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David Demeritt 《Geoforum》2004,35(6):655-660
The increasing emphasis of UK higher education policy on formal research training and the acquisition of employment-related skills by Ph.D. students raises important questions about the purpose of the Ph.D. This paper raises concerns about the prevailing instrumentalism of government policy and urges academics to become more actively engaged in the ongoing debates about the nature and role of research training and the appropriate balance between the Ph.D. as a developmental process of study and apprenticeship and as a substantive contribution to knowledge.  相似文献   

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The Grassfields of Cameroon is a fertile ground for self-help efforts. This paper examines the resurgence and role Village Development Associations (VDAs) are playing in national and community development. Community members are increasingly shouldering the adverse consequences of the economic downturn and the growing inability of the state to provide economic and social development by initiating, mobilising and galvanising their own resources in the quest for improving their standard of living. The reliance on indigenous technology and local human resources has led to overwhelming popular participation in community- driven development. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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New forms of hazards generated by extreme weather pose new challenges to emergency management. The purpose of this paper is to identify a typical evolution dynamics by analyzing coupling and embeddedness in risk evolution via critical infrastructure system under extreme weather. Evidence from the snow event in early 2008, China, is used to draw the viewpoint and support the argument. The paper identifies the dynamics that how a natural hazard of extreme weather evolves into a social crisis and how coupling and embeddedness contribute to the evolution. This paper makes it evident that the impact of natural hazard to a society can obtain amplification through coupling and embeddedness. Therefore, new challenges in risk evolution should become a highlighted direction for further research. This paper sheds light on a new profile for social impact research of natural hazard and provides new insights into systems thinking on emergency management.  相似文献   

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由市场细分显现建筑装饰专业化管理的重要性   总被引:1,自引:0,他引:1  
随着中国国民经济持续稳定的发展以及人民生活水平的不断提高,尤其是作为国民经济五大支柱产业之一的建筑业及房地产业的迅猛发展,作为建筑业重要分支行业-建筑装饰业的需求日益扩大,给装饰企业提供了持续、良好的市场前景。  相似文献   

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The central theme of this paper is the issue of the governance of cooperation within the Chilean wine industry. The effects of the internationalization of this industry for the importance and the quality of governance of intra-cluster cooperation involving firms and other actors are analysed. Two questions stand central. First, what has been the relative importance of external and internal factors in improving the export performance of the Chilean wine industry over the past 20 years? Second, to what extent have collective actions and investments played a part in this growth, and what has been the quality of the various governance regimes dealing with the associated collective action problems? Empirical evidence suggests that world-market developments and upgrading efforts by individual wineries largely explain the good export performance of the Chilean wine industry until the year 2000. The evidence also shows that the industry’s success in world markets is stimulating cooperation between firms and other actors in areas where the industry needs to improve: marketing and promotion, internationalization, innovation and training. The enhanced cooperation has not only stimulated cluster development, but has also turned the quality of cluster governance into a central variable for future export growth. Nevertheless, several collective action problems await resolution before essential intra-cluster cooperation can develop. Overall, the evidence suggests that, in the case of the Chilean wine industry, industrial and cluster development do not automatically follow enhanced integration in world markets, but depend on the strategic skills of actors within the industry, in particular their ability to identify, prioritize, and realize collective investments while effectively managing the associated collective action problems. Internationalization stimulates firms to consider such investments, however, and provides them with an incentive to upgrade strategic skills at the local level as new opportunities arise and the pressure is there to exploit them in world markets.  相似文献   

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The dating of Quaternary sedimentary records provides detailed information for understanding the response of Earth surface environments to climate change and human activity. Although its roots lie in the most fundamental of geological principles, palaeoenvironmental research is an essential component of present-day global environmental change research.  相似文献   

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The high seismicity of portions of the Indian peninsula, together with the high density of population and industrial growth, results in a significant seismic risk in many parts of the subcontinent. Large construction projects throughout the peninsula require an adequate basis for earthquake-resistant design. Thus, as well as strong scientific arguments, there are major practical reasons why a substantial programme to record strong seismic ground motion should be carried out in India. This paper first reviews the history of strong motion instrumental recording, beginning with the important accelerograms obtained in the Koyna earthquake of 11 December 1969 through the recent increase in strong motion instrumentation, particularly in association with construction of large dams. It is argued that there is a pressing need for further extension of strong motion accelerograph coverage of India, especially along the seismically active regional thrust faults of the Himalayan region. Such programme expansion should follow deliberate strategies of site selection, designed to optimize the scientific and practical returns, given the requirements of minimum costs, reliable maintenance and accessible data.  相似文献   

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The numerical dissipation characteristics of the Newmark and generalised-α time-integration schemes are investigated for P-wave propagation in a fully saturated level-ground sand deposit, where higher frequencies than those for S-waves are of concern. The study focuses on resonance, which has been shown to be of utmost importance for triggering liquefaction due to P-waves alone. The generalised-α scheme performs well, provided that the time-step has been carefully selected. Conversely, the dissipative Newmark method can excessively damp the response, changing radically the computed results. This implies that a computationally prohibiting small time-step would be required for Newmark to provide an accurate solution.  相似文献   

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A 3D geological model of the area east of Basel on the southeastern border of the Upper Rhine Graben, consisting of 47 faults and six stratigraphic horizons relevant for groundwater flow, was developed using borehole data, geological maps, geological cross sections, and outcrop data. This model provides new insight into the discussions about the kinematics of the area between the southeastern border of the Upper Rhine Graben and the Tabular Jura east of Basel. A 3D analysis showed that both thin-skinned and thick-skinned tectonic elements occur in the modeled area and that the Anticline and a series of narrow graben structures developed simultaneously during an extensional stress-field varying from E–W to SSE–NNW, which lasted from the Middle Eocene to Late Oligocene. In a new approach the faults and horizons of the 3D geological model were transferred into discrete elements with distributed hydrogeological properties in order to simulate the 3D groundwater flow regime within the modeled aquifers. A three-layer approach with a horizontal regularly spaced grid combined with an irregular property distribution of transmissivity in depth permitted the piezometric head of the steady-state model to be automatically calibrated to corresponding measurements using more than 200 piezometers. Groundwater modeling results demonstrated that large-scale industrial pumping affected the groundwater flow field in the Upper Muschelkalk aquifer at distances of up to 2 km to the south. The results of this research will act as the basis for further model developments, including salt dissolution and solute transport in the area, and may ultimately help to provide predictions for widespread land subsidence risks.  相似文献   

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Conclusions As developing countries expand both agricultural and industrial activities over the coming decade, sensitive management of the limited available freshwater resources will become increasingly important. If their supplies consist solely of ground water, then some water deficit countries could end up by mining a non-renewable resource as it takes many thousands of years to replenish deep fossil groundwater stocks. Conservation and careful husbandry of existing stocks must therefore be carried out if the growing human populations of arid lands are to be protected from famine and poverty.The arid zones may provide more than sufficient food in a sustainable system despite the harsh natural conditions. In arid areas rainfall is low, biological cycling is limited by low soil moisture and evapotranspiration is high. The absence of leaching by infiltration results in a large active pool of nutrients and the addition of water by irrigation allows this potential fertility to be realised. Given the high insolation of desert lands and a man-made continuous water supply it is possible to obtain 2–4 crop harvest a year. However, the success of any future development is ultimately in the hands of the governments who control the management of water resources.Until recently pollution of the sea was relatively localised. It has now become a problem globally around coasts and even affects the open ocean. Enclosed and semi-enclosed seas are most vulnerable to degradation of their ecosystems and the Golf region has proved to be no exception to this, sensitivity exacerbated by weak currents and political instability leading to increasing oil pollution.The pollution in the Gulf is at its most harmful in the biologically diverse and productive areas around coastlines where pollution tends to concentrate and where human welfare is also most at risk. The outbreak of cholera and other waterborne disease in Iraq immediately following the Gulf war highlights the exceptional reliance people throughout the Gulf States must place of fresh water supplies. Continuing political instability in the region and its associated environmental damage will not, therefore, only threaten wildlife or fisheries but may threaten human welfare as water supplies are limited or decline in quality and industry, agriculture and health all suffer the consequences.  相似文献   

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Flow-through experiments have been performed to study the thermodynamics of biogenic silica (opal) dissolution in deep-sea sediments. They were applied for the first time on sediment from the Southern Ocean [Van Cappellen and Qiu 1997a] and [Van Cappellen and Qiu 1997b] We have extended the use of these experiments to other deep-sea settings, thereby covering a wide range of in situ silicic acid asymptotic concentrations (Casympt; 200 to 900 μmol/L) and biogenic opal content (BSi; 0.5 to 80%). Performing these experiments under in situ bottom temperatures allows for the comparison between experimental apparent solubilities and Casympt concentrations. Low values of BSi apparent solubilities have been measured in the deepest sections of the multicores collected in the northeast Atlantic (229 μmol/L) and in the equatorial Pacific (505 μmol/L). They are only 10 to 20% higher than the in situ Casympt concentrations. This demonstrates a clear control of pore water silicic acid concentrations by the in situ apparent solubility of the BSi, i.e., the solubility of BSi within a complex sedimentary matrix that includes important quantities of silicate minerals.In regions where the percentage detrital/percentage biogenic ratio is low, the apparent solubility of the biogenic silica is close to that of in situ biogenic silica. In the opposite case, when the percentage detrital/percentage biogenic ratio is high, reprecipitation reactions induce strong interference on the dissolution properties of the opal, both in situ and in flow-through experiments. In such a sedimentary matrix, it is important to determine the appropriate opal solubility to be used in early diagenetic models, i.e., the solubility of the biogenic silica just before deposition on the seabed. This has been achieved by performing flow-through experiments on sediment trap material from the north Atlantic site. Comparison of apparent biogenic silica solubility measured by flow-through experiments and the silicic acid concentrations measured in the cups of the sediment traps suggested that the solubility of biogenic silica that reaches the sediment-water interface is not unique and varies spatially and temporally. In fact, it is the degree of coupling between surface waters and the sediment-water interface that will control the aging of biogenic silica in the water column and hence the dissolution properties of the biogenic silica deposited at the sediment-water interface. All these results call for a strong improvement of biogenic silica early diagenetic models that should include not only a reprecipitation term that takes into account interaction with silicate minerals but also the existence of several phases of biogenic silica and thus that should operate in a non-steady-state mode to account for seasonal variations in the quality of deposited biogenic silica.  相似文献   

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Elke Knappe 《GeoJournal》1998,46(3):243-246
Agriculture has ceased to be the major employer in the rural areas of East Germany. Far-reaching structural change has resulted in a sharp decrease in employment and the mono-structural character of villages has been lost. Unemployment is now a major problem and women are worst affected. New jobs have been created in construction and elsewhere in the tertiary sector but most people who have found new jobs have to commute to the towns or migrate permanently to the urban areas. A north-south contrast has developed because the more developed network of towns in the latter, combined with a relatively good infrastructure, has enabled many villages to survive as viable communities. An example is Fuchshain near Leipzig where employment with the farming company (the former cooperative with 4200 ha of land) has declined but the population has grown through new housing built for commuters. In the north there has been much depopulation and many houses are used as second homes. Either way there is more conflict occurring now within rural communities because of tensions between the employed and the unemployed and between old and new residents. It is therefore important that land use planning should take into account the changed economic and social profiles and measures should be adopted to ensure that the countryside remains visually attractive and socially cohesive. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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Image-based 3D modeling has recently opened the way to the use of virtual outcrop models in geology. An intriguing application of this method involves the production of orthorectified images of outcrops using almost any user-defined point of view, so that photorealistic cross-sections suitable for numerous geological purposes and measurements can be easily generated. These purposes include the accurate quantitative analysis of fault-fold relationships starting from imperfectly oriented and partly inaccessible real outcrops. We applied the method of image-based 3D modeling and orthorectification to a case study from the northern Apennines, Italy, where an incipient extensional fault affecting well-layered limestones is exposed on a 10-m-high barely accessible cliff. Through a few simple steps, we constructed a high-quality image-based 3D model of the outcrop. In the model, we made a series of measurements including fault and bedding attitudes, which allowed us to derive the bedding-fault intersection direction. We then used this direction as viewpoint to obtain a distortion-free photorealistic cross-section, on which we measured bed dips and thicknesses as well as fault stratigraphic separations. These measurements allowed us to identify a slight difference (i.e. only 0.5°) between the hangingwall and footwall cutoff angles. We show that the hangingwall strain required to compensate the upward-decreasing displacement of the fault was accommodated by this 0.5° rotation (i.e. folding) and coeval 0.8% thickening of strata in the hangingwall relatively to footwall strata. This evidence is consistent with trishear fault-propagation folding. Our results emphasize the viewpoint importance in structural geology and therefore the potential of using orthorectified virtual outcrops.  相似文献   

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“Pressure solution”, frequently found in clay-rich sandstone, is characterized by enhanced quartz dissolution at inter-grain contacts. The origin of pressure solution and many other related dissolution processes remains elusive. Using an Electrochemical Surface Forces Apparatus we visualized and measured the dissolution of silica glass surfaces close to an electrode surface. The dissolution rates correlate quantitatively with the electrode potential via the Butler-Volmer equation for corrosion. Our experimental results demonstrate that at low temperature, apparent pressure solution and many other mineral dissolution phenomena can be driven by electrochemical processes rather than a pressure-driven process. This finding highlights the role of electrochemical surface potentials in dissolution phenomena at dissimilar material interfaces, and provides new perspectives on pressure solution in particular and a new theoretical basis for predictive control of dissolution phenomena in general.  相似文献   

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Based on the results of the Conference on Resource Assessment Techniques of IGCP Project 98 in Loen, Norway, 1976, the importance of mineral and energy inventories is demonstrated by their long-term objectives which aim at the solution of problems of quantitative and qualitative mineral and energy reserve and resource assessments, estimates of the exploration potential, supply analysis, future land-use planning, and national mineral policy. Prior to establishing a mineral and energy inventory it is essential to clearly define both the long-term and short-term objectives, because they control the scope of an inventory and determine the approach to and the method of constructing the data base. Only then can questions be answered as to the kind of data required, the advantages of regional-versus commodity-based inventories, the necessity of computer-processable data files, the availability of a user-oriented data base management system, and the usefulness of conducting a pilot project. Examples are given for simple and complex types of mineral and energy inventories. The “Mineral Deposit Inventory” of the Institute for Geosciences and Natural Resources, Hannover, Federal Republic of Germany, serves mainly as an information and reference system, whereas the mineral inventory of “Project Manitoba” of the Geological Survey of Canada forms the base for reserve and resource assessment as well as land-use planning of that province. For developing and industrialized countries alike, mineral and energy inventories are appropriate tools in planning new exploration activities and decisions on future national mineral policy. Used by the Regional Mineral Resources Development Centers of ESCAP and ECA, the United Nations economic commissions in Asia and Africa, these tools could be of great advantage and mutual benefit to the developing countries of those regions. This paper was presented at the International Geological Correlation Program (IGCP) Project 98: “Standards for Computer Applications in Resource Studies” held at Taita Hills, Kenya, November 8–15, 1977.  相似文献   

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For accurate mathematical modeling of trace-element partitioning during igneous fractionation, adsorption should be considered. Because of adsorption, the partitioning of elements between liquid and a surface layer of a crystal is often not the same as the partitioning between liquid and the solid crystal at true equilibrium. In some minerals e.g. high-calcium pyroxene, the effect of adsorption during crystal growth may be very important; this is suggested by the frequent occurrence of sector zoning in augite, and the wide range in measured partition coefficients for such elements as rare earths. The ions which are enriched by adsorption are usually those which are favored substituents according to Goldschmidt's rules. In other minerals, uptake of trace elements may be closer to equilibrium partitioning, rather than being determined by kinetic factors. For example, the relative partitioning of REE, U, Th and Pb into feldspars is qualitatively predicted by Pauling's rules for complex ionic crystals, rather than by Goldschmidt's rules.  相似文献   

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