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排序方式: 共有994条查询结果,搜索用时 31 毫秒
931.
The Lower Rio Grande Valley (LRGV) region in South Texas emerges as a warehouse and transportation center between Central America and the US with positive growth impacts due to the North American Free Trade Agreement (NAFTA). In 10 years time, a 39.8% population increase has resulted in a 25% boost in solid waste per capita disposal rate in the region. A landfill space shortage drives a need for landfill operators to understand their optimal management strategies in this highly-competitive market. Initially, a strategic plan for optimal solid waste pattern distribution minimizes net costs for cities. This is accomplished through a grey integer programming algorithm that encapsulates all uncertainty present in the solid waste system. Secondly, a series of grey integer submodels construct payoff matrices for a zero-sum two-person game. The ensuing game theoretic analysis is critical for evaluating optimal pricing strategies for tipping fees available to the most significant regional landfills (e.g. Browning-Ferris Industries (BFI) and City of Edinburg) as they compete over disposal contracts. The BFI landfill intrinsically benefits from its competitive pricing policy and central location to solid waste generators. The City of Edinburg landfill, on the other hand, wishes to secure its lucrative solid waste management revenue. It desires a gaming strategy backed by optimality that integrates ambiguity in solid waste generation, design capacity boundaries, and unitary shipping costs. Results show that a two-tiered analysis via grey integer programming-based games may pave the way for 'grey Nash equilibria' pricing tactics that will help the Edinburg landfill maintain its waste contracts. 相似文献
932.
Eric William McMillan Earl Downey Brill 《Journal of the American Water Resources Association》1976,12(5):985-994
ABSTRACT: The cost of the liquid wast treatment measures required to meet federal as well as typical state and local regulations was examined for dairy processing plants of various sizes. Federal effluent standards were found to produce higher estimated capital costs per unit of raw material for smaller plants, even with relaxed requirements for smaller plants. State regulations limiting the effluent BOD5- concentration were also found to result in inequitable costs for smaller processors. These inequities result from economies of scale and not such factors as level of process technology employed or amount of waste produced per unit of raw material. In contrast, applying an example sewer surcharge formula did not produce inequities from economies of scale. 相似文献
933.
Carolina Milhorance Marcel Bursztyn Eric Sabourin 《Journal of Environmental Policy & Planning》2020,22(3):381-396
ABSTRACTIn the climate and land use fields, policy mixes are complex in terms of the levels of governance, actors, and roles. They consist of policy instruments that target different actors and address multiple goals across several policy sectors and levels. The analysis of these complex arrangements extends beyond purely technical efficiency criteria, as several sources of tension between instruments may be identified, such as conflicting interests, goals, and approaches to implementation. The proliferation of governance networks complicates the understanding of actors’ interactions, the types of authority influencing the outcomes of policy mixes, and importance of different levels of governance. This article provides a framework to address these analytical challenges, particularly the interconnected networks of policy actors and policy instruments. It draws on polycentric governance literature to analyse how power matters in policy networks. This includes identifying distinct types of power, actors’ position, and variables that explain patterns of conflict, competition, convergence, and divergence in policy choices and outcomes. The framework is applied to the climate and land use policies implemented in the state of Mato Grosso, Brazil. Several methods were used to clarify these variables and to characterise policy mixes being implemented in the region, including social network analysis. 相似文献
934.
Buffetaut E Grellet-Tinner G Suteethorn V Cuny G Tong H Kosir A Cavin L Chitsing S Griffiths PJ Tabouelle J Le Loeuff J 《Die Naturwissenschaften》2005,92(10):477-482
We report on very small fossil eggs from the Lower Cretaceous of Thailand, one of them containing a theropod embryo, which display a remarkable mosaic of characters. While the surficial ornamentation is typical of non-avian saurischian dinosaurs, the three-layered prismatic structure of the eggshell is currently known only in extant and fossil eggs associated with birds. These eggs, about the size of a goldfinch's, mirror at the reproductive level the retention of small body size that was paramount in the transition from non-avian theropods to birds. The egg-layer may have been a small feathered theropod similar to those recently found in China. 相似文献
935.
Eric O.Odada Daniel O.Olago Kassim Kulindwa Micheni Ntiba Shem O.Wandiga 《Ambio-人类环境杂志》2004,33(1):11-19
维多利亚湖是一个国际性水域,为沿岸社区提供着很多极其重要的环境服务,在过去50多年的时间里,该湖泊受到周边人类各项相互关联的活动越来越显著的压力,例如过度捕捞、外来物种入侵、工业污染、富营养化和泥沙淤积等.本文分析了维多利亚湖过度捕捞和污染问题产生的根源,并提出了政策性建议,这些建议有助于修复和减轻该湖的环境退化问题. 相似文献
936.
937.
938.
We evaluated stock structure and demographic (population) history of red snapper (Lutjanus campechanus) in the northern Gulf of Mexico (Gulf) via analysis of mitochondrial (mt)DNA sequences from 360 individuals sampled from four cohorts (year classes) at three localities across the northern Gulf. Exact tests of genetic homogeneity and analysis of molecular variance both among cohorts within localities and among localities were non-significant. Nested clade analysis provided evidence of different temporal episodes of both range expansion and restricted gene flow due to isolation by distance. A mismatch distribution of pairwise differences among mtDNA haplotypes and a maximum-likelihood coalescence analysis indicated a population expansion phase that dated to the Pleistocene and probably represents (re)colonization of the continental shelf following glacial retreat. The spatial distribution of red snapper in the northern Gulf appears to have a complex history that likely reflects glacial advance/retreat, habitat availability and suitability, and hydrology. Habitat availability/suitability and hydrology may partially restrict gene flow among present-day red snapper in the northern Gulf and give rise to a metapopulation structure with variable demographic connectivity. This type of population structure may be difficult to detect with commonly used, selectively neutral genetic markers.Communicated by P.W. Sammarco, Chauvin 相似文献
939.
940.
Eric Helland Andrew B. Whitford 《Journal of Environmental Economics and Management》2003,46(3):403-424
Few issues are more contentious for local communities than industrial pollution. When local industries pollute, lawmakers and regulators must balance two primary concerns: economic prosperity and the environment. The role of political pressure is well documented in environmental policy. What is less clear is the role jurisdictional or boundary considerations play in determining the implementation of environmental laws. Anecdotal evidence suggests that local regulators are more lenient in their treatment of polluters when the incidence of pollution falls partially on those outside the state. One explanation for such behavior is that regulators take actions to maximize political support. This paper tests this jurisdictional model using toxics release inventory (TRI) data from 1987 to 1996. We find that facilities’ emissions into the air and water are systematically higher in counties that border other states. These results are consistent with the hypothesis that jurisdictional considerations are an important determinant of pollution incidence. 相似文献