237 research outputs found
Study of Transient Interaction in a System with Transformer Supplied from Network through a Cable: Assessment of Interaction Frequencies and Resonance Evolvement
Transformer together with its windings is a complex oscillatory system. The interaction between
the transformer and an electric network during transients can cause the development of resonance
phenomenon in the windings leading to overvoltages and the risk of transformer fault.
This report presents the results of studies of resonance phenomena in transformer windings,
caused by interaction with an electric network containing the feeder cable. The approach to a simple
assessment of dominant oscillation frequency of a voltage in the system âfeeder cable â transformerâ and
estimation of the resonant frequencies of transformer winding is considered. The report also describes
the technique for measurement of winding resonance voltages. The resonance phenomenon evolvement
in transformer windings is considered and the impact of decaying oscillating applied voltage on maximum
ratio of resonance overvoltages is estimated
A 3D Finite-Difference BiCG Iterative Solver with the Fourier-Jacobi Preconditioner for the Anisotropic EIT/EEG Forward Problem
The Electrical Impedance Tomography (EIT) and electroencephalography (EEG) forward problems in anisotropic inhomogeneous media like the human head belongs to the class of the three-dimensional boundary value problems for elliptic equations with mixed derivatives. We introduce and explore the performance of several new promising numerical techniques, which seem to be more suitable for solving these problems. The proposed numerical schemes combine the fictitious domain approach together with the finite-difference method and the optimally preconditioned Conjugate Gradient- (CG-) type iterative method for treatment of the discrete model. The numerical scheme includes the standard operations of summation and multiplication of sparse matrices and vector, as well as FFT, making it easy to implement and eligible for the effective parallel implementation. Some typical use cases for the EIT/EEG problems are considered demonstrating high efficiency of the proposed numerical technique
Cupriferous basalts of the Northern Urals
Characteristics and distinctive features of cupriferous basalts in the world are given. Deposits of the Superior Lake in the United States are considered as a reference. In the Northern Urals, drilling explored the Khultymâinsk mineralized zone, associated with almond-stone olivine basalts and their tuffs of different granulometry. A detailed study of a new for the Urals type of copper mineralization into basalts for their conformity with known cupriferous volcanites. The main ore mineral is native copper, up to 10 mm size. Analysis of the distribution of native copper and sulphide mineralization in space according to drilling data made it possible to reveal mineral zonality in the area: the central part contains the releases of native copper, sulfide mineralization is developed on the periphery (both above and below in the section and in the flank parts), closer to the centre with a poor dissemination of chalcopyrite, and at a distance - pyrite. As a whole, the Khultymâinskaya mineralized zone has a gentle dip, thickness of up to 166-228 m and extent of up to 3500 m, including the intervals with the development of native copper, was discovered by drilling. This mineralized zone has been traced by inclination of more than 500 m. Despite its wide distribution, the mineralization is very dispersed and according to the results of testing the copper content is extremely low (less than 0.1%), and only a small number of samples contain more than 0.5% copper. Relatively elevated concentrations of copper (from 0.1 to >1%) are localized in spatially disconnected, small-sized bodies. The mineralized zone is controlled by thrust, it is probable that the ore-bearing fluids have been inflated over this structures. A copper ore manifestation of a new type, unconventional for the Urals with a stratified deposit of disseminated native copper in the basic section of the Upper Tournaisian age, has been revealed. The large areas occupied by rift basalts on the eastern slope of the Northern Urals make it possible to assume the prospect of this type mineralisation. Rift structures of Eastern Siberia are potential as well
Coulomb dissociation of N 20,21
Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,Îł)N20 and N20(n,Îł)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,Îł)N20 rate is up to a factor of 5 higher at
Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires
The production of tt⟠, W+bb⟠and W+cc⟠is studied in the forward region of protonâproton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fbâ1 . The W bosons are reconstructed in the decays WââÎœ , where â denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of , and is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 0.02 \mbox{fb}^{-1}. The bosons are reconstructed in the decays , where denotes muon or electron, while the and quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions
Measurement of CP violation parameters and polarisation fractions in decays
The first measurement of asymmetries in the decay and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of and . Together with constraints from , the results are used to constrain additional contributions due to penguin diagrams in the -violating phase , measured through decays to charmonium.The first measurement of CP asymmetries in the decay and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of 3.0 fb^{â}^{1} of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Together with constraints from B â J/Ï Ï, the results are used to constrain additional contributions due to penguin diagrams in the CP -violating phase Ï , measured through B decays to charmonium.The first measurement of asymmetries in the decay and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of and . Together with constraints from , the results are used to constrain additional contributions due to penguin diagrams in the -violating phase , measured through decays to charmonium
Measurement of the J/Ï pair production cross-section in pp collisions at TeV
The production cross-section of J/Ï pairs is measured using a data sample of pp collisions collected by the LHCb experiment at a centre-of-mass energy of TeV, corresponding to an integrated luminosity of 279 ±11 pb. The measurement is performed for J/Ï mesons with a transverse momentum of less than 10 GeV/c in the rapidity range 2.0 < y < 4.5. The production cross-section is measured to be 15.2 ± 1.0 ± 0.9 nb. The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the J/Ï pair are measured and compared to theoretical predictions.The production cross-section of pairs is measured using a data sample of collisions collected by the LHCb experiment at a centre-of-mass energy of , corresponding to an integrated luminosity of . The measurement is performed for mesons with a transverse momentum of less than in the rapidity range . The production cross-section is measured to be . The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the pair are measured and compared to theoretical predictions
Measurement of forward production in collisions at TeV
A measurement of the cross-section for production in collisions is presented using data corresponding to an integrated luminosity of fb collected by the LHCb experiment at a centre-of-mass energy of TeV. The electrons are required to have more than GeV of transverse momentum and to lie between 2.00 and 4.25 in pseudorapidity. The inclusive production cross-sections, where the decays to , are measured to be \begin{align*} \begin{split} \sigma_{W^{+} \to e^{+}\nu_{e}}&=1124.4\pm 2.1\pm 21.5\pm 11.2\pm 13.0\,\mathrm{pb},\\ \sigma_{W^{-} \to e^{-}\bar{\nu}_{e}}&=\,\,\,809.0\pm 1.9\pm 18.1\pm\,\,\,7.0\pm \phantom{0}9.4\,\mathrm{pb}, \end{split} \end{align*} where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. Differential cross-sections as a function of the electron pseudorapidity are measured. The cross-section ratio and production charge asymmetry are also reported. Results are compared with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. Finally, in a precise test of lepton universality, the ratio of boson branching fractions is determined to be \begin{align*} \begin{split} \mathcal{B}(W \to e\nu)/\mathcal{B}(W \to \mu\nu)=1.020\pm 0.002\pm 0.019, \end{split} \end{align*} where the first uncertainty is statistical and the second is systematic.A measurement of the cross-section for production in collisions is presented using data corresponding to an integrated luminosity of fb collected by the LHCb experiment at a centre-of-mass energy of TeV. The electrons are required to have more than GeV of transverse momentum and to lie between 2.00 and 4.25 in pseudorapidity. The inclusive production cross-sections, where the decays to , are measured to be \begin{equation*} \sigma_{W^{+} \to e^{+}\nu_{e}}=1124.4\pm 2.1\pm 21.5\pm 11.2\pm 13.0\,\mathrm{pb}, \end{equation*} \begin{equation*} \sigma_{W^{-} \to e^{-}\bar{\nu}_{e}}=\,\,\,809.0\pm 1.9\pm 18.1\pm\,\,\,7.0\pm \phantom{0}9.4\,\mathrm{pb}, \end{equation*} where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. Differential cross-sections as a function of the electron pseudorapidity are measured. The cross-section ratio and production charge asymmetry are also reported. Results are compared with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. Finally, in a precise test of lepton universality, the ratio of boson branching fractions is determined to be \begin{equation*} \mathcal{B}(W \to e\nu)/\mathcal{B}(W \to \mu\nu)=1.020\pm 0.002\pm 0.019, \end{equation*} where the first uncertainty is statistical and the second is systematic.A measurement of the cross-section for W â eÎœ production in pp collisions is presented using data corresponding to an integrated luminosity of 2 fb collected by the LHCb experiment at a centre-of-mass energy of TeV. The electrons are required to have more than 20 GeV of transverse momentum and to lie between 2.00 and 4.25 in pseudorapidity. The inclusive W production cross-sections, where the W decays to eÎœ, are measured to be where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination
Measurement of the B0sâÎŒ+ÎŒâ Branching Fraction and Effective Lifetime and Search for B0âÎŒ+ÎŒâ Decays
A search for the rare decays Bs0âÎŒ+ÎŒ- and B0âÎŒ+ÎŒ- is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4ââfb-1. An excess of Bs0âÎŒ+ÎŒ- decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(Bs0âÎŒ+ÎŒ-)=(3.0±0.6-0.2+0.3)Ă10-9, where the first uncertainty is statistical and the second systematic. The first measurement of the Bs0âÎŒ+ÎŒ- effective lifetime, Ï(Bs0âÎŒ+ÎŒ-)=2.04±0.44±0.05ââps, is reported. No significant excess of B0âÎŒ+ÎŒ- decays is found, and a 95% confidence level upper limit, B(B0âÎŒ+ÎŒ-)<3.4Ă10-10, is determined. All results are in agreement with the standard model expectations.A search for the rare decays and is performed at the LHCb experiment using data collected in collisions corresponding to a total integrated luminosity of 4.4 fb. An excess of decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be , where the first uncertainty is statistical and the second systematic. The first measurement of the effective lifetime, ps, is reported. No significant excess of decays is found and a 95 % confidence level upper limit, , is determined. All results are in agreement with the Standard Model expectations
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