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331.
基于格序理论的爆炸类危险化学品运输路径研究 总被引:1,自引:0,他引:1
为有效预防和减少爆炸类危险化学品运输中事故的发生,针对爆炸类危险化学品运输的路径优化选择问题,将多目标格序决策理论引入到路径方案评价比选中,构建了爆炸类危险化学品运输路径优化选择评价指标体系。结合指标选取的综合性和可操作性原则,从6个方面建立爆炸类危险化学品运输路径比选指标体系:影响区域死伤人数规模、影响区域厂矿规模、影响区域人口规模、影响区域名胜古迹保护性、影响区域生态环境保护性、影响区域综合出行费用规模。通过对各方案综合差异度的计算,实现了备选方案的格序化排序。并且在模型体系权重计算中采用了熵值法,实现了权重确定的客观性。最后,应用该模型结合实例进行了计算。 相似文献
332.
Work ability describes employees' capability to carry out their work with respect to physical and psychological job demands. This study investigated direct and interactive effects of age, job control, and the use of successful aging strategies called selection, optimization, and compensation (SOC) in predicting work ability. We assessed SOC strategies and job control by using employee self‐reports, and we measured employees' work ability using supervisor ratings. Data collected from 173 health‐care employees showed that job control was positively associated with work ability. Additionally, we found a three‐way interaction effect of age, job control, and use of SOC strategies on work ability. Specifically, the negative relationship between age and work ability was weakest for employees with high job control and high use of SOC strategies. These results suggest that the use of successful aging strategies and enhanced control at work are conducive to maintaining the work ability of aging employees. We discuss theoretical and practical implications regarding the beneficial role of the use of SOC strategies utilized by older employees and enhanced contextual resources at work for aging employees. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
333.
针对危险化学品、生化制剂、放射性或核物质( CBRN)事故情景,建立区域疏散路径优化模型。基于个体脆弱性模型,提出了适合求解模型算法,包括静态最优路径算法和动态最优路径算法。最后用随机路网测试算法的应用效果,结果表明,所提算法可以满足区域疏散路径双目标优化的需求,并能根据外部环境变化动态更新当前最优路径,是一种近似、快速的算法。区域疏散路径的确定可为CBRN事故救灾提供有力的技术支持。 相似文献
334.
Frank Van Balen 《黑龙江环境通报》2006,26(7):614-618
It appears that in most Western countries, son preference is somewhat stronger than daughter preference. However, when one considers the preference of women it looks as though the opposite pattern is emerging. There is a considerable social acceptance of ‘light’ methods of sex selection (such as diets), even though these methods are not proven to be effective. The inclination to use sperm separation methods appears to be greater in the United States than in some European countries. There are indications that a preference for boys or for girls is associated with attitudes towards technology, child-rearing style and the stereotyping of boys or girls. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
335.
Joanna M. Setchell Marie J. E. Charpentier Issa-Ben Bedjabaga Patricia Reed E. Jean Wickings Leslie A. Knapp 《Behavioral ecology and sociobiology》2006,61(2):305-315
Honest advertisement models of sexual selection propose that exaggerated secondary sexual ornaments are condition-dependent, and that only individuals with superior disease resistance will be able to express costly ornamentation. Studies of secondary sexual ornamentation and their maintenance by sexual selection tend to focus on males. However, females may also possess showy ornaments. We investigated whether female ornaments, in the form of sexual swellings, reliably signal female fitness in a semifree-ranging colony of mandrills (Mandrillus sphinx) at the Centre International de Recherches Médicales, Franceville (CIRMF), Gabon. We measured swelling height and width using photographs of periovulatory females over three mating seasons and compared swelling size with parasitism (using fecal analysis over one annual cycle), immune status (ratio of lymphocytes to neutrophils in blood smears made during captures), and genetic diversity (microsatellite heterozygosity). Swelling size varied by up to 10% between cycles in individual females, giving some support to the hypothesis that size differences may indicate the quality of individual swelling cycles. However, there was no significant difference in swelling size between conceptive and nonconceptive cycles. Measures of swelling size varied more between females than within females across swelling cycles, implying that swelling size was a relatively consistent characteristic of individual females. Swelling size was not significantly related to either general measures of parasitism and immune status, or to the closest available measures to each swelling cycle. Nor was swelling size significantly related to genetic diversity. The healthy, provisioned nature of the colony and problems associated with observational, correlational studies restrict interpretation of our data. However, in combination with previous findings that females of higher reproductive success do not show larger swellings, and that males do not allocate mating effort as a function of swelling size, these results imply that sexual swelling size does not indicate female quality in these semifree-ranging mandrills. 相似文献
336.
Atte Moilanen Michael C. Runge Jane Elith Andrew Tyre Yohay Carmel Eric Fegraus Brendan A. Wintle Mark Burgman Yakov Ben-Haim 《Ecological modelling》2006
Planning land-use for biodiversity conservation frequently involves computer-assisted reserve selection algorithms. Typically such algorithms operate on matrices of species presence–absence in sites, or on species-specific distributions of model predicted probabilities of occurrence in grid cells. There are practically always errors in input data—erroneous species presence–absence data, structural and parametric uncertainty in predictive habitat models, and lack of correspondence between temporal presence and long-run persistence. Despite these uncertainties, typical reserve selection methods proceed as if there is no uncertainty in the data or models. Having two conservation options of apparently equal biological value, one would prefer the option whose value is relatively insensitive to errors in planning inputs. In this work we show how uncertainty analysis for reserve planning can be implemented within a framework of information-gap decision theory, generating reserve designs that are robust to uncertainty. Consideration of uncertainty involves modifications to the typical objective functions used in reserve selection. Search for robust-optimal reserve structures can still be implemented via typical reserve selection optimization techniques, including stepwise heuristics, integer-programming and stochastic global search. 相似文献
337.
Models of parasite-mediated sexual selection have thus far overlooked the potential effects of parasites of females on their
hosts’ ability to choose mates. A set of models addressing this issue is developed, each building on the previous one to add
complexity and realism to the framework. The selection coefficient for parasite immunity and brightness is estimated using
the ratio of the fitness of susceptible males to the fitness of immune males. Parasite-induced reduction in female choosiness
can substantially relax the selection for bright, immune males, especially when: (1) immunity to parasites is rare in the
population, (2) parasites are not highly aggregated within the host population, (3) parasites are abundant, and (4) the effects
of parasites on male brightness or female choosiness are severe. Parasite-induced variability in male brightness is most likely
to occur in populations in which parasites are abundant and not aggregated; if females in those populations show a reduced
preference for bright males, sexual selection for brightness (and parasite immunity) will still operate but exert a weaker
selective pressure.
Received: 4 November 1994/Accepted after revision: 9 September 1995 相似文献
338.
339.
段七零 《长江流域资源与环境》2008,17(4):573-573
运用平衡方程式分析了我国各省区的原油生产消费与输入输出状况,并根据自给率,将我国26个原油流动省区划分为基本自给型、半自给型、净输出型和净补给型4种原油产需平衡类型。根据流动比率,26个省区可划归为输出中心、输入中心和交流中心3种原油流动职能类型;在分布格局上,输出中心为直角三角形,输入中心为直角梯形区,交流中心则为钝角三角形。以主要源地为标准,我国原油流动可划分为北部、西北、华东和华南四大流场,其中北部、西北属于全国性流场。我国原油流动路径可分为五大密集区,各区路径的空间结构不同:东北区为树状网络结构,华北区为单枝二叉树状结构,西北区为"X"形结构,华东区为多中心"Ⅲ"形结构,华南区则为"Y"形结构。流动路径之间还广泛存在并联与串联,充分发挥多种通道的综合流动效益。研究原油流动空间格局为我国石油空间组织的优化奠定了基础。〖 相似文献
340.
Aggregation via pheromone signalling is essential for tree-killing bark beetles to overcome tree defenses and reproduce within hosts. Pheromone production is a trait that is linked to fitness, so high individual variation is paradoxical. One explanation is that the technique of measuring static pheromone pools overestimates true variation among individuals. An alternative hypothesis is that aggregation behaviour dilutes the contribution of individuals to the trait under selection and reduces the efficacy of natural selection on pheromone production by individuals. We compared pheromone measurements from traditional hindgut extractions of female southern pine beetles with those obtained by aerating individuals till they died. Aerations showed greater total pheromone production than hindgut extractions, but coefficients of variation (CV) remained high (60-182%) regardless of collection technique. This leaves the puzzle of high variation unresolved. A novel but simple explanation emerges from considering bark beetle aggregation behaviour. The phenotype visible to natural selection is the collective pheromone plume from hundreds of colonisers. The influence of a single beetle on this plume is enhanced by high variation among individuals but constrained by large group sizes. We estimated the average contribution of an individual to the pheromone plume across a range of aggregation sizes and showed that large aggregation sizes typical in mass attacks limit the potential of natural selection because each individual has so little effect on the overall plume. Genetic variation in pheromone production could accumulate via mutation and recombination, despite strong effects of the pheromone plume on the fitness of individuals within the aggregation. Thus, aggregation behaviour, by limiting the efficacy of natural selection, can allow the persistence of extreme phenotypes in nature. 相似文献