23,780 research outputs found
Dependable Digitally-Assisted Mixed-Signal IPs Based on Integrated Self-Test & Self-Calibration
Heterogeneous SoC devices, including sensors, analogue and mixed-signal front-end circuits and the availability of massive digital processing capability, are being increasingly used in safety-critical applications like in the automotive, medical, and the security arena. Already a significant amount of attention has been paid in literature with respect to the dependability of the digital parts in heterogeneous SoCs. This is in contrast to especially the sensors and front-end mixed-signal electronics; these are however particular sensitive to external influences over time and hence determining their dependability. This paper provides an integrated SoC/IP approach to enhance the dependability. It will give an example of a digitally-assisted mixed-signal front-end IP which is being evaluated under its mission profile of an automotive tyre pressure monitoring system. It will be shown how internal monitoring and digitally-controlled adaptation by using embedded processors can help in terms of improving the dependability of this mixed-signal part under harsh conditions for a long time
Some Double Sums Involving Ratios of Binomial Coefficients Arising From Urn Models
In this paper we discuss a class of double sums involving ratios of binomial
coefficients. The sums are of the form where are
functions of . Such sums appear in the analyses of the Mabinogion urn and
the Ehrenfest urn in probability. Using hypergeometric functions, we are able
to simplify these sums, and in some cases express them in terms of the harmonic
numbers
Calculation of the quark condensate through Schwinger-Dyson equation
In this letter, we clarify the algebra expression for calculating the quark
condensate based on the non-perturbative quark propagator calculated through
Schwinger-Dyson equation. The quark condensates, which characterize the low
energy QCD vacuum, should not get a divergent quantity at large energy scale;
the re-normalization group evolution behaviour at large energy scale therefore
should be interpreted as "smeared collective effects" for it contains both
perturbative and non-perturbative parts.
We prefer the integral expression and get a quantity which is both convergent
and scale dependent.Comment: 6 page
Counting points on varieties over finite fields of small characteristic
We present a deterministic polynomial time algorithm for computing the zeta
function of an arbitrary variety of fixed dimension over a finite field of
small characteristic. One consequence of this result is an efficient method for
computing the order of the group of rational points on the Jacobian of a smooth
geometrically connected projective curve over a finite field of small
characteristic.Comment: To appear in: "Algorithmic number theory: lattices, number fields,
curves and cryptography", J.P. Buhler and P. Stevenhagen (ed.), Math. Sci.
Res. Inst. Publ. 44. (Submitted July 2001; Accepted October 2002.
Integrals of and from Lattice Sums
We give closed form evaluations for many families of integrals, whose
integrands contain algebraic functions of the complete elliptic integrals
and . Our methods exploit the rich structures connecting complete elliptic
integrals, Jacobi theta functions, lattice sums, and Eisenstein series. Various
examples are given, and along the way new (including 10-dimensional) lattice
sum evaluations are produced
Holonomic alchemy and series for
We adopt the "translation" as well as other techniques to express several
identities conjectured by Z.-W. Sun in arXiv:1102.5649v47 by means of known
formulas for involving Domb and other Ap\'ery-like sequences.Comment: 23 page
Propagation of Solar Energetic Particles in Three-dimensional Interplanetary Magnetic Fields: Radial Dependence of Peak Intensities
A functional form I_{max}(R)=kR^{-\alpha}, where R is the radial distance of
spacecraft, was usually used to model the radial dependence of peak intensities
I_{max}(R) of solar energetic particles (SEPs). In this work, the
five-dimensional Fokker-Planck transport equation incorporating perpendicular
diffusion is numerically solved to investigate the radial dependence of SEP
peak intensities. We consider two different scenarios for the distribution of
spacecraft fleet: (1) along the radial direction line, (2) along the Parker
magnetic field line. We find that the index \alpha in the above expression
varies in a wide range, primarily depending on the properties (e.g., location,
coverage) of SEP sources and on the longitudinal/latitudinal separations
between the sources and the magnetic footpoints of the observers. Particularly,
the situation that whether the magnetic footpoint of the observer is located
inside or outside of the SEP source is a crucial factor determining the values
of index \alpha. A two-phase phenomenon is found in the radial dependence of
peak intensities. The "position" of the breakpoint (transition point/critical
point) is determined by the magnetic connection status of the observers. This
finding suggests that a very careful examination of magnetic connection between
SEP source and each spacecraft should be taken in the observational studies. We
obtain a lower limit of R^{-1.7\pm0.1} for empirically modelling the radial
dependence of SEP peak intensities. Our findings in this work can be used to
explain the majority of the previous multispacecraft survey results, and
especially to reconcile the different/conflicting empirical values of index
\alpha in the literature.Comment: Published in Ap
Spinon walk in quantum spin ice
We study a minimal model for the dynamics of spinons in quantum spin ice. The
model captures the essential strong coupling between the spinon and the
disordered background spins. We demonstrate that the spinon motion can be
mapped to a random walk with an entropy-induced memory in imaginary time. Our
numerical simulation of the spinon walk indicates that the spinon propagates as
a massive quasiparticle at low energy despite its strong coupling to the spin
background at the microscopic energy scale. We discuss the experimental
implications of our findings.Comment: 12 pages, 10 figure
Cleavage Tendency of Anisotropic Two Dimensional Materials: ReX2 (X=S, Se) and WTe2
With unique distorted 1T structure and the associated in-plane anisotropic
properties, mono- and few-layer ReX2 (X=S, Se) have recently attracted
particular interest. Based on experiment and first-principles calculations, we
investigate the fracture behavior of ReX2. We find that the cleaved edges of
ReX2 flakes usually form an angle of ~120{\deg} or ~60{\deg}. In order to
understand such phenomenon, we perform comprehensive investigations on the
uniaxial tensile stress-strain relation of monolayer and multi-layer ReX2
sheets. Our numerical calculation shows that the particular cleaved edges of
ReX2 flakes are caused by unique anisotropic ultimate tensile strengths and
critical strains. We also calculate the stress-strain relation of WTe2, which
explains why their cleaved edges are not corresponding to the principle axes.
Our proposed mechanism about the fracture angle has also been supported by the
calculated cleavage energies and surface energies for different edge surfaces
Nonlinear ER effects in an ac applied field
The electric field used in most electrorheological (ER) experiments is
usually quite high, and nonlinear ER effects have been theoretically predicted
and experimentally measured recently. A direct method of measuring the
nonlinear ER effects is to examine the frequency dependence of the same
effects. For a sinusoidal applied field, we calculate the ac response which
generally includes higher harmonics. In is work, we develop a multiple image
formula, and calculate the total dipole moments of a pair of dielectric
spheres, embedded in a nonlinear host. The higher harmonics due to the
nonlinearity are calculated systematically.Comment: Presented at Conference on Computational Physics (CCP2000), held at
Gold Coast, Australia from 3-8, December 200
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