基于远程监测的车辙等效温度预估模型建立

针对沥青路面车辙等效温度预估模型建立过程中,路面温度预估模型无法快速准确地测定不同时刻各深度结构层的实时温度数据和计算过程复杂等问题,通过埋设温度传感器,连接实时温度监测系统,采集不同时刻各深度结构层的实时温度。同时通过自行开发的计算程序,建立车辙等效温度预估模型。研究结果表明,远程监测系统可即时建立车辙等效温度预估模型,为公路养护的及时性和制定长周期养护规划提供可靠基础。     

Grid convergence study in the resistance calculation of a trimaran

As a new type of hull form, trimaran has remarkable excellent performances and has drawn more and more attention. When the viscous CFD technology now available is applied to the research of resistance performance of trimaran, the spatial discretization would usually result in the grid error and uncertainty, and thus the considerable discrepancy between the numerical results and the experimental data. In order to ascertain how much the grid would affect the calculation, the grid convergence should be studied. A mathematical trimaran was chosen as an example, with the commercial code CFX for the simulation, VOF for surface treatment, and the grid study was carried out based on two different turbulence models. It was concluded that carrying out grid study is helpful in estimating the grid error and uncertainty, and indicating the direction of improving the credibility of the numerical calculation, and, in addition to grid errors and uncertainties, the turbulence modeling errors and uncertainties contribute to the simulation errors.     

既有线铁路路基密实状态检测方法研究

针对现行既有线铁路路基检测中存在的技术缺陷,提出既有线路基检测新方法—可变能量贯入测试法,通过检测贯入阻力评价既有路基密实状态,达到不干扰行车、检测深度大、数据准确直观的目的。同时通过理论分析及现场对比试验研究,论证了采用可变能量贯入测试法检测贯入阻力评价铁路路基密实状态的可行性,并提出适于既有路基密实状态检测的建议标准。该成果的研究对优化我国既有线检测方法,保障行车安全具有积极意义。     

Determining the hydrodynamic forces on a planing hull in steady motion

A combination of methods was developed that can determine hydrodynamic forces on a planing hull in steady motion. Firstly, a potential-based boundary-element method was used to calculate the hydrodynamic pressure, induced resistance and lift. Then the frictional resistance component was determined by the viscous boundary layer theory. Finally, a particular empirical technique was applied, to determine the region of upwash geometry and determine spray resistance. Case studies involving four models of Series 62 planing craft were run. These showed that the suggested method is efficient and capable, with results that are in good agreement with experimental measurements over a wide range of volumetric Froude numbers.     

建立船舶预告登记制度的探讨

SUN预告登记制度起源于早期普鲁士法所规定的异议登记,后来为德国、瑞士、日本等国以及中国台湾地区民法所接受,成为民法中一项重要的物权制度。它将物权法理论和债权法理论结合起来,对保障当事人的权利、保护交易安全、维护市场信用具有重要作用。十届全国人大五次会议通过的《中华人民共和国物权法》对预告登记制度作了相关规定。文中结合物权法中预告登记制度的基本原理,针对目前船舶登记工作中尚未制定该制度的欠缺,对船舶登记工作中建立预告登记制度进行了初步的探讨。     

Stated preference analysis of travel choices: the state of practice

Stated preference (SP) methods are widely used in travel behaviour research and practice to identify behavioural responses to choice situations which are not revealed in the market, and where the attribute levels offered by existing choices are modified to such an extent that the reliability of revealed preference models as predictors of response is brought into question. This paper reviews recent developments in the application of SP models which add to their growing relevance in demand modelling and prediction. The main themes addressed include a comparative assessment of choice models and preference models, the importance of scaling when pooling different types of data, especially the appeal of SP data as an enriching strategy in the context of revealed preference models, hierarchical designs when the number of attributes make single experiments too complex for the respondent, and ways of accommodating dynamics (i.e. serial correlation and state dependence) in SP modelling.An earlier modified version was presented as the keynote address to the 1993 National Conference on Tourism Research, held at the University of Sydney, 19 March 1993. The comments of Jordan Louviere, Lester Johnson, Paul Hooper, W.G. Waters II and Mark Bradley are appreciated.     

高速公路交通事故数据分析方法研究

高速公路交通事故数据对管理部门提升道路交通安全具有重要意义。为研究贵州省某两条高速公路历史交通事故数据分布规律与事故发展趋势,首先利用邻近度与关联性分析方法,完善事故数据;然后分析道路特征对交通安全的影响,划分连续下坡路段、隧道路段单元范围;最后对路段单元进一步划分为区块,建立不同区块范围内的事故概率与区块位置的预测模型,其中连续下坡路段后半段符合线形关系,隧道进出口段符合二次函数关系,并根据事故分布特征提出改善方案,进而辅助管理者掌握不同特征路段未来可能发生交通事故的路段范围以及改善的优先级。     

不同错台量对复合型密封垫影响及长期防水预测

为研究盾构隧道管片接缝不同错台量对复合型密封垫防水性能的影响,从复合型密封垫遇水膨胀橡胶块二次防水效应出发,在不同错台量条件下分别从密封垫-密封垫接触面和密封垫-密封槽接触面2 个方面分析复合型密封垫防水渐进失效机制,同时基于阿累尼乌斯方程的“P-T-t”三元模型对复合型密封垫长期防水性能进行预测。研究结果表明: 1) 复合型密封垫遇水膨胀橡胶块发生膨胀作用,能够有效增加密封垫间接触面应力,并且密封垫渗漏处主要出现在密封垫与密封垫接触面上; 2) 对于密封垫与密封槽接触面防水能力,随着接缝错台量的增大,对遇水膨胀橡胶块膨胀作用的影响显著; 3) 管片接缝间的张开量和错台量对复合型密封垫的长期防水性能影响显著,并且复合型密封垫长期防水性能随着老化时间先急剧下降后达到平稳状态。     

地下结构抗震动力可靠度分析

由于地震的随机性,开展地下结构随机地震响应及其抗震可靠度分析具有重要的实际意义。本文从有限元动力分析的基本原理出发,利用脉冲响应函数和傅立叶变换原理,研究了将地震荷载作为平稳随机过程时地下结构随机地震响应分析方法,导出了平稳随机地震作用下地下结构动力响应的数字特征计算表达式。分析了地下结构在某烈度地震作用下和设计基准期内的抗震可靠度。     

乳化沥青冷再生混合的室内设计与性能评价研究

针对乳化沥青冷再生混合料初期易松散破坏的特点,文中提出了新的设计和性能评价方法。设计方法采用Su-perpave体积设计法,并给出合适的室内成型工艺;混合料性能的评价分两阶段:成型初期,采用修正肯塔堡飞散试验和冻融劈裂试验分别评价混合料的初期抗松散性和其中存在的水对路用性能的影响;成型后期,采用车辙、冻融劈裂、小梁弯曲来控制混合料的长期路用性能。最后,采用该方法对实际工程材料进行了验证,取得了较好的效果。