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。     

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.     

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.     

坚定不移抓改革 持之以恒求创新——访湖南龙骧巴士有限责任公司党委书记、总经理赵智勇

湖南龙骧巴士有限责任公司(以下简称龙骧巴士)是长沙市公共交通行业的骨干企业。自2005年公司组建成立以来,在长沙市委、市政府及行业主管部门的大力支持下,在公司全体员工的共同努力下,龙骧巴士坚定不移抓改革,持之以恒求创新,取得了跨越式的发展,为长沙公共客运市场的繁荣、稳定、发展做出了积极贡献。近日,本刊(以下记作"城市公共交通")专访了湖南龙骧巴士有限责任公司党委书记、总经理赵智勇。     

预应力钢筋混凝土T梁桥造价分析与应用

文章根据某省不同地形的高速公路采用预应力钢筋混凝土 T 梁桥结构的造价组成的统计分析， 即对分部工程造价及工程量组成进行分析、 对主要影响技术经济指标的基础工程、 上部构造、 下部构造单位桥梁面积的主要材料消耗和材料价格进行了详细分析， 以及材料价格的涨跌对预应力钢筋混凝土 T 梁桥造价技术经济指标的敏感性， 作为今后在高速公路前期工作中对该类结构快速估算投资提供参考依据。     

动车所电码化二次优化问题

针对动车组在太原动车所瞬间接收反向HU码导致控停的疑难问题,剖析了相关影响因素,分析了电路初次改进后仍存在的不足,提出了电路二次改进方案并付诸实施,解决了原有问题,保证了高铁的正常运营。