5,952 research outputs found

    A high specific capacity membraneless aluminum-air cell operated with an inorganic/organic hybrid electrolyte

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    Aluminum-air cells have attracted a lot of interests because they have the highest volumetric capacity density in theory among the different metal-air systems. To overcome the self-discharge issue of aluminum, a microfluidic aluminum-air cell working with KOH methanol-based anolyte was developed in this work. A specific capacity up to 2507 mAh g¯¹ (that is, 84.1% of the theoretical value) was achieved experimentally. The KOH concentration and water content in the methanol-based anolyte were found to have direct influence on the cell performance. A possible mechanism of the aluminum reactions in KOH methanol-based electrolyte was proposed to explain the observed phenomenon

    Anisotropic Magneto-conductance of InAs Nanowire: Angle Dependent Suppression of 1D Weak Localization

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    The magneto-conductance of an InAs nanowire is investigated with respect to the relative orientation between external magnetic field and the nanowire axis. It is found that both the perpendicular and the parallel magnetic fields induce a positive magneto-conductance. Yet the parallel magnetic field induced longitudinal magneto-conductance has a smaller magnitude. This anisotropic magneto-transport phenomenon is studied as a function of temperature, magnetic field strength and at an arbitrary angle between the magnetic field and the nanowire. We show that the observed effect is in quantitative agreement with the suppression of one-dimensional (1D) weak localization

    Model Counting for Formulas of Bounded Clique-Width

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    We show that #SAT is polynomial-time tractable for classes of CNF formulas whose incidence graphs have bounded symmetric clique-width (or bounded clique-width, or bounded rank-width). This result strictly generalizes polynomial-time tractability results for classes of formulas with signed incidence graphs of bounded clique-width and classes of formulas with incidence graphs of bounded modular treewidth, which were the most general results of this kind known so far.Comment: Extended version of a paper published at ISAAC 201

    ECONOMIC EVALUATION OF CROPSHARE AND CASH LEASE CONTRACTS IN SOUTH DAKOTA AND NEBRASKA

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    Factors influencing choice of share or cash rental leases for cropland are examined using a 1996 dataset containing 1071 lease contracts in Nebraska and in South Dakota. Logistic regression results indicate tenant's age, capital position, and relationship with landlord were more important than leased land use or crop management variables.Farm Management,

    Macroporous materials: microfluidic fabrication, functionalization and applications

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    This article provides an up-to-date highly comprehensive overview (594 references) on the state of the art of the synthesis and design of macroporous materials using microfluidics and their applications in different fields

    Polymeric templating synthesis of anatase TiOâ‚‚ nanoparticles from low-cost inorganic titanium sources

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    A novel facile and cost-effective synthesis method for anatase TiOâ‚‚ nanoparticles has been developed by using poly-acrylic acid hydrogel as template at room temperature. The newly developed synthesis method avoids the use of hazardous reagents and/or hydrothermal steps, and enables production of highly active TiOâ‚‚ nanoparticles from low cost inorganic titanium sources. The synthesized TiOâ‚‚ nanoparticles have been studied in several applications including dye-sensitized solar cells as a photoanode as well as in organics degradation of methyl orange in aqueous media. Good photocatalytic performances were obtained in both applications

    A computationally-efficient, semi-implicit, iterative method for the time-integration of reacting flows with stiff chemistry

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    A semi-implicit preconditioned iterative method is proposed for the time-integration of the stiff chemistry in simulations of unsteady reacting flows, such as turbulent flames, using detailed chemical kinetic mechanisms. Emphasis is placed on the simultaneous treatment of convection, diffusion, and chemistry, without using operator splitting techniques. The preconditioner corresponds to an approximation of the diagonal of the chemical Jacobian. Upon convergence of the sub-iterations, the fully-implicit, second-order time-accurate, Crank–Nicolson formulation is recovered. Performance of the proposed method is tested theoretically and numerically on one-dimensional laminar and three-dimensional high Karlovitz turbulent premixed n-heptane/air flames. The species lifetimes contained in the diagonal preconditioner are found to capture all critical small chemical timescales, such that the largest stable time step size for the simulation of the turbulent flame with the proposed method is limited by the convective CFL, rather than chemistry. The theoretical and numerical stability limits are in good agreement and are independent of the number of sub-iterations. The results indicate that the overall procedure is second-order accurate in time, free of lagging errors, and the cost per iteration is similar to that of an explicit time integration. The theoretical analysis is extended to a wide range of flames (premixed and non-premixed), unburnt conditions, fuels, and chemical mechanisms. In all cases, the proposed method is found (theoretically) to be stable and to provide good convergence rate for the sub-iterations up to a time step size larger than 1 μs. This makes the proposed method ideal for the simulation of turbulent flames

    Stress Relaxation in Entangled Polymer Melts

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    We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t)G(t), into the plateau regime for chains with Z=40Z=40 entanglements and into the terminal relaxation regime for Z=10Z=10. Using the known (Rouse) mobility of unentangled chains and the melt entanglement length determined via the primitive path analysis of the microscopic topological state of our systems, we have performed parameter -free tests of several different tube models. We find excellent agreement for the Likhtman-McLeish theory using the double reptation approximation for constraint release, if we remove the contribution of high-frequency modes to contour length fluctuations of the primitive chain.Comment: 5 pages, 3 figure
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