An efficient method to include equality constraints in branch current distribution system state estimation

Distribution system state estimation is a fundamental tool for the management and control functions envisaged for future distribution grids. The design of accurate and efficient algorithms is essential to provide estimates compliant with the needed accuracy requirements and to allow the real-time operation of the different applications. To achieve such requirements, peculiarities of the distribution systems have to be duly taken into account. Branch current-based estimators are an efficient solution for performing state estimation in radial or weakly meshed networks. In this paper, a simple technique, which exploits the particular formulation of the branch current estimators, is proposed to deal with zero injection and mesh constraints. Tests performed on an unbalanced IEEE 123-bus network show the capability of the proposed method to further improve efficiency performance of branch current estimators

GPU-Accelerated Algorithms for Compressed Signals Recovery with Application to Astronomical Imagery Deblurring

Compressive sensing promises to enable bandwidth-efficient on-board compression of astronomical data by lifting the encoding complexity from the source to the receiver. The signal is recovered off-line, exploiting GPUs parallel computation capabilities to speedup the reconstruction process. However, inherent GPU hardware constraints limit the size of the recoverable signal and the speedup practically achievable. In this work, we design parallel algorithms that exploit the properties of circulant matrices for efficient GPU-accelerated sparse signals recovery. Our approach reduces the memory requirements, allowing us to recover very large signals with limited memory. In addition, it achieves a tenfold signal recovery speedup thanks to ad-hoc parallelization of matrix-vector multiplications and matrix inversions. Finally, we practically demonstrate our algorithms in a typical application of circulant matrices: deblurring a sparse astronomical image in the compressed domain

Organization of aerobactin, hemolysin, and antibacterial resistance genes in lactose negative Escherichia coli strains of serotype O4 isolated from children with dhiarrea

Epidemiologically related, non-lactose-fermenting (NLF) Escherichia coli strains of serotype O4 have been isolated at a high frequency from children with diarrhea in Somalia (M. Nicoletti, F. Superti, C. Conti, A. Calconi, and C. Zagaglia, J. Clin. Microbiol. 26:524-529, 1988). In order to define the virulence potential of these strains, we characterized the replication properties of their high-molecular-weight plasmids and studied the genetic locations and organization of the aerobactin (aer) and hemolysin (hly) determinants encoded by 23 NLF O4 E. coli strains. Southern blot hybridizations, mobilization assays of nonconjugative plasmids, and incompatibility-exclusion experiments conducted with a conjugative incompatibility group FI (IncFI) plasmid showed that (i) 20 out of the 23 strains examined harbor a 160- to 180-kb IncFI plasmid that shares homology with the basic replicons RepFIA, RepFIB, and (except for the plasmid of one strain) RepFIC, and 22 strains also contain a 40- to 140-kb IncFII plasmid sharing homology with the RepFIIA replicon; (ii) the IncFI plasmid is nonconjugative and carries antibiotic resistance genes; (iii) the aer system is located on the IncFI plasmids and/or the chromosomes in the three strains not harboring IncFI, and it is found in an inverted orientation; (iv) the hly determinants are located on the chromosome, and their genetic organization is well conserved and closely resembles that of the reference hemolytic plasmid pHly152; and (v) Hly- mutants obtained by transposon insertion mutagenesis are not cytotoxic to HeLa cell monolayers, indicating that hemolysin is responsible for the high cytotoxic activity we have previously reported for these strains. The structural organization of the plasmid-encoded aer operon, together with the finding that those plasmids also carry antibiotic resistance genes, indicates that the IncFI plasmid of the NLF O4 E. coli strains studied more closely resembles aer-encoding virulence IncFI Salmonella R plasmids than E. coli ColV plasmids. The data presented here cannot rule out whether the strains examined are potentially intestinal or extraintestinal pathogens. Nevertheless, the genetic organization of the virulence genes, together with the epidemiological behavior and the wide spectrum of antibiotic resistance of the NLF O4 E. coli strains, indicates that these strains are structured as typical E. coli pathogenic isolates of human origin

The Minimal Landau Background Gauge on the Lattice

We present the first numerical implementation of the minimal Landau background gauge for Yang-Mills theory on the lattice. Our approach is a simple generalization of the usual minimal Landau gauge and is formulated for general SU(N) gauge group. We also report on preliminary tests of the method in the four-dimensional SU(2) case, using different background fields. Our tests show that the convergence of the numerical minimization process is comparable to the case of a null background. The uniqueness of the minimizing functional employed is briefly discussed.Comment: 5 pages, 1 tabl

Roles of stiffness and excluded volume in DNA denaturation

The nature and the universal properties of DNA thermal denaturation are investigated by Monte Carlo simulations. For suitable lattice models we determine the exponent c describing the decay of the probability distribution of denaturated loops of length l, $P \sim l^{-c}$. If excluded volume effects are fully taken into account, c= 2.10(4) is consistent with a first order transition. The stiffness of the double stranded chain has the effect of sharpening the transition, if it is continuous, but not of changing its order and the value of the exponent c, which is also robust with respect to inclusion of specific base-pair sequence heterogeneities.Comment: RevTeX 4 Pages and 4 PostScript figures included. Final version as publishe

Peculiar scaling of self-avoiding walk contacts

The nearest neighbor contacts between the two halves of an N-site lattice self-avoiding walk offer an unusual example of scaling random geometry: for N going to infinity they are strictly finite in number but their radius of gyration Rc is power law distributed, ~ Rc^{-\tau}, where \tau>1 is a novel exponent characterizing universal behavior. A continuum of diverging lengths scales is associated to the Rc distribution. A possibly super-universal \tau=2 is also expected for the contacts of a self-avoiding or random walk with a confining wall.Comment: 4 pages, 5 Postscript figures, uses psfig.sty; some sentences clarifie

Ampiezza e tassi dei movimenti verticali a Capo Vaticano (Calabria occidentale,Italia) negli ultimi 20 mila anni determinati sulla base di cunei progradanti epiattaforme di abrasione.

Ampiezza e tassi dei movimenti tettonici verticali sono stati quantificati nel settore offshore di Capo Vaticano (Calabria occidentale), nell’intervallo Pleistocene superiore – Olocene, sulla base delle profondità del ciglio dei cunei progradanti infralitorali e delle piattaforme di abrasione formatesi durante l’ultimo massimo glaciale (LGM). I cunei progradanti sono stati riconosciuti in profili sismici a riflessione ad alta risoluzione Sparker. I dati sismici sono stati acquisiti lungo la piattaforma e la scarpata continentale superiore, durante le crociere oceanografiche Marisk 2010 e 2012 organizzate dall’IAMC del CNR di Napoli, il DISTEM dell’Università di Palermo e il Dip. di Scienze della Terra dell’Università di Napoli. La deformazione tettonica verticale del promontorio di Capo Vaticano e del suo prolungamento offshore è caratterizzata da una marcata asimmetria, con profondità dei cigli dei cunei infralitorali che si approfondisce progressivamente procedendo verso NE. La rimozione della componente non tettonica dei movimenti verticali, ottenuta utilizzando dati sulle variazioni glacio-eustatiche del tardo Quaternario [Lambeck et al., 2011], indica nell’area in esame ~11 (± 5) m di sollevamento e di ~25 (± 5) m di subsidenza, nell’intervallo post-LGM, muovendoci da sud-ovest verso nord-est, su una distanza di ~22 km. Il valore medio del tasso di sollevamento e di subsidenza (considerando la componente sia regionale sia locale) per gli ultimi 20.350 (± 1,35) anni sono pari a 0,52 (± 0,28) mm/anno e di 1,23 (± 0,32) mm/anno, rispettivamente. I valori dell’ampiezza e il pattern dei movimenti verticali ottenuti attraverso l’analisi dei cunei progradanti infralitorali sono comparabili, sebbene a tassi parzialmente differenti, sia con quelli determinati attraverso marker geomorfologici tardo Olocenici [Spampinato et al., 2012] che con i tassi di sollevamento a lungo termine calcolati sulla base delle posizioni dei terrazzi marini formatisi a 80 a 215 mila anni [Cucci & Tertulliani, 2010]. L’integrazione dei nuovi dati con quelli disponibili in letteratura indica che il basculamento del promontorio di Capo Vaticano è episodico ed è avvenuto principalmente tra 215 e 125 mila anni e nel post-LGM

Infrared properties of propagators in Landau-gauge pure Yang-Mills theory at finite temperature

The finite-temperature behavior of gluon and of Faddeev-Popov-ghost propagators is investigated for pure SU(2) Yang-Mills theory in Landau gauge. We present nonperturbative results, obtained using lattice simulations and Dyson-Schwinger equations. Possible limitations of these two approaches, such as finite-volume effects and truncation artifacts, are extensively discussed. Both methods suggest a very different temperature dependence for the magnetic sector when compared to the electric one. In particular, a clear thermodynamic transition seems to affect only the electric sector. These results imply in particular the confinement of transverse gluons at all temperatures and they can be understood inside the framework of the so-called Gribov-Zwanziger scenario of confinement.Comment: 25 pages, 14 figures, 2 tables, minor changes of typographical and design character, some minor errors corrected, version to appear in PR