Search Results (589)

In aerospace, defense, and energy systems, ceramic matrix composites (CMCs) are smart structural materials designed to function continuously in harsh mechanical, thermal, and oxidative conditions. Using high-strength fiber reinforcements and tailored interphases that enable damage-tolerant behavior, their creation tackles the intrinsic brittleness and low fracture toughness of monolithic ceramics. With a focus on chemical vapor infiltration, polymer infiltration and pyrolysis, melt infiltration, and additive manufacturing, this paper critically analyzes current developments in microstructural design, processing technologies, and interfacial engineering. Toughening mechanisms are examined in connection to multiscale mechanical responses, including controlled debonding, fiber bridging, fracture deflection, and energy dissipation pathways. Cutting-edge environmental barrier coatings are assessed alongside environmental durability issues like oxidation, volatilization, and hot corrosion. High-performance braking, nuclear systems, hypersonic vehicles, and turbine propulsion are evaluated as emerging uses. Future directions emphasize self-healing systems, ultra-high-temperature design, and environmentally friendly production methods. Full article

Aviation hydrogen internal combustion engines represent a critical pathway for rapid decarbonization due to their reliability and compatibility with existing aircraft platforms. However, the significant reduction in air density at high altitudes causes severe power degradation in naturally aspirated port-fuel-injected hydrogen internal combustion engines, making turbocharging essential for maintaining propulsion capability. This study utilizes a combined experimental and simulation framework to investigate turbocharger matching for power recovery in a 1.4 L hydrogen engine. A simulation model was constructed and validated against experimental data within a 5% error margin to ensure technical accuracy. Theoretical compressor and turbine operating parameters were derived for altitudes ranging from 4 to 8 km, comparing two boost-pressure control strategies: variable geometry turbine and waste-gate turbine. The results demonstrate that both boosting strategies successfully restore sea-level power at altitudes up to 8 km, increasing high-altitude power output by approximately four-fold to five-fold compared to naturally aspirated conditions. Specifically, the variable of geometry turbine demonstrates superior overall performance, maintaining normalized turbine efficiencies between 78.4% and 96.3% while achieving lower pumping losses and improved brake thermal efficiency. These advantages arise from the variable geometry turbine’s ability to optimize exhaust-energy utilization across varying altitudes. This study establishes a quantitative methodology for turbocharger matching, providing essential guidance for developing efficient, high-altitude hydrogen propulsion systems. Full article

This review addresses the pivotal challenge in distributed-drive electric vehicle (DDEV) dynamics control: how to optimally distribute braking and steering forces during combined maneuvers to simultaneously enhance lateral stability, safety, and energy efficiency. The over-actuated nature of DDEVs presents a unique opportunity for precise torque vectoring but also introduces complex coupled dynamics, making vehicles prone to instability such as rollover during aggressive steering–braking scenarios. Moving beyond a simple catalog of methods, this work provides a structured synthesis and evolutionary analysis of chassis control methodologies. The problem is first deconstructed into two core control objectives: lateral stability and longitudinal braking performance. This is followed by a critical analysis of how integrated control architectures resolve the inherent conflicts between them. The analysis reveals a clear trajectory from independent control loops to intelligent, context-aware coordination. It further identifies a paradigm shift from the conventional goal of merely maintaining stability toward proactively managing stability boundaries to enhance system resilience. Furthermore, this review highlights the growing integration with high-level motion planning in automated driving. By synthesizing the current knowledge and mapping future directions toward deeply integrated, intelligent control systems, it serves as both a reference for researchers and a design guide for engineers aiming to unlock the full potential of the distributed drive paradigm. Full article

This study provides a comparison between the impact of two gas fuels, compressed natural gas (CNG) and hydrogen (H₂), on the exhaust emissions of a single-cylinder diesel engine operating in dual-fuel mode. The analysis is conducted with a constant and maximum achieved gas-to-total-fuel ratio (K = 20% and K = max) under varying load conditions, specifically at an engine speed of 2000 min⁻¹ and brake mean effective pressures ranging from 0.2 to 0.43 MPa. The results reveal that H₂ significantly improves the engine’s emissions profile compared to CNG. When H₂ is used as the secondary fuel, reductions in soot, carbon monoxide (CO), carbon dioxide (CO₂), and unburned hydrocarbons (CHs) are more pronounced. However, under certain load conditions, nitrogen oxide (NO_x) emissions are higher with H₂ than with CNG and can even surpass those observed during diesel-only operation. These findings suggest that while H₂ demonstrates superior overall emissions performance, its impact on NO_x emissions under specific conditions requires further optimization to maximize environmental benefits. Full article

Heavy earth-moving machinery is essential for construction, mining, and infrastructure development, but its traditional hydraulic systems, powered by diesel engines, are major contributors to energy losses and inefficiencies. Hydraulic circuits typically account for significant parasitic losses due to throttling, leakage, and low energy recovery, resulting in high fuel consumption and emissions. Recent innovations are transforming hydraulic technology to improve energy efficiency and sustainability. This review highlights advancements such as electro-hydraulic actuators, independent metering systems, and digital hydraulics, which enable precise flow control and minimize throttling losses. The integration of energy recovery systems, including hydraulic accumulators and hybrid architectures, further enhances efficiency by capturing and reusing energy during braking and lowering operations. Additionally, the adoption of smart sensors, predictive analytics, and advanced control algorithms enables real-time optimization of hydraulic performance, reducing idle losses and improving overall system responsiveness. Emerging trends such as fluid power electrification, compact high-pressure components, and the use of eco-friendly hydraulic fluids are also discussed. By synthesizing current research and industrial practices, this paper provides insights into the challenges, opportunities, and future prospects for achieving substantial energy efficiency gains through next-generation hydraulic technologies in heavy earth-moving equipment. Full article

To address the difficulty of balancing trajectory-tracking accuracy and yaw stability for distributed-drive four-axle heavy trucks under high-speed and large-curvature cornering conditions, this paper proposes a hierarchical cooperative control strategy. The upper layer employs Sliding Mode Control (SMC) to achieve precise trajectory tracking, while the lower layer integrates a sliding-mode-based Direct Yaw Moment Control (DYC) and a differential braking allocation strategy to enhance vehicle stability. TruckSim–Simulink co-simulation results demonstrate that, under large-curvature scenarios such as S-shaped paths, sharp lane changes, and single-lane transitions, the proposed strategy outperforms the conventional SMC method. Specifically, the maximum lateral deviation is reduced by 19.23–23.02%, the peak heading angle error decreases from 5.3° to 3.5°, the maximum yaw rate drops from 12.6°/s to 4.6°/s (a 63.49% reduction), and the peak sideslip angle at the vehicle’s center of mass converges from 4.6° to 3.8° (a 17.39% decrease). The results indicate that the proposed strategy achieves coordinated optimization of trajectory tracking and yaw stability under high-speed, large-curvature cornering conditions, providing both theoretical support and engineering value for high-dynamic control of distributed-drive heavy trucks. Full article

The decarbonization of transport demands efficient, low-carbon alternatives to conventional fuels, particularly in regions where full electrification remains constrained. This study investigates the retrofitting of a 1.3 L Geely MR479Q spark-ignition engine for hydrogen operation, combining experimental measurements and one-dimensional numerical simulations in GT-SUITE. The baseline gasoline model was experimentally validated in 12 operating conditions and extended to the full map. In addition, the fuel was changed in the numerical model, and evaluations of hydrogen combustion through predictive sub-models considering mixture formation and pressure-rise limits were performed. Results show that the hydrogen engine operates stably within a wide air–fuel ratio window (λ = 1.0–2.7), with brake thermal efficiencies peaking at approximately 29%, surpassing gasoline operation by up to 5% in the mid-load range. However, port fuel injections cause a reduction in volumetric efficiency and maximum power output due to air displacement, a limitation that could be mitigated by adopting direct injection. A practical hydrogen conversion kit was defined—including injectors, cold-type spark plugs, electronic throttle, and programmable ECU—and the operational cost was analyzed. Economic parity with gasoline is achieved when hydrogen prices fall below ~6 USD kg⁻¹, aligning with near-term green-hydrogen projections. Overall, the results confirm that predictive numerical calibration can effectively support retrofit design, enabling efficient, low-emission combustion systems for sustainable transport transitions. Full article

Reducing the fuel consumption of tractors has consistently been a critical challenge that the agricultural machinery industry must address. To investigate the energy consumption during the plowing process of tractors and enhance their economic efficiency, this study conducted comparative experiments under varying plowing speeds and depths. In this experiment, the CAN bus protocol was utilized for the collection of engine operational data, such as rotational speed and fuel flow. A GPS positioning system was adopted to measure the plowing speed of the tractor and combined with the data from the tractor coasting test, and then the energy consumption for operating the plow was determined. In addition, a tension sensor was installed on the three-point hitch to measure the horizontal pull force exerted by the five-share plow during plowing, thereby facilitating the calculation of the energy consumption of agricultural machinery. The findings indicate that when the tractor’s plowing speed is maintained at 5.7 km/h, both the average fuel consumption and the fuel consumption per unit area increase as the plowing depth increases. If the plowing depth is fixed at 23 cm, the average fuel consumption rises with an increase in plowing speed, whereas the fuel consumption per unit area decreases. The experimental data show that during the actual tillage operation of the tractor, the brake thermal efficiency of diesel engines ranges from 21.76% to 28.57%. The energy consumed by agricultural implements accounts for only 11.79% to 17.04% of the total fuel energy. The energy consumed in operating the tractor-drawn plow accounts for merely 7.87% to 13.66% of the diesel engine output energy. Approximately 23.24% to 38.69% of the effective power of the diesel engine is lost during the transmission process. This study provides valuable insights for optimizing the performance of tractors during operation. Full article

This study presents the experimental and modelling investigation of the performance of an SI methanol marine engine operating under lean conditions. The effects of spark timing and excess air ratio on combustion characteristics, engine performance, and emissions are explored. Multiple machine learning models, including Support Vector Machines (SVM), Artificial Neural Network (ANN), LightGBM, and Random Forest (RF), are employed to predict the engine performance and emission characteristics. Experimental results show that as spark timing advances, the combustion phase advances, with the burn duration being extended. When the excess air ratio is less than 1.35, there exists an optimal spark timing, corresponding to a maximum brake thermal efficiency. The optimal spark timing exhibits an advancing tendency along with increasing excess air ratio. HC emission is primarily determined by the excess air ratio and shows no significant variation under the different spark timings. NO_x emission is initially increased and then decreased with advancing spark timing. Compared with ANN, LightGBM, and RF, SVM demonstrates a superior predictive accuracy, with R² values for engine performance exceeding 0.98 and R² values for emissions above 0.92. Full article

Using hydrogen in compression-ignition internal combustion engines can reduce pollutant emissions and improve performance by enabling faster and more complete combustion. However, it is essential to determine the optimal injection timing and duration for both hydrogen and conventional fuels. These factors are critical in engine modeling analysis. This study aimed to analyze pollutant emissions, combustion, and engine performance with oxyhydrogen fumigation applied to an instrumented Ricardo E6 engine running on diesel fuel. This analysis, necessary for developing a new predictive combustion model, was calibrated with experimental data in the Gamma Technologies Suite (GTS) simulator. The results show four main effects when increasing the oxyhydrogen flow rate from 0 to 2.8 L per minute (LPM), at an indicated mean effective pressure (IMEP) of 5.3 bar and a speed of 1500 RPM: (I) NO_x levels increased by up to 6%, (II) CO₂ levels decreased by 8%, (III) combustion durations remained relatively stable, and (IV) brake specific fuel consumption decreased by 8%. Overall, adding hydrogen to the intake flow of the compression-ignition engine reduced CO₂ emissions and enhanced indicated thermal efficiency. Full article

The traditional ground taxiing method of aircraft has the drawbacks of low efficiency and excessive fuel consumption. In this paper, an aircraft engine-off taxi towing system (AEOTTS) is proposed to provide high-speed traction for the aircraft throughout the entire ground movement. This will be a more efficient intelligent taxiing mode for aircraft. However, the new braking control strategy for the AEOTTS under complex conditions is not yet mature. Based on the motion and mechanical symmetry of the AEOTTS and combined with the contact model of the pick-up and holding system (PUHS), a coupling dynamic model of the AEOTTS is established. On this basis, a state estimator of the AEOTTS is established using the unambiguous Kalman filtering (UKF) method. The follow-up braking control system of the AEOTTS is constructed with the goal of minimizing the towing force on the aircraft’s nose landing gear (NLG), combined with the optimization of braking force distribution and the fuzzy PID control method. By comparing the braking performance of three follow-up braking control systems under wet runway conditions and runway unevenness conditions, the results show that compared with the other two control methods, the follow-up braking control system proposed in this paper can effectively reduce the towing force on the aircraft’s NLG and the braking distance of the AEOTTS, ensuring the safety of the taxiing and traction braking process. Full article

As a core safety component in the hydraulic system of CNC stretching pads, the safety locking valve undertakes precise stamping position maintenance and emergency braking protection; its performance dictates the hydraulic system’s operational stability. Existing ones induce hydraulic oil volume dynamic changes during opening/closing, significantly affecting blank holder force control. To solve this, its structure is innovatively optimized. Based on the CFD method, a dynamic calculation framework integrating unsteady flow characteristics and structural motion characteristics has been constructed, realizing accurate simulation research on the dynamic characteristics of the safety locking valve. Through simulation analysis, the distribution law of the internal flow field during the transient opening and closing process of the locking valve has been thoroughly explored, the distribution mechanism of the transient flow field has been systematically revealed, and finally, the fluid regulation characteristic parameters of the safety locking valve have been obtained, providing an important theoretical basis for subsequent engineering applications. Full article

In 2023, the bicycle industry in Taiwan reached a historic high. However, concerns about carbon emissions persist, particularly during the material acquisition and manufacturing stages of bicycle production. This study utilizes the Life Cycle Assessment (LCA) method, using SimaPro 9.5 for cradle-to-gate carbon emission data analysis. This study thoroughly examines the complete life cycle of a bicycle brake cable product through a carbon reduction evaluation tool, identifying carbon hotspots in the product’s life cycle. The data reveals that packaging accounts for the highest proportion of factory carbon emissions in the brake cable product analysis (34.42%), followed by the product’s casing (30.60%), with the leading materials being metal, plastic, and paper. Throughout the cradle-to-gate process, we collaborated with product developers to utilize the LCA carbon reduction evaluation tool to analyze the life cycle of the brake cable product. By aligning market and development needs, we supported manufacturers in identifying additional carbon reduction strategies at the material selection, mechanical design, and manufacturing process stages. These strategies include using natural raw materials, reducing packaging volume, developing lightweight products, and investing in integrated equipment. By implementing these measures, companies can reduce the product’s carbon footprint and enhance resource efficiency during production. This assessment tool serves as a communication bridge between designers and engineers, translating LCA quantitative data into references for design and management decision-making. It also functions as a simplified analytical tool for SMEs to conduct preliminary diagnosis of carbon emission hotspots and plan improvement directions, particularly suitable for manufacturers lacking consulting resources and carbon inventory capabilities. The research findings not only help companies integrate carbon reduction thinking early in product development, forming a closed-loop system of quantitative analysis and design actions, but also provide concrete references for Taiwan’s bicycle industry to promote supply chain collaboration, achieve green transformation, and meet global carbon reduction goals. Full article

The wheel–rail friction coefficient is a critical factor influencing train traction and braking performance. Low-adhesion conditions not only limit the enhancement of railway transport capacity but are also the primary cause of surface damage such as scratches, delamination, and flat spots. This study employs femtosecond laser technology to fabricate wavy groove textures on U75V rail surfaces, systematically investigating the effects of the wavy angle and texture area ratio on friction enhancement under various medium conditions. Findings indicate that parameter-optimized textured surfaces not only significantly increase the coefficient of friction but also exhibit superior wear resistance, vibration damping, and noise reduction properties. The optimally designed wavy textured surface achieves significant friction enhancement under water conditions. Among the tested configurations, the surface with parameters θ = 150°@η = 30% demonstrated the most pronounced friction enhancement, achieving a coefficient of friction as high as 0.57—a 42.5% increase compared to the non-textured surface (NTS). This enhancement is attributed to the unique hydrophilic and anisotropic characteristics of the textured surface, where droplets tend to spread perpendicular to the sliding direction, thereby hindering the formation of a continuous lubricating film as a third body. Analysis of friction vibration signals reveals that textured surfaces exhibit lower vibration signal amplitudes and richer frequency components. Furthermore, comparison of Stribeck curves under different lubrication regimes for the θ = 150°@η = 30% specimen and NTS indicated an overall upward shift in the curve for the textured sample. The amplitude, energy, and wear extent of the textured surface consistently decreased across boundary lubrication, hydrodynamic lubrication, and mixed lubrication regimes. These findings provide crucial theoretical insights and technical guidance for addressing low-adhesion issues at the wheel–rail interface, offering significant potential to enhance wheel–rail adhesion characteristics in engineering applications. Full article

With the increasing global demand for environmental protection and sustainable energy utilization, methanol, as a clean and renewable fuel, has become a research focus in the field of marine engines. However, its application in compression ignition engines faces bottlenecks such as low combustion efficiency and poor stability. Taking the L23/30H marine diesel engine as the research object, this paper establishes a combustion simulation model for a methanol/diesel dual-fuel direct-injection engine. The reliability of the model is ensured through grid independence verification and model calibration, and a coupled chemical reaction kinetic mechanism containing 126 species and 711 elementary reactions is constructed. A systematic study is conducted on the effects of injection strategies, including fuel operating modes, spray development patterns, injection intervals, and injection timing, on combustion characteristics. The results show that under the optimized injection strategy (vertical cross spray + synchronous injection) proposed in this study and operating conditions with a high methanol substitution ratio, the combustion efficiency, dynamic performance, and soot emission control effect of the dual-fuel mode are superior to those of the pure diesel mode. Simulation results show that the combined strategy of vertical cross injection and synchronous injection can significantly increase the indicated thermal efficiency (ITE) by 3.2%, reduce the brake specific fuel consumption (BSFC) by approximately 4.5%, advance the peak heat release by 2 °CA, and remarkably improve the combustion efficiency, while earlier injection timing is beneficial to air–fuel mixing. Further comparison of combustion and emission characteristics under different boundary conditions such as methanol energy ratios and injection pressures reveals that increasing methanol injection pressure, compression ratio, and initial pressure can improve combustion uniformity and reduce soot emissions, but NO_x emissions increase, which requires the coordination of after-treatment technologies. Through the comprehensive optimization of multiple parameters, efficient and clean combustion under a high methanol substitution rate is achieved. This paper provides theoretical support and practical guidance for the technological development of marine methanol dual-fuel engines. In the future, industrial applications can be promoted by combining actual engine tests and after-treatment technologies. Full article