bluuebunny/crossref_metadata_2025 huggingface dataset:
A full-head model to investigate intra and extracochlear electric fields in cochlear implant stimulation
Authors: Callejón-Leblic M A , Lazo-Maestre M , Fratter A , Ropero-Romero F , Sánchez-Gómez S , Reina-Tosina J
Published: June 2024

Objective. Despite the widespread use and technical improvement of cochlear implant (CI) devices over past decades, further research into the bioelectric bases of CI stimulation is still needed. Various stimulation modes implemented by different CI manufacturers coexist, but their true clinical benefit remains unclear, probably due to the high inter-subject variability reported, which makes the prediction of CI outcomes and the optimal fitting of stimulation parameters challenging. A highly detailed full-head model that includes a cochlea and an electrode array is developed in this study to emulate intracochlear voltages and extracochlear current pathways through the head in CI stimulation. Approach. Simulations based on the finite element method were conducted under monopolar, bipolar, tripolar (TP), and partial TP modes, as well as for apical, medial, and basal electrodes. Variables simulated included: intracochlear voltages, electric field (EF) decay, electric potentials at the scalp and extracochlear currents through the head. To better understand CI side effects such as facial nerve stimulation, caused by spurious current leakage out from the cochlea, special emphasis is given to the analysis of the EF over the facial nerve. Main results. The model reasonably predicts EF magnitudes and trends previously reported in CI users. New relevant extracochlear current pathways through the head and brain tissues have been identified. Simulated results also show differences in the magnitude and distribution of the EF through different segments of the facial nerve upon different stimulation modes and electrodes, dependent on nerve and bone tissue conductivities. Significance. Full-head models prove useful tools to model intra and extracochlear EFs in CI stimulation. Our findings could prove useful in the design of future experimental studies to contrast FNS mechanisms upon stimulation of different electrodes and CI modes. The full-head model developed is freely available for the CI community for further research and use.
Global gyrokinetic study of density gradient driven instability in tokamaks: the ubiquitous mode
Authors: Choudhary Sagar , Chowdhury Jugal , M Gopal Krishna , Mahapatra Jagannath , Singh Amit K , Ganesh Rajaraman , Villard Laurent
Published: June 2024

The ubiquitous mode is investigated in the linear regime for the first time using a global gyrokinetic model. These modes are driven by the density gradient in trapped electron population but with mode frequency in the ion diamagnetic drift direction, in contrast to the conventional trapped electron mode. The dispersion relation is calculated along with the global mode structure. The ubiquitous mode is quite global although appears at a shorter wavelength (

1
2

k
y
2

ρ
i
2

>
1

). We show that the main driving mechanism is the density gradient and the temperature gradient has only a modest effect; the mode can persist at higher temperature gradient scenarios making it another possible channel of anomalous transport. The magnetic shear reduces the growth of the mode; while the electron to ion temperature ratio has a nonmonotonic effect on the mode growth rate—growth rate increases initially for the ubiquitous branch of the mode and decreases afterwards as the conventional trapped electron mode starts dominating. The role of safety factor and toroidicity is also analyzed. Finally, a mixing length-based estimation of transport is presented.
Addressing data scarcity using audio signal augmentation and deep learning for bolt looseness prediction
Authors: Chelimilla Nikesh , Chinthapenta Viswanath , Korla Srikanth
Published: June 2024

Deep learning models such as convolutional neural networks (CNNs) encounter challenges, including instability and overfitting, while predicting bolt looseness in data-scarce scenarios. In this study, we proposed a novel audio signal augmentation approach to classify bolt looseness in the event of data deficiency using CNN models. Audio signals at varied bolt torque conditions were extracted using the percussion method. Audio signal augmentation was performed using signal shifting and scaling strategies after segmenting the extracted audio signals. The unaugmented and augmented audio signals were transformed into scalograms using the continuous wavelet transform approach to train the CNN models. Upon training with augmented datasets, a promising improvement in the loss and accuracy of the CNN models in recognizing bolt looseness was noticed. One of the significant observations from the current study is that the implementation of audio signal augmentation improved the extrinsic generalization ability of the CNN models to classify bolt looseness. A maximum increase of 73.5% to identify bolt looseness in novel data was exhibited as compared to without augmentation. Overall, a maximum accuracy of 94.5% to classify bolt looseness in unseen data was demonstrated upon audio signal augmentation. In summary, the results affirm that the audio signal augmentation approach empowered the CNN models to predict bolt looseness in data-deficient scenarios accurately.
Role of blue-shift length in macroscopic properties of high-harmonic generation
Authors: Khokhlova Margarita , Strelkov Vasily
Published: June 2024

The production of brighter coherent XUV radiation by intense laser pulses through the process of high-harmonic generation (HHG) is one of the central challenges in contemporary nonlinear optics. We study the generation and spatial propagation of high harmonics analytically and via ab initio simulations. We focus on the length scales defining the growth of the harmonic signal with propagation distance and show that the well-known coherence length limits HHG only for relatively low driving intensities. For higher intensities, the photoionisation of the medium, naturally accompanying HHG, leads to essentially transient phase matching and laser frequency blue shift. By systematically taking both of these factors into account, we demonstrate that the behaviour of the harmonic signal at higher intensities is defined by another length scale—the blue-shift length. In this generation regime the XUV intensity at a given frequency first grows quadratically and then saturates passing the blue-shift length, but the total harmonic efficiency continues growing linearly due to the linear increase of the harmonic line bandwidth. The changeover to this generation regime takes place for all harmonic orders roughly simultaneously. The rate of the efficiency growth is maximal if the atomic dispersion is compensated by photoelectrons near the centre of the laser pulse. Our theory offers a robust way to choose the generation conditions that optimise the growth of the harmonic signal with propagation.
Nonequilibrium quantum heat transport between structured environments
Authors: Pleasance Graeme , Petruccione Francesco
Published: June 2024

We apply the hierarchical equations of motion technique to analyzing nonequilibrium heat transport in a spin-boson type model, whereby heat transfer through a central spin is mediated by an intermediate pair of coupled harmonic oscillators. The coupling between each pair of oscillators is shown to introduce a localized gap into the effective spectral densities characterizing the system–oscillator–reservoir interactions. Compared to the case of a single mediating oscillator, we find the heat current to be drastically modified at weak system-bath coupling. In particular, a second-order treatment fails to capture the correct steady-state behavior in this regime, which stems from the λ
4-scaling of the energy transfer rate to lowest order in the coupling strength λ. This leads naturally to a strong suppression in the steady-state current in the asymptotically weak coupling limit. On the other hand, the current noise follows the same scaling as in the single oscillator case in accordance with the fluctuation-dissipation theorem. Additionally, we find the heat current to be consistent with Fourier’s law even at large temperature bias. Our analysis highlights a novel mechanism for controlling heat transport in nanoscale systems based on tailoring the spectral properties of thermal environments.
DFT calculations of new Li-based halides Li2AgAlY6 (Y = Cl, Br, I) for energy conversion applications
Authors: Tanveer Wasif , Adeel Abbas Syed , Noor N A , Alanazi Yousef Mohammed , Mumtaz Sohail
Published: June 2024

Recently, lead-free halide double perovskite (DP) materials have got scholarly attention owing to their environmentally sustainable characteristic, excellent stability and potential applications in solar cells and renewable energy. In this present article, we computationally examined the mechanical, optoelectronic and thermoelectric characteristics of a discernible compound Li2AgAlY6 (Y = Cl, Br, I) using the density functional theory (DFT). The evaluation of tolerance factor (tf), lattice constant (a0), and formation enthalpy (Hf) confirms the structural and thermodynamic stability of the investigated double DPs, also elastic constants further elaborate the mechanically stable nature. The studied compounds have direct band gap of 3.6 eV, 2.6 eV and 1.2 eV for Li2AgAlCl6, Li2AgAlBr6 and Li2AgAlI6 respectively, indicating the diverse energy absorption applications from ultraviolet to visible region. We used semi-classical Boltzman theory to determine the figure of merit (ZT) and corresponding Seebeck Coefficient (S), which validates the electrical and thermoelectric conductivity for the compounds under investigation. The current investigation establishes a theoretical foundation for the examined DPs, essential for comprehending and comparing forthcoming experimental inquiries aimed at exploring diverse optoelectronic and thermoelectric applications.
Effects of axial and radial components of magnetic field on the electromagnetic resistive instabilities in hall thruster plasma
Authors: Bharti Saty Prakash , Singh Sukhmander
Published: June 2024

A theoretical model is developed to investigate the effect of the axial component of the magnetic field on the electromagnetic resistive instabilities in the Hall thruster. The axial component of the magnetic field plays a vital role in controlling the plasma flow and generating thrust in the Hall thruster. It also affects the magnetic topology and magnetic field lines in the Hall thruster. In the present paper, a dispersion relation for the electromagnetic resistive instabilities under the influence of the axial component of the magnetic field is derived. The obtained dispersion equation is solved numerically to study the propagating and growing waves in the magnetized plasmas. It is observed that the growth rate decreases with an axial component of the magnetic field, but it increases with a radial component of the magnetic field. When the axial component of the magnetic field is considered, the amplitude of the growth rate of the resistive instability dropped with azimuthal wavenumber, collision frequency and electron drift velocity by almost 21%, 35%, and 33%, respectively. When the value of drift velocity exceeds 4 ×106 m s−1, the influence of the axial component of the magnetic field appeared, and the growth rate reduced drastically.
The dielectric and radiation shielding features of Zn0.9Ni0.1Co2-xFexO4 nanopowder
Authors: Heiba Zein K , Arafat Shadia W , Badawi Ali , Mohamed Mohamed Bakr
Published: June 2024

Nano Zn0.9Ni0.1Co2-xFexO4 (x = 0, 0.05, 0.1, 0.15) specimens were synthesized utilizing the hydrothermal method. An extensive assessment was conducted on the structure and dielectric characteristics of the fabricated specimens. The synchrotron x-ray diffraction and scanning electron microscopy techniques were employed to analyze the formed phases and the morphological characteristics of the specimens. Rietveld refinement was utilized for determining the structural and microstructural parameters of all specimens. The impact of temperature and frequency on the dielectric properties of the material is thoroughly investigated. Except for the specimen with x = 0.15, all samples exhibit ferroelectric characteristics. The electric modulus corroborated the existence of the non-Debye relaxation phenomenon and the presence of relaxation times distributed at a specific frequency. Each specimen demonstrates a singular relaxation time, which was modified by the introduction of Fe ions. Through the utilization of the Phy-X/PSD software, the radiation shielding parameters for the examined specimens were computed across a wide energy spectrum ranging from 15 KeV to 15 MeV. These parameters encompass the linear attenuation coefficients (LAC), mean free path (MFP), mass attenuation coefficient (MAC), half value length (HVL), effective nuclear number (Z
eff), and fast neutron removal cross-section (FNRCS). The specimens of Zn0.9Ni0.1Co2-xFexO4 exhibit elevated FNRCS values compared to RS-253-G18, RS-360, and RS-520 commercial shielding glasses.
DISCO-DJ I: a differentiable Einstein-Boltzmann solver for cosmology
Authors: Hahn Oliver , List Florian , Porqueres Natalia
Published: June 2024

We present the Einstein-Boltzmann module of the Disco-Dj (DIfferentiable Simulations for COsmology — Done with J
ax) software package. This module implements a fully differentiable solver for the linearised cosmological Einstein-Boltzmann equations in the Jax framework, and allows computing Jacobian matrices of all solver output with respect to all input parameters using automatic differentiation. This implies that along with the solution for a given set of parameters, the tangent hyperplane in parameter space is known as well, which is a key ingredient for cosmological inference and forecasting problems as well as for many other applications. We discuss our implementation and demonstrate that our solver agrees at the per-mille level with the existing non-differentiable solvers Camb and Class, including massive neutrinos and a dark energy fluid with parameterised equation of state. We illustrate the dependence of various summary statistics in large-scale structure cosmology on model parameters using the differentiable solver, and finally demonstrate how it can be easily used for Fisher forecasting, with a forecast for Euclid as an example. Since the implementation is significantly shorter and more modular than existing solvers, we believe it will be more straightforward to extend our solver to include additional physics, such as additional dark energy and dark matter models, modified gravity, or other non-standard physics in the future.
Stability of ECoG high gamma signals during speech and implications for a speech BCI system in an individual with ALS: a year-long longitudinal study
Authors: Wyse-Sookoo Kimberley , Luo Shiyu , Candrea Daniel , Schippers Anouck , Tippett Donna C , Wester Brock , Fifer Matthew , Vansteensel Mariska J , Ramsey Nick F , Crone Nathan E
Published: June 2024

Objective. Speech brain–computer interfaces (BCIs) have the potential to augment communication in individuals with impaired speech due to muscle weakness, for example in amyotrophic lateral sclerosis (ALS) and other neurological disorders. However, to achieve long-term, reliable use of a speech BCI, it is essential for speech-related neural signal changes to be stable over long periods of time. Here we study, for the first time, the stability of speech-related electrocorticographic (ECoG) signals recorded from a chronically implanted ECoG BCI over a 12 month period. Approach. ECoG signals were recorded by an ECoG array implanted over the ventral sensorimotor cortex in a clinical trial participant with ALS. Because ECoG-based speech decoding has most often relied on broadband high gamma (HG) signal changes relative to baseline (non-speech) conditions, we studied longitudinal changes of HG band power at baseline and during speech, and we compared these with residual high frequency noise levels at baseline. Stability was further assessed by longitudinal measurements of signal-to-noise ratio, activation ratio, and peak speech-related HG response magnitude (HG response peaks). Lastly, we analyzed the stability of the event-related HG power changes (HG responses) for individual syllables at each electrode. Main Results. We found that speech-related ECoG signal responses were stable over a range of syllables activating different articulators for the first year after implantation. Significance. Together, our results indicate that ECoG can be a stable recording modality for long-term speech BCI systems for those living with severe paralysis. Clinical Trial Information. ClinicalTrials.gov, registration number NCT03567213.
A machine learning artefact detection method for single-channel infant event-related potential studies
Authors: Marchant Simon , van der Vaart Marianne , Pillay Kirubin , Baxter Luke , Bhatt Aomesh , Fitzgibbon Sean , Hartley Caroline , Slater Rebeccah
Published: June 2024

Objective. Automated detection of artefact in stimulus-evoked electroencephalographic (EEG) data recorded in neonates will improve the reproducibility and speed of analysis in clinical research compared with manual identification of artefact. Some studies use very short, single-channel epochs of EEG data with little recorded EEG per infant—for example because the clinical vulnerability of the infants limits access for recording. Current artefact-detection methods that perform well on adult data and resting-state and multi-channel data in infants are not suitable for this application. The aim of this study was to create and test an automated method of detecting artefact in single-channel 1500 ms epochs of infant EEG. Approach. A total of 410 epochs of EEG were used, collected from 160 infants of 28–43 weeks postmenstrual age. This dataset—which was balanced to include epochs of background activity and responses to visual, auditory, tactile and noxious stimuli—was presented to seven independent raters, who independently labelled the epochs according to whether or not they were able to visually identify artefacts. The data was split into a training set (340 epochs) and an independent test set (70 epochs). A random forest model was trained to identify epochs as either artefact or not artefact. Main results. This model performs well, achieving a balanced accuracy of 0.81, which is as good as manual review of data. Accuracy was not significantly related to the infant age or type of stimulus. Significance. This method provides an objective tool for automated artefact rejection for short epoch, single-channel EEG in neonates and could increase the utility of EEG in neonates in both the clinical and research setting.
Rotational and translational dynamics and rheology in a granular system
Authors: Espinosa-Rodríguez José , Díaz-Leyva Pedro , Sánchez Rodrigo
Published: June 2024

The present work examines the translational and rotational dynamics, as well as their implications for system rheology, of an experimental granular system at an agitated air/water interface. A decoupling of rotational and translational dynamics is found. The translational dynamics is well-described by a modified Voigt model compatible to that obtained for prior simulational work, whereas the rotational motion alternates between two distinct states. The latter behaviour is accounted for in terms of collective effects at the edges.
Bethe M-layer construction on the Ising model
Authors: Angelini Maria Chiara , Palazzi Saverio , Parisi Giorgio , Rizzo Tommaso
Published: June 2024

In statistical physics, one of the standard methods to study second order phase transitions is the renormalization group that usually leads to an expansion around the corresponding fully connected solution. Unfortunately, often in disordered models, some important finite dimensional second-order phase transitions are qualitatively different or absent in the corresponding fully connected model: in such cases the standard expansion fails. Recently, a new method, the M-layer one, has been introduced that performs an expansion around a different soluble mean field model: the Bethe lattice one. This new method has been already used to compute the upper critical dimension

D
U

of different disordered systems such as the Random Field Ising model or the Spin glass model with field. If then one wants to go beyond and construct an expansion around

D
U

to understand how critical quantities get renormalized, the actual computation of all the numerical factors is needed. This next step has still not been performed, being technically more involved. In this paper we perform this computation for the ferromagnetic Ising model without quenched disorder, in finite dimensions: we show that, at one-loop order inside the M-layer approach, we recover the continuum quartic field theory and we are able to identify the coupling constant g and the other parameters of the theory, as a function of macroscopic and microscopic details of the model such as the lattice spacing, the physical lattice dimension and the temperature. This is a fundamental step that will help in applying in the future the same techniques to more complicated systems, for which the standard field theoretical approach is impracticable.
Advancements and Challenges in Linear Friction Welding of Inconel 718: A Comprehensive Review
Authors: Pawade Sneha , Raut Laukik , Biradar Akash , Bhushan Abhishek , Kolhe Mohini
Published: June 2024

This comprehensive review explores the linear friction welding of Inconel 718, a super alloy widely employed in aerospace and other high-temperature applications. Delving into the intricate relationship between process parameters and material properties, the paper examines microstructural transformations and their impact on mechanical integrity. Discussions encompass weldability, common defects, and mitigation strategies, providing valuable insights for practitioners. The review also highlights the evolving landscape of research trends, recent developments, and real-world applications, showcasing the versatility of linear friction welding. Challenges in the process are analyzed, offering a nuanced perspective on current limitations and avenues for improvement. Through a comparative lens with traditional welding techniques, the paper elucidates the unique advantages of linear friction welding in enhancing efficiency and performance. This synthesis of knowledge contributes to a holistic understanding of the state-of-the-art in linear friction welding of Inconel 718, presenting opportunities for future advancements in this critical domain.
Experimental Investigation of tool wear, surface roughness during milling of EN 25 steel using coconut based vegetable oil
Authors: Jhodkar Durwesh , Karanjekar Somadatta , Chede Bharat , Bajpai Tapus , Shukla Sourabh
Published: June 2024

In this study experimental investigation for utilization of coconut-based vegetable oil as an environmentally sustainable cutting fluid in the milling of EN 25 steel. The study focuses on evaluating the influence of coconut oil as cutting fluid during milling operation. A series of milling experiments were conducted, varying cutting parameters and employing carbide cutting tools, to systematically assess the performance of the coconut-based oil. The results demonstrate that coconut-based vegetable oil exhibits significant potential as a viable alternative to conventional cutting fluids. It not only effectively lubricates the machining process but also substantially reduces surface roughness and tool wear during milling of EN 25 steel workpiece. Advancing eco-friendly machining practices; this research not only contributes to reducing the environmental footprint of machining operations but also offers a promising solution to enhance machining efficiency. The findings presented in this study offer valuable insights for the practical implementation of this sustainable cutting fluid in industrial machining processes, setting the stage for further exploration and adoption of eco-friendly alternatives in the manufacturing industry.
Recent development in feeding mechanism of sheet metal shearing machine for productivity improvement: A review
Authors: Santape V N , Khond V W , Kota A B
Published: June 2024

Sheet metal working processes find extensive applications in industries such as automobile and aerospace. However, the sharp edges of sheet metal pose a safety hazard to workers, potentially leading to injuries. In response to this concern, we have conceived and developed an automatic sheet metal cutting machine. Feeding mechanism is one of the important part of sheet metal shearing machine. In this paper, recent research papers are reviewed. This papers also reports recent development in feeding mechanism and its role for productivity improvement. Also, proposed innovative feeding mechanism represents a pivotal advancement in the field of mechanical workshops, aligning with industry demands for increased productivity and safety in sheet metal processing. Paper throws lights on benefits of automation into the sheet metal cutting process, which a significantly reduces in labour costs while ensuring precise and efficient cutting operations. Paper also focuses the various parameter such as cutting speed, material properties.
Modal analysis of tripod-ball type universal coupling composite transmission shaft system
Authors: Xiu Xia , Chang Degong
Published: June 2024

In order to improve the dynamic performance of the tripod-ball type universal coupling composite transmission shaft system, ANSYS Workbench modal analysis is carried out. By modal analysis of the transmission shaft system, the vibration characteristics of the coupling have been obtained, which can avoid its natural frequency in practical situations. The figures for the first ten modes have been obtained. The results indicate that the areas with the greatest deformation are on the intermediate shaft, bell housing, and trident sleeve. This provides a theoretical basis for further research on the transmission shaft system.
Optimization of transcutaneous energy transmission system suitable for implanted devices
Authors: Han Ding , Qian Dahong , Yan Guozheng , Kuang Shuai , Wen Renqing , Xiang Suncheng
Published: June 2024

Microdevices have been implanted in the body to diagnose diseases and treat functional disorders, such as an artificial sphincter for fecal incontinence. Since these devices are expected to work in the body as long as possible, the energy supply has become increasingly important. Wireless power transfer (WPT) systems are suitable for medically implanted devices. A transcutaneous energy transmission (TET) system, as one of the wireless power transfer systems, is discussed in this article. A TET system comprises two coils: a transmitter coil and a receiver coil. First, a serial-serial resonance circuit is adopted in the TET system by different resonance circuits’ efficiency analysis. In addition, coil features, such as magnetic field intensity, coil outer diameter, coil turns, and coil inner diameter, have been investigated in detail to improve the inductive coupling coefficient, leading to a high-power transmission efficiency. The proposed TET system with the optimal parameters is used in the in vivo experiments. Experiments using an optimized wireless power transfer system show a better performance than previous (before optimization) with a 38% increase in efficiency.
Design and implementation of adaptive control for industrial robot servo trajectory tracking
Authors: Liu Jiale , Zhao Ting , Huang Shifeng
Published: June 2024

To cope with the complex external environment of the robot, an online adaptive control method for industrial robots is implemented by using robot dynamic parameters as control variables. A Newton-Euler method is implemented to establish a rigid body dynamics model for the robot. Subsequently, we confirm the possibility of dynamic parameter adaptive control by employing the Lyapunov stability theory and derive the dynamic parameter estimation law. Three methods are proposed to realize the observation matrix containing reference information in the adaptive control algorithm. Through physical experiments, it is verified that the dynamic parameter adaptive control is superior to traditional PPI control, and its position tracking error and anti-interference ability are significantly improved.
Design of FPGA-based data acquisition system for nanoparticle counting
Authors: Fan Cundong , Chen Liang , Li Yu
Published: June 2024

As one of the effective means to monitor the environment, the number of particles in the air is gradually developing towards smaller nanoparticles. To improve the acquisition speed of nanoparticle signals and the count of the number of particle signals, this paper adopts the FPGA of Altera as the main control chip, combined with the high-speed ADC AD9280. The sampling of the particle pulse signal is realized, and the collected data is transmitted to the host computer through serial communication. Through the designed peak detection algorithm, the algorithm is hardware accelerated to realize real-time continuous processing of particle signal, calculate the number of peaks, and then get the number of particles. In this paper, the hardware circuit and FPGA logic design of the system are described, and the acquisition system is tested. The results show that the system can meet the requirements.
Structural design and kinematic analysis study of ultrasonic flaw detection robot
Authors: Zhai Haoran , Zhang Ziming
Published: June 2024

A five-degree-of-freedom robot design scheme for liquid immersion ultrasonic flaw detection is proposed to address the challenges in complex surface ultrasonic flaw detection. To meet the requirements of underwater working environments, an XYZ+AB-type robot, which improves part of its structure, is adopted. A kinematic model of the robot is established using improved D-H parameters to obtain the forward and inverse kinematics of the robot. Based on the kinematic model, the simulation model of the robot is established by using the Matlab toolbox, which verifies the rationality of the design and the correctness of kinematics. The robot designed in this plan mainly targets thin-walled parts, such as aircraft skin and engine blades, with a repeat positioning accuracy of 0.01 mm and a detection speed of 120 mm/s. Compared with foreign high-degree-of-freedom penetrative flaw detection robots, the hardware cost of the robot in this plan can be reduced by half.
The Influence of the external meshing gears’ contact ratio on the contact stress in the transmission system
Authors: Li Fajia , Tang Xin , Liang Xiao , Sha Jian , Shen Rui , Liu Haining , Wu Ziheng
Published: June 2024

Using the Hertz contact theory, the calculation method of tooth contact stresses at different boundary points within the double tooth meshing zone for high contact ratio external meshing gear pair is investigated. The radius of curvature and pressure angle at each boundary point of the external meshing gear with a high contact ratio is given. The boundary point meshing coefficients are introduced to convert the comprehensive radius of curvature at the boundary point into the radius of curvature at the node, to make it in line with the form of calculation of the national standard. The analysis examines how the parameters affect the contact stress at different boundary points of the gear pair with a high contact ratio. When the contact ratio of the gears is 2, there is a sudden change in the contact stress on the tooth surface, and HCR gears have smaller contact stress than LCR gears.
Aerodynamic interaction characteristics analysis of intermeshing-rotor fuselage in hover
Authors: Yang Zhikun , Li Jingyang , Yu Hao , Baoyin Hexi
Published: June 2024

To study the interference characteristics of the intermeshing-rotor fuselage, a numerical simulation method for the flow field of a crossed twin-rotor helicopter in a hovering state is established based on the lattice Boltzmann method. The effectiveness of the proposed numerical simulation method is first verified by the ROBIN helicopter rotor/fuselage interference example. Then, taking the simplified JZ-60 rotor and S-97 helicopter fuselage as the research objects, the aerodynamic interference characteristics of the intermeshing rotor and the fuselage are investigated, and the aerodynamic interference law between the two under the hovering state is obtained. The results show that the intermeshing rotor has periodic tension fluctuation, and the fuselage interference leads to about a 4% increase in the total tension of the rotor. The maximum hovering efficiency increases by about 5%, and the larger the tension coefficient is, the larger the fuselage gains on the hovering efficiency is. The fuselage generates periodic negative lift and lateral force under the influence of the rotor. The hovering efficiency gains of the rotor mainly originate from the increases of the blade lift coefficients in the vicinity of the azimuth angles of 0° and 180°. The rotor is in the range of 0.5° and 180°, which has the strongest interference effect on the fuselage near 0.6 R and -0.7 R.
Research on the induced vibration force characteristics of lateral propulsion propeller
Authors: Zhong Yan , Zhang Liang , Lu Ben , Zhu Hua
Published: June 2024

This article conducts unsteady numerical calculations on lateral thrusters under arrival conditions, revealing the induced unsteady force characteristics under the interference between lateral thrusters and pod packages. The calculation results show that the lateral force and torque of the lateral propeller point towards the bow of the ship, and the main characteristic frequencies of pressure pulsation are blade frequency and its harmonics; The thrust and torque pulsation of the side thrusters on the bow side of the ship have maximum values; The bottom of the lateral thrust channel exhibits stronger pressure pulsation compared to other positions. The calculation results of this article determine the position and characterization form of the excitation force of the lateral thruster, providing a basis for the design of low-noise lateral thrusters.
Electromagnetic noise characteristics analysis and noise traceability in induction motor
Authors: Cheng Yiyang , Wang Zhen , Zhang Yuanxia
Published: June 2024

To investigate the electromagnetic vibration and noise issues in induction motors, this study employs a combined methodology of experimental, theoretical, and simulation approaches to analyze the characteristics of electromagnetic noise. Initially, a theoretical analysis of the radial electromagnetic force of the motor is conducted, followed by a simulation of the motor’s electromagnetic vibration and noise at a working condition of 3000 rpm, incorporating a Multiphysics coupled analysis of electromagnetic-vibration-noise. Vibration testing on a specific compressor motor reveals that the primary vibration noise characteristic frequency is centered around 2000 Hz. A comparison between simulation and experimental results shows a high degree of congruence, indicating the reliability of the simulation method. Subsequently, an acoustic camera kit, Brüel & Kjær PULSE Reflex, based on a beamforming method, is employed for noise source identification and acoustic holography testing at 3000 rpm, which successfully localizes the noise sources. The analysis and experiments provided herein can serve as a reference for the development of electromagnetic vibration noise suppression techniques in induction motors.
Analysis of crack propagation and life estimation of spiral bevel gears with root cracks
Authors: Yang Hang , Zhang Weiqing , Wang Ning , Tan Rulong
Published: June 2024

In order to study the effect of tooth root cracks on the fatigue life of spiral bevel gears, a certain spiral bevel gear was taken as the research object, and the mechanism of tooth root fatigue cracks was analyzed based on crack propagation theory; By combining the extended finite element method and the level set method, an initial crack propagation finite element model is established. The crack location of the gear teeth is determined through static analysis of the gear pair, and the influence of alternating loads on the initiation and propagation life of tooth surface cracks is studied. The analysis results indicate that the number of load cycles required for each crack propagation after its first occurrence gradually decreases; The crack propagation path of gear cracks under fatigue load is consistent with the actual tooth surface fracture surface; Realize life estimation from crack propagation to fracture failure.
Tracking control of flexible link manipulator with joint space constraints
Authors: Jing Feng , Ma Caiwen , Cao Yu , Xie Meilin , Wang Fan , Liu Peng , Fan Xiao
Published: June 2024

A controller design with system uncertainties, external disturbances, and joint space constraints for a flexible link manipulator (FLM) is presented in this paper. To overcome the lumped disturbance and ensure that the joint space constraints are not violated, a finite-time extended state observer (ESO) and a barrier Lyapunov function are constructed. Using Lyapunov’s theory, the error of the system is proved to be semi-globally ultimately uniformly bounded without violating the constraints. Finally, the rationality of the proposed methodology is verified by numerical simulation.
Visual evaluation and information improvement method of smart factory layout based on information value added
Authors: Wang Jikai , Dou Yajie , Ouyang Weijun , Dai Yulong , Yang Kewei
Published: June 2024

The process of Industry 4.0 is constantly promoted. In order to realize the high-quality connotation development of enterprises, manufacturing enterprises need to carry out information transformation and upgrading. The technology of information flow analysis can consistently assess the worth of the factory, overcome existing technical challenges, and achieve intelligent modernization and enhancement of the system. This study presents a visualization and evaluation of the factory’s layout, production lines, and workstation from three perspectives: macro, meso, and micro. To begin, a value added heat map (VAHM) is created by examining the visualization technique for information value added information (IVA). This analysis aims to assess the extent of information wastage in terms of the factory’s physical space, resources, and staff. Additionally, a method for analyzing the information gain of a production line, which is based on the concept of distributed cognition, is introduced. This method evaluates the production line by integrating the economic principle of information processing (EPIP). Furthermore, when assessing complexity, the volume of information in workstations is measured and enhanced by applying the principle of information processing economy. Ultimately, the method’s validity and feasibility are confirmed by applying it to real-world manufacturing industry scenarios.
Research on tightly coupled SLAM method based on LiDAR/IMU
Authors: Zhan Yiyuan , Wang Yong , Li Yanqiang , Du Qian , Qi Xiaobin
Published: June 2024

Aiming at the problems of insufficient accuracy and serious computational time-consumption of mainstream laser odometry schemes, this paper proposes an innovative solution, where the front end is based on the idea of iterative Kalman filtering, which realizes the tight coupling of inertial measurement unit (IMU) and LiDAR to obtain high-precision position and attitude estimation. The back-end optimization employs a factor graph approach, incorporating laser odometry, IMU preintegration, and loop closure detection factors. In comparison with state-of-the-art laser SLAM algorithms, the SLAM algorithm proposed in this paper reduces the absolute position error of trajectories by 9.61%, 91.03%, and 94.89% compared to Fast-lio2, Lego-loam, and a-loam, respectively.
Tool wear image segmentation algorithm based on K-means clustering
Authors: Liu Bengang , Wu Wenjiang , Zhang Yunpeng , Dong Zeguang , Li Baode
Published: June 2024

The existing tool wear region segmentation and detection methods make it difficult to achieve accurate detection of tool wear images under the conditions of noise interference. To further improve the detection efficiency and detection accuracy, combined with the characteristics of tool wear, this paper proposes a tool wear image segmentation algorithm based on K-means clustering to achieve accurate detection of tool wear images. Firstly, the acquired image is pre-processed to reduce the image processing computation and optimize the image, filter out the noise, and reduce the interference of the image. Then K-means clustering is used to cluster the surface features of the image, and then a threshold segmentation algorithm is used to locate the tool wear area and segment it out. The final experimental results show that the segmentation accuracy of this method is high and can be applied to tool wear area detection.
Research on four-sided differential localization algorithm for automated guided vehicles based on ultra-wideband
Authors: Sha Jinzhao , Zhang Shouxiang
Published: June 2024

To meet the high-precision positioning and navigation requirements of automated guided vehicles (AGV) in environments such as factories and workshops, this study utilizes ultra-wideband (UWB) positioning technology and designs a multi-tag differential localization algorithm to enhance the positioning accuracy of AGV. Starting from the current research status of AGV positioning and navigation, the paper provides a detailed introduction to the concept, process, and practical applications of the UWB differential localization algorithm. The maximum static positioning accuracy for UWB is 64 mm, and the maximum dynamic positioning accuracy is 222 mm, thereby meeting the requirements for AGV positioning and navigation.
Research on an optimal allocation method of energy storage system for peak-shaving and valley-filling
Authors: Xu Pengfei , Jiang Ruofei , Tian Xing , Cao Jiajing , Li Guojie , Zhang Tong , Li Yan , Wang Qing , Liu Hongwei
Published: June 2024

In recent years, the economy has developed rapidly, and the power load has also increased substantially. As a result, the peak-valley load gap also increases gradually, which is not conducive to the stable operation of the power grid. Energy storage system (ESS) has the function of time-space transfer of energy and can be used for peak-shaving and valley-filling. Therefore, an optimal allocation method of ESS is proposed, which is applied to reduce the load gap between peak and valley. Firstly, load standard deviation is used as the index of peak-shaving and valley-filling effects. The comprehensive cost of the ESS is converted to days as an economic indicator. Then, the comprehensive cost and load standard deviation are taken as the optimization objectives and are linearly weighted. Finally, the GUROBI toolkit is called in MATLAB to solve the example, and the optimal allocation of the ESS is obtained. By comparing the load curves before and after the allocation of ESS, the analysis shows that the peak-valley difference of load decreases after the ESS is configured, which proves that the optimal allocation method of ESS is effective.
Optimization of multi-integrated energy microgrid scheduling under carbon trading mechanism
Authors: Lin Hong , Ma Yue
Published: June 2024

Realizing the power transaction and benefit distribution among multi-integrated energy microgrids with different interests in the system, a multi-microgrid cooperative operation optimization scheduling method under a carbon-trading mechanism is proposed. Considering the microgrid’s electric energy interaction, a model of multi-microgrid cooperation is established. The multi-microgrid cooperative game model is equivalently transformed into two sub-problems, multi-microgrid cooperative operation cost minimization and internal power transaction bargaining, and to solve the two sub-problems successively. The simulation results show that the method is valid.
Convex optimization topology identification of distribution network under distributed conditions
Authors: Zhou Yujie , Li Zhuoqin , Bao Xingyu , Mo Bowen
Published: June 2024

The distributed phenomenon will occupy a very important proportion in the future distribution network. In order to ensure the stable operation of the power system, it is very important to study the topological adaptability identification of new distribution networks. In this paper, an adaptive topology identification regression matrix for a low-voltage distribution network is proposed, which is combined with a convex optimization algorithm to build a topology identification model for a low-voltage distribution network. This method can identify the topology of the distribution network accurately, which is helpful to improve the operation efficiency and safety of the power system.
Research on power transformer maintenance strategy based on case-based reasoning
Authors: Zhong Yuanchen , Yuan Ting , Chen Bibo , Fan Guangliang
Published: June 2024

In the past, the development of transformer maintenance strategies mostly used information data from a single source, and the final strategy was too general, unable to intelligently and automatically achieve effective guidance for equipment operation and maintenance. Based on existing case sets, this article studies case representation, feature attributes and weights, and a maintenance decision algorithm based on case-based reasoning. Firstly, the structural similarity between the target problem and the source case is analyzed, then the similarity between the two attributes is analyzed, and finally, the global similarity is calculated to modify and reuse the maintenance strategy of historical cases and retain new cases. The results show that the fault characteristics of the power transformer can be accurately grasped, and a reasonable maintenance strategy can be formulated to reduce the maintenance cost.
Study on rapid arc quenching in protection gap based on magnetic blowing principle
Authors: Shan Songyi , Yang Tingfang , Zhou Huikang , Xie Zelong , Zhou Qianghui
Published: June 2024

Parallel protection gap has the advantages of simple structure, good economy, and so on. It is widely used in lightning protection. However, the problem is that the arc’s self-extinguishing ability of the protection gap is poor and prone to tripping the line, hindering its further development. To address this problem, this paper proposes a method of connecting an electromagnet in series next to a protection gap and installing an arc-breaking grid at the gap. By changing the magnetic field distribution in the protective gap, while the arc is stretched, the arc is deflected to break on the arc-breaking grids, thus causing the arc to extinguish quickly. Through a finite element simulation platform, the arc simulation model of this protective gap was established based on the theory of magnetohydrodynamic (MHD) approach. The results of the study show that a fast arc quenching method for parallel protection gaps based on the magnetic blowing principle can extinguish the arc within 5 ms, an 89.4 percent reduction in arc extinguishing time compared to the traditional parallel spark gap. Its arc temperature plummeted to below 2000 K in a short time, which greatly reduces the arc energy and effectively improves the arc extinguishing effect of the protection gap.