沥青路面技术改造结构的探讨

旧路补强设计理念采用的是长寿命路面设计原则,针对3种不同的破坏形式,提出不同结构的补强措施,根据旧路不同的使用状况选择不同的结构类型,采取分段设计、分类处理、分期实施、合理决策的原则进行,而且大量采用了旧路废料,这不仅降低了道路的改造费用,提高了资源再生利用率,而且还保护了环境,具有良好的经济效益和社会效益。     

Micro-electro-mechanical-sensor inertial navigation system-assisted global navigation satellite system receiver acquisition scheme and performance evaluation

When an aircraft moves under a low carrier-to-noise ratio (CNR) or at a high speed, increasing the sensitivity of global navigation satellite system (GNSS) receiver is a goal quite hard to achieve. A novel acquisition scheme assisted with micro-electro-mechanical-sensor (MEMS) inertial navigation system (INS) is presented to estimate the Doppler caused by user dynamics relative to each satellite ahead of time. Based on tightly coupled GNSS/INS estimation algorithm, MEMS INS Doppler error that can be achieved is first described. Then, by analyzing the mean acquisition time and signal detection probability, the MEMS INS-assisted acquisition capabilities in cold, warm and hot starts are quantitatively determined and compared with the standard GNSS acquisition capability. The simulations and comparisons have shown that: the acquisition time in cold start can be shortened by at least 23 s, the time in warm start can be shortened to 1 s and the acquisition capability is improved 95%, and the reacquisition time in hot start can be shortened by around 0.090 s and the capability can be enhanced 40%. The results demonstrate the validity of the novel method.     

基于GIS的道路热区鉴别方法

基于地理信息系统以及热区基本模型,研究了道路热区的鉴别方法。该方法对道路网依据一定优先权进行合并以获取道路基本单元,模拟了交通事故的空间分布,并采用Monte Carlo法定义各道路基本单元交通事故数阈值,通过检验道路基本单元的空间邻近性得到热区,并对上海世博园周边道路热区进行了鉴别。分析结果表明:道路网经合并后,不规则道路基本单元的百分比由41.5%下降到14.8%;世博园周边共有84个仅涉及车辆、33个涉及行人的热区,与实际相符。可见,该方法能有效鉴别道路危险区域。     

Analysis of peak and non‐peak traffic forecasts using combined models

Accurate and timely traffic forecasting is crucial to effective management of intelligent transportation systems (ITS). To predict travel time index (TTI) data, we select six baseline individual predictors as basic combination components. Applying the one‐step‐ahead out‐of‐sample forecasts, the paper proposes several linear combined forecasting techniques. States of traffic situations are classified into peak and non‐peak periods. Based on detailed data analyses, some practical guidance and comments are given in what situation a combined model is better than an individual model or other types of combined models. Indicating which model is more appropriate in each state, persuasive comparisons demonstrate that the combined procedures can significantly reduce forecast error rates. It reveals that the approaches are practically promising in the field. To the best of our knowledge, it is the first time to systematically investigate these approaches in peak and non‐peak traffic forecasts. The studies can provide a reference for optimal forecasting model selection in each period. Copyright © 2010 John Wiley & Sons, Ltd.     

基于出行规律的高峰小时客流OD矩阵快速估算方法

为了快速准确地计算城市交通高峰小时客流OD矩阵,提出一种简单易行的推算方法。该方法近似认为城市出行均为由家出行,从而将交通产生-吸引矩阵分解为一个由家出发的OD矩阵和一个返回家里的OD矩阵,通过调查交通高峰小时系数,将由家出发的OD矩阵与返回家里的OD矩阵按一定比例进行叠加即得到高峰小时客流OD矩阵,并应用该方法进行了算例分析。结果表明:该方法简单易行,抓住了出行的主要规律,可省去大规模的调查,具有一定的科学性与准确性,在潍坊市滨海交通客流规模预测研究中得到了较好的应用。     

贵州山区高速公路滑坡类型及特征分析

贵州山区高速公路建设中出现的滑坡主要有破碎岩体滑坡、堆积体滑坡、基岩顺层滑坡、填方路基滑坡等。介绍了不同地质条件下工程建设产生的滑坡类型、规模及影响,分析了滑坡的诱发因素,阐述了勘察设计过程中的重点和难点,以及采取的处治措施等。     

沥青路面就地热再生技术应用现状分析

沥青路面就地热再生技术是一种新的路面养护技术。文章从就地热再生技术的原理出发,分析了就地热再生技术的特点和适用条件,以及判断是否适合就地热再生应注意的问题,比较了就地热再生与传统工艺的优势和差别,介绍了就地热再生技术在国内外的应用现状。     

高速公路路面养护若干问题的思考

通过沈海高速公路路面使用寿命周期内的养管实例,就路面结构测试、维修养护和大修改建等问题提出一些看法。     

汽车热式空气流量计测量电路分析与实车检测

为详细说明热式空气流量计的具体工作原理,重点分析了热式空气流量计的实际测量电路,并对温度补偿进行了适当说明,介绍了CORALLA轿车的空气流量计,利用BOSCH—FSA740发动机性能分析仪对其进行检测,得出了不同转速下的信号电压。     

一种探测砂土中软黏土包的瑞雷波方法

填海造陆地基固结过程中容易形成软黏土包,给现场监测数据的分析和解释造成困难,因此有必要对砂土中的软黏土包进行定位。提出探测填海造陆地基砂土中软黏土包的瑞雷波方法。采用两道瑞雷波法提高瑞雷波检测的横向分辨率,同时在测试场地进行静力触探法检测,通过对比验证了瑞雷波法在软黏土包定位中的有效性。通过连续数次进行多道信号提取,绘制了较大范围内软基土体的两道瑞雷波相速度剖面热图,由热图可以直观地发现软黏土包及其基本性质。