Distortion Parameters Research Articles

Observing the contour profile of a Kerr–Sen black hole

In this paper, the shadow and the corresponding naked singularity cast by a Kerr–Sen black hole are studied. It is found that the shadow of a rotating black hole would be a dark zone surrounded by a deformed circle, and the shadow is distorted more away from a circle when the black hole approaches the extremal case. Besides, it is shown that the mean radius of the shadow decreases and distortion parameter increases with the increasing of charge, respectively. However, the mean radius and the distortion parameter vary complicatedly with the change of spin parameter. In the beginning, both observables decrease rapidly with the increasing of specific angular momentum, nevertheless, they increase slightly in the latter part. These results show that there would be a significant effect of the spin on the shadows, which would be of great importance for probing the nature of the black hole.

Linearity Distortion Analysis of Junctionless Quadruple Gate MOSFETs for Analog Applications

This paper examines a Junctionless quadruple gate (JLQG) MOSFET for analog and linearity distortion performance by numerically calculating transconductance and its higher order derivatives (gm1, gm2and gm3), VIP2, VIP3, IIP3 and IMD3. Influence of various physical device parameters: channel length, height (or width), gate oxide thickness, and channel doping concentration on the linearity distortion parameters are analyzed. From the numerical calculations it has been shown that the desirable characteristics for analog application at a given technology node are obtained for higher values of tSi, tox, and Nd. The present analysis also reveals the guidelines for the design of JLQG MOSFETs with least linearity distortion.

Nonlinear Frequency-Sweep Correction of Tunable Electromagnetic Sources.

Tunable electromagnetic (EM) sources, such as voltage-controlled oscillators, micro-electromechanical systems, or diode lasers are often required to be linear during frequency-sweep modulation. In many cases, it might also be sufficient that the degree of the nonlinearity can be well controlled. Without further efforts, these conditions are rarely achieved using free-running sources. Based on a predistortion voltage ramp, we develop in this paper a simple and universal method that minimizes the nonlinear frequency response of tunable EM sources. Using a current-driven quantum cascade laser as an example, we demonstrate that the nonlinearity can easily be reduced by a factor of ten when using a single distortion parameter . In the investigation of the IR absorption spectrum of ozone at 10 , an even better reduction of the frequency-scale error by two orders of magnitude is obtained by using the predistortion method to generate an essentially purely quadratic sweep frequency dependence that can be inverted easily to retrieve precise molecular line positions. After having tested our method on a variety of EM sources, we anticipate a wide range of applications in a variety of fields.

Temperature and pressure dependence of local structural changes around Gd3+ centers in RAl3(BO3)4 crystals: Modeling zero-field splitting parameters

The semi-empirical superposition model (SPM) analysis is applied to predict the zero-field splitting parameters (ZFSPs) of Gd3+ ions doped into RM3(BO3)4 (RAB) as well as the structural changes around these paramagnetic centers located at possible cation sites in these crystals. Theoretical investigations are aimed at explanation of the temperature dependence of the local structural parameters of Gd3+:RAB (R = Y, Eu, Tm). The results of spin Hamiltonian (SH) analysis of electron magnetic resonance (EMR; EPR – electron paramagnetic resonance) spectra serve for fine-tuning the theoretically predicted zero-field splitting (ZFS) parameters (ZFSPs) obtained using SPM. This approach enables determination of the local structure changes around Gd3+ centers in RAB crystals and explains the observed temperature dependence of the ZFSPs. For Gd3+:EuAB, due to availability of the data, also the observed pressure dependence of the ZFSPs is considered. For this purpose, the distortions parameters, i.e.m the changes in the ligand’s distances ΔRi and the angular distortions Δθi, have been treated as variable parameters in SPM analysis. This procedure yields good matching of the calculated ZFSPs and the experimental ones, and enables determination of the corresponding local distortions. The present results may be useful in future studies aimed at technological applications of the Huntite-type borates with the formula RM3(BO3)4. The model parameters determined here may be utilized for ZFSP calculations for Gd3+ ions at octahedral sites in single-molecule magnets and single-chain magnets.

Estimation of geometrical shapes of mass-formed nuclei (A=102-178) from the calculation of deformation parameters for two elements (Sn & Yb)

The present research focused on the studying of even- even nuclei forms for elements with mass numbers greater than 100 (A > 100) for isotopes. Which included the study of deformation parameters (β2) derived from the Reduced Electric Transition Probability B(E2) ↑ based on the energy of the first Excited State (2+), and distortion parameter (δ) from Intrinsic Electric Quadrupole Moments (Q0). Roots Mean Square Radii < r2 >1/2 were also calculated and compared with theoretical values. The diversity of nuclei forms for selected isotopes and their differences was observed by plotting three-dimensional shapes (axially symmetric) in addition to drawing two-dimensional shapes of single element isotopes to distinguish between them by using semi-major (a) and semi minor (b) axes.

The triply-ionized carbon forest from eBOSS: cosmological correlations with quasars in SDSS-IV DR14

We present measurements of the cross-correlation of the triply-ionized carbon (CIV) forest with quasars using Sloan Digital Sky Survey Data Release 14. The study exploits a large sample of new quasars from the first two years of observations by the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). The CIV forest is a weaker tracer of large-scale structure than the Lyα forest, but benefits from being accessible at redshifts z<2 where the quasar number density from eBOSS is high. Our data sample consists of 287,651 CIV forest quasars in the redshift range 1.4<z<3.5 and 387,315 tracer quasars with 1.2<z<3.5. We measure large-scale correlations from CIV absorption occuring in three distinct quasar rest-frame wavelength bands of the spectra referred to as the CIV forest, the SiIV forest and the Lyα forest. From the combined fit to the quasar-CIV cross-correlations for the CIV forest and the SiIV forest, the CIV redshift-space distortion parameter is βCIV=0.27 −0.14 −0.26 +0.16 +0.34 and its combination with the CIV linear transmission bias parameter is bCIV(1+βCIV)=−0.0183 −0.0014 −0.0029 +0.0013 +0.0025 (1σ and 2σ statistical errors) at the mean redshift z=2.00. Splitting the sample at z=2.2 to constrain the bias evolution with redshift yields the power-law exponent γ=0.60±0.63, indicating a significantly weaker redshift-evolution than for the Lyα forest linear transmission bias. Additionally, we demonstrate that CIV absorption has the potential to be used as a probe of baryon acoustic oscillations (BAO). While the current data set is insufficient for a detection of the BAO peak feature, the final quasar samples for redshifts 1.4<z<2.2 from eBOSS and the Dark Energy Spectroscopic Instrument (DESI) are expected to provide measurements of the isotropic BAO scale to ∼7% and ∼3% precision, respectively, at z≃1.6.

Quadratic distortion in a nonlinear cascade model of the human cochlea.

The cascade of asymmetric resonators with fast-acting compression (CARFAC) is a cascade filterbank model that performed well in a comparative study of cochlear models, but exhibited two anomalies in its frequency response and excitation pattern. It is shown here that the underlying reason is CARFAC's inclusion of quadratic distortion, which generates DC and low-frequency components that in a real cochlea would be canceled by reflections at the helicotrema, but since cascade filterbanks lack the reflection mechanism, these low-frequency components cause the observed anomalies. The simulations demonstrate that the anomalies disappear when the model's quadratic distortion parameter is zeroed, while other successful features of the model remain intact.

THERMAL EFFECTS ON CAMERA FOCAL LENGTH IN MESSENGER STAR CALIBRATION AND ORBITAL IMAGING

Abstract. We analyse images taken by the MErcury Surface, Space ENviorment, GEochemistry, and Ranging (MESSENGER) spacecraft for the camera’s thermal response in the harsh thermal environment near Mercury. Specifically, we study thermally induced variations in focal length of the Mercury Dual Imaging System (MDIS). Within the several hundreds of images of star fields, the Wide Angle Camera (WAC) typically captures up to 250 stars in one frame of the panchromatic channel. We measure star positions and relate these to the known star coordinates taken from the Tycho-2 catalogue. We solve for camera pointing, the focal length parameter and two non-symmetrical distortion parameters for each image. Using data from the temperature sensors on the camera focal plane we model a linear focal length function in the form of f(T) = A0 + A1 T. Next, we use images from MESSENGER’s orbital mapping mission. We deal with large image blocks, typically used for the production of a high-resolution digital terrain models (DTM). We analyzed images from the combined quadrangles H03 and H07, a selected region, covered by approx. 10,600 images, in which we identified about 83,900 tiepoints. Using bundle block adjustments, we solved for the unknown coordinates of the control points, the pointing of the camera – as well as the camera’s focal length. We then fit the above linear function with respect to the focal plane temperature. As a result, we find a complex response of the camera to thermal conditions of the spacecraft. To first order, we see a linear increase by approx. 0.0107 mm per degree temperature for the Narrow-Angle Camera (NAC). This is in agreement with the observed thermal response seen in images of the panchromatic channel of the WAC. Unfortunately, further comparisons of results from the two methods, both of which use different portions of the available image data, are limited. If leaving uncorrected, these effects may pose significant difficulties in the photogrammetric analysis, specifically these may be responsible for erroneous longwavelength trends in topographic models.

Exploring cosmic origins with CORE: Effects of observer peculiar motion

We discuss the effects on the cosmic microwave background (CMB), cosmic infrared background (CIB), and thermal Sunyaev-Zeldovich effect due to the peculiar motion of an observer with respect to the CMB rest frame, which induces boosting effects. After a brief review of the current observational and theoretical status, we investigate the scientific perspectives opened by future CMB space missions, focussing on the Cosmic Origins Explorer (CORE) proposal. The improvements in sensitivity offered by a mission like CORE, together with its high resolution over a wide frequency range, will provide a more accurate estimate of the CMB dipole. The extension of boosting effects to polarization and cross-correlations will enable a more robust determination of purely velocity-driven effects that are not degenerate with the intrinsic CMB dipole, allowing us to achieve an overall signal-to-noise ratio of 13; this improves on the Planck detection and essentially equals that of an ideal cosmic-variance-limited experiment up to a multipole ℓ≃2000. Precise inter-frequency calibration will offer the opportunity to constrain or even detect CMB spectral distortions, particularly from the cosmological reionization epoch, because of the frequency dependence of the dipole spectrum, without resorting to precise absolute calibration. The expected improvement with respect to COBE-FIRAS in the recovery of distortion parameters (which could in principle be a factor of several hundred for an ideal experiment with the CORE configuration) ranges from a factor of several up to about 50, depending on the quality of foreground removal and relative calibration. Even in the case of ≃1 % accuracy in both foreground removal and relative calibration at an angular scale of 1̂, we find that dipole analyses for a mission like CORE will be able to improve the recovery of the CIB spectrum amplitude by a factor ≃ 17 in comparison with current results based on COBE-FIRAS. In addition to the scientific potential of a mission like CORE for these analyses, synergies with other planned and ongoing projects are also discussed.

Accurate millimetre and submillimetre rest frequencies for cis- and trans-dithioformic acid, HCSSH

Context. A better understanding of sulphur chemistry is needed to solve the interstellar sulphur depletion problem. A way to achieve this goal is to study new S-bearing molecules in the laboratory, obtaining accurate rest frequencies for an astronomical search. We focus on dithioformic acid, HCSSH, which is the sulphur analogue of formic acid. Aims. The aim of this study is to provide an accurate line list of the two HCSSH trans and cis isomers in their electronic ground state and a comprehensive centrifugal distortion analysis with an extension of measurements in the millimetre and submillimetre range. Methods. We studied the two isomers in the laboratory using an absorption spectrometer employing the frequency-modulation technique. The molecules were produced directly within a free-space cell by glow discharge of a gas mixture. We measured lines belonging to the electronic ground state up to 478 GHz, with a total number of 204 and 139 new rotational transitions, respectively, for trans and cis isomers. The final dataset also includes lines in the centimetre range available from literature. Results. The extension of the measurements in the mm and submm range lead to an accurate set of rotational and centrifugal distortion parameters. This allows us to predict frequencies with estimated uncertainties as low as 5 kHz at 1 mm wavelength. Hence, the new dataset provided by this study can be used for astronomical search.

A novel solution in the simultaneous deep optimization of RGB-D camera calibration parameters using metaheuristic algorithms

This article presents a novel method for estimating 19 parameters of RGB and depth camera calibration simultaneously. The proposed algorithm is based on applying metaheuristic methods for deep optimization and estimating all parameters of intrinsic, extrinsic, and lens distortions of cameras. This paper compares four metaheuristic algorithms, i.e. a genetic algorithm, particle swarm optimization, the colonial competitive algorithm, and the shuffled frog leaping algorithm, with a numerical algorithm called singular value decomposition. The proposed method does not need the initial estimation for optimization and it can avoid being trapped in local minima. By using nondirect estimation, we achieve middle computing matrices such as the homography matrix, which is used in the pinhole camera model. Both versions of Kinect sensors are used for the experimental evaluation. The mean square of the reprojection error criteria is defined as the objective function in the proposed algorithm. The experimental results show that the proposed method is more efficient and accurate than traditional numerical solutions.

Impact of large-scale tides on cosmological distortions via redshift-space power spectrum

Although the large-scale perturbations beyond a finite-volume survey region are not direct observables, these affect measurements of clustering statistics of small-scale (sub-survey) perturbations in the large-scale structure, compared with the ensemble average, via the mode-coupling effect. In this paper we show that the large-scale tides induced by scalar perturbations cause apparent anisotropic distortions in the redshift-space power spectrum of galaxies in a way depending on an alignment between the tides, the wavevector of small-scale modes and the line-of-sight direction. Using the perturbation theory of structure formation, we derive the $\textit{response}$ function of the redshift-space power spectrum to the large-scale tides. We then investigate the impact of the large-scale tides on estimation of cosmological distances and the redshift-space distortion parameter via the measured redshift-space power spectrum for a hypothetical large-volume survey, based on the Fisher matrix formalism. To do this, we treat the large-scale tides as a signal, rather than an additional source of the statistical errors, and show that a degradation in the parameter is restored if we can employ the prior on the rms amplitude expected for the standard cold dark matter (CDM) model. We also discuss whether the large-scale tides can be constrained at an accuracy better than the CDM prediction, if the effects up to a larger wavenumber in the nonlinear regime can be included.

Foci of chronic infection and vascular rigidity in persons of military age

The role of focal infection as a possible risk factor for development of atherosclerotic cardiovascular diseases is discussed quite intensively now. Estimated some parameters of vascular stiffness in young men of military age with the features of their infectious-inflammatory medical history by the type of foci of chronic infection. It is established that in young men with foci of chronic infection such indicators of vascular stiffness, as peripheral augmentation index, augmentation index, normalized to heart rate, and augmentation index of the aorta were significantly higher than in their peers with a positive history. The differences in the first two indicators have reached a reliable level. It should be emphasized the presence of more low blood pressure in the presence of foci of chronic infection , which eliminates the distortion parameters of vascular status, influenced by the tensile effect from the blood pressure in the time of the study. The obtained data clearly indicate the higher rigidity of the walls of the aorta and large arteries in young men under the influence of their foci of chronic infection. Some tendency to development of left ventricular dysfunction in young people with presence of chronic tonsillitis and other infectious and inflammatory diseases was also revealed. This dysfunction is expressed in reducing the maximum rate of growth of blood pressure and increasing the period of expulsion of the left ventricle. The presented results confirm the concept of lifelong formation of «infectious-inflammatory load» in terms of increasing vascular rigidity and subclinical changes in the functioning of the myocardium at young age, subject to the presence of a focal chronic infection. These data allow us to regard foci of chronic infection as another risk factor of atherosclerosis, which in turn requires consideration when carrying out the relevant preventive measures among young population in the process of health checkups.

Improved Thermoelectric Performance in Nonstoichiometric Cu2+δMn1-δSnSe4 Quaternary Diamondlike Compounds.

A novel quaternary Cu2MnSnSe4 diamondlike thermoelectric material was discovered recently based on the pseudocubic structure engineering. In this study, we show that introducing off-stoichiometry in Cu2MnSnSe4 effectively enhances its thermoelectric performance by simultaneously optimizing the carrier concentrations and suppressing the lattice thermal conductivity. A series of nonstoichiometric Cu2+δMn1-δSnSe4 (δ = 0, 0.025, 0.05, 0.075, and 0.1) samples has been prepared by the melting-annealing method. The X-ray analysis and the scanning electron microscopy measurement show that all nonstoichiometric samples are phase pure. The Rietveld refinement demonstrates that substituting part of Mn by Cu well maintains the structure distortion parameter η close to 1, but it induces obvious local distortions inside the anion-centered tetrahedrons. Significantly improved carrier concentrations are observed in these nonstoichiometric Cu2+δMn1-δSnSe4 samples, pushing the power factors to the theoretical maximal value predicted by the single parabolic model. Substituting part of Mn by Cu also reduces the lattice thermal conductivity, which is well interpreted by the Callaway model. Finally, a maximal thermoelectric dimensionless figure-of-merit zT around 0.60 at 800 K has been obtained in Cu2.1Mn0.9SnSe4, which is about 33% higher than that in the Cu2MnSnSe4 matrix compound.

스테리오 비젼에 기반한 어류 표면적과 부피 측정을 위한 실시간 영상 분리와 3D 좌표의 결정

This paper proposes the real-time image segmentation and determination of 3D coordinates for fish surface area and volume measurements based on stereo vision. The segmentation process is performed in real-time on the video frame. Complexity and computation time are reduced by segmenting hue and value feature spaces separately before combining result. Morphological erosion and morphological dilation are applied to remove any object pixels that are clustered as background pixels. Finally, image segmentation is obtained in the binary image of an object. A step-by-step approach to computing a binary image is applied to obtain segmentation image. The object is considered a fish on a platform with a known background color, a known geometric shape for the fish, and the stereo camera is in fixed position to capture an image. The objective of this paper is to obtain a simple but accurate 3D image that is capable of capturing the 3D coordinates values of the fish object. The followings are done for this task: First, the stereo camera is calibrated to collect its intrinsic parameters and distortion parameters correctly. Second, an image is captured by the camera, that is segmented in real-time to distinguish between the object’s destination and its surroundings. Finally, the object coordinates, surface area, and volume of the fish are measured. Experiment results show that the proposed method has good results in real-time segmentation, and shows different surface areas and volumes within about 6% and 5.3%, respectively.

Monoclinic-to-orthorhombic phase transition in Cu2(AsO4)(OH) olivenite at high temperature: strain and mode decomposition analyses

ABSTRACTA natural olivenite single crystal was submitted toin situhigh-temperature single-crystal X-ray diffraction from room temperature (RT) to 500°C. Unit-cell parameters were measured at regular intervals of 25°C, and complete datasets collected atT= 25, 50, 100, 150, 200, 250, 300, 400 and 500°C. Evolution of unit-cell parameters and structure refinements indicates that olivenite undergoes a structural phase transition fromP21/ntoPnnmat ~200°C, and eventually becomes isostructural with the other members of the olivenite-mineral group. Volume expansion with temperature is larger in the monoclinic phase – where it follows a non-linear trend – than in the orthorhombic one. Axial and volume expansion coefficients of the orthorhombic olivenite phase are positive and linear and similar to those of the other Cu-bearing member of the mineral family, namely libethenite, but rather different from those of the Zn-analogue arsenate adamite.Distortion of Cu polyhedra is quite high in the olivenite monoclinic phase at RT and goes towards a relative regularization with increasingTuntil the phase transition occurs. In the orthorhombic phase, no significant variation of the polyhedral distortion parameters is observed with increasing temperature, and maximum expansion is along thebdirection and governed by corner-sharing. Landau potential provides a good representation of the macroscopic changes associated with the phase transition, coupling between the strains and the order parameter is responsible for the nearly tricritical character of the transition.

Numerical simulation of horizontal propagation steady-state thermal blooming effect on laser beam with different intensity distribution

The horizontal propagation steady-state thermal blooming effects of laser beams with different intensity distributions, such as Gaussian beam, flat-top beam, and flat-top beam with center obscuration, have been investigated by numerical simulation. The impacts of the output power, the propagation distance, the beam diameter, and the wind velocity vertical to the propagation direction on the steady-state thermal blooming have been discussed for the above mentioned three kinds of beams. Furthermore, the steady-state thermal blooming induced Strehl ratio degradation and peak intensity offset versus the generalized thermal distortion parameter N after long-path horizontal propagation of laser beams with above mentioned three types of intensity distributions have been derived. The simulation results show that, for certain other parameters, the greater output power or longer propagation distance will induce the stronger thermal blooming, and the increment of the launch diameter or the convection wind velocity vertical to the propagation direction will weaken the thermal blooming oppositely. Furthermore, for laser beams with different intensity distributions, the impacts of the thermal blooming on the propagation are so different. Under the same generalized thermal distortion parameter N, the thermal blooming effect on the Gaussian beam is the most serious, followed by the flat-top beam, and flat-top beam with center obscuration is the smallest.

Adaptive Order Cross–Square–Hexagonal search and fuzzy tangential-weighted trade-off for H.264 in motion estimation

In recent years, various algorithms have been proposed to attain low computational complexity in motion estimation of the image sequence coding based on block matching. This paper presents an Adaptive Order Cross–Square–Hexagon (AOCSH) search algorithm, which employs a smaller cross-shaped pattern before the first step of a square pattern and replaces the square-shaped pattern with the hexagon search patterns in subsequent steps. The proposed search patterns aid in finding the best matching block, without much consideration of the vast number of search points. Here, fuzzy tangent-weighted function is also proposed to evaluate the matching points using the rate and the distortion parameters. The proposed methods are effectively applied to the block estimation process to handle the objectives of visual quality and distortion. The performance of the proposed AOCSH approach is compared to the existing methods, such as AOSH, H.264 and elastic models, using the structural similarity index (SSIM) and the peak signal to noise ratio (PSNR). From the analysis, it can be seen that the proposed approach attains the maximum SSIM of 0.99 and maximum PSNR of 40. 92 dB with reduced computation time of 3.28 s.

Understanding the Internal Magnetic Field Configurations of ICMEs Using More than 20 Years of Wind Observations

The magnetic topology, structure, and geometry of the magnetic obstacles embedded within interplanetary coronal mass ejections (ICMEs) are not yet fully and consistently described by in situ models and reconstruction techniques. The main goal of this work is to better understand the status of the internal magnetic field of ICMEs and to explore in situ signatures to identify clues to develop a more accurate and reliable in situ analytical models. We take advantage of more than 20 years of Wind observations of transients at 1 AU to compile a comprehensive database of ICMEs through three solar cycles, from 1995 to 2015. The catalog is publicly available at and is fully described in this article. We identify and collect the properties of 337 ICMEs, of which 298 show organized magnetic field signatures. To allow for departures from idealized magnetic configurations, we introduce the term “magnetic obstacle” (MO) to signify the possibility of more complex configurations. To quantify the asymmetry of the magnetic field strength profile within these events, we introduce the distortion parameter (DiP) and calculate the expansion velocity within the magnetic obstacle. Circular-cylindrical geometry is assumed when the magnetic field strength displays a symmetric profile. We perform a statistical study of these two parameters and find that only 35% of the events show symmetric magnetic profiles and a low enough expansion velocity to be compatible with the assumption of an idealized cylindrical static flux rope, and that 41% of the events do not show the expected relationship between expansion and magnetic field compression in the front, with the maximum magnetic field closer to the first encounter of the spacecraft with the magnetic obstacle; 18% show contractions (i.e. apparent negative expansion velocity), and 30% show magnetic field compression in the back. We derive an empirical relation between DiP and expansion velocity that is the first step toward improving reconstructions with possible applications to space weather studies. In summary, our main results demonstrate that the assumed correlation between expanding structure and asymmetric magnetic field is not always valid. Although 59% of the cases could be described by circular-cylindrical geometry, with or without expansion, the remaining cases show significant in situ signatures of departures from circular-cylindrical geometry. These results will aid in the development of more accurate in situ models to reconcile image.

Distortion risk measures for nonnegative multivariate risks

We apply distortion functions to bivariate survival functions for nonnegative random variables. This leads to a natural extension of univariate distortion risk measures to the multivariate setting. For Gini’s principle, the proportional hazard transform distortion and the dual power transform distortion, certain families of multivariate distributions lead to a straightforward risk measure. We show that an exact analytical expression can be obtained in some cases. We consider the independence case, the bivariate Pareto distribution and the bivariate exponential distribution. An illustration of the estimation procedure and the interpretation is also included. In the case study, we consider two loss events with a single risk value and monitor the two events together over four different periods. We conclude that the dual power transform gives more weight to the observations of extreme losses, but that the distortion parameter can modulate this influence in all cases. In our example, multivariate risk clearly diminishes over time.