358 research outputs found
Performance assessment of mobility solutions for IPv6-based healthcare wireless sensor networks
This thesis focuses on the study of mobile wireless sensor networks applied to healthcare
scenarios. The promotion of better quality-of-life for hospitalized patients is addressed in this
research work with a solution that can help these patients to keep their mobility (if possible).
The solution proposed allows remote monitoring and control of patients’ health in real-time
and without interruptions. Small sensor nodes able to collect and send wirelessly the health
parameters allow for the control of the patients' health condition. A network infrastructure,
composed by several access points, allows the connection of the sensor nodes (carried by the
patients) to remote healthcare providers. To ensure continuous access to sensor nodes special
attention should be dedicated to manage the transition of these sensor nodes between
different access points’ coverage areas. The process of changing an access point attachment
of a sensor node is called handover. In that context, this thesis proposes a new handover
mechanism that can ensure continuous connection to mobile sensor nodes in a healthcare
wireless sensor network. Due to the limitations of sensor nodes’ resources, namely available
energy (these sensor nodes are typically powered by small batteries), the proposed
mechanism pays a special attention in the optimization of energy consumption. To achieve
this optimization, part of this work is dedicated to the construction of a small sensor node.
The handover mechanism proposed in this work is called Hand4MAC (handover mechanism for
MAC layer). This mechanism is compared with other mechanisms commonly used in handover
management. The Hand4MAC mechanism is deployed and validated through by simulation and
in a real testbed. The scenarios used for the validation reproduces a hospital ward. The
performance evaluation is focused in the percentage of time that senor nodes are accessible
to the network while traveling across several access points’ coverage areas and the energy
expenditures in handover processes. The experiments performed take into account various
parameters that are the following: number of sent messages, number of received messages,
multicast message usage, energy consumption, number of sensor nodes present in the
scenario, velocity of sensor nodes, and time-to-live value. In both simulation and real
testbed, the Hand4MAC mechanism is shown to perform better than all the other handover
mechanisms tested. In this comparison it was only considered the most promising handover
mechanisms proposed in the literature.Fundação para a Ciência e a Tecnologia (FCT
Building the Future Internet through FIRE
The Internet as we know it today is the result of a continuous activity for improving network communications, end user services, computational processes and also information technology infrastructures. The Internet has become a critical infrastructure for the human-being by offering complex networking services and end-user applications that all together have transformed all aspects, mainly economical, of our lives. Recently, with the advent of new paradigms and the progress in wireless technology, sensor networks and information systems and also the inexorable shift towards everything connected paradigm, first as known as the Internet of Things and lately envisioning into the Internet of Everything, a data-driven society has been created. In a data-driven society, productivity, knowledge, and experience are dependent on increasingly open, dynamic, interdependent and complex Internet services. The challenge for the Internet of the Future design is to build robust enabling technologies, implement and deploy adaptive systems, to create business opportunities considering increasing uncertainties and emergent systemic behaviors where humans and machines seamlessly cooperate
Air Force Institute of Technology Research Report 2007
This report summarizes the research activities of the Air Force Institute of Technology’s Graduate School of Engineering and Management. It describes research interests and faculty expertise; lists student theses/dissertations; identifies research sponsors and contributions; and outlines the procedures for contacting the school. Included in the report are: faculty publications, conference presentations, consultations, and funded research projects. Research was conducted in the areas of Aeronautical and Astronautical Engineering, Electrical Engineering and Electro-Optics, Computer Engineering and Computer Science, Systems and Engineering Management, Operational Sciences, Mathematics, Statistics and Engineering Physics
Building the Future Internet through FIRE
The Internet as we know it today is the result of a continuous activity for improving network communications, end user services, computational processes and also information technology infrastructures. The Internet has become a critical infrastructure for the human-being by offering complex networking services and end-user applications that all together have transformed all aspects, mainly economical, of our lives. Recently, with the advent of new paradigms and the progress in wireless technology, sensor networks and information systems and also the inexorable shift towards everything connected paradigm, first as known as the Internet of Things and lately envisioning into the Internet of Everything, a data-driven society has been created. In a data-driven society, productivity, knowledge, and experience are dependent on increasingly open, dynamic, interdependent and complex Internet services. The challenge for the Internet of the Future design is to build robust enabling technologies, implement and deploy adaptive systems, to create business opportunities considering increasing uncertainties and emergent systemic behaviors where humans and machines seamlessly cooperate
Enhancing trustability in MMOGs environments
Massively Multiplayer Online Games (MMOGs; e.g., World of Warcraft), virtual worlds
(VW; e.g., Second Life), social networks (e.g., Facebook) strongly demand for more
autonomic, security, and trust mechanisms in a way similar to humans do in the real
life world. As known, this is a difficult matter because trusting in humans and organizations
depends on the perception and experience of each individual, which is difficult to
quantify or measure. In fact, these societal environments lack trust mechanisms similar
to those involved in humans-to-human interactions. Besides, interactions mediated
by compute devices are constantly evolving, requiring trust mechanisms that keep the
pace with the developments and assess risk situations.
In VW/MMOGs, it is widely recognized that users develop trust relationships from their
in-world interactions with others. However, these trust relationships end up not being
represented in the data structures (or databases) of such virtual worlds, though they
sometimes appear associated to reputation and recommendation systems. In addition,
as far as we know, the user is not provided with a personal trust tool to sustain his/her
decision making while he/she interacts with other users in the virtual or game world.
In order to solve this problem, as well as those mentioned above, we propose herein a
formal representation of these personal trust relationships, which are based on avataravatar
interactions. The leading idea is to provide each avatar-impersonated player
with a personal trust tool that follows a distributed trust model, i.e., the trust data is
distributed over the societal network of a given VW/MMOG.
Representing, manipulating, and inferring trust from the user/player point of view certainly
is a grand challenge. When someone meets an unknown individual, the question
is “Can I trust him/her or not?”. It is clear that this requires the user to have access to
a representation of trust about others, but, unless we are using an open source VW/MMOG,
it is difficult —not to say unfeasible— to get access to such data. Even, in an open
source system, a number of users may refuse to pass information about its friends, acquaintances,
or others. Putting together its own data and gathered data obtained from
others, the avatar-impersonated player should be able to come across a trust result
about its current trustee. For the trust assessment method used in this thesis, we use
subjective logic operators and graph search algorithms to undertake such trust inference
about the trustee. The proposed trust inference system has been validated using
a number of OpenSimulator (opensimulator.org) scenarios, which showed an accuracy
increase in evaluating trustability of avatars.
Summing up, our proposal aims thus to introduce a trust theory for virtual worlds, its
trust assessment metrics (e.g., subjective logic) and trust discovery methods (e.g.,
graph search methods), on an individual basis, rather than based on usual centralized
reputation systems. In particular, and unlike other trust discovery methods, our methods
run at interactive rates.MMOGs (Massively Multiplayer Online Games, como por exemplo, World of Warcraft),
mundos virtuais (VW, como por exemplo, o Second Life) e redes sociais (como por exemplo,
Facebook) necessitam de mecanismos de confiança mais autónomos, capazes de
assegurar a segurança e a confiança de uma forma semelhante à que os seres humanos
utilizam na vida real. Como se sabe, esta não é uma questão fácil. Porque confiar em
seres humanos e ou organizações depende da percepção e da experiĂŞncia de cada indivĂduo,
o que Ă© difĂcil de quantificar ou medir Ă partida. Na verdade, esses ambientes
sociais carecem dos mecanismos de confiança presentes em interacções humanas presenciais.
Além disso, as interacções mediadas por dispositivos computacionais estão em
constante evolução, necessitando de mecanismos de confiança adequados ao ritmo da
evolução para avaliar situações de risco.
Em VW/MMOGs, é amplamente reconhecido que os utilizadores desenvolvem relações
de confiança a partir das suas interacções no mundo com outros. No entanto, essas relações
de confiança acabam por não ser representadas nas estruturas de dados (ou bases
de dados) do VW/MMOG especĂfico, embora Ă s vezes apareçam associados Ă reputação
e a sistemas de reputação. Além disso, tanto quanto sabemos, ao utilizador não lhe
é facultado nenhum mecanismo que suporte uma ferramenta de confiança individual
para sustentar o seu processo de tomada de decisĂŁo, enquanto ele interage com outros
utilizadores no mundo virtual ou jogo. A fim de resolver este problema, bem como
os mencionados acima, propomos nesta tese uma representação formal para essas relações
de confiança pessoal, baseada em interacções avatar-avatar. A ideia principal
é fornecer a cada jogador representado por um avatar uma ferramenta de confiança
pessoal que segue um modelo de confiança distribuĂda, ou seja, os dados de confiança
sĂŁo distribuĂdos atravĂ©s da rede social de um determinado VW/MMOG.
Representar, manipular e inferir a confiança do ponto de utilizador/jogador, é certamente
um grande desafio. Quando alguĂ©m encontra um indivĂduo desconhecido, a
pergunta é “Posso confiar ou não nele?”. É claro que isto requer que o utilizador tenha
acesso a uma representação de confiança sobre os outros, mas, a menos que possamos
usar uma plataforma VW/MMOG de cĂłdigo aberto, Ă© difĂcil — para nĂŁo dizer impossĂvel
— obter acesso aos dados gerados pelos utilizadores. Mesmo em sistemas de código
aberto, um número de utilizadores pode recusar partilhar informações sobre seus amigos,
conhecidos, ou sobre outros. Ao juntar seus prĂłprios dados com os dados obtidos de
outros, o utilizador/jogador representado por um avatar deve ser capaz de produzir uma
avaliação de confiança sobre o utilizador/jogador com o qual se encontra a interagir.
Relativamente ao método de avaliação de confiança empregue nesta tese, utilizamos
lógica subjectiva para a representação da confiança, e também operadores lógicos da
lĂłgica subjectiva juntamente com algoritmos de procura em grafos para empreender
o processo de inferência da confiança relativamente a outro utilizador. O sistema de
inferência de confiança proposto foi validado através de um número de cenários Open-Simulator (opensimulator.org), que mostrou um aumento na precisão na avaliação da
confiança de avatares.
Resumindo, a nossa proposta visa, assim, introduzir uma teoria de confiança para mundos
virtuais, conjuntamente com métricas de avaliação de confiança (por exemplo, a
lógica subjectiva) e em métodos de procura de caminhos de confiança (com por exemplo,
através de métodos de pesquisa em grafos), partindo de uma base individual, em
vez de se basear em sistemas habituais de reputação centralizados. Em particular, e ao
contrário de outros métodos de determinação do grau de confiança, os nossos métodos
sĂŁo executados em tempo real
Improving the Performance of Wireless LANs
This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids
Turku Centre for Computer Science – Annual Report 2013
Due to a major reform of organization and responsibilities of TUCS, its role, activities, and even structures have been under reconsideration in 2013. The traditional pillar of collaboration at TUCS, doctoral training, was reorganized due to changes at both universities according to the renewed national system for doctoral education. Computer Science and Engineering and Information Systems Science are now accompanied by Mathematics and Statistics in newly established doctoral programs at both University of Turku and Åbo Akademi University. Moreover, both universities granted sufficient resources to their respective programmes for doctoral training in these fields, so that joint activities at TUCS can continue. The outcome of this reorganization has the potential of proving out to be a success in terms of scientific profile as well as the quality and quantity of scientific and educational results.
International activities that have been characteristic to TUCS since its inception continue strong. TUCS’ participation in European collaboration through EIT ICT Labs Master’s and Doctoral School is now more active than ever. The new double degree programs at MSc and PhD level between University of Turku and Fudan University in Shaghai, P.R.China were succesfully set up and are
now running for their first year. The joint students will add to the already international athmosphere of the ICT House.
The four new thematic reseach programmes set up acccording to the decision by the TUCS Board have now established themselves, and a number of events and other activities saw the light in 2013. The TUCS Distinguished Lecture Series managed to gather a large audience with its several prominent speakers. The development of these and other research centre activities continue, and
new practices and structures will be initiated to support the tradition of close academic collaboration.
The TUCS’ slogan Where Academic Tradition Meets the Exciting Future has proven true throughout these changes. Despite of the dark clouds on the national and European economic sky, science and higher education in the field have managed to retain all the key ingredients for success. Indeed, the future of ICT and Mathematics in Turku seems exciting.</p
Communities at a Crossroads. Material semiotics for online sociability in the fade of cyberculture
How to conceptualize online sociability in the 21st century? To answer this question, Communities at a Crossroads looks back at the mid-2000s. With the burst of the creative-entrepreneur alliance, the territorialization of the internet and the commercialization of interpersonal ties, that period constituted a turning point for digital communitarian cultures. Many of the techno-libertarian culture\u2019s utopias underpinning the ideas for online sociability faced systematic counter evidence. This change in paradigm has still consequences today.
Avoiding both empty invocations of community and swift conclusions of doom, Annalisa Pelizza investigates the theories of actions that have underpinned the development of techno-social digital assemblages after the \u2018golden age\u2019 of online communities. Communities at a Crossroads draws upon the analysis of Ars Electronica\u2019s Digital Communities archive, which is the largest of its kind worldwide, and in doing so presents a multi-faceted picture of internet sociability between the two centuries.
Privileging an anti-essentialist, performative approach over sociological understandings of online communities, Communities at a Crossroads proposes a radical epistemological turn. It argues that in order to conceptualize contemporary online sociability, we need first to abandon the techno-libertarian communalist rhetoric. Then, it is necessary to move beyond the foundational distinction between Gemeinschaft and Gesellschaft, and adopt a material semiotic approach. In the end, we might have to relinquish the effort to define online or digital communities and engage in more meaningful mapping exercises
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