Modelling the Duration of Multihop Paths in Mobile Ad Hoc Networks

Mobile ad hoc networks are characterized by having nodes that are cooperative and communicate without any kind of infrastructure. The mobility and multihop capability of these networks leads the network topology to change rapidly and unpredictably; this aspect must be incorporated in effective models to describe the dynamics of multihop paths.\newline When modeling the duration of multihop paths, a great part of the literature assumes that the links of multihop paths behave independently. This simplifies the modeling and reduces the complexity of computations. However, each link shares a common node with each of its neighbor links, turning the independent link assumption ge-nerally not valid. In this paper, we use a piecewise deterministic Markov model that characterizes the random behaviour of a multihop path not assuming independent links. We obtain the mean path duration of multihop paths and compare the results for the used model with the ones obtained by assuming independent links. Numerical results illustrate that independent link approximation results underestimate the mean path duration, with the most significant differences being observed with low node mobility and higher path durations

Free software and free culture in Higher Education: pipelines and workflows for creative purposes

OpenLab ESEV is a project of the School of Education of the Polytechnic Institute of Viseu (ESEV), Portugal, that aims to promote, foster and support the use of Free/Libre Software and Open Source Software, Open Educational Resources, Free Culture, Free file formats and more flexible copyright licenses for creative and educational purposes in the ESEV's domains of activity (education, arts, media). Most of the OpenLab ESEV activities are related to the teacher education and arts and multimedia programs, with a special focus on the later. In this paper, the project and some activities are presented, starting with its origins and its conceptual framework. The presented overview is intended as background for the examination of the use of Free/Libre Software and Free Culture in educational settings, specially at the higher education level, and for creative purposes. The activities developed with students and professionals generated pipelines and workflows implemented for different creative purposes, software packages used for different tasks, choices for file formats and copyright licenses. Finished and ongoing multimedia and arts projects will be presented as real case scenarios

O Projecto NetInfância e a construção de conhecimento profissional numa licenciatura em Educação de Infância

Numa altura de alteração na formação inicial de educadores de infância que, de novo, realça a relação com a investigação e a produção de conhecimento profissional específico, apresenta-se uma análise de estudos desenvolvidos no âmbito de uma licenciatura que focaram a utilização das tecnologias de informação e comunicação (tic) na educação pré-escolar. A análise orientou-se por preocupações relativas à produção de conhecimento por professores e à necessidade de estudos que apoiem a decisão sobre a utilização das tic na educação pré-escolar. Foram apreciadas as instâncias conceptual, substantiva e metodológica dos estudos, em detrimento de uma revisão de resultados. Destacam-se características de investigação realizada por práticos e de conhecimento pedagógico de conteúdo concretizados por alguns desses estudos, bem como as combinatórias metodológicas e os procedimentos de acesso ao campo bem sucedidos. A criação de espaços de produção de investigação nos novos mestrados pode beneficiar da análise destes processos nessas dimensões

Using Free Software in Higher Education for Creative Purposes: The Case of OpenLab ESEV

OpenLab ESEV is a recent project of the Polytechnic Institute of Viseu’s School of Education that aims to promote, foster and support the use of Free/Libre Open Source Software (F/LOSS) and Free File Formats for creative and educational purposes. During its first year of existence, the project has been particularly active in the fields of document production, software training, and technical support. As an emerging project of use of F/LOSS for creative and artistic purposes, specifically the support to 3D animation students’ projects, we intend to share what we’ve learned by discussing results and some of the changes we want to implement in the near future. The paper includes some core concepts and concerns underlying the project, together with an analysis of the achievements and difficulties, including prefered software packages and workflows and some ongoing students’ work as real case scenarios

A big data approach to explore medical imaging repositories based on DICOM

Medical imaging repositories based on the DICOM format such as Picture Archiving and Communication Systems have a huge potential from a big data perspective. The study reported by this paper aimed to verify on how the big data lifecycle processes, from production to consumption might be implemented to take advantage of the DICOM standard and respective data sources. After identifying the different processes (i.e., data collection, integration, filtering, anonymization and enrichment, and knowledge extraction) the study demonstrate their implementation using an open-source application able to access the DICOM metadata independently of the medical imaging modalities and equipment manufacturers.publishe

On the minimum hop count and connectivity in one-dimensional ad hoc wireless networks

This paper investigates connectivity in one-dimensional ad hoc networks by means of the distribution of the minimum hop count between source and destination nodes. We derive the exact probability distribution of the minimum hop count from the location density of relay nodes in the multihop path selected with the Most Forward within Radius (MFR) scheme. The probability that the source and destination nodes are connected (provided by Ghasemi and Nader-Esfahani [IEEE Commun. Lett. 10(4):251–253, 2006]) can be obtained by summing the probability masses for each possible value of the minimum hop count, which provides new insights to the connectivity probability. Numerical results show the effect of the number of nodes and the transmission range on the minimum hop count

Probing a M/G/1 queue with general input and service times

We consider the estimation of the arrival rate and the service time moments of a M/G/1 queue with probing, i.e., with special customers (probes) entering the system. The probe inter-arrival times are i.i.d. and probe service times follow a general positive distribution. The only observations used are the arrival times, service times and departure times of probes. We derive the main equations from which the quantities of interest can be estimated. Two particular probe arrivals, deterministic and Poisson, are investigated

Probing a M/G/1 queue with general input and service times

We consider the estimation of the arrival rate and the service time moments of a $M/G/1$ queue with probing, i.e., with special customers (probes) entering the system. The probe inter-arrival times are i.i.d. and probe service times follow a general positive distribution. The only observations used are the arrival times, service times and departure times of probes. We derive the main equations from which the quantities of interest can be estimated. Two particular probe arrivals, deterministic and Poisson, are investigated

Castro Lusitano Virtual: Software Livre e Património Virtual

O presente texto apresenta os objetivos e atual estado de desenvolvimento do projeto Castro Lusitano Virtual, um ambiente tridimensional interativo representativo de um povoado da Idade do Ferro da região Centro de Portugal, juntamente com a descrição de alguns conceitos que constituem o respetivo enquadramento e fundamentos do projeto. A Arqueologia e o Património Virtual são convocados nesse sentido, assim como a ecologia de conceitos e práticas em torno do Software Livre, incluindo cultura livre. O Castro Lusitano Virtual pode ser considerado como um recurso educacional aberto (Open Educational Resource), discutindo-se ideias sobre a sua utilização, nomeadamente distinguindo o aluno como explorador e como criador de ambiente tridimensionais. A utilização do projeto é focada, neste artigo, no contexto escolar, nomeadamente no ensino da História