bluuebunny/crossref_metadata_2025 huggingface dataset:
Orthogonal matching pursuit algorithm based on weighted cosine similarity for sound source localization
Authors: Xiao Yue , Wang Junyu , Yuan Lei
Published: August 2023

Compressive sensing overcomes the limitations of the Nyquist criteria and is one of the most widely used compressive sensing reconstruction algorithms. Orthogonal matching pursuit (OMP) algorithm is simple, in terms of hardware implementation, and has high computational efficiency. However, the OMP algorithm exhibits poor identification performance for low-frequency sound sources and results in large localization deviations when the mesh spacing of the focus plane is small. In this study, a novel atom selection criterion based on weighted cosine similarity was proposed to improve the OMP algorithm for sound source localization and characterization. This method replaces the original inner product criterion to measure the correlation between the column vectors of the sensing matrix and the residuals, which addresses the atom selection error caused by the high correlation between atoms. Numerical simulations and experimental results show that the proposed method has a stronger anti-noise interference capability and higher accuracy for sound source identification with fewer sampling points, particularly in low-frequency and low signal-to-noise ratio environments. Compared to other OMP algorithms, the proposed method improves the performance of the OMP algorithm in sound source localization and widens the sound frequency range. This study is valuable for achieving highly accurate sound source localization and reducing measurement costs in practical applications.
Fermions dynamic equation with Lorentz invariance violation and the corrected Hawking temperature in arbitrarily accelerating black hole*
Authors: Tan Xia , Zhang Jie , Li Ran , Yang Shu-Zheng
Published: August 2023

Containing Lorentz invariance violation (LIV), a new form of the fermions dynamic equation under the background of the curved space-time of the arbitrarily accelerating black hole, is studied. Firstly, we consider the new form of the fermions dynamic equation with arbitrary spin containing LIV in curved space-time, and research the fermions dynamic equation with spin

−

1

2

containing LIV. On this basis, according to the semi-classical theory and black hole quantum tunneling radiation theory, the quantum tunneling radiation of the arbitrarily accelerating Kinnersly black hole is modified correctly, and the corrected physical quantities such as black hole temperature and quantum tunneling rate are deeply discussed. The fermions dynamic equation with arbitrary spin in the arbitrarily accelerating black hole space-time and its solution are explained in detail. In order to further obtain the correction effect of the Planck scale, this article considers beyond the semi-classical theory and further obtains new expressions of the black hole temperature and tunneling radiation rate.
Spin–orbit torque in perpendicularly magnetized [Pt/Ni] multilayers
Authors: Cao 曹 Ying 颖 , Xie 谢 Zhicheng 志成 , Zhao 赵 Zhiyuan 治源 , Yang 杨 Yumin 雨民 , Lei 雷 Na 娜 , Miao 缪 Bingfeng 冰锋 , Wei 魏 Dahai 大海
Published: August 2023

The performance of spin–orbit torque (SOT) in heavy metal/ferromagnetic metal periodic multilayers has attracted widespread attention. In this paper, we have successfully fabricated a series of perpendicular magnetized [Pt(2–t)/Ni(t)]4 multilayers, and studied the SOT in the multilayers by varying the thickness of Ni layer t. The current induced magnetization switching was achieved with a critical current density of 1 × 107 A/cm2. The damping-like SOT efficiency ξ
DL was extracted from an extended harmonic Hall measurement. We demonstrated that the ξ
DL can be effectively modulated by t
Pt/t
Ni ratio of Pt and Ni in the multilayers. The SOT investigation about the [Pt/Ni]
N
multilayers might provide new material candidates for practical perpendicular SOT-MRAM devices.
Simulation of optical and electrical synaptic functions in MoS2/α-In2Se3 heterojunction memtransistors
Authors: Xiang 相 Tao 韬 , Chen 陈 Fengxiang 凤翔 , Li 李 Xiaoli 晓莉 , Wang 王 Xiaodong 小东 , Yan 闫 Yuling 誉玲 , Wang 汪 Lisheng 礼胜
Published: August 2023

Memtransistors combine memristors and field-effect transistors, which can introduce multi-port control and have significant applications for enriching storage methods. In this paper, multilayer α-In2Se3 and MoS2 were transferred to the substrate by the mechanical exfoliation method, then a heterojunction MoS2/α-In2Se3 memtransistor was prepared. Neural synaptic simulations were performed using electrical and optical pulses as input signals. Through measurements, such as excitatory/inhibitory post-synaptic current (EPSC/IPSC), long-term potentiation/depression (LTP/LTD), and paired-pulse facilitation/depression (PPF/PPD), it can be found that the fabricated device could simulate various functions of neural synapses well, and could work as an electronic synapse in artificial neural networks, proposing a possible solution for neuromorphic storage and computation.
Temperature relaxation and generalized Coulomb logarithm in two-temperature dense plasmas relevant to inertial confinement fusion implosions
Authors: Lin Chengliang , He Bin , Wu Yong , Zou Shiyang , Wang Jianguo
Published: August 2023

Detailed knowledge of energy exchange between electrons and ions is of fundamental importance for the description of temperature relaxation and also other nonequilibrium physics in Inertial Confinement Fusion (ICF). We present a theoretical model for the temperature relaxation rate and the related generalized Coulomb logarithm based on the Quantum Lenard–Balescu (QLB) kinetic equation, where no special cutoffs are needed to be introduced. To describe the collective modes characterizing the ionic acoustic waves, a single-pole approximation is introduced for the ionic dielectric response. The proposed model for the generalized Coulomb logarithm is examined over a wide range of plasma conditions for electron temperatures between 102 and 105 eV and electron densities between 1022 and

10

26

c
m

−
3

. The values of the generalized Coulomb logarithm are demonstrated to be in excellent agreement with the ones evaluated using the original QLB kinetic approach but with much less computational cost. Comparisons with molecular dynamics simulations and other theoretical approaches are presented. For further applications of our model, we present results for the recently measured experimental Coulomb logarithm. Compared to other widely applied models such as the Landau–Spitzer Coulomb logarithm, our model provides more consistent descriptions for the results of molecular dynamics simulations and also for the experimental outcomes. Our model for the generalized Coulomb logarithm is easy to calculate and can benefit efficient and reliable simulations for the ICF implosions.
Performances of Multi-Configuration Piezoelectric Connection with AC-DC Converter in Low Frequency Energy Harvesting System
Authors: Abidin Nik Ahmad Kamil Zainal , Nayan Norkharziana Mohd , Azizan M M , Jamel Nursabirah , Ali Azuwa , Azli N. A. , Nordin N. M.
Published: August 2023

Harvesting energy by capturing vibration from low frequency energy have been explored extensively. In essence, a single piezoelectric transducer or an array of piezoelectric connections are used to convert kinetic energy into electrical energy in order to produce low frequency energy. In this paper, multi-configuration array piezoelectric connections are used to investigate the performances of different converter circuit types in low energy harvesting applications. This research utilized three pieces of circular piezoelectric sensor to test the combinations of array connection. There are four options for the piezoelectric sensor configuration: parallel (P), series (S), parallel-series (PS), and series-parallel (SP) while the full wave bridge rectifier (FWBR), parallel voltage multiplier (PVM), and parallel Synchronized Switch Harvesting on Inductor (P-SSHI) converter circuit are chosen AC-DC converter circuits. The system is assessed using a variety of load configurations, including 10 kΩ and 1 MΩ with a 3 Hz input frequency. In order to produce the highest possible output of collected power, the observation focuses on identifying the ideal combination of array piezoelectric connections with AC-DC converter. The result shows that 3-Parallel (3P) piezoelectric connection obtained a higher power output among the other types of array piezoelectric which was 5.97μW. The FWBR circuit generated the highest output power with 2.42μW for a combination of piezoelectric sensors array of 3P connection with the AC-DC converter.
Design A Giant Battery Energy Storage for Port Application
Authors: Osman IS , Ahamad N.B , Mat Suboh S. , Isa NM , Othman M.
Published: August 2023

Most of the seaports are toward green technology with a focus on renewable energy and energy storage to reduce emissions that will affect the environment and health of people living near the place. This is due to the main port’s activity as a hub for connecting to other places and also trade. However, the load consumption at the seaport is high at an average of around 1,581 kW per day depending on the application. This paper presents the method to design a giant battery for energy storage to reduce diesel and grid supply used. Therefore, to purpose this the mathematical model was developed by using the generic battery of lithium-ion type based on the Shepherd model. Generic battery models are available in MATLAB/Simulink library. In particular, this study investigates how voltage and state of charge can be determined with sufficient accuracy for a given load profile. Thus, the giant battery simulation model was developed based on the mathematical model. Finally, the giant battery model is included in MATLAB/Simulink simulation, and the procedure of determining the model parameters is discussed in detail. The results show that the model can accurately represent the dynamic behavior of the battery and is assumed to operate at a maximum SOC of 80%, with a total capacity is 126500 Ah. 20% to 80% of SOC is the safe limit for the battery to operate. Besides that, the return on investment (ROI) cost also considers in this paper.
Assessment of wind power potential in the North region of Malaysia, Chuping Perlis
Authors: Thiraphorn B L , Leow W Z , Safwati I , Irwan Y M , Irwanto M , Tan X.J. , Ananda-Rao K
Published: August 2023

The wind turbines is a main device that convert the kinetic energy from blades to electrical energy. Before installing wind turbines, the Weibull probability distribution must be calculated to determine the certain wind speed probability. Many problems will come if there no analysis the characteristics of wind in selected location, such as wind speed that not suitable for building wind farm to supply the population in that area. Shape and scale factors, which be controlled in a variety of ways, influence the Weibull distribution. Many studies have looked into which of the various Weibull parameter estimation methods is the most dependable. However, because the results of these investigations were inconsistent, research into more trustworthy Weibull parameter estimation methods is still ongoing. An analysis of data collected Chuping, Perlis for two years was conducted in this study (from 2018 to 2019). By using statistical analysis to evaluate the Weibull distribution method, this study used three methods to compared the Weibull parameters and identified the most reliable and effective method to obtain the Weibull probability distribution by using a three approach that compares the variances of RMSE, MSE and R2, which provides comprehensive insight into level error and volatility. Modified maximum likelihood method, graphical method, and power density method are the three methods used in this study. Therefore, the graphical method has the best accuracy in the wind speed distribution prediction, several methods such as the modified maximum likelihood method, and the power density method have the worst prediction of the wind speed distribution based on all the statistical method variances for this region.
Direct Current Corona Characteristics of Innovative Portable High Voltage dc to dc Booster Device in Corona Charging Setup
Authors: Nath Rameshwar , Tiwari Badri Vishal , Tiwari Anil , Ghodke Nand Kishor
Published: August 2023

In the present work an experimental investigation has been carried out to study the corona characteristics of a portable high voltage dc to dc booster device proposed and used by us for the first time as an innovation in corona charging of electrets. The experiments were conducted in a point-to-plane system to measure the corona current I as a function of applied corona voltage V and inter-electrode separation. Obtained results have been analyzed and discussed successfully in the light of cited works and show that both positive and negative corona produced by this device is consistent with the Townsend Relation adapted for point-to-plane geometry. This device is suitable and effective in applications where the local corona is required.
Reverse Sensing Kinetics investigation with STM of Deep-UV triggered TiO2/WO3 NCs for Isoprene detection
Authors: Akshaya M V , Suja K J , Basu Palash Kumar
Published: August 2023

Traditional diagnostic technologies in the health sector are either bulky or expensive and invasive; hence, the breath analyzer era emerged, wherein it can be a single sensor for a single illness diagnosis or a multi-sensor array to diagnose a single disease with numerous biomarkers. Isoprene, commonly known as a biomarker for various diseases, mainly for oxidative stress/cholesterol abnormalities, is targeted in this study. A drop-casted layer of microwave-treated Titanium dioxide/Tungsten oxide (TiO
2/WO
3) nanocomposites (NCs) optically activated in the deep UV (λ-300nm) range is employed for the detection of Isoprene. An optimised moderately doped TiO
2/WO
3 NCs calibrated under 20 to 80 ppb of isoprene is considered from our previous work and thoroughly investigated for its sensing pattern discrepancy under optical activation. Our study aims to comprehend the reverse sensing pattern observed during optical activation of the sensing layer utilizing a precision scanning tunnelling microscope (STM) integrated with a deep-UV LED of λ-300nm. STM experiments confirm that the observed reverse sensing pattern, which contradicts the normal mode, is driven by an excess photogenerated surface n-type carrier concentration of 8.785 × 1015
cm
−3.
Design and Analysis of Sphere Yagi antenna at 915 MHz Band for LoRaWAN Application
Authors: Haque Ashraful , Azman Zakariya M , Mohamad Hisham , Khir M. H. Md , Rahman Afzalur , Saha Dipon , Aiman Muazzam M , Hussin Eryana Eiyda , Nor M Faizairi M , Beddelee Aizat Akmal Bin A. mohamad
Published: August 2023

Using a frequency of 915 MHz as an operating point, this project has analyzed and refined the design of a Sphere Yagi antenna. In CST, we have begun the research phase and created a preliminary design for an antenna. The simulation results have been analyzed, and then fabrication, testing, and measurement have been carried out. To begin the manufacturing process, a single-sided copper board is cut into sphere shapes, with the length of each plate varying depending on the size of the sphere. Drilling machines are then used to create a hole in each of the plates. As a result, everything is coming together nicely. In addition, both indoor and outdoor settings have been used for testing and experiments. Therefore, the antenna design works well in 915 MHz frequency, but the signal weakens when it travels more than 100 meters away. An improved antenna transmitter’s power output can fix this. This project can be extended to cover the 2.4 GHz and 5 GHz frequencies. So, the antenna layout can be employed to improve the wireless connection of communication devices that need extensive range.
DSP based Hardware-in-the-Loop (HIL) Simulation for GCPV-based DSTATCOM using Frequency Domain Controller
Authors: Sobri N F A , Baharudin N H , Mansur T M N T , Syahril M , Ali R , Ananda-Rao K , Suboh S M , Abdullah A M
Published: August 2023

This study presents a comprehensive simulation of digital control applications for a grid-connected photovoltaic (GCPV) system using a Hardware-in-the-Loop (HIL) simulation approach that incorporates a Digital Signal Processor (DSP). The simulation is carried out using the MATLAB Simulink block set and employs a frequency domain controller as the control algorithm. The simulation inputs, which consist of voltage and current sensor readings, are processed by an ADC idealizer block that produces output based on a real-time DSP-based HIL system. The output is then utilized to generate a pulse width modulation (PWM) signal, which drives the voltage source inverter (VSI). The simulation’s primary objective is to demonstrate the simplicity and efficacy of the proposed frequency domain controller design for the GCPV-based DSTATCOM system. The simulation results validate the performance of the controller under various operating conditions, including steady-state, unbalanced loads, variable solar insolation, and day-to-night transitions.
Modelling and analysis of electrical performance outdoor glass insulator under various services and lightning impulse
Authors: Su TY , Yaakob SB , Ariffen AM
Published: August 2023

This paper is focus on modelling of glass type insulator with voltage rating of 275 kV. The glass insulators are still widely served in overhead transmission line because of its high dielectric strength capability. However, their outdoor application has resulted in the exposure to the various service conditions such as weather, pollution and lightning conditions. Further, the inclination effect of the insulator under the nominal voltage and lightning impulse is modelling through Finite Elementary Method (FEM). Then, the model of glass insulator is constructed in three different inclination angles by using the Ansys Maxwell 3D for simulation purpose. The results show the inclined insulator due to the wind load effect has the lowest breakdown voltage at most 53.33% compared with the vertical insulator. Under the outdoor environment factors such as humid, wet and contamination, the localized electric field and current density had increased significantly. Consequently, this situation may cause the power losses, localized heating effect also reduces the electrical performance of the insulators.
Dual Outputs Switch Mode Power Supply (DOSMPS) Utilizing Forward Converter Topology
Authors: Fauzi F , Udom U , Zaidi M E , Manaf N A A
Published: August 2023

Experimental works of dual, 5 volt DC outputs switch mode power supply (DOSMPS) is presented in this paper. To design, construct and evaluate the DOSMPS using forward converter topology are the objectives of this article. In this work, a 556 timer was picked as the pulse width modulator. The 556 timer was picked because it is widely used, cheap and capable of producing stable dual pulse width modulations. Since, this work targeted dual DC outputs, two forward converter circuits were built. However, switching frequencies at two transistors were controlled by only one 556 timer. The complete circuit of the DOSMPS consist of full bridge rectifier, smoothing capacitor, two high frequency transformers and two forward converter circuits. At the first stage of this work, the DOSMPS circuit was designed using Proteus software. Later, the complete DOSMPS circuit was constructed on two breadbroads after all of the electronic components and devices were available. Important parameters such as the input and output voltages and duty cycles were measured using digital oscilloscope and multimeter. Results from these measurements have shown that the designed circuit can convert single-phase 24 Vrms 50 Hz AC voltage input into dual and stable 5±0.1 V DC outputs. Also from this work, it was observed that, pulsed DC voltages with peak value of 2 V and frequency less than 20 kHz are sufficient in controlling the switching frequencies of both BJT transistors. This allows the regulation of the output voltage within the desired range. Analysis carried out after the measurements has shown close correlation between the theoretical and experimental results, where the calculated and measured switching frequencies had only deviated by 1.1%.
Lightning Impulse Voltage Stresses In Underground Cables
Authors: Laili M S , Fen C M L , Isa M , Arshad SNM , Zakaria Z N
Published: August 2023

Underground power cables are crucial for transmission and distribution. Lightning can stress their insulation, but not directly. So, impulse cable testing is studied. This research examines the cable’s transient response to standard and non-standard lightning impulse voltage waveforms. MATLAB Simulink was used to model a 132 kV wire with standard and non-standard impulse voltages. The IEC60060-1(2010) lightning impulse test uses a conventional waveform impulse voltage with a front time and a tail time of 1.2/50μs half value, while the non-standard test uses a front time and a tail time of 0.8/12s half value. Non-standard impulse waveforms are more accurate than standard waveforms. The impulse test voltage is four to five times the underground cable’s operational voltage and must withstand five applications without damage. Standard and non-standard impulse waveforms are injected with 132 kV and 550 kV to evaluate insulation failure or damage. Standard lightning and non-standard impulse voltage waveforms do not cause insulation failure or damage. When 132 kV and 550 kV are introduced into the normal and non-standard lightning impulse waveforms, the overshoot voltage increases. The peak voltage of a non-standard 550 kV impulse voltage waveform exceeds the IEC impulse withstand voltage. The finding shows that non-standard impulse voltage waves create increased cable voltage stress.
Control Method of Seamless Transfer from Grid-Connected Mode to Isolated Mode for Microgrid Demonstration
Authors: Wu MeiRong , Xue Fei , Ren Yong
Published: August 2023

It’s easy to cause transient oscillation problems when the microgrid transfers from the grid-connected mode to the isolated mode, so a control method of seamless transfers from the grid-connected mode to the isolated mode for microgrid demonstration is proposed. The switching control strategy of the outer loop controller for the master unit(s) makes the reference value of the current inner-loop controller the same when the microgrid transfers to isolated mode. While the switching control strategy of phase locked loop (PLL) uses an ample-hold assign the output angle of grid-connected PLL to the oscillator adopted by the microgrid in isolated mode at the switching moment. Finally, the sub-regional control strategy uses different control strategies to reserve more spinning capacity for the master unit(s) which divides the power balance into 3 regions. At last, the simulation is verified that the proposed control method not only realizes the seamless transfer from grid-connected operation to islanded operation for the microgrid but also improves the anti-disturbance ability of the microgrid in isolated mode.
Simulation of Spent Fuel Assembly Transport Vertical Drop Based on LS-DYNA
Authors: Wang Xiaoqi , Fan Youchen , Chi Qidong , Wang Hehui
Published: August 2023

The finite element technology is used to carry out the drop simulation and safety assessment of the spent fuel assembly and its transport cask. In view of the problem of how to reasonably simplify the finite element model, a more reasonable and accurate multistage simplified model is proposed for the spent fuel assemblies packed densely in the transport cask, which needs to be analyzed synchronously when dropping. First, the “key” spent fuel assembly is retained, and the “unimportant” assembly is simplified as a cylindrical entity. Based on this, the structure will continue to be simplified and a 1/4 near-earth model containing all characteristics will be established. Then, the LS-DYNA software is used for explicit dynamic analysis of vertical drop conditions. It is concluded that the failure risk of the spacers is the greatest. Therefore, the purpose of this paper is to propose a multistage simplified method for spent fuel assembly and its transport cask, which can provide a reference for the structural integrity analysis of the spent fuel assembly transport drop conditions.
Stiffness Analysis of High Contact Ratio Spur Gear with Asymmetric Teeth
Authors: Liang Xiao , Tang Xin , Li Yingjun , Shen Rui , Li Fajia , Wu Ziheng
Published: August 2023

The demands of high carrying capacity and low vibration of gear transmission systems in aviation, aerospace, and other areas are addressed by high contact ratio gears with asymmetric teeth, which have a wide range of potential applications. The Weber energy technique is utilized to determine the stiffness of high contact ratio spur gears with asymmetric teeth, and the effect law of the stiffness parameters is researched, due to the paucity of study on these gears. The influence of the drive side addendum factor, modulus, and pressure angle on the stiffness of asymmetric high contact ratio spur gears is investigated. The deformation of the gear will be exacerbated by an increase in the addendum factor, and the comprehensive stiffness of the gear will grow as more gear pairs participate in the meshing. The rigidity of gears may be greatly increased without ignoring modulus if the driving side pressure angle is properly increased.
Precision Variable-rate Control System for Mini-UAV-based Pesticide Application
Authors: Zhang Zhihong , Yuan Shuo , Lai Qinghui , Zeng Ronghao , Zhang Jingkun , Shen Siyu
Published: August 2023

Mechanized and efficient pesticide application is an effective measure to prevent crop diseases, control pests, and ensure stable yield. For crops in greenhouses, due to the complex operating environment, the traditional mechanical spraying method will lead to excessive pesticide spraying and pesticide residues. Based on the ultrasonic sensor array, a small crop canopy volume calculation model is proposed, and the Pulse Width Modulation (PWM) control model of nozzle flow is established. The compensation time of opening and closing delay of the nozzle was determined to be 0.201 s by the high-speed photography method. The optimal operating speed was determined to be 0.3 m·s−1 through the benchmark test. Then, the precision variable spraying control method was integrated to develop the precision variable plant protection UAV based on an ultrasonic sensor array. The test results showed that the droplet deposition density was greater than 20 drop s·cm−2, and the droplet coverage rate of precision variable spraying was less than 30%. In the experimental area, the pesticide dosage of conventional and precision variable spraying was 0.24 L and 0.15 L, respectively, The precision variable-rate spraying saved pesticide usage by 34.5%. The system can realize precise variable spraying according to crop location and crop canopy volume changes. This study will promote the rapid development and application of precision spraying technology for small plant protection UAVs.
Vibration characteristics of the rotary table of large spin coater and its influencing factors
Authors: Ding Long , Zhang Xingang , Liu Qiuyu , Yan Ying , Zhou Ping
Published: August 2023

The rotary table vibration of the spin coater directly impacts the quality of the spin coating film. In view of the unclear vibration characteristics of the rotary table during operation, the rotary table vibration characteristics and its influencing factors considering the spindle system are studied. Based on the elastic contact theory and multi-body system theory, the rotary table vibration characteristics of the rotary table when the parts of the rotary table are flexible are analyzed by establishing the rotary table multi-rigid body and flexible coupling dynamics models, respectively. By comparing with the rotary table vibration measurement results, it is found that the flexible treatment of the load tray is more consistent with the actual vibration characteristics. The study further analyzes the effects of the unbalance of the rotary table, the rotary table speed, the coaxiality of the load tray and the spindle, and the perpendicularity of the load tray and the spindle on the vibration characteristics. The results show that the influence of the spin coater rotary table under the actual working conditions is from the highest to the lowest degree of influence on the unbalance of the load tray, the coaxiality of the load tray and the spindle, the perpendicularity of load tray and the spindle, and the rotational speed of the rotary table. This study provides a reliable theoretical and experimental basis for the vibration characteristics analysis and structural design of the spin coater rotary table.
Synthesis on cardioid crank rocker mechanism with approximate uniform motion
Authors: Han Haotong
Published: August 2023

The cardioid crank is a planetary mechanism that generates a cardioid line. It is a crank with varying length and speed that moves along the cardioid line. The cardioid crank is used to replace the crank of the crank rocker mechanism, and its rocker mechanism with approximate uniform motion is obtained. The kinematic analysis method of the cardioid crank rocker mechanism is studied in this paper. The calculating method for the limit position and oscillating angle and the time ratio of the guide bar are given. Finally, the approximate uniform motion conditions of the rocker are obtained. The synthesis method of the approximate uniform motion mechanism is put forward in accordance with the time ratio or rocker oscillate angle, the minimum length of the guide bar is calculated, and the influence of center distance on the kinematic performance of the mechanism is discussed.
Synthesis of cardioid crank rocker dwell mechanism
Authors: Du Zheng , Zhang Bowen , Han Jiguang
Published: August 2023

The cardioid crank rocker mechanism is a mechanism obtained by replacing the crank of a crank rocker mechanism with a cardioid crank. The cardioid crank is a planetary mechanism capable of generating cardioid curves. Using the cardioid crank as the driving crank of the crank rocker mechanism is equivalent to a crank with variable speed and length moving along the cardioid line, changing the motion characteristics of the rocker. The motion characteristics of the cardioid crank rocker mechanism are studied, and the limit position of the rocker and the calculation method of the intermittent interval is given. The influence of the planetary linkage length and center distance on the intermittent interval, and how to complete the mechanical design with known intermittent angle are discussed respectively, and a comprehensive analysis is made.
The compound control of a Stewart mechanism for automatic assembly via co-simulation
Authors: Liu Tong , Huang Haitao , Chen Dongdong
Published: August 2023

With the advantages of big bearing ability, strong stiffness, and high precision, the Stewart structure with six degrees of freedom (6-DOF) has found its way into the fields of military equipment, aeronautics, and astronautics. In this paper, a Stewart mechanism used for automatic docking is studied via the co-simulation approach. The low-speed performance with a heavy load is improved by the speed feedback compensation of parallel cylinders. Firstly, after trajectory planning, the compound control strategy with Coulomb-Viscous friction-based speed compensation is proposed. Subsequently, the co-simulation framework, including the structure model in LMS. Motion, the hydraulic model in AMEsim, and the control model in Matlab/Simulink are separately established with corresponding parameters. Finally, the compound control strategy is comparatively studied with displacement feedback alone. The control errors of cylinder displacement would decrease from ±1.0 mm to ±0.4 mm, which obviously improves the control performance.
Structural Optimization of the Lower Door of the Main Landing Gear of an Aircraft
Authors: Yang Guiqiang , He Ping , Wang Yi , Liu Chaoni
Published: August 2023

In this paper, the topology optimization algorithm is used to optimize the main structure of the main landing gear lower door of an aircraft by combining the structural strength, structural stiffness, and processing technology [1-2]. Considering the balance of structural weight, structural strength, and material distribution, the structural topology optimization design result with reasonable structure, good manufacturability, and moderate weight is finally obtained.
A Numerical Study of Complex Impact Loads on Thin-Walled Casing of Aeroengine Considering Turbine Guide Vane Structure1
Authors: Zhong Wenyuan , Li Jiaqi , Yang Zhongyu , Feng Yinli , Sun Tao
Published: August 2023

As the main load-bearing component of the aero-engine system, the thin-walled casings have the characteristics of large size, complex structure, thin wall, and large area. In addition to the harsh working environment, it is necessary to study applicable preventive measures to contain high-energy fragments to ensure flight safety. The complex load formed by the axial impact and circumferential torsion exerted by the turbine rotor on the exhaust casing is studied, and the model includes the turbine rotor. By analyzing the deformation and energy dissipation of the exhaust casing in the calculation results, the dynamic response of the power turbine and the exhaust casing in the complex impact load is obtained, and it is verified that the initial speed of the power turbine has no obvious relationship with the dynamic response and energy dissipation of the exhaust casing. At the same time, it is concluded that the axial velocity and aerodynamic force of the power turbine have a strong positive correlation with the complex impact load and dynamic response of the exhaust casing. In the follow-up studies and equivalent experiments, these conclusions can be used as a reference for further experimental design.
The Interfacial Thermal Resistance Properties Of GNPs/Epoxy Thermally Conductive Composites By Molecular Dynamics Simulation
Authors: Du Gang , Yang Jie , Chen Lu , Ji Wangwei , Li Guangmao , Wang Yong
Published: August 2023

With the increasing power density and integration degree of electrical equipment, the problem of excess heat production is serious. Existing data show that the thermal management capability of electrical equipment is a key factor affecting the performance of electrical equipment. Therefore, the development of high thermal conductivity composites is an effective solution to improve the thermal management ability of equipment and extend the working life of equipment. With the purpose of enhancing the heat conduction of epoxy resin, graphene sheets (GNPs) with high thermal conductivity were added. Based on the reverse nonequilibrium molecular dynamics simulation (RNEMD) method, the thermal conductivity simulation of epoxy resin equipped with GNPs was carried out. The simulation results showed that the heat conductivity of epoxy resin equipped with GNPs had been greatly improved.
Investigation on the tribological property of marine engine bearing
Authors: Du Fengming , Zeng Yunbo , Yan Shaolong
Published: August 2023

The marine engine is one of the core devices of the ship. With the continuous progress of science and technology, marine engines are developing towards high power density, and the related tribological problems are more prominent. As one of the most typical friction pairs of marine engines, the crankshaft-bearing bush bears more and more loads and presents a trend of increased wear. By studying the wear behavior of the bearing bush, it is possible to deeply grasp the bearing wear mechanism, speed up the research and development process of the bearing bush, and further improve the wear resistance. In this paper, for the crankshaft-bearing bush pairing pair, a component-level bearing bush friction and wear testing machine is built, and the corresponding test method is established. The binary electroplating bush and an alloy shaft pair are selected for the experiment, and the wear law of the bearing bush is explored.
Effects of Temperature on the parameters of the Electrochemical Impedance Spectroscopy for Lithium-Ion Batteries
Authors: Ma Jinyu , Wang Hongwei , Zheng Chun , Tao Ziqiang , Fu Yanling , Bai Hong , Xiao Haiqing
Published: August 2023

The health status of lithium-ion batteries and the acquisition of internal information for battery designs and health predictions are of great significance. Electrochemical impedance spectroscopy (EIS) is a measurement method that has received more and more attention in the research on lithium-ion batteries’ performance. In this paper, three kinds of lithium-ion batteries made of different materials were studied to measure the impedance at different temperatures. An equivalent circuit model (ECM) was established, and the effect of temperature on the impedance of different batteries during the data was studied. Temperature is considered an important parameter for predicting batteries’ states. The result shows that the batteries’ impedances at -40°C are hundreds of times higher than those at 75°C. The diffusion impedance and battery transfer impedance of the three batteries all increase with the decrease in temperature, but NMC and LTO batteries have a higher tolerance to high temperatures than LFP. It is concluded that EIS combined with temperature is significant to batteries’ state estimation and performance evaluation.
Temperature Field Analysis of Oil-Cooled Heat Dissipation in High-Speed Permanent Magnet Synchronous Motor
Authors: Yang Cunxiang , Zhang Kai , Qiu Hongbo
Published: August 2023

With the development of high-speed permanent magnet synchronous motors (PMSM), the requirements for speed are getting higher and higher, and the power density increase is getting bigger and bigger. However, too high a loss density will cause motor heat dissipation difficulties, resulting in motor insulation aging and permanent synchronous magnet demagnetization failure, which seriously affects the safe operation of the motor. Therefore, it is necessary to analyze the fluid field and temperature field for oil-cooled high-speed PMSM. In this paper, a 40 kW back-wound oil-cooled high-speed PMSM is used as the research object. Firstly, a three-dimensional fluid-solid coupled heat transfer model of high-speed PMSM is established based on the parameters of the motor, and the fluid flow characteristics inside the motor are analyzed based on fluid dynamics and heat transfer theory, and then the overall and local temperature rise distributions of the motor are compared and analyzed to reveal the influence of the temperature rise of each component inside the high-speed permanent magnet synchronous motor after being cooled by the cooling structure. Secondly, based on the finite element model, the motor temperature rises and oil flow characteristics with oil flow rate are analyzed to come up with an optimized solution. Finally, the accuracy of the analysis method is verified by conducting temperature rise experiments on the prototype.
Test Analysis of 220 kV Rotating Transmission Angle Tower
Authors: Sun Zhicheng , Zhang Aoyu , Li Xiaotong , Xue Yuan
Published: August 2023

As the requirements for the protection of environmental water in the construction of transmission lines have increased, the position of the tower in steep mountainous areas often fails to meet the requirements because of the difference in tower legs, which causes damage to the original landform, thus resulting in the change of the path and the increase of the project investment. In this paper, we optimize the design of a rotating steel tower to adapt to the steep terrain of mountainous areas and reduce the base surface opening. The feasibility of the proposed rotating tower optimization design is demonstrated by analyzing the real test data of the rotating tower.
A statistical characterization model of the microscale contact state of polishing pads
Authors: Shi Haosong , Di Hongyu , Zhou Ping , Guo Dongming
Published: August 2023

Chemical mechanical polishing (CMP) greatly benefits from the wafer and pad’s microscale contact condition. With so many varying pressures and wafer layouts, it is incredibly difficult to measure all the microscale contact states. Therefore, there is an urgent need to realistically characterize the morphology and contact state of polishing pads. A statistical characterization model of the microscale contact state of polishing pads was developed in this investigation. The microscale contact states under different pressures were measured to make sure that the model was accurate. This proposed model can extract the pad morphology parameters from the microscale contact state to predict the pad surface morphology and, thus, the microscale contact state in arbitrary conditions. This study can provide some recommendations for stability in CMP and the production and use of pads.
Modification of Multi-Functional Composites by Using Particles with High Thermal Conductivity to Improve Heat Management and Electromagnetic Shielding Performance
Authors: Zhao Minna , Xu Baosheng , Chen Yanfei
Published: August 2023

Packaging materials with thermal management and electromagnetic protection are designed to develop miniaturized high-power airborne electronic equipment and meet the overall design requirements. In this study, graphene/paraffin composite material modified by high thermal conductivity particles is used to improve thermal conductivity, thermal management efficiency, and electromagnetic performance. Four kinds of high thermal conductivity particles including nickel, silver, copper, and hexagonal boron nitride were selected. Modified phase change material composite with carbon matrix was prepared by melt blending and pressure molding. Microstructure, thermal conductivity, latent heat, and electromagnetic properties were tested. Particles with different high thermal conductivity values could be uniformly distributed in the composite material by melt blending. Adding particles can improve the thermal conductivity of the composite to varying degrees, and copper and silver can also improve the electromagnetic shielding effectiveness of the composite. The composite material added with silver particles has the best modification effect, with a 92.3% increase in thermal conductivity and a 32.8% increase in shielding efficiency.
The characteristics of porous baffles reducing the impact load of liquid nonlinear sloshing
Authors: Shen Minmin , Sun Chuanbin , Tong Baohong , Chen Cuiqian
Published: August 2023

The study aims to explore the characteristics of the impact load of a ship under the influence of a harsh marine environment. The horizontal excitation test platform is established to analyze the response law of the external excitation frequency of the sloshing load. Moreover, nonlinear liquid sloshing impact load characteristics are analyzed under porous baffling with different solids ratios and tanks with different liquid depths. It is found that the resonance frequency of the tank without baffling is 0.93ω
0, and that of the tank with a porous baffle is 0.96ω0. With the solid ratios of 0.4 to 0.8, the transient and steady state pressure peaks decrease by 66% and 71%, respectively. The liquid depths of H to H/4, for both transients and steady state pressure peaks, decreased by about 36%. It shows that the resonant frequency is closer to the natural frequency when the amplitude of liquid sloshing is reduced. When the solid ratio is smaller or the liquid depth increases, the impact load of liquid on the wall is stronger, and the double peak of impact load is more obvious. This provides a reference for the engineering design of the liquid tank and the study of fluid sloshing damping.
The Johnson-Cook Constitutive Model of TA19 Titanium Alloy
Authors: Tang Wenting , Liu Changli , Zhang Kaiming
Published: August 2023

In order to obtain the stress-strain relationship of the TA19 titanium at 10−3 s−1 to 4100 s−1 strain rates, a quasi-static tests and a Split Hopkinson Bar were performed at room temperature. The Johnson-Cook model analyzed and the parameters in the constitutive equation are fitted according to the experimental data. SHPB tests of TA19 titanium at strain rates of 1100 s−1, 2000 s−1, and 3300 s−1 were simulated by using ANSYS/LS-DYNA. Comparison of experimental data with simulation data shows that the J-C model can correctly reflect the material properties of TA19 titanium within a certain strain rate range.
Thermodynamic Calculation of 2618 High Performance Aluminum Alloy
Authors: Chen Shanshan , Huang Zicheng , Chai Zhizhang
Published: August 2023

The thermodynamic-related physical parameters, precipitation amount of equilibrium phase, and initial precipitation temperature of Al-(1.9–2.5) Cu-(1.2–1.8) Mg-(0.9–1.5) Fe-(0.9–1.5) Ni alloy were simulated by using the thermodynamic simulation software JMat-Pro. The results show that with the change of element content, the liquidus temperature is in the range of 641.92–638 °C. The precipitation transition temperature of the eutectic phase with a low melting point ranges from 515 °C to 517.25 °C. The solidus temperature is closely related to Cu/Mg. The dendrite spacing decreases with the increase of Mg and Fe (Ni) contents, among which Mg has the greatest influence, followed by Fe (Ni) and Cu. The partial molar Gibbs free energy of Cu, Mg, Fe, and Ni is negative. The activity of Mg increases with the decrease in temperature, and the maximum activity is 0.10189, while the activities of Cu, Fe, and Ni are close to 0. The initial precipitation temperatures of S(Al2CuMg) and Al9FeNi phases are 424–450 °C and 635.4–643.01 °C, respectively. The initial precipitation temperature of the Al9FeNi phase decreases with the increase of Cu and Mg contents, while it increases with the increase of Fe (Ni) contents. With the increase of Cu and Mg contents, the initial precipitation temperature of S(Al2CuMg) increases and decreases with the increase of Fe (Ni) contents. The precipitation amount of S(Al2CuMg) mainly depends on the content and ratio of Cu and Mg, while that of Al9FeNi increases with the increase of Fe and Ni elements in the same proportion.
Design of rapid erection system for transmission lines for disaster rescue
Authors: Zhao Bingliang , Guo Zhigang , Yang Wei , Lu Yanling
Published: August 2023

The rapid erection system of transmission lines in disaster relief can restore the power supply in the disaster area in a very short time. It takes a long time to construct transmission lines in post-disaster relief and reconstruction. This paper designs the transmission line erection system with the idea of light quality and modularization and puts forward the dimensions and structures of auxiliary hoisting towers and overhead towers. Then, considering that the transmission line is a tall flexible structure, which is very sensitive to wind load, the finite element model of the transmission tower is established to analyze the simultaneous stress of the overhead tower and the lifting tower under extreme conditions. The study verifies the feasibility and stability of the designed transmission line rapid erection system.
Multi-Scenario Clustering-Based Distribution Network with Distributed Power Sources Operational Risk Warning Method
Authors: Ouyang Wenhua , Chen Yaqi , Li Qiong , Meng Tianqi , Cai Muliang
Published: August 2023

Risk assessment of the operation of distribution networks containing distributed power sources is the most important way to ensure the safe operation of distribution networks. In this paper, the main objective of the study is to assess the risk of the distribution network with distributed photovoltaic (PV) based on time-series risk analysis in multiple scenarios. Firstly, the PV output and load demand power of each time of the year are composed of multi-series data, which are clustered into several typical scenarios throughout the year, and the corresponding weights are obtained. The risk assessment and analysis are carried out in each scenario, and the risk warning is carried out according to the warning criteria. The feasibility of the proposed method is verified using an IEEE 33-node distributed system example.