Search Results (3,432)

Next-generation unmanned aerial vehicles require compact propulsion systems capable of providing efficient vertical lift, rapid thrust vectoring, and improved maneuverability. Cyclorotors represent a promising alternative to conventional propellers, but their aerodynamic behavior is governed by highly unsteady blade–wake interactions, making performance prediction challenging. This study investigates a four-bladed cyclorotor equipped with NACA 0012 airfoils using transient computational fluid dynamics simulations and a calibrated semi-analytical blade-element model. The numerical analysis was performed over a rotational-speed range of 368–2305 rpm and for several pitch-amplitude configurations, including 5°, 7.5°, 10°, 12.5° and 15°. The results showed that the favorable pitch amplitude decreases with increasing rotational speed, shifting from larger amplitudes at low RPM to approximately 5° at higher RPM values. The semi-analytical model reproduced the main CFD trends for lift, drag, moment, and power, providing a reduced-order tool for preliminary cyclorotor performance estimation. The comparison confirmed that pitch-amplitude selection strongly influences aerodynamic loading and efficiency and should therefore be adapted to the operating regime. The proposed CFD-based methodology, supported by semi-analytical modelling, provides a useful framework for the aerodynamic characterization and early-stage optimization of cyclorotor propulsion systems for UAV applications. Full article

Loading fluctuations cause structural responses such as deformations and vibrations on the propeller. Structural response of propellers results in vibrations on the shaft system or even the hull. Considering the demand for structural safety, the correlation between structural response of propellers and inflow conditions is numerically studied in the present paper. The interaction between the propeller and turbulence structures and vortex shedding from upstream structures is considered. Loading fluctuations on the propeller blade are obtained by a turbulence model of improved delayed detached eddy simulations (IDDESs). The deformations and vibrations of propeller blades fixed at their roots are captured considering fluid–structure interaction. Results show that the loading fluctuations and vibrations on the propeller contain tonal components occurring at harmonics of shaft frequency and broadband components. Inhomogeneous inflow amplifies pressure fluctuations as a product of space frequency and shaft frequency (SF). Inhomogeneous inflow also results in more intense fluctuations of velocity in the tip vortex at SF and blade wake at blade passing frequency and encounter frequency. As a result of loading fluctuations, the vibration of the blade is a superposition of excited vibrations and natural vibrations. Inhomogeneous inflow amplifies the vibrations at the encounter frequency. Resonance of the blade can be observed when the excited frequency approaches the first natural frequency. Full article

Background: Uncontrolled hemorrhage, especially at non-compressible sites, remains a major cause of preventable trauma deaths. This study reports the development of fibrinogen-loaded calcium carbonate (CaCO₃) microparticles that combine hemostatic activity with self-propelling capability for targeted delivery against blood flow, with a focus on understanding formulation-dependent trade-offs among particle yield, protein loading, clotting performance, and transport behavior. Methods: Microparticles were synthesized via a precipitation method using different carbonate sources and characterized for yield, morphology, size, and fibrinogen encapsulation. Hemostatic function was assessed using rotational thromboelastometry (ROTEM) in fibrinogen-deficient plasma. Propulsion behavior was evaluated following exposure to protonated tranexamic acid (TXA⁺), which triggers CO₂ generation. Particle size and encapsulation were examined by microscopy and fluorescence imaging. Results: The precipitation method produced spherical micrometer-sized particles, with fibrinogen inclusion reducing yield and particle size relative to unload controls. Fluorescence microscopy confirmed successful encapsulation. Encapsulation efficiency varied with formulation, with sodium carbonate-based particles showing higher relative fibrinogen loading. ROTEM analysis demonstrated that fibrinogen-loaded particles significantly improved clot formation, increasing maximum clot firmness compared to fibrinogen-free particles, although performance remained formulation-dependent. TXA⁺-triggered propulsion achieved maximum speeds up to 4.221 cm/s. Fibrinogen-loaded particles exhibited longer activation lag times than unloaded particles, indicating a trade-off between hemostatic functionality and propulsion kinetics. Conclusions: Fibrinogen-loaded CaCO₃ microparticles exhibit both hemostatic activity and chemically triggered motion in vitro. The study identifies key formulation-dependent trade-offs between particle yield, fibrinogen loading, clotting performance, and propulsion behavior. While these findings support the feasibility of combining localization and clot stabilization mechanisms, further studies under physiologically relevant flow conditions and in vivo models are required to evaluate their potential for active delivery in non-compressible hemorrhage. Full article

To address the time-consuming and labor-intensive procedures associated with traditional approaches for evaluating the integrated burning rate of wire-embedded propellants in solid rocket motors (SRMs), this study proposes an efficient and reliable prediction method. This new method is based on an improved burning-rate–initial-temperature correlation, achieved through Abaqus-Python secondary development that enables fully automated geometric modeling, transient heat-transfer analysis, and temperature-field extraction for wire-embedded propellants. The relative error between the present method and the experimental results is less than 5%. The accuracy and engineering applicability of the present method are verified. The effects of the material parameters and wire diameters on the integrated burning rate is investigated. The results indicate that wires of different materials exhibit substantial variations in burning-rate enhancement efficiency, with smaller diameters and higher thermal diffusivity producing stronger enhancement effects. When the specific heat capacity and density are held constant, the integrated burning rate increases monotonically with the wire’s thermal conductivity, though the growth trend gradually approaches saturation. In contrast, the influences of the wire’s specific heat capacity and density are comparatively weak. The integrated burning rate prediction framework developed in this study demonstrates strong versatility and scalability. It enables rapid performance evaluation of propellants embedded with wires of various sizes and thermophysical properties, providing valuable theoretical guidance and practical tools for the design and optimization of wire-embedded solid rocket motors. Full article

Biomedical materials, which are engineered to interact safely and effectively with biological systems, serve as the foundation of modern medicine. They facilitate precise diagnostics, targeted therapies, tissue regeneration, and the functional restoration of damaged organs and tissues. Propelled by advancements in materials science, nanotechnology, and clinical understanding, this field is rapidly evolving from passive implants to intelligent, responsive, and bioactive systems. This review summarize recent breakthroughs in four crucial domains: hard-tissue repair, dynamic wound healing, spatiotemporally controlled drug delivery, and advanced surface engineering. This article rigorously assesses the persistent translational barriers, particularly the disparity between in vitro biocompatibility assays and clinical performance, the scalability constraints in manufacturing, and the fragmentation in regulatory frameworks and international standards. By connecting fundamental innovation with real-world clinical needs, this review functions as both a strategic reference for researchers and a practical resource for clinicians exploring the next generation of biomedical materials. Full article

High-speed permanent magnet synchronous motors (PMSMs) used in electric pump-fed liquid rocket engines require stator shielding sleeves to prevent corrosive propellants from causing harm under cyclic pressure. However, metallic sleeves suffer significant losses due to eddy currents. Conversely, pure carbon fiber reinforced polymer (CFRP) sleeves have failed when exposed to 98% H₂O₂. Micro-CT analysis of a failed pump sleeve reveals a four-stage failure mechanism. Manufacturing defects caused matrix cracking, which propagated under pressure and thermal cycling. This progression resulted in the formation of through-thickness leakage paths, which ultimately triggered catalytic decomposition and explosion. To address these issues, an improved dual-layer sleeve is proposed, featuring a 2.5 mm PEEK 450G liner and a 2.0 mm T700S/epoxy CFRP overwrap. Finite Element Analysis (FEA) indicates peak von-Mises stresses of 86.25 MPa and 112.16 MPa, yielding Tsai–Wu safety factors of 2.9 and 1.7. Furthermore, various tests, including immersion, fatigue, burst, hydraulic, and thermal evaluations, demonstrate a burst margin of 2.37× at 7.12 MPa, with only 0.19% increase in mass. This design effectively eliminates leakage pathways while preserving zero eddy-current loss and ensuring a low weight. Full article

This study compares low-parameter fractional viscoelastic models for the unified characterization and extrapolation of creep and stress relaxation behaviors in polymer-based energetic materials, including polymer-bonded explosives (PBXs) and solid propellants. Fourteen candidate models composed of springs and spring-pot elements were considered under controlled parameter complexity. Their creep compliance and relaxation modulus were evaluated through Laplace-domain formulations, and the parameters were identified using a combined Talbot inverse Laplace transform and Gray Wolf Optimizer. Published creep and stress relaxation datasets were used to assess both fitting performance and early-stage data extrapolation behavior. The results show that the fractional Zener model and Model 13 can each describe both creep compliance and relaxation modulus within compact six-parameter rheological forms. Both models generally achieved coefficients of determination above 0.99. When the first 10% of the time span was used for calibration, the selected fractional models showed extrapolation capability over an approximately one-order-of-magnitude longer time window, with rRMSE values below 8.5% in reported cases and below 2% under suitable conditions. Compared with Prony series and power-law models, these fractional models offer compact alternatives for broad viscoelastic response characterization. These results provide guidance for selecting compact viscoelastic models for long-term response analysis of polymer-based energetic materials. Full article

This study investigates the controllability of a hovering platform based on ion thrust generated through the Biefeld–Brown effect. The primary objective is to examine the feasibility of stabilizing a triangular structure under laboratory conditions. To this end, three custom high-voltage power supplies were developed, each independently controlled. These power supplies can be modulated through the control loop, enabling closed-loop adjustment of thrust levels and allowing assessment of how electrode placement influences stability. Two electrode configurations were tested: edge-based placement, where thrust is produced along the triangle’s sides, and vertex-based placement, where thrust is generated near the corners. Experimental results demonstrated that, while both configurations provide similar lifting capability, the vertex-based configuration significantly improves stabilization and orientation control. The improvement stems from reduced actuator coupling and a larger effective moment arm relative to the platform’s center of mass, enabling more efficient torque generation. Full article

Predictive modeling of thermal aging in solid propellants is challenging because HTPB-based propellants are highly filled particle-reinforced polymer systems with sparse experimental data, nonlinear parameter coupling, and partially unclear aging mechanisms. This study proposes a Physics-Informed Manifold Neural Operator (PIMANO) framework for multi-parameter prediction of polymer aging in HTPB solid propellants. Accelerated thermal aging, stress relaxation, and swelling experiments were used to obtain aging temperature, aging time, crosslinking density, and viscoelastic Prony-series parameters. A continuous aging-state field was first reconstructed over the temperature–time domain by radial basis function interpolation. Crosslinking density was then introduced as a physically interpretable bridge-state variable linking aging conditions with viscoelastic responses. Among three candidate kinetic models, the modified Arrhenius–Avrami model gave the best fitting performance for crosslinking-density evolution, with R² = 0.988 and MRE = 0.0199. By combining local multi-scale neighborhood features, manifold latent representations, and DeepONet-based operator learning, PIMANO established a unified mapping from aging conditions to multi-parameter viscoelastic responses while incorporating bridge-state consistency, parameter non-negativity, and evolution-direction constraints. Under the RBF-augmented validation setting, PIMANO-ae achieved RMSE = 0.7847, MAE = 0.3366, R² = 0.9995, and MRE = 0.0027. Compared with the traditional model, RMSE, MAE, and MRE were reduced by 94.93%, 96.47%, and 96.85%, respectively. Temperature leave-one-out validation further yielded average R² values of 0.9469–0.9647 and MRE values of 4.98–6.21% at unseen aging temperatures. These results demonstrate that PIMANO provides an accurate, stable, and physically interpretable framework for multi-parameter aging prediction and life-assessment modeling of polymer-based energetic materials. Full article

High-pressure liquid CO₂ jets possess the characteristics of low-temperature cooling and dry, residue-free impact, which makes this technology particularly suitable for removing hydroxyl-terminated polybutadiene (HTPB) propellant from decommissioned solid rocket motors. However, existing studies lack multi-objective optimization of impact efficiency and CO₂ consumption, which limits their engineering applications and further promotion. In this study, a high-accuracy quadratic Response Surface Methodology (RSM) relating process parameters to damaged volume was established using a Box–Behnken design (BBD) combined with three-dimensional topography scanning. A theoretical model for CO₂ consumption was developed based on the Homogeneous Equilibrium Model (HEM). On this basis, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) was used to obtain the Pareto-optimal set for maximizing propellant damaged volume and minimizing CO₂ consumption. The results indicate that nozzle diameter has the most significant effect on damaged volume and exhibits a strong interaction with jet pressure. The knee-point solution gives a jet pressure of 15.35 MPa, a stand-off distance of 5 mm, and a nozzle diameter of 1.8 mm. Compared with the initial condition, this compromise condition increases the damaged volume by 72% while increasing CO₂ consumption by only 4.9%. Furthermore, the temperature in the impact zone was reduced to a minimum of −92.4 °C, with no thermal accumulation observed. These findings reveal the influence of liquid CO₂ jet process parameters on impact efficiency and CO₂ consumption, providing a theoretical basis and parameter references for its engineering application in the safe removal of propellants from decommissioned solid rocket motors. Full article

Antimicrobial resistance (AMR) is a leading global cause of death, with recent World Health Organization (WHO) data revealing that one in six laboratory-confirmed bacterial infections shows resistance to at least one antibiotic treatment. This review comprehensively analyzes the AMR landscape in 2026, detailing its evolution, mechanisms, and the innovative strategies being deployed to combat it. Driven by Darwinian selection and accelerated by factors like antibiotic overuse during the Coronavirus Disease 2019 (COVID-19) pandemic (predominantly in hospitalized patients with suspected bacterial co-infection), AMR is propelled by a diverse molecular arsenal in bacteria. Key mechanisms include enzymatic drug inactivation (e.g., the diversifying β-lactamase superfamily), target site modification (e.g., mcr genes conferring colistin resistance), efflux pumps, and biofilm formation. The rapid global spread of these traits is facilitated by a dynamic “mobilome”, a network of plasmids and transposons that shuttle resistance genes between species. This crisis has sparked a major scientific mobilization. Advances include the discovery of novel antibiotic scaffolds like lariocidin and the regulatory approval of critical new antibiotic/inhibitor combinations such as sulbactam/durlobactam and aztreonam/avibactam, which target highly resistant Gram-negative bacteria. Moreover, the first-in-class antibiotic gepotidacin offers a new option for urinary tract infections. Beyond traditional drugs, the pipeline is diversifying to include phage therapy, antivirulence strategies, and artificial intelligence-guided drug discovery. This diversification is critical as it helps preserve the effectiveness of existing Medically Important Antimicrobials (MIAs), those deemed essential for human medicine, by providing alternative or adjunctive treatment options. However, scientific innovation alone is insufficient. This review argues that lasting success requires parallel progress in global policy and infrastructure. Strategic priorities beyond 2026 must include finalizing and funding updated global action plans, strengthening real-time surveillance and diagnostic capacity, especially in low-resource settings, and implementing new economic models to de-risk antibiotic development. Embedding effective antimicrobial stewardship within universal health coverage and pandemic preparedness plans is crucial. Ultimately, defeating AMR demands an unprecedented, coordinated global effort that outpaces the relentless adaptability of bacterial pathogens. Full article

The urgent demand for energy-efficient CO₂ separation technologies has propelled significant advancements in polymer-based CO₂ separation membranes over the past decade. This review systematically examines three primary classes of these membrane materials: conventional dense polymer membranes, microporous polymer membranes, and mixed matrix membranes (MMMs). We analyze their distinct transport mechanisms, advantages, and the persistent challenges of permeability-selectivity trade-offs, physical aging, and scalability that have hindered widespread industrial adoption despite significant laboratory advances. Furthermore, we offer a forward-looking perspective on critical research directions, including the molecular design of stable microporous polymers, the evolution of MMMs towards continuous hybrid architectures, and the development of scalable ultrathin membrane fabrication techniques. By integrating materials innovation with engineering practicality, polymer-based membranes are poised to play a transformative role in sustainable carbon management. Full article

The pipe organ, unlike many other instruments used in so–called classical music, is inextricably entwined with technology and contemporary improvements throughout its history. The craftsmanship of organ building is closely related to the evolution of organ music, as can be seen in musical literature. These two fields have always propelled each other. This article provides a view of the author’s invention and its effect on music. The described project comprises two parts and closely links two supposedly distant fields. The first part is the instrument: a pipe organ equipped with a prototype mechatronic programmable key action. The other is the recording of the interpretations of existing baroque and contemporary literature and original improvisations, which constitutes research material and demonstrates the improved elements of artistic expression enabled by the enhanced capabilities of the prototype. Two methods of research were used: perceptual evaluation of the innovative means of expression and simplified FFT analysis of selected samples. Research results prove that automating the key action in the described manner leads to a significant expansion of the range of means of artistic expression achievable on the pipe organ. Full article

The present study conducts numerical simulations to investigate the excitation force characteristics of a pre-swirl stator–propeller–rudder system and analyzes the potential benefits of the combined pre-swirl stator and rudder bulb for vibration and noise based on force and pressure fluctuations. The propeller bearing force, rudder force and hull surface pressure are compared and analyzed under conditions with and without energy-saving devices. The results show that the pre-swirl stator and rudder bulb intensify the axial load pulsation of the propeller, which may affect the service life of the main engine and gearbox. The overall level of lateral load pulsation is also increased, which may lead to higher cabin noise. The load pulsation level of the pre-swirl stator is comparable to that of the propeller bearing force, while the increased vibration of the rudder may result in more complex structural safety and noise issues. The reduction in hull surface pressure fluctuation contributes to the mitigation of the low-frequency underwater radiated noise. The influence mechanism of the pre-swirl stator–rudder bulb on the excitation force is of great significance to the ship engineering design. Full article