为了研究城市不同交通方式通勤者颗粒物暴露水平、颗粒物浓度影响因素以及不同粒径粒子数量浓度分布,利用便携式Grimm11—A粉尘监测仪在2019年1月对高峰期和非高峰期4个时段的交通微环境颗粒物浓度及粒子粒径分布数据进行64次采样.结果表明,自行车通勤者细颗粒物(PM)暴露剂量最大(PM10、PM2.5和PM1.0分别为2285.6、1312.7、1035.5 min·μg/m3),其余依次是出租车、公交车,地铁暴露剂量最小;四种通勤方式中,PM10和PM2.5暴露浓度与空气质量监测数据之间具有强正相关性,其中,数量浓度与相对湿度的相关系数均大于0.82;粒子数浓度主要分布在0.25～0.7μm(>99％),粒径小于2.5μm粒子数累计贡献率达99.9％.研究结果有助于通勤者选择低暴露通勤路线.

The application and durability of the arch bridge rely on the hinge core of the two-hinged arch bridge.In this essay,considering the engineering project replacing the traditionally-designed lead-hinge core by reinforced concrete hinge core,the author give us an overall analysis of the construction process and principle.After following-up and investigation over one year,application of reinforced con-crete hinge core leads to effective result eventually.

During the construction process of cantilever casting box girder,the unbalanced moment is easily caused to result in tensile stress and affect the safety of construction.However,this problem can be handled by using inner equilibrium system.Combined with engineering practice,this paper analyzes the force of inner equilibrium system which is applied in cantilever casting box girder construction and calculates the bearing capacity.The result shows that inner equilibrium system can solve the problem of tensile stress in traditional cantilever casting box girder construction and enhance the safety of construction effectively.

The winter is the season of the project quality accident because the winter construction is affected by unfavorable factors,such as construction conditions and the environment,etc.The more of quality accident are concrete projects.We should research winter construction technology and assurance measures because the quality accident has hidden.

During the construction of bearing platform under water,foundation pit is usually unstable because of the intrusion of water.Therefore,how to avoid the impact of water on foundation pit is always a difficulty in bridge engineering.Combining with the engineering practice,the paper expatiates on the construction method and application effect of light well-point dewatering in construction of bearing platform under water.The result shows that the application of light well-point dewatering in construction of bridge bearing platform under water can reduce cost and shorten construction period.

In connection with the problem of inconvenient adjustment of commercial vehicle double steering front axes caging device,overall steering mathematical model and three-dimensional model are built,specific parameter values after conversion is calculated and best simplified adjustment method is proposed.Experiment shows that the adjustment method is correct.

Faced with energy crisis and environment pollution,the sustainable green transportation emerges as the times require. The green transportation is fit with the small cities in Northwest China. Based on resident′s trip rules,some measures are put forward from the viewpoints of land use,tra-nsportation management,transportation technology and so on,which can provide reference for green transportation development.

It discusses the influence aroused by strength state of the pavement structure to the interlayer touch condition. Calculation and analysis shows: the interlayer touch condition can greatly affect the strength state of the road pavement, and touch condition of different interlayer has different influence degree to the strength of the pavement structure.The touch condition of the first and second interlayer have greater influence to the tension stress of the bottom layer.The first interlayer has fatefully influence to the shear stress, while the touch condition of the third interlayer affects the compression strain of the top of ground.

Based on experiment of per actual project of maintaining a certain highway with micro-surfacing construction technology in the northern areas of China,this paper analyses the factors such as material testing,mixture quality,construction quality and final quality inspection.The research proves that micro-surfacing construction technology is of superiority in road-maintaining.

我国汽车年产量与保有量的快速增加对大气环境造成了很大的影响.针对降低汽车尾气排放;保证人民的健康;实现经济、环境以及人民生活水平的可持续发展等现实性问题,探讨了当前普遍使用汽油和柴油车的情况下,主要从法规、汽车发动机自身技术的改进以及机外处理技术等三个方面论述减少汽车尾气排放的措施.最后讨论了当前汽油和柴油车尾气处理技术.

以VOLVO B230F型电控汽油喷射发动机为对象,分析研究了节气门位置传感器的全负荷信号对发动机性能的影响,针对节气门位置传感器故障造成的发动机性能变化的对比分析表明:节气门位置传感器的全负荷信号丢失以后,混合气变稀,功率下降;CO和HC排放降低,NOx排放升高.最后指出了节气门位置传感器在电控发动机故障诊断中的作用.