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Publicações

2017

Affordable LTE Network Benchmarking Based on Transport Fleets

Autores
Dionisio, R; Marques, P; Marques, H; Alves, T; Pereira, L; Silva, F; Ribeiro, J;

Publicação
PROCEEDINGS OF 2017 4TH EXPERIMENT@INTERNATIONAL CONFERENCE (EXP.AT'17)

Abstract
To gain competitive advantage in today's mobile market, cellular network testing, monitoring and improving customer experience is crucial. Today independent benchmarking companies are hired by mobile operators to run drive tests in a certain geographical areas. The high cost for running these tests results in a low frequency of execution, typically this benchmarking is executed no more than two or three times per year, which is not sufficient to follow the dynamics of an LTE network in a dense urban area. The majority of the drive testing costs come from the car, driver, and the in-car technician. Another approach is to take advantage of existing transportation companies to carry on network benchmarking services to Mobile Network Operators. Unattended measurement nodes can be deployed in existing transportation fleets without the need for dedicated field personnel, reducing the cost of testing up to 70%. This demo uses nodes placed in buses, available in several cities in Europe, to create and validate an automatic LTE network benchmark. The tool allows an easy comparative analyses of mobile network quality of Service and quality of experience parameters based on the operators raw data.

2017

Fast and Fully Automatic Left Ventricular Segmentation and Tracking in Echocardiography Using Shape-Based B-Spline Explicit Active Surfaces

Autores
Pedrosa, J; Queiros, S; Bernard, O; Engvall, J; Edvardsen, T; Nagel, E; D'hooge, J;

Publicação
IEEE TRANSACTIONS ON MEDICAL IMAGING

Abstract
Cardiac volume/function assessment remains a critical step in daily cardiology, and 3-D ultrasound plays an increasingly important role. Fully automatic left ventricular segmentation is, however, a challenging task due to the artifacts and low contrast-to-noise ratio of ultrasound imaging. In this paper, a fast and fully automatic framework for the full-cycle endocardial left ventricle segmentation is proposed. This approach couples the advantages of the B-spline explicit active surfaces framework, a purely image information approach, to those of statistical shape models to give prior information about the expected shape for an accurate segmentation. The segmentation is propagated throughout the heart cycle using a localized anatomical affine optical flow. It is shown that this approach not only outperforms other state-of-the-art methods in terms of distance metrics with a mean average distances of 1.81 +/- 0.59 and 1.98 +/- 0.66 mm at end-diastole and end-systole, respectively, but is computationally efficient (in average 11 s per 4-D image) and fully automatic.

2017

Prior education and entrepreneurial intentions: the differential impact of a wide range of fields of study

Autores
Teixeira, AAC; Forte, RP;

Publicação
REVIEW OF MANAGERIAL SCIENCE

Abstract
Studies on entrepreneurial intentions often neglect the heterogeneity of individuals' education background. This paper develops an integrated intention-based framework and analyzes the impact of fields of study on entrepreneurial intentions. Based on a sample of 2423 final-year students, enrolled in 32 fields of study, and resorting to logistic estimations, we find that, beside the attitude towards starting a business, fields of study, considered at a highly detailed level, are relevant (direct and indirect) predictors of entrepreneurial intention. We unambiguously show that there is a huge hidden potential for new venture creation in fields of study related to creative and leisure activities (e.g., Arts and humanities, or, more specifically, Literature and linguistics, History and archaeology, Audio-visual techniques and media production, Sports, and Architecture and town planning), Law, and Health (most notably, Pharmacy and Veterinary). Significant differences in the level of intention between students of different fields of study indicate that universities should more extensively focus entrepreneurship education on students in other subject area than business or engineering/technology sciences.

2017

Hybrid Time Triggered Protocol for Home Wireless Communications

Autores
Rodrigues, EMG; Godina, R; Pouresmaeil, E; Catalao, JPS;

Publicação
2017 1ST IEEE INTERNATIONAL CONFERENCE ON ENVIRONMENT AND ELECTRICAL ENGINEERING AND 2017 17TH IEEE INDUSTRIAL AND COMMERCIAL POWER SYSTEMS EUROPE (EEEIC / I&CPS EUROPE)

Abstract
During the last few years an increasing focus has been made by the research community in utilizing wireless sensor networks (WSNs) in an abundant variety of different applications. Such types of sensor networks are usually supplied by non-rechargeable batteries in order to reduce the expenses. Multi-hop wireless sensor networks frequently utilize a time-division multiple-access (TDMA) plan with the purpose to systematically gather data from various positions of an extended region. The proposed access methods for the Medium Access Control (MAC) in this study combine hybrid proprieties. The proposed MAC specifies that in a given time interval the access to the medium has to be entirely free and without restrictions between the exterior nodes. While this event lasts, the nodes compete for a slot in the network. The proposed methodology corresponds to time-division hybrid multiple-access (TDHMA).

2017

Metrics of Evolving Ego-Networks with Forgetting Factor

Autores
Sarmento, RP;

Publicação
IJSODIT

Abstract
Nowadays, treating the data as a continuous real-time flux is an exigence explained by the need for immediate response to events in daily life. We study the data like an ongoing data stream and represent it by streaming egocentric networks (Ego-Networks) of the particular nodes under study. We use a non-standard node forgetting factor in the representation of the network data stream, as previously introduced in the related literature. This way the representation is sensible to recent events in users' networks and less sensible for the past node events. We study this method with large scale Ego-Networks taken from telecommunications social networks with power law distribution. We aim to compare and analysis some reference Ego-Networks metrics, and their variation with or without forgetting factor.

2017

Mobile payments adoption in public transport

Autores
Fontes, T; Costa, V; Ferreira, MC; Li, SX; Zhao, PJ; Dias, TG;

Publicação
3RD CONFERENCE ON SUSTAINABLE URBAN MOBILITY (3RD CSUM 2016)

Abstract
Nowadays, mobile phones are ubiquitous systems of our society. Nevertheless, the adoption of this technology to perform mobile payments, namely in public transport, was only implemented in a few number of transport networks. Thus, this paper aims to understand which are the main factors that may influence the adoption of mobile payments in public transport. For this purpose, a survey was applied to different groups of population. The study was conducted on the public transport networks of a medium-sized metropolitan area (Oporto-Portugal) and of a big-sized metropolitan area (Beijing-China). The evaluation results of the current services of purchase and validation of public transport tickets almost never show significant statistical differences (p>0.05) for the traditional variables used by the literature. This is particularly true for age. Nevertheless, some mobility factors can sometimes play an important role in the assessment of ticketing systems. Moreover, although the high differences between the ticketing systems in both cities, Chinese and Portuguese have a similar opinion about the systems implemented in their cities. Still, Chinese reveal a higher motivation to adopt the new ticketing system. In general, such system is greatly accepted by the respondents and the potential market is expected to be high (30-68%). Although this technology cannot replace the traditional systems, it can contribute to increasing the overall efficiency of the transport networks. The improvement of the passengers' appraisal, the reduction of operational and the maintenance costs of transport operators are the network impacts most expected. Convenience and time saving are the main advantages mentioned while questions about privacy, interaction and reliability are stated as the main concerns to adopt it. (C) 2017 The Authors. Published by Elsevier B.V.

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