2,561 research outputs found
Conceptualisation of an Efficient Particle-Based Simulation of a Twin-Screw Granulator
Discrete Element Method (DEM) simulations have the potential to provide particle-scale understanding of twin-screw granulators. This is difficult to obtain experimentally because of the closed, tightly confined geometry. An essential prerequisite for successful DEM modelling of a twin-screw granulator is making the simulations tractable, i.e., reducing the significant computational cost while retaining the key physics. Four methods are evaluated in this paper to achieve this goal: (i) develop reduced-scale periodic simulations to reduce the number of particles; (ii) further reduce this number by scaling particle sizes appropriately; (iii) adopt an adhesive, elasto-plastic contact model to capture the effect of the liquid binder rather than fluid coupling; (iv) identify the subset of model parameters that are influential for calibration. All DEM simulations considered a GEA ConsiGma™ 1 twin-screw granulator with a 60° rearward configuration for kneading elements. Periodic simulations yielded similar results to a full-scale simulation at significantly reduced computational cost. If the level of cohesion in the contact model is calibrated using laboratory testing, valid results can be obtained without fluid coupling. Friction between granules and the internal surfaces of the granulator is a very influential parameter because the response of this system is dominated by interactions with the geometry
Experimental study of anisotropy and non-coaxiality of granular solids
Previous experimental studies of anisotropy and non-coaxiality by using the hollow cylindrical apparatus are mainly focused on granular soils, which feature irregular particle shapes and non-uniform particle size distributions. This paper experimentally investigates these two characteristics on assemblages of particulate materials with regular particle shapes and uniform particle sizes. These assemblages are made from spherical, cylindrical and cubical particles, with an increasing order of particle angularity. Two types of loading paths in the hollow cylindrical apparatus are applied. One is the monotonic loading path with a range of fixed angles of major principal stress with respect to the horizontal bedding plan, used to investigate the anisotropy of materials. The other is the path of pure principal stress rotations, used to study the non-coaxiality. The experimental results indicate that these three materials exhibit a strong anisotropy and non-coaxiality. Their stress–strain responses are dependent on the orientation of major principal stress. The non-coaxiality is a function of stress ratio. In addition, there is a noticeable trend that these two characteristics are dependent on the angularity of particles. The more angular the particles are, the greater anisotropy and non-coaxiality take place
Microcantilever Studies of Angular Field Dependence of Vortex Dynamics in BSCCO
Using a nanogram-sized single crystal of BSCCO attached to a microcantilever
we demonstrate in a direct way that in magnetic fields nearly parallel to the
{\it ab} plane the magnetic field penetrates the sample in the form of
Josephson vortices rather than in the form of a tilted vortex lattice. We
further investigate the relation between the Josephson vortices and the pancake
vortices generated by the perpendicular field component.Comment: 5 pages, 8 figure
Controlling laser spectra in a phaseonium photonic crystal using maser
We study the control of quantum resonances in photonic crystals with
electromagnetically induced transparency driven by microwave field. In addition
to the control laser, the intensity and phase of the maser can alter the
transmission and reflection spectra in interesting ways, producing hyperfine
resonances through the combined effects of multiple scattering in the
superstructure.Comment: 7 pages, 4 figure
Anterior Hippocampus and Goal-Directed Spatial Decision Making
Contains fulltext :
115487.pdf (publisher's version ) (Open Access
Global Optimization by Energy Landscape Paving
We introduce a novel heuristic global optimization method, energy landscape
paving (ELP), which combines core ideas from energy surface deformation and
tabu search. In appropriate limits, ELP reduces to existing techniques. The
approach is very general and flexible and is illustrated here on two protein
folding problems. For these examples, the technique gives faster convergence to
the global minimum than previous approaches.Comment: to appear in Phys. Rev. Lett. (2002
Anisotropy of Vortex-Liquid and Vortex-Solid Phases in Single Crystals of BiSrCaCuO: Violation of the Scaling Law
The vortex-liquid and vortex-solid phases in single crystals of
BiSrCaCuO placed in tilted magnetic fields are studied
by in-plane resistivity measurements using the Corbino geometry to avoid
spurious surface barrier effects. It was found that the anisotropy of the
vortex-solid phase increases with temperature and exhibits a maximum at
. In contrast, the anisotropy of the vortex-liquid rises
monotonically across the whole measured temperature range. The observed
behavior is discussed in the context of dimensional crossover and thermal
fluctuations of vortices in the strongly layered system.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
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