循环荷载作用下三明治形加筋土挡墙的模型试验与数值模拟∗

为研究循环荷载作用下三明治形加筋土挡墙的受力特性,进行了一系列砂土加筋土挡墙和三明治形加筋土挡墙的动加载室内模型试验.针对不同的加载特征,分析加筋土挡墙的变形和应力响应.采用FLAC3D建立三明治形加筋土挡墙的数值计算模型,通过与模型试验的对比,验证了计算模型的可靠性,分析了循环荷载下挡墙的变形、加速度和潜在破裂面.研究结果表明:三明治形加筋土挡墙变形与竖向土压力随荷载幅值、荷载频率和激振器个数的增加而增大;荷载对土压力的影响随距振源距离的增大而减小;相同加载条件下,三明治形挡墙的顶部沉降更大;随着挡墙高度的增加,土压力的振动幅值逐渐增大,土压力峰值减小;挡墙沉降并非成层均匀沉降,内部分层沉降出现双峰值;随墙高减小加速度衰减,加速度峰值在挡墙上部的平均衰减率最大;三明治形加筋土挡墙与砂土加筋土挡墙破裂面位置相近.地面交通荷载引起的振动对挡墙结构产生不利影响是加筋挡墙的研究重点.     

Detection and Characterization of Avastrovirus Associated with Diarrhea Isolated from Minks in China

Astroviruses are becoming a growing concern in veterinary and public health. Many astrovirus species are associated with enteric diseases have been described in both mammalian and avian hosts. In the present study, 23 fecal samples from diarrheic minks were collected in Liaoning and Shandong Province, and an investigation of astrovirus was performed using biochemical methods and RT-PCR assay with specific primers. A total of four mink astroviral isolates were detected from sick minks with diarrhea problems. Further sequencing and characterization of the partial ORF1b gene and ORF2 gene segments revealed low sequence identities (20.0–85.3 and 31.8–87.2 %) with known astroviral strains, indicating the emergence of a novel clade of astroviruses. Some new features of the astroviral genome have also been discovered. The phylogenetic tree revealed that all samples were distantly related to mink astrovirus and were closely related to chicken astroviruses and turkey astroviruses. MK/DL-1, MK/DL-2, MK/SD-1, and MK/SD-2 formed a new clade and were found to be more closely related to astroviruses from birds than to other mink strains, indicating past cross-species transmission and considerable zoonotic potential.     

油田含油污水生化处理技术研究及应用

国内油田在原油生产过程中的产出污水,大部分经过处理后作为水驱采油的水源,部分多余的水经过适当处理后排放,对油田周边环境造成污染.1998年国务院颁布了<关于环境保护若干问题的决定>,决定要求,2000年以前,全国所有工业污染源必须达到国家或地方规定的排放标准.     

Monitoring seasonal distribution of an endangered anadromous sturgeon in a large river using environmental DNA

Monitoring dynamic distribution is crucial to conservation management of anadromous sturgeons, but traditional survey methods are less efficient for low-density populations in a large river. Natural propagation of Chinese sturgeon has been monitored annually mainly at the spawning ground using netting for eggs and hydroacoustics for broodstock. However, absence of spawning was observed sporadically in recent years, indicating further crises for the declining population. We analyzed eDNA of water samples collected from 24 sites across 1360 km of the migratory route of anadromous Chinese sturgeon in the middle and lower reaches of the Yangtze River. Chinese sturgeon was detected at 9 sites during the spawning season and 14 sites after the spawning season. We found that positive eDNA detection rates remained constant in the middle reaches but dramatically changed in the lower reaches, reflecting seasonal migration pattern of Chinese sturgeon. Invasive sturgeons were detected in the river, indicating their possible escape from aquaculture facilities. This study established a protocol for the use of eDNA to monitor distribution of Chinese sturgeon and could be valuable in making better policies for the conservation of this endangered species.     

遥感旱灾模型综合分析

本文在野外实验的基础上，对遥感旱灾模型进行综合分析和评价。运用四年的实地观测数据，校正了旱灾模型中的待定系数，使其能用于ＮＯＡＡ气象卫星对旱情的监测。对复杂的蒸散模型简化的可行性进行了尝试性研究。     

轻轨交通噪声分析和控制对策

在参阅大量国内外技术资料基础上，通过轻轨交通噪声的来源、特征等系统的分析和总结，对其控制对策尤其是声屏障技术的现状和发展进行了探讨，为我国轻轨交通噪声的研究分析和控制防治提供一定借鉴。     

赤潮的预测与控制对策

近年来,我国沿海地区越来越频繁的赤潮对水域环境与海水养殖业等造成了严重破坏。本文从赤潮发生的条件入手,分析了赤潮的预测方法,并提出了相应的对策。     

酒钢焦化厂焦炉地下室通风降温技术改造探讨

介绍了酒钢焦化厂焦炉地下室通风降温技术改造成果。通过参数确定、方案对比,采用了通风降温技术措施,效桌明显,改善了职工的作业环境,保护了工人的身体健康。     

环境减灾防灾的一个重大课题─—雷暴和防雷技术

本文在阐明雷暴形成的背景条件的基础上，提供了全球雷暴的分布特征，分析其对环境造成的严重危害，并着重分析雷电在雷暴中的形成及其危害．最后简略介绍防雷电技术近３０年来的进展．     

二氧化硫对棉花叶片光谱反射特性的影响

在动态熏气箱中对棉株进行SO_2处理(2ppm,8小时).测定叶片光谱反射率和微分光谱.受SO_2伤害的棉叶光谱反射率发生变化:在可见光部分,反射率普遍增加;在近红外部分,反射率降低.整个光谱反射曲线发生蓝移,初步确定几个波段可用于区别污染的与正常的棉叶光谱反射特性.