基于有限元法的土坯民房地震响应分析研究

基于有限元法研究了土坯民房的地震响应特征,提出了实施土坯民房震害防治的对策性建议。地震动由结构底部向上传播时,低频部分被墙体吸收,水平加速度逐渐增大,揭示了低破坏性地震动损伤土坯民房屋盖系统、高破坏性地震动损坏土坯民房承重构件,进而导致整体结构损毁的动力机制。砖柱(木柱)承重土坯民房的地震响应大于墙体承重土坯民房,后者最大剪应力集中在中间开间的横墙和纵墙的连接处,最大主应力集中在中间开间的横墙上;前者最大剪应力集中在横墙和柱的连接处,最大主应力集中在中间开间的柱体上部。由于2种结构类型土坯民房的薄弱环节有所不同,地震时的致灾原因亦存在差异。     

国内外数字化应急预案技术发展现状与趋势

简述了数字化预案的概念、功能和主要开发步骤;分析了数字化预案发展的三个阶段,即电子化、可视化和智能化;通过国内外数字化预案项目典型案例,分析了国内外数字化预案技术的发展现状与趋势,以期为我国数字化预案技术发展做出有益的探讨。     

应急预案体系研究

基于社会和经济迅速发展需要以及各类公共突发事件频发的现实,国家全面加强应急管理体系建设工作,应急预案体系建设是应急管理体系建设的重要内容。文章反思了应急预案编制和应急预案体系建设实践过程中的一些混乱和偏差,指出了应急预案体系建设方面面临的一些主要问题与困难;以系统理论为基础,从基础概念出发分析了应急预案体系各要素的内涵,理清了各要素之间的相互关系;提出了一种应急预案体系的基本模型及其扩展方法,为应急预案体系建设寻求理论依据。另外,文章还在应急预案体系研究和实践的方法论方面进行了一些思考和探索。其研究成果可为应急与安全领域研究、应急预案体系建设实践提供一些有益的理论参考。     

冲击环境后峰锯齿脉冲试验条件自动寻优方法

目的 通过自动寻优制定冲击环境后峰锯齿脉冲试验条件,避免冲击“过试验”。方法 根据冲击响应谱的基本原理和谱型特征,提出利用对数距离量化评价2条谱型的吻合度。对冲击环境和后峰锯齿脉冲分别进行冲击响应谱分析,将2条冲击响应谱之间的对数距离最小作为优化目标,将后峰锯齿脉冲的波形参数作为优化参数,基于自适应差分进化算法,提出冲击环境后峰锯齿脉冲试验条件自动寻优方法。结果 将所提方法分别应用于模拟冲击环境和实测冲击环境,均获得了合理的后峰锯齿脉冲试验条件,验证了所提方法的正确性。结论 提出的基于自适应差分进化算法的冲击环境后峰锯齿脉冲试验条件自动寻优方法正确可行。     

Optimization of carbon dioxide absorption in a continuous bubble column reactor using response surface methodology

Carbon dioxide absorption using amine based solvents is a well-known approach for carbon dioxide removal. Especially with the increasing concerns about greenhouse gas emissions, there is a need for an optimization approach capable of multifactor calibration and prediction of interactions. Since conventional methods based on empirical relations are not efficiently applicable, this study investigates use of Response Surface Methodology as a strong optimization tool. A bubble column reactor was used and the effect of solvent concentration (10.0, 20.0 and 30.0 vol%), flow rate (4.0, 5.0 and 6.0 L min⁻¹), diffuser pore size (0.5, 1.0 and 1.5 mm) and temperature (20.0, 25.0 and 30.0°C) on the absorption capacity and also overall mass transfer coefficient was evaluated. The optimization results for maintaining maximum capacity and overall mass transfer coefficient revealed that different optimization targets led to different tuned operational factors. Overall mass transfer coefficient decreased to 34.7 min⁻¹ when the maximum capacity was the desired target. High reaction rate along with the highest absorption capacity was set as desirable two factor target in this application. As a result, a third scenario was designed to maximize both mass transfer coefficient and absorption capacity simultaneously. The optimized condition was achieved when a gas flow rate of 5.9 L min⁻¹, MEA solution of 29.6 vol%, diffuser pore size of 0.5 mm and temperature of 20.6°C was adjusted. At this condition, mass transfer coefficient reached a maximum of 38.4 min⁻¹, with a forecasted achievable absorption capacity of 120.5 g CO₂ per kg MEA.     

Modelling the impact of flooding stress on the growth performance of woody species using fuzzy logic

Among the driving processes responsible for riparian forest dynamics the species-specific impact of flooding on the development of woody plants plays a key role—particularly for lowland rivers. Only a few of the forest succession models currently in use incorporate the flooding stress response of trees. This situation is mainly due to the incomplete investigation of the flooding tolerance processes and the related abiotic and biotic factors. In an attempt to use the wide-ranging but still rather vague knowledge available on flooding stress, the research presented in this paper proposes an approach to model tree response to flooding using the fuzzy set theory. The model is illustrated for the case of central European species. Flooding stress response to the abiotic factors of duration, depth and frequency of flooding differs according to five flooding tolerance classes and is expressed by means of a growth factor that limits optimal tree growth. We show that existing fuzzy set theory is able to generate and calibrate a flood stress response model which in turn can be incorporated into more complex forest succession models adapted to riparian areas.     

Benefit of suites of defensive behavior induced by predator chemical cues on anuran tadpoles, Hyla japonica

When predator chemical cues are present, low activity of prey is a commonly seen defensive behavior. However, few studies have explored the functional implications of the defensive behaviors and, thus, elucidated the possible linkages between behavioral responses and its consequences. In this study, we experimentally investigated how behavioral responses of Hyla japonica tadpoles to predator chemical cues affect vulnerability to a dragonfly nymph Anax parthenope julius. The frequency of tadpoles attacked by dragonfly nymphs was lower with chemical cues of predator was present than without chemical cues, and most of attacks occurred when tadpoles were mobile. When tadpoles were exposed to chemical cues, on the other hand, their swimming speed was quicker and swimming distance was longer, respectively, and the rates of being approached of the swimming tadpoles by dragonfly nymph was lower than those not exposed to chemical cues. We found that the tadpoles are induced by predator chemical cues not only to generally lower activity but also to swim in bursts as additional behavior and that the suite of their behavioral responses reduce the vulnerability against dragonfly nymph. Tadpoles can receive information about the predation risks by chemical cues and adjust their defensive behavior accordingly.     

黄河上游牧草区水热变化及土壤水分响应

利用月降水、气温等资料,分析甘南草原地区水热配置和土壤水分变化。结果表明:牧草生长期降水增多,成熟期降水减少;逐月降水、气温变化的线性趋势有明显差异;月降水明显减少和气温明显上升中存在突变,周期谱有明显差别。土壤水分存在显著下降趋势,在1995年发生了突变(转向明显负距平)。土壤水分年际演变与降水同向性较好,年代际变化与气温呈反位相配置;土壤水分演变振荡周期对降水短周期和气温长周期响应明显。     

喷射火环境下石化管廊管道失效特征试验研究

为探究喷射火灾下石化管廊管道热力学响应特征,依据流体力学相似理论搭建缩比试验平台,开展石化管廊管道热力学响应试验研究.通过分析火灾中管道热力学响应特征及事故多米诺演化特征,探讨各因素对管道升温和失效的影响程度,并结合强度理论建立管道失效时间定量计算模型.研究结果表明:火灾功率是管道失效的主导因素,随着火灾功率的增大,管...     

钛酸锂电池在绝热环境中循环的热响应特性

钛酸锂电池广泛应用于储能系统,其安全性也备受关注。采用加速量热仪与电池循环仪联用技术,对钛酸锂电池在循环过程中的热响应情况进行了研究。研究表明,测试电池在放电和充电阶段均有明显的小幅度温升现象。通过测试电池在不同倍率下的产热情况,发现电池在各循环阶段的绝热产热量与循环倍率成正比,其热失控危险性也随着循环倍率的增大而增加。