对数学建模开放性的认识与实践

数学建模过程的假设、建立、求解、验证、应用等各个环节需要在不断深化、不断循环的过程中改进和突破,它决定了数学建模过程是一个开放的创造过程。     

软CNC在三坐标数控铣床中的研究与应用

针对开放式数控系统的核心技术软CNC,在分析CNC特点和对其分解的基础上,采用Visual C 6.0软件,利用多线程技术,对软CNC进行开发,并通过创建共享内存实现了进程间的通讯。在三坐标铣床中对插补的速度、精度和数据处理进行了测试,研究表明,新开发的软CNC能够满足数控铣床的加工精度要求。     

离岸透空式结构波浪上托力冲击压强计算公式的比较

在前人试验研究的基础上,对几种离岸透空式结构波浪上托力冲击型压强计算公式作了比较和验证,认为用文献[1]计算公式计算的上托力压强与试验结果比较相符,提出采用文献[1]的计算公式计算冲击型压强的建议.     

浅谈船舶明火作业的现场监护

随着船舶明火作业的增多,有资质的施工单位和持证上岗的明火作业施工人员愈显缺乏,由于船舶主管机关现场监督力量不足等原因,使得船舶和施工单位为了经济效益违规作业屡有发生,以致酿成不必要的火灾发生,笔者从三个方面浅释加强船舶明火作业的现场监护.     

软PLC系统开发及其在机床主轴控制中的应用

利用VC 编译器成功开发出了软PLC系统,并实现了PLC程序的编译、运行和基本功能。在开放式数控机床主轴控制中的运行实例表明,所开发的软PLC系统能准确可靠地运行,达到了预期逻辑控制的目的;对软PLC的性能测试表明,软PLC的执行速度较硬PLC有了大幅度提高,为软PLC在开放式数控系统中的应用提供了借鉴。     

波浪力作用下开孔沉箱码头胸墙开裂原因分析

针对开孔沉箱结构现浇混凝土胸墙开裂问题,采取理论分析、数值模拟、现场测试、原型观测、物理模型试验等手段,得出波浪力作用下开孔沉箱上部现浇混凝土胸墙开裂的原因。建立基于互联网+光纤传感技术的开孔沉箱顶板底部波压力在线监测系统,实时获取不同波浪要素下的顶板底部作用力及分布规律,采用物理模型试验测定开孔沉箱在波浪作用下顶板底部受力特征,验证现场监测数据的合理性,并提出工程优化措施的建议。结果表明,波浪力的作用是本工程胸墙开裂的根本原因,应加强早期的防浪工程措施,以减小波浪力的影响。     

福州地铁5号线临近营业线明挖基坑施工技术

随着城市地铁建设的不断发展,临近运营地铁工程的基坑施工已不可避免。施工时如何控制既有地铁结构的变形,并将变形限制在安全运营许可的范围内成为当今重要的研究方向之一。文中结合福州地铁2、5号线金山站工程施工,通过临近营业线车站风险分析,制定合理的施工技术方案,实行科学有效的施工现场管控、现场实时监测及信息反馈等措施,保障基坑施工安全和已开通运营的2号线金山站的车站安全,为今后类似工程施工积累经验。     

Calculation of aircraft fuel consumption and CO2 emissions based on path profile estimation by clustering and registration

In this paper, typical flight paths, fuel burn and carbon dioxide (CO₂) emissions are computed using a rich data set and two estimation approaches: (i) a clustering and landmark registration technique and (ii) a method based on the EUROCONTROL’s Base of Aircraft Data (BADA) performance model. Clustering is employed to extract flight characteristics and organize altitude profiles accordingly. Our flight path and CO₂ emissions analysis focuses on the Climb-Cruise-Descent (CCD) cycle, since different operational conditions during the Landing and Take-off cycle may result in significant deviations in terms of fuel burn and CO₂ emissions and different modeling assumptions and approaches should be adopted. The key features of the CCD cycle are the flight distance, the aircraft type and the flight direction. Path segmentation and landmark registration are employed for path representation and smoothening of discontinuities. The paths estimated by the above method are compared to those obtained by the point mass BADA model. Noticeable deviations in the resulting estimates of the operational characteristics are found. Higher deviations in prediction errors are found in the climb and descent duration and the rate of climb and descent. The typical altitude profiles obtained by the two methods are used to determine fuel burn and CO₂ emissions. The difference in the resulting estimates are less stark; on a fleet-wide level the fuel burn of the relevant typical profiles differ by 7%. Emission maps of the U.S. airspace enabling the identification of critical emission spots including routes, airports, seasons and aircraft type are constructed.     

What type of road pricing scheme might appeal to politicians? Viewpoints on the challenge in gaining the citizen and public servant vote by staging reform

The greatest hurdle facing road pricing reform is political commitment. With rare exception, efforts to introduce significant reform in road pricing, aimed at raising sufficient revenue to ensure that road investment and ongoing maintenance is secured, without an additional impost to users above current outlays, while at the same time reducing traffic congestion, has fallen largely on politically non-supportive ears. The big challenge is to convince politicians (and their advisers) that it is possible to reform road pricing so that users are made better off (at least the great majority) in terms of time spent travelling and monies outlaid, and that government secures growing levels of revenue, but with at least some funds being used to improve public transport and the existing road network. This paper identifies the major issues that make much of the academic research into road pricing somewhat limited in terms of achieving real change. Staging reform is an appealing way forward, but ensuring the order and timing of events to secure progress is the big challenge. We offer some suggestions, including some ideas on new language designed to increase the level of buy in, and recognise that progress through action will require compromises in respect of an ‘ideal’ economically efficient pricing reform agenda.     

兰渝铁路杨家坝隧道穿越浅埋泥石流沟施工技术

杨家坝隧道在DK376+238~+306段以浅埋方式穿越了燕里沟泥石流沟,为了避免隧道暗挖出现拱部坍塌冒顶、突泥突水等安全事故,克服明挖深基坑施工安全风险,采用拱顶明挖、下部暗作、基底加固的方法施工,成功地解决了采用暗挖和明挖施工方法可能出现的各种安全风险,解决了基底承载力不足的难题,为隧道穿越浅埋泥石流沟做了成功的尝试,探索了软弱围岩浅埋隧道新的施工方法。