Search Results (4,846)

Phase-change materials (PCMs), such as paraffin wax, are widely used in latent heat storage (LHS) because they store substantial thermal energy at nearly constant temperature; however, their low thermal conductivity limits heat transfer and slows melting/solidification. In this work, two flat-plate solar collectors are coupled with a paraffin-based LHS unit for low-temperature solar heating, and the design is optimized by introducing improved fin-geometry combinations on both the heat transfer fluid (HTF) tube and shell side. The M-shaped fins combined with rectangular fins significantly enhanced convective heat transfer by generating localized vortices, while the extended surface area improved conduction within the solid PCM, facilitating efficient heat dissipation and accelerating the phase transition. The LHS unit without fins showed complete melting in 67 min. However, fin introduction remarkably mitigated charging duration to 44 min, 52.3% faster than bare tubes having no fins. The experimental melting process exhibited a 7 min delay by comparing experimental and numerical results, achieving complete melting in 51 and 44 min, respectively. Discharging was completed in 48 min. During PCM charging, sensible heating produces a rapid temperature rise with only a small energy increase, but once the PCM entered into the melting range (320–324 K), the energy changed more steeply. Adding fins boosts stored energy from 2.10 MJ to 3.25 MJ (54.8%) and exergy from 0.15 MJ to 0.27 MJ (80.0%), yet exergy remains far smaller than energy (92.9% lower without fins and 91.7% lower with fins), indicating fins enhance total heat storage more than recoverable work potential. Full article

Steels remain among the most widely used structural and engineering materials in modern infrastructure, energy systems, and industrial facilities. Their long-term reliability depends critically on the early detection of corrosion damage and microstructural degradation. This review surveys recent advances in two complementary families of non-destructive evaluation (NDE) methods: magnetic techniques, including magnetic Barkhausen noise (MBN), magnetic flux leakage (MFL), eddy current testing (ECT), and magnetic hysteresis analysis; and electrochemical methods including electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), scanning vibrating electrode technique (SVET), and electrochemical noise (EN). Recent progress in sensor miniaturization, signal processing algorithms, and multi-technique integration is reviewed. Particular attention is given to the sensitivity of these methods to microstructural changes reported in the literature, including carbide dissolution, phase transformations, temper embrittlement, and sensitization in stainless steels, as well as to the conditions under which such sensitivity has been demonstrated. The potential synergy between magnetic and electrochemical monitoring is discussed as a possible pathway toward more robust, condition-based maintenance frameworks. Challenges related to field deployment, environmental interference, calibration, and data interpretation are identified, and future directions—including machine learning-assisted analysis and multi-physics sensor arrays—are outlined. Full article

This study investigates the thermal performance of a flat-plate phase-change thermal energy storage system, focusing on two structural innovations: a cascaded arrangement of multiple phase-change materials (PCMs) with varying melting points, and the implementation of series/parallel flow configurations. A combined numerical and experimental approach is employed to analyze dynamic charging/discharging behavior. Quantitative results indicate that the cascaded configuration (three PCMs) reduces phase-change completion time by 13% and increases cooling energy storage power from 2.00 kW to 2.43 kW during charging compared to single-PCM systems. Flow configuration significantly impacts thermal response: the parallel layout delivers more stable cooling output, while the series layout achieves faster initial cooling (reaching 6.24 °C within 1200 s, 31% faster than the parallel layout). Experimental results reveal that inlet water temperature is the most critical operating parameter, with each 2 °C increase significantly prolonging charging time. This work offers practical guidance for the design and optimization of efficient cascaded PCM thermal storage systems. Full article

This study investigated waste segregation awareness and behavior, developed awareness-promoting activities, and evaluated their effectiveness among lower secondary school students in Phitsanulok Province, Thailand. The research was conducted in three phases: Phase I involved baseline data collection using interviews and structured observations. Phase II focused on developing awareness-promoting activities, including training workshops, printed public relations materials, video-based learning, and game-based waste segregation. Phase III evaluated the effectiveness of interventions using a pre-test–post-test design. The research instruments included awareness and behavior questionnaires, behavior observation forms, and records of segregated solid waste quantities. The results showed significant increases in awareness and waste segregation behavior scores after the intervention across all activity types (all p < 0.001). The mean awareness scores increased from 10.27 to 12.74 (p < 0.01), and mean waste segregation behavior scores increased from 11.82 to 13.64 (p < 0.001). However, after adjustment for pre-intervention scores and school, no significant differences were observed among activity types. Higher awareness levels were positively associated with improved waste segregation behavior, as reflected by changes in waste quantity and composition. These findings indicate that awareness-promoting activities can effectively enhance source-based waste management practices and may be applied in similar municipal and educational contexts. Full article

Mechanochromism is a phenomenon in which mechanical stimuli change the optical properties of a material, such as its color and emission properties. Various materials exhibiting this behavior have been intensively studied. Mechanochromic materials that exploit liquid crystals have been previously reported. Using liquid crystals, properties different from those of conventional materials, such as anisotropic response and multicolored luminescence due to intermediate aggregation phase stabilization, can be expected. Recently, we reported the preparation and evaluation of the optical properties of liquid-crystalline mechanochromic dyes with cholesterol terminals. The dyes formed gels in some solvents, changed their emission color, and exhibited a friable response without reaching a crystalline state. In addition, film-forming properties, processability, and responsiveness were improved in thin films mixed with polymers. However, the mechanical and thermal stabilities of the gels were low. In this study, a compound similar to the polymerizable unit was synthesized to produce tougher gels. In addition, triblock polymers with a mechanoresponsive dye in the hard segment were synthesized. The xerogel film prepared from the monomer showed an irreversible blue shift in photoluminescent color by mechanical grinding and also exhibited linearly polarized photoluminescence by uniaxial grinding due to force-induced alignment. On the other hand, the xerogel film prepared from the triblock copolymer showed a blue shift in photoluminescent color that can approximately revert to the initial state by thermal annealing, though it showed no anisotropy by uniaxial grinding, indicating that polymerization partially preserves mechanical responsiveness. Full article

Elastocaloric cooling, which leverages stress-induced phase transformation in shape memory materials, represents a sustainable and energy-efficient alternative to conventional vapor-compression cooling systems. Central to optimizing these materials is understanding how thermal processing history dictates phase formation, microstructure, and thermal properties. In this study, we investigated the (Ni₅₀Mn_31.5Ti₁₈)_99.8B_0.2 compound synthesized via vacuum induction melting and arc melting, followed by water quenching. Induction melting results in needle-like, boron-rich precipitates within the martensite lattice. In contrast, vacuum arc melting promoted precipitate growth at the grain boundaries. The vacuum arc melting sample exhibits ~82% martensite phase fraction, a near-ambient transformation temperature of ~277 K, a large transition entropy change of ~75 J·kg⁻¹·K⁻¹, and moderate thermal hysteresis of ~24 K. These results underscore the pivotal role of thermal history in tailoring phase stability and transformation thermodynamics, providing essential design guidelines for subsequent mechanical performance optimization in elastocaloric shape memory alloys for energy-efficient and sustainable thermal management applications. Full article

Shot-peening treatments improve the fatigue performance of mechanical components thanks to the surface modifications introduced and mainly due to the residual compressive stresses present in the layer of material near the shot-peened surface. There is no unanimous agreement in scientific literature regarding the kinetics of the damage process. However, it is generally accepted that, due to morphological and microstructural changes in the shot-peened layer, the material is more prone to early crack initiation, the propagation of which is then significantly slowed down or even stopped by the local stress field. This work focuses on applying the acoustic emission (AE) technique to detect fatigue crack initiation and propagation in shot-peened Al-alloy components. The analysis is conducted on Al-7075-T6 alloy, subjected to different shot-peening conditions and fatigue tested under alternating four-point bending. The results from the AE analyses are then correlated with a fractographic analysis. For all shot-peening conditions investigated, acoustic emission consistently indicated probable crack nucleation at approximately two-thirds of the total fatigue life, followed by a significant damage accumulation phase prior to dominant crack propagation. The final increase in acoustic activity coincided with the measurable loss of stiffness, confirming the onset of accelerated crack growth leading to fracture. The results demonstrate that, despite some experimental challenges, AE monitoring has the potential for the early detection of damage initiation. Full article

Scarce global resources and reliance on non-renewable materials demand ecological, technology-integrated solutions. In Brazil, abundant wood resources remain underused in architectural education and practice. Introducing skills in curricula is essential for change and future adoption. This study developed a computational and digital fabrication methodology to rethink wood, exploring collaborative robotic assembly to build an embodied understanding of construction constraints. The Wood Innovation for Architecture in Brazil (WI-FAB) unites LAMO UFRJ and SDU CREATE robotics expertise and frames a pedagogical experiment in sustainable wood-structure design. The semester-long course tested whether the design framework could link computation, material behaviour, and assembly constraints as a pedagogical tool; the intensive workshop investigated how robotic assembly can enhance physical–digital workflows and inform future integration. The research-through-teaching methodology consisted of three phases: preliminary research, course testing, and a robotics workshop testing assembly workflows. Preliminary research developed a pedagogical framework comprising a kit of parts, joint types and string grammars tested within the semester-long course to support parametric rules and assembly sequencing. Participants assembled component “letters” that combined into “words” and then into “phrases”, developing computational and constructional understanding and converting parametric rules into tangible prototypes through iterative design-build-test cycles. Key outcomes include validation of parametric assembly rules through string grammars in the course; analysis of the robotics workshop applied four criteria (Assembly Movement; Component Geometry and Dimensions; Component Number and Slot Number; Complexity and Assembly Time) to evaluate assembly performance and workflow integration. Robotics stimulated physical–digital loops, accelerating design-to-assembly learning and informing full-scale developments. WI-FAB promotes reversible assembly, material reuse and circular-economy principles and contributes to the development of the forthcoming Sabiá parametric plugin for wooden joint design. Full article

To overcome the limitations imposed by the intermittent nature of sunlight in photocatalytic applications, this research constructs a round-the-clock purification system. We integrated an optimized S-scheme CoFe₂O₄/BiVO₄ (CFO/BV) heterojunction (synthesized via ultrasonic self-assembly at a 0.5:0.5 ratio) with a thermal energy storage (TES) unit consisting of SiO₂-encapsulated Na₂SO₄·10H₂O phase change materials (PCMs). Comprehensive characterization techniques, including XRD, HRTEM, UV-Vis DRS, EPR, and DSC, confirmed the successful formation of the interface, a broadened visible-light response (λ > 650 nm), efficient radical production, and a high latent heat storage capacity (>200 J/g). Under simulated solar irradiation, the composite exhibited superior performance, degrading 98% of the Rhodamine B within 6 h (k = 0.00994 min⁻¹), significantly surpassing single-component counterparts. More importantly, during the subsequent 12 h dark period, the heat released from the PCM maintained the reaction temperature above 35 °C, driving a 64% degradation efficiency via a thermocatalytic pathway. The system demonstrated robust stability (>90% efficiency after five cycles), excellent magnetic recoverability (98%), and high tolerance to saline textile wastewater (<10% activity loss). Furthermore, Life Cycle Assessment (LCA) indicated a 40% reduction in energy consumption compared to conventional UV/TiO₂ processes, highlighting a sustainable strategy for continuous wastewater remediation through synergistic photocatalysis and thermocatalysis. Full article

The rising environmental impact of building energy consumption has intensified the demand for sustainable energy solutions. Latent heat thermal energy storage (LHTES) using phase-change materials (PCMs) offers a highly effective approach to improve energy efficiency; however, the intrinsically low thermal conductivity of most PCMs limits their practical performance. This study explores the thermophysical properties of a commercially available bio-based PCM (CrodaTherm^TM 60) enhanced with graphene nanoplatelets (GNPs) to improve heat transfer performance. Nano-enhanced PCMs (NePCMs) were prepared using a two-step process combining magnetic stirring and ultrasonication, incorporating GNPs at 2, 4, and 6 wt.%. Solid-phase density measurements of the NePCMs and viscosity measurements of the pure PCM were also conducted to support material characterisation. The results indicate distinct behaviours for the two nanoparticle sizes. At 6 wt.% nanoparticle loading, for 2 nm particles, the thermal conductivity increases by up to 13.9%, whereas for 6–8 nm particles, the enhancement is 148.9% of the pure PCM. Additionally, a reduction in latent heat is observed, with a proportional relationship to mass loading, as expected. These findings underscore the need for improved nanoparticle dispersion and formulation strategies to optimise both thermal performance and stability. Full article

The intermittent and variable nature of solar energy poses challenges for maintaining stable thermal performance in solar heating systems. One effective approach to mitigate this limitation is to store surplus thermal energy during periods of high solar irradiance and release it when solar input is insufficient. Phase change materials (PCMs) are particularly suitable for this purpose due to their ability to absorb and release large amounts of latent heat during phase transition. The aim of this work is to develop a mathematical model of a flow-through tank containing a phase change material in the form of a spherical packed bed. Including longitudinal dispersion in the model equations allows for a more accurate description of the heat transfer process in a tank containing PCM elements. Simulation calculations based on the model were carried out to demonstrate its potential applicability to practical problems. The influence of the following parameters on the process was investigated: tank volume, water flow rate, phase change temperature, process duration, dispersion coefficient during water flow, radius of the packed-bed elements, and cyclic variations of the inlet water temperature. A significant influence of the axial dispersion coefficient in the tank containing PCM on the outlet water temperature profile was demonstrated. It was found that the internal heat transfer coefficient within the packing elements containing PCM falls within the range of 58–145 W/(m²K). Full article

Backround and Objectives: Basketball performance is shaped by repeated high-intensity actions interspersed with brief recovery. Conventional continuous or strictly incremental testing may not fully capture short active-recovery dynamics relevant to stop-and-go sports. Material and Methods: This study applied a VT₂-referenced progressive–intermittent treadmill protocol and focused on 60-s active-recovery kinetics to describe effort tolerance in an applied basketball setting. Basketball players from Mureș County completed anthropometry (24 h pre-test, fasted) and a single laboratory visit. Pre-test training and diet were standardized for 48 h (submaximal training; predominantly carbohydrate intake). CPET was performed in 3-min stages (6.5 km·h⁻¹ start; +0.7 km·h⁻¹ per stage) and stopped at RER = 1.00 and/or blood lactate = 4.0 mmol·L⁻¹ (operational VT2). After 3 min active recovery, participants completed six 60-s high-speed bouts separated by 60-s active recovery intervals (AR1–AR6), with intensities prescribed at 120–180% of VT2-derived speed, followed by an 8-min active recovery. For each AR interval, linear regression over 0–60 s yielded slopes for VO₂, VO₂/HR, VCO₂, V̇E, VE/VO₂, VE/VCO₂, and PetCO₂. Results: VT₁ was determined at 2.29 m·s⁻¹ (VO₂ 32 mL·min⁻¹·kg⁻¹) and VT2 at 3.07 m·s⁻¹ (VO₂ 42 mL·min⁻¹·kg⁻¹). Maximal intermittent speed was 5.33 m·s⁻¹ (VO₂ 45.5 mL·min⁻¹·kg⁻¹; RER 1.06; PetCO₂ 38 mmHg). VO₂ differed across successive bouts (p = 0.0001), while PetCO₂ showed a small downward drift across repetitions. Peak indices (max speed, VE/VCO₂max, PetCO₂max, VEmax) were associated with phase-specific recovery slopes across early, mid, and late recovery periods (false discovery rate–adjusted correlations). Lactate decreased over 8 min, but lactate change rates were not associated with peak indices. Conclusions: The VT₂-referenced progressive–intermittent protocol appears feasible in basketball players and provides phase-dependent recovery information that complements conventional peak CPET outcomes, with potential relevance for applied team settings. Full article

The global population explosion and accelerated industrialization have led to an increasing shortage of fossil fuels and environmental contamination, underscoring the urgent need to develop innovative energy storage technologies to improve energy utilization efficiency. As pivotal components in thermal energy storage (TES) systems, phase change materials (PCMs) enable spatiotemporal matching between thermal energy supply and demand through latent heat absorption and release during phase transitions. Organic PCMs are considered ideal candidates for thermal energy storage due to their high energy storage density, stable phase transition temperature, low supercooling, and negligible phase separation. However, inherent drawbacks such as low thermal conductivity, liquid leakage, limited light absorption, and lack of functionality have hindered their widespread application in advanced thermal management systems. Herein, we systematically summarize cutting-edge functionalization strategies for PCMs, progressing from conventional methods like thermal conductive particle blending and microencapsulation to the emerging design of 3D porous thermally conductive skeletons, including metal foams, boron nitride aerogels, carbon-based aerogels, and MXene aerogels. These frameworks not only enhance thermal transport via continuous conductive pathways and impart shape stability through capillary encapsulation but also, when integrated with photo-thermal, electro-thermal, and magneto-thermal conversion properties, enable broad applications in solar photo-thermal/photo-thermo-electric conversion, thermal management of electronics and batteries, building efficiency, and wearable thermal regulation. The review further addresses current challenges and future directions, highlighting scalable 3D framework fabrication, the shift to active thermal management, and innovative applications beyond conventional domains. By establishing a microstructure–property–application correlation, this work provides valuable insights for developing next-generation high-performance multifunctional phase change composites. Full article

An inhomogeneous thin internal stratum sometimes exists between two dissimilar materials, which is usually caused by non-uniform thermal distribution, interaction of different media, diffusion impurity or material degeneration and damage. In this paper, it is considered as a functional graded (FG) piezoelectric material in surface acoustic wave devices, and we investigate its effect on Love wave propagation within the framework of the linear piezoelectric theory. Correspondingly, the power series technique is presented and applied to solve the dynamic governing equations, i.e., two-dimensional partial differential equations with variable coefficients, with the convergence and correctness being proved. In this method, the material coefficients can change in random functions along the thickness direction, which reveals the generality of this method to some extent. As the numerical case, the elastic coefficient, piezoelectric coefficient, dielectric permittivity, and mass density change in the linear form but with different graded parameters, and the influence of material inhomogeneity on the Love wave propagation is systematically investigated, including the phase velocity, electromechanical coupling factor, and displacement distribution. In addition, the FG piezoelectric material caused by piezoelectric damage and material bonding is discussed. Numerical results demonstrated that both piezoelectric damaged and material bonding can make the higher modes appear earlier for the electrically open case, decrease the initial phase velocity, and limit the existing region of the fundamental Love mode for the electrically shorted case. The qualitative conclusions and quantitative results can provide a theoretical guide for the structural design of surface wave devices and sensors. Full article

Magnetic and structural transitions can interact significantly, leading to an enhanced magnetocaloric effect (MCE), also known as the giant or colossal effect. In this study, we investigate how subtle microstructural changes impact the magnetocaloric behavior of a MnCoGeB_0.02 alloy fabricated via suction casting. We obtained conical samples and analyzed them to understand their structure and magnetic properties. X-ray diffraction patterns revealed a coexistence of a metastable high-temperature hexagonal phase and a stable low-temperature orthorhombic phase in different regions of each cone. The presence and proportion of these phases determine the degree of magneto-structural coupling, which in turn influences the MCE. The magnetic entropy change (|ΔS_Peak|) varied notably among the samples, ranging from 12.3 to 6 Jkg⁻¹K⁻¹ under a magnetic field change of Δµ₀H = 5.0 T. These findings demonstrate that even minor microstructural changes caused by differences in solidification during suction casting can lead to noticeable variations in magnetocaloric performance. Understanding and controlling these microstructural details is vital for optimizing the functional behavior of MnCoGe-based materials. Full article