Wyniki wyszukiwania - BazTech

1

Analysis of low saliency ratio and torque characteristics of the fractional slot concentrated winding Surface mounted motors

Qiu Hongbo, Wang Dong, Yang Cunxiang, Wang Kun

Archives of Electrical Engineering

|

2024

|

Vol. 73, nr 1

165--182

EN

In recent years, fractional slot concentrated winding permanent magnet synchronous motors (FSCW PMSMs) have become a hotspot in the research field. Due to the unique inductance characteristics of the FSCW PMSM, a fast and accurate calculation of the d/q-axis inductance and saliency ratio is necessary. In this paper, a method is proposed to calculate the d/q-axis reactance of the FSCW SPMSM, which constructs the equivalent magnetic circuit model of the d/q-axis armature reaction flux separately, and the saliency ratio characteristics of the FSCW SPMSM were demonstrated. In addition, to meet the high requirements of the modern industries, especially in servo systems, accurate consideration of the effect of stator resistance on torque and electromagnetic performance is important and more applicable. According to the relationship between the vector parameter, the explicit expression of the d/q-axis currents that consider the stator resistance is obtained, and the prediction of load angle at maximum electromagnetic torque is achieved. Then, combined with the finite element method, the influence mechanism of stator resistance on the motor steady-state performance is revealed. Finally, the experimental data are compared with the calculation data, and the correctness of the models and analysis was verified.

2

Automated detection of abnormal respiratory sound from electronic stethoscope and mobile phone using MobileNetV2

Liao Ximing, Wu Yin, Jiang Nana, Sun Jiaxing, Xu Wujian, Gao Shaoyong, Wang Jun, Li Ting, Wang Kun, Li Qiang

Biocybernetics and Biomedical Engineering

|

2023

|

Vol. 43, no. 4

763--775

EN

Auscultation, a traditional clinical examination method using a stethoscope to quickly assess airway abnormalities, remains valuable due to its real-time, non-invasive, and easy-to-perform nature. Recent advancements in computerized respiratory sound analysis (CRSA) have provided a quantifiable approach for recording, editing, and comparing respiratory sounds, also enabling the training of artificial intelligence models to fully excavate the potential of auscultation. However, existing sound analysis models often require complex computations, leading to prolonged processing times and high calculation and memory requirements. Moreover, the limited diversity and scope of available databases limits reproducibility and robustness, mainly relying on small sample datasets primarily collected from Caucasians. In order to overcome these limitations, we developed a new Chinese adult respiratory sound database, LD-DF RSdb, using an electronic stethoscope and mobile phone. By enrolling 145 participants, 9,584 high quality recordings were collected, containing 6,435 normal sounds, 2,782 crackles, 208 wheezes, and 159 combined sounds. Subsequently, we utilized a lightweight neural network architecture, MobileNetV2, for automated categorization of the four types of respiratory sounds, achieving an appreciable overall performance with an AUC of 0.8923. This study demonstrates the feasibility and potential of using mobile phones, electronic stethoscopes, and MobileNetV2 in CRSA. The proposed method offers a convenient and promising approach to enhance overall respiratory disease management and may help address healthcare resource disparities.

3

An analysis of the impact of e-commerce supply chain collaboration on the ecological environment in Central Plain

Wang Kun, Zhang Mengze

Ecological Chemistry and Engineering. S

|

2022

|

Vol. 29, nr 3

333--346

EN

In recent years, the ecological environment has been severely damaged and has evolved into a problem threatening human health due to the construction of the ecological environment. Therefore, studying the eco-environmental (ecological environment) issues in the process of the new eco-environment is of great significance to the comprehensive development of the region. The basic research framework of this article is to ask questions, analyse problems and solve problems. With the rise of e-commerce media platforms as the background, we use case studies and in-depth interviews to discuss the characteristics of the ecological crisis of e-commerce media platforms and analyse them in depth. This paper takes the new ecological environment as the research background, selects six major cities in the Central Plains as the research objects, and digs deep to find out the current ecological and environmental problems in the Central Plains. By citing the PSR (Pressure-State-Response) model, we construct the initial pressure and use the factor analysis method to determine the evaluation index model of the 16 sub-indices. Finally, we use the entropy method to standardise the original indicators. We determine the index weights, etc., to analyse the level of the ecological environment of the six cities. At the same time, this article evaluates the ecological environment in the process of the new ecological environment in the Central Plains. First, an evaluation index system is established, and then the evaluation index weight is determined to obtain the order of the ecological environment problems. According to the total score value of ecological environment quality, for different areas, comprehensive ecological environment zoning is proposed so that resources can be better and rationally developed and utilised. The ecological environment of mining areas is protected and improved to the maximum extent. At the same time, the mine ecological environment monitoring work plan is formulated; the construction of ecological restoration is proposed for areas (mine parks, geological parks, forest parks, and ecological parks). Through organisational structure adjustment and overall supply chain optimisation, relevant feasible solutions are proposed, and examples are given to illustrate the optimisation effects; the part summarises the significance of this research and the main existing problems and proposes future research recommendations. In the context of the new ecological environment, analysing the current situation of the ecological environment in the Central Plains, identifying the ecological and environmental problems in the process of the ecological environment, and proposing corresponding solutions based on the problems are conducive to the development of the new ecological environment in the Central Plains.

4

Research on magnetic regulation characteristics of axial-radial flux type permanent magnet synchronous machine

Yang Cunxiang, Wang Kun, Liu Ziyang, Xiong Bin, Zhao Qiang

Archives of Electrical Engineering

|

2022

|

Vol. 71, nr 1

75--90

EN

Due to the fixed rotor magnetic field, the main magnetic flux of conventional permanent magnet synchronous motors (PMSMs) cannot be flexibly adjusted. Recently, the axial-radial flux type permanent magnet synchronous machine (ARFTPMSM) based on the hybrid excitation concept is proposed, which provides a new method for the speed and magnetic field regulations for PMSMs. To analyze the mechanism of magnetic field variation inside the ARFTPMSM, in this paper, three – dimensional finite element models for electromagnetic field calculation of the ARFTPMSM are established. On this basis, the influence of the axial device on the motor is discussed, and the mechanism of flux regulation is explained. By the quantitative calculation of air-gap flux density and the noload back-electromotive force (EMF), the flux regulation capability of the ARFTPMSM is verified. In addition, the effect of the excitation magnetomotive force on the magnetic field harmonics is analyzed combined with the winding theory, and the influence of the axial magneto-motive force (MMF) on the torque fluctuation is obtained. The flux regulation performance of the motor and the validity of the numerical calculation analysis are verified by the experiments.