基于类间距优化的分心驾驶行为识别模型训练方法

分心驾驶行为识别任务可以看作细粒度图像分类任务,即图像中较小区域所包含的特征决定了该图像的类别,如一张图像是正常驾驶还是与副驾驶聊天完全由驾驶员的脸部朝向来决定.对于那些图像差异很小的类别,图像分类通常训练方法训练出的模型无法高精度地区分.针对这一问题,提出了基于类间距优化的分心驾驶行为识别模型训练方法,通过增大模型从...     

Evaluation of an existing bus network using a transit network optimisation model: a case study of the Hiroshima City Bus network

This study evaluates an existing bus network from the perspectives of passengers, operators, and overall system efficiency using the output of a previously developed transportation network optimisation model. This model is formulated as a bi-level optimisation problem with a transit assignment model as the lower problem. The upper problem is also formulated as bi-level optimisation problem to minimise costs for both passengers and operators, making it possible to evaluate the effects of reducing operator cost against passenger cost. A case study based on demand data for Hiroshima City confirms that the current bus network is close to the Pareto front, if the total costs to both passengers and operators are adopted as objective functions. However, the sensitivity analysis with regard to the OD pattern fluctuation indicates that passenger and operator costs in the current network are not always close to the Pareto front. Finally, the results suggests that, regardless of OD pattern fluctuation, reducing operator costs will increase passenger cost and increase inequity in service levels among passengers.     

UHPC 养护温度对力学性能的影响

众所周知,热养护能够显著提升UHPC的早期强度,但目前工程应用中,较高的养护温度（≥80℃）通常实现较为困难,与日益增长的绿色环保需求相违背。为了推广UHPC应用与指导工程项目的施工,提出相对容易实现的低温（30~70℃）热养护,研究30℃、50℃、70℃、90℃条件下先分别热水养护1 d、2 d、3 d和4 d的力学性能发展情况,同时与标养28 d之后的力学性能进行对比。结果表明,在30℃、50℃和70℃条件下养护4 d后,抗压强度分别是90℃热水养护2 d的69.4%、88.6%和92.9%,是标养28 d的83.8%、107.0%和112.2%。抗弯拉强度随温度和养护时间增长的变化幅度相对较小,几种养护温度4d的抗弯拉强度偏差在4%以内。可见相对低温的热养护能够满足对UHPC力学性能的要求。     

基于模糊评价方法的改进综合调整法确定二手车价值

针对我国二手车市场中长期存在的价值评估难题,利用重置成本法的原理,将影响二手车价格的各种因素作为综合调整系数,并采集多位专家意见,形成系数的权重矩阵,再通过采用最小二乘算法的模糊评价方法计算得到最优的各调整系数权重分配结果,从而作为改进的综合调整法计算确定二手车价值.与传统方法相比,文中采用的方法能在保留专家的主观经验,体现实际市场情况的同时将主观偏差最小化.     

Investigation of springback behavior and process control for stamping of ring-shaped workpiece

Due to the elastic deformation of metal stamping, springback is a serious problem to cause shape deviation and thus reduce precision. The springback behavior of ring-shaped workpiece is investigated in this paper and an auxiliary boss device is proposed to control the springback deformation. A finite element model is developed.The characteristic parameters including boss height, boss angle and boss gap are discussed systematically. It can be concluded that the gap has a positive linear correlation with springback percentage, and the boss angle has an optimal interval of 30°—60° to reduce springback. When the boss height increases, the springback decreases,but the effect weakens when the boss height is larger than 1.0 mm. Then, a response surface analysis is conducted with Design Expert 8.0.5 software and an optimal parameter process window(i.e., boss height from 2.1 to 3.0 mm,boss angle from 53° to 60° and the gap from 0 to 1.2 mm) is obtained. Finally, a set of molds are fabricated and the stamping experiments are conducted. The springback behavior is well controlled. The springback percentage can be decreased from 33% to 6% by using the auxiliary boss device of ring-shaped workpiece.     

后疫情时代交通运输领域的一体化碳减排政策

交通运输领域的碳减排目标可以基于碳排放恒等式和DIRECT方法论的无缝政策制定和实施过程管理来实现.首先,基于交通运输领域的碳排放恒等式,提出碳减排目标可以从六个环节实现:1)减少交通运输能源消费的碳排放强度;2)降低交通运输活动的能源消费;3)减少生活和经济活动对交通运输的压力;4)减少为满足需求的高碳生活和经济活动量;5)改变高碳生活和经济需求;6)人口政策.DIRECT方法论包括六个步骤:1)探知、检测;2)告知、介入;3)反应;4)启蒙、强化、评估;5)协作;6)传承.这六步是实现以上每个环节必需的步骤.基于以上内容,提出制定和实施交通运输领域碳减排的无缝一体化政策的六环六步法.     

基于Icepak的水冷板结构优化设计

针对水冷板的热设计,在理论分析的基础上,确定影响水冷板散热的结构因素。通过在电子设备热分析软件Icepak中建立水冷板的热仿真模型,探讨水冷板结构形式对散热的影响,得到了肋片高度、长度、数量和宽度对水冷板散热效果的影响规律,实现了水冷板的结构优化,为后续水冷板的热设计奠定了基础。     

浅谈以NSM规则理念规范海事船舶管理的可行性

本文结合福州海事局所属海事船舶在管理中以NSM规则为指导,建立并运行海巡艇安全管理体系的做法,提出运用NSM规则理念规范海巡艇管理的新思路,旨在进一步提高海事船舶"管用养修"的水平,真正做到海事船舶管理的"规范化、制度化、标准化"。     

沅江特大桥桥上无缝线路设计分析

针对怀邵衡铁路沅江特大桥桥跨结构和桥上轨道结构特点,分析了钢桁拱上设置钢轨伸缩调节器的设计方案和相应的无缝线路计算结果。计算结果表明,由于在钢轨伸缩调节器两端存在伸缩区,伸缩区范围内的梁跨将承受更大的无缝线路附加力。因此从行车的平顺性、舒适性及线路少维修的角度考虑,轨道结构设计应尽量避免设置钢轨伸缩调节器。     

胶接、胶焊与点焊接头箱型梁耐撞性强度试验分析

通过对车用结构胶胶接接头、胶焊接头和点焊接头箱型梁的碰撞实验,得到了碰撞小车的加速度时间曲线;把碰撞小车加速度平均值作为箱型梁结构强度的评价指标,加速度平均值越大,梁结构越强.通过上述指标分析了各种连接接头梁强度大小差异的原因.研究表明:3种连接方式的实验加速度时间曲线都有很好的规律性,在各种焊点间距下,胶焊接头的箱型...