304 research outputs found
Communication between nodes for autonomic and distributed management
Doutoramento conjunto MAPi em InformáticaOver the last decade, the most widespread approaches for traditional management
were based on the Simple Network Management Protocol (SNMP) or Common
Management Information Protocol (CMIP). However, they both have several problems
in terms of scalability, due to their centralization characteristics. Although
the distributed management approaches exhibit better performance in terms of
scalability, they still underperform regarding communication costs, autonomy, extensibility,
exibility, robustness, and cooperation between network nodes. The
cooperation between network nodes normally requires excessive overheads for synchronization
and dissemination of management information in the network. For
emerging dynamic and large-scale networking environments, as envisioned in Next
Generation Networks (NGNs), exponential growth in the number of network devices
and mobile communications and application demands is expected. Thus, a
high degree of management automation is an important requirement, along with
new mechanisms that promote it optimally and e ciently, taking into account the
need for high cooperation between the nodes. Current approaches for self and autonomic
management allow the network administrator to manage large areas, performing
fast reaction and e ciently facing unexpected problems. The management
functionalities should be delegated to a self-organized plane operating within the
network, that decrease the network complexity and the control information ow,
as opposed to centralized or external servers. This Thesis aims to propose and
develop a communication framework for distributed network management which
integrates a set of mechanisms for initial communication, exchange of management
information, network (re) organization and data dissemination, attempting
to meet the autonomic and distributed management requirements posed by NGNs.
The mechanisms are lightweight and portable, and they can operate in di erent
hardware architectures and include all the requirements to maintain the basis for
an e cient communication between nodes in order to ensure autonomic network
management. Moreover, those mechanisms were explored in diverse network conditions
and events, such as device and link errors, di erent tra c/network loads
and requirements. The results obtained through simulation and real experimentation
show that the proposed mechanisms provide a lower convergence time, smaller
overhead impact in the network, faster dissemination of management information,
increase stability and quality of the nodes associations, and enable the support for
e cient data information delivery in comparison to the base mechanisms analyzed.
Finally, all mechanisms for communication between nodes proposed in this Thesis,
that support and distribute the management information and network control
functionalities, were devised and developed to operate in completely decentralized
scenarios.Durante a última década, protocolos como Simple Network Management Protocol
(SNMP) ou Common Management Information Protocol (CMIP) foram as abordagens
mais comuns para a gestão tradicional de redes. Essas abordagens têm
vários problemas em termos de escalabilidade, devido às suas características de
centralização. Apresentando um melhor desempenho em termos de escalabilidade,
as abordagens de gestão distribuída, por sua vez, são vantajosas nesse sentido,
mas também apresentam uma série de desvantagens acerca do custo elevado de
comunicação, autonomia, extensibilidade, exibilidade, robustez e cooperação entre
os nós da rede. A cooperação entre os nós presentes na rede é normalmente
a principal causa de sobrecarga na rede, uma vez que necessita de colectar, sincronizar
e disseminar as informações de gestão para todos os nós nela presentes.
Em ambientes dinâmicos, como é o caso das redes atuais e futuras, espera-se um
crescimento exponencial no número de dispositivos, associado a um grau elevado
de mobilidade dos mesmos na rede. Assim, o grau elevado de funções de automatiza
ção da gestão da rede é uma exigência primordial, bem como o desenvolvimento
de novos mecanismos e técnicas que permitam essa comunicação de forma optimizada
e e ciente. Tendo em conta a necessidade de elevada cooperação entre
os elementos da rede, as abordagens atuais para a gestão autonómica permitem
que o administrador possa gerir grandes áreas de forma rápida e e ciente frente
a problemas inesperados, visando diminuir a complexidade da rede e o uxo de
informações de controlo nela gerados. Nas gestões autonómicas a delegação de
operações da rede é suportada por um plano auto-organizado e não dependente
de servidores centralizados ou externos. Com base nos tipos de gestão e desa os
acima apresentados, esta Tese tem como principal objetivo propor e desenvolver
um conjunto de mecanismos necessários para a criação de uma infra-estrutura
de comunicação entre nós, na tentativa de satisfazer as exigências da gestão auton
ómica e distribuída apresentadas pelas redes de futura geração. Nesse sentido,
mecanismos especí cos incluindo inicialização e descoberta dos elementos da rede,
troca de informação de gestão, (re) organização da rede e disseminação de dados
foram elaborados e explorados em diversas condições e eventos, tais como: falhas
de ligação, diferentes cargas de tráfego e exigências de rede. Para além disso, os
mecanismos desenvolvidos são leves e portáveis, ou seja, podem operar em diferentes
arquitecturas de hardware e contemplam todos os requisitos necessários para
manter a base de comunicação e ciente entre os elementos da rede. Os resultados
obtidos através de simulações e experiências reais comprovam que os mecanismos
propostos apresentam um tempo de convergência menor para descoberta e troca
de informação, um menor impacto na sobrecarga da rede, disseminação mais rápida
da informação de gestão, aumento da estabilidade e a qualidade das ligações entre
os nós e entrega e ciente de informações de dados em comparação com os mecanismos
base analisados. Finalmente, todos os mecanismos desenvolvidos que fazem
parte da infrastrutura de comunicação proposta foram concebidos e desenvolvidos
para operar em cenários completamente descentralizados
Proceedings of the SAB'06 Workshop on Adaptive Approaches for Optimizing Player Satisfaction in Computer and Physical Games
These proceedings contain the papers presented at the Workshop on Adaptive approaches
for Optimizing Player Satisfaction in Computer and Physical Games held at the Ninth
international conference on the Simulation of Adaptive Behavior (SAB’06): From
Animals to Animats 9 in Rome, Italy on 1 October 2006.
We were motivated by the current state-of-the-art in intelligent game design using
adaptive approaches. Artificial Intelligence (AI) techniques are mainly focused on
generating human-like and intelligent character behaviors. Meanwhile there is generally
little further analysis of whether these behaviors contribute to the satisfaction of the
player. The implicit hypothesis motivating this research is that intelligent opponent
behaviors enable the player to gain more satisfaction from the game. This hypothesis may
well be true; however, since no notion of entertainment or enjoyment is explicitly
defined, there is therefore little evidence that a specific character behavior generates
enjoyable games.
Our objective for holding this workshop was to encourage the study, development,
integration, and evaluation of adaptive methodologies based on richer forms of humanmachine
interaction for augmenting gameplay experiences for the player. We wanted to
encourage a dialogue among researchers in AI, human-computer interaction and
psychology disciplines who investigate dissimilar methodologies for improving gameplay
experiences. We expected that this workshop would yield an understanding of state-ofthe-
art approaches for capturing and augmenting player satisfaction in interactive systems
such as computer games.
Our invited speaker was Hakon Steinø, Technical Producer of IO-Interactive, who
discussed applied AI research at IO-Interactive, portrayed the future trends of AI in
computer game industry and debated the use of academic-oriented methodologies for
augmenting player satisfaction. The sessions of presentations and discussions where
classified into three themes: Adaptive Learning, Examples of Adaptive Games and Player
Modeling.
The Workshop Committee did a great job in providing suggestions and informative
reviews for the submissions; thank you! This workshop was in part supported by the
Danish National Research Council (project no: 274-05-0511). Finally, thanks to all the
participants; we hope you found this to be useful!peer-reviewe
Legged locomotion over irregular terrains: State of the art of human and robot performance
Legged robotic technologies have moved out of the lab to operate in real environments, characterized by a wide variety of unpredictable irregularities and disturbances, all this in close proximity with humans. Demonstrating the ability of current robots to move robustly and reliably in these conditions is becoming essential to prove their safe operation. Here, we report an in-depth literature review aimed at verifying the existence of common or agreed protocols and metrics to test the performance of legged system in realistic environments. We primarily focused on three types of robotic technologies, i.e., hexapods, quadrupeds and bipeds. We also included a comprehensive overview on human locomotion studies, being it often considered the gold standard for performance, and one of the most important sources of bioinspiration for legged machines. We discovered that very few papers have rigorously studied robotic locomotion under irregular terrain conditions. On the contrary, numerous studies have addressed this problem on human gait, being nonetheless of highly heterogeneous nature in terms of experimental design. This lack of agreed methodology makes it challenging for the community to properly assess, compare and predict the performance of existing legged systems in real environments. On the one hand, this work provides a library of methods, metrics and experimental protocols, with a critical analysis on the limitations of the current approaches and future promising directions. On the other hand, it demonstrates the existence of an important lack of benchmarks in the literature, and the possibility of bridging different disciplines, e.g., the human and robotic, towards the definition of standardized procedure that will boost not only the scientific development of better bioinspired solutions, but also their market uptake
Coordinated multi-robot formation control
Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201
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A Novel Multi-View Table Tennis Umpiring Framework
This research investigates the development of a low-cost multi-view umpiring framework, as an alternative to the current expensive systems that are almost exclusively restricted to elite professional sports. Table tennis has been selected as the testbed because, while automating the process is challenging, it has many different complex match elements including the service, return and rallies, which are governed by a strict set of regulations. The focus is mainly on the rally element rather than the whole match. Ball detection and tracking in video frames are undertaken to determine reliably the ball position relative to key reference objects like the table surface and net, and the ball’s flight path is used to determine the rally’s status.
While a low-cost option has benefits, it is technically challenging due to the limited number of cameras and generally low video resolution used. This thesis presents a portable multi-view umpiring framework that identifies each state change in a rally. It makes three significant contributions to knowledge: i) a reliable ball detection strategy that accurately detects the location of the ball in low-resolution sequences; ii) a novel framework for ball tracking using a multi-view system, and iii) a new state-machine based evaluation system for analysing table tennis rallies.
In a series of ten different test scenarios, the system achieved an average of 94% system detection rate and 100% accurate decisions. A test sequence of duration 1 s can be processed in 8 s, leading to a delay of only 7 s, which is considered acceptable for practical purposes. This solution has the potential to reform the way matches are umpired, providing objectivity in resolving disputed decisions. It affords an economic technology for amateur players, while the multi-view facility is extendible to other relevant ball-based sports. Finally, the ball flight path analysis mechanism can be a valuable training tool for skills development
A Multi-Agent Energy Trading Competition
The energy sector will undergo fundamental changes over the next ten years. Prices for fossil energy resources are continuously increasing, there is an urgent need to reduce CO2 emissions, and the United States and European Union are strongly motivated to become more independent from foreign energy imports. These factors will lead to installation of large numbers of distributed renewable energy generators, which are often intermittent in nature. This trend conflicts with the current power grid control infrastructure and strategies, where a few centralized control centers manage a limited number of large power plants such that their output meets the energy demands in real time. As the proportion of distributed and intermittent generation capacity increases, this task becomes much harder, especially as the local and regional distribution grids where renewable energy generators are usually installed are currently virtually unmanaged, lack real time metering and are not built to cope with power flow inversions (yet).
All this is about to change, and so the control strategies must be adapted accordingly. While the hierarchical command-and-control approach served well in a world with a few large scale generation facilities and many small consumers, a more flexible, decentralized, and self-organizing control infrastructure will have to be developed that can be actively managed to balance both the large grid as a whole, as well as the many lower voltage sub-grids.
We propose a competitive simulation test bed to stimulate research and development of electronic agents that help manage these tasks. Participants in the competition will develop intelligent agents that are responsible to level energy supply from generators with energy demand from consumers. The competition is designed to closely model reality by bootstrapping the simulation environment with real historic load, generation, and weather data. The simulation environment will provide a low-risk platform that combines simulated markets and real-world data to develop solutions that can be applied to help building the self-organizing intelligent energy grid of the future
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