Temperature-dependent Correction Research Articles

A Temperature-Transferable Coarse-Grained Model for Poly(lactic Acid) Melts.

We present a temperature-transferable coarse-grained (CG) model for poly(lactic acid) (PLA), specifically designed to replicate its volumetric properties and solubility parameter in the molten state. The CG-bonded potentials were derived by using the iterative Boltzmann inversion (IBI) optimization method to match structural properties from detailed atomistic models. A parametrization workflow was employed to determine nonbonded interaction parameters with temperature-dependent corrections that provide agreement with the target properties across the melting temperature range. The CG model successfully replicates key features of the PLA melt. It satisfactory reproduces the density and solubility parameter, maintains the dependence of chain conformation on molecular weight, and captures the dynamic behavior through agreement in scaled mean squared displacement and diffusion coefficients with the atomistic model. Additionally, the CG model offers much faster equilibration compared with the atomistic model. The proposed model is expected to be particularly useful for investigating the miscibility characteristics of PLA in various blends and composites that remain challenging to explore using fully atomistic simulations or experiments.

Temperature dependence of constant current hot-film sensors: Investigation with application to temperature correction for wall-shear stress measurements

Hot-film sensors measure wall-shear stress based on the forced convective heat transfer. Variations of ambient temperatures lead to significant measurement errors for such thermal sensors and must be corrected for sometimes. Although methods for correcting the temperature shifts of hot-film sensors driven in constant temperature or constant voltage mode have been suggested over the years, the temperature dependence and relevant correction schemes of constant current mode of operation are still open questions. In this study, temperature dependence characteristics of constant current hot-film sensors are investigated within relatively large temperature changes in air and water channel flows (28 °C and 16 °C, respectively). The specific property of constant overheat ratios under varying temperatures for constant current driving mode is found and a quite simple temperature correction function is derived on that basis to eliminate the temperature dependence without any assumed heat transfer correlation. With the correction function, the data at different ambient temperatures are collapsed to single curves with high R2 factors over 0.99, typically. Furthermore, after correction, the relative errors of the measured wall-shear stress are reduced to within ±6 % of the true values. It will then enable the constant current hot-film sensors to calibrate at only one ambient temperature instead of a multiple range of temperatures as with many other schemes, which is more practical and convenient.

Fast relaxation in metallic glasses studied by measurements of the internal friction at high frequencies

We performed high-frequency (0.4–1.7 MHz) measurements of the internal friction (IF) on 14 bulk metallic glasses (MGs). It is found that 12 of these MGs display relaxation IF peaks at temperatures ≈ 400–500 K, which are weakly affected by heat treatment within the amorphous state. The corresponding relaxation time is about 0.3 μs. This fast relaxation is reported for the first time in the literature. The apparent activation enthalpy for 4 MGs is determined. It is shown that if measured at a low frequency of 1 Hz, these IF peaks would appear near room temperature or by 30–50 K below it. Thus, the IF peaks found in the present investigation are direct analogues of low-temperature/low-frequency β′- and/or γ-relaxations described in the literature. It is argued that the origin of these IF peaks is related to the relaxation of structural defects similar to dumbbell interstitials, which are frozen in solid glass from the liquid state upon melt quenching. These defects can be considered as elastic dipoles and their re-orientation in the applied stress provides anelastic deformation and corresponding IF peak. After correction for temperature dependence of the shear modulus, the true activation enthalpy (0.62–1.08 eV) and activation entropy (4 ≤ΔS∕kB≤15) for defect re-orientation are determined.

Modeling the impact of the temperature profile on the sedimentation process for shear thinning suspensions in the annulus of oil well

The particle settling phenomena were broadly studied in the literature experimentally and numerically. To the best of our knowledge, previous works do not consider the temperature effect on the suspension rheology and, consequently, the influence over the settling velocity. Motivated by the problem of the sedimentation in confined drilling fluids exposed to a geothermal temperature gradient, this work proposed a continuum model for the sedimentation process of weighting agents in non-Newtonian suspensions based on the Mixture Theory. A temperature-dependent correction for the suspension consistency index was proposed and the results were discussed for different temperature profile cases, including uniform temperature profile, linear and geothermal profiles. Numerical simulations were performed, using the Finite Volume technique. Results for the solids concentration along the column for up to five years were discussed as well as the solids concentration evolution for selected points along the column. The results showed that the temperature gradient significantly impacts the settling velocity and the evolution of sedimentation regions. The main affected zones were the free settling and the sediment zones, which can alter directly parameters of interest for applications in oil wells, such as the height of sediment.

Enhancing infrared imaging systems with temperature-dependent nonuniformity correction via single-frame and inter-frame structural similarity.

Temperature-dependent nonuniformity in infrared images significantly impacts image quality, necessitating effective solutions for intensity nonuniformity. Existing variational models primarily rely on gradient prior constraints from single-frame images, resulting in limitations due to insufficient exploitation of intensity characteristics in both single-frame and inter-frame images. This paper introduces what we believe to be a novel variational model for nonuniformity correction (NUC) that leverages single-frame and inter-frame structural similarity (SISB). This approach capitalizes on the structural similarities between the corrected image, intensity bias map, and degraded image, facilitating efficient suppression of intensity nonuniformity in real-world scenarios. The proposed method diverges fundamentally from existing strategies and demonstrates superior performance in comparison with state-of-the-art correction models.

On the origin of the negative energy-related contribution to the elastic modulus of rubber-like gels.

We consider a coarse-grained polymer model in order to investigate the origin of a recently discovered negative energy-related contribution to the elastic modulus G(T) of rubber-like gels. From this model, we are able to compute an exact expression for the free energy of the system, which allows us to evaluate a stress-strain relationship that displays a non-trivial dependence on the temperature T. We validate our approach through comparisons between the theoretical results and the experimental data obtained for tetra-PEG hydrogels, which indicate that, although simple, the present model works well to describe the experiments. Importantly, our approach unveiled aspects of the experimental analysis which turned out to be different from the conventional entropic and energetic analysis broadly used in the literature. Also, in contrast to the linear dependence predicted by the traditional, i.e., purely entropic, models, our results suggest that the general expression of the elastic modulus should be of the form [Formula: see text], with w(T) being a temperature-dependent correction factor that could be related to the interaction between the chains in the network and the solvent. Accordingly, the correction factor allows the expression found for the elastic modulus to describe both rubber and rubber-like gels.

Temperature-dependent analysis and correction in a neutron fluence real-time measuring circuit

A real-time measuring circuit for neutron (1 MeV equivalent) fluence measurement is presented in this paper. The discrete bipolar junction transistor (BJT) is used as the neutron fluence monitor, according to the change in the reciprocal of the current gain varying linearly with the neutron fluence. However, a measuring error cannot be neglected due to the temperature dependence of the BJT current gain. By analyzing the temperature parameters of the current gain equation, the analytic relation between current gain and temperature is obtained, and the correction method of the measurement error caused by the change in temperature is represented. The experimental results show that the corrected measurement error decreases obviously in a larger temperature range. As a result, the measurement accuracy is improved evidently.

Temperature-induced magnonic Chern insulator in collinear antiferromagnets

Thermal fluctuation in magnets causes temperature-dependent self-energy corrections in magnons; however, its effects on the topological orders of magnons is not well explored. Here we demonstrate that such corrections can induce a Chern insulating phase in two-dimensional collinear antiferromagnets with sublattice asymmetries by increasing temperature. We present the phase diagram of the system and show that the trivial magnon bands at zero temperature exhibit Chern insulating phase above a critical temperature before the paramagnetic phase transition. The self-energy corrections close and reopen the band gap at $\mathrm{\ensuremath{\Gamma}}$ or $\mathbf{K}$ points, accompanied by a magnon chirality switch and nontrivial Berry curvature transition. The thermal Hall effect of magnons or detecting the magnon polarization can highlight the experimentally prominent signatures of the topological transitions. We include the numerical results based on the van der Waals magnet ${\mathrm{MnPS}}_{3}$, calling for experimental implementation. Our work presents a paradigm for constructing topological phases that is beyond the linear spin wave theory.

Topological transport properties of highly oriented Bi2Te3 thin film deposited by sputtering

Topological insulators (TIs) are the promising materials for next-generation technology due to their exotic features such as spin momentum locking, conducting surface states, etc. However, the high-quality growth of TIs by sputtering technique, which is one of the foremost industrial requirements, is extremely challenging. Also, the demonstration of simple investigation protocols to characterize topological properties of TIs using electron-transport methods is highly desirable. Here, we report the quantitative investigation of non-trivial parameters employing magnetotransport measurements on a prototypical highly textured Bi2Te3 TI thin film prepared by sputtering. Through the systematic analyses of the temperature and magnetic field dependent resistivity, all topological parameters associated with TIs, such as coherency factor , Berry phase (), mass term (m), the dephasing parameter (p), slope of temperature dependent conductivity correction () and the surface state penetration depth (λ) are estimated by using the modified ‘Hikami–Larkin–Nagaoka’, ‘Lu–Shen’ and ‘Altshuler–Aronov’ models. The obtained values of topological parameters are well comparable to those reported on molecular beam epitaxy grown TIs. The epitaxial growth of Bi2Te3 film using sputtering, and investigation of the non-trivial topological states from its electron-transport behavior are important for their fundamental understanding and technological applications.

Experimental and Correction Methods for Responsivity Temperature Dependence in the SWIR Bands of a Spaceborne Scanning Polarimeter

Photodetector spectral responsivity is usually affected by photosensitive surface temperatures. The Photosensitive Surface Temperatures (PSTs) of the long wavelength-type InGaAs detector used in the Polarized Scanning Atmospheric Corrector (PSAC), which adopts an active Constant-Current Cooling (CCC) scheme, can be changed with ambient temperature. To correct this responsivity temperature characteristic, a Responsivity Temperature Dependence Correction (RTDC) model was established with parameters obtained using an instrument-level experiment. Moreover, a detector-level experiment under ambient conditions was also explored to acquire model parameters. The instrument-level and detector-level experimental results show that the responsivity of a PSAC 2250 nm channel operating on orbit (PST ≈ −65 °C) with a 35 °C PST difference is reduced by approximately 1.2% and 1.5% compared with a laboratory-based radiometric test (PST ≈ −30 °C). The 1.08% responsivity change (−61 °C < PST < −38 °C) in the temperature drift simulation experiment is reduced to approximately 0.38% and 0.34%, respectively. The consistency between the two experimental results preliminarily verifies the substitutability of this detector-level experiment for this type of detector. The RTDC experiments are applicable to other spaceborne remote sensors. The detector-level experiment explored herein provides a reference for realizing RTDC under ambient temperature conditions at low costs.

Mid-IR Observations of IRAS, AKARI, WISE/NEOWISE, and Subaru for Large Icy Asteroid (704) Interamnia: A New Perspective of Regolith Properties and Water Ice Fraction

(704) Interamnia is one of the largest asteroids located in the outer main-belt region, which may contain a large amount of water ice underneath its surface. We observe this asteroid using 8.2 m Subaru telescope at mid-infrared wave bands and utilize a thermophysical model for realistic surface layers to analyze mid-infrared data from Subaru along with those of IRAS, AKARI, and Wide-field Infrared Survey Explorer (WISE)/NEOWISE. We optimize the method to convert the WISE magnitude to thermal infrared flux with temperature-dependent color corrections, which can provide significant references for main-belt asteroids at a large heliocentric distance with low surface temperature. We derive best-fitting thermal parameters of Interamnia—a mean regolith grain size of μm, with a roughness of and rms slope of deg, thereby producing thermal inertia ranging from 9 to 92 Jm−2 s−1/2 K−1 due to seasonal temperature variation. The geometric albedo and effective diameter are evaluated to be and , respectively, being indicative of a bulk density of 1.86 ± 0.63 g cm−3. The low thermal inertia is consistent with typical B/C-type asteroids with D ≥ 100 km. The tiny regolith grain size suggests the presence of a fine regolith on the surface of Interamnia. Moreover, the seasonal and diurnal temperature distribution indicates that thermal features between the southern and northern hemispheres appear to be very different. Finally, we present an estimation of volume fraction of water ice of 9%–66% from the published grain density and porosity of carbonaceous chondrites.

Temperature dependent performance of Schmidt-Boelter heat flux sensors.

The total heat flux sensors for NASA's Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2) sensor suite on the Mars 2020 vehicle and the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) technology demonstration mission are passively cooled Schmidt-Boelter gauges. The output of these sensors has been experimentally demonstrated to be dependent on the temperature of the sensing element. The experimental results are shown to align with a model that assumes temperature-dependent material properties, specifically the Seebeck coefficient. The MEDLI2 and LOFTID flight total heat flux sensors did not undergo a full thermal calibration prior to being installed on the flight vehicles since the temperature dependence was unknown ahead of time. Additionally, the material properties are not known due to the designs being proprietary. For these reasons, an approximate correction factor was derived. The applicability and associated uncertainty of this temperature-dependent correction factor are presented. The error that would be introduced into the measurement if temperature effects were not accounted for would be as high as 9.5% and 16% for the MEDLI2 and LOFTID total heat flux sensors, respectively. As a best practice for future flight missions and ground-based applications that employ similar passively cooled heat flux sensors, it is recommended to individually calibrate each sensor across all applicable use temperatures to account for sensor-to-sensor variations and minimize measurement uncertainty.

Temperature Dependent Band Gap Correction Model Using Tight-Binding Approach for UTB Device Simulations

In order to accurately determine the electrostatics of Ultra-Thin-Body (UTB) devices, the semi-empirical tight-binding (TB) approach is widely used for calculating the channel thickness dependent band structure of any material at those temperatures where TB parameters are available (generally defined at 0 K and 300 K). In this work, we analyze the variation of band structure for Si, Ge, and GaAs over different channel thicknesses at 0 K and 300 K, and show that the band curvature at the band minima remains unchanged with temperature, while the band gap changes significantly and affects the channel electrostatics. Based on this finding, we propose an approach to simulate the electrostatics of UTB devices, at any temperature between 0 K and 300 K, using the band structure obtained at 0 K, along with a suitable channel thickness and temperature-dependent band gap correction. From the results obtained for the channel charge density, we show good agreement with band structure based simulation results, at 300 K, over a wide range of channel thicknesses, for Si, Ge, and GaAs, while also showing good agreement with TCAD simulation results, at a typical intermediate temperature of 150 K, thus highlighting the accuracy, simplicity and wide applicability of the proposed approach.

Thermomechanical vibration and stability of effectively homogenized FGM beam with temperature-dependent shear correction factors

Thermomechanical characteristics in the Functionally Graded Materials (FGMs) have been investigated in depth for the precise modeling and analysis of structures in ultimate thermal environments. On this subject, the micro-mechanical interactions of particles in the mixtures of FGMs is necessary to consider the more accurate estimation of structural model. Therefore, the effective material properties are obtained by using homogenization technique based on Mori-Tanaka scheme (MTS) with temperature-dependent material properties. In this regard, present research studies detail temperature-dependent frequencies and thermal buckling behavior of beam model. Then, the physical neutral surface concept is adopted to formulate the decoupled set of stress–strain relations for the FGM models. Also, the First-order Shear Deformation Theory of Beam with rectangular cross-sectional shape including temperature-dependent shear correction factors is developed to improve the practical applications. Furthermore, the results compared with previous data, and the present model is studied in the broad range of temperatures. Specifically, the correlations of shear correction factors and neutral surface shifts are discussed for the models according to temperature and volume fractions. Finally, the thermal stability and the natural frequencies of vibration behaviors are discussed as a result of the mixture ratio for the materials. Furthermore, the mutual interactions of micro-mechanical behavior with the correction factors are especially investigated for thermomechanical analysis.

Temperature-dependent shear correction factor with heat transfer based on micromechanical properties for FGM plates

For a development of aerospace structures in high-temperature regions, Functionally Graded Materials (FGMs) have been used rather than conventional composites. In this regard, present work considers the FGM models in thermal environments, and crucial evaluation to supplement the heat conduction is investigated. To model the thermal–structural interactions, the First-order Shear Deformation Theory is adopted with temperature-dependent characteristics including thermo-micromechanical properties. And the material distributions through the thickness direction are then examined in two types such as the Power- and the Sigmoid-laws. Furthermore, the Mori–Tanaka method for homogenization technique is employed for the precise micromechanical interactions of the mixture particles. Moreover, the un-symmetry of material properties in the structure is considered with physical neutral surface concept. To ensure the validity of this study, the previous literatures are used to compare with the present numerical results. And then, shear correction factors are fully discussed using homogenization methods and the temperature-dependent material properties for micromechanical modeling. Additionally, the effect of heat conduction is studied in detail according to the Poisson’s ratio and Young’s modulus of the mixtures.

The geometrical and temperature-dependent local field correction effects on the effective mass renormalization in a 2DEG

The paper aims at providing new theoretical insights into geometrical and local field correction effects on the effective mass renormalization of interacting electrons in a two-dimensional electron gas, at finite temperature. For this purpose, the temperature-dependent dynamic dielectric function is studied within random phase approximation. Then, the short-range effects of exchange-correlation holes around electrons are employed in calculations through local field correction using Hubbard, finite-temperature Hubbard, and Singwi-Tosi-Land-Sjolander approximations. Finally, the effective mass renormalization is calculated utilizing the real part of the electron self-energy. The outcomes indicate that the effective mass renormalization is decreased with increasing of the thickness at all dimensionless electron densities within all approximations. Likewise, utilizing a local field correction will lead to reductions in effective mass renormalization at any temperature and dimensionless electron density.

Thermal corrections for positronium

Temperature-dependent corrections to energy levels, including relativistic effects, for the positronium atom are discussed. The theoretical description of the thermal environment impact on atomic characteristics is carried out within the framework of rigorous relativistic quantum electrodynamics. As a result, the finite temperature corrections to the fine and hyperfine structure of positronium levels are evaluated. In addition, the annihilation rates of a positronium atom placed in an equilibrium thermal environment (blackbody radiation field) are studied. The numerical results are discussed throughout the paper in view of modern experiments.

Pairing Fluctuation Corrections to the Kinetic Theory of Liquid $$^3\mathrm {He}$$

Liquid $$^3\mathrm {He}$$ is a Fermi liquid that undergoes a BCS-type phase transition to a spin-triplet superfluid, making it valuable for understanding interacting fermions. When the temperature approaches the transition temperature $$T_{\mathrm {c}}$$ from above, physical properties can be modified by Cooper pair fluctuations, leading to deviations from the predictions of Fermi liquid theory. We use nonequilibrium Green’s function theory to study the role of pair fluctuations on quasiparticle transport. The Boltzmann–Landau kinetic equation, which describes the transport properties of Fermi liquids, acquires corrections from the interaction of quasiparticles with pair fluctuations. As an application, we study the effects of pair fluctuations on the propagation of zero sound in liquid $$^3\mathrm {He}$$ . We calculate the temperature-dependent correction to the zero sound velocity due to pair fluctuations and compare the result with existing experimental data.

Improved natural convection heat transfer correlations for reactor cavity cooling systems of high-temperature gas-cooled reactors: From computational fluid dynamics to Pronghorn

The reactor cavity cooling system (RCCS) is a common reactor safety system in high-temperature gas-cooled Reactors (HTGR) that removes heat from the reactor pressure vessel (RPV) by radiation (∼80%) and natural convection (∼20%). For the simulation of accident scenarios of HTGRs, intermediate fidelity and system codes models must be employed to limit the models’ execution time. While an accurate quantification of the radiative heat transfer is available in these models, the quantification of natural convection must rely on correlations of questionable accuracy for the Nusselt number. Commonly used correlations are based in experiments performed at low Rayleigh numbers and/or using isothermal walls in simplified geometries. This work improves on the accuracy of natural convection heat transfer correlations to support HTGR designs.These correlations include both local and average Nusselt numbers as a function of the global Rayleigh number, the local Rayleigh number, and the temperature profile at the hot wall of the RCCS. In the absence of dedicated experiments and the difficulty of performing high-fidelity simulations at realistic Rayleigh numbers, the data to fit the correlations are generated with computational fluid dynamics (CFD) using Reynolds Averaged Navier-Stokes (RANS) models. First, a careful selection of the RANS turbulence model is performed by comparing the results obtained with different RANS turbulence models against high-fidelity simulations of natural convection at Ra 1×1011 in a rectangular cavity. Next, the selected model is used to perform simulations of an HTGR cavity at different high Rayleigh numbers ∈[6.1×1011,2.9×1013] to encompass several HTGR designs, assuming an isothermal RPV wall. The results obtained are used to fit a correlation for the average and space-varying Nusselt number as a function of the global and local Rayleigh numbers via a sparsity-promoting, least-squares method. The selected RANS model is then used to perform simulations of a PBMR-400 (Pebble Bed Modular Reactor) HTGR cavity with the temperature profiles at the RPV wall obtained during a PLOFC (Pressurized loss of forced cooling) transient. We use the results obtained to fit a temperature-dependent correction to the space-varying Nusselt number with the sparsity-promoting, least-squares method. The results obtained in this work enable system-level codes, such as Pronghorn, to perform higher-fidelity simulations of the heat exchange process in the RCCS while still maintaining a low computational cost.

Temperature dependence correction method of LED filament lamp for total luminous flux calibration based on voltage measurement

Light-emitting diode (LED) standard lamps are interesting since the traditional incandescent standard lamps for photometry are difficult to obtain. Many of the National Metrology Institutes have started projects to study the use of LED standards for photometric comparison. The National Institute of Metrology, China, has developed a type of LED filament lamp for total luminous flux. The lamp mimics the 4π incandescent standard lamp and has no space for an active temperature control component. A temperature dependence correction method is reported using the coefficient of the lamp voltage to the output luminous flux. The luminous flux correction is derived from the lamp voltage value. By applying correction, the stability test of the LED filament lamp shows that the ageing effect was estimated to be less than 0.1%/210 days. The temperature dependence was suppressed to less than 0.1% for a range of 21 °C ± 2 °C, which could be due to possible temperature fluctuations of the lamp ambient temperature during measurement by the goniophotometer or integrating sphere.