105,525 research outputs found
Web-based haptic applications for blind people to create virtual graphs
Haptic technology has great potentials in many applications. This paper introduces our work on delivery haptic information via the Web. A multimodal tool has been developed to allow blind people to create virtual graphs independently. Multimodal interactions in the process of graph creation and exploration are provided by using a low-cost haptic device, the Logitech WingMan Force Feedback Mouse, and Web audio. The Web-based tool also provides blind people with the convenience of receiving information at home. In this paper, we present the development of the tool and evaluation results. Discussions on the issues related to the design of similar Web-based haptic applications are also given
Comment on "Spectroscopic Evidence for Multiple Order Parameter Components in the Heavy Fermion Superconductor CeCoIn"
Recently, Rourke et al. reported point-contact spectroscopy results on the
heavy-fermion superconductor CeCoIn [1]. They obtained conductance spectra
on the c-axis surfaces of CeCoIn single crystals. Their major claims are
two-fold: CeCoIn has i) d-wave pairing symmetry and ii) two coexisting
order parameter components. In this Comment, we show that these claims are not
warranted by the data presented. [1] Rourke et al., Phys. Rev. Lett. 94, 107005
(2005).Comment: accepted for publication in Phys. Rev. Lett., final for
Localization of electric field distribution in graded core-shell metamaterials
The local electric field distribution has been investigated in a core-shell
cylindrical metamaterial structure under the illumination of a uniform incident
optical field. The structure consists of a homogeneous dielectric core, a shell
of graded metal-dielectric metamaterial, embedded in a uniform matrix. In the
quasi-static limit, the permittivity of the metamaterial is given by the graded
Drude model. The local electric potentials and hence the electric fields have
been derived exactly and analytically in terms of hyper-geometric functions.
Our results showed that the peak of the electric field inside the cylindrical
shell can be confined in a desired position by varying the frequency of the
optical field and the parameters of the graded profiles. Thus, by fabricating
graded metamaterials, it is possible to control electric field distribution
spatially. We offer an intuitive explanation for the gradation-controlled
electric field distribution
On the efficiency of estimating penetrating rank on large graphs
P-Rank (Penetrating Rank) has been suggested as a useful measure of structural similarity that takes account of both incoming and outgoing edges in ubiquitous networks. Existing work often utilizes memoization to compute P-Rank similarity in an iterative fashion, which requires cubic time in the worst case. Besides, previous methods mainly focus on the deterministic computation of P-Rank, but lack the probabilistic framework that scales well for large graphs. In this paper, we propose two efficient algorithms for computing P-Rank on large graphs. The first observation is that a large body of objects in a real graph usually share similar neighborhood structures. By merging such objects with an explicit low-rank factorization, we devise a deterministic algorithm to compute P-Rank in quadratic time. The second observation is that by converting the iterative form of P-Rank into a matrix power series form, we can leverage the random sampling approach to probabilistically compute P-Rank in linear time with provable accuracy guarantees. The empirical results on both real and synthetic datasets show that our approaches achieve high time efficiency with controlled error and outperform the baseline algorithms by at least one order of magnitude
Dielectric behavior of oblate spheroidal particles: Application to erythrocytes suspensions
We have investigated the effect of particle shape on the eletrorotation (ER)
spectrum of living cells suspensions. In particular, we consider coated oblate
spheroidal particles and present a theoretical study of ER based on the
spectral representation theory. Analytic expressions for the characteristic
frequency as well as the dispersion strength can be obtained, thus simplifying
the fitting of experimental data on oblate spheroidal cells that abound in the
literature. From the theoretical analysis, we find that the cell shape, coating
as well as material parameters can change the ER spectrum. We demonstrate good
agreement between our theoretical predictions and experimental data on human
erthrocytes suspensions.Comment: RevTex; 5 eps figure
Many-body dipole-induced dipole model for electrorheological fluids
Theoretical investigations on electrorheological (ER) fluids usually rely on
computer simulations. An initial approach for these studies would be the
point-dipole (PD) approximation, which is known to err considerably when the
particles approach and finally touch due to many-body and multipolar
interactions. Thus various work attempted to go beyond the PD model. Being
beyond the PD model, previous attempts have been restricted to either
local-field effects only or multipolar effects only, but not both. For
instance, we recently proposed a dipole-induced-dipole (DID) model which is
shown to be both more accurate than the PD model and easy to use. This work is
necessary because the many-body (local-field) effect is included to put forth
the many-body DID model. The results show that the multipolar interactions can
indeed be dominant over the dipole interaction, while the local-field effect
may yield an important correction.Comment: RevTeX, 3 eps figure
Nonlinear ac responses of electro-magnetorheological fluids
We apply a Langevin model to investigate the nonlinear ac responses of
electro-magnetorheological (ERMR) fluids under the application of two crossed
dc magnetic (z axis) and electric (x axis) fields and a probing ac sinusoidal
magnetic field. We focus on the influence of the magnetic fields which can
yield nonlinear behaviors inside the system due to the particles with a
permanent magnetic dipole moment.
Based on a perturbation approach, we extract the harmonics of the magnetic
field and orientational magnetization analytically. To this end, we find that
the harmonics are sensitive to the degree of anisotropy of the structure as
well as the field frequency. Thus, it is possible to real-time monitor the
structure transformation of ERMR fluids by detecting the nonlinear ac
responses.Comment: 21 pages, 4 figure
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