128,770 research outputs found
Recursive Integral Method with Cayley Transformation
Recently, a non-classical eigenvalue solver, called RIM, was proposed to
compute (all) eigenvalues in a region on the complex plane. Without solving any
eigenvalue problem, it tests if a region contains eigenvalues using an
approximate spectral projection. Regions that contain eigenvalues are
subdivided and tested recursively until eigenvalues are isolated with a
specified precision. This makes RIM an eigensolver distinct from all existing
methods. Furthermore, it requires no a priori spectral information. In this
paper, we propose an improved version of {\bf RIM} for non-Hermitian eigenvalue
problems. Using Cayley transformation and Arnoldi's method, the computation
cost is reduced significantly. Effectiveness and efficiency of the new method
are demonstrated by numerical examples and compared with 'eigs' in Matlab
Pair Interaction Potentials of Colloids by Extrapolation of Confocal Microscopy Measurements of Collective Structure
A method for measuring the pair interaction potential between colloidal
particles by extrapolation measurement of collective structure to infinite
dilution is presented and explored using simulation and experiment. The method
is particularly well suited to systems in which the colloid is fluorescent and
refractive index matched with the solvent. The method involves characterizing
the potential of mean force between colloidal particles in suspension by
measurement of the radial distribution function using 3D direct visualization.
The potentials of mean force are extrapolated to infinite dilution to yield an
estimate of the pair interaction potential, . We use Monte Carlo (MC)
simulation to test and establish our methodology as well as to explore the
effects of polydispersity on the accuracy. We use poly-12-hydroxystearic
acid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in
the solvent dioctyl phthalate (DOP) to test the method and assess its accuracy
for three different repulsive systems for which the range has been manipulated
by addition of electrolyte.Comment: 35 pages, 14 figure
Quantum decoherence of excitons in a leaky cavity with quasimode
For the excitons in the quantum well placed within a leaky cavity, the
quantum decoherence of a mesoscopically superposed states is investigated based
on the factorization theory for quantum dissipation. It is found that the
coherence of the exciton superposition states will decrease in an oscillating
form when the cavity field interacting with the exciton is of the form of
quasimode. The effect of the thermal cavity fields on the quantum decoherence
of the superposition states of the exciton is studied and it is observed that
the higher the temperature of the environment is, the shorter the decoherence
characteristic time is.Comment: 1 figure, 7 page
Dynamic delamination crack propagation in a graphite/epoxy laminate
Dynamic delamination crack propagation in a (90/0) 5s Graphite/Epoxy laminate with an embedded interfacial crack was investigated experimentally using high speed photography. The dynamic motion was produced by impacting the beamlike laminate specimen with a silicon rubber ball. The threshold impact velocities required to initiate dynamic crack propagation in laminates with varying initial crack positions were determined. The crack propagation speeds were estimated from the photographs. Results show that the through the thickness position of the embedded crack can significantly affect the dominant mechanism and the threshold impact velocity for the onset of crack movement. If the initial delamination is placed near the top of bottom surface of the laminate, local buckling of the delaminated plies may cause instability of the crack. If the initial delamination lies on the midplane, local buckling does not occur and the initiation of crack propagation appears to be dominated by Mode II fracture. The crack propagation and arrest observed was seen to be affected by wave motion within the delamination region
Anomalous Magnetic and Thermal Behavior in Some RMn2O5 Oxides
The RMn2O5 (R=Pr, Nd, Sm, and Eu) oxides showing magnetoelectric (ME)
behavior have been prepared in polycrystalline form by a standard citrate
route. The lattice parameters, obtained from the powder XRD analysis, follow
the rare-earth contraction indicating the trivalent character of the R ions.
Cusp-like anomalies in the magnetic susceptibility curve and sharp peaks in the
specific heat were reported at the corresponding temperatures in RMn2O5 (R=Pr,
Nd, Sm, and Eu) indicating the magnetic or electric ordering transitions.Comment: 2 pages, 1 table, 3 figures, will be published in the Proceedings of
the 24th International Conference on Low Temperature Physic
Antenna Miniaturization Based on Supperscattering Effect
Antennas are essential components of all existing radio equipments. The miniaturization of antenna is a key issue of antenna technology. Based on supperscattering effect, we found that when a small horn antenna is located inside of a dielectric core and covered with a complementary layer, its far field radiation pattern will be equivalent to a large horn antenna. The complementary layer with only axial parameters varying with radius is obtained using coordinate transformation theory. Besides, the influence of loss and perturbations of parameters on supperscattering effect is also investigated. Results show that the device is robust against the perturbation in the axial material parameters when the refractive index is kept invariant. Full-wave simulations based on finite element method are performed to validate the design
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