Miracle-dz/UniFAR-FTUs huggingface dataset:
Performance analysis of an optical packet switch with optical buffers

This paper presents an approximate analysis of delay performance of a WD/SD optical packet/burst switch equipped with infinite optical buffers. By using M/G/1 model, we give the theoretical expression of delay performance of the switch fabric with/without assignment of priority class to service under fixed/variable packet length. Meanwhile, the results of numerical analysis are presented, too. According to these analyses, we give the following main conclusions: in the switch fabric with variable packet/burst length and no assignment of priority class to service, the mean packet/burst delay appears much smaller than that with fixed packet length; and in the switch fabric with assignment of three priority classes to service, the delay of two kinds of services with lower priority classes appears to bigger than that of service with no assignment of priority class.
Composite Likelihood Estimation for Multivariate Probit Latent Traits Models

Inference in generalized linear mixed models with multivariate random effects is often made cumbersome by the high-dimensional intractable integrals involved in the marginal likelihood. This article presents an inferential methodology based on the marginal composite likelihood approach for the probit latent traits models. This method belonging to the broad class of pseudo-likelihood involves marginal pairs probabilities of the responses which has analytical expression. The different results are illustrated with a simulation study and with an analysis of real data from health related quality of life.
Numerical Simulation of Melting and Resolidification of a Phase Change Material Around Two Cylindrical Heat Exchangers

A computational methodology is presented for solving natural convection dominated melting and resolidification of a phase change material around two horizontal cylindrical heat sources /sinks spaced vertically. A finite difference method with body-fitted coordinates is employed to handle the irregular boundaries, and a fixed grid enthalpy method is adopted for the phase change problem. Results show that the phase front during the melting and resolidification of the liquid from the upper cylinder is strongly affected by the surface temperature of the lower cylinder. Also, cyclic melting and freezing of the phase change material can result in complex shapes of the solid-liquid interfaces as well as in multiple phase fronts. The shapes of the melted and solidified regions depend on the imposed thermal boundary and the melting and freezing period.
High-frequency small-signal model of ferrite core inductors

A circuit model of ferrite core inductors is presented. The behavior of the model parameters versus frequency is considered. The total power loss in inductors consisting of the winding resistance loss and the core loss, is modeled by a frequency-dependent equivalent series resistance. The total inductance given by the sum of the main inductance and the leakage inductance is obtained as a function of frequency. In order to study the core equivalent resistance and main inductance versus frequency, the magnetic field distribution in the core is derived from Maxwell's equations for a long solenoid. The complex permeability and permittivity of the ferrite core are introduced in the electromagnetic field equations. Experimental results are also given.
Role of threading dislocation structure on the x‐ray diffraction peak widths in epitaxial GaN films

In this letter we demonstrate that the anomalously low (002) x‐ray rocking curve widths for epitaxial hexagonal GaN films on (001) sapphire are a result of a specific threading dislocation (TD) geometry. Epitaxial GaN films were grown on c‐plane sapphire by atmospheric pressure metalorganic chemical vapor deposition (MOCVD) in a horizontal flow reactor. Films were grown with (002) rocking curves (ω‐scans) widths as low as 40 arcsec and threading dislocation densities of ∼2×1010 cm−2. The threading dislocations in this film lie parallel to the [001] direction and within the limit of imaging statistics, all are pure edge with Burgers vectors parallel to the film/substrate interface. These TDs will not distort the (002) planes. However, distortion of asymmetric planes, such as (102), is predicted and confirmed in (102) rocking curve widths of 740 arcsec. These results are compared with films with (002) rocking curves of ∼270 arcsec and threading dislocation densities of ∼7×108 cm−2.
Comparison of some correlation array configurations for radio astronomy

The number of nonredundant baselines obtained from the T, Y, and ring array configurations are compared. For the same number of array elements, it is shown that the ring array has the largest number of baselines. The Y array has the second largest number of baselines; however, it also has more potential for adjustments and future growth.
More Exact Statements of Several Theorems in the Theory of Branching Processes

Theorems proved by A. N. Kolmogorov [2], A. M. Yaglom [3] and B. A. Sevastyanov [1] on regular branching processes with particles of one type homogeneous in time (parameter t being continuous) are made more exact. It is possible to do away with the requirement that the second and third factorial moments be finite in the integral limit theorems. For processes with $a = f'(1) \ne 0$, the form of limit theorems is the same as before. For processes with $a = 0$, it is necessary to require in addition that the generating function determining the branch process be properly variable in the sense of Karamata [4] with the index $\gamma = 1 + \alpha > 1$. In this case, a new class of distributions appears as the limit laws. The Laplace transforms for these distributions have a very simple form \[ \psi (s) = 1 - s(1 + s^\alpha )^{ - 1/ \alpha } ,\quad 0 < \alpha \leqq 1. \] The limit distributions of this class $S_\alpha (y)$ may be expressed by means of the densities of stable distributions $p(x,\alpha ,\beta )$ wi.
The photovoltaic response in poly(p-phenylene vinylene) thin-film devices

We report measurements of the photovoltaic effect in diode structures formed with thin films (100 nm) of the conjugated polymer poly(p-phenylene vinylene), PPV, sandwiched between electrodes of indium/tin oxide, ITO, and either aluminium, magnesium or calcium. Under illumination incident through the ITO contact, large open-circuit voltages were measured, which saturated at approximately 1.2 V for Al and Mg devices, and approximately 1.7 V for Ca devices. Quantum efficiencies (short-circuit current/incident photon flux) of order 1% were measured at low intensities (0.1 mW cm-2). The spectral response of the photocurrent demonstrates that photon absorption near the electron-collecting electrode optimizes the photocurrent, indicating that device performance is limited by low electron mobilities in the bulk PPV. The photocurrent exhibits a weak temperature dependence, with an activation energy that is a function of the electric field in the polymer. We have used these measurements to estimate an exciton binding energy in PPV of approximately 0.4 eV.
Distribution and kinematics of H I in the active elliptical galaxy NGC 1052

The H I distribution in the active elliptical galaxy NGC 1052 has been mapped at a resolution of 1 arcmin with the VLA. The H I structure is about three times the size of the optical galaxy and is roughly perpendicular to its major axis. The H I has a circular velocity of approx.200 km/s, roughly constant with radius; the mass of the galaxy is 1.5 x 10/sup 11/ M/sub sun/ at a radius of 16 kpc (D = 13.4 Mpc), and the mass to blue luminosity ratio at this radius is M/L/sub B/ approx.15 M/sub sun//L/sub sun/. H I absorption is seen against the central radio continuum source, at both the systemic velocity and at redshifted velocities. The gas in NGC 1052, as in other ellipticals, has a rotation axis that is not aligned with the stellar rotation axis (the difference is 63/sup 0/) and a mean specific angular momentum that is considerably larger than that of the stars. The H I distribution is unusually irregular. In the southwest region of the galaxy, the distribution shows what appears to be a tidal tail, suggesting that the H I may have been acquired about 10/sup 9/ years ago. The presencemore » of dust associated with the H I and the distribution and kinematics of the H I are consistent with capture of gas from a gas-rich dwarf or spiral. In the inner regions of the galaxy (r<5 kpc) the H I velocity field shows evidence of noncircular orbits and therefore possibly of a triaxial mass distribution for the galaxy. Alternatively the gas could be falling in toward the center. « less
Realization of noncausal 2-D systems based on a descriptor model

It is shown that a class of linear discrete noncausal two-dimensional systems can be represented by discrete descriptor systems whose coefficients are functions that admit Laurent series expansions on the unit circle in the complex plane. The basic idea is to obtain a conventional state-space realization with coefficient functions for causal and anticausal subsystems in one direction, and then view them as a descriptor system-a single entity. The resulting model is a 1-D descriptor system with coefficient functions defined on the unit circle in the complex plane. Some properties of this model concerning minimality are also investigated. >
Testing the distance-duality relation with data from galaxy clusters and type Ia supernovae

We test the distance-duality (DD) relation by combining the angular diameter distance D A provided by two galaxy cluster samples compiled by De Filippis et al. (the elliptical β model) and Bonamente et al. (the spherical β model), and the luminosity distance D L from Constitution and Union2 type Ia supernova (SNe Ia) datasets. To obtain D L associated with the observed D A at the same redshift, we smooth the noise of the SNe Ia in a model-independent way, obtain the evolutionary curve of D L and, finally, test the DD relation. We find that the elliptical β model, when compared with the SNe Ia from the Constitution compilation, is only consistent with the DD relation at the 3σ confidence level (CL), while the spherical β model is incompatible with the DD relation at the 3σ CL. For the Union2 compilation, the De Filippis and Bonamente samples are marginally compatible with the validity of the DD relation at the 1σ and 2σ CLs, respectively.
Mobility enhancement in conjugated polymer field-effect transistors through chain alignment in a liquid-crystalline phase

A method is demonstrated by which liquid-crystalline self-organization in rigid-rod nematic conjugated polymers can be used to control the microstructure of the active semiconducting layer in solution-processed polymer thin-film transistors (TFTs). Enhanced charge carrier mobilities of 0.01–0.02 cm2/V s and good operating stability have been achieved in polyfluorene copolymer TFTs by preparing the polymer in a nematic glassy state and by aligning the polymer chains parallel to the transport direction with the help of an alignment layer. Mobility anisotropies of 5–8 for current flow parallel and perpendicular to the alignment direction have been observed that are of the same order of magnitude as optical dichroic ratios.
Recurrence times and pointwise lower bounds in data compression

Let {X/sub t/} be a stationary ergodic process with values in a finite alphabet /spl Xscr/. For s/spl les/t let X/sub s//sup t/=(X/sub s/,.,X/sub t/). The first recurrence time of X/sup k/=(X/sub 0/,.,X/sub k-l/ is defined as the number of shifts back until X/sup k/ appears again. We give a simple proof using a lemma developed by Algoet and Cover (1985) to prove the asymptotic optimality of log-optimum selections in convex families.
The Image of Observables

This paper challenges a central tenet of constructive empiricism, namely that empirical adequacy has a privileged epistemic status. I argue that perceptions of observables are theory-wrought, and theory-wrought in the same ways as the observation sentences we use to describe those perceptions, van Fraassen can draw no privileged or fundamental distinction between what we observe and interpreting those observations through theory. Since empirical adequacy depends upon accurately describing what we observe, and we have no theory-independent reason to believe that what we ‘observe’ is a reflection of what is true, then empirical adequacy can inherit no special connection to what is real via what we observe. The epistemological significance of empirical adequacy is thereby reduced.
Maximum likelihood estimates via duality for log-convex models when cell probabilities are subject to convex constraints

The purpose of this article is to derive and illustrate a method for fitting models involving both convex and log-convex constraints on the probability vector(s) of a (product) multinomial distribution. We give a two-step algorithm to obtain maximum likelihood estimates of the probability vector(s) and show that it is guaranteed to converge to the true solution. Some examples are discussed which illustrate the procedure.
A Newton iterative mixed finite element method for stationary conduction–convection problems

In this article, a Newton iterative mixed finite element method is presented for solving the stationary conduction–convection problems in two dimensions. The stability and the errors generated by both partitioning the space and solving nonlinear equations are analysed, which show that our method is stable and has good precision. Finally, some numerical experiments are given to confirm its effect.
Velocity shear instability and plasma billows at the Earth's magnetic boundary

The Kelvin-Helmoltz instability (KH) with formation of vortices appears in a wide variety of terrestrial, interplanetary, and astrophysical contexts. We study a series of iterated rolled-up coherent plasma structures (15) that flow in the equatorial Earth's boundary layer (BL), observed on October 24, 2001. The data were recorded during a 1.5 hour-long Wind crossing of the BL at the dawn magnetospheric flank, tailward of the terminator (X≈−13 RE). The interplanetary magnetic field (IMF) was radially directed, almost antiparallel to the magnetosheath (MS) flow. This configuration is expected to be adverse to the KH instability because of the collinearity of field and flow, and the high compressibility of the MS. We analyze the BL stability with compressible MHD theory using continuous profiles for the physical quantities. Upstream, at near Earth sites, we input parameters derived from an exact MHD solution for collinear flows. Further downtail at Wind position we input measured parameters. The BL is found KH unstable in spite of unfavorable features of the external flow. On the experimental side, the passage of vortices is inferred from the presence of low density - hot plasma being accelerated to speeds higher than that of the contiguous MS. It is further supported by the peculiar correlation of relative motions (in the bulk velocity frame): cold-dense plasma drifts sunward, while hot-tenuous plasma moves tailward. This event differs from many other studies that reported BL vortices under strongly northward IMF orientations. This is a case of KH vortices observed under an almost radial IMF, with implicit significance for the more common Parker's spiral fields, and the problem of plasma entry in the magnetosphere.
Localized remeshing techniques for three‐dimensional metal forming simulations with linear tetrahedral elements

The localized remeshing technique for three‐dimensional metal forming simulations is proposed based on a mixed finite element formulation with linear tetrahedral elements in the present study. The numerical algorithm to generate linear tetrahedral elements is developed for finite element analyses using the advancing front technique with local optimization method which keeps the advancing fronts smooth. The surface mesh generation using mesh manipulations of the boundary elements of the old mesh system was made to improve mesh quality of the boundary surface elements, resulting in reduction of volume change in forming simulations. The mesh quality generated was compared with that obtained from the commercial CAD package for the complex geometry like lumbar. The simulation results of backward extrusion and bevel gear and spider forgings indicate that the currently developed simulation technique with the localized remeshing can be used effectively to simulate the three‐dimensional forming processes with a reduced computation time. Copyright © 2006 John Wiley & Sons, Ltd.
Proton and alpha particle fluxes in the solar wind: Results of a three‐fluid model

A three-fluid model for the solar wind, with continuity, momentum, and energy equations for the three species protons, alpha particles, and electrons, including electron heat conduction and a parameterized coronal heat source, is used to study the behavior of the resulting proton and alpha fluxes as a function of coronal energy input and the proton-to-alpha density ratio at the coronal base. While in model solutions without alpha particles the proton flux is a strongly increasing function of coronal temperature, quite opposite to the observed near constancy of the proton flux in the solar wind, solutions with alpha particle abundances of the order of a few percent at the coronal base have a reduced proton flux and much less variation of the proton flux. The mechanism by which the proton flux is reduced is a pileup of the alpha particle abundance in the region of the coronal temperature maximum and the increased frictional drag on the protons resulting therefrom. We find a range of model solutions in which the resulting proton flux is almost independent of coronal energy input or coronal temperature, and we conclude that proton-alpha friction and dynamic accumulation of alphas in the corona can provide an explanation for the near constancy of the proton flux which is observed in the solar wind.
Fiber laser pumped ultra-fast parametric amplifiers

We report on an optical parametric amplification system which is pumped and seeded by fiber generated laser radiation. Due to its low broadening threshold, high spatial beam quality and high stability, the fiber based broad bandwidth signal generation is a promising alternative to white light generation in bulky glass or sapphire plates. As pump source we propose the use of a high repetition rate ytterbium-doped fiber chirped pulse amplification system.
Optically-induced switching between mode-locked and unmode-locked continuous wave regimes of a femtosecond Cr4+:forsterite laser

The ability to control the temporal output from a femtosecond laser can enable the same laser to be used for multiple functions, for example, the laser used in an optical tweezers system could be used as a constant-intensity source to trap a biological cell and then be temporarily switched to mode-locked operation to effect photoporation. Here, we report the rapid switching of a Cr4+:forsterite laser between mode-locked and unmode-locked continuous wave (CW) regimes via the optical pumping of an intracavity SESAM element. Mode-locking of the laser was initiated by an intracavity quantum well (GaInAsN) SESAM having an anti-resonant design (ΔR~0.3%, λPL~1310nm) that yielded transform-limited 89fs pulses centered around 1296nm with a repetition rate of 162MHz at an average power of 64mW. Upon excitation of the SESAM with 600mW of extra-cavity power from an 808nm semiconductor diode laser, switching could be induced between the unmode-locked and mode-locked regimes. Transitions free of Q-switching or relaxation oscillations were observed with <200μs switching times for both for the initiation and cessation of mode-locking. Periods of mode-locked operation of custom duration could be produced by appropriate control of the SESAM pump diode enabling the generation of bursts of pulses as short as 400μs. Switching was confirmed to originate from local pump-induced heating of the SESAM by observing the laser going through identical regime switching when the chip temperature of the 'unpumped' SESAM was raised by ~20°C.
Weyl geometry, anti-de Sitter space, and Φ 4 -theory

We study the Gaussian approximation to the quantum ﬂuctuations of the metric of the four-dimensional anti-de Sitter spacetime. The associated massless scalar ﬁeld has a quartic self-interaction, for which we construct the generating functional of the n -point correlation functions. The concomitant infrared divergence is cured by a mass renormalization provided by the cosmological constant, which is also responsible for the renormalization of the coupling constant of the ﬁeld theory.
Existence and multiplicity of weak solutions for nonuniformly elliptic equations with nonstandard growth condition

We discuss the problem – div(a(x, ∇u)) = m(x)|u| r(x)−2 u + n(x)|u| s(x)−2 u in Ω, where Ω is a bounded domain with smooth boundary in ℝ N (N ≥ 2), and div(a(x, ∇u)) is a p(x)-Laplace type operator with 1 < r(x) < p(x) < s(x). We show the existence of infinitely many nontrivial weak solutions in . Our approach relies on the theory of the variable exponent Lebesgue and Sobolev spaces combined with adequate variational methods and a variation of the Mountain Pass lemma and critical point theory.
Scattering cross sections for random rough surfaces: Full wave analysis

The full wave approach developed earlier to evaluate the radiation fields scattered by deterministic two dimensionally rough surfaces is used here to determine the scattering cross sections for random rough surfaces. The medium below the irregular boundary is characterized by complex permittivity and permeability. For slightly rough surfaces, the full wave solutions for the incoherent scattered fields are shown to be in agreement with the perturbation solution. However, when the major contributions to the scattered fields come from the region of the rough surface around the stationary phase (specular) points, the full wave solutions are in agreement with the physical optics solutions. Thus the full wave solutions which reduce to the perturbation, the physical optics, and the geometrical optics approximations in special cases precisely determine the limitations of these approximations and reconcile the differences between them. The full wave solutions satisfy duality, reciprocity, and realizability relations in electromagnetic theory, and they are invariant under coordinate transformations.
A novel low-altitude reconnaissance strategy for smart UAVs: active perception and chaotic navigation

In this article, an innovative approach is proposed for multi-sensory integration applied in autonomous navigation for smart low-altitude reconnaissance unmanned aerial vehicles (UAVs). The new UAV navigation technique exploits the use of a pan—tilt-based visual sensing system, which is able to implement the strategy of active perception, increasing the richness of the information acquired from the environments. In addition, based on the information theory, a significant optimality criterion, so-called observation entropy, is represented to determine which set of landmarks should be adopted as the optimal set of information source. Moreover, a chaotic reaction system, inspired by the olfactory bulb neural activity observed in rabbits subject to external stimuli, is considered to build the perception-motion dynamics loop. The loop can be used to adaptively guide the UAV actions not only when it perceives a set of landmarks, but also when the UAV is in environments without enough landmarks. Finally, the sim.