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71.
Jifeng Hou Lijuan Zhao Weizhen Liu Yanxu Zhang 《International Journal of Green Energy》2020,17(8):501-509
ABSTRACT Aiming at backfill with crack under the thermo-mechanical (TM) coupling, the concepts of crack macro-damage, loading meso-damage, thermal meso-damage, and total damage of backfill were proposed. Based on the statistical damage theory, considering the coupling effects of temperature, load and initial crack, a damage evolution model of backfill with crack under TM coupling effects was established. Based on this, the strength criterion of backfill with crack considering the effects of thermal and mechanical coupling was constructed by multivariate function full differential method. The research shows that: (1) The theoretical curves of damage evolution model and strength criterion of backfill with crack under TM coupling are in good agreement with the test curves, which verifies the rationality of the model. (2) The initial thermal damage decreases first and then increases with increasing temperature, reaches a minimum value at 40°C, and generally shows a “V” -shaped distribution law. The coupling effect of temperature and crack aggravates the total damage of the backfill. (3) The strength criterion can reflect the relationship between the stress and strain of each limit state and the parameters of backfill with crack under different temperature conditions and can provide a certain reference for the evaluation of the stability of backfill with geological defects such as joints and crack in deep high temperature mines. 相似文献
72.
综述了国内外危险化学品分类体系,以苯乙烯为例,参考欧盟SEBC体系,建立了危险化学品海洋环境应急监测信息卡,内容包括分类、索引号及纳入名录,理化性质及行为特征判断,健康危害及防护要求,检测方法及评价标准等4类信息。建议进一步筛选海洋污染事故涉及的典型或高危化学品,细化SEBC体系,加强快速检测技术研究,构建适应我国海洋环境应急监测需求的危险化学品分类体系和数据库。 相似文献
73.
为探索木材在热流变化时的着火特点并提出着火判据,通过试验研究了木材在线性增长热流条件下的自发着火性能,测定了泡桐、椿木、榆木和刺槐4种木材的点燃时间、木材表面的入射热流以及试样内部的温度.结果表明.当热流增长率大于等于0.199kw/(m~2·s)时,试验的所有木材均可以被点燃,点燃这些木材的临界热流增长率介于0.065~0.103 kw/(m~2·s).建立了木材着火的计算模型,计算得出木材自发着火时的表面温度约为500℃.根据试验和计算的结果提出了-结合表面温度和临界热流增长率的木材自发着火复合判据. 相似文献
74.
Jae H. Ryu Richard N. Palmer Sangman Jeong Joo Heon Lee Young‐Oh Kim 《Journal of the American Water Resources Association》2009,45(2):485-499
Abstract: A decision support system for sustainable water resources management in a water conflict resolution framework is developed to identify and evaluate a range of acceptable alternatives for the Geum River Basin in Korea and to facilitate strategies that will result in sustainable water resource management. Working with stakeholders in a “shared vision modeling” framework, sustainable management strategies are created to illustrate system tradeoffs as well as long‐term system planning. A multi‐criterion decision‐making (MCDM) approach using subjective scales is utilized to evaluate the complex water resource allocation and management tradeoffs between stakeholders and system objectives. The procedures used in this study include the development of a “shared vision model,” a simulated decision‐making support system (as a tool for sustainable water management strategies associated with water conflicts, management options, and planning criteria), and the application of MCDM techniques for evaluating alternatives provided by the model. The research results demonstrate the utility of the sustainable water resource management model in aid of MCDM techniques in facilitating flexibility during initial stages of alternative identification and evaluation in a basin suffering from severe water conflicts. 相似文献
75.
新疆地处中国西北典型干旱内陆区,生态环境比较恶劣,建立适合新疆的省区一级生态环境质量综合评价指标体系,将对科学、客观了解新疆乃至整个西北干旱区生态环境状况都具有十分重要的理论和实践意义。采用综合指数法,从降水量、植被指数、生态功能价值、土壤侵蚀、降尘量、悬浮物等6个方面选取指标,分别以景观单元和县市为评价单元,建立了简易合理、具可操作性的不同尺度的新疆生态环境质量评价指标体系,并确定了各指标的权值和相对的分级标准,为新疆生态环境现状的准确评价提供了可靠依据,对新疆社会经济的可持续发展和生态环境管理将起到积极作用。 相似文献
76.
影响大型复杂机械钢结构系统可靠性的因素分析 总被引:2,自引:0,他引:2
以结构力学为理论依据,以有限单元法为基础,借助和参考有关有限元程序设计方法,按照结构系统可靠性失效模式分析的要求,采用编程语言研制成功基于有限元的可靠性分析软件RAPS(Reliability Analysis Program of Structure based on FEM),运用该软件对立体车库钢结构的可靠性进行具体的分析;对判定结构系统失效与否的失效准则进行讨论和分析,并针对立体车库钢结构,得出合理的失效准则和系统可靠度的计算方法;通过实例说明约界参数CAP、失效路径长度和系统复杂程度对失效准则和系统可靠度结果的影响。 相似文献
77.
78.
Little is known on the factors controlling distribution and abundance of snow petrels in Antarctica. Studying habitat selection through modeling may provide useful information on the relationships between this species and its environment, especially relevant in a climate change context, where habitat availability may change. Validating the predictive capability of habitat selection models with independent data is a vital step in assessing the performance of such models and their potential for predicting species’ distribution in poorly documented areas.From the results of ground surveys conducted in the Casey region (2002–2003, Wilkes Land, East Antarctica), habitat selection models based on a dataset of 4000 nests were created to predict the nesting distribution of snow petrels as a function of topography and substrate. In this study, the Casey models were tested at Mawson, 3800 km away from Casey. The location and characteristics of approximately 7700 snow petrel nests were collected during ground surveys (Summer 2004–2005). Using GIS, predictive maps of nest distribution were produced for the Mawson region with the models derived from the Casey datasets and predictions were compared to the observed data. Models performance was assessed using classification matrixes and Receiver operating characteristic (ROC) curves. Overall correct classification rates for the Casey models varied from 57% to 90%. However, two geomorphologically different sub-regions (coastal islands and inland mountains) were clearly distinguished in terms of habitat selection by Casey model predictions but also by the specific variations in coefficients of terms in new models, derived from the Mawson data sets. Observed variations in the snow petrel aggregations were found to be related to local habitat availability.We discuss the applicability of various types of models (GLM, CT) and investigate the effect of scale on the prediction of snow petrel habitats. While the Casey models created with data collected at the nest scale did not perform well at Mawson due to regional variations in nest micro-characteristics, the predictive performance of models created with data compiled at a coarser scale (habitat units) was satisfactory. Substrate type was the most robust predictor of nest presence between Casey and Mawson. This study demonstrate that it is possible to predict at the large scale the presence of snow petrel nests based on simple predictors such as topography and substrate, which can be obtained from aerial photography. Such methodologies have valuable applications in the management and conservation of this top predator and associated resources and may be applied to other Antarctic, Sub-Antarctic and lower latitudes species and in a variety of habitats. 相似文献
79.
80.
目的对处于多轴应力状态下的复合型裂纹起裂角进行预测。方法考虑材料的弹性性能,利用商业有限元软件ABAQUS中的Seam裂纹模拟穿透型裂纹损伤,建立双轴载荷作用下中心带孔边裂纹板的三维有限元模型,通过位移外推法得到裂纹尖端的应力强度因子(Stress Intensity Factor,SIF),并利用求得的SIF基于最大周向应力断裂准则预测孔边裂纹的起裂角。结果通过与相关文献结果进行对比,发现通过该有限元方法计算得到的应力强度因子与文献结果的最大误差在2%以内,预测的裂纹起裂角与文献结果的最大误差在3%以内。结论该有限元方法计算的裂纹起裂角与文献结果一致,因此文中求解复合型裂纹起裂角所使用的有限元方法是可靠有效的。 相似文献