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A Flexible Valve Based Piezoelectric Pump for High Viscosity Cooling Liquid Transportation

Transactions of Nanjing University of Aeronautics and Astronautics 2021年第6期38卷 993-1002页

作者： LI Kai LIU Jiaming ZHANG Quan ZHANG Jianhui HUANG Jun WANG Yuan New Combined Power R&D Center Shaanxi Province Aerospace and Astronautics Propulsion Research Institute Co.Ltd.Xi’an 710003P.R.China Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang 212013P.R.China School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200072P.R.China College of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006P.R.China College of Communication Engineering Army Engineering University of PLANanjing 210007P.R.China

A piezoelectric pump with flexible valve has been developed to pump high viscosity cooling liquid in the nanosats thermal control system. The structure of the flexible valve is designed according to the characteristics of the human aortic shape with the aim to simulate the bionic pumping function of the human heart. Dynamic stress-strain features of the flexible valve are analyzed by the finite element method,and the results show that the proposed flexible valve is suitable and functional for the piezoelectric pump. Then the cylinder and diffuser/nozzle piezoelectric pumps based on flexible valves have been developed and fabricated. Experimental results of the output performance indicate that the maximum flow rate of the cylinder piezoelectric pump with flexible valve is 15.38 mL/min,170.77% higher than the diffuser/nozzle piezoelectric pump with flexible valve. The ability of the cylinder piezoelectric pump with flexible valve for transmitting high viscosity liquid has been validated. The piezoelectric pump with flexible valve has potential applications in the nanosats thermal control system.

关键词： piezoelectric pump high viscosity liquid flexible valve cut-off performance pumping performance

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Impact of Thickness in Ultra-Thin Ald-Processed HfO2 Gate Dielectric on the Performance of Low-Operating Voltage Thin-Film Transistors

SSRN

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SSRN 2024年

作者： Chen, Minyu Chen, Huimin Solano, Eduardo Merino, Danile Hermida Hua, Wenqiang Ding, Xingwei Wei, Bin Liao, Yingjie Wu, Bing Microelectronic R&D Center School of Mechanical & Electronic Engineering and Automation Shanghai University Shanghai200072 China Key Laboratory of Advanced Display and System Applications Ministry of Education Shanghai University Shanghai200072 China Laboratory CNRS ERL 7004 University of Technology of Troyes 12 rue Marie Curie Troyes10004 Cedex France NCD-SWEET beamline ALBA Synchrotron Cerdanyola del Vallès Barcelona08290 Spain Shanghai Advanced Research Institute Chinese Academy of Sciences 201210 China 71 Avenue Des Martyrs CS 40220 Grenoble38043 France Magnetic Resonance Research Center Institute for Molecules and Materials Radboud University Nijmegen Netherlands

The effective reduction in the thickness of the metal gate while retaining its defect-free morphology and high dielectric properties is of great interest for producing low-power-consumption and high-performance thin film transistors (TFTs). In this study, a series of ultrathin hafnium dioxide (HfO2) coating layer with different thickness were prepared by atomic layer deposition (ALD) as TFT dielectrics. In XPS analyses, it was observed that the ratio of HfOx to HfO2 decreases with the increasing thickness of the HfO2 layer. Concurrently, the ratio of O species outside HfO2 also decreases as the thickness of the HfO2 layer increases. These HfO2 films were further examined by grazing incidence small and wide-angle x-ray scattering (GISAXS/GIWAXS), atomic force microscope (AFM) and X-ray to understand the impact of these films’ thickness on their morphological and topological properties. Afterwards, the dielectric properties of all these films were analyzed by the impedance measurement, it was found that the optimized 10 nm HfO2 thin film can exhibit a low-leakage current density of 13 nA cm−2 at 1 V and a permittivity of 5.98. Finally, the as-fabricated ZnO TFT with a 10 nm HfO2 gate dielectric layer was found to be able to operate at an ultra-low voltage of -1.59 V with a very high current on/off ratio, which is larger than 106. This result demonstrates the critical importance in controlling the thickness of dielectric layer to achieving high-performance TFTs and its profound potential in the applications of low-power consumption microelectronics. © 2024, The Authors. All rights reserved.

关键词： Thin films

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Long-term stability analysis of vertical channel damping and kalman filtering for inertial navigation system/vertical gauge 16

Long-term stability analysis of vertical channel damping and...

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16th International Conference on Electrical engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON 2019

作者： Park, Chan Gook Cha, Jaehyuck Ju, Hojin Automation and Systems Research Institute Seoul National University Department of Mechanical and Aerospace Engineering Seoul08826 Korea Republic of Automation and Systems Research Institute Seoul National University Seoul08826 Korea Republic of

ISBN: (纸本)9781728133614

This paper deals with inertial navigation system (INS) aided by a vertical gauge (VG) for unmanned vehicles in two different schemes, vertical channel damping (VCD) and Kalman filter (KF). As the altitude error of standalone INS goes to diverge quickly, a VG can play a key role in an integrated navigation. A conventional technique to integrate INS with a VG is the VCD scheme which only corrects the vertical channel states by separating them from those of the horizontal channels. On the other hand, in this paper, it is shown that a KF scheme without separation of them can also reduce the horizontal position estimation errors as well by only using a VG. The navigation results of the two different schemes through numerical simulations are compared. Providing the simulation results on the both of correct and incorrect KF measurement error model, it shows the performance of KF scheme considerably depends on the model accuracy. © 2019 IEEE.

关键词： Inertial navigation systems

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Autonomous Base Station Placement for Localization of the GNSS Interference Source

Autonomous Base Station Placement for Localization of the GN...

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2018 International Symposium on Global Navigation Satellite system, ISGNSS 2018

作者： Kim, Sun Young Kang, Chang Ho Park, Chan Gook Mechanical and Aerospace Engineering and Automation and System Research Institute Seoul National University Gawnak-Gu Seoul08826 Korea Republic of BK21+ Transformative Training Program for Creative Mechanical and Aerospace Engineers Seoul National University Gawnak-Gu Seoul08826 Korea Republic of Mechanical and Aerospace Engineering and the Institute of Advanced Aerospace Technology Seoul National University Gawnak-Gu Seoul08826 Korea Republic of

This paper presents the control strategy of autonomous base station placement for localization of the GNSS interference source. The proposed algorithm deals with the optimization of the base station trajectory for target motion analysis based on bearing only tracking problem. The control strategy of the proposed algorithm is designed to maximize a cost function which is generally a functional of the Fisher information matrix. Compared to the optimal control methods, the proposed algorithm is easy to be designed and implemented, and constraints of multiple base stations' trajectories can be effectively included. In addition, the proposed algorithm also considered target's dynamics that is both uncertain and random, and there are multiple base stations for observing the target. In order to verify the performance of the proposed algorithm, simulation was performed with dynamic target case in the 2D scenario. It is assumed that the base stations' networks have non-fully connected topology. According to the simulation results, it was confirmed that the proposed algorithm presents a flexible control strategy of autonomous multiple base stations' placement for bearing only target tracking system. © The Authors, published by EDP Sciences, 2019.

关键词： Base stations

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Dynamic Characteristics of Ball Bearing-Coupling-Rotor system with Angular Misalignment Fault

Research Square

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research Square 2021年

作者： Wang, Pengfei Xu, Hongyang Yang, Yang Ma, Hui He, Duo Zhao, Xiang School of Mechanical Engineering and Automation Northeastern University Liaoning Shenyang110819 China China North Vehicle Research Institute Beijing100072 China Key Laboratory of Vibration Control of Aero-Propulsion System Ministry of Education Northeastern University Liaoning Shenyang110819 China

The rotor misalignment fault, which occurs only second to unbalance, easily occurs in the practical rotating machinery system. Rotor misalignment can be further divided into coupling misalignment and bearing misalignment. However, most of the existing references only analyze the effect of coupling misalignment on the dynamic characteristics of the rotor system, and ignore the change of bearing excitation caused by misalignment. Based on the above limitations, a five degrees of freedom nonlinear restoring force mathematical model is proposed, considering misalignment of bearing rings and clearance of cage pockets. The finite element model of the rotor is established based on the Timoshenko beam element theory. The coupling misalignment excitation force and rotor unbalance force are introduced. Finally, the dynamic model of the ball bearing-coupling-rotor system is established. The radial and axial vibration responses of the system under misalignment fault are analyzed by simulation. The results show that the bearing misalignment significantly influences the dynamic characteristics of the system in the low-speed range, so bearing misalignment should not be ignored in modeling. With the increase of rotating speed, rotor unbalance and coupling misalignment have a greater impact. Misalignment causes periodic changes in bearing contact angle, radial clearance, and ball rotational speed. It also leads to reciprocating impact and collision between the ball and cage. In addition, misalignment increases the critical speed and the axial vibration of the system. The results can provide a basis for health monitoring and misalignment fault diagnosis of the rolling bearing-rotor system. © 2021, CC BY.

关键词： Rotating machinery

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Stereo visual-inertial odometry with an online calibration and its field testing

Stereo visual-inertial odometry with an online calibration a...

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2018 International Symposium on Global Navigation Satellite system, ISGNSS 2018

作者： Jung, Jae Hyung Heo, Sejong Park, Chan Gook Dept. of Mechanical and Aerospace Engineering / Automation and Systems Research Institute Seoul National University Korea Republic of Hanwha Corporation/Defense Korea Republic of

In this paper, we present a visual-inertial odometry (VIO) with an online calibration using a stereo camera in planetary rover localization. We augment the state vector with extrinsic (rigid body transformation) and temporal (time-offset) parameters of a camera-IMU system in a framework of an extended Kalman filter. This is motivated by the fact that when fusing independent systems, it is practically crucial to obtain precise extrinsic and temporal parameters. Unlike the conventional calibration procedures, this method estimates both navigation and calibration states from naturally occurred visual point features during operation. We describe mathematical formulations of the proposed method, and it is evaluated through the author-collected dataset which is recorded by the commercially available visual-inertial sensor installed on the testing rover in the environment lack of vegetation and artificial objects. Our experimental results showed that 3D return position error as 1.54m of total 173m traveled and 10ms of time-offset with the online calibration, while 6.52m of return position error without the online calibration. © The Authors, published by EDP Sciences, 2019.

关键词： Rovers

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Curvature-property coupling governed heat transfer deterioration in supercritical helically coiled tubes: Mechanistic insights and mitigation strategies via structural parametrization

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International Journal of Thermal Sciences 2025年 215卷

作者： Chang, Fucheng Xin, Jiaxing Wu, Xiaoyi Li, Liwei Li, Huixiong Zhu, Yanlin National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China China Special Equipment Testing and Research Institute Beijing100029 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd Shanghai200233 China

The unique thermo-hydrodynamic coupling phenomena in the helically coiled tube (HCT) handling supercritical fluids present both opportunities and challenges for next-generation compact heat exchangers. While the pronounced thermophysical property variations near pseudo-critical temperatures (Tpc) and curvature-induced secondary flows synergistically enhance heat transfer coefficient (HTC), their nonlinear coupling mechanisms may unexpectedly provoke severe heat transfer deterioration (HTD). Through systematic numerical investigations, this study reveals that circumferential wall temperature inhomogeneity (CWTI) exhibits an inverted N-shaped evolution, providing valuable insights for thermal homogenization design near Tpc. The secondary flow Reynolds number (Se), quantifying secondary flow intensity, shows a monotonic increase with decreasing coil diameter (Dc) or inner diameter (Di), reaching saturation in high-enthalpy regions. Notably, CWTI demonstrates non-monotonic behavior, achieving minimum values near Tpc before manifesting distinct rebound characteristics near Tpc conditions. Parametric analysis establishes that: (1) Elevating heat flux (q) increases Se, reducing Dc boosts it by 50.3 %, and decreasing Di raises it by 60.0 %. (2) HTD predominantly initiates at the outer wall under high-q conditions, with Dc reduction achieving HTD suppression and 26.9 % enhancement in the local HTC;(3) Reducing the Di results in a reduction of maximum CWTI by 22.5 %–28.6 %, suggesting that structural parametrization effectively mitigates wall temperature non-uniformity, thus suppressing the HTD. While centered on supercritical water, the dimensionless scaling relationships demonstrate extendibility to other media, with the curvature-property coupling mechanism both elucidating fundamental interactions and guiding robust heat exchanger design. © 2025 Elsevier Masson SAS

关键词： Electric heating

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Investigation of high-tumble chamber of ammonia-hydrogen fueled elliptical rotary engine based on turbulence and combustion characteristics

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Fuel 2025年 400卷

作者： Zhenghao Yang Guangyu Jia Yang Du Ziwen Fang Xu Gao Guangyu He Zhengbiao Wang National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Xi’an Shaanxi 710038 China School of Mechanical Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China Science and Technology on Diesel Engine Turbocharging Laboratory China North Engine Research Institute Tianjin 300400 China

The ammonia-hydrogen dual-fuel elliptical rotary engine (AH-ERE) is a promising novel power system within the low-carbon context. To enhance the combustion and emission performances of AH-ERE, this paper investigates the optimized high-tumble chamber arrangement from both aspects of cylinder configuration (front configuration FC, middle configuration MC, and rear configuration RC) and hydrogen injection angle ( HIA = 0°, 45°, and 60°). On this basis, the characteristics of the flow field and mixture distribution under different operating conditions are compared from the perspective of in-cylinder swirl and tumble flow emphatically. Finally, the improvement of combustion, power and emission performance by cylinder configuration and HIA is analyzed. The results indicate that under MC-A60 condition, the hydrogen jet tends to accumulate inside the external chamber due to the effect of wall blocking and high tumble ratio. This phenomenon significantly promotes the flame propagation, resulting in the highest indicated power of 11.30 kW and NO x emission of 41.07 ppm. As the HIA decreases to 45°, the dispersed combustion caused by long hydrogen penetration distance and high TKE leads to a 55.10 % reduction in NO x , at a slight expense of power performance. In comparison, the RC cylinder has more uniform hydrogen distribution and significant clockwise tumble. The RC-A30 condition can reduce NO x emission to 20.09 % of MC-A60 condition while maintaining the indicated power of 10.87 kW, performing better in terms of emission performance.

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Distributed cooperative guidance for multi-missile system with time-varying delays and switching topologies

Distributed cooperative guidance for multi-missile system wi...

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第三十九届中国控制会议

作者： Siquan Zhou Jie Ren Yong Heng Xiwang Dong Qingdong Li School of Automation Science and Electrical Engineering Science and Technology on Aircraft Control Laboratory Beihang University Beijing Aerospace System Engineering Research Institute Beijing Institute of Electronic System Engineering Beijing Advanced Innovation Center for Big Data and Brain Computing Beihang University

Distributed cooperative guidance problems for multi-missile system with time-varying delays and switching topologies are investigated. Firstly, considering the complex communication environment, a two-step cooperative guidance strategy is proposed to achieve the simultaneous attack under time-varying delays and switching topologies. In the first step, a distributed cooperative guidance law using neighboring information is designed to coordinate range-to-go and leading angle based on feedback linearization and consensus theory. The second step starts while multi missiles disconnect from each other and hit the target using PNG（Proportional Navigation Guidance）. Then, the algorithm with three steps is presented to select the parameters in the cooperative guidance law. And the stability of the multi-missile system is proven using Lyapunov-Krasovskii theory. Finally, a numerical simulation is given to demonstrate the effectiveness of the proposed cooperative guidance strategy.

关键词： Cooperative guidance Distributed strategy Consensus theory Time-varying delays Switching topologies

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3d-Printed Porous Peek Bone Implant with Enhanced Osseointegration– from mechanical Design to Clinical Applications

SSRN

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SSRN 2023年

作者： Liu, Yingjie Zhang, Jie Zheng, Jibao Kang, Jianfeng Dong, Enchun Liu, Shuguang Sun, Changning Li, Dichen Wang, Ling State Key Laboratory for Manufacturing System Engineering School of Mechanical Engineering Xi'an Jiaotong University Shaanxi Xi'An China Key Laboratory for Research and Evaluation of Additive Manufacturing Medical Devices Xi'an Jiaotong University ShaanXi Xi'An710054 China Academy of Orthopedics Guangdong Province Orthopaedic Hospital of Guangdong Province The Third Affiliated Hospital of Southern Medical University Guangzhou China Department of Oral and Maxillofacial Surgery Center of Stomatology Xiangya Hospital Central South University Hunan Changsha China School of Mechatronic Engineering and Automation Foshan University Foshan528225 China Institute of Orthopaedic & Musculoskeletal University College London Royal National Orthopaedic Hospital Stanmore United Kingdom

Although porous structure has become an inevitable trend in the development of PEEK (Poly-ether-ether-ketone) bone implants, there is a lack of research on its design and clinical application. Based on the specific clinical case of paranasal augmentation, this study designed a porous PEEK implant with mechanical stability and evaluated its clinical performance in osseointegration. Safety and mechanical stability criteria were established in the design of the porous PEEK implants. The FEM results showed that at a tightening load of 0.05 N·m, the PEEK implant with the pore size of 600 μm can achieve the balance between load-bearing ability and osseointegration as the safety factor of each implantation component beyond 2 times and the effective bone growth area of the interface bone reaching 95%. The PEEK implant was fabricated by fused filament fabrication (FFF) technology with cubic porous structure and applied clinically. The post-operative CT image of the patient proved new bone formation inside the implant with the bone volume fraction up to 41.8%, indicating the 3D-printed porous PEEK implants can achieve good osseointegration in situ. This study provides evidence of the feasibility and safety of 3D-printed porous PEEK implant, which will help promote its future application. © 2023, The Authors. All rights reserved.

关键词： Computerized tomography

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