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31.
Ricardo Harboe 《Journal of the American Water Resources Association》1992,28(1):103-110
ABSTRACT: Six applications of multiobjective decision making techniques for finding optimal or satisfying operating rules for reservoir systems are presented. The examples include situations with hydropower vs. water supply (for irrigation), flood control vs. low flow augmentation, selection of an operating rule, low-flow vs. reliability, and low flow and recreation vs. water quality. The techniques applied include the constraint method, compromise programming, goal programming, Tchebycheff approach (max-mm), Consensus, and ELECTRE I and II. 相似文献
32.
日本城市化中的耕地变动与经验 总被引:20,自引:2,他引:18
日本是一个国土面积狭小、耕地资源稀缺的国家。然而,在人均土地资源极为有限的条件下,日本在较短时间内达到了高度城市化,同时付出了较小的用地代价。在其整个城市化进程中,日本还出现了三个耕地面积增长时期。尽管各时期增长原因不尽相同,但却反映出耕地面积变动与城市化发展的密切关系。事实表明,日本选择了一条节约有限土地资源的城市化发展道路,这些经验对我国城市化发展中的耕地利用与保护有积极的借鉴意义。 相似文献
33.
依靠科学进步,促进防灾减灾 总被引:2,自引:0,他引:2
以科学技术工作为主线 ,系统地总结了陕西省减灾协会 10年来 ,从事自然灾害综合预测、防灾减灾科学研究、学术交流和科普宣传教育等方面的做法、经验和所取得的初步成效 ,以及如何建设好减灾科技社团的体会 相似文献
34.
This paper explores some ways in which differing views about the human–nature relationship reflect and are reflected in people's experiences of the places and environments they encounter in their lives. I first describe how ideas of humans being “part of” versus “apart from” nature have appeared in discussions of environmental ethics and management, and suggest how these contrasting views might relate to people's actual experiences of the natural and human aspects of places. Using qualitative survey responses about outdoor places in the midwestern USA to illustrate ideas from phenomenological and gestalt psychology, I show how a sense of the human–nature relationship is conveyed in the gestalt qualities of places and how this may give rise to a feeling of moral responsibility toward nature. I conclude that the experience of human and natural aspects of real places points toward a dialectical view of the human–nature relationship, in which humans can be seen as simultaneously “part of” and “apart from” nature. 相似文献
35.
36.
D. T. O'Laoghaire 《Journal of the American Water Resources Association》1978,14(4):809-826
ABSTRACT: This paper describes a mathematical model, an algorithm and a computer program that were specially developed to study the problem of a water quality management system undergoing a rapidly increasing environmental stress. The model output will determine the locations, sizes and the timing of construction of new treatment plants plus an overall treatment plant operating policy so that environmental standards are maintained at a minimum cost. The model, as formulated, is a 0-1 mixed integer programming problem which is solved by decomposing it into a capital budgeting problem (solved by Little's branch and bound algorithm) and an operational policy problem (solved by linear programming). The coded algorithm (in FORTRAN 10) has been tested with a semi-realistic example. 相似文献
37.
Rethinking receiver operating characteristic analysis applications in ecological niche modeling 总被引:2,自引:0,他引:2
The area under the curve (AUC) of the receiver operating characteristic (ROC) has become a dominant tool in evaluating the accuracy of models predicting distributions of species. ROC has the advantage of being threshold-independent, and as such does not require decisions regarding thresholds of what constitutes a prediction of presence versus a prediction of absence. However, we show that, comparing two ROCs, using the AUC systematically undervalues models that do not provide predictions across the entire spectrum of proportional areas in the study area. Current ROC approaches in ecological niche modeling applications are also inappropriate because the two error components are weighted equally. We recommend a modification of ROC that remedies these problems, using partial-area ROC approaches to provide a firmer foundation for evaluation of predictions from ecological niche models. A worked example demonstrates that models that are evaluated favorably by traditional ROC AUCs are not necessarily the best when niche modeling considerations are incorporated into the design of the test. 相似文献
38.
水蚯蚓能通过摄食剩余污泥而使污泥减量,但剩余污泥中常含有各种重金属污染物.本文以颤蚓科蠕虫(Tubificidae)为研究对象,以六价铬为典型重金属污染物,考察运行工艺参数:初始铬浓度、p H、水蚯蚓投加量和温度对水蚯蚓吸持六价铬的影响.实验结果表明,在研究浓度范围内(0.1~8.0 mg·L-1),水蚯蚓对六价铬的吸持速率随铬浓度的增大而加快,单位质量吸持量从14.4 mg·kg-1(以干重计,下同)增加到312.7 mg·kg-1,但六价铬的吸持率却随Cr6+初始浓度的增加而降低;p H从6.0增加到8.0,水蚯蚓对六价铬的吸持速率随p H的上升而提高,吸持率和单位质量吸持量先明显增强,p H达到7.5后逐渐趋于平衡,即吸持最佳p H为7.5;水蚯蚓投加量从1.0 g(以湿重计,下同)增加到5.0 g时,吸持速率及吸持率均上升,但单位质量吸持量却随着水蚯蚓投加量的增加而减少;当温度在10~20℃范围内时,水蚯蚓对六价铬的吸持速率相对较慢,到25℃时,吸持速率明显加快,吸持率和单位质量水蚯蚓的吸持量的变化趋势与吸持速率的变化相一致,但当温度达到30℃,水蚯蚓会大量死亡,综合考虑,处理系统最佳温度宜控制在25℃. 相似文献
39.
An Interpretive Study of Yosemite National Park Visitors’ Perspectives Toward Alternative Transportation in Yosemite Valley 总被引:1,自引:0,他引:1
White DD 《Environmental management》2007,39(1):50-62
The National Park Service (NPS) is increasingly focusing on alternative transportation systems in national parks to address
environmental and social problems arising from a historical reliance on personal automobiles as the primary means of visitor
access. Despite the potential advantages, alternative transportation may require a reorientation in the way that Americans
have experienced national parks since the advent of auto-tourism in the early twentieth century. Little research exists, however,
on visitor perspectives towards alternative transportation or the rationale underlying their perspectives. It remains unclear
how transportation systems affect visitors’ experiences of the park landscape or the factors influencing their travel behavior
in the parks. This report presents an interpretive study of visitor perspectives toward transportation management in the Yosemite
Valley area of Yosemite National Park, California. Qualitative analysis of 160 semi-structured interviews identified individual
psychological factors as well as situational influences that affect visitors’ behavior and perspectives. Individual psychological
factors include perceived freedom, environmental values and beliefs, prior experience with Yosemite National Park and other
national parks, prior experience with alternative transportation in national parks, and sensitivity to subjective perceptions
of crowding. Situational factors included convenience, access, and flexibility of travel modes, as well as type of visit,
type of group, and park use level. Interpretive communication designed to encourage voluntary visitor use of alternative transportation
should focus on these psychological and situational factors. Although challenges remain, the results of this study suggest
approaches for shaping the way Americans visit and experience their national parks to encourage environmental sustainability. 相似文献
40.
本文以标准GB/T 29309-2012为基础,以某款开关电源为例,对HALT试验设备、工作极限与破坏极限、试验步骤及设备运行中注意点等方面展开介绍,为电子产品可靠性测试提供相关探讨。 相似文献