Decreasing Temperature Research Articles

Photovoltaic panel cooling with new composite of phase change materials and hierarchical nanoparticles

In this research, the use of a new type of phase change materials (PCM) and hierarchical nanoparticles is discussed to improve the electrical and thermal efficiency of PV panels. TiO2/CuO hierarchical nanoparticles are synthesized by hydrothermal method, and PCMs containing nanoparticles (2.5–10%wt) are prepared, and then experiments are performed in indoor conditions under solar simulator light. The PV panel with a maximum nominal power of 30W is used. The new PCM is made from a mixture of lauryl alcohol and beeswax (LABW). A spiral heat exchanger is placed in the PCM container, in which the flow rate of cool water is variable (m˙ = 0.002–0.01 kg s−1). Firstly, the temperature and voltage-current changes of the PV panel with time are investigated without using PCMs as a reference case, and in steady-state conditions, the temperature and output power values are 67.34 °C and 22.33W. The use of LABW compared to pure beeswax leads to a significant decrease in the PV panel temperature and as a result, an increase in its electrical and thermal efficiency. Also, adding nanoparticles to PCMs from 2.5 % to 7.5 %wt due to the improvement of their thermal conductivity and increasing the heat storage rate of the PV panel leads to an increase in its electrical and thermal efficiency. There is no significant change to decrease the temperature and increase the production capacity of PV panels by increasing the percentage of nanoparticles from 7.5 % to 10%wt. The maximum production power, electrical and thermal efficiency of the PV panel at a flow rate of 0.01 kg s−1, 10%wt of nanoparticles, and a radiation intensity of 1000 W m−2 are 28.92 W, 12.55 %, and 76.67 %, respectively.

Experimental study on the cold-start performance of a gas heating assisted air-cooled proton exchange membrane fuel cell stack

Air-cooled proton exchange membrane fuel cells (PEMFCs) have the advantages of simple structure, low parasitic power, and flexible application scenarios. However, it is difficult to warm up the stack under subzero temperatures because excessive air is used as the cooling medium. In this study, the thermal balance inside an air-cooled PEMFC stack during cold start was theoretically analyzed to explore the relationship between the heating power and ambient temperature. Subsequently, the cold-start performance was tested in a climatic chamber. The results showed that the combination of endplate heating and gas heating is a feasible cold-start measure. The theoretical analysis indicated that only 14 % of the stack rated power for preheating can promote a successful cold start at −30 °C, which has also been validated in the ensuing tests. The test results showed that the temperature uniformity and the cell voltage consistency deteriorate as the ambient temperature decreases, while these two indicators can be improved by increasing the gas heating power. As the ambient temperature decreases, the heating power may become too high, resulting in poor cold-start performance. Therefore, if an air-cooled stack is to be started at extreme low temperatures, further research is needed in terms of flow fields and materials.

Point defects in coated diamonds

Twelve coated diamonds from mines in the Siberian craton and the Urals were studied to reconstruct the aggregation mechanisms of nitrogen-related defects in natural unirradiated Ib-IaA diamonds. The diamonds' coats contain the following simple nitrogen and nitrogen-vacancy defects: С (N0), NV−, H2 (NVN−), H3 (NVN0) and A (N=N). The NV− and H2 defects are the most intense in the coats containing C-centres: however, the H2 defect is absent in samples with solely A-centres. The dominance and spatial distribution of negatively charged nitrogen-vacancy defects indicate their key role in the C-to-A nitrogen aggregation process. This aggregation occurred in conjunction with the formation of the N3VH defect. Two previously undescribed systems with zero-phonon lines at 836 nm (1.48 eV) and 525.3 nm (2.36 eV) were identified. The 525.3 nm system is associated with lines at 689, 698 and 904 nm and may be related to Y-centres. The diamonds' coats were formed just before the kimberlitic eruption, which resulted in a sharp temperature decrease and the preservation of rapidly transforming low-aggregated defects in outer zones of the coats.

Experimental study on the shear characteristics of frozen soil‐concrete interface under the constant normal stiffness

AbstractThe interaction between the structure and soil is a crucial factor in infrastructure stabilization in cold region engineering, both transversely and vertically. During interface deformation, the transverse action is reflected in the change of constraints, including normal stiffness, normal stress, and normal volume, while the vertical action is reflected in the change of shear properties. However, the study of different transverse constraints is not systematic, especially considering the normal stiffness and shear properties at different hydrothermal states. This study investigated the shear behavior of the interface between concrete and frozen soil under different normal stiffness, temperature, and water content using the interface direct shear test under temperature‐controlled conditions. The results show that with the increase in temperature and water content, the initial shear stiffness of the interface shear stress‐shear displacement curve gradually increases, and the interface shear strength gradually increases. Different normal stiffnesses have a small effect on the morphology of the interfacial shear stress‐shear displacement curve but significantly affect the peak shear strength. The peak shear strength increases significantly with the increase of normal stiffness, and this trend is more obvious with the decrease in temperature. The corresponding interfacial cohesion and friction angle also increases with the increase in normal stiffness.

ENTROPY-OPTIMIZED FLOW OF COUPLE STRESSES IN AN POROUS INCLINED PIPE WITH UNIFORM MAGNETIC FIELD AND MIXED CONVENTION

Abstract The research aims to investigate the entropy-optimized flow of couple stresses in a porous inclined pipe exposed to a transverse constant magnetic field and mixed convection. It focuses on understanding the thermodynamic efficiency and fluid behaviour under convective boundary conditions, contributing to improved designs in engineering applications where such flows are relevant. The aim is to enhance heat transfer efficiency in industrial processes such as chemical reactors, heat exchangers, and geothermal systems, while also improving filtration systems for applications like water purification and oil recovery. By subjecting the flow to a uniform magnetic field and mixed convection, nonlinear governing equations arise due to mixed convection. We linearize these equations using a quasi-linearization approach and solve them using Chebyshev spectral collocation. Our analysis focuses on thermodynamic phenomena like entropy generation and the Bejan number, which have implications for the efficiency and sustainability of industrial processes. We visualize temperature and axial velocity profiles across various parameter ranges to understand the fluid's behaviour under the influence of magnetic fields and porous materials. As the magnetic parameter increases, there is a decrease in fluid velocity and temperature. However, the opposite tendency is seen for the couple stress viscosity ratio parameter. We also observe irreversibility dominating heat transfer at the pipe wall, while fluid friction irreversibility dominates around the pipe's centre. This research contributes to advancing our understanding of thermodynamic processes in complex fluid systems and has practical implications for optimizing industrial processes and developing more efficient filtration systems.

Real-time microwave transmittance variation of glass fiber composites subjected to laser irradiation

Laser irradiation may have a significant impact on the microwave transmission properties of glass fiber composites. In this study, a two-dimensional microwave transmission transient model of glass fiber composites during the complete laser irradiation process was developed. The numerical results indicate that carbonization during irradiation causes a significant increase in dielectric loss, thus resulting in a decrease in transmittance. After irradiation, the dielectric loss decreased due to the decrease in temperature, which, in turn, led to an increase in transmittance. The increased transmittance after cooling was lower than the original value due to the generation of pyrolytic carbon with a high dielectric loss. The numerical results were verified by conducting an experiment wherein the microwave transmittance of glass fiber composites was measured in real time before, during, and after laser irradiation. In addition, the effects of different laser parameters on the real-time microwave transmittance during laser irradiation were investigated experimentally and numerically. For the same total energy, a laser with a high power density and short irradiation time had a more significant effect on the attenuation of transmittance.

Hot deformation behavior of 30MnB5V steel: Phenomenological constitutive model, ensemble learning algorithm, hot processing map and microstructure evolution

The hot deformation behavior of 30MnB5V steel was experimentally investigated and theoretically analyzed using phenomenological constitutive models and an ensemble learning algorithm. Hot compression experiments were conducted with an MMS-200 thermo-mechanical simulation machine on the 30MnB5V steel at strain rates of 0.01–10 s−1 and temperatures of 950–1150 °C. The characteristics of the true stress-strain curves under different conditions and the corresponding microstructural evolutions were examined in detail. The results indicate that raising the temperature or lowering the strain rate promotes dynamic recrystallization. As temperature decreases or strain rate increases, the degree of recrystallization softening declines, and stress-strain curves transition from recrystallization to sustained work hardening or dynamic recovery types. Subsequently, the strain-compensated Arrhenius model, modified Johnson-Cook (J-C) model, and Bayesian-optimized LightGBM (BO-LightGBM) model were constructed sequentially to predict the flow stress of the tested steel. The accuracy of the three models was evaluated using the coefficient of determination (R2), mean absolute error (MAE), root mean square error (RMSE), and mean absolute percentage error (MAPE). The results reveal that the accuracy of the BO-LightGBM model is significantly higher than that of the Arrhenius model and the modified J-C model. Finally, three-dimensional power dissipation maps and hot processing maps were established under various strain conditions. The results suggest that the tested steel demonstrates good workability at deformation temperatures of 1075–1125 °C and strain rates of 0.03–0.22 s−1.

Magnetism of pseudospin-1/2 pyrochlore antiferromagnet Na3Co(CO3)2Cl.

Pyrochlore magnets have attracted interest as systems for realizing critical phenomena, rich magnetic structures, associated topological band structures, and nontrivial quantum phases. Na3Co(CO3)2Cl is a pseudospin-1/2 antiferromagnet in which the Co2+ions form a pyrochlore network. Its structural and magnetic properties were investigated using magnetization, heat capacity, ESR, single-crystal X-ray diffraction, powder neutron diffraction and powder inelastic neutron scattering. Magnetization and heat capacity measurements indicated a ground-state doublet, which is regarded as pseudospin 1/2, dominated the magnetic properties at low temperatures, with a magnetic exchange of 9.6 K. As the temperature decreases, a magnetic transition is observed at 1.6 K, which is confirmed to be an all-in-all-out magnetic order. The crystal field excitations observed by inelastic neutron scattering experiments indicated the Ising nature of the ground-state doublet. This thorough study revealed that Na3Co(CO3)2Cl can be regarded as a pseudospin-1/2 pyrochlore lattice antiferromagnet with dominant Ising-type interactions.

Simulation study on heat and mass transfer characteristics within tubular moving bed heat exchangers

In the field of waste heat recovery, tubular moving bed heat exchangers (MBHEs) hold great promise as equipment capable of effectively handling large-sized granular materials with high temperature. To further clarify the heat and mass transfer characteristics within tubular MBHEs, this study firstly conducted detailed investigations on the contributions of different heat transfer mechanisms. The result shows that heat radiation (∼45 %) and gas film heat conduction (∼42 %) control the heat transfer processes involving tube walls, with an inlet particle temperature of 600 °C, tube wall temperature of 50 °C, and particle descent velocity of 2 mm/s. These contributions can be influenced by the inlet particle temperature and the tube wall temperature, rather than the particle descent velocity. Additionally, for a specific particle, its heat transfer state is highly depended on where it is located. Subsequently, the time-varying and space-varying characteristics of the heat transfer processes involving tube walls are studied. The results suggest that the time-varying and space-varying characteristics are inherent in tubular MBHEs due to the difficulty to achieve complete stability. Meanwhile, temporal fluctuations intensify with an increase in the inlet particle temperature, a decrease in wall temperature, or an increase in particle descent velocity. The result of power spectral density (PSD) indicates that the heat transfer processes exhibit a degree of chaotic behavior due to the nonlinear property of sub-models, as well as the randomness in particle feeding and contacts. The space-varying characteristic is mainly determined by the inlet particle temperature and the tube wall temperature, rather than the particle descent velocity. This characteristic can be observed in both the axial and circumferential directions, with the circumferential variation being more pronounced than the axial variation. Furthermore, a double-tube MBHE, a topic that has received scant attention in previous research, is investigated in comparison to a single-tube MBHE to explore the differences in heat and mass transfer between the two configurations. It indicates that under the same boundary conditions, there are differences in heat transfer results, which are attributed to the interactions between two vertically arranged tubes. These interactions are reflected in the reconstruction of particle flow patterns and the effect altering the temperature distribution for the particles or fluid surrounding the tubes. The obtained results provide valuable insights into the mass and heat transfer behaviors of particles and fluids within tubular MBHEs, laying a foundation for advancing the development of efficient tubular MBHEs.

Near-surface ocean temperature and air-sea heat flux observed by a buoy array during summer to autumn in year 2014 in the northern South China Sea

The observational data of the air-sea interface and upper ocean elements from a buoy array deployed in the northern South China Sea from June to November 2014 is analyzed. The COARE 3.0 algorithm was adopted to examine the variability of air-sea heat fluxes and their contributions to near-surface ocean temperature changes. During the observation period, air-sea heat exchange in the northern South China Sea is primarily determined by solar shortwave radiation and latent heat flux, with net heat flux mostly negative, indicating that the ocean predominantly loses heat. In autumn, net heat flux loss significantly increased by an average of 34.4 W/m2, primarily due to enhanced latent heat loss driven by stronger winter monsoon. During typhoon period, net air-sea heat flux was significantly suppressed, mainly due to reduced solar shortwave radiation, with minimal contribution from sensible heat flux. Near-surface ocean temperature exhibited a seasonal cooling trend, averaging 29.7°C in summer and 28.4°C in autumn. The maximum cooling during typhoon reached 3.1°C, with minimal contribution from air-sea heat flux. During the monsoon transition period, weaker winds led to a slight increase in near-surface ocean temperature, with air-sea heat flux contributing 70.2% and 56.3% to this process. During winter monsoon, more uniform water column mixing resulted in a gradual decrease in near-surface ocean temperature, with air-sea heat flux contributing over 60% to this process.

Aerosol effects during heat waves in summer 2022 and responses to emission change over China

This study explores aerosol direct, indirect, and feedback effects on meteorology and fine particulate matter during heat waves of August 2022 over eastern China by using an online coupled regional climate–chemistry–aerosol model. In this period, aerosols exerted mean direct (DRE) and indirect (IRE) radiative effects of −3.9 Wm−2 and −2.4 Wm−2 at TOA, which totally caused a decrease in average surface air temperature by 0.3 °C over east China, accompanied by decreases in PBLH (planetary boundary layer height) and precipitation and an increase in PM2.5 concentration. With the anthropogenic emission reduction from 2013 to 2022, DRE apparently decreased while IRE changed little, leading to a decrease in total aerosol radiative effect (TRE) by 27% at TOA. The weakened TRE resulted in increases in surface air temperature and precipitation by 0.14 °C and 2.7 mm, respectively, on average over east China, with the maximum warming exceeding 0.5 °C in BTH (Beijing–Tianjin–Hebei province). This study highlights a warming trend due to weakened TRE, which may exacerbate heat wave, and an increasing importance of aerosol IRE relative to DRE due to weak sensitivity of cloud properties to aerosol change during the emission reduction.

Strain rate and temperature‐dependent shear fracture mechanism of high‐energy propellant/liner interface zone

AbstractThe shear fracture of the high‐energy propellant/liner interface zone occurs in many application cases of solid rocket motors (SRMs). The shear fracture experiment development is thus a crucial issue. Here we aim to study the shear fracture mechanism of the interface zone under varying strain rates and temperatures. Shear experiments are carried out using self‐made specimens containing prefabricated cracks. Force‐displacement curves, experimental images, and fracture surface topographies are obtained at different strain rates and temperatures. The strain field of the specimen surface is analyzed using the digital image correlation (DIC) method. Additionally, the fracture surface topographies are analyzed using ImageJ software. The results show that the shear mechanical properties of the interface zone are strongly dependent on strain rates and temperatures. Specifically, the shear fracture strength and failure displacement exhibit a decrease with increasing temperature and an increase with increasing strain rate. The DIC analysis shows that the fracture strain of the interface zone typically ranges from 0.4 to 0.6. The analysis of the fracture surface topographies reveals that the shear fracture modes are predominantly mixed fractures, including propellant/liner interface fractures and propellant cohesive fractures. Since the propellant/liner interface is more sensitive to strain rate and the propellant is more sensitive to temperature, the propellant/liner interface fracture ratio increases from 1.99 % to 60.26 % with decreasing strain rate and temperature. The results show that the experimental method can effectively be used to study the shear fracture mechanism of the high‐energy propellant/liner interface zone.

Simulation of a cold spell in Guangdong-Hong Kong-Macao Greater Bay Area with WRF: Sensitivity to PBL schemes

The selection of the planetary boundary layer (PBL) parameterisation schemes is crucial for the simulation of local meteorology, especially under extreme weather events. A suitable PBL scheme is one of the key conditions to accurately reproduce the real weather conditions. In this study, the performance of all the three available PBL schemes that can be coupled with the multi-layer urban canopy model in the Weather Research and Forecasting (WRF) model: Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), and Bougeault-Lacarrere (BL), is evaluated for a cold spell event with Guangdong-Hong Kong-Macao Greater Bay Area (GBA) as the study region. It is found that accurate prediction of the strength of the vertical mixing and the change in wind speeds over the upper atmosphere is critical for reproducing the nighttime temperatures during the cold spell. The simulations of the BL scheme are consistent with observations that wind speeds do not vary much during daytime and nighttime, thus exhibiting strong vertical mixing and slowing down the near-surface temperature decrease during nighttime. The MYJ and YSU schemes cause significant underestimation of the nighttime 2-m temperature due to significant overestimation of the nighttime upper-air wind speeds, which leads to more heat transport through horizontal advection and hinders vertical mixing and convective activities. The results confirm that selection of a suitable PBL scheme can effectively reduce the uncertainty of the simulation results, and the coupling of the BL scheme with the multi-layer urban canopy model can better simulate the cold spell events occurring in the GBA, which also provides valuable references for the simulation of other similar coastal cities.

Twist Angle-Dependent Phonon Hybridization in WSe2/WSe2 Homobilayer.

The emerging moiré superstructure of twisted transition metal dichalcogenides (TMDs) leads to various correlated electronic and optical properties compared to those of twisted bilayer graphene. In such a versatile architecture, phonons can also be renormalized and evolve due to atomic reconstruction, which, in turn, depends on the twist angle. However, observing this reconstruction and its relationship to phonon behavior with conventional, cost-effective imaging methods remains challenging. Here, we used noninvasive Raman spectroscopy on twisted WSe2/WSe2 (t-WSe2) homobilayers to examine the evolution of phonon modes due to interlayer coupling and atomic reconstruction. Unlike in the natural bilayer (NB), ∼0° as well as ∼60° t-WSe2 samples, the nearly degenerate A1g/E2g mode in the twisted samples (1-7°) split into a doublet in addition to the nondegenerate B2g mode, and the maximum splitting is observed around 2-3°. Our detailed theoretical calculations qualitatively capture the splitting and its dependence as a function of the twist angle and highlight the role of the moiré potential in phonon hybridization. Additionally, we found that around the 2° twist angle, the anharmonic phonon-phonon interaction is higher than the natural bilayer and decreases for larger twist angles. Interestingly, we observed anomalous Raman frequency softening and line-width increase with the decreasing temperature below 50 K, pointing to the combined effect of enhanced electron-phonon coupling and cubic anharmonic interactions in moiré superlattice.

Experimental Comparison of Glazed and Unglazed Hybrid Solar Modules Considering Power Productivity and Cell Temperature

AbstractThis study presents the effect of cell temperature on the hybrid solar collectors PV/T for modules with and without using a front glass cover. A numerical model of thermal behaviour was carried out for glazed (PV/Tg ) and unglazed (PV/Tun) modules. As a result of this experimental investigation conducted for presented PV/T modules, a sufficient decrease in the cell temperature of PV/Tun compared to the PV/Tg, PV/Tun module exceeded the PV/Tg by 19%. Thus, the electrical productivity of the PV/Tun module was higher; it was 3.44% higher than the PV/Tg value. The outlet liquid temperature of the un-covered module was 6.34% higher than the outlet liquid temperature of the glass-covered module. Besides, the total efficiency of the PV/Tg was higher during the periods of study. In this sense, the glass-covered module is preferable for applications that deal with overall efficiency as a desirable factor. The un-covered module is much beneficial for applications that need high electrical productivity.

Tuning the Mechanical Properties of 3D-Printed Objects by Mixing Chain Transfer Agents in Norrish Type I Photoinitiated RAFT Polymerization.

Photoinduced 3D printing via photocontrolled reversible-deactivation radical polymerization (photoRDRP) techniques has emerged as a robust technique for creating polymeric materials. However, methods for precisely adjusting the mechanical properties of these materials remain limited. In this study, we present a facile approach for adjusting the mechanical properties of 3D-printed objects by adjusting the polymer dispersity within a Norrish type I photoinitiated reversible addition-fragmentation chain transfer (NTI-RAFT) polymerization-based 3D printing process. We investigated the effects of varying the concentrations and molar ratios of trithiocarbonate (BTPA) and xanthate (EXEP) on the mechanical properties of the printed materials. Our findings demonstrate that increased concentrations of RAFT agents or higher proportions of the more active BTPA lead to a decrease in Young's modulus and glass transition temperatures, along with an increase in elongation at break, which can be attributed to the enhanced homogeneity of the polymer network. Using a commercial LCD printer, the NTI-RAFT-based 3D printing system effectively produced materials with tailored mechanical properties, highlighting its potential for practical applications.

Computational study of pulse current and thermal stress on thermoelectric cooler

The thermal performance of a Peltier thermoelectric cooler (TEC) can be enhanced by multi-staging, modifying the geometry of the thermoelement, and using new material with improved thermoelectric properties. This study utilizes COMSOL multiphysics to simulate thermomechanical analyses of various geometries of thermoelectric coolers under pulse current conditions. This investigation explores the influence of pulse current parameters, such as pulse width, pulse ratio, and hot-side convective heat transfer coefficient, on a thermoelectric cooler with different leg geometries. Additionally, the impact of the TEC cold-side temperature, hot-side temperature, and thermal stress on both sides is discussed. The results indicate that TEC leg shapes, such as pin and trapezoid, exhibit the minimum cold-side temperature. Increasing the pulse ratio leads to a decrease in the cold-side temperature and an increase in the hot-side temperature. A notable improvement in the cold-side temperature is also observed with higher pulse ratios, with the pin geometry achieving a minimum cold-side temperature of 276 K. Furthermore, the cooling load affects the temperature on both sides of the TEC. These findings provide valuable insights for optimizing thermoelectric coolers for electronic cooling applications using pulse current methods.

Low temperature tensile behavior and microstructure analysis of copper containing antibacterial stainless steel

Using Shimadzu AGS-100KN universal tensile testing machine, tensile tests were conducted on copper containing antibacterial stainless steel at 25 °C, −20 °C, −60 °C, −100 °C, and −140 °C. The fracture morphology and microstructure evolution of the material were then analyzed using various techniques including scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The experimental findings showed that with the decrease of deformation temperature, the ultimate tensile strength(UTS) increased by about 49.7 %, the yield strength (YS) increased by about 35.5 %, and the elongation(EI) decreased by about 27.3 %, showed obvious low temperature strengthening effect. The High-angle grain boundaries (HAGBs) increased with decreasing temperature, while low-angle grain boundaries (LAGBs) decreased. The plasticity gradually decreased and the strength gradually increased, resulting in an increase in its ability to resist deformation. The number of precipitated phases gradually increased, and the size also gradually becomes larger, and the interaction between the diffusely distributed precipitated phases and dislocations led to precipitation strengthening. With the decrease of temperature, the stacking fault energy gradually decreased, the SFE was 21.26 mJ/m2 at the temperature of −140 °C. The main plastic deformation mechanism of copper-containing austenitic stainless steel in the low-temperature tensile process was transformed from deformation twins to strain-induced martensitic phase transformation.

Adapting Harvests: A Comprehensive Study of Farmers’ Perceptions, Adaptation Strategies, and Climatic Trends in Dera Ghazi Khan, Pakistan

Understanding farmers’ perceptions, attitudes, and adaptation strategies toward climate change is important for developing effective policies that support agricultural development and food security in rural communities. This study aimed to understand climatic trends over the past two decades (2003–2022), farmers’ perceptions, and adaptation strategies regarding climate change in Dera Ghazi Khan, Pakistan. The Mann–Kendall trend test identified a significant decrease in average minimum temperature (τ = −0.357, p < 0.05) and an increase in rainfall patterns (τ = 0.337, p < 0.05). A mixed-method approach is employed, utilizing a survey of 180 randomly selected farmers, focus group discussions, and climate data analysis. Ordinal and binary logistic regression models were used to analyze the influence of sociodemographic factors on farmers’ perceptions of climate change and their choice of adaptation strategies. The results indicate that farmers primarily rely on religious beliefs/prayers (65.6%) to cope with climate change, followed by seeking off-farm jobs (50%) and changing fertilizer use (42.2%). The result of the binary logistic regression indicates that among the different demographic characteristics, education, and land size significantly influence farmers’ decisions in taking adaptation measures against climate change. This study emphasizes the need for climate policies that integrate farmer knowledge with meteorological data and sociodemographic analysis to ensure a sustainable agricultural sector in Pakistan. Further research is necessary to explore more effective adaptation methods.

Influence of cooling bed temperature on microstructural, mechanical properties and surface quality of high-strength seismic-resistant rebar

High-strength seismic-resistant rebar is essential in construction engineering, yet balancing its strength, plasticity, seismic resistance, and surface quality poses challenges. This research explores niobium-vanadium-nitrogen composite reinforced steel, examining how cooling bed temperature affects its microstructure, mechanical properties, and surface quality using advanced microscopy techniques. The research reveals that the steel's microstructure primarily consists of ferrite and pearlite. As cooling bed temperatures decrease, both the proportion and colony size of pearlite, along with ferrite size, show a declining trend. Specifically, reducing the cooling bed temperature from 1100 °C to 900 °C results in a decrease in yield strength, tensile strength, and tensile-to-yield strength ratio by 6 MPa, 27 MPa, and 0.03, respectively. Meanwhile, elongation after fracture, total elongation at maximum force, and strength-ductility balance improve by 3.8%, 1.5%, and 1.93%, respectively. At a cooling bed temperature of 1100 °C, significant blistering occurs on the steel surface. Significant blistering at 1100 °C vanishes at 1000 °C and 900 °C, with diminished silicon enrichment in the surface oxide scale. A cooling bed temperature of 1000 °C ± 20 °C is recommended for optimal performance. This study provides a temperature control strategy for the properties of high-strength seismic-resistant rebar rated at 650 MPa and above, contributing valuable insights to the field of advanced construction materials.