Search Results (8,690)

Given that large-scale storage and transportation of liquid hydrogen are key to realizing the hydrogen economy, tank containers have attracted much attention for their flexibility. To minimize evaporation losses, efficient support structures are essential for these liquid hydrogen tank containers. Herein, a carbon fiber-reinforced polymer (CFRP) suspension ring is developed to support the inner vessel of liquid hydrogen tank containers. By using a special resin matrix and optimizing its curing process, the suspension ring capitalizes on a small cross-sectional area and low thermal conductivity, thereby significantly mitigating the cold-bridge heat transferred from the outer vessel to the inner vessel. Experimental results demonstrate that the tensile strength, outgassing rate, and fatigue performance of the suspension ring at both 77 K (liquid nitrogen temperature) and 4 K (liquid helium temperature) can meet the design targets. Notably, its equivalent thermal conductivity was approximately 88% lower than that of a stainless steel structure of the same size. With the integration of this suspension ring into a 40 ft liquid hydrogen tank container, the daily liquid nitrogen evaporation rate was recorded below 0.082%/d. Furthermore, the holding time before the pressure reached 0.14 MPa exceeded 192 h with a 90% liquid hydrogen filling ratio. This work provides key technical support for high thermal insulation, long-endurance liquid hydrogen storage and transportation equipment. Full article

Fresh paddy transported by barge in the Mekong Delta can accumulate respiration heat during journeys longer than 24 h, accelerating quality deterioration. This study evaluated forced aeration using a 1 m² × 2.5 m laboratory model (approximately 1.4 t) and a field trial on a 60 t barge with aerated and non-aerated compartments. Fresh paddy (24.1 ± 1.4% wet basis) was aerated at an average superficial air velocity of 0.053 m s⁻¹, equivalent to 129 m³ h⁻¹ t⁻¹. Grain temperature, moisture content, airflow, static pressure, air enthalpy, and milling quality were measured. In field trials, aeration reduced grain temperature to approximately 29.0 °C after 6 h, close to ambient temperature (29.3 °C), whereas non-aerated paddy reached 37.8 °C. The temperature difference of approximately 10–11 °C was maintained during transportation. Mean specific heat removal was 616 kJ h⁻¹ t⁻¹, and cumulative thermal exposure decreased from 243.8 to 13.1 °C·h, corresponding to 94.6% suppression. Moisture content and all measured quality indicators did not differ significantly; chalkiness showed a numerical decrease from 7% to 4% (p = 0.101). Forced aeration can therefore stabilize high-moisture paddy during barge transportation and reduce heat-related quality loss. Full article

Black alder (Alnus glutinosa (L.) Gaertn.) wood is characterized by rapid and frequently non-uniform color changes after felling and during hydrothermal processing. These changes are largely associated with extractive compounds, among which oregonin, a phenolic diarylheptanoid glycoside, has been identified as a precursor of the characteristic orange-red coloration. However, information on the thermal stability of oregonin remains limited. This study investigated the effect of temperature and exposure time on oregonin content in black alder bark extract. Aliquots of the extract were exposed to isothermal conditions of 30, 40, 50, and 60 °C for up to 24 h. In a separate trial, a treatment at 98 °C was conducted to simulate the temperature conditions associated with wood saturated water steaming at atmospheric pressure. Oregonin concentration was determined using reversed-phase high-performance liquid chromatography with diode-array detection. Oregonin content remained comparatively stable during 24 h exposure at 30, 40, 50 and 60 °C, with reductions of 6.00%, 3.00%, 2.78%, and 1.64%, respectively, without clear increase in oregonin loss with increasing temperature. Exposure to 98 °C resulted in the most pronounced decrease in oregonin content, with a reduction of 43.93%. The results indicate comparatively high stability of oregonin during 24 h exposure at 30–60 °C, whereas a pronounced decrease was observed in the separate aqueous treatment at 98 °C. These findings are relevant for understanding chemical changes in alder extractives during wood drying and steaming and demonstrate the importance of minimizing unnecessary heat exposure during sample preparation, extraction, and storage. Full article

This study investigates the influence of near-surface air temperature on the performance of internal combustion engines during mobile transects conducted in Mexicali, Baja California, Mexico, one of the hottest cities in North America. Field measurements were carried out along a 15 km urban transect on representative days in April, August, and February. Air temperature and relative humidity were recorded simultaneously at two engine air intake heights (0.66 m and 2.5 m), complemented by surface temperature data obtained from both in situ measurements and Landsat 8 thermal imagery. The results indicate that near-surface air temperature exhibits considerable spatial and temporal variability and is closely associated with land surface temperature (LST) patterns derived from satellite observations. The correction factor (Cf), used to quantify the combined effects of air temperature and atmospheric pressure on engine performance, showed that extremely high temperatures (approaching 50 °C) may reduce engine performance by up to 3.35% relative to standard test conditions. Conversely, cooler winter conditions may improve engine performance by approximately 4.6%. These results suggest that vehicle operation under extremely hot climatic conditions may deviate from the standardized assumptions adopted by the Intergovernmental Panel on Climate Change (IPCC) for emission factor estimation. This study contributes to a better understanding of the effects of extreme urban heat on vehicle performance and demonstrates that localized thermal conditions may influence the assumptions commonly used in vehicle emission assessments. The findings provide valuable information for improving greenhouse gas emission inventories and support evidence-based climate adaptation and urban planning strategies in arid cities. Full article

Mineral-scale deposition remains a persistent flow-assurance and asset-integrity constraint in oil and gas production. Calcium carbonate, calcium sulfate, barium sulfate, iron sulfide, and mixed inorganic scale deposits reduce tubing internal diameter. They also impair near-wellbore permeability, block safety-critical valves, reduce heat-transfer efficiency, and intensify under-deposit corrosion. Conventional management relies on prediction, chemical inhibition, squeeze treatments, acid dissolution, chelation, mechanical scraping, milling, jetting, and operational water management. These methods are indispensable, but each has a restricted operating envelope. Key limitations include mineral selectivity, corrosion risk, environmental discharge, intervention cost, debris generation, and poor effectiveness against chemically resistant sulfate scales, particularly BaSO₄. Ultrasound has therefore attracted interest as a non-chemical technology. Acoustic cavitation, microstreaming, pressure oscillation, mechanical vibration, and micro jetting may suppress nucleation, disturb boundary layers, weaken adhesion, and fragment brittle deposits. This review critically evaluates ultrasound-assisted scale prevention and removal, with emphasis on production tubing and oilfield relevance. Existing studies show credible mechanistic plausibility and promising laboratory performance for CaCO₃, CaSO₄/gypsum, KCl, NaCl, and membrane or heat-transfer fouling systems. It also compares performance metrics, field cases, and technology-readiness barriers. The evidence is less mature for long steel tubulars operating under high-pressure, high-temperature, multiphase production conditions. Current evidence positions ultrasound at technology-readiness level (TRL) 3–4 for CaCO₃ and CaSO₄ systems, where laboratory and bench-scale validation is established, and at TRL 2–3 for BaSO₄, where mechanistic plausibility exists but controlled experimental validation remains absent. The technology is not yet at the pilot–production transition for downhole tubing applications, but it is approaching that threshold for surface process equipment. Its most credible near-term role is as an intensifier paired with low-dose chemical inhibitors, where acoustic boundary-layer disruption can reduce the minimum inhibitory concentration threshold of inhibitors, and with mild chelating agents for early-stage BaSO₄ management, where ultrasound-enhanced mass transfer may accelerate chelant penetration into deposit microstructure. Advancing ultrasound from its current TRL toward field qualification requires targeted BaSO₄ scale validation in steel tubing systems, acoustic field mapping under HPHT multiphase conditions, mass-removal metrics, and a structured pilot programme. Full article

The results of the experiments on the transport process of fluid flow through a pipeline under temperature gradient conditions between the internal and external environments, and on continuous gas generation at the contact boundary of the transported media, are presented in this paper. The test results showed that under non-isothermal flow conditions, a slippage effect will impact flow velocity and pressure, as well as the temperature distributions in variable cross-section pipes. Laboratory experiments were conducted in order to study the effects of the gas nucleus at the pipe walls on the hydrodynamic characteristics of the fluid flow. It is shown that the throughput capacity of the pipe is affected by the temperature difference between the oil and the pipe walls. The test results also demonstrated that at certain temperature gradients on the border layer, the pipe’s capacity reaches its maximum value. Quantitatively, the hydroconductivity of Q/ΔP increased from about 1.45 × 10⁻⁵ m³/(s·MPa) under relatively isothermal conditions to a maximum value of approximately 2.04 × 10⁻⁵ m³/(s·MPa) with a temperature difference in the oil–pipe-wall zone of about 3–5 K, which corresponds to an increase of about 41%. With a further increase in the temperature difference, the hydroconductivity decreased to about 1.64 × 10⁻⁵ m³/(s·MPa) at 10 K and then stabilized in the range of (1.60–1.64) × 10⁻⁵ m³/(s·MPa). This non-monotonic behavior is explained by the temperature-induced release of gas and the formation of a gas-saturated wall zone, which initially reduces the effective resistance of the wall and creates an apparent sliding effect. At high temperature differences, gas accumulation, thermal insulation of the wall area and two-phase flow disturbances limit this effect, which leads to the decrease and subsequent stabilization of the pipe capacity. Full article

High-speed turbulent boundary layers govern the transport of momentum, mass, and energy in compressible flows and play a central role in determining aerodynamic performance, skin-friction drag, aerodynamic heating, flow stability, and thermal protection requirements of advanced aerospace vehicles. Over the past three decades, direct numerical simulation (DNS) has revolutionized the study of compressible wall-bounded turbulence by resolving all dynamically relevant turbulent scales without turbulence-model assumptions, providing benchmark-quality databases and unprecedented physical insight into flow phenomena that remain difficult or impossible to measure experimentally. Together with complementary high-fidelity approaches, DNS has substantially advanced the understanding of turbulence dynamics across a broad range of supersonic and hypersonic flow conditions. This review presents a critical assessment of advances in the high-fidelity simulation of compressible turbulent boundary layers under non-reacting conditions. Particular emphasis is placed on the flow physics of canonical zero-pressure-gradient boundary layers, shock-wave/turbulent-boundary-layer interactions (SWTBLIs), pressure-gradient-driven flows, streamline-curvature effects, and thermochemical non-equilibrium phenomena. Recent developments in numerical methodologies are also briefly examined, including high-order discretization techniques, turbulence inflow generation methods, hybrid continuum-kinetic formulations, and advances in high-performance computing that have enabled DNS at increasingly high Reynolds and Mach numbers. The review highlights the major physical insights emerging from DNS studies, demonstrating that many fundamental characteristics of compressible wall turbulence remain closely related to their incompressible counterparts when appropriate compressibility transformations are employed. At the same time, DNS has revealed the critical influence of wall temperature, pressure gradients, streamline curvature, shock interactions, and finite-rate thermochemistry on turbulence structure, coherent motions, interscale energy transfer, boundary-layer separation, and aerodynamic heating. Full article

This study presents a systematic mapping of methanol spray autoignition, lift-off, and flame development across an engine-relevant range of ambient temperatures (1000–1200 K), injection pressures (70–130 MPa), and O₂ concentrations (21–15 vol.%), using a single fixed injector and optical configuration. In addition, the study reports a dual-fuel strategy to address the low-temperature instability challenges highlighted by the mapping. Within this dataset, ignition delay increases with a lower ambient temperature, reduced injection pressure, or a lower O₂ concentration, while the lift-off length increases with a lower temperature and higher injection pressure. Schlieren imaging consistently captures ignition in the mid-axial region of the jet, softening of spray-head gradients before high-temperature ignition, and occasional upstream ignition sites during the diffusion-controlled phase that affect the flame base position. At the lowest tested temperature of 1000 K, methanol autoignites over a wide ignition-delay range (±1.33 ms), with combustion occurring outside the chamber’s field of view. The corresponding heat-release profile cannot be interpreted conclusively under the current test configuration. Introducing a pilot jet at this condition enables methanol to ignite shortly after the start of injection over a much narrower range (∼±0.10 ms). The resulting combustion event remains within the field of view and occurs much closer to the nozzle compared with its autoignition counterpart. Full article

This study systematically investigates the dynamic mechanical behavior and constitutive modeling of low-temperature quenched and tempered 42CrMo steel under high-strain-rate and high-temperature conditions. Dynamic compression tests were performed using a split Hopkinson pressure bar (SHPB) system over a strain rate range of 460–6450 s⁻¹ and a temperature range of 25–800 °C. The results show that the flow stress of quenched 42CrMo steel exhibits significant strain hardening and temperature softening effects, while its strain rate sensitivity is observed to be relatively low, especially under ultra-high-strain-rate conditions. Based on the experimental data, both the Power-Law and Johnson–Cook constitutive models were established. A hardness-based temperature softening coefficient was introduced to convert the experimental stress–strain curves into isothermal stress–strain curves, thereby effectively decoupling the coupled effects of strain rate and temperature. Error analysis indicates that the Power-Law model yields an average fitting error of 1.98%, which is superior to that of the Johnson–Cook model (3.23%), suggesting that the Power-Law model is more suitable for describing the dynamic mechanical behavior of low-temperature quenched and tempered 42CrMo steel. The findings of this study provide a reliable constitutive basis for numerical simulations of low-temperature quenched and tempered 42CrMo steel under extreme thermomechanical coupling conditions, such as high-speed cutting and impact forming. Full article

Wound management continues to represent a major global healthcare challenge, with the wound care market growing each year and a rising incidence of chronic wounds worldwide. Effective wound healing requires dressings that protect injured tissue, prevent infection, and actively modulate the wound microenvironment to promote tissue regeneration. In recent years, smart polymeric wound dressings have emerged as a functional, more advanced class of wound dressings, engineered from materials capable of responding to stimuli. Physically responsive systems include moisture-adaptive dressings that prevent wound dryness or maceration, pressure-sensitive dressings incorporating flexible capacitive sensors for high mechanical stress mapping, thermoresponsive dressings exploiting sol–gel transitions for temperature-controlled drug release, light-responsive dressings enabling photothermal and photodynamic therapy, and electro-responsive dressings integrating conductive polymers for self-powered electrical stimulation or closed-loop wound monitoring. Chemically responsive systems exploit endogenous biochemical signals, including pH shifts for wound monitoring, reactive oxygen species-cleavable bonds for on-demand drug release, and glucose-responsive platforms for autonomous glycemic regulation in diabetic wounds. Biologically responsive dressings use enzymatic triggers, such as matrix metalloproteinases, hyaluronidase, and bacterial proteases, to achieve autonomous drug delivery. Film-forming sprays further expand the versatility of smart polymeric dressings by enabling contactless application adaptable to irregular wound shapes. In this review, we summarize recent advances in the design, stimuli-responsive mechanisms, characterization methods, and therapeutic outcomes of smart polymeric dressings for wound treatment. Despite promising preclinical results, challenges related to clinical translation, regulatory standardization, and scalable production remain and must be addressed to facilitate widespread clinical adoption. Future directions include multi-stimuli responsive platforms, artificial intelligence-guided wound monitoring, bioprinting of specific dressings, and environmentally sustainable biomaterial design. Full article

This work presents a numerical investigation of a direct oil cooling system for Axial Flux Permanent Magnet (AFPM) machines. Building upon the authors’ previous study, which established the fundamental fluid dynamic mechanisms governing oil jet impingement on curved coil surfaces, the present research extends the analysis by performing a systematic parametric optimization of nozzle diameter and axial position. A validated CFD model, benchmarked against experimental data from the literature, is employed to quantify the influence of jet momentum, stagnation pressure, and flow attachment on the resulting thermal performance. Nine configurations are simulated at constant coolant mass flow rate, revealing that the nozzle diameter is the dominant parameter: smaller diameters generate higher jet velocities, stronger stagnation regions, and larger jet-induced forces, leading to significantly enhanced heat transfer coefficients and Nusselt numbers. Nozzle height plays a secondary yet relevant role, as higher positions promote a more coherent jet core and improve impingement quality. Among the nine simulated cases, the configuration with D = 3 mm and L = 14 mm achieves the lowest hotspot temperature and the most efficient energetic behavior within the simulated set, with only a modest increase in pumping power. The results confirm that direct oil impingement is highly sensitive to jet momentum and angle of attack and demonstrate that optimized nozzle design can substantially improve the thermal management of high power density AFPM machines. This extended analysis provides quantitative references for nozzle sizing and placement within the simulated operating conditions with enhanced cooling efficiency. Full article

Hydrothermal synthesis is a bottom-up, liquid-phase synthesis method and a heterogeneous reaction, utilizing a water solvent at a temperature of >25 °C and a pressure of ≥1 atm to dissolve and to precipitate crystalline or amorphous materials or to get solutions by using a reflux, autoclave, or flow reactor. Microwave-assisted hydrothermal and supercritical flow reactors successfully reduced the synthesis times from hours or days to minutes and seconds. Substitutions for precursors, reductors, or stabilizer chemicals with plant extracts successfully created greener hydrothermal methods, but they still need relatively long times (hours) and high temperatures (>100 °C). The stronger critical perseptives include the inhibited standarization and reproducibility due to plant species variant, plant growth conditions, and plant extraction methods. The plant extract can’t substitute surfactant as mesoporous template or the organic solvents for water-organic sol-vent mixture, and it is possibly photodegraded by microwave. Strategies to reduce time and temperature by mechanical hydrothermal synthesis using plant extracts, with safety prioritized, utilizing non-toxic products, degradable products, and non-harmful reactants, are suggested for future research. One mechanistic question is still not resolved: how distiguish crystalization mechanism by using the temperature reduction method and by using temperature different method. Full article

Ultra-high-temperature ceramic (UHTC) coatings offer a promising route to extending cutting tool service life under severe conditions. This work evaluates the tribological behaviour and wear regime transitions of ZrB₂–SiC/ZrO₂ coatings, deposited by physical vapour deposition (PVD) onto ASSAB-17 high-speed steel tool bits, during dry turning of Ti-6Al-4V. Structural, microstructural, mechanical, and tribological characterisation was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), nanoindentation, and pin-on-disc testing under three pressure–velocity (PV) severity levels, with worn surfaces analysed by SEM and profilometry. The coating exhibited a nanostructured ZrB₂/β-SiC/t-ZrO₂ architecture with a hardness (H) of 24 ± 3 GPa, a hardness-to-reduced-elastic-modulus ratio (H/Er) of 0.100, and an elastic resistance to plastic deformation (H³/Er²) of 0.240 GPa. Three tribological regimes were identified: running-in, steady-state sliding, and progressive degradation, with the highest severity (PV = 6.0 N·m/s) triggering degradation beyond approximately 620 m, a more than one-order-of-magnitude rise in wear rate, and the only case exceeding the tool-life criterion of maximum flank wear (VBmax = 0.30 mm) according to ISO 3685. The main advantage of the proposed approach is that it condenses tool-life-relevant behaviour into a single, easily measurable severity parameter, the PV product, directly applicable to coating design and the selection of safe machining-condition windows. The overall behaviour is consistent with a mechanism governed by the stability and regeneration capacity of a protective tribofilm. As the composition of this layer was not directly characterised, this mechanism is proposed as a phenomenological interpretation, from which a PV threshold is derived as a design criterion for UHTC coatings. Full article

Mortality in smallholder cattle and buffalo systems is climate-driven, but the signal is not uniform: heat and cold stress, flooding, and climate-sensitive disease act through different pathways, yet livestock loss models usually compress them into one elevated-mortality state. The paper builds a climate-state-dependent mortality model for the Thai national herd, separating an endemic baseline from a temperature-extreme and a moisture- and disease-driven regime. A 100,000-iteration Monte Carlo model, calibrated to the 2024 herd and a 2017 farmer survey at 2026 prices, generates the annual loss distribution and decomposes it by driver. The study is a calibrated scenario analysis, not an empirical estimation, so every result is conditional on the calibration and bounded by sensitivity analysis. Endemic mortality governs the average year, about 81% of expected loss but none of the extreme tail; the tail belongs entirely to the two climate regimes, with the moisture- and disease-driven regime carrying roughly 69% of losses beyond the 95th percentile and the temperature regime about 31%. This split holds across low-, medium-, and high-severity scenarios and a baseline range from 0.07 to 0.12, so it is structural: the driver of the typical year is not the driver of the catastrophe. Under a reduced-form behavioral layer with an assumed destocking response, generous payouts would raise stocking pressure 10% to 16% above a sustainable carrying capacity benchmark, so an adaptation instrument could degrade the rangeland it protects. The findings argue for regime-specific risk financing, for pairing insurance with heat and animal health adaptation, and for treating the carrying capacity externality as a design parameter. Full article

Climate risk is increasingly reshaping firms’ operating environments, yet limited evidence exists on how climate-related pressures influence corporate green innovation and through which organizational mechanisms such effects occur. Drawing on induced technological change theory and dynamic capability theory, this study investigates how climate risk, reflected in firms’ exposure to extreme high-temperature days, affects green innovation among Chinese A-share listed manufacturing firms during 2010–2022. The results indicate that climate-related heat shocks significantly promote firms’ green innovation. Mechanism analyses show that this effect operates through two channels: increased R&D investment and enhanced adaptive capacity. Further analyses reveal that the innovation-promoting effect of climate-related pressures is strengthened by regional green finance development but weakened by firms’ financial slack. In addition, the positive effect is concentrated among non-state-owned enterprises and non-heavily polluting firms. This study contributes to the literature by extending induced technological change theory to the firm level and highlighting how climate-related pressures influence green innovation through both resource reallocation and organizational adaptation. The findings also provide new evidence on the roles of external financial support and internal resource conditions in shaping firms’ innovation responses to environmental change. Full article