下沉式广场“准安全区”可行性研究

为研究位于某广场建筑商业综合体裙房中央的下沉式广场作为人员疏散的准安全区的可行性,运用烟气模拟软件FDS得到了可用安全疏散时间ASET,并通过疏散模拟软件Building-Exo-dus和水力模型计算方法得出了所需安全疏散时间RSET。研究表明,人员安全疏散条件ASET相似文献   

浮顶储罐导电片间隙放电危险性研究

储罐在实际运行中,受浮盘的上下移动、机械应力、老化、油污、金属腐蚀等因素的影响,很难确保导电片与罐壁紧密贴合,容易形成微小间隙,在这种情况下遭受雷击易产生间隙放电,出现打火现象.为了分析导电片与储罐罐壁导电片产生间隙放电的危险性,根据Townsend气体放电理论计算了导电片和储罐罐壁间的击穿电压,采用1.2/50μs冲击电压波开展了导电片间隙放电实验,分析了导电片击穿电压与空气间隙距离的关系.结果证明:当导电片和罐壁贴合不良时,导电片和罐壁之间极易产生火花放电;当空气间隙d=0.1cm时,平均空气击穿电压仅为5280V;随着间隙的增大,空气击穿电压也随之增大;导电片间隙放电实验数据与Townsend气体放电理论值吻合.最后,根据以上结论,针对浮顶储罐导电片间隙放电的危险性,提出了改进措施.     

Boosting freshwater fish conservation with high-resolution distribution mapping across a large territory

The lack of high-resolution distribution maps for freshwater species across large extents fundamentally challenges biodiversity conservation worldwide. We devised a simple framework to delineate the distributions of freshwater fishes in a high-resolution drainage map based on stacked species distribution models and expert information. We applied this framework to the entire Chinese freshwater fish fauna (>1600 species) to examine high-resolution biodiversity patterns and reveal potential conflicts between freshwater biodiversity and anthropogenic disturbances. The correlations between spatial patterns of biodiversity facets (species richness, endemicity, and phylogenetic diversity) were all significant (r = 0.43–0.98, p < 0.001). Areas with high values of different biodiversity facets overlapped with anthropogenic disturbances. Existing protected areas (PAs), covering 22% of China's territory, protected 25–29% of fish habitats, 16–23% of species, and 30–31% of priority conservation areas. Moreover, 6–21% of the species were completely unprotected. These results suggest the need for extending the network of PAs to ensure the conservation of China's freshwater fishes and the goods and services they provide. Specifically, middle to low reaches of large rivers and their associated lakes from northeast to southwest China hosted the most diverse species assemblages and thus should be the target of future expansions of the network of PAs. More generally, our framework, which can be used to draw high-resolution freshwater biodiversity maps combining species occurrence data and expert knowledge on species distribution, provides an efficient way to design PAs regardless of the ecosystem, taxonomic group, or region considered.     

Energy flows in the coffee plantations of Costa Rica: from traditional to modern systems (1935–2010)

Regional Environmental Change - This article addresses energy flows in the coffee agro-ecosystems of Costa Rica within the context of the socio-ecological transition, between 1935 and 2010,...     

RF多功能芯片on-wafer评估系统的研究

评估RF多功能芯片在不同环境温度下的性能指标是十分重要的,从分析射频多功能芯片功能和主要性能指标出发,研制了一款自动化芯片在片评估系统。采用上位机进行多种芯片工作状态和设备仪器状态控制,实现了芯片在各种不同工作状态不同温度下的测试数据采集、判断和保存。经实际评估验证,该评估系统能高效高可靠性的完成射频多功能芯片在不同环境温度下的on-wafer级性能评估。     

Application of the Red List Index for conservation assessment of Spanish vascular plants

The International Union for Conservation of Nature (IUCN) Red List Index (RLI) is used to measure trends in extinction risk of species over time. The development of 2 red lists for Spanish vascular flora during the past decade allowed us to apply the IUCN RLI to vascular plants in an area belonging to a global biodiversity hotspot. We used the Spanish Red Lists from 2000 and 2010 to assess changes in level of threat at a national scale and at the subnational scales of Canary Islands, Balearic Islands, and peninsular Spain. We assigned retrospective IUCN categories of threat to 98 species included in the Spanish Red List of 2010 but absent in the Spanish Red List of 2000. In addition, we tested the effect of different random and taxonomic and spatial Spanish samples on the overall RLI value. From 2000 to 2010, the IUCN categories of 768 species changed (10% of Spanish flora), mainly due to improved knowledge (63%), modifications in IUCN criteria (14%), and changes in threat status (12%). All measured national and subnational RLI values decreased during this period, indicating a general decline in the conservation status of the Spanish vascular flora. The Canarian RLI value (0.84) was the lowest, although the fastest deterioration in conservation status occurred on peninsular Spain (from 0.93 in 2000 to 0.92 in 2010). The RLI values based on subsamples of the Spanish Red List were not representative of RLI values for the entire country, which would discourage the use of small areas or small taxonomic samples to assess general trends in the endangerment of national biotas. The role of the RLI in monitoring of changes in biodiversity at the global and regional scales needs further reassessment because additional areas and taxa are necessary to determine whether the index is sufficiently sensitive for use in assessing temporal changes in species’ risk of extinction.     

基于水质水量的城镇污水处理厂工艺运行稳定性研究

采用四川省2座位于不同排水服务区域的城镇污水处理厂的样本数据,统计分析了日处理水量,COD、TN、TP浓度及负荷和C/N、C/P等统计量的累积频率分布规律,并分析了各统计量的分布特征对工艺运行稳定性的影响。结果表明,污水处理厂A进水污染物负荷的累积频率分布范围较大,其采用的周期循环活性污泥(CASS)工艺基本能适应进水水质的随机变化,但因存在碳源随机性不足情况,可能导致其脱氮稳定性降低;污水处理厂B进水污染物负荷的累积频率分布范围较小,虽然其采用的厌氧—缺氧—好氧(A2/O)工艺的调控能力较低,但也基本能适应其服务区域内进水水质的随机变化;2座污水处理厂的日处理水量累积频率分布与污染物浓度及负荷的累积频率分布之间均存在显著的差异,日处理水量的累积频率分布比较集中,而污染物浓度及负荷的累积频率分布的离散范围较大,这也潜在威胁到工艺运行的稳定性。总体来看,2座污水处理厂的处理工艺选择恰当,均能较好适应其服务区域的进水水质和水量的要求。