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.     

车辆隔热壁K值计算中空气层的处理方法

对轨道交通车辆多层复合结构的隔热壁进行隔热性能理论计算与仿真计算的对比,对隔热壁内部空气层的隔热性能进行分析。结论为:在车辆多层复合结构的隔热壁K值计算中,当空气层厚度大于一定厚度时,流体自然对流对隔热壁的隔热性能影响较大。利用多项式密度(Polynomial Denisity)和Boussinesq模型两种算法,对所得结论进行了验证。     

行政裁决:地方政府的制度推力

在统计时间内有效的行政裁决制度共有16项,分布在自然资源和环境、知识产权以及民间纠纷三大领域,均为中央政府的法律、行政法规和部门规章所设定.但行政裁决设定的领域范围在逐步退缩,已设定的行政裁决被纷纷废止,新的法律更倾向规定调解或仲裁.行政裁决实施性规定多集中于与土地有关的行政裁决,其中绝大多数系由地方政府所制定.地方政府不仅做出了细密规定,而且纷纷制定了专门性规定.但在矿权、环境、知识产权和民间纠纷领域,地方政府并未充分发挥出细化法律、行政法规和部门规章中行政裁决条款的作用,更没有制定专门的行政裁决规定.有关行政裁决的行政规范性文件高度集中于征地补偿裁决、拆迁补偿裁决和林地权属裁决.其中,林地权属裁决的中央行政规范性文件较多,征地补偿裁决和拆迁补偿裁决的地方行政规范性文件较多.这些行政规范性文件的内容,集中在纠纷的化解而非行政裁决制度本身.从行政裁决引发的诉讼案件反观行政裁决制度,征地补偿裁决、拆迁补偿裁决和林地权属裁决都在运行,其他行政裁决制度都没有运行.其中,拆迁补偿裁决的运行异常活跃,征地补偿裁决的运行却极为低迷.统计发现的耦合是:凡地方政府对行政裁决制定了专门性实施规定的,行政裁决制度都在运行,否则都已停滞；地方行政规范性文件被用作行政裁决依据的多少,与该行政裁决的活跃程度成正比.当然,上述发现的证成或证伪,有待于另一项研究.     

艰险山区铁路施工营地建设关键技术问题研究

艰险山区铁路工程沿线地区一般具有自然灾害频发、高原高寒缺氧、建设条件极为困难、施工周期超长等复杂的外部环境。为满足艰险山区铁路施工营地建设“以人文本”需求,给参建人员生活提供适宜安全的环境,基于艰险山区铁路工程施工营地建设的外部环境分析,从房屋材质备选方案比选、营地建设需解决的关键技术问题、节能环保等方面对施工营地建设关键技术问题进行研究,并提出具体的方案与建议。研究成果可为山区铁路及类似工程的施工营地建设提供参考借鉴。     

基于SUMO的大型活动三层级公交疏散保障方案仿真

大型活动客流具有短时集聚与疏散的特点,为保障活动结束后场馆附近公交客流的快速有序疏散,构建三层级公交疏散运保体系,包括公交常规线、专用快线和微循环线.按客流量疏散目的地将其分为城市市内的内散客流量和需前往高铁站、飞机场等对外客运枢纽换乘至其他城市的外散客流量.对内散客流量,采用微循环线将乘客运送到公交常规线站点接驳出行;对外散客流量,采用微循环线将乘客运送到专用快线站点,再运送到对外客运枢纽.基于SUMO仿真平台,选择苏州市奥林匹克体育中心体育馆作为大型活动承办场所,仿真三层级公交保障方案下的客流疏散场景,更直观地说明微循环线的作用及其与公交常规线和专用快线的联动特点.     

集美大学教学实习船“育德”轮总体设计

"育德"轮是上海船舶研究设计院为集美大学设计的用于航海专业教学实习、科学研究兼顾货物运输的教学实习船。该船是目前世界吨位最大的教学实习船,配备了功能齐全的教学设施、先进的科研设备以及舒适的学习生活环境。该船还具有安全性高、绿色环保和经济性优异等特点。     

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。     

船舶小组立装焊作业单元CPS系统研究与应用

当前船厂小组立装焊作业过程存在作业任务信息无法直接传递至现场,现场实际执行的状态信息无法及时反馈等问题,导致装焊作业混乱、装焊效率低下.为了解决上述问题,针对船舶小组立装焊作业单元进行研究,构建基于信息物理融合(CPS)的智能制造系统.首先分析了小组立装焊作业流程;然后梳理了装焊作业任务数据,构建了小组立装焊作业数据模型,并在此基础上,完成了基于物联网的CPS框架设计以及系统功能开发,实现了对装焊作业过程的有效监控;最后将该系统应用于某船厂小组立装焊现场,有效规范了装焊作业过程,提高了装焊效率.     

Characteristics analysis for travel behavior of transportation hub passengers using mobile phone data

The travel behavior of passengers from the transportation hub within the city area is critical for travel demand analysis, security monitoring, and supporting traffic facilities designing. However, the traditional methods used to study the travel behavior of the passengers inside the city are time and labor consuming. The records of the cellular communication provide a potential huge data source for this study to follow the movement of passengers. This study focuses on the passengers’ travel behavior of the Hongqiao transportation hub in Shanghai, China, utilizing the mobile phone data. First, a systematic and novel method is presented to extract the trip information from the mobile phone data. Several key travel characteristics of passengers, including passengers traveling inside the city and between cities, are analyzed and compared. The results show that the proposed method is effective to obtain the travel trajectories of mobile phone users. Besides, the travel behavior of incity passengers and external passengers are quite different. Then, the correlation analysis of the passengers’ travel trajectories is provided to research the availability of the comprehensive area. Moreover, the results of the correlation analysis further indicate that the comprehensive area of the Hongqiao hub plays a relatively important role in passengers’ daily travel.

     

Hybrid process of fabricating high-quality micro wine-glass fused silica resonators

A new hybrid method, which combines improved glass-blown technology with wet etching, is reported to fabricate micro wine-glass resonators with high-quality fused silica. The optimum placement is compared to achieve the resonators with good shell shape. The typical shell diameter is about 4mm and its thickness covers from dozens to hundreds of micrometers. The etching rates in corrosion solutions with different ratios and at different thicknesses of hemispherical shells are studied. We also conclude how to precisely control the thickness. The corrosion solutions with different ratios of HF solution to NH₄F solution make the spherical shells rougher in different degrees. The best roughness is 0.581 nm in the 1: 8 ratio corrosion solution while the original roughness is 0.537 nm. This fact shows that the resonator remains atomically smooth surface. Based on the glassblowing spherical fused silica structure, the thickness of the resonator is effectively controlled by buffered oxide etch (BOE) technology according to the measured etching rate. The measured resonant frequency of the hemispherical shell at ambient pressure and room temperature is 1.75 kHz of rocking mode which is close to the simulated frequency. Using such a low-cost hybrid approach, we can fabricate high-quality microscale resonators in batch.