成束PVC电缆全尺寸火蔓延实验研究

对最常见的PVC电缆进行了全尺寸实验研究.通过测量电缆的炭化长度及电缆表面的温度研究火蔓延的情况,同时将火蔓延与火灾过程中的重要参数(如热释放速率、烟气释放速率)进行了比较,对影响电缆火蔓延的因素进行了分析.研究发现,PVC电缆的火蔓延过程可分为两类:一类可以维持火焰传播,另一类在离开点火源后火焰逐渐熄灭;影响电缆火蔓延的关键因素为电缆的排布方式,当电缆为间隔排列时,火焰可以维持传播,当电缆为紧密排列时,火焰在电缆束中段熄灭;电缆束宽度和点火源功率对电缆火蔓延的影响很小.     

PCC桩水平承载特性足尺模型试验研究

桩在水平荷载作用下的受力性状是一个复杂的桩土相互作用过程。针对双层地基中现浇混凝土大直径管桩(以下简称PCC桩)受水平荷载的问题,利用河海大学岩土所自行研制开发的大型试验模型槽进行水平承载桩静载足尺模型试验,实测得到了水平荷载下PCC桩与土共同作用时的工作性状,分析了PCC桩受水平荷载时的内力、变形、极限承载力和桩侧土压力分布等。试验结果可为今后类似土层下水平受荷PCC桩的设计与研究提供参考。     

新型装配整体式混凝土结构主次梁节点试验研究

通过4组8个混凝土结构足尺试件的单调静力加载试验,进行了新型装配整体式混凝土结构叠合主次梁节点及现浇对比节点的模型试验研究。试验表明:试件截面应变基本满足平截面假定,破坏源于节点区附近次梁的受弯破坏,叠合试件中预制部分与现浇部分之间基本未出现滑移,按规范公式计算叠合试件抗裂能力和抗弯承载力是安全的。     

Collaborative futuring with and by makers

Maker spaces and maker activities offering access to low-cost digital fabrication equipment are rapidly proliferating, evolving phenomena at the interface of lay and professional design. They also come in many varieties and change fast, presenting a difficult target for, for instance, public authorities, who would like to cater for them but operate in much slower planning cycles. As part of participatory planning of Helsinki Central Library, we experimented with a form of collaborative futuring with and by makers. By drawing elements from both lead-user workshops and participatory design, we conducted a futuring workshop, which allowed us to engage the local maker communities in identifying the issues relevant for a public maker space in 2020. It further engaged the participants in envisioning a smaller prototype maker space and invited them into realising its activities collaboratively. Our results indicate that particularly the information about future solutions was of high relevance, as was the opportunity to trial and elaborate activities on a rolling basis in the prototype space. Insights about more general trends in making were useful too, but to a lesser extent, and it is likely that these could have been gained just as easily with more traditional means for futuring.     

密集横隔板UHPC箱梁锚固区局部承压性能研究

为获得密集横隔板UHPC箱梁"隔板连通式齿块"的局部承压受力特征及承载能力,该文以某拟建UHPC箱梁桥为工程背景,通过大吨位张拉试验及非线性有限元模型对UHPC箱梁锚固区进行了受力分析,得到了以下结论:UHPC锚固区局压开裂为UHPC的拉应力控制;"隔板连通式齿块"中"局部弯曲效应"和"径向力效应"均不显著,但"锚下劈裂效应"和"隔板弯曲效应"较为明显且为导致锚固区承载失效的重要因素;背景工程中尺寸小巧的"隔板连通式齿块"张拉到4700 kN时无开裂风险,采用25根钢绞线锚固同样能满足承载能力要求,可在实际工程中广泛采纳;UHPC锚固区的拉应变值即便进入到了拉伸应变硬化阶段锚固区仍能正常使用,为建造经济化在设计中可适当利用UHPC的拉伸应变硬化特征。此外,UHPC锚固区局压承载力基于不同承载力公式所得的计算结果差距较大（最大差值达到了40.9%）,其中基于Kim公式、《活性粉末混凝土结构技术规程》以及《超高性能混凝土结构设计技术规程》（征求意见稿）中局压承载力计算公式所得结果与FEA结果较为接近。     

六维力传感器静态标定系统误差分析

介绍了六维力传感器静态标定系统的构成,分析了标定系统的误差来源,建立了综合误差模型,并针对该误差模型提出了减小误差、提高测量精度的措施。分析结果表明,该静态标定系统的MZ通道的满量程误差为2.48%,其余通道均在2%以下。加载力的方向偏差是六维力传感器标定系统误差的主要来源,标定时应该使用高精度的方向校准设备,减小力的加载误差。     

Influence of particle size on the exit effect of a full-scale rolling circulating fluidized bed

This paper investigated the influence of particle size on the exit effect of a full-scale rolling circulating fluidized bed (CFB) by using the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) method. The gas–solid two-phase flow of the full-scale rolling CFB was compared with that of a simplified rolling CFB. Thus, the exit effect of the full-scale rolling CFB was clarified. In the air phase, a peak of air axial velocity v_ya was observed when the full-scale rolling CFB reached the maximum angular displacement. The particle phase possessed back mixing and radial exchange phenomena at the top and bottom of the full-scale rolling CFB, respectively. However, those phenomena were not obvious at the top and bottom of the simplified rolling CFB. The mechanism of the above-mentioned exit effect was then clarified by analyzing the forces acting on the particles under different particle sizes. Finally, the increases in particle size lead to the intensification of the peak of v_ya, particle back mixing, and radial exchange phenomena. Therefore, the intensity of the exit effect of the gas–solid two-phase flow increased as the particle size increased_. The results suggested that the small particles had the potential to promote the purification rate of the full-scale rolling CFB on account of its small exit effect.     

深度特征融合注意力与双尺度的运动去模糊

目的 拍摄运动物体时,图像易出现运动模糊,这将影响计算机视觉任务的完成。为提升运动图像去模糊的质量,提出了基于深度特征融合注意力的双尺度去运动模糊网络。方法 首先,设计了双尺度网络,在网络结构上设计高低尺度通路,在低尺度上增加对模糊区域的注意力,在高尺度上提升网络的高频细节恢复能力,增强了模型去模糊效果。其次,设计了深度特征融合注意力模块,通过融合全尺度特征、构建通道注意力,将编码的全尺度特征与解码的同级特征进行拼接融合,进一步增强了网络的去模糊性能和细节恢复能力。最后,在双尺度的基础上,引入多尺度损失,使模型更加关注高频细节的恢复。结果 在3个数据集上,与12种去模糊方法进行了对比实验。在GoPro数据集上得到了最优结果,相比SRN （scale-recurrent network）方法,平均峰值信噪比提升了2.29 dB,能够恢复出更多的细节信息。在Kohler数据集上,得到了最高的峰值信噪比（29.91 dB）。在Lai数据集上,视觉上有最好的去模糊效果。结论 实验结果表明,本文方法可以有效去除运动模糊并恢复细节。     

直驱式风力发电系统全功率并网变流器拓扑结构研究

在主流的变速恒频风力发电机组中,由于直驱式风机具有结构简单、效率高、维护费用低、并网控制灵活以及优良的低电压穿越性能等优势,所以愈加受到关注.对比分析了目前直驱式变速恒频风力发电系统全功率并网变流器主电路拓扑结构,并得出了结论,双PWM变流器具有较广泛的应用价值.     

全面建设小康社会需要高度发达的信息化支持

党的十六大确立了全面建设小康社会的目标。如何认识和理解全面小康社会目标与信息化建设的关系，信息化建设在全面建设小康社会中的地位和作用，为实现全面小康社会，在推进信息化进程中要处理好哪些关系，应引起各通信运营企业的关注。