30,506 research outputs found

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

    Get PDF
    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

    In-plane thermal conductivity of large single crystals of Sm-substituted (Y1x_{1-x}Smx_{x})Ba2_{2}Cu3_{3}O7δ_{7-\delta}

    Full text link
    We have investigated the in-plane thermal conductivity κab(T,H)\kappa_{ab}(T,H) of large single crystals of optimally oxygen-doped (Y1x_{1-x},Smx_{x})Ba2_{2}Cu3_{3}O7δ_{7-\delta} (xx=0, 0.1, 0.2 and 1.0) and YBa2_{2}(Cu1y_{1-y}Zny_{y})3_{3}O7δ_{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 0\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 0\ell_{0} .Comment: 7 pages,4 figures,1 tabl

    Reply to Comment on "Quantum phase transition in the four-spin exchange antiferromagnet"

    Full text link
    We argue that our analysis of the J-Q model, presented in Phys. Rev. B 80, 174403 (2009), and based on a field-theory description of coupled dimers, captures properly the strong quantum fluctuations tendencies, and the objections outlined by L. Isaev, G. Ortiz, and J. Dukelsky, arXiv:1003.5205, are misplaced

    Time-odd triaxial relativistic mean field approach for nuclear magnetic moments

    Get PDF
    The time-odd triaxial relativistic mean field approach is developed and applied to the investigation of the ground-state properties of light odd-mass nuclei near the double-closed shells. The nuclear magnetic moments including the isoscalar and isovector ones are calculated and good agreement with Schmidt values is obtained. Taking 17^{17}F as an example, the splitting of the single particle levels (around  0.7~0.7 MeV near the Fermi level), the nuclear current, the core polarizations, and the nuclear magnetic potential, i.e., the spatial part of the vector potential, due to the violation of the time reversal invariance are investigated in detail.Comment: 26 pages, 8 figures. PHYSICAL REVIEW C (accepted

    Edge states and topological orders in the spin liquid phases of star lattice

    Full text link
    A group of novel materials can be mapped to the star lattice, which exhibits some novel physical properties. We give the bulk-edge correspondence theory of the star lattice and study the edge states and their topological orders in different spin liquid phases. The bulk and edge-state energy structures and Chern number depend on the spin liquid phases and hopping parameters because the local spontaneous magnetic flux in the spin liquid phase breaks the time reversal and space inversion symmetries. We give the characteristics of bulk and edge energy structures and their corresponding Chern numbers in the uniform, nematic and chiral spin liquids. In particular, we obtain analytically the phase diagram of the topological orders for the chiral spin liquid states SL[\phi,\phi,-2\phi], where \phi is the magnetic flux in two triangles and a dodecagon in the unit cell. Moreover, we find the topological invariance for the spin liquid phases, SL[\phi_{1},\phi_{2},-(\phi_{1}+\phi_{2})] and SL[\phi_{2},\phi_{1},-(\phi_{1}+\phi_{2})]. The results reveal the relationship between the energy-band and edge-state structures and their topological orders of the star lattice.Comment: 7 pages, 8 figures, 1 tabl

    Nanodot-Cavity Electrodynamics and Photon Entanglement

    Full text link
    Quantum electrodynamics of excitons in a cavity is shown to be relevant to quantum operations. We present a theory of an integrable solid-state quantum controlled-phase gate for generating entanglement of two photons using a coupled nanodot-microcavity-fiber structure. A conditional phase shift of O(π/10)O(\pi/10) is calculated to be the consequence of the giant optical nonlinearity keyed by the excitons in the cavities. Structural design and active control, such as electromagnetic induced transparency and pulse shaping, optimize the quantum efficiency of the gate operation.Comment: 4 pages 3 figure

    Charge transport and electron-hole asymmetry in low-mobility graphene/hexagonal boron nitride heterostructures

    Full text link
    Graphene/hexagonal boron nitride (G/hh-BN) heterostructures offer an excellent platform for developing nanoelectronic devices and for exploring correlated states in graphene under modulation by a periodic superlattice potential. Here, we report on transport measurements of nearly 00^{\circ}-twisted G/hh-BN heterostructures. The heterostructures investigated are prepared by dry transfer and thermally annealing processes and are in the low mobility regime (approximately 3000 cm2V1s13000~\mathrm{cm}^{2}\mathrm{V}^{-1}\mathrm{s}^{-1} at 1.9 K). The replica Dirac spectra and Hofstadter butterfly spectra are observed on the hole transport side, but not on the electron transport side, of the heterostructures. We associate the observed electron-hole asymmetry to the presences of a large difference between the opened gaps in the conduction and valence bands and a strong enhancement in the interband contribution to the conductivity on the electron transport side in the low-mobility G/hh-BN heterostructures. We also show that the gaps opened at the central Dirac point and the hole-branch secondary Dirac point are large, suggesting the presence of strong graphene-substrate interaction and electron-electron interaction in our G/hh-BN heterostructures. Our results provide additional helpful insight into the transport mechanism in G/hh-BN heterostructures.Comment: 7 pages, 4 figure

    Benchmark generator for CEC 2009 competition on dynamic optimization

    Get PDF
    Evolutionary algorithms(EAs) have been widely applied to solve stationary optimization problems. However, many real-world applications are actually dynamic. In order to study the performance of EAs in dynamic environments, one important task is to develop proper dynamic benchmark problems. Over the years, researchers have applied a number of dynamic test problems to compare the performance of EAs in dynamic environments, e.g., the “moving peaks ” benchmark (MPB) proposed by Branke [1], the DF1 generator introduced by Morrison and De Jong [6], the singleand multi-objective dynamic test problem generator by dynamically combining different objective functions of exiting stationary multi-objective benchmark problems suggested by Jin and Sendhoff [2], Yang and Yao’s exclusive-or (XOR) operator [10, 11, 12], Kang’s dynamic traveling salesman problem (DTSP) [3] and dynamic multi knapsack problem (DKP), etc. Though a number of DOP generators exist in the literature, there is no unified approach of constructing dynamic problems across the binary space, real space and combinatorial space so far. This report uses the generalized dynamic benchmark generator (GDBG) proposed in [4], which construct dynamic environments for all the three solution spaces. Especially, in the rea
    corecore