Miracle-dz/UniFAR-FTUs huggingface dataset:
Oscilações paramétricas: uma simulação numérica

A pendulum with oscillating attached point and a pendulum with the periodically changing length belongs to a class of physical systems called parametric. In the regime of small oscillations such systems are very well described through the Mathieu equations. In this work the equations of motion for these two parametric oscillators are numerically integrated without any restriction of small oscillations. Poincare maps are obtained, showing that the chaotic and stable behavior can coexist for a given set of parameters which characterizes the system.
CONFIDENCE BANDS IN QUANTILE REGRESSION

Let (X1, Y1), …, (Xn, Yn) be independent and identically distributed random variables and let l(x) be the unknown p-quantile regression curve of Y conditional on X. A quantile smoother ln(x) is a localized, nonlinear estimator of l(x). The strong uniform consistency rate is established under general conditions. In many applications it is necessary to know the stochastic fluctuation of the process {ln(x) – l(x)}. Using strong approximations of the empirical process and extreme value theory, we consider the asymptotic maximal deviation sup0≤x≤1 |ln(x) − l(x)|. The derived result helps in the construction of a uniform confidence band for the quantile curve l(x). This confidence band can be applied as a econometric model check. An economic application considers the relation between age and earnings in the labor market by means of parametric model specification tests, which presents a new framework to describe trends in the entire wage distribution in a parsimonious way.
Astronomical optical frequency comb generation in nonlinear fibres and ring resonators: optimization studies

We here discuss recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam. Two different platforms (and approaches) are numerically and experimentally investigated targeting medium and low resolution spectrographs at astronomical facilities in which innoFSPEC is currently involved. In the first approach, a frequency comb is generated by propagating two lasers through three nonlinear stages – the first two stages serve for the generation of low-noise ultra-short pulses, while the final stage is a low-dispersion highly-nonlinear fibre where the pulses undergo strong spectral broadening. In our approach, the wavelength of one of the lasers can be tuned allowing the comb line spacing being continuously varied during the calibration procedure – this tuning capability is expected to improve the calibration accuracy since the CCD detector response can be fully scanned. The input power, the dispersion, the nonlinear coefficient, and fibre lengths in the nonlinear stages are defined and optimized by solving the Generalized Nonlinear Schrodinger Equation. Experimentally, we generate the 250GHz line-spacing frequency comb using two narrow linewidth lasers that are adiabatically compressed in a standard fibre first and then in a double-clad Er/Yb doped fibre. The spectral broadening finally takes place in a highly nonlinear fibre resulting in an astro-comb with 250 calibration lines (covering a bandwidth of 500 nm) with good spectral equalization. In the second approach, we aim to generate optical frequency combs in dispersion-optimized silicon nitride ring resonators. A technique for lowering and flattening the chromatic dispersion in silicon nitride waveguides with silica cladding is proposed and demonstrated. By minimizing the waveguide dispersion in the resonator two goals are targeted: enhancing the phase matching for non-linear interactions and producing equally spaced resonances. For this purpose, instead of one cladding layer our design incorporates two layers with appropriate thicknesses. We demonstrate a nearly zero dispersion (with +/- 4 ps/nm-km variation) over the spectral region from 1.4 to 2.3 microns. The techniques reported here should open new avenues for the generation of compact astronomical frequency comb sources on a chip or in nonlinear fibres.
IUE observations of the peculiar M giant HD 4174

Ultraviolet spectra of the peculiar M giant HD 4174, which may possess a significant magnetic field, are shown to exhibit numerous high-excitation emission lines and no background continuum. Ionization equilibrium temperatures for species observed range from 6000 K (Mg II) up to 200,000 K (N v). Density diagnostics using line ratios indicate electron density of 3 x 10 to the 9th power per cu cm in the emission-line-forming region, which favorably compares with coronal model parameters previously suggested for this star. High-resolution Ca II and Mg II profiles suggest an enhanced chromospheric temperature rise. Comparison with symbiotic objects and a high-excitation planetary nebula reveals similarities among these objects.
Properties of a Simulated Convective Boundary Layer in an Idealized Supercell Thunderstorm Environment

AbstractNearly all previous numerical simulations of supercell thunderstorms have neglected surface fluxes of heat, moisture, and momentum. This choice precludes horizontal inhomogeneities associated with dry boundary layer convection in the near-storm environment. As part of a broader study on how mature supercell thunderstorms are affected by a convective boundary layer (CBL) with quasi-two-dimensional features (i.e., boundary layer rolls), this paper documents the methods used to develop a realistic CBL in an idealized environment supportive of supercells. The evolution and characteristics of the modeled CBL, including the horizontal variability of thermodynamic and kinematic quantities known to affect supercell evolution, are presented. The simulated rolls result in periodic bands of perturbations in temperature, moisture, convective available potential energy (CAPE), vertical wind shear, and storm-relative helicity (SRH). Vertical vorticity is shown to arise within the boundary layer through the tilt.
A Theory of Continuum Economies with Independent Shocks and Matchings

Numerous economic models employ a continuum of negligible agents with a sequence of idiosyncratic shocks and random matchings. Several attempts have been made to build a rigorous mathematical justification for such models, but these attempts have left many questions unanswered. In this paper, we develop a discrete time framework in which the major, desirable properties of idiosyncratic shocks and random matchings hold. The agents live on a probability space, and the probability distribution for each agent is naturally replaced by the population distribution. The novelty of this approach is in the assumption of unknown identity. Each agent believes that initially he was randomly and uniformly placed on the agent space, i.e., the agent's identity (the exact location on the agent space) is unknown to the agent.
On Cloud-Top Determination from Gemini-5.

Abstract A hand-held spectrograph-camera has been used by the Gemini-5 astronauts to obtain spectra of sunlight reflected from clouds in the region of the oxygen “A” band near 7600 A. The transmittance measurements at selected wavelengths inside the band offered a means of measuring the amount of oxygen in the optical path, and, therefore, the cloud top altitude. Results of the observations are presented, with verification of four cases indicating the validity of the experiment. A method for computing a correction factor, needed to account for the extra absorption inside the cloud, is developed. This method gives the dependences of the correction factor on the solar zenith, viewing and azimuthal angles. Results of computations by this method are compared with earlier results based on the two-streams theory of Schuster.
Simulating Topological Effects with Photons in Coupled QED Cavity Arrays

We provide a pedagogical account of an early proposal realizing fractional quantum Hall effect (FQHE) using coupled quantum electrodynamics (QED) cavity arrays (CQCAs). We start with a brief introduction on the basics of quantum Hall effects and then review the early proposals in the simulation of spin-models and fractional quantum Hall (FQH) physics with photons in coupled atom-cavity arrays. We calculate the energy gap and the overlap between the ground state of the system and the corresponding Laughlin wavefunction to analyze the FQH physics arising in the system and discuss possibilities to reach the ground state using adiabatic methods used in Cavity QED.
Admissible consensus analysis for high‐order linear singular swarm systems with multiple time‐varying delays and topology variances

Admissible consensus analysis problems for high‐order linear time‐invariant singular swarm systems with multiple time delays and time‐varying interaction topologies are investigated. First, necessary and sufficient conditions for admissible consensus are presented, and admissible consensus problems are transformed into admissible problems of multiple lower dimensional singular systems. Then, on the basis of the first equivalent form, explicit expressions of consensus functions are given, where the impacts of initial states of agents and protocols, time delays and topology variances are determined, respectively. Moreover, it is shown that if interaction topologies are balanced, then swarm systems with the same initial states but different interaction topologies and different time delays have an identical consensus function. Finally, numerical simulations are given to demonstrate theoretical results. Copyright © 2013 John Wiley & Sons, Ltd.
Iron-Line Diagnostics of the Jets of SS 433

The X-ray spectra of SS 433 were measured with ASCA at a precession phase 0.48 when the Dopplershifted iron lines from both the receding and approaching jets were clearly separated. The X-ray emission lines of SS 433 were analyzed on the basis of a numerical model of the radiatively cooling jets. The measured intensities of the iron-emission lines were compared with the results from numerical calculations in order to constrain the physical parameters of the jets, such as the temperature, mass outflow rate, density, and length. We also studied the emission lines from elements with smaller atomic number, and found that these lines were heavily absorbed only in the receding jet. This implies the existence of absorbing gas in a precessing plane perpendicular to the jets.
Stable zeros of sampled low-pass systems

Abstract This paper studies analytical forms of criteria for ensuring that all zeros of a discrete system are stable when a continuous-time, strictly proper and low-pass plant is sampled by use of a zero order hold. Necessary and sufficient conditions for stable zeros of a sampled system are developed. They are related to coefficients of a continuous-time transfer function and to a sampling period. This paper also presents sufficient conditions which are expressed in terms of coefficients of a continuous-time transfer function.
A structure theorem for the commutant of a class of cyclic subnormal operators

An m-measure is defined to be a measure IL such that the analytic bounded point evaluations of p2(ft) iS the open unit disk D in the complex plane, and the weak* closure of the analytic polynomials in Lf(tL) is the set of bounded analytic functions on D. A complete characterization of p2(tL) n LX(yt), the commutant of the cyclic subnormal operator of multiplication by 7 on p2 ( t), is then obtained. In this paper a complete characterization is given of the commutant of a class of cyclic subnormal operators closely related to the unilateral shift. An operator S on a Hilbert space X is subnormal if there is a Hilbert space Xr containing X#' and a normal operator N on X such that N(,#') c X#' and S = NjY (the restriction of N to k'). The weak* topology on B(-') is the topology which B(.Xk) has as the Banach space dual of the trace class operators [4]. A measure ts is always a compactly supported, positive regular Borel measure on the complex plane, C. If S is a cyclic subnormal operator, then there exists a measure yt such that S is unitarily equivalent to S , the operator of multiplication by z on p2(ft) = the closure of the analytic polynomials in L2(yt) [4]. Yoshino's Theorem [4] states that the map from p2(.t) n Ll([) onto { SI,}' = the commutant of Sl,, given by f (S,,) = multiplication by 4, is an isometric isomorphism and a weak* homeomorphism. For functions f, g in L2(tt), (f, g) -ff gdet, If1112 = ((f f)1/)2 and Ilf II,, denotes the ti-essential supremum of f. Let m denote normalized arc length measure on aD, the boundary of the open unit disk. Thus Sr, is the unilateral shift. A class of measures with many of the properties of m will be defined after some notation is set. If ,t is a measure, then B(,u), the set of bounded point evaluations of p2(t), consists of those X in C for which the linear functional p p(X) has a bounded extension from the polynomials to p2(n4). Equivalently, X E B([t) if and only if there exists k. in p2(t,) such that p(X) = (p, kx) for all polynomials p. Bj(p4) the set of analytic bounded point evaluations of P2(11), is the largest open subset of B(i) such that the function
Concerning the Form of the Loudness Function

In order to examine certain possible irregularities in the loudness function, the method of adjustment was used to halve and double the loudness of a 1000‐cy tone at the levels 30, 60, 90, and 120 db re 0.0002 μbar. The results tend partially to confirm some of the irregularities found by Robinson. The results also indicate that a reasonable approximation to the loudness function is the rule that a change of 10 db corresponds to a loudness ratio of 2:1. This means that loudness grows approximately as a power function of intensity. It is noted that the power function also describes the relation between psychological magnitude and stimulus magnitude on a dozen other perceptual continua.
Purfication of quantum trajectories

A key concept in the modern theory of open quantum systems is the notion of indirect measurement as introduced by Kraus [5]. An indirect measurement on a quantum system is a (direct) measurement of some quantity in its environment, made after some interaction with the system has taken place. When we make such a measurement, our description of the quantum system changes in two ways: we account for the flow of time by a unitary transformation (following Schrodinger), and we update our knowledge of the system by conditioning on the measurement outcome (following von Neumann). If we then repeat the indirect measurement indefinitely, we obtain a chain of random outcomes. In the course of time we may keep record of the updated density matrix Qt, which at time t reflects our best estimate of all observable quantities of the quantum system, given the observations made up to that time. This information can in its turn be used to predict later measurement outcomes. The stochastic process St of updated states, is the quantum trajectory associated to the repeated measurement process. By taking the limit of continuous time, we arrive at the modern models of continuous observation: quantum trajectories in continuous time satisfying stochastic Schrodinger equations [3], [4], [2], [1]. These models are employed with great success for calculations and computer simulations of laboratory experiments such as photon counting and homodyne field detection. In this paper we consider the question, what happens to the quantum trajectory at large times. We do so only for the case of discrete time, not a serious restriction indeed, since asymptotic behaviour remains basically unaltered in the continuous time limit.
Lidar as a tool for fisheries management

This paper describes the results of a series of airborne observations of sardine schools off the coast of California in the fall of 2010. The lidar system used a linearly-polarized transmitter and a single receiver that was sensitive to the backscattered light in the orthogonal polarization. The aircraft was also equipped with a camera to photograph schools. The camera had a broader swath than the lidar, so was able to see more of the schools at the surface. However, the lidar detected schools much deeper in the water, was not hampered by waves and sun glare, and could survey at night. The combination of lidar and photographs proved to be a very powerful survey tool for sardines, since the latter was able to identify surface targets that appear very similar to fish schools in the lidar return. Examples of these include floating mats of kelp and ship wakes.
BAYESIAN PREDICTION FOR SPATIAL GENERALISED LINEAR MIXED MODELS WITH CLOSED SKEW NORMAL LATENT VARIABLES

Spatial generalised linear mixed models are used commonly for modelling non‐Gaussian discrete spatial responses. In these models, the spatial correlation structure of data is modelled by spatial latent variables. Most users are satisfied with using a normal distribution for these variables, but in many applications it is unclear whether or not the normal assumption holds. This assumption is relaxed in the present work, using a closed skew normal distribution for the spatial latent variables, which is more flexible and includes normal and skew normal distributions. The parameter estimates and spatial predictions are calculated using the Markov Chain Monte Carlo method. Finally, the performance of the proposed model is analysed via two simulation studies, followed by a case study in which practical aspects are dealt with. The proposed model appears to give a smaller cross‐validation mean square error of the spatial prediction than the normal prior in modelling the temperature data set.
The Estimation of Some Continuous Time Models

When a continuous time model is estimated from its non-recursive discrete approximation, the presence of identities and exogenous variables in the system does not preclude the use of standard procedures. However, if we wish to use the exact discrete model for estimation purposes, the treatment of identities and exogenous variables is not so straightforward. It is found that the procedure based on the exact discrete model is unlikely to be affected by the presence of identities, but when exogenous variables occur in the system some sort of approximation is usually necessary before the model can be estimated with discrete data. An approximate model is constructed to deal with the latter case and the asymptotic properties of estimators derived from this model are investigated. UNDER CERTAIN CONDITIONS, a stochastic model represented by a system of continuously distributed lags can be regarded as the solution of a system,of linear stochastic differential equations. Two general approaches are available if we wish to estimate the parameters of such a system by conventional methods and with discrete data.2 The first approach (see [1 and 2]) is to take a discrete approximation to the model and estimate the approximate model by standard methods. The second approach makes use of the discrete model which is known to correspond to the continuous time model in the sense that observations at equidistant points in time that are generated by the latter system also satisfy the former. The main advantage of the second approach is that no specification error is involved, so that it is possible in some cases to obtain consistent and asymptotically efficient estimators of the parameters in the model. In addition to the arguments of asymptotic theory, the results of a previous study [8] have given some recommendation to the second approach on the basis of small sampling performance. However, the model used in the sampling experiment of this study was relatively simple and it is the aim of the present paper to discuss the use of the second approach in more complicated models. The complications with which we will be concerned are the presence of identities and exogenous variables; both these complications may be expected to occur in more realistic economic, models. Before the procedure is viable when there are identities in the model, we must ascertain whether the disturbance in the exact discrete model has a non-singular
Neutrinos and the Higgs Boson in Split Supersymmetry

The effects of a Higgs boson mass of 126 GeV are studied in a Split Supersymmetric model with Bilinear R-Parity violation. This model allows for the explanation for the neutrino masses and mixing angles, and has the gravitino as Dark Matter candidate. We fin d constraints on the parameters that define the model, and find complete consistency with the exper imental results at the LHC.
Multigrid Method for Maxwell's Equations

In this paper we are concerned with the efficient solution of discrete variational problems related to the bilinear form ({\bf curl}\! $\cdot$, {\bf curl}\! $\cdot)_{{\fontsize{6}{0pt}\selectfont\textbf{\textit{L}}}^2(\Omega)}$ + ($\cdot,\cdot)_{{\fontsize{6}{0pt}\selectfont\textbf{\textit{L}}}^2(\Omega)}$ defined on \textbf{\textit{H}}$_0$({\bf curl}; $\Omega$). This is a core task in the time-domain simulation of electromagnetic fields, if implicit timestepping is employed. We rely on Nedelec's \textbf{\textit{H}}({\bf curl}; $\Omega$)-conforming finite elements (edge elements) to discretize the problem. We construct a multigrid method for the fast iterative solution of the resulting linear system of equations. Since proper ellipticity of the bilinear form is confined to the complement of the kernel of the {\bf curl} operator, Helmholtz decompositions are the key to the design of the algorithm: ${\cal N}$({\bf curl}) and its complement ${\cal N}$({\bf curl})$^{\bot}$ require separate treatment. Both can be tackled by nodal multilevel decompositions, where for the former the splitting is set in the space of discrete scalar potentials. Under certain assumptions on the computational domain and the material functions, a rigorous proof of the asymptotic optimality of the multigrid method can be given, which shows that convergence does not deteriorate on very fine grids. The results of numerical experiments confirm the practical efficiency of the method.
Excitation of a higher order transverse mode in an optically pumped In0.15Ga0.85N/In0.05Ga0.95N multiquantum well laser structure

We report a comparison between measured and calculated far field data for an optically pumped In0.15Ga0. 85N/In0.05Ga0. 95N multiquantum well laser structure with AlGaN cladding layers. Optical pumping of the semiconductor device was performed with a pulsed 337 nm N2 laser, whose beam was focused to a narrow stripe. A thin upper cladding layer allowed efficient pumping of the In0.15Ga0. 85N/In0.05Ga0. 95N laser structure. Despite high distributed cavity losses of at least 30 cm−1, and although gain occurred in the small active region only, the seventh order transverse mode was supported in a waveguide formed by the entire 5-μm-thick epitaxial layer structure. Excellent agreement is demonstrated between measured and calculated far field patterns of the lasing mode.
Phase-coded approach for controllable generation of acoustical vortices

Based on the acoustic radiation of point source, a phase-coded approach is proposed as a general technology to generate controllable acoustical vortices. For N sources, acoustical vortices can be generated with the phase difference of 2πm/N for the source topological charge m. It is proved that more circular pressure distributions of acoustical vortices with higher pressure peak amplitude can be generated for more sources. The number and spiral direction of phase twists are demonstrated to be determined by m and the maximum topological charge of acoustical vortices is |L|=Fix[(N−1)/2], where Fix(x) rounds the element x toward zero. To produce acoustical vortices with a maximum topological charge L, the minimum source number of Nmin=max(2|L|+1,4) should be employed with the phase difference of 2πL/Nmin and the phase difference resolution is also demonstrated to be π. The phase-coded approach has been verified by a 6-source experiment. The measured distributions of pressure and phase as well as the topologi.