Sustainable mobility transitions and the challenge of countervailing trends: the case of personal aeromobility

Research on sustainable mobility transitions has focused on battery-electric vehicles, urban ‘smart’ cars, fuel-cell powered transport modes and power-assisted bicycles. While these studies have usefully exposed some of the dynamics governing sociotechnical change, developments outside the purview of sustainability have been largely ignored. A critical area of neglect concerns the growing popularity of personal aeromobility. Passenger dissatisfaction with commercial airlines, public concerns about terrorism, increasing affluence and creative marketing have expanded interest in private aviation. In parts of the USA, customised air travel is becoming a straightforward and affordable transport alternative. This article describes the mounting popularity of four segments of this trend: business/personal airplane acquisition, fractional aircraft ownership, flight-time cards and air taxis. It also highlights the role that the federal government is currently playing to overcome the technological obstacles to more pervasive personal aeromobility. A concluding section considers the ramifications of these activities on contemporary efforts to foster sustainable mobility and to conceptualise viable transition pathways.     

Developing new urban public transport systems: An irrational decision-making process

The decision-making process for planning new urban public transport systems in the UK is examined by studying 11 new and planned systems. The objectives of building the systems relate to transport and development issues. A number of key factors are taken into account during the decision-making process: forecast demand, image, deregulation of buses, technological innovation, private sector involvement and the funding mechanism. The requirement for proven technology and the forecast demand for the systems reduces the choice to one of light rail or bus. The effects of bus deregulation, funding and image, essentially reduce that choice to light rail or nothing. Cost should be kept low, which suggests a bus based system, but current legislation favours more expensive light rail systems. The conclusion is that although transport planners make rational decisions within the current political framework, the framework, and therefore some of the decisions, are not rational.     

利用可编程逻辑控制器实现交通信号灯的控制

文章主要是采用西门子公司的可编程逻辑控制器PLC-200来实现交通信号灯的控制。     

铁路车站站内计轴轨道电路抗干扰方案的探讨

铁路车站站内计轴轨道电路由工务施工造成干扰是普遍存在的问题.通过对铁路车站站内计轴轨道电路几种抗干扰方案的研讨,阐述了各方案的特点,比较得出最优方案,即利用计轴点相邻轨道区段的状态和时间双重条件,对计轴轨道区段内“±1轴”进行冗余设计,以提高站内计轴设备的抗干扰能力,使设备的安全性得到保证.     

加筋聚苯乙烯轻质膨胀土室内试验研究

为了研究加筋聚苯乙烯轻质膨胀土的膨胀与强度特性,将聚苯乙烯颗粒与膨胀土混合,聚丙烯纤维作为加筋材料,开展了包括密度、无荷膨胀率、膨胀力以及饱和快剪等室内试验。结果表明,聚苯乙烯颗粒和聚丙烯纤维的掺入可有效抑制膨胀土的膨胀特性,表现为无荷膨胀率与膨胀力的显著减小;聚苯乙烯颗粒主要起到体积置换作用,土样密度以及膨胀力随聚苯乙烯颗粒掺量增加线性减小;随着聚苯乙烯颗粒的增加,混合土内摩擦角持续增大,黏聚力先增加后降低;随着纤维掺量的增加,混合土的黏聚力得到有效增长。因此,加筋聚苯乙烯轻质土在改良膨胀土方面具有良好的应用价值。     

空心楼盖施工技术与应用的探索

本文以某框架结构的项目工程为例,探讨采用GBF高强轻质薄壁管现浇空心楼盖的施工工艺技术。以供与大家交流学习。     

互联网金融是否放松了文化创意企业融资约束？

剖析互联网金融对文化创意企业融资约束的影响,可以为互联网金融对经济增长的促进作用提供微观证据。在分析文化创意企业融资约束的形成机制及互联网金融发展对其影响机制的基础上,以欧拉方程投资模型和修正的托宾Q模型为基础,利用2009—2014年沪深上市的153家文化创意上市公司的非平衡面板数据,考察其融资约束状况,并检验互联网金融发展对其融资约束的缓解作用。研究结果表明,中国文化创意上市公司存在较为严重的融资约束问题;互联网金融发展能降低文化创意企业投资对现金流的敏感度,即可缓解其融资约束;在不同的企业所有权以及资产轻重程度的情况下,互联网金融发展的上述效应有不同的表现。     

8 mm脉冲磁控管测云雷达测速多普勒化

8 mm磁控管发射样本中频信号的起始相位随机分布,脉间频率抖动范围为±2 MHz ,脉内频率变化为500 kHz。为了克服这些问题,提出了一种适合于国内第一套毫米波 脉冲 磁控管测云雷达的测速多普勒化算法,幅度信息从回波数字下变频经低通滤波器后直接提取 , 相位信息由零中频回波IQ信号与发射样本IQ信号进行复卷积提取,并算法仿真结果表明多 普 勒频率误差不超过4 Hz。基于FPGA技术实现了测速多普勒化算法,利用高速缓存的设计 思想 实现了复卷器的优化,利用CORDIC算法实现了幅度与相位的高精度提取,并完成了算法在实 际 雷达系统中的测试,雷达的脉冲重复频率为1 000 Hz,多普勒频率在-496～500 H z范围内,雷 达终端显示的速度值与理论值一致;回波信号幅度值为-76～6 dBm,得到的速度值 与理论值 一致。经过该算法处理的地物杂波回波的多普勒速度在零值附近分布,云体目标的回波速度 图清晰可见。该算法已经成功应用于8 mm脉冲磁控管测云雷达系统。     

思想道德修养与法律基础课教学改革研究

思想道德修养与法律基础课程要更新教育思想,转变教育观念;关注学生需要,确立适合基础课特点的教学目标、任务和内容;坚持是非判断与价值判断的有机统一;改革教学方法,发挥学生的主体作用。只有这样切实加以改进与完善,这门课程教学才更具有针对性和实效性。