Response time analysis of slotted WiDom in noisy wireless channels

WiDom is a wireless prioritized medium access control protocol which offers very large number of priority levels. Hence, it brings the potential to employ non-preemptive static-priority scheduling and schedulability analysis for a wireless channel assuming that the overhead of WiDom is modeled properly. Recent research has created a new version of WiDom (we call it: Slotted WiDom) which offers lower overhead compared to the previous version. In this paper we propose a new schedulability analysis for slotted WiDom and extend it to work for message streams with release jitter. Furthermore, to provide an accurate timing analysis, we must include the effect of transmission faults on message latencies. Thus, in the proposed analysis we consider the existence of different noise sources and develop the analysis for the case where messages are transmitted under noisy wireless channels. Evaluation of the proposed analysis is done by testing the slotted WiDom in two different modes on a real test-bed. The results from the experiments provide a firm validation on our findings.

Soil erosion after forest fires: evaluation of mitigation measures applied to drainage channels in the northwest of Portugal

The development and implementation of measures which promote the reduction of the impacts of forest fires on soils is imperative and should be part of any strategy for forest and soil preservation and recovery, especially considering the actual scenario of continuous growth in the number of fires and burnt area. Consequently, with the dendrocaustologic reality that has characterized the Portuguese mainland in recent decades, a research project promoted by the Center for the Study of Geography and Spatial Planning (CEGOT) was implemented with the objective of applying several erosion mitigation measures in a burned area of the Peneda-Geres National Park in NW Portugal. This paper therefore seeks to present the measures applied in the study area within the project Soil Protec, relating to triggered channel processes and the results of preliminary observations concerning the evaluation of the effectiveness of erosion mitigation measures implemented, as well as their cost/benefit ratio.

Characterisation of noisy speech channels in 2G and 3G mobile networks

As the wireless cellular market reaches competitive levels never seen before, network operators need to focus on maintaining Quality of Service (QoS) a main priority if they wish to attract new subscribers while keeping existing customers satisfied. Speech Quality as perceived by the end user is one major example of a characteristic in constant need of maintenance and improvement. It is in this topic that this Master Thesis project fits in. Making use of an intrusive method of speech quality evaluation, as a means to further study and characterize the performance of speech codecs in second-generation (2G) and third-generation (3G) technologies. Trying to find further correlation between codecs with similar bit rates, along with the exploration of certain transmission parameters which may aid in the assessment of speech quality. Due to some limitations concerning the audio analyzer equipment that was to be employed, a different system for recording the test samples was sought out. Although the new designed system is not standard, after extensive testing and optimization of the system's parameters, final results were found reliable and satisfactory. Tests include a set of high and low bit rate codecs for both 2G and 3G, where values were compared and analysed, leading to the outcome that 3G speech codecs perform better, under the approximately same conditions, when compared with 2G. Reinforcing the idea that 3G is, with no doubt, the best choice if the costumer looks for the best possible listening speech quality. Regarding the transmission parameters chosen for the experiment, the Receiver Quality (RxQual) and Received Energy per Chip to the Power Density Ratio (Ec/N0), these were subject to speech quality correlation tests. Final results of RxQual were compared to those of prior studies from different researchers and, are considered to be of important relevance. Leading to the confirmation of RxQual as a reliable indicator of speech quality. As for Ec/N0, it is not possible to state it as a speech quality indicator however, it shows clear thresholds for which the MOS values decrease significantly. The studied transmission parameters show that they can be used not only for network management purposes but, at the same time, give an expected idea to the communications engineer (or technician) of the end-to-end speech quality consequences. With the conclusion of the work new ideas for future studies come to mind. Considering that the fourth-generation (4G) cellular technologies are now beginning to take an important place in the global market, as the first all-IP network structure, it seems of great relevance that 4G speech quality should be subject of evaluation. Comparing it to 3G, not only in narrowband but also adding wideband scenarios with the most recent standard objective method of speech quality assessment, POLQA. Also, new data found on Ec/N0 tests, justifies further research studies with the intention of validating the assumptions made in this work.

Response Time Analysis of Slotted WiDOM in Noisy Wireless Channels

International Conference on Emerging Technologies and Factory Automation (ETFA 2015), Industrial Communication Technologies and Systems, Luxembourg, Luxembourg.

Performance Model for MRC Receivers with Adaptive Modulation and Coding in Rayleigh Fading Correlated Channels with Imperfect CSIT

RTUWO Advances in Wireless and Optical Communications 2015 (RTUWO 2015). 5-6 Nov Riga, Latvia.

Cation transporters/channels in plants: Tools for nutrient biofortification

Cation transporters/channels are key players in a wide range of physiological functions in plants, including cell signaling, osmoregulation, plant nutrition and metal tolerance. The recent identification of genes encoding some of these transport systems has allowed new studies toward further understanding of their integrated roles in plant. This review summarizes recent discoveries regarding the function and regulation of the multiple systems involved in cation transport in plant cells. The role of membrane transport in the uptake, distribution and accumulation of cations in plant tissues, cell types and subcellular compartments is described. We also discuss how the knowledge of inter- and intra-species variation in cation uptake, transport and accumulation as well as the molecular mechanisms responsible for these processes can be used to increase nutrient phytoavailability and nutrients accumulation in the edible tissues of plants. The main trends for future research in the field of biofortification are proposed.

All the world in a boat: portuguese folklore, common sense and ideology

This essay sees ���through��� an object produced by Portuguese folklore: the moliceiro boat of Ria de Aveiro, whose most original characteristic is the group of four different panels painted on each boat. These unique panels have echoed national mythologies and have undergone influence from institutional channels of instruction and propaganda for much of the twentieth century. We will analyse how this boat expresses the inventory of a community���s identity, imagination, and practices.

Sistema de recomenda����o e personaliza����o de televis��o

Com a expans��o da Televis��o Digital e a converg��ncia entre os meios de difus��o convencionais e a televis��o sobre IP, o n��mero de canais dispon��veis tem aumentado de forma gradual colocando o espectador numa situa����o de dif��cil escolha quanto ao programa a visionar. Sobrecarregados com uma grande quantidade de programas e informa����o associada, muitos espectadores desistem sistematicamente de ver um programa e tendem a efectuar zapping entre diversos canais ou a assistir sempre aos mesmos programas ou canais. Diante deste problema de sobrecarga de informa����o, os sistemas de recomenda����o apresentam-se como uma solu����o. Nesta tese pretende estudar-se algumas das solu����es existentes dos sistemas de recomenda����o de televis��o e desenvolver uma aplica����o que permita a recomenda����o de um conjunto de programas que representem potencial interesse ao espectador. S��o abordados os principais conceitos da ��rea dos algoritmos de recomenda����o e apresentados alguns dos sistemas de recomenda����o de programas de televis��o desenvolvidos at�� �� data. Para realizar as recomenda����es foram desenvolvidos dois algoritmos baseados respectivamente em t��cnicas de filtragem colaborativa e de filtragem de conte��do. Estes algoritmos permitem atrav��s do c��lculo da similaridade entre itens ou utilizadores realizar a predi����o da classifica����o que um utilizador atribuiria a um determinado item (programa de televis��o, filme, etc.). Desta forma �� poss��vel avaliar o n��vel de potencial interesse que o utilizador ter�� em rela����o ao respectivo item. Os conjuntos de dados que descrevem as caracter��sticas dos programas (t��tulo, g��nero, actores, etc.) s��o armazenados de acordo com a norma TV-Anytime. Esta norma de descri����o de conte��do multim��dia apresenta a vantagem de ser especificamente vocacionada para conte��do audiovisual e est�� dispon��vel livremente. O conjunto de recomenda����es obtidas �� apresentado ao utilizador atrav��s da interac����o com uma aplica����o Web que permite a integra����o de todos os componentes do sistema. Para valida����o do trabalho foi considerado um dataset de teste designado de htrec2011-movielens-2k e cujo conte��do corresponde a um conjunto de filmes classificados por diversos utilizadores num ambiente real. Este conjunto de filmes possui, para al��m da classifica����es atribu��das pelos utilizadores, um conjunto de dados que descrevem o g��nero, directores, realizadores e pa��s de origem. Para valida����o final do trabalho foram realizados diversos testes dos quais o mais relevante correspondeu �� avalia����o da dist��ncia entre predi����es e valores reais e cujo objectivo �� classificar a capacidade dos algoritmos desenvolvidos preverem com precis��o as classifica����es que os utilizadores atribuiriam aos itens analisados.

Levantamento, repara����o e beneficia����o do simulador TERCO PST 2200 do Laborat��rio de Sistemas de Energia do ISEP

Este trabalho �� baseado no simulador de redes PST2200 do Laborat��rio de Sistemas de Energia (LSE) pois est�� avariado com v��rios problemas conhecidos, designadamente: - Defeito de isolamento (disparo de diferencial), - Desregula����o da velocidade da m��quina prim��ria (motor DC), - Circuito de excita����o da m��quina s��ncrona inoperacional, - Inexist��ncia de esquemas el��tricos dos circuitos do simulador, - Medidas desreguladas e com canais de medida com circuito impresso queimado. O trabalho executado foi: - O levantamento e desenho de raiz (n��o existe qualquer manual) dos esquemas dos 10 m��dulos do simulador, designadamente naqueles com avaria ou com desempenho problem��tico a fim de que se possa ter uma vis��o mais pormenorizada dos circuitos e seus problemas, por forma a intervir para os minimizar e resolver, - Foi realizado o diagn��stico de avaria do simulador e foram propostas solu����es para os mesmos, - Realizaram-se as interven����es propostas e aprovadas. Nas interven����es realizadas, os princ��pios orientadores foram: - Aumentar a robustez do equipamento por forma a garantir a sua integridade a utiliza����es menos apropriados e manobras 'ex��ticas' pr��prias de alunos, que pela sua condi����o, est��o em fase de aprendizagem, - Atualizar o equipamento, colocando-o em sintonia com o 'estado da arte', - Como fator de valoriza����o suplementar, foi concebida e aplicada a supervis��o remota do funcionamento do simulador atrav��s da rede inform��tica. Foram detetados in��meros erros: - M�� liga����o do motor de corrente continua ao variador, resultando a falta de controlo da frequ��ncia da rede do sistema, - Liga����es entre pain��is trocadas resultando em avarias diversas das fontes de alimenta����o, - Cartas eletr��nicas de medidas avariadas e que al��m de se reparar, foram tamb��m calibradas. Devido ao mecenato da empresa Schnitt + Sohn participando monetariamente, fez-se o projeto de altera����o e respetiva execu����o de grande parte do simulador aumentando a fiabilidade do mesmo, diminuindo assim a frequ��ncia das avarias naturais mais as que acontecem involuntariamente devido a este ser um instrumento did��tico. Al��m do trabalho el��trico, foi feito muito trabalho de chaparia para altera����o de estrutura e suporte do material com diferen��as de posicionamento. Neste trabalho d��-se tamb��m alguns exemplos de c��lculo e simula����o das redes de transporte que se pode efetuar no simulador como estudo e simula����o de avarias num sistema produtivo real. Realizou-se a monitoriza����o de dois aparelhos indicadores de par��metros de energia (Janitza UMG96S) atrav��s duma rede com dois protocolos ethernet e profibus utilizando o plc (Omron CJ2M) como valoriza����o do trabalho.