Experimentelle und numerische Untersuchungen von Brandszenarien vor Fassaden unter Berücksichtigung verschiedener Abstände

Experimental and numerical investigations of fire scenarios in front of façades considering various distances Constructional boundary conditions, e. g. walls or façades, close to ignition sources affect the fire formation and the plume. It is already known, that boundaries (e. g. walls) constrain the entrainment of air and oxygen into the plume and the combustion of gas or flammable products is completed at larger heights. How far the location of the fire sources, the building geometry and the heat release rate affect the characteristics of a flame is investigated at the Institut für Baustoffe, Massivbau und Brandschutz (iBMB) of TU Braunschweig in line with a series of experiments with a square gas burner. For the implementation of the fire tests the test rig in Braunschweig is provided with extensive measurement techniques to determine heat flux, wall‐bounded temperatures, temperatures for plume measurements and upward velocity. In this paper the data of the fire tests are discussed and compared with the results of a CFD‐Model and selected empirical calculation approaches.     

Gradientenbetontechnologie

The technology of graded concrete – From the development of concrete mixtures and the conceptual design to the automatized manufacturing In accordance with the principle form follows force, the DFG Priority Programme (SPP) 1542 – Leicht Bauen mit Beton – focuses on energy efficient building elements which are designed specifically for desired operational demands. This concept is a specific adaption of the component's inner structure and works in parallel to the optimization of its outer shape which is often limited due to the outer geometry of slabs, walls and supporting pillars. The technology of graded concrete provides an innovative possibility to adapt the inner structure of a concrete component in order to meet defined static and structural‐physical requirements. The challenging demands imposed by the technology of graded concrete require a holistic approach including the development of the concrete mixtures, the design of the building components and finally the automatized manufacturing. In collaboration between the departments ILEK, IWB and ISYS of the University of Stuttgart a complete process chain for the manufacturing of functionally graded concrete components was realized. This approach for concrete results in fully recyclable building elements with significant savings in mass and energy.     

Seismic response of self‐centering precast concrete frames with hysteretic dampers

With the rapid development of cities and the invasion of major natural disasters such as earthquakes, the resilience city as a new design concept has been paid more and more attention. As an important branch of self‐centering seismic resisting system, self‐centering concrete frame system has been studied by many scholars. These studies prove that self‐centering concrete frame structure has excellent self‐centering ability but poor energy dissipation capacity. Adhering to the working principle of self‐centering structure and considering the development concepts of building industrialization and modularization, this paper proposed a kind of self‐centering precast concrete frame with hysteretic damper (SCPCHD). In order to verify its energy dissipation capacity and seismic performance, elaborate finite element models were established and elastoplastic dynamic time history analyses were carried out. The results showed that the SCPCHD frame has a similar interstory displacement response to the reinforced concrete (RC) frame and the energy dissipation performance of its joint is obviously superior to the RC frame under rare earthquake because the SCPCHD frame has low damage characteristics and excellent damping device. In summary, this paper proves the feasibility and superiority of the SCPCHD frame, providing reliable support for further research.     

快干羟基丙烯酸酯乳液的合成及性能研究

采用核壳乳液聚合方法制备了羟值为1.5%的低羟丙烯酸酯乳液。研究了聚合物理论Tg、壳中羟基质量分数、核聚合物Hansch参数对双组分漆膜干燥速度的影响。结果表明:漆膜干燥速度随理论Tg、壳中羟基质量分数及核聚合物Hansch参数的增加而加快,当Tg为50℃、壳中羟基质量分数为1.1%、核聚合物Hansch参数为3.43时,漆膜于25℃、60%相对湿度下的实干时间可缩短至95 min,在大巴、工程机械涂装等需要快干的领域具备潜在应用价值。     

PS模板法制备铜纳米颗粒

采用双槽电化学腐蚀法制备多孔硅(porous silicon, PS), 对其进行超声后处理.以PS为模板采用一步浸渍沉积法制备大小均匀、形状规则的铜纳米颗粒, 并研究沉积时间对纳米颗粒形状、尺寸的影响.结果表明:PS超声后处理并未造成其物理和化学结构的破坏, 大量的硅氢键(SiH_x)和蜂窝状多孔结构(直径150 nm左右)分别为纳米铜的形成和生长提供了还原剂和场所;沉积时间对铜纳米颗粒形貌具有重要影响, 当沉积时间为40s时得到形状和尺寸较为均匀的铜纳米颗粒.     

高纯度纳米硅粉的制备及其在水中的分散工艺研究

采用直流电弧等离子体蒸发法制备高纯度纳米级硅粉, 利用X射线衍射、X射线荧光分析、氮氧分析仪、透射电子显微镜和相应的选区电子衍射等测试手段对样品物理化学性质进行表征。采用紫外分光光度计法研究超声时间和不同的分散剂及其加入量对纳米硅粉在水介质中分散效果的影响。结果表明:制备出近球形、立方晶型结构的纳米硅粉, 粒径分布窄, 其纯度达到99.93% (质量比)。随着超声时间和分散剂浓度的增加, 分散效果呈现先增大后趋向平稳的趋势, 十六烷基三甲基溴化铵 (CTAB) 对纳米硅粉在水介质中的分散效果最好。纳米硅粉在水介质中较好的分散工艺为:在pH=6、超声功率为560 W的情况下, CTAB加入量为4%, 超声时间为80 min。分散后的硅粉比未分散的硅粉首次放电比容量提升14.93%, 达到了2640 m Ah/g, 首次库伦效率达到34.92%。     

Design of JPEMFC Fabricated with Porous Silicon

A novel material porous silicon is used as diffusion layer in pPEMFC (micro proton eXchange membrane fuel cells) for its loose and porous structure and compatibility with IC process. Study of the formation of porous silicon and metal sputter deposition on the porous silicon is performed. A fabrication process of pPEMFC based on the technology of MEMS and film deposition is presented.     

新式顺序触发开关电路

介绍了一种利用双向可控硅构成的顺序开关电路,并分析了工作原理.试验表明,此电路具有结构简单,布线方便等特点,宜于实际应用.