Computer simulation of thermochemical treatments: modelling diffusion and precipitation in metals

IntroductionThermochemicaltreatmentsarewidelyusedtoimProvethemechanicalprOPertiesofmetalliccomPonents.ForexamPle,inthecaseofsteel,hightemPeraturediffusionofcarbonand/ornitrogCnleadstoanincreaseofhardnessnearthesurface,aswellastolocalcompressiveresidualstfCsses.Bothcontributetoanincreaseofthelifetimeofthecomponent.Modellingdiffusioncanbeconsideredasrelativelystraightforward,sincethegoverningequationsarewellestablished.However,onemustaccountforthefactthatduringdiffusion,precipitationmayoccur…     

Has heavy vehicle tolling in Europe been effective in reducing road freight transport and promoting modal shift?

Transportation - During the last few decades, the European Union has promoted distance-based charges on heavy goods vehicles for the use of main roads as a means of funding the infrastructure and...     

Managing a smart bicycle system when demand outstrips supply: the case of the university community in Seville

Of the many public initiatives used to promote the use of bicycles in the urban environment, the one that has achieved the most spectacular results in a short period of time is the public bicycle hire system. The experience of Seville is one of the most successful internationally, where 6.6 % of mechanised trips were being made by bicycle within 30 months. This paper analyses this experience in the university community, which represents one-third of system users. We conclude that the people who are most satisfied with the system are those who use it for leisure and recreation activities, non-residents of the city, more environmentally aware people and those who have no alternative mode of transportation. Their satisfaction is also closely linked to their appreciation of the bicycles’ level of comfort, the ease with which users can hire bicycles and return them and the small amount of paperwork involved required to sign up for the system. However, user appreciation has fallen over time because the system’s rapid success has caused it to become overloaded. This experience therefore provides one main lesson: the system’s success can result in eventual difficulties.     

LUTI operational models review based on the proposition of an a priori ALUTI conceptual model

ABSTRACT

This paper focuses on understanding to what extent the components of LUTI models and their mutual interactions are conceptually represented by eight operational LUTI models. This is important for the understanding of LUTI models’ mechanisms, firstly because it may reduce communication barriers between planning communities, secondly because it may help us understand the models’ applicability, and thirdly it may highlight the models’ shortcomings and point for future research. We present a discussion about what subsystems should be considered for LUTI modelling, from which we derived an “a priori” conceptual ALUTI model (incorporating Activities, besides Land Use and Transport). By comparing the rationale behind each model with this conceptual model, we establish the basis for our review, focussing on whether these models incorporate the ALUTI components, its inner workings and the relationships between these components. Results indicate three main limitations of the reviewed models. First, models not always adequately include all the components of the a priori ALUTI model. Second, the ALUTI subsystems’ internal functions are not explicitly modelled in several of the models reviewed, making it difficult to evaluate how planning decisions affect the subsystem. Third, only few models recognise all mutual interactions, especially in respect to the Activity subsystem.     

关于铁路运输景气指数的研究

为适应我国铁路运输市场逐步形成和发展的需要，提出用运输扩散指数来反映当前铁路运输市场的波动方向，用运输综合指数反映铁路运输市场的波动程度。它们分别从定性和定量的角度综合各种监测指标的信息，为铁路运输企业的决策提供定量依据。     

装卸时间与滞期费

从滞期费争议所涉及的滞期费的性质、装卸时间起算的认定等几个重要方面着手,援引英美法体系下关于滞期费的理论和立法精神,结合案例阐述航次租船业务中与滞期费相关的一些法律问题。     

An agent‐based simulation model to assess the impacts of introducing a shared‐taxi system: an application to Lisbon (Portugal)

This paper presents a new concept of urban shared‐taxi services. The proposed system has a new organisational design and pricing scheme that aims to use the capacity in traditional taxi services in a more efficient way. In this system, a taxi acting in ‘sharing’ mode offers lower prices to its clients, in exchange for them to accept sharing the vehicle with other persons who have compatible trips (time and space). The paper proposes and tests an agent‐based simulation model in which a set of rules for space and time matching between a request of a client and the candidate shared taxis is identified. It considers that the client is only willing to accept a maximum deviation from his or her direct route and establishes an objective function for selecting the best candidate taxi. The function considers the minimum travel time combination of pickup and drop‐off of all the pool of clients sharing each taxi while allowing to establish a policy of bonuses to competing taxis with certain number of occupants. An experiment for the city of Lisbon is presented with the objectives of testing the proposed simulation conceptual model and showing the potential of sharing taxis for improving mobility management in urban areas. Results show that the proposed system may lead to significant fare and travel time savings to passengers, while not jeopardising that much the taxi revenues. Copyright © 2014 John Wiley & Sons, Ltd.     

Effectiveness of safety-based incentives in Public Private Partnerships: Evidence from the case of Spain

Many countries around the world are implementing Public–Private–Partnership (PPP) contacts to manage road infrastructure. In some of these contracts the public sector introduces economic incentives to the private operator to foster the accomplishment of social goals. One of the incentives that have been introduced in some PPP contracts is related to safety in such a way that the better the safety outcome the greater will be the economic reward to the contractor. The aim of this paper is at identify whether the incentives to improve road safety in highway PPPs are ultimately effective in improving safety ratios. To this end Poisson and negative binomial regression models have been applied using information from highway sections in Spain. The findings indicate that even though road safety is highly influenced by variables that are not much controllable by the contractor such as the Average Annual Daily Traffic and the percentage of heavy vehicles, the implementation of safety incentives in PPPs has a positive influence in the reduction of fatalities, injuries and accidents.     

Comparative performance of alternative humanitarian logistic structures after the Port-au-Prince earthquake: ACEs,PIEs, and CANs

The paper analyzes the performance of different post-disaster humanitarian logistic structures that arose in response to the Port-au-Prince earthquake of January 12th, 2010. Based on field work conducted by the authors, the paper defines a typology of structures; assesses their relative performance in terms of delivering relief aid; and identifies the causes that explain the differences between them. Three structures are defined for comparative purposes: Agency Centric Efforts (ACEs), Partially Integrated Efforts (PIEs), and Collaborative Aid Networks (CANs). These structures differ to the extent to which they are integrated with the local social networks during the relief effort. Representative examples were analyzed to illustrate their inherent strengths and weaknesses, and reach conclusions of general applicability. The authors strengthen the analyses with discussions of “comparables,” i.e., other cases not fully discussed in the paper that shed additional light onto the performance of the structures.The paper’s analyses are based on dozens of interviews, both formal and informal, conducted with individuals directly involved in the relief effort, complemented with critical analyses of news accounts, and reports produced by the agencies involved. Based on its chief findings, the paper makes policy recommendations to maximize the effectiveness of future relief distribution efforts in response to disasters of various sizes.