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Real-time Feed-forward Force Compensation for Active Magnetic Bearings System Based on H∞ Controller

Chinese Journal of Mechanical Engineering 2011年第1期24卷 58-66页

作者： gao Hui XU Longxiang College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

There are two kinds of unbalance vibrations—force vibration and displacement vibration due to the existence of unbalance excitation in active magnetic bearings（AMB） system. And two unbalance compensation methods—closed-loop feedback and open loop feed-forward are presented to reduce the force vibration. The transfer function order of the control system directly influencing the system stability will be increased when the closed-loop method is adopted, which makes the real-time compensation not easily achieved. While the open loop method would not increase the primary transfer function order, it provides conditions for real-time compensation. But the real-time compensation signals are not easy to be obtained in the open loop method. To implement real-time force compensation, a new method is proposed to reduce the force vibration caused by the rotor unbalance on the basis of AMB active control. The method realizes real-time and on-line force auto-compensation based on H∞ controller and one novel feed-forward compensation controller, which makes the rotor rotate around its inertia axis. The time-variable feed-forward compensatory signal is provided by a modified adaptive variable step-size least mean square（VSLMS） algorithm. And the relevant least mean square（LMS） algorithm parameters are used to solve the H∞ controller weighting functions. The simulation of the new method to compensate some frequency-variable and sinusoidal signals is completed by MATLAB programming, and real-time compensation is implemented in the actual AMB experimental system. The simulation and experiment results show that the compensation scheme can improve the robust stability and the anti-interference ability of the whole AMB system by using H∞ controller to achieve close-loop control, and then real-time force unbalance compensation is implemented. The proposed research provides a new control strategy containing real-time algorithm and H∞ controller for the force compensation of AMB system. And

关键词： active magnetic bearings H∞ robust controller sensitivity and complementary sensitivity VSLMS algorithm feed-forward compensation

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Quantum-inspired bacterial foraging algorithm for parameter adjustment in green cognitive radio

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Journal of Systems Engineering and Electronics 2015年第5期26卷 897-907页

作者： Hongyuan gao Chenwan Li School of Information and Communication Engineering Harbin Engineering University

Parameter adjustment that maximizes the energy efficiency of cognitive radio networks is studied in this paper where it can be investigated as a complex discrete optimization problem. Then a quantum-inspired bacterial foraging algorithm(QBFA)is proposed. Quantum computing has perfect characteristics so as to avoid local convergence and speed up the optimization of QBFA. A proof of convergence is also given for this *** superiority of QBFA is verified by simulations on three test functions. A novel parameter adjustment method based on QBFA is proposed for resource allocation of green cognitive radio. The proposed method can provide a globally optimal solution for parameter adjustment in green cognitive radio networks. Simulation results show the proposed method can reduce energy consumption effectively while satisfying different quality of service(Qo S)requirements.

关键词： green cognitive radio parameter adjustment quantum computing bacterial foraging algorithm

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Experimental Research on Salt-out Particle Motion and Concentration Distribution in a Vortex Pump Volute

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Chinese Journal of Mechanical Engineering 2010年第1期23卷 53-59页

作者： gao Bo YANG Minguan School of Energy and Power Engineering Jiangsu University Zhenjiang 212013 China

The vortex pump is suitable for salt solution transportation. But the salt-out flow mechanism in the pump has not been understood fully. Salt-out layer formation and growth rate are closely related to crystal particle motion and concentration distribution. Study on the particle hydrodynamic characteristics in the pump volute becomes a key problem, because the crystal particles are mainly distributing in this zone after they enter the pump. Phase Doppler particle analyzer（PDPA） is used to measure the two-phase flow field in a model pump volute to get more understanding about the salt-out phenomenon. The crystal particle velocities are obtained in all three peripheral, radial and axial directions. Particle size and particle number density（PND） measurements are also performed in the experiment. Results are presented and discussed along the radial direction under different pump operating conditions, as well as various axial measurement positions. It is found that particle velocity gradient of peripheral component varies with the pump discharge. There is a turning point of relation between peripheral velocity component and discharge. Radial flow velocity curves look like a saddle shape and velocity magnitudes are changing greatly with the discharge. The non-equilibrium velocity feature between liquid and solid phase on this direction is also remarkable. Particles flow into the impeller at radial position R〈I, and the axial velocity component increases in this region. The particle size curve shows an open-up parabola distribution. The largest particles are distributing near the casing peripheral wall. As flow rate increases, accordingly PND increases. It also grows up in the axial-outward direction towards the suction cover. Crystal particle aggregation phenomenon can be revealed from the analysis of particle size and PND distribution, and the aggregation region is determined as well. Research results are helpful for optimal design of this kind of pump preventing salt-out

关键词： vortex pump salt-oat particle motion concentration distribution

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Microstructure and mechanical behavior of laser aided additive manufactured low carbon interstitial Fe_(49.5)Mn_(30)Co_(10)Cr_(10)C_(0.5)multicomponent alloy

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Journal of Materials Science & Technology 2021年第18期77卷 38-46页

作者： Y.Chew z.G.zhu F.Weng S.B.gao F.L.Ng B.Y Lee G.J.Bi Singapore Institute of Manufacturing Technology 73 Nanyang Drive637662Singapore School of Mechanical Aerospace Engineering Nanyang Technological University50 N any ang Avenue639798Singapore

Laser aided additive manufacturing(LAAM)was used to fabricate bulk Fe_(49.5)Mn_(30)Co_(10)Cr_(10)C_(0.5)interstitial multicomponent alloy using pre-alloyed *** room temperature yield strength(σ_y),ultimate tensile strength(σ_(UTS))and elongation(ε_(UTS))were 645 MPa,917 MPa and 27.0%*** asbuilt sample consisted of equiaxed and dendritic cellular structures formed by elemental *** cellular structures together with oxide particle inclusions were deemed to strengthen the *** other contributing components include dislocation strengthening,friction stress and grain boundary *** highε_(UTS)was attributed to dislocation motion and activation of both twinning and transformation-induced plasticity(TWIP and TRIP).Tensile tests performed at-40℃and-130℃demonstrated superior tensile strength of 1041 MPa and 1267 MPa ***,almost no twinning was observed in the fractured sample tested at-40℃and-130℃.Instead,higher fraction of strain-induced hexagonal close-packed(HCP)εphase transformation of 21.2%were observed for fractured sample tested at-40℃,compared with 6.3%in fractured room temperature sample.

关键词： Multicomponent alloys Laser aided additive manufacturing Additive manufacturing Microstructure Mechanical property

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Brown, Jeremy. City versus Countryside in Mao＇s China： Negotiating the Divide Cambridge： Cambridge University Press, 2012. ISBN 9781107424548 xiv＋254pp. $29.99 （paperback）. DOI 10.3868/s020-004-015-0007-5

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Frontiers of History in China 2015年第1期10卷 168-171页

作者： James z. gao University of Maryland

This volume is a significant addition to the literature on PRC history. It discusses China＇s urban-rural dichotomy, one of the most pressing social problems in contemporary China. The author has done extensive interviews to explore how ＂people in the Tianjin region of north China negotiated the rural-urban gap in their everyday lives＂（p. 3）. Most urban historians argue that since the 14th century, China has transformed itself from an empire of villages to an empire of cities. After 1860, China saw an urgent need to deal with the increasing threat of domestic rebellions and foreign intrusions by learning Western industrial technology.

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Complex Behaviors of a Simple Traffic Model

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Communications in Theoretical Physics 2006年第5X期46卷 952-960页

作者： gao Xing-Ru Department of Physics and Institute of Theoretical Physics Beijing Normal University Beijing 100875 China Fundamental Teaching Department Beijing Union University Beijing 100101 China

In this paper, we propose a modified traffic model in which a single car moves through a sequence of traffic lights controlled by a step function instead of a sine function. In contrast to the previous work [Phys. Rev. E 70 （2004） 016107], we have investigated in detail the dependence of the behavior on four parameters, ω,α,η and α1, and given three kinds of bifurcation diagrams, which show three kinds of complex behaviors. We have found that in this model there are chaotic and complex periodic motions, as well as special singularities. We have also analyzed the characteristic of the complex period motion and the essential feature of the singularity.

关键词： traffic model complex behavior chaos bifurcation diagram singularity

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Efficacy of Bunao Fuyuan decoction on cerebral ischemia and reperfusion injury in vitro

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Journal of Traditional Chinese Medicine 2020年第5期40卷 758-765页

作者： gao Lei Gu Weichao Department of Rehabilitation Medicine Huai'an Traditional Chinese Medicine Hospital Affiliated to Nanjing University of Chinese MedicineHuaian 223001China Department of Traditional Chinese Medicine The Affiliated Huai'an Hospital of Xuzhou Medical University and The Second People's Hospital of Huai'anHuaian 223002China

OBJECTIVE:To investigate the protective efficacy of Bunao Fuyuan decoction(BNFY)on cerebral Ischemia/reperfusion(I/R)***:The mouse PC12 cells were chosen,and the oxidative-glucose deprivation/re-oxygenation(OGD/R)injury model were established to simulate cerebral I/R *** was selected as a positive drug,and a gradient dose of BNFY was given for 6,12 and 24 h.3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide(MTT)assay were used to detect cell viability at each time *** apoptosis was measured by terminal deoxynucleotidyl transferase-mediated d UTP-botin nick end labeling(TUNEL)*** linked immunosorbent assay was used to detect the expression of tumor necrosis factor(TNF)-α,interleukin(IL)-6,IL-1βand platelet activating factor(PAF).Western blot assay were performed to detect the expression of key regulators[toll-like receptor 4(TLR4),nuclear factor kappa-B(NF-κB),p-p38 mito-gen-activated protein kinase(MAPK)and p-Akt(also known as protein kinase B,PKB)]of cell survival and inflammatory ***:The results of MTT assay and TUNEL staining assay revealed that BNFY significantly increased cell viability and inhibited cell apoptosis of PC12 cells following OGD/R,***,the expression of TNF-α,1 L-6,1 L-1βand PAF were decreased after BNFY *** the results of Western blot assay showed that BNFY downregulated TLR4,NF-κB,p-p38 MAPK expression and upregulated p-Akt ***:Our findings suggest that BNFY may play a role in protecting OGD/R injured PC12 cells through inhibiting the inflammatory response and cell apoptosis.

关键词： Inflammatory response Ischemic stroke PC12 Oxidative-glucose deprivation/re-oxygenation Bunao Fuyuan decoction

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Phase separation in cGAS-STING signaling

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Frontiers of Medicine 2023年第5期17卷 855-866页

作者： Quanjin Li Pu gao CAS Key Laboratory of Infection and Immunity National Laboratory of BiomacromoleculesCAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of SciencesBeijing100101China University of Chinese Academy of Sciences Beijing100049China

Biomolecular condensates formed by phase separation are widespread and play critical roles in many physiological and pathological ***-STING signaling functions to detect aberrant DNA signals to initiate anti-infection defense and antitumor *** the same time,cGAS-STING signaling must be carefully regulated to maintain immune ***,exciting recent studies have reported that biomolecular phase separation exists and plays important roles in different steps of cGAS-STING signaling,including cGAS condensates,STING condensates,and IRF3 *** addition,several intracellular and extracellular factors have been proposed to modulate the condensates in cGAS-STING *** studies reveal novel activation and regulation mechanisms of cGAS-STING signaling and provide new opportunities for drug ***,we summarize recent advances in the phase separation of cGAS-STING signaling and the development of potential drugs targeting these innate immune condensates.

关键词： biomolecular condensates phase separation cGAS-STING pathway cGAS STING cGAMP interferon

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Dropout Rademacher complexity of deep neural networks

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Science China(Information Sciences) 2016年第7期59卷 173-184页

作者： Wei gao zhi-Hua zHOU National Key Laboratory for Novel Software Technology Nanjing University Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing University

Great successes of deep neural networks have been witnessed in various real applications. Many algorithmic and implementation techniques have been developed; however, theoretical understanding of many aspects of deep neural networks is far from clear. A particular interesting issue is the usefulness of dropout,which was motivated from the intuition of preventing complex co-adaptation of feature detectors. In this paper,we study the Rademacher complexity of different types of dropouts, and our theoretical results disclose that for shallow neural networks(with one or none hidden layer) dropout is able to reduce the Rademacher complexity in polynomial, whereas for deep neural networks it can amazingly lead to an exponential reduction.

关键词： artificial intelligence machine learning deep learning dropout Rademacher complexity

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A NOTE ON EXACT CONVERGENCE RATE IN THE LOCAL LIMIT THEOREM FOR A LATTICE BRANCHING RANDOM WALK

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Acta Mathematica Scientia 2018年第4期38卷 1259-1268页

作者： zhiqiang gao Laboratory of Mathematics and Complex Systems（Ministry of Education of China） School of Mathematical SciencesBeijing Normal UniversityBeijing 100875China

Consider a branching random walk, where the underlying branching mechanism is governed by a Galton-Watson process and the moving law of particles by a discrete random variable on the integer lattice z. Denote by zn（z） the number of particles in the n-th generation in the model for each z ∈ z. We derive the exact convergence rate in the local limit theorem for zn（z） assuming a condition like ＂EN（logN）1＋λ 〈 ∞＂ for the offspring distribution and a finite moment condition on the motion law. This complements the known results for the strongly non-lattice branching random walk on the real line and for the simple symmetric branching random walk on the integer lattice.

关键词： lattice branching random walks local limit theorem exact convergence rate

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