2016
Authors
Bakon, M; Papco, J; Perissin, D; Sousa, JJ; Lazecky, M;
Publication
INTERNATIONAL CONFERENCE ON ENTERPRISE INFORMATION SYSTEMS/INTERNATIONAL CONFERENCE ON PROJECT MANAGEMENT/INTERNATIONAL CONFERENCE ON HEALTH AND SOCIAL CARE INFORMATION SYSTEMS AND TECHNOLOGIES, CENTERIS/PROJMAN / HCIST 2016
Abstract
The integrated use of multiple Synthetic Aperture Radar (SAR) platforms for the deformation monitoring via satellite radar interferometry offers several perspectives for investigation of the behaviour of new and ageing structures, such as buildings and infrastructures, under varying or hazardous environment. Spanning almost 24 years of space-borne radar observations, this study aims to perform classical PSInSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) analysis incorporating measurements of ERS, Envisat, TerraSAR-X, Sentinel-1A and Radarsat-2 satellites. The results from the processing of different sensing geometries over Bratislava (Slovakia) urban area are presented, focusing on the description of characteristics associated with the specifics of every satellite platform in use. The discussion over technical feasibility of infrastructure monitoring is accompanied by the outline of possible future needs for the utilisation of the wealth source of information provided by the satellite radar imagery. (C) 2016 The Authors. Published by Elsevier B.V.
2016
Authors
Medeiros, D; Sousa, M; Mendes, D; Raposo, A; Jorge, J;
Publication
22ND ACM CONFERENCE ON VIRTUAL REALITY SOFTWARE AND TECHNOLOGY (VRST 2016)
Abstract
Head-Mounted Displays (HMDs) and similar 3D visualization devices are becoming ubiquitous. Going a step forward, HMD seethrough systems bring virtual objects to real world settings, allowing augmented reality to be used in complex engineering scenarios. Of these, optical and video see-through systems differ on how the real world is captured by the device. To provide a seamless integration of real and virtual imagery, the absolute depth and size of both virtual and real objects should match appropriately. However, these technologies are still in their early stages, each featuring different strengths and weaknesses which affect the user experience. In this work we compare optical to video see-through systems, focusing on depth perception via exocentric and egocentric methods. Our study pairs Meta Glasses, an off-the-shelf optical see-through, to a modified Oculus Rift setup with attached video-cameras, for video see-through. Results show that, with the current hardware available, the video see-through configuration provides better overall results. These experiments and our results can help interaction designers for both virtual and augmented reality conditions.
2016
Authors
Moreira, AC; Silva, PM; Moutinho, VF;
Publication
MARKETING INTELLIGENCE & PLANNING
Abstract
Purpose - The purpose of this paper is to identify and compare different groups of customers' perceptions (i.e. stayers, switchers, and heavy switchers) of several loyalty antecedents such as satisfaction, trust, service quality, switching costs, marketing communication, and loyalty itself. Design/methodology/approach - This study was carried out based on data collected through a questionnaire from 353 telecommunication services users in Portugal and using confirmatory factor analysis (CFA) and analysis of variance. Findings - The three types of customers - stayers, switchers, and heavy switchers - clearly differ among themselves. Stayers differ from switchers regarding their communication efforts perceptions, and from heavy switchers in their loyalty, satisfaction, and trust levels. Switchers differ from heavy switchers in their loyalty levels. Research limitations/implications - Future research should examine differences between customers taking into account the impact of their personality, price sensitiveness, and orientation toward the adoption of new technologies. Practical implications - As there are several differences among stayers, switchers, and heavy switchers, companies should not only recognize the heterogeneity of their customer base, but also target their marketing efforts accordingly. Originality/value - This study is one of the few identifying groups of customers perception's toward service providers. It also complements previous research by splitting them intro three different groups and by analyzing their behaviors across a set of previously unexamined marketing variables.
2016
Authors
Silva, RABE; Arai, NN; Burgareli, LA; de Oliveira, JMP; Pinto, JS;
Publication
IEEE TRANSACTIONS ON RELIABILITY
Abstract
With the increasing importance of software in the aerospace field, as evidenced by its growing size and complexity, a rigorous and reliable software verification and validation process must be applied to ensure conformance with the strict requirements of this software. Although important, traditional validation activities such as testing and simulation can only provide a partial verification of behavior in critical real-time software systems, and thus, formal verification is an alternative to complement these activities. Two useful formal software verification approaches are deductive verification and abstract interpretation, which analyze programs statically to identify defects. This paper explores abstract interpretation and deductive verification by employing Frama-C's value analysis and Jessie plug-ins to verify embedded aerospace control software. The results indicate that both approaches can be employed in a software verification process to make software more reliable.
2016
Authors
Neves Moreira, F; Amorim, P; Guimaraes, L; Almada Lobo, B;
Publication
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH
Abstract
This research aims at tackling a real-world long-haul freight transportation problem where tractors are allowed to exchange semi-trailers through several transshipment points until a request reaches its destiny. The unique characteristics of the considered logistics network allow for providing long-haul services by means of short-haul jobs, drastically reducing empty truck journeys. A greater flexibility is achieved with faster responses. Furthermore, the planning goals as well as the nature of the considered trips led to the definition of a new problem, the long-haul freight transportation problem with multiple transshipment locations. A novel mathematical formulation is developed to ensure resource synchronization while including realistic features, which are commonly found separately in the literature. Considering the complexity and dimension of this routing and scheduling problem, a mathematical programming heuristic (matheuristic) is developed with the objective of obtaining good quality solutions in a reasonable amount of time, considering the logistics business context. We provide a comparison between the results obtained for 79 real-world instances. The developed solution method is now the basis of a decision support system of a Portuguese logistics operator (LO).
2016
Authors
Mukherjee, R; Debattista, K; Bashford Rogers, T; Vangorp, P; Mantiuk, R; Bessa, M; Waterfield, B; Chalmers, A;
Publication
SIGNAL PROCESSING-IMAGE COMMUNICATION
Abstract
A number of High Dynamic Range (HDR) video compression algorithms proposed to date have either been developed in isolation or only-partially compared with each other. Previous evaluations were conducted using quality assessment error metrics, which for the most part were developed for qualitative assessment of Low Dynamic Range (LDR) videos. This paper presents a comprehensive objective and subjective evaluation conducted with six published HDR video compression algorithms. The objective evaluation was undertaken on a large set of 39 HDR video sequences using seven numerical error metrics namely: PSNR, logPSNR, puPSNR, puSSIM, Weber MSE, HDR-VDP and HDR-VQM. The subjective evaluation involved six short-listed sequences and two ranking-based subjective experiments with hidden reference at two different output bitrates with 32 participants each, who were tasked to rank distorted HDR video footage compared to an uncompressed version of the same footage. Results suggest a strong correlation between the objective and subjective evaluation. Also, non-backward compatible compression algorithms appear to perform better at lower output bit rates than backward compatible algorithms across the settings used in this evaluation.
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