41 research outputs found

    Multiphysics coupled simulations of gas turbines

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    The resolution of differential equations of diverse degree of complexity is necessary to simulate the phenomena present in the complex turbomachinery flows and in particular, requires accounting for unsteady effects that may have a preponderant role. Today, only the LES (Large Eddy Simulation) fully compressible approach has the required accuracy to predict the physics associated to reactive and turbulent flows in such complex geometries. This work covers the numerical modelling of physics in the near-wall region of a high-pressure turbine blade with special focus on thermal predictions. This work was supported by the European project COPA-GT, dedicated to the numerical multi-physics simulation of a complete gas turbine

    On F-theory Quiver Models and Kac-Moody Algebras

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    We discuss quiver gauge models with bi-fundamental and fundamental matter obtained from F-theory compactified on ALE spaces over a four dimensional base space. We focus on the base geometry which consists of intersecting F0=CP1xCP1 Hirzebruch complex surfaces arranged as Dynkin graphs classified by three kinds of Kac-Moody (KM) algebras: ordinary, i.e finite dimensional, affine and indefinite, in particular hyperbolic. We interpret the equations defining these three classes of generalized Lie algebras as the anomaly cancelation condition of the corresponding N =1 F-theory quivers in four dimensions. We analyze in some detail hyperbolic geometries obtained from the affine A base geometry by adding a node, and we find that it can be used to incorporate fundamental fields to a product of SU-type gauge groups and fields.Comment: 13 pages; new equations added in section 3, one reference added and typos correcte

    On Local F-theory Geometries and Intersecting D7-branes

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    We discuss local F-theory geometries and theirs gauge theory dualities in terms of intersecting D7-branes wrapped four-cycles in Type IIB superstring. The manifolds are built as elliptic K3 surface fibrations over intersecting F_0=CP^1 \times CP^1 base geometry according to ADE Dynkin Diagrams. The base is obtained by blowing up the extended ADE hyper-Kahler singularities of eight dimensional manifolds considered as sigma model target spaces with eight supercharges. The resulting gauge theory of such local F-theory models are given in terms of Type IIB D7-branes wrapped intersecting F_0. The four dimensional N=1 anomaly cancelation requirement translates into a condition on the associated affine Lie algebras.Comment: 16 pages, 1 figure, Reference added, published in IJGMMP (2009

    Topological charges and the genus of surfaces

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    We show that the topological charge of the n-soliton solution of the sine-Gordon equation n is related to the genus g > 1 of a constant negative curvature compact surface described by this configuration. The relation is n=2(g-1), where n is even. The moduli space of complex dimension B(g)=3(g-1) corresponds precisely to the freedom to choosing the configuration with n solitons of arbitrary positions and velocities. We speculate also that the odd soliton states will describe the unoriented surfaces.Comment: 8 pages, Latex. To be published in Journal of Geommetry and Physic

    On Hexagonal Structures in Higher Dimensional Theories

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    We analyze the geometrical background under which many Lie groups relevant to particle physics are endowed with a (possibly multiple) hexagonal structure. There are several groups appearing, either as special holonomy groups on the compactification process from higher dimensions, or as dynamical string gauge groups; this includes groups like SU(2),SU(3), G_2, Spin(7), SO(8) as well as E_8 and SO(32). We emphasize also the relation of these hexagonal structures with the octonion division algebra, as we expect as well eventually some role for octonions in the interpretation of symmetries in High Energy Physics.Comment: 9 pages, Latex, 3 figures. Accepted for publication in International Journal of Theoretical Physic

    Timed artificial insemination (TAI) based on CIDR first, second or third use in Bos indicus cows

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    The study aimed to verify the effects of CIDR (P4) first, second or third use on PR in protocols for TAI. Five hundred and forty-seven Nelore cows were divided: CIDR1 (CIDR first use; n=196); CIDR2 (second use; n=188) and CIDR3 (third use; n=163). All animals were submitted to the same protocol: day 0(d0), 2mg EB+CIDR1, CIDR2 or CIDR3, according the CIDR use; d9, CIDR removal + 12.5 dinoprost thrometamin+0.6mg ECP + 48 hours calf removal; d11, TAI + return of the calves to dams. The overall pregnancy rate (PR) was 63.8, 53.7 and 27.0% for CIDR1, CIDR2, and CIDR3, respectively. Differences in the PR were observed between: CIDR1 and CIDR2 (P=0.04); CIDR1 and CIDR3 (P=0.0001); and CIDR2 and CIDR3 (P=0.0001). The open days (OD) in post partum and body condition score (BCS) resulted in differences (P<0.05) among groups. There was a correlation between open days in CIDR 1 and 2 versus BCS, as well as between BCS of the CIDR 1 and 3 against PR In conclusion, CIDR1 showed better reproductive efficiency than CIDR2 and CIDR3 use. Differences were observed between the groups in regard to DO, and by cows submitted to CIDR earlier in the postpartum period having a lower PR than those submitted at a later time. A BCS of 3.1 resulted in a higher PR than those with 3.5 and 3.7.

    Los departamentos de Expresión Gráfica Arquitectónica desde la experiencia en Análisis de Formas Arquitectónicas

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    Junta de Andalucía-Consejería de Política TerritorialEscuela Técnica Superior de Arquitectura de la Universidad de SevillaExcmo. Ayuntamiento de SevillaColegio Oficial de Arquitectos de Andalucía Occidenta

    EFICIÊNCIA DA GONADOTROFINA CORIÔNICA EQÜINA (eCG) E DO DESMAME TEMPORÁRIO (DT) EM PROTOCOLOS PARA A INSEMINAÇÃO ARTIFICIAL EM TEMPO FIXO (IATF) EM VACAS NELORE, PREVIAMENTE TRATADAS COM PROGESTERONA(P4) E BENZOATO DE ESTRADIOL (BE).

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    O objetivo do estudo foi checar a eficiência reprodutiva da eCG e do desmame temporário em protocolos para IATF em vacas Nelore pluríparas, previamente tratadas com progesterona intravaginal e benzoato de estradiol (BE). Foram utilizadas 343 animais, com ECC médio de 2,65 (1=magra; 5= gorda), no período pós parto (media 51,9 dias), e divididas em dois grupos(G): GeCG (grupo gonadotrofina coriônica eqüina; n=144) recebeu no dia 0 (d0) 0,558 g de P4 + 1,0 mg de BE; em d8 (remoção da P4 + 0,075 mg de PGF2 alfa+1,5 mg de cipionato de estradiol–ECP + 400UI de eCG); em d10 execução da IATF; o GDT (grupo desmame temporário; n=199) o mesmo que GeCG  sem eCG no d8, e com desmame temporário por 48 horas e retorno dos bezerros às mães no dia da IATF(d10). A taxa de prenhez (TP) à IATF, após 35 dias resultou em 59,0 e 63,3 % respectivamente para os GeCG e GDT ( P>0,05) e a TP  à  IATF + o repasse com touros, em 90,9 e 95,9 % (P=0,056), após 90 dias de estação de monta. Concluiu-se que ambos os protocolos mostraram-se eficientes em fazendas comerciais de bovinos de corte, enfatizando-se a utilização do DT onde haja facilidade de manejo
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