Search Results (1,562)

Computational fluid dynamics (CFD)-driven optimization of engineering systems is often constrained by high computational cost, particularly when surrogate models must be constructed from limited simulation samples. Although surrogate-assisted multi-objective optimization can substantially reduce CFD evaluations, local prediction errors in decision-sensitive Pareto regions may alter feasibility classification and engineering recommendations near active constraints. To address this issue, this study proposes a Pareto-active-region-guided sequential surrogate modeling framework (PAR-SSM) for multi-objective optimization of liquid-cooled battery thermal management systems. Starting from 15 face-centered central composite design (FCCD) samples, the framework selectively introduces additional high-fidelity CFD evaluations into Pareto-active and constraint-sensitive regions, yielding a 21-sample refined surrogate model. Rather than uniformly improving global prediction accuracy, PAR-SSM directs the limited CFD budget toward regions where surrogate errors can directly influence engineering decisions. After model freezing, three independent Fluent cases were used exclusively for validation, yielding mean absolute deviations of 0.098 °C for maximum temperature and 0.341 °C for temperature difference, while also revealing residual feasibility risk near active constraint boundaries. Application to an autonomous underwater vehicle (AUV) battery module showed that the N = 3 configuration dominated the nominally constrained Pareto set and provided a favorable thermal–hydraulic trade-off under low auxiliary energy consumption. Overall, PAR-SSM provides a decision-oriented strategy for balancing computational cost and optimization credibility in CFD-intensive, constrained multi-objective design. Full article

This study investigates the heat transfer and fluid flow characteristics of six triply periodic minimal surface (TPMS) structures, specifically Gyroid (G3P6, G3P7, G3P8, G1P7) and Diamond (D1P7 and D3P7) configurations, using both experimental and numerical methods. Comparative analysis was conducted to evaluate the impact of adding a base to these structures on their thermal and hydraulic performance. The TPMS structures were assessed in terms of measured surface temperature, convection heat transfer coefficient, Nusselt number, overall thermal resistance, pressure drop, friction factor, and overall thermal–hydraulic performance. Results indicate that base-free structures exhibit better heat dissipation, with surface temperatures increasing by 1.2 °C (G3P6) to 5.5 °C (D3P7) when the base is added. The addition of the base reduces the convection heat transfer coefficient on average by 3.9% (G3P6) to 23% (D1P7) and increases overall thermal resistance by 3.1% (G3P6) to 28.7% (D1P7). The friction factor also rises by 6.1% (D1P7) to 47.3% (G3P6) due to the addition of the base. When the base is added, the overall thermal–hydraulic performance declines by 8.5% (G3P7) to 33.6% (D3P7), with Diamond structures experiencing a more significant reduction compared to Gyroid structures. Among the Gyroid structures, G3P6 (lower cell size and 60% porosity) demonstrated the lowest surface temperature and the highest heat dissipation capacity, while G3P8 (80% porosity) exhibited the lowest thermal performance. The Gyroid structure with larger cell size (G1P7) achieved the highest overall thermal–hydraulic performance, effectively balancing heat dissipation and fluid resistance. In contrast, when the base is integrated, the Gyroid structure with a smaller cell size and lower porosity (G3P6) showed the lowest overall thermal–hydraulic performance. Full article

Engine-inlet fuel pressure in helicopters can fluctuate during flight manoeuvres because load-factor variation changes both fuel distribution in the tanks and the pressure balance along the fuel-supply pipeline. This simulation-only study investigates a passive pressure-regulation scheme based on a constant-pressure reducing valve (CPRV) for a representative five-tank helicopter fuel system. Mathematical models of the fuel tank, booster pump, jet pump, check valve, fuel-supply pipeline, and CPRV are integrated in AMESim and checked against reported tank-depletion data, fuel-centre-of-gravity data, and code-to-code benchmark results. A controlled same-model isolation check additionally compares a mobile CPRV spool with the same spool constrained at its fully open end stop while all pump, tank, line, demand, load, fluid, reference-pressure, and solver settings remain unchanged. In a longitudinal load-factor ramp to 1 g, the mobile-spool model maintains 1.8042–1.8047 barA, whereas the locked-open control gives 2.4287–2.5917 barA. Across the principal regulated simulations, the maximum absolute deviation from the 1.8 barA target is approximately 0.005 bar. These values are numerical results for the stated model and must not be interpreted as sensor-resolvable hardware accuracy or qualification evidence. Full article

Solar tracking can increase photovoltaic (PV) energy yield, but its contribution to sustainable electricity depends on more than geometric gain. This structured narrative review evaluates flat-plate and low-concentration PV trackers using an integrated three-layer taxonomy covering mechanical architecture, actuation and drivetrain, and control strategy. Tracker classes are compared in terms of annual energy gain, life-cycle cost, parasitic consumption, land-use efficiency, structural resilience, reliability, maintainability, and deployment maturity. Utility-scale horizontal single-axis trackers using astronomical control, backtracking, supervisory monitoring, and weather-dependent stow provide the most mature balance of energy yield, cost, and operational robustness. Dual-axis systems can offer higher output under high-direct-normal-irradiance conditions but impose greater structural and O&M burdens, while passive fluid-based and shape-memory-alloy concepts remain mainly experimental. The review also examines bifacial and terrain-aware tracking, agrivoltaic dual land use, extreme-weather resilience, tracker-specific availability, artificial intelligence, digital twins, predictive maintenance, and end-of-life considerations. A plant-level decision framework and reporting checklist are proposed to support transparent, project-specific choices that maximize lifetime renewable-energy value while limiting material use, land-use conflict, operational risk, and avoidable life-cycle impacts. Full article

Thermal runaway of lithium-ion batteries involves rapid heat release, gas generation, and multiphase transport, but their interaction inside a cell remains difficult to resolve. A multiscale computational fluid dynamics model was developed for a single 18650 cell by coupling microscale reaction kinetics, mesoscale interfacial heat transfer, and macroscale gas–liquid transport with a stationary porous-solid energy balance. The model describes internal temperature and the evolution of carbon dioxide, oxygen, water vapour, and hydrogen fluoride while examining the effects of porosity and the modelled dimethyl carbonate mass fraction. The medium-to-fine grid difference in carbon dioxide mass fraction was approximately 0.16%. Time steps of 0.01, 0.001, and 0.0001 s produced mass fractions of 0.0564, 0.0617, and 0.0618, respectively. Increasing the solvent mass fraction and porosity primarily shortened the induction period, while the peak temperature and terminal species levels remained similar. A quadratic response surface fitted to the simulation database was searched using grey wolf, genetic, and particle swarm methods. Grey wolf and particle swarm gave candidate times to peak temperature of about 238.8 s, whereas the genetic method gave 237.2 s, a difference of 1.6 s (0.67%). Particle swarm reached the high-response region within fewer iterations, while grey wolf maintained broader exploration. The proposed model connects reaction kinetics with macroscopic temperature and species evolution and clarifies how electrolyte composition and porous structure regulate the time scale of thermal runaway. Full article

This paper presents an experimental investigation into the flow characteristics and volumetric efficiency (η_vol) of a fixed-displacement external gear pump (GHD 17R) operating under coupled hydraulic parameters using an eco-friendly synthetic ester-based hydraulic fluid (48 mm²·s⁻¹ at 40 °C). Measurements were performed on a laboratory single-circuit hydraulic test rig across a rotational speed range of 500–2500 min⁻¹, operating pressure range of 2–10 MPa, and fluid temperature range of 30–60 °C. To eliminate flow fluctuations caused by structural vibrations at 1250 and 1750 min⁻¹, a 15% trimmed mean statistical filter was successfully implemented. A comparative sensitivity analysis—evaluating absolute, normalized, and relative significance—was developed and compared against a three-way analysis of variance (ANOVA) effect size model (η² and partial η²). The relative sensitivity approach identified rotational speed as the dominant parameter for direct hydraulic flow, accounting for 95.80% of total variation. Conversely, when evaluating volumetric efficiency, the proportional impact of speed was removed, revealing a balanced distribution of internal losses: rotational speed contributed 54.73%, fluid temperature 26.08%, and pressure 19.19%. The three-way ANOVA confirmed that all primary parameters and their cross-interactions had a statistically significant effect (p < 0.05). The findings scientifically demonstrate that temperature-induced viscosity collapse exhibits a stronger relative dynamic sensitivity on volumetric losses than pressure fluctuations within standard operating envelopes. The constructed multi-dimensional flow and efficiency maps provide practical input for advanced diagnostic tools, real-time thermal condition monitoring, predictive maintenance, and energy-optimized control schemes in modern fluid power systems using eco-friendly lubricants. Full article

As the global energy sector and maritime industry transition toward carbon neutrality, Carnot batteries have emerged as a critical technology for flexible, long-duration energy management. Carnot batteries, which operate on a Power-to-Heat-to-Power principle, present a highly promising alternative to conventional electrochemical batteries. The present study provides a review of Carnot battery architectures, systematically evaluating their thermodynamic cycles, working fluids, Thermal Energy Storage media and key turbomachinery components. A comparative assessment of the current literature illustrates that system selection requires balancing round-trip efficiency, Energy Storage Density and Technology Readiness Level. According to the findings of the present study, high-temperature Brayton cycles offer robust baseline efficiencies of 60–80% whereas subcritical Rankine cycles benefit from commercial maturity and can achieve efficiencies exceeding 200% when integrated with cryogenic heat sinks like LNG. It should be clarified that efficiency values exceeding 100% represent “Apparent Round-Trip-Efficiencies (RTE)” resulting from the thermodynamic contribution of external exergy streams, such as LNG cryogenic cold, rather than standalone cycle efficiencies, which are strictly below 100%. In addition, volumetric energy density varies drastically based on the physical phase of the storage medium, scaling from under 1 kWh/m³ for unpressurized water to over 385 kWh/m³ for advanced thermochemical systems. Although most configurations currently remain in the prototyping phase, the technology holds transformative potential for the maritime sector. Carnot batteries can deliver a self-contained, zero-emission electrical power supply to cover the vessel’s electrical load requirements during harbor stays and transit within Emission Control Areas (ECAs) by dynamically capturing and storing shipboard waste heat during open sea transit. Full article

This study presents a numerical model of electromagnetic and thermal processes characteristic of a submerged arc furnace. Because direct modeling of a full-scale industrial furnace is complex and difficult to validate experimentally, a laboratory system without an electric arc is considered at this stage. The system reproduces the main features of current supply and energy distribution in the conductive region of the furnace bath. The model is implemented in ANSYS Fluent 2020 R1 using user-defined scalar equations for the electric potential, the components of the magnetic vector potential, and their time derivatives. The implementation was assessed in terms of mesh independence, time-step sensitivity, current and energy balances. The calculations yielded consistent distributions of electric potential, current density, magnetic flux density, Joule heat generation, and temperature. Heating was described using a two-stage scheme: the transient electromagnetic problem is first solved to obtain period-averaged Joule heat generation, which is then used as a source term in the energy equation. The model represents the first stage of a computational framework for submerged arc furnace modeling: at this stage, it is developed and assessed using a simplified laboratory configuration without an electric arc, while in future work it can be supplemented with an arc-channel description and extended to industrial furnace conditions. Full article

Low seawater temperatures constrain the operation of open rack vaporizers (ORVs) and intermediate fluid vaporizers (IFVs), while also increasing pumping-related emissions at LNG terminals. This study establishes a carbon-oriented framework for an expanded ORV–IFV regasification system sharing a fixed-speed seawater pump network and evaluates thermal discharge from an adjacent power plant as a supplementary heat source. Using measured LNG composition, we developed an Aspen HYSYS model based on the Peng–Robinson equation of state and steady-state energy balances, which was validated against field data. Electricity-related CO₂ emissions from seawater pumps and auxiliaries were quantified using the regional grid emission factor, while pump scheduling was formulated as a mixed-integer nonlinear programming (MINLP) problem. Model predictions differed from measurements by approximately 2%. Lower seawater temperatures increased emissions and restricted maximum regasification capacity to 80% and 57% of the design value at 3–4 °C and 2–3 °C, respectively. For LNG throughputs of 300, 500, and 700 t/h, CO₂ reduction increased with warm-seawater flow and inlet temperature; maximum reductions reached approximately 50–55% under 3–7 °C ambient seawater conditions and 40% under 6–20 °C conditions, with a 95% confidence interval of ±3.9 percentage points. Monthly discharge data indicated reductions of approximately 20% in winter and 45% in summer. Integrating power-plant waste heat with load-dependent pump scheduling can improve the carbon performance of LNG regasification. Full article

Cannabidiol (CBD) is a lipophilic phytocannabinoid of interest for dermocosmetic and topical applications, but its poor aqueous solubility and sensitivity to environmental conditions make its formulation challenging. This work aimed to develop avocado oil-in-water emulgels for CBD incorporation using a mixed emulsifying system based on Kolliphor EL and cricket protein and a commercial Aloe vera/Chondrus crispus gel as the structuring phase. First, different Kolliphor EL:cricket protein ratios were evaluated according to droplet size distribution. No significant differences in droplet size were found among formulations containing at least 67% Kolliphor EL (p > 0.05); therefore, 67K-33G was selected because it maximized the substitution of Kolliphor EL with cricket protein without significantly affecting droplet size. Progressive replacement of water by the commercial hydrocolloid gel markedly increased consistency and viscoelasticity, producing a transition from fluid emulsions to elastic emulgels between 50 AV and 75 AV. The 75 AV formulation showed low Turbiscan Stability Index values, a predominantly elastic response, and a more balanced structure than 100 AV. The selected emulgel showed a total analytical recovery of 96.2 ± 1.2% for CBD and retained 97.3 ± 0.7% of the initially recovered CBD after 30 days of storage at 4 °C protected from light. These results support the potential of Aloe vera/Chondrus crispus-based emulgels as semisolid carriers for lipophilic bioactive compounds. Full article

Deep coalbed methane (CBM) represents a strategic successor field for unconventional oil and gas exploration and development in China, and fluid mobility is a key parameter determining CBM recovery rates. Existing NMR-based studies on coal rock pore structure and fluid mobility suffer from three deficiencies: a lack of coal rock classification based on T₂ spectral morphology, failure to incorporate fractal characteristics into pore classification, and insufficient understanding of fluid mobilization mechanisms in different pore types during gas-driven recovery. This study investigates deep coal rocks of the Taiyuan Formation in the Linxing Block, eastern Ordos Basin, using low-field nuclear magnetic resonance (LF-NMR), saturation gas displacement experiments, and fractal theory. Deep coal rocks were classified into three types based on T₂ spectral peak morphology under saturated conditions: Type I (central main peak), Type II (left-shifted main peak), and Type III (balanced bimodal peak). A fractal-based method was established to subdivide fluid-filled pores into four types: P1-1, P1-2, P1-3, and P2. Through multiple nitrogen displacement experiments, the fluid mobilization characteristics of each pore type at different displacement stages were quantitatively characterized. A fluid mobility index was proposed to comprehensively evaluate the overall fluid mobility of coal rocks. The results indicate that Type I coal rocks exhibit the highest fluid mobility (54.83% after three displacement cycles), with P1-3 pores as the primary mobile fluid reservoir, whereas Type II and Type III coal rocks show lower mobility (27.70% and 32.89%, respectively), with P1-2 pores as the dominant contributors. Pore structure complexity exhibits a significant nonlinear evolutionary relationship with fluid mobility. The fluid mobility index demonstrates a strong positive correlation with the degree of mobile fluid, validating its effectiveness in characterizing fluid mobility in deep coal rock reservoirs. These findings provide a theoretical foundation for sweet spot identification and development optimization in deep coal gas reservoirs. Full article

Water atomization is widely used for producing FeSiCr alloy powder, in which melt delivery conditions strongly influence jet breakup and powder refinement. In this study, a coupled volume of fluid-discrete phase model (VOF-DPM) was established to investigate the effect of delivery tube diameter (3, 4, 5, and 6 mm) on flow characteristics, interfacial instability, and droplet evolution at a constant water pressure of 120 MPa, and the simulation results were validated by industrial trials. As the tube diameter increased from 3 to 6 mm, the melt mass flow rate rose from 0.100 to 0.368 kg/s, the primary breakup position shifted downstream from 94.6 to 236.5 mm, and the peak negative pressure along the centerline decreased from −41.12 to −31.65 kPa. The simulated average particle size increased from 9.176 to 22.791 μm, while the experimentally measured mean particle size increased from 9.0 to 19.6 μm and the fine-powder yield decreased from 43.77% to 22.28%. Although the 3 mm tube produced the finest powder, it showed a higher tendency for clogging and unstable melt delivery. Overall, the 4 mm delivery tube provided the best balance between powder refinement, size uniformity, and production stability. Full article

Background/Objectives: Adolescent sexuality is multidimensional, yet brief instruments assessing attitudes, experiences, and contextual influences from a biopsychosocial perspective remain limited. This study aimed to develop the Comprehensive Questionnaire on Attitudes, Experiences, and Contexts of Adolescent Sexuality (CIAECSA) and examine its content validity, comprehensibility, feasibility, internal consistency, and exploratory internal structure. Methods: A cross-sectional methodological study comprised three phases: theoretical delimitation and generation of 30 initial items; content evaluation by nine experts and semantic validation with 26 adolescents; and pilot administration to 51 adolescents from educational settings in Toledo, Spain. The pilot sample included 35 females (68.6%), 15 males (29.4%), and one gender-fluid participant (2.0%), aged 12–17 years (mean = 14.41; SD = 1.72). Content validity, perceived clarity, feasibility, Cronbach’s alpha, and principal component analysis with Varimax rotation were examined. Results: The final questionnaire comprised 18 items across three domains: sexuality/gender/anatomy, emotional/physical pain, and self-care/environment. The scale-level Content Validity Index (S-CVI/Ave) was 0.955, and mean perceived clarity was 4.53/5. The mean completion time was 5.52 min. Cronbach’s alpha was 0.800, 0.780, and 0.740 for the three domains and 0.715 for the total scale. The KMO was 0.659, Bartlett’s test was significant (p < 0.001), and an exploratory three-component solution, examined against the prespecified domains, explained 51.4% of the variance. Conclusions: The findings provide favorable evidence of content validity, comprehensibility, feasibility, and internal consistency. The CIAECSA may help identify educational needs and psychosocial factors related to adolescent sexuality, although its internal structure and additional measurement properties require examination in larger, balanced, and independent samples. Full article

Background: Coagulopathy in sepsis represents a dynamic continuum ranging from sepsis-induced coagulopathy (SIC) to disseminated intravascular coagulation (DIC), but its early evolution and clinical determinants remain poorly defined. Objectives: To assess the temporal dynamics of SIC and DIC and examine factors associated with their evolution during the early phases of sepsis. Methods: A prospective longitudinal observational study was conducted on 299 patients with sepsis admitted to the Intermediate Care Unit (IMCU). Patients were evaluated at admission and subsequently at 24, 48, 72, and 96 h, for a total of 1.447 observations. Clinical, laboratory, and hemodynamic data were collected at each time point, and SIC and DIC scores were calculated. The evolution of coagulopathy and its association with clinical and therapeutic variables were analyzed using appropriately adjusted generalized estimating equation (GEE) longitudinal models. Results: The prevalence of SIC increased from 36.8% at baseline to 47.5% at 24 h, and then declined to 20.8% at 96 h. DIC prevalence decreased from 21.7% to 9.7%. Coagulopathy at the previous time point was the main determinant of subsequent coagulopathy (SIC: OR 31.17; DIC: OR 67.17; p < 0.001). Incidence was highest during the early phases (SIC: 12.8% to 2.2%; DIC: 4.7% to 1.1%), whereas persistence decreased over time (SIC: 34.7% to 18.6%; DIC: 18.5% to 8.6%). Higher Sequential Organ Failure Assesment (SOFA) scores were associated with increased risk. Therapeutic anticoagulation was inversely associated with subsequent coagulopathy, including overt DIC positivity among patients without overt DIC at baseline (OR 0.059; 95% CI 0.012–0.290; p < 0.001). Higher cumulative fluid balance was associated with overt DIC in exploratory predicted-probability analyses, independent of vasopressor use, although this gradient did not reach statistical significance in adjusted models and is hypothesis-generating. Diuretic therapy was associated with an increased risk of SIC (OR 2.20; p = 0.008). Conclusions: Coagulopathy in sepsis occurs early and is strongly dependent on its initial trajectory. SIC and DIC represent stages of a continuum, with onset occurring predominantly within the first 24–48 h. The inverse association with therapeutic anticoagulation is hypothesis-generating and should not be interpreted as a treatment effect. Full article

The spontaneous emergence of macroscopic order in driven, far-from-equilibrium complex fluids lacks a generalized framework capable of bridging continuous and discrete symmetry-breaking transitions. In this study, we propose a non-equilibrium phenomenological framework that synthesizes irreversible thermodynamics, coupled Landau–de Gennes potential expansions, and active hydrodynamics. The formulation employs a single tensorial order parameter, a nonlinear state-dependent jamming mobility closure, and a generalized set of dimensionless groups to map the non-equilibrium phase space. The model predicts a sequential symmetry-breaking cascade and reproduces the emergence of polar heliconical smectic and antiferroelectric phases in driven liquid crystals, as well as the transition from isotropic active gases to macroscopic fluid flocks and active Wigner crystals in purely repulsive Janus colloids. Across these systems, a dimensionless active torque number acts as the principal bifurcation parameter, suggesting that their macroscopic structural transitions are governed by a common balance between thermodynamic and kinematic effects rather than by the details of their microscopic interactions. Full article