高强钢筋高强混凝土双连梁剪力墙抗震性能试验研究

高强钢筋、高强混凝土剪力墙结构中使用双连梁可以有效改善结构受力性能,解决设计中经常遇到的诸如连梁超筋、截面受剪承载力不足等问题。基于此,设计并制作了2个3层1/4缩尺的高强钢筋高强混凝土双肢剪力墙试件,其中一个试件的连梁采用单连梁形式,另一个试件的连梁采用双连梁形式。在相同的试验条件下,对比研究二者在低周反复荷载作用下的承载力、滞回特性、延性、耗能能力,分析双连梁结构形式在高强钢筋高强混凝土双肢剪力墙中的性能及作用。试验结果表明：具有相同配筋率的分缝双连梁双肢剪力墙结构与小跨高比单连梁双肢剪力墙结构相比,承载力降低了20%～30%,延性增加了约30%,耗能能力增加了约20%,在弹性阶段刚度降低约30%。从最终的破坏形态来看,单连梁剪力墙试件连梁出现了明显的剪切斜裂缝,箍筋全部屈服,最终发生剪切破坏;双连梁剪力墙试件只在连梁端部出现了弯曲裂缝未出现斜裂缝,箍筋自始至终未屈服,最终发生弯曲破坏。双连梁剪力墙结构能有效降低连梁内力,提高其延性。     

基于CSD/CFD舵面气动力流固耦合仿真分析

空空导弹空气舵面与气动力存在流固耦合作用。采用ANSYS Workbench 14.5对空气舵面与气动力进行了流固耦合仿真分析,研究了攻角和马赫数对舵面振动位移的影响。研究表明,舵面振动位移频率受攻角和马赫数的影响较小,舵面振动位移幅值随攻角和马赫数的增大而增大,并呈非线性关系。低马赫数范围内,飞行速度的变化对舵面振动位移的影响更为明显。攻角为30°,马赫数为3时,舵面振动位移曲线更趋向于等幅振动,舵面趋向于颤振临界状态。     

纸质地图的作用及对策研究

纸质地图作为人们出行的助手,受到电子地图越来越多的冲击,有人质疑纸质地图即将被电子地图所取代。本文结合纸质地图和电子地图的优劣对比,阐述了纸质地图在现代社会生活中应该发挥的作用,强调了其在辅助出行、普及地理知识、军事价值、专题图应用和文史价值方面的意义。同时结合工作实践重点介绍了纸质地图面临冲击所采取的应对措施。     

重质碳酸钙对丙烯酸酯乳液改性乳化沥青防水涂料性能的影响

研究探讨了重质碳酸钙的掺入对丙烯酸酯乳液改性乳化沥青防水涂料性能的影响。结果表明,当重质碳酸钙的含量不超过临界填料体积浓度(CPVC)时,涂料的拉伸强度、断裂伸长率、黏度及施工应用性能均明显增加,但低温性能受其影响较小;当重质碳酸钙的含量超过CPVC时,涂料的拉伸强度与断裂伸长率骤降,黏度剧增,低温柔性也会出现较大幅度的衰减。     

Erratum to: Experimental research on overlying strata movement and fracture evolution in pillarless stress-relief mining

International Journal of Coal Science & Technology -     

Fast accessing Web3D contents using lightweight progressive meshes

Accessing Web3D contents is relatively slow through Internet under limited bandwidth. Preprocessing of 3D models can certainly alleviate the problem, such as 3D compression and progressive meshes (PM). But none of them considers the similarity between components of a 3D model, so that we could take advantage of this to further improve the efficiency. This paper proposes a similarity‐aware data reduction method together with PM, called lightweight progressive meshes (LPM). LPM aims to excavate similar components in a 3D model, generates PM representation of each component left after removing redundant components, and organizes all the processed data using a structure called lightweight scene graph. The proposed LPM possesses four significant advantages. First, it can minimize the file size of 3D model dramatically without almost any precision loss. Because of this, minimal data is delivered. Second, PM enables the delivery to be progressive, so called streaming. Third, when rendering at client side, due to lightweight scene graph, decompression is not necessary and instanced rendering is fully exerted. Fourth, it is extremely efficient and effective under very limited bandwidth, especially when delivering large 3D scenes. Performance on real data justifies the effectiveness of our LPM, which improves the state‐of‐the‐art in accessing Web3D contents. Copyright © 2015 John Wiley & Sons, Ltd.     

基于重力矢量测量的惯性平台摇摆动态精度测试方法研究

为了准确高效地评估高精度惯性平台的摇摆动态精度,提出了一种基于重力矢量测量的惯性平台摇摆动态精度测试方法。惯性平台台体在摇摆过程中稳定在惯性空间,通过安装在平台台体上的3个正交方向的石英加速度计测量重力矢量,重力矢量在台体上的投影角直接反映平台台体的姿态变化,根据测量方法误差及石英加速度计输出特性进行姿态解算,并通过计算惯性平台动静漂移率之差得到惯性平台的摇摆动态精度。惯性平台的摇摆试验结果表明,基于重力矢量测量的惯性平台摇摆动态精度测试方法稳定性好、可信度高,并在误差控制方面明显优于传统的摇摆测试方法。     

Preparation of borate–modified expandable graphite and its flame retardancy on acrylonitrile‐butadiene‐styrene resin

A borate‐modified expandable graphite (written as MEG) was prepared through one step intercalating reaction of natural graphite, using KMnO₄ as oxidant, H₂SO₄ and sodium tetraborate as intercalator and assistant intercalator, respectively. The dilatability, structure, element contents, thermal stability, and flame retardancy on acrylonitrile‐butadiene‐styrene (ABS) were investigated. Compared with the normal expandable graphite (written as EG, which was prepared with only H₂SO₄ as intercalator), the results show that MEG exhibits higher expandable property, thermal stability and flame retardancy on ABS. The EDS, FT‐IR, and XRD results reveal that borate has been inserted into graphite layers. With the addition of MEG or EG at a 30 wt%, LOI of 70ABS/30MEG composite improved to 27.9%, 2.2% higher than that of 70ABS/30EG. Moreover, the synergistic effect between MEG and traditional intumescent flame retardant (IFR, consists of ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL) with a mass ratio of 7.5:4.5:3.0) improves the LOI of 70ABS/15MEG/15IFR composite to 32.6%, and the UL‐94 level reaches V‐0. This synergistic efficiency is attributed to the formation of continuous and compact residual char. Addition of MEG together with IFR changes the ABS pyrolysis behavior, and there is not only physical synergy, but also chemical reaction. POLYM. COMPOS., 37:2673–2683, 2016. © 2015 Society of Plastics Engineers