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241.
为合理选择应急物流配送中心地址,提高应急管理能力,基于地震灾害风险评价数据,通过ArcGIS平台形成Voronoi图,可视化表达地震应急准备分区方案并进行应急物流中心预选址;在考虑需求权重情况下,构建应急物流配送中心优化选址模型,通过LINGO软件编程求解得出基于震灾应急准备分区的应急物流配送中心选址方案,并以A市为例,通过与传统行政区划建设方案进行对比,验证本文选址方案的有效性。研究结果表明:本文选址优化模型综合考虑各方面因素,使服务里程总量减少31.39%,单位服务量提高30.61%,验证选址方案的配送效率与公平性。 相似文献
242.
243.
Deepti Puri R. Karthikeyan M. Babbar‐Sebens 《Journal of the American Water Resources Association》2009,45(4):928-944
Abstract: The two main rivers of southeast Texas: Guadalupe and San Antonio have shown high temporal increase in bacteria concentration during the last decade. The SPAtially Referenced Regression On Watershed (SPARROW) attributes model, developed by the U.S. Geological Survey (USGS), has been applied to predict the fluxes and concentrations of contaminants in unmonitored streams and to identify the sources of these contaminants. This model identifies every reach as a basic network unit to distribute the sources, delivery, and attenuation factors. The model is data intensive and implements nonlinear regression to solve the parsimonious relations for describing various watershed processes. This study explored watershed and hydrological characteristics (land uses, precipitation, human and animal population, point sources, areal hydraulic load and drainage density, etc.) as the probable sources and delivery mechanisms of waterborne pathogens and their indicator (Escherichia coli [E. coli]) in the Guadalupe and San Antonio River basins. The effect of using various statistical indices for model selection on the final model’s ability to explain the various E. coli sources and transport processes was also analyzed. 相似文献
244.
A. Peters L. B. Astheimer C. R. J. Boland A. Cockburn 《Behavioral ecology and sociobiology》2000,47(6):438-445
Testosterone has been proposed as a physiological link between the level of sexual signalling and male condition. Bright plumage
is one of the most noticeable sexual signals and is often used by females as a basis for mate choice. Yet bright male plumage
is not necessarily testosterone dependent. We investigated the role of testosterone in the moult into seasonal nuptial plumage
in male superb fairy-wrens. Early pre-nuptial moult is under intense intersexual selection and males can acquire the bright
plumage any time between autumn and the next spring. Testosterone was always undetectable or very low in males in dull eclipse
plumage. During the pre-nuptial moult, both the number of males with detectable testosterone and average testosterone levels
increased sharply. High testosterone was more correlated with nuptial plumage than with presence of the cloacal protuberance
(indicative of sperm storage). Subcutaneous testosterone implants always induced the pre-nuptial moult within 2–3 weeks after
implantation, even well outside the natural time range of moulting. Moreover, removal of the implants before the nuptial plumage
was completed, arrested the moult process. The evidence suggests that development of the nuptial plumage is testosterone dependent,
although we cannot exclude that testosterone exerts its action after conversion to a metabolite such as oestrogen. Once the
nuptial plumage was completed, all males maintained substantially elevated testosterone, sometimes months before the onset
of breeding. These high levels could be necessary to maintain the plumage, and/or are involved in courtship displays. The
results are discussed with respect to potential costs involved in acquiring and maintaining the nuptial plumage.
Received: 17 January 2000 / Received in revised form: 24 February 2000 / Accepted: 25 February 2000 相似文献
245.
An analytic network process approach for locating undesirable facilities: an example from Istanbul, Turkey 总被引:5,自引:1,他引:4
Locating an undesirable facility is a sophisticated problem, for the evaluation procedures involve several objectives and the solution to the problem calls for some compromises to be made between probable conflicting criteria. This paper addresses the problem of undesirable facility location selection using the analytic network process (ANP), a multi-criteria decision-making technique. The ANP technique enables us to consider both qualitative and quantitative criteria as well as the interdependencies and feedbacks. A number of criteria (benefits, opportunities, costs and risks) and their sub-criteria are considered for siting a new facility with which this study has dealt. The questions of what criteria would be considered and what the interdependencies between these criteria and their weights would be were discussed and determined via interviews with some competent authorities of the Istanbul Municipality and of two environmental organizations. Four representative locations were evaluated and the most convenient one was selected. This was followed by the sensitivity analyses of the results. 相似文献
246.
Analytic hierarchy process helps select site for limestone quarry expansion in Barbados 总被引:1,自引:1,他引:0
Site selection is a key activity for quarry expansion to support cement production, and is governed by factors such as resource availability, logistics, costs, and socio-economic-environmental factors. Adequate consideration of all the factors facilitates both industrial productivity and sustainable economic growth. This study illustrates the site selection process that was undertaken for the expansion of limestone quarry operations to support cement production in Barbados. First, alternate sites with adequate resources to support a 25-year development horizon were identified. Second, technical and socio-economic-environmental factors were then identified. Third, a database was developed for each site with respect to each factor. Fourth, a hierarchical model in analytic hierarchy process (AHP) framework was then developed. Fifth, the relative ranking of the alternate sites was then derived through pair wise comparison in all the levels and through subsequent synthesizing of the results across the hierarchy through computer software (Expert Choice). The study reveals that an integrated framework using the AHP can help select a site for the quarry expansion project in Barbados. 相似文献
247.
Background, Aim and Scope
Metal ions generally share the ability/tendency of interacting with biological material by forming complexes, except possibly for the heavy alkali metals K, Rb and Cs. This is unrelated to the metals being either essential for sustaining life and its reproduction, apparently insignificant for biology, although perhaps undergoing bioconcentration or even being outright toxic, even at low admission levels. Yet, those different kinds of metal-biomass interactions should in some way depend on properties describing coordination chemistries of these very metals. Nevertheless, both ubiquitously essential metals and others sometimes used in biology should share these properties in numeric terms, since it can be anticipated that they will be distinguished from nonessential and/or toxic ones. These features noted above include bioconcentration, the involvement of metal ions such as Zn, Mg, Cu, Fe, etc. in biocatalysis as crucial components of metalloenzymes and the introduction of a certain set of essential metals common to (almost) all living beings (K, Mg, Mo, Mn, Fe, Cu and Zn), which occurred probably very early in biological evolution by ‘natural selection of the chemical elements’ (more exactly speaking, of the metallomes).Materials and Methods
The approach is semiempirical and consists of three consecutive steps: 1) derivation of a regression equation which links complex stability data of different complexes containing the same metal ion to electrochemical data pertinent to the (replaced) ligands, thus describing properties of metal ions in complexes, 2) a graphical representation of the properties-two typical numbers c and x for each metal ion-in some map across the c/x-space, which additionally contains information about biological functions of these metal ions, i.e. whether they are essential in general (e.g. Mg, Mn, Zn) or, for a few organisms of various kinds (e.g. Cd, V), not essential (e.g. rare earth element ions) or even generally highly toxic (Hg, U). It is hypothesized that, if coordination properties of metals control their biological ‘feasibility’ in some way, this should show up in the mappings (one each for mono and bidentate-bonding ligands). 3) eventually, the regression equation produced in step 1) is inverted to calculate complex stabilities pertinent to biological systems: 3a) complex stabilities are mapped for ligands delivered to soil (-water) by green plants (e.g. citrate, malate) and fungi and, compared to their unlike selectivities and demands of metal use (photosynthesis taking place or not), 3b) the evolution of the metallome during late chemical evolution is reconstructed.Results
These maps show some ‘window of essentiality’, a small, contrived range/area of c and x parameters in which essential metal ions gather almost exclusively. c and x thus control the possibility of a metal ion becoming essential by their influencing details of metal-substrate or (in cases of catalytic activities) metal-product interactions. Exceptions are not known to be involved in biocatalysis anyhow.Discussion
Effects of ligands secreted, e.g. from tree roots or agaric mycelia to the soil on the respective modes (selectivities) of metal bioconcentration can be calculated by the equation giving complex stability constants, with obvious ramifications for a thorough, systematic interpretation of biomonitoring data. Eventually, alterations of C, N and P-compounds during chemical evolution are investigated — which converted CH4 or CO2, N2 and other non-ligands to amino acids, etc., for example, with the latter behaving as efficient chelating ligands: Did they cause metal ions to accumulate in what was going to become biological matter and was there a selectivity, a positive bias in favour of nowessential metals (see above) in this process? Though there was no complete selectivity of this kind, neither a RNA world in which early ribozymes effected most of biocatalysis, nor a paleoatmosphere containing substantial amounts of CO could have paved the way to the present biochemistry and metallomes.Conclusions
This way of reasoning provides a causal account for abundance distributions described earlier in the Biological System of Elements (BSE; Markert 1994, Fränzle &; Markert 2000, 2002). There is a pronounced change from chemical evolution, where but few transformations depended on metal ion catalysis to biology.Recommendations and Perspectives
The application of this numerical approach can be used for modified, weighted evaluation of biomonitoring analytical data, likewise for the prediction of bioconcentration hazards due to a manifold of metal ions, including organometallic ones. This is relevant in ecotoxicology and biomonitoring. In combining apoproteins or peptides synthesized from scratch for purposes of catalysing certain transformations, the map and numerical approaches might prove useful for the selection of central ions which are even more efficient than the ‘natural’ ones, like for Co2+ in many Zn enzymes.248.
Models that predict distribution are now widely used to understand the patterns and processes of plant and animal occurrence as well as to guide conservation and management of rare or threatened species. Application of these methods has led to corresponding studies evaluating the sensitivity of model performance to requisite data and other factors that may lead to imprecise or false inferences. We expand upon these works by providing a relative measure of the sensitivity of model parameters and prediction to common sources of error, bias, and variability. We used a one-at-a-time sample design and GPS location data for woodland caribou (Rangifer tarandus caribou) to assess one common species-distribution model: a resource selection function. Our measures of sensitivity included change in coefficient values, prediction success, and the area of mapped habitats following the systematic introduction of geographic error and bias in occurrence data, thematic misclassification of resource maps, and variation in model design. Results suggested that error, bias and model variation have a large impact on the direct interpretation of coefficients. Prediction success and definition of important habitats were less responsive to the perturbations we introduced to the baseline model. Model coefficients, prediction success, and area of ranked habitats were most sensitive to positional error in species locations followed by sampling bias, misclassification of resources, and variation in model design. We recommend that researchers report, and practitioners consider, levels of error and bias introduced to predictive species-distribution models. Formal sensitivity and uncertainty analyses are the most effective means for evaluating and focusing improvements on input data and considering the range of values possible from imperfect models. 相似文献
249.
发展资源再生产业是中国资源战略的一场革命 总被引:1,自引:0,他引:1
中国已经成为资源消耗大国,实施再生型资源战略,发展循环经济是我国的必然选择。资源再生产业与“循环经济”取代“线性经济”、经济全球化形成“国际大分工”和“国际大循环”的发展趋势同步,是解决资源和环境问题的根本出路。资源再生产业是一座“富矿”,没有“资源再生”就没有中国的“环境保护”。中国资源再生产业的发展为什么步履艰难?它和进口渠道不畅。国民对资源短缺认识不足、传统的“线性思维方式”的影响,来自国内外“利益集团”的阻力,以及政策不刭位等因素密切相关。因此,提出中国发展资源再生产业的对策和建议:①在经济相对滞后、交通便利的地区建立“资源再生加工区”;②建立畅通的全球物质回收“绿色通道”;③建立“国际再生资源交易市场”;④成立“国际资源再生促进会”;⑤改变“线性经济”背景下的传统观念。 相似文献
250.
Most models of habitat selection assume that individual animals choose and either reuse or abandon sites based on a constant
reassessment of site quality. When survival is a function of the presence of conspecifics, however, the benefits of returning
to traditional sites may override resource assessment. Many animals form roosting aggregations at what appear to be traditional
sites. At our study site in Nicaragua, the harvestman Prionostemma sp. forms diurnal roosting aggregations on a small subset of the available spiny palm trees. With respect to physical characteristics
and microclimate, the spiny palms used by the harvestmen resembled a random sample of those available, yet the same subset
of trees was used in two different years (2001, 2003). This suggests that the location of aggregation sites is traditional,
not a product of habitat limitation. Individual harvestmen were not faithful to particular roost sites, however, which raises
the question of how the tradition could be maintained over time. In this paper, we present evidence, derived from a series
of small-scale field experiments, that the harvestmen mark roosting sites chemically and enter marked sites preferentially
when searching for places to roost. We also show that the harvestmen are sensitive to changes in site quality (the presence
of spines) but will continue to use degraded traditional sites when no intact spiny palms are nearby. This system provides
an example of how animal traditions could be maintained over multiple generations without learning. Site-labeling can be viewed
as an external form of social memory. 相似文献