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Abstract: With the development of electric vehicles, higher energy and battery efficiency have become the main concerns of electric vehicle manufacturers and consumers. The main component of vehicle charger is DC/DC converter. In the DC/DC converter with power switch, because of the phase shift of the full bridge, the switch has to work at zero voltage or zero current, which leads to some current problems. If the voltage on both sides of the transformer changes, it means that there will be some defects in its performance. The power factor correction converter, which is commonly used in modern electric car charger, has the advantages of high performance and sufficiency in the whole charging process. Therefore, this paper designs an improved Rogowski converter to improve the charging efficiency of electric vehicles. Roche converter is usually used as a converter from DC to DC, which has better voltage regulation ability under rapidly changing line voltage. At the same time, in this work, a reformed independent electric vehicle charger based on Roche converter is developed. In order to suppress voltage oscillation, two devices, namely a switch and two clipping diodes, are connected to the primary side of the high-frequency transformer. Roche converter handles the operation of discontinuous conduction mode, which reduces the complexity of control and keeps the output of converter constant. In the feedback system, constant current and constant voltage mode technology are combined with PI controller to improve the capability and reduce transmission leakage. Finally, the performance of the proposed system is evaluated by MATLAB, and the results are satisfactory.Abstract: With the development of electric vehicles, higher energy and battery efficiency have become the main concerns of electric vehicle manufacturers and consumers. The main component of vehicle charger is DC/DC converter. In the DC/DC converter with power switch, because of the phase shift of the full bridge, the switch has to work at zero voltage or ze...Learn More
Abstract: In the ultrasonic positioning system, the positioning system has a certain delay due to the sequential ranging at the ultrasonic receiver, the system's decoding time and the signal transmission time, which has a great impact on the positioning accuracy. The solution is to set a time compensation factor for the speed of the object to be positioned and the positioning time of the system unit to compensate for the error, so as to achieve the same positioning accuracy when the object to be positioned is stationary; then the Kalman filter algorithm is used to correct the positioning results at different speeds, so that the positioning accuracy of the ultrasonic positioning system can be further improved. The simulation results show that the positioning accuracy can be stabilized within 2cm at a certain speed, which is able to move and position the object to be positioned at a certain speed; finally, the experiments are conducted using the Arduino Uno as the core positioning system, and the experimental results verify the simulation results and show that the solution can The experimental results verify the simulation results and show that the solution is able to improve the positioning accuracy of moving objects, especially when the object to be positioned moves at a constant speed, the positioning accuracy tends to be stable, and the object to be positioned with a certain speed can be positioned well.Abstract: In the ultrasonic positioning system, the positioning system has a certain delay due to the sequential ranging at the ultrasonic receiver, the system's decoding time and the signal transmission time, which has a great impact on the positioning accuracy. The solution is to set a time compensation factor for the speed of the object to be positioned a...Learn More
Abstract: There are many lakes in China and they are widely distributed, so it is important to have comprehensive information on lakes to promote the implementation of major water network projects, ecological and environmental restoration of rivers and lakes, and smart water conservancy construction. This paper uses a deep learning model to identify and extract lake entities, and provides a reference for mining effective lake information from lake text. Firstly, the Named Entity Recognition (NER) method and annotation specification are customized, and a corpus of lake texts is established. Secondly, considering the small size of the self-built corpus and the sparsity of text information may affect the performance of the model and the recognition effect, a lightweight pre-training model (ALBERT) is introduced to generate high-quality word vectors as a two-way gating cycle The unit-conditional random field (BiGRU-CRF) model is used to generate the input layer feature vectors, and the attention mechanism is incorporated into the model to add feature weights to the semantic information of the entities to improve the entity feature extraction effect. Finally, a large number of validation experiments are completed, and the recognition effects of the four deep learning models are compared. The results show that the ALBERT-BiGRU-Attention-CRF model has good recognition effect on the dataset as a whole, with accuracy, recall and F1 reaching 91.26%, 90.38% and 90.81%, respectively. In addition, the model outperforms the other comparison models for the recognition of all four types of entities that occur at high frequencies.Abstract: There are many lakes in China and they are widely distributed, so it is important to have comprehensive information on lakes to promote the implementation of major water network projects, ecological and environmental restoration of rivers and lakes, and smart water conservancy construction. This paper uses a deep learning model to identify and extr...Learn More
Abstract: The staggered story isolated structure is a new type of isolated structure developed from the base isolated structure. It has great isolation performance under ordinary earthquakes. However, the problem of long-period earthquakes exists in many areas. The prolongation of the natural vibration period of the structure and the resonance caused by the low-frequency part of the long-period earthquakes should not be ignored. The research on the response of the staggered story isolated structure under the long-period earthquake is not perfect. Two finite element models of staggered story isolated structure were established and non-linear time-history response analysis were carried out under ordinary earthquakes and long-period earthquakes, which including near-fault pulse-type long-period earthquakes and far-field harmonic-like long-period earthquakes. Results show that the natural vibration period of the staggered story isolated structure is prolonged, the seismic response is reduced. Under long-period earthquakes, the story drift angle, bearing displacement, story shear, plastic hinges and stress damage of staggered story isolated structure are partly larger than those of ordinary earthquakes. Under the far-field harmonic-like earthquakes, isolation performance is significantly different from those under the near-fault pulse-type earthquakes. And there are significant differences between the two models. The structure has the characteristics of vertically irregular structures and the weak position of the structure is located near the isolation layer, so more attention should be paid to the project.Abstract: The staggered story isolated structure is a new type of isolated structure developed from the base isolated structure. It has great isolation performance under ordinary earthquakes. However, the problem of long-period earthquakes exists in many areas. The prolongation of the natural vibration period of the structure and the resonance caused by the ...Learn More
Abstract: Magnetic skyrmions offer the potential as an information carrier for the next-generation storage and computing devices such as racetrack memory devices, logic gates, and even neurocomputing owing to the topology-protected structure, nano-scale size and relatively low driving current compared to traditional devices. The discovery of magnetic skyrmions at room temperature also lays the foundation for realizing room-temperature magnetic skyrmion spintronic devices. Defects and impurities are unavoidable in real materials. These pinning centers significantly affect the dynamics of the skyrmion, including the critical driving current, and the Hall angle, etc. The study on room-temperature magnetic skyrmions in thin films has shown that the effect of pinning can be dominant at room temperature. Hence, the study of pinning effects and the skyrmion-pinning interaction is significant to the motion of magnetic skyrmions at room temperature and the realization of room-temperature magnetic skyrmion spin devices Magnetic skyrmion motion can be strongly modified under the effect of pinning (defects and purities). Moreover, these effects can inspire us to utilize artificial pinning centers to manipulate the dynamics of skyrmions. In this article, we introduce the models for skyrmion motion and pinning effect at room temperature and gives an overview of the methods for creating different types of pinning and their impact on the skyrmions. When pinning is induced by replacing or adding atoms, setting vacancies, changing the material thickness or curvature, or changing magnetic parameters, the skyrmions hall angle will vary. Moreover, the magnetic skyrmions can be fixed in a particular region, move along a specific orbit and overcome thermal perturbations at room temperature under the effect of pinning, which helps to realize magnetic skyrmion spin devices at room temperature.Abstract: Magnetic skyrmions offer the potential as an information carrier for the next-generation storage and computing devices such as racetrack memory devices, logic gates, and even neurocomputing owing to the topology-protected structure, nano-scale size and relatively low driving current compared to traditional devices. The discovery of magnetic skyrmio...Learn More
Abstract: In recent years, the transportation capacity of Shuohuang Railway, an important coal transportation corridor in China, has become saturated. To exploit potentialities and raise efficiency, transportation organization optimization is the key way in the short term. Based on elaborating the present situation of traffic volume on the Shuozhou-Huanghua railway, the traffic volume of 2030 is predicted by the time series method, which is found that under the condition of existing equipment and transportation organization, the railroad capacity is not able to meet the transportation demand. This paper analyzes the technical conditions under the traffic volume target of 450 million tons and proposes the phased optimization steps of transportation organization on the Shuozhou-Huanghua railway from two aspects of station operation efficiency and train transportation organization based on a new type of automatic parking device. A series of optimization measures for capacity expansion and efficiency improvement are raised, such as dwell time compression of cargo at the station, skylight influence area compression and interval parking mode on skylight day. It is found that when the proportion of 20,000 tons of trains reaches more than 60%, the Shuozhou-Huanghua railway can achieve the volume target of 450 million tons. The compression of the skylight influence area could add 197 additional trains of 20,000 tons every year. And the interval parking mode could increase the annual capacity by about 690,000 tons.Abstract: In recent years, the transportation capacity of Shuohuang Railway, an important coal transportation corridor in China, has become saturated. To exploit potentialities and raise efficiency, transportation organization optimization is the key way in the short term. Based on elaborating the present situation of traffic volume on the Shuozhou-Huanghua ...Learn More
