716 research outputs found
Empirical assessment of the critical time increment in explicit particulate discrete element method simulations
This contribution considers the critical time increment (〖∆t〗_crit) to achieve stable simulations using particulate discrete element method (DEM) codes that adopt a Verlet-type time integration scheme. The 〖∆t〗_crit is determined by considering the maximum vibration frequency of the system. Based on a series of parametric studies, 〖∆t〗_crit is shown to depend on the particle mass (m), the maximum contact stiffness (Kmax), and the maximum particle coordination number (CN,max). Empirical expressions relating 〖∆t〗_crit to m, Kmax, and CN,max are presented; while strictly only valid within the range of simulation scenarios considered here, these can inform DEM analysts selecting appropriate 〖∆t〗_crit values
Empirical assessment of the critical time increment in explicit particulate discrete element method simulations
This contribution considers the critical time increment (〖∆t〗_crit) to achieve stable simulations using particulate discrete element method (DEM) codes that adopt a Verlet-type time integration scheme. The 〖∆t〗_crit is determined by considering the maximum vibration frequency of the system. Based on a series of parametric studies, 〖∆t〗_crit is shown to depend on the particle mass (m), the maximum contact stiffness (Kmax), and the maximum particle coordination number (CN,max). Empirical expressions relating 〖∆t〗_crit to m, Kmax, and CN,max are presented; while strictly only valid within the range of simulation scenarios considered here, these can inform DEM analysts selecting appropriate 〖∆t〗_crit values
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
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
IAC 576 - cultivar de mandioca de mesa recomendada para Mato Grosso do Sul.
bitstream/item/24714/1/COT200380.pdfDocumento on-line
Isolamento e seleção de rizóbios de solos de Mato Grosso Do Sul para inoculação em feijoeiro comum
bitstream/item/66207/1/32003.pdfFERTBI
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
Avaliação de clones IAC de mandioca da geração 1996, nas condições edafoclimáticas de Dourados, MS.
Publicado também na: RAT: Revista Raízes e Amidos Tropicais, v. 3, 2007. (SEP 035)
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