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Sliding-mode control for a two-dimensional piezo-positioning stage

IET control THEORY AND APPLICATIONS 2007年第4期1卷 1104-1113页

作者： Huang, Pa. Shieh, P.-H. Lin, F.-J. Shieh, H.-J. Natl Dong Hwa Univ Dept Elect Engn Hualien 974 Taiwan

A sliding-mode controller (SMC) for a two-dimensional piezo-positioning stage is proposed. A mathematical model representing the motion dynamics of the stage is developed in which a hysteresis friction force describing the hysteresis behaviour of one-dimensional motion is used and a non-contant stiffness with the cross-coupling dynamics due to the effect of bending of lever mechanism in the x and y axes is also included. Based on the dynamic model, the proposed SMC with an asymptotic sliding surface is designed. A stability anslysis is performed, and the transient performance is governed by the choice of control parameter values. With the proposed control scheme, the piezo-positioning stage is suitable for practical applications, especially in microscopy, with its need for validity of various trajectories. Experimental results show that the proposed controller provides high-performance dynamic characteristics and robustness to external load.

关键词： friction force Leverage external load controllers Slip forming Hysteresis Transient performance control parameter Slip surfaces

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Vibration control of rotationally periodic structures using passive piezoelectric shunt networks and active compensation

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JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 1999年第3期121卷 379-390页

作者： Tang, J Wang, KW Penn State Univ Dept Mech Engn Struct Dynam & Controls Lab University Pk PA 16802 USA

This paper proposes a multi-mode vibration suppression scheme for rotationally periodic structures. Identical active-passive hybrid piezoelectric networks are applied on each of the substructures, where active charge and current feedback is used together with passive piezoelectric shunts to optimize the network performance. By exploiting the rotational periodicity a new algorithm is synthesized to analytically determine the control parameters. It is shown that this hybrid approach can suppress all the spatial harmonics, which cannot be achieved by purely passive piezoelectric shunts. It is also observed that such a configuration requires much less control effort (voltage and power) when compared to a purely active approach.

关键词： compensated space harmonics Active Periodic structures Shunts (electrical) vibration control shunt Substructures Network current feedback control parameter

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Influence of boundaries on pattern selection in through-flow

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PHYSICA D-NONLINEAR PHENOMENA 1996年第1-3期97卷 253-263页

作者： Roth, D Buchel, P Lucke, M Muller, HW Kamps, M Schmitz, R UNIV SAARLAND INST THEORET PHYS D-66041 SAARBRUCKEN GERMANY FORSCHUNGSZENTRUM JULICH FORSCHUNGSZENTRUM HOCHSTLEISTUNGSRECHENZENTRUM D-52425 JULICH GERMANY FORSCHUNGSZENTRUM JULICH FORSCHUNGSZENTRUM INST FESTKORPERFORSCH D-52425 JULICH GERMANY

The problem of pattern selection in absolutely unstable open flow systems is investigated by considering the example of Rayleigh-Benard convection. The spatio-temporal structure of convection rolls propagating downstream in an externally imposed flow is determined for six different inlet/outlet boundary conditions. Results are obtained by numerical simulations of the Navier-Stokes equations and by comparison with the corresponding Ginzburg-Landau amplitude equation. A unique selection process is observed being a function of the control parameters and the boundary conditions but independent of history and system length. The problem can be formulated in terms of a nonlinear eigen/boundary value problem where the frequency of the propagating pattern is the eigenvalue.

关键词： Noise-sustained structure Ginzburg-landau equation Couette-taylor system Axial-flow Poiseuille flow Intermittency Convection Stability Absolute Axial flow Poiseuille flow convection ABSOLUTE intermittency Boundary conditions Process selection control parameter

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NUMERICAL MARFE STUDIES FOR A DEUTERIUM-CARBON PLASMA AT ASDEX UPGRADE

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PLASMA PHYSICS AND controlLED FUSION 1995年第7期37卷 723-739页

作者： KASTELEWICZ, H SCHNEIDER, R NEUHAUSER, J EURATOM Assoc. Max-Planck-Inst. fur Plasmaphys. Berlin Germany

Marfes-axisymmetric, poloidally localized plasma edge phenomena occurring in tokamaks close to the upper density limit-are studied numerically for a realistic ASDEX-upgrade single-null divertor geometry. An advanced version of the 2D tokamak edge multifluid code B2 is used, assuming plausible boundary conditions and radial transport laws. A deuterium plasma contaminated with carbon is chosen, since carbon is the most prominent impurity in tokamaks with graphite tiles and some form of oxygen gettering. All charge stares are treated as separate fluids. The formation of a made and its nonlinear behaviour is investigated in detail for realistic experimental scenarios. It is shown that a made may be readily stabilized by external feedback control using the radiated power as the control parameter. The whole set of stationary states can be represented in a diagram of steady states by a double-valued function, where the two branches describe made-free and made plasma states, respectively. The internal mechanism sustaining a state steady made, i.e. a localized region of enhanced density and lowered temperature relative to the surrounding medium, is discussed.

关键词： external feedback deuterium plasma digitally Steady state Countries (nations) Carbon EDGE PLASMAS transport law Boundary conditions Tokamak devices graphite tile control parameter

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Music in a bag? controlling the bag of Majorcan and Galician bagpipes

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017年第3期142卷 1454-1465页

作者： Ernoult, Augustin Fabre, Benoit Balosso-Bardin, Cassandre Franciosi, Ilya de la Cuadra, Patricio Univ Pierre & Marie Curie Univ Paris 06 Lutherie Acoust Mus Inst Jean le Rond Alembert Unite Mixte Rech UMR 7190CNRSSorbonne Univ F-7500 Paris France Univ Lincoln Chaire GeAcMus Sorbonne Univ Lincoln England Sorbonne Univ Chaire GeAcMus Paris France Pontificia Univ Catolica Chile Chaire GeAcMus Sorbonne Univ Santiago Chile

After defining the mechanical framework of the bag control of bagpipe, this paper presents a study of the bag pressure control in a musical context through the comparison of six players and two bagpipes: one Galician (gaita) and one Majorcan (xeremies), the latter mainly differentiated organologically by a much larger bag size. General observations first lead to the identification and interpretation of the range of control parameters observed. A more detailed analysis of the control parameters during the production of steady notes highlights the coordination between insufflations and the arm displacement necessary to produce a stable and continuous sound. Finally, the bag pressure variation is observed in a musical context and correlated with the musical task, thus, associating different control strategies to the different bagpipes played by the musicians. (C) 2017 Acoustical Society of America.

关键词： Insufflation control strategy Majorcan Music control parameter

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Learning in real-time search: A unifying framework

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JOURNAL OF ARTIFICIAL INTELLIGENCE RESEARCH 2006年第0期25卷 119-157页

作者： Bulitko, V Lee, G Univ Alberta Dept Comp Sci Edmonton AB T6G 2E8 Canada

Real-time search methods are suited for tasks in which the agent is interacting with an initially unknown environment in real time. In such simultaneous planning and learning problems, the agent has to select its actions in a limited amount of time, while sensing only a local part of the environment centered at the agent's current location. Real-time heuristic search agents select actions using a limited lookahead search and evaluating the frontier states with a heuristic function. Over repeated experiences, they refine heuristic values of states to avoid infinite loops and to converge to better solutions. The wide spread of such settings in autonomous software and hardware agents has led to an explosion of real-time search algorithms over the last two decades. Not only is a potential user confronted with a hodgepodge of algorithms, but he also faces the choice of control parameters they use. In this paper we address both problems. The first contribution is an introduction of a simple three-parameter framework (named LRTS) which extracts the core ideas behind many existing algorithms. We then prove that LRTA*, is an element of-LRTA*, SLA*, and gamma-Trap algorithms are special cases of our framework. Thus, they are unified and extended with additional features. Second, we prove completeness and convergence of any algorithm covered by the LRTS framework. Third, we prove several upper-bounds relating the control parameters and solution quality. Finally, we analyze the influence of the three control parameters empirically in the realistic scalable domains of real-time navigation on initially unknown maps from a commercial role-playing game as well as routing in ad hoc sensor networks.

关键词： Agents Converge Real time Frameworks algorithms Learning SEARCHING ALGORITHM control parameter

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Hydrological effects of climate variability and vegetation dynamics on annual fluvial water balance in global large river basins

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HYDROLOGY AND EARTH SYSTEM SCIENCES 2018年第7期22卷 4047-4060页

作者： Liu, Jianyu Zhang, Qiang Singh, Vijay P. Song, Changqing Zhang, Yongqiang Sun, Peng Gu, Xihui China Univ Geosci Lab Crit Zone Evolut Sch Earth Sci Wuhan 430074 Hubei Peoples R China Beijing Normal Univ Key Lab Environm Change & Nat Disaster Minist Educ Beijing 100875 Peoples R China Beijing Normal Univ State Key Lab Earth Surface Proc & Resource Ecol Beijing 100875 Peoples R China Beijing Normal Univ Acad Disaster Reduct & Emergency Management Fac Geog Sci Beijing 100875 Peoples R China Texas A&M Univ Dept Biol & Agr Engn College Stn TX USA Texas A&M Univ Zachry Dept Civil Engn College Stn TX USA CSIRO Land & Water GPO Box 1700 Canberra ACT 2601 Australia Anhui Normal Univ Coll Geog & Tourism Wuhu 241000 Anhui Peoples R China China Univ Geosci Sch Environm Studies Dept Atmospher Sci Wuhan 430074 Hubei Peoples R China

The partitioning of precipitation into runoff (R) and evapotranspiration (E), governed by the controlling parameter in the Budyko framework (i.e., n parameter in the Choudhury and Yang equation), is critical to assessing the water balance at global scale. It is widely acknowledged that the spatial variation in this controlling parameter is affected by landscape characteristics, but characterizing its temporal variation remains yet to be done. Considering effective precipitation (P-e), the Budyko framework was extended to the annual water balance analysis. To reflect the mismatch between water supply (precipitation, P) and energy (potential evapotranspiration, E-0), we proposed a climate seasonality and asynchrony index (SAI) in terms of both phase and amplitude mismatch between P and E-0. Considering streamflow changes in 26 large river basins as a case study, SAI was found to the key factor explaining 51 % of the annual variance of parameter n. Furthermore, the vegetation dynamics (M) remarkably impacted the temporal variation in n, explaining 67 % of the variance. With SAI and M, a semi-empirical formula for parameter n was developed at the annual scale to describe annual runoff (R) and evapotranspiration (E). The impacts of climate variability (P-e, E-0 and SAI) and M on R and E changes were then quantified. Results showed that R and E changes were controlled mainly by the P-e variations in most river basins over the globe, while SAI acted as the controlling factor modifying R and E changes in the East Asian subtropical monsoon zone. SAI, M and E-0 have larger impacts on E than on R, whereas P-e has larger impacts on R.

关键词： ROENTGEN watersheds hydrologic alteration vegetation dynamics MOMENT MAGNITUDE River basins control parameter temporal variations

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Transitions between drift waves in a magnetized cylindrical plasma: experiments and fluid model, solved with a spectral method

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EUROPEAN PHYSICAL JOURNAL D 2013年第1期67卷 7-1-7-8页

作者： Gravier, Etienne Plaut, Emmanuel Caron, Xavier Jenny, Mathieu Univ Lorraine CNRS UMR 7198 Inst Jean Lamour F-54506 Vandoeuvre Les Nancy France Univ Lorraine CNRS UMR 7563 LEMTA F-54516 Vandoeuvre Les Nancy France

A bifurcation scenario between collisional drift waves with different azimuthal wavenumbers m in a magnetized plasma column is experimentally studied, and compared with a linear two-fluid model solved with a new spectral method. The control parameter is the potential of an internal metallic tube in the experiments, the electron drift along the axis of the cylinder in the model. By increasing this parameter, we find bifurcations from azimuthal modes m = 5 to m = 1. The linear properties of the model agree well with the experimental observations.

关键词： BIFURCATION spectral methods cylindrical plasmas DRIFT WAVES Metal tubing Drift control parameter

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Terahertz generation and chaotic dynamics in GaN NDR diode

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SEMICONDUCTOR SCIENCE AND TECHNOLOGY 2004年第3期19卷 451-456页

作者： Lü, JT Cao, JC Chinese Acad Sci Inst Microsyst & Informat Technol State Key Lab Funct Mat Informat Shanghai 200050 Peoples R China

Inflection of carriers in the Gamma valley, prior to the usual intervalley scattering when the electric field is approximately less than 300 kV cm(-1), can cause a negative differential velocity in zinc-blende (Zb) GaN. GaN n(+)nn(+) oscillators based on this mechanism have a self-oscillating frequency in the terahertz (THz) range. The situation is completely different from the case of traditional Gunn-effect devices. We have carefully studied the electric domain dynamics and the self-oscillation frequency dependence on the applied do field. When the diode is driven by a do and an ac bias, a typical nonlinear dynamic system is constructed with the do bias, the ac amplitude and the ac frequency as the control parameters. Different mode locking and chaotic modes show up when tuning the control parameters.

关键词： diodes Electric fields control parameter direct current AC Bias gallium nitrate Inflection DC bias THZ RANGE Mode locking terahertz Frequency dependence Nonlinear dynamic systems AC frequency

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The quantum computational speed of a single Cooper-pair box

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PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES 2011年第10期43卷 1792-1797页

作者： Obada, A. -S. F. Abo-Kahla, D. A. M. Metwally, N. Abdel-Aty, M. Univ Bahrain Fac Sci Dept Math Isa Town Bahrain Al Azhar Univ Fac Sci Dept Math Cairo Egypt Ain Shams Univ Fac Educ Dept Math Cairo Egypt Sohag Univ Fac Sci Dept Math Sohag Egypt

The speed of computations is investigated by means of the orthogonality speed for a charged qubit interacting with a single cavity field prepared initially in a Fock state or Binomial state. We observe that the rate of the computational speed is related to the number of photons inside the cavity. Moreover, we show that the qubit-field coupling plays an opposite role, where the speed of computations is decreased as the coupling is increased. We suggest using the number of photons in the field as a control parameter to improve the speed of computations. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Photon Binomial SINGLE-CAVITY speed control parameter

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