钢吊箱整体起吊时力学性能分析

钢吊箱整体起吊是钢吊箱施工中的一个重要阶段,为了确保其安全性,需对钢吊箱在整体吊装阶段的力学性能进行全面分析。首先分析了钢吊箱在整体吊装阶段需要考虑的计算工况,然后通过建立有限元模型,对两种不同形状钢吊箱整体起吊时的力学性能进行了全面分析,结果表明:钢吊箱结构整体构造合理,但局部应力集中较严重,椭圆形钢吊箱可以不设钢管支撑和支撑桁架,对于风和水流的阻力系数小,因此,宜优先采用椭圆形钢吊箱。     

大掺量磨细矿渣粉高性能混凝土的试验研究

论述了大掺量磨细矿渣粉对混凝土性能的影响,研究结果表明:用S95磨细矿渣粉和少量粉煤灰可以配制出早期抗裂性和耐久性均好的C50~C70高性能混凝土,84 d氯离子扩散系数均小于1.50×10-12m2/s;大掺量磨细矿渣粉高性能混凝土的收缩徐变较普通混凝土小。     

烘烤硬化钢板BH340与普通冷轧钢板St13性能对比分析

通过试验对汽车用高强度冷轧钢板BH340的力学性能、成形性能和烘烤硬化性能进行了全面研究,并与St13的各项性能进行了比较.结果表明,烘烤硬化钢板BH340在力学性能、烘烤硬化性能等方面均优于St13,成形性能不低于St13.     

PG70-22改性沥青在工程中的应用研究

结合空军中原A机场跑道整修工程的实践，对PG70－22科氏改性沥青及其混合料的性能特点进行了系统评价，并对工程应用中值得注意的问题进行了全面的分析总结。     

增压柴油机燃用LPG/柴油双燃料的性能研究

对IVECO索菲姆增压柴油机改装为LPG/柴油双燃料发动机进行了试验研究。结果表明 ,采用机电联合控制方式 ,双燃料发动机与原柴油机相比 ,动力性基本相同 ,排放烟度有大幅度改善 ,但CO ,HC ,NOx 排放都有不同程度的提高     

湿式离合器出油口甩出油温度预测方法

为了实现对湿式离合器出油口甩出油温度传感器的冗余校验和自我诊断，提出了一种基于粒计算约简的离合器出油口甩出油温度的模糊预测方法。首先分析出油口甩出油温度的影响因素，将主要影响因素作为预测输入量，并采用模糊推理理论预测当前离合器出油口甩出油温度。在设计模糊预测方法的过程中，通过分析实车数据得到车辆行驶时离合器处于高滑摩功率过程和低滑摩功率过程的不同特性，分别确定相对应的隶属度函数和模糊预测规则，从而进一步提高出油口甩出油温的预测精度。为了提高模糊预测算法的实时性，基于模糊预测规则创建模糊决策表，模糊输入量和模糊输出量分别作为决策表的条件属性集与决策属性集。利用粒计算理论对模糊决策表的条件属性集进行属性约简，通过削减冗余信息有效降低模糊输入量和模糊预测规则的个数。最后利用实车采集的数据对比分析约简前后模糊预测算法的单步运行时间和预测误差等性能指标。试验结果表明：基于粒计算约简的模糊预测算法能够有效保障预测精度，同时拥有更少的模糊预测规则数和模糊输入量，有效解决了模糊预测算法占用资源较多以及实用性较差的问题。     

The perception of Bus Rapid Transit: a passenger survey from Beijing Southern Axis BRT Line 1

Bus Rapid Transit (BRT) has emerged as a cost-effective transport system for urban mobility. As a relatively new form of Mass Transit, its ability to provide a high-quality transport service and potential to stimulate land development remain largely unexplored. This study intends to investigate the public attitude towards BRT services, as well as respondents’ perception of living near BRT stations, using the Beijing Southern Axis BRT system as a case study. A data-set of responses to 525 questionnaires were assembled and analysed using a combination of statistical techniques. The results show that BRT has gained great popularity among passengers, and brought about a positive impact on the attractiveness of residential property. The data identify that the majority of passengers are work-related commuters and use BRT more than once a day. The captive users have a higher satisfaction than choice users with respect to reliability, comfort & cleanliness and overall satisfaction with the BRT service. It is argued that the BRT has significantly improved the attractiveness of residential property along the BRT corridor.     

跨径对水泥混凝土桥面铺装力学性能影响的数值分析

水泥混凝土桥面铺装力学计算分析中,桥梁跨径对铺装层力学响应有重要影响。文章针对跨径长短对桥面铺装力学性能指标的影响展开研究,为桥面铺装力学计算中模型的简化提供理论依据。     

不同钢内衬加固钢筋混凝土管涵力学特性试验研究

为研究不同钢内衬加固钢筋混凝土管涵的加固效果及其力学特性,对不加固的钢筋混凝土管、10 mm厚平钢管内衬加固钢筋混凝土管、波纹钢管内衬加固钢筋混凝土管3个试件进行两点加载试验,测试P—Δ曲线及截面应变。试验结果表明:采用直接加固方式时,波纹钢管内衬加固钢筋混凝土管、平钢管内衬加固钢筋混凝土管的极限承载力分别比未加固圆管的极限承载力提高240%、22%;加固形成的钢筋混凝土—内填混凝土—内衬波纹钢管截面为部分组合截面;钢筋混凝土—内填混凝土—内衬平钢管截面接近非组合截面,其受力过程与未加固管截面受力过程相似。     

Roll- and pitch-plane coupled hydro-pneumatic suspension

Passive fluidically coupled suspensions have been considered to offer a promising alternative solution to the challenging design of a vehicle suspension system. A theoretical foundation, however, has not been established for fluidically coupled suspension to facilitate its broad applications to various vehicles. The first part of this study investigates the fundamental issues related to feasibility and properties of the passive, full-vehicle interconnected, hydro-pneumatic suspension configurations using both analytical and simulation techniques. Layouts of various interconnected suspension configurations are illustrated based on two novel hydro-pneumatic suspension strut designs, both of which provide a compact design with a considerably large effective working area. A simplified measure, vehicle property index, is proposed to permit a preliminary evaluation of different interconnected suspension configurations using qualitative scaling of the bounce-, roll-, pitch- and warp-mode stiffness properties. Analytical formulations for the properties of unconnected and three selected X-coupled suspension configurations are derived, and simulation results are obtained to illustrate their relative stiffness and damping properties in the bounce, roll, pitch and warp modes. The superior design flexibility feature of the interconnected hydro-pneumatic suspension is also discussed through sensitivity analysis of a design parameter, namely the annular piston area of the strut. The results demonstrate that a full-vehicle interconnected hydro-pneumatic suspension could provide enhanced roll- and pitch-mode stiffness and damping, while retaining the soft bounce- and warp-mode properties. Such an interconnected suspension thus offers considerable potential in realising enhanced decoupling among the different suspension modes.