Search Results (65,697)

Feedstock quality has been proven to be the single variable that most affects fluid catalytic cracking (FCC) unit performance, but catalyst characteristics have also been reported in the literature to have a considerable effect on cracking process performance. How these two main variables of the FCC process complement each other in the search for ways to optimize the performance of the FCC unit is the subject of current research. Twenty-one feedstocks with K_W-characterizing factors ranging from 11.08 to 12.06, Conradson carbon contents ranging from 0.05 to 12.8 wt.%, and nitrogen contents ranging from 800 to 3590 ppm (wt/wt) (basic nitrogen from 172 to 1125 ppm (wt/wt)) were cracked on 21 catalysts with micro-activity between 67% and 76% (wt/wt) in a laboratory-based advanced catalytic evaluation (ACE) unit at a reaction temperature of 527ׄ °C, catalyst–to-oil ratios between 3.5 and 12.0 wt/wt, and a catalyst time on stream of 30 s. Some of the feeds and catalysts tested in the laboratory FCC ACE unit were also examined in a commercial short-contact-time FCC unit resembling a UOP side-by-side design. It was found that conversion can be very well predicted in both the laboratory ACE and the commercial FCC units using multiple linear correlations developed in this work from information about the following feed properties: K_W-characterizing factor, nitrogen content, and micro-activity of the catalyst. The coke on the catalyst that controls the catalyst-to-oil ratio and the regenerator temperature in the commercial FCC unit could be calculated using the correlations developed in this work for the laboratory ACE and commercial FCC units, based on feed characteristics and catalyst micro-activity. Due to the greater slope of the Δ coke/Δ micro-activity dependence observed in the ACE FCC unit, the more active catalysts show weaker results compared to the less active catalysts at a constant coke yield. In contrast, catalysts with higher activity are preferable for operation in the commercial FCC plant because they provide higher conversion at the same coke yield due to the lower slope of the Δ coke/Δ micro-activity relationship. Full article

The adaptation strategies of species to local environments are reflected in phenotypic variations, which could be expressed as trait patterns across the community level. Here, we compiled a dataset of small mammal traits to evaluate the classic ecological rules and to assess predictions related to drought resistance. In June 2017, July 2023, and May–June 2024, a field survey was conducted in Baima Snow Mountain, southwest China, using standardized methods to capture small mammals. Traits potentially corresponding to variations in temperature, productivity, and water availability were measured in the field or calculated in the laboratory. We applied ordinary least squares (OLS) linear regressions to determine the community-level trait variations along the gradients of environmental factors influenced by rain-shadow effects of the mountain system. Results showed that (1) body size decreased with increasing temperature, aligning well with conventional prediction; (2) the proportion of appendage size attributable to allometry decreased with temperature but increased slightly with productivity, thereby violating Allen’s rule while being partly consistent with the resource rule; (3) the renal features did not support the expected negative association concerning water availability but its converse, which may be explained by microhabitat conditions and broad-scale zoogeographic influences within the local community. We conclude that community-level phenotypic variations in small mammals result from complex influences, including climate, productivity, habitat characteristics, and adaptive strategies operating at both micro and macro scales. Full article

Effective thermal management is critical for sustaining the performance, durability, and stability of a proton exchange membrane fuel cell (PEMFC). A thorough numerical investigation of six multi-fin zigzag cooling-channel geometries operating under three slope angles (75°, 90°, and 120°) is presented to monitor the combined impact of geometric complexity and channel inclination on cooling performance. In addition, temperature fields, velocity distributions, localized heat flow, total heat removal, and cooling efficiency were reviewed to characterize thermal–fluid behavior of the individual configuration. The results showed that geometric refinement had the strongest influence on cooling performance, with Type 5 (a = 2, b = 4, h = 2) and Type 6 (a = 4, b = 4, h = 2) progressively achieving declining temperature distributions, greater outlet velocities, and modified coolant mixing. Slope angles also affected flow behavior, where reduced inclination extended coolant residence time and elevated inclination intensified secondary flows, although the influence was secondary to geometry. Total heat flow, area-specific heat extraction, and cooling efficiency were highest in Type 5 (a = 2, b = 4, h = 2) and Type 6 (a = 4, b = 4, h = 2), with Type 5 exhibiting an optimal balance between flow disturbance and hydraulic resistance. This study generally presented practical design guidance for next-generation PEMFC cooling systems, proving that optimized multi-fin zigzag channels significantly advanced thermal uniformity and heat-transfer effectiveness under diverse operating conditions. Full article

The research and development of new accident-tolerant fuel cladding materials has emerged as a critical focus in international academic and engineering fields following the Fukushima nuclear accident. Due to the outstanding resistances in corrosion and radiation as well as high-temperature creep properties, oxide dispersion-strengthened (ODS) FeCrAl alloys have been studied extensively during the past decade. Current review articles in this field have primarily focused on the effects of chemical composition on the anti-corrosion performance and species of nano-oxide. However, several key issues have not been given adequate attention, including processing methods and parameters, high-temperature stability mechanisms, post-deformation microstructural evolution and high-temperature mechanical properties. This paper reviews the progress of basic research on ODS FeCrAl alloys, including preparation methods, the effects of preparation parameters, the thermal stability and irradiation stability of oxides, the microstructural deformation, and the mechanical properties at elevated temperatures. The aspects mentioned above not only provide valuable references for understanding the effects of preparation parameters on the microstructure and properties of ODS FeCrAl alloys but also offer a comprehensive framework for the subsequent optimization of ODS FeCrAl alloys for nuclear reactor applications. Full article

This study presents an optical and thermal design for a compact 10× periscope zoom lens suitable for smartphones, employing a hybrid thermal compensation scheme to ensure stable imaging performance over a wide range of temperatures. Our proposed zoom optics system integrates passive and active compensation mechanisms, further enhancing thermal stability through the use of a curved image sensor. Passive compensation is achieved through the selection of low-G optical materials and an optimized structural configuration. In contrast, active compensation dynamically adjusts the zoom group position in response to changes in ambient temperature. Optical simulations confirm that this 10× periscope zoom lens, composed of a prism, eight aspherical lenses, and two parallel plates, maintains diffraction-limited resolution and less than 2% distortion at all zoom positions (Zoom 1 to Zoom 6), achieving a total depth of 4.96 mm. Thermal analysis at temperatures ranging from −20 °C to 60 °C demonstrates that the optimized design, utilizing a curved sensor (Design type 3), achieves an average MTF of 0.58 and an average degradation rate of only 12.8%, exhibiting excellent non-thermal performance. These results highlight the effectiveness of the proposed novel hybrid thermal compensation strategy and surface sensor integration in realizing high-magnification, thermally stable periscope optics for next-generation smartphone imaging systems. Full article

Sewer corrosion driven by sulfur metabolism threatens infrastructure durability. Current study examined the effect of conductive lining materials on microbial communities and sulfide control under simulated sewer conditions. Three lab-scale reactors (3.5 L total volume, 2.1 L working volume) were prepared with amorphous carbon (SAN-EARTH) and magnetite-black (MTB) linings, while a Portland cement reactor with no coating served as the control. Each reactor was operated for 120 days at room temperature and fed with artificial wastewater. The working volume consisted of 1.4 L of synthetic wastewater mixed with 0.7 L of sewage sludge used as the inoculum source. Sulfate, sulfide, hydrogen sulfide, nitrogen species, pH, and organic carbon were monitored, and microbial dynamics were analyzed via 16S rRNA sequencing and functional annotation. SAN-EARTH and MTB reactors completely suppressed sulfide and hydrogen sulfide, while Portland cement showed the highest accumulation. Both conductive linings maintained alkaline conditions (pH 9.0–10.5), favoring sulfide oxidation. Microbial analysis revealed enrichment of sulfur-oxidizing bacteria (Thiobacillus sp.) and electroactive taxa (Geobacter sp.), alongside syntrophic interactions involving Aminobacterium and Jeotgalibaca. These findings indicate that conductive lining materials reshape microbial communities and sulfur metabolism, offering a promising strategy to mitigate sulfide-driven sewer corrosion. Full article

The fabrication of thin-walled plastic parts has potential in the automotive industry in terms of sustainability and circular economy targets to decrease any harmful effects on the ecosystems, cost and performance. Injection molding of thin-walled automotive parts is more complex in terms of processing defects compared to traditional plastic parts. Optimization of processing parameters is of critical importance to solving problems and defects in the production of thin-walled parts. In this study, the flow length and weight of thin-walled spiral parts (with wall thicknesses of 0.50, 1.50, 2.70 and 3.00 mm) were investigated with theoretical and experimental studies. The theoretical flow length and weight of the thin-walled spiral parts were determined by Moldflow analysis according to the pressure and wall thickness. The correlation graph between theoretical results and experimental measurements was obtained. When the wall thickness of the thin-walled spiral parts increased, the flow length of the thin-walled spiral parts increased. As a result, it was found that the thin-walled spiral part mold could not be filled for wall thicknesses of 0.50 and 1.50 mm at maximum pressure due to decreasing temperature at the flow front. In addition, the thin-walled spiral part mold can be filled for a wall thickness of 2.70 and 3.00 mm. In the correlation study conducted for these values, an agreement of approximately 90% was achieved. However, it was also observed that as the pressure increases, the deviation between the experimental and theoretical results becomes more pronounced. Full article

Electromagnetic pumps are developed for industrial, medical and scientific applications, moving electrically conductive liquids and molten solder in electronics manufacturing using electromagnetism instead of mechanical parts. This study presents a comprehensive thermal analysis of an electromagnetic diaphragm pump, focusing on the influence of operating current, permanent magnet switching speed, and cooling conditions on pumping performance. The pump utilizes a flexible diaphragm embedded with a permanent neodymium magnet, which interacts with time-varying magnetic fields generated by electromagnets to drive fluid motion. Temperature monitoring is conducted using a waterproof DS18B20 sensor and an uncooled FLIR A325sc infrared camera, allowing accurate mapping of thermal distribution across the pump surface. Experimental results demonstrate that higher current and increased magnet switching speed lead to faster temperature rise, impacting the volume of fluid pumped. Incorporation of an automatic cooling fan effectively reduces coil temperature and stabilizes pump performance. Polynomial regression models describe the relationship between temperature, pumped liquid volume, and magnet switching speed, providing information to optimize pump operation and cooling strategies. The novel relationship between temperature and the volume of the pumped liquid is considered as a fourth-degree polynomial. In particular the model describes a quantitative evaluation of the effect of heating on pumping efficiency. An initial increase in temperature correlates with a higher pumped volume, but excessive heating leads to efficiency saturation or even decline. Indeed, mathematical dependencies are crucial in mechanical pump engineering for analyzing physical phenomena; this is achieved by using a mathematical equation to define how different physical variables are related to each other, enabling engineers to calculate performance and optimize the pump design. Full article

Utilizing waste tire crumb rubber to modify asphalt enhances the damping and noise reduction performance of pavements. This study employs a multi-scale approach to investigate the effect of crumb rubber content (5–25%) on the damping performance of crumb rubber-modified asphalt (CRMA). The results show that damping performance improves initially with increasing crumb rubber content, peaking at 20%, and then declines. At this optimal content, the loss modulus increases by 110% and 440% at 46 °C and 82 °C, respectively, compared to base asphalt, with enhanced damping efficiency and damping temperature stability. Fluorescence microscopy (FM) images and quantitative analysis reveal that, at 20%, the crumb rubber forms a moderately connected three-dimensional network. Molecular dynamics (MD) simulations indicate that, at this content, the solubility parameter of the CRMA system is closest to that of the base asphalt, and interfacial binding energy increases, suggesting optimal compatibility. Ridge regression models, with R² values of 0.903 and 0.876 for the FM and MD scales, respectively, confirm that crumb rubber dispersion is the dominant factor governing damping performance, with moderate phase separation further enhancing performance. This study establishes a quantitative structure–property relationship, providing a framework for understanding the damping performance of rubber-modified asphalt pavements. Full article

Liquid-fueled molten salt reactors (MSRs) are characterized by the use of liquid nuclear fuel, which leads to a unique thermal-hydraulic phenomenon in the core involving the simultaneous occurrence of nuclear fission heat generation and convective heat transfer. This distinctive behavior creates a critical need for high-fidelity experimental data on internally heated flows, yet such studies are severely constrained by the lack of methods to generate controllable, high-power-density volumetric heat sources in fluids. To address this methodological gap, this study proposes and numerically investigates a novel experimental concept based on microwave heating. The design features an innovative multi-tier hexagonal resonant cavity with fifteen strategically staggered magnetrons. A comprehensive multi-physics model was developed using COMSOL Multiphysics to simulate the coupled electromagnetic, thermal, and fluid flow processes. Simulation results confirm the feasibility of generating a volumetric heat source, achieving an average power density of 6.9 MW/m³. However, the inherent non-uniformity in microwave power deposition was quantitatively characterized, revealing a high coefficient of variation (COV) for power density. Crucially, parametric studies demonstrate that this non-uniformity can be effectively mitigated by optimizing the flow channel geometry. Specifically, using a smaller diameter tube or an annulus pipe significantly improved temperature field uniformity, reducing the temperature COV by over an order of magnitude, albeit at the cost of reduced absorption efficiency. Preliminary discussion also addresses the extension of this approach towards molten salt experiments. The findings establish a practical design framework and provide quantitative guidance for subsequent experimental investigations into the thermal-hydraulic behavior of internally heated fluids, offering a promising pathway to support the design and safety analysis of liquid-fueled MSRs. Full article

The increasing share of renewable energy sources (RES) in modern power systems necessitates the development of efficient, large-scale energy storage technologies capable of mitigating generation variability. Liquid Air Energy Storage (LAES), particularly in its adiabatic form, has emerged as a promising candidate by leveraging thermal energy storage and high-pressure air liquefaction and regasification processes. Although LAES has been widely studied, the impact of ambient temperature on its performance remains insufficiently explored. This study addresses that gap by examining the thermodynamic response of an adiabatic LAES system under varying ambient air temperatures, ranging from 0 °C to 35 °C. A detailed mathematical model was developed and implemented in Aspen Hysys to simulate the system, incorporating dual refrigeration loops (methanol and propane), thermal oil intercooling, and multi-stage compression/expansion. Simulations were conducted for a reference charging power of 42.4 MW at 15 °C. The influence of external temperature was evaluated on key parameters including mass flow rate, unit energy consumption during liquefaction, energy recovery during expansion, and round-trip efficiency. Results indicate that ambient temperature has a marginal effect on overall LAES performance. Round-trip efficiency varied by only ±0.1% across the temperature spectrum, remaining around 58.3%. Mass flow rates and power output varied slightly, with changes in discharging power attributed to temperature-driven improvements in expansion process efficiency. These findings suggest that LAES installations can operate reliably across diverse climate zones with negligible performance loss, reinforcing their suitability for global deployment in grid-scale energy storage applications. Full article

Museums open to the public must reconcile heritage preservation requirements with energy-conscious microclimate management and visitors’ environmental experience. In historic buildings, indoor conditions are typically controlled primarily for preventive conservation, while opportunities for detailed assessment of human comfort are often limited by existing monitoring systems and operational constraints. This study investigates visitors’ perceptions of thermal conditions and indoor air quality (IAQ) in two branches of the National Museum in Krakow (NMK) characterized by different microclimate-control strategies: the mechanically ventilated and air-conditioned Cloth Hall and the predominantly passively controlled Bishop Erazm Ciołek Palace. A pilot survey was conducted in spring 2023 to capture subjective assessments of thermal sensation and perceived IAQ. These perceptions were contextualized using long-term air temperature and relative humidity data (2013–2023) routinely monitored for conservation purposes. Environmental data were analyzed to assess the stability of indoor conditions and to provide background for interpreting survey responses, rather than to perform a normative evaluation of thermal comfort. The results indicate that visitors frequently perceived the indoor environment as slightly warm and reported lower air quality in the Palace, where air was often described as stale or stuffy. These perceptions occurred despite relatively small differences in monitored air temperature and relative humidity between the two buildings. The findings suggest that ventilation strategy, air exchange effectiveness, odor accumulation, room configuration, and lighting conditions may influence perceived environmental quality more strongly than temperature or humidity alone. Although limited in scope, this pilot study highlights the value of incorporating visitor perception into discussions of energy-conscious microclimate management in museums and indicates directions for further multidisciplinary research. Full article

Explosive volcanic eruptions are key drivers of climate variability, yet their hemispheric-dependent impacts remain uncertain. Using multi-model ensembles from Coupled Model Intercomparison Project Phase 6 (CMIP6) historical data and Decadal Climate Prediction Project (DCPP) simulations, this study examines how the spatial distribution of volcanic aerosols modulates climate responses to Northern Hemisphere (NH), Tropical (TR), and Southern Hemisphere (SH) eruptions. The CMIP6 ensemble captures observed temperature and precipitation patterns, providing a robust basis for assessing volcanic effects. The results show that the hemispheric distribution of aerosols strongly controls radiative forcing, surface air temperature, and hydrological responses. TR eruptions cause nearly symmetric cooling and widespread tropical rainfall reduction, while NH and SH eruptions produce asymmetric temperature anomalies and clear Intertropical Convergence Zone (ITCZ) displacements away from the perturbed hemisphere. The vertical temperature structure, characterized by stratospheric warming and tropospheric cooling, further amplifies hemispheric contrasts through enhanced cross-equatorial energy transport and shifts in the Hadley circulation. ENSO-like responses depend on eruption latitude, TR and NH eruptions favor El Niño–like warming through westerly wind anomalies and Bjerknes feedback, and SH eruptions induce La Niña–like cooling. The DCPP experiments confirm that these signals primarily arise from volcanic forcing rather than internal variability. These findings highlight the critical role of aerosol asymmetry and vertical temperature structure in shaping post-eruption climate patterns and advancing the understanding of volcanic–climate interactions. Full article

Rapid human population growth accelerates biodiversity loss through urban habitat fragmentation, yet ecologically informed urban planning can mitigate these effects. This study evaluates whether and how vegetation characteristics, as captured by Earth observation data varies across forest habitats in a small Mediterranean city in Italy. The Normalized Difference Vegetation Index (NDVI), the Normalized Difference Moisture Index (NDMI), and Land Surface Temperature (LST) for the Functional Urban Area of Campobasso were derived from multitemporal Landsat 8 imagery (2020–2023) acquired during the growing season and combined with elevation data to account for topographic gradients. Different forest habitats were identified using the regional coeval Carta della Natura (Map of Nature) and were sampled by a random stratified strategy yielding more than 900,000 observations. A linear mixed-effects model was used to model NDVI as a function of NDMI, LST, elevation, and habitat type, while accounting for temporal and spatial dependencies. The model explained a large proportion of NDVI variability (marginal R² = 0.75; conditional R² = 0.85), with NDMI emerging as the strongest predictor, followed by weaker effects of LST and elevation. Habitat differences were also evident: oak-dominated forests (i.e., Quercus frainetto, Q. cerris, and Q. pubescens dominated habitats) exhibited the highest NDVI values, while coniferous plantations (i.e., Pinus nigra dominated habitat) had the lowest; forests dominated by Robinia pseudoacacia and riparian Salix alba showed intermediate vegetation greenness values. These results highlight the ecological importance of oak forests in Mediterranean urban landscapes and demonstrate the value of satellite-based monitoring for capturing habitat variability. The reproducible workflow applied here provides a scalable tool to support habitat conservation and planning in urban environments, also accounting for impending climate change scenarios. Full article

The artificial ground freezing (AGF) technique is widely used in the construction of subway cross passages due to its advantages of good water sealing, strong adaptability, and minimal environmental impact. However, groundwater seepage adversely affects the formation of the frozen wall. The functional relationship between the content of unfrozen water and the temperature in saturated sandy gravel was obtained using frequency domain reflectometry (FDR). Based on the theories of heat transfer and seepage in porous media, a coupled hydrothermal mathematical model of saturated ground considering phase change was established. This model was verified using results from a model test and a freezing project for a subway cross passage. Building on this, the influence of seepage velocity on the formation and closure time of the frozen wall was studied, and prediction formulas for closure times under different seepage velocities were proposed. The results demonstrate the effectiveness of the VG–Clapeyron model in predicting the unfrozen water content in saturated sandy gravel. Groundwater seepage is the core factor affecting the formation of the frozen wall. As seepage velocity increases, closure times for both the cross passage and the pump room are significantly delayed, and the difference between their respective closure times increases. The upstream sidewall is the weak link in frozen wall expansion under seepage conditions. Monitoring of the temperature field in this area should be strengthened to track the formation of the frozen wall. Full article