Miracle-dz/UniFAR-FTUs huggingface dataset:
The attenuation of X-rays emitted by supernovae

The attenuation of X-rays in Arnett's C-12 detonation supernova model is computed. The attenuation of X-rays in the filaments of the Crab Nebula is computed using a model for the filaments by Woltjer and a model by Davidson and Tucker. An empirical expression by Gorenstein, Kellogg, and Gursky for the optical thickness of the interstellar medium for three supernova remnants is analyzed.
Studies of the Longitudinal Development of Electron—Photon Cascade Showers

Numerical results of the track lengths of photons and charged particles and the energy deposition as a function of depth out to 10 radiation lengths in copper are presented for the case of electron‐initiated electron—photon cascade showers. The incident energy varied from 50 to 45 000 MeV in these cases.Monte Carlo methods were used to calculate the longitudinal development of the showers in order to obtain the data that are presented. The Bethe—Heitler cross sections which include screening and the correct energy dependence were used from bremsstrahlung and pair production events. The Klein—Nishina formula was used for Compton scattering. Energy losses by ionization collisions were treated as a continuous energy degradation process.
Alfvén Wave Model of Spicules and Coronal Heating

Magnetohydrodynamic simulations are performed for torsional Alfvén waves propagating along an open magnetic flux tube in the solar atmosphere. It is shown that, if the root mean square of the perturbation is greater than ~1 km s-1 in the photosphere, (1) the transition region is lifted up to more than ~5000 km (i.e., the spicule is produced), (2) the energy flux enough for heating the quiet corona (~3.0×105 ergs s-1 cm−2) is transported into the corona, and (3) nonthermal broadening of emission lines in the corona is expected to be ~20 km s-1. We assumed that the Alfvén waves are generated by random motions in the photosphere. As the Alfvén waves propagate upward in the solar atmosphere, longitudinal motions are excited by the nonlinear couplings. The longitudinal motions propagate upward as slow or fast waves and lift up the transition region (i.e., the spicule is produced). A part of the Alfvén waves are reflected in the transition region, but the remaining waves propagate upward to the corona and contribute both to the heating of the corona and the nonthermal broadening of emission lines. The result of our simulation would suggest that the quiet hot corona, nonthermal broadening of lines, and spicules are caused by Alfvén waves that are generated in the photosphere.
Monitoring the heat output of a wood-burning stove

To find a simple means for monitoring the heat output of a wood stove, general engineering models of heat transfer are used to develop a model that predicts the heat output of a stove from measurements of surface temperature. Using the surface area and the measured surface temperature as inputs, the model predicts the heat output of the stove by radiation and natural convection. As a means of verification, surface temperature data from four wood stoves monitored in a calorimeter room are used to make heat output predictions. The predicted heat outputs are then compared with the actual heat outputs measured by the calorimeter room. The predictions involve several potential monitoring schemes:(J) separate temperature measurements for each surface of the stove,() an average temperature measurement for all stove surfaces, and () a single surface temperature measurement. The accuracies of the predictions are characterized by their geometric bias and scatter as well as their predictions of total energy delivere.
A direct numerical simulation study of turbulence and flame structure in transverse jets analysed in jet-trajectory based coordinates

Abstract An ${\mathrm{H} }_{2} / {\mathrm{N} }_{2} $ jet in cross-flow (JICF) of air is studied using three-dimensional direct numerical simulation with and without chemical reaction in order to investigate the role of the complex JICF turbulent flow field in the mechanism of fast fuel-oxidant mixing and of aerodynamic flame stabilization in the near field of the jet nozzle. Focus is on delineating the flow/mixing/chemistry conditions that are necessary and/or sufficient to achieve flame anchoring that ultimately enables the formulation of more reliable and precise guidelines for design of fuel injection nozzles. A mixture averaged diffusion formulation that includes the effect of thermal diffusion is used along with a detailed chemical kinetics mechanism for hydrogen–air combustion. A new parametrization technique is used to describe the jet trajectory: solution of Laplace’s equation upon, and then within, an opportune scalar surface anchored by Dirichlet boundary conditions at the jet nozzle and plume exit from the domain provides a smoothly varying field along the jet path. The surface is selected to describe the scalar mixing and reaction associated with a transverse jet. The derived field, $j(\mathbi{x})$ , is used as a condition to mark the position along the natural jet trajectory when analysing the variation of relevant flow, mixing and reaction quantities in the present direct numerical simulation (DNS) datasets. Results indicate the presence of a correlation between the flame base location in parameter space and a region of low velocity magnitude, high enstrophy, high mixing rate and high equivalence ratio (flame root region). Instantaneously, a variety of vortical structures, well known from the literature as important contributors to fuel-oxidant mixing, are observed in both inert and reactive cases with a considerable span in length scales. Moreover, instantaneous plots from reactive cases illustrate that the most upstream flame tongues propagate close to the trailing edge of the fuel jet potential core near the jet shear layer vortex shedding position. Some degree of asymmetry with respect to the domain mid-plane in the spanwise direction is observed in the averaged fields, both for the inert and reactive cases.
Compact Groups: Local Groups?

It is concluded that faint members found in the vicinities of compact groups (CGs) are gravitationally bound with corresponding groups. All members of CGs, faint and bright, move preferentially in the direction of the elongation of the group. We suppose that the number of faint members may be much larger than previously assumed. These two circumstances should apparently change the conclusion about the short lifetime of CGs. Consequently, many puzzles related to CGs, such as their very existence, the absence of strong radio and infrared sources, and the absence of strong signs of interaction and merging will probably vanish.
Investigating mode competition and three-dimensional features from two-dimensional velocity fields in an open cavity flow by modal decompositions

Shear-layer driven open cavity flows are known to exhibit strong self-sustained oscillations of the shear-layer. Over some range of the control parameters, a competition between two modes of oscillations of the shear layer can occur. We apply both Proper Orthogonal Decomposition and Dynamic Mode Decomposition to experimental two-dimensional two-components time and spaced velocity fields of an incompressible open cavity flow, in a regime of mode competition. We show that, although proper orthogonal decomposition successes in identifying salient features of the flow, it fails at identifying the spatial coherent structures associated with dominant frequencies of the shear-layer oscillations. On the contrary, we show that, as dynamic mode decomposition is devoted to identify spatial coherent structures associated with clearly defined frequency channels, it is well suited for investigating coherent structures in intermittent regimes. We consider the velocity divergence field, in order to identify spanwise coherent features of the flow. Finally, we show that both coherent structures in the inner-flow and in the shear-layer exhibit strong spanwise velocity gradients, and are therefore three-dimensional.
ON THE FU ORIONIS VARIABLE V1515 CYGNI

Optical/infrared photometric and spectrometric observations of the pre-main-sequence FU Ori object V1515 Cyg are presented. Data obtained indicate that this variable star has many features in common with other FU Orionis objects, including a variation of spectral type with wavelength of observation, strong 2.3 micron CO absorption bands, and a large infrared excess. The 1980 optical photometric minimum is interpreted as a dust condensation event in the outflowing wind of V1515 Cyg; the slow recovery from the minimum was caused by expansion of the dust cloud in the wind. It is suggested that dust formation occurred in material with a temperature of 500-700 K at a radial distance of (1-2) x 10 exp 15 cm from the mass-losing source. A mass-loss rate of (1-3) x 10 exp -5 solar masses per year can produce the conditions required for dust formation in the wind of V1515 Cyg.
A High-Efficiency Disc Format for a High-Density Digital Video Disc Recorder

Recently, various types of digital video disc recorders, based on the digital versatile disc (DVD) system, have been introduced into the market, and are growing in popularity and will be more so in the future. But the recording capacity of a DVD system is only 4.7 GB, and thus, it is not applicable for high-vision recording, in particular. The authors are now researching and developing a high-density digital video disc recorder for high-vision recording, using a 120 mm phase-change disc and a blue-laser diode. In this study, a high-efficiency disc format is proposed as an important common subject for ensuring the reliability of a high-density digital video disc recorder.
Ionization models of cosmic ray sources

In recent years, as supernova or pulsar theories of the origin of galactic cosmic rays (GCR) had problems in giving a simple and self-consistent picture of the cosmic ray sources, alternative models were proposed. These models start from the observation that the abundance biases of the GCR source with respect to ordinary galactic matter seem correlated with the atomic properties of the elements. This view is supported by the observation that the same features probably show up in solar cosmic rays. We briefly recall our coronal-type ionization model and discuss the relevant physical conditions. These conditions are likely to be encountered in common astrophysical sites. We tentatively consider the extent to which powerful eruptive stars (flare stars) could contribute to the supply of the GCR.
Investigation of metamaterials for terahertz frequency range

Metamaterials are artificial materials with unusual properties that do not exist in nature and basically could consist of subwavelength metallic patterns printed on dielectric substrate. In this paper, we present a theoretical and experimental investigations of metamaterials designed for THz applications. First, fishnet metamaterials which are composed with a thin dielectric material sandwiched between two metallic layers. Two techniques were used in order to fabricate our prototypes: double layer optical lithography and laser micromachining. We performed simulations and experiments using commercial software simulator based on finite element method (HFSS) and terahertz time domain spectroscopy THz- TDS respectively. A good agreement was reported between simulations and experiments while pointed out the dramatic influences of dielectric losses in the effective response.
Spectral analysis of coded digital signals by means of difference equation systems

A new method of spectral analysis for coded sequences is introduced. An autocorrelation function is expressed by a system of difference equations. A translation of the system into the frequency domain by a z transform enables an expression for a code spectrum to be obtained after a few simple algebraic transformations. As an example the HDBn code spectrum is evaluated.
Automated registration and orthorectification package for Landsat and Landsat-like data processing

Precise registration and orthorectification of remote sensing images are the basic processes for quantitative remote sensing applications, especially for multi-temporal image analysis. In this paper, we present an automated precise registration and orthorectification package (AROP) for Landsat and Landsat-like data processing. The Landsat and Landsat-like satellite images acquired from different sensors at different spatial resolutions and projections can be re-projected, co-registered, and orthorectified to the same projection, geographic extent, and spatial resolution using a common base image through a combined resampling strategy; this allows us to perform multi-temporal image analysis directly. This paper presents and tests the AROP package on Landsat and Landsat-like data. The package is now freely available from our research web site.
Miniaturized bidirectional optical subassembly using silicon optical bench with 45-deg micro-reflectors in short-reach 40-Gbit/s optical interconnects

Abstract. The development of a 4-channel×10-Gbits/s optical interconnect module based on a silicon optical bench (SiOB) is presented. The 4-channel vertical-cavity surface-emitting laser (VCSEL) and photo diode (PD) arrays are flip-chip assembled onto the pedestals of SiOB using Au/Sn solder bumps to form an SiOB-based bi-directional optical sub-assembly (BOSA) configuration. The optical coupling of VCSEL-to-multi-mode fiber (MMF) and MMF-to-PD without adding coupled optics is −5.2 and −2 dB, respectively. The wide alignment tolerances of 1-dB power variation for the transmitting and receiver parts to be ±15 μm are achieved. The clearly open 10-Gbits/s eye patterns of transmitting part as well as the 10−12-order bit error rate (BER) at the receiving part verify the proposed SiOB-based module is suitable for the application of 4-channel×10-Gbits/s optical interconnects.
a-Stratified Multistage Computerized Adaptive Testing

Computerized adaptive tests (CAT) commonly use item selection methods that select the item which provides maximum information at an examinees estimated trait level. However, these methods can yield extremely skewed item exposure distributions. For tests based on the three-parameter logistic model, it was found that administering items with low discrimination parameter (a) values early in the test and administering those with high a values later was advantageous; the skewness of item exposure distributions was reduced while efficiency was maintained in trait level estimation. Thus, a new multistage adaptive testing approach is proposed that factors a into the item selection process. In this approach, the items in the item bank are stratified into a number of levels based on their a values. The early stages ofa test use items with lower as and later stages use items with higher as. At each stage, items are selected according to an optimization criterion from the corresponding level. Simulation studies were performed to compare a-stratified CATs with CATs based on the Sympson-Hetter method for controlling item exposure. Results indicated that this new strategy led to tests that were well-balanced, with respect to item exposure, and efficient. The a-stratifiedCATs achieved a lower average exposure rate than CATs based on Bayesian or information-based item selection and the Sympson-Hetter method.
Hydraulic conductivity estimation in partially saturated soils using a full-Newton method

An iterative algorithm based on a full-Newton method for the estimation of the saturated hydraulic conductivity k from drainage experiments is presented. The water flow in the unsaturated zone is assumed to be described by Richards equation and the well-known van Genuchten constitutive model. The cost functional used for the parameter optimization is defined as the L2-error between the calculated pressure head values and the observed data at discrete points in the soil profile during the drainage process. The derivative of pressure head with respect to the parameter k is obtained as the solution of a differential equation with appropriate boundary and initial conditions. A Galerkin finite element procedure is used to obtain approximated solutions of the two differential problems involved in each iteration: the direct problem and the derivative of the functional. The algorithm was implemented in one-dimensional domains and used to estimate k in layered soils using both synthetically generated data and observed data from an experimental plot in the Azul River basin (Buenos Aires, Argentina). Numerical examples show that the proposed algorithm yields very good estimations of the saturated hydraulic conductivity and becomes a promising method for in situ estimation of this parameter. Copyright © 2007 John Wiley & Sons, Ltd.
Delay‐dependent guaranteed cost gain‐scheduling control of LPV state‐delayed systems

Delay‐dependent gain‐scheduling controller design problem is addressed for the linear parameter‐varying state‐delayed systems with time‐varying delays. By choosing a Lyapunov–Krakovskii functional, delay‐dependent conditions for the existence of guaranteed cost gain‐scheduling controller are obtained. Besides, an algorithm is also presented to solve resultant nonconvex matrix inequalities in terms of linear matrix inequalities. Finally, three numerical examples with simulations are illustrated in order to demonstrate the validity of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd.
Super multiview 3D display system using reflective vibrating scanner array

In this paper, we present a primitive system design of a super multi-view (SMV) 3-D display system based on a focused light array (FLA) concept using reflective vibrating scanner array (ViSA). The parallel beam scanning using a vibrating scanner array is performed by moving left and right an array of curvature-compensated mirrors or diamond-ruled reflective grating attached to a vibrating membrane. The parallel laser beam scanner array can replace the polygon mirror scanner which has been used in the SMV 3-D display system based on the focused light array (FLA) concept proposed by Kajiki at TAO (Telecommunications Advancement Organization). The proposed system has great advantages in the sense that it requires neither huge imaging optics nor mechanical scanning parts. Some mathematical analyses and fundamental limitations of the proposed system are presented. The proposed vibrating scanner array, after some modifications and refinements, may replace polygon mirror-based scanners in the near future.
Group C*-Algebras and the Spectrum of a Periodic Schrödinger Operator on a Manifold

The spectrum of the Laplacian or more generally of a Schrödinger operator on an open manifold may have possibly a complicated aspect. For example, a Cantor set in the real axis may appear as the spectrum even for an innocent looking potential on a standard Riemannian manifold (see J. Moser [10]). The fundamental result of the spectral theory of periodic Schrödinger operators, however, says that the picture of the spectrum of a Schrödinger operator on ℝn with a periodic potential is simple; indeed the spectrum consists of a series of closed intervals of the real axis without accumulation, separated in general by gaps outside the spectrum (see M. Reed and B. Simon [13] or M. M. Skriganov [15] for instance).
Electrically active defects in silica-filled epoxy as revealed by light emission analysis

Epoxy resins have long been used as the insulation of electrical systems. They are generally formulated with a dispersion of micro-fillers to improve thermal and mechanical properties. However, there are concerns about the possible influence of these fillers on the electric behaviour, especially on the long term ageing under functional stresses. At the loose interface between matrix and fillers, macro- and micro-voids in the resin can provide weak points that are difficult to detect using conventional spectroscopy. Light emission analysis from the material under electrical stress is an efficient way to reveal such electrically active defects since internal ionizing events would give rise to photon emission. A detailed analysis of the light emitted by silica-filled and unfilled epoxy samples is presented. The photon counting technique, spectral analysis and imaging give a firm basis to discuss the contributing emission processes to the detected signal. They reveal the existence of ionizing events into internal defects. The sensitivity of the optical method is order of magnitudes higher than the sensitivity of conventional partial discharge detection.
Sample Selection and the Choice of Estimator in Two-Way Stratified Populations

Abstract The paper studies the effect on variance of the method of sample selection and the choice of estimator in a two-way stratified population. Three methods of sampling, simple random and one and two-way stratified, are studied in conjunction with estimators which use no population information, one and two sets of marginal frequencies and cell frequencies. It is shown that whether the information in the population frequencies is used in the sample draw or in the estimator, the sampling variances are approximately the same. Hence efficiency can be associated with the method of sample selection and the estimator by the amount of population information used by each. Some of the estimators involve post-stratified weighting and hence are subject to biases and inflated variances by the occurrence of small (or zero) sample sizes in the strata; in addition, the comparisons made are unequally affected by small sample sizes, but they are valid for sample sizes large enough to make the ratio estimators become s.
A least-squares-based method for determining the ratio between two measured quantities

A numerical procedure to find the ratio between two measured quantities is discussed in the framework of the least-squares method with errors in both coordinates. Constant, as well as variable, amounts of statistical uncertainties are considered for each variable along their measured range. Analytical solutions for particular cases are given. The variance of the ratio is given as a closed analytical expression valid for the general case. Limiting cases of the presented results are compared with those obtained using classical least-squares expressions. A comparison with the weighted average method is also discussed.
Comparison and improvement of commonly applied statistical approaches for identification of plant species from IR spectra

Fourier transform infrared spectroscopy (FTIR) has been studied many times in the context of identification of plant, fungal and bacterial species. Infrared spectra are commonly analyzed using multivariate statistical methods such as cluster analysis (CA), principal component analysis (PCA), partial least squares analysis (PLS) and discriminant analysis (DA). In this study, a univariate statistical method for analysis of variance (ANOVA) was used to reduce the number of variables before applying the multivariate methods. Analyzing variables using ANOVA or a combination of ANOVA with CA produced better results. Here, experiments were carried out by performing ANOVA using the first derivative of the spectra instead of the original spectra or its second derivative because using the first‐derivative variables led to improved distinction between species. Different results were obtained by applying different validation methods. The leave‐one‐out validation method gave higher results than the validation‐with‐training and validation sample sets, thus indicating the non‐objectivity of the leave‐one‐out validation method. Copyright © 2010 John Wiley & Sons, Ltd.