用于汽车轻量化的结构粘接

人们对车辆的需求趋向于安全性更强、质量更轻且燃料利用效率更高等方面,一种采用了先进高强度钢材、工程塑料及轻质金属的轻型车车体结构也随之打入市场。如果将上述材料单独使用,就会给最大限度减轻车体质量的潜能带来限制。一种以化学基材为基础的结构粘合剂和结构泡沫塑料的应用,巧妙地将上述3种减轻车体质量的材料结合在一起,克服了安全性差．质量难以减轻和加工成本高等难题。     

外生性面神经雪旺氏细胞瘤的形成

为探讨外生性面神经雪旺氏细胞瘤的病理来源及病因 ,对 152 6耳颞骨连续切片进行组织病理学观察。结果发现 :39耳在面神经骨性管裂处显示神经外膜先天性缺损 ,神经主干由此疝出。其中31耳 ,在疝出面神经凸面有明显的雪旺氏细胞增生。这 31耳中 ,有 12耳在卵圆窗上方 ,1耳在面神经第二膝部形成小的外生性雪旺氏细胞瘤。提示 :管裂处神经外膜的先天性缺损是面神经由此疝出的组织解剖学原因。面神经疝出可能是刺激雪旺氏细胞增生 ,以致形成外生性面神经雪旺氏细胞瘤的直接原因。     

Dealing with the efficient allocation of scarce resources at congested airports

The existing slot allocation mechanism, based on the International Air Transport Association (IATA) system and its complementary version of the European Union (EU) regulation, produces rather poor capacity allocation outcomes for congested EU airports since it fails to properly match slots requested with slots allocated to airlines. Inefficiencies during the initial allocation are mainly due to the problem complexity in conjunction to limited decision support available to slot coordinators. On the other hand, substantial inefficiencies give rise to severe slot misuse and unreasonably low utilisation of airport resources running already into scarcity. The objective of this paper is to develop an optimisation-based model implementing the existing EU/IATA rules, operational constraints, and coordination procedures with the ultimate objective to better accommodate airlines’ preferences at coordinated airports through the minimisation of the difference between the requested and the allocated slot times to airlines. The results of the model are assessed and compared vis-à-vis the allocation outcome produced according to current slot coordination practice in three regional Greek airports. The proposed model produces very promising results and demonstrates that there is large room for improvement of the efficiency of the current allocation outcome in a range between 14% and 95%. The discussion of the model results is complemented by a sensitivity analysis highlighting the importance of declared capacity and the magnitude of its influence on slot allocation efficiency.     

Statistical inference on transit route‐level origin–destination flows using automatic passenger counter data

We consider inferring transit route‐level origin–destination (OD) flows using large amounts of automatic passenger counter (APC) boarding and alighting data based on a statistical formulation. One critical problem is that we need to enumerate the OD flow matrices that are consistent with the APC data for each bus trip to evaluate the model likelihood function. The OD enumeration problem has not been addressed satisfactorily in the literature. Thus, we propose a novel sampler to avoid the need to enumerate OD flow matrices by generating them recursively from the first alighting stop to the last stop of the bus route of interest. A Markov chain Monte Carlo (MCMC) method that incorporates the proposed sampler is developed to simulate the posterior distributions of the OD flows. Numerical investigations on an operational bus route under a realistic OD structure demonstrate the superiority of the proposed MCMC method over an existing MCMC method and a state‐of‐the‐practice method. Copyright © 2015 John Wiley & Sons, Ltd.     

The estimation of transport cost functions: a methodological review

Abstract

The ex‐post facto cost of using private finance in roads is examined using a case study approach. The paper focuses on the first eight design, build, finance and operate (DBFO) roads commissioned by the UK Government’s Highways Agency and paid for through a system of shadow tolls. It carries out a financial analysis of the publicly available accounting information from the Highways Agency and its private sector partners for the first 6 years since the start of the 30‐year schemes in 1997. Publicly available financial information about the schemes was found to be limited and opaque. In 3 years, the Highways Agency had paid more than the construction cost. It was unclear whether the payments were higher than expected at financial close. Its private sector partners reported a post‐tax return on capital of 29% and an effective cost of capital of 11% in 2002, twice the cost of public finance. However, operating through a complex web of subcontracting creates additional, undisclosed sources of profit for their parent companies that make it difficult to establish the total cost of using private finance. The paper questions the wisdom of using private finance by providing evidence about the cost, including the cost of risk transfer.     

A dynamic route choice model for public transport networks with boarding queues

Abstract

The concepts of optimal strategy and hyperpath were born within the framework of static frequency-based public transport assignment, where it is assumed that travel times and frequencies do not change over time and no overcrowding occurs. However, the formation of queues at public transport stops can prevent passengers from boarding the first vehicle approaching and can thus lead to additional delays in their trip. Assuming that passengers know from previous experience that for certain stops/lines they will have to wait for the arrival of the 2nd, 3rd, …, k-th vehicle, they may alter their route choices, thus resulting in a different assignment of flows across the network. The aim of this paper is to investigate route choice behaviour changes as a result of the formation and dispersion of queues at stops within the framework of optimal travel strategies. A new model is developed, based on modifications of existing algorithms.     

The VOCO multi-body software in the context of real-time simulation

The railway multi-body software developed for more than 20 years by INRETS (now IFSTTAR), under the name VOCO^®, has been dedicated from the origin to highly nonlinear elements, such as the dry friction dampers of freight bogies and the wheel–rail contact based on measured profiles. A second important step has been the discovery of a particular method in order to simulate on sinuous tracks. In the aim of industrial applications, the specification has always been to reach the goal of real time. Although it is not possible in all the cases, the recent non-Hertzian contact development is allowing real-time simulation to be achieved.     

What’s your type: a multidimensional cyclist typology

Increasing bicycle use for utilitarian trips is a common city objective for health and environmental improvement and congestion reduction, but cyclists react heterogeneously to interventions and infrastructure. Understanding cyclist types helps in comprehending and planning for this diverse population. This study uses data from 2004 surveyed Montreal cyclists to generate a multidimensional cyclist typology based on seven factors derived from 35 variables, mostly proven determinants of the intensity of bicycle usage. The analysis revealed four distinct cyclist types: dedicated cyclists, path-using cyclists, fairweather utilitarians, and leisure cyclists. The cycling frequencies of each group respond differently to potential interventions and vary within commuting rate ranges with apparent minima and maxima. Building a network adapted to different cyclist types and emphasizing its convenience, flexibility and speed, could be an effective strategy to increase cycling mode share and frequency among the various groups. Findings from this study can be of benefit to transportation engineers, planners and policy makers as they help in better understanding the impacts of various interventions on the different groups of cyclists.     

Ship complexity assessment at the concept design stage

An innovative complexity metric is introduced that provides a way to compare similar or different ship types and sizes at the contract design stage. The goal is to provide the designer with this information throughout the design process so that an efficient design is obtained during the first design run. Application to and validation on real passenger ships indicate that there is a significant correlation between the error in an engineer’s judgement of complexity and the cost assessment error. It follows that this tool could be used to improve knowledge of the ship’s complexity at the contract design stage, and even to try to optimise the design if the complexity criteria are not fixed by the shipowners.