共查询到20条相似文献，搜索用时 15 毫秒
1.
The Internet, mobile phone and space-time constraints 总被引：2，自引：0，他引：2
While the implications of information and communication technologies (ICTs) for daily travel and activities have been studied extensively, there is only scant attention paid to the relations between ICTs and space-time constraints. This study therefore explores the extent to which the Internet and mobile phone increase the spatial and temporal flexibility of everyday activities through a review of the literature and empirical research with data from Columbus (Ohio, USA) and Utrecht (The Netherlands). The analysis suggests that the implications of the Internet and mobile phone are complex and dependent on the type of activity, persons involved, technologies and socio-physical context in which they are embedded. Various regularities can, however, be detected. For the study participants, the Internet and mobile phone relax temporal constraints to a stronger degree than they enhance spatial flexibility. There are also space-time constraints that seem to persist or have come about because of ICT adoption. Finally, it appears that the Internet and mobile phone at best consolidate differences between men and women in the space-time constraints associated with everyday activities. 相似文献
2.
The territorial dimension of the digital divide is usually considered as a phenomenon that penalizes the peripheral regions,
especially in terms of regional economic development. Taking into account the territorial networking of ICT (Information &
Communication Technologies) infrastructures—particularly high-speed networks—provides what is probably the principal reason
for such a perception. This is particularly true considering that the most-peripheral regions and those with the smallest
population densities are also the poorest in terms of ICT infrastructures. In Western countries, however, the digital divide
is no longer the result of network-related problems. Nowadays, the issue of the skills required to adequately exploit the
potential of ICT is at the forefront. Yet this evolution is likely to lead to an inversion of the inequalities between the
centre and the periphery, as populations without such skills—recent immigrants, the unemployed, the illiterate, people with
little education or on low incomes and other socially marginalized people—are generally concentrated in urban centres. Consequently,
the priority for reducing inequalities of access to ICT resources is no longer the provision of high-performance ICT infrastructures
for peripheral regions, but rather the implementation of continuing education and social action policies within the urban
centres. 相似文献
3.
4.
基于微博平台的中国城市网络信息不对称关系研究 总被引：3，自引：0，他引：3
网络信息空间的空间关系及信息流研究为信息化影响下的地理空间演变研究奠定基础。借助微博这一新兴网络信息传播平台获取中国城市间网络信息联系数据,采用流分析方法呈现城市间网络信息联系的空间格局。研究发现:中国城市网络信息关系呈现出"一超多强"的空间极化不对称格局。网络空间不对称格局与地理距离、经济社会发展水平存在密切关联性,表现为:城市对外网络信息总不对称度与其经济社会发展水平的相对一致性;经济社会发展差距对城市间网络信息不对称程度影响的距离衰减性;城市间网络信息不对称程度与经济社会发展差距的相对一致性;东、中、西部三大地区间网络信息不对称关系与经济发展梯度的相对一致性。 相似文献
5.
Shawn Van Ausdal 《Geoforum》2009,40(5):707-719
This article examines the expansion of cattle ranching from 1850 to 1950 into lowland forests of Colombia. Although most attention to ranching as a source of deforestation in Latin America has focused on the second half of the 20th century, in Colombia it has a much longer history. The article also examines the role of introduced African grasses in the process of pasture development. While it discusses their ability to suppress secondary-forest regeneration, it underscores their contribution to productivity gains to help explain their wide diffusion. Lastly, the article suggests that paying greater attention to the costs and labor of pasture formation can serve as a springboard to reexamine a number of common stereotypes about ranching: that the logic of livestock was not about producing beef; that cattle were primarily a means to control territory; and that ranching ‘profits’ stemmed from extra-economic sources. Although there is some truth to these explanations, the dominance of cattle throughout the countryside cannot be explained without taking the economic and productive logic of ranching into account. This, in turn, should also help push us to better understand the nature of landed power and the dynamics of agrarian change in Colombia. 相似文献
6.
Large ore-placer districts in the southern and eastern framing of the North Asian Craton (Bodaibo, Upper Selemdzha, South Verkhoyansk, and Ten’ka) are characterized by some common features such as the confinement to the areas of the decreased crustal thickness and gravity gradient zones traced by deep-seated faults; the fold-thrust structure of the terrigenous-black-shale sequences; the phyllitic, greenschist, and sometimes epidote-amphibolite metamorphism of the ore-bearing rocks; and the complex and long history of the Au accumulation, which involved the subsequent stepwise change from the ore-preparatory to the ore-generating stages. The latter stage is spatially and temporally related with manifestations of orogenic (volcanoplutonic) magmatism, which produced mineralization of the gold-quartz, gold-sulfidequartz, gold-black shale, gold-rare metal, and gold-silver formations. The peculiarities of their spatial relations (juxtaposition-superposition or lateral zoning) determine the scales of the noble metal concentration, the economic significance of the deposits, and the metallogenic potential of the regions. The revealed similarity in the evolution and structure of the compared districts should be taken into account in choosing new promising areas and estimating the potential gold-bearing territories in the framing of the North-Asian and other cratons. 相似文献
7.
8.
For mineral resource assessment, techniques based on fuzzy logic are attractive because they are capable of incorporating uncertainty associated with measured variables and can also quantify the uncertainty of the estimated grade, tonnage etc. The fuzzy grade estimation model is independent of the distribution of data, avoiding assumptions and constraints made during advanced geostatistical simulation, e.g., the turning bands method. Initially, fuzzy modelling classifies the data using all the component variables in the data set. We adopt a novel approach by taking into account the spatial irregularity of mineralisation patterns using the Gustafson–Kessel classification algorithm. The uncertainty at the point of estimation was derived through antecedent memberships in the input space (i.e., spatial coordinates) and transformed onto the output space (i.e., grades) through consequent membership at the point of estimation. Rather than probabilistic confidence intervals, this uncertainty was expressed in terms of fuzzy memberships, which indicated the occurrence of mixtures of different mineralogical phases at the point of estimation. Data from different sources (other than grades) could also be utilised during estimation. Application of the proposed technique on a real data set gave results that were comparable to those obtained from a turning bands simulation. 相似文献
9.
C. M. Knox-Robinson 《Australian Journal of Earth Sciences》2013,60(5):929-941
Modern exploration is a multidisciplinary task requiring the simultaneous consideration of multiple disparate geological, geochemical and geophysical datasets. Over the past decade, several research groups have investigated the role of Geographic Information Systems as a tool to analyse these data. From this research, a number of techniques has been developed that allow the extraction of exploration‐relevant spatial factors from the datasets. The spatial factors are ultimately condensed into a single prospectivity map. Most techniques used to construct prospectivity maps tend to agree, in general, as to which areas have the lowest and highest prospectivities, but disagree for regions of intermediate prospectivity. In such areas, the prospectivity map requires detailed interpretation, and the end‐user must normally resort to analysis of the original datasets to determine which conjunction of factors results in each intermediate prospectivity value. To reduce this burden, a new technique, based on fuzzy logic principles, has been developed for the integration of spatial data. Called vectorial fuzzy logic, it differs from existing methods in that it displays prospectivity as a continuous surface and allows a measure of confidence to be incorporated. With this technique, two maps are produced: one displays the calculated prospectivity and the other shows the similarity of input values (or confidence). The two datasets can be viewed simultaneously as a three‐dimensional perspective image in which colour represents prospectivity and topography represents confidence. With the vectorial fuzzy logic method, factors such as null data and incomplete knowledge can also be incorporated into the prospectivity analysis. 相似文献
10.
Urban experience takes an informational turn: mobile internet usage and the unevenness of geosocial activity 总被引：1，自引：0，他引：1
Matthew James Kelley 《GeoJournal》2014,79(1):15-29
Coinciding the widespread deployment of handheld information and communications technologies (ICT) there has been a rapid emergence of mobile Internet applications. Notably, these applications are designed to perform within operating systems that are not only Internet-connected but that are also location-aware and decoupled from any single point in space—design characteristics that enable instantaneous integration of users’ everyday ‘real-world’ experience with an array of Internet-based services. As a consequence, the experience of urban space can be mediated by digital information in ways that have not before been possible. In this article I explore the convergence of ongoing discussions about the digital divide, the nascent class of mobile ICT, and the urban communities that have been most adversely impacted by uneven technological landscapes. Building on this convergence, I argue that it is increasingly important to consider the impacts that pervasive mobile information have on the composition of everyday urban life. 相似文献
11.
This paper is devoted to describe a new method of fuzzy logic applied to multi geohazards macro-zone maps. The basic steps are (1) compilation of macro-zone maps for each type of geohazard phenomenon. Each phenomenon is then assigned one of seven geohazard zones: very low, low, relatively low, moderate, relatively high, high, and very high; (2) definition of a membership function using a fuzzy logic algorithm to quantify the qualitative data, estimate a geohazard grade for each mesh point, and to convert qualitative maps to quantitative maps; (3) computation of the summed hazard grade for each mesh point and creation a cumulative geohazard map; and (4) compilation of a multi geohazards macro-zone map by defining a mathematical algorithm and again using fuzzy logic. The paper also describes a mechanism that takes subjective engineering judgments into account. Finally, a geohazard map with a scale of 1:25,000 (Rahdar district, Khuzestan, Iran) is compiled. This study divides the area into seven geohazard macro-zones. Zones of high and very high geohazard classification cover most of the area due to the large number of sinkholes and asymmetric subsidences, rock falls and other slop movements. Low and very low hazard zones only cover small localities. 相似文献
12.
基于GIS的网络电子地图系统开发与研究 总被引：3，自引：0，他引：3
随着Internet技术的发展和人们对地理信息系统（GIS）的需求,网络上空间数据的发布,已经成为GIS的发展趋势。网络电子地图随之应运而生。我们以ArcIMs9．0作为webMap服务器,MicrosoftⅡS作Web）服务平台,结合javaScript,XML对网络电子地图系统的开发进行了探讨和研究,以合肥工业大学校园为背景,完成了的网络电子地图的系统模型构架。系统的查询、浏览、空间分析等功能齐全,使用方便。系统模型可在相关地区移植,利于推广,避免重复开发。 相似文献
13.
Network configurations and R&D activities of the ICT industry in Suzhou municipality, China 总被引：3，自引：0，他引：3
This paper analyzes the network structure and R&D activities of the information and communication technology (ICT) industry in Suzhou municipality, known previously for its local state-directed Sunan model of development. Suzhou, however, has been undergoing dramatic restructuring to remake itself into a globalizing production center. We highlight the significance of the Chinese state and local/regional assets in shaping the trajectories of globalization and regional development, and the increasing importance of domestic markets and regional clusters/agglomeration for foreign ventures. We have found that Suzhou’s development path, heavily dependent on external forces, has made Suzhou a TNC (transnational corporation) satellite district. We also find that the ICT industry in Suzhou has a dual-structure, segmented between foreign-invested enterprises (FIEs) and domestic firms. TNCs tend to network among themselves and their interfirm networks are increasingly domestic and regionally embedded in the Yangtze River Delta, while the linkages between TNCs and local firms are weak. We argue that there is a series of technological, structural, spatial, and institutional “mismatches” that limits the establishment of “global pipelines” of knowledge exchange. We hold that the nature of global-local networks is contingent upon regional endogenous capacities and the specific ways in which global capital interacts with local institutions. Therefore, perspectives on TNCs’ local embeddedness must be positioned in their regional/external networks. We also analyze the constraints placed on Suzhou’s development into an innovative city and promote the integration of global and local/regional assets through development of indigenous capacities. 相似文献
14.
Land reclamation in Singapore,Hong Kong and Macau 总被引：2，自引：0，他引：2
The spatial and temporal significance of land reclamation from the sea in relation to the development of the three SE Asian small coastal territories of Singapore, Hong Kong and Macau are examined and compared. In all three territories the rate of reclamation has been an index of the rate of economic development. Four phases of land reclamation are identified: (1) pre-1900: involved relatively unplanned and uncostly projects in shallow water and swamplands around the main focus of settlement; (2) 1900–1945: involved military projects outside the main settlement core; (3) 1945–1980: this phase of large-scale projects unconstrained by natural conditions because of advances in technology and high rate of reclamation was driven by rapid industrial and population growth; (4) 1980 to date: a period marked by large infrastructure projects designed to maintain and extend the status of the territories as world economic and commercial centres. Currently 10%, 5% and 33% of the total land surfaces of Singapore, Hong Kong and Macau respectively comprise land reclaimed from the sea and these proportions will continue to rise. 相似文献
15.
Li Jiwei Wang Huabin Wei Changfu Lin Fali Liu Zizhen Zhu Zancheng 《Acta Geotechnica》2022,17(5):1803-1814
A generalized analytical solution for one-dimensional nonlinear horizontal infiltration in unsaturated soil is presented. The solution is an improved functional extremum method based on the principle of stationary action. Any prior assumption about the form of moisture diffusion functions is not implemented in the method. By considering a function of time, the water content type governing equation in the horizontal infiltration process is transformed into a function extremum problem. After solving the Euler–Lagrange equation, combined with boundary conditions, a linear relationship between the moisture diffusion function and the ratio of spatial location to the wetting-front distance is proposed. Furthermore, by using the square relationship between the wetting front and time, the spatial and temporal distribution characteristics of the water content profile are finally expressed. In contrast to most other work, the physical meanings of the parameters in this study are clear and can be derived explicitly. By utilizing the simultaneous Brooks–Corey moisture diffusion function, the development and distribution law of the water content profile was explicitly presented. The results of the solution matched well with the existing theoretical results of the four different soil samples. Owing to the high nonlinearity of the van Genuchten moisture diffusion function, the distribution of the water content profile was implicitly found based on the study method. The results obtained using this method were also consistent with the MATLAB routine, pdepe, numerical solutions for different types of soil properties.
相似文献16.
传统的边坡位移预测由于监测周期长、主要解释变量难以独立监测,存在建模困难、模型冗余、不具备空间预测能力等问题。以某半填半挖的高填方路堤边坡为研究对象,基于坡面位移实测数据,引入空间计量经济学基本理论和动态面板数据分析方法,检验和量化了不同测点间的空间关系,建立了坡面位移的动态空间面板数据模型,并进一步地检验了模型的预测结果。研究结果表明,相较于传统的时间序列模型,该模型参数更加简洁,并可同时对空间所有测点进行预测。模型不仅在时间维度有良好的预测效果,还具有一定的空间预测能力。 相似文献
17.
Claus Kohfahl Paul L. Brown Claire M. Linklater Kai Mazur Parviz Irannejad Asaf Pekdeger 《Applied Geochemistry》2008,23(12):3783-3798
The objective of this study was to investigate the impact of flow, transport and geochemical parameters in the unsaturated and saturated zones on the release of SO4 from overburden lignite spoil piles into the adjacent lake. A vertical one-dimensional model was set up using the reactive transport simulator SULFIDOX in order to account for the unsaturated zone. The SULFIDOX model was calibrated for effective diffusion using measured O2 in the gas phase and SO4 concentrations in the liquid phase from the unsaturated zone of the heap. The results show high sensitivity to O2 supply and initially present gypsum, but the inclusion of secondary mineral precipitation in equilibrium is of minor importance for the results. To account for the transport of released SO4 from the saturated zone into the surface water, scenarios were performed by using SULFIDOX results as input concentration for a two-dimensional vertical model set up with PROCESSING MODFLOW and MT3D. These scenarios indicate a rising discharge of SO4 into the adjacent lake due to continued pyrite weathering for 80 a. Results are highly sensitive to dispersivity, whereas the spatial variability of pyrite distribution did not show any influence on the results. The consideration of initially present gypsum shows a major effect on the modelled SO4 release. 相似文献
18.
The unity, interrelationship, and interdependence of the processes proceeding in anthropogenic provinces caused by the activity
of mining industries are considered from the viewpoint of the concept of hierarchical passivity of natural components. The
processes of degradation of natural complexes under the influence of mining industries and the processes of rehabilitation
of the vegetation cover when the anthropogenic pressure decreases are analyzed taking the ZAO Karabashmed’, Chelyabinsk region,
and the Severonikel’ Combine, Murmansk region, as examples. The intrinsic potential of rehabilitation of natural systems (air,
water, and soil) is assessed, and the most passive components are identified. A strategy of reclamation of disturbed territories
is enunciated based on the information obtained taking the natural self-recovering ability of ecosystems in different climate
zones into account. 相似文献
19.
Dr. J. Afolabi Falola 《GeoJournal》1987,15(1):83-90
In this paper, use is made of the multiple regression technique in an attempt to provide explanation for the pattern of adoption
of intensive poultry farming technique — an agency and infrastructure based innovation. This paper deals with two aspects
of the diffusion. The first examines the factors of spatial pattern of adoption and the second, the adoption intensity. The
paper then turns to consider the planning implications of these factors.
In Oyo State, market factor expressed as the population size of towns, distance to agency location and from previous adopters
largely account for the spatial variation in the time of adoption of ‘modern’ poultry farming technique. The intensity of
adoption (poultry population) on the other hand is influenced by the number of adopters, distance to infrastructure, profitability
considerations, literacy factor and the time of adoption. 相似文献
20.
V. S. Burtman 《Geotectonics》2010,44(5):388-404
Geological and biogeographical data on the paleooceanic basins of the Tien Shan and High Asia are summarized. The oceanic
crustal rocks in the Tien Shan, Pamir, and Tibet belong to the Tethian and Turkestan-Paleoasian systems of paleooceanic basins.
The tectonic evolution of these systems in the Phanerozoic was not coeval and unidirectional. The sialic blocks of the future
Tien Shan, Pamir, and Tibet were incorporated into the Eurasian continent during several stages. In the Late Ordovician and
Silurian several microcontinents were preliminarily combined into the Kazakh-Kyrgyz continent as a composite aggregation.
The territories of the Tien Shan and Tarim became a part of Eurasia after the closure of the Turkestan, Ural, and Paleotethian
oceans in the Late Carboniferous and Early Permian. The territories of the Pamir, Karakorum, Kunlun, and most of Tibet attached
to the Eurasian continent in the Triassic. The Lhasa and Kohistan blocks were incorporated into Eurasia in the Cretaceous,
whereas Hindustan was docked to Eurasia in the Paleogene. 相似文献