预紧力对输电塔节点承载能力特性研究∗

为探讨风荷载作用下输电塔破坏机理,本文以实际输电塔体系为例,通过建立不同螺栓预紧力作用下输电塔节点精细化模型,用来进行输电塔的螺栓在实际工程中拧紧程度的模拟;提出了螺栓与输电塔各构件之间的非线性接触力模型,研究了风荷载作用下输电塔构件之间接触效应的精确模拟.结果 表明:随着预紧力的增大,斜材螺孔应力、节点板上相对位于斜材处螺孔应力和斜材螺栓应力逐渐增大,并基本呈线性变化;而主材螺孔应力、节点板上相对位于主材处螺孔应力和主材螺栓应力基本不变.可见随着外荷载加载比例逐渐增大,螺栓预紧力对节点承载力性能的影响逐渐减小.     

Specific biomagnification of polychlorinated dibenzo-p-dioxins and dibenzofurans in tufted ducks (Aythya fuligula), common cormorants (Phalacrocorax carbo) and their prey from Lake Shinji,Japan

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/DFs) were detected in waterfowl such as common cormorants, tufted ducks, and their prey, namely fish and bivalves from Lake Shinji, Japan. The concentration of total PCDDs/DFs-TEQ was found to be higher in the muscle tissues of common cormorants than in those of tufted ducks. The results of hierarchical cluster analysis implied that the residue distribution pattern of PCDD/DF homologues was considerably different between these two species. Furthermore, biomagnification factors (BMFs) were estimated from bivalves as prey to tufted duck muscles as target organs. Despite the highest concentrations of 1,3,6,8- and 1,3,7,9-TeCDD in tufted ducks and their prey, however, the BMFs of these isomers were calculated to be lower than those of the toxic 2,3,7,8-substituted PCDDs/DFs. On the other hand, log BMF of toxic 2,3,7,8-substituted PCDDs/DFs were significantly higher for lower chlorinated isomers than those of the higher chlorinated isomers. The biota-sediment accumulation factors (BSAFs) of PCDDs/DFs were also estimated using shijimi clam and fish samples against sediment from Lake Shinji. The average BSAFs were estimated and ranged from 4.0×10⁻³ to 2.2×10⁻¹ and 2.0×10⁻⁴ to 2.0×10⁻¹ for bivalve and fish samples, respectively. Based on calculated BMFs and BSAFs, the total PCDD/DF-TEQ levels in the tufted duck were estimated to have been lowest (2.0 pg TEQ/g dry weight basis) in 1947 and highest (9.8 pg TEQ/g) in 1971.     

中国化工产业佩尔兹曼效应实证研究

近年来中国化工产业事故频发,由此引发的安全、健康和环境问题日益突出.为了探讨化工事故产生的深层原因,建立了VECM对中国化工产业的佩尔兹曼效应进行检验.结果表明,短期看中国化工安全设施加强并没有显著提高化工安全水平的原因在于存在佩尔兹曼效应;长期看工人逆向选择的抵消效应趋于消失;化工工人安全意识薄弱是导致短期内安全设施投资加大、事故率不降反升的主要原因之一.该结论为完善化工安全规制政策提供了理论支撑.     

Warning signals confer advantage to prey in competition with predators: bumblebees steal nests from insectivorous birds

Aposematic (warning) signals of prey help predators to recognize the defended distasteful or poisonous prey that should be avoided. The evolution of aposematism in the context of predation has been in the center of modern ecology for a long time. But, the possible roles of aposematic signals in other ecological contexts have been largely ignored. Here we address the role of aposematic signals in competition between prey and predators. Bumblebees use visual and auditory aposematic signals to warn predators about their defenses. For 2 years, we observed competition for nestboxes between chemically defended insects, Bombus ardens (and possibly also Bombus ignitus), and cavity nesting birds (Parus minor and Poecile varius). Bumblebees settled in 16 and 9 % of nestboxes (in 2010 and 2011 breeding seasons, respectively) that contained bird nests at the advanced stage of nest building or at the stage of egg laying. Presence of bumblebees prevented the birds from continuing the breeding activities in the nestboxes, while insects took over the birds’ nests (a form of kleptoparasitism). Playback experiments showed that the warning buzz by bumblebees contributed to the success in ousting the birds from their nests. This demonstrates that aposematic signals may be beneficial also in the context of resource competition.     

Positive relationships between phenol oxidase activity and extractable phenolics in estuarine soils

Decomposition of recalcitrant materials such as phenolics is known to play a pivotal role in organic matter decomposition and nutrient cycling in estuaries. The specific goals of this study were to determine temporal and spatial variations of phenol oxidase and phenolics in estuarine soils, and to elucidate controlling factors for phenol oxidase activity. To achieve these goals, phenol oxidase activity and phenolic content were measured in soils developed along the side of an estuary in the Han River, Korea. Soil samples were collected in three locations with different vegetation: mud flats, Zizania-dominated soils, and Salix-dominated soils. Monthly measurements were also made in a Zizania-dominated site over a year period. Phenol oxidase activity varied between 0.00 and 0.28 diqc min^?1 g^?1, whilst phenolic content ranged from 0.0–10.5 μg g^?1. A correlation analysis revealed that phenol oxidase activity exhibited positive correlations with phenolic content in both seasonal and spatial data. The same relationship was found when the data were analysed separately for each site. Unlike peatlands or upland forest soils where negative correlations were often found between phenol oxidase activity and phenolics, substrate induction appears to account for the positive correlation in the present study.     

Genes and song: genetic and social connections in fragmented habitat in a woodland bird with limited dispersal

Understanding the processes leading to population declines in fragmented landscapes is essential for successful conservation management. However, isolating the influence of disparate processes, and dispersal in particular, is challenging. The Grey Shrike-thrush, Colluricincla harmonica, is a sedentary woodland-dependent songbird, with learned vocalizations whose incidence in suitable habitat patches falls disproportionally with decline in tree cover in the landscape. Although it has been suggested that gaps in tree cover might act as barriers to its dispersal, the species remains in many remnants of native vegetation in agricultural landscapes, suggesting that it may have responded to habitat removal and fragmentation by maintaining or even increasing dispersal distances. We quantified population connectivity of the Grey Shrike-thrush in a system fragmented over more than 120 years using genetic (microsatellites) and acoustic (song types) data. First, we tested for population genetic and acoustic structure at regional and local scales in search of barriers to dispersal or gene flow and signals of local spatial structuring indicative of restricted dispersal or localized acoustic similarity. Then we tested for effects of habitat loss and fragmentation on genetic and acoustic connectivity by fitting alternative models of mobility (isolation-by-distance [the null model] and reduced and increased movement models) across treeless vs. treed areas. Birds within -5 km of each other had more similar genotypes and song types than those farther away, suggesting that dispersal and song matching are limited in the region. Despite restricted dispersal detected for females (but not males), populations appeared to be connected by gene flow and displayed some cultural (acoustic) connectivity across the region. Fragmentation did not appear to impact greatly the dispersal of the Grey Shrike-thrush: none of the mobility models fit the genetic distances of males, whereas for females, an isolation-by-distance model could not be rejected in favor of the models of reduced or increased movement through treeless gaps. However, dissimilarities of the song types were more consistent with the model of reduced cultural connectivity through treeless areas, suggesting that fragmentation impedes song type sharing in the Grey Shrike-thrush. Our paper demonstrates that habitat fragmentation hinders important population processes in an Australian woodland bird even though its dispersal is not detectably impacted.     

职业中毒场所盲目施救行为的心理因素分析与对策研究

探讨职业中毒场所因盲目施救引发伤亡事故扩大的原因及控制对策,为企业和相关部门实施有效的安全管理提供依据。采用分析归纳方法,界定盲目施救行为。依据突发事件引发的紧急情况的特点,分析得出有限作业空间发生的中毒窒息事故属于常规突发事件。盲目施救导致伤亡扩大事故发生的主要行业和作业特性显示,安全监管的疏漏是事故发生的原因。根据社会心理学理论,对中毒人员的施救属于利他行为,盲目施救是人在应激状态下失控的冲动行为,这一行为与人对不安全行为的预期后果相关,应急知识和能力的缺乏是导致盲目施救行为发生的主要原因。根据上述研究结论,提出避免常规突发事件引发盲目施救行为的对策。     

基于博弈论石化园区火灾跨区域灭火救援研究

为解决石油化工园区火灾跨区域灭火救援面临的多消防中队相互协作、消防资源优化配置等复杂问题,搭建以新疆阿克苏地区消防力量为救援基础的原油储罐火灾场景,结合Gambit软件建立博弈计算模型,设计跨区域灭火救援方案的通用流程。针对不同火灾规模,以跨区域灭火救援通用制定流程为指导,计算出相应的消防中队战斗组合及救援力量输出。针对火灾发展的不确定性,通过混合策略博弈计算进一步调整和完善跨区域灭火救援方案。结果表明,采用博弈论方法能够提供针对消防资源调度分配的新方法,用以制定更快速和易于调整的灭火救援方案。