An ontology-based P2P infrastructure to support context discovery in pervasive computing

Master'sMASTER OF ENGINEERIN

Provision, discovery and development of ubiquitous services and applications

Ph.DDOCTOR OF PHILOSOPH

Raamistik mobiilsete asjade veebile

Internet on oma arengus läbi aastate jõudnud järgmisse evolutsioonietappi - asjade internetti (ingl Internet of Things, lüh IoT). IoT ei tähista ühtainsat tehnoloogiat, see võimaldab eri seadmeil - arvutid, mobiiltelefonid, autod, kodumasinad, loomad, virtuaalsensorid, jne - omavahel üle Interneti suhelda, vajamata seejuures pidevat inimesepoolset seadistamist ja juhtimist. Mobiilseadmetest nagu näiteks nutitelefon ja tahvelarvuti on saanud meie igapäevased kaaslased ning oma mitmekülgse võimekusega on nad motiveerinud teadustegevust mobiilse IoT vallas. Nutitelefonid kätkevad endas võimekaid protsessoreid ja 3G/4G tehnoloogiatel põhinevaid internetiühendusi. Kuid kui kasutada seadmeid järjepanu täisvõimekusel, tühjeneb mobiili aku kiirelt. Doktoritöö esitleb energiasäästlikku, kergekaalulist mobiilsete veebiteenuste raamistikku anduriandmete kogumiseks, kasutades kergemaid, energiasäästlikumaid suhtlustprotokolle, mis on IoT keskkonnale sobilikumad. Doktoritöö käsitleb põhjalikult energia kokkuhoidu mobiilteenuste majutamisel. Töö käigus loodud raamistikud on kontseptsiooni tõestamiseks katsetatud mitmetes juhtumiuuringutes päris seadmetega.The Internet has evolved, over the years, from just being the Internet to become the Internet of Things (IoT), the next step in its evolution. IoT is not a single technology and it enables about everything from computers, mobile phones, cars, appliances, animals, virtual sensors, etc. that connect and interact with each other over the Internet to function free from human interaction. Mobile devices like the Smartphone and tablet PC have now become essential to everyday life and with extended capabilities have motivated research related to the mobile Internet of Things. Although, the recently developed Smartphones enjoy the high performance and high speed 3G/4G mobile Internet data transmission services, such high speed performances quickly drain the battery power of the mobile device. This thesis presents an energy efficient lightweight mobile Web service provisioning framework for mobile sensing utilizing the protocols that were designed for the constrained IoT environment. Lightweight protocols provide an energy efficient way of communication. Finally, this thesis highlights the energy conservation of the mobile Web service provisioning, the developed framework, extensively. Several case studies with the use of the proposed framework were implemented on real devices and has been thoroughly tested as a proof-of-concept.https://www.ester.ee/record=b522498

Combining MAS and P2P Systems: The Agent Trees Multi-Agent System (ATMAS)

The seamless retrieval of information distributed across networks has been one of the key goals of many systems. Early solutions involved the use of single static agents which would retrieve the unfiltered data and then process it. However, this was deemed costly and inefficient in terms of the bandwidth since complete files need to be downloaded when only a single value is often all that is required. As a result, mobile agents were developed to filter the data in situ before returning it to the user. However, mobile agents have their own associated problems, namely security and control. The Agent Trees Multi-Agent System (AT-MAS) has been developed to provide the remote processing and filtering capabilities but without the need for mobile code. It is implemented as a Peer to Peer (P2P) network of static intelligent cooperating agents, each of which control one or more data sources. This dissertation describes the two key technologies have directly influenced the design of ATMAS, Peer-to-Peer (P2P) systems and Multi-Agent Systems (MAS). P2P systems are conceptually simple, but limited in power, whereas MAS are significantly more complex but correspondingly more powerful. The resulting system exhibits the power of traditional MAS systems while retaining the simplicity of P2P systems. The dissertation describes the system in detail and analyses its performance

Combining MAS and P2P systems : the Agent Trees Multi-Agent System (ATMAS)

The seamless retrieval of information distributed across networks has been one of the key goals of many systems. Early solutions involved the use of single static agents which would retrieve the unfiltered data and then process it. However, this was deemed costly and inefficient in terms of the bandwidth since complete files need to be downloaded when only a single value is often all that is required. As a result, mobile agents were developed to filter the data in situ before returning it to the user. However, mobile agents have their own associated problems, namely security and control. The Agent Trees Multi-Agent System (AT-MAS) has been developed to provide the remote processing and filtering capabilities but without the need for mobile code. It is implemented as a Peer to Peer (P2P) network of static intelligent cooperating agents, each of which control one or more data sources. This dissertation describes the two key technologies have directly influenced the design of ATMAS, Peer-to-Peer (P2P) systems and Multi-Agent Systems (MAS). P2P systems are conceptually simple, but limited in power, whereas MAS are significantly more complex but correspondingly more powerful. The resulting system exhibits the power of traditional MAS systems while retaining the simplicity of P2P systems. The dissertation describes the system in detail and analyses its performance.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Understanding the thermal evolution of earth

Studying the thermal history of Earth's mantle can provide a better understanding of Earth's evolution on a planetary scale. In this work, several mechanisms affecting the thermal evolution of Earth's mantle are investigated. The Nusselt-Rayleigh power law relationship (Nu(Ra)) was calculated from the results of a series of models with three dimensional spherical geometry and free slip boundary conditions. Basally and internally heated convection was examined. For Nu(Ra) = aRaP, (5 was found to be 0.294 0.004 for basally heated systems and 0.337 0.009 for internally heated systems. Model cases were extended to Rayleigh numbers higher than any previous study (109). 0 was not observed to reduce at high Rayleigh number, therefore, as this mechanism cannot be invoked to moderate thermal flux in the past, the influence of time dependent layering on thermal evolution was considered. A parameter space exploration of Rayleigh number and 660 km phase change Clapeyron slope demonstrates that present day Earth could have a partially layered mantle and that full two layer convection is possible in the past at higher Rayleigh numbers. Evolution of mantle temperature was modelled, with the models cooling from an initially layered state. As layering breaks down at high Rayleigh numbers, the mantle passes through a wide domain of partial layering before achieving whole mantle convection. The partially layered regime is characterised by a series of avalanches from the upper into the lower mantle. When an avalanche reaches the core mantle boundary it triggers a pulse of plume-like instabilities in the opposing hemisphere, producing a pulse in global surface heat flux. As the mantle cools, the avalanche-pulse events evolve towards higher frequency and lower magnitude. If this mechanism occurs within Earth, the gradualist view of Earth's thermal evolution may need to yield to a more event-driven model. The mechanics of avalanche-pulse events could also provide an explanation for geochemical observations of periodic maxima in melt extraction from the mantle. The modelling of Earth's mantle produces large data volumes. A distributed computing solution to the data storage problem was investigated. The system, MantleStor, is based on Peer-to-Peer technology and intended to operate over hundreds of standard workstations. A trial implementation demonstrates that MantleStor is able to safely store data in a challenging network environment. Data integrity was maintained with over 30% loss of storage machines. MantleStor is an example of an e-Science project, a discussion of e-Science and its implications is presented.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Understanding the thermal evolution of earth

Studying the thermal history of Earth's mantle can provide a better understanding of Earth's evolution on a planetary scale. In this work, several mechanisms affecting the thermal evolution of Earth's mantle are investigated. The Nusselt-Rayleigh power law relationship (Nu(Ra)) was calculated from the results of a series of models with three dimensional spherical geometry and free slip boundary conditions. Basally and internally heated convection was examined. For Nu(Ra) = aRaP, (5 was found to be 0.294 0.004 for basally heated systems and 0.337 0.009 for internally heated systems. Model cases were extended to Rayleigh numbers higher than any previous study (109). 0 was not observed to reduce at high Rayleigh number, therefore, as this mechanism cannot be invoked to moderate thermal flux in the past, the influence of time dependent layering on thermal evolution was considered. A parameter space exploration of Rayleigh number and 660 km phase change Clapeyron slope demonstrates that present day Earth could have a partially layered mantle and that full two layer convection is possible in the past at higher Rayleigh numbers. Evolution of mantle temperature was modelled, with the models cooling from an initially layered state. As layering breaks down at high Rayleigh numbers, the mantle passes through a wide domain of partial layering before achieving whole mantle convection. The partially layered regime is characterised by a series of avalanches from the upper into the lower mantle. When an avalanche reaches the core mantle boundary it triggers a pulse of plume-like instabilities in the opposing hemisphere, producing a pulse in global surface heat flux. As the mantle cools, the avalanche-pulse events evolve towards higher frequency and lower magnitude. If this mechanism occurs within Earth, the gradualist view of Earth's thermal evolution may need to yield to a more event-driven model. The mechanics of avalanche-pulse events could also provide an explanation for geochemical observations of periodic maxima in melt extraction from the mantle. The modelling of Earth's mantle produces large data volumes. A distributed computing solution to the data storage problem was investigated. The system, MantleStor, is based on Peer-to-Peer technology and intended to operate over hundreds of standard workstations. A trial implementation demonstrates that MantleStor is able to safely store data in a challenging network environment. Data integrity was maintained with over 30% loss of storage machines. MantleStor is an example of an e-Science project, a discussion of e-Science and its implications is presented