bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation of collisional among multi-soliton, multi-singular solition and rogue wave around the critical values in an unmagetized plasma
Authors: Akter Shahrina , Hafez M G , Sakthivel R
Published: February 2024

Progress in understanding the propagation characteristics of (i) collisional acoustic among multi-soliton and multi-singular soliton around the critical values and their corresponding phase shifts and (ii) collision between two rogue waves (RWs) propagating toward each in a plasma environment is presented. The considered plasma environment consists of mobile cold positrons, immobile positive ions and (r, q)-distributed hot positrons, and electrons. To accomplish our goal, the coupled modified Korteweg–de Vries equations (mKdVEs) and nonlinear Schrödinger equations (NLSEs) are derived from the considered plasma environment. Based on the concept of Hirota's bilinear method, the multi-soliton and multi-singular soliton solutions of the coupled mKdVEs are determined directly. In addition, the analytical unstable RWs solutions of the coupled NLSEs are determined. With the impact of physical parameters, (i) the trajectories are described for double, triple, quadruple and quintuple positron acoustic bi-directional multi-soliton and (ii) the variation of collisional RWs profiles are displayed with physical interpretation. The results described by the coupled mKdVEs also show that the scattered double-, triple-, quadruple-, and quintuple-soliton are elastic and preserved their original features oppositely after the collision around the critical value of any specific plasma parameter.
Coulomb-assisted nonlocal electron transport between two pairs of Majorana bound states in a superconducting island
Authors: Wang 王 Hao-Di 浩迪 , Ren 任 Jun-Tong 俊潼 , Lü 吕 Hai-Feng 海峰 , Ke 柯 Sha-Sha 莎莎
Published: February 2024

We investigate the nonlocal transport modulated by Coulomb interactions in devices comprising two interacting Majorana wires, where both nanowires are in proximity to a mesoscopic superconducting (SC) island. Each Majorana bound state (MBS) is coupled to one lead via a quantum dot with resonant levels. In this device, the nonlocal correlations can be induced in the absence of Majorana energy splitting. We find that the negative differential conductance and giant current noise cross correlation could be induced, due to the interplay between nonlocality of MBSs and dynamical Coulomb blockade effect. This feature may provide a signature for the existence of the MBSs.
Influence of substrate effect on near-field radiative modulator based on biaxial hyperbolic materials
Authors: Liu 刘 Ruiyi 睿一 , Liu 刘 Haotuo 皓佗 , Hu 胡 Yang 杨 , Cui 崔 Zheng 峥 , Wu 吴 Xiaohu 小虎
Published: February 2024

Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer (NFRHT) in anisotropic media. Due to the strong in-plane anisotropy, natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects. However, in practical applications, natural hyperbolic materials need to be deposited on the substrate, and the influence of substrate on modulation effect has not been studied yet. In this work, we investigate the influence of substrate effect on near-field radiative modulator based on α-MoO3. The results show that compared to the situation without a substrate, the presence of both lossless and lossy substrate will reduce the modulation contrast (MC) for different film thicknesses. When the real or imaginary component of the substrate permittivity increases, the mismatch of hyperbolic phonon polaritons (HPPs) weakens, resulting in a reduction in MC. By reducing the real and imaginary components of substrate permittivity, the MC can be significantly improved, reaching 4.64 for ε
s = 3 at t = 10 nm. This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect, and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.
Quantum correlations and entanglement in coupled optomechanical resonators with photon hopping via Gaussian interferometric power analysis
Authors: Lahlou Y. , Maroufi B. , Daoud M.
Published: February 2024

Quantum correlations that surpass entanglement are of great importance in the realms of quantum information processing and quantum computation. Essentially, for quantum systems prepared in pure states, it is difficult to differentiate between quantum entanglement and quantum correlation. Nonetheless, this indistinguishability is no longer holds for mixed states. To contribute to a better understanding of this differentiation, we have explored a simple model for both generating and measuring these quantum correlations. Our study concerns two macroscopic mechanical resonators placed in separate Fabry–Pérot cavities, coupled through the photon hopping process. this system offers a comprehensively way to investigate and quantify quantum correlations beyond entanglement between these mechanical modes. The key ingredient in analyzing quantum correlation in this system is the global covariance matrix. It forms the basis for computing two essential metrics: the logarithmic negativity (

E
N
m

) and the Gaussian interferometric power (

P
G
m

). These metrics provide the tools to measure the degree of quantum entanglement and quantum correlations, respectively. Our study reveals that the Gaussian interferometric power (

P
G
m

) proves to be a more suitable metric for characterizing quantum correlations among the mechanical modes in an optomechanical quantum system, particularly in scenarios featuring resilient photon hopping.
Extending microwave-frequency electric-field detection through single transmission peak method
Authors: Liu 刘 Qing 青 , Chen 陈 Jin-Zhan 进湛 , Wang 王 He 赫 , Zhang 张 Jie 杰 , Ruan 阮 Wei-Min 伟民 , Wu 伍 Guo-Zhu 国柱 , Zheng 郑 Shun-Yuan 顺元 , Luo 罗 Jing-Ting 景庭 , Song 宋 Zhen-Fei 振飞
Published: February 2024

The strength of microwave (MW) electric field can be observed with high precision by using the standard electromagnetically induced transparency and Aulter–Towns (EIT-AT) technique, when its frequency is resonant or nearly-resonant with the Rydberg transition frequency. As the detuning of MW field increases, one of the transmission peaks (single peak) is easier to measure due to its increased amplitude. It can be found that the central symmetry point of the two transmission peaks f
1/2 is only related to the detuning of MW field Δ
MW and central symmetry point f
0 of resonant MW field, satisfying the relation f
1/2 = Δ
MW/2 + f
0. Thus, we demonstrate a single transmission peak method that the MW E-field can be determined by interval between the position of single peak and f
1/2. We use this method to measure continuous frequencies in a band from −200 MHz to 200 MHz of the MW field. The experimental results and theoretical analysis are presented to describe the effectiveness of this method. For 50 MHz < Δ
MW < 200 MHz, this method solves the problem that the AT splitting cannot be measured by using the standard EIT-AT techniques or multiple atomic-level Rydberg atom schemes.
Structure, ferroelectric, and enhanced fatigue properties of sol–gel-processed new Bi-based perovskite thin films of Bi(Cu1/2Ti1/2)O3–PbTiO3
Authors: Song 宋 Wei-Bin 伟宾 , Xi 席 Guo-Qiang 国强 , Pan 潘 Zhao 昭 , Liu 刘 Jin 锦 , Ye 叶 Xu-Bin 旭斌 , Liu 刘 Zhe-Hong 哲宏 , Wang 王 Xiao 潇 , Shan 单 Peng-Fei 鹏飞 , Zhang 张 Lin-Xing 林兴 , Lu 鲁 Nian-Peng 年鹏 , Fan 樊 Long-Long 龙龙 , Qin 秦 Xiao-Mei 晓梅 , Long 龙 You-Wen 有文
Published: February 2024

Bi-based perovskite ferroelectric thin films have wide applications in electronic devices due to their excellent ferroelectric properties. New Bi-based perovskite thin films Bi(Cu1/2Ti1/2)O3–PbTiO3 (BCT–PT) are deposited on Pt(111)/Ti/SiO2/Si substrates in the present study by the traditional sol–gel method. Their structures and related ferroelectric and fatigue characteristics are studied in-depth. The BCT–PT thin films exhibit good crystallization within the phase-pure perovskite structure, besides, they have a predominant (100) orientation together with a dense and homogeneous microstructure. The remnant polarization (2P
r) values at 30 μC/cm2 and 16 μC/cm2 are observed in 0.1BCT–0.9PT and 0.2BCT–0.8PT thin films, respectively. More intriguingly, although the polarization values are not so high, 0.2BCT–0.8PT thin films show outstanding polarization fatigue properties, with a high switchable polarization of 93.6% of the starting values after 108 cycles, indicating promising applications in ferroelectric memories.
Structure and superconducting properties of Ru1–x
Mo
x
(x = 0.1–0.9) alloys
Authors: Fu 付 Yang 阳 , Gong 龚 Chunsheng 春生 , Tu 涂 Zhijun 志俊 , Tian 田 Shangjie 尚杰 , Wang 王 Shouguo 守国 , Lei 雷 Hechang 和畅
Published: February 2024

We report the detailed crystal structures and physical properties of Ru1−x
Mo
x
alloys in the solid solution range of x = 0.1–0.9. Structure characterizations indicate that the crystal structure changes from the hcp-Mg-type, to β-CrFe-type, and then bcc-W-type. The measurements of physical properties show that the Ru1−x
Mo
x
samples with x ≥ 0.2 are superconductors and the superconducting transition temperature T
c as a function of Mo content exhibits a dome-like behavior.
Enhanced superelasticity and reversible elastocaloric effect in nano-grained NiTi alloys with low stress hysteresis
Authors: Zhou 周 Min 敏 , Wang 王 Wei 维 , Su 苏 Haojian 浩健 , Hu 胡 Zhongjun 忠军 , Li 李 Laifeng 来风
Published: February 2024

Solid-state cooling technologies have been considered as potential alternatives for vapor compression cooling systems. The search for refrigeration materials displaying a unique combination of pronounced caloric effect, low hysteresis, and high reversibility on phase transformation was very active in recent years. Here, we achieved increase in the elastocaloric reversibility and decrease in the friction dissipation of martensite transformations in the superelastic nano-grained NiTi alloys obtained by cold rolling and annealing treatment, with very low stress hysteresis (6.3 MPa) under a large applied strain (5%). Large adiabatic temperature changes (ΔT
max = 16.3 K at ε = 5%) and moderate COPmater values (maximum COPmater = 11.8 at ε = 2%) were achieved. The present nano-grained NiTi alloys exhibited great potential for applications as a highly efficient elastocaloric material.
Efficient parameter inference for gravitational wave signals in the presence of transient noises using temporal and time-spectral fusion normalizing flow*
Authors: Sun 孙 Tian-Yang 天阳 , Xiong 熊 Chun-Yu 春雨 , Jin 金 Shang-Jie 上捷 , Wang 王 Yu-Xin 钰鑫 , Zhang 张 Jing-Fei 敬飞 , Zhang 张 Xin 鑫
Published: February 2024

Glitches represent a category of non-Gaussian and transient noise that frequently intersects with gravitational wave (GW) signals, thereby exerting a notable impact on the processing of GW data. The inference of GW parameters, crucial for GW astronomy research, is particularly susceptible to such interference. In this study, we pioneer the utilization of a temporal and time-spectral fusion normalizing flow for likelihood-free inference of GW parameters, seamlessly integrating the high temporal resolution of the time domain with the frequency separation characteristics of both time and frequency domains. Remarkably, our findings indicate that the accuracy of this inference method is comparable to that of traditional non-glitch sampling techniques. Furthermore, our approach exhibits a greater efficiency, boasting processing times on the order of milliseconds. In conclusion, the application of a normalizing flow emerges as pivotal in handling GW signals affected by transient noises, offering a promising avenue for enhancing the field of GW astronomy research.
First-principle based predictions of the effects of negative triangularity on DTT scenarios
Authors: Mariani A. , Balestri A. , Mantica P. , Merlo G. , Ambrosino R. , Balbinot L. , Brioschi D. , Casiraghi I. , Castaldo A. , Frassinetti L. , Fusco V. , Innocente P. , Sauter O. , Vlad G.
Published: February 2024

Plasmas with negative triangularity (NT) shape have been recently shown to be able to achieve H-mode levels of confinement in L-mode, avoiding detrimental edge localised modes. Therefore, this plasma geometry is now studied as a possible viable option for a future fusion reactor. Within this framework, an NT option is under investigation for the full power scenario of the Divertor Tokamak Test (DTT) facility, under construction in Italy, with

δ

t
o
p

=
−
0.32

/

δ

b
o
t
t
o
m

≃
0.02

top/bottom triangularity values at the separatrix. The transport properties of this scenario are studied in this work. Gyrokinetic GENE simulations and integrated modelling using ASTRA with the quasi-linear trapped gyro-Landau fluid (TGLF) model have been performed. The emerging picture from the ASTRA-TGLF runs with boundary conditions at

ρ

t
o
r

=
0.94

is that, in the L-mode NT option, the larger peaking of the kinetic profiles in the edge region is not sufficient to recover the loss of the PT H-mode pedestal, and reach similar central temperature values. Two additional shapes are also considered, obtained by flipping the triangularity of the scenarios, to single out the effect of the triangularity sign. A negligible ‘direct’ effect of the triangularity is found for the L-mode, while a small beneficial effect is observed for the H-mode. The ASTRA-TGLF results are validated by GENE and TGLF stand-alone at two selected radii. GENE shows ITG dominant micro-instability and explains the small beneficial effect of the NT for the H-mode as due to a strong reduction of the heat fluxes, when reversing the triangularity, with a relatively high

T

i

stiffness. An improvement of the predicted performances of the NT DTT scenario could come from

ρ

tor

≳
0.9

, as indicated by some recent experiments at the tokamak à configuration variable (TCV) and ASDEX Upgrade.
Extremal statistics for first-passage trajectories of drifted Brownian motion under stochastic resetting
Authors: Guo Wusong , Yan Hao , Chen Hanshuang
Published: February 2024

We study the extreme value statistics of first-passage trajectories generated from a one-dimensional drifted Brownian motion subject to stochastic resetting to the starting point with a constant rate r. Each stochastic trajectory starts from a positive position x
0 and terminates whenever the particle hits the origin for the first time. We obtain an exact expression for the marginal distribution

P
r

(
M

|

x
0

)

of the maximum displacement M. We find that stochastic resetting has a profound impact on

P
r

(
M

|

x
0

)

and the expected value

⟨
M
⟩

of M. Depending on the drift velocity v,

⟨
M
⟩

shows three distinct trends of change with r. For

v
⩾
0

,

⟨
M
⟩

decreases monotonically with r, and tends to

2

x
0

as

r
→
∞

. For

v
c

<
v
<
0

,

⟨
M
⟩

shows a nonmonotonic dependence on r, in which a minimum

⟨
M
⟩

exists for an intermediate level of r. For

v
⩽

v
c

,

⟨
M
⟩

increases monotonically with r. Moreover, by deriving the propagator and using a path decomposition technique, we obtain, in the Laplace domain, the joint distribution of M and the time tm
at which the maximum M is reached. Interestingly, the dependence of the expected value

⟨

t
m

⟩

of tm
on r is either monotonic or nonmonotonic, depending on the value of v. For

v
>

v
m

, there is a nonzero resetting rate at which

⟨

t
m

⟩

attains its minimum. Otherwise,

⟨

t
m

⟩

increases monotonically with r. We provide an analytical determination of two critical values of v,

v
c

≈
−
1.694
15
D

/

x
0

and

v
m

≈
−
1.661
02
D

/

x
0

, where D is the diffusion constant. Finally, numerical simulations are performed to support our theoretical results.
Quantitative evaluation method of operation reliability of substation relay protection device based on improved neural network algorithm
Authors: Wen Tao , Liu Wei , Jiao Shaolin , Zhu Jia
Published: February 2024

With the increase in power demand and the increasing complexity of the power grid, the operation of relay protection devices in substations is often unreasonable. Therefore, a quantitative evaluation method of operation reliability of relay protection devices in substations based on an improved neural network algorithm is proposed. The time-varying probability of misoperation of relay protection in substation is calculated based on the improved neural network algorithm, identifying misoperation behavior of relay protection device, obtaining the optimal hyperplane decision function, selecting kernel function, and construct a quantitative evaluation function of operation reliability of relay protection device. In the evaluation process, two stages of the evaluation process are carried out, namely, reliability block diagram analysis, failure mode evaluation, and verification of relay protection device operation state, so as to complete the reliability quantitative evaluation. The experimental results show that this method can minimize the error of evaluation training and improve evaluation efficiency. At the same time, the error rate is small, which can be controlled within 0.5%.
Energy flow optimization of an electric-gas-heat integrated energy system based on the energy circuit theory
Authors: Cheng Qian , Zhang Xuexia , Gao Yuhan
Published: February 2024

The energy flow optimization of the integrated energy system (IES) can not only decrease the operating cost of the IES but also maximize the utilization rate of renewable energy. To deal with the problem that the optimization results fall into the local optimal solution due to the over-limit of IES state variables, based on the IES energy circuit theory, this paper established an energy flow optimization model of the electric-gas-heat integrated energy system by taking the weighted sum of the operating cost, state variables over-limit penalty cost, and wind and light abandonment penalty cost as the optimization objective. The growth optimizer (GO) algorithm can avoid the local convergence of the optimization results and accelerate the solving speed of the model. Therefore, the effectiveness and feasibility of the model and the optimization method are confirmed by the simulation example.
Assessment method for 220 kv cable outer sheath damage based on bp neural network
Authors: Li Hongke , Xu Han , Wang Siyi , Zhai Yuxin , Liu Bokai
Published: February 2024

220 kV high-voltage submarine cables find extensive application in offshore wind power transmission systems. Ensuring the safe operation of these cables involves accurately detecting and assessing the extent of damage to the cable sheath. This study begins by constructing a finite element simulation model for the cable based on its actual model. Subsequently, a method for evaluating the cable sheath’s damage state is proposed by using a BP neural network. The network takes ambient temperature, current, and six-point temperatures of the damaged section as input characteristics. Results indicate a correct rate of 94.29% for the BP neural network, demonstrating its effective discrimination of cable sheath damage levels. This approach introduces a novel evaluation method for cable sheath damage.
A comprehensive localization and assessment method for SSO in power systems with wind power
Authors: Lv Wan , Xu Peixin , Zhou Feng , Gao Mingyang , Zhao Zhiqin
Published: February 2024

Subsynchronous Oscillation (SSO) is a common dynamic stability issue in power systems that integrate wind power. This paper proposes a comprehensive method for assessing the localization of SSO in wind power integrated systems. The localization method applies the transient energy flow approach to identify SSO sources in systems with wind power. Additionally, a relevant SSO index system is established where the value of each index is calculated. By using the Fuzzy Inference System (FIS) to judge the index, the SSO disturbance source contribution rating of each area is obtained. Simulation cases demonstrate that the localization method of the transient energy flow approach can effectively identify the SSO disturbance source. Moreover, the SSO disturbance source contribution rating method based on FIS can determine the SSO contribution degree of each area, thus identifying the dominant oscillation disturbance sources. The proposed method can provide valuable insights for formulating emergency control measures.
Ultra-short-term forecast of distributed photovoltaic power based on satellite cloud image and LSTM model
Authors: Wang Xunting , Xu Bin , Li Jianglei , Ding Jinjin , Lou Wei
Published: February 2024

Photovoltaic (PV) power generation, with its volatile, intermittent, and random characteristics, and large-scale PV access pose a threat to grid stability. For this reason, predicting the photovoltaic output will help keep the grid safe and stable. On the basis of the influence of cloud groups on solar radiation, a very short-term forecast of distributed PV energy will be made using satellite cloud picture information to improve the forecast accuracy of PV energy production. The paper presents a method to predict distributed PV power at very short notice based on satellite clouds and a network model with Long Short-Term Memory (LSTM). First, extract a subset of meteorological and PV power data from the forecast area as training samples., and the abnormal part of the samples is cleaned by an isolated forest algorithm. Secondly, the occlusion feature is extracted from the satellite cloud image in the same period. Finally, the measured solar irradiance, meteorological information, and obscuration features are input into the LSTM network for prediction, and the photovoltaic power prediction results in the next 4 hours are obtained. The measured PV power of Jinghai Guangfu Power Station in Hefei, Anhui province on the 5th day was the training sample for the prediction of PV power on the 6th day. The prediction results show that the prediction error is 2.73% when a satellite cloud image is added, and 16.15% when a satellite cloud image is not added, and the prediction error is reduced by 13.42%.
Disturbance rejection of interconnected positive systems
Authors: Guo Yu , Xu Shengyuan , Du Baozhu
Published: February 2024

This paper investigates the issue of stability of interconnected systems, where the systems are composed of perturbed positive subsystems and a interconnection matrix. To address the challenge posed by disturbances, a disturbance observer is formulated for disturbance estimation. The estimated disturbance is incorporated into the input of a controller, which is crafted to produce control inputs reliant on both the system state and the estimated disturbance. Using linear copositive functions, a controller design methodology based on linear programming is established. Ultimately, the efficacy of the proposed approach is substantiated through the illustration of numerical example.
Research on motor speed control based on the improved genetic algorithm to optimize fuzzy PID
Authors: Liu Weijun , Zhou Zhiyong , Cao Yinhai
Published: February 2024

This study aims to optimize the speed control effect of fuzzy PID controller in brushless DC motor control, and improve the traditional genetic optimization algorithm to improve fuzzy PID algorithm, mainly for genetic algorithm coding, crossover, and mutation process. In the three processes of the genetic algorithm, real number field coding is used, Taguchi orthogonal table is introduced into the cross-process, and Gaussian variation is applied to the mutation process. In the part of model construction and verification, this study uses Simulink software to build a brushless DC motor model and sets the same conventional parameters for simulation. The simulation results show that the algorithm overshoot and stability time of the fuzzy PID controller optimized by the improved genetic algorithm are obviously improved.
Departure Device Design With Dual Redundancy for the Assistant Landing Gear of Long-endurance UAV
Authors: Yang Tao , Wang Gang , Liang Dong
Published: February 2024

In modern wars and regional conflicts, in order to reduce casualties, more and more unmanned equipment and weapons are utilized. Among them, the UAV is the new favorite in the sky. Application fields of the military UAV are wide and varied. It is found to be used for intelligence reconnaissance, battlefield surveillance, as well as strikes. As for the scout UAV, long endurance is of utmost importance. There is no denying that less weight can result in longer endurance. A departure device for the assistant landing gear of a long-endurance UAV is designed in this paper. The system constitution and working principles are introduced in the beginning. Then, detailed system designs are presented, including the hardware design, software design, and other parts of the departure device. Several static and dynamic experiments are conducted to prove its feasibility. At last, the conclusion part summarizes its applications.
Research on Real-Time Calculation Method of Transformer Temperature Field Based on Reduced Order Model and Sparse Measurement
Authors: Wu Tao , Yang Fan , Farooq Umer , Liu Zhi , Jiang Jinyang
Published: February 2024

The lifespan of transformers is closely related to their operating temperature. Among the existing temperature acquisition methods, the measurement method cannot obtain the complete temperature field temperature, while the numerical calculation method presents the challenge of significant computational expenses. This study theoretically derived how to determine the real-time temperature distribution of transformer windings based on sparse measurement data and reduced order models and solved sensor layout issues, including the number and placement position of sensors. In this study, the maximum calculation error of the temperature distribution is 1.8 K, and the calculation time is 0.38 seconds. The research findings suggest that multiple modes can contribute to the temperature distribution of a transformer. Under a constant load condition, the calculation of transformer temperature can be achieved by utilizing a temperature sensor positioned at the hot spot in conjunction with the first mode.
Investigation on conduction heat dissipation for thermal management in distributed multi-point electronic chips
Authors: Zhan Dongdong , Zhou Jie , Qian Jiyu , Cao Yu
Published: February 2024

A conduction thermal dissipation system is designed for the thermal management of distributed multi-point electronic chips. The heat from the chips is conducted to the flow channel on the two sides with the help of heat pipes. For the purpose of improving the heat dissipation performance, the influence of different flow channel structures was analyzed with the help of numerical simulations. When the fin thickness and spacing are 0.4/0.5 mm, the heat transfer performance is optimal with acceptable flow pressure drop. The results indicated that temperature and uniformity meet the requirements of the electronic chips. The temperature of the chips is lower than 80°C at 1500 W under the condition of the 35°C ethylene glycol solution with 200 L/h. The impact of thermal interface materials on thermal performance was also experimentally studied. The results showed that the graphite interface material has an excellent comprehensive performance with good thermal conductivity and convenient application. This method of distributed multi-point chips and two-sided heat dissipation is more effective in fully utilizing the advantage of heat pipes compared to the traditional usage of evaporation and condensation located on the two sides.
Design of a teleoperated and mixed reality-based electric power live line working robot
Authors: Wang Yi , Qu Fengrui , Wang Xijun , Zeng Songtao , Sun Qizhen , Li Mengyang , Ge Jiafei
Published: February 2024

This paper presents a novel teleoperation force feedback approach combining graphic and haptic feedback for enhanced telepresence. Visual force feedback is modeled through a fitting process, with the force direction established through coordinate transformations. To construct operational environments, a new scene recognition and reconstruction technique is proposed, based on the principles of binocular stereovision. This method is primarily designed for live-line work scenarios, focusing on power line wires. It involves image preprocessing, target image recognition and extraction, binocular stereo measurements, generating depth point clouds, and ultimately reconstructing three-dimensional models of the target objects. Ultimately, a novel electric power live line working robot system with a strong sense of telepresence is achieved, based on teleoperation and mixed reality.
Research on a soft-start method for LCC-LCC compensated bidirectional wireless power transfer system
Authors: Wang Dongsheng , Lin Jinwei , Zhang Le , Ji Tao , Wang Tao
Published: February 2024

The increased popularity of electric vehicles and the pursuit of user convenience makes bidirectional wireless power transfer (BWPT) an attractive technology for charging batteries. To improve the transmission efficiency of BWPT and limit the external radiated magnetic field, it is necessary to ensure the zero-voltage switching (ZVS) operation of the converter on the transmitter-side and limit the transient start-up current of the inverter when the system is working. To solve this problem, this paper proposes a soft-start modulation strategy based on an H-bridge inverter on the transmitter-side. First, the circular characteristics of dual LCC compensation topology are analysed based on an equivalent circuit. Secondly, according to the characteristics of the input impedance angle and current of the transmitter-side, a soft-start control method combining frequency and phase shift control is proposed. Finally, the feasibility of the proposed soft-start modulation strategy is verified on a prototype.
Permanent magnet synchronous motor demagnetization fault diagnosis based on leakage radial magnetic density
Authors: Zhang Meng , Yu Yinquan
Published: February 2024

A method of demagnetization fault diagnosis of permanent magnet synchronous motors is proposed by measuring the radial magnetic density of the leakage field at the external space point of the motor. The method enables non-invasive diagnosis of motor permanent magnet demagnetization faults compared to other methods. In this paper, an analytical model of the radial magnetic density of the leakage field of a surface-mounted permanent magnet synchronous motor under no-load conditions is proposed, and its accuracy is verified by simulation. The influence mode of demagnetization fault on the radial magnetic density of the leakage field is analyzed, which provides a new idea for the diagnosis of motor demagnetization fault.
Transfer operation ride though control strategy of the aircraft power supply system with lithium battery energy storage
Authors: Zhang Xiao , Bu Yuheng , Tian Zhiyuan , Yao Wenli
Published: February 2024

The aircraft power supply system turns towards multi-source, and transfer operation will likely happen during flight missions and fault conditions. The transfer may lead to voltage interruptions and current surges, adversely affecting power quality. This paper proposes incorporating a lithium battery energy storage system (ESS) into the aircraft high-voltage direct current (HVDC) power system. The ESS employs a voltage control model with a lower voltage reference base, facilitating a smooth transfer operation during power interruptions. This approach reduces voltage fluctuations in the power supply system, enhances power quality, and enables seamless power transfer during the transfer operation.
Startup control strategies for pre-fabricated synchronous condensers using static frequency converters
Authors: Zhu Hongchao , Zhang Jie , Zhang Yin
Published: February 2024

In ultra-high voltage transmission systems, a considerable number of dynamic reactive power compensation devices must be equipped. Synchronous condensers are capable of providing substantial amounts of dynamic reactive power. Therefore, distributed prefabricated synchronous condensers can be deployed in ultra-high voltage transmission systems to supply reactive power support to the power grid. The start-up of synchronous condensers can only be achieved through external means. Currently, there are multiple start-up methods available for small-capacity prefabricated synchronous condensers. With the rapid advancements in frequency conversion technology and power electronics, static frequency converters (SFCs) can be utilized to initiate synchronous condensers. This paper investigates the principles of SFC start-up and coordinated control while also configuring protective devices for SFCs based on their structural characteristics and operational principles. A validation platform consisting of one SFC starting two synchronous condensers was established to analyze their start-up time, yielding results demonstrating the ability of SFC-driven distributed small-capacity synchronous condensers to rapidly adjust the power quality of the power grid.
An improved YOLOv5-based model for automatic PCB defect detection
Authors: Li Quanzhou , Zheng Qingwen , Jiang Shixin , Hu Ning , Liu Zhenguo
Published: February 2024

The detection of PCB defects plays an important role in PCB production. To meet the requested quality standard, systematic research was invested in PCB defect detection. The existing PCB defect detection methods are mainly trained by using an artificial defect image dataset, which is much more ideal than the real PCB production process. To deal with the real PCB production defect detection, we collected 3239 image samples and labeled each of them by label-image tool. This paper proposed a new model improved from the basic YOLOv5 framework, adding a scale and self-attention mechanism. The results revealed that this model performed well on defect location and classification with its mAP0.5 reaching 63.4%.
State/fault Estimation and Fault-tolerant Control by SOS approaches under Unmeasurable States
Authors: Liu Yixuan
Published: February 2024

This paper constructs a novel state/fault estimation (SFE) observer and integrated fault-tolerant controller for a series of tunnel diode circuits based on SOS approaches. The unmeasurable states are taken into consideration, expanding the application scope of the method, while a reduced-order observer is proposed to lighten the computational burden. The fault-tolerant control (FTC) unit is co-designed considering the estimation error, and a decoupling technique is employed to reduce computational complexity. For lower conservativeness, stable constraints ensuring the stability of the augmented system under H
∞ performance γ are given in the format of sum-of-squares (SOS). Finally, the validity of the proposed method is verified through a simulation experiment of a tunnel diode circuit.
Study of chromaticity correction methods for a hybrid multi-bend-achromat lattice
Authors: Liu Tao , Wang Lin , Luo Qing
Published: February 2024

The hybrid multi-bend-achromat (MBA) lattice is developed for the demand of higher luminosity at both collider and synchrotron light source. For a hybrid MBA lattice, its negative chromaticities must be corrected with sextupoles, which lead to nonlinearities, thus limiting the dynamic aperture (DA) and momentum aperture (MA). To get efficient injection and long beam lifetime, these nonlinearities must be carefully handled, while it is always difficult to optimize the nonlinearities with limited knobs for the fixed linear lattice. Therefore, conducting chromaticity correction is of importance in linear lattice design that can achieve better nonlinear dynamics. In this paper, three chromaticity correction methods are compared using multi-objective genetic algorithm (MOGA). A hybrid MBA of 2 GeV, as an example, is designed with a natural emittance of 4.4 nm•rad.
Temperature-dependent void nucleation and growth in single-crystal and nanocrystalline iron at extreme strain rates: atomistic insights
Authors: Wang Yuntian , Yang Min , Wei Qiujie , Zhang Ying
Published: February 2024

In this paper, we use molecular dynamics simulation with the embedded atomic method to perform triaxial deformation experiments on single-crystal and nanocrystalline iron at a strain rate of 5×10−9 s−1 and investigate the temperature effect on the void nucleation and growth process. We also evaluate the applicability of the Nucleation And Growth (NAG) model for single-crystal iron. The results indicate that the maximum tensile stress of both single-crystal and nanocrystalline iron decreases as temperature increases, with a reduction of 35.9% for single-crystal iron and 36.2% for nanocrystalline iron from 100 K to 1100 K. It is demonstrated that void nucleation and growth is more favored at high temperature. The void nucleation and growth process in single-crystal iron under high strain rate follows the NAG model. We analyze the sensitivity of the NAG parameters at different temperatures and find that the void nucleation and growth threshold of single-crystal iron is much higher than that of low carbon steel. The results can provide insights for developing fracture models of iron at extremely high strain rate and describing the dynamic damage at continuum length scales.
Design and performance analysis of a discontinuous spiral baffle heat exchanger
Authors: Pan Jin , Jin Feng
Published: February 2024

In this paper, a new type of heat exchanger with discontinuous spiral baffles is designed, and its performance on heat transfer is analyzed by numerical simulation. The research results show that the airflow in shell-side flows by a similar helical way, “Flow dead zone” is not found. The high enthalpy airflow’s temperature decreases about 38% of the inlet air temperature by cooling down with a convective heat transfer coefficient of 344.4 W/(m2·K), while the decrease of the airflow pressure is 30%.
Effect of cavitation on vortex-induced vibration of hydrofoil
Authors: Li Jiangtao , Hu Jian , Zhao Zhenxing , Duan Chuanzhi , Li Fugeng
Published: February 2024

Vortex induced vibration (VIV) is frequently observed in marine structures in offshore platforms, ships and other structures. Under specific circumstances, the vortex shedding frequency is locked into the natural frequency of the structure, resulting in significant and destructive vibration. Moreover, the cavitation in the wake vortex also cause strong trailing edge vibration. In this study, the interaction between VIV and cavitation of two-dimensional hydrofoil was adopted the Shear Stress Transport K-omega model and the Schnerr–Sauer cavitation model. The research findings indicate that the frequency of the wake vortex increases with the decrease of the cavitation number, but the vibration amplitude decreases.
Structure and impedance of TiN coated 304L SS substrates
Authors: Kotlarski G , Ivanov N , Dechev D , Valkov S , Mateev V , Marinova I
Published: February 2024

In the present work, the effect of the deposition time on the structure and electrical impedance of reactive DC magnetron sputtered TiN coatings was studied. The structure of the coatings and the substrates was studied using X-ray diffraction (XRD). The electrical impedance and high frequency stability of the specimens was experimentally measured and the results were indicative of whether the application of the coatings as protective layers between the electrical contact pads of electrical contact systems is feasible.
Rationally designed ultra-fast laser surface texturation of biocompatible temporal scaffolds
Authors: Angelova L , Daskalova A , Rabadjieva D , Sezanova K , Filipov E , Vila X M , Tomasch J , Hromada C
Published: February 2024

The aim of the current work is to create 2D silk fibroin and 3D calcium phosphate temporal cellular scaffolds with specifically enhanced porous topographical design by means of femtosecond laser-induced nano- and micro-scale hybrid surface structuring for application in muscle and bone tissue engineering. The created cellular matrices were ablated in a multistep manner using a Solstice Ace system, delivering laser pulses with pulse duration of 70 fs, at λ=800 nm and a focus spot of 25μm. The samples were positioned on a motorized XY translation stage perpendicular or in a variable angle in respect to the laser beam. Based on the previously performed comparative experimental study, optimal laser structuring conditions and raster patterns were chosen for further enhancement of muscular and Schwann cells environment. The most valuable contribution of the study presented is related to the optimization of the bioactivity properties of the studied cell matrices and their subsequent practical application in tissue engineering.
Ellipsometry of very thin Al2O3-HfO2 stacks for nano-memory applications
Authors: Karmakov Y , Spassov D , Paskaleva A
Published: February 2024

Nowadays, the way towards manufacturing of advanced flash memory devices with conformal layers in stacks or laminates depends on their physical characterisation, i.e. the layer and interface thicknesses, density and composition. The transition dimension between thin and very thin stacks is in the range of few nanometres. The assumption that the oxide layer properties in the very thin stacks are constant in depth or are the same as for the bulk material values is not correct. We have applied ellipsometry (Variable Angle Spectral Ellipsometry, and Multiple Angle Incident Ellipsometry) with appropriate algorithms for data interpretation to investigate very thin Al2O3/HfO2 stacks (5 bioxide blocks) grown by ALD with a total thickness below 20 nm. Depth profiling was used in simulations as a complimentary tool. A quantitative determination of HfO2 volume fraction in the stack depth was obtained. An independent determination of the thicknesses and the composition of blocks in the stacks were achieved. Lorenz-Lorentz mixing model was applied for the estimation of dielectric properties of the different layers in the stack depth.
Comparative study of the sidewall shape and proximity effect in bilayer electron beam resist systems
Authors: Nemec P , Vutova K , Bencurova A , Andok R , Kostic I
Published: February 2024

The experimental investigation and simulation of electron beam lithography (EBL) for bilayer and trilayer resist systems have been carried out. Important parameters of the EBL process, such as dissolution rate, resolution, absorbed energy, and resist profile in the investigated bilayer resist systems, have been studied and discussed. Various combinations of resist layers with positive electron resist have been proposed to examine the effects of lithographic process parameters on the resist profile. The results of this work are intended for use in multilayer resist systems to produce high-frequency electronics, where the fabrication of a T-shaped gate is one of the most crucial processes.
Electrochemical assessment of the barrier ability of galvanic Zn coating primers electrodeposited on low-carbon steel
Authors: Girginov Ch , Kozhukharov S , Boshkova N
Published: February 2024

Low-carbon steel is highly susceptible to corrosion, necessitating protective coatings capable of efficiently shielding its surface from corrosive environments. This brief research focuses on evaluating the protective capacity of electrochemically deposited Zn coatings, both with and without the addition of benzalacetone. Two independent electrochemical methods, Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Scanning (PDS), were employed after exposing the samples to a 0.01 M NaCl model corrosive medium (MCM) for 24 hours. The results demonstrate the discernible barrier performance of the Zn protective films compared to the bare steel substrates.
Growth of 2D MoS2 on sapphire and mica
Authors: Napoleonov B , Petrova D , Rafailov P , Videva V , Strijkova V , Karashanova D , Dimitrov D , Marinova V
Published: February 2024

In this work, we present a study on the epitaxial growth of MoS2 on both sapphire and mica substrates using the Chemical Vapor Deposition (CVD) method. The research focuses on optimizing the growth conditions in order to achieve reproducible results and explore the potential of conventional and Van der Waals epitaxy for synthesizing nanolayers and nanoclusters of transition metal dichalcogenides. By carefully selecting appropriately oriented substrates and performing targeted surface modification, we successfully achieved the desired epitaxial growth. The properties of the obtained structures are thoroughly investigated, with emphasis on their potential applications. This research contributes to the development of scalable and high-quality Transition Metal Dichalcogenide (TMD) growth technique, opening prospects for practical applications in various fields.
Surface functionalization of 3D printed poly-ε-caprolactone by ultrashort laser mirostructuring and ZnO nanolayer deposition
Authors: Filipov E , Delibaltov D , Stefanov R , Blagoev B S , Avdeev G , Terziyska P , Stoykov R , Daskalova A
Published: February 2024

Due to its mechanical properties and good biocompatibility, polycaprolactone (PCL) is a promising material for bone tissue regeneration. However, a major limitation to its use remains the lack of inherent antimicrobial properties and its susceptibility to bacterial colonisation and biofilm formation. A potent strategy for overcoming such issues is surface functionalisation at micro and nano level, which can have a great impact on cell-surface interaction without affecting the integrity of the material. This study presents a novel methodology for surface modification of polymers combining ultrashort laser microstructuring and atomic layer deposition of ZnO. For this purpose, the surface of 3D printed PCL scaffolds was treated with a femtosecond laser (λ=800 nm; τ=75 fs) in order to develop parallel microchannels onto which ZnO nanolayers were further deposited. The presence of ZnO on the laser structured and unstructured scaffolds was detected by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). Both methods confirmed the successful layering as EDX further highlighted a trend that ZnO built up substantially more at the bottom of the microchannels rather than at the top of them. The obtained results would allow proceeding to the next step of the study – investigating the antimicrobial effect of the developed interfaces.
Characterization and antibacterial activity of co-sputtered Cu-doped TiO2 coatings deposited on Ti6Al4V alloy
Authors: Nikolova M P , Ilievska I , Handzhiyski Y , Ivanova V , Apostolova M D
Published: February 2024

Copper has gained increased interest because of its important role in metabolism and antimicrobial activity. In this study, composite target material of Ti and Cu was used to deposit TiO2 coatings doped with copper on Ti6Al4V alloy. The aim was to examine the influence of the applied bias during the deposition of Cu-doped TiO2 coating by sputtering in a glow-discharge in a pure O2 atmosphere for a deposition time of 240 min. Different substrate values, selected from 0 to -150 V, were used in the process. The increase in bias voltage from -50 to - 150 V decreased the thickness of the oxide coatings and improved their adhesion to the substrate while increasing the Cu2O phase at the expense of a CuO phase decrease. Simultaneously, the increase in bias voltage decreased Cu content from about 32 wt% for the -50 V biased down to around 11 wt% for the -150 V biased specimens. The antimicrobial efficacy against E. coli estimated by direct contact experiments on the top of the uncoated (control) and coated Ti6Al4V alloy revealed about 94% inhibition for the -50V biased down to around 37% for the -150 V biased coatings as opposed to the control.