<p>Through the desire of understanding the Internet better, we focused our attention on the modelling of the way data move in the Internet. Our main goal here was to give ideas on what does a route followed by packets look like. </p><p>In most of the simulations, researchers model routes by shortest paths, we try to provide more realistic models to improve simulations accuracy out of concern for keeping it relatively simple. </p><p>To achieve this study, we used the data from the Skitter network measurement platform that runs about thirty monitors which probe tens of thousands destinations per day around the world in order to collect routes packets have followed with the path forwarding method. It is the largest known effort of route collection and also a mean to get a realistic topology of the Internet. </p><p>With the help of the Skitter data we pointed out lots of global and local routes characteristics and we have designed some algorithms to generate fake routes that fit the properties observed.</p>

Through the desire of understanding the Internet better, we focused our attention on the modelling of the way data move in the Internet. Our main goal here was to give ideas on what does a route followed by packets look like. In most of the simulations, researchers model routes by shortest paths, we try to provide more realistic models to improve simulations accuracy out of concern for keeping it relatively simple. To achieve this study, we used the data from the Skitter network measurement platform that runs about thirty monitors which probe tens of thousands destinations per day around the world in order to collect routes packets have followed with the path forwarding method. It is the largest known effort of route collection and also a mean to get a realistic topology of the Internet. With the help of the Skitter data we pointed out lots of global and local routes characteristics and we have designed some algorithms to generate fake routes that fit the properties observed.

[pt] A robótica já é parte importante da vida cotidiana, em especial na grande ajuda que pode promover para melhorar a qualidade de vida, mostrando-se como uma ótima opção, por exemplo, para a reabilitação física no corpo humano. O presente trabalho apresenta um projeto e um estudo de controle de movimento de uma plataforma robótica - uma bengala - controlada por meio de sensores de força nela localizados, fazendo com que o registro dos movimentos do usuário seja feito de forma não-invasiva. O protótipo se desloca por meio de três rodas omnidirecionais, acionadas por motores elétricos de corrente continua. Estes últimos têm facilidade no controle e são de baixo custo. A bengala é fabricada em alumínio para facilitar o seu transporte devido à baixa densidade desse material, além de apresentar uma boa usinabilidade, facilitando a sua fabricação. O sistema eletrônico consiste de três etapas: (i) circuito de aquisição de ponte de Wheatstone para os extensômetros; (ii) amplificação e filtragem feitas com amplificadores de instrumentação e filtros passa baixa Butterworth; e (iii) processamento e controle, implementado em dois microcontroladores PIC. O controle da bengala é baseado em admitância em paralelo com um controle PI linear, o qual pretende promover ao usuário uma sensação de naturalidade ao caminhar, sem esforços adicionais significativos e com rápida resposta. Em particular, o sistema pretende detectar situações de queda iminente do usuário, cenário não incomum no uso por idosos. / [en] Robotics already is an important part of modern daily routine, with a quite unlimited potential for the improvement of life quality. For instance, robotics can be a very attractive technology for physical rehabilitation of the human body. The present work presents a design proposal and study of the stability control of an omnidirectional robotic walking cane for assistance of motor disabilities. Non-invasive force sensors are used to register the user s motions and to control the robotic cane. Three omnidirectional wheels, each of them driven by a continuous electrical current motor, move the prototype in all planar directions without the need for turning. The chosen electrical motors are characterized by their easy control and low cost. The stick is fabricated in aluminum, a low-density material with good machinability, in order to both facilitate the user in transporting the cane and to ease the manufacturing process. The electronic system is comprised of three stages: (i) a Wheatstone bridge circuit for the acquisition of strain-gage signals for force and torque sensing; (ii) amplification and filtering with instrumentation amplifiers and Butterworth-type low pass filters; and (iii) processing and control, implemented on two PIC microcontrollers. The control of the robotics support is performed both by an admittance-based approach in parallel with a linear PI control. The quick response of this integrated control does not demand extra efforts from the user, thus providing a more natural sensation while walking. In particular, the system intends to detect whether the user is in the imminence of falling over, a likely scenario in eldercare.