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Sample records for cadherin-2 controls directional

  1. Directional and Attitude Stability Control Kit

    Science.gov (United States)

    2014-07-01

    and Attitude Stability Control Kit Final Progress Report This report outlines progress on the DARPA M3 Program, project “Directional and Attitude ...2 ABSTRACT Number of Papers published in peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Directional and Attitude ...Stability Control Kit Final Progress Report Report Title This report outlines progress on the DARPA M3 Program, project “Directional and Attitude

  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. Controlled quantum teleportation and secure direct communication

    Institute of Scientific and Technical Information of China (English)

    Gao Ting; Yan Feng-Li; Wang Zhi-Xi

    2005-01-01

    We present a controlled quantum teleportation protocol. In the protocol, quantum information of an unknown state of a 2-level particle is faithfully transmitted from a sender Alice to a remote receiver Bob via an initially shared triplet of entangled particles under the control of the supervisor Charlie. The distributed entangled particles shared by Alice, Bob and Charlie function as a quantum information channel for faithful transmission. We also propose a controlled and secure direct communication scheme by means of this teleportation. After ensuring the security of the quantum channel, Alice encodes the secret message directly on a sequence of particle states and transmits them to Bob supervised by Charlie using this controlled quantum teleportation. Bob can read out the encoded message directly by the measurement on his qubit. 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 message between Alice and Bob in the public channel, it is completely secure for controlled and direct secret communication if perfect quantum channel is used. The special feature of this scheme is that the communication between two sides depends on the agreement of a third side to co-operate.

  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. Efficient Controlled Quantum Secure Direct Communication Protocols

    OpenAIRE

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

    2015-01-01

    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...

  6. 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.

  7. 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.

  8. Effects of Paradoxical and Self-Control Directives in Counseling.

    Science.gov (United States)

    Lopez, Frederick G.; Wambach, Cathrine A.

    1982-01-01

    Subjects (N=32) with recurring procrastination problems were assigned to either of two directive interview conditions (paradoxical or self-control) or to a no-interview control condition. Results indicated both directive groups exhibited generally greater improvement over time than controls and that opposing forms of direction promoted different…

  9. Manufacturing Research: Self-Directed Control

    Science.gov (United States)

    1991-01-01

    Knudsen Cell over its entire operating range. A topic of continuing interest in PID controllers is the automatic tuning of the PID parameters that...PID map for the Knudsen Cells was explored using commercial automatic tuning PID controllers and software based tuning algorithms. For a complete state...decisions are made by a Hewlett-Packard HP 1000 computer. The HP 1000 sends its control signals to Barber-Colman PID controllers . We took advantage of

  10. Direct Load Control by AC Frequency Modulation

    DEFF Research Database (Denmark)

    Douglass, Philip James; You, Shi

    2012-01-01

    Fine-grained under frequency load shedding called “demand as a frequency controlled reserve“ (DFCR) has been shown to be a promising method of providingfrequency regulation service from distributed loads [1]. Micro-grids with a large portion of intermittent renewable generation will benefit great...

  11. Spatial control of direct chemical vapor deposition of graphene on silicon dioxide by directional copper dewetting

    NARCIS (Netherlands)

    Beld, van den Wesley T.E.; Berg, van den Albert; Eijkel, Jan C.T.

    2016-01-01

    In this paper we present a method for the spatial control of direct graphene synthesis onto silicon dioxide by controlled dewetting. The dewetting process is controlled through a combination of using a grooved substrate and conducting copper deposition at an angle. The substrate is then treated usin

  12. 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 ...

  13. 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...

  14. Controllability of Weighted and Directed Networks with Nonidentical Node Dynamics

    Directory of Open Access Journals (Sweden)

    Linying Xiang

    2013-01-01

    Full Text Available The concept of controllability from control theory is applied to weighted and directed networks with heterogenous linear or linearized node dynamics subject to exogenous inputs, where the nodes are grouped into leaders and followers. Under this framework, the controllability of the controlled network can be decomposed into two independent problems: the controllability of the isolated leader subsystem and the controllability of the extended follower subsystem. Some necessary and/or sufficient conditions for the controllability of the leader-follower network are derived based on matrix theory and graph theory. In particular, it is shown that a single-leader network is controllable if it is a directed path or cycle, but it is uncontrollable for a complete digraph or a star digraph in general. Furthermore, some approaches to improving the controllability of a heterogenous network are presented. Some simulation examples are given for illustration and verification.

  15. 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.

  16. Strategic directions of government control of national information space

    Directory of Open Access Journals (Sweden)

    Ірина Романівна Боднар

    2015-03-01

    Full Text Available The main directions of state information politics are considered. The legal framework and functioning of national information sphere is analyzed. The basic directions of government control of Ukraine's information space are considered. The approaches to the efficiency of the national information system are proposed

  17. Controlled Directional Growth of TiO2 Nanotubes

    DEFF Research Database (Denmark)

    In, Su-il; Hou, Yidong; Abrams, Billie;

    2010-01-01

    We demonstrate how the anodization direction and growth rate of vertically aligned, highly ordered TiO2 nanotube (NT) arrays can be controlled and manipulated by the local concentration of O-2 in the electrolyte. This leads to the growth of highly active TiO2 NT arrays directly on nonconducting s...

  18. 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 .

  19. Cryptanalysis and improvement of controlled secure direct communication

    Institute of Scientific and Technical Information of China (English)

    Kao Shih-Hung; Hwang Tzonelih

    2013-01-01

    This paper points out that,due to a flaw in the sender's encoding,the receiver in Gao et al.'s controlled quantum secret direct communication (CQSDC) protocol [Chin.Phys.14 (2005),No.5,p.893] can reveal the whole secret message without permission from the controller.An improvement is proposed to avoid this flaw.

  20. 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...

  1. 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...

  2. Beyond Control Panels: Direct Manipulation for Visual Analytics

    Energy Technology Data Exchange (ETDEWEB)

    Endert, Alexander; Bradel, Lauren; North, Chris

    2013-07-19

    Information Visualization strives to provide visual representations through which users can think about and gain insight into information. By leveraging the visual and cognitive systems of humans, complex relationships and phenomena occurring within datasets can be uncovered by exploring information visually. Interaction metaphors for such visualizations are designed to enable users direct control over the filters, queries, and other parameters controlling how the data is visually represented. Through the evolution of information visualization, more complex mathematical and data analytic models are being used to visualize relationships and patterns in data – creating the field of Visual Analytics. However, the expectations for how users interact with these visualizations has remained largely unchanged – focused primarily on the direct manipulation of parameters of the underlying mathematical models. In this article we present an opportunity to evolve the methodology for user interaction from the direct manipulation of parameters through visual control panels, to interactions designed specifically for visual analytic systems. Instead of focusing on traditional direct manipulation of mathematical parameters, the evolution of the field can be realized through direct manipulation within the visual representation – where users can not only gain insight, but also interact. This article describes future directions and research challenges that fundamentally change the meaning of direct manipulation with regards to visual analytics, advancing the Science of Interaction.

  3. 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 its...

  4. Control of directional change after mechanical stimulation in Drosophila

    Directory of Open Access Journals (Sweden)

    Zhou Yating

    2012-10-01

    Full Text Available Abstract Background Proper adjustment of moving direction after external mechanical stimulation is essential for animals to avoid danger (e.g. predators, and thus is vital for survival. This process involves sensory inputs, central processing and motor outputs. Recent studies have made considerable progress in identifying mechanosensitive neurons and mechanosensation receptor proteins. Our understandings of molecular and cellular mechanisms that link mechanosensation with the changes in moving direction, however, remain limited. Results In this study, we investigate the control of movement adjustment in Drosophila. In response to gentle touch at the anterior segments, Drosophila larvae reorient and select a new direction for forward movement. The extent of change in moving direction is correlated with the intensity of tactile stimuli. Sensation of gentle touch requires chordotonal organs and class IV da neurons. Genetic analysis indicates an important role for the evolutionarily conserved immunoglobulin (Ig superfamily protein Turtle (Tutl to regulate touch-initiated directional change. Tutl is required specifically in post-mitotic neurons at larval stage after the completion of embryonic development. Circuit breaking analysis identified a small subset of Tutl-positive neurons that are involved in the adjustment of moving direction. Conclusion We identify Tutl and a small subset of CNS neurons in modulating directional change in response to gentle touch. This study presents an excellent starting point for further dissection of molecular and cellular mechanisms controlling directional adjustment after mechanical stimulation.

  5. Thruster direction controlling of assembled spacecraft based on gimbal suspension

    Institute of Scientific and Technical Information of China (English)

    Hongliang Xu; Hai Huang

    2016-01-01

    The attitude control system design and its control effect are affected considerably by the mass-property pa-rameters of the spacecraft. In the mission of on-orbit servicing, as fuel is expended, or the payloads are added or removed, the center of mass wil be changed in certain axe; conse-quently, some thrusters' directions are deviated from the center of mass (CM) in certain plane. The CM of assembled spacecraft estimation and thruster direction control are studied. Firstly, the attitude dynamics of the assembled spacecraft is established based on the Newton-Euler method. Secondly, the estimation can be identified by the least recursive squares algorithm. Then, a scheme to control the thrusters’ directions is proposed. By using the gimbal instaled at the end of the boom, the angle of the thruster is controled by driving the gimbal; therefore, thrusters can be directed to the CM again. Finaly, numerical simulations are used to verify this scheme. Results of the numerical simulations clearly show that this control scheme is rational and feasible.

  6. 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.

  7. Forming Conditions and Neural Network Control of Continuously Directional Microstructure in Directional Solidification Continuous Casting Process

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Directional solidification continuous casting (DSCC) process is a new manufacturing technology for metal- lic materials which combines advantages of both directional solidification technology and continuous casting technolo- gy. Unlimited long shaped metal with directionally solidifying microstructure can be produced by this process. It is experimentally shown that controlling condition of stable and continuous growth of single crystal structure means the precise control of the location of the S/L interface, which is affected and determined by seven process parameters. Moreover, these parameters are also interacted each other, so the disturbance of any parameters may cause the fail- ure of controlling of S/L interface. In this paper, on the basis of analyzing the forming conditions of continuously di- rectional microstructures in DSCC process, the control model of DSCC procedure by neural network control (NNC) method was proposed and discussed. Combining with the experiments, we first used the computer to simulate the effects of the solidification parameters on destination control variable (S/L interface) and the interactions among these parameters during DSCC procedure. Secondly many training samples necessary for neural network calculation can be obtained through the simulation. Moreover, these samples are inputted into neural network software (NNs) and trained, then the control model can be built up.

  8. Robust direct adaptive fuzzy control for nonlinear MIMO systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Huaguang; ZHANG Mingjun

    2006-01-01

    For a class of nonlinear multi-input multi-output systems with uncertainty, a robust direct adaptive fuzzy control scheme was proposed. The feedback control law and adaptive law for parameters were derived based on Lyapunov design approach. The overall control scheme can guarantee that the tracking error converges in the small neighborhood of origin, and all signals of the closed-loop system are uniformly bounded. The main advantage of the proposed control scheme is that in each subsystem only one parameter vector needs to be adjusted on-line in the adaptive mechanism, and so the on-line computing burden is reduced. In addition, the proposed control scheme is a smooth control with no chattering phenomena. A simulation example was proposed to demonstrate the effectiveness of the proposed control algorithm.

  9. 49 CFR 30.9 - Citizenship: Direct or indirect control.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Citizenship: Direct or indirect control. 30.9 Section 30.9 Transportation Office of the Secretary of Transportation DENIAL OF PUBLIC WORKS CONTRACTS TO SUPPLIERS OF GOODS AND SERVICES OF COUNTRIES THAT DENY PROCUREMENT MARKET ACCESS TO U.S. CONTRACTORS §...

  10. Direct laser additive fabrication system with image feedback control

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, Michelle L. (Albuquerque, NM); Hofmeister, William H. (Nashville, TN); Knorovsky, Gerald A. (Albuquerque, NM); MacCallum, Danny O. (Edgewood, NM); Schlienger, M. Eric (Albuquerque, NM); Smugeresky, John E. (Pleasanton, CA)

    2002-01-01

    A closed-loop, feedback-controlled direct laser fabrication system is disclosed. The feedback refers to the actual growth conditions obtained by real-time analysis of thermal radiation images. The resulting system can fabricate components with severalfold improvement in dimensional tolerances and surface finish.

  11. 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…

  12. Lamellar orientation control in directionally solidified TiAl intermetallics

    Directory of Open Access Journals (Sweden)

    Su Yanqing

    2014-07-01

    Full Text Available TiAl-based alloys are potentially used as high-temperature structural materials with a high specific strength in the range of ~ 900 °C. However, the mechanical properties of TiAl-based alloys are extremely anisotropic with respect to the lamellar orientation of the microstructures. A balance combination of room-temperature ductility and strength can be achieved when the lamellar orientation are aligned parallel to the tensile stress direction. Lamellar orientation control of TiAl-based alloys by directional solidification technique has been widely studied in recent years. Two different directional solidification processes can be used to modify the lamellar Orientation. One is a seeding technique and the other is adjusting the solidification path. This paper reviews the principles of the two methods and their progress. The influence of alloy composition and solidification parameters on lamellar orientation control is also discussed.

  13. Polarization-controlled directional scattering for nanoscopic position sensing

    Science.gov (United States)

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

    2016-04-01

    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. This development is motivated by the rich spectral properties of individual high-refractive-index nanoparticles. Here we take advantage of the interference of their magnetic and electric resonances to achieve strong lateral directionality. For controlled excitation of a spherical silicon nanoantenna, we use tightly focused radially polarized light. The resultant directional emission depends on the antenna's position relative to the focus. This approach finds application as a novel position sensing technique, which might be implemented in modern nanometrology and super-resolution microscopy set-ups. We demonstrate in a proof-of-concept experiment that a lateral resolution in the Ångström regime can be achieved.

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. Directional sensitivity of "first trial" reactions in human balance control.

    Science.gov (United States)

    Oude Nijhuis, Lars B; Allum, John H J; Borm, George F; Honegger, Flurin; Overeem, Sebastiaan; Bloem, Bastiaan R

    2009-06-01

    Support-surface movements are commonly used to examine balance control. Subjects typically receive a series of identical or randomly interspersed multidirectional balance perturbations and the atypical "first trial reaction" (evoked by the first perturbation) is often excluded from further analysis. However, this procedure may obscure vital information about neurophysiological mechanisms associated with the first perturbation and, by analogy, fully unexpected falls. We studied first trial reactions, aiming to clarify their directional impact on postural control and to characterize the underlying neurophysiological substrate. We instructed 36 subjects to maintain balance following support-surface rotations in six different directions. Perturbations in each direction were delivered in blocks, consisting of 10 serial stimuli. Full body kinematics, surface reactive forces, and electromyographic (EMG) responses were recorded. Regardless of direction, for the very first rotation, displacement of the center of mass was 15% larger compared with the ensuing nine identical rotations (P postural instability, mainly due to increased response amplitudes. Although rapid habituation occurs following presentation of identical stimuli, subjects immediately become unstable again when the perturbation direction suddenly changes. Excessive responses due to a failure to combine proprioceptive and vestibular cues effectively may explain this instability seen with first trials, particularly when falling backward.

  19. 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.

  20. 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.

  1. Polarization controlled directional propagation of Bloch surface wave.

    Science.gov (United States)

    Kovalevich, Tatiana; Boyer, Philippe; Suarez, Miguel; Salut, Roland; Kim, Myun-Sik; Herzig, Hans Peter; Bernal, Maria-Pilar; Grosjean, Thierry

    2017-03-06

    Bloch surface waves (BSWs) are recently developing alternative to surface plasmon polaritons (SPPs). Due to dramatically enhanced propagation distance and strong field confinement these surface states can be successfully used in on-chip all-optical integrated devices of increased complexity. In this work we propose a highly miniaturized grating based BSW coupler which is gathering launching and directional switching functionalities in a single element. This device allows to control with polarization the propagation direction of Bloch surface waves at subwavelength scale, thus impacting a large panel of domains such as optical circuitry, function design, quantum optics, etc.

  2. Stepwise multiple test procedures and control of directional errors

    OpenAIRE

    1999-01-01

    One of the most difficult problems occurring with stepwise multiple test procedures for a set of two-sided hypotheses is the control of direc-tional errors if rejection of a hypothesis is accomplished with a directional decision. In this paper we generalize a result for so-called step-down procedures derived by Shaffer to a large class of stepwise or closed multiple test procedures. In a unifying way we obtain results for a large class of order statistics procedures includin...

  3. Controlling death: the false promise of advance directives.

    Science.gov (United States)

    Perkins, Henry S

    2007-07-03

    Advance directives promise patients a say in their future care but actually have had little effect. Many experts blame problems with completion and implementation, but the advance directive concept itself may be fundamentally flawed. Advance directives simply presuppose more control over future care than is realistic. Medical crises cannot be predicted in detail, making most prior instructions difficult to adapt, irrelevant, or even misleading. Furthermore, many proxies either do not know patients' wishes or do not pursue those wishes effectively. Thus, unexpected problems arise often to defeat advance directives, as the case in this paper illustrates. Because advance directives offer only limited benefit, advance care planning should emphasize not the completion of directives but the emotional preparation of patients and families for future crises. The existentialist Albert Camus might suggest that physicians should warn patients and families that momentous, unforeseeable decisions lie ahead. Then, when the crisis hits, physicians should provide guidance; should help make decisions despite the inevitable uncertainties; should share responsibility for those decisions; and, above all, should courageously see patients and families through the fearsome experience of dying.

  4. Shape-Grinding by Direct Position/Force Control

    Science.gov (United States)

    Chen, Guanghua; Xu, Weiwei; Minami, Mamoru

    Based on the analysis of the interaction between a manipulator's hand and a working object, a model representing the constrained dynamics of the robot is first discussed. The constrained forces are expressed by an algebraic function of states, input generalized forces, and the constraint condition, and then a direct position/force controller without force sensor is proposed based on the algebraic relation. To give a grinding system the ability to adapt to any object shape being changed by the grinding, we add a function estimating the constraint condition in real time for the adaptive position/force control. Evaluations through simulations, by fitting the changing constraint surface with spline functions, indicate that reliable position/force control and shape-grinding can be achieved by the proposed controller.

  5. TECHNIQUES ABOUT DIRECT OPTIMIZING CONTROL OF GREEN SAND QUALITY*

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Green sand casting is still a main method in the world at present and it is very significant to develop the technology of controlling green sand quality. A new concept, from contents test to contents control, is advanced. In order to realize the new idea, a new method to on-line test active clay and moisture of green sand - double powers energizing alternately (DPEA) method is put forwards. The principle of the new method is to energize standard sand sample with AC and DC powers and to test the electric parameters, and then, to calculate active clay and moisture of green sand by using artificial neural network (ANN). Based on this new method, a direct optimizing system for controlling green sand quality is developed. Techniques about testing and controlling methods, hardware and software are discussed.

  6. [Application of directed acyclic graphs in control of confounding].

    Science.gov (United States)

    Xiang, R; Dai, W J; Xiong, Y; Wu, X; Yang, Y F; Wang, L; Dai, Z H; Li, J; Liu, A Z

    2016-07-01

    Observational study is a method most commonly used in the etiology study of epidemiology, but confounders, always distort the true causality between exposure and outcome when local inferencing. In order to eliminate these confounding, the determining of variables which need to be adjusted become a key issue. Directed acyclic graph(DAG)could visualize complex causality, provide a simple and intuitive way to identify the confounding, and convert it into the finding of the minimal sufficient adjustment for the control of confounding. On the one hand, directed acyclic graph can choose less variables, which increase statistical efficiency of the analysis. On the other hand, it could help avoiding variables that is not measured or with missing values. In a word, the directed acyclic graph could facilitate the reveal of the real causality effectively.

  7. 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.

  8. A New Approach for Controlling Chaos Based on Direct Optimizing Predictive Control

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    We introduce the predictive control theory into the study of chaos control and propose a direct optimizing predictive control algorithm based on a neural network model. The proposed control system stabilizes the chaotic motion in an unknown chaotic system onto the desired target trajectory. Compared with the existing similar algorithms, the proposed control system has faster response, so it requires much shorter time for the stabilization of the chaotic systems.The proposed approach can control hyperchaos and the algorithm is simple. The convergence of the control algorithm and the stability of the control system can be guaranteed. The theoretic analysis and simulations demonstrate the effectiveness of the algorithm.

  9. Melt Flow Control in the Directional Solidification of Binary Alloys

    Science.gov (United States)

    Zabaras, Nicholas

    2003-01-01

    Our main project objectives are to develop computational techniques based on inverse problem theory that can be used to design directional solidification processes that lead to desired temperature gradient and growth conditions at the freezing front at various levels of gravity. It is known that control of these conditions plays a significant role in the selection of the form and scale of the obtained solidification microstructures. Emphasis is given on the control of the effects of various melt flow mechanisms on the local to the solidification front conditions. The thermal boundary conditions (furnace design) as well as the magnitude and direction of an externally applied magnetic field are the main design variables. We will highlight computational design models for sharp front solidification models and briefly discuss work in progress toward the development of design techniques for multi-phase volume-averaging based solidification models.

  10. Direct-Torque Neuro-Fuzzy Control of Induction Motor

    Institute of Scientific and Technical Information of China (English)

    徐君鹏; CHEN Yan-feng; LI Guo-hou

    2007-01-01

    Fuzzy systems are currently being used in a wide field of industrial and scientific applications. Since the design and especially the optimization process of fuzzy systems can be very time consuming, it is convenient to have algorithms which construct and optimize them automatically. In order to improve the system stability and raise the response speed, a new control scheme, direct-torque neuro-fuzzy control for induction motor drive, was put forward. The design and tuning procedure have been described. Also, the improved stator flux estimation algorithm, which guarantees eccentric estimated flux has been proposed.

  11. 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.

  12. 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.

  13. Direct Torque Control of a Small Wind Turbine with a Sliding-Mode Speed Controller

    Science.gov (United States)

    Sri Lal Senanayaka, Jagath; Karimi, Hamid Reza; Robbersmyr, Kjell G.

    2016-09-01

    In this paper. the method of direct torque control in the presence of a sliding-mode speed controller is proposed for a small wind turbine being used in water heating applications. This concept and control system design can be expanded to grid connected or off-grid applications. Direct torque control of electrical machines has shown several advantages including very fast dynamics torque control over field-oriented control. Moreover. the torque and flux controllers in the direct torque control algorithms are based on hvsteretic controllers which are nonlinear. In the presence of a sliding-mode speed control. a nonlinear control system can be constructed which is matched for AC/DC conversion of the converter that gives fast responses with low overshoots. The main control objectives of the proposed small wind turbine can be maximum power point tracking and soft-stall power control. This small wind turbine consists of permanent magnet synchronous generator and external wind speed. and rotor speed measurements are not required for the system. However. a sensor is needed to detect the rated wind speed overpass events to activate proper speed references for the wind turbine. Based on the low-cost design requirement of small wind turbines. an available wind speed sensor can be modified. or a new sensor can be designed to get the required measurement. The simulation results will be provided to illustrate the excellent performance of the closed-loop control system in entire wind speed range (4-25 m/s).

  14. Induction machine Direct Torque Control system based on fuzzy adaptive control

    Science.gov (United States)

    Li, Shi-ping; Yu, Yan; Jiao, Zhen-gang; Gu, Shu-sheng

    2009-07-01

    Direct Torque Control technology is a high-performance communication control method, it uses the space voltage vector method, and then to the inverter switch state control, to obtain high torque dynamic performance. But none of the switching states is able to generate the exact voltage vector to produce the desired changes in torque and flux in most of the switching instances. This causes a high ripple in torque. To solve this problem, a fuzzy implementation of Direct Torque Control of Induction machine is presented here. Error of stator flux, error of motor electromagnetic torque and position of angle of flux are taken as fuzzy variables. In order to further solve nonlinear problem of variation parameters in direct torque control system, the paper proposes a fuzzy parameter PID adaptive control method which is suitable for the direct torque control of an asynchronous motor. The generation of its fuzzy control is obtained by analyzing and optimizing PID control step response and combining expert's experience. For this reason, it carries out fuzzy work to PID regulator of motor speed to achieve to regulate PID parameters. Therefore the control system gets swifter response velocity, stronger robustness and higher precision of velocity control. The computer simulated results verify the validity of this novel method.

  15. 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.

  16. 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 ...

  17. 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.

  18. Matrix converter controlled with the direct transfer function approach

    DEFF Research Database (Denmark)

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

    2005-01-01

    Power electronics is an emerging technology. New power circuits are invented and have to be introduced into the power electronics curriculum. One of the interesting new circuits is the matrix converter (MC), and this paper analyses its working principles. A simple model is proposed to represent...... the 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...

  19. Research on Direct Torque Control System Based on Induction Motor

    Institute of Scientific and Technical Information of China (English)

    康劲松; 陶生桂; 毛明平

    2003-01-01

    The mathematic model of direct torque control (DTC) was deduced. Two simulating models based on the MATLAB & SIMULINK were established. The emphasis is focused on study of the performance difference of the DTC system with stator flux hexagon and circle trajectories. The simulation waveforms of flux, torque and current characters with two flux trajectories were given. Experiments were carried out in an AC drive system based on induction motor and two-level inverter. A dual-CPU structure was used and the communication with two CPUs was obtained by a dual-port RAM in this system.

  20. Direct Torque Control for Double Star Induction Motor

    OpenAIRE

    LEKHCHINE, SALIMA; BAHI, TAHAR; Soufi, Youcef

    2016-01-01

    This paper describes a direct torque control (DTC) of dual star induction motor (DSIM). This machine possesses several advantages over conventional three-phase machine and is also known as the six-phase induction machine. The research has been underway for the last two decades to investigate the various issues related to the use of six-phase machine as a potential alternative to the conventional three-phase machine. Though six-phase machines have existed for some time, in the literature very ...

  1. 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.

  2. 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.

  3. System for controllable magnetic measurement with direct field determination

    Science.gov (United States)

    Stupakov, O.

    2012-02-01

    This work describes a specially designed setup for magnetic hysteresis and Barkhausen noise measurements. The setup combines two main elements: an improved fast algorithm to control the waveform of magnetic induction and simultaneous direct determination of the magnetic field. The digital feedback algorithm uses only the previous measurement cycle to correct the magnetization voltage without any additional correlation parameter; it usually converges after several tens of cycles. The magnetic field is measured at the sample surface using a vertically mounted array of sensitive Hall sensors. Linear extrapolation of the tangential field profile to the sample surface determines the true waveform of the magnetic field. This unique combination of physically based control for both parameters of the magnetization process provides stable and reliable results, which are independent of a specified experimental configuration. This is illustrated for the industrially attractive measurements of non-oriented electrical steels with a 50 Hz sinusoidal induction waveform.

  4. Direct metal writing: Controlling the rheology through microstructure

    Science.gov (United States)

    Chen, Wen; Thornley, Luke; Coe, Hannah G.; Tonneslan, Samuel J.; Vericella, John J.; Zhu, Cheng; Duoss, Eric B.; Hunt, Ryan M.; Wight, Michael J.; Apelian, Diran; Pascall, Andrew J.; Kuntz, Joshua D.; Spadaccini, Christopher M.

    2017-02-01

    Most metal additive manufacturing approaches are based on powder-bed melting techniques such as laser selective melting or electron beam melting, which often yield uncontrolled microstructures with defects (e.g., pores or microcracks) and residual stresses. Here, we introduce a proof-of-concept prototype of a 3D metal freeform fabrication process by direct writing of metallic alloys in the semi-solid regime. This process is achieved through controlling the particular microstructure and the rheological behavior of semi-solid alloy slurries, which demonstrate a well suited viscosity and a shear thinning property to retain the shape upon printing. The ability to control the microstructure through this method yields a flexible manufacturing route to fabricating 3D metal parts with full density and complex geometries.

  5. Direct Self-Repairing Control for Quadrotor Helicopter Attitude Systems

    Directory of Open Access Journals (Sweden)

    Huiliao Yang

    2014-01-01

    Full Text Available A quadrotor helicopter with uncertain actuator faults, such as loss of effectiveness and lock-in-place, is studied in this paper. An adaptive fuzzy sliding mode controller based on direct self-repairing control is designed for such nonlinear system to track the desired output signal, when any actuator of this quadrotor helicopter is loss of effectiveness or stuck at some place. Moreover, using the Lyapunov stability theory, the stability of the whole system and the convergence of the tracking error can be guaranteed. Finally, the availability of the proposed method is verified by simulation on 3-DOF hover to ensure that the system performance under faulty conditions can be quickly recovered to its normal level. And this proposed method is also proved to be better than that of LQR through simulation.

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. Direct versus Facility Centric Load Control for Automated Demand Response

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Ed; Piette, Mary Ann

    2009-11-06

    Direct load control (DLC) refers to the scenario where third party entities outside the home or facility are responsible for deciding how and when specific customer loads will be controlled in response to Demand Response (DR) events on the electric grid. Examples of third parties responsible for performing DLC may be Utilities, Independent System Operators (ISO), Aggregators, or third party control companies. DLC can be contrasted with facility centric load control (FCLC) where the decisions for how loads are controlled are made entirely within the facility or enterprise control systems. In FCLC the facility owner has more freedom of choice in how to respond to DR events on the grid. Both approaches are in use today in automation of DR and both will continue to be used in future market segments including industrial, commercial and residential facilities. This paper will present a framework which can be used to differentiate between DLC and FCLC based upon where decisions are made on how specific loads are controlled in response to DR events. This differentiation is then used to compare and contrast the differences between DLC and FCLC to identify the impact each has on:(1)Utility/ISO and third party systems for managing demand response, (2)Facility systems for implementing load control, (3)Communications networks for interacting with the facility and (4)Facility operators and managers. Finally a survey of some of the existing DR related specifications and communications standards is given and their applicability to DLC or FCLC. In general FCLC adds more cost and responsibilities to the facilities whereas DLC represents higher costs and complexity for the Utility/ISO. This difference is primarily due to where the DR Logic is implemented and the consequences that creates. DLC may be more certain than FCLC because it is more predictable - however as more loads have the capability to respond to DR signals, people may prefer to have their own control of end-use loads

  11. 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

  12. Improving Myoelectric Control for Amputees through Transcranial Direct Current Stimulation.

    Science.gov (United States)

    Pan, Lizhi; Zhang, Dingguo; Sheng, Xinjun; Zhu, Xiangyang

    2015-08-01

    Most prosthetic myoelectric control studies have shown good performance for unimpaired subjects. However, performance is generally unacceptable for amputees. The primary problem is the poor quality of electromyography (EMG) signals of amputees compared with healthy individuals. To improve clinical performance of myoelectric control, this study explored transcranial direct current stimulation (tDCS) to modulate brain activity and enhance EMG quality. We tested six unilateral transradial amputees by applying active and sham anodal tDCS separately on two different days. Surface EMG signals were acquired from the affected and intact sides for 11 hand and wrist motions in the pre-tDCS and post-tDCS sessions. Autoregression coefficients and linear discriminant analysis classifiers were used to process the EMG data for pattern recognition of the 11 motions. For the affected side, active anodal tDCS significantly reduced the average classification error rate (CER) by 10.1%, while sham tDCS had no such effect. For the intact side, the average CER did not change on the day of sham tDCS but increased on the day of active tDCS. These results demonstrated that tDCS could modulate brain function and improve EMG-based classification performance for amputees. It has great potential in dramatically reducing the length of learning process of amputees for effectively using myoelectrically controlled multifunctional prostheses.

  13. Robust control methods for nonlinear systems with uncertain dynamics and unknown control direction

    Science.gov (United States)

    Ton, Chau T.

    Robust nonlinear control design strategies using sliding mode control (SMC) and integral SMC (ISMC) are developed, which are capable of achieving reliable and accurate tracking control for systems containing dynamic uncertainty, unmodeled disturbances, and actuator anomalies that result in an unknown and time-varying control direction. In order to ease readability of this dissertation, detailed explanations of the relevant mathematical tools is provided, including stability denitions, Lyapunov-based stability analysis methods, SMC and ISMC fundamentals, and other basic nonlinear control tools. The contributions of the dissertation are three novel control algorithms for three different classes of nonlinear systems: single-input multipleoutput (SIMO) systems, systems with model uncertainty and bounded disturbances, and systems with unknown control direction. Control design for SIMO systems is challenging due to the fact that such systems have fewer actuators than degrees of freedom to control (i.e., they are underactuated systems). While traditional nonlinear control methods can be utilized to design controllers for certain classes of cascaded underactuated systems, more advanced methods are required to develop controllers for parallel systems, which are not in a cascade structure. A novel control technique is proposed in this dissertation, which is shown to achieve asymptotic tracking for dual parallel systems, where a single scalar control input directly aects two subsystems. The result is achieved through an innovative sequential control design algorithm, whereby one of the subsystems is indirectly stabilized via the desired state trajectory that is commanded to the other subsystem. The SIMO system under consideration does not contain uncertainty or disturbances. In dealing with systems containing uncertainty in the dynamic model, a particularly challenging situation occurs when uncertainty exists in the input-multiplicative gain matrix. Moreover, special

  14. Achieving HIV-1 Control through RNA-Directed Gene Regulation

    Directory of Open Access Journals (Sweden)

    Vera Klemm

    2016-12-01

    Full Text Available HIV-1 infection has been transformed by combined anti-retroviral therapy (ART, changing a universally fatal infection into a controllable infection. However, major obstacles for an HIV-1 cure exist. The HIV latent reservoir, which exists in resting CD4+ T cells, is not impacted by ART, and can reactivate when ART is interrupted or ceased. Additionally, multi-drug resistance can arise. One alternate approach to conventional HIV-1 drug treatment that is being explored involves gene therapies utilizing RNA-directed gene regulation. Commonly known as RNA interference (RNAi, short interfering RNA (siRNA induce gene silencing in conserved biological pathways, which require a high degree of sequence specificity. This review will provide an overview of the silencing pathways, the current RNAi technologies being developed for HIV-1 gene therapy, current clinical trials, and the challenges faced in progressing these treatments into clinical trials.

  15. 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.

  16. Implementation of Direct Torque Control Scheme for Induction Machines with Variable Structure Controllers

    Institute of Scientific and Technical Information of China (English)

    LI Jian; YANG Geng; WANG Huan'gang; XU Wenli

    2005-01-01

    A torque control scheme for high-performance induction machine drives was developed to over- come some disadvantages of direct torque control (DTC). In the improved DTC method, the stator flux and the torque controllers use variable-structure control theory which does not require information about the rotor speed. Space vector modulation is applied to the voltage source inverter to reduce the torque, stator flux, and current ripples. The digital signal processor-based implementation is described in detail. The experimental results show that the system has good torque and stator flux response with small ripples.

  17. 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.

  18. Ribbon Ion Beam with Controlled Directionality and Local Reactive Chemistry

    Science.gov (United States)

    Biloiu, Costel; Gilchrist, Glen; Kontos, Alex; Basame, Solomon; Rockwell, Tyler; Campbell, Chris; Daniels, Kevin; Allen, Ernest; Wallace, Jay; Ballou, Jon; Hertel, Richard; Chen, Tsung-Liang; Liang, Shurong; Singh, Vikram

    2016-09-01

    A plasma processing technology designed for etch of 3D semiconductor structures is presented. The technology is characterized by controllable ion directionality and local reactive chemistry and it is based on proprietary Applied Materials - Varian Semiconductor Equipment ribbon ion beam architecture. It uses a combination of inert gas ion beam and injection of reactive chemical species at the Point-of-Use (PoU), i.e., at the wafer surface. The ion source uses an inductively coupled plasma source and a diode-type extraction optics. A beam shaping electrode allows extraction of two symmetrical ribbon-like beamlets. The ion beam has in situ controllable ion angular distribution in both mean angle and angular spread. The beam has a uniform distribution of beam current and angles over a waist exceeding 300 mm, allowing full wafer processing in one pass. Chemical compounds are delivered at PoU through linear shower heads. The reactive chemical compound delivered in this fashion maintains its molecular integrity. This result in protection of the trench side walls from deposition of etch residue and facilitates formation of volatile byproducts. The technology was used successfully for mitigation of Magnetic Tunel Junction etch residue. Other applications were this technology differentiate from present technologies are contact liner etch, Co recess, and 1D hole elongation.

  19. Adaptive fuzzy logic controller with direct action type structures for InnoSAT attitude control system

    Science.gov (United States)

    Bakri, F. A.; Mashor, M. Y.; Sharun, S. M.; Bibi Sarpinah, S. N.; Abu Bakar, Z.

    2016-10-01

    This study proposes an adaptive fuzzy controller for attitude control system (ACS) of Innovative Satellite (InnoSAT) based on direct action type structure. In order to study new methods used in satellite attitude control, this paper presents three structures of controllers: Fuzzy PI, Fuzzy PD and conventional Fuzzy PID. The objective of this work is to compare the time response and tracking performance among the three different structures of controllers. The parameters of controller were tuned on-line by adjustment mechanism, which was an approach similar to a PID error that could minimize errors between actual and model reference output. This paper also presents a Model References Adaptive Control (MRAC) as a control scheme to control time varying systems where the performance specifications were given in terms of the reference model. All the controllers were tested using InnoSAT system under some operating conditions such as disturbance, varying gain, measurement noise and time delay. In conclusion, among all considered DA-type structures, AFPID controller was observed as the best structure since it outperformed other controllers in most conditions.

  20. NEURAL NETWORK SPEED CONTROLLER FOR DIRECT VECTOR CONTROL OF INDUCTION MOTORS

    Directory of Open Access Journals (Sweden)

    BEN HAMED MOUNA,

    2010-12-01

    Full Text Available This paper presents a new method for the implementation of a direct rotor flux control (DRFOC of induction motor (IM drives. It is based on the rotor flux components regulation. In fact, the d and q axis flux components feed a proportional integral (PI controller. The outputs of which are the targets start voltages (vdsref andvqsref. While, the synchronous speed is depicted at the output of rotor speed controller. In order to accomplish variable speed operation, conventional PI lie controller is commonly used. This controller provides limited good performances over a wide range of operation even under ideal field oriented conditions. An alternate approach is to use the so called neural network controller. The overall investigated system is implemented using dSpace system based on digital signal processor (DSP. Simulation and experimental results have been presented for one kw IM drives to confirm the validity of the proposed algorithms.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Direct Drive Electro-hydraulic Servo Control System Design with Self-Tuning Fuzzy PID Controller

    Directory of Open Access Journals (Sweden)

    Wang Yeqin

    2013-06-01

    Full Text Available According to the nonlinear and time-varying uncertainty characteristics of direct drive electro-hydraulic servo control system, a self-tuning fuzzy PID control method with speed change integral and differential ahead optimizing operator is put forward by combining fuzzy inference and traditional PID control in this paper.The rule of fuzzy logic is designed, the membership function of the fuzzy subsets is determined and lookup table method is used to correcte the PID parameters in real-time. Finally the simulation is conducted with the typical input signal, such as tracking step, sine etc. The simulation results show that,the self-tuning fuzzy PID control system can effectively improve the dynamic characteristic when the system is out of the range of the operating point compared with the traditional PID control system, there is obvious improvement in the indexes of rapidity, stability and accuracy,  and fuzzy self-tuning PID Control is more robust, and more suitable for direct drive electro-hydraulic servo system.

  8. Media bias under direct and indirect government control: when is the bias smaller?

    OpenAIRE

    Abhra Roy

    2015-01-01

    We present an analytical framework to compare media bias under direct and indirect government control. In this context, we show that direct control can lead to a smaller bias and higher welfare than indirect control. We further show that the size of the advertising market affects media bias only under direct control. Media bias, under indirect control, is not affected by the size of the advertising market.

  9. 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...

  10. 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...

  11. 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...

  12. Directly observed iron supplementation for control of iron deficiency anemia

    Directory of Open Access Journals (Sweden)

    Mohan Bairwa

    2017-01-01

    Full Text Available Anemia is major public health problem affecting 1.6 billion people worldwide. The poor compliance of iron supplementation remains main contributor for high prevalence of anemia. The current paper reviewed the effectiveness of direct observation of oral iron supplementation on anemia. A systematic search was performed through electronic databases and local libraries. Search strategies used subject headings and key words “directly observed” and “iron supplementation.” Searches were sought through April 2014. A total of 14 articles were included in the study. Findings were presented in three categories. First, all of those reported an improvement in compliance of iron supplementation. Second, reduction in the prevalence of anemia was reported by all and third, all except one reported increased blood hemoglobin level. Directly observed an iron supplementation is an effective approach for prevention and management of anemia in vulnerable groups. However, larger trials are needed before concluding that scaling up directly observed iron supplementation through community health volunteers would be beneficial.

  13. 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.

  14. 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.

  15. How do emotion and motivation direct executive control?

    Science.gov (United States)

    Pessoa, Luiz

    2009-04-01

    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 mechanisms and to interact with several other brain structures, including the amygdala and nucleus accumbens, in integrating affectively significant signals with control signals in prefrontal cortex. An implication of the proposal is that emotion and motivation can either enhance or impair behavioral performance depending on how they interact with control functions.

  16. 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...

  17. 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...

  18. Trajectory and Force Control of a Direct Drive Arm.

    Science.gov (United States)

    1986-09-01

    fixed-point arithmetic. Written in the C lan- guage, the controller, including the full computation of the robot dynamics , runs at a 133 Hz sampling...Featherstone, R, 1984, Robot Dynamics Algorithms, Ph.D. Thesis, University of Edinburgh. Franklin, G.F. and Powel, J.D., 1980, Digital Control of Dynamic...Proceedings, 64, pp. 1198-1208. Neuman, C.P., and Khosla, P.K., 1985, "Identification of robot dynamics : an ap- plication of recursive estimation

  19. Direct energy converter controllers for switched reluctance motor operation

    OpenAIRE

    Goodman, Andrew Simon

    2007-01-01

    There is increasing demand for simple motor drives offering high reliability and fault tolerance in applications such as the aerospace actuator industry, with the development of `more electric aircraft'. This thesis presents a motor drive employing a switched reluctance motor, the novel single sided matrix converter, and a novel double band hysteresis based control scheme for control of the converter, implemented using a field programmable gate array (FPGA). The single sided matrix co...

  20. Wind Turbine Extreme Gust Control. Recognition and Control of extreme operation gusts and wind direction changes

    Energy Technology Data Exchange (ETDEWEB)

    Kanev, S.K.; Van Engelen, T.G. [ECN Wind Energy, Petten (Netherlands)

    2008-10-15

    This report presents the research activities and achieved results on extreme event recognition (EER) and control (EEC). This work has been performed within the framework of WP3 of the SenterNovem project Sustainable Control (SusCon). An extreme wind gust with direction change can lead to large loads on the turbine (causing fatigue) and unnecessary turbine shut-downs by the supervisory system due to rotor overspeed. The proposed EER algorithm is based on a nonlinear observer (extended Kalman filter) that estimates the oblique wind inflow angle and the blade effective wind speed signals, which are then used by a detection algorithm (CUSUM test) to recognize extreme events. The nonlinear observer requires that blade root bending moments measurements (in-plane and out-of-plane) are available. Once an extreme event is detected, an EEC algorithm is activated that (1) tries to prevent the rotor speed from exceeding the overspeed limit by fast collective blade pitching, and (2) reduces 1p blade loads by means of individual pitch control algorithm, designed in an H1 optimal control setting. The method is demonstrated on a complex nonlinear test turbine model.

  1. 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.

  2. Direction-specific interactions control crystal growth by oriented attachment

    DEFF Research Database (Denmark)

    Li, Dongsheng; Nielsen, Michael H; Lee, Jonathan R.I.;

    2012-01-01

    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....

  3. 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.

  4. 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.

  5. 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.

  6. Directional sensitivity of "first trial" reactions in human balance control.

    NARCIS (Netherlands)

    Oude Nijhuis, L.B.; Allum, J.H.J.; Borm, G.F.; Honegger, F.; Overeem, S.; Bloem, B.R.

    2009-01-01

    Support-surface movements are commonly used to examine balance control. Subjects typically receive a series of identical or randomly interspersed multidirectional balance perturbations and the atypical "first trial reaction" (evoked by the first perturbation) is often excluded from further analysis.

  7. Goal directed locomotion and balance control in autistic children.

    Science.gov (United States)

    Vernazza-Martin, S; Martin, N; Vernazza, A; Lepellec-Muller, A; Rufo, M; Massion, J; Assaiante, C

    2005-02-01

    This article focuses on postural anticipation and multi-joint coordination during locomotion in healthy and autistic children. Three questions were addressed. (1) Are gait parameters modified in autistic children? (2) Is equilibrium control affected in autistic children? (3) Is locomotion adjusted to the experimenter-imposed goal? Six healthy children and nine autistic children were instructed to walk to a location (a child-sized playhouse) inside the psychomotor room of the pedopsychiatric centre located approximately 5 m in front of them. A kinematic analysis of gait (ELITE system) indicates that, rather than gait parameters or balance control, the main components affected in autistic children during locomotion are the goal of the action, the orientation towards this goal and the definition of the trajectory due probably to an impairment of movement planning.

  8. Simulation of Brushless DC Motor using Direct Torque Control

    OpenAIRE

    Kusuma, G.; 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...

  9. Information Modeling for Direct Control of Distributed Energy Resources

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Andersen, Palle; Stoustrup, Jakob

    2013-01-01

    a desired accumulated response. In this paper, we design such an information model based on the markets that the aggregator participates in and based on the flexibility characteristics of the remote controlled DERs. The information model is constructed in a modular manner making the interface suitable...... for a whole range of different DERs. The devised information model can serve as input to the international standardization efforts on distributed energy resources....

  10. 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.

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

    Science.gov (United States)

    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 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.

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

    DEFF Research Database (Denmark)

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

    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 handle the uncertainties arise from model mismatch, a series of feedback loop are also considered along...

  13. 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.

  14. Real Time Fuzzy Based Speed and Direction Angle Control of an Automated Guided Vehicle

    Directory of Open Access Journals (Sweden)

    Abdullah Başçı

    2015-04-01

    Full Text Available In this paper a fuzzy controller is applied to velocity and direction angle control of a certain type of wheeled mobile robots called Automated Guided Vehicles (AGVs. The velocity and direction angle of the AGV are controlled to keep the vehicle on desired path. A PI controller is also applied to AGV in order to show the robustness of the fuzzy controller. Experimental results prove that the fuzzy controller shows better tracking performance than the PI controller in terms of robustness, smoothness and fast dynamics. Results are also given for sudden disturbance and extra load conditions and satisfied results are obtained.

  15. Direct digital simulation of power semiconductor-controlled electrical machines

    Science.gov (United States)

    Bahnassy, H. M.

    1981-06-01

    Generalized computer programming techniques for simulating power semiconductor-controlled electric machines in coil-variable representation are presented. These techniques are developed primarily for implementation in large scale general purpose computer-aided design and analysis (CADA) circuit programs. To demonstrate the validity of the developed techniques, a coil-variable model of a brushless synchronous generator with an ac exciter and rotating rectifiers was constructed. The performance of the control system (thyristor voltage regulator) is represented by a transfer function block diagram model. The CADA circuit program used is the recently developed SUPER SCEPTRE program. The model is validated using the design data and test results of a 60 kVA brushless generator. Numerous computer simulation cases are presented including the steady state and transient conditions. Brushless generator performance under diode failure faults (opened-diode, shorted-diode) is simulated. The effects of the external faults, at the main generator terminals, on the main generator, as well as its excitation system currents, are simulated.

  16. Polarization controlled directional excitation of Bloch surface waves (Conference Presentation)

    Science.gov (United States)

    Kovalevich, Tatiana; Boyer, Philippe; Bernal, Maria-Pilar; Kim, Myun-Sik; Herzig, Hans Peter; Grosjean, Thierry

    2016-09-01

    Bloch surface waves (BSWs) are electromagnetic surface waves which can be excited at the interface between periodic dielectric multilayer and a surrounding medium. In comparison with surface plasmon polaritons these surface states perform high quality factor due to low loss characteristics of dielectric materials and can be exited both by TE and TM polarized light. A platform consisting of periodic stacks of alternative SiO2 and Si3N4 layers is designed and fabricated to work at the wavelength of 1.55 µm. The platform has an application in sensing and in integrated optics domain. A standard way of BSW excitation is coupling via Kretschmann configuration, but in this work we investigate a grating coupling of BSWs. Grating parameters are analytically and numerically optimized by RCWA and FDTD methods in order to obtain the best coupling conditions. The light is launched orthogonally to the surface of the photonic crystal and the grating. Due to a special grating configuration we demonstrate directionality of the BSW propagation depending on polarization of the incident light. The structure was experimentally realized on the surface of the photonic crystal by FIB milling. Experimental results are in a good agreement with a theory. The investigated configuration can be successfully used as a BSW launcher in on-chip all-optical integrated systems and work as a surface wave switch or modulator.

  17. Loss of lateral prefrontal cortex control in food-directed attention and goal-directed food choice in obesity.

    Science.gov (United States)

    Janssen, Lieneke K; Duif, Iris; van Loon, Ilke; Wegman, Joost; de Vries, Jeanne H M; Cools, Roshan; Aarts, Esther

    2017-02-01

    Loss of lateral prefrontal cortex (lPFC)-mediated attentional control may explain the automatic tendency to eat in the face of food. Here, we investigate the neurocognitive mechanism underlying attentional bias to food words and its association with obesity using a food Stroop task. We tested 76 healthy human subjects with a wide body mass index (BMI) range (19-35kg/m(2)) using fMRI. As a measure of obesity we calculated individual obesity scores based on BMI, waist circumference and waist-to-hip ratio using principal component analyses. To investigate the automatic tendency to overeat directly, the same subjects performed a separate behavioral outcome devaluation task measuring the degree of goal-directed versus automatic food choices. We observed that increased obesity scores were associated with diminished lPFC responses during food attentional bias. This was accompanied by decreased goal-directed control of food choices following outcome devaluation. Together these findings suggest that deficient control of both food-directed attention and choice may contribute to obesity, particularly given our obesogenic environment with food cues everywhere, and the choice to ignore or indulge despite satiety.

  18. 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 und...

  19. Neuromodulatory control of a goal-directed decision.

    Directory of Open Access Journals (Sweden)

    Keiko Hirayama

    Full Text Available 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.

  20. Adaptive fuzzy prescribed performance control for MIMO nonlinear systems with unknown control direction and unknown dead-zone inputs.

    Science.gov (United States)

    Shi, Wuxi; Luo, Rui; Li, Baoquan

    2017-01-01

    In this study, an adaptive fuzzy prescribed performance control approach is developed for a class of uncertain multi-input and multi-output (MIMO) nonlinear systems with unknown control direction and unknown dead-zone inputs. The properties of symmetric matrix are exploited to design adaptive fuzzy prescribed performance controller, and a Nussbaum-type function is incorporated in the controller to estimate the unknown control direction. This method has two prominent advantages: it does not require the priori knowledge of control direction and only three parameters need to be updated on-line for this MIMO systems. It is proved that all the signals in the resulting closed-loop system are bounded and that the tracking errors converge to a small residual set with the prescribed performance bounds. The effectiveness of the proposed approach is validated by simulation results.

  1. Conventional and novel control designs for direct driven PMSG wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuhui; Haskew, Timothy A.; Xu, Ling [Department of Electrical and Computer Engineering, The University of Alabama, 317 Houser Hall, Tuscaloosa, AL 35487 (United States)

    2010-03-15

    With the advance of power electronic technology, direct driven permanent magnet synchronous generators (PMSG) have increasingly drawn interests to wind turbine manufactures. This paper studies and compares conventional and a novel control designs for a direct driven PMSG wind turbine. The paper presents transient and steady-state models of a PMSG system in a d-q reference frame. Then, general PMSG characteristics are investigated in the rotor-flux-oriented frame. A shortage of conventional control mechanisms is studied analytically and through computer simulation. A novel direct-current based d-q vector control technique is proposed by integrating fuzzy, adaptive and traditional PID control technologies in an optimal control configuration. Comparison study demonstrates that the proposed control approach, having superior performance in various aspects, is effective not only in achieving desired PMSG control objectives but also in improving the optimal performance of the overall system. (author)

  2. 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.

  3. A design procedure and handling quality criteria for lateral directional flight control systems

    Science.gov (United States)

    Stein, G.; Henke, A. H.

    1972-01-01

    A practical design procedure for aircraft augmentation systems is described based on quadratic optimal control technology and handling-quality-oriented cost functionals. The procedure is applied to the design of a lateral-directional control system for the F4C aircraft. The design criteria, design procedure, and final control system are validated with a program of formal pilot evaluation experiments.

  4. 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.

  5. 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

  6. Pseudospectral Collocation Methods for the Direct Transcription of Optimal Control Problems

    Science.gov (United States)

    2003-04-01

    solving optimal control problems for trajectory optimization, spacecraft attitude control, jet thruster control, missile guidance and many other... optimal control problems using a pseudospectral direct transcription method. These problems are stated here so that they may be referred to elsewhere...e.g., [7]. 2.3 Prototypical Examples Throughout this thesis two example problems are used to demonstrate various prop- erties associated with solving

  7. 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

  8. Control, Filtering and Prediction for Phased Arrays in Directed Energy Systems

    Science.gov (United States)

    2016-04-30

    AFRL-RD-PS- AFRL-RD-PS- TR-2016-0029 TR-2016-0029 CONTROL, FILTERING AND PREDICTION FOR PHASED ARRAYS IN DIRECTED ENERGY SYSTEMS Steve Gibson...UNLIMITED. AIR FORCE RESEARCH LABORATORY Directed Energy Directorate 3550 Aberdeen Ave SE AIR FORCE MATERIEL COMMAND KIRTLAND AIR FORCE BASE, NM...Filtering and Prediction for Phased Arrays in Directed Energy Systems 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER

  9. 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...

  10. 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.

  11. Architecture control and model identification of a Omni-Directional Mobile Robot

    OpenAIRE

    António Paulo Gomes Mendes Moreira; Paulo José Cerqueira Gomes da Costa; André Gustavo Scolari Conceição

    2005-01-01

    This paper presents a architecture control and model identification of a onmi-Directional Mobile Robot It is divided into the three stages. Stage one proposes a procedure for dynamic model identification and control of the "motor + reduction + encoder" process of the Robotapos;s Motors. Second, proposes the identification of a dynamic model for the whole mobile robot considering it as a multi-variable system. Third, presents a algorithm for perfect trajectory tracking of Omni-Directional Mobi...

  12. 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.

  13. Thinking as the control of imagination: a conceptual framework for goal-directed systems.

    Science.gov (United States)

    Pezzulo, Giovanni; Castelfranchi, Cristiano

    2009-07-01

    This paper offers a conceptual framework which (re)integrates goal-directed control, motivational processes, and executive functions, and suggests a developmental pathway from situated action to higher level cognition. We first illustrate a basic computational (control-theoretic) model of goal-directed action that makes use of internal modeling. We then show that by adding the problem of selection among multiple action alternatives motivation enters the scene, and that the basic mechanisms of executive functions such as inhibition, the monitoring of progresses, and working memory, are required for this system to work. Further, we elaborate on the idea that the off-line re-enactment of anticipatory mechanisms used for action control gives rise to (embodied) mental simulations, and propose that thinking consists essentially in controlling mental simulations rather than directly controlling behavior and perceptions. We conclude by sketching an evolutionary perspective of this process, proposing that anticipation leveraged cognition, and by highlighting specific predictions of our model.

  14. 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.

  15. Optimization of controllability and robustness of complex networks by edge directionality

    Science.gov (United States)

    Liang, Man; Jin, Suoqin; Wang, Dingjie; Zou, Xiufen

    2016-09-01

    Recently, controllability of complex networks has attracted enormous attention in various fields of science and engineering. How to optimize structural controllability has also become a significant issue. Previous studies have shown that an appropriate directional assignment can improve structural controllability; however, the evolution of the structural controllability of complex networks under attacks and cascading has always been ignored. To address this problem, this study proposes a new edge orientation method (NEOM) based on residual degree that changes the link direction while conserving topology and directionality. By comparing the results with those of previous methods in two random graph models and several realistic networks, our proposed approach is demonstrated to be an effective and competitive method for improving the structural controllability of complex networks. Moreover, numerical simulations show that our method is near-optimal in optimizing structural controllability. Strikingly, compared to the original network, our method maintains the structural controllability of the network under attacks and cascading, indicating that the NEOM can also enhance the robustness of controllability of networks. These results alter the view of the nature of controllability in complex networks, change the understanding of structural controllability and affect the design of network models to control such networks.

  16. Information Fusion-Based Optimal Attitude Control for an Alterable Thrust Direction Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Ziyang Zhen

    2013-01-01

    Full Text Available Attitude control is the inner‐loop and the most important part of the automatic flight control system of an unmanned aerial vehicle (UAV. The information fusion‐based optimal control method is applied in a UAV flight control system in this work. Firstly, a nonlinear model of alterable thrust direction UAV (ATD‐UAV is established and linearized for controller design. The longitudinal controller and lateral controller are respectively designed based on information fusion‐based optimal control, and then the information fusion flight control system is built up. Finally, the simulation of a nonlinear model described as ATD‐UAV is carried out, the results of which show the superiority of the information fusion‐based control strategy when compared to the single‐loop design method. We also show that the ATD technique improves the anti‐disturbance capacity of the UAV.

  17. Progress in Aluminum Electrolysis Control and Future Direction for Smart Aluminum Electrolysis Plant

    Science.gov (United States)

    Zhang, Hongliang; Li, Tianshuang; Li, Jie; Yang, Shuai; Zou, Zhong

    2016-10-01

    The industrial aluminum reduction cell is an electrochemistry reactor that operates under high temperatures and highly corrosive conditions. However, these conditions have restricted the measurement of key control parameters, making the control of aluminum reduction cells a difficult problem in the industry. Because aluminum electrolysis control systems have a significant economic influence, substantial research has been conducted on control algorithms, control systems and information systems for aluminum reduction cells. This article first summarizes the development of control systems and then focuses on the progress made since 2000, including alumina concentration control, temperature control and electrolyte molecular ratio control, fault diagnosis, cell condition prediction and control system expansion. Based on these studies, the concept of a smart aluminum electrolysis plant is proposed. The frame construction, key problems and current progress are introduced. Finally, several future directions are discussed.

  18. Managerial span of control: a pilot study comparing departmental complexity and number of direct reports.

    Science.gov (United States)

    Merrill, Katreena Collette; Pepper, Ginette; Blegen, Mary

    2013-09-01

    Nurse managers play pivotal roles in hospitals. However, restructuring has resulted in nurse managers having wider span of control and reduced visibility. The purpose of this pilot study was to compare two methods of measuring span of control: departmental complexity and number of direct reports. Forty-one nurse managers across nine hospitals completed The Ottawa Hospital Clinical Manager Span of Control Tool (TOH-SOC) and a demographic survey. A moderate positive relationship between number of direct reports and departmental complexity score was identified (r=.49, p=<.01). Intensive care departments were more likely to be classified differently, using departmental complexity compared to number of direct reports (54%). TOH-SOC is a reliable instrument (Cronbach's alpha = .838). Using departmental complexity rather than direct reports may more accurately reflect the full scope of nurse managers' responsibility.

  19. Methods of centers and methods of feasible directions for the solution of optimal control problems.

    Science.gov (United States)

    Polak, E.; Mukai, H.; Pironneau, O.

    1971-01-01

    Demonstration of the applicability of methods of centers and of methods of feasible directions to optimal control problems. Presented experimental results show that extensions of Frank-Wolfe (1956), Zoutendijk (1960), and Pironneau-Polak (1971) algorithms for nonlinear programming problems can be quite efficient in solving optimal control problems.

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

    DEFF Research Database (Denmark)

    Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede

    2012-01-01

    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...

  1. Theoretical analysis of a pressure setting and control system with PWM direction control valve

    Science.gov (United States)

    Avram, M.; Duminică, D.; Cartal, L. A.

    2016-08-01

    The paper tackles theoretical aspects concerning an original automated system that sets and controls the pressure inside a tank chamber of fixed volume. The structure of the system integrates an original device developed and designed by the authors. The device digitally controls the one way flow of the working fluid using pulse width modulation, allowing the free flow in the other way. The purpose of this research stage was the theoretical establishing of the variation law of the pressure inside the controlled chamber.

  2. 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...

  3. Global adaptive exponential stabilisation for nonlinear systems with multiple unknown control directions

    Science.gov (United States)

    Sun, Xifang; Chen, Weisheng; Wu, Jian

    2016-12-01

    In this paper, we address the global generalised exponential stabilisation problem for a class of lower-triangular systems with multiple unknown directions. Instead of the well-known Nussbaum-gain adaptive rule, a Lyapunov-based adaptive logic switching rule is proposed to seek the correct control directions for such systems. The main advantage of the proposed controller is that it can guarantee the global generalised exponential stability of closed-loop systems. Simulation examples are given to verify the effectiveness of the developed control approach.

  4. 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.

  5. 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.

  6. 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.

  7. Online process control for directional solidification by ultrasonic pulse echo technique.

    Science.gov (United States)

    Drevermann, A; Pickmann, C; Tiefers, R; Zimmermann, G

    2004-04-01

    A method of controlling the actual growth velocity during directional solidification based on ultrasound has been developed. For this purpose a pulse echo technique is used to measure the actual solidification rate online. This quantity is used to control the furnace velocity. Solidification experiments with metallic alloys and constant furnace velocity often result in non-steady actual solidification rates. Experiments carried out with online process control demonstrate that a really steady-state solidification with a constant solidification rate is achieved.

  8. Direct SQP-methods for solving optimal control problems with delays

    Energy Technology Data Exchange (ETDEWEB)

    Goellmann, L.; Bueskens, C.; Maurer, H.

    1994-12-31

    The maximum principle for optimal control problems with delays leads to a boundary value problem (BVP) which is retarded in the state and advanced in the costate function. Based on shooting techniques, solution methods for this type of BVP have been proposed. In recent years, direct optimization methods have been favored for solving control problems without delays. Direct methods approximate the control and the state over a fixed mesh and solve the resulting NLP-problem with SQP-methods. These methods dispense with the costate function and have shown to be robust and efficient. In this paper, we propose a direct SQP-method for retarded control problems. In contrast to conventional direct methods, only the control variable is approximated by e.g. spline-functions. The state is computed via a high order Runge-Kutta type algorithm and does not enter explicitly the NLP-problem through an equation. This approach reduces the number of optimization variables considerably and is implementable even on a PC. Our method is illustrated by the numerical solution of retarded control problems with constraints. In particular, we consider the control of a continuous stirred tank reactor which has been solved by dynamic programming. This example illustrates the robustness and efficiency of the proposed method. Open questions concerning sufficient conditions and convergence of discretized NLP-problems are discussed.

  9. 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)...

  10. 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.

  11. 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......, oscillations in the power etc. For this reason the integrating action of the speed controller must be limited leading to offsets in the speed control and a poor response to load torque variations. For this reason a load torque estimator is proposed in this paper in order to further improve MPDCC dynamic...... the use of a current controller which takes into account the discrete states of the inverter, e.g. DTC or a more modern approach: Model Predictive Direct Current Control (MPDCC). Moreover overshoots and oscillations in the speed are not desired in many applications, since they lead to mechanical stress...

  12. 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.

  13. 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.

  14. 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

  15. Direct Surge Margin Control for Aeroengines Based on Improved SVR Machine and LQR Method

    Directory of Open Access Journals (Sweden)

    Haibo Zhang

    2013-01-01

    Full Text Available A novel scheme of high stability engine control (HISTEC on the basis of an improved linear quadratic regulator (ILQR, called direct surge margin control, is derived for super-maneuver flights. Direct surge margin control, which is different from conventional control scheme, puts surge margin into the engine closed-loop system and takes surge margin as controlled variable directly. In this way, direct surge margin control can exploit potential performance of engine more effectively with a decrease of engine stability margin which usually happened in super-maneuver flights. For conquering the difficulty that aeroengine surge margin is undetectable, an approach based on improved support vector regression (SVR machine is proposed to construct a surge margin prediction model. The surge margin modeling contains two parts: a baseline model under no inlet distortion states and the calculation for surge margin loss under supermaneuvering flight conditions. The previous one is developed using neural network method, the inputs of which are selected by a weighted feature selection algorithm. Considering the hysteresis between pilot input and angle of attack output, an online scrolling window least square support vector regression (LSSVR method is employed to firstly estimate inlet distortion index and further compute surge margin loss via some empirical look-up tables.

  16. A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical controls.

    Science.gov (United States)

    Zhang, Qinjin; Liu, Yancheng; Zhao, Youtao; Wang, Ning

    2016-03-01

    Multi-mode operation and transient stability are two problems that significantly affect flexible microgrid (MG). This paper proposes a multi-mode operation control strategy for flexible MG based on a three-layer hierarchical structure. The proposed structure is composed of autonomous, cooperative, and scheduling controllers. Autonomous controller is utilized to control the performance of the single micro-source inverter. An adaptive sliding-mode direct voltage loop and an improved droop power loop based on virtual negative impedance are presented respectively to enhance the system disturbance-rejection performance and the power sharing accuracy. Cooperative controller, which is composed of secondary voltage/frequency control and phase synchronization control, is designed to eliminate the voltage/frequency deviations produced by the autonomous controller and prepare for grid connection. Scheduling controller manages the power flow between the MG and the grid. The MG with the improved hierarchical control scheme can achieve seamless transitions from islanded to grid-connected mode and have a good transient performance. In addition the presented work can also optimize the power quality issues and improve the load power sharing accuracy between parallel VSIs. Finally, the transient performance and effectiveness of the proposed control scheme are evaluated by theoretical analysis and simulation results.

  17. An international track wheelchair with a center of gravity directional controller.

    Science.gov (United States)

    Cooper, R A

    1989-01-01

    An international track wheelchair (ITWC) with a center of gravity directional controller (COGDC) is described in this paper. The rules for international track competition disallow devices designed solely for steering. Equipment has been disqualified for having steering handles, crown compensators, and other lever systems. However, the rules do allow tie-rod linkage and the use of springs for dampening caster flutter. The chair described in this paper exploits the physical properties of wheeled vehicles to achieve directional control on the track. This controller is effective, because turning is only required in one direction. Three such track wheelchairs have been developed and were used at the Paralympics in Seoul, Korea, in October of 1988.

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

    OpenAIRE

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

    2015-01-01

    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 ...

  19. 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.

  20. 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.

  1. Control of dendrite growth by a magnetic field during directional solidification

    Science.gov (United States)

    Dai, Yanchao; Du, Dafan; Hou, Long; Gagnoud, Annie; Ren, Zhongming; Fautrelle, Yves; Moreau, Rene; Li, Xi

    2016-04-01

    In this work, the alignment behavior of three kinds of dendrites (Al3Ni, α-Al and Al2Cu dendrites) with a remarkable crystalline anisotropy during directional solidification under an axial magnetic field is studied by the EBSD technology. Experimental results reveal that the magnetic field is capable of tailoring the dendrite alignment during directional solidification. Further, based on the crystalline anisotropy, a method to control the dendrite alignment by adjusting the angle between the magnetic field and the solidification direction is proposed.

  2. The controlled placement and delayed polymerization technique for the direct Class 2 posterior composite restoration.

    Science.gov (United States)

    Atlas, Alan M

    2005-11-01

    Adhesion dentistry and its application to the direct posterior composite restoration is the most controversial topic in dentistry today. The concepts behind this procedure are now the backbone of restorative dentistry. Adhesion dentistry influences basic fillings, crown buildups, post-and-core restorations, cementation, orthodontics, and endodontics. Yet, controversy remains about the correct way to place a direct Class 2 posterior composite restoration. This article will examine the scientific evidence to determine which materials and placement techniques will achieve the optimum direct Class 2 posterior composite restoration at or below the cementoenamel junction using the controlled placement and delayed polymerization technique.

  3. The solution of singular optimal control problems using direct collocation and nonlinear programming

    Science.gov (United States)

    Downey, James R.; Conway, Bruce A.

    1992-08-01

    This paper describes work on the determination of optimal rocket trajectories which may include singular arcs. In recent years direct collocation and nonlinear programming has proven to be a powerful method for solving optimal control problems. Difficulties in the application of this method can occur if the problem is singular. Techniques exist for solving singular problems indirectly using the associated adjoint formulation. Unfortunately, the adjoints are not a part of the direct formulation. It is shown how adjoint information can be obtained from the direct method to allow the solution of singular problems.

  4. Direct and Indirect Couplings in Coherent Feedback Control of Linear Quantum Systems

    CERN Document Server

    Zhang, Guofeng

    2010-01-01

    The purpose of this paper is to study and design direct and indirect couplings for use in coherent feedback control of a class of linear quantum stochastic systems. A general physical model for a nominal linear quantum system coupled directly and indirectly to external systems is presented. Fundamental properties of stability, dissipation, passivity, and gain for this class of linear quantum models are presented and characterized using complex Lyapunov equations and linear matrix inequalities (LMIs). Coherent $H^\\infty$ and LQG synthesis methods are extended to accommodate direct couplings using multistep optimization. Examples are given to illustrate the results.

  5. Improvement of Direct Torque Control by using a Space Vector Modulation Control of Three-Level Inverter

    Science.gov (United States)

    Achalhi, A.; Bezza, M.; Belbounaguia, N.; Boujoudi, B.

    2017-03-01

    The performances of Direct Torque Control (DTC) of Induction machine are highly related to the inverter used therewith. The purpose of this paper is to highlight the efficiency of the space vector modulation (SVM) control of three level inverter associated with the direct torque control. The first part of this work is devoted to present the mathematical models of the DTC associated with 2-levels inverter then 3-levels inverter. Simulations on Matlab/Simulink will allow a comparative study to highlight advantages of the use of three levels inverter. The second part is devoted to the improvement of the DTC associated with a 3-levels inverter by application of the space vector modulation strategy (SVM) in order to manage the switching frequency and reduce harmonics. The efficiency of this solution will be attested by simulation on Matlab/Simulink.

  6. Formation Control for Unmanned Aerial Vehicles with Directed and Switching Topologies

    Directory of Open Access Journals (Sweden)

    Yahui Qi

    2016-01-01

    Full Text Available Formation control problems for unmanned aerial vehicle (UAV swarm systems with directed and switching topologies are investigated. A general formation control protocol is proposed firstly. Then, by variable transformation, the formation problem is transformed into a consensus problem, which can be solved by a novel matrix decomposition method. Sufficient conditions to achieve formation with directed and switching topologies are provided and an explicit expression of the formation reference function is given. Furthermore, an algorithm to design the gain matrices of the protocol is presented. Finally, numerical simulations are provided to illustrate the effectiveness of the theoretical results.

  7. 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.

  8. DISTRIBUTED CONTROL ARCHITECTURE OF AN OMNI-DIRECTIONAL AUTONOMOUS GUIDED VEHICLE

    Directory of Open Access Journals (Sweden)

    N.S. Tlale

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Omni-directionality is the ability of a mobile robot to move instantaneously in any direction. This paper describes the wheel and controller designs of a Mecanumwheeled, autonomous guided vehicle (AGV for reconfigurable manufacturing systems. Mecanum wheels use slip developed between rollers and surface, surface and ground, to achieve omni-directionality. An advantage of omni-directional robotic platforms is that they are capable of performing tasks in congested environments such as those found in factory workshops, narrow aisles, warehouses, etc. Controller Area Network (CAN is implemented as a distributed controller to control motion and navigation tasks of the developed robot. The design of the distributed controller is described and its performance analyzed. This increases the reliability and functionality of the mobile robot.

    AFRIKAANSE OPSOMMING: Die artikel beskryf wiel - en beheerontwerpe van ‘n veelrigting mobiele robot. Die robot is ‘n selfstandigbeheerde voertuig vir gebruik by vervaardigingstelsels met veranderbare konfigurasie. Die ontwerp van die robot en bypassende beheerstelsel word beskryf en ontleed teen die agterground van bewegings – en navigeertake. Die betroubaarheid en funksionering van die sisteem word beoordeel.

  9. 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.

  10. 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.

  11. Demand Controlled Economizer Cycles: A Direct Digital Control Scheme for Heating, Ventilating, and Air Conditioning Systems,

    Science.gov (United States)

    1984-05-01

    includes a heating coil and thermostatic control to maintain the air in this path at an elevated temperature, typically around 80 degrees Farenheit (80 F...1238 Aug 1 1236 1237 52 1074 1126 50 1033 1083 Sep 8 8 5W 862 7T 600 678 75 603 7r Oct 51 400 451 119 204 323 115 207 322 ov 64 123 287 187 71 258

  12. Encoderless direct torque controller for limited speed range applications of brushless doubly-fed reluctance motors

    OpenAIRE

    Jovanovic, Milutin; Levi, Emil; Yu, James

    2006-01-01

    Presents the experimental verification of a new sensor-less control algorithm for direct torque (and flux) control (DTC) of the BDFRM in low variable frequency applications (e.g. wind energy conversion systems) where the low cost potential of the machine can be best exploited by using partially-rated power electronics. Brings a significant contribution to knowledge in the subject field as the proposed scheme has many important advantages over its counterparts in the target applications. Repre...

  13. 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)

  14. Direct control and characterization of a Schottky barrier by scanning tunneling microscopy

    Science.gov (United States)

    Bell, L. D.; Kaiser, W. J.; Hecht, M. H.; Grunthaner, F. J.

    1988-01-01

    Scanning tunneling microscopy (STM) methods are used to directly control the barrier height of a metal tunnel tip-semiconductor tunnel junction. Barrier behavior is measured by tunnel current-voltage spectroscopy and compared to theory. A unique surface preparation method is used to prepare a low surface state density Si surface. Control of band bending with this method enables STM investigation of semiconductor subsurface properties.

  15. A novel speed sensor-less direct torque control system for mining locomotive haulage

    Institute of Scientific and Technical Information of China (English)

    马宪民

    2002-01-01

    A novel speed sensor-less 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 real-time TMS320F240 digital signal processor. The simulation study and experiment results indicate that the suggested system has good performance.

  16. 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.

  17. 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.

  18. State feedback integral control for a rotary direct drive servo valve using a Lyapunov function approach.

    Science.gov (United States)

    Yu, Jue; Zhuang, Jian; Yu, Dehong

    2015-01-01

    This paper concerns a state feedback integral control using a Lyapunov function approach for a rotary direct drive servo valve (RDDV) while considering parameter uncertainties. Modeling of this RDDV servovalve reveals that its mechanical performance is deeply influenced by friction torques and flow torques; however, these torques are uncertain and mutable due to the nature of fluid flow. To eliminate load resistance and to achieve satisfactory position responses, this paper develops a state feedback control that integrates an integral action and a Lyapunov function. The integral action is introduced to address the nonzero steady-state error; in particular, the Lyapunov function is employed to improve control robustness by adjusting the varying parameters within their value ranges. This new controller also has the advantages of simple structure and ease of implementation. Simulation and experimental results demonstrate that the proposed controller can achieve higher control accuracy and stronger robustness.

  19. Trajectory Control:Directional MWD Inversely New Wellbore Positioning Accuracy Prediction Method

    Institute of Scientific and Technical Information of China (English)

    Ahmed Abd Alaziz Ibrahim; Tagwa Ahmed Musa

    2004-01-01

    The deviation control of directional drilling is essentially the controlling of two angles of the wellbore actually drilled, namely, the inclination and azimuth. In directional drilling the bit trajectory never coincides exactly with the planned path, which is usually a plane curve with straight, building, holding, and dropping sections in succession. The drilling direction is of course dependant on the direction of the resultant forces acting on the bit and it is quite a tough job to hit the optimum target at the hole bottom as required. The traditional passive methods for correcting the drilling path have not met the demand to improve the techniques of deviation control. A method for combining wellbore surveys to obtain a composite, more accurate well position relies on accepting the position of the well from the most accurate survey instrument used in a given section of the wellbore. The error in each position measurement is the sum of many independent root sources of error effects. The relationship between surveys and other influential factors is considered, along with an analysis of different points of view. The collaborative work describes, establishes a common starting point of wellbore position uncertainty model, definition of what constitutes an error model, mathematics of position uncertainty calculation and an error model for basic directional service.

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

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2015-01-01

    Full Text Available 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 modeled and a backpropagation artificial neural network is designed to estimate the wind speed loaded into the turbine model in real time through the estimated turbine shaft speed and mechanical power. The nonlinear wind turbine system is presented by multiple linear models. The desired trajectory of the nonlinear system is decomposed to be suitable for the reference trajectory of multiple models that are presented by the linear models of the nonlinear system, which simplifies the nonlinear optimization problems and decreases the calculation difficulty. Then a multivariable control strategy based on model predictive control techniques for the control of variable-speed variable-pitch wind turbines is proposed. Finally, simulation results are given to illustrate the effectiveness of the proposed strategy, and the conclusion that multiple model predictive controller (MMPC has better control performance than the PI control method is obtained.

  1. 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.

  2. Prickle isoforms control the direction of tissue polarity by microtubule independent and dependent mechanisms

    Science.gov (United States)

    Sharp, Katherine A.; Axelrod, Jeffrey D.

    2016-01-01

    ABSTRACT Planar cell polarity signaling directs the polarization of cells within the plane of many epithelia. While these tissues exhibit asymmetric localization of a set of core module proteins, in Drosophila, more than one mechanism links the direction of core module polarization to the tissue axes. One signaling system establishes a polarity bias in the parallel, apical microtubules upon which vesicles containing core proteins traffic. Swapping expression of the differentially expressed Prickle isoforms, Prickle and Spiny-legs, reverses the direction of core module polarization. Studies in the proximal wing and the anterior abdomen indicated that this results from their differential control of microtubule polarity. Prickle and Spiny-legs also control the direction of polarization in the distal wing (D-wing) and the posterior abdomen (P-abd). We report here that this occurs without affecting microtubule polarity in these tissues. The direction of polarity in the D-wing is therefore likely determined by a novel mechanism independent of microtubule polarity. In the P-abd, Prickle and Spiny-legs interpret at least two directional cues through a microtubule-polarity-independent mechanism. PMID:26863941

  3. Prickle isoforms control the direction of tissue polarity by microtubule independent and dependent mechanisms.

    Science.gov (United States)

    Sharp, Katherine A; Axelrod, Jeffrey D

    2016-02-10

    Planar cell polarity signaling directs the polarization of cells within the plane of many epithelia. While these tissues exhibit asymmetric localization of a set of core module proteins, in Drosophila, more than one mechanism links the direction of core module polarization to the tissue axes. One signaling system establishes a polarity bias in the parallel, apical microtubules upon which vesicles containing core proteins traffic. Swapping expression of the differentially expressed Prickle isoforms, Prickle and Spiny-legs, reverses the direction of core module polarization. Studies in the proximal wing and the anterior abdomen indicated that this results from their differential control of microtubule polarity. Prickle and Spiny-legs also control the direction of polarization in the distal wing (D-wing) and the posterior abdomen (P-abd). We report here that this occurs without affecting microtubule polarity in these tissues. The direction of polarity in the D-wing is therefore likely determined by a novel mechanism independent of microtubule polarity. In the P-abd, Prickle and Spiny-legs interpret at least two directional cues through a microtubule-polarity-independent mechanism.

  4. Prickle isoforms control the direction of tissue polarity by microtubule independent and dependent mechanisms

    Directory of Open Access Journals (Sweden)

    Katherine A. Sharp

    2016-03-01

    Full Text Available Planar cell polarity signaling directs the polarization of cells within the plane of many epithelia. While these tissues exhibit asymmetric localization of a set of core module proteins, in Drosophila, more than one mechanism links the direction of core module polarization to the tissue axes. One signaling system establishes a polarity bias in the parallel, apical microtubules upon which vesicles containing core proteins traffic. Swapping expression of the differentially expressed Prickle isoforms, Prickle and Spiny-legs, reverses the direction of core module polarization. Studies in the proximal wing and the anterior abdomen indicated that this results from their differential control of microtubule polarity. Prickle and Spiny-legs also control the direction of polarization in the distal wing (D-wing and the posterior abdomen (P-abd. We report here that this occurs without affecting microtubule polarity in these tissues. The direction of polarity in the D-wing is therefore likely determined by a novel mechanism independent of microtubule polarity. In the P-abd, Prickle and Spiny-legs interpret at least two directional cues through a microtubule-polarity-independent mechanism.

  5. Control of Transposon-Mediated Directed Mutation by the Escherichia coli Phosphoenolpyruvate:Sugar Phosphotransferase System.

    Science.gov (United States)

    Saier, Milton H; Zhang, Zhongge

    2015-01-01

    The phosphoenolpyruvate:sugar phosphotransferase system (PTS) has been shown to control transport, cell metabolism and gene expression. We here present results supporting the novel suggestion that in certain instances it also regulates the mutation rate. Directed mutations are defined as mutations that occur at higher frequencies when beneficial than when neutral or detrimental. To date, the occurrence of directed point mutations has not been documented and confirmed, but a few examples of transposon-mediated directed mutations have been reported. Here we focus on the first and best-studied example of directed mutation, which involves the regulation of insertion sequence-5 hopping into a specific site upstream of the glpFK glycerol utilization operon in Escherichia coli. This insertional event specifically activates expression of the glpFK operon, allowing the growth of wild-type cells with glycerol as a carbon source in the presence of nonmetabolizable glucose analogues which normally block glycerol utilization. The sugar-transporting PTS controls this process by regulating levels of cytoplasmic glycerol-3-phosphate and cyclic (c)AMP as established in previous publications. Direct involvement of the glycerol repressor, GlpR, and the cAMP receptor protein, Crp, in the regulation of transposon-mediated directed mutation has been demonstrated.

  6. 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…

  7. 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...

  8. 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.;

    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....

  9. State University of New York Research Foundation: Controls over Direct Costs. Report 93-S-64.

    Science.gov (United States)

    New York State Office of the Comptroller, Albany. Div. of Management Audit.

    An evaluation was done of the State University of New York (SUNY) Research Foundation's controls over direct expenditures for research and sponsored activities. The Foundation is a private, non-profit educational corporation established to expand the educational mission of SUNY through fund raising, administration of gifts and grants, and…

  10. 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;

    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...

  11. Modeling Human Control of Self-Motion Direction With Optic Flow and Vestibular Motion.

    Science.gov (United States)

    Zaal, Peter M T; Nieuwenhuizen, Frank M; van Paassen, Marinus M; Mulder, Max

    2013-04-01

    In this paper, we investigate the effects of visual and motion stimuli on the manual control of one's direction of self-motion. In a flight simulator, subjects conducted an active target-following disturbance-rejection task, using a compensatory display. Simulating a vehicular control task, the direction of vehicular motion was shown on the outside visual display in two ways: an explicit presentation using a symbol and an implicit presentation, namely, through the focus of radial outflow that emerges from optic flow. In addition, the effects of the relative strength of congruent vestibular motion cues were investigated. The dynamic properties of human visual and vestibular motion perception paths were modeled using a control-theoretical approach. As expected, improved tracking performance was found for the configurations that explicitly showed the direction of self-motion. The human visual time delay increased with approximately 150 ms for the optic flow conditions, relative to explicit presentations. Vestibular motion, providing higher order information on the direction of self-motion, allowed subjects to partially compensate for this visual perception delay, improving performance. Parameter estimates of the operator control model show that, with vestibular motion, the visual feedback becomes stronger, indicating that operators are more confident to act on optic flow information when congruent vestibular motion cues are present.

  12. 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.

  13. 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

  14. Control of roll and pitch motion during multi-directional balance perturbations.

    NARCIS (Netherlands)

    Kung, U.M.; Horlings, C.G.; Honegger, F.; Duysens, J.E.J.; Allum, J.H.J.

    2009-01-01

    Does the central nervous system (CNS) independently control roll and pitch movements of the human body during balance corrections? To help provide an answer to this question, we perturbed the balance of 16 young healthy subjects using multi-directional rotations of the support surface. All rotations

  15. Direct chemical vapour deposited grapheme synthesis on silicon oxide by controlled copper dewettting

    NARCIS (Netherlands)

    Beld, van den Wesley T.E.; Berg, van den Albert; Eijkel, Jan C.T.

    2015-01-01

    In this paper we present a novel method for direct uniform graphene synthesis onto silicon oxide in a controlled manner. On a grooved silicon oxide wafer is copper deposited under a slight angle and subsequently the substrate is treated by a typical graphene synthesis process. During this process di

  16. 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.

  17. Direct power control of DFIG wind turbine systems based on an intelligent proportional-integral sliding mode control.

    Science.gov (United States)

    Li, Shanzhi; Wang, Haoping; Tian, Yang; Aitouch, Abdel; Klein, John

    2016-09-01

    This paper presents an intelligent proportional-integral sliding mode control (iPISMC) for direct power control of variable speed-constant frequency wind turbine system. This approach deals with optimal power production (in the maximum power point tracking sense) under several disturbance factors such as turbulent wind. This controller is made of two sub-components: (i) an intelligent proportional-integral module for online disturbance compensation and (ii) a sliding mode module for circumventing disturbance estimation errors. This iPISMC method has been tested on FAST/Simulink platform of a 5MW wind turbine system. The obtained results demonstrate that the proposed iPISMC method outperforms the classical PI and intelligent proportional-integral control (iPI) in terms of both active power and response time.

  18. Adaptive fuzzy output-feedback controller design for nonlinear time-delay systems with unknown control direction.

    Science.gov (United States)

    Hua, Chang-Chun; Wang, Qing-Guo; Guan, Xin-Ping

    2009-04-01

    In this paper, the robust-control problem is investigated for a class of uncertain nonlinear time-delay systems via dynamic output-feedback approach. The considered system is in the strict-feedback form with unknown control direction. A full-order observer is constructed with the gains computed via linear matrix inequality at first. Then, with the bounds of uncertain functions known, we design the dynamic output-feedback controller such that the closed-loop system is asymptotically stable. Furthermore, when the bound functions of uncertainties are not available, the adaptive fuzzy-logic system is employed to approximate the uncertain function, and the corresponding output-feedback controller is designed. It is shown that the resulting closed-loop system is stable in the sense of semiglobal uniform ultimate boundedness. Finally, simulations are done to verify the feasibility and effectiveness of the obtained theoretical results.

  19. Direct Adaptive Soft Computing Neural Control of a Continuous Bioprocess via Second Order Learning

    Science.gov (United States)

    Baruch, Ieroham; Mariaca-Gaspar, Carlos-Roman; Barrera-Cortes, Josefina

    This paper proposes a new Kalman Filter Recurrent Neural Network (KFRNN) topology and a recursive Levenberg-Marquardt (L-M) second order learning algorithm capable to estimate parameters and states of highly nonlinear bioprocess in a noisy environment. The proposed KFRNN identifier, learned by the Backpropagation and L-M learning algorithm, was incorporated in a direct adaptive neural control scheme. The proposed control scheme was applied for real-time soft computing identification and control of a continuous stirred tank bioreactor model, where fast convergence, noise filtering and low mean squared error of reference tracking were achieved.

  20. Output-feedback adaptive neural control for stochastic nonlinear time-varying delay systems with unknown control directions.

    Science.gov (United States)

    Li, Tieshan; Li, Zifu; Wang, Dan; Chen, C L Philip

    2015-06-01

    This paper presents an adaptive output-feedback neural network (NN) control scheme for a class of stochastic nonlinear time-varying delay systems with unknown control directions. To make the controller design feasible, the unknown control coefficients are grouped together and the original system is transformed into a new system using a linear state transformation technique. Then, the Nussbaum function technique is incorporated into the backstepping recursive design technique to solve the problem of unknown control directions. Furthermore, under the assumption that the time-varying delays exist in the system output, only one NN is employed to compensate for all unknown nonlinear terms depending on the delayed output. Moreover, by estimating the maximum of NN parameters instead of the parameters themselves, the NN parameters to be estimated are greatly decreased and the online learning time is also dramatically decreased. It is shown that all the signals of the closed-loop system are bounded in probability. The effectiveness of the proposed scheme is demonstrated by the simulation results.

  1. Decentralized attitude synchronization tracking control for multiple spacecraft under directed communication topology

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhong; Xu Ying; Zhang Lisong; Song Shenmin

    2016-01-01

    This paper studies the attitude synchronization tracking control of spacecraft formation flying with a directed communication topology and presents three different controllers. By introduc-ing a novel error variable associated with rotation matrix, a decentralized attitude synchronization controller, which could obtain almost global asymptotical stability of the closed-loop system, is developed. Then, considering model uncertainties and unknown external disturbances, we propose a robust adaptive attitude synchronization controller by designing adaptive laws to estimate the unknown parameters. After that, the third controller is proposed by extending this method to the case of time-varying communication delays via Lyapunov–Krasovskii analysis. The distinctive feature of this work is to address attitude coordinated control with model uncertainties, unknown disturbances and time-varying delays in a decentralized framework, with a strongly connected direc-ted information flow. It is shown that tracking and synchronization of an arbitrary desired attitude can be achieved when the stability condition is satisfied. Simulation results are provided to demon-strate the effectiveness of the proposed control schemes.

  2. A semi-analytical direct optimal control solution for strongly excited and dissipative Hamiltonian systems

    Science.gov (United States)

    Ying, Zu-guang; Luo, Yin-miao; Zhu, Wei-qiu; Ni, Yi-qing; Ko, Jan-ming

    2012-04-01

    A semi-analytical direct optimal control solution for strongly excited and dissipative Hamiltonian systems is proposed based on the extended Hamiltonian principle, the Hamilton-Jacobi-Bellman (HJB) equation and its variational integral equation, and the finite time element approximation. The differential extended Hamiltonian equations for structural vibration systems are replaced by the variational integral equation, which can preserve intrinsic system structure. The optimal control law dependent on the value function is determined by the HJB equation so as to satisfy the overall optimality principle. The partial differential equation for the value function is converted into the integral equation with variational weighting. Then the successive solution of optimal control with system state is designed. The two variational integral equations are applied to sequential time elements and transformed into the algebraic equations by using the finite time element approximation. The direct optimal control on each time element is obtained respectively by solving the algebraic equations, which is unconstrained by the system state observed. The proposed control algorithm is applicable to linear and nonlinear systems with the quadratic performance index, and takes into account the effects of external excitations measured on control. Numerical examples are given to illustrate the optimal control effectiveness.

  3. An optimal control method for maximizing the efficiency of direct drive ocean wave energy extraction system.

    Science.gov (United States)

    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 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.

  4. Improved direct power control of a grid-connected voltage source converter during network unbalance

    Institute of Scientific and Technical Information of China (English)

    Peng ZHOU; Wei ZHANG; Yi-kang HE; Rong ZENG

    2010-01-01

    This paper deals with an improved direct power control(DPC)strategy for the pulse width modulation(PWM)voltage source converter(VSC)under unbalanced grid voltage conditions.In order to provide enhanced control performance for the VSC,the resonant controllers tuned at the double grid frequency are applied in the DPC design to eliminate the power pulsations and dc link voltage ripples produced by the transient unbalanced grid faults.In this way,the output power and dc link voltage of the VSC can be directly regulated without positive and negative sequential decomposition.As a result,and as has been verified by experiment,the proposed method can provide fast dynamic response with easy implementation.

  5. 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.

  6. 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.

  7. 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.

  8. Design and Control of Disc PMSM Directly Driven Wheel for Tramcar

    Directory of Open Access Journals (Sweden)

    Zhenggang Lu

    2014-01-01

    Full Text Available A new solution of disc permanent magnet synchronous motor (PMSM directly driven wheel is proposed as a design customized for low floor tramcar. And the motors are overhung on the bogie frame to make the weight as the sprung mass. Meanwhile, the universal coupling is installed between the driven wheel and motor shaft. A disc PMSM is designed according to the demand of traction power. The motors are not only traction and steering actuators but are also regarded as sensors to obtain the rotational speed of motor directly driven wheel. Through the obtained data, an active sensorless steering control method is applied using the relative rotational speed between wheel pair. Finally, models combined with motor control and steering control are set up to check the control strategies. The simulation results indicate that sliding mode observer has the functionality of estimating the rotating speed with high accuracy for active steering control. The tramcar exhibits self-steering and better negotiation under active steering control. The tramcar is under a better condition of running along the central line of track with small attack angle and low power consumption while passing the shape curve track.

  9. Rigid Body Attitude Control Based on a Manifold Representation of Direction Cosine Matrices

    Science.gov (United States)

    Nakath, David; Clemens, Joachim; Rachuy, Carsten

    2017-01-01

    Autonomous systems typically actively observe certain aspects of their surroundings, which makes them dependent on a suitable controller. However, building an attitude controller for three degrees of freedom is a challenging task, mainly due to singularities in the different parametrizations of the three dimensional rotation group SO(3). Thus, we propose an attitude controller based on a manifold representation of direction cosine matrices: In state space, the attitude is globally and uniquely represented as a direction cosine matrix R ∈ SO(3). However, differences in the state space, i.e., the attitude errors, are exposed to the controller in the vector space ℝ3. This is achieved by an operator, which integrates the matrix logarithm mapping from SO(3) to so(3) and the map from so(3) to ℝ3. Based on this representation, we derive a proportional and derivative feedback controller, whose output has an upper bound to prevent actuator saturation. Additionally, the feedback is preprocessed by a particle filter to account for measurement and state transition noise. We evaluate our approach in a simulator in three different spacecraft maneuver scenarios: (i) stabilizing, (ii) rest-to-rest, and (iii) nadir-pointing. The controller exhibits stable behavior from initial attitudes near and far from the setpoint. Furthermore, it is able to stabilize a spacecraft and can be used for nadir-pointing maneuvers.

  10. Joint-space Lyapunov-based direct adaptive control of a kinematically redundant telerobot manipulator

    Science.gov (United States)

    Nguyen, Charles C.; Zhou, Zhen-Lei; Mosier, Gary E.

    1993-01-01

    This paper presents the design of a joint-space adaptive control scheme for controlling the slave arm motion of a dual-arm telerobot system developed at Goddard Space Flight Center (GSFC) to study telerobotic operations in space. Each slave arm of the dual-arm system is a kinematically redundant manipulator with seven degrees of freedom (DOF). Using the concept of model reference adaptive control (MRAC) and Liupunov direct method, we derive an adaptation algorithm that adjusts the PD controller gains of the control scheme. The development of the adaptive control scheme assumes that the slave arm motion is non-compliant and slowly varying. The implementation of the derived control scheme does not require the computation of manipulator dynamics which makes the control scheme sufficiently fast for real-time applications. Computer simulation study performed for the 7-DOF slave arm shows that the developed control scheme can efficiently adapt to sudden change in payload while tracking various test trajectories such as ramp or sinusoids with negligible position errors.

  11. Enhanced Cu-to-Cu direct bonding by controlling surface physical properties

    Science.gov (United States)

    Chiang, Po-Hao; Liang, Sin-Yong; Song, Jenn-Ming; Huang, Shang-Kun; Chiu, Ying-Ta; Hung, Chih-Pin

    2017-03-01

    Cu-to-Cu direct bonding is one of the key technologies for three-dimensional (3D) chip stacking. This research proposes a new concept to enhance Cu-to-Cu direct bonding through the control of surface physical properties. A linear relationship between bonding strength and the H/\\sqrt{R} value of the bonding face (H: subsurface hardness, R: surface roughness) was found. Low vacuum air plasma and thermal annealing were adopted to adjust the surface physical conditions. Instead of surface activation, an acceleration in copper atom diffusion due to plasma-induced compressive stress accounts for the improvement in bonding strength.

  12. Executive control of stimulus-driven and goal-directed attention in visual working memory.

    Science.gov (United States)

    Hu, Yanmei; Allen, Richard J; Baddeley, Alan D; Hitch, Graham J

    2016-10-01

    We examined the role of executive control in stimulus-driven and goal-directed attention in visual working memory using probed recall of a series of objects, a task that allows study of the dynamics of storage through analysis of serial position data. Experiment 1 examined whether executive control underlies goal-directed prioritization of certain items within the sequence. Instructing participants to prioritize either the first or final item resulted in improved recall for these items, and an increase in concurrent task difficulty reduced or abolished these gains, consistent with their dependence on executive control. Experiment 2 examined whether executive control is also involved in the disruption caused by a post-series visual distractor (suffix). A demanding concurrent task disrupted memory for all items except the most recent, whereas a suffix disrupted only the most recent items. There was no interaction when concurrent load and suffix were combined, suggesting that deploying selective attention to ignore the distractor did not draw upon executive resources. A final experiment replicated the independent interfering effects of suffix and concurrent load while ruling out possible artifacts. We discuss the results in terms of a domain-general episodic buffer in which information is retained in a transient, limited capacity privileged state, influenced by both stimulus-driven and goal-directed processes. The privileged state contains the most recent environmental input together with goal-relevant representations being actively maintained using executive resources.

  13. The State Financial Control in Ukraine: Directions of Improvement of its Organization and Evaluation

    Directory of Open Access Journals (Sweden)

    Lomeiko Yuliia A.

    2016-05-01

    Full Text Available The aim of the article is to examine the essence of the state financial control, identify directions of its improvement and define effective methods for its evaluation. On the basis of the results of analysis of modern scientific works it is determined that the precondition for building an effective state financial control system is defining its role in public financial relationships. According to the data of the conducted study it was concluded that first of all, the state financial control is an instrument of fiscal policy and, therefore, its direct purpose is ensuring a sustainable socio-economic development of the country, i.e., achieving the goal of the fiscal policy. Besides, there revealed the need to harmonize the components of the fiscal policy and types of the state financial control in order to build an effective institutional structure of public administration. It is proved that the division of the state financial control into internal and external must be conducted in accordance with the fact whether the controlling body and the subject under control belong to the same or different branch of power. Also the results of the study suggest that for Ukraine it is expedient to choose the model of a decentralized internal state financial control instead of the existing mixed one in order to avoid duplication by the State Audit Service of Ukraine bodies of partially the functions of the Audit Chamber, and partially those of internal control departments, which operate in the executive branch. There determined inappropriateness of building a system of state internal financial control on the basis of the principles provided for the bodies of the external state financial control. This situation leads to ungrounded definition of the internal control as an object of internal audit, which is carried out by structural units in budget organizations. It is also important to emphasize the need to evaluate managerial decisions in exercising the audit

  14. Direct Adaptive Control Methodologies for Flexible-Joint Space Manipulators with Uncertainties and Modeling Errors

    Science.gov (United States)

    Ulrich, Steve

    This work addresses the direct adaptive trajectory tracking control problem associated with lightweight space robotic manipulators that exhibit elastic vibrations in their joints, and which are subject to parametric uncertainties and modeling errors. Unlike existing adaptive control methodologies, the proposed flexible-joint control techniques do not require identification of unknown parameters, or mathematical models of the system to be controlled. The direct adaptive controllers developed in this work are based on the model reference adaptive control approach, and manage modeling errors and parametric uncertainties by time-varying the controller gains using new adaptation mechanisms, thereby reducing the errors between an ideal model and the actual robot system. More specifically, new decentralized adaptation mechanisms derived from the simple adaptive control technique and fuzzy logic control theory are considered in this work. Numerical simulations compare the performance of the adaptive controllers with a nonadaptive and a conventional model-based controller, in the context of 12.6 m xx 12.6 m square trajectory tracking. To validate the robustness of the controllers to modeling errors, a new dynamics formulation that includes several nonlinear effects usually neglected in flexible-joint dynamics models is proposed. Results obtained with the adaptive methodologies demonstrate an increased robustness to both uncertainties in joint stiffness coefficients and dynamics modeling errors, as well as highly improved tracking performance compared with the nonadaptive and model-based strategies. Finally, this work considers the partial state feedback problem related to flexible-joint space robotic manipulators equipped only with sensors that provide noisy measurements of motor positions and velocities. An extended Kalman filter-based estimation strategy is developed to estimate all state variables in real-time. The state estimation filter is combined with an adaptive

  15. 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......) with input and input-rate limits. The algorithm alternates between solving an extended LQCP and a highly structured quadratic program. These quadratic programs are solved using a Riccati iteration procedure, and a structure-exploiting interior-point method, respectively. The computational cost per iteration...... is quadratic in the dimensions of the controlled system, and linear in the length of the prediction horizon. Simulations show that the approach proposed in this paper is more than an order of magnitude faster than several state-of-the-art quadratic programming algorithms, and that the difference in computation...

  16. Direct Yaw Control of Vehicle using State Dependent Riccati Equation with Integral Terms

    Directory of Open Access Journals (Sweden)

    SANDHU, F.

    2016-05-01

    Full Text Available Direct yaw control of four-wheel vehicles using optimal controllers such as the linear quadratic regulator (LQR and the sliding mode controller (SMC either considers only certain parameters constant in the nonlinear equations of vehicle model or totally neglect their effects to obtain simplified models, resulting in loss of states for the system. In this paper, a modified state-dependent Ricatti equation method obtained by the simplification of the vehicle model is proposed. This method overcomes the problem of the lost states by including state integrals. The results of the proposed system are compared with the sliding mode slip controller and state-dependent Ricatti equation method using high fidelity vehicle model in the vehicle simulation software package, Carsim. Results show 38% reduction in the lateral velocity, 34% reduction in roll and 16% reduction in excessive yaw by only increasing the fuel consumption by 6.07%.

  17. Optimization of a neural architecture for the direct control of a Boost converter

    Directory of Open Access Journals (Sweden)

    Fredy Hernán Martinez Sarmiento

    2012-06-01

    Full Text Available In research related to control of DC/DC converters, artificial intelligence techniques are a great improvement in the design and performance. However, some of these tools require the use of trial and error strategies in the design, making it difficult to obtain an optimal structure. In this paper, we propose a direct control based on artificial neural network, whose design has been optimized using bio-inspired searching strategies, with the idea of optimizing simultaneously two different but important aspects of the network: architecture and weights connections. The control was successfully applied to a boost type converter. The results obtained allow us to observe the dynamic performance of the scheme, in which the response time and variation in the output voltage can be concluded that the criteria used for the control loop design were appropriate.

  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. Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide.

    Science.gov (United States)

    Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

    2013-12-18

    Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications.

  20. 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.

  1. Direct switching control of DC-DC power electronic converters using hybrid system theory

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.; Lin, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wang, C. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wayne State Univ., Detroit, MI (United States). Div. of Engineering Technology

    2010-07-01

    A direct switching control (DSC) scheme for power electronics converters was described. The system was designed for use in both traditional and renewable energy applications as well as in electric drive vehicles. The proposed control scheme was based on a detailed hybrid system converter model that used model predictive control (MPC), piecewise affine (PWA) approximations and constrained optimal control methods. A DC-DC converter was modelled as a hybrid machine. Switching among different modes of the DC-DC converter were modelled as discrete events controlled by the hybrid controller. The modelling scheme was applied to a Buck converter. The DSC was used to control the switch of the power converter based on a hybrid machine model. Results of the study showed that the method can be used to regulate output voltage and inductor currents. The method also provides fast transient responses and effectively regulates both currents and voltage. The controller can be used to provide immediate responses to dynamic disturbances and output voltage fluctuations. 23 refs., 7 figs.

  2. 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...... is used as the bids from the ACL customers, is utilized to determine the direct monetary compensation to the ACL customers. The proposed scheme was investigated for the PoolCo electricity market. The optimal DLC scheme is determined based on the minimum system operating cost which is comprised...... of the system energy cost, the system spinning reserve cost and the compensation cost to the ACL customers. Dynamic programming (DP) was used to obtain the optimal DLC scheme. The IEEE reliability test system (RTS) was studied to illustrate the proposed DLC scheme....

  3. Paxillin mediates sensing of physical cues and regulates directional cell motility by controlling lamellipodia positioning.

    Directory of Open Access Journals (Sweden)

    Julia E Sero

    Full Text Available Physical interactions between cells and the extracellular matrix (ECM guide directional migration by spatially controlling where cells form focal adhesions (FAs, which in turn regulate the extension of motile processes. Here we show that physical control of directional migration requires the FA scaffold protein paxillin. Using single-cell sized ECM islands to constrain cell shape, we found that fibroblasts cultured on square islands preferentially activated Rac and extended lamellipodia from corner, rather than side regions after 30 min stimulation with PDGF, but that cells lacking paxillin failed to restrict Rac activity to corners and formed small lamellipodia along their entire peripheries. This spatial preference was preceded by non-spatially constrained formation of both dorsal and lateral membrane ruffles from 5-10 min. Expression of paxillin N-terminal (paxN or C-terminal (paxC truncation mutants produced opposite, but complementary, effects on lamellipodia formation. Surprisingly, pax-/- and paxN cells also formed more circular dorsal ruffles (CDRs than pax+ cells, while paxC cells formed fewer CDRs and extended larger lamellipodia even in the absence of PDGF. In a two-dimensional (2D wound assay, pax-/- cells migrated at similar speeds to controls but lost directional persistence. Directional motility was rescued by expressing full-length paxillin or the N-terminus alone, but paxN cells migrated more slowly. In contrast, pax-/- and paxN cells exhibited increased migration in a three-dimensional (3D invasion assay, with paxN cells invading Matrigel even in the absence of PDGF. These studies indicate that paxillin integrates physical and chemical motility signals by spatially constraining where cells will form motile processes, and thereby regulates directional migration both in 2D and 3D. These findings also suggest that CDRs may correspond to invasive protrusions that drive cell migration through 3D extracellular matrices.

  4. Paxillin mediates sensing of physical cues and regulates directional cell motility by controlling lamellipodia positioning.

    Science.gov (United States)

    Sero, Julia E; Thodeti, Charles K; Mammoto, Akiko; Bakal, Chris; Thomas, Sheila; Ingber, Donald E

    2011-01-01

    Physical interactions between cells and the extracellular matrix (ECM) guide directional migration by spatially controlling where cells form focal adhesions (FAs), which in turn regulate the extension of motile processes. Here we show that physical control of directional migration requires the FA scaffold protein paxillin. Using single-cell sized ECM islands to constrain cell shape, we found that fibroblasts cultured on square islands preferentially activated Rac and extended lamellipodia from corner, rather than side regions after 30 min stimulation with PDGF, but that cells lacking paxillin failed to restrict Rac activity to corners and formed small lamellipodia along their entire peripheries. This spatial preference was preceded by non-spatially constrained formation of both dorsal and lateral membrane ruffles from 5-10 min. Expression of paxillin N-terminal (paxN) or C-terminal (paxC) truncation mutants produced opposite, but complementary, effects on lamellipodia formation. Surprisingly, pax-/- and paxN cells also formed more circular dorsal ruffles (CDRs) than pax+ cells, while paxC cells formed fewer CDRs and extended larger lamellipodia even in the absence of PDGF. In a two-dimensional (2D) wound assay, pax-/- cells migrated at similar speeds to controls but lost directional persistence. Directional motility was rescued by expressing full-length paxillin or the N-terminus alone, but paxN cells migrated more slowly. In contrast, pax-/- and paxN cells exhibited increased migration in a three-dimensional (3D) invasion assay, with paxN cells invading Matrigel even in the absence of PDGF. These studies indicate that paxillin integrates physical and chemical motility signals by spatially constraining where cells will form motile processes, and thereby regulates directional migration both in 2D and 3D. These findings also suggest that CDRs may correspond to invasive protrusions that drive cell migration through 3D extracellular matrices.

  5. Minimizing Segregation During the Controlled Directional Solidification of Dendritic Alloys Publication: Metallurgical and Materials Transactions

    Science.gov (United States)

    Grugel, R. N.; Fedoseyev, A. I.; Kim, S.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Gravity-driven thermosolutal convection that arises during controlled directional solidification (DS) of dendritic alloys promotes detrimental macro-segregation (e.g. freckles and steepling) in products such as turbine blades. Considerable time and effort has been spent to experimentally and theoretically investigate this phenomena; although our knowledge has advanced to the point where convection can be modeled and accurately compared to experimental results, little has been done to minimize its onset and deleterious effects. The experimental work demonstrates that segregation can be. minimized and microstructural uniformity promoted when a slow axial rotation is applied to the sample crucible during controlled directional solidification processing. Numerical modeling utilizing continuation and bifurcation methods have been employed to develop accurate physical and mathematical models with the intent of identifying and optimizing processing parameters.

  6. A dynamical programming approach for controlling the directed abelian Dhar-Ramaswamy model

    CERN Document Server

    Cajueiro, Daniel O

    2013-01-01

    A dynamical programming approach is used to deal with the problem of controlling the directed abelian Dhar-Ramaswamy model on two-dimensional square lattice. Two strategies are considered to obtain explicit results to this task. First, the optimal solution of the problem is characterized by the solution of the Bellman equation obtained by numerical algorithms. Second, the solution is used as a benchmark to value how far from the optimum other heuristics that can be applied to larger systems are. This approach is the first attempt on the direction of schemes for controlling self-organized criticality that are based on optimization principles that consider explicitly a tradeoff between the size of the avalanches and the cost of intervention.

  7. 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 differ......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......, power take-off driven implements with rotating weeding devices demonstrated similar control efficacies against a mixed stand composing C. arvense, Tussilago farfara, Elytrigia repens and Artemisia vulgaris. One pass was conducted a week after barley harvest followed by another pass 3 weeks later...... and 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Yan [School of Physic and Optoelectronic, Dalian University of Technology, Dalian 116024 (China)]. E-mail: xia-208@163.com; Song, He-Shan [School of Physic and Optoelectronic, Dalian University of Technology, Dalian 116024 (China)]. E-mail: hssong@dlut.edu.cn

    2007-04-23

    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.

  9. 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.

  10. Simulation study on the starting characteristics of a kind of improved direct torque control system

    Institute of Scientific and Technical Information of China (English)

    YE Jin-jiao; MENG Qing-chun; GUO Rui

    2004-01-01

    Analyzed working principle and starting process of asynchronous motor direct torque control system. In order to solve the problem of serious fluctuation of starting current in traditional control scheme, the author puts forward a new kind of starting method which can limit voltage value to achieve the goal of reducing fluctuation of the current by increasing zero voltage vectors during the stage of starting. The author has also carried on simulation study on the system, and the result of simulation study shows that this method is effectual.

  11. Combined indirect and direct method for adaptive fuzzy output feedback control of nonlinear system

    Institute of Scientific and Technical Information of China (English)

    Ding Quanxin; Chen Haitong; Jiang Changsheng; Chen Zongji

    2007-01-01

    A novel control method for a general class of nonlinear systems using fuzzy logic systems (FLSs) is presertted.Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.

  12. Advanced design of conductive polymeric arrays with controlled electrical resistance using direct laser interference patterning

    Energy Technology Data Exchange (ETDEWEB)

    Lasagni, A.F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Acevedo, D.F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany); Universidad Nacional de Rio Cuarto, Departamento de Quimica, Cordoba (Argentina); Barbero, C.A. [Universidad Nacional de Rio Cuarto, Departamento de Quimica, Cordoba (Argentina); Muecklich, F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany)

    2008-06-15

    In this work, we report a simple method for the fabrication of regular conducting polyaniline periodic arrays on large areas of glass or gold substrates using direct laser interference patterning. Additionally, by controlling the laser intensity it is possible to precisely tune the width of the periodic arrays and consequently the electrical resistance of the polyaniline strips. The periodic arrays were characterized using scanning electron microscopy, white light interferometry and cyclic voltametry. The great importance of the method reported lies both in its versatility and the ability to control the properties of the modified polymer electrodes with high precision. This is important for prospective applications such as electrochemical sensors. (orig.)

  13. Combining spanwise morphing, inline motion and model based optimization for force magnitude and direction control

    Science.gov (United States)

    Scheller, Johannes; Braza, Marianna; Triantafyllou, Michael

    2016-11-01

    Bats and other animals rapidly change their wingspan in order to control the aerodynamic forces. A NACA0013 type airfoil with dynamically changing span is proposed as a simple model to experimentally study these biomimetic morphing wings. Combining this large-scale morphing with inline motion allows to control both force magnitude and direction. Force measurements are conducted in order to analyze the impact of the 4 degree of freedom flapping motion on the flow. A blade-element theory augmented unsteady aerodynamic model is then used to derive optimal flapping trajectories.

  14. Flux observer algorithms for direct torque control of brushless doubly-fed reluctance machines

    OpenAIRE

    Chaal, Hamza; Jovanovic, Milutin

    2009-01-01

    Direct Torque Control (DTC) has been extensively researched and applied to most AC machines during the last two decades. Its first application to the Brushless Doubly-Fed Reluctance Machine (BDFRM), a promising cost-effective candidate for drive and generator systems with limited variable speed ranges (such as large pumps or wind turbines), has only been reported a few years ago. However, the original DTC scheme has experienced flux estimation problems and compromised performance under the ma...

  15. 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.

  16. Controllability and observability analysis for vertex domination centrality in directed networks.

    Science.gov (United States)

    Wang, Bingbo; Gao, Lin; Gao, Yong; Deng, Yue; Wang, Yu

    2014-06-23

    Topological centrality is a significant measure for characterising the relative importance of a node in a complex network. For directed networks that model dynamic processes, however, it is of more practical importance to quantify a vertex's ability to dominate (control or observe) the state of other vertices. In this paper, based on the determination of controllable and observable subspaces under the global minimum-cost condition, we introduce a novel direction-specific index, domination centrality, to assess the intervention capabilities of vertices in a directed network. Statistical studies demonstrate that the domination centrality is, to a great extent, encoded by the underlying network's degree distribution and that most network positions through which one can intervene in a system are vertices with high domination centrality rather than network hubs. To analyse the interaction and functional dependence between vertices when they are used to dominate a network, we define the domination similarity and detect significant functional modules in glossary and metabolic networks through clustering analysis. The experimental results provide strong evidence that our indices are effective and practical in accurately depicting the structure of directed networks.

  17. 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.

  18. Simulation platform for direct load control of household appliances. Literature survey and G2 implementation

    Energy Technology Data Exchange (ETDEWEB)

    Kolm, J.; Vlaheli, A.

    1996-10-01

    There is an incentive for the power utilities to look for other ways than building new power stations to satisfy increasing customer power needs. One way to fulfill this demand is by redistributing the available electric power between the different power consumers. This method can successfully be used during high peak hours. The utility is also able to make financial profits selling the redistributed electric power at a higher price to customers with temporary high power demands. Direct Load Control - DLC, a Demand Side Management - DSM tool, is one way to achieve a redistribution of electric power. This masters thesis project consisted in developing a user-friendly simulation platform for domestic appliances combined with an electric power control system to be employed for Direct Load Control. The platform contains the necessary facilities for designing an electrical distribution network model and is implemented in G2, an object-oriented real-time environment. The final application provides an on-line instrument for the utility to control the power consumption over the entire system in terms of dispensing power in an electrical network. The report consists of two main parts. The first part describes a literature survey we systematically compiled to gather literature sources. The second part outlines our design and implementation of the G2 simulation platform for a water-heater model with a Direct Load Control system. The entire simulation platform is designed to allow a flexible change and improvement of the different models. Consequently, our software is a powerful tool for studying a wide range of problems related to a Load Management program involving electrical household loads. 9 refs, 32 figs

  19. 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.

  20. Application of drive circuit based on L298N in direct current motor speed control system

    Science.gov (United States)

    Yin, Liuliu; Wang, Fang; Han, Sen; Li, Yuchen; Sun, Hao; Lu, Qingjie; Yang, Cheng; Wang, Quanzhao

    2016-10-01

    In the experiment of researching the nanometer laser interferometer, our design of laser interferometer circuit system is up to the wireless communication technique of the 802.15.4 IEEE standard, and we use the RF TI provided by Basic to receive the data on speed control system software. The system's hardware is connected with control module and the DC motor. However, in the experiment, we found that single chip microcomputer control module is very difficult to drive the DC motor directly. The reason is that the DC motor's starting and braking current is larger than the causing current of the single chip microcomputer control module. In order to solve this problem, we add a driving module that control board can transmit PWM wave signal through I/O port to drive the DC motor, the driving circuit board can come true the function of the DC motor's positive and reversal rotation and speed adjustment. In many various driving module, the L298N module's integrated level is higher compared with other driver module. The L298N model is easy to control, it not only can control the DC motor, but also achieve motor speed control by modulating PWM wave that the control panel output. It also has the over-current protection function, when the motor lock, the L298N model can protect circuit and motor. So we use the driver module based on L298N to drive the DC motor. It is concluded that the L298N driver circuit module plays a very important role in the process of driving the DC motor in the DC motor speed control system.

  1. Tuning of PID controllers for integrating systems using direct synthesis method.

    Science.gov (United States)

    Anil, Ch; Padma Sree, R

    2015-07-01

    A PID controller is designed for various forms of integrating systems with time delay using direct synthesis method. The method is based on comparing the characteristic equation of the integrating system and PID controller with a filter with the desired characteristic equation. The desired characteristic equation comprises of multiple poles which are placed at the same desired location. The tuning parameter is adjusted so as to achieve the desired robustness. Tuning rules in terms of process parameters are given for various forms of integrating systems. The tuning parameter can be selected for the desired robustness by specifying Ms value. The proposed controller design method is applied to various transfer function models and to the nonlinear model equations of jacketed CSTR to show its effectiveness and applicability.

  2. Dynamic modeling and direct power control of wind turbine driven DFIG under unbalanced network voltage conditions

    Institute of Scientific and Technical Information of China (English)

    Jia-bing HU; Yi-kang HE; Lie XU

    2008-01-01

    This paper proposes an analysis and a direct power control (DPC) design of a wind turbine driven doubly-fed in-duction generator (DFIG) under unbalanced network voltage conditions. A DFIG model described in the positive and negative synchronous reference frames is presented. Variations of the stator output active and reactive powers are fully deduced in the presence of negative sequence supply voltage and rotor flux. An enhanced DPC scheme is proposed to eliminate stator active power oscillation during network unbalance. The proposed control scheme removes rotor current regulators and the decomposition processing of positive and negative sequence rotor currents. Simulation results using PSCAD/EMTDC are presented on a 2-MW DFIG wind power generation system to validate the feasibility of the proposed control scheme under balanced and unbalanced network conditions.

  3. Asymptotic regulation of cascade systems with unknown control directions and nonlinear parameterization

    Institute of Scientific and Technical Information of China (English)

    Qiangde WANG; Chunling WEI; Yuqiang WU

    2009-01-01

    A robust partial-state feedback asymptotic regulating control scheme is developed for a class of cascade systems with both nonlinear uncertainties and unknown control directions.A parameter separation technique is introduced to separate the time-varying uncertainty and the unmeasurable state from nonlinear functions.Then,the Nussbaum-type gain method together with the idea of changing supply functions is adopted in the design of a smooth partial-state regulator that can ensure all the signals of the closed-loop system are globally uniformly bounded.Especially,the system state asymptotically converges to zero.The design procedure is illustrated through an example and the simulation results show that the controller is feasible and effective.

  4. Direct adaptive control for a class of MIMO nonlinear discrete-time systems

    Institute of Scientific and Technical Information of China (English)

    Lei Li; Zhizhong Mao

    2014-01-01

    This paper considers the problem of adaptive con-trol for a class of multiple input multiple output (MIMO) nonlinear discrete-time systems based on input-output model with unknown interconnections between subsystems. Based on the Taylor ex-pand technology, an equivalent model in affine-like form is derived for the original nonaffine nonlinear system. Then a direct adap-tive neural network (NN) control er is implemented based on the affine-like model. By finding an orthogonal matrix to tune the NN weights, the closed-loop system is proven to be semiglobal y uni-formly ultimately bounded. The σ-modification technique is used to remove the requirement of persistence excitation during the adaptation. The control performance of the closed-loop system is guaranteed by suitably choosing the design parameters.

  5. Very low speed performance of active flux based sensorless control: interior permanent magnet synchronous motor vector control versus direct torque and flux control

    DEFF Research Database (Denmark)

    Paicu, M. C.; Boldea, I.; Andreescu, G. D.

    2009-01-01

    This study is focused on very low speed performance comparison between two sensorless control systems based on the novel ‘active flux' concept, that is, the current/voltage vector control versus direct torque and flux control (DTFC) for interior permanent magnet synchronous motor (IPMSM) drives...... with space vector modulation (SVM), without signal injection. The active flux, defined as the flux that multiplies iq current in the dq-model torque expression of all ac machines, is easily obtained from the stator-flux vector and has the rotor position orientation. Therefore notable simplification...

  6. 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.

  7. 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.

  8. Remote screening and direct control of the bacterial infection of gardens

    Science.gov (United States)

    Starodub, Nickolaj F.; Shavanova, Kateryna E.; Son'ko, Roman V.

    2014-10-01

    In last time gardens are often at the dangerous of viruses and bacteria infections. To preserve not only the coming harvest, but, in generally, to provide stability and growing horticultures the development of new generation of the analytical techniques for remote express screening vegetative state arrays and direct control of the appropriate infection if appearance of its maybe expected on the basis of previous surveys are very actually and important. For continuous monitoring we propose the application of the complex of the optical analytical devices as "Floratest" and "Plasmatest" (both produced in Ukraine) which is able to control step by step general situation with vegetable state and verify concrete situation with infection. General screening is accomplished on the control of the intensity of chlorophyll induction (IChF), namely, registration of so called Kautsky curve which testifies about physiological mechanisms of energy generation, accumulation and effective ways of its realization in cells. The measuring may be done by direct way on the number of individual vegetables and remote screening of massive with transferring registered signal direct in the laboratory. Next step of control connected with the application of the surface plasmon resonance (SPR) based immune biosensor which is able to determine concrete bacteria (for example, Erwinia amilovora) with the limit detection about 0.2 μg/ml, the overall time of the analysis within 30 min (5 min of the duration of one measurement). The traditional ELISA-method showed the sensitivity to this pathogen about 0.5 μg/ml, overall time of the analysis several hours and obligatory using additional expensive reagents.

  9. Control of roll and pitch motion during multi-directional balance perturbations.

    Science.gov (United States)

    Küng, Ursula Margareta; Horlings, C G C; Honegger, F; Duysens, J E J; Allum, J H J

    2009-04-01

    Does the central nervous system (CNS) independently control roll and pitch movements of the human body during balance corrections? To help provide an answer to this question, we perturbed the balance of 16 young healthy subjects using multi-directional rotations of the support surface. All rotations had pitch and roll components, for which either the roll (DR) or the pitch (DP) component were delayed by 150 ms or not at all (ND). The outcome measures were the biomechanical responses of the body and surface EMG activity of several muscles. Across all perturbation directions, DR caused equally delayed shifts (150 ms) in peak lateral centre of mass (COM) velocity. Across directions, DP did not cause equally delayed shifts in anterior-posterior COM velocity. After 300 ms however, the vector direction of COM velocity was similar to the ND directions. Trunk, arm and knee joint rotations followed this roll compared to pitch pattern, but were different from ND rotation synergies after 300 ms, suggesting an intersegmental compensation for the delay effects. Balance correcting responses of muscles demonstrated both roll and pitch directed components regardless of axial alignment. We categorised muscles into three groups: pitch oriented, roll oriented and mixed based on their responses to DR and DP. Lower leg muscles were pitch oriented, trunk muscles were roll oriented, and knee and arm muscles were mixed. The results of this study suggest that roll, but not pitch components, of balance correcting movement strategies and muscle synergies are separately programmed by the CNS. Reliance on differentially activated arm and knee muscles to correct roll perturbations reveals a dependence of the pitch response on that of roll, possibly due to biomechanical constraints, and accounts for the failure of DP to be transmitted equally in time across all limbs segments. Thus it appears the CNS preferentially programs the roll response of the body and then adjusts the pitch response

  10. SUMOylation at K707 of DGCR8 controls direct function of primary microRNA

    Science.gov (United States)

    Zhu, Changhong; Chen, Cheng; Huang, Jian; Zhang, Hailong; Zhao, Xian; Deng, Rong; Dou, Jinzhuo; Jin, Hui; Chen, Ran; Xu, Ming; Chen, Qin; Wang, Yanli; Yu, Jianxiu

    2015-01-01

    DGCR8 (DiGeorge syndrome critical region gene 8) is essential for primary microRNA (pri-miRNA) processing in the cell nucleus. It specifically combines with Drosha, a nuclear RNase III enzyme, to form the Microprocessor complex (MC) that cleaves pri-miRNA to precursor miRNA (pre-miRNA), which is further processed to mature miRNA by Dicer, a cytoplasmic RNase III enzyme. Increasing evidences suggest that pri-/pre-miRNAs have direct functions in regulation of gene expression, however the underlying mechanism how it is fine-tuned remains unclear. Here we find that DGCR8 is modified by SUMO1 at the major site K707, which can be promoted by its ERK-activated phosphorylation. SUMOylation of DGCR8 enhances the protein stability by preventing the degradation via the ubiquitin proteasome pathway. More importantly, SUMOylation of DGCR8 does not alter its association with Drosha, the MC activity and miRNA biogenesis, but rather influences its affinity with pri-miRNAs. This altered affinity of DGCR8 with pri-miRNAs seems to control the direct functions of pri-miRNAs in recognition and repression of the target mRNAs, which is evidently linked to the DGCR8 function in regulation of tumorigenesis and cell migration. Collectively, our data suggest a novel mechanism that SUMOylation of DGCR8 controls direct functions of pri-miRNAs in gene silencing. PMID:26202964

  11. 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

  12. Control of directed cell migration in vivo by membrane-to-cortex attachment.

    Directory of Open Access Journals (Sweden)

    Alba Diz-Muñoz

    Full Text Available Cell shape and motility are primarily controlled by cellular mechanics. The attachment of the plasma membrane to the underlying actomyosin cortex has been proposed to be important for cellular processes involving membrane deformation. However, little is known about the actual function of membrane-to-cortex attachment (MCA in cell protrusion formation and migration, in particular in the context of the developing embryo. Here, we use a multidisciplinary approach to study MCA in zebrafish mesoderm and endoderm (mesendoderm germ layer progenitor cells, which migrate using a combination of different protrusion types, namely, lamellipodia, filopodia, and blebs, during zebrafish gastrulation. By interfering with the activity of molecules linking the cortex to the membrane and measuring resulting changes in MCA by atomic force microscopy, we show that reducing MCA in mesendoderm progenitors increases the proportion of cellular blebs and reduces the directionality of cell migration. We propose that MCA is a key parameter controlling the relative proportions of different cell protrusion types in mesendoderm progenitors, and thus is key in controlling directed migration during gastrulation.

  13. Control of directed cell migration in vivo by membrane-to-cortex attachment.

    Science.gov (United States)

    Diz-Muñoz, Alba; Krieg, Michael; Bergert, Martin; Ibarlucea-Benitez, Itziar; Muller, Daniel J; Paluch, Ewa; Heisenberg, Carl-Philipp

    2010-11-30

    Cell shape and motility are primarily controlled by cellular mechanics. The attachment of the plasma membrane to the underlying actomyosin cortex has been proposed to be important for cellular processes involving membrane deformation. However, little is known about the actual function of membrane-to-cortex attachment (MCA) in cell protrusion formation and migration, in particular in the context of the developing embryo. Here, we use a multidisciplinary approach to study MCA in zebrafish mesoderm and endoderm (mesendoderm) germ layer progenitor cells, which migrate using a combination of different protrusion types, namely, lamellipodia, filopodia, and blebs, during zebrafish gastrulation. By interfering with the activity of molecules linking the cortex to the membrane and measuring resulting changes in MCA by atomic force microscopy, we show that reducing MCA in mesendoderm progenitors increases the proportion of cellular blebs and reduces the directionality of cell migration. We propose that MCA is a key parameter controlling the relative proportions of different cell protrusion types in mesendoderm progenitors, and thus is key in controlling directed migration during gastrulation.

  14. Sensorless Direct Power Control of Induction Motor Drive Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Abolfazl Halvaei Niasar

    2015-01-01

    Full Text Available This paper proposes the design of sensorless induction motor drive based on direct power control (DPC technique. It is shown that DPC technique enjoys all advantages of pervious methods such as fast dynamic and ease of implementation, without having their problems. To reduce the cost of drive and enhance the reliability, an effective sensorless strategy based on artificial neural network (ANN is developed to estimate rotor’s position and speed of induction motor. Developed sensorless scheme is a new model reference adaptive system (MRAS speed observer for direct power control induction motor drives. The proposed MRAS speed observer uses the current model as an adaptive model. The neural network has been then designed and trained online by employing a back propagation network (BPN algorithm. The estimator was designed and simulated in Simulink. Some simulations are carried out for the closed-loop speed control systems under various load conditions to verify the proposed methods. Simulation results confirm the performance of ANN based sensorless DPC induction motor drive in various conditions.

  15. Controlling Directionality and Dimensionality of Radiation by Perturbing Separable Bound States in the Continuum

    Science.gov (United States)

    Rivera, Nicholas; Hsu, Chia Wei; Zhen, Bo; Buljan, Hrvoje; Joannopoulos, John D.; Soljačić, Marin

    2016-09-01

    A bound state in the continuum (BIC) is an unusual localized state that is embedded in a continuum of extended states. Here, we present the general condition for BICs to arise from wave equation separability. Then we show that by exploiting perturbations of certain symmetry such BICs can be turned into resonances that radiate with a tailorable directionality and dimensionality. Using this general framework, we construct new examples of separable BICs and resonances that can exist in optical potentials for ultracold atoms, photonic systems, and systems described by tight binding. Such resonances with easily reconfigurable radiation allow for applications such as the storage and release of waves at a controllable rate and direction, as well systems that switch between different dimensions of confinement.

  16. 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.

  17. 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.

  18. Cancellation control law for lateral-directional dynamics of a supermaneuverable aircraft

    Science.gov (United States)

    Snell, Antony

    1993-01-01

    Cancellation control laws are designed which reduce the high levels of lateral acceleration encountered during aggressive rolling maneuvers executed at high angle of attack. Two independent problem are examined. One is to reduce lateral acceleration at the mass center, while the other focuses on lateral acceleration at the pilot's station, located 7.0 m forward of the mass center. Both of these problems are challenging and somewhat different in their limitations. In each case the design is based on a linearization of the lateral-directional dynamics about a high angle of attack condition. The controllers incorporate dynamic inversion inner loops to provide control of stability-axis roll- and yaw-rates and then employ cancellation filters in both feed-forward and feed-back signal paths. The relative simplicity of the control laws should allow nonlinear generalizations to be devised. Although it is shown that lateral acceleration can be reduced substantially by such control laws, this is at the cost of slowed roll response, poor dutch-roll damping or a combination of the two.

  19. Sliding mode direct power control of RSC for DFIGs driven by variable speed wind turbines

    Directory of Open Access Journals (Sweden)

    E.G. Shehata

    2015-12-01

    Full Text Available In spite of its several advantages, a classic direct power control (DPC of doubly fed induction generators (DFIGs driven by variable speed wind turbines has some drawbacks. In this paper, a simple and robust total sliding mode controller (TSMC is designed to improve the classical DPC performance without complicating the overall scheme. The TSMC is designed to regulate the DFIG stator active and reactive powers. Two integral switching functions are selected for describing the switching surfaces of the active and reactive powers. Reaching phase stability problem of the classical sliding mode controller is avoided in the proposed TSMC. Neither current control loops nor accurate values of machine parameters are required in the proposed scheme. In addition, axes transformation of the stator voltage and current are eliminated. The grid side converter is controlled based on DPC principle to regulate both DC-link voltage and total reactive power. The feasibility of the proposed DPC scheme is validated through simulation studies on a 1.5 MW wind power generation system. The performance of the proposed and conventional DPC schemes is compared under different operating conditions.

  20. Direct Control of Spin Distribution and Anisotropy in Cu-Dithiolene Complex Anions by Light

    Directory of Open Access Journals (Sweden)

    Hiroki Noma

    2016-03-01

    Full Text Available Electrical and magnetic properties are dominated by the (delocalization and the anisotropy in the distribution of unpaired electrons in solids. In molecular materials, these properties have been indirectly controlled through crystal structures using various chemical modifications to affect molecular structures and arrangements. In the molecular crystals, since the energy band structures can be semi-quantitatively known using band calculations and solid state spectra, one can anticipate the (delocalization of unpaired electrons in particular bands/levels, as well as interactions with other electrons. Thus, direct control of anisotropy and localization of unpaired electrons by locating them in selected energy bands/levels would realize more efficient control of electrical and magnetic properties. In this work, it has been found that the unpaired electrons on Cu(II-complex anions can be optically controlled to behave as anisotropically-delocalized electrons (under dark or isotropically-localized electrons like free electrons (under UV, the latter of which has hardly been observed in the ground states of Cu(II-complexes by any chemical modifications. Although the compounds examined in this work did not switch between conductors and magnets, these findings indicate that optical excitation in the [Cu(dmit2]2− salts should be an effective method to control spin distribution and anisotropy.

  1. Electronic Nature of Ketone Directing Group as a Key To Control C-2 vs C-4 Alkenylation of Indoles.

    Science.gov (United States)

    Lanke, Veeranjaneyulu; Bettadapur, Kiran R; Prabhu, Kandikere Ramaiah

    2016-11-04

    A novel mode of achieving site selectivity between C-2 and C-4 positions in the indole framework by altering the property of the ketone directing group is disclosed. Methyl ketone, as directing group, furnishes exclusively C-2 alkenylated product, whereas trifluoromethyl ketone changes the selectivity to C-4, indicating that the electronic nature of the directing group controls the unusual choice between a 5-membered and a 6-membered metallacycle. The screening of other carbonyl-derived directing groups reveals that strong and weak directing groups exhibit opposite selectivity. Experimental controls and deuteration experiments lend support to the proposed mechanism.

  2. 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.

  3. 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

  4. 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.

  5. 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...... stable region (the real part of eigenvalue is equal to zero). The vector-based DPC combines with a space vector modulation technique to achieve a constant switching frequency. The simulation and experimental results clearly validate the effectiveness and feasibility of the proposed vector-based DPC...

  6. Experimental System Identification and Black Box Modeling of Hydraulic Directional Control Valve

    Directory of Open Access Journals (Sweden)

    Sondre Sanden Tørdal

    2015-10-01

    Full Text Available Directional control valves play a large role in most hydraulic systems. When modeling the hydraulic systems, it is important that both the steady state and dynamic characteristics of the valves are modeled correctly to reproduce the dynamic characteristics of the entire system. In this paper, a proportional valve (Brevini HPV 41 is investigated to identify its dynamic and steady state characteristics. The steady state characteristics are identified by experimental flow curves. The dynamics are determined through frequency response analysis and identified using several transfer functions. The paper also presents a simulation model of the valve describing both steady state and dynamic characteristics. The simulation results are verified through several experiments.

  7. Increasing Fuel Efficiency of Direct Methanol Fuel Cell Systems with Feedforward Control of the Operating Concentration

    Directory of Open Access Journals (Sweden)

    Youngseung Na

    2015-09-01

    Full Text Available 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 modification of it with a separate tank to recover condensed water. The set point for methanol concentration control in the solution is determined by fuel efficiency and varies with the current and other process variables. Feedforward concentration control enables variable concentration for dynamic loads. Simulation results were validated experimentally with fuel cell systems.

  8. Effect of Processing Pressure on Isolated Pore Formation during Controlled Directional Solidification in Small Channels

    Science.gov (United States)

    Cox, Matthew C.; Anilkumar, Amrutur V.; Grugel, RIchard N.; Lee, Chun P.

    2008-01-01

    Directional solidification experiments were performed, using succinonitrile saturated with nitrogen gas, to examine the effects of in-situ processing pressure changes on the formation growth, and evolution of an isolated, cylindrical gaseous pore. A novel solidification facility, capable of processing thin cylindrical samples (I.D. < 1.0 mm), under controlled pressure conditions, was used for the experiments. A new experimental method for growing the isolated pore from a seed bubble is introduced. The experimental results indicate that an in-situ processing pressure change will result in either a transient change in pore diameter or a complete termination of pore growth, indicating that pressure changes can be used as a control parameter to terminate bubble growth. A simple analytical model has been introduced to explain the experimental observations.

  9. 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

  10. Direct coupling: a possible strategy to control fruit production in alternate bearing

    Science.gov (United States)

    Prasad, Awadhesh; Sakai, Kenshi; Hoshino, Yoshinobu

    2017-01-01

    We investigated the theoretical possibility of applying phenomenon of synchronization of coupled nonlinear oscillators to control alternate bearing in citrus. The alternate bearing of fruit crops is a phenomenon in which a year of heavy yield is followed by an extremely light one. This phenomenon has been modeled previously by the resource budget model, which describes a typical nonlinear oscillator of the tent map type. We have demonstrated how direct coupling, which could be practically realized through grafting, contributes to the nonlinear dynamics of alternate bearing, especially phase synchronization. Our results show enhancement of out-of-phase synchronization in production, which depends on initial conditions obtained under the given system parameters. Based on these numerical experiments, we propose a new method to control alternate bearing, say in citrus, thereby enabling stable fruit production. The feasibility of validating the current results through field experimentation is also discussed. PMID:28051141

  11. Direct coupling: a possible strategy to control fruit production in alternate bearing

    Science.gov (United States)

    Prasad, Awadhesh; Sakai, Kenshi; Hoshino, Yoshinobu

    2017-01-01

    We investigated the theoretical possibility of applying phenomenon of synchronization of coupled nonlinear oscillators to control alternate bearing in citrus. The alternate bearing of fruit crops is a phenomenon in which a year of heavy yield is followed by an extremely light one. This phenomenon has been modeled previously by the resource budget model, which describes a typical nonlinear oscillator of the tent map type. We have demonstrated how direct coupling, which could be practically realized through grafting, contributes to the nonlinear dynamics of alternate bearing, especially phase synchronization. Our results show enhancement of out-of-phase synchronization in production, which depends on initial conditions obtained under the given system parameters. Based on these numerical experiments, we propose a new method to control alternate bearing, say in citrus, thereby enabling stable fruit production. The feasibility of validating the current results through field experimentation is also discussed.

  12. 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.

  13. Transcranial direct current stimulation in post-stroke dysphagia: a systematic review of randomized controlled trials

    Directory of Open Access Journals (Sweden)

    Kavian Ghandehari

    2016-07-01

    Full Text Available Introduction: The aim of this research was to systematically review all the randomized controlled trials that have evaluated the effect of transcranial direct current stimulation (tDCS on post-stroke dysphagia. Methods: Three electronic databases were searched for relevant articles that were uploaded from their inception to March 2015: PubMed, Cochrane Library (Cochrane Central Register of Controlled Trials, and Scopus. All data was that was related to the location of the cerebrovascular accident (CVA, the parameters of tDCS, post-stroke time to commencement of tDCS, the stimulated hemisphere, stimulation dose, any outcome measurements, and follow-up duration were extracted and assessed. Finally, a number of observations were generated through a qualitative synthesis of the extracted data.Result: Three eligible randomized controlled trials were included in the systematic review. All three trials reported that, in comparison to a placebo, tDCS had a statistically significant effect on post-stroke dysphagia.Discussion: The results of our systematic review suggest that tDCS may represent a promising novel treatment for post-stroke dysphagia. However, to date, little is known about the optimal parameters of tDCS for relieving post-stroke dysphagia. Further studies are warranted to refine this promising intervention by exploring the optimal parameters of tDCS.Conclusion: Since brainstem swallowing centers have bilateral cortical innervations, measures that enhance cortical input and sensorimotor control of brainstem swallowing may facilitate recovery from dysphagia.

  14. Active Speed Compensation Method of Direct Torque Control System and Stability Analysis

    Directory of Open Access Journals (Sweden)

    Rui Li

    2015-02-01

    Full Text Available By analyzing characteristics of the DTC (direct torque control system in electrical driving system, a shortcoming of the classical DTC method is to point out that it is unable to decouple the mutual interference between torque and speed, so that when a running asynchronous motor subjected to an instantaneous impact load, rotor speed and its deviation appears excessive fluctuations that can not be quickly restored to the initial set value. In this research, under conditions that without sensors for measuring load torque and rotor speed, to an electrical drive systems contains DTC devices, a novel ASCC (active speed compensation control method is proposed based on ADRC (active disturbance rejection control theory, on account of DTC model of asynchronous motor, a multiobjective observer is designed to regulate both the speed and the torque, and a proof of asymptotic stability that related this new control systems with the observer is made by theoretical deduction. Finally stimulating results show that this method can overcome the shortcomings of classical DTC system and greatly enhance the ability of the high-speed driving system to deal with unexpected impact loads.

  15. 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.

  16. Controllable synthesis of metal particles by a direct current electrochemical approach

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Shapes of copper and silver particles were successfully controlled by using a very simple,effective direct-current electrochemical approach without introducing any additives or templates. A diverse range of shapes and also different inner structures were thus accessible. The products prepared at relatively high potentials have flowerlike morphologies and exhibit flakes as building blocks. The uniformly thick flakes intersect mutually,have smooth surfaces and outwardly wavy edges. The particle diameter and the flake density can be easily controlled by changing potential and/or deposition time. With a decrease of potential,the particles’ shapes changed from flower to bud,to sphere and to octahedron. Surface plasmon resonance (SPR) properties of the supported metal particles were investigated by UV-Vis diffuse reflectance spectra (UV-Vis DRS) and surface enhanced Raman scattering (SERS). It was found that the copper octahedra exhibited three characteristic bands,and SERS effect increases with the number of flakes within individual particles. Based on the experimental results,the mechanism for direct-current electrochemical growth of metal nanostructures was discussed.

  17. Loss of lateral prefrontal cortex control in food-directed attention and goal-directed food choice in obesity

    NARCIS (Netherlands)

    Janssen, Lieneke K.; Duif, Iris; Loon, van Ilke; Wegman, Joost; Vries, de Jeanne H.M.; Cools, Roshan; Aarts, Esther

    2017-01-01

    Loss of lateral prefrontal cortex (lPFC)-mediated attentional control may explain the automatic tendency to eat in the face of food. Here, we investigate the neurocognitive mechanism underlying attentional bias to food words and its association with obesity using a food Stroop task. We tested 76 hea

  18. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Anthony B [Thermal Therapy Research Group, UCSF Radiation Oncology, San Francisco, CA (United States); Diederich, Chris J [Thermal Therapy Research Group, UCSF Radiation Oncology, San Francisco, CA (United States); Nau, William H [Thermal Therapy Research Group, UCSF Radiation Oncology, San Francisco, CA (United States); Gill, Harcharan [Department of Urology, Stanford University, Stanford, CA (United States); Bouley, Donna M [Department of Comparative Medicine, Stanford University, Stanford, CA (United States); Daniel, Bruce [Department of Radiology, Stanford University, Stanford, CA (United States); Rieke, Viola [Department of Radiology, Stanford University, Stanford, CA (United States); Butts, R Kim [Department of Radiology, Stanford University, Stanford, CA (United States); Sommer, Graham [Department of Radiology, Stanford University, Stanford, CA (United States)

    2004-01-21

    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, {approx}8 MHz) generated thermal lesions of {approx}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.

  20. Can transcranial direct current stimulation enhance performance of myoelectric control for multifunctional prosthesis?

    Science.gov (United States)

    Pan, Lizhi; Zhang, Dingguo; Duan, Renquan; Zhu, Xiangyang

    2014-01-01

    Pattern recognition based myoelectric control has been studied by many researchers. However, the classification accuracy was pretty low for amputees towards multifunctional prosthesis control in practice. In this work, a novel method of transcranial direct current stimulation (tDCS) which can modulate brain activity was used to enhance performance for myoelectric prosthesis control. The pilot study was conducted on three able-bodied subjects and one transradial amputee. Surface electromyography (EMG) signals were acquired from both arms when performing eleven hand and wrist motions in pre-tDCS and post-tDCS sessions. Time domain (TD) features and linear discriminant analysis (LDA) classifier were adopted to process EMG. For the non-dominant hand of the healthy subjects, active anodal tDCS of the contralateral primary motor cortex was able to significantly improve average classification accuracy by 3.82% (p 0.05). For amputated (phantom) hand of the amputee, active anodal tDCS was able to significantly improve average classification accuracy by 12.56%, while sham tDCS could not have such effect. For the dominant hand and intact hand, the average classification accuracies were stable and not significantly improved using either active tDCS or sham tDCS. The results show that tDCS is a powerful noninvasive method to modulate brain function and enhance EMG classification performance especially for the amputated hand towards multifunctional prosthesis control. The method proposed has a huge potential to promote EMG pattern recognition based control scheme to clinical application.

  1. Power system security enhancement through direct non-disruptive load control

    Science.gov (United States)

    Ramanathan, Badri Narayanan

    The transition to a competitive market structure raises significant concerns regarding reliability of the power grid. A need to build tools for security assessment that produce operating limit boundaries for both static and dynamic contingencies is recognized. Besides, an increase in overall uncertainty in operating conditions makes corrective actions at times ineffective leaving the system vulnerable to instability. The tools that are in place for stability enhancement are mostly corrective and suffer from lack of robustness to operating condition changes. They often pose serious coordination challenges. With deregulation, there have also been ownership and responsibility issues associated with stability controls. However, the changing utility business model and the developments in enabling technologies such as two-way communication, metering, and control open up several new possibilities for power system security enhancement. This research proposes preventive modulation of selected loads through direct control for power system security enhancement. Two main contributions of this research are the following: development of an analysis framework and two conceptually different analysis approaches for load modulation to enhance oscillatory stability, and the development and study of algorithms for real-time modulation of thermostatic loads. The underlying analysis framework is based on the Structured Singular Value (SSV or mu) theory. Based on the above framework, two fundamentally different approaches towards analysis of the amount of load modulation for desired stability performance have been developed. Both the approaches have been tested on two different test systems: CIGRE Nordic test system and an equivalent of the Western Electric Coordinating Council test system. This research also develops algorithms for real-time modulation of thermostatic loads that use the results of the analysis. In line with some recent load management programs executed by utilities, two

  2. Application of neural networks for permanent magnet synchronous motor direct torque control

    Institute of Scientific and Technical Information of China (English)

    Zhang Chunmei; Liu Heping; Chen Shujin; Wang Fangjun

    2008-01-01

    Neural networks 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. The application of neural networks to control interior permanent magnet synchronous motor using direct torque control (DTC) is discussed. A neural network is used to emulate the state selector of the DTC. The neural networks used are the back-propagation and radial basis function. To reduce the training patterns and increase the execution speed of the training process, the inputs of switching table are converted to digital signals, i.e., one bit represent the flux error, one bit the torque error, and three bits the region of stator flux. Computer simulations of the motor and neural-network system using the two approaches are presented and compared. Discussions about the back-propagation and radial basis function as the most promising training techniques are presented, giving its advantages and disadvantages. The system using back-propagation and radial basis function networks controller has quick parallel speed and high torque response.

  3. Evaluation of Direct Collocation Optimal Control Problem Formulations for Solving the Muscle Redundancy Problem.

    Science.gov (United States)

    De Groote, Friedl; Kinney, Allison L; Rao, Anil V; Fregly, Benjamin J

    2016-10-01

    Estimation of muscle forces during motion involves solving an indeterminate problem (more unknown muscle forces than joint moment constraints), frequently via optimization methods. When the dynamics of muscle activation and contraction are modeled for consistency with muscle physiology, the resulting optimization problem is dynamic and challenging to solve. This study sought to identify a robust and computationally efficient formulation for solving these dynamic optimization problems using direct collocation optimal control methods. Four problem formulations were investigated for walking based on both a two and three dimensional model. Formulations differed in the use of either an explicit or implicit representation of contraction dynamics with either muscle length or tendon force as a state variable. The implicit representations introduced additional controls defined as the time derivatives of the states, allowing the nonlinear equations describing contraction dynamics to be imposed as algebraic path constraints, simplifying their evaluation. Problem formulation affected computational speed and robustness to the initial guess. The formulation that used explicit contraction dynamics with muscle length as a state failed to converge in most cases. In contrast, the two formulations that used implicit contraction dynamics converged to an optimal solution in all cases for all initial guesses, with tendon force as a state generally being the fastest. Future work should focus on comparing the present approach to other approaches for computing muscle forces. The present approach lacks some of the major limitations of established methods such as static optimization and computed muscle control while remaining computationally efficient.

  4. Novel torque ripple minimization algorithm for direct torque control of induction motor drive

    Institute of Scientific and Technical Information of China (English)

    LONG Bo; GUO Gui-fang; HAO Xiao-hong; LI Xiao-ning

    2009-01-01

    To elucidate the principles of notable torque and flux ripple during the steady state of the conventional direct torque control (DTC) of induction machines, the factors of influence torque variation are examined. A new torque ripple minimization algorithm is proposed. The novel method eradicated the torque ripple by imposing the required stator voltage vector in each control cycle. The M and T axial components of the stator voltage are accomplished by measuring the stator flux error and the expected incremental value of the torque at every sampling time. The maximum angle rotation allowed is obtained. Experimental results showed that the proposed method combined with the space vector pulse width modulation(SVPWM) could be implemented in most existing digital drive controllers, offering high performance in both steady and transient states of the induction drives at full speed range. The result of the present work imphes that torque fluctuation could be eliminated by imposing proper stator voltage, and the proposed scheme could not only maintain constant switching frequency for the inverter, but also solve the heating problem and current harmonics in traditional induction motor drives.

  5. Modified deformable mirror stroke minimization control for direct imaging of exoplanets

    Science.gov (United States)

    Sun, He; Eldorado Riggs, A. J.; Kasdin, N. Jeremy; Vanderbei, Robert; Groff, Tyler

    2016-08-01

    For direct imaging of faint exoplanets, coronagraphs are widely used to suppress light and achieve a high contrast. Wavefront correction algorithms based on adaptive optics are introduced simultaneously to mitigate aberrations in the optical system. Stroke minimization is one of the primary control algorithms used for high-contrast wavefront control. This technique calculates the minimum deformation across the deformable mirrors' surface under the constraint that a targeted average contrast level in the search areas, namely the dark holes, is achieved. In this paper we present a modified linear constraint stroke minimization algorithm. Instead of using a single constraint on intensity averaged over all pixels, we constrain the electric field's real and imaginary part of each pixel in the dark holes. The new control algorithm can be written into a linear programming problem. Model reduction methods, including pixel binning and singular value decomposition (SVD), are further employed to avoid over-constraining the problem and to speed up computation. In numerical simulation, we find that the revised algorithm leads to more uniform dark holes and faster convergence.

  6. The effectiveness of the Family Health Strategy and the Directly Observed Treatment in controlling Tuberculosis

    Directory of Open Access Journals (Sweden)

    Sueli Santiago Baldan

    2016-10-01

    Full Text Available Backgrounds and objective: Strengthening Primary Health Care, making it the protagonist in the care of the person with tuberculosis, favors the identification of respiratory symptoms, as well as the diagnosis and early treatment, reducing the transmission of the disease and promoting adherence to treatment. This study aimed to investigate the effectiveness of the coverage of the Family Health Strategy- FSH and the Directly Observed Treatment Strategy – DOTS in control of non adherence to tuberculosis treatment. Methods: Exploratory study, based on secondary data. The investigated variables were: TB incidence rate (CI-TB, percentage of coverage by the FHS, treatment dropout rate and percentage of supply of DOTSin Mato Grosso do Sul. It was used the hierarchical cluster analysis method to look for patterns contained in the data set. Results: The data indicate that there are groups of municipalities in which the coverage by FHS and DOTS contributes to treatment adherence and control of the number of TB cases, while for other municipalities these measures have not been effective in reducing CI-TB and abandon to the treatment. The disease is distributed heterogeneously in the state. Conclusion: Professionals and health managers need to know the tuberculosis standards in their regions prioritizing and planning actions that contribute to an effective control of disease, transmission and greater adherence to treatment in their community.

  7. Controllability analysis of the directed human protein interaction network identifies disease genes and drug targets.

    Science.gov (United States)

    Vinayagam, Arunachalam; Gibson, Travis E; Lee, Ho-Joon; Yilmazel, Bahar; Roesel, Charles; Hu, Yanhui; Kwon, Young; Sharma, Amitabh; Liu, Yang-Yu; Perrimon, Norbert; Barabási, Albert-László

    2016-05-03

    The protein-protein interaction (PPI) network is crucial for cellular information processing and decision-making. With suitable inputs, PPI networks drive the cells to diverse functional outcomes such as cell proliferation or cell death. Here, we characterize the structural controllability of a large directed human PPI network comprising 6,339 proteins and 34,813 interactions. This network allows us to classify proteins as "indispensable," "neutral," or "dispensable," which correlates to increasing, no effect, or decreasing the number of driver nodes in the network upon removal of that protein. We find that 21% of the proteins in the PPI network are indispensable. Interestingly, these indispensable proteins are the primary targets of disease-causing mutations, human viruses, and drugs, suggesting that altering a network's control property is critical for the transition between healthy and disease states. Furthermore, analyzing copy number alterations data from 1,547 cancer patients reveals that 56 genes that are frequently amplified or deleted in nine different cancers are indispensable. Among the 56 genes, 46 of them have not been previously associated with cancer. This suggests that controllability analysis is very useful in identifying novel disease genes and potential drug targets.

  8. 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.

  9. 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

    2016-03-01

    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.

  10. Toward Understanding Pore Formation and Mobility during Controlled Directional Solidification in a Microgravity Environment Investigation (PFMI)

    Science.gov (United States)

    Grugel, Richard N.; Anilkumar, A. V.; Luz, Paul; Jeter, Linda; Volz, Martin P.; Spivey, Reggie; Smith, G.

    2003-01-01

    The generation and inclusion of detrimental porosity, e.g., pipes and rattails can occur during controlled directional solidification processing. The origin of these defects is generally attributed to gas evolution and entrapment during solidification of the melt. On Earth, owing to buoyancy, an initiated bubble can rapidly rise through the liquid melt and pop at the surface; this is obviously not ensured in a low gravity or microgravity environment. Clearly, porosity generation and inclusion is detrimental to conducting any meaningful solidification-science studies in microgravity. Thus it is essential that model experiments be conducted in microgravity, to understand the details of the generation and mobility of porosity, so that methods can be found to eliminate it. In hindsight, this is particularly relevant given the results of the previous directional solidification experiments conducted in Space. The current International Space Station (ISS) Microgravity Science Glovebox (MSG) investigation addresses the central issue of porosity formation and mobility during controlled directional solidification processing in microgravity. The study will be done using a transparent metal-analogue material, succinonitrile (SCN) and succinonitrile-water 'alloys', so that direct observation and recording of pore generation and mobility can be made during the experiments. Succinonitrile is particularly well suited for the proposed investigation because it is transparent, it solidifies in a manner analogous to most metals, it has a convenient melting point, its material properties are well characterized and, it has been successfully used in previous microgravity experiments. The PFMI experiment will be launched on the UF-2, STS-111 flight. Highlighting the porosity development problem in metal alloys during microgravity processing, the poster will describe: (i) the intent of the proposed experiments, (ii) the theoretical rationale behind using SCN as the study material for

  11. Real-time comparison of conventional direct control and pattern recognition myoelectric control in a two-dimensional Fitts' law style test.

    Science.gov (United States)

    Wurth, Sophie M; Hargrove, Levi J

    2013-01-01

    Few studies have directly compared real-time control performance of pattern recognition to direct control for the next generation of myoelectric controlled upper limb prostheses. Many different implementations of pattern recognition control have been proposed, with minor differentiations in the feature sets and classifiers. An objective and generalizable evaluation tool quantifying the control performance, other than classification accuracy, is needed. This paper used the implementation of such a tool through the design of a target acquisition test, similar to a Fitts' law test, relating movement time of the target acquisition to the difficulty of the target, for a given control strategy. Performance metrics such as throughput (bits/sec), completion rate (%) and path efficiency (%) allow for a complete evaluation of the described strategies. We compared direct control and pattern recognition control with the proposed test and found that 1) the test was valid for control system evaluation by following Fitts' law with high coefficients of determination for both types of control and 2) that pattern recognition significantly outperformed direct control in throughput with similar completion rates and path efficiencies. In this framework, the present pilot study supports pattern recognition as a promising strategy and forms a basis for the development of a general and objective tool for the performance evaluation of upper limb control strategies.

  12. Design and Modeling Improved Direct Torque Control of Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    Omid Moradi

    2014-07-01

    Full Text Available This paper studies most commonly used electric driving method of induction motors (IM. Direct torque control (DTC have been widely commercialized in induction motor drives, with each being favored by its supporters. In this paper, the dynamic performance of these drives for an electric vehicle application is examined, and sensitivities to parameter variations affecting this dynamic performance are explored by jacobian matrix in which the sensitivities of torque, speed, and other desired variables or outputs are estimated relative to change in motor parameters. Key performance measures include torque and speed transients. The switching scheme of these drive is a switching table. Both the overshoot and the settling time of DTC are really small

  13. 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.

  14. Controlling the onset of turbulence by streamwise traveling waves. Part 2. Direct numerical simulations

    CERN Document Server

    Lieu, Binh K; Jovanović, Mihailo R

    2010-01-01

    This work builds on and confirms the theoretical findings of Part 1 of this paper, Moarref & Jovanovi\\'c (2010). We use direct numerical simulations of the Navier-Stokes equations to assess the efficacy of blowing and suction in the form of streamwise traveling waves for controlling the onset of turbulence in a channel flow. We highlight the effects of the modified base flow on the dynamics of velocity fluctuations and net power balance. Our simulations verify the theoretical predictions of Part 1 that the upstream traveling waves promote turbulence even when the uncontrolled flow stays laminar. On the other hand, the downstream traveling waves with parameters selected in Part 1 are capable of reducing the fluctuations' kinetic energy, thereby maintaining the laminar flow. In flows driven by a fixed pressure gradient, a positive net efficiency as large as 25 % relative to the uncontrolled turbulent flow can be achieved with downstream waves. Furthermore, we show that these waves can also relaminarize full...

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

    Directory of Open Access Journals (Sweden)

    Yasuto Inukai

    2016-07-01

    Full Text Available 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.

  16. 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

  17. 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

  18. Social Control Disclosure and Accountability of Direct Money Program in Rio de Janeiro’s Schools

    Directory of Open Access Journals (Sweden)

    Ana Cristina de Oliveira Medeiros

    2016-12-01

    Full Text Available Education in Brazil have expanded the debate concerning the quality offered, as well as being a constitutional guarantee, there are the State's efforts in the allocation of financial resources annually. In the case of Basic Education was created in 2007 the Direct Money in School Program (DMSP that the Union transfers financial assistance to state and local public schools, and encourage widespread participation in resource management. Thus, the study’s objective was to investigate how civil society involved in the management of public resources of TSA, in a descriptive research with a quantitative and qualitative approach. The data collection was a documentary research: 29 accounts rendered digitized Direct Money in School Program (DMSP from schools and day care centers located in the municipality of Rio de Janeiro for the year 2012. Consolidating research, we sought to understand the perception of the Director of School / Day Care and President of the Community Council-School on the subject employing a questionnaire. In addition to the Audit Services scanned the TSA was checked for evidence of compliance with the principle of accountability and encouraging the social control in the electronic media. The results show the need to improve the participation of civil society, given that this study found that schools/nurseries do not provide the program information on official websites, minimizing transparency, and there is the existence of oversight failures in the assessment of benefits accounts and composition of the Councils.

  19. 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.

  20. A Direct Design from Input/Output Data of Fault-Tolerant Control System Based on GIMC Structure

    Science.gov (United States)

    Sakuishi, Tsubasa; Yubai, Kazuhiro; Hirai, Junji

    This paper deals with a design method of fault-tolerant control system based on Generalized Internal Model Control (GIMC) structure consisting of a standard outer loop feedback controller and an extra inner loop controller. The distinguished feature of GIMC structure is that the controller design for performance and robustness may be done separately. The outer loop controller is designed for nominal performance using some controller synthesis to meet (nominal) control specification, while the inner loop controller is designed to make a trade-off between robustness and performance. This feature is suitable for fault-tolerant control. The outer loop controller is designed for fault-free case, and the inner loop controller for faulty case. In the conventional methods, the inner loop controller is designed to maximize the robust stability margin without information on fault. Therefore, the performance in the faulty case tends to become conservative. In this paper, the inner loop controller is directly designed from experimental data collected from the faulty system. Since the collected data contains information on the fault, conservativeness in the conventional methods is decreased. The inner loop controller is designed by Virtual Reference Feedback Tuning (VRFT). VRFT is a direct design method from input-output data without identifying any models. Since complexity of the controller can be specified by the designer, no complexity reduction has to be required, which becomes advantageous upon implementation. The effectiveness of the proposed design method is confirmed by an experiment.

  1. 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

  2. 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)

  3. 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.

  4. 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.

  5. Controlling speed and direction during interception: an affordance-based approach.

    Science.gov (United States)

    Bastin, Julien; Fajen, Brett R; Montagne, Gilles

    2010-04-01

    The coordination of direction and speed of self-motion when intercepting a target moving parallel to the ground plane was examined. Subjects viewed a computer-generated environment comprised of a textured ground plane and a moving target. Turning rate was controlled using a steering wheel and speed was controlled using a foot pedal. It was hypothesized that these two degrees of freedom would be coordinated such that the speed required to intercept the target (i.e., the ideal speed) would be maintained below the subject's maximum possible speed. As predicted, subjects turned toward the target when ideal speed was less than maximum speed and ahead of the target when ideal speed was greater than maximum speed. When behavior was compared across groups with different maximum speed capabilities, it was found that the ratio of ideal to maximum speed was invariant across groups at critical points of both steering and speed adjustments. Finally, subjects rapidly recalibrated to a sudden increase or decrease in maximum speed. The results suggest that actors coordinate steering and speed during interception in a way that takes into account the limits on their action capabilities. Discussion focuses on the role of calibration and the implications of the present findings for existing models of visually guided interception.

  6. The role of online visual feedback for the control of target-directed and allocentric hand movements.

    Science.gov (United States)

    Thaler, Lore; Goodale, Melvyn A

    2011-02-01

    Studies that have investigated how sensory feedback about the moving hand is used to control hand movements have relied on paradigms such as pointing or reaching that require subjects to acquire target locations. In the context of these target-directed tasks, it has been found repeatedly that the human sensory-motor system relies heavily on visual feedback to control the ongoing movement. This finding has been formalized within the framework of statistical optimality according to which different sources of sensory feedback are combined such as to minimize variance in sensory information during movement control. Importantly, however, many hand movements that people perform every day are not target-directed, but based on allocentric (object-centered) visual information. Examples of allocentric movements are gesture imitation, drawing, or copying. Here we tested if visual feedback about the moving hand is used in the same way to control target-directed and allocentric hand movements. The results show that visual feedback is used significantly more to reduce movement scatter in the target-directed as compared with the allocentric movement task. Furthermore, we found that differences in the use of visual feedback between target-directed and allocentric hand movements cannot be explained based on differences in uncertainty about the movement goal. We conclude that the role played by visual feedback for movement control is fundamentally different for target-directed and allocentric movements. The results suggest that current computational and neural models of sensorimotor control that are based entirely on data derived from target-directed paradigms have to be modified to accommodate performance in the allocentric tasks used in our experiments. As a consequence, the results cast doubt on the idea that models of sensorimotor control developed exclusively from data obtained in target-directed paradigms are also valid in the context of allocentric tasks, such as drawing

  7. 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.

  8. 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.

  9. Real Time Self-Directed MBE Flux Control Incorporation In Situ Ellipsometry. Phase 1

    Science.gov (United States)

    1992-11-01

    representation. It shows the PID controllers for the Knudsen Cells and substrate holder, the Kntdsen Cell shutters, cryo-sliroud sensor, flux beam...Shutter - "PID Control Opening.OO •= Cryo-Shroud Transient Interface Compensatot KNUDSE 6 User Interface User Interface PID controllers PID Control...S h u t te r PID controe ControlFIUR 45 MBE S Cryo-Shroude KNUS >. User Interface PID Control PID controllers Inefc FIGURE 45. MBE System Health

  10. Performance Analysis of Video PHY Controller Using Unidirection and Bi-directional IO Standard via 7 Series FPGA

    DEFF Research Database (Denmark)

    Das, Bhagwan; Abdullah, M F L; Hussain, Dil muhammed Akbar

    2017-01-01

    graphics consumes more power, this creates a need of designing the low power design for Video PHY controller. In this paper, the performance of Video PHY controller is analyzed by comparing the power consumption of unidirectional and bi-directional IO Standard over 7 series FPGA. It is determined...

  11. A High Performance Space Vector Modulation - Direct Torque Controlled Induction Machine Drive based on Stator Flux Orientation Technique

    Directory of Open Access Journals (Sweden)

    BELMADANI, B.

    2009-06-01

    Full Text Available This paper proposes the design and implementation of a novel direct torque controlled induction machine drive system. The control system enjoys the advantages of stator vector control and conventional direct torque control and avoids some of the implementation difficulties of either of the two control methods. The stator vector control principal is used to keep constant the amplitude of stator flux vector at rated value, and to develop the relationship between the machine torque and the rotating speed of the stator flux vector. Thus, the machine torque can be regulated to generate the stator angular speed, which becomes a command signal and permits to overcome the problem of its estimation. Furthermore, with the combined control methods, the reference stator voltage vector can be generated and proportional-integral controllers and space vector modulation technique can be used to obtain fixed switching frequency and low torque ripple. Simulation experiments results indicate that, with the proposed scheme, a precise control of the stator flux and machine torque can be achieved. Compared to conventional direct torque control, presented method is easily implemented, and the steady performances of ripples of both torque and flux are considerably improved.

  12. 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.

  13. Improved Direct Deadbeat Voltage Control with an Actively Damped Inductor-Capacitor Plant Model in an Islanded AC Microgrid

    Directory of Open Access Journals (Sweden)

    Jaehong Kim

    2016-11-01

    Full Text Available A direct deadbeat voltage control design method for inverter-based microgrid applications is proposed in this paper. When the inductor-capacitor (LC filter output voltage is directly controlled using voltage source inverters (VSIs, the plant dynamics exhibit second-order resonant characteristics with a load current disturbance. To effectively damp the resonance caused by the output LC filter, an active damping strategy that does not cause additional energy loss is utilized. The proposed direct deadbeat voltage control law is devised from a detailed, actively damped LC plant model. The proposed deadbeat control method enhances voltage control performance owing to its better disturbance rejection capability than the conventional deadbeat or proportional-integral-based control methods. The most important advantage of the proposed deadbeat control method is that it makes the deadbeat control more robust by bringing discrete closed-loop poles closer to the origin. Simulation and experimental results are shown to verify the enhanced voltage control performance and stability of the proposed voltage control method.

  14. 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.

  15. 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.

  16. Coordinated orbit-tracking control of second-order non-linear agents with directed communication topologies

    Science.gov (United States)

    Chen, Y.-Y.; Zhang, Y.; Liu, C.-L.; Wei, P.

    2016-12-01

    This paper deals with two-dimensional and three-dimensional cooperative control of multiple agents formation tracking a set of given closed orbits, where each agent has intrinsic second-order non-linear dynamics and the communication topology among agents is directed. By using our previous curve extension method, the cooperative control system can be regarded as a cascade system composed of the orbit-tracking subsystem and the formation subsystem with the orbit-tracking error as input. A novel solution is established by separatively designing the orbit-tracking control law and the formation control protocol ignoring the perturbation at first and then applying input-to-state stability theory to analyse the asymptotic stability of the cascade system. It is shown that the closed-loop system is asymptotic stability if the directed communication topology contains a directed spanning tree. The effectiveness of the analytical results is verified by numerical simulations.

  17. Acetalated dextran encapsulated AR-12 as a host-directed therapy to control Salmonella infection.

    Science.gov (United States)

    Hoang, Ky V; Borteh, Hassan M; Rajaram, Murugesan V S; Peine, Kevin J; Curry, Heather; Collier, Michael A; Homsy, Michael L; Bachelder, Eric M; Gunn, John S; Schlesinger, Larry S; Ainslie, Kristy M

    2014-12-30

    AR-12 has been evaluated in clinical trials as an anti-cancer agent but also has demonstrated host-directed, broad-spectrum clearance of bacteria. We have previously shown that AR-12 has activity in vitro against Salmonella enterica serovar Typhimurium and Francisella species by inducing autophagy and other host immune pathways. AR-12 treatment of S. Typhimurium-infected mice resulted in a 10-fold reduction in bacterial load in the liver and spleen and an increased survival time. However, AR-12 treatment did not protect mice from death, likely due poor formulation. In the current study, AR-12 was encapsulated in a microparticulate carrier formulated from the novel degradable biopolymer acetalated dextran (Ace-DEX) and subsequently evaluated for its activity in human monocyte-derived macrophages (hMDMs). Our results show that hMDMs efficiently internalized Ace-DEX microparticles (MPs), and that encapsulation significantly reduced host cell cytotoxicity compared to unencapsulated AR-12. Efficient macrophage internalization of AR-12 loaded MPs (AR-12/MPs) was further demonstrated by autophagosome formation that was comparable to free AR-12 and resulted in enhanced clearance of intracellular Salmonella. Taken together, these studies provide support that Ace-DEX encapsulated AR-12 may be a promising new therapeutic agent to control intracellular bacterial pathogens of macrophages by targeting delivery and reducing drug toxicity.

  18. Soft Plumbing: Direct-Writing and Controllable Perfusion of Tubular Soft Materials

    Science.gov (United States)

    Guenther, Axel; Omoruwa, Patricia; Chen, Haotian; McAllister, Arianna; Jeronimo, Mark; Malladi, Shashi; Hakimi, Navid; Cao, Li; Ramchandran, Arun

    2016-11-01

    Tubular and ductular structures are abundant in tissues in a wide variety of diameters, wall thicknesses, and compositions. In spite of their relevance to engineered tissues, organs-on-chips and soft robotics, the rapid and consistent preparation of tubular structures remains a challenge. Here, we use a microfabricated printhead to direct-write biopolymeric tubes with dimensional and compositional control. A biopolymer solution is introduced to the center layer of the printhead, and the confining fluids to the top and the bottom layers. The radially flowing biopolymer solution is sandwiched between confining solutions that initiate gelation, initially assuming the shape of a funnel until emerging through a cylindrical confinement as a continuous biopolymer tube. Tubular constructs of sodium alginate and collagen I were obtained with inner diameters (0.6-2.2mm) and wall thicknesses (0.1-0.4mm) in favorable agreement with predictions of analytical models. We obtained homogeneous tubes with smooth and buckled walls and heterotypic constructs that possessed compositions that vary along the tube circumference or radius. Ductular soft materials were reversibly hosted in 3D printed fluidic devices for the perfusion at well-defined transmural pressures to explore the rich variety of dynamical features associated with collapsible tubes that include buckling, complete collapse, and self-oscillation.

  19. 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.

  20. The RPG gene of Medicago truncatula controls Rhizobium-directed polar growth during infection.

    Science.gov (United States)

    Arrighi, Jean-François; Godfroy, Olivier; de Billy, Françoise; Saurat, Olivier; Jauneau, Alain; Gough, Clare

    2008-07-15

    Rhizobia can infect roots of host legume plants and induce new organs called nodules, in which they fix atmospheric nitrogen. Infection generally starts with root hair curling, then proceeds inside newly formed, intracellular tubular structures called infection threads. A successful symbiotic interaction relies on infection threads advancing rapidly at their tips by polar growth through successive cell layers of the root toward developing nodule primordia. To identify a plant component that controls this tip growth process, we characterized a symbiotic mutant of Medicago truncatula, called rpg for rhizobium-directed polar growth. In this mutant, nitrogen-fixing nodules were rarely formed due to abnormally thick and slowly progressing infection threads. Root hair curling was also abnormal, indicating that the RPG gene fulfils an essential function in the process whereby rhizobia manage to dominate the process of induced tip growth for root hair infection. Map-based cloning of RPG revealed a member of a previously unknown plant-specific gene family encoding putative long coiled-coil proteins we have called RRPs (RPG-related proteins) and characterized by an "RRP domain" specific to this family. RPG expression was strongly associated with rhizobial infection, and the RPG protein showed a nuclear localization, indicating that this symbiotic gene constitutes an important component of symbiotic signaling.

  1. Doses under automatic exposure control (AEC) for direct digital radiographic (DDR) X-ray systems.

    Science.gov (United States)

    Bowden, Louise; Faulkner, Ronan; Clancy, Conor; Gallagher, Aoife; Devine, Mark; Gorman, Dermot; O'Reilly, Geraldine; Dowling, Anita

    2011-09-01

    Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 μGy with the antiscatter grid in place and 4.0 μGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 μGy with the antiscatter grid in place and 5.4 μGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose.

  2. Harmonic reduction of Direct Torque Control of six-phase induction motor.

    Science.gov (United States)

    Taheri, A

    2016-07-01

    In this paper, a new switching method in Direct Torque Control (DTC) of a six-phase induction machine for reduction of current harmonics is introduced. Selecting a suitable vector in each sampling period is an ordinal method in the ST-DTC drive of a six-phase induction machine. The six-phase induction machine has 64 voltage vectors and divided further into four groups. In the proposed DTC method, the suitable voltage vectors are selected from two vector groups. By a suitable selection of two vectors in each sampling period, the harmonic amplitude is decreased more, in and various comparison to that of the ST-DTC drive. The harmonics loss is greater reduced, while the electromechanical energy is decreased with switching loss showing a little increase. Spectrum analysis of the phase current in the standard and new switching table DTC of the six-phase induction machine and determination for the amplitude of each harmonics is proposed in this paper. The proposed method has a less sampling time in comparison to the ordinary method. The Harmonic analyses of the current in the low and high speed shows the performance of the presented method. The simplicity of the proposed method and its implementation without any extra hardware is other advantages of the proposed method. The simulation and experimental results show the preference of the proposed method.

  3. Peroxone mineralization of chemical oxygen demand for direct potable water reuse: Kinetics and process control.

    Science.gov (United States)

    Wu, Tingting; Englehardt, James D

    2015-04-15

    Mineralization of organics in secondary effluent by the peroxone process was studied at a direct potable water reuse research treatment system serving an occupied four-bedroom, four bath university residence hall apartment. Organic concentrations were measured as chemical oxygen demand (COD) and kinetic runs were monitored at varying O3/H2O2 dosages and ratios. COD degradation could be accurately described as the parallel pseudo-1st order decay of rapidly and slowly-oxidizable fractions, and effluent COD was reduced to below the detection limit (water, and a relationship is proposed and demonstrated to estimate the pseudo-first order rate constant for design purposes. At this O3/H2O2 mass ratio, ORP and dissolved ozone were found to be useful process control indicators for monitoring COD mineralization in secondary effluent. Moreover, an average second order rate constant for OH oxidation of secondary effluent organics (measured as MCOD) was found to be 1.24 × 10(7) ± 0.64 × 10(7) M(-1) S(-1). The electric energy demand of the peroxone process is estimated at 1.73-2.49 kW h electric energy for removal of one log COD in 1 m(3) secondary effluent, comparable to the energy required for desalination of medium strength seawater. Advantages/disadvantages of the two processes for municipal wastewater reuse are discussed.

  4. 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.

  5. Direct ELISA kits as a sensitive and selective screening method for abstinence control in urine.

    Science.gov (United States)

    Kirschbaum, Katrin M; Musshoff, Frank; Wilbert, Ansgar; Röhrich, Jörg; Madea, Burkhard

    2011-04-15

    In 2009 cutoff values of assessment criteria to testify abstinence control in order to estimate driving ability were standardized in Germany. The cutoff values are lower than required in existing guidelines like SAMHSA and there is critical discussion about detection of low concentrations by using immunoassay, especially concerning amphetamines in urine (50 ng/ml). In this study Direct ELISA kits were tested for their applicability to identify the absence of amphetamines, cannabinoids, opiates, cocaine, methadone and benzodiazepines in urine. Results were confirmed by LC/MS or GC/MS analyses. Sensitivity, specificity, predictive values (positive as well as negative) and overall misclassification rates were evaluated by contingency tables and were compared to ROC-analyses. Sensitivity results as well as specificity results were satisfying showing sensitivity values higher than 96% for each analyte. The amphetamine test we used showed sensitivity and specificity of 100% and 88%, respectively, even if amphetamine tests usually react with high cross-reactivity. Our study results include high discrimination at required cutoff values between positives and negatives for each drug group and demonstrate that immunological tests complying with requirements of current decreased urine cutoff values for assessment of driving ability do exist.

  6. 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.

  7. The development of an UAV borne direct georeferenced photogrammetric platform for Ground Control Point free applications.

    Science.gov (United States)

    Chiang, Kai-Wei; Tsai, Meng-Lun; Chu, Chien-Hsun

    2012-01-01

    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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. The strategic control of gaze direction in the Tower-of-London task.

    Science.gov (United States)

    Hodgson, T L; Bajwa, A; Owen, A M; Kennard, C

    2000-09-01

    In this paper, we describe a novel approach to the study of problem solving involving the detailed analysis of natural scanning eye movements during the "one-touch" Tower-of-London (TOL) task. We showed subjects a series of pictures depicting two arrangements of colored balls in pockets within the upper and lower halves of a computer display. The task was to plan (but not to execute) the shortest movement sequence required to rearrange the balls in one half of the display (the Workspace) to match the arrangement in the opposite half (the Goalspace) and indicate the minimum number of moves required for problem solution. We report that subjects are more likely to look towards the Goalspace in the initial period after picture presentation, but bias gaze towards the Workspace during the middle of trials. Towards the end of a trial, subjects are once again more likely to fixate the Goalspace. This pattern is found regardless of whether the subjects solve problems by rearranging the balls in the lower or upper visual fields, demonstrating that this strategy correlates with discrete phases in problem solving. A second experiment showed that efficient planners direct their gaze selectively towards the problem critical balls in the Workspace. In contrast, individuals who make errors spend more time looking at irrelevant items and are strongly influenced by the movement strategy needed to solve the preceding problem. We conclude that efficient solution of the TOL requires the capacity to generate and flexibly shift between control sets, including those underlying ocular scanning. The role of working memory and the prefrontal cerebral cortex in the task are discussed.

  14. Micronized ethylcellulose used for designing a directly compressed time-controlled disintegration tablet.

    Science.gov (United States)

    Lin, S Y; Lin, K H; Li, M J

    2001-02-23

    Ethylcellulose (EC) of varying particle sizes has been used as an outer coating layer to design a novel dry-coated tablet with time-controlled drug release. This dry-coated tablet, containing a core tablet of sodium diclofenac and an outer coating layer of EC, was prepared by direct compression. The drug release from dry-coated tablet exhibited an initial lag period that was dependent on the particle size of the EC powder, followed by a stage of rapid drug release. The smaller the EC particle size used the longer the lag time obtained, suggesting the particle size of EC powder could modulate the timing of drug release from such a dry-coated tablet. The period of the lag time for sodium diclofenac released from dry-coated tablets was correlated with the penetration distance of the solvent into dry-coated tablet by an in vitro dye penetration study. The densest packing of EC powders appeared on the upper and lower surfaces of dry-coated tablet after compression, resulting in a tight structure yielding a slower penetration of the solvent. Whereas loose packing of EC powders occurred in the middle of the lateral surface of dry-coated tablet, this loosely packed surface readily allowed solvent penetration and that finally caused the splitting of tablet shell into two halves in the dissolution medium. The results suggest that these dry-coated tablets prepared with different particle sizes of EC powder as an outer coating layer might offer a desirable release profile for drug delivery at the predetermined times and/or sites.

  15. Controllable Direct-Writing of Serpentine Micro/Nano Structures via Low Voltage Electrospinning

    OpenAIRE

    Feiyu Fang; Xin Chen; Zefeng Du; Ziming Zhu; Xindu Chen; Han Wang; Peixuan Wu

    2015-01-01

    Micro/nanofibers prepared by direct-writing using an electrospinning (ES) technique have drawn more attention recently owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW) process was developed to directly write serpentine micro/nano structures suitable for the fabrication of micro devices. This fabrication ability will realize the application of electrospun-nanofiber-based wiring of structu...

  16. 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

    -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......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...

  17. 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.

  18. 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.

  19. 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.

  20. Real-Time Control of Uni-Directional Liquid Spreading on a Half-Cone Nanoshell Array

    Science.gov (United States)

    Ai, Bin; Wang, Limin; Möhwald, Helmuth; Yu, Ye; Zhao, Zhiyuan; Zhou, Ziwei; Zhang, Gang; Lin, Quan

    2014-10-01

    Half-cone nanoshell arrays, fabricated by a simple and efficient colloidal lithography method, enable uni-directional liquid spreading on their hydrophilic asymmetric nanostructured surface. The preferred direction of the liquid flow is reversed when the surface is made hydrophobic. Accordingly, poly(N-isopropyl-acrylamide) is polymerized onto the surface for in-site controlling the transition of liquid spreading direction via its temperature dependent hydrophobicity. Furthermore, we also explain theoretically, that the spreading direction on hexagonal nanocone arrays is independent of the lattice orientation and only depends on the slanting direction. The insights gained from this work offer new opportunities for smart microfluidics, water harvesting and making use of other wetting conditions on demand.

  1. Magnetic oxide nanowires with strain-controlled uniaxial magnetic anisotropy direction

    NARCIS (Netherlands)

    Mathews, M.; Jansen, R.; Rijnders, G.; Lodder, J.C.; Blank, D.H.A.

    2009-01-01

    While magnetic nanowires generally have a preferential magnetization direction along the wire axis to minimize magnetostatic energy, it is shown here for epitaxial magnetic oxide nanowires that substrate-induced strain can be used to tailor the magnetic easy axis in any direction. La0.67Sr0.33MnO3 (

  2. Goal directed reaching and postural control in supine position in healthy infants

    NARCIS (Netherlands)

    Fallang, B; Saugstad, OD; Hadders-Algra, M

    2000-01-01

    The present study focussed on the development and interaction of reaching and posture in supine position in young infants. The kinematics of goal directed reaches and the concurrent ground reaction forces of the total body centre of pressure (COP) in cranial-caudal and medial-lateral direction were

  3. System-wide hybrid MPC-PID control of a continuous pharmaceutical tablet manufacturing process via direct compaction.

    Science.gov (United States)

    Singh, Ravendra; Ierapetritou, Marianthi; Ramachandran, Rohit

    2013-11-01

    The next generation of QbD based pharmaceutical products will be manufactured through continuous processing. This will allow the integration of online/inline monitoring tools, coupled with an efficient advanced model-based feedback control systems, to achieve precise control of process variables, so that the predefined product quality can be achieved consistently. The direct compaction process considered in this study is highly interactive and involves time delays for a number of process variables due to sensor placements, process equipment dimensions, and the flow characteristics of the solid material. A simple feedback regulatory control system (e.g., PI(D)) by itself may not be sufficient to achieve the tight process control that is mandated by regulatory authorities. The process presented herein comprises of coupled dynamics involving slow and fast responses, indicating the requirement of a hybrid control scheme such as a combined MPC-PID control scheme. In this manuscript, an efficient system-wide hybrid control strategy for an integrated continuous pharmaceutical tablet manufacturing process via direct compaction has been designed. The designed control system is a hybrid scheme of MPC-PID control. An effective controller parameter tuning strategy involving an ITAE method coupled with an optimization strategy has been used for tuning of both MPC and PID parameters. The designed hybrid control system has been implemented in a first-principles model-based flowsheet that was simulated in gPROMS (Process System Enterprise). Results demonstrate enhanced performance of critical quality attributes (CQAs) under the hybrid control scheme compared to only PID or MPC control schemes, illustrating the potential of a hybrid control scheme in improving pharmaceutical manufacturing operations.

  4. Active Flow Control of Lifting Surface With Flap-Current Activities and Future Directions

    Science.gov (United States)

    Ahmadi, G.; Marzocca, P.; Jha, R.; Alstorm, B.; Obied, S.; Kabir, P.; Shahrabi, A.

    2010-01-01

    The main objective is to develop effective control strategies for separation control of an airfoil with a single hinge flap. The specific objectives are: Develop an active control architecture for flow control around an airfoil with flap. Design, fabricate, a wind tunnel test of a high lift wing (with flap) with integrated actuators and sensors. Design, development and fabrication of synthetic jet actuators. Develop appropriate control strategy for application to the airfoil. Wind tunnel testing of the high lift wing at various angles of attack and flap positions with closed loop control.

  5. 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.

  6. A DDC-based capacity controller of a direct expansion (DX) air conditioning (A/C) unit for simultaneous indoor air temperature and humidity control - Pt. 1: Control algorithms and preliminary controllability tests

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zheng [Institute of Air Conditioning, China Academy of Building Research, Beijing 100013 (China); Deng, Shiming [Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR (China)

    2007-01-15

    For residential buildings located in the subtropics, direct expansion (DX) air conditioning (A/C) units are commonly used. Most DX A/C units are currently equipped with single-speed compressors and supply fans, relying on on-off cycling compressors as a low-cost approach to maintain only indoor air dry-bulb temperature, resulting in either space overcooling or an uncontrolled equilibrium indoor relative humidity (RH) level. With the rapid development of A/C industry, the use of variable-speed compressor and supply fan has become more and more prevalent and practical. This paper, the first part of a two-part series, reports on the development of a novel direct digital control (DDC)-based capacity controller for a DX A/C unit having variable-speed compressor and supply fan to simultaneously control indoor air temperature and RH in a conditioned space served by the DX A/C unit. The controller is the first of its kind as a composite parameter, sensible heat ratio (SHR), is used as a controlled parameter. The core element of the capacity controller, a numerical calculation algorithm (NCA) is firstly presented. This is followed by reporting the results of preliminary controllability tests of the DDC-based capacity controller, which suggested that the controller developed could achieve a reasonable control accuracy, but with room for improvement with respect to control sensitivity. Part II of the two-part series reports on the further development of the controller to improve its control sensitivity, and the results of associated controllability tests. (author)

  7. 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 ...

  8. Direct implementation of a scalable non-local multi-qubit controlled phase gate via optical fibres and adiabatic passage

    Institute of Scientific and Technical Information of China (English)

    Tang Yao-Xiang; Lin Xiu-Min; Lin Gong-Wei; Chen Li-Bo; Huang Xiu-Hua

    2008-01-01

    This paper presents a direct implementation scheme of the non-local multi-qubit controlled phase gate by using optical fibres and adiabatic passage. The smaller operation number for implementing the multi-qubit controlled phase gate and needlessness for addressing individually save physical resource and lower the difficulties of experiment. Meanwhile, the scheme is immune from some decoherence effects such as the atomic spontaneous emission and fibre loss. In principle, it is scalable.

  9. Modeling and Control of High-Voltage Direct-Current Transmission Systems: From Theory to Practice and Back

    OpenAIRE

    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...

  10. Modeling of Ultrasonically Generated Liquid-Liquid Dispersions During Controlled Directional Solidification

    Science.gov (United States)

    Grugel, R. N.; Fedoseyev, A. I.

    2000-01-01

    There are innumerable two-component systems in which two very different liquid phases co-exist in equilibrium over a range of temperature and composition, e.g., oil and water, salt fluxes and solders, aluminum and lead. Often it is of practical concern to fabricate a solid component consisting of a uniform dispersion of one phase in the other. Unfortunately, uniform microstructural development during solidification of two immiscible liquids is hampered by inherent, often large, density differences between the phases that lead to severe segregation. Uniformity is also compromised by preferential wetting and coalescence phenomena. It is, however, well known that ultrasonic energy can initiate and maintain a fine liquid-liquid dispersion. The work presented here extends that observation by application of ultrasonic energy to promote uniform phase incorporation during controlled directional solidification. To this end experiments with the transparent organic, immiscible, succinonitrile-glycerol system were conducted and the numerous processing parameters associated with this technique were evaluated in view of optimizing dispersion uniformity. In view of the initial experimental results a model that predicts the dispersed liquid droplet size as a function of material properties, sample geometry, and applied energy has been developed. In the mathematical model we consider the ultrasonic field in an experimental ampoule of length L and diameter D induced by a probe having a vibration frequency of f=2OKhz (circular frequency omega = 2 pi f). The amplitude is adjustable from A=65 to 13Omicrons. The probe tip diameter is d, the liquid has a density of p, in which the speed of sound and surface tension are, respectively, c and sigma. The mathematical model and numerical investigation for the experiments [1] is done using the following assumptions: (i) The droplet size is small in comparison to the sound wave length; (ii) The forces between droplets are neglected (relative

  11. Controllable Direct-Writing of Serpentine Micro/Nano Structures via Low Voltage Electrospinning

    Directory of Open Access Journals (Sweden)

    Feiyu Fang

    2015-08-01

    Full Text Available Micro/nanofibers prepared by direct-writing using an electrospinning (ES technique have drawn more attention recently owing to their intriguing physical properties and great potential as building blocks for micro/nanoscale devices. In this work, a wavy direct-writing (WDW process was developed to directly write serpentine micro/nano structures suitable for the fabrication of micro devices. This fabrication ability will realize the application of electrospun-nanofiber-based wiring of structural and functional components in microelectronics, MEMS, sensor, and micro optoelectronics devices, and, especially, paves the way for the application of electrospinning in printing serpentine interconnector of large-area organic stretchable electronics.

  12. Sensor Based Process Control (SBPC) Laboratories Directed Research and Development (LDRD)

    Energy Technology Data Exchange (ETDEWEB)

    Wronosky, J.B.

    1993-03-01

    This report describes the activities and results of an LDRD entitled Sensor Based Process Control. This research examined the needs of the plating industry for monitor and control capabilities with particular emphasis on water effluent from rinse baths. A personal computer-based monitor and control development system was used as a test bed.

  13. A novel fuzzy logic direct torque controller for a permanent magnet synchronous motor with a field programmable gate array

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-jun; HUANG Sheng-hua; WAN Shan-ming; WU Fang

    2008-01-01

    A high-performance digital servo system built on the platform of a field programmable gate array (FPGA), a fully digitized hardware design scheme of a direct torque control (DTC) and a low speed permanent magnet synchronous motor (PMSM) is proposed. The DTC strategy of PMSM is described with Verilog hardware description language and is employed on-chip FPGA in accordance with the electronic design automation design methodology. Due to large torque ripples in low speed PMSM, the hysteresis controller in a conventional PMSM DTC was replaced by a fuzzy controller. This FPGA scheme integrates the direct torque controller strategy, the time speed measurement algorithm, the fuzzy regulating technique and the space vector pulse width modulation principle. Experimental results indicate the fuzzy controller can provide a controllable speed at 20 r min-1 and torque at 330 N m with satisfactory dynamic and static performance. Furthermore, the results show that this new control strategy decreases the torque ripple drastically and enhances control performance.

  14. 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...

  15. 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…

  16. Eye-based Direct Interaction for Environmental Control in Heterogeneous Smart Environments

    Science.gov (United States)

    Corno, Fulvio; Gale, Alastair; Majaranta, Päivi; Räihä, Kari-Jouko

    environmental control is the control, operation, and monitoring of an environment via intermediary technology such as a computer. Typically this means control of a domestic home.Within the scope of COGAIN, this environmental control concerns the control of the personal environment of a person (with or without a disability). This defines environmental control as the control of a home or domestic setting and those objects that are within that setting. Thus, we may say that environmental control systems enable anyone to operate a wide range of domestic appliances and other vital functions in the home by remote control. In recent years the problem of self-sufficiency for older people and people with a disability has attracted increasing attention and resources. The search for new solutions that can guarantee greater autonomy and a better quality of life has begun to exploit easily available state-of-the-art technology. Personal environmental control can be considered to be a comprehensive and effective aid, adaptable to the functional possibilities of the user and to their desired actions.

  17. Revisiting Controlled Quantum Secure Direct Communication Using a Non-symmetric Quantum Channel with Quantum Superdense Coding

    Institute of Scientific and Technical Information of China (English)

    HU Li-Yun; LIU Jun; FAN Hong-Yi; LIU Yi-Min; XIA Yan; ZHANG Zhan-Jun

    2008-01-01

    Recently Xia and Song [Phys. Left. 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 succeasfully 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.

  18. Entry dynamics of space shuttle orbiter with lateral-directional stability and control uncertainties at supersonic and hypersonic speeds

    Science.gov (United States)

    Stone, H. W.; Powell, R. W.

    1977-01-01

    A six-degree-of-freedom simulation analysis was conducted to examine the effects of the lateral-directional static aerodynamic stability and control uncertainties on the performance of the automatic (no manual inputs) entry-guidance and control systems of the space shuttle orbiter. To establish the acceptable boundaries of the uncertainties, the static aerodynamic characteristics were varied either by applying a multiplier to the aerodynamic parameter or by adding an increment. Control-system modifications were identified that decrease the sensitivity to off-nominal aerodynamics. With these modifications, the acceptable aerodynamic boundaries were determined.

  19. Markedly Improved Glycemic Control in Poorly Controlled Type 2 Diabetes following Direct Acting Antiviral Treatment of Genotype 1 Hepatitis C

    Directory of Open Access Journals (Sweden)

    Raymond Anthony Pashun

    2016-01-01

    Full Text Available Type 2 diabetes mellitus (T2DM is often associated with hepatitis C virus (HCV infection. Successful HCV treatment may improve glycemic control and potentially induce remission of T2DM. We report a case of an obese 52-year-old woman with mixed genotype 1a/1b HCV infection with compensated cirrhosis and a 10-year history of poorly controlled T2DM on insulin therapy. Following successful therapy with sofosbuvir, simeprevir, and ribavirin, her insulin requirements decreased and her glycosylated hemoglobin (HgA1c normalized despite weight gain. This case suggests an association between HCV and T2DM and the potential for significant improvement in glycemic control with eradication of HCV.

  20. Joystick control for powered mobility: current state of technology and future directions.

    Science.gov (United States)

    Dicianno, Brad E; Cooper, Rory A; Coltellaro, John

    2010-02-01

    Recent advancements in control interface technology have made the use of end devices such as power wheelchairs easier for individuals with disabilities, especially persons with movement disorders. In this article, we discuss the current state of control interface technology and the devices available clinically for power wheelchair control. We also discuss our research on novel hardware and software approaches that are revolutionizing joystick interface technology and allowing more customizability for individual users with special needs and abilities. Finally, we discuss the future of control interfaces and what research gaps remain.

  1. 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...... to 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...

  2. 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

  3. Lessons to be Learnt from Natural Control of HIV – Future Directions, Therapeutic and Preventive Implications

    Directory of Open Access Journals (Sweden)

    David eShasha

    2013-06-01

    Full Text Available Accumulating data generated from persons who naturally control HIV without the need for antiretroviral treatment has led to significant insights into the mechanisms of durable control of AIDS virus infection. At the center of this control is the HIV-specific CD8 T cell response, and the basis for this CD8-mediated control is gradually being revealed. Genome wide association studies coupled with HLA sequence data implicate the nature of the HLA-viral peptide interaction as the major genetic factor modulating durable control of HIV, but that host genetic factors account for only around 20% of the variability in control. Other factors including specific functional characteristics of the TCR clonotypes generated in vivo, targeting of vulnerable regions of the virus that lead to fitness impairing mutations, immune exhaustion and host restriction factors that limit HIV replication all have been shown to additionally contribute to control. Moreover, emerging data indicate that the CD8 T cell response may be critical for attempts to purge virus infected cells following activation of the latent reservoir, and thus lessons learned from elite controllers are likely to impact the eradication agenda. Ongoing efforts are also needed to understand and address the role of immune activation in disease progression, as it becomes increasingly clear that durable immune control in elite controllers comes at a cost. Taken together, the research achievements in the attempt to unlock the mechanisms behind natural control of HIV will continue to be an important source of insights and ideas in the continuous search after an effective HIV vaccine, and for the attempts to achieve a sterilizing or functional cure in HIV positive patients with progressive infection.

  4. Controlling the Directional Emission of Light by Periodic Arrays of Heterostructured Semiconductor Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Diedenhofen, S.L. [FOM Institute AMOLF, c/o Philips Research, High-Tech Campus 4, 5656 AE Eindhoven (Netherlands); Janssen, O.T.A.; Urbach, H.P. [Optics Research Group, Delft University of Technology, PO Box 5046, 2608 GA Delft (Netherlands); Hocevar, M. [Kavli Institute of Nanoscience, Quantum Transport, Delft University of Technology, 2600 GA Delft (Netherlands); Pierret, A.; Bakkers, E.P.A.M. [Philips Research Laboratories, High-Tech Campus 4, 5656 AE Eindhoven (Netherlands); Gomez Rivas, J. [Applied Physics, Photonics and Semiconductor Nanophysics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)

    2011-07-01

    We demonstrate experimentally the directional emission of light by InAsP segments embedded in InP nanowires. The nanowires are arranged in a periodic array, forming a 2D photonic crystal slab. The directionality of the emission is interpreted in terms of the preferential decay of the photoexcited nanowires and the InAsP segments into Bloch modes of the periodic structure. By simulating the emission of arrays of nanowires with the emitting segments located at different heights, we conclude that the position of this active region strongly influences the directionality and efficiency of the emission. Our results will help to improve the design of nanowire based LEDs and single photon sources.

  5. Controlling the directional emission of light by periodic arrays of heterostructured semiconductor nanowires.

    Science.gov (United States)

    Diedenhofen, Silke L; Janssen, Olaf T A; Hocevar, Moïra; Pierret, Aurélie; Bakkers, Erik P A M; Urbach, H Paul; Rivas, Jaime Gómez

    2011-07-26

    We demonstrate experimentally the directional emission of light by InAsP segments embedded in InP nanowires. The nanowires are arranged in a periodic array, forming a 2D photonic crystal slab. The directionality of the emission is interpreted in terms of the preferential decay of the photoexcited nanowires and the InAsP segments into Bloch modes of the periodic structure. By simulating the emission of arrays of nanowires with the emitting segments located at different heights, we conclude that the position of this active region strongly influences the directionality and efficiency of the emission. Our results will help to improve the design of nanowire based LEDs and single photon sources.

  6. 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 i...

  7. 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.

  8. Directional flow induced by synchronized longitudinal and zeta-potential controlling AC-electrical fields

    NARCIS (Netherlands)

    Wouden, van der E.J.; Hermes, D.C.; Gardeniers, J.G.E.; Berg, van den A.

    2006-01-01

    Electroosmotic flow (EOF) in a microchannel can be controlled by electronic control of the surface charge using an electrode embedded in the wall of the channel. By setting a voltage to the electrode, the zeta-potential at the wall can be changed locally. Thus, the electrode acts as a "gate" for liq

  9. 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...

  10. An estimation method of the direct benefit of a waterlogging control project applicable to the changing environment

    Science.gov (United States)

    Zengmei, L.; Guanghua, Q.; Zishen, C.

    2015-05-01

    The direct benefit of a waterlogging control project is reflected by the reduction or avoidance of waterlogging loss. Before and after the construction of a waterlogging control project, the disaster-inducing environment in the waterlogging-prone zone is generally different. In addition, the category, quantity and spatial distribution of the disaster-bearing bodies are also changed more or less. Therefore, under the changing environment, the direct benefit of a waterlogging control project should be the reduction of waterlogging losses compared to conditions with no control project. Moreover, the waterlogging losses with or without the project should be the mathematical expectations of the waterlogging losses when rainstorms of all frequencies meet various water levels in the drainage-accepting zone. So an estimation model of the direct benefit of waterlogging control is proposed. Firstly, on the basis of a Copula function, the joint distribution of the rainstorms and the water levels are established, so as to obtain their joint probability density function. Secondly, according to the two-dimensional joint probability density distribution, the dimensional domain of integration is determined, which is then divided into small domains so as to calculate the probability for each of the small domains and the difference between the average waterlogging loss with and without a waterlogging control project, called the regional benefit of waterlogging control project, under the condition that rainstorms in the waterlogging-prone zone meet the water level in the drainage-accepting zone. Finally, it calculates the weighted mean of the project benefit of all small domains, with probability as the weight, and gets the benefit of the waterlogging control project. Taking the estimation of benefit of a waterlogging control project in Yangshan County, Guangdong Province, as an example, the paper briefly explains the procedures in waterlogging control project benefit estimation. The

  11. 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.

  12. 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.

  13. Transcranial direct current stimulation in refractory continuous spikes and waves during slow sleep: a controlled study

    DEFF Research Database (Denmark)

    Varga, Edina T; Terney, Daniella; Atkins, Mary D

    2011-01-01

    Cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability. The purpose of the study was to investigate whether cathodal tDCS could interrupt the continuous epileptiform activity. Five patients with focal, refractory continuous spikes and waves during slow sleep were ...

  14. Direct control of the small-scale energy balance in two-dimensional fluid dynamics

    NARCIS (Netherlands)

    Frank, Jason; Leimkuhler, Benedict; Myerscough, Keith W.

    2015-01-01

    We explore the direct modification of the pseudo-spectral truncation of two-dimensional, 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 sta

  15. Goal-directed action control in children with autism spectrum disorders

    NARCIS (Netherlands)

    Geurts, H.M.; de Wit, S.

    2014-01-01

    Repetitive behavior is a key characteristic of autism spectrum disorders. Our aim was to investigate the hypothesis that this abnormal behavioral repetition results from a tendency to over-rely on habits at the expense of flexible, goal-directed action. Twenty-four children with autism spectrum diso

  16. Multicore Based Open Loop Motor Controller Embedded System for Permanent Magnet Direct Current Motor

    Directory of Open Access Journals (Sweden)

    K. Baskaran

    2012-01-01

    Full Text Available Problem statement: In an advanced electronics world most of the applications are developed by microcontroller based embedded system. Approach: Multicore processor based motor controller was presented to improve the processing speed of the controller and improve the efficiency of the motor by maintaining constant speed. It was based on the combination of Cortex processor (Software core and Field Programmable Gate Arrays (FPGA, Hardware core. These multicore combination were help to design efficient low power motor controller. Results: A functional design of cortex processor and FPGA in this system was completed by using Actel libero IDE and IAR embedded IDE software PWM signal was generated by the proposed processor to control the motor driver circuit. All the function modules were programmed by Very-High-Speed Integrated Circuit Hardware Description Language (VHDL. The advantage of the proposed system was optimized operational performance and low power utility. Multicore processor was used to improve the speed of execution and optimize the performance of the controller. Conclusion: Without having the architectural concept of any motor we can control it by using this method.This is an low cost low power controller and easy to use. The simulation and experiment results verified its validity.

  17. 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.

  18. 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.

  19. Control of homogeneous charge compression ignition combustion in a two-cylinder gasoline direct injection engine with negative valve overlap

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi; WANG Jianxin; SHUAI Shijin; MA Qingjun; TIAN Guohong

    2007-01-01

    Homogeneous charge compression ignition(HCCI) has challenges in ignition timing control,combustion rate control,and operating range extension.In this paper,HCCI combustion was studied in a two-cylinder gasoline direct injection (GDI) engine with negative valve overlap (NVO).A two-stage gasoline direct injection strategy combined with negative valve overlap was used to control mixture formation and combustion.The gasoline engine could be operated in HCCI combustion mode at a speed range of 800-2 200 r/min and load,indicated mean effective pressure (IMEP) range of 0.1-0.53 MPa.The engine fuel consumption 4× 10-5 without soot emission.The effect of different injection strategies on HCCI combustion was studied.The experimental results indicated that the coefficient of variation of the engine cycle decreased by using NVO with two-stage direct injection;the ignition timing and combustion rate could be controlled;and the operational range of HCCI combustion could be extended.

  20. 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.

  1. Manipulation based on sensor-directed control: An integrated end effector and touch sensing system

    Science.gov (United States)

    Hill, J. W.; Sword, A. J.

    1973-01-01

    A hand/touch sensing system is described that, when mounted on a position-controlled manipulator, greatly expands the kinds of automated manipulation tasks that can be undertaken. Because of the variety of coordinate conversions, control equations, and completion criteria, control is necessarily dependent upon a small digital computer. The sensing system is designed both to be rugged and to sense the necessary touch and force information required to execute a wide range of manipulation tasks. The system consists of a six-axis wrist sensor, external touch sensors, and a pair of matrix jaw sensors. Details of the construction of the particular sensors, the integration of the end effector into the sensor system, and the control algorithms for using the sensor outputs to perform manipulation tasks automatically are discussed.

  2. Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls

    Science.gov (United States)

    Kallenbach, Cynthia M.; Frey, Serita D.; Grandy, A. Stuart

    2016-11-01

    Soil organic matter (SOM) and the carbon and nutrients therein drive fundamental submicron- to global-scale biogeochemical processes and influence carbon-climate feedbacks. Consensus is emerging that microbial materials are an important constituent of stable SOM, and new conceptual and quantitative SOM models are rapidly incorporating this view. However, direct evidence demonstrating that microbial residues account for the chemistry, stability and abundance of SOM is still lacking. Further, emerging models emphasize the stabilization of microbial-derived SOM by abiotic mechanisms, while the effects of microbial physiology on microbial residue production remain unclear. Here we provide the first direct evidence that soil microbes produce chemically diverse, stable SOM. We show that SOM accumulation is driven by distinct microbial communities more so than clay mineralogy, where microbial-derived SOM accumulation is greatest in soils with higher fungal abundances and more efficient microbial biomass production.

  3. Directional cell movements downstream of Gbx2 and Otx2 control the assembly of sensory placodes

    Directory of Open Access Journals (Sweden)

    Ben Steventon

    2016-11-01

    Full Text Available Cranial placodes contribute to sensory structures including the inner ear, the lens and olfactory epithelium and the neurons of the cranial sensory ganglia. At neurula stages, placode precursors are interspersed in the ectoderm surrounding the anterior neural plate before segregating into distinct placodes by as yet unknown mechanisms. Here, we perform live imaging to follow placode progenitors as they aggregate to form the lens and otic placodes. We find that while placode progenitors move with the same speed as their non-placodal neighbours, they exhibit increased persistence and directionality and these properties are required to assemble morphological placodes. Furthermore, we demonstrate that these factors are components of the transcriptional networks that coordinate placode cell behaviour including their directional movements. Together with previous work, our results support a dual role for Otx and Gbx transcription factors in both the early patterning of the neural plate border and the later segregation of its derivatives into distinct placodes.

  4. 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.

  5. Transcranial direct current stimulation in refractory continuous spikes and waves during slow sleep: a controlled study

    DEFF Research Database (Denmark)

    Varga, Edina T; Terney, Daniella; Atkins, Mary D;

    2011-01-01

    Cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability. The purpose of the study was to investigate whether cathodal tDCS could interrupt the continuous epileptiform activity. Five patients with focal, refractory continuous spikes and waves during slow sleep were...... recruited. Cathodal tDCS and sham stimulation were applied to the epileptic focus, before sleep (1 mA; 20 min). Cathodal tDCS did not reduce the spike-index in any of the patients....

  6. Biological Inspired Direct Adaptive Guidance and Control for Autonomous Flight Systems

    Science.gov (United States)

    2007-11-02

    improvements for existing algorithms. " Continue the phase I effort to develop and demonstrate an architecture for direct adaptive guidance including...e.g., 1 x I x 2 cm) autonomous, cooperative agents from the point of view of power (e.g., 1 mW for a year), bionics , and navigation/guidance. Although...guidance solution (such as PN) to correct for evasive target maneuvering. One such architecture that appears to be suitable for surmounting this difficulty

  7. Model-based predictive direct power control of brushless doubly fed reluctance generator for wind power applications

    Directory of Open Access Journals (Sweden)

    Maryam Moazen

    2016-09-01

    Full Text Available In this paper, a predictive direct power control (PDPC method for the brushless doubly fed reluctance generator (BDFRG is proposed. Firstly, the BDFRG active and reactive power equations are derived and then the active and reactive power variations have been predicted within a fixed sampling period. The predicted power variations are used to calculate the required voltage of the secondary winding so that the power errors at the end of the following sampling period are eliminated. Switching pulses are produced using space vector pulse width modulation (SVPWM approach which causes to a fixed switching frequency. The BDFRG model and the proposed control method are simulated in MATLAB/Simulink software. Simulation results indicate the good performance of the control system in tracking of the active and reactive power references in both power step and speed variation conditions. In addition, fast dynamic response and lower output power ripple are other advantages of this control method.

  8. A direct CO2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum

    Directory of Open Access Journals (Sweden)

    Laura Sordo

    2016-09-01

    Full Text Available Most ocean acidification (OA experimental systems rely on pH as an indirect way to control CO2. However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and pCO2. Here we describe a system in which the target pCO2 is controlled via direct analysis of pCO2 in seawater. This direct type of control accommodates potential temperature and salinity shifts, as the target variable is directly measured instead of being estimated. Water in a header tank is permanently re-circulated through an air-water equilibrator. The equilibrated air is then routed to an infrared gas analyzer (IRGA that measures pCO2 and conveys this value to a Proportional-Integral-Derivative (PID controller. The controller commands a solenoid valve that opens and closes the CO2 flush that is bubbled into the header tank. This low-cost control system allows the maintenance of stabilized levels of pCO2 for extended periods of time ensuring accurate experimental conditions. This system was used to study the long term effect of OA on the coralline red algae Phymatolithon lusitanicum. We found that after 11 months of high CO2 exposure, photosynthesis increased with CO2 as opposed to respiration, which was positively affected by temperature. Results showed that this system is adequate to run long-term OA experiments and can be easily adapted to test other relevant variables simultaneously with CO2, such as temperature, irradiance and nutrients.

  9. A direct CO2 control system for ocean acidification experiments: testing effects on the coralline red algae Phymatolithon lusitanicum

    Science.gov (United States)

    Santos, Rui; Reis, Joao; Shulika, Alona

    2016-01-01

    Most ocean acidification (OA) experimental systems rely on pH as an indirect way to control CO2. However, accurate pH measurements are difficult to obtain and shifts in temperature and/or salinity alter the relationship between pH and pCO2. Here we describe a system in which the target pCO2 is controlled via direct analysis of pCO2 in seawater. This direct type of control accommodates potential temperature and salinity shifts, as the target variable is directly measured instead of being estimated. Water in a header tank is permanently re-circulated through an air-water equilibrator. The equilibrated air is then routed to an infrared gas analyzer (IRGA) that measures pCO2 and conveys this value to a Proportional-Integral-Derivative (PID) controller. The controller commands a solenoid valve that opens and closes the CO2 flush that is bubbled into the header tank. This low-cost control system allows the maintenance of stabilized levels of pCO2 for extended periods of time ensuring accurate experimental conditions. This system was used to study the long term effect of OA on the coralline red algae Phymatolithon lusitanicum. We found that after 11 months of high CO2 exposure, photosynthesis increased with CO2 as opposed to respiration, which was positively affected by temperature. Results showed that this system is adequate to run long-term OA experiments and can be easily adapted to test other relevant variables simultaneously with CO2, such as temperature, irradiance and nutrients. PMID:27703853

  10. 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.

  11. Development of swashplateless helicopter blade pitch control system using the limited angle direct-drive motor (LADDM)

    Institute of Scientific and Technical Information of China (English)

    Wang Jian; Wang Haowen; Wu Chao

    2015-01-01

    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 reduc-tion 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.

  12. 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...... voltage-current model with PI compensator for low-speed operations. As speed increases, the observer switches gradually to a PI compensated closed-loop voltage model, which is solely used at high speeds. High-frequency rotating-voltage injection with a single D-module bandpass vector filter and a phase...

  13. [The main directions of improving the system of state accounting and control of radioactive substances and radioactive waste products].

    Science.gov (United States)

    2012-01-01

    This paper describes a modification of the basic directions of state accounting and control of radioactive substances and radioactive waste products, whose implementation will significantly improve the efficiency of its operation at the regional level. Selected areas are designed to improve accounting and control system for the submission of the enterprises established by the reporting forms, the quality of the information contained in them, as well as structures of information and process for collecting, analyzing and data processing concerning radioactive substances and waste products.

  14. 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.

  15. 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.

  16. Goal-directed memory: the role of cognitive control in older adults' emotional memory.

    Science.gov (United States)

    Mather, Mara; Knight, Marisa

    2005-12-01

    The present study revealed that older adults recruit cognitive control processes to strengthen positive and diminish negative information in memory. In Experiment 1, older adults engaged in more elaborative processing when retrieving positive memories than they did when retrieving negative memories. In Experiment 2, older adults who did well on tasks involving cognitive control were more likely than those doing poorly to favor positive pictures in memory. In Experiment 3, older adults who were distracted during memory encoding no longer favored positive over negative pictures in their later recall, revealing that older adults use cognitive resources to implement emotional goals during encoding. In contrast, younger adults showed no signs of using cognitive control to make their memories more positive, indicating that, for them, emotion regulation goals are not chronically activated.

  17. Neural substrates of visual spatial coding and visual feedback control for hand movements in allocentric and target-directed tasks

    Directory of Open Access Journals (Sweden)

    Lore eThaler

    2011-08-01

    Full Text Available Neuropsychological evidence suggests that different brain areas may be involved in movements that are directed at visual targets (e.g. pointing or reaching, and movements that are based on allocentric visual information (e.g. drawing or copying. Here we used fMRI to investigate the neural correlates of these two types of movements in healthy volunteers. Subjects (n=14 performed right-hand movements in either a target-directed task (moving a cursor to a target dot or an allocentric task (moving a cursor to reproduce the distance and direction between two distal target dots with or without visual feedback about their hand movement. Movements were monitored with an MR compatible touch panel. A whole-brain analysis revealed that movements in allocentric conditions led to an increase in activity in the fundus of the left intraparietal sulcus (IPS, in posterior IPS, in bilateral dorsal premotor cortex (PMd, and in the Lateral Occipital Complex (LOC. Visual feedback in both target-directed and allocentric conditions led to an increase in activity in area MT+, superior parietal occipital cortex (SPOC and posterior IPS (all bilateral. In addition, we found that visual feedback affected brain activity differently in target-directed as compared to allocentric conditions, in particular in pre-supplementary motor area, PMd, IPS and parieto-occipital cortex. Our results, in combination with previous findings, suggest that the LOC is essential for allocentric visual coding and that SPOC is involved in visual feedback control. The differences in brain activity between target-directed and allocentric visual feedback conditions may be related to behavioral differences in visual feedback control. Our results advance the understanding of the visual coordinate frame used by the LOC. In addition, because of the nature of the allocentric task, our results have relevance for the understanding of neural substrates of magnitude estimation and vector-coding of movements.

  18. Thermo-optic control of dielectric-loaded plasmonic Mach-Zehnder interferometers and directional coupler switches

    DEFF Research Database (Denmark)

    Gosciniak, J.; Markey, L.; Dereux, A.

    2012-01-01

    We report detailed experimental studies of compact fiber-coupled dielectric-loaded plasmonic waveguide components-Mach-Zehnder interferometers (MZIs) and directional couplers (DCs)-whose operation at telecom wavelengths is controlled via the thermo-optic effect by electrically heating the gold st......, and wavelength dependent low power (similar to 0.92 mW) rerouting is achieved with DC switches. Furthermore, simulations were performed to confirm the switching characteristics of the components....

  19. 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.

  20. A general modelling and control algorithm of a three-phase multilevel diode clamped inverter by means of a direct space vector control

    Science.gov (United States)

    Bouhali, O.; Francois, B.; Berkouk, E. M.; Saudemont, C.

    2005-07-01

    This paper presents a simple and general direct modulation strategy that enables to copy directly modulated waveforms onto output voltages of a multilevel three-phase Diode Clamped Inverter (DCI). A general modelling of this converter is presented. A space vector scheme is developed without using Park transforms. Based on this algorithm, the location of the reference voltage vector is determined and the voltage vectors for the modulation are deduced. Simultaneously, their durations are calculated. The proposed algorithm is general and can be directly applied to a (n+1) levels inverter independently on its topology (Diode Clamped Inverter, Neutral Point Clamped, Flying Capacitor Inverter...). To verify this algorithm, both control algorithms of a 5-level DCI and a 11-level DCI are considered and simulation results are given.

  1. Sequential interactions with Sec23 control the direction of vesicle traffic

    OpenAIRE

    LORD, christopher; Bhandari, Deepali; Menon, Shekar; Ghassemian, Majid; Nycz, Deborah; Hay, Jesse; Ghosh, Pradipta; Ferro-Novick, Susan

    2011-01-01

    How the directionality of vesicle traffic is achieved remains an important unanswered question in cell biology. The Sec23p/Sec24p coat complex sorts the fusion machinery (SNAREs) into vesicles as they bud from the endoplasmic reticulum. Vesicle tethering to the Golgi begins when the tethering factor TRAPPI binds to Sec23p. Where the coat is released and how this event relates to membrane fusion is unknown. Here we use a yeast transport assay to demonstrate that an ER-derived vesicle retains i...

  2. Visual Illusions and the Control of Ball Placement in Goal-Directed Hitting

    Science.gov (United States)

    Caljouw, Simone R.; Van der Kamp, John; Savelsbergh, Geert J. P.

    2010-01-01

    When hitting, kicking, or throwing balls at targets, online control in the target area is impossible. We assumed this lack of late corrections in the target area would induce an effect of a single-winged Muller-Lyer illusion on ball placement. After extensive practice in hitting balls to different landing locations, participants (N = 9) had to hit…

  3. Visual Illusions and the Control of Ball Placement in Goal-Directed Hitting

    NARCIS (Netherlands)

    Caljouw, Simone R.; Van der Kamp, John; Savelsbergh, Geert J. P.

    2010-01-01

    When hitting, kicking, or throwing balls at targets, online control in the target area is impossible We assumed this lack of late corrections in the target area would induce an effect of a single-winged Muller-Lyer illusion on ball placement After extensive practice in hitting balls to different lan

  4. 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…

  5. Ancillary Frequency Control of Direct Drive Full-Scale Converter Based Wind Power Plants

    DEFF Research Database (Denmark)

    Hu, Weihao; Su, Chi; Fang, Jiakun;

    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 ...

  6. The direction of effects between perceived parental behavioral control and psychological control and adolescents' self-reported GAD and SAD symptoms

    OpenAIRE

    Wijsbroek, Saskia A. M.; Hale III, William W.; Raaijmakers, Quinten A. W.; Meeus, Wim H. J.

    2011-01-01

    Abstract This study examined the direction of effects and age and sex differences between adolescents? perceptions of parental behavioral and psychological control and adolescents? self-reports of generalized anxiety disorder (GAD) and separation anxiety disorder (SAD) symptoms. The study focused on 1,313 Dutch adolescents (early-to-middle cohort n = 923, 70.3%; middle-to-late cohort n = 390, 29.7%) from the general population. A multi-group, structural equation model was employed ...

  7. Sequential interactions with Sec23 control the direction of vesicle traffic.

    Science.gov (United States)

    Lord, Christopher; Bhandari, Deepali; Menon, Shekar; Ghassemian, Majid; Nycz, Deborah; Hay, Jesse; Ghosh, Pradipta; Ferro-Novick, Susan

    2011-05-12

    How the directionality of vesicle traffic is achieved remains an important unanswered question in cell biology. The Sec23p/Sec24p coat complex sorts the fusion machinery (SNAREs) into vesicles as they bud from the endoplasmic reticulum (ER). Vesicle tethering to the Golgi begins when the tethering factor TRAPPI binds to Sec23p. Where the coat is released and how this event relates to membrane fusion is unknown. Here we use a yeast transport assay to demonstrate that an ER-derived vesicle retains its coat until it reaches the Golgi. A Golgi-associated kinase, Hrr25p (CK1δ orthologue), then phosphorylates the Sec23p/Sec24p complex. Coat phosphorylation and dephosphorylation are needed for vesicle fusion and budding, respectively. Additionally, we show that Sec23p interacts in a sequential manner with different binding partners, including TRAPPI and Hrr25p, to ensure the directionality of ER-Golgi traffic and prevent the back-fusion of a COPII vesicle with the ER. These events are conserved in mammalian cells.

  8. 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

    2008-06-11

    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 Si(3)N(4) and W/Si(3)N(4) 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.

  9. Comprehensive strategies for the prevention and control of diabetes and cardiovascular diseases in Africa: future directions.

    Science.gov (United States)

    Muna, Walinjom F T

    2013-01-01

    The countries of the Sub Saharan African region have insufficient resources and healthcare systems that are poorly adapted to cope with the longstanding burden associated with communicable diseases and the ongoing HIV/AIDS pandemic. In addition, the rising burden of non-communicable diseases, including diabetes, cardiovascular diseases, and their risk factors, poses additional challenges. These countries need to urgently develop strategies to address these challenges of disease prevention and control. These strategies will require a new vision and more relevant and 'suitable' vocabulary in dealing with healthcare design, planning and implementation (using a cross-sectorial approach). Lessons learnt from the past (e.g. primary health care) in sub-Saharan Africa and other regions of the world may equally prove useful in developing strategies for the prevention and control of non-communicable diseases. Any potential strategy must emphasize the crucial role of economic, social, and environmental health determinants as well as the use of appropriate health technology.

  10. Direct optical activation of skeletal muscle fibres efficiently controls muscle contraction and attenuates denervation atrophy.

    Science.gov (United States)

    Magown, Philippe; Shettar, Basavaraj; Zhang, Ying; Rafuse, Victor F

    2015-10-13

    Neural prostheses can restore meaningful function to paralysed muscles by electrically stimulating innervating motor axons, but fail when muscles are completely denervated, as seen in amyotrophic lateral sclerosis, or after a peripheral nerve or spinal cord injury. Here we show that channelrhodopsin-2 is expressed within the sarcolemma and T-tubules of skeletal muscle fibres in transgenic mice. This expression pattern allows for optical control of muscle contraction with comparable forces to nerve stimulation. Force can be controlled by varying light pulse intensity, duration or frequency. Light-stimulated muscle fibres depolarize proportionally to light intensity and duration. Denervated triceps surae muscles transcutaneously stimulated optically on a daily basis for 10 days show a significant attenuation in atrophy resulting in significantly greater contractile forces compared with chronically denervated muscles. Together, this study shows that channelrhodopsin-2/H134R can be used to restore function to permanently denervated muscles and reduce pathophysiological changes associated with denervation pathologies.

  11. New directions for understanding neural control in swallowing: the potential and promise of motor learning.

    Science.gov (United States)

    Humbert, Ianessa A; German, Rebecca Z

    2013-03-01

    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 oropharyngeal swallowing and to review the principles of motor learning based on limb movements as a model system. We compare this literature on limb motor learning to what is known about oropharyngeal function as a first step toward suggesting the use of motor learning principles in swallowing research.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    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....... Some health care workers, community leaders and drug distributors were generally positive about the intervention, emphasizing that the drugs were welcome. Other stakeholders, including the drug-receiving population, reported facing a number of dilemmas of uncertainty, authority and exclusion pertaining...

  13. Advanced Control Filtering and Prediction for Phased Arrays in Directed Energy Systems

    Science.gov (United States)

    2014-07-31

    SIMULINK model for prediction and feedback control of a phase ramp. Mirror represented by integrator with sample time tsim. The model shown has a...and simulating the closed-loop system in SIMULINK . Approved for public release; distribution unlimited 3 4.0 RESULTS AND DISCUSSION 4.1...although this measurement probably is not necessary. 4.2 Simulation Model There are three differences between the current SIMULINK model and the

  14. 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.

  15. Immunity induced by a broad class of inorganic crystalline materials is directly controlled by their chemistry.

    Science.gov (United States)

    Williams, Gareth R; Fierens, Kaat; Preston, Stephen G; Lunn, Daniel; Rysnik, Oliwia; De Prijck, Sofie; Kool, Mirjam; Buckley, Hannah C; Lambrecht, Bart N; O'Hare, Dermot; Austyn, Jonathan M

    2014-06-02

    There 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 physicochemical properties in a highly predictable manner. We show that structurally and chemically homogeneous layered double hydroxides (LDHs) can elicit diverse human dendritic cell responses in vitro. Using a systems vaccinology approach, we find that every measured response can be modeled using a subset of just three physical and chemical properties for all compounds tested. This correlation can be reduced to a simple linear equation that enables the immunological responses stimulated by newly synthesized LDHs to be predicted in advance from these three parameters alone. We also show that mouse antigen-specific antibody responses in vivo and human macrophage responses in vitro are controlled by the same properties, suggesting they may control diverse responses at both individual component and global levels of immunity. This study demonstrates that immunity can be determined purely by chemistry and opens the possibility of rational manipulation of immunity for therapeutic purposes.

  16. 'PhysioDirect' telephone assessment and advice services for physiotherapy: protocol for a pragmatic randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Hopper Cherida

    2009-08-01

    the service, the acceptability of PhysioDirect to patients and staff, and ways in which the service could be improved. Discussion It is still relatively unusual to evaluate new forms of service delivery using randomised controlled trials. By combining rigorous trial methods with economic analysis of cost-effectiveness and qualitative research this study will provide robust evidence to inform decisions about the widespread introduction of PhysioDirect services. Trial registration Current Controlled Trials ISRCTN55666618

  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. The dynamics of individual nucleosomes controls the chromatin condensation pathway: direct AFM visualization of variant chromatin

    CERN Document Server

    Montel, Fabien; Castelnovo, Martin; Bednar, Jan; Dimitrov, Stefan; Angelov, Dimitar; Faivre-Moskalenko, Cendrine

    2009-01-01

    Chromatin organization and dynamics is studied in this work at scales ranging from single nucleosome to nucleosomal array by using a unique combination of biochemical assays, single molecule imaging technique and numerical modeling. We demonstrate that a subtle modification in the nucleosome structure induced by the histone variant H2A.Bbd drastically modifies the higher order organization of the nucleosomal arrays. Importantly, as directly visualized by AFM, conventional H2A nucleosomal arrays exhibit specific local organization, in contrast to H2A.Bbd arrays, which show ?beads on a string? structure. The combination of systematic image analysis and theoretical modeling allows a quantitative description relating the observed gross structural changes of the arrays to their local organization. Our results strongly suggest that higher-order organization of H1-free nucleosomal arrays is mainly determined by the fluctuation properties of individual nucleosomes. Moreover, numerical simulations suggest the existenc...

  19. 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.

  20. Postural trials: expertise in rhythmic gymnastics increases control in lateral directions.

    Science.gov (United States)

    Calavalle, A R; Sisti, D; Rocchi, M B L; Panebianco, R; Del Sal, M; Stocchi, V

    2008-11-01

    The first aim of this paper was to investigate if expertise in rhythmic gymnastics influences postural performance even in an easy non-specific task such as bipedal posture. Rhythmic gymnastics is a unique female sport which encompasses aspects of both artistic gymnastics and ballet and includes the use of a small apparatus (rope, hoop, ball, clubs and ribbon). Most previous studies have shown that expertise achieved by artistic gymnasts and dancers improves postural steadiness only in the situations for which those athletes are trained. Literature has not yet compared rhythmic gymnasts to other athletes in terms of their postural strategies. Hence, the study presented herein tested a group of high level rhythmic gymnasts and a group of female university students, trained in other sports, in the bipedal posture under eyes open and closed conditions. A force platform was used to record body sway. (1) Distance from the centre of sway, (2) lateral and (3) antero-posterior displacements were analyzed in time and frequency domains. Comparing the two groups, it was found that rhythmic gymnasts had better strategies than students in simple postural tasks, especially in lateral directions and in the period from 0.05 to 2 s. The most interesting finding in this study is that rhythmic gymnastics training seems to have a direct effect on the ability to maintain bipedal posture, which may confirm the "transfer" hypothesis of rhythmic gymnastics expertise to bipedal postural sway, especially in medio-lateral displacements. This finding has never been reported in previous studies on artistic gymnasts and ballet dancers. Furthermore, the present study confirmed the visual dependence of all the athletes, irrespective of their disciplines, in their postural trials.

  1. 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.

  2. A synthesis pattern of acoustic field produced by phased array based on the direct weighting of the controlled acoustic pressure

    Institute of Scientific and Technical Information of China (English)

    HU Jiwen; QIAN Shengyou; DING Yajun

    2012-01-01

    To optimize the acoustic field produced by phased array effectively and quickly, the pseudo-inverse method proposed previously is simplified. An approximate weight formula of sound pressure using a method of compensation to the amplitude and phase of the controlled sound pressure was presented. A multiple-focus field patterns based on the pseudo-inverse matrix algorithm can be obtained by presetting the value of the controlled sound pressure. A phased array comprised of 16 x 16 square elements is used for numerical simulation. The results show that the acoustic energy can be effectively deposited at the desired points, and the acoustic field can be synthesized quickly using the direct weight formula of the sound pressure. This study may offer an effective way for controlling the distribution of acoustic field in ultrasound hyperthermia.

  3. Alternating current-generated plasma discharges for the controlled direct current charging of ferroelectrets

    Science.gov (United States)

    Cury Basso, Heitor; Monteiro, José Roberto B. de A.; Baladelli Mazulquim, Daniel; Teixeira de Paula, Geyverson; Gonçalves Neto, Luiz; Gerhard, Reimund

    2013-09-01

    The standard charging process for polymer ferroelectrets, e.g., from polypropylene foams or layered film systems involves the application of high DC fields either to metal electrodes or via a corona discharge. In this often-used process, the DC field triggers the internal breakdown and limits the final charge densities inside the ferroelectret cavities and, thus, the final polarization. Here, an AC + DC charging procedure is proposed and demonstrated in which a high-voltage high-frequency (HV-HF) wave train is applied together with a DC poling voltage. Thus, the internal dielectric-barrier discharges in the ferroelectret cavities are induced by the HV-HF wave train, while the final charge and polarization level is controlled separately through the applied DC voltage. In the new process, the frequency and the amplitude of the HV-HF wave train must be kept within critical boundaries that are closely related to the characteristics of the respective ferroelectrets. The charging method has been tested and investigated on a fluoropolymer-film system with a single well-defined cylindrical cavity. It is found that the internal electrical polarization of the cavity can be easily controlled and increases linearly with the applied DC voltage up to the breakdown voltage of the cavity. In the standard charging method, however, the DC voltage would have to be chosen above the respective breakdown voltage. With the new method, control of the HV-HF wave-train duration prevents a plasma-induced deterioration of the polymer surfaces inside the cavities. It is observed that the frequency of the HV-HF wave train during ferroelectret charging and the temperature applied during poling of ferroelectrics serve an analogous purpose. The analogy and the similarities between the proposed ferroelectret charging method and the poling of ferroelectric materials or dipole electrets at elevated temperatures with subsequent cooling under field are discussed.

  4. Direct plantlet inoculation with soil or insect-associated fungi may control cabbage root fly maggots.

    Science.gov (United States)

    Razinger, Jaka; Lutz, Matthias; Schroers, Hans-Josef; Palmisano, Marilena; Wohler, Christian; Urek, Gregor; Grunder, Jürg

    2014-07-01

    A potential Delia radicum biological control strategy involving cauliflower plantlet inoculation with various fungi was investigated in a series of laboratory and glasshouse experiments. In addition to entomopathogenic fungi, fungi with a high rhizosphere competence and fungi with the ability to survive as saprotrophs in soil were tested. The following fungal species were evaluated in the experiments: Trichoderma atroviride, T. koningiopsis, T. gamsii, Beauveria bassiana, Metharhizium anisopliae, M. brunneum and Clonostachys solani. A commercial carbosulfan-based insecticide was used as a positive control. Additionally, two commercial products, one based on B. bassiana (Naturalis) and one on Bacillus thuringiensis (Delfin) were used as reference biocontrol agents. The aims were (i) to assess the pathogenicity of the selected fungal isolates to Delia radicum, (ii) to evaluate the fungal isolates' rhizosphere competence, with the emphasis on the persistence of the original inoculum on the growing roots, (iii) to assess possible endophytic plant tissue colonization, and (iv) to evaluate potential plant growth stimulating effects of the added inoculi. Significant pathogenicity of tested fungi against Delia radicum was confirmed in in vitro and glasshouse experiments. All tested fungi persisted on cauliflower rhizoplane. More importantly, the added fungi were found on thoroughly washed roots outside the original point of inoculation. This provided us with evidence that our tested fungi could be transferred via or grow with the elongating roots. In addition to colonizing the rhizoplane, some fungi were found inside the plant root or stem tissue, thus exhibiting endophytic characteristics. The importance of fungal ecology as a criterion in appropriate biological control agent selection is discussed.

  5. Formation and control of stoichiometric hafnium nitride thin films by direct sputtering of hafnium nitride target

    CERN Document Server

    Gotoh, Y; Ishikawa, J; Liao, M Y

    2003-01-01

    Hafnium nitride thin films were prepared by radio-frequency sputter deposition with a hafnium nitride target. Deposition was performed with various rf powers, argon pressures, and substrate temperatures, in order to investigate the influences of these parameters on the film properties, particularly the nitrogen composition. It was found that stoichiometric hafnium nitride films were formed at an argon gas pressure of less than 2 Pa, irrespective of the other deposition parameters within the range investigated. Maintaining the nitrogen composition almost stoichiometric, orientation, stress, and electrical resistivity of the films could be controlled with deposition parameters. (author)

  6. A New Fixed Switching Frequency Direct Torque Controlled PMSM Drives with Low Ripple in Flux and Torque

    Directory of Open Access Journals (Sweden)

    Tole Sutikno

    2011-11-01

    Full Text Available Direct Torque Control (DTC has gained popularity for development of advanced motor control due to its simplicity and offers fast instantaneous torque and flux controls. However, the conventional DTC which is based on hysteresis controller has major drawbacks, namely high torque ripple and variable inverter switching frequency. This paper presents an improved switching strategy for reducing flux and torque ripples in DTC of PMSM drives; wherein the torque hysteresis controller and the look-up table used in the conventional DTC are replaced with a constant frequency torque controller (CFTC and an optimized look-up table, respectively. It can be shown that a constant switching frequency is established due to the use of the CFTC while the reduction of torque and flux ripples is achieved mainly because of the selection of optimized voltage vector (i.e. with an optimized look-up table. This paper also will explain the construction of DTC schemes implemented using MATLAB-Simulink blocks. Simulation results were shown that a significant reduction of flux and torque ripples which is about 90% can be achieved through the proposed DTC scheme.

  7. 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......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...

  8. BUNDLE: A Novel Furnace for Performing Controlled Directional Solidification Experiments in a Microgravity Environment

    Science.gov (United States)

    Carrasquillo, Edgar J.; Griffin, Mark R.; Hammond, Monica S.; Johnson, Martin L.; Grugel, R. N.

    2000-01-01

    NASA Marshall Space Flight Center has developed a novel directional solidification furnace prototype for processing metals and alloys experiments in a microgravity environment. The BUNDLE (Bridgman Unidirectional Dendrite in Liquid Experiment) furnace is intended to accommodate the science requirements of Flight Definition Principle Investigators studying cellular/dendritic growth in aluminum and lead alloys at processing temperatures up to 1200 C. The furnace implements a number of innovative features to achieve high thermal gradients and quench rates in a low-power, light-weight design. These include a pyrolytic boron nitride/graphite composite heating element surrounded by layers of self-supporting refractory metal shielding, and a graphite fiber enhanced cold zone allowing high levels of heat extraction from the sample crucible. Novel to the BUNDLE design is an in-situ helium gas quench capability that ensures rapid freezing of the solidifying region (mushy zone) of the metal sample within the furnace without sample disturbance prior to quenching; this is a stringent requirement for subsequent analysis and understanding of microstructural development. The experiment hardware concept features multiple furnaces that may be "bundled" together so many samples, currently up to eight, can be processed at one time. The design of BUNDLE is flexible enough to be implemented on the Shuttle and Space Station in a number of locations (SpaceHab, Express Rack, MPESS, ISPR, etc). BUNDLE prototype furnaces have directionally solidified and quenched 1cm diameter lead - 5.8 weight percent antimony and aluminum - 4 weight percent copper alloys. Quenching of the mushy zone, as recorded by in-situ thermocouples, occurred on the order of 0.5 seconds or less, a rate within the PI's requirements. Subsequent metallographic examination revealed the solidified microstructure to be, as expected, unidirectional. Both the dendrite tips and the eutectic reaction were planar in nature

  9. BUNDLE - A Novel Furnace for Performing Controlled Directional Solidification Experiments in a Microgravity Environment

    Science.gov (United States)

    Carrasquillo, Edgar J.; Griffin, Mark R.; Hammond, Monica S.; Johnson, Martin L.; Grugel, R. N.

    2001-01-01

    NASA Marshall Space Flight Center has developed a novel directional solidification furnace prototype for processing metals and alloys experiments in a microgravity environment. The BUNDLE (Bridgman Unidirectional Dendrite in Liquid Experiment) furnace is intended to accommodate the science requirements of Flight Definition Principle Investigators studying cellular/dendritic growth in aluminum and lead alloys at processing temperatures up to 1200 C. The furnace implements a number of innovative features to achieve high thermal gradients and quench rates in a low-power, light-weight design. These include a pyrolytic boron nitride/graphite composite heating element surrounded by layers of self-supporting refractory metal shielding, and a graphite fiber enhanced cold zone allowing high levels of heat extraction from the sample crucible. Novel to the BUNDLE design is an in-situ helium gas quench capability that ensures rapid freezing of the solidifying region (mushy zone) of the metal sample within the furnace without sample disturbance prior to quenching; this is a stringent requirement for subsequent analysis and understanding of microstructural development. The experiment hardware concept features multiple furnaces that may be "bundled" together so many samples, currently up to eight, can be processed at one time. The design of BUNDLE is flexible enough to be implemented on the Shuttle and Space Station in a number of locations (SpaceHab, Express Rack, MPESS, ISPR, etc). BUNDLE prototype furnaces have directionally solidified and quenched 1cm diameter lead - 5.8 weight percent antimony and aluminum - 4 weight percent copper alloys. Quenching of the mushy zone, as recorded by in-situ thermocouples, occurred on the order of 0.5 seconds or less, a rate within the PI's requirements. Subsequent metallographic examination revealed the solidified microstructure to be, as expected, unidirectional. Both the dendrite tips and the eutectic reaction were planar in nature

  10. 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.

  11. Decomposed fuzzy systems and their application in direct adaptive fuzzy control.

    Science.gov (United States)

    Hsueh, Yao-Chu; Su, Shun-Feng; Chen, Ming-Chang

    2014-10-01

    In this paper, a novel fuzzy structure termed as the decomposed fuzzy system (DFS) is proposed to act as the fuzzy approximator for adaptive fuzzy control systems. The proposed structure is to decompose each fuzzy variable into layers of fuzzy systems, and each layer is to characterize one traditional fuzzy set. Similar to forming fuzzy rules in traditional fuzzy systems, layers from different variables form the so-called component fuzzy systems. DFS is proposed to provide more adjustable parameters to facilitate possible adaptation in fuzzy rules, but without introducing a learning burden. It is because those component fuzzy systems are independent so that it can facilitate minimum distribution learning effects among component fuzzy systems. It can be seen from our experiments that even when the rule number increases, the learning time in terms of cycles is still almost constant. It can also be found that the function approximation capability and learning efficiency of the DFS are much better than that of the traditional fuzzy systems when employed in adaptive fuzzy control systems. Besides, in order to further reduce the computational burden, a simplified DFS is proposed in this paper to satisfy possible real time constraints required in many applications. From our simulation results, it can be seen that the simplified DFS can perform fairly with a more concise decomposition structure.

  12. 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

  13. Implementation of air quality control in reproductive laboratories in full compliance with the Brazilian Cells and Germinative Tissue Directive.

    Science.gov (United States)

    Esteves, Sandro C; Bento, Fabiola C

    2013-01-01

    This article describes how Androfert complied with the Brazilian Cells and Germinative Tissue Directive with regard to air quality standards and presents retrospective data of intracytoplasmic sperm injection (ICSI) outcomes performed in controlled environments. An IVF facility, composed of reproductive laboratories, operating room and embryo-transfer room, was constructed according to cleanroom standards for air particles and volatile organic compounds. A total of 2060 couples requesting IVF were treated in the cleanroom facilities, and outcome measures compared with a cohort of 255 couples treated at a conventional facility from the same practice before implementation of cleanrooms. No major fluctuations were observed in the cleanroom validation measurements over the study period. Live birth rates increased (35.6% versus 25.8%; P=0.02) and miscarriage rates decreased (28.7% versus 20.0%; P=0.04) in the first triennium after cleanroom implementation. Thereafter, the proportion of high-quality embryos steadily increased whereas pregnancy outcomes after ICSI were sustained despite the increased female age and decreased number of embryos transferred. This study demonstrates the feasibility of handling human gametes and culturing embryos in full compliance with the Brazilian directive on air quality standards and suggests that performing IVF in controlled environments may optimize its outcomes. Regulatory agencies in many countries have issued directives including specific requirements for air quality standards in embryology facilities. This article describes how we complied with the Brazilian Cells and Germinative Tissue Directive with regard to air quality standards. It also presents results of IVF cycles performed in controlled environments. An IVF facility, composed of reproductive laboratories, operating room and embryo transfer room, was constructed according to cleanroom standards for air particles and volatile organic compounds. The cleanest area was the

  14. Directed Ligand Passage Over the Surface of Diffusion-Controlled Enzymes: A Cellular Automata Model

    CERN Document Server

    Ghaemi, M; Sarbolouki, M N; Ghaemi, Mehrdad; Rezaei-Ghaleh, Nasrollah; Sarbolouki, Mohammad-Nabi

    2004-01-01

    The rate-limiting step of some enzymatic reactions is a physical step, i.e. diffusion. The efficiency of such reactions can be improved through an increase in the arrival rate of the substrate molecules, e.g. by a directed passage of substrate (ligand) to active site after its random encounter with the enzyme surface. Herein, we introduce a cellular automata model simulating the ligand passage over the protein surface to its destined active site. The system is simulated using the lattice gas automata with probabilistic transition rules. Different distributions of amino acids over the protein surface are examined. For each distribution, the hydration pattern is achieved and the mean number of iteration steps needed for the ligand to arrive at the active site calculated. Comparison of results indicates that the rate at which ligand arrives at the active site is clearly affected by the distribution of amino acids outside the active side. Such a process can facilitate the ligand diffusion towards the active site ...

  15. Progress in directed energy control of vectors for microbes and other cells

    Science.gov (United States)

    Kiel, Johnathan L.; Parker, Jill E.; Holwitt, Eric A.; Vivekananda, Jeeva; Sloan, Mark A.; Stribling, Lucille J. V.

    2004-07-01

    Biosynthetic semiconductor, diazoluminomelanin (DALM), is a polymer of tyrosine, luminol, and nitrite. DALM has a very large cross section of absorption for light from ultraviolet to radio frequencies. This polymer can be made efficiently in a genetically engineered E.coli, JM109/pIC2ORNR1.1 (ATCC# 69905). We have been pursuing ways to couple electromagnetic radiation to vectors using this polymer. DNA capture elements (DCEs; formerly aptamers) have made this possible. We incorporated DCEs into the plasmid of this E. coli to direct binding to whatever microbe or cell desired and to produce DALM attached to the plasmid DNA. Using two other vectors pSV2neoNR101 or pSV2neoNR8005 (ATCC # 69617 and 69618, respectively), both propagated in the E. coli host HB101, we have also inserted genes necessary for DALM production into animal and human cell lines (mouse monocytic leukemia: ATCC # CRL- 11771, -11772, -1173, mouse mammary adenocarcinoma: ATCC# CRL-12184, -12185; and human carcinoma of the cervix: ATCC # CRL-12510). The DCE/DALM vectors can be used to tag target cells, detectable by broad-spectrum light absorbance, luminescence, or fluorescence. DCE/DALM can further be activated with light, microwave energy, or by oxidative chemistry to kill the targeted microbes or other cells.

  16. Control of PHERES1 Imprinting in Arabidopsis by Direct Tandem Repeats

    Institute of Scientific and Technical Information of China (English)

    Corina Belle R.Villar; Aleksandra Erilova; Grigory Makarevich; Raphael Tr(o)sch; Claudia K(o)hler

    2009-01-01

    Genomic imprinting is an epigenetic phenomenon that causes monoallelic expression of specific genes dependent on the parent-of-origin.Imprinting of the Arabiclopsis gene PHERES1 requires the function of the FERTILIZATION INDEPENDENT SEED (FIS) Polycomb group complex as well as a distally located methylated region containing a tandem triple repeat sequence.In this study,we investigated the regulation of the close PHERES1 homolog PHERES2.We found that PHERES2 is also a direct target gene of the FIS Polycomb group complex,but,in contrast to PHERES1,PHERES2 is equally expressed from maternal and paternal alleles.Thus,PHERES2 is not regulated by genomic imprinting,correlating with the lack of tandem repeats at PHERES2.Eliminating tandem repeats from the PHERES1 locus abolishes PHERES1 imprinting,demonstrating that tandem repeats are essential for PHERES1 imprinting.Taking these results together,our study shows that the recently duplicated genes PHERES1 and PHERES2 are both target genes of the FIS Polycomb group complex but only PHERES1 is regulated by genomic imprinting,which is likely caused by the presence of repeat sequences in the proximity of the PHERES1 locus.

  17. Controlling the Direct Laser Acceleration Inside a Plasma Bubble Using Lasers' Polarization and Wavelength

    Science.gov (United States)

    Zhang, Xi; Khudik, Vladimir; Zgadzaj, Rafal; Bernstein, Aaron; Downer, Mike; Shvets, Gennady

    2016-10-01

    The combination of the direct laser acceleration and laser wakefield acceleration (DLA and LWFA) mechanisms has been recently proposed for increasing the total electron energy gain. Here we will report on the effects of the polarization and wavelength of the DLA pulse on the properties of the accelerated beam. Specifically, we address the moderate-power regime, where the laser powers of the leading LWFA and the trailing DLA pulses are not very much larger than the critical power. Three cases will be discussed: (a) the DLA pulse has the same wavelength and polarization as the LWFA pulse, (b) the wavelengths are the same but the polarizations are orthogonal, and (c) the wavelength of the DLA pulse is twice shorter than that of the LWFA pulse. LWFA via particle-in-cell (PIC) simulations. It is found that both (b) and (c) scenarios result in higher tolerance to pulse-delay jitter. The most promising scenario is (c) because it enables higher final electron bunch energy and charge. This work is supported by the US DOE Grant DE-SC0007889 and the AFOSR Grant FA9550-14-1-0045.

  18. Demolition technique of high thin-wall hyperbolic reinforced concrete cool tower by directional controlled blasting

    Institute of Scientific and Technical Information of China (English)

    Luo Yong; Cui Xiaorong; Lu Hua

    2008-01-01

    Based on blasting demolition of high thin-wall hyperbolic reinforced concrete cool tower,by virtue of engi-neering practice of blasting the tube concrete structures,the analysis and research were made on the mechanism of cool tower collapse through selecting blasting parameters and selecting gap form,gap size and gap angle.The cool tower was twisted,collapsed directionally and broken weU according to the design requirements.The expected results and purpo-ses of blasting were obtained with no back blow,total blasted pile approximates to 4 ~ 5 m,no occurrence of flying stones and no damage to fixed buildings and equipment,the large-sized hyperbolic thin-wall reinforced concrete cool towers are twisted during blasting and it collapses well with good breaking.The test and measurement of blasting vibra-ting velocity was carried out during blasting and the measuring results are much less than critical values specified by Safety Regulations for Blasting.The study shows that gap form,gap size and gap angle are the key factors to cool tower collapse and will give beneficial references to related theoretical study and field application.

  19. Enhanced homology-directed human genome engineering by controlled timing of CRISPR/Cas9 delivery.

    Science.gov (United States)

    Lin, Steven; Staahl, Brett T; Alla, Ravi K; Doudna, Jennifer A

    2014-12-15

    The CRISPR/Cas9 system is a robust genome editing technology that works in human cells, animals and plants based on the RNA-programmed DNA cleaving activity of the Cas9 enzyme. Building on previous work (Jinek et al., 2013), we show here that new genetic information can be introduced site-specifically and with high efficiency by homology-directed repair (HDR) of Cas9-induced site-specific double-strand DNA breaks using timed delivery of Cas9-guide RNA ribonucleoprotein (RNP) complexes. Cas9 RNP-mediated HDR in HEK293T, human primary neonatal fibroblast and human embryonic stem cells was increased dramatically relative to experiments in unsynchronized cells, with rates of HDR up to 38% observed in HEK293T cells. Sequencing of on- and potential off-target sites showed that editing occurred with high fidelity, while cell mortality was minimized. This approach provides a simple and highly effective strategy for enhancing site-specific genome engineering in both transformed and primary human cells.

  20. Inductorless bi-directional piezoelectric transformerbased converters: Design and control considerations

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh

    in one package. Moreover, a progress of increasing power capability of piezoelectric transformer’s was a step forward to overcome the limitations in the technology of the piezoelectric transformers. Operation of unidirectional topology deals with finding solutions for advance control of piezoelectric......, this brings an open area for conducting further research which has been subject of this project. The research on this type of power converters are progressive but still very new in the technology to become a successful commercial product. The unique characteristics of piezoelectric transformers i.e. low...... electromagnetic interference, compact, light, high power density and low cost allows for promising market in the near future. The piezoelectric transformer technology has the potential to be used in various applications e.g. motor driver for magnetic resonance imaging scans, the electronic ballast for fluorescent...

  1. Desing and Real-Time Analysis of a Direct Current Motor Controller

    Directory of Open Access Journals (Sweden)

    Reinier Torres Labrada

    2011-10-01

    Full Text Available The real time analysis of a DC motor controller is addressed. During the functional analysis, deadline and period of tasks were extracted to be used as parameters for Response Time Analysis (RTA. To get the Worst Case Execution Time (WCET each task is stimulated with a random input vector. A great number of computation time samples were recorded and the WCET computed using the Gumbel statistical distribution. With the WCET, deadlines and periods of the task set under analysis a RTA model is evaluated and its results discussed. By modeling the WCET using the Extreme Values Theory (EVT the need of low level analysis for software and an accurate model for hardware is avoided. The method used here is useful for soft real-time systems and could be applied to other hw/sw platforms easily.

  2. Control of Fan Blade Vibrations Using Piezoelectrics and Bi-Directional Telemetry

    Science.gov (United States)

    Provenza, Andrew J.; Morrison, Carlos R.

    2011-01-01

    A novel wireless device which transfers supply power through induction to rotating operational amplifiers and transmits low voltage AC signals to and from a rotating body by way of radio telemetry has been successfully demonstrated in the NASA Glenn Research Center (GRC) Dynamic Spin Test Facility. In the demonstration described herein, a rotating operational amplifier provides controllable AC power to a piezoelectric patch epoxied to the surface of a rotating Ti plate. The amplitude and phase of the sinusoidal voltage command signal, transmitted wirelessly to the amplifier, was tuned to completely suppress the 3rd bending resonant vibration of the plate. The plate's 3rd bending resonance was excited using rotating magnetic bearing excitation while it spun at slow speed in a vacuum chamber. A second patch on the opposite side of the plate was used as a sensor. This paper discusses the characteristics of this novel device, the details of a spin test, results from a preliminary demonstration, and future plans.

  3. Treatment of impulse control disorders in Parkinson's disease: Practical considerations and future directions.

    Science.gov (United States)

    Ramirez-Zamora, Adolfo; Gee, Lucy; Boyd, James; Biller, José

    2016-01-01

    Impulse control disorders (ICDs) including compulsive gambling, buying, sexual behaviors, and eating occur relatively frequently in Parkinson disease (PD) with at least one ICD identified in 14% of PD patients in a large, multicenter, observational study. ICDs behaviors range widely in severity but can lead to catastrophic consequences, including financial ruin, divorce, loss of employment, and increased health risks. The main risk factor for ICDs in PD is the use of Dopamine agonists (DAs) and discontinuation of the offending agent is considered first line treatment. However, many patients do not tolerate this intervention as consequence of increased motor and psychiatric disability or appearance of DA withdrawal syndrome. In this article, we review current management strategies and emerging new interventions for treatment of ICDs in PD. Pharmacological treatment should be individualized based on patient's unique neuropsychiatric profile, social support, medical comorbidities, tolerability and motor symptoms.

  4. 41 CFR 102-33.135 - Do we have to follow the direction in OMB Circular A-123, “Management Accountability and Control...

    Science.gov (United States)

    2010-07-01

    ... direction in OMB Circular A-123, âManagement Accountability and Control,â June 21, 1995, for establishing management controls for our aviation program? 102-33.135 Section 102-33.135 Public Contracts and Property... Control,” June 21, 1995, for establishing management controls for our aviation program? Yes, you...

  5. Control of torque direction by spinal pathways at the cat ankle joint.

    Science.gov (United States)

    Nichols, T R; Lawrence, J H; Bonasera, S J

    1993-01-01

    To study the biomechanics of the calcaneal tendon's complex insertion onto the calcaneus, we measured torque-time trajectories exerted by the triceps surae and tibialis anterior muscles in eight unanesthetized decerebrate cats using a multi-axis force-moment sensor placed at the ankle joint. The ankle was constrained to an angle of 110 degrees plantarflexion. Muscles were activated using crossed-extension (XER), flexion (FWR), and caudal cutaneous sural nerve (SNR) reflexes. Torque contributions of other muscles activated by these reflexes were eliminated by denervation or tenotomy. In two animals, miniature pressure transducers were implanted among tendon fibers from the lateral gastrocnemius (LG) muscle that insert straight into the calcaneus or among tendon fibers from the medial gastrocnemius (MG) that cross over and insert on the lateral aspect of calcaneus. Reflexively evoked torques had the following directions: FWR, dorsiflexion and adduction; SNR, plantarflexion and abduction; and XER, plantarflexion and modest abduction or adduction. The proportion of abduction torque to plantarflexion torque was always greater for SNR than XER; this difference was about 50% of the magnitude of abduction torque generated by tetanic stimulation of the peronei. During SNR, pressures were higher in regions of the calcaneal tendon originating from MG than regions originating from LG. Similarly, pressures within the MG portion of the calcaneal tendon were higher during SNR than during XER, although these two reflexes produced matched ankle plantarflexion forces. Selective tenotomies and electromyographic recordings further demonstrated that MG generated most of the torque in response to SNR, while soleus, LG, and MG all generated torques in response to XER.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. A high-damping magnetorheological elastomer with bi-directional magnetic-control modulus for potential application in seismology

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Miao, E-mail: yumiao@cqu.edu.cn; Qi, Song; Fu, Jie; Zhu, Mi [Key Lab for Optoelectronic Technology and Systems, Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2015-09-14

    A high-damping magnetorheological elastomer (MRE) with bi-directional magnetic-control modulus is developed. This MRE was synthesized by filling NdFeB particles into polyurethane (PU)/ epoxy (EP) interpenetrating network (IPN) structure. The anisotropic samples were prepared in a permanent magnetic field and magnetized in an electromagnetic field of 1 T. Dynamic mechanical responses of the MRE to applied magnetic fields are investigated through magneto-rheometer, and morphology of MREs is observed via scanning electron microscope (SEM). Test result indicates that when the test field orientation is parallel to that of the sample's magnetization, the shear modulus of sample increases. On the other hand, when the orientation is opposite to that of the sample's magnetization, shear modulus decreases. In addition, this PU/EP IPN matrix based MRE has a high-damping property, with high loss factor and can be controlled by applying magnetic field. It is expected that the high damping property and the ability of bi-directional magnetic-control modulus of this MRE offer promising advantages in seismologic application.

  7. Direct-Write, Self-Aligned Electrospinning on Paper for Controllable Fabrication of Three-Dimensional Structures.

    Science.gov (United States)

    Luo, Guoxi; Teh, Kwok Siong; Liu, Yumeng; Zang, Xining; Wen, Zhiyu; Lin, Liwei

    2015-12-23

    Electrospinning, a process that converts a solution or melt droplet into an ejected jet under a high electric field, is a well-established technique to produce one-dimensional (1D) fibers or two-dimensional (2D) randomly arranged fibrous meshes. Nevertheless, the direct electrospinning of fibers into controllable three-dimensional (3D) architectures is still a nascent technology. Here, we apply near-field electrospinning (NFES) to directly write arbitrarily shaped 3D structures through consistent and spatially controlled fiber-by-fiber stacking of polyvinylidene fluoride (PVDF) fibers. An element central to the success of this 3D electrospinning is the use of a printing paper placed on the grounded conductive plate and acting as a fiber collector. Once deposited on the paper, residual solvents from near-field electrospun fibers can infiltrate the paper substrate, enhancing the charge transfer between the deposited fibers and the ground plate via the fibrous network within the paper. Such charge transfer grounds the deposited fibers and turns them into locally fabricated electrical poles, which attract subsequent in-flight fibers to deposit in a self-aligned manner on top of each other. This process enables the design and controlled fabrication of electrospun 3D structures such as grids, walls, hollow cylinders, and other 3D logos. As such, this technique has the potential to advance the existing electrospinning technologies in constructing 3D structures for biomedical, microelectronics, and MEMS/NMES applications.

  8. 直接脑控机器人接口技术%Direct Brain-controlled Robot Interface Technology

    Institute of Scientific and Technical Information of China (English)

    伏云发; 王越超; 李洪谊; 徐保磊; 李永程

    2012-01-01

    直接脑控机器人接口(Brain-controlled robot interface,BCRI)是一种新型的人-机器人接口技术,是脑-机器接口/脑-计算机接口 (Brain-machine interface,BMI/Brain-computer interface,BCI)在机器人控制领域的重要应用和研究方向.研究者相继在Nature、Science和其他重要国际期刊上报道了相关的实验研究和开发,目前已成为国际前沿研究热点.本文主要围绕BCRI中的控制策略、BMI/BCI模块与机器人多层控制模块的适应和融合、BCRI中的脑信号自适应分类算法以及人、BMI/BCI模块和机器人控制系统的三边自适应展开论述,分析了目前的研究情况、存在的局限和面临的若干重要问题,指出进一步的研究思路和方向.%Direct brain-controlled robot interface (BCRI) is a new type human-robot interface which is an important research and development direction for brain-machine interface (BMI) / brain-computer interface (BCI) in the robot control field. Many experimental researches and developments for BCRI were reported by Nature, Science and other important international journals and it has become an international frontier research hotspot. The paper mainly discussed the control strategies for BCRI, the adaptation and fusion between BMI/BCI module and robot multilayer control architecture module, the adaptive classification algorithms for brain signal used in BCRI and the trilateral adaptation among human, BMI/BCI module and robot control system. The current situation and limitation for BCRI and some important problems faced by BCRI were analyzed and the further research ideas and directions were also pointed out.

  9. Application of direct torque control to electric screw presses for speeding up torque response and reducing starting current

    Institute of Scientific and Technical Information of China (English)

    FENG Yi; HUANG Shu-huai; LI Jun-chao; XIONG Xiao-hong

    2009-01-01

    Fast response and stable torque output are crucial to the performance of electric screw presses. This paper describes the design of a direct torque control (DTC) system for speeding up torque response and reducing the starting current of electric screw presses and its application to the J58K series of numerical control electric screw presses with a dual-motor drive. The DTC drive system encompasses speed control, torque reference control, and switching frequency control. Comparison of the DTC duaI-AC induction motor drive with corresponding AC servo motor drive showed that for the J58K-315 electric screw press, the DTC drive system attains a higher maximum speed (786 r/min) within a shorter time (1.13 s) during a 250 mm stroke and undergoes smaller rise in temperature (42.0 ℃) in the motor after running for 2 h at a 12 min strike fi'equency than the AC servo motor drive does (751 r/min within 1.19 s, and 50.6 ℃ rise). Moreover, the DTC AC induction motor drive, with no need for a tachometer or position encoder to feed back the speed or position of the motor shaft, enjoys increased reliability in a strong-shock work environment.

  10. Stability of formation control using a consensus protocol under directed communications with two time delays and delay scheduling

    Science.gov (United States)

    Cepeda-Gomez, Rudy; Olgac, Nejat

    2016-01-01

    We consider a linear algorithm to achieve formation control in a group of agents which are driven by second-order dynamics and affected by two rationally independent delays. One of the delays is in the position and the other in the velocity information channels. These delays are taken as constant and uniform throughout the system. The communication topology is assumed to be directed and fixed. The formation is attained by adding a supplementary control term to the stabilising consensus protocol. In preparation for the formation control logic, we first study the stability of the consensus, using the recent cluster treatment of characteristic roots (CTCR) paradigm. This effort results in a unique depiction of the non-conservative stability boundaries in the domain of the delays. However, CTCR requires the knowledge of the potential stability switching loci exhaustively within this domain. The creation of these loci is done in a new surrogate coordinate system, called the 'spectral delay space (SDS)'. The relative stability is also investigated, which has to do with the speed of reaching consensus. This step leads to a paradoxical control design concept, called the 'delay scheduling', which highlights the fact that the group behaviour may be enhanced by increasing the delays. These steps lead to a control strategy to establish a desired group formation that guarantees spacing among the agents. Example case studies are presented to validate the underlying analytical derivations.

  11. Model reduction for the dynamics and control of large structural systems via neutral network processing direct numerical optimization

    Science.gov (United States)

    Becus, Georges A.; Chan, Alistair K.

    1993-01-01

    Three neural network processing approaches in a direct numerical optimization model reduction scheme are proposed and investigated. Large structural systems, such as large space structures, offer new challenges to both structural dynamicists and control engineers. One such challenge is that of dimensionality. Indeed these distributed parameter systems can be modeled either by infinite dimensional mathematical models (typically partial differential equations) or by high dimensional discrete models (typically finite element models) often exhibiting thousands of vibrational modes usually closely spaced and with little, if any, damping. Clearly, some form of model reduction is in order, especially for the control engineer who can actively control but a few of the modes using system identification based on a limited number of sensors. Inasmuch as the amount of 'control spillover' (in which the control inputs excite the neglected dynamics) and/or 'observation spillover' (where neglected dynamics affect system identification) is to a large extent determined by the choice of particular reduced model (RM), the way in which this model reduction is carried out is often critical.

  12. Optimum air conditioning by h,x-directed controller; Optimales Klima durch h,x-gefuehrte Regelung

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, G.; Schumacher, B. [Landis und Staefa AG, Staefa (Switzerland)

    1997-11-01

    The new `Economiser tx2` h,x-directed controller optimises control of air conditioning systems by including all process variables (heating, cooling, humidification, dehumidification) in the control strategy. Adjustments to the energy recovery and humidification system, and to the energy cost situation - e.g. cooling with a chiller or with sea water - can be implemented. At the same time, particular customer wishes can be fulfilled, for example, the size of the size of the comfort field can be increased or reduced. Cost savings of 10 to 60%, with improved comfort, are possible in comparison with conventional air conditioning control systems. The closed control strategy guarantees good dynamic behaviour and thus less wear and tear on the system. (orig.) [Deutsch] Die Strategie zur Regelung von Klimaanlagen hat sich in den letzten 20 Jahren wenig geaendert. Typisch ist zum Beispiel die Steuerung der Energierueckgewinnung nach der Enthalpie oder die Aufteilung in einen Temperatur- und Feuchteregelkreis mit jeweils energieneutralen Zonen ohne gegenseitige Abstimmung. Hier liegt zweifellos ein Optimierungspotential brach. Mit einem neuen Regelungskonzept, das sich auf das Behaglichkeitsfeld stuetzt und die spezifischen Kosten fuer die Funktionen Heizen, Kuehlen, Befeuchten und Entfeuchten in die Regelstrategie einbezieht, lassen sich ohne Komfortverzicht Energieeinsparungen von bis zu 60 Prozent erzielen. (orig.)

  13. Efficient endoderm induction from human pluripotent stem cells by logically directing signals controlling lineage bifurcations.

    Science.gov (United States)

    Loh, Kyle M; Ang, Lay Teng; Zhang, Jingyao; Kumar, Vibhor; Ang, Jasmin; Auyeong, Jun Qiang; Lee, Kian Leong; Choo, Siew Hua; Lim, Christina Y Y; Nichane, Massimo; Tan, Junru; Noghabi, Monireh Soroush; Azzola, Lisa; Ng, Elizabeth S; Durruthy-Durruthy, Jens; Sebastiano, Vittorio; Poellinger, Lorenz; Elefanty, Andrew G; Stanley, Edouard G; Chen, Qingfeng; Prabhakar, Shyam; Weissman, Irving L; Lim, Bing

    2014-02-01

    Human pluripotent stem cell (hPSC) differentiation typically yields heterogeneous populations. Knowledge of signals controlling embryonic lineage bifurcations could efficiently yield desired cell types through exclusion of alternate fates. Therefore, we revisited signals driving induction and anterior-posterior patterning of definitive endoderm to generate a coherent roadmap for endoderm differentiation. With striking temporal dynamics, BMP and Wnt initially specified anterior primitive streak (progenitor to endoderm), yet, 24 hr later, suppressed endoderm and induced mesoderm. At lineage bifurcations, cross-repressive signals separated mutually exclusive fates; TGF-β and BMP/MAPK respectively induced pancreas versus liver from endoderm by suppressing the alternate lineage. We systematically blockaded alternate fates throughout multiple consecutive bifurcations, thereby efficiently differentiating multiple hPSC lines exclusively into endoderm and its derivatives. Comprehensive transcriptional and chromatin mapping of highly pure endodermal populations revealed that endodermal enhancers existed in a surprising diversity of "pre-enhancer" states before activation, reflecting the establishment of a permissive chromatin landscape as a prelude to differentiation.

  14. Direct electrical control of IgG conformation and functional activity at surfaces

    Science.gov (United States)

    Ghisellini, Paola; Caiazzo, Marialuisa; Alessandrini, Andrea; Eggenhöffner, Roberto; Vassalli, Massimo; Facci, Paolo

    2016-11-01

    We have devised a supramolecular edifice involving His-tagged protein A and antibodies to yield surface immobilized, uniformly oriented, IgG-type, antibody layers with Fab fragments exposed off an electrode surface. We demonstrate here that we can affect the conformation of IgGs, likely pushing/pulling electrostatically Fab fragments towards/from the electrode surface. A potential difference between electrode and solution acts on IgGs’ charged aminoacids modulating the accessibility of the specific recognition regions of Fab fragments by antigens in solution. Consequently, antibody-antigen affinity is affected by the sign of the applied potential: a positive potential enables an effective capture of antigens; a negative one pulls the fragments towards the electrode, where steric hindrance caused by neighboring molecules largely hampers the capture of antigens. Different experimental techniques (electrochemical quartz crystal microbalance, electrochemical impedance spectroscopy, fluorescence confocal microscopy and electrochemical atomic force spectroscopy) were used to evaluate binding kinetics, surface coverage, effect of the applied electric field on IgGs, and role of charged residues on the phenomenon described. These findings expand the concept of electrical control of biological reactions and can be used to gate electrically specific recognition reactions with impact in biosensors, bioactuators, smart biodevices, nanomedicine, and fundamental studies related to chemical reaction kinetics.

  15. Direct control of Na(+)-K(+)-2Cl(-)-cotransport protein (NKCC1) expression with aldosterone.

    Science.gov (United States)

    Ding, Bo; Frisina, Robert D; Zhu, Xiaoxia; Sakai, Yoshihisa; Sokolowski, Bernd; Walton, Joseph P

    2014-01-01

    Sodium/potassium/chloride cotransporter (NKCC1) proteins play important roles in Na(+) and K(+) concentrations in key physiological systems, including cardiac, vascular, renal, nervous, and sensory systems. NKCC1 levels and functionality are altered in certain disease states, and tend to decline with age. A sensitive, effective way of regulating NKCC1 protein expression has significant biotherapeutic possibilities. The purpose of the present investigation was to determine if the naturally occurring hormone aldosterone (ALD) could regulate NKCC1 protein expression. Application of ALD to a human cell line (HT-29) revealed that ALD can regulate NKCC1 protein expression, quite sensitively and rapidly, independent of mRNA expression changes. Utilization of a specific inhibitor of mineralocorticoid receptors, eplerenone, implicated these receptors as part of the ALD mechanism of action. Further experiments with cycloheximide (protein synthesis inhibitor) and MG132 (proteasome inhibitor) revealed that ALD can upregulate NKCC1 by increasing protein stability, i.e., reducing ubiquitination of NKCC1. Having a procedure for controlling NKCC1 protein expression opens the doors for therapeutic interventions for diseases involving the mis-regulation or depletion of NKCC1 proteins, for example during aging.

  16. Type-2 fuzzy logic control based MRAS speed estimator for speed sensorless direct torque and flux control of an induction motor drive.

    Science.gov (United States)

    Ramesh, Tejavathu; Kumar Panda, Anup; Shiva Kumar, S

    2015-07-01

    In this research study, a model reference adaptive system (MRAS) speed estimator for speed sensorless direct torque and flux control (DTFC) of an induction motor drive (IMD) using two adaptation mechanism schemes are proposed to replace the conventional proportional integral controller (PIC). The first adaptation mechanism scheme is based on Type-1 fuzzy logic controller (T1FLC), which is used to achieve high performance sensorless drive in both transient as well as steady state conditions. However, the Type-1 fuzzy sets are certain and unable to work effectively when higher degree of uncertainties presents in the system which can be caused by sudden change in speed or different load disturbances, process noise etc. Therefore, a new Type-2 fuzzy logic controller (T2FLC) based adaptation mechanism scheme is proposed to better handle the higher degree of uncertainties and improves the performance and also robust to various load torque and sudden change in speed conditions, respectively. The detailed performances of various adaptation mechanism schemes are carried out in a MATLAB/Simulink environment with a speed sensor and speed sensorless modes of operation when an IMD is operating under different operating conditions, such as, no-load, load and sudden change in speed, respectively. To validate the different control approaches, the system also implemented on real-time system and adequate results are reported for its validation.

  17. Bubble Induced Disruption of a Planar Solid-Liquid Interface During Controlled Directional Solidification in a Microgravity Environment

    Science.gov (United States)

    Grugel, Richard N.; Brush, Lucien N.; Anilkumar, Amrutur V.

    2013-01-01

    Pore Formation and Mobility Investigation (PFMI) experiments were conducted in the microgravity environment aboard the International Space Station with the intent of better understanding the role entrained porosity/bubbles play during controlled directional solidification. The planar interface in a slowing growing succinonitrile - 0.24 wt% water alloy was being observed when a nitrogen bubble traversed the mushy zone and remained at the solid-liquid interface. Breakdown of the interface to shallow cells subsequently occurred, and was later evaluated using down-linked data from a nearby thermocouple. These results and other detrimental effects due to the presence of bubbles during solidification processing in a microgravity environment are presented and discussed.

  18. A Novel Modulation Function-Based Control of Modular Multilevel Converters for High Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Majid Mehrasa

    2016-10-01

    Full Text Available In this paper, a novel modulation function-based method including analyses of the modulation index and phase is proposed for operation of modular multilevel converters (MMCs in high voltage direct current (HVDC transmission systems. The proposed modulation function-based control technique is developed based on thorough and precise analyses of all MMC voltages and currents in the a-b-c reference frame in which the alternating current (AC-side voltage is the first target to be obtained. Using the AC-side voltage, the combination of the MMC upper and lower arm voltages is achieved as the main structure of the proposed modulation function. The main contribution of this paper is to obtain two very simple new modulation functions to control MMC performance in different operating conditions. The features of the modulation function-based control technique are as follows: (1 this control technique is very simple and can be easily achieved in a-b-c reference frame without the need of using Park transformation; and (2 in addition, the inherent properties of the MMC model are considered in the proposed control technique. Considering these properties leads to constructing a control technique that is robust against MMC parameters changes and also is a very good tracking method for the components of MMC input currents. These features lead to improving the operation of MMC significantly, which can act as a rectifier in the HVDC structure. The simulation studies are conducted through MATLAB/SIMULINK software, and the results obtained verify the effectiveness of the proposed modulation function-based control technique.

  19. Direct-trauma model of posttraumatic syringomyelia with a computer-controlled motorized spinal cord impactor.

    Science.gov (United States)

    Wong, Johnny H Y; Song, Xin; Hemley, Sarah J; Bilston, Lynne E; Cheng, Shaokoon; Stoodley, Marcus A

    2016-05-01

    OBJECTIVE The pathogenesis of posttraumatic syringomyelia remains enigmatic and is not adequately explained by current theories. Experimental investigations require a reproducible animal model that replicates the human condition. Current animal models are imperfect because of their low reliability, severe neurological deficits, or dissimilar mechanism of injury. The objective of this study was to develop a reproducible rodent model of posttraumatic syringomyelia using a spinal cord impactor that produces an injury that more closely mimics the human condition and does not produce severe neurological deficits. METHODS The study consisted of 2 parts. Seventy animals were studied overall: 20 in Experiment 1 and 48 in Experiment 2 after two rats with severe deficits were killed early. Experiment 1 aimed to determine the optimal force setting for inducing a cystic cavity without neurological deficits using a computer-controlled motorized spinal cord impactor. Twenty animals received an impact that ranged from 50 to 150 kDyn. Using the optimal force for producing an initial cyst determined from Experiment 1, Experiment 2 aimed to compare the progression of cavities in animals with and those without arachnoiditis induced by kaolin. Forty-eight animals were killed at 1, 3, 6, or 12 weeks after syrinx induction. Measurements of cavity size and maximum anteroposterior and lateral diameters were evaluated using light microscopy. RESULTS In Experiment 1, cavities were present in 95% of the animals. The duration of limb weakness and spinal cord cavity size correlated with the delivered force. The optimal force chosen for Experiment 2 was 75 kDyn. In Experiment 2, cavities occurred in 92% of the animals. Animals in the kaolin groups developed larger cavities and more vacuolations and enlarged perivascular spaces than those in the nonkaolin groups. CONCLUSIONS This impact model reliably produces cavities that resemble human posttraumatic syringomyelia and is suitable for further

  20. Airborne Contamination Control through Directed Airflow in the Exam Room: A Pilot Study Using a Membrane Diffuser

    Directory of Open Access Journals (Sweden)

    Debajyoti Pati

    2010-01-01

    Full Text Available Airborne infections have been documented as a major source of hospital acquired infection - one of the major concerns in healthcare delivery. An important factor contributing to airborne infection is cross contamination through air particulate dispersion as affected by the ventilation system design. Clean room technology (with membrane ceiling has been successfully used in technology and pharmaceutical industries to control airborne contamination. This study examined the performance of membrane ceiling technology in controlling air particulate dispersion in a mock-up exam room. It included both performance tests in a mock-up room and a simulation study of six different ventilation system designs using Computational Fluid Dynamics (CFD analysis. Findings suggest that a membrane diffuser directed airflow ventilation strategy occupying approximately 20% to 30% of the ceiling surface and placed over the patient in a contemporary sized exam room provides a less turbulent airflow pattern and less mixing of the air between the patient and others in the room.

  1. Robust design of a 2-DOF GMV controller: a direct self-tuning and fuzzy scheduling approach.

    Science.gov (United States)

    Silveira, Antonio S; Rodríguez, Jaime E N; Coelho, Antonio A R

    2012-01-01

    This paper presents a study on self-tuning control strategies with generalized minimum variance control in a fixed two degree of freedom structure-or simply GMV2DOF-within two adaptive perspectives. One, from the process model point of view, using a recursive least squares estimator algorithm for direct self-tuning design, and another, using a Mamdani fuzzy GMV2DOF parameters scheduling technique based on analytical and physical interpretations from robustness analysis of the system. Both strategies are assessed by simulation and real plants experimentation environments composed of a damped pendulum and an under development wind tunnel from the Department of Automation and Systems of the Federal University of Santa Catarina.

  2. An Experimental Study on Direct Load Control of Residential Air-conditioning Units from a Viewpoint of Short-period Controllability in Artificial Climate Chamber

    Science.gov (United States)

    Sugihara, Hideharu; Funaki, Tsuyoshi; Ueno, Kiyotaka

    Recently, much attention in Japan has been given to photovoltaic (PV) systems, which are being rapidly installed in ever greater numbers on homes. However, various concerns over potential adverse implications on the secure operation of the power systems that could result from large-scale installation of PV systems have been identified, such as large-scale PV causing frequency variations or causing voltage variations in distribution networks. This study presents findings on performing direct load control in an artificial climate chamber capable of constant outside air temperature control, and focuses on the potential for using load-variable residential Air-Conditioning (AC) units in order to promote the large-scale introduction of PV. Specifically, measurements were taken of power consumption, room temperature, suction air temperature, and blow air temperature while altering inside air temperature over several minute intervals, and the power consumption variability of AC unit was assessed, while also evaluating the effects on thermal comfort index inside the room.

  3. Controlled loading of building blocks into temporary self-assembled scaffolds for directed assembly of organic nanostructures.

    Science.gov (United States)

    Banner, L Todd; Danila, Delia C; Sharpe, Katie; Durkin, Melissa; Clayton, Benjamin; Anderson, Ben; Richter, Andrew; Pinkhassik, Eugene

    2008-10-21

    Using temporary self-assembled scaffolds to preorganize building blocks is a potentially powerful method for the synthesis of organic nanostructures with programmed shapes. We examined the underlying phenomena governing the loading of hydrophobic monomers into lipid bilayer interior and demonstrated successful control of the amount and ratio of loaded monomers. When excess styrene derivatives or acrylates were added to the aqueous solution of unilamellar liposomes made from saturated phospholipids, most loading occurs within the first few hours. Dynamic light scattering and transmission electron microscopy revealed no evidence of aggregation caused by monomers. Bilayers appeared to have a certain capacity for accommodating monomers. The total volume of loaded monomers is independent of monomer structure. X-ray scattering showed the increase in bilayer thickness consistent with loading monomers into bilayer interior. Loading kinetics is inversely proportional to the hydrophobicity and size of monomers. Loading and extraction kinetic data suggest that crossing the polar heads region is the rate limiting step. Consideration of loading kinetics and multiple equilibria are important for achieving reproducible monomer loading. The total amount of monomers loaded into the bilayer can be controlled by the loading time or length of hydrophobic lipid tails. The ratio of loaded monomers can be varied by changing the ratio of monomers used for loading or by the time-controlled replacement of a preloaded monomer. Understanding and controlling the loading of monomers into bilayers contributes to the directed assembly of organic nanostructures.

  4. Research on a direct torque control for an electrically excited synchronous motor drive with low ripple in flux and torque

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yangzhong; HU Yuwen; HUANG Wenxin; ZHONG Tianyun

    2007-01-01

    The electrically excited synchronous motor (ESM)has typically small synchronous inductance values and quite low transient values because of the damper windings mounted on the rotor.Therefore,the torque and stator flux linkage ripples are high in the direct torque control(DTC)drive of the ESM with a torque and flux linkage hysteresis controller (basic DTC).A DTC scheme with space vector modulation(SVM)for the ESM was investigated in this paper.It is based on the compensation of the stator flux linkage vector error using the space vector modulation in order to decrease the torque and flux linkage ripples and produce fixed switching frequency under the principle that the torque is controlled by the torque angle in the ESM.Compared with the basic DTC,the results of the simulation and experiment show that the torque and flux linkage rippies are reduced,the maximum current value is decreased during the startup,and the current distortion is much smaller in the steady-state under the SVM-DTC.The field-weakening control is incorporated with the SVM-DTC successfully.

  5. A New Approach to Dynamic Control of Synchronous Generator in a Bulk Electric Power System by Direct Feedback Linearization

    Directory of Open Access Journals (Sweden)

    S. Sajedi

    2011-11-01

    Full Text Available Feedback linearization is a common approach used in controlling nonlinear systems. The approach involves coming up with a transformation of the nonlinear system into an equivalent linear system through a change of variables and a suitable control input. In this paper a new control structure based on the application of the method of exact linearization by Direct Feedback Linearization for a synchronous generator is presented. The power system model consists of a single axis flat rotor machine, connected to an infinite power bus. This way the sub-transient phenomena are ignored. The global system consisting of a turbine and a generator that produces the electrical output power is coupled and it presents multiplicative and harmonic non-linearities. The application of a DFL on the output voltage equation expressed as a function of the electrical system parameters referred to the generator practically turns the non linear system into two uncoupled subsystems with the possibility of independently controlling the output voltage and the frequency.

  6. No direct association among respiratory function, disease control and family functioning in a sample of Mexican children with intermittent asthma.

    Science.gov (United States)

    Rodriguez-Orozco, Alain Raimundo; Núñez-Tapia, Rosa María; Ramírez-Silva, Armando; Gómez-Alonso, Carlos

    2013-05-15

    Asthma has been linked to family disfunctioning and poor control of the disease.This study was conducted to analyze the interactions between the level of intermittent asthma control, family functioning and respiratory function and between quality of life of asthmatic patients and their caregivers.7 to 15 years old children with intermittent asthma were included. Asthma Control Test Questionnaire, Pediatric Asthma Quality of Life Questionnaire (PAQLQ) test, and flowmetry were applied to children and Pediatric Asthma Caregiver´s Quatily of Life Questionnaire (PAQCLQ) and the Family Functioning Perception Test (FF-SIL) were applied to their parents.The most affected areas of family functioning in dysfunctional families were adaptability and permeability. A medium to high strength of association was founded between the emotional function of parents and the emotional function of children, R2=0.552. The most remarkable associations were among parents' limitation of activities and parents' emotional function (r=0.837), parents' limitation of activities and child's emotional function (r=0.722), parents' emotional role and limitation of activities (r=0.837), parents' emotional role and emotional functioning of children with asthma (r=0.743) and the limitation of activities of children with asthma and the emotional function of children with asthma (r=0.870).No direct associations were founded among respiratory function, disease control and family functioning in Mexican children with intermittent asthma and emotional function of parents and children were associated in both groups.

  7. Effects of transcranial direct current stimulation on the control of finger force during dexterous manipulation in healthy older adults.

    Directory of Open Access Journals (Sweden)

    Pranav J Parikh

    Full Text Available The contribution of poor finger force control to age-related decline in manual dexterity is above and beyond ubiquitous behavioral slowing. Altered control of the finger forces can impart unwanted torque on the object affecting its orientation, thus impairing manual performance. Anodal transcranial direct current stimulation (tDCS over primary motor cortex (M1 has been shown to improve the performance speed on manual tasks in older adults. However, the effects of anodal tDCS over M1 on the finger force control during object manipulation in older adults remain to be fully explored. Here we determined the effects of anodal tDCS over M1 on the control of grip force in older adults while they manipulated an object with an uncertain mechanical property. Eight healthy older adults were instructed to grip and lift an object whose contact surfaces were unexpectedly made more or less slippery across trials using acetate and sandpaper surfaces, respectively. Subjects performed this task before and after receiving anodal or sham tDCS over M1 on two separate sessions using a cross-over design. We found that older adults used significantly lower grip force following anodal tDCS compared to sham tDCS. Friction measured at the finger-object interface remained invariant after anodal and sham tDCS. These findings suggest that anodal tDCS over M1 improved the control of grip force during object manipulation in healthy older adults. Although the cortical networks for representing objects and manipulative actions are complex, the reduction in grip force following anodal tDCS over M1 might be due to a cortical excitation yielding improved processing of object-specific sensory information and its integration with the motor commands for production of manipulative forces. Our findings indicate that tDCS has a potential to improve the control of finger force during dexterous manipulation in older adults.

  8. Control of the Gas Flow in an Industrial Directional Solidification Furnace for Production of High Purity Multicrystalline Silicon Ingots

    Directory of Open Access Journals (Sweden)

    Lijun Liu

    2015-01-01

    Full Text Available A crucible cover was designed as gas guidance to control the gas flow in an industrial directional solidification furnace for producing high purity multicrystalline silicon. Three cover designs were compared to investigate their effect on impurity transport in the furnace and contamination of the silicon melt. Global simulations of coupled oxygen (O and carbon (C transport were carried out to predict the SiO and CO gases in the furnace as well as the O and C distributions in the silicon melt. Cases with and without chemical reaction on the cover surfaces were investigated. It was found that the cover design has little effect on the O concentration in the silicon melt; however, it significantly influences CO gas transport in the furnace chamber and C contamination in the melt. For covers made of metal or with a coating on their surfaces, an optimal cover design can produce a silicon melt free of C contamination. Even for a graphite cover without a coating, the carbon concentration in the silicon melt can be reduced by one order of magnitude. The simulation results demonstrate a method to control the contamination of C impurities in an industrial directional solidification furnace by crucible cover design.

  9. The Wnt/Planar Cell Polarity Pathway Component Vangl2 Induces Synapse Formation through Direct Control of N-Cadherin

    Directory of Open Access Journals (Sweden)

    Tadahiro Nagaoka

    2014-03-01

    Full Text Available Although regulators of the Wnt/planar cell polarity (PCP pathway are widely expressed in vertebrate nervous systems, their roles at synapses are unknown. Here, we show that Vangl2 is a postsynaptic factor crucial for synaptogenesis and that it coprecipitates with N-cadherin and PSD-95 from synapse-rich brain extracts. Vangl2 directly binds N-cadherin and enhances its internalization in a Rab5-dependent manner. This physical and functional interaction is suppressed by β-catenin, which binds the same intracellular region of N-cadherin as Vangl2. In hippocampal neurons expressing reduced Vangl2 levels, dendritic spine formation as well as synaptic marker clustering is significantly impaired. Furthermore, Prickle2, another postsynaptic PCP component, inhibits the N-cadherin-Vangl2 interaction and is required for normal spine formation. These results demonstrate direct control of classic cadherin by PCP factors; this control may play a central role in the precise formation and maturation of cell-cell adhesions at the synapse.

  10. Anodal Transcranial Direct Current Stimulation Shows Minimal, Measure-Specific Effects on Dynamic Postural Control in Young and Older Adults: A Double Blind, Sham-Controlled Study.

    Science.gov (United States)

    Craig, Chesney E; Doumas, Michail

    2017-01-01

    We investigated whether stimulating the cerebellum and primary motor cortex (M1) using transcranial direct current stimulation (tDCS) could affect postural control in young and older adults. tDCS was employed using a double-blind, sham-controlled design, in which young (aged 18-35) and older adults (aged 65+) were assessed over three sessions, one for each stimulatory condition-M1, cerebellar and sham. The effect of tDCS on postural control was assessed using a sway-referencing paradigm, which induced platform rotations in proportion to the participant's body sway, thus assessing sensory reweighting processes. Task difficulty was manipulated so that young adults experienced a support surface that was twice as compliant as that of older adults, in order to minimise baseline age differences in postural sway. Effects of tDCS on postural control were assessed during, immediately after and 30 minutes after tDCS. Additionally, the effect of tDCS on corticospinal excitability was measured by evaluating motor evoked potentials using transcranial magnetic stimulation immediately after and 30 minutes after tDCS. Minimal effects of tDCS on postural control were found in the eyes open condition only, and this was dependent on the measure assessed and age group. For young adults, stimulation had only offline effects, as cerebellar stimulation showed higher mean power frequency (MPF) of sway 30 minutes after stimulation. For older adults, both stimulation conditions delayed the increase in sway amplitude witnessed between blocks one and two until stimulation was no longer active. In conclusion, despite tDCS' growing popularity, we would caution researchers to consider carefully the type of measures assessed and the groups targeted in tDCS studies of postural control.

  11. 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.;

    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 ...

  12. A nudge in a healthier direction: How environmental cues help restrained eaters pursue their weight-control goal.

    Science.gov (United States)

    Stämpfli, Aline E; Stöckli, Sabrina; Brunner, Thomas A

    2017-03-01

    Losing weight is a goal for many people, but it is hard to pursue. However, dieting cues in the environment hold promise for improving individuals' eating behavior. For example, exposure to thin, human-like sculptures by the artist Alberto Giacometti has been found to promote healthy snack choices at a vending machine. Whether health- or weight-related processes drive such effects has not yet been determined. However, a detailed understanding of the content-related drivers of environmental cues' effects provides the first indications regarding a cue's possible use. Therefore, two laboratory studies were conducted. They examined the Giacometti sculptures' effects on unhealthy and healthy food intake (Study 1) and on the completion of weight- and health-related fragmented words (Study 2). Study 1 indicated that the sculptures are weight-related by showing that they reduced food intake independent of food healthiness. Furthermore, the "Giacometti effect" was moderated by restrained eating. Restrained eaters, who are known for their weight-control goal, ate less after having been exposed to the thin sculptures. The results of Study 2 pointed in the same direction. Restrained eaters completed more weight-related words after being exposed to the sculptures. Overall, these studies suggest that the thin sculptures are primarily weight-related cues and particularly helpful for restrained eaters. Environmental weight-control cues such as the Giacometti sculptures could act as a counterforce to our obesogenic environment and help restrained eaters pursue their weight-control goal. In this way, they could nudge food decisions in a healthier direction.

  13. Stimulation of Dorsolateral Prefrontal Cortex Enhances Adaptive Cognitive Control: A High-Definition Transcranial Direct Current Stimulation Study.

    Science.gov (United States)

    Gbadeyan, Oyetunde; McMahon, Katie; Steinhauser, Marco; Meinzer, Marcus

    2016-12-14

    Conflict adaptation is a hallmark effect of adaptive cognitive control and refers to the adjustment of control to the level of previously experienced conflict. Conflict monitoring theory assumes that the dorsolateral prefrontal cortex (DLPFC) is causally involved in this adjustment. However, to date, evidence in humans is predominantly correlational, and heterogeneous with respect to the lateralization of control in the DLPFC. We used high-definition transcranial direct current stimulation (HD-tDCS), which allows for more focal current delivery than conventional tDCS, to clarify the causal involvement of the DLPFC in conflict adaptation. Specifically, we investigated the regional specificity and lateralization of potential beneficial stimulation effects on conflict adaptation during a visual flanker task. One hundred twenty healthy participants were assigned to four HD-tDCS conditions: left or right DLPFC or left or right primary motor cortex (M1). Each group underwent both active and sham HD-tDCS in crossover, double-blind designs. We obtained a sizeable conflict adaptation effect (measured as the modulation of the flanker effect as a function of previous response conflict) in all groups and conditions. However, this effect was larger under active HD-tDCS than under sham stimulation in both DLPFC groups. In contrast, active stimulation had no effect on conflict adaptation in the M1 groups. In sum, the present results indicate that the DLPFC plays a causal role in adaptive cognitive control, but that the involvement of DLPFC in control is not restricted to the left or right hemisphere. Moreover, our study confirms the potential of HD-tDCS to modulate cognition in a regionally specific manner.

  14. Hybridization and control of a mobile direct methanol fuel cell system; Hybridisierung und Regelung eines mobilen Direktmethanol-Brennstoffzellen-Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelm, Joerg Christoph

    2010-07-01

    Direct methanol fuel cells (DMFCs) are characterized by the fact that they directly convert the chemical energy of the liquid fuel methanol into electrical energy. Methanol has a high energy density and can be stored relatively easily. Due to these advantages, direct methanol fuel cell systems are suitable, for example, as a battery replacement for light-traction applications in the kW class. Since refuelling is much faster than recharging a battery, almost interruption-free operation is possible. The aim of this thesis is therefore to develop a direct methanol fuel cell system for light-traction applications. The systems technology development and characterization of a mobile direct methanol fuel cell system is initially examined in general and then applied to the example of a horizontal order picker, a type of forklift truck. A hybridization and control concept is developed for this type of truck. The procedure is structured into the theoretical characterization of the application, the development of theoretical concepts and a concluding systems analysis using data from the test stand and simulations. The characteristic driving cycle of the application results from the characterization. The concept development is based on key data such as maximum peak power during acceleration and braking as well as average power. The two-stage theoretical development of a hybridization concept is based on a pure fuel cell vehicle. A systems analysis of all possible concepts with respect to the criteria of fuel cell power, total system efficiency and dynamic fuel cell loading eventually leads to the preferred concept of indirect coupling. A cascade controller with map control, the control concept developed for this purpose, keeps the energy storage unit at a constant state of charge and provides for the fuel cell aging protection as well as aging detection. The driving cycle, operational states of the vehicle and the efficiencies of the individual components play a decisive role

  15. A New Scheme to Direct Torque Control of Matrix Converter-Fed Five-Phase Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Sayyed Asghar Gholamian

    2013-07-01

    Full Text Available Multiphase machines have gained an increasing attention due to their more advantages in comparison with three-phase machines. In recent literatures, only voltage source inverters (VSIs have been used to supply five-phase drives. Matrix converters (MCs pose many advantages over conventional VSIs, such as lack of dc-bulk capacitors, high quality power output waveform and higher number of output voltages. Due to some special applications of multiphase machines such as ship propulsion and aerospace, the volume of these drives is an important challenging problem. As a consequence, using MCs can be a reasonable alternative. In this paper, a new direct torque control (DTC algorithm using a three-to-five phase MC is proposed for five-phase permanent magnet synchronous motors (PMSMs. All of output voltage space vectors of three-to-five phase MC are extracted and a new switching table is proposed. Because of higher number of output voltages in MCs, there is a degree of freedom to control input power factor to keep close to unit moreover the torque and flux control. In other words, this proposed method use the advantages of both DTC method and MCs. Simulation results show the effectiveness of presented method in different operation modes.

  16. Direct and contactless electrical control of temperature of paper and textile foldable substrates using electrospun metallic-web transparent electrodes.

    Science.gov (United States)

    Busuioc, Cristina; Evanghelidis, Alexandru; Galatanu, Andrei; Enculescu, Ionut

    2016-10-10

    Multiple and complex functionalities are a demand nowadays for almost all materials, including common day-to-day materials such as paper, textiles, wood, etc. In the present report, the surface temperature control of different types of materials, including paper and textiles, was demonstrated by Joule heating of metallic-web transparent electrodes both by direct current and by RF induced eddy currents. Polymeric submicronic fiber webs were prepared by electrospinning, and metal sputtering was subsequently performed to transform them into flexible transparent electrodes. These electrodes were thermally attached to different substrates, including paper, textiles and glass. Using thermochromic inks, we demonstrated a high degree of control of the substrates' surface temperature by means of the Joule effect. Metallic fiber webs appear to be excellently suited for use as transparent electrodes for controlling the surface temperature of common materials, their highly flexible nature being a major advantage when dealing with rough, bendable substrates. This kind of result could not be achieved on bendable substrates with rough surfaces such as paper or textiles while employing classical transparent electrodes i.e. metal oxides. Moreover, contactless heating with induced currents is a premiere for transparent electrodes and opens up a score of new application fields.

  17. Direct Torque Control with Full Order Stator Flux Observer for Dual-Three Phase Induction Motor Drives

    Science.gov (United States)

    Farina, Francesco; Bojoi, Radu; Tenconi, Alberto; Profumo, Francesco

    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 with isolated neutral points. The proposed control strategy is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. To improve the flux estimation, an Adaptive Stator Flux Observer (ASFO) has been used. Doing so, besides a better flux estimation in contrast to open-loop flux estimators, it is possible to use the observed currents to compensate the inverter non-linear behavior (such as dead-time effects), improving the drive performance at low speed. This is particularly important for low voltage/high current applications, as the drive considered in this paper. The advantages of the discussed control strategy are: constant inverter switching frequency, good transient and steady-state performance and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Experimental results are presented for a 10kW dual three-phase induction motor drive prototype.

  18. Direct and contactless electrical control of temperature of paper and textile foldable substrates using electrospun metallic-web transparent electrodes

    Science.gov (United States)

    Busuioc, Cristina; Evanghelidis, Alexandru; Galatanu, Andrei; Enculescu, Ionut

    2016-10-01

    Multiple and complex functionalities are a demand nowadays for almost all materials, including common day-to-day materials such as paper, textiles, wood, etc. In the present report, the surface temperature control of different types of materials, including paper and textiles, was demonstrated by Joule heating of metallic-web transparent electrodes both by direct current and by RF induced eddy currents. Polymeric submicronic fiber webs were prepared by electrospinning, and metal sputtering was subsequently performed to transform them into flexible transparent electrodes. These electrodes were thermally attached to different substrates, including paper, textiles and glass. Using thermochromic inks, we demonstrated a high degree of control of the substrates’ surface temperature by means of the Joule effect. Metallic fiber webs appear to be excellently suited for use as transparent electrodes for controlling the surface temperature of common materials, their highly flexible nature being a major advantage when dealing with rough, bendable substrates. This kind of result could not be achieved on bendable substrates with rough surfaces such as paper or textiles while employing classical transparent electrodes i.e. metal oxides. Moreover, contactless heating with induced currents is a premiere for transparent electrodes and opens up a score of new application fields.

  19. Directed self-assembly of mesoscopic electronic components into sparse arrays with controlled orientation using diamagnetic levitation

    Energy Technology Data Exchange (ETDEWEB)

    Tkachenko, Anton, E-mail: tkacha@rpi.edu; Lu, James J.-Q.

    2015-07-01

    This paper presents a directed self-assembly (DSA) approach for assembling small electronic components, such as semiconductor dies, into sparse 2D arrays using diamagnetic levitation. The dies attached to a diamagnetic layer can be levitated at a room temperature over a stage made of magnets arranged in a checkerboard pattern. By selecting a proper die design, levitation height, and vibration pattern of the magnetic stage we assemble the dies into a regular 2D array with a specific lateral and vertical orientation of the dies. The assembled dies are transferred to a receiving substrate using capillary force. - Highlights: • Self-assembly of semiconductor dies into arrays using diamagnetic levitation. • Control over the die orientation in vertical and lateral dimensions. • Simulation shows good scalability of assembly time with the number of dies. • Suitable for assembly of LED panels, displays and microcell photovoltaics.

  20. Improving the Drive System of Permanent Magnet Linear Synchronous Motor Based on Direct Thrust Force Control Applying Space Vector Modulation

    Directory of Open Access Journals (Sweden)

    Mehdi Manoochehri

    2012-07-01

    Full Text Available Applying the direct thrust force control (DFC method in permanent magnet linear synchronous motor (PMLSM leads to some important problems. The most important disadvantages of applying this method are electromagnetic force and linkage flux big ripple and variable switching frequency. In this paper space vector modulation (SVM technique is applied for removing the disadvantages of classic DFC method. SVM technique makes the switching frequency constant and provides continues Voltage space compared with discrete space in classic method. Simulation results confirmed the theory. They show that combining the DFC method with SVM technique removes lots of the disadvantages of classic DFC method like big ripples and variable switching and remains the benefits of this method.

  1. No direct association among respiratory function, disease control and family functioning in a sample of Mexican children with intermittent asthma.

    Directory of Open Access Journals (Sweden)

    Alain Raimundo Rodriguez-Orozco

    2013-06-01

    Full Text Available Asthma has been linked to family disfunctioning and poor control of the disease.This study was conducted to analyze the interactions between the level of intermittent asthma control, family functioning and respiratory function and between quality of life of asthmatic patients and their caregivers.7 to 15 years old children with intermittent asthma were included. Asthma Control Test Questionnaire,  Pediatric  Asthma  Quality  of  Life  Questionnaire   (PAQLQ   test,  and flowmetry were applied  to  children  and  Pediatric  Asthma  Caregiver´s Quatily of  Life Questionnaire  (PAQCLQ  and  the  Family Functioning  Perception  Test  (FF-SIL were applied to their parents.The most affected areas of family functioning in dysfunctional families were adaptability and permeability. A medium  to  high strength  of  association was founded  between  the emotional function of parents and the emotional function of children, R2=0.552. The most remarkable associations were among parents’ limitation of activities and parents' emotional function (r=0.837, parents’ limitation of activities and child's emotional function (r=0.722, parents' emotional role and limitation of activities (r=0.837, parents’ emotional role and emotional functioning of children with asthma (r=0.743 and the limitation of activities of children with asthma and the emotional function of children with asthma (r=0.870.No  direct associations were founded  among respiratory function, disease control  and family functioning in Mexican children with intermittent asthma and emotional function of parents and children were associated in both groups.

  2. Effect of removing direct payment for health care on utilisation and health outcomes in Ghanaian children: a randomised controlled trial.

    Directory of Open Access Journals (Sweden)

    Evelyn Korkor Ansah

    2009-01-01

    Full Text Available BACKGROUND: Delays in accessing care for malaria and other diseases can lead to disease progression, and user fees are a known barrier to accessing health care. Governments are introducing free health care to improve health outcomes. Free health care affects treatment seeking, and it is therefore assumed to lead to improved health outcomes, but there is no direct trial evidence of the impact of removing out-of-pocket payments on health outcomes in developing countries. This trial was designed to test the impact of free health care on health outcomes directly. METHODS AND FINDINGS: 2,194 households containing 2,592 Ghanaian children under 5 y old were randomised into a prepayment scheme allowing free primary care including drugs, or to a control group whose families paid user fees for health care (normal practice; 165 children whose families had previously paid to enrol in the prepayment scheme formed an observational arm. The primary outcome was moderate anaemia (haemoglobin [Hb] < 8 g/dl; major secondary outcomes were health care utilisation, severe anaemia, and mortality. At baseline the randomised groups were similar. Introducing free primary health care altered the health care seeking behaviour of households; those randomised to the intervention arm used formal health care more and nonformal care less than the control group. Introducing free primary health care did not lead to any measurable difference in any health outcome. The primary outcome of moderate anaemia was detected in 37 (3.1% children in the control and 36 children (3.2% in the intervention arm (adjusted odds ratio 1.05, 95% confidence interval 0.66-1.67. There were four deaths in the control and five in the intervention group. Mean Hb concentration, severe anaemia, parasite prevalence, and anthropometric measurements were similar in each group. Families who previously self-enrolled in the prepayment scheme were significantly less poor, had better health measures, and used

  3. Goal-directed diuresis: A case - control study of continuous furosemide infusion in critically ill trauma patients

    Directory of Open Access Journals (Sweden)

    Daniel Dante Yeh

    2015-01-01

    Full Text Available Background: Excessive crystalloid administration is common and associated with negative outcomes in critically ill trauma patients. Continuous furosemide infusion (CFI to remove excessive fluid has not been previously described in this population. We hypothesized that a goal-directed CFI is more effective for fluid removal than intermittent bolus injection (IBI diuresis without excess incidence of hypokalemia or renal failure. Materials and Methods: CFI cases were prospectively enrolled between November 2011 and August 2012, and matched to historic IBI controls by age, gender, Injury Severity Score (ISS, and net fluid balance (NFB at diuresis initiation. Paired and unpaired analyses were performed to compare groups. The primary endpoints were net fluid balance, potassium and creatinine levels. Secondary endpoints included intensive care unit (ICU and hospital length of stay (LOS, ventilator-free days (VFD, and mortality. Results: 55 patients were included, with 19 cases and 36 matched controls. Mean age was 54 years, mean ISS was 32.7, and mean initial NFB was +7.7 L. After one day of diuresis with CFI vs. IBI, net 24 h fluid balance was negative (−0.55 L vs. +0.43 L, P = 0.026 only for the CFI group, and there was no difference in potassium and creatinine levels. Cumulative furosemide dose (59.4mg vs. 25.4mg, P < 0.001 and urine output (4.2 L vs. 2.8 L, P < 0.001 were also significantly increased with CFI vs. IBI. There were no statistically significant differences in ICU LOS, hospital LOS, VFD, or mortality. Conclusions: Compared to IBI, goal-directed diuresis by CFI is more successful in achieving net negative fluid balance in patients with fluid overload with no detrimental side effects on renal function or patient outcome.

  4. A Randomized Controlled Trial Comparing the McKenzie Method to Motor Control Exercises in People With Chronic Low Back Pain and a Directional Preference.

    Science.gov (United States)

    Halliday, Mark H; Pappas, Evangelos; Hancock, Mark J; Clare, Helen A; Pinto, Rafael Z; Robertson, Gavin; Ferreira, Paulo H

    2016-07-01

    Study Design Randomized clinical trial. Background Motor control exercises are believed to improve coordination of the trunk muscles. It is unclear whether increases in trunk muscle thickness can be facilitated by approaches such as the McKenzie method. Furthermore, it is unclear which approach may have superior clinical outcomes. Objectives The primary aim was to compare the effects of the McKenzie method and motor control exercises on trunk muscle recruitment in people with chronic low back pain classified with a directional preference. The secondary aim was to conduct a between-group comparison of outcomes for pain, function, and global perceived effect. Methods Seventy people with chronic low back pain who demonstrated a directional preference using the McKenzie assessment were randomized to receive 12 treatments over 8 weeks with the McKenzie method or with motor control approaches. All outcomes were collected at baseline and at 8-week follow-up by blinded assessors. Results No significant between-group difference was found for trunk muscle thickness of the transversus abdominis (-5.8%; 95% confidence interval [CI]: -15.2%, 3.7%), obliquus internus (-0.7%; 95% CI: -6.6%, 5.2%), and obliquus externus (1.2%; 95% CI: -4.3%, 6.8%). Perceived recovery was slightly superior in the McKenzie group (-0.8; 95% CI: -1.5, -0.1) on a -5 to +5 scale. No significant between-group differences were found for pain or function (P = .99 and P = .26, respectively). Conclusion We found no significant effect of treatment group for trunk muscle thickness. Participants reported a slightly greater sense of perceived recovery with the McKenzie method than with the motor control approach. Level of Evidence Therapy, level 1b-. Registered September 7, 2011 at www.anzctr.org.au (ACTRN12611000971932). J Orthop Sports Phys Ther 2016;46(7):514-522. Epub 12 May 2016. doi:10.2519/jospt.2016.6379.

  5. Enhanced Control for a Direct-driven Permanent Synchronous Generator Wind-power Generation System with Flywheel Energy Storage Unit Under Unbalanced Grid Fault

    DEFF Research Database (Denmark)

    Yao, Jun; Zhou, Te; Hu, Weihao;

    2015-01-01

    This article presents an enhanced control strategy for a direct-driven permanent synchronous generator based wind-power generation system with a flywheel energy storage unit. The behaviors of the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit under......, the DC-link voltage oscillations can be effectively suppressed during the unbalanced grid fault by controlling the flywheel energy storage unit. Furthermore, a proportional–integral-resonant controller is designed for the flywheel motor to eliminate the oscillations in the DC-link voltage. Finally......, the proposed coordinated control strategy for the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit has been validated by the simulation results of a 1-MW direct-driven permanent magnet synchronous generator wind power generation system with a flywheel energy...

  6. A tool for stability and power sharing analysis of a generalized class of droop controllers for high-voltage direct-current transmission systems

    OpenAIRE

    2016-01-01

    The problem of primary control of high-voltage direct current transmission systems is addressed in this paper, which contains four main contributions. First, to propose a new nonlinear, more realistic, model for the system suitable for primary control design, which takes into account nonlinearities introduced by conventional inner controllers. Second, to determine necessary conditions---dependent on some free controller tuning parameters---for the existence of equilibria. Third, to formulate ...

  7. Enhancement of couples' communication and dyadic coping by a self-directed approach: a randomized controlled trial.

    Science.gov (United States)

    Bodenmann, Guy; Hilpert, Peter; Nussbeck, Fridtjof W; Bradbury, Thomas N

    2014-08-01

    Although prevention of relationship distress and dissolution has potential to strengthen the well-being of partners and any children they are raising, dissemination of prevention programs can be limited because couples face many barriers to in-person participation. An alternative strategy, providing couples with an instructional DVD, is tested in the present study, in which 330 Caucasian couples (N = 660 participants; mean age: men 41.4 years, women 40.0 years) were randomly assigned to a DVD group without any further support, a DVD group with technical telephone coaching, or a wait-list control group. Couples completed questionnaires at pretest, posttest, and 3 and 6 months after completion of the intervention. Self-report measures of dyadic coping, communication quality, ineffective arguing, and relationship satisfaction were used to test whether the intervention groups improved in comparison with the control group. Women in both intervention groups increased in dyadic coping, reduced conflict behavior, and were more satisfied with their relationship 6 months after the intervention. Effects for men were mixed. Participants with poorer skills reported stronger improvement. Intimate relationships can, within limits, be positively influenced by a self-directed approach. Effective dissemination of principles underlying successful relationships can be facilitated through the use of emerging low-cost tools and technologies.

  8. Rif1 controls DNA replication by directing Protein Phosphatase 1 to reverse Cdc7-mediated phosphorylation of the MCM complex.

    Science.gov (United States)

    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

    2014-02-15

    Initiation of eukaryotic DNA replication requires phosphorylation of the MCM complex by Dbf4-dependent kinase (DDK), composed of Cdc7 kinase and its activator, Dbf4. We report here that budding yeast Rif1 (Rap1-interacting factor 1) controls DNA replication genome-wide and describe how Rif1 opposes DDK function by directing Protein Phosphatase 1 (PP1)-mediated dephosphorylation of the MCM complex. Deleting RIF1 partially compensates for the limited DDK activity in a cdc7-1 mutant strain by allowing increased, premature phosphorylation of Mcm4. PP1 interaction motifs within the Rif1 N-terminal domain are critical for its repressive effect on replication. We confirm that Rif1 interacts with PP1 and that PP1 prevents premature Mcm4 phosphorylation. Remarkably, our results suggest that replication repression by Rif1 is itself also DDK-regulated through phosphorylation near the PP1-interacting motifs. Based on our findings, we propose that Rif1 is a novel PP1 substrate targeting subunit that counteracts DDK-mediated phosphorylation during replication. Fission yeast and mammalian Rif1 proteins have also been implicated in regulating DNA replication. Since PP1 interaction sites are evolutionarily conserved within the Rif1 sequence, it is likely that replication control by Rif1 through PP1 is a conserved mechanism.

  9. Rif1 controls DNA replication by directing Protein Phosphatase 1 to reverse Cdc7-mediated phosphorylation of the MCM complex

    Science.gov (United States)

    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

    Initiation of eukaryotic DNA replication requires phosphorylation of the MCM complex by Dbf4-dependent kinase (DDK), composed of Cdc7 kinase and its activator, Dbf4. We report here that budding yeast Rif1 (Rap1-interacting factor 1) controls DNA replication genome-wide and describe how Rif1 opposes DDK function by directing Protein Phosphatase 1 (PP1)-mediated dephosphorylation of the MCM complex. Deleting RIF1 partially compensates for the limited DDK activity in a cdc7-1 mutant strain by allowing increased, premature phosphorylation of Mcm4. PP1 interaction motifs within the Rif1 N-terminal domain are critical for its repressive effect on replication. We confirm that Rif1 interacts with PP1 and that PP1 prevents premature Mcm4 phosphorylation. Remarkably, our results suggest that replication repression by Rif1 is itself also DDK-regulated through phosphorylation near the PP1-interacting motifs. Based on our findings, we propose that Rif1 is a novel PP1 substrate targeting subunit that counteracts DDK-mediated phosphorylation during replication. Fission yeast and mammalian Rif1 proteins have also been implicated in regulating DNA replication. Since PP1 interaction sites are evolutionarily conserved within the Rif1 sequence, it is likely that replication control by Rif1 through PP1 is a conserved mechanism. PMID:24532715

  10. Theory of a Directive Optical Leaky Wave Antenna Integrated into a Resonator and Enhancement of Radiation Control

    CERN Document Server

    Guclu, Caner; Boyraz, Ozdal; Capolino, Filippo

    2013-01-01

    We provide for the first time the detailed study of the radiation performance of an optical leaky wave antenna (OLWA) integrated into a Fabry-P\\'erot resonator. We show that the radiation pattern can be expressed as the one generated by the interference of two leaky waves counter-propagating in the resonator leading to a design procedure for achieving optimized broadside radiation, i.e., normal to the waveguide axis. We thus report a realizable implementation of the OLWA made of semiconductor and dielectric regions. The theoretical modeling is supported by full-wave simulation results, which are found to be in good agreement. We aim to control the radiation intensity in the broadside direction via excess carrier generation in the semiconductor regions. We show that the presence of the resonator can provide an effective way of enhancing the radiation level modulation, which reaches values as high as 13.5 dB, paving the way for novel promising control capabilities that might allow the generation of very fast op...

  11. Effects of transcranial direct current stimulation (tDCS) on cognition, symptoms, and smoking in schizophrenia: A randomized controlled study.

    Science.gov (United States)

    Smith, Robert C; Boules, Sylvia; Mattiuz, Sanela; Youssef, Mary; Tobe, Russell H; Sershen, Henry; Lajtha, Abel; Nolan, Karen; Amiaz, Revital; Davis, John M

    2015-10-01

    Schizophrenia is characterized by cognitive deficits which persist after acute symptoms have been treated or resolved. Transcranial direct current stimulation (tDCS) has been reported to improve cognition and reduce smoking craving in healthy subjects but has not been as carefully evaluated in a randomized controlled study for these effects in schizophrenia. We conducted a randomized double-blind, sham-controlled study of the effects of 5 sessions of tDCS (2 milliamps for 20minutes) on cognition, psychiatric symptoms, and smoking and cigarette craving in 37 outpatients with schizophrenia or schizoaffective disorder who were current smokers. Thirty subjects provided evaluable data on the MATRICS Consensus Cognitive Battery (MCCB), with the primary outcome measure, the MCCB Composite score. Active compared to sham tDCS subjects showed significant improvements after the fifth tDCS session in MCCB Composite score (p=0.008) and on the MCCB Working Memory (p=0.002) and Attention-Vigilance (p=0.027) domain scores, with large effect sizes. MCCB Composite and Working Memory domain scores remained significant at Benjamini-Hochberg corrected significance levels (α=0.05). There were no statistically significant effects on secondary outcome measures of psychiatric symptoms (PANSS scores), hallucinations, cigarette craving, or cigarettes smoked. The positive effects of tDCS on cognitive performance suggest a potential efficacious treatment for cognitive deficits in partially recovered chronic schizophrenia outpatients that should be further investigated.

  12. Direct effects of locally administered lipopolysaccharide on glucose, lipid, and protein metabolism in the placebo-controlled, bilaterally infused human leg

    DEFF Research Database (Denmark)

    Buhl, Mads; Bosnjak, Ermina; Vendelbo, Mikkel H;

    2013-01-01

    discrimination between direct and indirect effects impossible. Objective: We sought to define the direct, placebo-controlled effects of LPS on insulin resistance and protein and lipid metabolism in the infused human leg without systemic interference from cytokines and stress hormones. Design...

  13. Direct digital control of furnaces irradiated in nuclear reactors; Surveillance et regulation multiplexee par calculateur numerique de fours irradies

    Energy Technology Data Exchange (ETDEWEB)

    Joumard, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    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) [French] Une installation de controle numerique direct fut realisee a titre experimental au C.E.N.G pour verifier qu'un ordinateur rendait plus aisee l'exploitation des experiences faites en pile nucleaire et pour degager les difficultes theoriques et techniques. La regulation s'applique a des processus thermiques. La theorie des systemes echantillonnes a permis de choisir un type de correcteur numerique simple et efficace et d'etablir un abaque qui donne les valeurs des parametres correcteurs minimisant les ecarts enregistres entre la reponse et la consigne en presence de perturbations. Le programme effectuait simultanement de la surveillance et de la regulation. Une restitution complexe des informations et des alarmes sur machine a ecrire etait possible. Le calculateur elaborait une correction incrementielle qui faisait tourner des moteurs pas a pas, lesquels commandaient les organes de puissance de chauffage. Les valeurs

  14. A Randomized Double-Blind Sham-Controlled Study of Transcranial Direct Current Stimulation for Treatment-Resistant Major Depression

    Directory of Open Access Journals (Sweden)

    Daniel eBlumberger

    2012-08-01

    Full Text Available Objectives: Transcranial direct current stimulation (tDCS has demonstrated some efficacy in treatment-resistant major depression (TRD. The majority of previous controlled studies have used anodal stimulation to the left dorsolateral prefrontal cortex (DLPFC and a control location such as the supraorbital region on for the cathode. Several open label studies have suggested effectiveness from anodal stimulation to the left DLPFC combined with cathodal stimulation to the right DLPFC. Thus, this study evaluated the efficacy of tDCS using anodal stimulation to the left DLPFC and cathodal stimulation to the right DLPFC compared to sham tDCS. Methods: Subjects between the ages of 18 and 65 were recruited from a tertiary care university hospital. Twenty-four subjects with TRD and a 17-item Hamilton Depression Rating Scale (HDRS greater than 21 were randomized to receive tDCS or sham tDCS. The rates of remission were compared between the two treatment groups.Results: The remission rates did not differ significantly between the two groups using an intention to treat analysis. More subjects in the active tDCS group had failed a course of electroconvulsive therapy in the current depressive episode. Side effects did not differ between the two groups and in general the treatment was very well tolerated. Conclusion: Anodal stimulation to the left DLPFC and cathodal stimulation to the right DLPFC was not efficacious in TRD. However, a number of methodological limitations warrant caution in generalizing from this study. Ongoing, controlled studies should provide further clarification on the efficacy of this stimulation configuration in TRD.

  15. A Randomized, Double-Blind, Sham-Controlled Trial of Transcranial Direct Current Stimulation in Attention-Deficit/Hyperactivity Disorder.

    Directory of Open Access Journals (Sweden)

    Camila Cosmo

    Full Text Available Current standardized treatments for cognitive impairment in attention-deficit/hyperactivity disorder remain limited and their efficacy restricted. Transcranial direct current stimulation (tDCS is a promising tool for enhancing cognitive performance in several neuropsychiatric disorders. Nevertheless, the effects of tDCS in reducing cognitive impairment in patients with attention-deficit/hyperactivity disorder (ADHD have not yet been investigated.A parallel, randomized, double-blind, sham-controlled trial was conducted to examine the efficacy of tDCS on the modulation of inhibitory control in adults with ADHD. Thirty patients were randomly allocated to each group and performed a go/no-go task before and after a single session of either anodal stimulation (1 mA over the left dorsolateral prefrontal cortex or sham stimulation.A nonparametric two-sample Wilcoxon rank-sum (Mann-Whitney test revealed no significant differences between the two groups of individuals with ADHD (tDCS vs. sham in regard to behavioral performance in the go/no go tasks. Furthermore, the effect sizes of group differences after treatment for the primary outcome measures-correct responses, impulsivity and omission errors--were small. No adverse events resulting from stimulation were reported.According to these findings, there is no evidence in support of the use of anodal stimulation over the left dorsolateral prefrontal cortex as an approach for improving inhibitory control in ADHD patients. To the best of our knowledge, this is the first clinical study to assess the cognitive effects of tDCS in individuals with ADHD. Further research is needed to assess the clinical efficacy of tDCS in this population.ClinicalTrials.gov NCT01968512.

  16. Transient analysis and control of bias magnetic state in the transformer of on-line pulse-width-modulation switching full bridge direct current-direct current converter

    Science.gov (United States)

    Chen, Jiaxin; Guo, Youguang; Zhu, Jianguo; Wei Lin, Zhi

    2012-04-01

    This paper presents a finite element analysis (FEA) based method for analyzing and controlling the bias magnetic state of the transformer of a pulse-width-modulation (PWM) switching full bridge dc-dc converter. A field-circuit indirect coupling method for predicting the transient bias magnetic state is introduced first. To increase flexibility of the proposed method, a novel transformer model which can address not only its basic input-output characteristic, but also the nonlinear magnetizing inductance, is proposed. Both the asymmetric characteristic and the variable laws of the current flowing through the two secondary windings during the period of PWM switching-off state are highlighted. Finally, the peak magnetizing current controlled method based on the on-line magnetizing current computation is introduced. Analysis results show that this method can address the magnetic saturation at winding ends, and hence many previous difficulties, such as the start-up process and asymmetry of power electronics, can be easily controlled.

  17. High speed flux feedback for tuning a universal field oriented controller capable of operating in direct and indirect field orientation modes

    Science.gov (United States)

    De Doncker, Rik W. A. A.

    1992-01-01

    The direct (d) and quadrature (q) components of flux, as sensed by flux sensors or determined from voltage and current measurements in a direct field orientation scheme, are processed rapidly and accurately to provide flux amplitude and angular position values for use by the vector rotator of a universal field-oriented (UFO) controller. Flux amplitude (linear or squared) is provided as feedback to tune the UFO controller for operation in direct and indirect field orientation modes and enables smooth transitions from one mode to the other.

  18. Directly observed treatment short course in immunocompetent patients of tuberculous cervical lymphadenopathy treated in revised national tuberculosis control programme

    Directory of Open Access Journals (Sweden)

    Venu Kandala

    2012-01-01

    Full Text Available Background: Prospective observation analysis to evaluate the cure in tuberculous cervical lymphadenopathy with directly observed treatment short course category III (DOTS CAT III treatment as per revised national tuberculosis control program (RNTCP at a tertiary care hospital in AP, India, from October 2007 to September 2009. These cases were followed up for period of 22 months. Materials and Methods: Total 1521 tuberculous cases were screened in KIMS both pulmonary and extra pulmonary cases out of which 146 cases were tuberculous lymphadenitis. Fifty cases of tuberculous cervical lymphadenopathy were included after diagnostic and treatment algorithm and fine needle biopsy or excision biopsy. Patients below 5 yrs, immunocompromised, having diabetes mellitus, pulmonary tuberculosis and with other co-morbid conditions were excluded from the study. All patients were put on DOTS CAT III as per RNTCP guidelines. Follow-up was done every 2 months till 6 months for 1 Constitution symptoms 2 Weight gain or loss 3 Appetite gain or loss 4 Regression of lymph nodes or increase 5 Compliance 6 Side effects 7 Failures by demonstration of organism by direct smear, culture or histopathological examination. Results: In this study, lymph node regression was found in 78% at the end of 2 months, 94% at the end of 4 months and 96% at the end of 6 months, 9 patients had regression in size though the nodes were palpable, 2 had no regression but fresh lymph nodes appeared on the same side and sinus discharge was present, culture was negative in these cases. Two cases had immune reconstitution syndrome, constitutional symptoms disappeared and showed clinical improvement. Four cases were subjected for surgical intervention. Conclusion: DOTS CAT III is effective in the treatment of tuberculous cervical lymphadenopathy. Compliance was good with minimal, minor side effects, only two had immune reconstitution syndrome and two had sinus formation; they were referred for

  19. Development of advanced direct perception displays for nuclear power plants to enhance monitoring, control and fault management

    Energy Technology Data Exchange (ETDEWEB)

    Jones, B.G.; Shaheen, S.; Moray, N. [and others

    1997-08-01

    Traditional Single-Sensor-Single Indicator (SSSI) displays are poorly matched to the cognitive abilities of operators, especially for large and complex systems. It is difficult for operators to monitor very large arrays of displays and controls, and to integrate the information displayed therein. In addition, standard operating procedures (SOPs) are bulky (running to many hundreds of pages) and difficult to use, and operators may become lost. For these reasons, and also because it is becoming increasingly difficult to find replacements for aging hardware components, there is a trend towards computerized graphical interfaces for nuclear power plants (NPPs). There is, however, little rational theory for display design in this domain. This report describes some recent theoretical developments and shows how to develop displays which will greatly reduce the cognitive load on the operator and allow the use of perceptual rather than cognitive mechanisms while using SON and to support state diagnosis and fault management. The report outlines the conceptual framework within which such a new approach could be developed, and provides an example of how the operating procedures for the start-up sequence of a NPP could be realized. A detailed description of a set of displays for a graphical interface for the SON of the feedwater system is provided as an example of how the proposed approach could be realized, and a general account of how it would fit into the overall start-up sequence is given. Examples of {open_quotes}direct perception{close_quotes} or {open_quotes}ecological{close_quotes} configural state space displays to support the use of the proposed direct manipulation SOP interface are provided, and also a critical discussion which identifies some difficulties which may be anticipated should the general approach herein advocated be adopted.

  20. Reduction of chronic abdominal pain in patients with inflammatory bowel disease through transcranial direct current stimulation: a randomized controlled trial.

    Science.gov (United States)

    Volz, Magdalena S; Farmer, Annabelle; Siegmund, Britta

    2016-02-01

    Inflammatory bowel disease (IBD) is frequently associated with chronic abdominal pain (CAP). Transcranial direct current stimulation (tDCS) has been proven to reduce chronic pain. This study aimed to investigate the effects of tDCS in patients with CAP due to IBD. This randomized, sham-controlled, double blind, parallel-designed study included 20 patients with either Crohn disease or ulcerative colitis with CAP (≥3/10 on the visual analog scale (VAS) in 3/6 months). Anodal or sham tDCS was applied over the primary motor cortex for 5 consecutive days (2 mA, 20 minutes). Assessments included VAS, pressure pain threshold, inflammatory markers, and questionnaires on quality of life, functional and disease specific symptoms (Irritable Bowel Syndrome-Severity Scoring System [IBS-SSS]), disease activity, and pain catastrophizing. Follow-up data were collected 1 week after the end of the stimulation. Statistical analyses were performed using analysis of variance and t tests. There was a significant reduction of abdominal pain in the anodal tDCS group compared with sham tDCS. This effect was evident in changes in VAS and pressure pain threshold on the left and right sides of the abdomen. In addition, 1 week after stimulation, pain reduction remained significantly decreased in the right side of the abdomen. There was also a significant reduction in scores on pain catastrophizing and on IBS-SSS when comparing both groups. Inflammatory markers and disease activity did not differ significantly between groups throughout the experiment. Transcranial direct current stimulation proved to be an effective and clinically relevant therapeutic strategy for CAP in IBD. The analgesic effects observed are unrelated to inflammation and disease activity, which emphasizes central pain mechanisms in CAP.