bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and experimental study on water-sediment flow in a lateral pumping station forebay
Authors: Wang Haidong , Xu Dong , Ding Changfeng , Ran Qihua , Yuan Saiyu , Tang Hongwu
Published: September 2024

Multiple vortex flow patterns are commonly observed in lateral pumping station forebays, particularly in basins with high sediment concentrations. These patterns can lead to pump blockage, sediment deposition, and other issues that disrupt pump station operations. The water-sediment two-phase flow in lateral pumping station forebays is significantly influenced by the start-up combination, yet our understanding remains limited. To address this, the mixture multiphase flow theory is introduced to describe water-sediment dynamics, and the mathematical model is validated with experimental data. By analyzing the characteristics and formation mechanisms of large vortex and multiple small vortex regions in the original scheme, nine different start-up combination schemes were proposed. The research results indicate that, due to the narrow channel and slope effect in the lateral forebay, some of the gravitational potential energy of the water-sediment mixture is converted into kinetic energy upon entering the forebay, thereby increasing the velocity in the main flow area. Additionally, due to the friction and dissipation effects of the two sidewalls, a pressure difference is generated in the main flow area, resulting in the formation of multi-level vortices. Furthermore, the various types of proposed start-up combinations can optimize the flow patterns in the forebay to a certain extent. The preferred scheme improved the uniformity of flow velocity by 18.63% and increased the deviation angle by 17.62°, resulting in a 75.47% reduction in vortex area compared to the original scheme. These research results provide theoretical guidance for optimizing start-up combinations and reorganizing flow field structures to achieve hydrodynamic dredging effects.
Designing a novel image encryption scheme based on an improved 2D logistic map
Authors: Liu Shuang , Ye Xiaolin
Published: September 2024

This paper presents an improved two-dimensional logistic map. Relative to the original logistic map, the improved chaos map has better performance, e.g., larger chaotic range, higher complexity, and boosting sequence. Based on these good performances, a novel encipherment strategy is designed according to the hybrid coding of DNA and S-box algorithm. During the design of the algorithm, the primary operations include chaotic stream generation, permutation, and diffusion. The chaotic streams are constructed from the improved two-dimensional logistic map. The diffusion stage is achieved by the spatiotemporal chaos algorithm. The security test reflects that the design algorithm can effectively defend against external attacks.
A field programmable gate array-based deep reinforcement learning framework for experimental active flow control and its application in airfoil flow separation elimination
Authors: Chen Jie , Zong Haohua , Song Huimin , Wu Yun , Liang Hua , Xiang Jiawei
Published: September 2024

Although deep reinforcement learning (DRL) has gained increasing popularity in numerical studies of active flow control, practical implementations of this technique in experiments remain challenging, particularly for fast air flows. In this study, we proposed a field programmable gate array (FPGA)-based DRL framework for high-speed experimental active flow control. By splitting the training and execution process of artificial neural network and implementing them effectively in central processing unit (CPU) and FPGA, experimental DRL control with an interaction frequency up to 10–100 kHz can be realized, which is two orders higher than that of the traditional CPU-based DRL framework. Such a new framework is tested in the classical problem of airfoil leading flow separation control at Rec = 2.13 × 105, with a plasma actuator and a hotwire serving as the flow disturber and the state sensor, respectively. As a result, experimental DRL control is rather attractive in terms of the time cost, able to find a converged closed-loop control strategy in only one run of 5 min, eliminating the tedious parameter tuning process in open-loop control (time cost: dozens of minutes to hours). Moreover, the magnitude of lift increment in the case of optimal DRL control is 3.2% higher than that of the best open-loop periodical control strategy.
Numerical investigation on the ventilated supercavitating model with propeller
Authors: Xu Chang , Khoo Boo Cheong
Published: September 2024

To achieve stable and continuous supercavitating flow over underwater vehicles, artificial ventilation is implemented, particularly effective at lower speeds. Previous research on supercavitation primarily focused on analyzing ventilated supercavitating flow with various cavitator types and/or ventilation rates. In this investigation, we examine the behavior of ventilated supercavitating flow over an axisymmetric model featuring both a disk cavitator and a Postdam propeller placed at the bow. Utilizing the Large Eddy Simulation turbulence model, Volume of Fluid method, and Kunz cavitation model, our simulation aims to capture the cavitating flow around the propeller and the ventilated supercavitating flow over the model. Validation of our numerical methods is achieved by comparing our results with experimental data of a ventilated model by Chung and Cho [“Ventilated supercavitation around a moving body in a still fluid: Observation and drag measurement,” J. Fluid Mech. 854, 367–419 (2018)] and the cavitating Postdam propeller by SVA Postdam [S. Potsdam, “PPTC smp'11 Workshop,” in Proceedings of the Workshop on Cavitation and Propeller Performance (2011)]. The results show that with a rotating propeller at the bow of the supercavitating model, the cavitating flow extends and stabilizes compared to configurations utilizing a traditional disk cavitator. The presence of the propeller accelerates the formation of supercavitating flow at a consistent incoming flow speed. Additionally, coupling the propeller with the disk cavitator results in significant increases in propeller thrust, torque, and efficiency. While there is an observed rise in model drag, the impact is not substantial.
Hypernetwork modeling and topology of high-order interactions for complex systems
Authors: Feng Li , Gong Huiying , Zhang Shen , Liu Xiang , Wang Yu , Che Jincan , Dong Ang , Griffin Christopher H. , Gragnoli Claudia , Wu Jie , Yau Shing-Tung , Wu Rongling
Published: September 2024

Interactions among the underlying agents of a complex system are not only limited to dyads but can also occur in larger groups. Currently, no generic model has been developed to capture high-order interactions (HOI), which, along with pairwise interactions, portray a detailed landscape of complex systems. Here, we integrate evolutionary game theory and behavioral ecology into a unified statistical mechanics framework, allowing all agents (modeled as nodes) and their bidirectional, signed, and weighted interactions at various orders (modeled as links or hyperlinks) to be coded into hypernetworks. Such hypernetworks can distinguish between how pairwise interactions modulate a third agent (active HOI) and how the altered state of each agent in turn governs interactions between other agents (passive HOI). The simultaneous occurrence of active and passive HOI can drive complex systems to evolve at multiple time and space scales. We apply the model to reconstruct a hypernetwork of hexa-species microbial communities, and by dissecting the topological architecture of the hypernetwork using GLMY homology theory, we find distinct roles of pairwise interactions and HOI in shaping community behavior and dynamics. The statistical relevance of the hypernetwork model is validated using a series of in vitro mono-, co-, and tricultural experiments based on three bacterial species.
Forebrain Eml1 depletion reveals early centrosomal dysfunction causing subcortical heterotopia
Authors: Zaidi Donia , Chinnappa Kaviya , Yigit Berfu Nur , Viola Valeria , Cifuentes-Diaz Carmen , Jabali Ammar , Uzquiano Ana , Lemesre Emilie , Perez Franck , Ladewig Julia , Ferent Julien , Ozlu Nurhan , Francis Fiona
Published: September 2024

Subcortical heterotopia is a cortical malformation associated with epilepsy, intellectual disability, and an excessive number of cortical neurons in the white matter. Echinoderm microtubule-associated protein like 1 (EML1) mutations lead to subcortical heterotopia, associated with abnormal radial glia positioning in the cortical wall, prior to malformation onset. This perturbed distribution of proliferative cells is likely to be a critical event for heterotopia formation; however, the underlying mechanisms remain unexplained. This study aimed to decipher the early cellular alterations leading to abnormal radial glia. In a forebrain conditional Eml1 mutant model and human patient cells, primary cilia and centrosomes are altered. Microtubule dynamics and cell cycle kinetics are also abnormal in mouse mutant radial glia. By rescuing microtubule formation in Eml1 mutant embryonic brains, abnormal radial glia delamination and heterotopia volume were significantly reduced. Thus, our new model of subcortical heterotopia reveals the causal link between Eml1’s function in microtubule regulation and cell position, both critical for correct cortical development.
Autoantibodies neutralizing type I IFNs underlie severe tick-borne encephalitis in ∼10% of patients
Authors: Gervais Adrian , Marchal Astrid , Fortova Andrea , Berankova Michaela , Krbkova Lenka , Pychova Martina , Salat Jiri , Zhao Shuxiang , Kerrouche Nacim , Le Voyer Tom , Stiasny Karin , Raffl Simon , Schieber Pachart Anne , Fafi-Kremer Samira , Gravier Simon , Robbiani Davide F. , Abel Laurent , MacDonald Margaret R. , Rice Charles M. , Weissmann Gaia , Kamal Eldin Tarek , Robatscher Eva , Erne Elke Maria , Pagani Elisabetta , Borghesi Alessandro , Puel Anne , Bastard Paul , Velay Aurélie , Martinot Martin , Hansmann Yves , Aberle Judith H. , Ruzek Daniel , Cobat Aurélie , Zhang Shen-Ying , Casanova Jean-Laurent
Published: September 2024

Tick-borne encephalitis (TBE) virus (TBEV) is transmitted to humans via tick bites. Infection is benign in >90% of the cases but can cause mild (<5%), moderate (<4%), or severe (<1%) encephalitis. We show here that ∼10% of patients hospitalized for severe TBE in cohorts from Austria, Czech Republic, and France carry auto-Abs neutralizing IFN-α2, -β, and/or -ω at the onset of disease, contrasting with only ∼1% of patients with moderate and mild TBE. These auto-Abs were found in two of eight patients who died and none of 13 with silent infection. The odds ratios (OR) for severe TBE in individuals with these auto-Abs relative to those without them in the general population were 4.9 (95% CI: 1.5–15.9, P < 0.0001) for the neutralization of only 100 pg/ml IFN-α2 and/or -ω, and 20.8 (95% CI: 4.5–97.4, P < 0.0001) for the neutralization of 10 ng/ml IFN-α2 and -ω. Auto-Abs neutralizing type I IFNs accounted for ∼10% of severe TBE cases in these three European cohorts.
Phononic Weyl Nodal Lines and Weyl Pairs in van der Waals Heavy Fermion Material CeSiI
Authors: Li 李 Fulei 复磊 , Yu 于 Tianye 天野 , Lai 赖 Junwen 俊文 , Liu 刘 Jiaxi 嘉希 , Liu 刘 Peitao 培涛 , Chen 陈 Xing-Qiu 星秋 , Sun 孙 Yan 岩
Published: September 2024

Topological phonon is a new frontier in the field of topological materials. Different from electronic structures, phonons are bosons and most topological phonons are metallic form. Previous studies about topological phonon states were focused on three-dimensional (3D) materials. Owing to the lack of material candidates, two-dimensional (2D) and van der Waals f-electron-related topological phonons were rarely reported. Based on first-principles calculations, we investigate the topological phononic state in the heavy fermion material CeSiI with a layered structure. Both 3D bulk and 2D monolayers have topological nontrivial states in the rarely seen f electron dominated van der Waals metal. Owing to the PT and C
3z
symmetries, Weyl nodal lines with nonzero Chern numbers exist on the hinge of the Brillouin zone. Protected by C
3z
rotation symmetry, three pairs of Weyl points with ±π Berry phase exist at point K near the frequency of 8 and 10 THz. In addition to the bulk topological charges, corresponding surface/edge states are also systematically analyzed, which gives a consistent understanding. Our results propose another interesting point in the newly discovered rear earth heavy fermion material CeSiI and are helpful for future experimental research of CeSiI topological phonons.
Magnetic field calculation of a uniformly magnetized sphere using solid angles
Authors: Zuo Fulin
Published: September 2024

A new method to calculate the magnetic field of a uniformly magnetized sphere or spherical shell with surface current density

K
=

K

o

sin

θ

using the solid angle concept is presented. The field can be shown easily to be constant inside the shell and dipole-like outside with a direct integral of Biot-Savart’s law without invoking magnetic vector potential or special scalar functions typically used for this classical problem.
Advances in n-type crystalline oxide channel layers for thin-film transistors: materials, fabrication techniques, and device performance
Authors: Kim Gwang-Bok , Choi Cheol Hee , Hur Jae Seok , Ahn Jinho , Jeong Jae Kyeong
Published: September 2024

In this paper, we delve into recent advancements in the fabrication of high-performance n-type oxide semiconductor thin-film transistors (TFTs) through crystallization pathways. The last two decades have seen a rapid proliferation of applications employing amorphous oxide semiconductor (AOS) transistors, from display technologies to semiconductor chips. However, with the growing demand for ultra-high-resolution organic light-emitting diodes, flexible electronics, and next-generation electronic devices, interest in oxide semiconductors exhibiting high mobility and exceptional reliability has grown. However, AOS TFTs must balance the competing demands of mobility and stability. Here, we explore various crystallization methods of enhancing the device performance of oxide semiconductors, alongside the intrinsic challenges associated with crystalline oxide semiconductors. Our discussion highlights the potential solutions presented by controlling crystalline quality in terms of grain size and orientation. We propose that advanced manufacturing techniques coupled with a profound understanding of materials science are needed to effectively address these issues.
Composition, temperature, and size regulation of refractive index in ternary group-Ⅲ nitride alloys: a bond relaxation investigation
Authors: Liu Jin , Zhu Min , Yang Xuexian , Yang Liwen
Published: September 2024

The physical origins of composition-, temperature-, and size-motivated changes in refractive index in crystals have long been a puzzle. Combining the bond-order-length-strength theory, local bond average approach, and core–shell structural model, we investigated the refractive indexes in dependencies of composition, temperature, and size for the ternary wurtzite group-Ⅲ nitride alloys. The theoretical reproduction of the observations disclosed that (i) the doping of small atoms caused the contraction in bond length, the strengthening in bond energy, and the decrease of refractive index, whereas the doping of large atoms led to an elongation of bond length, a weakening of bond energy, and an increase of refractive index; (ii) the refractive index is inversely proportional to the cohesive energy and the cube of the Debye temperature; and (iii) with the gradual decrease in solid size, the coordination number lowers, the bond length contracts, the bond energy gains, the surface-to-volume ratio rises, and the refractive index decreases. The proposed formulation not only shows an in-depth comprehension of the physical essence of the stimuli impact on the refractive index but also is expected to be conducive to the exploitation, optimization, and operation of the new-type photonic, piezoelectric, and pyroelectric nanometer devices for the ternary wurtzite alloys.
Soft sensor modeling based on self-organizing fuzzy neural network with clustering, merging, and splitting scheme
Authors: Sun Jian , Ma Kexin , Liu Yaochen , Wang Jing
Published: September 2024

As a pivotal role in the control, optimization, and monitoring of contemporary industrial processes, soft sensors are frequently employed in the prediction of key quality variables. To achieve accurate prediction of key quality variables in industrial processes, a soft sensor modeling method based on the self-organizing fuzzy neural network with the clustering, merging, and splitting scheme (SOFNN-CMS) is proposed. First, the supervised fuzzy C-means clustering algorithm is proposed to identify the appropriate initial center and width of the fuzzy neural network, obtaining appropriate initial fuzzy rules. Then, a neuron merging and splitting strategy is designed to adjust the structure of the fuzzy neural network, by merging and splitting the hidden neurons according to the distance of clusters, increasing the adaptability of the fuzzy neural network. Besides, to accelerate the convergence of estimation errors, an improved Levenberg Marquardt algorithm is utilized to update neural network parameters in the training phase, realizing the soft sensor modeling of key quality variables. The effectiveness of the proposed SOFNN-CMS neural network is demonstrated on two benchmark problems and an industrial debutanizer column. Finally, the experiments showcase that the proposed SOFNN-CMS neural network can obtain better soft sensor modeling performance with a compact structure.
Tightly coupled stereo vision-inertial odometry based on point and line feature
Authors: Peng Gang , Cao Yihao , Chen Shanliang , Guo Yubo , He Dingxin
Published: September 2024

To improve the accuracy and robustness of visual simultaneous localization and mapping (SLAM) in low-texture environments, this paper proposes a robust and fast stereo vision inertial SLAM pose estimation method that combines point and line features with an inertial measurement unit (IMU). The method tightly couples visual point and line features with IMU constraints, forming a least-squares problem through the error of each constraint term for nonlinear optimization. To address the issues of over-segmentation and time consumption in traditional line segment detection (LSD) algorithms, an improved LSD algorithm is adopted to accelerate line feature extraction. This approach merges nearby line segments based on spatial geometric relationships and filters out invalid segments, improving the time efficiency of the algorithm. Finally, experiments conducted in low-texture environments demonstrate that our algorithm achieves high localization accuracy and robustness.
Bearing remaining life prediction method based on ARAD -ELN and multi-stage wiener process
Authors: Wang Yu , Liu Shujie , Lv Shuai , Liu Gengshuo
Published: September 2024

Stochastic process-based models are extensively utilized in health assessments and Remaining Useful Life (RUL) predictions of bearings. Nevertheless, bearings in actual operation undergo multiple degradation stages, each characterized by a unique trend of degradation. The application of a singular stochastic process for RUL prediction falls short of achieving optimal performance. Consequently, this paper introduces a multi-stage Wiener process-based approach for the prediction of bearings’ RUL. Initially, to address the challenge of imbalanced sample sizes across different degradation stages of bearings, an ensemble learning-based neural network, enhanced by ARIMA Residual Anomaly Detection for identifying bearing degradation stages, is proposed. Subsequently, considering the temporal, unit-to-unit, and nonlinear variabilities of the degradation process at each stage, a Wiener process-based multi-stage degradation model for bearings is developed. A method for parameter estimation and updating, utilizing Kalman filtering and Maximum Likelihood Estimation (K-M), is introduced. Finally, the proposed model is validated using both simulated data and the XJTU-SY bearing dataset. Experimental results from three RUL predictions show that the proposed method outperforms the benchmark model with root mean square error values of 3.61, 2.92 and 7.24, respectively, affirming that the proposed model can precisely classify equipment degradation stages and predict RUL with high accuracy and stability.
Circular motion of a ball in a shallow dish
Authors: Cross Rod
Published: September 2024

A simple experiment is described to illustrate the effects of a centripetal force on a ball rolling in a circular path around a shallow dish. The force acts to move the ball in a circular orbit, it acts to increase the friction force on the ball and it acts to rotate the spin axis of the ball away from the horizontal.
Joint segmentation of tumors in 3D PET-CT images with a network fusing multi-view and multi-modal information
Authors: Zheng HaoYang , Zou Wei , Hu Nan , Wang Jiajun
Published: September 2024

Objective. Joint segmentation of tumors in positron emission tomography-computed tomography (PET-CT) images is crucial for precise treatment planning. However, current segmentation methods often use addition or concatenation to fuse PET and CT images, which potentially overlooks the nuanced interplay between these modalities. Additionally, these methods often neglect multi-view information that is helpful for more accurately locating and segmenting the target structure. This study aims to address these disadvantages and develop a deep learning-based algorithm for joint segmentation of tumors in PET-CT images. Approach. To address these limitations, we propose the Multi-view Information Enhancement and Multi-modal Feature Fusion Network (MIEMFF-Net) for joint tumor segmentation in three-dimensional PET-CT images. Our model incorporates a dynamic multi-modal fusion strategy to effectively exploit the metabolic and anatomical information from PET and CT images and a multi-view information enhancement strategy to effectively recover the lost information during upsamping. A Multi-scale Spatial Perception Block is proposed to effectively extract information from different views and reduce redundancy interference in the multi-view feature extraction process. Main results. The proposed MIEMFF-Net achieved a Dice score of 83.93%, a Precision of 81.49%, a Sensitivity of 87.89% and an IOU of 69.27% on the Soft Tissue Sarcomas dataset and a Dice score of 76.83%, a Precision of 86.21%, a Sensitivity of 80.73% and an IOU of 65.15% on the AutoPET dataset. Significance. Experimental results demonstrate that MIEMFF-Net outperforms existing state-of-the-art models which implies potential applications of the proposed method in clinical practice.
Characteristic study of nitrogen microwave plasma decomposition of ammonia at atmospheric pressure for hydrogen production
Authors: Niu Yu-Long , Li Shou-Zhe , Wang Xing-Chang , Yu Qin-Kun , Yang Dezheng , Wen Xiaoqiong , Zhang Jialiang
Published: September 2024

Ammonia (NH3) is decomposed in afterglow of an atmospheric-pressure nitrogen microwave plasma torch for hydrogen production. Its physiochemical processes are diagnosed by optical emission spectroscopy in terms of the characteristic molecular bands and rotational temperature determined with Boltzmann plot method. The mechanism of NH3 decomposition in plasma afterglow caused by chemical and joule heating is discussed by investigating variations of rotational temperature and concentration of excited species as a function of microwave power and NH3 flow rate, respectively. Additionally, the gas flow field distributed in reaction chamber is numerically calculated using computational fluid dynamics. It is found that enhancing the effective collisions between NH3 molecules and the active species in N2 plasma afterglow aids in achieving a high hydrogen production rate, which is materialized by modifying gas flow field by means of optimizing the gas inlet position and NH3 flow rate and introducing a metal rod in reaction chamber. The experimentally achieved results are as follows: hydrogen production rate of 544 l h−1, energy yield of 274 l kWh−1, and ammonia conversion rate of 86%, respectively.
Investigation in improving the Cs-free negative hydrogen ion production with short-pulse low power in the afterglow of pulse-power-modulated plasma sources
Authors: Yang Wei , Liu Wei , Li Yang , Zhao Yue-Yue , Gao Fei , Ding Ke , Du Cheng-Ran , Wang You-Nian
Published: September 2024

Pulse plasma ion sources have been shown to be capable of achieving high negative hydrogen ion densities (

n

H

−

) or currents. The fast cooling of the electrons and reduction in the electron density (n
e) provide favorable plasma conditions to improve the H− production, with a high density ratio of negative hydrogen ions to electrons during the pulse-off period. The purpose of this research is to further improve the performance of volume-produced H− ion sources based on the pulse power modulation. In this study, a time-modulated negative hydrogen plasma sustained by 10 kHz pulse power at the typical gas pressure of 0.3 Pa was numerically investigated using a global model. The model is compared with measurements obtained in a pulsed radio frequency ion source and shows a reasonable agreement. A steplike low-high power strategy in the active glow period and a short-pulse low power in part of the afterglow period are employed to mitigate overshoot of the electron temperature (T
e) in the initial stage of the pulse period and to optimize H− production in the afterglow, respectively. The model predicts that a small-magnitude, short-duration low power operation in the afterglow increases

n

H

−

and decreases n
e from the onset of the low power until the beginning of the next high power pulse, due to a modest temporary increase in the T
e (less than 2 eV). It facilitates dissociative electron attachments and thus H− formation. The reduction in the n
e indicates that positive ions lost to the walls cannot be compensated by weak ionization. H− production with a low number of co-extracted electrons can be optimized by adjusting the magnitude and duration of the low power in the afterglow.
Effect of substrate temperature on In2S3 thin films using nebulizer spray pyrolysis method for photodetector applications
Authors: Sathish Kumar S , Valanarasu S , Rimal Isaac R S , Vimala Juliet A , Ganesh V
Published: September 2024

In this work, Indium Sulfide (In2S3) thin films were prepared using an economical nebulizer spray pyrolysis technique by various substrate temperatures from 250 °C to 375 °C in steps of 25 °C to evaluate their photo sensing properties. X-ray diffraction (XRD) patterns confirm the presence of In2S3 with face centered cubic structure for all substrate temperatures. The densely packed small spherical grain-sized particles were observed for In2S3 films deposited at 350 °C using Field emission scanning electron microscope (FESEM) analysis. The optical bandgap values were decreased from 3.16 eV to 2.28 eV, with increment in coating temperatures from 250 °C to 350 °C. The high intensity Photoluminescence (PL) peak is observed at 480 nm for the film coated at 350 °C is due to higher rate of electron–hole pair recombination. The photo sensing analysis revealed that the In2S3 thin films deposited at 350 °C, has the maximum responsivity (R) of 9.09 × 10−2 A W−1, detectivity (D*) of 8.25 × 1010 Jones, and external quantum efficiency (EQE) of 21.2%. Increasing the substrate temperature results in a significant enhancement of photo sensing characteristics.
Apparent effective ionization coefficient in N2 and O2 gas mixtures determined with two separate methods
Authors: Talviste Rasmus , Jõgi Indrek , Viidebaum Mikk , Valk Fred , Plank Toomas , Raud Jüri , Paris Peeter
Published: September 2024

N2:O2 gas mixtures are important for applications of atmospheric pressure plasmas such as ozone production, air purification from VOCs and NOx and surface treatments. Fundamental parameters such as the effective ionization coefficient are inputs for theoretical plasma models for applications and must thus be accurately known. This work determined the apparent effective ionization coefficient in N2:O2 mixtures in a broad reduced electric field strength E/N range of 150–1200 Td with two separate methods and compared with BOLSIG+ calculations of reduced effective ionization coefficient. Additionally, the equilibrium distance required to establish a steady-state electron energy distribution was estimated from spatial profiles of optical emission.
High-order solitary waves, fission, hybrid waves and interaction solutions in the nonlinear dissipative (2+1)-dimensional Zabolotskaya-Khokhlov model
Authors: Han Tianyong , Rezazadeh Hadi , Ur Rahman Mati
Published: September 2024

The Zabolotskaya-Khokhlov model (ZKm) is a widely used nonlinear model in the fields of sound, ultrasound, and shock waves. The aims of this paper stems from its examination and rectification of earlier results concerning the N-soliton solutions of nonlinear dissipative (2+1)-dimensional ZKm. By recognizing and incorporating the non-zero values of the dispersion coefficient , this study addresses a significant omission in current research. The findings enhance the comprehension of higher-order soliton behaviors, encompassing bifurcation solitons, higher-order breathers, rogue waves, periodic lumps, and their interactions, which are crucial for both theoretical studies and practical applications in areas like nonlinear optics and fluid dynamics. Subsequent detailed numerical simulations are conducted to elucidate the complex behaviors of the obtained solutions. This thorough exploration provides crucial insights into the intricate patterns exhibited by the nonlinear dissipative (2+1)-dimensional ZKm under different conditions, enhancing our understanding of the underlying physical phenomena.
Microwave absorber surface design for 5G energy harvesting applications
Authors: Tütüncü Bilal , Türktam Ufuk
Published: September 2024

This study presents a high-efficiency microwave absorber for energy harvesting in 5G frequencies. Initially, a unit cell was designed in four stages to efficiently absorb in the targeted frequency region. The results obtained for each stage of the design were analyzed, and additional investigations were conducted for substrate material and thickness based on the optimum performance of the unit cell structure. A unit cell absorber designed on an FR4 a flame-resistant fiberglass/epoxy-based composite, commonly utilized in printed circuit boards due to its favorable electrical insulation properties and low cost. With a thickness of 1.5 mm, the absorber achieved a 98.04% absorption at 3.8 GHz according to simulation results. Subsequently, this unit cell was separately designed and simulated with different periodic arrays to transform into an absorber surface. As a result, high absorption rates of 98.94% and 98.35% were achieved at 3.8 GHz and 4.2 GHz, respectively, in the 2 × 2 array. It was observed that the structure absorbs over 85% within a 1 GHz bandwidth between 3.5 GHz and 4.5 GHz. Finally, a prototype of the absorber surface was manufactured, and measurements were taken in the laboratory environment. Significant agreement was found between the data obtained from these measurements and the simulation results. The results indicate that the suggested absorber surface is well-suited for energy harvesting within the n77 (3.3 GHz to 4.2 GHz) and n78 (3.3 GHz to 3.8 GHz) bands of 5G communication.
Effects of nonthermality on dust-acoustic surface waves with dust rotation
Authors: Hadi Fazli
Published: September 2024

Dust Acoustic Surface Waves (DASWs) real frequency and group velocity are investigated for semi-bounded dusty plasma whose electrons and ions are modeled by Cairn’s Distribution Function (CDF) while massive particles i.e. dust are treated Maxwellian. Kinetic approach based on Vlasov-Poisson’s set of equations is used for the derivation of plasma dispersion relation. It is observed that in the presence of rotational parameter Ω
r
and the variation of nonthermal index α affect both real frequency and group velocity of the wave significantly. This study has wide astrophysical applications.
Near-periodic behavior and parameter-insensitive dynamics of a giant atom interacting with a continuum
Authors: Hansen Jan Petter , Tywoniuk Konrad
Published: September 2024

We consider the solutions of a two-level atom (qubit) coupled to a discretized continuum in the case when the system initially start out in a continuum state. By solving the model we explain the origin of two new pronounced features of a widely used model which has been used for numerous recent studies related to quantum information. In this work we document two new phenomena related to the dynamics which occur when the system is starting out in the continuum. First, dissipatively non-periodic dynamics is replaced by near-periodic oscillatory dynamics when the initial state is switched to be an initially populated continuum state, in combination with a qubit ground state. Second, when the qubit is coupled to two well separated points, the initial state exhibits an exact linear, stepwise decay which is completely insensitive to the coupling parameters.
Study of electrochemical behavior of rGO and metal-organic framework nanocomposite electrodes for supercapacitive applications
Authors: Yadav Meena , Saini Isha , Shekhawat Nidhi , Sharma Swati , Chand Prakash , Singh Vinamrita
Published: September 2024

This research studied the electrochemical performance of reduced Graphene Oxide (rGO) and a nanocomposite comprising rGO and Metal–Organic Framework-5 (MOF-5) for supercapacitor applications. The nanocomposite, synthesized through a solvothermal method, aimed to capitalize on the synergistic effects of combining rGO with MOF-5 under normal laboratory conditions without utilizing autoclave. By adjusting the concentration of the oxidizing agent, the oxidation degree of rGO was effectively regulated, thereby influencing its structural properties. Utilizing the optimized rGO, electrodes were fabricated for both rGO and MOF5-rGO configurations. Electrochemical studies were carried out using a three-electrode (3E) system with a 6M KOH electrolyte. The MOF-5, reduced graphene oxide (rGO), and MOF5-rGO nanocomposite samples were characterized using x-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) to determine their chemical composition and structural information. The Electrochemical Impedance Spectroscopy (EIS) spectra show low internal resistance (Rs) and charge transfer resistance (Rct), indicating higher conductivity of rGO and nanocomposite. The rGO electrode in the 3E system showed a specific capacitance of 65 Fg−1 whereas MOF5-rGO displayed 73 Fg−1 at a current density of 1.2 Ag−1. MOF5-rGO nanocomposite demonstrates better capacitor retention (96%) compared to rGO (90%) at 5A/g. These results indicate that the MOF5-rGO sample is a promising electrode for supercapacitor application.
On the excess loss in FeSiAl soft magnetic composites
Authors: Feng S J , Lv Q R , Kan X C , Yang Y J , Liu X S
Published: September 2024

Aiming at the issue of inconsistent theoretical expression of excess loss in soft magnetic composites, the irrational linear frequency dependence of excess loss W
ex is analyzed. By comparing and analyzing the experimental data of magnetic loss of FeSiAl core under different transverse magnetic fields with the theoretical results, it is determined that the excess loss of FeSiAl composite is proportional to the 1/2th power of the frequency. Meanwhile, it is experimentally discovered that there is a positive correlation between the hysteresis loss and the excess loss of FeSiAl magnetic core, which might provide an effective approach to reduce the excess loss of FeSiAl magnetic core.
Multi-band and polarization-insensitive electromagnetically-induced transparency based on coupled-resonators in a metamaterial operating at GHz frequencies
Authors: Tung Bui Son , Viet Ngo Nhu , Khuyen Bui Xuan , Pham Thanh Son , Do Phong Xuan , Hoa Nguyen Thi , Lam Vu Dinh , Tung Do Khanh
Published: September 2024

The analogy of electromagnetically-induced transparency (EIT) has emerged as an intriguing phenomenon in metamaterials research, enabling precise control over electromagnetic wave propagation. In this work, a metamaterial is investigated to achieve polarization-insensitive and multi-band transparency in microwave region. The metamaterial unit-cell consists of three coupled resonators, engineered to exhibit distinct resonance frequencies within the GHz spectrum and their coupling results in transparency windows. The functionality of the metamaterial is validated experimentally, demonstrating dual-band transparency windows at 4.6 and 6.4 GHz. Additionally, under oblique incidence, a third transparency peak arises, and the achieved triple-band EIT peaks can be maintained above 67% up to an incident angle of 60°. Our work contributes a metamaterial platform offering multi-band EIT behavior and polarization insensitivity at GHz frequencies. The proposed structural design leverages coupled-resonator configurations to achieve enhanced control over electromagnetic wave propagation, promising significant advancements in both fundamental research and practical applications. These include advanced signal processing, high-efficiency filters, and sensors operating in GHz communication and radar systems.
Line intensities of CO near 1560 nm measured with absorption and dispersion spectroscopy
Authors: Huang Q , Tan Y , Yin R-H , Nie Z-L , Wang J , Hu S-M
Published: September 2024

High-precision line intensities are of great value in various applications, such as greenhouse gas metrology, planetary atmospheric analysis, and trace gas detection. Here we report simultaneous measurements of cavity-enhanced absorption and dispersion spectroscopy of the prototype molecule 12C16O using the same optical resonant cavity. Nine lines were measured in the R branch of the

v
=
3
−
0

band. The absorption and dispersion spectra were fitted separately with speed-dependent Voigt profiles, and the line intensities obtained by the two methods agree within the experimental uncertainty of about 1‰. The results demonstrate the feasibility of SI-traceable molecular density measurements based on laser spectroscopy.
Simulations of vertical displacement oscillatory modes and global Alfvén Eigenmodes in JET geometry
Authors: Barberis T. , Kim C.C. , Porcelli F. , Banerjee D. , Hawkes N. , O. Kazakov Ye , Liu Y.Q. , Oliver H.J.C. , Sharapov S.E. , Yolbarsop A. ,   NIMROD Team,   JET Contributors
Published: September 2024

Vertical Displacement Oscillatory Modes (VDOM), with frequency in the Alfvén range, are natural modes of oscillation of magnetically confined laboratory plasmas with elongated cross-section. These axisymmetric modes arise from the interaction between the plasma current, which is in equilibrium with currents flowing in external coils, and perturbed currents induced on a nearby conducting wall. The restoring force exerted by these perturbed currents on the vertical motion of the plasma column leads to its oscillatory behavior. An analytic model for VDOM was proposed by (Barberis et al 2022 J. Plasma Phys.
88 905880511) based on an idealized ‘straight tokamak’ equilibrium with uniform equilibrium current density. This article introduces the first numerical simulations of VDOM in a realistic JET tokamak configuration, using the extended-MHD code NIMROD and drawing comparisons with Global Alfvén Eigenmodes (GAE). The results show qualitative agreement with analytic predictions regarding mode frequency and radial structure, supporting the identification of VDOM as a fundamental oscillation mode in tokamak plasmas. VDOM and GAE are modeled in a representative JET discharge, where axisymmetric perturbations with toroidal mode number n = 0 driven unstable by fast ions were observed. The two modes are examined separately using a forced oscillator within the NIMROD code, which enables a comparison of their characteristics and helps identify the experimentally observed mode possibly as a GAE.
Invariant regimes of Spencer scaling law for magnetic compression of rotating FRC plasma
Authors: Ma Yiming , Zhu Ping , Rao Bo , Li Haolong
Published: September 2024

The scaling laws for the magnetic compression of a toroidally rotating field reversed configuration (FRC) have been investigated in this work. The magnetohydrodynamics (MHD) simulations of the magnetic compression on rotating FRCs employing the NIMROD code (Sovinec et al 2004 J. Comput. Phys.
195 355), are compared with the Spencer’s one-dimensional (1D) theory (Spencer et al 1983 Phys. Fluids
26 1564) for a wide range of initial flow speeds and profiles. The toroidal flow can influence the scalings directly through the alteration of the compressional work as also evidenced in the 1D adiabatic model, and indirectly by reshaping the initial equilibrium. However, in comparison to the static initial FRC equilibrium cases, the pressure and the radius scalings remain invariant for the magnetic compression ratio

B

w
2

/

B

w
1

up to 6 in presence of the initial equilibrium flow, suggesting a broader applicable regime of the Spencer scaling law for FRC magnetic compression. The invariant scaling has been proven a natural consequence of the conservation of angular momentum of both fluid and magnetic field during the dynamic compression process.
Toroidal Alfvén eigenmodes excited by energetic electrons in EAST low-density ohmic plasmas
Authors: Zhu Xiang , Qiu Zhiyong , Bao Jian , Zhang Tao , Liu Haiqing , Luo Chenxi , Tang Tian , Shi Tonghui , Chen Dalong , Qian Jinping , Lin Xiaodong , Gao Xiang , Gong Xianzu , Lin Shiyao , Zeng Long
Published: September 2024

Operation in the quiescent regime with abundant trapped energetic electrons (EEs) has been achieved during the current flattop in EAST low-density Ohmic plasmas. This was facilitated by increasing the electron density to a specified level and subsequently reducing it slowly, resulting in the accumulation of a sufficient number of trapped EEs within the energy range of 150–250 keV. During the phase of decreasing electron density, toroidal Alfvén eigenmodes (TAEs) were observed to be excited by these EEs, with frequencies falling within the range of about 100–300 kHz. The experimental parameters were carefully set to satisfy the resonance conditions for TAE excitation by EEs, aligning well with predictions from ideal MHD theory. Statistical analysis indicated different density dependencies between the frequencies of TAEs and the Alfvén frequencies, due to their different radial excitation positions. The radial positions of the TAEs were found to be influenced by the energy distribution and the evolution of trapped EEs, which in turn were affected by the decay rate of electron density and loop voltage. Measurements of Hard x-rays confirmed an energy distribution characterized by a ‘bump-on-tail’ shape, with the TAEs observed near the energy bump. Theoretical considerations also demonstrate the possibility that the e-TAE can be driven unstable under this experiment condition even if the mode does not rotate in the electron-diamagnetic drift direction.
Reduction of neoclassical bulk-ion transport to avoid helium-ash retention in stellarator reactors
Authors: Beidler C.D. , Drevlak M. , Geiger J. , Helander P. , Smith H.M. , Turkin Y.
Published: September 2024

The reduction of neoclassical energy transport in stellarators has traditionally focussed on optimizing magnetic fields for small values of ‘effective helical ripple’ —

ϵ

eff

, the geometric factor associated with electron

1

/

ν

transport—and relying on the radial electric field,

E

r

, needed to maintain ambipolarity in the plasma, to simultaneously diminish ion energy losses to a tolerable level. As one must generally expect

E

r

<
0

, such a strategy has a drawback for reactor operation, however, as negative values of

E

r

tend to hinder the exhaust of helium ash, and this will become intolerable if it results in excessive fuel dilution. Theoretically, one can show that the neoclassical transport of low-Z impurities depends critically on the ratio

L

11

e

/

L

11

i

, where the

L

11

σ

are the neoclassical particle diffusion coefficients of the bulk-plasma electrons (

σ
=
e

) and ions (

σ
=
i

). Increasing the value of this ratio is shown here to counteract impurity retention, but maintaining good confinement of the bulk species requires this to be achieved by decreasing

L

11

i

rather than increasing

L

11

e

, implying the need for more than just minimization of

ϵ

eff

in reactor design. To assess the prospects of such an endeavor, a predictive 1-D transport code is used here to determine the range of

L

11

e

/

L

11

i

values which arises in simulations of conventionally optimized reactor candidates. This range is found to be considerable, and includes examples with

L

11

e

/

L

11

i

values large enough to provide neoclassical temperature screening of the helium ash and even to flip the sign of the neoclassical convective velocity from inward- to outward-directed. More intriguingly, the strong reduction of

L

11

i

in such cases can also lead to the appearance of

E

r

>
0

(a so-called ‘electron root’) within the core of plasmas having central densities as large as

2
×

10

20

 m−3. Having

E

r

>
0

in the plasma core produces the ideal situation in which all thermodynamic forces aid in the exhaust of helium ash, although this benefit is tempered by the small values of

L

11

z

which accompany an electron root (where

σ
=
z

denotes helium ash). Means are discussed for improving the results presented here, so that avoiding helium-ash retention can be explicitly targeted in future reactor optimizations.
Precise analytical approximations of the eigenvalues of the decatic anharmonic potential
Authors: Veliz M. T. , Martín P.
Published: September 2024

Precise analytical approximations have been determined for the eigenvalues of the ground state of the decatic anharmonic potential x
2 + λx
10 in the one-dimensional Schrödinger equation. The results have been found using the technique multipoint quasi-rational approximation (MPQA). With the new method, power and asymptotic expansions have been determined. The analytic function here obtained is derived connecting both expansions. The maximum relative error of the best analytical approximation here determined is 0.04. However, most of the relative errors for other values of λ, are smaller than 1% (less than 0.01).
Numerical analysis of the Vlasov equation preliminary results
Authors: Angel Nicolás , Calderón Francisco A.
Published: September 2024

We numerically solve a Vlasov equation in two dimensions using the semi-Lagrangian method with a bi-linear interpolation before each advection. We apply this method to a particular case of systems with long-range interactions and two-stream instability. We use the initial conditions as a Maxwellian distribution with perturbations to explore the evolution through the quasi-stationary states to the stability. We analyze this evolution through the electron density, potential, and electric field, where we find the damped oscillations of the two-stream instability. We also explore the behavior of the mainstream affected by the perturbation stream by using the phase space added to the distribution function graphic.