Thermal Effects Research Articles

Short-term thermal exposure effects on growth rate, photosynthetic performance, and chemical composition in Pyropia spiralis (Rhodophyta) from the brazilian coast: insights and limitations

Short-term thermal exposure effects on growth rate, photosynthetic performance, and chemical composition in Pyropia spiralis (Rhodophyta) from the brazilian coast: insights and limitations

Evaluation of thermal performance and vibration effects on automotive headlights for selection of heat sink geometry

Evaluation of thermal performance and vibration effects on automotive headlights for selection of heat sink geometry

Efficient activation of Co/SBA-15 catalyst by high-frequency AC-DBD plasma thermal effect for toluene removal

Efficient activation of Co/SBA-15 catalyst by high-frequency AC-DBD plasma thermal effect for toluene removal

The optimization method of wing plasma ice shape regulation based on quantitative assessment of flight risk

Plasma ice shape regulation is a technology which uses plasma actuator to regulate the continuous ice into safer intermittent ice by its significant thermal effect with limited energy. Whether plasma ice shape regulation could reduce flight risk is a new problem under the wing with continuous ice. The 3D printed ice shapes were arranged on the leading edge of the wing based on NACA0012 airfoil, aiming to simulate the configuration after ice shape regulation. And the aerodynamic parameters were obtained by wind tunnel experiments. The experimental results showed that the ratio of signal regulation ice width d\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d$$\\end{document} to chord length of the wing bA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$b_{A}$$\\end{document} determined the aerodynamic characteristics, and the aerodynamic characteristics changed better compared with configuration of the continuous ice. However, the flight risk of the wing under given regulation ratio is unknown. Based on the straight and swept wing after regulating, the flight safety boundaries were simulated by the reachable set method. Further, a method of quantitative assessment of flight risk is proposed. Quantitative values of risk were calculated. The results show that the flight risk all decreases from level 2 to level 4 compared with configuration of the continuous ice when d/bA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d/b_{A}$$\\end{document} equals 0.15 under conditions of swept and straight wing.

Seismic Response Study of S-Wave Incident Stratified Unsaturated Soil Site Under Thermal Effects

ABSTRACT Drawing upon the fundamental principles of mixture continuum and thermodynamics, planar S-wave incident model for layered unsaturated soil is formulated. Employing the Helmholtz vector decomposition principle, the wave field within the layered unsaturated soil is analyzed using the transfer matrix method, accounting for the influence of thermal effects. An analytical solution is obtained for the seismic response in layered unsaturated soil under the action of thermal effect. The results of the numerical analyses show that the thermo-physical parameters such as relative heat of solid, temperature, and thermal expansion coefficient have a notable effect on the seismic response of the site.

Investigating of epoxy nanocomposites structure and properties that contain both pristine and aminosilane-treated silicon carbide (SiC) particles

This article presents a methodology for functionalization of silicon carbide (SiC) through chemical modification using γ-aminopropyltriethoxysilane (APTES) and its subsequent dispersion in an epoxy composition. The research revealed that functionalizing SiC particles with γ-aminopropyltriethoxysilane (SiC(APTES)) enhanced their chemical compatibility with the epoxy composition, facilitating the dispersion of SiC particles. Furthermore, it was observed that the functionalization of the filler had a profound impact on the structure, curing kinetics, and physical and mechanical properties of epoxy nanocomposites. The addition of SiC(APTES) into the epoxy composition resulted in a significant reinforcement of the material. Specifically, the flexural stress and flexural modulus of elasticity increased by 179% and 74%, respectively, while the impact strength experienced a remarkable improvement of 462%. Additionally, the tensile strength and tensile modulus of elasticity increased by 83% and 70%, respectively, compared to the epoxy composite without SiC. The application of SiC(APTES) also played a crucial role in initiating the polymerization process through the involvement of reactive amino groups, leading to a reduction in the initial curing temperature and an amplification of the thermal effects of the polymerization reaction. Moreover, the presence of functionalized SiC significantly influenced the structure of the epoxy composite, thereby contributing to its enhanced strength. In summary, the inclusion of SiC in the epoxy composition not only bolstered the material but also improved its thermal stability.

Low-temperature direct diffusion bonding of Zr702 alloys via electric current assistance

Integrated zirconium (Zr) alloy fuel claddings require low-temperature and high-efficiency joining technologies for nuclear applications. However, conventional direct-joining technologies make it challenging to satisfy critical requirements at relatively low temperatures in a short time. As a promising alternative, the electric-current-assisted joining (ECAJ) method was studied to reduce the joining temperature and time required for the direct joining process. ECAJ was performed on a spark plasma sintering apparatus, with the specimens assembled with and without graphite dies in the two models. The microstructural evolution and mechanical properties of Zr/Zr joints were investigated at 600 − 900 °C for 1 s to 30 min under a pressure of 30 MPa using different configurations with or without a graphite die. While the joint quality varied with the joining conditions, no significant phase transformation, abnormal grain growth, or preferential orientation was observed at the interface. The maximum shear strength of 404 ± 78 MPa and hardness of 370.9 ± 49.8 HV were achieved at 600 °C for 10 min using a die-less configuration. The joining mechanism was discussed in terms of the potential thermal and electric effects inside the specimen, with the low-temperature joining mechanism attributed to the combined effect of transient overheating and electric-field-accelerated element self-diffusion at the interface, with the latter playing a leading role.

Non-linear thermal radiation and heat transfer effect on MHD flow of a micropolar fluid through a porous medium

Non-linear thermal radiation and heat transfer effect on MHD flow of a micropolar fluid through a porous medium

Molecular dynamics investigation of wear mechanisms in drilling motion for FeCrNiCoAl high-entropy alloy

This work employed molecular dynamics (MD) to investigate the wear mechanism in the drilling motion of FeCrNiCoAl high entropy alloy. MD simulations reveal a reduction in tangential force upon applying torque to the tool, attributed to the synergy between rotational and thermal effects. Entropy generation analysis indicates that below 20GHz, rotational effects prevail, while conversely, thermal effects take precedence. Furthermore, the correlation between wear volume and rotation frequency exhibits non-monotonic characteristics, which suggests that fine-tuning material wear can be achieved through adjustments to the rotation frequency. An in-depth analysis of the strain energy and the Bejan number allows the categorization of wear into three modes: rotation-dominant, transitional, and thermal-dominant.

Wood sandwich softening behavior via coupling of moisture and heat

The controllability of the position and thickness of the compressed layer in the sandwich compression wood is primarily based on the yield stress distribution during a hydrothermal treatment. In this study, the variation law of the yield stress of poplar wood was analyzed in the moisture content (MC) range of absolute dryness to saturation and the temperature range of 30 to 210℃. A prediction model of wood yield stress response to MC and temperature was developed and the formation of sandwich compression was analyzed. The yield stress of the wood was influenced by the thermal effect and plasticizing effect. In the process of increasing temperature and MC, the yield stress decreased gradually. And the yield stress change rate was 0.29–0.46MPa in the MC range of 5–10%. The prediction model of wood yield stress was developed by a multiple linear regression analysis. This example demonstrated that coupling distributions of MC and temperature were formed upon heating at 180℃, which led to a gradient distribution of the glass transition temperature and yield stress inside the wood. This phenomenon resulted in the sandwich softening behavior under the coupling of moisture and heat, which was the key formation mechanism of sandwich compressed wood.

Optimization of MTI structure based on material characteristics under extreme aerodynamic heating environment

Thermal insulation structure is a key factor to protect a high-speed aircraft to work safely and complete various tasks. The multilayer thermal insulation (MTI) structure has attracted much attention because of its light weight and good thermal insulation effect. The performance of an MTI structure is not only related to its physical sizes, but also closely related to the material optimization and temperature influences. A transient nonlinear thermal transfer model of the MTI structure is established, and a numerical solution strategy of the nonlinear thermal transfer model is proposed. Considering material selection, introducing the temperature influence of materials, and taking the geometric dimensions and equivalent mechanical properties of the MTI structures as constraints, an optimization frame of the MTI structures is established. Then two intelligent methods are adopted to solve the problem. Using the aerodynamic heating environment of X-43 flight trajectory, the results of a typical high-speed aircraft show that the proposed optimization framework can reduce the structural mass density from 13.95 kg‧m−2 to 9.10 kg‧m−2 by about 34.8 %. The temperature effect analysis shows that the temperature variation has an important influence on the optimization results. If the temperature effect on material properties is not considered, the optimized design scheme may not meet the temperature design constraints (The maximum temperature of the inner surface is 410 K, far exceeding the maximum allowable temperature of 320 K) which further leads to structural failures. Finally, the reliability and rationality of the optimization scheme are verified by a finite element model (FEM). The equivalent modulus of the optimized MTI structure is 146 GPa and the mass area density of the MTI structure is 7.7 kg‧m−2. The optimization design method of an MTI structure proposed in the current paper provides a technical support and lays a foundation for the overall design of a high-speed aircraft.

Ultrafast modulable 2DEG Huygens metasurface

Huygens metasurfaces have demonstrated remarkable potential in perfect transmission and precise wavefront modulation through the synergistic integration of electric resonance and magnetic resonance. However, prevailing active or reconfigurable Huygens metasurfaces, based on all-optical systems, encounter formidable challenges associated with the intricate control of bulk dielectric using laser equipment and the presence of residual thermal effects, leading to limitations in continuous modulation speeds. Here, we present an ultrafast electrically driven terahertz Huygens metasurface that comprises an artificial microstructure layer featuring a two-dimensional electron gas (2DEG) provided by an AlGaN/GaN heterojunction, as well as a passive microstructure layer. Through precise manipulation of the carrier concentration within the 2DEG layer, we effectively govern the current distribution on the metasurfaces, inducing variations in electromagnetic resonance modes to modulate terahertz waves. This modulation mechanism achieves high efficiency and contrast for terahertz wave manipulation. Experimental investigations demonstrate continuous modulation capabilities of up to 6 GHz, a modulation efficiency of 90%, a transmission of 91%, and a remarkable relative operating bandwidth of 55.5%. These significant advancements substantially enhance the performance of terahertz metasurface modulators. Importantly, our work not only enables efficient amplitude modulation but also introduces an approach for the development of high-speed and efficient intelligent transmissive metasurfaces.

Innovative rapid liquid concentration measurement based on thermal lens effect and machine learning

This study addresses the critical need for rapid and online measurement of liquid concentrations in industrial applications. Although the thermal lens effect (TLE) is extensively explored in laser systems for determining thermal lens focal lengths, its application in quantifying solution concentrations remains underexplored. This research explores the relationship between various liquid concentrations and the interference fringes induced by the TLE. A novel approach is introduced, utilizing TLE to measure solution concentrations, with integration of image processing and discrete Fourier transform (DFT) techniques for feature extraction from interference rings. Further, machine learning, specifically backpropagation artificial neural network (BP-ANN), is employed to model concentration measurement. The model demonstrates high accuracy, evidenced by low root mean square error (RMSE) values of 3.055 and 5.396 for the training and test sets, respectively. This enables precise, real-time determination of soy sauce concentration, offering significant implications for industrial testing, environmental monitoring, and other related fields.

Controlled photothermal ablative processing of commercial polymers minimizing undesired thermal effects under high frequency femtosecond laser irradiation

The response of three commercial polymers (poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET) and polypropylene (PP)) with different thermal properties under high repetition rates (1 kHz-1 MHz) with femtosecond (450 fs) multi-pulse laser irradiation at λ = 515 nm (1.4 J/cm2) is reported resulting in a complete study with controlling the ablation depth and minimizing collateral thermal effects. Tunable ablation depth is achieved accurately by varying the repetition rate at a constant fluence. The results are compared to a photothermal model that aims at explaining the heat accumulation effect of successive pulses as a function of the repetition rate and predicts three different heat regimes (non-cumulative, cumulative and saturation). The threshold frequencies for each regime can be estimated from the model, providing control for selecting frequency values and thermal regimes. Thermal analyses are performed to characterize the materials, concluding that thermal parameters are vital for selecting optimal materials and laser processing parameters.

Plate interface geometry complexity and persistent heterogenous coupling revealed by a high-resolution earthquake focal mechanism catalog in Mentawai, Sumatra

Geometry and frictional states of the megathrust in subduction zones play critical roles on the rupture extent, hence the magnitude, of great earthquakes. However, their details are often difficult to obtain, primarily due to limited offshore geophysical observations. Here we overcome this challenge by precisely determining source parameters (i.e., location and focal mechanism) of medium-sized earthquakes using global broadband seismic waveform data. The dip angles of 108 Mw 5.0+ plate interface events from 1990 to 2017 in the central Sumatran subduction zone are tightly constrained by waveform inversion, and their locations are refined with surface-wave relocation and depth phases modeling. Our results reveal compact trench parallel earthquake belts at the up-dip and down-dip boundaries of the ruptures of the Mentawai 2007 Mw 8.4 and Mw 7.9 earthquakes. The down-dip seismicity belt marks ∼8º bending of the plate interface, suggesting that the change of fault geometry may have played a role in halting the megathrust rupture along with thermal effects. The up-dip seismicity belt shows a clear spatial complementarity to the largest events’ slip distribution. This belt is quite narrow (∼20 km) for the Mw 8.4 rupture but much broader (∼50 km) for the Mw 7.9 event. The combination of the up-dip seismicity belt and slip distributions matches well with the positive residual bathymetry and gravity anomalies, suggesting that these events resulted from long-term coupling on the plate boundary. Our findings suggest the importance of considering both up-dip and down-dip seismicity belts, along with residual bathymetry and gravity data, in understanding megathrust rupture behaviors and assessing the associated hazards.

Evaluation of Thermal Radiation Blocking Effect of Water Mist Curtain in Fire of Hazardous Material Storage Tank

In this study, the thermal radiation blocking effect of a water mist curtain in a full-scale hazardous material storage tank fire was numerically simulated. A fire dynamics simulator (FDS) was used for the numerical simulation, and the accuracy of the heat flux prediction of the FDS was verified using an earlier experimental study on a full-scale hazardous material storage tank fire. Subsequently, a water mist curtain system was installed in a full-scale hazardous material storage tank, and the effects of fire source conditions and water mist curtain characteristics on the heat flux and thermal radiation blocking rate of the water mist curtain were examined. The results of the numerical simulation showed that the water mist curtain decreased the heat flux and increased the thermal radiation blocking rate when the fire source was a tank and dike and when the nozzle had a large spray angle and a small droplet size. Near the adjacent protected tank (in the height of 2∼14 m from the ground at the nozzle installation position), the thermal radiation blocking rate of the water mist curtain was measured to be 62.5∼72.4% and 33.5∼67.4% for the tank and dike fire and the tank fire, respectively, 62.5∼72.4% and 54.4∼65.3% for the spray angles of 180° and 90°, respectively, and 62.5∼72.4% and 71.2∼83.0% for the droplet sizes of 400 and 200 µm, respectively. This study confirmed that the water mist curtain could effectively block the thermal radiation from the fire tank to the adjacent tanks during a full-scale hazardous material storage tank fire.

Finite element simulation and experimental investigation of in-situ laser-assisted diamond turning of monocrystalline silicon

While the effectiveness of in-situ laser-assisted diamond turning (In-LAT) for promoting the ductile machinability of monocrystalline silicon has been demonstrated, the underlying cutting mechanisms remain inadequately understood. In this study, we investigate the fundamental mechanisms involved in the In-LAT of monocrystalline silicon by finite element (FE) simulations and experiments. Specifically, a FE model of In-LAT of monocrystalline silicon is developed, which incorporates a Drucker–Prager constitutive model to address the brittle fracture of the material, as well as temperature-dependent materials properties to address the thermal softening effect. Furthermore, experiments of In-LAT of monocrystalline silicon are conducted with the self-developed In-LAT device, including tapering cutting and end face cutting. Simulation results demonstrate that In-LAT significantly increases the critical depth of cut for the brittle-to-ductile transition of monocrystalline silicon in tapering cutting mode by 72.2% compared to conventional cutting, accompanied with significantly reduced cutting forces, continuous chip profile and reduced surface brittle damage. The promotion of ductile machinability of monocrystalline silicon under In-LAT is attributed to the reduction and dispersion of stress in the cutting zone, which is in contrast to the significant stress concentration at the rake face and cutting edge in conventional cutting. And simulation results also provide an optimal temperature field of 900 K for the In-LAT of monocrystalline silicon, above which the excessive plastic flow accompanied by thermal accumulation results into deteriorated surface roughness. These findings provide valuable insights for understanding the cutting mechanisms of In-LAT and the parameter optimization for In-LAT application.

Employment of Finite Element Analysis Method to Analyze the Thermal Effects of Direct Energy Deposition on SUS316L

Employment of Finite Element Analysis Method to Analyze the Thermal Effects of Direct Energy Deposition on SUS316L

Operando Decoding of Surface Chemical and Thermal Events in Photoelectrocatalysis via a Lab-Around-Microfiber Sensor.

Operando decoding of the key parameters of photo-electric catalysis provides reliable information for catalytic effect evaluation and catalytic mechanism exploration. However, to capture the details of surface-localized and rapid chemical and thermal events at the nanoscale in real-time is highly challenging. A promising approach based on a lab-around-microfiber sensor capable of simulating photo-electric catalytic reactions on the surface of optical fibers as well as monitoring reactant concentration changes and catalytic heat generation processes is demonstrated. Due to the penetration depth of submicron size and the fast response ability of the evanescent field, the lab-around-microfiber sensor overcame the difficulty of reading instantaneous surface parameters in the submicron range. This sensor operando dismantled the changes in reactant concentration and temperature on the catalyst surface induced by light and voltage, respectively. It also decoded the impact of catalyst composition on the adsorption efficiency and catalytic efficiency across various wavelengths and determined the synchronized occurrence of pollutant degradation and catalytic thermal effects. Stable correlations between the real-time parameters and catalytic activities are obtained, helping to provide a basic understanding of the catalytic process and mechanism. This approach fills an important gap in the current monitoring methods of catalytic processes and heat production.

CO2, Ar, and He dilution effects on combustion dynamics and characteristics in a laboratory-scale combustor

This study aimed to investigate the impact of CO2, Ar, and He addition on combustion instability under varying acoustic frequencies, dynamic pressure amplitudes, and light emission intensities. Experiments involved using pure methane as fuel at a 1.0 equivalence ratio, with three distinct acoustic frequencies. The burner operated at 5 kW, and the combustion chamber was excited at frequencies of 90 Hz, 160 Hz, and 320 Hz. It was observed that with dilution, the temperatures decreased more from the burner exit temperature to the exhaust section. As the oxygen concentration in the oxidizer decreases in Ar, He, and CO2 dilution, CO emissions increase, but CO2 emissions decrease. The addition of Ar, He, and CO2 causes an effect that reduces the flame temperature and brightness while causing the flame length to extend due to the diluting effect. While a decrease in instability was observed in He-Ar-CO2 dilution in 20 % oxygen, instability increased again in the three 19 % cases. It is observed that mixtures under the diluent effect approach the blowoff limit due to the increase in ignition delay. It has been determined that the addition of diluent increases the tendency for the flame to go out, especially due to the thermal effect. The methane fuel with an 18 % oxygen concentration in the oxidizer of Ar remained below lean extinction limits, undergoing blowoff. The temperature was measured as 1156 K at 21 % oxygen concentration, 584 K at 19 % oxygen concentration for carbon dioxide, 877 K for Helium, and finally 777 K for argon. In the case of pure air for the combustion of methane, CO emissions were measured at 140 ppm. Average CO levels at 20 % oxygen concentration in the oxidizer are 1254 ppm, 356 ppm, and 308 ppm with carbon dioxide, argon, and helium, respectively. The study also shows that an increase in O2 in oxidizing air leads to a decrease in CO emissions, while an increase in He/Ar/CO2 gases leads to an increase in CO emissions. Regarding NOX emissions, undiluted conditions measured a value of 14 ppm. NOX emission levels approached 0 ppm in all dilution cases and achieved its goal.