Figure Of Merit Parameter Research Articles

Prediction of Crystal Size and Microstrain Using Artificial Neural Network From Gaussian Peak Shape Analysis of X-Ray Diffraction Data

X-ray diffraction (XRD) is a widely used technique in materials science to determine crystal structure, crystal size and peak shape of crystalline materials. However, the interpretation of XRD data is often challenging due to the complexity of the diffraction patterns and the presence of noise. In this study, we demonstrate the application of artificial neural networks (ANNs) to predict crystal size and peak shape from XRD data using the Gaussian function. ANNs are a powerful machine learning tool that can learn complex relationships between input and output variables. Our results suggest that ANNs can be a valuable tool for the interpretation of XRD data, especially when the diffraction patterns are complex or noisy. The average value of the crystal size is estimated and evaluated by the figure of merit parameter. This approach has potential applications in materials science, where accurate characterization of crystal structure and size is essential for understanding material properties and designing new materials.

Collective modes, relaxations, de Vries behavior and field influence in SmA and SmC*deVr phases of chiral liquid crystal dimer C-10Bms with siloxy spacer.

Investigations in chiral liquid crystal dimer with trisiloxy unit on spacer unit, viz. C-10Bms, are reported with respect to its resolved dipole moment. Occurrence of SmA and SmC*deVr LC phases was characterized by POM and DSC. Relatively enhanced thermal range of LC phases in dimer configuration was detailed. Tilt angle, hysteresis, polarization, collective modes and other low-frequency relaxations were investigated. Primary order parameter revealed validity of critical field model. Moderate tilt for viewing angle and electro-clinic response for switch speed in dimer were addressed. Hysteresis in SmC*deVr ensued storage capability for memories. Slightly higher activation energy Ea was attributed to siloxy chain on spacer. Goldstone and Soft modes were identified in SmC*deVr phase. Field influence on Goldstone mode was analyzed. Equivalence of thermal/Arrhenius and field activation energies was observed. Curie-Weiss law for SM revealed strong collective ferroelectric response. Temperature and field trends of dielectric relaxation parameters were addressed in terms of chiral center-based out-of-phase dipole moment. Figure of merit parameters in SmC*deVr estimated by dielectric loss revealed its relative performance far below the SmA-SmC*deVr phase transition.

A Linear Thermoelectricity Theory for Thermoelectric Materials

The governing equations of thermoelectricity are nonlinear in general. Herein, a first‐order linear theory of thermoelectricity for thermoelectric (TE) materials is presented, in which the Joule heating contribution is neglected in the energy balance equation as it is usually at least one order of magnitude smaller than the total thermal energy in TE generator applications. The first‐order linear theory is applied to calculate the energy conversion efficiency for homogeneous, functionally graded, and segmented TE generators under 1D heat flow conditions. Energy efficiency for a 2D example is also presented. It is found that the maximum energy efficiencies predicted by the linear theory agree well with those using the general nonlinear theory of thermoelectricity, which indicates that the linear theory is accurate in predicting the energy efficiencies of TE devices. Finally, the peak efficiency for a homogeneous leg under 1D conditions in the linear theory is also characterized by the figure of merit parameter Z as in the nonlinear theory.

High-temperature analysis of optical coupling using AlGaAs/GaAs LEDs for high-density integrated power modules

A low-temperature co-fired ceramic (LTCC)-based optocoupler design is demonstrated as a possible solution for optical isolation in high-density integrated power modules. The design and fabrication of LTCC based package are discussed. Commercially available aluminum gallium arsenide/gallium arsenide (AlGaAs/GaAs) double heterostructure is used both as emitter and photodetector in the proposed optocoupler. A detailed study on the electroluminescence and spectral response of the AlGaAs/GaAs structure is conducted at elevated temperatures. The material figure of merit parameter, D*, is calculated in the temperature range 77–800 K. The fabricated optocoupler is tested at elevated temperatures, and the results are presented.

Structural, optoelectronic, optical coating and thermoelectric properties of the chalcogenides type Kesterite Ag2CdSnX4 (with X=S, Se): A computational insight

To find a seemly solution to the problems of efficiency dependency of the hybrid PV/TE devices, on important factors like “high-absorbance with high-ZT materials” and improving the performance of existing devices, are essential research topics nowadays. In this regard, we report here optical coating, and thermoelectric features of the kesterite-structured Ag2CdSnS4 and Ag2CdSnSe4 compounds. These investigations are performed at the level of “full-potential linearized augmented plane wave plus local orbital method, FP-L(APW + lo)” framed within the “density functional theory (DFT)” method comprised with relativistic effects. Our study of the optical coating shows that both the investigated materials have a good level of absorbance (A), approximately 80% in the visible part of the spectra. Further, we found that the magnitude of reflectance (R) of the Ag2CdSnX4 (X = S, Se) thin films increase with increasing film thickness, while the response of the transmittance (T) spectra is reverse to it. These results are corroborated by the study of the transport properties by employing the Boltztrap code, and correspondingly electrical conductivity, Seebeck coefficient, electronic thermal conductivity as well as the figure of merit parameters were evaluated and analyzed as a function of the chemical potential for both investigated compounds at five values of the temperatures. Hence our obtained results show that both the investigated semiconductor materials exhibit strong potential for the application of hybrid PV/TE systems.

Theoretical analysis of annular thermoelectric generators made of functionally graded materials

In this study, the temperature field distribution and thermoelectric conversion efficiency of annular thermoelectric (TE) generators with functionally graded materials (FGMs) are investigated. The power series method is employed for solving a linear differential equation with variable coefficients to obtain temperature distribution, which has been proved to have good convergence and high precision. Numerical studies are carried out on FGM TE generators with linear and exponential variation, respectively. Material parameters that vary dependently and independently are discussed. If the figure of merit parameter Z keeps constant, then increases in the maximal conversion efficiency are not obvious. If material parameters vary independently, then the Seebeck coefficient increases from the cold temperature end to the hot temperature end and the maximal efficiency reaches 17.86%, which increases by 25.86% over 14.19% of homogeneous materials. For temperature-dependent TE materials, the problem could also be simplified to a functionally graded problem by presupposing an initial temperature field distribution. All these results give theoretical guidance for optimization of annular TE generators by using functionally graded structures.

Estimate half-life of thermoluminescence signals according to the different models by using Python

In this study, the half-life is the time required for the thermoluminescence intensity to drop to half of its initial value. The half-life is a characteristic of the optical and thermal properties of the material. The half-life of the thermoluminescence signals under other models such as first order kinetics, second order kinetics, general order kinetics, mixed order kinetics and the one-trap one-recombination was calculated. The specific goals of this work are to give the half-life difference of the thermoluminescence signal of each model by using Python. The formulas allow to quickly determine the half-life of the simulated or empirical thermoluminescence curve, including one or more complex peak. Simulation results and calculations based on the figure of merit parameters allow to check the calculation of the half-life according to the most suitable model.

A Design Technique for Optimizing Resonant Coils and the Energy Transfer of Inductive Links

Power transfer efficiency (PTE) is a key performance parameter in development work on resonant inductive power transfer (IPT) systems. Geometrically optimizing the transmitter (Tx) and receiver (Rx) coil pair is a way of improving the IPT system's efficiency. In this article, a new figure-of-merit (FoM) is proposed to find an optimum coil geometry which maximizes the PTE. The employed FoM parameter, called the “strong coupling factor” (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">scf</sub> ), is defined such that its value indicates how strongly the Tx and Rx coils are linked together. Considering the IPT application and its physical size constraints, a proper selection method for identifying the numerical value of P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">scf</sub> is essential for optimal coil geometry design. This article presents an iterative algorithm to assist in the selection of the most favorable P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">scf</sub> value which provides maximized PTE for the designed optimum coil geometry. Design examples of two nominal IPT systems at frequencies of 415 and 0.1 MHz are used to investigate the design algorithm. Theoretical calculations show the optimum geometry designed for the IPT system operating at 415 MHz, with coupling coefficient (K) of 0.2, can achieve maximum PTE of 85.70%. Measurements presented from a practical Tx/Rx coil pair in the IPT link operating at 0.1 MHz, with K = 0.05, show a PTE of 83.10% against a calculated PTE of 84.11% validating the design process.

Extreme and high synchrotron peak blazars beyond 4FGL: The 2BIGB γ-ray catalogue

ABSTRACT This paper presents the results of a γ-ray likelihood analysis over all the extreme and high synchrotron peak blazars (EHSP and HSP) from the 3HSP catalogue. We investigate 2013 multifrequency positions under the eyes of Fermi Large Area Telescope, considering 11 yr of observations in the energy range between 500 MeV and 500 GeV, which results in 1160 γ-ray signatures detected down to the TS=9 threshold. The detections include 235 additional sources concerning the Fermi Large Area Telescope Fourth Source Catalog (4FGL), all confirmed via high-energy TS (Test Statistic) maps, and represent an improvement of ∼25 per cent for the number of EHSP and HSP currently described in γ-rays. We build the γ-ray spectral energy distribution (SED) for all the 1160 2BIGB sources, plot the corresponding γ-ray logN−logS, and measure their total contribution to the extragalactic gamma-ray background, which reaches up to ∼33 per cent at 100 GeV. Also, we show that the γ-ray detectability improves according to the synchrotron peak flux as represented by the figure of merit parameter, and note that the search for TeV peaked blazars may benefit from considering HSP and EHSP as a whole, instead of EHSPs only. The 2BIGB acronym stands for ‘Second Brazil-ICRANet Gamma-ray Blazars’ catalogue, and all the broad-band models and SED data points will be available on public data repositories (OpenUniverse, GitHub, and Brazilian Science Data Center-BSDC).

Energy Efficiency of Anisotropic Thermoelectric Materials Under Three-Dimensional Conditions

The figure of merit parameter (Z) for an anisotropic thermoelectric (TE) material is dependent on direction, and the highest Z has been used to characterize the energy conversion efficiency of anisotropic TE materials. It is, however, not clear whether the material properties in other directions also play a role in the TE generator efficiency. This work presents a three-dimensional (3D) model to investigate the direction dependence of energy efficiency for orthotropic TE materials. It is analytically proved that the peak efficiency is a function of Z in the leg direction, the thermal conductivity (separate from that in Z) in the leg direction and the thermal conductivities in the lateral directions, but is independent of lateral electrical conductivities. Numerical examples indicate that the energy efficiency is insensitive to the lateral thermal conductivities, but increases with an increase in the thermal conductivity in the leg direction for a fixed Z in the leg direction. Moreover, the efficiency of an orthotropic material with the leg in a lower Z direction may become higher than that with the leg along the highest Z direction, depending on the thermal conductivity in the leg direction, which indicates that orienting the highest Z direction along the leg may not necessarily achieve the highest TE generator efficiency. The effects of anisotropy on the efficiency are coupled with heat loss along the lateral surface and become less significant for small surface heat transfer coefficients.

Performance assessment of Gr/Si/Gr UV-photodetector: Design and optimization of graphene interdigitated electrodes

In this paper, a new p-Si - MSM-UV -photodetector ( PD ) based on graphene interdigitated electrodes ( GrIE ) is proposed to achieve the dual role of enhanced time response and superior responsivity. An overall performance comparison between the proposed GrIE/p-Si- based MSM PD design and the conventional Au/p-Si structure is carried out using new comprehensive analytical models. The obtained results indicate the outstanding capability of the proposed design for improving the MSM PD performance. Such enhancement can be attributed to the suppressed degradation related-shadowing effects, where the use of graphene transparent electrodes open up the route for improving the device optical behavior. In order to address the trade-off between speed and photoresponse properties, a new Figure of Merit ( FoM ) parameter that combines both performance criteria is proposed. The impact of GrIE geometrical parameters on the device FoM is also analyzed. Moreover, Particle Swarm Optimization ( PSO ) approach is proposed to boost up the device performance. It is found that the optimized GrIE/p-Si design pinpoints a new path toward simultaneously reaching a high responsivity (770 mA/W) with reduced time response (3 μs). Therefore, the proposed design methodology not only outperforms the conventional Au/p-Si PD , but also enables bridging the gap between high-speed and ultrasensitive properties, making it suitable for high-performance sensing applications using 2D materials . • Performance assessment of a new Gr/Si/Gr UV-photodetector is carried out. • The proposed structure suppresses the degradation-related shadowing effects. • A new FoM parameter that combines both responsivity and speed properties is proposed. • The proposed photodetector exhibits improvement over the conventional structures.

Perturbation theory challenge for cosmological parameters estimation: Matter power spectrum in real space

We study the accuracy with which cosmological parameters can be determined from real space power spectrum of matter density contrast at weakly nonlinear scales using analytical approaches. From power spectra measured in $N$-body simulations and using Markov chain Monte-Carlo technique, the best-fitting cosmological input parameters are determined with several analytical methods as a theoretical template, such as the standard perturbation theory, the regularized perturbation theory, and the effective field theory. We show that at redshift 1, all two-loop level calculations can fit the measured power spectrum down to scales $k \sim 0.2 \, h \, \mathrm{Mpc}^{-1}$ and cosmological parameters are successfully estimated in an unbiased way. Introducing the Figure of bias (FoB) and Figure of merit (FoM) parameter, we determine the validity range of those models and then evaluate their relative performances. With one free parameter, namely the damping scale, the regularized perturbation theory is found to be able to provide the largest FoM parameter while keeping the FoB in the acceptance range.

Design and development of magnetic refrigeration prototype for the performance analysis of magnetocaloric materials

Magnetic refrigeration (MR) has been receiving an attention as an alternative system to conventional refrigeration based on vapor compression. Normally, the vapor compression uses hydrofluorocarbons (HFC) and Chlorofluorocarbons (CFC) as refrigerant fluids which damage ozone layers causing global warming. Consequently, the magnetic system has been developed to replace the traditional system to reduce global warming potential (GWP). The alternative cooling technology is based on the magnetocaloric effect (MCE) of magnetocaloric materials (MCM) which are able to change their temperature following magnetic flux density under magnetic field generator. The refrigeration is operated via an active magnetic regeneration (AMR) cycle with rotating magnets. In this work, the magnet assembly has been designed and studied with the aspiration for compact and efficiency. Based on extensive reviews, the magnet assembly model of Okamura et al. provides the conceptual design with optimal compactness and efficiency. Hence, in this study, the magnet assembly design has been developed based on the model by Okamura et al. The magnetic system consists of a soft magnetic composite stator and four neodymium (NdFeB) permanent magnets rotated by motor. The magnetic field performance of the assembly is analyzed using the COMSOL Multiphysics software. The generated magnetic flux density is 0.65 T provided by only 0.9 L of permanent magnets. In addition, the efficiency of the magnet design is represented by a figure of merit parameter, Λcool. Among others, the proposed design exhibit a high Λcool value of 0.17, which is as high as five times better than the magnet assembly designs by prior work.

Characteristics optimization in single and dual coupled silicon-on-insulator ring (disk) photonic biosensors

Silicon-on-insulator (SOI) evanescent field whispering gallery mode (WGM) ring (disk) sensors are promising components for biological sensing applications. We study the optimum design parameters that result in the highest sensitivity (S) and figure of merit (FOM) simultaneously, for single and dual coupled SOI WGM ring (disk) based sensors. These devices are respectively consisting of one and two silicon ring (disk) resonator coupled to a straight waveguide. Periodic behavior of coupling parameters in biological solutions, are modelled by analytical conformal transformation method and coupled mode theory. These methods are verified by experimental results. We demonstrate optimum design parameters at twelve different configurations of single SOI ring (disk) based sensors. Based on the results, the calculated quality factor of second TE WGM resonance at these resonators in water solutions is Qt ≥ 25000. This gives S and FOM parameters to be 193 (134) nm/RIU and 3112 (2161) /RIU, for single ring (disk) resonator sensor. We also obtain an ultra-improved intrinsic limit of detection (ILOD=7.32 × 10−8 RIU) biosensor based on two coupled ring resonators. The ILOD value, shows that our structure performs two and three orders of magnitude better than respectively two and three SOI cascade ring resonators based sensors, reported lately.

Influence of TCO intermediate thin-layers on the electrical and thermal properties of metal/TCO/p-Si Schottky structure fabricated via RF magnetron sputtering

In this paper, versatile Metal/TCO/p-Si Schottky Barrier Diodes (SBDs) with dissimilar TCO intermediate layers (ZnO and ITO) were fabricated by RF magnetron sputtering technique. An overall electrical performance comparison between the Al/ZnO/p-Si, Au/ITO/p-Si and the conventional Au/p-Si structures is carried out. The measured I-V characteristics indicate that the proposed Al/ZnO/p-Si design exhibits an outstanding capability for achieving a high rectifying ratio of 142 dB. This is mainly due to the enhanced Schottky barrier height (SBH) of 0.75 V and close to unite ideality factor (n = 1.23). Such behavior can be attributed to the enhanced interface quality achieved by introducing TCO inter-layers, which could decrease the Series resistance. A comparative study of the elaborated structures performance is carried out in which new Figures of Merit (FoM) parameters that combine both electrical and thermal stability performances are proposed. The Experimental results show that the proposed designs with ITO and ZnO sub-layers exhibits improved FoM parameters as compared to the conventional Au/p-Si structure. Moreover, this comparative study enables to the designer to acquire a comprehensive review about the Si-based SBDs design tradeoffs. It is demonstrated that the insertion of a TCO inter-layer might be beneficial for avoiding the degradation related-heating effects. Therefore, the proposed designs offer the possibility of bridging the gap between superior electrical performance and high thermal stability, which makes them suitable for developing high-performance Schottky solar cells and sensing applications.

Temperature Effects on the Resolution of Surface-Plasmon-Resonance-Based Sensor

The fluctuation of the ambient temperature during the sensing action may seriously affect the performance characteristics of optical sensors based on surface plasmon resonance (SPR). For example, at elevated temperature surface plasmons can be damped due to increased phonon–electron scattering in the metal. Owing to this, the SPR curve becomes broader and, hence, the resolution and sensitivity will be reduced. In this paper, we present a theoretical investigation of the effect of temperature changes on the resolution of SPR sensors. To estimate the resolution of the sensor, we propose to use the figure of merit parameter (FOM) with spectral modulation and data post-processing. We consider two types of configurations, Kretschmann configuration with silver thin film sandwiched between BK7 prism and water-sensing medium and a diffraction-grating-based configuration. We consider sensing action based on angular and wavelength modulations. The obtained results show that the figure of merit (FOMθ) depends strongly on the temperature and decreases with its increasing magnitude. However, with wavelength modulation, (FOMλ) is slowly decreasing with temperature.

Effective Non-Linear Prefiltering Method for Coloured Edge Detection of Noisy Images

This paper addresses a method to obtain color edge detection for images corrupted with Gaussian noise and impulse noise, to correctly reproduce distinct, continuous edges based on non-linear prefiltering followed by block-by-block rotations to locate the edges in all orientations. In this work our major goal is to eliminate the noise from noisy image as edges are the most important detailing areas in an image and addition of noise corrupt these edges which result in lack of clarity. In our proposed work we are proposing a efficient hybrid algorithm to preserve the edges of image based upon Canny operator. Our proposed scheme is based on rotation, median filtering and performing morphological thinning. This scheme is evaluated on basis of FOM(Figure Of Merit) parameter and our result are efficient than previous technique. This paper is divided into some sections.

Dramatically enhanced thermal properties for TiO2-based nanofluids for being used as heat transfer fluids in concentrating solar power plants

The paper presents an analysis of the properties of TiO2-based nanofluids such as their physical stability and heat transfer performance. The nanofluids were prepared with a eutectic mixture of diphenyl oxide and biphenyl with the addition of TiO2 nanoparticles and 1-octadecanethiol (ODT), used as a surfactant. The nanofluids were tested to determine their thermal and physical properties, such as stability, density, viscosity. The introduction of TiO2 nanoparticles accompanied with equal quantity of ODT was seen to sharply enhance the properties of the system in terms of heat transfer in concentrating solar power (CSP) plants. In particular, the system became stable after 3–5 days, and the settlement rate depended on the nanoparticle concentration. There was a slight increase in density and viscosity of no more than 0.12% and 4.85%, respectively. The thermal properties improved significantly, up to 52.7% for the isobaric specific heat and up to 25.8% for the thermal conductivity. The dimensionless Figure of Merit parameter (FoM), which is based on the Dittus-Boelter correlation, was used as a criterion for evaluating efficiency. At all the temperatures tested the nanofluid with 2.5·10−4 wt% (volume fraction of 2.44%) of TiO2 performed best, increasing the efficiency by up to 35.4% with regard to the pure heat transfer fluid (HTF) used in CSP plants. Thus, nanofluids based on TiO2 nanoparticles seem to be a promising alternative to HTFs in CSP plants.

Effects of resistivity on linear plasma responses to resonant magnetic perturbations in tokamak plasmas

Numerical studies are made of the effects of resistivity on linear plasma responses to resonant magnetic perturbations (RMPs) in tokamaks based on a reduced magnetohydrodynamic model. From a local two-field model, it is suggested that the ratio of the poloidal electron advection to the resistivity diffusion rate αm can be a figure of merit parameter in linear RMP penetration physics. The shielding efficiency is governed by αm, and when αm≳1, RMPs are effectively shielded. Global simulations using a four-field model [Hazeltine and Meiss, Phys. Rep. 121, 1 (1985)] show that there exists an effective threshold of the perpendicular electron flow (Ve,⊥c) beyond which RMPs cannot penetrate. Resistivity is found to determine Ve,⊥c which increases as resistivity becomes higher, making RMP penetration easier. At low resistivity, small Ve,⊥c renders the RMP penetration sensitive to ion collisionality and the change in q95. The kink response is observed to be closely related to the residual level of RMPs at rational surfaces and can be also strongly affected by resistivity.

Performance enhancement of a plasmonic structure comprising of indium oxide–zirconium dioxide–silver–zinc oxide intermediate layers working in visible and infrared wavelength region

Modeling of a fused silica ( SiO 2 ) glass prism-based plasmonic structure comprising of indium oxide ( In 2 O 3 )–zirconium dioxide ( ZrO 2 )–silver (Ag)–zinc oxide (ZnO) intermediate layers showing enhancement in sensitivity and figure-of-merit (FOM) in visible and infrared regime has been reported in this paper. Performance of the proposed plasmonic structure has been demonstrated in terms of sensitivity, half width (HW), detection accuracy (DA), and FOM parameters in visible (632.8 nm) and infrared (1200 nm) wavelength of light. High sensitivity of fused silica glass material, In 2 O 3 , ZnO films along with high DA and high FOM of Ag and inclusion of ZrO 2 as an oxidation protective layer in between In 2 O 3 and Ag have been the most exciting and advantageous features of our proposed structure. Simulated sensitivity values of our proposed structure were found to be 73.8 deg/RIU at 632.8 nm wavelength and it was found enhanced to 109.6 deg/RIU at 1200 nm wavelength and simulated FOM values were also found enhanced from 23.3544 RIU− 1 at 632.8 nm to 62.6285 RIU− 1 at 1200 nm wavelength for change in sensing layer refractive indices from 1.30 RIU to 1.35 RIU.