Effect Of Temperature Variation Research Articles

Superelastic behavior of novel Ni-Ti-Co shape memory alloys for seismic applications

Abstract Ni-Ti-Co is a new shape memory alloy (SMA) that has higher strength and lower superelastic temperature range than traditional binary Ni-Ti SMA. In this paper, the superelastic properties of Ni-Ti-Co bars that are important for seismic applications were studied and compared with those of Ni-Ti bars. The superelastic behavior, strength, strain recovery, low-cycle fatigue characteristics, and fracture strains of Ni-Ti-Co and Ni-Ti SMA with different heat treatment strategies and testing temperatures from -40℃ to 50℃ were investigated with seismic applications in mind. The effect of low-cycle fatigue loading and temperature variation on the superelasticity degradation of Ni-Ti-Co SMA were evaluated. The results showed that the yield strength of Ni-Ti-Co SMA at room temperature was 1.41 ~ 1.74 times that of the Ni-Ti SMA. Ni-Ti-Co SMA exhibited 100% strain recovery when unloaded from 5% strain in a temperature range from -40℃ to room temperature; while at 50℃, a residual strain of 0.6% was observed when unloaded from 5% strain. For comparison, the Ni-Ti SMA lost superelasticity when the temperature was reduced to 0℃. When subjected to low-cycle fatigue loading, the stability of the superelasticity behavior (maintaining yield stress, energy dissipation and strain recovery) of Ni-Ti-Co SMA at -40℃ was better than that at room temperature and 50℃. In particular, the superelasticity of Ni-Ti-Co SMA at -40℃ was even superior to that of the Ni-Ti SMA at 0℃. At -40℃, the Ni-Ti-Co SMA showed no loss in yield stress, damping ratio and recovery strain during the first 100 cycles of fatigue loading. Moreover, from 100th to 471st cycle, at which fracture occurred, the strain recovery of Ni-Ti-Co SMA showed almost no degradation.

Thermomechanobiology as a new research field in soft tissues

During intense galloping, the difference in temperature between the external and the central part of an equine superficial digital flexor tendon can be as high as 7°C. Thirty minutes of jogging modifies the temperature in human knee cartilage from 32°C to 37°C. Intrinsic dissipative phenomena related to the viscoelastic behavior of soft tissues have been identified to be primarily responsible for the observed temperature increase, a situation referred to as self-heating in mechanics. While a 5°C increase may be considered negligible from a mechanical point of view in the cartilage at first sight, it can have a significant biological impact. It has been recently proposed that self-heating and the resulting increase of temperature in cartilage following mechanical stimulation can be necessary for its maintenance. This new concept complements the general acceptance that mechanobiology is central to the homeostasis of musculoskeletal tissues. In most biomechanical and biological studies on cartilage or other soft tissues, the temperature is set at 37°C and considered constant, despite human knee cartilage at rest being around 32°C, for example. Therefore, there is a deficit of information on the role and effect of physiological temperature variation induced through mechanical loading in soft tissues, opening a new research avenue that we coin thermomechanobiology.

A Study of the Effect of Temperature on the Capacitance Characteristics of a Metal-μhemisphere Resonant Gyroscope.

Metal-μhemispherical resonant gyros (M-μHRGs) are widely used in highly dynamic navigation systems in extreme environments due to their high accuracy and structural stability. However, the effect of temperature variations on the capacitance characteristics of M-μHRGs has not been fully investigated, which is crucial for optimizing the performance of the gyro. This study aims to systematically analyze the effect of temperature on the static and dynamic capacitances of M-μHRGs. In this study, an M-μHRG structure based on a 16-tooth metal oscillator is designed, and conducted simulation experiments using non-contact capacitance measurement method and COMSOL Multiphysics 6.2 finite element simulation software in the temperature range of 233.15 K to 343.15 K. The modeling analysis of the static capacitance takes into account the thermal expansion effect, and the results show that static capacitance remains stable across the measured temperature range, with minimal effect from temperature. The dynamic capacitance exhibits significant nonlinear variations under different temperature conditions, especially in the two end temperature intervals (below 273.15 K and above 313.15 K), where the capacitance values show local extremes and fluctuations. In order to capture this nonlinear behavior, the experimental data were smoothed and fitted using the LOESS method, revealing a complex trend of the capacitance variation with temperature. The results show that the M-μHRG has good capacitance stability in the mid-temperature range, but its dynamic performance is significantly affected at extreme temperatures. This study provides a theoretical reference for the optimal design of M-μHRGs in high- and low-temperature environments.

Appraising the corrosion inhibitory efficacy and adsorption mechanism of leaf extract of Datura discolor on low-carbon steel in low pH media via gravimetric experiments and AFM analysis

BackgroundThe study investigated the inhibitory action of Datura discolor leaf extract against the corrosion of low-carbon steel in 0.5 M solutions of three acids. The purpose was to ascertain the effect of extract concentration, immersion time and temperature variation on corrosion inhibitory efficiency, and to relate to existing reports which show that organic molecules in most plant extracts inhibit corrosion. Extraction of the leaves was done by maceration using methanol, and solvent was removed by evaporation to dryness. Classical gravimetric (mass loss) experiments were used, and experimental data were fitted to adsorption isotherm models to ascertain the best approximation. Surface examination of the low-carbon steel substrates was carried out using the atomic force microscope.ResultsInhibitory protective efficiency of extract was found to appreciate with increasing Datura discolor leaf extract concentration at a fixed temperature, with values ranging 77.6–88.8%, 91.35–98.08% and 19.64–44.64% in H2SO4, HCl and HNO3 solutions respectively at 27 °C. Elevation of temperature was found to depreciate the inhibitor efficiency at constant inhibitor concentration. Best isotherm model fitting was obtained with Langmuir model both at 27 °C and 60 °C and in all the hostile media, while Temkin model gave good approximation only at 60 °C and in H2SO4 and HCl solutions only. The negative values of free energy of adsorption (ΔGads0)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\Delta G_{{{\ ext{ads}}}}^{0} )$$\\end{document} suggested that the adsorptive interaction of the inhibitor with the substrate surface was very spontaneous. Values of ΔGads0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta G_{{{\ ext{ads}}}}^{0}$$\\end{document} were all consistent, fluctuating between − 16.35 and − 17.63 kJ mol−1 in both H2SO4 and HCl solutions, and between − 9.76 and − 10.25 kJ mol−1 in HNO3 solution, and this suggests that adsorption of the inhibitor molecules occurred via physisorption. Values of the activation energy of the corrosion reaction (Eact)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(E_{{{\ ext{act}}}} )$$\\end{document} are all < 40 kJ mol−1, suggesting that the inhibition occurred by a physical adsorption mechanism.ConclusionsThe study concludes that Datura discolor crude leaf extract suppressed the corrosion reactions, and the inhibition was found to arise from the physisorptive interaction of the organic molecules with the substrate/solution interface, forming a stabilize inhibitor film on the substrate surface as revealed by the atomic force micrographs.

Analysis of Tubular NF Plants in Scotland Indicates That Summer Temperatures and Redox-Sensitive Elements Are Correlated with Membrane Biofouling and Shortened Useful Life.

We investigate the effects of seasonal variations in water composition and temperature on the performance of two full-scale drinking water treatment plants in Scotland, equipped with tubular cellulose acetate nanofiltration membranes. Multiple environmental and water quality parameters, recorded over a 4.5-year period, were correlated against membrane permeance, cleaning frequency, and useful life. Membrane autopsies enabled the characterization of the foulant composition. Temporal variations in temperature at plant X led to significant biofouling (manifested by permeance losses of 30-50%, and bacteria detected on the membrane surface) during the summer months, when water temperatures exceeded 20 °C and microbiological activity was highest. Plant Y, in contrast, displayed smaller seasonal variations and was operationally stable without significant fouling. A pronounced increase in manganese and iron (up to 200 and 600 μg/L, respectively) in the lake water at plant X in summer was accompanied by elevated content (∼60 mg/m2) of those metals on the membrane surface, which was consistent with lake thermal stratification and metal input from the sediment into the water column. Our work shows that membrane plants in regions supplied by standing surface water bodies, such as plant X, are more vulnerable to biofouling, especially during warmer months.

High-Q coupled topological edge state in 1D photonic crystal mirror heterostructure for ultrasensitive thermal sensing

This work explores a novel 1D topological photonic crystal (PC) mirror heterostructure for high-performance thermal sensing. The design leverages a unique coupled topological edge state mode (CTES) exhibiting exceptional light confinement at the interface, characterized by a record-high quality (Q) factor. The study investigates the effects of nematic liquid crystal (NLC) integration and temperature variations to enhance functionality. Two NLC defect configurations are explored: complete replacement of silica layers and localized replacement within one topological PC. In both scenarios, the CTES mode exhibits tunability in frequency and Q factor due to the thermo-optic properties of the NLC. This dynamic control offers advantages for various applications beyond thermal sensing, including filtering and switching. The first NLC configuration achieves an outstanding Q factor of 107, surpassing the intrinsic value. Additionally, it demonstrates exceptional thermal sensitivity (−0.12317 nm/°C) and a remarkable figure of merit (1002.48 °C−1). These superior sensing characteristics are attributed to the strong light localization at the interface and the intensified light-matter interaction facilitated by the NLC. The second configuration offers a trade-off between sensitivity and tunability, exhibiting a Q factor in the 106 range, a sensitivity of −0.05853 nm/°C, and a figure of merit of 86.53 °C−1. This study presents a groundbreaking design for 1D topological PC mirror heterostructures with integrated NLC. This platform holds immense promise for developing high-performance, tunable narrowband filters and ultrasensitive thermal sensors, paving the way for advancements in diverse photonic applications.

An Experimental Study of an Autonomous Heat Removal System Based on an Organic Rankine Cycle for an Advanced Nuclear Power Plant

The present study focuses on the recovery of waste heat in an autonomous safety system designed for advanced nuclear reactors. The system primarily relies on passive safety condensers, which are increasingly integrated into the design of advanced Pressurized Water Reactors (PWRs). These condensers are typically immersed in large water tanks that serve as heat sinks and are placed at sufficient heights to ensure natural circulation. Such a heat removal system can operate for an extended period, depending on the size of the tank. This research is driven by the potential to recover part of the energy stored in the boiling water volume, using it as a heat source for an Organic Rankine Cycle (ORC) system via an immersed heat exchanger. The electricity generated by the ORC engine can be used to power the system components, thereby making it self-sufficient. In particular, a pump replenishes the water tank, ensuring core cooling for a duration no longer limited by the water volume in the tank. An experimental test setup, including a boiling water pool and an ORC engine with an electrical output of approximately several hundred watts, along with an immersed evaporator, was constructed at CEA (Grenoble, France). Several test campaigns were conducted on the experimental test bench, exploring different configurations: two distinct ORC working fluids, cold source temperature variation effects, and relative positioning of the submerged evaporator and heat source within the water tank impact. These tests demonstrated the reliability of the system. The results were also used to validate both the ORC condenser and evaporator models. This article presents this innovative system, which has recently been patented. Moreover, to the best of our knowledge, the investigated configuration of an ORC that includes an immersed evaporator is original.

Nonlinear performance of aerospace face gear-planetary gear transmission system under multi-factors including the effect of temperature

Face gear-planetary gear transmission system combines the advantages of both planetary and face gears. And has enormous advantages in the aerospace field. The meshing of gear teeth generates heat through friction, resulting in thermal deformation and affects nonlinear dynamic characteristics. Exploring the temperature effect on the nonlinear dynamics of the transmission system of face gear-planetary gear is of great significance. Considering the temperature variations effect and time-varying meshing stiffness, tooth side clearance as well as meshing error, a nonlinear dynamic model of the face gear-planetary gear system is established. The nonlinear dynamic characteristics of the system were described by maximum Lyapunov exponent diagram, phase diagram, bifurcation diagram et al. The findings indicate that the effect of temperature variations on the gear system is related to the values of the time-varying mesh stiffness coefficient and mesh damping ratio. When the mesh damping ratio is small, the influence of temperature changes on the bifurcation characteristics of the system is more obvious. As the time-varying mesh stiffness value increases, the temperature rise gradually stabilizes in the range of 15°C to 42°C; Under certain temperature changes, as the meshing damping ratio and time-varying meshing stiffness coefficient increase, the face gear planetary gear system gradually tends to stabilize.

Studying the effect of ambient temperature variations on perovskite precursor film formation using different antisolvents

This study investigates the sensitivity of two antisolvents to ambient temperature fluctuations during the fabrication of triple-cation perovskite thin films. Chlorobenzene (CB) and ethyl acetate (EA) were employed as antisolvents in the preparation of perovskite solar cells (PSCs) under identical ambient temperature variation conditions. The experimental results reveal that the quality of the perovskite films does not exhibit a consistent trend in response to ambient temperature changes depending on the antisolvent used. When CB was used as the antisolvent, the highest-performing device, produced at an ambient temperature of 18 °C, achieved a power conversion efficiency (PCE) of 19.9 %. In contrast, when EA was employed as the antisolvent, the highest-performing device was fabricated at 25 °C, reaching a PCE of 20.5 %. Furthermore, when the ambient temperature exceeded 30 °C, all films prepared with either antisolvent exhibited significant cracking, indicating that elevated temperatures adversely affect perovskite film formation. To further investigate the mechanism through which ambient temperature affects the film-forming process, antisolvents at varying temperatures were used during perovskite film preparation to simulate transient temperature increases during formation. This study reveals that the impact of ambient temperature variations on perovskite film formation does not exhibit a uniform trend but is significantly influenced by the choice of antisolvent. Moreover, this work offers valuable insights for optimizing the fabrication of high-quality perovskite thin films.

Impact of ice growth on the physical and chemical properties of dense cloud cores

We investigated the effect of time-dependent ice growth on dust grains on the opacity and hence on the dust temperature in a collapsing molecular cloud core, with the aim of quantifying the effect of the dust temperature variations on ice abundances as well as the evolution of the collapse. To perform the simulations, we employed a one-dimensional collapse model that self-consistently and time-dependently combines hydrodynamics with chemical and radiative transfer simulations. The dust opacity was updated on the fly based on the ice growth as a function of the location in the core. The results of the fully dynamical model were compared against simulations run with different values of fixed ice thickness. We found that the ice thickness increases quickly and reaches a saturation value (as a result of a balance between adsorption and desorption) of approximately 90 monolayers in the central core (volume density ~104 cm−3), and several tens of monolayers at a volume density of ~103 cm−3, after only a few 105 yr of evolution. The results thus exclude the adoption of thin (approximately ten monolayer) ices in molecular cloud simulations except at very short timescales. However, the differences in abundances and the dust temperature between the fully dynamic simulation and those with a fixed dust opacity are small; abundances change between the solutions generally within a factor of two only. The assumptions on the dust opacity do have an effect on the collapse dynamics through the influence of the photoelectric effect on the gas temperature, and the simulations take a different time to reach a common central density. This effect is, however, small as well. In conclusion, carrying out chemical simulations using a dust temperature corresponding to a fixed opacity seems to be a good approximation. Still, although at least in the present case its effect on the overall results is limited – as long as the grains are monodisperse – ice growth should be considered to obtain the most accurate representation of the collapse dynamics. We have found in a previous work that considering a grain size distribution leads to a complicated ice composition that depends on the grain size nonlinearly. With this in mind, we will carry out a follow-up study where the influence of the grain size on the present simulation setup is investigated.

Spatial and temporal distribution patterns of ants (Hymenoptera: Formicidae) in Gobi Desert ecosystems, Northwest China

Ants (Hymenoptera: Formicidae) represent the most critical arthropod community in desert ecosystems, where interactions among vegetation, soil, and climate dictate ant assemblages. Nonetheless, our understanding of how various factors influence desert ant assemblages across different spatial and temporal scales remains limited. Therefore, this study aims to analyse the temporal and spatial distribution patterns of desert ants and to determine the effects of precipitation and temperature variations on ant assemblages. To achieve this, we continuously monitored the monthly dynamics of ants at 72 uniform 8m × 8m grid points in the Gobi Desert ecosystem of Northwest China from 2015 to 2020 using pitfall traps. The results indicated that Messor desertus and Cataglyphis aenescens were the dominant ant species, with significant annual and monthly variations in the number of individuals captured from 2015 to 2020. In 2020, monthly captures of M. desertus exhibited a bimodal pattern, peaking in November, whereas those of C. aenescens exhibited a unimodal pattern, peaking in June. Annual data revealed that population size was significantly positively correlated spatially at a distance of 24 meters. Semi-variance analysis and Moran’s I indicated that structural factors predominantly controlled the ant assemblages at a small scale from 2015 to 2020. Annual catches of desert ants tended to decrease with increasing annual precipitation, while an opposite trend was rising average annual temperatures. In conclusion, variations in annual and monthly precipitation and temperature influenced the temporal response patterns of desert ants, thereby altering their spatial assemblages.

Micellar-enhanced ultrafiltration of heavy metal wastewater with palygorskite under various temperatures and pressures

The micellar-enhanced ultrafiltration process demonstrated significant potential for treating heavy-metal-contaminated wastewater. Operating conditions greatly influence complex formation and ultrafiltration efficiency, suggesting that optimizing these parameters could enhance both the process's effectiveness and its cost-efficiency. In this research, nano-palygorskite was used to treat wastewater contaminated with Cu2+, Zn2+, and Cd2+. The material was characterized using SEM, FTIR, XRD, and Zeta potential, and the effects of temperature and pressure variations on the process were investigated. Under conditions of pH 7.0 and 0.1 MPa, the retention rates of the three heavy metal ions rapidly equilibrated within 40 min, achieving removal efficiencies of 99.94 %, 99.75 %, and 99.56 %, respectively. Temperature changes significantly influenced the retention rates, which increased by approximately 5 % with increasing temperature. At pH 7.0 and 293 K, increasing the pressure improved the retention rates by approximately 3 %, reaching 99.31 %, 98.63 %, and 99.19 %, respectively. The experimental data fit the pseudo-2nd-order kinetic equation and Langmuir isotherm adsorption model, with maximum adsorption capacities of 10.44 mg/g, 9.41 mg/g, and 11.36 mg/g, respectively. Overall, gradual increases in the temperature and pressure accelerated the reaction rate, highlighting their beneficial effects on MEUF. This study underscores the potential of palygorskite as an effective inorganic complexing agent for heavy-metal-contaminated wastewater treatment.

On ablation characteristics based on two-temperature model involving a multivariate lattice heat capacity by ultrashort laser-irradiated in zirconia

To explore the mechanism of material removal, this paper conducts a systematic study on picosecond laser processing of zirconia by using both theory and experiment. Comparing the multivariate lattice heat capacity of the Einstein and Debye models, two-temperature model (TTM) is developed to improve the accuracy of the temperature field. Then, to verify the effectiveness of TTM proposed, ablation experiments are performed by single-pulse picosecond laser on zirconia at different laser energy density. The results show that the measured craters profiles are well agree with the simulated melting/vaporization temperature distribution. Micro-morphology is significantly affected by phase transition induced by temperature rise. Moreover, the results confirmed that increased temperature can lead to transition in zirconia crystal structure and oxygen vacancies. Finally, the effect of coupling temperature variations on the elemental and physical phase variations are focused to investigate, which can help to optimize the processing quality due to crystalline phase transitions. This study provides guidance for optimizing picosecond laser processing of zirconia.

Multi-Modal Sensing Ionogels with Tunable Mechanical Properties and Environmental Stability for Aquatic and Atmospheric Environments.

Ionogels have garnered significant interest due to their great potential in flexible iontronic devices. However, their limited mechanical tunability and environmental intolerance have posed significant challenges for their integration into next-generation flexible electronics in different scenarios. Herein, the synergistic effect of cation-oxygen coordination interaction and hydrogen bonding is leveraged to construct a 3D supramolecular network, resulting in ionogels with tunable modulus, stretchability, and strength, achieving an unprecedented elongation at break of 10800%. Moreover, the supramolecular network endows the ionogels with extremely high fracture energy, crack insensitivity, and high elasticity. Meanwhile, the high environmental stability and hydrophobic network of the ionogels further shield them from the unfavorable effects of temperature variations and water molecules, enabling them to operate within a broad temperature range and exhibit robust underwater adhesion. Then, the ionogel is assembled into a wearable sensor, demonstrating its great potential in flexible sensing (temperature, pressure, and strain) and underwater signal transmission. This work can inspire the applications of ionogels in multifunctional sensing and wearable fields.

Environmental Factors Associated With Fish Reproduction in Regulated Rivers

ABSTRACTHumans have extensively altered rivers to accommodate anthropogenic uses. Dams modify river flow and temperature regimes important for lotic fish reproduction. Yet, assessments of fish production in relation to environmental conditions in regulated rivers are lacking but are needed to guide experimental environmental flows. We evaluated the effects of water temperature and discharge on larval Catostomidae, Sciaenidae, and Clupeidae production to inform environmental flow management. We sampled ichthyoplankton from April through June on the Des Moines and Iowa rivers prior to (2014–2015) and after (2021–2022) an experimental environmental flow was incorporated on the Des Moines River. We used a hurdle model to assess the effects of water temperature, discharge, and discharge variation on larval presence (logistic regression) and density (linear regression). Larval Catostomidae were captured once water temperatures exceeded 15°C, Sciaenidae appeared when water temperature surpassed 18°C, while Clupeidae appeared when water temperature exceeded 20°C. The probability of larval Sciaenidae and Clupeidae presence increased with discharge variation while densities were both positively associated with discharge and discharge variation. The probability of Sciaenidae and Catostomidae larval presence increased with water temperature. Interactions between water temperature and discharge influenced Clupeidae presence and Catostomidae density. The probability of Clupeidae presence increased with discharge at warmer water temperatures. Catostomidae densities increased with discharge at cool water temperature (13°C) and decreased with discharge at warm (25°C) temperatures. Our results provide information about the effects of discharge, discharge variation, and water temperature driving larval fish production in anthropogenically altered rivers to guide environmental flow management.

The effect of temperature variation on the transient response of RF PIN diode limiters for very high frequency applications

AbstractThis work presents the effect of temperature change on the capacitance of silicon PIN diodes and the resulting change in performance of RF limiters at very high frequency (VHF). Device temperatures were varied between −25 ºC and 100 ºC, with small‐signal parameters (including device capacitance) extracted at regular temperature increments and bias voltages from −20 Vdc to +3 Vdc using a multi‐bias parameter extraction method. It was found that the junction capacitance of the four PIN diodes under investigation increases with temperature, as expected from carrier lifetime behaviour, while results also confirmed prior observations of an inverse relationship between forward‐biased series resistance and temperature. Devices were subsequently tested in two different limiter topologies through high‐power transient measurements. It was found that the combination of increased capacitance and decreased resistance with increasing temperature increases the transient spike leakage and decreases the flat leakage of a limiter. It was also concluded that, for VHF, an anti‐parallel topology provides the best performance over a wide range of temperatures.

The Phase Distribution Characteristics and Interphase Mass Transfer Behaviors of the CO2-Water/Saline System under Gathering and Transportation Conditions: Insights on Molecular Dynamics.

In order to investigate the interphase mass transfer and component distribution characteristics of the CO2-water system under micro-scale and nano-scale transport conditions, a micro-scale kinetic model representing interphase mass transfer in the CO2-water/saline system is developed in this paper. The molecular dynamics method is employed to delineate the diffusion and mass transfer processes of the system's components, revealing the extent of the effects of variations in temperature, pressure, and salt ion concentration on interphase mass transfer and component distribution characteristics. The interphase mass transfer process in the CO2-water system under transport conditions can be categorized into three stages: approach, adsorption, and entrance. As the system temperature rises and pressure decreases, the peak density of CO2 molecules at the gas-liquid interface markedly drops, with their aggregation reducing and their diffusion capability enhancing. The specific hydration structures between salt ions and water molecules hinder the entry of CO2 into the aqueous phase. Additionally, as the salt concentration in water increases, the density peak of CO2 molecules at the gas-liquid interface slightly increases, while the density value in the water phase region significantly decreases.

Effect of temperature on braking performance of the comb-type disc magnetorheological brake

To investigate the effect of internal temperature variation of the comb-type disc magnetorheological brake on braking performance, firstly we simulate the temperature field analysis of magnetorheological brake by using the finite element method, and verify the reasonableness of the simulation using experiments. Secondly, the temperature variation of comb magnetorheological brakes during intermittent 5 min braking and continuous braking and the effect of temperature on the braking torque were investigated experimentally. The experimental results show that as the number of braking increases, the maximum temperature inside the brake increases until saturation, while the braking torque decreases. This research helps to enhance the realization of braking stability over the effective operating temperature range.

Dispersion of thermoelastic guided waves in multi-layered porous media

The mechanical properties of the graphite electrode will dynamically change during the charge-discharge cycle, which will affect the propagation characteristics of guided waves in lithium-ion batteries. Meanwhile, lithium-ion batteries experience fluctuations in operating temperature during cycling, which will also influence the propagation of guided waves. This research aims to investigate the guided wave propagation problem of porous electrode material with electrolyte versus temperature. The problem is under the framework of Green-Naghdi theory and Biot theory, and a numerical approach is presented to solve the thermoelastic wave propagation characteristics in such a multi-layered porous electrode. A frequency domain simulation for a multi-layered porous anode will be established. The simulation results confirm the feasibility and accuracy of the proposed approach. The porosity of the anode material shows obvious dynamic variation during cycling, which illustrates a strong correlation with the elastic modulus of the solid skeleton. Then, the effects of porosity and temperature variations on the propagation characteristics of thermoelastic guided waves in multi-layered porous graphite electrodes will be analyzed in detail. The phase velocity of fundamental modes appears regularly shift in the low frequency range. This may provide theoretical support for the acoustic nondestructive characterization of the operating states of the lithium-ion batteries.

Thermo-micromechanical finite element modelling of tyre–pavement interaction under UAE environmental conditions

ABSTRACT This work presents a finite element model of the thermo-mechanical behaviour of tyre–pavement interaction, focusing on the effects of temperature variations in the UAE on skid resistance under various tyre operating conditions. The pavement is modelled as multiple layers to account for the stiffness contribution of each layer. The top asphalt layer is modelled at a microscale level to consider its various constituents such as air voids, aggregates and binder. Moreover, the model accounts for the viscoelastic properties of tyre and pavement, considering their dependence on time and temperature. The finite element simulations of a rolling tyre over the pavement have been carried out under different tyre operating conditions and various temperature cases reflecting the winter, spring, and summer seasons in the UAE. The simulation results show that the maximum level of skid resistance occurs during the winter season and thereafter drops by a significant amount during the summer. This research provides good insights about the seasonal variation of skid resistance in the UAE, which enhances road safety.