WorldWideScience

Sample records for cadherin-2 controls directional

  1. Nonchemical weed control: New Directions

    OpenAIRE

    Melander, Bo

    2004-01-01

    The chapter reviews the most recent research on non-chemical weed control methods for field crops and highlights new technologies that might improve current physical weed control methods and probably lead to new and even better methods

  2. Sensorless vector and direct torque control

    CERN Document Server

    Vas, Peter

    1998-01-01

    This is the first comprehensive book on sensorless high performance a.c. drives. It is essential reading for anyone interested in acquiring a solid background on sensorless torque-controlled drives. It presents a detailed and unified treatment of sensorless vector-controlled and direct-torque controlled drive systems. It also discusses the applications of artificial intelligence to drives. Where possible, space vector theory is used and emphasis is laid on detailed mathematical and physical analysis. Sensorless drive schemes for different types of permanent magnet synchronous motors, synchronous reluctance motors, and induction motors are also presented. These include more than twenty vector drives e.g. five types of MRAS-based vector drives, and eleven types of direct-torque-controlled (DTC) drives, e.g. the ABB DTC drive. However, torque-controlled switched reluctance motor drives are also discussed due to their emerging importance. The book also covers various drive applications using artificial intellige...

  3. Direct torque control of permanent magnet drives

    Energy Technology Data Exchange (ETDEWEB)

    French, C.; Acarnley, P. [Univ. of Newcastle upon Tyne (United Kingdom)

    1995-12-31

    Many permanent magnet motor drives use an open loop form of torque control, based on the assumption that output torque is proportional to applied current. In a practical motor this assumption may not always be correct, due to sub-optimal alignment of magnets, non-uniformity of magnetic material, current sensor non-linearities and current controller limitations. These factors, together with non-optimized current references, can lead to high values of torque ripple and copper loss. This paper describes a method of estimating the electro-magnetic torque from the rate of change of co-energy with respect to position, thus taking account of mutual torque, reluctance torque and saturation effects. The paper shows how the estimator can be used in a direct torque control scheme. The direct torque controller maximizes the torque:copper loss ratio. Implementation of the direct torque controller in a DSP based drive system is described, with steady-state and transient experimental results illustrating the effectiveness of the direct torque control scheme.

  4. Climate modification directed by control theory

    CERN Document Server

    Liang, Wang

    2008-01-01

    Climate modification measures to counteract global warming receive some more new attentions in these years. Most current researches only discuss the impact of these measures to climate, but how to design such a climate regulator is still unknown. This paper shows the control theory could give the systematic direction for climate modification. But the control analyzing also reveals that climate modifications should only be regarded as a last-ditch measure.

  5. A directional spotlight baffle for control cabins

    Science.gov (United States)

    Anderson, K. W.; Clark, B. A. J.

    1980-10-01

    Direct overhead lighting in control cabins frequently gives rise to unwanted bright images of the luminaries in the windows and these images may degrade the cabin operator's view of the external world. A directional baffle incorporating light traps which allow a high ratio of wanted to unwanted illumination from a specific conventional spotlamp is described. In practical tests, images from the spotlamp baffle combination were practically inconspicuous both in day and night conditions. A general method of design is described for extension of the principle to other types of spotlamps.

  6. Direct Torque Control of the Asynchronous Motor

    Directory of Open Access Journals (Sweden)

    Peter Girovský

    2008-05-01

    Full Text Available This contribution deals with the proposal of direct torque control (DTC of asynchronous motor (AMwith the help of fuzzy logic. The whole structure of DTC is designed in software Matlab – Simulink, the fuzzy regulator is designed with the help of Fuzzy Toolbox. The results of DTC with fuzzy regulator are compared with DTC with the help of Depenbrock method and DTC with the help of Takahashi method.

  7. Direct Torque Control of the Asynchronous Motor

    OpenAIRE

    Peter Girovský; Jaroslava Žilková; Ľubomír Cibuľa; Jaroslav Timko

    2008-01-01

    This contribution deals with the proposal of direct torque control (DTC) of asynchronous motor (AM)with the help of fuzzy logic. The whole structure of DTC is designed in software Matlab – Simulink, the fuzzy regulator is designed with the help of Fuzzy Toolbox. The results of DTC with fuzzy regulator are compared with DTC with the help of Depenbrock method and DTC with the help of Takahashi method.

  8. Efficient Controlled Quantum Secure Direct Communication Protocols

    Science.gov (United States)

    Patwardhan, Siddharth; Moulick, Subhayan Roy; Panigrahi, Prasanta K.

    2016-07-01

    We study controlled quantum secure direct communication (CQSDC), a cryptographic scheme where a sender can send a secret bit-string to an intended recipient, without any secure classical channel, who can obtain the complete bit-string only with the permission of a controller. We report an efficient protocol to realize CQSDC using Cluster state and then go on to construct a (2-3)-CQSDC using Brown state, where a coalition of any two of the three controllers is required to retrieve the complete message. We argue both protocols to be unconditionally secure and analyze the efficiency of the protocols to show it to outperform the existing schemes while maintaining the same security specifications.

  9. Asynchronous machines. Direct torque control; Machines asynchrones. Commande par controle direct de couple

    Energy Technology Data Exchange (ETDEWEB)

    Fornel, B. de [Institut National Polytechnique, 31 - Toulouse (France)

    2006-05-15

    The asynchronous machine, with its low cost and robustness, is today the most widely used motor to make speed variators. However, its main drawback is that the same current generates both the magnetic flux and the torque, and thus any torque variation creates a flux variation. Such a coupling gives to the asynchronous machine a nonlinear behaviour which makes its control much more complex. The direct self control (DSC) method has been developed to improve the low efficiency of the scalar control method and for the specific railway drive application. The direct torque control (DTC) method is derived from the DSC method but corresponds to other type of applications. The DSC and DTC algorithms for asynchronous motors are presented in this article: 1 - direct control of the stator flux (DSC): principle, flux control, torque control, switching frequency of the inverter, speed estimation; 2 - direct torque control (DTC): principle, electromagnetic torque derivative, signals shape and switching frequency, some results, DTC speed variator without speed sensor, DTC application to multi-machine multi-converter systems; 3 - conclusion. (J.S.)

  10. Environmental controls: Market incentives v. direct regulation

    Energy Technology Data Exchange (ETDEWEB)

    Kosobud, R.F.; Atallah, D.S. [Univ. of Illinois, Chicago, IL (United States)

    1996-12-31

    Cap-and-trade environmental markets, where the commodities are tradable pollution rights, are being introduced in several closely watched applications as a potentially more cost-effective way of cleaning up the environment than direct or command-and-control (CAC) regulation. In this study, we examine the evidence on control cost savings provided by price and transactions data from the first few years of activity in two markets designed to reduce atmospheric pollution. Some observers of both markets have argued that prices for tradable permits lower than expected, and transactions fewer than expected, are evidence that the markets are not achieving the hoped for savings. It was found, on the contrary, that observed prices point toward more flexible and improved pollution control choices and that the number of transactions has been steadily increasing as market incentives are incorporated into enterprise decisions. These new markets during their first few years are generating, according to our estimates, control cost savings in the neighborhood of one to two billion dollars annually. However, there is evidence that the markets have not yet reached their full potential. In the course of this study, several obstacles to market performance were found that are worthy of attention by policy makers. 13 refs., 4 figs., 1 tab.

  11. Cadherin 2/4 signaling via PTP1B and catenins is crucial for nucleokinesis during radial neuronal migration in the neocortex

    Science.gov (United States)

    Martinez-Garay, Isabel; Gil-Sanz, Cristina; Franco, Santos J.; Espinosa, Ana; Molnár, Zoltán

    2016-01-01

    Cadherins are crucial for the radial migration of excitatory projection neurons into the developing neocortical wall. However, the specific cadherins and the signaling pathways that regulate radial migration are not well understood. Here, we show that cadherin 2 (CDH2) and CDH4 cooperate to regulate radial migration in mouse brain via the protein tyrosine phosphatase 1B (PTP1B) and α- and β-catenins. Surprisingly, perturbation of cadherin-mediated signaling does not affect the formation and extension of leading processes of migrating neocortical neurons. Instead, movement of the cell body and nucleus (nucleokinesis) is disrupted. This defect is partially rescued by overexpression of LIS1, a microtubule-associated protein that has previously been shown to regulate nucleokinesis. Taken together, our findings indicate that cadherin-mediated signaling to the cytoskeleton is crucial for nucleokinesis of neocortical projection neurons during their radial migration. PMID:27151949

  12. Fine mapping of the hereditary haemorrhagic telangiectasia (HHT3 locus on chromosome 5 excludes VE-Cadherin-2, Sprouty4 and other interval genes

    Directory of Open Access Journals (Sweden)

    Govani Fatima S

    2010-08-01

    Full Text Available Abstract Background There is significant interest in new loci for the inherited condition hereditary haemorrhagic telangiectasia (HHT because the known disease genes encode proteins involved in vascular transforming growth factor (TGF-β signalling pathways, and the disease phenotype appears to be unmasked or provoked by angiogenesis in man and animal models. In a previous study, we mapped a new locus for HHT (HHT3 to a 5.7 Mb region of chromosome 5. Some of the polymorphic markers used had been uninformative in key recombinant individuals, leaving two potentially excludable regions, one of which contained loci for attractive candidate genes encoding VE Cadherin-2, Sprouty4 and FGF1, proteins involved in angiogenesis. Methods Extended analyses in the interval-defining pedigree were performed using informative genomic sequence variants identified during candidate gene sequencing. These variants were amplified by polymerase chain reaction; sequenced on an ABI 3730xl, and analysed using FinchTV V1.4.0 software. Results Informative genomic sequence variants were used to construct haplotypes permitting more precise citing of recombination breakpoints. These reduced the uninformative centromeric region from 141.2-144 Mb to between 141.9-142.6 Mb, and the uninformative telomeric region from 145.2-146.9 Mb to between 146.1-146.4 Mb. Conclusions The HHT3 interval on chromosome 5 was reduced to 4.5 Mb excluding 30% of the coding genes in the original HHT3 interval. Strong candidates VE-cadherin-2 and Sprouty4 cannot be HHT3.

  13. Directional control of diffusion and swelling in megamolecular polysaccharide hydrogels.

    Science.gov (United States)

    Joshi, G; Okeyoshi, K; Okajima, M K; Kaneko, T

    2016-07-01

    Directional control of diffusion and swelling in megamolecular polysaccharide hydrogels is demonstrated by focusing on the anisotropic structures for water absorption. Due to the presence of a layered structure in the hydrogel, the directional control for diffusion parallel to the planar direction and swelling in the lateral direction are possible. PMID:27223843

  14. Circular Loudspeaker Array with Controllable Directivity

    DEFF Research Database (Denmark)

    Møller, Martin; Olsen, Martin; Agerkvist, Finn T.;

    2010-01-01

    Specific directivity patterns for circular arrays of loudspeakers can be achieved by utilizing the concept of phase-modes, which expands the directivity pattern into a series of circular harmonics. This paper investigates the applicability of this concept applied on a loudspeaker array on a...

  15. Reference model decomposition in direct adaptive control

    OpenAIRE

    Butler, H.; Honderd, G.; Amerongen, van, W.E.

    1991-01-01

    This paper introduces the method of reference model decomposition as a way to improve the robustness of model reference adaptive control systems (MRACs) with respect to unmodelled dynamics with a known structure. Such unmodelled dynamics occur when some of the nominal plant dynamics are purposely neglected in the controller design with the aim of keeping the controller order low. One of the effects of such undermodelling of the controller is a violation of the perfect model-matching condition...

  16. Post-directed weed control in squash

    Science.gov (United States)

    Organic squash (Cucurbita pepo L.) producers need appropriate herbicides that can effectively provide season- long weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of a potential organic herbicide on weed control efficacy, crop injury, and ...

  17. Simulink Model of Direct Torque Control of Induction Machine

    OpenAIRE

    H. F.A. Wahab; Sanusi, H.

    2008-01-01

    Direct torque control (DTC) is one of the most excellent control strategies of torque control in induction machine. It is considered as an alternative to the field oriented control (FOC) or vector control technique. These two control strategies are different on the operation principle but their objectives are the same. They aim to control effectively the torque and flux. Torque control of an induction machine based on DTC strategy has been developed and a comprehensive study is present in thi...

  18. Direct digital control of a bioreactor

    Czech Academy of Sciences Publication Activity Database

    Prell, Aleš; Šafář, Hynek; Švojgr, Miroslav; Sobotka, Miroslav

    Pardubice: University of Pardubice, 2000. s. 36. [International Scientific - Technical Conference Process Control 2000 /4./. 11.06.2000-14.06.2000, Kouty nad Desnou] Institutional research plan: CEZ:AV0Z5020903 Subject RIV: EI - Biotechnology ; Bionics

  19. Impaired goal-directed behavioural control in human impulsivity

    OpenAIRE

    Hogarth, Lee; Chase, Henry W.; Baess, Kathleen

    2010-01-01

    Two dissociable learning processes underlie instrumental behaviour. Whereas goal-directed behaviour is controlled by knowledge of the consequences, habitual behaviour is elicited directly by antecedent Pavlovian stimuli without knowledge of the consequences. Predominance of habitual control is thought to underlie psychopathological conditions associated with corticostriatal abnormalities, such as impulsivity and drug dependence. To explore this claim, smokers were assessed for nicotine depend...

  20. Improvements in direct torque control of induction motors

    OpenAIRE

    Arias Pujol, Antoni

    2001-01-01

    This thesis is mainly devoted to the investigation of speed control methods for three phase cage induction motors with particular emphasis being given to Direct Torque Control (DTC) improved techniques.Classical Direct Torque Control has inherent disadvantages such as: problems during starting resulting from the null states, the compulsory requirement of torque and flux estimators, and torque ripple. In the classical DTC induction motor drive a voltage vector is applied for the entire period,...

  1. Direct Torque Control of Matrix Converter Fed Induction Motor Drive

    OpenAIRE

    JAGADEESAN Karpagam; NIRMAL Kumar; MUTHUSAMY Suresh

    2011-01-01

    This paper presents the Direct TorqueControl (DTC) of induction motor drive using matrixconverters. DTC is a high performance motor controlscheme with fast torque and flux responses. However,the main disadvantage of conventional DTC iselectromagnetic torque ripple. In this paper, directtorque control for Induction Motors using MatrixConverters is analysed and points out the problem ofthe electromagnetic torque ripple which is one of themost important drawbacks of the Direct TorqueControl. Bes...

  2. Proposed Voltage Vector to Optimize Efficiency of Direct Torque Control

    OpenAIRE

    Goh Wee Yen; Ali Monadi; Nik Rumzi Nik Idris; Auzani Jidin; Tole Sutikno

    2014-01-01

    Compared to field-oriented control (FOC) system, direct torque control (DTC) system has gained attractiveness in control drive system because of its simpler control structure and faster dynamic control. However, supplying the drive system with rated flux at light load will decrease the power factor and efficiency of the system. Thus, an optimal flux has been applied during steady-state in order to maximize the efficiency of drive system. But when a torque is suddenly needed, for example durin...

  3. Direct adaptive control for nonlinear uncertain dynamical systems

    Science.gov (United States)

    Hayakawa, Tomohisa

    In light of the complex and highly uncertain nature of dynamical systems requiring controls, it is not surprising that reliable system models for many high performance engineering and life science applications are unavailable. In the face of such high levels of system uncertainty, robust controllers may unnecessarily sacrifice system performance whereas adaptive controllers are clearly appropriate since they can tolerate far greater system uncertainty levels to improve system performance. In this dissertation, we develop a Lyapunov-based direct adaptive and neural adaptive control framework that addresses parametric uncertainty, unstructured uncertainty, disturbance rejection, amplitude and rate saturation constraints, and digital implementation issues. Specifically, we consider the following research topics; direct adaptive control for nonlinear uncertain systems with exogenous disturbances; robust adaptive control for nonlinear uncertain systems; adaptive control for nonlinear uncertain systems with actuator amplitude and rate saturation constraints; adaptive reduced-order dynamic compensation for nonlinear uncertain systems; direct adaptive control for nonlinear matrix second-order dynamical systems with state-dependent uncertainty; adaptive control for nonnegative and compartmental dynamical systems with applications to general anesthesia; direct adaptive control of nonnegative and compartmental dynamical systems with time delay; adaptive control for nonlinear nonnegative and compartmental dynamical systems with applications to clinical pharmacology; neural network adaptive control for nonlinear nonnegative dynamical systems; passivity-based neural network adaptive output feedback control for nonlinear nonnegative dynamical systems; neural network adaptive dynamic output feedback control for nonlinear nonnegative systems using tapped delay memory units; Lyapunov-based adaptive control framework for discrete-time nonlinear systems with exogenous disturbances

  4. An Intuitive Definition of Demand Flexibility in Direct Load Control

    DEFF Research Database (Denmark)

    Tahersima, Fatemeh; Madsen, Per Printz; Andersen, Palle

    2013-01-01

    Two control approaches: direct and indirect control of demand side energy management in a smart grid are studied. Indirect control of energy demands is based on economic incentives. In this approach, consumers will shift their energy consumption with the benefit of a cut down in the electricity...

  5. Controlled and secure direct communication using GHZ state and teleportation

    International Nuclear Information System (INIS)

    A theoretical scheme for controlled and secure direct communication is proposed. The communication is based on GHZ state and controlled quantum teleportation. After insuring the security of the quantum channel (a set of qubits in the GHZ state), alice encodes the secret message directly on a sequence of particle states in the GHZ state and transmits them to Bob, supervised by Charlie using controlled quantum teleportation. Bob can read out the encoded messages directly by the measurement on his qubits. In this scheme, the controlled quantum teleportation transmits alice's message without revealing any information to a potential eavesdropper. Because there is not a transmission of the qubit carrying the secret messages between Alice and Bob in the public channel, it is completely secure for controlled and direct secret communication if a perfect quantum channel is used. The feature of this scheme is that the communication between two sides depends on the agreement of a third side. (orig.)

  6. Direct voltage control of magnetorheological damper for vehicle suspensions

    International Nuclear Information System (INIS)

    The paper presents a study on the direct voltage control of a magnetorheological (MR) damper for application in vehicle suspensions. As MR damper dynamics is highly nonlinear, the direct control system design for an MR damper is difficult. Representing an MR damper by a Takagi–Sugeno (TS) fuzzy model enables the linear control theory to be directly applied to design the MR damper controller. In this paper, first the MR damper dynamics is represented by a TS fuzzy model, and then an H∞ controller that considers the suspension performance requirements and the constraint on the input voltage for the MR damper is designed. Furthermore, considering the case that not all the state variables are measurable in practice, the design of an H∞ observer with immeasurable premise variables and the design of a robust controller are proposed, respectively. Numerical simulations are used to validate the effectiveness of the proposed approaches. (paper)

  7. DIRECT TORQUE CONTROL FOR INDUCTION MOTOR USING INTELLIGENT TECHNIQUES

    Directory of Open Access Journals (Sweden)

    R.Toufouti

    2007-09-01

    Full Text Available In this paper, we propose two approach intelligent techniques of improvement of Direct Torque Control (DTC of Induction motor such as fuzzy logic (FL and artificial neural network (ANN, applied in switching select voltage vector .The comparison with conventional direct torque control (DTC, show that the use of the DTC_FL and DTC_ANN, reduced the torque, stator flux, and current ripples. The validity of the proposed methods is confirmed by the simulative results.

  8. DIRECT TORQUE CONTROL FOR INDUCTION MOTOR USING INTELLIGENT TECHNIQUES

    OpenAIRE

    R. Toufouti; S.Meziane; Benalla, H.

    2007-01-01

    In this paper, we propose two approach intelligent techniques of improvement of Direct Torque Control (DTC) of Induction motor such as fuzzy logic (FL) and artificial neural network (ANN), applied in switching select voltage vector .The comparison with conventional direct torque control (DTC), show that the use of the DTC_FL and DTC_ANN, reduced the torque, stator flux, and current ripples. The validity of the proposed methods is confirmed by the simulative results.

  9. Direct torque control of induction machine under square wave conditions

    Energy Technology Data Exchange (ETDEWEB)

    Chapuis, Y.A.; Pelissou, C.; Roye, D. [E.N.S.I.E.G., St. Martin d`Heres (France). Lab. d`Electrotechnique de Grenoble

    1995-12-31

    The authors of this paper present the direct torque control (DTC) under square wave conditions. After describing the principles of the control system at high speed, they propose a control structure under square wave operation to optimize power and losses in the inverter and the machine. A transition method allowing transient problems between the two control modes to be minimized, is presented. Finally, they estimate the structure of the proposal by simulating good results on torque control obtained during square wave passage and up to very high machine speeds. They validate the control system at high speed by DSP implementation and experimental results.

  10. Combined vector control and direct torque control method for high performance induction motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Vaez-Zadeh, S.; Jalali, E. [Advanced Motion Systems Research Laboratory, School of Electrical and Computer Engineering, Faculty of Engineering, University of Tehran, North Kargar Ave., P.O. Box 14395/515, Tehran (Iran)

    2007-12-15

    A new control method is proposed for three phase high performance induction motor drives. The control system enjoys the advantages of vector control and direct torque control and avoids some of the implementation difficulties of either of the two control methods. In particular, the proposed control system includes a current vector control in connection with a switching table. An extensive comparative performance evaluation of a motor under the proposed control method confirms the effectiveness of the method and its partial superiority over either vector control or direct torque control despite its relative structural simplicity. (author)

  11. Combined vector control and direct torque control method for high performance induction motor drives

    International Nuclear Information System (INIS)

    A new control method is proposed for three phase high performance induction motor drives. The control system enjoys the advantages of vector control and direct torque control and avoids some of the implementation difficulties of either of the two control methods. In particular, the proposed control system includes a current vector control in connection with a switching table. An extensive comparative performance evaluation of a motor under the proposed control method confirms the effectiveness of the method and its partial superiority over either vector control or direct torque control despite its relative structural simplicity

  12. Controlled Bidirectional Quantum Direct Communication by Using a GHZ State

    Institute of Scientific and Technical Information of China (English)

    MAN Zhong-Xiao; XIA Yun-Jie

    2006-01-01

    @@ A controlled bidirectional quantum secret direct communication scheme is proposed by using a Greenberger-Horne-Zeilinger (GHZ) state. In the scheme, two users can exchange their secret messages simultaneously with a set of devices under the control of a third party. The security of the scheme is analysed and confirmed.

  13. Design and Comparison Direct Torque Control Techniques for Induction Motors

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Kazmierkowski, Marian P.; Zelechowski, Marcin;

    2005-01-01

    In this paper a comparison of two significant control methods of induction motor are presented. The first one is a classical Direct Torque and Flux Control (DTC) and is compared with a scheme, which uses Space Vector Modulator (DTC-SVM). A comparison in respect to dynamic and steady state...

  14. A Direct Feedback Control Based on Fuzzy Recurrent Neural Network

    Institute of Scientific and Technical Information of China (English)

    李明; 马小平

    2002-01-01

    A direct feedback control system based on fuzzy-recurrent neural network is proposed, and a method of training weights of fuzzy-recurrent neural network was designed by applying modified contract mapping genetic algorithm. Computer simul ation results indicate that fuzzy-recurrent neural network controller has perfect dynamic and static performances .

  15. Controlled Quantum N-Party Simultaneous Direct Communication

    Institute of Scientific and Technical Information of China (English)

    XIA Yun-Jie; MAN Zhong-Xiao

    2007-01-01

    In this paper, we propose a controlled quantum N-party simultaneous direct communication protocol with single-qubit measurements. Many users can simultaneously exchange their secret messages in a set of devices with the control of a supervisor. The eavesdropper's commonly used attacks can be detected through two security checking processes.

  16. Direct Torque Control Schemes for Split-Phase Induction Machine

    OpenAIRE

    Hatua, Kamalesh; Ranganathan, VT

    2004-01-01

    In this paper, DTC (Direct Torque Control) algorithms for Split-phase Induction Machine (SPIM) are established. SPIM has two sets of three-phase stator windings, with a shift of thirty electrical degrees between them. The significant contributions of the present work are: a) Two new methods of DTC technique for SPIM are developed. They are called as Resultant Flux Control Method and Individual Flux Control Method. b) Advantages and disadvantages of both the methods are discussed. High torque ...

  17. Fuzzy Based Stator Flux Optimizer Design For Direct Torque Control

    OpenAIRE

    Korkmaz, Fatih; Cakir, M. Faruk; Korkmaz, Yilmaz; Topaloglu, Ismail

    2012-01-01

    Direct Torque Control (DTC) is well known as an effective control technique for high performance drives in a wide variety of industrial applications and conventional DTC technique uses two constant reference value: torque and stator flux. In this paper, a new fuzzy based stator flux optimizer has been proposed for DTC controlled induction motor drivers and simulation studies have been carried out with Matlab/Simulink to compare the proposed system behaviours at vary load conditions. The most ...

  18. Control of VTOL Vehicles with Thrust-direction Tilting

    OpenAIRE

    Hua, Minh-Duc; Hamel, Tarek; Samson, Claude

    2013-01-01

    An approach to the control of a VTOL vehicle equipped with complementary thrust-direction tilting capabilities that nominally yield full actuation of the vehicle's position and attitude is developed. The particularity and difficulty of the control problem are epitomized by the existence of a maximal thrust-tilting angle which forbids complete and decoupled control of the vehicle's position and attitude in all situations. This problem is here addressed via the formalism of primary and secondar...

  19. Direct Torque Control of IPMSM to Improve Torque ripple and Efficiency based on Fuzzy Controller

    OpenAIRE

    B. Mirzaeian Dehkordi; H. Mostafavi; M. Ataie; M. Sadeghi Goghar

    2012-01-01

    In this paper, a stator-flux-reference frame control method is proposed in order to control the speed and torque of an Interior Permanent Magnet Synchronous Machine (IPMSM) in different loads condition. Direct Torque Control method (DTC) based on Space Vector Modulation (SVM) is used for control of IPMSM. In the proposed control method, conventional PI controller is used for controlling the stator flux, and torque of the motor. Also, a fuzzy controller is considered to improve the dynamic per...

  20. Direct torque control with feedback linearization for induction motor drives

    DEFF Research Database (Denmark)

    Lascu, Cristian; Jafarzadeh, Saeed; Fadali, Sami M.;

    2015-01-01

    This paper describes a Direct Torque Controlled (DTC) Induction Machine (IM) drive that employs feedback linearization and sliding-mode control. A feedback linearization approach is investigated, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitude....... This intuitive linear model is used to implement a DTC type controller that preserves all DTC advantages and eliminates its main drawback, the flux and torque ripple. Robust, fast, and ripple-free control is achieved by using Variable Structure Control (VSC) with proportional control in the vicinity of...... the sliding surface. The VSC component assures robustness as in DTC, while the proportional component eliminates the torque and flux ripple. The torque time response is similar to DTC and the proposed solution is flexible and highly tunable due to the proportional controller. The controller design and...

  1. Direct model reference adaptive control of a flexible robotic manipulator

    Science.gov (United States)

    Meldrum, D. R.

    1985-01-01

    Quick, precise control of a flexible manipulator in a space environment is essential for future Space Station repair and satellite servicing. Numerous control algorithms have proven successful in controlling rigid manipulators wih colocated sensors and actuators; however, few have been tested on a flexible manipulator with noncolocated sensors and actuators. In this thesis, a model reference adaptive control (MRAC) scheme based on command generator tracker theory is designed for a flexible manipulator. Quicker, more precise tracking results are expected over nonadaptive control laws for this MRAC approach. Equations of motion in modal coordinates are derived for a single-link, flexible manipulator with an actuator at the pinned-end and a sensor at the free end. An MRAC is designed with the objective of controlling the torquing actuator so that the tip position follows a trajectory that is prescribed by the reference model. An appealing feature of this direct MRAC law is that it allows the reference model to have fewer states than the plant itself. Direct adaptive control also adjusts the controller parameters directly with knowledge of only the plant output and input signals.

  2. Pixel extraction based integral imaging with controllable viewing direction

    International Nuclear Information System (INIS)

    We propose pixel extraction based integral imaging with a controllable viewing direction. The proposed integral imaging can provide viewers three-dimensional (3D) images in a very small viewing angle. The viewing angle and the viewing direction of the reconstructed 3D images are controlled by the pixels extracted from an elemental image array. Theoretical analysis and a 3D display experiment of the viewing direction controllable integral imaging are carried out. The experimental results verify the correctness of the theory. A 3D display based on the integral imaging can protect the viewer’s privacy and has huge potential for a television to show multiple 3D programs at the same time. (paper)

  3. Nonlinear Direct Robust Adaptive Control Using Lyapunov Method

    Directory of Open Access Journals (Sweden)

    Chunbo Xiu

    2013-07-01

    Full Text Available    The problem of robust adaptive stabilization of a class of multi-input nonlinear systems with arbitrary unknown parameters and unknown structure of bounded variation have been considered. By employing the direct adaptive and control Lyapunov function method, a robust adaptive controller is designed to complete the globally adaptive stability of the system states. By employing our result, a kind of nonlinear system is analyzed, the concrete form of the control law is given and the meaningful quadratic control Lyapunov function for the system is constructed. Simulation of parallel manipulator is provided to illustrate the effectiveness of the proposed method.

  4. Novel Design for Direct Torque Control System of PMSM

    OpenAIRE

    HUANG Xu-chao; LIN Rong-wen

    2013-01-01

    Nowadays, with the rapid development of high-performance servo system, The conventional permanent magnet synchronous motor (PMSM) Direct Torque Control (DTC) system has large torque ripple in low speed which cannot be well adapted to today`s development. The main reason is because the number of voltage vectors provided by the two-level inverter is only six and the relationship between voltage vector and torque is not clear[1-5.10-12]. In this paper, the basic concept of direct torque control ...

  5. Global Observer-based Attitude Controller Using Direct Inertial Measurements

    Directory of Open Access Journals (Sweden)

    Saâdi Bouhired

    2014-04-01

    Full Text Available In this work, we address the problem of global attitude control using direct inertial measurements. When using direct inertial measurement to observe the rigid body attitude, it is shown that due to a geometrical obstruction, it is impossible to achieve global asymptotic stability. In fact, for a particular initial condition the tracking error quaternion converges to a pure imaginary quaternion formed by an eigenvector of a characteristic matrix related to the inertial constant and known vectors. Our proposition consists of adding a dynamic signal to force the rigid body to escape from such a situation. The proposed observer-based controller is synthesized based on a single Lyapunov function and a stability analysis shows that the controller stabilizes globally and asymptotically the rigid body attitude at the desired one. The effectiveness of the proposed observer-based controller is confirmed by simulation results.

  6. Direct Torque Control of Induction Motor with Extended Kalman Filter

    OpenAIRE

    Pai, Dinesh A; Umanand, L; Rao, NJ

    2000-01-01

    Induction motor speed control is an area of research that has been in prominence for some time now. Recent advances in this field have made it possible to replace the DC motor by induction machines, even in applications that demand a fast dynamic response. Many industrial applications demand high performance speed sensorless operation due to various reasons. Direct torque control (DTC) of induction motors is a popular method because of the resulting fast dynamic response of the motor, lower s...

  7. IPMSM Motion-Sensorless Direct Torque and Flux Control

    DEFF Research Database (Denmark)

    Pitict, Christian Ilie; Andreescu, Gheorghe-Daniel; Blaabjerg, Frede;

    2005-01-01

    The paper presents a rather comprehensive implementation of a wide speed motion-sensorless control of IPMSM drives via direct torque and flux control (DTFC) with space vector modulation (SVM). Signal injection with only one D-module vector filter and phase-locked loop (PLL) observer is used at low...... provides for a smooth current waveform even at 1 rpm. The paper demonstrates through ample experiments a 1750 rpm 1 1 rpm speed range full-loaded with sensorless DTFC-SVM....

  8. Matrix converter controlled with the direct transfer function approach

    DEFF Research Database (Denmark)

    Rodriguez, J.; Silva, E.; Blaabjerg, Frede;

    2005-01-01

    power circuit, including the input filter. The power semiconductors are modelled as ideal bidirectional switches and the MC is controlled using a direct transfer function approach. The modulation strategy of the converter is explained in a complete and clear form. The commutation problem of two switches...

  9. Anger in School Managers: Continuity, Direction, Control and Style

    Science.gov (United States)

    Koc, Mustafa; Iskender, Murat; Cardak, Mehmet; Dusunceli, Betul

    2012-01-01

    School managers undertake an important duty in structuring of education institutions. In the study carried out in this context; anger conditions, continuity, and direction of anger, anger control levels and anger styles of school managers who are the decision makers in schools were examined according to the ages, working periods, duty types, ways…

  10. Polarization Controlled Directional Scattering for Nanoscopic Position Sensing

    CERN Document Server

    Neugebauer, Martin; Bag, Ankan; Leuchs, Gerd; Banzer, Peter

    2015-01-01

    Controlling the propagation and coupling of light to sub-wavelength antennas is a crucial prerequisite for many nanoscale optical devices. Recently, the main focus of attention has been directed towards high-refractive index materials such as silicon as an integral part of the antenna design. The development is motivated by the rich spectral properties of individual high-refractive index nanoparticles, featuring magnetic and electric resonances in the visible regime, whose interference may yield remarkably strong directivity. Here, we use tightly focused radially polarized light for controlled excitation of a spherical silicon nanoantenna. The resultant emission can be highly directional, depending on the antenna's position relative to the focus. This approach finds application as a novel position sensing technique, a discipline, which is of paramount importance in modern nanometrology, because of its special role in super-resolution microscopy. We yield a lateral resolution in the Angstrom regime.

  11. Improved Four-Switch BLDCM Direct Current Control

    Directory of Open Access Journals (Sweden)

    Pan Lei

    2013-08-01

    Full Text Available The main purpose of this study is to describe a low cost four-switch brushless dc motor (BLDCM drive. An improved direct current controlled scheme is designed and implemented to produce the desired dynamic and static current and speed characteristics. Eight voltage vectors are summarized, which are selected to control BLDCM in SVPWM pattern. This method avoids the undesired current distortion which is caused by uncontrollable phase. The operational principle of the four-switch BLDC motor drive and the developed control scheme are theoretically analyzed and the performance is demonstrated by both simulation and experimental results.

  12. Sensorless direct vector control of an induction motor

    Energy Technology Data Exchange (ETDEWEB)

    Menaa, M. [Laboratoire de Robotique Parallelisme et Electro-energetique, Departement d' Electrotechnique, Universite des Sciences et de la Technologie Houari Boumediene BP 32 EL Allia, Alger 16111, (Algeria); Touhami, O.; Ibtiouen, R. [Departement de Genie Electrique, Ecole Nationale polytechnique, 10 AV Pasteur, El-Harrach, Alger, (Algeria); Fadel, M. [Laboratoire d' Electrotechnique et d' Electronique Industrielle ENSEEIHT, Toulouse, 2 Rue Camichel BP 7122-31071 Cedex7, (France)

    2008-01-15

    In high-performance variable speed AC drive systems it is often important to accurately determine machine parameters and rotor speed values. An extended complex Kalman filter (ECKF) is used to estimate rotor resistance and mutual inductance without the use of a speed sensor. Such estimates are important in air gap flux orientation control. The ECKF is chosen over the more common extended Kalman filter based on the real-valued model as it is not as computationally intensive. The model of an induction machine obtained by the spiral vector theory and the ECKF are used to develop a new adaptive direct air gap flux orientation control with two sensors: one for the stator voltage and one for the stator current without Park transformation. The simulation tests show the effectiveness of the proposed adaptive direct air gap flux orientation control method. (Author)

  13. Torque Ripple Reduction in Direct Torque Control Based Induction Motor using Intelligent Controllers

    Science.gov (United States)

    Sudhakar, Ambarapu; Vijaya Kumar, M.

    2015-09-01

    This paper presents intelligent control scheme together with conventional control scheme to overcome the problems with uncertainties in the structure encountered with classical model based design of induction motor drive based on direct torque control (DTC). It allows high dynamic performance to be obtained with very simple hysteresis control scheme. Direct control of the torque and flux is achieved by proper selection of inverter voltage space vector through a lookup table. This paper also presents the application of intelligent controllers like neural network and fuzzy logic controllers to control induction machines with DTC. Intelligent controllers are used to emulate the state selector of the DTC. With implementation of intelligent controllers the system is also verified and proved to be operated stably with reduced torque ripple. The proposed method validity and effectiveness has been verified by computer simulations using Matlab/Simulink®. These results are compared with the ones obtained with a classical DTC using proportional integral speed controller.

  14. Data-Driven Predictive Direct Load Control of Refrigeration Systems

    DEFF Research Database (Denmark)

    Shafiei, Seyed Ehsan; Knudsen, Torben; Wisniewski, Rafal;

    2015-01-01

    A predictive control using subspace identification is applied for the smart grid integration of refrigeration systems under a direct load control scheme. A realistic demand response scenario based on regulation of the electrical power consumption is considered. A receding horizon optimal control is...... the control implementation. As an important practical consideration, the control design relies on a cheap solution with available measurements than using the expensive mass flow meters. The results show successful implementation of the method on a large-scale non-linear simulation tool which is...... validated against real data. The performance improvement results in a 22% reduction in the energy consumption. A comparative simulation is accomplished showing the superiority of the method over the existing approaches in terms of the load following performance....

  15. Direct Adaptive Aircraft Control Using Dynamic Cell Structure Neural Networks

    Science.gov (United States)

    Jorgensen, Charles C.

    1997-01-01

    A Dynamic Cell Structure (DCS) Neural Network was developed which learns topology representing networks (TRNS) of F-15 aircraft aerodynamic stability and control derivatives. The network is integrated into a direct adaptive tracking controller. The combination produces a robust adaptive architecture capable of handling multiple accident and off- nominal flight scenarios. This paper describes the DCS network and modifications to the parameter estimation procedure. The work represents one step towards an integrated real-time reconfiguration control architecture for rapid prototyping of new aircraft designs. Performance was evaluated using three off-line benchmarks and on-line nonlinear Virtual Reality simulation. Flight control was evaluated under scenarios including differential stabilator lock, soft sensor failure, control and stability derivative variations, and air turbulence.

  16. An Improved Fixed Switching Frequency Direct Torque Control of Induction Motor Drives Fed by Direct Matrix Converter

    OpenAIRE

    Taib, Nabil; Rekioua, Toufik; Francois, Bruno

    2010-01-01

    A few papers have been interested by the fixed switching frequency direct torque control fed by direct matrix converters, where we can find just the use of direct torque controlled space vector modulated method. In this present paper, we present an improved method used for a fixed switching frequency direct torque control (DTC) using a direct matrix converter (DMC). This method is characterized by a simple structure, a fixed switching frequency which causes minimal torque ripple and a unity i...

  17. Direct and Indirect Gradient Control for Static Optimisation

    Institute of Scientific and Technical Information of China (English)

    Yi Cao

    2005-01-01

    Static "self-optimising" control is an important concept, which provides a link between static optimisation and control[1]. According to the concept, a dynamic control system could be configured in such a way that when a set of certain variables are maintained at their setpoints, the overall process operation is automatically optimal or near optimal at steadystate in the presence of disturbances. A novel approach using constrained gradient control to achieve "self-optimisation" has been proposed by Cao[2]. However, for most process plants, the information required to get the gradient measure may not be available in real-time. In such cases, controlled variable selection has to be carried out based on measurable candidates. In this work, the idea of direct gradient control has been extended to controlled variable selection based on gradient sensitivity analysis (indirect gradient control). New criteria, which indicate the sensitivity of the gradient function to disturbances and implementation errors, have been derived for selection. The particular case study shows that the controlled variables selected by gradient sensitivity measures are able to achieve near optimal performance.

  18. Development of compact toroids injector for direct plasma controls

    International Nuclear Information System (INIS)

    The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 1021m-3. (orig.)

  19. Damping Force Tracking Control of MR Damper System Using a New Direct Adaptive Fuzzy Controller

    Directory of Open Access Journals (Sweden)

    Xuan Phu Do

    2015-01-01

    Full Text Available This paper presents a new direct adaptive fuzzy controller and its effectiveness is verified by investigating the damping force tracking control of magnetorheological (MR fluid based damper (MR damper in short system. In the formulation of the proposed controller, a model of interval type 2 fuzzy controller is combined with the direct adaptive control to achieve high performance in vibration control. In addition, H∞ (H infinity tracking technique is used in building a model of the direct adaptive fuzzy controller in which an enhanced iterative algorithm is combined with the fuzzy model. After establishing a closed-loop control structure to achieve high control performance, a cylindrical MR damper is adopted and damping force tracking results are obtained and discussed. In addition, in order to demonstrate the effectiveness of the proposed control strategy, two existing controllers are modified and tested for comparative work. It has been demonstrated from simulation and experiment that the proposed control scheme provides much better control performance in terms of damping force tracking error. This leads to excellent vibration control performance of the semiactive MR damper system associated with the proposed controller.

  20. Direct Torque Control of Induction Motor with Matrix Converter

    Directory of Open Access Journals (Sweden)

    Khalaf Salloum Gaeid

    2016-05-01

    Full Text Available The matrix converter (MC with direct torque control (DTC combination is efficient way to get better performance specifications in the industry. The MC and the DTC advantages are combined together. The reduction of complexity and cost of DC link in the DTC since it has no capacitors in the circuit. However, the controlling torque is a big problem it in DTC because of high ripple torque production which results in vibrations response in the operation of the iductuction motor as it has no PID to control the torque directly. To overcome this, a combination of MC with DTC is applied to reduce the fluctuation in the output torque and minimize the steady state error. This paper presents the simulation analysis of induction machine drives using Maltlab/Simulink toolbox R2012a. Design of DTC induction motor drive, MC with constant switching frequency, speed controller and stability investigation as well as controllability and observabilty with minimum final prediction (FPE steady state error and loss functionality has been carried out precisely.

  1. A Sensorless Direct Torque Control Scheme Suitable for Electric Vehicles

    OpenAIRE

    Khoucha, Farid; Marouani, Khoudir; Kheloui, Abdelaziz; Benbouzid, Mohamed

    2009-01-01

    In this paper a sensorless control is proposed to increase the efficiency of a Direct Torque Control (DTC) of an induction motor propelling an Electric Vehicle (EV). The proposed scheme uses an adaptive flux and speed observer that is based on a full order model of the induction motor. Moreover, it is evaluated on an EV global model taking into account the vehicle dynamics. Simulations were first carried out on a test vehicle propelled by a 37-kW induction motor to evaluate the consistency an...

  2. Maximum power point tracking control of direct methanol fuel cells

    Science.gov (United States)

    Zhang, Mingbo; Yan, Ting; Gu, Jinguang

    2014-02-01

    The performance of a direct methanol fuel cell (DMFC) is closely related to its operating conditions, and there is a specific combination of operating conditions at which the DMFC produces maximum power. Working at the maximum power point (MPP) can lower the methanol crossover rate and ancillary power consumption, improving the global efficiency of the system. The fuzzy controller proposed in this paper provides a simple and robust way to keep the DMFC working at the MPP by adjusting the operating conditions followed by the variation of the driven load in real time. Simulation shows that the fuzzy control approach can yield satisfactory results.

  3. The induction machine with direct stator flux and torque control

    Energy Technology Data Exchange (ETDEWEB)

    Richter, S. [Technische Hochschule Darmstadt (Germany). Inst. fuer Elektrische Energiewandlung

    1995-12-31

    The direct stator flux and torque control methods of Depenbrock and Takahashi allow an induction motor to operate with the same high dynamic performance as a DC motor. Both stator flux and torque are guided within a hysteresis-band around the desired value by means of two-position controllers whose outputs directly determine the actual voltage vector feeding the machine. Following a general analytical approach, this paper shows the relation between the hysteresis-band widths and torque pulsations, current harmonics and inverter switching frequency. As a result, the utilization of the restricted inverter switching frequency can be predicted and optimized dependent on speed, load and the parameters of the motor. 5 refs, 11 figs

  4. High performance direct instantaneous power control of PWM rectifiers

    International Nuclear Information System (INIS)

    This paper presents a new direct instantaneous power control (DPC) strategy for active rectifiers. In this novel scheme the PWM modulator has been utilized instead of the hysteresis comparators and switching table. The required converter voltage in each sampling period is directly calculated based on the reference and measured values of powers, system parameters, and the measured voltage of the AC source through simple equations which are wisely compensated for variations of the grid voltage during a sampling period. Then, the PWM generator generates the switching pulses for the voltage source converter. It is shown that the proposed DPC-PWM exhibits several features, such as a simple algorithm, constant switching frequency, robust to sampling frequency changes, robust to inductance values mismatch, and particularly it provides low sampling frequency. Extensive simulation and experimental results have proven the excellent performance and verify the validity and effectiveness of the proposed instantaneous power control scheme.

  5. Information Modeling for Direct Control of Distributed Energy Resources

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Andersen, Palle; Stoustrup, Jakob; Hansen, Lars Henrik; Victor Tackie, David

    We present an architecture for an unbundled liberalized electricity market system where a virtual power plant (VPP) is able to control a number of distributed energy resources (DERs) directly through a two-way communication link. The aggregator who operates the VPP utilizes the accumulated flexib...... whole range of different DERs. The devised information model can serve as input to the international standardization efforts on distributed energy resources.......We present an architecture for an unbundled liberalized electricity market system where a virtual power plant (VPP) is able to control a number of distributed energy resources (DERs) directly through a two-way communication link. The aggregator who operates the VPP utilizes the accumulated...

  6. Direct drive digital servo press with high parallel control

    Science.gov (United States)

    Murata, Chikara; Yabe, Jun; Endou, Junichi; Hasegawa, Kiyoshi

    2013-12-01

    Direct drive digital servo press has been developed as the university-industry joint research and development since 1998. On the basis of this result, 4-axes direct drive digital servo press has been developed and in the market on April of 2002. This servo press is composed of 1 slide supported by 4 ball screws and each axis has linearscale measuring the position of each axis with high accuracy less than μm order level. Each axis is controlled independently by servo motor and feedback system. This system can keep high level parallelism and high accuracy even with high eccentric load. Furthermore the 'full stroke full power' is obtained by using ball screws. Using these features, new various types of press forming and stamping have been obtained by development and production. The new stamping and forming methods are introduced and 'manufacturing' need strategy of press forming with high added value and also the future direction of press forming are also introduced.

  7. Direct Torque Control of a Permanent Magnet synchronous Motor

    OpenAIRE

    Ocen, David

    2005-01-01

    This work presents an improved variant of the Direct Torque Control (DTC) for a Permanent Magnet Synchronous Motor (PMSM). The improved DTC use a higher number of voltage space vectors by introducing a kind of Space Vector Modulation technique. The higher number of space vectors are tabulated in more precise switch tables which also take the emf induced in the stator windings into account. The emf voltage significantly affect the motor behavior from a given space vector. It is discussed how t...

  8. Predictive Direct Torque Control for Flux and Torque Ripple Reduction

    OpenAIRE

    Beerten, Jef; Verveckken, Jan; Driesen, Johan

    2010-01-01

    In this paper, a prediction scheme is presented to diminish both the torque and flux ripples in a direct torque control (DTC) induction motor drive. In a discrete implementation of the classical DTC scheme, the time delay associated with data processing results in additional torque and flux ripples. This part of the ripples can amount to a significant fraction of the overall ripple if the hysteresis bands are comparable to the maximum torque and flux variations in one sampling interval. This ...

  9. INDUCTION MOTOR DIRECT TORQUE CONTROL – FUZZY LOGIC CONTRIBUTION

    OpenAIRE

    CHIKHI, ABDESLEM; CHIKHI, KHALED; BELKACEM, SEBTI

    2012-01-01

    In this article we present the simulation results of the induction motor speed regulation by the direct torque control with a classic PI regulator. The MATLAB SIMULINK programming environment is used as a simulation tool. The results obtained, using a fuzzy logic, shows the importance of this method in the improvement of the performance of such regulationKeywords: DTC, Induction motor, PI, Fuzzy logic, FLR( Fuzzy logic regulator)

  10. Direct torque control of brushless doubly-fed reluctance machines

    OpenAIRE

    Yu, Jian

    2004-01-01

    Theoretical and Experimental results of research on the Direct Torque Control (DTC) of the Brushless Doubly Fed Reluctance Machine (BDFRM) are presented in this thesis. The main motivation for this work has been found in the relative simplicity of the DTC strategy and attractive properties of the BDFRM drive, foremost its cost-effectiveness associated with the use of a partially rated power electronics, and reliability of brushless structure of the machine itself. It is hoped that the project...

  11. FPGA-Based Implementation Direct Torque Control of Induction Motor

    OpenAIRE

    Saber Krim; Soufien Gdaim; Abdellatif Mtibaa; Mohamed Faouzi Mimouni

    2015-01-01

    This paper proposes a digital implementation of the direct torque control (DTC) of an Induction Motor (IM) with an observation strategy on the Field Programmable Gate Array (FPGA). The hardware solution based on the FPGA is caracterised by fast processing speed due to the parallel processing. In this study the FPGA is used to overcome the limitation of the software solutions (Digital Signal Processor (DSP) and Microcontroller). Also, the DTC of IM has many drawbacks such as for example; The o...

  12. Information Modeling for Direct Control of Distributed Energy Resources

    OpenAIRE

    Biegel, Benjamin; Andersen, Palle; Stoustrup, Jakob; Hansen, Lars Henrik; Victor Tackie, David

    2013-01-01

    We present an architecture for an unbundledliberalized electricity market system where a virtual powerplant (VPP) is able to control a number of distributed energyresources (DERs) directly through a two-way communicationlink. The aggregator who operates the VPP utilizes the accumulated flexibility of the DERs to participate in the electricitymarket on equal terms with conventional power plants. Thefocus of this paper is the interface between the DERs and theVPP: this interface must enable the ...

  13. Percutaneous transhepatic cholangial drainage: direct approach under fluoroscopic control.

    Science.gov (United States)

    Takada, T; Hanyu, F; Kobayashi, S; Uchida, Y

    1976-01-01

    We devised a direct percutaneous transhepatic cholangial drainage under fluoroscopic control. The principle is as follows. After percutaneous transhepatic cholangiography, the three dimensional structure of intrahepatic bile ducts is projected to a two dimensional plane under fluoroscopy; the needle can then be introduced into the selected bile duct with accuracy. The technique can be used as a preoperative management of operations of patients with jaundice and also as a palliative management of advanced cancer without much complication. PMID:1249944

  14. Directional Control of Plasmon-Exciton interaction with Plexcitonic Crystals

    Science.gov (United States)

    Balci, Sinan; Karademir, Ertugrul; Kocabas, Coskun; Aydinli, Atilla

    2015-03-01

    Plexcitons are strongly coupled plasmon excitons modes. In this work, we developed a platform, consisting of one and two dimensional corrugated surface patterns coated with a thin metal film and a dye solution. This system shows a controlled coupling action based on the excitation direction of SPP modes. Our scheme is based on the control of wavelengths of the forbidden SPP modes. Three kinds of patterns have been tested; a one dimensional uniform, a triangular, and a square lattice type crystals. For all three cases, lowest wavelength of the band gap is observed in Γ to M direction. For triangular and square lattice cases, band gap center oscillates between two finite values for every 60° and 90°s, respectively. We utilized this behavior to control SPP and J-aggregate coupling. We observe directional dependence of Rabi splitting energy varying between 0 meV and 60 meV . Square lattice gives the ability to tune a larger band gap, whereas triangular lattice gives higher number of symmetry points. Simulations show that, an 80 nm deep triangular lattice with 280 nm periodicity can result in omnidirectional decoupling of plexcitons. TUBITAK, Grants 110T790, 110T589, and 112T091.

  15. Control range: a controllability-based index for node significance in directed networks

    International Nuclear Information System (INIS)

    While a large number of methods for module detection have been developed for undirected networks, it is difficult to adapt them to handle directed networks due to the lack of consensus criteria for measuring the node significance in a directed network. In this paper, we propose a novel structural index, the control range, motivated by recent studies on the structural controllability of large-scale directed networks. The control range of a node quantifies the size of the subnetwork that the node can effectively control. A related index, called the control range similarity, is also introduced to measure the structural similarity between two nodes. When applying the index of control range to several real-world and synthetic directed networks, it is observed that the control range of the nodes is mainly influenced by the network's degree distribution and that nodes with a low degree may have a high control range. We use the index of control range similarity to detect and analyze functional modules in glossary networks and the enzyme-centric network of homo sapiens. Our results, as compared with other approaches to module detection such as modularity optimization algorithm, dynamic algorithm and clique percolation method, indicate that the proposed indices are effective and practical in depicting structural and modular characteristics of sparse directed networks

  16. Direct Vector Control of Induction Motor Based on Sinusoidal PWM Inverter with Fuzzy Logic Controller

    Directory of Open Access Journals (Sweden)

    Nirban Chakraborty

    2014-04-01

    Full Text Available This paper presents the speed control scheme of direct vector control of Induction Motor drive (IM drive. The Fuzzy logic controller is (FLC used as the controller part here for the direct vector control of Induction Motor using Sinusoidal PWM Inverter (SPWM. Fuzzy logic controller has become a very popular controlling scheme in the field of Industrial application. The entire module of this IM is divided into several parts such as IM body module, Inverter module, coordinate transformation module and Sinusoidal pulse width modulation (SPWM production module and so on. With the help of this module we can analyze a variety of different simulation waveforms, which provide an effective means for the analysis and design of the IM control system using FLC technique.

  17. Comparison of three-level torque hysteresis controllers for direct torque control

    OpenAIRE

    Beerten, Jef; Verveckken, Jan; Driesen, Johan

    2009-01-01

    In this paper, a comparison is made between different implementations of the three-level torque comparator for a Direct Torque Control (DTC) based induction motor drive. The DTC scheme controls stator flux and torque by means of hysteresis comparators, respectively a two-level control structure for the stator flux and a three-level comparator for the electromagnetic torque. The standard three-level hysteresis controller has a DC offset torque error. In this paper, an additive implementation i...

  18. Direct Torque Control System for a Three Phase Induction Motor With Fuzzy Logic Based Speed Controller

    OpenAIRE

    Turki Y. Abdalla; Haroution Antranik Hairik; Adel M. Dakhil

    2010-01-01

    This paper presents a method for improving the speed profile of a three phase induction motor in direct torque control (DTC) drive system using a proposed fuzzy logic based speed controller. A complete simulation of the conventional DTC and closed-loop for speed control of three phase induction motor was tested using well known Matlab/Simulink software package. The speed control of the induction motor is done by using the conventional proportional integral (PI) cont...

  19. Control concepts for direct steam generation in parabolic troughs

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, Loreto; Zarza, Eduardo [CIEMAT, Plataforma Solar de Almeria, Tabernas (Almeria) (Spain); Berenguel, Manuel [Universidad de Almeria, Dept. de Lenguajes y Computacion, Almeria (Spain); Camacho, Eduardo F. [Universidad de Sevilla, Dept. de Ingenieria de Sistemas y Automatica, Sevilla (Spain)

    2005-02-01

    A new prototype parabolic-trough collector system was erected at the Plataforma Solar de Almeria (PSA) (1996-1998) to investigate direct steam generation (DSG) in a solar thermal power plant under real solar conditions. The system has been under evaluation for efficiency, cost, control and other parameters since 1999. The main objective of the control system is to obtain steam at constant temperature and pressure at the solar field outlet, so that changes in inlet water conditions and/or in solar radiation affect the amount of steam, but not its quality or the nominal plant efficiency. This paper presents control schemes designed and tested for two operating modes, 'Recirculation', for which a proportional-integral-derivative (PI/PID) control functions scheme has been implemented, and 'Once-through', requiring more complex control strategies, for which the scheme is based on proportional-integral (PI), feedforward and cascade control. Experimental results of both operation modes are discussed. (Author)

  20. Construction and direct electrochemistry of orientation controlled laccase electrode

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Key Laboratory of Colloid and Interface Chemistry of the Education Ministry of China, Shandong University, Jinan 250100 (China); Zhang, Jiwei [State Key Laboratory of Microbial Technology of China, Shandong University, Jinan 250100 (China); Huang, Xirong, E-mail: xrhuang@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry of the Education Ministry of China, Shandong University, Jinan 250100 (China); State Key Laboratory of Microbial Technology of China, Shandong University, Jinan 250100 (China); Wang, Tianhong, E-mail: wangtianhong@sdu.edu.cn [State Key Laboratory of Microbial Technology of China, Shandong University, Jinan 250100 (China)

    2014-03-28

    Highlights: • A recombinant laccase with Cys-6×His tag at the N or C terminus was generated. • Orientation controlled laccase electrodes were constructed via self assembly. • The electrochemical behavior of laccase electrodes was orientation dependent. • The C terminus tagged laccase was better for bioelectrocatalytic reduction of O{sub 2}. - Abstract: A laccase has multiple redox centres. Chemisorption of laccases on a gold electrode through a polypeptide tag introduced at the protein surface provides an isotropic orientation of laccases on the Au surface, which allows the orientation dependent study of the direct electrochemistry of laccase. In this paper, using genetic engineering technology, two forms of recombinant laccase which has Cys-6×His tag at the N or C terminus were generated. Via the Au-S linkage, the recombinant laccase was assembled orientationally on gold electrode. A direct electron transfer and a bioelectrocatalytic activity toward oxygen reduction were observed on the two orientation controlled laccase electrodes, but their electrochemical behaviors were found to be quite different. The orientation of laccase on the gold electrode affects both the electron transfer pathway and the electron transfer efficiency of O{sub 2} reduction. The present study is helpful not only to the in-depth understanding of the direct electrochemistry of laccase, but also to the development of laccase-based biofuel cells.

  1. Construction and direct electrochemistry of orientation controlled laccase electrode

    International Nuclear Information System (INIS)

    Highlights: • A recombinant laccase with Cys-6×His tag at the N or C terminus was generated. • Orientation controlled laccase electrodes were constructed via self assembly. • The electrochemical behavior of laccase electrodes was orientation dependent. • The C terminus tagged laccase was better for bioelectrocatalytic reduction of O2. - Abstract: A laccase has multiple redox centres. Chemisorption of laccases on a gold electrode through a polypeptide tag introduced at the protein surface provides an isotropic orientation of laccases on the Au surface, which allows the orientation dependent study of the direct electrochemistry of laccase. In this paper, using genetic engineering technology, two forms of recombinant laccase which has Cys-6×His tag at the N or C terminus were generated. Via the Au-S linkage, the recombinant laccase was assembled orientationally on gold electrode. A direct electron transfer and a bioelectrocatalytic activity toward oxygen reduction were observed on the two orientation controlled laccase electrodes, but their electrochemical behaviors were found to be quite different. The orientation of laccase on the gold electrode affects both the electron transfer pathway and the electron transfer efficiency of O2 reduction. The present study is helpful not only to the in-depth understanding of the direct electrochemistry of laccase, but also to the development of laccase-based biofuel cells

  2. Direct Torque Control of IPMSM to Improve Torque ripple and Efficiency based on Fuzzy Controller

    Directory of Open Access Journals (Sweden)

    B. Mirzaeian Dehkordi

    2012-09-01

    Full Text Available In this paper, a stator-flux-reference frame control method is proposed in order to control the speed and torque of an Interior Permanent Magnet Synchronous Machine (IPMSM in different loads condition. Direct Torque Control method (DTC based on Space Vector Modulation (SVM is used for control of IPMSM. In the proposed control method, conventional PI controller is used for controlling the stator flux, and torque of the motor. Also, a fuzzy controller is considered to improve the dynamic performance of DTC technique for speed control. In comparison to the conventional reference flux controller methods, this method, in addition, improves the torque profile of the motor drive. Moreover, it reduces copper losses. Simulation results for a 240V, 120A, 2500rpm, IPMSM confirm the appropriate performances of the method.

  3. Direct Torque Control System for a Three Phase Induction Motor With Fuzzy Logic Based Speed Controller

    Directory of Open Access Journals (Sweden)

    Turki Y. Abdalla

    2010-12-01

    Full Text Available This paper presents a method for improving the speed profile of a three phase induction motor in direct torque control (DTC drive system using a proposed fuzzy logic based speed controller. A complete simulation of the conventional DTC and closed-loop for speed control of three phase induction motor was tested using well known Matlab/Simulink software package. The speed control of the induction motor is done by using the conventional proportional integral (PI controller and the proposed fuzzy logic based controller. The proposed fuzzy logic controller has a nature of (PI to determine the torque reference for the motor. The dynamic response has been clearly tested for both conventional and the proposed fuzzy logic based speed controllers. The simulation results showed a better dynamic performance of the induction motor when using the proposed fuzzy logic based speed controller compared with the conventional type with a fixed (PI controller.

  4. Complete control, direct observation and study of molecular super rotors

    CERN Document Server

    Korobenko, Aleksey; Milner, Valery

    2013-01-01

    Extremely fast rotating molecules carrying significantly more energy in their rotation than in any other degree of freedom are known as "super rotors". It has been speculated that super rotors may exhibit a number of unique and intriguing properties. Theoretical studies showed that ultrafast molecular rotation may change the character of molecular scattering from solid surfaces, alter molecular trajectories in external fields, make super rotors surprisingly stable against collisions, and lead to the formation of gas vortices. New ways of molecular cooling and selective chemical bond breaking by ultrafast spinning have been proposed. Owing to the fundamental laws of nature, bringing a large number of molecules to fast, directional and synchronous rotation is rather challenging. As a result, only indirect evidence of super rotors has been reported to date. Here we demonstrate the first controlled creation, direct observation and study of molecular super rotors. Using intense laser pulses tailored to produce an ...

  5. Control of asynchronous motors. Volume 1. Modeling, vectorial control and direct torque control; Commande des moteurs asynchrones. Volume 1. Modelisation, controle vectoriel et DTC

    Energy Technology Data Exchange (ETDEWEB)

    Canudas de Wit, C. [Ecole Nationale Superieure d' Ingenieurs de Genie Chimique, ENSIGC, 31 - Toulouse (France)

    2000-07-01

    This first volume deals with the problems of control of asynchronous motors in industrial environments: industrial environment, variable speed, asynchronous motors and power supplies, modeling, direct torque control laws, control by controlled limit cycles under frequency constraints. (J.S.)

  6. Controlling Pattern Formation in Nanoparticle Assemblies via Directed Solvent Dewetting

    Science.gov (United States)

    Martin, Christopher P.; Blunt, Matthew O.; Pauliac-Vaujour, Emmanuelle; Stannard, Andrew; Moriarty, Philip; Vancea, Ioan; Thiele, Uwe

    2007-09-01

    We have achieved highly localized control of pattern formation in two-dimensional nanoparticle assemblies by direct modification of solvent dewetting dynamics. A striking dependence of nanoparticle organization on the size of atomic force microscope-generated surface heterogeneities is observed and reproduced in numerical simulations. Nanoscale features induce a rupture of the solvent-nanoparticle film, causing the local flow of solvent to carry nanoparticles into confinement. Microscale heterogeneities instead slow the evaporation of the solvent, producing a remarkably abrupt interface between different nanoparticle patterns.

  7. Controller Design for Direct Torque Controlled Space Vector Modulated (DTC-SVM) Induction Motor Drives

    DEFF Research Database (Denmark)

    Zelechowski, M.; Kazmierkowski, M.P.; Blaabjerg, Frede

    2005-01-01

    In this paper two different methods of PI controllers for direct torque controlled-space vector modulated induction motor drives have been studied. The first one is simple method based only on symmetric optimum criterion. The second approach takes into account the full model of induction motor in...

  8. STATOR FLUX OPTIMIZATION ON DIRECT TORQUE CONTROL WITH FUZZY LOGIC

    Directory of Open Access Journals (Sweden)

    Fatih Korkmaz

    2012-07-01

    Full Text Available The Direct Torque Control (DTC is well known as an effective control technique for high performance drives in a wide variety of industrial applications and conventional DTC technique uses two constant reference value: torque and stator flux. In this paper, fuzzy logic based stator flux optimization technique for DTC drives that has been proposed. The proposed fuzzy logic based stator flux optimizer self-regulates the stator flux reference using induction motor load situation without need of any motor parameters. Simulation studies have been carried out with Matlab/Simulink to compare the proposed system behaviors at vary load conditions. Simulation results show that the performance of the proposed DTC technique has been improved and especially at low-load conditions torque ripple are greatly reduced with respect to the conventional DTC.

  9. Direct digital control of furnaces irradiated in nuclear reactors

    International Nuclear Information System (INIS)

    An experimental direct digital control system has been realised in the 'C.E.N.G.', in order to verify that a computer makes easier the control of the experiments done in the nuclear reactors and to solve the theoretical and technical difficulties. The regulation is applied to thermal processes. The sampled data systems theory permits to choose the type of an efficient and simple digital compensator, and to establish a diagram which gives the values of the correcting parameters (obtained by minimizing the difference between the output and the input when perturbations occur). The programme execute, in simultaneity, supervision and regulation. Complex possibilities of printing out measures and alarms existed. The computer works out an incremental correction which makes step motors to turn. These motors act on the heating organs. The theoretical values and answers have been confirmed. The accuracy was limited essentially by the input quantification (1/1000 th). The comfort of such a system has been noticeable. (author)

  10. An Improved Fixed Switching Frequency Direct Torque Control of Induction Motor Drives Fed by Direct Matrix Converter

    CERN Document Server

    Taib, Nabil; Francois, Bruno

    2010-01-01

    A few papers have been interested by the fixed switching frequency direct torque control fed by direct matrix converters, where we can find just the use of direct torque controlled space vector modulated method. In this present paper, we present an improved method used for a fixed switching frequency direct torque control (DTC) using a direct matrix converter (DMC). This method is characterized by a simple structure, a fixed switching frequency which causes minimal torque ripple and a unity input power factor. Using this strategy, we combine the direct matrix converters advantages with those of direct torque control (DTC) schemes. The used technique for constant frequency is combined with the input current space vector to create the switching table of direct matrix converter (DMC). Simulation results clearly demonstrate a better dynamic and steady state performances of the proposed method.

  11. Optimization of a neural network based direct inverse control for controlling a quadrotor unmanned aerial vehicle

    OpenAIRE

    Heryanto M Ary; Wahab Wahidin; Kusumoputro Benyamin

    2015-01-01

    UAVs are mostly used for surveillance, inspection and data acquisition. We have developed a Quadrotor UAV that is constructed based on a four motors with a lift-generating propeller at each motors. In this paper, we discuss the development of a quadrotor and its neural networks direct inverse control model using the actual flight data. To obtain a better performance of the control system of the UAV, we proposed an Optimized Direct Inverse controller based on re-training the neural networks wi...

  12. Direct adaptive control for nonlinear uncertain system based on control Lyapunov function method

    Institute of Scientific and Technical Information of China (English)

    Chen Yimei; Han Zhengzhi; Tang Houjun

    2006-01-01

    The problem of adaptive stabilization of a class of multi-input nonlinear systems with unknown parameters both in the state vector-field and the input vector-field has been considered. By employing the control Lyapunov function method, a direct adaptive controller is designed to complete the global adaptive stability of the uncertain system. At the same time, the controller is also verified to possess the optimality. Example and simulations are provided to illustrate the effectiveness of the proposed method.

  13. Direct numerical simulation of vector-controlled free jets

    Energy Technology Data Exchange (ETDEWEB)

    Tsujimoto, K; Ao, K; Shakouchi, T; Ando, T, E-mail: tujimoto@mach.mie-u.ac.jp [Graduate School of Engineering, Mie University, Tsu, 514-8507 (Japan)

    2011-12-22

    We conduct DNS (direct numerical simulation) of vector controlled free jets. The inflow velocity of jet is periodically oscillated perpendicular to the jet axis. In order to realize the high accurate computation, a discretization in space is performed with hybrid scheme in which Fourier spectral and 6th order compact scheme are adopted. From visualized instantaneous vortex structures, it is found that the flow pattern considerably changes according to the oscillating frequency, i.e., according to the increasing the frequency, wave, bifurcating and flapping modes appear in turn. In order to quantify mixing efficiency under the vector control, as the mixing measure, statistical entropy is investigated. Compared to the uncontrolled jet, the mixing efficiency is improved in order of wavy, flapping and bifurcating modes. Thus the vector control can be expected for the improvement of mixing efficiency. Further to make clear the reason for the mixing enhancement, Snapshot POD and DMD method are applied. The primary flow structures under the vector control are demonstrated.

  14. Direct numerical simulation of vector-controlled free jets

    International Nuclear Information System (INIS)

    We conduct DNS (direct numerical simulation) of vector controlled free jets. The inflow velocity of jet is periodically oscillated perpendicular to the jet axis. In order to realize the high accurate computation, a discretization in space is performed with hybrid scheme in which Fourier spectral and 6th order compact scheme are adopted. From visualized instantaneous vortex structures, it is found that the flow pattern considerably changes according to the oscillating frequency, i.e., according to the increasing the frequency, wave, bifurcating and flapping modes appear in turn. In order to quantify mixing efficiency under the vector control, as the mixing measure, statistical entropy is investigated. Compared to the uncontrolled jet, the mixing efficiency is improved in order of wavy, flapping and bifurcating modes. Thus the vector control can be expected for the improvement of mixing efficiency. Further to make clear the reason for the mixing enhancement, Snapshot POD and DMD method are applied. The primary flow structures under the vector control are demonstrated.

  15. Novel Design for Direct Torque Control System of PMSM

    Directory of Open Access Journals (Sweden)

    HUANG Xu-chao

    2013-04-01

    Full Text Available Nowadays, with the rapid development of high-performance servo system, The conventional permanent magnet synchronous motor (PMSM Direct Torque Control (DTC system has large torque ripple in low speed which cannot be well adapted to today`s development. The main reason is because the number of voltage vectors provided by the two-level inverter is only six and the relationship between voltage vector and torque is not clear[1-5.10-12]. In this paper, the basic concept of direct torque control of permanent magnet synchronous motor is investigated in order to emphasize the effects produced by a given voltage vector on stator and torque variations in this paper. Modified the voltage sector switching table, a novel DTC scheme for the permanent magnet synchronous motor is proposed which is using a novel three-level inverter. An improvement of the drive performance can be obtained by using the novel DTC scheme. The simulation results showed that the scheme could reduce the torque ripple in low speed and improved the stability of the motor under the condition of keeping the system dynamic performance.

  16. Minimizing Segregation during the Controlled Directional Solidification of Dendric Alloys

    Science.gov (United States)

    Grugel, Richard N.; Fedoseyev, Alex; Kim, Shin-Woo

    2003-01-01

    Gravity-driven convection induced in the liquid by density gradients of temperature or composition disrupts uniform dendritic growth during controlled directional solidification and promotes severe macrosegregation. The solute-rich region about the dendrite tip appears to play a pivotal role in channel initiation. Allen and Hunt referred to this region as an "initial transient" or dynamic region constituting steep concentration gradients. Experimental investigation also point to the role the tip region plays in developing microstructure. Hellawell and co-workers showed that flow-through dendritic channels could be effectively disrupted, and segregation minimized, during the gradient freezing of bulk castings by rotating the melt through a slight angle with respect to Earth's gravity vector. Adapting this principle to controlled directional solidification, it has been shown" that segregation in dendritic alloys can be minimized, and properties improved, by processing the sample near horizontal in conjunction with a slow axial rotation of the crucible. It is postulated that the observed microstructural uniformity arises by maintaining the developing solute field about the dendrite tip. Solute rejected during vertical directional solidification will rise or sink parallel to the primary dendrite arms during axial rotation setting the stage for accumulation, instabilities, and segregation. In contrast, during horizontal growth, the rejected solute will sink or rise perpendicular to the primary dendrite. Now, in the presence of a slight axial rotation, solute that was initially sinking (or rising) will find itself above (or below) its parent dendrite, i.e., still about the tip region. The following is intended to experimentally demonstrate the viability of this concept in coordination with a model that gives predictive insight regarding solute distribution about growing dendrites. Alloys based on the lead-tin eutectic system were used in this study. The system is well

  17. Improved Torque Control Performance of Direct Torque Control for 5-Phase Induction Machine

    OpenAIRE

    Logan Raj Lourdes Victor Raj; Auzani Jidin; Kasrul Abdul Karim; Tole Sutikno; R. Sundram; Mohd Hatta Jopri

    2013-01-01

    In this paper, the control of five-phase induction machine using Direct Torque Control (DTC) is presented. The general D-Q model of five-phase induction machine is discussed. The de-coupled control of stator flux and electromagnetic torque based on hysteresis controller similar to conventional DTC is applied to maintain the simplicity of the system. Three sets of look-up tables consist of voltage vectors with different amplitude that selects the  most optimal voltage vectors according motor o...

  18. An improved Direct Adaptive Fuzzy controller for an uncertain DC Motor Speed Control System

    OpenAIRE

    Chunjie Zhou; Shuang Huang; Quan Yin; Duc Cuong Quach

    2013-01-01

    In this paper, we present an improved Direct Adaptive Fuzzy (IDAF) controller applied to general control DC motor speed system. In particular, an IDAF algorithm is designed to control an uncertain DC motor speed to track a given reference signal. In fact, the quality of the control system depends significantly on the amount of fuzzy rules-fuzzy sets and the updating coefficient of the adaptive rule. This can be observed clearly by the system error when the reference input is constant and out ...

  19. Diffusion imaging quality control via entropy of principal direction distribution.

    Science.gov (United States)

    Farzinfar, Mahshid; Oguz, Ipek; Smith, Rachel G; Verde, Audrey R; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C; Paterson, Sarah; Evans, Alan C; Styner, Martin A

    2013-11-15

    Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, "venetian blind" artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here called

  20. Direct Torque Control of Saturated Doubly-Fed Induction Generator using High Order Sliding Mode Controllers

    Directory of Open Access Journals (Sweden)

    Elhadj BOUNADJA

    2016-07-01

    Full Text Available The present work examines a direct torque control strategy using a high order sliding mode controllers of a doubly-fed induction generator (DFIG incorporated in a wind energy conversion system and working in saturated state. This research is carried out to reach two main objectives. Firstly, in order to introduce some accuracy for the calculation of DFIG performances, an accurate model considering magnetic saturation effect is developed. The second objective is to achieve a robust control of DFIG based wind turbine. For this purpose, a Direct Torque Control (DTC combined with a High Order Sliding Mode Control (HOSMC is applied to the DFIG rotor side converter. Conventionally, the direct torque control having hysteresis comparators possesses major flux and torque ripples at steady-state and moreover the switching frequency varies on a large range. The new DTC method gives a perfect decoupling between the flux and the torque. It also reduces ripples in these grandeurs. Finally, simulated results show, accurate dynamic performances, faster transient responses and more robust control are achieved.

  1. Future directions for arms control and nonproliferation. Conference summary

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-06

    This report provides a summary of the presentations and discussions at the Spring 1994 CNSN-Wilton Park Conference. The Conference was one of a series on US-European security cooperation organized by The Center for National Security Negotiations (CNSN) of Science Applications International Corporation. These conferences bring together government and non-government experts, primarily from the United States and Europe, to discuss a range of regional and global security issues. The conferences provide an opportunity to explore, in a frank and off-the-record environment, common interests and concerns, as well as differences in approach that affect trans-Atlantic cooperation. This report is divided into the following three areas: (1) implementation of existing and pending agreements; (2) non-proliferation: prospects for trans-Atlantic cooperation; and (3) future directions in arms control.

  2. Improved direct torque control of induction motor with dither injection

    Indian Academy of Sciences (India)

    R K Behera; S P Das

    2008-10-01

    In this paper, a three-level inverter-fed induction motor drive operating under Direct Torque Control (DTC) is presented. A triangular wave is used as dither signal of minute amplitude (for torque hysteresis band and flux hysteresis band respectively) in the error block. This method minimizes flux and torque ripple in a three-level inverter fed induction motor drive while the dynamic performance is not affected. The optimal value of dither frequency and magnitude is found out under free running condition. The proposed technique reduces torque ripple by 60% (peak to peak) compared to the case without dither injection, results in low acoustic noise and increases the switching frequency of the inverter. A laboratory prototype of the drive system has been developed and the simulation and experimental results are reported.

  3. Improved Torque Control Performance in Direct Torque Control using Optimal Switching Vectors

    OpenAIRE

    Muhd Zharif Rifqi Zuber Ahmadi; Auzani Jidin; Maaspaliza Azri; Khairi Rahim; Tole Sutikno

    2015-01-01

    This paper presents the significant improvement of Direct Torque Control (DTC) of 3-phases induction machine using a Cascaded H-Bidge Multilevel Inverter (CHMI). The largest torque ripple and variable switching frequency are known as the major problem founded in DTC of induction motor. As a result, it can diminish the performance induction motor control. Therefore, the conventional 2-level inverter has been replaced with CHMI the in order to increase the performance of the motor either in dyn...

  4. Observerless Scheme for Sensorless Speed Control of PMSM Using Direct Torque Control Method With LP Filter

    OpenAIRE

    BEKIROGLU, N.; OZCIRA, S.

    2010-01-01

    In this study, direct torque control (DTC) of a permanent magnet synchronous motor is realized with a sensorless speed control technique without using an observer. Space vector pulse width modulation (SVPWM) technique is applied in order to determine the switching sequence of the voltage source inverter. Torque and flux, the main variables of the DTC, are estimated by using the mathematical model of the motor. Estimated torque and flux values are compared with their references in every con...

  5. Contouring Control for a CNC Milling Machine Driven by Direct thrust Controlled Linear Induction Motors

    OpenAIRE

    Khaled N. Faris; Hala S. Khalil,; Khaled S. Sakkoury

    2015-01-01

    According to various advantages of linear induction motor (LIM), such as high starting thrust force, high speed operation and reduction of mechanical losses, more applications have utilized this type of motors. Direct Thrust Control (DTC) technique is considered as one of the most efficient techniques that can be used for LIM. DTC is preferable to give a fast and good dynamic thrust response. So, to improve the accuracy and robustness of contouring control for CNC mach...

  6. A High-Performance Motion Control System of Reluctance Synchronous Motor with Direct Torque Control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Huei; Kim, Nam Hun; Choi, Kyeong Ho [Yeungnam University, Kyongsan(Korea)

    2002-03-01

    This paper presents preliminarily an implementation of digital high-performance motion control system of Reluctance Synchronous Motor (RSM) drives with direct torque control(DTC). The system consist of stator flux observer, torque estimator two hysteresis band controllers, an optimal switching look-up table, IGBT voltage source inverter, and TMS320F240 DSP controller made by Texas Instruments. The stator flux observer is based on the combined voltage and current model with stator flux feedback adaptive control, and the input of the observer are the stator voltage and current of motor terminal for wide speed range. The rotor position and speed sensor used 6000 pulse/rev encoder. In order to prove rightness of the suggested control algorithm, we have some simulation and actual experimental system at +-2000 rpm. The developed digitally high performance using 1kW RSM which has 2.57 Ld/Lq salient ratio. (author). 18 refs., 8 figs., 2 tabs.

  7. Structure of controllers for the direct digital control of reactor power

    International Nuclear Information System (INIS)

    The structure of controllers for the direct digital control of power in a nuclear reactor is examined and features possibly important to licensing are identified. This was done by first reviewing the human approach to process control and then discussing designs whereby digital systems could be made to emulate each of the functions that a human operator now performs. Features identified as relevant to licensing include the separation of the safety and control systems, the use of supervisory algorithms that incorporate the concept of feasibility of control, signal validation, verification of signal implementation, and the use of either fault-tolerant or redundant hardware. Examples supporting the above findings are drawn from the MIT experience in first designing and then licensing a digital, closed-loop controller for the 5 MWt MIT Research Reactor

  8. An efficient water flow control approach for water heaters in direct load control

    NARCIS (Netherlands)

    Belov, Alexander; Meratnia, Nirvana; Zwaag, van der Berend Jan; Havinga, Paul

    2014-01-01

    Tank water heaters (WHs) are present in a prevailing number of European households. Serving as energy buffers WHs have come under the spotlight of various direct load control (DLC) programs over the last few decades. Although DLC has proven to be an efficient measure towards daily peak demand shavin

  9. Contouring Control for a CNC Milling Machine Driven by Direct thrust Controlled Linear Induction Motors

    Directory of Open Access Journals (Sweden)

    Khaled N. Faris

    2015-12-01

    Full Text Available According to various advantages of linear induction motor (LIM, such as high starting thrust force, high speed operation and reduction of mechanical losses, more applications have utilized this type of motors. Direct Thrust Control (DTC technique is considered as one of the most efficient techniques that can be used for LIM. DTC is preferable to give a fast and good dynamic thrust response. So, to improve the accuracy and robustness of contouring control for CNC machine tools, linear induction motors with a direct thrust control technique are introduced for driving these machines. An industry standard motion control system is applied for reducing the tracking error and improving the desired accuracy. Different loading conditions are simulated to validate the reliability and robustness of the introduced system to match the application field. The proposed system is simulated using the MATLAB/SIMULINK Package; simulation results validated both tracking accuracy and robustness of the proposed motion control system for contouring control for a CNC (Computer Numerical Control milling machine.

  10. Optimization of a neural network based direct inverse control for controlling a quadrotor unmanned aerial vehicle

    Directory of Open Access Journals (Sweden)

    Heryanto M Ary

    2015-01-01

    Full Text Available UAVs are mostly used for surveillance, inspection and data acquisition. We have developed a Quadrotor UAV that is constructed based on a four motors with a lift-generating propeller at each motors. In this paper, we discuss the development of a quadrotor and its neural networks direct inverse control model using the actual flight data. To obtain a better performance of the control system of the UAV, we proposed an Optimized Direct Inverse controller based on re-training the neural networks with the new data generated from optimal maneuvers of the quadrotor. Through simulation of the quadrotor using the developed DIC and Optimized DIC model, results show that both models have the ability to stabilize the quadrotor with a good tracking performance. The optimized DIC model, however, has shown a better performance, especially in the settling time parameter.

  11. Improved Torque Control Performance of Direct Torque Control for 5-Phase Induction Machine

    Directory of Open Access Journals (Sweden)

    Logan Raj Lourdes Victor Raj

    2013-12-01

    Full Text Available In this paper, the control of five-phase induction machine using Direct Torque Control (DTC is presented. The general D-Q model of five-phase induction machine is discussed. The de-coupled control of stator flux and electromagnetic torque based on hysteresis controller similar to conventional DTC is applied to maintain the simplicity of the system. Three sets of look-up tables consist of voltage vectors with different amplitude that selects the  most optimal voltage vectors according motor operation condition is proposed. This provides excellent torque dynamic control, reduces torque ripple, lower switching frequency (high efficiency and extension of constant torque. Simulation results validate the improvement achieved.

  12. FPGA-Based Implementation Direct Torque Control of Induction Motor

    Directory of Open Access Journals (Sweden)

    Saber Krim

    2015-02-01

    Full Text Available This paper proposes a digital implementation of the direct torque control (DTC of an Induction Motor (IM with an observation strategy on the Field Programmable Gate Array (FPGA. The hardware solution based on the FPGA is caracterised by fast processing speed due to the parallel processing. In this study the FPGA is used to overcome the limitation of the software solutions (Digital Signal Processor (DSP and Microcontroller. Also, the DTC of IM has many drawbacks such as for example; The open loop pure integration has from the problems of integration especially at the low speed and the variation of the stator resistance due to the temperature. To tackle these problems we use the Sliding Mode Observer (SMO. This observer is used estimate the stator flux, the stator current and the stator resistance. The hardware implementation method is based on Xilinx System Generator (XSG which a modeling tool developed by Xilinx for the design of implemented systems on FPGA; from the design of the DTC with SMO from XSG we can automatically generate the VHDL code. The model of the DTC with SMO has been designed and simulated using XSG blocks, synthesized with Xilinx ISE 12.4 tool and implemented on Xilinx Virtex-V FPGA.

  13. A Model of FPGA-based Direct Torque Controller

    Directory of Open Access Journals (Sweden)

    Auzani Jidin

    2013-02-01

    Full Text Available This paper presents a generic model of a fully FPGA-based direct torque controller. This model is developed using two’s-complement fixed-point format approaches, in register-transfer-level (RTL VHDL abstraction for minimizing calculation errors and consuming hardware resource usage. Therefore, the model is universal and can be implemented for all FPGA types. The model is prepared for fast computation, without using of CORDIC algorithm, a soft-core CPU, a transformation from Cartesian-to-polar coordinates, and without the help of third-party applications. To get simpler implementation and fast computation, several methods were introduced: i the backward-Euler approach to calculate the discrete-integration operation of stator flux, ii the modified non-restoring method to calculate complicated square-root operation of stator flux, iii a new sector analysis method. The design, which was coded in synthesizable VHDL in RTL abstraction for implementation on Altera DE2-board has produced very-precise calculations, with minimal error when being compared to MATLAB/Simulink double-precision calculation.

  14. Physical controls on directed virus assembly at nanoscale chemical templates

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, C L; Chung, S; Chatterji, A; Lin, T; Johnson, J E; Hok, S; Perkins, J; De Yoreo, J

    2006-05-10

    Viruses are attractive building blocks for nanoscale heterostructures, but little is understood about the physical principles governing their directed assembly. In-situ force microscopy was used to investigate organization of Cowpea Mosaic Virus engineered to bind specifically and reversibly at nanoscale chemical templates with sub-30nm features. Morphological evolution and assembly kinetics were measured as virus flux and inter-viral potential were varied. The resulting morphologies were similar to those of atomic-scale epitaxial systems, but the underlying thermodynamics was analogous to that of colloidal systems in confined geometries. The 1D templates biased the location of initial cluster formation, introduced asymmetric sticking probabilities, and drove 1D and 2D condensation at subcritical volume fractions. The growth kinetics followed a t{sup 1/2} law controlled by the slow diffusion of viruses. The lateral expansion of virus clusters that initially form on the 1D templates following introduction of polyethylene glycol (PEG) into the solution suggests a significant role for weak interaction.

  15. High Performance Direct Torque Control of Induction Motor Drives Using Space Vector Modulation

    OpenAIRE

    S. Allirani; Jagannathan, V.

    2010-01-01

    This paper presents a simple approach to design and implement Direct Torque Control technique for voltage source inverter fed induction motor drives. The direct torque control is one of the excellent strategies available for torque control of induction machine. It is considered as an alternative to field oriented control technique. The Direct Torque Control scheme is characterized by the absence of PI regulators, co-ordinate transformations, current regulators and pulse width modulated signal...

  16. 47 CFR 90.461 - Direct and remote control of transmitters.

    Science.gov (United States)

    2010-10-01

    ... RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Transmitter Control § 90.461 Direct and remote control of transmitters. (a) In general. Radio transmitters may be operated and controlled directly (as when... are at different locations). (b) Control of transmitters at remote locations. Radio transmitters...

  17. Observerless Scheme for Sensorless Speed Control of PMSM Using Direct Torque Control Method With LP Filter

    Directory of Open Access Journals (Sweden)

    BEKIROGLU, N.

    2010-08-01

    Full Text Available In this study, direct torque control (DTC of a permanent magnet synchronous motor is realized with a sensorless speed control technique without using an observer. Space vector pulse width modulation (SVPWM technique is applied in order to determine the switching sequence of the voltage source inverter. Torque and flux, the main variables of the DTC, are estimated by using the mathematical model of the motor. Estimated torque and flux values are compared with their references in every control cycle. Then, according to the torque and flux demand, the voltage vector is constituted. In the proposed control scheme, speed is estimated by using flux calculations and a PI controller is used to process the torque and flux errors. Furthermore, a low-pass (LP filter is implemented within the proposed system for voltage and current harmonics suppression. The results proved that proposed scheme for the DTC provides the speed control under various torque demands without employing a sensor. The proposed system performs very well for a sensorless operation and effectively eliminates the harmonics due to the LP filter.

  18. A High-Performance Position Sensorless Motion Control system of Induction Motor with Direct Torque Control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Huei; Kim, Nam Hun; Baik, Won sik [Yeungnam University, Kyongsan (Korea)

    2002-07-01

    This paper presents an implementation of digital high-performance position sensorless motion control system of and induction motor drives with Direct Torque Control(DTC). The system consist of closed loop stator flux and torque observer, speed and torque estimators, two hysteresis controller, optimal switching look-up table, IGBT voltage source inverter, and TMS320C31 DSP board. The stator flux observer is based on the combined current and voltage model with stator flux feedback adaptive control of which inputs are current and voltage sensed on motor terminal for wide speed range. The speed observer is using the model reference adaptive system(MRAS) with rotor flux linkages for speed turning signal. The simulation and experimental results are provided to evaluate the consistency and the performance of the suggested position sensorless control algorithm. The developed position sensorless system are shown are show a good motion control response characteristic and high performance features using 2.2(kW) general purposed induction motor . (author). 12 refs., 7 figs., 1 tab.

  19. Direct Control Implementation of a Refrigeration System in Smart Grid

    DEFF Research Database (Denmark)

    Pedersen, Rasmus; Schwensen, John; Sivabalan, Senthuran;

    2013-01-01

    controlled smart grid, by use of a predictive control strategy. In this application the shift in consumption is used to stabilize a small grid by utilizing excess renewable energy to minimize the need for fossil fueled production sources. In order for the centralized grid controller to handle such a node...

  20. 75 FR 80066 - Quality Control Requirements for Direct Endorsement Lenders; Notice of Proposed Information...

    Science.gov (United States)

    2010-12-21

    ... URBAN DEVELOPMENT Quality Control Requirements for Direct Endorsement Lenders; Notice of Proposed.... This Notice also lists the following information: Title of Proposal: Quality Control Requirements for... lenders, since these institutions must also conduct quality control on all loans they originate...

  1. Direction-Dependent Control of Balance During Walking and Standing

    OpenAIRE

    O'Connor, Shawn M.; Kuo, Arthur D.

    2009-01-01

    Human walking has previously been described as “controlled falling.” Some computational models, however, suggest that gait may also have self-stabilizing aspects requiring little CNS control. The fore–aft component of walking may even be passively stable from step to step, whereas lateral motion may be unstable and require motor control for balance, as through active foot placement. If this is the case, walking humans might rely less on integrative sensory feedback, such as vision, for antero...

  2. Direct digital control of the WWR-SM research reactor

    International Nuclear Information System (INIS)

    The report describes the computerized control system of a 5 MW WWR-SM research reactor. The system is realized as a multilayer decision hierarchy where simple subsystems control the power and the outlet temperature of the reactor under the supervision of a self-organization layer. The structure of the program system and the hardware configuration are presented. (author)

  3. Post-directed weed control in bell peppers

    Science.gov (United States)

    Organic pepper (Capsicum annuum L.) producers need appropriate herbicides that can effectively provide post-emergent weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of a potential organic herbicide on weed control efficacy, crop injury, an...

  4. Improved Torque Control Performance in Direct Torque Control using Optimal Switching Vectors

    Directory of Open Access Journals (Sweden)

    Muhd Zharif Rifqi Zuber Ahmadi

    2015-02-01

    Full Text Available This paper presents the significant improvement of Direct Torque Control (DTC of 3-phases induction machine using a Cascaded H-Bidge Multilevel Inverter (CHMI. The largest torque ripple and variable switching frequency are known as the major problem founded in DTC of induction motor. As a result, it can diminish the performance induction motor control. Therefore, the conventional 2-level inverter has been replaced with CHMI the in order to increase the performance of the motor either in dynamic or steady-state condition. By using the multilevel inverter, it can produce a more selection of the voltage vectors. Besides that, it can minimize the torque ripple output as well as increase the efficiency by reducing the switching frequency of the inverter. The simulation model of the proposed method has been developed and tested by using Matlab software. Its improvements were also verified via experimental results.

  5. Directional Medium Access Control (MAC Protocols in Wireless Ad Hoc and Sensor Networks: A Survey

    Directory of Open Access Journals (Sweden)

    David Tung Chong Wong

    2015-06-01

    Full Text Available This survey paper presents the state-of-the-art directional medium access control (MAC protocols in wireless ad hoc and sensor networks (WAHSNs. The key benefits of directional antennas over omni-directional antennas are longer communication range, less multipath interference, more spatial reuse, more secure communications, higher throughput and reduced latency. However, directional antennas lead to single-/multi-channel directional hidden/exposed terminals, deafness and neighborhood, head-of-line blocking, and MAC-layer capture which need to be overcome. Addressing these problems and benefits for directional antennas to MAC protocols leads to many classes of directional MAC protocols in WAHSNs. These classes of directional MAC protocols presented in this survey paper include single-channel, multi-channel, cooperative and cognitive directional MACs. Single-channel directional MAC protocols can be classified as contention-based or non-contention-based or hybrid-based, while multi-channel directional MAC protocols commonly use a common control channel for control packets/tones and one or more data channels for directional data transmissions. Cooperative directional MAC protocols improve throughput in WAHSNs via directional multi-rate/single-relay/multiple-relay/two frequency channels/polarization, while cognitive directional MAC protocols leverage on conventional directional MAC protocols with new twists to address dynamic spectrum access. All of these directional MAC protocols are the pillars for the design of future directional MAC protocols in WAHSNs.

  6. High Performance Direct Torque Control of Induction Motor Drives Using Space Vector Modulation

    Directory of Open Access Journals (Sweden)

    S. Allirani

    2010-11-01

    Full Text Available This paper presents a simple approach to design and implement Direct Torque Control technique for voltage source inverter fed induction motor drives. The direct torque control is one of the excellent strategies available for torque control of induction machine. It is considered as an alternative to field oriented control technique. The Direct Torque Control scheme is characterized by the absence of PI regulators, co-ordinate transformations, current regulators and pulse width modulated signal generators. Direct Torque Control allows a good torque control in steady state and transient operating conditions. The direct torque control technique based on space vector modulation and switching table has been developed and presented in this paper.

  7. QuickDirect - Payload Control Software Template Package Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the need to quickly, cost-effectively and reliably develop software to control science instruments deployed on spacecraft, QuickFlex proposes to create a...

  8. Direct Torque Control Induction Motor Drive with Improved Flux Response

    OpenAIRE

    Bhoopendra Singh; Shailendra Jain; Sanjeet Dwivedi

    2012-01-01

    Accurate flux estimation and control of stator flux by the flux control loop is the determining factor in effective implementation of DTC algorithm. In this paper a comparison of voltage-model-based flux estimation techniques for flux response improvement is carried out. The effectiveness of these methods is judged on the basis of Root Mean Square Flux Error (RMSFE), Total Harmonic Distortion (THD) of stator current, and dynamic flux response. The theoretical aspects of these methods are disc...

  9. A direct computer control concept for mammalian cell fermentation processes

    OpenAIRE

    Büntemeyer, Heino; Marzahl, Rainer; Lehmann, Jürgen

    1994-01-01

    In the last 10 years, new assignments and the special demands of mammalian cells to the culture conditions caused the development of complex small scale fermentation setups. The use of continuous fermentation and cell retention devices requires appropriate process control systems. An arrangement for control and data-acquisition of complex laboratory-scale bioreactors is presented. The fundamental idea was the usage of a standard personal computer, which is connected to pumps, valves and senso...

  10. How do emotion and motivation direct executive control?

    OpenAIRE

    Pessoa, Luiz

    2009-01-01

    Emotion and motivation have crucial roles in determining human behavior. Yet, how they interact with cognitive control functions is less understood. Here, the basic elements of a conceptual framework for understanding how they interact are introduced. More broadly, the `dual competition' framework proposes that emotion and motivation affect both perceptual and executive competition. In particular, the anterior cingulate cortex is hypothesized to be engaged in attentional/effortful control mec...

  11. A Direct Power Controlled and Series Compensated EHV Transmission Line

    OpenAIRE

    Dodson, Andrew; McCann, Roy

    2013-01-01

    This paper presents the design and analysis of a compensation method with application to a 345 kV 480 MVA three-phase transmission line. The compensator system includes a series injected voltage source converter that minimizes the resonance effects of capacitor line reactance. This creates an ability to compensate for the effects of subsynchronous resonance and thereby increase line loadability and control real and reactive power flows. The granularity of power flow control and simultaneous s...

  12. Fuzzy Logic Based Direct Torque Control Of Induction Motor With Space Vector Modulation

    OpenAIRE

    Korkmaz, Fatih; TOPALOĞLU, İsmail; Mamur, Hayati

    2015-01-01

    The induction motors have wide range of applications for due to its well-known advantages like brushless structures, low costs and robust performances. Over the past years, many kind of control methods are proposed for the induction motors and direct torque control has gained huge importance inside of them due to fast dynamic torque responses and simple control structures. However, the direct torque control method has still some handicaps against the other control methods and most of the impo...

  13. Direction-Specific Interactions Control Crystal Growth by Oriented Attachment

    Science.gov (United States)

    Li, Dongsheng; Nielsen, Michael H.; Lee, Jonathan R. I.; Frandsen, Cathrine; Banfield, Jillian F.; De Yoreo, James J.

    2012-05-01

    The oriented attachment of molecular clusters and nanoparticles in solution is now recognized as an important mechanism of crystal growth in many materials, yet the alignment process and attachment mechanism have not been established. We performed high-resolution transmission electron microscopy using a fluid cell to directly observe oriented attachment of iron oxyhydroxide nanoparticles. The particles undergo continuous rotation and interaction until they find a perfect lattice match. A sudden jump to contact then occurs over less than 1 nanometer, followed by lateral atom-by-atom addition initiated at the contact point. Interface elimination proceeds at a rate consistent with the curvature dependence of the Gibbs free energy. Measured translational and rotational accelerations show that strong, highly direction-specific interactions drive crystal growth via oriented attachment.

  14. Flow and Noise Control: Review and Assessment of Future Directions

    Science.gov (United States)

    Thomas, Russell H.; Choudhari, Meelan M.; Joslin, Ronald D.

    2002-01-01

    Technologies for developing radically new aerovehicles that would combine quantum leaps in cost, safety, and performance benefits with environmental friendliness have appeared on the horizon. This report provides both an assessment of the current state-of-the-art in flow and noise control and a vision for the potential gains to be made, in terms of performance benefit for civil and military aircraft and a unique potential for noise reduction, via future advances in flow and noise technologies. This report outlines specific areas of research that will enable the breakthroughs necessary to bring this vision to reality. Recent developments in many topics within flow and noise control are reviewed. The flow control overview provides succinct summaries of various approaches for drag reduction and improved maneuvering. Both exterior and interior noise problems are examined, including dominant noise sources, physics of noise generation and propagation, and both established and proposed concepts for noise reduction. Synergy between flow and noise control is a focus and, more broadly, the need to pursue research in a more concurrent approach involving multiple disciplines. Also discussed are emerging technologies such as nanotechnology that may have a significant impact on the progress of flow and noise control.

  15. High efficiency direct energy conversion in controlled thermonuclear fusion reactors

    International Nuclear Information System (INIS)

    Still many physical and engineering subjects must be overcome before the realization of commercial nuclear fusion reactors. But if its realization is aimed at in the middle period of 21st century, the competition with other energy sources, particularly advanced nuclear fission reactors, is the problem. In order that nuclear fusion reactors are accepted by the society, it is indispensable to verify their superiority in the fields of the safety, reliability and economical efficiency. As one of their many potential superiority, there is the high efficiency direct electric power generation related to nuclear fusion reactors. In principle, this is to convert the kinetic energy that plasma and ion beam possess directly to electric energy through electromagnetic fields, and high efficiency that largely surpasses that by conventional steam power generation is obtainable. In this report, as the methods of representative direct energy conversion, electrostatic energy conversion, energy conversion by electromagnetic waves and inductive energy conversion are explained by showing the concrete examples. (K.I.)

  16. Average Consensus Problems in Networks of Agents with Fixed and Switching Topology and Unknown Control Direction

    Directory of Open Access Journals (Sweden)

    Caixian Sun

    2014-01-01

    Full Text Available This paper is devoted to the average consensus problems in directed networks of agents with unknown control direction. In this paper, by using Nussbaum function techniques and Laplacian matrix, novel average consensus protocols are designed for multiagent systems with unknown control direction in the cases of directed networks with fixed and switching topology. In the case of switching topology, the disagreement vector is utilized. Finally, simulation is provided to demonstrate the effectiveness of our results.

  17. Reaction Force Control of a Linear Electrical Generator for Direct Drive Wave Energy Conversion

    OpenAIRE

    Shek, J.K.H.; Macpherson, D.E.; Mueller, M.A.; Xiang, J.

    2007-01-01

    Direct drive wave energy converters have been proposed in view of the disadvantage of mechanical complexity and low conversion efficiencies in conventional wave energy converters. By directly coupling a linear generator to a reciprocating wave energy device, it is suggested that direct drive power take-off could be a viable alternative to hydraulic- and pneumatic-based systems. To further realise the benefits of a direct drive system, a control scheme based on reaction force control to maximi...

  18. Effects of Edge Directions on the Structural Controllability of Complex Networks

    OpenAIRE

    Xiao, Yandong; Lao, Songyang; Hou, Lvlin; Small, Michael; Bai, Liang

    2015-01-01

    Recent advances indicate that assigning or reversing edge direction can significantly improve the structural controllability of complex networks. For directed networks, approaching the optimal structural controllability can be achieved by detecting and reversing certain “inappropriate” edge directions. However, the existence of multiple sets of “inappropriate” edge directions suggests that different edges have different effects on optimal controllability—that is, different combinations of edg...

  19. Direct Torque Control Induction Motor Drive with Improved Flux Response

    Directory of Open Access Journals (Sweden)

    Bhoopendra Singh

    2012-01-01

    Full Text Available Accurate flux estimation and control of stator flux by the flux control loop is the determining factor in effective implementation of DTC algorithm. In this paper a comparison of voltage-model-based flux estimation techniques for flux response improvement is carried out. The effectiveness of these methods is judged on the basis of Root Mean Square Flux Error (RMSFE, Total Harmonic Distortion (THD of stator current, and dynamic flux response. The theoretical aspects of these methods are discussed and a comparative analysis is provided with emphasis on digital signal processor (DSP based controller implementation. The effectiveness of the proposed flux estimation algorithm is investigated through simulation and experimentally validated on a test drive.

  20. System for direct control of haulage speed of shearer loaders

    Energy Technology Data Exchange (ETDEWEB)

    Podsiadlo, A. (Akademia Gorniczo-Hutnicza, Cracow (Poland). Instytut Maszyn Gorniczych, Przerobczych i Automatyki Gorniczej)

    1989-10-01

    Evaluates design and operation of an experimental unit of a microprocessor system for control of drives for cutting heads of the KGS 320 shearer loader, tested in the Jankowice mine. A prototype of the system was developed. The following elements of the system are evaluated: a converter of current driving cutting head motors, a pressure converter in the main circuit of hydrostatic converter, a converter measuring shearer loader speed, a control system for shearer loader speed, regulators, a system for operation of the Herion HDSV 2A servovalve. 1 ref.

  1. Application of Space Vector Modulation in Direct Torque Control of PMSM

    Directory of Open Access Journals (Sweden)

    Michal Malek

    2008-01-01

    Full Text Available The paper deals with an improvement of direct torque control method for permanent magnet synchronous motor drives. Electrical torque distortion of the machine under original direct torque control is relatively high and if proper measures are taken it can be substantially decreased. The proposed solution here is to combine direct torque control with the space vector modulation technique. Such approach can eliminate torque distortion while preserving the simplicity of the original method.

  2. Application of space vector modulation in direct torque control of PMSM

    OpenAIRE

    Michal Malek; Jan Vittek; Vladimir Vavrus; Marek Stulrajter

    2008-01-01

    The paper deals with an improvement of direct torque control method for permanent magnet synchronous motor drives. Electrical torque distortion of the machine under original direct torque control is relatively high and if proper measures are taken it can be substantially decreased. The proposed solution here is to combine direct torque control with the space vector modulation technique. Such approach can eliminate torque distortion while preserving the simplicity of the original method.

  3. Controlled Directional Growth of TiO2 Nanotubes

    DEFF Research Database (Denmark)

    In, Su-il; Hou, Yidong; Abrams, Billie; Vesborg, Peter Christian Kjærgaard; Chorkendorff, Ib

    2010-01-01

    substrates in a single step. By controlling the oxygen concentration, the electrical contact to the titanium film can be preserved until the entire film is anodized. This approach to growing transparent TiO2 NT films yields possibilities for using glass without any transparent conducting oxide coating as...

  4. System for controllable magnetic measurement with direct field determination

    Czech Academy of Sciences Publication Activity Database

    Stupakov, Oleksandr

    2012-01-01

    Roč. 324, č. 4 (2012), 631-636. ISSN 0304-8853 R&D Projects: GA ČR GP102/09/P108 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic measurement * surface field measurement * induction waveform control * electrical steel Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012

  5. Considerations about direct torque control and encoder-less operation of induction motor drives

    Directory of Open Access Journals (Sweden)

    Dragos Cristian Spoiala

    2009-10-01

    Full Text Available The paper presents the principle of direct torque control and encoder-less operation of the induction machines. Direct Torque Control - or DTC - is the most advanced AC drive technology developed by any manufacturer in the world. Comparative to vectorcontrol, direct torque control (DTC techniques need no axis transformation and the electromagnetic torque and the stator flux are estimated and directly controlled by applying the appropriate stator voltage vector. Aditionally, it is possible to estimate the rotor speed without the use of an encoder.

  6. Active control of emission directionality of semiconductor microdisk lasers

    CERN Document Server

    Liew, Seng Fatt; Ge, Li; Solomon, Glenn S; Cao, Hui

    2014-01-01

    We demonstrate lasing mode selection in nearly circular semiconductor microdisks by shaping the spatial profile of optical pump. Despite of strong mode overlap, adaptive pumping suppresses all lasing modes except the targeted one. Due to slight deformation of the cavity shape and boundary roughness, each lasing mode has distinct emission pattern. By selecting different mode to be the dominant lasing mode, we can switch both the lasing frequency and the output direction. Such tunability by external pump after the laser is fabricated enhances the functionality of semiconductor microcavity lasers.

  7. DEVELOPMENT OF DIRECT TORQUE CONTROL MODELWITH USING SVI FOR THREE PHASE INDUCTION MOTOR

    Directory of Open Access Journals (Sweden)

    MUKESH KUMAR ARYA

    2011-08-01

    Full Text Available Direct torque control method is one of the best control strategies which allow a torque control in steady state and transient operation of induction motor. The main aim of direct torque control strategies is to effectively control the torque and flux of induction motor. Direct torque control method made the motor more accurate and fasttorque control, high dynamic speed response and simple to control. This paper present the principle of the direct torque control for voltage source inverter fed induction motor drive, and switching table, amplitude selection of the hysterics band of torque and flux. and also this method based on space vector modulation And its considered as an alternative to field oriented control technique. direct torque control methods is the first technology to control the ‘real’ motor control variable of torque and flux. and its has also more advantage such as it not required a feedback device and also not need external excitation. The performance of direct torque controlmethod has been demonstrated by simulation using a simulation package in matlab.

  8. Research on Direct Torque Control of Induction Motor Based on TMS320LF2407A

    Science.gov (United States)

    Lufei, Xu; Guangqun, Nan

    The direct torque control of Induction Motor is one of the high performance control system, which was proposed after the vector control scheme. During the recent 20 years, It has been developed rapidly for its concise system scheme, excellent dynamic and static performances. DTC system directly controls the electromagnetic torque and stator flux, using the analyzing method of space vector and stator flux orientation. This paper establishes the mathematical model of direct torque control (DTC) system of induction motor, and direct torque control (DTC) scheme of induction motor based on TMS320LF2407A is introduced. The control scheme gets the switch control signal of inverter with the space voltage vector modulation technology. Finally the approach has been implemented on DSP in a 1.1 kW drive. The results show that the DTC with SVPWM has many merits such as simple realization, good running performance and high voltage utilization ratio.

  9. Simulation of Brushless DC Motor using Direct Torque Control

    OpenAIRE

    Mrs.G. Kusuma; S. Rukhsana Begum

    2014-01-01

    This paper deals with modelling of three phases brushless dc motor with MATLAB/SIMULINK software BLDC motor have advantages according to brushless dc motor and induction motor’s. They have improve speed torque charactistics, high efficiency high transient response and small size. It approaches for reducing the torque ripples of BLDC motor using DTC, by using control technique’s ,but present work mainly concentrate on advanced method. The whole drive system is simulated based o...

  10. Nonlinear Observer Based Sensorless Direct Torque Control of Induction Motor

    OpenAIRE

    Pai, Dinesh A; Mangsuli, Purnaprajna R; Rao, NJ

    2000-01-01

    Induction motor speed control is an area of research that has been in prominence for some time now. Recent advances in this field have made it possible to replace the DC motor by induction machines, even in applications that demand a fast dynamic response. Many industrial applications demand speed sensorless operations, due to various reasons. It is also required to strictly maintain the speed of the motor within certain permissible tolerance, irrespective of the load changes that occur in th...

  11. Power Balancing Aggregator Design for Industrial Consumers Using Direct Control

    OpenAIRE

    Rahnama, Samira; Bendtsen, Jan Dimon; Stoustrup, Jakob; Rasmussen, Henrik

    2015-01-01

    Demand side management in the future smart grid requires new players in the electricity markets. We assume a player, the so-called aggregator which aims to utilize the flexibility in large-scale consumers with thermal energy storage. An aggregator design is proposed to mange the power consumption of flexible demands during a certain period of time. The setup consists of an MPC-like controller to optimally operate the consumption units for upward and downward regulating power provision. To han...

  12. The Dual Control Model: current status and future directions

    OpenAIRE

    Bancroft, John; Graham, Cynthia A.; Janssen, Erick; Sanders, Stephanie

    2009-01-01

    The Dual Control Model proposes that sexual responses involve an interaction between sexual excitatory and sexual inhibitory processes. The model further postulates that individuals vary in their propensity for both sexual excitation and sexual inhibition, and that such variations help us to understand much of the variability in human sexuality. The development of psychometrically validated instruments for measuring such propensities for men (Sexual Inhibition/Sexual Excitation Scales) and fo...

  13. Effects of Edge Directions on the Structural Controllability of Complex Networks.

    Directory of Open Access Journals (Sweden)

    Yandong Xiao

    Full Text Available Recent advances indicate that assigning or reversing edge direction can significantly improve the structural controllability of complex networks. For directed networks, approaching the optimal structural controllability can be achieved by detecting and reversing certain "inappropriate" edge directions. However, the existence of multiple sets of "inappropriate" edge directions suggests that different edges have different effects on optimal controllability-that is, different combinations of edges can be reversed to achieve the same structural controllability. Therefore, we classify edges into three categories based on their direction: critical, redundant and intermittent. We then investigate the effects of changing these edge directions on network controllability, and demonstrate that the existence of more critical edge directions implies not only a lower cost of modifying inappropriate edges but also better controllability. Motivated by this finding, we present a simple edge orientation method aimed at producing more critical edge directions-utilizing only local information-which achieves near optimal controllability. Furthermore, we explore the effects of edge direction on the controllability of several real networks.

  14. Simulation of Brushless DC Motor using Direct Torque Control

    Directory of Open Access Journals (Sweden)

    Mrs.G. Kusuma

    2014-04-01

    Full Text Available This paper deals with modelling of three phases brushless dc motor with MATLAB/SIMULINK software BLDC motor have advantages according to brushless dc motor and induction motor’s. They have improve speed torque charactistics, high efficiency high transient response and small size. It approaches for reducing the torque ripples of BLDC motor using DTC, by using control technique’s ,but present work mainly concentrate on advanced method. The whole drive system is simulated based on the system devices, BLDC motor source inverter, space vector modulation.

  15. Semiconductor Light-Controlled Instrument Transducer with Direct PWM Output for Automatic Control Systems

    Directory of Open Access Journals (Sweden)

    F. J. De la Hidalga-W

    2013-01-01

    Full Text Available This work shows that the direct PWM output electric signal, with a duty cycle controlled by light intensity, can beobtained using a circuit containing a saw-tooth voltage generator connected in series with a dc voltage source and ametal (semitransparent gate oxide semiconductor capacitor (MOS-C.The internal PWM signal conversion occurs by the use of non-equilibrium physical processes in the semiconductorsubstrate of the MOS-C. The 10-20 V amplitude limited square PWM output signal is obtained by the amplification ofthe sensor signal with a standard 60 dB transimpedance amplifier. The amplified output signal presents positive andnegative PWM waveforms that can be easily separated using diodes. The duty of the positive part is proportional tothe light intensity, whereas the negative part is inversely proportional to the intensity. The frequency operating rangeof this proposed instrument varies from 1 Hz to a few kilohertz. The duty cycle of the PWM output signal varies from2% to 98% when the incident light intensity varies in the microwatts range. These new transducers or sensors couldbe useful for automatic control, robotic applications, dimmer systems, feedback electronic systems, and non-contactoptical position sensing for nulling and centering measurements.

  16. European directive on integrated pollution prevention and control (IPPC) for the large combustion plants

    International Nuclear Information System (INIS)

    The European Directive on Integrated Pollution Prevention and Control (IPPC-Directive) was adopted by the Council in 1966 and lays down a framework within which Member State and local authorities issue operating permits. The purpose of this Directive is to secure a high level of protection for the environmental as a whole at specified industrial installations by using best available techniques (BAT). (Author)

  17. Three-Level Direct Torque Control Based on Artificial Neural Network of Double Star Synchronous Machine

    Directory of Open Access Journals (Sweden)

    Elakhdar BENYOUSSEF

    2014-02-01

    Full Text Available This paper presents a direct torque control strategy for double star synchronous machine fed by two three-level inverters. The analysis of the torque and the stator flux linkage reference frame shows that the concept of direct torque control can be extended easily to double star synchronous machine. The proposed approach consists to replace the switching tables by one artificial neural networks controller. The output switching states vectors of the artificial neural networks controller are used to control the two three-level inverters. Simulations results are given to show the effectiveness and the robustness of the suggested control method.

  18. A performance comparison of DFIG using power transfer matrix and direct power control techniques

    Directory of Open Access Journals (Sweden)

    K. Viswanadha S Murthy

    2014-10-01

    Full Text Available This paper presents a direct power control and power transfer matrix model for a doubly-fed induction generator (DFIG wind energy system (WES. Control of DFIG wind turbine system is traditionally based on either stator-flux-oriented or stator-voltage-oriented vector control. The performance of Direct Power Control (DPC and Power transfer Matrix control for the same wind speed are studied. The Power transfer matrix Control gave better results. The validity and performance of the proposed modelling and control approaches are investigated using a study system consisting of a grid connected DFIG WES. The performance of DFIG with Power Transfer Matrix and Direct Power Control (DPC techniques are obtained through simulation. The time domain simulation of the study system using MATLAB Simulink is carried out. The results obtained in the two cases are compared

  19. Neuromodulatory control of a goal-directed decision.

    Science.gov (United States)

    Hirayama, Keiko; Moroz, Leonid L; Hatcher, Nathan G; Gillette, Rhanor

    2014-01-01

    Many cost-benefit decisions reduce to simple choices between approach or avoidance (or active disregard) to salient stimuli. Physiologically, critical factors in such decisions are modulators of the homeostatic neural networks that bias decision processes from moment to moment. For the predatory sea-slug Pleurobranchaea, serotonin (5-HT) is an intrinsic modulatory promoter of general arousal and feeding. We correlated 5-HT actions on appetitive state with its effects on the approach-avoidance decision in Pleurobranchaea. 5-HT and its precursor 5-hydroxytryptophan (5-HTP) augmented general arousal state and reduced feeding thresholds in intact animals. Moreover, 5-HT switched the turn response to chemosensory stimulation from avoidance to orienting in many animals. In isolated CNSs, bath application of 5-HT both stimulated activity in the feeding motor network and switched the fictive turn response to unilateral sensory nerve stimulation from avoidance to orienting. Previously, it was shown that increasing excitation state of the feeding network reversibly switched the turn motor network response from avoidance to orienting, and that 5-HT levels vary inversely with nutritional state. A simple model posits a critical role for 5-HT in control of the turn network response by corollary output of the feeding network. In it, 5-HT acts as an intrinsic neuromodulatory factor coupled to nutritional status and regulates approach-avoidance via the excitation state of the feeding network. Thus, the neuromodulator is a key organizing element in behavioral choice of approach or avoidance through its actions in promoting appetitive state, in large part via the homeostatic feeding network. PMID:25048964

  20. An Optimal Control Method for Maximizing the Efficiency of Direct Drive Ocean Wave Energy Extraction System

    OpenAIRE

    Chen, Zhongxian; Yu, Haitao; Wen, Cheng

    2014-01-01

    The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the...

  1. New concept of direct torque neuro-fuzzy control for induction motor drives. Simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Grabowski, P.Z. [Institute of Control and Industrial Electronics, Warsaw University of Technology, Warsaw (Poland)

    1997-12-31

    This paper presents a new control strategy in the discrete Direct Torque Control (DTC) based on neuro-fuzzy structure. Two schemes are proposed: neuro-fuzzy switching times calculator and neuro-fuzzy incremental controller with space vector modulator. These control strategies guarantee very good dynamic and steady-states characteristics, with very low sampling time and constant switching frequency. The proposed techniques are verified by simulation study of the whole drive system and results are compared with conventional discrete Direct Torque Control method. (orig.) 18 refs.

  2. Solid state circuit controls direction, speed, and braking of dc motor

    Science.gov (United States)

    Hanna, M. F.

    1966-01-01

    Full-wave bridge rectifier circuit controls the direction, speed, and braking of a dc motor. Gating in the circuit of Silicon Controlled Rectifiers /SCRS/ controls output polarity and braking is provided by an SCR that is gated to short circuit the reverse voltage generated by reversal of motor rotation.

  3. Input-constrained model predictive control via the alternating direction method of multipliers

    DEFF Research Database (Denmark)

    Sokoler, Leo Emil; Frison, Gianluca; Andersen, Martin S.;

    2014-01-01

    This paper presents an algorithm, based on the alternating direction method of multipliers, for the convex optimal control problem arising in input-constrained model predictive control. We develop an efficient implementation of the algorithm for the extended linear quadratic control problem (LQCP...... in computation time grows with the problem size. We improve the method further using a warm-start procedure....

  4. Input-constrained model predictive control via the alternating direction method of multipliers

    DEFF Research Database (Denmark)

    Sokoler, Leo Emil; Frison, Gianluca; Andersen, Martin S.; Jørgensen, John Bagterp

    This paper presents an algorithm, based on the alternating direction method of multipliers, for the convex optimal control problem arising in input-constrained model predictive control. We develop an efficient implementation of the algorithm for the extended linear quadratic control problem (LQCP...

  5. The efficiency of direct torque control for electric vehicle behavior improvement

    Directory of Open Access Journals (Sweden)

    Gasbaoui Brahim

    2011-01-01

    Full Text Available Nowadays the electric vehicle motorization control takes a great interest of industrials for commercialized electric vehicles. This paper is one example of the proposed control methods that ensure both safety and stability the electric vehicle by the means of Direct Torque Control (DTC. For motion of the vehicle the electric drive consists of four wheels: two front ones for steering and two rear ones for propulsion equipped with two induction motors, due to their lightweight simplicity and high performance. Acceleration and steering are ensured by the electronic differential, permitting safe and reliable steering at any curve. The direct torque control ensures efficiently controlled vehicle. Electric vehicle direct torque control is simulated in MATLAB SIMULINK environment. Electric vehicle (EV demonstrated satisfactory results in all type of roads constraints: straight, ramp, downhill and bends.

  6. A NEW FUZZY LOGIC BASED SPACE VECTOR MODULATION APPROACH ON DIRECT TORQUE CONTROLLED INDUCTION MOTORS

    Directory of Open Access Journals (Sweden)

    Fatih Korkmaz

    2013-11-01

    Full Text Available The induction motors are indispensable motor types for industrial applications due to its wellknown advantages. Therefore, many kind of control scheme are proposed for induction motors over the past years and direct torque control has gained great importance inside of them due to fast dynamic torque response behavior and simple control structure. This paper suggests a new approach on the direct torque controlled induction motors, Fuzzy logic based space vector modulation, to overcome disadvantages of conventional direct torque control like high torque ripple. In the proposed approach, optimum switching states are calculated by fuzzy logic controller and applied by space vector pulse width modulator to voltage source inverter. In order to test and compare the proposed DTC scheme with conventional DTC scheme simulations, in Matlab/Simulink, have been carried out in different speed and load conditions. The simulation results showed that a significant improvement in the dynamic torque and speed responses when compared to the conventional DTC scheme.

  7. Analysis and control of excitation, field weakening and stability in direct torque controlled electrically excited synchronous motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Pyrhoenen, O.

    1998-01-01

    Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor's electromagnetic state and load. The load angle can be limited indirectly by limiting the

  8. Analysis and control of excitation, field weakening and stability in direct torque controlled electrically excited synchronous motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Pyrhoenen, O.

    1998-12-31

    Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor`s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque

  9. Velocity Control for Coning Motion Missile System Using Direct Discretization Method

    OpenAIRE

    Rui-sheng Sun; Chao Ming

    2015-01-01

    This paper presents a new coning motion control methodology, which takes into account the terminal speed constraint to design the velocity control system for a missile. By using a direct discretization method to transform the optimal control problem into a nonlinear dynamic programming problem, the optimal trajectory and velocity profile are obtained to satisfy the design index requirement. In order to perform the velocity control, a virtual moving target is proposed for the missile to chase ...

  10. Variable-Structure Direct Torque Control – A Class of Fast and Robust Controllers for Induction Machine Drives

    DEFF Research Database (Denmark)

    Lascu, Christian; Boldea, Ion; Blaabjerg, Frede

    2004-01-01

    A family of variable-structure controllers for induction machine drives is presented, in which the principles of direct torque control (DTC), variable-structure control (VSC) and space-vector pulsewidth modulation are combined to ensure high-performance operation, both in the steady state and under...... transient conditions. Three new VSC schemes are designed following the DTC voltage-control-based philosophy. These provide robust, fast and accurate torque and flux control, without the penalty of high chattering. Comparative results demonstrate that proposed techniques preserve the DTC transient merits...

  11. Direct Torque Control in presence of Current sensor failure in Variable Speed Wind System: Effect analysis, detection and control reconfiguration

    Directory of Open Access Journals (Sweden)

    A. J. Arbi

    2008-03-01

    Full Text Available This paper presents a study of current sensor failure in a Direct Torque Control applied to a Double Fed Induction Generator based Variable Speed Wind System. The effect of scaling and offset current sensor errors is discussed through sensibility analysis. A control reconfiguration is then proposed to remedy this sensor failure. Simulation results emphasize the good performances of the proposed current sensor fault tolerant control

  12. Experimental direct digital control of the power plant A1 reactor based on a modern control theory approach

    International Nuclear Information System (INIS)

    The objective of the project was to accumulate technical experience with application of modern control theory in nuclear power by carrying out a case study of an experimental direct digital control at the A1 reactor about its nominal steady state. The research has proved that slightly modified method of solution of the linear stochastic regulator problem can be successfully applied in design of digital control system of nuclear power reactors

  13. Minimization of torque ripple in switched reluctance motor drives using direct instantaneous torque control

    OpenAIRE

    Castro Soriano, Javier; Andrada Gascón, Pedro; Blanqué Molina, Balduino

    2012-01-01

    Torque ripple is an inherent characteristic of switched reluctance motor drives due to its double salient geometry and it is a serious drawback in applications that require smooth torque and high dynamic performances. This paper presents some contributions to the minimization of torque ripple in SRM using direct instantaneous torque control (DITC). Direct torque controller is simulated using Matlab/Simulink and then implemented in a DSPACE ACE kit 1006 CLP that includes a processor boar...

  14. Multimodel Modeling and Predictive Control for Direct-Drive Wind Turbine with Permanent Magnet Synchronous Generator

    OpenAIRE

    Lei Wang; Tao Shen; Chen Chen

    2014-01-01

    The safety and reliability of the wind turbines wholly depend on the completeness and reliability of the control system which is an important problem for the validity of the wind energy conversion systems (WECSs). A method based on multimodel modeling and predictive control is proposed for the optimal operation of direct-drive wind turbine with permanent magnet synchronous generator in this paper. In this strategy, wind turbine with direct-drive permanent magnet synchronous generator is model...

  15. Frequency Properties Research of Elevator Drive System with Direct Torque Control-Pulse with Modulation

    Directory of Open Access Journals (Sweden)

    A. S. Koval

    2008-01-01

    Full Text Available In the article problems of frequency properties research for electric drive system with direct torque control and pulse width modulator are described. The mathematical description of elevator is present. Simplified mathematical description of direct torque control - pulse width modulator electric drive system is shown. Transfer functions for torque and speed loops are determined. Logarithmic frequency characteristics are computed. Damping properties of elevator drive system are estimated.

  16. Frequency Properties Research of Elevator Drive System with Direct Torque Control-Pulse with Modulation

    OpenAIRE

    A. S. Koval; A. V. Shvayakov

    2014-01-01

    In the article problems of frequency properties research for electric drive system with direct torque control and pulse width modulator are described. The mathematical description of elevator is present. Simplified mathematical description of direct torque control - pulse width modulator electric drive system is shown. Transfer functions for torque and speed loops are determined. Logarithmic frequency characteristics are computed. Damping properties of elevator drive system are estimated.

  17. An Observing Method for Flux and Speed with Direct Torque Control

    Institute of Scientific and Technical Information of China (English)

    祝龙记; 王汝琳

    2004-01-01

    An observing method for stator flux and rotor flux is presented. Based on the proposed flux observing method, a novel speed estimator has been designed. At last, the speed estimator combined with the flux observing is applied in the direct torque control system without speed sensor. The simulation results show that these methods can improve the accuracy of speed observing and the low speed performance of direct torque control system, and strengthen the robustness of system.

  18. Thinking as the Control of Imagination: a Conceptual Framework for Goal-Directed Systems

    OpenAIRE

    Pezzulo, Giovanni; Castelfranchi, Cristiano

    2009-01-01

    This paper offers a conceptual framework which (re)integrates goal-directed control, motivational processes, and executive functions, and suggests a developmentalpathway from situated action to higher level cognition. We first illustrate a basic computational (control-theoretic) model of goal-directed action that makes use of internalmodeling. We then show that by adding the problem of selection among multiple actionalternatives motivation enters the scene, and that the basic mechanisms of ex...

  19. Control of Linear Electrical Generators for Direct Drive Wave Energy Conversion

    OpenAIRE

    Shek, Jonathan

    2006-01-01

    Linear generators have been proposed as a suitable power take-off system for direct drive wave energy conversion. Coupled directly to a reciprocating wave energy device, it is suggested that linear generators could be a viable alternative to hydraulic and pneumatic systems. This paper discusses the challenges involved in control of a direct drive wave energy converter, predominantly for maximum power extraction through electrical means. It highlights characteristics of linear generator contro...

  20. Direct Load Control (DLC) Considering Nodal Interrupted Energy Assessment Rate (NIEAR) in Restructured Power Systems

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Wang, Peng; Goel, Lalit

    2010-01-01

    A direct load control (DLC) scheme of air conditioning loads (ACL) considering direct monetary compensation to ACL customers for the service interruption caused by the DLC program is proposed in this paper for restructured power systems. The nodal interrupted energy assessment rate (NIEAR), which...

  1. Multivariable direct adaptive decoupling controller using multiple models and a case study

    Institute of Scientific and Technical Information of China (English)

    WANG Xin; YANG Hui; ZHENG YiHui

    2009-01-01

    In this paper, a multivariable direct adaptive controller using multiple models without minimum phase assumption is presented to improve the transient response when the parameters of the system jump abruptly. The controller is composed of multiple fixed controller models, a free-running adaptive controller model and a re-initialized adaptive controller model. The fixed controller models are derived from the corresponding fixed system models directly. The adaptive controller models adopt the direct adaptive algorithm to reduce the design calculation. At every instant, the optimal controller is chosen out according to the switching index. The interaction of the system is viewed as the measured disturbance which is eliminated by the choice of the weighing polynomial matrix. The global convergence is obtained. Finally, several simulation examples in a wind tunnel experiment are given to show both effectiveness and practicality of the proposed method. The significance of the proposed method is that it is applicable to a non-minimum phase system, adopting direct adaptive algorithm to overcome the singularity problem during the matrix calculation and realizing decoupling control for a multivariable system.

  2. Fuzzy Logic Controller for Sensorless Direct Torque Control of an Induction Motor Driven by a Matrix Converter

    Directory of Open Access Journals (Sweden)

    El Mehdi Chiali

    2015-10-01

    Full Text Available The direct torque control has become one of the control techniques used for high performances. The major drawback of this strategy is its high torque ripples. This paper proposes the use of matrix converter to reduce the electromagnetic torque ripples, by suitably selecting switching configuration. This switching strategy combines the advantages of matrix converter with the advantages of direct torque control technique, using a fuzzy speed controller and MRAS speed estimator. A speed controller is designed according to the concept of fuzzy logic, to provide a good robustness to the variations of mechanical parameters. A MRAS speed estimator is also used in order to avoid the implementation of a incremental encoder.The obtained results with Matlab-Simulink show the effectiveness of the proposed system.

  3. A decentralized control method for direct smart grid control of refrigeration systems

    DEFF Research Database (Denmark)

    Shafiei, Seyed Ehsan; Izadi-Zamanabadi, Roozbeh; Rasmussen, Henrik;

    2013-01-01

    A decentralized control method is proposed to govern the electrical power consumption of supermarket refrigeration systems (SRS) for demand-side management in the smart grid. The control structure is designed in a supervisory level to provide desired set-points for distributed level controllers. No...... model information is required in this method. The temperature limits/constraints are respected. A novel adaptive saturation filter is also proposed to increase the system flexibility in storing and delivering the energy. The proposed control strategy is applied to a simulation benchmark that fairly...

  4. Direct adaptive control of wind energy conversion systems using Gaussian networks.

    Science.gov (United States)

    Mayosky, M A; Cancelo, I E

    1999-01-01

    Grid connected wind energy conversion systems (WECS) present interesting control demands, due to the intrinsic nonlinear characteristics of windmills and electric generators. In this paper a direct adaptive control strategy for WECS control is proposed. It is based on the combination of two control actions: a radial basis zfunction network-based adaptive controller, which drives the tracking error to zero with user specified dynamics, and a supervisory controller, based on crude bounds of the system's nonlinearities. The supervisory controller fires when the finite neural-network approximation properties cannot be guaranteed. The form of the supervisor control and the adaptation law for the neural controller are derived from a Lyapunov analysis of stability. The results are applied to a typical turbine/generator pair, showing the feasibility of the proposed solution. PMID:18252585

  5. Velocity Control for Coning Motion Missile System Using Direct Discretization Method

    Directory of Open Access Journals (Sweden)

    Rui-sheng Sun

    2015-01-01

    Full Text Available This paper presents a new coning motion control methodology, which takes into account the terminal speed constraint to design the velocity control system for a missile. By using a direct discretization method to transform the optimal control problem into a nonlinear dynamic programming problem, the optimal trajectory and velocity profile are obtained to satisfy the design index requirement. In order to perform the velocity control, a virtual moving target is proposed for the missile to chase along the optimized trajectory. Consequently, after building velocity control model, a velocity control law and control parameters of the coning motion are completed through the dynamic inversion theory. The simulation results suggest that the proposed control law has a good performance and could be applied to the guidance for the missile with terminal speed control constraint.

  6. A Fault Tolerant Direct Control Allocation Scheme with Integral Sliding Modes

    Directory of Open Access Journals (Sweden)

    Hamayun Mirza Tariq

    2015-03-01

    Full Text Available In this paper, integral sliding mode control ideas are combined with direct control allocation in order to create a fault tolerant control scheme. Traditional integral sliding mode control can directly handle actuator faults; however, it cannot do so with actuator failures. Therefore, a mechanism needs to be adopted to distribute the control effort amongst the remaining functioning actuators in cases of faults or failures, so that an acceptable level of closed-loop performance can be retained. This paper considers the possibility of introducing fault tolerance even if fault or failure information is not provided to the control strategy. To demonstrate the efficacy of the proposed scheme, a high fidelity nonlinear model of a large civil aircraft is considered in the simulations in the presence of wind, gusts and sensor noise.

  7. A Direct Compensative Robust Optimal Control (DCROC) Law for Ship Straight-line Track-keeping

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A linear quadratic optimal direct track-keeping control law was proposed based on first-order Nomoto nominal model. Furthermore, based on Lyapunov stabilized theory, considering parametric uncertainty from variations of ship speed and disturbances uncertain from wind, wave and sea current, a direct compensative robust optimal control (DCROC) law was developed. It can guarantee closed-loop system globally and uniformly converge to a remained set. High accuracy and robustness were achieved. By introducing some nonlinear blocks, closed-loop system achieves global and uniform asymptotical stableness. Numerical simulations on a Mariner Class ship are presented to validate the control law.

  8. Hybrid Asymmetric Space Vector Modulation for inverter based direct torque control induction motor drive

    Directory of Open Access Journals (Sweden)

    Nandakumar Sundararaju

    2014-05-01

    Full Text Available This paper proposes novel hybrid asymmetric space vector modulation technique for inverter operated direct torque control induction motor drive. The hybridization process is performed by the combination of continuous asymmetric space vector modulation pulse width technique (ASVPWM and fuzzy operated discontinuous ASVPWM technique. Combination process is based on pulse mismatching technique. Pulse mismatching technique helps to reduce the active region of the switch. Finally, optimal pulses are applied to control the inverter. The optimal hybrid pulse condense switching losses of the inverter and also improves the operating performance of the direct torque control (DTC based drive system like smooth dynamic response in speed reversal, minimum torque error, settling time of speed. Simulation results of proposed hybrid asymmetric space vector pulse width modulation technique to direct torque control (HASVPWM-DTC approach has been carried out by using Matlab-Simulink environment.

  9. Direct Torque Control of Induction Motor Drive Fed from a Photovoltaic Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Mahrous Ahmed

    2014-09-01

    Full Text Available This paper presents Direct Torque Control (DTC using Space Vector Modulation (SVM for an induction motor drive fed from a photovoltaic multilevel inverter (PV-MLI. The system consists of two main parts PV DC power supply (PVDC and MLI. The PVDC is used to generate DC isolated sources with certain ratios suitable for the adopted MLI. Beside the hardware system, the control system which uses the torque and speed estimation to control the load angle and to obtain the appropriate flux vector trajectory from which the voltage vector is directly derived based on direct torque control methods. The voltage vector is then generated by a hybrid multilevel inverter by employing space vector modulation (SVM. The inverter high quality output voltage which leads to a high quality IM performances. Besides, the MLI switching losses is very low due to most of the power cell switches are operating at nearly fundamental frequency. Some selected simulation results are presented for system validation.

  10. Controllability analysis of second-order multi-agent systems with directed and weighted interconnection

    Institute of Scientific and Technical Information of China (English)

    Di GUO; Rong-hao ZHENG; Zhi-yun LIN; Gang-feng YAN

    2015-01-01

    This article investigates the controllability problem of multi-agent systems. Each agent is assumed to be governed by a second-order consensus control law corresponding to a directed and weighted graph. Two types of topology are considered. The fi rst is concerned with directed trees, which represent the class of topology with minimum information exchange among all controllable topologies. A very simple necessary and suffcient condition regarding the weighting scheme is obtained for the controllability of double integrator multi-agent systems in this scenario. The second is concerned with a more general graph that can be reduced to a directed tree by contracting a cluster of nodes to a component. A similar necessary and suffcient condition is derived. Finally, several illustrative examples are provided to demonstrate the theoretical analysis results.

  11. Direct Torque Control Strategy for Doubly Fed Induction Machine under Low Voltage Dips

    Directory of Open Access Journals (Sweden)

    Venu Madhav Gopala

    2012-10-01

    Full Text Available This paper proposes a control strategy of generating a rotor flux amplitude reference for Doubly Fed Induction Machine (DFIM based wind turbines. In addition to that a Direct Torque Control (DTC strategy that provides fast dynamic response accompanies the overall control of the wind turbine. It is specially designed to address perturbations, such as voltage dips, keeping controlled the torque of the wind turbine, considerably reducing the stator and rotor over currents during faults. Despite the fact that the proposed control does not totally eliminate the necessity of the typical crowbar protection for this kind of turbines, it eliminates the activation of this protection during low depth voltage dips.

  12. Direct torque control design and experimental evaluation for the brushless doubly fed machine

    International Nuclear Information System (INIS)

    In this paper, a direct torque control (DTC) strategy for the brushless doubly fed machine (BDFM) is presented. After analyzing the mathematical model of this machine, the voltage vectors look-up table of classical DTC techniques is derived. Then, the behavior of the machine is studied when it is controlled by the developed DTC technique, concluding that under some specific operation conditions, a BDFM could present a time interval where the torque and the flux can not be controlled simultaneously. In these cases, two different control solutions have been defined: 'flux priority' and 'torque priority'. Finally, simulation and experimental results validate the effectiveness of the proposed control algorithms.

  13. Direct torque control via feedback linearization for permanent magnet synchronous motor drives

    DEFF Research Database (Denmark)

    Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede

    The paper describes a direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive that employs feedback linearization and uses sliding-mode and linear controllers. We introduce a new feedback linearization approach that yields a decoupled linear PMSM model with two state...... variable structure controller (VSC) which is robust, fast, and produces low-ripple control is compared with a linear-DTC scheme which is ripple free. The torque time response is similar to a conventional DTC drive and the proposed solutions are flexible and highly tunable. We present the controller design...... and analyze the robust stability. Experimental results for a sensorless PMSM drive validate the proposed solution....

  14. Distributed Voltage and Current Control of Multi-Terminal High-Voltage Direct Current Transmission Systems

    OpenAIRE

    Andreasson, Martin; Nazari, Mohammad; Dimarogonas, Dimos V.; Sandberg, Henrik; Johansson, Karl H.; Ghandhari, Mehrdad

    2014-01-01

    High-voltage direct current (HVDC) is a commonly used technology for long-distance power transmission, due to its low resistive losses and low costs. In this paper, a novel distributed controller for multi-terminal HVDC (MTDC) systems is proposed. Under certain conditions on the controller gains, it is shown to stabilize the MTDC system. The controller is shown to always keep the voltages close to the nominal voltage, while assuring that the injected power is shared fairly among the converter...

  15. Minimization of torque ripple in switched reluctance motor drives using an enhanced direct instantaneous control

    OpenAIRE

    Castro Soriano, Javier; Andrada Gascón, Pedro; Blanqué Molina, Balduino

    2012-01-01

    Torque ripple is an inherent characteristic of switched reluctance motor drives due to its double salient geometry and it is a serious drawback in applications that require smooth torque and high dynamic performances. This paper presents new contributions to the minimization of torque ripple in SRM using an enhanced direct instantaneous torque control. Torque ripple is reduced by adding a PI controller before the instantaneous torque controller and a change in the commutation zones. The...

  16. Modified direct torque control method for induction motor drives based on amplitude and angle control of stator flux

    Energy Technology Data Exchange (ETDEWEB)

    Kumsuwan, Yuttana; Premrudeepreechacharn, Suttichai [Department of Electrical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai 50200 (Thailand); Toliyat, Hamid A. [Department of Electrical and Computer Engineering, Texas A and M University, College Station, TX 77843-3128 (United States)

    2008-10-15

    This paper proposes design and implementation of a direct torque controlled induction motor drive system. The method is based on control of separation between amplitude and angle of reference stator flux for determining reference stator voltage vector in generating PWM output voltage for induction motors. The objective is to reduce electromagnetic torque ripple and stator flux droop which result in a decrease in current distortion in steady-state condition. In addition, the proposed technique provides simplicity of a control system. The direct torque control is based on the relationship between instantaneous slip angular frequency and rotor angular frequency in adjustment of the reference stator flux angle. The amplitude of the reference stator flux is always kept constant at rated value. The system has been implemented to verify its capability such as torque and stator flux responses, stator phase current distortion both during dynamic and steady state with load variation, and low speed operation. (author)

  17. DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)

    DEFF Research Database (Denmark)

    Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede

    2002-01-01

    DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...

  18. Bat algorithm optimized fuzzy PD based speed controller for brushless direct current motor

    Directory of Open Access Journals (Sweden)

    K. Premkumar

    2016-06-01

    Full Text Available In this paper, design of fuzzy proportional derivative controller and fuzzy proportional derivative integral controller for speed control of brushless direct current drive has been presented. Optimization of the above controllers design is carried out using nature inspired optimization algorithms such as particle swarm, cuckoo search, and bat algorithms. Time domain specifications such as overshoot, undershoot, settling time, recovery time, and steady state error and performance indices such as root mean squared error, integral of absolute error, integral of time multiplied absolute error and integral of squared error are measured and compared for the above controllers under different operating conditions such as varying set speed and load disturbance conditions. The precise investigation through simulation is performed using simulink toolbox. From the simulation test results, it is evident that bat optimized fuzzy proportional derivative controller has superior performance than the other controllers considered. Experimental test results have also been taken and analyzed for the optimal controller identified through simulation.

  19. A predictive current control applied to a permanent magnet synchronous machine, comparison with a classical direct torque control

    Energy Technology Data Exchange (ETDEWEB)

    Morel, Florent; Lin-Shi, Xuefang; Retif, Jean-Marie; Allard, Bruno [AMPERE, INSA de Lyon, 20, avenue Albert Einstein, 69621 Villeurbanne cedex (France)

    2008-08-15

    This paper presents a new predictive current control (PCC) for permanent magnet synchronous machines (PMSM) drivers. Based on a hybrid model including an inverter model and a PMSM model, the proposed scheme selects more than one inverter configuration and allows to reach exactly the reference state vector. It appears attractive when compared to conventional direct torque control (DTC). Hysteresis comparators are not used. The switching frequency is fixed and it does not have to be very high. The control scheme has been verified experimentally with a 1.6 kW PMSM drive. Comparative studies with DTC control are performed with the same test bench. The results show that the proposed control obtains the same fast torque dynamics if not better than DTC control schemes but with smaller ripples. (author)

  20. Direct yaw moment control for distributed drive electric vehicle handling performance improvement

    Science.gov (United States)

    Yu, Zhuoping; Leng, Bo; Xiong, Lu; Feng, Yuan; Shi, Fenmiao

    2016-05-01

    For a distributed drive electric vehicle (DDEV) driven by four in-wheel motors, advanced vehicle dynamic control methods can be realized easily because motors can be controlled independently, quickly and precisely. And direct yaw-moment control (DYC) has been widely studied and applied to vehicle stability control. Good vehicle handling performance: quick yaw rate transient response, small overshoot, high steady yaw rate gain, etc, is required by drivers under normal conditions, which is less concerned, however. Based on the hierarchical control methodology, a novel control system using direct yaw moment control for improving handling performance of a distributed drive electric vehicle especially under normal driving conditions has been proposed. The upper-loop control system consists of two parts: a state feedback controller, which aims to realize the ideal transient response of yaw rate, with a vehicle sideslip angle observer; and a steering wheel angle feedforward controller designed to achieve a desired yaw rate steady gain. Under the restriction of the effect of poles and zeros in the closed-loop transfer function on the system response and the capacity of in-wheel motors, the integrated time and absolute error (ITAE) function is utilized as the cost function in the optimal control to calculate the ideal eigen frequency and damper coefficient of the system and obtain optimal feedback matrix and feedforward matrix. Simulations and experiments with a DDEV under multiple maneuvers are carried out and show the effectiveness of the proposed method: yaw rate rising time is reduced, steady yaw rate gain is increased, vehicle steering characteristic is close to neutral steer and drivers burdens are also reduced. The control system improves vehicle handling performance under normal conditions in both transient and steady response. State feedback control instead of model following control is introduced in the control system so that the sense of control intervention to

  1. Multifunctional four-port directional control valve constructed from logic valves

    International Nuclear Information System (INIS)

    Highlights: • Directional valve with standard ISO 440-08 has been constructed from logic valves. • Only one innovative valve may replace whole family of the standard valves. • CFD analysis and bench tests of the innovative valve has been carried. • Parameters of the innovative valve are equaling or surpassing the standard ones. • The innovative valve has additional possibilities of pressure and flow control. - Abstract: The paper refers to four-port solenoid pilot operated valves, which are subplate mounted in a hydraulic system in accordance with the ISO 4401 standard. Their widespread use in many machines and devices causes a continuing interest in the development of their design by both the scientific centers and the industry. This paper presents an innovative directional control valve based on the use of logic valves and a methodology followed for the design of it by using Solid Edge CAD and ANSYS/Fluent CFD software. The valve design methodology takes into account the need to seek solutions that minimize flow resistance through the valve. For this purpose, the flow paths are prepared by means of CAD software and pressure-flow curves are determined as a result of CFD analysis. The obtained curves are compared with the curves available in the catalogs of spool type directional control valves. The new solution allows to replace the whole family of spool type four-port directional control valves by one valve built of logic valves. In addition, the innovative directional control valve provides leak-proof shutting the flow paths off and also it can control flow rate and even pressure of working liquid. A prototype of the valve designed by the presented method has been made and tested on the test bench. The results quoted in the paper confirm that the developed logic type directional control valve is able to meet all designed connection configurations, and the obtained pressure-flow curves show very good conformity with the results of CFD analysis

  2. A new direct torque control scheme for induction motors using linear state feedback

    Energy Technology Data Exchange (ETDEWEB)

    Kandianis, A.; Manias, S.N. [National Technical Univ. of Athens (Greece). Dept. of Electrical Engineering; Griva, G.; Profumo, F. [Politecnico di Torino (Italy). Dept. of Electrical Engineering

    1995-12-31

    In this paper a new Direct Torque Control (DTC) scheme for induction motor drives is described, based on the linear state feedback method with dynamic output feedback. The DTC has been shown to be a good solution in torque controlled drives applications when the speed control is not required (e.g. traction drives for electric vehicles). In such cases, the torque command comes directly from the user input. By considering the torque and flux as the outputs of the linearized motor model, it is possible to design an optimum controller with constant gain state feedback and dynamic output feedback through an integral term. The design procedure of the proposed control scheme is described and the simulation results are presented to show the overall performance of the system.

  3. Direct Torque Control of Sensorless Induction Motor Drives: A Sliding-Mode Approach

    DEFF Research Database (Denmark)

    Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede

    2004-01-01

    Direct torque control (DTC) is known to produce fast response and robust control in ac adjustable-speed drives. However, in the steady-state operation, notable torque, flux, and current pulsations occur. A new, direct torque and flux control strategy based on variable-structure control and space......-vector pulsewidth modulation is proposed for induction motor sensorless drives. The DTC transient merits and robustness are preserved and the steady-state behaviour is improved by reducing the torque and flux pulsations. A sliding-mode observer using a dual reference frame motor model is introduced and tested....... Simulations and comparative experimental results with the proposed control scheme, versus classic DTC, are presented. Very-low-speed sensorless operation (3 r/min) is demonstrated....

  4. Decentralized direct adaptive neural network control for a class of interconnected systems

    Institute of Scientific and Technical Information of China (English)

    Zhang Tianping; Mei Jiandong

    2006-01-01

    The problem of direct adaptive neural network control for a class of large-scale systems with unknown function control gains and the high-order interconnections is studied in this paper. Based on the principle of sliding mode control and the approximation capability of multilayer neural networks, a design scheme of decentralized direct adaptive sliding mode controller is proposed. The plant dynamic uncertainty and modeling errors are adaptively compensated by adjusted the weights and sliding mode gains on-line for each subsystem using only local information. According to the Lyapunov method, the closed-loop adaptive control system is proven to be globally stable, with tracking errors converging to a neighborhood of zero. Simulation results demonstrate the effectiveness of the proposed approach.

  5. Global Inverse Optimal Tracking Control of Underactuated Omni-directional Intelligent Navigators (ODINs)

    Institute of Scientific and Technical Information of China (English)

    Khac Duc Do

    2015-01-01

    This paper presents a design of optimal controllers with respect to a meaningful cost function to force an underactuated omni-directional intelligent navigator (ODIN) under unknown constant environmental loads to track a reference trajectory in two-dimensional space. Motivated by the vehicle’s steering practice, the yaw angle regarded as a virtual control plus the surge thrust force are used to force the position of the vehicle to globally track its reference trajectory. The control design is based on several recent results developed for inverse optimal control and stability analysis of nonlinear systems, a new design of bounded disturbance observers, and backstepping and Lyapunov’s direct methods. Both state- and output-feedback control designs are addressed. Simulations are included to illustrate the effectiveness of the proposed results.

  6. Experimental Investigations on the Influence of Flux Control Loop in a Direct Torque Control Drive.

    Directory of Open Access Journals (Sweden)

    bhoopendra singh

    2012-10-01

    Full Text Available

    Accurate flux estimation and control of stator flux by the flux control loop is the determining factor in effective implementation of DTC algorithm. In this paper a comparison of voltage model based flux estimation techniques for flux response improvement is carried out. The effectiveness of these methods is judged on the basis of Root Mean Square Flux Error (RMSFE and Total Harmonic Distortion (THD of stator current. The theoretical aspects of these methods are discussed and a comparative analysis is provided with emphasis on digital signal processor (DSP based controller implementation. Further the effect of operating flux on the performance of induction motor drive in terms of dynamic response, torque ripple and efficiency of operation is carried out. The proposed investigation is experimentally validated on a test drive.

  7. Comparison of pulsed fluoroscopy by direct control using a grid-controlled x-ray tube with pulsed fluoroscopy by primary control

    International Nuclear Information System (INIS)

    Interventional radiology (IVR) procedures may involve high radiation doses that are potentially harmful to the patient. In IVR procedures, pulsed fluoroscopy can greatly decrease the radiation that the physician and patient receive. There are two types of pulsed fluoroscopy: direct control and primary (indirect) control. The purpose of this study was to compare pulsed fluoroscopy by direct control, using a grid-controlled x-ray tube, with pulsed fluoroscopy using primary control. For both types of pulsed fluoroscopy, we measured the waveforms (x-ray tube voltage, x-ray tube current, and x-ray output) and the relative radiation dose. In addition, we compared the decrease in radiation during pulsed fluoroscopy using a care filter. The studies were performed using a Siemens Bicor Plus x-ray System (direct control) and a Siemens Multistar Plus x-ray System (primary control). Using primary pulse control, a 50% decrease in the x-ray output waveform took approximately 0.5-1.0 msec, or longer with a lower x-ray tube current. Using direct pulse control, a 50% decrease in the x-ray output waveform took approximately 0.1 msec, and was independent of x-ray tube current. The rate of radiation reduction with primary pulse control using the care filter with a lower x-ray tube current had a slope exceeding 10%. Pulsed fluoroscopy by direct control using a grid-controlled x-ray tube permits an optimal radiation dose. To decrease the radiation in primary pulse control, a care filter must be used, particularly with a lower x-ray tube current. (author)

  8. Control of Basal Ganglia Output by Direct and Indirect Pathway Projection Neurons

    OpenAIRE

    Freeze, Benjamin S.; Kravitz, Alexxai V.; Hammack, Nora; Berke, Joshua D.; Kreitzer, Anatol C.

    2013-01-01

    The direct and indirect efferent pathways from striatum ultimately reconverge to influence basal ganglia output nuclei, which in turn regulate behavior via thalamocortical and brainstem motor circuits. However, the distinct contributions of these two efferent pathways in shaping basal ganglia output are not well understood. We investigated these processes using selective optogenetic control of the direct and indirect pathways, in combination with single-unit recording in the basal ganglia out...

  9. Direct Suppression as a Mechanism for Controlling Unpleasant Memories in Daily Life

    OpenAIRE

    Küpper, Charlotte S.; Benoit, Roland G.; Dalgleish, Tim; Anderson, Michael C.

    2014-01-01

    Suppressing unwanted memories can impair their later recall. Recent work shows that this forgetting is achieved by at least two mechanisms supported by distinct neural systems: thought substitution and direct suppression (Benoit & Anderson, 2012). Here, we examined whether direct suppression, thought to be achieved by down-regulation of hippocampal activity, can disrupt memory of aversive scenes, and, if so, whether this disruption is linked to people’s perception of their ability to control ...

  10. Sliding mode pulse-width modulation technique for direct torque controlled induction motor drive

    Science.gov (United States)

    Bounadja, M.; Belarbi, A. W.; Belmadani, B.

    2010-05-01

    This paper presents a novel pulse-width modulation technique based sliding mode approach for direct torque control of an induction machine drive. Methodology begins with a sliding mode control of machine's torque and stator flux to generate the reference voltage vector and to reduce parameters sensitivity. Then, the switching control of the three-phase inverter is developed using sliding mode concept to make the system tracking reference voltage inputs. The main features of the proposed methodologies are the high tracking accuracy and the much easier implementation compared to the space vector modulation. Simulations are carried out to confirm the effectiveness of proposed control algorithms.

  11. Direct suppression as a mechanism for controlling unpleasant memories in daily life.

    Science.gov (United States)

    Küpper, Charlotte S; Benoit, Roland G; Dalgleish, Tim; Anderson, Michael C

    2014-08-01

    Suppressing unwanted memories can impair their later recall. Recent work shows that this forgetting is achieved by at least two mechanisms supported by distinct neural systems: thought substitution and direct suppression (Benoit & Anderson, 2012). Here, we examined whether direct suppression, thought to be achieved by down-regulation of hippocampal activity, can disrupt memory of aversive scenes, and, if so, whether this disruption is linked to people's perception of their ability to control intrusive thoughts. We presented participants with strong naturalistic reminders to aversive scenes and asked them to either covertly retrieve or directly suppress the associated scenes. Later, participants were cued with the reminders and asked to recall the scenes in detail. Direct suppression reduced recall probability of the scenes and also reduced the number of details recalled, even when scenes were remembered. Deficits in recall arose for minor details but also for details central to each scene's gist. Participants with higher self-perceived control abilities over intrusive thoughts showed greater forgetting than did those reporting lower levels of control. These findings suggest that inhibitory processes underlying direct suppression can disrupt retention of aversive visual memories and link those processes to individual differences in control over intrusive thoughts in everyday life. These findings reinforce the possibility that inhibition may be less efficient in people likely to acquire posttraumatic stress disorder in the wake of a traumatic experience. PMID:24749897

  12. Direct torque control of six-phase induction motors using three-phase matrix converter

    Energy Technology Data Exchange (ETDEWEB)

    Talaeizadeh, V., E-mail: valitalaeezadeh@yahoo.co [Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Kianinezhad, R.; Seyfossadat, S.G. [Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Shayanfar, H.A. [The Center of Excellence for Power System Automation and Operation, Department of Electrical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2010-12-15

    This paper presents a new direct torque control (DTC) method for six-phase induction motor (SPIM). In the proposed method, direct torque and flux control are applied to the SPIM using matrix converter with the conventional three-phase source as its input. The new DTC scheme for SPIM benefits the advantages of both DTC and matrix converter, such as unity power factor and absence of dc-link. The simulation results show the effectiveness of the proposed method in both dynamic and steady state response.

  13. Direct torque control of six-phase induction motors using three-phase matrix converter

    International Nuclear Information System (INIS)

    This paper presents a new direct torque control (DTC) method for six-phase induction motor (SPIM). In the proposed method, direct torque and flux control are applied to the SPIM using matrix converter with the conventional three-phase source as its input. The new DTC scheme for SPIM benefits the advantages of both DTC and matrix converter, such as unity power factor and absence of dc-link. The simulation results show the effectiveness of the proposed method in both dynamic and steady state response.

  14. Senserless Speed and Position of Direct Field Orientation Control Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    Mohammed Khalil Hussain

    2012-01-01

    Full Text Available Direct field-orientation Control (DFOC of induction motor drives without mechanical speed sensors at the motor shaft has the attractions of low cost and high reliability. To replace the sensor, information on the rotor speed and position are extracted from measured stator currents and from voltages at motor terminals. In this paper presents direct field-orientation control (DFOC with two type of kalman filter (complete order and reduced order extended kalman filter to estimate flux, speed, torque and position. Simulated results show how good performance for reduced order extended kalman filter over that of complete order extended kalman filter in tracking performance and reduced time of state estimation.

  15. Distributed H∞ control of multi-agent systems with directed networks

    Science.gov (United States)

    Liu, Wei; Liu, Ai-Li; Zhou, Shao-Lei

    2015-09-01

    This paper studies the distributed H∞ control problem of identical linear time invariant multi-agent systems subject to external disturbances. A directed graph containing a spanning tree is used to model the communication topology. Based on the relative states of the neighbor agents and a subset of absolute states of the agents, distributed static H∞ controllers are proposed. The concept of an H∞ performance region is extended to the directed graph situation. Then the results are used to solve the leader-follower H∞ consensus problem. Sufficient conditions are proposed based on bounded real lemma and algebraic graph theory. The effectiveness of the theoretical results is illustrated via numerical simulations.

  16. Performances improvements and torque ripple minimization for VSI fed induction machine with direct control torque.

    Science.gov (United States)

    Abdelli, R; Rekioua, D; Rekioua, T

    2011-04-01

    This paper describes a torque ripple reduction technique with constant switching frequency for direct torque control (DTC) of an induction motor (IM). This method enables a minimum torque ripple control. In order to obtain a constant switching frequency and hence a torque ripple reduction, we propose a control technique for IM. It consists of controlling directly the electromagnetic torque by using a modulated hysteresis controller. The design methodology is based on space vector modulation (SVM) of electrical machines with digital vector control. MATLAB simulations supported with experimental study are used. The simulation and experimental results of this proposed algorithm show an adequate dynamic to IM; however, the research can be extended to include synchronous motors as well. The implementation of the proposed algorithm is described. It doesn't require any PI controller in the torque control loop. The hardware inverter is controlled digitally using a Texas Instruments TMS320F240 digital signal processor (DSP) with composed C codes for generating the required references. The results obtained from simulation and experiments confirmed the feasibility of the proposed strategy compared to the conventional one. PMID:21193193

  17. A direct torque control scheme for permanent magnet synchronous motors based on space vector modulation

    Science.gov (United States)

    Su, Xiao-hui; Xu, Shu-Ping

    2013-03-01

    In order to solve the problem of direct torque control (DTC) for permanent magnet synchronous motor (PMSM) related to the flux and the torque ripple and the uncertainty of switching frequency, A novel direct torque control system based on space vector modulation(SVM-DTC) for permanent magnet synchronous motor was proposed. In this method flux and torque are controlled through stator voltage components in stator flux linkage coordinate axes and space vector modulation is used to control inverters. Therefore, the errors of torque and flux linkage could be compensated accurately. The whole system has only one easily adjustable PI adjuster and needs no high for hardware and easy for realize. The simulation results verify the feasibility of this method, reduction of the flux and the torque ripple, and the good performance of DTC.

  18. The planned EC Directive on 'Integrated Pollution Prevention and Control' (IPC)

    International Nuclear Information System (INIS)

    This EC Directive is intended to incorporate integrated pollution control as a mandatory obligation in the legal provisions governing industrial installations licensing within the EC. The article in hand presents an assessment of the Directive and discusses some possible impacts on the German national law in the field of pollution control, which hitherto has been defined on the basis of a preferably medium-oriented approach. A serious point of deviation from the German approach is seen in the fact that the draft's provisions relating to the licensing of industrial installations defines certain pre-conditions allowing a plant in a low-polluted area to be licensed, although the pollution control systems of the plant do not them come up to the state-of-the-art in pollution abatement technology. This is seen as a fact jeopardizing the principle of precantionary measures which has been firmly established in German pollution control law. (orig./HP)

  19. Analysis, Evaluation and Simulation of Direct Torque Control of Induction Motor Using SVPWM Technique

    Directory of Open Access Journals (Sweden)

    Seema Kumari*1,

    2014-06-01

    Full Text Available Induction machine drive based on Direct Torque Control (DTC allows high dynamic performance with very simple hysteresis control scheme. Conventional Direct Torque Control (CDTC suffers from some drawbacks such as high torque ripple and variable switching frequency, difficulties in torque as well as flux control at very low speed. This paper is aimed to analyze DTC principles, the strategies and the problems related to its implementation and the possible improvements using Space Vector Pulse Width Modulation (SVPWM. In SVPWM for each sampling period the switching instants of different space vectors are determined to reduce torque ripple. A comparison study between SVPWM-DTC and CDTC is carried out to apply switching select voltage vector. The theoretical foundation principle, the numerical simulation procedure and the performances of both methods are also presented.

  20. Improving the performance of hysteresis direct torque control of IPMSM using active filter topology

    Indian Academy of Sciences (India)

    Kayhan Gulez; Ali Ahmed Adam; Halit Pastaci

    2006-06-01

    This paper describes an active filter topology to improve the performance of hysteresis direct torque control (HDTC) of interior permanent magnet synchronous motor (IPMSM). The filter topology consists of an active filter and two RLC filters, and is connected to the main power circuit through a 1:1 transformer. The active filter is characterized by detecting the harmonics in the motor phase voltages and injecting equivalent harmonic voltages to produce almost sinusoidal voltage waveform to the motor terminals. The active filter uses hysteresis voltage controller while the motor main circuit uses hysteresis direct torque control. The simulation results of this combined control structure show considerable torque ripple reduction in the steady state range and adequate dynamic torque performance as well as considerable harmonic voltage and EMI noise reduction.

  1. Speed control of induction machine based on direct torque control method

    OpenAIRE

    Mascarenhas, Manuel Maria Brás Pereira

    2013-01-01

    Multi-level converters have been receiving attention in the recent years and have been proposed as the best choice in a wide variety of medium voltage applications. They enable a commutation at substantially reduced voltages and an improved harmonic spectrum without a series connection of devices, which is the main advantage of a multi-level structure. The use of multi-level inverters contributes to the performances amelioration of the induction machine control. In fact, the use of three l...

  2. Implementation of Directional Control System for Autonomous Robot Based on Voice Command Controller

    OpenAIRE

    Han Nilar Htay; Hla Myo Tun

    2014-01-01

    The main idea of this research is to process analog voice signal. The paper is implemented for controlling the robot by voice command. The implemented system involves voice recognition unit, digital data processing unit with DC switching section. The proposed system consists of a microcontroller and a voice recognition processor that can recognize a limited number of voice patterns. This is voice based guidance system, which uses the special voice recognition IC HM2007 for speech enhancement....

  3. Direct torque control for dual three-phase induction motor drives

    OpenAIRE

    Farina, Francesco; PROFUMO Francesco; Griva, Giovanni Battista; TENCONI Alberto; Bojoi, Iustin Radu

    2005-01-01

    A direct torque control (DTC) strategy for dual three-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The DTC strategy is based on a predictive algorithm and is implemented in a synchronous reference frame aligned with the machine stator flux vector. The advantages of the discussed control strategy are constant inverter switching frequency, good transient and steady-state per...

  4. A DSP-based discrete space vector modulation direct torque control of sensorless induction machines

    Energy Technology Data Exchange (ETDEWEB)

    Khoucha, F.; Marouani, K.; Kheloui, A.; Aliouane, K.

    2004-07-01

    In this paper, we present a Direct Torque Control scheme of an induction motor operating without speed sensor. The estimation of the stator flux and the rotor speed is performed by an adaptive observer. In order to reduce the torque, flux, current and speed ripple a Discrete Space Vector Modulation (DSVM-DTC) strategy is implemented using a DSP-based hardware. To illustrate the performances of this control scheme, experimental results are presented. (author)

  5. Direct torque control of brushless DC drives with reduced torque ripple

    OpenAIRE

    Liu, Y.; Zhu, Z Q; Howe, D

    2005-01-01

    The application of direct torque control (DTC) to brushless ac drives has been investigated extensively. This paper describes its application to brushless dc drives, and highlights the essential differences in its implementation, as regards torque estimation and the representation of the inverter voltage space vectors. Simulated and experimental results are presented, and it is shown that, compared with conventional current control, DTC results in reduced torque ripple and a faster dynamic re...

  6. A novel speed sensorless direct torque control system for mining locomotive haulage

    Energy Technology Data Exchange (ETDEWEB)

    Ma, X. [Xi' an University of Science and Technology, Xi' an (China). Automation Department

    2002-06-01

    A novel speed sensorless direct torque control induction motor drive system for the mining locomotive haulage is presented in the paper. Rotor speed identification is based on the model reference adaptive control theory with neural network using back propagation algorithm. The system is implemented using a realtime TMS320F240 digital signal processor. The simulation study and experiment results indicate that the suggested system has good performance. 3 refs., 7 figs.

  7. Temperature modeling and control of Direct Methanol Fuel Cell based on adaptive neural fuzzy technology

    Institute of Scientific and Technical Information of China (English)

    Qi Zhidong; Zhu Xinjian; Cao Guangyi

    2006-01-01

    Aiming at on-line controlling of Direct Methanol Fuel Cell (DMFC) stack, an adaptive neural fuzzy inference technology is adopted in the modeling and control of DMFC temperature system. In the modeling process, an Adaptive Neural Fuzzy Inference System (ANFIS) identification model of DMFC stack temperature is developed based on the input-output sampled data, which can avoid the internal complexity of DMFC stack. In the controlling process, with the network model trained well as the reference model of the DMFC control system, a novel fuzzy genetic algorithm is used to regulate the parameters and fuzzy rules of a neural fuzzy controller. In the simulation, compared with the nonlinear Proportional Integral Derivative (PID) and traditional fuzzy algorithm, the improved neural fuzzy controller designed in this paper gets better performance, as demonstrated by the simulation results.

  8. Guest Editorial Special Issue on Recent Advances and New Directions in Switched Control Systems

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ As guest editors, it is our great honor to bring this special issue of the Journal of Control Theory and Applications devoted to Recent Advances and New Directions in Switched Control Systems. Recently, switched control systems have attracted much attention in the control systems community. Problems in this area are not only academically challenging for the inherent mathematical complexity, but also are derived or motivated from advanced applications in natural sciences, engineering, and social sciences. For survival, natural biological systems switch their survival strategies in accordance with environmental changes. For improved performance, switching has been extensively utilized/exploited in engineering systems such as automotive drive train control, electronic devices, control of power systems, etc.

  9. Controllability of heterogeneous multi-agent systems under directed and weighted topology

    Science.gov (United States)

    Guan, Yongqiang; Ji, Zhijian; Zhang, Lin; Wang, Long

    2016-05-01

    This paper considers the controllability problem for both continuous- and discrete-time linear heterogeneous multi-agent systems with directed and weighted communication topology. First, two kinds of neighbour-based control protocols based on the distributed protocol of first-order and second-order multi-agent systems are proposed, under which it is shown that a heterogeneous multi-agent system is controllable if the underlying communication topology is controllable. Then, under special leader selection, the result shows that the controllability of a heterogeneous multi-agent system is solely decided by its communication topology graph. Furthermore, some necessary and/or sufficient conditions are derived for controllability of communication topology from algebraic and graphical perspectives. Finally, simulation examples are presented to demonstrate the effectiveness of the theoretical results.

  10. H∞ controller design for a 4-meter direct-drive azimuth axis

    Science.gov (United States)

    Chen, Li-Yan; Zhang, Zhen-Chao; Song, Xiao-Li; Wang, Da-Xing

    2015-11-01

    To pursue a higher imaging resolution for exploring more details in the information conveyed by the Universe, the next generation of optical telescopes based on a direct drive widely employ the extremely large aperture structure, which also introduces more disturbances and uncertain factors to the control system. Facing this new challenge, the PID control method in main-axis control systems of traditional astronomical telescopes cannot suffice for the requirement of the tracking precision and disturbance sensitivity in angular velocity. To overcome this shortcoming, we establish a dynamic model and propose an H∞ controller for a 4-meter azimuth direct drive control system that consists of a revolving platform (azimuth axis), a three-phase torque motor, a motor drive, an encoder, a data acquisition card and a small computers. Simulations are carried out to analyze the model and guide the real experiments. Experimental results show that the proposed H∞ controller reduces the tracking error by a maximum of 80.69% (average 57.8%) and the disturbance sensitivity by a maximum of 82.3% (average 50.96%) compared with the traditional tuned PI controller; furthermore, the order of the model describing the proposed controller can be reduced to three, thus its feasibility in real systems is guaranteed.

  11. High-performance adaptive intelligent Direct Torque Control schemes for induction motor drives

    Directory of Open Access Journals (Sweden)

    Vasudevan M.

    2005-01-01

    Full Text Available This paper presents a detailed comparison between viable adaptive intelligent torque control strategies of induction motor, emphasizing advantages and disadvantages. The scope of this paper is to choose an adaptive intelligent controller for induction motor drive proposed for high performance applications. Induction motors are characterized by complex, highly non-linear, time varying dynamics, inaccessibility of some states and output for measurements and hence can be considered as a challenging engineering problem. The advent of torque and flux control techniques have partially solved induction motor control problems, because they are sensitive to drive parameter variations and performance may deteriorate if conventional controllers are used. Intelligent controllers are considered as potential candidates for such an application. In this paper, the performance of the various sensor less intelligent Direct Torque Control (DTC techniques of Induction motor such as neural network, fuzzy and genetic algorithm based torque controllers are evaluated. Adaptive intelligent techniques are applied to achieve high performance decoupled flux and torque control. This paper contributes: i Development of Neural network algorithm for state selection in DTC; ii Development of new algorithm for state selection using Genetic algorithm principle; and iii Development of Fuzzy based DTC. Simulations have been performed using the trained state selector neural network instead of conventional DTC and Fuzzy controller instead of conventional DTC controller. The results show agreement with those of the conventional DTC.

  12. Neural network approach to continuous-time direct adaptive optimal control for partially unknown nonlinear systems.

    Science.gov (United States)

    Vrabie, Draguna; Lewis, Frank

    2009-04-01

    In this paper we present in a continuous-time framework an online approach to direct adaptive optimal control with infinite horizon cost for nonlinear systems. The algorithm converges online to the optimal control solution without knowledge of the internal system dynamics. Closed-loop dynamic stability is guaranteed throughout. The algorithm is based on a reinforcement learning scheme, namely Policy Iterations, and makes use of neural networks, in an Actor/Critic structure, to parametrically represent the control policy and the performance of the control system. The two neural networks are trained to express the optimal controller and optimal cost function which describes the infinite horizon control performance. Convergence of the algorithm is proven under the realistic assumption that the two neural networks do not provide perfect representations for the nonlinear control and cost functions. The result is a hybrid control structure which involves a continuous-time controller and a supervisory adaptation structure which operates based on data sampled from the plant and from the continuous-time performance dynamics. Such control structure is unlike any standard form of controllers previously seen in the literature. Simulation results, obtained considering two second-order nonlinear systems, are provided. PMID:19362449

  13. Implementation of Directional Control System for Autonomous Robot Based on Voice Command Controller

    Directory of Open Access Journals (Sweden)

    Han Nilar Htay

    2014-10-01

    Full Text Available The main idea of this research is to process analog voice signal. The paper is implemented for controlling the robot by voice command. The implemented system involves voice recognition unit, digital data processing unit with DC switching section. The proposed system consists of a microcontroller and a voice recognition processor that can recognize a limited number of voice patterns. This is voice based guidance system, which uses the special voice recognition IC HM2007 for speech enhancement. It also generates different desired signals according to the spoken words which further used to control the movement of robot. The microcontroller used is PIC16F877A, to give the instructions to the robot for its operation. Backup power is included in this research to retain the voice commands while the system is powered off. The R.F transmitter and receiver are used here, for the wireless transmission purpose. The constructed system can be commanded in the voice of English as well as Myanmar.

  14. The kinematics of directional control in the fast start of zebrafish larvae.

    Science.gov (United States)

    Nair, Arjun; Azatian, Grigor; McHenry, Matthew J

    2015-12-01

    Larval fish use the 'fast start' escape response to rapidly evade the strike of a predator with a three-dimensional (3D) maneuver. Although this behavior is essential for the survival of fishes, it is not clear how its motion is controlled by the motor system of a larval fish. As a basis for understanding this control, we measured the high-speed kinematics of the body of zebrafish (Danio rerio) larvae when executing the fast start in a variety of directions. We found that the angular excursion in the lateral direction is correlated with the yaw angle in the initial stage of bending (stage 1). In this way, larvae moved in a manner similar to that reported for adult fish. However, larvae also have the ability to control the elevation of a fast start. We found that escapes directed downwards or upwards were achieved by pitching the body throughout the stages of the fast start. Changes in the pitching angle in each stage were significantly correlated with the elevation angle of the trajectory. Therefore, as a larva performs rapid oscillations in yaw that contribute to undulatory motion, the elevation of an escape is generated by more gradual and sustained changes in pitch. These observations are consistent with a model of motor control where elevation is directed through the differential activation of the epaxial and hypaxial musculature. This 3D motion could serve to enhance evasiveness by varying elevation without slowing the escape from a predator. PMID:26519511

  15. Conflicts over Directing the Education of Children: Who Controls, Parents or School Officials?

    Science.gov (United States)

    Russo, Charles J.

    2005-01-01

    When dealing with the issues of quality control and the rights of parents to direct the upbringing of their school-aged children, one of the key factors that affects parental rights is compulsory attendance laws. Put another way, insofar as parents must educate their children, whether in regular public or nonpublic schools or by homeschooling…

  16. Reducing user discomfort in direct load control of domestic water heaters

    NARCIS (Netherlands)

    Belov, Alexander; Vasenev, Alexandr; Havinga, Paul J.M.; Meratnia, Nirvana; Zwaag, van der Berend Jan

    2015-01-01

    Direct Load Control (DLC) is an effective instrument for achieving a guaranteed load curtailment. Unfortunately, if a customer considers that personal discomfort outweighs money savings after DLC shutting down of home appliances, DLC solution can be rejected. This paper proposes the way to remediate

  17. Impact of glycaemic control on the effect of direct renin inhibition in the AVOID study

    DEFF Research Database (Denmark)

    Persson, Frederik; Lewis, Julia B; Lewis, Edmund J; Rossing, Peter; Hollenberg, Norman K; Parving, Hans-Henrik

    2012-01-01

    Hyperglycaemia induces development and progression of microvascular complications in diabetes. A direct link between high glucose levels and intrarenal renin-angiotensin activation has been demonstrated. This post-hoc analysis assessed the influence of baseline glycaemic control on the reduction ...... albuminuria with aliskiren or placebo added to losartan in the Aliskiren in the EValuation of PrOteinuria In Diabetes (AVOID) study....

  18. Personalisation of Adult Social Care: Self-Directed Support and the Choice and Control Agenda

    Science.gov (United States)

    Kendall, Sophie; Cameron, Ailsa

    2014-01-01

    In 2007, "self-directed support" was introduced in adult social care in England to establish choice and control--in the assessment process itself and over service provision--for "all" service users. The personalisation agenda is underpinned by a range of ideologies, particularly a civil rights empowerment approach and…

  19. Direct Force Control of a Rudder with the Action of a Coplanar Waveguide Product Microwave

    Institute of Scientific and Technical Information of China (English)

    LIU Zong-Kai; ZHOU Ben-Mou; LIU Hui-Xing; LIU Zhi-Gang; JI Yan-Liang

    2011-01-01

    We investigate the distribution of electromagnetic body force in a fluid boundary layer produced by a coplanar waveguide (CPW) and focus on the fluid dynamic control effects of a rudder. The electromagnetic body force along the CPW direction can be created by the mutual coupling of landscape orientated electric and magnetic fields. With CPWs arranged on the rudder's surface, a direct-force-control rudder can be realized by adjusting the microwave sources. It is also found that a streamwise microwave electromagnetic body force can markedly enhance lift force and suppress rudder vibration, thus improving response time lag significantly. Furthermore, navigation stall caused by a large angle of attack can be avoided.%@@ We investigate the distribution of electromagnetic body force in a fluid boundary layer produced by a coplanar waveguide(CPW)and focus on the fluid dynamic control effects of a rudder.The electromagnetic body force along the CPW direction can be created by the mutual coupling of landscape orientated electric and magnetic fields.With CPWs arranged on the rudder's surface,a direct-force-control rudder can be realized by adjusting the microwave sources.It is also found that a streamwise microwave electromagnetic body force can markedly enhance lift force and suppress rudder vibration,thus improving response time lag significantly.Fhrthermore,navigation stall caused by a large angle of attack can be avoided.

  20. High stability vector-based direct power control for DFIG-based wind turbine

    DEFF Research Database (Denmark)

    Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

    2015-01-01

    This paper proposes an improved vector-based direct power control (DPC) strategy for the doubly-fed induction generator (DFIG)-based wind energy conversion system. Based on the small signal model, the proposed DPC improves the stability of the DFIG, and avoids the DFIG operating in the marginal...

  1. INCREASED FLEXIBILITY OF TURBO-COMPRESSORS IN NATURAL GAS TRANSMISSION THROUGH DIRECT SURGE CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    Robert J. McKee; Shane P. Siebenaler; Danny M. Deffenbaugh

    2005-02-25

    The objective of this Direct Surge Control project was to develop a new internal method to avoid surge of pipeline compressors. This method will safely expand the range and flexibility of compressor operations, while minimizing wasteful recycle flow at the lower end of the operating envelope. The approach is to sense the onset of surge with a probe that directly measures re-circulation at the impeller inlet. The signals from the probe are used by a controller to allow operation at low flow conditions without resorting to a predictive method requiring excessive margin to activate a recycle valve. The sensor developed and demonstrated during this project was a simple, rugged, and sensitive drag probe. Experiments conducted in a laboratory compressor clearly showed the effectiveness of the technique. Subsequent field demonstrations indicated that the increase in range without the need to recycle flow was on the order of 19% to 25%. The cost benefit of applying the direct surge control technology appears to be as much as $120 per hour per compressor for operation without the current level of recycle flow. This could amount to approximately $85 million per year for the U.S. Natural Gas Transmission industry, if direct surge control systems are applied to most pipeline centrifugal compressors.

  2. Tracer Gas Technique Versus a Control Box Method for Estimating Direct Capture Efficiency of Exhaust Systems

    DEFF Research Database (Denmark)

    Madsen, U.; Aubertin, G.; Breum, N. O.; Fontaine, J. R.; Nielsen, Peter V.

    Numerical modelling of direct capture efficiency of a local exhaust is used to compare the tracer gas technique of a proposed CEN standard against a more consistent approach based on an imaginary control box. It is concluded that the tracer gas technique is useful for field applications....

  3. Direct microcomputer controlled determination of zinc in human serum by flow injection atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Simonsen, Kirsten Wiese; Nielsen, Bent; Jensen, Arne;

    1986-01-01

    A procedure is described for the direct determination of zinc in human serum by fully automated, microcomputer controlled flow injection atomic absorption spectrometry (Fl-AAS). The Fl system is pumpless, using the negative pressure created by the nebuliser. It only consists of a three-way valve...

  4. Directional antenna array (DAA) for communications, control, and data link protection

    Science.gov (United States)

    Molchanov, Pavlo A.; Contarino, Vincent M.

    2013-06-01

    A next generation of Smart antennas with point-to-point communication and jam, spoof protection capability by verification of spatial position is offered. A directional antenna array (DAA) with narrow irradiation beam provides counter terrorism protection for communications, data link, control and GPS. Communications are "invisible" to guided missiles because of 20 dB smaller irradiation outside the beam and spatial separation. This solution can be implemented with current technology. Directional antennas have higher gain and can be multi-frequency or have wide frequency band in contrast to phase antenna arrays. This multi-directional antenna array provides a multi-functional communication network and simultaneously can be used for command control, data link and GPS.

  5. A simple hardware realization of switching table based direct torque control of induction motor

    Energy Technology Data Exchange (ETDEWEB)

    Panigrahi, Bibhu Prasad [Department of Electrical Engineering, Indira Gandhi Institute of Technology, Sarang, Dhenkanal, Orissa 759146 (India); Prasad, Dinkar; SenGupta, Sabyasachi [Department of Electrical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India)

    2007-02-15

    A simple hardware realization of direct torque control (DTC) scheme for fast control of induction motor torque has been presented. The proposed hardware scheme mimics the conventional switching table based DTC scheme and does not require use of any online fast computing device like microprocessor, PC or DSP. The controller uses only commonly used discrete hardware components. The experimental results of the proposed hardware implementation have been presented and supported with simulation results. Another alternate hardware scheme without using the switching table has also been proposed and the experimental results of both the schemes have been compared and found to be in agreement with each other. (author)

  6. Synthesis and design of a Cartesian observer for control variables of an induction motor direct torque control

    Energy Technology Data Exchange (ETDEWEB)

    Belhadj, J.; Slama-Belkhodja, I. [ENIT, LSE, Le Belvedere (Tunisia); Pietrzak-David, M. [INP-ENSEEIHT, LEEI, CNRS (France)

    2000-08-01

    This work focuses on the synthesis and the design of a short time calculation observer of stator flux and electromagnetic torque, for an induction motor controlled by the Direct Torque Control (DTC). We put emphasis on robustness, especially at very low speed. The reduction of time calculation is obtained by separating the symmetrical structures of the full order observer, in {alpha} and {beta} stationary axes. Discreatisation is carried out in order to obtain a digital real time implementation. Observer gain design is based on dynamic performance analysis. Simulation results are carried out to illustrate the efficiency of the developed drive. (orig.)

  7. An Optimal Control Method for Maximizing the Efficiency of Direct Drive Ocean Wave Energy Extraction System

    Directory of Open Access Journals (Sweden)

    Zhongxian Chen

    2014-01-01

    Full Text Available The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability.

  8. Direct torque control design and experimental evaluation for the brushless doubly fed machine

    Energy Technology Data Exchange (ETDEWEB)

    Sarasola, Izaskun, E-mail: isarasola@trainelec.co [Trainelec S.L., Engineering Department, Poligono Katategi., Irura 20271 (Spain); Poza, Javier, E-mail: jpoza@eps.mondragon.ed [Faculty of Engineering, University of Mondragon, Mondragon 20500 (Spain); Rodriguez, Miguel A., E-mail: miguelangel.rodriguez@ingeteam.co [Ingeteam T and D, S.A. Aptdo. 48970 Basauri (Spain); Abad, Gonzalo, E-mail: gabad@eps.mondragon.ed [Faculty of Engineering, University of Mondragon, Mondragon 20500 (Spain)

    2011-02-15

    In this paper, a direct torque control (DTC) strategy for the brushless doubly fed machine (BDFM) is presented. After analyzing the mathematical model of this machine, the voltage vectors look-up table of classical DTC techniques is derived. Then, the behavior of the machine is studied when it is controlled by the developed DTC technique, concluding that under some specific operation conditions, a BDFM could present a time interval where the torque and the flux can not be controlled simultaneously. In these cases, two different control solutions have been defined: 'flux priority' and 'torque priority'. Finally, simulation and experimental results validate the effectiveness of the proposed control algorithms.

  9. A Novel Maximum Power Point Tracking Control for Permanent Magnet Direct Drive Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2012-05-01

    Full Text Available This paper proposes a novel optimal current given (OCG maximum power point tracking (MPPT control strategy based on the theory of power feedback and hill climb searching (HCS for a permanent magnet direct drive wind energy conversion system (WECS. The presented strategy not only has the advantages of not needing the wind speed and wind turbine characteristics of the traditional HCS method, but it also improves the stability and accuracy of MPPT by estimating the exact loss torque. The OCG MPPT control strategy is first carried out by simulation, then an experimental platform based on the dSPACE1103 controller is built and a 5.5 kW permanent magnet synchronous generator (PMSG is tested. Furthermore, the proposed method is compared experimentally with the traditional optimum tip speed ratio (TSR MPPT control. The experiments verify the effectiveness of the proposed OCG MPPT strategy and demonstrate its better performance than the traditional TSR MPPT control.

  10. Robust Fuzzy-Second Order Sliding Mode based Direct Power Control for Voltage Source Converter

    Directory of Open Access Journals (Sweden)

    D. Kairous

    2015-08-01

    Full Text Available This paper focuses on a second order sliding mode based direct power controller (SOSM-DPC of a three-phase grid-connected voltage source converter (VSC. The proposed control scheme combined with fuzzy logic aims at regulating the DC-link voltage of the converter and precisely tracking arbitrary power references, in order to easily control the system’s power factor. Therefore measures are proposed to reduce the chattering effects inherent to sliding-mode control (SMC. Simulations performed under Matlab/Simulink validate the feasibility of the designed Fuzzy-SOSM. Simulation results on a 1kVA grid-connected VSC under normal and faulted grid voltage conditions demonstrate good performance of the proposed control law in terms of robustness, stability and precision.

  11. Direct battery-driven solar LED lighting using constant-power control

    KAUST Repository

    Huang, Bin-Juine

    2012-11-01

    A direct battery-driven LED lighting technique using constant-power control is proposed in the present study. A system dynamics model of LED luminaire was derived and used in the design of the feedback constant-power control system. The test result has shown that the power of 18. W and 100. W LED luminaires can be controlled accurately with error at 2-5%. A solar LED street lighting system using constant-power and dimming control was designed and built for field test in a remote area. The long-term performance was satisfactory and no any failure since the installation. Since no high-power capacitor is used in the present constant-power control circuit, a longer lifetime is expected. © 2012 Elsevier Ltd.

  12. Characterizing a psychiatric symptom dimension related to deficits in goal-directed control.

    Science.gov (United States)

    Gillan, Claire M; Kosinski, Michal; Whelan, Robert; Phelps, Elizabeth A; Daw, Nathaniel D

    2016-01-01

    Prominent theories suggest that compulsive behaviors, characteristic of obsessive-compulsive disorder and addiction, are driven by shared deficits in goal-directed control, which confers vulnerability for developing rigid habits. However, recent studies have shown that deficient goal-directed control accompanies several disorders, including those without an obvious compulsive element. Reasoning that this lack of clinical specificity might reflect broader issues with psychiatric diagnostic categories, we investigated whether a dimensional approach would better delineate the clinical manifestations of goal-directed deficits. Using large-scale online assessment of psychiatric symptoms and neurocognitive performance in two independent general-population samples, we found that deficits in goal-directed control were most strongly associated with a symptom dimension comprising compulsive behavior and intrusive thought. This association was highly specific when compared to other non-compulsive aspects of psychopathology. These data showcase a powerful new methodology and highlight the potential of a dimensional, biologically-grounded approach to psychiatry research. PMID:26928075

  13. Control performances of a piezoactuator direct drive valve system at high temperatures with thermal insulation

    Science.gov (United States)

    Han, Yung-Min; Han, Chulhee; Kim, Wan Ho; Seong, Ho Yong; Choi, Seung-Bok

    2016-09-01

    This technical note presents control performances of a piezoactuator direct drive valve (PDDV) operated at high temperature environment. After briefly discussing operating principle and mechanical dimensions of the proposed PDDV, an appropriate size of the PDDV is manufactured. As a first step, the temperature effect on the valve performance is experimentally investigated by measuring the spool displacement at various temperatures. Subsequently, the PDDV is thermally insulated using aerogel and installed in a large-size heat chamber in which the pneumatic-hydraulic cylinders and sensors are equipped. A proportional-integral-derivative feedback controller is then designed and implemented to control the spool displacement of the valve system. In this work, the spool displacement is chosen as a control variable since it is directly related to the flow rate of the valve system. Three different sinusoidal displacements with different frequencies of 1, 10 and 50 Hz are used as reference spool displacement and tracking controls are undertaken up to 150 °C. It is shown that the proposed PDDV with the thermal insulation can provide favorable control responses without significant tracking errors at high temperatures.

  14. Digital Simulation of Conventional Direct Torque Control of Induction Motor Drive with Reduced Flux and Torque Ripples.

    OpenAIRE

    Mr.P.Nagasekhar Reddy

    2013-01-01

    The induction motors are known as the workhorses of industry because of its simple construction and robustness. Traditionally, the induction motor has been used in constant and variable speed drive applications that do not cater for fast dynamic processes. Because of recent development of several new control technologies, such as vector control, sensor less control and direct torque control (DTC), the situation is changing rapidly. The Direct Torque Control (DTC) technique has the feature of ...

  15. Direct torque control of permanent magnet synchronous machines - analysis and implementation

    Energy Technology Data Exchange (ETDEWEB)

    Luukko, J.

    2000-07-01

    The direct torque control (DTC) has become an accepted vector control method beside the current vector control. The DTC was first applied to asynchronous machines, and has later been applied also to synchronous machines. This thesis analyses the application of the DTC to permanent magnet synchronous machines (PMSM). In order to take the full advantage of the DTC, the PMSM has to be properly dimensioned. Therefore the effect of the motor parameters is analysed taking the control principle into account. Based on the analysis, a parameter selection procedure is presented. The analysis and the selection procedure utilize nonlinear optimization methods. The key element of a direct torque controlled drive is the estimation of the stator flux linkage. Different estimation methods - a combination of current and voltage models and improved integration methods - are analysed. The effect of an incorrect measured rotor angle in the current model is analysed and an error detection and compensation method is presented. The dynamic performance of an earlier presented sensorless flux estimation method is made better by improving the dynamic performance of the lowpass filter used and by adapting the correction of the flux linkage to torque changes. A method for the estimation of the initial angle of the rotor is presented. The,method is based on measuring the inductance of the machine in several directions and fitting the measurements into a model. The model is nonlinear with respect to the rotor angle and therefore a nonlinear least squares optimization method is needed in the procedure. A commonly used current vector control scheme is the minimum current control. In the DTC the stator flux linkage reference is usually kept constant. Achieving the minimum current requires the control of the reference. An on-line method to perform the minimization of the current by controlling the stator flux linkage reference is presented. Also, the control of the reference above the base speed is

  16. Combined Discrete Space Voltage Vector with Direct Torque Control for Bearingless Brushless DC Motor and Closed-Loop Suspended Force Control

    OpenAIRE

    Weiran Wang; Xiaolian Wang; Fei Tan; Zhanshi Sheng

    2013-01-01

    In order to improve the performance of bearingless brushless DC motor, a closed-loop suspended force controller combining the discrete space voltage vector modulation is applied and the direct torque control is presented in this paper. Firstly, we increase the number of the control vector to reduce the torque ripple. Then, the suspending equation is constructed which is spired by the direct torque control algorithm. As a result, the closed-loop suspended force controller is built. The simulat...

  17. Incorporating a disturbance observer with direct velocity feedback for control of human-induced vibrations

    Science.gov (United States)

    Nyawako, Donald; Reynolds, Paul; Hudson, Emma

    2016-04-01

    Feedback control strategies are desirable for disturbance rejection of human-induced vibrations in civil engineering structures as human walking forces cannot easily be measured. In relation to human-induced vibration control studies, most past researches have focused on floors and footbridges and the widely used linear controller implemented in the trials has been the direct velocity feedback (DVF) scheme. With appropriate compensation to enhance its robustness, it has been shown to be effective at damping out the problematic modes of vibration of the structures in which the active vibration control systems have been implemented. The work presented here introduces a disturbance observer (DOB) that is used with an outer-loop DVF controller. Results of analytical studies presented in this work based on the dynamic properties of a walkway bridge structure demonstrate the potential of this approach for enhancing the vibration mitigation performance offered by a purely DVF controller. For example, estimates of controlled frequency response functions indicate improved attenuation of vibration around the dominant frequency of the walkway bridge structure as well as at higher resonant frequencies. Controlled responses from three synthesized walking excitation forces on a walkway bridge structure model show that the inclusion of the disturbance observer with an outer loop DVF has potential to improve on the vibration mitigation performance by about 3.5% at resonance and 6-10% off-resonance. These are realised with hard constraints being imposed on the low frequency actuator displacements.

  18. Leader-following control of multiple nonholonomic systems over directed communication graphs

    Science.gov (United States)

    Dong, Wenjie; Djapic, Vladimir

    2016-06-01

    This paper considers the leader-following control problem of multiple nonlinear systems with directed communication topology and a leader. If the state of each system is measurable, distributed state feedback controllers are proposed using neighbours' state information with the aid of Lyapunov techniques and properties of Laplacian matrix for time-invariant communication graph and time-varying communication graph. It is shown that the state of each system exponentially converges to the state of a leader. If the state of each system is not measurable, distributed observer-based output feedback control laws are proposed. As an application of the proposed results, formation control of wheeled mobile robots is studied. The simulation results show the effectiveness of the proposed results.

  19. The research on direct drives control system in the large aperture telescope

    Science.gov (United States)

    Li, Xiaoyan; Zhang, Zhenchao; Wang, Daxing

    2010-07-01

    A 30m giant telescope project, Chinese Future Giant Telescope (CFGT), has been proposed by Chinese astronomers. At present, a series of key techniques are being developed. This paper explores a method to control direct drive servo motor in giant telescope application, which is based on a segmented Surface-mounted Permanent Magnet Synchronous Motor (SMPMSM). The losses of SMPMSM and the method of reducing the losses are discussed in this paper. Phase-controlled rectification circuit is chosen to regulate rectified voltage according to the telescope status. Such design can decrease the losses of the motor to some extent. In the control system Space-vector PWM (SVPWM) algorithm acts as a control algorithm and three-phase voltage source inverter circuit acts as drive circuit. This project is subsidized by Chinese National Natural Science Funds (10833004).

  20. Power swings damping improvement by UPFC and SMES integration based on direct Lyapunov method control

    Energy Technology Data Exchange (ETDEWEB)

    Bidadfar, A.; Abedi, M.; Chu, C.C. [Tafresh Univ., Tafresh (Iran, Islamic Republic of). Dept. of Electrical Engineering; AmirKabir Univ., Tehran (Iran, Islamic Republic of). Dept. of Electrical Engineering

    2010-07-01

    An improved method of damping power swings in power systems was presented. In addition to integrating the unified power flow controller (UPFC) and superconducting magnetic energy storage (SMES), the approach also applied the direct Lyapunov method concept to determine the control scheme based on nonlinear power system model. In transient state, SMES cooperates with the UPFC converters in active power exchange. The UPFC current injection model enables the control of UPFC converters using the Lyapunov direct method. Power oscillations among power system generators decrease as a result of the energy exchanging capability of the SMES. The steady state control method is obtained to fulfill the normal task of the UPFC in the presence of SMES. The decentralizing method is used to locally control the UPFC-SMES independent of state variables of synchronous generators which require wide area measurements. PSCAD/EMTDC simulation of a typical multi-area system revealed that in addition to an improvement in power swing damping, there was a pronounced decrease of the first swing.

  1. Digital simulation and hardware implementation of a simple scheme for direct torque control of induction motor

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Dinkar; SenGupta, Sabyasachi [Department of Electrical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721 302 (India); Panigrahi, Bibhu Prasad [Department of Electrical Engineering, Indira Gandhi Institute of Technology, Sarang, Dhenkanal, Orissa 759 146 (India)

    2008-04-15

    A simple scheme that allows fast control of induction motor torque has been presented. It is different from the conventional direct torque control (DTC) scheme in the sense that it does not use the popular DTC switching table. Also, it does not require use of any online fast computing device like a microprocessor, personal computer (PC) or digital signal processor (DSP). The proposed scheme uses only commonly used discrete hardware components for its implementation. The experimental results obtained from the hardware realization of the proposed scheme are found to be in close agreement with the simulation results. (author)

  2. Digital simulation and hardware implementation of a simple scheme for direct torque control of induction motor

    International Nuclear Information System (INIS)

    A simple scheme that allows fast control of induction motor torque has been presented. It is different from the conventional direct torque control (DTC) scheme in the sense that it does not use the popular DTC switching table. Also, it does not require use of any online fast computing device like a microprocessor, personal computer (PC) or digital signal processor (DSP). The proposed scheme uses only commonly used discrete hardware components for its implementation. The experimental results obtained from the hardware realization of the proposed scheme are found to be in close agreement with the simulation results

  3. Basis Weight And Moisture Machine Direction Control System To Reduce Loss Production At Leces Paper Industry

    International Nuclear Information System (INIS)

    Basis Weight and Moisture Machine Direction Control System have been constructed by using beta absorption and infrared absorption method to reduce loss production of the paper Industry at Leces Paper Industry. Quality Paper Industry product depends on variable Basis Weight and Moisture that has been set up according to the Set Point Target Production Process with the required accuracy ± 2.5 gram/m2 for Basis Weight measurement and ± 0.1% for the moisture. The advantage of this system compared to the sample method is the effective technique of measurement and the ON-LINE control of the production process without disturbing the process production. (author)

  4. Feedback control for distributed heat transfer mechanisms in direct-contact membrane distillation system

    KAUST Repository

    Eleiwi, Fadi

    2015-09-21

    In this paper, the problem of stabilization and production rate reference tracking for a Direct-Contact Membrane Distillation (DCMD) system is addressed. Sufficient conditions for the asymptotic and exponential stabilization for DCMD system are presented using the Gronwall-Bellman lemma and Linear Matrix Inequalities (LMIs) approaches, respectively. A nonlinear observer is then proposed to estimate the temperature distribution among the DCMD domain. This contributes to propose a reference production rate control design for the DCMD process via observer-based output control approach. Finally, numerical simulations are given to show the effectiveness of the proposed methods.

  5. Controlled quantum secure direct communication using a non-symmetric quantum channel with quantum superdense coding

    International Nuclear Information System (INIS)

    We present a controlled quantum secure direct communication protocol that uses a 2-dimensional Greenberger-Horne-Zeilinger (GHZ) entangled state and a 3-dimensional Bell-basis state and employs the high-dimensional quantum superdense coding, local collective unitary operations and entanglement swapping. The proposed protocol is secure and of high source capacity. It can effectively protect the communication against a destroying-travel-qubit-type attack. With this protocol, the information transmission is greatly increased. This protocol can also be modified, so that it can be used in a multi-party control system

  6. Prediction-based ripple reduction in Direct Torque Control of an induction machine

    OpenAIRE

    Beerten, Jef; Verveckken, Jan; Driesen, Johan

    2008-01-01

    In this paper, a new prediction technique is presented in order to minimize both torque and flux ripple in direct torque control (DTC) of an induction machine. When the classical DTC scheme is implemented on a discrete-time base using a digital controller, the choice of the appropriate voltage vector is based on calculated values of torque and flux corresponding to the previous sampling moment. This time delay causes a large fraction of the overall ripple when the hysteresis bands are small c...

  7. Robust H∞directional control for a sampled-data autonomous airship

    Institute of Scientific and Technical Information of China (English)

    王曰英; 王全保; 周平方; 段登平

    2014-01-01

    A robust H∞ directional controller for a sampled-data autonomous airship with polytopic parameter uncertainties was proposed. By input delay approach, the linearized airship model was transformed into a continuous-time system with time-varying delay. Sufficient conditions were then established based on the constructed Lyapunov-Krasovskii functional, which guarantee that the system is mean-square exponentially stable with H∞performance. The desired controller can be obtained by solving the obtained conditions. Simulation results show that guaranteed minimum H∞ performance γ=1.4037 and fast response of attitude for sampled-data autonomous airship are achieved in spite of the existence of parameter uncertainties.

  8. Novel Multiparty Controlled Bidirectional Quantum Secure Direct Communication Based on Continuous-variable States

    Science.gov (United States)

    Yu, Zhen-Bo; Gong, Li-Hua; Wen, Ru-Hong

    2016-03-01

    A novel multiparty controlled bidirectional quantum secure direct communication protocol combining continuous-variable states with qubit block transmission is proposed. Two legitimate communication parties encode their own secret information into entangled optical modes with translation operations, and the secret information of each counterpart can only be recovered under the permission of all controllers. Due to continuous-variable states and block transmission strategy, the proposed protocol is easy to realize with perfect qubit efficiency. Security analyses show that the proposed protocol is free from common attacks, including the man-in-the-middle attack.

  9. A new strategy for direct torque and flux control of induction motor drives

    Energy Technology Data Exchange (ETDEWEB)

    El Moucary, C.; Mendes, E. [Laboratoire de Genie Electrique de Paris, CNRS, Gif-Sur-Yvette (France); Raithel, T.; Ortega, R. [Laboratoire des Signaux et Systemes, CNRS - Superlec, Gif-Sur- Yvette (France)

    2000-08-01

    A new Direct Torque and Flux Control (DTFC) strategy is proposed for the induction motor control. It is based on the concept of Output Regulation Subspaces (ORS) which gives a mathematical foundation to the DTFC analysis. Namely we show that the well-known Switching Table (ST), which is typically derived from physical considerations, results from applying a standard one-step-ahead switching policy to the reduced dynamics of the motor, in particular neglecting the stator resistance voltage drop. The DTFC that we propose here relies on the same principle but takes into account the full motor dynamics, hence it is reasonable to expect better dynamic responses. Similarly to the ST scheme, the proposed ORS-based strategy gives directly the states of the inverter switches. Both strategies have been implemented experimentally and the results show the superiority of the ORS-based strategy in terms of torque and flux ripple. (orig.)

  10. Classical controller design of direct drive servo valve using analytical bode method

    International Nuclear Information System (INIS)

    Direct Drive Servovalve (DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical bode method

  11. Direct measurements of controlled aerodynamic forces on a wire-suspended axisymmetric body

    Science.gov (United States)

    Abramson, Philip; Vukasinovic, Bojan; Glezer, Ari

    2011-06-01

    A novel in-line miniature force transducer is developed for direct measurements of the net aerodynamic forces and moments on a bluff body. The force transducers are integrated into each of the eight mounting wires that are utilized for suspension of an axisymmetric model in a wind tunnel having minimal wake interference. The aerodynamic forces and moments on the model are altered by induced active local attachment of the separated base flow. Fluidic control is effected by an array of four integrated aft-facing synthetic jet actuators that emanate from narrow, azimuthally segmented slots, equally distributed around the perimeter of the circular tail end. The jet orifices are embedded within a small backward-facing step that extends into a Coanda surface. The altered flow dynamics associated with both quasi-steady and transitory asymmetric activation of the flow control effect is characterized by direct force and PIV measurements.

  12. Effects of Direct Torque Control Switching Strategies on Common Voltage and Bearing Current

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Sadeghzadeh

    2012-04-01

    Full Text Available Bearing current sininduction motorsare considered a sone of the most damaging factors. Induced shaft voltage through the parasitic capacitors cause this type of current. Inthispaper,given the increasing importance of direct torque control of induction motorin industry, various switching tables are assessed in order to ensure the lowest common voltage while maintaining the performance characteristics of the drive. Finally best switching table based on the minimum CMV, less torque rippleand better quality out put reference tracking is proposed.

  13. Direct Torque Control of Sensorless Induction Machine Drives: A Two-Stage Kalman Filter Approach

    OpenAIRE

    Jinliang Zhang; Longyun Kang; Lingyu Chen; Boyu Yi; Zhihui Xu

    2015-01-01

    Extended Kalman filter (EKF) has been widely applied for sensorless direct torque control (DTC) in induction machines (IMs). One key problem associated with EKF is that the estimator suffers from computational burden and numerical problems resulting from high order mathematical models. To reduce the computational cost, a two-stage extended Kalman filter (TEKF) based solution is presented for closed-loop stator flux, speed, and torque estimation of IM to achieve sensorless DTC-SVM operations i...

  14. Short coherent control pulse with small random errors in its direction

    OpenAIRE

    Zhi-Kun, Su; Shao-Ji, Jiang

    2012-01-01

    The finite-amplitude short coherent control pulse with small random errors in its direction is considered. We derive the conditions for it to approximate an ideal delta-shaped pulse up to an error in the second order of pulse duration. Whether the symmetric and asymmetric pulse shapes would fulfill these conditions is also analyzed. The result shows that, under one of these conditions, all symmetric pulse shapes can fulfill this condition but not for all asymmetric ones..

  15. Material control study: a directed graph and fault tree procedure for adversary event set generation

    International Nuclear Information System (INIS)

    In work for the United States Nuclear Regulatory Commission, Lawrence Livermore Laboratory is developing an assessment procedure to evaluate the effectiveness of a potential nuclear facility licensee's material control (MC) system. The purpose of an MC system is to prevent the theft of special nuclear material such as plutonium and highly enriched uranium. The key in the assessment procedure is the generation and analysis of the adversary event sets by a directed graph and fault-tree methodology

  16. A Novel Maximum Power Point Tracking Control for Permanent Magnet Direct Drive Wind Energy Conversion Systems

    OpenAIRE

    Wei Wang; Ming Cheng; Ying Zhu; Wei Hua

    2012-01-01

    This paper proposes a novel optimal current given (OCG) maximum power point tracking (MPPT) control strategy based on the theory of power feedback and hill climb searching (HCS) for a permanent magnet direct drive wind energy conversion system (WECS). The presented strategy not only has the advantages of not needing the wind speed and wind turbine characteristics of the traditional HCS method, but it also improves the stability and accuracy of MPPT by estimating the exact loss torque. The OCG...

  17. Electromechanical actuator concept for the controlled and direct actuation of a hydraulic main stage

    OpenAIRE

    Ermert, Markus

    2016-01-01

    Hydraulic main stages for off highway machines have usually electromagnetic driven pilot valves. You rarely find stepper motor driven pilot systems that are directly positioning the main spool in the sectional control valve. The presented concept shows the development of an actuator in a unique setup to fulfill the requirements of most off- highway applications. Precise positioning, strength, speed and fail safe requirements were the main goals of the concept. The concept has a two phase BLDC...

  18. p53-directed translational control can shape and expand the universe of p53 target genes

    OpenAIRE

    Zaccara, S; Tebaldi, T; Pederiva, C; Ciribilli, Y; Bisio, A.; Inga, A

    2014-01-01

    The increasing number of genome-wide transcriptome analyses focusing on p53-induced cellular responses in many cellular contexts keeps adding to the already numerous p53-regulated transcriptional networks. To investigate post-transcriptional controls as an additional dimension of p53-directed gene expression responses, we performed a translatome analysis through polysomal profiling on MCF7 cells upon 16 hours of doxorubicin or nutlin-3a treatment. The comparison between the transcriptome and ...

  19. A Robust Sensorless Direct Torque Control of Induction Motor Based on MRAS and Extended Kalman Filter

    OpenAIRE

    Mustapha MESSAOUDI; Habib KRAIEM; Mouna BEN HAMED; Lassaad SBITA; Abdelkrim, Mohamed Naceur

    2008-01-01

    In this paper, the classical Direct Torque Control (DTC) of Induction Motor (IM) using an open loop pure integration suffers from the well-known problems of integration especially in the low speed operation range is detailed. To tackle this problem, the IM variables and parameters estimation is performed using a recursive non-linear observer known as EKF. This observer is used to estimate the stator currents, the rotor flux linkages, the rotor speed and the stator resistance. The main drawbac...

  20. Single-stage vibratory gyroscope control methods for direct angle measurements

    International Nuclear Information System (INIS)

    This paper presents a control algorithm that can compensate for imperfect dynamics of vibrating gyroscopes. The compensated gyroscope dynamics can directly measure the rotation angle without integrating the angular rate. The direct angle measurement approach is promising because it is exempt from the error accumulation problem. However, using control methods to compensate for imperfect dynamics for the direct angle measurement is very challenging work, and very few control algorithms were reported to achieve that. Different from existing approaches, the proposed method has the following advantages: it requires the measurements of either the proof mass velocity or position, it does not require a calibration phase prior to normal use, and it compensates different types of imperfection even when the proof mass of a gyroscope is unknown. In a demonstration case, imperfections cause system parameters 20% deviated from their designated values; the measured signals are the proof mass velocities and contaminated by zero-mean white noise with a noise level of 0.1% full scale output (FSO); the angular rate to be measured is 200sin (2π × 10t) deg s−1. The proposed algorithm can compensate for those imperfections and achieve an angle measurement accuracy of 0.23deg

  1. Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System

    Directory of Open Access Journals (Sweden)

    Xiang Cai

    2016-01-01

    Full Text Available To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV was utilized for injecting chemicals, driven by a pulse-width modulation (PWM signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input–output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy.

  2. Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System.

    Science.gov (United States)

    Cai, Xiang; Walgenbach, Martin; Doerpmond, Malte; Schulze Lammers, Peter; Sun, Yurui

    2016-01-01

    To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV) was utilized for injecting chemicals, driven by a pulse-width modulation (PWM) signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID) method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input-output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy. PMID:26805833

  3. Influence of Control Structures and Load Parameters on Performance of a Pseudo Direct Drive

    Directory of Open Access Journals (Sweden)

    Mohammed Bouheraoua

    2014-07-01

    Full Text Available The paper describes an in-depth and systematic analysis of a pseudo direct drive permanent magnet machine in closed loop control. Due to the torque being transmitted from the high-speed rotor (HSR to the low-speed rotor (LSR, through a relatively low stiffness magnetic gear with non-linear characteristics, speed oscillations appear in the drive output with a conventional proportional integral (PI controller. Therefore two candidate controllers have been proposed as an alternative to the PI control and all controllers have been optimally tuned with a genetic algorithm against a defined criterion. Furthermore, closed loop models are established in the complex frequency domain to determine the system damping and the cause of the oscillations. Consequently, the best controller structure that improves the dynamic behaviour of the system in terms of speed tracking and disturbance rejection could be identified, based on the frequency domain analysis. Experimental results are presented to validate the analysis and the proposed control technique.

  4. Method of optimizing man-machine interaction in direct digital control systems for NPPs

    International Nuclear Information System (INIS)

    A method is put forward for optimizing the man-machine interaction in direct digital control systems in NPPs. The method can be used during operation, and also to produce man-machine control systems for NPPs with optimum interaction and division of functions between the human operator and the control system. The main factors in optimizing the operation of NPPs are quality and accuracy of control in both dynamic and steady state regimes, reliable functioning of systems, and adaptation of the actions of the co-ordinating link to control aims. When regulating parameters, the human operator in an NPP by virtue of his natural adaptivity comes to a compromise between exact regulation and expenditure on control. In the light of the above, a criterion for optimum systems functioning is put forward. We propose the use of mimic systems to optimize control in line with this criterion since these systems permit a comprehensive solution to problems and reproduce natural operating conditions. (author). 2 refs, 4 figs

  5. Directional hydraulic fracturing to control hard-roof rockburst in coal mines

    Institute of Scientific and Technical Information of China (English)

    Fan Jun; Dou Linming; He Hu; Du Taotao; Zhang Shibin; Gui Bing; Sun Xinglin

    2012-01-01

    Hard roof is the main factor that induces rock-burst.In view of the present obvious weakness of control measures for hard roof rockburst in domestic collieries,the mechanism and field application of directional hydraulic fracturing technology for rock-burst prevention have been investigated in this paper using theoretical analysis and numerical simulation.The results show that the weighting span of the main roof and the released kinetic energy as well as the total elastic energy decreased greatly after the directional fracturing of hard roof with the mining progression,thereby reducing the rockburst hazard degree to coal body.The directional hydraulic fracturing technology was carried out in 6305 working face of Jisan Coal Mine to prevent rockburst.Field practices have proved that this technology is much simpler and safer to operate with better prevention effect compared with blasting.By optimizing the operation procedures and developing a new technology of automated high-pressure delivery pipe,the maximum fracturing radius now reaches more than 9 m and the borehole depth exceeds 20 m.Additionally,drilling cutting method was applied to monitor the stress of the coal mass before and after the fracturing,and the drill cuttings dropped significantly which indicates that the burst prevention effect of directional hydraulic fracturing technology is very remarkable.The research results of this paper have laid a theoretical and practical foundation for the widespread application of the directional hydraulic fracturing technology in China.

  6. A Novel Direct Torque Control Permanent Magnet Synchronous Motor Drive used in Electrical Vehicle

    Directory of Open Access Journals (Sweden)

    Yaohua Li

    2011-10-01

    Full Text Available In this paper, a modified direct torque control (DTC scheme for permanent magnet synchronous motor (PMSM is investigated, which enables low torque ripple by using an improved voltage vector selection strategy instead of switching table used in conventional DTC. Based on the control of stator flux, torque angle and torque, voltage vector selection strategy of PMSM DTC drive is proposed. In the proposed voltage vector selection strategy, the applied voltage vector is determined according to outputs of hysteresis comparators for stator flux and torque, angular position of stator flux and torque angle, which is finally synthesized by space vector modulation (SVM. Modeling and experimental results for an interior PMSM used in Honda Civic 06My Hybrid electrical vehicle are given. Simulation and experimental results show torque ripple is reduced and the total harmonics of stator current is decreased when compared those of conventional DTC. And a fixed switching frequency is obtained with the help of SVM. In addition, the proposed DTC doesn’t need any additional PI controller, which maintains the simplicity in conventional DTC. Keywords: direct torque control, permanent magnet synchronous motor, electrical vehicle, torque ripple, switching frequency

  7. Improved direct torque control for induction motor drives with rapid prototyping system

    International Nuclear Information System (INIS)

    Direct torque control is an AC drives control method especially designed to provide fast and robust responses, but they usually behave like hysteresis controllers. Consequently, there are similar problems like non-constant switching frequencies and high torque ripple, especially when operation conditions result in low switching frequencies. In this paper, the basic concept of DTC will be improved by modifying the classical method. Problems that arise when using standard DTC methods are explained, and improvements are derived to overcome these problems. Two theoretical approaches are verified and compared with standard DTC by measurements and experiments. The proposed methods provide a constant switching frequency and solve the starting problem without dither signal. Further results are a reduction of torque pulsations as well as a new method for stator flux estimation. Experimental results of the new DTC method obtained by an experimental rapid prototype system for drives are presented

  8. Improved direct torque control for induction motor drives with rapid prototyping system

    Energy Technology Data Exchange (ETDEWEB)

    Kennel, Ralph [Electrical Machines and Drives, Wuppertal University, D-42097 Wuppertal, Wuppertal (Germany); El-kholy, Elwy E. [Electrical Engineering Departement, Faculty of Engineering, Menoufiya University, Shebin El-kom (Egypt)]. E-mail: eelkholy@yahoo.com; Mahmoud, Sabry [Electrical Engineering Departement, Faculty of Engineering, Menoufiya University, Shebin El-kom (Egypt); El-refaei, Abdou [Electrical Technology Departement, Industrial College (IEC), Cairo (Egypt); Elkady, Farouk [Electrical Technology Departement, Industrial College (IEC), Cairo (Egypt)

    2006-08-15

    Direct torque control is an AC drives control method especially designed to provide fast and robust responses, but they usually behave like hysteresis controllers. Consequently, there are similar problems like non-constant switching frequencies and high torque ripple, especially when operation conditions result in low switching frequencies. In this paper, the basic concept of DTC will be improved by modifying the classical method. Problems that arise when using standard DTC methods are explained, and improvements are derived to overcome these problems. Two theoretical approaches are verified and compared with standard DTC by measurements and experiments. The proposed methods provide a constant switching frequency and solve the starting problem without dither signal. Further results are a reduction of torque pulsations as well as a new method for stator flux estimation. Experimental results of the new DTC method obtained by an experimental rapid prototype system for drives are presented.

  9. Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines

    Science.gov (United States)

    Kenny, Barbara H.; Lorenz, Robert D.

    2003-01-01

    A new, deadbeat type of direct torque control is proposed, analyzed and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

  10. Electromagnetic torque signal estimation in a direct torque control system for electrical machines

    Energy Technology Data Exchange (ETDEWEB)

    Orille, A.L. [Polytechnic Univ. of Catalonia, Dept. of Electrical Engineering, Barcelona (Spain); Sowilam, G.M.A. [Helwan Univ., Dept. of Electrical Engineering, Barcelona (Spain); Villada Duque, F. [Univ. of Antioquia, Dept. of Electrical Engineering, Barcelona (Spain)

    2000-08-01

    Recently, the emerging technology of artificial neural networks (ANNs) has been successfully used in a variety of applications in industrial control. This work proposes the use of multilayer neural networks for the estimation of the electromagnetic torque signal in a direct torque control system (DTC). The simulation of the DTC complete system, including the induction motor, the power electronics supply system, and the control unit, is developed using the program SIMULINK of Matlab. Once selected the right structure of the neural network, on-line testing is realised as a part of the DTC system to determinate its stability and liability. The performance of the system including the neural network for the estimation of the electromagnetic torque signal is compared with the simulation of the system without using neural networks. (orig.)

  11. Direct Torque Control of a Synchronous Reluctance Motor Using the Finite Element Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Moon Ju; Kim, Sol; Lee, Ju [Dept. of Electrical Eng., Hanyang University, Seoul (Korea); Ko, Kwon Min; Kim, Tea Duk; Oh, Sang Kyeong [Samsung Electronics (Korea)

    2002-07-01

    Reluctance torque is generated by the rotor of the rugged construction is Synchronous Reluctance Motor. Its construction is simple, and it is very economic because a rotor in existed AC motor can be used. As the Synchronous inductance in Synchronous Reluctance Motor is an element that is proportional to torque, the exact value must be experimentally or analytically found for controlling and the performance development of motors. In this paper, direct torque control simulation to maximize the torque of the Synchronous Reluctance Motor and fast response characteristics was carried out with the inductance value by the Finite Element Method. For the simulation results, There are torques and fluxs response characteristics when controlling speed. (author). 7 refs., 10 figs., 2 tabs.

  12. Stereotype for direction-of-movement of the controls associated with some displays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Chul; Lee, Jung Woon; Lee, Yong Hee; Oh, Un Seok; Cha, Woo Chang

    2002-05-01

    The human factor design guideline which has been developed for Ulchin Nuclear Units 3 and 4, HF010, refers mainly to NUREG-0700 which was based on American operators' behaviors. It is very important to develop the design guidelines which can be applicable for Korean operators for the purpose of designing the Korean Standard Nuclear Power plant more safely. The objective of this project is to provide the standards, guidelines and bases applicable for HF010 through the within-subject experiment for obtaining Korean operators' population stereotype for direction-of-movement of the KSNP controls associated with the displays. The scope and contents of this project includes the taxonomy of displays/controls types in KSNP MCR, development of the facilitating system for stereotype experiment, survey of the researches on display compatibility and experiment for obtaining population stereotype of control movement.

  13. Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines. Revision 1

    Science.gov (United States)

    Kenny, Barbara H.; Lorenz, Robert D.

    2002-01-01

    A new, deadbeat type of direct torque control is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

  14. Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines

    Science.gov (United States)

    Kenny, Barbara H.; Lorenz, Robert D.

    2001-01-01

    A new, deadbeat type of direct torque control is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

  15. Stereotype for direction-of-movement of the controls associated with some displays

    International Nuclear Information System (INIS)

    The human factor design guideline which has been developed for Ulchin Nuclear Units 3 and 4, HF010, refers mainly to NUREG-0700 which was based on American operators' behaviors. It is very important to develop the design guidelines which can be applicable for Korean operators for the purpose of designing the Korean Standard Nuclear Power plant more safely. The objective of this project is to provide the standards, guidelines and bases applicable for HF010 through the within-subject experiment for obtaining Korean operators' population stereotype for direction-of-movement of the KSNP controls associated with the displays. The scope and contents of this project includes the taxonomy of displays/controls types in KSNP MCR, development of the facilitating system for stereotype experiment, survey of the researches on display compatibility and experiment for obtaining population stereotype of control movement

  16. [Community health workers' knowledge on tuberculosis, control measures, and directly observed therapy].

    Science.gov (United States)

    Rocha, Gustavo Silva Souto; Lima, Marina Guimaraes; Moreira, Joyce Laura; Ribeiro, Kennedy Crepalde; Ceccato, Maria das Graças Braga; Carvalho, Wânia da Silva; Silveira, Micheline Rosa

    2015-07-01

    This study assessed community health workers' (CHW) knowledge on tuberculosis (TB), TB control measures, and directly observed therapy (DOT) in Belo Horizonte, Minas Gerais State, Brazil. This was a cross-sectional study that applied a questionnaire in a random and representative sample of 489 CHW. The overall proportion of correct answers was 74.6%. The mean proportions of correct answers in the domains for TB, TB control measures, and DOT were 81%, 84.1%, and 59.4%, respectively. The study showed knowledge gaps in the identification of patients with pulmonary TB, the target public for DOT, and adequate technique for treatment supervision. Better knowledge was associated with time working as a CHW (OR = 2.3) and follow-up of cases in the 12 months prior to the interview (OR = 1.7). The study provided new scientific data on level of knowledge among CHW concerning DOT and can support strategies to improve TB control activities. PMID:26248103

  17. Direct control of perennial weeds between crops - Implication for organic farming

    DEFF Research Database (Denmark)

    Melander, Bo; Holst, Niels; Rasmussen, Ilse Ankjær;

    2012-01-01

    Perennial weeds can be a major constraint to organic crop production and direct control actions applied between crops can then be necessary to reduce the problems. We conducted two experiments, one on a sandy loam and one on a sandy soil in Denmark, with the aim of studying the efficacy of...... ending the strategy with mouldboard ploughing in the succeeding spring. Grain yields did not differ among the treatments in the two experiments as a result of the generally high effectiveness exerted by the control strategies. Especially post-harvest control strategies based on rotating weed devices and...... mouldboard ploughing appear to be effective solutions against mixed stands of perennials on sandy soils but they do not comply with optimal nutrient management in organic cropping. Therefore, intensive autumn cultivation is only relevant where a perennial weed problem is uncontrollable by other means....

  18. Direct Torque Control for Three-Level Neutral Point Clamped Inverter-Fed Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    M. K. Sahu

    2012-04-01

    Full Text Available Direct torque control (DTC is a control technique in AC drive systems to obtain high performance torque control. The classical DTC drive contains a pair of hysteresis comparators and suffers from variable switching frequency and high torque ripple. These problems can be solved by using space vector depending on the reference torque and flux. In this paper the space vector modulation technique is applied to the three-level Neutral Point Clamped (NPC inverter control in the proposed DTC-based induction motor drive system, resulting to a significant reduce of torque ripple. Three-level neutral point clamped inverters have been widely used in medium voltage applications. This type of inverters have several advantages over standard two-level VSI, such as greater number of levels in the output voltage waveforms, less harmonic distortion in voltage and current waveforms and lower switching frequencies. This paper emphasizes the derivation of switching states using the Space Vector Pulse Width Modulation (SVPWM technique. The control scheme is implemented using Matlab/Simulink. Experimental results using dSPACE validate the steady-state and the dynamic performance of the proposed control strategy.

  19. Direct Lyapunov-based control law design for spacecraft attitude maneuvers

    Institute of Scientific and Technical Information of China (English)

    HU Likun; ANG Qingchao

    2006-01-01

    A direct Lyapunov-based control law is presented to perform on-orbit stability for spacecraft attitude maneuvers. Spacecraft attitude kinematic equations and dynamic equations are coupled, nonlinear, multi-input multi-output(MIMO), which baffles controller design. Orbit angular rates are taken into account in kinematic equations and influence of gravity gradient moments and disturbance moments on the spacecraft attitude in dynamic equations is considered to approach the practical environment, which enhance the problem complexity to some extent. Based on attitude tracking errors and angular rates, a Lyapunov function is constructed, through which the stabilizing feedback control law is deduced via Lie derivation of the Lyapunov function. The proposed method can deal with the case that the spacecraft is subjected to mass property variations or centroidal inertia matrix variations due to fuel assumption or flexibility, and disturbance moments, which shows the proposed controller is robust for spacecraft attitude maneuvers. The unlimited controller and the limited controller are taken into account respectively in simulations. Simulation results are demonstrated to validate effectiveness and feasibility of the proposed method.

  20. Direct and indirect spino-cerebellar pathways: shared ideas but different functions in motor control

    Directory of Open Access Journals (Sweden)

    Juan eJiang

    2015-07-01

    Full Text Available The impressive precision of mammalian limb movements relies on internal feedback pathways that convey information about ongoing motor output to cerebellar circuits. The spino-cerebellar tracts (SCT in the cervical, thoracic and lumbar spinal cord have long been considered canonical neural substrates for the conveyance of internal feedback signals. Here we consider the distinct features of an indirect spino-cerebellar route, via the brainstem lateral reticular nucleus (LRN, and the implications of this pre-cerebellar ‘detour’ for the execution and evolution of limb motor control. Both direct and indirect spino-cerebellar pathways signal spinal interneuronal activity to the cerebellum during movements, but evidence suggests that direct SCT neurons are mainly modulated by rhythmic activity, whereas the LRN also receives information from systems active during postural adjustment, reaching and grasping. Thus, while direct and indirect spino-cerebellar circuits can both be regarded as internal copy pathways, it seems likely that the direct system is principally dedicated to rhythmic motor acts like locomotion, while the indirect system also provides a means of pre-cerebellar integration relevant to the execution and coordination of de

  1. Better well control through safe drilling margin identification, influx analysis and direct bottom hole pressure control method for deep water

    Energy Technology Data Exchange (ETDEWEB)

    Veeningen, Daan [National Oilwell Varco IntelliServ (NOV), Houston, TX (United States)

    2012-07-01

    Currently, well control events are almost exclusively detected by using surface measurements. Measuring a volume increase in the 'closed loop' mud circulation system; a standpipe pressure decrease; or changes in a variety of drilling parameters provide indicators of a kick. Especially in deep water, where the riser comprises a substantial section of the well bore, early kick detection is paramount for limiting the severity of a well bore influx and improve the ability to regain well control. While downhole data is presently available from downhole tools nearby the bit, available data rates are sparse as mud pulse telemetry bandwidth is limited and well bore measurements compete with transmission of other subsurface data. Further, data transfer is one-directional, latency is significant and conditions along the string are unknown. High-bandwidth downhole data transmission system, via a wired or networked drill string system, has the unique capability to acquire real-time pressure and temperature measurement at a number of locations along the drill string. This system provides high-resolution downhole data available at very high speed, eliminating latency and restrictions that typically limit the availability of downhole data. The paper describes well control opportunities for deep water operations through the use of downhole data independent from surface measurements. First, the networked drill string provides efficient ways to identify pore pressure, fracture gradient, and true mud weight that comprise the safe drilling margin. Second, the independent measurement capability provides early kick detection and improved ability to analyze an influx even with a heterogeneous mud column through distributed along-string annular pressure measurements. Third, a methodology is proposed for a direct measurement method using downhole real-time pressure for maintaining constant bottom hole pressure during well kills in deep water. (author)

  2. Global adaptive stabilisation for nonlinear systems with unknown control directions and input disturbance

    Science.gov (United States)

    Man, Yongchao; Liu, Yungang

    2016-05-01

    This paper addresses the global adaptive stabilisation via switching and learning strategies for a class of uncertain nonlinear systems. Remarkably, the systems in question simultaneously have unknown control directions, unknown input disturbance and unknown growth rate, which makes the problem in question challenging to solve and essentially different from those in the existing literature. To solve the problem, an adaptive scheme via switching and learning is proposed by skilfully integrating the techniques of backstepping design, adaptive learning and adaptive switching. One key point in the design scheme is the introduction of the learning mechanism, in order to compensate the unknown input disturbance, and the other one is the design of the switching mechanism, through tuning the design parameters online to deal with the unknown control directions, unknown bound and period of input disturbance and unknown growth rate. The designed controller guarantees that all the signals of the resulting closed-loop systems are bounded, and furthermore, the closed-loop system states globally converge to zero.

  3. Hydrodynamic directional control of liquid metal droplets within a microfluidic flow focusing system

    Science.gov (United States)

    Gol, Berrak; Kurdzinski, Michael E.; Tovar-Lopez, Francisco J.; Petersen, Phred; Mitchell, Arnan; Khoshmanesh, Khashayar

    2016-04-01

    Here, we investigate the directional control of Galinstan liquid metal droplets when transferring from the high-viscosity glycerol core into the parallel low-viscosity NaOH sheath streams within a flow focusing microfluidic system. In the presence of sufficient flow mismatch between the sheath streams, the droplets are driven toward the higher velocity interface and cross the interface under the influence of surface tension gradient. A minimum flow mismatch of 125 μl/min is required to enable the continuous transfer of droplets toward the desired sheath stream. The response time of droplets, the time required to change the direction of droplet transfer, is governed by the response time of the syringe pump driven microfluidic system and is found to be 3.3 and 8.8 s when increasing and decreasing the flow rate of sheath stream, respectively.

  4. Controllable assembly of silver nanoparticles induced by femtosecond laser direct writing

    Science.gov (United States)

    Wang, Huan; Liu, Sen; Zhang, Yong-Lai; Wang, Jian-Nan; Wang, Lei; Xia, Hong; Chen, Qi-Dai; Ding, Hong; Sun, Hong-Bo

    2015-04-01

    We report controllable assembly of silver nanoparticles (Ag NPs) for patterning of silver microstructures. The assembly is induced by femtosecond laser direct writing (FsLDW). A tightly focused femtosecond laser beam is capable of trapping and driving Ag NPs to form desired micropatterns with a high resolution of ∼190 nm. Taking advantage of the ‘direct writing’ feature, three microelectrodes have been integrated with a microfluidic chip; two silver-based microdevices including a microheater and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices.

  5. Bent silica nanosheets directed from crystalline templates controlled by proton donors

    International Nuclear Information System (INIS)

    Linear poly(ethyleneimine) (LPEI) is easily crystallizable with the formation of various morphologies in the aqueous medium when its hot solution cooled down to room temperature. Herein, we prepared a series of crystalline precipitates of LPEI grown in the presence of proton donating compounds such as Tris–HCl, tartaric acid, amino acids, and used the precipitates in directing silica deposition. Since the proton donating compounds can mediate the pH with donating the proton to LPEI, the crystallization of LPEI evidently depended on the concentrations of the proton donating compounds. It was found that the precipitates grown in the conditions of the pH ranged 8.2–8.5 directed well-controlled bent nanosheet of silica/LPEI composites. The bent nanosheet is constructed by multi-layered structures with a little slippage between layers. The bent nanosheet silica has slit-like pore with ca. 10 nm width.

  6. Distributed Cooperative Optimal Control for Multiagent Systems on Directed Graphs: An Inverse Optimal Approach.

    Science.gov (United States)

    Zhang, Huaguang; Feng, Tao; Yang, Guang-Hong; Liang, Hongjing

    2015-07-01

    In this paper, the inverse optimal approach is employed to design distributed consensus protocols that guarantee consensus and global optimality with respect to some quadratic performance indexes for identical linear systems on a directed graph. The inverse optimal theory is developed by introducing the notion of partial stability. As a result, the necessary and sufficient conditions for inverse optimality are proposed. By means of the developed inverse optimal theory, the necessary and sufficient conditions are established for globally optimal cooperative control problems on directed graphs. Basic optimal cooperative design procedures are given based on asymptotic properties of the resulting optimal distributed consensus protocols, and the multiagent systems can reach desired consensus performance (convergence rate and damping rate) asymptotically. Finally, two examples are given to illustrate the effectiveness of the proposed methods. PMID:25216491

  7. Development of direct digital reactivity computer system (DDRCS) for dynamic control rod reactivity measurement(DCRM)

    Energy Technology Data Exchange (ETDEWEB)

    Woo, I. T.; Ryu, S. J.; Sin, H. C.; Lee, E. K.; Bae, S. M.; Lee, C. S. [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

    2002-10-01

    Neutron Flux level may be rapidly decreased to 1/100{approx}1/1000th order of magnitude during DCRM(Dynamic Control rod Reactivity Measurement) test. Because the conventional DRCS(Digital Reactivity Computer System) converts NIS current signal to analog one with the range from 0 to 2 volt, and computes reactivity, the DRCS can not measure the widely changed flux level during DCRM test. The DDRCS(Direct Digital Reactivity Computer System) which is developed in this study can measure the current of all the range directly and reduce the burden to maintain the equipments, because of its simplified structure. The function of DDRCS was fully validated through three times of plant low power physics tests. The software program to handle all the items of low power physics test will be developed.

  8. DILEMMAS OF COMMUNITY-DIRECTED MASS DRUG ADMINISTRATION FOR LYMPHATIC FILARIASIS CONTROL

    DEFF Research Database (Denmark)

    Kisoka, William; Mushi, Declare; Meyrowitsch, Dan W.;

    2016-01-01

    transmission. The qualitative research presented here followed the implementation of mass drug administration in Lindi and Morogoro Regions, Tanzania, in 2011 to understand the different forms of involvement in the campaign and the experiences of stakeholders of their part in community-directed distribution......There has in recent years been a growing interest in the social significance of global health policy and associated interventions. This paper is concerned with neglected tropical disease control, which prescribes annual mass drug administration to interrupt transmission of, among others, lymphatic...... filariasis. In Tanzania, this intervention is conducted through community-directed distribution, which aims to improve drug uptake by promoting community participation and local ownership in the intervention. However, the average uptake of drugs often remains too low to achieve the intended interruption of...

  9. Simulation and Test Study on Direct Force Control for Permanent Magnet Linear Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Haixing Wang

    2013-03-01

    Full Text Available Permanent magnet linear synchronous motor (PMLSM, which has the advantages of simple structure, small volume, high force, is a research focus and difficulties because of the thrust ripple and control problems for PMLSM. In this paper, in order to reduce thrust ripple and improve system control performance, the space voltage vector pulse width modulation technology (SVPWM was introduced into the directing force control (DFC strategy of PMLSM. In the running process, the temperature of PMLSM will rise, which changes the resistance of the primary winding. Full consideration of the change of the resistance in the motor running process, the error between the flux observed value and the actual value was analyzed. And then a new flux dynamic compensation algorithm based on flux dynamic compensation was proposed. The novel dynamic compensator was built to improve the observation accuracy of the primary flux, which solved effectively the wrong voltage vector choice and the system control performance failure due to the error of the primary flux. The Simulation and test results show that the PMLSM DFC based on SVPWM and the flux dynamic compensation has better control performance.

  10. Weed control by direct injection of plant protection products according to specific situations

    Directory of Open Access Journals (Sweden)

    Krebs, Mathias

    2016-02-01

    Full Text Available Precision Farming in agriculture allows a site-specific management of the crop. The aim of plant protection is to apply plant protection products (PPP according to the site specific requirements on the field. Within the context of a research program to promote innovation, a sprayer with direct injection of plant protection products was developed. The direct injection offers site specific spraying of different individual PPP in a single pass. The sprayer prototype is equipped with a special spray boom combining three nozzle lines. In order to prevent delay times, the nozzle lines are preloaded before spraying. First results for weed control from test stand measurements and field trials showed that the injection pumps work with high accuracy. The prototype can be used without delay times site specific with up to three different herbicides. Field trials for site-specific weed control in winter wheat demonstrate the applicability of the system under practical conditions. By treatment of subareas herbicides and therefore costs could be saved. A reduction in yield compared with the conventionally treated field areas could not be ascertained. Also an efficacy reduction through washout of active ingredient from target surfaces due to simultaneous use of all three nozzle lines with up to 1050 l/ha application rate could not be detected. At high water spray rates, the efficacy effect occurs delayed. Overall, the newly developed direct injection system proved fieldabillity during the first tests. So weed control can be carried out situation-responsive, which can save herbicides and environmental impacts are reduced.

  11. Theory study on a photonic-assisted radio frequency phase shifter with direct current voltage control

    International Nuclear Information System (INIS)

    A photonic-assisted radio frequency phase shifter with direct current voltage control is proposed using a polymer-based integrated Mach—Zehnder modulator. A closed-form expression of radio frequency (RF) signal power and phase is given. Theoretical calculation reveals that by carefully setting the bias voltages, RF signal power variation lower than 1-dB and phase accuracy less than 3° can be achieved and are not degraded by perturbation of modulation index once the bias voltage drift is kept within −3% ∼ 3%. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  12. New prospects in direct, inverse and control problems for evolution equations

    CERN Document Server

    Fragnelli, Genni; Mininni, Rosa

    2014-01-01

    This book, based on a selection of talks given at a dedicated meeting in Cortona, Italy, in June 2013, shows the high degree of interaction between a number of fields related to applied sciences. Applied sciences consider situations in which the evolution of a given system over time is observed, and the related models can be formulated in terms of evolution equations (EEs). These equations have been studied intensively in theoretical research and are the source of an enormous number of applications. In this volume, particular attention is given to direct, inverse and control problems for EEs. The book provides an updated overview of the field, revealing its richness and vitality.

  13. Direct fiber excitation with a digitally controlled solid state laser source

    CERN Document Server

    Bruning, Robert; Duparre, Michael; Forbes, Andrew

    2014-01-01

    Mode division multiplexing has been mooted as a future technology to address the impending data crunch of existing fiber networks. Present demonstrations delineate the light source from the mode creation steps, potentially inhibiting integrated solutions. Here we demonstrate an integrated mode generating source in the form of a digitally controlled solid state laser with an intra-cavity spatial light modulator. In our proof-of-principle experiment we create fiber modes on demand and couple them directly into a few-mode fiber, where after transmission they are decoupled by modal decomposition. This is the first demonstration of a single source for encoding information into the spatial modes of light.

  14. Feasibility of optimizing trimetazidine dihydrochloride release from controlled porosity osmotic pump tablets of directly compressed cores

    OpenAIRE

    Habib, Basant A.; Randa T. Abd El Rehim; Nour, Samia A.

    2013-01-01

    The aim of this study was to develop and optimize Trimetazidine dihydrochloride (TM) controlled porosity osmotic pump (CPOP) tablets of directly compressed cores. A 23 full factorial design was used to study the influence of three factors namely: PEG400 (10% and 25% based on coating polymer weight), coating level (10% and 20% of tablet core weight) and hole diameter (0 “no hole” and 1 mm). Other variables such as tablet cores, coating mixture of ethylcellulose (4%) and dibutylphthalate (2%) i...

  15. Fault-tolerant controlled quantum secure direct communication over a collective quantum noise channel

    International Nuclear Information System (INIS)

    This work proposes controlled quantum secure direct communication (CQSDC) over an ideal channel. Based on the proposed CQSDC, two fault-tolerant CQSDC protocols that are robust under two kinds of collective noises, collective-dephasing noise and collective-rotation noise, respectively, are constructed. Due to the use of quantum entanglement of the Bell state (or logical Bell state) as well as dense coding, the proposed protocols provide easier implementation as well as better qubit efficiency than other CQSDC protocols. Furthermore, the proposed protocols are also free from correlation-elicitation attack and other well-known attacks. (paper)

  16. Controllable directive radiation of a magnetic dipole above planar metal surface

    CERN Document Server

    Xi, Zheng; Yao, Peijun; Yu, Wenhai; Wang, Pei; Ming, Hai

    2013-01-01

    We report unidirectional radiation of a magnetic dipole above planar metal surface, the radiation direction can be manipulated via changing the distance between the dipole and the surface. This phenomenon is unique for the combination of magnetic dipole and metal surface and does not happen for linear polarized dipole on metal surface or magnetic dipole on dielectric surface. The underlining physics is analytically disclosed by the interference of two orthogonally-oriented dipole component with \\pi/2 phase lag. A substantially different mechanism of introducing the vectorial nature of the dipole itself to control light emission distinguishes the present scheme from nanoantenna and provides a new degree of freedom in light emission engineering.

  17. Multi-terminal direct-current grids modeling, analysis, and control

    CERN Document Server

    Chaudhuri, Nilanjan; Majumder, Rajat; Yazdani, Amirnaser

    2014-01-01

    A comprehensive modeling, analysis, and control design framework for multi-terminal direct current (MTDC) grids is presented together with their interaction with the surrounding AC networks and the impact on overall stability. The first book of its kind on the topic of multi-terminal DC (MTDC) grids  Presents a comprehensive modeling framework for MTDC grids which is compatible with the standard AC system modeling for stability studies Includes modal analysis and study of the interactions between the MTDC grid and the surrounding AC systems Addresses the problems of autonomous power sharing an

  18. A Multiparty Controlled Bidirectional Quantum Secure Direct Communication and Authentication Protocol Based on EPR Pairs

    Science.gov (United States)

    Chang, Yan; Zhang, Shi-Bin; Yan, Li-Li; Sheng, Zhi-Wei

    2013-06-01

    A multiparty controlled bidirectional quantum secure direct communication and authentication protocol is proposed based on EPR pair and entanglement swapping. The legitimate identities of communicating parties are encoded to Bell states which act as a detection sequence. Secret messages are transmitted by using the classical XOR operation, which serves as a one-time-pad. No photon with secret information transmits in the quantum channel. Compared with the protocols proposed by Wang et al. [Acta Phys. Sin. 56 (2007) 673; Opt. Commun. 266 (2006) 732], the protocol in this study implements bidirectional communication and authentication, which defends most attacks including the ‘man-in-the-middle’ attack efficiently.

  19. Low Voltage Ride-Through of Doubly Fed Induction Machine using Direct Torque Control Strategy

    Directory of Open Access Journals (Sweden)

    G. Venu Madhav

    2012-12-01

    Full Text Available The wind turbines based Doubly Fed Induction Machine (DFIM not able to support the voltage and the frequency of the grid during and immediately following the grid failure. This would cause major problems for the systems stability, but the turbines should stay connected to the grid in case of a failure. This can be achieved by using crowbar protection in particularly during voltage dips. When low depth voltage dips occur, the necessity of crowbar proctection can be eliminated by using proposed Direct Torque Control (DTC, with a proper rotor flux generation strategy, by which during the fault it will be possible to maintain the machine connected to grid, generating power from the wind, reducing the stator and rotor over currents, eliminating the torque oscillations that normally produce such voltage dips and fast dynamic response accompanies the overall control of the wind turbine.

  20. Direct Instantaneous Torque Control of 4 Phase 8/6 Switched Reluctance Motor

    Directory of Open Access Journals (Sweden)

    Srinivas Pratapgiri

    2011-10-01

    Full Text Available The applications of Switched Reluctance Motor Drives has increased  in the recent past because of advantages like simple structure, no rotor winding, high torque to weight ratio, adaptability to harsh environments like coal mining etc. But the main disadvantage is that torque ripple is high because of the double saliency. This paper presents a high dynamic control technique called Direct Instantaneous Torque Control (DITC where in the torque is maintained within a hysteresis band by changing the switching states of the phases between 1, 0 or -1.Thus torque ripple minimization is an inherent property of DITC. DITC based SRM drive is simulated in MATLAB/SIMULINK environment and results are discussed elaborately

  1. Direct power control of DFIG based on discrete space vector modulation

    Energy Technology Data Exchange (ETDEWEB)

    Verij Kazemi, Mohammad; Sadeghi Yazdankhah, Ahmad; Madadi Kojabadi, Hossein [Electrical Engineering Department, Sahand University of Technology, Tabriz (Iran)

    2010-05-15

    This paper presents a new direct power control (DPC) strategy for a double fed induction generator (DFIG) based wind energy generation system. Switching vectors for rotor side converter were selected from the optimal switching table using the estimated stator flux position and the errors of the active and reactive power. A few number of voltage vectors may cause undesired power and stator current ripple. In this paper the increased number of voltage vectors with application of the Discrete Space Vector Modulation (DSVM) will be presented. Then a new switching table in supersynchronous and subsynchronous frames will be proposed. Simulation results of a 2 MW DFIG system demonstrate the effectiveness and robustness of the proposed control strategy during variations of active and reactive power, machine parameters, and wind speed. (author)

  2. Direct model reference adaptive control using Kp =LDU factorization for multivariable discrete-time plants

    Institute of Scientific and Technical Information of China (English)

    Junling LI; Xuejun XIE; Wei CHEN

    2008-01-01

    For a large class of discrete-time multivariable plants with arbitrary relative degrees.the design and analysis of the direct model reference adaptive control scheme are investigated under less restrictive assumptions.The algorithm is based on a new parametrization dedved from the high frequency gain matrix factorization Kp=LDU under the condition that the signs of the leading principal minors of Kp are known.By reproving the discrete-time Lp and L2δ norm relationship between inputs and outputs,establishing the properties of discrete-time adaptive law,defining the normalizing signal.and relating the signal with all signals in the closed-loop system.the stability and convergence of the discrete-time multivariable model reference adaptive control scheme are analyzed rigorously in a systematic fashion as in the continuous-time case.

  3. Design of one large telescope direct drive control system based on TMS320F28xx

    Science.gov (United States)

    Song, Xiao-li; Wang, Da-xing; Zhang, Chao; Zhang, Zhen-chao; Chen, Li-yan; Ren, Chang-zhi

    2014-08-01

    The mount drive control is the key technique which mostly affects astronomical telescope's resolution and its speed. However, the ultra -lower speed and the giant moment of inertia make it very difficult to be controlled. In this paper, one segmented permanent-magnet synchronous motor (PMSM), 4m diameter, is suggested for the mount driving. A method is presented to drive the motor directly, which is based on TMS320F28XX and Insulated Gate Bipolar Transistor (IGBT) , also, HEIDENHAIN tape is used to detect the absolute position of the motor together with the Hall sensor. The segmented PMSM can work stable and the mount drive can realize nice tracking performance at ultra -lower speed with this drive system.

  4. Direct costs of asthma in Brazil: a comparison between controlled and uncontrolled asthmatic patients

    Directory of Open Access Journals (Sweden)

    L.A. Santos

    2007-07-01

    Full Text Available Asthma is a common chronic illness that imposes a heavy burden on all aspects of the patient's life, including personal and health care cost expenditures. To analyze the direct cost associated to uncontrolled asthma patients, a cross-sectional study was conducted to determine costs related to patients with uncontrolled and controlled asthma. Uncontrolled patient was defined by daytime symptoms more than twice a week or nocturnal symptoms during two consecutive nights or any limitations of activities, or need for relief rescue medication more than twice a week, and an ACQ score less than 2 points. A questionnaire about direct cost stratification in health services, including emergency room visits, hospitalization, ambulatory visits, and asthma medications prescribed, was applied. Ninety asthma patients were enrolled (45 uncontrolled/45 controlled. Uncontrolled asthmatics accounted for higher health care expenditures than controlled patients, US$125.45 and US$15.58, respectively [emergency room visits (US$39.15 vs US$2.70 and hospitalization (US$86.30 vs US$12.88], per patient over 6 months. The costs with medications in the last month for patients with mild, moderate and severe asthma were US$1.60, 9.60, and 25.00 in the uncontrolled patients, respectively, and US$6.50, 19.00 and 49.00 in the controlled patients. In view of the small proportion of uncontrolled subjects receiving regular maintenance medication (22.2% and their lack of resources, providing free medication for uncontrolled patients might be a cost-effective strategy for the public health system.

  5. Generating size-controlled embryoid bodies using laser direct-write

    International Nuclear Information System (INIS)

    Embryonic stem cells (ESCs) have the potential to self-renew and differentiate into any specialized cell type. One common method to differentiate ESCs in vitro is through embryoid bodies (EBs), three-dimensional cellular aggregates that spontaneously self-assemble and generally express markers for the three germ layers, endoderm, ectoderm, and mesoderm. It has been previously shown that both EB size and 2D colony size each influence differentiation. We hypothesized that we could control the size of the EB formed by mouse ESCs (mESCs) by using a cell printing method, laser direct-write (LDW), to control both the size of the initial printed colony and the local cell density in printed colonies. After printing mESCs at various printed colony sizes and printing densities, two-way ANOVAs indicated that the EB diameter was influenced by printing density after three days (p = 0.0002), while there was no effect of the printed colony diameter on the EB diameter at the same timepoint (p = 0.74). There was no significant interaction between these two factors. Tukey's honestly significant difference test showed that high-density colonies formed significantly larger EBs, suggesting that printed mESCs quickly aggregate with nearby cells. Thus, EBs can be engineered to a desired size by controlling printing density, which will influence the design of future differentiation studies. Herein, we highlight the capacity of LDW to control the local cell density and colony size independently, at prescribed spatial locations, potentially leading to better stem cell maintenance and directed differentiation. (paper)

  6. A Novel Direct Torque Control for Induction Machine Drive System with Low Torque And Flux Ripples using XSG

    OpenAIRE

    Souha Boukadida; Soufien Gdaim; Abdellatif Mtibaa

    2014-01-01

    The conventional Direct Torque Control (DTC) is known to produce a quick and robust response in AC drives. However, during steady state, stator flux and electromagnetic torque which results in incorrect speed estimations and acoustical noise. A modified Direct Torque Control (DTC) by using Space Vector Modulation (DTC-SVM) for induction machine is proposed in this paper. Using this control strategy, the ripples introduced in torque and flux are reduced. This paper presents a novel approach to...

  7. Controlled Growth of Copper Oxide Nano-Wires through Direct Oxidation

    Science.gov (United States)

    Hilman, Joann; Neupane, Ravi; Yost, Andrew J.; Chien, Teyu

    Copper oxides, both Cu2O and CuO, have many applications in solar cells, sensors, and nano-electronics. The properties of the copper oxides are further influenced by the dimension of the materials, especially when made in nanoscale. In particular, the properties of the copper oxide nanowires could be tuned by their structures, lengths, and widths. While several methods have been reported to grow nanowires, direct oxidation is arguably the most economical one. This research examines the effects of oxidization duration and temperature in dry air environment on the development of copper oxide nanowires in order to achieve cost effective controllable growth. Using the direct oxidation method in dry air we have demonstrated growth of CuO nano-wires at temperatures as low as 300 °C and as short as 1hr. Furthermore we have observed that the lengths and diameters of the CuO NWs can be controlled by the duration and temperature of the oxidation process. WY NASA Space Grant Consortium.

  8. Optimal control of directional deep brain stimulation in the parkinsonian neuronal network

    Science.gov (United States)

    Fan, Denggui; Wang, Zhihui; Wang, Qingyun

    2016-07-01

    The effect of conventional deep brain stimulation (DBS) on debilitating symptoms of Parkinson's disease can be limited because it can only yield the spherical field. And, some side effects are clearly induced with influencing their adjacent ganglia. Recent experimental evidence for patients with Parkinson's disease has shown that a novel DBS electrode with 32 independent stimulation source contacts can effectively optimize the clinical therapy by enlarging the therapeutic windows, when it is applied on the subthalamic nucleus (STN). This is due to the selective activation in clusters of various stimulation contacts which can be steered directionally and accurately on the targeted regions of interest. In addition, because of the serious damage to the neural tissues, the charge-unbalanced stimulation is not typically indicated and the real DBS utilizes charge-balanced bi-phasic (CBBP) pulses. Inspired by this, we computationally investigate the optimal control of directional CBBP-DBS from the proposed parkinsonian neuronal network of basal ganglia-thalamocortical circuit. By appropriately tuning stimulation for different neuronal populations, it can be found that directional steering CBBP-DBS paradigms are superior to the spherical case in improving parkinsonian dynamical properties including the synchronization of neuronal populations and the reliability of thalamus relaying the information from cortex, which is in a good agreement with the physiological experiments. Furthermore, it can be found that directional steering stimulations can increase the optimal stimulation intensity of desynchronization by more than 1 mA compared to the spherical case. This is consistent with the experimental result with showing that there exists at least one steering direction that can allow increasing the threshold of side effects by 1 mA. In addition, we also simulate the local field potential (LFP) and dominant frequency (DF) of the STN neuronal population induced by the activation

  9. Highly directional transurethral ultrasound applicators with rotational control for MRI-guided prostatic thermal therapy

    International Nuclear Information System (INIS)

    Transurethral ultrasound applicators with highly directional energy deposition and rotational control were investigated for precise treatment of benign prostatic hyperplasia (BPH) and adenocarcinoma of the prostate (CaP). Two types of catheter-based applicators were fabricated, using either sectored tubular (3.5 mm OD x 10 mm) or planar transducers (3.5 mm x 10 mm). They were constructed to be MRI compatible, minimally invasive and allow for manual rotation of the transducer array within a 10 mm cooling balloon. In vivo evaluations of the applicators were performed in canine prostates (n 3) using MRI guidance (0.5 T interventional magnet). MR temperature imaging (MRTI) utilizing the proton resonance frequency shift method was used to acquire multiple-slice temperature overlays in real time for monitoring and guiding the thermal treatments. Post-treatment T1-weighted contrast-enhanced imaging and triphenyl tetrazolium chloride stained tissue sections were used to define regions of tissue coagulation. Single sonications with the tubular applicator ) produced coagulated zones covering a wedge of the prostate extending from 1-2 mm outside the urethra to the outer boundary of the gland (16 mm radial coagulation). Single sonications with the planar applicator (15-20 W, 10 min, ∼8 MHz) generated thermal lesions of ∼30 extending to the prostate boundary. Multiple sequential sonications (sweeping) of a planar applicator (12 W with eight rotations of 30 each) demonstrated controllable coagulation of a 270 contiguous section of the prostate extending to the capsule boundary. The feasibility of using highly directional transurethral ultrasound applicators with rotational capabilities to selectively coagulate regions of the prostate while monitoring and controlling the treatments with MRTI was demonstrated in this study

  10. p53-directed translational control can shape and expand the universe of p53 target genes.

    Science.gov (United States)

    Zaccara, S; Tebaldi, T; Pederiva, C; Ciribilli, Y; Bisio, A; Inga, A

    2014-10-01

    The increasing number of genome-wide transcriptome analyses focusing on p53-induced cellular responses in many cellular contexts keeps adding to the already numerous p53-regulated transcriptional networks. To investigate post-transcriptional controls as an additional dimension of p53-directed gene expression responses, we performed a translatome analysis through polysomal profiling on MCF7 cells upon 16 hours of doxorubicin or nutlin-3a treatment. The comparison between the transcriptome and the translatome revealed a considerable level of uncoupling, characterized by genes whose transcription variations did not correlate with translation variations. Interestingly, uncoupled genes were associated with apoptosis, DNA and RNA metabolism and cell cycle functions, suggesting that post-transcriptional control can modulate classical p53-regulated responses. Furthermore, even for well-established p53 targets that were differentially expressed both at the transcriptional and translational levels, quantitative differences between the transcriptome, subpolysomal and polysomal RNAs were evident. As we searched mechanisms underlying gene expression uncoupling, we identified the p53-dependent modulation of six RNA-binding proteins, where hnRNPD (AUF1) and CPEB4 are direct p53 transcriptional targets, whereas SRSF1, DDX17, YBX1 and TARDBP are indirect targets (genes modulated preferentially in the subpolysomal or polysomal mRNA level) modulated at the translational level in a p53-dependent manner. In particular, YBX1 translation appeared to be reduced by p53 via two different mechanisms, one related to mTOR inhibition and the other to miR-34a expression. Overall, we established p53 as a master regulator of translational control and identified new p53-regulated genes affecting translation that can contribute to p53-dependent cellular responses. PMID:24926617

  11. Speed sensorless direct torque control of IMs [induction motors] with rotor resistance estimation

    Energy Technology Data Exchange (ETDEWEB)

    Murat Barut; Metin Gokasan [Istanbul Technical University (Turkey). Faculty of Engineering; Seta Bogosyan [University of Alaska, Fairbanks, AK (United States). Dept. of Electrical and Computer Engineering

    2005-02-01

    Direct torque control (DTC) of induction motors (IMs) requires an accurate knowledge on the amplitude and angular position of the controlled flux in addition to the information related to angular velocity for velocity control applications. However, unknown load torque and uncertainties related to stator/rotor resistances due to operating conditions constitute major challenges for the performance of such systems. The determination of stator resistance can be performed by measurements, but methods must be developed for estimation and identification of rotor resistance and load torque. In this study, an EKF based solution is sought for determination of the rotor resistance and load torque as well as the above-mentioned states required for DTC. The EKF algorithm used in conjunction with the speed sensorless DTC is tested under eleven scenarios comprised of various changes made in the velocity reference beside the load torque and rotor resistance values assigned in the model. With no a priori information in the estimated states and parameters, it has been demonstrated that the EKF estimation and sensorless DTC perform quite well in spite of the uncertainties and variations imposed on the system. (author)

  12. Speed sensorless direct torque control of IMs with rotor resistance estimation

    International Nuclear Information System (INIS)

    Direct torque control (DTC) of induction motors (IMs) requires an accurate knowledge on the amplitude and angular position of the controlled flux in addition to the information related to angular velocity for velocity control applications. However, unknown load torque and uncertainties related to stator/rotor resistances due to operating conditions constitute major challenges for the performance of such systems. The determination of stator resistance can be performed by measurements, but methods must be developed for estimation and identification of rotor resistance and load torque. In this study, an EKF based solution is sought for determination of the rotor resistance and load torque as well as the above mentioned states required for DTC. The EKF algorithm used in conjunction with the speed sensorless DTC is tested under eleven scenarios comprised of various changes made in the velocity reference beside the load torque and rotor resistance values assigned in the model. With no a priori information in the estimated states and parameters, it has been demonstrated that the EKF estimation and sensorless DTC perform quite well in spite of the uncertainties and variations imposed on the system

  13. Speed sensorless direct torque control of IMs with rotor resistance estimation

    Energy Technology Data Exchange (ETDEWEB)

    Barut, Murat; Bogosyan, Seta E-mail: s.bogosyan@uaf.edu; Gokasan, Metin

    2005-02-01

    Direct torque control (DTC) of induction motors (IMs) requires an accurate knowledge on the amplitude and angular position of the controlled flux in addition to the information related to angular velocity for velocity control applications. However, unknown load torque and uncertainties related to stator/rotor resistances due to operating conditions constitute major challenges for the performance of such systems. The determination of stator resistance can be performed by measurements, but methods must be developed for estimation and identification of rotor resistance and load torque. In this study, an EKF based solution is sought for determination of the rotor resistance and load torque as well as the above mentioned states required for DTC. The EKF algorithm used in conjunction with the speed sensorless DTC is tested under eleven scenarios comprised of various changes made in the velocity reference beside the load torque and rotor resistance values assigned in the model. With no a priori information in the estimated states and parameters, it has been demonstrated that the EKF estimation and sensorless DTC perform quite well in spite of the uncertainties and variations imposed on the system.

  14. Google Glass-Directed Monitoring and Control of Microfluidic Biosensors and Actuators

    Science.gov (United States)

    Zhang, Yu Shrike; Busignani, Fabio; Ribas, João; Aleman, Julio; Rodrigues, Talles Nascimento; Shaegh, Seyed Ali Mousavi; Massa, Solange; Rossi, Camilla Baj; Taurino, Irene; Shin, Su-Ryon; Calzone, Giovanni; Amaratunga, Givan Mark; Chambers, Douglas Leon; Jabari, Saman; Niu, Yuxi; Manoharan, Vijayan; Dokmeci, Mehmet Remzi; Carrara, Sandro; Demarchi, Danilo; Khademhosseini, Ali

    2016-03-01

    Google Glass is a recently designed wearable device capable of displaying information in a smartphone-like hands-free format by wireless communication. The Glass also provides convenient control over remote devices, primarily enabled by voice recognition commands. These unique features of the Google Glass make it useful for medical and biomedical applications where hands-free experiences are strongly preferred. Here, we report for the first time, an integral set of hardware, firmware, software, and Glassware that enabled wireless transmission of sensor data onto the Google Glass for on-demand data visualization and real-time analysis. Additionally, the platform allowed the user to control outputs entered through the Glass, therefore achieving bi-directional Glass-device interfacing. Using this versatile platform, we demonstrated its capability in monitoring physical and physiological parameters such as temperature, pH, and morphology of liver- and heart-on-chips. Furthermore, we showed the capability to remotely introduce pharmaceutical compounds into a microfluidic human primary liver bioreactor at desired time points while monitoring their effects through the Glass. We believe that such an innovative platform, along with its concept, has set up a premise in wearable monitoring and controlling technology for a wide variety of applications in biomedicine.

  15. Development of Anodic Flux and Temperature Controlling System for Micro Direct Methanol Fuel Cell

    International Nuclear Information System (INIS)

    Micro Direct Methanol Fuel Cell (μDMFC) is a kind of newly developed power sources, which effective apparatus for its performance evaluation is still in urgent need at present. In this study, a testing system was established for the purpose of testing the continuous working performance such as micro flux and temperature of μDMFC. In view of the temperature controlling for micro-flux liquid fuel, a heating block with labyrinth-like single pass channel inside for heating up the methanol solution was fabricated. A semiconductorrefrigerating chip was utilized to heat and cool the liquid flow during testing procedures. On the other hand, the two channels of a high accuracy double-channel syringe pump that can suck and pump in turn so as to transport methanol solution continuously was adopted. Based on the requirements of wide-ranged temperature and micro flux controlling, the solenoid valves and the correlative component were used. A hydraulic circuit, which can circulate the fed methanol cold to hot in turn, has also been constructed to test the fatigue life of the μDMFC. The automatic control was actualized by software module written with Visual C++. Experimental results show that the system is perfect in stability and it may provide an important and advanced evaluation apparatus to satisfy the needs for real time performance testing of μDMFC

  16. Future Direction of the Instrumentation and Control System for Security of Nuclear Facilities

    International Nuclear Information System (INIS)

    Instrumentation and control systems are pervasively used as a vital component in modern industries. Nuclear facilities, such as nuclear power plants (NPPs), originally use I and C systems for plant status monitoring, processes control, and many other purposes. After some events that raised security concerns, application areas of I and C systems have been expanded to physical protection of nuclear material and facilities. As nuclear policies over the world are strengthening security issues, the future direction of roles and technical requirements of security related I and C systems is described: An introduction of I and C systems, especially digitalized I and C systems, to security of nuclear facilities requires many careful considerations, such as system integration, verification and validation (V/V), etc. Institute of Nuclear Nonproliferation and Control (KINAC) established 'International Nuclear Nonproliferation and Security Academy, INSA' in 2014. One of the main achievements of INSA is test-bed implementation for technical criteria development of nuclear facilities' physical protection systems (PPSs) as well as for education and training of those systems. The test bed was modified and improved more suitably from the previous version to modern PPSs including state-of-the-art I and C technologies. KINAC is confident in the new test bed to become a fundamental technical basis of security related I and C systems in near future

  17. Development of Anodic Flux and Temperature Controlling System for Micro Direct Methanol Fuel Cell

    Science.gov (United States)

    Li, M. M.; Liu, C.; Liang, J. S.; Wu, C. B.; Xu, Z.

    2006-10-01

    Micro Direct Methanol Fuel Cell (μDMFC) is a kind of newly developed power sources, which effective apparatus for its performance evaluation is still in urgent need at present. In this study, a testing system was established for the purpose of testing the continuous working performance such as micro flux and temperature of μDMFC. In view of the temperature controlling for micro-flux liquid fuel, a heating block with labyrinth-like single pass channel inside for heating up the methanol solution was fabricated. A semiconductorrefrigerating chip was utilized to heat and cool the liquid flow during testing procedures. On the other hand, the two channels of a high accuracy double-channel syringe pump that can suck and pump in turn so as to transport methanol solution continuously was adopted. Based on the requirements of wide-ranged temperature and micro flux controlling, the solenoid valves and the correlative component were used. A hydraulic circuit, which can circulate the fed methanol cold to hot in turn, has also been constructed to test the fatigue life of the μDMFC. The automatic control was actualized by software module written with Visual C++. Experimental results show that the system is perfect in stability and it may provide an important and advanced evaluation apparatus to satisfy the needs for real time performance testing of μDMFC.

  18. Google Glass-Directed Monitoring and Control of Microfluidic Biosensors and Actuators.

    Science.gov (United States)

    Zhang, Yu Shrike; Busignani, Fabio; Ribas, João; Aleman, Julio; Rodrigues, Talles Nascimento; Shaegh, Seyed Ali Mousavi; Massa, Solange; Baj Rossi, Camilla; Taurino, Irene; Shin, Su-Ryon; Calzone, Giovanni; Amaratunga, Givan Mark; Chambers, Douglas Leon; Jabari, Saman; Niu, Yuxi; Manoharan, Vijayan; Dokmeci, Mehmet Remzi; Carrara, Sandro; Demarchi, Danilo; Khademhosseini, Ali

    2016-01-01

    Google Glass is a recently designed wearable device capable of displaying information in a smartphone-like hands-free format by wireless communication. The Glass also provides convenient control over remote devices, primarily enabled by voice recognition commands. These unique features of the Google Glass make it useful for medical and biomedical applications where hands-free experiences are strongly preferred. Here, we report for the first time, an integral set of hardware, firmware, software, and Glassware that enabled wireless transmission of sensor data onto the Google Glass for on-demand data visualization and real-time analysis. Additionally, the platform allowed the user to control outputs entered through the Glass, therefore achieving bi-directional Glass-device interfacing. Using this versatile platform, we demonstrated its capability in monitoring physical and physiological parameters such as temperature, pH, and morphology of liver- and heart-on-chips. Furthermore, we showed the capability to remotely introduce pharmaceutical compounds into a microfluidic human primary liver bioreactor at desired time points while monitoring their effects through the Glass. We believe that such an innovative platform, along with its concept, has set up a premise in wearable monitoring and controlling technology for a wide variety of applications in biomedicine. PMID:26928456

  19. Direct Torque Control of Four Switch Three Phase Inverter fed Induction Motor Sensorless Speed Drive

    Directory of Open Access Journals (Sweden)

    Mohamed K Metwally

    2014-10-01

    Full Text Available This paper presents sensorless speed control of induction motor (IM using four switch three phase inverter (FSTPI with direct torque and flux control (DTFC. The proposed sensorless DTFC system consists of an adaptive observer of rotor flux to accurately estimate stator resistance and speed simultaneously, without affecting drive performances. The switching technique for DTFC of IM using FSTPI in low power application is based on the principle of similarity between FSTPI and SSTPI (six switch three phase inverter, where the αβ plan is divided into 6 sectors and the formation of the voltage space vector is done in the same way as for SSTPI by using effective (mean vectors. This approach allows using the well-known established switching table of SSTPI for FSTPI. The simulation results indicates that the sensorless speed control of FSTPI fed IM with DTFC and adaptive observer provides accurate estimate, good trajectory tracking with different dynamics performance. The experimental results verify the effectiveness of the proposed method at different operating points.

  20. Open loop thanks to direct torque control (DTC). Motor control without feedback loop; Open loop dank direkter Drehmomentregelung (DTC). Hochwertige Motorregelung ohne Rueckfuehrung

    Energy Technology Data Exchange (ETDEWEB)

    Link, Michael [ABB Automation Products GmbH, Ladenburg (Germany)

    2009-07-01

    Servo drives are used in various applications. The range of applications is huge and thus also requirements to the drive system. Mainly, a fast torque and speed control is required. This is the domaine of direct torque control (DTC). In many applications DTC can meet this challenge to control the motor with full torque at zero speed. The servo converter based on DTC technology provides a control concept for synchronous and asynchronous motors for both closed loop and open loop control. DTC controlled drives support the whole range from open loop up to high performance motion control applications. (orig.)

  1. Global tracking for a class of uncertain nonlinear systems with unknown sign-switching control direction by output feedback

    Science.gov (United States)

    Roux Oliveira, Tiago; Jacoud Peixoto, Alessandro; Hsu, Liu

    2015-09-01

    This paper addresses the design of a sliding mode controller for a class of high-order uncertain nonlinear plants with unmatched state-dependent nonlinearities and unknown sign of the high frequency gain, i.e., the control direction is assumed unknown. Differently from most previous studies, the control direction is allowed to switch its sign. We show that it is possible to obtain global exact tracking using only output-feedback by coupling a relay periodic switching function with a norm state observer. One significant advantage of the new scheme is its robustness and improved transient response under arbitrary changes of the control direction which have been theoretically demonstrated for jump variations and successfully tested by simulations. The proposed controller is also evaluated with a DC motor control experiment.

  2. Filter-based control of particulate matter from a lean gasoline direct injection engine

    Energy Technology Data Exchange (ETDEWEB)

    Parks, II, James E [ORNL; Lewis Sr, Samuel Arthur [ORNL; DeBusk, Melanie Moses [ORNL; Prikhodko, Vitaly Y [ORNL; Storey, John Morse [ORNL

    2016-01-01

    New regulations requiring increases in vehicle fuel economy are challenging automotive manufacturers to identify fuel-efficient engines for future vehicles. Lean gasoline direct injection (GDI) engines offer significant increases in fuel efficiency over the more common stoichiometric GDI engines already in the marketplace. However, particulate matter (PM) emissions from lean GDI engines, particularly during stratified combustion modes, are problematic for lean GDI technology to meet U.S. Environmental Protection Agency Tier 3 and other future emission regulations. As such, the control of lean GDI PM with wall-flow filters, referred to as gasoline particulate filter (GPF) technology, is of interest. Since lean GDI PM chemistry and morphology differ from diesel PM (where more filtration experience exists), the functionality of GPFs needs to be studied to determine the operating conditions suitable for efficient PM removal. In addition, lean GDI engine exhaust temperatures are generally higher than diesel engines which results in more continuous regeneration of the GPF and less presence of the soot cake layer common to diesel particulate filters. Since the soot layer improves filtration efficiency, this distinction is important to consider. Research on the emission control of PM from a lean GDI engine with a GPF was conducted on an engine dynamometer. PM, after dilution, was characterized with membrane filters, organic vs. elemental carbon characterization, and size distribution techniques at various steady state engine speed and load points. The engine was operated in three primary combustion modes: stoichiometric, lean homogeneous, and lean stratified. In addition, rich combustion was utilized to simulate PM from engine operation during active regeneration of lean NOx control technologies. High (>95%) PM filtration efficiencies were observed over a wide range of conditions; however, some PM was observed to slip through the GPF at high speed and load conditions. The

  3. Influence of Transcranial Direct Current Stimulation to the Cerebellum on Standing Posture Control

    Science.gov (United States)

    Inukai, Yasuto; Saito, Kei; Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Onishi, Hideaki

    2016-01-01

    Damage to the vestibular cerebellum results in dysfunctional standing posture control. Patients with cerebellum dysfunction have a larger sway in the center of gravity while standing compared with healthy subjects. Transcranial direct current stimulation (tDCS) is a noninvasive technique for selectively exciting or inhibiting specific neural structures with potential applications in functional assessment and treatment of neural disorders. However, the specific stimulation parameters for influencing postural control have not been assessed. In this study, we investigated the influence of tDCS when applied over the cerebellum on standing posture control. Sixteen healthy subjects received tDCS (20 min, 2 mA) over the scalp 2 cm below the inion. In Experiment 1, all 16 subjects received tDCS under three stimulus conditions, Sham, Cathodal, and Anodal, in a random order with the second electrode placed on the forehead. In Experiment 2, five subjects received cathodal stimulation only with the second electrode placed over the right buccinator muscle. Center of gravity sway was measured twice for 60 s before and after tDCS in a standing posture with eyes open and legs closed, and average total locus length, locus length per second, rectangular area, and enveloped area were calculated. In Experiment 1, total locus length and locus length per second decreased significantly after cathodal stimulation but not after anodal or sham stimulation, while no tDCS condition influenced rectangular or enveloped areas. In Experiment 2, cathodal tDCS again significantly reduced total locus length and locus length per second but not rectangular and enveloped areas. The effects of tDCS on postural control are polarity-dependent, likely reflecting the selective excitation or inhibition of cerebellar Purkinje cells. Cathodal tDCS to the cerebellum of healthy subjects can alter body sway (velocity).

  4. Expression liver-directed genes by employing synthetic transcriptional control units

    Institute of Scientific and Technical Information of China (English)

    Marie-Luise Lemken; Wolfgang A. Wybranietz; Ulrike Schmidt; Florian Graepler; Sorin Armeanu; Michael Bitzer; Ulrich M. Lauer

    2005-01-01

    AIM: To generate and characterize the synthetic transcriptional control units for transcriptional targeting of the liver,thereby compensating for the lack of specificity of currently available gene therapeutic vector systems.METHODS: Synthetic transcriptional control unit constructs were generated and analyzed for transcriptional activities in different cell types by FACS quantification, semi-quantitative RT-PCR, and Western blotting. RESULTS: A new bifunctionally-enhanced green fluorescent protein (EGFP)/neor fusion gene cassette was generated,and could flexibly be used both for transcript quantification and for selection of stable cell clones. Then, numerous synthetic transcriptional control units consisting of a minimal promoter linked to "naturally" derived composite enhancer elements from liver-specific expressed genes or binding sites of liver-specific transcription factors were inserted upstream of this reporter cassette. Following liposome-mediated transfection, EGFP reporter protein quantification by FACS analysis identified constructs encoding multimerized composite elements of the apolipoprotein B100 (ApoB) promoter or the ornithin transcarbamoylase (OTC) enhancer to exhibit maximum transcriptional activities in liver originating cell lines, but only background levels in non-liver originating cell lines. In contrast, constructs encoding only singular binding sites of liver-specific transcription factors, namely hepatocyte nuclear factor (HNF)1, HNF3, HNF4, HNF5, or CAAT/enhancer binding protein (C/EBP) only achieved background levels of EGFP expression. Finally, both semi-quantitative RT-PCR and Western blotting analysis of Hep3B cells demonstrated maximum transcriptional activities for a multimeric 4xApoB cassette construct, which fully complied with the data obtained by initial FACS analysis.CONCLUSION: Synthetic transcriptional control unit constructs not only exhibit a superb degree of structural compactness, but also provide new means for liver-directed

  5. The problem of ensuring efficiency of internal control in a budget institution and directions of its solution

    Directory of Open Access Journals (Sweden)

    Synyugina Nataliya V.

    2013-03-01

    Full Text Available The article analyses the problem of ensuring efficient and legitimate functioning of the system of state finance in Ukraine. It justifies a necessity of introduction of internal control into budget institutions, which conforms with the Concept of Development of State Internal Financial Control in Ukraine. It identifies tasks of internal control in budget institutions. It identifies general and special criteria of assessment of efficiency of internal control in budget institutions. It offers directions of ensuring efficiency of internal control in Ukraine. Its scientific novelty lies in identification of tasks of internal control in a budget institution and proposed directions of ensuring efficiency of internal control into budget institutions. Practical significance is in a possibility of application of the author’s conclusion in practical activity of managers of budget funds with the aim to organise efficient internal control.

  6. The Controlled Cortical Impact Model: Applications, Considerations for Researchers, and Future Directions.

    Science.gov (United States)

    Osier, Nicole D; Dixon, C Edward

    2016-01-01

    Controlled cortical impact (CCI) is a mechanical model of traumatic brain injury (TBI) that was developed nearly 30 years ago with the goal of creating a testing platform to determine the biomechanical properties of brain tissue exposed to direct mechanical deformation. Initially used to model TBIs produced by automotive crashes, the CCI model rapidly transformed into a standardized technique to study TBI mechanisms and evaluate therapies. CCI is most commonly produced using a device that rapidly accelerates a rod to impact the surgically exposed cortical dural surface. The tip of the rod can be varied in size and geometry to accommodate scalability to difference species. Typically, the rod is actuated by a pneumatic piston or electromagnetic actuator. With some limits, CCI devices can control the velocity, depth, duration, and site of impact. The CCI model produces morphologic and cerebrovascular injury responses that resemble certain aspects of human TBI. Commonly observed are graded histologic and axonal derangements, disruption of the blood-brain barrier, subdural and intra-parenchymal hematoma, edema, inflammation, and alterations in cerebral blood flow. The CCI model also produces neurobehavioral and cognitive impairments similar to those observed clinically. In contrast to other TBI models, the CCI device induces a significantly pronounced cortical contusion, but is limited in the extent to which it models the diffuse effects of TBI; a related limitation is that not all clinical TBI cases are characterized by a contusion. Another perceived limitation is that a non-clinically relevant craniotomy is performed. Biomechanically, this is irrelevant at the tissue level. However, craniotomies are not atraumatic and the effects of surgery should be controlled by including surgical sham control groups. CCI devices have also been successfully used to impact closed skulls to study mild and repetitive TBI. Future directions for CCI research surround continued

  7. Direct Torque Control of Sensorless Induction Machine Drives: A Two-Stage Kalman Filter Approach

    Directory of Open Access Journals (Sweden)

    Jinliang Zhang

    2015-01-01

    Full Text Available Extended Kalman filter (EKF has been widely applied for sensorless direct torque control (DTC in induction machines (IMs. One key problem associated with EKF is that the estimator suffers from computational burden and numerical problems resulting from high order mathematical models. To reduce the computational cost, a two-stage extended Kalman filter (TEKF based solution is presented for closed-loop stator flux, speed, and torque estimation of IM to achieve sensorless DTC-SVM operations in this paper. The novel observer can be similarly derived as the optimal two-stage Kalman filter (TKF which has been proposed by several researchers. Compared to a straightforward implementation of a conventional EKF, the TEKF estimator can reduce the number of arithmetic operations. Simulation and experimental results verify the performance of the proposed TEKF estimator for DTC of IMs.

  8. Direct torque control em máquinas assíncronas

    OpenAIRE

    Magalhães, Pedro Mendes de Lacerda Peixoto de

    2009-01-01

    Este trabalho incide sobre o DTC (Direct Torque Control ), técnica de controlo de máquinas eléctricas(polifásicas) de corrente alternada, em particular a máquina assíncrona, e o seu objectivo é construir bases para trabalho futuro nesta área, nomeadamente através da análise crítica dos componentes elementares da técnica e seu desempenho. A realização deste trabalho prevê o estudo teórico do método de controlo e avaliação das suas características a partir de simulação e implementação prática...

  9. Controlling directed self-assembly of gold nanorods in patterned PS-b-PMMA thin films

    International Nuclear Information System (INIS)

    We present a facile strategy for the directed self-assembly of gold nanorods (AuNRs) in patterned block copolymer (BCP) thin films. Parallel arrangement of AuNRs relative to the geometric confinement generated by selective removal of one block domain was achieved. Deposition of AuNRs with aspect ratios from 3.3 to 5.8 was accomplished and the alignment of the NRs within the channels was controlled primarily by capillary forces and the channel geometry. Ordered AuNR assembly in the BCP pattern can be achieved at high surface coverages, >30%, though the surface coverage depends on the aspect ratio of the NRs. Larger NRs align in the channels more readily, but pack at slightly lower densities. (paper)

  10. Direct control of the small-scale energy balance in 2D fluid dynamics

    CERN Document Server

    Frank, Jason; Myerscough, Keith

    2014-01-01

    We explore the direct modification of the pseudo-spectral truncation of 2D, incompressible fluid dynamics to maintain a prescribed kinetic energy spectrum. The method provides a means of simulating fluid states with defined spectral properties, for the purpose of matching simulation statistics to given information, arising from observations, theoretical prediction or high fidelity simulation. In the scheme outlined here, Nos\\'e-Hoover thermostats, commonly used in molecular dynamics, are introduced as feedback controls applied to energy shells of the Fourier-discretized Navier-Stokes equations. As we demonstrate in numerical experiments, the dynamical properties (quantified using autocorrelation functions) are only modestly perturbed by our device, while ensemble dispersion is significantly enhanced in comparison with simulations of a corresponding truncation incorporating hyperviscosity.

  11. Explicit Control of Implicit Responses: Simple Directives can alter IAT Performance.

    Science.gov (United States)

    Wallaert, Matthew; Ward, Andrew; Mann, Traci

    2010-03-01

    Research has begun to reveal the malleability of implicit prejudice. One measure of this construct, the race Implicit Association Test (IAT), represents a widely-used tool to assess individuals' positive and negative associations with different racial groups. In two studies, we demonstrate the capacity of salient pressures to alter implicit racial responses. In Study 1, an enhancement of promoting pressures through an explicit instruction to stereotype was sufficient to increase pro-White bias on the IAT. In Study 2, an enhancement of inhibiting pressures through a simple instruction to avoid stereotyping was sufficient to reduce pro-White bias. Taken together, the studies suggest that implicit prejudice is amenable to voluntary control through the use of simple, direct means. PMID:21769299

  12. Dementia in residential care: education intervention trial (DIRECT; protocol for a randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Lautenschlager Nicola T

    2010-05-01

    Full Text Available Abstract Background There is scope to improve the quality of life (QOL of people with dementia living in residential care facilities (RCF. The DIRECT study will determine if delivery of education to General Practitioners (GPs and care staff improves the quality of life of residential care recipients with cognitive impairment. Methods/Design A prospective randomised controlled trial conduced in residential aged care facilities in the metropolitan area of Perth, Western Australia. Participants are care facility residents, aged 65 years and older and with mini-mental state examination scores less than 25. GPs and care facility staff have been independently randomised to intervention or control groups. An education programme, designed to meet the perceived needs of learners, will be delivered to GPs and care staff in the intervention groups. The primary outcome of the study will be quality of life of the people with dementia, measured using the QOL-Alzheimer's Disease Scale (QOL-AD and Alzheimer Disease Related QOL Scale (ADRQL, 4 weeks and 6 months after the conclusion of the education intervention. Results Recruitment of 351 people with dementia, cared for by staff in 39 residential facilities and 55 GPs, was undertaken between May 2007 and July 2008. Collection of baseline data is complete. Education has been delivered to GPs and Care staff between September 2008 and July 2009. Follow- up data collection is underway. Discussion The study results will have tangible implications for proprietors, managers and staff from the residential care sector and policy makers. The results have potential to directly benefit the quality of life of both patients and carers. Trial registration These trial methods have been prospectively registered (ACTRN12607000417482.

  13. Exploring Direct 3D Interaction for Full Horizontal Parallax Light Field Displays Using Leap Motion Controller

    Directory of Open Access Journals (Sweden)

    Vamsi Kiran Adhikarla

    2015-04-01

    Full Text Available This paper reports on the design and evaluation of direct 3D gesture interaction with a full horizontal parallax light field display. A light field display defines a visual scene using directional light beams emitted from multiple light sources as if they are emitted from scene points. Each scene point is rendered individually resulting in more realistic and accurate 3D visualization compared to other 3D displaying technologies. We propose an interaction setup combining the visualization of objects within the Field Of View (FOV of a light field display and their selection through freehand gesture tracked by the Leap Motion Controller. The accuracy and usefulness of the proposed interaction setup was also evaluated in a user study with test subjects. The results of the study revealed high user preference for free hand interaction with light field display as well as relatively low cognitive demand of this technique. Further, our results also revealed some limitations and adjustments of the proposed setup to be addressed in future work.

  14. Geologically controlled bi-directional exchange of groundwater with a hypersaline lake in the Canadian prairies

    Science.gov (United States)

    Bentley, Laurence R.; Hayashi, Masaki; Zimmerman, Elena P.; Holmden, Chris; Kelley, Lynn I.

    2016-06-01

    Hypersaline lakes occur in hydrologically closed basins due to evaporitic enrichment of dissolved salts transported to the lakes by surface water and groundwater. At the hypersaline Lydden Lake in Saskatchewan, Canada, groundwater/lake-water interaction is strongly influenced by the geological heterogeneity of glacial deposits, whereby a highly permeable glaciofluvial sand/gravel deposit is underlain by glaciolacustrine deposits consisting of dense clay interspersed with silt/sand lenses. Pressure head distribution in a near shore area indicates a bi-directional flow system. It consists of topographically driven flow of fresh groundwater towards the lake in the sand/gravel aquifer and density-driven, landward flow of saline groundwater in the underlying glaciolacustrine deposits. Electrical resistivity tomography, and chemical and isotopic composition of groundwater clearly show the landward intrusion of saline water in the heterogeneous unit. The feasibility of bi-directional flow and transport is supported by numerical simulations of density-coupled groundwater flow and transport. The results suggest that the geologically controlled groundwater exchange processes have substantial influences on both inputs and outputs of dissolved minerals in hypersaline lakes in closed basins.

  15. Improvement of Torque Response and Reduction of Error Speed in Direct Torque Control of Induction Motor by Fuzzy Logic

    OpenAIRE

    HamidReza Fakharizadeh

    2009-01-01

    In this paper, the direct torque control (DTC) technique is used for the speed control of induction motors, and then fuzzy logic is used for designing the speed controller, the improvement of torque response and the reduction of the speed error. The DTC method is utilized due to its quick torque response and robustness against sudden load variations. Also, by applying fuzzy logic unpredicted problems can be solved. The fuzzy logic also can improve the work of the speed control in induction mo...

  16. Neuro-fuzzy speed tracking control of traveling-wave ultrasonic motor drives using direct pulse width modulation

    OpenAIRE

    Chau, KT; Chung, SW

    2002-01-01

    The traveling-wave ultrasonic motor (TUSM) drive offers many distinct advantages but suffers from severe system nonlinearities and parameter variations especially during speed control. This paper presents a new speed tracking control system for the TUSM drive, which newly incorporates neuro-fuzzy control and direct pulse width modulation to solve the problem of nonlinearities and variations. Increasingly, the proposed control system is digitally implemented by a low-cost digital signal proces...

  17. Neuro-Fuzzy Speed Tracking Control of Traveling-Wave Ultrasonic Motor Drives Using Direct Pulsewidth Modulation

    OpenAIRE

    Chau, KT; Chung, SW; Chan, CC

    2003-01-01

    The traveling-wave ultrasonic motor (TWUM) drive offers many distinct advantages but suffers from severe system nonlinearities and parameter variations, especially during speed control. This paper presents a new speed tracking control system for the TWUM drive, which newly incorporates neuro-fuzzy control and direct pulsewidth modulation to solve the problem of nonlinearities and variations. The proposed control system is digitally implemented by a low-cost digital-signal-processor-based micr...

  18. Factors associated with compliance with community directed treatment with ivermectin for onchocerciasis control in Southwestern Ethiopia

    Directory of Open Access Journals (Sweden)

    Wondafrash Mekite

    2010-06-01

    Full Text Available Abstract Background Although ivermectin is distributed free of charge through the African Programme for Onchocerciasis Control (APOC, not all eligible individuals within communities receive the annual treatment. This poses a serious threat to efforts aimed to control onchocerciasis. This study attempts to determine factors associated with compliance to Community Directed Treatment with Ivermectin (CDTI and provides a basis for trying to understand how best to sustain long-term compliance in order to achieve success in the control of onchocerciasis. Methods An unmatched case-control study was conducted in Bebeka coffee plantation southwest Ethiopia. Cases were, compliant i.e., those individuals who had been registered on the relevant treatment registers and had taken all the five annual doses of Ivermectin. Controls were non-compliant, i.e. those individuals who had been recorded in the relevant treatment registers during the first treatment round(2003, and did not take at least two doses of which one being in the last treatment round (2007. Data were collected using a pre-tested interviewer administered structured questionnaire. Data were edited, cleaned, coded and analyzed using SPSS version 12.0.1 for Microsoft Windows. Multiple logistic regression models was used to identify factors associated with compliance to ivermectin. Results From the total of 456 individuals selected for administration of the survey questionnaire, 450(225 cases and 225 controls were contacted and completed the study 2 refused and 4 were unavailable. Five factors associated with compliance were identified: high risk perception [Adjusted Odds Ratio(AOR = 1.98, 95% Confidence Interval (CI, 1.32-2.95], one's family support [AOR = 1.86, 95% CI, 1.22-2.84], perceiving that the Community Drug Distributors (CDDs are doing their work well [AOR = 2.84, 95% CI, 1.50-5.37] and perceiving measuring height is the best way to determine a person's treatment dose [AOR = 6.37, 95% CI, 2

  19. Dual-color control and inhibition of direct laser writing in silver-containing phosphate glasses.

    Science.gov (United States)

    Petit, Yannick; Mishchik, Konstantin; Varkentina, Nadezda; Marquestaut, Nicolas; Royon, Arnaud; Manek-Hönninger, Inka; Cardinal, Thierry; Canioni, Lionel

    2015-09-01

    We report on dual-color control of femtosecond direct laser writing (DLW) in a noncommercial silver-containing zinc phosphate glass, thanks to an additional illumination with a cw (continuous wave) UV laser, either after the femtosecond irradiation or simultaneously. By tuning the cw UV power, we demonstrate the tunable control and inhibition of the production efficiency of laser-induced fluorescent silver clusters, leading up to 100% inhibition for simultaneous co-illumination when the laser writing is performed close enough to the permanent structuring threshold. The role of the cw UV illumination is discussed in terms of inhibition of the silver cluster precursors or of dissolution of the laser-induced silver clusters. These results show the ability of laser writing inhibition in our photosensitive silver-containing phosphate glass, which is a necessary step to further develop super-resolution laser writing approaches, such as STED-like DLW, either of fluorescent silver clusters or of silver metallic nanoparticles with plasmonic properties. PMID:26368730

  20. Control scheme for direct steam generation in parabolic troughs under recirculation operation mode

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, L.; Zarza, E. [CIEMAT, Plataforma Solar de Almeria, Ctra. Senes s/n, P.O. Box 22, E-04200 Tabernas, Almeria (Spain); Berenguel, M. [Universidad de Almeria, Dpto. Lenguajes y Computacion, Ctra. Sacramento s/n, E-04120 Almeria (Spain); Camacho, E.F. [Universidad de Sevilla, Dpto. de Ingenieria de Sistemas y Automatica, Camino de los Descubrimientos s/n, E-41092 Sevilla (Spain)

    2006-01-15

    Electricity production using solar thermal energy is one of the main research areas at present in the field of renewable energies, these systems being characterised by the need of reliable control systems aimed at maintaining desired operating conditions in the face of changes in solar radiation, which is the main source of energy. A new prototype of solar system with parabolic trough collectors was implemented at the Plataforma Solar de Almeria (PSA, South-East Spain) to investigate the direct steam generation process under real solar conditions in the parabolic solar collector field of a thermal power plant prototype. This paper presents details and some results of the application of a control scheme designed and tested for the recirculation operation mode, for which the main objective is to obtain steam at constant temperature and pressure at the outlet of the solar field, so that changes produced in the inlet water conditions and/or solar radiation will only affect the amount of steam produced by the solar field. The steam quality and consequently the nominal efficiency of the plant are thus maintained. (author)

  1. A Robust Sensorless Direct Torque Control of Induction Motor Based on MRAS and Extended Kalman Filter

    Directory of Open Access Journals (Sweden)

    Mustapha MESSAOUDI

    2008-06-01

    Full Text Available In this paper, the classical Direct Torque Control (DTC of Induction Motor (IM using an open loop pure integration suffers from the well-known problems of integration especially in the low speed operation range is detailed. To tackle this problem, the IM variables and parameters estimation is performed using a recursive non-linear observer known as EKF. This observer is used to estimate the stator currents, the rotor flux linkages, the rotor speed and the stator resistance. The main drawback of the EKF in this case is that the load dynamics has to be known which is not usually possible. Therefore, a new method based on the Model Reference Adaptive System (MRAS is used to estimate the rotor speed. The two different nonlinear observers applied to sensorless DTC of IM, are discussed and compared to each other. The rotor speed estimation in DTC technique is affected by parameter variations especially the stator resistance due to temperature particularly at low speeds. Therefore, it is necessary to compensate this parameter variation in sensorless induction motor drives using an online adaptation of the control algorithm by the estimated stator resistance. A simulation work leads to the selected results to support the study findings.

  2. Position Servo Control for a Direct-Drive Actuator Based on Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Baifen Liu

    2013-05-01

    Full Text Available A novel position control strategy for a Brushless DC motor (BLDC drive is proposed in this paper. Brushless DC motor, which is widely used in the field of Direct Drive servo Actuator (DDA with superior performance, possesses fast transient response and high accuracy. Nevertheless, there are such uncertainties as unpredictable flow torques and estimated errors of the BLDC model in this system, which may influence the accuracy and the rapid response of the control. So in this paper, genetic algorithm is applied to the position loop. Simultaneously, in order to improve the rapidness of the whole system, position and velocity double closed-loop system is compared with position and current double closed-loop system. Experimental results validate the scheme proposed can attenuate the influences by the uncertainties of the model sharply. The genetic algorithm used in the position loop can ensure the system's stability and the accuracy of the position response. While tracking the same step response the step rise time of the double closed loop structure of the position and current reduced more than 25% compared with that of the double closed loop structure of the position and velocity.

  3. Field plot test of efficacy of thiobencarb formulations for weed control in direct seeded rice

    International Nuclear Information System (INIS)

    Experiments were conducted in field plots in Tanjung Karang rice growing are to study the effect of the timing of application and type of formulation of thiobencarb herbicide on the control of weeds, especially Echinochloa crusgalli. The area selected has a history of heavy weed infestation in farmers fields. In these tests the performance of a commonly used commercial thiobencarb formulation, SaturnR was compared with that of a controlled-release (CR) formulation. These contained 5.0 and 7.56% thiobencarb, respectively. The CR formulation had the herbicide uniformly dispersed in a mixture of calcium alginate and kaolin. The herbicide was applied at 6 and 1 day before direct sowing (DBS) of the rice seeds at 60 kg/ha rate. The herbicide formulations were applied singly or as a 50/50 mixture to deliver 0.75 or 1.50 kg a.i./ha. The effect of the treatments on the number and growth of weed plants, the growth parameters of the rice plants and the rice grain yield was determined. SaturnR at 1.5 kg/ha, CR formulation at 0.75 kg/ha and hand weeding were most effective in controlling the number of E. crusgalli plants. There was no significant difference between the formulations or the rates used regarding their effect on the growth of the rice plants. The highest rice grain yield was recorded from the plots treated with the CR formulation at 1.5 kg/ha. The CR formulation was also very effective at 0.75 kg/ha rate and the rice grain yield was recorded from the plots receiving this treatment was much greater than those treated with a similar rate of the commercial formulation. (author). 5 tabs

  4. Combined Discrete Space Voltage Vector with Direct Torque Control for Bearingless Brushless DC Motor and Closed-Loop Suspended Force Control

    Directory of Open Access Journals (Sweden)

    Weiran Wang

    2013-06-01

    Full Text Available In order to improve the performance of bearingless brushless DC motor, a closed-loop suspended force controller combining the discrete space voltage vector modulation is applied and the direct torque control is presented in this paper. Firstly, we increase the number of the control vector to reduce the torque ripple. Then, the suspending equation is constructed which is spired by the direct torque control algorithm. As a result, the closed-loop suspended force controller is built. The simulated and experimental results evaluate the performance of the proposed method. The more advantage is that the proposed algorithm can achieve the fast torque response, reduce the torque ripple, and follow ideal stator flux track. Furthermore, the motor which implants the closed-loop suspended force controller cannot onlyobtain the dynamic response rapidly and displacement control accurately, but also has the characteristics of bearingless brushless DC motor (such as simple structure, high energy efficiency, small volume and low failure rate.

  5. Effect of candesartan on prevention (DIRECT-Prevent 1) and progression (DIRECT-Protect 1) of retinopathy in type 1 diabetes: randomised, placebo-controlled trials

    DEFF Research Database (Denmark)

    Chaturvedi, N.; Porta, M.; Klein, R.; Orchard, T.; Fuller, J.; Bilous, R.; Sjolie, A.K.; Parving, Hans-Henrik

    2008-01-01

    BACKGROUND: Results of previous studies suggest that renin-angiotensin system blockers might reduce the burden of diabetic retinopathy. We therefore designed the DIabetic REtinopathy Candesartan Trials (DIRECT) Programme to assess whether candesartan could reduce the incidence and progression of...... retinopathy in type 1 diabetes. METHODS: Two randomised, double-blind, parallel-design, placebo-controlled trials were done in 309 centres worldwide. Participants with normotensive, normoalbuminuric type 1 diabetes without retinopathy were recruited to the DIRECT-Prevent 1 trial and those with existing...... retinopathy were recruited to DIRECT-Protect 1, and were assigned to candesartan 16 mg once a day or matching placebo. After 1 month, the dose was doubled to 32 mg. Investigators and participants were unaware of the treatment allocation status. The primary endpoints were incidence and progression of...

  6. Microstructural control during direct laser deposition of a β-titanium alloy

    International Nuclear Information System (INIS)

    Graphical abstract: Microstructural development of Ti5553 during Direct Laser Deposition (DLD). - Highlights: • Good structural and geometrical integrity could be achieved by process design. • Build height increases with decreased scanning speed and increased powder flow rate. • Keeping Z increment close to actual layer thickness is crucial for consistent building. • The laser deposited Ti5553 are dominated by mixed columnar and equiaxed grains. • In situ dwelling and annealing promote α precipitation which improves microhardness. - Abstract: A concern associated with Direct Laser Deposition (DLD) is the difficulty in controlling microstructure due to rapid cooling rates after deposition, particularly in beta-Ti alloys. In these alloys, the beta-phase is likely to exist following DLD, instead of the desirable duplex alpha + beta microstructure that gives a good balance of properties. Thus, in this work, a parametric study was performed to assess the role of DLD parameters on porosity, build geometry, and microstructure in a beta-Ti alloy, Ti–5Al–5Mo–5V–3Cr (Ti5553). The builds were examined using optical microscopy, scanning electron microscopy, and X-ray diffraction. Microhardness measurements were performed to assess the degree of re-precipitation of alpha-phase following an in situ dwelling and laser annealing procedure. The study identified several processing conditions that enable deposition of samples with the desired geometry and low porosity level. The microstructure was dominated by beta-phase, except for the region near the substrate where a limited amount of alpha-precipitates was present due to reheating effect. Although the microstructure was a mixture of equiaxed and columnar beta-grains alongside infrequent fine alpha-precipitates, the builds showed fairly uniform microhardness in different regions. In situ dwelling and annealing did not cause an obvious change in porosity, but did promote the formation of alpha-precipitates

  7. Use of Controlled Release Fertilizer for Increasing N Efficiency of Direct Seeding Rice

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Field trials on a silt-loamy paddy soil derived from shallow-sea deposit in direct seeding rice fields were conducted in Zhejiang, China, in 1996 to compare N efficiency of controlled release fertilizers (LP fertilizers) with the conventional urea. Six treatments including CK (no N fertilizer), conventional urea and different types of LP fertilizers at different rates were designed for two succeeding crops of early and late rice. A blend of different types of LP fertilizers as a single preplant "co-situs" application released N in a rate and amount synchronizing with uptake pattern of direct seeding rice. A single preplant application of the LP fertilizers could meet the N requirement of rice for the whole growth period without need of topdressing. Using LP fertilizer blends, equivalent grain yields could be maintained even if the N fertilization rates were reduced by 25%~50% compared with the conventional urea. Agronomic efficiency of the LP fertilizers was 13.6%~86.4% higher than that of the conventional urea in early rice and 100%~164.1% in late rice, depending on the amounts of the LP fertilizers applied. N fertilizer recovery rate increased from 27.4% for the conventional application of urea to 41.7%~54.1% for the single preplant "co-situs" application of the LP fertilizers. Use of the LP fertilizers was promising if the increase in production costs due to the high LP fertilizer prices could be compensated by increase in yield and N efficiency, reduction in labor costs and improvement in environment.

  8. Combined Flux Observer With Signal Injection Enhancement for Wide Speed Range Sensorless Direct Torque Control of IPMSM Drives

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Andreescu, G.-D.; Pitic, C.I.;

    2008-01-01

    This paper proposes a motion-sensorless control system using direct torque control with space vector modulation for interior permanent magnet synchronous motor (IPMSM) drives, for wide speed range operation, including standstill. A novel stator flux observer with variable structure uses a combined...

  9. High Performance of Space Vector Modulation Direct Torque Control SVM-DTC Based on Amplitude Voltage and Stator Flux Angle

    Directory of Open Access Journals (Sweden)

    Hassan Farhan Rashag

    2013-04-01

    Full Text Available Various aspects related to controlling induction motor are investigated. Direct torque control is an original high performance control strategy in the field of AC drive. In this proposed method, the control system is based on Space Vector Modulation (SVM, amplitude of voltage in direct- quadrature reference frame (d-q reference and angle of stator flux. Amplitude of stator voltage is controlled by PI torque and PI flux controller. The stator flux angle is adjusted by rotor angular frequency and slip angular frequency. Then, the reference torque and the estimated torque is applied to the input of PI torque controller and the control quadrature axis voltage is determined. The control d-axis voltage is determined from the flux calculator. These q and d axis voltage are converted into amplitude voltage. By applying polar to Cartesian on amplitude voltage and stator flux angle, direct voltage and quadratures voltage are generated. The reference stator voltages in d-q are calculated based on forcing the stator voltage error to zero at next sampling period. By applying inverse park transformation on d-q voltages, the stator voltages in &alpha and &beta frame are generated and apply to SVM. From the output of SVM, the motor control signal is generated and the speed of the induction motor regulated toward the rated speed. The simulation Results have demonstrated exceptional performance in steady and transient states and shows that decrease of torque and flux ripples is achieved in a complete speed range.

  10. A Novel Direct Torque Control for Induction Machine Drive System with Low Torque And Flux Ripples using XSG

    Directory of Open Access Journals (Sweden)

    Souha Boukadida

    2014-12-01

    Full Text Available The conventional Direct Torque Control (DTC is known to produce a quick and robust response in AC drives. However, during steady state, stator flux and electromagnetic torque which results in incorrect speed estimations and acoustical noise. A modified Direct Torque Control (DTC by using Space Vector Modulation (DTC-SVM for induction machine is proposed in this paper. Using this control strategy, the ripples introduced in torque and flux are reduced. This paper presents a novel approach to design and implementation of a high perfromane torque control (DTC-SVM of induction machine using Field Programmable gate array (FPGA.The performance of the proposed control scheme is evaluated through digital simulation using Matlab\\Simulink and Xilinx System Generator. The simulation results are used to verify the effectiveness of the proposed control strategy.

  11. A comparative study of field-oriented control and direct-torque control of induction motors using an adaptive flux observer

    Directory of Open Access Journals (Sweden)

    Chikhi Abdesselam

    2010-01-01

    Full Text Available This paper presents a comparative study of field-oriented control (IFOC and direct-torque control (DTC of induction motors using an adaptive flux observer. The main characteristics of field-oriented control and direct torque control schemes are studied by simulation, emphasizing their advantages and disadvantages. The performances of the two control schemes are evaluated in terms of torque, current ripples and transient responses to load toque variations. We can nevertheless observe a slight advance of DTC scheme compared to FOC scheme regarding the dynamic flux control performance and the implementation complexity. Consequently, the choice of one or the other scheme will depend mainly on specific requirements of the application.

  12. Effects of Anodal Transcranial Direct Current Stimulation on Visually Guided Learning of Grip Force Control

    Directory of Open Access Journals (Sweden)

    Tamas Minarik

    2015-03-01

    Full Text Available Anodal transcranial Direct Current Stimulation (tDCS has been shown to be an effective non-invasive brain stimulation method for improving cognitive and motor functioning in patients with neurological deficits. tDCS over motor cortex (M1, for instance, facilitates motor learning in stroke patients. However, the literature on anodal tDCS effects on motor learning in healthy participants is inconclusive, and the effects of tDCS on visuo-motor integration are not well understood. In the present study we examined whether tDCS over the contralateral motor cortex enhances learning of grip-force output in a visually guided feedback task in young and neurologically healthy volunteers. Twenty minutes of 1 mA anodal tDCS were applied over the primary motor cortex (M1 contralateral to the dominant (right hand, during the first half of a 40 min power-grip task. This task required the control of a visual signal by modulating the strength of the power-grip for six seconds per trial. Each participant completed a two-session sham-controlled crossover protocol. The stimulation conditions were counterbalanced across participants and the sessions were one week apart. Performance measures comprised time-on-target and target-deviation, and were calculated for the periods of stimulation (or sham and during the afterphase respectively. Statistical analyses revealed significant performance improvements over the stimulation and the afterphase, but this learning effect was not modulated by tDCS condition. This suggests that the form of visuomotor learning taking place in the present task was not sensitive to neurostimulation. These null effects, together with similar reports for other types of motor tasks, lead to the proposition that tDCS facilitation of motor learning might be restricted to cases or situations where the motor system is challenged, such as motor deficits, advanced age, or very high task demand.

  13. Terminalia gum as a directly compressible excipient for controlled drug delivery.

    Science.gov (United States)

    Bamiro, Oluyemisi A; Odeku, Oluwatoyin A; Sinha, Vivek R; Kumar, Ruchita

    2012-03-01

    The exudates from the incised trunk of Terminalia randii has been evaluated as controlled release excipient in comparison with xanthan gum and hydroxypropylmethylcellulose (HPMC) using carvedilol (water insoluble) and theophylline (water soluble) as model drugs. Matrix tablets were prepared by direct compression and the effects of polymer concentration and excipients-spray dried lactose, microcrystalline cellulose and dicalcium phosphate dihydrate on the mechanical (crushing strength (CS) friability (F) and crushing strength-friability ratio (CSFR)) and drug release properties of the matrix tablets were evaluated. The drug release data were fitted into different release kinetics equations to determine the drug release mechanism(s) from the matrix tablets. The results showed that the CS and CSFR increased with increase in polymer concentration while F decreased. The ranking of CS and CSFR was HPMC > terminalia > xanthan while the ranking was reverse for F. The ranking for t(25) (i.e. time for 25% drug release) at a polymer concentration of 60% was xanthan > terminalia = HPMC. The dissolution time, t(25), of theophylline matrices was significantly lower (p < 0.001) than those of carvedilol matrix tablets. Drug release from the matrices was by swelling, diffusion and erosion. The mechanical and drug release properties of the tablets were significantly (p < 0.05) dependent on the type and concentration of polymer and excipients used with the release mechanisms varying from Fickian to anomalous. Terminalia gum compared favourably with standard polymers when used in controlled release matrices and could serve as a suitable alternative to the standard polymers in drug delivery. PMID:22068290

  14. Reducing heliostat field costs by direct measurement and control of the mirror orientation

    Science.gov (United States)

    van den Donker, P.; Rosinga, G.; van Voorthuysen, E. du Marchie

    2016-05-01

    The first commercial CSP Central Receiver System has been in operation since 2007. The technology required for such a central receiver system is quite new. The determining factor of the price of electricity is the capital investment in the heliostat field. The cost level per square meter of the heliostat field is rather high. Sun2point is questioning the market development, which is trying to get the cost level down by aiming at large heliostats. Sun2Point aims at mass manufacturing small heliostats to achieve low prices. Mass manufacturing off-site and transport over long distances is possible for small heliostats only. Calibration on the spot is a labour-intensive activity. Autonomous, factory calibrated and wireless controlled heliostats are the solution to lower installation cost. A new measurement method that directly reports the orientation of the heliostat in relation to the earth and the sun can solve the calibration problem when the heliostats are installed. The application of small heliostats will be much cheaper as a result of this measurement method. In this paper several methods for such a measurement are described briefly. The new Sun2Point method has successfully been tested. In this paper Sun2Point challenges the CSP community to investigate this approach. A brief survey is presented of many aspects that lead to a low price.

  15. A very fast direct torque control for interior permanent magnet synchronous motors start up

    Energy Technology Data Exchange (ETDEWEB)

    Ghassemi, H.; Vaez-Zadeh, S. [University of Tehran (Iran). Faculty of Engineering

    2005-03-01

    Selection of the stator flux command in direct torque control (DTC) of permanent magnet synchronous motors is very important as it affects machine performance. For steady state operation, it can help to decrease the stator current or machine losses. However, in order to get a fast torque response during motor start up, one needs to change both the stator flux angle and magnitude. In this paper, a method is presented to find the optimal voltage vectors to change both the flux angle and its magnitude that results in high-speed dynamics for the torque response. The closed form formula given for the optimal voltage vector is derived based on maximizing the torque change in each sampling time. The simulation results show that the presented method is superior to the conventional DTC. In other words, it is shown that the voltage vectors derived from the switching table for conventional DTC are not the optimal voltage vectors for the situation in which there is a step change in the torque command. (author)

  16. Control of plasma properties in a short direct-current glow discharge with active boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S. F. [Air Force Research Laboratory, WPAFB, Ohio 45433 (United States); Demidov, V. I., E-mail: vladimir.demidov@mail.wvu.edu [Air Force Research Laboratory, WPAFB, Ohio 45433 (United States); West Virginia University, Morgantown, West Virginia 26506 (United States); Bogdanov, E. A.; Kudryavtsev, A. A. [St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Koepke, M. E. [West Virginia University, Morgantown, West Virginia 26506 (United States); Kurlyandskaya, I. P. [St. Petersburg University of State Fire Service of EMERCOM RF, Murmansk Branch, Murmansk 183040 (Russian Federation)

    2016-02-15

    To demonstrate controlling electron/metastable density ratio and electron temperature by applying negative voltages to the active (conducting) discharge wall in a low-pressure plasma with nonlocal electron energy distribution function, modeling has been performed in a short (lacking the positive-column region) direct-current glow discharge with a cold cathode. The applied negative voltage can modify the trapping of the low-energy part of the energetic electrons that are emitted from the cathode sheath and that arise from the atomic and molecular processes in the plasma within the device volume. These electrons are responsible for heating the slow, thermal electrons, while production of slow electrons (ions) and metastable atoms is mostly due to the energetic electrons with higher energies. Increasing electron temperature results in increasing decay rate of slow, thermal electrons (ions), while decay rate of metastable atoms and production rates of slow electrons (ions) and metastable atoms practically are unchanged. The result is in the variation of electron/metastable density ratio and electron temperature with the variation of the wall negative voltage.

  17. Discharge measurement with salt dilution method in irrigation canals: direct sampling and geophysical controls

    Directory of Open Access Journals (Sweden)

    C. Comina

    2013-08-01

    Full Text Available An important starting point for designing management improvements, particularly in irrigation areas, is to record the baseline state of the water resources, including the amount of discharge from canals. In this respect discharge measurements by means of the salt dilution method is a traditional and well-documented technique. However, this methodology can be strongly influenced by the natural streaming characteristics of the canal (e.g. laminar vs. turbulent flow and accurate precautions must be considered in the choice of both the measuring section and the length of the measuring reach of the canal which can affect the plume shape. The knowledge of plume distribution in the measuring cross-section is of primary importance for a correct location of sampling points aimed in obtaining a reliable measurement. To obtain this, geophysical imaging of an NaCl plume from a slug-injection salt dilution test has been performed within this paper by means of cross-flow fast electric resistivity tomography (FERT in a real case history. Direct sampling of the same plume has been also performed with a multisampling optimization technique to obtain an average value over the measuring section by means of contemporarily sampling water in nine points. Results show that a correct visualization of the passage of the salt plume is possible by means of geophysical controls and that this can potentially help in the correct location of sampling points.

  18. The Development of an UAV Borne Direct Georeferenced Photogrammetric Platform for Ground Control Point Free Applications

    Directory of Open Access Journals (Sweden)

    Chien-Hsun Chu

    2012-07-01

    Full Text Available To facilitate applications such as environment detection or disaster monitoring, the development of rapid low cost systems for collecting near real time spatial information is very critical. Rapid spatial information collection has become an emerging trend for remote sensing and mapping applications. In this study, a fixed-wing Unmanned Aerial Vehicle (UAV-based spatial information acquisition platform that can operate in Ground Control Point (GCP free environments is developed and evaluated. The proposed UAV based photogrammetric platform has a Direct Georeferencing (DG module that includes a low cost Micro Electro Mechanical Systems (MEMS Inertial Navigation System (INS/ Global Positioning System (GPS integrated system. The DG module is able to provide GPS single frequency carrier phase measurements for differential processing to obtain sufficient positioning accuracy. All necessary calibration procedures are implemented. Ultimately, a flight test is performed to verify the positioning accuracy in DG mode without using GCPs. The preliminary results of positioning accuracy in DG mode illustrate that horizontal positioning accuracies in the x and y axes are around 5 m at 300 m flight height above the ground. The positioning accuracy of the z axis is below 10 m. Therefore, the proposed platform is relatively safe and inexpensive for collecting critical spatial information for urgent response such as disaster relief and assessment applications where GCPs are not available.

  19. Direct Adaptive Tracking Control for a Class of Pure-Feedback Stochastic Nonlinear Systems Based on Fuzzy-Approximation

    Directory of Open Access Journals (Sweden)

    Huanqing Wang

    2014-01-01

    Full Text Available The problem of fuzzy-based direct adaptive tracking control is considered for a class of pure-feedback stochastic nonlinear systems. During the controller design, fuzzy logic systems are used to approximate the packaged unknown nonlinearities, and then a novel direct adaptive controller is constructed via backstepping technique. It is shown that the proposed controller guarantees that all the signals in the closed-loop system are bounded in probability and the tracking error eventually converges to a small neighborhood around the origin in the sense of mean quartic value. The main advantages lie in that the proposed controller structure is simpler and only one adaptive parameter needs to be updated online. Simulation results are used to illustrate the effectiveness of the proposed approach.

  20. Engineered Tug-of-War Between Kinesin and Dynein Controls Direction of Microtubule Based Transport In Vivo.

    Science.gov (United States)

    Rezaul, Karim; Gupta, Dipika; Semenova, Irina; Ikeda, Kazuho; Kraikivski, Pavel; Yu, Ji; Cowan, Ann; Zaliapin, Ilya; Rodionov, Vladimir

    2016-05-01

    Bidirectional transport of membrane organelles along microtubules (MTs) is driven by plus-end directed kinesins and minus-end directed dynein bound to the same cargo. Activities of opposing MT motors produce bidirectional movement of membrane organelles and cytoplasmic particles along MT transport tracks. Directionality of MT-based transport might be controlled by a protein complex that determines which motor type is active at any given moment of time, or determined by the outcome of a tug-of-war between MT motors dragging cargo organelles in opposite directions. However, evidence in support of each mechanisms of regulation is based mostly on the results of theoretical analyses or indirect experimental data. Here, we test whether the direction of movement of membrane organelles in vivo can be controlled by the tug-of-war between opposing MT motors alone, by attaching a large number of kinesin-1 motors to organelles transported by dynein to minus-ends of MTs. We find that recruitment of kinesin significantly reduces the length and velocity of minus-end-directed dynein-dependent MT runs, leading to a reversal of the overall direction of dynein-driven organelles in vivo. Therefore, in the absence of external regulators tug-of-war between opposing MT motors alone is sufficient to determine the directionality of MT transport in vivo. PMID:26843027

  1. Direct Methods for Predicting Movement Biomechanics Based Upon Optimal Control Theory with Implementation in OpenSim.

    Science.gov (United States)

    Porsa, Sina; Lin, Yi-Chung; Pandy, Marcus G

    2016-08-01

    The aim of this study was to compare the computational performances of two direct methods for solving large-scale, nonlinear, optimal control problems in human movement. Direct shooting and direct collocation were implemented on an 8-segment, 48-muscle model of the body (24 muscles on each side) to compute the optimal control solution for maximum-height jumping. Both algorithms were executed on a freely-available musculoskeletal modeling platform called OpenSim. Direct collocation converged to essentially the same optimal solution up to 249 times faster than direct shooting when the same initial guess was assumed (3.4 h of CPU time for direct collocation vs. 35.3 days for direct shooting). The model predictions were in good agreement with the time histories of joint angles, ground reaction forces and muscle activation patterns measured for subjects jumping to their maximum achievable heights. Both methods converged to essentially the same solution when started from the same initial guess, but computation time was sensitive to the initial guess assumed. Direct collocation demonstrates exceptional computational performance and is well suited to performing predictive simulations of movement using large-scale musculoskeletal models. PMID:26715209

  2. Feasibility of optimizing trimetazidine dihydrochloride release from controlled porosity osmotic pump tablets of directly compressed cores.

    Science.gov (United States)

    Habib, Basant A; Rehim, Randa T Abd El; Nour, Samia A

    2014-05-01

    The aim of this study was to develop and optimize Trimetazidine dihydrochloride (TM) controlled porosity osmotic pump (CPOP) tablets of directly compressed cores. A 2(3) full factorial design was used to study the influence of three factors namely: PEG400 (10% and 25% based on coating polymer weight), coating level (10% and 20% of tablet core weight) and hole diameter (0 "no hole" and 1 mm). Other variables such as tablet cores, coating mixture of ethylcellulose (4%) and dibutylphthalate (2%) in 95% ethanol and pan coating conditions were kept constant. The responses studied (Yi ) were cumulative percentage released after 2 h (Q%2h), 6 h (Q%6h), 12 h (Q%12h) and regression coefficient of release data fitted to zero order equation (RSQzero), for Y 1, Y 2, Y 3, and Y 4, respectively. Polynomial equations were used to study the influence of different factors on each response individually. Response surface methodology and multiple response optimization were used to search for an optimized formula. Response variables for the optimized formula were restricted to 10% ⩽ Y 1 ⩽ 20%, 40% ⩽ Y 2 ⩽ 60%, 80% ⩽ Y 3 ⩽ 100%, and Y 4 > 0.9. The statistical analysis of the results revealed that PEG400 had positive effects on Q%2h, Q%6h and Q%12h, hole diameter had positive effects on all responses and coating level had positive effect on Q%6h, Q%12h and negative effect on RSQzero. Full three factor interaction (3FI) equations were used for representation of all responses except Q%2h which was represented by reduced (3FI) equation. Upon exploring the experimental space, no formula in the tested range could satisfy the required constraints. Thus, direct compression of TM cores was not suitable for formation of CPOP tablets. Preliminary trials of CPOP tablets with wet granulated cores were promising with an intact membrane for 12 h and high RSQzero. Further improvement of these formulations to optimize TM release will be done in further studies. PMID

  3. Robust Non-Linear Direct Torque and Flux Control of Adjustable Speed Sensorless PMSM Drive Based on SVM Using a PI Predictive Controller

    Directory of Open Access Journals (Sweden)

    F. Naceri

    2010-01-01

    Full Text Available This paper presents a new sensorless direct torque control method for voltage inverter – fed PMSM. The control methodis used a modified Direct Torque Control scheme with constant inverter switching frequency using Space Vector Modulation(DTC-SVM. The variation of stator and rotor resistance due to changes in temperature or frequency deteriorates theperformance of DTC-SVM controller by introducing errors in the estimated flux linkage and the electromagnetic torque.As a result, this approach will not be suitable for high power drives such as those used in tractions, as they require goodtorque control performance at considerably lower frequency. A novel stator resistance estimator is proposed. The estimationmethod is implemented using the Extended Kalman Filter. Finally extensive simulation results are presented to validate theproposed technique. The system is tested at different speeds and a very satisfactory performance has been achieved.

  4. Direct Adaptive Fuzzy Sliding Mode Control with Variable Universe Fuzzy Switching Term for a Class of MIMO Nonlinear Systems

    Directory of Open Access Journals (Sweden)

    Guo Haigang

    2012-01-01

    Full Text Available Combining adaptive fuzzy sliding mode control with fuzzy or variable universe fuzzy switching technique, this study develops two novel direct adaptive schemes for a class of MIMO nonlinear systems with uncertainties and external disturbances. The proposed control schemes consist of fuzzy equivalent control terms, fuzzy switching control terms (in scheme one or variable universe fuzzy switching control terms (in scheme two, and compensation control terms. The compensation control terms are used to relax the assumption on fuzzy approximation error. Based on Lyapunov stability theory, the parameters update laws are adaptively tuned online and the global asymptotic stability of the closed-loop system can be guaranteed. The major contribution of this study is to develop a novel framework for designing direct adaptive fuzzy sliding mode control scheme facing model uncertainties and external disturbances. The derived schemes can effectively solve the chattering problem and the equivalent control calculation in that environment. Simulation results performed on a two-link robotic manipulator demonstrate the feasibility of the proposed control schemes.

  5. Control of a Two-Stage Direct Power Converter with a Single Voltage Sensor Mounted in the Intermediary Circuit

    DEFF Research Database (Denmark)

    Klumpner, Christian; Wheeler, P.; Blaabjerg, Frede

    2004-01-01

    Controlling a converter requires not only a powerful processors but also accurate voltage and current sensors and fast and precise analogue-digital converters, which increase the cost per kW of the assembly, especially in the low power range. A matrix converter requires less transducers than a back......-to-back Voltage Source Converter because of the inherent direct power transfer which doesn?t require a control loop of the dc-link voltage to balance the power of the rectifier and the inverter. On the other hand, two-stage Direct Power Converters (DPC) also perform direct power conversion as the matrix...... converters but in two stages (AC/DC/AC) without using energy storage in the intermediary circuit. They also offer the possibility to reduce the number of switches compared to the standard single-stage matrix converter. This paper presents a new method to control a two-stage DPC providing sine-wave in sine...

  6. Diagnostic Assessment of the Difficulty Using Direct Policy Search in Many-Objective Reservoir Control

    Science.gov (United States)

    Zatarain-Salazar, J.; Reed, P. M.; Herman, J. D.; Giuliani, M.; Castelletti, A.

    2014-12-01

    Globally reservoir operations provide fundamental services to water supply, energy generation, recreation, and ecosystems. The pressures of expanding populations, climate change, and increased energy demands are motivating a significant investment in re-operationalizing existing reservoirs or defining operations for new reservoirs. Recent work has highlighted the potential benefits of exploiting recent advances in many-objective optimization and direct policy search (DPS) to aid in addressing these systems' multi-sector demand tradeoffs. This study contributes to a comprehensive diagnostic assessment of multi-objective evolutionary optimization algorithms (MOEAs) efficiency, effectiveness, reliability, and controllability when supporting DPS for the Conowingo dam in the Lower Susquehanna River Basin. The Lower Susquehanna River is an interstate water body that has been subject to intensive water management efforts due to the system's competing demands from urban water supply, atomic power plant cooling, hydropower production, and federally regulated environmental flows. Seven benchmark and state-of-the-art MOEAs are tested on deterministic and stochastic instances of the Susquehanna test case. In the deterministic formulation, the operating objectives are evaluated over the historical realization of the hydroclimatic variables (i.e., inflows and evaporation rates). In the stochastic formulation, the same objectives are instead evaluated over an ensemble of stochastic inflows and evaporation rates realizations. The algorithms are evaluated in their ability to support DPS in discovering reservoir operations that compose the tradeoffs for six multi-sector performance objectives with thirty-two decision variables. Our diagnostic results highlight that many-objective DPS is very challenging for modern MOEAs and that epsilon dominance is critical for attaining high levels of performance. Epsilon dominance algorithms epsilon-MOEA, epsilon-NSGAII and the auto adaptive Borg

  7. Transcranial direct current stimulation improves seizure control in patients with Rasmussen encephalitis.

    Science.gov (United States)

    Tekturk, Pinar; Erdogan, Ezgi Tuna; Kurt, Adnan; Kocagoncu, Ece; Kucuk, Zeynep; Kinay, Demet; Yapici, Zuhal; Aksu, Serkan; Baykan, Betul; Karamursel, Sacit

    2016-03-01

    Rasmussen encephalitis is associated with severe seizures that are unresponsive to antiepileptic drugs, as well as immunosuppressants. Transcranial direct current stimulation (t-DCS) is a non-invasive and safe method tried mostly for focal epilepsies with different aetiologies. To date, there is only one published study with two case reports describing the effect of t-DCS in Rasmussen encephalitis. Our aim was to investigate the effect of t-DCS on seizures in Rasmussen encephalitis and to clarify its safety. Five patients (mean age: 19; three females), diagnosed with Rasmussen encephalitis were included in this study. Patients received first cathodal, then anodal (2 mA for 30 minutes on three consecutive days for non-sham stimulations), and finally sham stimulation with two-month intervals, respectively. Three patients received classic (DC) cathodal t-DCS whereas two patients received cathodal stimulation with amplitude modulation at 12 Hz. Afterwards, all patients received anodal stimulation with amplitude modulation at 12 Hz. In the last part of the trial, sham stimulation (a 60-second stimulation with gradually decreasing amplitude to zero in the last 15 seconds) was applied to three patients. Maximum current density was 571 mA/m2 using 70 mm x 50 mm wet sponge electrodes with 2-mA maximum, current controlled stimulator, and maximum charge density was 1028 C/m2 for a 30-minute stimulation period. After cathodal stimulation, all but one patient had a greater than 50% decrease in seizure frequency. Two patients who received modulated cathodal t-DCS had better results. The longest positive effect lasted for one month. A second trial with modulated anodal stimulation and a third with sham stimulation were not effective. No adverse effect was reported with all types of stimulations. Both classic and modulated cathodal t-DCS may be suitable alternative methods for improving seizure outcome in Rasmussen encephalitis patients. PMID:26842560

  8. The ribosome structure controls and directs mRNA entry, translocation and exit dynamics

    International Nuclear Information System (INIS)

    The protein-synthesizing ribosome undergoes large motions to effect the translocation of tRNAs and mRNA; here, the domain motions of this system are explored with a coarse-grained elastic network model using normal mode analysis. Crystal structures are used to construct various model systems of the 70S complex with/without tRNA, elongation factor Tu and the ribosomal proteins. Computed motions reveal the well-known ratchet-like rotational motion of the large subunits, as well as the head rotation of the small subunit and the high flexibility of the L1 and L7/L12 stalks, even in the absence of ribosomal proteins. This result indicates that these experimentally observed motions during translocation are inherently controlled by the ribosomal shape and only partially dependent upon GTP hydrolysis. Normal mode analysis further reveals the mobility of A- and P-tRNAs to increase in the absence of the E-tRNA. In addition, the dynamics of the E-tRNA is affected by the absence of the ribosomal protein L1. The mRNA in the entrance tunnel interacts directly with helicase proteins S3 and S4, which constrain the mRNA in a clamp-like fashion, as well as with protein S5, which likely orients the mRNA to ensure correct translation. The ribosomal proteins S7, S11 and S18 may also be involved in assuring translation fidelity by constraining the mRNA at the exit site of the channel. The mRNA also interacts with the 16S 3' end forming the Shine–Dalgarno complex at the initiation step; the 3' end may act as a 'hook' to reel in the mRNA to facilitate its exit

  9. Comparison of Current Control Strategies Applied to a Boost-Rectifier Connected to a Direct Drive Wave Energy Converter

    OpenAIRE

    Rocha Mendonca, Hugo; Martínez González, Sergio; Ramírez Prieto, Dionisio

    2015-01-01

    Direct drive wave energy converters are characterized by a direct conversion of the wave energy into electricity with no intermediate mechanical conversion system. For this reason, optimization methods for maximizing the absorbed power have to be designed for acting on the electrical generator. Besides, this type of system requires power electronics to be connected to the grid. This paper evaluates three different current control strategies applied to a boost-rectifier in the ac-dc stage as p...

  10. Improvement of Torque Response and Reduction of Error Speed in Direct Torque Control of Induction Motor by Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    HamidReza Fakharizadeh

    2009-09-01

    Full Text Available In this paper, the direct torque control (DTC technique is used for the speed control of induction motors, and then fuzzy logic is used for designing the speed controller, the improvement of torque response and the reduction of the speed error. The DTC method is utilized due to its quick torque response and robustness against sudden load variations. Also, by applying fuzzy logic unpredicted problems can be solved. The fuzzy logic also can improve the work of the speed control in induction motors. The results indicate that this approach improves the torque response significantly and reduces speed error.

  11. Speed Sensorless Direct Rotor Field-Oriented Control of Single-Phase Induction Motor Using Extended Kalman Filter

    Directory of Open Access Journals (Sweden)

    Mohammad Jannati

    2014-12-01

    Full Text Available Nowadays, Field-Oriented Control (FOC strategies broadly used as a vector based controller for Single-Phase Induction Motors (SPIMs. This paper is focused on Direct Rotor FOC (DRFOC of SPIM. In the proposed technique, transformation matrices are applied in order to control the motor by converting the unbalanced SPIM equations to the balanced equations (in this paper the SPIM with two different stator windings is considered. Besides this control technique, a method for speed estimation of SPIM based on Extended Kalman Filter (EKF to achieve the higher performance of SPIM drive system is presented. Simulation results are provided to demonstrate the high performance of the presented techniques.

  12. Optimal state feedback control of brushless direct-current motor drive systems based on Lyapunov stability criterion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper develops a unified methodology for a real-time speed control of brushless direct-current motor drive systems in the presence of measurement noise and load torque disturbance. First, the mathematical model and hardware structure of system is established. Next, an optimal state feed back controller using the Kalman filter state estimation technique is derived.This is followed by an adaptive control algorithm to compensate for the effects of noise and disturbance. Those two algorithms working together can provide a very-high-speed regulation and dynamic response over a wide range of operating conditions.Simulated responses are presented to highlight the effectiveness of the proposed control strategy.

  13. Direct Torque Control Algorithm for Induction Motor Using Hybrid Fuzzy-PI and Anti-Windup PI Controller with DC Current Sensors

    Directory of Open Access Journals (Sweden)

    Anju R

    2014-03-01

    Full Text Available In this paper, torque ripple minimization in direct torque control (DTC of three phase Induction Motor (IM using PI, hybrid fuzzy PI and anti-windup PI controller were compared. Speed performance is also improved when the controllers were changed. Reconstruction of phase current method is used in the conventional method, by using this method cost of the sensors is reduced and also basic DTC performance is maintained. The reference speed is used for generating the reference torque with the help of PI controller. The drawback is torque ripple in induction motor by using the existing DTC. In proposed system, controller of hybrid fuzzy-PI and anti-windup PI were implemented for generating the reference torque. The speed performance is improved by hybrid Fuzzy-PI controller and the torque ripples will be minimized by using the anti-windup PI controller. The proposed method is implemented using MATLAB/SIMULINK.

  14. Control of Canadian once-through direct cycle supercritical water-cooled reactors

    International Nuclear Information System (INIS)

    Highlights: • Dynamic characteristics of Canadian SCWR are analyzed. • Hybrid feedforward and feedback control is adopted to deal with cross-coupling. • Gain scheduling control with smooth weight is applied to deal with nonlinearity. • It demonstrates through simulation that the control requirements are satisfied. - Abstract: Canadian supercritical water-cooled reactor (SCWR) can be modelled as a Multiple-input Multiple-output (MIMO) system. It has a high power-to-flow ratio, strong cross-coupling and high degree of nonlinearity in its dynamic characteristics. Among the outputs, the steam temperature is strongly affected by the reactor power and the most challenging to control. It is difficult to adopt a traditional control system design methodology to obtain a control system with satisfactory performance. In this paper, feedforward control is applied to reduce the effect on steam temperature from the reactor power. Single-input Single-output (SISO) feedback controllers are synthesized in the frequency domain. Using the feedforward controller, the steam temperature variation due to disturbances at the reactor power has been significantly suppressed. The control system can effectively maintain the overall system stability and regulate the plant around a specified operating condition. To deal with the nonlinearities, gain scheduling control strategy is adopted. Different sets of controllers combined by smooth weight functions are used for the plant at different load conditions. The proposed control strategies have been evaluated under various operating scenarios. Simulation results show that satisfactory performance can successfully achieved by the designed control system

  15. Design and implementation of high performance direct power control of three-phase PWM rectifier, via fuzzy and PI controller for output voltage regulation

    International Nuclear Information System (INIS)

    This paper proposes direct power control (DPC) for three-phase PWM rectifiers using a new switching table, without line voltage sensors. The instantaneous active and reactive powers, directly controlled by selecting the optimum state of the converter, are used as the PWM control variables instead of the phase line currents being used. The main goal of the control system is to maintain the dc-bus voltage at the required level, while input currents drawn from the power supply should be sinusoidal and in phase with respective phase voltages to satisfy the unity power factor (UPF) operation. Conventional PI and a designed fuzzy logic-based controller, in the dc-bus voltage control loop, have been used to provide active power command. A dSPACE based experimental system was developed to verify the validity of the proposed DPC. The steady-state, and dynamic results illustrating the operation and performance of the proposed control scheme are presented. As a result, it was confirmed that the novel DPC is much better than the classical one. Line currents very close to sinusoidal waveforms (THD < 2%) and good regulation of dc-bus voltage are achieved using PI or fuzzy controller. Moreover, fuzzy logic controller gives excellent performance in transient state, a good rejection of impact load disturbance, and a good robustness

  16. A bi-directional DC/DC converter for hybrid wind generator/battery system with state machine control

    Energy Technology Data Exchange (ETDEWEB)

    Hua, C.C.; Liao, Y.C. [National Yunlin Univ. of Science and Technology, Yunlin, Taiwan (China). Dept. of Electrical Engineering

    2008-07-01

    A bi-directional DC to DC converter used in a hybrid wind generator/lead-acid battery power system was presented. A state machine control strategy was used to control both the system power flow and load distribution. It was also used to increase the power capacity of the system. The battery was also charged or discharged through the bi-directional DC to DC converter. Multi-stage current charging control of the batteries was accomplished by adjusting the duty cycle of the power converter. This also improved the charging efficiency by the maximum power point tracking algorithm. It was concluded that the proposed control method can be readily extended to other renewable energy conversion systems. 6 refs., 13 figs.

  17. Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems

    DEFF Research Database (Denmark)

    Preindl, Matthias; Schaltz, Erik

    2010-01-01

    In drive systems the most used control structure is the cascade control with an inner torque, i.e. current and an outer speed control loop. The fairly small converter switching frequency in high power applications, e.g. wind turbines lead to modest speed control performance. An improvement bring...... dynamic behaviour. It compensates the load torque influence on the speed control setting a feed forward torque value, i.e. current reference value. The benefits are twice. The speed controller reaches immediately the speed reference value avoiding offsets which must be compensated by the weak integrator...

  18. Modified Direct Torque Control of Three-Phase Induction Motor Drives with Low Ripple in Flux and Torque

    OpenAIRE

    Kumar, Vinay; Rao, Srinivasa

    2011-01-01

    This paper proposes an algorithm for direct flux and torque controlled three phase induction motor drive systems. This method is based on control of slip speed and decoupled between amplitude and angle of reference stator flux for determining required stator voltage vector. In this proposes model, integrator unit is not required to generate the reference stator flux angle for calculating required stator voltage vector, hence it eliminates the initial values problems in real time. Within the g...

  19. Modeling and Control of High-Voltage Direct-Current Transmission Systems: From Theory to Practice and Back

    OpenAIRE

    Zonetti, Daniele; Ortega, Romeo; Benchaib, Abdelkrim

    2014-01-01

    The problem of modeling and control of multi-terminal high-voltage direct-current transmission systems is addressed in this paper, which contains five main contributions. First, to propose a unified, physically motivated, modeling framework - based on port-Hamiltonian representations - of the various network topologies used in this application. Second, to prove that the system can be globally asymptotically stabilized with a decentralized PI control, that exploits its passivity properties. Cl...

  20. Energy-Regenerative Braking Control of Electric Vehicles Using Three-Phase Brushless Direct-Current Motors

    OpenAIRE

    Bo Long; Shin Teak Lim; Ji Hyoung Ryu; Kil To Chong

    2013-01-01

    Regenerative braking provides an effective way of extending the driving range of battery powered electric vehicles (EVs). This paper analyzes the equivalent power circuit and operation principles of an EV using regenerative braking control technology. During the braking period, the switching sequence of the power converter is controlled to inverse the output torque of the three-phase brushless direct-current (DC) motor, so that the braking energy can be returned to the battery. Compared with ...

  1. Type-1 and Type-2 Fuzzy Logic and Sliding-Mode Based Speed Control of Direct Torque and Flux Control Induction Motor Drives - A Comparative Study

    Science.gov (United States)

    Ramesh, Tejavathu; Panda, A. K.; Kumar, S. Shiva

    2013-08-01

    In this research study, the performance of direct torque and flux control induction motor drive (IMD) is presented using five different speed control techniques. The performance of IMD mainly depends on the design of speed controller. The PI speed controller requires precise mathematical model, continuous and appropriate gain values. Therefore, adaptive control based speed controller is desirable to achieve high-performance drive. The sliding-mode speed controller (SMSC) is developed to achieve continuous control of motor speed and torque. Furthermore, the type-1 fuzzy logic speed controller (T1FLSC), type-1 fuzzy SMSC and a new type-2 fuzzy logic speed controller are designed to obtain high performance, dynamic tracking behaviour, speed accuracy and also robustness to parameter variations. The performance of each control technique has been tested for its robustness to parameter uncertainties and load disturbances. The detailed comparison of different control schemes are carried out in a MATALB/Simulink environment at different speed operating conditions, such as, forward and reversal motoring under no-load, load and sudden change in speed.

  2. Direct measurement of the plasma equilibrium response to poloidal field changes and H∞ controller tests in TCV

    International Nuclear Information System (INIS)

    The control of ITER provides several challenges which can be met using existing techniques for the design of modern controllers. The specific case of the control of the Poloidal Field (PF) system has solicited considerable interest. One feature of the design of such controllers is their dependence on a sufficiently accurate model of the full system under control. To this end, experiments have been performed on the TCV tokamak to validate one plasma equilibrium response model, the CREATE-L model. Using a new technique, the open loop response of TCV has been directly measured in the frequency domain. These experimental results compare well with the CREATE-L model. This model was subsequently used to design a PF system controller, using methods proposed during the ITER EDA and the first test on TCV has been successful. (author)

  3. High performance control of an synchronous engine without speed indicator by direct control of the torque: Kalman filtering: control of the inverter commutation frequency; Commande haute performance d'un moteur asynchrone sans capteur de vitesse par controle direct du couple: filtrage de Kalman etendu du vecteur d'etat: controle de la frequence de commutation de l'onduleur

    Energy Technology Data Exchange (ETDEWEB)

    El Hassan, Ismail

    1999-07-01

    This thesis describes the development of a direct control of the torque and flow without a speed indicator for an asynchronous motor. The power is supplied by a two level inverter. The lack of mechanical sensor leads to a non linear simulation. This study is applied to a prototype. The obtained results show good static and dynamic performance of the speed regulator and the control robustness for the whole speed range. (A.L.B.)

  4. Reconfigurable multivariable control law for commercial airplane using a direct digital output feedback design

    Science.gov (United States)

    Ostroff, A. J.; Hueschen, R. M.

    1984-01-01

    The ability of a pilot to reconfigure the control surfaces on an airplane after a failure, allowing the airplane to recover to a safe condition for landing, becomes more difficult with increasing airplane complexity. Techniques are needed to stabilize and control the airplane immediately after a failure, allowing the pilot time to make longer range decisions. This paper shows a design of a discrete multivariable control law using four controls for the longitudinal channel of a B-737. Single control element failures are allowed in three of the four controls. The four controls design and failure cases are analyzed by means of a digital airplane simulation, with regard to tracking capability and ability to overcome severe windshear and turbulence during the aproach and landing phase of flight.

  5. Adolescents' Internalizing and Aggressive Behaviors and Perceptions of Parents' Psychological Control: A Panel Study Examining Direction of Effects

    Science.gov (United States)

    Albrecht, Arne K.; Galambos, Nancy L.; Jansson, S. Mikael

    2007-01-01

    This panel study investigated the directionality of relations between adolescents' perceptions of their parents' psychological control and adolescents' self-reported internalizing and aggressive (physical and relational) behaviors. Data were collected from a random, community sample of 530 adolescents ages 12-19 years old at time 1, and again 2…

  6. Work Stress and Depression among Direct Support Professionals: The Role of Work Support and Locus of Control

    Science.gov (United States)

    Gray-Stanley, J. A.; Muramatsu, N.; Heller, T.; Hughes, S.; Johnson, T. P.; Ramirez-Valles, J.

    2010-01-01

    Background: Although work stress can impede the capacity of direct support professionals and contribute to mental health challenges, external (i.e. work social support) and internal resources (i.e. an internal locus of control) have been shown to help DSPs cope more actively. We examined how work stress was associated with depression, with a…

  7. Effectiveness of female controlled barrier methods in preventing sexually transmitted infections and HIV: current evidence and future research directions

    OpenAIRE

    Minnis, A; Padian, N

    2005-01-01

    Objectives: To evaluate evidence for the effectiveness of female controlled physical and chemical barrier methods in preventing STI/HIV transmission, to examine recent reviews on microbicide development, and to highlight promising research directions. To discuss challenges in conducting effectiveness research and in translating results to public health intervention.

  8. Simulasi Pengaturan Kecepatan Motor Induksi Tiga Phasa Dengan Direct Torque Control Dengan Menggunakan Matlab 7.0.1

    OpenAIRE

    Jeremia Purba

    2009-01-01

    Motor induksi banyak dipergunakan dalam industri saat ini karena dalam penggunaannya motor induksi dapat dioperasikan dengan kecepatan yang bervariasi. Pengaturan kecepatan putaran motor induksi dapat dilakukan dengan beberapa metode dan salah satu metode yang digunakan adalah dengan mengatur torsi secara langsung. Direct Torque Control (DTC) merupakan teknologi terbaru yang dapat mengatur fluks dan torsi motor induksi secara langsung dengan mengatur vektor tegangannya. P...

  9. Micropump Fuel Mix Control for Novel Miniature Direct Methanol Fuel Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Energies and Power Densities of Direct Methanol Fuel Cells (DMFCs) are limited by the size and weight associated with the liquid pump, which must circulate the...

  10. Revisiting Controlled Quantum Secure Direct Communication Using a Non-symmetric Quantum Channel with Quantum Superdense Coding

    International Nuclear Information System (INIS)

    Recently Xia and Song [Phys. Lett. A 364 (2007) 117] have proposed a controlled quantum secure direct communication (CQSDC) protocol. They claimed that in their protocol only with the help of the controller Charlie, the receiver Alice can successfully extract the secret message from the sender Bob. In this letter, first we will show that within their protocol the controller Charlie's role could have been excluded if it were not for their unreasonable design. We then revise the Xia-Song CQSDC protocol such that its original advantages are retained and the CQSDC can be really realized

  11. Predictive control of a direct series resonant converter with active output voltage compensation

    OpenAIRE

    Reyes-Moraga, Eduardo Felipe

    2015-01-01

    Modern high power supplies are based on resonant converters in order to use high frequency reactive elements (for reduced size) without sacrificing converter efficiency. In an effort to achieve compact high power supplies, direct power converter topologies have been considered, since these are mainly characterised by their high power density. A direct resonant converter topology combines matrix converters with conventional resonant converters. This work focused on achieving high quality i...

  12. Weed control by direct injection of plant protection products according to specific situations

    OpenAIRE

    Krebs, Mathias; Rautmann, Dirk; Nordmeyer, Henning

    2016-01-01

    Precision Farming in agriculture allows a site-specific management of the crop. The aim of plant protection is to apply plant protection products (PPP) according to the site specific requirements on the field. Within the context of a research program to promote innovation, a sprayer with direct injection of plant protection products was developed. The direct injection offers site specific spraying of different individual PPP in a single pass. The sprayer prototype is equipped with a special s...

  13. Development of coke oven combustion control technology (I): combustion characteristics of coke in the vertical direction

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Y.; Yamamoto, T.; Katayama, A.; Takase, S.; Okui, N.

    1983-01-01

    Measurements of the temperature distribution in a coking chamber and sampling plus analysis of the product coke have confirmed that temperature fluctuations in the upper coking chamber of a single-stage burner type oven (such as a Koppers oven) have a large effect on the variations of coke quality. Control of such temperature fluctuations is therefore essential. A possible computerized combustion control system for improving temperature control is described. 2 references.

  14. Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems

    DEFF Research Database (Denmark)

    Preindl, Matthias; Schaltz, Erik

    2011-01-01

    The widely used cascade speed and torque controllers have a limited control performance in most high power applications due to the low switching frequency of power electronic converters and the convenience to avoid speed overshoots and oscillations for lifetime considerations. Model Predictive...... further improve dynamic behavior. It compensates the load torque influence on the speed control setting a feed forward torque reference value. The benefits are twice; the speed controller reaches the speed reference value without offsets which would need to be compensated by an integrator and a better...

  15. Development of valence-directed nanoparticle building blocks on the basis of controlled bio/nano-interfacing chemistry

    Science.gov (United States)

    Kim, Jeong-Hwan

    The assembly of nanoparticles in controllable and predictable ways would not only aid practical nanoscale assembly, which requires accurate and scalable assembly of large and complex nanoscale structures, but also would increase their utility for many applications, including electronics, optics, sensing and imaging, medical diagnostics, etc. Well-defined and controlled functionality and directionality of the building blocks are essential to actively control the molecular assembly processes at the nanometer scale. Such controls over the functionality and directionality would enable us to construct sophisticated nanostructures to take advantage of the increasing number of available nanocomponents and ultimately to approximate the complexity and the functionality of current microfabrication. We have developed a serial solid-phase placement approach to synthesize anisotropically or symmetrically functionalized gold nanoparticles (AuNPs), in which the functionality and directionality (e.g., numbers, locations, and orientations) of the functional ligands are controlled. Two types of bi-functionalized (bif-) AuNPs were synthesized at a site-specific manner with increased yield and accuracy: (1) homo-bif-AuNPs with two carboxyl groups at ˜180° angle (para-configuration) and (2) hetero-bif-AuNPs with one carboxyl and one amine functional groups at less than 180°, but greater than 90° angle (meta-configuration). With such control, we successfully demonstrated the assembly of intentionally designed one-dimensional (1D) chains with homo-bif-AuNPs and two-dimensional (2D) rings with hetero-bif-AuNPs, confirming the high functional as well as directional selectivity of the functionalized NPs. This study represents an important step towards accurate, reliable, and scaled-up manufacturing of complex nanoscale structures, potentially making 'bottom-up' nanofabrication of practical use. We have further developed the ligand replacement technology to achieve such active controls

  16. Multiple target implementation for a doubly fed induction generator based on direct power control under unbalanced and distorted grid voltage

    Institute of Scientific and Technical Information of China (English)

    Heng NIAN; Yi-peng SONG

    2015-01-01

    This paper presents a multiple target implementation technique for a doubly fed induction generator (DFIG) under unbalanced and distorted grid voltage based on direct power control (DPC). Based on the mathematical model of DFIG under unbalanced and distorted voltage, the proportional and integral (PI) regulator is adopted to regulate the DFIG average active and reactive powers, while the vector PI (VPI) resonant regulator is used to achieve three alternative control targets: (1) balanced and sinusoidal stator current; (2) smooth instantaneous stator active and reactive powers; (3) smooth electromagnetic torque and instantaneous stator reactive power. The major advantage of the proposed control strategy over the conventional method is that neither negative and harmonic sequence decomposition of grid voltage nor complicated control reference calculation is required. The insensitivity of the proposed control strategy to DFIG parameter deviation is analyzed. Finally, the DFIG experimental system is developed to validate the availability of the proposed DPC strategy under unbalanced and distorted grid voltage.

  17. Model Predictive Control for Integration of Industrial Consumers to the Smart Grid under a Direct Control Policy

    DEFF Research Database (Denmark)

    Rahnama, Samira; Stoustrup, Jakob; Rasmussen, Henrik

    2013-01-01

    In this paper, we propose a three-level hierarchical control framework for integration of industrial consumers to the future smart grid. With this structure, a balance responsible party (BRP) at the top level will be able to provide regulating power from the consumer side to help the power grid...

  18. Compensation of negative sequence stator flux of doubly-fed induction generator using polar voltage control-based direct torque control under unbalanced grid voltage condition

    Directory of Open Access Journals (Sweden)

    Badrinarayan Bansilal Pimple

    2015-02-01

    Full Text Available This study proposes a polar voltage control-based direct torque control method to reduce the effects of unbalanced grid voltage on doubly-fed induction generator (DFIG-based wind turbine system. Under unbalanced grid voltage, the stator flux has a negative sequence component which leads to second harmonic pulsation in torque, stator active power, stator reactive power, stator current and rotor current. In the control scheme, the negative sequence rotor voltage vector is controlled to compensate the negative sequence stator flux by negative sequence rotor flux. Simulation study is carried out on a 2 MW DFIG system using MATLAB/SIMULINK. Feasibility of the proposed control strategy is experimentally verified on a 1.5 kW DFIG system.

  19. DC-bus voltage control of grid-connected voltage source converter by using space vector modulated direct power control under unbalanced network conditions

    DEFF Research Database (Denmark)

    Xiao, Lei; Huang, Shoudao; Lu, Kaiyuan

    2013-01-01

    Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this...... study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component...... is introduced in the controller, which is necessary in order to reduce the dc-bus voltage ripple and active power harmonics at the same time. The proposed control topology is implemented in the lab. Simulation and experimental results are provided to validate its performance and the analysis...

  20. Global warming and house fly control: direct effects and biodiversity concerns.

    Science.gov (United States)

    House flies are major pests of human and animal health throughout the world and are among the most difficult to control. Effective fly management relies on a balance of sanitation, insecticide use, and biological control. Climate change could upset that balance in favor of the fly unless pro-activ...

  1. Onion weed control with post-directed applications of pelargonic acid

    Science.gov (United States)

    Organic onion producers need appropriate herbicides that can effectively provide post-emergent weed control. Research was conducted in southeast Oklahoma (Atoka County, Lane, OK) to determine the impact of a potential organic herbicide on weed control efficacy, crop injury, and yields. The experim...

  2. Access Control Mechanisms for Semantic Web services-A Discussion on Requirements & Future Directions

    CERN Document Server

    Gondara, Mandeep Kaur

    2011-01-01

    Semantic Web is an open, distributed, and dynamic environment where access to resources cannot be controlled in a safe manner unless the access decision takes into account during discovery of web services. Security becomes the crucial factor for the adoption of the semantic based web services. An access control means that the users must fulfill certain conditions in order to gain access over web services. Access control is important in both perspectives i.e. legal and security point of view. This paper discusses important requirements for effective access control in semantic web services which have been extracted from the literature surveyed. I have also discussed open research issues in this context, focusing on access control policies and models in this paper.

  3. Vibration control of the axisymmetric spherical pendulum by dynamic vibration absorber moving in radial direction

    International Nuclear Information System (INIS)

    In the current paper, a dynamic vibration absorber (DVA) is proposed to suppress the vibration of the axisymmetric spherical pendulum. The proposed DVA can reduce the bi-directional vibration of the pendulum by one mass, which moves in the radial direction (up and down). The global stability of the system is analyzed using the Lyapunov function. The proposed DVA is proven effective, especially for the suppression of large vibration. The DVA natural frequency should be tuned to twice as that of the axisymmetric spherical pendulum. The effectiveness of the proposed DVA is demonstrated through an example of liquid sloshing reduction in a cylindrical tank

  4. A new instantaneous torque control of PM synchronous motor for high-performance direct-drive applications

    Energy Technology Data Exchange (ETDEWEB)

    Chung, S.K. [Gyeongsang National Univ. (Korea, Republic of). Dept. of Control and Instrumentation Engineering; Kim, H.S.; Kim, C.G.; Youn, M.J. [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Electrical Engineering

    1998-05-01

    a new instantaneous torque-control strategy is presented for high-performance control of a permanent magnet (PM) synchronous motor. In order to deal with the torque pulsating problem of a PM synchronous motor in a low-speed region, new torque estimation and control techniques are proposed. The linkage flux of a PM synchronous motor is estimated using a model reference adaptive system technique, and the developed torque is instantaneously controlled by the proposed torque controller combining a variable structure control (VSC) with a space-vector pulse-width modulation (PWM). The proposed control provides the advantage of reducing the torque pulsation caused by the nonsinusoidal flux distribution. This control strategy is applied to the high-torque PM synchronous motor drive system for direct-drive applications and implemented by using a software of the digital signal processor (DSP) TMS320C30. The simulations and experiments are carried out for this system, and the results well demonstrate the effectiveness of the proposed control.

  5. Energy-Regenerative Braking Control of Electric Vehicles Using Three-Phase Brushless Direct-Current Motors

    Directory of Open Access Journals (Sweden)

    Bo Long

    2013-12-01

    Full Text Available Regenerative braking provides an effective way of extending the driving range of battery powered electric vehicles (EVs. This paper analyzes the equivalent power circuit and operation principles of an EV using regenerative braking control technology. During the braking period, the switching sequence of the power converter is controlled to inverse the output torque of the three-phase brushless direct-current (DC motor, so that the braking energy can be returned to the battery. Compared with the presented methods, this technology can achieve several goals: energy recovery, electric braking, ultra-quiet braking and extending the driving range. Merits and drawbacks of different braking control strategy are further elaborated. State-space model of the EVs under energy-regenerative braking operation is established, considering that parameter variations are unavoidable due to temperature change, measured error, un-modeled dynamics, external disturbance and time-varying system parameters, a sliding mode robust controller (SMRC is designed and implemented. Phase current and DC-link voltage are selected as the state variables, respectively. The corresponding control law is also provided. The proposed control scheme is compared with a conventional proportional-integral (PI controller. A laboratory EV for experiment is setup to verify the proposed scheme. Experimental results show that the drive range of EVs can be improved about 17% using the proposed controller with energy-regeneration control.

  6. The Effect of Faster Engine Response on the Lateral Directional Control of a Damaged Aircraft

    Science.gov (United States)

    May, Ryan D.; Lemon, Kimberly A.; Csank, Jeffrey T.; Litt, Jonathan S.; Guo, Ten-Huei

    2012-01-01

    The integration of flight control and propulsion control has been a much discussed topic, especially for emergencies where the engines may be able to help stabilize and safely land a damaged aircraft. Previous research has shown that for the engines to be effective as flight control actuators, the response time to throttle commands must be improved. Other work has developed control modes that accept a higher risk of engine failure in exchange for improved engine response during an emergency. In this effort, a nonlinear engine model (the Commercial Modular Aero-Propulsion System Simulation 40k) has been integrated with a nonlinear airframe model (the Generic Transport Model) in order to evaluate the use of enhanced-response engines as alternative yaw rate control effectors. Tests of disturbance rejection and command tracking were used to determine the impact of the engines on the aircraft's dynamical behavior. Three engine control enhancements that improve the response time of the engine were implemented and tested in the integrated simulation. The enhancements were shown to increase the engine s effectiveness as a yaw rate control effector when used in an automatic feedback loop. The improvement is highly dependent upon flight condition; the airframe behavior is markedly improved at low altitude, low speed conditions, and relatively unchanged at high altitude, high speed.

  7. Between the death penalty and decriminalization : new directions for drug control in the Commonwealth Caribbean

    Directory of Open Access Journals (Sweden)

    Axel Klein

    2001-07-01

    Full Text Available Traces the changes in public attitudes toward and political stances on drug control in the British Caribbean between 1980 and 2000. Author first discusses the origins of drug control, the role of US pressure, and the vulnerability of the Caribbean. He then looks at European involvement and the different plans and policies to control drugs in the region. Finally, he describes the consequences of these policy approaches on the justice system and legal reform, drug demand, and social structures in the region.

  8. Light sensitive memristor with bi-directional and wavelength-dependent conductance control

    Science.gov (United States)

    Maier, P.; Hartmann, F.; Rebello Sousa Dias, M.; Emmerling, M.; Schneider, C.; Castelano, L. K.; Kamp, M.; Marques, G. E.; Lopez-Richard, V.; Worschech, L.; Höfling, S.

    2016-07-01

    We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

  9. Ancillary Frequency Control of Direct Drive Full-Scale Converter Based Wind Power Plants

    OpenAIRE

    Hu, Weihao; Su, Chi; Fang, Jiakun; Chen, Zhe; Hu, Yanting

    2013-01-01

    This paper presents a simulation model of a wind power plant based on a MW-level variable speed wind turbine with a full-scale back-to-back power converter developed in the simulation tool of DIgSILENT Power Factory. Three different kinds of ancillary frequency control strategies, namely inertia emulation, primary frequency control and secondary frequency control, are proposed in order to improve the frequency stability of power systems. The modified IEEE 39-bus test system with a large-scale...

  10. Control of Inhibition by the Direct Action of Cannabinoids on GABAA Receptors

    NARCIS (Netherlands)

    Golovko, Tatiana; Min, R.; Lozovaya, Natalia; Falconer, Caroline; Yatsenko, Natalia; Tsintsadze, Timur; Tsintsadze, Vera; Ledent, Catherine; Harvey, Robert J; Belelli, Delia; Lambert, Jeremy J; Rozov, Andrei; Burnashev, Nail

    2015-01-01

    Cannabinoids are known to regulate inhibitory synaptic transmission via activation of presynaptic G protein-coupled cannabinoid CB1 receptors (CB1Rs). Additionally, recent studies suggest that cannabinoids can also directly interact with recombinant GABAA receptors (GABAARs), potentiating currents a

  11. Direct current generators with an optimal control; Generateur de tension continue a commande optimale

    Energy Technology Data Exchange (ETDEWEB)

    Laeuffer, J.; Nuns, T.; Planas, T.; Fadel, M.; Piquet, H.

    1995-05-05

    This patent deals with direct current generators using a resonant rectifier working in a continuous or discontinuous rating according to an hypo-resonant mode with a high voltage establishment as shorter as possible for medical applications. (A.B.). 4 refs., 14 figs.

  12. Forum: Interaction of State Aid, Free Movement, Policy Competition and Abuse Control in Direct Tax Matters

    NARCIS (Netherlands)

    P.J. Wattel

    2013-01-01

    The European Union has woken up to State aid possibly contained in national direct tax measures. As a result, the number of Commission actions against Member States on the basis of fiscal State aid has increased in recent years, with some amazing results. It has also revealed overlap and concurrence

  13. Control of crystal growth in water purification by directional freeze crystallization

    Science.gov (United States)

    Conlon, William M. (Inventor)

    1996-01-01

    A Directional Freeze Crystallization system employs an indirect contact heat exchanger to freeze a fraction of liquid to be purified. The unfrozen fraction is drained away and the purified frozen fraction is melted. The heat exchanger must be designed in accordance with a Growth Habit Index to achieve efficient separation of contaminants. If gases are dissolved in the liquid, the system must be pressurized.

  14. IM Direct Torque Control with no flux distortion and no static torque error.

    Science.gov (United States)

    Lokriti, Abdesslam; Salhi, Issam; Doubabi, Said

    2015-11-01

    The purpose of this paper is to improve DTC control strategy performances. In fact, we propose controlling both stator flux components (real and imaginary) through two hysteresis controllers. Thus, a new switching table which is independent from sector determination, and does not introduce zero voltage vectors is established; with much reduced size when compared to Takahashi's one. The proposed strategy has allowed cutting off with flux and current harmonics related to distortion caused by sector exchanges. Also, we provide theoretical evidence about the existence of static torque error in classical DTC, and propose a simple PI-type controller to cancel it. The proposed strategy is validated by simulation and practically on a DSPace 1104 board, for a 1.5 (kW) induction motor and various torque references. PMID:26391487

  15. Enhancement in Steady State and Dynamic Performance of Direct Torque Control Induction Motor Drive

    Science.gov (United States)

    Singh, Bhoopendra; Jain, Shailendra; Dwivedi, Sanjeet

    2013-09-01

    An enhancement in dynamic performance of a traditional DTC drive can be achieved by a robust speed control algorithm while the steady state performance depends upon the switching strategy selected for minimization of torque ripples and an efficient flux control loop. In this paper a new torque ripple reduction technique with a modified look up table incorporating a larger number of synthesized non zero active voltage vectors is utilized to overcome the limitations of the conventionally controlled DTC drive. A fuzzy logic based speed controller and a low pass filter with tunable cutoff frequency for flux estimation is proposed in this paper. The proposed study is investigated through simulation and experimentally validated on a test drive.

  16. Direct Method for Resolution of Optimal Control Problem with Free Initial Condition

    Directory of Open Access Journals (Sweden)

    Louadj Kahina

    2012-01-01

    Full Text Available The theory of control analyzes the proprieties of commanded systems. Problems of optimal control (OC have been intensively investigated in the world literature for over forty years. During this period, series of fundamental results have been obtained, among which should be noted the maximum principle (Pontryagin et al., 1962 and dynamic programming (Bellman, 1963. For many of the problems of the optimal control theory (OCT, adequate solutions are found (Bryson and Yu-chi, 1969, Lee and Markus, 1967, Gabasov and Kirillova, 1977, 1978, 1980. Results of the theory were taken up in various fields of science, engineering, and economics. The present paper aims at extending the constructive methods of Balashevich et al., (2000 that were developed for the problems of optimal control with the bounded initial state is not fixed are considered.

  17. New Directions for Understanding Neural Control in Swallowing: The Potential and Promise of Motor Learning

    OpenAIRE

    Humbert, Ianessa A.; German, Rebecca Z.

    2012-01-01

    Oropharyngeal swallowing is a complex sensorimotor phenomenon that has had decades of research dedicated to understanding it more thoroughly. However, the underlying neural mechanisms responsible for normal and disordered swallowing remain very vague. We consider this gap in knowledge the result of swallowing research that has been broad (identifying phenomena) but not deep (identifying what controls the phenomena). The goals of this review are to address the complexity of motor control of or...

  18. PERFORMANCE ENHANCEMENT OF DIRECT TORQUE CONTROL OF INDUCTION MOTOR USING FUZZY LOGIC

    OpenAIRE

    P. Sweety Jose; Jovitha Jerome; S. Sathya Bama

    2011-01-01

    DTC is strategy of selecting proper stator voltage vectors to reduce torque error and flux error. DTC uses hysteresis band controller whose control action has no difference between large torque error and small one. This results in high torque ripple. In order to reduce the torque ripple and to improve the performance of DTC, DTC based on Fuzzy Logic is proposed in this paper. The simulations are carried out using MATLAB and comparison is made between conventional DTC and DTC using Fuzzy Logic...

  19. Direct field oriented control of induction motor fed by wind turbine generator under saturation effect

    OpenAIRE

    Guettaf, Abderazak; Bettka, Ahmed; Bennis, Ouafae; Benchabane, Fateh; Khaled, Yahia; Ali, Arif

    2011-01-01

    In this paper, we present the voltage build up process and the terminal voltage control of an isolated wind powered induction generator driven by a variable speed wind turbine using rotor flux oriented vector control. A description of the studied system is provided, and a simulation study is presented. The model used for the autonomous induction generator is a diphase one obtained by application of the Park transform. Theis model permits, when adopting some simplifying hypotheses, taking acco...

  20. Designing a sensorless torque estimator for direct torque control of an induction motor

    OpenAIRE

    Tsoutsas, Athanasios

    2009-01-01

    Nowadays, transportation is a major cause of air pollution. Electric propulsion could replace the internal combustion engines of automobiles and reduce the emission of exhaust gases. The propulsion of an electric vehicle requires the design of an accurate electromagnetic torque estimator and an efficient control system in order to control the speed of the vehicle. This concept is conveyed through this thesis. An electromagnetic torque calculator of an induction motor is designed in the Simuli...

  1. Intelligent Microstepping System for Bipolar Stepper Motor Control with Step and Direction Interface

    OpenAIRE

    Alexandru Morar; Lucian Dăscălescu

    2010-01-01

    The paper presents a intelligent system for stepper motor control in a microstepping mode, which was designed and performed with a specialized integrated circuit (L292), made by SGS-THOMSON Microelectronics Company. With an interface and an adequate software, L292 circuit can be used as a chopper in 2 or 4 quadrant. The microstepping control system improves the positioning accuracy and eliminates low speed ripple and resonance effects in a stepper motor electric drive. The same microstepping ...

  2. A Osteogenesis Distraction Device Enabling Control of Vertical Direction for Syndromic Craniosynostosis

    OpenAIRE

    Shinji Kobayashi, MD; Toshihiko Fukawa, DDS; Takashi Hirakawa, DDS; Jiro Maegawa, MD

    2014-01-01

    Background: We have developed a hybrid facial osteogenesis distraction system that combines the advantages of external and internal distraction devices to enable control of both the distraction distance and vector. However, when the advanced maxilla has excessive clockwise rotation and shifts more downward vertically than planned, it might be impossible to pull it up to correct it. We invented devices attached to external distraction systems that can control the vertical vector of distraction...

  3. Evidence that RpoS (sigmaS) in Borrelia burgdorferi is controlled directly by RpoN (sigma54/sigmaN).

    Science.gov (United States)

    Smith, Alexandra H; Blevins, Jon S; Bachlani, Gulnaz N; Yang, Xiaofeng F; Norgard, Michael V

    2007-03-01

    The alternative sigma factor (RpoN-RpoS) pathway controls the expression of key virulence factors in Borrelia burgdorferi. However, evidence to support whether RpoN controls rpoS directly or, perhaps, indirectly via a transactivator has been lacking. Herein we provide biochemical and genetic evidence that RpoN directly controls rpoS in B. burgdorferi. PMID:17158681

  4. Predictive direct power control for photovoltaic grid connected system: An approach based on multilevel converters

    International Nuclear Information System (INIS)

    Highlights: • The paper presents a new control method of a photovoltaic grid connected system. • The control strategy is simple, no need for regulators or modulation techniques. • The control method uses a cost function to be minimized for each voltage vector. • Once the strategy is approved, a multilevel inverter is used to improve the results. - Abstract: The paper presents an improved predictive power control for a photovoltaic conversion chain connected to a grid based on finite states space model of the converter. The proposed control algorithm selects the switching state of the inverter that minimizes the error between active and reactive power predictions to their computed values for all different voltage vectors. The optimal voltage vector that minimizes a cost function is then applied to the output of the power converter. Once the proposed predictive strategy is validated, a multilevel converter is then used to improve and highlight the obtained results. The proposed predictive control strategy uses only one sample time prediction and it is very intuitive since it is very simple and provides best performances compared to other modulation techniques

  5. Co op erative Iterative Learning Control of Linear Multi-agent Systems with a Dynamic Leader under Directed Top ologies

    Institute of Scientific and Technical Information of China (English)

    PENG Zhou-Hua; WANG Dan; WANG Hao; WANG Wei

    2014-01-01

    This paper considers the cooperative tracking of linear multi-agent systems with a dynamic leader whose input informa-tion is unavailable to any followers. Cooperative iterative learning controllers, based on the relative state information of neighboring agents, are proposed for tracking the dynamic leader over directed communication topologies. Stability and convergence of the proposed controllers are established using Lyapunov-Krasovskii functionals. Furthermore, this result is extended to the output feedback case where only the output information of each agent can be obtained. A local observer is constructed to estimate the unmeasurable states. Then, cooperative iterative learning controllers, based on the relative observed states of neighboring agents, are devised. For both cases, it is shown that the multi-agent systems whose communication topologies contain a spanning tree can reach synchronization with the dynamic leader, and meanwhile identify the unknown input of the dynamic leader using distributed iterative learning laws. An illustrative example is provided to verify the proposed control schemes.

  6. Optically and thermally controlled terahertz metamaterial via transition between direct and indirect electromagnetically induced transparency

    Directory of Open Access Journals (Sweden)

    Jiawei Sui

    2014-12-01

    Full Text Available This passage presents a design of tunable terahertz metamaterials via transition between indirect and direct electromagnetically induced transparency (EIT effects by changing semiconductor InSb’s properties to terahertz wave under optical and thermal stimuli. Mechanical model and its electrical circuit model are utilized in analytically calculating maximum transmission of transparency window. Simulated results show consistency with the analytical expressions. The results show that the metamaterials hold 98.4% modulation depth at 189 GHz between 300 K, σInSb =256000 S/m, and 80 K, σInSb =0.0162 S/m conditions , 1360 ps recovery time of the excited electrons in InSb under optical stimulus at 300 K mainly considering the direct EIT effect, and minimum bandwidth 1 GHz.

  7. Modulation of Pain with Transcranial Direct Current Stimulation and Diffuse Noxious Inhibitory Controls

    OpenAIRE

    Reidler, Jay S.

    2014-01-01

    Background: While pain is essential for physiological functioning, chronic or pathologic pain is responsible for a major burden of disease in society. Novel approaches to treating acute and chronic pain have employed neuromodulatory tools to target the central and peripheral neural structures that mediate pain. Transcranial direct current stimulation (tDCS), for example, is a safe, non-invasive brain stimulation technique that has been shown in preliminary studies to reduce chronic pain when ...

  8. Early Stage of Walking: Development of Control in Mediolateral and Anteroposterior Directions

    OpenAIRE

    Kubo, Masayoshi; Ulrich, Beverly D.

    2006-01-01

    The authors examined the changes in bipedal gait of toddlers in the anteroposterior (AP) and mediolateral (ML) directions, as a set, at the onset of independent gait and 1 month after onset. Two groups with distinctly different dynamic resources were studied: 8 toddlers with typical development (TD) and 8 toddlers with Down syndrome (DS). Three-dimensional kinematic data were collected, and gait parameters, such as walking speed, stride length, and stride frequency, as well as the ratio of ex...

  9. Directed transport in coupled noisy Josephson junctions controlled via ac signals

    OpenAIRE

    Machura, L.; Spiechowicz, J.; Luczka, J.

    2012-01-01

    Transport properties of two coupled Josephson junctions driven by ac currents and thermal fluctuations are studied with the purpose of determining dc voltage characteristics. It is a physical realization of directed transport induced by a non-biased zero averaged external signal. The ac current is applied either to (A) only one junction as a biharmonic current or (B) is split into two simple harmonic components and separately applied to respective junctions. We identify regimes where junction...

  10. Controllable directive radiation of a magnetic dipole above planar metal surface

    OpenAIRE

    Xi, Zheng; Lu, Yonghua; Yao, Peijun; Yu, Wenhai; Wang, Pei; Ming, Hai

    2013-01-01

    We report unidirectional radiation of a magnetic dipole above planar metal surface, the radiation direction can be manipulated via changing the distance between the dipole and the surface. This phenomenon is unique for the combination of magnetic dipole and metal surface and does not happen for linear polarized dipole on metal surface or magnetic dipole on dielectric surface. The underlining physics is analytically disclosed by the interference of two orthogonally-oriented dipole component wi...

  11. Brushless Direct Current Motor Control Using Sensorless Single-signal Feedback

    OpenAIRE

    2006-01-01

    This report is a study into the use of a novel Compound back Electromotive Force (CBEMF) method for driving brushless direct current (BLDC) motors. The study was conducted in an attempt to find a simpler drive-method that would allow fast motor rotation with less powerful microcontrollers. The results show this method to be viable, and that further study may be beneficial. CBEMF signal is a composite signal containing feedback information from all 3 motor phases. By utilizing the CBEMF p...

  12. Increasing Fuel Efficiency of Direct Methanol Fuel Cell Systems with Feedforward Control of the Operating Concentration

    OpenAIRE

    Youngseung Na; Federico Zenith; Ulrike Krewer

    2015-01-01

    Most of the R&D on fuel cells for portable applications concentrates on increasing efficiencies and energy densities to compete with other energy storage devices, especially batteries. To improve the efficiency of direct methanol fuel cell (DMFC) systems, several modifications to system layouts and operating strategies are considered in this paper, rather than modifications to the fuel cell itself. Two modified DMFC systems are presented, one with an additional inline mixer and a further ...

  13. Direct control of the small-scale energy balance in 2D fluid dynamics

    OpenAIRE

    Frank, Jason; Leimkuhler, Ben; Myerscough, Keith

    2015-01-01

    We explore the direct modification of the pseudo-spectral truncation of 2D, incompressible fluid dynamics to maintain a prescribed kinetic energy spectrum. The method provides a means of simulating fluid states with defined spectral properties, for the purpose of matching simulation statistics to given information, arising from observations, theoretical prediction or high fidelity simulation. In the scheme outlined here, Nos\\'{e}-Hoover thermostats, commonly used in molecular dynamics, are in...

  14. Development of swashplateless helicopter blade pitch control system using the limited angle direct-drive motor (LADDM

    Directory of Open Access Journals (Sweden)

    Wang Jian

    2015-10-01

    Full Text Available It can be greatly beneficial to remove the swashplate of conventional helicopter, because the swashplate is usually complicated, aerodynamically resistive, and obstacle of more complex pitch control for improving performance. The present technologies for helicopter vibration reduction are usually narrow in effective range or requiring additional actuators and signal transfer links, and more effective technology is desired. Helicopter blade pitch control system, which is removed of swashplate and integrated high-frequency pitch control function for active vibration reduction, is likely the suitable solution at current technical level. Several potential implementation schemes are discussed, such as blades being directly or indirectly driven by actuators mounted in rotating frame and application of different types of actuators, especially implementation schemes of electro-mechanical actuator with or without gear reducer. It is found that swashplateless blade pitch control system based on specially designed limited angle direct-drive motor (LADDM is a more practical implementation scheme. An experimental prototype of the finally selected implementation scheme has been designed, fabricated and tested on rotor tower. The test results show considerable feasibility of the swashplateless helicopter blade pitch control system using the LADDM.

  15. Sensorless Direct Field-Oriented Control of Three-Phase Induction Motor Drives for Low-Cost Applications

    OpenAIRE

    Bojoi, Iustin Radu; Guglielmi, Paolo; Pellegrino, Gian-Mario Luigi

    2008-01-01

    A sensorless direct rotor field-oriented control (SDRFOC) scheme of three-phase induction motors for low-cost applications is presented in this paper. The SDRFOC algorithm is based on a sensorless closed-loop rotor flux observer whose main advantages are simplicity and robustness to motor parameter detuning. The whole algorithm has been developed and implemented on a low-cost fixed-point digital signal processor controller. Experimental results are presented for a 0.5-kW induction motor drive...

  16. [Comparison between the official indirect method and the direct method of control of vaccines against sheep enterotoxemia].

    Science.gov (United States)

    Dufrene, M; Poul, J; Gayot, G

    1976-01-01

    The official methods of control of vaccines against sheep enterotoxemia are indirect in two ways : on the one hand they are carried out on animals for which the vaccine is not intended, and on the other hand they test only an immunological serum reaction. Another method consisting of direct testing by intravenous injection of toxin has been carried out on mice previously vaccinated with different doses. It has been shown that it is possible to obtain a certain level of protection giving a good dose-effect relation. However, immunity provided by this direct method is weak although the vaccine utilized is considered very efficacious with regard to the official norms of the direct test. These results, which are both encouraging and disappointing, will be the subject of a more intensive study of the different parameters in question. PMID:187512

  17. Improvements to the TRIGA Mark II instrumentation and the direct digital control by microprocessors

    International Nuclear Information System (INIS)

    Two tendencies have been present in the maintenance of the TRIGA instrumentation: one was to renew only those parts that were deteriorating with age, thus ensuring the continuation of the satisfactory service in the original scope; the other was aimed at adding new features and possibly at changing the whole concept of the reactor control and instrumentation. Though the activities along both lines were not best coordinated at all times, the presently emerging result may be highly satisfactory. Besides the well maintained instrumentation in the original scope and concept, a digital data logging and control system is being installed, based on microprocessors, which should offer new level of flexibility and convenience to the operators and experimenters, without compromising either safety of reliability of the overall instrumentation and control system

  18. Intelligent Microstepping System for Bipolar Stepper Motor Control with Step and Direction Interface

    Directory of Open Access Journals (Sweden)

    Alexandru Morar

    2010-06-01

    Full Text Available The paper presents a intelligent system for stepper motor control in a microstepping mode, which was designed and performed with a specialized integrated circuit (L292, made by SGS-THOMSON Microelectronics Company. With an interface and an adequate software, L292 circuit can be used as a chopper in 2 or 4 quadrant. The microstepping control system improves the positioning accuracy and eliminates low speed ripple and resonance effects in a stepper motor electric drive. The same microstepping system is ideal for robotics, printers, plotters, X-Y-Z tables and can facilitate the construction of very sophisticated positioning control systems while significantly reducing component cost, board space, design time and systems cost.

  19. Control of Formation-Flying Multi-Element Space Interferometers with Direct Interferometer-Output Feedback

    Science.gov (United States)

    Lu, Hui-Ling; Cheng, H. L.; Lyon, Richard G.; Carpenter, Kenneth G.

    2007-01-01

    The long-baseline space interferometer concept involving formation flying of multiple spacecraft holds great promise as future space missions for high-resolution imagery. A major challenge of obtaining high-quality interferometric synthesized images from long-baseline space interferometers is to accurately control these spacecraft and their optics payloads in the specified configuration. Our research focuses on the determination of the optical errors to achieve fine control of long-baseline space interferometers without resorting to additional sensing equipment. We present a suite of estimation tools that can effectively extract from the raw interferometric image relative x/y, piston translational and tip/tilt deviations at the exit pupil aperture. The use of these error estimates in achieving control of the interferometer elements is demonstrated using simulated as well as laboratory-collected interferometric stellar images.

  20. Controlled quantum secure direct communication by entanglement distillation or generalized measurement

    Science.gov (United States)

    Tan, Xiaoqing; Zhang, Xiaoqian

    2016-05-01

    We propose two controlled quantum secure communication schemes by entanglement distillation or generalized measurement. The sender Alice, the receiver Bob and the controllers David and Cliff take part in the whole schemes. The supervisors David and Cliff can control the information transmitted from Alice to Bob by adjusting the local measurement angles θ _4 and θ _3. Bob can verify his secret information by classical one-way function after communication. The average amount of information is analyzed and compared for these two methods by MATLAB. The generalized measurement is a better scheme. Our schemes are secure against some well-known attacks because classical encryption and decoy states are used to ensure the security of the classical channel and the quantum channel.

  1. Global output regulation of a class of lower triangular nonlinear systems with unknown control direction via output feedback

    Science.gov (United States)

    Li, Ranran

    2016-05-01

    In this paper, we study the global output regulation problem of a class of lower triangular systems under measurement output feedback. A novel high-gain filter is proposed to estimate the unmeasured states of the systems. Furthermore, we integrate the robust stabilisation technique and Nussbaumgain technique to achieve asymptotic regulation when the control direction is unknown. The simulation results illustrate the effectiveness of the proposed method.

  2. Fault Characteristics and Control Strategies of Multiterminal High Voltage Direct Current Transmission Based on Modular Multilevel Converter

    OpenAIRE

    Fei Chang; Zhongping Yang; Yi Wang; Fei Lin; Shihui Liu

    2015-01-01

    The modular multilevel converter (MMC) is an emerging voltage source converter topology suitable for multiterminal high voltage direct current transmission based on modular multilevel converter (MMC-MTDC). This paper presents fault characteristics of MMC-MTDC including submodule fault, DC line fault, and fault ride-through of wind farm integration. Meanwhile, the corresponding protection strategies are proposed. The correctness and effectiveness of the control strategies are verified by estab...

  3. Rif1 controls DNA replication by directing Protein Phosphatase 1 to reverse Cdc7-mediated phosphorylation of the MCM complex

    OpenAIRE

    Hiraga, Shin-ichiro; Alvino, Gina M.; Chang, FuJung; Lian, Hui-Yong; Sridhar, Akila; Kubota, Takashi; Brewer, Bonita J.; Weinreich, Michael; Raghuraman, M. K.; Donaldson, Anne D.

    2014-01-01

    Recent evidence points to a role for Rif1 (Rap1-interacting factor) in DNA replication and genomic stability; however, the mechanism by which Rif1 functions has remained elusive. Hiraga el al. now report that budding yeast Rif1 controls DNA replication genome-wide and describe how Rif1 opposes Dbf4-dependent kinase (DDK) function by directing Protein Phosphatase 1 (PP1)-mediated dephosphorylation of the MCM complex. PP1 interaction sites are evolutionarily conserved within the Rif1 sequence; ...

  4. The microbiome quality control project: baseline study design and future directions.

    Science.gov (United States)

    Sinha, Rashmi; Abnet, Christian C; White, Owen; Knight, Rob; Huttenhower, Curtis

    2015-01-01

    Microbiome research has grown exponentially over the past several years, but studies have been difficult to reproduce across investigations. Relevant variation in measurements between laboratories, from a variety of sources, has not been systematically assessed. This is coupled with a growing concern in the scientific community about the lack of reproducibility in biomedical research. The Microbiome Quality Control project (MBQC) was initiated to identify sources of variation in microbiome studies, to quantify their magnitudes, and to assess the design and utility of different positive and negative control strategies. Here we report on the first MBQC baseline study project and workshop. PMID:26653756

  5. Controlled drilling technology for HLW management. Directional drilling and mechanics/stress measurements in the borehole

    International Nuclear Information System (INIS)

    Since 2000, Central Research Institute of Electric Power Industry (CRIEPI) has been conducting the project on controlled drilling and the logging/measurement technologies in its boreholes. Especially borehole pressure meter and bore hole stress measurement apparatus which can apply to the controlled drilling system was developed. The bore hole was drilled to the 1000 m long in order to intersect the Omagari fault located at Horonobe town in Hokkaido and its core recovery was 99.8% as of FY. 2011. Using borehole logging/measurement/survey, the geological, hydrological, geo-mechanical, geophysical and geochemical data were collected and the Omagari fault was characterized. (author)

  6. Immunity induced by a broad class of inorganic crystalline materials is directly controlled by their chemistry

    NARCIS (Netherlands)

    G.R. Williams (Gareth); K. Fierens (Kaat); S.G. Preston (Stephen); A.C. Lunn; O. Rysnik (Oliwia); S. de Prijck (Sofie); M. Kool (Mirjam); H.C. Buckley (Hannah); B.N.M. Lambrecht (Bart); D. O'Hare (Dermot); J.M. Austyn (Jonathan)

    2014-01-01

    textabstractThere is currently no paradigm in immunology that enables an accurate prediction of how the immune system will respond to any given agent. Here we show that the immunological responses induced by members of a broad class of inorganic crystalline materials are controlled purely by their p

  7. Direct Adaptive Control of a Class of Nonlinear Discrete-Time Systems

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon

    , which implies that the control law is completely discribed in terms of its parameter vector. Using Lyapunov-like analysis, we show that it is possible to stabilize the closed loop semi-globally in the presence of non-sectorbounded nonlinearities. The result relies on a nonlinear weighting of the...

  8. Influence of Parenting Factors on Childhood Social Anxiety: Direct Observation of Parental Warmth and Control

    Science.gov (United States)

    Rork, Kristine E.; Morris, Tracy L.

    2009-01-01

    The purpose of the present study is to determine the association of parenting behaviors and social anxiety in children. Three parental factors--including parental socialization, control, and warmth--were investigated in a sample of 31 two-parent families. Rather than solely relying upon retrospective questionnaires, this study incorporated direct…

  9. Making the Connections with Direct Experience: From the Western Front to User-Controlled Research

    Science.gov (United States)

    Beresford, Peter

    2006-01-01

    A new research approach, related to action research and new paradigm research, has been emerging in recent years. This is (service) user-controlled research. It challenges positivist values of "neutrality", "distance" and "objectivity" in research and explicitly values subjectivity and experiential knowledge. The author examines how his personal…

  10. Ancillary Frequency Control of Direct Drive Full-Scale Converter Based Wind Power Plants

    DEFF Research Database (Denmark)

    Hu, Weihao; Su, Chi; Fang, Jiakun; Chen, Zhe; Hu, Yanting

    2013-01-01

    This paper presents a simulation model of a wind power plant based on a MW-level variable speed wind turbine with a full-scale back-to-back power converter developed in the simulation tool of DIgSILENT Power Factory. Three different kinds of ancillary frequency control strategies, namely inertia...

  11. Sequestration of flue gas CO₂ by direct gas-solid carbonation of air pollution control system residues.

    Science.gov (United States)

    Tian, Sicong; Jiang, Jianguo

    2012-12-18

    Direct gas-solid carbonation reactions of residues from an air pollution control system (APCr) were conducted using different combinations of simulated flue gas to study the impact on CO₂ sequestration. X-ray diffraction analysis of APCr determined the existence of CaClOH, whose maximum theoretical CO₂ sequestration potential of 58.13 g CO₂/kg APCr was calculated by the reference intensity ratio method. The reaction mechanism obeyed a model of a fast kinetics-controlled process followed by a slow product layer diffusion-controlled process. Temperature is the key factor in direct gas-solid carbonation and had a notable influence on both the carbonation conversion and the CO₂ sequestration rate. The optimal CO₂ sequestrating temperature of 395 °C was easily obtained for APCr using a continuous heating experiment. CO₂ content in the flue gas had a definite influence on the CO₂ sequestration rate of the kinetics-controlled process, but almost no influence on the final carbonation conversion. Typical concentrations of SO₂ in the flue gas could not only accelerate the carbonation reaction rate of the product layer diffusion-controlled process, but also could improve the final carbonation conversion. Maximum carbonation conversions of between 68.6% and 77.1% were achieved in a typical flue gas. Features of rapid CO₂ sequestration rate, strong impurities resistance, and high capture conversion for direct gas-solid carbonation were proved in this study, which presents a theoretical foundation for the applied use of this encouraging technology on carbon capture and storage. PMID:23181908

  12. Controlled fabrication of nanopores using a direct focused ion beam approach with back face particle detection

    Science.gov (United States)

    Patterson, N.; Adams, D. P.; Hodges, V. C.; Vasile, M. J.; Michael, J. R.; Kotula, P. G.

    2008-06-01

    We report a direct, ion drilling technique that enables the reproducible fabrication and placement of nanopores in membranes of different thickness. Using a 30 keV focused Ga ion beam column combined with an in situ, back face, multi-channelplate particle detector, nanopores are sputtered in Si3N4 and W/Si3N4 to have diameters as small as 12 nm. Transmission electron microscopy shows that focused ion beam-drilled holes are near-conical with the diameter decreasing from entry to exit side. By monitoring the detector signal during ion exposure, the drilled hole width can be minimized such that the exit-side diameter is smaller than the full width at half-maximum of the nominally Gaussian-shaped incident beam. Judicious choice of the beam defining aperture combined with back face particle detection allows for reproducible exit-side hole diameters between 18 and 100 nm. The nanopore direct drilling technique does not require potentially damaging broad area exposure to tailor hole sizes. Moreover, this technique successfully achieves breakthrough despite the effects of varying membrane thickness, redeposition, polycrystalline grain structure, and slight ion beam current fluctuations.

  13. Controlled fabrication of nanopores using a direct focused ion beam approach with back face particle detection

    International Nuclear Information System (INIS)

    We report a direct, ion drilling technique that enables the reproducible fabrication and placement of nanopores in membranes of different thickness. Using a 30 keV focused Ga ion beam column combined with an in situ, back face, multi-channelplate particle detector, nanopores are sputtered in Si3N4 and W/Si3N4 to have diameters as small as 12 nm. Transmission electron microscopy shows that focused ion beam-drilled holes are near-conical with the diameter decreasing from entry to exit side. By monitoring the detector signal during ion exposure, the drilled hole width can be minimized such that the exit-side diameter is smaller than the full width at half-maximum of the nominally Gaussian-shaped incident beam. Judicious choice of the beam defining aperture combined with back face particle detection allows for reproducible exit-side hole diameters between 18 and 100 nm. The nanopore direct drilling technique does not require potentially damaging broad area exposure to tailor hole sizes. Moreover, this technique successfully achieves breakthrough despite the effects of varying membrane thickness, redeposition, polycrystalline grain structure, and slight ion beam current fluctuations

  14. Laser-directed hierarchical assembly of liquid crystal defects and control of optical phase singularities.

    Science.gov (United States)

    Ackerman, Paul J; Qi, Zhiyuan; Lin, Yiheng; Twombly, Christopher W; Laviada, Mauricio J; Lansac, Yves; Smalyukh, Ivan I

    2012-01-01

    Topological defect lines are ubiquitous and important in a wide variety of fascinating phenomena and theories in many fields ranging from materials science to early-universe cosmology, and to engineering of laser beams. However, they are typically hard to control in a reliable manner. Here we describe facile erasable "optical drawing" of self-assembled defect clusters in liquid crystals. These quadrupolar defect clusters, stabilized by the medium's chirality and the tendency to form twisted configurations, are shaped into arbitrary two-dimensional patterns, including reconfigurable phase gratings capable of generating and controlling optical phase singularities in laser beams. Our findings bridge the studies of defects in condensed matter physics and optics and may enable applications in data storage, singular optics, displays, electro-optic devices, diffraction gratings, as well as in both optically- and electrically-addressed pixel-free spatial light modulators. PMID:22679553

  15. Future directions in controlling the LAMPF-PSR accelerator complex at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Four interrelated projects are underway whose purpose is to migrate the LAMPF-PSR Accelerator Complex control systems to a system with a common set of hardware and software components. Project goals address problems in performance, maintenance and growth potential. Front-end hardware, operator interface hardware and software, computer systems, network systems and data system software are being simultaneously upgraded as part of these efforts. The efforts are being coordinated to provide for a smooth and timely migration to a client-server model-based data acquisition and control system. An increased use of distributed intelligence at both the front-end and the operator interface is a key element of the projects. (author)

  16. Future directions in controlling the LAMPF-PSR Accelerator Complex at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Four interrelated projects are underway whose purpose is to migrate the LAMPF-PSR Accelerator Complex control systems to a system with a common set of hardware and software components. Project goals address problems in performance, maintenance and growth potential. Front-end hardware, operator interface hardware and software, computer systems, network systems and data system software are being simultaneously upgraded as part of these efforts. The efforts are being coordinated to provide for a smooth and timely migration to a client-sever model-based data acquisition and control system. An increased use of the distributed intelligence at both the front-end and operator interface is a key element of the projects. 2 refs., 2 figs

  17. Modified Direct Torque Control of Three-Phase Induction Motor Drives with Low Ripple in Flux and Torque

    Directory of Open Access Journals (Sweden)

    Vinay KUMAR

    2011-06-01

    Full Text Available This paper proposes an algorithm for direct flux and torque controlled three phase induction motor drive systems. This method is based on control of slip speed and decoupled between amplitude and angle of reference stator flux for determining required stator voltage vector. In this proposes model, integrator unit is not required to generate the reference stator flux angle for calculating required stator voltage vector, hence it eliminates the initial values problems in real time. Within the given sampling time, flux as well as torque errors are controlled by stator voltage vector which is evaluated from reference stator flux. The direct torque control is achieved by reference stator flux angle which is generates from instantaneous slip speed angular frequency and stator flux angular frequency. The amplitude of the reference stator flux is kept constant at rated value. This technique gives better performance in three-phase induction motor than conventional technique. Simulation results for 3hp induction motor drive, for both proposed and conventional techniques, are presented and compared. From the results it is found that the stator current, flux linkage and torque ripples are decreased with proposed technique.

  18. Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control

    Science.gov (United States)

    McGovern, Scott; Alici, Gursel; Truong, Van-Tan; Spinks, Geoffrey

    2009-09-01

    This paper presents the development of an autonomously powered and controlled robotic fish that incorporates an active flexural joint tail fin, activated through conducting polymer actuators based on polypyrrole (PPy). The novel electromaterial muscle oscillator (NEMO) tail fin assembly on the fish could be controlled wirelessly in real time by varying the frequency and duty cycle of the voltage signal supplied to the PPy bending-type actuators. Directional control was achieved by altering the duty cycle of the voltage input to the NEMO tail fin, which shifted the axis of oscillation and enabled turning of the robotic fish. At low speeds, the robotic fish had a turning circle as small as 15 cm (or 1.1 body lengths) in radius. The highest speed of the fish robot was estimated to be approximately 33 mm s-1 (or 0.25 body lengths s-1) and was achieved with a flapping frequency of 0.6-0.8 Hz which also corresponded with the most hydrodynamically efficient mode for tail fin operation. This speed is approximately ten times faster than those for any previously reported artificial muscle based device that also offers real-time speed and directional control. This study contributes to previously published studies on bio-inspired functional devices, demonstrating that electroactive polymer actuators can be real alternatives to conventional means of actuation such as electric motors.

  19. Improved direct torque control of an induction generator used in a wind conversion system connected to the grid.

    Science.gov (United States)

    Abdelli, Radia; Rekioua, Djamila; Rekioua, Toufik; Tounzi, Abdelmounaïm

    2013-07-01

    This paper presents a modulated hysteresis direct torque control (MHDTC) applied to an induction generator (IG) used in wind energy conversion systems (WECs) connected to the electrical grid through a back-to-back converter. The principle of this strategy consists in superposing to the torque reference a triangular signal, as in the PWM strategy, with the desired switching frequency. This new modulated reference is compared to the estimated torque by using a hysteresis controller as in the classical direct torque control (DTC). The aim of this new approach is to lead to a constant frequency and low THD in grid current with a unit power factor and a minimum voltage variation despite the wind variation. To highlight the effectiveness of the proposed method, a comparison was made with classical DTC and field oriented control method (FOC). The obtained simulation results, with a variable wind profile, show an adequate dynamic of the conversion system using the proposed method compared to the classical approaches. PMID:23615169

  20. Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control

    International Nuclear Information System (INIS)

    This paper presents the development of an autonomously powered and controlled robotic fish that incorporates an active flexural joint tail fin, activated through conducting polymer actuators based on polypyrrole (PPy). The novel electromaterial muscle oscillator (NEMO) tail fin assembly on the fish could be controlled wirelessly in real time by varying the frequency and duty cycle of the voltage signal supplied to the PPy bending-type actuators. Directional control was achieved by altering the duty cycle of the voltage input to the NEMO tail fin, which shifted the axis of oscillation and enabled turning of the robotic fish. At low speeds, the robotic fish had a turning circle as small as 15 cm (or 1.1 body lengths) in radius. The highest speed of the fish robot was estimated to be approximately 33 mm s−1 (or 0.25 body lengths s−1) and was achieved with a flapping frequency of 0.6–0.8 Hz which also corresponded with the most hydrodynamically efficient mode for tail fin operation. This speed is approximately ten times faster than those for any previously reported artificial muscle based device that also offers real-time speed and directional control. This study contributes to previously published studies on bio-inspired functional devices, demonstrating that electroactive polymer actuators can be real alternatives to conventional means of actuation such as electric motors

  1. Power Control for Direct-Driven Permanent Magnet Wind Generator System with Battery Storage

    OpenAIRE

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load p...

  2. The microbiome quality control project: baseline study design and future directions

    OpenAIRE

    Sinha, Rashmi; Christian C Abnet; White, Owen; Knight, Rob; Huttenhower, Curtis

    2015-01-01

    Microbiome research has grown exponentially over the past several years, but studies have been difficult to reproduce across investigations. Relevant variation in measurements between laboratories, from a variety of sources, has not been systematically assessed. This is coupled with a growing concern in the scientific community about the lack of reproducibility in biomedical research. The Microbiome Quality Control project (MBQC) was initiated to identify sources of variation in microbiome st...

  3. Engaging Direct Care Providers in Improving Infection Prevention and Control Practices Using Participatory Visual Methods.

    Science.gov (United States)

    Backman, Chantal; Bruce, Natalie; Marck, Patricia; Vanderloo, Saskia

    2016-01-01

    The purpose of this quality improvement project was to determine the feasibility of using provider-led participatory visual methods to scrutinize 4 hospital units' infection prevention and control practices. Methods included provider-led photo walkabouts, photo elicitation sessions, and postimprovement photo walkabouts. Nurses readily engaged in using the methods to examine and improve their units' practices and reorganize their work environment. PMID:26681499

  4. Controllable versus uncontrollable stressors bi-directionally modulate conditioned but not innate fear.

    Science.gov (United States)

    Baratta, M V; Christianson, J P; Gomez, D M; Zarza, C M; Amat, J; Masini, C V; Watkins, L R; Maier, S F

    2007-06-01

    Fear conditioning and fear extinction play key roles in the development and treatment of anxiety-related disorders, yet there is little information concerning experiential variables that modulate these processes. Here we examined the impact of exposure to a stressor in a different environment on subsequent fear conditioning and extinction, and whether the degree of behavioral control that the subject has over the stressor is of importance. Rats received a session of either escapable (controllable) tail shock (ES), yoked inescapable (uncontrollable) tail shock (IS), or control treatment (home cage, HC) 7 days before fear conditioning in which a tone and foot shock were paired. Conditioning was measured 24 h later. In a second experiment rats received ES, IS or HC 24 h after contextual fear conditioning. Extinction then occurred every day beginning 7 days later until a criterion was reached. Spontaneous recovery of fear was assessed 14 days after extinction. IS potentiated fear conditioning when given before fear conditioning, and potentiated fear responding during extinction when given after conditioning. Importantly, ES potently interfered with later fear conditioning, decreased fear responding during fear extinction, and prevented spontaneous recovery of fear. Additionally, we examined if the activation of the ventral medial prefrontal cortex (mPFCv) by ES is critical for the protective effects of ES on later fear conditioning. Inactivation of the mPFCv with muscimol at the time of the initial experience with control prevented ES-induced reductions in later contextual and auditory fear conditioning. Finally, we explored if the protective effects of ES extended to an unconditioned fear stimulus, ferret odor. Unlike conditioned fear, prior ES increased the fear response to ferret odor to the same degree as did IS. PMID:17478046

  5. Controlling roughness: from etching to nanotexturing and plasma-directed organization on organic and inorganic materials

    OpenAIRE

    Gogolides, Evangelos; Tserepi, Angeliki; Constantoudis, Vassilios; Kokkoris, George; Kontziampasis, Dimitrios; Tsougeni, Katerina; Boulousis, George; Vlachopoulou, Marilena

    2011-01-01

    Abstract We describe how plasma-wall interactions in etching plasmas lead to either random roughening / nanotexturing of polymeric and Silicon surfaces, or formation of organized nanostructures on such surfaces. We conduct carefully designed experiments of plasma-wall interactions to understand the causes of both phenomena, and present Monte-Carlo simulation results confirming the experiments. We discuss emerging applications in wetting and optical property control, protein adsorption, mic...

  6. DC Motor Speed and Position Control System Connects Directly to Microcomputer Chips

    OpenAIRE

    Albert Zsolt Barabas; Alexandru Morar

    2011-01-01

    The papers presents a high performance speed and position control system for separately-excited D.C. motor, which was designed and performed with a dedicated integrated circuits (L290, L291, L292), made by SGS-THOMSON Microelectronics Company. The L290, L291 and L292 together form a complete microprocessorcontrolled (microcomputer chips) DC motor servo positioning system that is both fast and accurate with an adequate software . The papers presents a description of the system, detailed functi...

  7. Google Glass-Directed Monitoring and Control of Microfluidic Biosensors and Actuators

    OpenAIRE

    Zhang, Yu Shrike; Busignani, Fabio; Ribas, João; Aleman, Julio; Rodrigues, Talles Nascimento; Shaegh, Seyed Ali Mousavi; Massa, Solange; Rossi, Camilla Baj; Taurino, Irene; Shin, Su-Ryon; Calzone, Giovanni; Amaratunga, Givan Mark; Chambers, Douglas Leon; Jabari, Saman; Niu, Yuxi

    2016-01-01

    Google Glass is a recently designed wearable device capable of displaying information in a smartphone-like hands-free format by wireless communication. The Glass also provides convenient control over remote devices, primarily enabled by voice recognition commands. These unique features of the Google Glass make it useful for medical and biomedical applications where hands-free experiences are strongly preferred. Here, we report for the first time, an integral set of hardware, firmware, softwar...

  8. Direct Deposition of Crystalline Aragonite in the Controlled Biomineralization of the Calcareous Tubeworm

    OpenAIRE

    Chan, Vera B. S.; Toyofuku, Takashi; Wetzel, George; Saraf, Laxmikant; Thiyagarajan, Vengatesen; Mount, Andrew S.

    2015-01-01

    Although space delineation is a well-accepted requirement for biologically controlled biomineralization, the actual location of the mineralizing compartment within marine invertebrates has only recently been determined. We observed that the biomineralization was compartmented within the collar region of the metamorphosing larvae of Hydrodies elegans at its earliest possible time, i.e., at the post-metamorphic stage. We have also found that these highly regulated compartments contained aragoni...

  9. Optimal control of gun recoil in direct fire using magnetorheological absorbers

    Science.gov (United States)

    Singh, Harinder J.; Wereley, Norman M.

    2014-05-01

    Optimal control of a gun recoil absorber is investigated for minimizing recoil loads and maximizing rate of fire. A multi-objective optimization problem was formulated by considering the mechanical model of the recoil absorber employing a spring and a magnetorheological (MR) damper. The damper forces are predicted by evaluating pressure drops using a nonlinear Bingham-plastic model. The optimization methodology provides multiple optimal design configurations with a trade-off between recoil load minimization and increased rate of fire. The configurations with low or high recoil loads imply low or high rate of fire, respectively. The gun recoil absorber performance is also analyzed for perturbations in the firing forces. The adaptive control of the MR damper for varying gun firing forces provides a smooth operation by returning the recoil mass to its battery position (ready to reload and fire) without incurring an end-stop impact. Furthermore, constant load transmissions are observed with respect to the recoil stroke by implementing optimal control during the simulated firing events.

  10. Optimal control of gun recoil in direct fire using magnetorheological absorbers

    International Nuclear Information System (INIS)

    Optimal control of a gun recoil absorber is investigated for minimizing recoil loads and maximizing rate of fire. A multi-objective optimization problem was formulated by considering the mechanical model of the recoil absorber employing a spring and a magnetorheological (MR) damper. The damper forces are predicted by evaluating pressure drops using a nonlinear Bingham-plastic model. The optimization methodology provides multiple optimal design configurations with a trade-off between recoil load minimization and increased rate of fire. The configurations with low or high recoil loads imply low or high rate of fire, respectively. The gun recoil absorber performance is also analyzed for perturbations in the firing forces. The adaptive control of the MR damper for varying gun firing forces provides a smooth operation by returning the recoil mass to its battery position (ready to reload and fire) without incurring an end-stop impact. Furthermore, constant load transmissions are observed with respect to the recoil stroke by implementing optimal control during the simulated firing events. (paper)

  11. Learning techniques to train neural networks as a state selector for inverter-fed induction machines using direct torque control

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera, L.A.; Elbuluk, M.E. [Univ. of Akron, OH (United States). Dept. of Electrical Engineering; Zinger, D.S. [Northern Illinois Univ., Dekalb, IL (United States). Dept. of Electrical Engineering

    1997-09-01

    Neural networks are receiving attention as controllers for many industrial applications. Although these networks eliminate the need for mathematical models, they require a lot of training to understand the model of a plant or a process. Issues such as learning speed, stability, and weight convergence remain as areas of research and comparison of many training algorithms. This paper discusses the application of neural networks to control induction machines using direct torque control (DTC). A neural network is used to emulate the state selector of the DTC. The training algorithms used in this paper are the backpropagation, adaptive neuron model, extended Kalman filter, and the parallel recursive prediction error. Computer simulations of the motor and neural-network system using the four approaches are presented and compared. Discussions about the parallel recursive prediction error and the extended Kalman filter algorithms as the most promising training techniques is presented, giving their advantages and disadvantages.

  12. Sensorless Master-slave Direct Torque Control of Permanent Magnet Synchronous Motors Based on Speed MRAS Observer in Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Kada Hartani

    2014-06-01

    Full Text Available In this study, a new sensorless master slave direct torque control of permanent magnet synchronous motors based on speed MRAS observer is proposed for a multi-machine system in electric vehicle. The speeds of both motors are estimated by using Model Reference Adaptive System (MRAS scheme. A classical system with multi-inverter and multi-machine comprises a three-phase inverter for each machine to be controlled. Another approach consists in using only one three-phase inverter to supply several permanent magnet synchronous machines. A new DTC algorithm is used for the control of bi-machine traction system. Simulation results in MATLAB/SIMULINK indicated that the new DTC algorithm is well adapted for the synchronism of this system over a wide range of operations.

  13. Testing a Crime Control Model: Does Strategic and Directed Deployment of Police Officers Lead to Lower Crime?

    Directory of Open Access Journals (Sweden)

    James P. McElvain

    2013-01-01

    Full Text Available The purpose of the paper was to investigate whether implementation of a crime control model (based, in part, on the concepts of COMPSTAT in one southern California city was effective in reducing crime. Time series regression models were fitted to data collected from the Riverside County Sheriff’s Department, city of Perris, for the years 2000 through 2010. Additional data were collected from three other cities that served as controls. Results showed that the program was effective in reducing crime rates in Perris. The effect remained significant even after taking into account time trends and control cities. Analysis also found that while the program was more effective in lessening total and property crime rates, it was less so for violent crime rates. It was concluded that strategic and directed policing models (e.g., COMPSTAT, hot spot policing, etc. may be more effective in crime reduction efforts than reactive policing methods.

  14. Thermal Test Verification of Emission Control through Directional Baffles for the James Webb Space Telescope

    Science.gov (United States)

    Garrison, Matthew; Rashford, Robert; Switzer, Timothy; Shaw, David; White, Bryant; Lynch, Michael; Huber, Frank; Bachtell, Neal

    2009-01-01

    The thermal performance of NASA s planned James Webb Space Telescope is highly reliant on a collection of directional baffles that are part of the Integrated Science Instrument Module Electronics Compartment. In order to verify the performance of the baffle concept, two test assemblies were recently fabricated and tested at the Goddard Space Flight Center. The centerpiece of the testing was a fixture that used bolometers to measure the emission field through the baffles while the radiator panels and baffles ran a flight-like temperature. Although not all test goals were able to be met due to facility malfunctions, the test was able to prove the design viability enough to gain approval to begin manufacturing the flight article.

  15. Policy issues on the control of major accident hazards and the new Seveso II directive

    International Nuclear Information System (INIS)

    No one wants a major accident to occur! This paper describes the development of EC policies to convert this simple and obvious fact into a coherent prevention strategy which can deliver a high level of protection throughout the European Community. The Seveso II Directive is described in detail, being the relevant Community Instrument which Member States must implement in their national laws. The need to achieve the correct balance between setting general goals and being over prescriptive is discussed, commensurate with the intent to be flexible but yet consistent and effective at the same time. The main changes from Seveso I are discussed, including requirements related to the operator's management systems, the competent authority's systems for inspection, and information and consultation arrangements with the public. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. High-directivity planar antenna using controllable photonic bandgap material at microwave frequencies

    International Nuclear Information System (INIS)

    In this letter, we experimentally demonstrate the capability of a controllable photonic bandgap (CPBG) material to conform the emitted radiation of a planar antenna at 12 GHz. The CPBG material is a variable conductance lattice fabricated with high-frequency PIN diodes soldered along metallic stripes on dielectric printed boards. Depending on the diode bias, the emitted radiation of the antenna can be either transmitted or totally reflected by the material. In the transmission state, the antenna radiation is spatially filtered by the CPBG material in a sharp beam perpendicular to the surface of the material. [copyright] 2001 American Institute of Physics

  17. Directed wet-chemical synthesis of metallic nanoparticles of different sizes and shapes: control mechanisms

    OpenAIRE

    Attia Attia, Yasser

    2012-01-01

    En la actualidad, la nanotecnología ocupa un lugar preferente tanto en lo que se refiere a los importantes retos científicos que tiene planteados, como a las enormes potencialidades de aplicación que ofrece esta disciplina científica. Dentro de esta nueva gran área de investigación, la preparación de los nanomateriales (nanoparticulas, NPs) es uno de sus puntos clave, requiriéndose un perfecto control de su tamaño y forma a escala nanométrica para que puedan ser aplicadas co...

  18. Power control for direct-driven permanent magnet wind generator system with battery storage.

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient. PMID:25050405

  19. Symmetry-directed control of electronic coupling for singlet fission in covalent bis-acene dimers.

    Science.gov (United States)

    Damrauer, Niels H; Snyder, Jamie L

    2015-11-19

    While singlet fission (SF) has developed in recent years within material settings, much less is known about its control in covalent dimers. Such platforms are of fundamental importance and may also find practical use in next-generation dye-sensitized solar cell applications or for seeding SF at interfaces following exciton transport. Here, facile theoretical tools based on Boys localization methods are used to predict diabatic coupling for SF via determination of one-electron orbital coupling matrix elements. The results expose important design rules that are rooted in point group symmetry. For Cs-symmetric dimers, pathways for SF that are mediated by virtual charge transfer excited states destructively interfere with negative impact on the magnitude of diabatic coupling for SF. When dimers have C2 symmetry, constructive interference is enabled for certain readily achievable interchromophore orientations. Three sets of dimers exploiting these ideas are explored: a bis-tetracene pair and two sets of aza-substituted tetracene dimers. Remarkable control is shown. In one aza-substituted set, symmetry has no impact on SF reaction thermodynamics but leads to a 16-fold manipulation in SF diabatic coupling. This translates to a difference of nearly 300 in kSF with the faster of the two dimers (C2) being predicted to undergo the process on a nearly ultrafast 1.5 ps time scale. PMID:26505732

  20. Modelling lymphatic filariasis transmission and control: modelling frameworks, lessons learned and future directions.

    Science.gov (United States)

    Stolk, Wilma A; Stone, Chris; de Vlas, Sake J

    2015-03-01

    Mathematical modelling provides a useful tool for policy making and planning in lymphatic filariasis control programmes, by providing trend forecasts based on sound scientific knowledge and principles. This is now especially true, in view of the ambitious target to eliminate lymphatic filariasis as a public health problem globally by the year 2020 and the short remaining timeline to achieve this. To meet this target, elimination programmes need to be accelerated, requiring further optimization of strategies and tailoring to local circumstances. Insights from epidemiological transmission models provide a useful basis. Two general models of lymphatic filariasis transmission and control are nowadays in use to support decision-making, namely a population-based deterministic model (EPIFIL) and an individual-based stochastic model (LYMFASIM). Model predictions confirm that lymphatic filariasis transmission can be interrupted by annual mass drug administration (MDA), but this may need to be continued much longer than the initially suggested 4-6 years in areas with high transmission intensity or poor treatment coverage. However, the models have not been validated against longitudinal data describing the impact of MDA programmes. Some critical issues remain to be incorporated in one or both of the models to make predictions on elimination more realistic, including the possible occurrence of systematic noncompliance, the risk of emerging parasite resistance to anthelmintic drugs, and spatial heterogeneities. Rapid advances are needed to maximize the utility of models in decision-making for the ongoing ambitious lymphatic filariasis elimination programmes. PMID:25765197