bluuebunny/crossref_metadata_2025 huggingface dataset:
ROS-responsive celastrol-nanomedicine alleviates inflammation for dry eye disease
Authors: Cui Bingbing , Zhang Nan , Zhang Wei , Ning Qingyun , Wang Xing , Feng Huayang , Liu Ruixing , Li Zhanrong , Li Jingguo
Published: June 2024

Dry eye disease (DED) is a major global eye disease leading to severe eye discomfort and even vision impairment. The incidence of DED has been gradually increasing with the high frequency of use of electronic devices. It has been demonstrated that celastrol (Cel) has excellent therapeutic efficacy in ocular disorders. However, the poor water solubility and short half-life of Cel limit its further therapeutic applications. In this work, a reactive oxygen species (ROS) sensitive polymeric micelle was fabricated for Cel delivery. The micelles improve the solubility of Cel, and the resulting Cel loaded micelles exhibit an enhanced intervention effect for DED. The in vitro results demonstrated that Cel-nanomedicine had a marked ROS responsive release behavior. The results of in vitro and in vivo experiments demonstrated that Cel has excellent biological activities to alleviate inflammation in DED by inhibiting TLR4 signaling activation and reducing pro-inflammatory cytokine expression. Therefore, the Cel nanomedicine can effectively eliminate ocular inflammation, promote corneal epithelial repair, and restore the number of goblet cells and tear secretion, providing a new option for the treatment of DED.
Time-domain diffuse optical imaging technique for monitoring rheumatoid arthritis disease activity: theoretical development and in silico validation
Authors: Ioussoufovitch S , Diop M
Published: June 2024

Objective. Effective early treatment—within 3–5 months of disease onset—significantly improves rheumatoid arthritis (RA) prognosis. Nevertheless, 1 in 3 patients experiences treatment failure which takes 3–6 months to detect with current monitoring techniques. The aim of this work is to develop a method for extracting quantitative features from data obtained with time-domain diffuse optical imaging (TD-DOI), and demonstrate their sensitivity to RA disease activity. Approach. 80 virtual phantoms of the proximal interphalangeal joint—obtained from a realistic tissue distribution derived from magnetic resonance imaging—were created to simulate RA-induced alterations in 5 physiological parameters. TD-DOI images were generated using Monte Carlo simulations, and Poisson noise was added to each image. Subsequently, each image was convolved with an instrument response function (IRF) to mimic experimental measurements. Various spatiotemporal features were extracted from the images (i.e. statistical moments, temporal Fourier components), corrected for IRF effects, and correlated with the disease index (DI) of each phantom. Main results. Spatiotemporal Fourier components of TD-DOI images were highly correlated with DI despite the confounding effects of noise and the IRF. Moreover, lower temporal frequency components (

⩽

0.4 GHz) demonstrated greater sensitivity to small changes in disease activity than previously published spatial features extracted from the same images. Significance. Spatiotemporal components of TD-DOI images may be more sensitive to small changes in RA disease activity than previously reported DOI features. TD-DOI may enable earlier detection of RA treatment failure, which would reduce the time needed to identify treatment failure and improve patient prognosis.
Bias correction for phase-based cr-MREPT using low resolution B1+ magnitude
Authors: Çan Mustafa Kaan , Ider Yusuf Ziya
Published: June 2024

Objective Full-form Magnetic Resonance Electrical Properties Tomography (MREPT) requires both

B
1
+

magnitude and phase information. Since

B
1
+

phase can be obtained faster and with higher SNR compared to

B
1
+

magnitude, several phase-based methods have been developed for conductivity imaging. However, phase-based methods suffer from a concave bias due to the assumption that

∇

|

B
1
+

|

is negligible in the ROI. Approach In this paper, we re-derive the central equation of phase-based cr-MREPT without assuming that

∇

|

B
1
+

|

is negligible and thus propose a correction method directly integrated into the equation system. Main results Proposed method successfully corrects the concave bias on both simulated and experimental data and significantly increases image quality. Significance The proposed correction method depends on a very low-resolution

|

B
1
+

|

map, and therefore the imaging time does not increase significantly for obtaining

B
1
+

magnitude. Moreover, correction can be achieved using simulated

B
1
+

magnitude, hence completely removing the additional imaging requirement.
JET far-infrared interferometer/polarimeter diagnostic system—40 years of lessons learned
Authors: Boboc A , Macdonald J , Felton R , Brown M J , Studholme W , Cramp S ,   the JET Operations Team
Published: June 2024

Originally designed for 5 years of plasma operations, the JET far infrared interferometer/polarimeter diagnostic system was still operating at full capability nearly 40 years later in ITER-relevant conditions (e.g. metal wall, tungsten divertor) for multiple D–T campaigns, albeit with significantly lower neutron fluences. The original design had to be adapted substantially over the years due to machine changes, leading to reduced signal and access to mirrors etc, and the diagnostics still worked due to the excellent dynamic range of the detectors. This paper will discuss invaluable lessons learned from designing, operating, optimising and enhancing such a complex system and how these can be used for developing a new class of laser-based diagnostics for next-generation reactor-grade machines.
Winding angle optimization and testing of small-scale, non-planar, high-temperature superconducting stellarator coils
Authors: Huslage P , Kulla D , Lobsien J-F , Schuler T , Stenson E V
Published: June 2024

We designed and constructed two non-planar coils with high-temperature superconductors (HTS) based on shapes from the Wendelstein 7-X stellarator. Tape track orientation of the HTS was optimized to reduce the coil size as much as possible while staying within the strain limits of the gadolinium barium copper oxide (GdBCO) superconductor. This resulted in average coil radii of 0.23 m and 0.48 m at strain limits of up 0.45% to for the coil shapes that were chosen. The coils were produced by winding the GdBCO tapes onto 3D-printed plastic frames. We confirmed the integrity of the superconducting layer after winding by spatially resolved measurement of the critical current and by energizing the coils in liquid nitrogen. Coil 1 showed a resistance of

1.75

μ
Ω

and did not have any critical current degradation, while coil 5 had a resistance of

195

μ
Ω

and showed only one dropout, attributable to a handling error. We measured the magnetic field of the coil with a three-axis Hall probe system and found good agreement with predictions. This work demonstrates the manufacturing of small-scale, non-planar magnetic coils from commercially available HTS.
Electron capture and excitation in intermediate-energy He2+–H(1s,2s) collisions
Authors: Liu 刘 Yadong 亚东 , Jia 贾 Congcong 聪聪 , Ma 马 Mingxuan 茗萱 , Gao 高 Xiang 翔 , Liu 刘 Ling 玲 , Wu 吴 Yong 勇 , Chen 陈 Xiangjun 向军 , Wang 王 Jianguo 建国
Published: June 2024

The semiclassical non-perturbative atomic orbital close-coupling approach has been employed to study the electron capture and excitation processes in He2+–H(1s) and He2+–H(2s) collision systems. In order to ensure the accuracy of our calculated cross sections, a large number of high excited states and pseudostates are included in the expansion basis sets which are centered on the target and projectile, respectively. The total and partial charge transfer and excitation cross sections are obtained for a wide-energy domain ranging from 1 keV/amu to 200 keV/amu. The present calculations are also compared with the results from other theoretical methods. These cross section data are useful for the investigation of astrophysics and laboratory plasma.
HiFAST: An H i Data Calibration and Imaging Pipeline for FAST. II. Flux Density Calibration
Authors: Liu Ziming , Wang Jie , Jing Yingjie , Zhang Zhi-Yu , Xu Chen , Liang Tiantian , Chen Qingze , Tang Ningyu , Yang Qingliang
Published: June 2024

Accurate flux density calibration is essential for precise analysis and interpretation of observations across different observation modes and instruments. In this research, we first introduce the flux calibration model that incorporated in HiFAST pipeline, and designed for processing H i 21 cm spectra. Furthermore, we investigate different calibration techniques and assess the dependence of the gain parameter on the time and environmental factors. A comparison is carried out in various observation modes (e.g., tracking and scanning modes) to determine the flux density gain (G), revealing insignificant discrepancies in G among different methods. Long-term monitoring data shows a linear correlation between G and atmospheric temperature. After subtracting the G–Temperature dependence, the dispersion of G is reduced to <3% over a one-year timescale. The stability of the receiver response of Five-hundred-meter Aperture Spherical radio Telescope (FAST) is considered sufficient to facilitate H i observations that can accommodate a moderate error in flux calibration (e.g., > ∼ 5%) when utilizing a constant G for calibration purposes. Our study will serve as a useful addition to the results provided by Jiang et al. Detailed measurement of G for the 19 beams of FAST, covering the frequency range 1000–1500 MHz, can be found on the HiFAST homepage: https://hifast.readthedocs.io/fluxgain.
Long-term Variation of the Solar Polar Magnetic Fields at Different Latitudes
Authors: Yang Shuhong , Jiang Jie , Wang Zifan , Hou Yijun , Jin Chunlan , Song Qiao , Luo Yukun , Li Ting , Zhang Jun , Zhang Yuzong , Zhou Guiping , Deng Yuanyong , Wang Jingxiu
Published: June 2024

The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind. However, because our view of the Sun is limited in the ecliptic plane, the polar regions remain largely uncharted. Using the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 2021, we investigate the long-term variation of the magnetic fields in polar caps at different latitudes. The Hinode magnetic measurements show that the polarity reversal processes in the north and south polar caps are non-simultaneous. The variation of the averaged radial magnetic flux density reveals that, in each polar cap, the polarity reversal is completed successively from the 70° latitude to the pole, reflecting a poleward magnetic flux migration therein. These results clarify the polar magnetic polarity reversal process at different latitudes.
Heat and particle exhaust in high-performance plasmas in Wendelstein 7-X
Authors: Gao Yu , Geiger Joachim , Jakubowski Marcin W. , Pandey Arun , Bozhenkov Sergey , Feng Yuhe , Endler Michael , Baldzuhn Jürgen , Perseo Valeria , Kremeyer Thierry , Schlisio Georg , Puig Sitjes Aleix , Otte Matthias , Naujoks Dirk , Krychowiak Maciej , König Ralf , Zhang Daihong , Szepesi Tamás , Kocsis Gábor , Cseh Gábor , Buzás Attila , Pisano Fabio , Knieps Alexander ,   the W7-X Team
Published: June 2024

The paper reports for the first time the heat and particle exhaust at the plasma boundary through various edge diagnostics for the high-performance plasma obtained after pellet injection on Wendelstein 7-X. The plasma density at the edge is found to be reduced by a factor of 2 in the high-performance phase, supporting the previously reported density peaking at the plasma centre. The plasma beta effect on the magnetic topology is reflected by the appearance of the second strike line, which is well understood with simulation. However, during the rapid decay phase of the enhanced confinement, a transient localized heat flow of up to 16 MW m−2 is observed at the leading edge of a poorly cooled divertor component, which has not been understood but raises concerns about machine safety.
RSU-Net: An Attention U-Net for Martian Rock Segmentation
Authors: Tian Pengzhi , Yao Meibao
Published: June 2024

Since rocks may collide with the rover or wear tires during the exploration mission of the Mars probe, and may contain rich geological information, identifying rocks in the scene is crucial for the navigation and obstacle avoidance of the Mars probe. Additionally, since the communication between the Mars rover and the earth is often intermittent and delayed during missions, it needs a certain degree of autonomy. Deep learning technologies such as semantic segmentation and target detection can meet this requirement to a certain extent, which facilitates the enhancement of safety and efficiency for the Mars rover. Rock segmentation is to divide the pixels of the rock from the image. However, the texture of the rock is often close to the texture of the surrounding sand, and some parts may be covered, so it is difficult to identify it correctly. To this end, this paper proposed RSU-Net (Rock Segmentation U-Net) and RSU-Net-L, which combine the SENet attention mechanism, and the latter achieves higher computational efficiency and inference speed by compressing the number of channels on the basis of the former. In addition, this paper established a dataset, MarsRock, for Mars rock segmentation to help the Mars rover for visual navigation. Its images come from “Tianwen-1”, which contains 1194 images, and each image has a corresponding rock label. And our experiments on the MarsRock dataset show that RSU-Net can achieve 99.07% accuracy and 67.71% F1-score. RSU-Net-L can achieve 98.99% accuracy and 66.67% F1-score while diminishing the number of parameter count by 43.7% and the number of FLOPs by 43.6%, while the FPS can reach 12.01 on a single RTX6000-24GB GPU.
Fast 3D Reconstruction for Unknown Space Targets via Neural Radiance Field
Authors: Lu Chenxi , Yu Meng , Cui Hutao
Published: June 2024

In this study, a novel residual space object 3D model reconstruction approach is proposed. First, several low-cost CubeSats are assigned to carry out multi-view image capture in the vicinity of the space target, yielding a series of images with relative pose information. Then, a fast 3D reconstruction approach based on NeRF is introduced, in which real-time performance and reconstruction quality are improved for fast on-board 3D reconstruction. Finally, a simulation test is designed to verify the performance of the proposed method, results show that the proposed NeRF-based method is superior to traditional method in terms of reconstruction speed and texture richness.
Optimization Design of Mechanical Properties of Frame Plate Structure for Aircraft Repair Based on Genetic Algorithm
Authors: Meng Xiangrui , Ma Yongbin , Guo Ziwen , Fan Junling , Deng Zichen
Published: June 2024

Designing options for aircraft frame plate repair often relies on experience. Development of optimization technique is necessary to obtain optimal design for aircraft frame plate structure. In this paper, a method to optimize the repair parameters using genetic algorithm is proposed for the structural repair of aircraft frame plate. In the design process, the parameters of the reinforced piece are considered, including the type, length, width, thickness, and the layout of the rivets. Compared with the traditional genetic algorithm, the algorithm based on this paper considers the crossover between species and so on, so it can find the optimal solution in a wider design space. The finite element software ABAQUS combined with Python tool is used for parametric modelling and calculation, and the residual stress values of the repaired part is used as the objective function. Finally, a repaired aircraft frame plate structure with best static and dynamic properties is obtained.
An Inductance-Capacitance Measurement Method Based On Auto-Balancing Bridge
Authors: Liu Kang , Zhou Chengning , Chen Xueying , Wang Fu
Published: June 2024

Modern measurement modules are extremely demanding on the hardware and must accurately capture the relevant parameters of capacitance and inductance. The inductance and its quality factor, capacitance and its loss angle tangent value are very important parameters, but also the current testing difficulties. To efficiently and accurately measure the inductance and its quality factor, capacitance and its loss angle tangent, this paper developed a capacitance-inductance testing method based on automatic balanced bridge circuit. Firstly, based on the DSP development board, test capacitance and inductance by switching dip switches; Then, the use of self-excited oscillation method to generate a fixed frequency sinusoidal signal, through the amplifier to increase the amplitude of its signal, and the use of adder to the signal to provide a certain bias to meet the amplitude requirements; Finally, based on the automatic balanced bridge method, through the full-wave rectification plus filter will be converted into the average of the signal to be tested, and then use the amplifier circuit to control the average value of the signal to be tested, and then use the amplifier circuit to control the average value. Then use the amplifier circuit to control the average value within the AD sampling range, and use the micro-controller to collect the test amplitude, phase and other related parameters. The test results show the effectiveness of the proposed method.
Active Packet Dropout Kalman Filter Based Diagnosis Scheme For Liquid Rocket Engines With Measurement Fault
Authors: Zhang Zhenzhen , Zhang Xiaoguang , Chen Hui , Ma Meng
Published: June 2024

Various faults of the liquid rocket engine (LRE) threaten the safety of space launches. The LRE system faults are challenging to detect and isolate owing to sensor faults. In this paper, an active packet dropout Kalman filter (APD-KF) based method is proposed for solving the problem of LRE system fault detection and isolation (FDI) under measuring fault. Sensor faults are isolated firstly based on distributed extended multiple model adaptive estimation (EMMAE) scheme, and the sensor fault detection isolation (FI) result are then transformed to the package drop matrix and inserted into the system fault factor estimation process to discard fault measurement information. Experimental results based on data from simulation are used to decorate the efficiency of the method. This study may help to improve LRE health management and reduce launch risk by solving the problem of LRE system FDI with measurement fault.
Numerical study on ultrasonic detection of cracks in metallic structures with variable cross-sectional thickness
Authors: Wang Yan , Feng Rongxin , Hameed Muhammad Saqib , Zhang Shuai , Xu Jifeng , Zheng Kaihong
Published: June 2024

The metal structures are widely used in aerospace engineering, especially in joints and spars. The safety of these parts is important to ensure the safe service of the whole structures. The ultrasonic wave is a traditional technique to detect cracks in metals. However, it is usually difficult to find all the cracks because of its difficulty in variable directions of the crack and the irregular shapes of the metals. This paper aims to address the challenge of detecting cracks in metallic structures with varying cross-sectional thicknesses using ultrasonic methods. The research investigates the behavior of ultrasonic longitudinal and transverse waves as they propagate through aluminum plates with variable cross sections. Additionally, it examines how cracks in different orientations influence these wave types. The theoretical analyses are performed which explore the reflection of oblique incidence waves and the diffraction of ultrasonic waves when they encounter semi-infinite cracks. Subsequently, numerical simulations are performed to validate the theoretical findings and to detect both horizontal and vertical cracks within metal plates of varying cross-sectional thicknesses. The findings indicate that both longitudinal and transverse waves are effective in identifying the location of damage caused by horizontal cracks. However, when it comes to vertical cracks, only transverse waves are successful in detecting their precise location. From the research of this paper, transverse ultrasonic wave is suggested to detect cracks in metal structures with irregular cross sections.
Research on Load Control Of Main Bearing Based on Isfd Principle
Authors: Wang Ye , Guo Jie , Sun Xiewen
Published: June 2024

The main bearing load of the internal combustion engine is one of the main excitation sources that cause the vibration and radiation noise of the body structure. By reducing the main bearing load transmitted from the main bearing cap to the body, the vibration and noise of the internal combustion engine can be effectively reduced. In this paper, the main bearing cap damper is designed based on the principle of integral squeeze film damper (ISFD), and the load is controlled on the transmission path of the main bearing load. The main bearing load measurement scheme is designed. The load changes of the main bearing cap before and after the installation of the main bearing cap damper are measured experimentally. The load control effect of the main bearing cap damper is analyzed and verified.
Dynamic Simulation Analysis of Aviation Gear Transmission Based on Rough Tooth Surface
Authors: Sun Xiewen , Wei Huirong , Wang Ye
Published: June 2024

In order to explore the influence of tooth surface microstructure on the dynamics of aviation gear transmission, this paper describes the profile of aviation gear considering rough surface based on fractal theory. With the help of the established gear fractal contact model, the dynamic parameters such as time-varying friction coefficient, time-varying meshing stiffness and transmission error of rough tooth surface are characterized. The nonlinear dynamic model of aviation gear is established to solve the dynamic response of smooth and rough tooth surface. The dynamic meshing force, dynamic friction force, vibration time domain and frequency domain diagram are obtained, and the corresponding experiments are carried out. The simulation and experimental results show that the fluctuation range of the dynamic simulation results of aviation gear transmission based on rough tooth surface will be larger, and it has a certain degree of disorder, which is closer to the experimental results.
Drive Control Technology of Dual Three Phase Permanent Magnet Synchronous Motor for Electric Propulsion Aircraft
Authors: Kuang Zhi , Wang Yining , Duan Xiaoli , Wu Donghua , Cui Shumei
Published: June 2024

Green aviation is one of the effective ways to cope with future oil energy shortages and improve the atmospheric environment. As the executing mechanism of electric propulsion aircraft, the fault tolerance and safety of the electric drive system are the primary considerations. This article uses dual three-phase permanent magnet synchronous motors (PMSM) to drive propellers to provide power for electric propulsion aircraft. Firstly, the working principle of the propellers is analyzed, and a simulation model of the propellers is established using Simulink; Secondly, the space vector control method of dual three-phase PMSM is elaborated, and two different forms of space vector control are compared. At the same time, a vector control model of dual three-phase PMSM is established, and the third harmonic content of dual three-phase PMSM under two different space vectors is compared through simulation. Finally, establish a simulation model of dual three-phase PMSM driving propeller, compare the motor phase current and driving performance of different vector control methods, and analyze the advantages and disadvantages of different vector control methods.
Optimization design of rotor system with squeeze film damper
Authors: Shengxi Jia , Junyi Chen , Mi Yan , Hao Zhang , Xiaotao Tian
Published: June 2024

For the rotor system with squeeze film damper (SFD), an optimization design method based on eccentricity iteration was proposed. In this method, ANSYS is used to calculate the dynamic characteristics of the rotor, and Isight is used to solve the optimization design problem. The position of bearing, the position of disks and the support stiffness of SFD was selected as design variables. The optimization design of a double-disk flexible rotor system with SFD was performed, and a series of comparative experiments were carried out. The experimental results show that: after optimization, the amplitude response of the two disks is only 0.052 mm and 0.08 mm respectively when the rotor system passes through the critical speed, and the reaction response of the two supports is only 35 N and 34.2 N respectively. The experimental results demonstrate the effectiveness of the method. It can be used as a general method to deal with the engineering problems of optimal design of complex rotor system with SFD. The optimal design result of the rotor system is that the stiffness of the elastic support is reduced to the minimum, and the position of the two disks is close to the support on the premise that the critical speed satisfies the constraint.
Minimum nonprobabilistic entropy deconvolution for fault diagnosis of rolling element bearings
Authors: Zhu Yuanhang , Zi Yanyang , Chen Zhenyi , Shi Zhen , Zhao Yuhao
Published: June 2024

The blind deconvolution methods (BDMs) is one of the most common methods for fault diagnosis of rolling bearings, and it is essential to maintain the safe and reliable operation of mechanical equipment. However, noise interference and the need for prior periods limit the scope of application of the BDMs. In this paper, a new minimum nonprobabilistic entropy deconvolution (MNPED) method is proposed. According to the correlation between fault impact and non-Gaussianity, the Gaussian membership function in fuzzy set theory is used to map the sample points to the membership degree of Gaussian distribution, and then the nonprobabilistic entropy (NPE) is formed to measure the impact characteristics of the signal. Then NPE is incorporated into the iterative process of solving the filter coefficient. Finally, the target signal and the optimal filter coefficient are selected based on the criterion of minimum NPE. MNPED is capable of adaptively extracting the periodic pulse of a signal without requiring prior knowledge of the period, even in the presence of strong noise interference. The effectiveness and robustness of the proposed approach are validated through simulation and experimental data.
Numerical simulation and experimental analysis of foreign object impact on aero-engine fan rotor blade
Authors: Zhang Shuai , Dong Jiang
Published: June 2024

The detection and identification of fan rotor foreign object impact events during the working process of aero-engines are crucial to the safety and security of aircraft flight. Through the numerical simulation method based on finite element and the foreign object impact test platform to simulate the process of real engine impact by foreign objects, the rule of fan rotor blade foreign object impact and the monitoring and identification method were studied. Meanwhile, aiming at the problems of high difficulty and low accuracy in identifying the impact of foreign objects on the fan by the airborne parameters and added vibration parameters, the non-contact vibration measurement method based on blade tip timing was used to obtain the blade vibration displacement under different fan speed, foreign matter mass and impact velocity. The numerical simulation and experimental results show that the change trend of the vibration displacement of the rotor tip of the fan is consistent with that of the numerical simulation. And with the increase of the foreign object projectile mass, the vibration displacement of the blade tip caused by the impact of the foreign object on the fan blade increases. In addition, the impact velocity of the foreign object has little effect on the vibration displacement of the blade tips after impact. Furthermore, the vibration displacement of the blade tip caused by the impact of foreign objects first increases and then decreases with increasing speed.
Development of a mathematical model for the prediction of drill quality in voice-activated ultrasonic vibration assisted drilling process.
Authors: Bhuiyan Shah Alam , Patwari Anayet U , Navid Wasib Ul , Morshed Rahman Maruf , Showkhin Sakib
Published: June 2024

In different industries, drilling quality play an important role in the success of operations by producing millions of quality drilled parts. The production of high-quality parts at the lowest possible cost to the manufacturer is the primary goal of contemporary process and assembly industries. To assess the quality index of drilling holes; circularity index and surface roughness are important metrics. In order to produce better drilled parts at lower prices, this study work attempts to determine the key process variables using voice acting modules to investigate the induced vibrations effects that have the greatest impact on surface roughness and circularity index in a vertical CNC drilling machine. In order to forecast the surface roughness and circularity index of drilled holes within a given operational range, a mathematical model has been proposed by adopting a coupled algorithm using design expert and statistical approach. As an experimental design technique, Response Surface Methodology with small central composite design is used to enable the evaluation of various process parameters related with machining and vibration parameters and their effects on surface roughness and circularity index. The created model is improved using statistical tools to ensure the best match to the experimental data. It has been observed with the increase of RPM and vibration frequency the surface roughness increases up to a certain limit and then decrease whereas with the increase feed the surface roughness increases. But in terms of circularity index with the increase of the process parameters the plotted graph trends under perturbation analysis shows the similar pattern CI decreases up to a certain limit and then increases.
Study on bearing capacity and damage mode of carbon fiber composite J-type structures in oilfield completion tool connections
Authors: Lu Daosheng , Sun Yongtao , Zou Wei , Cheng Wenjia
Published: June 2024

Carbon fiber composite structures have a broad application prospect in oilfield completion tool module connection. However, the material failure mechanism is still unclear. In this paper, the mechanical properties and failure mode of T700/7901 composite J-type structure are investigated from experimental and finite element perspectives. Firstly, the load-carrying and failure properties of the structure were analyzed through typical mechanical property experiments such as tensile, bending, and compression, and the fiber, matrix damage, and delamination damage are the main reasons for the failure of the mechanical properties of the material. Secondly, a numerical model of the progressive damage ontological relationship of the composite material was established, and the accuracy of the model was verified by combining the experimental results. Based on the above study, this paper proposes the failure mechanism and optimization of composite J-type, which provides useful guidance for the design of fiber composite structures for oilfield completion tool types in the future.
Study on mechanical properties of bolted connection structure of carbon fiber resin matrix composites at low temperature
Authors: Ren Xiaoyang , Li Xiaoming , Huang Heyuan
Published: June 2024

This article focuses on the impact of low temperature environments that composite materials may face in engineering applications. Through experimental testing, the bearing capacity of carbon fiber resin based composite bolted structures at -100 ℃ and 25 ℃ was obtained, and a continuous damage model (CDM) was established. The damage evolution mechanism of bolted connection structures between metal and carbon fiber resin matrix composites at -100 °C and 25 °C was elucidated through numerical simulation. Research has shown that the ultimate load of the structure at -100 °C is 3.99% lower than that at room temperature, and the failure mode of the composite material structure at low temperature is transverse fracture along the hole edge, which is different from the compression tensile fracture along the nail hole section at room temperature.
Design and Implementation of Simulation Training System for Ground Maintenance Pannel of a Certain Type of Aircraft
Authors: Wang Yizun , Zhou Qiting
Published: June 2024

According to the design requirements of ground maintenance pannel simulation training system of a certain type of aircraft, a set of training system with the functions of ground handling practice, aircraft maintenance operation training and PMA interactive operation training is developed. The system design fully considers the requirements of generalization and modularization design. The function division of each module is clear, the signal interface is clear, and one of the modules can be replaced quickly to facilitate the positioning and elimination of failure. It has the dual expansibility of training task and training model, and can continuously add training task package, including procedure training, troubleshooting guidance training, etc., and can adapt to change in aircraft state.
Remaining Useful Life Prediction Of Precision Bearing Based on Multi-Head Attention Mechanism
Authors: Guo Fan , Niu Hongwei , Li Ming
Published: June 2024

The high-precision bearing is the core component of the space actuator, whose remaining useful life (RUL) prediction is an essential issue of constructing condition-based maintenance (CBM) system. To address the current challenges of establishing traditional physical failure models for high-precision bearings and dealing with long time-series vibration data, this paper proposes a precision bearing remaining useful life prediction model based on multi-head attention mechanism. The model utilizes a one-dimensional convolutional neural network (CNN) to compress the input features along the time dimension, then, an encoder-decoder architecture with a multi-head attention mechanism for further feature exploration. Experiments are conducted using vibration signals from the IEEE PHM 2012 Challenge dataset for training and validation. The results indicate that this algorithm exhibits relatively smaller relative errors compared to other algorithms, demonstrating good accuracy and strong stability. This approach shows promise in accurate and reliable precision bearing life prediction.
MCSA-based fault diagnosis for rotary parts in servo motion system: Approach and experimental study
Authors: Liu Hanyang , Sheng Feng , Lu Xinyu , Lin Jing
Published: June 2024

Motor current signature analysis (MCSA), as a non-invasive diagnostic method, is robust to environmental noise and of less sensor cost than vibration-based monitoring. Although large amount of progress has been achieved, little attention is paid to the MCSA-based diagnosis task in the Servo motion systems (SMS). An approach using Park vector demodulation, comb filtering and the ensemble empirical mode decomposition (EEMD) is proposed for cyclic fault event detection in this paper. Experiment studies reveal that the MCSA approach could extract the fault signature under extremely low-speed or noisy working condition, which has potential in the scenarios where the accelerometers placement is limited or affected by interferences.
Research on bearing fault diagnosis based on laser vibrometer
Authors: Chen Xueying , Jiang Zhaoxiang , Zhou Chengning , Liu Caixue , Yang Taibo
Published: June 2024

As general components in machinery, rolling bearings are also fault prone components. And unexpected faults will bring immeasurable loss to economy, personnel, etc. Therefore, fault detection and diagnosis are of paramount importance. As the carrier of fault information, component response signal is the most concerned part in fault diagnosis researches. The detection methods for response signal can be divided into contact and non-contact detection. Compared with the contact detection, laser Doppler vibrometer has the advantage of no contact, no damage and dynamic measurement. Thus, this paper progresses theoretical and experimental researches on non-contact detection of bearing wear fault based on laser Doppler vibrometer. Firstly, the vibration measurement principle of laser Doppler vibrometer is analyzed in this paper. On account of the principle, the internal optical path and signal flow of the single point laser vibrometer is established and analyzed. Secondly, in order to carry out the non-contact detection test, an optical measuring system based on a single point laser vibrometer is built to collect signals. Also, a bearing wear fault simulated test rig is built to provide fault response signals. Based on the above built test devices, the detection tests of the intact and faulty bearings are carried out. Lastly, through the analysis of collected signals of bearings with wear of different parts in time domain and frequency domain, the characterizations of the corresponding fault are obtained so as to implement the fault diagnosis, which prove the effectiveness of laser vibration detection method for fault detection.
A Method for Continuous Observation of Sea Surface Moving Targets Based on Multi Point Trajectory Prediction
Authors: Ren Xupu , Cheng Yao , Li Yuqing
Published: June 2024

The detection and tracking of sea surface sensitive targets are challenging due to their high manoeuvrability and the limited field of view of low-orbit remote sensing satellites. This paper presents a prediction model for the trajectory of moving targets on the sea surface, which utilizes a dynamic and variable potential target area and transition probability density function by using prior information, such as the position, speed, and course of a moving target when observed. When a moving target is observed multiple times, its velocity is estimated using the least squares method and the Kalman filtering algorithm, while its course is predicted using Hermite interpolation polynomials. Simulation examples are used to validate the feasibility and effectiveness of the proposed approach.
An Analytical Method for Accuracy Analysis of Close Proximity Rendezvous in Space Based on an Improved C-W Equation under Perturbation Effects
Authors: Duan Qinzheng , Gao Yu , Li Yuqing
Published: June 2024

In order to address the issue of quantitatively solving the impact of perturbation forces and initial errors on rendezvous accuracy, traditional analytical methods are not suitable, and the calculation steps for statistical methods based on Monte Carlo simulation analysis are complex and computationally time-consuming. To overcome these challenges, this paper proposes a method for analysing rendezvous accuracy based on an improved relative motion dynamics model. Describing the relative motion between a sub-spacecraft and a target spacecraft by an improved Clohessy-Wiltshire (C-W) equation. By employing the derived state transition matrix from the model, it is possible to calculate the error propagation during the rendezvous process and express the rendezvous accuracy analytically. Through simulation examples, the proposed method proves to be both accurate and efficient in analysing the influence of perturbation forces and random errors such as initial position and velocity on rendezvous accuracy. This study verifies the correctness and effectiveness of the approach.
Research on Spacecraft Fault Diagnosis and Recovery Architecture
Authors: Cheng Yao , Gong Ying , Wang Jingyan , Xiong Xiao
Published: June 2024

Fault diagnosis and recovery system is designed to monitor on-orbit state of spacecraft and handle exception, which provides spacecraft security and missions succeed. This report studies the design of spacecraft fault diagnosis and recovery system from technology and architecture two respects. Technical system and modules design from top level for spacecraft fault diagnosis and recovery is proposed. And the architecture of comprehensive fault diagnosis system is also proposed, which supports spacecraft to diagnose and recover on-orbit faults.
A Multi-satellite Scheduling Method for Emergency Observation Mission Based on Hierarchical Planning Strategy
Authors: Huang Lixia , Zhao Xuemei , Zhang Qiang , Li Qunzhi
Published: June 2024

Emergency observation tasks involve Earth imaging activities by satellites to aid in emergency scenarios like disaster relief, emphasizing promptness and unpredictability. Multi-satellite collaborative planning for several emergency tasks faces issues like high computational complexity, slow processing, and numerous optimization considerations. This paper introduces a hierarchical planning approach and designs an algorithm for collaborative task planning across multiple emergencies and satellites. The algorithm’s computational efficiency and planning effectiveness are later confirmed through a case study.
Attitude control of combined spacecraft with fuzzy neural network disturbance observer
Authors: Sun Yicheng , Li Xiaoyue , Fu Yichuan , Lyu Yueyong
Published: June 2024

A finite-time control strategy based on a fuzzy neural network disturbance observer (FNNDO) and nonsingular terminal sliding mode (NTSM) is proposed for the attitude control system of a combined spacecraft in the presence of non-cooperative targets with competitive torque output. First, a mathematical model of the combined spacecraft attitude is established with the service spacecraft as the reference. Then, the external disturbances and competitive torque output from non-cooperative targets are treated as generalized disturbances, and FNNDO is employed for tracking and compensation. Subsequently, a NTSM controller is designed to achieve finite-time attitude takeover control of non-cooperative targets. The stability of the disturbance observer and controller is proven using Lyapunov stability theory. Simulation results demonstrate that this control strategy effectively handles the competitive actions of non-cooperative targets while rapidly stabilizing the combined spacecraft’s attitude at the desired values.
Design of Improved Ground Closed-loop Test System Based on Variable-stability Flight Control Computer
Authors: Yahui Hu , Wei Fang , Ertai Cao
Published: June 2024

With the development of civil aviation, ground simulation test has gradually become a key link in the transformation of basic theory to engineering application. By forming a closed-loop link between the variable stability aircraft (VSA) dynamics model and the aircraft rudder surface, sensors, etc., the variable-stability ground closed-loop test system can simulate the aircraft flight state and response characteristics in the ground environment. However, the current ground test system suffers from a wide range of signals, complex signal simulation methods, and low system integration. In this study, an improved modular ground closed-loop test system for VSA is designed from three aspects: signal acquisition and simulation of airborne equipment, parameter monitoring and data processing, and fault simulation subsystem, which improves its compatibility and integrates with the software hardware of the variable-stability flight control computer and other air-borne equipment. After the system interconnection test, the generalized ground closed-loop test system designed in this study can replace the original system more efficiently, and its signal connection has inheritability, and provides a design method reference for other related researches of the variable-stability flight control computer.
Model Predictive Control with Gaussian-Process-Enhanced Dynamics for Spacecraft Attitude Takeover Maneuvers
Authors: Liu Yuhan , Wang Pengyu
Published: June 2024

This paper aims to deal with the attitude takeover control for combined spacecraft with unknown dynamics and attitude maneuverability of the target. Generally, the dynamics of combined spacecraft executing an on-orbit servicing task is highly nonlinear and costly to identify. To address this issue, a sparse variational Gaussian process (GP)-based model predictive control (MPC) strategy is proposed to achieve efficient attitude takeover maneuvers under multiple constraints and target attitude maneuverability. The GP regression performs a model completion behavior, where the unknown dynamics is compensated by the sparse variational GP with a low computational load. This enhances the control performance of the combined spacecraft during the takeover task execution. Numerical simulations are used to demonstrate the effectiveness of the proposed strategy.
Air-Ground Characteristic Test and Analysis on Fan Blade Vibration Stress of Turbofan Engine
Authors: Tao Ye
Published: June 2024

Obtaining the vibration stress of fan rotor blades under actual working conditions through flight tests is a necessary means to carry out design verification and optimization improvement of turbofan engine. Taking the high bypass ratio turbofan engine as research object, installed ground and flight tests were carried out. The vibration characteristics and stress distribution of the fan blade were obtained by direct measurement means of strain gauge, and the air-ground characteristics of the test data were compared and analyzed. The results show that under the steady state, the vibration stress level of fan blade in ground test is significantly higher than that in flight test; There is a significant difference in frequency distribution of excitation factors on fan blade in the ground and flight tests.
A Framework for FDM-based DFAM: Key Enabling Technologies for Knowledge-based Design
Authors: Haruna Auwal , Noman Khandaker , Li Yongbo , Shah Intizar Ali
Published: June 2024

The booming and evolution of additive manufacturing (AM) technologies call for robust key enabling technologies and solutions to the ongoing advancement of AM. However, there are limitations to the fused deposition modeling-based design for AM (FDM-based DFAM), including an inadequate understanding of the process activities and the progressive industrialization, which make the concept generation operations unreliable, inconsistent, and of limited influence. This paper proposes a principle knowledge-based framework for enabling technologies in FDM-based DFAM to provide solutions to the abovementioned engineering problems to increase the viability of industrial applications. Consequently, a case study application is used to verify the feasibility and effectiveness of our approach.
A boundary condition-damping spring for simulating the acoustoelastic effects of Lamb waves
Authors: Tao Tang , Zhigao Xu , Jiazhao Chen , Yuxiang Zhang
Published: June 2024

Physical field simulation is considered an efficient and economical method to study the acoustoelastic effect. Therefore, many researchers thirst for a suitable boundary condition for effectively absorbing incoming waves and reducing echoes while applying pre-stress to the study object, so that the acoustoelastic effects can be more clearly observed by time-domain information of simulation results. However, the existing boundary conditions in physical field simulation software perform helplessly. For this reason, a boundary condi-tion named “damping spring” is proposed in this paper and the corresponding parameter setting scheme is given, effectively solving the above contradiction. Then the feasibility of this boundary condition is verified in 2D and 3D models. In addition, the damping spring boundary condition is applied in this paper to the simulate the acoustoelastic effect of S0-mode Lamb waves in metal plate structures, whose rule shows a good consistency with that of the known literature [5], further verifying the feasibility of the damping spring boundary condition applied to simulate the acoustoelastic effects.