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Effects of Wall Emissivity on Aerodynamic Heating in Scramjets

Fluid Dynamics & Materials Processing 2020年第6期16卷 206-216页

作者： Yue Zhou Pengfei Ju School of Aeronautical Science and Technology Beihang UniversityBeijing100191China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education(Tianjin University of Technology) Tianjin300384China

The effects of the wall emissivity on aerodynamic heating in a scramjet are *** supersonic turbulent combustion flow including radiation is solved in the framework of a decoupled strategy where the flow field is determined first and the radiation field *** particular,a finite difference method is used for solving the flow while a DOM(iscrete ordinates method)approach combined with a WSGGM(weighted sum of gray gases)model is implemented for radiative *** nonreactive turbulent channel flows are examined for a DLR hydrogen fueled scramjet changing parametrically the wall *** results indicate that the wall radiative heating rises greatly with increasing the wall *** the wall emissivity rises,the radiative source and total absorption increase,while the incident radiation decreases ***,although the radiative heating can reach a significant level,its contribution to the total aerodynamic heating is relatively limited.

关键词： Scramjet aerodynamic heating wall emissivity radiation

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Hamiltonian Dynamics and Targeted Energy Transfer of a Grounded Bistable Nonlinear Energy Sink

SSRN

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SSRN 2022年

作者： Li, Shuangbao Zhou, Xinxing Chen, Jianen Research Institute of Science and Technology Civil Aviation University of China Tianjin300300 China College of Science Civil Aviation University of China Tianjin300300 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

A two-degree-of-freedom nonlinear mechanical system describing a damped linear oscillator weakly coupled to a lightweight grounded bistable nonlinear energy sink is proposed to investigate the targeted energy transfer (TET) under asymmetric local nonlinear potentials. The Bogdanov-Takens bifurcations of equilibria are discussed to reflect the bistable and asymmetric characteristics of the system. Through projections of isoenergetic manifolds, the topological features of the Hamiltonian dynamics under $1:1$ internal resonance have been investigated, which induces conditions for energy localization and exchange. In the general case, the topological features of the Hamiltonian dynamics related to the nonlinear normal modes (NNMs) are classified by the Poincare map, the relations between the NNMs and the Hamiltonian dynamics have been interpreted through the frequency energy plots. The results show that introducing the asymmetric characteristics may enhance the TET and realize the complete TET. © 2022, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

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Data-driven modeling fast-slow coupling delayed dynamics using noisy data and sparse enhancement

Data-driven modeling fast-slow coupling delayed dynamics usi...

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International Conference on Industrial Artificial Intelligence (IAI)

作者： Huifang Tang Yuqiang Wu Yingming Dong Cheng Cheng Xiuting Li College of Science Huazhong Agricultural University Wuhan China School of Artificial Intelligence and Automation Huazhong University of Science and Techonology Wuhan China Yunnan Key Laboratory of Mechatronics Applied Technology Yunnan Mechanical Research and Design Institute of Machinery Research Institute Group Yunnan China Autonomous Intelligent Unmanned System Engineering Research Center Ministry of Education of China Huazhong University of Science and Technology Wuhan China

In this work, we focus on fast-slow delayed dynamical systems, which are usually described by coupled delayed differential equations with two-time scales. The purpose of this article is to propose a data-driven discovery method to identify the fast-slow delayed differential equations from noisy measurements. The proposed method blends delay dictionary-based sparse identification of nonlinear dynamics (SINDy) framework and a fixed interval sampling strategy. Specifically, we leverage the SINDy methodology to describe the fast-slow delayed differential equations by a few active terms of a large dictionary containing the delay terms and many candidate nonlinear basis functions. To identify the active terms and the corresponding coefficients, a sequential thresholded re-weighted ℓ 2 least squares algorithm is used to solve the resulting sparse regression problem to enhance the sparsity. Once a sparse model with fixed delay is selected, the proposed method further estimates the delayed time by calculating the reconstruction error from the sparse model until the one that makes the reconstruction error minimum. We verify the effectiveness of the proposed method with several classical fast-slow coupling delayed systems. The experimental results show that the proposed method can well automate the fast-slow delayed differential equations from noisy data and the delayed terms also can be detected accurately.

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Wearable Bending Wireless Sensing with Autonomous Wakeup by Piezoelectric and Triboelectric Hybrid Generator

SSRN

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SSRN 2023年

作者： Wang, Lu Fei, Zhenxuan Wu, Zutang Ye, Yao Qi, Youchao Wang, Jiuhong Zhao, Libo Zhang, Chi Zhang, Yun Qin, Guangzhao Jiang, Zhuangde Maeda, Ryutaro Research Institute for Intelligent Sensing Technology and System Xi’an710049 China CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro-nano Energy and Sensor Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of Sciences Beijing101400 China School of Mechanical Engineering Xi’an Jiaotong University Xi’an710049 China Shandong Laboratory of Yantai Advanced Materials and Green Manufacturing Yantai265503 China Northwest Institute of Nuclear Technology Xi’an710024 China Research Institute for Micronano Sensing Technology Yantai264006 China Hangzhou Dianzi University

The Internet of Things calls for the demand for wearable self-powered sensors for human motion monitoring and interaction. However, the redundant data and large amount of power consumption limits the application in sustainable wireless sensing. In this study, a flexible hybrid generator with bridge structure design for self-powered wearable sensor is proposed. When harvesting energy from the finger bent motion, it combines contact separation mode for triboelectric nanogenerator (TENG) with bending d31 mode for piezoelectric generator (PEG). To highlight the significance, we propose an autonomous wake-up wireless sensing method by hybrid generator in wearable bending. Different from recording and transmitting data all the time, the TENG signal as a trigger to record the PEG voltage amplitude as angle sensing data for wireless transmitting. Concise and accurate sensing data with autonomous wake-up is expected to reduce the computational burden and power consumption for wireless sensing and provide more possibilities for wearable wireless monitoring and human-computer interaction. The wireless manipulator interaction experiment based on this hybrid generator as wearable bending sensor verifies the feasibility of this scheme, which has a great application prospect in wearable self-powered sensors field such as virtual reality and robot control. © 2023, The Authors. All rights reserved.

关键词： Electric power utilization

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Generative API usage code recommendation with parameter concretization

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Science China(Information Sciences) 2019年第9期62卷 51-72页

作者： Chi CHEN Xin PENG Jun SUN Zhenchang XING Xin WANG Yifan ZHAO Hairui ZHANG Wenyun ZHAO School of Computer Science Fudan University Shanghai Key Laboratory of Data Science Fudan University Shanghai Institute of Intelligent Electronics & Systems Pillar of Information System Technology and Design Singapore University of Technology and Design Research School of Computer Science Australian National University

Many programming languages and development frameworks have extensive libraries(e.g., JDK and Android libraries) that ease the task of software engineering if used effectively. With numerous library classes and sometimes intricate API(application programming interface) usage constraints, programmers often have difficulty remembering the library APIs and/or using them correctly. This study addresses this problem by developing an engine called DeepAPIRec, which automatically recommends the API usage *** to the existing proposals, our approach distinguishes itself in two ways. First, it is based on a tree-based long short-term memory(LSTM) neural network inspired by recent developments in the machinelearning community. A tree-based LSTM neural network allows us to model and reason about variable-length,preceding and succeeding code contexts, and to make precise predictions. Second, we apply data-flow analysis to generate concrete parameters for the API usage code, which not only allows us to generate complete code recommendations but also improves the accuracy of the learning results according to the tree-based LSTM neural network. Our approach has been implemented for supporting Java programs. Our experimental studies on the JDK library show that at statement-level recommendations, DeepAPIRec can achieve a top-1 accuracy of about 37% and a top-5 accuracy of about 64%, which are significantly better than the existing approaches. Our user study further confirms that DeepAPIRec can help developers to complete a segment of code faster and more accurately as compared to IntelliJ IDEA.

关键词： code recommendation API deep learning data dependency parameter concretization

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Rigid-flexible and Fluid-structure Coupling Dynamics of Folding Plate

Rigid-flexible and Fluid-structure Coupling Dynamics of Fold...

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第八届国际振动工程会议

作者： Sanya Chen Wenhua Hu Yalu Zhao Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of Technology National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology

The variable configuration of the folding wings is beneficial to take into account the maneuverability and endurance of the aircraft. During the flight, the elastic deformation and folding motion of the folding wing will induce additional aerodynamic forces, which will produce new deformation and new aerodynamic forces on the wing structure, and this reciprocal coupling will make the folding wing response may tend to diverge and lead to structural damage. In this paper,the principle of geometric similarity is used to simplify the folding wing into a folding plate and study its rigid-flexible aerodynamic coupling dynamics, which has certain practical significance as well as the theoretical value.

关键词： Rigid-flexible and Fluid-structure Coupling Dynamics of Folding Plate

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Study on Scanning Forming Methods of Machining Work-Piece Surface

Research Square

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Research Square 2021年

作者： Wang, Xueteng Niu, Xinghua Yu, Zizhao Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System National Demonstration Center for Experimental Mechanical and Electrical Engineering China School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

In the process of machine tool cutting, there are strict geometric relations among the cutting edge curve / tool surface, machine tool movement and workpiece surface, and the machine tool movement is also related to the type of tool. Firstly, the forming methods of cutting workpiece surface are analyzed and summarized from the geometric point of view, and the scanning forming method and its geometric expression are studied, and the research technical route of forming turning scanning forming is put forward. Then, the mathematical modeling and Simulation of forming turning are carried out according to the proposed technical route. Finally, taking the groove of the inner ring of the formed turning ball bearing as an example, the mathematical modeling of the design surface of the workpiece and the machined surface of the workpiece is carried out. The radial dimension changes of the workpiece caused by the cutting force and tool wear are analyzed, and the simulation of the machined surface of the workpiece is carried out. © 2021, CC BY.

关键词： Scanning

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Multi-Objective Optimal Feedback Controls for Under-Actuated Dynamical system

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Journal of Shanghai Jiaotong university(Science) 2020年第5期25卷 545-552页

作者： QIN Zhichang XIN Ying SUN Jianqiao School of Transportation and Vehicle Engineering Shandong University of TechnologyZibo 255000ShandongChina School of Mechanical Engineering Tianjin University of TechnologyTianjin 300384China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of TechnologyTianjin 300384China School of Engineering University of California MercedCA 95343USA

This paper presents a study of optimal control design for a single-inverted pendulum(SIP)system with the multi-objective particle swarm optimization(MOPSO)*** proportional derivative(PD)control algorithm is utilized to control the *** the SIP system is nonlinear and the output(the pendulum angle)cannot be directly controlled(it is under-actuated),the PD control gains are not tuned with classical *** this work,the MOPSO method is used to obtain the best PD *** use of multi-objective optimization algorithm allows the control design of the system without the need of linearization,which is not provided by using classical *** multi-objective optimal control design of the nonlinear system involves four design parameters(PD gains)and six objective functions(time-domain performance indices).The HausdorfF distances of consecutive Pareto sets,obtained in the MOPSO iterations,are computed to check the convergence of the MOPSO *** MOPSO algorithm finds the Pareto set and the Pareto front *** simulations and experiments of the rotary inverted pendulum system are done to verify this design *** and experimental results show that the multi-objective optimal controls offer a wide range of choices including the ones that have comparable performances to the linear quadratic regulator(LQR)control.

关键词： multi-objective optimal control under-actuated system particle swarm optimization(PSO) rotary inverted pendulum

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Adaptive Robust Control of an Uncertain Robotic Manipulator with Guaranteed Transient and Steady State Performance

Adaptive Robust Control of an Uncertain Robotic Manipulator ...

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International Conference on Advanced Robotics and Mechatronics (ICARM)

作者： Yifan Liu Dejie Yu Zilu Wang Zheshuo Zhang Hui Yin State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha P. R. China Intelligent Transportation System Research Center School of information and electrical engineering Zhejiang Uni-versity City College Hangzhou Zhejiang P. R. China School of Mechanical and Automotive Engineering South China University of Technology Guangzhou Guangdong P. R. China

Guaranteeing human-specified performance in robot control subject to complex uncertainties is challenging. This study takes time-varying (possibly fast), bounded with unknown bounds uncertainties into consideration in controlling an uncertain robotic manipulator system (URMS). We employ an adaptive law to on-line estimate the unknown bounds for uncertainty compensation, and prescribed transient and steady state performance (TSSP) are guaranteed by using a state transformation technique. As a result, a class of adaptive robust control with prescribed TSSP is proposed. Simulation results are provided to validate the effectiveness of the proposed approach.

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Curriculum reform of "fundamentals of mechanical design" for non-mechanical majors based on OBE engineering education concept 3

Curriculum reform of "fundamentals of mechanical design" for...

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3rd International Conference on Education Technology Management, ICETM 2020

作者： Liu, Jingna Hao, Pujun Lyu, Linwei Ma, Wenpeng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China

ISBN: (纸本)9781450388757

Focusing on the non-mechanical students' weak mechanical knowledge, a new cultivation mode founded on the outcome-oriented education (OBE) is suggested to improve the teaching effect for "Fundamentals of mechanical design". The teaching course contents are optimized to make students' learning process proceed simultaneously with project case study. The teaching methods of innovative project driven and problem-oriented are adopted. Students can be guide to change the passive learning mode by autonomous learning mode with the online learning resources. The innovative methods can be recommended to the process of curriculum design to reform the content. The course experiment has been changed into online and offline mixed teaching, so as to improve students' experimental practice time and cultivate their ability of integrating theory with practice, analyzing problems and solving problems. Finally, the formative evaluation mode with the learning results as the assessment index is adopted to improve the students' comprehensive ability. Compared with the control class, the experimental class has greatly improved the excellent rate and pass rate. In the questionnaire survey, the experimental class students have a higher recognition for the curriculum reform. © 2020 ACM.

关键词： Students

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