Dark induced reproductive inhibition of Daphnia carinata during the 1995 solar eclipse

Population of Daphnia carinata exposed to different times on the day showed sharp inhibition of reproduction (measured different life table data) on the day of solar eclipse as compared to pre- and post-eclipse days. Sudden fall of water temperature and abrupt change to darkness as prevailed during the solar eclipse were responsible for inhibition of reproduction in Daphnia carinata. Cold and dark induced reproductive inhibition was also confirmed in a simulated experiment mimicing eclipse reduction in light and temperature.     

What Determines the Distribution of Coastal Hydrobiid Mudsnails Within North-Western Europe?

The three north-west European species of Hydrobia are often partially segregated along salinity gradients and/or sympatric in the nontidal eastern Danish waters and Baltic Sea, but are rarely sympatric and are confined either to nontidal coastal lagoons ( Hydrobia ventrosa and Hydrobia neglecta ) or to the marine/estuarine intertidal zone ( Hydrobia ulvae ) along the macrotidal Atlantic and North Sea coasts. Significant interspecific competition has been found in Danish waters but not elsewhere in the Atlantic and North-Sea Europe. The two nontidal species and H. ulvae also possess contrasting reproductive strategies. The roles of life-history strategy, interspecific competition and between-habitat dispersal in restricting these mudsnails to their differing habitats are evaluated in the light of these and other findings. It is concluded that all are likely to be relevant, especially dispersal in maintaining and interspecific competition in opposing, mixed populations in the Kattegat-Baltic, and life-history strategy in maintaining the lagoonal versus intertidal dichotomy in the rest of north-west Europe. This dichotomy prevents segregation of species along common salinity gradients outside the Baltic region and restricts potential interspecific competition to within lagoons, where H. ulvae is at a recruitment disadvantage.     

Reliability Analysis of Ice-Induced Fatigue and Damage in Offshore Engineering Structures

—In Bohai Gulf,offshore and other installations have collapsed by sea ice due to the fatigueand fracture of the main supporting components in the ice environments.In this paper presented are someresults on fatigue reliability of these structures in the Gulf by investigating the distributions of iceparameters such as its floating direction and speed,sheet thickness,compressive strength,ice forces on thestructures,and hot spot stress in the structure.The low temperature,ice breaking modes and componentfatigue failure modes are also taken into account in the analysis of the fatigue reliability of the offshorestructures experiencing both random ice loading and low temperatures.The results could be applied to thedesign and operation of offshore platforms in the Bohai Gulf.     

Microalgae and Clean Technologies: A Review

The search for clean technologies needs to be continued to offer alternatives for achieving sustainable energy production and a sustainable economy. This concern is particularly related to the demands of both producing enough renewable energy to meet future needs and reducing greenhouse gas (GHG) emissions. Microalgae are recognized for several benefits they offer, and in recent years, the use of life cycle assessment (LCA) to evaluate the benefits resulting from microalgae cultivation, harvesting/dewatering, biomass drying, extraction, and byproduct development has stimulated research in this area. Considering the importance of microalgae and clean technologies and the increasing number of publications on these subjects, this review aims to perform bibliometric mapping of such studies from 2008 to 2018. Web of Science and Scopus databases are used to identify leading trends. Visualization of similarities viewer (VOSviewer) software is applied to analyze the interactions among keywords. The results of this study indicate an association of microalgae and clean technologies and demonstrate that LCA is one of the most common tools used for such analyses. Bibliometric mapping provides relevant data to reinforce this association and understand the main bottlenecks that must be overcome in this field for future progress to be made.     

Earthquake‐induced loss assessment of steel frame buildings with special moment frames designed in highly seismic regions

This paper discusses an analytical study that quantifies the expected earthquake‐induced losses in typical office steel frame buildings designed with perimeter special moment frames in highly seismic regions. It is shown that for seismic events associated with low probabilities of occurrence, losses due to demolition and collapse may be significantly overestimated when the expected loss computations are based on analytical models that ignore the composite beam effects and the interior gravity framing system of a steel frame building. For frequently occurring seismic events building losses are dominated by non‐structural content repairs. In this case, the choice of the analytical model representation of the steel frame building becomes less important. Losses due to demolition and collapse in steel frame buildings with special moment frames designed with strong‐column/weak‐beam ratio larger than 2.0 are reduced by a factor of two compared with those in the same frames designed with a strong‐column/weak‐beam ratio larger than 1.0 as recommended in ANSI/AISC‐341‐10. The expected annual losses (EALs) of steel frame buildings with SMFs vary from 0.38% to 0.74% over the building life expectancy. The EALs are dominated by repairs of acceleration‐sensitive non‐structural content followed by repairs of drift‐sensitive non‐structural components. It is found that the effect of strong‐column/weak‐beam ratio on EALs is negligible. This is not the case when the present value of life‐cycle costs is selected as a loss‐metric. It is advisable to employ a combination of loss‐metrics to assess the earthquake‐induced losses in steel frame buildings with special moment frames depending on the seismic performance level of interest. Copyright © 2017 John Wiley & Sons, Ltd.     

基于交通振动环境下建筑结构损伤机理及减振隔振的研究现状

随着交通建设的发展,越来越多的公路要临近已有建筑物通过,而由于建设或重车通行引起的振动对周边建筑结构产生了很大的安全威胁,严重的甚至造成了建筑结构的损坏.论文通过对交通振动下建筑结构的振动控制标准和在振动中的损伤机理进行综述,系统总结了交通振动对建筑影响的方法,介绍了目前交通振动对建筑结构安全性影响的研究现状和方法,分...     

受静载荷的岩石在周期载荷作用下破坏的试验研究

为了研究受静载荷的岩石在周期载荷作用下破坏及变形发展规律,在Instron电液伺服材料试验机上进行了红砂岩的单轴动静组合加载试验。采用自制的一维水平静压加载装置,配合Instron电液伺服材料试验机进行了红砂岩的二维动静组合加载试验。试验表明,受静载荷的红砂岩在周期载荷作用下的破坏形态因所受静载荷的状态不同而不同,在周期载荷作用下的应力-应变曲线表现为滞回圈先疏后密再疏,直至破坏;相同条件的受静载荷的红砂岩受不同周期载荷作用时,尽管其应力-应变曲线表现为不同的滞回圈数和不同的全应变,但仍与岩石在周期荷载作用下疲劳破坏的极限变形规律一致,并且破坏岩石所消耗的有效全应变能有向相同值发展的趋势。     

贵州省关岭县土地利用/土地覆被变化及土壤侵蚀效应研究

以贵州省关岭县为例,利用1987和1999年两个时段TM影象和相关资料,分析研究区12年间的土地利用/土地覆被变化及其土壤侵蚀风险。发现:(1)研究区土地利用动态变化较大,年均土地利用综合动态指数为1.36%;(2)旱地和草地互相转化比例高,草地开垦为旱地和旱地弃耕为草地的动态变化幅度远远超过旱地和草地最终面积变化的幅度;(3)山区土地利用的空间变化主要体现在垂直方向;(4)研究区裸土面积下降,一部分被植被覆盖,另一部分由于土壤流失殆尽,形成裸露基岩,故植被覆盖率和基岩出露率上升;(5)石漠化程度加剧,其中旱地石漠化发展速度最快;(6)土壤侵蚀形势严峻。     

Potential of EPR imaging to detect traces of primitive life in sedimentary rocks

In the prospect of the search for traces of primitive life on Earth and Mars, we investigated the possibility to detect and visualize the spatial distribution of minute amounts of organic matter in ancient rocks, in a non-destructive way, by Electron Paramagnetic Resonance Imaging (EPRI). We studied a series of non- or moderately metamorphosed siliceous rocks (cherts) of different ages ranging from 45 Ma to 3490 Ma and embedding fossile organic matter. In the case of the oldest cherts containing only mature insoluble organic matter (IOM), with IOM^• radicals characterized by a single Electron Paramagnetic Resonance (EPR) line, we could obtain three-dimensional images with sub-millimetric resolution of the organic matter distribution inside samples containing as low as 10¹⁴–10¹⁵ radicals per gram. In the case of younger cherts, containing less mature organic matter, and thus several types of organic radicals, we showed that selective imaging of each type of radical was possible provided that the EPR spectra did not overlap. Selective imaging of either the organic radicals or of the oxygen vacancy (E' centres) of the mineral matrix, which are ubiquitous in siliceous rocks, was possible, selecting either one or the other paramagnetic species with high power in-phase, 1st harmonic detection or with 90°-out-of-phase, 2nd harmonic detection of the EPR. The influence of ferromagnetic inclusions in the mineral matrix on the EPRI of the organic matter was also addressed. Image artifacts due to the ferromagnetic resonance signal of these inclusions could be easily removed by background substraction from the EPR spectra before image reconstruction. We thus showed that selective imaging by EPR of minute amounts of fossile organic matter in ancient rocks could be possible despite the magnetic complexity of such materials.     

海洋平台结构的最新研究进展 第9届ISOPE大会报告综述

分9个专题对第9届ISOPE大会报告有关海洋平台结构的最新研究动态进行了评述和总结,并结合我国海洋石油工业的发展现状提出了一些建议,供我国产业部门和有关高校与研究机构参考。