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6th China Aeronautical science and technology Conference, CASTC 2023

作者： Xie, Wujun Min, Liwu Li, Jun Li, Hui Key Laboratory of Science and Technology on Life-Support Technology AVIC Aerospace Life-Support Industries Ltd. Hubei Xiangyang China

ISBN: (纸本)9789819988600

During ejection rescue, the parachute gun attached to a rocket-assisted ejection seat generates jet noise that may damage a pilot’s sensitive auditory organs;hence the effectiveness of hearing protectors, primarily a helmet and earmuffs, is evaluated. A parachute gun firing experiment is designed, and overpressure data with and without protection are measured simultaneously during firing using piezoelectric pressure sensors inside and outside dummy ears. A comparative study of the measured data is conducted using time domain analysis and wavelet transformation methods, and the results show that the jet noise generated by a parachute gun firing is a broadband signal, consisting of shock waves and impulse noise;different from the attenuation characteristics in the continuous noise environment, in the jet noise environment, the effect of hearing protectors is significant for extenuating the high-frequency components that are prone to injury, but not significant for extenuating the low-frequency components. © 2024, Chinese Society of Aeronautics and Astronautics.

关键词： Time domain analysis

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Study on Simulation Method to Determine the Inflation Threshold of Head Protective Airbag for High-speed Helicopter Pilot 2

Study on Simulation Method to Determine the Inflation Thresh...

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2022 2nd International Conference on Mechanical, Aerospace, and Automotive Engineering, CMAAE 2022

作者： Feng, Zhijie Fan, Chengcheng Ke, Chuanyi Zhang, Haibo Liu, Tao AVIC Aerospace Life-Support Industries LTD. Xiangyang441000 China Aviation Key Laboratory of Science and Technology on Life-Support Technology Xiangyang441000 China School of Aerospace Engineering Tsinghua University Beijing100084 China

Compared with ordinary helicopters, the flying speed of high-speed helicopters is increased from 350km / h to 450km / h, and the crash speed is bound to exceed 12.8m / s, which greatly increases the probability of collision injury of the pilots' head. The equipment, such as the traditional safety belts and crashworthy seats, cannot play an effective role in protection. In order to effectively improve the crashworthy survival rate of high-speed helicopter pilots, the main method in European and American countries is to design additional head protective airbags. The paper carried out the study on the simulation method for determining the high-speed helicopter head protection airbag inflation threshold value. Based on LS-DYNA, it has established the impact simulation model of the high-speed helicopter cockpit - seat - safety belt - pilot system. At the same time, the HIC value of the dummy head (no more than 1000N) and the pull force of the shoulder strap (no more than 8890N) are taken as the objective function to simulate the collision process of the man/seat system in multiple states of the high-speed helicopter. Finally, the inflation threshold of the head protective airbag is determined, which provides a critical support for the development of the head protective airbag. © Published under licence by IOP Publishing Ltd.

关键词： Helicopters

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Simulation study on dynamic opening characteristics of airplane drag chute under the condition of stable crosswind

Simulation study on dynamic opening characteristics of airpl...

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CSAA/IET International Conference on Aircraft Utility Systems 2020, AUS 2020

作者： Jin, Lou Yang, Pin Hu, Xuepeng Li, Hui Zhang, Linling Cui, Dongyue Aviation Key Laboratory of Science and Technology on Life-support Technology Xianyang China AVIC Aerospace Life-support Industries Ltd. Xianyang China AVIC The First Aircraft Institute Institute of Mechanical and Electrical System Xi'an China

ISBN: (纸本)9781839535635

In this paper, the ALE fluid-solid coupling algorithm is used to realize the simulation of the dynamic opening process of a certain type of airplane drag parachute. Based on the drag parachute working principle and folding process, a finite element model of the main parachute in the installed state is established. In the LS-DYNA software, the parachute opening characteristics of the drag parachute were simulated and analyzed under no crosswind conditions and Stable crosswind conditions at speed 10m/s. The results show that, under the condition of no crosswind, the error of the important parameters such as parachute straightening force, parachute opening dynamic load, parachute deflection angle and test data is less than 15%, and the simulation accuracy meets the engineering development requirements. On this basis, the parameters such as the unfolding shape, deflection angle, and stress state of the parachute parachute under stable crosswind conditions, which are difficult to test and simulate, were studied. This will provide a theoretical basis and technical approach for drag chute design and other types of parachute product research. © 2020 Institution of Engineering and technology. All rights reserved.

关键词： Product design

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Neural-activity-regulated and glia-mediated control of brain lymphatic development

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Cell 2025年

作者： Li, Jia Liu, Ming-Jian Du, Wen-Jie Peng, Xiao-Lan Deng, Hao Zi, Hua-Xing Shang, Han-Bing Du, Jiu-Lin Institute of Neuroscience Key Laboratory of Brain Cognition and Brain-Inspired Intelligence Technology Center for Excellence in Brain Science and Intelligence Technology Chinese Academy of Sciences Shanghai 200031 China University of Chinese Academy of Sciences Beijing 100049 China Department of Neurosurgery Ruijin Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200025 China Department of Anesthesiology Huashan Hospital Fudan University Shanghai 200040 China Emergency Medicine Center Shanghai Institute of Aviation Medicine Ruijin Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200025 China School of Life Science and Technology ShanghaiTech University Shanghai 200031 China Department of Neurosurgery Huashan Hospital Fudan University Shanghai 200040 China

The nervous system regulates peripheral immune responses under physiological and pathological conditions, but the brain's impact on immune system development remains unknown. Meningeal mural lymphatic endothelial cells (muLECs), embedded in the leptomeninges, form an immune niche surrounding the brain that contributes to brain immunosurveillance. Here, we report that the brain controls the development of muLECs via a specialized glial subpopulation, slc6a11b+ radial astrocytes (RAs), a process modulated by neural activity in zebrafish. slc6a11b+ RAs, with processes extending to the meninges, govern muLEC formation by expressing vascular endothelial growth factor C (vegfc). Moreover, neural activity regulates muLEC development, and this regulation requires Vegfc in slc6a11b+ RAs. Intriguingly, slc6a11b+ RAs cooperate with calcium-binding EGF domain 1 (ccbe1)+ fibroblasts to restrict muLEC growth on the brain surface via controlling mature Vegfc distribution. Thus, our study uncovers a glia-mediated and neural-activity-regulated control of brain lymphatic development and highlights the importance of inter-tissue cellular cooperation in development. © 2025 Elsevier Inc.

关键词： development fibroblast immune system leptomeninges meningeal mural lymphatic endothelial cells nervous system neural activity radial astrocyte VEGFC

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Research on Reliability Assessment Method of Emergency Escape Parachute 5

Research on Reliability Assessment Method of Emergency Escap...

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2020 5th International Conference on Intelligent Computing and Signal Processing, ICSP 2020

作者： Ma, Fangyun Lei, Huajin Wang, Wensheng Liu, Jing Jin, Liying Aviation Key Laboratory Science and Technology on Life-Support Technology Hubei Xiangyang441003 China Aerospace Life-Support Industries Ltd. Hubei Xiangyang441003 China School of Mechanical Engineering Hubei University of Arts and Science Xiangyang441053 China

Aiming at the problem that emergency escape parachute cannot meet the requirements of the index using the binomial evaluation method, combined with the characteristics of emergency escape parachute products, comprehensively using emergency escape parachute components and system test data, the emergency escape parachute Bayesian reliability assessment method is proposed to solve the problem of reliability assessment in the case of small sample size of emergency escape parachute system test, which effectively reducing emergency escape parachute test expenses and development cycle. © 2019 Published under licence by IOP Publishing Ltd.

关键词： Parachutes

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Research on residual design of ignition circuit of ejection seat 24

Research on residual design of ignition circuit of ejection ...

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5th International Conference on Computer Information and Big Data Applications, CIBDA 2024

作者： Wang, Wensheng Wu, Shuanglong Li, Jin Jin, Liying Aviation Key Laboratory Science and Technology on Life-Support Technology Xiangyang Hubei441003 China Aerospace Life-Support Industries Ltd. Xiangyang Hubei441003 China Xiangyang Key Laboratory of Intelligent Manufacturing and Machine Vision Hubei University of Arts and Science Hubei Province Xiangyang441053 China

ISBN: (纸本)9798400718106

At present, the programmed ignition circuit is used in the ejection seat to stimulate the explosive materials. This paper analyzes the ignition circuit architecture of the parachute projectile fired by the electric detonator on the ejection seat, and puts forward two other feasible ignition schemes. Combined with the task reliability block diagram and model, the three schemes are respectively quantitatively calculated and qualitatively analyzed, thus the optimal fire scheme is determined. Then it provides a reference for the redundancy design of other parts of the ejection seat. © 2024 ACM.

关键词： Ejection seats

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Equivalent study on delethalization test for sled head injury criteria test of civil aircraft passenger seat

Equivalent study on delethalization test for sled head injur...

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CSAA/IET International Conference on Aircraft Utility Systems 2020, AUS 2020

作者： Jin, Zhi-Sheng Shen, Wen-Bo Luo, Guo-Xiong Li, Ming Jia, Zhi-Xiao Zhou, Wu Jia, Luo Zhang, Le Aviation Key Laboratory of Science and Technology on Life-Support Technology Xiang yang China Test Department AVIC Aerospace Life-Support Industries Ltd No.29 Xinhua road Xiang yang China Science and Technology Development Department AVIC Aerospace Life-Support Industries Ltd No.29 Xinhua road Xiang yang China

ISBN: (纸本)9781839535635

The equivalent study between delethalization test and sled HIC test is in order to improve the efficiency of Head Injury Criteria (HIC) test on civil aircraft passenger seats, as well as to reduce the test consumption and cost. The equivalent impact model was established based on the equal rotatory kinetic energy, then the test of equal energy impact was designed and the delethalization test was carried out. The results of delethalization test and sled HIC test show that all the deviation value of HIC, peak head center of gravity (CG) acceleration in X direction, peak head CG resultant acceleration and the deformation of the seat back (C/B) was within ± 20%. In conclusion, the equivalent impact model in this paper is suitable, and the delethalization test be used as an equivalent method for sled HIC test is feasible. © 2020 Institution of Engineering and technology. All rights reserved.

关键词： Kinetics

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A Health Assessment Strategy for Helicopter Emergency Floatation System

A Health Assessment Strategy for Helicopter Emergency Floata...

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International Conference on Guidance, Navigation and Control, ICGNC 2020

作者： Ding, Qiyan Sun, Zhi Cheng, Lihong Lu, Ningyun Jiang, Bin College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing210000 China Key Laboratory of Aircraft Environment Control and Life Support MIIT Nanjing University of Aeronautics and Astronautics Nanjing210016 China Aviation Key Laboratory of Science and Technology on Life-Support Technology Xiangyang441003 China

ISBN: (纸本)9789811581540

When taking salvaging missions, helicopters play important roles but still face high risk because of complex circumstance. Emergency Floatation System (EFS) is critical to ensure flight safety and conduct emergency rescue for helicopters. To achieve this goal, the reliability of EFS itself is the first concern during its design and development. This paper presents a health assessment strategy for EFS of helicopters, based on multi-signal flow graph modeling, fault tree based diagnosis and Bayesian Networks (BN) based assessment. The simulation results can show that the developed strategy is feasible to evaluate the health status of EFS, which will be helpful for the maintenance division to take proper precautions to avoid potential accidents. © 2022, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Bayesian networks

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Numerical investigation of influence of structure and operating parameters on performance of vortex oil filter

Numerical investigation of influence of structure and operat...

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CSAA/IET International Conference on Aircraft Utility Systems, AUS 2018

作者： Wang, Ning Chen, Weijian Ning, Guoli Hui, Ma Key Laboratory of Aircraft Environment Control and Life Support MIIT Nanjing University of Aeronautics and Astronautics Nanjing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing China

ISBN: (纸本)9781785617911

In this paper, the three-dimensional numerical simulation of solid-liquid two-phase flow in a vortex oil filter is performed by means of numerical simulation. The Reynolds stress turbulence model is used in the simulation flow field, and the DPM model is used for solid particle tracking. The influence of key structural parameters and operating parameters on the filtering effect was mainly studied, such as the inlet width, the size of the overflow pipe, the wall thickness and the insertion depth, the size of the cone angle and the length of the cone end. The results provide the basis for the rational design of the vortex oil filter. © 2018 IET Conference Publications. All rights reserved.

关键词： Vortex flow

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NUMERICAL SIMULATION OF IMPACT OF EJECTION SEAT ROCKET MOTOR IGNITION SHOCK WAVES ON AIRCRAFT WINDSHIELD LOADING

NUMERICAL SIMULATION OF IMPACT OF EJECTION SEAT ROCKET MOTOR...

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2024 CSAA/IET International Conference on Aircraft Utility Systems, AUS 2024

作者： Wu, Liang Jin, Lou Xu, Hang Wu, Yibin Overall Technology R&D Department AVIC Aerospace Life-support Industries Ltd. Xianyang441000 China Aviation Key Laboratory of Science and Technology on Life-support Technology Xianyang441000 China Ejection Lifesaving Technology R&D Department AVIC Aerospace Life-support Industries Ltd. Xianyang441000 China

Aircraft windshield fragmentation during seat ejection can adversely affect crew ejection from the aircraft safety. In this paper, the shock wave loads caused by the firing of an ejection seat rocket motor were simulated numerically, and the numerical simulation flow was designed with the dynamic grid technique. The results show that the pressure peak of the inner surface monitoring point at the front end of the windshield is 9.4% lower compared with the test value at the same location when the rocket engine is firing at 0 km/h velocity ejection, which proves the numerical simulation method feasible. The effects of rocket pack ignition shock waves on the aircraft windshield can be divided into shock wave loading phase and quasistatic pressure loading phase. The former has a large peak load and a short duration, while the latter has a small peak load and a long *** corners within the cockpit, converging phenomena occur during shock wave propagation, and the area near the cabin inner wall at the front and sides of the aircraft's windshield is more heavily loaded and has a higher risk of damage than other areas. The moment of maximum windshield loading for each calculated state is the moment of the first load peak. Due to the high velocity airflow blowing effect, the maximum windshield loading at 1100 km/h ejects is close to the zero velocity ejection value, acting in the opposite direction. The zero velocity ejection and impact loads at 1100 km/h eject should be emphasized in the windshield strength analysis. © The Institution of Engineering & technology 2024.

关键词： Ejection seats

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