Search Results (3,537)

Typhoon-induced waves significantly threaten marine transportation and safety, often leading to catastrophic marine disasters. Accurate wave simulations are vital for effective disaster prevention. However, traditional studies have primarily focused on significant wave height (SWH) and heavily relied on resource-intensive numerical simulations while often neglecting wave spectra, which are essential for understanding the distribution of wave energy across various frequencies and directions. Addressing this gap, our study introduces an LSTM–Self Attention–Dense model that comprehensively simulates both SWH and wave frequency spectra. The model was rigorously trained and validated on three years of global typhoon data and exhibited accuracy in forecasting both SWH and wave spectra. Furthermore, our analysis identifies optimal input data windows and underscores wind speed and central pressure as critical predictive features. This novel approach not only enhances marine risk assessment but also offers a swift and efficient forecasting tool for managing extreme weather events, thereby contributing to the advancement of disaster management strategies. Full article

The deployment of the HY-2B/2C/2D satellite constellation marks a significant advancement in China’s marine dynamic environmental satellite program, forming a robust three-satellite network. All satellites are equipped with the “HY2_Receiver”, an indigenous technological achievement. Precise orbit determination using this receiver is critical for monitoring dynamic oceanic parameters such as sea surface wind fields and heights. This study presents a detailed analysis and comparison of the GPS data quality from the HY-2B/2C/2D satellites, emphasizing the impact of phase center variation (PCV) model corrections on orbit accuracy, with a particular focus on high-precision reduced-dynamic orbit determination. The experimental results demonstrate that the GPS data from the satellites exhibit consistent satellite visibility and minimal multipath errors, confirming the reliability and stability of the receivers. Incorporating PCV model corrections significantly enhances orbit accuracy, achieving improvements of approximately 0.3 cm. Compared to DORIS-derived orbits from the Centre National d’Études Spatiales (CNES), the GPS-derived reduced-dynamic orbits consistently reach radial accuracies of 1.5 cm and three-dimensional accuracies of 3 cm. Furthermore, validation using Satellite Laser Ranging (SLR) data confirms orbit accuracies better than 3.5 cm, with 3D root mean square (RMS) accuracies exceeding 3 cm in the radial (R), along-track (T), and cross-track (N) directions. Notably, the orbit determination accuracy remains consistent across all satellites within the HY-2B/2C/2D constellation. This comprehensive analysis highlights the consistent and reliable performance of the indigenous “HY2_Receiver” in supporting high-precision orbit determination for the HY-2B/2C/2D constellation, demonstrating its capability to meet the rigorous demands of marine dynamic environmental monitoring. Full article

This paper proposes an E-core outer-rotor hybrid-excitation flux switching (OR-HEFS) machine for in-wheel direct driving application. According to the general air gap field modulation theory, the magneto-motive force (MMF) permeance model was established to investigate the air gap flux density, and then the torque generation, the flux regulation principle, and the excitation-winding-induced voltage of the E-core OR-HEFS machine were analyzed. To characterize the output performances, the influence of the design parameters was investigated for the E-core OR-HEFS machine, including the split ratio, stator tooth arc, PM arc, fault-tolerant tooth arc, rotor tooth arc, stator yoke width and rotor yoke width. The performances contained the output torque, torque ripple, flux regulation ratio, and the excitation-winding-induced voltage. On this basis, the aforementioned four performances were optimized by means of the non-dominated sorting genetic algorithm II (NSGA-II). Based on the optimization result, a prototype was manufactured and tested to verify the whole investigation of this paper. Full article

Old city courtyards are crucial elements of Beijing’s ancient capital. However, existing ones face heating problems. This study focuses on renovated and original-style courtyards. By employing ENVI-met and DeST software, we comprehensively analyzed the courtyard’s thermal environment, ventilation, indoor conditions, and energy consumption. Findings reveal that both types have thermal discomfort. Original courtyards are colder in winter and hotter in summer due to wind and radiation. They possess better ventilation but a higher winter heating load. Both require winter heating, with the original ones having a larger unit area load because of envelope heat loss and ventilation differences. Their direct electric heating consumptions, 187.6 kWh/m² and 229.6 kWh/m², respectively, surpass ordinary residences. This study defines issues for future green and low-carbon courtyard work. Full article

Recently, the rapid proliferation of eco-friendly mobility solutions has driven an increasing demand for high-efficiency, high-power, compact, and reliable traction motors. In the eco-friendly mobility sector, electric mobility commonly employs Interior Permanent Magnet Synchronous Motors (IPMSMs) due to their high efficiency, high power, and compact size. However, ensuring reliability requires effective fault diagnosis. Among various faults, eccentricity in traction motors can degrade performance characteristics, including vibration, noise, and torque precision, thereby impairing driving performance. This paper proposes a novel winding method for Variable Reluctance (VR) resolvers and introduces a fault diagnosis approach for eccentricity using Finite Element Method (FEM) analysis. By employing this novel winding method, the direction of eccentricity occurrence can be effectively identified. Additionally, this method demonstrates robustness against defects, such as open-circuit faults, compared to a conventional winding method. Therefore, the proposed winding method contributes to improving the reliability and stability of IPMSMs through fault diagnosis and ensures robustness against open-circuit faults in the VR resolver. Full article

This work presents the design and implementation of an emergency sound detection and localization system, specifically for sirens and horns, aimed at enhancing road safety in automotive environments. The system integrates specialized hardware and advanced artificial intelligence algorithms to function effectively in complex acoustic conditions, such as urban traffic and environmental noise. It introduces an aerodynamic structure designed to mitigate wind noise and vibrations in microphones, ensuring high-quality audio capture. In terms of analysis through artificial intelligence, the system utilizes transformer-based architecture and convolutional neural networks (such as residual networks and U-NET) to detect, localize, clean, and analyze nearby sounds. Additionally, it operates in real-time through sliding windows, providing the driver with accurate visual information about the direction, proximity, and trajectory of the emergency sound. Experimental results demonstrate high accuracy in both controlled and real-world conditions, with a detection accuracy of 98.86% for simulated data and 97.5% for real-world measurements, and localization with an average error of 5.12° in simulations and 10.30° in real-world measurements. These results highlight the effectiveness of the proposed approach for integration into driver assistance systems and its potential to improve road safety. Full article

The integration of photovoltaic (PV) systems into tensioned membrane structures presents a significant advancement for sustainable applications in the built environment. However, a critical technical challenge remains in the substantial strains induced by external loads, which can compromise both PV efficiency and the structural integrity of the membrane. Current design methodologies prioritize stress, deflection, and ponding analysis of tensioned membranes. Strain behavior of whole structures, a key factor for ensuring long-term performance and compatibility of PV-integrated membranes, has been largely overlooked. This study addresses this gap by examining the whole membrane structure designed for PV integration, with the aim of optimizing the membrane to provide suitable conditions for efficient energy transfer while minimizing membrane strains. For this purpose, it provides a comprehensive strain analysis for full-scale hyperbolic paraboloid (hypar) membrane structures under various design parameters and external loads. Employing the Finite Element Method (FEM) via Sofistik software, the research examines the relationship between load type, geometry, material properties, and patterning direction of membranes to understand their performance under operational conditions. The findings reveal that strain behavior in tensioned membrane structures is strictly influenced by these parameters. Wind loads generate significantly higher strain values compared to snow loads, with positive strains nearly doubling and negative strains tripling in some configurations. Larger structure sizes and increased curvature amplify strain magnitudes, particularly in parallel patterning, whereas diagonal patterning consistently reduces strain levels. High tensile-strength materials and optimized prestress further reduce strains, although edge type has minimal influence. By systematically analyzing these aspects, this study provides practical design guidelines for enhancing the structural and operational efficiency of PV-integrated tensioned membrane structures in the built environment. Full article

This paper presents a quaternion-based robust sliding-mode controller for quadrotors operating under significant wind disturbances. The proposed control method improves the reliability and efficiency of quadrotor control by eliminating the singularity problem inherent in the Euler angle method. The quadrotor dynamics and wind environment are modeled, and dynamic analysis is performed via numerical simulation. A realistic wind model is used, similar to a combination of deterministic and statistical models. The Lyapunov stability theory is utilized to prove the convergence and stability of the proposed control system. The simulation results demonstrate that the quaternion-based controller enables the quadrotor to follow the desired path and remain stable, even under external wind disturbances. Specifically, both position and attitude converge to the desired values within 10 s, demonstrating stable performance despite the challenging wind disturbances in both scenarios. Scenario 1 features turbulence with an average wind speed of 12 m/s and changing wind directions, while Scenario 2 models an environment with wind speeds that change abruptly and discretely over time, coupled with temporal variations in wind direction. Additionally, a comparative analysis with the conventional PD controller highlights the superior performance of the proposed RSMC controller in terms of trajectory tracking, stability, and energy efficiency. The rotor speeds remain within a reasonable and hardware-feasible range, ensuring practical applicability. Full article

The offshore wind power sector has witnessed exponential growth over the past decade, with large-scale offshore wind farms grappling with the challenge of elevated construction and maintenance expenses. Given that the collector system constitutes a substantial part of the investment cost in wind farms, the design and optimization of this system are pivotal to enhancing the economic viability of offshore wind farms. A thorough examination of collector system design and optimization methodologies is essential to elucidate the critical aspects of collector system design and to assess the comparative merits and drawbacks of various optimization techniques, thereby facilitating the development of collector systems that offer superior economic performance and heightened reliability. This paper conducts a review of the evolving trends in collector system research, with a particular emphasis on topology optimization models and algorithms. It juxtaposes the economic and reliability aspects of collector systems with varying topologies and voltage levels. Building on this foundation, the paper delves into the optimization objectives and variables within optimization models. Furthermore, it provides a comprehensive overview and synthesis of AI-driven optimization algorithms employed to address the optimization challenges inherent in offshore wind farm collector systems. The paper concludes by summarizing the existing research limitations pertaining to offshore wind farm collector systems and proposes innovative directions for future investigative endeavors. The overarching goal of this paper is to enhance the comprehension of offshore wind farm collector system design and optimization through a systematic analysis, thereby fostering the continued advancement of offshore wind power technology. Full article

Yaw errors occur in wind turbines either during the installation stage or because of the aging of devices. It reduces the wind speed in the rotor axial direction and increases the structural loads in the lateral direction. Diagnosing yaw error rapidly and accurately is crucial for avoiding the introduced under-performance. In this review paper, we first introduce the fundamental concepts and principles of wind turbine yaw control strategies, and we discuss two types of yaw errors (i.e., the static yaw error and the dynamic yaw error) with their corresponding causes. Subsequently, we outline the existing yaw error diagnostic methods, which are based on the LiDAR (light detection and ranging) data, the SCADA (supervisory control and data acquisition) data, or a combination of the two, and we discuss the advantages and disadvantages of various methods. At last, we emphasize that the diagnostic performance can be improved via the combination of the LiDAR data and the SCADA data, and it benefits from an in-depth understanding of the salient features and influential factors associated with the yaw error. Meanwhile, the potential of intelligent clusters and digital twins for detecting yaw errors is discussed. Full article

A skin friction sensor is a three-dimensional MEMS sensor specially designed for measuring the skin friction of hypersonic vehicle models. The accuracy of skin friction measurement under hypersonic laminar flow conditions is closely related to the fabrication and micro-assembly accuracy of MEMS skin friction sensors. In order to achieve accurate skin friction measurement, high-precision linear laser scanning ranging, multi-axis precision drive, and 3D reconstruction algorithms are investigated; a MEMS skin friction sensor micro-assembly height error measurement system is developed; and the MEMS skin friction sensor micro-assembly height error control method is carried out. The results show that the micro-assembly height error measurement of MEMS skin friction sensors achieves an accuracy of up to 2 μm. The height errors of the MEMS skin friction sensor were controlled within −8 μm to +10 μm after error control. The angular errors were controlled within the range of 0.05–0.25°, significantly improving micro-assembly accuracy in the height direction of the MEMS skin friction sensor. The results of hypersonic wind tunnel tests indicate that the deviation in the accuracy of the MEMS skin friction sensors after applying height error control is about 5%, and the deviation from the theoretical value is 8.51%, which indicates that height error control lays the foundation for improving the accuracy of skin friction measurement under hypersonic conditions. Full article

Small uncrewed aerial systems (sUASs) can be used to quantify emissions of greenhouse and other gases, providing flexibility in quantifying these emissions from a multitude of sources, including oil and gas infrastructure, volcano plumes, wildfire emissions, and natural sources. However, sUAS-based emission estimates are sensitive to the accuracy of wind speed and direction measurements. In this study, we examined how filtering and correcting sUAS-based wind measurements affects data accuracy by comparing data from a miniature ultrasonic anemometer mounted on a sUAS in a joust configuration to highly accurate wind data taken from a nearby eddy covariance flux tower (aka the Tower). These corrections had a small effect on wind speed error, but reduced wind direction errors from 50° to >120° to 20–30°. A concurrent experiment examining the amount of error due to the sUAS and the Tower not being co-located showed that the impact of this separation was 0.16–0.21 ms−1, a small influence on wind speed errors. Lower wind speed errors were correlated with lower turbulence intensity and higher relative wind speeds. There were also some loose trends in diminished wind direction errors at higher relative wind speeds. Therefore, to improve the quality of sUAS-based wind measurements, our study suggested that flight planning consider optimizing conditions that can lower turbulence intensity and maximize relative wind speeds as well as include post-flight corrections. Full article

During the service period, the offshore wind turbine foundation mainly bears the wind load from the upper structure and the periodic loads such as wave load and sea currents from the lower structure. Long-term cyclic loads have an important impact on the cumulative deformation, foundation stiffness changes, and horizontal ultimate bearing capacity of the offshore wind turbine bucket foundation. This paper conducts cyclic loading tests on mono-bucket foundations under unidirectional and multidirectional cyclic loading conditions based on the multidirectional intelligent cyclic loading system of offshore wind turbine foundations and analyzes the cumulative effects of the loading direction, vertical load, and drainage status on the mono-bucket foundation during the cyclic loading process, effects of rotation angle, cyclic stiffness, and monotonic bearing capacity of foundation after cycles. The research results show that multidirectional cyclic loading significantly reduces the cyclic cumulative rotation angle of the mono-bucket foundation, and the maximum reduction rate can reach more than 50%. After unidirectional and multidirectional cyclic loading, the bearing capacity of the bucket foundation can be increased by up to 30% and 20%, respectively. At the same time, this paper proposes calculation formulas for vertical load, number of cyclic loading, and normalized cumulative rotation and establishes a calculation method for vertical load and bearing capacity of the foundation after cycles. Full article

This study provides a comprehensive evaluation of the vertical accuracy of ERA5 reanalysis data for boundary layer height and key meteorological variables, based on high-precision observational data from Baotou, located on the Mongolian Plateau, during the winter (January–March) and summer (July–August) months of 2021. Results indicate that ERA5 exhibits significant biases in horizontal wind speed, with deviations ranging from −5 to 8 m/s at 50 m, primarily driven by sandstorms in winter and convective weather in summer. The most pronounced errors occur below 500 m. Vertical wind speeds are consistently underestimated in both seasons, with biases reaching up to 1 m/s, particularly during active summer convection. ERA5 also struggles to reproduce low-level wind directions accurately. In winter, correlation coefficients range from 0.43 to 0.64 below 200 m and improve to above 0.7 at 500 m. In summer, correlation coefficients are lower, ranging from 0.3 to 0.5 below 200 m, with reduced accuracy at 500 m compared to winter. Temperature deviations increase above 2000 m, with a relative overestimation of 3% at 3000 m. Relative humidity is generally overestimated by 5–20% between 1000 and 2000 m in winter and by 10–30% in summer. For boundary layer heights, ERA5 overestimates daytime mixed-layer heights by up to 2000 m in summer and 500–800 m in winter. In contrast, ERA5 captures nocturnal stable boundary layer heights well during winter. This comprehensive evaluation of the vertical structure accuracy of ERA5 reanalysis data, conducted in a heavily industrialized city on the Mongolian Plateau, offers essential insights for improving meteorological studies and refining climate models in the region. The findings provide valuable reference data for enhancing weather forecasting and supporting climate change research, particularly in complex terrain areas. Full article

The development of new energy vehicles and road dust removal technologies presents opportunities for constructing urban ventilation systems based on road patterns. However, the impact of road system layouts on pedestrian-level wind environments remains insufficiently understood. This study utilizes the general-purpose CFD software Phoenics to analyze the effects of road orientation, width, density, and intersection configurations on block ventilation. The standard k-ε model and three-dimensional steady-state RANS equations are employed to calculate pedestrian-level mean air age as an indicator of ventilation efficiency. Grid convergence analysis and validation against previous wind tunnel measurements were conducted. Results show that road layouts influence overall ventilation efficiency by affecting airflow volume, direction, and velocity. Optimal ventilation occurs when road orientation aligns with the prevailing wind at 0° or exceeds 70°. Recommended widths for trunk, secondary, and local roads are 46 m, 30 m, and 18 m, respectively. Lower densities of local road systems enhance ventilation, while higher densities of trunk and secondary roads are beneficial. Intersection configurations impact airflow distribution, with windward segments aiding lateral ventilation of side roads. Finally, ventilation design strategies for road systems are proposed, offering potential for leveraging urban road networks to construct efficient ventilation systems. Full article