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Sustained crude oil price increases have led to increased investment in and production of Canadian bitumen to supplement North American oil supplies. For new projects, the evaluation of profitability is based on a prediction of the future price path of bitumen and ultimately light/medium crude oil. This article examines the relationship between the bitumen and light crude oil prices in the context of a simple error-correction economic-adjustment model. The analysis shows bitumen prices to be significantly more volatile than light crude prices. Also, the dominant effect of an oil price shock on bitumen prices is immediate and is amplified, both in absolute terms and percentage price changes. It is argued that the bitumen industry response to such market risks will likely be a realignment toward vertical integration via new downstream construction, mergers, or on a de facto basis by the establishment of alliances.  相似文献   

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This article examines the Hotelling model of optimal nonrenewable resource extraction in light of empirical evidence that petroleum and minerals prices have been trendless despite resource scarcity. In particular, we examine how endogenous technology-induced shifts in the cost function would have evolved over time if they were to maintain a constant market price for nonrenewable resources. We calibrate our model using empirical data on world oil, and find that, depending on the estimate of the initial stock of reserve, oil reserves will likely be depleted some time between the years 2040 and 2075.  相似文献   

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The cold-region eco-environments along the China-Russia Crude Oil Pipeline (CRCOP) in northern Northeast China are in disequilibrium due to the combined influences of pronounced climate warming and intensive anthropogenic activities.This is evidenced by the sharp areal reduction and northward shifting of the boreal forests,shrinking of wetlands,enhancing of soil erosion,accelerating degradation of permafrost and deteriorating of cold-region eco-environments.The degradation of permafrost plays an important role as an internal drive in the eco-environmental changes.Many components of the cold-region eco-environments,including frozen ground,forests,wetlands and peatlands,forest fires and heating island effect of rapid urbanization,are interdependent,interactive,and integrated in the boreal ecosystems.The construction and long-term operation of the CRCOP system will inevitably disturb the cold-region environments along the pipeline.Therefore,a mandatory and carefully-elaborated environ-mental impact statement is indispensable for the proper mitigation of the ensued adverse impacts.Proper management,effective protection and practical rehabilitation of the damaged cold-region environments are a daunting,costly and long-term commitment.The recommended measures for protection and restoration of permafrost eco-environments along the pipeline route include adequate investigation,assessment and monitoring of permafrost and cold-region environments,compliance of pipeline construction and operation codes for environmental management,proper and timely re-vegetation,returning the cultivated lands to forests and grasslands,and effective mitigation of forest fire hazards.  相似文献   

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欧美国家绅士化问题的城市地理学研究进展   总被引:2,自引:0,他引:2  
欧洲和北美地区的绅士化研究代表着世界绅士化研究的主流与方向。在介绍绅士化的传统与衍生概念的基础上,对绅士化概念问世以来的主要理论解释派系进行分析总结,特别是从生产端和消费端进行解释的两大阵营。本文对欧美绅士化的三波发展浪潮进行介绍,并将半个世纪以来的绅士化研究划分为4 个发展阶段:绅士化现象描述阶段、两大阵营的激烈论战阶段、两种理论的相互融合阶段与绅士化政策应对研究阶段。在对绅士化作为全球城市发展战略和绅士化的主要社会空间效应做出简单评价以后,展望了世界范围内绅士化问题的研究前景;绅士化研究虽然已经走过了很长的一段路,但依然存在着巨大的研究空间。  相似文献   

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The original landform along the China-Russia Crude Oil Pipeline(CRCOP, line 2) was disturbed during installation of pavement for the pipeline. Forest and vegetation coverage is dense, and runoff develops along the pipe. Since the operation of the CRCOP(line 2) began in 2018, ponding has appeared on both sides of the pipeline. If there is no drainage,ponding can hardly dissipate, due to the low permeability of the permafrost layer. With the supply of surface flow and the transportation of oil at positive temperatures, ponding promotes an increase in temperature and changes the boundary thermal conditions of the pipeline. Meanwhile, when the ponding freezes and thaws, frost heave threatens operational safety of the pipeline. Furthermore, the ponding can affect the thermal condition of line 1. In this paper, the distribution of ponding along the CRCOP was obtained by field investigation. The type and cause of ponding were summarized, and the catchment and stream order were extracted by the Digital Elevation Model(DEM). According to the statistical results in attributes for topographic factors, it is known that ponding along the pipeline is relative to elevation, slope, aspect, and the Topographic Wetness Index(TWI). Water easily accumulates at altitudes of 300-450 m, slopes within 3°-5°, aspect in the northeast or south, TWI within 13-16, flow direction in north-east-south, and flow length within 90-150 km. This paper proposes a theoretical basis for the cause and characteristics of ponding along the pipeline.  相似文献   

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The importance of migratory caribou ( Rangifer tarandus ) to northerners, the increasing pressure to extract non-living resources, and predicted global climate change have led researchers, managers and resource users alike to focus on how to improve our knowledge of this unique northern ungulate. Unprecedented threats to caribou sustainability, along with the increasingly acknowledged value of indigenous hunters'contribution to caribou research, pose the additional challenge to innovate research methods that accommodate differing cultural perspectives and facilitate communication among groups. This paper surveys the state of scientific knowledge of the eleven major northern mainland herds of North America. We recommend an approach to improve our working knowledge of barren-ground caribou in order to assess better future impacts. The transfer of knowledge gained from years of research and indigenous experience on many aspects of caribou ecology should be evaluated and, where applicable, transferred to herds with more modest databases. The establishment of a North American Caribou Monitoring and Assessment System, based on a synthesis of local knowledge and research-based science, is recommended as a tool for improved communication and collective learning.  相似文献   

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国际旅游市场互动格局与结构特征是产业政策制定的依据,对旅游市场国际话语权的构建具有重要意义.以中国及其周边共22个国家为研究对象,采用社会网络分析法中的2-模网络和奇异值分解法对2017年国际旅游流网络结构进行刻画.结果表明:入境旅游市场互动格局中,中国发挥着主导作用,其与域内国家之间的联系度高、通达性好,且被其他国家高度依赖,处于入境旅游关系网络的核心位置.但在出境旅游市场互动格局中,菲律宾、日本、新加坡等传统旅游大国与域内其他国家间的联系相对紧密,联系的通达性条件较好,在国际旅游网络体系中发挥着重要作用,处于权力相对中心位置.进一步采用奇异值分解技术,根据中国及其周边国家间的相互作用关系,将这些国家聚类为中心环状内聚型组团、(中)南亚联动内聚型组团和西(北)亚联动扩散型组团三大类别.研究认为,中国及其周边国家在入境旅游市场和出境旅游市场的网络关系结构中,尽管传统旅游大国发挥着关键作用,构成网络体系的核心,主导着域内国际旅游发展的方向,但大国的入境旅游与出境旅游地位并不总是匹配,作为出境旅游客源国,中国在周边国家中的作用并不十分突出,需进一步提升对这些国家的影响力.  相似文献   

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As conventional oil and gas reservoirs become depleted other unconventional energy sources have to be recovered and produced. Four of the major unconventional resources that are strategic for North American interests are heavy oil, oil sands, oil shales, and coal-bed methane. Recent interest and activity in Canada’s vast oil sands are progressing rapidly as soaring oil prices are fueling a ‘gold rush’ in oil sands development in Alberta. This interest is evident by the record-number of oil sands and heavy oil presentations at Energy Minerals Division (EMD)-sponsored sessions at the 2004 and 2005 Annual Conventions of the American Association of Petroleum Geologists (AAPG), held in Dallas, TX and Calgary, AB.  相似文献   

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Farm production practices often focus on mitigating negative consequences of cropping – particularly annual crops like corn, cereals and oilseeds. Some of North America’s most-intensive farmlands are rapidly converting their remaining perennial cover to annual crops. While perennial cover like woodlands, grasslands and wetlands are valued for the many landscape services they provide, they are vulnerable to conversion to other cover types under drivers of landscape change. Conversions within farms constitute nuances rather than new land uses, yet landscape composition effects can be substantial when considering habitat, biodiversity, soil and water quality, carbon sequestration, and aesthetics. As the farm landscape becomes increasingly dominated by annual crop vegetation, the key drivers behind land cover types and management merit critical examination. This paper reviews recent studies on farmland composition and management in central Canada and the United States, identifying trajectories and magnitudes of landscape changes. To consider forces, both speculative examination of policies and information from farmer interviews help identify motivations for changes in perennial or annual proportions of farm landscapes. The paper concludes with forces that increase perennialization and existing or prospective pathways to improve the balance between annual and perennial vegetation.  相似文献   

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Calculations of dry tree, plot and regional aboveground biomass, M, and assessments of complex diverse forests remain key challenges in the implementation of conventional and sustainable projects. This study reports a set of robust regional equations and the application of several allometric tree and plot M equations in Mexican arid and semi-arid forest communities. The data were collected from 1084 tree M fitting models, and 195 arid and semi-arid and 206 mesquite trees and 55 plot datasets were used to validate the models. Theoretical, semi-empirical and empirical models with exogenous variables, as well as wood specific gravity, diameter, top height, and form-factor values, were used to evaluate aboveground biomass. Empirical computer-based equations projected more consistently similar tree M assessments than did semi-empirical or theoretical models. Therefore, empirical models are recommended for assessments of tree and plot M, and future allometry research should properly address independent variables in more theoretical models. The large sample size, model richness, economic and ecological importance, and wide coverage of this dataset make it useful for estimating several biogeochemical and bioenergy density parameters and contribute to the body of knowledge regarding heterogeneity in dry forest stand structures.  相似文献   

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The ascendance of the Pacific Rim is an indisputable global happening. North American geography, a logical leader in the study of this high profile phenomenon, has lagged behind other disciplines in Rim-focused research. This article argues in favor of a heightened Rim awareness, surveys recent publications, suggests promising Pacific Rim research directions, and proposes how the Association of American Geographers can help promote Rim studies.  相似文献   

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The deserts of North America and elsewhere may serve as ‘ecological petri dishes’ that can be used to study the general effects of global climate change (GCC) as these regions are expected to become warmer and drier at faster rates than other terrestrial regions. We highlight the biological and societal responses to such shifts in environmental parameters predicted to vary with GCC, and we introduce the term tolerance mechanism (TM) to inclusively describe the means by which organisms of natural systems or human society cope with such environmental challenges. We review the historical relationships between biological TMs and water availability, temperature, and energy resources, as well as describe societal TMs. We create a simplified conceptual model to predict the effectiveness of TMs in the context of GCC and conclude that, although currently functional, some desert TMs (e.g., biological adaptations by long-lived taxa) may be outpaced by GCC. We finish with suggested future TM-related research.  相似文献   

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Abstract

Abstract This paper provides an overview of developments and applications of geographical information systems (GIS) in North America over the past 20 years, together with some indications of lessons learned and prospects for the future. Most developments in this field have been confined to a small number of sectors, including forestry, land registry, transport and facility planning, civil engineering, agriculture and environment, although progress has been variable. The wider use of GIS has been (and will probably continue to be) inhibited by a number of factors, such as lack of digital base mapping, limited digital data, unawareness among potential users and resistance to new technology, coverage of data, assessment of costs and benefits, technological developments affecting GIS and sources of funds for research to political structures, availability of skilled staff, lack of proper advice, the unwisdom of ‘going it alone’ and management problems (which are as important as technical problems, if not more so). A successful programme of GIS depends on a coordination of effort relating to applications, trained personnel, governmental involvement in R. &D. and development of a source of independent advice.  相似文献   

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依据中美原油进口源地数据,运用网络分析法,比较了中美原油进口贸易空间结构的演化轨迹与特征。研究表明,相同的认知活动使两国的原油进口策略取向变得一致。1993年后,美中原油进口来源国数量有着几乎相同的增长趋势;但美国原油进口权重基本趋于平稳,中国原油进口权重基本处于上升通道中,同时中美贸易联系不仅存在强度上的差异,分区域的强度次序也存在重大差异;美国原油进口空间格局的权重熵经历了由高到低的演变,权重熵的比较揭示出1993年之后中国原油进口系统有序性要低于美国。以上结果表明追求多元化不应以均质化为目标,不同的主体要依据各自所面临的客观环境选择适合自己的区域合作伙伴,才能更好的落实多元化进口策略,切实解决可能面临的石油供给危机。  相似文献   

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