A model for automated monitoring of road construction

Monitoring and control of earthmoving operations is gaining an increasing interest. Manual monitoring and control of earthmoving operations have not yielded the expected results. Additionally, because manual monitoring is labor‐intensive, construction managers have to choose between monitoring based on rough estimates, or spending a lot of time collecting and processing data. The latter choice distracts them from many other important duties. The purpose of the present model is to automatically collect and process monitoring data providing the construction manager with real‐time control information. The model was developed for road construction. It uses GPS technology for automated data collection, logging the locations of all the earthmoving equipment while working on the project. Specially developed algorithms convert these locations to control information regarding productivity, duration (or progress) and actual consumption of materials. The model was implemented and tested for 3 weeks in a road construction project. The performance of four activities was measured by the model and compared to manual measurement of the same parameters. This comparison indicated that the model could reach a deviation of ±5%.     

整治·控制·试验：广东省村庄规划回顾与思考

村庄规划和建设是我国实现“新型城镇化”的重要任务之一。本文回顾了广东省村庄规划和建设的历程,将其大致归纳为整治型、控制型和试验型三种类型,总结了各个类型的村庄规划编制的背景、内容、经验与问题,提出村庄规划编制应着眼于全域规划、关注产业、强调实施和公众参与四个规划理念,重点在完善村庄规划的内容体系、加快制定覆盖全域的村庄用地分类标准两个方面提高村庄规划编制的技术水平。     

双弹簧支撑ETFE枕式膜结构性能研究

利用压缩弹簧代替充气形成无需充气设备的ETFE薄膜结构,采用数值分析与模型试验方法对双弹簧支撑ETFE枕式膜结构的可行性及结构性能进行研究。数值分析结果表明：膜面形状由膜面初始应力和弹簧弹力之比决定;弹簧刚度对膜面应力影响较小,增大弹簧刚度可减小膜面位移但使荷载作用下弹簧弹力的变化增大;膜面矢跨比对膜面应力影响不大,但减小矢跨比使膜面变形增大。模型试验结果表明：膜面成形可通过调整弹簧弹力完成,方法简便可靠,膜面成形精度较高;加载试验中弹簧支撑系统工作可靠,可以较好地追随并张紧膜面;支撑点处膜面应力集中不明显,试验结果与数值分析结果吻合较好。     

单向张拉膜结构气弹模型试验研究

在均匀流场中进行开敞式单向张拉膜结构气弹模型风洞试验,研究膜结构的流固耦合机理。研究表明：膜的气弹失稳主要由涡激共振引起,膜结构在风荷载作用下变形到平衡位置并围绕该平衡位置进行振动,特定风速下,流体流经平衡位置会产生旋涡。低风速下,膜以一阶模态为主振动,流场中没有任何旋涡;超过一定风速后,振动中出现了某高阶模态的响应,流场中也出现了与该阶模态主频接近的旋涡;随着风速的增大,旋涡的主频与该阶模态频率的差别越来越小进而变化到相等,后又变化到差别越来越大,导致该阶模态的共振响应越来越弱直至消失;随着风速的继续增大,旋涡的频率会与膜的其他阶模态基频接近,导致结构发生其他阶模态的涡激共振。这种涡激共振是一种周期性振荡式失稳,结构的无量纲第一临界风速约为0.84,第二临界风速约为2.27。     

刚性网格索穹顶结构的模型试验研究

通过对一直径6m的刚性网格索穹顶结构试验模型进行预应力张拉成形、竖向对称加载与非对称加载试验,研究该结构模型在静载下的力学性能。应用非线性有限元数值计算方法建立刚性网格索穹顶结构的计算模型,对结构的静力学性能进行理论计算与分析,并与试验结果进行比较。结果表明:在各加载阶段,试验模型节点竖向位移实测值与理论计算结果较接近,拉索索力实测值与计算结果吻合较好,证明模型设计和试验方法合理,理论计算方法正确。     

示踪气体法利用人体作为CO2释放源测量宿舍换气次数的方法探究

测量自然通风情况下学生宿舍的通风量对研究高校学生宿舍的室内空气品质具有重要意义。示踪气体法利用人体作为CO2释放源具有安全、方便、低成本等优点及大规模推广的可能性,但目前国内研究利用人体作为CO2释放源测量新风量的文献较少。因而,本文以高校学生宿舍单侧自然通风为研究对象,探究利用人体作为CO2释放源测量宿舍换气次数方法的可行性与可靠性。其一,验证了宿舍内CO2分布的均匀性,结果表明可仅在宿舍中心点处布置单个测点,其测试结果可代表宿舍内CO2的整体变化情况。其二,通过实验对人体CO2释放量的计算公式进行修正,得到了中国年轻女性CO2释放量的修正因子为0.75。其三,以SF6作为示踪气体进行实验对比,验证了以人体作为CO2释放源测量宿舍换气次数方法的可靠性。而后,本文分析了此方法的适用性,并指出以中国年轻女性作为CO2释放源,房间换气次数为1.5次/h时,人均最大可测房间体积约为10 m3。     

水泥土处置盐渍地基的强度试验研究

为研究水泥稳定土处置盐渍土软弱地基问题,考虑水泥掺量、含盐量和含水率三因素,进行水泥稳定土28d无侧限抗压强度试验.正交试验分析表明,水泥稳定土中含盐量的多少显著影响其无侧限抗压强度的大小;水泥掺量、含水率的改变对试件的无侧限抗压强度有一定影响,试件强度随着水泥掺量的增加而增大,随着含水率的增大而减小,其变化幅度均不明显;水泥掺量与含水率的交互作用也显著影响着水泥稳定土的无侧限抗压强度.     

不同黏结条件下SMA驱动混凝土柱轴压试验研究

对相同混凝土配合比的5组混凝土柱(1组全黏结SMA(形状记忆合金)驱动混凝土柱,1组半黏结SMA驱动混凝土柱,1组无黏结SMA驱动混凝土柱,1组全黏结SMA未驱动混凝土柱,1组素混凝土柱)进行了轴压试验研究,比较分析了5组混凝土柱的纵向应变、横向应变、极限荷载、裂现荷载等轴压性能.结果表明:SMA混凝土柱抗裂性能大小顺序为:半黏结SMA驱动混凝土柱＞全黏结SMA驱动混凝土柱＞无黏结SMA驱动混凝土柱＞全黏结SMA未驱动混凝土柱;SMA混凝土柱的极限荷载大致相等,并且都比素混凝土柱大;SMA螺旋箍筋与混凝土半黏结将有利于SMA螺旋箍筋对混凝土柱施加预应力;可利用SMA螺旋箍筋对混凝土柱施加较大的预应力,实现对混凝土柱的变形控制.     

Valuing the environment in developing countries: modelling the impact of distrust in public authorities' ability to deliver public services on the citizens' willingness to pay for improved environmental quality

In this paper, we employ the choice experiment method to estimate citizens' valuation of an intervention that proposes to improve the quality of the wastewater deposited in the Ganges River, India. We interviewed 150 randomly selected citizens of Chandernagore, along the banks of the Ganges River, to elicit their willingness to pay (WTP) for this intervention, measured in terms of higher municipality taxes. The findings reveal that almost all of the citizens value wastewater quality, though majority protested the intervention, and stated that they donot trust the authorities for effective management of funds. These protest responses were controlled for with the nested logit model. The results reveal that the citizens are willing to pay significant amounts for improved wastewater quality. Municipalities could rely to some extent on their citizens' WTP higher taxes but municipalities' performance, trustworthiness, accountability, as well as the citizens' perceptions of these, should be improved.