Journal of Computational Methods in Sciences and Engineering - Volume 21, issue 5

Authors: Shi, Zhengang | Fu, Wenjie | Sun, Chong | Zhang, Linhao | Li, Han | Wu, Chaofei

Article Type: Research Article

Abstract: The accuracy of optical current sensors in power systems will be affected by the interference of the external environment. Among them, temperature has a significant influence on the accuracy of optical current sensors, which is one of the main factors that restrict the practicality of optical current sensors. In this paper, the temperature field distribution of the optical current sensor with iron core is calculated by simulation. The influence of its structural parameters on the temperature field distribution is studied. It is compared with the temperature field distribution of the optical current sensor of the commonly used magnetic ring structure. …It is found that under the same current, the temperature of the magneto-optical material with the core optical current sensor is much lower than the optical current mutual inductance of the common magnetic ring structure. The geometric structure parameters of the optical current sensor with iron core have a great influence on its temperature field distribution. The temperature field distribution can be improved by optimizing the structure parameters, thereby improving the measurement accuracy. This article can provide a basis for the design optimization of optical current sensors. Show more

Keywords: Optical current sensor, iron core, temperature field calculation, structural parameters

DOI: 10.3233/JCM-204856

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1205-1214, 2021

Authors: Balsa, Carlos | Gama, Sílvio M.A.

Article Type: Research Article

Abstract: This work reports numerical explorations in advection of one passive tracer by point vortices living in the unbounded plane. The main objective is to find the energy-optimal displacement of one passive particle (point vortex with zero circulation) surrounded by N point vortices. The direct formulation of the corresponding control problems is presented. The restrictions are due to (i) the ordinary differential equations that govern the displacement of the passive particle around the point vortices, (ii) the available time T to go from the initial position z 0 to the final …destination z f , and (iii) the maximum absolute value u max that is imposed on the control variables. The latter consist in staircase controls, i.e., the control is written as a finite linear combination of characteristic functions on the real interval. The resulting optimization problems are solved numerically. The numerical results shows the existence nearly/quasi optimal control for the cases of N = 1 , N = 2 , N = 3 , and N = 4 vortices. Show more

Keywords: Point vortex, passive tracer, control problem, numerical optimization

DOI: 10.3233/JCM-204710

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1215-1229, 2021

Authors: Ma, Zhefei | Liang, Feiling | Xiao, Yong | Zhao, Yun | Xu, Di

Article Type: Research Article

Abstract: Aiming at the traditional topology identification based on steady-state operation, a topology identification method considering power system transient data is proposed. Firstly, the power system is dynamically modeled. Through theoretical derivation, the feature vectors that can reflect the topology information are extracted, and the topology identification problem is transformed into a sparse vector recovery problem. Based on compressive sensing theory, the orthogonal matching pursuit algorithm is adopted to solve the sparse recovery problem. Since the identification process is bidirectional, there may be some identification conflicts. For this consideration, an optimization strategy is introduced to improve the original algorithm. The influence …of each algorithm parameter on the topology identification performance is then studied. By considering the transient process, a large amount of effective identification data was obtained in only a few processes. Finally, a simulation test on the proposed algorithm on the IEEE standard 22-bus power distribution system is conducted. The results show that the improved algorithm has outperformed the traditional algorithm. Show more

Keywords: Power distribution network, topology reconstructure, sparse recovery, transient data

DOI: 10.3233/JCM-215005

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1231-1241, 2021

Authors: Luo, Chuan-Xi | Xiong, Chun-Long | Yu, Jiang-Miao | Li, Wei-Xiong | Huang, Zhi-Yong

Article Type: Research Article

Abstract: Because of its strong bearing capacity, good stability and easy control of construction technology, cement stabilized graded macadam was widely used in highway pavement structure. In order to solve its characteristics of easy cracking, relevant researchers have carried out systematic studies on it, but such studies did not involve the large volume and large scope of the structural layer, and only carried out research on the specimen and small scope. Based on engineering project, the influence of dust content and cement content on the cracking was studied by adjusting the parameters and paving the test section during the production process. …At the same time, the cracks in the project were counted, and the influences of exposure time, structural level, traffic load and construction level on the cracks in the cement stabilized graded macadam were analyzed. The relationship between crack spacing and exposure time is established, and through comparative analysis, it is found that construction level is the most important factor affecting crack spacing. Show more

Keywords: Cement stabilized graded macadam, structural layer, exposure time, traffic load

DOI: 10.3233/JCM-214891

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1243-1254, 2021

Authors: Qi, Qiaoyun

Article Type: Research Article

Abstract: Financial risk has a great influence on the development of enterprises, and the prediction of financial risk can help enterprises to treat risks early. In order to realize the prediction of enterprise financial risk, find the risk as early as possible and make a response as soon as possible, according to the principle of predictability and reliability, this study selected 15 financial indicators from aspects of debt repayment level, profit level, operation level, growth level, and cash level, then predicted the risk by the logistic regression model, and analyzed the risk of 36 pairs of enterprises. The results showed that …the model designed in this study had an accuracy rate of 91.67%, and the risk of a company was successfully predicted based on the financial situation of the company from 2018 to 2020, which verified the reliability of the method. Thus the model can effectively predict the financial risk of enterprises, and it can be further promoted and applied to ensure the long-term development of enterprises and establish a good market environment. Show more

Keywords: Logistic regression model, financial risk, financial crisis, financial prediction

DOI: 10.3233/JCM-214899

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1255-1261, 2021

Authors: Yu, Chunlei | Bao, Yingchao | Chen, Chao

Article Type: Research Article

Abstract: A finite element model (FEM) of the bracket arm of wrecker is developed and the mechanical behavior under six representative conditions is studied in this paper. Stress test experiment is carried out to validate the presented FEM. Comparison analyses show that results predicted from the FEM are in good agreement with those obtained from the test experiment. Moreover, the mechanical behavior analyses also give the danger working conditions for each component of the bracket arm. Based on the stress distributions under the danger working condition, structural improvement is conducted for the component which is prone to material failure. Mechanical behavior …analyses of the improved structures are also carried out in this paper. Numerical analysis results show that the maximum stresses of each improved component of the bracket arm are all reduced to close or below the allowable stress. This indicted that the load bearing capacities of each component are improved effectively and meet the requirements of engineering applications. Show more

Keywords: Bracket arm of wrecker, mechanical behavior, finite element analysis, stress test experiment, structural improvement

DOI: 10.3233/JCM-214906

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1263-1276, 2021

Authors: Qi, Xiangwei | Ge, Ren | Chen, Bingcai | Altenbek, Gulila

Article Type: Research Article

Abstract: Taking Uyghur character recognition as an example, this paper use a method of image segmentation which combines traditional methods with CNN, and transforms and implements the Uyghur character on intelligent devices. Firstly, after analyzing the application of several general segmentation methods, this paper finds some shortcomings but also some ideas for Uighur segmentation. Then, starting from the characteristics of Uyghur language, such as structure, word formation and input habits, the author studies the idea of Uyghur adhesive language segmentation from the perspective of language characteristics, puts forward the basic algorithm of Uyghur symbol segmentation, and applies the Uyghur character adhesion …segmentation based on minimum spanning tree and multi-queue primitive merging model to improve the segmentation efficiency. In addition, in order to solve the limitations of the traditional handwriting recognition framework of “preprocessing + feature extraction + classifier”, this paper puts forward a new solution of Uyghur handwriting recognition technology combining prior domain knowledge with CNN, constructs a Uyghur handwriting recognition model on the basis of CNN and random elastic deformation, and also improves the recognition rate of the system by combining domain knowledge with CNN. According to the experimental results, we can conclude that the mixed method proposed in this paper can effectively break the technical bottleneck of traditional methods, thus improving the efficiency of segmentation and recognition. Show more

Keywords: Image segmentation method, prior domain knowledge, CNN, character recognition, deep learning

DOI: 10.3233/JCM-214924

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1277-1291, 2021

Authors: Ren, Jie | Pu, Cuiping | Yu, An

Article Type: Research Article

Abstract: The reaction process of selective catalytic reduction (SCR) denitrification system is complex, which has the characteristics of large inertia, large delay, strong interference and uncertainty. Traditional PID control can’t achieve accurate control of ammonia injection. Based on linear active disturbance rejection control (LADRC), Smith predictor is used to eliminate the delay output variables before entering extended state observer. The nonlinear state error feedback control law of ADRC structure is designed by using sliding mode control law, which improves the fast response and stability of the system. To solve the problem that the selective catalytic reduction denitrification system is difficult to …achieve accurate modeling and large delay, Smith-SMC linear extended state observer (Smith-SMC-LESO) is designed. The simulation results of tracking characteristics, anti-jamming characteristics and robustness show that the set-point tracking performance and anti-jamming ability of Smith-LADRC and Smith-SMC-LESO are significantly improved. Show more

Keywords: ADRC, SMC, smith

DOI: 10.3233/JCM-214933

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1293-1304, 2021

Authors: Chen, Yanghou | Chen, Yangbo | Li, Jianwei

Article Type: Research Article

Abstract: Electrostatic adsorption dust removal can effectively improve the dust removal effect of inhalable particles. The grid layout in the flue gas affects the dust removal efficiency and channel pressure drop, and increases the power loss of the fan. In this paper, according to the velocity of flue gas and the concentration of particulate matter in flue gas, combined with the principle of electrostatic adsorption, a three-dimensional module including the main components of adsorption and dust removal was established. The distribution of pressure drop in the flue gas channel caused by the adsorption components with grid layout was simulated and analyzed, …which provided a reference for the reasonable layout of dust adsorption components. The simulation results show that the smaller the component diameter, the smaller the pressure difference caused by the same number of components, and the smaller the longitudinal spacing of components. Show more

Keywords: Electrostatic coalescence, flue gas dedusting, three-dimensional simulation, adsorption component

DOI: 10.3233/JCM-214952

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1305-1316, 2021

Authors: Chen, Guojin | Chen, Chang | Yuan, Yiming | Yue, Yishuai

Article Type: Research Article

Abstract: The internal combustion power equipment is a typical cyber-physical system (CPS). The traditional design method is to separate the information system from the physical system, and then to simulate and optimize separately every system. That can not achieve the best performance. Aiming at the internal combustion power equipment with multi-disciplinary deep integration, this paper establishes the multi-disciplinary model of the whole and key components based on Dymola software. There are mainly mechanical system, combustion system, cooling system, control system and other simulation models, including deceleration and fuel cut-off control unit modeling, start-stop control unit modeling and speed limit control unit …modeling. The performance of each model is simulated and analyzed. The mathematical models of engine characteristic curve and fuel supply rate curve are established through experimental study. Finally, taking the simulation model of automobile power system as an example, the simulation calculation and experimental verification are carried out, and the relationship among fuel supply rate, torque, speed and valve of internal combustion engine is obtained, as well as the cooling capacity of the cooling system is studied. The experimental results show that the maximum error between the simulation speed curve and the actual speed curve is within ± 2 km/h. The research results of this paper can provide theoretical basis for multidisciplinary modeling and simulation of internal combustion power equipment, and also provide technical support for performance analysis of internal combustion engine. Show more

Keywords: Internal combustion power equipment, multidisciplinary unification, modeling and simulation, cyber-physical system (CPS), fuel delivery rate, dynamic modeling laboratory (Dymola)

DOI: 10.3233/JCM-214961

Citation: Journal of Computational Methods in Sciences and Engineering, vol. 21, no. 5, pp. 1317-1337, 2021