New method for predicting full-scale power performance of pumpjet propulsion system based on statistical learning北大核心CSCD

[目的]针对“适配于螺旋桨的船尾线型+泵喷推进器”构成的船舶泵喷推进系统,提出一种基于统计学习的实船快速性预报新方法。[方法]以某大型水面船舶泵喷推进系统为对象,通过神经网络学习典型推进泵的推力系数图谱曲线,综合运用船-桨配合时的K_(T)-J曲线和船体-喷泵配合时的推力特性曲线,建立“仅需船舶阻力曲线就能实现船舶泵喷推进系统实船快速性预报”的新方法,并基于船模阻力试验、泵喷模型敞水试验及船体-泵喷自航试验的测量换算结果对实船推进性能的预报结果开展精度校验。[结果]校验结果表明:在航速18~30 kn范围内,船舶泵喷推进系统的自航转速、推力和功率的预报误差可控制在5.4%以内,其中设计航速附近的误差甚至小于2%;船体-泵喷的相互作用程度介于船-桨与船体-喷泵之间且幅值相对较小,推力减额系数为趋向于0的极小值,故船舶泵喷推进系统是介于桨轴推进系统和喷水推进系统之间的产物。[结论]该预报方法有利于提升船舶泵喷推进系统实船快速性预报的能力,可为新型舰艇泵类推进系统总体设计/研究提供参考。     

Sentiment analysis of popular-music references to automobiles, 1950s to 2010s

In recent years, there has been a scholarly debate regarding the decrease in automobile-related mobility indicators (car ownership, driving license holding, VMT, etc.). Broadly speaking, two theories have been put forward to explain this trend: (1) economic factors whose impacts are well-understood in principle, but whose occurrence among young adults as a demographic sub-group had been overlooked, and (2) less well-understood shifts in cultural mores, values and sentiment towards the automobile. This second theory is devilishly difficult to study, due primarily to limitations in standard data resources such as the National Household Travel Survey and international peer datasets. In this study we first compiled a database of lyrics to popular music songs from 1956 to 2015 (defined by inclusion in the annual “top 40”), and subsequently identified references to automobiles within this corpus. We then evaluated whether there is support for theory #2 above within popular music, by looking at changes from the 1950s to the 2010s. We demonstrate that the frequency of references to automobility tended for many years to increase over time, however there has more recently been a decline after the late 2000s (decade). In terms of the sentiment of popular music lyrics that reference automobiles, our results are mixed as to whether the references are becoming increasingly positive or negative (machine analysis suggests increasing negativity, while human analysis did not find a significant association), however a consistent observation is that sentiment of automobile references have over time become more positive relative to sentiment of song lyrics overall. We also show that sentiment towards automobile references differs systematically by genre, e.g. automobile references within ‘Rock’ lyrics are in general more negative than similar references to cars in other music genres). The data generated on this project have been archived and made available open access for use by future researchers; details are in the full paper.

     

城际铁路CTC中自动折返功能设计与实现

针对提升城际铁路运营效率的迫切需求,在调度集中系统中叠加自动折返功能是一项关键优化内容。以珠三角城际铁路为背景,着重介绍了调度集中系统设计、优化阶段自动折返功能的具体思路与方案,详细描述了折返计划线绘制、车组管理、运营计划发送、折返进路自动办理、自动折返计划等关键环节的实现方法,对实际工程应用提供参考。     

Prevalence of alternative processing rules in the formation of daily travel satisfaction in the context multi-trip,multi-stage,multi-attribute travel experiences

Transportation - Requesting respondents to provide satisfaction ratings for multi-stage trips or daily travel experiences implies they have to value each stage, respectively trip, based on memory...     

Numerical simulation on truncated oval-nosed projectile penetrating into stiffened plate北大核心CSCD

[Objectives]In this paper, the numerical simulation method is used to study the anti-penetration performance and energy absorption mode of a stiffened plate, as well as the influence of different stiffened bars on the flight attitude of the projectile body.[Methods] Finite element software LS-DYNA is used to simulate the process of a truncated oval-nosed projectile penetrating a stiffened plate, and the results of the numerical simulation are compared with an experiment to verify the reliability of the numerical simulation method. The momentum method and mass equivalence method are used to predict the residual velocity of the projectile, and the applicability of different theoretical methods within different velocity ranges is compared. The deformation energy of different regions of the stiffened plate is then extracted to analyze the influence of the initial velocity of the projectile body on the energy absorption mode of the target plate. Finally, the structure of the stiffeners is changed and the influence of the relative position of the stiffeners on the penetration attitude of the projectile body is analyzed.[Results]The results show that the mass equivalence method is more accurate than the momentum method in predicting the residual velocity of the stiffened plate when the initial velocity of the projectile body is in the range of 300–900 m/s. The ratio of the deformation energy of the stiffened plate to the energy loss of the projectile body decreases with the increase of the initial velocity of the projectile body. The effect of a T-stiffened plate on trajectory is greater than that of a rectangular-stiffened plate.[Conclusions]The related calculation method and research results have certain reference value for research and engineering application surrounding the anti-penetration of stiffened plates. © 2023 Chinese Journal of Ship Research. All rights reserved.     

Fault diagnosis of marine diesel engine intake and exhaust system based on dynamic feature fusion北大核心CSCD

[目的]船舶系统由多设备的复杂机构组成,各组件参数具有动态性和非线性的特点,所以故障诊断过程复杂。为提高诊断效率,提出一种动态特征融合方法。[方法]利用分形理论、动态理论及核主元分析(KPCA)法对系统状态数据进行重构、映射及筛选,得到主元特征数据矩阵,求得平方预测误差(SPE)及相应的控制限,构建出基于船舶柴油机进排气系统健康数据的离线监测模型,利用该模型对系统进行故障诊断分析。为验证模型的有效性,选取某船舶柴油机进排气系统的故障数据进行验证分析。[结果]结果表明,动态特征融合分析方法可有效实现对系统动态非线性状态数据的精确分析,实现对系统故障的高效分析和诊断。与KPCA及支持向量机(SVM)方法相比,所提方法具有更好的故障诊断性能。[结论]该方法可实现船舶柴油机进排气系统故障的检测和诊断,提升系统运行的可靠性和安全性。     

Determinants of airport retail revenue: a review of literature

ABSTRACT

As the airport retail industry continues to grow due to increasing travel demands, airport operators are increasingly developing their retail revenue potential to ensure financial viability. This study aims to provide a review of airport retail literature and identify the salient factors associated with passenger shopping behaviour. The paper presents a review of contemporary airport retail literature, covering a total of 50 studies from 1998 to 2018. The review identified 26 factors, which could broadly be grouped into five categories: airport/operator related; passengers' demographic related; passengers’ travel related; passengers’ psychological related and passengers’ resources related. In addition to providing a summary of the statistically significant factors across studies, the review identifies and discusses potential approaches for future research. These include the importance of considering both “to spend or not” decision and how much to spend and how most empirical studies focussed on the former; the gap in empirical analysis on the impact of airport terminal design layout on retail performance; and the gap in application of general consumer shopping behavioural models to airport retail problems. The paper concludes with the suggestion that we can build on the existing studies to develop a hybrid approach to solve several of the identified gaps simultaneously.     

沪昆高铁防灾系统改造与优化

通过统计告警分布,对高铁防灾设备电源类和网络类告警的原因、特点进行分析和判断,并给出处理和减少此两类告警的思路和实施方案。