Performance of Pultruded Jute Fibre Reinforced Phenolic Composites as Building Materials for Door Frame

The pultruded jute/phenolic composites were aged under various humidity, hydrothermal and weathering conditions. Aging-induced effect of these conditions on the jute profiles was studied in terms of their physico-mechanical properties. It is observed that dimensional change of the profiles was only upto 4% even in an accelerated water aging condition. The effect of absorbed moisture/water on the jute profile was more pronounced in an accelerated water aging than the samples are being exposed to high humidity and alternate wetting and drying cycles. The changes in the values of internal bond strength of the profiles could be used as an indicator because of its sensitivity towards aging. Accentuation of fibres on the weathered samples along with severe resin erosion has suggested to layer the surface of the profiles with rich resin prior to use in the outdoor. The properties of jute profile door frame were satisfactory when compared with the requirements mentioned in IS: 4021–83 – Indian standard specification for timber door, window and ventilator frames. Performance of the installed door frame has shown no sign of dimensional instability in terms of warping and bulging after 3 years. It is suggested that jute door frames could be used as an alternative to the wooden door frames in buildings.     

MPA法和Pushover法在掉层框架结构中的适用性对比分析

结合已有的规则结构分析结果,设置不同的掉层跨数、掉层数量的掉层结构,以逐步增量弹塑性时程分析(IDA)结果为依据,运用多模态Pushover法(MPA)和传统的Pushover法进行对比分析。结果表明:相对于规则框架结构,除MPA外,掉层结构的掉层部分在各类侧向力分布模式相对于IDA下的层间Pushover曲线有较大差异。SRSS分布下在掉一、二层位置,过高估计结构的响应。上接地层以上部位各侧向力下的层间Pushover曲线较IDA曲线误差较小。掉层的楼层的层剪力在上接地位置存在明显的突变。掉层跨数的改变对上部楼层弹塑性分析结果影响较小,但跨数的改变会改变同等烈度下结构的层间Pushover曲线和内力响应。与此同时,掉层跨数的增加会减轻"剪力突变"现象。伴随着掉层层数的增加,掉层部分均匀分布和倒三角分布与IDA下层间推覆曲线的差异会扩大。总之,相对于传统Pushover分析,MPA分析的结果更接近于相对准确值,需要进一步研究以提高精度。     

强膨胀软岩巷道锚网喷架联合支护技术研究

强膨胀软岩巷道的支护问题是西部地区矿井建设中普遍遇到的难题。为解决强膨胀软岩遇水泥化、崩解等给巷道掘进、支护等工程带来的困难,以强膨胀软岩巷道支护工程为研究对象,通过理论分析和现场调研,研究强膨胀软岩巷道变形机理;利用有限元分析软件MIDAS/GTS建立强膨胀软岩巷道数值仿真模型,分析了锚网喷架联合支护时巷道塑性区范围、表面位移和钢支架的受力特征。进行现场测试,获得了巷道围岩变形和锚杆受力变化规律。结果表明,采用钢支架与锚网喷构成联合支护体系可有效提高支护结构整体刚度,提升围岩的自稳能力和自承能力。     

基于方位轴旋转的平台惯导系统对准策略研究

目的解决平台惯导静基座自对准精度受到平台转位、锁定及惯性仪表误差影响的问题。方法提出一种绕方位轴变速旋转的平台惯导连续自对准方法。该方法基于平台按照方位陀螺力矩指令绕方位轴变速旋转,采集水平陀螺的力矩电流输出信息估计平台失准角及仪器误差系数。通过输出灵敏度理论对系统的可观测度进行分析后,采用建立虚拟平台系的参数估计方案使得方位失准角估计精度得到提高。结果当测量噪声为0.01(°)/h(1σ),方位失准角对准精度在10″以内,对准过程可以在10 min内完成。结论该方案及算法使惯导平台静基座自对准精度得到显著提高。     

Socio-environmental conflict in the construction of a power plant in Spain's Basque Country: strategies,expertise and certifications

Social and anthropological studies show a growing number of conflicts surrounding energy projects, as governments and companies insist on their implementation despite the concerns of local actors about their perceived socio-environmental risks. In this context, the purpose of this paper is to analyse the politicisation of expertise and certifications in a conflict over the construction of a combined cycle power plant by linking strategic assumptions from two particular sociological approaches. The first approach is based on the study of frame alignment in social movement organisations and the second on the translating interests in actor–network theory. These linked premises are examined in the conflict arising from the construction of a combined cycle natural gas plant in Boroa, in the Basque Country of Spain. This case study brings to light interesting findings on the strategies of the different agencies, certifications, politicisation of expertise and the increasing hostility in local conflicts.     

汶川地震典型教学楼附加BRB支撑防倒塌加固效果分析

以汶川地震震中附近的一栋典型RC框架结构为背景,采用BRB支撑加固来增强其抗震能力,并采用基于动力增量分析(IDA)的地震倒塌易损性分析方法,对加固后的抗倒塌能力及其影响参数进行了分析。结果显示,以结构抗倒塌能力为目标,BRB支撑方案的加固效果要好于普通支撑加固方案,相同参数情况下,A形支撑布置方案的加固效果好于X形支撑布置方案。     

Public receptiveness to policies promoting plant-based diets: framing effects and social psychological and structural influences

Governmental and non-governmental organizations, social movements, and academics have called for reductions in meat consumption due to the environmental, animal welfare, and public health consequences of industrial animal agribusiness. An impactful move toward plant-based diets would require changes in public policy. First, we assess if there are different social and structural factors that influence support for policies that promote plant-based diets. We look at four categories of policies (action frames) that will likely reduce meat consumption: environmental, animal welfare, public health, and direct meat reduction. Second, we use a manipulation rhetorical frame to see if support can be altered by providing individuals with information about meat reduction, framing the issue in terms of environmental protection, animal welfare, or public health. Different social and structural factors predict support for different policy groupings, meaning that it matters how policies are enclosed in action frames. However, providing information to individuals about a particular impact (rhetorical frame) has limited influence on policy support.     

基于虚拟仿真的过山车轮架疲劳寿命分析

针对过山车轮架结构疲劳问题的特点和传统疲劳分析方法的不足,研究了基于虚拟仿真的结构疲劳寿命分析方法;采用多种虚拟仿真手段,对过山车进行了多体动力学分析,对轮架结构进行了有限元分析及动态响应分析,对比了多轴疲劳理论的各种损伤模型的特点和适用范围,分别依据最大剪应变准则和Brown-Miller组合应变准则对轮架结构进行了寿命分析,给出了疲劳寿命,并找出了轮架结构的薄弱部位。基于虚拟仿真的过山车轮架疲劳寿命分析方法,为过山车的设计制造、日常维护、安全监察提供了科学依据,同时为结构的多轴疲劳分析提供了新思路。     

基于成本-效益准则的高层RC框架结构优化设计(Ⅰ)——方法

成本-效益准则是基于性能的抗震设计的重要原则,该准则在设计中除了考虑技术要素外,还考虑经济、社会等诸多因素,它所追求的设计目标为结构在其寿命周期内的总造价最小.因此,结构全寿命造价评估是基于性能的抗震设计的基本问题.在已有全寿命造价优化模型的基础上,提出了三目标函数全寿命造价优化模型.与已有的全寿命造价模型相比,该模型除考虑结构初始造价、损失期望外,还考虑了反映结构设计与施工复杂性的构件截面类型数量;另外,还将结构在其运行期间的检查、维护费用及由于优化导致建筑使用面积变化所引起的租金收益影响也列入到结构全寿命造价中.最后,基于所提出的优化模型,给出了以多目标遗传算法为搜索引擎、运用MATLAB语言开发的高层RC框架结构基于成本-效益准则的自动优化程序流程图.     

我国环境保护政策框架体系改革的几点思考

针对当前越来越热的“环保改革”话题，从现实和发展两个方面详细阐述了环保改革的必要性和目标，指出了改革中的重点和难点问题，强调必须建立新的管理体制和政策框架，在此基础上提出了推进和完善排污权交易试点的对策建议。