Engineering-Based Decisions in Construction

This paper uses four case studies to emphasize the fact that field engineering decisions cannot be made without a full understanding of all the technical problems involved. Two of the studies are taken from conventional design-bid-build projects and two are taken from design-build projects in which the ability to strongly influence design in the interest of construction efficiency places a new and increased emphasis on construction and field engineering skills. The cases also show that field engineering decisions frequently address new and unexpected realities, changed conditions, and transient loads, and thus they require high levels of understanding, technical analysis, and creative thought. We emphasize the need for universities and construction engineering programs to develop graduates who are capable of integrating design and construction considerations throughout the project delivery process. We also urge programs to continue to focus strongly on field engineering as the foundation for success in an increasingly complex and technically driven construction industry.     

Strategic thinking and stress

In this study we investigate the behaviour and the performance of experimental subjects, who had to solve a series of tasks of ‘strategic thinking’ under a stress and a non-stress condition. No significant differences between the conditions could be found with respect to performance and improvement of performance within the series of tasks, but the experimental subjects exhibited under the different conditions different forms of behaviour. Unexpectedly the Ss working under the stress-condition exhibited a more ‘analytical’ behaviour and increased their workload, instead of decreasing it. Additionally they exhibited a tendency for measures with salient effects and proved to be better in finding the right points of main effort. The results are discussed with respect to a general theory of action regulation.     

模糊层次分析法在无线个域网协同传输中的应用

在无线个域网中,利用多终端进行协同传输可以很好地改善系统的吞吐量,提高传输速率。针对无线个域网协同传输中的终端选择问题,提出了一种基于模糊层析分析法的多属性决策算法。该算法使用终端接入点的信号接收强度、可用带宽和时延等多种属性计算终端性能,能够选择性能较好的多个终端进行协同传输。仿真表明,该算法能够选择出合理的、性能较优的终端进行协同传输,有效地提高了系统的吞吐量。     

Network selection based on multiple attribute decision making and group decision making for heterogeneous wireless networks

One of the key issues for radio resources management is network selection strategy in heterogeneous scenarios.In order to provide ubiquitous service,the paper puts forward a network selection algorithm based on multiple attribute decision making(MADM) and group decision making(GDM).Firstly,the proposed algorithm acquires attribute weights’ vectors of the subjective and objective decision makers based on MADM,and then the two attribute weights’ vectors are synthesized to be a new attribute weights’ vector by using GDM.Considering that the results of GDM should be reasonable and convincible,the criterion of consistency is adopted for judging the compatibility of group judgments.More specifically,the algorithm takes into account not only objective attributes of networks but also the preference of subscribers and traffic class.Hence it guarantees that the subscribers can not select the networks with poor performance depending on their preference.The simulation results show that the proposed algorithm can effectively reduce the handoff number and provide subscribers with satisfactory quality of service(QoS).     

Optimal Scheduling of Utility Electric Vehicle Fleet Offering Ancillary Services

Vehicle‐to‐grid presents a mechanism to meet the key requirements of an electric power system, using electric vehicles (EVs) when they are parked. The most economic ancillary service is that of frequency regulation, which imposes some constraints regarding the period and duration of time the vehicles have to be connected to the grid. The majority of research explores the profitability of the aggregator, while the perspective of the EV fleet owner, in terms of their need for usage of their fleet, remains neglected. In this paper, the optimal allocation of available vehicles on a day‐ahead basis using queuing theory and fuzzy multi‐criteria methodology has been determined. The proposed methodology is illustrated on the daily scheduling of EVs in an electricity distribution company.     

网上购物系统的工程心理学设计因素

在影响网上购物发展的诸多因素当中,网上商店的信息结构、界面与交互方式等工程心理学因素一直是容易被人忽视而又是十分重要的因素,它是造成购物者不满意购物经验的重要因素,因为购物者要在网上商店里众多而纷杂的商品信息中寻找所要求的信息不太容易,从而难以实现网上购物,并产生较大的负面效果。并且实际应用中也缺乏必要的对网上购物系统相关工程心理学因素的系统分析与理解。本文依据工程心理学的主要原理,从用户特征、购物任务、信息环境三个方面分析可能对网上商店设计产生重要影响的主要因素,以期增进对网上购物的交互与设计的理解。     

用DCG制作全息显示屏的工艺研究

本文对应用ＤＣＧ制作全息显示屏的工艺进行了实验研究,从中比较出最佳的制版工艺,优选出满足课题要求的拍摄光路,并讨论了后处理工艺对全息显示屏质量的影响,最后还提出了一些尚待解决的问题。     

Autonomous terrain-following for unmanned air vehicles

This paper presents an integrated guidance and control design scheme for an unmanned air vehicle (UAV), and its flight test results. The paper focuses on the longitudinal control and guidance aspects, with particular emphasis on the terrain-following problem. An introduction to the mission, and the terrain-following problem is given first. Waypoints for climb and descent are defined. Computation of the reference trajectory in the vertical plane is discussed, including a terrain-following (TF) algorithm for real-time calculation of climb/descent points and altitudes. The algorithm is particularly suited for online computation and is therefore useful for autonomous flight. The algorithm computes the height at which the vehicle should fly so that a specified clearance from the underlying terrain is always maintained, while ensuring that the vehicle’s rate of climb and rate of descent constraints are not violated. The output of the terrain-following algorithm is used to construct a smooth reference trajectory for the vehicle to track. The design of a robust controller for altitude tracking and stability augmentation of the vehicle is then presented. The controller uses elevators for pitch control in the inner loop, while the reference pitch commands are generated by the outer altitude control loop. The controller tracks the reference trajectory computed by the terrain-following algorithm. The design of an electromechanical actuator for actuating the control surfaces of the vehicle during flight is also discussed. The entire guidance and control scheme is implemented on an actual experimental vehicle and flight test results are presented and discussed.