bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the magnetic field intensity on pole erosion of low-power Hall thrusters
Authors: Wang Lei , Li Yi , Wang Zekai , Liu Zijian , Li Hong , Wei Liqiu , Ding Yongjie
Published: May 2023

Magnetic pole erosion is a key life-limiting factor of low-power Hall thrusters. In this study, the effects of the magnetic field intensity near the inner magnetic pole on the pole erosion of a 100 W permanent-magnet Hall thruster at rated operating point were investigated using magnetic field intensity adjustment technology. The experimental results indicate that the erosion rate of the inner magnetic pole decreased considerably with a decrease in the magnetic field intensity near the inner magnetic pole, and the erosion rate can be decreased by over 37.5% when the magnetic field intensity decreased by 20%. Further analysis indicates that the decrease of magnetic field intensity reduces the number of electrons moving along the magnetic field lines to the magnetic pole, and increases the surface potential of the magnetic pole. The reduction of the potential difference between the channel outlet and the magnetic pole leads to a decrease in the current density and energy of the ions sputtered to the magnetic pole, which contributes greatly to the decrease in pole erosion rate. This study provides a reference for the protection of magnetic pole erosion.
Periodic stacking of two dimensional Bismuth bi-layers in Bismuth stearate thin films
Authors: Saini Rimpy , Gautam Devisharan , Roy Sumalay
Published: May 2023

Investigations of single and bilayers of bismuth are one of the most thrusting areas of research in contemporary condensed matter physics and material sciences. This is because such ultrathin layers of bismuth host interesting exotic electronic properties, which are important from both fundamental science and future application perspectives. In the past, many inorganic processes for the synthesis of single and bi-layers of bismuth were reported using physical and chemical vapor deposition techniques. The ultrathin films deposited are found to interact electronically with the substrates due to their proximity to the substrate surface. We introduce a new and easy organic channel for the synthesis of the bismuth multi-bilayers in ambient conditions. Bismuth stearate multi-bilayer thin films are deposited on the hydrophobic silicon and hydrophilic glass substrates using the Langmuir-Blodgett technique. Optical absorption spectroscopy measurements in the infrared region provided information on various bond structures present in those bismuth stearate thin films. Specular x-ray reflectivity (XRR) experiments and their analysis of such thin films unambiguously show the highly periodic stacking of bismuth bilayers along the surface-normal directions within the multilayer film structure. Model-based microstructural analysis of the XRR data further shows that each bilayer of bismuth is well separated (3.5 nm) from other bismuth bilayers by hydrocarbon chains. At these separations, the electronic states of the bismuth bilayers are expected to be non-interacting with each other. The morphology of the surface obtained from field emission scanning electron microscopy supports the XRR analysis. A bandgap of 3.2 eV was obtained for such bismuth stearate thin films from the optical spectroscopy measurements in the UV-visible range. The large separations between the bismuth-bilayers and between the substrate and the bismuth bilayers are expected to minimize the electronic interactions between them.
Measurement of axial stress in high-strength short bolts using ultrasonic attenuation
Authors: Hu Yiliang , Chen Ping , Peng Xianmin , Yin Aijun , Yu Xin
Published: May 2023

Based on the scattering attenuation theory of loaded polycrystalline metals, a bolt axial stress measurement method using ultrasonic echo attenuation is proposed for the problem that the conventional time of flight (TOF) method is difficult to measure the stress of high-strength short bolts. Firstly, the attenuation coefficients of body-centred cubic crystalline materials in the Rayleigh scattering range are described, and the mathematical model between the ratio of the peak of the two bottom echoes and the axial stress of the bolt is further derived. Then, the effects of the transducer wafer diameter, mounting eccentricity and bolt thread on the ultrasonic signal were analysed by finite element simulation, to provide a strategy for transducer selection and mounting. In addition, a magnetic ring clamping device was designed to ensure a tight fit between the transducer and the bolt, and to improve the alignment of both. Finally, a bolt axial stress ultrasonic measurement system was built, and a comparison experiment between TOF method and attenuation method was conducted to predict the axial stress of bolts. The experimental results shown that the average percentage measurement error of the attenuation method proposed in this paper is 4.42%–5.76% lower than that of the conventional TOF method, which is more suitable for measuring the axial stress of bolts.
Identification of low-SNR Coulter signals based on strongly coupled Lorenz-like oscillators
Authors: Zhao Zhijie , Yang Ruyue , Wang Xiaodong
Published: May 2023

A Coulter prototype experiment is established and innovatively combined with coupled Lorenz-like oscillators to identify low-signal-to-noise ratio (SNR) Coulter signals. Coulter signals are collected by a Wheatstone bridge and fitted by Gaussian pulse signals. Using numerical simulation, low-SNR Gaussian pulses are added to the oscillators, and the synchronization mutation phenomena in the chaotic oscillators performed by the time scale transformation are analyzed. The maxima in the phenomena are used to detect the low-SNR pulses and construct an identification formula for different particle sizes. The nonlinear circuit of the oscillators is designed and fabricated. Then, it is applied to process low-SNR Coulter signals in the experiment. By selecting the maxima in the output signals from the circuit, according to the identification formula containing the correction coefficient, the particle size distribution can be obtained. The nonlinear circuit can effectively process low-SNR Coulter signals, which provides a good foundation for reducing the lower limit of detection in Coulter signals.
Absolute distance measurement using frequency sweeping interferometry with large swept range and target drift compensation
Authors: Zhang Shihua , Jin Hao , Zhang Lingqi , Yan Liping
Published: May 2023

Frequency sweeping interferometry (FSI) is an attractive absolute distance measurement (ADM) method because of the advantages of large unambiguity range, simple structure and excellent flexibility. By using a reference interferometer (RI), the calibration of the frequency sweeping range in FSI can be avoided, and the complexity and cost of the system can be further reduced. Then, the measurement accuracy is associated with the accuracy of phase demodulation, the range of frequency sweeping and the compensation of target drift. In this paper, ADM using FSI with large swept range and target drift compensation is presented. A frequency stabilized HeNe laser that travels along the same optical path with the swept source laser was employed to monitor the target drifts of the measurement interferometer and RI. Interference phases of the corresponding interferometers were extracted simultaneously using phase generated carrier demodulation technique, and an accuracy better than 1° was verified by nanometer displacement measurement. Comparative experiments of ADM at a distance of ∼4.5 m with different swept ranges before and after target drift compensation were carried out, and the results demonstrated that larger swept range and target drift compensation could greatly improve the stability and accuracy of measurement.
In situ generation of FeOOH/NiOOH interface in FeS2/NiS2 nanosheets through deep reconstruction for efficient oxygen evolution reaction
Authors: Jiang Xi , Luo Fengting , Liu Ya , Yu Pei , Chen Shijian
Published: May 2023

Transition metal sulfides (TMSs) for electrochemical water splitting undergo significant self-reconstruction to form actual active species favorable for high oxygen evolution reaction (OER) performance. However, the complete self-reconstruction of most reported TMSs in alkaline media is unfrequent and the active species cannot be efficiently used. Herein, self-supported FeS2/NiS2 nanosheet arrays (FeNiS) are deliberately fabricated as pre-catalysts and then accomplished deep phase transformation into low-crystalline and ultrathin FeOOH/NiOOH (FeNiS-R) nanosheets favorable to alkaline OER. Various ex situ characterization studies uncover that the FeNiS-R with abundant interfaces is generated via complete reconstruction during electrolysis and the high-valence Fe and Ni in the FeNiS-R interface are the real active sites for high OER activity. The reconstructed FeNiS-R exhibits a small overpotential of 290 mV at 100 mA cm−2 and favorable durability (≥80 h), much superior to commercial benchmark IrO2. This work provides a promising avenue to achieve the deep reconstruction of TMSs and the targeted design of OER catalysts in energy devices.
Intra- and inter-rater reliability and agreement of stimulus electrodiagnostic tests in post-COVID-19 patients
Authors: da Silva Almeida Isabella , Gomes de Jesus Ferreira Leandro , de Almeida Ventura Álvaro , Mansur Henrique , Babault Nicolas , de Cássia Marqueti Rita , Durigan João Luiz Quagliotti
Published: May 2023

Background. COVID-19 patients may present sequelae, such as neuromuscular electrophysiological disorders (NED), that can be assessed using the stimulus electrodiagnostic test (SET). However, little is known about the reliability and agreement of the SET in post-COVID-19 patients. Objective. We aimed to verify the intra–inter-rater reliability and agreement of SET measurements in the rectus femoris, vastus medialis, vastus lateralis, tibialis anterior, and gastrocnemius lateralis (GL) in post-COVID-19 participants. Methods. We designed an observational prospective study to evaluate 20 (10 males and 10 females) post-COVID-19 patients, age: 44.95 ± 11.07 years, weight: 87.99 ± 19.08 kg, height: 1.69 ± 0.09 m. Two independent raters took two evaluations using the SET on selected muscles. The intra-class correlation coefficient (ICC) and 95% limits of the agreement defined the quality and magnitude of the measures. Results. For intra-rater reliability, all measurements presented correlations classified as high or very high (ICC: 0.71–1.0). For inter-rater reliability, the rheobase, chronaxie, accommodation, and accommodation index presented high or very high correlations, except for the accommodation index of the GL (ICC = 0.65), which was moderate. Conclusion. The reliability of the SET obtained by independent raters was very high, except for the GL accommodation, which presented moderate ICC. Therefore, the SET is a reliable tool for evaluating NED in post-COVID-19 patients.
Specificity of the electron energy distribution function in a low-pressure nitrogen plasma
Authors: Yao Jingfeng , Yan Chai , Yuan Chengxun , Bogdanov Eugene A , Rabadanov Kurban , Chu Zhijia , Kudryavtsev Anatoly
Published: May 2023

In this work, self-consistent simulations of a glow discharge positive column in low-pressure nitrogen plasma are presented. The electron energy distribution function (EEDF) was calculated by solving the complete (i.e. nonlocal) Boltzmann kinetic equation for electrons in both the energy and coordinate (space) variables. The accuracy and range of applicability of the two limiting cases are considered when the kinetic equation is reduced to a dependence on only one variable: kinetic energy in the local approximation or total energy in the so-called totally nonlocal (Holstein–Tsendin) approximation. It is shown that the Holstein–Tsendin approximation, when electron spatial transport dominates the electron energy relaxation (i.e. the ratio between the typical plasma inhomogeneity characteristic length

Λ

and the electron energy relaxation length

λ
ε

), can be used at low nitrogen pressures (when the parameter pR ⩽ 0.05 Torr). With a further increase in pressure, there is a large intermediate region where the EEDF is nonlocal in the sense that the full kinetic equation must be solved. So, even at pR ≈ 0.5 Torr, the EEDF in nitrogen plasma is nonlocal. Therefore, the use of a local approximation to find the EEDF, when all terms with spatial gradients and an ambipolar field can be discarded in the kinetic equation, requires careful verification. Particular attention should be paid to the periphery of the discharge volume, where the self-consistent ambipolar field inevitably exceeds the external electric field that heats the electrons and produces plasma.
Pulsed field magnetization of a rectangular Y–Ba–Cu–O bulk, single grain superconductor assembly
Authors: Wang Yuchen , Ainslie Mark D , Zhou Difan , Zhang Yibing , Cai Chuanbing , Durrell John H , Cardwell David A
Published: May 2023

The practical magnetization of arrays of multiple single grain, bulk high temperature superconductors is essential for practical applications, such as trapped flux rotating machines, magnetic resonance imaging and nuclear magnetic resonance. We report a systematic investigation of the pulsed field magnetization (PFM) of a bulk assembly consisting of two rectangular Y–Ba–Cu–O bulk single grains, in close proximity, at various temperatures. The measurements of the dynamic variation of the magnetic flux density, supported by numerical analysis, reveal that the induced screening currents during the rise of a pulsed field may greatly enhance the flux density in the region of the junction leading to uneven flux penetration and to an increased likelihood of flux jumps in this region. Such coupling between field and current promotes magnetic flux penetration and improves the peak trapped field from 3.01 T for a bulk single grain to 3.11 T for the bulk assembly at 30 K, improving the magnetization efficiency from 80% to 90%. The peak trapped field was further enhanced to 3.39 T and 3.31 T for the single bulk single grain and the bulk assembly, respectively, by employing a two-step multi-pulse PFM process.
Accessing dual toroidal modes in terahertz plasmonic metasurfaces through polarization-sensitive resonance hybridization
Authors: Mallick Soumyajyoti , Rane Shreeya , Acharyya Nityananda , Roy Chowdhury Dibakar
Published: May 2023

Plasmonic metasurfaces have been quite a fascinating framework to invoke transformation of incident electromagnetic waves for a while now. Oftentimes, the building block of these metasurfaces or the unit cells consists of two or more meta-resonators. As a consequence, near-field coupling amongst these constituents may occur depending upon the spatial and spectral separation of the individual elements (meta-resonators). In such coupled structures resonance mode-hybridization can help in explaining the formation and energy re-distribution among the resonance modes. However, the coupling of these plasmonic modes is extremely sensitive to the polarization of the incident probe beam and offers ample amount of scope to harness newer physics. A qualitative understanding of the same can be attained through mode-hybridization phenomena. In this context, here, we have proposed a multi-element metastructure unit cell consisting of split ring and dipole resonators aiming to explore the intricate effects of the polarization dependency of these hybridized modes. Multi-resonator systems with varied inter-resonator spacing (sp = 3.0, 5.0, and 7.0 μm) are fabricated and characterized in the terahertz domain, showing a decrement in the frequency detuning (δ) by 30% (approx.) for a particular polarization orientation of THz probe beam. However, no such detuning is observed for the other orthogonal polarization configuration. Therefore, modulation of the resonance-hybridization is strongly dependent on the terahertz beam polarization. Further, as an outcome of the strong near-field coupling, the emergence of dual toroidal modes is observed. Excitation of toroidal modes demands thoughtful mode engineering to amplify the response of these otherwise feeble modes. Such modes are capable of strongly confining electromagnetic fields due to higher Quality (Q-) factor. Our experimental studies have shown significant signature of the presence of these modes in the Terahertz (THz) domain, backed up by rigorous numerical investigations along with multipole analysis. The calculated multipole decomposition demonstrates stronger scattering amplitude enhancements (∼7 times) at both the toroidal modes compared to off-resonant values. Such dual toroidal resonances are capable of superior field confinements as compared to single toroidal mode, and therefore, can potentially serve as an ideal testbed in developing next-generation multi-mode bio-sensors as well as realization of high Q-factor lasing cavities, electromagnetically induced transparency, non-radiating anapole modes, novel ultrafast switching, and several other applications.
Exploiting potentialities for space-based quantum communication network: downlink quantum key distribution modelling and scheduling analysis
Authors: Wang Xingyu , Li Taoyong , Dong Chen , Wei Jiahua , Yu Huicun , Zhao Shanghong , Shi Lei
Published: May 2023

The goal of the space-based quantum network is to form the backbone of the quantum internet for long-distance secure data transfer, networked distributed quantum information processing, and other applications. Consider that the quantum network evolved from a recent form where a satellite performs a sequence of satellite-to-ground quantum key distribution (SatQKD) missions that allow any two ground nodes to have the symmetric encryption keys, we here develop a framework for the SatQKD downlink modelling and scheduling analysis. Incorporated with the orbital calculation and the meteorological data to downlink SatQKD modelling, the dynamic characteristics of the satellite-to-ground optical transmission could be simulated. Our work shows that the satellite downlink scheduling allows for the possibility to consider different strategies for SatQKD missions such as extending connection for distant ground nodes, prioritized delivery and promoting keys utilization, which may guide design and analysis of future missions for future satellite application.
A novel coercivity enhancement method of Nd-Ce-Fe-B magnets by adjusting anisotropy field distribution and magnetostatic field distribution
Authors: Shen Peng , Wang Chao , Li Jindong , Zhao Yuxin , Sun Xu , Han Rui , Fang Yikun , Zhou Dong , Zhu Minggang , Li Wei
Published: May 2023

In order to give full play to the potential of Nd-Ce-Fe-B magnets and increase the coercivity of magnets with a fixed average composition, the influence of the cooperation effect of anisotropy field and magnetostatic field on their coercivity was studied. Micromagnetic simulations revealed that neither the most heterogeneous composition distribution nor the most homogeneous composition resulted in the highest coercivity. This is due to the variation in a critical field H

crit
which quantifies the cooperation effect of anisotropy field and magnetostatic field. By subtly changing the composition distribution of the Nd-Ce-Fe-B magnets, this work provides a new perspective for further improvement of the coercivity. This adjustment modifies the anisotropy field distribution and the magnetostatic field distribution.
Hall effect on the magnetic reconnections during the evolution of a three-dimensional magnetic flux rope
Authors: Bora K , Agarwal Satyam , Kumar Sanjay , Bhattacharyya R
Published: May 2023

We present a novel Hall magnetohydrodynamics (HMHD) numerical simulation of a three-dimensional (3D) magnetic flux rope (MFR)—generated by magnetic reconnections from an initial 3D bipolar sheared field. Magnetic reconnections during the HMHD evolution are compared with the MHD. In both simulations, the MFRs generate as a consequence of the magnetic reconnection at null points which has not been realized in contemporary simulations. Interestingly, the evolution is faster and more intricate in the HMHD simulation. Repetitive development of the twisted magnetic field lines (MFLs) in the vicinity of 3D nulls (reconnection site) is unique to the HMHD evolution of the MFR. The dynamical evolution of magnetic field lines around the reconnection site being affected by the Hall forcing correspondingly affects the large-scale structures.
Switchable dual-broadband to single-broadband terahertz absorber based on hybrid graphene and vanadium dioxide metamaterials
Authors: Hu Dan , Jia Nan , Zhu Qiaofen
Published: May 2023

Switchable and tunable broadband perfect absorbers have drawn great interest in a wide range of applications, including modulation, energy harvesting, and spectroscopy. Here, we propose a switchable and tunable terahertz (THz) metamaterial absorber with dual-broadband, single-broadband perfect absorption using graphene and vanadium dioxide (VO2). Simulation results show that, when VO2 is in the insulated state, this design behaves as a dual-broadband absorber with over 90% absorption in 0.73 THz–1.53 THz and 3.03 THz–3.64 THz under normal incidence. When VO2 is in the metallic state and the graphene Fermi energy is set as 0.01 eV, this design acts as a single-broadband absorber with over 90% absorption in 1.00 THz–3.55 THz and the fractional bandwidth reaches 112%, which is much larger than the previously reported values. The absorption rate can be dynamically tuned by individually changing the conductivity of VO2 and the Fermi energy of graphene. Moreover, this design exhibits polarization-insensitive and wide-incident-angle behaviors for both TE and TM waves. Such a design may have potential applications in many fields, such as thermal detectors, modulators, and stealth technology.
Efficiency improvement of CTL-free PSCs based on Sn-/Pb-perovskite heterojunction: a numerical approach
Authors: Lin Lingyan , Jiang Linqin , Li Ping , Xiong Hao , Yang Aijun , Li Jiansheng , Sun Wen-Hsien , Qiu Yu
Published: May 2023

Perovskite solar cells (PSCs) with no charge transport layer (CTL) have drawn great attentions due to their simple device structure and low cost. However, the low efficiency hampers their practical applications. In the study, a novel FASnI3/MAPbI3 heterojunction structure is proposed to replace the conventional MAPbI3 absorber layer for efficient CTL-free PSCs. The numerical tool SCAPS-1D is employed to optimize the proposed structure taking into account multiple device and material parameters, such as layer thickness, doping concentration of MAPbI3, electron affinity of FASnI3 and back electrode work function. After optimization, the highest yielded efficiency of the FASnI3/MAPbI3 bilayer structure is 25.34%, which is 54.9% relatively higher than the conventional MAPbI3 single-layer structure (with an optimal efficiency of 16.36%). The simulation results demonstrate the huge potentials of proposed FASnI3/MAPbI3 heterojunction for constructing efficient CTL-free PSCs and provide inspirations for the future development of CTL-free PSCs.
Double roton-minima in bosonic fractional quantum Hall states
Authors: Indra Moumita , Jain Deepak , Mondal Sandip
Published: May 2023

We have studied the collective spin-conserving collective excitation spectra in rotating diluted ultra-cold Bose atoms. Double roton-minima have been observed in the fractional quantum Hall (FQH) states for the two filling fractions (ν) of the first series of Jain's composite fermion sequences. The obtained roton-minima for ν = 1/4 are at the wave-vectors 1.26 and 2.38 and the roton-minima for ν = 1/6 have been shifted to 1.08 and 2.06. Such shift of roton-minima is attributed due to strong correlation between the particles in bosonic FQH-system. Moreover, the number of roton minima observed depends upon number of attached fluxes as well as the ranges of interaction between the particles.
Gravitational wave production from preheating with trilinear interactions
Authors: Cosme Catarina , Figueroa Daniel G. , Loayza Nicolás
Published: May 2023

We investigate the production of gravitational waves (GWs) during preheating with
monomial/polynomial inflationary potentials, considering a trilinear coupling ϕχ2 between
a singlet inflaton ϕ and a daughter scalar field χ. For sufficiently large couplings,
the trilinear interaction leads to an exponential production of χ particles and, as a result,
a large stochastic GW background (SGWB) is generated throughout the process. We study the linear
and non-linear dynamics of preheating with lattice simulations, following the production of GWs
through all relevant stages. We find that large couplings lead to SGWBs with amplitudes today that
can reach up to h
2ΩGW
(0) ≃ 5 · 10-9. These backgrounds are however
peaked at high frequencies f
p ≳ 5 · 106 Hz,
which makes them undetectable
by
current/planned GW observatories. As the amount of GWs produced is in any case remarkable, we
discuss the prospects for probing the SGWB indirectly by using constraints on the effective number
of relativistic species in the universe N
eff.
Light nuclei production in Au+Au collisions at
3 GeV from coalescence model*
Authors: Xu Yue , He Xionghong , Xu Nu
Published: May 2023

The nucleon coalescence model is one of the most popular theoretical models for light nuclei production in high-energy heavy-ion collisions. The production of light nuclei d, t,

He, and

He is studied using the transport model JAM with a simplified afterburner coalescence at

GeV Au+Au collisions. We scan the cut-off of phenomenological coalescence parameters, i.e., the relative spatial distance

and momentum difference

, for the formation of light nuclei by nucleon coalescence to reproduce the light nuclei

spectra measured by the STAR experiment. The results indicate a potential connection between the coalescence parameters and the binding energy as well as the diameter of these light nuclei.
Lepton flavor violating decays of vector mesons in the MRSSM*
Authors: Sun Ke-Sheng , Zhang Wen-Hui , Chen Jian-Bin , Zhang Hai-Bin , Yan Qi-geng
Published: May 2023

In this study, we analyze the rare decays of the neutral vector mesons

and

in the scenario of the minimal R-symmetric supersymmetric standard model using the effective Lagrangian method. The predicted branching ratios are dominated by the mass insertion parameters

, i.e., the off-diagonal inputs, and the contributions of different parts are comparable. Taking into account the experimental constraints on the mass insertion parameters, the predicted branching ratios for the most promising processes

are ten orders of magnitude smaller than the present experimental bounds.
Decoding and geometry of ten finger movements in human posterior parietal cortex and motor cortex
Authors: Guan Charles , Aflalo Tyson , Kadlec Kelly , Gámez de Leon Jorge , Rosario Emily R , Bari Ausaf , Pouratian Nader , Andersen Richard A
Published: May 2023

Objective. Enable neural control of individual prosthetic fingers for participants with upper-limb paralysis. Approach. Two tetraplegic participants were each implanted with a 96-channel array in the left posterior parietal cortex (PPC). One of the participants was additionally implanted with a 96-channel array near the hand knob of the left motor cortex (MC). Across tens of sessions, we recorded neural activity while the participants attempted to move individual fingers of the right hand. Offline, we classified attempted finger movements from neural firing rates using linear discriminant analysis with cross-validation. The participants then used the neural classifier online to control individual fingers of a brain–machine interface (BMI). Finally, we characterized the neural representational geometry during individual finger movements of both hands. Main Results. The two participants achieved 86% and 92% online accuracy during BMI control of the contralateral fingers (chance = 17%). Offline, a linear decoder achieved ten-finger decoding accuracies of 70% and 66% using respective PPC recordings and 75% using MC recordings (chance = 10%). In MC and in one PPC array, a factorized code linked corresponding finger movements of the contralateral and ipsilateral hands. Significance. This is the first study to decode both contralateral and ipsilateral finger movements from PPC. Online BMI control of contralateral fingers exceeded that of previous finger BMIs. PPC and MC signals can be used to control individual prosthetic fingers, which may contribute to a hand restoration strategy for people with tetraplegia.
Simultaneous control of safety factor profile and normalized beta for JT-60SA using reinforcement learning
Authors: Wakatsuki T. , Yoshida M. , Narita E. , Suzuki T. , Hayashi N.
Published: May 2023

Plasma with an internal transport barrier (ITB) will be developed in JT-60SA as an attractive operation appropriate for a steady-state fusion reactor. To achieve the ITB plasma while avoiding magnetohydrodynamic instabilities, it is advantageous to simultaneously control the safety factor (q) profile and the normalized beta (

β

N

). In this study, a control system for simultaneous control of the q profile and

β

N

is studied in simulations prior to the real experiment in JT-60SA. The bootstrap current dominates the total current in the ITB region, which results in a coupling between the pressure profile and the q profile. Thus, it is crucial to control the q profile and

β

N

according to the strength of the ITB. A two-stage neural network (NN)-based control system was developed to address this problem. The first stage estimates the transport properties (i.e. ITB strength) of the plasma from measurements. The second stage consists of several NNs for control of the q profile and

β

N

. According to the ITB strength estimated by the NN in the first stage, the appropriate NN for control is selected from those in the second stage. Each NN in the second stage is trained to control plasmas with different ITB strengths through reinforcement learning employing RAPTOR, an integrated transport code. To validate this system, it is tested in a simulation employing another integrated transport code, TOPICS, to mimic the plasma control in JT-60SA plasmas with various ITB strengths. Stable control of the q profile and

β

N

is achieved in ITB plasmas simulated by both the RAPTOR and TOPICS codes.
Analysis of Ignition Test Failure of Solid Rocket Engine
Authors: Gao Shiyuan , Xu Ze , Zhao Tao
Published: May 2023

This paper reviews the ignition failure of a solid rocket engine in a flight test. A fault tree is established to investigate and analyze the causes. After a series of ground tests to reproduce the faults, it is considered that the humidity of the igniter is the main reason affecting the normal ignition of the engine, and follow-up improvement measures are formulated.
Research on the Dynamic Characteristics of a Low Recoil Swing Chamber Gun Based on the Cased Telescoped Ammunition and Rarefaction Wave Gun Technology
Authors: Han Ru-feng , Tang Peng-bo , Wang Yong-cun , Liu Ye , Cao Yong-jie
Published: May 2023

Based on the theory of a low-recoil rarefaction wave(RAVEN)gun firing cased telescoped ammunition(CTA), the equation system of interior ballistics and kinematics also dynamics were established. The dynamic characteristic curves were obtained by numerical simulation analysis, and the results were verified by firing tests. Compared with traditional closed-breech guns, the low recoil force swing chamber gun keeps the projectile’s muzzle velocity basically unchanged, while the maximum recoil is reduced by up to 74%. Based on these results, the parameters of the inertial breech buffer spring were optimized by numerical simulation optimization algorithms which efficiency is faster than using virtual prototyping technology, while the maximum recoil force of the breech reduced by 14.2% without affecting system performance and structural installation size, which effectively improved the overall performance of the weapon system.
Prescribed Performance Control for Electro-hydraulic Servo System of the Ammunition Manipulator
Authors: Nie Shoucheng , Qian Linfang , Xu Lilin
Published: May 2023

There are stochastic initial disturbances which lead to unexpected tracking errors of the ammunition manipulator during the starting stage. In this paper, a prescribed performance control strategy is proposed for the steady constraint control of the ammunition coordinator. In order to keep the position errors of the ammunition coordinator in the whole tracking control process within the prescribed constraint range, the prescribed performance control theory is adopted to convert the system original error into a new error form that can be restrained through error transformation, and the performance function is designed to constrain the error boundary. The second-order command filter is used to reduce the derivation calculation error of the virtual control variables during the backstepping iteration and the corresponding filtering error compensation algorithm is designed to improve the control accuracy. In addition, adaptive laws are well-designed to compensate the uncertainty of system parameters. The simulation analysis shows that the designed prescribed performance controller obtains good control performance. The convergence and stability of the tracking error of the ammunition manipulator are achieved, and the prescribed performance function prevents the violation of tracking error performance constraints.
Fatigue Life Analysis of Balance Elbow Structure During Firing
Authors: Hongying Xu , Jiaxing Li , Jun Liu , bin Gu
Published: May 2023

As a key component of tracked armored vehicle, balance elbow connects vehicle body and road wheel. Balance elbow transmits large amount of impact energy generated by up and down movement of road wheel to torsion bar in order to reduce impact force on vehicle body. Performance of tracked armored vehicle is improved continuously, higher requirements are put forward for design of balance elbow. Fatigue life of balance elbow during firing while tracked armored vehicle is in parking state is calculated by simplified load spectrum method and rain-flow counting method. Difference between fatigue life results is only 3.81%. Simplified load spectrum method can meet certain accuracy requirements. Rain-flow counting method additionally considers other small stress cycles other than maximum stress cycle, which is more accurate for estimation of fatigue life of balance elbow. Considering uncertainty of load under other working conditions in battlefield, load on tracked armored vehicle during firing is increased by 20%-100%. Fatigue life of balance elbow is significantly reduced by 99.99% after load is increased by 100%.Balance elbow has plastic deformation with low-cycle fatigue characteristic. Influence of change of concave-circle`s diameter at root of mounting surface of balance elbow on its fatigue life is studied. Results show that when concave-circle`s diameter at root of mounting surface of balance elbow is 70mm, fatigue life of balance elbow is highest and 133% higher than design state, which provides an idea for optimization of fatigue life of balance elbow structure.
Research on Recoil Resistance Control Technology of Amphibious Vehicle Weapon
Authors: Zhao JK , Ren GW , Yan SJ , Xu XQ
Published: May 2023

In order to improve the water shooting stability of amphibious vehicle weapon, the recoil motion differential equation of vehicle weapon is established by analyzing the force motion of amphibious vehicle during water shooting. the structure of valve-controlled recoil device and the optimal strategy of grey predictive fuzzy control are determined, and the recoil resistance characteristic curves with or without servo valve and different control voltages are analyzed numerically. And the water motion attitude of the amphibious vehicle under different recoil force. The simulation results show that the valve-controlled recoil device has a good recoil damping platform effect. By adjusting the liquid flow channel of the traditional anti-recoil device by using the servo valve, the recoil resistance of the vehicle weapon can be effectively controlled and the water firing stability of the amphibious vehicle weapon can be improved.
A Review on Life Prediction Methods of Gun Barrel
Authors: Zhang L K , Wang K , Pan G H , Wang D S Y
Published: May 2023

In large caliber gun system, the high speed, high temperature and high pressure gas produced by propellant combustion will cause serious erosion damage to the inner wall of barrel, which will lead to continuous decline of gun performance and termination of the maximum life of barrel. The theories and methods of gun barrel life prediction mainly involve thermodynamics, chemistry, material and machinery science and so on. This paper mainly introduces the main mechanism of gun erosion and the calculation model of gun erosion which involves the numerical solution in internal ballistic combustion process, the heat transfer and erosion calculation of gun barrel. In view of the accurate calculation of parameters such as the temperature of gunpowder gas can more accurately reflect the erosion of inner wall of gun barrel, this paper summarizes the calculation methods of the temperature, thermal physical property parameters and convective heat transfer coefficient of high temperature and high pressure gas in gun barrel. In order to determine the erosion wear quantity and study the effect of heat input on the erosion process of inner wall of gun, erosion experiments are usually required. At present, the common erosion experiments mainly include the measurement of erosion quantity with semi-closed explosive device and the change of surface characteristics of gun steel target with laser pulse heating. By analyzing the criterion of barrel life, the establishment method of barrel life prediction model is studied deeply, and the main barrel life prediction model is introduced, which is convenient to guide engineering application.
Numerical Simulation Research on Rotating Band Dynamic Engraving Process of CTA Artillery
Authors: Shi J F , Qian L F , Chen H B , Zhu Y C
Published: May 2023

In order to study the mechanical mechanism of the dynamic engraving process of the CTA band, the simulation model of the engraving process is established considering the friction and contact characteristics between the interfaces. The adaptive FEM-SPH coupling algorithm is used to obtain the variation law of the temperature and stress distribution of the band, the attitude of the projectile, and the dynamic engraving resistance through numerical calculation. The results show that the band undergoes plastic flow during engraving, and the surface temperature of the band is close to the melting point temperature of the material during the adiabatic engraving. The engraving process presents obvious segmented characteristics, and the initial engraving speed has an important influence on the spatial projectile attitude. The variation of dynamic engraving resistance is quite different from that of the quasi-static model, and the resistance has two ‘rising-decreasing’ processes.
Strength and Modal Analysis of a Gun Barrel under Four Different Strength Theories
Authors: Shuqiang Ge , Mingmin Liu , Feng Xie
Published: May 2023

The barrel with reasonable strength and vibration characteristics needs to be designed for safe and high accuracy firing. The finite element simulation analysis of a gun barrel based on the pressure-length curve load that calculated based on interior ballistic is carried out. Then the strength analysis and modal analysis of the barrel are carried out respectively. The twin shear strength theory is introduced into the design of barrel structure, and barrel elastic ultimate strength analysis method based on the twin shear strength theory is deduced in this paper. The barrel elastic ultimate strength along with the ratio of outer diameter and inner diameter according to three kinds of classical strength theory (i.e., the second, Tresca, and Mises strength theory) and twin shear strength theory were contrasted and analyzed, respectively, and the structural strength of the barrel and corresponding safety coefficient were checked and contrasted based on four different strength theories. The results show that the twin shear strength theory is the most appropriate theory for the design of the barrel. Under the same strength condition, the ratio of outer diameter to inner diameter of the barrel designed by this theory is smallest, and the weight of the barrel is the smallest. The barrel that design based on the twin shear strength theory was safer and not overweight. It also avoids the resonance frequency range and will not cause the occurrence of structure resonance phenomenon.
Analysis of the Development Direction of Small-medium Caliber Artillery
Authors: Liu Jianbin , Zhao Jianzhong , Lin Lun , Zhang Yongtao , Liu Yan
Published: May 2023

Abstract:This paper compares the operational mechanism of artillery to laser weapon, microwave weapon and guided missile, and summarizes the advantage and inherent shortcoming of traditional gun. By carrying out the simulation of different scenarios, the hot probability of artillery to target with different characteristics at different distance is obtained. For giving full play to the advantage of artillery and improving the operational, this paper cording the development direction of artillery technology and proposes the concept of cluster artillery, provides a new idea for the leapfrog discovery of artillery technology.
Damage Effect of Titanium Alloy by Reactive Fragment Oblique Penetration
Authors: Xiang Jing-an , Ji Peng-yuan , Zhou Sheng , Yu Qing-bo
Published: May 2023

The damage effect of reactive fragments on titanium alloy plates is studied through experiment and theoretical analysis. The oblique penetration process and the damage effects of the target influenced by the incident angle and velocity were analyzed. The results show that: Under the condition of 30° incidence angle, the perforation formation modes are extrusion and warping/tearing at 734m/s and 704m/s, respectively, which result to the perforation dimension at 704m/s is 1.56 times of 734m/s; The bulge is formed under the velocity of 1040m/s, at 60° and the reaction ratio of reactive fragments is insufficient. According to the damage morphology of the plate, the damage area in front of the plate can be described as five regions, and the energy density effect on the plate decreases with the increase of the incident Angle.
Latest Research Progress in Modification Technologies of PBO Fibers
Authors: Liu Q , Meng ZR , Chen XD , Xiao ZX , Peng XY
Published: May 2023

This paper focuses on the modification technologies of Poly (p-phenylene benzobisoxazole) (PBO) fibers and their research progress. It is found that the modification of compression resistance, surface inertia, and ultraviolet (UV) aging resistance of PBO fibers can greatly promote the wide application of PBO fibers in advanced composites. More researches are yet to be done on the new modification technologies of PBO fibers in compression resistance, and the future development direction of surface modification and UV aging resistance modification is towards realizing non-destructive modification and large-scale and industrialized online treatment.
Heat Transfer Analysis of the Tantalum-plated Barrel
Authors: Chen S Y , Chen L M , Fu J W , Li Y Z
Published: May 2023

Accurate calculation of temperature distribution in the barrel tube is of great importance for the barrel design. In this paper, a numerical heat conduction model of PCrNi3MoVA tube plated with tantalum coating at the inner surface is established. Based on the finite difference method, the temperature distribution of different coating schemes is calculated. The origin of rifling which is the most serious part of erosion and wear is selected as the object of study. When it comes to different coating thickness, we focused on the variation of temperature at the bore surface and the interface of Tantalum coating and steel substrate. The numerical results show that the thickness of the coating is of great significant to the temperature of the substrate.
Effects of Proportion of BF3-MEA on Curing Properties of AG-80/DDS Resin System
Authors: Wang QF , Huang CX , Chen G , Yu QQ , Wang Z , Wang ZY , Chong L , Wu ZQ , Wei HZ
Published: May 2023

Through differential scanning calorimeter (DSC), the systematic analysis is carried out on the issues including: the curing properties of the resin system composed of 4,4’-diaminodiphenylmethane epoxy resin (AG-80), 4,4’-diaminodiphenylsulfone (DDS) and boron trifluoride monoethylamine complex (BF3-MEA); the effect imposed by the varying content of BF3-MEA on the temperature, extent and rate of reaction; and the effect imposed by the varying DSC heating rates on the curing properties of the AG-80/DDS/BF3-MEA resin system. In the meantime, Ti0, Tp0 and Tf0 are derived, and the curing regimes of the three proportioning schemes are determined accordingly. The gel time of the AG-80/DDS/BF3-MEA resin system is measured through the gel drawing method, and the effect of the BF3-MEA content on the gel time is assessed, so as to determine that 0.7 times of the gel time shall be the pressure time for the forming of composite materials. Furthermore, tests are carried out on the mechanical properties of the resin cast and the carbon fiber composite materials prepared through the three proportioning schemes. The results have shown that when the content of BF3-MEA is 2%, the AG-80/DDS/BF3-MEA resin system outperforms the other proportioning schemes in terms of the curing process and the processability of its composite materials. Besides, the comprehensive mechanical properties of the resin cast and the carbon fiber composite are better.
Research on the application of magnetorheological fluids in artillery buffer system
Authors: Wang Kaizheng , Tian Nan , Xie Yangyang , Yang Gaowei
Published: May 2023

Magnetorheological fluids are an important direction in the research of smart materials. Their high damping force, wide dynamic range, high frequency response and controllable stiffness characteristics make their innovative application in the field of artillery firing technology helpful in solving many technical problems faced during artillery firing. A simulation model of the dynamics of the magnetorheological buffer system is established, the material properties of the magnetorheological fluid performance parameters actively controlled by current are investigated, and a feed-forward control of the operating current in the magnetorheological buffer system is used to analyse the artillery firing recoil and vibration under different operating conditions.The results of the study show that the adoption of a feed-forward controlled magnetorheological buffer system reduces the maximum firing recoil of the artillery and the “platform effect” of the whole recoil process is obvious, which enables active control of the artillery firing process.
Study on Reinforcing and Toughening Modification of MC Nylon
Authors: Wang ZS , Wang YS , Zhang HY , Li GC , Kong GQ , Liu ZY , Chai XM , Luan RQ , Ma HT
Published: May 2023

In this study, we prepared modified potassium titanate whiskers (MPTW) and aluminium oxide (Al2O3) nanoparticles-modified potassium titanate whiskers (AlNPs-MPTW), which were used as reinforcements to produce MPTW MC nylon and AlNPs-MPTW MC nylon, respectively, through in-situ polymerization. Then the thermodynamic stability and mechanical properties of these two kinds of nylon prepared and unmodified MC nylon were studied, proving that AlNPs-MPTW MC nylon possesses better performance. It was found that the prepared AlNPs-MPTW MC nylon with 0.1 wt% AlNP content and 1 wt% MPTW content delivered the optimal properties, specifically tensile strength 97±6 MPa, tensile modulus 3140±45 MPa, flexural strength 116±8 MPa, flexural modulus 3640±53 MPa, and notched impact strength 11.61 kJ/m2. The results showed that multiscale synergistic modified MC nylon possesses remarkable reinforcing and toughening effects, thereby enjoying very broad application prospects.