Fault-Tolerant Aggregation: Flow-Updating Meets Mass-Distribution

Flow-Updating (FU) is a fault-tolerant technique that has proved to be efficient in practice for the distributed computation of aggregate functions in communication networks where individual processors do not have access to global information. Previous distributed aggregation protocols, based on repeated sharing of input values (or mass) among processors, sometimes called Mass-Distribution (MD) protocols, are not resilient to communication failures (or message loss) because such failures yield a loss of mass. In this paper, we present a protocol which we call Mass-Distribution with Flow-Updating (MDFU). We obtain MDFU by applying FU techniques to classic MD. We analyze the convergence time of MDFU showing that stochastic message loss produces low overhead. This is the first convergence proof of an FU-based algorithm. We evaluate MDFU experimentally, comparing it with previous MD and FU protocols, and verifying the behavior predicted by the analysis. Finally, given that MDFU incurs a fixed deviation proportional to the message-loss rate, we adjust the accuracy of MDFU heuristically in a new protocol called MDFU with Linear Prediction (MDFU-LP). The evaluation shows that both MDFU and MDFU-LP behave very well in practice, even under high rates of message loss and even changing the input values dynamically.Comment: 18 pages, 5 figures, To appear in OPODIS 201

GaN and InN nanowires grown by MBE: a comparison

Morphological, optical and transport properties of GaN and InN nanowires grown by molecular beam epitaxy (MBE) have been studied. The differences between the two materials in respect to growth parameters and optimization procedure was stressed. The nanowires crystalline quality has been investigated by means of their optical properties. A comparison of the transport characteristics was given. For each material a band schema was shown, which takes into account transport and optical features and is based on Fermi level pinning at the surface.Comment: 5 pages, 5 figure

The flat building in Znojmo

Bakalářská práce se zabývá návrhem novostavby bytového domu. Bytový dům se nachází v okrajové části města Znojma. Stavba je situovaná v zastavěné oblasti, určené převážně k bydlení. Objekt je řešen jako samostatně stojící, v rovinatém terénu. Jedná se o třípodlažní, nepodsklepený objekt, ukončený plochou střechou. V prvním nadzemním podlaží se nachází garáže, společné prostory a technická místnost. V druhém a třetím nadzemním podlaží se nachází 4 bytové jednotky, které jsou dispozičně totožné. Jedná se o byty 3+1. Stavba je založena na základových pásech z prostého betonu a je vyzděna ze stavebního systému Porotherm.The bachelor thesis deals with proposal of the new flat building. The flat building is located in the edge part of Znojmo. The building is situated in built-up area, intended for housing. The building is solved as detached house in the flat terrain. This is a three-storey building without cellar, which is finished by warm flat roof. On the ground floor there is a garage, a common spaces and a utility room. On the first and second floor there is four dwelling units, which are identical layout. There are flats 3+1. The building is based on foundation strips from concrete strip footing and is made by the building system Porotherm.