bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of high temperature degaussing on lifting capacity of linear motor reciprocating pump
Authors: Jian Cheng , Ma Lei , Yang Weifeng , Huang Qing , Xu Jing , Zhai Huan , Cao Guangsheng
Published: December 2021

The submersible linear motor reciprocating pump is a new type of artificial lift. The degaussing effect of its permanent magnet at high temperature will reduce the lifting capacity of the linear motor reciprocating pump. In this paper, the thermal stability of NdFeB permanent magnet material was studied by simulating the underground temperature and pressure conditions in a high-temperature and high-pressure reactor and combining with a Tesla instrument. The results show that NdFeB material loses its magnetism rapidly at high temperature, and the residual magnetism is proportional to the ambient temperature of the magnet. The high temperature demagnetization effect of large magnets is more serious due to eddy current loss and hysteresis loss.
Treatment of ultrahigh chemical oxygen demand chemical wastewater by Fenton oxidation
Authors: Xue Xingfu
Published: December 2021

The article focuses on the Fenton oxidation process for the treatment of ultrahigh COD chemical wastewater from chemical plants. Optimum pH was determined as 2.0 and 10.0 for the first (oxidation) and second stage (coagulation) of the Fenton process, respectively. 0.465gFeSO4·7H2O, H2O2(30%)2ml, the mole tatio of H2O2 : Fe2+=10:1, adjust the pH of the solution to 10, after 1.5 hours of agitation, then add 5% PAM2ml to the solution, filtrate, extract, filtrate the clear liquid and dilute it three times, take 200ml of the diluted liquid, and add 0.465gFeSO4·7H2O, H2O2(30%)2ml, the mole tatio of H2O2 : Fe2+=10:1, adjust the pH of the solution to 10, after 1.5 hours of agitation, then add 5% PAM2ml to the solution, static stratification. For chemical wastewater, when the molar ratio H2O2/Fe2+ is 10:1, the removal rate of COD is the highest, provided 86.21–86.45% COD removal.
Research on Performance Evaluation of PPG/Polymer Flooding System
Authors: Cao Ruibo , Yan Wei , Pi Yanfu , Liu Jinxin , Chen Hao
Published: December 2021

Aiming at the PPG/polymer flooding system developed by Daqing Exploration and Development Research Institute, this paper conducts research on its viscosity increasing, viscosity stability, rheological properties, viscoelasticity and seepage ability. The experimental results show that:PPG has a thickening effect on the system, and the thickening range is between 37% and 66%;the viscosity retention rate of the PPG/polymer system is higher (88%) than the ordinary 25 million polymer solution (75%) ); Under the same shear rate conditions, the apparent viscosity of the PPG/polymer system is higher than 25 million pure polymer; the PPG/polymer system has a resilience effect, and its G’ and G” values are greater than that of a pure polymer solution;PPG/The polymer system can migrate to the deep part of the oil layer and still maintain high seepage resistance, which can realize deep profile control.
Exploration on the Materials Quality Control of Railway Vehicle Weld Structure Based on Service Safety Demand
Authors: Wang Jianing , Wu Zezhou , Han Bin , Zhang Tao , Zhou Baosheng , Song Kunlin , Jin Xiao , Ren Songzan , Chen Jiarong , Zhao Xin’e
Published: December 2021

With the continuous increasing of service-rail-vehicle in China, some defects such as cracks appeared at different stages of service when they had not reached the design life, while current theories and methods cannot explain the appearance of defects, which brought risks and hidden dangers to the operation of the vehicles. It was found that the reasons were mainly caused by one or several factors such as material performances, design, manufacturing process and operating environment. Since more and more sensors being installed on the vehicles to supervise the health of structure, it is more improtant to focus on the performances of materials. Through comparing different material standards including international, national, railway industry and enterprise standards, as well as the technical delivery conditions of other industries, it was recommended that the fracture mechanical parameters such as fracture toughness and fatigue crack growth should be proposed into the materials quality control regulations of original equipment manufacturers (OEMs). Furthermore, based on the testing data of materials from OEMs, several suggestions were proposed on the basic performance of materials such as raising the requirements contained impact, metallography and corrosion resistance properties in order to provide guarantee for the service safety of vehicles.
Research on Perfect and Tunable Metamaterial Absorber Based on Crosshair-shaped Graphene
Authors: Guo Yiran , Qi Yunping , Liu Chuqin , Liu Weiming , Wang Xiangxian
Published: December 2021

Graphene, as a new nano-material, according to the physical properties of electric field localization and selective absorption on light of surface plasmon resonance (SPR), a tunable, multi-band and wide-angle perfect absorber based on crosshair-shaped graphene is devised by using the Finite Difference in Time Domain (FDTD) method. In this paper, the effects of chemical potential, relaxation time, and incident angle of light on the absorptivity of graphene are systematically discussed. The simulation experiment shows that there are two absorption peaks with perfect absorption rate appeared in the study range, and the maximum modulation index can be obtained by changing the relaxation time. Finally, it proves that the absorber is insensitive to wide-angle of light. Thus, it is able to be concluded that the absorber has a great reference value to sensor, wireless communication, biomedical and other fields.
Interfacial Thermal Conductance between Alumina and Epoxy
Authors: Yang Wei , Wang Kun , Fu Yongsheng , Zheng Kun , Chen Yun , Ma Yongmei
Published: December 2021

Interfacial thermal conductance (ITC) of inorganic/epoxy interface is regarded as one of the most significant factors in determining thermal transport performance of epoxy composite. Here, ITC between alumina and epoxy was experimentally investigated by time-domain thermoreflectance (TDTR) method. The results show that the ITC is effectively increased from 9.0 MW m-2 K-1 for non-treated alumina/epoxy interfaces to 26.3 MW m-2 K-1 for plasma treated interfaces. This work sheds some light on design and application for thermally conductive composites.
Optimization of injection parameters for temperature time response gel plugging agent
Authors: Yan Wei , Cao Ruibo , Ma Yingxue
Published: December 2021

Aiming at the temperature time response gel plugging agent developed by Daqing exploration and development institute. In this paper, the injection volume, injection speed and injection concentration are optimized. The experimental results show that: the temperature time response gel can achieve the best plugging effect under the injection volume 0.1PV, injection concentration 1000mg/L and injection speed 0.6ml/min. In the subsequent water injection stage, the conductivity of high permeability layer decreases from 72.7% to 0.7%, that of low permeability layer increases from 4.1% to 14.3%, and that of medium permeability layer increases from 23.2% to 85%.
Preparation and characterization of red mud based porous materials
Authors: Zhu Junge , Yue Hongzhi , Bai Rong , Zhu Jianping , Ma Laijun
Published: December 2021

China was a large country in bauxite mining and refining. One ton of alumina was produced, accompanied by 0.5 ~ 2 tons of red mud [1]. Therefore, the accumulation and pollution of red mud had been a difficult problem to be solved by enterprises and local governments. In this paper, red mud based porous materials were prepared with Bayer red mud, perlite, silicon carbide (as foaming agent) and glass powder (as flux). The effects of sintering process and iron oxide on thermal conductivity, bulk density, porosity and compressive strength of red mud based porous materials were studied by TG-DSC, XRD, SEM and XEDS. The results show that red mud based porous materials with uniform pore distribution could be obtained when the amount of red mud was 60%, perlite was 37%, SiC was 1%, glass powder was 2%, sintering temperature was 1150 °C and holding time was 120 min. The true porosity of the red mud based porous material was 70%, and the average pore diameter was 216.84 μ m. The thermal conductivity was 0.26w / (m • K) and the compressive strength was 2.31MPa.
Process Characteristics of Water-based Self-curing Coatings for Sand Casting
Authors: Bian Qingqing , Feng Shengshan , Dong Huang , Xie Shuzhong , Liu Chunjing , Zhan Chunyi , Chen Jianli , Wu Weifeng , Liang Jiahao , Gao Yunhua
Published: December 2021

The rheological and gas evolution characteristics of water-based self-curing coatings for sand casting were analyzed and the influence of coating-thickness and graded coating on self-curing rate of coatings was studied. It can be seen from the test results that: the new water-based self-curing coating has both the characteristics of thixotropic fluid and pseudoplastic fluid, which has moderate thixotropy rate and high brushing index, good brushability and excellent comprehensive balance of flow-levelling and anti-flowability. It can meet the rheological requirements of various coating methods. The self-curing speed of water-based self-curing coating increases in an approximately linear manner with the decrease of its thickness. Thick coating should be best to paint at one time in the premise of ensuring its surface quality. Although the gas evolution volume of the new water-based self-curing coating is approximately equal to that of ordinary water-based baking coatings, but the gas evolution speed of self-curing coatings is almost half as that of the latter, which provides good conditions for preventing gas hole defect of casting.
Research on Discrimination Threshold of Brightness for Different Color Temperatures
Authors: Ju Jiaqi , Xu Ting , Xu Ke , Jin Yan
Published: December 2021

This article explores the experimental study on the relationship between human eye discrimination threshold of white light under different lighting levels and color temperatures by the psychophysical experimental method. The visual matching method was applied to study the subjective brightness perception under different lighting environments. We try to explore the internal connection between the physical intensity and subjective rating value. The experimental results will do help the development of dimming system for smart lighting.
Autocorrelation Measurement of Picosecond Pulses with Two-Photon Absorption
Authors: Chen Junbao , Yang Yitao , Qiu Mingyue
Published: December 2021

In this work, an autocorrelation measurement method is proposed to obtain the key information of picosecond pulses using the two-photon absorption (TPA) effect. The autocorrelation measurement process is simulated with a linear tuning of the pulse repetition frequency (PRF). Given the dispersion of picosecond pulses, the profile of the autocorrelation signal is broadened symmetrically. Moreover, the dispersive distribution in time-frequency domain of picosecond pulses and the different bandwidth of the TPA spectrum of materials should bring in sub pulses in the autocorrelation signal with the relative different delay. As shown in simulations, with an ideal broadband two-photon response spectrum, only the broadening of autocorrelation trace appears. But the detection with a narrowband two-photon response spectrum displays the greater sensitivity for pulse dispersion of the edge of the pulse, benefiting from the more sub pulses. Detections of picosecond pulses within the space wireless communication band region generally employ the photoconductive antenna and electro-optic effect in free space. However, with respect to the TPA effect in the specific materials, we could build an extremely compact autocorrelation measurement configuration for the key information extraction of picosecond pulses in space wireless communication and astronomical measurement, which would provide the same information as conventional detections about the autocorrelation signal of picosecond pulses.
Effects of the Photoelectrochemical Etching in Hydrogen Fluride (HF) on the Optoelectrical Properties of Ga2O3
Authors: Hao Yuhua , Wang Xia
Published: December 2021

Photoelectrochemical (PEC) etching is preferred to produce micro-and nano-structures for constructing Ga2O3-based electronics and optoelectronics, owing to its numerous controllable parameters. During the devices fabrications, beyond the wet chemical and dry (plasma) etching produces, PEC etching also leads to device degradations inordinately. In this work, the Ga2O3 thin film was PEC etched by hydrogen fluride (HF) etchant, and its opto-electric deep-ultraviolet sensing performances, including photo-to-dark current ratio, responsivity, and response speed, before and after PEC etching were analyzed and discussed.
Optical Design of Improved Offner Imaging Spectrometer
Authors: Song Chong , Huang Yong , Yan Yangdong , Cui Dongsen , Wang Gang , Niu Yanting , Liu Bijun
Published: December 2021

An improved Offner imaging spectrometer was proposed based on the optical system characteristics of Offner imaging spectrometer, which can ensure perfect imaging quality in a wider annular region. The operating wavelength of the improved Offner imaging spectrometer ranges from 900nm to 1700nm, and the magnification is 1. Improved Offner imaging spectrometer can be obtained by changing the meniscus lens position and further optimizing the design. The results indicate that the improved Offner imaging spectrometer can effectively improve compactness and lightweight, and reduce the difficulty of optical adjustment, which is conducive to the stability of practical application.
Haze-day Trends from 2013 to 2020 and Analysis of Spatiotemporal Characteristics of a Haze Process in Ningbo, China
Authors: Hu Lijun , Gao Aizhen , Yang Hao , Zheng Zheng
Published: December 2021

Air quality in Ningbo continues to improve with a constant decrease in the PM2.5 concentration. However, pollution levels occasionally increase during autumn and winter. To understand the regional and seasonal distributions and the interannual variation during haze days, we analyzed the haze monitoring data from 2013 to 2020 and the haze weather process during January 18–19, 2016. Our results showed a downward trend in the major pollutant concentrations. High PM2.5 concentrations persist in certain areas of Ningbo during winter owing to seasonal haze conditions. However, the annual number of haze days has decreased between 2013 and 2020. Regional variations in pollutant concentrations appear mainly in winter, especially in December and January. The observed concentrations were higher in the north and west, and lower in the south and east. The haze process during January 18–19, 2016, occurred within a height of 0–1.5 km, with high PM2.5 concentrations mainly occurring as small and spherical particles. A higher relative humidity, temperature drop, and stable weather assist in accumulating and sinking pollutants, which cause long-term effects and render diffusion difficult. Although recent national initiatives have been effective, the air quality in northern Ningbo requires further improvement during autumn and winter.
The Influence of Noise in the Super-Resolution Reconstruction of Structured Illumination Microscopy
Authors: Bai Jinxi , Shi Zhendong , Ma Hua , Liu Lijia , Zhang Lin
Published: December 2021

As one of the mainstream super-resolution imaging technologies, structured illumination microscopy (SIM) is popular for its fast imaging speed and simple optical path structure. Spectrum separation is a key step in the reconstruction of super-resolution images. However, in the process of imaging, the unavoidable noise will seriously affect the accuracy of frequency spectrum separation. This paper carries out a simulation study on the influence of noise in the process of frequency spectrum separation. The results show that although noise can cause distortion of low-frequency information in frequency spectrum separation results, it has little influence on high-frequency information. Therefore, a super-resolution image reconstruction method is proposed to effectively suppress the influence of noise. Both simulation and experimental results are shown the method can suppress the influence of noise without losing the details of super-resolution.
Joint Monitoring and Analysis of Sea Fog Using Dual Visibility Lidar in Ningbo, China
Authors: Hu Lijun , Yang Hao , Wang Hao , Ren Xinyue
Published: December 2021

Visibility lidar has obvious monitoring advantages over forward scatter visibility sensors or fog droplet spectrometers; it can measure visibility information over a large area. In 2021, two visibility lidar instruments (1064 or 532 nm wavelengths) were installed in Beilun, Ningbo Zhoushan Port, to monitor sea fog. Comparing their monitoring data to those of forward scatter visibility sensors and a fog droplet spectrometer revealed that the visibility lidar instruments could obtain energy progress information section-by-section in the monitoring path, and could directly reflect sea fog changes. The 1064 nm lidar outperformed the 532 nm lidar regarding sea fog detection. The effective detection range decreased significantly with decreasing visibility; the reliability decreased in low-visibility, uneven atmospheres. In a low-visibility but uniform atmosphere, however, lidar data corresponded well with forward dispersion data. The 532 nm and 1064 nm lidar data sometimes differed at the same monitoring position owing to differing heights and particle reflection angles. During a sea fog event on May 9, 2021, the maximum droplet concentration was 14 cm−3, the maximum liquid water content was 0.21 g·m−3, and the maximum equivalent diameter was 49 μm. The formation of this sea fog was dominated by large particles.
Active Disturbance Rejection Control Based Feedback Control System for Quasi-Continuous-Wave Laser Beam Pointing Stabilization
Authors: Li Wenjun , Zhang Lin , Guo Yading , Chen Zhongzheng , Shao Chongfeng , Li Yang , Chang Jinquan , Chen Na , Wang Xiaojun , Bo Yong , Peng Qinjun
Published: December 2021

Because of the significant nonlinearity of fast steering mirror (FSM), which is actuated by lead zirconate titanate (PZT) stacks, designing a high-performance laser beam pointing stabilization system is always a difficult work. This paper reports an active disturbance rejection control (ADRC) based feedback control system for laser beam pointing stabilization of a high-power quasi-continuous-wave (QCW) Nd:YAG slab laser with a repetition frequency of 160 Hz and an average output power of 1.5 kW. The simulation and experiment show that the ADRC is faster and smoother than traditional proportional-integral-differential (PID) control, and the ADRC can effectively reduce overshoot in the laser beam pointing stabilization process.
Representative Construction Engineering Drawings Combining SLAM and Ground-Based LiDAR
Authors: Gao Chutian , Guo Ming , Fu Zexin , Li Dengke , Ren Xian , Sun Mengxi , Zhou Yuquan , Cheng Peng
Published: December 2021

Obtaining architectural engineering drawings is a crucial aspect of upgrading and repairing structures. Traditional elevation measuring is ineffective and results in a poor rate of restoration. The current building elevation measurement solutions based on 3D scanning technology all obtain building 3D point cloud data from a single type of laser scanner. These two methods can’t get both indoor and outdoor scenes at the same time. This paper presents a scanning strategy that combines SLAM with Ground-based LiDAR to solve this problem. The point cloud data for the building’s indoor and outdoor scenes are obtained independently, and the Ground-based LiDAR point cloud data is registered locally using the iterative closest point(ICP) algorithm. The SLAM point clouds and the Ground-based LiDAR point clouds are then registered as a whole to develop an overall model of the building using point constrained error equations. For various reasons, the building can be trimmed into a planar point cloud model depending on the application. Finally, engineering drawings for the construction of the building can be drawn. The method’s viability was demonstrated by using it in a 3D scanning project of a scenic site in Beijing. This technology improves model information interpretability, scanning efficiency, and provides powerful data assistance for building rehabilitation and repair. It is extremely important in the disciplines of urban planning, rehabilitation, and historic preservation. After performing a more optimal preprocessing, more than 90% classification accuracy was achieved across 18 low-power consumer devices for scenarios in which the in-band features-to-noise ratio (FNR) was very poor.
Design and simulation analysis of vacuum fish suction pump
Authors: Ding Ziyang , Xu Lingfeng , Gao Ming , Wang Guoqing
Published: December 2021

Most of Chinese aquacultural products rely on artificial nets to catch in 2020. Fish suction pump can replace artificial net, is an important mechanical equipment of fish breeding industry. The development of fish suction pump is relatively backward and the level of automation is still to be improved, which is not conducive to the large-scale and rapid development of aquaculture in various countries. This paper designs a single tank vacuum suction fish pump, the suction fish pump mainly uses the tank and the air pressure difference, through the automatic control system on the suction fish pump and each stage of the control, relying on the gravity of the mixture of fish and water to release fish. In this paper, fluent was used to conduct simulation analysis on the flow diagram of fish-water mixture inhaled at work, and the flow diagram and velocity vector diagram of the internal flow field were obtained. The results show that the vacuum fish suction pump can effectively reduce the fish collision damage. The vacuum fish suction pump designed in this paper can effectively complete the fishing work of cultured fish, with the characteristics of high efficiency and low damage, which can provide theoretical reference for the design of vacuum fish suction pump in the future.
Estimation of Vehicle Longitudinal Speed Based on Improved Kalman Filter
Authors: Zhang Qiang , Xiao Jun , Xi Xiuhao
Published: December 2021

Estimation of vehicle longitudinal acceleration is very important in vehicle active safety control system. In this paper, two driving conditions of a 4WD off-road vehicle are divided by vehicle signals such as steering angle. Under different working conditions, different estimation algorithms are adopted. In the straight driving condition, the longitudinal speed was estimated by adjusting the variance weight of acceleration Kalman observation noise based on kinematics method. For steering conditions, in order to obtain the longitudinal velocity at the center of mass, by dynamic method, a lateral state estimator was designed and tire sideslip dynamics was modeled. The CarSim-Simulink co-simulation results show that the proposed algorithm has high accuracy and strong practicability.
Internal Leakage Predicition of Hydraulic Spool valves Based on Acoustic Emission Technology
Authors: Song Fei , Peng Likun , Chen Jia , Wang Benmeng
Published: December 2021

In order to realize the nondestructive testing (NDT) of the internal leakage fault of hydraulic spool valves, the internal leakage rate must be predicted by AE (acoustic emission) technology. An AE experimental platform of internal leakage of hydraulic spool valves is built to study the characteristics of AE signals of internal leakage and the relationship between AE signals and leakage rates. The research results show the AE signals present a wideband characteristic. The main frequencies are concentrated in 30~50 kHz and the peak frequency is around 40 kHz. When the leakage rate is large, there are significant signal characteristics appearing in the high frequency band of 75~100 kHz. The exponent of the root mean square(RMS) of AE signals is positively correlated with the exponent of the leakage rate only if the leakage rate is greater than 2~3 mL/min. This find could be used to predict the internal leakage rate of hydraulic spool valves.
Design of the LADRC control system for gravimetric stabilisation platforms
Authors: Lin Enfan , Xu Jiangning , Wu Miao , He Hongyang
Published: December 2021

Aiming at the problems of strong non-linearity of gravimeter stabilisation platform system, poor robustness of linear PID control algorithm and non-adaptive control system. This paper designs a LADRC-based gravimetric stabilisation platform control system design and method based on the research of PID controller and ADRC control method, and gives the anti-saturation and anti-noise design applicable to it, and the simulation experiment shows that the method is feasible.
Magnetic Target Position Estimation Method Based on Prior Information
Authors: Sun Guangfa
Published: December 2021

Aiming at the problem of detection and location of magnetic targets in water beach, the acoustic magnetic composite detection method is studied. After the sonar obtains the image of the suspicious object in the target area, the magnetic target recognition and location are realized by using the abnormal magnetic field distribution data near the target area measured by the shipborne magnetic sensor and the multi-sensor information fusion method. A target recognition and location method based on a priori information is proposed to solve the problem that the measurement results of magnetic sensor can not fully reflect the influence of ferromagnetic target on the surrounding magnetic field due to terrain constraints. In order to make up for this lack of information, taking the sonar measurement results as a priori information, the hypothesis test method is adopted to make full use of all the measurement results of different types of sensors to realize the recognition and positioning of magnetic targets.
Study on dynamic characteristics of rotor-bearing system under pitching condition
Authors: Pu Songcheng , He Yumin , Yang Qijiang , Cheng Ming , Wang Yupeng , Wang Zheng , Lin Yaodi
Published: December 2021

In many cases, ships will encounter special conditions, such as bad sea conditions, and the effect of various disturbance factors, such as wind and waves, will cause low-frequency longitudinal and transverse rocking motion of ships. This would affect the rotor-bearing system of the power plant, which is directly attached to the hull of the ship, and would roll along with the hull in the same longitudinal and transverse motion. This will have a significant impact on the stability of the rotor bearing system of the ship power plant and the safety of the ship. In this paper, a rotor-bearing test rig is mounted on a multi-degree-of-freedom swing test rig simulating sea conditions. The multi-degree-of-freedom rocking test bed simulates sea conditions. The rotor-bearing test bed is equipped with an eddy current sensor and an acceleration sensor to obtain experimental data. The programmable loader is used to control the rotor speed so as to carry out the experiment process at different speeds. Finally, the dynamic characteristics of rotor-bearing system under swinging condition are obtained.
Solving Multiple Triggering Problem of Ultrasonic Distance Measurement by Debouncing
Authors: Xiang Zhenhua
Published: December 2021

In recent years, multiple measurement systems fusion technologies have developed rapidly. Ultrasonic ranging is paid much attention because it has the advantages of directly measuring short-distance targets, high longitudinal resolution, and a wide application range. However, when the ultrasonic distance measurement is carried out by assembling the circuit board, it is found that the switch is triggered multiple times, and the measurement data is inaccurate. This paper proposes a new method that adding debounce to improve the accuracy of measurement. Besides, Some suggestions are provided to decrease the operation difficulty in the actual measurement process. Based on the experimental result, the accuracy and efficiency of ultrasonic distance measurement are greatly improved via this method proposed in this paper. By the way, the single-chip computer simulation technology simulates the ranging phenomenon in the experiment.
Research on Frequency Characteristics of VSG Virtual Parameter Adaptive Control Strategy Based on Fuzzy Control Theory
Authors: Jin Jie , Li Lan , Yu Haiyang , Feng Shengzhou
Published: December 2021

Traditional virtual synchronous generators (VSG) control inverters. Inverter output frequency characteristic of the virtual inertia (J) and virtual damping (D) coefficient, and the virtual parameters need to be modified and adjusted according to the purpose. To solve this problem, this paper proposes a virtual parameter adaptive control strategy based on fuzzy control theory to adjust the frequency characteristics of VSG. MATLAB/Simulink is used to build a simulation model to verify the correctness of the proposed fuzzy control theory’s adaptive virtual parameter theory.
Development of a 125% Load Brake Test Instrument for Elevator
Authors: Zhang Pengzhao , Feng Shuangchang , Fang Liang , Liu Shengjie
Published: December 2021

In order to solve the problem of elevator braking test inspection, this paper combs the requirements of relevant national standards and inspection rules on braking performance, and develops an elevator braking test inspection instrument. With the help of the instrument, the elevator braking effect can be expressed quantitatively, and the inspectors can conveniently judge whether the braking test results meet the requirements of elevator inspection rules remotely. A way to standardize and rationalize the test is given. In order to solve the problem of elevator brake test inspection, this paper sorted out the national standards and inspection rules on braking performance, and developed an instrument of elevator brake test inspection. With the help of the instrument, we could quantitatively give the expression on the elevator braking effect, and the inspectors can conveniently judge whether the braking test results meet the requirements of the elevator inspection rules in the remote.
Research on dynamic current sharing method of parallel connected IGBT modules for NPC three level converters
Authors: Peng Xi , Yin Sheng , Zou Yingqin
Published: December 2021

The parallel connection of IGBTs has been being applied in high power neutral point clamped (NPC) three level converters. This paper investigates the impact of gate parameters (gate resistor and capacitance) on dynamic current imbalance of parallel connected IGBT for NPC three level converter. A gate parameters calculation method is proposed in the paper, and the delay time and collector current difference can be analysed quantitatively. Experimental results have shown the effectiveness of the method.
Design of Smoke Alarm Disperser Based on Single-chip Microcomputer
Authors: Wang Yang , Han Lichun , Zhao Yonghui , Xue Yuquan , Wang Liming
Published: December 2021

With the rapid development of society and economy, various laboratories have become more complete in number and equipment, but subsequent laboratory accidents frequently occur. Therefore, it is imperative to construct a laboratory safety management system to ensure the safety of laboratory personnel and complete equipment. This article intends to design a smoke alarm, which mainly includes measuring the sensitivity of the smoke sensor to the concentration of smoke in the air, and the linear change of the sensor converting the corresponding analog signal into a digital signal. By designing the fan speed to be controlled by the change of smoke density, the speed of the motor is adjusted. And the alarm module can sound an alarm when the smoke concentration is certain, and at the same time, it can automatically cancel the alarm when the smoke concentration decreases. Finally, a simulation experiment is designed to simulate the effect of the sound alarm of the smoke alarm disperser on the dispersal of smoke under different working environments.
A design of laser array harp based on multi-dimensional wavelet transform and audio signal reconstruction
Authors: Liu Bin , Ren Yan
Published: December 2021

This paper introduces a design scheme of laser array harp based on multi-dimensional wavelet transform and audio signal reconstruction. The green light beams from multiple high-power lasers simulate harp strings, use photoresistors as the signal receiving end, and use a signal conditioning system composed of analog circuits and LM393 comparators to collect and adjust the resistance signal of the laser sensor[1], and finally it is adjusted to a level signal that can be recognized by the CPU. After receiving the signal, the CPU core board analyzes the string signal, and sends control commands to the audio processing system through the industrial bus according to the analyzed digital signal. After receiving the control command, the audio processing system uses the audio signal reconstruction technology composed of multi-dimensional wavelet packets, deep learning and other algorithms to simulate the audio signals of various string music, so as to achieve the purposes of using the lasers as virtual strings and imitating musical instruments for musical performance.[2]
Research on 5G positioning technology for urban canyon
Authors: Xiong Xin , Liu Shumin
Published: December 2021

Aiming at the problem of poor positioning accuracy of GNSS for urban canyon environment, this paper proposes a TDOA/AOA combined positioning technology based on 5G.Firstly, the AOA estimation algorithm based on conventional beam forming is compared with that based on MUSIC algorithm. Then, the weighted matrix is smoothed forward and backward.Finally, according to the measurement data of AOA and TDOA, Chan and Taylor combined localization algorithm is used to obtain the estimated location of the user.
GAN Image Generation and Detection Technology Based on Fractal Dimension
Authors: Guo Yuheng
Published: December 2021

With the development of modern technology today, image analysis technology has become an important research direction in the computer field. Computer image processing technology is a cross and fusion involving multiple disciplines, which includes multiple research directions such as physics, chemistry, and computer science. Starting from the fractal dimension, this article studies the image generation and detection technology. The purpose of the research topic in this article is to have a deep understanding of image generation technology so as to master image processing methods proficiently. The methods used in this article include case analysis, data, comparison, and experimental methods, etc., and carry out related researches on image generation detection technology and fractal dimension. The experimental results show that the algorithm accuracy of GAN in the detection technology of computer-generated images is higher than other algorithms, and the improvement space is about 0.06.
Comparative analysis of dynamic state recognition between permutation entropy and weighted permutation entropy
Authors: Luo Wenxiang , Wan Li , Liu Hui
Published: December 2021

Permutation entropy (PE) and weighted permutation entropy (WPE) are indexes of the complex system. In this paper, the nonlinear sequence of two chaotic states is simulated by Logistic mapping, and the effectiveness of the PE and WPE algorithms in chaotic state recognition is compared and analyzed with different sliding step sizes. The results show that the value of WPE changes more obviously than PE in different chaotic states, and the recognition effect of WPE is better than PE in dynamic states, which can provide theoretical support for further analyzing the complexity characteristics of actual data.
Ship classification based on random forest using static information from AIS data
Authors: Wang Yitao , Yang Lei , Song Xin , Li Xuan
Published: December 2021

With the wide use of automatic identification system (AIS), a large amount of ship-related data has been provided for marine transportation analysis. Generally, AIS reports the type information of ships, but there are still many ships with type unknown in AIS data. It is necessary to develop algorithms which can identify ship type from AIS data. In this paper, we employ random forest to classify ships according to the static information from AIS messages. Moreover, the importance of static features is discussed, which explains the reason why some classes of ships are misclassified. The method of this paper is proved to be effective in ship classification using static information.
Research on intelligent early warning system of rail transit line trip based on pscada
Authors: Zhang Yuqing , Zhang Xiaohong
Published: December 2021

In this paper, an intelligent early warning scheme for rail transit line trip based on PSCADA system is proposed. The scheme takes into account the defects of low prediction accuracy and real-time prediction caused by the lack of power data in the traditional line trip prediction method. At the same time, a large number of power data generated by PSCADA system in the long-term application process are ignored in the field of rail transit[1]. Based on this situation, the prediction data set is constructed by combining the historical power data collected by PSCADA system in rail transit and the lightning weather data in traditional prediction methods. On this basis, the lightgbm machine learning intelligent algorithm is used to compare the similar support vector machine (SVM) and logistic regression algorithm to obtain a model with good prediction effect. In practical application, the real-time data set is constructed by using the real-time power data and real-time weather data collected by PSCADA system to predict, and an intelligent early warning system with the dual advantages of real-time and high accuracy is obtained.
Finger joint angle estimation based on sEMG signals by Attention-MLP
Authors: Yu Zhebin , Wang Hui , Yu Wenlong
Published: December 2021

sEMG(Surface electromyography) signal was widely applied in human-machine interactive field, especially in robotic arm control. In this paper, we built the Attention-MLP (Multilayer Perceptron) model to implement a type of continuous joint angle estimation method based on sEMG for six grasp movements, we tested this model on Ninapro dataset and the average Pearson correlation coefficient (CC) and the average root mean square error (RMSE) of the proposed Attention-MLP method achieved 0.812±0.02 and 10.51±1.98; the average CC and RMSE of this method are better than Sparse Pseudo-input Gaussian processes (SPGP), its average CC and RMSE are 12.14±2.30 and 0.727±0.07. Compared with the traditional method SPGP, our model performed better on continuously estimation of ten main hand joint angles under 6 grip movements.
Identifying important nodes from content-associated heterogeneous graph by LeaderRank
Authors: Dai Yulong , Shen Qiyou , Xu Xiangqian , Yang Jun
Published: December 2021

Most real-world systems consist of a large number of interacting entities of many types. However, most of the current researches on systems are based on the assumption that the type of node or link in the network is unique. In other words, the network is homogeneous, containing the same type of nodes and links. Based on this assumption, differential information between nodes and edges is ignored. This paper firstly introduces the research background, challenges and significance of this research. Secondly, the basic concepts of the model are introduced. Thirdly, a novel type-sensitive LeaderRank algorithm is proposed and combined with distance rule to solve the importance ranking problem of content-associated heterogeneous graph nodes. Finally, the writer influence data set is used for experimental analysis to further prove the validity of the model.
A simplified algorithm for 3D mesh model considering the influence of edge features
Authors: Lv Rumeng , Chen Xiaobing , Zhang Bingying
Published: December 2021

Aiming at the problem that most of the existing grid simplification algorithms for 3D models can not deal with a large number of boundary or non-popular grid models, this paper proposes a grid simplification algorithm for 3D models based on traditional algorithms. The algorithm mainly studies the geometric features of the model, considering the calculation methods and characteristics of edge shrinkage, and introduces the edge feature factors on the basis of the traditional algorithm, that is, the triangular area and side length factors of local area are introduced in the calculation of folding cost. In addition, the gaussian curvature characteristics of the 3D model are also included. Experimental results show that the proposed algorithm can keep the detail features of the mesh model well, and greatly reflect the quality and effect of mesh simplification after simplification.
Discussion on Remote Monitoring and Fault Analysis Technology of Mechanical Manufacturing Equipment
Authors: Guo Pengyu
Published: December 2021

Due to the interference of external factors, it is essential to adopt scientific and reasonable remote monitoring methods in mechanical manufacturing. Remote monitoring can ensure the efficiency of abnormal data acquisition, identify faults, improve equipment efficiency, save maintenance time, prolong service life, improve efficiency, and ensure the service life of machine production equipment. Therefore, it is necessary for the subordinate departments to effectively combine the actual situation and introduce some advanced technologies to effectively identify the remote controller and faults and ensure the regular and stable operation of the machine.
Rolling bearing fault diagnosis based on MEEMD sample entropy and SSA-SVM
Authors: Li Xuguang , Fu Liyou
Published: December 2021

The penalty parameter (c) and kernel parameter (g) contained in Support Vector Machine (SVM) cannot be adaptively selected according to actual samples, which results in low classification accuracy and slow convergence speed. A novel sparrow search algorithm was used to optimize the parameters of SVM classifier. Firstly, an improved ensemble empirical mode decomposition (MEEMD) method was used to decompose non-stationary and nonlinear vibration signals, and the eigenmode function (IMF) was obtained by removing abnormal signals from the original signals through permutation entropy, and the sample entropy was extracted. Finally, a fault diagnosis model based on SSA-SVM is constructed, and the high recognition rate and effectiveness of this method are proved by simulation and experimental data analysis.
Dual Fano Resonances Induced by Rectangle-based Plasmonic Resonator for Refractive Index Nano-sensor
Authors: Zhang Yang
Published: December 2021

A tunable dual Fano-like plasmonic structure consisting of metal-insulator-metal (MIM), baffle and a rectangular cavity containing two identical rectangular metal blocks is obtained. Numerical simulation results show that there are dual Fano resonances in the transmission spectrum of the structure, which can be tuned by changing the geometric parameters of the structure. In addition, due to the apparent asymmetry of the Fano resonances, the system was developed as an effective refractive index sensor (RIS) with a sensitivity of 853 nm/RIU and figure of merit (FOM) of 1631. It is considered that this structure has important application value in high integrated photonic circuit.
Research on position offset compensation of underwater manipulator
Authors: Ren Shanbin , Zhang Hui , Li Kai , Cheng Yujun , Liu Xin , Duan Derong
Published: December 2021

A compensation method for end position offset of underwater manipulator is presented in this paper. Firstly, the end deformation of the underwater manipulator is obtained by ANSYS analysis, and then the end position offset equation is obtained by MATLAB curve fitting. Finally, the equation is added to the kinematic model of the underwater manipulator, which improves the accuracy of the kinematic model of the underwater manipulator and lays a foundation for the accurate position control of the underwater manipulator.
Short-term wind power prediction based on hybrid variational mode decomposition and least squares support vector machine optimized by improved salp swarm algorithm model
Authors: Su Zhongde , Lu Huacai
Published: December 2021

To improve the accuracy of wind power prediction, a short-term wind power prediction model based on variational mode decomposition (VMD) and improved salp swarm algorithm (ISSA) optimized least squares support vector machine (LSSVM) is proposed. In the model, the variational modal decomposition is used to decompose the wind power sequence into multiple eigenmode components with limited bandwidth. The improved salp swarm algorithm is employed to tune the regularization parameter and kernel parameter in LSSVM. The proposed wind power prediction strategy using mean one-hour historical wind power data collected from a wind farm located in zhejiang, China. Compared with other prediction models illustrate the better prediction performance of VMD-ISSA-LSSVM.
Numerical research on thermal stress of steam cooler tube sheet mechanical structure
Authors: Wu Jun , Zheng Zhaoli , Li Yong , Pang Jie , Ke Zhiwu , Zhang Nan
Published: December 2021

Steam cooler is one of the most important mechanical equipment in thermal power generation system and nuclear power generation system. The steam cooler bears a huge temperature gradient load when the working conditions are switched. In order to analyze the thermal stress of steam cooler tube sheet with high temperature load under harsh working conditions, the thermal-structural coupling analysis model of steam cooler tube sheet is constructed with finite element method. The results show that the stress concentration exists at the position connection between heat exchanger tube and cylinder. The maximum stress is located at the outermost heat exchanger tube with the peak stress of 320MPa. The heat exchanger tube layout alone cause higher stress. This situation should be avoided in the design of heat exchanger tube sheet. Furthermore, the strength and safety of the steam cooler tube sheet are evaluated with the stress linearization method. The steam cooler tube sheet design meets the safety requirements of structural strength under high temperature load.
Experimental Research on Rubber Compatibility of Drive Train oils used in Construction Machinery
Authors: An Haizhen , Liu Min , Zhen Penghou , Chen Li
Published: December 2021

The compatibility of oil and rubber in the drive train system of construction machinery plays an important role in the safe and reliable operation of the system. In order to investigate the rubber compatibility of drive train system oil of construction machinery, the changes of rubber sheet volume and hardness before and after immersion of standard fluororubber (FKM2) and hydrogenated nitrile rubber (HNBR1) with 9 kinds of drive train system oil were tested. The results show that FKM2 has good rubber compatibility with drive train oil, and HNBR1 is only compatible with some drive train oil; The volume change rate and hardness change range of FKM2 are smaller than those of HNBR1.