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Numerical Investigation into the Transient Behavior of the Spike-Type Rotating Stall for a Transonic Compressor Rotor

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Fluid Dynamics & Materials Processing 2022年第3期18卷 761-773页

作者： Pengfei Ju Fangfei Ning Zhiting Tong Jingying Wang 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 Research Institute of Aero-Engine Beihang UniversityBeijing100191China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics School of Energy and Power EngineeringBeihang UniversityBeijing100191China School of Energy and Power Engineering Shandong UniversityJinan250061China Shandong Engineering Laboratory for High-Efficiency Energy Conservation and Energy Storage Technology&Equipment Shandong UniversityJinan250061China

In this paper,a numerical investigation into a spike-type rotating stall process is carried out considering a transonic compressor rotor(the NASA Rotor 37).Through solution of the Unsteady Reynolds-Averaged Navier-Stokes(URANS)equations,the evolution process from an initially circumferentially-symmetric near-stall flow field to a stable stall condition is simulated without adding any artificial *** the near-stall operating point,periodic fluctuations are present in the overall flow of the ***,the blockage region in the channel periodically shifts from middle span to the *** fluctuating condition does not directly lead to stall,while the full-annulus calculation eventually evolves to ***,a kind of“early disturbance”feature appears in the dynamic signals,which propagates forward ahead of the rotor.

关键词： Transonic compressor spike stall numerical simulation early disturbance dynamic signal

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Cover Picture: Materials and Corrosion. 11/2024

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Materials and Corrosion 2024年第11期75卷 1399-1399页

作者： Wei Zhang Mingyang Zhou Huifang Yue Danmin Peng Xi Qiu Jijun Yang Key Laboratory of Radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and Technology Sichuan University Chengdu China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

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Collaborative Fall Detection and Response using Wi-Fi Sensing and Mobile Companion Robot

arXiv

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arXiv 2024年

作者： Chen, Yunwang Kang, Yaozhong Zhao, Ziqi Hong, Yue Meng, Lingxiao Meng, Max Q.-H. The Shenzhen Key Laboratory of Robotics Perception and Intelligence Southern University of Science and Technology Shenzhen518055 China The Department of Electrical and Electronic Engineering SUSTech Shenzhen China The School of System Design and Intelligent Manufacturing SUSTech Shenzhen China

This paper presents a collaborative fall detection and response system integrating Wi-Fi sensing with robotic assistance. The proposed system leverages channel state information (CSI) disruptions caused by movements to detect falls in non-line-of-sight (NLOS) scenarios, offering non-intrusive monitoring. Besides, a companion robot is utilized to provide assistance capabilities to navigate and respond to incidents autonomously, improving efficiency in providing assistance in various environments. The experimental results demonstrate the effectiveness of the proposed system in detecting falls and responding effectively. Copyright © 2024, The Authors. All rights reserved.

关键词： Fall detection

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Effect of an initial boundary layer thickness on the turbulent flow over a backward-facing step

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JMST Advances 2021年第4期3卷 55-62页

作者： Kim, Jungwoo Department of Mechanical System Design Engineering Seoul National University of Science and Technology Seoul Korea

The effect of an initial boundary layer thickness on the turbulent flow over a backward-facing step is investigated by using large eddy simulations. Three different initial boundary layer thickness, $$\delta /h$$ = 0.26, 0.5, 1.2 and three different Reynolds numbers, $${\text{Re}} =$$ 5,100, 24,000 and 45,000 are considered. Expansion ratio is 1.2. The characteristics of the turbulent flow over a backward-facing step (e.g. reattachment length, maximum pressure coefficient, mean streamwise velocity, rms streamwise velocity fluctuations) significantly depends on both the Reynolds number ( $${\text{Re}}$$ ) and the initial boundary layer thickness ( $$\delta /h$$ ) rather than $${\text{Re}}_{\theta }$$ or $$\delta /h$$ alone as considered in the literature. In addition at high $${\text{Re}}_{\theta }$$ the effect of initial boundary layer thickness shows an asymptotic characteristic in terms of $${\text{Re}}_{\theta }$$ to some extent. On the other hand, the instability of the detached shear layer based on the momentum thickness ( $$St_{\theta }$$ ) could be reasonably scale

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Observation of gap solitons on a CMOS chip

Observation of gap solitons on a CMOS chip

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2023 Optica Nonlinear Optics Topical Meeting, NLO 2023

作者： Choi, Ju Won Sohn, Byoung-Uk Sahin, Ezgi Chen, George F.R. Xing, Peng Ng, Doris K.T. Eggleton, Benjamin J. Tan, Dawn T.H. Photonics Devices and System Group Singapore University of Technology and Design 8 Somapah Rd Singapore487372 Singapore Institute of Microelectronics A*STAR 2 Fusionopolis Way #08-02 Innovis Tower Singapore138634 Singapore Institute of Photonics and Optical Science School of Physics The University of Sydney SydneyNSW2006 Australia The University of Sydney SydneyNSW2006 Australia

ISBN: (纸本)9781957171234

We demonstrate gap solitons in an on-chip USRN Bragg grating. We experimentally observe a slow light effect where the group velocity is reduced to 35 % – 40 % of the speed of light in vacuum, variation in the temporal delay of 7 ps at low peak powers of 15.7 W–36.6 W, accompanied by 2.7× temporal compression of input pulses. Optica Nonlinear Optics Topical Meeting 2023 © Optica Publishing Group 2023 © 2023 The Author(s)

关键词： Slow light

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Efficient calculation of fluid-induced wall shear stress within tissue engineering scaffolds by an empirical model

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Medicine in Novel technology and Devices 2023年第2期18卷 267-271页

作者： Husham Ahmed Matthew Bedding-Tyrrell Davide Deganello Zhidao Xia Yi Xiong Feihu Zhao Zienkiewicz Centre for Computational Engineering and Department of Biomedical Engineering Faculty of Science&EngineeringSwansea UniversitySwanseaSA18ENUK Welsh Centre for Printing and Coating Faculty of Science and EngineeringSwansea UniversitySwanseaSA18ENUK Centre for Nanohealth Swansea University Medical School and Faculty of MedicineHealth and Life ScienceSwansea UniversitySwanseaSA35AUUK School of System Design and Intelligent Manufacturing Southern University of Science and TechnologyShenzhen518055China

Mechanical stimulation,such as fluid-induced wall shear stress(WSS),is known that can influence the cellular ***,in some tissue engineering experiments in vitro,mechanical stimulation is applied via bioreactors to the cells in cell culturing to study cell physiology and *** 3D cell culturing,porous scaffolds are used for housing the *** is known that the scaffold porous geometries can influence the scaffold permeability and internal WSS in a bioreactor(such as perfusion bioreactor).To calculate the WSS generated on cells within scaffolds,usually computational fluid dynamics(CFD)simulation is ***,the limitations of the computational method for WSS calculation are:(i)the high time cost of the CFD simulation(in particular for the highly irregular geometries);(ii)accessibility to the CFD model for some cell culturing experimentalists due to the knowledge *** address these limitations,this study aims to develop an empirical model for calculating the WSS based on scaffold *** model can allow the tissue engineers to efficiently calculate the WSS generated within the scaffold and/or determine the bioreactor loading without performing the computational simulations.

关键词： Wall shear stress Permeability Empirical model Tissue engineering scaffold Bioreactor

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Spatio-Temporal Action Order Representation for Mobile Manipulation Planning

Spatio-Temporal Action Order Representation for Mobile Manip...

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IEEE International Workshop on Robot and Human Communication (ROMAN)

作者： Yosuke Kawasaki Masaki Takahashi Graduate School of Science and Technology Keio University Yokohama Japan Department of System Design Engineering Keio University Yokohama Japan

ISBN: (数字)9781728188591

ISBN: (纸本)9781665406802

Social robots are used to perform mobile manipulation tasks, such as tidying up and carrying, based on instructions provided by humans. A mobile manipulation planner, which is used to exploit the robot’s functions, requires a better understanding of the feasible actions in real space based on the robot’s subsystem configuration and the object placement in the environment. This study aims to realize a mobile manipulation planner considering the world state, which consists of the robot state (subsystem configuration and their state) required to exploit the robot’s functions. In this paper, this study proposes a novel environmental representation called a world state-dependent action graph (WDAG). The WDAG represents the spatial and temporal order of feasible actions based on the world state by adopting the knowledge representation with scene graphs and a recursive multilayered graph structure. The study also proposes a mobile manipulation planning method using the WDAG. The planner enables the derivation of many effective action sequences to accomplish the given tasks based on an exhaustive understanding of the spatial and temporal connections of actions. The effectiveness of the proposed method is evaluated through practical machine experiments performed. The experimental result demonstrates that the proposed method facilitates the effective utilization of the robot’s functions.

关键词： Uncertainty Social robots Knowledge representation Planning Task analysis Robots

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Fast Decentralized Multi-Agent Collision Avoidance Based on Safe-Reachable Sets

Fast Decentralized Multi-Agent Collision Avoidance Based on ...

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IEEE Conference on Decision and Control

作者： Zikai Ouyang Junwei Liu Haibo Lu Wei Zhang Shenzhen Key Laboratory of Control Theory and Intelligent Systems School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China Peng Cheng Laboratory Shenzhen China

This paper presents a decentralized multi-agent collision avoidance method for systems with single integrator dynamics and identical maximum speeds. The key to our approach lies in the concept of safe-reachable sets, which define the set of positions that each agent can reach while avoiding collisions with its neighbors for any admissible controllers. With this concept, we develop a distributed controller by solving an online convex program, which is shown to guarantee collision-free trajectories. Furthermore, under a no temporary deadlock condition, we establish that each agent converges to its target position. Our approach is also efficient in terms of makespan, representing the total time needed for convergence. Simulation results demonstrate the effectiveness of our approach in terms of safety, convergence, and efficiency.

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Creep Behavior of a Novel Ods Ferrite Steel Reinforced with Ultra-Fine Y2(Zr0.6, Ti0.4)2O7 Particles

SSRN

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SSRN 2024年

作者： Zhao, Zhenyu Cao, Yuankui Zhang, Yuyang Fu, Ao Zhang, Ruiqian Zhong, Yuntao Li, Jia Fang, Qihong Liu, Bin State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of China Chengdu610041 China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body China

Oxide dispersion strengthened (ODS) ferrite steel is a competitive candidate structural material for the Generation IV fission reactors. In this work, a novel ODS ferrite steel reinforced with ultra-fine Y2(Zr0.6, Ti0.4)2O7 particles was prepared by powder metallurgy method, which exhibit superior mechanical properties at elevated temperatures. Creep tested of the ODS ferrite steel at 800 ℃ was conducted to reveal its high-temperature creep failure mechanism. This ODS steel has an average grain size of 1.31 μm, and the mean size and number density of the ultra-fine oxide particles are 5.48 nm and 4.85×1023 m-3, respectively. When the apply creep stress is 100 MPa, the creep rupture time of the ODS steel is 2448.5 h, and the minimum creep rate is only 1.05×10-7 s-1. Under the similar creep stress at 800 ℃, the creep rate of this ODS steel is at least one order of magnitude lower than that of other typical ODS steels reported in the literatures, showing excellent creep properties. By fitting the data of minimum creep rate, apply stress and effective stress normalized by shear modulus, the creep threshold stress of the ODS steel was determined as 56.2 MPa, and the true stress exponent was calculated as 4.5 ± 1.0, which indicates that the creep mechanism is dominated by dislocation. Orowan bypass mechanism and dislocation climb over the particle mechanism play a major role in this dislocation mediated creep behavior. Due to the strong hindering effect of dislocation motion caused by the ultra-fine and dispersed Y2(Zr0.6, Ti0.4)2O7 particles, the novel ODS ferrite steel thereby achieved excellent creep properties. © 2024, The Authors. All rights reserved.

关键词： Creep

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Prediction of boiling crisis in a full-size rod bundle with spacer grids 14

Prediction of boiling crisis in a full-size rod bundle with ...

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14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water reactor Fuel Performance Conference, TOP FUEL 2019

作者： Li, Quan Li, Yuanming Avramova, M. Huang, Yongzhong Liu, Zhenhai Ma, Chao Qi, Feipeng Zhao, Bo Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Nuclear Engineering North Carolina State University NC27695 United States

In this paper, two-phase CFD approach is used to simulate the boiling crisis in PSBT rod bundle with spacer grids. The 5×5 rod bundle contains 17 spacer grids, which are finely modeled through UG code. Eulerian two-fluid model coupled with the extended wall boiling model is used to simulate the subcooled boiling flow. The used sub-models for nucleation site density and bubble departure diameter both take the effects of high pressure into consideration. The calculated surface averaged void fraction in the central four sub-channels shows good agreement with the experimental data at high void fraction conditions, while higher than the measured data at low void fraction conditions. Based on the two-phase simulations, the void fraction distribution in the plane section on which thermocouples are placed is used as the criteria for CHF prediction. The numerical simulation of boiling two-phase flow and prediction method of CHF provide new approach for the optimization of spacer grid and fuel assembly. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water reactor Fuel Performance *** rights reserved.

关键词： Forecasting

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