障碍物排列方式对海洋平台蒸气云爆炸的影响

为了了解障碍物排列方式对海洋平台蒸气云爆炸的影响,基于CFD方法建立蒸气云爆炸计算模型,选用国外MERGE项目的系列爆炸实验进行模型验证,提出用于衡量障碍物排列不均匀度的量化参数,针对海洋平台典型结构形式,分析障碍物排列方式对爆炸强度的影响。研究结果表明:蒸气云爆炸后果对于结构排列方式比较敏感,结构障碍物间隔均匀排列的形式造成的爆炸冲击作用最大;在爆炸发展初期阶段,障碍物阻塞程度对超压产生和发展影响更加显著。最后,基于研究结果,给出在海洋平台油气泄漏危险区将管线沿甲板非均匀排列布置等防控建议,为海洋平台蒸气云爆炸安全防控提供理论指导。     

深水水下测试树球阀剪切连续油管性能分析

为研究不同工况、不同结构参数对于深水水下测试树球阀剪切连续油管性能的影响,采用有限元分析软件建立剪切分析模型,对不同工况下剪切过程进行数值模拟,并与试验对比验证分析模型的准确性;结果显示,有限元模型结果与试验结果相对偏差小于5%;油管剪切过程中会出现2个剪切力矩峰值,通过分析不同工况下2个峰值变化规律,发现油管承受拉力越大、球阀剪切速度越小、球阀外径越小剪切过程所需剪切力越小,剪切性能越好。研究结果表明:得到的剪切模型及不同工况下剪切力变化规律,可为水下测试树的设计选型及现场应用提供指导及参考意义。     

气固两相流90°弯管抗冲蚀结构优化

为了提高天然气输送管道90°弯管的耐磨性能,提出了1种三段弯曲式弯管,通过对弯管弯曲段进行三段式改进来减小弯管中二次流的大小,优化弯管内的流场,改善弯管的冲蚀磨损状况。利用COMSOL仿真软件建立三段式弯管模型,并以弯管弯曲段和出口段二次流平均值之和最小为优化目标,在约束条件下凭借COMSOL中的COBYLA优化算法得到了最优管形;用Fluent对优化后的三段式弯管进行冲蚀数值模拟并与一段式弯管的模拟结果进行对比分析。研究结果表明:与一段式90°弯管相比,优化后的三段式弯管流场更加平稳,其弯曲段的二次流强度大幅降低,弯管壁面的冲蚀磨损程度得到较大的改善。     

基于博弈赋权和灰色关联投影的电网综合风险评估方法

为了对风险形式多样化的电网进行全面客观的评估,提出了一种基于博弈赋权和灰色关联投影的电网综合风险评估方法。首先,通过分析现代电网面临的风险因素,从网架结构、运行状态、能源供给3个方面重新构建了风险评估指标体系;其次,基于博弈赋权模型融合指标主观权值与客观权值,最大化消除了单一赋权法造成的权值偏差;然后,通过灰色关联投影模型计算风险指标样本在理想解上的投影,并以风险指标样本对负理想解的优属度来表征电网综合风险大小;最后,通过案例分析验证了所提方法的有效性和正确性。研究所得电网综合风险评估结果具有合理性和可靠性,对电网调度规划决策的形成具有一定的指导作用。     

Effects of environmental parameters on the chestnut gall wasp and its complex of indigenous parasitoids

The chestnut gall wasp (CGW), Dryocosmus kuriphilus, an invasive pest native to China, has caused severe yield and economic losses to chestnut production in Europe since its arrival in 2002. In Southern Italy, the complex of indigenous parasitoids colonizing CGW was monitored between 2013 and 2015, with the aim of estimating the composition of the indigenous parasitoid complex, its ability to control CGW populations, and the interactions of both factors with several measured environmental parameters. We compared results among three differently managed field types. Results showed an increase in the rate of parasitism both when the host population density was lower and in unmanaged chestnut stands with more natural conditions. The percentage of parasitism in galls was related to morphological traits of the galls and to higher seasonal temperatures, which reduced the parasitism intensity because CGW develops earlier under such conditions. The host–parasitoid mortality inside galls varied among sites and was associated mostly with rot fungi during wet spring and summer months. Parasitoid species richness was similar among the study sites, but the proportion of parasitoid species differed between orchards and unmanaged coppice stands. The timing of attack by parasitoids followed a species-specific successional sequence throughout the larva-to-adult life cycle of the CGW. These interactions should be considered in future research on trophic relationships and when modeling invasive scenarios for new pest species.     

Parental care compromises feeding in the pumpkinseed (<Emphasis Type="Italic">Lepomis gibbosus</Emphasis>)

Providing parental care is potentially costly. Costs can arise through elevated energy expenditure or from an increased risk of mortality. A cost of parental care can also occur because a parent is compromised in their ability to forage. We used pumpkinseed Lepomis gibbosus, a fish with an alternative male mating strategy, to test whether parental males differed in their feeding in comparison with females and cuckolder males. To address this question, we examined the stomach contents of female, cuckolder male, and parental male pumpkinseed during the breeding season over an entire diel cycle. We showed that parental males had a lower total weight of food in their stomachs in comparison with females, while cuckolder males did not. Parental males also had a lower weight and number of chironomids in their stomachs. The temporal pattern of feeding of parental males diverged from that of females, and they had a lower probability of pupal chironomids in their stomachs, which implies spatial segregation in foraging. Parental males had a greater probability of conspecific eggs in their stomachs than females, while the probability of egg cannibalism did not differ between cuckolder males and females. Overall, these finding meet predictions in accordance with an assumption that parental care and territoriality can compromise feeding.     

The fractal dimension of a conspicuous ornament varies with mating status and shows assortative mating in wild red-legged partridges (<Emphasis Type="Italic">Alectoris rufa</Emphasis>)

Complex body designs, such as plumage ornaments in birds, can be described by fractal geometry. These complex patterns could have a role as visual signals during courtship and social interactions, but an empirical validation in the wild is currently lacking. Here, we investigated whether the fractal dimension (FD) of a complex plumage pattern displayed by red-legged partridges Alectoris rufa could function as a potential sexual signal. We captured wild birds early in the breeding season and tested if mated and unmated birds differed in the FD of their conspicuous melanin-based black bib. We also tested if the FD of the black bib was correlated within the pair, looking for evidence of assortative mating based on the expression of this trait. We simultaneously assessed similar effects in other ornamental traits (black bib size, white throat patch and black flank band surface, redness of the eye rings and bill). Mated birds showed higher black bib FD values than unmated ones. Mated males, but not females, also displayed a larger black bib. Moreover, the black bib FD (but not the trait size) and the white throat patch surface showed assortative mating. Finally, females with higher black bib FD showed smaller black flank band surface, suggesting a trade-off in the expression of the two melanin-pigmented plumage traits. This provides unique and novel indication for the shape complexity of a pigmented trait, here described by its fractal dimension, to be potentially under sexual selection in a wild animal.     

The casualties from electric bike and motorized scooter road accidents

Objective: The objective of this study was to describe demographic and injury characteristics of hospitalized injured patients involved in e-bike and motorized scooter accidents at a national level in Israel divided by different road user groups: riders and pedestrians.

Methods: This was a retrospective study based on data from the National Trauma Registry, between January 1, 2013, and December 31, 2015. All hospitalized casualties due to the involvement of an e-bike or motorized scooter were included. The type of hospitalized road user was further categorized and described by different variables.

Results: During the study period, the Israel Trauma Registry identified 795 hospitalized patients due to an e-bike or motorized scooter accident, with a dramatic 6-fold increase from 2013 to 2015. Although the majority of the injured patients were riders, 8% were pedestrians. Among the total casualties, 33% were children aged 0–14 years and among pedestrians 42% were children and 33% were seniors (ages 60+). Five persons died in hospital, 3 riders and 2 pedestrians.

Conclusions: E-bike and motorized scooter riders represent the majority of patients hospitalized due to related traffic incident. This finding questions the social and economic advantages of electric-powered 2-wheeled vehicles.     

我国水资源可持续利用对策

根据可持续发展思想,本文剖析了我国水资源的特点和面临的问题,提出了实现我国水资源可持续利用的对策     

云山国家森林公园旅游开发可行性研究

本文在充分调查的基础上,全面阐述了湘西南云山国家森林公园旅游开发的优越条件,指出了在旅游开发中存在的问题,提出了可行性开发的建议与初步设想,并对开发的前景意义进行了研究分析