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Gateway cities have received much attention from urban geographers. In spite of outstanding contributions being made, we think that the concept needs to be revisited with regard to regional development implications. Bringing together research on global production networks (GPNs) and world cities, this article shows that gateway cities are critical for development in networks, generating impulses for peripheral locations by engaging them in processes of “strategic coupling.” Yet, gateway cities also concentrate segments of GPNs to the detriment of their hinterlands. We conceptualize gateway cities with the aid of five features: logistics and transport, industrial processing, corporate control, service provision and knowledge generation. Our concept allows for an understanding of cities in global and regional economic processes beyond corporate headquarters, corporate services and governance – that is, beyond the boundaries of existing research. It unsettles traditional understandings of strategic coupling and world cities, filling a lacuna on city–hinterland connections. 相似文献
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Fathe Bouteldja Pierre Breul Daniel Boissier 《Geotechnical and Geological Engineering》2011,29(6):1009-1021
Domestic wastewater-treatment system is today a widely held technique. In order to evaluate the efficiency of these systems,
it is necessary to determinate the in situ hydraulic conductivity of the water-treatment granular materials constituting them.
The in situ measurement of the hydraulic conductivity of soils has proven to be imprecise, take a long time. Empirical equations
based on the physical properties of soil have been proposed to overcome these difficulties. In this context, the originality
of this paper is to propose an in situ method to obtain reliable input parameters for the predictive equations of Chapuis
(Can Geotech J 41(5): 787–795, 2004) and Carrier (J Geotech Geoenviron Eng 129(11): 1054–1056, 2003) by using both a penetrometer and a geoendoscope. This method is described in the first part of this paper. Then, the validation
of the method based on laboratory tests performed under controlled conditions for three kinds of soils is presented. Hydraulic
conductivity obtained when applying the method is compared to that measured by a Darcy permeameter. The difference between
these two hydraulic conductivities is less than 25%. Finally, the precision of the results is discussed. 相似文献
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A. Gabriel Villavicencio Pierre Breul Claude Bacconnet Daniel Boissier A. Raúl Espinace 《Geotechnical and Geological Engineering》2011,29(6):1073-1084
Dams are often used for storing mine tailings. These structures present failure mechanisms that can lead to major risks for
surrounding populations. In view to managing these risks, it is necessary to take a probabilistic approach in predicting their
behaviour. The application of such approaches is limited by the difficulty of obtaining experimental data to estimate the
variability of the parameters and conditioned by the relevance of the probability models chosen to represent this variability.
This article proposes (1) a probabilistic modelling of the index properties of the mine tailings constituting these dams based
on statistical analyses and (2) a method using dynamic penetration tests to estimate on site the mine tailings friction angle
and its variability. This method, applied to chilean tailings dams proposes a single model for all tailings dams in order
to associate a probability law to the effective friction angle (ϕ′). The procedure is illustrated on the probabilistic study
of slope stability carried out at the global scale of a dam and also at the local scale of each of its constituent layers. 相似文献
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Natural Hazards - Extensive research has addressed the question of why some countries are able to attract a large amount of foreign direct investment (FDI), while others are not. Until now, this... 相似文献
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ABSTRACTSkempton coefficient B is commonly used to evaluate the saturation of a sample before the shearing stage in a triaxial test. For unsaturated soils, measuring the degree of saturation Sr at the end of the consolidation stage is very difficult whereas measuring Skempton coefficient B is very simple. Using this coefficient to obtain Sr of a sample in a triaxial apparatus without complex procedures might be an improvement, especially as regards testing procedures for unsaturated soils. Different authors have proposed a relationship between these two parameters based on the hypothesis that a variation of B coefficient with Sr is mostly due to the compressibility of air in the pores. However, the presence of air as a fluid phase gives rise to suction after the equilibrium is reached inside the sample leading to an increase in stiffness. Based on this observation, this article presents a new relationship that enables Sr to be evaluated with a given Skempton coefficient taking into account not only the initial void ratio and the isotropic elastic modulus but also the suction and the elastoplastic behaviour of the soil. The results of the proposed approach are then confronted with the original relationship and compared to experimental data. 相似文献
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