Mechanisms of Water Droplets Deposition on Turbine Blade Surfaces and Erosion Wear Effects

Failure of turbine blades leads to various exploitation problems, efficiency decrease and economical losses, at all. A detailed research on aerodynamic features, in various exploitation conditions and regimes, and on reasons for failures, is a prerequisite to the obviated technical problems and increased reliability of turbine aggregates. Water droplets erosion is known as a very complex and crucial phenomena. It couples the effects of wet steam expansion, together with condensation (evaporation), presence of second phase with the impact of water droplets over blade surfaces, erosion effects and fatigue mechanisms. The present research deals with a logical sequence for numerical simulations and research on erosion mechanisms in a low pressure stage of К-1000-6 /1500 steam turbine, working at a Nuclear Power Plant. Attention is paid to the impact of droplets’ diameter on blade surfaces, their aerodynamic behavior and efficiency of energy conversion through turbine channels. Particular trajectories of water droplets, reasons for occurrence of erosion wear, over certain parts of the streamlined surfaces, are established and discussed. An approach to acquire incidence time to erosion appearance is implemented. Research methodology and obtained results are applicable to determine erosion effects on streamed complex surfaces, to replace expensive measurements campaigns, introduce approaches to decrease wetness in last stages of condensation turbines and prolong the reliability of blades operated in wet steam condition

Anyons and the Bose-Fermi duality in the finite-temperature Thirring model

Solutions to the Thirring model are constructed in the framework of algebraic QFT. It is shown that for all positive temperatures there are fermionic solutions only if the coupling constant is $\lambda=\sqrt{2(2n+1)\pi}, n\in {\bf N}$. These fermions are inequivalent and only for $n=1$ they are canonical fields. In the general case solutions are anyons. Different anyons (which are uncountably many) live in orthogonal spaces and obey dynamical equations (of the type of Heisenberg's "Urgleichung") characterized by the corresponding values of the statistic parameter. Thus statistic parameter turns out to be related to the coupling constant $\lambda$ and the whole Hilbert space becomes non-separable with a different "Urgleichung" satisfied in each of its sectors. This feature certainly cannot be seen by any power expansion in $\lambda$. Moreover, since the latter is tied to the statistic parameter, it is clear that such an expansion is doomed to failure and will never reveal the true structure of the theory. The correlation functions in the temperature state for the canonical dressed fermions are shown by us to coincide with the ones for bare fields, that is in agreement with the uniqueness of the $\tau$-KMS state over the CAR algebra ($\tau$ being the shift automorphism). Also the $\alpha$-anyon two-point function is evaluated and for scalar field it reproduces the result that is known from the literature.Comment: 25 pages, LaTe

In situ FT-IR investigation of the reduction of NO with CO over Au/CeO2-Al2O3 catalyst in the presence and absence of H-2

Cataloged from PDF version of article.he NO + CO + H-2 reaction over CeO2, Au/CeO2 (3 wt% Au), Au/CeO2-Al2O3 (2.9 wt% Au, 20 wt% Al2O3) and CeO2-Al2O3 mixed support prepared by co-precipitation has been Studied by FT-IR spectroscopy at elevated temperatures. Formation of NCO species has been detected on all of the samples. The presence of metallic gold is not necessary for the generation of the isocyanates on ceria and the mixed ceria-alumina support. The NCO species are produced by a process involving the dissociation of NO on the oxygen vacancies of the support, followed by the reaction between N atoms lying oil the surface and CO molecules. Gold plays an important role in the modification of ceria leading to Ce3+ and oxygen vacancies formation, and causes significant lowering of the reduction temperature of CeO2 and CeO2-Al2O3 enhancing the reducibility of ceria surface layers. The role of H-2 is to keep the surface reduced during the course of the reaction. The onset temperature, at which the interaction between the surface isocyanates and No begins, is low (100 degrees C). This explains the high activity of the Au/CeO2-Al2O3 catalyst with 100% selectivity in the reduction of NO by CO at low temperature (200 degrees C) and in the presence of H-2 (C) 2008 Elsevier B.V. All rights reserve

On Supergroups with Odd Clifford Parameters and Supersymmetry with Modified Leibniz Rule

We investigate supergroups with Grassmann parameters replaced by odd Clifford parameters. The connection with non-anticommutative supersymmetry is discussed. A Berezin-like calculus for odd Clifford variables is introduced. Fermionic covariant derivatives for supergroups with odd Clifford variables are derived. Applications to supersymmetric quantum mechanics are made. Deformations of the original supersymmetric theories are encountered when the fermionic covariant derivatives do not obey the graded Leibniz property. The simplest non-trivial example is given by the N=2 SQM with a real $(1,2,1)$ multiplet and a cubic potential. The action is real. Depending on the overall sign ("Euclidean" or "Lorentzian") of the deformation, a Bender-Boettcher pseudo-hermitian hamiltonian is encountered when solving the equation of motion of the auxiliary field. A possible connection of our framework with the Drinfeld twist deformation of supersymmetry is pointed out.Comment: Final version to be published in Int. J. Mod. Phys. A; 20 page

Monopole Vacuum in Non-Abelian Theories

It is shown that, in the theory of interacting Yang -Mills fields and a Higgs field, there is a topological degeneracy of Bogomol'nyi-Prasad-Sommerfield (BPS) monopoles and that there arises, in this case, a chromoelectric monopole characterized by a new topological variable that describes transitions between topological states of the monopole in the Minkowski space (in just the same way as an instanton describes such transitions in the Euclidean space). The limit of an infinitely large mass of the Higgs field at a finite density of the BPS monopole is considered as a model of the stable vacuum in the pure Yang-Mills theory. It is shown that, in QCD, such a monopole vacuum may lead to a rising potential, a topological confinement and an additional mass of the $\eta_0$ meson. The relationship between the result obtained here for the generating functional of perturbation theory and Faddeev-Popov integral is discussed

The electric dipole response of 76^{76}Se above 4 MeV

The dipole response of $^{76}_{34}$Se in the energy range 4 to 9 MeV has been analyzed using a $(\vec\gamma,{\gamma}')$ polarized photon scattering technique, performed at the High Intensity $\gamma$-Ray Source facility, to complement previous work performed using unpolarized photons. The results of this work offer both an enhanced sensitivity scan of the dipole response and an unambiguous determination of the parities of the observed J=1 states. The dipole response is found to be dominated by $E1$ excitations, and can reasonably be attributed to a pygmy dipole resonance. Evidence is presented to suggest that a significant amount of directly unobserved excitation strength is present in the region, due to unobserved branching transitions in the decays of resonantly excited states. The dipole response of the region is underestimated when considering only ground state decay branches. We investigate the electric dipole response theoretically, performing calculations in a 3D cartesian-basis time-dependent Skyrme-Hartree-Fock framework.Comment: 20 pages, 18 figures, to be submitted to PR

Gold catalysts supported on ceria doped by rare earth metals for water gas shift reaction: Influence of the preparation method

Cataloged from PDF version of article.Gold catalysts based on ceria, doped by various RE metals (La, Sm, Gd, Yb, Y) were studied. The influence of the preparation methods on structure, properties and catalytic activity in the WGS reaction was investigated. The catalysts' supports were prepared using two different methods: co-precipitation (CP) and mechanochemical activation (MA). The catalysts were tested in a wide temperature interval without and after reactivation. All samples were characterized using a combination of X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS) and TPR. It was found that the catalytic activity of MA catalysts is higher than CP ones. The gold catalysts based on ceria doped by Yb and Sm exhibited the highest activity. After reactivation in air the MA samples almost kept the WGS activity same, while the CP catalysts increased it. The catalysts of a single- and double-phase structure are formed as a result of CP and MA preparation, respectively. There are no big differences in the gold particles size (2-3 nm) depending on dopants and on the preparation techniques. The RS spectra analysis indicates that most probably the oxygen vacancies are adjacent to Me(3+) dopant and the ceria structure seems to be better ordered than in the case of alumina as a dopant. There is no distinct correlation between reducibility and WGS activity. The XPS analysis disclose positively charged gold particles in addition to metallic gold within a surface region of fresh samples and only metallic gold on the samples after catalytic processing. There is no simple correlation between the concentration of Ce(3+) in the samples and their WGS activity. (C) 2009 Elsevier B.V. All rights reserved

β decay of semi-magic 130Cd: Revision and extension of the level scheme of 130 In

A. Jungclaus et al.; 8 págs.; 5 figs.; 3 tabs.The β decay of the semi-magic nucleus Cd130 has been studied at the RIBF facility at the RIKEN Nishina Center. The high statistics of the present experiment allowed for a revision of the established level scheme of In130 and the observation of additional β feeding to high-lying core-excited states in In130. The experimental results are compared to shell-model calculations employing a model space consisting of the full major N=50-82 neutron and Z=28-50 proton shells and the NA-14 interaction, and good agreement is found. ©2016 American Physical SocietyWe thank the staff of the RIKEN Nishina Center accelerator complex for providing stable beams with high intensities to the experiment. We acknowledge the EUROBALL Owners Committee for the loan of germanium detectors and the PreSpec Collaboration for the readout electronics of the cluster detectors. This work was supported by the Spanish Ministerio de Ciencia e Innovación under contract FPA2011-29854-C04 and the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2014-57196-C5- 4-P, the Generalitat Valenciana (Spain) under Grant No. PROMETEO/2010/101, the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (NRF-2014S1A2A2028636, 2016K1A3A7A09005579), the Priority Centers Research Program in Korea (2009-0093817), OTKA Contract No. K-100835, JSPS KAKENHI (Grant No. 25247045), the European Commission through the Marie Curie Actions call FP7-PEOPLE-2011-IEF under Contract No. 300096, the US Department of Energy, Office of Nuclear Physics, under Contract No.DE-AC02-06CH11357, the STFC (UK), the “RIKEN foreign research program,” the German BMBF (No. 05P12RDCIA, No. 05P12RDNUP, and No. 05P12PKFNE), HIC for FAIR, the DFG cluster of excellence “Origin and Structure of the Universe,” and DFG (Contract No. KR2326/2-1).Peer Reviewe