Parameters optimisation of a vehicle suspension system using a particle swarm optimisation algorithm

The purpose of this paper is to determine the lumped suspension parameters that minimise a multi-objective function in a vehicle model under different standard PSD road profiles. This optimisation tries to meet the rms vertical acceleration weighted limits for human sensitivity curves from ISO 2631 [ISO-2631: guide for evaluation of human exposure to whole-body vibration. Europe; 1997] at the driver's seat, the road holding capability and the suspension working space. The vehicle is modelled in the frequency domain using eight degrees of freedom under a random road profile. The particle swarm optimisation and sequential quadratic programming algorithms are used to obtain the suspension optimal parameters in different road profile and vehicle velocity conditions. A sensitivity analysis is performed using the obtained results and, in Class G road profile, the seat damping has the major influence on the minimisation of the multi-objective function. The influence of vehicle parameters in vibration attenuation is analysed and it is concluded that the front suspension stiffness should be less stiff than the rear ones when the driver's seat relative position is located forward the centre of gravity of the car body. Graphs and tables for the behaviour of suspension parameters related to road classes, used algorithms and velocities are presented to illustrate the results. In Class A road profile it was possible to find optimal parameters within the boundaries of the design variables that resulted in acceptable values for the comfort, road holding and suspension working space.     

移动模架造桥机在苏通大桥引桥PC连续梁的应用

介绍了苏通北引桥完全自行式移动模架系统的一般构造及工作原理。重点分析了移动模架系统施工过程中箱梁底板线形控制要点及箱梁悬臂段受力特点，针对悬臂端箱梁底板横向应力水平过高的特点，揭示了原因，提出了工程措施并在实桥中应用。     

脉宽调制逆变器—异步电动机系统电压,电流的计算机模拟

交—直—交电压型脉宽调制逆变器是牵引领域中很有发展前途的一种逆变器。本文对该种逆变器—异步电动机系统建立了一个通用的数学模型,它具有运算速度快、精度高及对计算机内存容量要求低的特点。从原则上来说可在系统的整个调频范围内,在微型计算机上对任何稳态工况时的逆变器输出电压、电机定、转子电流的基波及谐波分量进行分析,从而为该种系统的研制和改进提供了一个有力的工具。     

电控气缸注油器注油调频控制机理分析

为实现电控气缸注油器的注油调频控制,探究其注油调频的计算方法,提出注油调频的通用计算公式,分析该计算公式在研发电控气缸注油器注油调频机理上的适用方法。     

The Downs–Thomson Paradox with responsive transit service

Downs (1962) and Thomson (1977) suggested that highway capacity expansion may produce counterproductive effects on the two-mode (auto and transit) transport system (Downs–Thomson Paradox). This paper investigates the occurrence of this paradox when transit authority can have different economic objectives (profit-maximizing or breakeven) and operating schemes (frequency, fare, or both frequency and fare). For various combinations of economic objectives and operating schemes, the interaction between highway expansion and transit service is explored, as well as its impact on travelers’ mode choices and travel utilities. Further, for each combination, the conditions for occurrence of the Downs–Thomson Paradox are established. We show that the paradox never occurs when transit authority is profit-maximizing, but it is inevitable when the transit authority is running to maximize travelers’ utility while maintaining breakeven. This is because the former transit authority tends to enhance transit service (e.g., raise frequency or reduce fare) when facing an expanded highway; and on the contrary, the latter tends to compromise transit service (e.g., reduce frequency or raise fare). Both analytical and numerical examples are provided to verify the theoretical results.     

二层线性规划的模糊数学解法(Ⅱ)

针对上层有约束条件、下层有Ｎ个独立的决策单元的二层线性规划问题，提出了一种模糊数学解法。首先，把这种规划分解为若干单层规划；然后引入隶属函数，用３个定理对各单层规划的解进行讨论，最终把这种二层线性规划转化为求解一个单层线必规划问题。使问题得到了简化。     

Surface patterns of zooplankton spatial variability detected by high frequency sampling in the NW Mediterranean. Role of density fronts

High frequency sampling was performed in daylight hours along a 35 km transect in the Ligurian Sea to investigate the upper layer zooplankton distribution during the spring phytoplankton bloom. The results show detailed spatial structure and biomass of key zooplankton functional groups, copepods, salps and krill larvae, within the different water masses characterizing this region. Although observed values of total copepod biomass distribution were rather constant along the transect, species-specific patterns were observed in the copepod spatial distribution. The larger species Calanus helgolandicus, as well as Centropages typicus, Oithona spp., and Oncaea spp., were associated with the frontal zone. However, Acartia spp. had a scattered distribution, and Clausocalanus/Paracalanus did not have a clear pattern. In addition, krill larvae were concentrated in the frontal area and salps had a scattered pattern. The cross-shore zooplankton distribution appeared strongly influenced by both the Northern Ligurian current governing inshore waters, which acts as a major flushing forcing, and the Ligurian front, which governs offshore waters and may act as retention area for zooplankton.     

直线电机在城市轨道交通中的优势及应用

直线电机轮轨交通系统因其工程造价低、线路适应性强等优势，被认为是资源节约型城市轨道交通先进模式。分析了日本、加拿大等直线电机地铁车辆的转向架、牵引和制动等技术的特点和性能，探讨了直线电机在城市轨道交通应用中的经济性和适用性。     

柴油机曲轴速度变化的频谱分析

使用光电转速传感器,通过计算其感应器内部时钟的脉冲测量曲轴的速度变化,分析低谐波转速变化能过滤出由曲轴的动力响应产生的失真,根据这些谐波携带的信息建立起测量数据和发动机平均气压转矩之间的关系,从而发现故障并且确定不良的气缸.