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A numerical survey of parameters to reach ignition condition for axial compression of a large-sized field reversed configuration

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Plasma Science and technology 2024年第5期26卷 47-55页

作者：李宜霖廖晖周海洋孙玄 department of Plasma Physics and fusion Engineering School of Nuclear Science and TechnologyUniversity of Science and Technology of ChinaHefei 230026People’s Republic of China

Field reversed configuration(FRC)is widely considered as an ideal target plasma for magnetoinertial ***,its confinement and stability,both proportional to the radius,will deteriorate inevitably during radial ***,we propose a new fusion approach based on axial compression of a large-sized *** axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the *** parameter space that can reach the ignition condition while preserving the FRC's overall quality is studied using a numerical model based on different FRC confinement *** is found that ignition is possible for a large FRC that can be achieved with the current FRC formation techniques if compression ratio is greater than 50.A more realistic compression is to combine axial with moderate radial compression,which is also presented and calculated in this work.

关键词： field reversed configuration magnetized target fusion axial compression

3D electromagnetic modelling for high-temperature superconducting dynamo flux pumps using T-A formulation

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High Voltage 2024年第2期9卷 367-379页

作者： Luning Hao Fangliang Dong Jintao Hu Qi Wang Haigening Wei Ismail Patel Adil Shah Yuyang Wu Tim Coombs department of Engineering University of CambridgeCambridgeUK Plasma Science and fusion Center Massachusetts Institute of TechnologyCambridgeMassachusettsUSA

A high-temperature superconducting(HTS)dynamo flux pump can inject DC currents into closed-loop HTS magnets without *** enables the realisation of current-lead-free or even through-wall charging systems for high-field applications such as nuclear magnetic resonance/magnetic resonance imaging(MRI)magnets,fusion reactors and *** have proposed many simulation models to understand the working principle of HTS dynamos,few of which are in 3D because of converging ***,the influences of many key 3D parameters in the HTS dynamo are scarcely *** authors propose an efficient 3D modelling method of the HTS dynamo based on the T-A *** rotating magnets are modelled by a ring-shaped permanent magnet with space-time-variant remanent flux density to avoid moving ***,together with the T-A formulation,makes the 3D model efficient and *** accuracy of the model is verified by the experimental instantaneous and time-integrated dynamic *** this model,the authors present systematic case studies to thoroughly explore the influences of the key parameters of a dynamo flux pump on the dynamic voltage and *** proposed modelling method and results could significantly benefit the design and optimisation of HTS dynamos for high-field magnets.

关键词： formulation magnets pump

AMachine Learning Approach to Cyberbullying Detection in Arabic Tweets

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Computers, Materials & Continua 2024年第7期80卷 1033-1054页

作者： Dhiaa Musleh Atta Rahman Mohammed Abbas Alkherallah Menhal Kamel Al-Bohassan Mustafa Mohammed Alawami Hayder Ali Alsebaa Jawad Ali Alnemer Ghazi Fayez Al-Mutairi May Issa Aldossary Dalal A.Aldowaihi Fahd Alhaidari department of Computer Science College of Computer Science and Information TechnologyImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia department of Computer Information Systems College of Computer Science and Information TechnologyImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia department of Networks and Communications College of Computer Science and Information TechnologyImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia

With the rapid growth of internet usage,a new situation has been created that enables practicing *** has increased over the past decade,and it has the same adverse effects as face-to-face bullying,like anger,sadness,anxiety,and *** the anonymity people get on the internet,they tend to bemore aggressive and express their emotions freely without considering the effects,which can be a reason for the increase in cyberbullying and it is the main motive behind the current *** study presents a thorough background of cyberbullying and the techniques used to collect,preprocess,and analyze the ***,a comprehensive review of the literature has been conducted to figure out research gaps and effective techniques and practices in cyberbullying detection in various languages,and it was deduced that there is significant room for improvement in the Arabic *** a result,the current study focuses on the investigation of shortlisted machine learning algorithms in natural language processing(NLP)for the classification of Arabic datasets duly collected from Twitter(also known as X).In this regard,support vector machine(SVM),Na飗e Bayes(NB),Random Forest(RF),Logistic regression(LR),Bootstrap aggregating(Bagging),Gradient Boosting(GBoost),Light Gradient Boosting Machine(LightGBM),Adaptive Boosting(AdaBoost),and eXtreme Gradient Boosting(XGBoost)were shortlisted and investigated due to their effectiveness in the similar ***,the scheme was evaluated by well-known performance measures like accuracy,precision,Recall,and ***,XGBoost exhibited the best performance with 89.95%accuracy,which is promising compared to the state-of-the-art.

关键词： Supervised machine learning ensemble learning cyberbullying Arabic tweets NLP

Massless Dirac perturbations of black holes in f(Q) gravity: quasinormal modes and a weak deflection angle

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Communications in Theoretical Physics 2024年第9期76卷 75-84页

作者： Ahmad Al-Badawi Sohan Kumar Jha department of Physics Al-Hussein Bin Talal University department of Physics Chandernagore College

This article considers a static and spherical black hole（BH） in f（Q） gravity. f（Q） gravity is the extension of symmetric teleparallel general relativity, where both curvature and torsion are vanishing and gravity is described by nonmetricity. In this study, we investigate the possible implications of quasinormal mode（QNM） modified Hawking spectra and deflection angles generated by the model. The Wentzel–Kramers–Brillouin method is used to solve the equations of motion for massless Dirac perturbation fields and explore the impact of the nonmetricity parameter（Q0）. Based on the QNM computation, we can ensure that the BH is stable against massless Dirac perturbations and as Q0increases the oscillatory frequency of the mode decreases. We then discuss the weak deflection angle in the weak field limit approximation. We compute the deflection angle up to the fourth order of approximation and show how the nonmetricity parameter affects it. We find that the Q0parameter reduces the deflection angle.

关键词： black holes in f(Q) gravity deflection angle massless Dirac perturbations quasinormal modes

Structure-preserving algorithms for guiding center dynamics based on the slow manifold of classical Pauli particle

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Plasma Science and technology 2024年第6期26卷 88-102页

作者：张若涵王正汹肖建元王丰 Key Laboratory of Materials Modification by Laser Ion and Electron BeamsSchool of PhysicsDalian University of TechnologyDalian 116024People’s Republic of China department of Plasma Physics and fusion Engineering University of Science and Technology of ChinaHefei 230026People’s Republic of China

The classical Pauli particle(CPP) serves as a slow manifold, substituting the conventional guiding center dynamics. Based on the CPP, we utilize the averaged vector field(AVF) method in the computations of drift orbits. Demonstrating significantly higher efficiency, this advanced method is capable of accomplishing the simulation in less than one-third of the time of directly computing the guiding center motion. In contrast to the CPP-based Boris algorithm, this approach inherits the advantages of the AVF method, yielding stable trajectories even achieved with a tenfold time step and reducing the energy error by two orders of magnitude. By comparing these two CPP algorithms with the traditional RK4 method, the numerical results indicate a remarkable performance in terms of both the computational efficiency and error elimination. Moreover, we verify the properties of slow manifold integrators and successfully observe the bounce on both sides of the limiting slow manifold with deliberately chosen perturbed initial conditions. To evaluate the practical value of the methods, we conduct simulations in non-axisymmetric perturbation magnetic fields as part of the experiments,demonstrating that our CPP-based AVF method can handle simulations under complex magnetic field configurations with high accuracy, which the CPP-based Boris algorithm lacks. Through numerical experiments, we demonstrate that the CPP can replace guiding center dynamics in using energy-preserving algorithms for computations, providing a new, efficient, as well as stable approach for applying structure-preserving algorithms in plasma simulations.

关键词： structure-preserving algorithm averaged vector field classical Pauli particle guiding center dynamics

Comparison of transport coefficients before and after density pump-out induced by resonant magnetic perturbation using a BOUT++ six-field model on the EAST tokamak

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Plasma Science and technology 2024年第6期26卷 111-119页

作者：邓成成刘子奚夏天阳刘彦君厉鹏程龙飞飞高翔王守信李国强刘海庆臧庆李玖瑛杨康宁吴茗甫尹晓宇李弘谢锦林兰涛毛文哲刘阿娣周楚丁卫星庄革刘万东 the EAST Team department of Plasma Physics and fusion Engineering University of Science and Technology of ChinaHefei 230026People’s Republic of China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China

Many experiments have demonstrated that resonant magnetic perturbation(RMP) can affect the turbulent transport at the edge of the tokamak. Through the Experimental Advanced Superconducting Tokamak(EAST) density modulation experiment, the particle transport coefficients were calculated using the experimental data, and the result shows that the particle transport coefficients increase with RMP. In this study, the six-field two-fluid model in BOUT++ is used to simulate the transport before and after density pump-out induced by RMP,respectively referred as the case without RMP and the case with RMP. In the linear simulations,the instabilities generally decreases for cases with RMP. In the nonlinear simulation, ELM only appears in the case without RMP. Additionally, the particle transport coefficient was analyzed,and the result shows that the particle transport coefficient becomes larger for the case with RMP,which is consistent with the experimental conclusion. Moreover, its magnitude is comparable to the results calculated from experimental data.

关键词： BOUT++ resonant magnetic perturbation(RMP) transport coefficients

Burden of routine orthopedic implant removal a single center retrospective study

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World Journal of Orthopedics 2024年第2期15卷 139-146页

作者： Ammar K AlOmran Nader Alosaimi Ahmed A Alshaikhi Omar M Bakhurji Khalid J Alzahrani Basil Ziyad Salloot Tamim Omar Alabduladhem Ahmed I AlMulhim Arwa Alumran department of Orthopedic College of MedicineImam Abdulrahman Bin Faisal UniversityDammam 31441Saudi Arabia Health Information Management and technology department Imam Abdulrahman Bin Faisal UniversityDammam 31441Saudi Arabia

BACKGROUND Open reduction and internal fixation represent prevalent orthopedic procedures,sparking ongoing discourse over whether to retain or remove asymptomatic *** consensus on this matter is paramount for orthopedic *** study aims to quantify the impact of routine implant removal on patients and healthcare facilities.A retrospective analysis of implant removal cases from 2016 to 2022 at King Fahad Hospital of the University(KFHU)was conducted and subjected to statistical *** these cases,44%necessitated hospitalization exceeding one day,while 56%required only a single *** exhibited a 55%need for extended hospital stays,contrasting with 22.8%among the pediatric *** complication rate was 6%,with all patients experiencing at least one ***,34.1%required sick leave and 4.8%exceeded 14 *** anesthesia was predominant(88%).Routine implant removal introduces unwarranted complications,particularly in adults,potentially prolonging *** procedure strains hospital resources,tying up the operating room that could otherwise accommodate critical *** defined institutional guidelines are imperative to regulate this *** To measure the burden of routine implant removal on the patients and *** This is a retrospective analysis study of 167 routine implant removal cases treated at KFHU,a tertiary hospital in Saudi *** were collected in the orthopedic department at KFHU from February 2016 to August 2022,which includes routine asymptomatic implant removal cases across all age *** indications such as infection,pain,implant failure,malunion,nonunion,restricted range of motion,and prominent hardware were *** who had external fixators removed or joints replaced were also *** Between February 2016 and August 2022,360 implants were retrieved;however,only 167 of those who met the inclusion criteria were included in this

关键词： Implant removal Healed fracture Orthopedic implant Complications Healthcare system

Simulation of deuterium pellet ablation and deposition in the EAST tokamak with HPI2 code

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Chinese Physics B 2024年第4期33卷 561-569页

作者：李大正张洁侯吉磊李懋孙继忠 Key Laboratory of Materials Modification by Laser Ionand Electron BeamsSchool of PhysicsDalian University of TechnologyDalian 116024China department of Plasma Physics and fusion Engineering University of Science and Technology of ChinaHefei 230026China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China

Pellet injection is a primary method for fueling the plasma in magnetic confinement *** that goal the knowledges of pellet ablation and deposition profiles are *** the present study,the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST *** ablation and deposition profiles were evaluated for various pellet injection locations,with the aim at optimizing the pellet injection to obtain a deep fueling *** this study,we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and *** ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles:0°,45°,and 60°.The pellet injection on the high field side(HFS)can achieve a more ideal deposition depth than on the low field side(LFS).Among these angles,horizontal injection on the middle plane is relatively better on either the HFS or the *** the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS,it can achieve a similar deposition depth to the one of its corresponding *** the pre-cooling effect is taken into account,the deposition depth is predicted to increase only slightly when the pellet is launched from the *** findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.

关键词： pellet injection pellet ablation HPI2 pellet deposition

Visible-frequency nonvolatile reconfigurable Janus metasurfaces for dual-wavelength-switched and spin-asymmetric holograms

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Photonics Research 2024年第2期12卷 356-368页

作者： HUAN YUAN ZHEQIANG ZHONG bin ZHANG College of Electronics and Information Engineering Sichuan UniversityChengdu 610064China Big Data Analysis and fusion Application technology Engineering Laboratory of Sichuan Province Chengdu 610065China

Janus metasurface holography with asymmetric transmission characteristics provides new degrees of freedom for multiplexing ***,earlier metasurfaces with asymmetrical transmission faced limitations in terms of tunability and *** this study,we propose a metasurface color holographic encryption scheme with dynamic switching and asymmetric transmission at visible frequencies using a low-loss nonvolatile optical phase-change material,Sb_(2)S_(3).Using a modified holographic optimization strategy,we achieved highfidelity asymmetric holographic imaging of a nanostructured *** controlling the incident direction and wavelength of visible light,as well as the level of crystallization of Sb_(2)S_(3),this reconfigurable metasurface enables the precise manipulation of tunable color holographic image *** particular,in the semi-crystalline state of Sb_(2)S_(3),the encoded information can be securely encrypted using a two-channel color-holographic image,whereas only a preset camouflaged image is displayed in the crystalline or amorphous state of Sb_(2)S_(3).The proposed multiencrypted Janus metasurface provides a potential approach for dynamic holographic displays with ultrahigh capacity,holographic encryption,and information storage.

关键词： holographic asymmetric visible