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Aiming at the voltage fluctuation problem caused by indirectness and uncertainty in new energy power generation system, the backstepping control strategy is firstly applied in electric spring (ES) system, and an ES backstepping control strategy with command filtering is proposed. According to the mathematical model of ES, the controller is designed by backstepping method and command filter is added to solve the computational inflation problem in ES backstepping control. Meanwhile, the error compensation signal is designed, and the stability of the system is verified by the Lyapunov stability theory. The effect of ES on critical load (CL) voltage stabilization is simulated when the grid-side voltage of the new energy power generation system fluctuates, and the sensitivity analysis of different system parameters to the control strategy is discussed in this paper. Compared with traditional proportional integral (PI) control, the dynamic response speed of CL voltage is improved by 0.07 s, while the CL voltage distortion rate is reduced by 31%. In parameter sensitivity analysis, the maximum deviation rate of CL voltage is 0.318%. Meanwhile, the maximum voltage amplitude fluctuation range that it can withstand is increased by 52.9 V. It is verified that the control strategy proposed in this paper has the advantages of fast response, low harmonic content and strong anti-interference ability.

Aiming at the accurate speed tracking control of electric vehicles (EV) driven by permanent magnet synchronous motors (PMSM) under external load torque disturbances, this paper proposes an approach for prescribed performance back-stepping control based on a disturbance observer. Firstly, a controller was designed using the back-stepping technique, and a second-order sliding mode differentiator was introduced to approximate the derivative of the virtual control law, which can solve the "differential explosion" problem in traditional back-stepping control techniques. Secondly, in order to reduce the influence of motor load disturbances in the driving process of EV, a novel disturbance observer was proposed, bolstering the anti-interference capability of system. In addition, to achieve the preset high transient and steady-state speed tracking performance, a prescribed performance control strategy was incorporated to guarantee tracking errors within predefined boundaries. Finally, the Lyapunov function was utilized to verify the system stability. The simulation results showed that, compared with traditional PI control, the designed controller significantly increased motor speed tracking precision by more than 5 times, demonstrating a superior speed tracking performance and enhanced anti-interference capability.

The upper airway cough syndrome (UACS) is a common chronic cough in children, and it has gradually increased in recent years. Chinese medicine believes that the main location of the disease is nasopharynx, which is closely related to the spleen and kidney. The most common pathological factor is wind, phlegm, deficiency and stasis, and the basic pathogenesis is upward inversion of lung Qi. Chinese medicine treatment mainly focuses on the combination of disease and syndrome differentiation, the combination of body and syndrome differentiation, staged Chinese medicine differentiation and treatment, cold and heat syndrome differentiation, viscera syndrome differentiation, Chinese medicine external treatment and combination of Chinese medicine and western medicine in order to regulate lung Qi. This article mainly elaborates on the differentiation and treatment of Chinese medicine for pediatric UACS, as well as its clinical treatment effects to provide some reference for further research on the treatment of pediatric UACS with Chinese medicine.

The hygrothermal aging model, based on Fick's second law of diffusion, characterizes the degradation of engineering constants in T700 carbon fiber/epoxy resin composites. It focuses on changes in the tensile modulus, shear modulus, and transverse Poisson's ratio due to moisture absorption and temperature variations. The model validates through mass change observations before and after seawater immersion, along with surface morphology assessments and tensile experiments. The results reveal that the saturated moisture absorption rate for single-layer laminates in seawater immersion is 0.35%. Short-term seawater immersion at room temperature (≤60 days) does not induce cracks or defects (≥10 μm) on the composite's surface. The composite's modulus decreases as moisture absorption increases, with the longitudinal tensile modulus dropping by an order of 10−5%, while the other engineering constants decrease by an order of 10−3%. The modulus also decreases with rising temperature; the closer the temperature is to the matrix's glass transition, the faster the modulus declines, with the longitudinal tensile modulus decreasing by 0.84%, and the other engineering constants decreasing by 100%. This research provides valuable insights for the engineering applications of composite materials in marine environments. [ABSTRACT FROM AUTHOR]

Infectious diseases, particularly those caused by pathogens and parasites, present significant global health challenges. Despite advancements in medicine, these diseases continue to result in high rates of illness, loss of function, and mortality. The continuous COVID-19 pandemic, stemming from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), highlights the critical necessity for early detection strategies to improve patient outcomes. We present a novel microfluidics platform for the simultaneous detection of proteins (antigens) crucial for SARS-CoV-2 identification: S1, RBD, and NCD. By combining microfluidics with surface-enhanced Raman scattering (SERS), the platform enables highly sensitive and multiplexed detection of viral proteins. Furthermore, it employs an engineered mesoporous gold nanoparticle (mAuNP)-based SERS nanotags to achieve a highly sensitive readout. Demonstrating excellent analytical performance, our platform simultaneously detects three antigens, achieving detection levels as low as 14 pg mL−1, with an RSD of <5.0% (n = 3). Compared to existing approaches, our platform offers critical improvements for SARS-CoV-2-like infectious disease analysis. It provides a multiplex detection system alongside controls, a simple experimental setup, and a single-device-based complete assay platform. The mAuNP-based SERS nanotags eliminate the need for enzymatic amplification, while the portable SERS readout facilitates an on-site detection without sophisticated instrumentation or laboratory requirements. [ABSTRACT FROM AUTHOR]

Highlights In the fiber winding process, the maximum static friction coefficient significantly influences the designable range of non‐geodesic winding trajectories and the behavior of fiber stacking and sliding. To accurately and conveniently measure the maximum static friction coefficient for fiber winding, a method based on semi‐geodesic trajectories was proposed. This method assesses the maximum static friction coefficient between fibers and mandrels, as well as between fibers, without requiring additional component fabrication. Its effectiveness was investigated, and two methods for determining fiber yarn slip were proposed. Additionally, measurement errors and variations in the slip coefficient before and after fiber yarn slip were examined. The research results indicate that the proposed measurement method has an error margin of approximately ±6%. After fiber yarn slip, the slip coefficient gradually decreases along the winding trajectory. The maximum static friction coefficient is independent of both winding speed and winding tension. A method for measuring the maximum static friction coefficient was proposed. Two methods were proposed for determining the slip of fiber yarn. The method allows for direct measurement using the mandrel to be wound. The maximum static friction coefficient between fibers can be measured. [ABSTRACT FROM AUTHOR]

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[Objective] Vehicle detection is critical for urban intelligent transportation. Focusing on small target problems, high-density problems, and motion attribute problems, this study takes traffic surveillance images as input and aims to detect moving vehicles. [Method] Based on the anchor-free CenteNet, a detection method of multi-scale features and dual-source motion perception was proposed. Firstly, coordinate attention was introduced to the multi-scale and global context features of the network's abstraction layer, so as to supplement information in multiple stages and at multiple levels and improve the model's understanding of vehicles and scenes. Secondly, through fuzzy textures representing actual motion features of vehicles and optical flow knowledge representing general motion features of vehicles, the model's perception ability of moving vehicles was constructed. [Result] The experimental data came from the public dataset UA-DETRAC. The mean average precision (mAP) and frames per second (FPS) were used as the evaluation metrics of accuracy and speed. Experiment results show that the mAP and FPS of the proposed method are 70% and 30 frame/s respectively, which have the best balance between speed and accuracy among other compared methods. [Conclusion] It maintains that the proposed method is competent in the task of moving vehicle detection. [ABSTRACT FROM AUTHOR]