Search Results (1,701)

Supercritical carbon dioxide (SC-CO₂) power cycles offer a promising solution for offshore platforms’ gas turbine waste heat recovery due to their compact design and high thermal efficiency. This study proposes a novel parallel-preheating recuperated Brayton cycle (PBC) using SC-CO₂ for waste heat recovery on offshore gas turbines. An integrated energy, exergy, and economic (3E) model was developed and showed good predictive accuracy (deviations < 3%). The comparative analysis indicates that the PBC significantly outperforms the simple recuperated Brayton cycle (SBC). Under 100% load conditions, the PBC achieves a net power output of 4.55 MW, while the SBC reaches 3.28 MW, representing a power output increase of approximately 27.9%. In terms of thermal efficiency, the PBC reaches 36.7%, compared to 21.5% for the SBC, marking an improvement of about 41.4%. Additionally, the electricity generation cost of the PBC is 0.391 CNY/kWh, whereas that of the SBC is 0.43 CNY/kWh, corresponding to a cost reduction of approximately 21.23%. Even at 30% gas turbine load, the PBC maintains high thermoelectric and exergy efficiencies of 30.54% and 35.43%, respectively, despite a 50.8% reduction in net power from full load. The results demonstrate that the integrated preheater effectively recovers residual flue gas heat, enhancing overall performance. To meet the spatial constraints of offshore platforms, we maintained a pinch-point temperature difference of approximately 20 K in both the preheater and heater by adjusting the flow split ratio. This approach ensures a compact system layout while balancing cycle thermal efficiency with economic viability. This study offers valuable insights into the PBC’s variable-load performance and provides theoretical guidance for its practical optimization in engineering applications. Full article

This study presents the first computational investigation of hybrid propeller configurations that combine toroidal and conventional blade geometries. Using Delayed Detached Eddy Simulation (DDES) with the Shear Stress Transport (SST) $k-\omega$ model for flow analysis and the Ffowcs Williams and Hawkings (FW–H) formulation for aeroacoustic prediction, five hybrid propeller designs were evaluated: a baseline model and four variants with modified loop-element spacing. The results show that the V-Gap-S configuration achieves the highest figure of merit (FM), producing over 10% improvement in propeller performance relative to the baseline, while also exhibiting the lowest turbulence kinetic energy (TKE) levels across multiple radial planes. Aeroacoustic analysis reveals quadrupole-like directivity for primary tonal noise, primarily driven by blade tip–vortex interactions, with primary tonal noise strongly correlated with thrust. Broadband noise and overall sound pressure level (OASPL) exhibited dipole-like patterns, influenced by propeller torque and FM, respectively. Comparisons of surface pressure, vorticity, and time derivatives of acoustic pressure further elucidate the mechanisms linking blade spacing to aerodynamic loading and noise generation. The results demonstrate that aerodynamic performance and aeroacoustics are strongly coupled and that meaningful noise reduction claims require performance conditions to be matched. Full article

Large-diameter butterfly valves are essential control components in high-flow hydraulic systems, where blade geometry directly impacts operational reliability, energy efficiency, and lifecycle cost. This study presents an integrated structural–hydraulic optimization of a DN3000 Boving butterfly valve blade rated for a maximum operating pressure of 10 bar with comparative analysis of a conventional flat blade and an optimized curved blade. The work applies a CFD–FEM framework specifically to DN3000 Southern African valves, which is rare in the literature. Numerical simulations evaluated stress distribution, deformation, pressure losses, and flow stability under design and hydrostatic test conditions. The curved blade achieved a 58.6% reduction in peak von Mises stress, a 50% reduction in weight, a 22% reduction in load loss, and a 33% reduction in actuation torque requirements, while maintaining seal integrity. Cost analysis revealed a 50% reduction in material costs and simplification of manufacturing. The results confirm that the introduction of curvature significantly improves structural strength and hydraulic efficiency, thus providing a reproducible framework for the design of lighter and more economical valves in hydropower, municipal and industrial applications. Full article

This study focuses on the design, material selection, and wind-induced fatigue analysis of a dynamic movable sculpture atop the Welcome Tower at Yazhou Bay Bougainvillea Park in Sanya. The sculpture, consisting of eight movable leaves, is driven by a hydraulic system enabling it to assume five distinct shapes. Nickel-saving stainless steel (S22152/S32001) was chosen as the primary material due to its excellent corrosion resistance and strength, ensuring durability in the harsh coastal environment. The mechanical system is designed with a two-level lifting device, rotation system, and push-rod mechanism, allowing the leaves to perform functions such as rising, opening, closing, and rotating while minimizing mechanical load. Wind tunnel tests and numerical simulations were conducted to analyze the sculpture’s performance under wind loads. Using the rain-flow counting method and Miner’s linear fatigue accumulation theory, the study calculated stress amplitude and fatigue damage, finding that the most unfavorable fatigue life of the sculpture’s components is 380 years. This analysis demonstrates that the sculpture will not experience fatigue damage over its expected lifespan, providing valuable insights for the design of dynamic sculptures in coastal environments. The research integrates mechanical design, material selection, and fatigue analysis, ensuring the sculpture’s long-term stability and resistance to wind-induced fatigue. Full article

Debris accumulation critically impacts hydraulic structures by altering approach flow, amplifying hydrodynamic forces, and inducing backwater rise. While previous research has extensively examined drag forces due to debris, the effects of debris porosity, its proximity to the channel bed, and upstream–downstream water level difference on hydrodynamic loadings are still not fully understood. To address these gaps, 336 experiments were conducted under subcritical flow conditions, involving nine debris configurations, characterized by different geometries and porosities. Drag and lift forces were measured to quantify debris–flow–structure interactions. The results show that drag and lift coefficients increase with blockage ratio and water level difference, whereas they decrease with Froude number and proximity ratio. Moreover, debris porosity and geometry have a negligible effect on drag coefficient but significantly influence lift coefficient. In the tested range of Reynolds numbers, both coefficients are not affected by the flow regime, with all other parameters being constant. Based on experimental evidence and dimensional analysis, empirical equations were derived for estimating drag and lift coefficients. To the best of the authors’ knowledge, for the first time, the proposed predictive relationships account for all the above-mentioned hydraulic and geometric variables, providing useful tools for improving the design and resilience of bridge infrastructures. Full article

Puerarin is a naturally occurring isoflavone with reported anticancer activity, yet its topical translation is constrained by limited stability and suboptimal dermal delivery. A Puerarin-loaded proniosomal gel was developed as a potential dermal delivery platform, and we performed an initial assessment of its antimelanoma activity and safety. The gel was produced by coacervation–phase separation using Span 60, Tween 80, phosphatidylcholine, and cholesterol. Physicochemical characterization included pH, entrapment efficiency, rheology, FTIR, DSC, and vesicle properties (DLS, PDI, ζ-potential). In silico geometry optimization and docking were carried out for melanoma-associated targets (MITF and DNMT3B). Biological effects were investigated in vitro on A375 melanoma cells using MTT, morphological analysis, and nuclear/mitochondrial staining, while irritation potential was evaluated in ovo by HET-CAM. The optimized formulation exhibited a skin-compatible pH and an entrapment efficiency of 62 ± 0.26%. DLS indicated a multimodal population, with a major number-weighted vesicle population in the 100–200 nm range, and a ζ-potential of −34.9 ± 0.14 mV. FTIR and DSC supported component incorporation without evidence of chemical incompatibility. The gel showed non-Newtonian, pseudoplastic, thixotropic flow, which is advantageous for topical use. Docking predicted meaningful affinities of Puerarin toward MITF and DNMT3B. The formulation reduced A375 viability in a dose-dependent manner (to 44.66% at 200 µg/mL) and, at higher concentrations, produced nuclear condensation and disruption of the mitochondrial network. HET-CAM classified the gel as non-irritant. The Puerarin-loaded proniosomal gel represents a promising topical platform with preliminary in vitro antimelanoma cytotoxic potential, warranting additional studies to validate skin delivery, efficacy, and safety. Full article

Systematic investigation into the structural integrity of adjustable ejectors, particularly concerning thermal–fluid–structural (TFS) coupling, is currently lacking. Utilizing the Workbench platform, this study performs unidirectional steady-state TFS coupling numerical simulation of the adjustable air ejector under off-design conditions to systematically analyze its internal flow characteristics and structural mechanical responses across various needle openings. The results show that thermal load is the dominant factor governing the ejector’s structural stress and deformation. The overall deformation is primarily characterized by axial elongation, with the maximum thermal deformation localized at the ejector’s exit section. The nozzle exit is identified as the primary structural weak point, exhibiting the highest local stress, which peaks at 196.8 MPa when the needle opening is minimized. Shock train structures extending from the nozzle’s divergent section into the mixing chamber, coupled with the axial displacement of the needle, significantly influence the ejector’s thermal deformation and thermal stress. Based on the thermally dominated stress mechanism identified, this study proposes a composite nozzle design utilizing a nickel-plated Invar alloy substrate. This material fully leverages Invar alloy’s low thermal expansion to mitigate thermal stress and deformation while the nickel plating ensures corrosion resistance, thereby significantly enhancing the nozzle’s mechanical properties and operational reliability in thermal environments. The findings of this analysis are applicable to off-design evaluations under unidirectional steady-state coupling conditions, providing a valuable reference for the structural design and strength optimization of similar ejectors operating in high-temperature, unsteady environments. Full article

The impact of sewage discharge on water quality in reversing rivers has rarely received attention. This study simulated water quality changes in Maoergang River (a water body with counter flow conditions) affected by effluent discharge from Yangjiabu Sewage Treatment Plant. The results revealed that the diffusion patterns of COD, NH₄⁺-N, and TP in the study area were largely consistent; however, different hydrological conditions and discharge scenarios resulted in obvious differences in pollutant distribution. During the dry season, regardless of normal or counter folow conditions, the Maoergang and Xitiaoxi downstream were the primary affected segments. Regulated by hydrodynamic forces, under normal flow conditions, the Xitiaoxi downstream received a higher pollutant load while the Xitiaoxi upstream received minimal inputs. In the wet season, pollutant concentrations were generally lower due to the dilution effect of increased runoff; notably, the primary affected segments shifted to the downstream reaches of Maoergang and Huanchenghe. Under accidental discharge scenarios, excessive sewage release expanded the scope of pollution impacts, with elevated pollutant concentrations causing water quality non-compliance in parts of the upstream and downstream Xitiaoxi—both of which are within the germplasm resource protection zone. Predictive analysis indicated that when the sewage treatment plant’s discharge was reduced to 1.0 × 10⁴ t·d⁻¹, the receiving water bodies could still meet local water quality standards, even under the counter flow hydrological conditions, which pose the greatest threat to water quality during the dry season. Full article

Background: While intravenous administration of nanoparticles (NPs) is effective for targeting the lungs and liver, directing them to other organs and tissues remains challenging. Methods: Here, we report alternative administration routes that improve organ-specific accumulation of poly (lactic-co-glycolic acid) (PLGA) NPs (100 nm, negatively charged) loaded with the near-infrared dye Cyanine 7 (Cy7). NP cytotoxicity was evaluated in HEK293, mMSCs, C2C12, L929, and RAW264.7 cells. Hemocompatibility was assessed using WBCs and RBCs. NPs were administered via the tail vein, carotid, renal, and femoral arteries in BALB/c mice. Administration safety was evaluated by laser speckle contrast imaging and histological analysis. NP biodistribution and accumulation were assessed using in vivo and ex vivo fluorescence tomography and confocal microscopy of cryosections. Results: PLGA-Cy7 NPs demonstrate low cytotoxicity even at high doses and exhibit good hemocompatibility. Administration of NPs through the mouse carotid, renal, and femoral arteries significantly increases accumulation in the target ipsilateral brain hemisphere (31.7-fold) and salivary glands (28.3-fold), kidney (13.7-fold), and hind paw (3.6-fold), respectively, compared to intravenous administration. Injection of NPs through arteries supplying the target organs and tissues does not result in significant changes in blood flow, morphological alterations, or irreversible embolization of vessels, provided the procedure is performed correctly and the optimal dosage is used. Conclusions: These results highlight the potential of intra-arterial delivery of NPs for organ-specific drug targeting, underscoring the synergistic impact of advances in materials science, minimally invasive endovascular surgery, and nanomedicine. Full article

Modern power systems have become increasingly complex, making the detailed modeling and analysis of large-scale networks computationally demanding and often impractical. Therefore, network reduction techniques are essential for representing a smaller area of interest while preserving the electrical behavior of the complete system. For electromagnetic transient (EMT) studies, such as load rejection analysis, reduced networks are commonly derived using classical methods like Kron reduction under maximum power transfer conditions. However, this approach can lead to discrepancies in load flow and short-circuit levels between the reduced and complete systems. In addition, Kron reduction may introduce negative resistances in the reduced-order model, compromising system stability by producing non-passive equivalents and potentially causing unrealistic or numerically unstable EMT simulations. To address these limitations, this paper proposes an optimization-based approach, termed PSO-OPF-Kron, which integrates Optimal Power Flow (OPF) with the Particle Swarm Optimization (PSO) algorithm to refine the equivalent network parameters. The method optimally determines power injections, bus voltages, transformer tap settings, and impedances to align the reduced model with the full system’s operating point and short-circuit levels. Validation on the IEEE 39-bus system demonstrates that the proposed method significantly improves accuracy and numerical stability, ensuring reliable EMT simulations for load rejection studies. Full article

The sustained growth of electricity demand and the global transition toward low-carbon energy systems have intensified the need for efficient, flexible, and reliable operation of electrical distribution networks. In this context, the coordinated integration of distributed renewable energy resources and demand-side flexibility has emerged as a key strategy to improve technical performance and economic efficiency. This work proposes an integrated optimization framework for active power supply in a radial, distribution-like network through the optimal siting and sizing of photovoltaic (PV) units and wind turbines (WTs), combined with a real-time pricing (RTP)-based demand-side response (DSR) program. The problem is formulated using the branch-flow (DistFlow) model, which explicitly represents voltage drops, branch power flows, and thermal limits in radial feeders. A multiobjective function is defined to jointly minimize annual operating costs, active power losses, and voltage deviations, subject to network operating constraints and inverter capability limits. Uncertainty associated with solar irradiance, wind speed, ambient temperature, load demand, and electricity prices is captured through probabilistic modeling and scenario-based analysis. To solve the resulting nonlinear and constrained optimization problem, an Improved Whale Optimization Algorithm (I-WaOA) is employed. The proposed algorithm enhances the classical Whale Optimization Algorithm by incorporating diversification and feasibility-oriented mechanisms, including Cauchy mutation, Fitness–Distance Balance (FDB), quasi-oppositional-based learning (QOBL), and quadratic penalty functions for constraint handling. These features promote robust convergence toward admissible solutions under stochastic operating conditions. The methodology is validated on a large-scale radialized network derived from the IEEE 118-bus benchmark, enabling a DistFlow-consistent assessment of technical and economic performance under realistic operating scenarios. The results demonstrate that the coordinated integration of PV, WT, and RTP-driven demand response leads to a reduction in feeder losses, an improvement in voltage profiles, and an enhanced voltage stability margin, as quantified through standard voltage deviation and fast voltage stability indices. Overall, the proposed framework provides a practical and scalable tool for supporting planning and operational decisions in modern power distribution networks with high renewable penetration and demand flexibility. Full article

This work presents a lightweight and interpretable framework for the early warning of voltage stability degradation in distribution networks, based on fractal and spectral features from flow measurements. We propose a Fast Voltage Stability Index (FVSI), which combines four independent indicators: the Detrended Fluctuation Analysis (DFA) exponent α (a proxy for long-term correlation), the width of the multifractal spectrum Δα, the slope of the spectral density β in the low-frequency range, and the $c_2$ curvature of multiscale structure functions. The indicators are calculated in sliding windows on per-node series of voltage in per unit Vpu and reactive power Q, standardized against an adaptive rolling/first-N baseline, and anomalies over time are accumulated using the Exponentially Weighted Moving Average (EWMA) and Cumulative SUM (CUSUM). A full online pipeline is implemented with robust preprocessing, automatic scaling, thresholding, and visualizations at the system level with an overview and heat maps and at the node level and panel graphs. Based on the standard IEEE 13-node scheme, we demonstrate that the Fractal Voltage Stability Index (FVSI_Fr) responds sensitively before reaching limit states by increasing α, widening Δα, a more negative $c_2$, and increasing β, locating the most vulnerable nodes and intervals. The approach is of low computational complexity, robust to noise and gaps, and compatible with real-time Phasor Measurement Unit (PMU)/Supervisory Control and Data Acquisition (SCADA) streams. The results suggest that FVSI_Fr is a useful operational signal for preventive actions (Q-support, load management/Photovoltaic System (PV)). Future work includes the calibration of weights and thresholds based on data and validation based on long field series. Full article

The paper presents the development of analytical and finite element models, focusing on both magnetostatics and thermal solutions, of axial classical and hybrid active magnetic bearings (AMBs). An improved hybrid axial AMB design is proposed, combining permanent magnets and an electromagnet, where the bias magnetic flux is provided by the permanent magnets. This configuration significantly reduces the power consumption and heat generation. Numerical modeling is conducted using 2D magnetostatic and both 2D and 3D thermal finite element analysis. The study focuses on the system’s mass reduction, electrical power consumption, and heat flow output while maintaining the bearing’s load capacity. Digital control systems and algorithms have been developed and fabricated for both axial classical and hybrid axial AMBs, using an ESP32 microcontroller. Two experimental setups have been designed, fabricated, and tested. Full article

This study reports the thermodynamic performance of a patented compact vertical evaporator–absorber unit for LiBr–H₂O absorption cooling, extending Part I by translating validated prototype data into a rigorous control-volume assessment of coupled transport. Coolant-side calorimetry was used to determine the absorption heat-transfer rate (Q_abs), while a mass–energy balance provided an estimate of the absorption mass-transfer rate (${∆\dot{m}}_{abs}$) across twelve manually imposed thermal-load phases with tagged fan-OFF/ON sub-intervals. Linear trend (slope) analysis was applied to quantify phase-resolved dynamic behavior. Fan assistance produced three load-dependent regimes: (i) stabilization of downward trends under low and zero loads, yielding slope-based relative improvements above 100% in the most critical weak-gradient phases; (ii) acceleration of recovery at intermediate loads; and (iii) moderation of strongly positive drifts at high loads. The global thermal resistance ($R_{th}$) decreased by more than 30% in passive and low-load phases, and Wilcoxon signed-rank tests confirmed statistically significant reductions in most intervals (p < 0.05). Uncertainty contributions and robustness were quantified through an uncertainty budget decomposition and sensitivity analyses, and a subsystem-level normalization (η_EA = Q_abs/Q_in) is reported to support comparisons across loads without invoking cycle COP. Overall, active vapor-flow management using a low-power internal fan widens the useful operating envelope of compact absorbers and provides a validated thermodynamic baseline with practical, regime-aware control guidelines for decentralized low-carbon cooling technologies. Full article

Background: Canine leishmaniasis is notoriously difficult to manage by chemotherapy alone, necessitating the consideration of supplemental or alternative treatment. Evidence is presented to support the feasibility of immunotherapy of diseased dogs through vaccination. Methods: The vaccine format used consisted of cultured promastigotes of Leishmania infantum, which were rapidly and completely killed by intracellularly generated singlet oxygen. A total of 33 owned dogs of different breeds and ages diagnosed positive for leishmaniasis were enrolled and divided into three groups for treatments as follows: (1) immunotherapy alone (9 dogs); (2) immunotherapy after chemotherapy (14 dogs); and (3) chemotherapy alone (10 dogs). All dogs in Groups 1 and 2 received intradermally three identical dosages of the vaccine format mentioned at the same schedules. The outcomes were assessed for one year at a post-treatment interval of 2–4 months by determining lymph node parasite loads and clinical scores based on established methodologies. Results: Spaghetti plots of the values for parasite loads obtained revealed that they scattered widely over time with a significant decline by 8–12 months post-treatment in all three groups. Sankey plots of clinical scores in stacked bars also showed that they followed erratic patterns of flow over time, albeit toward lower levels in all cases. Ordinal logistic regression analysis of clinical scores indicated that, while the odds for the emergence of severe clinical symptoms declined in all three groups, the lowest risk was associated with Group 2 dogs treated with immunotherapy after chemotherapy. The evidence presented thus suggests that immunotherapy of the diseased dogs with the vaccine format diminished their parasite loads and improved their clinical scores, especially when applied after chemotherapy. Dogs in Groups 1 and 2 that received immunotherapy, on average, lived twice as long as those in Group 3 that received chemotherapy alone. The risk of death estimated by analysis of the clinical scores using the Cox proportional hazard model was also found to be lower for Groups 1–2 dogs receiving immunotherapy than those in Group 3 receiving chemotherapy alone. Conclusions: Post-therapeutic survival time thus may be an additional parameter suitable to assess treatment efficacy by vaccination. In vitro approaches to mitigate some limitations of this study were proposed for future investigation. Full article