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Attitude control without angular velocity measurement for flexible satellites

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Chinese Journal of Aeronautics 2018年第6期31卷 1345-1351页

作者： Qinghua ZHU Guangfu MA Xiaoting WANG Aiguo wu Department of Control Science and Control Engineering Harbin Institute of Technology Harbin 150001 China Shanghai Aerospace Control Technology Institute Shanghai 201109 China Harbin Institute of Technology Shenzhen Graduate School Shenzhen 518055 China Shanghai Key Laboratory of Aerospace Intelligent Control Technology Shanghai 201109 China

In this paper, by using quaternion models, the problem of attitude control is investigated for a class of flexible satellites. Two control laws are presented for the considered flexible satellite models to guarantee convergence of the closed-loop systems without using angular velocity measurement. One is in the form of a partial state feedback for the case where the modal variable is available, and the other is in the form of an observer-based partial state feedback for the case where the modal variable cannot be measured. Finally, an example is employed to illustrate the effectiveness of the proposed control laws.

关键词： Attitude control Flexible satellites Modal variables Quaternion models Passivity

A Simulation for the Piston Effect in Supercritical Carbon Dioxide with the Non-flow Model

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Journal of Thermal Science 2013年第5期22卷 472-477页

作者： Lingjiao Wei Dazhong Yuan Bangxian wu Dawei Tang Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

A simulation for piston effect in supercritical carbon dioxide by employing a simple model is conducted. In the first place, the thermal properties of carbon dioxide near its liquid-vapor critical point are discussed. It is calcu- lated that the heat capacity ratio and isobaric expansion coefficient of supercritical fluids are extremely high. Furthermore, the simulation for piston effect in supereritical carbon dioxide between two infinite vertical walls is presented. The numerical results prove that piston effect has a much faster speed of heat transfer than thermal conduction under mierogravity conditions. Moreover, the piston effect turns out to be stronger when closer to the critical point.

关键词： Piston effect Carbon dioxide Supercritical Thermal properties

Fault-tolerant finite-time dynamical consensus of double-integrator multi-agent systems with partial agents subject to synchronous self-sensing function failure

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Chinese Physics B 2022年第12期31卷 719-725页

作者： Zhi-Hai wu Lin-Bo Xie Engineering Research Center of Internet of Things Technology Applications of MOE School of Internet of Things EngineeringJiangnan UniversityWuxi 214122China

This paper investigates fault-tolerant finite-time dynamical consensus problems of double-integrator multi-agent systems(MASs)with partial agents subject to synchronous self-sensing function failure(SSFF).A strategy of recovering the connectivity of network topology among normal agents based on multi-hop communication and a fault-tolerant finitetime dynamical consensus protocol with time-varying gains are proposed to resist synchronous *** is proved that double-integrator MASs with partial agents subject to synchronous SSFF using the proposed strategy of network topology connectivity recovery and fault-tolerant finite-time dynamical consensus protocol with the proper time-varying gains can achieve finite-time dynamical *** simulations are given to illustrate the effectiveness of the theoretical results.

关键词： multi-agent systems synchronous self-sensing function failure finite-time dynamical consensus network topology connectivity recovery

Investigation of Endwall Flow Behavior with Plasma Flow Control on a Highly Loaded Compressor Cascade

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Journal of Thermal Science 2012年第4期21卷 295-301页

作者： Xiaohu ZHAO Yinghong LI Yun wu Jun LI Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University Xi' an 710038 China

To discover the flow behavior in the endwall region and mechanism of plasma flow control on a highly loaded compressor cascade, distributions of static pressure coefficient, total pressure loss coefficient and streamline pat- tern were investigated. Results show that cross flow from the pressure surface to neighboring suction surface ex- ists under pitch-wise pressure gradient. The deflected endwall boundary layer flow interacts with the incoming flow, and then both of them leave off the endwall in tile form of a span-wise vortex. Effect of angle of attack on static pressure is greater than that of free stream velocity. The distinct variations of total pressure loss with end- wall actuations are mainly located within the outer verge of a triangular area with high total pressure loss. Effect of pitch-vAse actuation on separated flows is much better than that of stream-wise actuation, and both enhance with the increase of angle of attack and actuation strength. An efficient method for plasma flow control in the endwall region is the increase of actuation strength, such as adjusting discharge voltage or changing plasma power supply.

关键词： plasma flow control compressor cascade endwall region vortex

Kernel broken smooth particle hydrodynamics method for crack propagation simulation applied in layered rock cells and tunnels

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Underground Space 2023年第3期10卷 55-75页

作者： Chengzhi Xia Zhenming Shi Hongchao Zheng Xiaohan wu School of Civil Engineering Tongji UniversityShanghai 200092China College of Environmental Science and Engineering Tongji UniversityShanghai 200092China

Understanding the cracking process of layered tunnels requires a high-fidelity *** smooth particle hydrodynamics(SPH),termed kernel broken SPH(KBSPH),was implemented to simulate the crack propagation and deformation of layered rock cells and field layered tunnels with dip angles of 0°–90°,and the results were compared with those of the laboratory *** attempts,including the bedding angle,interlayer distance,and lateral pressure coefficient,were made to investigate the crack propagation and deformation of layered ***,the pros and cons of the KBSPH method applied in the rock field were compared with those of other *** results indicate that the KBSPH can explicitly reproduce crack propagation by improving the kernel function with a totally damaged symbol,and the deformation responses have been captured *** infer that this method is effective and rapid in crack propagation and large deformation simulation for other types of rock tunnels.

关键词： Smooth particle hydrodynamics Kernel broken Layered rock tunnel Crack propagation

Quantifying coherence with dynamical discord

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Chinese Physics B 2021年第12期30卷 222-228页

作者： Lian-wu Yang Yun-Jie Xia School of Physical Science and Intelligent Engineering Jining UniversityQufu 273155China Shandong Provincial Key Laboratory of Laser Polarization and Information Technology Department of PhysicsQufu Normal UniversityQufu 273165China

Quantum coherence and discord are two kinds of manifestations of *** calculating the coherence and discord in the specific bipartite quantum systems,we show quantitative connections between the coherence and the discord in the bipartite quantum systems created from local systems with the help of incoherent *** show that the coherence bounds the dynamical discord,and under particular conditions of the initial quantum states,the coherence of single systems is equal to the dynamical *** extend these results to the multipartite quantum systems.

关键词： quantum coherence dynamical discord relative entropy

National trend of gastric cancer mortality in China(2003-2015):a population-based study

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Cancer Communications 2019年第1期39卷 228-232页

作者： Kun Gao Jun wu Key Laboratory of Biomedical Information Engineering of Ministry of Education School of Life Science and TechnologyXi’an Jiaotong UniversityXi’an 710049ShannxiP.R.China Department of Pharmaceutical and Administrative Sciences Presbyterian College School of Pharmacy307 North Broad StreetClintonSC 29325USA.

Background:Gastric cancer mortality decreased substantially over the last decades in most countries *** study aimed to assess the most recent national trend of gastric cancer mortality and examine the disparity of gastric cancer mortality between rural and urban areas in ***:The crude mortality data of gastric cancer by sex,age group,and area were obtained from China Health Statistical Yearbooks(2003-2015)covering 10%of Chinese *** age-standardized rates of mortality(ASRM)of gastric cancer in rural and urban areas were estimated using the 2010 Chinese Census population stratified by age,sex,and *** trend of mortality of gastric cancer was assessed by using Joinpoint ***:During the 13-year period,the ASRM was reduced from 31.5/100,000 in 2003 to 20.9/100,000 in 2015 in rural areas and from 18.9/100,000 in 2003 to 14.5/100,000 in 2015 in urban *** the male population,the annual percent changes of mortality were−2.2%in urban areas(95%confidence interval[CI]−3.8%to−0.6%;P<0.001)and−3.4%in rural areas(95%CI−5.1%to−1.8%;P<0.001).In the female population,the annual percent changes of mortality were−2.7%in urban areas(95%CI−4.2%to−1.2%;P<0.001)and−4.6%in rural areas(95%CI−5.5%to−3.7%;P<0.001).Conclusions:The declining trend of mortality of gastric cancer was presented from 2003 to 2015 in both rural and urban areas in *** decrease in gastric cancer mortality is greater in rural areas than in urban areas in China.

关键词： Gastric cancer Mortality Age-standardized rate Rural population Urban population Health service

Coupling dynamic analysis of spacecraft with multiple cylindrical tanks and flexible appendages

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Acta Mechanica Sinica 2016年第1期32卷 144-155页

作者： Wen-Jun wu Bao-Zeng Yue Hua Huang School of Aerospace Engineering Beijing Institute of Technology School of Automobile and Traffic Engineering Guangxi University of Science and Technology Satellite Communication Department China Academy of Space Technology

This paper is mainly concerned with the coupling dynamic analysis of a complex spacecraft consisting of one main rigid platform, multiple liquid-filled cylindrical tanks, and a number of flexible appendages. Firstly, the carrier potential function equations of liquid in the tanks are deduced according to the wall boundary conditions. Through employ- ing the Fourier-Bessel series expansion method, the dynamic boundaries conditions on a curved free-surface under a low-gravity environment are transformed to general simple differential equations and the rigid-liquid coupled sloshing dynamic state equations of liquid in tanks are obtained. The state vectors of rigid-liquid coupled equations are composed with the modal coordinates of the relative potential func- tion and the modal coordinates of wave height. Based on the B ernoulli-Euler beam theory and the D＇Alembert＇s prin- ciple, the rigid-flexible coupled dynamic state equations of flexible appendages are directly derived, and the coordi- nate transform matrixes of maneuvering flexible appendages are precisely computed as time-varying. Then, the cou- pling dynamics state equations of the overall system of the spacecraft are modularly built by means of the Lagrange＇s equations in terms of quasi-coordinates. Lastly, the cou-piing dynamic performances of a typical complex spacecraft are studied. The availability and reliability of the presented method are also confirmed.

关键词： Multiple liquid-filled cylindrical tanks TheFourier-Bessel series expansion method Low-gravityenvironment Maneuvering flexible appendages TheLagrange's equations in terms of quasi-coordinates

An energy constraint position-based dynamics with corrected SPH kernel

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Science China(Information Sciences) 2023年第1期66卷 144-157页

作者： Wei CAO Luan LYU Zhixin YANG Enhua wu College of Computer Science and Technology China University of Petroleum Faculty of Science and Technology University of Macau State Key Laboratory of Internet of Things for Smart City University of Macau State Key Laboratory of Computer Science Institute of Software Chinese Academy of Sciences Guangzhou Greater Bay Area Virtual Reality Research Institute

We introduce an improved position-based dynamics method with corrected smoothed particle hydrodynamics(SPH) kernel to simulate deformable solids. Using a strain energy constraint that follows the continuum mechanics, the method can maintain the efficiency and stability of the position-based approach while improving the physical plausibility of the simulation. We can easily simulate the behavior of anisotropic and plastic materials because the method is based on physics. Unlike the previous position-based simulations of continuous materials, we use weakly structured particles to discretize the model for the convenience of deformable object cutting. In this case, a corrected SPH kernel function is adopted to measure the deformation gradient and calculate the strain energy on each particle. We also propose a solution for the interparticle inversion and penetration in large deformation. To perform complex interaction scenarios, we provide a simple method for collision detection. We demonstrate the flexibility, efficiency, and robustness of the proposed method by simulating various scenes, including anisotropic elastic deformation, plastic deformation, model cutting, and large-scale elastic collision.

关键词： position-based dynamics deformable solids continuum mechanics