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This paper presents an optimized energy management strategy for Li-ion power batteries used on electric vehicles (EVs) at low temperatures. In low-temperature environments, EVs suffer a sharp driving range loss resulting from the energy and power capability reduction of the battery. Simultaneously, because of Li plating, battery degradation becomes an increasing concern as the temperature drops. All these factors could greatly increase the total vehicle operation cost. Prior to battery charging and vehicle operating, preheating the battery to a battery-friendly temperature is an approach to promote energy utilization and reduce total cost. Based on the proposed LiFePO4 battery model, the total vehicle operation cost under certain driving cycles is quantified in the present paper. Then, given a certain ambient temperature, a target preheating temperature is optimized under the principle of minimizing total cost. As for the preheating method, a liquid heating system is also implemented on an electric bus. Simulation results show that the preheating process becomes increasingly necessary with decreasing ambient temperature, however, the preheating demand declines as driving range grows. Vehicle tests verify that the preheating management strategy proposed in this paper is able to save on total vehicle operation costs.

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.

Anthocyanins (ANs) have strong antioxidant activities and can inhibit chronic diseases, but the instability of ANs limits their applications. The conservation of preheating whey protein concentrate (WPC) on the stability of purple sweet potato ANs was investigated. The retention of ANs in WPC-ANs was 85.88% after storage at 25 °C for 5 h. WPC-ANs had higher retention of ANs in heating treatment. The retention rates of ANs in WPC-ANs exposed to light and UV lamps for 6 h were 78.72% and 85.76%, respectively. When the concentration of H2O2 was 0.50%, the retention rate of ANs in the complexes was 62.04%. WPC-ANs’ stability and antioxidant activity were improved in simulated digestive juice. The WPC-ANs connection was static quenching, and the binding force between them was a hydrophobic interaction at one binding site, according to the fluorescence quenching spectroscopy. UV-visible absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR) analysis further indicated that the secondary structure and microenvironment of amino acid residues in WPC can be impacted by the preheating temperature and preheating times of WPC. In conclusion, preheating WPC can successfully preserve the stability of purple sweet potato ANs by binding to them through a non-covalent interaction.

With the increasing demand for renewable energy worldwide, lithium-ion batteries are a major candidate for the energy shift due to their superior capabilities. However, the heat generated by these batteries during their operation can lead to serious safety issues and even fires and explosions if not managed effectively. Lithium-ion batteries also suffer from significant performance degradation at low temperatures, including reduced power output, a shorter cycle life, and reduced usable capacity. Deploying an effective battery thermal management system (BTMS) is crucial to address these obstacles and maintain stable battery operation within a safe temperature range. In this study, we review recent developments in the thermal management and heat transfer of Li-ion batteries to offer more effective, secure, and cost-effective solutions. We evaluate different technologies in BTMSs, such as air cooling, liquid cooling, phase change materials, heat pipes, external preheating, and internal preheating, discussing their advantages and disadvantages. Through comparative analyses of high-temperature cooling and low-temperature preheating, we highlight the research trends to inspire future researchers. According to the review of the literature, submerged liquid BTMS configurations show the greatest potential as a research focus to enhance thermal regulation in Li-ion batteries. In addition, there is considerable research potential in the innovation of air-based BTMSs, the optimization of liquid-based BTMSs, the coupling of heat pipes with PCMs, the integration of PCMs and liquid-cooled hybrid BTMSs, and the application of machine learning and topology optimization in BTMS design. The application of 3D printing in lithium-ion battery thermal management promises to enhance heat transfer efficiency and system adaptability through the design of innovative materials and structures, thereby improving the battery’s performance and safety.

A bstract Oscillons are long-lived, localized excitations of nonlinear scalar fields which may be copiously produced during preheating after inflation, leading to a possible oscillon dominated phase in the early Universe. For example, this can happen after axion monodromy inflation, on which we run our simulations. We investigate the stochastic gravitational wave background associated with an oscillon-dominated phase. An isolated oscillon is spherically symmetric and does not radiate gravitational waves, and we show that the flux of gravitational radiation generated between oscillons is also small. However, a significant stochastic gravitational wave background may be generated during preheating itself (i.e, when oscillons are forming), and in this case the characteristic size of the oscillons is imprinted on the gravitational wave power spectrum, which has multiple, distinct peaks.

Moderate or intense low‐oxygen dilution (MILD) combustion has garnered significant attention for its high temperature uniformity and ultra‐low NOx emissions in recent years. To achieve ultra‐low NOx emissions in the coking industry, a laboratory‐scale long‐narrow confined furnace (LNCF) system based on the coke oven heat flue was established to investigate the combustion characteristics of conventional and MILD combustion of coke oven gas (COG) in a long‐narrow confined space. Different operating parameters (air excess ratio, dilution type and preheating temperature [ T ox ]) were carried out. The results show that the optimal temperature uniformity is achieved at an air excess ratio of 1.2 in conventional combustion. A comparative analysis of different dilution types revealed that single‐fuel dilution (SFD) and flue gas dual‐dilution (FGDD) are more effective than single‐air dilution (SAD) in achieving MILD combustion, and reducing the T ox can result in a reduction in the critical dilution ratio ( θ ). The temperature uniformity ratio is increased in conventional combustion but reduced in MILD combustion by increasing the T ox , indicating that increasing the T ox effectively enhances the temperature uniformity in MILD combustion. The optimal temperature uniformity in MILD combustion can be obtained through FGDD at T ox = 873 K and θ = 50%. FGDD is more effective for mixing intensity than SFD and SAD, promoting complete reactions between reactants and effectively reducing CO emissions. Compared with SAD, SFD, and FGDD are more conducive to achieving clean NO emissions in the MILD combustion regime. Clean MILD combustion can be achieved at 573 K ≤ T ox ≤ 673 K and θ = 50%, regardless of the dilution type.

Directed energy deposition (DED), one of the additive manufacturing (AM) technologies, was used to realize AISI 316L specimens. The role of substrate preheating on the microstructure, hardness, surface roughness, and mechanical properties of AISI 316L samples was studied using two groups of deposited samples on a cold substrate and a preheated one. The cooling rate in each specimen was determined using primary cellular arm spacing (PCAS). It is found that the thermal gradient and cooling rate in the samples produced on the preheated substrate are lower. However, in both cases, the cooling rate decreased as the deposition height increased. The phase composition analysis confirmed that the lower cooling rate in the preheated samples resulted in a lower residual δ-ferrite content. The deeper microstructural analysis also confirmed the formation of non-metallic inclusions during the building process. However, the quantity of these inclusions was lower in the samples realized on the cold substrate. Preheating the base plate had a negligible effect on the surface roughness of the AISI 316L cubes. The tensile results demonstrated that the samples produced using the cold base plate had better mechanical performance than those deposited on the preheated base plate. All in all, using a preheated substrate led to a lower thermal gradient, lower cooling rate, larger PCAS, higher inclusion content, higher oxygen pick-up, and lower nitrogen pick-up that strongly affected the mechanical characteristics of the AISI 316L samples.

Objective This study aimed to evaluate the effect of various preheating methods applied to bulk-fill composite resins on temperature changes within the pulp chamber. Materials and Methods Ten sound human molars were used. Each tooth was sectioned 2 mm apical to the cementoenamel junction, and the occlusal surface was flattened to leave a 2 mm dentin thickness. Four bulk-fill composite resins were applied at five temperatures (24 °C, 37 °C, 54 °C, 65 °C, and 68 °C) and polymerized using an LED curing unit. Intrapulpal temperature changes were measured with a K-type thermocouple connected to a data logger in a setup simulating pulpal microcirculation. In total, twenty measurements were taken per tooth under each condition. Data were analyzed using one-way ANOVA and post-hoc LSD tests ( p  < 0.05). Results The highest intrapulpal temperature increase was observed at 65 °C in all groups using the VisCalor dispenser. The critical temperature threshold was not exceeded in any sample. Significant differences were found between certain temperatures within individual resin groups ( p  < 0.05), particularly at 65 °C compared to lower temperatures. However, no statistically significant differences were found between different resin types at the same temperatures ( p  > 0.05). Conclusion Preheating of bulk-fill composite resins led to an increase in intrapulpal temperature; however, this rise remained below the threshold that could cause irreversible pulpal damage. Clinical relevance Preheating bulk-fill composites enhances handling and adaptation but may increase intrapulpal temperature. In this study, the temperature rise remained below the critical threshold, suggesting that the procedure is clinically safe.

The 12CrNi2 alloy steel powder studied in the present paper is mainly used to manufacture camshafts for nuclear power emergency diesel engines. Laser cladding deposition is of great significance for the manufacture of nuclear power emergency diesel camshafts, which has the advantages of reducing material cost and shortening the manufacturing cycle. However, due to the extremely uneven heating of the components during the deposition process, a complex residual stress field occurs, resulting in crack defects and residual deformation of the components. In the present paper, 12CrNi2 bulk specimens were prepared on the Q460E high-strength structural steel substrate at different preheating temperatures by laser cladding deposition technique, and a finite element residual stress analysis model was established to investigate the effects of different preheating temperatures on the microstructure, properties, and residual stress of the specimens. The results of the experiments and finite element simulations show that with the increase of preheating temperature, the content of martensite/bainite in the deposited layer decreases, and the ferrite content increases. The proper preheating temperature (150 °C) has good mechanical properties. The residual stress on the surface of each specimen decreases with the increase of the preheating temperature. The longitudinal stress is greater at the rear-end deposition part, and the lateral residual stress is greater on both sides along the scanning direction.

This study develops a combined preheating and passive cooling strategy to maintain a 2170 lithium-ion battery (LIB) within its optimal operating temperature range of 15–35 °C under freezing conditions. A computational fluid dynamics (CFD) model based on the finite volume method (FVM) is employed to simulate a thermal management structure composed of high-porosity Al₂O₃ foam (ε = 0.9) impregnated with hexadecane as the phase change material (PCM), coupled with an external preheating technique. This work provides a system-level assessment of preheating duration, energy consumption, PCM utilization, and thermal regulation under extreme cold-start conditions down to − 40 °C, demonstrating stable temperature uniformity, effective latent heat absorption, and improved thermal safety for cold-climate battery applications. The results show that the preheating stage effectively raises the cell temperature to 15 °C, while the PCM–Al₂O₃ foam matrix maintains the temperature below 35 °C during discharge. Across all operating conditions, both the average temperature (T avg ) and maximum temperature (T max ) increase with C-rate and environmental temperature. At low C-rates (1–2 C), the available PCM capacity is sufficient to maintain T avg = 20 °C and keep T max near this level until the end of discharge, whereas at higher C-rates (3–4 C), T avg and T max rise above 20 °C once the PCM approaches complete melting.