Premixed hydrogen-air flame front dynamics in channels with central and peripheral ignition

Experimental and analytical study of burning hydrogen-air mixtures with 12, 13, and 15 vol% hydrogen concentrations in channels with central and peripheral ignition was performed. Flame propagation speeds were determined by shadow and infrared high-speed imaging in the transverse and longitudinal directions, respectively. It was found that the increase in the flame front speed during the peripheral ignition reaches up to 1.7 times compared to the central ignition depending on mixture content. The pressure growth rate was examined in a closed channel. It was estimated that the time to reach a maximum pressure is 1.1 times less in the case or peripheral ignition than the central one. An analytical model was formed to describe the dynamics of the flame front in both cases. The model of a “reversed finger-flame” generated by a peripheral ignition was presented. The obtained results could be used in designing hydrogen-fueled combustible engines with the reduced knock-effect.     

Energy and environmental comparison of three variants of a family house during its whole life span

The aim of this study is to analyse and compare three variants of a family house in order to evaluate the total environmental impacts produced during the whole building life cycle. The first variant corresponds to the standard in force in Switzerland, the second alternative to the requirements of a quality control label for houses with low energy consumption and the third case is a very low energy consumption building. The three variants have the same architectural aspect but different insulation thicknesses and types, different energy production systems and the use of different renewable energies. The calculation of the environmental impacts is carried out by means of a life cycle analysis, which includes not only the impact related to the energy consumption during the occupancy stage, but also the materials manufacture, transport, replacement and elimination at the end of the building lifetime. The results are expressed with the Swiss and the UCTE (Union for the Co-ordination of Transmission of Electricity) electricity mix to analyse how they influence the building impact.     

Parental background and housing outcomes in young adulthood

Abstract

Scholars and policy-makers are concerned that young adults’ housing opportunities are becoming more dependent on their family background. This could hinder social mobility and exacerbate inequality. Using data from three cohorts of young people drawn from the Office for National Statistics Longitudinal Study of England and Wales, this study examines how parental attributes in childhood are linked to young adults’ housing outcomes two decades later. The results show that young adults’ housing outcomes have changed considerably over time and are persistently stratified by parental class and tenure in ways that vary by gender. Housing outcomes have become somewhat more polarised by parental tenure over time as the children of renters became relatively less likely to enter homeownership and more likely to rent privately. This suggests that renters became an increasingly ‘marginalised minority’ in the late twentieth century, with consequences for their children’s housing careers and future social inequality.     

圩-垛田景观格局下的“水-田-村”布局模式

江苏省兴化地区位于里下河平原腹部的低洼地带,为万水交汇之地,其极具浓郁地域色彩的圩–垛田景观近年来受到众多学者的广泛关注。在区域尺度下,从水文环境变迁和人居环境建设两方面,归纳兴化地区圩–垛田景观发展的演变动力;在市域尺度下,分析兴化地区水利系统、农业开垦及聚落布局的地带特征。从形态学角度,研究兴化地区由东至西,自然地势不断降低、水网逐渐稠密、土地肌理愈发破碎,农田形态发育与聚落形态发展之间的内在关系,以及圩–垛田景观格局下,兴化地区独有的“水–田–村”布局模式。圩–垛田景观的形成是千百年来水与土地不断分解与整合后的结果,圩–垛田景观格局的发展和演变展示了兴化地区传统人居环境营建与自然系统之间相互选择、相互适应的过程,显示了劳动人民治水、农耕和营居的古老智慧。     

内外业一体化地名地址普查及信息系统建设

基于提高地名地址普查效率和快速搭建地名地址普查及系统的目的,采用了室内室外一体化地名地址普查手段和应用"天地图"地理信息平台的方法,结合了地名地址普查的实际生产过程经验,得出了充分利用已有的地理信息资源、先进的测量设备、成熟的共享信息平台,能够提高地理信息相关行业获取行业专题数据的效率以及实现信息系统快速建设。     

Revit族在砌体排布施工中的应用探索

Revit族的本质特性是"参数化"。在Revit的项目中,族实例的堆砌形成了不同规模、风格各异的建筑形态。为了控制和区分族实例,Revit通过族类型属性和族图元属性中的参数来对图元进行管理。但是这些族是智能化的模型,需要专业人员基于Revit的插件和工具进行参数化的设计。依托窗族创建砌体的族类型并紧密联系砌体施工,提出精确、绿色的砌体排布方法。研究结果表明:基于已有的Revit族创建能满足实际工程要求的族类型并付诸实践是实施精益施工、促进BIM应用全面发展的新方法。     

深埋复杂不规则孤岛工作面冲击矿压机制研究

为研究大埋深下不规则孤岛工作面开采对冲击矿压的影响,基于覆岩空间结构理论,分析了某矿3112孤岛工作面覆岩结构及其大尺度破断运动对工作面煤岩体的影响,并根据掘进期间微震监测对孤岛面的回采进行冲击危险的动态评价。通过理论分析与数值模拟,从煤岩体静载应力和动态破坏2方面分析孤岛煤柱诱冲机制。基于能量守恒定律,研究了主关键层破断瞬间覆岩稳定性和能量释放、转化过程,主关键层的破断运动对工作面矿压显现影响剧烈。数值计算分析了不同开采尺度对孤岛面冲击的影响,随着开采尺度的增大,煤体的静载应力峰值逐渐升高并接近临界应力,冲击危险程度升高。最后基于动静载组合诱发孤岛煤柱冲击机制,探讨了孤岛面冲击矿压防治措施。现场实践表明,钻孔卸压和顶板预裂爆破有效地控制了高能量震动事件的产生。     

5083 H321铝合金板材制备组织性能研究

基于“1+4”热连轧生产线、2800mm冷轧生产线,采用不同工艺线路制备了5083 H321铝合金板材,研究了不同制备工艺对板材组织性能的影响。结果表明,不同工艺路线成品板材力学性能、耐腐蚀性能及微观组织均存在明显差异。采用“1+4”热连轧生产线短流程工艺制备的5083 H321铝合金板材性能:抗拉强度358MPa、屈服强度257MPa、延伸率17%、剥落腐蚀等级PA、晶间质量损失3.22mg/cm2。     

我国资源型城市“高碳锁定”的内在机制及解锁路径——以安徽省淮北市为例

从“高碳锁定”效应在资源型城市中的表现及其影响切入,以安徽省淮北市为例,从技术层面、产业层面、制度层面及其综合层面分析我国资源型城市“高碳锁定”的内在机制,进而结合淮北实际,探讨了资源型城市“高碳锁定”的解锁路径与策略.