基于混沌粒子群算法的多目标调度优化研究

针对当前车间调度多目标优化研究存在收敛速度慢、精度低的问题,提出了混沌多目标粒子群优化算法。在算法中,设计了一种新的叠加Logistic扰动的Tent混沌映射算子,通过该算子周期性地更新种群以保证种群的多样性;对收缩粒子群算法进行了扩展使其能够快速收敛到Pareto前沿。通过标准测试问题与实际应用对所提方法进行了验证,实验结果显示混沌多目标粒子群优化算法无论在收敛速度还是在优化精度上都优于其它典型多目标进化算法。     

Heaving response of a large floating platform

In this paper, we tackle a new dynamic problem of a large floating platform in a heaving harmonic motion due to 9000 performers or people simultaneously jumping in mass events. The objective is to estimate the heaving response of the floating structure so as to establish whether the participants will be at ease during their performances. By assuming the platform as a rigid body, the added mass and the radiation damping coefficient are first estimated. This requires the evaluation of a three-dimensional velocity potential governed by Laplace’s equation. The Green's function method was used to solve the boundary value problem. Based on the estimated added mass and radiation damping, we employ the finite element software NASTRAN to solve the transient dynamic problem for the displacement and acceleration responses. The impulse force used for the transient problem is based on experimentally obtained ground reaction force (due to a human jumping) as measured by using a force plate. As the floating platform may be dismantled and reconfigured into other shapes, two different sizes of floating platform as well as different number of jumps were considered in this study.     

Research on floating wind turbines: a literature survey

This article presents a literature survey of research and development on floating wind turbines. The various, proposed conceptual designs for floating platforms used for floating wind turbines are described and the working principles of these various floater concepts are outlined. This is followed by an overview of the research work that has been undertaken pertaining to floating wind turbine technology by several research institutes and the academic community. The research work undertaken to date is reviewed categorically according to the proposed floater concept (spar-buoy type, TLP type, semi-submersible type, pontoon type and others) as per sections 3–7. Based on the research work undertaken thus far, recommendations for future work are suggested.     

地铁运营线路既有普通扣件地段更换谐振式浮轨扣件施工工艺

本文以地铁施工中的轨道工程施工为背景,介绍如何在地铁运营线路既有普通扣件地段更换谐振式浮轨扣件。     

The frequency of CFVD speed report for highway traffic

The control signals of cellular networks have been used to infer the traffic conditions of the road network. In particular, consecutive handover events are being used to estimate the traffic speed. During traffic congestion, consecutive handover events may be rare because vehicles move slowly, and thus very few or no speed reports would be generated from the congested area.However, the traffic speed report rate during traffic congestion has not been investigated in the literature. In this paper, we present an analytic model to estimate the speed report rate from cellular network signaling in steady traffic conditions, that is, the traffic speed and flow are assumed constant. Real field trial data were used to validate our analytic model. In addition, computer simulations were conducted to study how speed reports are generated in dynamic traffic conditions when traffic speed and flow change rapidly. Our study indicates that in a typical cell of length 1.5 km with a typical expected call holding time of 1 min, no speed report was generated from a congested three‐lane highway. Our study demonstrates that the lack of speed reports from consecutive handover events during rush hours indicates severe traffic congestion, and new methods that can estimate traffic speed from cellular network data during severe traffic congestion need to be developed. Copyright © 2013 John Wiley & Sons, Ltd.     

Planning for population ageing: Ensuring enabling and supportive physical-social environments – Local infrastructure challenges

Ensuring enabling and supportive environments is a key global priority in planning for population ageing. This paper examines the challenges local governments face in creating age-friendly physical-social environments. Findings from a recent study of local government and ageing in New South Wales, Australia and subsequent research are reported. The analysis reveals that local councils have differing abilities to provide age-friendly local infrastructure. Challenges are greater overall for regional, rural and fringe councils compared to metropolitan. Timely provision is greatly constrained by insufficient resources, the large scale of the task and the low priority accorded, despite the immediate need for action. A pressing requirement is demonstrated for local councils to give primacy to population ageing in their long-term strategic, asset and financial planning, and to engage in reform measures to assist in financing the cost.     

高剪切力下气泡聚并与破碎特性的数值研究

了解气泡在剪切力场中的聚并与破碎机理及生长与运动特性,对于气液搅拌槽中桨叶的优化设计具有重要意义。将欧拉-欧拉模型与群体平衡模型(population balance model, PBM)进行耦合,对不同剪切力下的气液两相流场进行求解,研究了剪切力、高剪切力下进气速度、气泡塔高度对气泡聚并与破碎的影响,并结合气泡的聚并与破碎模型对高剪切力下气泡的聚并与破碎机理进行了探究。研究表明,剪切力主要影响气泡的破碎,当剪切力较小时其对气泡破碎的影响较小,随着剪切力的增大其对气泡破碎的影响逐渐显著,使小气泡的含量大幅增多;高剪切力下进气速度、气泡塔高度对气泡的聚并与破碎的影响不明显。     

变母体产品可靠性评估方法

产品在不同阶段的技术状态是有差异的,因此在可靠性评估时不能视为同一母体,其试验数据也不能做简单的累加处理。由于试验次数较少,在进行可靠性评估时,评估值往往低于应达到的实际值。本文将各阶段的可靠性作为一个整体来研究,建立了可靠性增长评估的数学模型,导出了成败型可靠性评估方程,给出了评估方法,该方法充分利用各研制的试验信息,反映了研制产品的可靠性增长过程,为多研制阶段、变母体、试验数据较少的产品可靠性验证,提供了有效的评估途径,同时以产品数据为例计算了应达到的实际可靠性水平,计算结果表明,评估结果与产品应达到的可靠性水平基本相同。