深圳地铁11号线橡胶弹簧浮置板轨道动力仿真及测试

深圳地铁11号线是国内首次采用橡胶弹簧浮置板轨道的地铁线路。为确保该种浮置板结构的安全性、检验其减振效果,有必要针对其动力学特性进行全面的仿真和测试。首先,通过模态分析、谐响应分析考察其固有频率、振动传递特性;然后建立车辆-轨道耦合动力学模型,对其减振效果、动态位移进行仿真模拟;最后通过实车测试,全面检测其减振效果、动态位移,以及轮轨力、脱轨系数、轮重减载率等各项动力学指标。相关理论分析及实测结果表明:橡胶弹簧浮置板固有频率为10. 5 Hz,可明显削弱频率在18 Hz以上的振动,其减振效果达13～15 d B,满足设计要求;轮轨垂向力、轮轨横向力均略小于同等条件下的普通整体道床;脱轨系数、轮重减载率均满足规范要求。以上理论研究和实践表明:橡胶弹簧浮置板结构安全、减振效果好,各项动力学指标优良,是一种较为理想的轨道减振设施。     

CNG船舶运输新技术应用研究

针对当前国际能源市场的发展态势，本文对呼声最高的石油替代产品-天然气的最新运输技术进行了深入分析.通过与液化天然气（LNG）等运输方式的比较，指出由于压缩天然气（CNG）运输成本低、安全便捷的突出特点，CNG船舶运输必将成为天然气中、小储量运输和短距离海上运输的最佳运输方式。     

传动轴弯曲固有频率理论计算方法研究

随着我国社会的快速发展,人们生活水平的提高,司乘人员对商用车的驾乘舒适性要求越来越高,商用车越发关注整车NVH性能。文章主要介绍与传动轴振动密切相关的弯曲固有频率的理论计算方法,并将理论计算结果与台架试验、CAE结果做比较,说明理论计算结果的准确性。     

基于Prescan的自然驾驶场景构建与研究

文章主要描述基于Prescan软件对实车的自然驾驶场景片段转换成虚拟场景,用于ADAS或自动驾驶模拟测试.通过配备毫米波雷达、相机、Mobileye摄像头等传感器采集道路驾驶数据,提取场景片段,转化成虚拟软件中相应的实车场景,用于HIL或MIL测试,可实现重复性测试,降低测试成本,模拟恶劣天气等状况,复现实车测试状态等...     

Estimation of natural frequencies and damping using dynamic field data from an offshore wind turbine

The dynamic characteristics of offshore wind turbines are heavily affected by environmental loads from wave and wind action and nonlinear soil behaviour. In the design of the monopile structures, the fatigue load due to wind and wave loading is one of the most important problems to consider. Since the fatigue damage is sensitive to the foundation stiffness and damping, increasing the accuracy of analysis tools used in the design and optimization process can improve the reliability of the structure and reduce conservatism, thereby leading to a more cost-efficient design. In this context, analysis of field data is important for calibrating and verifying purposes. This paper presents analysis of measured accelerations and strains from a wind farm in the North Sea with monopile foundations. Field data during idling conditions, collected over long periods of operation, are analysed and the natural frequencies are determined, and damping is estimated. The measured natural frequencies are compared to calculated values using an aero-servo-hydro-elastic code, showing a good agreement in the frequency range below 2 Hz. Variation of the natural frequencies with intensity of loading may indicate effect of soil nonlinearity on the overall OWT response. Since the first natural bending modes have the largest potential to mobilize soil reactions, they are of primary interest in this context. The effect of load (wave, wind and dynamic bending moment) on the first natural frequency is investigated using different analysis techniques in the frequency domain and time domain. A clear correlation between load level and first natural frequency is demonstrated. A simple nonlinear SSI model of the tower/soil system is employed to numerically investigate the observed changes in the measured first natural frequency with the level of loading and increased overall damping. The simulated results reproduce the general trends in the observed reduction in the first natural frequency and increased damping ratio with the load level. However, the effect of the load level is less than that observed in the measurements, indicating contribution also from other factors than soil nonlinearity.     

公路绿化设计要与公路自身特点和自然环境协调一致

论述了新时期公路绿化美化设计新概念,重点阐述了公路绿化美化与公路自身特点和自然环境相协调的重要性,突出了和谐绿化、综合绿化的功能和效果,对提高公路绿化水平起到了积极推动作用。     

特长公路隧道通风设计若干问题与对策

目前,我国在特长公路隧道的通风设计中,在隧道自然风阻力计算、根据稀释烟雾计算隧道需风量、送排式通风系统中“不应有短道回流”和通风斜井倾角选用等方面存在一定的问题。文章在对问题进行分析论证的基础上提出:(1)隧道自然风阻力应由自然风等效压差确定,在缺少工程实地观测资料的情况下,假定隧道自然风阻力为常量,并在10~30 Pa之间取值;(2)依据稀释烟雾计算隧道需风量时,在公式中应引入烟雾的质量浓度或烟雾的体积浓度,并用其替代公式中的一般烟雾浓度;(3)竖井送排式通风系统中宜变短道顺流为有控制的回流;(4)隧道通风斜井的倾角不要受矿山常用的斜井倾角的限制,应视隧道的具体工程条件灵活取用。     

综合测井技术在太行山隧道勘察中的应用

研究目的:根据石太客运专线27.87 km长的太行山隧道洞身岩性以石灰岩、白云岩为主夹薄层角砾状泥灰岩、石膏岩及其次生的膏溶角砾岩,通过地区全部处于地下水的补给区,隧道区内断裂构造较发育,地下水较丰富的情况,在地质勘察阶段查明洞身岩层风化破碎程度、含水层及补给关系。研究方法:布置23个地质钻探孔,选择声波波速、视电阻率、自然电位、井温、井斜五个测试参数,同时以井中全景式彩色电视检测为补充,开展综合测井工作,采用概率统计方法对测试参数进行统计分析。研究结果:不同的岩性具有不同的概率曲线特征,灰岩、断层角砾岩、膏溶角砾岩离散度大,岩石破碎可能性大,对施工影响大。而鲕状灰岩、花岗片麻岩离散度小,岩石发生破碎的几率小。井中电视观测是对地下水出水情况进行判断最直接的方式。研究结论:采用上述方法可以准确判断岩层风化破碎程度、含水层及补给关系。     

Real-world gaseous and particle emissions of a Bi-fuel gasoline/CNG Euro 6 passenger car

The objective of the present study is the assessment of the environmental impact of a bivalent (bi-fuel) vehicle, running either on gasoline or compressed natural gas (CNG). To that aim, a Euro 6 passenger car was tested under various real-world driving conditions. In order to cover the full range of conventional powertrains currently in the market, the tests were also repeated on a Euro 6 diesel passenger car. Both cars were driven in two routes, the first complying with the regulation limits and the second going beyond them. Carbon monoxide (CO), nitrogen oxides (NO_x) and particle number (PN) emissions were recorded using a Portable Emissions Measurement System (PEMS). Apart from the aggregated emission levels, in g/km, the exact emission location along the route was also assessed. Natural gas proved beneficial for CO and PN emissions, the level of which always remained below the respective legislation limits. On the other hand, under the dynamic driving conditions with gasoline, the relevant limits were exceeded. Cold start, occurring at the beginning of the urban part, and motorway driving were identified as major contributors to total emissions, especially in gasoline mode. However, the application of natural gas was associated with a penalty in NO_x emissions, which were significantly increased as compared to gasoline. Local peaks within the urban part were identified in CNG mode. In any case, the diesel vehicle was by far the highest NO_x emitter.     

桥墩模态分析的一种新方法

以既有实测资料的桥墩为原型,用三维块体单元模拟墩身,用GOODMAN无厚度单元模拟桥墩与地基土的相互作用,建立了考虑三维耦合有限元单墩模型。并利用现场测试资料,对模型进行了验证和参数优化。然后分析不同基底约束、不同单元形式和不同墩身截面形状对桥墩自振特性的影响。对几座典型桥墩进行了自振特性的仿真分析。经与实测值对比,建立的三维实体单墩模型能够比较准确地计算各种桥墩的自振频率。计算表明,圆端型桥墩与截面积相等的等效矩形桥墩的自振特性非常接近,因此,仿真计算中可用矩形桥墩代替圆端形桥墩,可以节省计算资源,简化建模工作量,而且误差较小。