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1.
A Sustainable U.S. Energy Plan   总被引:1,自引:0,他引:1  
This report gives guidance on what could be done to overcome the political stalemate that has long blocked the creation of a sustainable energy plan, leaving the United States vulnerable to oil imports while emitting large amounts of greenhouse gases. An overall energy policy is suggested for use by political leaders, along with specific goals on climate change and national security. This report proposes a timetable by which the climate change and national security goals should be accomplished. Converting these political goals into a cost-effective energy plan that would continue to get long-term political support would be the task of the technical community. A generic process is described which applies to all future energy systems and would give guidance to the technical community on how to create a mix of energy sources and conservation. This generic process is then tested on three possible energy futures. One energy future proposes that all of our electricity should come from renewable sources within 10 years. It is shown to be inadequate and would exacerbate environmental risks. The second possible energy future adds far more nuclear energy and coal plants with carbon capture and sequestration to the above renewable-only proposal. This second plan was a significant improvement over the all-renewable energy proposal, but does not address how transportation might be accomplished in the future. Converting coal to liquid fuels is identified as the major means to produce liquid fuels, as long as non-carbon dioxide emitting sources of process heat/hydrogen are employed in this coal conversion process. The third proposal, called an Energy Family approach, places first emphasis on conservation and then creates a mix of energy sources, renewable, nuclear, coal, natural gas, and some oil that could meet all the energy demands of a modern society, while staying within environmental and national security limits. This third approach appears to be most likely to get continuing support. There can be significant progress through “Second Generation” conservation, which extracts much more energy from our existing electrical generation and transmission system. Coal would have to undergo a major transformation from producing electricity to producing liquid fuels for transportation. Transportation and space heating and cooling would be far more electrified. Nuclear power would have to be expanded to replace many of the phased out coal plants, to provide electricity for transportation, and to supply high-temperature process heat and hydrogen. Long-term programs need to be put in place to assure nuclear power’s continuing contribution. Finally, energy storage is a component which is often overlooked, but is essential. It could overcome fundamental renewable energy difficulties of variability and the possibility of wind power to create electrical grid instabilities. It is shown that an Energy Family approach could accelerate the development of renewable energy.  相似文献   

2.
The literature on shrinking cities has significantly grown in recent years. Little work, however, has been done toward the development of a shrinking city typology, which could help inform solutions and strategies to address problems associated with population loss. With a focus on central cities, this article identifies 367 shrinking cities within the United States and categorizes them using a geographic information system to identify seven types of shrinking cities in the United States: (1) large shrinking central cities, (2) inner-ring suburbs of shrinking central cities, (3) outer-ring suburbs of shrinking central cities, (4) inner-ring suburbs of growing central cities, (5) outer-ring suburbs of growing central cities, (6) small shrinking central cities in small Metropolitan Statistical Areas, and (7) small shrinking cities in small Micropolitan Statistical Areas. The empirically generated clusters, combined with associated social and demographic information, identify separate but sometimes interrelated shrinking city types and provide a new perspective for addressing the problems faced by U.S. shrinking cities. Key Words: population decline, shrinking cities, typology, urban population.  相似文献   

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本文论述了美国的外国直接投资额、外国直接投资密度和外国直接投资年增长率的地区差异,并用这三个数量指标来综合评价各州投资环境的优劣,按综合得分值的高低将美国本土划分为四类区域:Ⅰ类投资环境区、Ⅱ类投资环境区、Ⅲ类投资环境和Ⅳ类投资环境区。  相似文献   

6.
《Urban geography》2013,34(1):46-69
This paper examines the geography of institutional stock ownership for 603 major publicly traded companies. Linkages between cities are created using the stockownership levels between headquarters cities of investors and headquarters cities of firms. Both cartographic and statistical methods show that the urban connections describe a highly selective network of high-order urban centers. New York City is the dominant city, followed by Boston, Los Angeles, Philadelphia, and San Francisco. A simple gravity model, used to test the level of the effect of space on market perfection, explains a substantial portion of the investment-defined network. Differences between the levels of investment by different classes of institutional investors also are revealed.  相似文献   

7.
Factor analysis is used to examine the movement patterns of nonpermanent residents, persons who were living somewhere other than their usual residence on the April 1, 1980 census day. Movement from usual to census residences converges on the Sunbelt states of Florida, Arizona, California, Texas and Louisiana. Movement in the other direction is more dispersed as evidenced by 14 distinct patterns of census to usual residence flows.  相似文献   

8.
Abstract

This article shows how the random walk drainage network simulation model might be used as a class teaching exercise. Practical instructions about running the model are given and the results discussed. A source of directional bias in the resulting simulated drainage patterns is identified and given an interpretation in the terms of the model. Three points of educational value concerning the model are emphasized in conclusion.  相似文献   

9.
美国外资R&D的空间集聚特征   总被引:3,自引:0,他引:3  
本文考察美国境内的715家外资R&D机构的空间分布和集聚现象,发现美国的外资R&D机构高度集中在三类地区;一是以硅谷和研究三角园区为代表的科技园区,二是纽约等经济中心城市,三是以底特律为代表的专业化工业城市。不同地区的外资R&D机构的行业结构与当地的优势行业完全一致,如硅谷的外资R&D机构主要是从事计算机技术的研发,底特律的外资R&D全部是从事汽车工业或与之有关技术的研发,纽约、洛杉矶和芝加哥的外资R&D机构所从事的行业则呈现与各城市优势行业一致的多样性。  相似文献   

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As population and water demand have grown, U.S. cities have responded by expanding their water supplies. This article traces this process over a century for ten U.S. cities. Most of the cities began by providing inexpensive local ground water. As the renewable supply capacity of local sources was exceeded, cities were forced to look further afield to obtain (or purchase) water (e.g., Marion, IL; Greensboro, NC), to access water from Federal projects (Tucson, AZ) or through international or interstate agreements (Waukesha, WI and Virginia Beach, VA), to combine with other localities in large joint projects (Greensboro, NC), or to use eminent domain to annex land for a new reservoir. This last approach has become increasingly limited by environmental statutes. The purchasing of water from other systems (Greensboro, NC) or water rights ( Tucson, AZ), aquifer storage and recovery systems (Tucson, AZ, Wichita, KS), and reclaiming wastewater for use in non-potable landscaping (Alamogordo, NM; Lubbock, TX; Tucson, AZ) are the more expensive options that cities are increasingly utilizing. Desalination represents the end of this process – expensive, but with a potential for enormous supply expansion that exceeds all likely demands. Demand management measures come into play only when the cost of securing additional water begins to exceed the cost of conservation or is induced by law. Reservoirs, well-fields, desalination plants, aquifer storage and recovery systems, and inter-basin water purchases have been abandoned because of the restrictions imposed by environmental laws or because less expensive demand-side options have been identified. The relationship between city size and its progression through these increasingly expensive water supply options is determined by local water resource endowments as determined by legal considerations and its physical geographic setting.  相似文献   

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This article explores the possibility of urbanization‐ and irrigation‐induced increases in summer precipitation totals in central Arizona. Maximum precipitation impacts are hypothesized to occur downwind of the Phoenix area in the Lower Verde basin. Results from statistical tests indicate that summer precipitation totals in the Lower Verde basin are greater than totals in nearby basins. Precipitation totals in the basin also appear to be equivalent to totals at more monsoon‐impacted stations in eastern Arizona. While this research is preliminary, the results do provide encouraging evidence of the existence of anthropogenically enhanced summer precipitation in central Arizona.  相似文献   

14.
《The Journal of geography》2012,111(9):555-560
Abstract

Figures from the 1970 Soviet Census provide an abundance of information on population changes in the U.S.S.R. Of special note is the process of urbanization and a noticeable concentration of urban growth in the hitherto largely rural zones of western Russia. A large map of urban places in 1970, designed primarily for classroom use, accompanies the text (see inside back cover). The map utilizes a special stippled-sphere technique to allow a three-dimensional effect without half-tone reproduction.  相似文献   

15.
美国的区域政策及其对我国西部开发的启示   总被引:5,自引:0,他引:5  
本文分析了美国区域政策的特点:区域政策的核心是提高受援地区的社会福利;致力于改善落后的投资环境;突出重点,实施增长中心战略;注重培育欠发达地区的自我发展能力;依靠法制化管理,保障援阻工作顺利进行。在此基础上,提出解决我国地区发展不平衡问题的一些措施。  相似文献   

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本文分析了美国铁路网迅速形成和急剧缩减的原因,指出其非均衡分布的特点,介绍其远景改造设想,对我国铁路网的建设有一定的参考价值。  相似文献   

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美国波士华交通经济带的形成与演化   总被引:2,自引:0,他引:2  
本文研究了美国波士华交通经济带的形成与演化过程,分析了在不同阶段美国波士华交通经济带的生命周期特征,认为美国商业资本主义、产业资本主义的发展、高速公路的发展以及带来的集聚与扩散作用、经济服务化分别在美国波士华交通经济带的形成、发展和演化等不同阶段扮演着重要角色。波士华交通经济带是美国最大、发展最早的交通经济带,研究该地区的演化规律对我国交通经济带发展也具有借鉴作用。  相似文献   

18.
Saline playas in north-western Nevada, U.S.A., remnants of pluvial periods of the Pleistocene, represent a tremendous source of unconsolidated sediments available for aeolian transport. This study investigated the transport of aqueous-soluble solutes in dust from July 1994 through June 1996 along a transect from a barren salt-encrusted playa surface (elevation=1224 m), to a former pluvial lake beach (elevation=1228 m), to a dune-mantled upland (elevation=1248 m). The content of aqueous-soluble solutes in aeolian dust showed a significant (p≤0·05) interaction with dust trap location (playa, beach, dune) and time of collection. Dust collectors on the playa surface generally contained significantly more aqueous-soluble solutes and had greater total flux of solutes than either the beach or the dune locations. The solute content of aeolian dust was usually higher, in some cases several orders of magnitude, than that in the surface 5 cm of soil. Recent changes in playa hydrology may explain this result. Pulses of nitrate-rich dust, synchronous with spring emergence, and other nutrient additions via aeolian dust may have stimulated invasion of dune-mantled uplands by the weedSalsola paulsenii (barb-wire Russian thistle).  相似文献   

19.
The objectives of this study were to determine if metrics for ant species assemblages can be used as indicators of rangeland condition, and to determine the influence of vegetation and ground cover variables, factors often influenced by livestock grazing, on ant communities. The study was conducted in two areas in the Great Basin: a sagebrush-steppe in southeastern Idaho (n=30 sites), and a salt-desert shrub in western Utah (n=27 sites). Sites were selected based on known rangeland condition (i.e. good, fair, poor) associated with livestock grazing. Ant communities differed considerably between the two study areas. Collectively, more ant species occurred at the Idaho sites (30) than at the Utah sites (21), relatively few species (eight) occurred in both areas, species richness was significantly greater at the Idaho sites (mean=12·0 species) than the Utah sites (mean=6·9 species), and Formica spp. were diverse (total of 15 species) at the Idaho sites but rare (one species) at the Utah sites. In Idaho, all species collectively, generalists, and Formica spp. were significantly less abundant on sites in poor condition than that on sites in good or fair condition, whereas in Utah, seed harvesters and Pheidole spp. were significantly more abundant on sites in poor condition than that on sites in good or fair condition. In Idaho, species richness was significantly lower on sites in poor condition. In Idaho, species richness and relative abundances of several ant groups were significantly related to bare patch size and parameters for cover or species richness of several vegetation groups. In contrast to the comparisons involving sites in poor condition, no differences in ant communities in either Idaho or Utah were evident between sites in good and fair condition. Thus, the ant communities responded only to large changes in rangeland condition and to large differences in climatic/edaphic conditions between the two areas. Hence, ant community metrics appear to have limited utility as indicators of rangeland condition in the Great Basin.  相似文献   

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