WorldWideScience

Sample records for cadherin-2 controls directional

  1. Entry: direct control or regulation?

    NARCIS (Netherlands)

    Perotti, E.; Vorage, M.

    2009-01-01

    We model a setting in which citizens form coalitions to seek preferential entry to a given market. The lower entry the higher firm profits and political contributions, but the lower social welfare. Politicians choose to either control entry directly and be illegally bribed, or regulate entry using a

  2. Direct Optimal Control of Duffing Dynamics

    Science.gov (United States)

    Oz, Hayrani; Ramsey, John K.

    2002-01-01

    The "direct control method" is a novel concept that is an attractive alternative and competitor to the differential-equation-based methods. The direct method is equally well applicable to nonlinear, linear, time-varying, and time-invariant systems. For all such systems, the method yields explicit closed-form control laws based on minimization of a quadratic control performance measure. We present an application of the direct method to the dynamics and optimal control of the Duffing system where the control performance measure is not restricted to a quadratic form and hence may include a quartic energy term. The results we present in this report also constitute further generalizations of our earlier work in "direct optimal control methodology." The approach is demonstrated for the optimal control of the Duffing equation with a softening nonlinear stiffness.

  3. Direct adaptive control using feedforward neural networks

    OpenAIRE

    Cajueiro, Daniel Oliveira; Hemerly, Elder Moreira

    2003-01-01

    ABSTRACT: This paper proposes a new scheme for direct neural adaptive control that works efficiently employing only one neural network, used for simultaneously identifying and controlling the plant. The idea behind this structure of adaptive control is to compensate the control input obtained by a conventional feedback controller. The neural network training process is carried out by using two different techniques: backpropagation and extended Kalman filter algorithm. Additionally, the conver...

  4. Multiparty-controlled quantum secure direct communication

    International Nuclear Information System (INIS)

    Xiu, X.-M.; Dong, L.; Gao, Y.-J.; Chi, F.

    2007-01-01

    A theoretical scheme of a multiparty-controlled quantum secure direct communication is proposed. The supervisor prepares a communication network with Einstein-Podolsky-Rosen pairs and auxiliary particles. After passing a security test of the communication network, a supervisor tells the users the network is secure and they can communicate. If the controllers allow the communicators to communicate, the controllers should perform measurements and inform the communicators of the outcomes. The communicators then begin to communicate after they perform a security test of the quantum channel and verify that it is secure. The recipient can decrypt the secret message in a classical message from the sender depending on the protocol. Any two users in the network can communicate through the above processes under the control of the supervisor and the controllers

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

    Science.gov (United States)

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

    2016-06-15

    Cadherins are crucial for the radial migration of excitatory projection neurons into the developing neocortical wall. However, the specific cadherins and the signaling pathways that regulate radial migration are not well understood. Here, we show that cadherin 2 (CDH2) and CDH4 cooperate to regulate radial migration in mouse brain via the protein tyrosine phosphatase 1B (PTP1B) and α- and β-catenins. Surprisingly, perturbation of cadherin-mediated signaling does not affect the formation and extension of leading processes of migrating neocortical neurons. Instead, movement of the cell body and nucleus (nucleokinesis) is disrupted. This defect is partially rescued by overexpression of LIS1, a microtubule-associated protein that has previously been shown to regulate nucleokinesis. Taken together, our findings indicate that cadherin-mediated signaling to the cytoskeleton is crucial for nucleokinesis of neocortical projection neurons during their radial migration. © 2016. Published by The Company of Biologists Ltd.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-05-15

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

  7. Directions for rf-controlled intelligent microvalve

    Science.gov (United States)

    Enderling, Stefan; Varadan, Vijay K.; Abbott, Derek

    2001-03-01

    In this paper, we consider the novel concept of a Radio Frequency (RF) controllable microvalve for different medical applications. Wireless communication via a Surface Acoustic Wave Identification-mark (SAW ID-tag) is used to control, drive and locate the microvalve inside the human body. The energy required for these functions is provided by RF pulses, which are transmitted to the valve and back by a reader/transmitter system outside of the body. These RF bursts are converted into Surface Acoustic Waves (SAWs), which propagate along the piezoelectric actuator material of the microvalve. These waves cause deflections, which are employed to open and close the microvalve. We identified five important areas of application of the microvalve in biomedicine: 1) fertility control; 2) artificial venous valves; 3) flow cytometry; 4) drug delivery and 5) DNA mapping.

  8. Optimal control novel directions and applications

    CERN Document Server

    Aronna, Maria; Kalise, Dante

    2017-01-01

    Focusing on applications to science and engineering, this book presents the results of the ITN-FP7 SADCO network’s innovative research in optimization and control in the following interconnected topics: optimality conditions in optimal control, dynamic programming approaches to optimal feedback synthesis and reachability analysis, and computational developments in model predictive control. The novelty of the book resides in the fact that it has been developed by early career researchers, providing a good balance between clarity and scientific rigor. Each chapter features an introduction addressed to PhD students and some original contributions aimed at specialist researchers. Requiring only a graduate mathematical background, the book is self-contained. It will be of particular interest to graduate and advanced undergraduate students, industrial practitioners and to senior scientists wishing to update their knowledge.

  9. 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 greatly...... from this technology because their low inertia. The paper proposes a operating procedure for utilizing DFCR loads for energy balancing, expanding DFCR’s well known role as a power balancing resource. The system operator can use DFCR for energy balancing by adjusting the frequency controller...... of generators to schedule off-nominal system frequency values. The feasibility of the proposed system is evaluated on an existing small island power system....

  10. Surface acoustic waves voltage controlled directional coupler

    Science.gov (United States)

    Golan, G.; Griffel, G.; Yanilov, E.; Ruschin, S.; Seidman, A.; Croitoru, N.

    1988-10-01

    An important condition for the development of surface wave integrated-acoustic devices is the ability to guide and control the propagation of the acoustic energy. This can be implemented by deposition of metallic "loading" channels on an anisotropic piezoelectric substrate. Deposition of such two parallel channels causes an effective coupling of acoustic energy from one channel to the other. A basic requirement for this coupling effect is the existence of the two basic modes: a symmetrical and a nonsymmetrical one. A mode map that shows the number of sustained modes as a function of the device parameters (i.e., channel width; distance between channels; material velocity; and acoustical exciting frequency) is presented. This kind of map can help significantly in the design process of such a device. In this paper we devise an advanced acoustical "Y" coupler with the ability to control its effective coupling by an externally applied voltage, thereby causing modulation of the output intensities of the signals.

  11. Topology Control in Aerial Multi-Beam Directional Networks

    Science.gov (United States)

    2017-04-24

    Topology Control in Aerial Multi-Beam Directional Networks Brian Proulx, Nathaniel M. Jones, Jennifer Madiedo, Greg Kuperman {brian.proulx, njones...significant interference. Topology control (i.e., selecting a subset of neighbors to communicate with) is vital to reduce the interference. Good topology ...underlying challenges to topology control in multi-beam direction networks. Two topology control algorithms are developed: a centralized algorithm

  12. Directional control-response compatibility of joystick steered shuttle cars.

    Science.gov (United States)

    Burgess-Limerick, Robin; Zupanc, Christine M; Wallis, Guy

    2012-01-01

    Shuttle cars are an unusual class of vehicle operated in underground coal mines, sometimes in close proximity to pedestrians and steering errors may have very serious consequences. A directional control-response incompatibility has previously been described in shuttle cars which are controlled using a steering wheel oriented perpendicular to the direction of travel. Some other shuttle car operators are seated perpendicular to the direction of travel and steer the car via a seat mounted joystick. A virtual simulation was utilised to determine whether the steering arrangement in these vehicles maintains directional control-response compatibility. Twenty-four participants were randomly assigned to either a condition corresponding to this design (consistent direction), or a condition in which the directional steering response was reversed while driving in-bye (visual field compatible). Significantly less accurate steering performance was exhibited by the consistent direction group during the in-bye trials only. Shuttle cars which provide the joystick steering mechanism described here require operators to accommodate alternating compatible and incompatible directional control-response relationships with each change of car direction. A virtual simulation of an underground coal shuttle car demonstrates that the design incorporates a directional control-response incompatibility when driving the vehicle in one direction. This design increases the probability of operator error, with potential adverse safety and productivity consequences.

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

    NARCIS (Netherlands)

    van den Beld, Wesley Theodorus Eduardus; van den Berg, 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

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

    International Nuclear Information System (INIS)

    Gao, T.

    2004-01-01

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

  15. 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 b...

  16. Direct adaptive control of manipulators in Cartesian space

    Science.gov (United States)

    Seraji, H.

    1987-01-01

    A new adaptive-control scheme for direct control of manipulator end effector to achieve trajectory tracking in Cartesian space is developed in this article. The control structure is obtained from linear multivariable theory and is composed of simple feedforward and feedback controllers and an auxiliary input. The direct adaptation laws are derived from model reference adaptive control theory and are not based on parameter estimation of the robot model. The utilization of adaptive feedforward control and the inclusion of auxiliary input are novel features of the present scheme and result in improved dynamic performance over existing adaptive control schemes. The adaptive controller does not require the complex mathematical model of the robot dynamics or any knowledge of the robot parameters or the payload, and is computationally fast for on-line implementation with high sampling rates. The control scheme is applied to a two-link manipulator for illustration.

  17. 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.

  18. Multiple Property Cross Direction Control of Paper Machines

    Directory of Open Access Journals (Sweden)

    Markku Ohenoja

    2011-07-01

    Full Text Available Cross direction (CD control in sheet-forming process forms a challenging problem with high dimensions. Accounting the interactions between different properties and actuators, the dimensionality increases further and also computational issues arise. We present a multiple property controller feasible to be used especially with imaging measurements that provide high sampling frequency and therefore enable short control interval. The simulation results state the benefits of multiple property CD control over single property control and single property control using full feedforward compensation. The controller presented may also be tuned in automated manner and the results demonstrate the effect of tuning on input saturation.

  19. Improving the performance of hysteresis direct torque control of ...

    Indian Academy of Sciences (India)

    Hysteresis direct torque control (HDTC) of an interior permanent magnet synchronous motor ... response, and improved the quality of the current waveforms. Luukko ..... LF , however, the cost and size of the AF increases, and therefore suitable ...

  20. 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...

  1. AmbiGaze : direct control of ambient devices by gaze

    OpenAIRE

    Velloso, Eduardo; Wirth, Markus; Weichel, Christian; Abreu Esteves, Augusto Emanuel; Gellersen, Hans-Werner Georg

    2016-01-01

    Eye tracking offers many opportunities for direct device control in smart environments, but issues such as the need for calibration and the Midas touch problem make it impractical. In this paper, we propose AmbiGaze, a smart environment that employs the animation of targets to provide users with direct control of devices by gaze only through smooth pursuit tracking. We propose a design space of means of exposing functionality through movement and illustrate the concept through four prototypes...

  2. Zener diode controls switching of large direct currents

    Science.gov (United States)

    1965-01-01

    High-current zener diode is connected in series with the positive input terminal of a dc supply to block the flow of direct current until a high-frequency control signal is applied across the zener diode. This circuit controls the switching of large dc signals.

  3. 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...

  4. Direct Model Reference Adaptive Control for a Magnetic Bearing

    Energy Technology Data Exchange (ETDEWEB)

    Durling, Mike [Rensselaer Polytechnic Inst., Troy, NY (United States)

    1999-11-01

    A Direct Model Reference Adaptive Controller (DMRAC) is applied to a magnetic bearing test stand. The bearing of interest is the MBC 500 Magnetic Bearing System manufactured by Magnetic Moments, LLC. The bearing model is presented in state space form and the system transfer function is measured directly using a closed-loop swept sine technique. Next, the bearing models are used to design a phase-lead controller, notch filter and then a DMRAC. The controllers are tuned in simulations and finally are implemented using a combination of MATLAB, SIMULINK and dSPACE. The results show a successful implementation of a DMRAC on the magnetic bearing hardware.

  5. Direct output feedback control of discrete-time systems

    International Nuclear Information System (INIS)

    Lin, C.C.; Chung, L.L.; Lu, K.H.

    1993-01-01

    An optimal direct output feedback control algorithm is developed for discrete-time systems with the consideration of time delay in control force action. Optimal constant output feedback gains are obtained through variational process such that certain prescribed quadratic performance index is minimized. Discrete-time control forces are then calculated from the multiplication of output measurements by these pre-calculated feedback gains. According to the proposed algorithm, structural system is assured to remain stable even in the presence of time delay. The number of sensors and controllers may be very small as compared with the dimension of states. Numerical results show that direct velocity feedback control is more sensitive to time delay than state feedback but, is still quite effective in reducing the dynamic responses under earthquake excitation. (author)

  6. Pixel extraction based integral imaging with controllable viewing direction

    International Nuclear Information System (INIS)

    Ji, Chao-Chao; Deng, Huan; Wang, Qiong-Hua

    2012-01-01

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

  7. 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...... robust stability analysis are presented. The sliding controller is compared with a linear DTC scheme, and experimental results for a sensorless IM drive validate the proposed solution....

  8. Direct adaptive control of a PUMA 560 industrial robot

    Science.gov (United States)

    Seraji, Homayoun; Lee, Thomas; Delpech, Michel

    1989-01-01

    The implementation and experimental validation of a new direct adaptive control scheme on a PUMA 560 industrial robot is described. The testbed facility consists of a Unimation PUMA 560 six-jointed robot and controller, and a DEC MicroVAX II computer which hosts the Robot Control C Library software. The control algorithm is implemented on the MicroVAX which acts as a digital controller for the PUMA robot, and the Unimation controller is effectively bypassed and used merely as an I/O device to interface the MicroVAX to the joint motors. The control algorithm for each robot joint consists of an auxiliary signal generated by a constant-gain Proportional plus Integral plus Derivative (PID) controller, and an adaptive position-velocity (PD) feedback controller with adjustable gains. The adaptive independent joint controllers compensate for the inter-joint couplings and achieve accurate trajectory tracking without the need for the complex dynamic model and parameter values of the robot. Extensive experimental results on PUMA joint control are presented to confirm the feasibility of the proposed scheme, in spite of strong interactions between joint motions. Experimental results validate the capabilities of the proposed control scheme. The control scheme is extremely simple and computationally very fast for concurrent processing with high sampling rates.

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

    Directory of Open Access Journals (Sweden)

    JAGADEESAN Karpagam

    2011-10-01

    Full Text Available This paper presents the Direct TorqueControl (DTC of induction motor drive using matrixconverters. DTC is a high performance motor controlscheme with fast torque and flux responses. However,the main disadvantage of conventional DTC iselectromagnetic torque ripple. In this paper, directtorque control for Induction Motors using MatrixConverters is analysed and points out the problem ofthe electromagnetic torque ripple which is one of themost important drawbacks of the Direct TorqueControl. Besides, the matrix converter is a single-stageac-ac power conversion device without dc-link energystorage elements. Matrix converter (MC may becomea good alternative to voltage-source inverter (VSI.This work combines the advantages of the matrixconverter with those of the DTC technique, generatingthe required voltage vectors under unity input powerfactor operation. Simulation results demonstrates theeffectiveness of the torque control.

  10. A Randomized Controlled Trial Comparing the Letter Project Advance Directive to Traditional Advance Directive.

    Science.gov (United States)

    Periyakoil, Vyjeyanthi S; Neri, Eric; Kraemer, Helena

    2017-09-01

    Simpler alternatives to traditional advance directives that are easy to understand and available in multiple formats and can be initiated by patients and families will help facilitate advance care planning. The goal of this study was to compare the acceptability of the letter advance directive (LAD) to the traditional advance directive (TAD) of the state of California. A web-based, randomized controlled trial was conducted, in which the participants were randomized to one of two types of advance directives (ADs): the LAD (intervention) or the TAD (control). Primary outcomes were participant ratings of the ease, value, and their level of comfort in the AD document they completed. A total of 400 participants completed the study, with 216 randomized to the LAD and 184 to the TAD by a computerized algorithm. Overall, participants preferred the LAD to the TAD (success rate difference [SRD] = 0.46, 95th percentile confidence interval [CI]: 0.36-0.56, p advance directive to be a better alternative to the traditional advance directive form.

  11. IPMSM Motion-Sensorless Direct Torque and Flux Control

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  12. Direct Torque Control With Feedback Linearization for Induction Motor Drives

    DEFF Research Database (Denmark)

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

    2017-01-01

    This paper describes a direct-torque-controlled (DTC) induction motor (IM) drive that employs feedback linearization and sliding-mode control (SMC). A new feedback linearization approach is proposed, 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 SMC with proportional control in the vicinity of the sliding surface. SMC assures...... in simulations. The sliding controller is compared with a linear DTC scheme with and without feedback linearization. Extensive experimental results for a sensorless IM drive validate the proposed solution....

  13. Stability analysis of direct current control in current source rectifier

    DEFF Research Database (Denmark)

    Lu, Dapeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    Current source rectifier with high switching frequency has a great potential for improving the power efficiency and power density in ac-dc power conversion. This paper analyzes the stability of direct current control based on the time delay effect. Small signal model including dynamic behaviors...

  14. 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…

  15. 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... title to 50 percent or more of the stock of the contractor or subcontractor is held subject to trust or...

  16. 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.

  17. Development of compact toroids injector for direct plasma controls

    Energy Technology Data Exchange (ETDEWEB)

    Azuma, K. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Oda, Y. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Onozuka, M. [Mitsubishi Heavy Industries Ltd., Takasago (Japan); Uyama, T. [Himeji Inst. of Tech. (Japan); Nagata, M. [Himeji Inst. of Tech. (Japan); Fukumoto, N. [Himeji Inst. of Tech. (Japan)

    1995-12-31

    The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 10{sup 21}m{sup -3}. (orig.).

  18. Development of compact toroids injector for direct plasma controls

    International Nuclear Information System (INIS)

    Azuma, K.; Oda, Y.; Onozuka, M.; Uyama, T.; Nagata, M.; Fukumoto, N.

    1995-01-01

    The application of the compact toroids injector for direct plasma controls has been investigated. The compact toroids injection can fuel particles directly into the core of the plasma and modify the plasma profiles at the desired locations. The acceleration tests of the compact toroids have been conducted at Himeji Institute of Technology. The tests showed that the hydrogen compact toroid was accelerated up to 80km/s and the plasma density of the compact toroid was compressed to 1.2 x 10 21 m -3 . (orig.)

  19. Quantum computation via local control theory: Direct sum vs. direct product Hilbert spaces

    International Nuclear Information System (INIS)

    Sklarz, Shlomo E.; Tannor, David J.

    2006-01-01

    The central objective in any quantum computation is the creation of a desired unitary transformation; the mapping that this unitary transformation produces between the input and output states is identified with the computation. In [S.E. Sklarz, D.J. Tannor, arXiv:quant-ph/0404081 (submitted to PRA) (2004)] it was shown that local control theory can be used to calculate fields that will produce such a desired unitary transformation. In contrast with previous strategies for quantum computing based on optimal control theory, the local control scheme maintains the system within the computational subspace at intermediate times, thereby avoiding unwanted decay processes. In [S.E. Sklarz et al.], the structure of the Hilbert space had a direct sum structure with respect to the computational register and the mediating states. In this paper, we extend the formalism to the important case of a direct product Hilbert space. The final equations for the control algorithm for the two cases are remarkably similar in structure, despite the fact that the derivations are completely different and that in one case the dynamics is in a Hilbert space and in the other case the dynamics is in a Liouville space. As shown in [S.E. Sklarz et al.], the direct sum implementation leads to a computational mechanism based on virtual transitions, and can be viewed as an extension of the principles of Stimulated Raman Adiabatic Passage from state manipulation to evolution operator manipulation. The direct product implementation developed here leads to the intriguing concept of virtual entanglement - computation that exploits second-order transitions that pass through entangled states but that leaves the subsystems nearly separable at all intermediate times. Finally, we speculate on a connection between the algorithm developed here and the concept of decoherence free subspaces

  20. Thrust and jet directional control using the Coanda effect

    Directory of Open Access Journals (Sweden)

    Alexandru DUMITRACHE

    2018-06-01

    Full Text Available The application of the Coandă effect to the directional control of a jet or thrust is presented. Deviation of the thrust force by direct flow can be achieved by using the Coandă effect to change the angle of the primary jet engine exhaust nozzle. Major interest in the study of this phenomenon is caused by the possibility of using this effect for aircrafts with short take-off and landing, for thrust vectoring. The numerical investigations are performed using a RANS solver with an adequate turbulence model, showing a change of the jet direction. Thus, the conditions and the limits within which one can benefit from the advantages of Coandă-type flows are determined.

  1. 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.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    A predictive control using subspace identification is applied for the smart grid integration of refrigeration systems under a direct load control scheme. A realistic demand response scenario based on regulation of the electrical power consumption is considered. A receding horizon optimal control...... is proposed to fulfil two important objectives: to secure high coefficient of performance and to participate in power consumption management. Moreover, a new method for design of input signals for system identification is put forward. The control method is fully data driven without an explicit use of model...... against real data. The performance improvement results in a 22% reduction in the energy consumption. A comparative simulation is accomplished showing the superiority of the method over the existing approaches in terms of the load following performance....

  3. Direct Energy Centre underground parking integrated light control system

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-10-15

    LightSavers is a project undertaken by the Toronto Atmospheric Fund to accelerate the use of lighting technologies. As part of the project a pilot test has been carried out in the Direct Energy Center in Toronto. The aim of this report is to present the study and its results. The Direct Energy Center is a large event facility with an large underground parking facility. A lighting energy management system, the energy control system (ECS), capable of adjusting lighting levels based on occupancy was implemented in the centre and data was collected during over one year. Results showed that the ECS permitted a reduction in energy consumption and thus greenhouse gas emissions by 47% and the payback will take less than 6 years. This project demonstrated that the energy control system provides better energy, environmental and economic performance than a traditional automation system.

  4. Direct harmonic voltage control strategy for shunt active power filter

    DEFF Research Database (Denmark)

    Munir, Hafiz Mudassir; Zou, JianXiao; Xie, Chuan

    2017-01-01

    generation system (DPGS) where the nonlinear loads are highly dispersed. Local harmonic voltage detection based Resistive-APF (R-APF) seems more suitable to be applied in the DPGS, however, R-APF suffers from poor compensation performance and difficulty of parameter tuning. In this paper, a direct harmonic...... voltage control strategy for the S-APF is proposed with local point of common coupling (PCC) voltage detection only. The control strategy design procedure is given in detail. Simulation is conducted in Matlab/Simulink to compare the performance between the R-APF and the proposed method. The results...

  5. Information Modeling for Direct Control of Distributed Energy Resources

    DEFF Research Database (Denmark)

    Biegel, Benjamin; Andersen, Palle; Stoustrup, Jakob

    2013-01-01

    We present an architecture for an unbundled liberalized electricity market system where a virtual power plant (VPP) is able to control a number of distributed energy resources (DERs) directly through a two-way communication link. The aggregator who operates the VPP utilizes the accumulated...... 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...

  6. Subfemtosecond directional control of chemical processes in molecules

    Science.gov (United States)

    Alnaser, Ali S.; Litvinyuk, Igor V.

    2017-02-01

    Laser pulses with a waveform-controlled electric field and broken inversion symmetry establish the opportunity to achieve directional control of molecular processes on a subfemtosecond timescale. Several techniques could be used to break the inversion symmetry of an electric field. The most common ones include combining a fundamental laser frequency with its second harmonic or with higher -frequency pulses (or pulse trains) as well as using few-cycle pulses with known carrier-envelope phase (CEP). In the case of CEP, control over chemical transformations, typically occurring on a timescale of many femtoseconds, is driven by much faster sub-cycle processes of subfemtosecond to few-femtosecond duration. This is possible because electrons are much lighter than nuclei and fast electron motion is coupled to the much slower nuclear motion. The control originates from populating coherent superpositions of different electronic or vibrational states with relative phases that are dependent on the CEP or phase offset between components of a two-color pulse. In this paper, we review the recent progress made in the directional control over chemical processes, driven by intense few-cycle laser pulses a of waveform-tailored electric field, in different molecules.

  7. Directed Assembly of Janus Cylinders by Controlling the Solvent Polarity.

    Science.gov (United States)

    Kim, Jongmin; Choi, Chang-Hyung; Yeom, Su-Jin; Eom, Naye; Kang, Kyoung-Ku; Lee, Chang-Soo

    2017-08-01

    This study demonstrates the possibility of controlling the directed self-assembly of microsized Janus cylinders by changing the solvent polarity of the assembly media. Experimental results are analyzed and theoretical calculations of the free energy of adhesion (ΔG ad ) are performed to elucidate the underlying basic principles and investigate the effects of the solvent on the self-assembled structures. This approach will pave a predictive route for controlling the structures of assembly depending on the solvent polarity. In particular, we find that a binary solvent system with precisely controlled polarity induces directional assembly of the microsized Janus cylinders. Thus, the formation of two-dimensional (2D) and three-dimensional (3D) assembled clusters can be reliably tuned by controlling the numbers of constituent Janus cylinders in a binary solvent system. Finally, this approach is expanded to stepwise assembly, which forms unique microstructures via secondary growth of primary seed clusters formed by the Janus cylinders. We envision that this investigation is highly promising for the construction of desired superstructures using a wide variety of polymeric Janus microparticles with chemical and physical multicompartments.

  8. 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).

  9. Control concepts for direct steam generation in parabolic troughs

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-02-01

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

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

    International Nuclear Information System (INIS)

    Wang, Bingbo; Gao, Lin; Gao, Yong

    2012-01-01

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

  11. 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.

  12. Decentralized adaptive control of interconnected nonlinear systems with unknown control directions.

    Science.gov (United States)

    Huang, Jiangshuai; Wang, Qing-Guo

    2018-03-01

    In this paper, we propose a decentralized adaptive control scheme for a class of interconnected strict-feedback nonlinear systems without a priori knowledge of subsystems' control directions. To address this problem, a novel Nussbaum-type function is proposed and a key theorem is drawn which involves quantifying the interconnections of multiple Nussbaum-type functions of the subsystems with different control directions in a single inequality. Global stability of the closed-loop system and asymptotic stabilization of subsystems' output are proved and a simulation example is given to illustrate the effectiveness of the proposed control scheme. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  13. Direct model reference adaptive control with application to flexible robots

    Science.gov (United States)

    Steinvorth, Rodrigo; Kaufman, Howard; Neat, Gregory W.

    1992-01-01

    A modification to a direct command generator tracker-based model reference adaptive control (MRAC) system is suggested in this paper. This modification incorporates a feedforward into the reference model's output as well as the plant's output. Its purpose is to eliminate the bounded model following error present in steady state when previous MRAC systems were used. The algorithm was evaluated using the dynamics for a single-link flexible-joint arm. The results of these simulations show a response with zero steady state model following error. These results encourage further use of MRAC for various types of nonlinear plants.

  14. Controlling chaos-assisted directed transport via quantum resonance.

    Science.gov (United States)

    Tan, Jintao; Zou, Mingliang; Luo, Yunrong; Hai, Wenhua

    2016-06-01

    We report on the first demonstration of chaos-assisted directed transport of a quantum particle held in an amplitude-modulated and tilted optical lattice, through a resonance-induced double-mean displacement relating to the true classically chaotic orbits. The transport velocity is controlled by the driving amplitude and the sign of tilt, and also depends on the phase of the initial state. The chaos-assisted transport feature can be verified experimentally by using a source of single atoms to detect the double-mean displacement one by one, and can be extended to different scientific fields.

  15. Controlling chaos-assisted directed transport via quantum resonance

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Jintao; Zou, Mingliang; Luo, Yunrong; Hai, Wenhua, E-mail: whhai2005@aliyun.com [Department of Physics and Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha 410081, China and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha 410081 (China)

    2016-06-15

    We report on the first demonstration of chaos-assisted directed transport of a quantum particle held in an amplitude-modulated and tilted optical lattice, through a resonance-induced double-mean displacement relating to the true classically chaotic orbits. The transport velocity is controlled by the driving amplitude and the sign of tilt, and also depends on the phase of the initial state. The chaos-assisted transport feature can be verified experimentally by using a source of single atoms to detect the double-mean displacement one by one, and can be extended to different scientific fields.

  16. 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.

  17. Direct emission of chirality controllable femtosecond LG01 vortex beam

    Science.gov (United States)

    Wang, S.; Zhang, S.; Yang, H.; Xie, J.; Jiang, S.; Feng, G.; Zhou, S.

    2018-05-01

    Direct emission of a chirality controllable ultrafast LG01 mode vortex optical beam from a conventional z-type cavity design SESAM (SEmiconductor Saturable Absorber Mirror) mode locked LD pumped Yb:Phosphate laser has been demonstrated. A clean 360 fs vortex beam of ˜45.7 mW output power has been achieved. A radial shear interferometer has been built to determine the phase singularity and the wavefront helicity of the ultrafast output laser. Theoretically, it is found that the LG01 vortex beam is obtained via the combination effect of diagonal HG10 mode generation by off-axis pumping and the controllable Gouy phase difference between HG10 and HG01 modes in the sagittal and tangential planes. The chirality of the LG01 mode can be manipulated by the pump position to the original point of the laser cavity optical axis.

  18. Direct digital control of furnaces irradiated in nuclear reactors

    International Nuclear Information System (INIS)

    Joumard, R.

    1969-01-01

    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) [fr

  19. Construction and direct electrochemistry of orientation controlled laccase electrode.

    Science.gov (United States)

    Li, Ying; Zhang, Jiwei; Huang, Xirong; Wang, Tianhong

    2014-03-28

    A laccase has multiple redox centres. Chemisorption of laccases on a gold electrode through a polypeptide tag introduced at the protein surface provides an isotropic orientation of laccases on the Au surface, which allows the orientation dependent study of the direct electrochemistry of laccase. In this paper, using genetic engineering technology, two forms of recombinant laccase which has Cys-6×His tag at the N or C terminus were generated. Via the Au-S linkage, the recombinant laccase was assembled orientationally on gold electrode. A direct electron transfer and a bioelectrocatalytic activity toward oxygen reduction were observed on the two orientation controlled laccase electrodes, but their electrochemical behaviors were found to be quite different. The orientation of laccase on the gold electrode affects both the electron transfer pathway and the electron transfer efficiency of O2 reduction. The present study is helpful not only to the in-depth understanding of the direct electrochemistry of laccase, but also to the development of laccase-based biofuel cells. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Design method for marine direct drive volume control ahead actuator

    Directory of Open Access Journals (Sweden)

    WANG Haiyang

    2018-02-01

    Full Text Available [Objectives] In order to reduce the size, weight and auxiliary system configuration of marine ahead actuators, this paper proposes a kind of direct drive volume control electro-hydraulic servo ahead actuator. [Methods] The protruding and indenting control of the servo oil cylinder are realized through the forward and reverse of the bidirectional working gear pump, and the flow matching valve implements the self-locking of the ahead actuator in the target position. The mathematical model of the ahead actuator is established, and an integral separation fuzzy PID controller designed. On this basis, using AMESim software to build a simulation model of the ahead actuator, and combined with testing, this paper completes an analysis of the control strategy research and dynamic and static performance of the ahead actuator. [Results] The experimental results agree well with the simulation results and verify the feasibility of the ahead actuator's design. [Conclusions] The research results of this paper can provide valuable references for the integration and miniaturization design of marine ahead actuators.

  1. Direct numerical simulation of vector-controlled free jets

    International Nuclear Information System (INIS)

    Tsujimoto, K; Ao, K; Shakouchi, T; Ando, T

    2011-01-01

    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.

  2. 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...

  3. Comparison between iterative wavefront control algorithm and direct gradient wavefront control algorithm for adaptive optics system

    International Nuclear Information System (INIS)

    Cheng Sheng-Yi; Liu Wen-Jin; Chen Shan-Qiu; Dong Li-Zhi; Yang Ping; Xu Bing

    2015-01-01

    Among all kinds of wavefront control algorithms in adaptive optics systems, the direct gradient wavefront control algorithm is the most widespread and common method. This control algorithm obtains the actuator voltages directly from wavefront slopes through pre-measuring the relational matrix between deformable mirror actuators and Hartmann wavefront sensor with perfect real-time characteristic and stability. However, with increasing the number of sub-apertures in wavefront sensor and deformable mirror actuators of adaptive optics systems, the matrix operation in direct gradient algorithm takes too much time, which becomes a major factor influencing control effect of adaptive optics systems. In this paper we apply an iterative wavefront control algorithm to high-resolution adaptive optics systems, in which the voltages of each actuator are obtained through iteration arithmetic, which gains great advantage in calculation and storage. For AO system with thousands of actuators, the computational complexity estimate is about O(n 2 ) ∼ O(n 3 ) in direct gradient wavefront control algorithm, while the computational complexity estimate in iterative wavefront control algorithm is about O(n) ∼ (O(n) 3/2 ), in which n is the number of actuators of AO system. And the more the numbers of sub-apertures and deformable mirror actuators, the more significant advantage the iterative wavefront control algorithm exhibits. (paper)

  4. Electric Vehicle Longitudinal Stability Control Based on a New Multimachine Nonlinear Model Predictive Direct Torque Control

    Directory of Open Access Journals (Sweden)

    M’hamed Sekour

    2017-01-01

    Full Text Available In order to improve the driving performance and the stability of electric vehicles (EVs, a new multimachine robust control, which realizes the acceleration slip regulation (ASR and antilock braking system (ABS functions, based on nonlinear model predictive (NMP direct torque control (DTC, is proposed for four permanent magnet synchronous in-wheel motors. The in-wheel motor provides more possibilities of wheel control. One of its advantages is that it has low response time and almost instantaneous torque generation. Moreover, it can be independently controlled, enhancing the limits of vehicular control. For an EV equipped with four in-wheel electric motors, an advanced control may be envisaged. Taking advantage of the fast and accurate torque of in-wheel electric motors which is directly transmitted to the wheels, a new approach for longitudinal control realized by ASR and ABS is presented in this paper. In order to achieve a high-performance torque control for EVs, the NMP-DTC strategy is proposed. It uses the fuzzy logic control technique that determines online the accurate values of the weighting factors and generates the optimal switching states that optimize the EV drives’ decision. The simulation results built in Matlab/Simulink indicate that the EV can achieve high-performance vehicle longitudinal stability control.

  5. Comparison between iterative wavefront control algorithm and direct gradient wavefront control algorithm for adaptive optics system

    Science.gov (United States)

    Cheng, Sheng-Yi; Liu, Wen-Jin; Chen, Shan-Qiu; Dong, Li-Zhi; Yang, Ping; Xu, Bing

    2015-08-01

    Among all kinds of wavefront control algorithms in adaptive optics systems, the direct gradient wavefront control algorithm is the most widespread and common method. This control algorithm obtains the actuator voltages directly from wavefront slopes through pre-measuring the relational matrix between deformable mirror actuators and Hartmann wavefront sensor with perfect real-time characteristic and stability. However, with increasing the number of sub-apertures in wavefront sensor and deformable mirror actuators of adaptive optics systems, the matrix operation in direct gradient algorithm takes too much time, which becomes a major factor influencing control effect of adaptive optics systems. In this paper we apply an iterative wavefront control algorithm to high-resolution adaptive optics systems, in which the voltages of each actuator are obtained through iteration arithmetic, which gains great advantage in calculation and storage. For AO system with thousands of actuators, the computational complexity estimate is about O(n2) ˜ O(n3) in direct gradient wavefront control algorithm, while the computational complexity estimate in iterative wavefront control algorithm is about O(n) ˜ (O(n)3/2), in which n is the number of actuators of AO system. And the more the numbers of sub-apertures and deformable mirror actuators, the more significant advantage the iterative wavefront control algorithm exhibits. Project supported by the National Key Scientific and Research Equipment Development Project of China (Grant No. ZDYZ2013-2), the National Natural Science Foundation of China (Grant No. 11173008), and the Sichuan Provincial Outstanding Youth Academic Technology Leaders Program, China (Grant No. 2012JQ0012).

  6. Offset-Free Direct Power Control of DFIG Under Continuous-Time Model Predictive Control

    DEFF Research Database (Denmark)

    Errouissi, Rachid; Al-Durra, Ahmed; Muyeen, S.M.

    2017-01-01

    This paper presents a robust continuous-time model predictive direct power control for doubly fed induction generator (DFIG). The proposed approach uses Taylor series expansion to predict the stator current in the synchronous reference frame over a finite time horizon. The predicted stator current...... is directly used to compute the required rotor voltage in order to minimize the difference between the actual stator currents and their references over the predictive time. However, as the proposed strategy is sensitive to parameter variations and external disturbances, a disturbance observer is embedded...... into the control loop to remove the steady-state error of the stator current. It turns out that the steady-state and the transient performances can be identified by simple design parameters. In this paper, the reference of the stator current is directly calculated from the desired stator active and reactive powers...

  7. Cerebellar transcranial direct current stimulation improves adaptive postural control.

    Science.gov (United States)

    Poortvliet, Peter; Hsieh, Billie; Cresswell, Andrew; Au, Jacky; Meinzer, Marcus

    2018-01-01

    Rehabilitation interventions contribute to recovery of impaired postural control, but it remains a priority to optimize their effectiveness. A promising strategy may involve transcranial direct current stimulation (tDCS) of brain areas involved in fine-tuning of motor adaptation. This study explored the effects of cerebellar tDCS (ctDCS) on postural recovery from disturbance by Achilles tendon vibration. Twenty-eight healthy volunteers participated in this sham-ctDCS controlled study. Standing blindfolded on a force platform, four trials were completed: 60 s quiet standing followed by 20 min active (anodal-tDCS, 1 mA, 20 min, N = 14) or sham-ctDCS (40 s, N = 14) tDCS; three quiet standing trials with 15 s of Achilles tendon vibration and 25 s of postural recovery. Postural steadiness was quantified as displacement, standard deviation and path derived from the center of pressure (COP). Baseline demographics and quiet standing postural steadiness, and backwards displacement during vibration were comparable between groups. However, active-tDCS significantly improved postural steadiness during vibration and reduced forward displacement and variability in COP derivatives during recovery. We demonstrate that ctDCS results in short-term improvement of postural adaptation in healthy individuals. Future studies need to investigate if multisession ctDCS combined with training or rehabilitation interventions can induce prolonged improvement of postural balance. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  8. Direct observation, study and control of molecular super rotors

    Science.gov (United States)

    Korobenko, Aleksey; Milner, Alexander; Hepburn, John; Milner, Valery

    2014-05-01

    Extremely fast rotating molecules whose rotational energy is comparable with or exceeds the molecular bond strength are known as ``super rotors''. It has been speculated that super rotors may exhibit a number of unique properties, yet only indirect evidence of these molecular objects has been reported to date. We demonstrate the first direct observation of molecular super rotors by detecting coherent unidirectional molecular rotation with extreme frequencies exceeding 10 THz. The technique of an ``optical centrifuge'' is used to control the degree of rotational excitation in an ultra-broad range of rotational quantum numbers, reaching as high as N = 95 in oxygen and N = 60 in nitrogen. State-resolved detection enables us to determine the shape of the excited rotational wave packet and quantify the effect of centrifugal distortion on the rotational spectrum. Femtosecond time resolution reveals coherent rotational dynamics with increasing coherence times at higher angular momentum. We demonstrate that molecular super rotors can be created and observed in dense samples under normal conditions where the effects of ultrafast rotation on many-body interactions, inter-molecular collisions and chemical reactions can be readily explored.

  9. Cholinergic neuromodulation controls directed temporal communication in neocortex in vitro

    Directory of Open Access Journals (Sweden)

    Anita K Roopun

    2010-03-01

    Full Text Available Acetylcholine is the primary neuromodulator involved in cortical arousal in mammals. Cholinergic modulation is involved in conscious awareness, memory formation and attention – processes that involve intercommunication between different cortical regions. Such communication is achieved in part through temporal structuring of neuronal activity by population rhythms, particularly in the beta and gamma frequency ranges (12 – 80 Hz. Here we demonstrate, using in vitro and in silico models, that spectrally identical patterns of beta2 and gamma rhythms are generated in primary sensory areas and polymodal association areas by fundamentally different local circuit mechanisms: Glutamatergic excitation induced beta2 frequency population rhythms only in layer 5 association cortex whereas cholinergic neuromodulation induced this rhythm only in layer 5 primary sensory cortex. This region-specific sensitivity of local circuits to cholinergic modulation allowed for control of the extent of cortical temporal interactions. Furthermore, the contrasting mechanisms underlying these beta2 rhythms produced a high degree of directionality, favouring an influence of association cortex over primary auditory cortex.

  10. Cholinergic Neuromodulation Controls Directed Temporal Communication in Neocortex in Vitro

    Science.gov (United States)

    Roopun, Anita K.; LeBeau, Fiona E.N.; Rammell, James; Cunningham, Mark O.; Traub, Roger D.; Whittington, Miles A.

    2010-01-01

    Acetylcholine is the primary neuromodulator involved in cortical arousal in mammals. Cholinergic modulation is involved in conscious awareness, memory formation and attention – processes that involve intercommunication between different cortical regions. Such communication is achieved in part through temporal structuring of neuronal activity by population rhythms, particularly in the beta and gamma frequency ranges (12–80 Hz). Here we demonstrate, using in vitro and in silico models, that spectrally identical patterns of beta2 and gamma rhythms are generated in primary sensory areas and polymodal association areas by fundamentally different local circuit mechanisms: Glutamatergic excitation induced beta2 frequency population rhythms only in layer 5 association cortex whereas cholinergic neuromodulation induced this rhythm only in layer 5 primary sensory cortex. This region-specific sensitivity of local circuits to cholinergic modulation allowed for control of the extent of cortical temporal interactions. Furthermore, the contrasting mechanisms underlying these beta2 rhythms produced a high degree of directionality, favouring an influence of association cortex over primary auditory cortex. PMID:20407636

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

    International Nuclear Information System (INIS)

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

    2006-01-01

    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 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

  12. Habitual versus goal-directed action control in Parkinson disease.

    Science.gov (United States)

    de Wit, Sanne; Barker, Roger A; Dickinson, Anthony D; Cools, Roshan

    2011-05-01

    This study presents the first direct investigation of the hypothesis that dopamine depletion of the dorsal striatum in mild Parkinson disease leads to impaired stimulus-response habit formation, thereby rendering behavior slow and effortful. However, using an instrumental conflict task, we show that patients are able to rely on direct stimulus-response associations when a goal-directed strategy causes response conflict, suggesting that habit formation is not impaired. If anything our results suggest a disease severity-dependent deficit in goal-directed behavior. These results are discussed in the context of Parkinson disease and the neurobiology of habitual and goal-directed behavior.

  13. Sleep Deprivation Promotes Habitual Control over Goal-Directed Control: Behavioral and Neuroimaging Evidence.

    Science.gov (United States)

    Chen, Jie; Liang, Jie; Lin, Xiao; Zhang, Yang; Zhang, Yan; Lu, Lin; Shi, Jie

    2017-12-06

    Sleep is one of the most fundamental processes of life, playing an important role in the regulation of brain function. The long-term lack of sleep can cause memory impairments, declines in learning ability, and executive dysfunction. In the present study, we evaluated the effects of sleep deprivation on instrumental learning behavior, particularly goal-directed and habitual actions in humans, and investigated the underlying neural mechanisms. Healthy college students of either gender were enrolled and randomly divided into sleep deprivation group and sleep control group. fMRI data were collected. We found that one night of sleep deprivation led to greater responsiveness to stimuli that were associated with devalued outcomes in the slips-of-action test, indicating a deficit in the formation of goal-directed control and an overreliance on habits. Furthermore, sleep deprivation had no effect on the expression of acquired goal-directed action. The level of goal-directed action after sleep deprivation was positively correlated with baseline working memory capacity. The neuroimaging data indicated that goal-directed learning mainly recruited the ventromedial PFC (vmPFC), the activation of which was less pronounced during goal-directed learning after sleep deprivation. Activation of the vmPFC during goal-directed learning during training was positively correlated with the level of goal-directed action performance. The present study suggests that people rely predominantly on habits at the expense of goal-directed control after sleep deprivation, and this process involves the vmPFC. These results contribute to a better understanding of the effects of sleep loss on decision-making. SIGNIFICANCE STATEMENT Understanding the cognitive consequences of sleep deprivation has become extremely important over the past half century, given the continued decline in sleep duration in industrialized societies. Our results provide novel evidence that goal-directed action may be

  14. 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.

  15. Direct digital temperature control of the A-1 nuclear reactor

    International Nuclear Information System (INIS)

    Karpeta, C.

    1975-01-01

    The application is described of one of the modern control methods for designing an experimental digital temperature control system for heavy water moderated gas cooled reactors. The synthesis of the optimal stochastic regulator for reactor control in the area of the rated steady state was carried out using the method of dynamic programming and the Kalman filter technique. The analysis of the feedback circuit was conducted using control simulation on a universal digital computer. Results and experience are summed up. (author)

  16. 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...

  17. Direct Digital Control of HVAC (Heating, Ventilating, and Air Conditioning).

    Science.gov (United States)

    1985-01-01

    controller func- tions such as time-of-day, economizer cycles, reset, load shedding, chiller optimization , VAV fan synchronization, and optimum start/stop...control system such as that illustrated in Fig- urc 4. Data on setpoints , reset schedules, and event timing, such as that presented in Figure 6, are...program code (Figure 7). In addition to the control logic, setpoint and other data are readily available. Program logi:, setpoint and schedule data, and

  18. Experimentally supported control design for a direct drive robot

    NARCIS (Netherlands)

    Kostic, D.; Jager, de A.G.; Steinbuch, M.

    2002-01-01

    We promote the idea of an experimentally supported control design as a successful way to achieve accurate tracking of reference robot motions, under disturbance conditions and given the uncertainties arising from modeling errors. The Hinf robust control theory is used for design of motion

  19. Combustion control for diesel engines with direct injection

    Energy Technology Data Exchange (ETDEWEB)

    Jeschke, J.; Henn, M.; Lang, T.; Wendt, J.; Nitzke, H.G.; Mannigel, D. [Volkswagen AG (Germany)

    2007-07-01

    This article looks at a new cylinder pressure-based combustion control for DI diesel engines that has been developed by Volkswagen. This cylinder pressure-based control uses cylinder pressure sensors that are integrated in the glow plugs. The description and the evaluation of these sensors form a main part of this article as they are a central element in the new diesel management system. The test and development phase in connection with a rapid prototyping system and the realisation of the combustion control algorithms in a diesel control unit are also described. Finally, results from use of the closed-loop combustion control with different applications on a diesel engine are presented. (orig.)

  20. Dynamic access control for two-direction shared traffic lanes

    NARCIS (Netherlands)

    Ebben, Mark; van der Zee, D.J.; van der Heijden, Matthijs C.

    2001-01-01

    In specific traffic situations, a single lane is available for traffic from two directions. Examples are traffic accidents or road maintenance reducing the number of available lanes on a road or, as we faced in a project on underground freight transportation, construction of a single lane for two

  1. Dynamic access control for two-direction shared traffic lanes

    NARCIS (Netherlands)

    Ebben, M.J.R.; van der Zee, D.J.; van der Heijden, M.C.

    2000-01-01

    In specilic traflic situations, a single lane is available for traiffic from two directions. Examples are traffic accidents or road maintenance reducing thc number of available lanes on a road or, as we faced in a project on underground freight transportation, construction of a slnglc lane for two

  2. Habitual versus goal-directed action control in Parkinson disease

    NARCIS (Netherlands)

    de Wit, S.; Barker, R.A.; Dickinson, A.D.; Cools, R.

    2011-01-01

    This study presents the first direct investigation of the hypothesis that dopamine depletion of the dorsal striatum in mild Parkinson disease leads to impaired stimulus-response habit formation, thereby rendering behavior slow and effortful. However, using an instrumental conflict task, we show that

  3. A direct digital controller for an automatic sodium plugging meter

    International Nuclear Information System (INIS)

    Tobias, A.

    1977-07-01

    A plugging meter is a device for monitoring the impurity level of liquid sodium. It is used to measure the temperature at which an impurity precipitates or re-dissolves at a restricting orifice. The concentration of the impurity may be then deduced from known solubility/temperature relationships. A software controller for a sodium plugging meter has been implemented on a PDP-11 using SWEPSPEED. The algorithm used to perform both flow and temperature control functions is based on a modified standard three-term controller. Both design and operation of the controller are described. The functions which may be performed by the controller are: (i) maintain a steady temperature at the restricting orifice, (ii) perform a temperature ramp at a rate defined by the operator, and (iii) maintain a partial plug of impurities at the orifice by appropriate manipulation of the temperature. Accuracies so far achieved are approximately +- 5% for flow control and better that +- 1 0 C for temperature control. (author)

  4. 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.

  5. QuickDirect - Payload Control Software Template Package, Phase I

    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...

  6. 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.

  7. 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...

  8. Three omni-directional wheels control on a mobile robot

    OpenAIRE

    Ribeiro, António Fernando; Moutinho, Ivo; Silva, Pedro; Fraga, Carlos; Pereira, Nino

    2004-01-01

    Traditional two wheels differential drive normally used on mobile robots have manoeuvrability limitations and take time to sort out. Most teams use two driving wheels (with one or two cast wheels), four driving wheels and even three driving wheels. A three wheel drive with omni-directional wheel has been tried with success, and was implemented on fast moving autonomous mobile robots. This paper deals with the mathematical kinematics description of such mobile platform, it describes the advant...

  9. Chained Iron Microparticles for Directionally Controlled Actuation of Soft Robots.

    Science.gov (United States)

    Schmauch, Marissa M; Mishra, Sumeet R; Evans, Benjamin A; Velev, Orlin D; Tracy, Joseph B

    2017-04-05

    Magnetic field-directed self-assembly of magnetic particles in chains is useful for developing directionally responsive materials for applications in soft robotics. Using materials with greater complexity allows advanced functions, while still using simple device architectures. Elastomer films containing chained magnetic microparticles were prepared through solvent casting and formed into magnetically actuated lifters, accordions, valves, and pumps. Chaining both enhances actuation and imparts a directional response. Cantilevers used as lifters were able to lift up to 50 times the mass of the polymer film. We introduce the "specific torque", the torque per field per mass of magnetic particles, as a figure of merit for assessing and comparing the performance of lifters and related devices. Devices in this work generated specific torques of 68 Nm/kgT, which is significantly higher than in previously reported actuators. Applying magnetic fields to folded accordion structures caused extension and compression, depending on the accordion's orientation. In peristaltic pumps comprised of composite tubes containing embedded chains, magnetic fields caused a section of the tube to pinch closed where the field was applied. These results will facilitate both the further development of soft robots based on chained magnetic particles and efforts to engineer materials with higher specific torque.

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

    Science.gov (United States)

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

    2002-01-01

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

  11. The perceptual control of goal-directed locomotion: a common control architecture for interception and navigation?

    Science.gov (United States)

    Chardenon, A; Montagne, G; Laurent, M; Bootsma, R J

    2004-09-01

    Intercepting a moving object while locomoting is a highly complex and demanding ability. Notwithstanding the identification of several informational candidates, the role of perceptual variables in the control process underlying such skills remains an open question. In this study we used a virtual reality set-up for studying locomotor interception of a moving ball. The subject had to walk along a straight path and could freely modify forward velocity, if necessary, in order to intercept-with the head-a ball moving along a straight path that led it to cross the agent's displacement axis. In a series of experiments we manipulated a local (ball size) and a global (focus of expansion) component of the visual flow but also the egocentric orientation of the ball. The experimental observations are well captured by a dynamic model linking the locomotor acceleration to properties of both global flow and egocentric direction. More precisely the changes in locomotor velocity depend on a linear combination of the change in bearing angle and the change in egocentric orientation, allowing the emergence of adaptive behavior under a variety of circumstances. We conclude that the mechanisms underlying the control of different goal-directed locomotion tasks (i.e. steering and interceptive tasks) could share a common architecture.

  12. Controlling Water Intercalation Is Key to a Direct Graphene Transfer.

    Science.gov (United States)

    Verguts, Ken; Schouteden, Koen; Wu, Cheng-Han; Peters, Lisanne; Vrancken, Nandi; Wu, Xiangyu; Li, Zhe; Erkens, Maksiem; Porret, Clement; Huyghebaert, Cedric; Van Haesendonck, Chris; De Gendt, Stefan; Brems, Steven

    2017-10-25

    The key steps of a transfer of two-dimensional (2D) materials are the delamination of the as-grown material from a growth substrate and the lamination of the 2D material on a target substrate. In state-of-the-art transfer experiments, these steps remain very challenging, and transfer variations often result in unreliable 2D material properties. Here, it is demonstrated that interfacial water can insert between graphene and its growth substrate despite the hydrophobic behavior of graphene. It is understood that interfacial water is essential for an electrochemistry-based graphene delamination from a Pt surface. Additionally, the lamination of graphene to a target wafer is hindered by intercalation effects, which can even result in graphene delamination from the target wafer. For circumvention of these issues, a direct, support-free graphene transfer process is demonstrated, which relies on the formation of interfacial water between graphene and its growth surface, while avoiding water intercalation between graphene and the target wafer by using hydrophobic silane layers on the target wafer. The proposed direct graphene transfer also avoids polymer contamination (no temporary support layer) and eliminates the need for etching of the catalyst metal. Therefore, recycling of the growth template becomes feasible. The proposed transfer process might even open the door for the suggested atomic-scale interlocking-toy-brick-based stacking of different 2D materials, which will enable a more reliable fabrication of van der Waals heterostructure-based devices and applications.

  13. 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.

  14. Bi-directional power control system for voltage converter

    Science.gov (United States)

    Garrigan, Neil Richard; King, Robert Dean; Schwartz, James Edward

    1999-01-01

    A control system for a voltage converter includes: a power comparator for comparing a power signal on input terminals of the converter with a commanded power signal and producing a power comparison signal; a power regulator for transforming the power comparison signal to a commanded current signal; a current comparator for comparing the commanded current signal with a measured current signal on output terminals of the converter and producing a current comparison signal; a current regulator for transforming the current comparison signal to a pulse width modulator (PWM) duty cycle command signal; and a PWM for using the PWM duty cycle command signal to control electrical switches of the converter. The control system may further include: a command multiplier for converting a voltage signal across the output terminals of the converter to a gain signal having a value between zero (0) and unity (1), and a power multiplier for multiplying the commanded power signal by the gain signal to provide a limited commanded power signal, wherein power comparator compares the limited commanded power signal with the power signal on the input terminals.

  15. An improved direct torque controller applied to an electric vehicle

    Directory of Open Access Journals (Sweden)

    Miguel Durán

    2014-01-01

    Full Text Available Este artículo presenta la estructura básica, el modelo y el diseño de un controlador de par para un vehículo eléctrico (EV. El EV propuesto es el resultado de la conversión de un vehículo convencional a un vehículo eléctrico, donde el sistema de tracción original basado en un motor de combustión interna es remplazado por un sistema de tracción eléctrica. El controlador está basado en la técnica de control directo de par (DTC más un término que compensa la caída de voltaje en los devanados del estator del motor de inducción (IM. Con el fin de obtener una frecuencia de conmutación constante se utiliza la técnica de modulación PWM vectorial para generar los pulsos del inversor. Se presentan los resultados de simulación para probar el desempeño de la estrategia de control propuesta, la cual es comparada con el esquema de DTC convencional.

  16. A Review on Direct Power Control for Applications to Grid Connected PWM Converters

    Directory of Open Access Journals (Sweden)

    T. A. Trivedi

    2015-08-01

    Full Text Available The Direct Power Control strategy has become popular as an alternative to the conventional vector oriented control strategy for grid connected PWM converters. In this paper, Direct Power Control as applied to various applications of grid connected converters is reviewed. The Direct Power Control for PWM rectifiers, Grid Connected DC/AC inverters applications such as renewable energy sources interface, Active Power Filters, Doubly Fed Induction Generators and AC-DC-AC converters are discussed. Control strategies such as Look-Up table based control, predictive control, Virtual Flux DPC, Model based DPC and DPC-Space Vector Modulation are critically reviewed. The effects of various key parameters such as selection of switching vector, sampling time, hysteresis band and grid interfacing on performance of direct power controlled converters are presented.

  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. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Turbine Engine Clearance Control Systems: Current Practices and Future Directions

    Science.gov (United States)

    Lattime, Scott B.; Steinetz, Bruce M.

    2002-01-01

    Improved blade tip sealing in the high pressure compressor (HPC) and high pressure turbine (HPT) can provide dramatic reductions in specific fuel consumption (SFC), time-on-wing, compressor stall margin, and engine efficiency as well as increased payload and mission range capabilities. Maintenance costs to overhaul large commercial gas turbine engines can easily exceed $1M. Engine removal from service is primarily due to spent exhaust gas temperature (EGT) margin caused mainly by the deterioration of HPT components. Increased blade tip clearance is a major factor in hot section component degradation. As engine designs continue to push the performance envelope with fewer parts and the market drives manufacturers to increase service life, the need for advanced sealing continues to grow. A review of aero gas turbine engine HPT performance degradation and the mechanisms that promote these losses are discussed. Benefits to the HPT due to improved clearance management are identified. Past and present sealing technologies are presented along with specifications for next generation engine clearance control systems.

  19. 75 FR 80066 - Quality Control Requirements for Direct Endorsement Lenders; Notice of Proposed Information...

    Science.gov (United States)

    2010-12-21

    ... DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT [Docket No. FR-5380-N-50] Quality Control Requirements... information: Title of Proposal: Quality Control Requirements for Direct Endorsement Lenders. OMB Control... a result, DE lenders will be responsible for conducting quality control on TPO originations of FHA...

  20. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

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

  2. Direct product quality control for energy efficient climate controlled transport of agro-material

    NARCIS (Netherlands)

    Verdijck, G.J.C.; Preisig, H.A.; Straten, van G.

    2005-01-01

    A (model-based) Product Quality Controller is presented for climate controlled operations involving agro-material, such as storage and transport. This controller belongs to the class of Model Predictive Controllers and fits in a previously developed hierarchical control structure. The new Product

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

    Science.gov (United States)

    Hanna, M. F.

    1966-01-01

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

  4. Learning-based identification and iterative learning control of direct-drive robots

    NARCIS (Netherlands)

    Bukkems, B.H.M.; Kostic, D.; Jager, de A.G.; Steinbuch, M.

    2005-01-01

    A combination of model-based and Iterative Learning Control is proposed as a method to achieve high-quality motion control of direct-drive robots in repetitive motion tasks. We include both model-based and learning components in the total control law, as their individual properties influence the

  5. Direct design of LPV feedback controllers: technical details and numerical examples

    OpenAIRE

    Novara, Carlo

    2014-01-01

    The paper contains technical details of recent results developed by the author, regarding the design of LPV controllers directly from experimental data. Two numerical examples are also presented, about control of the Duffing oscillator and control of a two-degree-of-freedom manipulator.

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

    Directory of Open Access Journals (Sweden)

    Gasbaoui Brahim

    2011-01-01

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

  7. Integrated direct/indirect adaptive robust motion trajectory tracking control of pneumatic cylinders

    Science.gov (United States)

    Meng, Deyuan; Tao, Guoliang; Zhu, Xiaocong

    2013-09-01

    This paper studies the precision motion trajectory tracking control of a pneumatic cylinder driven by a proportional-directional control valve. An integrated direct/indirect adaptive robust controller is proposed. The controller employs a physical model based indirect-type parameter estimation to obtain reliable estimates of unknown model parameters, and utilises a robust control method with dynamic compensation type fast adaptation to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbances. Due to the use of projection mapping, the robust control law and the parameter adaption algorithm can be designed separately. Since the system model uncertainties are unmatched, the recursive backstepping technology is adopted to design the robust control law. Extensive comparative experimental results are presented to illustrate the effectiveness of the proposed controller and its performance robustness to parameter variations and sudden disturbances.

  8. Gynecologic Cancer Prevention and Control in the National Comprehensive Cancer Control Program: Progress, Current Activities, and Future Directions

    OpenAIRE

    Stewart, Sherri L.; Lakhani, Naheed; Brown, Phaeydra M.; Larkin, O. Ann; Moore, Angela R.; Hayes, Nikki S.

    2013-01-01

    Gynecologic cancer confers a large burden among women in the United States. Several evidence-based interventions are available to reduce the incidence, morbidity, and mortality from these cancers. The National Comprehensive Cancer Control Program (NCCCP) is uniquely positioned to implement these interventions in the US population. This review discusses progress and future directions for the NCCCP in preventing and controlling gynecologic cancer.

  9. Gynecologic cancer prevention and control in the National Comprehensive Cancer Control Program: progress, current activities, and future directions.

    Science.gov (United States)

    Stewart, Sherri L; Lakhani, Naheed; Brown, Phaeydra M; Larkin, O Ann; Moore, Angela R; Hayes, Nikki S

    2013-08-01

    Gynecologic cancer confers a large burden among women in the United States. Several evidence-based interventions are available to reduce the incidence, morbidity, and mortality from these cancers. The National Comprehensive Cancer Control Program (NCCCP) is uniquely positioned to implement these interventions in the US population. This review discusses progress and future directions for the NCCCP in preventing and controlling gynecologic cancer.

  10. 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 case there is imbalance between demand and supply. We consider heterogeneous consumers at the bottom level, namely a cold storage in supermarkets and a chiller equipped with ice storage. These consumers are under the direct control of a mid-level controller, a so-called aggregator. The aggregator...... by the aggregator....

  11. Effects of the integrated pollution prevention and control directive on environmental protection

    Energy Technology Data Exchange (ETDEWEB)

    Kat, W. [Corus Staal BV, Evironmental Manangement Dept. (Netherlands)

    2005-06-01

    The Integrated Pollution Prevention and Control Directive (IPPC) published in the EU in 1996 is presented within an approach based on source-targeted measures. The Directive implementation is based on the granting of permits and it introduces new concepts like Best Available Technique (BAT), Best Reference Document (BREF) and Level Playing Field (LPF). The consequences for the EU steel industry are discussed. (author)

  12. The Stability Analysis and New Torque Control Strategy of Direct-Driven PMSG Wind Turbines

    OpenAIRE

    Jun Liu; Feihang Zhou; Gungyi Wang

    2016-01-01

    This paper expounds on the direct-driven PMSG wind power system control strategy, and analyses the stability conditions of the system. The direct-driven PMSG wind power system may generate the intense mechanical vibration, when wind speed changes dramatically. This paper proposes a new type of torque control strategy, which increases the system damping effectively, mitigates mechanical vibration of the system, and enhances the stability conditions of the system. The simulation results verify ...

  13. 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.

  14. Reliance on habits at the expense of goal-directed control following dopamine precursor depletion

    OpenAIRE

    de Wit, Sanne; Standing, Holly R.; DeVito, Elise E.; Robinson, Oliver J.; Ridderinkhof, K. Richard; Robbins, Trevor W.; Sahakian, Barbara J.

    2011-01-01

    Rationale Dopamine is well known to play an important role in learning and motivation. Recent animal studies have implicated dopamine in the reinforcement of stimulus?response habits, as well as in flexible, goal-directed action. However, the role of dopamine in human action control is still not well understood. Objectives We present the first investigation of the effect of reducing dopamine function in healthy volunteers on the balance between habitual and goal-directed action control. Metho...

  15. 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

    1999-12-31

    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

  16. 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

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

    International Nuclear Information System (INIS)

    Karpeta, C.

    1979-01-01

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

  18. 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...... 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...

  19. 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.

  20. 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

    2017-02-01

    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.

  1. 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.

  2. 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...

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

    KAUST Repository

    Huang, Bin-Juine; Chen, Chun-Wei; Hsu, Po-Chien; Tseng, Wei-Min; Wu, Min-Sheng

    2012-01-01

    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

  4. The Evolution of Cost/Schedule Control (Direct Labor) in Naval Shipyards

    National Research Council Canada - National Science Library

    Gessis, Scott N

    1992-01-01

    The evolution of a Cost/Schedule Control System (C/SCS), for direct labor, in naval shipyards can be traced from the cost/schedule control concept used in the Air Force in the 1960s, as an initiative toward more reliable data...

  5. Direct Adaptive Control of a Class of Nonlinear Discrete-Time Systems

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon

    2004-01-01

    In this paper we deal with direct adaptive control of a specific class of discrete-time SISO systems, where the nonlinearities are convex and an upper bound is known. We use a control law based on a linear combination of a set of globally uniformly bounded basis functions with compact support, wh...

  6. Model and control scheme for recirculation mode direct steam generation parabolic trough solar power plants

    International Nuclear Information System (INIS)

    Guo, Su; Liu, Deyou; Chen, Xingying; Chu, Yinghao; Xu, Chang; Liu, Qunming; Zhou, Ling

    2017-01-01

    Highlights: •A nonlinear dynamic model of recirculation DSG parabolic trough is developed. •Collector row, water separator and spray attemperator are modeled, respectively. •The dynamic behaviors of the collector field are simulated and analyzed. •Transfer functions of water level and outlet fluid temperature are derived. •Multi-model switching generalized predictive control strategy is developed. -- Abstract: This work describes and evaluates a new nonlinear dynamic model, and a new generalized predictive control scheme for a collector field of direct steam generation parabolic troughs in recirculation mode. Modeling the dynamic behaviors of collector fields is essential to design, testing and validation of automatic control systems for direct steam generation parabolic troughs. However, the behaviors of two-phase heat transfer fluids impose challenges to simulating and developing process control schemes. In this work, a new nonlinear dynamic model is proposed, based on the nonlinear distributed parameter and the nonlinear lumped parameter methods. The proposed model is used to simulate and analyze the dynamic behaviors of the entire collector field for recirculation mode direct steam generation parabolic troughs under different weather conditions, without excessive computational costs. Based on the proposed model, transfer functions for both the water level of the separator and outlet steam temperatures are derived, and a new multi-model switching generalized predictive control scheme is developed for simulated control of the plant behaviors for a wide region of operational conditions. The proposed control scheme achieves excellent control performance and robustness for systems with long delay, large inertia and time-varying parameters, and efficiently solves the model mismatching problem in direct steam generation parabolic troughs. The performances of the model and control scheme are validated with design data from the project of Integration of Direct

  7. Direct experience while eating: Laboratory outcomes among individuals with eating disorders versus healthy controls.

    Science.gov (United States)

    Elices, Matilde; Carmona, Cristina; Narváez, Vanessa; Seto, Victoria; Martin-Blanco, Ana; Pascual, Juan C; Soriano, José; Soler, Joaquim

    2017-12-01

    To compare individuals with eating disorders (EDs) to healthy controls (HCs) to assess for differences in direct engagement in the eating process. Participants (n=58) were asked to eat an orange slice. To assess the degree of direct engagement with the eating process, participants were asked to write down 10 thoughts about the experience of eating the orange slice. Next, the participants were instructed to classify the main focus of each thought as either experiential ("direct experience") or analytical ("thinking about"). A direct experience index (DEI) was computed by dividing the number of times that participants classified an experience as a "direct experience" (the numerator) by the total number of all observations (i.e., direct experience+thinking about). Participants also completed the Five Facet Mindfulness Questionnaire (FFMQ) and the Experiences Questionnaire (EQ) to assess mindfulness facets and decentering, respectively. Compared to controls, participants in the EDs group presented significantly lower levels of direct experience during the eating task (EDs group: mean=43.54, SD=29.64; HCs group: mean=66.17, SD=22.23, p=0.03). Participants in the EDs group also scored significantly lower on other mindfulness-related variables. These findings suggest that engagement with the direct experience of eating is lower in individuals with EDs. Future research should investigate the role of mindfulness-based interventions to address direct experience while eating in individuals with EDs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. 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=managers' responsibility. Copyright © 2013 Longwoods Publishing.

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

    Directory of Open Access Journals (Sweden)

    Hamayun Mirza Tariq

    2015-03-01

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

  10. 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

    . 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......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...

  11. A New Real Time Lyapunov Based Controller for Power Quality Improvement in Unified Power Flow Controllers Using Direct Matrix Converters

    Directory of Open Access Journals (Sweden)

    Joaquim Monteiro

    2017-06-01

    Full Text Available This paper proposes a Direct Matrix Converter operating as a Unified Power Flow Controller (DMC-UPFC with an advanced control method for UPFC, based on the Lyapunov direct method, presenting good results in power quality assessment. This control method is used for real-time calculation of the appropriate matrix switching state, determining which switching state should be applied in the following sampling period. The control strategy takes into account active and reactive power flow references to choose the vector converter closest to the optimum. Theoretical principles for this new real-time vector modulation and control applied to the DMC-UPFC with input filter are established. The method needs DMC-UPFC dynamic equations to be solved just once in each control cycle, to find the required optimum vector, in contrast to similar control methods that need 27 vector estimations per control cycle. The designed controller’s performance was evaluated using Matlab/Simulink software. Controllers were also implemented using a digital signal processing (DSP system and matrix hardware. Simulation and experimental results show decoupled transmission line active (P and reactive (Q power control with zero theoretical error tracking and fast response. Output currents and voltages show small ripple and low harmonic content.

  12. Exponential cluster synchronization in directed community networks via adaptive nonperiodically intermittent pinning control

    Science.gov (United States)

    Zhou, Peipei; Cai, Shuiming; Jiang, Shengqin; Liu, Zengrong

    2018-02-01

    In this paper, the problem of exponential cluster synchronization for a class of directed community networks is investigated via adaptive nonperiodically intermittent pinning control. By constructing a novel piecewise continuous Lyapunov function, some sufficient conditions to guarantee globally exponential cluster synchronization are derived. It is noted that the derived cluster synchronization criteria rely on the control rates, but not the control widths or the control periods, which facilitates the choice of the control periods in practical applications. A numerical example is finally presented to show the effectiveness of the obtained theoretical results.

  13. 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...... Direct Current Control (MPDCC) leads to an increase of torque control performance taking into account the discrete nature of inverters but temporary offsets and poor responses to load torque variations are still issues in speed control. A load torque estimator is proposed in this paper in order...

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

    International Nuclear Information System (INIS)

    Sarasola, Izaskun; Poza, Javier; Rodriguez, Miguel A.; Abad, Gonzalo

    2011-01-01

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

  15. Control of impulsive renewal systems: Application to direct design in networked control

    NARCIS (Netherlands)

    Guerreiro Tome Antunes, D.J.; Hespanha, J.P.; Silvestre, C.J.

    2009-01-01

    We consider the control of impulsive systems with independent and identically distributed intervals between jumps. The control action and output measurement are assumed to take place only at jump times. We give necessary and sufficient conditions, in the form of LMIs, for mean square stabilizability

  16. Installation of PMV Operation Program in DDC Controller and Air Conditioning Control Using PMV Directly as Set Point

    Science.gov (United States)

    Haramoto, Ken-Ichi

    In general, air conditioning control in a building is operated mainly by indoor air temperature control. Although the operators of the machine in the building accepted a claim for indoor air temperature presented by the building inhabitants, the indoor conditions have been often too cool or warm. Therefore, in an attempt to create better thermal environments, the author paid attention to the PMV that is a thermal comfort index. And then, the possibility of air conditioning control using the PMV directly as the set point was verified by employing actual equipment in an air conditioning testing room and an office building. Prior to the execution of this control, the operation program of the PMV was installed in a DDC controller for the air conditioning control. And information from indoor sensors and so on was inputted to the controller, and the computed PMV was used as the feedback variable.

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

    DEFF Research Database (Denmark)

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

    2002-01-01

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

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

    International Nuclear Information System (INIS)

    Lisowski, E.; Czyżycki, W.; Rajda, J.

    2014-01-01

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

  19. A fuzzy logic sliding mode controlled electronic differential for a direct wheel drive EV

    Science.gov (United States)

    Ozkop, Emre; Altas, Ismail H.; Okumus, H. Ibrahim; Sharaf, Adel M.

    2015-11-01

    In this study, a direct wheel drive electric vehicle based on an electronic differential system with a fuzzy logic sliding mode controller (FLSMC) is studied. The conventional sliding surface is modified using a fuzzy rule base to obtain fuzzy dynamic sliding surfaces by changing its slopes using the global error and its derivative in a fuzzy logic inference system. The controller is compared with proportional-integral-derivative (PID) and sliding mode controllers (SMCs), which are usually preferred to be used in industry. The proposed controller provides robustness and flexibility to direct wheel drive electric vehicles. The fuzzy logic sliding mode controller, electronic differential system and the overall electrical vehicle mechanism are modelled and digitally simulated by using the Matlab software. Simulation results show that the system with FLSMC has better efficiency and performance compared to those of PID and SMCs.

  20. FUZZY LOGIC BASED ADAPTATION MECHANISM FOR ADAPTIVE LUENBERGER OBSERVER SENSORLESS DIRECT TORQUE CONTROL OF INDUCTION MOTOR

    Directory of Open Access Journals (Sweden)

    A. BENNASSAR

    2016-01-01

    Full Text Available Many industrial applications require high performance speed sensorless operation and demand new control methods in order to obtain fast dynamic response and insensitive to external disturbances. The current research aims to present the performance of the sensorless direct torque control (DTC of an induction motor (IM using adaptive Luenberger observer (ALO with fuzzy logic controller (FLC for adaptation mechanism. The rotor speed is regulated by proportional integral (PI anti-windup controller. The proposed strategy is directed to reduce the ripple on the torque and the flux. Numerical simulation results show the good performance and effectiveness of the proposed sensorless control for different references of the speed even both low and high speeds.

  1. High-Alpha Research Vehicle Lateral-Directional Control Law Description, Analyses, and Simulation Results

    Science.gov (United States)

    Davidson, John B.; Murphy, Patrick C.; Lallman, Frederick J.; Hoffler, Keith D.; Bacon, Barton J.

    1998-01-01

    This report contains a description of a lateral-directional control law designed for the NASA High-Alpha Research Vehicle (HARV). The HARV is a F/A-18 aircraft modified to include a research flight computer, spin chute, and thrust-vectoring in the pitch and yaw axes. Two separate design tools, CRAFT and Pseudo Controls, were integrated to synthesize the lateral-directional control law. This report contains a description of the lateral-directional control law, analyses, and nonlinear simulation (batch and piloted) results. Linear analysis results include closed-loop eigenvalues, stability margins, robustness to changes in various plant parameters, and servo-elastic frequency responses. Step time responses from nonlinear batch simulation are presented and compared to design guidelines. Piloted simulation task scenarios, task guidelines, and pilot subjective ratings for the various maneuvers are discussed. Linear analysis shows that the control law meets the stability margin guidelines and is robust to stability and control parameter changes. Nonlinear batch simulation analysis shows the control law exhibits good performance and meets most of the design guidelines over the entire range of angle-of-attack. This control law (designated NASA-1A) was flight tested during the Summer of 1994 at NASA Dryden Flight Research Center.

  2. Nurse- vs nomogram-directed glucose control in a cardiovascular intensive care unit.

    Science.gov (United States)

    Chant, Clarence; Mustard, Mary; Thorpe, Kevin E; Friedrich, Jan O

    2012-07-01

    Paper-based nomograms are reasonably effective for achieving glycemic control but have low adherence and are less adaptive than nurses' judgment. To compare efficacy (glucose control) and safety (hypoglycemia) achieved by use of a paper nomogram versus nurses' judgment. Prospective, randomized, open-label, crossover trial in an intensive care unit in postoperative patients with glucose concentrations greater than 8 mmol/L. Consenting nurses with at least 1 year of experience were randomized to use either their judgment or a validated paper-based nomogram for glucose control. After completion of 2 study shifts, the nurses used the alternative method for the next 2 study shifts. Glucose target level and safety and efficacy boundaries were the same for both methods. The primary end point was area under glucose time curve per hour. Thirty-four nurses contributed 95 shifts of data (44 nomogram-directed, 51 nurse-directed). Adherence to the nomogram was higher in the nomogram group than hypothetical adherence in the nurse-directed group for correct adjustments in insulin infusion (70% vs 37%; P unit where nurses generally accepted the need for tight glucose control, nurse-directed control was as effective and as safe as nomogram-based control.

  3. A Direct Adaptive Control Approach in the Presence of Model Mismatch

    Science.gov (United States)

    Joshi, Suresh M.; Tao, Gang; Khong, Thuan

    2009-01-01

    This paper considers the problem of direct model reference adaptive control when the plant-model matching conditions are violated due to abnormal changes in the plant or incorrect knowledge of the plant's mathematical structure. The approach consists of direct adaptation of state feedback gains for state tracking, and simultaneous estimation of the plant-model mismatch. Because of the mismatch, the plant can no longer track the state of the original reference model, but may be able to track a new reference model that still provides satisfactory performance. The reference model is updated if the estimated plant-model mismatch exceeds a bound that is determined via robust stability and/or performance criteria. The resulting controller is a hybrid direct-indirect adaptive controller that offers asymptotic state tracking in the presence of plant-model mismatch as well as parameter deviations.

  4. Control loop design and control performance study on direct internal reforming solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.; Weng, S.; Su, M. [Key Laboratory of Power Machinery and Engineering of the Education Ministry, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2009-10-15

    A solid oxide fuel cell (SOFC) stack is a complicated nonlinear power system. Its system model includes a set of partial differential equations that describe species, mass, momentum and energy conservation, as well as the electrochemical reaction models. The validation and verification of the control system by experiment is very expensive and difficult. Based on the distributed and lumped model of a one-dimensional SOFC, the dynamic performance with different control loops for SOFC is investigated. The simulation result proves that the control system is appropriate and feasible, and can effectively satisfy the requirement of variable load power demand. This simulation model not only can prevent some latent dangers of the fuel cell system but also predict the distributed parameters' characteristics inside the SOFC system. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

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

    Science.gov (United States)

    1984-05-01

    Control Ignored any error of 1/10th degree or less. This was done by setting the error term E and the integral sum PREINT to zero If then absolute value of...signs of two errors jeq tdiff if equal, jump clr @preint else zero integal sum tdiff mov @diff,rl fetch absolute value of OAT-RAT ci rl,25 is...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

  6. 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. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  7. A osteogenesis distraction device enabling control of vertical direction for syndromic craniosynostosis.

    Science.gov (United States)

    Kobayashi, Shinji; Fukawa, Toshihiko; Hirakawa, Takashi; Maegawa, Jiro

    2014-02-01

    We have developed a hybrid facial osteogenesis distraction system that combines the advantages of external and internal distraction devices to enable control of both the distraction distance and vector. However, when the advanced maxilla has excessive clockwise rotation and shifts more downward vertically than planned, it might be impossible to pull it up to correct it. We invented devices attached to external distraction systems that can control the vertical vector of distraction to resolve this problem. The purpose of this article is to describe the result of utilizing the distraction system for syndromic craniosynostosis. In addition to a previously reported hybrid facial distraction system, the devices for controlling the vertical direction of the advanced maxilla were attached to the external distraction device. The vertical direction of the advanced maxilla can be controlled by adjustment of the spindle units. This system was used for 2 patients with Crouzon and Apert syndrome. The system enabled control of the vertical distance, with no complications during the procedures. As a result, the maxilla could be advanced into the planned position including overcorrection without excessive clockwise rotation of distraction. Our system can alter the cases and bring them into the planned position, by controlling the vertical vector of distraction. We believe that this system might be effective in infants with syndromic craniosynostosis as it involves 2 osteotomies and horizontal and vertical direction of elongation can be controlled.

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

    International Nuclear Information System (INIS)

    Sellner, D.; Schnutenhaus, J.

    1993-01-01

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

  10. 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......, programmable from the microcomputer, to control the sample volume. No pre-treatment of the samples is necessary. The limit of detection is 0.14 mg l–1, and only small amounts of serum (

  11. Direct torque control method applied to the WECS based on the PMSG and controlled with backstepping approach

    Science.gov (United States)

    Errami, Youssef; Obbadi, Abdellatif; Sahnoun, Smail; Ouassaid, Mohammed; Maaroufi, Mohamed

    2018-05-01

    This paper proposes a Direct Torque Control (DTC) method for Wind Power System (WPS) based Permanent Magnet Synchronous Generator (PMSG) and Backstepping approach. In this work, generator side and grid-side converter with filter are used as the interface between the wind turbine and grid. Backstepping approach demonstrates great performance in complicated nonlinear systems control such as WPS. So, the control method combines the DTC to achieve Maximum Power Point Tracking (MPPT) and Backstepping approach to sustain the DC-bus voltage and to regulate the grid-side power factor. In addition, control strategy is developed in the sense of Lyapunov stability theorem for the WPS. Simulation results using MATLAB/Simulink validate the effectiveness of the proposed controllers.

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

    International Nuclear Information System (INIS)

    Chida, Koichi; Zuguchi, Masayuki; Ito, Daisuke; Sato, Kunihiko; Shimura, Hirotaka; Sasaki, Masatoshi

    2001-01-01

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

  13. Reliance on habits at the expense of goal-directed control following dopamine precursor depletion.

    Science.gov (United States)

    de Wit, Sanne; Standing, Holly R; Devito, Elise E; Robinson, Oliver J; Ridderinkhof, K Richard; Robbins, Trevor W; Sahakian, Barbara J

    2012-01-01

    Dopamine is well known to play an important role in learning and motivation. Recent animal studies have implicated dopamine in the reinforcement of stimulus-response habits, as well as in flexible, goal-directed action. However, the role of dopamine in human action control is still not well understood. We present the first investigation of the effect of reducing dopamine function in healthy volunteers on the balance between habitual and goal-directed action control. The dietary intervention of acute dietary phenylalanine and tyrosine depletion (APTD) was adopted to study the effects of reduced global dopamine function on action control. Participants were randomly assigned to either the APTD or placebo group (ns = 14) to allow for a between-subjects comparison of performance on a novel three-stage experimental paradigm. In the initial learning phase, participants learned to respond to different stimuli in order to gain rewarding outcomes. Subsequently, an outcome-devaluation test and a slips-of-action test were conducted to assess whether participants were able to flexibly adjust their behaviour to changes in the desirability of the outcomes. APTD did not prevent stimulus-response learning, nor did we find evidence for impaired response-outcome learning in the subsequent outcome-devaluation test. However, when goal-directed and habitual systems competed for control in the slips-of-action test, APTD tipped the balance towards habitual control. These findings were restricted to female volunteers. We provide direct evidence that the balance between goal-directed and habitual control in humans is dopamine dependent. The results are discussed in light of gender differences in dopamine function and psychopathologies.

  14. 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.

  15. 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. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Parameter Improved Particle Swarm Optimization Based Direct-Current Vector Control Strategy for Solar PV System

    Directory of Open Access Journals (Sweden)

    NAMMALVAR, P.

    2018-02-01

    Full Text Available This paper projects Parameter Improved Particle Swarm Optimization (PIPSO based direct current vector control technology for the integration of photovoltaic array in an AC micro-grid to enhance the system performance and stability. A photovoltaic system incorporated with AC micro-grid is taken as the pursuit of research study. The test system features two power converters namely, PV side converter which consists of DC-DC boost converter with Perturbation and Observe (P&O MPPT control to reap most extreme power from the PV array, and grid side converter which consists of Grid Side-Voltage Source Converter (GS-VSC with proposed direct current vector control strategy. The gain of the proposed controller is chosen from a set of three values obtained using apriori test and tuned through the PIPSO algorithm so that the Integral of Time multiplied Absolute Error (ITAE between the actual and the desired DC link capacitor voltage reaches a minimum and allows the system to extract maximum power from PV system, whereas the existing d-q control strategy is found to perform slowly to control the DC link voltage under varying solar insolation and load fluctuations. From simulation results, it is evident that the proposed optimal control technique provides robust control and improved efficiency.

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

    DEFF Research Database (Denmark)

    Persson, Frederik; Lewis, Julia B; Lewis, Edmund J

    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 ...

  18. Corticostriatal connectivity underlies individual differences in the balance between habitual and goal-directed action control

    NARCIS (Netherlands)

    Wit, S. de; Watson, A.J.P.; Harsay, H.A.; Cohen, M.X.; Vijver, I. van de; Ridderinkhof, K.R.

    2012-01-01

    Why are some individuals more susceptible to the formation of inflexible habits than others? In the present study, we used diffusion tensor imaging to demonstrate that brain connectivity predicts individual differences in relative goal-directed and habitual behavioral control in humans.

  19. On the electric signal direction indicator for teh control of road traffic ...

    African Journals Online (AJOL)

    An electronic signal direction indicator (ESDI) for the control of road traffic has been designed, constructed and studied. The construction was done using 555 timer IC, a transistor-transistor logic compatible device that can operate in several modes as the major active element. The ESDI system circuit is reliable, satisfactorily ...

  20. 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…

  1. 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...

  2. Self-directed learning skills in air-traffic control; A cued retrospective reporting study

    NARCIS (Netherlands)

    Van Meeuwen, Ludo; Brand-Gruwel, Saskia; Van Merriënboer, Jeroen; Kirschner, Paul A.; De Bock, Jeano

    2011-01-01

    Van Meeuwen, L. W., Brand-Gruwel, S., Van Merriënboer, J. J. G., Kirschner, P. A., & De Bock, J. J. P. R. (2010, May). Self-directed learning skills in air-traffic control; A cued retrospective reporting study. Presented at the Scandinavian Workshop on Applied Eye-tracking. Lund, Sweden.

  3. Reliance on habits at the expense of goal-directed control following dopamine precursor depletion

    NARCIS (Netherlands)

    de Wit, S.; Standing, H.R.; DeVito, E.E.; Robinson, O.J.; Ridderinkhof, K.R.; Robbins, T.W.; Sahakian, B.J.

    2012-01-01

    Rationale Dopamine is well known to play an important role in learning and motivation. Recent animal studies have implicated dopamine in the reinforcement of stimulus-response habits, as well as in flexible, goal-directed action. However, the role of dopamine in human action control is still not

  4. Self-directed learning skills in air-traffic control training; An eye-tracking approach

    NARCIS (Netherlands)

    Van Meeuwen, Ludo; Brand-Gruwel, Saskia; Van Merriënboer, Jeroen; Bock, Jeano; Kirschner, Paul A.

    2011-01-01

    Van Meeuwen, L. W., Brand-Gruwel, S., De Bock, J. J. P. R., Kirschner, P. A., & Van Merriënboer, J. J. G. (2010, September). Self-directed Learning Skills in Air-traffic Control Training; An Eye-tracking Approach. Paper presented at the European Association for Aviation Psychology, Budapest.

  5. Voltage directive drive with claw pole motor and control without rotor position indicator

    Science.gov (United States)

    Stroenisch, Volker Ewald

    Design and testing of a voltage directive drive for synchronous variable speed claw pole motor and control without rotor position indicator is described. Economic analysis of the designed regulation is performed. Computations of stationary and dynamic behavior are given and experimental operational behavior is determined. The motors can be used for electric transportation vehicles, diesel motors, and electric railway engines.

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

    Science.gov (United States)

    Molchanov, Pavlo A.; Contarino, Vincent M.

    2013-06-01

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

  7. A multiple-fan active control wind tunnel for outdoor wind speed and direction simulation

    Science.gov (United States)

    Wang, Jia-Ying; Meng, Qing-Hao; Luo, Bing; Zeng, Ming

    2018-03-01

    This article presents a new type of active controlled multiple-fan wind tunnel. The wind tunnel consists of swivel plates and arrays of direct current fans, and the rotation speed of each fan and the shaft angle of each swivel plate can be controlled independently for simulating different kinds of outdoor wind fields. To measure the similarity between the simulated wind field and the outdoor wind field, wind speed and direction time series of two kinds of wind fields are recorded by nine two-dimensional ultrasonic anemometers, and then statistical properties of the wind signals in different time scales are analyzed based on the empirical mode decomposition. In addition, the complexity of wind speed and direction time series is also investigated using multiscale entropy and multivariate multiscale entropy. Results suggest that the simulated wind field in the multiple-fan wind tunnel has a high degree of similarity with the outdoor wind field.

  8. Tryptophan Depletion Promotes Habitual over Goal-Directed Control of Appetitive Responding in Humans.

    Science.gov (United States)

    Worbe, Yulia; Savulich, George; de Wit, Sanne; Fernandez-Egea, Emilio; Robbins, Trevor W

    2015-02-05

    Optimal behavioral performance results from a balance between goal-directed and habitual systems of behavioral control, which are modulated by ascending monoaminergic projections. While the role of the dopaminergic system in behavioral control has been recently addressed, the extent to which changes in global serotonin neurotransmission could influence these 2 systems is still poorly understood. We employed the dietary acute tryptophan depletion procedure to reduce serotonin neurotransmission in 18 healthy volunteers and 18 matched controls. We used a 3-stage instrumental learning paradigm that includes an initial instrumental learning stage, a subsequent outcome-devaluation test, and a slip-of-action stage, which directly tests the balance between hypothetical goal-directed and habitual systems. We also employed a separate response inhibition control test to assess the behavioral specificity of the results. Acute tryptophan depletion produced a shift of behavioral performance towards habitual responding as indexed by performance on the slip-of-action test. Moreover, greater habitual responding in the acute tryptophan depletion group was predicted by a steeper decline in plasma tryptophan levels. In contrast, acute tryptophan depletion left intact the ability to use discriminative stimuli to guide instrumental choice as indexed by the instrumental learning stage and did not impair inhibitory response control. The major implication of this study is that serotonin modulates the balance between goal-directed and stimulus-response habitual systems of behavioral control. Our findings thus imply that diminished serotonin neurotransmission shifts behavioral control towards habitual responding. © The Author 2015. Published by Oxford University Press on behalf of CINP.

  9. Resolution of conflict between goal-directed actions: outcome encoding and neural control processes.

    Science.gov (United States)

    de Wit, Sanne; Ostlund, Sean B; Balleine, Bernard W; Dickinson, Anthony

    2009-07-01

    According to O-R theory of instrumental learning, incongruent biconditional discriminations should be impossible to solve in a goal-directed manner because the event acting as the outcome of one response also acts as a discriminative stimulus for an opposite response. Each event should therefore be associated with two competing responses. However, Dickinson and de Wit (2003) have presented evidence that rats can learn incongruent discriminations. The present study investigated whether rats were able to engage additional processes to solve incongruent discriminations in a goal-directed manner. Experiment 1 provides evidence that rats resolve the response conflict that arises in the incongruent discrimination by differentially encoding events in their roles as discriminative stimulus and as outcome. Furthermore, Experiment 2 shows that once goal-directed control has been established the dorsomedial prefrontal cortex is not directly involved in its maintenance but rather plays a central role in conflict resolution processes.

  10. Direct Evidence for Vision-based Control of Flight Speed in Budgerigars.

    Science.gov (United States)

    Schiffner, Ingo; Srinivasan, Mandyam V

    2015-06-05

    We have investigated whether, and, if so, how birds use vision to regulate the speed of their flight. Budgerigars, Melopsittacus undulatus, were filmed in 3-D using high-speed video cameras as they flew along a 25 m tunnel in which stationary or moving vertically oriented black and white stripes were projected on the side walls. We found that the birds increased their flight speed when the stripes were moved in the birds' flight direction, but decreased it only marginally when the stripes were moved in the opposite direction. The results provide the first direct evidence that Budgerigars use cues based on optic flow, to regulate their flight speed. However, unlike the situation in flying insects, it appears that the control of flight speed in Budgerigars is direction-specific. It does not rely solely on cues derived from optic flow, but may also be determined by energy constraints.

  11. Sensorless direct voltage control of the stand-alone brushless doubly-fed generator

    DEFF Research Database (Denmark)

    Liu, Yi; Xu, Wei; Xiong, Fei

    2017-01-01

    The conventional stand-alone brushless doubly-fed generator (BDFG) control strategies need the feedback from the rotor position or speed sensors, which can reduce system reliability and increase the cost and axial volume of the machine. In this paper, a sensorless direct voltage control (DVC) str......) strategy is presented for the stand-alone BDFG. The satisfactory dynamic performance is verified by experimental results under four kinds of typical operation conditions. Besides, the proposed control strategy is robust due to no generator parameters being required....

  12. Phase-controlled localization and directed transport in an optical bipartite lattice.

    Science.gov (United States)

    Hai, Kuo; Luo, Yunrong; Lu, Gengbiao; Hai, Wenhua

    2014-02-24

    We investigate coherent control of a single atom interacting with an optical bipartite lattice via a combined high-frequency modulation. Our analytical results show that the quantum tunneling and dynamical localization can depend on phase difference between the modulation components, which leads to a different route for the coherent destruction of tunneling and a convenient phase-control method for stabilizing the system to implement the directed transport of atom. The similar directed transport and the phase-controlled quantum transition are revealed for the corresponding many-particle system. The results can be referable for experimentally manipulating quantum transport and transition of cold atoms in the tilted and shaken optical bipartite lattice or of analogical optical two-mode quantum beam splitter, and also can be extended to other optical and solid-state systems.

  13. 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. PMID:25152913

  14. 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.

  15. A real-time comparison between direct control, sequential pattern recognition control and simultaneous pattern recognition control using a Fitts' law style assessment procedure.

    Science.gov (United States)

    Wurth, Sophie M; Hargrove, Levi J

    2014-05-30

    Pattern recognition (PR) based strategies for the control of myoelectric upper limb prostheses are generally evaluated through offline classification accuracy, which is an admittedly useful metric, but insufficient to discuss functional performance in real time. Existing functional tests are extensive to set up and most fail to provide a challenging, objective framework to assess the strategy performance in real time. Nine able-bodied and two amputee subjects gave informed consent and participated in the local Institutional Review Board approved study. We designed a two-dimensional target acquisition task, based on the principles of Fitts' law for human motor control. Subjects were prompted to steer a cursor from the screen center of into a series of subsequently appearing targets of different difficulties. Three cursor control systems were tested, corresponding to three electromyography-based prosthetic control strategies: 1) amplitude-based direct control (the clinical standard of care), 2) sequential PR control, and 3) simultaneous PR control, allowing for a concurrent activation of two degrees of freedom (DOF). We computed throughput (bits/second), path efficiency (%), reaction time (second), and overshoot (%)) and used general linear models to assess significant differences between the strategies for each metric. We validated the proposed methodology by achieving very high coefficients of determination for Fitts' law. Both PR strategies significantly outperformed direct control in two-DOF targets and were more intuitive to operate. In one-DOF targets, the simultaneous approach was the least precise. The direct control was efficient in one-DOF targets but cumbersome to operate in two-DOF targets through a switch-depended sequential cursor control. We designed a test, capable of comprehensively describing prosthetic control strategies in real time. When implemented on control subjects, the test was able to capture statistically significant differences (p

  16. Direct-current vector control of three-phase grid-connected rectifier-inverter

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuhui; Haskew, Timothy A.; Hong, Yang-Ki; Xu, Ling [Department of Electrical and Computer Engineering, University of Alabama, Tuscaloosa, AL 35475 (United States)

    2011-02-15

    The three-phase grid-connected converter is widely used in renewable and electric power system applications. Traditionally, control of the three-phase grid-connected converter is based on the standard decoupled d-q vector control mechanism. Nevertheless, the study of this paper shows that there is a limitation in the conventional standard vector control method. Some of the limitations have also been found recently by other researchers. To overcome the shortage of the conventional vector control technique, this paper proposes a new direct-current d-q vector control mechanism in a nested-loop control structure, based on which an optimal control strategy is developed in a nonlinear programming formulation. The behaviors of both the conventional and proposed control methods are compared and evaluated in simulation and laboratory hardware experiment environments, both of which demonstrates that the proposed approach is effective for grid-connected power converter control in a wide system conditions while the conventional standard vector control approach may behave improperly especially when the converter operates beyond its PWM saturation limit. (author)

  17. 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.

  18. 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.

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

    International Nuclear Information System (INIS)

    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 ℝ 3 . 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 ℝ 3 . 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. (paper)

  20. 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.

  1. 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.

  2. Direct numerical simulation of turbulent channel flow with spanwise alternatively distributed strips control

    Science.gov (United States)

    Ni, Weidan; Lu, Lipeng; Fang, Jian; Moulinec, Charles; Yao, Yufeng

    2018-05-01

    The effect of spanwise alternatively distributed strips (SADS) control on turbulent flow in a plane channel has been studied by direct numerical simulations to investigate the characteristics of large-scale streamwise vortices (LSSVs) induced by small-scale active wall actuation, and their potential in suppressing flow separation. SADS control is realized by alternatively arranging out-of-phase control (OPC) and in-phase control (IPC) wall actuations on the lower channel wall surface, in the spanwise direction. It is found that the coherent structures are suppressed or enhanced alternatively by OPC or IPC, respectively, leading to the formation of a vertical shear layer, which is responsible for the LSSVs’ presence. Large-scale low-speed region can also be observed above the OPC strips, which resemble large-scale low-speed streaks. LSSVs are found to be in a statistically-converged steady state and their cores are located between two neighboring OPC and IPC strips. Their motions contribute significantly to the momentum transport in the wall-normal and spanwise directions, demonstrating their potential ability to suppress flow separation.

  3. Transcranial direct current stimulation for depression in Alzheimer's disease: study protocol for a randomized controlled trial.

    Science.gov (United States)

    Narita, Zui; Yokoi, Yuma

    2017-06-19

    Patients with Alzheimer's disease frequently elicit neuropsychiatric symptoms as well as cognitive deficits. Above all, depression is one of the most common neuropsychiatric symptoms in Alzheimer's disease but antidepressant drugs have not shown significant beneficial effects on it. Moreover, electroconvulsive therapy has not ensured its safety for potential severe adverse events although it does show beneficial clinical effect. Transcranial direct current stimulation can be the safe alternative of neuromodulation, which applies weak direct electrical current to the brain. Although transcranial direct current stimulation has plausible evidence for its effect on depression in young adult patients, no study has explored it in older subjects with depression in Alzheimer's disease. Therefore, we present a study protocol designed to evaluate the safety and clinical effect of transcranial direct current stimulation on depression in Alzheimer's disease in subjects aged over 65 years. This is a two-arm, parallel-design, randomized controlled trial, in which patients and assessors will be blinded. Subjects will be randomized to either an active or a sham transcranial direct current stimulation group. Participants in both groups will be evaluated at baseline, immediately, and 2 weeks after the intervention. This study investigates the safety and effect of transcranial direct current stimulation that may bring a significant impact on both depression and cognition in patients with Alzheimer's disease, and may be useful to enhance their quality of life. ClinicalTrials.gov, NCT02351388 . Registered on 27 January 2015. Last updated on 30 May 2016.

  4. 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

  5. On-chip spin-controlled orbital angular momentum directional coupling

    Science.gov (United States)

    Xie, Zhenwei; Lei, Ting; Si, Guangyuan; Du, Luping; Lin, Jiao; Min, Changjun; Yuan, Xiaocong

    2018-01-01

    Optical vortex beams have many potential applications in the particle trapping, quantum encoding, optical orbital angular momentum (OAM) communications and interconnects. However, the on-chip compact OAM detection is still a big challenge. Based on a holographic configuration and a spin-dependent structure design, we propose and demonstrate an on-chip spin-controlled OAM-mode directional coupler, which can couple the OAM signal to different directions due to its topological charge. While the directional coupling function can be switched on/off by altering the spin of incident beam. Both simulation and experimental measurements verify the validity of the proposed approach. This work would benefit the on-chip OAM devices for optical communications and high dimensional quantum coding/decoding in the future.

  6. 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

    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......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...... 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....

  7. 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%.

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

    Science.gov (United States)

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

    2013-12-01

    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.

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

    Science.gov (United States)

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

    2013-01-01

    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. PMID:24346481

  10. Experimental investigation of the direct torque neuro-fuzzy controller for induction motor drive

    Energy Technology Data Exchange (ETDEWEB)

    Grabowski, P.Z.; Kazmierkowski, M.P. [Warsaw Univ. of Technology (Poland)

    2000-08-01

    In this paper, the concept and implementation of a new simple Direct Torque Neuro-Fuzzy Control (DTNFC) scheme for PWM inverter-fed induction motor drive are presented. An Adaptive Neuro-Fuzzy Inference System (ANFIS) is applied to achieve high performance decoupled flux and torque control. The theoretical principle and tuning procedure of this method are discussed. A 3 kW induction motor experimental system with digital signal processor (DSP type) TMS 320C31 based controller has been built to verify this approach. The simulation and laboratory experimental results, which illustrate the performance of the proposed scheme, are presented. Also, nomograms for controller design are given. It has been shown that the simple DTNFC is characterised by very fast torque and flux response, very low speed operation and simple tuning capability. (orig.)

  11. 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...

  12. Investigation of high-alpha lateral-directional control power requirements for high-performance aircraft

    Science.gov (United States)

    Foster, John V.; Ross, Holly M.; Ashley, Patrick A.

    1993-01-01

    Designers of the next-generation fighter and attack airplanes are faced with the requirements of good high angle-of-attack maneuverability as well as efficient high speed cruise capability with low radar cross section (RCS) characteristics. As a result, they are challenged with the task of making critical design trades to achieve the desired levels of maneuverability and performance. This task has highlighted the need for comprehensive, flight-validated lateral-directional control power design guidelines for high angles of attack. A joint NASA/U.S. Navy study has been initiated to address this need and to investigate the complex flight dynamics characteristics and controls requirements for high angle-of-attack lateral-directional maneuvering. A multi-year research program is underway which includes groundbased piloted simulation and flight validation. This paper will give a status update of this program that will include a program overview, description of test methodology and preliminary results.

  13. 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.

  14. Adaptive Robust Motion Control of Direct-Drive DC Motors with Continuous Friction Compensation

    Directory of Open Access Journals (Sweden)

    Jianyong Yao

    2013-01-01

    Full Text Available Uncertainties including the structured and unstructured, especially the nonlinear frictions, always exist in physical servo systems and degrade their tracking accuracy. In this paper, a practical method named adaptive robust controller (ARC is synthesized with a continuous differentiable friction model for high accuracy motion control of a direct-drive dc motor, which results in a continuous control input and thus is more suitable for application. To further reduce the noise sensitivity and improve the tracking accuracy, a desired compensation version of the proposed adaptive robust controller is also developed and its stability is guaranteed by a proper robust law. The proposed controllers not only account for the structured uncertainties (e.g., parametric uncertainties but also for the unstructured uncertainties (e.g., unconsidered nonlinear frictions. Furthermore, the controllers theoretically guarantee a prescribed output tracking transient performance and final tracking accuracy in both structured and unstructured uncertainties while achieving asymptotic output tracking in the absence of unstructured uncertainties, which is very important for high accuracy control of motion systems. Extensive comparative experimental results are obtained to verify the high-performance nature of the proposed control strategies.

  15. Improvement of lithium chloride dew-point hygrometer for direct reading and controlling of relative humidity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.Z.; Chu, Y.

    1986-01-01

    The lithium chloride dew-point hygrometer has many advantages over other types of hygrometers. However, it only reads and controls the dew-point temperature of air instead of the relative humidity, which is more important in industry, agriculture, food storage, and hygiene. This paper describes a new hygrometer which is based on the same principle as the lithium chloride dew-point hygrometer, but it can read and control the relative humidity directly. The instrument is quick in response and the ranges of temperature and relative humidity are quite large. Its accuracy is normally within 3% RH and its precision is within 2% RH.

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

    KAUST Repository

    Eleiwi, Fadi; N'Doye, Ibrahima; Laleg-Kirati, Taous-Meriem

    2015-01-01

    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.

  17. Guest Editorial: Flexible Operation and Control for Medium Voltage Direct-Current (MVDC) Grid

    DEFF Research Database (Denmark)

    Li, Yong; Guerrero, Josep M.; Siano, Pierluigi

    2017-01-01

    We appreciate very much the support from the IET Power Electronics editorial board for this Special Issue on ‘Flexible Operation and Control for Medium Voltage Direct-Current (MVDC) Grid’. In this final version for publication, 15 papers have been selected for this Special Issue. Three papers...... relate to the topology of MVDC converter, four papers relate to the control of MVDC converter, four papers relate to the introduction of application fields of MVDC grid, and four papers relate to the semiconductor power device and drives towards the application in the medium- and high-voltage DC grid....

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

    International Nuclear Information System (INIS)

    Xia, Yan; Song, He-Shan

    2007-01-01

    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

  19. 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.

  20. Direct Torque Control System for Permanent Magnet Synchronous Machine with Fuzzy Speed Pi Regulator

    Science.gov (United States)

    Nabti, K.; Abed, K.; Benalla, H.

    2008-06-01

    The Permanent Magnet Synchronous Machine (PMSM) speed regulation with a conventional PI regulator reduces the speed control precision, increase the torque fluctuation, and consequentially low performances of the whole system. With utilisation of fuzzy logic method, this paper presents the self adaptation of conventional PI regulator parameters Kp and Ki (proportional and integral coefficients respectively), using to regulate the speed in Direct Torque Control strategy (DTC). The ripples of both torque and flux are reduced remarkable, small overshooting and good dynamic of the speed and torque. Simulation results verify the proposed method validity.

  1. 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.

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

    International Nuclear Information System (INIS)

    Lambert, H.E.; Lim, J.J.; Gilman, F.M.

    1978-01-01

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

  3. Designing a Fuzzy Logic Controller to Enhance Directional Stability of Vehicles under Difficult Maneuvers

    OpenAIRE

    Mehrdad N. Khajavi; Golamhassan Paygane; Ali Hakima

    2009-01-01

    Vehicle which are turning or maneuvering at high speeds are susceptible to sliding and subsequently deviate from desired path. In this paper the dynamics governing the Yaw/Roll behavior of a vehicle has been simulated. Two different simulations have been used one for the real vehicle, for which a fuzzy controller is designed to increase its directional stability property. The other simulation is for a hypothetical vehicle with much higher tire cornering stiffness which is ca...

  4. Impaired cognitive plasticity and goal-directed control in adolescent obsessive-compulsive disorder.

    Science.gov (United States)

    Gottwald, Julia; de Wit, Sanne; Apergis-Schoute, Annemieke M; Morein-Zamir, Sharon; Kaser, Muzaffer; Cormack, Francesca; Sule, Akeem; Limmer, Winifred; Morris, Anna Conway; Robbins, Trevor W; Sahakian, Barbara J

    2018-01-22

    Youths with obsessive-compulsive disorder (OCD) experience severe distress and impaired functioning at school and at home. Critical cognitive domains for daily functioning and academic success are learning, memory, cognitive flexibility and goal-directed behavioural control. Performance in these important domains among teenagers with OCD was therefore investigated in this study. A total of 36 youths with OCD and 36 healthy comparison subjects completed two memory tasks: Pattern Recognition Memory (PRM) and Paired Associates Learning (PAL); as well as the Intra-Extra Dimensional Set Shift (IED) task to quantitatively gauge learning as well as cognitive flexibility. A subset of 30 participants of each group also completed a Differential-Outcome Effect (DOE) task followed by a Slips-of-Action Task, designed to assess the balance of goal-directed and habitual behavioural control. Adolescent OCD patients showed a significant learning and memory impairment. Compared with healthy comparison subjects, they made more errors on PRM and PAL and in the first stages of IED involving discrimination and reversal learning. Patients were also slower to learn about contingencies in the DOE task and were less sensitive to outcome devaluation, suggesting an impairment in goal-directed control. This study advances the characterization of juvenile OCD. Patients demonstrated impairments in all learning and memory tasks. We also provide the first experimental evidence of impaired goal-directed control and lack of cognitive plasticity early in the development of OCD. The extent to which the impairments in these cognitive domains impact academic performance and symptom development warrants further investigation.

  5. Controlled austempering of hammer forgings aimed at pseudo normalized microstructure directly after deformation

    Directory of Open Access Journals (Sweden)

    P. Skubisz

    2017-01-01

    Full Text Available The study concerns cost-effective realization of controlled thermomechanical processing (CTMP of medium-carbon and HSLA steel aimed at producing microstructure and properties equivalent to normalized condition directly after forging. The results of theoretical and physical modeling of hot forging with subsequent heat treating adopted for industrial realization in continuous manner were verified in semi-industrial conditions of a forge plant.

  6. Composite bonded magnets with controlled anisotropy directions prepared by viscous deformation technique

    International Nuclear Information System (INIS)

    Yamashita, Fumitoshi; Kawamura, Kiyomi; Okada, Yukihiro; Murakami, Hiroshi; Ogushi, Masaki; Nakano, Masaki; Fukunaga, Hirotoshi

    2007-01-01

    When a radially anisotropic rare earth bonded magnet for a rotor with a high (BH) max value is magnetized multi-polarly, its flux distributes rectangularly and increases a cogging torque. In order to overcome this difficulty, we newly developed highly dense Sm 2 Fe 17 N 3 and Nd 2 Fe 14 B-based composite bonded magnets with continuously controlled anisotropy directions by using a viscous deformation technique

  7. Cognitive control of familiarity: directed forgetting reduces proactive interference in working memory.

    Science.gov (United States)

    Festini, Sara B; Reuter-Lorenz, Patricia A

    2014-03-01

    Proactive interference (PI) occurs when previously learned information interferes with new learning. In a working memory task, PI induces longer response times and more errors to recent negative probes than to new probes, presumably because the recent probe's familiarity invites a "yes" response. Warnings, longer intertrial intervals, and the increased contextual salience of the probes can reduce but not eliminate PI, suggesting that cognitive control over PI is limited. Here we tested whether control exerted in the form of intentional forgetting performed during working memory can reduce the magnitude of PI. In two experiments, participants performed a working memory task with directed-forgetting instructions and the occasional presentation of recent probes. Surprise long-term memory testing indicated better memory for to-be-remembered than for to-be-forgotten items, documenting the classic directed-forgetting effect. Critically, in working memory, PI was virtually eliminated for recent probes from prior to-be-forgotten lists, as compared to recent probes from prior to-be-remembered lists. Thus cognitive control, when executed via directed forgetting, can reduce the adverse and otherwise persistent interference from familiarity, an effect that we attribute to attenuated memory representations of the to-be-forgotten items.

  8. 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

  9. Frequency tuning allows flow direction control in microfluidic networks with passive features.

    Science.gov (United States)

    Jain, Rahil; Lutz, Barry

    2017-05-02

    Frequency tuning has emerged as an attractive alternative to conventional pumping techniques in microfluidics. Oscillating (AC) flow driven through a passive valve can be rectified to create steady (DC) flow, and tuning the excitation frequency to the characteristic (resonance) frequency of the underlying microfluidic network allows control of flow magnitude using simple hardware, such as an on-chip piezo buzzer. In this paper, we report that frequency tuning can also be used to control the direction (forward or backward) of the rectified DC flow in a single device. Initially, we observed that certain devices provided DC flow in the "forward" direction expected from previous work with a similar valve geometry, and the maximum DC flow occurred at the same frequency as a prominent peak in the AC flow magnitude, as expected. However, devices of a slightly different geometry provided the DC flow in the opposite direction and at a frequency well below the peak AC flow. Using an equivalent electrical circuit model, we found that the "forward" DC flow occurred at the series resonance frequency (with large AC flow peak), while the "backward" DC flow occurred at a less obvious parallel resonance (a valley in AC flow magnitude). We also observed that the DC flow occurred only when there was a measurable differential in the AC flow magnitude across the valve, and the DC flow direction was from the channel with large AC flow magnitude to that with small AC flow magnitude. Using these observations and the AC flow predictions from the equivalent circuit model, we designed a device with an AC flowrate frequency profile that was expected to allow the DC flow in opposite directions at two distinct frequencies. The fabricated device showed the expected flow reversal at the expected frequencies. This approach expands the flow control toolkit to include both magnitude and direction control in frequency-tuned microfluidic pumps. The work also raises interesting questions about the

  10. Direct adaptive fuzzy control of a translating piezoelectric flexible manipulator driven by a pneumatic rodless cylinder

    Science.gov (United States)

    Qiu, Zhi-cheng; Wang, Bin; Zhang, Xian-min; Han, Jian-da

    2013-04-01

    This study presents a novel translating piezoelectric flexible manipulator driven by a rodless cylinder. Simultaneous positioning control and vibration suppression of the flexible manipulator is accomplished by using a hybrid driving scheme composed of the pneumatic cylinder and a piezoelectric actuator. Pulse code modulation (PCM) method is utilized for the cylinder. First, the system dynamics model is derived, and its standard multiple input multiple output (MIMO) state-space representation is provided. Second, a composite proportional derivative (PD) control algorithms and a direct adaptive fuzzy control method are designed for the MIMO system. Also, a time delay compensation algorithm, bandstop and low-pass filters are utilized, under consideration of the control hysteresis and the caused high-frequency modal vibration due to the long stroke of the cylinder, gas compression and nonlinear factors of the pneumatic system. The convergence of the closed loop system is analyzed. Finally, experimental apparatus is constructed and experiments are conducted. The effectiveness of the designed controllers and the hybrid driving scheme is verified through simulation and experimental comparison studies. The numerical simulation and experimental results demonstrate that the proposed system scheme of employing the pneumatic drive and piezoelectric actuator can suppress the vibration and achieve the desired positioning location simultaneously. Furthermore, the adopted adaptive fuzzy control algorithms can significantly enhance the control performance.

  11. Direct energy balance based active disturbance rejection control for coal-fired power plant.

    Science.gov (United States)

    Sun, Li; Hua, Qingsong; Li, Donghai; Pan, Lei; Xue, Yali; Lee, Kwang Y

    2017-09-01

    The conventional direct energy balance (DEB) based PI control can fulfill the fundamental tracking requirements of the coal-fired power plant. However, it is challenging to deal with the cases when the coal quality variation is present. To this end, this paper introduces the active disturbance rejection control (ADRC) to the DEB structure, where the coal quality variation is deemed as a kind of unknown disturbance that can be estimated and mitigated promptly. Firstly, the nonlinearity of a recent power plant model is analyzed based on the gap metric, which provides guidance on how to set the pressure set-point in line with the power demand. Secondly, the approximate decoupling effect of the DEB structure is analyzed based on the relative gain analysis in frequency domain. Finally, the synthesis of the DEB based ADRC control system is carried out based on multi-objective optimization. The optimized ADRC results show that the integrated absolute error (IAE) indices of the tracking performances in both loops can be simultaneously improved, in comparison with the DEB based PI control and H ∞ control system. The regulation performance in the presence of the coal quality variation is significantly improved under the ADRC control scheme. Moreover, the robustness of the proposed strategy is shown comparable with the H ∞ control. Copyright © 2017. Published by Elsevier Ltd.

  12. 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.

  13. Direct Power Control for Three-Phase Two-Level Voltage-Source Rectifiers Based on Extended-State Observation

    DEFF Research Database (Denmark)

    Song, Zhanfeng; Tian, Yanjun; Yan, Zhuo

    2016-01-01

    This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent characte......This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent...

  14. Muscle Synergies Control during Hand-Reaching Tasks in Multiple Directions Post-stroke

    Directory of Open Access Journals (Sweden)

    Sharon Israely

    2018-02-01

    Full Text Available Purpose: A muscle synergies model was suggested to represent a simplifying motor control mechanism by the brainstem and spinal cord. The aim of the study was to investigate the feasibility of such control mechanisms in the rehabilitation of post-stroke individuals during the execution of hand-reaching movements in multiple directions, compared to non-stroke individuals.Methods: Twelve non-stroke and 13 post-stroke individuals participated in the study. Muscle synergies were extracted from EMG data that was recorded during hand reaching tasks, using the NMF algorithm. The optimal number of synergies was evaluated in both groups using the Variance Accounted For (VAF and the Mean Squared Error (MSE. A cross validation procedure was carried out to define a representative set of synergies. The similarity index and the K-means algorithm were applied to validate the existence of such a set of synergies, but also to compare the modulation properties of synergies for different movement directions between groups. The similarity index and hierarchical cluster analysis were also applied to compare between group synergies.Results: Four synergies were chosen to optimally capture the variances in the EMG data, with mean VAF of 0.917 ± 0.034 and 0.883 ± 0.046 of the data variances, with respective MSE of 0.007 and 0.016, in the control and study groups, respectively. The representative set of synergies was set to be extracted from movement to the center of the reaching space. Two synergies had different muscle activation balance between groups. Seven and 17 clusters partitioned the muscle synergies of the control and study groups. The control group exhibited a gradual change in the activation in the amplitude in the time domain (modulation of synergies, as reflected by the similarity index, whereas the study group exhibited consistently significant differences between all movement directions and the representative set of synergies. The study findings support

  15. 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.

  16. Predictive Direct Torque Control Application-Specific Integrated Circuit of an Induction Motor Drive with a Fuzzy Controller

    Directory of Open Access Journals (Sweden)

    Guo-Ming Sung

    2017-06-01

    Full Text Available This paper proposes a modified predictive direct torque control (PDTC application-specific integrated circuit (ASIC of a motor drive with a fuzzy controller for eliminating sampling and calculating delay times in hysteresis controllers. These delay times degrade the control quality and increase both torque and flux ripples in a motor drive. The proposed fuzzy PDTC ASIC calculates the stator’s magnetic flux and torque by detecting the three-phase current, three-phase voltage, and rotor speed, and eliminates the ripples in the torque and flux by using a fuzzy controller and predictive scheme. The Verilog hardware description language was used to implement the hardware architecture, and the ASIC was fabricated by the Taiwan Semiconductor Manufacturing Company through a 0.18-μm 1P6M CMOS process that involved a cell-based design method. The measurements revealed that the proposed fuzzy PDTC ASIC of the three-phase induction motor yielded a test coverage of 96.03%, fault coverage of 95.06%, chip area of 1.81 × 1.81 mm2, and power consumption of 296 mW, at an operating frequency of 50 MHz and a supply voltage of 1.8 V.

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

    International Nuclear Information System (INIS)

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

    2002-05-01

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

  18. 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

    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...... and mouldboard ploughing appear to be effective solutions against mixed stands of perennials on sandy soils but they do not comply with optimal nutrient management in organic cropping. Therefore, intensive autumn cultivation is only relevant where a perennial weed problem is uncontrollable by other means.......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...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-05-01

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

  20. Design parameters for voltage-controllable directed assembly of single nanoparticles

    International Nuclear Information System (INIS)

    Porter, Benjamin F; Bhaskaran, Harish; Abelmann, Leon

    2013-01-01

    Techniques to reliably pick-and-place single nanoparticles into functional assemblies are required to incorporate exotic nanoparticles into standard electronic circuits. In this paper we explore the use of electric fields to drive and direct the assembly process, which has the advantage of being able to control the nano-assembly process at the single nanoparticle level. To achieve this, we design an electrostatic gating system, thus enabling a voltage-controllable nanoparticle picking technique. Simulating this system with the nonlinear Poisson–Boltzmann equation, we can successfully characterize the parameters required for single particle placement, the key being single particle selectivity, in effect designing a system that can achieve this controllably. We then present the optimum design parameters required for successful single nanoparticle placement at ambient temperature, an important requirement for nanomanufacturing processes. (paper)

  1. Reversing the direction of galvanotaxis with controlled increases in boundary layer viscosity

    Science.gov (United States)

    Kobylkevich, Brian M.; Sarkar, Anyesha; Carlberg, Brady R.; Huang, Ling; Ranjit, Suman; Graham, David M.; Messerli, Mark A.

    2018-05-01

    Weak external electric fields (EFs) polarize cellular structure and direct most migrating cells (galvanotaxis) toward the cathode, making it a useful tool during tissue engineering and for healing epidermal wounds. However, the biophysical mechanisms for sensing weak EFs remain elusive. We have reinvestigated the mechanism of cathode-directed water flow (electro-osmosis) in the boundary layer of cells, by reducing it with neutral, viscous polymers. We report that increasing viscosity with low molecular weight polymers decreases cathodal migration and promotes anodal migration in a concentration dependent manner. In contrast, increased viscosity with high molecular weight polymers does not affect directionality. We explain the contradictory results in terms of porosity and hydraulic permeability between the polymers rather than in terms of bulk viscosity. These results provide the first evidence for controlled reversal of galvanotaxis using viscous agents and position the field closer to identifying the putative electric field receptor, a fundamental, outside-in signaling receptor that controls cellular polarity for different cell types.

  2. 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

  3. The control of the upstream movement of fish with pulsated direct current

    Science.gov (United States)

    McLain, Alberton L.

    1957-01-01

    Alternating-current electromechanical devices installed in the mouths of streams have proved effective in stopping the spawning migrations of the parasitic sea lamprey (Petromyzon marinus) which has seriously damaged Great Lakes fisheries. In a few streams, excessive mortality has occurred to other fish at the alternating-current barriers. A direct-current unit was developed in an attempt to reduce this mortality. This direct-current “diversion device” consists of a row of suspended negative electrodes which begins at the end of a trap wing and extends across the river at a downstream angle of 45° and a series of pipes (positive electrodes) driven into the stream bank. A second array, consisting of horizontal pipes installed downstream and parallel to the suspended electrodes and connected to a series of rods driven into the bank near the positive electrodes, controls the electrical field and dissipates the collecting influence of the positive side of the circuit. The electrical field is established from the end of the trap wing to the opposite bank. Fish are diverted away from the negative electrodes and toward the bank near which the trap is located. The array is activiated by pulsated direct current of essentially square wave shape with pulses at a duty cycle of 0.66 and a repetition rate of 3 per second. Direct-current diversion devices were operated in conjunction with alternating-current barriers during 1956 in the Chocolay River, Marquette County, and the Silver River, Baraga County, Michigan.

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

    International Nuclear Information System (INIS)

    Matsukizono, Hiroyuki; Jin, Ren-Hua

    2011-01-01

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

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

    International Nuclear Information System (INIS)

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

    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 and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices. (focus issue paper)

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

    Science.gov (United States)

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

    2015-07-01

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

  7. Apathy and impulse control disorders in Parkinson's disease: a direct comparison.

    Science.gov (United States)

    Leroi, Iracema; Andrews, Michelle; McDonald, Kathryn; Harbishettar, Vijay; Elliott, Rebecca; Byrne, E Jane; Burns, Alistair

    2012-02-01

    Apathy and impulse control disorders (ICDs) in Parkinson's disease (PD) are clinically important complications and may exist on a common behavioral spectrum of disorders of reward and motivation. To directly compare PD participants with apathy those with ICDs on range of demographic, neurologic and psychiatric measures. Ninety-nine non-demented PD participants (ICD, n = 35; apathy, n = 26; and controls, n = 38) were assessed in the study. Univariate statistics were used to compare the behavioral groups. A linear regression model was created with either apathy or impulsivity as the dependent variable. The two behavioral groups differed significantly from the PD control group on similar factors but in opposite directions. The apathy group was older at the time of both assessment and disease onset, had higher levels of depression and lower dopamine agonist use, compared to the other two groups. The ICD group was younger than the apathy group at disease onset and had higher levels of anxiety, a higher overall dopamine load and greater motor disease complexity. Overlap in behavioral pathology across the two groups was also noted. Apathy and ICDs may be on a common behavioral spectrum in PD. Both are associated with significant psychiatric morbidity supporting shared underlying pathology. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Alba Diz-Muñoz

    2010-11-01

    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.

  9. 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...

  10. Steady flow torques in a servo motor operated rotary directional control valve

    International Nuclear Information System (INIS)

    Wang, He; Gong, Guofang; Zhou, Hongbin; Wang, Wei

    2016-01-01

    Highlights: • A novel servo motor operated rotary directional control valve is proposed. • Steady flow torque is a crucial issue that affects rotary valve performance. • Steady flow torque is analyzed on the aspects of theory, simulation and experiment. • Change law of the steady flow torque with spool rotation angle is explored. • Effect of pressure drop and flow rate on the steady flow torque is studied. - Abstract: In this paper, a servo motor operated rotary directional control valve is proposed, and a systematic analysis of steady flow torques in this valve is provided by theoretical calculation, CFD simulation and experimental test. In the analysis, spool rotation angle corresponding to the maximum orifice opening is tagged as 0°. Over a complete change cycle of the orifice, the range of spool rotation angle is symmetric about 0°. The results show that the direction of steady flow torques in this valve is always the direction of orifice closing. The steady flow torques serve as resistances to the spool rotation when the orifice opening increases, while impetuses to the spool rotation when the orifice opening decreases. At a certain pressure drop or flow rate, steady flow torques are approximately equal and opposite when at spool rotation angles which are symmetric about 0°. When the spool rotates from 0°, at a certain pressure drop, their values increase first then decrease with the spool rotation and reach their maximum values at an angle corresponding to about 1/2 of the maximum orifice opening, and at a certain flow rate, their values increase with the spool rotation. The steady flow torques in this valve are the sums of those in the meter-in and meter-out valve chambers. At a certain spool rotation angle, steady flow torques in the meter-in and meter-out valve chambers are approximately proportional to the pressure drop and the second power of the flow rate through the orifice. Theoretical calculation and CFD simulation can be validated by

  11. Pinning synchronization of hybrid-coupled directed delayed dynamical network via intermittent control.

    Science.gov (United States)

    Cai, Shuiming; Zhou, Peipei; Liu, Zengrong

    2014-09-01

    This paper concerns the problem of exponential synchronization for a class of general delayed dynamical networks with hybrid coupling via pinning periodically intermittent control. Both the internal delay and coupling delay are taken into account in the network model. Meanwhile, the transmission delay and self-feedback delay are involved in the delayed coupling term. By establishing a new differential inequality, several simple and useful exponential synchronization criteria are derived analytically. It is shown that the controlled synchronization state can vary in comparison with the conventional synchronized solution, and the degree of the node and the inner delayed coupling matrix play important roles in the controlled synchronization state. By choosing different inner delayed coupling matrices and the degrees of the node, different controlled synchronization states can be obtained. Furthermore, the detail pinning schemes deciding what nodes should be chosen as pinned candidates and how many nodes are needed to be pinned for a fixed coupling strength are provided. The simple procedures illuminating how to design suitable intermittent controllers in real application are also given. Numerical simulations, including an undirected scale-free network and a directed small-world network, are finally presented to demonstrate the effectiveness of the theoretical results.

  12. 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.

  13. Critical Roles of the Direct GABAergic Pallido-cortical Pathway in Controlling Absence Seizures

    Science.gov (United States)

    Li, Min; Ma, Tao; Wu, Shengdun; Ma, Jingling; Cui, Yan; Xia, Yang; Xu, Peng; Yao, Dezhong

    2015-01-01

    The basal ganglia (BG), serving as an intermediate bridge between the cerebral cortex and thalamus, are believed to play crucial roles in controlling absence seizure activities generated by the pathological corticothalamic system. Inspired by recent experiments, here we systematically investigate the contribution of a novel identified GABAergic pallido-cortical pathway, projecting from the globus pallidus externa (GPe) in the BG to the cerebral cortex, to the control of absence seizures. By computational modelling, we find that both increasing the activation of GPe neurons and enhancing the coupling strength of the inhibitory pallido-cortical pathway can suppress the bilaterally synchronous 2–4 Hz spike and wave discharges (SWDs) during absence seizures. Appropriate tuning of several GPe-related pathways may also trigger the SWD suppression, through modulating the activation level of GPe neurons. Furthermore, we show that the previously discovered bidirectional control of absence seizures due to the competition between other two BG output pathways also exists in our established model. Importantly, such bidirectional control is shaped by the coupling strength of this direct GABAergic pallido-cortical pathway. Our work suggests that the novel identified pallido-cortical pathway has a functional role in controlling absence seizures and the presented results might provide testable hypotheses for future experimental studies. PMID:26496656

  14. 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.

  15. Deficiencies in product labelling instructions and quality control directions for 99mTc radiopharmaceuticals.

    Science.gov (United States)

    Buroni, Federica E; Lodola, Lorenzo; Persico, Marco G; Aprile, Carlo

    2014-02-01

    The aim of the study was to identify deficiencies in product labelling instructions for reconstitution and in the quality control directions detailed in the technical leaflets (TLs) or summary product characteristic (SPC) sheets of commonly used technetium labelling cold kits. The reconstitution and quality control directions in 25 TLs/SPCs were evaluated to identify deficiencies, incompleteness, restrictions, errors, impracticability, and vagueness. In addition, their congruence with the statements given in the relative European Pharmacopoeia (Ph. Eur. VII ed.) monography and diagnostic reference levels of Directive 97/43/EURATOM was evaluated. Deficiencies in information were scored and classified into five categories: 1, absent or incomplete; 2, restrictive; 3, inconsistent or wrong; 4, impractical; and 5, vague. In the 25 documents analyzed a total of 141 deficiencies were found (corresponding to 40.2% of the total scores assigned), and more frequently they pertained to quality control procedures (70.9%), followed by those related to quantitative composition (14.9%), preparation (8.5%), and particle size (5.7%). Nearly 80% of these deficiencies were classified as type 1 - that is, absent or incomplete information. The indications in TLs and SPCs should provide useful information for maintaining the quality and purity of the radiopharmaceutical preparation and ensure the safety level and effectiveness required by law. However, the instructions are often suboptimal or even erroneous, and consequently there are countless failures or difficulties, which represent an impediment to good laboratory practice. We believe that a 'smart' review of radiopharmaceutical documentation would be beneficial in order to align these indications to the real needs of the operators involved in routine in-house nuclear medicine practice.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

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

  17. 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.

  18. 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

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

    International Nuclear Information System (INIS)

    Yang, Chun-Wei; Hwang, Tzonelih; Tsai, Chia-Wei

    2014-01-01

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

  20. In situ exposure to non-directional beacons for air traffic control.

    Science.gov (United States)

    Joseph, Wout; Goeminne, Francis; Vermeeren, Günter; Verloock, Leen; Martens, Luc

    2012-04-01

    In situ electromagnetic field exposure of workers and the general public due to non-directional beacons (NDB) for air traffic control is assessed and characterized. For occupational exposure, the maximal measured electric field value is 881.6 V/m and the maximal magnetic field value is 9.1 A/m. The maximum electric fields exceed the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels at all seven NDB sites, and the magnetic fields at two of the seven NDB sites (occupational exposure). Recommendations and compliance distances for workers and the general public are provided. © 2012 Wiley Periodicals, Inc.

  1. Comparison and extension of a direct model reference adaptive control procedure

    Science.gov (United States)

    Neat, Gregory W.; Kaufman, Howard; Steinvorth, Rodrigo

    1992-01-01

    This paper analyzes and extends an easily implemented direct model reference adaptive control procedure. The paper focuses on the major limitation of this control approach which is the satisfaction of a strictly positive real sufficiency condition in order to guarantee asymptotic tracking. Attempts, to date, to address this problem have been unable to relax simultaneously the stringent condition and maintain asymptotic tracking capabilities. Three different modifications to existing versions of this algorithm are presented which substantially relax the stringent sufficiency condition while providing asymptotic tracking. These three modifications achieve this goal by imposing slight adjustments to existing sufficiency conditions. A simulation example demonstrates that the modifications eliminate the steady error inherent in the existing methods.

  2. Path tracking control of an omni-directional walker considering pressures from a user.

    Science.gov (United States)

    Tan, Renpeng; Wang, Shuoyu; Jiang, Yinlai; Ishida, Kenji; Fujie, Masakatsu G

    2013-01-01

    An omni-directional walker (ODW) is being developed to support the people with walking disabilities to do walking rehabilitation. The training paths, which the user follows in the rehabilitation, are defined by physical therapists and stored in the ODW. In order to obtain a good training effect, the defined training paths need to be performed accurately. However, the ODW deviates from the training path in real rehabilitation, which is caused by the variation of the whole system's parameters due to the force from the user. In this paper, the characteristics of pressures from a user are measured, based on which an adaptive controller is proposed to deal with this problem, and validated in an experiment in which a pseudo handicapped person follows the ODW. The experimental results show that the proposed method can control the ODW to accurately follow the defined path with or without a user.

  3. Wheels Optimization and Vision Control of Omni-directional Mobile Microrobot

    Directory of Open Access Journals (Sweden)

    Jianghao Li

    2008-06-01

    Full Text Available This paper presents a millimeters scale omni-directional mobile microrobot with special dual-wheel structure. The microrobot was actuated by three electromagnetic micromotors of 2mm diameter. Dynamic analysis of translational and steering movements presented the relationship between the sizes of the dual-wheel structure and the output torque of the micromotor. Genetic algorithm (GA was employed to optimize the dual-wheel's sizes for reducing the unnecessary torque consumption and improving the driving ability of the microrobot. A computer vision system contained two sets of feedback control is devised for the microrobot. Torque self-balance and current-limiting control approach are presented to ensure the accuracy of step movement. Experiment results demonstrate the feasibility of these concepts.

  4. Wheels Optimization and Vision Control of Omni-directional Mobile Microrobot

    Directory of Open Access Journals (Sweden)

    Jianghao Li

    2008-11-01

    Full Text Available This paper presents a millimeters scale omni-directional mobile microrobot with special dual-wheel structure. The microrobot was actuated by three electromagnetic micromotors of 2mm diameter. Dynamic analysis of translational and steering movements presented the relationship between the sizes of the dual-wheel structure and the output torque of the micromotor. Genetic algorithm (GA was employed to optimize the dualwheel's sizes for reducing the unnecessary torque consumption and improving the driving ability of the microrobot. A computer vision system contained two sets of feedback control is devised for the microrobot. Torque self-balance and current-limiting control approach are presented to ensure the accuracy of step movement. Experiment results demonstrate the feasibility of these concepts.

  5. 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.

  6. 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

  7. A novel neural-net-based nonlinear adaptive control and application to the cross-direction deviations control of a polymer film spread line

    International Nuclear Information System (INIS)

    Chen Zengqiang; Li Xiang; Liu Zhongxin; Yuan Zhuzhi

    2008-01-01

    A novel neural adaptive controller is presented to effectively control multivariable nonlinear systems. The proposed neural controller has been successfully applied to the cross-direction deviation control system of a polymer film spread line, whose good performance has been verified with real-time running results

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

    International Nuclear Information System (INIS)

    Dias, A D; Corr, D T; Unser, A M; Xie, Y; Chrisey, D B

    2014-01-01

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

  9. 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.

  10. Experimental study on control performance of tuned liquid column dampers considering different excitation directions

    Science.gov (United States)

    Altunişik, Ahmet Can; Yetişken, Ali; Kahya, Volkan

    2018-03-01

    This paper gives experimental tests' results for the control performance of Tuned Liquid Column Dampers (TLCDs) installed on a prototype structure exposed to ground motions with different directions. The prototype structure designed in the laboratory consists of top and bottom plates with four columns. Finite element analyses and ambient vibration tests are first performed to extract the natural frequencies and mode shapes of the structure. Then, the damping ratio of the structure as well as the resonant frequency, head-loss coefficient, damping ratio, and water height-frequency diagram of the designed TLCD are obtained experimentally by the shaking table tests. To investigate the effect of TLCDs on the structural response, the prototype structure-TLCD coupled system is considered later, and its natural frequencies and related mode shapes are obtained numerically. The acceleration and displacement time-histories are obtained by the shaking table tests to evaluate its damping ratio. To consider different excitation directions, the measurements are repeated for the directions between 0° and 90° with 15° increment. It can be concluded from the study that TLCD causes to decrease the resonant frequency of the structure with increasing of the total mass. Damping ratio considerably increases with installing TLCD on the structure. This is more pronounced for the angles of 0°, 15°, 30° and 45°.

  11. A randomized controlled trial of directive and nondirective smoking cessation coaching through an employee quitline

    Directory of Open Access Journals (Sweden)

    Walton Sumner

    2016-07-01

    Full Text Available Abstract Background Telephone quitlines can help employees quit smoking. Quitlines typically use directive coaching, but nondirective, flexible coaching is an alternative. Call-2-Quit used a worksite-sponsored quitline to compare directive and nondirective coaching modes, and evaluated employee race and income as potential moderators. Methods An unblinded randomized controlled trial compared directive and nondirective telephone coaching by trained laypersons. Participants were smoking employees and spouses recruited through workplace smoking cessation campaigns in a hospital system and affiliated medical school. Coaches were four non-medical women trained to use both coaching modes. Participants were randomized by family to coaching mode. Participants received up to 7 calls from coaches who used computer assisted telephone interview software to track topics and time. Outcomes were reported smoking abstinence for 7 days at last contact, 6 or 12 months after coaching began. Both worksites implemented new tobacco control policies during the study. Results Most participants responded to an insurance incentive introduced at the hospital. Call-2-Quit coached 518 participants: 22 % were African-American; 45 % had incomes below $30,000. Income, race, and intervention did not affect coaching completion rates. Cessation rates were comparable with directive and nondirective coaching (26 % versus 30 % quit, NS. A full factorial logistic regression model identified above median income (odds ratio = 1.8, p = 0.02, especially among African Americans (p = 0.04, and recent quit attempts (OR = 1.6, p = 0.03 as predictors of cessation. Nondirective coaching was associated with high cessation rates among subgroups of smokers reporting income above the median, recent quit attempts, or use of alternative therapies. Waiting up to 4 weeks to start coaching did not affect cessation. Of 41 highly addicted or depressed smokers who had never quit

  12. A randomized controlled trial of directive and nondirective smoking cessation coaching through an employee quitline.

    Science.gov (United States)

    Sumner, Walton; Walker, Mark S; Highstein, Gabrielle R; Fischer, Irene; Yan, Yan; McQueen, Amy; Fisher, Edwin B

    2016-07-11

    Telephone quitlines can help employees quit smoking. Quitlines typically use directive coaching, but nondirective, flexible coaching is an alternative. Call-2-Quit used a worksite-sponsored quitline to compare directive and nondirective coaching modes, and evaluated employee race and income as potential moderators. An unblinded randomized controlled trial compared directive and nondirective telephone coaching by trained laypersons. Participants were smoking employees and spouses recruited through workplace smoking cessation campaigns in a hospital system and affiliated medical school. Coaches were four non-medical women trained to use both coaching modes. Participants were randomized by family to coaching mode. Participants received up to 7 calls from coaches who used computer assisted telephone interview software to track topics and time. Outcomes were reported smoking abstinence for 7 days at last contact, 6 or 12 months after coaching began. Both worksites implemented new tobacco control policies during the study. Most participants responded to an insurance incentive introduced at the hospital. Call-2-Quit coached 518 participants: 22 % were African-American; 45 % had incomes below $30,000. Income, race, and intervention did not affect coaching completion rates. Cessation rates were comparable with directive and nondirective coaching (26 % versus 30 % quit, NS). A full factorial logistic regression model identified above median income (odds ratio = 1.8, p = 0.02), especially among African Americans (p = 0.04), and recent quit attempts (OR = 1.6, p = 0.03) as predictors of cessation. Nondirective coaching was associated with high cessation rates among subgroups of smokers reporting income above the median, recent quit attempts, or use of alternative therapies. Waiting up to 4 weeks to start coaching did not affect cessation. Of 41 highly addicted or depressed smokers who had never quit more than 30 days, none quit. Nondirective

  13. Light-controlled motility in prokaryotes and the problem of directional light perception.

    Science.gov (United States)

    Wilde, Annegret; Mullineaux, Conrad W

    2017-11-01

    The natural light environment is important to many prokaryotes. Most obviously, phototrophic prokaryotes need to acclimate their photosynthetic apparatus to the prevailing light conditions, and such acclimation is frequently complemented by motility to enable cells to relocate in search of more favorable illumination conditions. Non-phototrophic prokaryotes may also seek to avoid light at damaging intensities and wavelengths, and many prokaryotes with diverse lifestyles could potentially exploit light signals as a rich source of information about their surroundings and a cue for acclimation and behavior. Here we discuss our current understanding of the ways in which bacteria can perceive the intensity, wavelength and direction of illumination, and the signal transduction networks that link light perception to the control of motile behavior. We discuss the problems of light perception at the prokaryotic scale, and the challenge of directional light perception in small bacterial cells. We explain the peculiarities and the common features of light-controlled motility systems in prokaryotes as diverse as cyanobacteria, purple photosynthetic bacteria, chemoheterotrophic bacteria and haloarchaea. © FEMS 2017.

  14. Nonlinear Least Square Based on Control Direction by Dual Method and Its Application

    Directory of Open Access Journals (Sweden)

    Zhengqing Fu

    2016-01-01

    Full Text Available A direction controlled nonlinear least square (NLS estimation algorithm using the primal-dual method is proposed. The least square model is transformed into the primal-dual model; then direction of iteration can be controlled by duality. The iterative algorithm is designed. The Hilbert morbid matrix is processed by the new model and the least square estimate and ridge estimate. The main research method is to combine qualitative analysis and quantitative analysis. The deviation between estimated values and the true value and the estimated residuals fluctuation of different methods are used for qualitative analysis. The root mean square error (RMSE is used for quantitative analysis. The results of experiment show that the model has the smallest residual error and the minimum root mean square error. The new estimate model has effectiveness and high precision. The genuine data of Jining area in unwrapping experiments are used and the comparison with other classical unwrapping algorithms is made, so better results in precision aspects can be achieved through the proposed algorithm.

  15. Differentiating neural systems mediating the acquisition versus expression of goal-directed and habitual behavioral control

    Science.gov (United States)

    Liljeholm, Mimi; Dunne, Simon; O'Doherty, John P.

    2015-01-01

    Considerable behavioral data indicates that operant actions can become habitual, as evidenced by insensitivity to changes in the action-outcome contingency and in subjective outcome values. Notably, although several studies have investigated the neural substrates of habits, none has clearly differentiated the areas of the human brain that support habit formation from those that implement habitual control. We scanned participants with fMRI as they learned and performed an operant task in which the conditional structure of the environment encouraged either goal-directed encoding of the consequences of actions, or a habit-like mapping of actions to antecedent cues. Participants were also scanned during a subsequent assessment of insensitivity to outcome devaluation. We identified dissociable roles of the cerebellum and ventral striatum, across learning and test performance, in behavioral insensitivity to outcome devaluation. We also show that the inferior parietal lobule – an area previously implicated in several aspects of goal-directed action selection, including the attribution of intent and awareness of agency – predicts sensitivity to outcome devaluation. Finally, we reveal a potential functional homology between the human subgenual cortex and rodent infralimbic cortex in the implementation of habitual control. In summary, our findings suggest a broad systems division, at the cortical and subcortical levels, between brain areas mediating the encoding and expression of action-outcome and stimulus-response associations. PMID:25892332

  16. 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

  17. 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.

  18. Nonlinear Robust Control for Low Voltage Direct-Current Residential Microgrids with Constant Power Loads

    Directory of Open Access Journals (Sweden)

    Martín-Antonio Rodríguez-Licea

    2018-05-01

    Full Text Available A Direct Current (DC microgrid is a concept derived from a smart grid integrating DC renewable sources. The DC microgrids have three particularities: (1 integration of different power sources and local loads through a DC link; (2 on-site power source generation; and (3 alternating loads (on-off state. This kind of arrangement achieves high efficiency, reliability and versatility characteristics. The key device in the development of the DC microgrid is the power electronic converter (PEC, since it allows an efficient energy conversion between power sources and loads. However, alternating loads with strictly-controlled PECs can provide negative impedance behavior to the microgrid, acting as constant power loads (CPLs, such that the overall closed-loop system becomes unstable. Traditional CPL compensation techniques rely on a damping increment by the adaptation of the source or load voltage level, adding external circuitry or by using some advanced control technique. However, none of them provide a simple and general solution for the CPL problem when abrupt changes in parameters and/or in alternating loads/sources occur. This paper proposes a mathematical modeling and a robust control for the basic PECs dealing with CPLs in continuous conduction mode. In particular, the case of the low voltage residential DC microgrid with CPLs is taken as a benchmark. The proposed controller can be easily tuned for the desired response even by the non-expert. Basic converters with voltage mode control are taken as a basis to show the feasibility of this analysis, and experimental tests on a 100-W testbed include abrupt parameter changes such as input voltage.

  19. Preliminary study on the control of direct injection diesel engine for better fuel flexibility and emissions control. Pt. 3

    Energy Technology Data Exchange (ETDEWEB)

    Egnell, R.; Kassem, N.; Bohlin, T.

    1985-01-01

    This report summarizes the results of a preliminary study on turbocharged direct injection diesel engines. The objectives and scope of this study are: 1. To explore the potential of using electronic control systems based on dynamic models of the engine in order to reduce fuel consumption, while maintaining good driveability. 2. To analyze the transient response of a turbocharged diesel engine based on experimental data collected from one of SAAB-SCANIA's test cells. 3. To survey the hardware components that would satisfy the requirements of the electronic control systems mentioned above. Part III discusses the transient response measurements obtained from two sets of experiments conducted on a six-cylinder motor working under varying conditions of load and speed. The objective of the first set of experiments was to quantify the difference in ignition delay between the transient and steady state operating conditions. The second set of experiments were aimed to provide a basis on which the engine efficiency obtained under transient conditions can be compared to that obtained from a single-cylinder motor working under steady state conditions.

  20. 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

  1. 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

  2. Molecular inspired models for prediction and control of directional FSO/RF wireless networks

    Science.gov (United States)

    Llorca, Jaime; Milner, Stuart D.; Davis, Christopher C.

    2010-08-01

    Directional wireless networks using FSO and RF transmissions provide wireless backbone support for mobile communications in dynamic environments. The heterogeneous and dynamic nature of such networks challenges their robustness and requires self-organization mechanisms to assure end-to-end broadband connectivity. We developed a framework based on the definition of a potential energy function to characterize robustness in communication networks and the study of first and second order variations of the potential energy to provide prediction and control strategies for network performance optimization. In this paper, we present non-convex molecular potentials such as the Morse Potential, used to describe the potential energy of bonds within molecules, for the characterization of communication links in the presence of physical constraints such as the power available at the network nodes. The inclusion of the Morse Potential translates into adaptive control strategies where forces on network nodes drive the release, retention or reconfiguration of communication links for network performance optimization. Simulation results show the effectiveness of our self-organized control mechanism, where the physical topology reorganizes to maximize the number of source to destination communicating pairs. Molecular Normal Mode Analysis (NMA) techniques for assessing network performance degradation in dynamic networks are also presented. Preliminary results show correlation between peaks in the eigenvalues of the Hessian of the network potential and network degradation.

  3. Direct modulation of T-box riboswitch-controlled transcription by protein synthesis inhibitors.

    Science.gov (United States)

    Stamatopoulou, Vassiliki; Apostolidi, Maria; Li, Shuang; Lamprinou, Katerina; Papakyriakou, Athanasios; Zhang, Jinwei; Stathopoulos, Constantinos

    2017-09-29

    Recently, it was discovered that exposure to mainstream antibiotics activate numerous bacterial riboregulators that control antibiotic resistance genes including metabolite-binding riboswitches and other transcription attenuators. However, the effects of commonly used antibiotics, many of which exhibit RNA-binding properties, on the widespread T-box riboswitches, remain unknown. In Staphylococcus aureus, a species-specific glyS T-box controls the supply of glycine for both ribosomal translation and cell wall synthesis, making it a promising target for next-generation antimicrobials. Here, we report that specific protein synthesis inhibitors could either significantly increase T-box-mediated transcription antitermination, while other compounds could suppress it, both in vitro and in vivo. In-line probing of the full-length T-box combined with molecular modelling and docking analyses suggest that the antibiotics that promote transcription antitermination stabilize the T-box:tRNA complex through binding specific positions on stem I and the Staphylococcal-specific stem Sa. By contrast, the antibiotics that attenuate T-box transcription bind to other positions on stem I and do not interact with stem Sa. Taken together, our results reveal that the transcription of essential genes controlled by T-box riboswitches can be directly modulated by commonly used protein synthesis inhibitors. These findings accentuate the regulatory complexities of bacterial response to antimicrobials that involve multiple riboregulators. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  4. Thickness-controlled direct growth of nanographene and nanographite film on non-catalytic substrates

    Science.gov (United States)

    Du, Lei; Yang, Liu; Hu, Zhiting; Zhang, Jiazhen; Huang, Chunlai; Sun, Liaoxin; Wang, Lin; Wei, Dacheng; Chen, Gang; Lu, Wei

    2018-05-01

    Metal-catalyzed chemical vapor deposition (CVD) has been broadly employed for large-scale production of high-quality graphene. However, a following transfer process to targeted substrates is needed, which is incompatible with current silicon technology. We here report a new CVD approach to form nanographene and nanographite films with accurate thickness control directly on non-catalytic substrates such as silicon dioxide and quartz at 800 °C. The growth time is as short as a few seconds. The approach includes using 9-bis(diethylamino)silylanthracene as the carbon source and an atomic layer deposition (ALD) controlling system. The structure of the formed nanographene and nanographite films were characterized using atomic force microscopy, high resolution transmission electron microscopy, Raman scattering, and x-ray photoemission spectroscopy. The nanographite film exhibits a transmittance higher than 80% at 550 nm and a sheet electrical resistance of 2000 ohms per square at room temperature. A negative temperature-dependence of the resistance of the nanographite film is also observed. Moreover, the thickness of the films can be precisely controlled via the deposition cycles using an ALD system, which promotes great application potential for optoelectronic and thermoelectronic-devices.

  5. 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.

  6. Full impact of laboratory information system requires direct use by clinical staff: cluster randomized controlled trial.

    Science.gov (United States)

    Blaya, Joaquín A; Shin, Sonya; Contreras, Carmen; Yale, Gloria; Suarez, Carmen; Asencios, Luis; Kim, Jihoon; Rodriguez, Pablo; Cegielski, Peter; Fraser, Hamish S F

    2011-01-01

    To evaluate the time to communicate laboratory results to health centers (HCs) between the e-Chasqui web-based information system and the pre-existing paper-based system. Cluster randomized controlled trial in 78 HCs in Peru. In the intervention group, 12 HCs had web access to results via e-Chasqui (point-of-care HCs) and forwarded results to 17 peripheral HCs. In the control group, 22 point-of-care HCs received paper results directly and forwarded them to 27 peripheral HCs. Baseline data were collected for 15 months. Post-randomization data were collected for at least 2 years. Comparisons were made between intervention and control groups, stratified by point-of-care versus peripheral HCs. For point-of-care HCs, the intervention group took less time to receive drug susceptibility tests (DSTs) (median 9 vs 16 days, p60 days to arrive (pChasqui information system had reduced communication times and fewer results with delays of >2 months. Peripheral HCs had no benefits from the system. This suggests that health establishments should have point-of-care access to reap the benefits of electronic laboratory reporting.

  7. Distributed adaptive asymptotically consensus tracking control of uncertain Euler-Lagrange systems under directed graph condition.

    Science.gov (United States)

    Wang, Wei; Wen, Changyun; Huang, Jiangshuai; Fan, Huijin

    2017-11-01

    In this paper, a backstepping based distributed adaptive control scheme is proposed for multiple uncertain Euler-Lagrange systems under directed graph condition. The common desired trajectory is allowed totally unknown by part of the subsystems and the linearly parameterized trajectory model assumed in currently available results is no longer needed. To compensate the effects due to unknown trajectory information, a smooth function of consensus errors and certain positive integrable functions are introduced in designing virtual control inputs. Besides, to overcome the difficulty of completely counteracting the coupling terms of distributed consensus errors and parameter estimation errors in the presence of asymmetric Laplacian matrix, extra information transmission of local parameter estimates are introduced among linked subsystem and adaptive gain technique is adopted to generate distributed torque inputs. It is shown that with the proposed distributed adaptive control scheme, global uniform boundedness of all the closed-loop signals and asymptotically output consensus tracking can be achieved. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

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

    International Nuclear Information System (INIS)

    Kim, Woo Jin; Kim, Jae Kwang

    2014-01-01

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

  10. 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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

    Barut, Murat; Bogosyan, Seta; Gokasan, Metin

    2005-01-01

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

  12. Controlled disulfonated poly(arylene ether sulfone) multiblock copolymers for direct methanol fuel cells.

    Science.gov (United States)

    Li, Qing; Chen, Yu; Rowlett, Jarrett R; McGrath, James E; Mack, Nathan H; Kim, Yu Seung

    2014-04-23

    Structure-property-performance relationships of disulfonated poly(arylene ether sulfone) multiblock copolymer membranes were investigated for their use in direct methanol fuel cell (DMFC) applications. Multiple series of reactive polysulfone, polyketone, and polynitrile hydrophobic block segments having different block lengths and molecular composition were synthesized and reacted with a disulfonated poly(arylene ether sulfone) hydrophilic block segment by a coupling reaction. Large-scale morphological order of the multiblock copolymers evolved with the increase of block size that gave notable influence on mechanical toughness, water uptake, and proton/methanol transport. Chemical structural changes of the hydrophobic blocks through polar group, fluorination, and bisphenol type allowed further control of the specific properties. DMFC performance was analyzed to elicit the impact of structural variations of the multiblock copolymers. Finally, DMFC performances of selected multiblock copolymers were compared against that of the industrial standard Nafion in the DMFC system.

  13. Direct Monitoring and Control of Transformer Temperature in Order to Avoid its Breakdown Using FOS

    Directory of Open Access Journals (Sweden)

    Deepika YADAV

    2008-09-01

    Full Text Available This manuscript focuses on Direct Monitoring & Control of Transformer Temperature in order to avoid its Breakdown Using FOS (fiber optic sensor. Although there are various reasons for failure of transformer operation but mainly it is due to conductor loss and hysteresis losses which causes temperature rise in the internal structures of the transformer leading to burning of windings. A system for monitoring the temperature of transformers is required. Existing sensors cannot be used for monitoring the temperature of transformers because they are sensitive to electrical signals and can cause sparking which can trigger fire since there is oil in transformers cooling coils. Distributed FOS based on microbend is simulated on MATLAB7.5 in order to check the effectiveness of this sensor. Results in the form of graphs i.e., intensity modulation vs. the temperature has been shown in the manuscript.

  14. Direct labeling of doxorubicin with technetium-99m. Its optimization, characterization and quality control

    International Nuclear Information System (INIS)

    Rizvi, F.A.; Bokhari, T.H.; Roohi, S.; Mushtaq, A.

    2012-01-01

    Doxorubicin (DOX) is an anthracycline antineoplastic and one of the most potent and widely used drugs in clinical oncology. It is used in the treatment of a wide variety of cancers. The aim of this study was the direct labeling of DOX with 99m Tc; its optimization, characterization and quality control of the radiolabeled DOX. Labeling efficiency was determined by paper chromatography. More than 92% labeling was obtained at pH 6-7, 10-12 μg stannous chloride and 200 μg of DOX. The stability of 99m Tc-DOX was studied up to 5 h. All the experiments were performed at room temperature (25 ± 2 deg C). The characterization of the labeling compound was performed by HPLC and electrophoresis. Electrophoresis indicates that labeled DOX has no charge and HPLC shows single specie of labeled compound. (author)

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

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh

    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...... of inductorless switch-mode power supplies employing piezoelectric transformers. The main focus of this research is on the functionality of the piezoelectric transformer-based power converters and applying control techniques in order to exploit advantages of the piezoelectric transformers for the power converters...... detector applicable for switch-mode power supplies, optimum phase detector, bi-directional wide bandwidth current sensor and a comprehensive analysis of piezoelectric transformer-based switch-mode power supplies for zero-voltage switching, where all finalized with improving the unidirectional topology...

  16. A Community-Directed Integrated Strongyloides Control Program in Queensland, Australia

    Directory of Open Access Journals (Sweden)

    Adrian Miller

    2018-05-01

    Full Text Available This paper describes two phases of a community-directed intervention to address strongyloidiasis in the remote Aboriginal community of Woorabinda in central Queensland, Australia. The first phase provides the narrative of a community-driven ‘treat-and-test’ mass drug administration (MDA intervention that was co-designed by the Community Health Service and the community. The second phase is a description of the re-engagement of the community in order to disseminate the key factors for success in the previous MDA for Strongyloides stercoralis, as this information was not shared or captured in the first phase. During the first phase in 2004, there was a high prevalence of strongyloidiasis (12% faecal examination, 30% serology; n = 944 community members tested that resulted in increased morbidity and at least one death in the community. Between 2004–2005, the community worked in partnership with the Community Health Service to implement a S. stercoralis control program, where all of the residents were treated with oral ivermectin, and repeat doses were given for those with positive S. stercoralis serology. The community also developed their own health promotion campaign using locally-made resources targeting relevant environmental health problems and concerns. Ninety-two percent of the community residents participated in the program, and the prevalence of strongyloidiasis at the time of the ‘treat-and-test’ intervention was 16.6% [95% confidence interval 14.2–19.3]. The cure rate after two doses of ivermectin was 79.8%, based on pre-serology and post-serology tests. The purpose of this paper is to highlight the importance of local Aboriginal leadership and governance and a high level of community involvement in this successful mass drug administration program to address S. stercoralis. The commitment required of these leaders was demanding, and involved intense work over a period of several months. Apart from controlling strongyloidiasis

  17. 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.

  18. Use of direct washing of chemical dispense nozzle for defect control

    Science.gov (United States)

    Linnane, Michael; Mack, George; Longstaff, Christopher; Winter, Thomas

    2006-03-01

    Demands for continued defect reduction in 300mm IC manufacturing are driving process engineers to examine all aspects of the chemical apply process for improvement. Historically, the defect contribution from photoresist apply nozzles has been minimized through a carefully controlled process of "dummy dispenses" to keep the photoresist in the tip "fresh" and remove any solidified material, a preventive maintenance regime involving periodic cleaning or replacing of the nozzles, and reliance on a pool of solvent within the nozzle storage block to keep the photoresist from solidifying at the nozzle tip. The industry standard has worked well for the most part but has limitations in terms of cost effectiveness and absolute defect elimination. In this study, we investigate the direct washing of the chemical apply nozzle to reduce defects seen on the coated wafer. Data is presented on how the direct washing of the chemical dispense nozzle can be used to reduce coating related defects, reduce material costs from the reduction of "dummy dispense", and can reduce equipment downtime related to nozzle cleaning or replacement.

  19. 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.

  20. 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.

  1. Exploring direct 3D interaction for full horizontal parallax light field displays using leap motion controller.

    Science.gov (United States)

    Adhikarla, Vamsi Kiran; Sodnik, Jaka; Szolgay, Peter; Jakus, Grega

    2015-04-14

    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.

  2. 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

  3. Directional tip control technique for optimal stent graft alignment in angulated proximal aortic landing zones

    Directory of Open Access Journals (Sweden)

    Toshio Takayama, MD, PhD

    2017-06-01

    Full Text Available Angulated anatomy in the aorta, such as tortuous infrarenal aortic necks or steep aortic arches, is a significant challenge for endovascular aortic repair because it often causes inadequate sealing and fixation, which may lead to treatment failure. We have developed a technique using off-the-shelf equipment to precisely control the deployment of stent grafts in challenging landing zones. The key of this technique is to create a through-and-through wire between two access sites and to use a guiding device over the wire. This technique is best used with stent grafts without nose cones. We present an endovascular aneurysm repair case and a thoracic endovascular aortic repair case with challenging proximal landing zones treated by this technique. In both cases, technical success was attained, and follow-up imaging demonstrated well-aligned stent grafts. Our directional tip control technique is easy and effective. It can be a good technical solution for endovascular aortic treatment in angulated anatomy.

  4. Current control for magnetized plasma in direct-current plasma-immersion ion implantation

    International Nuclear Information System (INIS)

    Tang Deli; Chu, Paul K.

    2003-01-01

    A method to control the ion current in direct-current plasma-immersion ion implantation (PIII) is reported for low-pressure magnetized inductively coupled plasma. The ion current can be conveniently adjusted by applying bias voltage to the conducting grid that separates plasma formation and implantation (ion acceleration) zones without the need to alter the rf input power, gas flux, or other operating conditions. The ion current that diminishes with an increase in grid bias in magnetized plasmas can be varied from 48 to 1 mA by increasing the grid voltage from 0 to 70 V at -50 kV sample bias and 0.5 mTorr hydrogen pressure. High implantation voltage and monoenergetic immersion implantation can now be achieved by controlling the ion current without varying the macroscopic plasma parameters. The experimental results and interpretation of the effects are presented in this letter. This technique is very attractive for PIII of planar samples that require on-the-fly adjustment of the implantation current at high implantation voltage but low substrate temperature. In some applications such as hydrogen PIII-ion cut, it may obviate the need for complicated sample cooling devices that must work at high voltage

  5. Direct lexical control of eye movements in reading: Evidence from a survival analysis of fixation durations

    Science.gov (United States)

    Reingold, Eyal M.; Reichle, Erik D.; Glaholt, Mackenzie G.; Sheridan, Heather

    2013-01-01

    Participants’ eye movements were monitored in an experiment that manipulated the frequency of target words (high vs. low) as well as their availability for parafoveal processing during fixations on the pre-target word (valid vs. invalid preview). The influence of the word-frequency by preview validity manipulation on the distributions of first fixation duration was examined by using ex-Gaussian fitting as well as a novel survival analysis technique which provided precise estimates of the timing of the first discernible influence of word frequency on first fixation duration. Using this technique, we found a significant influence of word frequency on fixation duration in normal reading (valid preview) as early as 145 ms from the start of fixation. We also demonstrated an equally rapid non-lexical influence on first fixation duration as a function of initial landing position (location) on target words. The time-course of frequency effects, but not location effects was strongly influenced by preview validity, demonstrating the crucial role of parafoveal processing in enabling direct lexical control of reading fixation times. Implications for models of eye-movement control are discussed. PMID:22542804

  6. Design, fabrication, and application of a directional thermal processing system for controlled devitrification of metallic glasses

    Science.gov (United States)

    Meyer, Megan Anne Lamb

    The potential of using metallic glass as a pathway to obtaining novel morphologies and metastable phases has been garnering attention since their discovery. Several rapid solidification techniques; such as gas atomization, melt spinning, laser melting, and splat quenching produce amorphous alloys. A directional thermal processing system (DTPS) was designed, fabricated and characterized for the use of zone processing or gradient-zone processing of materials. Melt-spun CuZr metallic glass alloy was subjected to the DTPS and the relaxation and crystallization responses of the metallic glass were characterized. A range of processing parameters were developed and analyzed that would allow for devitrification to occur. The relaxation and crystallization responses were compared with traditional heat treatment methods of metallic glasses. The new processing method accessed equilibrium and non-equilibrium phases of the alloy and the structures were found to be controllable and sensitive to processing conditions. Crystallized fraction, crystallization onset temperature, and structural relaxation were controlled through adjusting the processing conditions, such as the hot zone temperature and sample velocity. Reaction rates computed from isothermal (TTT) transformation data were not found to be reliable, suggesting that the reaction kinetics are not additive. This new processing method allows for future studying of the thermal history effects of metallic glasses.

  7. Hes1 Directly Controls Cell Proliferation through the Transcriptional Repression of p27Kip1

    Science.gov (United States)

    Murata, Kaoru; Hattori, Masakazu; Hirai, Norihito; Shinozuka, Yoriko; Hirata, Hiromi; Kageyama, Ryoichiro; Sakai, Toshiyuki; Minato, Nagahiro

    2005-01-01

    A transcriptional regulator, Hes1, plays crucial roles in the control of differentiation and proliferation of neuronal, endocrine, and T-lymphocyte progenitors during development. Mechanisms for the regulation of cell proliferation by Hes1, however, remain to be verified. In embryonic carcinoma cells, endogenous Hes1 expression was repressed by retinoic acid in concord with enhanced p27Kip1 expression and cell cycle arrest. Conversely, conditional expression of a moderate but not maximal level of Hes1 in HeLa cells by a tetracycline-inducible system resulted in reduced p27Kip1 expression, which was attributed to decreased basal transcript rather than enhanced proteasomal degradation, with concomitant increases in the growth rate and saturation density. Hes1 induction repressed the promoter activity of a 5′ flanking basal enhancer region of p27Kip1 gene in a manner dependent on Hes1 expression levels, and this was mediated by its binding to class C sites in the promoter region. Finally, hypoplastic fetal thymi, as well as livers and brains of Hes1-deficient mice, showed significantly increased p27Kip1 transcripts compared with those of control littermates. These results have suggested that Hes1 directly contributes to the promotion of progenitor cell proliferation through transcriptional repression of a cyclin-dependent kinase inhibitor, p27Kip1. PMID:15870295

  8. 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.

  9. 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)

  10. 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

    of retinopathy in type 1 diabetes. METHODS: Two randomised, double-blind, parallel-design, placebo-controlled trials were done in 309 centres worldwide. Participants with normotensive, normoalbuminuric type 1 diabetes without retinopathy were recruited to the DIRECT-Prevent 1 trial and those with existing...... retinopathy were recruited to DIRECT-Protect 1, and were assigned to candesartan 16 mg once a day or matching placebo. After 1 month, the dose was doubled to 32 mg. Investigators and participants were unaware of the treatment allocation status. The primary endpoints were incidence and progression......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...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  12. Transcranial direct current stimulation versus user training on improving online myoelectric control for amputees

    Science.gov (United States)

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

    2017-08-01

    Objective. Transcranial direct current stimulation (tDCS) and user training (UT) are two types of methods to improve myoelectric control performance for amputees. In this study, we compared the independent effect between tDCS and UT, and investigated the combined effect of tDCS and UT. Approach. An online paradigm of simultaneous and proportional control (SPC) based on electromyography (EMG) was adopted. The proposed experiments were conducted on six naïve unilateral trans-radial amputees. The subjects each received three types of 20 min interventions: active tDCS with motor training (tDCS  +  UT), active tDCS with quiet sitting (tDCS), and sham tDCS with motor training (UT). The interventions were applied at one week intervals in a randomized order. The subjects performed online control of a feedback arrow with two degrees of freedom (DoFs) to accomplish target reaching motor tasks in pre-sessions and post-sessions. We compared the performance, measured by completion rate, completion time, and efficiency coefficient, between pre-sessions and post-sessions. Main results. The results showed that the intervention tDCS  +  UT and tDCS significantly improved the online SPC performance (i.e. improved the completion rate; reduced the completion time; and improved the efficiency coefficient), while intervention UT did not significantly change the performance. The results also showed that the online SPC performance after intervention tDCS  +  UT and tDCS was not significantly different, but both were significantly better than that after intervention UT. Significance. tDCS could be an effective intervention to improve the online SPC performance in a short time.

  13. Laser induced plasma methodology for ignition control in direct injection sprays

    International Nuclear Information System (INIS)

    Pastor, José V.; García-Oliver, José M.; García, Antonio; Pinotti, Mattia

    2016-01-01

    Highlights: • Laser Induced Plasma Ignition system is designed and applied to a Diesel Spray. • A method for quantification of the system effectiveness and reliability is proposed. • The ignition system is optimized in atmospheric and engine-like conditions. • Higher system effectiveness is reached with higher ambient density. • The system is able to stabilize Diesel combustion compared to auto-ignition cases. - Abstract: New combustion modes for internal combustion engines represent one of the main fields of investigation for emissions control in transportation Industry. However, the implementation of lean fuel mixture condition and low temperature combustion in real engines is limited by different unsolved practical issues. To achieve an appropriate combustion phasing and cycle-to-cycle control of the process, the laser plasma ignition system arises as a valid alternative to the traditional electrical spark ignition system. This paper proposes a methodology to set-up and optimize a laser induced plasma ignition system that allows ensuring reliability through the quantification of the system effectiveness in the plasma generation and positional stability, in order to reach optimal ignition performance. For this purpose, experimental tests have been carried out in an optical test rig. At first the system has been optimized in an atmospheric environment, based on the statistical analysis of the plasma records taken with a high speed camera to evaluate the induction effectiveness and consequently regulate and control the system settings. The same optimization method has then been applied under engine-like conditions, analyzing the effect of thermodynamic ambient conditions on the plasma induction success and repeatability, which have shown to depend mainly on ambient density. Once optimized for selected engine conditions, the laser plasma induction system has been used to ignite a direct injection Diesel spray, and to compare the evolution of combustion

  14. Microstructural control during direct laser deposition of a β-titanium alloy

    International Nuclear Information System (INIS)

    Qiu, Chunlei; Ravi, G.A.; Attallah, Moataz M.

    2015-01-01

    Graphical abstract: Microstructural development of Ti5553 during Direct Laser Deposition (DLD). - Highlights: • Good structural and geometrical integrity could be achieved by process design. • Build height increases with decreased scanning speed and increased powder flow rate. • Keeping Z increment close to actual layer thickness is crucial for consistent building. • The laser deposited Ti5553 are dominated by mixed columnar and equiaxed grains. • In situ dwelling and annealing promote α precipitation which improves microhardness. - Abstract: A concern associated with Direct Laser Deposition (DLD) is the difficulty in controlling microstructure due to rapid cooling rates after deposition, particularly in beta-Ti alloys. In these alloys, the beta-phase is likely to exist following DLD, instead of the desirable duplex alpha + beta microstructure that gives a good balance of properties. Thus, in this work, a parametric study was performed to assess the role of DLD parameters on porosity, build geometry, and microstructure in a beta-Ti alloy, Ti–5Al–5Mo–5V–3Cr (Ti5553). The builds were examined using optical microscopy, scanning electron microscopy, and X-ray diffraction. Microhardness measurements were performed to assess the degree of re-precipitation of alpha-phase following an in situ dwelling and laser annealing procedure. The study identified several processing conditions that enable deposition of samples with the desired geometry and low porosity level. The microstructure was dominated by beta-phase, except for the region near the substrate where a limited amount of alpha-precipitates was present due to reheating effect. Although the microstructure was a mixture of equiaxed and columnar beta-grains alongside infrequent fine alpha-precipitates, the builds showed fairly uniform microhardness in different regions. In situ dwelling and annealing did not cause an obvious change in porosity, but did promote the formation of alpha-precipitates

  15. Safety and feasibility of transcranial direct current stimulation in pediatric hemiparesis: randomized controlled preliminary study.

    Science.gov (United States)

    Gillick, Bernadette T; Feyma, Tim; Menk, Jeremiah; Usset, Michelle; Vaith, Amy; Wood, Teddi Jean; Worthington, Rebecca; Krach, Linda E

    2015-03-01

    Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation that has shown improved adult stroke outcomes. Applying tDCS in children with congenital hemiparesis has not yet been explored. The primary objective of this study was to explore the safety and feasibility of single-session tDCS through an adverse events profile and symptom assessment within a double-blind, randomized placebo-controlled preliminary study in children with congenital hemiparesis. A secondary objective was to assess the stability of hand and cognitive function. A double-blind, randomized placebo-controlled pretest/posttest/follow-up study was conducted. The study was conducted in a university pediatric research laboratory. Thirteen children, ages 7 to 18 years, with congenital hemiparesis participated. Adverse events/safety assessment and hand function were measured. Participants were randomly assigned to either an intervention group or a control group, with safety and functional assessments at pretest, at posttest on the same day, and at a 1-week follow-up session. An intervention of 10 minutes of 0.7 mA tDCS was applied to bilateral primary motor cortices. The tDCS intervention was considered safe if there was no individual decline of 25% or group decline of 2 standard deviations for motor evoked potentials (MEPs) and behavioral data and no report of adverse events. No major adverse events were found, including no seizures. Two participants did not complete the study due to lack of MEP and discomfort. For the 11 participants who completed the study, group differences in MEPs and behavioral data did not exceed 2 standard deviations in those who received the tDCS (n=5) and those in the control group (n=6). The study was completed without the need for stopping per medical monitor and biostatisticial analysis. A limitation of the study was the small sample size, with data available for 11 participants. Based on the results of this study, tDCS appears to be safe

  16. 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.

  17. 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.

  18. 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.

  19. Rho kinase activity controls directional cell movements during primitive streak formation in the rabbit embryo.

    Science.gov (United States)

    Stankova, Viktoria; Tsikolia, Nikoloz; Viebahn, Christoph

    2015-01-01

    During animal gastrulation, the specification of the embryonic axes is accompanied by epithelio-mesenchymal transition (EMT), the first major change in cell shape after fertilization. EMT takes place in disparate topographical arrangements, such as the circular blastopore of amphibians, the straight primitive streak of birds and mammals or in intermediate gastrulation forms of other amniotes such as reptiles. Planar cell movements are prime candidates to arrange specific modes of gastrulation but there is no consensus view on their role in different vertebrate classes. Here, we test the impact of interfering with Rho kinase-mediated cell movements on gastrulation topography in blastocysts of the rabbit, which has a flat embryonic disc typical for most mammals. Time-lapse video microscopy, electron microscopy, gene expression and morphometric analyses of the effect of inhibiting ROCK activity showed - besides normal specification of the organizer region - a dose-dependent disruption of primitive streak formation; this disruption resulted in circular, arc-shaped or intermediate forms, reminiscent of those found in amphibians, fishes and reptiles. Our results reveal a crucial role of ROCK-controlled directional cell movements during rabbit primitive streak formation and highlight the possibility that temporal and spatial modulation of cell movements were instrumental for the evolution of gastrulation forms. © 2015. Published by The Company of Biologists Ltd.

  20. Implications of the second law for future directions in controlled fusion research

    International Nuclear Information System (INIS)

    Roth, J.R.; Miley, G.H.

    1980-01-01

    Many existing energy related technologies have developed under the influence of social, economic, or state of the art constraints, and they cannot be viewed as optimum systems according to the second law of thermodynamics. Controlled fusion research presents an opportunity to optimize a nascent technology with respect to second law considerations in order to develop a practical energy source. In its present state of development, fusion research offers several independent approaches that may result in a net power producing fusion reactor. This paper discusses how second law considerations might be used to narrow the range of choices that must be made among various fusion fuel cycles. From a second law point of view, the most desirable fusion reactors are those for which the energy of charged particles can be converted directly into d.c. electrical power, while still allowing the energy that could be recovered by an efficient high-temperature 'blanket' to be transported largely by radiation. Fusion research in all major industrialized countries is developing the deuterium-tritium (D-T) fuel cycle for first-generation fusion power plants. It will be shown that other fuel cycles have significant advantages over the D-T fuel cycle according to second law principles. (author)

  1. Direct infusion mass spectrometry metabolomics dataset: a benchmark for data processing and quality control

    Science.gov (United States)

    Kirwan, Jennifer A; Weber, Ralf J M; Broadhurst, David I; Viant, Mark R

    2014-01-01

    Direct-infusion mass spectrometry (DIMS) metabolomics is an important approach for characterising molecular responses of organisms to disease, drugs and the environment. Increasingly large-scale metabolomics studies are being conducted, necessitating improvements in both bioanalytical and computational workflows to maintain data quality. This dataset represents a systematic evaluation of the reproducibility of a multi-batch DIMS metabolomics study of cardiac tissue extracts. It comprises of twenty biological samples (cow vs. sheep) that were analysed repeatedly, in 8 batches across 7 days, together with a concurrent set of quality control (QC) samples. Data are presented from each step of the workflow and are available in MetaboLights. The strength of the dataset is that intra- and inter-batch variation can be corrected using QC spectra and the quality of this correction assessed independently using the repeatedly-measured biological samples. Originally designed to test the efficacy of a batch-correction algorithm, it will enable others to evaluate novel data processing algorithms. Furthermore, this dataset serves as a benchmark for DIMS metabolomics, derived using best-practice workflows and rigorous quality assessment. PMID:25977770

  2. How Structure-Directing Agents Control Nanocrystal Shape: Polyvinylpyrrolidone-Mediated Growth of Ag Nanocubes.

    Science.gov (United States)

    Qi, Xin; Balankura, Tonnam; Zhou, Ya; Fichthorn, Kristen A

    2015-11-11

    The importance of structure-directing agents (SDAs) in the shape-selective synthesis of colloidal nanostructures has been well documented. However, the mechanisms by which SDAs actuate shape control are poorly understood. In the polyvinylpyrrolidone (PVP)-mediated growth of {100}-faceted Ag nanocrystals, this capability has been attributed to preferential binding of PVP to Ag(100). We use molecular dynamics simulations to probe the mechanisms by which Ag atoms add to Ag(100) and Ag(111) in ethylene glycol solution with PVP. We find that PVP induces kinetic Ag nanocrystal shapes by regulating the relative Ag fluxes to these facets. Stronger PVP binding to Ag(100) leads to a larger Ag flux to Ag(111) and cubic nanostructures through two mechanisms: enhanced Ag trapping by more extended PVP films on Ag(111) and a reduced free-energy barrier for Ag to cross lower-density films on Ag(111). These flux-regulating capabilities depend on PVP concentration and chain length, consistent with experiment.

  3. A directed-overflow and damage-control N-glycosidase in riboflavin biosynthesis

    Science.gov (United States)

    Frelin, Océane; Huang, Lili; Hasnain, Ghulam; Jeffryes, James G.; Ziemak, Michael J.; Rocca, James R.; Wang, Bing; Rice, Jennifer; Roje, Sanja; Yurgel, Svetlana N.; Gregory, Jesse F.; Edison, Arthur S.; Henry, Christopher S.; deCrécy-Lagard, Valérie; Hanson, Andrew D.

    2015-01-01

    Plants and bacteria synthesize the essential human micronutrient riboflavin (vitamin B2) via the same multistep pathway. The early intermediates of this pathway are notoriously reactive, and may be overproduced in vivo because riboflavin biosynthesis enzymes lack feedback controls. Here we demonstrate disposal of riboflavin intermediates by COG3236 (DUF1768), a protein of previously unknown function that is fused to two different riboflavin pathway enzymes in plants and bacteria (RIBR and RibA, respectively). We present cheminformatic, biochemical, genetic, and genomic evidence to show that: (i) plant and bacterial COG3236 proteins cleave the N-glycosidic bond of the first two intermediates of riboflavin biosynthesis, yielding relatively innocuous products; (ii) certain COG3236 proteins are in a multienzyme riboflavin biosynthesis complex that gives them privileged access to riboflavin intermediates; and (iii) COG3236 action in Arabidopsis thaliana and Escherichia coli helps maintain flavin levels. COG3236 proteins thus illustrate two emerging principles in chemical biology: directed overflow metabolism, in which excess flux is diverted out of a pathway, and the pre-emption of damage from reactive metabolites. PMID:25431972

  4. Direct-to-consumer marketing of psychological treatments: A randomized controlled trial.

    Science.gov (United States)

    Gallo, Kaitlin P; Comer, Jonathan S; Barlow, David H; Clarke, Roberta N; Antony, Martin M

    2015-10-01

    Although direct-to-consumer (DTC) marketing of pharmacologic interventions is effective and common, similar approaches have yet to be evaluated in the promotion of psychological treatments (PTs). This is the first randomized controlled trial evaluating the potential of DTC marketing of PTs. Participants (N = 344; 75.0% female, mean age = 18.6 years, 48.5% non-Hispanic White) were randomly assigned to consume one of four extended commercial campaigns embedded within unrelated programming across 3 weeks. The four campaign conditions were a PT campaign, a PT informing about medication side effects campaign, a medication campaign, and a neutral campaign. Attitudes about and intention to seek psychological treatment were assessed prior to campaign exposure (T1), 1 week following the final week of campaign exposure (T2), and at a 3-month follow-up evaluation (T3). The percentage of participants who newly intended psychological treatment at T2 or T3 differed by condition, with those assigned to the PT campaign slightly more likely to have intended to receive psychological treatment at T2 or T3 than those in other conditions. Baseline reports of emotional symptoms moderated the effect of condition on attitudes toward PT and perceived likelihood of seeking treatment in the future. Findings support the preliminary utility of DTC marketing of psychological treatments. Increasing consumer knowledge of PTs may be a worthwhile complement to current dissemination and implementation efforts aimed at promoting the uptake of PTs in mental health care. (c) 2015 APA, all rights reserved).

  5. 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.

  6. A theoretical study on directivity control of multiple-loudspeaker system with a quadrupole radiation pattern in low frequency range

    Science.gov (United States)

    Irwansyah, Kuse, Naoyuki; Usagawa, Tsuyoshi

    2017-08-01

    Directivity pattern of an ordinary loudspeaker becomes more directive at higher frequencies. However, because a single loudspeaker tends to radiate uniformly in all directions at low frequencies, reverberation from surrounding building walls may affect speech intelligibility when installing a multiple-loudspeaker system at crossroads. As an alternative, a sharply directive sound source is recommended to be used, but in many cases the directivity of an ordinary loudspeaker is less sharp at lower frequencies. Therefore, in order to overcome such a limitation, this paper discusses the possibility of using four loudspeakers under active control to realize a quadrupole radiation pattern in low frequency range. In this study, the radiation pattern of a primary loudspeaker and three secondary loudspeakers has been modelled. By placing the loudspeakers close together in the direction of 0°, 90°, 180°, and 270°, it was theoretically demonstrated that a quadrupole radiation pattern can be shaped in the target frequency range up to 600 Hz by simply controlling the directivity in three of four directions which are 45°, 135°, 225°, and 315°. Although, the radiation pattern model is far from realistic configurations and conditions, it is possible to realize a quadrupole radiation pattern in the low frequency range.

  7. 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...... that total on-chip power is reduced for unidirectional IO Standard based Video PHY controller compared to bidirectional IO Standard based Video PHY controller. The most significant achievement of this work is that it is concluded that unidirectional IO Standard based Video PHY controller consume least...... standby power compared to bidirectional IO Standard based Video PHY controller. It is defined that for 6 GHz operated frequency Video PHY controller, the 32% total on-chip power is reduced using unidirectional IO Standard based Video PHY controller is less compared to bidirectional IO Standard based Video...

  8. Use of alternating and pulsed direct current electrified fields for zebra mussel control

    Science.gov (United States)

    Luoma, James A.; Dean, Jan C.; Severson, Todd J.; Wise, Jeremy K.; Barbour, Matthew

    2017-01-01

    Alternatives to chemicals for controlling dreissenid mussels are desirable for environmental compatibility, but few alternatives exist. Previous studies have evaluated the use of electrified fields for stunning and/or killing planktonic life stages of dreissenid mussels, however, the available literature on the use of electrified fields to control adult dreissenid mussels is limited. We evaluated the effects of sinusoidal alternating current (AC) and 20% duty cycle square-wave pulsed direct current (PDC) exposure on the survival of adult zebra mussels at water temperatures of 10, 15, and 22 °C. Peak voltage gradients of ~ 17 and 30 Vp/cm in the AC and PDC exposures, respectively, were continuously applied for 24, 48, or 72 h. Peak power densities ranged from 77,999 to 107,199 µW/cm3 in the AC exposures and 245,320 to 313,945 µW/cm3 in the PDC exposures. The peak dose ranged from 6,739 to 27,298 Joules/cm3 and 21,306 to 80,941 Joules/cm3 in the AC and PDC exposures, respectively. The applied power ranged from 16.6 to 68.9 kWh in the AC exposures and from 22.2 to 86.4 kWh in the PDC exposures. Mortality ranged from 2.7 to 92.7% in the AC exposed groups and from 24.0 to 98.7% in PDC exposed groups. Mortality increased with corresponding increases in water temperature and exposure duration, and we observed more zebra mussel mortality in the PDC exposures. Exposures conducted with AC required less of a peak dose (Joules/cm3) but more applied power (kWh) to achieve the same level of adult zebra mussel mortality as corresponding PDC exposures. The results demonstrate that 20% duty cycle square-wave PDC requires less energy than sinusoidal AC to inducing the same level of adult zebra mussel mortality.

  9. 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.

  10. Distributed Adaptive Finite-Time Approach for Formation-Containment Control of Networked Nonlinear Systems Under Directed Topology.

    Science.gov (United States)

    Wang, Yujuan; Song, Yongduan; Ren, Wei

    2017-07-06

    This paper presents a distributed adaptive finite-time control solution to the formation-containment problem for multiple networked systems with uncertain nonlinear dynamics and directed communication constraints. By integrating the special topology feature of the new constructed symmetrical matrix, the technical difficulty in finite-time formation-containment control arising from the asymmetrical Laplacian matrix under single-way directed communication is circumvented. Based upon fractional power feedback of the local error, an adaptive distributed control scheme is established to drive the leaders into the prespecified formation configuration in finite time. Meanwhile, a distributed adaptive control scheme, independent of the unavailable inputs of the leaders, is designed to keep the followers within a bounded distance from the moving leaders and then to make the followers enter the convex hull shaped by the formation of the leaders in finite time. The effectiveness of the proposed control scheme is confirmed by the simulation.

  11. The ribosome structure controls and directs mRNA entry, translocation and exit dynamics

    International Nuclear Information System (INIS)

    Kurkcuoglu, Ozge; Doruker, Pemra; Jernigan, Robert L; Sen, Taner Z; Kloczkowski, Andrzej

    2008-01-01

    The protein-synthesizing ribosome undergoes large motions to effect the translocation of tRNAs and mRNA; here, the domain motions of this system are explored with a coarse-grained elastic network model using normal mode analysis. Crystal structures are used to construct various model systems of the 70S complex with/without tRNA, elongation factor Tu and the ribosomal proteins. Computed motions reveal the well-known ratchet-like rotational motion of the large subunits, as well as the head rotation of the small subunit and the high flexibility of the L1 and L7/L12 stalks, even in the absence of ribosomal proteins. This result indicates that these experimentally observed motions during translocation are inherently controlled by the ribosomal shape and only partially dependent upon GTP hydrolysis. Normal mode analysis further reveals the mobility of A- and P-tRNAs to increase in the absence of the E-tRNA. In addition, the dynamics of the E-tRNA is affected by the absence of the ribosomal protein L1. The mRNA in the entrance tunnel interacts directly with helicase proteins S3 and S4, which constrain the mRNA in a clamp-like fashion, as well as with protein S5, which likely orients the mRNA to ensure correct translation. The ribosomal proteins S7, S11 and S18 may also be involved in assuring translation fidelity by constraining the mRNA at the exit site of the channel. The mRNA also interacts with the 16S 3' end forming the Shine–Dalgarno complex at the initiation step; the 3' end may act as a 'hook' to reel in the mRNA to facilitate its exit

  12. Diagnostic Assessment of the Difficulty Using Direct Policy Search in Many-Objective Reservoir Control

    Science.gov (United States)

    Zatarain-Salazar, J.; Reed, P. M.; Herman, J. D.; Giuliani, M.; Castelletti, A.

    2014-12-01

    Globally reservoir operations provide fundamental services to water supply, energy generation, recreation, and ecosystems. The pressures of expanding populations, climate change, and increased energy demands are motivating a significant investment in re-operationalizing existing reservoirs or defining operations for new reservoirs. Recent work has highlighted the potential benefits of exploiting recent advances in many-objective optimization and direct policy search (DPS) to aid in addressing these systems' multi-sector demand tradeoffs. This study contributes to a comprehensive diagnostic assessment of multi-objective evolutionary optimization algorithms (MOEAs) efficiency, effectiveness, reliability, and controllability when supporting DPS for the Conowingo dam in the Lower Susquehanna River Basin. The Lower Susquehanna River is an interstate water body that has been subject to intensive water management efforts due to the system's competing demands from urban water supply, atomic power plant cooling, hydropower production, and federally regulated environmental flows. Seven benchmark and state-of-the-art MOEAs are tested on deterministic and stochastic instances of the Susquehanna test case. In the deterministic formulation, the operating objectives are evaluated over the historical realization of the hydroclimatic variables (i.e., inflows and evaporation rates). In the stochastic formulation, the same objectives are instead evaluated over an ensemble of stochastic inflows and evaporation rates realizations. The algorithms are evaluated in their ability to support DPS in discovering reservoir operations that compose the tradeoffs for six multi-sector performance objectives with thirty-two decision variables. Our diagnostic results highlight that many-objective DPS is very challenging for modern MOEAs and that epsilon dominance is critical for attaining high levels of performance. Epsilon dominance algorithms epsilon-MOEA, epsilon-NSGAII and the auto adaptive Borg

  13. 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 (<0.7 mg/L). At dosages ≥4.6 mg L(-1) h(-1), an O3/H2O2 mass ratio of 3.4-3.8, and initial COD <20 mg/L, a simple first order decay was indicated for both single-passed treated wastewater and recycled mineral 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Orexins control intestinal glucose transport by distinct neuronal, endocrine, and direct epithelial pathways.

    Science.gov (United States)

    Ducroc, Robert; Voisin, Thierry; El Firar, Aadil; Laburthe, Marc

    2007-10-01

    Orexins are neuropeptides involved in energy homeostasis. We investigated the effect of orexin A (OxA) and orexin B (OxB) on intestinal glucose transport in the rat. Injection of orexins led to a decrease in the blood glucose level in oral glucose tolerance tests (OGTTs). Effects of orexins on glucose entry were analyzed in Ussing chambers using the Na(+)-dependent increase in short-circuit current (Isc) to quantify jejunal glucose transport. The rapid and marked increase in Isc induced by luminal glucose was inhibited by 10 nmol/l OxA or OxB (53 and 59%, respectively). Response curves to OxA and OxB were not significantly different with half-maximal inhibitory concentrations at 0.9 and 0.4 nmol/l, respectively. On the one hand, OxA-induced inhibition of Isc was reduced by the neuronal blocker tetrodotoxin (TTX) and by a cholecystokinin (CCK) 2R antagonist, indicating involvement of neuronal and endocrine CCK-releasing cells. The OX(1)R antagonist SB334867 had no effect on OxA-induced inhibition, which is likely to occur via a neuronal and/or endocrine OX(2)R. On the other hand, SB334867 induced a significant right shift of the concentration-effect curve for OxB. This OxB-preferring OX(1)R pathway was not sensitive to TTX or to CCKR antagonists, suggesting that OxB may act directly on enterocytic OX(1)R. These distinct effects of OxA and OxB are consistent with the expression of OX(1)R and OX(2)R mRNA in the epithelial and nonepithelial tissues, respectively. Our data delineate a new function for orexins as inhibitors of intestinal glucose absorption and provide a new basis for orexin-induced short-term control of energy homeostasis.

  15. Simple Moving Voltage Average Incremental Conductance MPPT Technique with Direct Control Method under Nonuniform Solar Irradiance Conditions

    Directory of Open Access Journals (Sweden)

    Amjad Ali

    2015-01-01

    Full Text Available A new simple moving voltage average (SMVA technique with fixed step direct control incremental conductance method is introduced to reduce solar photovoltaic voltage (VPV oscillation under nonuniform solar irradiation conditions. To evaluate and validate the performance of the proposed SMVA method in comparison with the conventional fixed step direct control incremental conductance method under extreme conditions, different scenarios were simulated. Simulation results show that in most cases SMVA gives better results with more stability as compared to traditional fixed step direct control INC with faster tracking system along with reduction in sustained oscillations and possesses fast steady state response and robustness. The steady state oscillations are almost eliminated because of extremely small dP/dV around maximum power (MP, which verify that the proposed method is suitable for standalone PV system under extreme weather conditions not only in terms of bus voltage stability but also in overall system efficiency.

  16. 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.

  17. Efficient direct yaw moment control: tyre slip power loss minimisation for four-independent wheel drive vehicle

    Science.gov (United States)

    Kobayashi, Takao; Katsuyama, Etsuo; Sugiura, Hideki; Ono, Eiichi; Yamamoto, Masaki

    2018-05-01

    This paper proposes an efficient direct yaw moment control (DYC) capable of minimising tyre slip power loss on contact patches for a four-independent wheel drive vehicle. Simulations identified a significant power loss reduction with a direct yaw moment due to a change in steer characteristics during acceleration or deceleration while turning. Simultaneously, the vehicle motion can be stabilised. As a result, the proposed control method can ensure compatibility between vehicle dynamics performance and energy efficiency. This paper also describes the results of a full-vehicle simulation that was conducted to examine the effectiveness of the proposed DYC.

  18. Control of Canadian once-through direct cycle supercritical water-cooled reactors

    International Nuclear Information System (INIS)

    Sun, Peiwei; Wang, Baosheng; Zhang, Jianmin; Su, Guanghui

    2015-01-01

    Highlights: • Dynamic characteristics of Canadian SCWR are analyzed. • Hybrid feedforward and feedback control is adopted to deal with cross-coupling. • Gain scheduling control with smooth weight is applied to deal with nonlinearity. • It demonstrates through simulation that the control requirements are satisfied. - Abstract: Canadian supercritical water-cooled reactor (SCWR) can be modelled as a Multiple-input Multiple-output (MIMO) system. It has a high power-to-flow ratio, strong cross-coupling and high degree of nonlinearity in its dynamic characteristics. Among the outputs, the steam temperature is strongly affected by the reactor power and the most challenging to control. It is difficult to adopt a traditional control system design methodology to obtain a control system with satisfactory performance. In this paper, feedforward control is applied to reduce the effect on steam temperature from the reactor power. Single-input Single-output (SISO) feedback controllers are synthesized in the frequency domain. Using the feedforward controller, the steam temperature variation due to disturbances at the reactor power has been significantly suppressed. The control system can effectively maintain the overall system stability and regulate the plant around a specified operating condition. To deal with the nonlinearities, gain scheduling control strategy is adopted. Different sets of controllers combined by smooth weight functions are used for the plant at different load conditions. The proposed control strategies have been evaluated under various operating scenarios. Simulation results show that satisfactory performance can successfully achieved by the designed control system

  19. A study of direct-current surface discharge plasma for a Mach 3 supersonic flow control

    Science.gov (United States)

    Shin, Jichul

    A direct-current, non-equilibrium surface glow discharge plasma in the presence of a Mach 2.85 flow is studied experimentally for flow control applications. The discharge is generated with pin-like electrodes flush mounted on a ceramic plate with sustaining currents from 25 mA to 300 mA. In the presence of a supersonic flow, two distinct discharge modes - diffuse and constricted - are observed depending on the flow and discharge operating conditions. In cathode upstream location, both diffuse and constricted discharges are observed while in cathode downstream location, the discharge mostly exhibits either constricted mode or bistable mixed mode. The effect of the discharge on the flow ("plasma actuation'') is characterized by the appearance of a weak shock wave in the vicinity of the discharge. The shock is observed at low powers (˜10 W) for the diffuse discharge mode but is absent for the higher power (˜100 W) constricted mode. High speed laser schlieren imaging suggests that the diffuse mode plasma actuation is rapid as it occurs on a time scale that is less than 100 microsec. Rotational (gas) and vibrational temperatures within the discharge are estimated by emission spectral line fits of N 2 and N+2 rovibronic bands near 365-395 nm. The electronic temperatures are estimated by using the Boltzmann plot method for Fe(I) atomic lines. Rotational temperatures are found to be high (˜1500 K) in the absence of a flow but drop sharply (˜500 K) in the presence of a supersonic flow for both the diffuse and constricted discharge modes. The vibrational and electronic temperatures are measured to be about 3000 K and 1.25 eV (14500 K), respectively, and these temperatures are the same with and without flow. The gas (rotational) temperature spatial profiles above the cathode surface are found to be similar for the diffuse and constricted modes indicating that dilatational effects due to gas heating are similar. However, complete absence of flow actuation for the

  20. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Effect of illicit direct to consumer advertising on use of etanercept, mometasone, and tegaserod in Canada: controlled longitudinal study

    Science.gov (United States)

    Majumdar, Sumit R; Soumerai, Stephen B

    2008-01-01

    Objective To assess the impact of direct to consumer advertising of prescription drugs in the United States on Canadian prescribing rates for three heavily marketed drugs—etanercept, mometasone, and tegaserod. Design Controlled quasi-experimental study using interrupted time series analysis. Population Representative sample of 2700 Canadian pharmacies and prescription data from 50 US Medicaid programmes. Main outcome measures Differences in number of filled prescriptions per 10 000 population per month between English speaking and French speaking (control) Canadian provinces before and after the start of direct to consumer advertising in the United States. Results Spending on direct to consumer advertising for study drugs ranged from $194m to $314m (£104m-£169m; €131m-€212m) over the study period. Prescription rates for etanercept and mometasone did not increase in English speaking provinces relative to French speaking controls after the start of direct to consumer advertising. In contrast, tegaserod prescriptions increased 42% (0.56 prescriptions/10 000 residents, 95% confidence interval 0.37 to 0.76) in English speaking provinces immediately after the start of US direct to consumer advertising. Uncontrolled analysis of US Medicaid data showed a larger 56% increase in tegaserod prescriptions. However, this increase did not persist over time in either country, despite continued advertising. Conclusions Exposure to US direct to consumer advertising transiently influenced both Canadian and US prescribing rates for tegaserod, a drug later withdrawn owing to safety concerns. The impact of direct to consumer advertising on drug use seems to be highly variable and probably depends on the characteristics of the advertised drug, the level of exposure to direct to consumer advertising, and the cultural context. PMID:18765444

  2. Effect of illicit direct to consumer advertising on use of etanercept, mometasone, and tegaserod in Canada: controlled longitudinal study.

    Science.gov (United States)

    Law, Michael R; Majumdar, Sumit R; Soumerai, Stephen B

    2008-09-02

    To assess the impact of direct to consumer advertising of prescription drugs in the United States on Canadian prescribing rates for three heavily marketed drugs-etanercept, mometasone, and tegaserod. Controlled quasi-experimental study using interrupted time series analysis. Representative sample of 2700 Canadian pharmacies and prescription data from 50 US Medicaid programmes. Differences in number of filled prescriptions per 10,000 population per month between English speaking and French speaking (control) Canadian provinces before and after the start of direct to consumer advertising in the United States. Spending on direct to consumer advertising for study drugs ranged from $194m to $314m ( pound104m- pound169m; euro131m-euro212m) over the study period. Prescription rates for etanercept and mometasone did not increase in English speaking provinces relative to French speaking controls after the start of direct to consumer advertising. In contrast, tegaserod prescriptions increased 42% (0.56 prescriptions/10,000 residents, 95% confidence interval 0.37 to 0.76) in English speaking provinces immediately after the start of US direct to consumer advertising. Uncontrolled analysis of US Medicaid data showed a larger 56% increase in tegaserod prescriptions. However, this increase did not persist over time in either country, despite continued advertising. Exposure to US direct to consumer advertising transiently influenced both Canadian and US prescribing rates for tegaserod, a drug later withdrawn owing to safety concerns. The impact of direct to consumer advertising on drug use seems to be highly variable and probably depends on the characteristics of the advertised drug, the level of exposure to direct to consumer advertising, and the cultural context.

  3. Direct Speed Control of PMSM Drive Using SDRE and Convex Constrained Optimization

    Czech Academy of Sciences Publication Activity Database

    Šmídl, V.; Janouš, Š.; Adam, Lukáš; Peroutka, Z.

    2018-01-01

    Roč. 65, č. 1 (2018), s. 532-542 ISSN 1932-4529 Grant - others:GA MŠk(CZ) LO1607 Institutional support: RVO:67985556 Keywords : Velocity control * Optimization * Stators * Voltage control * Predictive control * Optimal control * Rotors Subject RIV: BD - Theory of Information Impact factor: 10.710, year: 2016 http://library.utia.cas.cz/separaty/2017/AS/smidl-0481225.pdf

  4. Micropump Fuel Mix Control for Novel Miniature Direct Methanol Fuel Cells, Phase I

    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...

  5. Advanced control of direct-driven PMSG generator in wind turbine system

    Directory of Open Access Journals (Sweden)

    Gajewski Piotr

    2016-12-01

    Full Text Available The paper presents the advanced control system of the wind energy conversion with a variable speed wind turbine. The considered system consists of a wind turbine with the permanent magnet synchronous generator (PMSG, machine side converter (MSC, grid side converter (GSC and control circuits. The mathematical models of a wind turbine system, the PMSG generator and converters have been described. The control algorithms of the converter systems based on the methods of vector control have been applied. In the advanced control system of the machine side converter the optimal MPPT control method has been used. Additionally the pitch control scheme is included in order to achieve the limitation of maximum power and to prevent mechanical damage of the wind turbine. In the control system of the grid side converter the control of active and reactive power has been applied with the application of Voltage Oriented Control (VOC. The performance of the considered wind energy system has been studied by digital simulation. The results of simulation studies confirmed the good effectiveness of the considered wind turbine system and very good performance of the proposed methods of vector control and control systems.

  6. A wind-tunnel investigation of parameters affecting helicopter directional control at low speeds in ground effect

    Science.gov (United States)

    Yeager, W. T., Jr.; Young, W. H., Jr.; Mantay, W. R.

    1974-01-01

    An investigation was conducted in the Langley full-scale tunnel to measure the performance of several helicopter tail-rotor/fin configurations with regard to directional control problems encountered at low speeds in ground effect. Tests were conducted at wind azimuths of 0 deg to 360 deg in increments of 30 deg and 60 deg and at wind speeds from 0 to 35 knots. The results indicate that at certain combinations of wind speed and wind azimuth, large increases in adverse fin force require correspondingly large increases in the tail-rotor thrust, collective pitch, and power required to maintain yaw trim. Changing the tail-rotor direction of rotation to top blade aft for either a pusher tail rotor (tail-rotor wake blowing away from fin) or a tractor tail rotor (tail-rotor wake blowing against fin) will alleviate this problem. For a pusher tail rotor at 180 deg wind azimuth, increases in the fin/tail-rotor gap were not found to have any significant influence on the overall vehicle directional control capability. Changing the tail rotor to a higher position was found to improve tail-rotor performance for a fin-off configuration at a wind azimuth of 180 deg. A V-tail configuration with a pusher tail rotor with top blade aft direction of rotation was found to be the best configuration with regard to overall directional control capability.

  7. Effects of gut-directed hypnotherapy on IBS in different clinical settings-results from two randomized, controlled trials.

    Science.gov (United States)

    Lindfors, Perjohan; Unge, Peter; Arvidsson, Patrik; Nyhlin, Henry; Björnsson, Einar; Abrahamsson, Hasse; Simrén, Magnus

    2012-02-01

    Gut-directed hypnotherapy has been found to be effective in irritable bowel syndrome (IBS). However, randomized, controlled studies are rare and few have been performed outside highly specialized research centers. The objective of this study was to study the effect of gut-directed hypnotherapy in IBS in different clinical settings outside the traditional research units. The study population included IBS patients refractory to standard management. In study 1, patients were randomized to receive gut-directed hypnotherapy (12 sessions, 1 h/week) in psychology private practices or supportive therapy, whereas patients were randomized to receive gut-directed hypnotherapy in a small county hospital or to serve as waiting list controls in study 2. Gastrointestinal symptom severity and quality of life were evaluated at baseline, at 3 months follow-up and after 1 year. We randomized 138 IBS patients refractory to standard management, 90 in study 1 and 48 in study 2. In both the studies, IBS-related symptoms were improved at 3 months in the gut-directed hypnotherapy groups (Phypnotherapy group than in the control group (Phypnotherapy is an effective treatment alternative for patients with refractory IBS, but the effectiveness is lower when the therapy is given outside the highly specialized research centers.

  8. Design and implementation of high performance direct power control of three-phase PWM rectifier, via fuzzy and PI controller for output voltage regulation

    International Nuclear Information System (INIS)

    Bouafia, Abdelouahab; Krim, Fateh; Gaubert, Jean-Paul

    2009-01-01

    This paper proposes direct power control (DPC) for three-phase PWM rectifiers using a new switching table, without line voltage sensors. The instantaneous active and reactive powers, directly controlled by selecting the optimum state of the converter, are used as the PWM control variables instead of the phase line currents being used. The main goal of the control system is to maintain the dc-bus voltage at the required level, while input currents drawn from the power supply should be sinusoidal and in phase with respective phase voltages to satisfy the unity power factor (UPF) operation. Conventional PI and a designed fuzzy logic-based controller, in the dc-bus voltage control loop, have been used to provide active power command. A dSPACE based experimental system was developed to verify the validity of the proposed DPC. The steady-state, and dynamic results illustrating the operation and performance of the proposed control scheme are presented. As a result, it was confirmed that the novel DPC is much better than the classical one. Line currents very close to sinusoidal waveforms (THD < 2%) and good regulation of dc-bus voltage are achieved using PI or fuzzy controller. Moreover, fuzzy logic controller gives excellent performance in transient state, a good rejection of impact load disturbance, and a good robustness

  9. Reconfigurable multivariable control law for commercial airplane using a direct digital output feedback design

    Science.gov (United States)

    Ostroff, A. J.; Hueschen, R. M.

    1984-01-01

    The ability of a pilot to reconfigure the control surfaces on an airplane after a failure, allowing the airplane to recover to a safe condition for landing, becomes more difficult with increasing airplane complexity. Techniques are needed to stabilize and control the airplane immediately after a failure, allowing the pilot time to make longer range decisions. This paper shows a design of a discrete multivariable control law using four controls for the longitudinal channel of a B-737. Single control element failures are allowed in three of the four controls. The four controls design and failure cases are analyzed by means of a digital airplane simulation, with regard to tracking capability and ability to overcome severe windshear and turbulence during the aproach and landing phase of flight.

  10. A novel integrated approach for path following and directional stability control of road vehicles after a tire blow-out

    Science.gov (United States)

    Wang, Fei; Chen, Hong; Guo, Konghui; Cao, Dongpu

    2017-09-01

    The path following and directional stability are two crucial problems when a road vehicle experiences a tire blow-out or sudden tire failure. Considering the requirement of rapid road vehicle motion control during a tire blow-out, this article proposes a novel linearized decoupling control procedure with three design steps for a class of second order multi-input-multi-output non-affine system. The evaluating indicators for controller performance are presented and a performance related control parameter distribution map is obtained based on the stochastic algorithm which is an innovation for non-blind parameter adjustment in engineering implementation. The analysis on the robustness of the proposed integrated controller is also performed. The simulation studies for a range of driving conditions are conducted, to demonstrate the effectiveness of the proposed controller.

  11. Coordinated path-following and direct yaw-moment control of autonomous electric vehicles with sideslip angle estimation

    Science.gov (United States)

    Guo, Jinghua; Luo, Yugong; Li, Keqiang; Dai, Yifan

    2018-05-01

    This paper presents a novel coordinated path following system (PFS) and direct yaw-moment control (DYC) of autonomous electric vehicles via hierarchical control technique. In the high-level control law design, a new fuzzy factor is introduced based on the magnitude of longitudinal velocity of vehicle, a linear time varying (LTV)-based model predictive controller (MPC) is proposed to acquire the wheel steering angle and external yaw moment. Then, a pseudo inverse (PI) low-level control allocation law is designed to realize the tracking of desired external moment torque and management of the redundant tire actuators. Furthermore, the vehicle sideslip angle is estimated by the data fusion of low-cost GPS and INS, which can be obtained by the integral of modified INS signals with GPS signals as initial value. Finally, the effectiveness of the proposed control system is validated by the simulation and experimental tests.

  12. Chirp-free direct modulation of 550 nm emission in Er3+ -Doped Fluoroindate glass by nonlinear feedback control

    Science.gov (United States)

    Cai, Runyu; Thitsa, Makhin; Bluiett, Althea; Brown, Ei; Hommerich, Uwe

    2017-06-01

    We propose a direct modulation method with nonlinear feedback controller which can produce chirp-free modulation of the output pulse without bulky external modulators. This work reports the design of the controller which, via a feedback loop, varies and controls the pump rate in real time by automatically adjusting the pump power to precisely modulate the emission of 550 nm in Er3+ -doped Fluoroindate glass under 1.48 μm pumping. In this interdisciplinary paper, well established theoretical tools from nonlinear control theory are applied to the dynamical system of the laser material in order to produce the desired output of the laser. The controller is simulated in MATLAB Simulink and the simulation results show that our technique yields precise modulation of the output intensity without frequency chirping. Results on both theoretical analysis of the control methodology and simulation are presented.

  13. Direct measurement of the plasma equilibrium response to poloidal field changes and H∞ controller tests in TCV

    International Nuclear Information System (INIS)

    Lister, J.B.; Albanese, R.; Ambrosino, G.

    2001-01-01

    The control of ITER provides several challenges which can be met using existing techniques for the design of modern controllers. The specific case of the control of the Poloidal Field (PF) system has sollicited considerable interest. One feature of the design of such controllers is their dependence on a sufficiently accurate model of the full system under control. To this end, experiments have been performed on the TCV tokamak to validate one plasma equilibrium response model, the CREATE-L model. Using a new technique, the open loop response of TCV has been directly measured in the frequency domain. These experimental results compare well with the CREATE-L model. This model was subsequently used to design a PF system controller, using methods proposed during the ITER EDA and the first test on TCV has been successful. (author)

  14. Direct measurement of the plasma equilibrium response to poloidal field changes and H∞ controller tests in TCV

    International Nuclear Information System (INIS)

    Lister, J.B.; Albanese, R.; Ambrosino, G.

    1999-01-01

    The control of ITER provides several challenges which can be met using existing techniques for the design of modern controllers. The specific case of the control of the Poloidal Field (PF) system has solicited considerable interest. One feature of the design of such controllers is their dependence on a sufficiently accurate model of the full system under control. To this end, experiments have been performed on the TCV tokamak to validate one plasma equilibrium response model, the CREATE-L model. Using a new technique, the open loop response of TCV has been directly measured in the frequency domain. These experimental results compare well with the CREATE-L model. This model was subsequently used to design a PF system controller, using methods proposed during the ITER EDA and the first test on TCV has been successful. (author)

  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. Decentralized energy management strategy based on predictive controllers for a medium voltage direct current photovoltaic electric vehicle charging station

    International Nuclear Information System (INIS)

    Torreglosa, Juan P.; García-Triviño, Pablo; Fernández-Ramirez, Luis M.; Jurado, Francisco

    2016-01-01

    Highlights: • Electric vehicle charging station supplied by photovoltaic, batteries and grid connection is analyzed. • The bus voltage is the key parameter for controlling the system by decentralized approach. • Decentralized control approach facilities the enlargement of the system. • Photovoltaic and battery systems are controlled by model predictive controllers. • Response by model predictive controllers improves that by PI controllers. - Abstract: The use of distributed charging stations based on renewable energy sources for electric vehicles has increased in recent years. Combining photovoltaic solar energy and batteries as energy storage system, directly tied into a medium voltage direct current bus, and with the grid support, results to be an interesting option for improving the operation and efficiency of electric vehicle charging stations. In this paper, an electric vehicle charging station supplied by photovoltaic solar panels, batteries and with grid connection is analysed and evaluated. A decentralized energy management system is developed for regulating the energy flow among the photovoltaic system, the battery and the grid in order to achieve the efficient charging of electric vehicles. The medium voltage direct current bus voltage is the key parameter for controlling the system. The battery is controlled by a model predictive controller in order to keep the bus voltage at its reference value. Depending on the state-of-charge of the battery and the bus voltage, the photovoltaic system can work at maximum power point tracking mode or at bus voltage sustaining mode, or even the grid support can be needed. The results demonstrate the proper operation and energy management of the electric vehicle charging station under study.

  18. A Novel Rotor and Stator Magnetic Fields Direct-Orthogonalized Vector Control Scheme for the PMSM Servo System

    Directory of Open Access Journals (Sweden)

    Shi-Xiong Zhang

    2014-02-01

    Full Text Available Permanent Magnet Synchronous motor (PMSM has received widespread acceptance in recent years. In this paper, a new rotor and stator Magnetic Fields Direct-Orthogonalized Vector Control (MFDOVC scheme is proposed for PMSM servo system. This method simplified the complex calculation of traditional vector control, a part of the system resource is economized. At the same time, through the simulation illustration validation, the performance of PMSM servo system with the proposed MFDOVC scheme can achieve the same with the complex traditional vector control method, but much simpler calculation is implemented using the proposed method.

  19. A Performance Study on Synchronous and Asynchronous Update Rules for A Plug-In Direct Particle Swarm Repetitive Controller

    Directory of Open Access Journals (Sweden)

    Ufnalski Bartlomiej

    2014-12-01

    Full Text Available In this paper two different update schemes for the recently developed plug-in direct particle swarm repetitive controller (PDPSRC are investigated and compared. The proposed approach employs the particle swarm optimizer (PSO to solve in on-line mode a dynamic optimization problem (DOP related to the control task in the constant-amplitude constant-frequency voltage-source inverter (CACF VSI with an LC output filter. The effectiveness of synchronous and asynchronous update rules, both commonly used in static optimization problems (SOPs, is assessed and compared in the case of PDPSRC. The performance of the controller, when synthesized using each of the update schemes, is studied numerically.

  20. Pilot-model measurements of pilot responses in a lateral-directional control task

    Science.gov (United States)

    Adams, J. J.

    1976-01-01

    Pilot response during an aircraft bank-angle compensatory control task was measured by using an adaptive modeling technique. In the main control loop, which is the bank angle to aileron command loop, the pilot response was the same as that measured previously in single-input, single-output systems. The pilot used a rudder to aileron control coordination that canceled up to 80 percent of the vehicle yawing moment due to aileron deflection.

  1. Applied research into direct numerical control of A-1 reactor temperature

    International Nuclear Information System (INIS)

    Karpeta, C.; Volf, K.

    1974-01-01

    Partial results of research efforts aimed at applying modern control theory in the control of the reactor of the A-1 nuclear power station are presented. A mathematical model of the process dynamics was developed. Some parameters of the model were determined using the results of an experimentally performed reactor scram. The optimal stochastic discrete regulator was determined and closed-loop transients were studied. The possibilities of implementing control routines were investigated using the RPP-16 computer. (author)

  2. Synthesis and microstructural characterization of growth direction controlled ZnO nanorods using a buffer layer

    International Nuclear Information System (INIS)

    Park, Dong Jun; Kim, Dong Chan; Lee, Jeong Yong; Cho, Hyung Koun

    2006-01-01

    The growth direction and morphology of one-dimensional ZnO nanostructures grown by metal-organic chemical vapour deposition (MOCVD) were modulated by changing the growth temperature of previously deposited ZnO buffer layers that were used as a template. The ZnO nanorods grown on the low-temperature deposited buffer layer were regularly inclined with respect to the substrate surface and show in-plane alignment with azimuthally six-fold symmetry. In contrast, deposition of the buffer layer at higher growth temperature led to the formation of vertically well-aligned ZnO nanorods. In addition, the ZnO nanorods grown on the buffer layer deposited at low growth temperature show a growth direction of [1 0 1-bar 0], unlike the conventional ZnO nanorods showing a growth direction of [0001]. The microstructural analysis and atomic modelling of the formation of regularly inclined nanorods using transmission electron microscopy are presented

  3. Minimal-Approximation-Based Distributed Consensus Tracking of a Class of Uncertain Nonlinear Multiagent Systems With Unknown Control Directions.

    Science.gov (United States)

    Choi, Yun Ho; Yoo, Sung Jin

    2017-03-28

    A minimal-approximation-based distributed adaptive consensus tracking approach is presented for strict-feedback multiagent systems with unknown heterogeneous nonlinearities and control directions under a directed network. Existing approximation-based consensus results for uncertain nonlinear multiagent systems in lower-triangular form have used multiple function approximators in each local controller to approximate unmatched nonlinearities of each follower. Thus, as the follower's order increases, the number of the approximators used in its local controller increases. However, the proposed approach employs only one function approximator to construct the local controller of each follower regardless of the order of the follower. The recursive design methodology using a new error transformation is derived for the proposed minimal-approximation-based design. Furthermore, a bounding lemma on parameters of Nussbaum functions is presented to handle the unknown control direction problem in the minimal-approximation-based distributed consensus tracking framework and the stability of the overall closed-loop system is rigorously analyzed in the Lyapunov sense.

  4. Integral Plus Resonant Sliding Mode Direct Power Control for VSC-HVDC Systems under Unbalanced Grid Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Weipeng Yang

    2017-10-01

    Full Text Available An integral plus resonant sliding mode direct power control (IRSMC DPC strategy for voltage source converter high voltage direct current (VSC-HVDC systems under unbalanced grid voltage conditions is proposed in this paper. Through detailed instantaneous power flow analysis, a generalized power compensation method, by which the ratio between the amplitude of active and reactive power ripples can be controlled continuously, is obtained. This enables the system to provide flexible power control, so that the desired performance of the system on both the ac and dc sides can be attained under different operating conditions. When the grid voltage is unbalanced, one or both of the active and reactive power terms contain ripples, oscillating at twice the grid frequency, to obtain non-distorted ac current. A power controller consisting of the proportional, integral and resonant control laws is designed using the sliding mode control approach, to achieve accurate power control objective. Simulation studies on a two-terminal VSC-HVDC system using MATLAB/SIMULINK (R2013b, Mathworks, Natick, MA, USA are conducted to verify the effectiveness of the IRSMC DPC strategy. The results show that this strategy ensures satisfactory performance of the system over a wide range of operating conditions.

  5. Comparing Treatment and Control Groups on Multiple Outcomes: Robust Procedures for Testing a Directional Alternative Hypothesis

    Science.gov (United States)

    Lix, Lisa M.; Deering, Kathleen N.; Fouladi, Rachel T.; Manivong, Phongsack

    2009-01-01

    This study considers the problem of testing the difference between treatment and control groups on m [greater than or equal to] 2 measures when it is assumed a priori that the treatment group will perform better than the control group on all measures. Two procedures are investigated that do not rest on the assumptions of covariance homogeneity or…

  6. 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...

  7. 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...... control strategies are effective means for providing ancillary frequency control of variable speed wind turbines with full-scale back-to-back power converters....... emulation, primary frequency control and secondary frequency control, are proposed in order to improve the frequency stability of power systems. The modified IEEE 39-bus test system with a large-scale wind power penetration is chosen as the studied power system. Simulation results show that the proposed...

  8. Design parameters for voltage-controllable directed assembly of single nanoparticles

    NARCIS (Netherlands)

    Porter, Benjamin F.; Abelmann, Leon; Bhaskaran, Harish

    2013-01-01

    Techniques to reliably pick-and-place single nanoparticles into functional assemblies are required to incorporate exotic nanoparticles into standard electronic circuits. In this paper we explore the use of electric fields to drive and direct the assembly process, which has the advantage of being

  9. 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.

  10. Method for exciting inductive-resistive loads with high and controllable direct current

    International Nuclear Information System (INIS)

    Hill, H.M. Jr.

    1976-01-01

    The apparatus and method for transmitting dc power to a load circuit by applying a dc voltage from a standard waveform synthesizer to duration modulate a bipolar rectangular wave generator are described. As the amplitude of the dc voltage increases, the widths of the rectangular wave generator output pulses increase, and as the amplitude of the dc voltage decreases, the widths of the rectangular wave generator output pulses decrease. Thus, the waveform synthesizer selectively changes the durations of the rectangular wave generator bipolar output pulses so as to produce a rectangular wave ac carrier that is duration modulated in accordance with and in direct proportion to the voltage amplitude from the synthesizer. Thereupon, by transferring the carrier to the load circuit through an amplifier and a rectifier, the load current also corresponds directly to the voltage amplitude from the synthesizer. To this end, the rectified wave at less than 100 percent duty factor amounts to a doubled frequency direct voltage pulse train for applying a direct current to the load, while the current ripple is minimized by a high L/R in the load circuit. In one embodiment, a power transmitting power amplifier means having a dc power supply is matched to the load circuit through a transformer for current magnification without sacrificing load current duration capability, while negative voltage and current feedback are provided in order to insure good output fidelity. 4 Claims, 18 Drawing Figures

  11. Forum: Interaction of State Aid, Free Movement, Policy Competition and Abuse Control in Direct Tax Matters

    NARCIS (Netherlands)

    Wattel, P.J.

    2013-01-01

    The European Union has woken up to State aid possibly contained in national direct tax measures. As a result, the number of Commission actions against Member States on the basis of fiscal State aid has increased in recent years, with some amazing results. It has also revealed overlap and

  12. Goal-Directed Action Control in Children with Autism Spectrum Disorders

    Science.gov (United States)

    Geurts, Hilde M; de Wit, Sanne

    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 disorders and 24 age- and gender-matched controls…

  13. 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

  14. Position Control of an Over‐Actuated Direct Hydraulic Cylinder Drive

    DEFF Research Database (Denmark)

    Schmidt, Lasse; Grønkjær, Morten; Pedersen, Henrik Clemmensen

    2017-01-01

    , and various approaches have been proposed by research communities as well as the industry. Recently, a so-called Speed-variable Switched Differential Pump was proposed for direct drive of hydraulic differential cylinders. The main idea with this drive is to utilize an electric rotary drive with the shaft...

  15. Simulation and Modeling of a New Medium Access Control Scheme for Multi-Beam Directional Networking

    Science.gov (United States)

    2017-03-03

    Multi-beam directional systems are a novel approach to networking which leverage recent advances in physical layer technology, allowing formation of...for a programmatic method for setting up emulation experiments. Rather than hard code all of the underlying pieces for EMANE (such as the over-the-air

  16. Directional semivariogram analysis to identify and rank controls on the spatial variability of fracture networks

    Science.gov (United States)

    Hanke, John R.; Fischer, Mark P.; Pollyea, Ryan M.

    2018-03-01

    In this study, the directional semivariogram is deployed to investigate the spatial variability of map-scale fracture network attributes in the Paradox Basin, Utah. The relative variability ratio (R) is introduced as the ratio of integrated anisotropic semivariogram models, and R is shown to be an effective metric for quantifying the magnitude of spatial variability for any two azimuthal directions. R is applied to a GIS-based data set comprising roughly 1200 fractures, in an area which is bounded by a map-scale anticline and a km-scale normal fault. This analysis reveals that proximity to the fault strongly influences the magnitude of spatial variability for both fracture intensity and intersection density within 1-2 km. Additionally, there is significant anisotropy in the spatial variability, which is correlated with trends of the anticline and fault. The direction of minimum spatial correlation is normal to the fault at proximal distances, and gradually rotates and becomes subparallel to the fold axis over the same 1-2 km distance away from the fault. We interpret these changes to reflect varying scales of influence of the fault and the fold on fracture network development: the fault locally influences the magnitude and variability of fracture network attributes, whereas the fold sets the background level and structure of directional variability.

  17. Consumer-Directed Community Care: Race/Ethnicity and Individual Differences in Preferences for Control

    Science.gov (United States)

    Sciegaj, Mark; Capitman, John A.; Kyriacou, Corrine Kay

    2004-01-01

    Purpose. Even though consumer-directed care models are being advocated for use among elder populations, there are few data on the extent of elder interest in participating in the management of community long-term-care services, who they want involved in making these decisions, or their perceptions regarding the relative importance of different…

  18. Bacterial foraging-optimized PID control of a two-wheeled machine with a two-directional handling mechanism.

    Science.gov (United States)

    Goher, K M; Fadlallah, S O

    2017-01-01

    This paper presents the performance of utilizing a bacterial foraging optimization algorithm on a PID control scheme for controlling a five DOF two-wheeled robotic machine with two-directional handling mechanism. The system under investigation provides solutions for industrial robotic applications that require a limited-space working environment. The system nonlinear mathematical model, derived using Lagrangian modeling approach, is simulated in MATLAB/Simulink ® environment. Bacterial foraging-optimized PID control with decoupled nature is designed and implemented. Various working scenarios with multiple initial conditions are used to test the robustness and the system performance. Simulation results revealed the effectiveness of the bacterial foraging-optimized PID control method in improving the system performance compared to the PID control scheme.

  19. 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

  20. 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... § 102-33.135 Do we have to follow the direction in OMB Circular A-123, “Management Accountability and... follow the direction in OMB Circular A-123, “Management Accountability and Control,” June 21, 1995, for...

  1. On the use of controls for subsonic transport performance improvement: Overview and future directions

    Science.gov (United States)

    Gilyard, Glenn; Espana, Martin

    1994-01-01

    Increasing competition among airline manufacturers and operators has highlighted the issue of aircraft efficiency. Fewer aircraft orders have led to an all-out efficiency improvement effort among the manufacturers to maintain if not increase their share of the shrinking number of aircraft sales. Aircraft efficiency is important in airline profitability and is key if fuel prices increase from their current low. In a continuing effort to improve aircraft efficiency and develop an optimal performance technology base, NASA Dryden Flight Research Center developed and flight tested an adaptive performance seeking control system to optimize the quasi-steady-state performance of the F-15 aircraft. The demonstrated technology is equally applicable to transport aircraft although with less improvement. NASA Dryden, in transitioning this technology to transport aircraft, is specifically exploring the feasibility of applying adaptive optimal control techniques to performance optimization of redundant control effectors. A simulation evaluation of a preliminary control law optimizes wing-aileron camber for minimum net aircraft drag. Two submodes are evaluated: one to minimize fuel and the other to maximize velocity. This paper covers the status of performance optimization of the current fleet of subsonic transports. Available integrated controls technologies are reviewed to define approaches using active controls. A candidate control law for adaptive performance optimization is presented along with examples of algorithm operation.

  2. The Effect of Faster Engine Response on the Lateral Directional Control of a Damaged Aircraft

    Science.gov (United States)

    May, Ryan D.; Lemon, Kimberly A.; Csank, Jeffrey T.; Litt, Jonathan S.; Guo, Ten-Huei

    2012-01-01

    The integration of flight control and propulsion control has been a much discussed topic, especially for emergencies where the engines may be able to help stabilize and safely land a damaged aircraft. Previous research has shown that for the engines to be effective as flight control actuators, the response time to throttle commands must be improved. Other work has developed control modes that accept a higher risk of engine failure in exchange for improved engine response during an emergency. In this effort, a nonlinear engine model (the Commercial Modular Aero-Propulsion System Simulation 40k) has been integrated with a nonlinear airframe model (the Generic Transport Model) in order to evaluate the use of enhanced-response engines as alternative yaw rate control effectors. Tests of disturbance rejection and command tracking were used to determine the impact of the engines on the aircraft's dynamical behavior. Three engine control enhancements that improve the response time of the engine were implemented and tested in the integrated simulation. The enhancements were shown to increase the engine s effectiveness as a yaw rate control effector when used in an automatic feedback loop. The improvement is highly dependent upon flight condition; the airframe behavior is markedly improved at low altitude, low speed conditions, and relatively unchanged at high altitude, high speed.

  3. Direct numerical control of machine tools in a nuclear research center by the CAMAC system

    International Nuclear Information System (INIS)

    Zwoll, K.; Mueller, K.D.; Becks, B.; Erven, W.; Sauer, M.

    1977-01-01

    The production of mechanical parts in research centers can be improved by connecting several numerically controlled machine tools to a central process computer via a data link. The CAMAC Serial Highway with its expandable structure yields an economic and flexible system for this purpose. The CAMAC System also facilitates the development of modular components controlling the machine tools itself. A CAMAC installation controlling three different machine tools connected to a central computer (PDP11) via the CAMAC Serial Highway is described. Besides this application, part of the CAMAC hardware and software can also be used for a great variety of scientific experiments

  4. Well-directed inclusion of hematology in African national cancer control plans.

    Science.gov (United States)

    Weaver, Meaghann; Yao, Atteby J J; Renner, Lorna; Harif, Mhamed; Lam, Catherine G

    2017-07-01

    In the context of a convergent call for noncommunicable disease integration in the global agenda, recognizing cross-cutting needs and opportunities in national strategies across disease fields with shared priorities in low- and middle-income settings can enhance sustainable development approaches. We reviewed publicly available cancer control plans in Africa to evaluate for inclusion of hematology needs and shared service priorities. Pediatric data remain sparse in cancer control plans. While continental Africa represents incredible diversity, recognizing shared priorities and opportunity for collaboration between oncology and hematology services and across age groups may guide prioritized cancer control efforts and reduce programmatic redundancies in resource-limited settings. © 2017 Wiley Periodicals, Inc.

  5. Light sensitive memristor with bi-directional and wavelength-dependent conductance control

    International Nuclear Information System (INIS)

    Maier, P.; Hartmann, F.; Emmerling, M.; Schneider, C.; Kamp, M.; Worschech, L.; Rebello Sousa Dias, M.; Castelano, L. K.; Marques, G. E.; Lopez-Richard, V.; Höfling, S.

    2016-01-01

    We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

  6. Light sensitive memristor with bi-directional and wavelength-dependent conductance control

    Energy Technology Data Exchange (ETDEWEB)

    Maier, P.; Hartmann, F., E-mail: fabian.hartmann@physik.uni-wuerzburg.de; Emmerling, M.; Schneider, C.; Kamp, M.; Worschech, L. [Technische Physik and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Physikalisches Institut, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Rebello Sousa Dias, M. [Departamento de Fisica, Universidade Federal de São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Castelano, L. K.; Marques, G. E.; Lopez-Richard, V. [Departamento de Fisica, Universidade Federal de São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Höfling, S. [Technische Physik and Wilhelm Conrad Röntgen Research Center for Complex Material Systems, Physikalisches Institut, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS (United Kingdom)

    2016-07-11

    We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories.

  7. Improvement of the directional stability of passenger car trailer couplings with actively controlled steering

    Science.gov (United States)

    Desens, Jens

    The stabilization of pendulum oscillations of passenger car trailer couplings, using active steering, was examined. A linear model of the couplings was presented. Each axle was provided with a controller. The controllers were optimized, with regard to necessary sensors, in order to minimize costs. The rear and the front axles were provided with a control unit in order to compute the potential prevailing in the active steering of several axles. It was shown that the passenger car rear axle was the most suitable for coupling stabilization. The experiment was simulated, using a complex coupling model. The developed controller allowed the passenger car trailer to be driven at a speed higher than 150 km per hour.

  8. Direct Digital Control of HVAC (Heating, Ventilating, and Air Conditioning Equipment (User’s Guide)

    Science.gov (United States)

    1985-01-01

    reset, load shedding, chiller optimization , VAV fan synchronization, and optimum start/stop. The prospective buyer of a DDC system should investigate...current and accurate drawings for a conventional, built-up control system such as that illustrated in Fig- ure 4. Data on setpoints , reset schedules, and...are always available in the form of the computer program code (Figure 7). In addition to the control logic, setpoint and other data are readily

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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...... 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....

  14. ACCOUNTING AND ANALYTICAL PROCUREMENT OF STATE FINANCIAL CONTROL AND DIRECTIONS OF ITS IMPLEMENTATION IN UKRAINE

    Directory of Open Access Journals (Sweden)

    Iryna Maksymenko

    2017-12-01

    Full Text Available The growth of the constructive role of public financial control in management is a logical consequence of the modernization of the established system of state financial control and necessitates an update of the ideology and paradigmatic principles of state financial control. A retrospective review of the theoretical and practical aspects of the methodology and organization in the state financial control of Ukraine suggests that in the scientific environment these issues are studied extensively. However, despite the scientific and practical value of these works, the question of the possible modernization of the modern system of state financial control in the conditions of Ukraine’s integration into the world economic system remains unresolved for the time being and is still the subject of lively discussions. The subject of the study is theoretical and methodological principles and methods for the implementation of state financial control, as well as the results of the activities of the State Audit Office of Ukraine for 2017. The purpose of the study is to substantiate the theoretical positions of the system of state financial control in Ukraine, to analyse the activity of the State Audit Service of Ukraine for 2017, and to suggest ways to improve it. To achieve the research goal, the following questions are addressed and solved: the analysis of the activity of the State Audit Service of Ukraine was carried out, based on the results of which the financial impropriety and state of its elimination for 2017 were described; the analysis revealed an increased attention to the organization of an effective system of financial control of budgetary institutions, the continuous improvement of mechanisms of management and control over budgetary funds. Method. To achieve the defined goal, a complex of general scientific and special methods was used: the method of system analysis and complex structures formalization; generalization and scientific abstraction

  15. Fuzzy-predictive direct power control implementation of a grid connected photovoltaic system, associated with an active power filter

    International Nuclear Information System (INIS)

    Ouchen, Sabir; Betka, Achour; Abdeddaim, Sabrina; Menadi, Abdelkrim

    2016-01-01

    Highlights: • An implementation on dSPACE 1104 of a double stage grid connected photovoltaic system, associated with an active power filter. • A fuzzy logic controller for maximum power point tracking of photovoltaic generator using a boost converter. • Predictive direct power control almost eliminates the effect of harmonics under a unite power factor. • The robustness of control strategies was examined in different irradiance level conditions. - Abstract: The present paper proposes a real time implementation of an optimal operation of a double stage grid connected photovoltaic system, associated with a shunt active power filter. On the photovoltaic side, a fuzzy logic based maximum power point taking control is proposed to track permanently the optimum point through an adequate tuning of a boost converter regardless the solar irradiance variations; whereas, on the grid side, a model predictive direct power control is applied, to ensure both supplying a part of the load demand with the extracted photovoltaic power, and a compensation of undesirable harmonic contents of the grid current, under a unity power factor operation. The implementation of the control strategies is conducted on a small scale photovoltaic system, controlled via a dSPACE 1104 single card. The obtained experimental results show on one hand, that the proposed Fuzzy logic based maximum power taking point technique provides fast and high performances under different irradiance levels while compared with a sliding mode control, and ensures 1.57% more in efficiency. On the other hand, the predictive power control ensures a flexible settlement of active power amounts exchanges with the grid, under a unity power functioning. Furthermore, the grid current presents a sinusoidal shape with a tolerable total harmonic distortion coefficient 4.71%.

  16. Direct Flux Control for Stand-Alone Operation Brushless Doubly Fed Induction Generators Using a Resonant-Based Sliding-Mode Control Approach

    Directory of Open Access Journals (Sweden)

    Kai Ji

    2018-04-01

    Full Text Available In this paper, a novel voltage control strategy for stand-alone operation brushless doubly fed induction generators for variable speed constant frequency wind energy conversion systems was presented and discussed. Based on the model of the power generation system, the proposed direct flux control strategy employs a nonlinear reduced-order generalized integrator-based resonant sliding-mode control approach to directly calculate and regulate the output value of converter which the control winding stator requires so as to eliminate its instantaneous errors, without involving any synchronous rotating coordinate transformations. The stability, robustness and convergence capability of the proposed control strategy were described and analyzed. Owing to the fact no additional current control inner loops are involved, the system configuration is therefore simplified and the dynamic performance enhanced. A constant converter switching frequency was achieved by using space vector pulse width modulation, which reduces the harmonics of the generator terminal voltage. In addition, the feasibility and validity of the proposed scheme is verified by experiments, and excellent steady and transient performance is achieved.

  17. The establishment and application of direct coupled electrostatic-structural field model in electrostatically controlled deployable membrane antenna

    Science.gov (United States)

    Gu, Yongzhen; Duan, Baoyan; Du, Jingli

    2018-05-01

    The electrostatically controlled deployable membrane antenna (ECDMA) is a promising space structure due to its low weight, large aperture and high precision characteristics. However, it is an extreme challenge to describe the coupled field between electrostatic and membrane structure accurately. A direct coupled method is applied to solve the coupled problem in this paper. Firstly, the membrane structure and electrostatic field are uniformly described by energy, considering the coupled problem is an energy conservation phenomenon. Then the direct coupled electrostatic-structural field governing equilibrium equations are obtained by energy variation approach. Numerical results show that the direct coupled method improves the computing efficiency by 36% compared with the traditional indirect coupled method with the same level accuracy. Finally, the prototype has been manufactured and tested and the ECDMA finite element simulations show good agreement with the experiment results as the maximum surface error difference is 6%.

  18. 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.

  19. Direct potentiometric control of chloride-ion content in water coolant of nuclear reactors

    International Nuclear Information System (INIS)

    Moskvin, L.N.; Vilkov, N.Ya.; Krasnoperov, V.M.; Epimakhova, L.V.

    1979-01-01

    The work of automatic chloride measuring device designed for continuous determination of chloride-ion concentration in water coolants of nuclear power plants is investigated. A series of experiments have been performed to investigate a device with sensitive element in the form of potentiometric cell with two flowing porous metal silver electrodes (PSE), placed in series. A calibration circuit of chloride measuring devices and PSE is described. A comparison is made between the results obtained by means of automatic chloride measuring device and results of manual control of samples. A conclusion is drawn that automatic chloride measuring devices meet the requirements of nuclear power plants for methods and instruments of control of chloride-ions microconcentration. The development and implantation of automatic chloride-ion analizers will make the analytical control on nuclear power plants easier and make it possible to obtain more reliable information

  20. Direct continuous multichannel γspectrometric measurements- one of the main methods for control and study of radioactive environmental pollution

    International Nuclear Information System (INIS)

    Khitrov, L.M.; Rumiantsev, O.V.

    1991-01-01

    In Chernobyl along with usual methods of environment radiation control there were used methods and equipment of direct continuous multichannel measurements. The necessary equipment was installed both on permanent observation stations (river Pripyat, Chernobyl, river Dnieper, Kiev) and on mobile units (helicopters, scientific river-boats, automobiles). Together with continuous control of radioactive situation and its estimation in time and space this equipment enabled to carry out the following: - determination of time-spatial structure of radioactive pollution in stationary points and on space (mapping); - selection of representative samples for subsequent radionuclide analysis; - direct data input into the computer, data storage and data base creation. The results and conclusions drawn are important not only for the situation on Chernobyl atomic station - they may and should be used for a continuous radioactive monitoring of the environment. Though the method and its realization remain to be modernized and unified. (author)

  1. Preliminary Studies on Aerodynamic Control with Direct Current Discharge at Hypersonic Speed

    Science.gov (United States)

    Watanabe, Yasumasa; Takama, Yoshiki; Imamura, Osamu; Watanuki, Tadaharu; Suzuki, Kojiro

    A new idea of an aerodynamic control device for hypersonic vehicles using plasma discharges is presented. The effect of DC plasma discharge on a hypersonic flow is examined with both experiments and CFD analyses. It is revealed that the surface pressure upstream of plasma area significantly increases, which would be preferable in realizing a new aerodynamic control devices. Such pressure rise is also observed in the result of analyses of the Navier-Stokes equations with energy addition that simulates the Joule heating of a plasma discharge. It is revealed that the pressure rise due to the existence of the plasma discharge can be qualitatively explained as an effect of Joule heating.

  2. Controlled drilling technology for HLW management. Directional drilling and mechanics/stress measurements in the borehole

    International Nuclear Information System (INIS)

    Kiho, Kenzo; Shin, Koichi; Okada, Tetsuji; Obuchi, Yasuyoshi; Sunaga, Takayuki; Hase, Kazunori

    2013-01-01

    Since 2000, Central Research Institute of Electric Power Industry (CRIEPI) has been conducting the project on controlled drilling and the logging/measurement technologies in its boreholes. Especially borehole pressure meter and bore hole stress measurement apparatus which can apply to the controlled drilling system was developed. The bore hole was drilled to the 1000 m long in order to intersect the Omagari fault located at Horonobe town in Hokkaido and its core recovery was 99.8% as of FY. 2011. Using borehole logging/measurement/survey, the geological, hydrological, geo-mechanical, geophysical and geochemical data were collected and the Omagari fault was characterized. (author)

  3. [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.

  4. 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

    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......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...

  5. 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…

  6. 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, lymphati...

  7. Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

    DEFF Research Database (Denmark)

    Sun, Jie; Lindvall, Niclas; Cole, Matthew T.

    2012-01-01

    Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinholes...

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

    NARCIS (Netherlands)

    G.R. Williams (Gareth); K. Fierens (Kaat); S.G. Preston (Stephen); A.C. Lunn; O. Rysnik (Oliwia); S. de Prijck (Sofie); M. Kool (Mirjam); H.C. Buckley (Hannah); B.N.M. Lambrecht (Bart); D. O'Hare (Dermot); J.M. Austyn (Jonathan)

    2014-01-01

    textabstractThere is currently no paradigm in immunology that enables an accurate prediction of how the immune system will respond to any given agent. Here we show that the immunological responses induced by members of a broad class of inorganic crystalline materials are controlled purely by their

  9. Temporal coding of brain patterns for direct limb control in humans

    Directory of Open Access Journals (Sweden)

    Gernot Mueller-Putz

    2010-06-01

    Full Text Available For individuals with a high spinal cord injury (SCI not only the lower limbs, but also the upper extremities are paralyzed. A neuroprosthesis can be used to restore the lost hand and arm function in those tetraplegics. The main problem for this group of individuals, however, is the reduced ability to voluntarily operate device controllers. A Brain-Computer Interface provides a non-manual alternative to conventional input devices by translating brain activity patterns into control commands. We show that the temporal coding of individual mental imagery pattern can be used to control two independent degrees of freedom – grasp and elbow function - of an artificial robotic arm by utilizing a minimum number of EEG scalp electrodes. We describe the procedure from the initial screening to the final application. From eight naïve subjects participating on-line feedback experiments, four were able to voluntarily control an artificial arm by inducing one motor imagery pattern derived from one EEG derivation only.

  10. 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…

  11. Direct model-based predictive control scheme without cost function for voltage source inverters with reduced common-mode voltage

    Science.gov (United States)

    Kim, Jae-Chang; Moon, Sung-Ki; Kwak, Sangshin

    2018-04-01

    This paper presents a direct model-based predictive control scheme for voltage source inverters (VSIs) with reduced common-mode voltages (CMVs). The developed method directly finds optimal vectors without using repetitive calculation of a cost function. To adjust output currents with the CMVs in the range of -Vdc/6 to +Vdc/6, the developed method uses voltage vectors, as finite control resources, excluding zero voltage vectors which produce the CMVs in the VSI within ±Vdc/2. In a model-based predictive control (MPC), not using zero voltage vectors increases the output current ripples and the current errors. To alleviate these problems, the developed method uses two non-zero voltage vectors in one sampling step. In addition, the voltage vectors scheduled to be used are directly selected at every sampling step once the developed method calculates the future reference voltage vector, saving the efforts of repeatedly calculating the cost function. And the two non-zero voltage vectors are optimally allocated to make the output current approach the reference current as close as possible. Thus, low CMV, rapid current-following capability and sufficient output current ripple performance are attained by the developed method. The results of a simulation and an experiment verify the effectiveness of the developed method.

  12. A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range

    Directory of Open Access Journals (Sweden)

    Wenzheng Xu

    2017-10-01

    Full Text Available Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS and Zero Voltage Switching (ZVS in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains.

  13. 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.

  14. Future directions in controlling the LAMPF-PSR Accelerator Complex at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Stuewe, R.; Schaller, S.; Bjorklund, E.; Burns, M.; Callaway, T.; Carr, G.; Cohen, S.; Kubicek, D.; Harrington, M.; Poore, R.; Schultz, D.

    1991-01-01

    Four interrelated projects are underway whose purpose is to migrate the LAMPF-PSR Accelerator Complex control systems to a system with a common set of hardware and software components. Project goals address problems in performance, maintenance and growth potential. Front-end hardware, operator interface hardware and software, computer systems, network systems and data system software are being simultaneously upgraded as part of these efforts. The efforts are being coordinated to provide for a smooth and timely migration to a client-sever model-based data acquisition and control system. An increased use of the distributed intelligence at both the front-end and operator interface is a key element of the projects. 2 refs., 2 figs

  15. Directing Reaction Pathways through Controlled Reactant Binding at Pd-TiO2 Interfaces.

    Science.gov (United States)

    Zhang, Jing; Wang, Bingwen; Nikolla, Eranda; Medlin, J Will

    2017-06-01

    Recent efforts to design selective catalysts for multi-step reactions, such as hydrodeoxygenation (HDO), have emphasized the preparation of active sites at the interface between two materials having different properties. However, achieving precise control over interfacial properties, and thus reaction selectivity, has remained a challenge. Here, we encapsulated Pd nanoparticles (NPs) with TiO 2 films of regulated porosity to gain a new level of control over catalyst performance, resulting in essentially 100 % HDO selectivity for two biomass-derived alcohols. This catalyst also showed exceptional reaction specificity in HDO of furfural and m-cresol. In addition to improving HDO activity by maximizing the interfacial contact between the metal and metal oxide sites, encapsulation by the nanoporous oxide film provided a significant selectivity boost by restricting the accessible conformations of aromatics on the surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Future directions in controlling the LAMPF-PSR accelerator complex at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Stuewe, R.; Schaller, S.; Bjorklund, E.

    1992-01-01

    Four interrelated projects are underway whose purpose is to migrate the LAMPF-PSR Accelerator Complex control systems to a system with a common set of hardware and software components. Project goals address problems in performance, maintenance and growth potential. Front-end hardware, operator interface hardware and software, computer systems, network systems and data system software are being simultaneously upgraded as part of these efforts. The efforts are being coordinated to provide for a smooth and timely migration to a client-server model-based data acquisition and control system. An increased use of distributed intelligence at both the front-end and the operator interface is a key element of the projects. (author)

  17. Power Extraction Control of Variable Speed Wind Turbine Systems Based on Direct Drive Synchronous Generator in All Operating Regimes

    Directory of Open Access Journals (Sweden)

    Youssef Errami

    2018-01-01

    Full Text Available Due to the increased penetration of wind energy into the electrical power systems in recent years, the turbine controls are actively occupied in the research. This paper presents a nonlinear backstepping strategy to control the generators and the grid sides of a Wind Farm System (WFS based Direct Drive Synchronous Generator (DDSG. The control objectives such as Tracking the Maximum Power (TMP from the WFS, pitch control, regulation of dc-link voltage, and reactive and active power generation at varying wind velocity are included. To validate the proposed control strategy, simulation results for 6-MW-DDSG based Wind Farm System are carried out by MATLAB-Simulink. Performance comparison and evaluation with Vector Oriented Control (VOC are provided under a wide range of functioning conditions, three-phase voltage dips, and the probable occurrence of uncertainties. The proposed control strategy offers remarkable characteristics such as excellent dynamic and steady state performance under varying wind speed and robustness to parametric variations in the WFS and under severe faults of grid voltage.

  18. Users Guide to Direct Digital Control of Heating, Ventilating, and Air Conditioning Equipment,

    Science.gov (United States)

    1985-01-01

    cycles, reset, load shedding, chiller optimization , VAV fan synchronization, and optimum start/stop. The prospective buyer of a DDC system should...in Fig- ure 4. Data on setpoints , reset schedules, and event timing, such as that presented in Figure 6, are often even more difficult to find. In con...control logic, setpoint and other data are readily available. Program logic, setpoint and schedule data, and other information stored in a DDC unit

  19. Generation Following with Thermostatically Controlled Loads via Alternating Direction Method of Multipliers Sharing Algorithm

    OpenAIRE

    Burger, Eric M.; Moura, Scott J.

    2015-01-01

    A fundamental requirement of the electric power system is to maintain a continuous and instantaneous balance between generation and load. The intermittency and uncertainty introduced by renewable energy generation requires the expansion of ancillary power system services to maintain such a balance. In this paper, we examine the potential of thermostatically controlled loads (TCLs), such as refrigerators and electric water heaters, to provide generation following services in real-time energy m...

  20. Policy issues on the control of major accident hazards and the new Seveso II directive

    International Nuclear Information System (INIS)

    Porter, S.; Wettig, J.

    1999-01-01

    No one wants a major accident to occur! This paper describes the development of EC policies to convert this simple and obvious fact into a coherent prevention strategy which can deliver a high level of protection throughout the European Community. The Seveso II Directive is described in detail, being the relevant Community Instrument which Member States must implement in their national laws. The need to achieve the correct balance between setting general goals and being over prescriptive is discussed, commensurate with the intent to be flexible but yet consistent and effective at the same time. The main changes from Seveso I are discussed, including requirements related to the operator's management systems, the competent authority's systems for inspection, and information and consultation arrangements with the public. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  1. Application of Fungicides and Microalgal Phenolic Extracts for the Direct Control of Fumonisin Contamination in Maize.

    Science.gov (United States)

    Scaglioni, Priscila Tessmer; Blandino, Massimo; Scarpino, Valentina; Giordano, Debora; Testa, Giulio; Badiale-Furlong, Eliana

    2018-05-16

    Fungicides and, for the first time, microalgal phenolic extracts (MPE) from Spirulina sp. and Nannochloropsis sp. were applied on maize culture media under field conditions to evaluate their ability to minimize Fusarium species development and fumonisin production. An in vitro assay against F. verticillioides was carried out using maize grains as the culture medium. An open-field experiment was carried out in Northwest Italy under natural infection conditions. The compared treatments were factorial combinations of two insecticide treatments (an untreated control and pyrethroid, used against European Corn Borer), four antifungal treatments (an untreated control, MPE from Spirulina sp., MPE from Nannochloropsis sp., and a synthetic fungicide), and two timings of the application of the antifungal compounds (at maize flowering and at the milk stage). The MPE compounds were capable of inhibiting fumonisin production in vitro more efficiently than tebuconazole. Insecticide application reduced the infection by Fusarium species and subsequent fumonisin contamination. However, fumonisins in maize fields were not significantly controlled by either fungicide or MPE application.

  2. Optimal control of gun recoil in direct fire using magnetorheological absorbers

    International Nuclear Information System (INIS)

    Singh, Harinder J; Wereley, Norman M

    2014-01-01

    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. (paper)

  3. 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.

  4. Controlling the optical performance of transparent conducting oxides using direct laser interference patterning

    International Nuclear Information System (INIS)

    Berger, Jana; Roch, Teja; Correia, Stelio; Eberhardt, Jens; Lasagni, Andrés Fabián

    2016-01-01

    In this study, a laser based process called Direct Laser Interference Patterning (DLIP) was used to fabricate micro-textured boron doped zinc oxide (ZnO:B) thin films to be used as electrodes in thin-film silicon solar cells. First, the ablation thresholds of the ZnO:B film were determined using a nanosecond pulsed laser at wavelengths of 266 and 355 nm (100 mJ/cm"2 and 89 mJ/cm"2, respectively). After that, DLIP experiments were performed at 355 nm wavelength. Line-like periodic surface structures with spatial periods ranging from 0.8 to 5.0 μm were fabricated using two interfering laser beams. It was found that the structuring process of the transparent conducting oxide (TCO) is mainly based on a photo-thermal mechanism. The surface of the ZnO:B film was molten and evaporated at the interference maxima positions and the depth and width of the generated microfeatures depend on the laser parameters as well as the spatial period of the interference pattern. The optical properties of the structured TCOs were investigated as a function of the utilized laser processing parameters. Both diffuse and total transmission and the intensity of the diffraction orders were determined. These data were used to calculate the increase of the optical path of the transmitted light. - Highlights: • Direct Laser Interference Patterning (DLIP) on boron doped zinc oxide (LPCVD-ZnO:B) • No relevant decrease of total transmission • Periods of 1.5 μm provide large diffraction angle and good diffraction intensity. • Significant increase of optical path length could be reached.

  5. Controlling the optical performance of transparent conducting oxides using direct laser interference patterning

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Jana; Roch, Teja [Fraunhofer-Institut für Werkstoff-und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden (Germany); Technische Universität Dresden, Institute of Manufacturing Technology, George-Baehr-Str.1, 01069 Dresden (Germany); Correia, Stelio; Eberhardt, Jens [Bosch Solar Energy AG, August-Broemel-Str. 6, 99310 Arnstadt (Germany); Lasagni, Andrés Fabián, E-mail: andres_fabian.lasagni@tu-dresden.de [Fraunhofer-Institut für Werkstoff-und Strahltechnik IWS, Winterbergstr. 28, 01277 Dresden (Germany); Technische Universität Dresden, Institute of Manufacturing Technology, George-Baehr-Str.1, 01069 Dresden (Germany)

    2016-08-01

    In this study, a laser based process called Direct Laser Interference Patterning (DLIP) was used to fabricate micro-textured boron doped zinc oxide (ZnO:B) thin films to be used as electrodes in thin-film silicon solar cells. First, the ablation thresholds of the ZnO:B film were determined using a nanosecond pulsed laser at wavelengths of 266 and 355 nm (100 mJ/cm{sup 2} and 89 mJ/cm{sup 2}, respectively). After that, DLIP experiments were performed at 355 nm wavelength. Line-like periodic surface structures with spatial periods ranging from 0.8 to 5.0 μm were fabricated using two interfering laser beams. It was found that the structuring process of the transparent conducting oxide (TCO) is mainly based on a photo-thermal mechanism. The surface of the ZnO:B film was molten and evaporated at the interference maxima positions and the depth and width of the generated microfeatures depend on the laser parameters as well as the spatial period of the interference pattern. The optical properties of the structured TCOs were investigated as a function of the utilized laser processing parameters. Both diffuse and total transmission and the intensity of the diffraction orders were determined. These data were used to calculate the increase of the optical path of the transmitted light. - Highlights: • Direct Laser Interference Patterning (DLIP) on boron doped zinc oxide (LPCVD-ZnO:B) • No relevant decrease of total transmission • Periods of 1.5 μm provide large diffraction angle and good diffraction intensity. • Significant increase of optical path length could be reached.

  6. '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

  7. An Enhanced Three-Level Voltage Switching State Scheme for Direct Torque Controlled Open End Winding Induction Motor

    Science.gov (United States)

    Kunisetti, V. Praveen Kumar; Thippiripati, Vinay Kumar

    2018-01-01

    Open End Winding Induction Motors (OEWIM) are popular for electric vehicles, ship propulsion applications due to less DC link voltage. Electric vehicles, ship propulsions require ripple free torque. In this article, an enhanced three-level voltage switching state scheme for direct torque controlled OEWIM drive is implemented to reduce torque and flux ripples. The limitations of conventional Direct Torque Control (DTC) are: possible problems during low speeds and starting, it operates with variable switching frequency due to hysteresis controllers and produces higher torque and flux ripple. The proposed DTC scheme can abate the problems of conventional DTC with an enhanced voltage switching state scheme. The three-level inversion was obtained by operating inverters with equal DC-link voltages and it produces 18 voltage space vectors. These 18 vectors are divided into low and high frequencies of operation based on rotor speed. The hardware results prove the validity of proposed DTC scheme during steady-state and transients. From simulation and experimental results, proposed DTC scheme gives less torque and flux ripples on comparison to two-level DTC. The proposed DTC is implemented using dSPACE DS-1104 control board interface with MATLAB/SIMULINK-RTI model.

  8. Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control

    International Nuclear Information System (INIS)

    McGovern, Scott; Alici, Gursel; Spinks, Geoffrey; Truong, Van-Tan

    2009-01-01

    This paper presents the development of an autonomously powered and controlled robotic fish that incorporates an active flexural joint tail fin, activated through conducting polymer actuators based on polypyrrole (PPy). The novel electromaterial muscle oscillator (NEMO) tail fin assembly on the fish could be controlled wirelessly in real time by varying the frequency and duty cycle of the voltage signal supplied to the PPy bending-type actuators. Directional control was achieved by altering the duty cycle of the voltage input to the NEMO tail fin, which shifted the axis of oscillation and enabled turning of the robotic fish. At low speeds, the robotic fish had a turning circle as small as 15 cm (or 1.1 body lengths) in radius. The highest speed of the fish robot was estimated to be approximately 33 mm s −1 (or 0.25 body lengths s −1 ) and was achieved with a flapping frequency of 0.6–0.8 Hz which also corresponded with the most hydrodynamically efficient mode for tail fin operation. This speed is approximately ten times faster than those for any previously reported artificial muscle based device that also offers real-time speed and directional control. This study contributes to previously published studies on bio-inspired functional devices, demonstrating that electroactive polymer actuators can be real alternatives to conventional means of actuation such as electric motors

  9. Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control

    Science.gov (United States)

    McGovern, Scott; Alici, Gursel; Truong, Van-Tan; Spinks, Geoffrey

    2009-09-01

    This paper presents the development of an autonomously powered and controlled robotic fish that incorporates an active flexural joint tail fin, activated through conducting polymer actuators based on polypyrrole (PPy). The novel electromaterial muscle oscillator (NEMO) tail fin assembly on the fish could be controlled wirelessly in real time by varying the frequency and duty cycle of the voltage signal supplied to the PPy bending-type actuators. Directional control was achieved by altering the duty cycle of the voltage input to the NEMO tail fin, which shifted the axis of oscillation and enabled turning of the robotic fish. At low speeds, the robotic fish had a turning circle as small as 15 cm (or 1.1 body lengths) in radius. The highest speed of the fish robot was estimated to be approximately 33 mm s-1 (or 0.25 body lengths s-1) and was achieved with a flapping frequency of 0.6-0.8 Hz which also corresponded with the most hydrodynamically efficient mode for tail fin operation. This speed is approximately ten times faster than those for any previously reported artificial muscle based device that also offers real-time speed and directional control. This study contributes to previously published studies on bio-inspired functional devices, demonstrating that electroactive polymer actuators can be real alternatives to conventional means of actuation such as electric motors.

  10. Improved direct torque control of an induction generator used in a wind conversion system connected to the grid.

    Science.gov (United States)

    Abdelli, Radia; Rekioua, Djamila; Rekioua, Toufik; Tounzi, Abdelmounaïm

    2013-07-01

    This paper presents a modulated hysteresis direct torque control (MHDTC) applied to an induction generator (IG) used in wind energy conversion systems (WECs) connected to the electrical grid through a back-to-back converter. The principle of this strategy consists in superposing to the torque reference a triangular signal, as in the PWM strategy, with the desired switching frequency. This new modulated reference is compared to the estimated torque by using a hysteresis controller as in the classical direct torque control (DTC). The aim of this new approach is to lead to a constant frequency and low THD in grid current with a unit power factor and a minimum voltage variation despite the wind variation. To highlight the effectiveness of the proposed method, a comparison was made with classical DTC and field oriented control method (FOC). The obtained simulation results, with a variable wind profile, show an adequate dynamic of the conversion system using the proposed method compared to the classical approaches. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  11. 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.

  12. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. High-directivity planar antenna using controllable photonic bandgap material at microwave frequencies

    International Nuclear Information System (INIS)

    de Lustrac, A.; Gadot, F.; Akmansoy, E.; Brillat, T.

    2001-01-01

    In this letter, we experimentally demonstrate the capability of a controllable photonic bandgap (CPBG) material to conform the emitted radiation of a planar antenna at 12 GHz. The CPBG material is a variable conductance lattice fabricated with high-frequency PIN diodes soldered along metallic stripes on dielectric printed boards. Depending on the diode bias, the emitted radiation of the antenna can be either transmitted or totally reflected by the material. In the transmission state, the antenna radiation is spatially filtered by the CPBG material in a sharp beam perpendicular to the surface of the material. [copyright] 2001 American Institute of Physics

  14. Direct subwavelength imaging and control of near-field localization in individual silver nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Mårsell, Erik; Svärd, Robin; Miranda, Miguel; Guo, Chen; Harth, Anne; Lorek, Eleonora; Mauritsson, Johan; Arnold, Cord L.; L' Huillier, Anne; Mikkelsen, Anders; Losquin, Arthur, E-mail: arthur.losquin@fysik.lth.se [Department of Physics, Lund University, PO Box 118, 221 00 Lund (Sweden); Xu, Hongxing [Department of Physics, Lund University, PO Box 118, 221 00 Lund (Sweden); School of Physics and Technology and Institute for Advanced Studies, Wuhan University, Wuhan 430072 (China)

    2015-11-16

    We demonstrate the control of near-field localization within individual silver nanocubes through photoemission electron microscopy combined with broadband, few-cycle laser pulses. We find that the near-field is concentrated at the corners of the cubes, and that it can be efficiently localized to different individual corners depending on the polarization of the incoming light. The experimental results are confirmed by finite-difference time-domain simulations, which also provide an intuitive picture of polarization dependent near-field localization in nanocubes.

  15. Improved Direct Power Control for Grid-Connected Voltage Source Converters

    DEFF Research Database (Denmark)

    Gui, Yonghao; Kim, Chunghun; Chung, Chung Choo

    2018-01-01

    easily. The GVM-DPC guarantees not only the convergence rate but also the steady-state performance of the system. Moreover, it is ensured that the closed-loop system is exponentially stable. Finally, simulation and experimental results using a 2.2-kVA VSC are provided to validate the tracking performance...... and robustness of the proposed control architecture. In addition, the total harmonic distortion of the current is 1.9% which is much less than the requirement for grid operation....

  16. Polarization control of direct (non-sequential) two-photon double ionization of He

    International Nuclear Information System (INIS)

    Pronin, E A; Manakov, N L; Marmo, S I; Starace, Anthony F

    2007-01-01

    An ab initio parametrization of the doubly-differential cross section (DDCS) for two-photon double ionization (TPDI) from an s 2 subshell of an atom in a 1 S 0 -state is presented. Analysis of the elliptic dichroism (ED) effect in the DDCS for TPDI of He and its comparison with the same effect in the concurrent process of sequential double ionization shows their qualitative and quantitative differences, thus providing a means to control and to distinguish sequential and non-sequential processes by measuring the relative ED parameter

  17. A method exploiting direct communication between phasor measurement units for power system wide-area protection and control algorithms.

    Science.gov (United States)

    Almas, Muhammad Shoaib; Vanfretti, Luigi

    2017-01-01

    Synchrophasor measurements from Phasor Measurement Units (PMUs) are the primary sensors used to deploy Wide-Area Monitoring, Protection and Control (WAMPAC) systems. PMUs stream out synchrophasor measurements through the IEEE C37.118.2 protocol using TCP/IP or UDP/IP. The proposed method establishes a direct communication between two PMUs, thus eliminating the requirement of an intermediate phasor data concentrator, data mediator and/or protocol parser and thereby ensuring minimum communication latency without considering communication link delays. This method allows utilizing synchrophasor measurements internally in a PMU to deploy custom protection and control algorithms. These algorithms are deployed using protection logic equations which are supported by all the PMU vendors. Moreover, this method reduces overall equipment cost as the algorithms execute internally in a PMU and therefore does not require any additional controller for their deployment. The proposed method can be utilized for fast prototyping of wide-area measurements based protection and control applications. The proposed method is tested by coupling commercial PMUs as Hardware-in-the-Loop (HIL) with Opal-RT's eMEGAsim Real-Time Simulator (RTS). As illustrative example, anti-islanding protection application is deployed using proposed method and its performance is assessed. The essential points in the method are: •Bypassing intermediate phasor data concentrator or protocol parsers as the synchrophasors are communicated directly between the PMUs (minimizes communication delays).•Wide Area Protection and Control Algorithm is deployed using logic equations in the client PMU, therefore eliminating the requirement for an external hardware controller (cost curtailment)•Effortless means to exploit PMU measurements in an environment familiar to protection engineers.

  18. Power control for direct-driven permanent magnet wind generator system with battery storage.

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient.

  19. Semi-quantum communication: protocols for key agreement, controlled secure direct communication and dialogue

    Science.gov (United States)

    Shukla, Chitra; Thapliyal, Kishore; Pathak, Anirban

    2017-12-01

    Semi-quantum protocols that allow some of the users to remain classical are proposed for a large class of problems associated with secure communication and secure multiparty computation. Specifically, first-time semi-quantum protocols are proposed for key agreement, controlled deterministic secure communication and dialogue, and it is shown that the semi-quantum protocols for controlled deterministic secure communication and dialogue can be reduced to semi-quantum protocols for e-commerce and private comparison (socialist millionaire problem), respectively. Complementing with the earlier proposed semi-quantum schemes for key distribution, secret sharing and deterministic secure communication, set of schemes proposed here and subsequent discussions have established that almost every secure communication and computation tasks that can be performed using fully quantum protocols can also be performed in semi-quantum manner. Some of the proposed schemes are completely orthogonal-state-based, and thus, fundamentally different from the existing semi-quantum schemes that are conjugate coding-based. Security, efficiency and applicability of the proposed schemes have been discussed with appropriate importance.

  20. Power Control for Direct-Driven Permanent Magnet Wind Generator System with Battery Storage

    Directory of Open Access Journals (Sweden)

    Chu Xiao Guang

    2014-01-01

    Full Text Available 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.

  1. Direct and indirect links between parenting styles, self-concealment (secrets), impaired control over drinking and alcohol-related outcomes.

    Science.gov (United States)

    Hartman, Jessica D; Patock-Peckham, Julie A; Corbin, William R; Gates, Jonathan R; Leeman, Robert F; Luk, Jeremy W; King, Kevin M

    2015-01-01

    Self-concealment reflects uncomfortable feelings, thoughts, and information people have about themselves that they avoid telling others (Larson & Chastain, 1990). According to Larson and Chastain (1990) these secrets range from the slightly embarrassing to the very distressing with an individual's most traumatic experiences often concealed. Parental attitudes including those involving self-disclosure are thought to be expressed in their choice of parenting style (Brand, Hatzinger, Beck, & Holsboer-Trachsler, 2009). The specific aim of this investigation was to examine the direct and indirect influences of parenting styles on self-concealment, impaired control over drinking (i.e. the inability to stop drinking when intended), alcohol use (quantity/frequency), and alcohol-related problems. A structural equation model with 419 (223 men, 196 women) university students was examined. Two and three path mediated effects were examined with the bias corrected bootstrap technique in Mplus. Having an authoritarian mother was directly linked to more self-concealment, while having an authoritative father was directly linked to less self-concealment. Higher levels of mother authoritarianism were indirectly linked to both increased alcohol use and alcohol-related problems through more self-concealment and more impaired control over drinking. Moreover, higher levels of father authoritativeness were indirectly linked to less alcohol use and alcohol-related problems through less self-concealment and less impaired control over drinking. These findings suggest that parenting styles influence vulnerabilities such as self-concealment in the impaired control over the drinking pathway to alcohol use and alcohol-related problems. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Direct evidence for sequence-dependent attraction between double-stranded DNA controlled by methylation.

    Science.gov (United States)

    Yoo, Jejoong; Kim, Hajin; Aksimentiev, Aleksei; Ha, Taekjip

    2016-03-22

    Although proteins mediate highly ordered DNA organization in vivo, theoretical studies suggest that homologous DNA duplexes can preferentially associate with one another even in the absence of proteins. Here we combine molecular dynamics simulations with single-molecule fluorescence resonance energy transfer experiments to examine the interactions between duplex DNA in the presence of spermine, a biological polycation. We find that AT-rich DNA duplexes associate more strongly than GC-rich duplexes, regardless of the sequence homology. Methyl groups of thymine acts as a steric block, relocating spermine from major grooves to interhelical regions, thereby increasing DNA-DNA attraction. Indeed, methylation of cytosines makes attraction between GC-rich DNA as strong as that between AT-rich DNA. Recent genome-wide chromosome organization studies showed that remote contact frequencies are higher for AT-rich and methylated DNA, suggesting that direct DNA-DNA interactions that we report here may play a role in the chromosome organization and gene regulation.

  3. Controlling the stainless steel surface wettability by nanosecond direct laser texturing at high fluences

    Science.gov (United States)

    Gregorčič, P.; Šetina-Batič, B.; Hočevar, M.

    2017-12-01

    This work investigates the influence of the direct laser texturing at high fluences (DLT-HF) on surface morphology, chemistry, and wettability. We use a Nd:YAG laser ( λ = 1064 nm) with pulse duration of 95 ns to process stainless steel surface. The surface morphology and chemistry after the texturing is examined by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD), while the surface wettability is evaluated by measuring the static contact angle. Immediately after the texturing, the surface is superhydrophilic in a saturated Wenzel regime. However, this state is not stable and the superhydrophilic-to-superhydrophobic transition happens if the sample is kept in atmospheric air for 30 days. After this period, the laser-textured stainless steel surface expresses lotus-leaf-like behavior. By using a high-speed camera at 10,000 fps, we measured that the water droplet completely rebound from this superhydrophobic surface after the contact time of 12 ms.

  4. Crustal Density Variation Along the San Andreas Fault Controls Its Secondary Faults Distribution and Dip Direction

    Science.gov (United States)

    Yang, H.; Moresi, L. N.

    2017-12-01

    The San Andreas fault forms a dominant component of the transform boundary between the Pacific and the North American plate. The density and strength of the complex accretionary margin is very heterogeneous. Based on the density structure of the lithosphere in the SW United States, we utilize the 3D finite element thermomechanical, viscoplastic model (Underworld2) to simulate deformation in the San Andreas Fault system. The purpose of the model is to examine the role of a big bend in the existing geometry. In particular, the big bend of the fault is an initial condition of in our model. We first test the strength of the fault by comparing the surface principle stresses from our numerical model with the in situ tectonic stress. The best fit model indicates the model with extremely weak fault (friction coefficient 200 kg/m3) than surrounding blocks. In contrast, the Mojave block is detected to find that it has lost its mafic lower crust by other geophysical surveys. Our model indicates strong strain localization at the jointer boundary between two blocks, which is an analogue for the Garlock fault. High density lower crust material of the Great Valley tends to under-thrust beneath the Transverse Range near the big bend. This motion is likely to rotate the fault plane from the initial vertical direction to dip to the southwest. For the straight section, north to the big bend, the fault is nearly vertical. The geometry of the fault plane is consistent with field observations.

  5. Design and fabrication of conductive polyaniline transducers via computer controlled direct ink writing

    Science.gov (United States)

    Holness, F. Benjamin; Price, Aaron D.

    2017-04-01

    The intractable nature of the conjugated polymer (CP) polyaniline (PANI) has largely limited PANI-based transducers to monolithic geometries derived from thin-film deposition techniques. To address this limitation, we have previously reported additive manufacturing processes for the direct ink writing of three-dimensional electroactive PANI structures. This technology incorporates a modified delta robot having an integrated polymer paste extrusion system in conjunction with a counter-ion induced thermal doping process to achieve these 3D structures. In this study, we employ an improved embodiment of this methodology for the fabrication of functional PANI devices with increasingly complex geometries and enhanced electroactive functionality. Advances in manufacturing capabilities achieved through the integration of a precision pneumatic fluid dispenser and redesigned high-pressure end-effector enable extrusion of viscous polymer formulations, improving the realizable resolutions of features and deposition layers. The integration of a multi-material dual-extrusion end-effector has further aided the fabrication of these devices, enabling the concurrent assembly of passive and active structures, which reduces the limitations on device geometry. Subsequent characterization of these devices elucidates the relationships between polymer formulation, process parameters, and device design such that electromechanical properties can be tuned according to application requirements. This methodology ultimately leads to the improved manufacturing of electroactive polymer-enabled devices with high-resolution 3D features and enhanced electroactive performance.

  6. Simulation of the Dynamic Behavior of an Asynchronous Machine Using Direct Self-Control

    Directory of Open Access Journals (Sweden)

    Cristian Paul Chioncel

    2007-01-01

    Full Text Available The paper presents the major steps that have to be gone for the implementation of the mathematical model of the asynchronous machine in SciLab / Scicos. This implemented ASM model, will be used to check the dynamic behavior of the system, the current diagrams as well as the behavior motor speed and the torque, if the input signal has a pulsation form. This implementation’s are made in Scilab / Scicos environment, a clone of the MATLAB, which provides number-crunching power similar to MATLAB, at a much better cost/performance ratio. The implemented model offers the possibility to analyze the behaviors of the asynchronous machine in different dynamic situations: speed, torques, current in motor or generator regime and to study its behavior in different possible control schemes.

  7. Subscale Flight Testing for Aircraft Loss of Control: Accomplishments and Future Directions

    Science.gov (United States)

    Cox, David E.; Cunningham, Kevin; Jordan, Thomas L.

    2012-01-01

    Subscale flight-testing provides a means to validate both dynamic models and mitigation technologies in the high-risk flight conditions associated with aircraft loss of control. The Airborne Subscale Transport Aircraft Research (AirSTAR) facility was designed to be a flexible and efficient research facility to address this type of flight-testing. Over the last several years (2009-2011) it has been used to perform 58 research flights with an unmanned, remotely-piloted, dynamically-scaled airplane. This paper will present an overview of the facility and its architecture and summarize the experimental data collected. All flights to date have been conducted within visual range of a safety observer. Current plans for the facility include expanding the test volume to altitudes and distances well beyond visual range. The architecture and instrumentation changes associated with this upgrade will also be presented.

  8. Admixture enhanced controlled low-strength material for direct underwater injection with minimal cross-contamination

    International Nuclear Information System (INIS)

    Hepworth, H.K.; Davidson, J.S.; Hooyman, J.L.

    1997-01-01

    Commercially available admixtures have been developed for placing traditional concrete products under water. This paper evaluates adapting anti-washout admixture (AWA) and high range water reducing admixture (HRWRA) products to enhance controlled low-strength materials (CLSMs) for underwater placement. A simple experimental scale model (based on dynamic and geometric similitude) of typical grout pump emplacement equipment has been developed to determine the percentage of cementing material washed out. The objective of this study was to identify proportions of admixtures and underwater CLSM emplacement procedures which would minimize the cross-contamination of the displaced water while maintaining the advantages of CLSM. Since the displaced water from radioactively contaminated systems must be subsequently treated prior to release to the environment, the amount of cross-contamination is important for cases in which cementing material could form hard sludges in a water treatment facility and contaminate the in-place CLSM stabilization medium

  9. 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.

  10. Improving temporal bone dissection using self-directed virtual reality simulation: results of a randomized blinded control trial.

    Science.gov (United States)

    Zhao, Yi Chen; Kennedy, Gregor; Yukawa, Kumiko; Pyman, Brian; O'Leary, Stephen

    2011-03-01

    A significant benefit of virtual reality (VR) simulation is the ability to provide self-direct learning for trainees. This study aims to determine whether there are any differences in performance of cadaver temporal bone dissections between novices who received traditional teaching methods and those who received unsupervised self-directed learning in a VR temporal bone simulator. Randomized blinded control trial. Royal Victorian Eye and Ear Hospital. Twenty novice trainees. After receiving an hour lecture, participants were randomized into 2 groups to receive an additional 2 hours of training via traditional teaching methods or self-directed learning using a VR simulator with automated guidance. The simulation environment presented participants with structured training tasks, which were accompanied by real-time computer-generated feedback as well as real operative videos and photos. After the training, trainees were asked to perform a cortical mastoidectomy on a cadaveric temporal bone. The dissection was videotaped and assessed by 3 otologists blinded to participants' teaching group. The overall performance scores of the simulator-based training group were significantly higher than those of the traditional training group (67% vs 29%; P < .001), with an intraclass correlation coefficient of 0.93, indicating excellent interrater reliability. Using other assessments of performance, such as injury size, the VR simulator-based training group also performed better than the traditional group. This study indicates that self-directed learning on VR simulators can be used to improve performance on cadaver dissection in novice trainees compared with traditional teaching methods alone.

  11. Effects of Transcranial Direct-Current Stimulation on Neurosurgical Skill Acquisition: A Randomized Controlled Trial.

    Science.gov (United States)

    Ciechanski, Patrick; Cheng, Adam; Lopushinsky, Steven; Hecker, Kent; Gan, Liu Shi; Lang, Stefan; Zareinia, Kourosh; Kirton, Adam

    2017-12-01

    Recent changes in surgical training environments may have limited opportunities for trainees to gain proficiency in skill. Complex skills such as neurosurgery require extended periods of training. Methods to enhance surgical training are required to overcome duty-hour restrictions, to ensure the acquisition of skill proficiency. Transcranial direct-current stimulation (tDCS) can enhance motor skill learning, but is untested in surgical procedural training. We aimed to determine the effects of tDCS on simulation-based neurosurgical skill acquisition. Medical students were trained to acquire tumor resection skills using a virtual reality neurosurgical simulator. The primary outcome of change in tumor resection was scored at baseline, over 8 repetitions, post-training, and again at 6 weeks. Participants received anodal tDCS or sham over the primary motor cortex. Secondary outcomes included changes in brain resected, resection effectiveness, duration of excessive forces (EF) applied, and resection efficiency. Additional outcomes included tDCS tolerability. Twenty-two students consented to participate, with no dropouts over the course of the trial. Participants receiving tDCS intervention increased the amount of tumor resected, increased the effectiveness of resection, reduced the duration of EF applied, and improved resection efficiency. Little or no decay was observed at 6 weeks in both groups. No adverse events were documented, and sensation severity did not differ between stimulation groups. The addition of tDCS to neurosurgical training may enhance skill acquisition in a simulation-based environment. Trials of additional skills in high-skill residents, and translation to nonsimulated performance are needed to determine the potential utility of tDCS in surgical training. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Onchocerciasis control in Nigeria: will households be able to afford community-directed treatment with ivermectin?

    Science.gov (United States)

    Onwujekwe, O; Shu, E; Onwuameze, O; Ndum, C; Okonkwo, P

    2001-12-21

    To determine the level of affordability of community-directed treatment with ivermectin (CDTI) to households living in two onchocerciasis endemic Nigerian communities namely Toro in the north and Nike in the south. The proportion of the cost of treating people with ivermectin will deplete in average monthly/projected annual household expenditure on food and health care, and on average monthly and projected annual household income were respectively calculated and used to determine the level of affordability of CDTI. Questionnaires administered to heads of households or their representatives were used to collect information on the household expenditures and income. The suggested unit CDTI cost of $0.20 was used. However, as a test of sensitivity, we also used the unit cost of $0.056 which some community based distributors are charging per treatment. Using $0.20 as the unit treatment cost, this will consume less than 0.05% of average annual household income in both communities. It will equally deplete 0.05% of combined annual household expenditures on food and health care in both communities. However, using $0.056 as the unit treatment cost, then 0.02% of average annual household expenditure on health care, 0.01% average annual expenditure on combined health care and food, and 0.01% of average annual household income will be depleted. The households living in both communities may be able to afford CDTI schemes. However, the final decision on levels of affordability lies with the households. They will decide whether they can afford to trade-off some household income for ivermectin distribution.

  13. A mathematical model for the control of carrier-dependent infectious diseases with direct transmission and time delay

    International Nuclear Information System (INIS)

    Misra, A.K.; Mishra, S.N.; Pathak, A.L.; Srivastava, P.K.; Chandra, Peeyush

    2013-01-01

    In this paper, a non-linear delay mathematical model for the control of carrier-dependent infectious diseases through insecticides is proposed and analyzed. In the modeling process, it is assumed that disease spreads due to direct contact between susceptibles and infectives as well as through carriers (indirect contact). Further, it is assumed that insecticides are used to kill carriers and the rate of introduction of insecticides is proportional to the density of carriers with some time lag. The model analysis suggests that as delay in using insecticides exceeds some critical value, the system loses its stability and Hopf-bifurcation occurs. The direction, stability and period of the bifurcating periodic solutions arising through Hopf-bifurcation are also analyzed using normal form concept and center manifold theory. Numerical simulation is carried out to confirm the obtained analytical results

  14. The impact of blended teaching on knowledge, satisfaction, and self-directed learning in nursing undergraduates: a randomized, controlled trial.

    Science.gov (United States)

    Gagnon, Marie-Pierre; Gagnon, Johanne; Desmartis, Marie; Njoya, Merlin

    2013-01-01

    This study aimed to assess the effectiveness of a blended-teaching intervention using Internet-based tutorials coupled with traditional lectures in an introduction to research undergraduate nursing course. Effects of the intervention were compared with conventional, face-to-face classroom teaching on three outcomes: knowledge, satisfaction, and self-learning readiness. A two-group, randomized, controlled design was used, involving 112 participants. Descriptive statistics and analysis of covariance (ANCOVA) were performed. The teaching method was found to have no direct impact on knowledge acquisition, satisfaction, and self-learning readiness. However, motivation and teaching method had an interaction effect on knowledge acquisition by students. Among less motivated students, those in the intervention group performed better than those who received traditional training. These findings suggest that this blended-teaching method could better suit some students, depending on their degree of motivation and level of self-directed learning readiness.

  15. A Coral Reef Algorithm Based on Learning Automata for the Coverage Control Problem of Heterogeneous Directional Sensor Networks.

    Science.gov (United States)

    Li, Ming; Miao, Chunyan; Leung, Cyril

    2015-12-04

    Coverage control is one of the most fundamental issues in directional sensor networks. In this paper, the coverage optimization problem in a directional sensor network is formulated as a multi-objective optimization problem. It takes into account the coverage rate of the network, the number of working sensor nodes and the connectivity of the network. The coverage problem considered in this paper is characterized by the geographical irregularity of the sensed events and heterogeneity of the sensor nodes in terms of sensing radius, field of angle and communication radius. To solve this multi-objective problem, we introduce a learning automata-based coral reef algorithm for adaptive parameter selection and use a novel Tchebycheff decomposition method to decompose the multi-objective problem into a single-objective problem. Simulation results show the consistent superiority of the proposed algorithm over alternative approaches.

  16. 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.

  17. Voluntary Control of Residual Antagonistic Muscles in Transtibial Amputees: Feedforward Ballistic Contractions and Implications for Direct Neural Control of Powered Lower Limb Prostheses.

    Science.gov (United States)

    Huang, Stephanie; Huang, He

    2018-04-01

    muscle activation patterns and direct continuous proportional myoelectric control.

  18. Quantifying direct effects of social determinants of health on glycemic control in adults with type 2 diabetes.

    Science.gov (United States)

    Walker, Rebekah J; Gebregziabher, Mulugeta; Martin-Harris, Bonnie; Egede, Leonard E

    2015-02-01

    The aim of this study was to investigate if self-care is the pathway through which social determinants of health impact diabetes outcomes by analyzing the direct and indirect effects of socioeconomic and psychosocial factors on self-care and glycemic control. Six hundred fifteen adults were recruited from two primary care clinics in the southeastern United States. A series of confirmatory factor analyses identified the latent factors underlying social status, psychosocial determinants (psychological distress, self-efficacy, and social support), and self-care (diet, exercise, foot care, glucose testing, and medication adherence). Structured equation modeling investigated the relationship among social determinants, self-care and glycemic control. Latent variables were created for diabetes self-care, psychological distress, self-efficacy, social support, and social status. The final model [χ(2)(275)=450.07, Psocial support (r=0.14, P=0.01), and higher self-efficacy (r=0.47, Psocial support (r=0.10, P=0.02), and higher self-efficacy (r=-0.37, Psocial determinants of health variables were included in the model, self-care was no longer significantly associated with glycemic control (r=0.01, P=0.83). This study suggests a direct relationship between psychosocial determinants of health and glycemic control. Although associated with self-care, the relationship between social determinants of health and glycemic control is not mediated by self-care. Development of interventions should take psychosocial factors into account as independent influences on diabetes outcomes, rather than as indirect influences via self-care behavior.

  19. 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.

  20. Review of droop-controlled bi-directional inverter in conducting islanded operation of photovoltaic systems

    Science.gov (United States)

    Khaw, Ace Lin Yi; Wong, Jianhui; Lim, Yun Seng

    2017-04-01

    Global warming due to the excessive greenhouse gas emissions has led to the emergence of green technologies in Malaysia, particularly photovoltaic (PV) systems. Under the current regulatory framework, islanded operation of the PV system is not permissible. As a result, any renewable energy sources will be disconnected immediately in the event of grid outages. This practice is to ensure the safety of working personnel, as well as the customer equipment connected within the distribution networks. In addition, there is no synchronizing equipment to aid the reconnection of the islanded network to the grid. However, with the shutdown of the Distributed Generator (DG) during islanded operation, the customers are not able to utilize the available renewable energy and the number of power interruption is not improved with the renewable energy sources. Therefore, the main objective of this paper is to investigate the feasibility of the PV system in conducting islanding operation with the use of Energy Storage System (ESS). This paper also proposes a control algorithm to maintain the voltage and frequency excursion within the statutory limit by manipulating the real and reactive power flow of the ESS within the transition period between grid connected and islanding operation.

  1. 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.

  2. Observer-Based Perturbation Extremum Seeking Control with Input Constraints for Direct-Contact Membrane Distillation Process

    KAUST Repository

    Eleiwi, Fadi

    2017-05-08

    An Observer-based Perturbation Extremum Seeking Control (PESC) is proposed for a Direct-Contact Membrane Distillation (DCMD) process. The process is described with a dynamic model that is based on a 2D Advection-Diffusion Equation (ADE) model which has pump flow rates as process inputs. The objective of the controller is to optimize the trade-off between the permeate mass flux and the energy consumption by the pumps inside the process. Cases of single and multiple control inputs are considered through the use of only the feed pump flow rate or both the feed and the permeate pump flow rates. A nonlinear Lyapunov-based observer is designed to provide an estimation for the temperature distribution all over the designated domain of the DCMD process. Moreover, control inputs are constrained with an anti-windup technique to be within feasible and physical ranges. Performance of the proposed structure is analyzed, and simulations based on real DCMD process parameters for each control input are provided.

  3. Extraction of Lateral-Directional Stability and Control Derivatives for the Basic F-18 Aircraft at High Angles of Attack

    Science.gov (United States)

    Iliff, Kenneth W.; Wang, Kon-Sheng Charles

    1997-01-01

    The results of parameter identification to determine the lateral-directional stability and control derivatives of an F-18 research aircraft in its basic hardware and software configuration are presented. The derivatives are estimated from dynamic flight data using a specialized identification program developed at NASA Dryden Flight Research Center. The formulation uses the linearized aircraft equations of motions in their continuous/discrete form and a maximum likelihood estimator that accounts for both state and measurement noise. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics, such as separated and vortical flows, over the aircraft. The derivatives are plotted as functions of angle of attack between 3 deg and 47 deg and compared with wind-tunnel predictions. The quality of the derivative estimates obtained by parameter identification is somewhat degraded because the maneuvers were flown with the aircraft's control augmentation system engaged, which introduced relatively high correlations between the control variables and response variables as a result of control motions from the feedback control system.

  4. 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.

  5. Observer-based perturbation extremum seeking control with input constraints for direct-contact membrane distillation process

    Science.gov (United States)

    Eleiwi, Fadi; Laleg-Kirati, Taous Meriem

    2018-06-01

    An observer-based perturbation extremum seeking control is proposed for a direct-contact membrane distillation (DCMD) process. The process is described with a dynamic model that is based on a 2D advection-diffusion equation model which has pump flow rates as process inputs. The objective of the controller is to optimise the trade-off between the permeate mass flux and the energy consumption by the pumps inside the process. Cases of single and multiple control inputs are considered through the use of only the feed pump flow rate or both the feed and the permeate pump flow rates. A nonlinear Lyapunov-based observer is designed to provide an estimation for the temperature distribution all over the designated domain of the DCMD process. Moreover, control inputs are constrained with an anti-windup technique to be within feasible and physical ranges. Performance of the proposed structure is analysed, and simulations based on real DCMD process parameters for each control input are provided.

  6. Modelling the role of intrinsic electric fields in microtubules as an additional control mechanism of bi-directional intracellular transport.

    Science.gov (United States)

    Sataric, M V; Budinski-Petkovic, L; Loncarevic, I; Tuszynski, J A

    2008-01-01

    Active transport is essential for cellular function, while impaired transport has been linked to diseases such as neuronal degeneration. Much long distance transport in cells uses opposite polarity molecular motors of the kinesin and dynein families to move cargos along microtubules. It is clear that many types of cargo are moved by both sets of motors, and frequently in a reverse direction. The general question of how the direction of transport is regulated is still open. The mechanism of the cell's differential control of diverse cargos within the same cytoplasmic background is still unclear as is the answer to the question how endosomes and mitochondria move to different locations within the same cell. To answer these questions we postulate the existence of a local signaling mechanism used by the cell to specifically control different cargos. In particular, we propose an additional physical mechanism that works through the use of constant and alternating intrinsic (endogenous) electric fields as a means of controlling the speed and direction of microtubule-based transport. A specific model is proposed and analyzed in this paper. The model involves the rotational degrees of freedom of the C-termini of tubulin, their interactions and the coupling between elastic and dielectric degrees of freedom. Viscosity of the solution is also included and the resultant equation of motion is found as a nonlinear elliptic equation with dissipation. A particular analytical solution of this equation is obtained in the form of a kink whose properties are analyzed. It is concluded that this solution can be modulated by the presence of electric fields and hence may correspond to the observed behavior of motor protein transport along microtubules.

  7. 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.

  8. 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.

  9. Effectiveness of transcranial direct current stimulation preceding cognitive behavioural management for chronic low back pain: sham controlled double blinded randomised controlled trial.

    Science.gov (United States)

    Luedtke, Kerstin; Rushton, Alison; Wright, Christine; Jürgens, Tim; Polzer, Astrid; Mueller, Gerd; May, Arne

    2015-04-16

    To evaluate the effectiveness of transcranial direct current stimulation alone and in combination with cognitive behavioural management in patients with non-specific chronic low back pain. Double blind parallel group randomised controlled trial with six months' follow-up conducted May 2011-March 2013. Participants, physiotherapists, assessors, and analyses were blinded to group allocation. Interdisciplinary chronic pain centre. 135 participants with non-specific chronic low back pain >12 weeks were recruited from 225 patients assessed for eligibility. Participants were randomised to receive anodal (20 minutes to motor cortex at 2 mA) or sham transcranial direct current stimulation (identical electrode position, stimulator switched off after 30 seconds) for five consecutive days immediately before cognitive behavioural management (four week multidisciplinary programme of 80 hours). Two primary outcome measures of pain intensity (0-100 visual analogue scale) and disability (Oswestry disability index) were evaluated at two primary endpoints after stimulation and after cognitive behavioural management. Analyses of covariance with baseline values (pain or disability) as covariates showed that transcranial direct current stimulation was ineffective for the reduction of pain (difference between groups on visual analogue scale 1 mm (99% confidence interval -8.69 mm to 6.3 mm; P=0.68)) and disability (difference between groups 1 point (-1.73 to 1.98; P=0.86)) and did not influence the outcome of cognitive behavioural management (difference between group 3 mm (-10.32 mm to 6.73 mm); P=0.58; difference between groups on Oswestry disability index 0 point (-2.45 to 2.62); P=0.92). The stimulation was well tolerated with minimal transitory side effects. This results of this trial on the effectiveness of transcranial direct current stimulation for the reduction of pain and disability do not support its clinical use for managing non-specific chronic low back pain

  10. Cooperative learning neural network output feedback control of uncertain nonlinear multi-agent systems under directed topologies

    Science.gov (United States)

    Wang, W.; Wang, D.; Peng, Z. H.

    2017-09-01

    Without assuming that the communication topologies among the neural network (NN) weights are to be undirected and the states of each agent are measurable, the cooperative learning NN output feedback control is addressed for uncertain nonlinear multi-agent systems with identical structures in strict-feedback form. By establishing directed communication topologies among NN weights to share their learned knowledge, NNs with cooperative learning laws are employed to identify the uncertainties. By designing NN-based κ-filter observers to estimate the unmeasurable states, a new cooperative learning output feedback control scheme is proposed to guarantee that the system outputs can track nonidentical reference signals with bounded tracking errors. A simulation example is given to demonstrate the effectiveness of the theoretical results.

  11. Accurate torque control of a bi-directional magneto-rheological actuator considering hysteresis and friction effects

    Science.gov (United States)

    Nguyen, Phuong-Bac; Choi, Seung-Bok

    2013-05-01

    This paper presents a novel type of magneto-rheological (MR) actuator called a bi-directional magneto-rheological (BMR) actuator and accurate torque control results considering both hysteresis and friction compensation. The induced torque of this actuator varies from negative to positive values. As a result, it can work as either a brake or a clutch depending on the scheme of current input. In our work, the configuration of the actuator as well as its driving system is presented first. Subsequently, a congruency hysteresis based (CBH) model to take account of the effect of the hysteresis is proposed. After that, a compensator based on this model is developed. In addition, the effect of dry friction, which exists inherently with MR actuators in general, is also considered. In order to assess the effectiveness of the hysteresis compensator, several experiments on modeling and control of the actuator with different waveforms are carried out.

  12. Accurate torque control of a bi-directional magneto-rheological actuator considering hysteresis and friction effects

    International Nuclear Information System (INIS)

    Nguyen, Phuong-Bac; Choi, Seung-Bok

    2013-01-01

    This paper presents a novel type of magneto-rheological (MR) actuator called a bi-directional magneto-rheological (BMR) actuator and accurate torque control results considering both hysteresis and friction compensation. The induced torque of this actuator varies from negative to positive values. As a result, it can work as either a brake or a clutch depending on the scheme of current input. In our work, the configuration of the actuator as well as its driving system is presented first. Subsequently, a congruency hysteresis based (CBH) model to take account of the effect of the hysteresis is proposed. After that, a compensator based on this model is developed. In addition, the effect of dry friction, which exists inherently with MR actuators in general, is also considered. In order to assess the effectiveness of the hysteresis compensator, several experiments on modeling and control of the actuator with different waveforms are carried out. (paper)

  13. 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. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

  14. 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...... is introduced in the controller, which is necessary in order to reduce the dc-bus voltage ripple and active power harmonics at the same time. The proposed control topology is implemented in the lab. Simulation and experimental results are provided to validate its performance and the analysis presented...

  15. 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, Nish; Porta, Massimo; Klein, Ronald

    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 ...

  16. 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.

  17. Arbitrary Control of Polarization and Intensity Profiles of Diffraction-Attenuation-Resistant Beams along the Propagation Direction

    Science.gov (United States)

    Corato-Zanarella, Mateus; Dorrah, Ahmed H.; Zamboni-Rached, Michel; Mojahedi, Mo

    2018-02-01

    We report on the theory and experimental generation of a class of diffraction-attenuation-resistant beams with state of polarization (SOP) and intensity that can be controlled on demand along the propagation direction. This control is achieved by a suitable superposition of Bessel beams, whose parameters are systematically chosen based on closed-form analytic expressions provided by the frozen waves method. Using an amplitude-only spatial light modulator, we experimentally demonstrate three scenarios. In the first, the SOP of a horizontally polarized beam evolves to radial polarization and is then changed to vertical polarization, with the beam intensity held constant. In the second, we simultaneously control the SOP and the longitudinal intensity profile, which is chosen such that the beam's central ring can be switched off over predefined space regions, thus generating multiple foci with different SOPs and at different intensity levels along the propagation. Finally, the ability to control the SOP while overcoming attenuation inside lossy fluids is shown experimentally. We envision our proposed method to be of great interest for many applications, such as optical tweezers, atom guiding, material processing, microscopy, and optical communications.

  18. Operation characteristic analysis of a direct methanol fuel cell system using the methanol sensor-less control method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.Y.; Chang, C.L. [Institute of Nuclear Energy Research (INER), Longtan Township, Taoyuan County (China); Sung, C.C. [National Taiwan University (China)

    2012-10-15

    The application of methanol sensor-less control in a direct methanol fuel cell (DMFC) system eliminates most of the problems encountered when using a methanol sensor and is one of the major solutions currently used in commercial DMFCs. This study focuses on analyzing the effect of the operating characteristics of a DMFC system on its performance under the methanol sensor-less control as developed by Institute of Nuclear Energy Research (INER). Notably, the influence of the dispersion of the methanol injected on the behavior of the system is investigated systematically. In addition, the mechanism of the methanol sensor-less control is investigated by varying factors such as the timing of the injection of methanol, the cathode flow rate, and the anode inlet temperature. These results not only provide insight into the mechanism of methanol sensor-less control but can also aid in the improvement and application of DMFC systems in portable and low-power transportation. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. 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.

  20. Estimating the Impacts of Direct Load Control Programs Using GridPIQ, a Web-Based Screening Tool

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Seemita; Thayer, Brandon L.; Barrett, Emily L.; Studarus, Karen E.

    2017-11-13

    In direct load control (DLC) programs, utilities can curtail the demand of participating loads to contractually agreed-upon levels during periods of critical peak load, thereby reducing stress on the system, generation cost, and required transmission and generation capacity. Participating customers receive financial incentives. The impacts of implementing DLC programs extend well beyond peak shaving. There may be a shift of load proportional to the interrupted load to the times before or after a DLC event, and different load shifts have different consequences. Tools that can quantify the impacts of such programs on load curves, peak demand, emissions, and fossil fuel costs are currently lacking. The Grid Project Impact Quantification (GridPIQ) screening tool includes a Direct Load Control module, which takes into account project-specific inputs as well as the larger system context in order to quantify the impacts of a given DLC program. This allows users (utilities, researchers, etc.) to test and compare different program specifications and their impacts.

  1. Grid Compatibility of Variable Speed Wind Turbines with Directly Coupled Synchronous Generator and Hydro-Dynamically Controlled Gearbox

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, H.; Poeller, M. [DIgSILENT GmbH, 72810 Gomaringen (Germany); Basteck, A.; Tilscher, M.; Pfister, J. [Voith Turbo GmbH and Co. KG, 74564 Crailsheim (Germany)

    2006-07-01

    This paper analyzes grid integration aspects of a new type of variable-speed wind turbine, the directly coupled synchronous generator with hydro-dynamically controlled gearbox. In contrast to existing wind generators using synchronous generators, the generator of this concept is directly connected to the AC grid, without the application of any power electronics converter. Variable speed operation of the turbine is mechanically achieved by a gear box with continuously controllable variable gear box ratio. For this purpose, a detailed dynamic model of a 2 MW wind turbine with a Voith WinDrive has been implemented using the modelling environment of the simulation software DIgSILENT PowerFactory. For investigating grid compatibility aspects of this new wind generator concept, a model of a 50 MW wind farm, with typical layout, based on 25 wind turbines of the 2 MW-class has been analyzed. This paper focuses on the compatibility of the new concept with existing connection standards, such as the E.ON grid code. Of special interest are typical stability phenomena of synchronous generators, such as transient and oscillatory stability as well as power quality issues like voltage flicker. The results of stability studies are presented and possible advantages of the new concept with special focus on offshore applications are discussed.

  2. 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.

  3. Clinical characteristics and management of patients with atrial fibrillation treated with direct oral anticoagulants according to blood pressure control.

    Science.gov (United States)

    de la Figuera, M; Cinza, S; Egocheaga, I; Marín, N; Prieto, M A

    2018-02-14

    To determine the clinical characteristics and management of hypertensive patients with nonvalvular atrial fibrillation (AF) treated with direct oral anticoagulants (DOACs) according to blood pressure (BP) control. For this purpose, data from two observational, cross-sectional and multicenter studies were combined. In both studies, patients on chronic treatment with anticoagulants and that were on current treatment with DOACs at least for 3 months were included. Adequate BP was defined as a systolic BP<140mmHg and a diastolic BP<90mmHg (<140/85mmHg if diabetes). Overall, 1036 patients were included. Of these, 881 (85%) had hypertension that were finally analyzed. The presence of other risk factors and cardiovascular disease was common. Mean BP was 132.6±14.3/75.2±9.2mmHg and 70.5% of patients achieved BP goals. Those patients with a poor BP control had more frequently diabetes, and a history of prior labile INR. Patients had a high thromboembolic risk, but without significant differences according to BP control. By contrast, more patients with a poor BP control had a higher bleeding risk (HAS-BLED ≥3: 24.0% vs 35.4%; P<0.001). HAS-BLED score was an independent predictor of poor BP control (odds ratio 1.435; 95% confidence interval 1.216-1.693; P<0.001). Satisfaction with anticoagulant treatment was independent of BP control. More than two thirds of our patients with hypertension and AF anticoagulated with DOACs achieve BP targets, what is clearly superior to that reported in the general hypertensive population. Copyright © 2018 SEH-LELHA. Publicado por Elsevier España, S.L.U. All rights reserved.

  4. Bi-directional vibration control of offshore wind turbines using a 3D pendulum tuned mass damper

    Science.gov (United States)

    Sun, C.; Jahangiri, V.

    2018-05-01

    Offshore wind turbines suffer from excessive bi-directional vibrations due to wind-wave misalignment and vortex induced vibrations. However, most of existing research focus on unidirectional vibration attenuation which is inadequate for real applications. The present paper proposes a three dimensional pendulum tuned mass damper (3d-PTMD) to mitigate the tower and nacelle dynamic response in the fore-aft and side-side directions. An analytical model of the wind turbine coupled with the 3d-PTMD is established wherein the interaction between the blades, the tower and the 3d-PTMD is modeled. Aerodynamic loading is computed using the Blade Element Momentum method where the Prandtls tip loss factor and the Glauert correction are considered. JONSWAP spectrum is adopted to generate wave data. Wave loading is computed using Morisons equation in collaboration with the strip theory. Via a numerical search approach, the design formula of the 3d-PTMD is obtained and examined on a National Renewable Energy Lab (NREL) monopile 5 MW baseline wind turbine model under misaligned wind, wave and seismic loading. Dual linear tuned mass dampers (TMDs) deployed in the fore-aft and side-side directions are utilized for comparison. It is found that the 3d-PTMD with a mass ratio of 2 % can improve the mitigation of the root mean square and peak response by around 10 % when compared with the dual linear TMDs in controlling the bi-directional vibration of the offshore wind turbines under misaligned wind, wave and seismic loading.

  5. Combined effects of cerebellar transcranial direct current stimulation and transcutaneous spinal direct current stimulation on robot-assisted gait training in patients with chronic brain stroke: A pilot, single blind, randomized controlled trial.

    Science.gov (United States)

    Picelli, Alessandro; Chemello, Elena; Castellazzi, Paola; Filippetti, Mirko; Brugnera, Annalisa; Gandolfi, Marialuisa; Waldner, Andreas; Saltuari, Leopold; Smania, Nicola

    2018-01-01

    Preliminary evidence showed additional effects of anodal transcranial direct current stimulation over the damaged cerebral hemisphere combined with cathodal transcutaneous spinal direct current stimulation during robot-assisted gait training in chronic stroke patients. This is consistent with the neural organization of locomotion involving cortical and spinal control. The cerebellum is crucial for locomotor control, in particular for avoidance of obstacles, and adaptation to novel conditions during walking. Despite its key role in gait control, to date the effects of transcranial direct current stimulation of the cerebellum have not been investigated on brain stroke patients treated with robot-assisted gait training. To evaluate the effects of cerebellar transcranial direct current stimulation combined with transcutaneous spinal direct current stimulation on robot-assisted gait training in patients with chronic brain stroke. After balanced randomization, 20 chronic stroke patients received ten, 20-minute robot-assisted gait training sessions (five days a week, for two consecutive weeks) combined with central nervous system stimulation. Group 1 underwent on-line cathodal transcranial direct current stimulation over the contralesional cerebellar hemisphere + cathodal transcutaneous spinal direct current stimulation. Group 2 received on-line anodal transcranial direct current stimulation over the damaged cerebral hemisphere + cathodal transcutaneous spinal direct current stimulation. The primary outcome was the 6-minute walk test performed before, after, and at follow-up at 2 and 4 weeks post-treatment. The significant differences in the 6-minute walk test noted between groups at the first post-treatment evaluation (p = 0.041) were not maintained at either the 2-week (P = 0.650) or the 4-week (P = 0.545) follow-up evaluations. Our preliminary findings support the hypothesis that cathodal transcranial direct current stimulation over the contralesional

  6. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Systems Analysis of Human Visuo-Myoelectric Control Facilitated by Anodal Transcranial Direct Current Stimulation in Healthy Humans

    Directory of Open Access Journals (Sweden)

    Vinh Kha

    2018-04-01

    Full Text Available Induction of neuroplasticity by transcranial direct current stimulation (tDCS applied to the primary motor cortex facilitates motor learning of the upper extremities in healthy humans. The impact of tDCS on lower limb functions has not been studied extensively so far. In this study, we applied a system identification approach to investigate the impact of anodal transcranial direct current stimulation of the leg area of the motor cortex via the human visuo-myoelectric controller. The visuo-myoelectric reaching task (VMT involves ballistic muscle contraction after a visual cue. We applied a black box approach using a linear ARX (Auto-regressive with eXogenous input model for a visuomotor myoelectric reaching task. We found that a 20th order finite impulse response (FIR model captured the TARGET (single input—CURSOR (single output dynamics during a VMT. The 20th order FIR model was investigated based on gain/phase margin analysis, which showed a significant (p < 0.01 effect of anodal tDCS on the gain margin of the VMT system. Also, response latency and the corticomuscular coherence (CMC time delay were affected (p < 0.05 by anodal tDCS when compared to sham tDCS. Furthermore, gray box simulation results from a Simplified Spinal-Like Controller (SSLC model demonstrated that the input-output function for motor evoked potentials (MEP played an essential role in increasing muscle activation levels and response time improvement post-tDCS when compared to pre-tDCS baseline performance. This computational approach can be used to simulate the behavior of the neuromuscular controller during VMT to elucidate the effects of adjuvant treatment with tDCS.

  8. LiveWire interactive boundary extraction algorithm based on Haar wavelet transform and control point set direction search

    Science.gov (United States)

    Cheng, Jun; Zhang, Jun; Tian, Jinwen

    2015-12-01

    Based on deep analysis of the LiveWire interactive boundary extraction algorithm, a new algorithm focusing on improving the speed of LiveWire algorithm is proposed in this paper. Firstly, the Haar wavelet transform is carried on the input image, and the boundary is extracted on the low resolution image obtained by the wavelet transform of the input image. Secondly, calculating LiveWire shortest path is based on the control point set direction search by utilizing the spatial relationship between the two control points users provide in real time. Thirdly, the search order of the adjacent points of the starting node is set in advance. An ordinary queue instead of a priority queue is taken as the storage pool of the points when optimizing their shortest path value, thus reducing the complexity of the algorithm from O[n2] to O[n]. Finally, A region iterative backward projection method based on neighborhood pixel polling has been used to convert dual-pixel boundary of the reconstructed image to single-pixel boundary after Haar wavelet inverse transform. The algorithm proposed in this paper combines the advantage of the Haar wavelet transform and the advantage of the optimal path searching method based on control point set direction search. The former has fast speed of image decomposition and reconstruction and is more consistent with the texture features of the image and the latter can reduce the time complexity of the original algorithm. So that the algorithm can improve the speed in interactive boundary extraction as well as reflect the boundary information of the image more comprehensively. All methods mentioned above have a big role in improving the execution efficiency and the robustness of the algorithm.

  9. 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.

  10. Preliminary study on the control of direct injection diesel engine for better fuel flexibility and emissions control. Pt. 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Egnell, R.; Kassem, N.; Bohlin, T.

    1985-01-01

    This report summarizes the results of a preliminary study on turbocharged direct injection diesel engines. Part I reviews the qualitative dynamic aspects of turbocharged diesel engine and the factors that affect its transient behaviour. It gives a brief account of the model structure and the interrelationships between the different components of the model as well as the different types of engine models and the methods of simulation. The transient response of a turbocharged engine under changing load, speed, and ambient conditions are discussed. Methods to improve the transient response, thus reducing fuel consumption and smoke emissions are briefly reviewed. Finally, both conventional and advanced control strategies are discussed with emphasis on the control of fuel injection (Delta-control), injection time (Alfa-control), and exhaust gas recirculation (EGR-control). Part II (in Swedish) consists of a literature survey on hardware components such as sensors, actuators, and injection systems that are, or expect to be, available with reasonable commercial costs. The objective of this survey is to provide the grounds on which to decide if these components satisfy the requirements of electronic control systems. Part III (in Swedish) discusses the transient response measurements obtained from two sets of experiments conducted on a six-cylinder motor working under varying conditions of load and speed. The objective of the first set of experiments was to quantify the difference in ignition delay between the transient and steady state operating conditions. The second set of experiments were aimed to provide a basis on which the engine efficiency obtained under transient conditions can be compared to that obtained from a single-cylinder motor working under steady state conditions.

  11. Tempering Proactive Cognitive Control by Transcranial Direct Current Stimulation of the Right (but Not the Left Lateral Prefrontal Cortex

    Directory of Open Access Journals (Sweden)

    Carlos J. Gómez-Ariza

    2017-05-01

    Full Text Available Behavioral and neuroimaging data support the distinction of two different modes of cognitive control: proactive, which involves the active and sustained maintenance of task-relevant information to bias behavior in accordance with internal goals; and reactive, which entails the detection and resolution of interference at the time it occurs. Both control modes may be flexibly deployed depending on a variety of conditions (i.e., age, brain alterations, motivational factors, prior experience. Critically, and in line with specific predictions derived from the dual mechanisms of control account (Braver, 2012, findings from neuroimaging studies indicate that the same lateral prefrontal regions (i.e., left dorsolateral cortex and right inferior frontal junction may implement different control modes on the basis of temporal dynamics of activity, which would be modulated in response to external or internal conditions. In the present study, we aimed to explore whether transcraneal direct current stimulation over either the left dorsolateral prefrontal cortex or the right inferior frontal junction would differentially modulate performance on the AX-CPT, a well-validated task that provides sensitive and reliable behavioral indices of proactive/reactive control. The study comprised six conditions of real stimulation [3 (site: left dorsolateral, right dorsolateral and right inferior frontal junction × 2 (polarity: anodal and cathodal], and one sham condition. The reference electrode was always placed extracephalically. Performance on the AX-CPT was assessed through two blocks of trials. The first block took place while stimulation was being delivered, whereas the second block was administered after stimulation completion. The results indicate that both offline cathodal stimulation of the right dorsolateral prefrontal cortex and online anodal stimulation of the right inferior frontal junction led participants to be much less proactive, with such a dissociation

  12. Direct Digital Control Study.

    Science.gov (United States)

    1985-02-01

    Deck - Cold Deck Reset Reheat Coil Reset Steam Boiler Optimization [lot Water Outside Air Reset Chiller Optimization Chiller Water Temperature Reset...with programming techniques for each type of installed DDC in order to effect changes in operating setpoints and application programs. *Communication...can be changed without recailbration of instrumentation devices. Changes to the application software, operating setpoints and parameters require the

  13. Overview of condition monitoring and operation control of electric power conversion systems in direct-drive wind turbines under faults

    Science.gov (United States)

    Huang, Shoudao; Wu, Xuan; Liu, Xiao; Gao, Jian; He, Yunze

    2017-09-01

    Electric power conversion system (EPCS), which consists of a generator and power converter, is one of the most important subsystems in a direct-drive wind turbine (DD-WT). However, this component accounts for the most failures (approximately 60% of the total number) in the entire DD-WT system according to statistical data. To improve the reliability of EPCSs and reduce the operation and maintenance cost of DD-WTs, numerous researchers have studied condition monitoring (CM) and fault diagnostics (FD). Numerous CM and FD techniques, which have respective advantages and disadvantages, have emerged. This paper provides an overview of the CM, FD, and operation control of EPCSs in DD-WTs under faults. After introducing the functional principle and structure of EPCS, this survey discusses the common failures in wind generators and power converters; briefly reviewed CM and FD methods and operation control of these generators and power converters under faults; and discussed the grid voltage faults related to EPCSs in DD-WTs. These theories and their related technical concepts are systematically discussed. Finally, predicted development trends are presented. The paper provides a valuable reference for developing service quality evaluation methods and fault operation control systems to achieve high-performance and high-intelligence DD-WTs.

  14. 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.

  15. Direct and indirect controls on organic matter decomposition in four coastal wetland communities along a landscape salinity gradient

    Science.gov (United States)

    Stagg, Camille L.; Baustian, Melissa M.; Perry, Carey L.; Carruthers, Tim J.B.; Hall, Courtney T.

    2018-01-01

    Coastal wetlands store more carbon than most ecosystems globally. As sea level rises, changes in flooding and salinity will potentially impact ecological functions, such as organic matter decomposition, that influence carbon storage. However, little is known about the mechanisms that control organic matter loss in coastal wetlands at the landscape scale. As sea level rises, how will the shift from fresh to salt-tolerant plant communities impact organic matter decomposition? Do long-term, plant-mediated, effects of sea-level rise differ from direct effects of elevated salinity and flooding?We identified internal and external factors that regulated indirect and direct pathways of sea-level rise impacts, respectively, along a landscape-scale salinity gradient that incorporated changes in wetland type (fresh, oligohaline, mesohaline and polyhaline marshes). We found that indirect and direct impacts of sea-level rise had opposing effects on organic matter decomposition.Salinity had an indirect effect on litter decomposition that was mediated through litter quality. Despite significant variation in environmental conditions along the landscape gradient, the best predictors of above- and below-ground litter decomposition were internal drivers, initial litter nitrogen content and initial litter lignin content respectively. Litter decay constants were greatest in the oligohaline marsh and declined with increasing salinity, and the fraction of litter remaining (asymptote) was greatest in the mesohaline marsh. In contrast, direct effects of salinity and flooding were positive. External drivers, salinity and flooding, stimulated cellulytic activity, which was highest in the polyhaline marsh.Synthesis. Our results indicate that as sea level rises, initial direct effects of salinity will stimulate decay of labile carbon, but over time as plant communities shift from fresh to polyhaline marsh, litter decay will decline, yielding greater potential for long-term carbon storage

  16. Nuclear electronic equipment for control and monitoring boards. Specifications and test methods of direct current period meters

    International Nuclear Information System (INIS)

    Roquefort, Henri; Chapelot; Ramard; Tardif; Tournier; Vaux

    1973-11-01

    After a few words of introduction, mention of the main notations used and the definition of certain terms, the field of application of the document is outlined and a list of references given. The main specifications of electronic 'direct current period meter' subassemblies for the monitoring, control and safety of nuclear reactors are then defined and the corresponding test methods described. The apparatus measures on a logarithmic scale the neutron fluence rate of a reactor by means of an ionisation chamber and supplies 'period' data relative to the fluence rate variation in time. The specifications and test methods are given for the different components: logarithmic amplifier, time derivative unit, threshold releases, high tension supply for ionisation chamber, auxiliary circuits and finally the complete period meter. (author) [fr

  17. Dataset of acute repeated sessions of bifrontal transcranial direct current stimulation for treatment of intractable tinnitus: A randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Ali Yadollahpour

    2017-12-01

    Full Text Available Transcranial direct current stimulation (tDCS has reportedly shown promising therapeutic effects for tinnitus (Forogh et al., 2016; Joos et al., 2014 [1,2]. Studies are ongoing to determine optimum treatment protocol and the site of stimulation. Findings of the early studies are heterogeneous and most studies have focused on single session tDCS and short follow-up periods. There is no study on repeated sessions of tDCS with long term follow-up. This study presents the results of a randomized clinical trial investigating the therapeutic effects of acute multi-session tDCS over dorsolateral prefrontal cortex (DLPFC on tinnitus symptoms and comorbid depression and anxiety in patients with chronic intractable tinnitus. The dataset includes the demographic information, audiometric assessments, tinnitus specific characteristics, and the response variables of the study. The response variables included the scores of tinnitus handicap inventory (THI, tinnitus loudness and tinnitus related distress based on 0–10 numerical visual analogue scale (VAS scores, beck depression inventory (BDI-II and beck anxiety inventory (BAI scores. The dataset included the scores of THI pre and immediately post intervention, and at one month follow-up; the tinnitus loudness and distress scores prior to intervention, and immediately, one hour, one week, and at one month after the last stimulation session. In addition, the BDI-II, and BAI scores pre and post intervention are included. The data of the real (n=25 and sham tDCS (n=17 groups are reported. The main manuscript of this dataset is 'Acute repeated sessions of bifrontal transcranial direct current stimulation for treatment of intractable tinnitus: a randomized controlled trial' (Bayat et al., submitted for publication [3]. Keywords: Transcranial direct current stimulation, Acute stimulations, Tinnitus, Depression, Anxiety, DLPFC

  18. 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 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.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 services more frequently than those in

  19. Evaluation of an online interactive Diabetes Needs Assessment Tool (DNAT versus online self-directed learning: a randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Kellner Thomas

    2011-06-01

    Full Text Available Abstract Background Methods for the dissemination, understanding and implementation of clinical guidelines need to be examined for their effectiveness to help doctors integrate guidelines into practice. The objective of this randomised controlled trial was to evaluate the effectiveness of an interactive online Diabetes Needs Assessment Tool (DNAT (which constructs an e-learning curriculum based on individually identified knowledge gaps, compared with self-directed e-learning of diabetes guidelines. Methods Health professionals were randomised to a 4-month learning period and either given access to diabetes learning modules alone (control group or DNAT plus learning modules (intervention group. Participants completed knowledge tests before and after learning (primary outcome, and surveys to assess the acceptability of the learning and changes to clinical practice (secondary outcomes. Results Sixty four percent (677/1054 of participants completed both knowledge tests. The proportion of nurses (5.4% was too small for meaningful analysis so they were excluded. For the 650 doctors completing both tests, mean (SD knowledge scores increased from 47.4% (12.6 to 66.8% (11.5 [intervention group (n = 321, 64%] and 47.3% (12.9 to 67.8% (10.8 [control group (n = 329, 66%], (ANCOVA p = 0.186. Both groups were satisfied with the usability and usefulness of the learning materials. Seventy seven percent (218/284 of the intervention group reported combining the DNAT with the recommended reading materials was "very useful"/"useful". The majority in both groups (184/287, 64.1% intervention group and 206/299, 68.9% control group [95% CI for the difference (-2.8 to 12.4] reported integrating the learning into their clinical practice. Conclusions Both groups experienced a similar and significant improvement in knowledge. The learning materials were acceptable and participants incorporated the acquired knowledge into practice. Trial registration ISRCTN: ISRCTN67215088

  20. Anodal transcranial direct current stimulation of the left dorsolateral prefrontal cortex enhances emotion recognition in depressed patients and controls.

    Science.gov (United States)

    Brennan, Sean; McLoughlin, Declan M; O'Connell, Redmond; Bogue, John; O'Connor, Stephanie; McHugh, Caroline; Glennon, Mark

    2017-05-01

    Transcranial direct current stimulation (tDCS) can enhance a range of neuropsychological functions but its efficacy in addressing clinically significant emotion recognition deficits associated with depression is largely untested. A randomized crossover placebo controlled study was used to investigate the effects of tDCS over the left dorsolateral prefrontal cortex (L-DLPFC) on a range of neuropsychological variables associated with depression as well as neural activity in the associated brain region. A series of computerized tests was administered to clinical (n = 17) and control groups (n = 20) during sham and anodal (1.5 mA) stimulation. Anodal tDCS led to a significant main effect for overall emotion recognition (p = .02), with a significant improvement in the control group (p = .04). Recognition of disgust was significantly greater in the clinical group (p = .01). Recognition of anger was significantly improved for the clinical group (p = .04) during anodal stimulation. Differences between groups for each of the six emotions at varying levels of expression found that at 40% during anodal stimulation, happy recognition significantly improved for the clinical group (p = .01). Anger recognition at 80% during anodal stimulation significantly improved for the clinical group (p = .02). These improvements were observed in the absence of any change in psychomotor speed or trail making ability during anodal stimulation. Working memory significantly improved during anodal stimulation for the clinical group but not for controls (p = .03). The tentative findings of this study indicate that tDCS can have a neuromodulatory effect on a range of neuropsychological variables. However, it is clear that there was a wide variation in responses to tDCS and that individual difference and different approaches to testing and stimulation have a significant impact on final outcomes. Nonetheless, tDCS remains a promising tool for future neuropsychological research.

  1. Tratamiento acortado estrictamente supervisado para tuberculosis pulmonar Shortened directly observed treatment applied to the tuberculosis control program

    Directory of Open Access Journals (Sweden)

    Guadalupe del Carmen Alvarez-Gordillo

    1998-05-01

    Full Text Available Objetivo. Evaluar la posibilidad de aplicar el tratamiento acortado estrictamente supervisado (TAES en el Programa de Control de la Tuberculosis en Chiapas, México. Material y métodos. Se evaluó la eficacia y la eficiencia del tratamiento en una cohorte de pacientes con tuberculosis pulmonar confirmada por baciloscopía, que ingresaron a tratamiento con esquemas de autoadministración semisupervisión y estricta supervisión, de enero a junio de 1996. Resultados. La eficacia fue de 90.9. 97.7 y 100% para los esquemas de tratamiento autoadministrado, semisupervisado y TAES, respectivamente, mientras que la eficiencia fue de 68.1. 77.6 y 88.5% en el mismo orden. Conclusiones. Para la salud pública el TAES demostró ser la actividad más importante en el control de la tuberculosis, al elevar las tasas de curación y disminuir, por lo tanto, las fuentes de transmisión de la enfermedad.Objective. To evaluate the usefulness of the Shortened Directly Observed Treatment (DOT, S applied to the Tuberculosis Control Program in Chiapas, Mexico. Material and methods. The efficacy and efficiency of treatment was evaluated in a cohort of pulmonary tuberculosis patients confirmed by baciloscopy, who were subjected to treatment under one of three different regimes, self-administered. supervised and DOT,S from January to June 1996. Results. Efficacy was 90.9%, 97.7% and 100% for self-administered, supervised and DOT,S treatment, respectively. Efficiency was 68.1%, 77.6% and 88.5% in the same order Conclusions. For public health ends, the DOT,S proved to be the most efficient in the control of tuberculosis. since healing rates were increased and this reduces sources of disease transmission.

  2. Direction of glucose fermentation towards hydrogen or ethanol production through on-line pH control

    Energy Technology Data Exchange (ETDEWEB)

    Karadag, Dogan; Puhakka, Jaakko A. [Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere (Finland)

    2010-10-15

    The present study investigated the production of hydrogen (H{sub 2}) and ethanol from glucose in an Anaerobic Continuous Stirred Tank Reactor (ACSTR). Effects of hydraulic retention time (HRT) and pH on the preference of producing H{sub 2} and/or ethanol and other soluble metabolic products in an open anaerobic enriched culture were studied. Production rates of H{sub 2} and ethanol increased with the increase of biomass concentration. Open anaerobic fermentation was directed and managed through on-line pH control for the production of H{sub 2} or ethanol. Hydrogen was produced by ethanol and acetate-butyrate type fermentations. pH has strong effect on the H{sub 2} or ethanol production by changing fermentation pathways. ACSTR produced mainly ethanol at over pH 5.5 whereas highest H{sub 2} production was obtained at pH 5.0. pH 4.9 favored the lactate production and accumulation of lactate inhibited the biomass concentration in the reactor and the production of H{sub 2} and ethanol. The microbial community structure quickly responded to pH changes and the Clostridia dominated in ACSTR during the study. H{sub 2} production was maintained mainly by Clostridium butyricum whereas in the presence of Bacillus coagulans glucose oxidation was directed to lactate production. (author)

  3. Hemispheric differences in the voluntary control of spatial attention: direct evidence for a right-hemispheric dominance within frontal cortex.

    Science.gov (United States)

    Duecker, Felix; Formisano, Elia; Sack, Alexander T

    2013-08-01

    Lesion studies in neglect patients have inspired two competing models of spatial attention control, namely, Heilman's "hemispatial" theory and Kinsbourne's "opponent processor" model. Both assume a functional asymmetry between the two hemispheres but propose very different mechanisms. Neuroimaging studies have identified a bilateral dorsal frontoparietal network underlying voluntary shifts of spatial attention. However, lateralization of attentional processes within this network has not been consistently reported. In the current study, we aimed to provide direct evidence concerning the functional asymmetry of the right and left FEF during voluntary shifts of spatial attention. To this end, we applied fMRI-guided neuronavigation to disrupt individual FEF activation foci with a longer-lasting inhibitory patterned TMS protocol followed by a spatial cueing task. Our results indicate that right FEF stimulation impaired the ability of shifting spatial attention toward both hemifields, whereas the effects of left FEF stimulation were limited to the contralateral hemifield. These results provide strong direct evidence for right-hemispheric dominance in spatial attention within frontal cortex supporting Heilman's "hemispatial" theory. This complements previous TMS studies that generally conform to Kinsbourne's "opponent processor" model after disruption of parietal cortex, and we therefore propose that both theories are not mutually exclusive.

  4. 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.

  5. El control de constitucionalidad de la ‘legislación popular’ (Constitutional Review of Direct Legislation

    Directory of Open Access Journals (Sweden)

    Daniel López Rubio

    2017-12-01

    Full Text Available El control de constitucionalidad de las leyes implica lo que Cappelletti denominó “un formidable problema”: jueces sin legitimidad democrática directa controlan normas creadas por los representantes electos de los ciudadanos. El mecanismo produce una importante tensión entre la racionalidad jurídica y los principios puramente democráticos. El presente trabajo estudia cómo esta tensión llega a cotas máximas cuando la norma legal a enjuiciar ha sido aprobada por los ciudadanos a través de referéndum y analiza cómo se ha desarrollado este tipo de control en Estados Unidos, Francia y España. A la luz de los casos estudiados, se sugiere la necesidad de que la jurisdicción constitucional actúe en determinadas circunstancias con especial deferencia cuando se enfrente a productos normativos aprobados de modo directo por la ciudadanía.Judicial review of legislation implies what Cappelletti called “a mighty problem”: judges without direct democratic legitimacy review legal regulations created by elected representatives. The mechanism generates great tension between legal rationality and democratic principles. This paper analyzes how this tension reaches a high point when the regulation at issue has been approved by the people through a referendum and examines how this review process has developed in the United States, France and Spain. In the light of the analyzed cases, it is suggested that the constitutional jurisdiction act, under certain circumstances, with special deference when it faces legal rules directly approved by the people.DOWNLOAD THIS PAPER FROM SSRN: https://ssrn.com/abstract=3033020

  6. Definition and implementation of internal model control laws for a direct injection engine; Definition et mise en oeuvre de lois de commande a modele interne pour un moteur thermique a injection directe d'essence

    Energy Technology Data Exchange (ETDEWEB)

    Grousson, F.

    2000-10-03

    This study has been achieved in order to improve the direct injection engine control, by using internal model control strategies. Its aim is to optimise the engine performance and to decrease the polluting emissions through a better dynamic control. The use of internal model controls brings robustness in order to face the engine parameter disparity and allows great improvements in the control calibration thanks to a shorter tuning time. The first part gives the outlines of thermic engine operating and focuses on modeling with the final control in view. The second part tackles the implementation of regulation algorithms. Firstly, the air path control uses the state feedback linearization mixed with the predictive control. Secondly, the torque control of the driver's requests is performed with a static inversion using the Jacobian matrix. Finally, a simplified predictive control makes it possible to solve idle speed regulation problems. The last part is devoted to real time and fast proto-typing tests. The main simulation results have been validated through experimental tests on a direct injection car. (author)

  7. 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.

  8. 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...

  9. 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. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  10. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. 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.

  12. SCAN- a maintenance-free flowrate meter with direct digital read-out for computerised control applications in radiochemical plants

    Energy Technology Data Exchange (ETDEWEB)

    Shah, B V; Siddiqui, I A; Theyyunni, T K [Process Engineering and Systems Division, Bhabha Atomic Research Centre, Mumbai (India)

    1994-06-01

    In radiochemical plants, the choice of flowrate sensor is subject to stringent requirements of fail-safe design and freedom from maintenance. The SCAN remote digital direct indicating flowrate meter described in this paper was developed to meet the requirements of flowrate and transmitting it to the control room, and to a computerised control system. SCAN is designed on the principle that flowrate through an orifice is a function of the head of liquid acting upon it. SCAN consists of a small chamber which receives the flow, and discharges it through an orifice located in bottom. The level of liquid in the pot represents the flowrate of the input stream. SCAN has been developed into an accurate, rugged and practical device by refinements in the design of internals, and by introducing a special end-section which makes the calibration insensitive to location. An important feature of SCAN is that it is passive, maintenance free, fail-safe device and contains no moving parts. There is no liquid hold up in the SCAN when idle, which is a desirable feature for the radiochemical plant environment. (author). 3 figs., 2 tabs.

  13. Effects of the addition of transcranial direct current stimulation to virtual reality therapy after stroke: a pilot randomized controlled trial.

    Science.gov (United States)

    Viana, R T; Laurentino, G E C; Souza, R J P; Fonseca, J B; Silva Filho, E M; Dias, S N; Teixeira-Salmela, L F; Monte-Silva, K K

    2014-01-01

    Upper limb (UL) impairment is the most common disabling deficit following a stroke. Previous studies have suggested that transcranial direct current stimulation (tDCS) enhances the effect of conventional therapies. This pilot double-blind randomized control trial aimed to determine whether or not tDCS, combined with Wii virtual reality therapy (VRT), would be superior to Wii therapy alone in improving upper limb function and quality of life in chronic stroke individuals. Twenty participants were randomly assigned either to an experimental group that received VRT and tDCS, or a control group that received VRT and sham tDCS. The therapy was delivered over 15 sessions with 13 minutes of active or sham anodal tDCS, and one hour of virtual reality therapy. The outcomes included were determined using the Fugl-Meyer scale, the Wolf motor function test, the modified Ashworth scale (MAS), grip strength, and the stroke specific quality of life scale (SSQOL). Minimal clinically important differences (MCID) were observed when assessing outcome data. Both groups demonstrated gains in all evaluated areas, except for the SSQOL-UL domain. Differences between groups were only observed in wrist spasticity levels in the experimental group, where more than 50% of the participants achieved the MCID. These findings support that tDCS, combined with VRT therapy, should be investigated and clarified further.

  14. Analysis and experimental evaluation of shunt active power filter for power quality improvement based on predictive direct power control.

    Science.gov (United States)

    Aissa, Oualid; Moulahoum, Samir; Colak, Ilhami; Babes, Badreddine; Kabache, Nadir

    2017-10-12

    This paper discusses the use of the concept of classical and predictive direct power control for shunt active power filter function. These strategies are used to improve the active power filter performance by compensation of the reactive power and the elimination of the harmonic currents drawn by non-linear loads. A theoretical analysis followed by a simulation using MATLAB/Simulink software for the studied techniques has been established. Moreover, two test benches have been carried out using the dSPACE card 1104 for the classic and predictive DPC control to evaluate the studied methods in real time. Obtained results are presented and compared in this paper to confirm the superiority of the predictive technique. To overcome the pollution problems caused by the consumption of fossil fuels, renewable energies are the alternatives recommended to ensure green energy. In the same context, the tested predictive filter can easily be supplied by a renewable energy source that will give its impact to enhance the power quality.

  15. Deemed Savings Estimates for Legacy Air Conditioning and WaterHeating Direct Load Control Programs in PJM Region

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Charles

    2007-03-01

    During 2005 and 2006, the PJM Interconnection (PJM) Load Analysis Subcommittee (LAS) examined ways to reduce the costs and improve the effectiveness of its existing measurement and verification (M&V) protocols for Direct Load Control (DLC) programs. The current M&V protocol requires that a PURPA-compliant Load Research study be conducted every five years for each Load-Serving Entity (LSE). The current M&V protocol is expensive to implement and administer particularly for mature load control programs, some of which are marginally cost-effective. There was growing evidence that some LSEs were mothballing or dropping their DLC programs in lieu of incurring the expense associated with the M&V. This project had several objectives: (1) examine the potential for developing deemed savings estimates acceptable to PJM for legacy air conditioning and water heating DLC programs, and (2) explore the development of a collaborative, regional, consensus-based approach for conducting monitoring and verification of load reductions for emerging load management technologies for customers that do not have interval metering capability.

  16. 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 et les reponses theoriques ont

  17. 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

  18. 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.

  19. Goal-directed control with cortical units that are gated by both top-down feedback and oscillatory coherence

    Science.gov (United States)

    Kerr, Robert R.; Grayden, David B.; Thomas, Doreen A.; Gilson, Matthieu; Burkitt, Anthony N.

    2014-01-01

    The brain is able to flexibly select behaviors that adapt to both its environment and its present goals. This cognitive control is understood to occur within the hierarchy of the cortex and relies strongly on the prefrontal and premotor cortices, which sit at the top of this hierarchy. Pyramidal neurons, the principal neurons in the cortex, have been observed to exhibit much stronger responses when they receive inputs at their soma/basal dendrites that are coincident with inputs at their apical dendrites. This corresponds to inputs from both lower-order regions (feedforward) and higher-order regions (feedback), respectively. In addition to this, coherence between oscillations, such as gamma oscillations, in different neuronal groups has been proposed to modulate and route communication in the brain. In this paper, we develop a simple, but novel, neural mass model in which cortical units (or ensembles) exhibit gamma oscillations when they receive coherent oscillatory inputs from both feedforward and feedback connections. By forming these units into circuits that can perform logic operations, we identify the different ways in which operations can be initiated and manipulated by top-down feedback. We demonstrate that more sophisticated and flexible top-down control is possible when the gain of units is modulated by not only top-down feedback but by coherence between the activities of the oscillating units. With these types of units, it is possible to not only add units to, or remove units from, a higher-level unit's logic operation using top-down feedback, but also to modify the type of role that a unit plays in the operation. Finally, we explore how different network properties affect top-down control and processing in large networks. Based on this, we make predictions about the likely connectivities between certain brain regions that have been experimentally observed to be involved in goal-directed behavior and top-down attention. PMID:25152715

  20. Goal-directed control with cortical units that are gated by both top-down feedback and oscillatory coherence

    Directory of Open Access Journals (Sweden)

    Robert R. Kerr

    2014-08-01

    Full Text Available The brain is able to flexibly select behaviors that adapt to both its environment and its present goals. This cognitive control is understood to occur within the hierarchy of the cortex and relies strongly on the prefrontal and premotor cortices, which sit at the top of this hierarchy. Pyramidal neurons, the principal neurons in the cortex, have been observed to exhibit much stronger responses when they receive inputs at their soma/basal dendrites that are coincident with inputs at their apical dendrites. This corresponds to inputs from both lower-order regions (feedforward and higher-order regions (feedback, respectively. In addition to this, coherence between oscillations, such as gamma oscillations, in different neuronal groups has been proposed to modulate and route communication in the brain. In this paper, we develop a simple, but novel, neural mass model in which cortical units (or ensembles exhibit gamma oscillations when they receive coherent oscillatory inputs from both feedforward and feedback connections. By forming these units into circuits that can perform logic operations, we identify the different ways in which operations can be initiated and manipulated by top-down feedback. We demonstrate that more sophisticated and flexible top-down control is possible when the gain of units is modulated by not only top-down feedback but by coherence between the activities of the oscillating units. With these types of units, it is possible to not only add units to, or remove units from, a higher-level unit's logic operation using top-down feedback, but also to modify the type of role that a unit plays in the operation. Finally, we explore how different network properties affect top-down control and processing in large networks. Based on this, we make predictions about the likely connectivities between certain brain regions that have been experimentally observed to be involved in goal-directed behavior and top-down attention.