提高T梁桥施工质量的细节工艺控制

T梁是重庆地区高速公路中小跨径桥梁中最常使用的结构型式,尤其是随着高速公路桥梁耐久性和舒适性的提高,先简支后连续的T梁得到了广泛应用。但是传统粗放的施工控制导致T梁预制经常存在一些质量问题,如结构尺寸偏差、预拱度偏差、保护层偏差以及外观质量的缺陷等,甚至因梁端的高差及对位偏差导致二次张拉效果降低,影响体系的二次转换。因此应重视梁体加工质量的重要性,从工程施工工艺细节进行精心控制。     

一体化的多模式公交票务系统

公共交通服务是整个城市服务体系中的一个重要组成部分,是城市交通可持续发展的一个重要环节。人们在城市内使用公共交通出行,需要有一个高效、便捷、舒适、经济的公共交通体系。在公共交通基础设施的建设之外,特别是在从制造业已经发展到了运营管理和服务理念等方面的背景下,公交票务系统也是一个相当重要的环节。该文借介绍法国克莱蒙地区多模式公交票务系统,在我国发展城市公共交通票务系统方面进行探讨。     

An analysis of the determinants of children’s weekend physical activity participation

This paper examines the out-of-home, weekend, time-use patterns of children aged 5–17 years, with a specific emphasis on their physical activity participation. The impact of several types of factors, including individual and household demographics, neighborhood demographics, built environment characteristics, and activity day variables, on physical activity participation is analyzed using a joint nested multiple discrete–continuous extreme value-binary choice model. The sample for analysis is drawn from the 2000 San Francisco Bay Area Travel Survey. The model developed in the paper can be used to assess the impacts of changing demographics and built environment characteristics on children’s physical activity levels.     

电动汽车复合驱动系统

电动汽车的复合驱动系统包括内燃机驱动和电力驱动，它综合了这两种驱动方式的优点。介绍了电动汽车的各种复合驱动结构，分析讨论了这些结构的优缺点，阐述了选择串联还是并联复合驱动结构时应考虑了主要问题，并给了一个单轴复合驱动结构的实例。     

前轮定位参数与轮胎特性对前轮摆振影响的研究

前轮定位参数对前轮摆振的影响是极其复杂的,它不仅影响了前轮的几何特性,并且对摆振系统的运动,约束与受力状况均产生重要影响。本文建立了包括全部前轮定位参数的前轮摆振数学模型;并在轮胎试验的基础上,比较系统、全面地研究了前轮定位参数对前轮摆振的影响规律。本文还研究了轮胎蛇形运动频率对汽车动力学摆振的影响。     

轮胎结构有限元分析应用于子午线轮胎帘线受力特性的研究

建立了195／60R14型子午线轮胎三维非线性有限元模型，研究了在静负荷作用下轮胎帘线的受力特征。结果表明，静负荷对轮胎接地区域内帘线受力影响显著；模型带束层结构为2层相交的帘线结构，不能构成力学上的对称；带束层角度的变化对帘线剪应力分布有一定的影响，对胎肩部位帘线剪应力影响较大。     

汽车空气悬架的现状展趋势

在相同的载荷作用下，空气弹簧可以得到比钢板弹簧低得多的振动频率，从而提高行驶平中性；空气弹簧具有变刚度特性，固有频率可以根据需要而适当地改变，由于其具有优良的性质，使得空气悬架在汽车悬架系统中的应用越来越广泛，在国外已渐渐发展成为标准装备，中对空气悬架的现状及发展趋势进行了阐述，同时分析了空气悬架的结构和工作原理，空气弹簧的特性及其在整车中的布置方式。     

Neuro-Fuzzy Control of a Tracked Vehicle Featuring Semi-Active Electro-Rheological Suspension Units

This paper presents vibration control of a tracked vehicle installed with electro-rheological suspension units (ERSU). As a first step, an in-arm type ERSU is designed, and its spring and damping characteristics are evaluated with respect to the intensity of electric fields. Subsequently, a 16 degree-of-freedom model for a tracked vehicle equipped with the proposed ERSU is established followed by the formulation of a neuro-fuzzy controller. This controller takes account for both ride quality and steering stability by adopting a weighting parameter between two performance requirements. The parameter is appropriately determined by employing a fuzzy algorithm associated with two fuzzy variables: the vertical speed of the body and the rotational angular speed of the wheel. Control performances to isolate unwanted vibration from bump and random road excitations are evaluated through computer simulations. In addition, maximum speed of the vehicle with 6 Watt power absorption is investigated with respect to the road roughness.