Clustering of Gaussian Random Vector Fields in Multiple Trajectory Modelling

This paper concerns the estimation of multiple dynamical models from a set of observed trajectories. It proposes vector valued gaussian random fields, representing dynamical models and their vector fields, combined with a modified k- means clustering algorithm to assign observed trajectories to models. The assignment is done according to a likelihood function obtained from applying the random field associated to a cluster, to the data. The algorithm is shown to have several advantages when compared with others: 1) it does not depend on a grid, region of interest, grid resolution or interpolation method; 2) the estimated vector fields has an associated uncertainty which is given by the algorithm and taken into account. The paper presents results obtained on synthetic trajectories that illustrate the performance of the proposed algorithm

Fitting Broadband Diffusion by Cable Modem in Portugal

The purpose of this article is to described the evolution of the number of residential subscribers of broadband fixed access by cable modem, in Portugal, on the period from 2000–2009. The pattern of evolution is estimated by fitting several models to the series, namely the following: exponential, Gompertz, Logistic, Bass and Michaelis-Menten. We fit the models to the data by nonlinear least squares, except in the exponential model where the linear version is fitted by ordinary least squares, using the internet freely available program R. This comparative study is in line with many others on the diffusion of technological innovations in the telecommunications sector, where the point is finding out if there is an early or a late take-off phenomenon. The Michaelis-Menten model is introduced for the first time in this approach. It allows to predict the later evolution in the series and reveals a qualitatively different behavior.Broadband, Technological Innovations, Diffusion Growth Models, Nonlinear Least Squares

Recursive bayesian identification of nonlinear autonomous systems

This paper concerns the recursive identification of nonlinear discrete-time systems for which the original equations of motion are not known. Since the true model structure is not available, we replace it with a generic nonlinear model. This generic model discretizes the state space into a finite grid and associates a set of velocity vectors to the nodes of the grid. The velocity vectors are then interpolated to define a vector field on the complete state space. The proposed method follows a Bayesian framework where the identified velocity vectors are selected by the maximum a posteriori (MAP) criterion. The resulting algorithms allow a recursive update of the velocity vectors as new data is obtained. Simulation examples using the recursive algorithm are presented

Earth-Science Education: From all over the World to East-Timor

Earth Science education (ESE) emerges as a relatively new research area and there is an unquestioned need for improving students´ abilities on that field (American Geological Institute, 2008), taking into account that it is important for students’ everyday lives and thus, relevant for scientific literacy. So, the inclusion of a section concerned with this issue, was a very wise decision of the 1st Geological Congress at East-Timor Organising Committee, revealing an up to date vision about education for the XXI century. The paper will be divided in four sections: - Science Education - meaning, epistemology and rationale; - Earth- science-education all over the World in the context of Science Education; - Earth- science education in East-Timor secondary school curriculum; - Earth-science education and challenges for the futur

Alignment of velocity fields for video surveillance

Velocity fields play an important role in surveillance since they describe typical motion behaviors of video objects (e.g., pedestrians) in the scene. This paper presents an algorithm for the alignment of velocity fields acquired by different cameras, at different time intervals, from different viewpoints. Velocity fields are aligned using a warping function which maps corresponding points and vectors in both fields. The warping parameters are estimated by minimizing a non-linear least squares energy. Experimental tests show that the proposed model is able to compensate significant misalignments, including translation, rotation and scaling

Experimental assessment of RRM techniques in 5 GHz dense WiFi networks using REMs

“© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”The increasing acceptance of WiFi has created unprecedented levels of congestion in the unlicensed frequency bands, especially in densely populated areas. This results mainly because of the unmanaged interference and uncoordinated op- eration between WiFi access points. Radio Environment Maps (REM) have been suggested as a support for coordination strategies that optimize the overall WiFi network performance. In this context, the main objective of this experiment is to assess the benefit of a coordinated management of radio resources in dense WiFi networks at 5 GHz band, using REMs for indoor scenarios. It was shown that REMs can detect the presence of interfering links on the network or coverage holes, and a suitable coordination strategy can use this information to reconfigure Access Points (AP) channel assignment and re-establish the client connection, at a cost of diminishing the aggregate throughput of the network. The technique of AP hand-off was tested to balance the load from one AP to another. Using REMs, the Radio Resource Management (RRM) strategy could reconfigure the network to optimize the client distribution among available APs. Although the aggregate throughput is lower after load balancing, the RRM could increase the throughput of the overloaded AP.info:eu-repo/semantics/publishedVersio

O 5G e o IPCB

Atualmente em Portugal, à semelhança do que se passa um pouco por todo o mundo, os operadores móveis estão a implementar no terreno a rede móvel 4G. A tecnologia 4G baseia-se no standard LTE. A rede 4G permite nas melhores condições um acesso à Internet móvel de banda larga até aos 50 Mbps. Com estas velocidades de acesso, complementadas com a tecnologia wireless WiFi conseguimos ter acesso quase instantâneo à informação na ponta dos dedos através dos tablets e smartphones. A evolução da rede tem sido acompanhada com a redução do custo dos telemóveis, cada vez com mais capacidade de processamento e de memória, graças aos avançados tecnológicos da micro-eletrónica. Entretanto, milhares de aplicações móveis, muitas baseadas em Android, apareceram graças à imaginação dos engenheiros de software que tiram partido da capacidade da rede 4G. O tráfego de dados nas redes móveis cresceu 70% só de 2013 para 2014, muito devido às aplicações de vídeo (Youtube) e às redes sociais

Does In Vitro Fertilization Newborns Showed More Risk for Malformations?

info:eu-repo/semantics/publishedVersio

Design of an application for collaboration and interaction with animated content for children in a television ecosystem

Apresentado no contexto do Doctoral Consortium da conferência ACM International Conference on Interactive Experiences for Television and Online Video (TVX 2019)The ongoing research project presented in this paper aims to propose and evaluate models of interaction with audiovisual animated content in an interactive television ecosystem. Through the referred models we aim to understand the extent to which an interactive animation application can encourage the shared participation of children at primary school level in taking an active role while watching TV animation. Here we present the conceptual and empirical methodology adopted to develop the research work and the current state of research.Association of Computer Machinery (Grant)info:eu-repo/semantics/publishedVersio

A Community-Driven Validation Service for Standard Medical Imaging Objects

Digital medical imaging laboratories contain many distinct types of equipment provided by different manufacturers. Interoperability is a critical issue and the DICOM protocol is a de facto standard in those environments. However, manufacturers' implementation of the standard may have non-conformities at several levels, which will hinder systems' integration. Moreover, medical staff may be responsible for data inconsistencies when entering data. Those situations severely affect the quality of healthcare services since they can disrupt system operations. The existence of software able to confirm data quality and compliance with the DICOM standard is important for programmers, IT staff and healthcare technicians. Although there are a few solutions that try to accomplish this goal, they are unable to deal with certain situations that require user input. Furthermore, these cases usually require the setup of a working environment, which makes the sharing of validation information more difficult. This article proposes and describes the development of a Web DICOM validation service for the community. This solution requires no configuration by the user, promotes validation results share-ability in the community and preserves patient data privacy since files are de-identified on the client side.Comment: Computer Standards & Interfaces, 201