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401.
Refaul FerdousFaisal Khan Rehan SadiqPaul Amyotte Brian Veitch 《Journal of Loss Prevention in the Process Industries》2012,25(1):8-19
Bow-tie analysis is a fairly new concept in risk assessment that can describe the relationships among different risk control parameters, such as causes, hazards and consequences to mitigate the likelihood of occurrence of unwanted events in an industrial system. It also facilitates the performance of quantitative risk analysis for an unwanted event providing a detailed investigation starting from basic causes to final consequences. The credibility of quantitative evaluation of the bow-tie is still a major concern since uncertainty, due to limited or missing data, often restricts the performance of analysis. The utilization of expert knowledge often provides an alternative for such a situation. However, it comes at the cost of possible uncertainties related to incompleteness (partial ignorance), imprecision (subjectivity), and lack of consensus (if multiple expert judgments are used). Further, if the bow-tie analysis is not flexible enough to incorporate new knowledge or evidence, it may undermine the purpose of risk assessment.Fuzzy set and evidence theory are capable of characterizing the uncertainty associated with expert knowledge. To minimize the overall uncertainty, fusing the knowledge of multiple experts and updating prior knowledge with new evidence are equally important in addition to addressing the uncertainties in the knowledge. This paper proposes a methodology to characterize the uncertainties, aggregate knowledge and update prior knowledge or evidence, if new data become available for the bow-tie analysis. A case study comprising a bow-tie for a typical offshore process facility has also been developed to describe the utility of this methodology in an industrial environment. 相似文献
402.
This research compares two existing methodologies, mixed trophic impact analysis and utility analysis, which use network analysis to evaluate the direct, pair-wise, and indirect, holistic, ecological relations between ecosystem compartments. The two approaches have many similarities, but differ in some key assumptions which affect both the final results and interpretations. Here, we briefly introduce both methodologies through a series of two simple examples; a 3-compartment competition model and a 3-compartment food chain model, and then apply the methodologies to a 15-compartment ecosystem model of the Chesapeake Bay. This example demonstrates how implementing the various conceptual and methodological assumptions lead to differing results. Notably, the overall number of positive relations is greatly affected by the treatment of the self-interactions and the handling of detritus compartments lead to a distinction between ecological or trophic relations. We recommend slight changes to both methodologies, not necessarily in order to bring them completely together, but because each has some points which are stronger and better defensible. 相似文献
403.
We explored the utility of incorporating easily measured, biologically realistic movement rules into simple models of dispersal. We depart from traditional random walk models by designing an individual-based simulation model where we decompose animal movement into three separate processes: emigration, between-patch movement, and immigration behaviour. These processes were quantified using experiments on the omnivorous insect Dicyphus hesperus moving through a tomato greenhouse. We compare the predictions of the individual-based model, along with a series of biased random walk models, against an independent experimental release of D. hesperus. We find that in this system, the short-term dispersal of these insects is described well by our individual-based model, but can also be described by a 2D grid-based biased random walk model when mortality is accounted for. 相似文献
404.
In this study, we tested the tendency of young cichlids to orient towards their parents using chemical cues. Convict cichlids
have biparental defence of their free-swimming young. If young become separated from their family they must rejoin their family
within minutes to have any chance of survival. Here, we used a dichotomous Y-maze to test if displaced convict cichlid young
can use chemical cues to orient to their family. First, we showed that young preferentially orient toward water taken from
their home tank versus blank water taken from a tank that contained no fish. Second, we showed that young prefer home tank
water to water from a tank containing another family of convict cichlids. In a third experiment, we placed young convict cichlids
in a small aquarium inserted within a larger aquarium. The large aquarium contained either their parents or no fish. The small
insert aquarium contained blank water from a tank that had never contained fish. After 20 min in the insert tank, young convict
cichlids were placed in the Y-maze and given a choice between either their home tank water or water from the insert tank.
Convict cichlids that did not see their parents during the 20-min conditioning period oriented strongly toward chemical cues
of their home tank water. Young that saw their parents during the 20-min conditioning period oriented strongly toward the
chemical cues of the insert tank. These data indicate that young convict cichlids use visual cues to learn and reset the smell
of “home” in less than 20 min. 相似文献
405.
Michael G. Hadfield Brian T. Nedved Sean Wilbur M. A. R. Koehl 《Marine Biology》2014,161(11):2577-2587
Larvae of many sessile marine invertebrates settle in response to surface microbial communities (biofilms), but the effects of soluble compounds from biofilms in affecting larval behavior prior to settlement, attachment, and metamorphosis have been little studied. This question was addressed by videotaping the behavior of competent larvae of the serpulid, Hydroides elegans, above settlement-inducing biofilms. Adult worms were collected in Pearl Harbor, Hawaii, USA in November 2012 and spawned almost immediately. Six-day old larvae were placed in five replicated treatments in small cups: (1) with a natural biofilm; (2) with a natural biofilm on an 8-µm screen, 1 mm above the bottom of a clean cup; (3) with a natural biofilm beneath a clean screen; (4) in a clean cup; and (5) in a clean cup with a clean screen. Using the videotapes, larval swimming speeds and trajectories were quantified within 5 min of the larvae being placed in a treatment. Only larvae that touched a biofilm, i.e., in treatments (1) and (2), slowed their swimming speed and increased the amount of time spent crawling rather than swimming. This shows that under these conditions, any soluble cues emanating from a biofilm do not affect settlement behavior. Furthermore, after 24 h close to 100 % of larva in the two accessible biofilm treatments had metamorphosed and <15 % in treatments that included a biofilm under a clean screen and no biofilm at all, strongly suggesting that soluble cues for settlement were not produced by the biofilms over the longer time period. 相似文献
406.
Brian J. Yates Ramona Darlington Radek Zboril Virender K. Sharma 《Environmental Chemistry Letters》2014,12(3):413-417
Perfluoroalkyl and polyfluoroalkyl substances are occurring in consumer and industrial products. They have been found globally in the aquatic environment including drinking water sources and treated wastewater effluents, which has raised concern of potential human health effects because these substances may be bioaccumulative and extremely persistent. The saturated carbon–fluorine bonds of the substances make them resistant to degradation by physical, chemical, and biological processes. There is therefore a need for advanced remediation methods. Iron-based methods involving high-valent compounds are appealing to degrade these substances due to their high oxidation potentials and capability to generate environmentally friendly by-products. This article presents for the first time the oxidation ability of tetraoxy anions of iron(V) (FeVO4 3?, Fe(V)), and iron(IV) (FeIVO4 4?, Fe(IV)), commonly called ferrates, in neutral and alkaline solutions. Solid compounds of Fe(V) (K3FeO4) and Fe(IV) (Na4FeO4) were added directly into buffered solution containing perfluorooctansulfonate and perfluorooctanoic acid at pH 7.0 and 9.0, and mixed solutions were subjected to analysis for remaining fluoro compounds after 5 days. The analysis was performed by liquid chromatography–mass spectrometry/mass spectrometry technique. Fe(IV) showed the highest ability to oxidize the studied contaminants; the maximum removals were 34 % for perfluorooctansulfonate and 23 % for perfluorooctanoic acid. Both Fe(V) and Fe(IV) had slightly higher tendency to oxidize contaminants at alkaline pH than at neutral pH. Results were described by invoking reactions involved in oxidation of perfluorooctansulfonate and perfluorooctanoic acid by ferrates in aqueous solution. The results demonstrated potentials of Fe(V) and Fe(IV) to degrade perfluoroalkyl substances in contaminated water. 相似文献
407.
408.
409.
The MicroBlower Sustainable Soil Vapor Extraction System is a cost‐effective device specifically designed for remediation of organic compounds in the vadose zone. The system is applicable for remediating sites with low levels of contamination and for transitioning sites from active source technologies such as active soil vapor extraction to natural attenuation. It can also be a better choice for remediating small source zones that are often found in “tight zones” that are controlled by diffusion rate. The MicroBlower was developed by the Savannah River National Laboratory at the US Department of Energy's Savannah River Site to address residual volatile organic compound (VOC) contamination after shutdown of active soil vapor extraction systems. In addition, the system has been deployed to control recalcitrant sources that are controlled by diffusion rates. © 2012 Wiley Periodicals, Inc. 相似文献
410.
Evolutionary Significant Units versus Geopolitical Taxonomy: Molecular Systematics of an Endangered Sea Turtle (genus Chelonia) 总被引:2,自引:0,他引:2
Abstract: Taxonomic rank is an important criterion in assessing the conservation priority of an endangered organism: the sole member of a distinct family will generally receive a higher priority than a semi-isolated population in a polytypic species. When cryptic evolutionary partitions are discovered in endangered species, these findings are heralded as a positive step in the conservation process. The opposite action, demoting the taxonomic rank of an endangered organism, can be resisted by the conservation community because it is perceived as detrimental to preservation efforts. We explore the arguments for and against the species status of the endangered black turtle ( Chelonia agassizii ) and contribute an additional data set based on DNA sequences of single-copy nuclear loci. These data are concordant with previous mtDNA surveys in indicating no evolutionary distinction between C. agassizii and adjacent green turtle ( C. mydas ) populations. Although the black turtle is morphologically identifiable at a low level, much of its distinction is based on size and color differences that are highly variable throughout the range of C. mydas . Thus the black turtle would be more accurately classified at the subspecific or population level. There is no strong scientific case available to defend the species status of C. agassizii , and yet that designation has persisted for over a century. We suggest that the maintenance of this name is based on geographical and political considerations, and we propose a pragmatic category for this type of taxonomy: the geopolitical species . Furthermore, we argue against the practice of preserving species status for conservation purposes. There are several good reasons to preserve the black turtle, including morphological diversity and the possibility that it is an incipient evolutionary lineage with novel adaptations; taxonomic rank, however, is not one of them. 相似文献