bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatically detecting OSAHS patients based on transfer learning and model fusion
Authors: Ding Li , Peng Jianxin , Song Lijuan , Zhang Xiaowen
Published: May 2024

Objective. Snoring is the most typical symptom of obstructive sleep apnea hypopnea syndrome (OSAHS) that can be used to develop a non-invasive approach for automatically detecting OSAHS patients. Approach. In this work, a model based on transfer learning and model fusion was applied to classify simple snorers and OSAHS patients. Three kinds of basic models were constructed based on pretrained Visual Geometry Group-16 (VGG16), pretrained audio neural networks (PANN), and Mel-frequency cepstral coefficient (MFCC). The XGBoost was used to select features based on feature importance, the majority voting strategy was applied to fuse these basic models and leave-one-subject-out cross validation was used to evaluate the proposed model. Main results. The results show that the fused model embedded with top-5 VGG16 features, top-5 PANN features, and MFCC feature can correctly identify OSAHS patients (AHI > 5) with 100% accuracy. Significance. The proposed fused model provides a good classification performance with lower computational cost and higher robustness that makes detecting OSAHS patients at home possible.
Optimization of the on/off status configuration of control units in an active vibration isolation system—experiment
Authors: Wu Di , Zheng Shiruo , He Peitao , Zhang Zhiyi
Published: May 2024

Active vibration isolation (AVI) is an important measure to attenuate vibration transmission in underwater vehicles and multiple active control units are usually used to attenuate low frequency vibrations induced by power equipment. Under certain operation conditions, however, the pre-installed control units in an AVI system may be redundant. Hence, it is necessary to optimize the on/off status configuration of all the control units. An optimization approach is proposed for configuration optimization of control units and validated by experiments. The criterion of the proposed approach is derived from the vibration responses of the monitoring points. The involved optimization, formulated as a constrained 0–1 nonlinear programming problem, utilizes the on/off status of control units as the input variable and the number of active units as the constraint. Optimized configurations were obtained by solving the nonlinear programming problem and deployed to the experimental system. The test results have demonstrated that vibration of the monitoring points can be effectively suppressed by activating only a portion of control units, and the configurations corresponding to maximum vibration reduction vary with different excitations.
Experiment and simulation study on the functional fatigue of shape memory alloy beam actuators
Authors: Wang Xiaoyuan , Leng Jiaming , Rao Zhixiang , Yan Xiaojun
Published: May 2024

The functional fatigue behavior of shape memory alloy (SMA) beam actuators is gaining importance as their utilization in engineering applications becomes more widespread. However, research on the functional fatigue behavior of SMA beam actuators under bending conditions is not as extensive as that on SMA wires. In this paper, an experimental study and theoretical analysis of the functional fatigue behavior of SMA beam actuators were conducted. A measuring method for bending deflection and an automatic thermal cyclic test bench was designed. A series of functional fatigue tests were conducted on SMA beam actuators under different bias load conditions and the functional fatigue patterns were obtained. The material damage factor is defined and calculated through specimen tests. By incorporating the damage factor to modify the existing constitutive model, a model considering functional fatigue and tension-compression asymmetry is obtained. Finite element analysis (FEA) is performed based on this modified model to simulate the actuating performance of SMA beam actuators and to compute the deflection at different numbers of cycles. Additionally, a small parameter study on the actuator shape is conducted using FEA. By comparing the FEA results with functional fatigue experimental data, the effectiveness of the modified model is validated, demonstrating its capability to describe functional fatigue and predict actuator lifespan.
Parameters optimization of solar PV cell using genetic-iterative algorithm
Authors: Ben Said Y , Nouri L , Sakhi Z , Bennai M
Published: May 2024

Accurately determining optimal parameters from current-voltage (IV) data in solar photovoltaic (PV) models is crucial for effective system simulation and control. In this study, we propose a novel approach that combines genetic algorithm and iterative techniques maximizing their strengths, and exploiting the influence of each parameter on the IV curve to categorize them into groups. This adaptable method can adjust the interval of each parameter to different scenarios during optimization. We evaluated the method across various solar cell models including both the ‘SDM’ and ‘SDM-based PMM’, achieving notable accuracy and reliability compared to other advanced meta-heuristic algorithms. The results indicate a value of 7.3870e-5 for the SDM and 9.3365e-4 for the PMM (STM6-40/36). The proposed algorithm demonstrates notable accuracy and reliability, highlighting its usefulness in accurately determining parameters in solar PV models.
A two-symmetric electrode hydride supercapacitor developed from G-C3N4 decorated with poly-2-aminobenzenethiol
Authors: Ben Gouider Trabelsi Amira , Rabia Mohamed , Alkallas Fatemah H , Esayed Asma M
Published: May 2024

The incorporation of poly-2-aminobenzene thiol (P2ABT) onto 2D g-C3N4 sheets results in the formation of a P2ABT/g-C3N4 nanocomposite, exhibiting favorable morphological and electrical properties that position it as a promising candidate for a paste utilized in a two-symmetric electrode hydride supercapacitor. The decoration process involves the oxidation of 2-aminobenzene thiol with K2S2O8, leading to the polymer coating of the embedded 2D g-C3N4 materials, yielding a robust composite. Analysis via scanning electron microscopy (SEM) unveils the formation of 2D sheets of g-C3N4 with an average length, width, and thickness of 750 nm, 200 nm, and 15 nm, correspondingly. The composite establishes a sturdy network with a porous structure, indicative of the synergistic combination of the electrical characteristics of the polymer and g-C3N4. In the construction of the two-symmetric electrode supercapacitor, an impressive specific capacitance (CS) of 310 F g−1 is achieved at 0.2 A/g. The supercapacitor exhibits a promising energy density (E) of 26.8 W h kg−1 and maintains retention stability even after undergoing 1000 charge/discharge cycles. Notably, the retention rate remains high at 98% after 250 cycles and 96% after an extended cycling period of 1000 cycles. This exceptional performance positions the supercapacitor as a prospective candidate for applications in industrial settings and within batteries. Its advantages lie in its ease of fabrication, mass production capabilities, and cost-effective manufacturing techniques, opening new avenues for these materials in energy storage fields.
A non-invasive blood glucose detection using a slotted microstrip antenna sensor
Authors: Syamala Neeli , Kumar Bandi Kiran , Raju K Padma
Published: May 2024

A novel highly sensitive and compact slotted microstrip antenna sensor consisting of slots with defected ground structure is designed. The substrate used in the design of antenna is FR-4 of concise dimensions 30 × 30 × 1.6

mm

3

and the developed antenna resonates at 3 GHz. The human finger consisting of several layers namely bone, blood, fat and skin is modelled in the electromagnetic simulation (Computer Simulation Technology) environment resulting in finger phantom. The finger phantom is situated at different locations on proposed antenna for evaluating the concentrations of glucose from 0 to 1000 (mg/dL) and the corresponding shift in frequencies are estimated. For detection of glucose concentration in human blood, the obtained frequency shifts in the proposed work are used. In this proposed work, at the top side of proposed antenna, the finger phantom is situated, an uttermost shift in frequency of 48 MHz, sensitivity of 48 KHz/(mg/dL) and a least possible shift in frequency of 24 MHz, sensitivity of 24 KHz/(mg/dL) are obtained.
Temperature-switchable anti-reflective structure based on vanadium dioxide phase transition in the visible and near-infrared wavelength regions
Authors: Daliran Neda , Hassanzadeh Abdollah
Published: May 2024

Nowadays, the anti-reflective (AR) structures are essential in many applications like display screens, photovoltaic structures and light detection and ranging. Traditionally, the AR surfaces are almost multilayer (ML) structures to minimize the reflection value by producing the destructive interference of reflected light beams at the layers’ interfaces. In the new and advanced AR surfaces, nanostructures (NS) are proposed and used for minimizing the reflection. In this paper, we propose a temperature-switchable AR-ML-NS, based on vanadium dioxide (VO2) phase transition from semiconductor to metallic state around the critical temperature of 68 °C. Here, a pyramidal NS of VO2 is considered on top surface of a ML which minimizes the light reflection of the structure. While some AR structures may work in some restricted light wavelengths, here our proposed structure’s AR wavelength region can be tuned between the visible and near-infrared (NIR) region through the thermal phase transition of VO2. VO2 phase control leads to a temperature-switchable AR structure, which is of great importance for investigating different switchable AR structures.
Superior performance in double-diffused MOSFET by multi-trench gate structure: physical investigation and design
Authors: Shokouhi Shoormasti Ali , Abbasi Abdollah , Orouji Ali A
Published: May 2024

The Double-diffused Metal-Oxide-Semiconductor (D-MOSFET) is the first Power MOSFET structure to be widely used across an extensive range of power levels. This article describes a physical investigation and design of D-MOSFET construction with superior performance. We introduce a groundbreaking exploration into the design of trench gates within U-shaped double-diffused MOSFETs (UDMOSFETs), focusing on Baliga’s figure of merit (BFOM). The findings provide valuable insights for advancing power semiconductor devices, underscoring the importance of trench gate technology in optimizing device performance. The BFOM reaches its peak when the doping concentration of the drift region (NDrift) is 6 × 1016 cm−3 with an indication of almost 40% improvement in MTG-UDMOSFET (M = 4) compared to C-UDMOSFET. Furthermore, within the optimum values of NDrift, length of the drift region, and depth of trench gate, the on-resistance in MTG-UDMOSFET (M = 4) experiences a 46% reduction compared to the conventional structure.
Mechanism of formation and evolution of bound states in the continuum of split-hole all-dielectric metasurface under asymmetric displacement perturbation
Authors: Chen Ying , Zhao Guoting , Li Weiqiang , Cui Dongyan , Shi Moqing , Wang Qinghui
Published: May 2024

Bound states in the continuum (BICs) with ultra-high Q properties have attracted much attention for their perfect localization in the continuous spectral range coexisting with extended waves. In this study, breaking the traditional excitation form of structure breakage or excitation field asymmetry, a monolithic silicon nanodisk array with relative displacement generated by the complete splitting of square nanopores is proposed based on the unique electromagnetic properties of all-dielectric metamaterials. During the introduction of perturbations by asymmetric displacements of splitting holes, it is shown by numerical simulations that two BICs at different wavelengths can be realized. Combined with eigenmodes of group theory, the symmetric matching relationship between the symmetry-protected BICs and the free-space radiation during the evolution process is analytically demonstrated, and the formation mechanism and the evolution law of the BICs excited by this metasurface are deeply investigated. meanwhile, it also provides a theoretical basis for the polarization dependence of quasi-BICs excitation and the ultra-high Q factor expression of BICs. Furthermore, near-field distribution and multipole decomposition show that the field distribution and surface currents support the excitation of BIC-driven toroidal dipole and magnetic quadrupole dual modes. This study not only provides an effective reference for the stability of high-Q resonance wavelengths, but also solves the problem of the lack of universality in analyzing the resonance mechanism based on resonance phenomena, and provides solid theoretical support for the study of displacement-mediated BICs resonance excitation and evolution.
Influence of plasma on the optical appearance of spinning black hole in Kalb-Ramond gravity and its Existence around M87* and Sgr A*
Authors: Raza Muhammad Ali , Zubair M. , Maqsood Eiman
Published: May 2024

The visible universe is filled with different types of plasma media in the form of stars, nebulas and other forms of excited gases. These matter fields have a high influence on the gravity and are likely to be present around the black holes due to the immense gravitational attraction. Since a plasma medium affects the speed of light, therefore we investigated the null geodesics and various optical features around the rotating black hole in Kalb-Ramond gravity immersed in plasma medium. Various plasma distributions are considered to develop a comparative study for their influence on unstable null circular orbits, shadows and evaporation rate of the black hole in the presence of a plasma medium. Moreover, the shadow results are also compared with Event Horizon Telescope data for M78* and Sgr A* in order to estimate the parametric bounds for which the rotating black hole in Kalb-Ramond gravity is considered either M87* or Sgr A* under the different values of plasma parameters. From this analysis, we also found the distribution of plasma that has a significant impact on the above mentioned features and is most likely to be present around M87* and Sgr A*.
Simulation-based inference of deep fields: galaxy population model and redshift distributions
Authors: Moser Beatrice , Kacprzak Tomasz , Fischbacher Silvan , Refregier Alexandre , Grimm Dominic , Tortorelli Luca
Published: May 2024

Accurate redshift calibration is required to obtain unbiased cosmological information from
large-scale galaxy surveys. In a forward modelling approach, the redshift distribution n(z) of
a galaxy sample is measured using a parametric galaxy population model constrained by
observations. We use a model that captures the redshift evolution of the galaxy luminosity
functions, colours, and morphology, for red and blue samples. We constrain this model via
simulation-based inference, using factorized Approximate Bayesian Computation (ABC) at the image
level. We apply this framework to HSC deep field images, complemented with photometric redshifts
from COSMOS2020. The simulated telescope images include realistic observational and instrumental
effects. By applying the same processing and selection to real data and simulations, we obtain a
sample of n(z) distributions from the ABC posterior. The photometric properties of the simulated
galaxies are in good agreement with those from the real data, including magnitude, colour and
redshift joint distributions. We compare the posterior n(z) from our simulations to the
COSMOS2020 redshift distributions obtained via template fitting photometric data spanning the
wavelength range from UV to IR. We mitigate sample variance in COSMOS by applying a reweighting
technique. We thus obtain a good agreement between the simulated and observed redshift
distributions, with a difference in the mean at the 1σ level up to a magnitude
of 24 in the i band. We discuss how our forward model can be applied to current and future
surveys and be further extended. The ABC posterior and further material will be made publicly
available at https://cosmology.ethz.ch/research/software-lab/ufig.html.
Particle content of very inclined air showers for radio signal modeling
Authors: Guelfand Marion , Chiche Simon , Kotera Kumiko , Prunet Simon , Pierog Tanguy
Published: May 2024

The reconstruction of very inclined air showers is a new challenge for next-generation radio experiments such as the AugerPrime radio upgrade, BEACON, and GRAND, which focus on the detection of ultra high energy particles. To tackle this, we study the electromagnetic particle content of very inclined air showers, which has scarcely been studied so far. Using the simulation tools CORSIKA and CoREAS, and analytical modeling, we explore the energy range of the particles that contribute most to the radio emission, quantify their lateral extent, and estimate the atmospheric depth at which the radio emission is strongest. We find that the spatial distribution of the electromagnetic component in very inclined air showers has characteristic features that could lead to clear signatures in the radio signal, and hence impact the reconstruction strategies of next-generation radio-detection experiments.
Neutron stars in scalar torsion theories with non minimal coupling
Authors: Kehal Youcef , Nouicer Khireddine , Boumaza Hamza
Published: May 2024

We explore the existence and configurations of static and slowly rotating neutron stars (NSs) within a specific truncation of teleparallel scalar torsion theory. In this model, a scalar field ϕ is non-minimally coupled to the torsion scalar as ξTϕ
2, in the presence of the scalar potential V(ϕ) = -μ
2
ϕ
2/2 + λϕ
4/4. We establish the hydrostatic equilibrium equations for the static scenario and numerically solve them for both interior and exterior regions, employing appropriate boundary conditions near the center and at a distant location far away from the star's surface. Radial profiles of metric functions and the scalar field, alongside mass-radius diagrams, are plotted, utilizing four different realistic equations of state (EOS). Our results align closely with observational constraints from the GW170817 event, revealing a maximal mass of 2.37 M
⊙ achieved with the BSk21 EOS for a coupling parameter ξ = 0.25. Extending our analysis to encompass slow rotation, we establish the relationship between the star's moment of inertia and its mass. Furthermore, we explore future observations of NSs utilizing the redshift surface observable. Finally, we demonstrate the validity of the universality relation between the two forms of normalized moment of inertia within teleparallel scalar torsion theory with non minimal coupling.
Sound classification with time-frequency features in forest environment
Authors: Xu Sizhe , Chen Yang
Published: May 2024

The study of forest sound classification has drawn more attention recently due to its potential for illegal activities and natural disaster monitoring. Based on the forest sound classification dataset (FSC22), a dataset specific to possible sound existing in the forest, five classification methods are utilized to investigate the relationship between recognition accuracy and the number of sound acoustic features, as well as the number of target classes. The results confirmed that extreme random forest is the best method for forest sound classification, with an accuracy of around 70% when the target class number is above 20. Further, Mel-frequency cepstral coefficients are the critical feature for sound classification, while fuzzy labels in the dataset may reduce the success rate of recognition.
Sound absorption model of thin woven fabric with tortuosity effects by equivalent circuit method
Authors: Tang Xiaoning , Zhu Shubing
Published: May 2024

The fabric has been widely used as a noise-reduction material. This paper presents a revised equivalent circuit model to simulate the acoustical behavior of woven fabric with backing an air gap, with a special focus on including a tortuosity parameter. The simulated sound absorption of three fabrics with and without the tortuosity parameter was experimentally validated. The equivalent circuit model including the tortuosity parameter predicts the absorption curve better, particularly at the local minima in comparison to the existing models without the tortuosity effects. It is beneficial to the structural design of woven fabric with enhanced sound absorption.
Numerical study of the behavior of a near-wall bubble under the influence of an acoustic wave
Authors: Tian Lei , Zhang Yongxue
Published: May 2024

Acoustic cavitation has been applied to many ultrasonic fields, but its characteristics are not fully understood, especially near the wall. To analyze the dynamics of a near-wall acoustic bubble, an acoustic pressure wave boundary condition is developed in the OpenFOAM platform. We first conducted the model’s validation with an experiment to prove its accuracy. The bubble’s radius increases when the bubble is excited by the lower-pressure wave, and it decreases under the higher-pressure wave. When the bubble collapses, its pressure and temperature will reach the maximum value. In accordance with the non-dimensional distance, the dynamics of the acoustic-driven bubble are classified into three types, i.e., the liquid jet not touching the nearby wall, the liquid jet touching the wall, and no obvious liquid jet. The maximum value of pressure and temperature increases with the dimensionless distance decreasing if the dimensionless distance is small. However, there is no variation of these peak values with dimensionless distance if the dimensionless distance is large.
Study on adjustable low-frequency sound absorbers based on digital shunt loudspeakers
Authors: Xu Yubing , Cong Chaonan
Published: May 2024

Low-frequency noise is a critical frequency band that affects people’s physical and mental health. Traditional sound absorption technology is limited in effectiveness at low frequencies due to spatial constraints. Shunt loudspeakers, which consist of a loudspeaker connected to a shunt circuit, have emerged as a rapidly developing solution for low-frequency noise control. However, most shunt circuits are implemented using analog circuits, resulting in poor stability and accuracy due to the presence of parasitic resistance. As a result of this situation, this paper proposes an adjustable low-frequency sound absorber based on digital shunt loudspeakers, where the shunt circuit is realized through digital synthetic impedance based on FPGA technology. Additionally, the acoustic impedance can be easily adjusted by the digital shunt circuit without relying on cavity depth adjustments. Experimental results validate that the proposed sound absorber offers excellent performance in adjustable low-frequency sound absorption, thus confirming its theoretical basis.
Ultrasonic cavitation noise extraction based on fence sampling
Authors: Wu Boyue , Tong Haoyang , Chen Yi , Zhao Han
Published: May 2024

The composition of the ultrasonic cavitation sound field is complex, including fundamental, harmonic, subharmonic, super-harmonic, and broadband transient noise. Fundamental waves, harmonics, etc., may interfere with the analysis and research of broadband transient cavitation noise, so it is necessary to filter out these interferences in the sound field. This article conducts measurement experiments on the ultrasonic cavitation sound field generated by high-power ultrasonic cleaning transducers. By utilizing the characteristics of the fence effect, the acoustic signal in the ultrasonic cavitation sound field is resampled through fence sampling so that the fundamental and harmonic components are fused at 0 Hz and filtered out. The ultrasonic cavitation noise is successfully extracted, and its signal structure is the same as the noise component structure in the original signal.
Investigation of dynamic characteristics of hydrofoil with leading-edge tubercles
Authors: Fan Menghao , Sun Zhaocheng , Yu Ran , Li Zengliang
Published: May 2024

The convex structure of a humpback whale flipper is included in the airfoil design to investigate the control principle of the dynamic stall process. The effect of two different types of tubercles on the dynamic stall process of airfoils was investigated. The distribution of dynamic hysteresis loops and pressure fields with streamlines was used to explain the properties of the dynamic flow field and the emergence of dynamic stall vortices. The results demonstrate that the airfoils with tubercles have stronger hysteretic characteristics in the pre-stall region, and the ζ
CM of mod-1 is increased by 51.33%, indicating stronger torsional hydroelastic stability. In the post-stall region, mod-2 is always in a condition of significant flow separation, which impairs the torsional hydrodynamic stability of the airfoil and has the potential to cause flutter. These findings suggest that leading-edge tubercles offer a negligible advantage in reducing airfoil dynamic stall, and their significance warrants further investigation.
Numerical simulation of ice loading characteristics of ships in a wave-current environment in a broken ice area
Authors: Sun Rui , Li Zhifu , Shi Yuyun
Published: May 2024

A numerical simulation technique with CFD-DEM coupling is used to simulate a full-scale KCS model sailing in the pancake ice region. Based on the actual polar information, the Stokes fifth-order wave model is selected. The pancake ice particle of two scales is established based on the DEM, and the corresponding broken-ice region is generated. The contact and collision problems of ice-ice and ice-wall (ship) were analyzed by solving the Hertz-Mindlin model, and the monitored data were processed and summarized. The results show that the ice load on the ship is a repetitive “loading-unloading” process, and the peak ice load curve is characterized by segmented and concentrated fluctuations. In terms of ice parameters, the pancake diameter has a great degree of influence on the crushed ice loads, and the size of the crushed ice loads increases with the diameter of the crushed ice particles.
Calculation and analysis of the transition process of a Francis turbine in a power plant
Authors: Yuan Yang
Published: May 2024

This paper introduces the calculation method and results of the large-fluctuation transition process of the Francis hydro-generator set. The operation of the power station shows that the calculation method and results can meet the engineering requirements, but they cannot reflect the state of the unit during small fluctuations. For large-scale units, this problem needs to be addressed and further research.
Study on two-phase displacement law considering mass transfer and diffusion
Authors: Zhang Lei , Li Aoyang , Sun Hai , Jing Wenlong
Published: May 2024

The influence of channeling on viscous fingering instability of CO2 miscible displacement is studied in the paper. Due to the viscous fingering not easily observed in porous media, channeling is used to simplify the viscous fingering instability. We adopted nonlinear simulation to investigate the development of viscous fingering instability during the displacement of Newtonian fluids in a channel by miscible fluids, and the influence of different Pe and different viscosity ratio R was studied. Under homogeneous conditions, when R is the same, the larger the Pe is, the more obvious the convection in the process of CO2 displacement is, the earlier the viscous fingering occurs, and the shorter the time for the finger to break through to the right boundary is. When Pe is the same, the larger the R is, the more unstable the contact area of miscible displacement becomes. More finger structures appear, and more complex fingering phenomena occur. The larger the R is, the earlier the fingering phenomenon appears, and the earlier it breaks through to the right boundary. In addition, we studied the change in Relative Mixing Length (RML) during the diffusion process quantitatively. Finally, our investigation delved into the impact of heterogeneity on viscous fingering. We observed that under significant heterogeneity, viscous fingering tends to manifest preferentially in the direction of increasing permeability.
Aggregate scheduling potential evaluation of large-scale air conditioning loads
Authors: Huang Hui , Gao Yun , Wang Song , Li Shun , Wu Fuzhang , Zhu Bin , Long Yi
Published: May 2024

As an adjustable load, the air conditioning (AC) load is a high-quality resource for power system operation regulation. However, due to the large number of AC loads and the heterogeneity among individual users, the scheduling potential of AC loads is difficult to accurately calculate. An aggregate scheduling potential evaluation of large-scale AC loads is proposed. Firstly, according to the operation characteristics of ACs, the aggregation models of central ACs and household split-type ACs are constructed by using the equivalent thermal parameter model and Monte Carlo sampling method respectively. Secondly, based on the proposed aggregation models of large-scale AC loads, the AC loads are rescheduled by resetting the set temperature, and the scheduling potential calculation model of central ACs and residential ACs is obtained. Finally, case studies show that AC loads have considerable scheduling potential when the indoor temperature is maintained within the range of human comfort.
Selection and integration of adjustable load in multiple scenarios
Authors: Zhou Zhaozheng , Ye Wei , Leng Zhenglong
Published: May 2024

In the context of the “carbon peaking and carbon neutrality goals”, the new electricity systems are evolving towards source-load friendly interactions. At the same time, the increasing necessity for adjustable loads to participate in the power balance of the new electricity systems is highlighted. Consequently, a large-scale source-grid-load design scheme is proposed. It employs three independent communication channels to facilitate communication between users and intelligent grid-load terminals. Based on analysis of the individual loads and equipment characteristics of each user, principles for user shunt load access principle and adjustable loads are formulated by combining the maximum duration, frequency constraints, and compliance costs. Furthermore, it proposes construction plans for both the customer side in a single distribution room and the customer side distributed across different locations. According to the experimental analysis of 245 users, the response time of the experimental system is less than 600 ms. These advancements enhance the emergency response speed and responsiveness, contributing to the advancement of precise, real-time, and lean management of the demand side of the power grid.
Study on the error characteristics of transformer for primary and secondary fusion used in pole-mounted switchgear
Authors: Xia Lingyu , Wu Xixiu , Hou Hui , Wu Shipu , Peng Yunbing , Cao Jiaxin
Published: May 2024

The fusion of primary and secondary functions refers to integrating the function of primary equipment and secondary equipment together. If doing so, the working condition of the equipment for primary and secondary fusion becomes more and more complex and bad, especially the transformer working in the smaller workspace after fusing. Therefore, this paper focuses on the transformer used in primary and secondary fusion pole-mounted Switchgear and establishes the temperature field and electric field simulation model of the primary and secondary fusion pole-mounted switchgear transformer, respectively, and the temperature rise and the environment electric field interference influencing the error of transformer are analyzed as well. When the working environment temperature ranges from -40 to 70°C, the maximum error of low-power current transformers and resistive voltage transformers is 0.1246% and 0.0371%, respectively. The electric field is one of the main factors influencing resistive voltage transformers, which makes ratio errors and angle errors -0.256% and -22.5392’, respectively. The research reveals that under conditions, the error is mainly dependent on temperature rise and electric field. These two factors have a great influence on the error, while the transformers still have enough reliability.
A method of distributed series compensation for low voltage management in power distribution network
Authors: Zhao Zhiyu , Wang Yajuan , Liang Weichen , Jiang Xin , Liu Bo , Ma Xinsheng , Li Xuan
Published: May 2024

In some areas with sparse populations and dispersed power loads, the construction investment of distribution network lines cannot keep up, and the phenomenon of low voltage at the end of the power distribution network is particularly serious, even causing some household appliances to be unable to start. This article aims to provide some solutions to alleviate the low voltage of distribution network lines in certain regions. It introduces a method based on distributed series compensation for long lines with low voltage of the line terminal. In the same distribution network line, it is installed two or more sets of series compensators to alleviate the low voltage problem at the end of the long line of the distribution network based on a decentralized arrangement. The technical scheme is based on a 10 kV feeder for simulation to verify the correctness and effectiveness of the proposed method.
Data-driven battery health state estimation based on charging and switching cabinets
Authors: Zhang Yong , Liu Jingwei , Zhen Jiuguo , Qiao Zhenjia
Published: May 2024

Accurate evaluation of the battery’s state of health (SOH) in the charging and switching cabinet is crucial to ensure the battery operates safely and reliably, while also reducing maintenance costs for the battery system. A support vector regression technique, utilising the sparrow algorithm optimisation, is suggested to improve the precision of assessing the battery’s state of health in the charging and switching cabinet. This algorithm tackles the task of identifying parameters in the conventional model. Analysing the ageing dataset of lithium batteries is the initial stage to determine the health parameters that signal the battery’s health state. The support vector machine regression algorithm is employed to select the kernel function and penalty factor, which are fine-tuned using the sparrow optimisation technique. The data is utilised to create the SSA-SVR model. The battery health status of the charging and switching cabinet is assessed. The study shows that the enhanced support vector regression model can effectively monitor the status of lithium-ion batteries and achieve superior estimation results for different types of batteries.
Prediction of power generation output of compressed air energy storage tank based on temperature limitation
Authors: Wen Xiankui , Wu Yinghao , Zhang Junwei , Zhang Shihai , Wu Chao
Published: May 2024

The pressure and temperature of the CAES system drop during the power generation process. This generation will be forced to stop when the temperature reaches the metal material limit. To avert the power generation process from stopping due to the temperature dropping too low, it is necessary to monitor and predict the power output of the CAES system in real time. By setting the relevant control operation logic, according to the temperature limit value of the gas canister, the minimum allowable temperature of the gas canister design, and the maximum value of the minimum allowable temperature of the pipe design between the gas canister and the heat exchanger, the minimum allowable temperature of the gas canister is obtained. the residual energy release energy and residual energy release time of the gas storage tank can be calculated by collecting relevant parameters in real time. It is verified by the simulation experiment of the 10 MW CAES system model. By monitoring the changes in parameters such as the temperature of the gas canister during the energy release process, the prediction model can calculate the compressed gas in the gas canister more accurately, and the power generation output can be predicted in the operation of the CASE system. Mastering the residual energy release energy and residual energy release time of the gas canister can arrange the operation mode in advance and improve the reliability of unit operation.
Direct power control of dual three-phase permanent magnet synchronous motor based on multiple vectors
Authors: Pei Yuanxin , Zhi Pengfei , Wei Haifeng , Zhang Yi
Published: May 2024

In response to the traditional mode of dual three-phase permanent magnet synchronous generator switch form vector direct power control (DPC), the current harmonics are large, the active (P) and reactive (Q) harmonic oscillations are large, and the unstable losses of each phase current are large. A virtual voltage vector direct power control method based on duty cycle modulation is proposed. This method compares and synthesizes the two vectors of the outermost and second layers of the PWM rectifier, as well as three large vector synthesis methods, to obtain 12 new virtual voltage vectors. Then, the combined voltage vector is directly modulated into the deadbeat switching table, and the optimal predicted vector value is calculated based on the principle of the deadbeat formula, further suppressing the problem of large fluctuations in active and reactive power. Results show that the proposed multi-vector composite odd even quadrant DPC can effectively reduce current harmonics and power ripple, make the phase current more stable, reduce motor operating losses, and significantly improve the motor.
LLC resonant converter analysis in PO mode
Authors: Mao Wenlong , Ma Xiaosan
Published: May 2024

The PO mode under time-domain analysis is a kind of discontinuous conduction mode (DCM) which is beneficial to reduce the switching loss of the converter, but the calculation of the gain and frequency characteristics of the converter in this mode is cumbersome and difficult to be solved. Based on the analysis method of time domain approximation, the PO operating mode characteristics of the LLC resonant converter are analyzed, and a simple and accurate voltage gain calculation formula is theoretically deduced. Simple analytical expressions for the PO mode power boundary conditions are given based on the voltage variations of the magnetizing inductance and capacitance. A simulation model of the studied converter is established, and the simulation can prove that the proposed voltage gain formula and PO mode boundary conditions are correct.
Shore Power System Load Forecasting Model based on IDBO algorithm and PCA-BiLSTM Network
Authors: Gu Shuangnan , Yang Yayu , Shi Wenchao , Tong Jijian
Published: May 2024

Shore power offers convenient and sustainable power services to ships docking in ports, playing a pivotal role in advancing environmental preservation and the effective utilization of resources. Shore power system loads are susceptible to numerous influencing factors. Therefore, it is crucial to identify a highly accurate load forecasting model to facilitate the judicious allocation of power resources. A short-term shore power system load forecasting model based on the improved dung beetle optimization algorithm (IDBO) and principal component analysis (PCA) in conjunction with the enhanced bidirectional long and short-term memory (BiLSTM) network is proposed in this paper. The IDBO algorithm improves the problem of low convergence accuracy and vulnerability to local optima in DBO. This is achieved by population initialization based on cubic chaotic mapping, amalgamating walrus optimization algorithm, and adaptive t-distribution perturbation strategy. The performance of the BiLSTM, IDBO-BiLSTM, and PCA-IDBO-BiLSTM shore power system load forecasting models are compared through case studies, revealing that the proposed PCA-IDBO-BiLSTM model demonstrates superior predictive capabilities.
A novel approach for disentangling packed peaks in the energy spectrum of γ detector arrays through γ-γ coincidence analysis
Authors: Xu Yingfeng , Wang Shitao
Published: May 2024

A novel approach has been proposed to effectively separate cascaded and closely packed full energy peaks in the energy spectrum of γ detector arrays. By conducting a sequence of γ-γ coincidence analyses on the energy spectrum, it is feasible to obtain a spectrum that represents the product of these packed peaks. We have designated the newly obtained spectrum as the “product spectrum”. The energy spectrum and the newly obtained product spectrum can be simultaneously fitted, enabling a more precise fitting and separation of the closely packed peaks. This method has been mathematically proven, and validated through the use of Monte Carlo simulation. The systematic errors of this method are also taken into consideration.
Modelling future coastal water pollution: impacts of point sources, socio-economic developments & multiple pollutants
Authors: Bak Mirjam P , Kroeze Carolien , Janssen Annette B G , Strokal Maryna
Published: May 2024

Urbanisation is happening worldwide. In 2100, over 70% of the population is projected to live in highly urbanised areas. As a result, urban wastewater discharge may increase. This may add multiple pollutants to rivers and coastal waters. However, current knowledge on how urbanisation-related socio-economic developments affect coastal water pollution is limited. In this study, we analysed individual and combined impacts of wastewater treatment improvements, economic growth and city expansion on future coastal water pollution from point sources (sewage and open defecation) by sub-basin taking a multi-pollutant approach. We improved the existing MARINA-Multi model (version Global-1.0) by integrating hydrology and pollutant retentions in order to quantify river exports of total dissolved nitrogen, total dissolved phosphorus, microplastics and triclosan to coastal waters for 2010 and 2100 using scenario analysis. Globally, river exports from point sources are projected to more than double by 2100 for all pollutants, especially in Africa and Asia. Wastewater treatment improvements, economic growth and city expansion can have a positive (less pollution) or negative (more pollution) impact on future coastal water pollution. These impacts differ among pollutants and sub-basins. Wastewater treatment improvements may globally reduce multi-pollutant issues (−30% to −38% change on average) compared to the reference scenario (positive impact). Economic growth and city expansion may globally enhance multi-pollutant issues (+15% to +25% and +28% to +33% change on average, respectively) compared to the reference scenario (negative impact). A combined scenario, accounting for all three socio-economic developments simultaneously, may globally reduce or enhance pollutant issues (−21% to +50% change on average) compared to the reference scenario. In the combined scenario, the reinforcements of positive and negative impacts are pollutant- and region-dependent. Our study gives insights into future coastal water pollution, which aids in identifying management strategies for urban areas, hence contributing to reaching Sustainable Development Goal 14.
Coated boron layers by boronization and a real-time boron coating using an impurity powder dropper in the LHD
Authors: ASHIKAWA Naoko , LUNSFORD Robert , NESPOLI Federico , GILSON Erik , YU Yaowei , HU Jiansheng , KADO Shinichiro
Published: May 2024

In the Large Helical Device (LHD), diborane (B2H6) is used as a standard boron source for boronization, which is assisted by helium glow discharges. In 2019, a new Impurity Powder Dropper (IPD) system was installed and is under evaluation as a real-time wall conditioning technique. In the LHD, which is a large-sized heliotron device, an additional helium (He) glow discharge cleaning (GDC) after boronization was operated for a reduction in hydrogen recycling from the coated boron layers. This operational time of 3 h was determined by spectroscopic data during glow discharges. A flat hydrogen profile is obtained on the top surface of the coated boron on the specimen exposed to boronization. The results suggest a reduction in hydrogen at the top surface by He-GDC. Trapped oxygen in coated boron was obtained by boronization, and the coated boron, which has boron-oxide, on the first wall by B-IPD was also shown. Considering the difference in coating areas between B2H6 boronization and B-IPD operation, it would be most effective to use the IPD and B2H6 boronization coating together for optimized wall conditioning.
Mode analysis of spin field of thermal atomic ensembles
Authors: Wang Weiyi , Xia Mingming , Quan Wei , Wei Kai
Published: May 2024

The spin dynamics in a thermal atomic vapor cell have been investigated thoroughly over the past decades and have proven to be successful in quantum metrology and memory owing to their long coherent time and manipulation convenience. The existing mean field analysis of spin dynamics among the whole cell is sometimes inaccurate due to the non-uniformity of the ensemble and spatial coupling of multi-physical fields interacting with the ensembles. Here we perform mode analysis onto the quasi-continuous spin field including atomic thermal motion to derive Bloch mode equations and obtain corresponding analytical solutions in diffusion regime. We demonstrate that the widely used mean field dynamics of thermal gas is a particular case in our solution, corresponding to the uniform spatial mode. This mode analysis approach offers a precise method for analyzing the dynamics of the spin ensemble in greater detail from a field perspective, enabling the effective determination of spatially non-uniform multi-physical fields coupling with the spin ensembles, which cannot be accurately analyzed by the mean field method. Furthermore, this work paves the way to address quantum noises and relaxation mechanisms associated with non-uniform fields and inter-atomic interactions, which limit further improvement of ultra-sensitive spin-based sensors.
Novel fabrication techniques for ultra-thin silicon based flexible electronics
Authors: Lee Ju Young , Ju Jeong Eun , Lee Chanwoo , Won Sang Min , Yu Ki Jun
Published: May 2024

Flexible electronics offer a multitude of advantages, such as flexibility, lightweight property, portability, and high durability. These unique properties allow for seamless applications to curved and soft surfaces, leading to extensive utilization across a wide range of fields in consumer electronics. These applications, for example, span integrated circuits, solar cells, batteries, wearable devices, bio-implants, soft robotics, and biomimetic applications. Recently, flexible electronic devices have been developed using a variety of materials such as organic, carbon-based, and inorganic semiconducting materials. Silicon (Si) owing to its mature fabrication process, excellent electrical, optical, thermal properties, and cost efficiency, remains a compelling material choice for flexible electronics. Consequently, the research on ultra-thin Si in the context of flexible electronics is studied rigorously nowadays. The thinning of Si is crucially important for flexible electronics as it reduces its bending stiffness and the resultant bending strain, thereby enhancing flexibility while preserving its exceptional properties. This review provides a comprehensive overview of the recent efforts in the fabrication techniques for forming ultra-thin Si using top-down and bottom-up approaches and explores their utilization in flexible electronics and their applications.