罕遇地震作用下高速铁路减隔震简支梁桥合理计算模型的探讨

以往在分析减隔震桥梁的地震响应时,由于考虑到桥墩和基础应保持弹性工作状态,在基于强度的设计中偏于安全考虑桥墩一般采用毛截面刚度建立弹性梁单元模型。实际上,在罕遇地震作用下,桥墩墩底截面虽然未达到屈服状态,仍然会出现保护层混凝土开裂,并导致桥墩刚度降低。此时,应考虑对桥墩刚度进行适当修正以估计桥梁的各项地震响应参数,这也有利于实现减隔震桥梁基于位移的抗震设计。结合西部高速铁路中典型的简支梁桥结构形式,分别采用弹塑性纤维梁柱单元、弹性梁柱单元、考虑刚度修正的弹性梁柱单元模拟桥墩建立3种计算模型,探讨适用于罕遇地震作用下的高速铁路减隔震桥梁的合理计算模型。结果表明,当罕遇地震作用下桥墩位移延性超过0.5时,考虑刚度修正的弹性梁柱单元模拟桥墩的计算模型能够较好地估计桥梁各项地震响应参数。     

用于智能驾驶系统评价的乘员损伤模型

只有较少的交通事故数据资源被用于建立基于碰撞速度信息的乘员损伤模型，致使所得到的模型精度差。为此，提出了基于车辆变形深度的乘员损伤模型。对美国不同制造年代和车辆级别的事故数据进行聚类分析，论证出车辆变形深度与乘员损伤风险具有相关性。以车辆变形深度为自变量，通过回归分析得到乘员损伤模型。不同种类车辆的乘员损伤模型拟合精度R²约为0.9，证明了该模型的正确性。为进一步验证，以此模型为基础，评价智能驾驶系统的有效性。以自动紧急制动系统为例，对比基于变形深度和速度变化量信息2种方法的有效性计算结果。结果表明：2组结果的平均误差不超过1%，验证了基于变形深度的乘员损伤模型的准确性。该模型仅需要事故数据库中准确的变形深度信息，能够获得更多的事故数据支持，从而可以更好地适应于不同类别智能驾驶系统的评价需求。     

学院教职工付酬方案的最优化控制系统

利用线性优化理论和教学建模方法，对学院教职工最优化付酬方案进行了研究了最优化分配教职工报酬的控制模型，为主管部门提供了强有力的参考。     

九圩港闸闸下兴建桥梁工程模型试验研究

九圩港闸下新建桥梁工程，不能单独从泥沙问题来考虑其影响，还应考虑工程后对九圩港闸引、排水功能以及对闸上已有桥梁工程的影响。通过物理模型试验研究将较好地解决相关难题，为工程决策、设计提供科学依据。研究结果表明，桥梁工程方案实施后潮位最大壅高0．028m，对流速影响较大的范围在桥轴线上下100m之内，对九圩港闸引、排水流量的影响在3％以内。     

Development and validation of a direct mode choice model

A direct discrete mode choice model is introduced using relative attributes of competing modes as well as socioeconomic characteristics of travelers. The model is calibrated and validated for two available historic databases in the Dallas–Fort Worth region. The validation is conducted against the outputs of a current nested logit model used by the regional planning organization as well as the observed values based on transit ridership surveys for a newly inaugurated commuter rail service. The calibrated model is applied after the introduction of this new transit mode. The results show that the estimated mode shares by the proposed model have a statistically better consistency with the observed values than the estimates of the conventional nested logit model. Unlike the logit model, the structure of the direct model based on relative attributes also has the advantage of not needing recalibration each time a new travel mode is introduced. The model is found to be easier to calibrate and produces more accurate results than the nested logit model, commonly used by many metropolitan planning organizations.     

Multi-objective control of a full-car model using linear-matrix-inequalities and fixed-order optimisation

This paper studies multi-objective control of a full-vehicle suspension excited by random road disturbances. The control problem is first formulated as a mixed ?₂/?_∞ synthesis problem and an output-feedback solution is obtained by using linear-matrix-inequalities. Next, the multi-objective control problem is re-formulated as a non-convex and non-smooth optimisation problem with controller order restricted to be less than the vehicle model order. For a range of orders, controllers are synthesised by using the HIFOO toolbox. The efficacy of the presented procedures are demonstrated by several design examples.     

The IMMa optimisation algorithm without control input parameters

The IMMa optimisation algorithm (IOA) consists of a heuristic method based on a differential evolution algorithm for choosing the Magic Formula (MF) tyre model parameters. In a previous paper, we demonstrated that the IOA improved the searching procedure of optimum MF parameters with respect to the starting value optimisation (SVO) methods. But we had to introduce some control input parameters that were fixed during the running process. Now, the new version does not require control input variables to be chosen by the user. That is, we use an algorithm with self-adapting control parameters and it continues being easy to use, robust and fast. Hence, users do not need any kind of knowledge to use the IOA.     

基于计算模型运用Civil3D实现路网场地整体优化的设计方法

提出基于条件极值的场地标高计算模型,采用该模型进行场地设计可实现地块与地块之间、地块与道路之间的土石方总体最优。通过工程实例介绍应用Civil3D实现该模型的场地设计方法,该方法效率较高,适用面较广,适合各种情况下的园区场地设计。     

Dynamic model for ride comfort evaluations of the rubber-tired light rail vehicle

The dynamic model was developed to evaluate vibration accelerations and ride comforts during the running of the Korean-standardised rubber-tired light rail vehicle. Ride comfort indexes were analysed and tested in accordance with UIC 513R by using the dynamic model and the actual vehicle in the test track. Based on the comparisons between analysis results and test results, the validity of the developed dynamic model was evaluated. It was verified whether or not the developed Korean-standardised rubber-tired light rail vehicle met the specified target specification on ride comfort. In addition, the influence of the wearing of guide wheels on ride comfort was estimated.     

An insight into linear quarter car model accuracy

The linear quarter car model is the most widely used suspension system model. A number of authors expressed doubts about the accuracy of the linear quarter car model in predicting the movement of a complex nonlinear suspension system. In this investigation, a quarter car rig, designed to mimic the popular MacPherson strut suspension system, is subject to narrowband excitation at a range of frequencies using a motor driven cam. Linear and nonlinear quarter car simulations of the rig are developed. Both isolated and operational testing techniques are used to characterise the individual suspension system components. Simulations carried out using the linear and nonlinear models are compared to measured data from the suspension test rig at selected excitation frequencies. Results show that the linear quarter car model provides a reasonable approximation of unsprung mass acceleration but significantly overpredicts sprung mass acceleration magnitude. The nonlinear simulation, featuring a trilinear shock absorber model and nonlinear tyre, produces results which are significantly more accurate than linear simulation results. The effect of tyre damping on the nonlinear model is also investigated for narrowband excitation. It is found to reduce the magnitude of unsprung mass acceleration peaks and contribute to an overall improvement in simulation accuracy.