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71.
In order to assess the oxidation self-heating hazard of sulfurized rust, for particular ambient conditions in crude oil tanks, the support vector machine (SVM) technique is applied to predict the maximum temperature (Tmax) of oxidation self-heating process. Five governing parameters are selected, i.e. the water content, mass of sulfurized rust, operating temperature, air flow rate and oxygen concentration in the respiratory/safety valve. The efficiency and validity of the SVM predictions are investigated in the case of two sets of data: more than 85 experiments performed in academic lab (China) and almost 17 additional results collected from existing literature. Two main steps are also discussed: the training process (on selected subsets of data) and prediction process (for the remaining subsets of data). It can be concluded that for both datasets the maximum temperature (Tmax) values calculated by SVM technique were in good accordance with the experimental results, with relative errors smaller than 15% except for a few cases.The SVM technique seems therefore to be relevant and very helpful for complex implicit processes such as chemical reactions, as it is the case of the oxidation of sulfurized rust in oil tanks. Furthermore, such predictive methods can be continuously be improved through additional experiments feedback (larger databases) and can then be of crucial help for monitoring and early warning of hazardous reactions. 相似文献
72.
《Environmental Communication: A Journal of Nature and Culture》2013,7(3):243-260
This essay offers the weyekin principle to address the symbol–material, human–nature dualisms found in much of our theory and critiqued by a growing number of environmental communication scholars. The authors see two core requirements for transforming our engagement with the nonhuman: first, a way of attending to or interpreting natural phenomena that opens our awareness to other-than-symbolic modes of experience; and second, an embodied critique that expresses the inherent tensions of the symbolic–material interface. 相似文献
73.
This essay responds to the keynote address by Cox by discussing the ways in which critical rhetoric is implicated in environmental communication (EC) as a crisis discipline, as well as the ways in which EC, so positioned, is implicated within a broader coherentist epistemology. Issues of exigency, representation, and sustainability are considered, along with an examination of the concepts of nominalism and doxa as they relate to the enterprise of EC research. The critical cultural politics embedded in much EC scholarship are also addressed in terms of their intersections with the increasingly unscrupulous abuse of language within antienvironmental administrative rhetorics. 相似文献
74.
75.
Global challenges have exacerbated a search for solutions to poverty and environmental degradation. Integration it was argued would help address the twin challenge. Integrated Water Resources Management (IWRM) was supposed to be that magic bullet and was embraced by scientists because of the clinical efficiency with which it argued for integrated analysis of sectors and resources and of systems and scale conditions. This paper argues that effective implementation of the Water-Energy-Food (WEF) Nexus can be supported by robust science. The corollary that robust science automatically leads to effective implementation is not always known to be true. The nexus approach sheds light on the challenges of implementation by introducing concepts of trade-offs and thresholds and consequently emphasizes the importance of transdisciplinary approaches to sustainable development. This paper reviews the results of recent research to offer tentative answers to the following questions: (a) Why is the governance dimension important to undertake an integrated analysis of water-energy-food challenges? (b) What does the nexus approach connote in normative and institutional terms? (c) What does implementation mean in nexus terms? (d) How can we establish if the nexus approach is an improvement over business as usual? and (e) What tools are available that would enable translation of results of scientific research to create an evidence base that would enable decision makers to act in support of sustainable development? 相似文献
76.
The tolerance of terrestrial ecosystems of the Kola Peninsula to atmospheric deposition of acid-forming sulfur compounds and the risk of their excess input into these ecosystems have been assessed on the basis of the critical load concept. The most sensitive ecosystems (critical sulfur load <400 equiv/ha per year) occupy 58% of the total area of the peninsula. These are mainly pine, spruce, and birch forests (including open and crooked birch forests) growing on podzols formed on sandy boulder-pebble glacial deposits. The zones of ecological risk cover the northwestern and central parts of the peninsula near the Pechenganikel and Severonikel combined works (20% of the total area). 相似文献
77.
George R. Holdren Jr. Timothy C. Strickland Bernard J. Cosby David Marmorek David Bernard Robert Santore Charles T. Driscoll Linda Pardo Carolyn Hunsaker Robert S. Turner John Aber 《Environmental management》1993,17(3):355-363
The critical loads approach is emerging as an attractive means for evaluating the effects of atmospheric deposition on sensitive
terrestrial and aquatic ecosystems. Various approaches are available for modeling ecosystem responses to deposition and for
estimating critical load values. These approaches include empirical and statistical relationships, steady-state and simple
process models, and integrated-effects models. For any given ecosystem, the most technically sophisticated approach will not
necessarily be the most appropriate for all applications; identification of the most useful approach depends upon the degree
of accuracy needed and upon data and computational requirements, biogeochemical processes being modeled, approaches used for
representing model results on regional bases, and desired degree of spatial and temporal resolution. Different approaches
are characterized by different levels of uncertainty. If the limitations of individual approaches are known, the user can
determine whether an approach provides a reasonable basis for decision making. Several options, including point maps, grid
maps, and ecoregional maps, are available for presenting model results in a regional context. These are discussed using hypothetical
examples for choosing populations and damage limits.
The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared
at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental
Technology, Inc., and Interagency Agreement #1824-B014-A7 with the U.S. Department of Energy and at Oak Ridge National Laboratory
managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental
Sciences Division Publication No. 3904. It has been subjected to the agency’s peer and administrative review and approved
for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献
78.
Carolyn Hunsaker Robin Graham Robert S. Turner Paul L. Ringold George R. Holdren Jr. Timothy C. Strickland 《Environmental management》1993,17(3):335-341
The United States Environmental Protection Agency, with support from the US Department of Energy and the National Oceanographic
and Atmospheric Administration, has been evaluating the feasibility of an effects-based (critical loads) approach to atmospheric
pollutant regulation and abatement. The rationale used to develop three of the six steps in a flexible assessment framework
(Strickland and others, 1992) is presented along with a discussion of a variety of implementation approaches and their ramifications.
The rationale proposes that it is necessary to provide an explicit statement of the condition of the resource that is considered
valuable (assessment end point) because: (1) individual ecosystem components may be more or less sensitive to deposition,
(2) it is necessary to select indicators of ecosystem condition that can be objectively measured and that reflect changes
in the quality of the assessment end point, and (3) acceptable status (i.e., value of indicator and quality of assessment
end point at critical load) must be defined. The rationale also stresses the importance of defining the assessment regions
and subregions to improve the analysis and understanding of the indicator response to deposition. Subregional definition can
be based on a variety of criteria, including informed judgment or quantitative procedures. It also depends on the geographic
scale at which exposure and effects models are accurate and on data availability, resolution, and quality.
The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared
at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental
Technology, Inc., and Interagency Agreement #1824-B014-A7 with the US Department of Energy and at Oak Ridge National Laboratory
managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental
Sciences Division Publication No. 3903. It has been subjected to the agency’s peer and administrative review and approved
for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献
79.
Ronald A. Chadderton Arthur C. Miller Archie J. McDonnell 《Journal of the American Water Resources Association》1981,17(5):760-766
A study was made to analyze and modify procedures used for stream assimilation capacity and point source wasteload allocation calculations. This paper describes the sources and types of information collected and the analysis of alternative computation methods developed during the study. The calculation of stream assimilation capacity or Total Maximum Daily Load (TMDL), will depend upon assumed stream flows, quality standards, reaction rates, and modeling procedures. The “critical conditions” selected for TMDL calculations usually are low flows and warm temperatures. The complexity of water quality models used for TMDL and allocation calculations can range from simple, complete mixing to calibrated and verified mathematical models. A list of 20 wasteload allocation (WLA) methods was developed. Five of these WLA's were applied to an example stream to permit comparisons based on cost, equity, efficient use of stream assimilation capacity, and sensitivity to fundamental stream quality data. Based on insensitivity to data errors and current use by several states, the WLA method of “equal percent treatment” was preferable in the example stream. 相似文献
80.
Arturo A. Keller Yi Zheng Timothy H. Robinson 《Journal of the American Water Resources Association》2004,40(3):721-735
ABSTRACT: Traditional approaches to establishing critical water quality conditions, based on statistical analysis of low flow conditions and expressed as a recurrence interval for low flow conditions (e.g., 7Q10), may be inappropriate for drier watersheds. The use of 7Q10 as a standard design flow assumes year‐round flow, but in these watersheds, 7Q10 is zero or very small. In addition, the increasing use of multiple year dynamic water quality models at daily time steps can supercede the use of steady state approaches. Many of these watersheds are also under increasing urbanization pressure, which accentuates the flashiness of runoff and the episodic nature of critical water quality conditions. To illustrate, the conditions in the Santa Clara River, California, are considered. A statistical analysis indicates that higher inorganic nitrogen concentrations correlate strongly with low flow. However, peaks in concentrations can occur during the first storms, particularly where nonpoint source contribution is significant. Critical conditions can thus occur at different flow regimes depending on the relative magnitude of flow and pollutant contributions from various sources. The use of steady state models for these dry semi‐urbanized watersheds based on 7Q10 flows is thus unlikely to accurately simulate the potential for exceeding water quality objectives. Dynamic simulation of water quality is necessary, and as the recent intense storm event sampling data indicate, the models should be formulated to consider even smaller time steps. This places increasing demand on computational resources and datasets to accurately calibrate the models at this temporal resolution. 相似文献