Search Results (15,386)

Type IV gas cylinders are widely used in the field of vehicles due to their advantages such as light weight, cleanliness, and low cost. Ramie fiber/degradable epoxy resin composites (RFRDE) provide new ideas for the material selection of Type IV gas cylinders due to their advantages of low carbon emissions, low environmental pollution, and renewable resource utilization. However, the poor interfacial bonding strength and moisture resistance between polyethylene plastics and RFRDE have limited their application areas. This study tested the mechanical properties of ramie fibers at different heat treatment temperatures, and studied the thermal mechanical properties of RFRDE through differential scanning calorimeter and curing kinetics methods. At 180 °C, the tensile strength of fiber bundles decreased by 34% compared to untreated fibers. As the highest curing temperature decreases, the tensile strength of RFRDE increases but the curing degree decreases. At the highest curing temperature of 100 °C, the tensile strength of RFRDE is 296 MPa. The effect of the corona discharge and flexible adhesive on the surface modification of polyethylene was analyzed using scanning electron microscopy. These results provide guidance for the development of natural fiber/degradable epoxy resin composite materials. Full article

The quanta-to-energy ratio plays a crucial role in converting energy units to quantum units in the context of photosynthetically active radiation (PAR). Despite its widespread use, the effects of atmospheric particles and solar zenith angle (SZA) on the quanta-to-energy ratio remain unclear. In this study, both simulation and observation data revealed that the principal wavelength, which can be transformed into the quanta-to-energy ratio using a constant, exhibits a slow initial growth, followed by a rapid increase beyond 60° solar zenith angles and a subsequent dramatic decrease after reaching its maximum value. The measured quanta-to-energy ratio demonstrates a variable range of less than 3% for SZA under 70° in a cloudless atmosphere, with significant changes only occurring at zenith angles above 80°. Simulation data indicate that ozone, wind speed, surface-level pressure, surface air temperature, and relative humidity have negligible effects on the quanta-to-energy ratio. The Ångstrom exponent exerts a minor influence on the quanta-to-energy ratio by affecting diffuse radiation. Visibility, however, is found to have a substantial impact on the quanta-to-energy ratio. As a result, two relationships are established, linking the principal wavelength to visibility and the diffuse fraction of PAR. The principal wavelength serves as an effective measure of solar spectrum variability, remaining unaffected by radiation energy. This implies that atmospheric parameters which do not alter the solar spectrum will not influence the principal wavelength. The strong correlations between the principal wavelength, visibility, and the diffuse fraction of PAR suggest a broader range of applications for the principal wavelength in various research domains, opening up new avenues for exploration and potential contributions to numerous fields. Full article

The artificial solar saltworks fields of Hon Khoi are important industrial and biodiversity resources in southern Vietnam. Most hypersaline environments in this area are characterized by saturated salinity, nearly neutral pH, intense ultraviolet radiation, elevated temperatures and fast desiccation processes. However, the extremely halophilic prokaryotic communities associated with these stressful environments remain uninvestigated. To fill this gap, a metabarcoding approach was conducted to characterize these communities by comparing them with solar salterns in northern Vietnam as well as with the Italian salterns of Motya and Trapani. Sequencing analyses revealed that the multiple reuses of crystallization ponds apparently create significant perturbations and structural instability in prokaryotic consortia. However, some interesting features were noticed when we examined the diversity of ultra-small prokaryotes belonging to Patescibacteria and DPANN Archaea. Surprisingly, we found at least five deeply branched clades, two from Patescibacteria and three from DPANN Archaea, which seem to be quite specific to the Hon Khoi saltworks field ecosystem and can be considered as a part of biogeographical connotation. Further studies are needed to characterize these uncultivated taxa, to isolate and cultivate them, which will allow us to elucidate their ecological role in these hypersaline habitats and to explore their biotechnological and biomedical potential. Full article

A phase-field crack model is developed for numerical analysis of thermal buckling and postbuckling behavior of a functionally graded (FG) graphene platelet-reinforced composite (FG-GPLRC) plate with a central crack. The inclined central crack is represented according to a stable, effective phase-field formulation (PFF) by introducing a virtual crack rotation. The problem is formulated using first-order shear deformation theory (SDT) incorporated with von Kármán geometric nonlinearity. And it is approximated by combining regular Laplace interpolation functions and crack-tip singular functions in the framework of the 2D extended natural element method (XNEM). Troublesome shear locking is suppressed by applying the concept of the MITC (mixed-interpolated tensorial components)3+ shell element to the present numerical method. The results demonstrate the effectiveness of this method in accurately predicting the critical buckling temperature rise (CBTR) and the thermal postbuckling path. In addition, the parametric results reveal that the CBTR and postbuckling path of the FG-GPLRC plate are distinct from those of the FG carbon nanotube-reinforced composite (FG-CNTRC) plate and remarkably affected by the parameters associated with the crack and graphene platelet (GPL). Full article

Road greening markedly impacts road thermal comfort and air quality. However, previous studies have primarily focused on thermal comfort or PM_2.5 individually, with relatively few addressing both aspects comprehensively, particularly in humid regions. This study combined field measurements and simulations. It employed physiological equivalent temperature (PET) and quantified the horizontal distribution of particulate matter 2.5 (PM_2.5). The research examines the effects of planting spacing, tree species, and tree–shrub combinations on pedestrian walkways in humid climates during both summer and winter. Using measured tree data and road PM_2.5, a plant model was established and pollution emission parameters were set to validate the effectiveness of the ENVI-met through fitting simulations under various scenarios. The results indicated that (1) plant spacing for trees influenced both the road thermal environment and PM_2.5 levels. Smaller spacing improved thermal conditions but increased PM_2.5. (2) trees with large canopies and high leaf area indices (LAIs) notably enhanced thermal comfort, while those with smaller canopies and dense understories facilitated PM_2.5 dispersion. The 3 m spacing resulted in a maximum absolute PM_2.5 concentration difference (C) of 5.05 μg/m³ in summer and a maximum mean absolute PM_2.5 concentration difference (M) in the downwind region of 2.13 μg/m³ in winter. (3) Combining trees with shrubs moderately improved pedestrian thermal comfort. However, taller shrubs elevated PM_2.5 concentrations on walkways; heights ranging from 1.5 m to 2 m in summer showed higher C values of 5.38 μg/m³ and 5.37 μg/m³. This study provides references and new perspectives for the optimization of roadway greening design in humid areas in China. Full article

With the help of a microscopic model and Green’s function technique, we studied the multiferroic and phonon properties of the recently reported new multiferroic Pr₂FeAlO₆ (PFAO) compound, which belongs to the double perovskite A₂BB’O₆ family. The magnetization decreases with the increase in temperature and disappears at the ferromagnetic Curie temperature $T_C^{FM}$. The polarization increases with the application of an external magnetic field, indicating strong magnetoelectric coupling and confirming the multiferroic behavior of PFAO. In the curves of dependence of the phonon energy and their damping with respect to temperature, a kink is observed at $T_C^{FM}$. This is due to the strong anharmonic spin–phonon interactions, which play a crucial role below $T_C^{FM}$ and are frequently observed in other double perovskite compounds. Above $T_C^{FM}$, only anharmonic phonon–phonon coupling remains. The phonon mode is controlled by an external magnetic field. Full article

Submicron and nanosized powders have gained significant attention in recent decades due to their broad applicability in various fields. This work focuses on ultrasonic spray pyrolysis, an efficient and flexible method that employs an aerosol process to synthesize titanium-based nanoparticles by transforming titanium oxy-sulfate. Various parameters are monitored to better optimize the process and obtain better results. Taking that into account, the influence of temperature on the transformation of titanium oxy-sulfate was monitored between 700 and 1000 °C. In addition to the temperature, the concentration of the starting solution was also changed, and the flow of hydrogen and argon was studied. The obtained titanium-based powders had spherical morphology with different particle sizes, from nanometer to submicron, depending on the influence of reaction parameters. The control of the oxygen content during synthesis is significant in determining the structure of the final powder. Full article

The Gedeo zone agroforestry systems are the main source of Ethiopia’s coffee beans. However, land-use and suitability analyses are not well documented due to complex topography, heterogeneous agroforestry, and lack of information. This research aimed to map the coffee coverage and identify land suitability for coffee plantations using remote sensing, Geographic Information Systems (GIS), and the Analytical Hierarchy Process (AHP) in the Gedeo zone, Southern Ethiopia. Remote sensing classifiers often confuse agroforestry and plantations like coffee cover with forest cover because of their similar spectral signatures. Mapping shaded coffee in Gedeo agroforestry using optical or multispectral remote sensing is challenging. To address this, the study identified and mapped coffee coverage from Sentinel-1 data with a decibel (dB) value matched to actual coffee coverage. The actual field data were overlaid on Sentinel-1, which was used to extract the raster value. Pre-processing, classification, standardization, and reclassification of thematic layers were performed to find potential areas for coffee plantation. Hierarchy levels of the main criteria were formed based on climatological, edaphological, physiographic, and socioeconomic factors. These criteria were divided into 14 sub-criteria, reclassified based on their impact on coffee growing, with their relative weights derived using AHP. From the total study area of 1356.2 km², the mapped coffee coverage is 583 km². The outcome of the final computed factor weight indicated that average annual temperature and mean annual rainfall are the primary factors, followed by annual mean maximum temperature, elevation, annual mean minimum temperature, soil pH, Land Use/Land Cover (LULC), soil texture, Cation Exchange Capacity (CEC), slope, Soil Organic Matter (SOM), aspect, distance to roads, and distance to water, respectively. The identified coffee plantation potential land suitability reveals unsuitable (413 km²), sub-suitable (596.1 km²), and suitable (347.1 km²) areas. This study provides comprehensive spatial details for Ethiopian cultivators, government officials, and agricultural extension specialists to select optimal coffee farming locations, enhancing food security and economic prosperity. Full article

This paper introduces a new mathematical modelling method of a thermoelastic and electromagnetic half-space in the context of four different thermoelastic theorems: Green–Naghdi type-I, and type-III; Lord–Shulman; and Moore–Gibson–Thompson. The bunding plane of the half-space surface is subjected to ramp-type heat and traction-free. We consider that Maxwell’s time-fractional equations have been under Caputo’s fractional derivative definition, which is the novelty of this work. Laplace transform techniques are utilized to obtain solutions using the state-space approach. Laplace transform’s inversions were calculated using Tzou’s iteration method. The temperature increment, strain, displacement, stress, induced electric field, and induced magnetic field distributions were obtained numerically and are illustrated in figures. The time-fraction parameter of Maxwell’s equations had a major impact on all the studied functions. The time-fractional parameter of Maxwell’s equations worked as resistant to the changing of temperature, particle movement, and induced magnetic field, while it acted as a catalyst to the induced electric field through the material. Moreover, all the studied functions have different values in the context of the four studied theorems. Full article

In order to explore the influence of laser power on the evolution of molten pool and convective heat transfer of laser cladding Incoloy 926 on stainless steel surface, a three-dimensional thermal fluid multi-field coupled laser cladding numerical model was established in this paper. The variation of latent heat during solid-liquid phase transformation was treated by apparent heat capacity method. The change in the gas–liquid interface was tracked using the mesh growth method in real time. The instantaneous evolution of temperature field and velocity flow field of laser cladding Incoloy 926 on a stainless steel surface under different laser power was discussed. The solidification characteristic parameters of the cladding layer were calculated based on the temperature-time variation curves at different nodes. The mechanism of the impact of laser power on the microstructure of the cladding layer was revealed. The experiment of laser cladding Incoloy 926 on 316L surface was carried out under different laser power. Combined with the numerical simulation results, the effects of laser power on the geometrical morphology, microstructure and element distribution of the cladding layer were compared and analyzed. The results show that with the increase in laser power, the peak temperature and flow velocity of the molten pool surface both increase significantly. The thermal influence of the molten pool center on the edge is enhanced. The temperature gradient, solidification rate, and cooling rate increased gradually. The microstructure parameters (G/R) are relatively small when the laser power is 1000 W. In the experimental range, the dilution rate and wetting angle of the cladding layer both increase with the increase in laser power. When the laser power is 1000 W, the alloying elements of the cladding layer are more evenly distributed and the microstructure is finer. The experimental results are in good agreement with the simulation results. Full article

Underground spaces contain abundant geothermal energy, which can be recovered for building ventilation, reducing energy consumption. However, current research lacks a comprehensive quantitative assessment of its energy recovery. This research evaluates the energy recovery potential of the Xingfu Forest Belt Urban Underground Utility Tunnels. Field experiments revealed a 7 °C temperature difference in winter and a 2.5 °C reduction during the summer-to-autumn transition. A computational fluid dynamics (CFD) model was developed to assess the impact of design and operational factors such as air exchange rates on outlet temperatures and heat exchange efficiency. The results indicate that at an air change rate of 0.5 h⁻¹, the tunnel outlet temperature dropped by 10.5 °C. A 200 m tunnel transferred 8.7 × 10¹⁰ J of heat over 30 days, and a 6 m × 6 m cross-sectional area achieved 1.1 × 10¹¹ J of total heat transfer. Increasing the air exchange rate and cross-sectional area reduces the inlet–outlet temperature difference while enhancing heat transfer capacity. However, the optimal buried depth should not exceed 8 m due to cost and safety considerations. This study demonstrates the potential of shallow geothermal energy as an eco-friendly and efficient solution for enhancing building ventilation systems. Full article

Intumescent fireproof coatings protect steel structures and cables by forming a thick, fire-resistant layer under high temperatures. These coatings can deteriorate over time, impacting their fire resistance. Current testing methods are largely lab-based, lacking in-service evaluation platforms. Laser-Induced Breakdown Spectroscopy (LIBS) is emerging as a promising in situ detection technology but is influenced by low air pressure in high-altitude areas. This study investigates how air pressure affects LIBS signals in intumescent coatings on galvanized steel. Using pressures between 35 and 101 kPa, a linear model was developed to correlate laser pulses to ablation depth for characterizing coating thickness. Results show that spectral intensity decreases with lower air pressure. However, a strong linear relationship persists between laser pulses and ablation depth, with a fitting accuracy above 0.9. The coating thickness is identified by the number of laser pulses required to detect the Zn spectral line from the underlying galvanized steel. As air pressure decreases, the ablation depth increases. The study effectively models and corrects for air pressure effects on LIBS data, enabling its application for field detection of fireproof coatings. This advancement enhances the reliability of LIBS technology in assessing the fire performance of these materials, providing a reference for their in situ evaluation and ensuring better fire safety standards for building steel structures and cables. Full article

Biospecimen imaging is essential across various fields. In particular, a considerable amount of research has focused on developing pretreatment techniques, ranging from freeze-drying to the use of highly conductive polymers, and on advancements in instrumentation, such as cryogenic electron microscopy. These specialized techniques and equipment have facilitated nanoscale and microscale bioimaging. However, user access to these environments remains limited. This study introduced a novel technique to achieve high conductivity in bioimaging by employing a magnetically controlled sputtering cathode to facilitate low-temperature deposition and low-electron bombardment. This approach allows for the convenient high-magnification observation of highly structured three-dimensional specimens, such as pill bugs and butterfly wings, and fragile specimens, such as single-cell protozoan parasites, using metal deposition only. Furthermore, it is easily accessible in the field of bioimaging because it does not require any pretreatment and enables surface analysis of biospecimens with an electron microscope using only a single pretreatment process. Protozoa, which are microorganisms, were successfully observed at high magnification without structural changes due to thermal denaturation. Furthermore, metallic film deposition and electrochemical signal measurements using these metallic films were achieved in pill bugs. Full article

Effective temperature control measures are crucial for achieving temperature regulation and preventing cracking in the dam body during the construction of large-volume concrete gravity dams. Due to the low ambient temperatures in winter, it is especially important to focus on temperature control measures for concrete dam construction in cold regions. This paper employs a numerical simulation method that takes into account dam temperature control measures to simulate and predict the overall temperature and stress fields of the Guanmenzuizi Reservoir Dam, and validates these simulations with field monitoring results. This study finds that the ambient temperature significantly impacts the temperature and stress of the dam body’s concrete. The internal temperature of the dam reaches its highest value approximately 7 days after pouring, followed by periodic fluctuations, with the dam body’s temperature changes exhibiting a certain lag compared to the ambient temperature. The interior of the dam is under compression, while the upstream and downstream surfaces experience significant tensile stress. This project adopts targeted temperature control measures for the cold environmental conditions of the region, which are reasonably implemented and effectively reduce the temperature rise of the concrete during construction, achieving the temperature control objectives. This study also explores the impact of the cooling water pipe density on the dam body. The research results offer valuable references for the implementation of temperature control measures and the establishment of temperature control standards for concrete gravity dams in cold regions. Full article

In this experimental study, ethanol, an eco-friendly fuel used to reduce harmful exhaust emissions from internal combustion engines, was blended with gasoline. To optimize the combustion and the shape of the combustion chamber, the spray development and spray behavior of ethanol and gasoline were visualized and compared. Droplets of injected fuel were visualized using a high-speed camera. Because it is difficult to experimentally observe fuel vaporization using only high-speed cameras, the vaporization characteristics of the spray were compared and analyzed by using the background-oriented schlieren (BOS) method with density variation and image displacement in the spray flow field to visualize the vaporized fuel. The experimental results indicate that the fuel vaporization phenomenon could be observed during the spray development and that more fuel vaporization occurred at higher ambient temperatures and lower ambient pressures. Additionally, the dependence of the differences in the vaporization characteristics of the fuel and the wall-wetting phenomenon caused by the vaporized fuel was analyzed. Full article