bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and Economic Prediction of Stock Index Based on Index Tracking and ARIMA Model
Authors: Zhang Xiaoduo , Zhai Rui , Gao Wen
Published: May 2021

Investors buy assets in the target index, if all, the cost is too high, generally not feasible. This paper carries on the stationarity test and the unit root test to the time series, establishes the ARIMA model of the stationary sequence obtained after the difference of the non-stationary sequence, determines the constant of the ARIMA model according to the ACF diagram and the PACF diagram. By analyzing the current exponential fluctuation, the time series model is used to predict the exponential fluctuation in the next year. Through the evaluation and analysis of the prediction results, reasonable investment suggestions and strategies can be obtained.
Stability Analysis and Error Estimation of Variable Coefficient Convection-Diffusion Equation: Generalized Numerical Fluxes
Authors: Liu Yuhang , Bi Hui
Published: May 2021

In this paper, we study the discontinuous Galerkin (DG) method with generalized numerical fluxes for one-dimensional variable coefficient convection-diffusion equation. For the convection term, we choose the upwind numerical flux, and for the diffusion term, we choose a special type of generalized numerical fluxes, thus we first show that the L
2 stability of the DG scheme. Then, by introducing the projection method, we are able to show k order optimal error estimates for the DG scheme. Finally, Numerical experiment is provided to verify the theoretical results.
A Summary on Two Types of Real Integrals Using the Residue Theorem
Authors: Liu Kaihang , Shao Liuyixin
Published: May 2021

It’s not easy, even impossible, to write anti-derivatives of most real functions in closed forms, which bring technical difficulty in using the fundamental theorem of calculus to compute real integrals. However, the residue theorem can be utilized to make calculations of some real integrals possible. In this survey, general methods of using the residue theorem are summarized to compute real integrals, and two specific real integrations are discussed.
Analytic Hierarchy Process Based Internship Selection
Authors: Wang Haojun , Jiang Jiayi , Sun Manrong , Xiao Yufeng
Published: May 2021

The summer internship is an important way for high school students to increase their social experience. However, it is difficult for high school students to choose a suitable internship due to their lack of social experience and lack of self-awareness. At the same time, the personality of each high school student is very different, and the requirements of different internships are also very different. In order to recommend suitable jobs for high school students, it established a recommendation model based on the analytic hierarchy process (AHP). Results show that the model has a very good effect.
Threshold of stochastic SIQR epidemic model with saturated incidence
Authors: Lai Jiawen
Published: May 2021

A stochastic SIQR epidemic model with saturated incidence was presented to control the spread of epidemic by taking antiviral prophylaxis and isolation measures. The threshold parameter is identified, which determines the extinction and persistence of the epidemic. The results are illustrated by computer simulations.
Modeling and Simulating on the Bandwidth and Capacity of Underwater Acoustic Channel
Authors: Guo Tieliang , Li Zhijun , Zhang Wenxiang , Li Binghuai
Published: May 2021

For underwater acoustic communication, the acoustic signals produce great attenuation in the propagation, and the complex environmental noise leads to the extremely limited bandwidth and capacity of the underwater acoustic channel. In this paper, the bandwidth and capacity of the channel are modeled and simulated under the condition that the transmitted power spectral density is constant. The theoretical analysis and simulation results show that the lower limit of the bandwidth of the underwater acoustic channel is determined by the noise and the upper limit is determined by the attenuation of the channel. Therefore, it is concluded that the narrow bandwidth of underwater acoustic channel is determined by attenuation and noise.
Control model of Furnace Temperature Curve
Authors: Wang Xu , Sun Pengju , Bai Huibin , Zhang Dongqing
Published: May 2021

This paper describes a measurement of the furnace temperature profile during reflow soldering by building a computational model from which we can get the furnace temperature curve under different conditions by increasing constraints with some critical parameters calibrated. Among these, the heat conduction and convection are considered as the most important heat transfer modes.
Disentanglement of Human Facial Features and the Inspection of Feature Extractor’s Quality Based on TL-GAN
Authors: Gao Yutong , He Shiwei , Wang Guanghan , Xu Peiyu
Published: May 2021

Recent research on the Generated Adversarial Network models has made great progress in the task of generating images on human demand. Among them, Transparent Latent-space GAN tries to solve the problem by analyzing the latent space and finding the feature axes inside it. This model views the problem from a novel perspective, and it is easy to be carried out. However, more thorough and detailed experiments have shown that the original method on axes disentanglement of the model has certain drawbacks, which may lead to ethical problems, meaning that the model may pick up some pre-existing prejudice of racial or gender discrimination. This paper puts forward a new training mode aiming at reducing the bias existing in the generated images and simultaneously managing the disentanglement. Also, a more thorough examination of the model was conducted and it is found that the architecture of the model may be generalized to some universal functions. Among them, the quality evaluation of the feature extractor is the most practical and useful one. This finding, in turn, may be helpful for distinguishing a more accurate, effective, and robust feature extractor, thus improving the performance of the TL-GAN model in the first place.
Pedestrian inertial navigation based on CNN-SVM gait recognition algorithm
Authors: Wu Xiaomeng , Zhao Liying , Guo Shuli , Zhang Lintong
Published: May 2021

Pedestrian inertial navigation technology based on inertial measurement unit (IMU) has been widely used in indoor and outdoor applications in recent years. But the IMU has a relatively low measurement accuracy that leads to error accumulation. Zero speed update algorithms (ZUPT) are often used to suppress the accumulation of errors. The key to the zero-speed update algorithm is to accurately find the stance phase in the pedestrian gait cycle. In this paper, an adaptive zero-speed detection algorithm based on CNN-SVM gait recognition is proposed for pedestrian positioning. First, the CNN-SVM algorithm is used to distinguish six gaits and find the optimal detection threshold according to different gaits. At the same time, it is proposed to use the zero-angle velocity update algorithm (ZARU) to correct the angle error, and to improve the accuracy of positioning by combining the information of zero-speed update and zero-angle velocity update through Kalman filter. Finally, the validity of the proposed algorithm is verified by experiments.
Algorithm for Solving Linear Fractional Programming
Authors: Xiao Yulin , Tian Xin
Published: May 2021

To solve the Linear Fractional Programming system, the Charnes-Cooper Transformation is used to split the original objective function to an equivalent, simplified linear programming system. To prove the congruence of two systems, the feasibility and optimality of the linear fractional program maximizes or minimizes a ratio of affine functions over a polyhedral set is proved. In the last part of the paper, a MATLAB function is used to design an algorithm which accepts the input of parameters of a fractional polyhedral set, and outputs the optimal solution.
Weighted SRGAN and Reconstruction Loss Analysis for Accurate Image Super Resolution
Authors: Cao Hangpu , Mi Sicheng
Published: May 2021

Super resolution (SR) image generation is to generate a high-resolution image from a given low-resolution image, which can be used in numerous vision tasks, such as small object detection and specific image processing. Generative adversarial network for super resolution (SRGAN) is the mainstream framework in SR task, which utilizes two reconstruction losses, including MSE loss and VGG loss. However, the influence of these losses on model learning is not examined. In this paper, the importance of MSE and VGG losses is analyzed. The loss function of traditional SRGAN is improved, and the weights of MSE and VGG losses are set manually. The weights range from 0 to 1, and the sampling interval is 0.1. Furthermore, a learnable parameter to dynamically adjust the two weights is proposed. Experiments on the datasets, including Set5, Set14, BAS100, and Urban100, show that our method is capable of generating much better images than SRGAN, with higher values of PSNR and SSIM. It is found that the MSE loss makes a greater contribution to learning the discriminative model and the VGG loss plays a supplementary role. Our WSRGAN can apply to most SRGAN-based methods to improve their accuracy.
Research and Practice on the Reform of Postgraduate Teaching Mode Guided by Cultivating Compound and Applied Talents------Taking mathematical statistics for example
Authors: Guo Yanli , Sun Qiang
Published: May 2021

This paper takes improving the teaching quality of graduate education as the guide. To improve graduates ’ ability of solving problems in life by using mathematical statistics and statistical software, the deficiencies of mathematical statistics in teaching process, and the causes of these deficiencies are analyzed in depth, in terms of teaching philosophy, teaching content, teaching methods, teaching means, and evaluation methods. Then some solutions to change this situation are discussed, as well as the problems that we need to be concerned in the process of reform.
Sinc Numerical Methods for Time Nonlocal Parabolic Equation
Authors: Yang Mei , Zhao Fengqun
Published: May 2021

In recent years, more and more researchers have paid attention to the study of non-local problems. The numerical method for initial-boundary value problems of time nonlocal parabolic equations is established in this paper. The time nonlocal operator is discretized by finite difference method, and spatial differential operators is discretized by Sinc-Galerkin method. Then fully discrete scheme (D-SD scheme) for solving one-dimensional time nonlocal parabolic equation is obtained. Numerical example shows the effectiveness and superiority of the scheme for solving non-local problems.
Research on Life Distribution of Hydraulic Seal O-ring Based on Covariate
Authors: Song Xincheng , Jie Yang , Wei Wang , Li Jiawei , Hao Wang , Yi Shaoqiang
Published: May 2021

Due to the lack of reliable big data, data-driven methods cannot be used to study the life distribution of hydraulic components. Facing the leakage failure of the hydraulic component is caused by the failure of the O-ring wear in hydraulic contact seal, According to the O-ring adhesive wear principle and Archard model, a method of fusing the internal leakage life test of hydraulic components with the simulation experiment based on the equivalent cross-sectional diameter of the O-ring is proposed. The leakage life test and simulation scheme of hydraulic cylinder designed by this method are used to solve the life distribution of piston hydraulic seal O-ring based on covariate. Finally, the life distribution response surface is established. It is proved that the method is feasible. The method provides a data channel for studying the reliability related problems of hydraulic components.
Pedestrian Navigation Method based on PDR/INS KF fusion and Height Update for Three-Dimensional Positioning
Authors: Meng Yujing , Zhao Liying , Guo Shuli , Zhang Lintong
Published: May 2021

Inertial navigation system (INS) and pedestrian dead reckoning (PDR) that use wearable MEMS inertial measurement units (IMUs) can track the location of a pedestrian on two-dimensional (2D) plane. This paper proposes a pedestrian navigation method based on INS/PDR Kalman filter (KF) fusion to calculate the trajectory of a pedestrian in indoor corridors, which can effectively suppress the heading drift. Besides, the height update algorithm is introduced based on the pressure output of a barometer to constrain the height divergence for three-dimensional (3D) positioning. The results of motion experiment show that the navigation accuracy of INS/PDR Kalman filter fusion method is significantly increased compared with the INS. The proposed height update algorithm have better correction effect on the problem of height divergence compared with ZUPT-aided inertial navigation algorithm.
A fire simulation method of urban light rail station hall based on building information model and pyrosim software
Authors: Ju Yanjie
Published: May 2021

Fire prevention is one of the key points of emergency management of urban light rail station. Based on the data interaction between building information model (BIM) and pyrosim software, this paper integrates BIM into pyrosim software, sets up the fire scenario of urban light rail station hall, analyzes the criterion index under fire condition, realizes the fire simulation of urban light rail station hall based on BIM, and obtains the fire simulation information and available safety information. Based on building information model, a fire simulation method of urban light rail station hall is established. Simulation verification shows that this method can give full play to the superiority of BIM technology.
Analysis and Optimization of Channel Capacity Based on Modified IFR Algorithm
Authors: Zhang Aoran , Zhang Jingyue , Zhou Shiqi
Published: May 2021

Massage passing can be communicated over different frequency channels at the same time. With the rapid development of the wireless system, more and more wireless applications have to compete for limited spectrum resources. These days, however, the spectrum vacancy is a serious issue that has aroused many studies. Therefore, how to make use of the resource properly has become a very significant problem to be mitigated. In this paper, we first study the frequency allocation by analyzing the capacity through using the Soft Frequency Reuse (SFR) system model applied in the Cellular Networks and building up a basic SFR model. Then we analyze the influence of the temperature by modifying the interference temperature model into a basic IFR model to find the impact on the environment. Finally, this result for IFR is extended to our SFR model to study the influence of the environment for SFR.

In this model, as our expectation, with the ratio of cell radius over the center radius grows, the network capacity increases. However, due to the spectrum’s shortage, this upward trend does not emerge significantly when the ratio is over 0.75. Considering factors related to temperature, even in the simplest environment, the influence of thermal noise cannot be ignored. Therefore, it is crucial to put temperature into account when simulating a more complex model in an environment similar to the real world.
Kinematic Analysis of Tensegrity Mechanisms Based on Improved Artificial Fish Swarm Algorithm with Variable Step Size
Authors: Lin Min , Yuan Xiaodong , Lei Hui , Ji Zhifei
Published: May 2021

To solve complex problems via the kinematics analysis of tensegrity parallel mechanism, a method based on the variable-step fish swarm algorithm was proposed, and the kinematics of the spherical joint-prismatic joint-spherical joint (3-SPS) tensegrity parallel mechanism was studied. The kinematics model of this mechanism was first constructed using the theory of minimum potential energy. Then, the variable-step fish swarm algorithm was operated to search the forward and inverse position solutions in the solving process. The simulation results showed that the variable-step fish swarm algorithm assured favorable convergence performance and search efficiency in solving the kinematics issue of the 3-SPS tensegrity parallel mechanism. Moreover, the algorithm can be applied to workspace solutions and the kinematics analysis of such a mechanism.
Subhyperbolic Rational Maps with Identical Julia set
Authors: Sun Xia , Ma Zhaoli
Published: May 2021

Permutable rational functions have identical Julia set. However, is the converse right? We have found a class of rational functions with degree two, they have identical Julia set but are not permutable. Moreover, they have hyperbolic periodic points only.
Optimal travel strategy model study
Authors: He Yiming , Li Yufan , Huang Dalin
Published: May 2021

In this paper, we propose an appropriate algorithm to determine the best strategy of an individual in the Through the Desert game, and give the generally applicable models for single-player and multi-player games under known and unknown weather conditions respectively. We integrate ant colony algorithm, branch-and-bound method and game theory to build and solve the optimization model.
The integration and application of BIM and GIS in modeling
Authors: Zhang Hang , Yuan Xitun , Yang Xiongfei , Han Qi , Wen Yongxiao
Published: May 2021

Refinement, intelligence, and standardization are the core requirements of today’s urban construction management. From the current situation, it is impossible to meet the needs of future urban construction and management by relying on a single technology. The integration of GIS and BIM provides new opportunities for urban construction management. GIS provides a basic framework for the construction and management of today’s cities, and BIM provides an accurate information model of a single building for urban construction management. The integration of GIS and BIM will bring new ideas and methods to city construction and management. A large number of high-precision BIM models provide detailed building information for city management and provide richer information for the construction of city 3D models. Although the fusion research of GIGIS and BIM has clear directions and urgent needs, the fusion research work of the two is still in the initial and exploratory stage.
Design of ship route through waterway based on dynamic programming
Authors: Zhengping Tang , Chao Ji , Xiaohai Wang
Published: May 2021

Aiming at the problem that the traditional route selection of ships is difficult to meet the requirements of precision and rapidness, based on the two-dimensional structure space of the grid sea area, a route planning model of ships passing through waterways is established, and a method to realize the optimal route based on the dynamic programming algorithm is presented. The simulation results show that the algorithm is an optimization algorithm for the local route planning of ships.
First-principles study on electronic structure and optical properties of N-Fe co-doped ZnO
Authors: Wei-rong Qiang , Xiao-mei Wang , Wei-qi Liu
Published: May 2021

In this paper, the electronic structure and photo-electric properties of N and Fe co-doped ZnO systems have been studied by using Density functional theory method. The results show that the formation energy of ZnO-N, ZnO-Fe, ZnO-N-Fe and ZnO-N-2Fe systems decreases in turn, the doping is easier to realize. Compared with the ZnO system, the activity of ZnO-Fe, ZnO-N-Fe and ZnO-N-2Fe systems increases in turn, the band gap of ZnO-N and ZnO-N-2Fe systems decreases, and the electron transition is easier in the doped system. The peak of the dielectric function shifts to the left, the absorption of the electron to the photon increases obviously, and the absorption spectrum appears red shift. It can be concluded that the electronic structure and optical properties of ZnO are greatly affected by the single and co-doping of N and Fe, which provides a theoretical basis for the further study.
Feasibility Study on Environmental Adaptability Test Platform of Rescue Drilling Rig
Authors: Dong Fan , Feifei Lu
Published: May 2021

The environmental adaptability test platform of rescue rig mainly studies the environmental adaptability of ground and underground emergency rescue rig, lifting and rescue cabin and other equipment. It provides verification means and standard basis for safety, and improves the reliability and adaptability of drilling rescue technology and equipment. It provides a platform for emergency rescue drill, actual operation and scenario simulation. After the completion of the platform, it has reached the international advanced level.
Research on Real-time Monitoring System of Motion Carrier Based on Satellite Positioning
Authors: Wendi Xie , Qijian Wang
Published: May 2021

The system uses CC2541 as the main control chip and mounts PCB antenna to realize Bluetooth wireless communication. GPRS wireless communication adopts SIM900A chip, which provides wireless link for users to upload data to the cloud. The satellite positioning module adopts ZOE-M8Q chip, supporting up to 12 satellite positioning; The cloud SERVER uses Windows Server 2012RC operating system to realize data monitoring and collection. Its based on satellite positioning data can be in the service of Android, IOS, and remote server monitoring system, and serving for the latitude and longitude, speed, time, mileage and other status information recording, storage of the carrier (unmanned vehicle, unmanned aerial vehicles (uavs), etc.). At the same time it can realize the solar energy conservation and emissions reduction, the cloud server storage and data processing through technologies such as GPRS and Bluetooth.
The fitting of three-body potential energy of solid argon
Authors: Zheng Xingrong , Su Li , Xie Kaiqiang , Chen Jingtong , Li Yujie
Published: May 2021

Based on atomic crystal configuration and the CCSD(T) calculation results, we obtain the fitting result of three-body potential energy of solid argon by fitting ab initio calculation results of this work, and make a comparison with the previous calculation results. Finally, we study and analyze three-body potential fitting results. It is concluded that the fitting curve is a simple and accurate tool to understand the high-pressure behaviors of solid argon, and the results are in very good agreement with ab initio calculation results, the recent experiment results at the present experimental pressure range.
Inhibition of Nitride Precipitation in a Fe-Cr-Mn-Mo-N High-Nitrogen Austenitic Stainless Steel through Grain Boundary Character Distribution Optimization
Authors: Shi F , Hu J , Wang L F , Guan X J , Liu CM , Li X W
Published: May 2021

The precipitation behavior of the second phase in Fe-18Cr-17Mn-2Mo-0.85N high nitrogen and nickel-free austenitic stainless steel after grain boundary character distribution (GBCD) optimization was investigated. The results show that the fraction of low Σ coincidence site lattice (CSL) boundaries increases from 47.9% for the solid solution treated specimen to 82.25% for the specimen cold-rolled by 5% and then annealed at 1423 K for 72 h (r5%-a1423 K/72 h). Compared with the solution treated sample, nitride precipitation is obviously restrained and the fraction of precipitates is the least in r5%-a1423 K/72 h sample with the highest proportion of SBs. The appearance of a high proportion of CSL boundaries with low energy inhibits the nitrides precipitation through GBCD optimization.
Application of autonomous navigation in robotics
Authors: Ju Wenshuai
Published: May 2021

In recent years, the robot industry has made great progress, and has been widely used in automobile manufacturing, machining, transportation agriculture, medical treatment, food and other aspects. The autonomous navigation is a key technology in the development of robot intelligence. Therefore, this paper extensively investigates the applications of autonomous navigation technology in the transfer robot, the medical robot and the agricultural robot. And we analyze and summarize the developments and applications of autonomous navigation related basic technologies, such as autonomous positioning technology, sports planning technology and 5 g communication technology. Finally, the future development prospect of robot technology and the autonomous navigation technology is given.
The Development of Color Display Technology
Authors: Xu Jingyi
Published: May 2021

Light-emitting devices play a vital role in people’s lives, and their extremely wide application has won the attention and research of many scientists for a long time. Light emitting diode based on semiconductor energy band and electro-optical conversion is the mainstream light-emitting devices. Furthermore, control the light by nano optical technology such as plasmon effect and the quantum dot is also attractive. This article reviews the latest research progress of the above three light-emitting devices and their principles and characteristics. Finally, we briefly summarized the advantages and disadvantages of these devices, as well as the possible development directions and potential applications of the next generation light-emitting devices.
Research on Lithium Battery Management System for Electric Trackless Rubber Tyred Vehicle in Coal Mine
Authors: Li Qiwei
Published: May 2021

This paper designs a kind of lithium battery management system for coal mine electric trackless rubber tyred vehicle based on chip STM32F105VCT7 as CPU. It focuses on the battery grouping mode, battery balancing strategy and the hardware and software design of the battery management system. The lithium battery management system uses LTC6811-1 chip to collect battery information, designs passive balance to maintain the battery, and uses RT thread real-time operating system to schedule the tasks in the lithium battery management system. Through the actual test application, the lithium battery management system designed in this paper can effectively monitor the battery voltage, temperature, current and other information, and complete the battery balance, charge and discharge control.
Modeling and Optimization of Security Robot Gait Balance Based on the Principle of Inverted Pendulum
Authors: Wang Junwen , Jiang Min
Published: May 2021

Robots have been increasingly applied to security protection. The modeling and optimal control of robot gait balance were discussed in this study based on a double inverted pendulum system. First, a trolley-type double inverted pendulum system was obtained by abstracting human gaits, a mathematical model corresponding to this system was constructed through the analytical dynamics method. Then a double inverted pendulum system controller was designed using the linear quadratic type control algorithm, a gain matrix K with the optimal performance was obtained by combining the experience piece-try method with regional dichotomy, and the effectiveness of modeling and optimization was demonstrated by comparing the typical value with optimized value in the end. This study is expected to provide a reference for enhancing the gait balance of security robots.
Simple Simulation of Ferrofluid by Using Moldy
Authors: Deng Xitian
Published: May 2021

Ferrofluid is a new material created in recent hundred years, which has both flowability like liquids and magnetism that was only found in solid materials before. It is an amazing material but is not known well by people. Although there are some simulations of ferrofluid, the author of this paper thinks it is too complicated for the beginners of this field. In order to help beginners to understand ferrofluid, the author creates a very simple model of ferrofluid and simulates it. This model is very simple so that beginners can understand it easily. The molecular dynamic program used by the author is moldy, which is also simple and widely used. Considering moldy does not contain magnetic force, the author uses electric force to replace it, because these two forces share a lot of similarities. After simulation, the author uses VMD (Visual Molecular Dynamics) to see its structure and movement in microscope. The author thinks that it will really help the beginners to understand ferrofluid and enter this field easier and inspire researchers to create new materials.
Well-aligned Polycaprolactone Fiber by Stable Jet Electrospinning
Authors: Guo Zhenzhao , Wu Zhe
Published: May 2021

In this work, polycaprolactone (PCL) fiber membrane with random, partially aligned and well-aligned morphology by conventional electrospinning, high speed drum electrospinning and stable jet electrospinning, respectively. By adjusting PCL polymer solution (solution viscosity and conductivity) and electrospinning parameter (voltage, temperature, humidity et al.), well-aligned PCL membrane with fibers arranged in one direction under SEM observation. The mechanical behaviour were also studied. The stable jet electrospinning offers a possibility of producing well-aligned fiber membranes for future potential applications.
Dry Spinning of Continuous Graphene Oxide/TPU Composite Fibers with Excellent Strength and Toughness
Authors: Feng Li , Liu Song , Luan Yunbo , Li Yongcun , Zhang Qi
Published: May 2021

Graphene fiber has broad application prospects in aerospace, biomedical and other fields because of its excellent mechanical properties. In this paper, graphene oxide (GO) and thermoplastic polyurethane (TPU) composite fibers have been prepared by two comparable methods including wet spinning and dry spinning. The fibers obtained by dry spinning show better strength and toughness compared with wet spinning. Further research results show that the dry spinning process can effectively control the internal microstructure of the fiber, improve the internal stress distribution and load transfer efficiency, then realize the optimization of its macro mechanical properties. This study will provide useful guidance for the optimization strategy of internal microstructure and the improvement of preparation process of graphene fiber.
Optimization of Shielding Electrode and Inner Shielding Structure for UHV Oil-gas Bushings with Improved Hybrid Algorithm Combining Particle Swarm Optimization and Back-Propagation Neural Network
Authors: Shiling Zhang
Published: May 2021

With the development of prototype for UHV oil-gas bushings, E-field distribution around bushing end and structure optimization for shielding electrode is an important issue to be studied. The basic principles and processes of hybrid algorithm combining particle swarm optimization and back-propagation neural network (PSO-BP algorithm) has been discussed in this paper. The optimization capability and accuracy of proposed algorithm has been verified with continuous explicit function. The structure optimization of shielding electrode has been conducted using PSO-BP algorithm. The study shows that PSO-BP algorithm can seek extreme point of testing function exactly, and jump over trap of local optimal solution; three-dimensional full model of bushing is needed in E-field distribution calculation; PSO-BP algorithm has found the best structure parameters of shielding electrode, with which more even E-field distribution can be obtained, and maximum electric strength can be reduced by 64.9%, moreover, the computing time is about 75.2% less than traditional PSO algorithm. The study results have been applied in bushing prototype manufacture which has passed through all testing experiments. The optimization method proposed in the paper can also be used in optimization design for other complex insulation structures.
Based on ADRC Strategy for Tracking Trajectory of Undamped Plants
Authors: Hu Weiwen , Zhang Shengguo , Xu Wenru , Yang Jiawei , Hou Hao
Published: May 2021

This paper mainly actualizes the precise trajectory tracking for the direct-drive servo system with undamped plant. Using the nominal model of the undamped object in this paper is to realize the precise control and obtain the better tracking effects by adopting the ADRC strategy which is introduced to avoid the overshoot causing by design of typical PID control law and improve the robustness of servo system. Simultaneously, it can also achieve the fast tracking and obtain the better convergence effects. Extensive simulations indicate that it practically validates the superiority of adopting the ADRC strategy to control these typical undamped plant. Both average placement tracking error and velocity tracking error for the sinusoidal waves and multi-step signal are converging to the value fluctuating around zero or gradually approaching to zero. This all-around control strategy to achieve the precise and fast trajectory tracing for the direct-drive servo system with undamped object is effective and feasible.
The interaction of rare earth cerium, neodymium, yttrium and phosphorus
Authors: Bai Zhiling , Qin Bingke
Published: May 2021

According to the Miedema model, the formation enthalpies of Nd, Y, Ce and P alloys were calculated; the entropies of NdP, YP and CeP were obtained using single gas ion entropy and crystal ion entropy. The results show that the thermodynamic properties of the compound between rare earth and P can be calculated. The free energy of formation of NdP and YP are both greater than zero. Therefore, [P]+[Nd]=NdP(s) and [P]+[Y]=YP(s) cannot be proceed spontaneously in the direction of the positive reaction. When the temperature is less than 964K, ΔGCeP
Θ is less than zero and [P]+[Ce]=CeP(s) reaction can be proceed spontaneously in the direction of generating CeP.
Research on selection of commercial industrial simulation software oriented to virtual commissioning
Authors: Sun Wenlin , Wu Jun , Xiao Guangchun , Jin Zhe
Published: May 2021

Virtual commissioning can find problems in the PLC program earlier and improve the efficiency of on-site commissioning. When constructing the FMS digital twin system with Beckhoff TwinCAT as the master control system for virtual commissioning of the production line, in order to select the most suitable modeling environment, this paper conducts research of predecessors based on commercial industrial simulation software. The four common commercial industrial simulation software with virtual commissioning function (Visual Components, Tecnomatix Process Simulate, Emulate3D, Flexsim) are introduced, analysed and compared from the two perspectives of software functions and features. Finally, it explains which commercial simulation software should be used for simulation and virtual commissioning in different scenarios.
Preparation and Performance Index Test of Continuous Glass Fiber Reinforced Filament- Polylactic Acid for 3D Printer
Authors: Wang Yesong , Lyu Changhuai , Zhang Qing , Li Wei , Liu Jiang
Published: May 2021

The “independent extrusion” 3D printer of Continuous Fiber Reinforced Thermoplastic Composites (CFRTPC) is gradually recognized by the market, but it cannot be widely used due to the limitations of printing materials. This paper focuses on the development of Continuous Glass Fiber Reinforced Filament- Polylactic Acid (CGFRF-PLA) for “independent extrusion” printing. The preparation device of Continuous Fiber Reinforced Filament (CFRF) was designed, and the effects of preparation process parameters such as temperature, speed and coupling agent on the performance index of CGFRF-PLA were studied by experiments, the best preparation process parameters were determined.
Monocular Visual Odometry based on joint unsupervised learning of depth and optical flow with geometric constraints
Authors: Meng X Y , Sun B Y
Published: May 2021

Inferring camera ego-motion from consecutive images is essential in visual odometry (VO). In this work, we present a jointly unsupervised learning system for monocular VO, consisting of single-view depth, two-view optical flow, and camera-motion estimation module. Our work mitigates the scale drift issue which can further result in a degraded performance in the long-sequence scene. We achieve this by incorporating standard epipolar geometry into the framework. Specifically, we extract correspondences over predicted optical flow and then recover ego-motion. Additionally, we obtain pseudo-ground-truth depth via triangulating 2D-2D pixel matches, which makes the depth scale is closely relevant to the pose. Experimentation on the KITTI driving dataset shows competitive performance compared to established methods.
Theoretical calculation model of insulation medium and eddy current heating under complex waveform of ±800kV convertor transformer RIP bushing used in valve side
Authors: Shiling Zhang
Published: May 2021

Electrical and thermal properties of the converter transformer valve side RIP DC bushing interact with each other, so electrical insulation failure in operation is directly related to the thermal properties. It is essential to conduct quantitative analysis on the power loss of UHV converter transformer dry-type bushing. The total power loss of bushing consists of two parts, eddy heat from current-carrying structures and joule heat from bushing core. The actual current and voltage waveform imposed on the bushing contain many high frequency components. In this paper, the theoretical calculation model of bushing core joule heat and eddy heat is obtained from structure of HV convertor transformer dry-type bushing. Then the temperature and frequency properties of epoxy impregnated paper used by dry-type bushing core are acquired by the experiments. Furthermore, based on the frequency domain FEM, the numerical calculation method for dry-type bushing power loss is proposed. In the end, the numerical results are used to analyze the factors that may lead to convertor transformer drytype bushing insulation failure in operation. The research result obtained in this paper is appropriate to compute thermal characteristic of bushing and is of directive significance to the operation, protection and accident analysis.
A LabVIEW based virtual instrument system for mid infrared laser spectroscopy measurements
Authors: Villanueva-López V. , Pacheco-Londoño L.C. , Haibach F.G. , Hernández-Rivera S.P.
Published: May 2021

The development of a virtual instrument (VI) interface to acquire spectroscopic measurements using a quantum cascade laser-based on LabVIEWTM is presented. The interface can enable mid-infrared laser spectroscopic data acquisition using a fast response mercury-cadmium-telluride (MCT) detector. The MCT is connected to an analog/digital converter card, and the data is displayed in a virtual high-speed oscilloscope. The VI processes the acquired data, displays the information, and saves it to a file through several operations using a “state machine” architecture. Transmission measurements of a polystyrene film were used to calibrate the system. They were compared to the National Institute of Standards and Technology-based FT-IR reference spectrum, showing excellent agreement. The system was tested with four different optical setups for IR Transmission, Diffuse Reflectance Infrared Spectroscopy, Reflection Absorption Infrared Spectroscopy, and Attenuated Total Reflection. The VI can be easily customized, allowing users to adapt it according to their specific laboratory needs.
Current distribution in magnetically confined 2DEG: semiclassical and quantum mechanical treatment
Authors: Németh Róbert , Kaufmann Zoltán , Cserti József
Published: May 2021

In the ballistic regime we study both semiclassically and quantum mechanically the electron’s dynamics in two-dimensional electron gas in the presence of an inhomogeneous magnetic field applied perpendicular to the plane. The magnetic field is constant inside four separate circular regions which are located at the four corners of a square of side length larger than the diameter of the circles, while outside the circles the magnetic field is zero. We carry out the stability analysis of the periodic orbits and for given initial conditions numerically calculate the two-dimensional invariant torus embedded in the four-dimensional phase space. Applying the Bohr–Sommerfeld and the Einstein–Brillouin–Keller semiclassical quantization methods we obtain the energy levels for different magnetic field strengths. We also perform exact quantum calculations solving numerically the discretized version of the Schrödinger equation. In our calculations, we consider only those bound states that are localized to the neighborhood of the four magnetic disks. We show that the semiclassical results are in good agreement with those found from our quantum calculations. Moreover, the current distribution and the phase of the different wave functions enable us to deduce the two quantum numbers n
1 and n
2 characterizing the energy levels in the semiclassical methods. Finally, we present two examples in which the quantum state shows a similar structure to the previous states, but these are special in the following sense. One of them is a scar state localized to the neighborhood of the periodic orbit while this orbit is already unstable. In the case of the other state, the current density is circulating in two rings in opposite directions. Thus, it is not consistent with the classical motion in the neighborhood of the periodic orbit.
Groundwater quality assessment with reference to some heavy metals toxicity and its probable remediation around Ballarpur area of Wardha valley coalfields, Maharashtra
Authors: Ganvir P S , Guhey R
Published: May 2021

Wardha valley coalfields are one of the major coal contributors in central India. The present study strives to assess the groundwater quality around Ballarpur area of Wardha Valley Coalfields concerning some heavy metals. 14 groundwater samples were taken for each pre-monsoon and post-monsoon season to assess Al, Cd, Cr, Cu, Fe, Pb, Ni, and Zn by AAS. Results disclosed that Cd, Fe, Pb and Ni were above the maximum permissible limit as per the Bureau of Indian Standards (2012). Fe, Zn, Cu and Al are the major percentage contributor in groundwater samples for both seasons. Shallow aquifer is more contaminated than deep. The PCA study has shown strong associations among a few heavy metals. The correlation coefficient study revealed that all heavy metals negatively correlate with pH values suggesting that contamination is favored in acidic water. Sampling locations and corresponding values imply mining activity as an influential cause for contamination. Hence, Acid Mine Drainage could cause a lower pH in the study area, augmenting heavy metals dissolution. To overcome, a flow system of anaerobic wetland and limestone drain could be a remedial method which will treat the mine discharge and mitigate the contamination.
Monitoring the Land Surface and water bodies temperature and its impact on surface water turbidity in Raipur, Chhattisgarh, India
Authors: Jaiswal Tanushri , Jhariya D C
Published: May 2021

Land use land cover change is the process taking place in different parts of the country throughout the world and is adversely affecting the environment and will continue to affect both directly and indirectly. It has an impact on the water resource in a negative way. Rapid urban growth as a major cause of land-use change is one of the biggest reasons for the rise in surface temperature, and LULC change is one of the major causes of concern throughout the world. In developing countries like India, rapid urbanization is greatly influencing surface temperature and water resources. Surface water bodies are greatly affected by the rapid urban growth, which is taking place in almost all parts throughout the country, especially in the central part of India which is having plain areas. Many studies have been conducted by using the thermal data in integration with the Remote Sensing (RS) and Geographic Information System (GIS) techniques for estimation of Land Surface Temperature(LST), and based on those studies, it can be concluded that changing land use has its direct impact on surface temperature as with increasing urbanization rise in LST has been observed. Therefore, the present study has been done to estimate the impacts of changing LULC on surface temperature and turbidity in surface water using the satellite-derived thermal data, and based on results obtained it can be concluded that areas covered with the settlement, open or barren land have a relatively higher temperature than those of the areas which have plants, and vegetation on and nearby it, also waterbodies with turbid areas are showing relatively higher temperature than that of clear surface water.
Photodegradation of aqueous eosin yellow dye by carbon-doped TiO2 photocatalyst
Authors: Ghime Damodhar , Mohapatra Titikshya , Verma Ananya , Banjare Virendra , Ghosh Prabir
Published: May 2021

In this study, a novel photocatalyst, carbon-doped TiO2 was prepared via a sol-gel technique with titanium (III) chloride as a precursor. The characterization of C-doped TiO2 was obtained by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and BET surface area analyses. The prepared catalyst’s photocatalytic activity was investigated using UV irradiation for the photo-oxidation of eosin yellow (EY) dye. The photocatalysis of EY dye was performed under various experimental parameters such as solution pH and oxidant dosage (H2O2). The prepared photocatalyst dosages were also taken separately to optimize process efficiency. About 77.43% of EY decolorization was obtained at an optimum pH of 3, and the performance was also observed by varying the oxidant concentration ranging from 5-10 mM. The % decolorization was higher for C-doped TiO2-200 photocatalyst (81.88%) compared to carbon-doped TiO2-400 photocatalyst (75.55%). It can be concluded that the carbon-doped TiO2, calcined at 200°C, can effectively decolorize EY dye in an aqueous medium.
Impact of Land-use and Land-cover Change on Groundwater Quality and Quantity in the Raipur, Chhattisgarh, India: A Remote Sensing and GIS approach
Authors: Mondal K C , Rathod K G , Joshi H M , Mandal H S , Khan Rubia , Rajendra Kushagra , Mawale Y K , Priya K , Jhariya D C
Published: May 2021

An attempt has been made to correlate groundwater quantity and quality concerning land use and land cover in the city, Raipur, Chhattisgarh, India. The land-use land-cover (LULC) is one of the dynamic processes of the urbanization method in a city or cities in a developing country. To assess the land use and land cover classes, we have used the multi-temporal remote sensing LANDSAT data of the year 2000 and 2018. There are ten LULC classes are identified, such as settlement, road, cultivation, industry, drainage, river, open land, vegetation, canal, and water bodies. The result shows that the LULC changes are mainly associated within the settlement and the cultivated area in the highest degree from 2000 to till date (2018). A comparison of LULC between the years 2000 and 2018 indicates that anthropogenic activities like settlement, road, and industrial areas have been expanded. The spatiotemporal variation of the water table and water quality parameters such as electrical conductivity (EC), Total Dissolved Solids (TDS), and Nitrate (NO3) between the year 2000 and 2018 have also been studied. The result shows that significant changes in the groundwater quantity and quality in the study area are due to anthropogenic activity.
Visualization of gold nanoparticles formation in DC plasma-liquid systems
Authors: LIU Zhaoyuan , CHEN Qiang , LIU Qinghuo , OSTRIKOV Kostya (Ken)
Published: May 2021

Dual argon plasmas ignited by one direct current power source are used to treat an aqueous solution of hydrogen tetrachloroaurate-(III) trihydrate (HAuCl4 · 3H2O) which is contained in an H-type electrochemical cell. The solution contained in one cell acts as a cathode, and in the other as an anode. Experiments are carried out to directly visualize the formation process of gold nanoparticles (AuNPs) in separated cells of the H-type electrochemical reactor. The results and analyzes suggest that hydrogen peroxide and hydrated electrons generated from the plasma-liquid interactions play the roles of reductants in the solutions, respectively. Hydrogen peroxide can be generated in the case of the liquid being a cathode or an anode, while most of hydrated electrons are formed in the case of the liquid being an anode. Therefore, the reduction of the AuCl4
− ions is mostly attributed to the hydrogen peroxide as the liquid acts as a cathode, while to the hydrogen peroxide and hydrated electrons as the liquid acts as an anode. Moreover, the pH value of the solution can be used to tune the formation processes and the final form of the AuNPs due to its mediation of reductants.