2014
Authors
Avila, P; Mota, A; Costa, L; Putnik, G; Bastos, J; Lopes, M;
Publication
CENTERIS 2014 - CONFERENCE ON ENTERPRISE INFORMATION SYSTEMS / PROJMAN 2014 - INTERNATIONAL CONFERENCE ON PROJECT MANAGEMENT / HCIST 2014 - INTERNATIONAL CONFERENCE ON HEALTH AND SOCIAL CARE INFORMATION SYSTEMS AND TECHNOLOGIES
Abstract
In the ambit of Distribute/Agile/Virtual Enterprises, the resources/partners selection process is a critical issue in order to guarantee the success of such enterprises. The selection process is complex in the large sense of the word and for that we advocate the necessity of a broker to perform that task, conveniently assisted by a tool. In order to contribute to its construction, this paper presents the resolution of a resources system selection problem, designated by Dependent or Integral Selection Method without Pre-selection of Transport Resources, with two algorithms, an exact solution algorithm and an approximate one. The results demonstrate that the exact solution algorithm limitations can be covered by the approximate algorithm. With those results, the broker has the knowledge to perform the selection with the most adequate algorithm for each case of the problem (depending of the number of tasks and pre-selected resources) addressed in this paper. This paper brings a contribution to broker performance for the selection process. (C) 2014 The Authors. Published by Elsevier Ltd.
2014
Authors
Carreira, R; Patricio, L; Jorge, RN; Magee, C;
Publication
TRANSPORT POLICY
Abstract
Enhancing the travel experience has become a crucial consideration for transportation companies to promote differentiation and customer loyalty. Therefore, transport planners, providers and manufacturers in general are becoming aware of the significance of understanding the passenger experience better, in order to improve transit policies, management and vehicles. The holistic perspective of the travel experience is conceptualized as involving: (1) a thorough set of passenger internal responses (e.g. cognitive and emotional) that are driven by experience factors, some of which are (2) aspects that are not in complete control of the transportation provider, such as waiting areas or the social environment, during (3) all the moments before, throughout and after the trip. Although transportation research has studied the different aspects of transportation quality, empirical studies with such a broad approach to the travel experience and its impact on loyalty are still scarce. This article takes a scale development approach to conceptualize, develop and test a multiple-item scale for measuring the travel experience from the defined holistic perspective, analyzing its perceptual dimensions and outcomes based on a quantitative study with 1226 passengers of a mid-distance bus transportation service. The travel experience scale demonstrates good psychometric properties and consists of 28 items aggregated into seven dimensions or experience factors: individual space, information provision, staffs skills, social environment, vehicle maintenance, off-board facilities, and ticket line service. The study shows that all seven experience factors have a significant impact on customer cognitive, emotional and behavioral responses to the transportation service, highlighting the importance of a broad approach to the study and management of the travel experience. The classical dimensions of individual comfort and vehicle maintenance are the ones with the strongest impact on experience outcomes, showing that transportation providers should maintain a strong focus on providing a good core service. However, other factors such as the social environment have an influence on emotions, which in turn affect loyalty to the transportation provider. These results show the need for a careful study and management of the different aspects of the travel experience, and an integrated design and management of the transport system as a whole.
2014
Authors
Oliveira, M; Santos, V; Sappa, AD;
Publication
Information Fusion
Abstract
Over the past years, inverse perspective mapping has been successfully applied to several problems in the field of Intelligent Transportation Systems. In brief, the method consists of mapping images to a new coordinate system where perspective effects are removed. The removal of perspective associated effects facilitates road and obstacle detection and also assists in free space estimation. There is, however, a significant limitation in the inverse perspective mapping: the presence of obstacles on the road disrupts the effectiveness of the mapping. The current paper proposes a robust solution based on the use of multimodal sensor fusion. Data from a laser range finder is fused with images from the cameras, so that the mapping is not computed in the regions where obstacles are present. As shown in the results, this considerably improves the effectiveness of the algorithm and reduces computation time when compared with the classical inverse perspective mapping. Furthermore, the proposed approach is also able to cope with several cameras with different lenses or image resolutions, as well as dynamic viewpoints. © 2014 Elsevier B.V.
2014
Authors
Cruz, NA; Matos, AC;
Publication
2014 OCEANS - ST. JOHN'S
Abstract
The ability to employ autonomous vehicles to find and track the boundary between two different water masses can increase the efficiency in waterborne data collection, by concentrating measurements in the most relevant regions and capturing detailed spacial and temporal variations. In this paper we provide a guidance mechanism to enable an autonomous vehicle to find and track the steepest gradient of a scalar field in the horizontal plane. The main innovation in our approach is the mechanism to adapt the orientation of the crossings to the local curvature of the boundary, so that the vehicle can keep tracking the gradient regardless of its horizontal orientation. As an example, we show how the algorithms can be used to find and track the boundary of a dredged navigation channel, using only altimeter measurements.
2014
Authors
Sebastião, R; Gama, J; Mendonça, T;
Publication
Prog. Artif. Intell.
Abstract
The ability to collect data is changing drastically. Nowadays, data are gathered in the form of transient and finite data streams. Memory restrictions preclude keeping all received data in memory. When dealing with massive data streams, it is mandatory to create compact representations of data, also known as synopses structures or summaries. Reducing memory occupancy is of utmost importance when handling a huge amount of data. This paper addresses the problem of constructing histograms from data streams under error constraints. When constructing online histograms from data streams there are two main characteristics to embrace: the updating facility and the error of the histogram. Moreover, in dynamic environments, besides the need of compact summaries to capture the most important properties of data, it is also essential to forget old data. Therefore, this paper presents sliding histograms and fading histograms, an abrupt and a smooth strategies to forget outdated data. © 2014 Springer-Verlag Berlin Heidelberg.
2014
Authors
Bizuayehu, AW; Rodrigues, EMG; Santos, SF; Catalao, JPS; Contreras, J;
Publication
2014 IEEE PES GENERAL MEETING - CONFERENCE & EXPOSITION
Abstract
This paper presents an assessment of baseline and higher order grid security criterion applications on current power grid systems, with a focus on their implications in an island context. It considers the European grid code requirements for N-1 and higher order criteria as essential elements for the future deployment of insular distribution grid systems to improve security and stability. Consequently, in the opening section, major facts about island grid topology and current security challenges are illustrated based on a literature review. Afterwards, different approaches applied for security assessment are discussed. A summary of optimal power flow (OPF) approaches is given based on classic problem formulation, and a distribution grid security constrained assessment algorithm is proposed and assessed for island grid context.
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