钻井液振动筛筛分建模及数值计算

利用流体力学的基本原理，研究筛网表面钻井液的流动特点。在综合筛箱运动、筛网倾角等参数对筛分影响的基础上，建立钻井筛的筛分模型，给出处理量的计算公式．探讨了运用均能原理和有限差分方法对筛分方程的求解，并编写处理量的数值计算程序．室内台架模拟试验结果表明，建立的筛分模型具有较高的计算精度．     

新能源发电系统低电压穿越测试用试验电网数学建模

在新能源发电系统低电压穿越（LVRT）测试时,需要研究试验电网的各种电压跌落故障特性及其对新能源发电系统的影响,因此需对试验电网数学建模并进行相关研究。文章在研究试验电网接线原理基础上,对试验电网数学模型进行了推导：并设计了电压跌落发生器的控制策略。仿真与试验结果验证了该数学模型的正确性和精确性。     

Analysis of Metropolitan Highway Capacity and the growth in vehicle miles of travel

A number of recent studies have examined the hypothesis of induced travel in an attempt to quantify the phenomenon (Hansen & Huang 1997; Noland, forthcoming). No study has yet attempted to adjust for potential simultaneity bias in the results. This study addresses this issue by the use of an instrumental variable (two stage least squares) approach. Metropolitan level data compiled by the Texas Transportation Institute for their annual congestion report is used in the analysis and urbanized land area is used as an instrument for lane miles of capacity. While this is not an ideal instrument, results still suggest a strong causal relationship but probably that most previous work has had an upward bias in the coefficient estimates. The effect of lane mile additions on VMT growth is forecast and found to account for about 15% of annual VMT growth with substantial variation between metropolitan areas. This effect appears to be closely correlated with percent growth in lane miles, suggesting that rapidly growing areas can attribute a greater share of their VMT growth to growth in lane miles.     

Swimming for survival: A role of phytoplankton motility in a stratified turbulent environment

We investigate a role for vertical migration in stratified coastal water, where the swimming speed is generally significantly less than the typical turbulent fluctuations in a tidally-mixed bottom layer. In our modelling approach we use a k- turbulence model to describe the physical forcing, a Lagrangian random walk model to describe the vertical displacement of individual cells in response to turbulence and due to cell motility, and a phytoplankton growth model to direct the swimming behaviour of the phytoplankton according to their light and nutrient requirements. The model results show how the cells form a stable subsurface chlorophyll maximum (SCM) at the base of the thermocline where episodic tidal turbulence causes erosion of part of the SCM biomass into the bottom mixed layer (BML). We then focus on the question of whether an ability to swim (weakly, compared to typical bottom layer turbulent intensities) provides any advantage by allowing return to the SCM. Our results show that tidal turbulence in the BML helps both motile and neutrally-buoyant cells by periodically pushing them into the base of the thermocline. Motile cells then have the advantage that they can swim further into the thermocline towards higher light which also reduces the likelihood of being re-mixed back into the BML.     

并联混合动力城市客车实际工况的试验与改进

提出一种针对城市客车工作模式的并联式混合动力驱动系统的机电耦合方案,并以燃油经济性为主要目标,在ECE（30）循环下设计该驱动系统的控制策略;基于ADVISOR2002建立该驱动系统的仿真模型,通过仿真和试验发现问题,并提出解决方案。     

微观仿真在城市停车设施规划中的应用

为研究停车场规划和可达性对城市路网的影响,在世界范围内的三个不同城市应用微观仿真模型模拟停车设施规划。描述了三个城市采用的不同研究方法及得到的研究结果。三项研究都试图找到由驾驶人寻找停车位而造成的城市交通拥堵的解决方法。同时,在测试设计方案时,都使用了S-Paramics微观仿真模型。     

Modelling of motorised two-wheelers: a review of the literature

Motorised two-wheeler (MTW) has emerged as the most widely used transportation mode for short distance trips in many Asian and European countries because of its affordable price and flexibility in manoeuvring through traffic. Its small size and aggressive riding patterns can considerably affect the overall traffic flow characteristics and safety. Modelling the characteristic behaviour and complex movement patterns of motorised two-wheelers is essential due to their pronounced role in microscopic traffic simulations, traffic management strategies, safety evaluation, transport planning and intelligent transportation systems. This paper begins with an overview of the determinant factors used for MTW modelling, followed by a critical review of various modelling approaches that have been adopted to depict the movement patterns of MTWs. The review concentrates on (i) identifying the factors mostly studied with respect to MTW-research, (ii) discussing the potential and limitations of each modelling approach and (iii) reporting some of the aspects that need further consideration for modelling MTWs in heterogeneous mixed traffic streams. The findings of the paper suggest that an integrated approach can be more viable to depict the unique riding patterns of motorised two-wheelers and some possible directions for future studies are also proposed.     

A simulation tool for bicycle sharing systems in multimodal networks

This paper presents a methodology for modelling an urban transport system, integrating public bicycles in a multi-modal network. A bike cost function that reproduces the effect of slopes on cycling speeds is proposed. Also, the effect of traffic levels on the attractiveness of cycling routes is taken into account. The model applies the modal split and network assignment phases in a multimodal network with different classes of users. It has been verified over a test network and then validated by applying it to a real case in the city of Santander in Spain. The results obtained make this model a useful decision-making tool to encourage the use of the public bicycle from a sustainable development point of view.     

船舶复杂轴系扭转振动建模及动力学分析

针对船舶复杂轴系结构,提出一种基于能量法的轴系扭转振动建模及动力学分析方法。该方法对船舶复杂轴系中的典型结构进行统一能量化描述,如联轴器、齿轮、负载等,并结合弹性轴的能量函数构建轴系结构的拉格朗日能量泛函;然后,利用最小二乘法和广义变分法,对轴系角位移展开项系数进行求解,从而建立适用于船舶复杂轴系结构的扭转动力学模型。通过与有限元方法计算结果相比较来验证该建模方法的准确性,并利用该方法分析连接刚度和负载转动惯量对整体轴系扭振特性的影响,以期为船舶复杂轴系设计提供一定参考。