公路桥梁维修加固技术经济评价方法研究

在桥梁维修加固实施过程中,不可避免的涉及到其经济合理性问题,目前还未有较为成熟和系统的方法,对桥梁维修加固的经济合理性进行评价。本文结合桥梁维修加固涉及到的宏观和微观方面,提出了一种新的评价方法,用以判断桥梁维修加固的经济合理性。     

赤泥做道路基层材料的试验研究

在分析山东铝业赤泥理化性质的基础上,进行了赤泥做道路基层材料的配制和试验研究。试验研究表明:选用适当的配比,赤泥道路基层强度可满足高等级公路的要求,7d抗压强度可达到2 0MPa以上,28d强度3 0MPa以上,赤泥基层与传统的半刚性基层材料相比具有强度高、回弹值大等优点。这不仅可拓宽道路基层材料的应用范围,而且可使赤泥变废为宝。     

网络条件下高速公路收费费率优化方法研究

以区域公路网为研究对象,在分析高速公路收费费率与交通量之间关系的基础上,建立收费费率优化双层规划模型,兼顾经营者和使用者的利益,并考虑路网交通流分布,设计了模型的实用求解算法。该方法弥补了已有方法多以运输通道为研究对象的不足之处,可以在收费系数确定的情况下根据优化目标直接得到优化结果,具有较为广泛的适用性。     

江苏省交通事故时间分布分析

根据江苏省有关交通事故数据,利用统计方法对交通事故发生的时间特征进行分析。通过分析交通事故年时间分布规律的波峰曲线,得出江苏省交通事故发生数量开始振荡变化,逐年上升的势头有望于近期遏制。通过分析交通事故、月、周、小时时间分布曲线,得出交通事故高峰小时出现在交通量高峰小时之后的9~12h、14~16h,两者不重合。死亡高峰时段(危险时段)多发生在18~21h的3h内。研究结论对不同时间内如何采取不同的安全对策来降低江苏省交通事故具有指导作用。     

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。     

Experimental investigation of evaporation rate and exhaust emissions of diesel engine fuelled with cotton seed methyl ester and its blend with petro-diesel

An experimental study to measure the evaporation rates, engine performance and emission characteristics of cotton seed biodiesel (cotton seed oil methyl ester) and its blends in different volumetric proportions with diesel is presented. The thermo-physical properties of all the fuel blends have been measured and presented. Evaporation rates of neat cotton seed biodiesel, neat diesel and their bends have been measured under slow convective environment of air flowing with a constant temperature. Evaporation constants have been determined by using the droplet regression rate data. The neat fuels and fuel blends have been utilized in a test engine with different load conditions to evaluate the performance, combustion and emission characteristics of the fuels. The specific fuel consumption values of the two blends, viz. B25 and B75 are found to be same. At the highest load, B0 records the lowest CO volume followed by B100. From the observed evaporation, performance and emissions characteristics, it is suggested that a blend of B50 and B75 can be optimally used in standard diesel engine settings.     

桥梁模板施工技术应用性研究

桥梁模板是桥梁施工中的重要工具。通过搜集国内外桥梁模板资料,研究总结并提出解决模板工程在桥梁施工中存在各种问题的办法,将对提高工程质量、加快施工速度、提高劳动生产率、降低工程成本和实现桥梁工程的文明施工起到一定的推动作用。     

硅胶吸附管采集甲醇汽车尾气排放中甲醇的方法研究

文章主要研究了利用硅胶吸附管采集甲醇汽车尾气排放中甲醇的方法,对硅胶吸附管的规格、待测样品的浓度、采样参数等进行了详细的讨论及验证。研究表明,利用硅胶吸附管采集甲醇的过程中,很容易发生甲醇的穿透。随着硅胶颗粒装填数目的增加,甲醇的穿透率降低,实际吸附甲醇的效率增加。在采样流量相同时,待测样品浓度越高,甲醇的穿透率越高。在待测样品浓度相同时,采集流量越高,甲醇的穿透率越高。将硅胶吸附管串联,可以有效减少甲醇的穿透,提高吸附效率。     

Dynamic simulation of train–truck collision at level crossings

Trains crashing onto heavy road vehicles stuck across rail tracks are more likely occurrences at level crossings due to ongoing increase in the registration of heavy vehicles and these long heavy vehicles getting caught in traffic after partly crossing the boom gate; these incidents lead to significant financial losses and societal costs. This paper presents an investigation of the dynamic responses of trains under frontal collision on road trucks obliquely stuck on rail tracks at level crossings. This study builds a nonlinear three-dimensional multi-body dynamic model of a passenger train colliding with an obliquely stuck road truck on a ballasted track. The model is first benchmarked against several train dynamics packages and its predictions of the dynamic response and derailment potential are shown rational. A geometry-based derailment assessment criterion is applied to evaluate the derailment behaviour of the frontal obliquely impacted trains under different conditions. Sensitivities of several key influencing parameters, such as the train impact speed, the truck mass, the friction at truck tyres, the train–truck impact angle, the contact friction at the collision zone, the wheel/rail friction and the train suspension are reported.