684 research outputs found

    Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

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    Oxygen concentration and separation is an essential factor for air recycling in a controlled ecological life support system (CELSS). Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of oxygen from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested

    Single crystal field-effect transistors based on an organic selenium-containing semiconductor

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    We report on the fabrication and characterization of single crystal field-effect transistors (FETs) based on diphenylbenzo diselenophene (DPh-BDSe). These organic field-effect transistors (OFETs) function as p-channel accumulation-mode devices. At room temperature, for the best devices, the threshold voltage is less than -7V and charge carrier mobility is nearly gate bias independent, ranging from 1cm2/Vs to 1.5 cm2/Vs depending on the source-drain bias. Mobility is increased slightly by cooling below room temperature and decreases below 280 K

    Competing Ground States of a Peierls-Hubbard Nanotube

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    Motivated by iodo platinum complexes assembled within a quadratic-prism lattice, [Pt(C2_2H8_8N2_2)(C10_{10}H8_8N2_2)I]4_4(NO3_3)8_8, we investigate the ground-state properties of a Peierls-Hubbard four-legged tube. Making a group-theoretical analysis, we systematically reveal a variety of valence arrangements, including half-metallic charge-density-wave states. Quantum and thermal phase competition is numerically demonstrated with particular emphasis on doping-induced successive insulator-to-metal transitions with conductivity increasing stepwise.Comment: 6 pages, 4 figures. to be published in Europhys. Lett. 87 (2009) 1700

    Synchronisation schemes for two dimensional discrete systems

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    In this work we consider two models of two dimensional discrete systems subjected to three different types of coupling and analyse systematically the performance of each in realising synchronised states.We find that linear coupling effectively introduce control of chaos along with synchronisation,while synchronised chaotic states are possible with an additive parametric coupling scheme both being equally relevant for specific applications.The basin leading to synchronisationin the initial value plane and the choice of parameter values for synchronisation in the parameter plane are isolatedin each case.Comment: 17 pages 8 figures. submitted to physica script

    6,7,6′,7′-Tetra­phenyl-2,2′-bi[1,3-dithia-5,8-diaza­cyclo­penta­[b]naphthalenyl­idene] chloro­form disolvate

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    The title compound, C42H24N4S4·2CHCl3, a symmetrical tetra­thia­fulvalene (TTF) derivative, was prepared by a tri­ethyl­phos­phite-mediated self-coupling reaction of 6,7-diphenyl-1,3-dithia-5,8-diaza­cyclo­penta­[b]napthalen-2-one. The asymmetric unit contains two TTF mol­ecules and four chloro­form solvent mol­ecules. Cl⋯Cl inter­actions [contact distances = 3.263 (1)–3.395 (2) Å] are present between the solvent mol­ecules, resulting in a tape along the bc plane. The crystal packing features weak C—H⋯Cl and C—H⋯N hydrogen bonds, resulting in the formation of a two-dimensional supramolecular network

    The influence of particle surface roughness on elastic stiffness and dynamic response

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    Discrete-element method (DEM) simulations of planar wave propagation are used to examine the effect of particle surface roughness on the stiffness and dynamic response of granular materials. A new contact model that considers particle surface roughness is implemented in the DEM simulations. Face-centred cubic lattice packings and random configurations are used; uniform spheres are considered in both cases to isolate fabric and contact model effects from inertia effects. For the range of values considered here surface roughness caused a significant reduction in stiffness, particularly at lower confining stresses. The simulations confirm that surface roughness effects can at least partially explain the value of the exponent in the relationship between stiffness and mean confining stress for an assembly of spherical particles. Frequency domain analyses showed that the maximum frequency transmitted through the sample is reduced when surface roughness is considered. The assumption of homogeneity of stress and contacts in analytical micromechanical models is shown to lead to an overestimation of stiffness
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