石灰土中石灰活性衰减规律研究

通过试验的方法研究松散石灰土在常温和低温开放状态、常温密封状态条件下石灰活性衰减的规律，推定出不同状态条件下石灰活性衰减率公式，以确定石灰土合理的闷料时间，减少不必要的石灰活性衰减和未消解石灰对路面基层的破坏，为石灰土路面基层质量问题的界定提供依据。     

V形刚构桥施工中倒三角区域支架的拆除时机分析

采用桥梁博士软件模拟一座典型的V形墩连续刚构桥的施工过程,为找出支架拆除对传力途径的影响,分别单独计算结构自重、预应力以及收缩徐变内力,然后对单因素分析的结果进行组合。分析结果表明倒三角区域支架的拆除时机对桥梁在施工阶段及成桥后的内力均有显著影响,可达50%以上。建议优先采用早拆支架方案,以使结构受力明确,且对V形墩区域受力有利。     

特种弹药铁路运输可调式定位装置研究

概述了特种弹药铁路运输可调试定位装置的主要功能、技术要求、主要战技术指标，介绍了特种弹药铁路运输采用的从箱体顶部固定方式，并进行了相应的可调式定位装置研究，将装置分为整体固定和单点独立固定两种，用于固定弹箱在敞车内的位置，确保弹体运输安全。     

关于沥青混凝土路面的常见病害及防治措施

沥青混凝土路面主要应用于公路的面层,由于沥青混凝土材料本身的差异,以及受设计、施工水平的影响,沥青路面常常出现松散、脱皮、冻胀翻浆、水破坏、沉陷、开裂、泛油、坑槽等病害。这些病害的出现严重影响了路面行车速度、行车安全、加大了汽车磨损、缩短了沥青路面的使用寿命,使行车不畅,行成交通压力,造成道路使用年限缩短。本文具体结合工程项目阐述沥青混凝土的施工工艺、病害分析及防治措施。     

Effect of interference fits on the fatigue lives of bolted composite joints

The effect of interference fits on the fatigue lives of bolted composite joints is investigated by conducting mechanical tests. Static and fatigue tests are carried out on specimens made of carbon-bismaleimide composites joined together as double-lap single-bolt joints. The bolts having interference fits ranging of 0 (neat fit), 0.5%, 0.75% and 1% are performed. The results demonstrate the relationship between fatigue life and different values of interference fits. After the fatigue tests, non-destructive evaluation (NDE) and scanning electron microscope (SEM) are used to observe the damage of the surrender and surface of the hole. The test results show that the interference fitted specimens have improved fatigue life compared to the neat fitted specimen. The NDE and SEM results reveal that the damage degree of interference fitted specimen is weaker than that for the neat fitted one.     

Two degree of freedom flow-induced vibration of cylindrical structures in marine environments: frequency ratio effects

The flow-induced vibration of a cylindrical structure is a very common problem in marine environments such as undersea pipelines, offshore risers, and cables. In this study, the vortex-induced vibration (VIV) of an elastically mounted cylinder at a low Reynolds number is simulated by a transient coupled fluid–structure interaction numerical model. Considering VIV with low damping ratio, the response, hydrodynamic forces, and vortex shedding modes of the cylinder is systematically analyzed and summed up the universal rule under different frequency ratios. On the basis of the analysis, we find that the frequency ratio α is a very important parameter. It decides the locked-in, beat, and phase-switch phenomena of the cylinder, meanwhile, it also influence the vortex mode of the cylinder. The trajectory of the two degrees of freedom (2 DOF) case at different natural frequency ratios is discussed, with most trajectories having a “figure of 8” shape and a few having a “crescent” shape. A fast Fourier transformation technique is used to obtain the frequency characteristics of the vibration of the cylindrical structure. Using the 2 DOF cylinder model in place of the 1 DOF model presents several advantages in simulating the nonlinear characteristics of cylindrical structures, including the capacity to model the crosswise vibration generated by in-line vibration.     

Assessing the representativeness of a smartphone-based household travel survey in Dar es Salaam,Tanzania

The household travel survey (HTS) finds itself in the midst of rapid technological change. Traditional methods are increasingly being sidelined by digital devices and computational power—for tracking movements, automatically detecting modes and activities, facilitating data collection, etc.. Smartphones have recently emerged as the latest technological enhancement. FMS is a smartphone-based prompted-recall HTS platform, consisting of an app for sensor data collection, a backend for data processing and inference, and a user interface for verification of inferences (e.g., modes, activities, times, etc.). FMS, has been deployed in several cities of the global north, including Singapore. This paper assesses the first use of FMS in a city of the global south, Dar es Salaam. FMS in Dar was implemented over a 1-month period, among 581 adults chosen from 300 randomly selected households. Individuals were provided phones with data plans and the FMS app preloaded. Verification of the collected data occurred every 3 days, via a phone interview. The experiment reveals various social and technical challenges. Models of individual likelihood to participate suggest little bias. Several socioeconomic and demographic characteristics apparently do influence, however, the number of days fully verified per individual. Similar apparent biases emerge when predicting the likelihood of a given day being verified. Some risk of non-random, non-response is, thus, evident.     

城市道路沥青路面补强设计方案浅析

抚顺市城市道路建设近年来有了很大发展,但城市道路使用到一定年限后,如果使用性能降低,就要及时进行补强。以抚顺市城市道路沥青路面补强设计的现状为基础,探讨了合理的沥青路面补强设计方案。     

A new method for absolute datum transfer in seafloor control network measurement

To decrease the time consumption and the labor intensity in the absolute datum transfer of traditional seafloor control network measurement, a new method, namely sailing-circle positioning method, is put forward in this paper. First, the traditional intersection positioning model is improved by considering the equivalent sound velocity profile error as an unknown parameter in the adjustment model. Second, the effect of geometric dilution of precision (GDOP) on positioning accuracy is analyzed. By seeking for the minimum of GDOP, it is concluded that the absolute datum transfer can achieve the highest accuracy in the condition of sailing along a circle relative to other sailing paths. Moreover, the optimal radius of the circle for the accurate datum transfer is also given out. Besides, the correlation between the accuracy of datum transfer and the sound velocity error in this method is analyzed. Finally, the new method was tested and verified by the experiments in Songhua lake with the water depth of 60 m and in South China sea with the water depth of 2000 m, respectively. These experiment results show that the new method can improve the accuracy and efficiency of traditional datum transfer method significantly.     

对地铁运营物资高效管理的探讨

随着城市轨道交通的快速发展,轨道交通网络加剧成型,物资供应和保障面临巨大挑战,探讨新的物资管理模式势在必行。本文着重围绕供应链中的各个实施要点阐述,从价格比对体系、采购计划、供应商、库存管理和物资配送等方面进行了论述,对于从事轨道交通物资管理的相关人员有一定的参考和借鉴意义。