Miracle-dz/UniFAR-FTUs huggingface dataset:
Development of low-flux SWIR radio-imaging systems to study nightglow emission

In this paper, we report the development of low flux short wavelength infrared radio-imaging systems to study the radiance due to nightglow emission. This radiation is mainly due to the desexcitation of hydroxyl molecules in the upper atmosphere. It is present in the visible range and reaches its maximum value (at ground level) in the short wavelength infrared band between 1.4 and 1. 8μm. The nightglow may be an interesting additional light source for night vision systems in moonless or cloudy sky conditions. In this paper, we describe the experimental setup and present first results of the measurement campaigns that we performed at the Observatoire de Haute-Provence in France and at the European Southern Observatory site of La Silla in Chile.
Group-index birefringence and loss measurements in silicon-on-insulator photonic wire waveguides

Group-index birefringence in silicon-on-insulator photonic wire waveguides is determined through a polarization beating technique and a Fabry-Perot resonance method. A large group-index birefringence, up to 0.67, is obtained as a result of the structural asymmetry and high field confinement of our waveguides. The group index and linear propagation loss are also determined. In particular, the group index is found to be as large as 4.45 due to the significant change in the effective mode index of the waveguide as a function of the wavelength. The effects of structure size on the measured losses and group indices are analyzed. Our experimental results are in good agreement with our simulations, and the method employed is found to be effective in analyzing the linear properties of submicrometer optical waveguide structures.
Entropy production in polarizable bodies with internal variables

Abstract A model of polarizable media investigated by Maugin and coworkers is considered as the domain of application of a recent method for the geometrization of the thermo-elasticity of continua with internal variables. The polarization together with its space gradient are assumed as state variables expressed in terms of internal variables evolving according to a relaxation law driven by external and internal electric fields. The entropy productions in Clausius-Duhem inequalities are calculated explicitly.
Calculations of the electronic structure of strained InAs quantum dots in InP

We have calculated the electronic structure of InAs quantum dots embedded in InP as a function of size, using strain dependent eight-band k⋅p theory in the envelope function approximation. A realistic three-dimensional shape was used for the simulations and the piezoelectric polarization of the system was included. In order to avoid spurious solutions, an extra term was added to the Hamiltonian. Polarization dependent dipole matrix elements were calculated as well as the exciton binding energies. A comparison between measurements and calculated transition energies shows good agreement.
Boundary integral equations for two‐dimensional low Reynolds number flow past a porous body

In this paper we use the method of matched asymptotic expansions in order to study the two‐dimensional steady flow of a viscous incompressible fluid at low Reynolds number past a porous body of arbitrary shape. One assumes that the flow inside the porous body is described by the Brinkman model, i.e. by the continuity and Brinkman equations, and that the velocity and boundary traction fields are continuous across the interface between the fluid and porous media. By considering some indirect boundary integral representations, the inner problems are reduced to uniquely solvable systems of Fredholm integral equations of the second kind in some Sobolev or Hölder spaces, while the outer problems are solved by using the singularity method. It is shown that the force exerted by the exterior flow on the porous body admits an asymptotic expansion with respect to low Reynolds number, whose terms depend on the solutions of the abovementioned system of boundary integral equations. In addition, the case of small permeability of the porous body is also treated. Copyright © 2008 John Wiley & Sons, Ltd.
Spectroscopic Observations of the Star Formation Activities in the Central Regions of Early-Type Spiral Galaxies

We study the characteristics of central star-forming regions of early-type spiral galaxies by optical spectroscopic observations. The sample consists of 13 galaxies which have ratios of far-infrared (FIR) to optical B-band luminosity, log(LFIR/LB), larger than the average of this type, -0.5. Strong line emissions are detected around the nucleus, and the line ratios of most regions are H II region-like, except for a few shocked regions. There is no low-ionization nuclear emission-line region (LINER). The [N II] and [S II] lines are somewhat enhanced, compared to the disk H II regions, but the enhancements cannot be attributed to hidden active galactic nuclei (AGNs) and the shock excitation. The median extinction derived from the Hα/Hβ intensity ratio is 1.0 mag in AV, and the median SFR of our sample galaxies, corrected for extinction, is estimated to be 2 M⊙ yr-1. Both values are comparable to those of late-type spiral galaxies. We find a correlation that the radii of the central star-forming regions tend to become larger with the turn-over radii of the rotation curves.
Initiation of Deep Convection along Boundary Layer Convergence Lines in a Semitropical Environment

Abstract The initiation of deep convection through forcing along boundary layer convergence lines is examined using observations from the Convection and Precipitation/Electrification Experiment conducted in east-central Florida during the summer of 1991. The study is concerned with the evolution and interaction of two converging air masses that were initially separated by an intervening boundary layer characterized by neutral stability and horizontal convective rolls. As anticipated, major thunderstorm erupt when the east coast breeze eventually collides with thunderstorm outflows from the west, but unexpected convection takes place prior to their merger along a well-defined confluence zone associated with a persistent quasi-stationary roll vortex signature. Analyses using wavelet transforms confirm that linear boundary layer reflectivity features are strongly correlated with radial convergence associated with roll vortices. In this study, complementary interactions between roll vortex convergence lines a.
A REINVESTIGATION OF LAMINAR CHANNEL FLOW PASSING OVER POROUS BED

ABSTRACT Laminar shear flows in channels with porous media bed are reinvestigated in the present study. The problem is similar to multiple-layered Poiseuille flow; the upper layer is homogeneous fluid, while the lower layer is rigid porous media flow. The conventional Navier-Stokes equation simplified by the fully developed channel flow condition is used to deal with the upper layer flow. The governing equation of laminar porous media flow derived in Song [7] is simplified and applied to the porous media bed. The analytical solution obtained in this study not only provides more reasonable fluid velocity inside the porous media bed than the one Darcy's law gives, but is also capable of clearly describing the partial-slip boundary condition given in Beavers and Joseph [1]. We further find that when the thinickness of the porous media bed divided by the square root of specific permeability approaches infinity, the nondimensional parameter α in the partial-slip boundary condition is only a function of porosit.
Mémoire sur une classe particulière d'équations résolubles algébriquement.

JU est vrai que les oquations algebriques ne sont pas resolubles genoralementj mais il y en a une classe particuliere de tous les degres dont la rosolution algebrique est possible. Teiles sont p. ex. les equations de la forme x—1=0. La r solution de ces equations est fondoe sur certaines relations qui existent entre les racines. J'ai essaye a goneraliser cette remarque en supposant que deux racines d'une equation donnee soient tellement liees entre elles, qu'on puisse exprimer rationellement Fune par Tautre, et j'ai trouvo, qu'une teile Equation peut toujours ^tre r solue a Taide d'un certain nombre d'equations moins elevees. II y a meme des cas o Γόη peut resoudre a lg^br iquement l'equatien donnee eile meme. Cela arrive p. ex. toutes les fois que, l'equation donnee otant irreductible, son degre est un nombre premier. La m£me chose a lieu encere si toutes les racines d'une oquation peuvent 3tre exprimoes par χ, θχ, Θχ, θ*χ, . θ-χ, o θχ=ζχ, f)x otant une fonction rationnelle de x, et cc, x, f . des fonctions de la m6me forme de θχ, prise deux fois, trois fois, etc. . xn l . L'equation τ-= 0, si n est un nombre premier, est dans ce ' CC ~~~ A
Comparison of Turbine Tip Leakage Flow for Flat Tip and Squealer Tip Geometries at High-Speed Conditions

The tip leakage flow characteristics for flat and squealer turbine tip geometries are studied in the von Karman Institute Isentropic Light Piston Compression Tube facility, CT-2, at different Reynolds and Mach number conditions for a fixed value of the tip gap in a nonrotating, linear cascade arrangement. To the best knowledge of the authors, these are among the very few high-speed tip flow data for the flat tip and squealer tip geometries. Oil flow visualizations and static pressure measurements on the blade tip, blade surface, and corresponding endwall provide insight to the structure of the two different tip flows. Aerodynamic losses are measured for the different tip arrangements, also. The squealer tip provides a significant decrease in velocity through the tip gap with respect to the flat tip blade. For the flat tip, an increase in Reynolds number causes an increase in tip velocity levels, but the squealer tip is relatively insensitive to changes in Reynolds number.
Suppression and Dissipation of Weak Tornadoes in Metropolitan Areas: A Case Study of Greater London

Abstract Examination of the distribution of property-damaging tornadoes which have occurred in and around Greater London since 1830 reveals that the inner parts of the metropolis have experienced relatively few tornadoes during the past 150 years compared with the outer areas of the metropolis and the surrounding countryside. The authors suggest that urban factors such as the increased surface roughness of the urban fabric and the urban heat island suppress the formation of tornadoes from some storms which would otherwise have produced tornadoes and to cause the dissipation of some tornadoes already formed outside the urban area when they reach the outer suburbs. These effects appear to be restricted to tornadoes of weak intensity because the small-scale influence of urban areas may be negligible for a large-scale synoptic and meteorological situation producing moderate or severe tornadoes, as evident during the 3 April 1974 tornado outbreak in the United States.
FLUIDS ANALYSIS OF THE THERMAL MICROPUMP FOR A FUEL ATOMIZER

This article applies the thermal micropump to the injector of the fuel atomizer of a motorbike and makes a fluid behavior analysis by means of computational fluid dynamics, with water and Stoddard solvent as working liquids. The purpose is to discuss the speed, shape, and path of the droplets, the internal flow field, and work liquid replenishment after the injection of the micropump under two different situations: when the external air is at the condition of rest, and when it flows at a speed of 15.0 m/s. This micropump for a fuel atomizer consists of 50 independent micropumps, with orifices of 50 μm diameter and a working frequency of 5 kHz. The results of the study indicate that Stoddard solvent, with its lower density, is subject to the influence of external flowing air, which will result in the breaking of the droplets and the offset of the flying path. The flow of external air not only changes the shape of the liquid droplets and the flying path, but also delays the starting time of working liquid replenishment. The time gap between the initiations of replenishment in different working liquids is decreased and the remaining air pores in the cavity of the micropump become fewer under the effect of air cross-flow.
Propagation of Rayleigh-type surface waves in a transversely isotropic piezoelectric layer on a piezomagnetic half-space

Propagation of Rayleigh-type surface waves in a piezoelectric-piezomagnetic layered half-space is investigated. The materials are assumed to be transversely isotropic crystals. The dispersion relations have been numerically derived and computed by considering the coupling piezoelectric and piezomagnetic behaviors. The phase velocities are obtained for four kinds of electric-magnetic boundary conditions at the free surface. The variations of mechanical displacements, electric and magnetic potentials along the thickness direction of the layer are obtained. The effects of different electric-magnetic boundary conditions on the phase velocity and mode shapes of displacements, electric and magnetic potentials have been discussed. The results show that the lowest mode is Rayleigh mode and that the phase velocities of the higher modes tend to the shear wave velocity of the piezoelectric layer as the frequency increases. The electric boundary conditions dominate the phase velocity. The magnetic boundary conditions.
Experimental Study on Liquid Spread and Maldistribution in the Trickle Bed Reactor Using Electrical Resistance Tomography

A lab scale trickle bed reactor (TBR) has been employed to investigate the effect of particles and liquid flow rate on the phase distribution in TBR. The TBR module, made up of 100 mm inner diameter acrylic column, was randomly packed with inert porous alumina particles of different average diameters that are used in actual reactor. Water was fed from the top of the column by “point feed” and “homogenous feed” strategies and cross-sectional liquid distributions were captured at several axial positions from the top to the bottom of the column by employing electrical resistance tomography (ERT) technique. ERT is a non-invasive cross-sectional imaging technique that provides the cross-sectional conductivity distribution by injecting current and measuring voltages between the several electrodes (16 electrodes in our case) that are attached around the column. The cross-sectional conductivity thus obtained represents the liquid hold up and degree of maldistribution of the liquid. In the experiment, quicker and more homogenous distribution of liquid was obtained for the particles with smaller diameters. That is due to capillary force that cancels the randomness of packing. Electrical resistance tomography seems to be reliable non-invasive instrumentation technique to optimize the design and operations of the trickle bed reactors.
VIBRATIONS OF PARTIALLY FILLED CYLINDRICAL TANKS WITH RING-STIFFENERS AND FLEXIBLE BOTTOM

Abstract The dynamics of a tank partially filled with a liquid having a free surface is investigated. In the analysis, the effect of free surface waves is taken into account, so that both bulging and sloshing modes are studied. The structure is completely flexible, and is composed of a vertically standing circular cylindrical shell, with ring-stiffeners, and a flexible bottom that consists of a circular plate generally resting on an elastic Winkler foundation. The plate edge is joined to the shell by coupling rotational springs distributed around the edge. The interaction between the plate and the shell via the fluid is included. Application to the particular cases of (i) a flexible shell with a rigid bottom and (ii) a flexible bottom plate with a rigid cylinder are also presented, as well as a comparison with approximate theories. Ring-stiffeners on the shell are also considered in order to investigate their influence on the modal behaviour of the tank. Solution of this problem is achieved via the method of artificial springs within the framework of the Rayleigh–Ritz theory, while considering strong fluid–structure interaction.
Regularized minimum I-divergence methods for the inverse blackbody radiation problem

This paper proposes iterative methods for estimating the area temperature distribution of a blackbody from its total radiated power spectrum measurements. This is called the inverse blackbody radiation problem. This problem is inherently ill-posed due to the characteristics of the kernel in the underlying integral equation given by Planck's law. The functions involved in the problem are all non-negative. Csiszár's I-divergence is an information-theoretic discrepancy measure between two non-negative functions. We derive iterative methods for minimizing Csiszár's I-divergence between the measured power spectrum and the power spectrum arising from the estimate according to the integral equation. Due to the ill-posedness of the problem, unconstrained algorithms often produce poor estimates, especially when the measurements are corrupted by noise. To alleviate this difficulty, we apply regularization methods to our algorithms. Penalties based on Shannon's entropy, the L1-norm and Good's roughness are chosen to suppress the undesirable artefacts. When a penalty is applied, the pertinent optimization that needs to be performed at each iteration is no longer trivial. In particular, Good's roughness causes couplings between estimate components. To handle this issue, we adapt Green's one-step-late method. This choice is based on the important fact that our minimum I-divergence algorithms can be interpreted as asymptotic forms of certain expectation-maximization algorithms. The effectiveness of our methods is illustrated via various numerical experiments.
On the preceding paper “A Legendre polynomial integral” by James L. Blue

The modified moments of the distribution do(x) = xa In (1 /x) dx on [ 0, 1 ], with respect to the shifted Legendre polynomials, are explicitly evaluated. The result in the theorem of Section 2 of [1] can be generalized as follows: Let vn(a)=S10xaln(l/x)P*(x)dx, ot>-l, « = 0,1,2,. , where P*(x) = P„(2x 1) is the shifted Legendre polynomial of degree n. Then (1) "„(«) = / ,N«-m mr(n m l)\ . (-1) -*■-", a = m<n,m>0an integer, (n + m + l)\ 1 . A / 1 1 \/ A OL+l -k otherwise. _LJ_L+ /_J_i_\? A a+lja+1 ^yot + l+k a + l-k/L^ ! OL+l+k The result in [1] is the case a = 0 of (1). For the proof, we note that «'„(a) = -2-<°+1>£i(l +t)aln(K(l + t))Pn(t)dt (2) = -2-<a + 1> Urn {£(1 + t)a ln(l + t)Pv(t)dt-In 2 •£ (1 + t)aPv(t)dj, where /'„(i) is the Legendre function of degree v. It is well known [2, p. 316, Eq. (15)] that J '>a + lp2/ i ,\ (I + t)aP (t)dt =^ ^a>-l. -i U ; pW r(a + v + 2)r(a + 1 -1») ' Differentiating (3) with respect to a gives £(1 +ffln(l +QPv(t)dt (4) 2a + 1r2(a+l) = r^ + . + ^a+i-,)0"^2^^1)-^^^^-^^1^ with i//(x) = r'(x)/r(x) the logarithmic derivative of the gamma function. The assertion (1) now follows by inserting (3) and (4) in (2) and by using the recurrence relations r(x + 1) = xT(x), ip(x + l)= 0(x) + 1/x, together with the fact that for any integer Received May 31, 1978. AMS (MOS) subject classifications (1970). Primary 33A65. © 1979 American Mathematical Society 0025-571 8/79/0000-0069/S01.50 742 License or copyright restrictions may apply to redistribution; see https://www.ams. org/journal-terms-of-use ON THE PRECEDING PAPER BY JAMES L. BLUE 743 r>0, ^L±A -(-irV! ase-0. r(-r + e) v ' The method of proof also allows the evaluation of integrals of the form "„,*(«) = So X"[ln Wxy\*Pn*(x) dx> by repeatedly differentiating (4) with respect to a. Department of Computer Sciences Purdue University West Lafayette, Indiana 47907 1. J. L. BLUE, "A Legendre polynomial integral," Math. Comp., v. 33, 1979, pp. 739-741. 2. A. ERDÉLYI (Ed.), Tables of Integral Transforms, Vol. II, McGraw-Hill, New York, 1954. License or copyright restrictions may apply to redistribution; see https://www.ams. org/journal-terms-of-use
White organic light-emitting devices using a phosphorescent sensitizer

The efficiency of white organic light-emitting devices has been improved dramatically by the introduction of a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)3] as a sensitizer. Ir(ppy)3 and 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl) are codoped into 4,4′-N,N′-dicarbazole-biphenyl (CBP) host. The chromaticity of white emission can be tuned by adjusting the thickness of the codoped CBP layer or the concentration of Ir(ppy)3. The luminance efficiency of these devices is affected at the same time due to the severe difference in efficiency between the two primary emission peaks.
Boundary height correlations in a two-dimensional Abelian sandpile

Boundary height distributions of the two-dimensional Abelian sandpile model are studied in the self-organized critical state. All height probabilities are calculated explicitly both at open and closed boundaries. The leading asymptotic term of the corresponding correlation functions is observed to behave as r-4 when r to infinity . On the basis of conformal field theory predictions the bulk height correlators are shown to have the same critical exponents as boundary ones. All heights seem to be identified with appropriate counterparts of the local energy operator in the zero-component Potts model.
High‐resolution near‐infrared observations of Herbig–Haro flows – I. H2 imaging and proper motions

We present results of an H2 proper motion study of three Herbig-Haro flows: HH 7-11, 25-26 and 33/40. These are the first proper motion measurements for these objects in the near-infrared, and are complementary to a velocity-resolved, echelle spectroscopy study of the H2 line profile from these objects, presented in a companion paper (Paper II, this issue). The results presented here cover a 4-5 year time-span. The HH 7-11 outflow components have high proper motions, ranging between -200 and 450 km s-1. The directions of their propagation are remarkably uniform, leading directly away from the outflow source. This proper motion pattern is in accordance with recent numerical simulations by Volker et al., and leads us to suggest that the HH 7-11 chain is produced by a (pulsed) heavy jet, of which HH 7 is the working surface, driving into a low-density but clumpy medium. The HH 25-26 system is quite intriguing: the shock components furthest from the source have high proper motions (? 200km s-1), while those closest to the source have negligibly small proper motions (? 70 km s-1). This system is interpreted in terms of working surface bow shocks internal to the jet, and a turbulent mixing layer between the flow and the ambient medium. Indeed, HH 26A and 25C may represent the jet being deflected off nearby dense material. The HH 33/40 flow does not show any significant amount of proper motion, with an upper limit of ? 40-70 km s-1. Situated at the terminus of the giant 'parsec-scale' HH 34 outflow, HH 33 is probably the working surface of the outflow while HH 40 must be material caught up in the general flow of the system. Finally, we show that the limb-brightened leading edges of the bow shocks in HH 7 and 33 are resolved. If the widths of these leading edges represent cooling lengths, then the shocks are probably C-type, as opposed to J-type, bow shocks driving through pre-shock material with <1-mG magnetic fields.
Theory of electrophoretic separations. Part II: Construction of a numerical simulation scheme and its applications

The mathematical model outlined in Part I is recast in a form suitable for numerical computation. The spatial derivatives are replaced by finite-difference expressions, which leads to a set of ordinary differential equations coupled to a set of nonlinear algebraic relations. This system is solved using existing integration techniques. The resulting algorithm simulates the characteristic behavior of the classical modes of electrophoresis, which is shown by examples involving moving boundary electrophoresis and isoelectric focusing. In the first example two different integration schemes are used and their accuracy and stability investigated. The second example illustrates the versatility of the methodology.