Search Results (197)

High-titanium steel contains an elevated titanium content, which promotes the formation of abundant non-metallic inclusions in molten steel at high temperatures, including titanium oxides, sulfides, and nitrides. These inclusions adversely affect continuous casting operations and generate substantial internal/surface defects in cast slabs, ultimately compromising product performance and service reliability. Therefore, stringent control over the size, distribution, and population density of inclusions is imperative during the smelting of high-titanium steel to minimize their detrimental effects. In this paper, samples of high titanium steel (0.4% Ti, 0.004% N) casting billets were analyzed by industrial test sampling and full section comparative analysis of the samples at the center and quarter position. Using the Particle X inclusions, as well as automatic scanning and analyzing equipment, the number, size, location distribution, type and morphology of inclusions in different positions were systematically and comprehensively investigated. The results revealed that the primary inclusions in the steel consisted of TiN, TiS, TiC and their composite forms. TiN inclusions exhibited a size range of 1–5 µm on the slab surface, while larger particles of 2–10 μm were predominantly observed in the interior regions. Large-sized TiN inclusions (5–10 μm) are particularly detrimental, and this problematic type of inclusion predominantly concentrates in the interior regions of the steel slab. A gradual decrease in TiN inclusion number density was identified from the surface toward the core of the slab. Thermodynamic and kinetic calculations incorporating solute segregation effects demonstrated that TiN precipitates primarily in the liquid phase. The computational results showed excellent agreement with experimental data regarding the relationship between TiN size and solidification rate under different cooling conditions, confirming that increased cooling rates lead to reduced TiN particle sizes. Both enhanced cooling rates and reduced titanium content were found to effectively delay TiN precipitation, thereby suppressing the formation of large-sized TiN inclusions in high-titanium steels. Full article

Conventional asphalt is prone to cracking in cold climates due to its poor flexibility and limited ability to regulate temperature. This study investigates the use of low-temperature microencapsulated phase-change materials (MPCMs) to improve both the thermal storage and low-temperature performance of asphalt. MPCMs were incorporated into asphalt through physical blending at various concentrations. The physical, thermal, and rheological properties of the asphalt were then systematically evaluated. Tests included penetration, softening point, ductility, thermogravimetric analysis (TGA), and dynamic shear rheometer (DSR). The addition of MPCMs increased penetration and ductility. It slightly reduced the softening point and viscosity. These changes suggest improved flexibility and workability at low temperatures. Rheological tests showed reductions in rutting and fatigue factors. This indicates better resistance to thermal and mechanical stresses. Bending Beam Rheometer (BBR) results further confirmed that MPCMs lowered creep stiffness and increased the m-value. These findings demonstrate improved crack resistance under cold conditions. Thermal cycling tests also showed that MPCMs delayed the cooling process and reduced temperature fluctuations. This highlights their potential to enhance both energy efficiency and the durability of asphalt pavements in cold regions. Full article

This study presents a novel conceptual model to explain the differential rotation within Earth’s layers, a phenomenon observed through seismic wave studies but not fully understood. While geodynamo theory and electromagnetic coupling models have been proposed to explain this phenomenon, our model offers an alternative perspective focusing on the Moon’s tidal forces. Our model proposes that the Moon’s tidal forces play a crucial role in this process, acting as a braking mechanism on Earth’s rotation. We hypothesize that these tidal forces initially decelerate the Earth’s crust and mantle, with this effect sequentially transmitted to deeper layers. A key aspect of our model is the role of the liquid outer core in mediating this process. We suggest that the liquid state of the outer core delays the transmission of tidal friction, resulting in differential rotation between layers in contact with it. This delay mechanism provides a potential explanation for the observed rotational differences between the mantle and core. Our model demonstrates that about 66,000 years after the Moon’s formation, the tidal force slowed the crust–mantle rotation by approximately 5.5 degrees per year more than the core. Furthermore, we estimate that the frictional heat generated at the boundaries of differential rotation is about 0.3478 TW. At this rate, the outer core temperature would increase by approximately 13.4 K per billion years. This thermal effect may have significant implications for the long-term evolution of Earth’s core, potentially slowing its cooling rate and maintaining its liquid state. Our model thus provides a new perspective on the interplay between lunar tidal forces, Earth’s internal structure, and its thermal evolution, offering insights into the complex dynamics of our planet’s interior. Full article

With the rapid development of battery energy storage technology, the issue of thermal runaway (TR) in lithium-ion batteries has become a key challenge restricting their safe application. This study presents an innovative protection strategy that integrates liquid cooling with sodium acetate trihydrate (SAT)-based composite phase change materials (CPCM) to mitigate TR and its propagation in prismatic battery modules. Through numerical simulation, this study systematically investigates the TR protection mechanism and optimization pathways for prismatic battery modules. The results indicate that pure SAT exhibits poor latent heat performance due to its low thermal conductivity. In contrast, the incorporation of expanded graphite (EG) significantly enhances thermal conductivity and improves the overall latent heat performance. Compared to traditional paraffin-expanded graphite (PA-EG), SAT-EG, with a latent heat 4.8 times higher than that of PA-EG, demonstrates more than six times the effectiveness in delaying thermal runaway propagation (TRP). When combined with liquid cooling, the TR protection effect is further enhanced, and TR will not be triggered when the initial abnormal heat generation rate is relatively low. Even if an abnormal battery experiences TR, its propagation will be prevented when the thickness of the SAT-EG exceeds 12 mm. Ambient temperature influences both the peak temperature and the timing of its occurrence in the battery module. Among the different liquid cooling layouts, the combined bottom and side cooling scheme exhibits superior performance compared to the standalone schemes. Full article

The impact of high temperatures on tourist flows in urban and rural areas is both complex and multi-dimensional, yet research remains limited regarding their spatial and temporal differences. This study aims to analyze the changes in tourist flows between urban and rural areas under high-temperature conditions and to identify the key factors driving these patterns, contributing to climate-resilient tourism planning. Using Shanghai, China, as a case study, we constructed an attraction-based tourist flow model with Baidu migration data, integrating a self-organizing feature map for urban–rural classification and Pearson correlation analysis to examine influencing factors. The results showed that high temperatures significantly reduced tourist flows in both urban and rural areas, with a more pronounced impact observed in rural areas. This reduction altered spatial patterns, shifting from a multicentric distribution to an urban-centered concentration. Furthermore, high temperatures affected the timing of tourist flows differently across regions. In urban areas, tourist flows tended to start earlier, and key driving factors, such as facility services and economic levels, remained stable and continued to exert a dominant influence. In contrast, rural tourist flows were delayed under high-temperature conditions, with tourists showing a preference for cooler attractions further from urban centers. These findings highlight the need for targeted climate adaptation strategies, including improving cooling infrastructure in urban areas and promoting eco-friendly, sustainable tourism initiatives in rural regions. This study offers empirical evidence to support policy efforts aimed at fostering coordinated urban–rural tourism development and advancing sustainable adaptation to climate change. Full article

The traditional optimal scheduling of air conditioning load has traditionally focused on improving user comfort and reducing electricity costs. However, research on carbon emissions generated during the operation of air conditioning is still in the developmental stage. Currently used average carbon emission factors in carbon-emission studies face challenges such as delayed data updates and difficulty in reflecting spatiotemporal variations. These issues contribute to the inaccurate quantification of carbon emissions, creating a challenging situation, which does not meet the development needs of green power systems under the “dual carbon goals”. Therefore, this paper proposes a multi-objective scheduling method for cooling-dominant air conditioning load considering the dynamic carbon emission factor (CEF), in conjunction with real-time spatiotemporal data from the electricity grid model, generates the electric carbon factor for each moment throughout the day. Firstly, while considering user comfort, the dynamic CEF-based carbon-emission cost and electricity cost are fused into the user’s comprehensive electricity cost, and a multi-objective optimization model for day-ahead scheduling of air conditioning loads is established. In addition, the above model is solved by the NSGA-II algorithm to obtain the Pareto front composed of non-dominated solutions. Then, the best compromise solution is objectively selected through gray target decision (GTD) to provide scientific decision-making for day-ahead scheduling of cooling-dominant air conditioning loads. Finally, four users with different air conditioning loads and room temperature requirements are designed to verify the effectiveness of the proposed strategy. The simulation results illustrate that compared with single-objective optimization and simple multi-objective decision-making methods, the proposed strategy possesses a stronger trade-off ability, which can greatly reduce the comprehensive electricity cost while ensuring user comfort. Full article

Background/Objectives: Ischemic time plays a crucial role in graft function and survival during kidney transplantation. Cooling methods, including cold perfusion and ice slush, are predominantly applied to preserve the kidney, but they may cause uneven cooling and complications. The Organ Pocket^®, an insulated gel bag, has been introduced as an alternative cooling method. However, no studies have compared renal temperature changes between the Organ Pocket^® and conventional cooling methods. Methods: We retrospectively analyzed 49 cases of living-donor kidney transplantation. Among these, 33 received kidney grafts preserved with the Organ Pocket^® (OP group), and 16 underwent conventional cooling (control group). Renal surface temperatures were recorded at 5 min intervals during vascular anastomosis using thermography. Postoperative renal function was assessed with estimated glomerular filtration rate (eGFR), serum creatinine (sCr), and liver-type fatty acid-binding protein (L-FABP) levels. Results: The OP group demonstrated significantly higher renal surface temperatures than the control group during vascular anastomosis (p < 0.05). Renal surface temperature before reperfusion was 20.4 °C ± 2.5 °C and 17.2 °C ± 2.5 °C in the OP and control groups, respectively. No significant differences in postoperative eGFR, sCr, and L-FABP levels; delayed graft function (DGF); or acute rejection rates were observed between the groups. Conclusions: The Organ Pocket^® effectively stabilized renal temperatures during vascular anastomosis without direct cooling, thereby reducing continuous manual cooling requirements. Short-term renal function outcomes were comparable between groups; however, the Organ Pocket^® may improve surgical efficiency and be particularly beneficial in robot-assisted kidney transplantation. Further studies are warranted to investigate its long-term benefits. Full article

Evidence supports the role of palmar cooling to improve exercise performance, especially with endurance and resistance activities. The aim of this randomized placebo-controlled trial was to explore the effects of palmar cooling on repeated sprinting performance and recovery. Fifteen graduate students were randomly assigned to either a palmar cooling intervention or placebo group (males: n = 8, females: n = 7; Avg. age: 24.06 yrs.) After a ten-minute warm-up, participants completed ten sixty-meter sprints that included two 180-degree changes of direction. Three bouts of two-minute intervention or placebo occurred during the study. Data for sprint times, heart rate, and RPE were collected throughout testing. A muscle soreness rating was collected via survey 48 h post intervention. Statistically and practically significant differences were found between groups for average sprint times, heart rate, and delayed onset muscle soreness. The intervention group utilizing palmar cooling demonstrated less degradation in sprint times, lower heart rate upon completion, and a lower soreness rate 48 h after testing. More research is needed with a larger sample size to determine if practical and statistically significant differences will be maintained and would allow for a more robust multivariant analysis, resulting in the findings being more generalizable to a larger population. Full article

As a critical component of nuclear power units, the direct cooling water system plays a key role in overall performance. To maintain economic efficiency, it is necessary to adjust the circulating water flow rate as conditions change. Understanding how this system responds dynamically to varying environmental factors—such as seawater temperature and tidal levels—is essential for precise control. While previous studies have explored methods such as variable frequency control, predictive maintenance, and digital twin technologies to optimize system operations, challenges remain in addressing the dynamic response of cooling systems under complex environmental and operational conditions. In this study, the AP1000 was used as the research subject and a comprehensive mathematical model of each part of the cooling water system was built, accounting for delays in processes like pipeline transport. Sensitivity analyses were then carried out to examine how linear disturbances in environmental parameters affect system performance, and how circulating water flow, condenser back pressure, and unit efficiency are interrelated. At the same time, the frequency conversion circulating water pump adaptive adjustment system is used to find the best vacuum conditions according to the change in seawater parameters. The findings offer valuable guidance for enhancing the economic operation of nuclear power plant cooling systems. Full article

The Antarctic sea ice concentration (SIC) plays a crucial role in global climate dynamics by influencing atmospheric and oceanic circulation. This study examines SIC variability and its relationship with major climate modes, including the El Niño-Southern Oscillation (ENSO), Pacific-South American (PSA) pattern, Southern Annular Mode (SAM), and Antarctic Dipole (ADP). Using NSIDC satellite-derived sea ice data and ERA5 reanalysis from 1980 to 2022, we analyzed SIC anomalies in the Weddell, Ross, and Bellingshausen and Amundsen (B&A) Seas, assessing their response to climatic forcings across different timescales. Our findings reveal strong linkages between SIC variability and large-scale atmospheric circulation. ENSO-related teleconnections drive a dipolar SIC response, with warming in the Pacific sector and cooling in the Atlantic during El Niño, and the opposite pattern during La Niña. PSA and ADP further modulate this response by altering Rossby wave propagation and heat fluxes, leading to significant SIC fluctuations. The ADP emerges as a dominant driver of interannual SIC anomalies, showing an out-of-phase relationship between the Atlantic and Pacific sectors of the Southern Ocean. Regional SIC trends exhibit contrasting patterns: the Ross Sea shows a significant positive SIC trend, while the B&A and Weddell Seas experience persistent negative anomalies due to enhanced meridional heat transport and stronger westerly winds. SAM strongly influences SIC, particularly in the Atlantic sector, with delayed responses of up to six months, likely due to ice-albedo feedbacks and ocean memory effects. These results enhance our understanding of Antarctic sea ice variability and its sensitivity to large-scale climate oscillations. Given the observed trends and ongoing climate change, further research is needed to assess how these processes will evolve under future warming scenarios. This study highlights the importance of continuous satellite observations and high-resolution climate modeling for improving projections of Antarctic sea ice behavior and its implications for the global climate system. Full article

Improving user-level energy efficiency is critical for reducing the load on the power grid and addressing the challenges created by tight power balance when operating domestic air conditioning equipment under time-of-use (ToU) pricing. This paper presents a data-driven control method for HVAC (heating, ventilation, and air conditioning) systems that is based on model predictive control (MPC) and takes ToU electricity pricing into account. To describe building thermal dynamics, a multi-layer neural network is constructed using time-delayed embedding, with the rectified linear unit (ReLU) serving as the activation function for hidden layers. Using this piecewise affine approximation, an optimization model is developed within a receding horizon control framework, integrating the data-driven model and transforming it into a mixed-integer linear programming issue for efficient problem solving. Furthermore, this research suggests a hybrid optimization model for integrating air conditioning systems and battery energy storage systems. By employing a rolling time-domain control method, the proposed model minimizes the frequency of switching between charging and discharging states of the battery energy storage system, improving system reliability and efficiency. An Internet of Things (IoT)-based home energy management system is developed and validated in a real laboratory environment, complemented by a distributed integration solution for the energy management monitoring platform and other essential components. The simulation results and field measurements demonstrate the system’s effectiveness, revealing discernible pre-cooling and pre-charging behaviors prior to peak electricity pricing periods. This cooperative economic operation reduces electricity expenses by 13% compared to standalone operation. Full article

Phase change modeling in porous media is among the important challenges in many essential engineering problems, including thermal management, energy conservation or recovery, and heat transfer. One particularly efficient method of dissipating heat in a porous material is transpiration cooling with phase change. It is one of the most innovative cooling methods available for removing excessive heat flux from engine components such as combustors or gas turbine blades. There is, however, a lack of in-depth understanding of the interconnected mechanisms involved in such an application. In this work, an innovative numerical solver built on the OpenFOAM environment is constructed in order to explore the phase change process in a porous medium. The volume-of-fluid method and the Lee phase change model are applied in this numerical approach. The effects of coolant flow mass rate, heat flux, and porosity of porous structure on temperature and saturation distribution are investigated and discussed. The effects of both the external heat flux and the coolant mass flow rate under fixed porosity are also studied. The phase change is then delayed in the porous matrix when the amount of the injected coolant is increased. It reduces the area of two-phase and vapor regions. Also, a considerable rise in the upper surface temperature is obtained when the input heat flux or the porosity is separately enhanced. Full article

In crude oil storage tank fires, large amounts of firefighting water are used, which may trigger boilover. Variations in oil level affect ullage height, while firefighting water injection alters the water layer thickness, with both processes influencing boilover behavior. This study conducts boilover experiments with 3 types of crude oil to investigate the effects of ullage height and water layer thickness. The results show that the water-cooling effect delays boilover onset time, suppresses intensity, and reduces the mass burning rate, with Jidong crude showing the highest reduction (19.2%). However, the water-cooling effect has a limit, and its influence weakens when the water layer thickness exceeds 6 cm. Ullage height affects flame behavior. A moderate increase enhances combustion and shortens boilover onset time, while further increases cause self-extinction. The oil–water interface temperature varies nonlinearly between approximately 100 and 120 °C with changing ullage height. The variation trends of hot wave propagation rate with water layer thickness and ullage height are consistent with those of the burning rate, and correlation equations between them are established. Additionally, the study shows that light crude oil exhibits a later boilover onset with a longer duration and experiences 2~3 distinct boilover events, whereas high-viscosity Jidong crude oil undergoes a single short and intense boilover. Full article

Fruits are perishable fresh products with a short shelf life after harvesting. Perishable foods and their shelf lives are directly related to the temperature at which they are stored. Refrigeration is therefore essential in the conservation of fruits, as it allows the temperature to be lowered, helping to delay microbial, physiological, and chemical changes. This work aimed to compare the thermal behaviors of alveoli with different phase change materials (PCMs) placed inside a modular packaging developed for the transport and storage of fruits. The cooling tests were carried out inside a cold storage chamber with the set-point programmed to 2 °C. To simulate the placement in packages exposed to the store environment, heating tests were carried out while the chamber door was opened and the packaging was exposed to external environmental conditions. The phase change materials tested were RT2HC, RT5HC, and RT8HC. The temperature variation in the tests during cooling and heating proved that the new type of alveoli with PCM inside the fruit transport packaging is extremely important, as it can extend the useful life of the fruits after they are removed from the cold chamber, managing to maintain adequate conservation conditions for longer in contact with room temperature. The phase change material RT8HC was the one that showed the best results overall, managing to maintain the temperature of the fruit inside the packaging at a temperature below 10 °C for up to eight hours after being exposed to ambient conditions of 20 °C. Full article

Vaccination cold chains depend critically on maintaining temperatures within the 2–8 °C range, with phase-change materials (PCMs) like n-tetradecane offering substantial potential due to their high latent heat and optimal melting characteristics. Despite extensive research on PCM melting enhancement, strategies to extend melting duration and thermal stability remain underexplored. This pioneering numerical study investigates the impact of incorporating 5% glycerol additive in n-tetradecane, aiming to decelerate the melting rate and sustain the desired temperature range over prolonged periods. This study numerically assesses the effect of a 5% glycerol additive on n-tetradecane, revealing a substantial 20.6 h extension in safe temperature maintenance, from 123.3 h in pure n-tetradecane (T) to 143.9 h with the additive (T + G). Although T reaches full melting in 121.7 h, the air temperature inside the cold box breaches 8 °C only 1.6 h after; in contrast, T + G reaches this threshold 2.2 h before full melting, resulting in an effective extension of 20.6 h. Entropy analysis shows a delayed rise in T + G, indicating enhanced thermal stability, while temperature contours confirm T + G sustains cooling until day 6, a full day beyond T. These findings highlight glycerol’s potential to modulate thermal dynamics within PCM-based cold boxes, offering a cost-effective improvement in vaccine transport sustainability. Full article