bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Study On Aerodynamic Characteristics Of Supersonic Nozzle In Presence Of Ground Effect
Authors: Shi Yalin , Chen Lingling , Chen Pengfei , Yang Qingzhen , Shi Yongqiang , Yang Hua 
Published: April 2022

Abstract
The aeroengine mobile test bench is well applied as it is convenient for outfield transportation and installation, and also it is suitable for different environments. When utilizing a mobile test bench, the distance between the center of the engine and the ground is normally within a range so that it can be manually operated. However, this limited distance will lead to the ground effect, which affects the test performance of the aeroengine.
This paper numerically studies the aerodynamic characteristics of a supersonic nozzle in the presence of the ground effect. The work is conducted with the software package ANSYS Fluent 21, employing the unsteady large eddy simulation. The nozzle works in a supersonic condition, and the distance between the nozzle and the ground is 2Dj. Dj is the diameter of the nozzle outlet. The models with and without ground effect are investigated. The analysis of the flow field confirms that the ground effect enhances the mixing of the jet and the air, and enriches the coherent structure. With the ground effect, the Reynolds stress on the vertical centerline on each section plane is increased, and the shear layer on each section plane is expanded radially. The results show that the ground effect increases the ground temperature after x/Dj=9, shortens the length of the core area by about 12.5%, decreases the mean axial velocity on the centerline of the jet after x/Dj=10, and increases the dimensionless velocity on the near ground side of the vertical plane. Here, x is the distance between the inlet plane and the discussed cross section. The analysis of the thrust characteristics confirms that the ground effect has no influence on the thrust. Therefore, the mobile test bench can accurately evaluate the thrust performance of an aeroengine.
Analysis of double nut installation technology based on new anti loosening performance evaluation test method
Authors: Liu Xiaoyu , Zhang Aixuan , Zhang Zhongwei , Liu Kai , Chen Weiliang , Sun Wendong 
Published: April 2022

Abstract
This paper analyzed the torque combination mode of double nut installation, and two common installation methods are tested and verified by using a new anti loosening performance evaluation method. This method can evaluate the anti loosening performance of small size bolts below M5. Through the test, it is found that when the installation torque of upper and lower nuts is different, the anti-loosening performance of double nuts is better than that of upper and lower nuts with the same mounting torque. It is found that there is a certain dispersion in the anti-loosening performance of double nuts, It is analyzed that the reason for this phenomenon is the difference of product quality. It is proposed to evaluate the quality consistency of fastener products through the dispersion degree of torque coefficient K, and a method to determine the installation torque through the angle torque curve is given.
Design of spaceborne self-closed loop extensible temperature control system based on FPGA
Authors: Huang Yi , Wang Lei , Gu Chenyue , Li Xiaoqing , Wan min , Cheng Guimei 
Published: April 2022

Abstract
The paper describes the design method and implementation of a self-closed loop extensible temperature control system for spaceborne based on FPGA. FPGA is used as the core of data processing System. Firstly using the high accuracy AD and analog switch for temperature data collection. The FPGA is to filter data by average calculation, voltage correction algorithm and PWM controlling temperature algorithm. Finally, after processing temperature control parameters, according to the corresponding channel relation it outputs temperature control parameters to the corresponding control output on NMOS. It can be uploaded temperature threshold parameters through SPI bus, and the corresponding relationship parameters between temperature control and temperature measurement can be modified, and it carry out the remote sensing function on the earth. The system can realize multi-system cascade temperature control through Rs422 bus. This process realizes a complete self-closed loop process, and finally achieves the system design goal.
Crack detection of bushing joint lug based on synthetic aperture fully focused phased array
Authors: He Xiao , Ning Ning 
Published: April 2022

Abstract
In service aircraft, the joint is a key part of the aircraft structure, which needs to bear huge loads. Once cracks occur, it will harm the safety of the overall structure of the aircraft. ABUQUS analyzes the stress concentration area of the joint with bushing (i.e. the location where cracks are easy to occur), and proposes a synthetic ultrasonic detection method at the opening stage. The acquisition and imaging formula of full-focus series ultrasound was derived, and the test block with artificial notch was prepared to verify the test. The error was compared by comparing the measured value with the real value.
Topology Optimization Design With Addictive Manufacturing Constraints for Centrifugal Impeller
Authors: Liu Sifan , Mi Dong , Wen Changlong , Zheng Yanbing 
Published: April 2022

Abstract
Weight reduction of centrifugal impeller is of great significance for improving thrust-weight ratio of aero-engine. In this paper, the weight reduction design for a centrifugal impeller considering additive manufacturing constraints was carry out. First of all, reducing the structure weight by using the topology optimization method based on variable density method. Secondly, reconstructing the results of topology optimization based on the overhang angle, minimum length, connectivity and other additive manufacturing constraints, whose structure contains the self-supporting cavity, oval powder discharge holes and annular convex plate. Finally, adjusting the reconstructed model by using size optimization, which obtained an innovative hollow centrifugal impeller with both lightweight and high mechanical performance. The results indicate that the mass of the optimized centrifugal impeller reduces by 18.5% compared with the original model at the same stress level. The method and scheme can provide reference for the structural optimization design of aero-engine centrifugal impeller.
Vibration Attenuation Performance of Meta-lattice Sandwich Structures with Truss-cores
Authors: Xu Lanhe , Cao Xuche , Cui Xinbo , Li Bing 
Published: April 2022

Abstract
In recent years, lattice sandwich structures with truss-cores have shown great potential in lightweight, high load-bearing and multifunctional applications. However, there is still a lack of research on the vibration attenaution characteristics of such structures. In this paper, combined with the design concept of elastic metamaterial with the lattice truss-core sandwich structures, a meta-lattice sandwich structure with double-layer pyramidal truss core is proposed to realize superior vibration attenuation performance. Theoretical and numerical investigations are conducted on the bandgap mechanisms of the proposed meta-lattice structures. The efficient vibration suppression within the bandgap range is verified by numerical simulations. The results of this paper are of reference value for the design and engineering application of the lattice truss structure for vibration attenuation.
The Modular Relative Orbit Design Method for Spacecraft Proximity Motion
Authors: Wu Lijun , Zhong Weichao , Li Wenlong , Yu Haiyong , Zhang Hao 
Published: April 2022

Abstract
This paper presents a modular relative motion trajectory design tool for proximity operation of on-orbit service spacecrafts. First, a series of commonly used relative motion trajectories are defined. The dynamics are solved such that each type of trajectory is encapsulated into different modules. The input parameters of each module include the key geometrical features, such as the initial position, desired final position, and flying time. Different modules are connected via the same position and velocity. The modular orbit design tool is able to cover most of the typical proximity operation scenarios. Following that, two notational on-orbit service missions are given as examples to describe the specific usage process of the tool. It includes three major steps, namely, determining the appropriate module sequence according to the mission requirements, designing the pending input parameters of each module by taking consideration of constraints, and computing the details of module sequence to generate relative trajectories. Compared with the traditional maneuver-optimized orbit design approach, the modular method has fewer parameters to solve. Additionally, the modular application tool is versatile and can be used for a variety of different on-orbit service missions. This tool is of great importance in standardizing the space operations.
Design of GNSS Receiver Autonomous Integrity Monitoring Platform under Ionospheric Scintillation
Authors: Liu Qi , Zhong Lunlong , Zhao Jing 
Published: April 2022

Abstract
How to evaluate the impact of ionospheric scintillation on the availability of RAIM technology is a key problem to be solved in the field of global satellite navigation system (GNSS) security applications. Based on the relationship between ionospheric scintillation and satellite navigation signal parameters, a scheme of RAIM technology monitoring platform for satellite navigation receiver under ionospheric scintillation is proposed. Firstly, the phase screen model is used to simulate the GNSS satellite navigation signal affected by ionospheric scintillation. Then, the key module of GNSS receiver autonomous integrity monitoring platform under ionospheric scintillation is designed. Simulation results show that the designed platform can effectively simulate satellite navigation signals under ionospheric scintillation and test the effectiveness of various RAIM technology.
Research on Fatigue Characteristics of Bonding interface of Solid Rocket Motor Propellant
Authors: Qu Kai , Xu Xue-wen , Li Jin-fei , Lu Wei-wei 
Published: April 2022

Abstract
With the continuous expansion of the combat mission of the Chinese Navy, the solid rocket motor will be on duty at sea for a long time. During the service period of solid rocket motor, the bonding interface will bear a large number of cyclic fatigue loads. According to the design test, the influence of the strain amplitude and frequency of loading on the bonding interface was studied. The results show that the cyclic loading frequency made no difference on the cyclic damage number in the high frequency. The natural logarithm of the cyclic loading times and cyclic loading accord with linear fitting equation.
Uncertainty Analysis of multi-site damage Crack Propagation Based on the Monte Carlo Method
Authors: Jia Baohui , Xiao Haijian , Fang Jiachen , Shan Zezhong 
Published: April 2022

Abstract
Widespread fatigue damage is one of the main damages of aging aircraft structures, and the problem of multi-site damage has always been a research hotspot in engineering analysis. The traditional probabilistic model for calculating the growth rate of multiple cracks takes into account the multiple uncertain parameters that affect each other’s cracks. However, when solving the multi-site damage (MSD) crack growth problem, the traditional random model needs to solve multiple nonlinear equations. This method becomes no longer applicable. Based on the statistical point of view, this study gives the mutual influence factors of the crack growth process in the form of distribution, and then calculates the probability density function of the crack length under different cycles by sampling with the Monte Carlo (MC) method. Finally, compared with the experimental data, the results show that the calculation results of this method are more accurate and are in good agreement with the experimental data. This method is feasible and accurate for multi-crack propagation analysis of random parameter structures.
Simulation on geometric morphology of multi-channel deposition in laser wire additive manufacturing
Authors: Guo Chuang , Long Jiangqi 
Published: April 2022

AbstractIn multi-channel deposition of laser wire additive manufacturing, to obtain the deposited parts with flat geometric morphology, the deposition process of multi-channel involves the remelting and fusion of the current and the previous channel, and the lap ratio greatly affects the geometric morphology of multi-channel. To study the effect of lap ratio on multi-channel geometric morphology, experiment and numerical simulation were carried out, and the flatness of geometric morphology was taken as the evaluation index. The results show that with the increase of lap ratio, the gap between channels is gradually filled, the pits are gradually smaller, and the geometric morphology tends to be flatter. When the lap ratio exceeds the optimal lap ratio, the latter layer deposits too much on the former one and the height of the deposit will gradually increase, forming slope-like deposited parts.
Improved Aircraft Flared Tube Defect Detection Algorithm of YOLOv4 Network Structure
Authors: Zhang Jian , Wei Siwen , Qi Ming , Wang Pengfei 
Published: April 2022

Abstract
When detecting aircraft flared tube defect with the YOLOv4 network structure, tiny object defects will be missed, and resulting in a high missed detection rate and low mAP (mean Average Precision) value. This paper proposes an improved aircraft flared tube defect detection algorithm of YOLOv4 network structure. Firstly, in order to improve the feature extraction capability of the YOLOv4 network for tiny defects, a convolution operation is added to the SPP (Spatial Pyramid Pooling) and PANet (Path Aggregation Network) structure. Secondly, the representation of the feature pyramid is enhanced utilizing the improved PANet. Thirdly, the decoupled head is utilized to improve the model performance. Finally, we construct the aircraft flared tube dataset by labeling the defect samples, and experiment with the improved YOLOv4 network. Experimental results show that the mAP value of defect detection task is increased from 91.26% to 95.31%, average detection time increased from 346.17ms to 278.61ms.
Research on target detection method based on CNN
Authors: Niu Wei , Gao Bo , Zhan Wentao , Cheng Juan 
Published: April 2022

Abstract
Traditional target detection methods have poor tracking effect for targets with excessive displacement or occlusion between adjacent frames, and it is difficult to deal with high-speed moving targets. In view of the low detection rate of the current system in detecting long-distance weak and small targets, false targets and occlusion in the air, the working mode of convolutional neural network (CNN) and its advantages in target detection are analyzed, and a target detection method based on CNN is proposed, which can ensure the target detection accuracy and meet the real-time requirements of combat scenes, Finally, compared with other algorithms, the proposed method achieves the best results on four types of data. While the center error is low, it has high tracking success rate and low time complexity, which meets the requirements of high precision and real-time of the system.
Real-Time Analysis and Research of Vehicle CAN
Authors: Zhang Lin-rui , Xiao Jun , Zhang Xu-guang , Zhang Wei-wei 
Published: April 2022

Abstract
The real-time evaluation method of CAN bus is studied. The event-triggered CAN protocol has no limitation on the worst transmission time of information. Based on the study of ratio monotone analysis (RMA), a single step recursive relation equation is deduced. Using LabWindows /CVI design and analysis software, the research method is applied to offline realtime analysis of CAN bus information of a certain vehicle. The results show that this method is of great significance to the real-time evaluation of CAN bus.
Research on Demonstration and Validation of Space Rapid Response Launch System based on Data Link
Authors: Wu Feng , Zhang Ailiang , Liu Xiuluo , Wang Jia , Wang Min 
Published: April 2022

Abstract
The demonstration and verification of space rapid response launch system based on data link mainly combines with the process, style and characteristics of space rapid response launch, through construction the typical mission scenarios by simulation, carries out design and verification of wide-area maneuver anti-interference networking technology system between platforms such as space and ground data link nodes, container launcher and micro-nano satellite systems, research and design of formatting message standard system, etc., to promote the integrated application of data link and space rapid response launch equipment, so as to enhance command and control, situation sharing and tactical coordination capabilities.
Numerical Simulation and Aerodynamic Investigation of the Intermeshing Rotor in Hover
Authors: Gao Zeming , Li Jun , Shao Xueming , Zeng Lifang 
Published: April 2022

Abstract
Compared with single rotor helicopter, aerodynamic theoretical model for intermeshing rotor is immature. Aerodynamic modeling for intermeshing rotor is much more complex because of the strong and unsteady interference resulting from two closely rotating blades. Moving Overset Grid technical has been used for the aerodynamic investigation of intermeshing rotor in hovering state. SST k - ω turbulence model was used for the solving of unsteady RANS equations. The simulated result matches well with the experimental data, in which the calculation error for lift coefficient, Ct
, is smaller than 4.5%. Firstly, the fluctuation of Ct
is periodic with a frequency of 4/rev, which is equal to the total number of blades of the intermeshing rotor. Average aerodynamic loads rise as the increasing of collective angles. Secondly, the maximum induced velocity of the intermeshing rotor is significantly larger than those of the single rotor and the equivalent rotor. Blade-vortex interference and vortex-vortex interference coexist in the flow field of the intermeshing rotor. Finally, three shaft angles, 20°, 24°, 28°, were investigated. Among the calculating cases, the effect of the shaft angles is not monotonous. Maximum hovering efficiency is achieved at θ = 24°.
Research on Cooperative Search Trajectory Planning for Rotorcraft UAVs Based on Scrolling Planning Algorithm
Authors: Zhuang Yufeng , Xu Jianfeng , Wang Li 
Published: April 2022

Abstract
The UAV trajectory planning algorithm for scrolling planning is proposed for the objective of multi-UAVs searching for multiple targets in an uncertain environment. Information about the unknown environment is described using infographic, while for the huge computational effort in multi-UAVs scrolling planning, an improved genetic algorithm is used to solve the optimal solution for the UAV population. Simulation results show that the scrolling planning algorithm proposed in this paper can achieve a better search for the target in the uncertain region, and the algorithm framework is reasonable and feasible with high planning efficiency, which can be used for the cooperative search task of multi-UAVs in the uncertain area.
Research on Comparative Monitoring Method of Aerodynamic Coefficient Applied to Artificial Ice Flight Test
Authors: Xu Zeqian , Chen Junping 
Published: April 2022

Abstract
In the implementation of the artificial ice flight test, artificial ice shapes must be installed to the test aircraft, which reduces the aerodynamic performance of the aircraft and leads to a high risk. In order to reduce the risk of artificial ice flight test, starting from the flight test requirements, this paper proposes a real-time comparative monitoring scheme of the design lift coefficient and the actual lift coefficient of the test aircraft, and develops a comparison model of aerodynamic coefficients accordingly. Verified by the flight test data, the model can figure out reasonable design lift coefficient and actual lift coefficient, which lays a foundation for the subsequent application in the artificial ice flight test.
A heterogeneous redundancy method for flight control computer based on mutual exclusion and spin mechanism
Authors: Chen Chang , Yang Xueqi , Zhang Jing , Xu Shunfan , Chai Xudong , Hong Yan 
Published: April 2022

Abstract
In order to meet the requirements of high reliability and economy of space launch vehicle control system, a heterogeneous redundancy method of flight control computer based on mutual exclusion and spin mechanism is proposed in this paper. This method avoids common cause failure mode and improves hardware resource utilization efficiency by resolving redundancy. The reliability and economy of the launch vehicle control system can be improved without increasing the cost of volume and weight.
Prediction of aircraft engine parameters based on ARMA model
Authors: Qu Youyang 
Published: April 2022

Abstract
The high-pressure rotor speeds, low-pressure rotor speeds, and exhaust temperature of the aircraft engine are the key parameters reflecting the performance of aircraft engines. To realize the trend monitoring during the flight test and the processing of data outliers in flight data recorder, the time series analysis and modeling method is used to establish a suitable ARMA model through data processing, series property analysis, model identification, order determination, modeling, model diagnosis and other steps. Fit the real flight test data of an engine. The results show that the prediction interval within 3 steps of the ARMA model has high accuracy, and has good engineering practicability in real-time flight monitoring and data processing.
Asymmetrical cooling effects of Amazonian protected areas across spatiotemporal scales
Authors: Huang Anqi , Xu Xiyan , Jia Gensuo , Shen Runping 
Published: April 2022

Abstract
Amazonian protected areas (PAs) play an important role in maintaining the regional and global ecosystem services, biodiversity and climate change mitigation. The effects of Amazonian PAs on climate change mitigation mainly focus on the carbon sequestration benefits. The biophysical effects of PAs on regulating the local energy budgets, and hence changing local climate, however, are often ignored. Using multiple satellite observation datasets, we evaluated the effects of Amazonian PAs on land surface temperature (LST) and the biophysical mechanisms of PAs on surface albedo and evapotranspiration (ET). We showed that Amazonian PAs have a cooling effect on local LST in relative to nearby croplands and non-protected areas (non-PAs) with the same land cover as PAs. The asymmetrical cooling effects of Amazonian PAs between daytime and nighttime, and between the dry and wet seasons sustain lower diurnal and seasonal temperature ranges, respectively, than non-PAs and croplands. The protected forests have stronger cooling effects, and more effectively moderate the diurnal and seasonal temperature ranges than the protected savannas due to the higher effects on surface albedo and ET. The non-PAs show weaker cooling effect than PAs, indicating reduced thermal buffering effect in non-PAs. Our results highlighted the great potential of natural vegetation in PAs versus non-PAs and croplands in buffering local thermal environment and the necessity of natural vegetation conservation in Amazon region.