Temperature Spectra Research Articles

Exploration of failure mechanisms in a novel basalt fiber-reinforced phthalonitrile composite under extreme temperature conditions

As composites become increasingly prevalent in aerospace structures, their resistance to high temperatures in extreme environments has captured the attention of numerous scholars. This paper discussed the development of a new basalt fiber-reinforced phthalonitrile matrix (BFRPN) composite, examining its mechanical performance across a spectrum of temperatures, including -55 °C low-temperature dry state (CTD), 23 °C room-temperature dry state (RTD), 250 °C, 350 °C, and 450 °C. The reliability of the mechanical properties was assessed by calculating the B-basis value. Additionally, optical and scanning electron microscope (SEM) photos were employed to analyze the damage morphology and elucidate the failure mechanisms at both high and low temperatures. The study revealed that the BFRPN composites maintained functional integrity from -55 °C to 350 °C. For representative unnotched plate tensile (UPT) and unnotched plate compression (UPC) specimens, the retention of UPT strength and UPC strength stayed above 100% and 83% respectively. At 450 °C, the retention rate of UPT strength consistently exceeds 78%, while the matrix undergoes significant oxidative decomposition, with delamination being the main observed damage mode.

Cyclic functional degradation of NiTi shape memory alloy wires in wide ranges of strain rate and ambient temperature

Shape memory alloy (SMA) dampers frequently experience cyclic loading over a broad spectrum of strain rates and ambient temperatures, resulting in a significant thermo-mechanical coupling effect during cyclic deformation. Nevertheless, the impact of this coupling effect on the functional degradation of SMAs has not been thoroughly examined, particularly in scenarios involving severe deformation. In this study, a series of strain-controlled cyclic loading–unloading tests were conducted on NiTi SMA wires utilizing various combinations of strain rates ranging from 5 × 10−4 6 × 10−2/s and different ambient temperatures (313–393 K). The functional degradation was exacerbated by increasing ambient temperature and loading rate due to the complex interactions among the inelastic deformation mechanisms and thermo-mechanical coupling effects. Furthermore, although the cyclic deformation behavior of NiTi SMA wires varied with the loading rate, this rate dependence diminished with increasing ambient temperature. The synergistic effect of elevated strain rates and high temperatures markedly accelerated the fatigue failure of NiTi SMA wires and substantially altered the underlying microstructural morphology. These findings can provide valuable support for evaluating the service performance of NiTi SMA dampers under various engineering conditions and contribute to developing a cyclic constitutive model for NiTi SMAs.

High-quality InAs homoepitaxial layers grown by molecular beam epitaxy

The growth conditions for InAs homoepitaxy by molecular beam epitaxy were comprehensively studied across a broad spectrum of substrate temperatures, As2/In flux ratios, and growth rates. It was found that the surface morphology and overall quality of the InAs layers were significantly influenced by these parameters. Optimal conditions, including a lower growth temperature, reduced As2 flux, and slower growth rate, were pivotal in achieving high-quality InAs layers. Two primary characterization techniques, differential interference contrast microscopy and atomic force microscopy, were employed to evaluate the material quality. High-quality InAs homoepitaxial layers were successfully grown at a substrate temperature of 455 °C and a growth rate of 0.33 monolayers per second (ML/s). These layers exhibited a remarkably low defect density of approximately 300 defects per square centimeter, which is over an order of magnitude lower than previously reported, and a notably low root-mean-square roughness of 0.116 nm. At a growth rate of 0.33 ML/s, the growth temperature range for InAs homoepitaxial layers was found to be quite broad, whereas the As2/In flux ratio remained within a narrow range. This study underscores the critical role of precise control over growth parameters in the molecular beam epitaxy process for producing high-quality InAs homoepitaxial layers.

Updates to NOAA’s Unified Forecast System’s Cumulus Convection Parameterization Scheme between GFSv16 and GFSv17

Abstract This study outlines the updates made to cumulus convection parameterizations between Global Forecast System, version 16 (GFSv16), and the forthcoming GFSv17 which will be the first global forecast application to become operational under the Unified Forecast System infrastructure. The updates, addressing known systematic errors and biases, incorporate innovations such as stochasticity, three-dimensional subgrid organizational effects, and a prognostic closure evolution. The changes are shown to improve tropical temperature/humidity biases, convective available potential energy (CAPE) forecasts, CONUS precipitation, and tropical variability. By examining individual updates’ impact on temperature, humidity profiles, and precipitation power spectra, we find that the new prognostic closure and stricter precipitation evaporation criteria alleviate a dry and cold bias in the tropical boundary layer and enhance precipitation variability in the tropics. Stricter triggering criteria also allow for more CAPE buildup, particularly over the tropics. The cumulus convection updates have a modest impact on precipitation skill scores over CONUS, but overall, there is an improvement when comparing GFSv16 and the latest GFSv17 prototype configurations, in particularly for larger thresholds. The study also highlights the challenges in developing convection parameterizations suitable for both coupled and uncoupled model configurations. Evaluation of the MJO shows varying responses to cumulus convection changes depending on whether the model is coupled with a dynamic ocean model.

Experimental investigation on temperature distribution characteristics inside the condensing tube of the R134a two-phase natural circulation loop

Temperature distribution of two-phase flow inside the condensing tube can effectively reflect the heat transfer characteristic of the fluid, playing a pivotal role in the study of heat transfer in two-phase flow systems. In this study, we use the stainless steel capillary sealed distributed fiber Bragg grating (S-DFBGs) to measure and characterize the temperature distribution of R134a fluid inside the condensing tube under steady-state (pump-driven two-phase circulation) and unsteady-state (type I and II density wave instabilities in two-phase natural circulation loop) conditions, and the frequency and time domain characteristics of the fluid temperature distribution inside the tube has been investigated in detail. Through frequency-domain analysis, the temperature spectrum inside the condensing tube can indentify two types of the instability together with flowrate and pressure. Through time-domain analysis, temperature distribution inside the condenser can dermine the phase transition point, hence the condensation length. Moreover, two types of the instability exhibit different temperature fluctuation characteristics, providing reliable and effective information for further research on two phase natural circulation instability mechanisms.

Reconfigurable, zero-energy, and wide-temperature loss-assisted thermal nonreciprocal metamaterials

Thermal nonreciprocity plays a vital role in chip heat dissipation, energy-saving design, and high-temperature hyperthermia, typically realized through the use of advanced metamaterials with nonlinear, advective, spatiotemporal, or gradient properties. However, challenges such as fixed structural designs with limited adjustability, high energy consumption, and a narrow operational temperature range remain prevalent. Here, a systematic framework is introduced to achieve reconfigurable, zero-energy, and wide-temperature thermal nonreciprocity by transforming wasteful heat loss into a valuable regulatory tool. Vertical slabs composed of natural bulk materials enable asymmetric heat loss through natural convection, disrupting the inversion symmetry of thermal conduction. The reconfigurability of this system stems from the ability to modify heat loss by adjusting thermal conductivity, size, placement, and quantity of the slabs. Moreover, this structure allows for precise control of zero-energy thermal nonreciprocity across a broad temperature spectrum, utilizing solely environmental temperature gradients without additional energy consumption. This research presents a different approach to achieving nonreciprocity, broadening the potential for nonreciprocal devices such as thermal diodes and topological edge states, and inspiring further exploration of nonreciprocity in other loss-based systems.

Neutrinos from pre-supernova: effects of nuclear temperature onluminosities and spectra

Neutrinos from pre-supernova: effects of nuclear temperature onluminosities and spectra

Effects of changes in temperature and precipitation as climate factors that influence the spread of climate-related diseases: a systematic review

ABSTRACT Climate change is an environmental problem that leads to extreme flood and drought events in various geographical regions. The review seeks to establish pertinent issues around changes in temperature and precipitation as climate factors which have been under-researched. It will be established whether the spread of disease and other human risks have been reported under various temperature and precipitation levels; whether sound adaptation measures are in place; communities are provided with awareness toward adaptation methods; and educated on how to deal with mental problems and anxiety caused by climate change. The review has established that little research has modeled variation in human characteristics like age group differences and health fluctuations with climate change, under a wide spectrum of temperature and precipitation. Southern African countries’ research also lacks projection of climate change impacts and risk distribution maps for vector borne diseases under RCP2.6, RCP4.4, RCP6.0 and RCP8.0. In addition, there has been bias in previous studies regarding a combination of temperature and precipitation, as well as non-climatic factors that may be favorable for spread and transmission of specified VBDs. Recommendations from this review could be adopted by countries in order to protect communities’ health.

Revisiting the A L Lensing Anomaly in Planck 2018 Temperature Data

We revisit the lensing anomaly in the Planck 2018 temperature (TT) data and examine its robustness to frequency selection and additional sky masking. Our main findings are as follows. (1) The phenomenological lensing amplitude parameter, A L , varies with ecliptic latitude, with a 2.9σ preference for A L > 1 near the ecliptic and 1.0σ preference near the ecliptic poles, compared to 2.5σ on the original masks. This behavior is largely or solely from 217 GHz and suggestive of some nonrandom effect, given the Planck scan strategy. (2) The 217 GHz TT data also show a stronger preference for A L > 1 than the lower frequencies. The shifts in A L from 217 GHz with additional Galactic dust masking are too large to be explained solely by statistical fluctuations, indicating some connection with the foreground treatment. Overall, the Planck A L anomaly does not have a single simple cause. Removing the 217 GHz TT data leaves a 1.8σ preference for A L > 1. The low-multipole (ℓ < 30) TT data contribute to the preference for A L > 1 through correlations with ΛCDM parameters. The 100 and 143 GHz data at ℓ ≥ 30 prefer A L > 1 at 1.3σ, and this appears robust to the masking tests we performed. The lensing anomaly may impact fits to alternative cosmological models. Marginalizing over A L , optionally applied only to Planck TT spectra, can check this. Models proposed to address cosmological tensions should be robust to removal of the Planck 217 GHz TT data.

Multi-temperature capable enhanced bidirectional long short term memory-multilayer perceptron hybrid model for lithium-ion battery SOC estimation

In this study, we propose a novel hybrid modeling framework for State of Charge (SOC) estimation across a broad temperature spectrum. First, we build a hybrid model to optimize stacked layers of stacked bidirectional long short term memory networks by introducing dropout mechanisms. At the same time, we also optimize the traditional multi-layer perceptron model to ResMLP, which is improved by introducing residual linkage, and then integrate the two optimization models. Finally, the synergistic effect and attention mechanism of genetic algorithm and particle swarm optimization are used to optimize its parameters. We then rigorously tested the model on nine datasets, including HPPC, DST and BBDST, at different temperatures of 5 °C, 15 °C and 35 °C. Using MAE, RMSE and MAXE benchmarks, our research results show that the proposed hybrid model outperforms the benchmark algorithm, achieving significantly enhanced performance and higher accuracy, and the maximum SOC estimation error is kept below 4.53 %. In addition, experimental evaluation at different temperatures shows the robustness and adaptability of the proposed algorithm.

Molecular interactions in ethyl caprate and 2-alcohol: Extended hard sphere framework

BackgroundThe study investigates the liquid densities and viscosities of Ethyl caprate (EC) combined with various 2-alkanols across a temperature spectrum of 293.15 to 323.15 K, aiming to understand the intermolecular interactions and deviations from ideal behavior. MethodsExperimental density and viscosity for the mixtures were measured with the SVM Stabinger viscometer. A modified rough hard-sphere theory was employed to model the viscosity of pure substances and binary liquids, incorporating temperature-dependent parameters. Significant Findings: All examined mixtures exhibited positive excess molar volumes. The modified rough hard-sphere model demonstrated a maximum viscosity error of 4.12 % for 2-hexanol in the temperature range of 293 to 323 K. For binary mixtures, the calculated values closely matched experimental data, with a maximum deviation of 3.51 % observed for the EC + 2-butanol mixture, highlighting the model's predictive accuracy.

Genome-guided bioprospecting for industrially important enzymes from a thermophilic Bacillus subtilis strain SR-7, an isolate from hot spring of Madhya Pradesh, India

The study focused on isolating thermophilic bacteria from the hot springs of Madhya Pradesh, India, with the aim of identifying strains capable of producing industrially valuable enzymes. Among the 15 isolated strains, SR-7 identified as Bacillus subtilis exhibited significant enzyme activity, leading to its selection for further investigation. Genomic analysis revealed key characteristics of SR-7, including a 3,593,163 base pair chromosome with a GC content of 44.14 %. The genome was found to contain 55 tRNA genes, four rRNA clusters, and 3744 protein-coding genes. These genes encompass essential metabolic pathways and genes responsible for thermophilic adaptation, highlighting the potential for industrial applications. Further experimentation demonstrated SR-7 have the ability to produce various enzymes of industrial significance, such as amylase, lipase, cellulase, protease, lecithinase, gelatinase, and pectinase. Importantly, enzyme production was observed across a broad pH range (6.5 to 10) and temperature spectrum, indicating the versatility and adaptability of SR-7 to different environmental conditions. The findings suggest that SR-7 holds promise as a valuable resource for the pharmaceutical and industrial sectors. Its capacity to produce thermostable enzymes suitable for a range of applications underscores its potential contribution to biotechnological processes. By harnessing the enzymatic capabilities of thermophilic bacteria like SR-7, industries can pursue more sustainable and efficient production methods, reducing reliance on traditional chemical processes and enhancing overall productivity. Further research into the enzymatic properties and genetic mechanisms of SR-7 may unveil additional avenues for its utilization in various industrial processes.

Low temperature phase transitions in the visible and near-infrared (VNIR) reflectance spectra of (NH4)2HPO4 and (NH4)HSO4 salts

The detection of ammonium bearing crystalline solids in salt-water systems on icy bodies and solar system bodies could provide information about the ascent of these salts from a deep reservoir within the hydrosphere. Due to their chemical-physical properties, NH4+ compounds play a key role both in the internal dynamics of celestial bodies and in the potential habitability of ocean worlds. In this work we analysed the reflectance spectra of two synthetic NH4+ salts: ammonium hydrogen phosphate (NH4)2HPO4 and ammonium hydrogen sulphate (NH4)HSO4 in the 1–4.2 μm spectral range at low temperature, between 110 and 290 K. For (NH4)2HPO4 we also examined the effect of three different grain sizes (150–125 μm; 125–80 μm; 80–32 μm). The collected reflectance spectra show absorption features related to NH4+ group overtone and combination modes in the 1–2.5 μm range. In particular, the bands located at ∼1.09 μm (3ν3), ∼1.30 μm (2ν3 + ν4), ∼1.58 μm (2ν3), ∼2.02 μm (ν2 + v3) and ∼ 2.2 μm (v3 + v4) could be useful to discriminate these salts. The low temperature spectra, compared to those at ambient temperature, reveal finer structures, displaying sharper and narrower absorption bands. The selected NH4+-bearing salts are subjected to reversible low temperature phase transitions, which are revealed in the spectra by a progressive growth and shift of the bands toward shorter wavelengths with a drastic change of their depth. We performed laboratory measurements of ammonium (NH4+) compounds to address the limited data available expanding the existing database. The collected cryogenic spectra can be directly compared with remote sensing data from planetary missions of the upcoming decade such as NASA's Europa Clipper, and ESA's JUICE and the newly launched James Webb Space Telescope expanding the existing database of ammonium compounds at cryogenic temperature.

Dielectric relaxation and electrical conductivity in lead-free organic ferroelectric diisopropylammonium bromide (dipaBr)

In this communication, we explore the dielectric relaxation behavior of the novel organic salt Diisopropylammonium Bromide (dipaBr), focusing on the universal relaxation law. We conduct dielectric relaxation and conductivity analyses across a broad spectrum of temperatures (325K–443K) and frequencies (20 Hz–20 MHz). The irregularity in peak broadening observed in complex modulus spectroscopy indicates a distribution of relaxation periods with varying time constants, confirming that the relaxation is of the non-Debye type. To interpret the experimental findings, we utilize the Havriliak-Negami (HN) formula in our investigation of dielectric relaxation. The parameters derived from the model are discussed. The relaxation process in the material appears to depend on temperature. The ac conductivity profile follows Jonscher's universal power law, and the relationship between bulk DC conductivity and temperature follows an Arrhenius-like pattern.

The ethylene absorption spectrum between 6075 and 8050 cm-1: Empirical line list and rovibrational assignments

The highly congested absorption spectrum of ethylene (C2H4) is analyzed between 6075 and 8050 cm-1. In the 6200–8050 cm-1 range, a list of about 32,650 lines is retrieved from a room temperature spectrum recorded by Fourier transform spectroscopy (P = 15.72 mbar, L = 45 m). This dataset was merged with a set of about 3460 lines available in the literature in the region of the strong ν5+ν9 band near 6150 cm-1. In addition, two FTS spectra at 130 K provide complementary information in the 6020–6320 cm-1 range (about 7570 lines).Relying on the position and intensity agreements with a line list of 12C2H4 transitions calculated by the variational method, a total of 4090 transitions is assigned to eighteen bands, ten of them being newly reported. All the reported assignments are confirmed by Lower State Combination Difference (LSCD) relations i.e. all the upper states (1749 in total) have coinciding determinations of their energies through several transitions (up to 6). The obtained empirical energy values are given and compared to their variational counterpart. As an additional validation test of the lower state assignments, the room temperature intensities are extrapolated at 130 K and compared to their experimental values. Overall, a large fraction of the strong lines of the region is assigned and the total intensity of the assigned transitions represents 46 and 55% of the total variational and experimental intensities at 296 K, respectively. In the considered range, variational positions deviate from measurements by a few cm-1 and the total variational absorption is underestimated by 40 %.

The association of outdoor temperature and self-reported Raynaud's phenomenon severity among people with systemic sclerosis: a Scleroderma Patient-centered Intervention Network Cohort study

Raynaud's phenomenon is the earliest and most common systemic sclerosis manifestation. Episodes can be triggered by cold exposure and ambient temperature changes. Small studies have found that Raynaud's phenomenon outcomes were associated with season. We aimed to map the degree that differences in ambient temperature are associated with Raynaud's phenomenon outcomes across the temperature spectrum. People with Raynaud's phenomenon secondary to systemic sclerosis in the Scleroderma Patient-centered Intervention Network Cohort completed past-week Raynaud's phenomenon severity assessments (0-10 numerical rating scale) at enrolment and longitudinally at 3-month intervals. Mean daily temperature and feels like temperature, which incorporates wind chill and humidity, for the week before each assessment were extracted for each participant from a weather site close to the participant's recruiting centre via the Iowa Environmental Mesonet. We used linear mixed models with basis splines to flexibly model non-linear changes in Raynaud's phenomenon severity across the temperature spectrum. People with lived experience of systemic sclerosis contributed to the study design and interpretation. Between April 15, 2014 and Aug 1, 2023, we included data on 20 233 Raynaud's phenomenon severity assessments from 2243 participants. 1964 (88%) of 2243 participants were women, 279 (12%) were men, and 1813 (82%) were White. Mean age was 54·8 (SD 12·7) years. The maximum predicted Raynaud's phenomenon severity score was 6·8 points (95% CI 5·6-8·1), which occurred at -25°C. Severity scores decreased minimally from -15°C to 5°C (0·05-0·21 points per 5°C difference), then decreased in larger steps between 5°C and 25°C (0·37-0·54 points per 5°C difference). The minimum predicted score was at 25°C (2·6 points [95% CI 2·5-2·7]). Scores increased at temperatures above 25°C to 3·5 points (3·0-4·1) at 35°C and 5·6 points (4·5-6·8) at 40°C. Results were similar for feels like temperature. Raynaud's phenomenon severity is worst at very cold temperatures but also increases with very warm temperatures, presumably due to air conditioning. Clinical management and Raynaud's phenomenon intervention trial designs should consider temperature patterns. Scleroderma Society of Ontario, Scleroderma Canada, Sclérodermie Québec, Scleroderma Manitoba, Scleroderma Atlantic, Scleroderma Association of BC, Scleroderma SASK, Scleroderma Australia, Scleroderma New South Wales, Scleroderma Victoria, the Canadian Institutes of Health Research, the Arthritis Society, the Lady Davis Institute for Medical Research of the Jewish General Hospital, the Jewish General Hospital Foundation, and McGill University.

Conceptual Models for Exploring Sea-Surface Temperature Variability Vis-à Long-Range Weather Forecasting

This paper analyzes the ability of three conceptual stochastic models (one-box, two-box, and diffusion models) to reproduce essential features of sea surface temperature variability on intra-annual time scales. The variability of sea surface temperature, which is particularly influenced by feedback mechanisms in ocean surface–atmosphere coupling processes, is characterized by power spectral density, commonly used to analyze the response of dynamical systems to random forcing. The models are aimed at studying local effects of ocean–atmosphere interactions. Comparing observed and theoretical power spectra shows that in dynamically inactive ocean regions (e.g., north-eastern part of the Pacific Ocean), sea surface temperature variability can be described by linear stochastic models such as one-box and two-box models. In regions of the world ocean (e.g., north-western Pacific Ocean, subtropics of the North Atlantic, the Southern Ocean), in which the observed sea surface temperature spectra on the intra-annual time scales do not obey the ν−2 law (where ν is a regular frequency), the formation mechanisms of sea surface anomalies are mainly determined by ocean circulation rather than by local ocean–atmosphere interactions. The diffusion model can be used for simulating sea surface temperature anomalies in such areas of the global ocean. The models examined are not able to reproduce the variability of sea surface temperature over the entire frequency range for two primary reasons; first, because the object of study, the ocean surface mixed layer, changes during the year, and second, due to the difference in the physics of processes involved at different time scales.

Highly conductive and stable double network carrageenan organohydrogels for advanced strain sensing and signal recognition arrays

Conductive hydrogels with excellent mechanical properties, a broad detection range, and stability in complex environments have remained a significant challenge for the development of flexible sensors. In this study, a straightforward freeze-thaw cycles strategy was developed to fabricate a polyvinyl alcohol (PVA)/carrageenan (CA)/calcium chloride (CaCl2)/MXene-based double network organohydrogel (PCCME) for highly flexible and responsive strain detection across a broad temperature spectrum. The PCCME organohydrogel features multiple interactive forces including hydrogen bonding, ionic interactions, and microphase crystallization, which contribute to the organohydrogel's exceptional mechanical and electrical performance. The PCCME organohydrogel exhibited excellent performance in a load-unload test repeated 100 times after being maintained at room temperature for 7 days, with a minimal mechanical decay of only 2.6%. Furthermore, the repaired PCCME organohydrogel retained its robust stability after storage at low temperatures followed by placement at room temperature. The organohydrogel sensor not only detects various movement amplitudes of the human body but also recognizes arrays of pressure signals and converts these into digital images, highlighting its significant potential for applications in rehabilitation monitoring, pressure sensing, and human-computer interaction.

The Impact of Gamma Irradiation on 4H-SiC Bipolar Junction Inverters under Various Biasing Conditions

In this study, we introduce the impact of gamma irradiation on 4H-SiC based transistor-transistor logic (TTL) inverters. These monolithic bipolar inverters have been successfully demonstrated in a broad spectrum of temperature and supply voltage conditions. In this iteration of experiments, attempts made to the processing to increase beta values. The gamma radiation tests from a 60Co source were conducted under various operation conditions and measured in-situ under different biasing conditions. The Silicon Carbide Integrated circuits ( SiC ICs) show excellent tolerance properties to gamma radiation up to doses of nearly 1 MRad. Comparable Si BJT-based TTL inverters show considerable degradation already at one order of magnitude lower doses, clearly demonstrating the superior radiation hardness of 4H-SiC ICs.

Fracture Analysis of Highly Flexible Adhesives: Cohesive Zone Modelling across a Wide Spectrum of Temperatures and Strain Rates.

This study focuses on the prediction of the fracture mechanics behaviour of a highly flexible adhesive (with a tensile elongation of 90%), since this type of adhesive is becoming widely used in automotive structures due to their high elongation at break and damping capacity. Despite their extensive applications, the understanding of their fracture mechanics behaviour under varying loading rates and temperatures remains limited in the literature. In addition, current prediction models are also unable to accurately predict their behaviour due to the complex failure mechanism that such bonded joints have. This study aims to determine whether a simple triangular cohesive zone model (CZM), which predefines the crack path, can reproduce the load-displacement curves of adhesives under various temperatures and strain rates. To achieve this, a calibrated CZM is used, adapting the model for reference joints and then validating it with independent test results conducted in a wide range of loading and environmental conditions. The tests were performed at speeds between 0.2 and 6000 mm/min and at three different temperatures ranging from -30 °C to 60 °C. Mode I fracture toughness was measured using the DCB (double cantilever beam) specimens. Using a simple triangular CZM may not be optimal for predicting the mechanical response of highly flexible adhesives with complex failure mechanisms and multiple crack paths. However, by correctly adjusting the cohesive zone properties for a limited set of reference conditions, it is possible to accurately predict the mechanical response of these joints across various test speeds and temperatures, significantly reducing costs and effort.