Instantaneous Temperature Research Articles

Estimation of battery temperature during drive cycle operation by the time evolution of voltage and current

During the operation of electric vehicles, accurate temperature monitoring of lithium-ion batteries by battery management system is crucial to their safety. However, temperature sensors possess limitations as they necessitate regular calibration to avoid inaccuracies, which can be challenging to accomplish in certain scenarios. As an alternative, a general sensorless temperature estimation framework is developed in this study to either serve as a complementary approach alongside sensors or function independently to ensure reliable temperature measurement. The proposed framework relies solely on data regarding battery voltage and current measurements, and this information is employed to determine the parameters of the equivalent circuit model via the vector-type recursive least squares algorithm in the first step. In the second step, these parameters and the voltage/current data serve as the input to the deep neural network (DNN) to estimate the instantaneous battery surface temperature during dynamic driving cycles under various ambient temperatures and degradation scenarios. To reflect the effect of past battery operation on the current temperature, a newly defined current integral function is proposed, by which the input time length of the DNN model is suggested. Four combinations of the model input are studied, and the best input option yields an average estimation error of the battery temperature that falls below 0.5 °C.

An efficient viscoelastic multiscale model for investigation on the cure‐induced microscopic residual stresses of composite laminates

AbstractThe cure‐induced residual stresses have a significant influence on the deformation and mechanical properties of composites. Moreover, the cure‐induced residual stresses exhibit multi‐level and multiscale distributions due to the complexity of micro‐structure of composites and anisotropic characteristics. In this paper, a computationally efficient multiscale procedure is proposed to predict the microscopic residual stresses induced by cure temperature, cure shrinkage and macroscopic residual stresses, which is based to the linear viscoelastic theory combined with the micro‐mechanics method. The instantaneous microscopic residual stresses are expressed as a linear combination of the instantaneous temperature increment, degree of cure increment and macroscopic strain increment at all times of the cure process until to the current time. The proposed method is verified in comparison with the published results in literature and the microscale FEA at different length scales, respectively. The results show that the proposed method is about a thousand times faster than directly using FEA in the microscale RVE model once the influence coefficient matrices are determined. At length, the microscale stresses of all nodes of the entire macroscale model are examined by using the proposed method. It is found that the thermal‐chemical‐mechanical loads lead to serious microscopic stresses for the matrix and interphase constituents, especially for those due to the macroscopic residual stresses.Highlights Microscale residual stress is written as a linear combination of macroscale loads. Applying macroscale loads on microscale FEA model to obtain influence matrices. The presented model avoids repeatedly FEA microscopic to improve the efficiency. The online time required for the proposed model is much less than microscale FEA. The microscale stress increases the risk of matrix cracking and interface bonding.

Asymmetric nanofiber photothermal interactive electronic skin with triboelectric autonomous thermal perceptivity

Thermal-perceptive electronic skins (e-skin) represent an important functional interface in wearables and soft robots. Realizing an all-in-one structured nanofiber interactive e-skin with autonomous thermal perceptivity remains challenging. We demonstrated a polyurethane/(polyvinyl pyrrolidone/MXene) (PPM) bilayer nanofiber film with asymmetric structure compactness by continuous and controllable electrospinning, that achieves asymmetric optical transmittance (visible light transparency of 20∼97%, infrared transparency of 5.5∼34.1%) and photothermal actuation response, with a response rate of 0.8 mm−1 s−1 and bending curvature of 2.2 cm−1, as well as additional excellent triboelectric outputs of ∼320 V and ∼5.4 µA. We proposed a “contact-actuation-perception” strategy for instantaneous object temperature sensing based on the PPM, which can actuate under photothermal stimulation to change its contact area with the target objects at different temperatures, producing temperature-dependent distinguishable triboelectric signals for autonomous thermal perception, with sensitivity up to ∼99.6%. This work could inspire a facile strategy to realize asymmetric features in fiber materials, in which the asymmetric optical-thermal-mechanical-electrical coupling mechanism for active perception is expected to promote the development of autonomous interactive e-skins.

Instantaneous thermometry imaging using two-photon laser-induced fluorescence.

Measuring temperature in complex two-phase flows is crucial for understanding the dynamics of heat and mass transfer. In this Letter, we introduce a novel, to the best of our knowledge, optical approach based on the combination of two-photon laser-induced fluorescence (2p-LIF) imaging and two-color laser-induced fluorescence (2CLIF) for instantaneous temperature mapping of complex liquid media. Using Kiton Red (KR) and Rhodamine 560 (R560), a temperature sensitivity of 1.54%/∘C has been achieved over a range of 17-60°C. The monitoring of two-dimensional transient temperature dynamics in the heating and degassing of water shows the efficiency of the 2p-2CLIF. This new approach contributes to the toolkit of optical temperature measurement techniques, providing a robust solution for studying transient scattering media and high-speed two-phase flows.

Observation and analysis of the ultra-rapid cooling effect of cryoprotectant droplets on a sapphire surface

Cryopreservation has emerged as a promising technology to realize semipermanent storage of biomaterials widely used in assisted reproduction and cell therapy. A large portion of successful cryopreservation requires the combination of ultra-rapid cooling and appropriate low-toxicity cryoprotectant agents, which inhibits the formation of ice crystals that damages the cells lethally. Conventional approaches are not competent in accurately capturing high enough cooling rate and more importantly, not able to simultaneously track the instant appearance of the sample at a microscale level during the momentary cooling process. A rapid freezing device for the droplet sample study purpose was designed and developed, which is capable of visualization of the sample on a sapphire surface at a vitrification cooling rate over 104 K/min. The instantaneous temperature changes and the appearance of the cooling samples were recorded at the speed of 10 kHz and 2000 frames. Typical vitrification and crystallization processes were observed and analysed. Low concentrations of the CPA solution inhibited the formation and growth of the crystals, and resulted in the formation of layered ice, punctate ice and scattered small ice. The experimental results could contribute to a better understanding of the ultra-rapid cooling mechanism on cryoprotectant droplets.

Multi-point thermometry tool and in-situ measurement of temperature fields

In-situ real-time measurement of instantaneous milling temperature distribution is a key issue to realize efficient machining. For the foregoing reasons, the milling model of Inconel 718 was established, and the cloud diagram of tool temperature distribution during milling was obtained. A multi-point temperature measurement tool for milling temperature with an integrated thin-film temperature sensor was designed. The real-time temperature distribution of the tool during milling was obtained from 27 sets of milling tests. The impact of each milling parameter on the milling temperature was analyzed by ANOVA.

Simultaneously quantitative and qualitative regulation of active sites of Ni-phyllosilicate for enhanced CO2 hydrogenation to methane

To address the problems of low metal utilization rate and poor low-temperature activity of the nickel phyllosilicate catalysts for CO2 methanation, this work prepared ultrathin defect-rich Ni-phyllosilicate through ball milling method in the presence of H2O2 modifier, which simultaneously created active sites with more quantity and higher quality. The instantaneous temperature and high pressure derived from the collision and friction of grinding balls provided driving force for the Ni-phyllosilicate synthesis, and the shear force destroyed the interlayer forces to construct the ultrathin layers. H2O2 molecule could insert the layers and dissociate to O2 bubbles, whose cavitation effect created holes and defects in the nickel phyllosilicate nanosheets and SiO2 spheres. H2O2 amount was crucial for the defect construction and the optimum Ni-AA-1H catalyst possessed the ultrathin nanosheet of 0.68 nm and high Ni dispersion of 15.6 %, whose TOFCO2 reached 3.76 × 10−2 s−1 at 160 °C. The in-situ DRIFTS results confirmed the enhanced low-temperature activity and the HCOO− reaction pathway over Ni-AA-1H for CO2 methanation. Nickel precursor effect was also investigated, and nickel acetylacetonate was determined as the optimal one compared with nickel acetate and nickel chloride, owing to the high steric effect of CH3COCHCOCH3− group and strong basicity environment during ball milling process.

Millisecond activity modulation of atomically-dispersed Fe–N–C catalysts

Precious-metal-free transition metal–N–C catalysts containing atomic MeNx centers are promising candidates for the oxygen reduction reaction (ORR) in rechargeable zinc-air batteries. In this study, we report the highly efficient synthesis and activity modulation of Me–N–C (Me = Fe, Co, Ni, and Cu) catalysts utilizing the flash Joule heating technique, accomplished within 200 milliseconds. The instantaneous high temperature (∼3535 K) and rapid heating and cooling rates (above 104 K s–1) induce the formation of atomically-dispersed MeNx sites on the surface of carbon nanotube matrices. This ultrafast thermal shock process not only prevents the aggregation of isolated metal atoms but also achieves catalytic activity modulation through heteroatom engineering. Typically, phosphorus atoms play a crucial role in suppressing nitrogen loss and regulating the local coordination environment of FeNx centers, thereby facilitating the 4 e– electrocatalytic reduction of oxygen. As expected, the phosphorus-doped Fe–N–C catalyst exhibits excellent ORR activity with a high half-wave potential of 0.904 V and a low Tafel slope of 23.1 mV dec–1 in a 0.1 M KOH medium. The assembled zinc-air battery demonstrates a prominent power density of 236.3 mW cm–2 and desirable long-term durability over 400 h, surpassing that of the Pt/C+IrO2-based battery.

Iron Active Center Coordination Reconstruction in Iron Carbide Modified on Porous Carbon for Superior Overall Water Splitting.

In this work, a novel liquid nitrogen quenching strategy is engineered to fulfill iron active center coordination reconstruction within iron carbide (Fe3C) modified on biomass-derived nitrogen-doped porous carbon (NC) for initiating rapid hydrogen and oxygen evolution, where the chrysanthemum tea (elm seeds, corn leaves, and shaddock peel, etc.) is treated as biomass carbon source within Fe3C and NC. Moreover, the original thermodynamic stability is changed through the corresponding force generated by liquid nitrogen quenching and the phase transformation is induced with rich carbon vacancies with the increasing instantaneous temperature drop amplitude. Noteworthy, the optimizing intermediate absorption/desorption is achieved by new phases, Fe coordination, and carbon vacancies. The Fe3C/NC-550 (550 refers to quenching temperature) demonstrates outstanding overpotential for hydrogen evolution reaction (26.3mV at -10 mAcm-2) and oxygen evolution reaction (281.4 mV at 10mAcm-2), favorable overall water splitting activity (1.57 V at 10 mAcm-2). Density functional theory (DFT) calculations further confirm that liquid nitrogen quenching treatment can enhance the intrinsic electrocatalytic activity efficiently by optimizing the adsorption free energy of reaction intermediates. Overall, the above results authenticate that liquid nitrogen quenching strategy open up new possibilities for obtaining highly active electrocatalysts for the new generation of green energy conversion systems.

Transient heat conduction in multi-material topology optimization of thermoelastic structures involving dynamic constraints

This work presents a modified solid isotropic material with penalization (SIMP) for conducting dynamic-constrained multi-material topology optimization (MMTO) of thermoelastic structures subjected to transient thermal conduction. The novelty of this study is the multi-material optimization of instantaneous temperature conduction under specific frequency constraints, which has never been studied before. The proposed method has been developed for general models of multi-material interpolations such as thermal stiffness, heat capacity, and thermal stress coefficient. The temperature environment is formulated by applying prescribed mechanical and thermal loads that are exposed over a period of time. In this work, we focus on the objective of minimizing compliance in a transient heat conduction structure while simultaneously imposing constraints on the dynamics. With high temperatures, the stiffness of the optimization results decreases while stability is still guaranteed. The sensitivity of the objective function is subsequently calculated using the discretize-then-differentiate approach for the dynamic problem as well as the adjoint variable method. This study examines the impact of thermal fields and different time increments in conjunction with dynamic criteria. The outcomes of heat conduction result in notable alterations under identical dynamic constraint levels.

Analysis of Grindability and Surface Integrity in Creep-Feed Grinding of High-Strength Steels.

Creep-feed grinding of high-strength steel is prone to excessive wheel wear and thermal damage defects, which seriously affects the service performance of parts. To solve the above-mentioned issue, a creep-feed grinding test was carried out on high-strength steel using SG and CBN abrasive wheels. The grindability of high-strength steel was scrutinized in terms of grinding force, machining temperature and grinding specific energy. Moreover, the effects of operation parameters and grinder performances on the surface integrity of the workpiece such as surface morphology, roughness, residual stress and hardness were rigorously studied. The results indicate that, when the instantaneous high temperature in the grinding area reaches above the phase transition temperature of the steel, the local organization of the surface layer changes, leading to thermal damage defects in the components. The outstanding hardness and thermal conductivity of CBN abrasives are more productive in suppressing grinding burns than the high self-sharpening properties of SG grits and a more favorable machining response is achieved. The effects of thermal damage on the surface integrity of high-strength steel grinding are mainly in the form of oxidative discoloration, coating texture, hardness reduction and residual tensile stresses. Within the parameter range of this experiment, CBN grinding wheel reduces grinding specific energy by about 33% compared to SG grinding wheel and can control surface roughness below 0.8 µm. The weight of oxygen element in the burn-out workpiece accounts for 21%, and the thickness of the metamorphic layer is about 40 µm. The essential means of achieving burn-free grinding of high-strength steels is to reduce heat generation and enhance heat evacuation. The results obtained can provide technical guidance for high-quality processing of high-strength steel and precision manufacturing of high-end components.

A Self-Temperature Compensation Barometer Based on All-Quartz Resonant Pressure Sensor.

This paper reports a self-temperature compensation barometer based on a quartz resonant pressure sensor. A novel sensor chip that contains a double-ended tuning fork (DETF) resonator and a single-ended tuning fork (SETF) resonator is designed and fabricated. The two resonators are designed on the same diaphragm. The DETF resonator works as a pressure sensor. To reduce the influence of the temperature drift, the SETF resonator works as a temperature compensation sensor, which senses the instantaneous temperature of the DETF resonator. The temperature compensation method based on polynomial fitting is studied. The experimental results show that the accuracy is 0.019% F.S. in a pressure range of 200~1200 hPa over a temperature range of -20 °C~+60 °C. The absolute errors of the barometer are within ±23 Pa. To verify its actual performance, a drone flight test was conducted. The test results are consistent with the actual flight trajectory.

Fast and robust demodulation of temperature from sparse sapphire fiber Bragg grating spectra with machine learning

Sapphire fiber Bragg gratings (FBGs) have demonstrated their efficacy in sensing at high-temperature harsh environments owing to their elevated melting point and outstanding stability. However, due to the extremely high volume of modes supported by the clad-less sapphire fiber, the demodulation capability of the reflected spectra is hindered due to their irregular and somewhat complicated shapes. Hence, a mode-stripping or scrambling step is typically employed beforehand, albeit at the expense of sensor robustness. Additionally, conventional interrogation of sapphire FBG sensors relies on an optical spectrum analyzer due to the high sensitivity provided by the spectrum analyzer, where the long data acquisition time restricts the system from detecting instantaneous temperature variations. In this study, we present a simple sensor configuration by directly butt-coupling the sapphire FBG multi-mode lead-out fiber to a single-mode lead-in fiber, and detect its reflected spectra via a low-cost, fast, and coarsely resolved (166 pm) spectrometer. We leverage machine learning to compensate for the under-sampling of the measured FBG spectra and achieve a temperature accuracy of 0.23 °C at a high data acquisition rate of 5 kHz (limited by the spectrometer). This represents a tenfold improvement in accuracy compared to conventional peak-searching and curve-fitting methods, as well as a significant enhancement in measurement speed that enables dynamic sensing. We further assess the robustness of our sensor by attaching one side of the sensor to a vibrator and still observe good performance (0.43 °C) even under strong shaking conditions. The introduced demodulation technology opens up opportunities for the broader use of sapphire FBG sensors in noisy and high-temperature harsh environments.

The influence of laser-annealing pulse width on optical transparency and carrier dynamics of ITO thin films

Indium tin oxide (ITO) has important application in photoelectronic and photonic devices, demanding effective approach and appropriate parameters to modulate the ITO properties. The effects of laser annealing at 1064 nm with different pulse width (875 ps, 10 ns, and 300 ns) on optical and nonlinear optical properties of ITO films were investigated. Compared with 875 ps and 10 ns, laser annealing at 300 ns significantly improved the near-infrared transmittance of ITO films. The change arises from the elimination of oxygen vacancies and reduction of tin oxides, resulting in the decrease of carrier concentration. Finite element simulations indicate that laser annealing with pulse width of 875 ps and 10 ns have high instantaneous peak temperatures of 1128.5 K and 783 K, respectively, while the temperature accumulation between pulses is negligible. On the contrary, the laser annealing with a pulse width of 300 nshas lower peak transient temperature of 343 K but high static residence temperature of 973 K. The results reveal that the modification of ITO films depends more on the static average temperature rather than the instantaneous peak temperature. The modulation of carrier dynamics in both amplitude and temporal domain was demonstrated after 300 ns laser annealing, achieving ultrafast transient response approximately 150 fs. This work provides theoretical and experimental basis for us to select suitable laser conditions for directional annealing of ITO film to make it suitable for the applications of broad optical spectrum photovoltaic devices or ultrafast optical exchange for high-speed data processing.

A Digital Twin Development Framework for an Electrical Submersible Pump (ESP)

Premature failure of a sub-system can be critical for an industrial Cyber-Physical System (CPS). A digital twin (DT) assisted predictive maintenance procedure can reduce the risk of costly unplanned maintenance. This study presents a generalized DT development framework for an Electrical Submersible Pump (ESP) that can assist in predictive maintenance. The framework is applied on a single-phase ESP as a proof of concept. The maximum winding temperature of the selected ESP is simulated using a multiphysics simulation tool with transient electromagnetic and transient heat transfer solvers. The simulation parameters were refined using data captured through an ESP free-run experiment. Simulating the total energy loss in the ESP stator and rotor and the transfer of heat from the outer fluid domain facilitates a relationship between the measurable external temperature and the maximum temperature in the stator winding. Following a design of experiments (DOE) approach, a series of simulations were run to establish a statistical model for the winding temperature in terms of the fluid temperature, the time duration a particular temperature was persistent, and the initial maximum stator winding temperature. As the instantaneous maximum stator winding temperature is related to the remaining useful lifetime, it was shown using a case study that the proposed framework can prognosticate the ESP failure, assisting effective decision-making for predictive maintenance of a CPS.

The Coupled Temperature Field Model of Difficult-to-Deform Mg Alloy Foil High-Efficiency Electro-Rolling and Experimental Study

In response to the challenging difficult-to-deform of magnesium foils, a high-efficiency and high-precision electro-rolling temperature field coupled model is established. This model is designed to simulate the non-annealing electric rolling (NAER) process of Mg foils under conditions of high current density, rapid temperature rise rates, and large temperature gradients. Firstly, a coupled temperature field difference model for the guide roller, roll, and Mg foil is established, based on the equipment for NAER and the electrification conditions. The Joule heat, distortion heat, and friction heat in the electric rolling process were precisely considered. Secondly, considering the peculiarity of the heat source and the heat transfer mechanism during NAER, the influence of the dynamic boundary conditions on the instantaneous temperature of the Mg foil was analyzed, which was closer to the actual situation. The experimental results show that the original model can accurately simulate the transient temperature change in Mg foils during NAER, and the error between the predicted value and the measured value is within 7.1%. According to the calculation of the model, the microstructure of completely recrystallized magnesium foil with a grain size of 4.61 μm and a texture strength of 11.3 can be obtained at an inlet temperature of 250 °C.

Unraveling the Nano-Bio Interface Interactions of a Lipase Adsorbed on Gold Nanoparticles under Laser Excitation.

The complex nature and structure of biomolecules and nanoparticles and their interactions make it challenging to achieve a deeper understanding of the dynamics at the nano-bio interface of enzymes and plasmonic nanoparticles subjected to light excitation. In this study, circular dichroism (CD) and Raman spectroscopic experiments and molecular dynamics (MD) simulations were used to investigate the potential changes at the nano-bio interface upon plasmonic excitation. Our data showed that photothermal and thermal heating induced distinct changes in the secondary structure of a model nanobioconjugate composed of lipase fromCandida antarcticafraction B (CALB) and gold nanoparticles (AuNPs). The use of a green laser led to a substantial decrease in the α-helix content of the lipase from 66% to 13% and an increase in the β-sheet content from 5% to 31% compared to the initial conformation of the nanobioconjugate. In contrast, the differences under similar thermal heating conditions were only 55% and 11%, respectively. This study revealed important differences related to the enzyme secondary structure, enzyme-nanoparticle interactions, and the stability of the enzyme catalytic triad (Ser105-Asp187-His224), influenced by the instantaneous local temperature increase generated from photothermal heating compared to the slower rate of thermal heating of the bulk. These results provide valuable insights into the interactions between biomolecules and plasmonic nanoparticles induced by photothermal heating, advancing plasmonic biocatalysis and related fields.

Simulation Analysis and Experimental Research on Electric Thermal Coupling of Current Bearing

With the advancement of industries such as high-speed railways, new energy vehicles, and wind power, bearings are frequently exposed to various electric field environments, leading to the need for lubricating oil films of bearings to withstand voltage. One of the major issues caused by the breakdown discharge process of the lubricating oil film in bearings is the generation of local instantaneous high temperatures. This temperature rise is a key factor contributing to problems such as high operating temperature of bearings, surface damage in the contact area, and degradation of lubrication performance. This research article focuses on the comprehensive influence of bearing friction and electrical factors. It establishes a heat source calculation model and a temperature field simulation model specifically for current-carrying bearings. This study analyzes both the overall temperature rise of bearings and the local temperature rise resulting from breakdown discharge. Furthermore, the accuracy of the simulation analysis is verified through experiments. The temperature field simulation and experimental results consistently indicate that electrical environmental factors can cause an increase in the overall temperature rise of a bearing. Additionally, the breakdown and discharge of the lubricating oil film generate local instantaneous high temperatures in the contact area of the bearing.

Validation of symmetry-induced high moment velocity and temperature scaling laws in a turbulent channel flow.

The symmetry-based turbulence theory has been used to derive new scaling laws for the streamwise velocity and temperature moments of arbitrary order. For this, it has been applied to an incompressible turbulent channel flow driven by a pressure gradient with a passive scalar equationcoupled in. To derive the scaling laws, symmetries of the classical Navier-Stokes and the thermal energy equationshave been used together with statistical symmetries, i.e., the statistical scaling and translation symmetries of the multipoint moment equations. Specifically, the multipoint moments are built on the instantaneous velocity and temperature fields other than in the classical approach, where moments are based on the fluctuations of these fields. With this instantaneous approach, a linear system of multipoint correlation equationshas been obtained, which greatly simplifies the symmetry analysis. The scaling laws have been derived in the limit of zero viscosity and heat conduction, i.e., Re_{τ}→∞ and Pr>1, and they apply in the center of the channel, i.e., they represent a generalization of the deficit law, thus extending the work of Oberlack etal. [Phys. Rev. Lett. 128, 024502 (2022)0031-900710.1103/PhysRevLett.128.024502]. The scaling laws are all power laws, with the exponent of the high moments all depending exclusively on those of the first and second moments. To validate the new scaling laws, the data from a large number of direct numerical simulations (DNS) for different Reynolds and Prandtl numbers have been used. The results show a very high accuracy of the scaling laws to represent the DNS data. The statistical scaling symmetry of the multipoint moment equations, which characterizes intermittency, has been the key to the new results since it generates a constant in the exponent of the final scaling law. Most important, since this constant is independent of the order of the moments, it clearly indicates anomalous scaling.

Tooth surface analysis method based on thermo-mechanical coupling and its application in prediction of gear dry-running bearing capacity

In gear transmission, the continuous meshing of the teeth will lead to an increase in their temperature, which will have a certain impact on the working performance of the tooth surface. In order to explore the failure-bearing capacity of gears under dry-running conditions, temperature effects were considered in existing methods for determining tooth surface failure, making it more suitable for high-temperature working conditions caused by a lack of lubrication. The failure situation of gears within 35 min after losing lubrication was analyzed. The results indicate that when the gear loses lubrication, the tooth surface temperature of the gear pair has exceeded the material melting point after working at an input power of 2000 kW for 12 min. But when the power drops to 1000 kW, the instantaneous temperatures of the driving and driven gear tooth surfaces at the end of 35 min reach 1090 and 995°C, respectively, which are lower than the scuffing temperature of the tooth surface. The cumulative wear depths of the driving and driven gear tooth surfaces at the end of 35 min were 239 and 86.6 um, respectively, which were lower than the failure wear depth of the tooth surface; The allowable contact stress of the gear pair within 35 min is greater than its contact stress, meeting the judgment condition of no pitting failure. This indicates that reducing power can appropriately extend the failure time of gear teeth, thereby improving the ultimate working capacity of gears under dry-running conditions. In addition, a gear dry-running experiment was carried out. By comparing the theoretical calculation results with the measured gear failure degree, it shows that the improved method for determining gear surface failure is effective.