bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and analysis of field test of surface unmanned boat radio
Authors: Han Qifei , Zhao Honghua , Lin Yifei , Gong Xuyin , Zhao Jian , Hu Zhitong
Published: February 2021

Communication distance and real-time monitoring are important performances of surface USV radio stations, which can better play the role of smooth communication information between surface USV and shore-based platform and real-time monitoring of USV dynamics, usually in the field. Test verification. This article analyzes the main problems in the field communication distance and real-time monitoring test of the surface unmanned boat radio station, introduces the evaluation method of the field wireless electromagnetic environment monitoring, designs the network environment of the shore-based computer and the surface unmanned boat industrial control computer, and designs the surface Field test plan for man- ship radio station. The test analysis shows that the design scheme is feasible and the communication between the surface unmanned boat and the shore-based platform is smooth, which can better monitor the dynamics of the surface unmanned boat, thereby improving the operation quality of the surface unmanned boat.
A distributed high-density resistivity meter working on a two-wire cable
Authors: Dong Xiquan , Luo Wang , Wang Hongpeng , Ge Jian , Liu Huan , Dong Haobin
Published: February 2021

High-density resistivity meter is a common instrument used in shallow geophysical exploration. At present, the structure of the centralized high-density resistivity meter is bulky, while the distributed instrument needs more than 7 core cables, and the long measuring line needs to relay power supply to the intelligent electrode to provide enough voltage, so it is not convenient to use in the field. Aiming at the above problems, a new type of distributed high-density meter is developed, which can realize the power supply, communication, and measurement functions of distributed high-density meter and carry out multi-channel measurement through the time-division multiplexing of a two-wire cable and the short-time power supply of supercapacitor. Finally, the performance of the instrument was verified by experiments.
Equilibrium Model of Electricity Market Bidding Considering Incentive-based Demand Response
Authors: Zheng Yaxian , Chen Zhongyao , Shi Xinhong , Wang Gaoqin , Lin Kaiying , Wang Beibei
Published: February 2021

In the initial stage of electricity market construction, incentive-based demand response can effectively mitigate price spikes. Considering the overall equilibria of the market, it is of great significance to study the impact of incentive-based demand response on market clearing and participants’ behaviours. Firstly, this paper analyzes the compensation methods of incentive- based demand response and establishes an equilibrium model of day-ahead electricity market bidding that takes into account demand response. Secondly, considering the overall equilibrium conditions of the market, the overall equilibrium model of the market is established. Results show that the incentive-based demand response mechanism has a restraining effect on the generators’ bidding, and the load reduction effect is prominent when the network is congested.
Optimal utilization of load side power and heat resources based on aggregator mode
Authors: Zhu Weijiang , Cheng Xiao , Sun Lishi , Cong Lin , Wang Bing , Tian Zheng , Wang Nan
Published: February 2021

Combined cooling, heating and power system (CCHP) can realize the cascade utilization of energy and improve the energy utilization efficiency. Focusing on the phenomenon that the traditional self-sufficiency mode is easy to cause insufficient or excess regional energy supply, considreing the complementarity between different regional load characteristics, an internal multi-region interconnected complementary energy supply method based on aggregator mode was proposed. In order to solve the problem of uncertainty in the optimal dispatching of multiple resources in the region under the aggregator mode, an optimal dispatching model based on interval linear programming was constructed, which took the minimum operation cost of aggregator as the objective function. The feasibility and effectiveness of the method are verified by analyzing the aggregator mode in residential area, commercial area, office area and industrial area. The results show that the operation cost can be reduced and the economic benefit can be improved under the aggregator mode.
Optimization Study of Poles-slots Combination of Large Capacity Offshore HTS Wind Generator Based on Ansys Maxwell
Authors: Wang Qiong , Li Yan , Deng Guangyu , Zhang Huiyuan , Li Yueqiao , Xu Jun , Wang Xin
Published: February 2021

The superconducting wind turbine has the advantages of large capacity, high power density, small size, low weight, high efficiency and low cost. In the case that the rotor has many poles, how to choose the number of slots of stator is very important to the performance of the motor. This paper took 10 MW Offshore HTS Wind Generator as an example, analyzed the influence of different poles-slots combination on the performance of the generator, and finally determined a set of relatively reasonable scheme. The simulation results showed that this scheme can effectively reduce the high harmonic of no-load counter electromotive force and improve the induced voltage distortion rate and torque vibration, significantly improve the motor performance. It is of guiding significance for the structural optimization of superconducting motors.
Study on the influence of heat pump and heat storage device on the accommodation of wind power curtailment in the integrated energy system
Authors: Liu Meijie , Li Zhongwei , Wu Quanbao
Published: February 2021

In order to solve the wind curtailment problem in an integrated energy system (IES), this paper starts from the structure of the IES and analyzes the related contents of heat pump, heat storage device and cogeneration units in the IES. At the beginning of this article, the principle, performance coefficient model and energy efficiency curve of the heat pump are first studied. Correspondingly, the principle of heat storage device and the model of heat storage and release strategy are studied. Then the principle and operating characteristic model of cogeneration units are studied. Based on the principle of each part, combined with the operating constraint conditions of the IES, the IES including heat pump, cogeneration units and heat storage device is constructed. An example is used to simulate the operation in the Energy Plan software, different scenarios were established in the simulation process for analysis to study the influence of heat pumps on the accommodation of curtailed wind power in the IES. The simulation results show that the heat pump can promote the accommodation of wind power, reduce the curtailment rate and the cost of power generation to a certain extent in the IES. From the results of simulation analysis, it can also be concluded that the IES including both heat pump and heat storage device has better wind power accommodation capacity.
Optimization Strategy of Electric Heating with Load Regulation Ability
Authors: Wang Qing , Liu Xu , Liu Song , Lin Zhongyu , Chen Yang , Li Congcong
Published: February 2021

In recent years, more and more users choose electric heating to replace traditional centralized heating mode in the northern area. The flexibility of electric heating, the energy consumption characteristics of buildings, the regulation ability of users and Time-of-Use (TOU) electricity tariff give much possibility to optimize the output power strategy of electric heaters. The existing electric heating control system, where the suitable working temperature is usually used as the only set value for human life and working environment, leads to unnecessary energy consumption in some low heat demand area.

This paper, focused on a commercial used building in Shandong province, takes different heating demand characteristics into consideration, establishes electric heating load model and analyses each load’s regulation ability. Six distributed electric heaters are installed in the building, with one room equipped with one electric heater. The heater is modelled based on the parameters and output power characteristics. For the building itself, the energy consumption characteristics and thermal inertia are also analysed and presented.
A Control System of Cell Electroporation induced by Double Nanosecond Pulsed Electric Field
Authors: Peng Hao , Zhang Lin , Liu Xin , Guo Fei
Published: February 2021

A feedback linearization control system, which is used to study and analyze cell electroporation induced by double nanosecond pulsed electric field, is proposed in this paper. Then the effects of the control system which controls the process of electroporation induced by unipolar or bipolar double pulse are investigated to achieve controllability of electroporation. The simulation results show that the output of the control system, namely, the transmembrane potential can reach a stable value of 0.78 (-0.78)V, the radius increases linearly from 0.86nm to 0.88nm and the pore density increases linearly to 2.072×108m−2 (2.077×108m−2) when the input of the control system, the expected transmembrane potential is set to 0.79 (-0.79) V, and these results are in well agreement with the simulation result obtained by computing the related equations of electroporation, demonstrating that the control system developed in study can well regulate cell electroporation under the action of double nanosecond pulsed electric field. Overall, the control system can help the researcher to obtain the corresponding output electroporation parameters by directly inputting the expected transmembrane potential.
Optimal Computation of Small Hydropower Cluster Generation Based on River Topology
Authors: Chen Lili , Zhang Meiyan , Shen Xudong , Li Haitao , Peng Xuehu
Published: February 2021

Small scale hydro-power (SHP) is clean, renewable, low-carbon and it is much more environmental protection than lager scale hydro-power. In remote mountainous regions with abundant water resources, adjacent small hydropower plants (SHPP) are usually clustered to send out the electrical power. However, the power output of a SHPP varies with the changes of water flow which brings challenges for both the reliability of power systems and power grid planning. Moreover, the generation state of SHPP upstream will also cause the change of water flow downstream, which make the problem more complex. This paper proposes a method to reach the optimal generation of SHP cluster, considering the mutual influence of SHPP in the river system. The co-relation of water flow between different SHPPs is quantified based on river topology analysis. The classical genetic algorithm (GA) is used to compute the problem. A realistic system in Southeast China is studied to illustrate the feasibility of the proposed method.
Low-power LDO Design of High-efficiency Class AB OTA Based on Adaptive Biasing
Authors: Yang Hao , Huang Shengming , Duan Quanzhen
Published: February 2021

This design proposes a new low-dropout linear regulator (LDO) with low input voltage and low standby power consumption. A new type of adaptive bias circuit is proposed, which uses a high-efficiency class AB OTA based on class AB differential input stage and local common mode feedback (LCMFB), which not only increases the gain bandwidth product (GBW), but also improves current efficiency, in addition, a dynamic charging transistor (DCT) is used to enhance the transient characteristics of the circuit. The circuit design uses 0.18μm standard CMOS technology to achieve a stable output of 1.0V after the power supply voltage is adjusted from 1.2V, and the maximum output current is 100mA. The quiescent current is only 2.3μA at no-load, when the load current is converted from 1mA to 100mA within 1μs, the overcharge voltage is less than 130mV, and the full range of load current stability from 1mA to 100mA is achieved under the maximum 100pF load capacitor.
Reliability Modeling and Analysis of Reactor Protect System Based on Petri Net
Authors: Zhang Dongliang , Zhang Kaiwen , Wang Liufeng , Hong Qinqin
Published: February 2021

Digital control is an inevitable trend in the development of nuclear power. The application of digital control systems in nuclear power plants not only improves the control capability of nuclear power plants, but also increases the complexity of the system. Traditional reliability analysis methods (such as event trees and fault trees) can only perform static analysis on the reactor protection system, but cannot reflect the impact of maintenance activities on system reliability. In the dynamic analysis method, the Markov model is usually applied to the exponential distribution, and the failure and maintenance process of the reactor protection system does not all obey the exponential distribution. In this paper, the Petri net method is used to model the reactor protection system, and the modules are modeled separately according to the function of the system, and finally the model is integrated. Modularization improves the flexibility and understandability of the model, shortens modeling time, and improves robustness. The proposed model was simulated using the GPenSIM tool, and the state reachability diagram of the system with or without maintenance process was obtained, and the probability of shutdown and refusal was obtained.
SoC-Based Dynamic Droop Control for Battery Energy Storage Systems in DC Microgrids Feeding CPLs
Authors: Wang Jianmin
Published: February 2021

In this paper, a dynamic state-of-charge (SoC)-based droop control and bus voltage stabilization strategy has been proposed for battery energy storage systems (BESSs) feeding constant power loads (CPLs). Firstly, a SoC-based dynamic droop control is proposed to realize proportional distribution of power. Secondly, a dynamic average consensus (DAC) algorithm is adopted to ensure that all SoC converge to the same value simultaneously. Thirdly, a nonlinear disturbance observer (NDO) and a backstepping controller are integrated to stabilize the DC bus voltage. In this way, the rapid voltage recovery and power distribution are obtained when droop coefficient is time-varying. Simulation results verify the feasibility and effectiveness of the proposed control strategy.
A Two-Stage Detection Method of Rigid Pantograph Catenary Contact Points Using DCNNS
Authors: Zheng Danyang , Lu Xuemin , Quan Wei , Peng Yuchen , Liu Yueping , Chen Jim X.
Published: February 2021

Pantograph catenary contact point is an important monitoring object during pantograph catenary operation, which reflects the state of pantograph catenary operation. However, due to the relatively small contact area of the target area, it is still a challenge to locate the contact point quickly and accurately. Therefore, we propose a two-stage detection method of rigid pantograph catenary contact points based on deep convolution neural network. Firstly, yolov3 network is used to locate the pantograph catenary contact part, which can obtain the target area including contact points. Then, four key points generated by the intersection of rigid pantograph and catenary can be obtained by using the key point detection network in the target area. Finally, the positioning of pantograph catenary contact points is obtained by geometric calculation. The experimental results on the railway operation data set collected by the traction Laboratory of Southwest Jiaotong University show the effectiveness of the method.
Research on Fixed Separated Low Voltage Switchgear Based on Electronic Sensing Technology
Authors: Shen Qianwei
Published: February 2021

In order to solve the problem of poor accuracy of traditional partial discharge identification methods for switchgear, this study introduces the control principle of single chip microcomputer and designs a new partial discharge identification method for switchgear. Firstly, the partial discharge characteristic data of the switch cabinet are collected to detect the operation state of the switch cabinet and the abnormal values therein. Then, according to the acquisition results, the characteristic types of partial discharge in the switch cabinet are judged, thus realizing the identification of partial discharge in the switch cabinet. The simulation results show that the recognition method has high recognition accuracy and the recognition process takes less time, which proves that the method is practical and reliable.
Multi-keyword Cipher-text Retrieval Method for Smart Grid Edge Computing*
Authors: Zhu Jing , Wu Tao , Li Jintao , Liu Yanbin , Jiang Qixin
Published: February 2021

With the continuous deepening of China's power grid intelligent upgrading and the rise of edge computing technology, power grid terminals can carry out data storage and intelligent calculation at the edge of the power grid. However, the generated data by users may cause the leakage of user privacy information. The power grid edge system can retrieve the user's electricity data on demand, so as to improve the level of privacy protection and reduce the demand of transmission and computing resources through the localized storage of data. Therefore, how to carry out privacy protection and on-demand retrieval is a key problem to realize the intelligent power grid edge. In this paper, a multi-keyword cipher-text retrieval scheme (MCR- SGEC) for smart grid edge computing is proposed, which can achieve accurate matching of index and trap door, and has low spatial complexity. At the same time, on this basis, a multi-keyword fuzzy cipher-text retrieval method for smart grid edge computing (MFSE-SGEC) is proposed, which allows users to have spelling errors, which makes the user experience better.
Measurement and Analysis of 220kV Overhead Transmission Line Parameters
Authors: Xu Minhu , Guo Yun , Shen Yubo , Zhang Kexin , Zhang Dewen , Han Siwei , Lan Sen , Liu Heqian , Zhang Hang , Xu Chao
Published: February 2021

This paper introduces the items and principles of transmission line parameter test, finds out the interference factors through the detailed analysis of the field test results, and puts forward the relevant precautions.
A Low-Cost Solution for Leader-Follower Formation Control of Multi-UAV System Based on Pixhawk
Authors: Liu Xuancen , Liu Longbin , Bai Xibin , Yang Yueneng , Wu Hangjin , Zhang Shifeng
Published: February 2021

In recent years, cooperative multi-UAV systems have shown great performance in a variety of potential applications. Aiming at the problem of fixed-wing UAVs cooperative formation flight, this paper presents a low-cost system based on Pixhawk autopilot for keeping the shape of the formation. The kinematic relationship of a leader-follower UAV formation is established and a fuzzy PID control law is designed for the follower to maintain the expected position relative to the leader. Wireless data transmission between the leader and followers is achieved by using several radio telemetry modules. The proposed formation control system is validated by a series of successful flight experiments using 3 small-scaled UAV models, which has proven its feasibility and reliability.
Circuit Controller for PF Converter System Based on CODAC Core System
Authors: He Shiying , Huang Liansheng , Chen Xiaojiao , Wang Guanghong , Wang Zejing , Zhang Xiuqing , Zuo Ying
Published: February 2021

The poloidal field converter system of the International Thermonuclear Experimental reactor, which is developed, assembled, and tested by the Institute of Plasma Physics of the Chinese Academy of Sciences, uses the CODAC core system provided by ITER organization to design its control system. This paper completes the design of the circuit control system as well as realizes the transmission, state transition, and real-time control of the operating status of the poloidal field converter system to meet specific requirements for the control cycle of the control system. This paper provides solutions to some key problems, such as the state transition, real-time transmission, and operating state display, and real-time control of the converter circuit control system. The system designed by this paper has been successfully tested in the ITER PF prototype and ITER PF test platform.
Research on Multi-mode Operation Control Strategy of Feeder Flexible Interconnection in Distribution Network Based on Flexible Multi-State Switch
Authors: Zhou Xueting , Yang Wanli , Luo Yulan
Published: February 2021

Aiming at the problems of multi-mode operation and switching, unbalanced feeder load and heavy load of main transformer in flexible interconnection system of distribution network based on Flexible Multi-State Switch(FMSS), a multi-mode operation control strategy of feeder interconnection in distribution network based on Virtual Synchronous Generator (VSG) is proposed,which includes load balancing control strategy and heavy load main transformer automatic control strategy. Firstly, according to the feeder and main transformer load status, the operation mode of system is divided.Then, through the analysis power transmission and switching logic of different operating mode, active power control instructions of FMSS under multi-mode operation are obtained. So that multi-mode stable operation and free switching of the system, the feeder load balancing and main transformer heavy load automatic regulation are realized. In addition, there is no need for control strategy switching. Simulation verifies the rationality and effectiveness of the proposed control strategy.
Coordinated Control Strategy Research of Multi-terminal Cascaded Hybrid HVDC System
Authors: Lin Chang , Zhou Jiapei , Zeng Rui , Li Baohong , Jiang Qin
Published: February 2021

The multi-terminal cascaded hybrid HVDC system is proposed in recent years and it will be put into reality in near future. This paper investigates its control characteristics when MMCs are in master-slave strategy, and the coordinated control improving system stability is also proposed. It is found that the MMC inverter in constant DC voltage control would become a rectifier when fault happens. To solve such problem, the active power reference is immediately adjusted once the fault occurs, such that the DC side operation and AC side voltage stability can both be improved. Nevertheless, the proposed control strategy can also alleviate the large fluctuations in fault recovery process, so that the system can steadily return to original operation point. The simulation results in PSCAD/EMTDC verify the effectiveness of the proposed coordinated control strategy.
Research on Intelligent Recognition and Control Device of Aviation Line Number
Authors: Zhao Changfu , Cao Guohua , Ding Hongchang , Zhang Ying , Hou Han
Published: February 2021

In order to solve the problems such as low sorting efficiency, high error rate and inability to match the corresponding installation position on aviation wiring, we propose a machine vision line number recognition method, which is based on the threshold segmentation algorithm of gradation histogram to identify the line number and index the recognized results. The wire harness recognition system mainly includes three parts: wire number positioning, wire number character segmentation and character recognition. Experimental results show that the online detection speed of the vision system is 30m/min, the accuracy rate is higher than 98% and the average time is 0.04s. By matching the recognition results, index to the position where the wiring harness is to be installed to meet the requirements of aviation wiring.
Research on Single Event Effects of Ethernet MAC Controller on Manned Spacecraft
Authors: Bo Zhu , Jialiang Li , Hongxiang Chen , Shijia Wang , Xin’an Qiu , Mingyu Cheng , Jiagao Xia , Jiaqi Gao
Published: February 2021

In order to realize higher speed and large flow network communication on the new manned spacecraft independently developed in China, it is necessary to apply Ethernet technology. Considering the cost and application prospect, it is planned to use industrial Ethernet control chip. So it is necessary to verify whether it can meet the special requirements of the space environment. According to the space environment of the manned spacecraft design orbit, and the sensitive characteristics of the Ethernet controller chip itself, it is necessary to focus on verifying its single-particle effect. This paper introduces in detail the single-event effect of the Ethernet controller in China for the first time. The Bi-ion and Kr ions of the HIRFL cyclotron are used to carry out the single-event effect on the KSZ8851-16MLLJ Ethernet MAC controller produced by MICREL. The evaluation test, including the single-particle test design, hardware platform, software functions and test data, finally gave the test conclusion.
Backstepping sliding mode control of electric linear load simulator
Authors: Zhang Jianwei , Fan Yuanxun , Cao Dawei , Lu Pengcheng , Zhang Jiacheng
Published: February 2021

In order to solve the excess force problem in the electric linear load simulator (ELLS), a backstepping sliding mode controller based on the backstepping control idea is proposed. According to the function, the state of the system is divided into load torque subsystem and PMSM mechanical subsystem. First, the virtual control of the load torque subsystem is designed, and then the controller is designed for the PMSM mechanical subsystem, and the Lyapunov stability is proved. Finally, the simulation test is compared. The simulation results show that, compared with the traditional PID control, the controller based on the backstepping sliding mode design can effectively suppress the excess force and improve the loading accuracy of the system.
Design of UAV yaw Angle controller based on variable domain fuzzy PID
Authors: Ning Wang , Zhe Li , Xiaolong Liang , Jiaqiang Zhang
Published: February 2021

Four-rotor UAV is widely used in reconnaissance missions, UAV usually needs to adjust the yaw angle before reconnaissance aerial photography. To improve the speed of the four-rotor uav at the adjustment of yaw angle, this paper presents a variable-domain fuzzy PID controller. First, we established the nonlinear dynamic model of four-rotor UAV. Then, we fuzzed the corresponding variables in the governing equation, formulated fuzzy rules and introduced variable theory to adjust domain of discourse. Finally, we used simulink software to carry out experiments. The experiment result shows that variable-domain fuzzy PID controller has some undoubtedly advantages in performance evaluation compared to traditional PID controller, which including dynamic property and steady state error, and can be used to improve the quality of the adjustment of yaw angle.
Fluid-solid-thermal coupling analysis of an underwater valve
Authors: Han Jiazhen , Xie Yudong , Wang Yong , Pan Zihan
Published: February 2021

An underwater valve at 3000 meters underwater was chosen as the research object, aiming at obtaining the force characteristics of the underwater valve under high pressure and large temperature difference in the deep sea. The principle of fluid-solid-thermal three-field coupling was analyzed by using Fluent and ANSYS Workbench. Through numerical simulation, the fluid temperature distribution, the stress and deformation of the valve were obtained, and the valve was loaded. The influence of pressure and temperature on the performance of underwater valve was discussed. The results show that the fluid medium inside and outside the valve exchanged heat due to the large temperature difference, and vortexes were generated at the bottom of the valve seat, and the fluid pressure energy was converted into heat energy. The force of thermal stress generated by heat exchange on the valve body was greater than the equivalent stress generated by thermal-mechanical load.
Research on Electrical Control and Programmable Controller Based on Laser Tracking Measurement
Authors: Xing GuanSheng , Meng WeiChuan
Published: February 2021

Different production technology and process have different requirements for control circuit. However, no matter what kind of control circuit, it is composed of some basic control links. Programmable controller is a common electronic data control program, which not only plays a lot of advantages in industrial control system, but also is more and more widely used in people's daily life. It is an essential basic equipment in industrial automation system at present. As a kind of high-precision three-coordinate measuring equipment, laser dynamic tracker can be used to measure the spatial position of various single parts and complete sets of equipment. This paper mainly introduces the application of laser tracking system in electrical control and programmable controller, and looks forward to the development prospect of laser tracking detection technology.
Transient simulation model and process simulation analysis of fast cut back process in thermal power plant
Authors: Ruling Huang , Lin Li , Qing Cao , Yan Gao , Tao Luan
Published: February 2021

Fast Cut Back (FCB) technology of large thermal power plant can maintain the isolated operation of auxiliary power after the units are disconnected from the power grid. FCB unit can immediately cut off all external loads without turbine or boiler shutdown in case of large power grid failure, and supply power immediately as the external power grid fault eliminated, which has a very important impact on improving the stability and the recovery speed of the power grid system. Therefore, it is necessary to establish a dynamic mathematical model of thermal power plant to simulate FCB process. According to the principle of mass and energy balance, a dynamic mathematical model of 1050 MW thermal power unit was established. The model considered the change trends of main steam pressure and temperature caused by the action of main steam valve and high-pressure (HP) bypass valve in FCB process, and the action characteristics of safety valve and pressure control valve (PCV) valve in FCB system. This model provides a reference for the simulation and control of FCB process in thermal power unit.
Kinematics analysis of pneumatic soft manipulator
Authors: Shan Lijun , Li Yunfei
Published: February 2021

A software mechanical grabbing device is designed to deal with space debris. The robotic arm is composed of unit segments of modular design, and the kinematic model of the unit segments of the mechanical arm is established by simplifying it into a cantilever beam model. The relationship among the driving space, joint space, and operation space of the unit section is analyzed, and its kinematics equations are established.
A survey of recommendation systems based on deep learning
Authors: Liu Baichuan , Zeng Qingtao , Lu Likun , Li Yeli , You Fucheng
Published: February 2021

Faced with massive amounts of data, people may not be able to choose the items they like. The recommendation system came into being, and it has achieved a breakthrough for a long time. Using deep learning can mine the hidden attributes of users' items and integrate them well, bringing new changes to the recommendation system. This article describes the deep learning-based recommendation system and the traditional recommendation system, and analyzes their advantages and disadvantages.
Fault Stage Feature Extraction Method Based on Antinoise Gradient Operator Morphological Filters
Authors: Haibing Zhang , Dongshan Ruan
Published: February 2021

The cyclical impact signal aroused by mechanical fault contains feature information, such as fault type and fault stage. However, a transient impact component is usually modulated on the fundamental frequency and mixed with a large amount of noise. Thus, it is difficult to be extracted effectively. A feature extraction method of faults stage is presented based on morphological filter theory. An antinoise morphological gradient operator is applied to signal filtering. This operator can weaken the noise and clearly highlight the impact characteristics of different fault stages. The kurtosis of the spectrum band, including the passing frequencies of mechanical components, is used to differentiate fault stages. The applications on simulation signals and bearing test data indicate that this method can realize accurate extraction of fault characteristic frequency submerged in noise and effective distinction of different fault stages.
PMSG Wind turbine grid-connected pre-synchronization technology based on virtual impedance
Authors: Meng Zi Shu , Lu Yong Geng
Published: February 2021

With the integration of large-scale wind power, the inertia of the whole grid system is reduced. Therefore, virtual synchronous machine (VSG) technology has become a new strategy for wind power integration. In view of the fact that the VSG grid connected control of permanent magnet direct drive wind turbine does not consider the constraints of grid connection conditions, a scheme combining VSG technology with pre synchronization technology is proposed in this paper. VSG technology is still used in the PWM control of grid connected inverter. However, considering that there is no deviation between the phase angle of output voltage and the phase angle of grid voltage, it is impossible to judge whether the grid connection conditions are met or not when there is no deviation between the phase angle of output voltage and that of grid voltage.
Design of the self-oscillating loop of the optically pumped cesium magnetometer
Authors: Xue Liyue , Dong Haobin , Luo Wang , Ge Jian , Liu Huan
Published: February 2021

The self-oscillating loop is an important part of the optically pumped cesium magnetometer, and its working characteristics directly determine the accurate measurement of external magnetic field. The design of the self-oscillating loop has been discussed in this paper, including a signal conditioning circuit, a phase shifter and a frequency meter. It can be used to precisely improve the accuracy of resonance signal in a wide range of frequencies from 50 kHz to 350 kHz. The relative error of our system is less than 0.5×10−6 and it has a good prospect in the optically pumped cesium magnetometer.
Research on 3D digital design of AC filter field application in Qingnan ± 800kV converter station
Authors: Ran Ruijiang
Published: February 2021

Qingnan ± 800kV converter station AC filter bank adopts the improved "Tian" type layout scheme. Through the summary in different majors’ modeling, equipment layout, two-dimensional drawing and material statistics methods, the design efficiency and quality can be effectively improved. However, at present, the data transmission between 3D design software and some professional calculation software is not smooth, and a large number of models run slowly after the final assembly. Some software functions are more cumbersome and other issues are still restricting the development of 3D design. This needs to constantly optimize the software function and design process, promote the development of 3D digital design mature.
Mechanical Design and Electrical Experiment of Large Current Connector for Transformer Terminal and Drain Wire in Distribution Network
Authors: Wei Song , Hong Xiang , Qing Zhou , Fangxing Chen , Gang Chen , Miao Huang
Published: February 2021

The terminal and the drain wire of distribution transformers are generally connected by bolts, which appears not only reliable, convenient and simple in connection and assembling, but also easy to disassemble. However, the bolt connection is prone to fail, and it is easy to loosen under force. In this paper, a bolt-free quick connection design is proposed, which introduces a large current connector plug-in structure between the voltage side terminals of the transformer and the drainage line instead of the existing bolt connection. Through the experiments performed, the performance test indicators of the large-current connector after being connected to the transformer seems to meet the requirements, and is suitable for extreme environment with humidity, dust, ultraviolet rays and other harsh, which effectively improves the flexibility and convenience of the distribution transformers operation.
Research on fuzzy control of permanent magnet synchronous motor for a mobile robot
Authors: Huanhuan Ren , Zhang Lizhong , Su Chengzhi , Jian Sun , Liu Daoxue
Published: February 2021

In this paper, a biped robot powered by permanent magnet synchronous motor (PMSM) is proposed, and each leg of the robot is a 6-degrees of freedom (DOF) parallel mechanism. Due to highly nonlinear characteristics of the leg structure, the conventional PID control strategy based on trial-error process cannot maintain the high performance of the PMSM. In order to improve the robustness of PMSM servo system and the dynamic stability of the robot, the PID controller based on fuzzy theory is developed. Fuzzy PID controller can improve the tracking accuracy and load rejection capability of PMSM, which makes the real-time system response faster without overshoot. The simulation results show that compared with conventional PID, fuzzy PID can reduce position tracking error of PMSM and deal with the external disturbance effectively.
Research on Anti-pinch Control Strategy of Window Start-up Phase based on Ripple Motor
Authors: Cheng Anyu , Long Tianci , Cheng Zhu , Liu Chang
Published: February 2021

The anti pinch area of power windows is generally 4 mm-200 mm based on ripple motor. However, the problem of excessive anti-pinch force is most likely to occur when starting at 4mm during the process of window operation. Aiming at this problems, this strategy takes current, current change rate and start-up time that can characterize the start-up phase of the window as input according to the characteristics of fuzzy control that has better recognition for unstable starting current. Then, according to the actual engineering experience is used as a fuzzy rule to make a decision on the current start-up state of the window. Finally, the state is used as the input for the anti-pinch control strategy. The compensation mechanism based on the Freeplay is added to the strategy. The current state is used to design the current threshold to realize the control of the anti-pinch force during the start-up phase. The results show that the strategy can effectively reduce the anti-pinch force in the start-up phase, it can make the anti-pinch force less than 100N and meet the requirements of GB11552-2009.
Automated COVID-19 Detection and Diagnosis Framework Based on Severity Assessment
Authors: Chen Xiaohan , Wen Hongqiao , Wu Shengzong , Lan Weishun , Zheng Rong
Published: February 2021

Computed tomography (CT) has been an important complementary indicator in the diagnosis of coronavirus disease 2019 (COVID-19). The pandemic of COVID-19 has led to a sharp increase in the number of suspected cases, which puts great pressure on radiologists. A computer-supported assisting methodology is essential to get the preliminary diagnosis regarding the pneumonia infection. In this paper, we proposed a deep learning framework for COVID-19 diagnosis and severity assessment using chest CT. The framework can not only distinguish COVID-19 patients from healthy people, but also assess the severity of patients as early or progressive stage, which makes patients with different conditions in baseline test get reasonable allocation of medical resources. The framework is composed of two modules: segmentation module and diagnosis module. Segmentation module is designed to extract the regions of interest and calculate the opacity percentage, while diagnosis module is utilized to identify suspect cases and divide them into three categories: health, early stage, and progressive stage. A total of 150 CT exams were used to train and test. An F1 score of 95.44% for COVID-19 detection and an F1 score of 90.87% for severity assessment are obtained. We also evaluated the influence of the opacity percentage calculated by the segmentation module on the classification results. By using the opacity percentage characteristic, the accuracy is improved from 94.16% to 97.42%.
Test configuration optimization method based on NSGA2-MOPSO algorithm
Authors: Yun Lin
Published: February 2021

Test configuration optimization is an important part in the process of testability design. In order to be close to the reality, this paper chooses to carry out the test optimization selection under the condition of unreliable test. Under this condition, Test configuration optimization is essentially a multi-objective optimization problem. Therefore, this paper establishes a mathematical model of the problem with test cost, test quantity and false alarm rate as optimization objectives. In this paper, the multi-objective particle swarm optimization algorithm and NSGA2 algorithm are comprehensively analyzed. According to the advantages and disadvantages of the two algorithms, NSGA2-MOPSO algorithm is proposed to solve the test optimization selection problem. The results show that the NSGA2-MOPSO algorithm has good performance and high practicability.
Missing data filling method based on linear interpolation and lightgbm
Authors: Huang Guilin
Published: February 2021

In the context of the rapid development of integrated energy and the digital transformation of power grids, data is playing an increasingly important role in the safe operation of power grids. To deepen the value of data application and ensure the accuracy of data application, this paper proposes a data filling method that combines linear interpolation and LightGBM (Light Gradient Boosting Machine) in response to the missing phenomenon in the source network data collection process. The process can generally be divided into 2 steps: First, linear interpolation is exploited to process short-term missing data. Then the LightGBM can be used to process long-term missing data. In the process of using LightGBM, linear interpolation is used to interpolate the independent variables of the input model. Through the above process, the data for the missing ratio could be obtained, which can then be used to complete all data filling in order from high to low. Through actual data test, this method has better data filling performance.
Residual life prediction of mining cables based on RBF neural network
Authors: Wu Weili , Yang Jing , Li Lei , Fan Wenling
Published: February 2021

The RBF (Radial basis Function) neural network forecasting model is constructed for the mine cable life prediction problem. According to the mine cable in line with the characteristics of accelerated life test, the temperature and the dielectric loss factor are chosen as the model input. In order to solve the problem that the number of training samples is too small and detection samples cannot be constructed, the dielectric loss factor and aging time in each temperature segment collected are linearly interpolated to generate a large number of simulation data as training target vectors, and the RBF neural network is established for life prediction. Then the predicted life value is compared with the design life of the cable for verification. The result confirms that the RBF neural network model can reflect the relationship between the dielectric loss factor and residual life under a certain humidity and the different levels of temperature, which has certain practical significance for the prediction of cable insulation life.
Application of the denoising technique based on improved FastICA algorithm in cross-correlation time delay estimation
Authors: Shi Junhe , Yan Hua , Wei Yuankun
Published: February 2021

Cross-correlation is a common time delay estimation method. However, in the actual measurement environment, the near-end and far-end sensors are often disturbed by the correlated noise, which seriously affects the accuracy of time delay estimation and even leads algorithm is proposed, and the steepest descent is introduced to reduce the sensitivity of FastICA algorithm to initial values. The useful acoustic data and disturbing acoustic data were measured respectively in a simulated granary. From these data, the signals contaminated by noise were generated by a mixing matrix and used for testing the performance of the proposed method. The testing results show that the proposed method can effectively suppress the influence of correlated noise on cross-correlation time delay estimation, and improve the accuracy of estimation.
An approach based on statistical features for extracting human actions from multivariate time series
Authors: Gui Jun , Qin Zhaobo , Jia Danping , Zhu Jianguang
Published: February 2021

Extracting system behavior from the multivariate time series collected by sensors is more challenging. If regarded people as system, the various physical actions can be considered as different states of the system. Our intention was to produce a simple, flexible and accurate method for clustering multivariate time series to obtain the system state. Previously, we proposed a distribution-based state extraction method (DBSE) that can effectively extract motion from the multivar-iate time series of human leg activities. In this paper, we propose an Auto-segmented state extraction method (AS-DBSE) by improving the size of the segmented window to adapt to more complex situations. The method uses vectors composed of statistical feature parameters to represent time series. It uses distance as the similarity measure and clusters these vectors to get the state of the system. We have proved the effectiveness and simplicity of this method through research on human arm activity data. Finally, compared with clustering based on Toeplitz inverse covariance (TICC) and symmetric non-negative matrix factorization (SymNMF), the results of the new method are more satisfactory.
Adaptive bluetooth indoor positioning system based on greedy strategy
Authors: Ding Xin , Dai Yawen
Published: February 2021

In order to solve the problem that current bluetooth indoor positioning system has low positioning accuracy in dynamic environment and can’t unable to adapt to dealing with complex situation of anchor circle, this paper proposes an adaptive bluetooth indoor positioning system based on greedy strategy. The system uses the deployed bluetooth to intelligently sense the real-time environment and measure the ibeacon signal attenuation model to reduce the ranging error caused by dynamic change of environment. In addition, the three anchor circles of the weighted centroid positioning into three groups and two different anchor circles are one group, and greedy strategy is used for getting the better weighted objects when each group of circles are intersected, or separated, or contained. Finally, the sum of the reciprocal radius of each group of anchor circles is used as the weight to obtain the estimated coordinates of unknown nodes. To verify the effectiveness of the positioning system by case study, the results show that the average error value is 0.60m. Compared with the centroid localization algorithm and weighted centroid algorithm, the system has the advantages of intelligent environment perception, higher positioning accuracy, and adaptive algorithm for dealing with various situations of anchor circle.
Grasping Prediction Algorithm Based on Full Convolutional Neural Network
Authors: Feng Kaiyue , Wei Wu , Yu Qiuda , Liu Qinglun
Published: February 2021

Robot grasping is a very frontier and important research direction in the field of robotics. In order to solve the problem of the robot's real-time capture, reduce the time of the visual processing, we proposed a two-stage Convolutional Neural Network structure whose design is simple, with less training parameters, improving the efficiency of the visual system. Using rotation and translation to expand the Cornell fetching dataset. The best model at Cornell grasp test set has achieved 88% of forecast accuracy compared with 73% accuracy rate on one stage network. Moreover, our model size is 0.51MB, speed at 30 FPS on GPU inferencing.