Renormalization of cellular automata and self-similarity

We study self-similarity in one-dimensional probabilistic cellular automata (PCA) using the renormalization technique. We introduce a general framework for algebraic construction of renormalization groups (RG) on cellular automata and apply it to exhaustively search the rule space for automata displaying dynamic criticality. Previous studies have shown that there exists several exactly renormalizable deterministic automata. We show that the RG fixed points for such self-similar CA are unstable in all directions under renormalization. This implies that the large scale structure of self-similar deterministic elementary cellular automata is destroyed by any finite error probability. As a second result we show that the only non-trivial critical PCA are the different versions of the well-studied phenomenon of directed percolation. We discuss how the second result supports a conjecture regarding the universality class for dynamic criticality defined by directed percolation.Comment: 14 pages, 4 figure

Neutrino oscillation studies with IceCube-DeepCore

AbstractIceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed

Investigation of the effect of phase conjugation and time reversal techniques in free space and reverberant environment

We numerically explore the performance of the time reversal approach in terms of temporal and spatial focussing in three different propagation environments: free space, partially reflected medium and fully reflected medium. Performance of the phase conjugation scheme is experimentally investigated in partially reflected medium and fully reflected medium based on the characteristics of focus sing and steering capabilities. We have explored numerically the E-field time evolution along the propagation path and the beam steering action of a 2.45 GHz time reversal retrodirective array using dipole antennas excited by a I0nS 2.45 GHz RP pulsed sinusoidal carrier. It is shown that temporal and spatially confined focussing can be achieved for a variety of different time reversal methods, un-modified, amplitude quantised and time decimated under sampled with a single transmitter and a receiver setup operating within a reverberation chamber at 2.4 GHz under RP pulsed sinewave. Also it has been shown that, by introducing various size cluttering objects into the reverberant environment, the application of classical and differential time reversal methods does not significantly affect the spatio-temporal focus sing properties of the system. The possibility of deploying multiple transmitters inside the cavity is also briefly investigated. We have numerically demonstrated that temporal, spatial focussing and beam steering action can be achieved in free space using a slot array positioned in one wall of a metal air filled cavity utilizing a single antenna time reversal system. This presents an interesting possibility for a new type of beam steered array. The phase conjugation technique is an alternative to the time reversal method, which is suitable for monochromatic signals. Various phase conjugation implementation techniques have been developed for retrodirective array deployment this thesis employs a QUB developed IQ modulator based phase conjugator. It is experimentally shown that spatial localization of the field occurs within a radius of approximately 1.5-2A around the pilot source position using the single analogue phase conjugation unit operating at 2.4GHz for spatially confined data signaling in an enclosed highly reverberant multipath rich environment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Instantiating uninterpreted functional units and memory system: Functional verification of the VAMP

Abstract. In the VAMP (verified architecture microprocessor) project we have designed, functionally verified, and synthesized a processor with full DLX instruction set, delayed branch, Tomasulo scheduler, maskable nested precise interrupts, pipelined fully IEEE compatible dual precision floating point unit with variable latency, and separate instruction and data caches. The verification has been carried out in the theorem proving system PVS. The processor has been implemented on a Xilinx FPGA.

Potencial atrator de peixes ósseos em recife artificial no litoral norte do estado do Rio de Janeiro, Brasil Attractor potential of osteichthyes in artificial reef on the northern coast of Rio de Janeiro State, Brazil

<abstract language="eng">Artificial reefs have become an important and popular resource enhancement technique by concentrating fishes and by increasing natural production of biological resources. In order to increase the necto-benthic colonization potencial, an artificial reef was installed on the northern coast of Rio de Janeiro (21º27'S, 41ºOO'W), an area with typically low relief bottom. Measuring nearly 1500 m², the reef consisted of four sets of different materials randomly disposed: concrete pipes (N = 12); tires structures (N = 20); and cement tanks (N = 7) and pre-made blocks (N = 4). ln order to determine the artificial reef effects on the teleost community, trammel nets were used for monthly sampling the reef site (RA) and on a control area (AC) with sandy bottom. During the 23-month survey from April/96 to March/98, were recorded: a) Chaetodipterus faber (Broussonet, 1782) and Haemulon aurolieatum (Cuvier, 1829) as exclusive species of the RA; b) higher values of species richness and abundance on the RA, at least in 5 of 8 periods; c) increase on the fish abundance on summer months. Correlation analysis indicated that salinity and precipitation were the most significant environmental factors correlated with the temporal fish community variation. This results highlight the importance of rainfall periodicity and the influence of Paraíba do Sul River on the nekton assemblage distribution. It is suggested that the functional role of the artificial reef might be related to higher availability of local shelter and food resources