Effects of upholstery materials on the burning behavior of real‐scale residential upholstered furniture mock‐ups

Fire spread and growth on real‐scale four cushion mock‐ups of residential upholstered furniture (RUF) were investigated with the goal of identifying whether changes in five classes of materials (barrier, flexible polyurethane foam, polyester fiber wrap, upholstery fabric, and sewing thread), referred to as factors, resulted in statistically significant changes in burning behavior. A fractional factorial experimental design plus practical considerations yielded a test matrix with 20 material combinations. Experiments were repeated a minimum of two times. Measurements included fire spread rates derived from video recordings and heat release rates (HRRs). A total of 13 experimental parameters (3 based on the videos and 10 on the HRR results), referred to as responses, characterized the measurements. Statistical analyses based on Main Effects Plots (main effects) and Block Plots (main effects and factor interactions) were used. The results showed that three of the factors resulted in statistically significant effects on varying numbers of the 13 responses. The Barrier and Fabric factors had the strongest main effects with roughly comparable magnitudes. Foam was statistically significant for fewer of the responses and its overall strength was weaker than for Barrier and Fabric. No statistically significant main effects were identified for Wrap or Thread. Multiple two‐term interactions between factors were identified as being statistically significant. The Barrier*Fabric interaction resulted in the highest number of and strongest statistically significant effects. The existence of two‐term interactions means that it will be necessary to consider their effects in approaches designed to predict the burning behavior of RUF.     

基于CAD的矿图参数识别分析

提出了基于CAD环境下的矿图标准化处理规则,给出了采区、断层等图形元素的获取方法,为矿井图形信息管理提供了有效途径。     

A new direct version of the Cook-Mayne method for wind pressure probabilities in temperate storms

The original Cook-Mayne (CM) method for obtaining a wind pressure or load of a prescribed probability is reviewed. A new direct calculation method is introduced. This does not require either Monte Carlo simulations or the assumption that extreme pressures conform to the ultimate Fisher-Tippett Type I asymptote. The required value is calculated directly with no intermediate stages. The new method still relies on the original assumptions that both the pressure coefficient and the wind dynamic head have extremes which conform to the ultimate FT1 asymptote.Violation of these two assumptions is studied in some cases where calculations based on these assumptions are compared with exact results. The direct CM method is found to retain accuracy in spite of departures from the assumptions and therefore can provide a robust design tool.     

浅谈住宅小区地下车库建设的利弊

我国以密集型多层或高层为主的住宅小区,随着私家车的日益增多,解决问题的办法大多是建地下车库。随之而来的问题是地下可能被“掏空”,而且地下建筑造价高、技术难度大,只为多建有限面积的地下空间,付出的代价可谓太多,地下工程的不可逆性又会给将来改造和土地再次利用带来困难。其他的选择是建机械式立体车库,政府主管部门制定相关政策限制小区内车位数量,鼓励兴建公共停车场,发展公共交通,更符合“以人为本”的指导思想。     

关于控制性详细规划整合的思考

以重庆市江北区中心地块控制性详细规划整合为例,提出控制性详细规划整合问题出现的诱因,控制性详细规划整合的基础、依据,并总结出控制性详细规划整合工作的研究重点,说明控制性详细规划整合在城市建设中起到的作用。     

当代大学校园建筑容量的合理调控

针对生师比逐年提高和教工住宅社会化转变等现实状况,将教工住宅用地从校园建设总用地中扣除,重新计算和分析了校园建筑容积率,建设性地提出在大学校园建设中应适当提高校园建筑的容积率,并以0.55作为定额上限的参考值。     

浅析居住区绿色空间的规划设计

对居住区绿化的产生和发展进行了分析，从生态设计和景观设计两方面对居住区绿化的规划设计进行了论述，以探寻我国居住区绿色空间规划建设中的方法和对策。     

基于频率扫描的双馈风电机组次同步控制相互作用分析

双馈风电机组中存在较多与次同步振荡频率范围耦合的控制环路,容易引发控制环路与线路串联电容补偿之间的次同步控制相互作用(SSCI)。其中双馈风电机组转子侧内环比例参数对SSCI影响显著,但由于其稳定阈值较小,在抑制SSCI时的可调范围有限,因此有必要探寻控制环路中的其他参数对SSCI的影响。在建立完善的含双馈风电机组控制环路的并网系统阻抗模型的基础上,通过波特图与灵敏度分析详细对比控制参数对系统阻抗的影响大小,采用频率扫描法揭示了控制参数对系统阻抗的影响机理。结果表明:转子侧内环积分参数直接影响系统的谐振频率与线路的临界串联电容补偿度大小,积分参数的减小能够增加比例参数的可调范围,从而有利于降低并网系统发生SSCI的风险。     

关于路边停车规划的几个问题

首先探讨了路边停车地位与作用 ,认为 :路边停车是停车系统中不可或缺的一部分 ,但只能作为路外停车的补充和配合 ,要依据不同的城市、区位特征来确定路边停车的地位与作用。接着分析了制约路边停车的道路条件、交通条件、路外停车设施、交通管理水平等制约因素。最后从系统性、协调性、动态性、可操作性 4个方面阐述路边停车规划应遵循的原则     

厚截面碳纤维复合材料远表面微缺陷超声检测

为了识别厚截面碳纤维复合材料(CFRP)远表面的微缺陷,使用递归分析方法对超声检测信号进行分析。首先在厚截面CFRP材料上打孔以模拟微缺陷,采用水浸超声脉冲反射法对不同大小的模拟缺陷进行检测。然后选取缺陷位置附近信号段,确定嵌入维数m、延迟时间τ、阈值ε等参数,对各信号段进行递归分析,得到递归图及递归定量分析结果。比较无缺陷信号和有缺陷信号的递归图,从宏观上定性确定微缺陷对超声信号的影响;比较无缺陷信号和有缺陷信号的递归定量分析结果,根据每个递归定量参数的物理意义,对缺陷产生的影响作出合理的解释。最后,使用不同中心频率探头进行实验,确定合适的探头参数。分析结果表明,使用7.5MHz高分辨率超声探头时检测效果最好;当嵌入维数为7、延迟时间为2、阈值为2时,递归图中出现异常白色区域、递归点增多且对角线结构变长,同时所选取的递归定量参数随缺陷增大而上升,表明厚截面CFRP远表面超声信号可能存在混沌结构,而微缺陷的存在会改变原有信号结构。所研究内容为实际微缺陷的定量识别及分类打下基础。