Miracle-dz/UniFAR-FTUs huggingface dataset:
Representations and uses of light distribution functions

At their lowest level, all rendering algorithms depend on models of local illumination to define the interplay of light with the surfaces being rendered. These models depend both on the representations of light scattering at a surface due to reflection and to an equal extent on the representation of light sources and light fields. Both emission and reflection have in common that they describe how light leaves a surface as a function of direction. Reflection also depends on an incident light direction. Emission can depend on the position on the light source We call the functions representing emission and reflection light distribution functions (LDF's). There are some difficulties to using measured light distribution functions. The data sets are very large--the size of the data grows with the fourth power of the sampling resolution. For example, a bidirectional reflectance distribution function (BRDF) sampled at five degrees angular resolution, which is arguably insufficient to capture highlights and other high frequency effects in the reflection, can easily require one and a half million samples. Once acquired this data requires some form of interpolation to use them. Any compression method used must be efficient, both in space and in the time required to evaluate the function at a point or over a range of points. This dissertation examines a wavelet representation of light distribution functions that addresses these issues. A data structure is presented that allows efficient reconstruction of LDFs for a given set of parameters, making the wavelet representation feasible for rendering tasks. Texture mapping methods that take advantage of our LDF representations are examined, as well as techniques for filtering LDFs, and methods for using wavelet compressed bidirection reflectance distribution functions (BRDFs) and light sources with Monte Carlo path tracing algorithms. The wavelet representation effectively compresses BRDF and emission data while inducing only a small error in the reconstructed signal. The representation can be used to evaluate efficiently some integrals that appear in shading computation which allows fast, accurate computation of local shading. The representation can be used to represent light fields and is used to reconstruct views of environments interactively from a precomputed set of views. The representation of the BRDF also allows the efficient generation of reflected directions for Monte Carlo array tracing applications. The method can be integrated into many different global illumination algorithms, including ray tracers and wavelet radiosity systems.
On some random forests with determinantal roots

Consider a finite weighted oriented graph. We study a probability measure on the set of spanning rooted oriented forests on the graph. We prove that the set of roots sampled from this measure is a determinantal process, characterized by a possibly non-symmetric kernel with complex eigenvalues. We further derive several results relating this measure to the Markov process associated with the starting graph, to the spectrum of its generator and to hitting times of subsets of the graph. In particular, the mean hitting time of the set of roots turns out to be independent of the starting point, conditioning or not to a given number of roots. Wilson’s algorithm provides a way to sample this measure and, in absence of complex eigenvalues of the generator, we explain how to get samples with a root number approximating a prescribed integer. We also exploit the properties of this measure to give some probabilistic insight into the proof of an algebraic result due to Micchelli and Willoughby [12].
Scientific representation: against similarity and isomorphism

I argue against theories that attempt to reduce scientific representation to similarity or isomorphism. These reductive theories aim to radically naturalize the notion of representation, since they treat scientist's purposes and intentions as non-essential to representation. I distinguish between the means and the constituents of representation, and I argue that similarity and isomorphism are common but not universal means of representation. I then present four other arguments to show that similarity and isomorphism are not the constituents of scientific representation. I finish by looking at the prospects for weakened versions of these theories, and I argue that only those that abandon the aim to radically naturalize scientific representation are likely to be successful.
Clutter suppression for multichannel synthetic aperture radar ground moving target indication system with the capability of high-resolution wide-swath imaging

Abstract. Clutter suppression is a key step for efficient detection of moving targets and accurate estimation of their parameters. Current clutter suppression approaches are available for the case in which clutter signals of each channel are free from Doppler ambiguity. However, for a multichannel high-resolution wide-swath (HRWS) synthetic aperture radar (SAR) system, the received echoes of each channel suffer Doppler ambiguity, thus current clutter suppression approaches may not perform well. To address this issue, the signal models of stationary and moving targets with Doppler ambiguity should be derived. This paper presents their analytical models in the complex image domain by two-dimensional azimuth compression, from which the linear coupling of a moving target induced by radial velocity can be eliminated, and thus signal-to-noise ratio loss caused by this linear coupling can be avoided. Considering that there is a difference between stationary and moving targets in the complex image domain, a clutter suppression approach for a multichannel HRWS SAR system is proposed. The simulated results and real data processing results both validate the proposed approach.
Electrical and Optical Studies in Gallium Antimonide

Hall effect, photoluminescence, and photoconductivity measurements on residual acceptors in GaSb grown by the Bridgman method, are presented and discussed with emphasis on the determination of energy level positions. The effect of thermal annealing or Li-diffusion on the behavior of the energy levels of residual acceptors is investigated to ascertain the nature of doubly-ionizable acceptors. Photoluminescence data on the Au-GaSb Schottky barrier give additional results confirming that the rediual acceptor is doubly ionizable. Direct evidence for the defect configuration is also presented.
High-frequency dynamics in delayed semiconductor lasers with short external cavity

We analyze the dynamics of a laser diode subject to optical feedback from a short external cavity (EC), i.e. with an EC round-trip time much smaller than the period of the laser relaxation oscillations (RO). Our numerical simulations are based on the Lang-Kobayashi (LK) equations for single mode edge-emitting lasers subject to weak/moderate optical feedback. A new, detailed, Hopf bifurcation analysis shows that LK equations admist both supercritical and subcritical Hopf bifurcation points. Subcritical Hopf points lead to time-periodic pulsating intensity solutions with a frequency close to half the RO frequency. In contrast, from supercritical Hopf bifurcatiosn emerge harmonic intensity oscillations with a frequency either close to the RO frequency or to the EC frequency. Microwave oscillations are obtained, as a result of a beating between two EC modes. In general, these high frequency dynamics are stable only for a small range of feedback parameters. However, we find that decreasing the α factor largely improves the stability of the microwave oscillations and makes it possible to observe pulsating intensity solutions for a larger range of EC length. The high frequency intensity solutions of laser diodes with short EC are thought to be of great interest for new applications in all optical signal handling. Our results motivate new theoretical studies of LK equations with short EC.
Transmission electron microscopy investigation of dislocations in forward-biased 4H-SiC p–i–n diodes

When a 4H-SiC p–i–n diode is operated under forward biasing, it rapidly degrades, and the degradation is accompanied by the generation of a high density of stacking faults in the active region of the device. In this letter, the partial dislocations bounding the stacking faults have been investigated by transmission electron microscopy. They are found to be in the form of single leading partial half-loops with a 13〈1010〉 Burgers vector that bound triangular-shaped stacking faults. Two sides of each faulted loop are bound by two partial dislocation segments lying along different 〈1210〉 directions, while the other edge of the triangular stacking fault is a surface (or interfacial) step. The core nature of the two segments has been determined by the technique of large-angle, convergent-beam electron diffraction, and found to be different: one has a silicon core, while the other has a carbon core.
Strength and deformation characteristics of steel fibrous concrete beams

The results of an analytical investigation of the flexural behaviour of Steel Fibre Reinforced Concrete (SFRC) beams are presented. The complete response of the SFRC beams under displacement controlled static loading was obtained using nonlinear Finite Element (FE) techniques implemented with the help of ATENA 2D software. Issues relating to the behaviour of SFRC which have a direct bearing on the FE modelling are discussed with relevance to the software employed for the nonlinear analysis. Constitutive models amenable to numerical analysis for steel fibrous concrete are presented. The structural response throughout the loading regime was captured in terms of the load-deflection behaviour, which in addition to the post-peak response characterized the failure mode of the test beams. The crack patterns at crack initiation and at the end of the tests were also recorded. Experimental results from the specimens of two other investigators were used as control values for this investigation. The response of the specimens of this investigation was evaluated in terms of initial tangent stiffness, peak loads and toughness. Good match was obtained between the results from this investigation and corresponding experimentally obtained values, wherever available. The influence of the fibre content is reflected in the observed trends in peak loads, deflection at peak loads and toughness, which are in broad agreement with known behavioral patterns of SFRC.
A Bayesian Learning Coefficient of Generalization Error and Vandermonde Matrix-Type Singularities

The coefficient of the main term of the generalization error in Bayesian estimation is called a Bayesian learning coefficient. In this article, we first introduce Vandermonde matrix type singularities and show certain orthogonality conditions of them. Recently, it has been recognized that Vandermonde matrix type singularities are related to Bayesian learning coefficients for several hierarchical learning models. By applying the orthogonality conditions of them, we show that their log canonical threshold also corresponds to the Bayesian learning coefficient for normal mixture models, and we obtain the explicit computational results in dimension one.
Method and device for identifying different species of honeybees

A method and device have been provided for distinguishing Africanized honeybees from European honeybees. The method is based on the discovery of a distinct difference in the acoustical signatures of these two species of honeybees in flight. The European honeybee signature has a fundamental power peak in the 210 to 240 Hz range while the Africanized honeybee signature has a fundamental power peak in the 260 to 290 Hz range. The acoustic signal produced by honeybees is analyzed by means of a detecting device to quickly determine the honeybee species through the detection of the presence of frequencies in one of these distinct ranges. The device includes a microphone for acoustical signal detection which feeds the detected signal into a frequency analyzer which is designed to detect the presence of either of the known fundamental wingbeat frequencies unique to the acoustical signatures of these species as an indication of the identity of the species and indicate the species identity on a readout device.
Calibration of one-dimensional boosted kinetic codes for modeling high-intensity laser-solid interactions

An efficient means of performing kinetic simulations of oblique-incidence laser–plasma interaction via a relativistic Lorentz transformation is described in detail. Comparisons are made between one-dimensional boost codes and previous two-dimensional particle-in-cell (PIC) simulations in an effort to define benchmarks for modeling high-intensity, short-pulse interactions. Apparent discrepancies between results obtained using PIC and Vlasov codes are resolved, and some pitfalls involved with both techniques are identified.
Ensemble Sensitivity Tools for Assessing Extratropical Cyclone Intensity and Track Predictability

AbstractThis paper applies ensemble sensitivity analysis to a U.S. East Coast snowstorm on 26–28 December 2010 in a way that may be beneficial for an operational forecaster to better understand the forecast uncertainties. Sensitivity using the principal components of the leading empirical orthogonal functions (EOFs) on the 50-member European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble identifies the sensitive regions and weather systems at earlier times associated with the cyclone intensity and track uncertainty separately. The 5.5-day forecast cyclone intensity uncertainty in the ECMWF ensemble is associated with trough and ridge systems over the northeastern Pacific and central United States, respectively, while the track uncertainty is associated with a short-wave trough over the southern Great Plains. Sensitivity based on the ensemble mean sea level pressure difference between two run cycles also suggests that the track's shift between the two cycles is linked with the initial errors in.
Adaptive fuzzy logic control based on integral criterion

The paper describes a method of a fuzzy logic controller adaptation that is founded on a reference model and integral criterion. An adaptation law is based on finding an adaptive gain coefficient and lead-lag filter time constant by using quantitative relations that, link reference model parameters and integral criterion. Once calculated the output of the hybrid fuzzy controller is filtered by an adaptive lead-lag filter. The proposed adaptive fuzzy controller has been tested in the angular speed control loop of a permanent magnet synchronous motor (PMSM) drive. The simulation results confirmed its effectiveness.
Entrainment and Detrainment in Cumulus Clouds

Abstract Vertical redistribution of air and its properties inside convective clouds can be studied by standard thermodynamic analyses (Paluch and saturation point diagrams) if the clouds are nonprecipitating and ice free. It is shown from such analysis that the linear patterns often seen in these diagrams can result from continued “lateral” entrainment. The observations are consistent with the hypothesis that buoyancy sorting is an important factor in determining cloud composition. This yields a simple, graphical means for estimating the thermodynamic properties of in-cloud air at any pressure. Field observations of detrained fluxes near cumulus clouds reveal the existence of rather thin detrainment layers which can occur anywhere over the cloud layer. These observations are shown to be consistent with the conclusion of Bretherton and Smolarkiewicz that detrainment is governed by vertical gradients of cloud buoyancy. This allows prediction of detrainment regions from cloud base temperature and pressure an.
Comparación de las Cartas de Control Univariadas con Transformación en la Medida de Variabilidad

Monitoring of the variability of a quality feature using univariate control charts in a production processiscritical to detect signifi cant changes in order to allow the engineer to control the condition and behavior of thatfeature. Alwan [1] proposes the study to improve the sensitivity in univariate control charts by transforming the measure of variability transformation taking the standard deviation for the logarithmic EWMA chartsproposed by Crowder [2], fi nding an improvement in sensitivity to small changes in variability. This sensitivity improves in HV CUSUM proposal which applies a transformation to the standard deviation of three parameters [3] fi rst proposed by Castagliola [3].
10-W peak power from a gain-switched picosecond all-semiconductor laser

Gain-switching of laser diodes might be the most convenient way to generate picosecond laser pulses. The outstanding features of gain-switched laser diodes are a rich choice of wavelength and an easy synchronization to an external trigger source. To broaden the field of applications we pushed the peak power to the 10 W level while maintaining the essential characteristics of the laser source. In a master oscillator power amplifier (MOPA) configuration a tapered amplifier is used to increase the output from 10 mW to 160 mW average power. Second harmonic generation is demonstrated in a single pass setup, which results in 6.5 mW average power at 532 nm with a repetition rate of 80 MHz.
STOCHASTIC LIOUVILLE EQUATIONS

When a dynamical system has a perturbation which is considered as a stochastic process, the Liouville equation for the system in the phase space or the space of quantum‐mechanical density operators is a sort of stochastic equation. The ensemble average of its formal integral defines the relaxation operator Φ(t) of the system. By the definition Φ(t) = exp K(t), the cumulant function K(t) may be introduced. Some general properties are first discussed for a simple example of an oscillator with random frequency modulation and then, concepts of slow and fast modulation are considered. These concepts can be generalized to more general types of stochastic Liouville equations. It is shown that by various possibilities of defining generalized exponential functions, this approach may be useful to understand some essential features of the problem from an unified point of view.
The Luminosity Function of the EGRET Gamma-Ray Blazars

We examine the properties of the gamma-ray active galactic nuclei (AGNs) detected by EGRET. We calculate the evolution and luminosity function of the gamma-ray-loud AGNs, and we estimate the contribution this source class makes to the diffuse extragalactic gamma-ray background. These calculations are based on a sample of EGRET observations complete through the Compton Gamma-Ray Observatory observing Cycle 4. We use the Ve/Va test to measure the luminosity evolution and the nonparametric c--method to estimate the de-evolved luminosity function. We also consider inclusion in the 1 Jy radio catalog of Kühr et al. (1981) as an additional criterion to help guard against selection effects resulting from incomplete redshift determinations for AGNs in our sample. Our results include evidence for a low-luminosity cutoff in the gamma-ray AGN luminosity distribution, a more precise estimate of the contribution of these objects to the diffuse extragalactic gamma-ray background, and constraints on the gamma-ray production mechanism based upon the statistics implied by relativistic beaming of the emission. We discuss the implications of these findings for models of AGN unification and the relationship of gamma-ray to radio emission.
Publications of the Astronomical Society of the Pacific 106: 616-618, 1994 June Ginga and ROSAT Observations of the Cataclysmic Variable S193

The cataclysmic variable SI93 was observed with the Ginga and ROSAT satellites, along with ground-based optical observations. The bremsstrahlung temperatures and the column densities derived from these two observations are noticeably different. However, since the observations were separated by 3 yr and took place at different optical magnitudes, it is not clear whether this is related to an intrinsic change in the system or to a two component source of X rays. While the X-ray data are not sufficient to accomplish a detailed analysis for periodicities, the Ginga data place an upper limit of 40% on the amplitude of any sinusoidal modulation.
Role of Brownian motion in the enhanced thermal conductivity of nanofluids

We have found that the Brownian motion of nanoparticles at the molecular and nanoscale level is a key mechanism governing the thermal behavior of nanoparticle–fluid suspensions (“nanofluids”). We have devised a theoretical model that accounts for the fundamental role of dynamic nanoparticles in nanofluids. The model not only captures the concentration and temperature-dependent conductivity, but also predicts strongly size-dependent conductivity. Furthermore, we have discovered a fundamental difference between solid/solid composites and solid/liquid suspensions in size-dependent conductivity. This understanding could lead to design of nanoengineered next-generation coolants with industrial and biomedical applications in high-heat-flux cooling.
Fitting improved accretion disk models to the multiwavelength continua of quasars and active galactic nuclei

Fits to the ultraviolet-optical-infrared spectra of 60 quasars and active galactic nuclei (AGNs) are investigated, using black hole accretion disk models. The disk is assumed to be geometrically thin and optically thick. The observed spectrum from a black hole accretion disk, rotating (Kerr) or nonrotating (Schwarzschild), is transformed by the geometric inclination effect, Doppler shifts, gravitational redshifts, and gravitational focusing. These effects alter the locally emitted fluxes and produce harder spectra for an observer at higher inclination angles. The relativistic corrections are much more significant in the Kerr geometry since the inner edge of the disk is much closer to the rotating black hole. A simple inverse relation between the inferred black hole mass and the assumed inclination angle was found in the Kerr case, while the inferred accretion rate (solar masses/yr) remains independent of the angle. In the Schwarzschild case, the ratio of the inferred accretion rate to the black hole mass remains roughly constant when the viewing angle changes. In both geometries, low-redshift Seyfert galaxies have relatively low accretion rates, only a few percent of their Eddington luminosities, while the most luminous quasars are accreting near their Eddington limits. 65 refs.
Structure of a Large-Radius Pinch Discharge

A large-radius pinch discharge produces a series of cylindrically symmetric, inwardly propagating current sheets and associated magnetic fields in a form convenient for detailed study of the j x B interactions basic to all schemes of electromagnetic gas acceleration. The discharge is examined by streak and Kerr cell photography, magnetic probes, spectroscopy, microwaves, and terminal measurements of current and voltage fluctuations, in order to determine the detailed distribution of the currents and fields as functions of radius and time. The initiation of the main discharge in a uniform peripheral ring is found to be primarily an inductive effect, conditioned somewhat by the presence of the adjacent insulator surface. Spectrograms of discharges in argon, nitrogen, and helium show singly and doubly ionized species indicating that particles of energy in excess of 25 ev are participating in the breakdown. A precursor front is observed to propagate ahead of the first current sheet and is identified tentatively as a gasdynamic shock. Another precursor, propagating many times faster, preionizes the gas slightly, prior to the arrival of the first current sheet. (auth)