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171.
为研究近场地震作用下库区深水钢筋混凝土高墩的概率损伤特性,以90 m高的矩形空心薄壁钢筋混凝土深水高墩为研究对象,综合考虑桥墩设计参数和近场地震动的随机性,基于OpenSees软件建立深水高墩有限元模型,开展不同水深的7种工况(水深:0、15、30、45、60、75、90 m)下,顺桥向和横桥向近场地震激励的增量动力非线性分析。以截面临界曲率值为损伤指标,研究深水高墩的易损性。结果表明:各工况下,轻微损伤、中等损伤和严重损伤阶段的损伤概率均随地震波峰值加速度的增加而增大,并且当峰值加速度达到1.0g时损伤概率达到最大,而完全损伤阶段的损伤概率则在峰值加速度为0.5g时出现峰值点;近场地震顺桥向激励时,墩身中上部和墩底区域均较容易损伤,而横桥向激励时仅墩底区域较容易损伤;当水深超过45 m后,高墩最大损伤概率变化不大且截面曲率概率需求基本一致,45 m水深为深水高墩显著水深。因此,应重点分析水深达到高墩高度一半时深水高墩的损伤情况。 相似文献
172.
杜艳华 《中国环境管理干部学院学报》2013,(5):69-71
冷轧废乳化液是轧钢过程中排放的高浓度难降解废水,治理的关键是破乳技术。主要介绍了混凝工艺、膜分离工艺、电凝聚气浮工艺、Fenton氧化工艺、微电解工艺、微波破乳工艺原理及研究现状,并对每种工艺在乳化液废水破乳中的优缺点进行了阐述。其中混凝破乳和膜分离破乳是目前应用最广泛的技术,其他技术由于运行管理以及成本的原因应用相对较少,今后破乳技术的发展应该是高效、低成本的新技术开发或者对原有破乳技术进行革新。 相似文献
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175.
Abstract Ecological footprint (EF) has received considerable attention as a useful indicator in the context of sustainable development. So far, EF has been used in numerous studies by academies, organizations and government authorities. However, the results of these studies failed to be comparable directly with each other due to imprecise data sets, unmodified accounting methods of pasture and fossil energy, ignored secondary products, undefined process of calculating yield factors and improper biocapacity for biodiversity. In this paper, we elaborated on EF estimating methods from six categories of consumption in order to overcome the limitations above. We adopted precise data and revised methods, calculated EF of some secondary products, introduced weighted factor to calculate yield factors and adjusted biocapacity by an appropriate amount. Meanwhile, we investigated the resource consumption of Liaoning Province in 2006 to assess EF. Its results showed that Liaoning Province overused its natural capital and was in an unsustainable state. We concluded that two specific problems that had arisen in EF assessment and gave some suggestions for Liaoning Province to improve its unsustainable state. 相似文献
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177.
以可持续发展相关理论为基础,利用系统工程的理论和方法建立了河北省县域可持续发展指标体系及其评价标准,并在全省范围应用,对全省136个县(市)可持续发展能力做出了评价。结合评价结果,阐述了河北省县域可持续发展能力的特征,提出了河北省县域可持续发展的方向和思路。 相似文献
178.
Jiansu Mao Yanchun Du Linyu Xu Yong Zeng 《Frontiers of Environmental Science & Engineering》2011,5(4):585-596
Improving eco-efficiency is propitious for saving resources and reducing emissions, and has become a popular route to sustainable development. We define two energy-related eco-efficiencies: energy efficiency (ENE) and greenhouse gas (GHG) emission-related eco-efficiency (GEE) using energy consumption and the associated GHG emissions as the environmental impacts. Using statistical data, we analyze China??s energy consumption and GHG emissions by industrial subsystem and sector, and estimate the ENE and GEE values for China in 2007 as 4.871×107 US$/PJ and 4.26×108 US$/TgCO2eq, respectively. Industry is the primary contributing subsystem of China??s economy, contributing 45.2% to the total economic production, using 79.6% of the energy consumed, and generating 91.4% of the total GHG emissions. We distinguish the individual contributions of the 39 industrial sectors to the national economy, overall energy consumption, and GHG emissions, and estimate their energyrelated eco-efficiencies. The results show that although ferrous metal production contributes only 3.5% to the national industrial economy, it consumes the most industrial energy (20% of total), contributes 16% to the total industrial global warming potential (GWP), and ranks third in GHG emissions. The power and heat sector ranks first in GHG emissions and contributes one-third of the total industrial GWP, although it only consumes about 8% of total industrial energy and, like ferrous metal production, contributes 3.5% to the national economy. The ENE of the ferrous metal and power and heat sectors are only 8 and 2.1×107 US$/PJ, while the GEE for these two sectors are 9 and 4×104 US$/GgCO2eq, respectively; these are nearly the lowest ENE and GEE values among all 39 industry sectors. Finally, we discuss the possibility of ecoefficiency improvement through a comparison with other countries. 相似文献
179.
Assessment of spatial distribution of soil loss over the upper basin of Miyun reservoir in China based on RS and GIS techniques 总被引:2,自引:0,他引:2
Chen T Niu RQ Wang Y Li PX Zhang LP Du B 《Environmental monitoring and assessment》2011,179(1-4):605-617
Soil conservation planning often requires estimates of the spatial distribution of soil erosion at a catchment or regional scale. This paper applied the Revised Universal Soil Loss Equation (RUSLE) to investigate the spatial distribution of annual soil loss over the upper basin of Miyun reservoir in China. Among the soil erosion factors, which are rainfall erosivity (R), soil erodibility (K), slope length (L), slope steepness (S), vegetation cover (C), and support practice factor (P), the vegetative cover or C factor, which represents the effects of vegetation canopy and ground covers in reducing soil loss, has been one of the most difficult to estimate over broad geographic areas. In this paper, the C factor was estimated based on back propagation neural network and the results were compared with the values measured in the field. The correlation coefficient (r) obtained was 0.929. Then the C factor and the other factors were used as the input to RUSLE model. By integrating the six factor maps in geographical information system (GIS) through pixel-based computing, the spatial distribution of soil loss over the upper basin of Miyun reservoir was obtained. The results showed that the annual average soil loss for the upper basin of Miyun reservoir was 9.86 t ha(-1) ya(-1) in 2005, and the area of 46.61 km(2) (0.3%) experiences extremely severe erosion risk, which needs suitable conservation measures to be adopted on a priority basis. The spatial distribution of erosion risk classes was 66.9% very low, 21.89% low, 6.18% moderate, 2.89% severe, and 1.84% very severe. Thus, by using RUSLE in a GIS environment, the spatial distribution of water erosion can be obtained and the regions which susceptible to water erosion and need immediate soil conservation planning and application over the upper watershed of Miyun reservoir in China can be identified. 相似文献
180.
中国民航维修系统正在建立安全管理体系,本文介绍了风险管理目的、构建原则并举例说明风险管理的实施步骤。为中国民航维修系统建立风险管理进行了有益的探索。 相似文献