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271.
简要介绍汽车排放污染物种类及其对人体的危害,阐述了现有汽车排放控制的技术措施,分析了汽车排放后处理技术存在的主要问题,提出汽车排放控制系统的设计方案,并对方案的可行性进行了分析研究. 相似文献
272.
P -V因数是对摩擦副在边界润滑状态下工作 ,而规定的一个设计准则。由于磨损失效是XB型轴向柱塞泵的主要失效形式 ,所以 ,笔者提出 ,通过引用P -V因数的广义概念 ,建立起磨损可靠性基本设计的模型 ,并对XB -F4 0型轴向柱塞泵的滑履进行磨损可靠性设计。较成功地改善了摩擦副的磨损状况 ,提高了XB -F4 0型轴向柱塞泵的使用寿命 ,同时提供了一种可靠性设计的新思路。 相似文献
273.
274.
The International Safety Management (ISM) Code defines a broad framework for the safe management and operation of merchant ships, maintaining high standards of safety and environmental protection. On the other hand, ISO 14001:2004 provides a generic, worldwide environmental management standard that has been utilized by several industries. Both the ISM Code and ISO 14001:2004 have the practical goal of establishing a sustainable Integrated Environmental Management System (IEMS) for shipping businesses. This paper presents a hybrid design methodology that shows how requirements from both standards can be combined into a single execution scheme. Specifically, the Analytic Hierarchy Process (AHP) and Fuzzy Axiomatic Design (FAD) are used to structure an IEMS for ship management companies. This research provides decision aid to maritime executives in order to enhance the environmental performance in the shipping industry. 相似文献
275.
Rebecca Lave 《Journal of the American Water Resources Association》2009,45(6):1519-1532
Lave, Rebecca, 2009. The Controversy Over Natural Channel Design: Substantive Explanations and Potential Avenues for Resolution. Journal of the American Water Resources Association (JAWRA) 45(6):1519‐1532. Abstract: The controversy over Natural Channel Design (NCD) has perplexed, and sometimes paralyzed, the stream restoration community in the United States for more than a decade. Despite the high level of energy expended by participants on both sides, the content of the discussion has not advanced significantly. The two sides seem to be talking past each other, rather than engaging in constructive conversation. This paper attempts to start that conversation. Based on five years of primarily social science research, this paper explains the key components of the NCD approach, evaluates a number of the most common objections raised by its critics, offers a brief explanation for the widespread use of NCD, and concludes with suggestions about how to bring the controversy to a close. 相似文献
276.
Only with a properly designed water quality monitoring network can data be collected that can lead to accurate information
extraction. One of the main components of water quality monitoring network design is the allocation of sampling locations.
For this purpose, a design methodology, called critical sampling points (CSP), has been developed for the determination of
the critical sampling locations in small, rural watersheds with regard to total phosphorus (TP) load pollution. It considers
hydrologic, topographic, soil, vegetative, and land use factors. The objective of the monitoring network design in this methodology
is to identify the stream locations which receive the greatest TP loads from the upstream portions of a watershed. The CSP
methodology has been translated into a model, called water quality monitoring station analysis (WQMSA), which integrates a
geographic information system (GIS) for the handling of the spatial aspect of the data, a hydrologic/water quality simulation
model for TP load estimation, and fuzzy logic for improved input data representation. In addition, the methodology was purposely
designed to be useful in diverse rural watersheds, independent of geographic location. Three watershed case studies in Pennsylvania,
Amazonian Ecuador, and central Chile were examined. Each case study offered a different degree of data availability. It was
demonstrated that the developed methodology could be successfully used in all three case studies. The case studies suggest
that the CSP methodology, in form of the WQMSA model, has potential in applications world-wide. 相似文献
277.
Kalikhman I 《Environmental monitoring and assessment》2007,129(1-3):197-206
A mathematical model is used to examine the effects of choosing various units of sampling distance of a spiral acoustic survey
on the adequacy of reconstructing patchy distribution fields. The model simulates fish or plankton patches (or gaps) of different
shapes and spatial orientations, and an acoustic survey by a spiral of Archimedes along which a unit of sampling distance
is set. For comparison, surveys are imitated by parallel transects along which the same unit of sampling distance is set.
Adequacy of the reconstructed fields to those originally generated is evaluated by calculating their correlations (r). In the case of a spiral survey, the mathematical experiments conducted show that an immovable field can be reconstructed
properly (r
2 > 0.70) if the ratio of the units of sampling distance to the autocorrelation radius for the field averaged in various directions
d/R
av < 1.0–1.5. Regarding immovable fields, the spiral surveys ensure, practically speaking, the same adequacy of the field reconstruction
as do surveys by parallel transects with the same unit of sampling distance. In regard to movable fields, a comparison of
the results of spiral surveys with those of surveys by parallel transects indicates that the former may ensure even higher
adequacy of the field reconstruction than do the latter, provided that the units of sampling distances in these surveys are
equal to each other. 相似文献
278.
Ohman KV Hettiaratchi JP Ruwanpura J Balakrishnan J Achari G 《Environmental monitoring and assessment》2007,135(1-3):85-97
The application of scientifically based decision making tools to help address solid waste management issues dates back to
the early 1960s. Researchers continue to use operations research tools to help optimize landfill design and operating parameters.
This paper discusses the application of another type of decision making tool, the analytical hierarchy process (AHP), to address
priority ranking for a number of landfill engineering design and operating objectives in developing and developed countries.
In this application, the AHP is used to rank, and prioritize, economic, environmental, health and safety, legislative and
public perception objectives for landfill design and operations specific to landfill distance from a community, and precipitation
levels. Results from a global survey using the Delphi process are included, with a discussion on the survey’s impact on the
objective rankings relative to community proximity and precipitation. The Delphi process worked extremely well, and was an
excellent tool to use in this application. The initial results from the objective rankings show promise in the development
of an integrated model for landfill design and operation. 相似文献
279.
Kalikhman I 《Environmental monitoring and assessment》2007,124(1-3):243-252
A mathematical model was used to examine the effects of a spiral survey design on the adequacy of reconstructing patchy distribution
fields. The model simulates fish or plankton patches (or gaps) of different shapes and spatial orientations, and acoustic
surveys by a spiral of Archimedes; for comparison, surveys by parallel or zigzag transects are imitated. Adequacy of the reconstructed
fields to those originally generated was evaluated by calculating their correlations (r). The mathematical experiments conducted
showed that spiral surveys ensure, practically speaking, the same adequacy of field reconstruction (both in cases of immovable
or movable patches) as do surveys by parallel or zigzag transects with greater sampling effort (overall path). In the case
of a spiral survey, a patchy field can be reconstructed properly (r2 = 0.70) if the overall survey path is not less than S/Rav = 20–30, where Rav is the autocorrelation radius averaged for various directions. Thus, the results obtained allow us to conclude that a spiral
survey design is expedient in cases that the minimal duration of a survey is a decisive factor for its conduction and there
is a priori information that no onshore-offshore gradients of fish density exist in a region under study. 相似文献
280.
累积影响监测系统初步设计 总被引:3,自引:0,他引:3
累积影响监测和适应性管理是减少和改善累积影响评价不确定性的重要途径之一。文章初步探讨了累积影响监测的概念,提出了累积影响监测系统的设计原则,从内容、时空范围、监测指标、监测结果的表达、实施机构、实施程序等多方面对累积影响监测系统进行了初步探讨。 相似文献