船舶参数激励和强迫激励作用下的非线性运动响应

本文应用非线性动力学理论,考虑船舶参数激励和横向强迫激励,研究了船舶的1/2亚谐共振运动。得到了横摇运动失稳条件,提出了横摇运动失稳及船舶倾覆的参数域。     

A hybrid heuristic strategy for liquefied natural gas inventory routing

As liquefied natural gas (LNG) steadily grows to be a common mode for commercializing natural gas, LNG supply chain optimization is becoming a key technology for gas companies to maintain competitiveness. This paper develops methods for improving the solutions for a previously stated form of an LNG inventory routing problem (LNG-IRP). Motivated by the poor performance of a Dantzig-Wolfe-based decomposition approach for exact solutions, we develop a suite of advanced heuristic techniques and propose a hybrid heuristic strategy aiming to achieve improved solutions in shorter computational time. The heuristics include two phases: the advanced construction phase is based on a rolling time algorithm and a greedy randomized adaptive search procedure (GRASP); and the solution improvement phase is a series of novel MIP-based neighborhood search techniques. The proposed algorithms are evaluated based on a set of realistic large-scale instances seen in recent literature. Extensive computational results indicate that the hybrid heuristic strategy is able to obtain optimal or near optimal feasible solutions substantially faster than commercial optimization software and also the previously proposed heuristic methods.     

Plan-based flexible bus bridging operation strategy

Bus bridging has been widely used to connect stations affected by metro disruptions such that stranded passengers could resume their journeys. Previous studies generally assumed that a bus operates exclusively on one bridging route with given frequency, which limits the service flexibility and reduce the operational efficiency. We propose a strategy to instruct buses to operate on predefined bridging routes once they are dispatched from depots. Buses are allowed to flexibly serve different bridging routes. Each bus operates based on a bridging plan that lists the stations to serve in sequence instead of route frequencies. A two-stage model is developed to optimize the bridging plans and their assignments to buses with the objectives that balance the operational priorities between minimizing bus bridging time and reducing passenger delay. A Weight Shortest Processing Time first (WSPT) rule based heuristic algorithm is developed to solve the proposed model. The developed model is further incorporated in a rolling horizon framework to handle dynamic passenger arrivals during the disruption period. The effectiveness of the proposed strategy is demonstrated in comparison with alternative strategies in real-world case studies.     

集装箱船舶的船长应充分注意船舶稳性

本文针对集装箱船舶的驾驶人员在生产实践中就船舶稳性方面可能出现的问题进行了探讨,提出了解决的办法,提请集装箱船舶的船长们注意,以利船员和船舶的安全     

胶轮+导轨式有轨电车动力走行部滚振试验台设计

分析胶轮+导轨式有轨电车动力走行部的导向机理、脱轨机理,介绍电车3种类型的动力走行部导向机构。为研究导轨电车的轮轨关系,对其动力走行部的脱轨机理展开试验研究,设计动力走行部滚振试验台。试验台可以模拟电车空载和满载条件,以及直线、曲线通过工况。通过测量导向轮的横向力、垂向力和垂向位移3个参数,研究分析导轨电车导向、脱轨机理,并建立相关评价标准。试验台为导向机构的优化及电车运行安全的提升提供保障。     

地铁车轮降噪研究

利用轮轨噪声预测模型软件TWINS,以3种典型地铁车轮结构为例,分析车轮直径和制动方式对车轮噪声的影响,并利用各种阻尼措施和基于降低车轮噪声的车轮设计原则,对车轮结构进行优化和降噪研究.研究表明:减小车轮直径会增大车轮噪声声功率级约1.5～2.0 dB;轮盘制动的车轮比踏面闸瓦制动的车轮的噪声声功率级约小7.3 dB;采用三明治阻尼板和双阻尼环结构,可分别将SHL10车轮的噪声声功率级降低约7.8和4.6 dB;各种阻尼措施对NJL2车轮的降噪效果与SHL10车轮类似;采用单阻尼环(焊接接头)结构能将SHL10车轮的噪声声功率级降低约1.8 dB;双阻尼环结构对SHDB车轮的降噪效果明显;车轮结构优化后得到的SHL10O的车轮噪声声功率级比SHI10的车轮噪声声功率级降低2.3 dB,而NJI2O车轮的噪声声功率级比NJL2车轮的噪声声功率级降低1.6 dB.     

铁路机辆设备工程规划研究

铁路机辆设备是承担机车、车辆、动车组检修的场所,是铁路工程重要的内容,为科学合理、经济高效设计机辆设备工程,采用规划方法。通过分析机辆设备工程内容,提出规划设计框架。从中长期铁路网规划、铁路工程建设,以及机辆制造、检修技术等设计依据方面进行详细研究,基于现行有效的工程设计标准,通过测算和理论分析,从布点、功能、关键技术、总体管理4个方面提出规划设计意见,研究成果可有效指导铁路机辆设备工程设计。     

Luster Polish Strengthening Treatment for Raceway Surface of Aeroengine Bearings

A new surface strengthening technology, luster polish strengthening treatment, was proposed to treat the raceway surface of aeroengine bearings (9Cr18Mo) with the centrifugal strengthening machine exclusively designed for luster polish strengthening treatment. The experimental results showed that luster polish strengthening treatment produced a compressive residual stress layer with a depth of over 80 μm below the surface of the bearing raceway, and thus effectively removed the metamorphic layer in the raceway surface. After luster polish strengthening treatment, the average surface hardness of the aeroengine bearing raceway was increased from 61.02 HRC to 63.01 HRC, the surface roughness was reduced from 0.06 μm to 0.03 μm, and the contact fatigue life of the aeroengine bearings was improved by about 90%, with the dispersion of fatigue life being reduced remarkably. Theoretical calculation result agrees with that obtained by experiment.     

The optimal dispatching of taxis under congestion: A rolling horizon approach

Taxis make an important contribution to transport in many parts of the world, offering demand‐responsive, door‐to‐door transport. In larger cities, taxis may be hailed on‐street or taken from taxi ranks. Elsewhere, taxis are usually ordered by phone. The objective of a taxi dispatcher is to maximize the efficiency of fleet utilization. While the spatial and temporal distribution of taxi requests has in general a high degree of predictability, real time traffic congestion information can be collected and disseminated to taxis by communication technologies. The efficiency of taxi dispatching may be significantly improved through the anticipation of future requests and traffic conditions. A rolling horizon approach to the optimisation of taxi dispatching is formulated, which takes the stochastic and dynamic nature of the problem into account. Numerical experiments are presented to illustrate the performances of the heuristics, taking the time dependency of travel times and passenger arrivals into account.     

抛石强夯与蓝派冲击压实在填海路基工程中的应用

本文研究了点夯、蓝派冲击式压实机的工作原理,结合工程实例,软基处理环境复杂,施工技术要求高,难度大等特点,阐述了该工艺的施工原理、施工方法、质量控制措施,并对该工艺的优点进行了总结,此方案的实施对填海路基的实际施工具有重要的指导性意义。