Air itinerary shares estimation using multinomial logit models

ABSTRACT

The main goal of this study is the development of an aggregate air itinerary market share model. In order to achieve this, multinomial logit models are applied to distribute the city-pair passenger demand across the available itineraries. The models are developed at an aggregate level using open-source booking data for a large group of city-pairs within the US air transport system. Although there is a growing trend in the use of discrete choice models in the aviation industry, existing air itinerary share models are mostly focused on supporting carrier decision-making. Consequently, those studies define itineraries at a more disaggregate level using variables describing airlines and time preferences. In this study, we define itineraries at a more aggregate level, i.e. as a combination of flight segments between an origin and destination, without further insight into service preferences. Although results show some potential for this approach, there are challenges associated with prediction performance and computational intensity.     

Methodology for Validating Dynamic Origin–Destination Matrix Estimation Models with Implications for Advanced Traveler Information Systems

This paper describes a methodology for validating online dynamic O–D matrix estimation models using loop detector data in large-scale transportation networks. The simulation procedure focuses on travel aspects related to the collective trip structure of users, including the amount and duration of trips between O–D pairs, trip departure rates, average travel time from each origin and combinations of them. The analysis identifies emerging systematic patterns between these factors and issues related to the model performance, including network scale effects. This procedure aims to enhance the usage of prior O–D information based on, e.g. travel surveys, that are typically used in the estimation process. Moreover, it seeks to integrate the validation of dynamic O–D matrix estimation models with strategies for identifying target population groups for online planning and assessment of real-time travel information services within the context of Advanced Traveler Information Systems (ATIS).     

The evolution of urban traffic control: changing policy and technology

Abstract

The history of urban traffic control (UTC) throughout the past century has been a continued race to keep pace with ever more complex policy objectives and consistently increasing vehicle demand. Many benefits can be observed from an efficient UTC system, such as reduced congestion, increased economic efficiency and improved road safety and air quality.

There have been significant advances in vehicle detection and communication technologies which have enabled a series of step changes in the capabilities of UTC systems, from early (fixed time) signal plans to modern integrated systems. A variety of UTC systems have been implemented throughout the world, each with individual strengths and weaknesses; this paper seeks to compare the leading commercial systems (and some less well known systems) to highlight the key characteristics and differences before assessing whether the current UTC systems are capable of meeting modern transport policy obligations and desires.

This paper then moves on to consider current and future transport policy and the technological landscape in which UTC will need to operate over the coming decades, where technological advancements are expected to move UTC from an era of limited data availability to an era of data abundance.     

F-TYPE不但具备了全轮驱动还配备了手动变速器

<正>虽然没有覆盖全部产品,但具有运动风格的四轮驱动系统和6挡手动变速器还是添加进了F-type的产品线在新改款撞豹F-type两门跑车和敞篷跑车的中控台上我们会发现一些新的惊喜,对于捷豹运动性能车的粉丝来说已经很长时间没有看到的装置——手动变速器换挡杆。在今天的高性能汽车市场上换挡拨片占据了主导地位,而捷豹的工程师们和公关部人员相信手动变     

An Active Roll-Moment Control Strategy for Narrow Tilting Commuter Vehicles

An automatic tilt control strategy for a narrow commuter vehicle is described. Such a vehicle would be enclosed like a conventional car but would bank into turns like a motorcycle and so it would feel quite unconventional to drive. The proposed tilt control system uses the steering to tilt the car over like a motorcycle but this is augmented by actively generating a rolling moment about the pivot axis between the tilting upper body and non-tilting base. The provision of this active direct tilt control enables the vehicle to remain upright at low or zero speed and also permits the designer to fine tune the transient roll response. Although it appears complex the proposed tilting control relies on only a few simple sensor measurements, some modest, microprocessor based signal processing and low power, low bandwidth steering and tilt control actuators which might be derived from existing automotive components.     

The role of chemical signals in copepod reproduction

Because the reproductive fitness of a copepod is influenced by its ability to discriminate between conspecific and heterospecific mates, it is important to understand the mechanisms involved in these complex mate-recognition systems. Several lines of evidence suggest that chemical communication plays a role in mate location, recognition and reproduction in copepods. However, the relative importance of chemosensory cues, as well as other factors, including hydromechanical and morphological cues, remains unclear. Some studies show that mating ‘mistakes' occasionally occur in nature, which for species that mate only once, would have considerable effects on fitness. By reducing the likelihood of heterospecific matings, species-specific mate location and recognition chemicals have high adaptive value. The relative importance and molecular characteristics of these chemicals, whether diffusible or contact signals, may explain differences in premating and copulatory behavior observed among different copepod taxa. Current research suggests that both forms of chemical communication significantly influence the reproductive success of copepods. In this review, we summarize examples from the literature that may serve as a means to critically analyze postulated ideas and offer new questions for future study.     

城市交通控制的演变--政策与技术变更

在过去的一个世纪里,城市交通控制始终在演变,以适应日益复杂的政策目标和不断增长的交通需求。一个高效的交通控制系统可以带来很多收益,例如缓解拥堵、提高经济效益以及改善道路安全和空气质量。车辆检测和通信技术方面取得的显著进步为交通控制系统的调控能力带来了一系列阶段性变化：从早期（固定配时）信号控制发展到现代化的集成系统。多种类型的交通控制系统在全球不同地区建设完成,每种系统都有各自的优势和不足。首先通过对比分析目前占据领先地位的商用系统（以及一些较少为人所知的系统）,凸显交通控制系统的关键特征和差异,然后评估目前的交通控制系统是否能实现现代交通政策的职能和需求。最后,探讨了当前及未来的交通政策,以及未来10年交通控制发展的技术性蓝图,指出交通控制有望通过技术进步从有限数据时代迈入大数据时代。