Search Results (18,684)

This study aimed to clarify how molecular structure regulates the dissolution and transient gel-layer behavior of polyacrylamide-based dry-powder drag reducers for slickwater fracturing. In the Materials Studio 2020 software, molecular dynamics simulations were performed on five representative homopolymers, including: polyacrylamide (PAM), polyacrylic acid (PAA), poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS), poly(N-vinylpyrrolidone) (PNVP), and poly [2-(acryloyloxy)ethyl]trimethylammonium chloride (PDAC). The results show that in pure water, PAA exhibits the strongest thermodynamic driving force with an interaction energy of −1005.5 kcal/mol and the lowest solvation free energy of −373.289 kcal/mol. Quantitative correlation analysis established that solvation energy and hydrogen bond density are primary predictors of macroscopic performance, yielding a correlation coefficient of R² > 0.94. Experiments confirm that optimized AM/AA (7:3) and AM/AMPS (5:5) anionic copolymers achieve stable viscosity within 120 ± 5 s and 160 ± 8 s, respectively, representing a 60% reduction in dissolution time compared to conventional industrial PAM homopolymers. The polarity, charge density, and chain flexibility of functional groups jointly regulate polymer dissolution behavior. Anionic groups significantly improve dissolution performance by enhancing intramolecular electrostatic repulsion and hydration. Full article

Triboelectric nanogenerators (TENGs) offer a promising route for self-powered microscale energy harvesting, yet their design optimisation remains empirically challenging due to the complex interplay of material surface physics, device geometry and operating mode. In this work, we present an integrated framework that combines atomic force microscopy (AFM) characterisation, COMSOL Multiphysics 6.0 finite element simulation and physics-informed conditional variational autoencoder (cVAE) to predict and optimise TENG output performance. Four polymer dielectric materials, HDPE, LDPE, TPU, and PMMA, were characterised via Kelvin Probe Force microscopy (KPFM) for work function, surface potential and surface roughness. Surface charge density was calculated from measured KPFM potential using the parallel plate capacitor model and used as a boundary condition in COMSOL Multiphysics simulations for contact-separation and lateral sliding TENG mode for dielectric film thicknesses of 50 µm and 100 µm. The simulated open circuit voltage (Voc) and short circuit charge (Qsc) across gap distances up to 150 mm formed the training dataset for a cVAE model with eight physicochemical condition features. The trained model demonstrated strong reconstruction accuracy (R² ≥ 0.94) and enables generative prediction across unseen design spaces. Results reveal that the LDPE/TPU pair at 50 µm thickness consistently achieves the highest electric outputs in both modes, and the sliding mode yields 25–30% higher voltages than the contact separation mode across all material pairs. This study provides a transferable data-efficient methodology for accelerating TENG material and geometry optimisation. Full article

The optimization of impact localization in 3D-printed structures is critical for their application in smart monitoring and damage detection systems. This study investigates the influence of infill density on the accuracy of low-velocity impact localization in 3D-printed plates. Specimens with cubic infill patterns and varying densities (30%, 50%, and 100%) were fabricated and subjected to impacts with varying locations and magnitudes using two different sensor network configurations. A genetic algorithm integrated with continuous wavelet transform was employed to simultaneously determine impact coordinates and group velocity. Key findings reveal that lower infill structures act as mechanical low-pass filters, producing clean and low-frequency signals, while higher densities support complex wave propagation with higher energy and broader frequency content. The dominant frequency of first arrival shifts toward lower values with increasing impact energy across all densities. Group velocity increases with both impact energy and infill density. For 30% infill, it averages around 450 m/s, while for 100% infill it exceeds 800 m/s. The genetic algorithm demonstrated robust performance across all experimental conditions, simultaneously estimating impact coordinates and group velocity with average errors below 6% for all infill densities. Spatial probability mass functions revealed tightly clustered predictions around true impact locations, with maximum probabilities reaching 68% and uncertainties below 5%. Computational efficiency varied modestly with infill density. These findings provide quantitative relationships between infill density, wave propagation characteristics, and localization performance for designing a reliable structural health monitoring of additively manufactured structures. Full article

GPU-accelerated quantum chemistry programs can dramatically reduce the time required for electronic structure calculations, yet most existing implementations either retrofit GPU kernels onto legacy CPU codebases or optimize individual kernels without addressing workflow-level integration overhead. We present GANSU (GPU Accelerated Numerical Simulation Utility), an open-source quantum chemistry framework written entirely in CUDA/C++ that integrates GPU-accelerated kernels for electron repulsion integrals, Fock matrix construction, and post-Hartree–Fock (post-HF) methods into a unified, GPU-resident execution pipeline. The key design principle is to eliminate host–device data transfers between computational stages by keeping all intermediate data, including density matrices, integral buffers, and Fock matrix replicas, on the GPU throughout the self-consistent field (SCF) iteration, combined with runtime-selectable integral strategies (stored ERI, resolution-of-the-identity, and Direct-SCF) that adapt to system size and available memory. On an NVIDIA H200 GPU, GANSU achieves end-to-end speedups of up to $52\times$ over PySCF for SCF, $45\times$ for MP2 on molecules with up to 470 basis functions, and $44\times$ for FCI, while outperforming GPU4PySCF by up to $34\times$ for FCI, across a range of molecular systems with up to 650 basis functions. The framework further provides analytical energy gradients and geometry optimization with nine algorithms, all operating within the same GPU-resident data flow. These results demonstrate that workflow-aware kernel integration, not just kernel-level optimization, is essential for realizing the full potential of GPU acceleration in scientific computing. GANSU is publicly available under the BSD-3-Clause license. Full article

Smart insoles equipped with pressure sensor matrices are increasingly used for gait analysis, yet high-density arrays compromise battery life and data throughput. This study aims to identify the optimal sparse sensor layout required to accurately estimate the Center of Pressure (CoP) by analyzing the trade-off between sensor number, spatial placement, and reconstruction error. Plantar pressure data were collected from twelve healthy participants walking at a self-selected speed using 16-sensor connected insoles. A combinatorial algorithm evaluated all $2^{16}-1$ possible sensor combinations to minimize the Root Mean Square Error (RMSE) in the antero-posterior, medio-lateral, and global Euclidean directions. Results reveal a non-linear convergence of accuracy that depends on the spatial axis. For longitudinal and global progression, a clear inflection point achieving sub-centimetric accuracy (RMSE < 5 mm) is reached at seven sensors. In contrast, medio-lateral tracking shows its largest discrete error reduction at five sensors, followed by gradual improvements at higher densities. Anatomical frequency analysis highlights distinct spatial requirements: the posterior heel is consistently selected for medio-lateral accuracy, while the lateral arch and metatarsal regions are critical for longitudinal progression. These findings suggest that while a minimum of seven strategically placed sensors enables robust CoP tracking across all spatial axes, optimal hardware design should remain task-specific. This work provides a data-driven framework for the development of energy-efficient wearable gait monitoring systems. Full article

The construction sector consumes significant amounts of natural resources and contributes substantially to global CO₂ emissions, making it necessary to develop materials with a reduced environmental impact. In this context, the valorization of reusable industrial waste as secondary raw materials represents a strategic direction for applying circular economy principles and for decarbonizing the construction materials industry. The scientific problem addressed in this review is the urgent need to develop construction materials with a reduced environmental footprint, given that the construction sector is a major consumer of natural resources and a significant contributor to global CO₂ emissions. This challenge requires the identification and critical evaluation of sustainable solutions that support decarbonization and the transition toward a circular economy. The main findings indicate that the valorization of industrial waste offers high decarbonization potential: supplementary cementitious materials (SCMs), such as ground granulated blast furnace slag and fly ash, can reduce CO₂ emissions by approximately 20–50%, while alkali-activated binders and geopolymers achieve reductions of 40–80% compared to Portland cement. These materials also enhance durability, extending service life by 10–20% in aggressive environments, although early-age strength may decrease by 10–30%; recycled aggregates derived from construction and demolition waste (CDW) can substitute up to 100% of natural aggregates, while rubber fibers can increase impact resistance by 30–50% and reduce density by 10–20%. However, key limitations relate to waste variability, heavy metal leaching risks (requiring immobilization efficiencies > 90%), and the relatively low technological maturity of many solutions (TRL < 7), leading to the TRL–CO₂ paradox and highlighting the need for standardization and performance-based regulatory frameworks. The synthesized results indicate that the appropriate integration of industrial waste enables a significant reduction in clinker content, lowers associated CO₂ emissions, and decreases primary energy consumption while maintaining physical–mechanical properties and durability characteristics comparable to or in some cases superior to those of traditional materials, if mix design is based on clear performance criteria, stratified according to the type of waste, dosage used, curing regime, binder chemistry, and the target application. Full article

6063 aluminum alloy has broad application prospects in aerospace and microelectronic thermal management systems due to its good thermal conductivity and moderate strength. However, its extremely high hot cracking susceptibility during the laser powder bed fusion (LPBF) process limits the direct manufacturing of complex components. This study proposes a strategy combining material composition modification with advanced structural design. By introducing TiH₂ nanoparticles (1.0~4.5 wt.%) to modify the 6063 aluminum alloy powder, Diamond-type porous structures based on triply periodic minimal surfaces (TPMS) were successfully fabricated using LPBF technology. The results show that the introduction of TiH₂ significantly suppresses the solidification cracking of the aluminum alloy. The underlying mechanism is that the L1₂-structured Al₃Ti particles, generated by the in situ decomposition of TiH₂ in the melt pool, provide high-density heterogeneous nucleation sites. This leads to a drastic decrease in the average grain size from 30.46 μm to 0.75 μm (a reduction of 97.5%), achieving a remarkable columnar-to-equiaxed transition (CET). In terms of mechanical properties, the 3.0 wt.% TiH₂ addition group exhibits excellent plateau stress (28.5 MPa) and energy absorption capacity, which is mainly attributed to the synergistic effect of fine-grain strengthening and Orowan dispersion strengthening. Thermal tests reveal that the thermal conductivity of the 3.0 wt.% group reaches 123 W/(m·K) at 100 °C. The healing of cracks reconstructs the macroscopic heat conduction paths, resulting in a significant improvement in thermal conductivity compared with the unmodified group. This work provides a theoretical reference for the development of high-performance, crack-free, and multi-functional integrated aluminum alloy components via additive manufacturing. Full article

Despite the many advantages of renewable energy sources, the stochastic nature of their generation creates a mismatch between electricity production and demand timing. Without appropriate storage solutions, surplus energy remains unused. Although battery energy storage systems are increasingly applied to improve the flexibility and reliability of power systems, there is still a research gap in forecasting the optimal power and storage capacity of solar power plant–battery energy storage system energy complexes operating in parallel with the grid under short-term forecasting conditions, particularly when economic aspects such as partial leasing of storage capacity are considered. Therefore, the development of energy complexes based on solar power plants with the integration of battery energy storage systems, as well as the development of corresponding computational models, becomes critical for ensuring the stability, flexibility, reliability, and efficiency of power systems. Battery energy storage systems are widely used due to their availability, high response speed, significant energy density, and sufficient power capacity; however, their cost remains relatively high. This paper proposes a methodology and a calculation model for determining the optimal forecasted capacity and the rational storage requirements of an energy complex consisting of a solar power plant and a battery energy storage system operating in parallel with the grid at constant power under short-term forecasting conditions (day-ahead or longer). The proposed approach makes it possible to minimise the costs of energy companies associated with the short-term lease of part of a battery energy storage system when they do not own one, or, if such a system is available, to lease out its unused capacity and obtain corresponding profits. The validation of the computational model uses a dataset of hourly daily power outputs of solar power plants in the Integrated Power System of Ukraine for 2018. Statistical analysis of the obtained results shows that the probability of occurrence of maximum deviations for the optimal capacity of the energy complex (5.4%), as well as for the power and capacity of the battery energy storage system (13% and 18%, respectively), does not exceed 0.05 during the year. The results confirm that the proposed methodology provides a reliable basis for determining optimal parameters of solar power plant–battery energy storage system energy complexes and enables economically efficient use of storage capacity through short-term leasing mechanisms. Although the proposed methodology is applied using solar power plant generation data for the national power system as a whole, it can also be used for individual solar power plants located in different regions and countries with different climatic conditions. Certainly, the calculated coefficients differ, but the methodology itself and the sequence of its application remain the same. Full article

Textile wastewater contains recalcitrant dyes and organic matter, requiring efficient, scalable treatment technologies. This study optimized an aluminum-based electrocoagulation (EC) process to maximize color removal (Y₁) and chemical oxygen demand (COD) reduction (Y₂) using synthetic textile wastewater (SWW), and evaluated the practical transferability of the optimized conditions using real textile wastewater (RTW). A rotatable central composite design (CCD) coupled with response surface methodology (RSM) was used to assess the effects of treatment time, NaCl concentration, and applied voltage on both responses. From a modeling perspective, the results reveal the coexistence of symmetric and asymmetric response behaviors; quadratic effects define locally symmetric regions around the optimum, while interaction terms introduce asymmetry due to coupled electrochemical phenomena. Under the optimized conditions (16.5 min, 2.9 g·L⁻¹ NaCl, 18 V), removal efficiencies reached 99% for color and 97% for COD reduction, with a specific energy consumption of 6.6 kWh·m⁻³ and sludge moisture content of 92–94%. To assess applicability beyond bench scale, the optimized voltage, current, and electrolyte concentration were applied to a 50 L batch of RTW collected from the final rinsing stage of a denim dyeing process. Treatment time was extended to 84 min to compensate for the lower current density at the larger scale; under these conditions, 95% color removal and 80% COD reduction were achieved. Full article

With the strategic shift toward reducing reliance on critical raw materials, Cobalt-free eutectic high-entropy alloys (EHEAs) have emerged as a pivotal frontier for high-performance structural applications. This review systematically elucidates the synergistic relationship between Co-free alloy design and the non-equilibrium solidification mechanisms of Selective Laser Melting (SLM). The ultra-high cooling rates (10⁵–10⁸ K/s) inherent in SLM are shown to refine eutectic lamellae to the sub-micron scale (typically <300 nm), effectively suppressing the macro-segregation common in conventional casting. We evaluate the design principles of Al-Cr-Fe-Ni and related systems, noting that SLM-processed Co-free EHEAs frequently achieve yield strengths exceeding 1000 MPa and ultimate tensile strengths (UTSs) surpassing 1300 MPa, while maintaining tensile elongations above 10%—a significant improvement over the coarse-grained structures produced by traditional methods. Furthermore, the study identifies critical processing windows, such as laser energy densities (60–120 J/mm³), required to mitigate micro-cracking and achieve near-full density (>99.5%). By synthesizing recent experimental breakthroughs and AI-driven modeling, this review provides a quantitative roadmap for the precision manufacturing of cost-effective, high-performance EHEAs, bridging the gap between theoretical alloy design and industrial additive manufacturing. Full article

Mobile thermal energy storage (M-TES) demonstrates significant commercialization potential in industrial waste heat recovery, distributed heating, and clean heating applications, which is primarily based on three technical pathways: sensible heat storage, latent heat storage using phase change materials (PCMs), and thermochemical heat storage. The updated status of M-TES, mainly on PCMs and thermochemical ones, and the challenges facing application were reviewed, and potential development trends were discussed in the present study. Sensible heat storage is relatively mature and cost-effective; however, it suffers from low energy density and comparatively high heat loss during storage and transport. Latent heat storage utilizes the phase transition enthalpy of PCMs to store thermal energy, offering higher energy density and near-isothermal heat release, making it a focal point of current academic and industrial research. Nevertheless, latent heat storage still faces technical bottlenecks, including low thermal conductivity, phase separation, and supercooling of PCMs. Thermochemical heat storage relies on reversible chemical reactions to convert and store thermal energy as chemical energy, theoretically achieving the highest energy density and minimal heat loss. However, due to its technical complexity and high system cost, thermochemical storage remains largely in the early stages of research and demonstration. Overall, as a bridge between heat supply and demand, the development trend emphasizes the design of high-performance composite PCMs, enhanced system integration, and intelligent operational management. However, its large-scale deployment is still constrained by challenges related to energy density, heat transfer enhancement, long-term material stability, and techno-economic feasibility. Full article

This paper proposes a low weight hybrid battery–supercapacitor energy storage system interfaced with bidirectional DC/DC converters with high power/current capability for aircraft applications. The supercapacitor converter having high power uses two pairs of interleaved coupled inductors to reduce the overall current ripple whilst increasing the converter’s power density. Due to the sensitive performance to saturation of the coupled inductors, a phase current balancing strategy is proposed to counter the effect current imbalance in the channels that would cause saturation degrading overall performance. A power management strategy (PMS) is implemented along with a low pass filter to separate the supercapacitor high frequency power component reference from the battery low frequency power component; therefore, separating the energy and power requirement for the energy storage system contributing to minimizing its weight whilst ensuring the current/power stresses are correctly handled. The validity of the system design is validated by a series of transient tests is conducted both in a simulation model as well as experimentally. Full article

During the marine transport of liquid hydrogen, heat ingress leads to the generation of boil-off gas (BOG), which increases the pressure in the liquid hydrogen storage tanks. Effective BOG management is therefore essential to ensure tank safety and minimize hydrogen loss. This study develops a cryogenic compression recovery and storage system for BOG generated during the marine transport of 160,000 m³ liquid hydrogen. The core process involves compressing a portion of the BOG and subsequently utilizing the BOG’s inherent cold energy to cool the compressed hydrogen, ultimately enabling the storage of the final cryogenic compressed hydrogen product. ASPEN-PLUS software was employed to analyze the proposed system’s specific energy consumption (SEC) and ψ (hydrogen density/SEC) for producing cryogenic compressed hydrogen (CcH₂) across a temperature range of 53 to 110 K and a pressure range of 40 to 100 MPa. Seven optimal sets of state parameters were identified for the cryogenic compressed hydrogen product. Based on a specified optimal parameter set of 80 K and 50 MPa, a simulation of the proposed system’s performance yielded a SEC of 2.25 kWh/kg CcH₂ and an exergy efficiency of 87.88% with BOG feed at 53 K and 0.1 MPa, along with the exergy loss and exergy efficiency for each component. Compared to a BOG re-liquefaction system and a MRJT CcH₂ system under identical conditions, the proposed system achieves 31.81% and 64.9% reduction, respectively, in SEC and 17.32% and 94.6% improvement, respectively, in exergy efficiency. Furthermore, the effects of feed temperature and cryogenic compressed hydrogen product mass flow rate on the proposed system’s SEC and exergy efficiency were investigated. Full article

Silicon carbide (SiC) power devices are emerging as an alternative for electrical transportation systems to improve energy efficiency, reduce carbon emissions, increase power density, and enable long-term cost savings throughout the product life cycle. Thus, a fair comparison with state-of-the-art Silicon (Si) technology is required to justify the productization of SiC devices. This work performs a systematic investigation of both technologies at the device and system levels for distinct power module voltage classes (3.3 and 6.5 kV) and circuit topologies. Initially, experimental characterization of state-of-the-art power modules is performed, followed by energy efficiency characterizations at the power converter level. Then, an electrothermal simulation model was built and validated based on experimental results. Accurate system simulations of commercial two- and three-level traction topologies were developed, focusing on efficiency over the entire load range, loadability, potential energy savings under realistic train drive cycles, and a financial comparison of inverter prices per kW. SiC exhibits lower loadability degradation at high switching frequencies (>500 Hz) than Si technology. Energy-saving potentials of 40–70% in the traction inverter with a guaranteed return on investment during the converter’s lifetime are achieved by substituting Si with SiC inverters. In addition, massive energy savings of up to 200 MWh per inverter lifetime can effectively reduce the carbon footprint of railway systems (up to ~76 t CO₂-eq saved during the inverter lifetime). This paper provides essential information for distinct stakeholders to support the decision-making process and design considerations for future railway power conversion technologies. Full article

The global energy transition to sustainable renewable energy sources has caused a growing demand for advanced energy storage systems, particularly sensible thermal energy storage systems because of their low cost and high performance. This work experimentally investigates the potential use of South African ferroalloy slags as filler materials in packed bed configurations. Ferrochrome and silicomanganese slags are characterised and used as filler materials, and air is used as the heat transfer fluid. The experiments are designed for high-temperature systems, with working temperatures of up to 600 °C and usable energy limited to 400 °C. The slags’ thermophysical properties are evaluated and used to assess their performance during thermal cycling. Material phase composition, grain size, and porosity distributions are analysed with automatic scanning electron microscopy. Thermogravimetric analysis is done to study the chemical stability of the slags at temperatures reaching up to 1000 °C. The slags’ thermophysical properties and thermal energy storage capacities are comparable to other candidate filler materials for high thermal energy storage systems. High thermal energy storage efficiencies of 70–90% are achieved in the experiments. However, a high pressure drop of up to 2 bar is recorded. The slags are found to be chemically stable for use in systems with working temperatures of up to 1000 °C. Volumetric energy densities of 165–187 kWh/m³ are recorded during thermal energy recoveries at temperatures above 400 °C. The slags were found to be suitable for use as filler materials in sensible energy storage systems with working temperatures of up to 1000 °C. Full article