bluuebunny/crossref_metadata_2025_split huggingface dataset:
Symmetry and complexity: a Lie symmetry method to bifurcation, chaos, multistability and soliton solutions of the nonlinear generalized advection-diffusion-reaction equation
Authors: Samina Samina , Jhangeer Adil , Chen Zili 
Published: May 2024

Abstract
This paper deals with the complexities of nonlinear dynamics within the nonlinear generalized advection-diffusion-reaction equation, which describes intricate transport phenomena involving advection, diffusion, and reaction processes occurring simultaneously. Through the utilization of the Lie symmetry approach, we thoroughly examine this proposed model, transforming the partial differential equation into an ordinary differential equation using similarity reduction techniques to facilitate a more comprehensive analysis. Exact solutions for this transformed equation are derived employing the extended simplest equation method and the new extended direct algebraic method. To enhance understanding, contour plots along with 2D and 3D visualizations of solutions are employed. Additionally, we explore bifurcation and chaotic behaviors through a qualitative analysis of the model. Phase portraits are meticulously scrutinized across various parameter values, offering insights into system behavior. The introduction of an external periodic strength allows us to utilize various tools including time series, 3D, and 2D phase patterns to discern chaotic and quasi-periodic behaviors. Furthermore, a multistability analysis is conducted to examine the impacts of diverse initial conditions. These findings underscore the efficacy and practicality of the proposed methodologies in evaluating soliton solutions and elucidating phase dynamics across a spectrum of nonlinear models, offering novel perspectives on intricate physical phenomena
Super-X and conventional divertor configurations in MAST-U ohmic L-mode; a comparison facilitated by interpretative modelling
Authors: Moulton D. , Harrison J.R. , Xiang L. , Ryan P.J. , Kirk A. , Verhaegh K. , Wijkamp T.A. , Federici F. , Clark J.G. , Lipschultz B. 
Published: May 2024

Abstract
Measurements are presented, alongside corresponding interpretative SOLPS-ITER simulations, of the first MAST-U experiments comparing ohmically heated L-mode fuelling scans in Conventional divertor (CD) and Super-X divertor (SXD) configurations. In experiment, at comparable outer mid-plane separatrix electron density,

n

e
,
sep,OMP

, the maximum lower outer target heat load was found to be a factor 16

±

7

lower in SXD compared to CD. In simulation, a factor 26.8 reduction was found (slightly higher than the experimental range), suggesting an additional reduction in SXD compared to the factor 9.3 expected from geometric considerations alone. According to the simulations, this additional reduction in the SXD is due to a net radial transport of the energy remaining downstream of the

T
e

=
5

eV location. This energy is carried out of the critical (highest heat load) flux tube by deuterium atoms, demonstrating the importance of a longer legged divertor which provides space for this to occur. Importantly, in both simulation and experiment, the SXD has minimal impact on the upstream ne
and Te
profiles. Spectral inferences of detachment front movement in SXD compare well between simulation and experiment. In regions of high magnetic field gradient, the parallel movement of the front towards the X-point becomes less sensitive to increasing

n

e
,
sep,OMP

, in qualitative agreement with simplified models and previous predictive simulations. Additional aspects, regarding the target ion flux rollover, upstream separatrix temperature and drift effects, are also presented and discussed.
Tokamak divertor plasma emulation with machine learning
Authors: Holt G.K. , Keats A. , Pamela S. , Kryjak M. , Agnello A. , Amorisco N.C. , Dudson B.D. , Smyrnakis M. 
Published: May 2024

Abstract
Future tokamak devices that aim to create conditions relevant to power plant operations must consider strategies for mitigating damage to plasma facing components in the divertor. One of the goals of MAST-U tokamak operations is to inform these considerations by researching advanced divertor configurations that aid stable plasma detachment. Machine design, scenario planning and detachment control would all greatly benefit from tools that enable rapid calculation of scenario-relevant quantities given some input parameters. This paper presents a method for generating large, simulated scrape-off layer data sets, which was applied to generate a data set of steady-state Hermes-3 simulations of the MAST-U tokamak. A machine learning model was constructed using a Bayesian approach to hyperparameter optimisation to predict diagnosable output quantities given control-relevant input features. The resulting best-performing model, which is based on a feedforward neural network, achieves high accuracy when predicting electron temperature at the divertor target and carbon impurity radiation front position and runs in around 1 ms in inference mode. Techniques for interpreting the predictions made by the model were applied, and a high-resolution parameter scan of upstream conditions was performed to demonstrate the utility of rapidly generating accurate predictions using the emulator. This work represents a step forward in the design of machine learning-driven emulators of tokamak exhaust simulation codes in operational modes relevant to divertor detachment control and plasma scenario design.
Experimental investigation of PDI bifurcation of lower hybrid waves during electron density ramp-up in EAST
Authors: Yan G.H. , Ding B.J. , Wu C.B. , Li M.H. , Baek S.G. , Napoli F. , Zhou T.T. , Geng K.N. , Yan N. , Wang M. , Zhang X.J. , Xu H.D. , Yang J.H. , Ma W.Q. 
Published: May 2024

Abstract
The effect of parametric decay instability (PDI) on the current drive efficiency of 4.6 GHz lower hybrid (LH) waves in EAST is investigated experimentally, showing the PDI channel bifurcation of LH waves for the first time in EAST. First, experiments with three platforms of LH power were performed, achieving the LH power required for the PDI occurrence. Second, PDI bifurcation experiments were further carried out by ramping up the plasma electron density. The loop voltage increases with an increase in density, implying a decrease in the current driven by the LH wave. PDI bifurcation during electron density ramp-up was studied by analyzing the parallel refractive index (

n
∥

) and the frequency spectrum broadening, which is measured with a radio frequency magnetic probe array recently installed close to the LH antenna. It is observed for the first time that they both first increase with density, then there is not much variation and a clear sideband in the frequency spectrum is also observed when the density is up to

4
×

10

19

m

−
3

, suggesting a change in the PDI channel. Calculation of the mode growth rate driven by PDI shows that when the edge electron density is up to

1.9
×

10

18

m

−
3

, the growth rate of the ion cyclotron quasi-mode (ICQM) will exceed that of the ion sound quasi-mode (ISQM), quantitively explaining that with an increase in density, the PDI channel partly transits from the ISQM to the ICQM channel. Studies provide a possible way to reduce the power deposition in the edge region and improve drive capability by means of mitigating PDI behavior.
Aerodynamic characteristic analysis of blast wave lateral sweeping aircraft based on CFD transient numerical simulation method
Authors: Yuhong Cai , Jianchao Niu , Duojia Huang , Mailiang Li , Zijie Chen 
Published: May 2024

Abstract
Blast wave overpressure and dynamic pressure significantly change the surface pressure distribution of the aircraft and resulting in transient aerodynamic forces when the blast wave sweeps the aircraft laterally. These transient aerodynamic forces will pose a serious threat to flight safety. In this paper, the aerodynamic parameters of aircraft components under lateral sweep of blast waves are studied by the Computational Fluid Dynamics (CFD) numerical simulation method, and the waveform characteristics of the dominant aerodynamic parameters of the aircraft key components are analyzed according to the CFD simulation results. The research method can provide reference and guidance for the study of aircraft flight safety under blast wave sweeping.
Researches on the aerodynamic and stealth characteristics for flying wing fighter
Authors: Shi Longlong , Xia Lu , Zhang Meng , Deng Jun , Zhang Wei 
Published: May 2024

Abstract
Flying wing configuration fighter is very promising for the advanced fighter in the future. This paper studies the aerodynamic and stealth characteristics of flying wing fighter. Firstly, the effect of sharp leading edge on the subsonic, transonic lift and drag characteristics and stealth characteristics of the fighter are studied. The results show that the sharpen of leading edge of the inboard wing could greatly improve the lateral stealth characteristics while maintaining the subsonic and transonic lift characteristics. In order to furtherly improve its aerodynamic and forward stealth characteristics, the aerodynamic/stealth collaborative design optimization method based on discrete adjoint is carried out. And the results presented that there are obvious contradictions in the subsonic, transonic and supersonic lift characteristics of the flying wing fighter, and the improvement of the forward stealth characteristics will also damage the subsonic lift characteristics. Therefore, it is necessary to make a compromise between the subsonic, transonic and supersonic lift characteristics, drag characteristics and stealth characteristics in the shape design of flying wing fighter.
Stochastic robustness analysis of wing-aileron flutter suppression systems
Authors: Vindigni Carmelo Rosario , Mantegna Giuseppe , Esposito Antonio , Orlando Calogero , Alaimo Andrea 
Published: May 2024

Abstract
In this work a stochastic robustness analysis approach is used to compare the performances of two non-linear flutter suppression systems designed for stabilization of a wing-aileron lifting structure. A reduced order modelling approach based on an alternative aeroelastic beam finite element is presented and used for the flutter suppression systems design, which are driven by a simple adaptive controller and a sliding mode controller, respectively. A heuristic algorithm is used to determine the simple adaptive controller invariant parameters at the design point while a simple parametric study is performed to tune the sliding mode controller. The performances of each closed loop system are evaluated taking into account mass, stiffnesses, and aerodynamics uncertainties of the aeroelastic plant also considering the presence of discrete gust disturbances.
Drag reduction study based on boundary layer combustion on single expansion ramp nozzle
Authors: Chang H , Sun B , Gan Y Z 
Published: May 2024

Abstract
In hypersonic flight, frictional drag is an important factor affecting the overall engine performance. The wall frictional drag analysis and drag reduction technology of a unilateral expanding tail nozzle under typical working conditions are carried out by means of two-dimensional Reynolds-averaged N-S equations and SST k − ω turbulence model. The effects of hydrogen injection and combustion with different mass flow rates under different jet positions on the wall friction resistance are analyzed and compared, and the results show that, under the appropriate opening position, a better drag reduction effect can be obtained by injecting hydrogen with a mainstream flow rate of about 2.5%, which can achieve a reduction of 43.7%.
Influence of thermochemical non-equilibrium effects on non-uniform entrance scramjet nozzle
Authors: Wang Jinping , Zhuo Changfei , Ren Xiaobin 
Published: May 2024

Abstract
The high Mach number scramjet nozzle flow has prominent non-uniform characteristics and high-temperature non-equilibrium effects. Thus, the thermochemical non-equilibrium gas model was developed for simulating flows in the non-uniform and uniform entrance of a Mach 10 hydrocarbon fuel scramjet nozzle. The results show that the non-uniform entrance has a higher non-uniform degree in the flow-field compared to the uniform entrance. Additionally, the expansion degree inside the nozzle is greater and the thermal non-equilibrium effects downstream of the nozzle exit are stronger. The non-uniform entrance condition has a more intense chemical reaction near the nozzle exit but has less impact on the flow parameters. For the nozzle performance, under the influence of the non-uniform entrance, the greater gas expansion degree inside the nozzle results in a lower pressure acting on the upper wall, and then the nozzle thrust decreases by 1.68%. Hence, the structural design and performance optimization of the high Mach number scramjet nozzle must consider entrance non-uniform characteristics and thermochemical non-equilibrium effects.
Aero-acoustics study of coupled cavities in close proximity along a rectangular flow duct at low Mach number
Authors: Tang Y J , Gan L , Liang C , Gao J L , Zhang S Z 
Published: May 2024

Abstract
In present study, a series of flow induced noise experiments were investigated by a coupled cavity with low Mach number flow. A new signal processing method was derived to analyze the turbulence sound field and its propagation inside the coupled cavity region. In order to investigate the sound field in the presence of flow throughout the coupled cavity regions, a transfer function technique for transducer signals was developed. Experimental result and analysis show that the significant sound attenuation effect is caused by the pressure fluctuation that gives rise to canceling waves along the main duct section. In the presence of the acoustic excitation and the duct flow, the Rossiter type of feedback is the dominant mechanism responsible for the sound amplification effect. This type of feedback mechanism also results in relatively tonal sound generations at various frequencies within the working bandwidth of the coupled cavities.
A hybrid dynamics modeling method for micro-turbine engine thrust vectoring
Authors: Chao Zhang , Aobo Shi , Guangqi Cheng , Jian Sun 
Published: May 2024

Abstract
Thrust vector control technology is widely used in modern advanced aircrafts, space shuttles and unmanned aerial vehicles, etc. An accurate thrust vector mathematical model is of great significance to enhance the thrust vector control effect. In this paper, the P200 micro-turbine engine with an axisymmetric thrust vector nozzle placed at the rear is taken as an example, A hybrid thrust vectoring dynamics modeling method consisting of engine speed model, engine thrust model, actuator dynamics model, airflow angle model and thrust loss coefficients is proposed. The engine speed model is of Linear Parameter Varying (LPV) model with each segment is characterized by a First Oder Plus Dead Time (FOPDT) model. The engine thrust model is characterized as a cubic polynomial function of engine speed. The actuator’s dynamic model is a FOPDT model. The nozzle airflow deflection angle is proportional to the airflow deflection angle. the thrust loss coefficient is approximated by a cosine relationship with the airflow deflection angle. The experimental results show that the established model can well characterize the dynamics of the thrust vector system.
CF-LSTM-based post-maneuver position prediction for GEO spacecraft
Authors: Long X , Yang L P , Huang H , Hu J X , Qiao C Y 
Published: May 2024

Abstract
Prediction of the position of Geosynchronous (GEO) spacecraft after a maneuver is crucial for space domain awareness (SDA), as it can enhance the flexibility of the space surveillance network (SSN). The longitude is a unique parameter that can be freely assigned to GEO spacecraft. In this paper, we propose a prediction model for the longitude of a GEO spacecraft based on Causal Feature Long Short-Term Memory networks (CF-LSTM). Initially, we analyze the historical data of GEO spacecraft in a time-series geographic position and identify the causal parameters of longitude using the Gaussian perturbation equation. Subsequently, we present the CF-LSTM to predict the longitude. Our experimental analysis shows that the proposed method reduces the mean absolute error (MAE) and mean square error (MSE) by 60.92% and 18.75%, respectively, compared to conventional LSTM.
Physical and mechanical impact of Y2O3 on (Cu-7Ag) electrical contact alloy
Authors: Raheem Maryam , Al-Ethari Haydar , Abbas Sundus 
Published: May 2024

Abstract
In this study, (Cu-7Ag) alloy was synthesized through powder metallurgy rout and explored the effect of adding yttrium oxide (Y2O3) with three different volume fractions 2, 4, and 6 vol.%. The effects were recorded on the electrical conductivity, the hardness, and the wear rate of the prepared samples. The base samples were sintered at 850 °C for 4 hours, while the composite samples were sintered with two holding times: at 550 °C for 2 hours and at 850°C for 4 hours. All of the sintered samples were homogenized at 777 °C for an hour followed by aging at 400 °C for 8 hours. The base alloy (Cu-7Ag alloy) showed higher conductivity but poor hardness and poor wear resistance. Best balance between the improvement of mechanical properties and suitable electrical conductivity had been obtained with Cu-7Ag+4vol.% Y2O3 composite sample.
Integrated design optimization of ducted lift fan for lift enhancement and noise reduction based on nested NFFD control body
Authors: Zhang Linxuan , Sun Jian , Cai Xiaofei , Zhang Chao , Ding Yuheng 
Published: May 2024

Abstract
In order to enhance the aerodynamic performance and reduce the aerodynamic noise of the coaxial dual-rotor ducted fan, this paper proposes a stepwise optimization strategy based on nested NFFD (Nurbs-Based Free-Form Deformations) control body parameterization. This strategy takes into account the optimization of aerodynamic performance, which involves significant deformations, and noise reduction, which requires fine deformations. By doing so, it effectively addresses the issue of drastically increased computational complexity and time consumption associated with conventional multi-objective optimization methods. By designing the aerodynamic shape of the blades, along with aerodynamic performance parameter calculation and aerodynamic noise calculation modules, it is possible to achieve lift enhancement and noise reduction for the ducted fan. The numerical simulation results demonstrate that the flow field over the optimized blade surface is improved significantly. The lift has increased from 3.45N to 3.54N, resulting in a 2.6% enhancement. Additionally, the noise level has decreased from 72.33dB to 69.52dB, achieving a noise reduction of 2.81dB.
Design of dynamic test specimens and fixtures for large structural components of civil aircraft
Authors: Lyu Yuanzhou , Li Ruowei 
Published: May 2024

Abstract
In the course of designing and certifying civil aircraft, a significant number of dynamic tests are necessary. If the test specimen is too large in volume or weight, it will place higher demands on the loading capacity of the test equipment. The main focus in the design process of dynamic test specimens is to ensure consistency in the dynamic characteristics compared to the original structure, specifically with regard to natural frequency and mode shapes. Factors such as stiffness, damping, and boundary conditions are taken into consideration. In order to facilitate test implementation and reduce manufacturing costs, a combined approach involving finite element analysis and experimental verification is employed to provide guidance for the design of dynamic test specimens and fixtures for civil aircraft.
Developing and correction methods for a one-dimensional axial flow compressor model
Authors: Deng Haomin , Zhou Wenxiang , Cong Jingmei , Zhang Chenyang , Wu Jichang , Huang Jinquan 
Published: May 2024

Abstract
This paper establishes a one-dimensional model of an axial flow compressor using the Average Mid-Diameter Method and employs polynomials to adjust the off-design stagger angle and off-design loss models. Furthermore, a model stepwise correction strategy based on the Particle Swarm Optimization (PSO) algorithm is proposed. The accuracy of the corrected one-dimensional axial flow compressor model was verified and integrated into the overall engine model for validation. Simulation results indicate that the maximum error in calculating the characteristics of the established one-dimensional axial flow compressor model does not exceed 6%, and the maximum error in simulating the overall engine model remains below 4%. These findings validate the effectiveness of modeling and correction methods for a one-dimensional axial flow compressor model targeting aero-engine component-level model.
Application of CNN-IndRNN model combined with residual structure in aircraft engine EGT prediction
Authors: Xiao Dasheng , Xiao Hong 
Published: May 2024

Abstract
The convolutional neural network (CNN), independently recurrent neural network (IndRNN), and residual structure are used to establish a deep learning model for predicting the exhaust gas temperature (EGT) of aircraft engines. Compared to traditional RNN, the IndRNN has an independent recurrent weight matrix in each unit unfolded in the time dimension, which can more efficiently capture spatiotemporal information. Meanwhile, CNN can capture salient features from the multi-feature and multi-time-step data of the original input. Subsequently, the salient features extracted are combined with the initial input using the residual structure before being fed into the IndRNN module. A case study is conducted on the flight data of two civil aircraft engines to verify the effectiveness of IndRNN compared to traditional RNN. The proposed CNN-IndRNN model can accurately predict the EGT of aircraft engines, with a mean absolute relative error below 1.0%.
Experimental and numerical study of a fluidic oscillator frequency domain characteristics
Authors: Wu Xiyun , Li Kuo , Cao Dalu , Pi Kaiwen 
Published: May 2024

Abstract
Fluidic oscillators are fluid devices that provide steady flow at the inlet while generating unsteady flow at the outlet. This paper aims to investigate the frequency domain characteristics of internal pressure fluctuations in a specific type of fluidic oscillator to gain a deeper understanding of its dynamic behavior. The following conclusions were drawn: (1) Within a certain range, as the inlet-to-outlet pressure ratio increases, the oscillation frequency of the fluidic oscillator continuously rises, and the oscillation amplitude strengthens. (2) As the jet nozzle velocity increases within a certain range, the jet oscillation frequency exhibits a linear upward trend. These research findings provide essential academic and engineering guidance for designing and applying fluidic oscillators, assisting engineers in better understanding and controlling the device’s performance to meet the requirements of various application domains.