分层岩土介质爆炸效应的三维仿真模拟

分层岩土介质的爆炸效应是一个复杂的动力学问题,运用离散元框架内的三维梁-颗粒模型模拟分层岩土介质的爆炸效应.把介质用颗粒单元离散化,在相邻颗粒间添加梁,这样研究对象就成为一个由颗粒单元与梁网络形成的复合结构.梁的作用是使颗粒的集合体具有与初始对象近似的强度性质.用离散元法描述颗粒单元的运动,并通过相邻颗粒间的相对位移计算梁的变形,根据梁的强度准则判别梁是否存在;裂纹的产生及碎块的形成通过梁的消失来体现.然后采用矩阵位移法计算梁的受力,并反作用于对应的颗粒单元上.模拟结果表明,梁-颗粒模型可以克服以连续介质力学为基础的有限元等数值方法对于模拟大变形时的局限性,可以逼真地体现爆炸载荷下裂纹的生成、扩展以及碎块的形成及飞离母体等大运动特征,且模拟结果与试验结果基本一致,该方法可用于爆炸效应数值模拟,是一种有效的手段.     

灭火救援理论和技术装备发展的需求分析

如何提高灭火救援理论和技术装备的整体水平，已成为当前公安消防部门面临的一个重要课题。对我国公安消防部队灭火救援理论和技术装备的发展进行了研究，从灭火救援实战的角度提出了当前灭火救援理论需要研究的主要课题，以及未来几年灭火救援作战和训练装备改革创新的重要需求。     

厦门金鹏花园结构设计

该工程建筑由于立面大开洞造成竖向构件转换、楼板局部不连续;上部立面收进大于25%,形成了侧向刚度突变,属超限高层建筑。本文主要介绍该工程的结构设计、计算方法、采取的构造措施。     

预应力混凝土结构中空间索线筋的预应力摩擦损失计算

在预应力工程实践中,混凝土中的预应力筋有时需布置成空间曲线索形。其预应力摩擦损失的计算应该按照空间三维曲线的曲率转角来计算。本文推导了空间索线预应力筋的摩擦损失计算公式,推荐了简化近似计算方法。通过若干实例的对比计算,表明不考虑三维效应的影响可能存在较大的误差;而推荐的简化方法则简便且精度较高。     

住宅建筑节能与可持续发展的措施研究

文章从我国目前住宅建筑的能源消耗状况、我国建筑节能设计标准的颁布与实施情况谈起,分析造成建筑节能设计标准执行不力的原因,提出为保证住宅建筑节能与可持续发展的相应措施。     

混凝-微滤组合工艺处理饮用水的中试研究

采用处理能力为300m^3／d的混凝-微滤组合工艺处理饮用水。连续监测了系统的处理效果及膜污染特性。结果表明，该系统具有良好的处理效果，出水水质满足《生活饮用水卫生标准》（GB5749-2006）的要求。系统运行期间，跨膜压差及膜比通量仅有较小程度的下降，排泥周期由24h变为48h，对膜污染和出水水质均未产生显著影响。     

Study on two operating conditions of a full-scale oxidation ditch for optimization of energy consumption and effluent quality by using CFD model

The operating condition of an oxidation ditch (OD) has significant impact on energy consumption and effluent quality of wastewater treatment plants (WWTPs). An experimentally validated numerical tool, based on computational fluid dynamics (CFD) model, was proposed to optimize the operating condition by considering two important factors: flow field and dissolved oxygen (DO) concentration profiles. The model is capable of predicting flow pattern and oxygen mass transfer characteristics in ODs equipped with surface aerators and submerged impellers. Performance demonstration and comparison of two operating conditions (existing and improved) were carried out in two full-scale Carrousel ODs at the Ping Dingshan WWTP in Henan, China. A moving wall model and a fan model were designed to simulate surface aerators and submerged impellers, respectively. Oxygen mass transfer in the ditch was predicted by using a unit analysis method. In aeration zones, the mass inlets representing the surface aerators were set as one source of DO. In the whole straight channel, the oxygen consumption was modeled by using modified BOD-DO model. The following results were obtained: (1) the CFD model characterized flow pattern and DO concentration profiles in the full-scale OD. The predicted flow field values were within 1.98 ± 4.28% difference from the actual measured values while the predicted DO concentration values were within −4.71 ± 4.15% of the measured ones, (2) a surface aerator should be relocated to around 15 m from the curve bend entrance to reduce energy loss caused by fierce collisions at the wall of the curve bend, and (3) DO concentration gradients in the OD under the improved operating condition were more favorable for occurrence of simultaneous nitrification and denitrification (SND).     

简易自动喷水灭火系统在中小型场所中的应用

通过中小型场所的火灾实体模拟试验,说明了在中小型场所中设置简易自动喷水灭火系统的可行性和重要性。     

绝缘子闪络毁伤模拟实验系统及其应用

由于绝缘子闪络毁伤与污秽闪络的机理和特性有所不同,尤其是闪络毁伤实验存在一定破坏性,因此建立专用的实验系统是相关研究的先决条件。在对高压电力系统进行分析的基础上,借鉴绝缘子人工污秽闪络实验方法,结合弹药毁伤实验的特点,研制出了能够模拟110kV电压等级的绝缘子闪络毁伤模拟实验系统。毁伤模拟实验表明,该系统性能良好,能够满足毁伤实验研究需要,为导电液溶胶电力毁伤技术的研究与开发创造了必要条件。     

Seismic response analysis of self-anchored suspension bridge with multi-tower

Seismic performance of a self-anchored suspension bridge with three-tower were investigated. A three-dimensional nonlinear finite element model of the bridge was developed using Sap2000. Nonlinear time history analysis was conducted using Fast Nonlinear Analysis Method (FNA), while beam-column effect and nonlinear behavior of bearing and damper were taken into consideration. The analyze results showed that the middle tower was more vulnerable compared with the two side towers; there existed risk of buckling of composite beam, and the most vulnerable part lied near steel-concrete composite segment. Viscous dampers were effective to reduce seismic response of towers as well as girders.