In this article, the coupling effects of the unbalanced magnetic pull and ball bearing on nonlinear vibration of the three-phase asynchronous motor are investigated with the experimental and ...numerical methods. A test rig of a motor whose rotor supported by ball bearings is used and a 2 degrees of freedom magnetic solid coupling dynamic model of the motor rotor system is presented. The nonlinear dynamic response and spectrum are obtained from experiments and numerical analysis. The numerical results are in good agreement with test data, thus validating the presented model. It is found that the unbalanced magnetic pull and ball bearing forces possess the significantly interactional and nonlinear influences on the rotor dynamic characteristics. Small magnetic pull could impact the nonlinear bearing-rotor system, resulting in remarkable changes in the dynamic characteristics of the system. The effects of rotational speed and the rotor mass eccentricity on dynamic behaviors of the motor are discussed, and the results show that the magnetic pull gradually increases the amplitude of the ball bearing-rotor system, and its effect decreases with the increment of the rotational speed and mass eccentricity.
Abstract
Real-time detection of solar radio bursts is crucial in solar physics research and space weather forecasting. However, current research on the automatic detection of solar radio bursts is ...limited to identifying the presence or absence of solar radio bursts or recognizing only a single type of burst, such as type II or III. Furthermore, existing methods cannot learn spectral and temporal features and often suffer from the drawbacks of large network models, resulting in slow speeds. This paper proposes an automatic recognition and localization method based on a lightweight object detection model for solar radio burst events. We collected observation data from e-CALLISTO and established a data set containing type II, III, IV, and V solar radio bursts. To address the real-time requirements of practical applications and consider the temporal and frequency domain information of spectrogram images, we improved a vision transformer with a self-attention mechanism and adopted a lightweight model for detection. The experimental results demonstrate that our proposed method achieves an average precision at a 50% intersection-over-union threshold of 78.2% and a recall rate of 92% on the established solar radio burst data set. Additionally, the model operates at a detection speed of 54.8 frames s
–1
, where a frame refers to a spectral image with a duration of 15 minutes, enabling efficient automated detection and localization of type II, III, IV, and V solar radio bursts.
Highlight removal is a critical and challenging problem. In view of the complex highlight phenomenon on the surface of smooth liquor bottles in natural scenes, the traditional highlight removal ...algorithms cannot semantically disambiguate between all-white or near-white materials and highlights, and the recent highlight removal algorithms based on deep learning lack flexibility in network architecture, have network training difficulties and have insufficient object applicability. As a result, they cannot accurately locate and remove highlights in the face of some small sample highlight datasets with strong pertinence, which reduces the performance of some tasks. Therefore, this paper proposes a fast highlight removal method combining U2-Net and LaMa. The method consists of two stages. In the first stage, the U2-Net network is used to detect the specular reflection component in the liquor bottle input image and generate the mask map for the highlight area in batches. In the second stage, the liquor bottle input image and the mask map generated by the U2-Net are input to the LaMa network, and the surface highlights of the smooth liquor bottle are removed by relying on the powerful image inpainting performance of LaMa. Experiments on our self-made liquor bottle surface highlight dataset showed that this method outperformed other advanced methods in highlight detection and removal.
The magnetic pull, bearing forces, and operating temperature, as important factors affecting motor performance, actually act together on the electric motor. In this study, the magnetic-solid-thermal ...coupling rotordynamic behaviors of a three-phase asynchronous motor are investigated via experiments and numerical analysis. A motor test platform controlled by a variable frequency converter is offered, and the experiments under multiworking conditions are carried out to explore the rotordynamic characteristics of the motor system. A rotordynamic modeling method of the magnetic-solid-thermal coupling system is presented for analyzing the coupling effect of the unbalanced magnetic pull (UMP), nonlinear ball bearing forces (NBB), and operating temperature on the motor rotordynamic behaviors. All of the predicted results coincide well with the experimental data to validate the presented model. Through experiments and numerical analysis, it is shown that the interaction of magnetic, structural, and thermal fields plays a significant role in the nonlinear vibration of the motor rotor. UMP, even with slight amplitudes at low rotating speeds, can induce a remarkable impact on the dynamic characteristics of the system on account of the nonlinear effect of ball bearing forces. The combined action of UMP and NBB on the thermal effect is more notable than that of single action. The effect of the unbalanced load gradually decreases with the increase of the temperature. The experimental and numerical results indicate that the magnetic-solid-thermal coupling influence is a noticeable issue in the optimum design, failure diagnosis, and operation maintenance of motor systems.
Aqueous zinc‐ion batteries (AZIBs) offer promising prospects for large‐scale energy storage due to their inherent abundance and safety features. However, the growth of zinc dendrites remains a ...primary obstacle to the practical industrialization of AZIBs, especially under harsh conditions of high current densities and elevated temperatures. To address this issue, a Janus separator with an exceptionally ultrathin thickness of 29 µm is developed. This Janus separator features the bacterial cellulose (BC) layer on one side and Ag nanowires/bacterial cellulose (AgNWs/BC) layer on the other side. High zincophilic property and excellent electric/thermal conductivity of AgNWs make them ideal for serving as an ion pump to accelerate Zn2+ transport in the electrolyte, resulting in greatly improved Zn2+ conductivity, deposition of homogeneous Zn nuclei, and dendrite‐free Zn. Consequently, the Zn||Zn symmetrical cells with the Janus separator exhibit a stable cycle life of over 1000 h under 80 mA cm−2 and are sustained for over 600 h at 10 mA cm−2 under 50 °C. Further, the Janus separator enables excellent cycling stability in AZIBs, aqueous zinc‐ion capacitors (AZICs), and scaled‐up flexible soft‐packaged batteries. This study demonstrates the potential of functional separators in promoting the application of aqueous zinc batteries, particularly under harsh conditions.
An ultrathin Janus separator composed of Ag nanowires and bacterial cellulose is designed for dendrite‐free zinc‐metal batteries. This Janus separator with abundant zincophilic sites, uniform‐distributed electric/thermal field, and enhanced ion transport kinetics can help to realize the stable cycle life over 1000 h under 80 mA cm−2 and sustain over 600 h at 10 mA cm−2 under 50 °C.
•A coupling semi-theoretic analysis model of the multilayer direct laser deposition process is established.•Final stable process can be achieved by ensuring the initial working plane is placed within ...the range of Sset,large.•Residual temperature effectively improves the initial WP placement range and slow down the instability proceeding.•Optimized deposition head lift height range for the DLD process with different temperature steps is shown.
Based on the layer by layer cladding characteristics of the direct laser deposition (DLD), the optimal selection strategy of deposition head lift height is one of the effective methods to maintain the manufacturing process stability, improve product quality, and reduce complex post-process. However, owing to the temperature step caused by changeable layer residual temperature, the selection of deposition head lift height becomes extremely complex. In this paper, to clearly analyze the effect of temperature step on selection strategy of deposition head lift height for the DLD multilayer deposition process with a 1.85 kW fiber laser and a coupled coaxial four-channel nozzle, a semi-theoretical model considering the main physical phenomena involved in DLD process is proposed, validated, and applied. Here, working plane position, deposition head lift height, and step of residual and preheating temperature are considered as input process variables while manufacturing stability and error are determined as process responses. Results show that without considering the temperature influence, the final manufacturing stability can be achieved by ensuring that the distance between the deposition head and the initial working plane is less than the maximum relative distance corresponding to the selected deposition head lift height. When the layer residual temperature is considered, the single-layer cladding height steps positively, which makes the extreme working plane position positively migrated, and the manufacturing stability is also further enhanced. However, due to the migration of the finally stable working plane position, the manufacturing errors are also conditionally changed. Finally, in order to obtain an optimal manufacturing process, for any DLD process where the initial working plane position has been determined, the deposition head lift height should be selected slightly smaller than the single-layer height corresponding to that determined plane under residual temperature condition (hTr,Si), otherwise the manufacturing process will gradually lose stability and lead to fabrication failure.
Highlight removal is a critical and challenging problem. In view of the complex highlight phenomenon on the surface of smooth liquor bottles in natural scenes, the traditional highlight removal ...algorithms cannot semantically disambiguate between all-white or near-white materials and highlights, and the recent highlight removal algorithms based on deep learning lack flexibility in network architecture, have network training difficulties and have insufficient object applicability. As a result, they cannot accurately locate and remove highlights in the face of some small sample highlight datasets with strong pertinence, which reduces the performance of some tasks. Therefore, this paper proposes a fast highlight removal method combining Usup.2-Net and LaMa. The method consists of two stages. In the first stage, the Usup.2-Net network is used to detect the specular reflection component in the liquor bottle input image and generate the mask map for the highlight area in batches. In the second stage, the liquor bottle input image and the mask map generated by the Usup.2-Net are input to the LaMa network, and the surface highlights of the smooth liquor bottle are removed by relying on the powerful image inpainting performance of LaMa. Experiments on our self-made liquor bottle surface highlight dataset showed that this method outperformed other advanced methods in highlight detection and removal.
PDF
