基于BIM标准体系的铁路协同设计体系研究

随着物联网、云计算、大数据等前沿技术的不断进步,铁路行业正在迎来新的发展机遇。数字孪生铁路是以智能建造、智能装备、智能运营为核心的智能高铁技术应用数字环境,也是铁路工程全生命周期应用的数据基础。传统的设计方式中各专业内和专业间数据相对离散、逻辑关联性不高、成果不易维护且信息存在大量冗余,无法满足铁路智能化应用的要求。以京张客运专线BIM项目为载体,研究能够集中管理各专业设计资源、定制各专业设计参数交互流程、构建专业间数据层面逻辑关联、具有统一数据框架的协同设计体系。该体系强化了各专业间的联系,提升了设计质量,为工程数字化建设提供了数据结构组织有序、易于维护、动态可感知的数字孪生工程,同时也为勘察设计企业拓展工程全生命周期业务提供了可靠的技术保障。     

Modal analysis of real-time,real world vehicular exhaust emissions under heterogeneous traffic conditions

This study presents the characteristics of real world, real time, on-road vehicular exhaust emission namely, carbon monoxide (CO), nitric oxide (NO), hydrocarbons (HC), and carbon dioxide (CO₂) emitted under heterogeneous traffic conditions. Field experiments were performed on major category of vehicles in developing countries, i.e. two-wheelers, auto-rickshaws, cars and buses. The on-board monitoring was carried out on different corridors with varying road geometry. Results revealed that the driving cycle was dependent on the road geometry, with two lane mixed flow corridor having lot of short term events compared to that of arterial road. Vehicular emissions during idling and cruising were generally low compared to emissions during acceleration. It was also found that emissions were significantly dependent on short term events such as rapid acceleration and braking during a trip. Also, the standard emission models like COPERT and CMEM under predicted the real world emissions by 30–200% depending upon different driving modes. The on-road emissions measurements were able to capture the emission characteristics during the micro events of real world driving scenarios which were not represented by standard vehicle emission measured at laboratory conditions.     

Using a chassis dynamometer to determine the influencing factors for the emissions of Euro VI vehicles

In order to explore the influence of different factors on the emissions of heavy diesel vehicles, a chassis dynamometer was used to test and analyze a Euro VI standard heavy-duty diesel vehicle under different load, fuel, driving conditions, and resistance conditions. The full load condition was found to increase NOx emissions by about 0.107 g/km (30%) and the particulate matter (PM) by 0.003 g/km (18%) compared to the empty load condition. Compared with the China V diesel, the NOx emissions of the Beijing VI diesel were reduced by 0.065 g/km (18%), and PM decreased by 0.004 g/km (25%). The HC, CO, PM, and NOx emissions measured during the Chinese World Harmonized Transient Cycle (C-WHTC) were 0.002 g/km (27%), 0.0005 g/km (14%), 0.0024 g/km (15%), and 0.092 g/km (25%) higher, respectively, than those measured during the European Transient Cycle (ETC). The HC, CO, PM, and NOx emissions measured by using the test resistance were 0.002 g/km (28%), 0.001 g/km (25%), 0.003 g/km (18.7%), and 0.09 g/km (25.7%) higher, respectively, than those calculated with the recommended formula.     

圆钢管混凝土柱低周反复加载试验研究

为了研究钢管混凝土柱在低周反复荷载作用下组合材料横截面刚度对其性能的影响,以果园港二期工程上的钢管混凝土柱为原型,对3根钢管混凝土柱进行低周反复加载试验。通过控制试件钢管厚度进行物理模型试验,研究钢管厚度对钢管混凝土柱耗能性能、承载性能、强度退化、刚度退化、延性和变形能力的影响。试验结果表明:随着试件钢管厚度的增加,试件的能量耗散系数与等效黏滞阻尼系数均随之减小,试件的耗能能力随之变弱;钢管厚度越小,钢管混凝土柱试件的耗能性能越好。钢管越厚,对核心混凝土的约束作用就越强,强度退化就越弱,试件塑性变形能力就越好。钢管越厚,外包钢管对核心混凝土约束作用就越强,水平承载能力越高。     

优化造船流程,缩短船台周期

介绍了上船澄西船舶有限公司在推行分段总组造船法,发展预舾装技术、精度造船技术,提高分段、总组进坞(台)及下水前的安装完整性,从而最大限度发挥船坞(台)核心生产资源的作用方面取得的新进展.     

确定大巴山隧道地下水年龄的逆统计模型

本文论述了地下水年龄计算的逆统计模型 (ISM)的原理与方法 ,并将该模型用于大巴山隧道地下水年龄估算。计算显示隧址区地下水平均年龄介于 4 5～ 75年之间 ,南坡 (5 5～ 75年 )高于北坡 (4 5～ 6 0年 )说明后者的水力传导性优于前者。该模型既考虑了基岩裂隙介质中地下水流普遍存在的水动力弥散作用的影响 ,又能使地下水年龄计算较之传统的同位素数学物理模型更为简便 ,具有实用价值。     

改进的双工质平行复合循环燃气轮机循环分析

分析了改进的双工质平行复合循环燃气轮机装置性能特点，给出模型和一些计算结果。与改进前的装置效率、比功比较，该装置部套少，成本低，易于利用传统的燃气轮机改装，具有良好的发展前景。     

舰船装备寿命周期费用控制与管理

从舰船装备的寿命周期费用控制与管理入手，分析了外军在舰船装备研制过程中对寿命周期费用进行控制和管理的方法。同时结合我国舰船装备研制过程中寿命周期费用控制和管理的情况，阐述了我国在舰船研制过程中进行寿命周期费用控制和管理的对策。     

基于Buck-Boost变换方式的逆变器

提出了一种基于Buck-Boost变换方式的逆变器。它能实现输出电压高于输入侧直流电压,克服在传统桥式逆变器拓扑中输出电压低于输入侧直流电压而造成的直流电压利用率低的问题。通过改变一个周期内的占空比,以改变单个双向Buck-Boost变换器的输出电压。两个相位相差180°的双向Buck-Boost变换器的输出电压相减即可得到较为理想的单相正弦波;三个相位相互相差120°的双向Buck-Boost变换器可实现三相逆变。可采用SPWM控制功率管的关闭与导通,控制方式采用外环电压环内环电流环的双环控制。仿真结果验证了提出的正弦波逆变器的可行与有效。