Search Results (2,327)

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

This study presents a comparative analysis of energy consumption and gaseous emissions from a compressed natural gas (CNG)-fueled vehicle under real driving emissions (RDE) conditions and values predicted using machine learning (ML) models developed from chassis dynamometer data. The analyzed components included energy consumption (EC) as well as carbon dioxide (CO₂), carbon monoxide (CO), total hydrocarbons (HC), methane (CH₄), and nitrogen oxides (NO_X). The models were trained using a limited set of easily accessible predictors, namely vehicle speed and acceleration. A hybrid modelling approach was proposed, combining laboratory data with validation under real-world conditions. Additionally, road load power (P_rl) was introduced as a novel predictor representing vehicle operating load. The results demonstrate that the models effectively capture emission trends, with the highest agreement obtained for CO, CO₂. The inclusion of P_rl improved prediction accuracy, which increased from approximately 64% to 71% for CO and from 57% to 61% for HC. For CO₂, the model achieved about 80–82% agreement with RDE measurements, with analogous levels obtained for EC. A key advantage of the proposed methodology is its reliance on a limited number of input variables, which enhances practical applicability while maintaining satisfactory accuracy. Furthermore, the use of precise laboratory data improves model robustness, and the approach enables the estimation of methane (CH₄), which is typically not measured by standard portable emissions measurement systems (PEMSs). The results confirm the effectiveness of the hybrid ML framework and highlight the importance of incorporating load-related parameters in real-world emissions and energy consumption modeling. Full article

Pultrusion is an efficient continuous manufacturing process for fiber-reinforced polymer (FRP) composites, but conventional open-bath impregnation has limitations such as resin exposure, quality variation, and resin loss. To overcome these limitations, closed-injection pultrusion (CIP) and short-pot-life resin systems have recently been introduced. However, the effects of processing variables on the quality and properties of composites manufactured using such resin systems have not been fully clarified. In this study, the effects of resin viscosity and pulling speed on the quality and mechanical properties of carbon FRP (CFRP) and glass FRP (GFRP) composites manufactured by CIP were investigated. CFRP and GFRP composites were fabricated at resin temperatures of 30 and 40 °C and pulling speeds of 300, 400, and 500 mm/min. The manufactured composites were evaluated in terms of void content, microstructure, hardness, and tensile properties. The results showed that increasing pulling speed increased void content and promoted macrovoids and locally poor impregnation, whereas the influence of resin temperature was relatively limited. Hardness, tensile strength, and elastic modulus decreased as pulling speed increased. These results demonstrate that CFRP and GFRP composites can be successfully manufactured by CIP using short-pot-life resin systems, and that precise control of resin viscosity and pulling speed is essential for achieving high quality and mechanical performance. 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 investigates the potential of several sustainable agricultural by-products—including olive stones, cork, and almond shells, which are locally available in Alentejo, Portugal—as low-cost adsorbents for the removal of methylene blue (MB) from synthetic wastewater. The biomass residues were evaluated both in their raw form and after conversion into activated carbons (ACs) through chemical activation with KOH at 973 K. The produced ACs exhibited well-developed surface areas (760–1103.5 m² g⁻¹) and porous structures (0.31–0.51 cm³ g⁻¹). The adsorbents were characterised in terms of their chemical and textural properties. Raw biomass materials presented acidic surface groups, whereas the ACs presented neutral or basic groups. Batch adsorption experiments were conducted to assess the effects of adsorbent particle size, solution pH, initial MB concentration, stirring speed, contact time, and temperature on dye removal efficiency. Among all tested materials, the ACs achieved superior MB adsorption capacities, ranging from 244.2 to 317.6 mg g⁻¹, compared to the untreated biomass adsorbents, which showed capacities between 34.1 and 46.4 mg g⁻¹. The adsorption data were best described by the Langmuir isotherm model, while the kinetic data closely followed the pseudo-second-order (PSO) model. Thermodynamic analysis revealed that MB adsorption was spontaneous and endothermic; however, the relatively low enthalpy values indicated that physical interactions contributed significantly, particularly in the case of the raw biomass adsorbents. This suggests that the PSO model may also be applicable when physical adsorption is the dominant mechanism. This work demonstrates the novel use of cork, olive stone, and almond shell biomasses and their derived ACs as sustainable adsorbents, highlighting an integrated approach that simultaneously promotes efficient wastewater treatment, waste valorisation, and circular economy-driven socio-economic development. Full article

Joining dissimilar polymers such as polypropylene (PP) and high-density polyethylene (HDPE) remains a challenge in modern manufacturing due to their incompatible thermal properties and poor interfacial bonding. In this study, a novel hybrid structure was fabricated by laser welding of PP to an HDPE matrix reinforced with 3 wt% carbon nanotubes (CNTs). The CNTs were incorporated via fused filament fabrication (FFF) 3D printing to raise the melting temperature and thermal stability of HDPE, thereby minimizing the thermal mismatch with PP. A pulsed CO₂ laser was used to perform butt welding, and the influences of pulse frequency, welding speed, and laser power on the elastic modulus and tensile properties of the weld samples were thoroughly studied. A response surface design was employed to build predictive models and perform multi-objective optimization. The addition of CNTs, as evidenced by differential scanning calorimetry (DSC), elevated the crystallinity level of HDPE from 48.3% to 53.1% and the melting point from 137.8 to 140.8 °C, making its thermal properties more comparable to those of PP. Observations via scanning electron microscopy (SEM) indicated that when the optimal parameters were applied (pulse frequency: 35 Hz, welding speed: 21 mm/s, and laser power: 49 W), the joint line was defect-free, fully fused, and contained very few voids. At these settings, the model estimated an elastic modulus of 793 MPa and a tensile strength of 49.6 MPa, while confirmation experiments yielded 47.2 MPa and 764.5 MPa, respectively, with relative errors below 5%. The results demonstrate that the combination of CNT-assisted laser welding and RSM-driven optimization effectively resolves the thermal incompatibility of HDPE and PP, thereby facilitating high-quality joining of dissimilar polymers for applications in packaging and automotive fields. Full article

As a typical model of urban green and sustainable micro-transportation, shared electric bicycles play a crucial role in short and medium-distance travel as well as in connecting with public transportation. To respond to the national concept of low-carbon travel, this study takes users of urban shared electric bicycles in Kunming, Yunnan Province as the research sample and distributes questionnaires online through the Wenjuanxing platform to conduct an investigation into the factors influencing residents’ short-term and long-term continuance usage intention of shared electric bicycles. The results of the ordered logit model show that: at the level of personal attributes, the number of family-owned electric bicycles exerts a negative impact on residents’ short-term and long-term willingness to continue using shared electric bicycles. In terms of travel attributes, travel frequency has a positive impact on residents’ long-term continuance usage intention of shared electric bicycles, while exerting little influence on their short-term continuance usage intention. As for the original travel modes, groups with the habit of walking show a rejection of shared electric bicycles. From the perspective of attitudinal perceptions, independent variables reflecting instantaneity characteristics such as riding speed, unlocking speed and easy electric bicycle returning have a promoting effect on residents’ short-term continuance usage intention; independent variables reflecting sustainability characteristics such as good endurance capacity contribute to residents’ long-term continuance usage intention, while the overall travel comfort has a positive effect on the continuance usage intention across all time periods. Based on the model results, this paper puts forward policy recommendations from four aspects to promote urban residents’ continuance usage intention of shared electric bicycles. Full article

Hydrogen is a promising carbon-neutral fuel for future internal combustion engines due to its wide flammability range, high flame speed, and absence of carbon-based emissions. However, its high reactivity significantly increases susceptibility to abnormal combustion phenomena such as knock and pre-ignition, which can compromise engine efficiency, durability, and operational stability. Accurate detection and characterization of knock in hydrogen-fueled spark-ignition engines remain challenging due to the highly transient, broadband, and cycle-dependent nature of abnormal combustion-induced pressure oscillations. Conventional knock indicators based solely on time-domain pressure oscillations or fixed-band frequency analysis are limited in their ability to capture transient resonance behavior and cyclic variability. This study presents an integrated frequency- and time–frequency-domain methodology for knock detection using high-resolution in-cylinder pressure data acquired from a single-cylinder research engine operating under hydrogen port fuel injection (PFI). A discrete Fast Fourier Transform (DFFT) approach applied at stationary points of dynamically windowed pressure signals enables accurate identification of dominant resonance modes while minimizing spectral leakage. A Gaussian-based adaptive windowing strategy is introduced to capture combustion-driven cyclic variations more effectively. Short-Time Fourier Transform (STFT) and sum-based spectral analysis further provide detailed time–frequency localization of transient knock events. The proposed methodology demonstrates a clear separation between normal combustion and knock conditions, enabling reliable cycle-by-cycle identification of abnormal combustion events under varying operating conditions. The experimentally observed resonance frequencies are validated against theoretical predictions using Draper’s acoustic resonance equation, supporting the physical interpretation of knock-induced pressure oscillations. The results demonstrate that the proposed adaptive spectral methodology significantly improves knock detection accuracy compared to conventional indicators and provides a robust framework for advanced knock diagnostics, engine calibration, and combustion control in hydrogen-fueled engines. Full article

This paper presents a case study demonstrating the power quality improvements in a 24 kV distribution system at a liquefied natural gas (LNG) industrial plant with variable speed drives (VSDs), the conventional capacitor bank, and a rooftop solar photovoltaic system. Solar photovoltaic (PV) inverters can supply harmonic currents to the grid, potentially affecting the system and causing maloperation of sensitive equipment in both the utility systems and neighboring industries connected to it. Therefore, the installation of shunt active power filters (APFs) in a 400 V system was proposed in this study. The installed locations were varied, and the corresponding power qualities were analyzed. The results were examined in terms of design and harmonic elimination. Simulations were conducted using the PSCAD/EMTDC software version 4.5. The power quality simulation and field measurement results after the APF installation were compared to demonstrate the effectiveness of the proposed solutions. The addition of APFs was found to improve the power quality. In addition to the mechanism analysis, the economic feasibility of the proposed approach was investigated. The costs of APF installation in various locations were analyzed. The results show that the proposed method can improve the power supply at a reasonable price. This work contributes to sustainable industrial energy systems by improving the reliability and power quality of photovoltaic-integrated electrical networks, thereby supporting higher penetration of renewable energy resources and stable low-carbon industrial operation. Full article

This study investigates the fabrication of laser-scribed graphene (LSG) electrodes on polyimide substrates using a CO₂ laser cutter for label-free L-Histidine detection in artificial sweat. Two-level full factorial and central composite designs were employed to optimize critical manufacturing parameters, including laser speed, power, and electrode width. Electrochemical characterization using cyclic voltammetry with K₃Fe[CN]₆ demonstrated superior LSG electrode performance compared to standard glassy carbon electrodes, exhibiting a 702 ± 62% higher oxidation current peak at 0.56 mM K₃Fe[CN]₆ in 0.1 M KCl. We successfully demonstrated the label-free electrochemical detection of L-Histidine in artificial sweat using these LSG electrodes. The results show a linear relationship (R² = 0.987) between current peak and L-Histidine concentration within the 8.3 mM to 50 mM range, demonstrating high sensitivity towards L-Histidine. These findings highlight the potential of this optimized LSG electrode fabrication approach for developing high-performance, user-friendly, and disposable wearable biosensors for real-time and non-invasive health monitoring applications in sweat analysis. Full article

This study explores key technological challenges and innovative strategies for improving the combustion performance and emission characteristics of low-carbon fuel engines, with a focus on natural gas applications. The core bottlenecks of natural gas combustion, including slow combustion speed and high methane slip under lean burn conditions due to wall quenching, crevice effects, and the long distance of flame propagation from the ignition zone to the whole cylinder, are analyzed. The decarbonization of engines further aggravates these issues. Technological solutions are summarized in four categories, including turbulence enhancement, high-energy ignition, fuel reactivity modification, and fuel synergy with zero-carbon fuels. Geometry modifications of the combustion chamber, dual-fuel operation, pre-chamber ignition, and fuel activation are systematically reviewed and evaluated. A fusion technology integrating diesel pilot ignition with jet flame propagation is analyzed as a new combustion concept, termed induced jet flame combustion. This approach demonstrates significant potential in enhancing both combustion efficiency and stability, especially for lean burn conditions. This work highlights the role of natural gas engines as a transitional technology and a support platform for ultralow-emission and high-efficiency power systems fueled with low/zero-carbon fuels in the context of global decarbonization goals. Full article

Carbon-fiber-reinforced polymer (CFRP) components commonly require milling to achieve final dimensional accuracy and surface integrity, yet tool selection remains a trade-off between surface quality, process load, and cost. This study compared two industrial tool concepts for CFRP side milling under matched cutting conditions: a WC-Co compression-type end mill and a PCD end mill. A two-factor central composite design with 13 parameter sets was used, and tool effects were evaluated through paired differences in Ra_mean, Rz_mean, and F_xy,RMS. The PCD tool significantly improved surface quality, with mean paired differences of −2.00 µm for Ra_mean and −6.67 µm for Rz_mean, while increasing F_xy,RMS by 14.86 N relative to WC-Co. Response-surface analysis showed that the roughness advantage of PCD was broadly stable across the investigated process window, whereas the force penalty was nonlinear and was best described by a second-order CCD model (R² = 0.820, model p = 0.015), with a significant quadratic cutting-speed term. Scenario-based decision analysis further showed that PCD was preferred in 12 of 13 DOE points under quality-driven weighting, whereas WC-Co was preferred in all 13 points under cost-driven weighting. The results indicate that PCD is the preferred quality-oriented solution for CFRP side milling, while WC-Co remains advantageous when lower load or lower cost is prioritized. Full article

The dissimilar joining of aluminum alloy and carbon fiber-reinforced polymer (CFRP) is critical for lightweight manufacturing in transportation and aerospace sectors, yet it remains challenging due to their substantial differences in physical and chemical properties. This paper systematically reviews friction stir welding (FSW) of aluminum alloy and CFRP, and compares it with laser welding, induction welding, resistance welding, and ultrasonic welding. The comparative analysis indicates that while each alternative process presents distinct limitations in thermal management, heating uniformity, or joint configuration, FSW demonstrates the most balanced overall performance, uniquely combining single-pass long-distance capability, low heat input, and broad industrial applicability. Through systematic parametric analysis, the optimal FSW processing window is quantitatively established as a tool rotation speed of 1200–1500 rpm combined with a traverse speed of 30–50 mm/min. Under these optimized conditions, the CFRP side remains below its thermal degradation threshold of 350 °C, the defect volume fraction is reduced from 12% to below 3%, and the maximum joint tensile strength reaches 78 MPa, representing 65% of the base CFRP strength. The interfacial bonding mechanisms are identified as mechanical interlocking and localized chemical bonding, which however cover only approximately 30% of the interfacial area. Optimization strategies, including surface modification, auxiliary structures, nanoparticle reinforcement, and external field assistance, are evaluated for their effectiveness in improving joint quality. Finally, critical challenges and future research directions toward engineering application are outlined. Full article

Tool wear in CNC milling increases friction and torque demand at the tool-workpiece interface, which is reflected in spindle motor current. This study develops a non-intrusive tool wear condition classification method using spindle motor current monitoring during practical CNC milling of commercial medium-carbon steel workpieces (JIS S50C/AISI SAE 1050-equivalent; as-received and non-heat-treated; nominal laboratory hardness approximately 4.3 HRC). Experiments were performed on a Tongtai MDV-508 vertical machining center at fixed cutting conditions (3000 rpm spindle speed, 2 mm axial depth of cut, 5 mm cutting width, and 300 mm/min feed rate) using eight TiAlN-coated fine-grain WC–Co solid carbide end mills (10 mm diameter, four flutes; nominal Co binder approximately 10 wt%). An oil-based HS Highstart/HS-SSHS-BH10 cutting fluid was applied through the machine external coolant nozzle in flood mode at an estimated nominal flow rate of approximately 3 L/min and near-room coolant temperature (25 ± 2 °C), and was used as supplied without dilution. A clamp-type AC current sensor was installed on one phase line supplying the spindle motor, and current was acquired using an NI-9221 module at 20 kHz. Cutting intervals were isolated by envelope-based segmentation, concatenated, and divided into 1 s windows (0.5 s overlap) for feature extraction. Three feature sets were evaluated: time-domain statistics, frequency-domain statistics, and an FFT→PCA hybrid representation. Tool states (New, Mid-life, Old) were labeled using post-process surface roughness Ra thresholds supported by microscope observation. The PCA transformation was fitted only on training data and then applied to the held-out test data. A logistic regression classifier achieved 97.44% test accuracy (152/156 windows; 95% Wilson CI: 93.59–99.00%) with the PCA-hybrid features, outperforming time-domain (89.74%) and frequency-domain (94.87%) models. The results support spindle current monitoring as a low-cost approach for quality-aligned tool condition monitoring, while the external validity remains limited to the tested machine, material, tool, coolant, and cutting-parameter combination. Full article

This study investigates the effect of partial hydrogen substitution of E10 fuel on the performance, fuel consumption, and emissions of a spark-ignition engine. Tests were carried out using a Toyota Avensis equipped with a 1ZZ-FE engine on a MAHA LPS 3000 chassis dynamometer. The engine was operated at 3000 rpm, at a vehicle speed of 50 km/h, and with an excess air ratio close to λ = 1. Four fuel cases were compared: E10H0, E10H05, E10H09, and E10H11. Results indicate that hydrogen addition reduced gasoline consumption and improved brake thermal efficiency. Specifically, at the maximum load point, gasoline consumption decreased from 8.2 kg/h to 6.0 kg/h, while the maximum brake thermal efficiency increased from 0.311 for E10H0 to 0.328 for E10H05. Hydrogen addition also reduced CO, HC, and CO₂ emissions. At 32 kW, CO decreased from 0.116% to 0.056%; HC, from 6.3 ppm to 3.6 ppm; and CO₂, from 15.0% to 11.6%. NO_x increased from 17 ppm to 24 ppm. The results show that hydrogen addition can reduce gasoline consumption and carbon-based emissions, but the hydrogen fraction must be optimized to limit NO_x formation. Full article