684 research outputs found
Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration
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
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
Motivated by iodo platinum complexes assembled within a quadratic-prism
lattice, [Pt(CHN)(CHN)I](NO), 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)
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Synchronisation schemes for two dimensional discrete systems
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
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
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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