to yield inaccurate results because they extend through barriers in the landscape such as peninsulas, islands, and submerged banks. We recently developed a method for non-Euclidean interpolation by inverse path distance weighting (IPDW) in order to account for these barriers. The algorithms were implemented as part of an R package and made available from R repositories. The combination of IPDW with Dataflow provided more accurate estimates of salinity patterning relative to Euclidean inverse distance weighting (IDW). IPDW was notably more accurate than IDW in the presence of intense spatial gradients.  相似文献   

8.
刘春芳  王川  刘立程 《地理研究》2018,37(2):419-432
以地处三大自然区过渡地带的榆中县为案例,分析了1995-2015年县域及内部分区生境质量演变的时空特征,借助地理探测器模型分析并探索了生境质量影响因素及其机制。结果表明:① 全县生境质量变化保持稳定并略有提升,县域内部生境质量变化呈现出由南向北递减的三级梯度特征;② 全县生境质量的地带间与地带内差异均趋于缩小,北部黄土高原区持续加大,中部平原区连续下降,南部山区则先缩小后增大;③ 全县及县域内部的影响因素及机制因为地理尺度的差异而不同。自然环境变量对生境质量变化发挥着基础和关键性的作用,社会经济变量呈现出减小的态势,而政策调控变量对生境质量的影响则越来越大,各因子间的协同增强效应推动了生境质量的变化。  相似文献   

9.
Two groups of subjects with varying amounts of experience with the city in which they lived judged from memory distances between familiar locations. The distance judgments were processed by a multidimensional scaling algorithm (MULTISCALE) that estimates the parameters of a power function transformation of the response scale and the coordinates of the locations in k-dimensional euclidean space. The results for both subject groups suggested that inaccuracies of distance cognition do not reflect the noneuclidean nature of urban cognitive maps but are caused by response bias.  相似文献   

10.
《Urban geography》2013,34(2):142-163
This article reports an empirical analysis of the shopping center cognitions of subgroups of older urban consumers domiciled in (a) the central area and (b) two contrasting suburban distr' ts. Attention is focused on two behavioral constructs which underlie consumer spatial dec'sion-making: f (i) information field, and (ii) evaluative criteria. The data are based on a questionnairehterview survey of ambulatory elderly residents of Winnipeg, Manitoba. The findings disclose significant differences among the subgroups concerning both the magnitudes and compositions of their information fields. Additionally, the results of a resistanceto- change experiment reveal that each subgroup identifies "distance from home," "prices," and provision of a "grocery supermarket" as the most important of seventeen shopping center attributes. Significant differences among the levels of importance assigned to eight of the other attributes not only reflect the limited mobility of the central area elderly, but also the contextual effects of the local shopping resources of the three subgroups.  相似文献   

11.
12.
Many of the techniques used to describe the location of human activities incorporate physical definitions of distance and area, although other definitions are methodologically preferable. Using Boone County, Missouri as an example, the physical-distance regularity of city spacing is described by the nearest-neighbor statistic, modified to compensate for boundary effect. The statistic is reformulated with an estimate of temporal area, defined by analogy with shape-compactness measures, and travel times. Application of the refined formula reveals greater regularity of city spacing in functional space than in physical space.  相似文献   

13.
The paper summarizes two decades of fitting existing techniques and developing new spatial methods in order to aid the cloud seeders in proving or disproving the value of deliberate rainfall augmentation in Israel. While the spatial regression and the distance correlation matrix (DISTCORMAT) techniques served to distinguish between deliberate rainfall enhancement and inadvertent urban climate modification, the composite correlation map revealed an increase of rainfall duration and an extension of the rainfall target area. Hydrological parameters were utilized to assess the effect of cloud seeding on water resources. Indirectly, the hydrological evidence supported the positive effect of the cloud seeding. Those findings also suggest that cloud seeding augments the rainfall intensity, but interpretation of the composite correlation map does not support this notion. [Key words: cloud seeding, spatial analysis techniques, DISTCORMAT technique, composite correlation map, multiple regression analysis, hydrological parameters, Israel.]  相似文献   

14.
宗跃光 《地理研究》1998,17(2):119-124
由于存在城市中心梯度场和廊道效应梯度场,在单纯经济利益趋动下,城市本质上存在摊大饼倾向,这将严重破坏城市合理景观结构与生态平衡.文中运用廊道效应原理,研究人工廊道与自然廊道相互作用过程,结合北京中心市区不同时期空间扩展格局,分析城市景观8个方位廊道的扩展量、扩展速度及变化趋势,提出将自然廊道体系纳入北京大都市区规划,形成人工廊道与自然廊道相间分布的星状分散集团式景观格局,以有效阻止建成区摊大饼过程.  相似文献   

15.
王庆喜  胡志学 《地理科学》2018,38(11):1828-1836
利用2005年中国规模以上制造业企业数据,以长三角地区为范围,对企业地址进行地理编码,建立企业点对点的空间邻近关系,将距离从5 km逐次扩大到100 km,进行企业知识溢出的空间效应分析。研究发现,长三角地区的研发企业比较集中,大约在20 km范围内有明显的集聚状况,之后则有比较明显的分散,并与整体制造业活动空间分布趋向一致。知识溢出的空间强度随距离递增呈负指数幂函数形式加速衰减,于40 km处左右减势趋于平缓。与连续空间上的微观数据分析相比,区域层面上的归并数据分析放大了知识溢出的效应。  相似文献   

16.
厦门城市自助游网络结构及机制研究   总被引:1,自引:1,他引:0  
从省外自助游客发表在携程网上的厦门游记中提取旅游流信息,运用社会网络分析和QAP相关分析对城市自助游网络结构特征及形成机制进行研究。结果表明:在时间、经济等多重制约因素的影响下,厦门旅游节点呈现高度的不均衡性,处于核心区域的7个节点间彼此联系密切,且节点间的距离较近,形成高度集聚效应,对省外自助游客形成了“刚性”吸引力,其他边缘区旅游产品是第二选择;边缘区节点“抱团”现象也很普遍,无论是节点较为密集的环岛路还是岛外的节点群,说明即便在交通体系已经很发达的厦门,距离摩擦对于游客游览路线的选择均起到一定影响;QAP相关分析得出旅游流的形成与距离对外交通设施和酒店的远近相关性不显著,与节点的公共交通通达性、网络知名度及节点的集聚程度有显著的相关性;针对岛内外节点应采取不同的策略来降低时间和经济成本,提高核心节点游览效率,完善预警机制,同时挖掘岛内外旅游产品的互补性,从而实现旅游空间的相对均衡。  相似文献   

17.
A method is presented by which it is possible to estimate the initial rate of chemical reactions when theexperimental conditions are varied according to a response surface design.The method is intended as acomplementary method for analysing data obtained from experiments in synthetic chemistry when theobjective is to optimize the yield of the reaction.Data obtained by simulations have been used to develop the method.From the simulated reactions itis shown that sequential analysis of the chemical yield of the reaction makes it possible to estimate modelswhich describe how the parameters of the response surface of the yield vary over time.The derivativesof these time functions of the response surface parameters can be used to define a rate function whichdescribes how the variations in the experimental conditions influence the rate of the reaction.It is shown how such rate functions can be used to afford reasonable estimates of the initial rates ofthe reaction.The initial reaction rates thus estimated can be used to determine the kinetic order of thereactants and also to provide estimates of the activation energy of the reaction.A thorough discussion of how canonical analysis of the rate function may assist in the elucidation ofreaction mechanisms is given.  相似文献   

18.
昆明大气降水稳定同位素分析   总被引:3,自引:0,他引:3  
为阐明昆明地区稳定同位素与大气降水的关系,对GNIP昆明站点1986~2003年δD和δ18O进行分析,初步建立当地大气降水线方程,并与中国及全球降水线方程进行对比,揭示该降水线方程的特征.研究结果表明:大气降水稳定同位素组成受到温度、蒸发、水汽源地等多种因素的复杂影响,在不同时间有很大差异.研究区大气降水稳定同位素存在明显的季节变化,雨季偏负,旱季偏重,降雨效应明显,并在很大程度上影响和掩盖了温度效应.而d受其特殊地理位置影响,呈现出雨季高旱季低的独特变化特征.  相似文献   

19.
To evaluate the effect of sample preparation on the trace element composition of ostracod shells, fossil shells subjected to various cleaning steps were analyzed by ICP-AES. The variations in ostracod Mg/Ca ratios reveal that fossil ostracod samples cleaned by ultrasonic methanol yield lower values than those by other methods, including increasingly rigorous reductive cleaning. In our sample sets, shell Mg/Ca decreases ∼ ∼1.5 mmol/mol during clay removal. Sample Sr/Ca results do not seem to vary significantly under the equivalent cleaning steps. For ostracod analysis, pre-treatment using multiple methanol ultrasonic cleaning is suggested to be used for gaining an appropriate result.  相似文献   

20.
加拿大爱得蒙顿市犯罪问题的地理研究*   总被引:4,自引:0,他引:4  
杜德斌 《地理研究》1998,17(4):415-422
运用GIS技术和回归分析方法,分析加拿大爱得蒙顿市各类犯罪的空间分布规律。结果发现:城市犯罪分布的空间差异异常明显,城市内部存在少数极端的犯罪高发区;犯罪的空间分布遵循距离衰减规律,表现为距城市中心越近的地区犯罪发生密度越高,距城市中心越远的地区犯罪密度越低;犯罪发生密度与居住人口密度成正相关,即居住人口密度越高,越容易诱发犯罪,但不同类型的犯罪与居住人口密度的关联程度不一样;不同用地性质的区域犯罪发生密度存在明显差异,在各类用地中,商业区为城市犯罪的高发区。  相似文献   

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