Connectivity for the frisbee architecture

In this paper we investigate the kconnectivity threshold of distributed dense ad hoc heterogeneous wireless sensor network architecture. We consider the situation when sensors are deployed in the surveillance area according to a uniform distribution perturbed by a Gaussian noise. We derive analytically the minimum detection range which guarantees an emerging structure in the network, namely the connectivity, which becomes larger and larger as the number of sensors in the network increase. This allows the target track to be propagated almost surely throughout the network using the minimum possible amount ofprime energy. We report the results of some simulation experiments which further support the theoretical results

Algorithms for the selection of the active sensors in distributed tracking: Comparison between Frisbee and GNS methods

This paper compares two different approaches for sensor selection for distributed tracking: 1) The Frisbee method, and 2) Global Node Selection (GNS). The Frisbee method is based on the proximity of the nodes to the predicted location of the target; GNS is based on minimizing the unbiased Cramer Rao lower bound (CRLB). Both theoretical and experimental results indicate that the Frisbee method is as effective as GNS. Furthermore, the Frisbee method is attractive due to its very light computational load

Resource optimisation in a wireless sensor network with guaranteed estimator performance

New control paradigms are needed for large networks of wireless sensors and actuators in order to efficiently utilise system resources. In this study, the authors consider the problem of discrete-time state estimation over a wireless sensor network. Given a tree that represents the sensor communications with the fusion centre, the authors derive the optimal estimation algorithm at the fusion centre, and provide a closedform expression for the steady-state error covariance matrix. They then present a tree reconfiguration algorithm that produces a sensor tree that has low overall energy consumption and guarantees a desired level of estimation quality at the fusion centre. The authors further propose a sensor tree construction and scheduling algorithm that leads to a longer network lifetime than the tree reconfiguration algorithm. Examples are provided throughout the paper to demonstrate the algorithms and theory developed

Local renormalization method for random systems

In this paper, we introduce a real-space renormalization transformation for random spin systems on 2D lattices. The general method is formulated for random systems and results from merging two well known real space renormalization techniques, namely the strong disorder renormalization technique (SDRT) and the contractor renormalization (CORE). We analyze the performance of the method on the 2D random transverse field Ising model (RTFIM).Comment: 12 pages, 13 figures. Submitted to the Special Issue on "Quantum Information and Many-Body Theory", New Journal of Physics. Editors: M.B. Plenio, J. Eiser

Second-order electronic correlation effects in a one-dimensional metal

The Pariser-Parr-Pople (PPP) model of a single-band one-dimensional (1D) metal is studied at the Hartree-Fock level, and by using the second-order perturbation theory of the electronic correlation. The PPP model provides an extension of the Hubbard model by properly accounting for the long-range character of the electron-electron repulsion. Both finite and infinite version of the 1D-metal model are considered within the PPP and Hubbard approximations. Calculated are the second-order electronic-correlation corrections to the total energy, and to the electronic-energy bands. Our results for the PPP model of 1D metal show qualitative similarity to the coupled-cluster results for the 3D electron-gas model. The picture of the 1D-metal model that emerges from the present study provides a support for the hypothesis that the normal metallic state of the 1D metal is different from the ground state.Comment: 21 pages, 16 figures; v2: small correction in title, added 3 references, extended and reformulated a few paragraphs (detailed information at the end of .tex file); added color to figure

Census Transform Based Optical Flow for Motion Detection during Different Sinusoidal Brightness Variations

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Modelling hospital bed necessity for COVID-19 patients during the decline phase of the epidemic trajectory

BACKGROUND: In the present study we aimed to create a model able to predict the short-term need of hospital beds for COVID-19 patients, during SARS-CoV-2 outbreak. METHODS: We retrospectively revised data about all COVID-19 patients hospitalized at a University Hospital in Northern Italy, between March 1 and April 29, 2020. Several polynomial models (from first to fourth order) were fitted to estimate the relationship between the time and the number of occupied hospital beds during the entire period and after the local peak of the outbreak and to provide the prediction of short-term hospital beds demand. Model selection was based on the adjusted R2 (aR2) Index and likelihood ratio test (LRT). RESULTS: We included 836 hospitalizations (800 COVID-19 patients). The median length of hospital in-stay was 12 days. According to the aR2, the fourth order models best fitted the data considering the entire time period. When only the data after the peak was selected, no statistical improvement was found adding terms of order 3 and 4 and lower order polynomial models were considered for the forecasting of the hospital beds demand. Both approaches had a decreasing trend in the number of occupied beds along with time; however, the quadratic one showed a faster reduction in the predicted number of beds required by patients affected by COVID-19. CONCLUSIONS: We propose a model to predict the hospital bed requirement during the descending phase of COVID-19 outbreak, the validation of which might contribute to decision makers policy in the next weeks of pandemic

Power laws in a 2-leg ladder of interacting spinless fermions

We use the Density-Matrix Renormalization Group to study the single-particle and two-particle correlation functions of spinless fermions in the ground state of a quarter-filled ladder. This ladder consists of two chains having an in-chain extended Coulomb interaction reaching to third neighbor and coupled by inter-chain hopping. Within our short numerical coherence lengths, typically reaching ten to twenty sites, we find a strong renormalization of the interchain hopping and the existence of a dimensional crossover at smaller interactions. We also find power exponents for single-particle hopping and interchain polarization consistent with the single chain. The total charge correlation function has a larger power exponent and shows signs of a crossover from incoherent fermion hopping to coherent particle-hole pair motion between chains. There are no significant excitation energies.Comment: RevTex 4 file, 10 pages, 10 eps figure