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Controller
Kinds of Controller Terms modified by Controller Selected AbstractsA DESIGN CONCEPT OF AUTONOMOUS CONTROLLER FOR IMPROVING SEISMIC PROOF CAPABILITY OF SEMI-ACTIVE CONTROL DEVICEEXPERIMENTAL TECHNIQUES, Issue 4 2010M.-H. Shih First page of article [source] ABSOLUTE STABILITY AND APPLICATION TO DESIGN OF OBSERVER-BASED CONTROLLER FOR NONLINEAR TIME-DELAY SYSTEMSASIAN JOURNAL OF CONTROL, Issue 3 2007Bassem Ben Hamed ABSTRACT In this paper we present a new sufficient condition for absolute stability of delay Lure system. This condition improves the one given in [1]. We use this new criterion to construct an observer-based control for a class of nonlinear time-delay systems. Some examples are given to illustrate the results of this paper. [source] A DUAL-MODE ADAPTIVE ROBUST CONTROLLER APPLIED TO THE SPEED CONTROL OF A THREE-PHASE INDUCTION MOTORASIAN JOURNAL OF CONTROL, Issue 2 2005Caio D. Cunha ABSTRACT This work presents a Dual-Mode Adaptive Robust Controller applied to the angular shaft speed control of a three-phase induction motor. A liaison between a Model Reference Adaptive Controller (MRAC) and a Variable Structure Model Reference Adaptive Controller (VS-MRAC) through a tuning parameter is obtained using fuzzy logic. The basic idea of the Dual-Mode controller is adding both the advantages of the VS-MRAC transient behavior with the steady-state properties of the conventional MRAC. [source] COMMENTS ON «TUNING RULES FOR THE PID CONTROLLER USING A DMC STRATEGY»ASIAN JOURNAL OF CONTROL, Issue 4 2004Jing-Chung Shen ABSTRACT It is pointed out that the tuning rules for under damped system and non-minimum phase system that given by Haeri is incorrect. [source] A GLOBAL EXPONENTIAL OUTPUT-FEEDBACK CONTROLLER FOR INDUCTION MOTORSASIAN JOURNAL OF CONTROL, Issue 4 2000M. Feemster ABSTRACT In this paper, we design an output-feedback, rotor position/rotor flux controller for the full-order, nonlinear dynamic model of an induction motor. The singularity free controller does not require measurement of rotor flux or rotor velocity and yields global exponential rotor position and rotor flux tracking. The proposed controller is termed output-feedback due to the inexpensive/simplistic manner in which stator current measurements can be obtained (e.g., the most primitive method of measuring current can be achieved through simple voltage measurements across known resistive elements). Experimental results are included to verify the effectiveness of the proposed controller. [source] A PASSIVITY PLUS FLATNESS CONTROLLER FOR THE PERMANENT MAGNET STEPPER MOTORASIAN JOURNAL OF CONTROL, Issue 1 2000Hebertt Sira-Ramírez ABSTRACT A passivity based controller, in suitable combination with the flatness property of the system, is proposed for the effective feedback equilibrium to equilibrium regulation, via planned trajectory tracking, of the angular position in a permanent magnet (PM) stepper motor. The control scheme is shown to be easily modifiable as to include traditional proportional-integral-derivative (PID) feedback control actions which efficiently account for unmodeled load torque perturbations. [source] Dynamic performance analysis of novel unified power flow controller with computer simulation and scaled-model experimentEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2008Byung M. Han Abstract This paper describes dynamic performance analysis of Unified Power Flow Controller (UPFC) composed of cascaded H-bridge and single-phase multi-winding transformers for isolation. The operational characteristic was analyzed through simulations with PSCAD/EMTDC, and experimental works with a scaled model. The UPFC proposed in this paper can be directly connected to the transmission line without series injection transformers. It has flexibility to expand the operation voltage by increasing the number of H-bridges. Copyright © 2007 John Wiley & Sons, Ltd. [source] Automatic generation control of multi-area power system using fuzzy logic controllerEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2008P. Subbaraj Abstract This paper presents an application of Fuzzy Logic Controller (FLC) with triangular and gauss membership functions to study Automatic Generation Control (AGC) of a four-area interconnected power system. Out of the four areas three have steam turbines and one has hydro turbine. All steam turbines in the system contain the reheat effect of non-linearity and hydro turbine contains upper and lower constraints for generation rate. The result proves that the performance of FLC with Gaussian membership function is better than that of conventional controller. Copyright © 2007 John Wiley & Sons, Ltd. [source] Spatial sampling requirements for monitoring upper-air climate change with radiosondesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2008Mark P. McCarthy Abstract The global climate observing system upper air network (GUAN) was established to provide a network of high quality radiosonde stations with sufficient historical data records, and a commitment to future observing, in support of the needs of the climate research community. An assessment of the spatial sampling requirements for such a network in order to monitor large-scale climate changes has been conducted. The GUAN provides adequate coverage for monitoring global, tropical and hemispheric mean climate. Priority stations within the GUAN have been identified based upon their unique contribution to the network. Further sampling improvements to the GUAN may be possible by utilizing radiosonde stations located in India, Africa and northern polar regions. To keep sampling-related trend error below 0.05 K/decade in the troposphere, and 0.1 K/decade in the stratosphere, requires a radiosonde station to be located approximately every 30° longitude and 15° latitude north of 30°N. The inhomogeneous distribution of radiosonde stations in the tropics and southern hemisphere place a stronger requirement of 20° longitude and 10° latitude south of 30°N. The radiosonde network is inadequate for monitoring humidity except in the northern mid-latitudes. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] A novel approach to assessing percutaneous VX poisoning in the conscious guinea-pig,JOURNAL OF APPLIED TOXICOLOGY, Issue 5 2008Helen Mumford Abstract Nerve agents like VX (S-2-diisopropylaminoethyl-O-ethyl-methylphosphonothiolate) are potent irreversible acetylcholinesterase (AChE) inhibitors. Following percutaneous nerve agent exposure there is a slower rate of absorption, later onset and longer duration of signs of poisoning. Relatively little is known about the physiological effects of percutaneously applied nerve agent in unanaesthetised laboratory animals. Heart rate (ECG), brain electrical activity (EEG), body temperature, locomotor activity and clinical signs were monitored following percutaneous application of VX to conscious guinea-pigs. A fall in heart rate (bradycardia) preceded incapacitation following the highest VX dose, and occurred in the absence of incapacitation at the lower doses. Following the highest dose of VX (0.592 mg kg,1) three out of four animals died within 24 h. The lower two doses of VX (0.296 and 0.148 mg kg,1), produced extended periods of bradycardia in the absence of observable signs of poisoning. Bradycardia preceded, or occurred in the absence of, a temperature decrease; seizure-like EEG changes were not observed at any of the VX doses tested. Acetylcholinesterase activity was significantly inhibited in the blood and most brain areas at 48 h. There were significant dose-related decreases in body weight at 24 and 48 h following VX. This preliminary study suggests that decreased heart rate may be an early sign of the toxic effects of VX, whereas temperature and observable clinical signs are not good early indicators of percutaneous VX poisoning in this animal model. Future studies will use this model to assess the benefit of administering medical countermeasures in response to a defined decrease in heart rate. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. This article was published online on 5 December 2007. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected [30 May 2008]. [source] An Adaptive Controller for Two Cooperating Flexible ManipulatorsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1 2003Christopher J. Damaren The control problem for two serial flexible multilink robots which carry a common rigid payload is considered. An adaptive controller with feedback and feedforward elements is presented which can track a prescribed trajectory for the payload with simultaneous vibration suppression when the manipulated payload is sufficiently large. A free load-sharing parameter appears in the passivity-based control law which allows the torque requirement to be shared between the two arms in a largely arbitrary fashion. Simulation results using a complex model are given which demonstrate excellent tracking performance in the face of complete payload uncertainty. © 2003 Wiley Periodicals, Inc. [source] Long lead time flood warnings: reality or fantasy?METEOROLOGICAL APPLICATIONS, Issue 1 2009B. W. Golding Abstract This paper reviews recent advances in weather forecasting capability in the United Kingdom and their implications for increasing the lead time with which flood warnings can be issued. The events of summer 2007 have highlighted the vulnerability of parts of the United Kingdom to flooding and the need for long lead time flood warnings to enable the protection of people and critical infrastructure. Historically, computer weather forecasting models have been unable to forecast at the scales of importance for flood warning, and so the warning processes have been forced to rely on measurements on the ground. Examples are presented to demonstrate that new forecasting technologies, currently being implemented, enable warnings to be produced much earlier, provided they are couched in probabilistic terms and interpreted appropriately. Crown Copyright © 2009. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] The Application of the Sliding Mode Controller on the Ship Roll Reduction in Random Waves Using Genetic AlgorithmNAVAL ENGINEERS JOURNAL, Issue 4 2006Ming-Chung Fang The paper presents the sliding mode controller technique with roll reduction function on the ship rudder to simulate ship motion in random sea. By way of the rudder operation, the trackkeeping ability of the sliding mode controller on the ship is also examined using the line-of-sight (LOS) guidance technique. To reduce computer time consumption, the optimized design parameters of sliding mode controller tuned by genetic algorithm are obtained from ship motion simulation in regular waves. Based on the present simulation results in random waves, the combined heading/roll sliding mode controller including LOS technique developed here works for either roll reduction or track-keeping while the ship is maneuvering in waves. [source] Comparison of the capabilities of accelerated solvent extraction and sonication as extraction techniques for the quantification of kavalactones in piper methysticum (Kava) roots by high performance liquid chromatography with ultra violet detectionPHYTOCHEMICAL ANALYSIS, Issue 2 2007Emma Warburton Abstract A conventional extraction technique of sonication has been compared, in terms of extraction efficiency, extraction time and amount of solvent, with the more novel technique of accelerated solvent extraction for the extraction of kavain from the powdered roots of Piper methysticum (Kava) with acetone. The extracts were analysed using high-performance liquid chromatography with ultra violet detection. The effects of varying solvent volume and extraction time upon the quantity of kavain extracted with sonication, and the effects of varying temperature upon the kavain extraction efficiency by ASE, were investigated. ASE was found to be more efficient with respect to time and solvent volume required; however, a good agreement was found between the kavain concentration obtained using both extraction techniques. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] Enhanced Performance Assessment of Subspace Model-Based Predictive Controller with Parameters TuningTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2007Qiang Zhang Abstract This study focuses on performance assessment of model predictive control. An MPC-achievable benchmark for the unconstrained case is proposed based on closed-loop subspace identification. Two performance measures can be constructed to evaluate the potential benefit to update the new identified model. Potential benefit by tuning the parameter can be found from trade-off curves. Effect of constraints imposed on process variables can be evaluated by the installed controller benchmark. The MPC-achievable benchmark for the constrained case can be estimated via closed-loop simulation provided that constraints are known. Simulation of an industrial example was done using the proposed method. Cette étude porte sur l'évaluation de la performance du contrôle prédictif par modèles (MPC). On propose un banc d'essai adapté au MPC pour le cas non contraint en se basant sur l'identification de sous-espaces en boucle fermée. Deux mesures de performance sont élaborées pour évaluer l'avantage potentiel de mettre à jour le nouveau modèle identifié. L'avantage potentiel par réglage du paramètre peut s'obtenir à partir des courbes de compromis. L'effet des contraintes imposé sur les variables de procédé peut être évalué par le banc d'essai de contrôleur installé. Le banc d'essai adapté au MPC pour le cas contraint peut être estimé par la simulation en boucle fermée dans la mesure où les contraintes sont connues. On a réalisé la simulation d'un exemple industriel à l'aide de la méthode proposée. [source] Assimilation of IASI at the Met Office and assessment of its impact through observing system experimentsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 639 2009F. Hilton Abstract Observations from the Infrared Atmospheric Sounding Interferometer (IASI), onboard EUMETSAT's MetOp satellite, have been assimilated at the Met Office in global and regional numerical weather-prediction systems since 27 November 2007. Pre-operational trials of IASI assimilation in the global model during the summer of 2007 delivered a positive impact on forecasts approximately twice as large as that shown by the Atmospheric InfraRed Sounder (AIRS) on the EOS-Aqua satellite. A series of observing system experiments confirmed the relative performance of IASI and AIRS, and showed that impact from IASI is equivalent to a single Advanced Microwave Sounding Unit-A (AMSU-A) combined with a single Microwave Humidity Sounder (MHS). The results of an IASI assimilation trial for the winter of 2007 were consistent with those of the summer trial, although the impact was slightly lower overall. The assessment of impact is strongly dependent on the variables and methods chosen for verification: assimilation trials with the regional model showed similar improvements to the large-scale fields (e.g. mean-sea-level pressure and geopotential height) as seen in the global model, but no forecast impact was seen for variables such as visibility and rain-rate. © Crown Copyright 2009. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] Unsteady exact solutions of the flow equations for three-dimensional spherical atmospheresTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 635 2008A. Staniforth Abstract Time-dependent, closed-form solutions of the 3D Euler equations describing motion relative to a uniformly rotating coordinate frame are derived. The spherical geopotential approximation is applied but not the shallow-atmosphere and hydrostatic approximations. The solutions correspond to cyclostrophically and hydrostatically balanced vortices that are steady in inertial space and whose symmetry axes do not coincide with the rotation axis of the coordinate frame. The inertial-frame flow velocities are readily transformed to a precisely spherical rotating coordinate system in which the 3D Euler equations contain centrifugal as well as Coriolis terms. In this form the solutions may be used to test numerical models formulated in spherical coordinates under the spherical geopotential approximation, so long as the centrifugal terms are explicitly included as forcing terms. The development is repeated for the hydrostatic and non-hydrostatic primitive equations (with the shallow-atmosphere approximation) and for the shallow-water equations. In the latter case, the required explicit centrifugal force may be provided by a zonally symmetric addition to the free surface height, with an identically equal orographic elevation to ensure conservation of mass. The solutions are then identical to the unsteady shallow-water solutions of Läuter et al. that inspired this study. ©Crown Copyright 2008. Reproduced with the permission of the Controller of HMSO and the Queen's Printer for Scotland. Published by John Wiley & Sons, Ltd. [source] Stability of some exact solutions of the shallow-water equations for testing numerical models in spherical geometryTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 632 2008A. Staniforth Abstract Five families of exact axisymmetric solutions of the nonlinear shallow-water equations in spherical geometry have recently been proposed as an aid to the development and testing of global numerical models. Sufficient conditions for the stability of these solutions are here derived to guide the choice of values for the family parameters. Thus it can be ensured that any significant time evolution occurring in a numerical model initialised with one of these exact solutions is of numerical origin, and does not reflect an inherent physical instability. With the caveat that only sufficient conditions for stability are examined, it appears that planetary rotation stabilises the solutions (as would be so if the flow were governed by barotropic vorticity dynamics), and that low Rossby and Froude numbers favour their stability. © Crown Copyright 2008. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] A linear-stability analysis of the semi-implicit semi-Lagrangian discretization of the fully-compressible equationsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 632 2008T. J. Payne Abstract We give a linear-stability analysis of the two-time-level semi-implicit discretization of the adiabatic fully-compressible equations on an f -plane. Previous work has shown that the scheme is stable with respect to perturbations to a hydrostatic and isothermal basic state if the same time-implicit weight is used throughout and is greater than ½. In this note, we generalize this result to the case where different time weights are used for different terms. © Crown Copyright 2008. Reproduced with the permission of the Controller of HMSO and the Queen's Printer for Scotland. Published by John Wiley & Sons, Ltd. [source] A monotonically-damping second-order-accurate unconditionally-stable numerical scheme for diffusionTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 627 2007Nigel Wood Abstract We present a new two-step temporal discretization of the diffusion equation, which is formally second-order-accurate and unconditionally stable. A novel aspect of the scheme is that it is monotonically damping: the damping rate is a monotonically-increasing function of the diffusion coefficient, independent of the size of the time step, when the diffusion coefficient is independent of the variable being diffused. Furthermore, the damping rate increases without bound as the diffusion coefficient similarly increases. We discuss the nonlinear behaviour of the scheme when the diffusion coefficient is a function of the diffused variable. The scheme is designed to maintain any steady-state solution. We present examples of the performance of the scheme. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] In situ and remote-sensing measurements of the mean microphysical and optical properties of industrial pollution aerosol during ADRIEXTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue S1 2007S. R. Osborne Abstract We present a summary of the principal physical and optical properties of aerosol particles using the FAAM BAE-146 instrumented aircraft during ADRIEX between 27 August and 6 September 2004, augmented by sunphotometer, lidar and satellite retrievals. Observations of anthropogenic aerosol, principally from industrial sources, were concentrated over the northern Adriatic Sea and over the Po Valley close to the aerosol sources. An additional flight was also carried out over the Black Sea to compare east and west European pollution. Measurements show the single-scattering albedo of dry aerosol particles to vary considerably between 0.89 and 0.97 at a wavelength of 0.55 µm, with a campaign mean within the polluted lower free troposphere of 0.92. Although aerosol concentrations varied significantly from day to day and during individual days, the shape of the aerosol size distribution was relatively consistent through the experiment, with no detectable change observed over land and over sea. There is evidence to suggest that the pollution aerosol within the marine boundary layer was younger than that in the elevated layer. Trends in the aerosol volume distribution show consistency with multiple-site AERONET radiometric observations. The aerosol optical depths derived from aircraft measurements show a consistent bias to lower values than both the AERONET and lidar ground-based radiometric observations, differences which can be explained by local variations in the aerosol column loading and by some aircraft instrumental artefacts. Retrievals of the aerosol optical depth and fine-mode (<0.5 µm radius) fraction contribution to the optical depth using MODIS data from the Terra and Aqua satellites show a reasonable level of agreement with the AERONET and aircraft measurements. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] Modelling suppressed and active convection.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 626 2007Comparing a numerical weather prediction, cloud-resolving, single-column model Abstract This paper describes the design of and basic results from a case study to compare simulations of convection over the Tropical West Pacific. Simulations are carried out using a cloud-resolving model (CRM), a global numerical weather prediction (NWP) model and a single-column version of the NWP model (SCM). The experimental design for each model type is discussed and then results are compared. The periods simulated each include a regime with strong convective activity, a much more suppressed regime with far less convection, as well as the transition between these regimes. The description of the design and basic results from this study are given in some detail, as a study including all these model types is relatively new. Comparing the local forcing due to the dynamics in the NWP model with the observed forcing used to drive the CRM and SCM it is found that there is good agreement for one period chosen but significant differences for another. This is also seen in fields such as rain rate and top-of-atmosphere radiation. Using the period with good agreement we are able to identify examples of biases in the NWP model that are also reproduced in the SCM. Also discussed are examples of biases in the NWP simulation that are not reproduced in the SCM. It is suggested that understanding which biases in the SCM are consistent with the full NWP model can help focus the use of an SCM in this framework. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] Semi-geostrophic solutions for flow over a ridgeTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 623 2007M. J. P. Cullen Abstract An algorithm for solving the semi-geostrophic (SG) equations using real physical variables in terrain-following coordinates is developed and used to demonstrate the expected rate of convergence of solutions of the complete equations of motion to SG solutions as the Rossby number is reduced. The tests are carried out with significant orography in a vertical slice geometry. Two asymptotic limits are tested. The SG limit is singular in one of the limits and smooth in the other. The results show the validity of using the SG model for diagnostic purposes in appropriate regimes. They also expose a number of boundary condition and numerical issues, showing that comparison with rigorous error estimates is a useful way of validating numerical procedures. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] Boundary layer mechanisms in extratropical cyclonesTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 623 2007Robert J. Beare Abstract This paper revisits the mechanism for the interaction of the boundary layer with extratropical cyclones. Two diagnostic approaches are compared: Ekman pumping and potential vorticity. Ekman pumping derives from the boundary layer stress which induces convergence and ascent. boundary layer potential vorticity contains in a single quantity both the vorticity and stratification. These quantities are compared for an idealized extratropical cyclone life cycle simulated with the Met Office Unified Model. A significant component of the boundary layer stress and thus Ekman pumping at occlusion is forced by the cold conveyor-belt jet in the unstable boundary layer. In contrast, much of the boundary layer depth-averaged potential vorticity is contained within the stable warm-sector region. Inversion of the warm-sector PV indicates a small local deepening of about 2.5 hPa. Moreover, switching off the boundary layer mixing in the unstable cold sector has much more impact than in the stable warm sector. The sensitivity of the cyclone and its boundary layer to basic-state jet strength is then investigated. The maximum friction velocity scales closely with the initial maximum jet strength. This demonstrates the important role of the large-scale flow in organizing the boundary layer structure. Changes in the minimum pressure produced by altering the boundary layer parametrization correspond closely to changes in the surface stress averaged over the cyclone. Different operational changes to the boundary layer scheme produce small and compensating changes to the cyclone minimum pressure over three days. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd [source] Design of a Symmetry Controller for Cycling Induced by Electrical Stimulation: Preliminary Results on Post-Acute Stroke PatientsARTIFICIAL ORGANS, Issue 8 2010Emilia Ambrosini Abstract This study deals with the design of a controller for cycling induced by functional electrical stimulation. The controller will be exploitable in the rehabilitation of hemiparetic patients who need to recover motor symmetry. It uses the pulse width as the control variable in the stimulation of the two legs in order to nullify the unbalance between the torques produced at the two crank arms. It was validated by means of isokinetic trials performed both by healthy subjects and stroke patients. The results showed that the controller was able to reach, and then maintain, a symmetrical pedaling. In the future, the controller will be validated on a larger number of stroke patients. [source] A DUAL-MODE ADAPTIVE ROBUST CONTROLLER APPLIED TO THE SPEED CONTROL OF A THREE-PHASE INDUCTION MOTORASIAN JOURNAL OF CONTROL, Issue 2 2005Caio D. Cunha ABSTRACT This work presents a Dual-Mode Adaptive Robust Controller applied to the angular shaft speed control of a three-phase induction motor. A liaison between a Model Reference Adaptive Controller (MRAC) and a Variable Structure Model Reference Adaptive Controller (VS-MRAC) through a tuning parameter is obtained using fuzzy logic. The basic idea of the Dual-Mode controller is adding both the advantages of the VS-MRAC transient behavior with the steady-state properties of the conventional MRAC. [source] Recursive Back-Stepping Design of An Adaptive Fuzzy Controller for Strict Output Feedback Nonlinear SystemsASIAN JOURNAL OF CONTROL, Issue 3 2002Wei-Yen Wang ABSTRACT In this paper, a back-stepping adaptive fuzzy controller is proposed for strict output feedback nonlinear systems. The unknown nonlinearity and external disturbances of such systems are considered. We assume that only the output of the system is available for measurement. As a result, two filters are constructed to estimate the states of strict output feedback systems. Since fuzzy systems can uniformly approximate nonlinear continuous functions to arbitrary accuracy, the adaptive fuzzy control theory combined with a tuning function scheme is developed to derive the control laws of strict output feedback systems that possess unknown functions. Moreover, the H, performance condition is introduced to attenuate the effect of the modeling error and external disturbances. Finally, an example is simulated in order to confirm the applicability of the proposed method. [source] Anthropogenic warming of central England temperatureATMOSPHERIC SCIENCE LETTERS, Issue 4 2006David J. Karoly Abstract The variability of central England temperature (CET) at inter annual, decadal and 50-year time scales, as simulated by the HadCM3 model, agrees well with its observed variability over the period 1700,1900. The observed warming in annual-mean CET of about 1.0 °C since 1950 is very unlikely to be due to natural climate variations and is consistent with the response to anthropogenic (ANT) forcing, demonstrating a significant human influence on this warming. © Crown Copyright 2006. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] Analysis of a regularized, time-staggered discretization applied to a vertical slice model,ATMOSPHERIC SCIENCE LETTERS, Issue 4 2006Mark Dubal Abstract A regularized and time-staggered discretization of the two-dimensional, vertical slice Euler equation set is described and analysed. A linear normal mode analysis of the time-discrete system indicates that unconditional stability is obtained, for appropriate values of the regularization parameters, for both the hydrostatic and non-hydrostatic cases. Furthermore, when these parameters take their optimal values, the stability behaviour of the normal modes is identical to that obtained from a semi-implicit discretization of the unregularized equations. © Crown Copyright 2006. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] Using an intensity-scale technique to assess the added benefit of high-resolution model precipitation forecastsATMOSPHERIC SCIENCE LETTERS, Issue 2 2006Marion P. Mittermaier Abstract Deterministic precipitation forecasts from the 12- and 4-km versions of the Unified Model (UM) were compared using an intensity-scale technique. Averaging raw model output is always recommended to minimise grid-scale errors. The retained detail in averaged 4-km forecasts produces an improved prediction of larger accumulations. © Crown Copyright 2006. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||