Efecto de la inyeccion de agua en un acuifero confinado

[Effect of water injection into a confined aquifer

Computational study on the stability of lean CH4-air and H2-CH4-air laminar premixed flames

Recently, Shoshin et al. [1] reported measurements on blow-off limits for methane-air and hydrogen-methaneair flames stabilized on metallic rods finding a so-called "anomalous" blow-off behaviour of hydrogen-methaneair flames with certain hydrogen content. It is well known that lean methane-air and hydrogen-methane-air flames have characteristics that differ substantially owing to preferential diffusion effects. In this study, two-dimensional simulations of steady, rod-stabilized, inverted, lean, methaneair and hydrogen-methane-air premixed laminar flames are performed to further investigate the stability and blowoff characteristics of such flames. The simulations are carried out with complex chemistry and non-unity Lewis transport. For the hydrogen-methane-air flames, mixtures with a 40% (molar based) hydrogen content in the fuel are considered. Six cases for different values of equivalence ratio, , and mean inlet velocity, V , of the premixed mixture are studied. The conditions for all the cases are summarized in Table 1. In what follows, the governing equations are provided, the burner and computational setup are described and the numerical results are discussed

Computational study on the stability of lean CH4-air and H2-CH4-air laminar premixed flames

Recently, Shoshin et al. [1] reported measurements on blow-off limits for methane-air and hydrogen-methaneair flames stabilized on metallic rods finding a so-called "anomalous" blow-off behaviour of hydrogen-methaneair flames with certain hydrogen content. It is well known that lean methane-air and hydrogen-methane-air flames have characteristics that differ substantially owing to preferential diffusion effects. In this study, two-dimensional simulations of steady, rod-stabilized, inverted, lean, methaneair and hydrogen-methane-air premixed laminar flames are performed to further investigate the stability and blowoff characteristics of such flames. The simulations are carried out with complex chemistry and non-unity Lewis transport. For the hydrogen-methane-air flames, mixtures with a 40% (molar based) hydrogen content in the fuel are considered. Six cases for different values of equivalence ratio, , and mean inlet velocity, V , of the premixed mixture are studied. The conditions for all the cases are summarized in Table 1. In what follows, the governing equations are provided, the burner and computational setup are described and the numerical results are discussed

Predictions of striking energy and angular dependence in pp --> (pp)_S-wave pi^0 production

A phenomenological calculation from threshold to 800 MeV of the initial proton beam energy is presented to describe recent data on the reaction pp --> (pp)_S-wave pi^0 with a low energy cut on the final state diproton excitation energy. A strong forward dip is obtained in the differential cross section as in the data from COSY at 800 MeV, although the absolute value of the forward cross section is too low. Earlier low energy data from CELSIUS are reasonably well reproduced. In the unexplored energy interval between these two experiments the model predicts a spectacular energy dependence both in the forward direction and in the angle-integrated cross section.Comment: 9 pages, 4 figure

Rational three-spin string duals and non-anomalous finite size effects

We determine by a one line computation the one-loop conformal dimension and the associated non-anomalous finite size correction for all operators dual to spinning strings of rational type having three angular momenta (J_1,J_2,J_3) on S^5. Finite size corrections are conjectured to encode information about string sigma model loop corrections to the spectrum of type IIB superstrings on AdS_5xS^5. We compare our result to the zero-mode contribution to the leading quantum string correction derived for the stable three-spin string with two out of the three spin labels identical and observe agreement. As a side result we clarify the relation between the Bethe root description of three-spin strings of the type (J,J',J') with respectively J>J' and J<J'.Comment: 15 pages, v2: comparison to string theory changed, references added, v3: textual modifications and title change

Performance evaluation of an optical transparent access tier based on PON and spectral codes

The increasing amount of bandwidth requirements and quality of service needs for the next-generation access networks has boosted extensive research in the fiber-optics communication field. In this light, passive optical networks (PONs) combined with optical code division multiple access (OCDMA), provide a potentially cost-effective solution to meet such bandwidth demands. This work proposes an optical transparent architecture which enables all-optical communication between the network nodes. The encoded data streams are multiplexed at a merging point which results in multiple user interference (MUI), thus significantly reducing the network throughput. The networking nodes are able to monitor and record user activity in the PON, and further register the (past) state of activity at the merging point. In this work, we study the coherence of state between the networking nodes and the merging point, for different packet size distributions, in order to predict an optimal transmission instant of each node's data packets. We note that the states are coherent depending on the packet size distribution

Complete next-to-leading order calculation for pion production in nucleon-nucleon collisions at threshold

Based on a counting scheme that explicitly takes into account the large momentum sqrt(M m_pi) characteristic for pion production in nucleon-nucleon collisions we calculate all diagrams for the reaction NN --> NN pi at threshold up to next-to-leading order. At this order there are no free parameters and the size of the next-to-leading order contributions is in line with the expectation from power counting. The sum of loop corrections at that order vanishes for the process pp --> pp pi^0 at threshold. The total contribution at next-to-leading order from loop diagrams that include the delta degree of freedom vanishes at threshold in both reaction channels pp --> pp pi^0, pn pi^+.Comment: 9 pages, 4 figure

Harmonic index and harmonic polynomial on graph operations

Some years ago, the harmonic polynomial was introduced to study the harmonic topological index. Here, using this polynomial, we obtain several properties of the harmonic index of many classical symmetric operations of graphs: Cartesian product, corona product, join, Cartesian sum and lexicographic product. Some upper and lower bounds for the harmonic indices of these operations of graphs, in terms of related indices, are derived from known bounds on the integral of a product on nonnegative convex functions. Besides, we provide an algorithm that computes the harmonic polynomial with complexity O(n 2 ).This work was supported in part by two grants from Ministerio de Economía y Competititvidad, Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (MTM2016-78227-C2-1-P and MTM2017-90584-REDT), Spain

Landau-Lifshitz sigma-models, fermions and the AdS/CFT correspondence

We define Landau-Lifshitz sigma models on general coset space $G/H$, with $H$ a maximal stability sub-group of $G$. These are non-relativistic models that have $G$-valued N\"other charges, local $H$ invariance and are classically integrable. Using this definition, we construct the $PSU(2,2|4)/PS(U(2|2)^2)$ Landau-Lifshitz sigma-model. This sigma model describes the thermodynamic limit of the spin-chain Hamiltonian obtained from the complete one-loop dilatation operator of the N=4 super Yang-Mills (SYM) theory. In the second part of the paper, we identify a number of consistent truncations of the Type IIB Green-Schwarz action on $AdS_5\times S^5$ whose field content consists of two real bosons and 4,8 or 16 real fermions. We show that $\kappa$-symmetry acts trivially in these sub-sectors. In the context of the large spin limit of the AdS/CFT correspondence, we map the Lagrangians of these sub-sectors to corresponding truncations of the $PSU(2,2|4)/PS(U(2|2)^2)$ Landau-Lifshitz sigma-model.Comment: 42 page