小型直喷式柴油机燃用生物质能燃料的性能研究

文章主要研究了生物质能混合燃料在柴油机上的应用,通过在一台小型直喷式柴油机上进行不同组分柴油-生物柴油-乙醇混合燃料的燃烧、油耗和排放性能对比试验,分析了乙醇含量的改变对混合燃料的发动机燃烧压力、滞燃期、放热规律、比油耗和排放的影响．     

冷试技术在发动机装配线上的应用分析

冷试技术具有较多优势,为让该项技术可以在汽车行业获得更大的应用空间,文章重点分析了汽车发动机装配线上冷试技术中关键技术的具体运用。文章通过对机油压力、扭矩、进气真空度及排气压力、高速NVH检测与低速NVH、曲轴与凸轮轴正时以及传感器线速进行检测,对冷试技术在发动机装配线上的运用进行了分析。了解到发动机冷试技术可以全方位提高我国发动机质量,压缩发动机的质量检测成本,在汽车行业具有较好的应用前景。汽车发动机由于各项新技术的发展应用,其系统结构更加复杂,发动机中的外购件占成本比例随之增长,汽车制造企业必须对零部件系统加强检测。希望可以为相关从业人员具有一定的参考作用,并推进汽车行业更好的发展。     

规范开展公路工程监督执法工作

介绍了交通工程质量监督的方式及内容,阐述了督查程序及对发现问题的处理方法.     

船体建造师培养机制研究与应用

文章以船体阶段建造师为实例,首先阐述建造师的培养目标,再根据船企实际情况建立建造师的培养机制以及制定推进的具体措施,通过实际应用情况证实建造师培养的必要性,有利于促进船企建造师阶层和建造文化的形成,实现为船企发展培养实战型管理人才的目的.     

隧道铣挖法铣挖参数数值模拟研究

基于PRO/E建立艾卡特ER1500-1XL铣挖头模型导入LS-DYNA中,选择DRUCKER-PRAGER本构模型模拟岩土材料,刚体模拟铣挖头进行铣削岩土仿真。通过数值模拟方法改变隧道铣挖法中铣削参数(吃刀深度,截割厚度,铣挖方式),结合现场资料得到隧道铣挖规律。结果如下:(1)截齿荷载平均值差异不大时差异系数较大是截齿破坏的主要原因;(2)吃刀深度和垂直摆动速度与单位比能耗呈指数关系,加大吃刀深度比摆动速度对加大截割厚度更有效,截割阻力与截割厚度成线性关系;(3)铣挖尽量采用顺切,较为省力,延长截齿寿命。     

水泥生产作业场所呼吸粉尘管理浓度研究

依据我国现行粉尘最高容许浓度,采用回归法、总粉尘与呼吸粉尘比例系数法研究了作业场所呼吸粉尘管理浓度.结果显示,游离SiO_2≤10%的水泥与煤尘管理浓度分别为2mg/m_3、3.5mg/m_3,与国家颁布的MAC一致:石灰石、混合生料粉尘分别为 3.5mg/m_3与3.1mg/m(?)(?)(?)粘土与熟料粉尘为4mg/m_3.     

Identification of emission hotspots in roundabouts corridors

This study describes a methodology to quantify and characterize the vehicular emissions of functionally interdependent roundabouts at a corridor level. Corridor segments include those upstream of each roundabout, the circulating area, downstream of the roundabout as well as midblock sub-segments between adjacent roundabouts. The main purpose of the study is to identify the locations along the corridors where emissions tend to be consistently high. These locations are termed “Emission Hotspots”. The methodology is applied to four existing roundabout corridors in San Diego (California) and Avon (Colorado) in the United States, and in Mealhada and Chaves (Portugal). An extensive sample of second-by-second speed traces is available for these four corridors with roundabouts.The analysis shows that when roundabouts are fairly spaced and have similar geometric design features, no significant differences are observed between emissions of roundabouts located in the corridor. In such cases, the downstream sub-segments are the emission hotspots both in absolute terms (overall contribution on total emissions is higher than 34%) and per unit distance (22% higher than the average corridor value). When roundabouts are unequally spaced the highest emissions hotspots (more than 9% above the average corridor value) are found at the circulating area sub-segments. The results also demonstrate that the entry deflection angle has a slight impact on the spatial distribution of emissions especially in the case of closely spaced roundabouts.     

LT5型摊铺机压实度的设计

以ＬＴ５型摊铺机为例，探讨了为达到压实度设计指标而采用的振捣功率计算、熨平板比压设计以及压实度均匀性设计方法。     

Driving cycles that reproduce driving patterns,energy consumptions and tailpipe emissions

This study presents the Energy Based Micro-trip (EBMT) method, which is a new method to construct driving cycles that represent local driving patterns and reproduce the real energy consumption and tailpipe emissions from vehicles in a given region. It uses data of specific energy consumption, speed, and percentage of idling time as criteria of acceptable representativeness. To study the performance of the EBMT, we used a database of speed, fuel consumption, and tailpipe emissions (CO₂, CO, and NO_x), which was obtained monitoring at 1 Hz, the operation of 15 heavy-duty vehicles when they operated within different traffic conditions, during eight months. The speed vs. time data contained in this database defined the local driving pattern, which was described by 19 characteristic parameters (CPs). Using this database, we ran the EBMT and described the resulting driving cycle by 19 characteristics parameters (CPs*). The relative differences between CPs and CPs* quantified how close the obtained driving cycle represented the driving pattern. To observe tendencies of our results, we repeated the process 1000 times and reported the average relative difference (ARD) and the interquartile range (IQR) of those differences for each CP.. We repeated the process for the case of a traditional Micro-trip method and compared to previous results. The driving cycles constructed by the EBMT method showed the lowest values of ARDs and IQRs, meaning that it produces driving cycles with the highest representativeness of the driving patterns, and the best reproduction of energy consumption, and tailpipe emissions.     

钻孔平台(栈桥)钢管及桩基钢护筒底部固结方案

文章结合广西武宣黔江特大桥工程实例,对深水且无覆盖层的倾斜岩面条件下的钻孔平台(栈桥)和桥梁桩基钢护筒底部固结定位施工的工艺流程及技术要点进行了介绍,为类似桥梁桩基施工提供技术参考。