An Exploratory analysis of flight delay propagation in China

Delay propagation is the flight departure delay caused by the arrival delay of pre-segment flight. Chinese airline market has suffered very poor on-time performance (OTP) in recent years. It is, however, unclear whether delay propagation prevails as one major source for such problem. This study first aims to empirically quantify delay propagation in the Chinese airline market. Specifically, we shed light on heterogenous levels of delay propagations across different airports and airlines. Then, the distinct delay propagation patterns in China are also discussed and compared with other developed airline markets (e.g., the US and Europe). Our estimation is based on OTP data for over 12 million Chinese flights covering the 2015–2017 period. Specifically, it is found that 10 min arrival delay of pre-segment flight within 1 hr before the departure lead to an average of 7.49 mins delay propagation for subsequent departure flight. Arrival delay of earlier pre-segments (1–2 and 2–3 hr before the departure) leads to much less delay propagation, due to longer ground buffer. Chinese airlines arrange longer ground and flight buffer than that of the US airlines to prevent the delay propagation from accumulating along the subsequent flights in a day. Thus, unlike the US market, delay propagation is not the major reason for poor OTP in China. In addition, delay propagation is less prevailing at the Chinese hub airport. This is because China has relied on point-to-point network, which does not require sophisticated schedule coordination. And the local passengers at these Chinese hub airports have higher time value such that the Chinese airlines also try to improve OTP at these hub airports to better serve these lucrative but time-sensitive local passengers. Unlike the European LCCs, Spring Airlines, the largest low-cost carrier (LCC) in China, outperforms major full-service carriers (FSCs) in controlling delay propagation. This finding may also apply to other Northeast Asian LCCs sharing common operational characteristics as Spring Airlines. Last, we find that airlines purposely tolerate moderate departure delays of up to 15 min, which is the threshold that defines delays, no matter whether the pre-segment flight arrives late or on-time. The relevant policy and managerial implications are also discussed.     

基于车辆数据的k近邻联合概率数据关联算法

在交通场景中采用一些预警措施能够有效地减少交通事故发生。例如，对车辆轨迹进行跟踪并预测车辆的驾驶行为，就是一个常用的预警方法。在对车辆进行跟踪的过程中，数据关联是很重要的部分，它可以对车辆的观测点和轨迹进行关联，从而更新车辆的轨迹，完成跟踪过程。在此背景下，提出了一种新的数据关联算法，即k近邻联合概率数据关联算法(k Nearest Neighbor-Joint Probability Data Association,kNN-JPDA)。实验结果表明，该算法能够较好地解决在交通场景下车辆数据的数据关联问题，在精度以及运行效率方面都有所提高。     

阵列天线在UXB系统标校中的应用

测量船基地现有标校塔与测量船距离只有980 m,无法满足高频段统一X频段（UXB）系统天线的远场标校距离条件。针对这一难题,提出了一种利用阵列天线合成准平面波的方法,实现在近场距离条件下的远场标校。在现有标校塔上架设安装阵列天线设备,利用16个单喇叭天线组成4×4的天线阵,并通过控制单个喇叭天线元的幅度和相位,使得传播到测量船UXB天线口面处由阵列天线合成的电磁波是准平面波,满足X频段天线远场标校要求。综合运用最优化理论和遗传算法,对阵列天线元的幅度和相位权值进行调节和优化,使得合成的电磁波更为接近准平面波。计算机仿真实验和外场条件下的实际测试均验证了该方法生成的准平面波能够满足UXB天线远场标校要求。     

网络段子:微传播时代的全民狂欢

藉由"微媒介",网络段子作为新媒体写作家族的成员,因其短小精悍、发表无限制、娱乐性强的特征,契合了当下快节奏的生活,迅速形成全民写作热潮。它直面现实,消解权威,颠覆传统,调侃生活,娱乐大众,成为微传播时代大众精神消费的狂欢。     

Feminism’s fourth wave: a research agenda for marketing and consumer research

Abstract

Three waves of feminism each reveal a very different relationship with marketing. This commentary considers these relationships in the light of what is now frequently being hailed as the fourth wave, a resurgence of feminism that is driven by younger women who harness the power of the Internet and social media to challenge gender inequity. The commentary looks at what distinguishes the fourth wave from its predecessors and highlights key areas in marketing and consumer research where feminist perspectives are sorely required.     

心理健康教育视域下的校园文化景观教学——以福建商业高等专科学校为例

在校园文化建设中,景观建设是其基本内容。商专校园文化景观贯穿继承与弘扬"闽商精神"的根本理念,将几大文化板块相融通,构造出丰富多彩的内容。探讨校园文化景观与心理健康教育的关系,结合相关的基础理论,分析校园文化景观对心理健康教育的多重积极作用,使心理健康教育的情境化教学方式落到实处,有益于心理健康教育的良性发展,对深化高校心理健康教育的多样化途径的认识与理解也有借鉴作用。     

约束稀疏脉冲反演在GX气田开发中的应用研究

GX气田北部地区构造、断层特征较为复杂,地质建模较困难,而约束稀疏脉冲反演是一种基于地震道的反演方法,它是在波阻趋势的约束下,用最少的反射系数脉冲达到合成记录与地震道的最佳匹配。该方法对初始模型依赖性较小,中高频部分不受初始模型的影响,其反演结果能忠于实际地震资料,分辨率与地震资料接近,保真度高。以GX气田为例,通过约束稀疏脉冲反演技术对GX气田开展储层预测,其反演结果与实测井曲线吻合较好,能客观反映地质体在横向上的变化特征,该方法适用于储层横向变化快和非均质性较强的少井区块。     

低应变反射波法在PHC管桩完整性检测中的应用分析

根据低应变反射波法检测高强度预应力混凝土管桩(PHC)桩身完整性的原理,通过具体工程实例对低应变反射波检测PHC管桩有关问题进行了分析探讨。     

Granular institutional investors and global market interdependence

We study the propagation of global investment risk across markets through the granular view of institutional investors. Applying the conditional value-at-risk estimation to micro-level weekly observations of international mutual funds between 2003 and 2011, we find that idiosyncratic shocks to large institutional investors explain both aggregate market risk and cross-market risk interdependence. Conditional on the US capital markets being in financial distress, idiosyncratic shocks to the top 10% largest funds investing in the US explain about 40% of the risk fluctuations in other non-US markets. The findings are also economically and statistically significant for the top largest funds investing in non-US markets, with the effects becoming especially large during the global financial crisis of 2007–09. These results are robust after controlling for common risk factors and applying alternative measures of idiosyncratic shocks.     

产品市场竞争与资本结构的战略决策

“有限负债效应”理论指出,企业提高财务杠杆导致了产出的增加,但很多实证研究却难以支持这一结论。本文分析了在上游企业外部规模效应较强的情况下,企业债务融资战略效应为负的理由,证明了不存在外部规模效应是债务融资战略的重要条件。企业的融资行为深受财务危机的影响,其中企业规模、产业集中度、产品专用性、R&D支出和行业前景是决定财务危机成本大小的关键变量,因此,以财务危机成本为依据进行决策,企业会自我限制债务水平。由此,企业资本结构的决策应从产品市场竞争状况去考虑,这对我国企业融资决策有重要意义。