38,158 research outputs found

    Meta-heuristic algorithms in car engine design: a literature survey

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    Meta-heuristic algorithms are often inspired by natural phenomena, including the evolution of species in Darwinian natural selection theory, ant behaviors in biology, flock behaviors of some birds, and annealing in metallurgy. Due to their great potential in solving difficult optimization problems, meta-heuristic algorithms have found their way into automobile engine design. There are different optimization problems arising in different areas of car engine management including calibration, control system, fault diagnosis, and modeling. In this paper we review the state-of-the-art applications of different meta-heuristic algorithms in engine management systems. The review covers a wide range of research, including the application of meta-heuristic algorithms in engine calibration, optimizing engine control systems, engine fault diagnosis, and optimizing different parts of engines and modeling. The meta-heuristic algorithms reviewed in this paper include evolutionary algorithms, evolution strategy, evolutionary programming, genetic programming, differential evolution, estimation of distribution algorithm, ant colony optimization, particle swarm optimization, memetic algorithms, and artificial immune system

    MOCVD synthesis of compositionally tuned topological insulator nanowires

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    Device applications involving topological insulators (TIs) will require the development of scalable methods for fabricating TI samples with sub-micron dimensions, high quality surfaces, and controlled compositions. Here we use Bi-, Se-, and Te-bearing metalorganic precursors to synthesize TIs in the form of nanowires. Single crystal nanowires can be grown with compositions ranging from Bi2Se3 to Bi2Te3, including the ternary compound Bi2Te2Se. These high quality nanostructured TI compounds are suitable platforms for on-going searches for Majorana Fermions

    In-plane thermal conductivity of large single crystals of Sm-substituted (Y1−x_{1-x}Smx_{x})Ba2_{2}Cu3_{3}O7−δ_{7-\delta}

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    We have investigated the in-plane thermal conductivity κab(T,H)\kappa_{ab}(T,H) of large single crystals of optimally oxygen-doped (Y1−x_{1-x},Smx_{x})Ba2_{2}Cu3_{3}O7−δ_{7-\delta} (xx=0, 0.1, 0.2 and 1.0) and YBa2_{2}(Cu1−y_{1-y}Zny_{y})3_{3}O7−δ_{7-\delta}(yy=0.0071) as functions of temperature and magnetic field (along the c axis). For comparison, the temperature dependence of κab\kappa_{ab} for as-grown crystals with the corresponding compositions are presented. The nonlinear field dependence of κab\kappa_{ab} for all crystals was observed at relatively low fields near a half of TcT_{c}. We make fits of the κ(H)\kappa(H) data to an electron contribution model, providing both the mean free path of quasiparticles ℓ0\ell_{0} and the electronic thermal conductivity κe\kappa_{e}, in the absence of field. The local lattice distortion due to the Sm substitution for Y suppresses both the phonon and electron contributions. On the other hand, the light Zn doping into the CuO 2_{2} planes affects solely the electron component below TcT_{c}, resulting in a substantial decrease in ℓ0\ell_{0} .Comment: 7 pages,4 figures,1 tabl

    Analysis on the hull girder ultimate strength of a bulk carrier using simplified method based on an incremental-iterative approach

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    The hull girder ultimate strength of a typical bulk carrier is analyzed using a simplified method based on an incremental-iterative approach. First, vertical bending moment is examined by seven different methods. The moment versus curvature curves and the values of the ultimate longitudinal moments at collapse states are determined for both hogging and sagging cases. Second, the ultimate strength under coupled vertical and horizontal bending moment is accounted. An interaction curve is obtained, which corresponds to the results of series of calculation for the ship hull subject to bending conditions with different angles of curvature. It is found that the interaction curve is asymmetrical because the hull cross section is not symmetrical with respect to the horizontal axis and the structural response of the elements under compression is different from that under tension due to nonlinearity caused by buckling. The angles of the resultant bending moment vector and that of the curvature vector are different in investigated cases. The interaction design equations proposed by other researches are also addressed to discuss the results presented by this study

    Pointed Hopf Algebras with classical Weyl Groups

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    We prove that Nichols algebras of irreducible Yetter-Drinfeld modules over classical Weyl groups Aâ‹ŠSnA \rtimes \mathbb S_n supported by Sn\mathbb S_n are infinite dimensional, except in three cases. We give necessary and sufficient conditions for Nichols algebras of Yetter-Drinfeld modules over classical Weyl groups Aâ‹ŠSnA \rtimes \mathbb S_n supported by AA to be finite dimensional.Comment: Combined with arXiv:0902.4748 plus substantial changes. To appear International Journal of Mathematic

    Modular polyoxometalate-layered double hydroxide composites as efficient oxidative catalysts

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    The exploitation of intercalation techniques in the field of two-dimensional layered materials offers unique opportunities for controlling chemical reactions in confined spaces and developing nanocomposites with desired functionality. In this paper, we demonstrate the exploitation of the novel and facile ‘one-pot’ anion-exchange method for the functionalization of layered double hydroxides (LDHs). As a proof of concept, we demonstrate the intercalation of a series of polyoxometalate (POM) clusters, Na3[PW12O40]•15H2O (Na3PW12), K6[P2W18O62]•14H2O (K6P2W18), and Na9LaW10O36•32H2O (Na9LaW10) into tris(hydroxymethyl)amino-methane (Tris) modified layered double hydroxides (LDHs) under ambient conditions without the necessity of degassing CO2. Investigation of the resultant intercalated materials of Tris-LDHs-PW12 (1), Tris-LDH-P2W18 (2), and Tris-LDH-LaW10 (3) for the degradation of methylene blue (MB), rhodamine B (RB) and crystal violet (CV) has been carried out, where Tris-LDH-PW12 reveals the best performance in the presence of H2O2. Additionally, degradation of a mixture of RB, MB and CV by Tris-LDH-PW12 follows the order of CV > MB > RB, which is directly related to the designed accessible area of the interlayer space. Also, the composite can be readily recycled and reused at least ten cycles without measurable decrease of activity

    Nondecoupling of Heavy Fermions and a Special Yukawa Texture

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    Talk based on work entitled ``Yukawa textures, new physics and nondecoupling,'' done in collaboration with G. C. Branco and J. I. Silva-Marcos, arXiv:hep-ph/0612252, to appear in Phys. Rev. D. In this work we pointed out that New Physics can play an important r\^ ole in rescuing some of the Yukawa texture zero ans\" atze which would otherwise be eliminated by the recent, more precise measurements of VCKMV_{CKM}. We have shown that the presence of an isosinglet vector-like quark which mixes with standard quarks, can render viable a particularly interesting four texture zero Yukawa ansatz. The crucial point is the nondecoupling of the effects of the isosinglet quark, even for arbitrary large values of its mass.Comment: Invited talk at CTP Symposium on Supersymmetry at LHC: Theoretical and Experimental Prospectives, Cairo, Egypt, 11-14 Mar 200
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