Values Of Scale Factor Research Articles

Anisotropic bianchi V cosmological model in Scale Covariant Theory of Gravitation with a time-variable deceleration parameter

In this paper we solve the field equations for Scale covariant theory of gravitation which was introduced by Caunato et al. [1], for Bianchi V line element in the presence of perfect fluid medium. Here the deceleration parameter is considered to be time dependent which gives the average scale factor a(t)=[sinh⁡(βt)]1/n, where n and β are positive constants. This value of average scale factor is the key expression for solving the field equations. Using the recent observational value of q0=−0.52−0.04+0.08 and H0=69.2±1.2 derived from BAO/CMB and H(z) data by Santos et al. (2016) [46], we have evaluated three different pairs of (n,β). We observe that the model represents a phase transition from early deceleration to a present accelerating phase for a particular choice of the pair (n=2,β=92.75). Applying some recently developed diagnostic tools like jerk parameter and statefinders, we find that the derived model is exactly in accordance with standard ΛCDM model. Along with these, many physical, geometric and kinematic properties of the model are thoroughly studied and found consistent with recent observations.

Correlations Between the Scaling Factor and Fitness Values in Differential Evolution

Correlations Between the Scaling Factor and Fitness Values in Differential Evolution

Source Consistency Electrical Impedance Tomography

In electrical impedance tomography (EIT), multiple electrodes are attached around an imaging domain such as the human thorax to inject currents and measure induced boundary voltages. Using the measured boundary voltage data, cross-sectional images of an internal conductivity distribution are reconstructed. Taking advantage of its fast temporal resolution, time-difference EIT can be used for image-based monitoring of physiological functions such as lung ventilation and cardiac blood flow. Among numerous data collection protocols, we assume current injections and voltage measurements between adjacent pairs of electrodes. The measured voltage difference between the $j$th electrode pair subject to the current injection between the $k$th electrode pair, for example, changes with time and its time-series is called a voltage channel in this paper. Investigating shapes of voltage channels, a new technique called source consistency EIT (scEIT) is proposed to extract voltage channel data originating from a physiological function or source of interest. The proposed scEIT technique suggests each voltage channel can be expressed up to a scale factor and offset value from a single shape-reference voltage channel when there exists only one time-varying source. When multiple physiological sources exist to concurrently produce correspondingly different conductivity changes, measured voltage channels are influenced by all of the sources. Using the scEIT method, each voltage channel can be expressed as a weighted sum of multiple shape-reference voltage channels of the sources. The proposed scEIT technique is verified through numerical simulations and animal experiments. Future experimental studies of applying the scEIT technique to in vivo human experiments are proposed.

Estimation of Wind Energy Potential for Two Locations in North-East Region of Nigeria

This paper presents an estimation of wind power potential of North East, Nigeria (Bauchi and Maiduguri) on the basis of monthly wind speed data at 10m height from the ground. The data for the locations were collected from Nigeria metrological station, Abuja for the period of (2013-2017). Mean monthly values were used in calculation of Weibull distribution parameters c (scale factor ms-1) and k (shape factor). The Weibull results shows that for Bauchi, the shape factor ranges from 2.86 – 5.96 and scale factor ranges from 2.32ms-1 – 2.54ms-1 while Maiduguri the shape factor ranges from 2.66 – 5.52 and values of scale factor ranges from 4.74ms-1 – 5.89ms-1. It is evident that the maximum average monthly value of wind speed in Bauchi occurs in year 2017 with value of 3.8ms-1 in the month of May while the maximum average wind speed in Maiduguri occurs in year 2013 with value of 8.5ms-1 in the month of December. The probability distribution function f(V) of wind speed, together with the duration function T(V) was evaluated for the period under investigation. From the statistical analysis of distributions, the Weibull distribution was found to have better fittings in the probability distribution functions f(V) and T(V). The value of power density was computed to be 33.47W/m2 (class I) & 374.62W/m2 (class II) and energy density was also computed to be 24.9 kWh/m2 & 278kWh/m2 for both Bauchi and Maiduguri respectively.

Equivalent number of uniform cycles versus earthquake magnitude relationships for fine-grained soils

In current geotechnical seismic design practice, the empirical correlation between equivalent number of uniform cycles (Neq) of shaking and earthquake magnitude (Mw) forms an integral part of liquefaction potential evaluation. This relationship, in turn, is used to derive the magnitude scaling factors that are commonly used in field-based liquefaction evaluation procedures. The Neqversus Mwrelationship for liquefaction assessment was examined for fine-grained soils using time-histories in the range 5 < Mw≤ 9, especially including strong ground motion time-histories from the latest subduction zone earthquakes with Mw> 8.0. The experimental database available from cyclic direct simple shear tests conducted on natural fine-grained soils retrieved from undisturbed soil sampling was used to obtain the cyclic shear resistance weighting curves for the study. The work presented herein has contributed to further improving the current models used to represent magnitude scaling factor (MSF) values for large earthquake magnitudes and the functional dependency of this parameter on soil type. The MSF–Mwcurve derived for low-plastic Fraser River Delta silt lies in-between the MSF curves derived for clean sand and clay, resonating with the inferences that have been made that the silt behavior can neither be considered sand-like nor clay-like.

Scale Factor Effect in Terrestrial Laser Scanner Datum Transformation

Datum transformation is an inevitable procedure in terrestrial laser scanners (TLSs) pre-processing. By taking into account the uncertainties in multi distances measurement, neglecting the scale factor in registration and georeferencing phases should be reconsidered especially when involved with applications that demand high accuracy data. With the motivation to robustly examine the effect of scale factor in the issue raised, this study has designed experiment which consider the element of multi distances. Two types of TLSs utilised in this study, which are Faro Focus 3D and Leica ScanStation C10 to represent phase and pulse based scanners, respectively. Exploiting robust statistical analysis, all seven (7) parameters were computed from both experiments and scale factors were extracted for the further assessment. Significant analysis was performed by comparing the ideal value of scale factor (i.e. 1.000 or no scale effect) and values obtained from the experiments. The results show that, the null hypotheses for the experiment is accepted with a 95% confidence level. This result also indicates that scale factor can be neglected in datum transformation process for both type of terrestrial laser scanners.

Modified Single Propagation Unscented Kalman Filter

When using single-point spread unscented Kalman filter, it is found that there may be large errors in estimating Jacobian matrix model with constant, resulting in poor estimation accuracy and even divergence. An improved single-point propagation unscented Kalman filter algorithm is proposed to solve this problem. By introducing the scaling factor, the influence of large distance between sampling points on the center point is reduced. Furthermore, the estimation accuracy and robustness of the single-point spread unscented Kalman filter algorithm are improved. In the simulation experiment, the ungm model is estimated. The performance of the single-point spread unscented Kalman filter, the unscented Kalman filter and the extended Kalman filter with different scaling factors are compared. A better scaling factor value is obtained. The improved algorithm is used to solve the measured data of indoor positioning, which proves the effectiveness of the algorithm.

Holographic bounce

We investigate the bounce realization arising from the application of the holographic principle in the early universe, inspired by its well-studied late-time application. We first consider as Infrared cutoffs the particle and future event horizons, and we show that the decrease of the horizons at early times naturally increases holographic energy density at bouncing scales, while we additionally obtain the necessary null energy condition violation. Furthermore, adding a simple correction to the horizons due to the Ultraviolet cutoff we analytically obtain improved nonsingular bouncing solutions, in which the value of the minimum scale factor is controlled by the UV correction. Finally, we construct generalized scenarios, arisen from the use of extended Infrared cutoffs, and as specific examples we consider cutoffs that can reproduce F(R) gravity, and the bounce realization within it.

Role of Scaling Factor in Robust Digital Watermarking

Digital watermarking has been identified as an efficient tool to provide copyright authentication and protection of digital data. Robustness and Imperceptibility are the two key parameters in designing of watermarking system. It is always desired to design a watermarking system that provides excellent robustness to malicious attacks and the watermark is invisible to human eyes. The robustness and imperceptibility can be controlled by choosing an effective scaling factor. Scaling factor decides on the amount of insertion of watermark in the host image. Higher the value of scaling factor more visible the watermark will be in watermarked image, this leads to poor imperceptibility. However the increase in scaling factor leads to a more robust watermarking system. Finding a trade-off among both is the key issue of research in this area. This paper aims at describing the effect of selection of scaling factor on robustness and imperceptibility by taking different values of scaling factor during each watermarking process. The empirical analysis done in this work shows robustness can be improved at the cost of imperceptibility and vice-versa.

Backreaction of electromagnetic fields and the Schwinger effect in pseudoscalar inflation magnetogenesis

We study magnetogenesis in axionlike inflation driven by a pseudoscalar field $\phi$ coupled axially to the electromagnetic (EM) field $(\beta/M_{p})\phi F_{\mu\nu}\tilde{F}^{\mu\nu}$ with dimensionless coupling constant $\beta$. A set of equations for the inflaton field, scale factor, and expectation values of quadratic functions of the EM field is derived. These equations take into account the Schwinger effect and the backreaction of generated EM fields on the Universe expansion. It is found that the backreaction becomes important when the EM energy density reaches the value $\rho_{\rm EM}\sim (\sqrt{2\epsilon}/\beta)\rho_{\rm inf}$ ($\epsilon$ is the slow-roll parameter and $\rho_{\rm inf}$ is the energy density of the inflaton) slowing down the inflaton rolling and terminating magnetogenesis. The Schwinger effect becomes relevant when the electric energy density exceeds the value $\rho_{E}\sim \alpha_{\rm EM}^{-3} (\rho_{\rm tot}^{2}/M_{p}^{4})$, where $\rho_{\rm tot}=3H^{2}M_{p}^{2}$ is the total energy density and $\alpha_{\rm EM}$ is the EM coupling constant. For large $\beta$, produced charged particles could constitute a significant part of the Universe energy density even before the preheating stage. Numerically studying magnetogenesis in the $\alpha$-attractor model of inflation, we find that it is possible to generate helical magnetic fields with the maximal strength $10^{-15}\,{\rm G}$, however, only with the correlation length of order $1\,{\rm pc}$ at present.

Quantum incompleteness of inflation

Inflation is most often described using quantum field theory (QFT) on a fixed, curved spacetime background. Such a description is valid only if the spatial volume of the region considered is so large that its size and shape moduli behave classically. However, if we trace an inflating universe back to early times, the volume of any comoving region of interest -- for example the present Hubble volume -- becomes exponentially small. Hence, quantum fluctuations in the trajectory of the background cannot be neglected at early times. In this paper, we develop a path integral description of a flat, inflating patch (approximated as de Sitter spacetime), treating both the background scale factor and the gravitational wave perturbations quantum mechanically. We find this description fails at small values of the initial scale factor, because \emph{two} background saddle point solutions contribute to the path integral. This leads to a breakdown of QFT in curved spacetime, causing the fluctuations to be unstable and out of control. We show the problem may be alleviated by a careful choice of quantum initial conditions, for the background and the fluctuations, provided that the volume of the initial, inflating patch is larger than $\gg H^{-1}$ in Planck units with $H$ the Hubble constant at the start of inflation. The price of the remedy is high: not only the inflating background, but also the stable, Bunch-Davies fluctuations must be input by hand. Our discussion emphasizes that, even if the inflationary scale is far below the Planck mass, new physics is required to explain the initial quantum state of the universe.

Construction of methods for determining the contours of objects on tonal aerospace images based on the ant algorithms

A method has been proposed for determining contours of objects on tonal aerospace images based on ant algorithms. The method, in contrast to those already known, takes into consideration patterns in the image formation; the ant algorithm is used for determining the contours. Determining an object's contours in the image has been reduced to calculating the fitness function, the totality of agents' motion areas, and the pheromone concentration along agents' motion routes. We have processed a tonal image for determining the contours of objects using a method based on the ant algorithm. In order to reduce the number of junk objects, the main principles and stages of the method for multi-scale processing of aerospace images based on the ant algorithm have been outlined. Determining the contours on images with a different value of the scale factor is carried out applying a method based on the ant algorithm. In addition, we rescale images with a different scale factor value to the original size and calculate the image filter. The resulting image is a pixelwise product of the original image and the image filter. The multiscale processing of tonal aerospace images with different scale values has been performed using methods based on the ant algorithms. It was established that application of a multi-scale processing reduces the number of junk objects. At the same time, due to multi-scale processing, not the objects' contours are determined but the objects in full. We estimated errors of first and second kind in determining the contours of objects on tonal aerospace images based on the ant algorithms. It was established that using the constructed methods has made it possible to reduce the first and second kind errors in determining the contours on tonal aerospace images by the magnitude of 18–22 % on average

Significant Study of Scale Factor in Phase-based Terrestrial Laser Scanner Datum Transformation

Rapid, direct and dense three-dimensional (3D) data acquisitions have become compulsory requirement for most applications that demand complete 3D information. Though, it is impossible to obtain data that cover the whole surface of the object from single sensor position. In terrestrial laser scanner (TLS) measurement, this multi positions issue was resolved using similarity transformation. However, only six (6) parameters were employed while scale factor was neglected. Since TLS measurement were utilised in many applications especially that demand high accuracy data, thus, further study is necessity to ensure the significant of neglecting scale factor in TLS datum transformation. Utilising robust experiment which involves with multi network configurations and multi distances, all seven (7) parameters were computed and scale factors were extracted for the further assessment. Significant analysis was performed by comparing the ideal value of scale factor (i.e. 1) and values obtained from the experiments. Results obtained for all configurations have accepted null hypothesis which indicates that scale factor is not significant in phase-based scanner datum transformation.

Study of QCD generalized ghost dark energy in FRW universe

A phenomenological generalized ghost dark energy model has been studied under the framework of FRW universe. In ghost dark energy model the energy density depends linearly on Hubble parameter (H) but in this dark energy model, the energy density contains a the sub-leading term which is depends on mathcal {O} (H^2), so the energy density takes the form rho _D=alpha H+ beta H^2, where alpha and beta are the constants. The solutions of the Friedman equation of our model leads to a stable universe. We have fitted our model with the present observational data including Stern data set. With the help of best fit results we find the adiabatic sound speed remains positive throughout the cosmic evolution, that claims the stability of the model. The flipping of the signature of deceleration parameter at the value of scale factor a=0.5 indicates that the universe is at the stage of acceleration i.e. de Sitter phase of the universe at late time. Our model shows that the acceleration of the universe begin at redshift z_{ace}approx 0.617 and the model is also consistent with the current observational data.

Dark sector unifications: Dark matter-phantom energy, dark matter - constant w dark energy, dark matter-dark energy-dark matter

The paper brings a novel approach to unification of dark matter and dark energy in terms of a cosmic fluid. A model is introduced in which the cosmic fluid speed of sound squared is defined as a function of its equation of state (EoS) parameter. It is shown how logarithmic part of this function results in dynamical regimes previously not observed in cosmic fluid models. It is shown that in a particular dynamical regime the model behaves as a unification of dark matter and phantom dark energy. Further, it is shown that the model may describe dark matter - dark energy unification in which dark energy asymptotically behaves as dark energy with a constant EoS parameter larger than −1. In a specific parameter regime the unified fluid model also reproduces global expansion similar to ΛCDM model with fluid speed of sound vanishing for small scale factor values and being small, or even vanishing, for large scale factor values. Finally, it is shown how the model may be instrumental in describing the cosmic fluid dark matter-dark energy-dark matter unification. Physical constraints on model parameters yielding such transient dark energy behavior are obtained.

МЕТОД БАГАТОМАСШТАБНОГО ОБРОБЛЕННЯ ЗОБРАЖЕНЬ З БОРТОВИХ СИСТЕМ ОПТИКО-ЕЛЕКТРОННОГО СПОСТЕРЕЖЕННЯ ДЛЯ ВИЗНАЧЕННЯ ЕЛЕМЕНТІВ МІСЬКОЇ ІНФРАСТРУКТУРИ

Предметом вивчення в статті є метод багатомасштабного оброблення зображень з бортових систем оптикоелектронного спостереження для визначення елементів міської інфраструктури. Метою є розробка методу багатомасштабного оброблення зображень з бортових систем оптико-електронного спостереження для визначення елементів міської інфраструктури. Завдання: аналіз відомих методів оброблення багатомасштабної послідовності зображень, розробка методу багатомасштабного оброблення зображень з бортових систем оптико-електронного спостереження для визначення елементів міської інфраструктури, проведення оброблення зображення з бортової системи оптико-електронного спостереження. Використовуваними методами є: методи теорії імовірності, математичної статистики, методи оптимізації, математичного моделювання та цифрової обробки зображень, методи математичної логіки. Отримані такі результати. Встановлено, що відомі методи оброблення багатомасштабної послідовності зображень не можуть бути напряму застосовані до багатомасштабного оброблення зображень з бортових систем оптико-електронного спостереження. Запропоновано метод багатомасштабного оброблення зображень з бортових систем оптико-електронного спостереження для визначення елементів міської інфраструктури. В основі методу покладений двоетапний метод виділення об’єктів міської забудови на зображеннях бортових систем оптикоелектронного спостереження з використанням перетворення Хафа. Проведено оброблення зображення з бортової системи оптико-електронного спостереження методом багатомасштабного оброблення зображень з бортових систем оптико-електронного спостереження для визначення елементів міської інфраструктури. Висновки. Наукова новизна отриманих результатів полягає в наступному. Запропоновано метод багатомасштабного оброблення зображень з бортових систем оптико-електронного спостереження для визначення елементів міської інфраструктури. На відміну від відомих, передбачається використання двоетапного методу визначення елементів міської інфраструктури на зображеннях з різним значення масштабного коефіцієнта, перемасштабування оброблених зображень з різним значенням масштабного коефіцієнта до вихідного розміру та розрахунок зображення-фільтру, а результуюче оброблене зображення є попіксельним добутком вихідного зображення та зображення-фільтру.

Using High-Precision Multimeter Digitizer for High Short-Circuit Current Calibration

The calibration of transient current sensors is fundamental for the reliability of high currents short-circuit tests. The test can be performed with prospective or withstand current, and in both cases, the dynamic behavior of the current sensors has to be investigated, due to their influence on the scale factor (SF) value. The requirements of the IEC 62475 standard can be achieved with a calibration in transient conditions, performed with an approved reference measuring system. In this paper, a more accurate measuring system is presented, for the improvement of the Istituto Nazionale di Ricerca Metrologica high transient current measuring capability. The result is achieved by analyzing the performance in digitalization of a commercial Keysight (former Agilent) multimeter 3458A, with a custom algorithm that can also perform the calculation of Joule integral ( $I^{2}t$ ) on a given amount of time along the acquired signal. The objective of the research is the realization of a measurement system with an uncertainty compatible with the test laboratory requirements, both for the determination of SF and evaluation of the performance in the measurement of $I^{2}t$ in the device under calibration.

Anisotropic n-dimensional quantum cosmological model with fluid

In the present work, we discuss the Wheeler–DeWitt quantization scheme for an n-dimensional anisotropic cosmological model with a perfect fluid in presence of a massless scalar field. We identify the time parameter using the generalization of Schutz formalism and find the wavepacket of the universe following standard Wheeler–DeWitt methodology of quantum cosmology. We also calculate the expectation values of scale factors and volume element. We show that quantized model escapes the singularity and supports bouncing universe solutions.

Brain Complexity in Children with Mild and Severe Autism Spectrum Disorders: Analysis of Multiscale Entropy in EEG.

Multiscale entropy (MSE) model quantifies the complexity of brain functions by measuring the entropy across multiple time-scales. Although MSE model has been applied in children with Autism spectrum disorders (ASD) in previous studies, they were limited to distinguish children with ASD from those normally developed without corresponding severity level of their autistic features. Therefore, we aims toexplore and to identify the MSE features and patterns in children with mild and severe ASD by using a high dense 64-channel array EEG system. Thisstudy is a cross-sectional study, where 36 children with ASD were recruited and classified into two groups: mild and severe ASD (18 children in each). Three calculated outcomes identified brain complexity of mild and severe ASD groups: averaged MSE values, MSE topographical cortical representation, and MSE curve plotting. Averaged MSE values of children with mild ASD were higher than averaged MSE value in children with severe ASD in right frontal (0.37 vs. 0.22, respectively, p=0.022), right parietal (0.31 vs. 0.13, respectively, p=0.017), left parietal (0.37 vs. 0.17, respectively, p=0.018), and central cortical area (0.36 vs. 0.21, respectively, p=0.026). In addition, children with mild ASD showed a clear and more increase in sample entropy values over increasing values of scale factors than children with severe ASD. Obtained data showed different brain complexity (MSE) features, values and topographical representations in children with mild ASD compared with those with severe ASD. As a result of this, MSE could serve as a sensitive method for identifying the severity level of ASD.

Scaling of the variance covariance matrix obtained from Bernese software

Global positioning system (GPS) refers positioning, timing and navigation services for different engineering applications. GPS positioning accuracies vary depending on the several parameters such as surveying method, data processing strategy and software packages. Bernese v5.2 software package is an important tool for processing and analyzing of the GPS measurements especially for the precise applications in scientific community. Although the accuracies of the estimated coordinates are sufficient, Variance–Covariance (VCV) matrices obtained from Bernese v5.2 are very optimistic because the correlations between different observables may be ignored by choosing identical weights for each measurement type in the analysis. This situation causes wrong interpretations for statistical analyses based on these VCV matrices. Therefore, the VCV matrices obtained from software should be scaled. In this study, the VCV matrices obtained from Bernese v5.2 were investigated for GPS measurements to estimate appropriate scale factor (SF) values. Baselines whose lengths ranging from 55 to 268 km and session durations between 2 and 24 h were processed with single baseline strategy for 31 consecutive days. According to the results, SF values do not depend on baseline lengths; but they vary depending on the session durations. A logarithmic function was defined for time-dependent SF values. This function has been tested in deformation analysis at the global test step and the obtained results, when the SF values are taken into account, are more reliable than the results when the unscaled VCV matrices are implemented.