bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly sensitive photonic crystal fiber chemical sensor for detecting carbon disulfide and bromoform in the THz regime
Authors: Nasif Mohammad Abrar
Published: July 2024

In this study, an innovative photonic crystal fiber (PCF) designed specifically for the detection of carbon disulfide and bromoform liquid chemicals within the THz frequency range was introduced. The PCF’s structural design was achieved using the Finite Element Method (FEM) and Perfectly Matched Layer (PML) boundary conditions within COMSOL Multiphysics, ensuring precision through appropriate numerical parameters. Six distinct configurations were developed, incorporating circular, square, rectangular slotted, benzene-shaped circular, and two elliptical core designs, as well as an eight-elliptical core design. The PCF models were constructed utilizing the dielectric material TOPAS for accurate simulation and analysis. Various crucial parameters of the proposed PCF were examined across a wide THz spectrum spanning from 0.2 to 1.2 THz. The PCF model exhibited a peak output at the operating frequency of 0.8 THz for the square-shaped core design, achieving a relative sensitivity of 96.891% for bromoform and 95.603% for carbon disulfide. Remarkably low material losses of 0.0081104 cm−1 for bromoform and 0.006703 cm−1 for carbon disulfide were observed, along with a core power fraction of 93.107% for bromoform and 94.263% for carbon disulfide. The effective area was determined to be 1.77 × 10−07
μm2 for bromoform and 1.70 × 10−07
μm2 for carbon disulfide, while the confinement loss measured 2.25 × 10−17 dB/cm for bromoform and 4.76 × 10−17 dB/cm for carbon disulfide. These superior attributes strongly suggest that this model will be crucial in applications like supercontinuum generation, sensing, and biomedical imaging.
Enhanced plasmonic absorption using MIM ring resonator structures for optical detector applications
Authors: Salahandish Mohammad , Ghahramani Bigbaghlou Reza , Nasiri Hassan , Pourziad Ali
Published: July 2024

This study delves into the design and analysis of plasmonic absorbers utilizing Metal-Insulator-Metal (MIM) ring resonator devices to achieve heightened optical absorption efficiency. Various ring resonator topologies, namely SRR-L and Ring-L, are investigated with the objective of amplifying absorption capabilities. Moreover, the examination extends to the influence of modifying the inner radius of the ring, resulting in discernibly diverse absorption levels. Through the integration of these ring resonators, absorption peaks are effectively brought into proximity, thereby yielding a broad-band absorption spectrum. Our discoveries underscore the promising potential of these devices as proficient optical detectors. The simulations were performed in three dimensions utilizing CST Microwave Studio.
Alternating spin splitting of electronic and magnon bands in two-dimensional altermagnetic materials
Authors: Wang 王 Qian 乾 , Wu 邬 Da-Wei 大为 , Guo 郭 Guang-Hua 光华 , Long 龙 Meng-Qiu 孟秋 , Wang 王 Yun-Peng 云鹏
Published: July 2024

Unconventional antiferromagnetism dubbed as altermagnetism was first discovered in rutile structured magnets, which is featured by spin splitting even without the spin–orbital coupling effect. This interesting phenomenon has been discovered in more altermagnetic materials. In this work, we explore two-dimensional altermagnetic materials by studying two series of two-dimensional magnets, including MF4 with M covering all 3d and 4d transition metal elements, as well as TS2 with T = V, Cr, Mn, Fe. Through the magnetic symmetry operation of RuF4 and MnS2, it is verified that breaking the time inversion is a necessary condition for spin splitting. Based on symmetry analysis and first-principles calculations, we find that the electronic bands and magnon dispersion experience alternating spin splitting along the same path. This work paves the way for exploring altermagnetism in two-dimensional materials.
Thermal pairing treatment within the path integral formalism
Authors: Fellah M. , Allal N.H. , Oudih M. R.
Published: July 2024

A method for the treatment of pairing correlations at finite temperature is proposed within the path integral formalism, based on the square root extraction of the pairing term in the Hamiltonian of the system. Gap equations and expressions for the pairing gap parameter Δ, energy E, and heat capacity C are established. The formalism is first tested using the Richardson model, which enables comparison with an exact solution. The results obtained using this formalism are also compared with the finite temperature BCS (FTBCS) results. An improvement over the FTBCS model is noted, especially at low temperatures. Indeed, the agreement between the Δ values of this study and the exact values is good at low temperatures. This leads to better agreement between the values of E and C of this model and the exact values than with the FTBCS values. However, a critical value of temperature remains. Subsequently, realistic cases are considered using single-particle energies of a deformed Woods-Saxon mean-field for the nuclei

Dy and

Yb. In the framework of the current approach, pairing effects persist beyond the FTBCS critical temperature. Moreover, at low temperatures, a good agreement between the model and semiexperimental values of the heat capacity is observed, and a clear improvement compared to the FTBCS method is noted. This is no more the case at higher temperatures.
A Remote Intelligent Check and Discharge Test System for Substation Battery Pack Based on Raspberry Pi
Authors: Zhang Liang , Gong Zemin , Lei Wei , Ni Pang
Published: July 2024

Regular check and discharge test of the battery pack is an effective means to ensure the normal state of the battery and timely detect outdated batteries. However, conventional manual check and discharge test methods are costly, cumbersome, and inefficient in maintenance. This article introduces a remote intelligent check and discharge test system for a substation battery pack based on Raspberry Pi. The system monitors the battery status in real-time, allowing operators to detect battery faults on time through the front-end management interface. At the same time, remote check and discharge tests can be carried out, greatly ensuring battery safety and solving the shortcomings of conventional manual methods.
A New Method for Traveling Wave Localization in Wide Area Power Grid Based on Trusted Zone Identification of Fault Lines
Authors: Wan Wanglong , Qin Zheng , Deng Minggao
Published: July 2024

Aiming at the problem of dead zones in fault localization of wide area power grids, which makes it difficult to improve localization accuracy, a new method based on the trusted zone of fault lines for precise localization of wide area traveling waves is proposed. The algorithm is based on the principle of dual terminal positioning, which determines the fault line in the network through the action status of the circuit breaker, and determines the calculation area of network positioning based on the fault line, obtaining a set of dual terminal positioning calculation paths based on the fault line; Then, calculate the reliable localization zone of the faulty line under all dual end localization calculation paths and use it to determine whether the localization result of the path is reliable. For calculation paths with unreliable results, identify the second traveling wave of the fault point for calculation; Finally, all credible positioning results obtained are linearly fitted to obtain the final accurate positioning result. Simulation and practical application results have shown that this algorithm does not require finding the shortest path for traveling wave transmission, and can effectively improve the accuracy of wide area traveling wave positioning. It has high reliability, strong adaptability, and a positioning error of less than 100m.
EAPTON: Event-based Antinoise Powerlines Tracking with ON/OFF Enhancement
Authors: Zhao Jiannan , Zhang Wenyuan , Wang Yang , Chen Shaonan , Zhou Xiang , Shuang Feng
Published: July 2024

Event-based powerlines detection and tracking is a thriving research topic with significance in autonomous powerlines inspection, especially for payload-limited UAVs. Currently, event-based line detection methods are developed to address line detection in dynamic scenes, including UAV-based powerlines tracking. However, due to the motion sensitivity of event cameras, it is challenging to eliminate false line detection caused by clustered events from a complex background. Taking inspiration from animals’ motion vision, we propose the EAPTON algorithm to address the vulnerable robustness against complex backgrounds. In our method, the brightness increments (ON events) and decrements (OFF events) are separately processed in parallel pathways, which is prevalent in animals’ motion vision. To increase selective sensibility to powerlines, we utilize the feature that twin-born ON and OFF events will simultaneously arise on the bilateral side of the powerlines. We verified our algorithm in a simulated powerlines inspection scenario with background noise, it outperforms the SOTA algorithm in robustness. Surprisingly, we found that the relative motion type between UAV and the target (e.g., powerlines) is strongly correlated with the statistical asymmetry of the ON/OFF events, which provides a modal of visual cues for motion estimation in other robotic tasks and may shed a light on the explanation of why ON/OFF neural mechanism exists in numerous animals motion vision systems.
Application of Data Security Protection in Smart Grid Based on Computer Electronic Technology
Authors: Liu Xiangguo , Du Huijun , Wang Zhonglong , Chen Jianfei , Peng Jia , Liu Yue
Published: July 2024

With the continuous improvement of the intelligence level of the State Grid, data security protection in power system automation has become an important challenge for the development of power enterprises. In order to solve this problem, this article is based on the research of power system structure, data types, and the current development status of security protection, combined with computer electronics technology, to conduct in-depth research on data security protection in power system automation, and establish a security protection model based on its theoretical foundation. In order to verify the effectiveness of the model, this paper tested it from three dimensions: data security protection degree, risk processing efficiency, and response time, and compared it with traditional security protection models. The test results show that under different test cases, the maximum protection degree of the data security protection model proposed in this article reaches 95.16%, and the average protection degree is about 91.88%. From the specific test results, it can be seen that the application of data security protection in power system automation based on computer electronic technology has strong operability.
Photovoltaic Power Generation Related Physical Quantity Mining Method Based On Historical Time Series Data Analysis
Authors: Wang Yin , Liao Siyang , Shen Nuoqing
Published: July 2024

The impact of distributed photovoltaic grid-connected on distribution network security, power quality and system stability cannot be ignored. In order to better cope with the uncertainty and output of new energy output and understand the characteristics of distributed new energy power output, it is necessary to predict photovoltaic power. The historical time series data of photovoltaic power is large in dimension and quantity. If the data output is not carried out, a large amount of redundant data will affect the accuracy of photovoltaic prediction. Therefore, this paper proposes a feature selection method based on MIC most mutual information coefficient, which filters out the most relevant data of photovoltaic power generation from the original feature variables, and then performs the feature dimension reduction method of linear discriminant analysis (LDA) to map the high-dimensional data to a lower dimension space. Finally, using the prediction simulation example, using the long and short time neural network (LSTM) prediction comparison, the feature dimension reduction method of MIC feature selection and LDA effectively improves the accuracy of photovoltaic power generation prediction.
Research and Simulation of Partial Discharge Phenomenon Sensing Technology for Substation Inspection Robots
Authors: Yu Hongxi , Xu Liang , Yang Lu , Li Dongqi , Xu Ke , Li Li
Published: July 2024

This paper thoroughly investigates the phenomenon of partial discharge in substations and proposes a set of simulation experimental apparatus to replicate various types of partial discharge defects in switchgear. By modifying the switchgear, incorporating models for different types of partial discharge, and equipping various standard partial discharge sensors, accurate simulations of phenomena such as point discharge, suspended discharge, gap discharge, and particle discharge are achieved. Through this system, the effectiveness of different detection methods, such as ultrasonic, high-frequency, and transient voltage methods, is validated for various defect models. Furthermore, utilizing an indoor inspection robot guide rail, the paper simulates the environment of partial discharge in substations, enabling the validation of the robot’s partial discharge detection performance and typical patterns under different conditions. This work is dedicated to providing situational awareness technology for partial discharge phenomenon detection for substation inspection robots, so that the inspection robot can detect various abnormal partial discharge phenomena in transformers or other substation equipment through micro sensors to promote the stable operation of the substation.
Distributed Dispatching Optimization based on Consistency Theory for Smart Grid
Authors: Lyu Pengpeng , Bu Qiangsheng , Guo Ye , Luo Fei
Published: July 2024

The energy management issue of a smart grid is the key to the efficient and stable operation of a smart grid. Due to the large number of distributed energy sources connected, the centralized dispatch method is no longer applicable, and the smart grid uses distributed algorithms for dispatch. In this paper, based on modeling and analysis of the smart grid dispatch problem, the distributed dispatch algorithm is designed by combining the consistency theory in multi-intelligent body systems. First, the distributed scheduling algorithm is designed under ideal communication conditions. Then, the correctness of the algorithm is verified in the MATLAB simulation platform under two conditions without considering the generator set output constraint and considering the generator set output constraint. The analysis of the study simulation results shows that the optimal solution of the scheduling problem is obtained when the marginal costs of the generation equipment converge consistently.
Transformer Fault Diagnosis Based on Intelligent Algorithm and Partial Discharge
Authors: Gao Lingtao , Zhang Anan , Lei Wei
Published: July 2024

As an important part of power transmission and transformation equipment and power systems, transformers’ operating conditions will have a direct impact on the stability and reliability of the power system. In view of the problems of high diagnosis cost and low accuracy of diagnosis results in existing fault diagnosis technology, this paper uses the pulse current method to detect the pulse signal generated by the discharge model based on the partial discharge experimental platform data, analyzes and studies the discharge characteristics of different discharge defects, and draws For the partial discharge phase distribution (PRPD) spectrum of each defect type, the statistical characteristic parameters characterizing the characteristics of the spectrum were extracted. The partial discharge statistical characteristics were used as classification feature quantities and input into three network models: RBF, GRNN, and PSO-GRNN. The results show that PSO-GRNN has a good recognition effect and is suitable for partial discharge type identification. It has important practical significance and application value for the all-round health management of power transformers.
Deep Learning-based Detection of Bird’s Nests on Power Transmission Towers
Authors: Huang Qing , Tian Meng , Chen Ziyang
Published: July 2024

The problem of birds building nests on high-altitude towers has posed a significant hidden danger to the safe operation of long-distance transmission lines. The current manual inspection method is inefficient and costly, while automatic inspection technology still faces challenges in accuracy and efficiency. This article mainly aims to propose a deep learning target detection algorithm YOLOV3 based on convolutional neural networks to monitor and retrieve bird damage faults on power towers. By constructing a large dataset of bird nests on power towers, deep learning training models are used to extract features of the detection targets, and the YOLOV3 algorithm is used to intelligentially identify images with bird damage faults. Experiments show that YOLOV3 can effectively detect bird nests on power towers.
Research on Coordinated Control and Hierarchical Partition Control Strategy of Distributed Generation in New Power System
Authors: An Zhihao , Lv Shaoshuai , Yin Ning , Wang Zongli
Published: July 2024

In recent years, the structure of urban power systems has become more complex and the power flow is more changeable, which seriously hinders the optimal scheduling of urban power systems. Therefore, it is necessary to realize the coordinated control of distributed generation, flexible load, and reactive power equipment globally and locally, improve the utilization rate of distributed generation, give full play to the source and load of electric vehicles and energy storage devices, and realize the optimal scheduling of urban power system. This paper proposes a multi-time scale distributed power coordinated control and hierarchical partition control model, which realizes the coordinated optimal control of the new power system for distributed power, load, and energy storage. The effectiveness of the model in this paper is verified by IEEE33 node simulation.
Quality Assessment Method for Insulator Sample Bank Based on Sampling Theory
Authors: Wei Jie , He Xing , Yi Zhihan , Li Xizhe , Song Rui , Chen Jian
Published: July 2024

Insulator strings are important components in power systems to support and isolate transmission lines. Due to long-term exposure to the natural environment, insulator strings are susceptible to damage, such as self-explosion, broken umbrella skirts, and galvanic corrosion, which is one of the most common failures. Once damaged, it can lead to widespread power outage, which affects people’s life and industrial production, so it is necessary to inspect and replace the damaged insulator strings regularly. This thesis proposes a quadratic sampling based approach to assess the quality of insulator string sample banks. Through simple random sampling, estimation and interval estimation of the sample pool, the pass rate and average number of labels of the original sample pool are initially assessed and compared with the usage requirements to decide whether to carry out a second sampling or not; the second sampling used SADS as an evaluation metric to assess the performance of the insulator string sample bank.
Calculation of the Structure and Reaction Potential Barrier of the Decomposition Products of SF6/N2 Mixed Gases
Authors: Niu Jien , Wang Yongqi , Liu Gang , Chen Honggang , Niu Huanhuan , Fan Xinhong , Zhang Zhengyuan , Zhao Rui
Published: July 2024

The greenhouse effect caused by SF6 gas in the power system cannot be ignored, and N2 has enormous industrial potential to replace pure SF6 by mixing with SF6 due to its advantages of low environmental pollution, low price, and stable chemical performance. This article combines density functional theory (DFT) and transition state theory (TST) to calculate the molecular structure and vibrational frequency information of various reactants, products, and transition states involved in SF6/N2 gas mixtures containing water and oxygen. The single point energy of each component is calculated using the CCSD (T)/cc pvtz theory level, and all reaction barrier energies are obtained. The calculated molecular structure and vibration frequency results are in good agreement with the experimental data of NIST, proving the reliability of the calculation method in this paper. The difficulty of the reaction can be determined by obtaining all the reaction barrier energies. It was found that SF5 molecules are unstable and prone to decomposition. SF4 is very important in the SF6/N2 reaction system, and further decomposition will produce a large number of stable by-products. The calculation method in this article helps to deeply understand the decomposition reaction mechanism of SF6/N2 mixed gas, and is of great significance for the research of decomposition experiments.
Comparative Study on Multiple Methods for Partial Discharge Detection of Gap Defect in Medium Voltage Switchgear
Authors: Hao Xiwei , Zhang Bei , Liu Zehui , Li Xinqiao , Shi Xinyue , Han Xutao
Published: July 2024

The medium voltage switchgear is a key equipment in the distribution network of the power system, which directly faces users. Once a fault occurs, it will cause huge economic losses and adverse social impacts. Partial discharge measurement is an important means to ensure the safe operation of switchgear. The physical quantities measured by different partial discharge detection methods are different, so the detection effects by different methods for the same defect are also different. This paper takes the common internal air gap defects of solid insulation in switchgear as the research object, and conducts partial discharge detection tests on real switchgear equipment. At the same time, radio frequency method, ultrasonic method, transient earth voltage (TEV) method, and pulse current method are used to detect and analyze the partial discharge generated by the defect. The results show that the radio frequency method, TEV method, and pulse current method have good detection sensitivity for air gap defects, but the ultrasonic method cannot detect this type of defect. Comparing the amplitudes of the three electrical signals, it can be found that the correlation between the TEV method and the pulse current method is relatively high, while the correlation between the radio frequency method and the two is relatively low. As the applied voltage increases, the amplitude of the radio frequency method changes linearly, which can more sensitively reflect the degree of defect change.
A Research on Internationalization of Technical Standards in the New Electric Power Industry Based on a Decision-making Aiding Model
Authors: Zhang Guoshu , Yi Tingting , Wu Liyuan , Zhang Lei
Published: July 2024

The internationalization of technical standards is an important part of the implementation of power grid standardization strategy. In this paper, a decision-making aiding model used for study on the internationalization path of grid standards is built based on the research on the standardization of foreign power grids and the analysis of the current situation of internationalization of Chinese power grid standards. Finally, based on the findings obtained from the verification with the model above, the implementation strategy for the internationalization of new electric power industry standards is developed to provide suggestions for the internationalization development of China’s new electric power industry standards.
A Low-carbon Dispatching Method for Cascade Hydropower via HVDC Flexible Delivery
Authors: Wang Yutong , Zhao Chenyong , Jia Heping
Published: July 2024

As a country rich in hydropower resources, the transmission of Southwest hydropower through HVDC system can achieve a large range of optimal allocation of resources, but the traditional HVDC transmission plan is often operated in high and low binary value, which is difficult to give full play to the flexibility of HVDC transmission, and increase the carbon emission and operation cost of the power system. In order to fully explore the flexibility of HVDC transmission mode to reduce system carbon emissions, this paper builds a mixed integer programming model based on the scenario of hydropower being sent to the receiving system through the HVDC system, taking into account such factors as low operating costs and carbon dioxide emissions of thermal power units at the receiving end, overload capacity of the HVDC system, and reactive power compensation cost of the HVDC system. A low carbon scheduling method for cascade hydropower HVDC flexible delivery system is proposed. Finally, taking the cross-regional transmission system of cascade hydropower station as an example, the model proposed in this paper is compared with the high-low binary transmission of traditional HVDC system. The results show that the dispatch mode proposed in this paper and the flexible operation of the HVDC system can promote the consumption of new energy, reduce the CO2 emissions of the system and achieve the dispatch goal of both low carbon and economic operation.
A Method for Calculating the Adjustable Capacity of Feeder Load Aggregators Considering the User’s Wishes
Authors: Ye Qiang , Chen Wuxiao , Jiang Zhijun , Cai Yuqing , Si Tianfang
Published: July 2024

With the deepening of China’s energy reform, large-scale renewable energy access has put forward higher requirements for the flexible adjustment ability of the power system. The research and application of mining flexible and adjustable resources on the user side to participate in the peak regulation and frequency regulation of the power grid have received extensive attention. With the gradual opening of the power market and the deepening of the reform of the power system, the feeder load aggregator has gradually become a new role in the power market, and the feeder load aggregator plays an important role in the centralized management of users, the optimization of distribution, and the realization of market-oriented transactions. However, the research on the participation of feeder loads in the auxiliary services of power grid peak regulation and frequency regulation is not perfect. In this context, this paper proposes a method for calculating the adjustable capacity of feeder load aggregators considering the wishes of users, in which the maximum voltage adjustable at the feeder and the change of the capacity of each user caused by the feeder voltage regulation are calculated by the feeder load aggregator through the power flow relationship, and finally the adjustable capacity declaration for the ancillary service market is completed.
Flow Field Analysis on Critical Feedback Information for UAV Autonomous High Speed Descent in Power Line Scenario
Authors: Sun Jiawei , Zhou Xiang , Zhao Jiannan , Shuang Feng
Published: July 2024

To improve the UAV efficiency in power line inspection, it must autonomously and rapidly descend to a specific height to complete the charging or landing task. This task requires the UAV to contain a stable control loop to face the specific airflow during autonomous and rapid descent: the vortex ring problem, and this specific airflow will reduce the UAV controllability. To implement the UAV autonomous high-speed descent, a control method must provide feedback information on the affected airflow and output a stable rotational speed. Hence, this paper designs a UAV autonomous high-speed descent control loop and proposes a variable rotor speed method to solve the feedback information in the control loop. This method reveals the relationship between the air movement caused by the rotor rotation and the controllability of the UAV high-speed descent. Therefore, with this method, the UAV control loop can obtain stable feedback on the air movement and achieve autonomous high-speed descent. To solve the UAV feedback information, we built the model to calculate the rotor speed in the autonomous high-speed descent UAV control loop and verified it by the CFD. The verification results showed that the model could reflect the actual fly condition. The proposed method solves the problem of UAV autonomous high-speed descent feedback information, improving the work efficiency of UAVs in power line inspection operations.
Analysis of the Influence of Distributed Photovoltaic Access on the Operation Quality of Asymmetry Distribution Network
Authors: Gu Taiyu , Tian Ye , Zhu Yidong , Wang Zhibo , Li Haifeng , Shang Lei
Published: July 2024

Distributed photovoltaic(PV) power generation, as a highly flexible renewable energy source, is currently developing rapidly and has been widely used. However, due to its uncertainty and randomness, large-scale distributed photovoltaic integration into the distribution network will change the network power flow distribution, which will have a greater impact on the operation quality of the distribution network operation. In order to study the influence of distributed PV access on the operation of asymmetry distribution network, this paper builds a three-phase power flow model of distributed photovoltaic access to distribution network. Based on the IEEE33 node three-phase calculation example data, the impact of distributed photovoltaic access location and capacity on a series of operation indicators such as voltage deviation, three-phase unbalance and network loss under asymmetry operation of the distribution network is studied. Finally, for the asymmetry distribution network operating condition, guidance suggestions for distributed photovoltaic access based on operation quality are given.
High Power Density Buck Boost DC/DC Converter Using SIC MOSFET
Authors: Rana Zuraiz , Meng Runquan , Ali Kashif , Haseeb Rashid
Published: July 2024

High power density is an advance in power electronics. Third generation wide-bandgap semiconductor devices (WBG SICs) offer significantly improved performance compared to standard silicon devices. SIC MOSFET is commonly used in power electronic equipment such as converters due to its low resistance, excellent thermal stability, and rapid switching speed. Increasing the switching frequency effectively reduces the circuit size. This article uses SIC MOSFET and STM32 single-chip MCU to design a high power density and higher frequency buck boost converter and establish a simulation model in LTspice. The driving circuit designed for SIC MOSFET is intended to maximize the converter’s reliability. Synchronous rectification applies to enhance the converter efficiency. Compared to other types of converters, the size of the converter is reduced, achieving the goals of lightweight and high power density of DC/DC converters.
Classification of Multi-Source Partial Discharge in GIS
Authors: Liang Liang , Yu Liangliang , Jiapaer Aizezijiang , Ji Changwei , Shang Wenming
Published: July 2024

Partial discharge (PD) analysis is an important method to identify electrical equipment faults. However, due to the influence of environmental electromagnetic interference and other equipment discharges in the power supply circuit during the on-site PD test, the collected PD signal is the combination of various PD and noise, which makes it challenging to identify the type or source of on-site partial discharge. A multi-source PD classification method based on the multiple threshold and K-means clustering algorithm is pro-posed to solve this problem. First, wavelet transform with an improved threshold is used to initially denoise the original signal. Then the multiple threshold method is used to filter the residual ripple between every two pulses. Finally, spectrum analysis is carried out for each pulse, and the maximum value of the spectrum is extracted as the feature quantity. Then, the K-means algorithm is used to classify the PD pulses, and the PRPD images of PD pulses in different frequency domains are obtained. The results show that the method adopted in this paper can denoise, extract and classify the PD signals collected on the site, and the PRPD diagram of PD pulse after classification is more obvious, which provides a basis for identifying the PD source on the site.
Research on the optimal design of roadway support for fully mechanized coal seam working face
Authors: Liang Qiuhui , Zhang Baoliang
Published: July 2024

For the optimal design of surrounding rock deformation and support in the shallow buried coal seam of large-scale fully mechanized mining face, this paper took the surrounding rock of the roadway as the research object, used theoretical calculation and numerical simulation to establish the mechanical model of the deformation of the surrounding rock structure, and proposed and analyzed the reasonable roadway support scheme of the shallow buried coal seam. The numerical simulation results showed that the top anchor rod with Φ18×2200 mm and the inter-row distance of 1100×1000 mm, the anchor cable with Φ15.24×6300 mm and the inter-row spacing of 2200×2000 mm, the upper part anchor of Φ16×2200 mm, and the C30 concrete with a thickness of 200 mm for laying the bottom plate are selected, which was certified as the optimal support scheme. In practical engineering applications, the deformation of surrounding rock has been effectively controlled, and the supporting effect of surrounding rock was obvious, which was of great significance to ensure the safe production of coal mines.
Theoretical and experimental research of filtration efficiency and resistance of multi-fiber air-filter materials
Authors: Yu Yanzi , Zhang Cheng , Zhang Jiuzheng , Wu Yaohua , Deng Rui , Wu Yu , Cai Jinming
Published: July 2024

The filtration efficiency and resistance during the process of fluid flowing through filter materials is significantly influenced by the characteristic of filter materials, especially for air-filter materials which generally have a multi-fiber composite structure. Therefore, it is important to pay attention to the filtration efficiency and resistance of multi-fiber filter materials. In this study, theoretical equations of filtration efficiency and resistance were proposed based on uniform and multi-fiber composite filter materials, and series of experimental verifications had been implemented. The results indicated that the experimental results verified the theoretical equations well, which may accelerate the research and development of new air-filter materials.
Optimized design of silicone oil torsional damper for diesel generator
Authors: Qiu Zexu , Chen Rongchuang , Wu Changbin , Liu Dingbang , Gan Xingang
Published: July 2024

Due to the high cylinder pressure and high-performance requirements, the silicone oil damper of an inline six-cylinder diesel generator needs to be optimized to reduce the crankshaft stress. The centralized mass method was used to simplify the crankshaft system. A multi-body dynamic model was established, and the crankshaft stress and torsional vibration amplitude were simulated. The results show that the excessive shear stress at generator crank pin 5 is due to the resonance between the first-order intrinsic frequency of the shaft system and the 3rd harmonic torsional vibration. The shear stress was analyzed for different damper thicknesses and stiffnesses, and it was found that the shear stress at crank pin 5 was minimized when the damper thickness was 60 mm and the torsional stiffness was 250,000 N·m/rad. The torsional amplitudes at different speeds and frequencies were measured in the bench test, and the results were consistent with the calculations. The designed silicone oil torsional damper meets the requirements of the 2000-hour bench test.
Dynamic analysis of a hydraulic motor lifting auxiliary beam of monorail crane
Authors: Liu Y L , Lu J L , Chu L L , Yu C L
Published: July 2024

Monorail crane that is an important class of auxiliary transportation equipment in coal mine. It works on a single hanging track fixed above the coal mine roadway to transport materials, machines, people, etc. Lifting auxiliary beam is the main part of the lifting beam which is used to complete the lifting and transport operations. In the application process, the lifting auxiliary beam is bore many types of loads such as discontinuous loading, frequent starting and braking etc. It complicates the dynamic performance that directly affects the safety and the lifting operation stability. By using finite element method, a dynamic model of the lifting auxiliary beam is established to study the variation laws of dynamic load, frequency, amplitude, etc. Furthermore, three loading conditions are defined in the model. They are static loading, slow loading and fast loading, considering the lifting operation time. The numerical simulation results show that the maximum displacement of the fast loading condition is 20% to 23% higher than that under the static loading condition. Moreover, under the fast loading condition, the largest displacement amplitude occurs in the middle part of the lifting auxiliary beam and it decreases gradually towards the ends.
Study on heat dissipation of torsional vibration damper for engine crankshaft
Authors: Chen Rongchuang , Qiu Zexu , Wu Changbin , Gan Xingang
Published: July 2024

High temperatures in torsional vibration dampers can cause silicone oil to fail, increasing crankshaft vibration and shortening component fatigue life. Accurate prediction of the damper temperature field is key to the manufacture of highly reliable torsional vibration dampers. This study establishes the relationship between temperature, torsional vibration amplitude, silicone oil viscosity, rotational speed, housing and inertia ring clearance, and heat generation power based on Comsol. A bench test was carried out on a 6-cylinder inline diesel engine. The simulated temperature profile matched the tested result in terms of trend and relative value, and the established model could accurately predict the temperature field of the engine crankshaft torsional vibration damper.
Surface properties of laser-woven magnesium alloys based on dot-matrix processing
Authors: Chen Jianli , Fan Yaohua , Wan Libo , Wu Weifeng
Published: July 2024

This paper investigates the enhancement of surface properties of magnesium alloys through infrared nanosecond laser processing with a focus on creating hydrophobic and wear-resistant surfaces. By manipulating dot-matrix microgroove sizes on the magnesium alloy surfaces, the research evaluates the influence on hydrophobicity and mechanical durability. The experimental results reveal that larger microgrooves contribute to increased hydrophobicity due to decreased liquid-solid contact, confirmed by static contact angle measurements which align with predictions from the Cassie-Baxter model. Mechanical durability tests, involving sandpaper abrasion, demonstrate that the surface integrity is maintained despite wear, attributed to the effective laser-texturing approach. The hydrophobic surfaces were achieved through a low-surface-energy modification using fluorosilanes, followed by a thermal treatment to ensure durability. The findings highlight the potential of this processing method in applications requiring robust, hydrophobic materials such as biomedical and engineering materials, offering a cost-effective and efficient solution for industry-scale problems. This work not only extends the understanding of surface engineering via laser texturing but also provides a novel approach for optimizing surface properties crucial for advanced material applications.
Numerical method determining the time-dependent position of a minority phase sphere in the Fe-Cu alloy droplet
Authors: Li Mei , Peng Yinli , Tian Lili , Liu Gang , Xie Fang
Published: July 2024

A numerical method was developed to track the dynamic positions of the L2 phase sphere inside the Fe-Cu alloy droplet. Firstly, the temperature field distribution within alloy droplet was calculated, and the variation in thermal gradient was analyzed. Secondly, the migration behavior of the sphere was analyzed based on Marangoni convection. Finally, the theoretical position of the 10 μm sphere was determined. The results demonstrated that there is a little difference in temperature between the center and the surface of the droplet, but its gradient is very different. Moreover, the maximum migration times for the L2 phase sphere were determined to be ~0.02 s, 0.07 s, and 0.14 s within 300μm, 600μm, and 900μm alloy droplets, respectively. In addition, it was also found that the same-sized spheres can reach the same relative position, i.e., 0.485R. This means the final position of the sphere within the different alloy droplets is independent of the droplet size.
Nanosecond laser-assisted fabrication of Ti6Al4V surfaces with gradient wettability and robust cross-linked microstructures
Authors: Chen Jianli , Fan Yaohua , Wan Libo , Wu Weifeng
Published: July 2024

Surfaces with gradient wettability outperform singular superhydrophobic surfaces in terms of self-cleaning efficiency, anti-contamination properties, and fluid manipulation. These attributes offer extensive application potential across various industrial and scientific domains. This study introduces and employs nanosecond pulsed laser ablation to create wettability gradient surfaces on Ti6Al4V alloys, featuring robust cross-linked frame microstructures. Experimental results demonstrate that by varying the ridge width (w), associated with the liquid-solid contact fraction, we can achieve varying wettability and mechanical durability in these cross-linked frame microstructures. Wettability tests indicate static contact angles ranging from 150.7° to 105.45°. Furthermore, the sandpaper linear abrasion test illustrates a decrease in material wear rate with an increase in w. Under similar test conditions, the proposed surfaces demonstrate superior mechanical durability compared to two other prevalent wettability surface structures. The proposed surfaces, efficiently and eco-friendly produced through nanosecond laser fabrication, hold tremendous potential for diverse applications.
Research on new distributed distribution network hidden fault remote automatic recovery technology
Authors: Liang Lingyu , Zhang Huanming , Zhao Xiangyu , Cao Shang , Huang Wenqi
Published: July 2024

To solve a series of chain reactions in which a fault in the distribution network triggers the shutdown of other components, a new distributed distribution network hidden fault remote automatic recovery technology research is proposed. The traditional chain fault model about line protection describes that when a fault occurs on one or some lines of the system, the line protection devices will operate with a certain probability, and the misoperation or inappropriate action of these line protection devices will lead to the expansion of the fault and ultimately form a wide range of power outages. This study quantitatively gives the interaction relationship between the components in the system. Firstly, the difference between the distribution network chained fault and the main network chained fault mechanism is analyzed; secondly, the topology of the distribution network is modeled; then, the fault transfer model of the distribution network and the chained fault model based on the line dynamics model are constructed based on this model; finally, the detailed distribution network chained fault algorithm process is given based on the proposed model.
Research on high-resolution capacitance detection circuit based on T-type network
Authors: Yin Zhenqing , Liu Hong , Hao Yuchao
Published: July 2024

The capacitance detection circuit is a key component of the servo circuit of the quartz flexible accelerometer, which needs to ensure high-precision capacitance detection. The small capacitance change of the quartz flexible accelerometer pendulum will be affected by the noise of each device in the servo loop. To solve this problem, we design a single carrier modulation and demodulation capacitance detection circuit based on a T-type network from the capacitance detection model of a quartz flexible accelerometer. We established a circuit noise model, quantitatively analyzed the noise of the entire capacitance detection circuit from the theoretical level, and obtained the equivalent capacitance noise of the circuit. The rationality and effectiveness of the high-precision capacitance detection circuit are verified by theoretical calculation. We also verify the accuracy of the theoretical calculation through simulation and obtain the signal-to-noise ratio of the circuit. Finally, we prove that the scheme is a high-precision capacitance detection scheme.
Parallel circuit currents in stator windings of a pumped storage power station
Authors: Du Shiyue , Li Hanlin , Shang Xin , Li Jiayao , Lang Yecun
Published: July 2024

In a pumped storage power station, equalization currents between the stator windings in phase are greater than the expected calculated value. Several 3D and 2D finite element calculations have been performed in this paper to evaluate the additional leakage reactance of the end winding for the different parallel paths. The calculation shows that the distribution of windings in the power plant leads to different leakage reactance values in the stator slots between parallel branches, resulting in a balanced current. The occurring equalization currents do not represent an issue for machine safety as they are not connected to machine asymmetries and do not lead to additional machine vibrations.
Research on SM-ADRC of BLDC motor based on GWO algorithm
Authors: Cheng Xuqian , Ni Xiaolong , Zhang Guochao
Published: July 2024

In recent years, the application of BLDC motors in all walks of life has become more and more extensive, and the precision requirements of the motor are also higher and higher. This paper proposes a method of ADRC and SMC, and the GWO algorithm is used to adjust parameters. Simulation graphics show that this method can enhance the control precision of BLDC motors.
Research on continuous commutation failure suppression strategy for multi-feed DC transmission system considering harmonic characteristic factors
Authors: Feng Qian , Zeng Ping , Zhou Desheng , Du Zhaoxin , Guo Shaodong , Yang Xiu
Published: July 2024

Regarding the sustained issues of commutation failures in the hybrid double-fed DC system encompassing Line Commutated Converter High Voltage Direct Current (LCC-HVDC) and Modular Multilevel Converter High Voltage Direct Current (MMC-HVDC, from the perspective of harmonics, the harmonics in the voltage waveform of the AC bus on the inverter side are analyzed. Besides, a commutation failure suppression strategy for the hybrid doubly-fed DC transmission system based on the minimum shutdown area is designed, in which the setting value of the shutdown angle of the harmonic is considered in the minimum shutdown area. The reactive power is obtained by attaching the setting value to the reactive power control link of MMC-HVDC, and the simulation analysis in PSCAD verifies that the strategy can make the MMC-HVDC output more reactive power during the fault in the weak AC system. Increasing the shut-off margin of the manifold reduces the potential for continuous commutation failures in LCC-HVDC.