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Sample records for controls phase variable

  1. Evidence for a time-invariant phase variable in human ankle control.

    Directory of Open Access Journals (Sweden)

    Robert D Gregg

    Full Text Available Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms. In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control.

  2. Designing stable finite state machine behaviors using phase plane analysis and variable structure control

    Energy Technology Data Exchange (ETDEWEB)

    Feddema, J.T.; Robinett, R.D.; Driessen, B.J.

    1998-03-10

    This paper discusses how phase plane analysis can be used to describe the overall behavior of single and multiple autonomous robotic vehicles with finite state machine rules. The importance of this result is that one can begin to design provably asymptotically stable group behaviors from a set of simple control laws and appropriate switching points with decentralized variable structure control. The ability to prove asymptotically stable group behavior is especially important for applications such as locating military targets or land mines.

  3. Demonstration of a Controlled-Phase Gate for Continuous-Variable One-Way Quantum Computation

    CERN Document Server

    Ukai, Ryuji; Yoshikawa, Jun-ichi; van Loock, Peter; Furusawa, Akira

    2011-01-01

    We experimentally demonstrate a controlled-phase gate for continuous variables in a fully measurement-based fashion. In our scheme, the two independent input states of the gate, encoded in two optical modes, are teleported into a four-mode Gaussian cluster state. As a result, one of the entanglement links present in the initial cluster state appears in the two unmeasured output modes as the corresponding entangling gate acting on the input states. The genuine quantum character of this gate becomes manifest and is verified through the presence of entanglement at the output for a product two-mode coherent input state. By combining our controlled-phase gate with the recently reported module for universal single-mode Gaussian operations [R. Ukai et al., Phys. Rev. Lett. 106, 240504 (2011)], it is possible to implement universal Gaussian operations on arbitrary multi-mode quantum optical states in form of a fully measurement-based one-way quantum computation.

  4. Development of a variable frequency power electronics inverter to control the speed of a three-phase induction motor

    OpenAIRE

    Neves, Pedro; Afonso, João L.

    2006-01-01

    This work presents the development and implementation of a variable frequency Power Electronics inverter to drive a three-phase induction motor. The inverter allows a user to control the speed and torque developed by the motor, as well as its rotating direction. The inverter’s digital controller was implemented with a microcontroller. The inverter is fed from a rectifier with capacitor filter, which is connected to single-phase, 50 Hz power mains.

  5. Independently variable phase and stroke control for a double acting Stirling engine

    Science.gov (United States)

    Berchowitz, David M.

    1983-01-01

    A phase and stroke control apparatus for the pistons of a Stirling engine includes a ring on the end of each piston rod in which a pair of eccentrics is arranged in series, torque transmitting relationship. The outer eccentric is rotatably mounted in the ring and is rotated by the orbiting ring; the inner eccentric is mounted on an output shaft. The two eccentrics are mounted for rotation together within the ring during normal operation. A device is provided for rotating one eccentric with respect to another to change the effective eccentricity of the pair of eccentrics. A separately controlled phase adjustment is provided to null the phase change introduced by the change in the orientation of the outer eccentric, and also to enable the phase of the pistons to be changed independently of the stroke change.

  6. Variable speed controller

    Science.gov (United States)

    Estes, Christa; Spiggle, Charles; Swift, Shannon; Vangeffen, Stephen; Younger, Frank

    1992-01-01

    This report details a new design for a variable speed controller which can be used to operate lunar machinery without the astronaut using his or her upper body. In order to demonstrate the design, a treadle for an industrial sewing machine was redesigned to be used by a standing operator. Since the invention of an electrically powered sewing machine, the operator has been seated. Today, companies are switching from sit down to stand up operation involving modular stations. The old treadle worked well with a sitting operator, but problems have been found when trying to use the same treadle with a standing operator. Emphasis is placed on the ease of use by the operator along with the ergonomics involved. Included with the design analysis are suggestions for possible uses for the speed controller in other applications.

  7. Unified phase variables of relative degree two for human locomotion.

    Science.gov (United States)

    Villarreal, Dario J; Gregg, Robert D; Villarreal, Dario J; Gregg, Robert D; Gregg, Robert D; Villarreal, Dario J

    2016-08-01

    A starting point to achieve stable locomotion is synchronizing the leg joint kinematics during the gait cycle. Some biped robots parameterize a nonlinear controller (e.g., input-output feedback linearization) whose main objective is to track specific kinematic trajectories as a function of a single mechanical variable (i.e., a phase variable) in order to allow the robot to walk. A phase variable capable of parameterizing the entire gait cycle, the hip phase angle, has been used to control wearable robots and was recently shown to provide a robust representation of the phase of human gait. However, this unified phase variable relies on hip velocity, which is difficult to measure in real-time and prevents the use of derivative corrections in phase-based controllers for wearable robots. One derivative of this phase variable yields accelerations (i.e., the equations of motion), so the system is said to be relative degree-one. This means that there are states of the system that cannot be controlled. The goal of this paper is to offer relative degree-two alternatives to the hip phase angle and examine their robustness for parameterizing human gait.

  8. Cartas de control para monitorear variables multinomiales

    Directory of Open Access Journals (Sweden)

    Luz Marcela Restrepo-Tamayo

    2014-07-01

    Full Text Available Background: The control as a tool for monitoring the quality of a product, allows to study the stability of processes over time, contrasting two hypothesis, which states that the process is in stable condition and the other denies it. Its use has been massive for continuous variables but not for categorical variables, why it is imperative to design such tools for such variables. Objective: To propose two (2 control charts for variables multinomial processes based on the p-value test result for homogeneity of proportions using the chi square test for uniform processing variables and approximation Wilson - Hilferty for variables chi square. Methods: The performance of proposed charts via simulation is estimated considering a Phase II process and considering the first category increments of 2%, 4% and 6% in the control stage. Results: The multinomial control chart using Wilson-Hilferty approximation for variables chi square, from the transformation of value-p, has poor performance compared to the control charts using p-value processing and using chi-square p-value, as they have less ability to detect small changes. Conclusion: We propose two control charts to monitor multinomial variables and once studied via simulation, based on the average run length (ARL and the probability of rejecting the null hypothesis of equal proportions, we recommend the control chart using value-p, or equivalently, the control chart processing using chi square p-value.

  9. A Novel Choice Procedure of Magnetic Component Values for Phase Shifted Full Bridge Converters with a Variable Dead-Time Control Method

    Directory of Open Access Journals (Sweden)

    Lei Zhao

    2015-09-01

    Full Text Available Magnetic components are important parts of the phase shifted full bridge (PSFB converter. During the dead-time of switches located in the same leg, the converter can achieve zero-voltage-switching (ZVS by using the energies stored in magnetic components to discharge or charge the output capacitances of switches. Dead-time is usually calculated under a given set of pre-defined load condition which results in that the available energies are insufficient and ZVS capability is lost at light loads. In this paper, the PSFB converter is controlled by variable dead-time method and thus full advantage can be taken of the energies stored in magnetic components. Considering that dead-time has a great effect on ZVS, the relationship between available energies and magnetic component values is formulated by analyzing the equivalent circuits during dead-time intervals. Magnetic component values are chosen based on such relationship. The proposed choice procedure can make the available energies greater than the required energies for ZVS operation over a wide range of load conditions. Moreover, the burst mode control is adopted in order to reduce the standby power loss. Experimental results coincide with the theoretical analysis. The proposed method is a simple and practical solution to extend the ZVS range.

  10. Variable centroid control scheme over hypersonic tactical missile

    Institute of Scientific and Technical Information of China (English)

    Yl; Yan(易彦); ZHOU; Fengqi(周凤岐)

    2003-01-01

    This paper presents a brand-new tactical missile control scheme--variable centroid vector control according to the international highlight in the field of missile control and the research status of hypersonic missile control in China. Four critical problems related with the new control method are included: improving phase control in the spinning missile single-channel control; establishing variable centroid controlled spinning missile attitude dynamics equations; analyzing variable centroid control strategies and analyzing the stability of the controlled missile and implementing robust control. The achievements and results obtained are valuable and helpful to the theoretical explorations and engineering applications.

  11. Variable centroid control scheme over hypersonic tactical missile

    Science.gov (United States)

    Yi, Yan; Zhou, Fengqi

    2003-12-01

    This paper presents a brand-new tactical missile control scheme—variable centroid vector control according to the international highlight in the field of missile control and the research status of hypersonic missile control in China. Four critical problems related with the new control method are included: improving phase control in the spinning missile single-channel control; establishing variable centroid controlled spinning missile attitude dynamics equations; analyzing variable centroid control strategies and analyzing the stability of the controlled missile and implementing robust control. The achievements and results obtained are valuable and helpful to the theoretical explorations and engineering applications.

  12. Phase variable O antigen biosynthetic genes control expression of the major protective antigen and bacteriophage receptor in Vibrio cholerae O1.

    Directory of Open Access Journals (Sweden)

    Kimberley D Seed

    2012-09-01

    Full Text Available The Vibrio cholerae lipopolysaccharide O1 antigen is a major target of bacteriophages and the human immune system and is of critical importance for vaccine design. We used an O1-specific lytic bacteriophage as a tool to probe the capacity of V. cholerae to alter its O1 antigen and identified a novel mechanism by which this organism can modulate O antigen expression and exhibit intra-strain heterogeneity. We identified two phase variable genes required for O1 antigen biosynthesis, manA and wbeL. manA resides outside of the previously recognized O1 antigen biosynthetic locus, and encodes for a phosphomannose isomerase critical for the initial step in O1 antigen biosynthesis. We determined that manA and wbeL phase variants are attenuated for virulence, providing functional evidence to further support the critical role of the O1 antigen for infectivity. We provide the first report of phase variation modulating O1 antigen expression in V. cholerae, and show that the maintenance of these phase variable loci is an important means by which this facultative pathogen can generate the diverse subpopulations of cells needed for infecting the host intestinal tract and for escaping predation by an O1-specific phage.

  13. Three phase voltage model AC-AC frequency-variable inverter controlled by single-chip microcomputer%单片机控制的三相电压型交-交变频器

    Institute of Scientific and Technical Information of China (English)

    王建国

    2001-01-01

    介绍一种单片机控制的三相电压型交-交变频器,论述了交-交变频器的系统组成、控制方案及有关难点问题的解决%This paper introduces a kind of three phase voltage model AC-ACfrequency-variable inverter controlled by single-chip microcomputer control. Construction of the system ,controlling program and solution of some difficult problems are described

  14. Design of agricultural low-power single-phase variable frequency control system based on SPWM%基于SPWM对农用小功率单相变频控制系统的设计

    Institute of Scientific and Technical Information of China (English)

    胡灿; 陈超; 蒋建云; 孟祥营; 王旭峰

    2013-01-01

    For the problem that the agricultural low-power three-phase AC motor cannot be widely used because the three-phase power supply is not easy to get,one kind of three-phase AC variable frequency system which can output stepless regula-tion voltage amplitude was designed under the condition of agricultural 220 V single-phase AC power supply,through which the low-power three-phase AC motor can be widely used under the condition of agricultural single-phase power supply. The experi-mental results show that the controllable three-phase AC power can be output when 220 V AC power supply is input. The reaso-nable design of system hardware provides the technical support for the wide application of variable frequency control of agricu-ltural low-power supply.%  针对农用小功率三相交流电机不易获取三相电源而无法广泛应用的问题,设计了一种在农用220 V单相交流电源的情况下,可输出电压幅值可无级调控的三相交流变频系统,能够实现小功率三相交流电机在农用单相电源的情况下广泛地使用。实验结果表明:当输入220 V交流电源时,可输出三相可控的交流电源。系统硬件设计合理,为农用小功率电源的变频控制的广泛应用提供了技术支持。

  15. Phase control of excitable systems

    Energy Technology Data Exchange (ETDEWEB)

    Zambrano, S; Seoane, J M; Marino, I P; Sanjuan, M A F [Nonlinear Dynamics and Chaos Group, Departamento de Fisica, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain); Euzzor, S; Meucci, R; Arecchi, F T [CNR-Istituto Nazionale di Ottica Applicata, Largo E. Fermi, 6 50125 Firenze (Italy)], E-mail: samuel.zambrano@urjc.es, E-mail: jesus.seoane@urjc.es, E-mail: ines.perez@urjc.es

    2008-07-15

    Here we study how to control the dynamics of excitable systems by using the phase control technique. Excitable systems are relevant in neuronal dynamics and therefore this method might have important applications. We use the periodically driven FitzHugh-Nagumo (FHN) model, which displays both spiking and non-spiking behaviours in chaotic or periodic regimes. The phase control technique consists of applying a harmonic perturbation with a suitable phase {phi} that we adjust in search of different behaviours of the FHN dynamics. We compare our numerical results with experimental measurements performed on an electronic circuit and find good agreement between them. This method might be useful for a better understanding of excitable systems and different phenomena in neuronal dynamics.

  16. Adaptive fuzzy controllers based on variable universe

    Institute of Scientific and Technical Information of China (English)

    李洪兴

    1999-01-01

    Adaptive fuzzy controllers by means of variable universe are proposed based on interpolation forms of fuzzy control. First, monotonicity of control rules is defined, and it is proved that the monotonicity of interpolation functions of fuzzy control is equivalent to the monotonicity of control rules. This means that there is not any contradiction among the control rules under the condition for the control rules being monotonic. Then structure of the contraction-expansion factor is discussed. At last, three models of adaptive fuzzy control based on variable universe are given which are adaptive fuzzy control model with potential heredity, adaptive fuzzy control model with obvious heredity and adaptive fuzzy control model with successively obvious heredity.

  17. Extinction controlled adaptive phase-mask coronagraph

    CERN Document Server

    Bourget, P; Mawet, D; Haguenauer, P

    2012-01-01

    Context. Phase-mask coronagraphy is advantageous in terms of inner working angle and discovery space. It is however still plagued by drawbacks such as sensitivity to tip-tilt errors and chromatism. A nulling stellar coronagraph based on the adaptive phase-mask concept using polarization interferometry is presented in this paper. Aims. Our concept aims at dynamically and achromatically optimizing the nulling efficiency of the coronagraph, making it more immune to fast low-order aberrations (tip-tilt errors, focus, ...). Methods. We performed numerical simulations to demonstrate the value of the proposed method. The active control system will correct for the detrimental effects of image instabilities on the destructive interference. The mask adaptability both in size, phase and amplitude also compensates for manufacturing errors of the mask itself, and potentially for chromatic effects. Liquid-crystal properties are used to provide variable transmission of an annulus around the phase mask, but also to achieve t...

  18. Position Control of Synchronous Motor Drive by Modified Adaptive Two-phase Sliding Mode Controller

    Institute of Scientific and Technical Information of China (English)

    Mohamed Said Sayed Ahmed; Ping Zhang; Yun-Jie Wu

    2008-01-01

    A modified adaptive two-phase sliding mode controller for the synchronous motor drive that is highly robust to uncertain-ties and external disturbances is proposed in this paper. The proposed controller uses two-phase sliding mode control (SMC) where the 1st phase mainly controls the system in steady states and disturbed states-it is a smoothing phase. The 2nd phase is used mainly in the case of disturbed states. Also, it is an autotuning phase and uses a simple adaptive algorithm to tune the gain of conventional variable structure control (VSC). The modified controller is useful in position control of a permanent magnet synchronous drive.

  19. Vector Control of Three-Phase Induction Motor with Two Stator Phases Open-Circuit

    OpenAIRE

    Seyed Hesam Asgari; Mohammad Jannati; Tole Sutikno; Nik Rumzi Nik Idris

    2015-01-01

    Variable frequency drives are used to provide reliable dynamic systems and significant reduction in usage of energy and costs of the induction motors. Modeling and control of faulty or an unbalanced three-phase induction motor is obviously different from healthy three-phase induction motor. Using conventional vector control techniques such as Field-Oriented Control (FOC) for faulty three-phase induction motor, results in a significant torque and speed oscillation. This research presented a no...

  20. Gait variability and motor control in people with knee osteoarthritis

    DEFF Research Database (Denmark)

    Alkjaer, Tine; Raffalt, Peter C; Dalsgaard, Helle

    2015-01-01

    Knee osteoarthritis (OA) is a common disease that impairs walking ability and function. We compared the temporal gait variability and motor control in people with knee OA with healthy controls. The purpose was to test the hypothesis that the temporal gait variability would reflect a more...... fluctuation analysis. The motor control was assessed by the soleus (SO) Hoffmann (H)-reflex modulation and muscle co-activation during walking. The results showed no statistically significant mean group differences in any of the gait variability measures or muscle co-activation levels. The SO H......-reflex amplitude was significantly higher in the knee OA group around heel strike when compared with the controls. The mean group difference in the H-reflex in the initial part of the stance phase (control-knee OA) was -6.6% Mmax (95% CI: -10.4 to -2.7, p=0.041). The present OA group reported relatively small...

  1. 滑模变结构矢量控制在三相光伏并网系统中的应用%SLIDING MODE VARIABLE STRUCTURE VECTOR CONTROL OF THREE-PHASE GRID-CONNECTED PV POWER SYSTEM

    Institute of Scientific and Technical Information of China (English)

    李军红; 洪镇南

    2013-01-01

    研究三相单级光伏并网系统,建立并网逆变器在同步旋转d-q坐标系下的数学模型,提出一种新型的滑模变结构矢量控制方法.将并网电流分解为有功电流和无功电流,控制无功电流分量为零,实现单位功率因数并网;控制有功电流分量为MPPT算法给定的参考值,实现最大输出功率跟踪.组建实验样机,进行稳态和动态性能测试,实验结果表明所提出系统的可行性和控制策略的有效性.%The three-phase on-grid PV power generation system is studied,and mathematical model of three-phase on-grid inverter was established in synchronous rotating reference frame (d-q).A novel sliding mode variable structure vector control methods is put forward,which made the grid current into the active current and the reactive current.Unit power factor is achieved by controlling the reactive current component to be zero; and PV maximum power output was realized by controlling the active current component to be the reference value given by MPPT controller.A laboratory prototype is designed to perform static and dynamic experiments.Some experimental results verify that the proposed control strategy can improve the quality of grid current and supply power to grid with unity power factor.

  2. Remote Control Guidance Law Design Using Variable Structure Control

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A method of sliding mode variable structure control for the missile body being a time varying system is presented. A remote control guidance law is designed. The method has strong robustness to target's maneuver. To reduce the chattering phenomena, quasi-sliding mode variable structure control method is used. Simulation results show that the proposed method has small miss distance for any kind of maneuvering targets and requires small control energy.

  3. Numerical Simulation on CCOS Controllable Variable

    Institute of Scientific and Technical Information of China (English)

    CHENG Hao-bo; FENG Zhi-jing

    2003-01-01

    On the basis of Preston hypothesis,the motion relationship between tool and workpiece upon the tool's motion in planar model is analyzed.The effect on computer controlled optical surfacing (CCOS) caused by controllable variable is simulated except for the dwelling time,thus,some reference on theory is provided to optimize the former numerical control (NC) model,and fast manufacturing of large departure aspherics is realized.

  4. Phase control system for SSRF linac

    Institute of Scientific and Technical Information of China (English)

    YIN Chongxian; YU Luyang; LIU Dekang

    2008-01-01

    The design of phase control system in Shanghai Synchrotron Radiation Facility (SSRF) linac is presented in this paper. And digital phase detecting algorithm, the key for phase control system, is fully described. The testing results for phase control system in 100MeV linac are discussed in detail.

  5. A Variable Control Structure Controller for the Wing Rock Phenomenon

    OpenAIRE

    2016-01-01

    This paper presents the design of a variable structure controller for the model of the wing rock phenomenon of a delta wing aircraft. It is considered to be a continue study of the last two researches for the same phenomena "Feedback linearization [15] and back stepping controller [14] ". A control technique is proposed to stabilize the aircraft phenomena. The solution presented in this paper give a guarantee of asymptotic convergence to zero of all variables of the system. MATLAB...

  6. Adaptive Variable Bias Magnetic Bearing Control

    Science.gov (United States)

    Johnson, Dexter; Brown, Gerald V.; Inman, Daniel J.

    1998-01-01

    Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. With the existence of the bias current, even in no load conditions, there is always some power consumption. In aerospace applications, power consumption becomes an important concern. In response to this concern, an alternative magnetic bearing control method, called Adaptive Variable Bias Control (AVBC), has been developed and its performance examined. The AVBC operates primarily as a proportional-derivative controller with a relatively slow, bias current dependent, time-varying gain. The AVBC is shown to reduce electrical power loss, be nominally stable, and provide control performance similar to conventional bias control. Analytical, computer simulation, and experimental results are presented in this paper.

  7. 三相光伏并网系统的滑模变结构控制%Sliding mode variable structure controller for three-phase grid-connected photovoltaic systems

    Institute of Scientific and Technical Information of China (English)

    李军红; 洪镇南

    2012-01-01

    Anovel sliding mode variable structure controller based on voltage-oriented control is designed for three-phase photovoltaic (PV) grid system. The grid-connected current is decomposed into active and reactive components. In order to transfer maximum solar array energy into grid with a unity power factor, the reactive component is adjusted to be zero and the active component is controlled to follow the reference value, which is generated by MPPT controller. This method combines vector control technology with sliding mode control theory, which strengthens robustness of the system, accelerates the response speed and effectively improves the quality of the grid-connected current. A laboratory prototype is set up to perform static and dynamic experiments. Some oscilloscope test waveforms verify that the proposed control strategy can provide fast and effective maximum power point tracking and achieve unity power factor connection for three-phase grid-connected photovoltaic systems, and the total harmonic distortion (THD) rate is less than 5%.%研究滑模变结构控制在三相单级光伏并网系统中的应用,设计了一种基于电压定向的滑模变结构控制器,将并网电流分解为有功和无功分量,控制有功分量为MPPT算法给定的参考值,实现最大功率跟踪,控制无功分量为零,实现单位功率因数并网.该方法将矢量控制理论与滑膜控制技术结合,增强了并网系统的鲁棒性,有效提高了系统的响应速度和并网电能质量.组建样机,进行了稳态和动态实验,示波器测试实验波形表明该方法能实现单位功率因子并网,快速跟踪光伏阵列的最大功率,且电流总谐波畸变率(THD)小于5%.

  8. Pilot Preferences on Displayed Aircraft Control Variables

    Science.gov (United States)

    Trujillo, Anna C.; Gregory, Irene M.

    2013-01-01

    The experiments described here explored how pilots want available maneuver authority information transmitted and how this information affects pilots before and after an aircraft failure. The aircraft dynamic variables relative to flight performance were narrowed to energy management variables. A survey was conducted to determine what these variables should be. Survey results indicated that bank angle, vertical velocity, and airspeed were the preferred variables. Based on this, two displays were designed to inform the pilot of available maneuver envelope expressed as bank angle, vertical velocity, and airspeed. These displays were used in an experiment involving control surface failures. Results indicate the displayed limitations in bank angle, vertical velocity, and airspeed were helpful to the pilots during aircraft surface failures. However, the additional information did lead to a slight increase in workload, a small decrease in perceived aircraft flying qualities, and no effect on aircraft situation awareness.

  9. Variable-order fuzzy fractional PID controller.

    Science.gov (United States)

    Liu, Lu; Pan, Feng; Xue, Dingyu

    2015-03-01

    In this paper, a new tuning method of variable-order fractional fuzzy PID controller (VOFFLC) is proposed for a class of fractional-order and integer-order control plants. Fuzzy logic control (FLC) could easily deal with parameter variations of control system, but the fractional-order parameters are unable to change through this way and it has confined the effectiveness of FLC. Therefore, an attempt is made in this paper to allow all the five parameters of fractional-order PID controller vary along with the transformation of system structure as the outputs of FLC, and the influence of fractional orders λ and μ on control systems has been investigated to make the fuzzy rules for VOFFLC. Four simulation results of different plants are shown to verify the availability of the proposed control strategy.

  10. Power inverter implementing phase skipping control

    Science.gov (United States)

    Somani, Utsav; Amirahmadi, Ahmadreza; Jourdan, Charles; Batarseh, Issa

    2016-10-18

    A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control inputs of the first, second and third phase circuitry, where the drivers are configured for receiving phase skipping control signals from the controller and outputting mode selection signals configured to dynamically select an operating mode for the DC/AC inverter from a Normal Control operation and a Phase Skipping Control operation which have different power injection patterns through the first, second and third phase circuitry depending upon the power level.

  11. Variable temperature seat climate control system

    Science.gov (United States)

    Karunasiri, Tissa R.; Gallup, David F.; Noles, David R.; Gregory, Christian T.

    1997-05-06

    A temperature climate control system comprises a variable temperature seat, at least one heat pump, at least one heat pump temperature sensor, and a controller. Each heat pump comprises a number of Peltier thermoelectric modules for temperature conditioning the air in a main heat exchanger and a main exchanger fan for passing the conditioned air from the main exchanger to the variable temperature seat. The Peltier modules and each main fan may be manually adjusted via a control switch or a control signal. Additionally, the temperature climate control system may comprise a number of additional temperature sensors to monitor the temperature of the ambient air surrounding the occupant as well as the temperature of the conditioned air directed to the occupant. The controller is configured to automatically regulate the operation of the Peltier modules and/or each main fan according to a temperature climate control logic designed both to maximize occupant comfort during normal operation, and minimize possible equipment damage, occupant discomfort, or occupant injury in the event of a heat pump malfunction.

  12. Vector Control of Three-Phase Induction Motor with Two Stator Phases Open-Circuit

    Directory of Open Access Journals (Sweden)

    Seyed Hesam Asgari

    2015-06-01

    Full Text Available Variable frequency drives are used to provide reliable dynamic systems and significant reduction in usage of energy and costs of the induction motors. Modeling and control of faulty or an unbalanced three-phase induction motor is obviously different from healthy three-phase induction motor. Using conventional vector control techniques such as Field-Oriented Control (FOC for faulty three-phase induction motor, results in a significant torque and speed oscillation. This research presented a novel method for vector control of three-phase induction motor under fault condition (two-phase open circuit fault. The proposed method for vector control of faulty machine is based on rotor FOC method. A comparison between conventional and modified controller shows that the modified controller has been significantly reduced the torque and speed oscillations.

  13. UPS Delivers Optimal Phase Diagram in High Dimensional Variable Selection

    CERN Document Server

    Ji, Pengsheng

    2010-01-01

    Consider linear regression in the so-called regime of p much larger than n. We propose the UPS as a new variable selection method. This is a Screen and Clean procedure [Wasserman and Roeder (2009)], in which we screen with the Univariate thresholding, and clean with the Penalized MLE. In many situations, the UPS possesses two important properties: Sure Screening and Separable After Screening (SAS). These properties enable us to reduce the original regression problem to many small-size regression problems that can be fitted separately. We measure the performance of variable selection procedure by the Hamming distance. In many situations, we find that the UPS achieves the optimal rate of convergence, and also yields an optimal partition of the so-called phase diagram. In the two-dimensional phase space calibrated by the signal sparsity and signal strength, there is a three-phase diagram shared by many choices of design matrices. In the first phase, it is possible to recover all signals. In the second phase, exa...

  14. Gait variability and motor control in people with knee osteoarthritis.

    Science.gov (United States)

    Alkjaer, Tine; Raffalt, Peter C; Dalsgaard, Helle; Simonsen, Erik B; Petersen, Nicolas C; Bliddal, Henning; Henriksen, Marius

    2015-10-01

    Knee osteoarthritis (OA) is a common disease that impairs walking ability and function. We compared the temporal gait variability and motor control in people with knee OA with healthy controls. The purpose was to test the hypothesis that the temporal gait variability would reflect a more stereotypic pattern in people with knee OA compared with healthy age-matched subjects. To assess the gait variability the temporal structure of the ankle and knee joint kinematics was quantified by the largest Lyapunov exponent and the stride time fluctuations were quantified by sample entropy and detrended fluctuation analysis. The motor control was assessed by the soleus (SO) Hoffmann (H)-reflex modulation and muscle co-activation during walking. The results showed no statistically significant mean group differences in any of the gait variability measures or muscle co-activation levels. The SO H-reflex amplitude was significantly higher in the knee OA group around heel strike when compared with the controls. The mean group difference in the H-reflex in the initial part of the stance phase (control-knee OA) was -6.6% Mmax (95% CI: -10.4 to -2.7, p=0.041). The present OA group reported relatively small impact of their disease. These results suggest that the OA group in general sustained a normal gait pattern with natural variability but with suggestions of facilitated SO H-reflex in the swing to stance phase transition. We speculate that the difference in SO H-reflex modulation reflects that the OA group increased the excitability of the soleus stretch reflex as a preparatory mechanism to avoid sudden collapse of the knee joint which is not uncommon in knee OA.

  15. Using Variable Speed Control on Pump Application

    Directory of Open Access Journals (Sweden)

    Dr.Sc. Aida Spahiu

    2012-06-01

    Full Text Available Pumps are one of the most common variable speed drive (VSD system applications and special interest has focused on improving their energy efficiency by using variable speed control instead of throttling or other less efficient flow control methods. Pumps are the single largest user of electricity in industry in the European Union, consuming 160 TWh per annum of electricity and accounting for 79 million tonnes of carbon dioxide (CO2 emissions [1]. Centrifugal pumps are the most likely pump style to provide a favorable return based on energy savings when applied with a variable speed drive. To help illustrate this, are conducted benchmark testing to document various head and flow scenarios and their corresponding effect on energy savings. Paper shows the relationship of static and friction head in the energy efficiency equation and the effect of motor, pump and VSD efficiencies. The received results are good reference points for engineers and managers of water sector in Albania to select the best prospects for maximizing efficiency and energy savings.

  16. Development of speech motor control: lip movement variability.

    Science.gov (United States)

    Schötz, Susanne; Frid, Johan; Löfqvist, Anders

    2013-06-01

    This study examined variability of lip movements across repetitions of the same utterance as a function of age in Swedish speakers. The specific purpose was to extend earlier findings by examining variability in both phase and amplitude. Subjects were 50 typically developed native Swedish children and adults (28 females, 22 males, aged 5 to 31 yr). Lip movements were recorded during 15 to 20 repetitions of a short Swedish phrase using three-dimensional articulography. After correction for head movements, the kinematic records were expressed in a maxilla-based coordinate system. Movement onset and offset of the utterance were identified using kinematic landmarks. The Euclidean distance between receivers on the upper and lower lips was calculated and subjected to functional data analysis to assess both phase and amplitude variability. Results show a decrease in both indices as a function of age, with a greater reduction of amplitude variability. There was no difference between males and females for either index. The two indices were moderately correlated with each other, suggesting that they capture different aspects of speech production. Utterance duration also decreased with age, but variability was unrelated to duration. The standard deviation of utterance duration also decreased with age. The present results thus suggest that age related changes in speech motor control continue up until 30 years of age.

  17. Miniature, Variable-Speed Control Moment Gyroscope

    Science.gov (United States)

    Bilski, Steve; Kline-Schoder, Robert; Sorensen, Paul

    2011-01-01

    The Miniature Variable-Speed Control Moment Gyroscope (MVS-CMG) was designed for small satellites (mass from less than 1 kg up to 500 kg). Currently available CMGs are too large and heavy, and available miniature CMGs do not provide sufficient control authority for use on practical satellites. This primarily results from the need to greatly increase the speed of rotation of the flywheel in order to reduce the flywheel size and mass. This goal was achieved by making use of a proprietary, space-qualified, high-speed (100,000 rpm) motor technology to spin the flywheel at a speed ten times faster than other known miniature CMGs under development. NASA is supporting innovations in propulsion, power, and guidance and navigation systems for low-cost small spacecraft. One of the key enabling technologies is attitude control mechanisms. CMGs are particularly attractive for spacecraft attitude control since they can achieve higher torques with lower mass and power than reaction wheels, and they provide continuous torque capability that enables precision pointing (in contrast to on-off thruster control). The aim of this work was to develop a miniature, variable-speed CMG that is sized for use on small satellites. To achieve improved agility, these spacecraft must be able to slew at high rate, which requires attitude control actuators that can apply torques on the order of 5 N-m. The MVS-CMG is specifically designed to achieve a high-torque output with a minimum flywheel and system mass. The flywheel can be run over a wide range of speeds, which is important to help reduce/eliminate potential gimbal lock, and can be used to optimize the operational envelope of the CMG.

  18. Part 3: Pharmacogenetic Variability in Phase II Anticancer Drug Metabolism

    Science.gov (United States)

    Deenen, Maarten J.; Cats, Annemieke; Beijnen, Jos H.

    2011-01-01

    Equivalent drug doses may lead to wide interpatient variability in drug response to anticancer therapy. Known determinants that may affect the pharmacological response to a drug are, among others, nongenetic factors, including age, gender, use of comedication, and liver and renal function. Nonetheless, these covariates do not explain all the observed interpatient variability. Differences in genetic constitution among patients have been identified to be important factors that contribute to differences in drug response. Because genetic polymorphism may affect the expression and activity of proteins encoded, it is a key covariate that is responsible for variability in drug metabolism, drug transport, and pharmacodynamic drug effects. We present a series of four reviews about pharmacogenetic variability. This third part in the series of reviews is focused on genetic variability in phase II drug-metabolizing enzymes (glutathione S-transferases, uridine diphosphoglucuronosyl transferases, methyltransferases, sulfotransferases, and N-acetyltransferases) and discusses the effects of genetic polymorphism within the genes encoding these enzymes on anticancer drug therapy outcome. Based on the literature reviewed, opportunities for patient-tailored anticancer therapy are proposed. PMID:21659608

  19. Insights into gait disorders: walking variability using phase plot analysis, Huntington's disease.

    Science.gov (United States)

    Collett, Johnny; Esser, Patrick; Khalil, Hanan; Busse, Monica; Quinn, Lori; DeBono, Katy; Rosser, Anne; Nemeth, Andrea H; Dawes, Helen

    2014-09-01

    Huntington's disease (HD) is a progressive inherited neurodegenerative disorder. Identifying sensitive methodologies to quantitatively measure early motor changes have been difficult to develop. This exploratory observational study investigated gait variability and symmetry in HD using phase plot analysis. We measured the walking of 22 controls and 35 HD gene carriers (7 premanifest (PreHD)), 16 early/mid (HD1) and 12 late stage (HD2) in Oxford and Cardiff, UK. The unified Huntington's disease rating scale-total motor scores (UHDRS-TMS) and disease burden scores (DBS) were used to quantify disease severity. Data was collected during a clinical walk test (8.8 or 10 m) using an inertial measurement unit attached to the trunk. The 6 middle strides were used to calculate gait variability determined by spatiotemporal parameters (co-efficient of variation (CoV)) and phase plot analysis. Phase plots considered the variability in consecutive wave forms from vertical movement and were quantified by SDA (spatiotemporal variability), SDB (temporal variability), ratio ∀ (ratio SDA:SDB) and Δangleβ (symmetry). Step time CoV was greater in manifest HD (p0.05). Phase plot analysis identified differences between manifest HD and controls for SDB, Ratio ∀ and Δangle (all pplot analysis may be a sensitive method of detecting gait changes in HD and can be performed quickly during clinical walking tests.

  20. Nonlinear Phase Control and Anomalous Phase Matching in Plasmonic Metasurfaces

    CERN Document Server

    Almeida, Euclides; Prior, Yehiam

    2015-01-01

    Metasurfaces, and in particular those containing plasmonic-based metallic elements, constitute a particularly attractive set of materials. By means of modern nanolithographic fabrication techniques, flat, ultrathin optical elements may be constructed. However, in spite of their strong optical nonlinearities, plasmonic metasurfaces have so far been investigated mostly in the linear regime. Here we introduce full nonlinear phase control over plasmonic elements in metasurfaces. We show that for nonlinear interactions in a phase-gradient nonlinear metasurface a new anomalous nonlinear phase matching condition prevails, which is the nonlinear analog of the generalized Snell law demonstrated for linear metasurfaces. This phase matching condition is very different from the other known phase matching schemes. The subwavelength phase control of optical nonlinearities provides a foundation for the design of flat nonlinear optical elements based on metasurfaces. Our demonstrated flat nonlinear elements (i.e. lenses) act...

  1. Quantum information processing in phase space: A modular variables approach

    Science.gov (United States)

    Ketterer, A.; Keller, A.; Walborn, S. P.; Coudreau, T.; Milman, P.

    2016-08-01

    Binary quantum information can be fault-tolerantly encoded in states defined in infinite-dimensional Hilbert spaces. Such states define a computational basis, and permit a perfect equivalence between continuous and discrete universal operations. The drawback of this encoding is that the corresponding logical states are unphysical, meaning infinitely localized in phase space. We use the modular variables formalism to show that, in a number of protocols relevant for quantum information and for the realization of fundamental tests of quantum mechanics, it is possible to loosen the requirements on the logical subspace without jeopardizing their usefulness or their successful implementation. Such protocols involve measurements of appropriately chosen modular variables that permit the readout of the encoded discrete quantum information from the corresponding logical states. Finally, we demonstrate the experimental feasibility of our approach by applying it to the transverse degrees of freedom of single photons.

  2. Intra-task variability of trunk coordination during a rate-controlled bipedal dance jump.

    Science.gov (United States)

    Smith, Jo Armour; Siemienski, Adam; Popovich, John M; Kulig, Kornelia

    2012-01-01

    In this study, we investigated trunk coordination during rate-controlled bipedal vertical dance jumps. The aims of the study were to investigate the pattern of coordination and the magnitude of coordination variability within jump phases and relative to phase-defining events during the jump. Lumbar and thoracic kinematics were collected from seven dancers during a series of jumps at 95 beats per minute. The vector coding technique was used to quantify the pattern and variability of trunk coordination. Coordination was predominantly anti-phase during propulsion and landing. Mean coordination variability peaked just before the landing phase and at the transition from landing to propulsion phases, and was lowest during the propulsion phase just before toe-off. The results indicate that peaks in variability could be explained by task and phase-specific biomechanical demands.

  3. Variability control: key to regulatory compliance and sustainability goals.

    Science.gov (United States)

    Englande, A J; Eckenfelder, W W; Jin, G

    2006-01-01

    The focus of this paper is on variability concerns in wastewater treatment and approaches to control unacceptable fluctuations in effluent quality. Areas considered include: factors contributing to variability in both waste loads and process technology performance; variability assessment; control of variability employing the process best management practice (BMP); design/operation of biological waste treatment technologies for variability reduction; and modelling to enhance process control.

  4. Phase Change Fabrics Control Temperature

    Science.gov (United States)

    2009-01-01

    Originally featured in Spinoff in 1997, Outlast Technologies Inc. (formerly Gateway Technologies Inc.) has built its entire product line on microencapsulated phase change materials, developed in Small Business Innovation Research (SBIR) contracts with Johnson Space Center after initial development for the U.S. Air Force. The Boulder, Colorado-based company acquired the exclusive patent rights and now integrates these materials into textiles or onto finished apparel, providing temperature regulation in bedding materials and a full line of apparel for both ordinary and extreme conditions.

  5. Fuzzy Variable Structure Control of Photovoltaic MPPT System

    Institute of Scientific and Technical Information of China (English)

    LI Wei; ZHU Xin-jian; CAO Guang-yi

    2006-01-01

    In order to reduce chattering phenomenon of variable structure control, a fuzzy variable structure control method is adopted and applied in the photovoitaic maximum power point tracking (MPPT) control system. Firstly, the electric features of PV cells and a dynamic model of photovoltaic system with a DC-DC buck converter are analysed. Then a hybrid fuzzy variable structure controller is designed. The controller is composed of a fuzzy variable structure control term and a supervisory control term. The former is the main part of the controller and the latter is used to ensure the stability of the system. Finally, the conventional variable structure control method and the fuzzy variable structure control method are applied respectively. The comparing of simulation results shows the superiority of the latter.

  6. Nonlinear and Variable Structure Excitation Controller for Power System Stability

    Institute of Scientific and Technical Information of China (English)

    Wang Ben; Ronnie Belmans

    2006-01-01

    A new nonlinear variable structure excitation controller is proposed. Its design combines the differential geometry theory and the variable structure controlling theory. The mathematical model in the form of "an affine nonlinear system" is set up for the control of a large-scale power system. The static and dynamic performances of the nonlinear variable structure controller are simulated. The response of system with the controller proposed is compared to that of the nonlinear optimal controller when the system is subjected to a variety of disturbances. Simulation results show that the nonlinear variable structure excitation controller gives more satisfactorily static and dynamic performance and better robustness.

  7. An improved Lobatto discrete variable representation by a phase optimisation and variable mapping method

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dequan [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023 (China); Cong, Shu-Lin, E-mail: shlcong@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Sun, Zhigang, E-mail: zsun@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical and Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023 (China); Center for Advanced Chemical Physics and 2011 Frontier Center for Quantum Science and Technology, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026 (China)

    2015-09-08

    Highlights: • An optimised finite element discrete variable representation method is proposed. • The method is tested by solving one and two dimensional Schrödinger equations. • The method is quite efficient in solving the molecular Schrödinger equation. • It is very easy to generalise the method to multidimensional problems. - Abstract: The Lobatto discrete variable representation (LDVR) proposed by Manoloupolos and Wyatt (1988) has unique features but has not been generally applied in the field of chemical dynamics. Instead, it has popular application in solving atomic physics problems, in combining with the finite element method (FE-DVR), due to its inherent abilities for treating the Coulomb singularity in spherical coordinates. In this work, an efficient phase optimisation and variable mapping procedure is proposed to improve the grid efficiency of the LDVR/FE-DVR method, which makes it not only be competing with the popular DVR methods, such as the Sinc-DVR, but also keep its advantages for treating with the Coulomb singularity. The method is illustrated by calculations for one-dimensional Coulomb potential, and the vibrational states of one-dimensional Morse potential, two-dimensional Morse potential and two-dimensional Henon–Heiles potential, which prove the efficiency of the proposed scheme and promise more general applications of the LDVR/FE-DVR method.

  8. Optimizing discrete control systems with phase limitations

    Energy Technology Data Exchange (ETDEWEB)

    Shakhverdian, S.B.; Abramian, A.K.

    1981-01-01

    A new method is proposed for solving discrete problems of optimizing control systems with limitations on the phase coordinates. Results are given from experimental research which demonstrate the need to introduce tangential limitations independent of the method of accounting for the phase limitations.

  9. Robust Fuzzy Control for Doubly Fed Wind Power Systems with Variable Speed Based on Variable Structure Control Technique

    Directory of Open Access Journals (Sweden)

    Xizheng Zhang

    2014-01-01

    Full Text Available The design of a variable structure sliding-mode controller (SMC for a variable speed wind turbine with double-fed induction-generator, based on the fuzzy logic, is described in this paper. The purpose of this controller is to maximize the energy capture by operating the turbine at the optimal rotational speed as well as fast and stable generator response. The dynamics of both the turbine and the generator are modeled to exhibit their mechanical/electrical characteristics. Two global sliding-mode controllers, which eliminate the reaching phase of SMC and the sliding-mode motion starts from the beginning, are designed to guarantee the robust tracking of both the optimal blade-rotor speed and the reference generator torque/flux in the whole process, despite the parametric uncertainty and external disturbance. To reduce the adverse chattering effect of the conventional SMC, the adaptive fuzzy inference strategy is adopted to deduce the adjustable switch gain, instead of the fixed gains. Simulation results show that the proposed controller achieves global asymptotic tracking, satisfied torque/flux responses, and has better performance and higher utilization ratio of wind energy than the conventional feedback-linearization method.

  10. APPROXIMATION LAWS OF DISCRETE-TIME VARIABLE STRUCTURE CONTROL SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Two new approximation laws of sliding mode for discrete-time variable structure control systems are proposed in this paper. By applying the proposed approximation laws of sliding mode to discrete-time variable structure control systems,the stability of origin can be guaranteed,and the chattering along the switching surface caused by discrete-time variable structure control can be restrained effectively. In designing of these approximation laws,the problem that the system control input is restricted is also ...

  11. Double acting stirling engine phase control

    Science.gov (United States)

    Berchowitz, David M.

    1983-01-01

    A mechanical device for effecting a phase change between the expansion and compression volumes of a double-acting Stirling engine uses helical elements which produce opposite rotation of a pair of crankpins when a control rod is moved, so the phase between two pairs of pistons is changed by +.psi. and the phase between the other two pairs of pistons is changed by -.psi.. The phase can change beyond .psi.=90.degree. at which regenerative braking and then reversal of engine rotation occurs.

  12. Variable Rail Voltage Control of a Brushless DC (BLDC) Motor

    Science.gov (United States)

    2013-01-01

    Variable Rail Voltage Control of a Brushless DC (BLDC) Motor by Yuan Chen, Joseph Conroy, and William Nothwang ARL-TR-6308 January 2013...TR-6308 January 2013 Variable Rail Voltage Control of a Brushless DC (BLDC) Motor Yuan Chen, Joseph Conroy, and William Nothwang Sensors...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Variable Rail Voltage Control of a Brushless DC (BLDC) Motor 5a. CONTRACT NUMBER 5b. GRANT

  13. Approximation law for discrete-time variable structure control systems

    Institute of Scientific and Technical Information of China (English)

    Yan ZHENG; Yuanwei JING

    2006-01-01

    Two approximation laws of sliding mode for discrete-time variable structure control systems are proposed to overcome the limitations of the exponential approximation law and the variable rate approximation law. By applying the proposed approximation laws of sliding mode to discrete-time variable structure control systems, the stability of origin can be guaranteed, and the chattering along the switching surface caused by discrete-time variable structure control can be restrained effectively. In designing of approximation laws, the problem that the system control input is restricted is also considered, which is very important in practical systems. Finally a simulation example shows the effectiveness of the two approximation laws proposed.

  14. The Development of New Measures of Cognitive Variables in Elementary School Children (Phase II). Final Report.

    Science.gov (United States)

    Asher, J. William; And Others

    This report covers Phase II of a two-phase project concerned with the development of new measures of cognitive variables in elementary school children. The four tasks undertaken in Phase II were: (1) prepare, revise and describe instruments designed to measure the cognitive variables categorized as concept formation, language development, logical…

  15. Vibration control using a variable coil-based friction damper

    Science.gov (United States)

    Amjadian, Mohsen; Agrawal, Anil K.

    2017-04-01

    This paper is focused on the analytical model, design, and simulation of a variable coil-based friction damper (VCBFD) for vibration control of structures. The proposed VCBFD is composed of a soft ferromagnetic plate, made of a linear magnetic material, and two identical thick rectangular air-core coils connected in parallel, each one attached to the plate through a friction pad. The friction force is provided by a normal force produced through an attractive electromagnetic interaction between the air-core coils (ACs) and the soft ferromagnetic plate when sliding relative to each other. The magnitude of the normal force in the damper is varied by a semi-active controller that controls the command current passing through the ACs. To demonstrate the efficiency of the proposed VCBFD and its semi-active controller, it has been implemented on a two-degree-of-freedom (2DOF) base-isolated model subjected to the acceleration components of three records of strong earthquakes. The results show that the performance of the proposed VCBFD in its passive-on mode is overshadowed by the undesirable effects of stick-slip motion. However, the damper in its semi-active mode is more successful in not only reducing the displacement of the base-floor but also avoiding stick-slip motion, due to acting completely in its sliding phase.

  16. Vector Control Algorithm for Electric Vehicle AC Induction Motor Based on Improved Variable Gain PID Controller

    Directory of Open Access Journals (Sweden)

    Gang Qin

    2015-01-01

    Full Text Available The acceleration performance of EV, which affects a lot of performances of EV such as start-up, overtaking, driving safety, and ride comfort, has become increasingly popular in recent researches. An improved variable gain PID control algorithm to improve the acceleration performance is proposed in this paper. The results of simulation with Matlab/Simulink demonstrate the effectiveness of the proposed algorithm through the control performance of motor velocity, motor torque, and three-phase current of motor. Moreover, it is investigated that the proposed controller is valid by comparison with the other PID controllers. Furthermore, the AC induction motor experiment set is constructed to verify the effect of proposed controller.

  17. Variable pattern contamination control under positive pressure

    Energy Technology Data Exchange (ETDEWEB)

    Philippi, H.M. [Chalk River Labs., Ontario (Canada)

    1997-08-01

    Airborne contamination control in nuclear and biological laboratories is traditionally achieved by directing the space ventilation air at subatmospheric pressures in one fixed flow pattern. However, biological and nuclear contamination flow control in the new Biological Research Facility, to be commissioned at the Chalk River Laboratories in 1996, will have the flexibility to institute a number of contamination control patterns, all achieved at positive (above atmospheric) pressures. This flexibility feature, made possible by means of a digitally controlled ventilation system, changes the facility ventilation system from being a relatively rigid building service operated by plant personnel into a flexible building service which can be operated by the facility research personnel. This paper focuses on and describes the application of these unique contamination control features in the design of the new Biological Research Facility. 3 refs., 7 figs.

  18. Variable emissivity laser thermal control system

    Science.gov (United States)

    Milner, Joseph R.

    1994-01-01

    A laser thermal control system for a metal vapor laser maintains the wall mperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser.

  19. Advanced Emissions Control Development Program: Phase III

    Energy Technology Data Exchange (ETDEWEB)

    G.T. Amrhein; R.T. Bailey; W. Downs; M.J. Holmes; G.A. Kudlac; D.A. Madden

    1999-07-01

    The primary objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. The project goal is to effectively control air toxic emissions through the use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESPs), fabric filters (baghouses - BH), and wet flue gas desulfurization systems (WFGD). Development work concentrated on the capture of trace metals, fine particulate, hydrogen chloride and hydrogen fluoride, with an emphasis on the control of mercury. The AECDP project is jointly funded by the US Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (OCDO), and Babcock and Wilcox, a McDermott company (B and W). This report discusses results of all three phases of the AECDP project with an emphasis on Phase III activities. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on characterization of the emissions of mercury and other air toxics and the control of these emissions for typical operating conditions of conventional flue gas clean-up equipment. Some general comments that can be made about the control of air toxics while burning a high-sulfur bituminous coal are as follows: (1) particulate control devices such as ESP's and baghouses do a good job of removing non-volatile trace metals, (2) particulate control devices (ESPs and baghouses) effectively remove the particulate-phase mercury, but the particulate-phase mercury was only a small fraction of the total for the coals tested, (3) wet scrubbing can effectively remove hydrogen chloride and hydrogen fluoride, and (4) wet scrubbers show good potential for the removal of mercury when operated under certain conditions, however, for certain applications, system enhancements can be required to achieve

  20. Servo Controlled Variable Pressure Modification to Space Shuttle Hydraulic Pump

    Science.gov (United States)

    Kouns, H. H.

    1983-01-01

    Engineering drawings show modifications made to the constant pressure control of the model AP27V-7 hydraulic pump to an electrically controlled variable pressure setting compensator. A hanger position indicator was included for continuously monitoring hanger angle. A simplex servo driver was furnished for controlling the pressure setting servovalve. Calibration of the rotary variable displacement transducer is described as well as pump performance and response characteristics.

  1. Explaining finite state machine characteristics using variable structure control

    Energy Technology Data Exchange (ETDEWEB)

    Feddema, J.T.; Robinett, R.D.; Driessen, B.J.

    1997-10-01

    This paper describes how variable structure control can be used to describe the overall behavior of multiple autonomous robotic vehicles with simple finite state machine rules. The importance of this result is that it allows for the design of provably asymptotically stable group behaviors from a set of simple control laws and appropriate switching points with variable structure control. The ability to prove convergence to a goal is especially important for applications such as locating military targets or land mines.

  2. Sliding Mode Control of Induction Motor Phase Currents

    DEFF Research Database (Denmark)

    Hansen, R.B.; Hattel, T.; Bork, J

    1995-01-01

    Sliding mode control of induction motor phase currents are investigated through development of two control concepts.......Sliding mode control of induction motor phase currents are investigated through development of two control concepts....

  3. Sliding Mode Control of Induction Motor Phase Currents

    DEFF Research Database (Denmark)

    Hansen, R.B.; Hattel, T.; Bork, J

    1995-01-01

    Sliding mode control of induction motor phase currents are investigated through development of two control concepts.......Sliding mode control of induction motor phase currents are investigated through development of two control concepts....

  4. Voltage-controlled narrowband and wide, variable-range four-segment quartz crystal oscillator.

    Science.gov (United States)

    Ruslan, Ruzaini; Satoh, Tomio; Akitsu, Tetsuya

    2012-03-01

    In this work, our goal is to develop a voltage-controlled variable-frequency quartz crystal oscillator with narrowband response, wide, variable frequency range and the capacity to oscillate across the series resonance frequency using a four-segment configuration of a quartz crystal oscillator. In conventional quartz oscillators, the quartz resonator is inserted in the feedback loop between the input and the output of the active circuit, providing sufficient gain and the phase relation. In the oscillator developed here, the quartz crystal resonator is inserted between the loop circuit and the ground potential. The performance of the voltage-controlled variable-frequency oscillator is demonstrated across the series resonance frequency.

  5. VARIABLE STRUCTURE CONTROL APPLIED IN ELECTRO-HYDRAULIC SERVO SYSTEM WITH ANN

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The variable structure control (VSC) theory is applied to the electro-hydraulic servo system here. The VSC control law is achieved using Lyapunov method and pole placement. To eliminate the chattering phenomena, a saturation function is adopted. The proposed VSC approach is fairly robust to load disturbance and system parameter variation. Since the distortion including phase lag and amplitude attenuation occurs in the system sinusoid response, the amplitude and phase control (APC)algorithm, based on Adaline neural network and using LMS algorithm, is developed for distortion cancellation. The APC controller is simple and can on-line adjust, thus it gives accurate tracking.

  6. Sample-Clock Phase-Control Feedback

    Science.gov (United States)

    Quirk, Kevin J.; Gin, Jonathan W.; Nguyen, Danh H.; Nguyen, Huy

    2012-01-01

    To demodulate a communication signal, a receiver must recover and synchronize to the symbol timing of a received waveform. In a system that utilizes digital sampling, the fidelity of synchronization is limited by the time between the symbol boundary and closest sample time location. To reduce this error, one typically uses a sample clock in excess of the symbol rate in order to provide multiple samples per symbol, thereby lowering the error limit to a fraction of a symbol time. For systems with a large modulation bandwidth, the required sample clock rate is prohibitive due to current technological barriers and processing complexity. With precise control of the phase of the sample clock, one can sample the received signal at times arbitrarily close to the symbol boundary, thus obviating the need, from a synchronization perspective, for multiple samples per symbol. Sample-clock phase-control feedback was developed for use in the demodulation of an optical communication signal, where multi-GHz modulation bandwidths would require prohibitively large sample clock frequencies for rates in excess of the symbol rate. A custom mixedsignal (RF/digital) offset phase-locked loop circuit was developed to control the phase of the 6.4-GHz clock that samples the photon-counting detector output. The offset phase-locked loop is driven by a feedback mechanism that continuously corrects for variation in the symbol time due to motion between the transmitter and receiver as well as oscillator instability. This innovation will allow significant improvements in receiver throughput; for example, the throughput of a pulse-position modulation (PPM) with 16 slots can increase from 188 Mb/s to 1.5 Gb/s.

  7. Variable universe adaptive fuzzy control on the quadruple inverted pendulum

    Institute of Scientific and Technical Information of China (English)

    李洪兴; 苗志宏; 王家银

    2002-01-01

    This paper focuses on the control problem of the quadruple inverted pendulum by variable universe adaptive fuzzy control.First,the mathematical model on the quadruple inverted pendulum is described and its controllability is versified.Then,an efficient controller on the quadruple inverted pendulum is designed by using variable universe adaptive fuzzy control theory.Finally the simulation of the quadruple inverted pendulum is shown in detail.Besides,the experimental results on the hardware systems,i.e.real object systems,on a single inverted pendulum,a double inverted pendulum and a triple inverted pendulum are briefly introduced.``

  8. Variability in GRMHD simulations of Sgr A$^*$: Implications for EHT closure phase observations

    CERN Document Server

    Medeiros, Lia; Özel, Feryal; Psaltis, Dimitrios; Kim, Junhan; Marrone, Daniel; Sądowski, Aleksander

    2016-01-01

    The observable quantities that carry the most information regarding the structures of the images of black holes in the interferometric observations with the Event Horizon Telescope are the closure phases along different baseline triangles. We use long time span, high cadence, GRMHD+radiative transfer models of Sgr A$^*$ to investigate the expected variability of closure phases in such observations. We find that, in general, closure phases along small baseline triangles show little variability, except in the cases when one of the triangle vertices crosses one of a small regions of low visibility amplitude. The closure phase variability increases with the size of the baseline triangle, as larger baselines probe the small-scale structures of the images, which are highly variable. On average, the jet-dominated MAD models show less closure phase variability than the disk-dominated SANE models, even in the large baseline triangles, because the images from the latter are more sensitive to the turbulence in the accre...

  9. Accurate Control of Josephson Phase Qubits

    Science.gov (United States)

    2016-04-14

    61 ~1986!. 23 K. Kraus, States, Effects, and Operations: Fundamental Notions of Quantum Theory, Lecture Notes in Physics , Vol. 190 ~Springer-Verlag... PHYSICAL REVIEW B 68, 224518 ~2003!Accurate control of Josephson phase qubits Matthias Steffen,1,2,* John M. Martinis,3 and Isaac L. Chuang1 1Center...for Bits and Atoms and Department of Physics , MIT, Cambridge, Massachusetts 02139, USA 2Solid State and Photonics Laboratory, Stanford University

  10. The Education of Attention as Explanation of Variability of Practice Effects : Learning the Final Approach Phase in a Flight Simulator

    Science.gov (United States)

    Huet, Michael; Jacobs, David M.; Camachon, Cyril; Missenard, Olivier; Gray, Rob; Montagne, Gilles

    2011-01-01

    The present study reports two experiments in which a total of 20 participants without prior flight experience practiced the final approach phase in a fixed-base simulator. All participants received self-controlled concurrent feedback during 180 practice trials. Experiment 1 shows that participants learn more quickly under variable practice…

  11. The Education of Attention as Explanation of Variability of Practice Effects : Learning the Final Approach Phase in a Flight Simulator

    Science.gov (United States)

    Huet, Michael; Jacobs, David M.; Camachon, Cyril; Missenard, Olivier; Gray, Rob; Montagne, Gilles

    2011-01-01

    The present study reports two experiments in which a total of 20 participants without prior flight experience practiced the final approach phase in a fixed-base simulator. All participants received self-controlled concurrent feedback during 180 practice trials. Experiment 1 shows that participants learn more quickly under variable practice…

  12. Control of a Unified Chaotic System via Single Variable Feedback

    Science.gov (United States)

    Guo, Rong-Wei; Vincent E., U.

    2009-09-01

    Based on the LaSalle invariance principle, we propose a simple adaptive-feedback for controlling the unified chaotic system. We show explicitly with numerical proofs that our method can easily achieve the control of chaos in the unified chaotic system using only a single variable feedback. The present controller, to our knowledge, is the simplest control scheme for controlling a unified chaotic system.

  13. DYNAMICAL VARIABLE STRUCTURE CONTROL OF A HELICOPTER IN VERTICAL FLIGHT

    OpenAIRE

    Sira-Ramirez, Hebertt; Zribi, Mohamed; Ahmad, Shaheen

    1991-01-01

    In this article, a dynamical multivariable discontinuous feedback control strategy of the sliding nlode type is proposed for the altitude stabilization of a nonlinear helicopter model in vertical flight. Vlrhile retaining the basic robustness features associated to sliding mode control policies, the proposed approach also results in smoothed out (i.e., non-chattering) input trajectories and controlled state variable responses.

  14. Combined variable speed/variable pitch controlled 3-bladed wind turbine: Control strategies; Dobbelt styrbar 3-bladet vindmoelle: Reguleringsstrategier

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.; Bindner, H.

    1998-12-01

    This report is a part of the project `Combined variable speed/variable pitch controlled 3-bladed wind turbine`. The purpose of the project is to investigate a variable speed/variable pitch controlled wind turbine. The total reporting work of the projects is divided in 2 reports: Control Strategies (R-1071) (the current report); Comparison between pitch controlled wind turbine and pitch controlled wind turbine with variable speed (R-1072). The current report presents two control strategies, which can be used in a variable speed/variable pitch wind turbine. These control strategies are investigated regarding power production, structural loads and power quality. A static model is developed in order to establish the control strategy and a dynamic model is used to analyse the loads and the performance of the control. First the reports presents the background/motivation for combining variable speed with variable pitch wind turbine, after which an investigation of the power production for different control strategies it presented. The report further contains a nonlinear simulation model for a wind turbine, including control systems and frequency converter. The model, developed for control purposes, includes a model for tower and flapwise blade bending, a model for the pitch system, nonlinear aerodynamic, frequency converter, turbulens and drive train. The model is validated through comparisons with measurements performed on a test facility, which consists of a Vestas V27-225 kW wind turbine with a SAMI-STAR 400 kVA frequency converter from ABB. The model is used both to establish the parameters of the controller and afterwards to investigate the performance of a variable speed wind turbine. In report R-1072 a comparison between pitch controlled wind turbine and pitch controlled wind turbine with variable speed is presented based on measurements from the test facility. The project participants were Vestas Wind Systems A/S, ABB Energy and Industry A/S and Risoe National

  15. Liquid crystal multi-mode lenses and axicons based on electronic phase shift control.

    Science.gov (United States)

    Kirby, Andrew K; Hands, Philip J; Love, Gordon D

    2007-10-17

    We report on the principle of operation, construction and testing of a liquid crystal lens which is controlled by distributing voltages across the control electrodes, which are in turn controlled by adjusting the phase of the applied voltages. As well as (positive and negative) defocus, then lenses can be used to control tip/tilt, astigmatism, and to create variable axicons.

  16. Variable universe stable adaptive fuzzy control of nonlinear system

    Institute of Scientific and Technical Information of China (English)

    李洪兴; 苗志宏; 王加银

    2002-01-01

    A kind of stable adaptive fuzzy control of nonlinear system is implemented using variable universe method. First of all, the basic structure of variable universe adaptive fuzzy controllers is briefly introduced. Then the contraction-expansion factor that is a key tool of variable universe method is defined by means of integral regulation idea, and a kind of adaptive fuzzy controllers is designed by using such a contraction-expansion factor. The simulation on first order nonlinear system is done. Secondly, it is proved that the variable universe adaptive fuzzy control is asymptotically stable by use of Lyapunov theory. The simulation on the second order nonlinear system shows that its simulation effect is also quite good. Finally a useful tool, called symbolic factor, is proposed, which may be of universal significance. It can greatly reduce the settling time and enhance the robustness of the system.

  17. Miniature, Variable-Speed Control Moment Gyroscope Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of this project is to design, develop, demonstrate, and deliver a miniature, variable speed control moment gyroscope (MVS CMG) for use on small...

  18. Variable Neural Adaptive Robust Control: A Switched System Approach

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Jianming; Hu, Jianghai; Zak, Stanislaw H.

    2015-05-01

    Variable neural adaptive robust control strategies are proposed for the output tracking control of a class of multi-input multi-output uncertain systems. The controllers incorporate a variable-structure radial basis function (RBF) network as the self-organizing approximator for unknown system dynamics. The variable-structure RBF network solves the problem of structure determination associated with fixed-structure RBF networks. It can determine the network structure on-line dynamically by adding or removing radial basis functions according to the tracking performance. The structure variation is taken into account in the stability analysis of the closed-loop system using a switched system approach with the aid of the piecewise quadratic Lyapunov function. The performance of the proposed variable neural adaptive robust controllers is illustrated with simulations.

  19. Intelligent control for large-scale variable speed variable pitch wind turbines

    Institute of Scientific and Technical Information of China (English)

    Xinfang ZHANG; Daping XU; Yibing LIU

    2004-01-01

    Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances.Automatic control is crucial for the efficiency and reliability of wind turbines.On the basis of simplified and proper model of variable speed variable pitch wind turbines,the effective wind speed is estimated using extended Kalman filter.Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other.At below-rated wind speed,the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture.At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power.The simulation shows the effectiveness of the intelligent control.

  20. A statistical combustion phase control approach of SI engines

    Science.gov (United States)

    Gao, Jinwu; Wu, Yuhu; Shen, Tielong

    2017-02-01

    In order to maximize the performance of internal combustion engine, combustion phase is usually controlled to track its desired reference. However, suffering from the cyclic variability of combustion, it is difficulty but meaningful to control mean of combustion phase and constrain its variance. As a combustion phase indicator, the location of peak pressure (LPP) is utilized for real-time combustion phase control in this research. The purpose of the proposed method is to ensure the mean of LPP statistically tracks its reference and constrains the standard deviation of LPP distribution. To achieve this, LPP is first calculated based on the cylinder pressure sensor, and its characteristics are analyzed at the steady-state operating condition, then the distribution of LPP is examined online using hypothesis test criterion. On the basis of the presented statistical algorithm, current mean of LPP is applied in the feedback channel for designing spark advance adjustment law, and the stability of closed-loop system is theoretically ensured according to a steady statistical model. Finally, the proposed strategy is verified on a spark ignition gasoline engine.

  1. Variability of the pharyngeal phase of swallow in the cat.

    Directory of Open Access Journals (Sweden)

    Daniel G Spearman

    Full Text Available The pharyngeal phase of swallow has been thought to be a stereotypical motor behavior.This is a prospective, preclinical, hypothesis driven, one group by three-task design.We sought to compare the effects of pharyngeal swabbing, water only, and water plus punctate mechanical stimulation on the spatiotemporal features of the pharyngeal phase of swallow in the cat. Swallow was elicited under these three conditions in six anaesthetized cats. Electromyographic activity was recorded from seven muscles used to evaluate swallow: mylohyoid, geniohyoid, thyrohyoid, thyroarytenoid, thyropharyngeus, cricopharyngeus, and parasternal.Pharyngeal swabbing in comparison to the other stimulus conditions, results in decreases in post-swallow cricopharyngeus activity (upper esophageal sphincter; a significant increase in parasternal (schluckatmung; swallow breath activity; and increases in thyrohyoid (laryngeal elevator, thyroarytenoid (laryngeal adductor and parasternal muscles burst duration. Pearson correlations were found of moderate strength between 19% of burst duration comparisons and weak to moderate relationships between 29% of burst amplitude comparisons. However, there were no positive significant relationships between phase durations and electromyogram amplitudes between any of the muscles studied during swallow.The results support the concept that a stereotypical behavior, such as pharyngeal swallowing in animal models, can be modified by sensory feedback from pharyngeal mucosal mechanoreceptors. Furthermore, differences in swallow phase durations and amplitudes provide evidence that separate regulatory mechanisms exist which regulate spatial and temporal aspects of the behavior.

  2. Control of Variable Speed Variable Pitch Wind Turbine at Above and Below Rated Wind Speed

    Directory of Open Access Journals (Sweden)

    Saravanakumar Rajendran

    2014-01-01

    Full Text Available The paper presents a nonlinear approach to wind turbine (WT using two-mass model. The main aim of the controller in the WT is to maximize the energy output at varying wind speed. In this work, a combination of linear and nonlinear controllers is adapted to variable speed variable pitch wind turbines (VSVPWT system. The major operating regions of the WT are below (region 2 and above rated (region 3 wind speed. In these regions, generator torque control (region 2 and pitch control (region 3 are used. The controllers in WT are tested for below and above rated wind speed for step and vertical wind speed profile. The performances of the controllers are analyzed with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence WT dynamic simulation. In this paper, two nonlinear controllers, that is, sliding mode control (SMC and integral sliding mode control (ISMC, have been applied for region 2, whereas for pitch control in region 3 conventional PI control is used. In ISMC, the sliding manifold makes use of an integral action to show effective qualities of control in terms of the control level reduction and sliding mode switching control minimization.

  3. Adaptive Variable Structure Controller Application to Induction Motor Drive

    Directory of Open Access Journals (Sweden)

    Prasad. Ch,

    2014-07-01

    Full Text Available Variable structure control is an adaptive control that gives robust performance of a drive with parameter variation and load torque disturbance. Variable control structure is a robust control scheme based on the concept of changing the structure of the controller in response to the changing state of the system in order to obtain a desired response. The control is nonlinear and can be applied to the linear or nonlinear plant. A high speed switching control action is used to switch between different structures of the controller and the trajectory of the system is forced to move along a chosen switching manifold in the state space. The controller detects the deviation of the actual trajectory from the reference trajectory and corresponding changes the switching strategy to restore the tracking. Prominent characteristics such as invariance, robustness, order reduction, and control chattering are discussed in detail. Methods for coping with chattering are presented. Both linear and nonlinear systems are considered. By using Variable structure controller to control the step change in reference speed and drive system under load torque variations.

  4. FPGA implementation of high-frequency multiple PWM for variable voltage variable frequency controller

    Energy Technology Data Exchange (ETDEWEB)

    Boumaaraf, Abdelâali, E-mail: aboumaaraf@yahoo.fr [Université Abbès Laghrour, Laboratoire des capteurs, Instrumentations et procédés (LCIP), Khenchela (Algeria); University of Farhat Abbas Setif1, Sétif, 19000 (Algeria); Mohamadi, Tayeb [University of Farhat Abbas Setif1, Sétif, 19000 (Algeria); Gourmat, Laïd [Université Abbès Laghrour, Khenchela, 40000 (Algeria)

    2016-07-25

    In this paper, we present the FPGA implementation of the multiple pulse width modulation (MPWM) signal generation with repetition of data segments, applied to the variable frequency variable voltage systems and specially at to the photovoltaic water pumping system, in order to generate a signal command very easily between 10 Hz to 60 Hz with a small frequency and reduce the cost of the control system.

  5. In search of control variables : A systems approach

    NARCIS (Netherlands)

    Dalenoort, GJ

    1997-01-01

    Motor processes cannot be modeled by a single (unified) model. Instead, a number of models at different levels of description are needed. The concepts of control and control variable only make sense at the functional level. A clear distinction must be made between external models and internal models

  6. Modeling, analysis and control of a variable geometry actuator

    NARCIS (Netherlands)

    Evers, W.J.; Knaap, A. van der; Besselink, I.J.M.; Nijmeijer, H.

    2008-01-01

    A new design of variable geometry force actuator is presented in this paper. Based upon this design, a model is derived which is used for steady-state analysis, as well as controller design in the presence of friction. The controlled actuator model is finally used to evaluate the power consumption u

  7. Contribution of variable-speed wind turbines to voltage control

    Energy Technology Data Exchange (ETDEWEB)

    Ledesma, P.; Usaola, J.

    2003-07-01

    Variable speed, grid connected, wind turbines open new possibilities for voltage control, because they use electronic converters, which may regulate the reactive power interchange with the grid. This paper proposes two voltage control schemes for variable speed wind turbines with double-fed induction generator. The first scheme acts on the wind-turbine power factor, while the latter acts directly on the converter current. Advantages and draw backs of both techniques are discussed. Both control techniques have been tested by simulations of a base case, which represent a synchronous generator, a wind farm and a local load, and several disturbances such as the loss of compensator capacitors. (author)

  8. Overview of School and Unit Variables and Their Structural Relations in Phase I of the IGE Evaluation.

    Science.gov (United States)

    Price, Gary G.; And Others

    This document provides an overview of the school variables and unit variables used in Phase 1 of the Individually Guided Education (IGE) evaluation. Included in the discussion of each variable are a verbal definition of the variable, a description of the distribution of the variable in the 156 schools that participated in the Phase 1 study, and…

  9. Exporting Variables in a Hierarchically Distributed Control System

    Energy Technology Data Exchange (ETDEWEB)

    Chamizo Llatas, M.

    1995-07-01

    We describe the Remote Variable Access Service (RVAS), a network service developed and used in the distributed control and monitoring system of the TJ-II Heliac, which is under construction at CIEMAT (Madrid, Spain) and devoted to plasma studies in the nuclear fusion field. The architecture of the TJ-II control system consists of one central Sun workstation Sparc 10 and several autonomous subsystems based on VME crates with embedded processors running the OS-9 (V.24) real time operating system. The RVAS service allows state variables in local control processes running in subsystems to be exported to remote processes running in the central control workstation. Thus we extend the concept of exporting of file systems in UNIX machines to variables in processes running in different machines. (Author) 6 refs.

  10. Pitch Angle Control for Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhang, Jianzhong; Cheng, M;

    2008-01-01

    controller, the mathematical model of the system should be known well. A fuzzy logic pitch angle controller is developed in this paper, in which it does not need well known about the system and the mean wind speed is used to compensate the non-linear sensitivity. The fuzzy logic control strategy may have......Pitch angle control is the most common means for adjusting the aerodynamic torque of the wind turbine when wind speed is above rated speed and various controlling variables may be chosen, such as wind speed, generator speed and generator power. As conventional pitch control usually use PI...

  11. The Research and Application of Prediction Control in Multi-variable Control Process

    Institute of Scientific and Technical Information of China (English)

    WEI Shuangying

    2006-01-01

    The modern industrial control objects become more and more complicated, and higher control quality is required, so a series of new control strategies appear, applied, modified and develop quickly. This paper researches a new control strategy-prediction control-and its application in Multi-Variable Control Process. The research result is worthy for automatic control in process industry.

  12. Phase Dependent Spectral Variability of 4U1907+09

    CERN Document Server

    Roberts, M S E; Leahy, D A; Hall, T A; Finley, J P; Cominsky, L R; Srinivasan, R; Roberts, Mallory S.E.; Michelson, Peter F.; Leahy, Denis A.; Hall, Tony A.; Finley, John P.; Cominsky, Lynn R.; Srinivasen, Radhika

    2001-01-01

    We report on ASCA, RXTE, and archival observations of the high mass X-ray binary pulsar 4U1907+09. Spectral measurements of the absorption and flux were made at all phases of the X-ray pulsar orbit, including the first spectral measurements of an extended period of low flux during two of the ASCA observations. We find that a simple spherical wind model can fit the time averaged light curve as measured by the RXTE ASM, but does not fit the observed changes in the absorption column or account for the existence of the phase-locked secondary flare. An additional model component consisting of a trailing stream can account for the variations in column depth. However, these models favor a high inclination angle for the system, suggesting a companion mass more consistent with an identification as a Be-star. In this case an equatorially enhanced wind and inclined neutron star orbit may be a more appropriate interpretation of the data.

  13. Phase diagram of boron carbide with variable carbon composition

    Science.gov (United States)

    Yao, Sanxi; Gao, Qin; Widom, Michael

    2017-02-01

    Boron carbide exhibits intrinsic substitutional disorder over a broad composition range. The structure consists of 12-atom icosahedra placed at the vertices of a rhombohedral lattice, together with a 3-atom chain along the threefold axis. In the high-carbon limit, one or two carbon atoms can replace boron atoms on the icosahedra while the chains are primarily of type C-B-C. We fit an interatomic pair interaction model to density-functional-theory total energies to investigate the substitutional carbon disorder. Monte Carlo simulations with sampling improved by replica exchange and augmented by two-dimensional multiple histogram analysis predict three phases. The low-temperature, high-carbon-composition monoclinic C m structure disorders through a pair of phase transitions, first via an Ising-like transition to a monoclinic centrosymmetric state with space group C 2 /m , then via a first-order three-state Potts-like transition to the experimentally observed rhombohedral R 3 ¯m symmetry.

  14. Robust nonlinear variable selective control for networked systems

    Science.gov (United States)

    Rahmani, Behrooz

    2016-10-01

    This paper is concerned with the networked control of a class of uncertain nonlinear systems. In this way, Takagi-Sugeno (T-S) fuzzy modelling is used to extend the previously proposed variable selective control (VSC) methodology to nonlinear systems. This extension is based upon the decomposition of the nonlinear system to a set of fuzzy-blended locally linearised subsystems and further application of the VSC methodology to each subsystem. To increase the applicability of the T-S approach for uncertain nonlinear networked control systems, this study considers the asynchronous premise variables in the plant and the controller, and then introduces a robust stability analysis and control synthesis. The resulting optimal switching-fuzzy controller provides a minimum guaranteed cost on an H2 performance index. Simulation studies on three nonlinear benchmark problems demonstrate the effectiveness of the proposed method.

  15. Controlling Halo-Chaos via Variable Structure Method

    Institute of Scientific and Technical Information of China (English)

    方锦清; 于星火; 陈关荣

    2003-01-01

    We propose a variable structure control method which is another innovative technique for suppressing beam halochaos in the periodic focusing channels of high-current proton beam accelerator, which belongs to a high-tech field.The analysis and numerical results show that the method is effective for controlling beam halo-chaos. Physical implementation of such a kind of control strategy remains an important and open issue for further applications.

  16. Periodic radio variability in NRAO 530: phase dispersion minimization analysis

    Institute of Scientific and Technical Information of China (English)

    Jun-Chao Lu; Jun-Yi Wang; Tao An; Ji-Ming Lin; Hong-Bing Qiu

    2012-01-01

    A periodicity analysis of the radio light curves of the blazar NRAO 530 at 14.5,8.0,and 4.8 GHz is presented employing an improved phase dispersion minimization technique.The result,which shows two persistent periodic components of ~ 6 and ~ 10 yr at all three frequencies,is consistent with the results obtained with the Lomb-Scargle periodogram and weighted wavelet Z-transform algorithms.The reliability of the derived periodicities is confirmed by the Monte Carlo numerical simulations which show a high statistical confidence.(Quasi-)Periodic fluctuations of the radio luminosity of NRAO 530 might be associated with the oscillations of the accretion disk triggered by hydrodynamic instabilities of the accreted flow.

  17. Variable Structure PID Control to Prevent Integrator Windup

    Science.gov (United States)

    Hall, C. E.; Hodel, A. S.; Hung, J. Y.

    1999-01-01

    PID controllers are frequently used to control systems requiring zero steady-state error while maintaining requirements for settling time and robustness (gain/phase margins). PID controllers suffer significant loss of performance due to short-term integrator wind-up when used in systems with actuator saturation. We examine several existing and proposed methods for the prevention of integrator wind-up in both continuous and discrete time implementations.

  18. Evaluation of the Phase-Dependent Rhythm Control of Human Walking Using Phase Response Curves.

    Directory of Open Access Journals (Sweden)

    Tetsuro Funato

    2016-05-01

    Full Text Available Humans and animals control their walking rhythms to maintain motion in a variable environment. The neural mechanism for controlling rhythm has been investigated in many studies using mechanical and electrical stimulation. However, quantitative evaluation of rhythm variation in response to perturbation at various timings has rarely been investigated. Such a characteristic of rhythm is described by the phase response curve (PRC. Dynamical simulations of human skeletal models with changing walking rhythms (phase reset described a relation between the effective phase reset on stability and PRC, and phase reset around touch-down was shown to improve stability. A PRC of human walking was estimated by pulling the swing leg, but such perturbations hardly influenced the stance leg, so the relation between the PRC and walking events was difficult to discuss. This research thus examines human response to variations in floor velocity. Such perturbation yields another problem, in that the swing leg is indirectly (and weakly perturbed, so the precision of PRC decreases. To solve this problem, this research adopts the weighted spike-triggered average (WSTA method. In the WSTA method, a sequential pulsed perturbation is used for stimulation. This is in contrast with the conventional impulse method, which applies an intermittent impulsive perturbation. The WSTA method can be used to analyze responses to a large number of perturbations for each sequence. In the experiment, perturbations are applied to walking subjects by rapidly accelerating and decelerating a treadmill belt, and measured data are analyzed by the WSTA and impulse methods. The PRC obtained by the WSTA method had clear and stable waveforms with a higher temporal resolution than those obtained by the impulse method. By investigation of the rhythm transition for each phase of walking using the obtained PRC, a rhythm change that extends the touch-down and mid-single support phases is found to occur.

  19. Evaluation of the Phase-Dependent Rhythm Control of Human Walking Using Phase Response Curves.

    Science.gov (United States)

    Funato, Tetsuro; Yamamoto, Yuki; Aoi, Shinya; Imai, Takashi; Aoyagi, Toshio; Tomita, Nozomi; Tsuchiya, Kazuo

    2016-05-01

    Humans and animals control their walking rhythms to maintain motion in a variable environment. The neural mechanism for controlling rhythm has been investigated in many studies using mechanical and electrical stimulation. However, quantitative evaluation of rhythm variation in response to perturbation at various timings has rarely been investigated. Such a characteristic of rhythm is described by the phase response curve (PRC). Dynamical simulations of human skeletal models with changing walking rhythms (phase reset) described a relation between the effective phase reset on stability and PRC, and phase reset around touch-down was shown to improve stability. A PRC of human walking was estimated by pulling the swing leg, but such perturbations hardly influenced the stance leg, so the relation between the PRC and walking events was difficult to discuss. This research thus examines human response to variations in floor velocity. Such perturbation yields another problem, in that the swing leg is indirectly (and weakly) perturbed, so the precision of PRC decreases. To solve this problem, this research adopts the weighted spike-triggered average (WSTA) method. In the WSTA method, a sequential pulsed perturbation is used for stimulation. This is in contrast with the conventional impulse method, which applies an intermittent impulsive perturbation. The WSTA method can be used to analyze responses to a large number of perturbations for each sequence. In the experiment, perturbations are applied to walking subjects by rapidly accelerating and decelerating a treadmill belt, and measured data are analyzed by the WSTA and impulse methods. The PRC obtained by the WSTA method had clear and stable waveforms with a higher temporal resolution than those obtained by the impulse method. By investigation of the rhythm transition for each phase of walking using the obtained PRC, a rhythm change that extends the touch-down and mid-single support phases is found to occur.

  20. Reasoning about Multiple Variables: Control of Variables Is Not the Only Challenge

    Science.gov (United States)

    Kuhn, Deanna

    2007-01-01

    Thirty fourth-grade students participated in an extended intervention previously successful in fostering skills of scientific investigation and inference, notably control of variables (COV). The intervention was similarly successful for a majority of students in the present study, enabling them to isolate the three causal and two noncausal…

  1. Partially dark optical molecule via phase control

    Science.gov (United States)

    Wang, Z. H.; Xu, Xun-Wei; Li, Yong

    2017-01-01

    We study the tunable photonic distribution in an optical molecule consisting of two linearly coupled single-mode cavities. With the intercavity coupling and two driving fields, the energy levels of the optical-molecule system form a closed cyclic energy-level diagram, and the phase difference between the driving fields serves as a sensitive controller on the dynamics of the system. Due to the quantum interference effect, we can realize a partially dark optical molecule, where the steady-state mean photon number in one of the cavities achieves zero even under the external driving. And the dark cavity can be changed from one of the cavities to the other by only adjusting the phase difference. We also show that our proposal is robust to the noise at zero temperature. Furthermore, we show that when one of the cavities couples with an atomic ensemble, it will be dark under the same condition as that in the case without atoms, but the condition for the other cavity to be dark is modified.

  2. Ionization cross section for a strongly coupled partially ionized hydrogen plasma: variable phase approach

    Energy Technology Data Exchange (ETDEWEB)

    Baimbetov, F B; Kudyshev, Z A [Department of Physics, Al-Farabi Kazakh National University, 050012 Almaty (Kazakhstan)], E-mail: Fazylhan.Baimbetov@kaznu.kz, E-mail: Z.Kudyshev@mail.ru

    2009-05-29

    In the present work an electron impact ionization cross section is considered. The electron impact ionization cross section is calculated with the help of a variable phase approach to potential scattering. The Calogero equation is numerically solved, based on a pseudopotential model of interaction between partially ionized plasma particles, which accounts for correlation effects. As a result, scattering phase shifts are obtained. On the basis of the scattering phase shifts, the ionization cross section is calculated.

  3. Variable Structure Control of Catastrophic Course in Airdropping Heavy Cargo

    Institute of Scientific and Technical Information of China (English)

    Zhang Huiyuan; Shi Zhongke

    2009-01-01

    The mathematical model of a transport aircraft would be subjected to a sudden change when heavy cargo is dropped off in airdropping, which exerts serious influences upon the safety of the aircraft. A variable structure controller is specially designed for handling the airdrop process. The nonlinear system is linearized by input-output feedback linearization using differential geometry theories. On this basis, an inner loop system for velocity and attitude tracking control is designed by using the exponentially approaching rule of the variable structure theory. The whole flight control system is integrated with the outer loop flight altitude control. Digital simulation evidences the applicability of the system to potentially catastrophic course in airdropping heavy cargo and provides robustness against system parameter perturbation.

  4. Hillslope characteristics as controls of subsurface flow variability

    Directory of Open Access Journals (Sweden)

    S. Bachmair

    2012-06-01

    Full Text Available Hillslope hydrological dynamics, particularly subsurface flow (SSF, are highly variable and complex. A profound understanding of factors controlling this variability is needed. Therefore we investigated the relationship between variability of shallow water table dynamics and various hillslope characteristics. We ask whether measurable hillslope properties explain patterns of subsurface flow variability. To approach this question shallow water table dynamics of three adjacent large-scale hillslopes were monitored with high spatial and temporal resolution over 18 months. The hillslopes are similar in terms of topography and parent material, but different in vegetation cover (grassland, coniferous forest, and mixed forest. We expect vegetation to be an important driver of water table dynamics at our study site, especially given the minor differences in topography. Various hillslope properties were determined in the field and via GIS analysis: common topography descriptors, well depth, soil properties via slug tests, and several vegetation parameters. Response variables characterizing the water table response per well were calculated for different temporal scales (entire time series, seasonal scale, event scale. Partial correlation analysis and a Random Forest machine learning approach were carried out to assess the explainability of SSF variability by measurable hillslope characteristics. We found a complex interplay of predictors, yet soil properties and topography showed the highest single explanatory power. Surprisingly, vegetation characteristics played a minor role. Solely throughfall and canopy cover exerted a slightly stronger control, especially in summer. Most importantly, the examined hillslope characteristics explained only a small proportion of the observed SSF variability. Consequently there must be additional important drivers not represented by current measurement techniques of the hillslope configuration (e.g. bedrock properties

  5. Hillslope characteristics as controls of subsurface flow variability

    Science.gov (United States)

    Bachmair, S.; Weiler, M.

    2012-10-01

    Hillslope hydrological dynamics, particularly subsurface flow (SSF), are highly variable and complex. A profound understanding of factors controlling this variability is needed. Therefore we investigated the relationship between variability of shallow water table dynamics and various hillslope characteristics. We ask whether measurable hillslope properties explain patterns of subsurface flow variability. To approach this question, shallow water table dynamics of three adjacent large-scale hillslopes were monitored with high spatial and temporal resolution over 18 months. The hillslopes are similar in terms of topography and parent material, but different in vegetation cover (grassland, coniferous forest, and mixed forest). We expect vegetation to be an important driver of water table dynamics at our study site, especially given the minor differences in topography. Various hillslope properties were determined in the field and via GIS analysis: common topography descriptors, well depth, soil properties via slug tests, and several vegetation parameters. Response variables characterizing the water table response per well were calculated for different temporal scales (entire time series, seasonal scale, event scale). Partial correlation analysis and a Random Forest machine learning approach were carried out to assess the explainability of SSF variability by measurable hillslope characteristics. We found a complex interplay of predictors, yet soil properties and topography showed the highest single explanatory power. Surprisingly, vegetation characteristics played a minor role. Solely throughfall and canopy cover exerted a slightly stronger control, especially in summer. Most importantly, the examined hillslope characteristics explained only a small proportion of the observed SSF variability. Consequently there must be additional important drivers not represented by current measurement techniques of the hillslope configuration (e.g. bedrock properties, preferential

  6. Hillslope characteristics as controls of subsurface flow variability

    Directory of Open Access Journals (Sweden)

    S. Bachmair

    2012-10-01

    Full Text Available Hillslope hydrological dynamics, particularly subsurface flow (SSF, are highly variable and complex. A profound understanding of factors controlling this variability is needed. Therefore we investigated the relationship between variability of shallow water table dynamics and various hillslope characteristics. We ask whether measurable hillslope properties explain patterns of subsurface flow variability. To approach this question, shallow water table dynamics of three adjacent large-scale hillslopes were monitored with high spatial and temporal resolution over 18 months. The hillslopes are similar in terms of topography and parent material, but different in vegetation cover (grassland, coniferous forest, and mixed forest. We expect vegetation to be an important driver of water table dynamics at our study site, especially given the minor differences in topography. Various hillslope properties were determined in the field and via GIS analysis: common topography descriptors, well depth, soil properties via slug tests, and several vegetation parameters. Response variables characterizing the water table response per well were calculated for different temporal scales (entire time series, seasonal scale, event scale. Partial correlation analysis and a Random Forest machine learning approach were carried out to assess the explainability of SSF variability by measurable hillslope characteristics. We found a complex interplay of predictors, yet soil properties and topography showed the highest single explanatory power. Surprisingly, vegetation characteristics played a minor role. Solely throughfall and canopy cover exerted a slightly stronger control, especially in summer. Most importantly, the examined hillslope characteristics explained only a small proportion of the observed SSF variability. Consequently there must be additional important drivers not represented by current measurement techniques of the hillslope configuration (e.g. bedrock properties

  7. Ocean versus atmosphere control on western European wintertime temperature variability

    Science.gov (United States)

    Yamamoto, Ayako; Palter, Jaime B.; Lozier, M. Susan; Bourqui, Michel S.; Leadbetter, Susan J.

    2015-12-01

    Using a novel Lagrangian approach, we assess the relative roles of the atmosphere and ocean in setting interannual variability in western European wintertime temperatures. We compute sensible and latent heat fluxes along atmospheric particle trajectories backtracked in time from four western European cities, using a Lagrangian atmospheric dispersion model driven with meteorological reanalysis data. The material time rate of change in potential temperature and the surface turbulent fluxes computed along the trajectory show a high degree of correlation, revealing a dominant control of ocean-atmosphere heat and moisture exchange in setting heat flux variability for atmospheric particles en route to western Europe. We conduct six idealised simulations in which one or more aspects of the climate system is held constant at climatological values and these idealised simulations are compared with a control simulation, in which all components of the climate system vary realistically. The results from these idealised simulations suggest that knowledge of atmospheric pathways is essential for reconstructing the interannual variability in heat flux and western European wintertime temperature, and that variability in these trajectories alone is sufficient to explain at least half of the internannual flux variability. Our idealised simulations also expose an important role for sea surface temperature in setting decadal scale variability of air-sea heat fluxes along the Lagrangian pathways. These results are consistent with previous studies showing that air-sea heat flux variability is driven by the atmosphere on interannual time scales over much of the North Atlantic, whereas the SST plays a leading role on longer time scales. Of particular interest is that the atmospheric control holds for the integrated fluxes along 10-day back trajectories from western Europe on an interannual time scale, despite that many of these trajectories pass over the Gulf Stream and its North Atlantic

  8. Speed Control of Induction Motor by Using Variable Frequency

    OpenAIRE

    Drive Pooja Shinde; Rupali Burungale

    2014-01-01

    The variable speed drive is focused on voltage amplitude control. However, its only control speed in constraint limits. The load on Induction Motor is not constant & vary as per load requirement. so speed must be change as per load. If the supply voltage decreased motor torque also decreases, for maintaining same torque, slip decreases hence speed falls and motor speed is directly proportional to supply frequency, hence to maintain a speed, the supply V/F ratio must be vary ac...

  9. Variable-thermoinsulation garments with a microprocessor temperature controller.

    Science.gov (United States)

    Kurczewska, Agnieszka; Leánikowski, Jacek

    2008-01-01

    This paper presents the concept of active variable thermoinsulation clothing for users working in low temperatures. Those garments contain heating inserts regulated by a microprocessor temperature controller. This paper also presents the results of tests carried out on the newly designed garments.

  10. Closed-Loop Control of MEMS Variable Optical Attenuator (VOA)

    Institute of Scientific and Technical Information of China (English)

    H.Cai; X.; M.; Zhang; A.; Q.; Liu; Y.; X.; Wang; C.; Lu

    2003-01-01

    This paper reports the development of an optical power regulator based on surface-micromachined variable optical attenuators (VOAs). By use of closed-loop control circuits, each VOA module implements the functions of power setpoint tracking, disturbance rejection and ripple suppression.

  11. Control Method for Variable Speed Wind Turbines to Support Temporary Primary Frequency Control

    DEFF Research Database (Denmark)

    Wang, Haijiao; Chen, Zhe; Jiang, Quanyuan

    2014-01-01

    This paper develops a control method for variable speed wind turbines (VSWTs) to support temporary primary frequency control of power system. The control method contains two parts: (1) up-regulate support control when a frequency drop event occurs; (2) down-regulate support control when a frequen...

  12. Pwm Control Strategy For Controlling Of Parallel Rectifiers In Single Phase To Three Phase Drive System

    Directory of Open Access Journals (Sweden)

    Ramakrishna Manohar Anaparthi

    2014-12-01

    Full Text Available This paper explains that how to develop and design, control of single phase to three phase drive system. The proposed topology of drive system consisting of two parallel connected rectifiers, inverter and induction motor, connected through inductor and capacitor, where used to produce balanced output to the motor drive. The main objective of this proposed method is to reduce the circulating currents and harmonic distortions at the converter input side, here the control strategy of drive system is PWM (pulse width modulations techniques control strategy, the proposed topology also provides fault compensation in the case of short circuit faults and failure of switches for uninterrupted Power supplies. We also develop and simulate the MATLAB models for proposed drive system, by using MATLAB/ Simulink the output results simulate and observed.

  13. Phase control system concepts and simulations. [solar power satellite system

    Science.gov (United States)

    Lindsay, V. C.

    1980-01-01

    A phase control system concept for a solar power satellite is proposed which partitions the system into three major levels. The first level of phase control consists of a reference phase distribution system implemented in the form of phase distribution tree structure. The major purpose of the tree structure is to electronically compensate for the phase shift due to the transition path lengths from the center of the spacetenna to each phase control center located in each subarray. In the reference system, this is accomplished using the master slave returnable timing system technique. The second level of phase control consists of the beam steering and microwave power generating system which houses the power transponders. This transponder consists of a set of phase conjugation multipliers driven by the reference phase distribution system output and the output of a pilot spread spectrum receiver which accepts the received pilot via a diplexer connected to a separate receive horn or the subarray itself. The output of the phase conjugation circuits serve as inputs to the third level of the phase control system. The third level of phase control is associated with maintaining an equal and constant phase shift through the microwave power amplifier devices while minimizing the associated phase noise effects on the generated power beam. This is accomplished by providing a phase locked loop around each high power amplifier.

  14. Combined variable speed/variable pitch controlled 3-bladed wind turbine; Dobbelt styrbar 3-bladet vindmoelle

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-10-01

    The final report describes the results from EFP-96 project `Combined variable speed/variable pitch controlled 3-bladed wind turbine`. Included in the investigation are assessments of the power production, the power quality and structural loads on the wind turbine. The project includes both theoretical and experimental investigations. The test facility consists of a Vestas V29-225 kW wind turbine with a Sami Star 400 kVA frequency converter from ABB. The conclusion is that a concept of one V29 and one Sami Star frequency converter to a variable speed is not relevant for marketing. But the concept can be relevant if the frequency converter is replaced by a frequency converter with higher switch frequency. (EHS)

  15. Variable structure control of complex systems analysis and design

    CERN Document Server

    Yan, Xing-Gang; Edwards, Christopher

    2017-01-01

    This book systematizes recent research work on variable-structure control. It is self-contained, presenting necessary mathematical preliminaries so that the theoretical developments can be easily understood by a broad readership. The text begins with an introduction to the fundamental ideas of variable-structure control pertinent to their application in complex nonlinear systems. In the core of the book, the authors lay out an approach, suitable for a large class of systems, that deals with system uncertainties with nonlinear bounds. Its treatment of complex systems in which limited measurement information is available makes the results developed convenient to implement. Various case-study applications are described, from aerospace, through power systems to river pollution control with supporting simulations to aid the transition from mathematical theory to engineering practicalities. The book addresses systems with nonlinearities, time delays and interconnections and considers issues such as stabilization, o...

  16. Single step optimization of manipulator maneuvers with variable structure control

    Science.gov (United States)

    Chen, N.; Dwyer, T. A. W., III

    1987-01-01

    One step ahead optimization has been recently proposed for spacecraft attitude maneuvers as well as for robot manipulator maneuvers. Such a technique yields a discrete time control algorithm implementable as a sequence of state-dependent, quadratic programming problems for acceleration optimization. Its sensitivity to model accuracy, for the required inversion of the system dynamics, is shown in this paper to be alleviated by a fast variable structure control correction, acting between the sampling intervals of the slow one step ahead discrete time acceleration command generation algorithm. The slow and fast looping concept chosen follows that recently proposed for optimal aiming strategies with variable structure control. Accelerations required by the VSC correction are reserved during the slow one step ahead command generation so that the ability to overshoot the sliding surface is guaranteed.

  17. Considering Variable Road Geometry in Adaptive Vehicle Speed Control

    Directory of Open Access Journals (Sweden)

    Xinping Yan

    2013-01-01

    Full Text Available Adaptive vehicle speed control is critical for developing Advanced Driver Assistance Systems (ADAS. Vehicle speed control considering variable road geometry has become a hotspot in ADAS research. In this paper, first, an exploration of intrinsic relationship between vehicle operation and road geometry is made. Secondly, a collaborative vehicle coupling model, a road geometry model, and an AVSC, which can respond to variable road geometry in advance, are developed. Then, based on H∞ control method and the minimum energy principle, a performance index is specified by a cost function for the proposed AVSC, which can explicitly consider variable road geometry in its optimization process. The proposed AVSC is designed by the Hamilton-Jacobi Inequality (HJI. Finally, simulations are carried out by combining the vehicle model with the road geometry model, in an aim of minimizing the performance index of the AVSC. Analyses of the simulation results indicate that the proposed AVSC can automatically and effectively regulate speed according to variable road geometry. It is believed that the proposed AVSC can be used to improve the economy, comfort, and safety effects of current ADAS.

  18. An Approach to Discrete Variable Structure Control System

    Institute of Scientific and Technical Information of China (English)

    FalahE.Alsaqre; YUANBaozong

    2003-01-01

    Variable structure control (VSC) systems consist of a set of subsystems referred to as structures and supplied with appropriate switching functions. The most common approach used for variable structure in continu-ous or discrete time systems is sliding mode. In this paper,a new scheme to design a discrete variable structure con-trol (DVSC) for an nth-order type one system is presented.First, a set of discrete subsystems is constructed relying on the assumption that every system is considered as a vari-able structure system when its poles can be assignment to other locations. The adopted method for constructing dif-ferent discrete structures involves switching alternatively two zero-order hold (ZOH) devices, having different char-acteristics. Second, a suitable switching function is devised based on minimizing a quadratic sum of discrete error sig-nal criterion, to perform one switching without chattering.New advantageous properties are carried out via compos-ing a desired performance from parts of performances of the constructed structures. Simulation results are made to illustrate the quality of control being achieved.

  19. RBCC可重复使用运载器上升段轨迹优化设计%Since the multi-phase and multi-control-variable trajectory of the reusable launch vehicle ( RLV) which is coupled with the thrust powered by rocket based combined cycle (RBCC) is difficult to solve,the numerical optimization model and method based on Gau

    Institute of Scientific and Technical Information of China (English)

    龚春林; 韩璐

    2012-01-01

    Since the multi-phase and multi-control-variable trajectory of the reusable launch vehicle ( RLV) which is coupled with the thrust powered by rocket based combined cycle (RBCC) is difficult to solve,the numerical optimization model and method based on Gauss Pseudospectral Method (CPM) were proposed,and the optimal-fuel ascent trajectory was obtained. Hie trajectory is divided into three phases powered by rocket,ramjet and scramjet in sequence. The angle of attack and fuel flow are control variables,and according to the trajectory mission,the ignition and work condition of the each mode,the optimization model was built,the terminal and path constraints were imposed. The optimal trajectory was solved by using GPM and the boundary control variables were solved by a special method. Compared with the result by traditional method,the optimization model and GPM can solve trajectory optimization problems effectively, and the optimal result accords with the characteristic of the RBCC-powered RLV and satisfies all the constraints.%针对火箭基组合动力(RBCC)可重复使用运载器(RLV)轨迹多段、多控制变量、推力与飞行轨迹耦合,飞行轨迹设计困难的问题,提出了基于高斯伪光谱方法的数值优化求解模型和求解方法,并获得满足要求的上升段燃料最省轨迹.将该轨迹分为3部分,分别由引射火箭、亚燃冲压和超燃冲压发动机提供动力,以攻角和燃料秒流量为控制变量,根据轨迹任务和各模态发动机启动及工作条件建立优化模型、设定各段末端和路径约束,利用高斯伪谱法求解最优轨迹并利用特殊方法计算边界控制变量.通过与传统方法所得轨迹的对比表明,所建立的优化模型和方法可快速求解出RBCC运载器上升段最优轨迹,优化结果符合RBCC运载器工作特点.

  20. Control design variable linking for optimization of structural/control systems

    Science.gov (United States)

    Jin, Ik Min; Schmit, Lucien A.

    1993-01-01

    A method is presented to integrate the design space of structural/control system optimization problems in the case of linear state feedback control. Conventional structural sizing variables and elements of the feedback gain matrix are both treated as strictly independent design variables in optimization by extending design variable linking concepts to the control gains. Several approximation concepts including new control design variable linking schemes are used to formulate the integrated structural/control optimization problem as a sequence of explicit nonlinear mathematical programming problems. Examples which involve a variety of behavior constraints, including constraints on dynamic stability, damped frequencies, control effort, peak transient displacement, acceleration, and control force limits, are effectively solved by using the method presented.

  1. Automatic phase control in solar power satellite systems

    Science.gov (United States)

    Lindsey, W. C.; Kantak, A. V.

    1978-01-01

    Various approaches to the problem of generating, maintaining and distributing a coherent, reference phase signal over a large area are suggested, mathematically modeled and analyzed with respect to their ability to minimize: phase build-up, beam diffusion and beam steering phase jitter, cable length, and maximize power transfer efficiency. In addition, phase control configurations are suggested which alleviate the need for layout symmetry.

  2. Variable structure control for maximum wind power extraction

    Energy Technology Data Exchange (ETDEWEB)

    Barambones, O.; Gonzalez de Durana, J.M.; Alcorta, P. [Univ. of the Basque Country, Vitoria (Spain)

    2009-07-01

    The future development of wind power technology will affect the level of impact that wind power will have on the power system. Very large wind farms can pose complex technical challenges while also paving the way for other new technologies that will help with electric grid integration. Increasingly complicated power electronic and computerized control schemes will lead to significant improvements and full controllability of available wind power. Reactive power compensation is an important issue in the control of distribution and transmission systems as it increases feeder system losses, reduces system power factor, and can cause large-amplitude variations in load-side voltage. Moreover, rapid changes in the reactive power consumption of large load centers can cause voltage amplitude oscillations, leading to a change in the electric system real power demand resulting in power oscillation. This paper described a sliding mode vector control for a double fed induction generator (DFIG) drive, used in variable speed wind power generation. The study proposed a new variable structure control which has an integral sliding surface to relax the requirement of the acceleration signal, commonly used in conventional sliding mode speed control techniques. The paper discussed the system modelling, DFIG control scheme, and simulation results. A test of the proposed method based on a two-bladed horizontal axis wind turbine was conducted using the Matlab/Simulink software. In this test, several operating conditions were simulated and the study concluded that satisfactory results were obtained. 14 refs., 5 figs.

  3. Economic Statistical Design of Variable Sampling Interval X¯$\\overline X $ Control Chart Based on Surrogate Variable Using Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Lee Tae-Hoon

    2016-12-01

    Full Text Available In many cases, a X¯$\\overline X $ control chart based on a performance variable is used in industrial fields. Typically, the control chart monitors the measurements of a performance variable itself. However, if the performance variable is too costly or impossible to measure, and a less expensive surrogate variable is available, the process may be more efficiently controlled using surrogate variables. In this paper, we present a model for the economic statistical design of a VSI (Variable Sampling Interval X¯$\\overline X $ control chart using a surrogate variable that is linearly correlated with the performance variable. We derive the total average profit model from an economic viewpoint and apply the model to a Very High Temperature Reactor (VHTR nuclear fuel measurement system and derive the optimal result using genetic algorithms. Compared with the control chart based on a performance variable, the proposed model gives a larger expected net income per unit of time in the long-run if the correlation between the performance variable and the surrogate variable is relatively high. The proposed model was confined to the sample mean control chart under the assumption that a single assignable cause occurs according to the Poisson process. However, the model may also be extended to other types of control charts using a single or multiple assignable cause assumptions such as VSS (Variable Sample Size X¯$\\overline X $ control chart, EWMA, CUSUM charts and so on.

  4. Electric field controlled emulsion phase contactor

    Science.gov (United States)

    Scott, Timothy C.

    1995-01-01

    A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

  5. Variable structure attitude maneuver and vibration control of flexible spacecraft

    Institute of Scientific and Technical Information of China (English)

    HU Qing-lei; MA Cuang-fu

    2008-01-01

    A dual-stage control system design method is presented for the three-axis-rotational maneuver and vibration stabilization of a spacecraft with flexible appendages embedded with piezoceramics as sensor and actuator.In this design approach,the attitude control and the vibration suppression sub-systems ale designed separately using the lower order model.The design of attitude controller is based on the variable structure control (VSC)theory leading to a discontinuous control law.This controller accomplishes asymptotic attitude maneuvering in the closed-loop system and is insensitive to the interaction of elastic modes and uncertainty in the system.To actively suppress the flexible vibrations,the modal velocity feedback control method is presented by using piezoelectric materials as additional sensor and actuator bonded on the surface of the flexible appendages.In addition,a special configuration of actuators for three-axis attitude control is also investigated:the pitch attitude controlled by a momentum wheel,and the roll/yaw control achieved by on-off thrustem.which is modulated by pulse width pulse frequency modulation technique to construct the proper control torque history.Numerical simulations performed show that the rotational maneuver and vibration suppression ale accomplished in spite of the presence of disturbance torque and parameter uncertainty.

  6. Singularly perturbed control systems with noncompact fast variable

    Science.gov (United States)

    Nguyen, Thuong; Siconolfi, Antonio

    2016-10-01

    We deal with a singularly perturbed optimal control problem with slow and fast variable depending on a parameter ε. We study the asymptotics, as ε goes to 0, of the corresponding value functions, and show convergence, in the sense of weak semilimits, to sub and supersolution of a suitable limit equation containing the effective Hamiltonian. The novelty of our contribution is that no compactness condition is assumed on the fast variable. This generalization requires, in order to perform the asymptotic procedure, an accurate qualitative analysis of some auxiliary equations posed on the space of fast variable. The task is accomplished using some tools of Weak KAM theory, and in particular the notion of Aubry set.

  7. Variable selection with error control: Another look at Stability Selection

    CERN Document Server

    Shah, Rajen

    2011-01-01

    Stability Selection was recently introduced by Meinshausen and Buhlmann (2010) as a very general technique designed to improve the performance of a variable selection algorithm. It is based on aggregating the results of applying a selection procedure to subsamples of the data. We introduce a variant, called Complementary Pairs Stability Selection (CPSS), and derive bounds both on the expected number of variables included by CPSS that have low selection probability under the original procedure, and on the expected number of high selection probability variables that are excluded. These results require no (e.g. exchangeability) assumptions on the underlying model or on the quality of the original selection procedure. Under reasonable shape restrictions, the bounds can be further tightened, yielding improved error control, and therefore increasing the applicability of the methodology.

  8. A High Efficiency Variable Gain Amplifier Circuit with Controllable Transconductance Amp

    Science.gov (United States)

    Okura, Tetsuro; Okura, Shunsuke; Ido, Toru; Taniguchi, Kenji

    A novel power reduction technique for a variable gain amplifier (VGA) with a two-stage operational amplifier is proposed. The technique improves the power consumption of a VGA by optimizing the bandwidth and the phase margin dynamically on all gain range of the VGA through controlling the input transconductance of opamp. A VGA utilizing the proposed technique shows 40% reduction of power consumption against a conventional VGA at the best condition of VGA gain range.

  9. Performance Analysis of Phase Controlled Unidirectional and Bidirectional AC Voltage Controllers

    Directory of Open Access Journals (Sweden)

    Abdul Sattar Larik

    2011-01-01

    Full Text Available AC voltage controllers are used to vary the output ac voltage from a fixed ac input source. They are also commonly called ac voltage regulators or ac choppers. The output voltage is either controlled by PAC (Phase Angle Control method or on-off control method. Due to various advantages of ac voltage controllers, such as high efficiency, simplicity, low cost and ability to control large amount of power they efficiently control the speed of ac motors, light dimming and industrial heating, etc. These converters are variable structure systems and generate harmonics during the operation which will affect the power quality when connected to system network. During the last couple of years, a number of new semiconductor devices and various power electronic converters has been introduced. Accordingly the subject of harmonics and its problems are of great concern to power industry and customers. In this research work, initially the simulation models of single phase unidirectional and bidirectional ac voltage controllers were developed by using MATLAB software. The harmonics of these models are investigated by simulation. In the end, the harmonics were also analyzed experimentally. The simulated as well as experimental results are presented.

  10. Power system integration and control of variable speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Eek, Jarle

    2009-12-15

    A wind power plant is a highly dynamic system that dependent on the type of technology requires a number of automatic control loops. This research deals with modelling, control and analysis related to power system integration of variable speed, pitch controlled wind turbines. All turbine components have been modelled and implemented in the power system simulation program SIMPOW, and a description of the modelling approach for each component is given. The level of model detail relates to the classical modelling of power system components for power system stability studies, where low frequency oscillations are of special importance. The wind turbine model includes a simplified representation of the developed rotor torque and the thrust force based on C{sub p-} and C{sub t} characteristic curves. The mechanical system model represents the fundamental torsional mode and the first mode of blades and tower movements. Two generator technologies have been investigated. The doubly fed induction generator (DFIG) and the stator converter interfaced permanent magnet synchronous generator (PMSG). A simplified model of a 2 level voltage source converter is used for both machine types. The generator converter controllers have been given special attention. All model components are linearized for the purpose of control system design and power system interaction related to small signal stability analysis. Different control strategies discussed in the literature have been investigated with regard to power system interaction aspects. All control parameters are identified using the internal model control approach. The analysis is focused on three main areas: 1. Identification of low damped oscillatory modes. This is carried out by the establishment and discussion of wind turbine modelling. 2. Interaction between control loops. A systematic approach is presented in order to analyse the influence of control loops used in variable speed wind turbines. 3.Impact on power system performance

  11. An Adaptive Variable Structure Control Scheme for Underactuated Mechanical Manipulators

    Directory of Open Access Journals (Sweden)

    Jung Hua Yang

    2012-01-01

    Full Text Available Mechanical arms have been widely used in the industry for many decades. They have played a dominant role in factory automation. However the control performance, or even system stability, would be deteriorated if some of the actuators fail during the operations. Hence, in this study, an adaptive variable structure scheme is presented to solve this problem. It is shown that, by applying the control mechanism proposed in this paper, the motion of robot systems can maintain asymptotical stability in case of actuators failure. The control algorithms as well as the convergence analysis are theoretically proved based on Lyapunov theory. In addition, to demonstrate the validity of the controller, a number of simulations as well as real-time experiments are also performed for Pendubot robot and Furuta robot systems. The results confirm the applicability of the proposed controller.

  12. Pitch Angle Control of Variable Speed Wind Turbine

    Directory of Open Access Journals (Sweden)

    Yousif El-Tous

    2008-01-01

    Full Text Available The aim of this study is to design a simple controller to maximize the extracted energy of wind turbines. In this study the pitch angle control of variable speed wind turbine is investigated. In particular, it concentrates on the extraction of maximum available energy, reduction of torque and output power variations, which gives stresses in the gearbox and mechanical structure. The control concentrates on separate wind speed internals as well as on whole wind speed region. It is found that the control structures varies substantially between the wind speed regions. Two different control systems are compared. The results show that pitch actuator with three levels of pitching speed have better response.

  13. Variable structure control of nonlinear systems through simplified uncertain models

    Science.gov (United States)

    Sira-Ramirez, Hebertt

    1986-01-01

    A variable structure control approach is presented for the robust stabilization of feedback equivalent nonlinear systems whose proposed model lies in the same structural orbit of a linear system in Brunovsky's canonical form. An attempt to linearize exactly the nonlinear plant on the basis of the feedback control law derived for the available model results in a nonlinearly perturbed canonical system for the expanded class of possible equivalent control functions. Conservatism tends to grow as modeling errors become larger. In order to preserve the internal controllability structure of the plant, it is proposed that model simplification be carried out on the open-loop-transformed system. As an example, a controller is developed for a single link manipulator with an elastic joint.

  14. Control of entity interactions in a hierarchical variable resolution simulation

    Energy Technology Data Exchange (ETDEWEB)

    Powell, D.R.

    1997-10-01

    There has long been interest in variable resolution modeling to support military analysis for a broad range of interest areas. Despite the ever-present desire for models of greater fidelity at the expense of analysis and computation resources, models of moderate to low fidelity are still required at many levels of decision-making. Problems can arise due to the issue of consistency among the family of models used for analysis. To address this and other problems, models of variable resolution have been suggested. However, such variable resolution architectures inherently carry their own set of issues which must be resolved in order to be useful. First, what are the structural requirements for a variable resolution model; and second, how are interactions between entities governed, especially when the entities have different resolutions? This paper addresses these issues and discusses key mechanisms needed to develop a variable resolution combat simulation that meets several core requirements for such models: seamless aggregation/disaggregation, appropriate interactions between entities of differing resolution, and control of the aggregation/disaggregation process.

  15. Control of entity interactions in a hierarchical variable resolution simulation

    Energy Technology Data Exchange (ETDEWEB)

    Powell, D.R.

    1997-08-01

    There has long been interest in variable resolution modeling to support military analysis for a broad range of interest areas. Despite the ever-present desire for models of greater fidelity at the expense of analysis and computation resources, models of moderate to low fidelity are still required at many levels of decision-making. Problems can arise due to the issue of consistency among the family of models used for analysis. To address this and other problems, models of variable resolution have been suggested. However, such variable resolution architectures inherently carry their own set of issues which must be resolved in order to be useful. First, what are the structural requirements for a variable resolution model; and second, how are interactions between entities governed, especially when the entities have different resolutions? This paper addresses these issues and discusses key mechanisms needed to develop a variable resolution combat simulation that meets several core requirements for such models: seamless aggregation/disaggregation, appropriate interactions between entities of differing resolution, and control of the aggregation/disaggregation process.

  16. A PAC Based Current Feedforward Control for Three-Phase PWM Voltage-Type Converter

    Institute of Scientific and Technical Information of China (English)

    屈克庆; 陈国呈; 孙承波

    2004-01-01

    This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC). With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed. For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle. Also, the algorithm is derived and the system principle is introduced. Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.

  17. Control Chaos in Hindmarsh-Rose Neuron by Using Intermittent Feedback with One Variable

    Institute of Scientific and Technical Information of China (English)

    MA Jun; WANG Qing-Yun; JIN Wu-Yin; XIA Ya-Feng

    2008-01-01

    The mechanism of the famous phase compression is discussed, and it is used to control the chaos in the Hindmarsh-Rose (H-R) model. It is numerically confirmed that the phase compression scheme can be understood as one kind of intermittent feedback scheme, which requires appropriate thresholds and feedback coefficient, and the intermittent feedback can be realized with the Heaviside function. In the case of control chaos, the output variable (usually the voltage or the membrane potential of the neuron) is sampled and compared with the external standard signal of the electric electrode. The error between the sampled variable and the external standard signal of the electrode is input into the system only when the sampled variable surpasses the selected thresholds. The numerical simulation results confirm that the chaotic H-R system can be controlled to reach arbitrary n-periodical (n = 1, 2, 3, 4, 5, 6,...) orbit or stable state even when just one variable is feed backed into the system intermittently. The chaotic Chua circuit is also investigated to check its model independence and effectiveness of the schemes and the equivalence of the two schemes are confirmed again.

  18. OBTAINING STRIPS WITH VARIABLE THICKNESS AND CONTROLLED WIDENING

    Directory of Open Access Journals (Sweden)

    L. A. Isayevich

    2008-01-01

    Full Text Available The paper describes flow chart of strip rolling with variable thickness in the rolls with changeable clearance between them and non-driven rollers that ensure spread widening control. The paper presents necessary formulae for calculation of backward tension in the rolls which is considered as drawing tension in the rollers. Accomplishment of the given process is theoretically substantiated in the paper.

  19. Trajectory controllability of semilinear systems with multiple variable delays in control

    Energy Technology Data Exchange (ETDEWEB)

    Klamka, Jerzy, E-mail: Jerzy.Klamka@polsl.pl, E-mail: Michal.Niezabitowski@polsl.pl; Niezabitowski, Michał, E-mail: Jerzy.Klamka@polsl.pl, E-mail: Michal.Niezabitowski@polsl.pl [Silesian University of Technology, Faculty of Automatic Control, Electronics and Computer Science, Institute of Automatic Control, 16 Akademicka Street, 44-101 Gliwice (Poland)

    2014-12-10

    In this paper, finite-dimensional dynamical control system described by semilinear differential state equation with multiple variable delays in control are considered. The concept of controllability we extend on trajectory controllability for systems with multiple point delays in control. Moreover, remarks and comments on the relationships between different concepts of controllability are presented. Finally, simple numerical example, which illustrates theoretical considerations is also given. The possible extensions are also proposed.

  20. LABORATORY INVESTIGATION OF VARIABLE SPEED CONTROL OF SYNCHRONOUS GENERATOR WITH A BOOST CONVERTER FOR WIND TURBINE APPLICATIONS

    DEFF Research Database (Denmark)

    Sharma, Ranjan; Rasmussen, Tonny Wederberg

    2008-01-01

    This paper includes the experimental and simulated results of variable speed control of a synchronous generator. To achieve controlled variable speed operation, the synchronous generator is loaded with a three phase rectifier and a boost converter. The terminal voltage of the generator can...... showed some promising results and the overall system response is found positive. Also a Matlab simulation is performed for single turbine system including grid side inverter. The results are presented here in brief....

  1. Two-phase dusty fluid flow along a cone with variable properties

    Science.gov (United States)

    Siddiqa, Sadia; Begum, Naheed; Hossain, Md. Anwar; Mustafa, Naeem; Gorla, Rama Subba Reddy

    2016-09-01

    In this paper numerical solutions of a two-phase natural convection dusty fluid flow are presented. The two-phase particulate suspension is investigated along a vertical cone by keeping variable viscosity and thermal conductivity of the carrier phase. Comprehensive flow formations of the gas and particle phases are given with the aim to predict the behavior of heat transport across the heated cone. The influence of (1) air with particles, (2) water with particles and (3) oil with particles are shown on shear stress coefficient and heat transfer coefficient. It is recorded that sufficient increment in heat transport rate can be achieved by loading the dust particles in the air. Further, distribution of velocity and temperature of both the carrier phase and the particle phase are shown graphically for the pure fluid (air, water) as well as for the fluid with particles (air-metal and water-metal particle mixture).

  2. LQR Controller for Toroidal Continuously Variable Transmission in Reverse Motion

    Science.gov (United States)

    Mensler, Michel; Kawabe, Taketoshi; Joe, Shinichiro

    The system considered in this paper is a Toroidal Continuously Variable Transmission (TCVT) system for cars. This system is unstable in reverse motion as some mechanical parts have been removed from the original one for cost reduction, and the gear ratio has to be regulated around its nominal value for car reverse motion. The control theory used here is the Linear Quadratic Regulator (LQR) associated to a gain-scheduling technique, as the TCVT system is nonlinear according to the car speed. Moreover, as the LQR method requires the entire TCVT state vector and as the only available signal is the gear ratio, a full-order observer is designed. In order to take the other nonlinearities of the system into account, the observer is nonlinear: a diffeomorphism is then used for converting the variables provided by the nonlinear observer into the needed variables. In order to verify the effectiveness and the robustness of the controller against the car speed and the torque shift disturbance phenomenon, several experiments with a test-bed and with an actual vehicle have been performed and showed the efficiency of the proposed controller.

  3. Maximum Output Power Control System of Variable-Speed Small Wind Generators

    Science.gov (United States)

    Amano, Yoko; Kajiwara, Hiroyuki

    This paper proposes a maximum output power control system of variable-speed small wind generators. Paying attention to an optimum rotational speed of a single phase AC wind generator which can obtain maximum output power according to natural wind speed, the proposed method adjusts the rotational speed of the single phase AC generator to the optimum rotational speed. Since this adjustment is realized on line so that it can be adapted for variable-speed wind, a generated power brake links directly with the single phase AC generator, and the rotational speed of the single phase AC generator is adjusted by controlling the current that flows the FET (Field-Effect Transistor) device as the generated power brake. In order to reduce heat loss of the FET device, the PWM (Pulse Width Modulation) controller is introduced. Moreover, the experimental system of the proposed method is constituted and the experiment is performed. Finally, the validity and the practicality of the proposed method are confirmed by experimental results.

  4. Digitally controlled oscillator design with a variable capacitance XOR gate

    Institute of Scientific and Technical Information of China (English)

    Manoj Kumar; Sandeep K. Arya; Sujata Pandey

    2011-01-01

    A digitally controlled oscillator (DCO) using a three-transistor XOR gate as the variable load has been presented.A delay cell using an inverter and a three-transistor XOR gate as the variable capacitance is also proposed.Three-,five- and seven-stage DCO circuits have been designed using the proposed delay cell.The output frequency is controlled digitally with bits applied to the delay cells.The three-bit DCO shows output frequency and power consumption variation in the range of 3.2486-4.0267 GHz and 0.6121-0.3901 mW,respectively,with a change in the control word 1 1 1-000.The five-bit DCO achieves frequency and power of 1.8553-2.3506 GHz and 1.0202-0.6501 mW,respectively,with a change in the control word 11111-00000.Moreover,the seven-bit DCO shows a frequency and power consumption variation of 1.3239-1.6817 GHz and 1.4282-0.9102 m W,respectively,with a varying control word 1111111-0000000.The power consumption and output frequency of the proposed circuits have been compared with earlier reported circuits and the present approaches show significant improvements.

  5. Continuous relative phase variability during an exhaustive run in runners with a history of iliotibial band syndrome.

    Science.gov (United States)

    Miller, Ross H; Meardon, Stacey A; Derrick, Timothy R; Gillette, Jason C

    2008-08-01

    Previous research has proposed that a lack of variability in lower extremity coupling during running is associated with pathology. The purpose of the study was to evaluate lower extremity coupling variability in runners with and without a history of iliotibial band syndrome (ITBS) during an exhaustive run. Sixteen runners ran to voluntary exhaustion on a motorized treadmill while a motion capture system recorded reflective marker locations. Eight runners had a history of ITBS. At the start and end of the run, continuous relative phase (CRP) angles and CRP variability between strides were calculated for key lower extremity kinematic couplings. The ITBS runners demonstrated less CRP variability than controls in several couplings between segments that have been associated with knee pain and ITBS symptoms, including tibia rotation-rearfoot motion and rearfoot motion-thigh ad/abduction, but more variability in knee flexion/extension-foot ad/abduction. The ITBS runners also demonstrated low variability at heel strike in coupling between rearfoot motion-tibia rotation. The results suggest that runners prone to ITBS use abnormal segmental coordination patterns, particular in couplings involving thigh ad/abduction and tibia internal/external rotation. Implications for variability in injury etiology are suggested.

  6. Effect of design variables on starting torque of single phase flux-reversal machine

    Science.gov (United States)

    Won, Sung Hong; Kim, Tae Heoung; Jang, Ki-Bong; Choi, Seung-Kil; Oh, Won Seok; Lee, Ju

    2006-04-01

    This article introduces a single phase flux-reversal machine (FRM) and presents the design method to improve its starting torque. The effects of the design parameters on the characteristic and starting torque are analyzed by the finite element method. The design variables considered are tapered airgap, stepped airgap, slotted teeth, and asymmetric PM width. As a result, we can find the best model in producing starting torque of a single phase 2/3 FRM.

  7. Experimental demonstration of continuous variable cloning with phase-conjugate inputs

    DEFF Research Database (Denmark)

    Sabuncu, Metin; Andersen, Ulrik Lund; Leuchs, G.

    2007-01-01

    We report the first experimental demonstration of continuous variable cloning of phase-conjugate coherent states as proposed by Cerf and Iblisdir [Phys. Rev. Lett. 87, 247903 (2001)]. In contrast to this proposal, the cloning transformation is accomplished using only linear optical components......, homodyne detection, and feedforward. As a result of combining phase conjugation with a joint measurement strategy, superior cloning is demonstrated with cloning fidelities reaching 89%....

  8. Dual mode adaptive fractional order PI controller with feedforward controller based on variable parameter model for quadruple tank process.

    Science.gov (United States)

    Roy, Prasanta; Roy, Binoy Krishna

    2016-07-01

    The Quadruple Tank Process (QTP) is a well-known benchmark of a nonlinear coupled complex MIMO process having both minimum and nonminimum phase characteristics. This paper presents a novel self tuning type Dual Mode Adaptive Fractional Order PI controller along with an Adaptive Feedforward controller for the QTP. The controllers are designed based on a novel Variable Parameter Transfer Function model. The effectiveness of the proposed model and controllers is tested through numerical simulation and experimentation. Results reveal that the proposed controllers work successfully to track the reference signals in all ranges of output. A brief comparison with some of the earlier reported similar works is presented to show that the proposed control scheme has some advantages and better performances than several other similar works.

  9. Vector Controlled Two Phase Induction Motor and To A Three Phase Induction Motor

    Directory of Open Access Journals (Sweden)

    K.krishna Rao (PG student

    2014-12-01

    Full Text Available This paper presents vector controlled of single phase induction motor. some problems are with vector controlled SPIM.As SPIM’s are typically to maintain speed and also about the complex implementation of vector controlled SPIM.the implemantion of the proposed vector controlled TPIM compared to the vector controlled SPIM. The general modal sutable for vector control of the unsymmentrical two phase induction motor and also stator flux oriented controlled strategies are analized. the comparative performance of both has been presented in this work with help of a practical three phase motor.

  10. Identification of manipulated variables for a glycosylation control strategy.

    Science.gov (United States)

    St Amand, Melissa M; Radhakrishnan, Devesh; Robinson, Anne S; Ogunnaike, Babatunde A

    2014-10-01

    N-linked glycan distribution affects important end-use characteristics such as the bioactivity and efficacy of many therapeutic proteins, (including monoclonal antibodies), in vivo. Yet, obtaining desired glycan distributions consistently during batch-to-batch production can be challenging for biopharmaceutical manufacturers. While an appropriately implemented on-line glycosylation control strategy during production can help to ensure a consistent glycan distribution, to date no such strategies have been reported. Our goal is to develop and validate a comprehensive strategy for effective on-line control of glycosylation, the successful achievement of which requires first identifying appropriate manipulated variables that can be used to direct the glycan distribution to a desired state. While various culture conditions such as bioreactor process variables, media type, and media supplements have been shown to affect the glycan distribution, in this study we focus on the latter. Specifically, we implemented a statistically designed series of experiments to determine the significant main effects (as well as interaction effects) of media supplementation with manganese, galactose, ammonia and found that each had significant effects on certain glycans. We also include data indicating the glycosylation enzyme gene transcript levels as well as the intracellular nucleotide sugar concentrations in the presence of the media supplements to provide insight into the intracellular conditions that may be contributing to the changes in glycan distribution. The acquired experimental data sets were then used to identify which glycans can be controlled by the media supplements and to what degree. We determined that MnCl2 can be used as a manipulated variable to increase the relative abundance of M51 and decrease FA2 simultaneously, and galactose can be used as a manipulated variable to increase the relative abundance of FA2G1 and decrease FA2 and A2 simultaneously. © 2014 Wiley

  11. Variable stoichiometry with thermodynamic control in ADM1.

    Science.gov (United States)

    Rodríguez, J; Lema, J M; van Loosdrecht, M C M; Kleerebezem, R

    2006-01-01

    The effect of a variable stoichiometry of the carbohydrate fermentation process in the IWA Anaerobic Digestion Model No.1 (ADM1) is investigated. Most existing anaerobic digestion models including ADM1 consider a fixed-stoichiometry for their conversion processes. The ADM1 model was first transformed into an only mol based model to remove some errors derived from the mixed COD-mol based standard model and to allow for implementation of the variable stoichiometry. Consequently, the values of the butyrate and acetate catabolic yields of carbohydrate fermentation are made dependent on the hydrogen concentration and the reactor pH according to the predictions of a recently developed mixed culture fermentation model based on thermodynamic considerations. The simulation results obtained showed no significantly different responses in terms of effluent quality and system robustness between the standard and the variable stoichiometry ADM1 under overload conditions, and for both single- and two-step anaerobic digestion configurations. This behaviour is explained by the non-limiting acetogenic activity that compensated for the changes in the acidogenic products, typical behaviour for serial processes close to equilibrium. Based on the results obtained, thermodynamic rather than kinetic control for these conversions is suggested. Depending on the objectives to be met, lumping of carbohydrate fermenters and oxidative acetogens into a single biomass group with a variable stoichiometry is proposed for further consideration.

  12. Variable Voltage Source Inverter with controlled frequency spectrum based on Random Pulse Width Modulation

    Directory of Open Access Journals (Sweden)

    Muhammad Farrukh Yaqub

    2012-01-01

    Full Text Available This paper presents a new method for single phase variable voltage inverter based on Random Pulse Width Modulation. In Random Pulse Width Modulation based inverter, the frequency spectrum of the output current and voltage waveforms becomes continuous because of the randomization of the switching function of the devices controlling the output voltages. This paper establishes a theory that if the distributions of the random numbers generated by the random source are kept within certain limit with respect to the peak value of reference sinusoidal waveform, the frequency spectrum can be controlled. On the basis of the results, a novel drive using variable tap changing transformer (optional and adaptive random number generator, to control the ratio between the numbers generated by the random source and the reference waveform has been suggested that will guarantee a better power quality profile for a broad range of output voltages.

  13. Sensorless speed control of a five-phase induction machine under open-phase condition

    Directory of Open Access Journals (Sweden)

    Ahmed S. Morsy

    2014-05-01

    Full Text Available Recently, multiphase machines have been promoted as competitors to their three-phase counterparts in high-power safety-critical drive applications. Among numerous advantages of multiphase induction machine (IM drives, self-starting and operation under open phase(s stand as the most salient features. With open phase(s, optimal current control provides disturbance- free operation given a set of objective functions. Although hysteresis current control was merely employed in the literature as it offers a simple controller structure to control the remaining healthy phases, it is not suitable for high-power applications. In the literature, multiple synchronous reference frame (dq control can be an alternative; however, it requires back and forth transformations with several calculations and additional sophistication. In this paper, a simple technique employing adaptive proportional resonant (PR current controllers is presented to control a five-phase IM under open-phase conditions. Results for both volt/hertz (V/f and field oriented control (FOC systems are presented. Moreover, sensorless operation under fault condition is also demonstrated by estimating the machine speed using a rotor flux-based model reference adaptive system (MRAS speed estimator. The proposed controllers are experimentally verified and compared. Although FOC provides better dynamic performance, V/f control offers a simpler control structure and a lower number of PR controllers.

  14. Complexity Variability Assessment of Nonlinear Time-Varying Cardiovascular Control

    Science.gov (United States)

    Valenza, Gaetano; Citi, Luca; Garcia, Ronald G.; Taylor, Jessica Noggle; Toschi, Nicola; Barbieri, Riccardo

    2017-01-01

    The application of complex systems theory to physiology and medicine has provided meaningful information about the nonlinear aspects underlying the dynamics of a wide range of biological processes and their disease-related aberrations. However, no studies have investigated whether meaningful information can be extracted by quantifying second-order moments of time-varying cardiovascular complexity. To this extent, we introduce a novel mathematical framework termed complexity variability, in which the variance of instantaneous Lyapunov spectra estimated over time serves as a reference quantifier. We apply the proposed methodology to four exemplary studies involving disorders which stem from cardiology, neurology and psychiatry: Congestive Heart Failure (CHF), Major Depression Disorder (MDD), Parkinson’s Disease (PD), and Post-Traumatic Stress Disorder (PTSD) patients with insomnia under a yoga training regime. We show that complexity assessments derived from simple time-averaging are not able to discern pathology-related changes in autonomic control, and we demonstrate that between-group differences in measures of complexity variability are consistent across pathologies. Pathological states such as CHF, MDD, and PD are associated with an increased complexity variability when compared to healthy controls, whereas wellbeing derived from yoga in PTSD is associated with lower time-variance of complexity. PMID:28218249

  15. Complexity Variability Assessment of Nonlinear Time-Varying Cardiovascular Control

    Science.gov (United States)

    Valenza, Gaetano; Citi, Luca; Garcia, Ronald G.; Taylor, Jessica Noggle; Toschi, Nicola; Barbieri, Riccardo

    2017-02-01

    The application of complex systems theory to physiology and medicine has provided meaningful information about the nonlinear aspects underlying the dynamics of a wide range of biological processes and their disease-related aberrations. However, no studies have investigated whether meaningful information can be extracted by quantifying second-order moments of time-varying cardiovascular complexity. To this extent, we introduce a novel mathematical framework termed complexity variability, in which the variance of instantaneous Lyapunov spectra estimated over time serves as a reference quantifier. We apply the proposed methodology to four exemplary studies involving disorders which stem from cardiology, neurology and psychiatry: Congestive Heart Failure (CHF), Major Depression Disorder (MDD), Parkinson’s Disease (PD), and Post-Traumatic Stress Disorder (PTSD) patients with insomnia under a yoga training regime. We show that complexity assessments derived from simple time-averaging are not able to discern pathology-related changes in autonomic control, and we demonstrate that between-group differences in measures of complexity variability are consistent across pathologies. Pathological states such as CHF, MDD, and PD are associated with an increased complexity variability when compared to healthy controls, whereas wellbeing derived from yoga in PTSD is associated with lower time-variance of complexity.

  16. Investigation of torque control using a variable slip induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Bossanyi, E.A.; Gamble, C.R.

    1991-07-01

    An investigation of the possibilities of using a variable slip induction generator to control wind turbine transmission torque has been carried out. Such a generator consists of a wound rotor induction generator with its rotor winding connected to an external variable resistance circuit. By controlling the external resistance, the torque-slip characteristic of the generator can be modified, allowing efficient, low-slip operation below rated wind speed and compliant, high-slip operation above rated, where the additional losses are of no consequence but the resulting compliance allows a much reduced duty to be specified for the transmission and gearbox. A number of hardware options have been investigated for the variable resistance rotor circuit, the main options being either a rectifier and DC chopper or an AC regulator. Both of these options use semiconductor switching devices, for which the relative merits of thyristors, MOSFETs, GTOs and transistors have been investigated. A favoured scheme consisting of an AC regulator using GTOs has been provisionally selected. This choice uses some non-standard equipment but is expected to give negligible problems with harmonics. A comprehensive simulation model has been set up and used to investigate the behaviour of the whole system. (author).

  17. Speed Control of Induction Motor by Using Variable Frequency

    Directory of Open Access Journals (Sweden)

    Drive Pooja Shinde

    2014-04-01

    Full Text Available The variable speed drive is focused on voltage amplitude control. However, its only control speed in constraint limits. The load on Induction Motor is not constant & vary as per load requirement. so speed must be change as per load. If the supply voltage decreased motor torque also decreases, for maintaining same torque, slip decreases hence speed falls and motor speed is directly proportional to supply frequency, hence to maintain a speed, the supply V/F ratio must be vary accordingly. But the speed is not vary proportion to application so it consume the rated power and it becomes economically disadvantages. To overcome above problem a new concept of Variable Frequency Drive (VFD is introduced. Adding a Variable Frequency Drive (VFD to a motor driven system can offer potential energy saving in a system in which the load vary with time. The primary function of VFD in application is to provide energy saving, speed reduction of 20% can save energy upto 50%.

  18. Variable universe adaptive fuzzy control on the quadruple inverted pendulum

    Institute of Scientific and Technical Information of China (English)

    LI; Hongxing(

    2002-01-01

    [1]Magana,M.E.,Fuzzy-logic control of an inverted pendulum with vision feedback,IEEE Transactions on Education,1998,41(2):165.[2]Chen,C.S.,Chen,W.L.,Robust adaptive sliding-mode control using fuzzy modeling for an inverted-pendulum system,IEEE Transactions on Industrial Electronics,1998,45(2):297.[3]Cheng,F.Y.,Zhong,G.M.,Li,Y.S.et al.,Fuzzy control of a double-inverted pendulum,Fuzzy Sets and System,1996,79(3):315-321.[4]Zhang,H.M.,Ma,X.W.,Xu,W.et al.,Design fuzzy controllers complex systems with an application to 3-stage inverted pendulums,Information Sciences,1993,72:271.[5]Zhang,M.L.,Hao,J.K.,Hei,W.D.,Personification intelligence control and triple inverted pendulum,Journal of Aeronautics (in Chinese),1995,16(4):654.[6]Li,H.X.,To see the success of fuzzy logic from mathematical essence of fuzzy control,Fuzzy Systems and Mathematics (in Chinese),1995,9(4):1-14.[7]Li,H.X.,Mathematical essence of fuzzy controls and design of a kind of high precision fuzzy controllers,Control Theory and Application (in Chinese),1997,14(6):868.[8]Li,H.X.,Adaptive fuzzy controllers based on variable universe,Science in China,Ser.E,1999,42(1):10.[9]Li,H.X.,Interpolation mechanism of fuzzy control,Science in China,Ser.E,1998,41(3):312.[10]Li,H.X.,The equivalence between fuzzy logic systems and feedforward neural networks,Science in China,Ser.E,2000,43(1):42.

  19. Power Control in Wireless Sensor Networks with Variable Interference

    Directory of Open Access Journals (Sweden)

    Michele Chincoli

    2016-01-01

    Full Text Available Adaptive transmission power control schemes have been introduced in wireless sensor networks to adjust energy consumption under different network conditions. This is a crucial goal, given the constraints under which sensor communications operate. Power reduction may however have counterproductive effects to network performance. Yet, indiscriminate power boosting may detrimentally affect interference. We are interested in understanding the conditions under which coordinated power reduction may lead to better spectrum efficiency and interference mitigation and, thus, have beneficial effects on network performance. Through simulations, we analyze the performance of sensor nodes in an environment with variable interference. Then we study the relation between transmission power and communication efficiency, particularly in the context of Adaptive and Robust Topology (ART control, showing how appropriate power reduction can benefit both energy and spectrum efficiency. We also identify critical limitations in ART, discussing the potential of more cooperative power control approaches.

  20. A Unified Symmetry of Mechanical Systems with Variable Mass in Phase Space

    Institute of Scientific and Technical Information of China (English)

    WANG Peng; FANG Jian-Hui; ZHANG Peng-Yu; DING Ning

    2006-01-01

    In this paper, the definition and the criterion of a unified symmetry of the mechanical system with variable mass in phase space are given. The Noether conserved quantity, the generalized Hojman conserved quantity, and Mei conserved quantity deduced from the unified symmetry are obtained. An example is given to illustrate the application of the results.

  1. A phase-variable surface layer from the gut symbiont bacteroides thetaiotaomicron

    OpenAIRE

    Fischbach, Michael; Taketani, M; Donia, MS; Jacobson, AN; Lambris, JD; Fischbach, MA

    2015-01-01

    © 2015 Taketani et al.The capsule from Bacteroides, a common gut symbiont, has long been a model system for studying the molecular mechanisms of host-symbiont interactions. The Bacteroides capsule is thought to consist of an array of phase-variable polysac

  2. Phase-noise limitations in continuous-variable quantum key distribution with homodyne detection

    Science.gov (United States)

    Corvaja, Roberto

    2017-02-01

    In continuous-variables quantum key distribution with coherent states, the advantage of performing the detection by using standard telecoms components is counterbalanced by the lack of a stable phase reference in homodyne detection due to the complexity of optical phase-locking circuits and to the unavoidable phase noise of lasers, which introduces a degradation on the achievable secure key rate. Pilot-assisted phase-noise estimation and postdetection compensation techniques are used to implement a protocol with coherent states where a local laser is employed and it is not locked to the received signal, but a postdetection phase correction is applied. Here the reduction of the secure key rate determined by the laser phase noise, for both individual and collective attacks, is analytically evaluated and a scheme of pilot-assisted phase estimation proposed, outlining the tradeoff in the system design between phase noise and spectral efficiency. The optimal modulation variance as a function of the phase-noise amount is derived.

  3. Note on the phase space of asymptotically flat gravity in Ashtekar-Barbero variables

    CERN Document Server

    Campiglia, Miguel

    2014-01-01

    We describe the canonical phase space of asymptotically flat gravity in Ashtekar-Barbero variables. We show that the Gauss constraint multiplier must fall off slower than previously considered in order to recover ADM phase space. The generators of the asymptotic Poincare group are derived within the Ashtekar-Barbero phase space without reference to the ADM generators. The resulting expressions are shown to agree, modulo Gauss constraint terms, with those obtained from the ADM generators. A payoff of this procedure is a new expression for the generator of asymptotic rotations which is polynomial in the triad and hence better suited for quantum theory. Our treatment complements earlier description by Thiemann in the context of self-dual variables.

  4. Note on the phase space of asymptotically flat gravity in Ashtekar-Barbero variables

    Science.gov (United States)

    Campiglia, Miguel

    2015-07-01

    We describe the canonical phase space of asymptotically flat gravity in Ashtekar-Barbero (AB) variables. We show that the Gauss constraint multiplier must fall off slower than previously considered in order to recover ADM phase space. The generators of the asymptotic Poincare group are derived within the AB phase space without reference to the ADM generators. The resulting expressions are shown to agree, modulo Gauss constraint terms, with those obtained from the ADM generators. A payoff of this procedure is a new expression for the generator of asymptotic rotations, which is polynomial in the triad and hence better suited for quantum theory. Our treatment complements an earlier description by Thiemann in the context of self-dual variables.

  5. Carta de control r con intervalos de muestreo variables

    OpenAIRE

    Moreno Cortés, Ana Lucia; Vargas Navas, José Alberto

    2012-01-01

    La carta de control R usada para monitorear la variabilidad de un proceso, se basa en los rangos calculados a partir de muestras seleccionadas en tiempos igualmente espaciados. En este artículo se modifica la carta R usual, permitiendo que los intervalos entre las muestras puedan ser variables. La idea es que el intervalo de tiempo entre las muestras i e i + 1 sea corto, si el rango de la i-ésima muestra da indicación de un posible cambio en la variabilidad del proceso, y largo en caso contra...

  6. Optimal Control of Thermo--Fluid Phenomena in Variable Domains

    Science.gov (United States)

    Volkov, Oleg; Protas, Bartosz

    2008-11-01

    This presentation concerns our continued research on adjoint--based optimization of viscous incompressible flows (the Navier--Stokes problem) coupled with heat conduction involving change of phase (the Stefan problem), and occurring in domains with variable boundaries. This problem is motivated by optimization of advanced welding techniques used in automotive manufacturing, where the goal is to determine an optimal heat input, so as to obtain a desired shape of the weld pool surface upon solidification. We argue that computation of sensitivities (gradients) in such free--boundary problems requires the use of the shape--differential calculus as a key ingredient. We also show that, with such tools available, the computational solution of the direct and inverse (optimization) problems can in fact be achieved in a similar manner and in a comparable computational time. Our presentation will address certain mathematical and computational aspects of the method. As an illustration we will consider the two--phase Stefan problem with contact point singularities where our approach allows us to obtain a thermodynamically consistent solution.

  7. The Dynamics of Coupled Oscillator Phase Control

    Science.gov (United States)

    Pogorzelski, R. J.; Maccarini, P. F.; York, R. A.

    1998-01-01

    Arrays of coupled oscillators have been proposed as means of realizing high power rf sources via coherent spatial power combining. In such applications, a uniform phase distribution over the aperture is usually desired. However, it has been shown that by detuning some of the oscillators away from the oscillation frequency of the ensemble of oscillators, one may achieve other useful aperture phase distributions. Of particular interest among those achievable are linear phase distributions because these result in steering of the output rf beam away from the broadside direction. The theory describing the behavior of such arrays of coupled oscillators is quite complicated since the phenomena involved are inherently nonlinear. However, a simplified theory has been developed which facilitates intuitive understanding. This simplified theory is based on a "continuum model" in which the aperture phase is represented by a continuous function of the aperture coordinates. A challenging aspect of the development of this theory is the derivation of appropriate boundary conditions at the edges or ends of the array.

  8. Anomalous Surface Wave Launching by Handedness Phase Control

    KAUST Repository

    Zhang, Xueqian

    2015-10-09

    Anomalous launch of a surface wave with different handedness phase control is achieved in a terahertz metasurface based on phase discontinuities. The polarity of the phase profile of the surface waves is found to be strongly correlated to the polarization handedness, promising polarization-controllable wavefront shaping, polarization sensing, and environmental refractive-index sensing. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Semiactive variable stiffness control for parametric vibration of cables

    Institute of Scientific and Technical Information of China (English)

    Li Hui; Chen Wenli; Ou Jinping

    2006-01-01

    In this paper, a semiactive variable stiffness (SVS) device is used to decrease cable oscillations caused by parametric excitation, and the equation of motion of the parametric vibration of the cable with this SVS device is presented.The ON/OFF control algorithm is used to operate the SVS control device. The vibration response of the cable with the SVS device is numerically studied for a variety of additional stiffness combinations in both the frequency and time domains and for both parametric and classical resonance vibration conditions. The numerical studies further consider the cable sag effect.From the numerical results, it is shown that the SVS device effectively suppresses the cable resonance vibration response, and as the stiffness of the device increases, the device achieves greater suppression of vibration. Moreover, it was shown that the SVS device increases the critical axial displacement of the excitation under cable parametric vibration conditions.

  10. PROCESS VARIABILITY REDUCTION THROUGH STATISTICAL PROCESS CONTROL FOR QUALITY IMPROVEMENT

    Directory of Open Access Journals (Sweden)

    B.P. Mahesh

    2010-09-01

    Full Text Available Quality has become one of the most important customer decision factors in the selection among the competing product and services. Consequently, understanding and improving quality is a key factor leading to business success, growth and an enhanced competitive position. Hence quality improvement program should be an integral part of the overall business strategy. According to TQM, the effective way to improve the Quality of the product or service is to improve the process used to build the product. Hence, TQM focuses on process, rather than results as the results are driven by the processes. Many techniques are available for quality improvement. Statistical Process Control (SPC is one such TQM technique which is widely accepted for analyzing quality problems and improving the performance of the production process. This article illustrates the step by step procedure adopted at a soap manufacturing company to improve the Quality by reducing process variability using Statistical Process Control.

  11. Microcontroller based PWM Inverter for Speed Control of a Three Phase Induction Motor

    Directory of Open Access Journals (Sweden)

    M. A. Latif

    2013-04-01

    Full Text Available Three phase induction motor has proven to be an extremely reliable electromechanical energy conversion device for over 100 years. The speed control of induction motor is a crying need for the real world industrial applications. However, there are so many options available for the precise speed control of induction motor except by changingthe frequency. Therefore to achieve the goal of speed control of induction motor, there is no alternative of inverters. With the availability of high speed power semiconductor devices, the three phase inverters play the key role for variable speed ac motor drives. In addition to the speed control, the inverter can also provide some unique features, like voltage control, torque control, power factor correction, auto breaking, built in protection system and so forth.In this paper, a three phases PWM inverter using MC3PHAC microcontroller with computer interface is proposed to run a squirrel case induction motor. Some results of the proposed inverter are presented.

  12. Modeling and control of three phase rectifier with electronic smoothing inductor

    DEFF Research Database (Denmark)

    Singh, Yash Veer; Rasmussen, Peter Omand; Andersen, Torben Ole

    2011-01-01

    controlled variable impedance. This increases power factor (PF) and reduces total harmonic distortions (THDs) in mains current. The ESI based rectifier enables compact and cost effective design of three phase electric drive as size of passive components is reduced significantly. In order to carry out...

  13. Analysis of Three-Phase Thyristor Phase Control Circuit with Series RLC Elements

    OpenAIRE

    Himei, Toyoji; Nakanishi, Sen-ichiro; Funabiki, Shigeyuki; Komatsubara, Hitoshi; Kurose, Osamu

    1983-01-01

    An ac phase control circuit by thyristor is widely used in industry, The characteristics of the singlephase circuit with series RLC elements are numerically analyzed, and is reported the interesting phenomenon of step-up voltage without transformer. However, the performance of three phase phase control circuit with series RLC elements is not made clear. In this paper, the performance of three-phasecontrol circuit of a balanced and an unbalanced load with series RLC elements is described. The ...

  14. A computational model for aperture control in reach-to-grasp movement based on predictive variability

    Directory of Open Access Journals (Sweden)

    Naohiro eTakemura

    2015-12-01

    Full Text Available In human reach-to-grasp movement, visual occlusion of a target object leads to a larger peak grip aperture compared to conditions where online vision is available. However, no previous computational and neural network models for reach-to-grasp movement explain the mechanism of this effect. We simulated the effect of online vision on the reach-to-grasp movement by proposing a computational control model based on the hypothesis that the grip aperture is controlled to compensate for both motor variability and sensory uncertainty. In this model, the aperture is formed to achieve a target aperture size that is sufficiently large to accommodate the actual target; it also includes a margin to ensure proper grasping despite sensory and motor variability. To this end, the model considers: i the variability of the grip aperture, which is predicted by the Kalman filter, and ii the uncertainty of the object size, which is affected by visual noise. Using this model, we simulated experiments in which the effect of the duration of visual occlusion was investigated. The simulation replicated the experimental result wherein the peak grip aperture increased when the target object was occluded, especially in the early phase of the movement. Both predicted motor variability and sensory uncertainty play important roles in the online visuomotor process responsible for grip aperture control.

  15. Semi-analytic variable charge solitary waves involving dust phase-space vortices (holes)

    Energy Technology Data Exchange (ETDEWEB)

    Tribeche, Mouloud; Younsi, Smain; Amour, Rabia; Aoutou, Kamel [Plasma Physics Group, Faculty of Sciences-Physics, Theoretical Physics Laboratory, University of Bab-Ezzouar, USTHB BP 32, El Alia, Algiers 16111 (Algeria)], E-mail: mtribeche@usthb.dz

    2009-09-15

    A semi-analytic model for highly nonlinear solitary waves involving dust phase-space vortices (holes) is outlined. The variable dust charge is expressed in terms of the Lambert function and we take advantage of this transcendental function to investigate the localized structures that may occur in a dusty plasma with variable charge trapped dust particles. Our results which complement the previously published work on this problem (Schamel et al 2001 Phys. Plasmas 8 671) should be of basic interest for experiments that involve the trapping of dust particles in ultra-low-frequency dust acoustic modes.

  16. Simulation and Analyis of a Continuous Variable Cam Phasing Internal Combustion Engine

    OpenAIRE

    Hammarlund, Pär

    2008-01-01

    The development of fuel efficient internal combustion engines (ICE)have resulted in a variety of different solutions. One of those are the variable valve timing and an implemenation of such is the Continuous Variable Cam Phasing (CVCP). This thesis have used a simulation package, psPack, for the simulation of the gas exchange process for an ICE with CVCP. The purpose of the simulations was to investigate what kind of design parameters, e.g. the length of an intake pipe or the duration of comb...

  17. Dynamics and Predictive Control of Gas Phase Propylene Polymerization in Fluidized Bed Reactors

    Institute of Scientific and Technical Information of China (English)

    Ahmad Shamiri; Mohamed azlan Hussain; Farouq sabri Mjalli; Navid Mostoufi; Seyedahmad Hajimolana

    2013-01-01

    A two-phase dynamic model, describing gas phase propylene polymerization in a fluidized bed reactor, was used to explore the dynamic behavior and process control of the polypropylene production rate and reactor temperature. The open loop analysis revealed the nonlinear behavior of the polypropylene fluidized bed reactor, jus-tifying the use of an advanced control algorithm for efficient control of the process variables. In this case, a central-ized model predictive control (MPC) technique was implemented to control the polypropylene production rate and reactor temperature by manipulating the catalyst feed rate and cooling water flow rate respectively. The corre-sponding MPC controller was able to track changes in the setpoint smoothly for the reactor temperature and pro-duction rate while the setpoint tracking of the conventional proportional-integral (PI) controller was oscillatory with overshoots and obvious interaction between the reactor temperature and production rate loops. The MPC was able to produce controller moves which not only were well within the specified input constraints for both control vari-ables, but also non-aggressive and sufficiently smooth for practical implementations. Furthermore, the closed loop dynamic simulations indicated that the speed of rejecting the process disturbances for the MPC controller were also acceptable for both controlled variables.

  18. Stimulus presentation at specific neuronal oscillatory phases experimentally controlled with tACS: implementation and applications

    Directory of Open Access Journals (Sweden)

    Sanne Ten Oever

    2016-10-01

    Full Text Available In recent years it has become increasingly clear that both the power and phase of oscillatory brain activity can influence the processing and perception of sensory stimuli. Transcranial alternating current stimulation (tACS can phase-align and amplify endogenous brain oscillations and has often been used to control and thereby study oscillatory power. Causal investigation of oscillatory phase is more difficult, as it requires precise real-time temporal control over both oscillatory phase and sensory stimulation. Here, we present hardware and software solutions allowing temporally precise presentation of sensory stimuli during tACS at desired tACS phases, enabling causal investigations of oscillatory phase. We developed freely available and easy to use software, which can be coupled with standard commercially available hardware to allow flexible and multi-modal stimulus presentation (visual, auditory, magnetic stimuli, etc. at pre-determined tACS-phases, opening up a range of new research opportunities. We validate that stimulus presentation at tACS phase in our setup is accurate to the sub-millisecond level with high inter-trial consistency. Conventional methods investigating the role of oscillatory phase such as magneto-/electroencephalography can only provide correlational evidence. Using brain stimulation with the described methodology enables investigations of the causal role of oscillatory phase. This setup turns oscillatory phase into an independent variable, allowing innovative and systematic studies of its functional impact on perception and cognition.

  19. Variable-length balanced codes for quadrature phase shift keyed systems

    Directory of Open Access Journals (Sweden)

    Xin Tu

    2015-10-01

    Full Text Available The authors outline an approach to construct capacity-approaching balanced quadrature phase shift keyed (QPSK codes. These codes ensure an equal number of different symbol values and many symbol transitions in the encoded sequence in order to assist practical demodulators to accurately recover symbol values. Their codes are comprised of instantaneously decodable variable-length codewords that exhibit excellent performance with average code rates higher than previously reported fixed-length balanced QPSK codes.

  20. Phase-field modeling of fracture in variably saturated porous media

    Science.gov (United States)

    Cajuhi, T.; Sanavia, L.; De Lorenzis, L.

    2017-08-01

    We propose a mechanical and computational model to describe the coupled problem of poromechanics and cracking in variably saturated porous media. A classical poromechanical formulation is adopted and coupled with a phase-field formulation for the fracture problem. The latter has the advantage of being able to reproduce arbitrarily complex crack paths without introducing discontinuities on a fixed mesh. The obtained simulation results show good qualitative agreement with desiccation experiments on soils from the literature.

  1. Axial Phase-Darkfield-Contrast (APDC), a new technique for variable optical contrasting in light microscopy.

    Science.gov (United States)

    Piper, T; Piper, J

    2012-09-01

    Axial phase-darkfield-contrast (APDC) has been developed as an illumination technique in light microscopy which promises significant improvements and a higher variability in imaging of several transparent 'problem specimens'. With this method, a phase contrast image is optically superimposed on an axial darkfield image so that a partial image based on the principal zeroth order maximum (phase contrast) interferes with an image, which is based on the secondary maxima (axial darkfield). The background brightness and character of the resulting image can be continuously modulated from a phase contrast-dominated to a darkfield-dominated character. In order to achieve this illumination mode, normal objectives for phase contrast have to be fitted with an additional central light stopper needed for axial (central) darkfield illumination. In corresponding condenser light masks, a small perforation has to be added in the centre of the phase contrast providing light annulus. These light modulating elements are properly aligned when the central perforation is congruent with the objective's light stop and the light annulus is conjugate with the phase ring. The breadth of the condenser light annulus and thus the intensity of the phase contrast partial image can be regulated with the aperture diaphragm. Additional contrast effects can be achieved when both illuminating light components are filtered at different colours. In this technique, the axial resolution (depth of field) is significantly enhanced and the specimen's three-dimensional appearance is accentuated with improved clarity as well as fine details at the given resolution limit. Typical artefacts associated with phase contrast and darkfield illumination are reduced in our methods.

  2. Security of continuous-variable QKD: exploiting symmetries in phase space

    CERN Document Server

    Leverrier, Anthony; Grangier, Philippe; Cerf, Nicolas J

    2009-01-01

    Proving the unconditional security of a quantum key distribution (QKD) scheme is a highly challenging task as one needs to determine the most efficient attack compatible with experimental data. This task is even more demanding for continuous-variable QKD as the Hilbert space where the protocol is described is infinite dimensional. A very natural way to address this problem is to make an extensive use of the symmetries of the protocols. In this article, we investigate a symmetry in phase space that is particularly relevant to continuous-variable QKD, and explore the way towards a new quantum de Finetti theorem that would exploit this symmetry and provide a powerful tool to assess the security of continuous-variable protocols.

  3. Performance analysis of variable speed multiphase induction motor with pole phase modulation

    Directory of Open Access Journals (Sweden)

    Liu Huijuan

    2016-09-01

    Full Text Available The pole phase modulation (PPM technique is an effective method to extend speed range and torque capabilities for an integrated starter and hybrid electric vehicles applications. In this paper, the five pole-phase combination types of a multiphase induction motor (IM with 36 stator slots and 36 stator conductors are presented and compared quantitatively by using the time-stepping finite element method (TS-FEM. The 36 stator conductors of the proposed multiphase IM are fed by a 36 leg inverter and the current phase angle and amplitude of each stator conductor can be controlled independently. This paper focuses on the winding connection, the PPM technique and the performance comparative analysis of each pole-phase combination types of the proposed multiphase IM. The flux distribution, air-gap flux density, output torque, core losses and efficiency of five pole-phase combination types have been investigated.

  4. Modeling and control of three phase rectifier with electronic smoothing inductor

    DEFF Research Database (Denmark)

    Singh, Yash Veer; Rasmussen, Peter Omand; Andersen, Torben Ole

    2011-01-01

    controlled variable impedance. This increases power factor (PF) and reduces total harmonic distortions (THDs) in mains current. The ESI based rectifier enables compact and cost effective design of three phase electric drive as size of passive components is reduced significantly. In order to carry out...... stability and voltage regulation studies, the average, small-signal, dynamic model and control strategy of the ESI is developed and validated by simulation and laboratory measurements....

  5. Control of a Stand-Alone Variable Speed Wind Energy Supply System †

    Directory of Open Access Journals (Sweden)

    Mohamed M. Hamada

    2013-04-01

    Full Text Available This paper presents a simple control strategy for the operation of a variable speed stand-alone wind turbine with a permanent magnet synchronous generator (PMSG. The PMSG is connected to a three phase resistive load through a switch mode rectifier and a voltage source inverter. Control of the generator side converter is used to achieve maximum power extraction from the available wind power. Control of the DC-DC bidirectional buck-boost converter, which is connected between batteries bank and DC-link voltage, is used to maintain the DC-link voltage at a constant value. It is also used to make the batteries bank stores the surplus of wind energy and supplies this energy to the load during a wind power shortage. The load side voltage source inverter uses a relatively complex vector control scheme to control the output load voltage in terms of amplitude and frequency. The control strategy works under wind speed variation as well as with variable load. Extensive simulation results have been performed using MATLAB/SIMULINK.

  6. Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources

    Energy Technology Data Exchange (ETDEWEB)

    Hays, Lance G

    2014-07-07

    A variable phase turbine assembly will be designed and manufactured having a turbine, operable with transcritical, two-phase or vapor flow, and a generator – on the same shaft supported by process lubricated bearings. The assembly will be hermetically sealed and the generator cooled by the refrigerant. A compact plate-fin heat exchanger or tube and shell heat exchanger will be used to transfer heat from the geothermal fluid to the refrigerant. The demonstration turbine will be operated separately with two-phase flow and with vapor flow to demonstrate performance and applicability to the entire range of low temperature geothermal resources. The vapor leaving the turbine is condensed in a plate-fin refrigerant condenser. The heat exchanger, variable phase turbine assembly and condenser are all mounted on single skids to enable factory assembly and checkout and minimize installation costs. The system will be demonstrated using low temperature (237F) well flow from an existing large geothermal field. The net power generated, 1 megawatt, will be fed into the existing power system at the demonstration site. The system will demonstrate reliable generation of inexpensive power from low temperature resources. The system will be designed for mass manufacturing and factory assembly and should cost less than $1,200/kWe installed, when manufactured in large quantities. The estimated cost of power for 300F resources is predicted to be less than 5 cents/kWh. This should enable a substantial increase in power generated from low temperature geothermal resources.

  7. Quantum and Classical Effects in the Two-Frequency Kicked Rotor with Variable Initial Phase

    CERN Document Server

    Mullins, T G; Sadgrove, M P; Hoogerland, M D; Parkins, A S; Leonhardt, R

    2004-01-01

    We present an investigation into effects exhibited by the two-frequency kicked rotor. Experiments were performed and in addition quantum and classical dynamics were simulated and compared with the experimental results. The experiments involved pulsing the optical standing wave with two pulsing periods of differing frequencies and variable initial phase offset. The ratio of pulsing periods was sampled for rational and irrational values for different experimental runs. In this paper we present these results and examine the measured momentum distributions for the cause of any structures that are seen in the energy as the initial phase offset is changed. Irrational ratios exhibit no significant quantum effects, whereas rational ratios show dynamical localisation (DL) for certain values of the initial phase. However, most of the observed structure is found to be due to classical effects, in particular KAM boundaries, and is therefore not of uniquely quantum origin.

  8. Static VAR Compensator-Based Voltage Regulation for Variable-Speed Prime Mover Coupled Single-Phase Self-Excited Induction Generator

    Science.gov (United States)

    Ahmed, Tarek; Noro, Osamu; Hiraki, Eiji; Nakaoka, Mutsuo

    In this paper, the single-phase static VAR compensator (SVC) is applied to regulate and stabilize smoothly the generated output voltage of the single-phase self-excited induction generator (single-phase SEIG) driven by a variable-speed prime mover (VSPM) under the conditions of inductive load variations and prime mover speed changes. The conventional fixed gain PI controller-based feedback control scheme is employed to adjust the equivalent capacitance of the single-phase SVC composed of the fixed excitation capacitor (FC) in parallel with the thyristor switched capacitor (TSC) and the thyristor controlled reactor TCR. A PI closed-loop feedback voltage control scheme based on the SVC for the single-phase SEIG coupled by a VSPM prototype set-up is established. The closed-loop feedback output voltage responses in the single-phase SEIG coupled by a VSPM with different inductive load variations using the single-phase SVC with the PI controller are considered and discussed herein. Based on the SVC with the PI controller closed-loop feedback voltage regulation scheme, the experimental results for the single-phase SEIG driven by a VSPM are illustrated and proved its practical effectiveness in terms of the fast response and the high performances.

  9. Cooperative photoinduced metastable phase control in strained manganite films

    Science.gov (United States)

    Zhang, Jingdi; Tan, Xuelian; Liu, Mengkun; Teitelbaum, S. W.; Post, K. W.; Jin, Feng; Nelson, K. A.; Basov, D. N.; Wu, Wenbin; Averitt, R. D.

    2016-09-01

    A major challenge in condensed-matter physics is active control of quantum phases. Dynamic control with pulsed electromagnetic fields can overcome energetic barriers, enabling access to transient or metastable states that are not thermally accessible. Here we demonstrate strain-engineered tuning of La2/3Ca1/3MnO3 into an emergent charge-ordered insulating phase with extreme photo-susceptibility, where even a single optical pulse can initiate a transition to a long-lived metastable hidden metallic phase. Comprehensive single-shot pulsed excitation measurements demonstrate that the transition is cooperative and ultrafast, requiring a critical absorbed photon density to activate local charge excitations that mediate magnetic-lattice coupling that, in turn, stabilize the metallic phase. These results reveal that strain engineering can tune emergent functionality towards proximal macroscopic states to enable dynamic ultrafast optical phase switching and control.

  10. Subwavelength nonlinear phase control and anomalous phase matching in plasmonic metasurfaces

    Science.gov (United States)

    Almeida, Euclides; Shalem, Guy; Prior, Yehiam

    2016-01-01

    Metasurfaces, and in particular those containing plasmonic-based metallic elements, constitute an attractive set of materials with a potential for replacing standard bulky optical elements. In recent years, increasing attention has been focused on their nonlinear optical properties, particularly in the context of second and third harmonic generation and beam steering by phase gratings. Here, we harness the full phase control enabled by subwavelength plasmonic elements to demonstrate a unique metasurface phase matching that is required for efficient nonlinear processes. We discuss the difference between scattering by a grating and by subwavelength phase-gradient elements. We show that for such interfaces an anomalous phase-matching condition prevails, which is the nonlinear analogue of the generalized Snell's law. The subwavelength phase control of optical nonlinearities paves the way for the design of ultrathin, flat nonlinear optical elements. We demonstrate nonlinear metasurface lenses, which act both as generators and as manipulators of the frequency-converted signal.

  11. Control of Single-Stage Single-Phase PV inverter

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented....... The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; - the input power control using the dc voltage controller and power feed......-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter....

  12. Nonlinear Control of Heart Rate Variability in Human Infants

    Science.gov (United States)

    Sugihara, George; Allan, Walter; Sobel, Daniel; Allan, Kenneth D.

    1996-03-01

    Nonlinear analyses of infant heart rhythms reveal a marked rise in the complexity of the electrocardiogram with maturation. We find that normal mature infants (gestation >= 35 weeks) have complex and distinctly nonlinear heart rhythms (consistent with recent reports for healthy adults) but that such nonlinearity is lacking in preterm infants (gestation parasympathetic-sympathetic interaction and function are presumed to be less well developed. Our study further shows that infants with clinical brain death and those treated with atropine exhibit a similar lack of nonlinear feedback control. These three lines of evidence support the hypothesis championed by Goldberger et al. [Goldberger, A. L., Rigney, D. R. & West, B. J. (1990) Sci. Am. 262, 43-49] that autonomic nervous system control underlies the nonlinearity and possible chaos of normal heart rhythms. This report demonstrates the acquisition of nonlinear heart rate dynamics and possible chaos in developing human infants and its loss in brain death and with the administration of atropine. It parallels earlier work documenting changes in the variability of heart rhythms in each of these cases and suggests that nonlinearity may provide additional power in characterizing physiological states.

  13. S-variable approach to LMI-based robust control

    CERN Document Server

    Ebihara, Yoshio; Arzelier, Denis

    2015-01-01

    This book shows how the use of S-variables (SVs) in enhancing the range of problems that can be addressed with the already-versatile linear matrix inequality (LMI) approach to control can, in many cases, be put on a more unified, methodical footing. Beginning with the fundamentals of the SV approach, the text shows how the basic idea can be used for each problem (and when it should not be employed at all). The specific adaptations of the method necessitated by each problem are also detailed. The problems dealt with in the book have the common traits that: analytic closed-form solutions are not available; and LMIs can be applied to produce numerical solutions with a certain amount of conservatism. Typical examples are robustness analysis of linear systems affected by parametric uncertainties and the synthesis of a linear controller satisfying multiple, often  conflicting, design specifications. For problems in which LMI methods produce conservative results, the SV approach is shown to achieve greater accuracy...

  14. Self-coherent phase reference sharing for continuous-variable quantum key distribution

    Science.gov (United States)

    Marie, Adrien; Alléaume, Romain

    2017-01-01

    We develop a comprehensive framework to model and optimize the performance of continuous-variable quantum key distribution (CV-QKD) with a local local oscillator (LLO), when phase reference sharing and QKD are jointly implemented. We first analyze the limitations of the only existing approach, called LLO-sequential, and show that it requires high modulation dynamics and can only tolerate small phase noise. Our main contribution is to introduce two designs to perform LLO CV-QKD, respectively called LLO-delayline and LLO-displacement, and to study their performance. Both designs rely on a self-coherent approach, in which phase reference information and quantum information are coherently obtained from a single optical wavefront. We show that these designs can lift some limitations of the existing LLO-sequential approach. The LLO-delayline design can in particular tolerate much stronger phase noise and thus appears to be an appealing alternative to LLO-sequential in terms of network integrability. We also investigate, with the LLO-displacement design, how phase reference information and quantum information can be multiplexed within a single optical pulse. By studying the trade-off between phase reference recovery and phase noise induced by displacement, we, however, demonstrate that this design can only tolerate low phase noise. On the other hand, the LLO-displacement design has the advantage of minimal hardware requirements and provides a simple approach to multiplex classical and quantum communications, opening a practical path towards the development of ubiquitous coherent classical-quantum communications systems compatible with next-generation network requirements.

  15. Electrospinning of PVDF nanofibrous membranes with controllable crystalline phases

    Science.gov (United States)

    Lei, Tingping; Zhu, Ping; Cai, Xiaomei; Yang, Le; Yang, Fan

    2015-07-01

    Effectively controlling crystalline phases of electrospun polyvinylidene fluoride (PVDF) nanofibers is crucial to produce membranes with special properties for specific applications. Here, the heating treatment during or after electrospinning has been investigated to determine an effective way to control crystalline phase of PVDF nanofibers. By simultaneously controlling the collector temperature and the flow rate during the fiber deposition, a comparatively lower temperature (≤70 °C) is required for obtaining α-, β-, or γ-phase-dominant nanofibrous membranes, whereas a much higher temperature (≥150 °C) is necessary for post-heating of already-deposited fibers. On the other hand, through finely tuning the heating during or after electrospinning, crosslinked nanofibrous membranes can be also obtained, which undoubtedly enhance mechanical performance of the membranes. Therefore, it is hopeful to fabricate high-performance electrospun PVDF nanofibrous membranes with synchronous control of crystalline phases and morphologies, which will further broaden the applications of PVDF materials.

  16. Controlled Phase Gate Based on an Electron Floating on Helium

    Institute of Scientific and Technical Information of China (English)

    SHI Yan-Li; MEI Feng; YU Ya-Fei; ZHANG Zhi-Ming

    2011-01-01

    We propose a scheme to generate the controlled phase gate by using an electron floating on liquid helium. The electron is also driven by a classical laser beam and by an oscillating magnetic field. In the process, the vibration of the electron is used as the qubus to couple the energy level qubit (1D Stark-shifted hydrogen) and spin qubit Ultimately. the controlled phase gate can be generated.%@@ We propose a scheme to generate the controlled phase gate by using an electron floating on liquid helium.The electron is also driven by a classical laser beam and by an oscillating magnetic field.In the process,the vibration of the electron is used as the qubus to couple the energy level qubit(1D Stark-shifted hydrogen) and spin qubit.Ultimately,the controlled phase gate can be generated.

  17. Couplage variable entre un qubit de charge et un qubit de phase

    OpenAIRE

    Fay, Aurélien

    2008-01-01

    We have studied the quantum dynamics of a superconducting circuit based on a dc-SQUID coupled to a highly asymmetric Cooper pair transistor (ACPT). The dc-SQUID is a phase qubit controlled by a bias current and magnetic field. The ACPT is a charge qubit controlled by a bias current, magnetic flux and gate voltage. We have measured by microwave spectroscopy the lowest quantum levels of the coupled circuit as a function of the bias parameters. Quantum state measurements of the phase and charge ...

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  19. Variable phase propagation velocity for long-range lightning location system

    Science.gov (United States)

    Liu, Zhongjian; Koh, Kuang Liang; Mezentsev, Andrew; Enno, Sven-Erik; Sugier, Jacqueline; Füllekrug, Martin

    2016-11-01

    The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for lightning location systems that use time of arrival (TOA) method. This velocity is normally fixed at or near the speed of light. However, this study finds that the radio waves from two submarine communication transmitters at 20.9 kHz and 23.4 kHz exhibit phase propagation velocities that are 0.51% slower and 0.64% faster than the speed of light as a result of sky wave contributions and ground effects. Therefore, a novel technique with a variable phase propagation velocity is implemented for the first time in the TOA method and applied to electric field recordings with a long-baseline lightning location system that consists of four radio receivers in western Europe. The lightning locations inferred from variable velocities improve the accuracy of locations inferred from a fixed velocity by 0.89-1.06 km when compared to the lightning locations reported by the UK MetOffice. The normal distributions of the observed phase propagation velocities in small geographic areas are not centered at the speed of light. Consequently, representative velocities can be calculated for many small geographic areas to produce a velocity map over central France where numerous lightning discharges occurred. This map reflects the impact of sky waves and ground effects on the calculation of lightning locations as a result of the network configuration. It is concluded that the use of variable phase propagation velocities mitigates the influence of sky waves and ground effects in long-range lightning location networks.

  20. Fuzzy Logic Based Speed Control System for ThreePhase Induction Motor

    Directory of Open Access Journals (Sweden)

    Marwan A. Badran

    2013-05-01

    Full Text Available Three-phase induction motors have been used in a wide range of industry applications. Using modern technology, the speed of induction motor can be easily controlled by variable frequency drives (VFDs. These drives use high speed power transistors with various switching techniques, mainly PWM schemes. For several decades, conventional control systems were applied to electric drives to control the speed of induction motor. Although conventional controllers showed good results, but they still need tuning to obtain optimum results. The recent proposed control systems use fuzzy logic controller (FLC to enhance the performance of induction motor drives. In this paper, a fuzzy logic based speed control system is presented. The proposed controller has been designed with MATLAB/SIMULINK software, and it was tested for various operating conditions including load disturbance and sudden change of reference speed. The results showed better performance of the proposed controller compared with the conventional PI controller.

  1. Climate variability during warm and cold phases of the Atlantic Multidecadal Oscillation (AMO) 1871-2008

    Science.gov (United States)

    Alexander, Michael A.; Halimeda Kilbourne, K.; Nye, Janet A.

    2014-05-01

    An extended reanalysis, a combination of observations and model output, is used to examine the spatial patterns of physical variables associated with the Atlantic Multidecadal Oscillation (AMO) from 1871 to 2008. The results are presented as anomalies during positive and negative phases of the AMO. As in previous studies, during positive (negative) AMO phases the sea surface temperature (SST) is anomalously warm (cold) over most of the North Atlantic, with the exception of the east coast of the United States. The atmospheric patterns, associated with the positive phase of the AMO, include anomalous low pressure over the Atlantic between 20°S and 50°N, cyclonic surface winds around the low, reduced wind speeds over the tropical Atlantic and enhanced precipitation in the eastern tropical Atlantic, with roughly opposite conditions during negative AMO phases. There are, however, substantial differences in the SST and the atmospheric anomalies between periods of the same phase, especially in the extratropics. Correlations between the AMO and air temperature anomalies are positive over much of the globe between 40°S and 50°N, with correlations exceeding 0.6 (~ 95% significance level) over the Maritime Continent and northern rim of the Pacific Ocean. Most of the sea level pressure (SLP) anomalies beyond the Atlantic are not statistically significant.

  2. SPS phase control system performance via analytical simulation

    Science.gov (United States)

    Lindsey, W. C.; Kantak, A. V.; Chie, C. M.; Booth, R. W. D.

    1979-01-01

    A solar power satellite transmission system which incorporates automatic beam forming, steering, and phase control is discussed. The phase control concept centers around the notation of an active retrodirective phased array as a means of pointing the beam to the appropriate spot on Earth. The transmitting antenna (spacetenna) directs the high power beam so that it focuses on the ground-based receiving antenna (rectenna). A combination of analysis and computerized simulation was conducted to determine the far field performance of the reference distribution system, and the beam forming and microwave power generating systems.

  3. Phase Coexistence in Gallium Nanoparticles Controlled by Electron Excitation

    Science.gov (United States)

    Pochon, S.; MacDonald, K. F.; Knize, R. J.; Zheludev, N. I.

    2004-04-01

    In gallium nanoparticles 100nm in diameter grown on the tip of an optical fiber from an atomic beam we observed equilibrium coexistence of γ, β, and liquid structural phases that can be controlled by e-beam excitation in a highly reversible and reproducible fashion. With 2keV electrons only 1pJ of excitation energy per nanoparticle is needed to exercise control, with the equilibrium phase achieved in less than a few tenths of a microsecond. The transformations between coexisting phases are accompanied by a continuous change in the nanoparticle film's reflectivity.

  4. A Simplified Theory of Coupled Oscillator Array Phase Control

    Science.gov (United States)

    Pogorzelski, R. J.; York, R. A.

    1997-01-01

    Linear and planar arrays of coupled oscillators have been proposed as means of achieving high power rf sources through coherent spatial power combining. In such - applications, a uniform phase distribution over the aperture is desired. However, it has been shown that by detuning some of the oscillators away from the oscillation frequency of the ensemble of oscillators, one may achieve other useful aperture phase distributions. Notable among these are linear phase distributions resulting in steering of the output rf beam away from the broadside direction. The theory describing the operation of such arrays of coupled oscillators is quite complicated since the phenomena involved are inherently nonlinear. This has made it difficult to develop an intuitive understanding of the impact of oscillator tuning on phase control and has thus impeded practical application. In this work a simpl!fied theory is developed which facilitates intuitive understanding by establishing an analog of the phase control problem in terms of electrostatics.

  5. Reduced phase error through optimized control of a superconducting qubit

    CERN Document Server

    Lucero, Erik; Bialczak, Radoslaw C; Lenander, Mike; Mariantoni, Matteo; Neeley, Matthew; O'Connell, A D; Sank, Daniel; Wang, H; Weides, Martin; Wenner, James; Yamamoto, Tsuyoshi; Cleland, A N; Martinis, John

    2010-01-01

    Minimizing phase and other errors in experimental quantum gates allows higher fidelity quantum processing. To quantify and correct for phase errors in particular, we have developed a new experimental metrology --- amplified phase error (APE) pulses --- that amplifies and helps identify phase errors in general multi-level qubit architectures. In order to correct for both phase and amplitude errors specific to virtual transitions and leakage outside of the qubit manifold, we implement "half derivative" an experimental simplification of derivative reduction by adiabatic gate (DRAG) control theory. The phase errors are lowered by about a factor of five using this method to $\\sim 1.6^{\\circ}$ per gate, and can be tuned to zero. Leakage outside the qubit manifold, to the qubit $|2\\rangle$ state, is also reduced to $\\sim 10^{-4}$ for $20\\%$ faster gates.

  6. From precipitation to runoff: Climatic controls on discharge variability

    Science.gov (United States)

    Rossi, M. W.; Whipple, K. X.; Vivoni, E. R.

    2012-12-01

    A number of recent studies have stressed the importance of modeling stochastic distributions of flood magnitudes along with thresholds to incision in order to develop more robust predictions of climatic control on fluvial erosion. Some of these studies have used precipitation time-series and others have used discharge time-series to characterize the climate state. While discharge is more directly tied to incision process, precipitation records are generally of longer duration and are more widely available. However, before fluvial incision models can benefit from the wealth of global precipitation data, better understanding of the non-linear transformation from precipitation to runoff is needed. There are a number of possible explanations for this non-linearity that can be broadly characterized into: (1) the statistical structure of precipitation itself (e.g. the autocorrelation of precipitation events); (2) the mediation of rainfall to runoff by the soil water balance (e.g. the role of soil properties and vegetation); and (3) the spatial organization of channel networks. While progress is needed on each of these fronts, we choose to first focus on (1) by examining the statistics of mean daily storm depth, storm frequency, and runoff for the continental U.S. The continental U.S. provides a good setting to explore this issue because it exhibits a wide range of climates (dry to humid; cold to hot; winter-dominated to summer-dominated precipitation) and has a dense observation network for both precipitation and discharge. Specifically, we rely on the United States Historical Climatology Network (USHCN) for meteorological data (1,221 stations) and the Hydro-Climatic Data Network-2009 (HCDN-2009) for hydrological data (704 stations). Stations in these networks have been selected to best reflect the "natural" state by maximizing record length/completeness and minimizing anthropogenic influence. Whereas precipitation is commonly modeled as a Poisson process (i.e. an

  7. Is Regional Root Reinforcement Controlled by Soil Moisture Variability?

    Science.gov (United States)

    Hales, T.; Ford, C. R.

    2011-12-01

    of "bound water" (water present in the cell wall), which in turn affected the strength of the cellulose fibrils that provide tensile strength. This phenomenon, which is the reason any wet wood is weaker than dry wood, results in a 50% difference in root tensile strength within the range of soil moisture measured in the field. We used a one-dimensional finite difference model to explore the effects of soil moisture on root cohesion. Our model shows that changes in the distribution of root biomass represent the primary control on root cohesion (representing up to 50% of intra-specific variability in root cohesion). Local changes in soil moisture result in ~20% change in the overall root cohesion. Our work suggest a feed-forward process in precipitation (and thus soil moisture), root strength changes, and debris flow hazard.

  8. Distributed Adaptive Control: Beyond Single-Instant, Discrete Variables

    Science.gov (United States)

    Wolpert, David H.; Bieniawski, Stefan

    2005-01-01

    In extensive form noncooperative game theory, at each instant t, each agent i sets its state x, independently of the other agents, by sampling an associated distribution, q(sub i)(x(sub i)). The coupling between the agents arises in the joint evolution of those distributions. Distributed control problems can be cast the same way. In those problems the system designer sets aspects of the joint evolution of the distributions to try to optimize the goal for the overall system. Now information theory tells us what the separate q(sub i) of the agents are most likely to be if the system were to have a particular expected value of the objective function G(x(sub 1),x(sub 2), ...). So one can view the job of the system designer as speeding an iterative process. Each step of that process starts with a specified value of E(G), and the convergence of the q(sub i) to the most likely set of distributions consistent with that value. After this the target value for E(sub q)(G) is lowered, and then the process repeats. Previous work has elaborated many schemes for implementing this process when the underlying variables x(sub i) all have a finite number of possible values and G does not extend to multiple instants in time. That work also is based on a fixed mapping from agents to control devices, so that the the statistical independence of the agents' moves means independence of the device states. This paper also extends that work to relax all of these restrictions. This extends the applicability of that work to include continuous spaces and Reinforcement Learning. This paper also elaborates how some of that earlier work can be viewed as a first-principles justification of evolution-based search algorithms.

  9. No-moving-parts phase flattening based Laguerre-Gauss (LG) spectrometer using variable focus lenses

    CERN Document Server

    Sheikh, Mumtaz; Rathore, Haad Yaqub

    2016-01-01

    We address some of the limitations of the classical projective, phase flattening technique for measuring the Laguerre-Gauss (LG) spectrum of light beams. In particular, we propose the use of two variable focus lenses and a variable sized pinhole to realize a no-moving-parts LG spectrometer with virtually zero coupling losses. Simulation results show that the only losses are ring losses which are mode-dependent but beam waist-independent. Hence, the detection efficiency for all modes is simultaneously the maximum possible irrespective of the beam waist of the LG modes chosen for the decomposition. The losses can also be easily pre-calibrated to remove the small efficiency bias amongst different modes.

  10. Spacecraft Pointing Control Using a Variable-Speed Control Moment Gyro

    Science.gov (United States)

    Yamada, Katsuhiko; Takatsuka, Naoki; Shima, Takeya

    The objective of this study is to align a certain axis of a spacecraft in an arbitrary direction by using a variable-speed single-gimbal CMG. Because the total angular momentum of the spacecraft is conserved in inertial space, the final attitude of the spacecraft is restricted, and it is possible to achieve pointing control of the axis that is orthogonal to the gimbal axis. Using new parameters to express pointing errors, we have proposed a simple pointing control law that can be used to align the pointing axis in an arbitrary direction in inertial space. The validity of the proposed control law is verified by numerical simulations.

  11. Phase-sensitive cascaded four-wave mixing processes for generating continuous-variable entanglement.

    Science.gov (United States)

    Wang, Li; Jing, Jietai

    2017-03-20

    Quantum entanglement shared by different parties enhances their capabilities to communicate, which is the core content of continuous-variable quantum optics and quantum information science. Here, we study an experimentally feasible scheme for generating quantum entanglement of bipartite and tripartite cases based on phase-sensitive cascaded four-wave mixing processes in rubidium vapor. Quantum entanglement of bipartite and tripartite cases in our system, which can be manipulated by the phases and the intensity gains of the input beams, is predicted. We also find a sufficient optimal single-condition criterion to give a valid description for genuine tripartite quantum entanglement in our system. The sufficient optimal single-condition criterion is convenient and can be extended to genuine multipartite entanglement.

  12. Dose dependency and individual variability of the lipopolysaccharide-induced bovine acute phase protein response

    DEFF Research Database (Denmark)

    Jacobsen, S.; Andersen, P.H.; Tølbøll, T.

    2004-01-01

    In order to investigate the dose dependency and the individual variability of the lipopolysaccharide (LPS)-induced acute phase protein response in cattle, 8 nonlactating, nonpregnant Danish Holstein cows were challenged 3 times each by intravenous injection of increasing doses (10, 100, and 1000 ng...... for several days after each LPS injection, and their increase or decrease was significantly related to LPS dose. In addition to dose dependency, the response was also dependent on the individual, as APP concentrations differed significantly among cows. To compare APP production in 2 consecutive challenges...

  13. Continuous controllable amorphization ratio of nanoscale phase change memory cells

    Science.gov (United States)

    He, Q.; Li, Z.; Peng, J. H.; Deng, Y. F.; Zeng, B. J.; Zhou, W.; Miao, X. S.

    2014-06-01

    The controllable heat behavior, including heat generation and dissipation, is one of the most important physical problems of nanoscale phase-change memory (PCM). A method based on heat accumulation effect to control heat behavior by synthetically modulating the three parameters of applied double pulses is proposed to achieve any expected amorphization ratio. A compact model of nanoscale PCM cells is used to simulate the thermal behavior and amorphization ratio under the condition of single parameter and multi-parameter change of applied double pulses. The results are in good agreement with the experimental results. Repeated experiments also prove the feasibility of continuous controllable amorphization ratio of nanoscale phase-change materials.

  14. Decoupling Control Strategy for Single Phase SPWM Parallel Inverters

    Institute of Scientific and Technical Information of China (English)

    Shun-Gang Xu; Jian-Ping Xu; Tai-Qiang Cao

    2009-01-01

    A decoupling control strategy of inverter parallel system is proposed based on the equivalent output impedance of single phase voltage source SPWM (sinusoidal pulse width modulation) inverter. The active power and reactive power are calculated in terms of output voltage and current of the inverter, and sent to the other inverters in the parallel system via controller area network (CAN) bus. By calculating and decoupling the circumfluence of the active power and reactive power, the inverters can share load current via the regulation of the reference-signal phase and amplitude. Experimental results of an 110V/2kVA inverter parallel system show the feasibility of the decoupling control strategy.

  15. H∞ Robust Controller Design for an Induction Generator Driven by a Variable-Speed Wind Turbine

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Hoseini

    2011-01-01

    Full Text Available This paper presents the modeling and robust controller design design for a wind-driven induction generator system. a  robust controller for the static synchronous compensator (STATCOM and the variable blade pitch in a wind energy conversion system (WECS is designed to be controlled voltage and mechanical power. This controller leading to satisfactory damping characteristics achieved for the closed loop system. Effects of various system disturbances on the dynamic performance have been simulated, and the results comparison with output feedback controller reveal that the proposed controller is effective in regulating the load voltage and stabilizing the generator rotating speed for WECS. The nonlinear simulation was conducted and that comparison with the above linear simulation shows that the simulations carried out for small changes in system inputs is sufficiently accurate. For review performance against large disturbances from a symmetrical three-phase short circuit at infinity bus bar has been used  and the results show robust controller design as well as fluctuations resulting from the short circuit is damped.

  16. Nonlinear model-based control of the Czochralski process III: Proper choice of manipulated variables and controller parameter scheduling

    Science.gov (United States)

    Neubert, M.; Winkler, J.

    2012-12-01

    This contribution continues an article series [1,2] about the nonlinear model-based control of the Czochralski crystal growth process. The key idea of the presented approach is to use a sophisticated combination of nonlinear model-based and conventional (linear) PI controllers for tracking of both, crystal radius and growth rate. Using heater power and pulling speed as manipulated variables several controller structures are possible. The present part tries to systematize the properties of the materials to be grown in order to get unambiguous decision criteria for a most profitable choice of the controller structure. For this purpose a material specific constant M called interface mobility and a more process specific constant S called system response number are introduced. While the first one summarizes important material properties like thermal conductivity and latent heat the latter one characterizes the process by evaluating the average axial thermal gradients at the phase boundary and the actual growth rate at which the crystal is grown. Furthermore these characteristic numbers are useful for establishing a scheduling strategy for the PI controller parameters in order to improve the controller performance. Finally, both numbers give a better understanding of the general thermal system dynamics of the Czochralski technique.

  17. Touch Screen based Speed Control of Single Phase Induction Motor

    Directory of Open Access Journals (Sweden)

    S. Mallika

    2010-12-01

    Full Text Available This paper gives a brief idea of touch screen technology and its interfacing with a controller to control the speed of single phase induction motor. Here touch screen technology and Programmable System on Chip (PSOC microcontroller concept is utilized which is less spaceconsumption and easy to design. The aim of this paper is to have remote sensing and speed control of an AC motor.

  18. Predictors of Performance in Introductory Finance: Variables within and beyond the Student's Control

    Science.gov (United States)

    Englander, Fred; Wang, Zhaobo; Betz, Kenneth

    2015-01-01

    This study examined variables that are within and beyond the control of students in explaining variations in performance in an introductory finance course. Regression models were utilized to consider whether the variables within the student's control have a greater impact on course performance relative to the variables beyond the student's…

  19. Attitude control of a rigid spacecraft with one variable-speed control moment gyro

    Science.gov (United States)

    Gui, Hai-Chao; Jin, Lei; Xu, Shi-Jie

    2013-10-01

    Nonlinear controllability and attitude stabilization are studied for the underactuated nonholonomic dynamics of a rigid spacecraft with one variable-speed control moment gyro (VSCMG), which supplies only two internal torques. Nonlinear controllability theory is used to show that the dynamics are locally controllable from the equilibrium point and thus can be asymptotically stabilized to the equilibrium point via time-invariant piecewise continuous feedback laws or time-periodic continuous feedback laws. Specifically, when the total angular momentum of the spacecraft-VSCMG system is zero, any orientation can be a controllable equilibrium attitude. In this case, the attitude stabilization problem is addressed by designing a kinematic stabilizing law, which is implemented through a nonlinear proportional and derivative controller, using the generalized dynamic inverse (GDI) method. The steady-state instability inherent in the GDI controller is elegantly avoided by appropriately choosing control gains. In order to obtain the command gimbal rate and wheel acceleration from control torques, a simple steering logic is constructed to accommodate the requirements of attitude stabilization and singularity avoidance of the VSCMG. Illustrative numerical examples verify the efficacy of the proposed control strategy.

  20. Spatial variability of enthalpy in broiler house during the heating phase

    Directory of Open Access Journals (Sweden)

    Patrícia F. P. Ferraz

    2016-06-01

    Full Text Available ABSTRACT The thermal environment inside a broiler house has a great influence on animal welfare and productivity during the production phase. Enthalpy is a thermodynamic property that has been proposed to evaluate the internal broiler house environment, for being an indicator of the amount of energy contained in a mixture of water vapor and dry air. Therefore, this study aimed to characterize the spatial variability of enthalpy in a broiler house during the heating phase using geostatistics. The experiment was conducted in the spring season, in a commercial broiler house with heating system consisting of two furnaces that heat the air indirectly, in the first 14 days of the birds' life. It was possible to characterize enthalpy variability using geostatistical techniques, which allowed observing the spatial dependence through kriging maps. The analyses of the maps allowed observing problems in the heating system in regions inside the broiler house, which may cause a thermal discomfort to the animals besides productive and economic losses.

  1. Color variability of HBC 722 in the post-outburst phases

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Giseon; Pak, Soojong; Lee, Jeong-Eun [School of Space Research and Institute of Natural Sciences, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Green, Joel D.; Meschiari, Stefano [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Jeon, Yiseul; Choi, Changsu; Im, Myungshin [CEOU/Department of Physics and Astronomy, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Sung, Hyun-Il; Park, Won-Kee [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

    2015-02-01

    We carried out photometric observations for HBC 722 in the Sloan Digital Sky Survey r, i, and z bands from 2011 April to 2013 May with the Camera for QUasars in EArly uNiverse attached to the 2.1 m Otto Struve telescope at McDonald Observatory. The post-outburst phenomena were classified into five phases according to not only brightness but also color variations, which might be caused by physical changes in the emitting regions of optical and near-infrared bands. A series of spectral energy distributions (SEDs) is presented to support color variations and track the time evolution of the SED in optical/near-infrared bands after the outburst. Given two years of data, possible periodicities of r, i, and z bands were checked. We found three families of signals around ∼6, ∼10, and ∼1 days in three bands, which is broadly consistent with Green et al. We also examined short-term variability (intra-day and day scales) to search for evidences of flickering by using the micro-variability method. We found clear signs of day scale variability and weak indications of intra-day scale fluctuations, which implies that the flickering event occurs in HBC 722 after outburst.

  2. Discretization of control law for a class of variable structure control systems

    OpenAIRE

    Golo, G.; Schaft, van der, Arjan; Milosavljević, Č.

    2000-01-01

    A new method for the discretization of a class of continuous-time variable structure control systems, based on the linear complementarity theory, is proposed. The proposed method consists two steps. In the first step, the motion projected on the sliding manifold (the fast dynamics) is discretized by means of backward Euler time-step method. In the second step, the sampled and hold control law is determined such that the trajectories of the discrete-time closed loop system projected on the sli...

  3. Insights into gait disorders: walking variability using phase plot analysis, Parkinson's disease.

    Science.gov (United States)

    Esser, Patrick; Dawes, Helen; Collett, Johnny; Howells, Ken

    2013-09-01

    Gait variability may have greater utility than spatio-temporal parameters and can, be an indication for risk of falling in people with Parkinson's disease (PD). Current methods rely on prolonged data collection in order to obtain large datasets which may be demanding to obtain. We set out to explore a phase plot variability analysis to differentiate typically developed adults (TDAs) from PD obtained from two 10 m walks. Fourteen people with PD and good mobility (Rivermead Mobility Index≥8) and ten aged matched TDA were recruited and walked over 10-m at self-selected walking speed. An inertial measurement unit was placed over the projected centre of mass (CoM) sampling at 100 Hz. Vertical CoM excursion was derived to determine modelled spatiotemporal data after which the phase plot analysis was applied producing a cloud of datapoints. SDA described the spread and SDB the width of the cloud with β the angular vector of the data points. The ratio (∀) was defined as SDA: SDB. Cadence (p=.342) and stride length (p=.615) did not show a significance between TDA and PD. A difference was found for walking speed (p=.041). Furthermore a significant difference was found for β (p=.010), SDA (p=.004) other than SDB (p=.385) or ratio ∀ (p=.830). Two sequential 10-m walks showed no difference in PD for cadence (p=.193), stride length (p=.683), walking speed (p=.684) and β (p=.194), SDA (p=.051), SDB (p=.145) or ∀ (p=.226). The proposed phase plot analysis, performed on CoM motion could be used to reliably differentiate PD from TDA over a 10-m walk.

  4. New fuzzy EWMA control charts for monitoring phase II fuzzy profiles

    Directory of Open Access Journals (Sweden)

    Ghazale Moghadam

    2016-01-01

    Full Text Available In many quality control applications, the quality of a process or product is explained by the relationship between response variable and one or more explanatory variables, called a profile. In this paper, a new fuzzy EWMA control chart for phase II fuzzy profile monitoring is proposed. To this end, we extend EWMA control charts to its equivalent Fuzzy type and then implement fuzzy ranking methods to determine whether the process fuzzy profile is under or out of control. The proposed method is capable of identifying small changes in process under condition of process profile explaining parameters vagueness, roughness and uncertainty. Determining the source of changes, this method provides us with the possibility of recognizing the causes of process transition from stable mode, removing these causes and restoring the process stable mode.

  5. Inductor Compensation in Three Phase PFC Control with Decoupling the Input Voltage and Bus Voltage

    Directory of Open Access Journals (Sweden)

    Luo Guang

    2016-01-01

    Full Text Available As the nonlinear structure of the boost ac/dc topology, the PFC is difficult to be controlled. The average state space theory has revealed that the choke current is determined by duty-ratio coupled with input voltage and bus voltage, which makes the high-performance sine-wave current track control more challenging. To remove disturbing variables and reduce the zero-crossing distortion, the decoupling control strategy is presented. Also, it is shown in this paper that the variable inductance has a great influence on PFC and THDI. As the inductor in boost converter varies with the current, a compensating coefficient of current is also proposed. The decoupling strategy and the inductor compensation strategy are implemented on a UPS with three phase input voltage. Numerical simulation and experimental results has indicated the high-performance of these control strategy.

  6. Fully controlled 5-phase, 10-pulse, line commutated rectifier

    Directory of Open Access Journals (Sweden)

    Mahmoud I. Masoud

    2015-12-01

    Full Text Available The development and production of multiphase machines either generators or motors, specially five-phase, offers improved performance compared to three-phase counterpart. Five phase generators could generate power in applications such as, but not limited to, wind power generation, electric vehicles, aerospace, and oil and gas. The five-phase generator output requires converter system such as ac–dc converters. In this paper, a fully controlled 10-pulse line commutated rectifier, suitable to be engaged with wind energy applications, fed from five-phase source is introduced. A shunt active power filter (APF is used to improve power factor and supply current total harmonic distortion (THD. Compared to three-phase converters, 6-pulse or 12-pulse rectifiers, the 10-pulse rectifier engaged with 5-phase source alleviate their drawbacks such as high dc ripples and no need for electric gear or phase shifting transformer. MATLAB/SIMULINK platform is used as a simulation tool to investigate the performance of the proposed rectifier.

  7. Control of the spin geometric phase in semiconductor quantum rings

    Science.gov (United States)

    Nagasawa, Fumiya; Frustaglia, Diego; Saarikoski, Henri; Richter, Klaus; Nitta, Junsaku

    2013-09-01

    Since the formulation of the geometric phase by Berry, its relevance has been demonstrated in a large variety of physical systems. However, a geometric phase of the most fundamental spin-1/2 system, the electron spin, has not been observed directly and controlled independently from dynamical phases. Here we report experimental evidence on the manipulation of an electron spin through a purely geometric effect in an InGaAs-based quantum ring with Rashba spin-orbit coupling. By applying an in-plane magnetic field, a phase shift of the Aharonov-Casher interference pattern towards the small spin-orbit-coupling regions is observed. A perturbation theory for a one-dimensional Rashba ring under small in-plane fields reveals that the phase shift originates exclusively from the modulation of a pure geometric-phase component of the electron spin beyond the adiabatic limit, independently from dynamical phases. The phase shift is well reproduced by implementing two independent approaches, that is, perturbation theory and non-perturbative transport simulations.

  8. Variable Camber Continuous Aerodynamic Control Surfaces and Methods for Active Wing Shaping Control

    Science.gov (United States)

    Nguyen, Nhan T. (Inventor)

    2016-01-01

    An aerodynamic control apparatus for an air vehicle improves various aerodynamic performance metrics by employing multiple spanwise flap segments that jointly form a continuous or a piecewise continuous trailing edge to minimize drag induced by lift or vortices. At least one of the multiple spanwise flap segments includes a variable camber flap subsystem having multiple chordwise flap segments that may be independently actuated. Some embodiments also employ a continuous leading edge slat system that includes multiple spanwise slat segments, each of which has one or more chordwise slat segment. A method and an apparatus for implementing active control of a wing shape are also described and include the determination of desired lift distribution to determine the improved aerodynamic deflection of the wings. Flap deflections are determined and control signals are generated to actively control the wing shape to approximate the desired deflection.

  9. Attitude Control for an Aero-Vehicle Using Vector Thrusting and Variable Speed Control Moment Gyros

    Science.gov (United States)

    Shin, Jong-Yeob; Lim, K. B.; Moerder, D. D.

    2005-01-01

    Stabilization of passively unstable thrust-levitated vehicles can require significant control inputs. Although thrust vectoring is a straightforward choice for realizing these inputs, this may lead to difficulties discussed in the paper. This paper examines supplementing thrust vectoring with Variable-Speed Control Moment Gyroscopes (VSCMGs). The paper describes how to allocate VSCMGs and the vectored thrust mechanism for attitude stabilization in frequency domain and also shows trade-off between vectored thrust and VSCMGs. Using an H2 control synthesis methodology in LMI optimization, a feedback control law is designed for a thrust-levitated research vehicle and is simulated with the full nonlinear model. It is demonstrated that VSCMGs can reduce the use of vectored thrust variation for stabilizing the hovering platform in the presence of strong wind gusts.

  10. Maneuver and vibration control of flexible manipulators using variable-speed control moment gyros

    Science.gov (United States)

    Hu, Quan; Zhang, Jingrui

    2015-08-01

    In this paper, the variable-speed control moment gyros (VS-CMGs) are adopted as actuators for vibration suppression of space flexible manipulators. They are directly mounted on the flexible links of the manipulator. Such system can be viewed as a flexible multibody system in chain topology actuated by both joint motors and VS-CMGs. We first develop a general approach for establishing the system equations of motion through Kane's method. Then, two controllers are designed for trajectory tracking and vibration suppression: one is an inverse dynamics control, whereas the other is based on the singular perturbation method. The proposed two control strategies are applied to a free-flying platform with a flexible manipulator. Sample numerical results show that the VS-CMGs can significantly suppress the induced vibration of the flexible links during the large angle maneuver.

  11. Relationship between Lower Limb Angular Kinematic Variables and the Effectiveness of Sprinting during the Acceleration Phase

    Directory of Open Access Journals (Sweden)

    Artur Struzik

    2016-01-01

    Full Text Available The ability to reach a high running velocity over a short distance is essential to a high playing performance in team games. The aim of this study was to determine the relationship between running time over a 10-meter section of a 30-meter sprint along a straight line and changes in the angle and angular velocity that were observed in the ankle, knee, and hip joints. The possible presence may help to optimize motion efficiency during acceleration sprint phase. Eighteen girls involved in team sports were examined in the study. The Fusion Smart Speed System was employed for running time measurements. The kinematic data were recorded using the Noraxon MyoMotion system. Statistically significant relationships were found between running time over a 10-meter section and the kinematic variables of hip and ankle joints. An excessively large flexion in hip joints might have an unfavorable effect on running time during the acceleration phase. Furthermore, in order to minimize running time during the acceleration phase, stride should be maintained along a line (a straight line rather than from side to side. It is also necessary to ensure an adequate range of motion in the hip and ankle joints with respect to the sagittal axis.

  12. The numerical solution of thawing process in phase change slab using variable space grid technique

    Directory of Open Access Journals (Sweden)

    Serttikul, C.

    2007-09-01

    Full Text Available This paper focuses on the numerical analysis of melting process in phase change material which considers the moving boundary as the main parameter. In this study, pure ice slab and saturated porous packed bed are considered as the phase change material. The formulation of partial differential equations is performed consisting heat conduction equations in each phase and moving boundary equation (Stefan equation. The variable space grid method is then applied to these equations. The transient heat conduction equations and the Stefan condition are solved by using the finite difference method. A one-dimensional melting model is then validated against the available analytical solution. The effect of constant temperature heat source on melting rate and location of melting front at various times is studied in detail.It is found that the nonlinearity of melting rate occurs for a short time. The successful comparison with numerical solution and analytical solution should give confidence in the proposed mathematical treatment, and encourage the acceptance of this method as useful tool for exploring practical problems such as forming materials process, ice melting process, food preservation process and tissue preservation process.

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

    DEFF Research Database (Denmark)

    Lascu, Christian; Boldea, Ion; Blaabjerg, Frede

    2004-01-01

    A family of variable-structure controllers for induction machine drives is presented, in which the principles of direct torque control (DTC), variable-structure control (VSC) and space-vector pulsewidth modulation are combined to ensure high-performance operation, both in the steady state and under...

  14. A unified model-free controller for switching minimum phase, non-minimum phase and time-delay systems

    CERN Document Server

    Michel, Loïc

    2012-01-01

    This preliminary work presents a simple derivation of the standard model-free control in order to control switching minimum phase, non-minimum phase and time-delay systems. The robustness of the proposed method is studied in simulation.

  15. Energy constraints in pulsed phase control of chaos

    Science.gov (United States)

    Meucci, R.; Euzzor, S.; Zambrano, S.; Pugliese, E.; Francini, F.; Arecchi, F. T.

    2017-01-01

    Phase control of chaos is a powerful technique but little is known about its physical constraints, relevant for real systems. As a fact, it has not been explored whether this technique can also be applied when the controlling perturbation is not harmonic. Here we apply phase control on a driven double well Duffing oscillator using periodic rectangular pulsed perturbations instead of the classical sinusoidal perturbations. Experimental measurements and numerical simulations show that this kind of perturbation is also able to stabilize the chaotic orbits for an adequate selection of the phase. Furthermore, as the duty cycle of the perturbation (that is, the fraction of the time that the periodically pulsed control is active) is increased, two separate regimes occur. In the first one, the perturbations leading to stabilization of periodic solutions are of constant energy (taken as the product of the duty cycle and the amplitude) and in the second one, a saturation phenomenon occurs, implying that increasing energy values of the perturbations are wasted. Our results unveil the versatility of the pulsed phase control scheme and the importance of energy constraints.

  16. 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.

  17. Overall control strategy of variable speed doubly-fed induction generator wind turbine

    DEFF Research Database (Denmark)

    Hansen, A. D.; Soerensen, P.; Iov, Florin

    2004-01-01

    The variable speed doubly-fed induction generator wind turbine is today the most widely used concept. The paper presents an overall control system of the variable speed DFIG wind turbine, with focus on the control strategies and algorithms applied at each hierarchical control level of the wind tu...

  18. Study on chaos control of second-order non-autonomous phase-locked loop based on state observer

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yibo [College of physics and Electronic Information, Anhui Normal University, Wuhu 241000 (China)], E-mail: zhyb26@yahoo.com.cn; Wei Duqu; Luo Xiaoshu [College of Physics and Electronic engineering, Guangxi Normal University, Guilin 541004 (China)

    2009-02-28

    With system parameters falling into a certain area, the second-order non-autonomous phase locked loop (PLL) is experiencing chaotic behavior which is undesirable in system, where it is necessary to estimate the phase of a received signal. In order to control chaos in PLL and drive it to the locked state, dynamical equation for phase error model of PLL is firstly derived. Then, the state values of phase and transient frequency errors were estimated by a state observer. Moreover, by exploiting these state estimations, a non-linear feedback controller is designed. Since the presented controller does not need to change the controlled system structure and not to use any information of system except the system state variables, the designed controller is simple and desirable. Simulation results show that the presented control law is very effective.

  19. Which System Variables Carry Robust Early Signs of Upcoming Phase Transition? An Ecological Example

    Science.gov (United States)

    Negahbani, Ehsan; Steyn-Ross, D. Alistair; Steyn-Ross, Moira L.; Aguirre, Luis A.

    2016-01-01

    Growth of critical fluctuations prior to catastrophic state transition is generally regarded as a universal phenomenon, providing a valuable early warning signal in dynamical systems. Using an ecological fisheries model of three populations (juvenile prey J, adult prey A and predator P), a recent study has reported silent early warning signals obtained from P and A populations prior to saddle-node (SN) bifurcation, and thus concluded that early warning signals are not universal. By performing a full eigenvalue analysis of the same system we demonstrate that while J and P populations undergo SN bifurcation, A does not jump to a new state, so it is not expected to carry early warning signs. In contrast with the previous study, we capture a significant increase in the noise-induced fluctuations in the P population, but only on close approach to the bifurcation point; it is not clear why the P variance initially shows a decaying trend. Here we resolve this puzzle using observability measures from control theory. By computing the observability coefficient for the system from the recordings of each population considered one at a time, we are able to quantify their ability to describe changing internal dynamics. We demonstrate that precursor fluctuations are best observed using only the J variable, and also P variable if close to transition. Using observability analysis we are able to describe why a poorly observable variable (P) has poor forecasting capabilities although a full eigenvalue analysis shows that this variable undergoes a bifurcation. We conclude that observability analysis provides complementary information to identify the variables carrying early-warning signs about impending state transition. PMID:27631984

  20. Which System Variables Carry Robust Early Signs of Upcoming Phase Transition? An Ecological Example.

    Science.gov (United States)

    Negahbani, Ehsan; Steyn-Ross, D Alistair; Steyn-Ross, Moira L; Aguirre, Luis A

    2016-01-01

    Growth of critical fluctuations prior to catastrophic state transition is generally regarded as a universal phenomenon, providing a valuable early warning signal in dynamical systems. Using an ecological fisheries model of three populations (juvenile prey J, adult prey A and predator P), a recent study has reported silent early warning signals obtained from P and A populations prior to saddle-node (SN) bifurcation, and thus concluded that early warning signals are not universal. By performing a full eigenvalue analysis of the same system we demonstrate that while J and P populations undergo SN bifurcation, A does not jump to a new state, so it is not expected to carry early warning signs. In contrast with the previous study, we capture a significant increase in the noise-induced fluctuations in the P population, but only on close approach to the bifurcation point; it is not clear why the P variance initially shows a decaying trend. Here we resolve this puzzle using observability measures from control theory. By computing the observability coefficient for the system from the recordings of each population considered one at a time, we are able to quantify their ability to describe changing internal dynamics. We demonstrate that precursor fluctuations are best observed using only the J variable, and also P variable if close to transition. Using observability analysis we are able to describe why a poorly observable variable (P) has poor forecasting capabilities although a full eigenvalue analysis shows that this variable undergoes a bifurcation. We conclude that observability analysis provides complementary information to identify the variables carrying early-warning signs about impending state transition.

  1. On-Chip Flow Control for 2-PhaseNanofluidics

    NARCIS (Netherlands)

    Shui, Lingling; Berg, van den Albert; Eijkel, Jan C.T.; Kim, Tae Song; Lee, Yoon-Sik; Chung, Twek-Dong; Jeon, Noo Li; Lee, Sang-Hoon; Suh, Kahp-Yang; Choo, Jaebm; Kim, Yong-Kweon

    2009-01-01

    We developed a novel method to control two-phase flow in nanochannels using regulating microchannels connected to the nanochannels. The flow rate inside a nanochannel can be regulated based on the pressure drops along the channel network. Stable flows with flow rates as low as 10-5 µL.min-1 (< pL.s-

  2. Phase Change Permeation Technology For Environmental Control Life Support Systems

    Science.gov (United States)

    Wheeler, Raymond M.

    2014-01-01

    Use of a phase change permeation membrane (Dutyion [Trademark]) to passively and selectively mobilize water in microgravity to enable improved water recovery from urine/brine for Environment Control and Life Support Systems (ECLSS) and water delivery to plans for potential use in microgravity.

  3. Coherence control of pulse trains by spectral phase modulation

    Science.gov (United States)

    Ding, Chaoliang; Koivurova, Matias; Turunen, Jari; Setälä, Tero; Friberg, Ari T.

    2017-09-01

    We propose a technique to control the spectral and temporal coherence properties of pulsed beams of light via time-dependent manipulation of the spectral phase. Modulation schemes for the generation of partially coherent pulse trains from a train of fully coherent pulses are presented. The feasibility of experimental realization of the method is confirmed by numerical estimates.

  4. Phase controlled dc-ac converter with high frequency switching

    Science.gov (United States)

    Harada, Koosuke; Sakamoto, Hiroshi; Shoyama, Masahito

    A sinusoidal dc-ac converter is presented in which a pair of switches is placed on each side of the primary and secondary of the isolation transformer. This converter is controlled by the phase difference between the two pairs of switches. The transformer is miniaturized by making the switching frequency high. This converter is especially suitable for small uninterruptible power supply systems.

  5. Two-phase strategy of controlling motor coordination determined by task performance optimality.

    Science.gov (United States)

    Shimansky, Yury P; Rand, Miya K

    2013-02-01

    A quantitative model of optimal coordination between hand transport and grip aperture has been derived in our previous studies of reach-to-grasp movements without utilizing explicit knowledge of the optimality criterion or motor plant dynamics. The model's utility for experimental data analysis has been demonstrated. Here we show how to generalize this model for a broad class of reaching-type, goal-directed movements. The model allows for measuring the variability of motor coordination and studying its dependence on movement phase. The experimentally found characteristics of that dependence imply that execution noise is low and does not affect motor coordination significantly. From those characteristics it is inferred that the cost of neural computations required for information acquisition and processing is included in the criterion of task performance optimality as a function of precision demand for state estimation and decision making. The precision demand is an additional optimized control variable that regulates the amount of neurocomputational resources activated dynamically. It is shown that an optimal control strategy in this case comprises two different phases. During the initial phase, the cost of neural computations is significantly reduced at the expense of reducing the demand for their precision, which results in speed-accuracy tradeoff violation and significant inter-trial variability of motor coordination. During the final phase, neural computations and thus motor coordination are considerably more precise to reduce the cost of errors in making a contact with the target object. The generality of the optimal coordination model and the two-phase control strategy is illustrated on several diverse examples.

  6. A Generic Two-Phase Stochastic Variable Neighborhood Approach for Effectively Solving the Nurse Rostering Problem

    Directory of Open Access Journals (Sweden)

    Grigorios N. Beligiannis

    2013-05-01

    Full Text Available In this contribution, a generic two-phase stochastic variable neighborhood approach is applied to nurse rostering problems. The proposed algorithm is used for creating feasible and efficient nurse rosters for many different nurse rostering cases. In order to demonstrate the efficiency and generic applicability of the proposed approach, experiments with real-world input data coming from many different nurse rostering cases have been conducted. The nurse rostering instances used have significant differences in nature, structure, philosophy and the type of hard and soft constraints. Computational results show that the proposed algorithm performs better than six different existing approaches applied to the same nurse rostering input instances using the same evaluation criteria. In addition, in all cases, it manages to reach the best-known fitness achieved in the literature, and in one case, it manages to beat the best-known fitness achieved till now.

  7. Novel approach to protein crystallizations: Control of the phase behavior of aqueous solutions using microfluidics

    Science.gov (United States)

    Shim, Jung Uk

    A microfluidic device denoted the Phase Chip has been developed to exploit the permeation of water through poly(dimethylsiloxane) (PDMS) in order to vary the concentration of aqueous nanoliter volume microdrops stored in wells. The permeation of water in the Phase Chip is modeled using the diffusion equation and good agreement between experiment and theory is obtained. The phase diagram of a polymer/salt mixture is measured employing the Phase Chip and agrees well with the phase diagram obtained off-chip. The Phase Chip first creates drops of the polymer/salt mixture whose composition varies sequentially. Subsequently the drops are docked in storage wells and the concentration of each stored drop is controlled by varying the water activity of a reservoir that is separated from the drops by a thin layer of PDMS through which water, but not the solutes, permeates. The Phase Chip, incorporating a dialysis membrane on-chip, presents several advantages for protein crystallizations. First, protein crystallization is a non-equilibrium process so it makes sense to have dynamic control over the key thermodynamic variable; concentration. The Phase Chip, with its ability to reversibly control protein and precipitant concentrations, renders varying concentration as convenient as varying temperature. Second, by varying the water content of each drop we can explore many different crystallization conditions in the same drop. Finally, we have demonstrated that we can first formulate stable protein solutions, next induce nucleation and then grow large protein crystals. For these reasons, the Phase Chip promises to be a faster, better, and cheaper method for protein crystallization.

  8. A Phase-Variable Surface Layer from the Gut Symbiont Bacteroides thetaiotaomicron.

    Science.gov (United States)

    Taketani, Mao; Donia, Mohamed S; Jacobson, Amy N; Lambris, John D; Fischbach, Michael A

    2015-09-29

    The capsule from Bacteroides, a common gut symbiont, has long been a model system for studying the molecular mechanisms of host-symbiont interactions. The Bacteroides capsule is thought to consist of an array of phase-variable polysaccharides that give rise to subpopulations with distinct cell surface structures. Here, we report the serendipitous discovery of a previously unknown surface structure in Bacteroides thetaiotaomicron: a surface layer composed of a protein of unknown function, BT1927. BT1927, which is expressed in a phase-variable manner by ~1:1,000 cells in a wild-type culture, forms a hexagonally tessellated surface layer. The BT1927-expressing subpopulation is profoundly resistant to complement-mediated killing, due in part to the BT1927-mediated blockade of C3b deposition. Our results show that the Bacteroides surface structure is capable of a far greater degree of structural variation than previously known, and they suggest that structural variation within a Bacteroides species is important for productive gut colonization. Many bacterial species elaborate a capsule, a structure that resides outside the cell wall and mediates microbe-microbe and microbe-host interactions. Species of Bacteroides, the most abundant genus in the human gut, produce a capsule that consists of an array of polysaccharides, some of which are known to mediate interactions with the host immune system. Here, we report the discovery of a previously unknown surface structure in Bacteroides thetaiotaomicron. We show that this protein-based structure is expressed by a subset of cells in a population and protects Bacteroides from killing by complement, a component of the innate immune system. This novel surface layer protein is conserved across many species of the genus Bacteroides, suggesting an important role in colonization and host immune modulation. Copyright © 2015 Taketani et al.

  9. Phase dynamics of high radiance fiber laser arrays with active phase control

    Science.gov (United States)

    Bochove, Erik; Neschke, Brendan; Nair, Niketh; Delgado, Paul; Braiman, Yehuda

    2015-03-01

    The existing model of the LOCSET technique for the active phase synchronization of fiber laser arrays (T. Shay, Opt. Express, 2006) is extended to include relevant physical properties of the system, such as inherent optical path differences (OPD), line-width and group velocity dispersion (GVD), and we also include phase "jitter" of the master oscillator's output in the model, which in experiments is implemented to induce spectral broadening for suppression of nonlinear frequency conversion. Linearization of the phase error signal, which incorrectly predicts convergence to a synchronous equilibrium state, is not performed. Instead, the closed-loop control dynamics are shown to be described by differential equations of Kuramoto type when phase corrector response dynamics are negligible. Linear stability analysis indicates that there is always one and no more than one dynamically stable state. The latter is shown to be normally synchronous, except when strong "jitter" is applied. A Liapounov function is found as subject to the validity of certain symmetry conditions.

  10. Characteristic model based control of the X-34 reusable launch vehicle in its climbing phase

    Institute of Scientific and Technical Information of China (English)

    MENG Bin; WU HongXin; LIN ZongLi; LI Guo

    2009-01-01

    In this paper,a characteristic model based longitudinal control design for the trans-aerosphere vehicle X-34 In its transonic and hypersonic climbing phase is proposed.The design is based on the dynamic characteristics of the vehicle and the curves it is to track in this climbing phase.Through a detailed analysis of the aerodynamics and vehicle dynamics during this climbing phase,an explicit description of the tracking curve for the flight path angle is derived.On the basis of this tracking curve,the tracking curves for the two short-period variables,the angle of attack and the pitch rate,are designed.An all-coefficient adaptive controller is then designed,based on the characteristic modeling,to cause these two short-period variables to follow their respective tracking curves.The proposed design does not require multiple working points,making the design procedure simple.Numerical simulation is performed to validate the performance of the controller.The simulation results Indicate that the resulting control law ensures that the vehicle climbs up successfully under the restrictions on the pitch angle and overloading.

  11. Controlling Chaos of Hybrid Systems by Variable Threshold Values

    Science.gov (United States)

    Ito, Daisuke; Ueta, Tetsushi; Kousaka, Takuji; Imura, Jun'ichi; Aihara, Kazuyuki

    We try to stabilize unstable periodic orbits embedded in a given chaotic hybrid dynamical system by a perturbation of a threshold value. In conventional chaos control methods, a control input is designed by state-feedback, which is proportional to the difference between the target orbit and the current state, and it is applied to a specific system parameter or the state as a small perturbation. During a transition state, the control system consumes a certain control energy given by the integration of such perturbations. In our method, we change the threshold value dynamically to control the chaotic orbit. Unlike the OGY method and the delayed feedback control, no actual control input is added into the system. The state-feedback is utilized only to determine the dynamic threshold value, thus the orbit starting from the current threshold value reaches the next controlled threshold value without any control energy. We obtain the variation of the threshold value from the composite Poincaré map, and the controller is designed by the linear feedback theory with this variation. We demonstrate this method in simple hybrid chaotic systems and show its control performances by evaluating basins of attraction.

  12. Hemispherically in-phase precipitation variability over the last 1700 years in a Madagascar speleothem record

    Science.gov (United States)

    Scroxton, Nick; Burns, Stephen J.; McGee, David; Hardt, Ben; Godfrey, Laurie R.; Ranivoharimanana, Lovasoa; Faina, Peterson

    2017-05-01

    Paleoclimate studies of tropical rainfall have led to a recognition of a predominant pattern of anti-phase behavior between the Northern and Southern hemispheres at both orbital and millennial timescales. Less certain is how regional tropical rainfall patterns have changed in the late Holocene, under boundary conditions and on timescales which are most relevant to the tropics' response to a warming world. Several high-resolution southern hemisphere rainfall records are at odds with meridional movement of the mean Inter-Tropical Convergence Zone location as the major driver of Holocene tropical rainfall variability, with regional precipitation patterns resembling modern day El-Niño Southern Oscillation end members. To test emerging ideas on sub-millennial tropical rainfall variability, additional records from the southern hemisphere are required. We present a new speleothem δ18O record from Anjohibe Cave, northwestern Madagascar, which provides a quasi-annual record of monsoonal strength and precipitation amount for the last 1700 years. The majority of δ18O variability in the record is at the decadal scale, and shows little to no correlation with major climate indices or cyclical climate drivers. At lower frequencies, changes in mean speleothem δ18O show good correlation with other regional precipitation records both north and south of the equator. The regional coherency of tropical rainfall across the west Indian Ocean resembles expansion and contraction of the tropical rain belt and positive-Indian Ocean Dipole-like conditions at different timescales. The cause of this coherency could be related to symmetrical changes in continental sensible heating, or to a low frequency sea surface temperature climate mode.

  13. Backstepping controller of five-level three-phase inverter

    Directory of Open Access Journals (Sweden)

    Majdoul R.

    2014-01-01

    Full Text Available Multilevel converters are becoming increasingly used in many industrial applications due to the many advantages that they offer. The improvements in the output signal quality, lower Total Harmonic Distortion (THD and many other properties make multilevel converters very attractive for connecting photovoltaic generators to medium voltage grid directly or to be used in a local power supply. In this paper, we focus on the implementation of a three-phase five-level diode clamped inverter and design of a performing nonlinear controller using the Backstepping approach. The control objective is to generate, at the system output, sinusoidal three-phase voltages with amplitude and frequency fixed by the reference signal independently of load variations. The performance study of the multilevel inverter and the designed controller are made by simulations in Matlab/Simulink environment.

  14. Regional Heat Sources and the Active and Break Phases of Boreal Summer Intraseasonal Variability

    Energy Technology Data Exchange (ETDEWEB)

    Annamalai, H; Sperber, K R

    2003-12-15

    The boreal summer intraseasonal variability (BSISV) associated with the 30-50 day mode is represented by the co-existence of three components, poleward propagation of convection over the Indian and tropical west Pacific longitudes and eastward propagation along the equator. The hypothesis that the three components influence each other has been investigated using observed OLR, NCEP-NCAR reanalysis, and solutions from an idealized linear model. The null hypothesis is that the three components are mutually independent. Cyclostationary EOF (CsEOF) analysis is applied on filtered OLR to extract the life-cycle of the BSISV. The dominant mode of CsEOF is significantly tied to observed rainfall over the Indian subcontinent. The components of the heating patterns from CsEOF analysis serve as prescribed forcings for the linear model. This allows us to ascertain which heat sources and sinks are instrumental in driving the large-scale monsoon circulation during the BSISV life-cycle. We identify three new findings: (1) the circulation anomalies that develop as a Rossby wave response to suppressed convection over the equatorial Indian Ocean associated with the previous break phase of the BSISV precondition the ocean-atmosphere system in the western Indian Ocean and trigger the next active phase of the BSISV, (2) the development of convection over the tropical west Pacific forces descent anomalies to the west. This, in conjunction with the weakened cross-equatorial flow due to suppressed convective anomalies over the equatorial Indian Ocean reduce the tropospheric moisture over the Arabian Sea, and promote westerly wind anomalies that do not recurve over India. As a result the low-level cyclonic vorticity shifts from India to southeast Asia and break conditions are initiated over India, and (3) the circulation anomalies forced by equatorial Indian Ocean convective anomalies significantly influence the active/break phases over the tropical west Pacific. Our model solutions support

  15. Phase Retrieval for Radio Telescope and Antenna Control

    Science.gov (United States)

    Dean, Bruce

    2011-01-01

    Phase-retrieval is a general term used in optics to describe the estimation of optical imperfections or "aberrations." The purpose of this innovation is to develop the application of phase retrieval to radio telescope and antenna control in the millimeter wave band. Earlier techniques do not approximate the incoherent subtraction process as a coherent propagation. This approximation reduces the noise in the data and allows a straightforward application of conventional phase retrieval techniques for radio telescope and antenna control. The application of iterative-transform phase retrieval to radio telescope and antenna control is made by approximating the incoherent subtraction process as a coherent propagation. Thus, for systems utilizing both positive and negative polarity feeds, this approximation allows both surface and alignment errors to be assessed without the use of additional hardware or laser metrology. Knowledge of the antenna surface profile allows errors to be corrected at a given surface temperature and observing angle. In addition to imperfections of the antenna surface figure, the misalignment of multiple antennas operating in unison can reduce or degrade the signal-to-noise ratio of the received or broadcast signals. This technique also has application to the alignment of antenna array configurations.

  16. Multivariable Control for a Variable Area Turbine Engine

    Science.gov (United States)

    1977-08-01

    high turbine gas flow total temperature after energy loss to seals and dis.s. TT45hi - low turbine gas flow total temperature after energy loss to...vanes and blades. TT451o - low turbine gas flow total temperature after energy loss to seals and discs. TT5 - low turbine gas flow exit total temperature...Proposed advanced gas turbine engine cycles will have many variable geometry components including fan and compressorvane angles, high and low turbine flow

  17. DSP Based Vector Control of Five-Phase Induction Using Fuzzy Logic Control

    Directory of Open Access Journals (Sweden)

    Zakaria Mohamed Salem

    2012-03-01

    Full Text Available Abstract - This paper proposes an indirect field oriented controller for five-phase induction motor drives. The controller is based on fuzzy logic control technique. Simulation is carried out by using the Matlab/Simulink package. A complete control system experimentally implemented using digital signal processing (DSP board. The performance of the proposed system is investigated at different operating conditions. The proposed controller is robust and suitable to high performance five-phase induction motor drives. Simulation and experimental results validate the proposed approaches.

  18. A DSP controlled one-to-three phase matrix converter

    Energy Technology Data Exchange (ETDEWEB)

    Dubovsky, J.; Dobrucly, B; Tabacek, R.; Havrila, R. [Department of Electric Traction and Energetics Faculty of Electrical Engineering, University of Zilina (Slovakia)

    1997-12-31

    This paper deals with the theoretical analysis computer simulation and experimental results of IM fed by a one-to-three phase matrix converter which offers a unique solution for single phase electric traction applications. The proposed drive in comparison with currently used conventional drives reduces the number of power switching elements of the converter, which increases drives dependability and brings lower investment in power electronics used in drive. Further advantage is that the converter is controlled with nearly unity power factor which cuts down the operational expenses and offers higher overall performance of the drive. (orig.) 6 refs.

  19. Design Method of Active Disturbance Rejection Variable Structure Control System

    Directory of Open Access Journals (Sweden)

    Yun-jie Wu

    2015-01-01

    Full Text Available Based on lines cluster approaching theory and inspired by the traditional exponent reaching law method, a new control method, lines cluster approaching mode control (LCAMC method, is designed to improve the parameter simplicity and structure optimization of the control system. The design guidelines and mathematical proofs are also given. To further improve the tracking performance and the inhibition of the white noise, connect the active disturbance rejection control (ADRC method with the LCAMC method and create the extended state observer based lines cluster approaching mode control (ESO-LCAMC method. Taking traditional servo control system as example, two control schemes are constructed and two kinds of comparison are carried out. Computer simulation results show that LCAMC method, having better tracking performance than the traditional sliding mode control (SMC system, makes the servo system track command signal quickly and accurately in spite of the persistent equivalent disturbances and ESO-LCAMC method further reduces the tracking error and filters the white noise added on the system states. Simulation results verify the robust property and comprehensive performance of control schemes.

  20. DISPLACEMENT CONTROL AND KINETIC ANALYSIS OF A NOVEL VARIABLE DISPLACEMENT COMPRESSOR FOR AUTOMOTIVE AIR CONDITIONER

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and inst ead of pneumatic valve the displacement is controlled by electronic control valv e. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed accordin g to the geometrical and kinematical information of the compressor. Using the mo del, the effect of relevant parameters on variable displace control is estimated . It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneu matic valves. And by using this new electronic control device, the optimum syste mic control of AAC is available.

  1. Observer Backstepping Control for Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Galeazzi, Roberto; Gryning, Mikkel Peter Sidoroff; Blanke, Mogens

    2013-01-01

    . The nonlinear controller aims at regulating the generator torque such that an optimal tip-speed ratio can be obtained. Simply relying on the measured rotor angular velocity the proposed observer backstepping controller guarantees global asymptotic tracking of the desired trajectory while maintaining a globally...

  2. LQG Controller Design for Pitch Regulated Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Imran, Raja Muhammed; Hussain, Dil Muhammad Akbar; Chen, Zhe

    2014-01-01

    the effect of disturbance acting on its rotor blades by wind. CART2 (Control Advanced Research Turbine) linear model is produced/generated by FAST (Fatigue, Aerodynamics, Structures and Turbulence) code to test its simulation on MATLAB/Simulink and various results are compared. The designed controller...

  3. Vehicle Thermal Control with a Variable Area Inlet.

    Science.gov (United States)

    1995-12-01

    empirically derived Nusselt number. Proportional, Proportional-Derivative (PD), and Proportional-Integral-Derivative ( PID ) controllers were built and...tested. The PD and PID controllers did not appear to need any gain scheduling for the varying speed and temperature conditions. Lastly, a general design process was detailed. (AN)

  4. Nonlinear variable structure excitation and steam valving controllers for power system stability

    Institute of Scientific and Technical Information of China (English)

    Ben WANG; Zongyuan MAO

    2009-01-01

    A set of novel nonlinear variable structure excitation and steam-valving controllers are proposed in this paper.On the basis of the classical dynamic equations of a generator,excitation control and steam valving control are si-multaneously considered.Design of these controllers combines the differential geometry theory with the variable structure controlling theory.The mathematical model in the form of "an affine nonlinear system" is set up for the control design of a large-scale power plant.The dynamic performance of the nonlinear variable structure controllers proposed for a single ma-chine connected to an infinite bus power system is simulated.Simulation results show that the nonlinear variable structure excitation and steam-valving controllers give satisfactory dynamic performance and good robustness.

  5. Bio-inspired online variable recruitment control of fluidic artificial muscles

    Science.gov (United States)

    Jenkins, Tyler E.; Chapman, Edward M.; Bryant, Matthew

    2016-12-01

    This paper details the creation of a hybrid variable recruitment control scheme for fluidic artificial muscle (FAM) actuators with an emphasis on maximizing system efficiency and switching control performance. Variable recruitment is the process of altering a system’s active number of actuators, allowing operation in distinct force regimes. Previously, FAM variable recruitment was only quantified with offline, manual valve switching; this study addresses the creation and characterization of novel, on-line FAM switching control algorithms. The bio-inspired algorithms are implemented in conjunction with a PID and model-based controller, and applied to a simulated plant model. Variable recruitment transition effects and chatter rejection are explored via a sensitivity analysis, allowing a system designer to weigh tradeoffs in actuator modeling, algorithm choice, and necessary hardware. Variable recruitment is further developed through simulation of a robotic arm tracking a variety of spline position inputs, requiring several levels of actuator recruitment. Switching controller performance is quantified and compared with baseline systems lacking variable recruitment. The work extends current variable recruitment knowledge by creating novel online variable recruitment control schemes, and exploring how online actuator recruitment affects system efficiency and control performance. Key topics associated with implementing a variable recruitment scheme, including the effects of modeling inaccuracies, hardware considerations, and switching transition concerns are also addressed.

  6. Interleaved Boost-Half-Bridge Dual–Input DC-DC Converter with a PWM plus Phase-Shift Control for Fuel Cell Applications

    DEFF Research Database (Denmark)

    Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    This paper presents an isolated dual-input DC-DC converter with a PWM plus phase-shift control for fuel cell hybrid energy systems. The power switches are controlled by phase shifted PWM signals with a variable duty cycle, and thus the two input voltages as well as the output voltage can...

  7. Phase Model with Feedback Control for Power Grids

    CERN Document Server

    Matsuo, Tatsuma

    2013-01-01

    A phase model with feedback control is studied as a dynamical model of power grids. As an example, we study a model network corresponding to the power grid in the Kyushu region. The standard frequency is maintained by the mutual synchronization and the feedback control. Electric failures are induced by an overload. We propose a local feedback method in which the strength of feedback control is proportional to the magnitude of generators. We find that the electric failures do not occur until the utilization ratio is close to 1 under this feedback control. We also find that the temporal response for the time-varying input power is suppressed under this feedback control. We explain the mechanisms using the corresponding global feedback method.

  8. Phase Model with Feedback Control for Power Grids

    Science.gov (United States)

    Matsuo, Tatsuma; Sakaguchi, Hidetsugu

    2013-09-01

    A phase model with feedback control is studied as a dynamical model of power grids. As an example, we study a model network corresponding to the power grid in the Kyushu region. The standard frequency is maintained by the mutual synchronization and the feedback control. Electric failures are induced by an overload. We propose a local feedback method in which the strength of feedback control is proportional to the magnitude of generators. We find that the electric failures do not occur until the utilization ratio is close to 1 under this feedback control. We also find that the temporal response for the time-varying input power is suppressed under this feedback control. We explain the mechanisms using the corresponding global feedback method.

  9. Generic Electronic Board Design to Control 3-Phase Ac

    Directory of Open Access Journals (Sweden)

    RojasMolina A.

    2012-01-01

    Full Text Available This work presents the design and development of a low-cost power manager with controller for a 3-phase AC induction motor, with a wide range of industrial applications. The prototype drive design and development was made using the generic standard on printed board design IPC2221. Power manager consists of two stages. First is control stage, which includes an induction motor control-specific micro-controller. Second is power stage, with IGBTs as switching elements. This design is part of a wider project whose main objective is to advance a methodology to assist the quality improvement of academia-developed electronic prototypes. It is expected that these prototypes will be aligned with industrial standards, facilitating the industry-university connection regarding technological collaboration in the automation and control domain.

  10. Optical Mode Control by Geometric Phase in Quasicrystal Metasurface

    CERN Document Server

    Yulevich, Igor; Shitrit, Nir; Veksler, Dekel; Kleiner, Vladimir; Hasman, Erez

    2015-01-01

    We report on the observation of optical spin-controlled modes from a quasicrystalline metasurface as a result of an aperiodic geometric phase induced by anisotropic subwavelength structure. When geometric phase defects are introduced in the aperiodic structured surface, the modes exhibit polarization helicity dependence resulting in the optical spin-Hall effect. The radiative thermal dispersion bands from a quasicrystal structure were studied where the observed bands arise from the optical spin-orbit interaction induced by the aperiodic space-variant orientations of anisotropic antennas. The optical spin-flip behavior of the revealed modes that arise from the geometric phase pickup was experimentally observed within the visible spectrum by measuring the spin-projected diffraction patterns. The introduced ability to manipulate the light-matter interaction of quasicrystals in a spin-dependent manner provides the route for molding light via spin-optical aperiodic artificial planar surfaces.

  11. Variable-flip-angle single-slab 3D GRASE imaging with phase-independent image reconstruction.

    Science.gov (United States)

    Kim, Hahnsung; Kim, Dong-Hyun; Park, Jaeseok

    2015-03-01

    To develop a single-slab three-dimensional variable-flip-angle gradient- and spin-echo pulse sequence with phase-independent reconstruction that is highly energy- or encoding-efficient for high resolution isotropic imaging at high magnetic field. Amplitude modulation in the proposed pulse sequence was alleviated using a variable-flip-angle induced smooth signal evolution along the long echo train. To avoid phase modulation, instead of directly interleaving phase encoding signals with different off-resonance induced phase accumulation over multiple echoes, phase-independent image reconstruction was performed, wherein each echo image was separately reconstructed using convolution-interpolation with echo-interleaving self-calibration and then combined. Numerical and experimental studies were performed at 3.0 T for generation of clinical T2 -weighted contrast to investigate the effectiveness of the proposed method over existing methods. Compared with conventional techniques, the proposed method produces smooth amplitude variation, no ghosting artifacts (no phase modulation), and competitive signal-to-noise ratio. An energy-efficient variable-flip-angle gradient- and spin-echo reduces specific absorption rate by 71% without significant loss of signal-to-noise ratio, while an encoding-efficient one decreases imaging time by 54% with a slight loss of signal-to-noise ratio. We successfully demonstrated that the proposed variable-flip-angle gradient- and spin-echo can be a highly promising energy- or encoding-efficient alternative for high resolution isotropic imaging. © 2014 Wiley Periodicals, Inc.

  12. The Control System Simulation of Variable-Speed Constant-Frequency Wind Turbine

    Institute of Scientific and Technical Information of China (English)

    窦金延; 曹娜

    2010-01-01

    <正>In general,Variable-Speed Constant Frequency (VSCF)Wind generation system is controlled by stator voltage orientation method which based on the mathematic model of VSCF Wind generation system and discussed the control strategy.Present the whole dynamic control model of variable-speed wind generator system in MATLAB/ Simulink,and the simulation results confirm the validity and effectiveness of the proposed control strategy.

  13. Stabilizing Gain Selection of Networked Variable Gain Controller to Maximize Robustness Using Particle Swarm Optimization

    CERN Document Server

    Pan, Indranil; Ghosh, Soumyajit; Gupta, Amitava; 10.1109/PACC.2011.5978958

    2012-01-01

    Networked Control Systems (NCSs) are often associated with problems like random data losses which might lead to system instability. This paper proposes a method based on the use of variable controller gains to achieve maximum parametric robustness of the plant controlled over a network. Stability using variable controller gains under data loss conditions is analyzed using a suitable Linear Matrix Inequality (LMI) formulation. Also, a Particle Swarm Optimization (PSO) based technique is used to maximize parametric robustness of the plant.

  14. A Position Sensorless Control Method for SRM Based on Variation of Phase Inductance

    Science.gov (United States)

    Komatsuzaki, Akitomo; Miki, Ichiro

    Switched reluctance motor (SRM) drives are suitable for variable speed industrial applications because of the simple structure and high-speed capability. However, it is necessary to detect the rotor position with a position sensor attached to the motor shaft. The use of the sensor increases the cost of the drive system and machine size, and furthermore the reliability of the system is reduced. Therefore, several approaches to eliminate the position sensor have already been reported. In this paper, a position sensorless control method based on the variation of the phase inductance is described. The phase inductance regularly varies with the rotor position. The SRM is controlled without the position sensor using the de-fluxing period and the phase inductance. The turn-off timing is determined by computing the difference of angle between the sampling point and the aligned point and the variation of angle during the de-fluxing period. In the magnetic saturation region, the phase inductance at the current when the effect of the saturation starts is computed and the sensorless control can be carried out using this inductance. Experimental results show that the SRM is well controlled without the position sensor using the proposed method.

  15. Output-Based Control of Robots with Variable Stiffness Actuation

    Directory of Open Access Journals (Sweden)

    Gianluca Palli

    2011-01-01

    Full Text Available The output-based control of a redundant robotic manipulator with relevant and adjustable joint stiffness is addressed. The proposed controller is configured as a cascade system that allows the decoupling of the actuators dynamics from the arm dynamics and the consequent reduction of the order of the manipulator dynamic model. Moreover, the proposed controller does not require the knowledge of the whole robot state: only the positions of the actuators and of the joints are necessary. This approach represents a significant simplification with respect to previously proposed state feedback techniques. The problem of controlling simultaneously the position trajectory and the desired stiffness in both the joint and work space is investigated, and the relations between the manipulator redundancy and the selection of both the joint and work space stiffness of the manipulator are discussed. The effectiveness of the proposed approach is verified by simulations of a 3 degrees of freedom planar manipulator.

  16. Range of control of cardiovascular variables by the hypothalamus

    Science.gov (United States)

    Smith, O. A.; Stephenson, R. B.; Randall, D. C.

    1974-01-01

    New methodologies were utilized to study the influence of the hypothalamus on the cardiovascular system. The regulation of myocardial activity was investigated in monkeys with hypothalamic lesions that eliminate cardiovascular responses. Observations showed that a specific part of the hypothalamus regulates changes in myocardial contractility that accompanies emotion. Studies of the hypothalamus control of renal blood flow showed the powerful potential control of this organ over renal circulation.

  17. Towards a FPGA-controlled deep phase modulation interferometer

    CERN Document Server

    Terán, M; Gesa, L l; Mateos, I; Gibert, F; Karnesis, N; Ramos-Castro, J; Schwarze, T S; Gerberding, O; Heinzel, G; Guzmán, F; Nofrarias, M

    2014-01-01

    Deep phase modulation interferometry was proposed as a method to enhance homodyne interferometers to work over many fringes. In this scheme, a sinusoidal phase modulation is applied in one arm while the demodulation takes place as a post-processing step. In this contribution we report on the development to implement this scheme in a fiber coupled interferometer controlled by means of a FPGA, which includes a LEON3 soft-core processor. The latter acts as a CPU and executes a custom made application to communicate with a host PC. In contrast to usual FPGA-based designs, this implementation allows a real-time fine tuning of the parameters involved in the setup, from the control to the post-processing parameters.

  18. Phase modulated solitary waves controlled by bottom boundary condition

    CERN Document Server

    Mukherjee, Abhik

    2014-01-01

    A forced KdV equation is derived to describe weakly nonlinear, shallow water surface wave propagation over non trivial bottom boundary condition. We show that different functional forms of bottom boundary conditions self-consistently produce different forced kdV equations as the evolution equations for the free surface. Solitary wave solutions have been analytically obtained where phase gets modulated controlled by bottom boundary condition whereas amplitude remains constant.

  19. Command and Control for Multifunction Phased Array Radar

    OpenAIRE

    Weber, Mark E.; Cho, John Y. N.; Thomas, Henry G

    2017-01-01

    We discuss the challenge of managing the Multifunction Phased Array Radar (MPAR) timeline to satisfy the requirements of its multiple missions, with a particular focus on weather surveillance. This command and control (C2) function partitions the available scan time among these missions, exploits opportunities to service multiple missions simultaneously, and utilizes techniques for increasing scan rate where feasible. After reviewing the candidate MPAR architectures and relevant previous rese...

  20. Control of variable speed wind turbine with doubly-fed induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Soerensen, P. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Iov, F.; Blaabjerg, F. [Aalborg Univ., Inst. of Energy Technology, Aalborg (Denmark)

    2004-07-01

    draIn this paper, a Control method suitable for a variable speed grid connected pitch-controlled wind turbine with doubly-fed induction generator (DFIG) is developed. The targets of the Control system are: 1) to Control the power drawn from the wind turbine in order to track the wind turbine optimum operation point 2) to limit the power in case of high wind speeds and 3) to Control the reactive power interchanged between the wind turbine generator and the grid. The considered configuration of DFIG is an induction generator with a wound rotor connected to the grid through a back-to-back power converter and a stator directly connected to the grid. The paper presents the overall Control system of the variable speed DFIG wind turbine, with focus on the Control strategies and algorithms applied at each hierarchical Control level of the wind turbine. There are two Control levels: a DFIG Control level and wind turbine Control level. The DFIG Control level contains a fast Control of the power converter and of the doubly-fed induction generator and it has as goal to Control the active and reactive power of the wind turbine independently. The wind turbine Control level supervises with Control signals both the DFIG Control level and the hydraulic pitch Control system of the wind turbine. The present Control method is designed for normal continuous operations. The variable speed/variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT, which makes possible to investigate the dynamic performance of gid-connected wind turbines as a part of realistic electrical grid models. Several significant simulation results are performed With the overall Control-implemented algorithm applied on a variable speed, variable pitch wind turbine model. (au)

  1. Distribution and variability of redox zones controlling spatial variability of arsenic in the Mississippi River Valley alluvial aquifer, southeastern Arkansas

    Science.gov (United States)

    Sharif, M.U.; Davis, R.K.; Steele, K.F.; Kim, B.; Hays, P.D.; Kresse, T.M.; Fazio, J.A.

    2008-01-01

    . Spatial variability of gypsum solubility and simultaneous SO42- reduction with co-precipitation of As and sulfide is an important limiting process controlling the concentration of As in groundwater in the area. ?? 2008 Elsevier B.V. All rights reserved.

  2. Circumstellar Dust Composition of M-type Mira Variables observed with phase with Spitzer

    Science.gov (United States)

    Güth, Tina; Creech-Eakman, Michelle J.

    2017-01-01

    Our research concerns the detailed dust composition surrounding Mira variables. These regular pulsators are easily observed in the optical and infrared due to their changes in brightness. Data on 25 galactic Miras were obtained with the Spitzer Infrared Spectrograph (IRS) instrument in 2008-09 under a GO program led by Creech-Eakman. The stars were observed approximately once per month to track changes in their brightness and spectral features. This dataset is unique for both the number of observations of each star and the high SNR due to their intrinsic brightness.The stars in this study span the range of oxygen- to carbon-rich, with each type exhibiting certain known solid state components (i.e dust). The current focus is on trying to reproduce dust spectral features in the short, high (SH) and long, high (LH) resolution wavelength range (~9.7 - 40 microns) of the oxygen-rich Miras (C/O features that provide insight into the stellar atmospheres and circumstellar dust composition with phase.Using the 1-D radiative transfer modeling code, DUSTY, we are attempting to identify several broad, and some sharp, dust features by including recently derived laboratory spectral indices for dust opacities. Prominent features seen in oxygen-rich Mira variables include potential identifications of water ice emission, as well as amorphous and crystalline silicates. We implement a greybody continuum obtained from MARCS, a 1-D hydrostatic spherical LTE model grid code, as the stellar continuum input for DUSTY. Using a greybody rather than a blackbody curve allows us to obtain a better agreement between the DUSTY spectrum and the Spitzer data. We will show these amended model fits that will improve the identification of the dust and other features in the spectra.

  3. Guaranteeing Isochronous Control of Networked Motion Control Systems Using Phase Offset Adjustment

    Directory of Open Access Journals (Sweden)

    Ikhwan Kim

    2015-06-01

    Full Text Available Guaranteeing isochronous transfer of control commands is an essential function for networked motion control systems. The adoption of real-time Ethernet (RTE technologies may be profitable in guaranteeing deterministic transfer of control messages. However, unpredictable behavior of software in the motion controller often results in unexpectedly large deviation in control message transmission intervals, and thus leads to imprecise motion. This paper presents a simple and efficient heuristic to guarantee the end-to-end isochronous control with very small jitter. The key idea of our approach is to adjust the phase offset of control message transmission time in the motion controller by investigating the behavior of motion control task. In realizing the idea, we performed a pre-runtime analysis to determine a safe and reliable phase offset and applied the phase offset to the runtime code of motion controller by customizing an open-source based integrated development environment (IDE. We also constructed an EtherCAT-based motion control system testbed and performed extensive experiments on the testbed to verify the effectiveness of our approach. The experimental results show that our heuristic is highly effective even for low-end embedded controller implemented in open-source software components under various configurations of control period and the number of motor drives.

  4. Robustification and Optimization in Repetitive Control For Minimum Phase and Non-Minimum Phase Systems

    Science.gov (United States)

    Prasitmeeboon, Pitcha

    Repetitive control (RC) is a control method that specifically aims to converge to zero tracking error of a control systems that execute a periodic command or have periodic disturbances of known period. It uses the error of one period back to adjust the command in the present period. In theory, RC can completely eliminate periodic disturbance effects. RC has applications in many fields such as high-precision manufacturing in robotics, computer disk drives, and active vibration isolation in spacecraft. The first topic treated in this dissertation develops several simple RC design methods that are somewhat analogous to PID controller design in classical control. From the early days of digital control, emulation methods were developed based on a Forward Rule, a Backward Rule, Tustin's Formula, a modification using prewarping, and a pole-zero mapping method. These allowed one to convert a candidate controller design to discrete time in a simple way. We investigate to what extent they can be used to simplify RC design. A particular design is developed from modification of the pole-zero mapping rules, which is simple and sheds light on the robustness of repetitive control designs. RC convergence requires less than 90 degree model phase error at all frequencies up to Nyquist. A zero-phase cutoff filter is normally used to robustify to high frequency model error when this limit is exceeded. The result is stabilization at the expense of failure to cancel errors above the cutoff. The second topic investigates a series of methods to use data to make real time updates of the frequency response model, allowing one to increase or eliminate the frequency cutoff. These include the use of a moving window employing a recursive discrete Fourier transform (DFT), and use of a real time projection algorithm from adaptive control for each frequency. The results can be used directly to make repetitive control corrections that cancel each error frequency, or they can be used to update a

  5. Bicellar mixture phase behavior examined by variable-pressure deuterium NMR and ambient pressure DSC.

    Science.gov (United States)

    Uddin, Md Nasir; Morrow, Michael R

    2010-07-20

    Variable-pressure deuterium nuclear magnetic resonance ((2)H NMR) has been used to study the pressure-temperature phase diagram of bicellar mixtures containing 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC). Spectra were obtained for DMPC-d(54)/DHPC (3:1), DMPC-d(54)/DHPC (4.4:1), DMPC/DHPC-d(22) (3:1), and DMPC/DHPC-d(22) (4.4:1) in the range 10-68 degrees C at ambient pressure, 66 MPa, 102 MPa, and 135 MPa. Isotropic-to-nematic and nematic-to-lamellar transition temperatures were found to rise with pressure at approximately 0.15 and approximately 0.14 degrees C/MPa, respectively, for DMPC-d(54)/DHPC (3:1) and at at approximately 0.19 and approximately 0.18 degrees C/MPa, respectively, for DMPC-d(54)/DHPC (4.4:1). Pressure had little effect on the range of DMPC-d(54) chain orientational order through the nematic phase temperature range, but the behavior of chain orientational order at the nematic-to-lamellar transition was found to vary slightly with pressure. Comparison of differential scanning calorimetry (DSC) observations with ambient-pressure (2)H NMR observations of DMPC-d(54) in the bicellar mixtures suggests that absorption of heat persists for a few degrees above the onset of axially symmetric DMPC-d(54) reorientation.

  6. Active control of the spatial MRI phase distribution with optimal control theory

    Science.gov (United States)

    Lefebvre, Pauline M.; Van Reeth, Eric; Ratiney, Hélène; Beuf, Olivier; Brusseau, Elisabeth; Lambert, Simon A.; Glaser, Steffen J.; Sugny, Dominique; Grenier, Denis; Tse Ve Koon, Kevin

    2017-08-01

    This paper investigates the use of Optimal Control (OC) theory to design Radio-Frequency (RF) pulses that actively control the spatial distribution of the MRI magnetization phase. The RF pulses are generated through the application of the Pontryagin Maximum Principle and optimized so that the resulting transverse magnetization reproduces various non-trivial and spatial phase patterns. Two different phase patterns are defined and the resulting optimal pulses are tested both numerically with the ODIN MRI simulator and experimentally with an agar gel phantom on a 4.7 T small-animal MR scanner. Phase images obtained in simulations and experiments are both consistent with the defined phase patterns. A practical application of phase control with OC-designed pulses is also presented, with the generation of RF pulses adapted for a Magnetic Resonance Elastography experiment. This study demonstrates the possibility to use OC-designed RF pulses to encode information in the magnetization phase and could have applications in MRI sequences using phase images.

  7. Self-Tuning of Design Variables for Generalized Predictive Control

    Science.gov (United States)

    Lin, Chaung; Juang, Jer-Nan

    2000-01-01

    Three techniques are introduced to determine the order and control weighting for the design of a generalized predictive controller. These techniques are based on the application of fuzzy logic, genetic algorithms, and simulated annealing to conduct an optimal search on specific performance indexes or objective functions. Fuzzy logic is found to be feasible for real-time and on-line implementation due to its smooth and quick convergence. On the other hand, genetic algorithms and simulated annealing are applicable for initial estimation of the model order and control weighting, and final fine-tuning within a small region of the solution space, Several numerical simulations for a multiple-input and multiple-output system are given to illustrate the techniques developed in this paper.

  8. Advanced nonlinear control of three phase series active power filter

    Directory of Open Access Journals (Sweden)

    Abouelmahjoub Y.

    2014-01-01

    Full Text Available The problem of controlling three-phase series active power filter (TPSAPF is addressed in this paper in presence of the perturbations in the voltages of the electrical supply network. The control objective of the TPSAPF is twofold: (i compensation of all voltage perturbations (voltage harmonics, voltage unbalance and voltage sags, (ii regulation of the DC bus voltage of the inverter. A controller formed by two nonlinear regulators is designed, using the Backstepping technique, to provide the above compensation. The regulation of the DC bus voltage of the inverter is ensured by the use of a diode bridge rectifier which its output is in parallel with the DC bus capacitor. The Analysis of controller performances is illustrated by numerical simulation in Matlab/Simulink environment.

  9. A Fuzzy-Logic-Based Controller for Three-Phase PWM Rectifier With Unity Power Factor Operation

    Directory of Open Access Journals (Sweden)

    A. Bouafia

    2008-03-01

    Full Text Available In this paper, direct power control (DPC of three-phase PWM rectifiers based on fuzzy logic controller is presented, without line voltage sensors. The control technique is built upon the ideas of the well known direct torque control (DTC for induction motors. 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 proposed fuzzy logic controller presents the advantage to be based on linguistic description and does not require a mathematical model of the system. The controller ensures a good regulation of the output voltage, and guarantees the power factor close to one. The simulation results show that the designed fuzzy controller has a good dynamic behavior, a good rejection of impact load disturbance, and is very robust.

  10. Solar powered actuator with continuously variable auxiliary power control

    Science.gov (United States)

    Nola, F. J. (Inventor)

    1984-01-01

    A solar powered system is disclosed in which a load such as a compressor is driven by a main induction motor powered by a solar array. An auxiliary motor shares the load with the solar powered motor in proportion to the amount of sunlight available, is provided with a power factor controller for controlling voltage applied to the auxiliary motor in accordance with the loading on that motor. In one embodiment, when sufficient power is available from the solar cell, the auxiliary motor is driven as a generator by excess power from the main motor so as to return electrical energy to the power company utility lines.

  11. THERMAL PROCESSING OF AGARICUS BISPORUS AND ITS CONTROL VARIABLES

    OpenAIRE

    Salas de la Torre, N.; Bazán, D.; Osorio, A.; Cornejo, O.; Reyna, L.; García Pantigozo, M.; Carhuaneho, H.

    2014-01-01

    The main objective of this work to estab1ish the controlled use of heat as a function of the pH in order to destroy all the microorganisms that are this bacterias anaerobic forced thermopiles and essentially mesófilas. The bacteria more resistant esporulada to 1he heat is Clostridium botulinum and it is considered lndicative microorganísm of the sterellization. Another parameter of very important control is the quality of the matter it prevails that it can resist the operations of thermal prc...

  12. DESINGING OF ANN BASED SPEED CONTROLLER FOR PHASE CONTROLLED DC MOTOR

    Directory of Open Access Journals (Sweden)

    MR. M.V.SUDARSAN

    2011-07-01

    Full Text Available For electrical drives good dynamic performance is mandatory so as to respond to the changes in command speed and torques, so various speed control techniques are being used for real time applications. The speed of a dc motor can be controlled using various controllers like PI- Controller, Artificial Neural Network (ANNcontroller. ANN theory is recently getting increasing emphasis in process control applications. The paper describes application of ANN in a speed control system that uses a phase-controlled bridge converter and aseparately excited DC machine. The ANN controller for current and speed loops are implemented in MATLAB/SIMULINK, replacing the conventional Proportional-Integral (PI control method. The simulationstudy indicates the superiority of artificial neural network control over the conventional control methods. This control seems to have a lot of promise in the applications of power electronics.

  13. Control and Simulation of Continuously Variable Transmission for Electric Transmission System

    Institute of Scientific and Technical Information of China (English)

    张豫南; 葛蕴珊; 马晓军; 臧克茂

    2004-01-01

    According to the study of electric transmission, the concept of the fore and the aft power chain is presented. The control method of continuously variable transmission is established in the aft chain of electric transmission based on brushless DC motor. A fuzzy controller is designed with continuous fuzzy variables and the simulation module of the aft power chain is proved by test. The fuzzy controller controls the process of continuously variable transmission steadily and the acceleration of vehicle is quick according to simulation results. The elementary performance exhibited in the simulation is a foundation for the further study of the electric transmission track vehicle.

  14. Control of variable speed wind turbines with doubly-fed induction generators

    DEFF Research Database (Denmark)

    Hansen, A. D.; Soerensen, Poul; Iov, Florin;

    2004-01-01

    The paper presents an overall control method for variable speed pitch controlled wind turbines with double-feed induction generators (DFIG). Emphasis is on control strategies and algorithms applied at each hierarchical control level of the wind turbine. The objectives of the control system are: 1......) to control the power drawn from the wind turbine in order to track the wind turbine maximum power operation point, 2) to limit the power in case of large wind speeds, and 3) to control the reactive power interchanged between the wind turbine generator and the grid. The present control method is designed...... for normal continuous operations. The strongest feature of the implemented control method is that it allows the turbine to operate with the optimum power efficiency over a wider range of wind speeds. The model of the variable speed, variable pitch wind turbine with doubly-fed induction generator...

  15. Fixed-node and fixed-phase approximations and their relationship to variable spins in quantum Monte Carlo

    CERN Document Server

    Melton, Cody A

    2016-01-01

    We compare the fixed-phase approximation with the better known, but closely related fixed-node approximation on several testing examples. We found that both approximations behave very similarly with the fixed-phase results being very close to the fixed-node method whenever nodes/phase were of high and comparable accuracy. The fixed-phase exhibited larger biases when the trial wave functions errors in the nodes/phase were intentionally driven to unrealistically large values. We also present a formalism that enables to describe wave functions with the full antisymmetry in spin-spatial degrees of freedom using our recently developed method for systems with spins as fully quantum variables. This opens new possibilities for simulations of fermionic systems in the fixed-phase approximation formalism.

  16. Required response time for variable air volume fume hood controllers.

    Science.gov (United States)

    Ekberg, L E; Melin, J

    2000-03-01

    This paper describes results from tests made with the aim of investigating how quickly the exhaust air flow rate through fume hoods needs to be controlled in order to prevent contaminants from leaking out of the fume hood and putting the safety of the laboratory personnel at risk. The measurements were made on a laboratory fume hood in a chemical laboratory. There were no other fume hoods in the laboratory, and the measurements were made without interference from persons entering or leaving the laboratory or walking about in it. A tracer gas method was used with the concentration of dinitrogen oxide (N(2)O) being recorded by a Foxboro Miran 101 infra-red gas analyser. In parallel with the tracer gas measurements, the air velocity through the face opening was also measured, as was the control signal to the damper controlling the air flow rate. The measurements show an increased outward leakage of tracer gas from the fume hood if the air flow rate is not re-established within 1-2 s after the sash is opened. If the delay exceeds 3 s the safety function is temporarily defeated. The measurements were made under virtually ideal conditions. Under more typical conditions, the fume hood could be exposed to various other external perturbations, which means that the control system should re-establish the correct exhaust flow more quickly than indicated by the measurement results obtained under these almost ideal conditions.

  17. A Capillary-Based Static Phase Separator for Highly Variable Wetting Conditions

    Science.gov (United States)

    Thomas, Evan A.; Graf, John C.; Weislogel, Mark M.

    2010-01-01

    The invention, a static phase separator (SPS), uses airflow and capillary wetting characteristics to passively separate a two-phase (liquid and air) flow. The device accommodates highly variable liquid wetting characteristics. The resultant design allows for a range of wetting properties from about 0 to over 90 advancing contact angle, with frequent complete separation of liquid from gas observed when using appropriately scaled test conditions. Additionally, the design accommodates a range of air-to-liquid flow-rate ratios from only liquid flow to over 200:1 air-to-liquid flow rate. The SPS uses a helix input section with an ice-cream-cone-shaped constant area cross section (see figure). The wedge portion of the cross section is on the outer edge of the helix, and collects the liquid via centripetal acceleration. The helix then passes into an increasing cross-sectional area vane region. The liquid in the helix wedge is directed into the top of capillary wedges in the liquid containment section. The transition from diffuser to containment section includes a 90 change in capillary pumping direction, while maintaining inertial direction. This serves to impinge the liquid into the two off-center symmetrical vanes by the airflow. Rather than the airflow serving to shear liquid away from the capillary vanes, the design allows for further penetration of the liquid into the vanes by the air shear. This is also assisted by locating the air exit ports downstream of the liquid drain port. Additionally, any droplets not contained in the capillary vanes are re-entrained downstream by a third opposing capillary vane, which directs liquid back toward the liquid drain port. Finally, the dual air exit ports serve to slow the airflow down, and to reduce the likelihood of shear. The ports are stove-piped into the cavity to form an unfriendly capillary surface for a wetting fluid to carryover. The liquid drain port is located at the start of the containment region, allowing for

  18. Control strategy for energy-efficient bipedal walking with variable leg stiffness

    NARCIS (Netherlands)

    Visser, L.C.; Stramigioli, Stefano; Carloni, Raffaella

    In this work, we propose a hybrid model for a bipedal walker with controlled variable leg stiffness, and a control strategy for stable gait control. The control reference is a passive gait of the limit-case bipedal spring-loaded inverted pendulum model with massless feet, ensuring that the gait is

  19. Control strategy for energy-efficient bipedal walking with variable leg stiffness

    NARCIS (Netherlands)

    Visser, L.C.; Stramigioli, S.; Carloni, R.

    2013-01-01

    In this work, we propose a hybrid model for a bipedal walker with controlled variable leg stiffness, and a control strategy for stable gait control. The control reference is a passive gait of the limit-case bipedal spring-loaded inverted pendulum model with massless feet, ensuring that the gait is c

  20. A long-lasting quiescence phase of the eruptive variable V1118 Ori

    CERN Document Server

    Lorenzetti, D; Giannini, T; Harutyunyan, A; Arkharov, A A; Larionov, V M; Cusano, F; Di Paola, A; Causi, G Li; Nisini, B; Speziali, R; Vitali, F

    2015-01-01

    V1118 Ori is an eruptive variable belonging to the EXor class of Pre-Main Sequence stars whose episodic outbursts are attributed to disk accretion events. Since 2006, V1118 Ori is in the longest quiescence stage ever observed between two subsequent outbursts of its recent history. We present near-infrared photometry of V1118 Ori carried out during the last eight years, along with a complete spectroscopic coverage from 0.35 to 2.5 um. A longterm sampling of V1118 Ori in quiescence has never been done, hence we can benefit from the current circumstance to determine the lowest values (i.e. the zeroes) of the parameters to be used as a reference for evaluating the physical changes typical of more active phases. A quiescence mass accretion rate between 1--3 $\\times$ 10$^{-9}$ M$_{\\sun}$ yr$^{-1}$ can be derived and the difference with previous determinations is discussed. From line emission and IR colors analysis a visual extinction of 1-2 mag is consistently derived, confirming that V1118 Ori (at least in quiesce...

  1. Variable Displacement Control of the Concrete Pumping System Based on Dynamic Programming

    Directory of Open Access Journals (Sweden)

    Ye Min

    2017-01-01

    Full Text Available To solve the problems of cylinder piston striking cylinder and the hydraulic shocking of the main pump, and causing energy waste problem, the method of variable displacement control of piston stroke was proposed. In order to achieve effective control of the piston stroke, variable displacement control model was established under the physical constraint condition of non-collision between piston and cylinder. And the control process was realized by Dynamic Programming(DP, the simulation and test results show that piston of concrete pumping system don’t strike cylinder and reduce the hydraulic shock of the main pump outlet, meanwhile improve the response speed of the cylinder and achieve energy-saving purposes under varying loads. This control model built in the integration design space of structure variable and control variable is of guiding significance for solving open-loop system’s engineering problems.

  2. Perceptions of control and unrealistic optimism in early-phase cancer trials.

    Science.gov (United States)

    Jansen, Lynn A; Mahadevan, Daruka; Appelbaum, Paul S; Klein, William M P; Weinstein, Neil D; Mori, Motomi; Degnin, Catherine; Sulmasy, Daniel P

    2017-08-03

    Recent research has found unrealistic optimism (UO) among patient-subjects in early-phase oncology trials. Our aim was to investigate the cognitive and motivational factors that evoke this bias in this context. We expected perceptions of control to be a strong correlate of unrealistic optimism. A study of patient-subjects enrolled in early-phase oncology trials was conducted at two sites in the USA. Respondents completed questionnaires designed to assess unrealistic optimism and several risk attribute variables that have been found to evoke the bias in other contexts. One hundred and seventy-one patient-subjects agreed to be interviewed for our study. Significant levels of perceived controllability were found with respect to all nine research-related questions. Perceptions of control were found to predict unrealistic optimism. Two other risk attribute variables, awareness of indicators (p=0.024) and mental image (p=0.022), were correlated with unrealistic optimism. However, in multivariate regression analysis, awareness and mental image dropped out of the model and perceived controllability was the only factor independently associated with unrealistic optimism (poptimism about benefiting personally from trial participation. Effective interventions to counteract unrealistic optimism may need to address the psychological factors that give rise to distorted risk/benefit processing. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  3. Geomorphological control on variably saturated hillslope hydrology and slope instability

    Science.gov (United States)

    Giuseppe, Formetta; Simoni, Silvia; Godt, Jonathan W.; Lu, Ning; Rigon, Riccardo

    2016-01-01

    In steep topography, the processes governing variably saturated subsurface hydrologic response and the interparticle stresses leading to shallow landslide initiation are physically linked. However, these processes are usually analyzed separately. Here, we take a combined approach, simultaneously analyzing the influence of topography on both hillslope hydrology and the effective stress fields within the hillslope itself. Clearly, runoff and saturated groundwater flow are dominated by gravity and, ultimately, by topography. Less clear is how landscape morphology influences flows in the vadose zone, where transient fluxes are usually taken to be vertical. We aim to assess and quantify the impact of topography on both saturated and unsaturated hillslope hydrology and its effects on shallow slope stability. Three real hillslope morphologies (concave, convex, and planar) are analyzed using a 3-D, physically based, distributed model coupled with a module for computation of the probability of failure, based on the infinite slope assumption. The results of the analyses, which included parameter uncertainty analysis of the results themselves, show that convex and planar slopes are more stable than concave slopes. Specifically, under the same initial, boundary, and infiltration conditions, the percentage of unstable areas ranges from 1.3% for the planar hillslope, 21% for convex, to a maximum value of 33% for the concave morphology. The results are supported by a sensitivity analysis carried out to examine the effect of initial conditions and rainfall intensity.

  4. Geomorphological control on variably saturated hillslope hydrology and slope instability

    Science.gov (United States)

    Giuseppe, Formetta; Simoni, Silvia; Godt, Jonathan W.; Lu, Ning; Rigon, Riccardo

    2016-06-01

    In steep topography, the processes governing variably saturated subsurface hydrologic response and the interparticle stresses leading to shallow landslide initiation are physically linked. However, these processes are usually analyzed separately. Here, we take a combined approach, simultaneously analyzing the influence of topography on both hillslope hydrology and the effective stress fields within the hillslope itself. Clearly, runoff and saturated groundwater flow are dominated by gravity and, ultimately, by topography. Less clear is how landscape morphology influences flows in the vadose zone, where transient fluxes are usually taken to be vertical. We aim to assess and quantify the impact of topography on both saturated and unsaturated hillslope hydrology and its effects on shallow slope stability. Three real hillslope morphologies (concave, convex, and planar) are analyzed using a 3-D, physically based, distributed model coupled with a module for computation of the probability of failure, based on the infinite slope assumption. The results of the analyses, which included parameter uncertainty analysis of the results themselves, show that convex and planar slopes are more stable than concave slopes. Specifically, under the same initial, boundary, and infiltration conditions, the percentage of unstable areas ranges from 1.3% for the planar hillslope, 21% for convex, to a maximum value of 33% for the concave morphology. The results are supported by a sensitivity analysis carried out to examine the effect of initial conditions and rainfall intensity.

  5. Lyapunov exponents and phase diagrams reveal multi-factorial control over TRAIL-induced apoptosis

    Science.gov (United States)

    Aldridge, Bree B; Gaudet, Suzanne; Lauffenburger, Douglas A; Sorger, Peter K

    2011-01-01

    Receptor-mediated apoptosis proceeds via two pathways: one requiring only a cascade of initiator and effector caspases (type I behavior) and the second requiring an initiator–effector caspase cascade and mitochondrial outer membrane permeabilization (type II behavior). Here, we investigate factors controlling type I versus II phenotypes by performing Lyapunov exponent analysis of an ODE-based model of cell death. The resulting phase diagrams predict that the ratio of XIAP to pro-caspase-3 concentrations plays a key regulatory role: type I behavior predominates when the ratio is low and type II behavior when the ratio is high. Cell-to-cell variability in phenotype is observed when the ratio is close to the type I versus II boundary. By positioning multiple tumor cell lines on the phase diagram we confirm these predictions. We also extend phase space analysis to mutations affecting the rate of caspase-3 ubiquitylation by XIAP, predicting and showing that such mutations abolish all-or-none control over activation of effector caspases. Thus, phase diagrams derived from Lyapunov exponent analysis represent a means to study multi-factorial control over a complex biochemical pathway. PMID:22108795

  6. Lyapunov exponents and phase diagrams reveal multi-factorial control over TRAIL-induced apoptosis.

    Science.gov (United States)

    Aldridge, Bree B; Gaudet, Suzanne; Lauffenburger, Douglas A; Sorger, Peter K

    2011-11-22

    Receptor-mediated apoptosis proceeds via two pathways: one requiring only a cascade of initiator and effector caspases (type I behavior) and the second requiring an initiator-effector caspase cascade and mitochondrial outer membrane permeabilization (type II behavior). Here, we investigate factors controlling type I versus II phenotypes by performing Lyapunov exponent analysis of an ODE-based model of cell death. The resulting phase diagrams predict that the ratio of XIAP to pro-caspase-3 concentrations plays a key regulatory role: type I behavior predominates when the ratio is low and type II behavior when the ratio is high. Cell-to-cell variability in phenotype is observed when the ratio is close to the type I versus II boundary. By positioning multiple tumor cell lines on the phase diagram we confirm these predictions. We also extend phase space analysis to mutations affecting the rate of caspase-3 ubiquitylation by XIAP, predicting and showing that such mutations abolish all-or-none control over activation of effector caspases. Thus, phase diagrams derived from Lyapunov exponent analysis represent a means to study multi-factorial control over a complex biochemical pathway.

  7. Phase-controlled coherent population trapping in superconducting quantum circuits

    Institute of Scientific and Technical Information of China (English)

    程广玲; 王一平; 陈爱喜

    2015-01-01

    We investigate the influences of the-applied-field phases and amplitudes on the coherent population trapping behavior in superconducting quantum circuits. Based on the interactions of the microwave fields with a single∆-type three-level fluxonium qubit, the coherent population trapping could be obtainable and it is very sensitive to the relative phase and amplitudes of the applied fields. When the relative phase is tuned to 0 orπ, the maximal atomic coherence is present and coherent population trapping occurs. While for the choice ofπ/2, the atomic coherence becomes weak. Meanwhile, for the fixed relative phaseπ/2, the value of coherence would decrease with the increase of Rabi frequency of the external field coupled with two lower levels. The responsible physical mechanism is quantum interference induced by the control fields, which is indicated in the dressed-state representation. The microwave coherent phenomenon is present in our scheme, which will have potential applications in optical communication and nonlinear optics in solid-state devices.

  8. Crystal Phase Quantum Well Emission with Digital Control.

    Science.gov (United States)

    Assali, S; Lähnemann, J; Vu, T T T; Jöns, K D; Gagliano, L; Verheijen, M A; Akopian, N; Bakkers, E P A M; Haverkort, J E M

    2017-09-18

    One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the zinc-blende (ZB) and wurtzite (WZ) phases. Such a crystal phase switching results in the formation of crystal phase quantum wells (CPQWs) and quantum dots (CPQDs). For GaP CPQWs, the inherent electric fields due to the discontinuity of the spontaneous polarization at the WZ/ZB junctions lead to the confinement of both types of charge carriers at the opposite interfaces of the WZ/ZB/WZ structure. This confinement leads to a novel type of transition across a ZB flat plate barrier. Here, we show digital tuning of the visible emission of WZ/ZB/WZ CPQWs in a GaP nanowire by changing the thickness of the ZB barrier. The energy spacing between the sharp emission lines is uniform and is defined by the addition of single ZB monolayers. The controlled growth of identical quantum wells with atomically flat interfaces at predefined positions featuring digitally tunable discrete emission energies may provide a new route to further advance entangled photons in solid state quantum systems.

  9. Phase-Controlled Magnetic Mirror for Wavefront Correction

    Science.gov (United States)

    Hagopian, John; Wollack, Edward

    2011-01-01

    Typically, light interacts with matter via the electric field and interaction with weakly bound electrons. In a magnetic mirror, a patterned nanowire is fabricated over a metallic layer with a dielectric layer in between. Oscillation of the electrons in the nanowires in response to the magnetic field of incident photons causes a re-emission of photons and operation as a "magnetic mirror." By controlling the index of refraction in the dielectric layer using a local applied voltage, the phase of the emitted radiation can be controlled. This allows electrical modification of the reflected wavefront, resulting in a deformable mirror that can be used for wavefront control. Certain applications require wavefront quality in the few-nanometer regime, which is a major challenge for optical fabrication and alignment of mirrors or lenses. The use of a deformable magnetic mirror allows for a device with no moving parts that can modify the phase of incident light over many spatial scales, potentially with higher resolution than current approaches. Current deformable mirrors modify the incident wavefront by using nano-actuation of a substrate to physically bend the mirror to a desired shape. The purpose of the innovation is to modify the incident wavefront for the purpose of correction of fabrication and alignment-induced wavefront errors at the system level. The advanced degree of precision required for some applications such as gravity wave detection (LISA - Laser Interferometer Space Antenna) or planet finding (FKSI - Fourier-Kelvin Stellar Interferometer) requires wavefront control at the limits of the current state of the art. All the steps required to fabricate a magnetic mirror have been demonstrated. The modification is to apply a bias voltage to the dielectric layer so as to change the index of refraction and modify the phase of the reflected radiation. Light is reflected off the device and collected by a phase-sensing interferometer. The interferometer determines the

  10. DSP and FPGA based system to control a wind turbine generator implementing a variable speed vectorial control method

    OpenAIRE

    Perales Esteve, Manuel Ángel; Barrero, Federico; Mora Jiménez, José Luis; Galván Díez, Eduardo; Carrasco Solís, Juan Manuel; García Franquelo, Leopoldo

    1997-01-01

    The purpose of this paper is to describe a DSP and FPGA control system to implement a variable speed vectorial control. Two semi-systems, both of them consisting on a DSP, a FPGA and A/D, D/A & digital I/O’s are used. Each one will control an inverter: The first inverter implements a variable speed vector control of the induction generator and the second one handle the power injected into the utility grid. Experimental results will be shown to confirm the validity of the proposed controller.

  11. Digital Interface Board to Control Phase and Amplitude of Four Channels

    Science.gov (United States)

    Smith, Amy E.; Cook, Brian M.; Khan, Abdur R.; Lux, James P.

    2011-01-01

    An increasing number of parts are designed with digital control interfaces, including phase shifters and variable attenuators. When designing an antenna array in which each antenna has independent amplitude and phase control, the number of digital control lines that must be set simultaneously can grow very large. Use of a parallel interface would require separate line drivers, more parts, and thus additional failure points. A convenient form of control where single-phase shifters or attenuators could be set or the whole set could be programmed with an update rate of 100 Hz is needed to solve this problem. A digital interface board with a field-programmable gate array (FPGA) can simultaneously control an essentially arbitrary number of digital control lines with a serial command interface requiring only three wires. A small set of short, high-level commands provides a simple programming interface for an external controller. Parity bits are used to validate the control commands. Output timing is controlled within the FPGA to allow for rapid update rates of the phase shifters and attenuators. This technology has been used to set and monitor eight 5-bit control signals via a serial UART (universal asynchronous receiver/transmitter) interface. The digital interface board controls the phase and amplitude of the signals for each element in the array. A host computer running Agilent VEE sends commands via serial UART connection to a Xilinx VirtexII FPGA. The commands are decoded, and either outputs are set or telemetry data is sent back to the host computer describing the status and the current phase and amplitude settings. This technology is an integral part of a closed-loop system in which the angle of arrival of an X-band uplink signal is detected and the appropriate phase shifts are applied to the Ka-band downlink signal to electronically steer the array back in the direction of the uplink signal. It will also be used in the non-beam-steering case to compensate for

  12. Optimal shifting control strategy in inertia phase of an automatic transmission for automotive applications

    Science.gov (United States)

    Meng, Fei; Tao, Gang; Zhang, Tao; Hu, Yihuai; Geng, Peng

    2015-08-01

    Shifting quality is a crucial factor in all parts of the automobile industry. To ensure an optimal gear shifting strategy with best fuel economy for a stepped automatic transmission, the controller should be designed to meet the challenge of lacking of a feedback sensor to measure the relevant variables. This paper focuses on a new kind of automatic transmission using proportional solenoid valve to control the clutch pressure, a speed difference of the clutch based control strategy is designed for the shift control during the inertia phase. First, the mechanical system is shown and the system dynamic model is built. Second, the control strategy is designed based on the characterization analysis of models which are derived from dynamics of the drive line and electro-hydraulic actuator. Then, the controller uses conventional Proportional-Integral-Derivative control theory, and a robust two-degree-of-freedom controller is also carried out to determine the optimal control parameters to further improve the system performance. Finally, the designed control strategy with different controller is implemented on a simulation model. The compared results show that the speed difference of clutch can track the desired trajectory well and improve the shift quality effectively.

  13. Computer Aided Design for Linear Control State Variable System (SVS).

    Science.gov (United States)

    1987-12-01

    li,1..11J of real; vrStepping,Steps step,stepp ings, Ternp 1,Temp2,valuei,value2 m, mplus , last rank,k~valueiplus kpius :integer; new Mfatrixi ,new...stepping]; new-matrixl[steps,stepping] :=B~steps,stepping]; End; End; mplus := size-i; value2:=valuel; For steps := 1 to mplus do Bgnmatrix...do BeginN biR mtrix~steps,ste ping] M= new matriX2 Lsteps,stepping,; -End; 1022 FILE: CONTROL.PAS Program Listing Page 2 End; mplus :=1; For steps :=1

  14. Tailoring Terahertz Propagation by Phase and Amplitude Control in Metasurfaces

    Science.gov (United States)

    Zheng, Jingjing; Zhang, Xueqian; Liu, Lixiang; Li, Quan; Singh, Leena; Han, Jiaguang; Yan, Fengping; Zhang, Weili

    2017-09-01

    Metasurfaces have been very successful at demonstrating the ability to control the wave propagation over the broad electromagnetic spectrum in recent years. The output wavefronts can be controlled at will, by encoding specially designed abrupt changes of electromagnetic parameters into the metasurfaces, such as phase and amplitude. Constituted by a single- or few-layer of planar structures, metasurfaces are straightforward in design and fabrication, thus promising many credible applications. Moreover, such control concept can be further extended to the surface wave regime. In this review, we present our recent progress on metasurfaces capable of tailoring the propagation of both free-space and surface terahertz waves. Following an introduction of the basic concept and theory, a number of unique terahertz metasurfaces are presented, showing the ability to device ultra-thin and compact functional terahertz components.

  15. Fuzzy Control Hardware for Segmented Mirror Phasing Algorithm

    Science.gov (United States)

    Roth, Elizabeth

    1999-01-01

    This paper presents a possible implementation of a control model developed to phase a system of segmented mirrors, with a PAMELA configuration, using analog fuzzy hardware. Presently, the model is designed for piston control only, but with the foresight that the parameters of tip and tilt will be integrated eventually. The proposed controller uses analog circuits to exhibit a voltage-mode singleton fuzzifier, a mixed-mode inference engine, and a current-mode defuzzifier. The inference engine exhibits multiplication circuits that perform the algebraic product composition through the use of operational transconductance amplifiers rather than the typical min-max circuits. Additionally, the knowledge base, containing exemplar data gained a priori through simulation, interacts via a digital interface.

  16. Input variable selection for data-driven models of Coriolis flowmeters for two-phase flow measurement

    Science.gov (United States)

    Wang, Lijuan; Yan, Yong; Wang, Xue; Wang, Tao

    2017-03-01

    Input variable selection is an essential step in the development of data-driven models for environmental, biological and industrial applications. Through input variable selection to eliminate the irrelevant or redundant variables, a suitable subset of variables is identified as the input of a model. Meanwhile, through input variable selection the complexity of the model structure is simplified and the computational efficiency is improved. This paper describes the procedures of the input variable selection for the data-driven models for the measurement of liquid mass flowrate and gas volume fraction under two-phase flow conditions using Coriolis flowmeters. Three advanced input variable selection methods, including partial mutual information (PMI), genetic algorithm-artificial neural network (GA-ANN) and tree-based iterative input selection (IIS) are applied in this study. Typical data-driven models incorporating support vector machine (SVM) are established individually based on the input candidates resulting from the selection methods. The validity of the selection outcomes is assessed through an output performance comparison of the SVM based data-driven models and sensitivity analysis. The validation and analysis results suggest that the input variables selected from the PMI algorithm provide more effective information for the models to measure liquid mass flowrate while the IIS algorithm provides a fewer but more effective variables for the models to predict gas volume fraction.

  17. Optically controlled phased-array antenna with PSK communications

    Science.gov (United States)

    Cooper, Martin J.; Sample, Peter; Lewis, Meirion F.; Wilson, Rebecca A.

    2004-11-01

    An optically controlled RF/microwave/mm-wave phased array antenna has been developed operating at 10 GHz with 30 kHz reconfiguration rate via the use of a micromachined silicon Spatial Light Modulator. A communications function has been demonstrated with a variety of Phase Shift Keying modulation schemes (BPSK, QPSK, MSK) at data rates up to 200 Mbit/s and low BER (<1×10-9). A single channel has been demonstrated at 35 GHz. The properties of photonic components are taken advantage of in several ways: (i) since the carrier frequency is derived from heterodyning of lasers, it is tuneable from almost DC-100 GHz, (ii) the use of optical fiber allows for EMI immune antenna remoting, and (iii) the wide information bandwidth of optical modulators, which in this configuration is carrier frequency independent. The above is achieved in a lightweight and compact format, with considerable scope for further reductions in size and weight.

  18. Ramsey-type phase control of free electron beams

    CERN Document Server

    Echternkamp, Katharina E; Schäfer, Sascha; Ropers, Claus

    2016-01-01

    Interference between multiple distinct paths is a defining property of quantum physics, where "paths" may involve actual physical trajectories, as in interferometry, or transitions between different internal (e.g. spin) states, or both. A hallmark of quantum coherent evolution is the possibility to interact with a system multiple times in a phase-preserving manner. This principle underpins powerful multi-dimensional optical and nuclear magnetic resonance spectroscopies and related techniques, including Ramsey's method of separated oscillatory fields used in atomic clocks. Previously established for atomic, molecular and quantum dot systems, recent developments in the optical quantum state preparation of free electron beams suggest a transfer of such concepts to the realm of ultrafast electron imaging and spectroscopy. Here, we demonstrate the sequential coherent interaction of free electron states with two spatially separated, phase-controlled optical near-fields. Ultrashort electron pulses are acted upon in ...

  19. Phase-controlled superconducting heat-flux quantum modulator

    Science.gov (United States)

    Giazotto, F.; Martínez-Pérez, M. J.

    2012-09-01

    We theoretically put forward the concept of a phase-controlled superconducting heat-flux quantum modulator. Its operation relies on phase-dependent heat current predicted to occur in temperature-biased Josephson tunnel junctions. The device behavior is investigated as a function of temperature bias across the junctions, bath temperature, and junctions asymmetry as well. In a realistic Al-based setup the structure could provide temperature modulation amplitudes up to ˜50 mK with flux-to-temperature transfer coefficients exceeding ˜125 mK/Φ0 below 1 K, and temperature modulation frequency of the order of a few MHz. The proposed structure appears as a promising building-block for the implementation of caloritronic devices operating at cryogenic temperatures.

  20. Multi-Variable Flocking Control for Multi-Agent Systems via a Received Signal Strength Indicator

    Institute of Scientific and Technical Information of China (English)

    Xin-Ping Guan; Shao-Min Xing; Xiao-Yuan Luo

    2011-01-01

    A novel flocking control approach is proposed for multi-agent systems by integrating the variables of velocities,motion directions,and positions of agents.A received signal strength indicator (RSSI) is applied as a variable to estimate the inter-distance between agents.A key parameter that contains the local information of agents is defined,and a multi-variable controller is proposed based on the parameter.For the position control of agents,the RSSI is introduced to substitute the distance as a control variable in the systems.The advantages of RSSI include that the relative distance between every two agents can be adjusted through the communication quality under different environments,and it can shun the shortage of the limit of sensors.Simulation studies demonstrate the effectiveness of the proposed control approach.

  1. Trabajar y habitar: dos variables espaciales del control postindustrial

    Directory of Open Access Journals (Sweden)

    Gabriela Rodríguez Fernández

    2008-07-01

    Full Text Available Este ensayo es una reflexión sobre las transformaciones en la forma de vivir la ciudad en el último siglo, unos cambios en los que el paso de una sociedad industrial a una sociedad telemática han alterado nuestras formas de habitar y trabajar, y por tanto de ser. Los espacios urbanos se construyen hoy siguiendo una lógica distinta a la que prevaleció en el pasado. Esta circunstancia produce nuevos modos de control y segregación, ocasiona dificultades para la composición de la propia identidad y conflictos por intolerancia; en conjunto, nos exige una flexibilidad sin precedentes que dificulta la constitución del sentido de comunidad.

  2. Adaptive control of a variable-impedance ankle-foot orthosis to assist drop-foot gait.

    Science.gov (United States)

    Blaya, Joaquin A; Herr, Hugh

    2004-03-01

    An active ankle-foot orthoses (AAFO) is presented where the impedance of the orthotic joint is modulated throughout the walking cycle to treat drop-foot gait. During controlled plantar flexion, a biomimetic torsional spring control is applied where orthotic joint stiffness is actively adjusted to minimize forefoot collisions with the ground. Throughout late stance, joint impedance is minimized so as not to impede powered plantar flexion movements, and during the swing phase, a torsional spring-damper control lifts the foot to provide toe clearance. To assess the clinical effects of variable-impedance control, kinetic and kinematic gait data were collected on two drop-foot participants wearing the AAFO. For each participant, zero, constant, and variable impedance control strategies were evaluated and the results were compared to the mechanics of three age, weight, and height matched normals. We find that actively adjusting joint impedance reduces the occurrence of slap foot allows greater powered plantar flexion and provides for less kinematic difference during swing when compared to normals. These results indicate that a variable-impedance orthosis may have certain clinical benefits for the treatment of drop-foot gait compared to conventional ankle-foot orthoses having zero or constant stiffness joint behaviors.

  3. Assessment of global phase uncertainty in case-control studies

    Directory of Open Access Journals (Sweden)

    van Houwelingen Hans C

    2009-09-01

    Full Text Available Abstract Background In haplotype-based candidate gene studies a problem is that the genotype data are unphased, which results in haplotype ambiguity. The measure 1 quantifies haplotype predictability from genotype data. It is computed for each individual haplotype, and for a measure of global relative efficiency a minimum value is suggested. Alternatively, we developed methods directly based on the information content of haplotype frequency estimates to obtain global relative efficiency measures: and based on A- and D-optimality, respectively. All three methods are designed for single populations; they can be applied in cases only, controls only or the whole data. Therefore they are not necessarily optimal for haplotype testing in case-control studies. Results A new global relative efficiency measure was derived to maximize power of a simple test statistic that compares haplotype frequencies in cases and controls. Application to real data showed that our proposed method gave a clear and summarizing measure for the case-control study conducted. Additionally this measure might be used for selection of individuals, who have the highest potential for improving power by resolving phase ambiguity. Conclusion Instead of using relative efficiency measure for cases only, controls only or their combined data, we link uncertainty measure to case-control studies directly. Hence, our global efficiency measure might be useful to assess whether data are informative or have enough power for estimation of a specific haplotype risk.

  4. DESIGN OF SINGLE PHASE FULLY CONTROLLED CONVERTER USING COSINE WAVE CROSSING CONTROL WITH VARIOUS PROTECTIONS

    Directory of Open Access Journals (Sweden)

    GENO PETER .P

    2010-09-01

    Full Text Available The single phase fully controlled converter is used to convert single phase A.C supply to D.C supply. Such converter finds application in dc motor loads for motoring and electrical braking of the motor. There are two types of control schemes to control the firing of thyristors, they are Cosine wave crossing control and Ramp comparator control. In this paper, cosine wave crossing control is used for the control circuit. The advantage of this scheme is that the output voltage is proportional to the control voltage ie., the output voltage is independent of the variation of input voltage. The various protections such as over current, short circuit, under voltage protections etc are included. The main objective of this project is to design an efficient, simple, robust and economical control circuit thereby making the fully controlled converter. The fully controlled converter uses four thyristors . It is a two quadrant converter was voltage polarity can reverse, but current direction cannot reverse because of unidirectional nature of thyristors. In this paper, I have presented the control circuit for the thyristors along with the protection circuits to control Dc Motors of rating 220V,5.8 A and 1500rpm .

  5. Two-phase Method without Any Artificial Variable%不需加人工变量的两阶段法

    Institute of Scientific and Technical Information of China (English)

    梁平; 张旭利; 张相斌

    2008-01-01

    A method is provided to achieve an initial basic feasible solution of a linear programming in this paper.This method dose not need introducing any artificial variable, but needs only solving an auxiliary linear programming.Compared with the traditional two-phase method, it has advantages of saving the memories and reducing the computational efforts.

  6. The Control Unit of a Single Phase Voltage Regulator

    CERN Document Server

    Colak, Ilknur

    2010-01-01

    Supplying regulated voltage to critical loads is an important topic for several years. This paper presents a single-phase electronic voltage regulator based on high frequency switching of an isolated transformer where primary side voltage is controlled by two full-bridge converters sharing a common DC bus and operating at 50Hz and 20kHz switching frequencies. This allows 50Hz induced voltage on the primary side of the transformer, regulated by high frequency switching. Depending on the input voltage, voltage at the secondary side of the transformer add to (boost mode) or subtract (buck mode) from the supply voltage, therefore, maintaining a regulated voltage value across the load. The regulator is controlled by a digital controller allowing fast dynamic response. A 5kVA single-phase voltage regulator is realized to verify the operation of the proposed algorithm. The experimental results show that regulator maintains constant voltage across the load both in step-up (low supply voltage) and step-down (high supp...

  7. Adaptive variable structure control based on backstepping for spacecraft with reaction wheels during attitude maneuver

    Institute of Scientific and Technical Information of China (English)

    SONG Bin; MA Guang-fu; LI Chuan-jiang

    2009-01-01

    An adaptive variable structure control method based on backstepping is proposed for the attitude maneuver problem of rigid spacecraft with reaction wheel dynamics in the presence of uncertain inertia matrix and external disturbances. The proposed control approach is a combination of the backstepping and the adaptive variable structure control. The cascaded structure of the attitude maneuver control system with reaction wheel dynamics gives the advantage for applying the backstepping method to construct Lyapunov functions. The robust stability to external disturbances and parametric uncertainty is guaranteed by the adaptive variable structure control. To validate the proposed control algorithm, numerical simulations using the proposed approach are performed for the attitude maneuver mission of rigid spacecraft with a configuration consisting of four reaction wheels for actuator and three magnetorquers for momentum unloading. Simulation results verify the effectiveness of the proposed control algorithm.

  8. Very-low-speed variable-structure control of sensorless induction machine drives without signal injection

    DEFF Research Database (Denmark)

    Lascu, Christian; Boldea, Ion; Blaabjerg, Frede

    2005-01-01

    , the "linear and variable-structure control", which realizes accurate and robust control in a wide speed range. Conventional DTC transient merits are preserved, while the steady-state behavior is significantly improved. The full-order state observer is a sliding-mode one, which does not require the rotor speed......A sensorless induction machine drive is presented, in which the principles of variable-structure control and direct torque control (DTC) are combined to ensure high-performance operation in the steady state and under transient conditions. The drive employs a new torque and flux controller...

  9. A Neural Network Controller for Variable-Speed Variable-Pitch Wind Energy Conversion Systems Using Generalized Minimum Entropy Criterion

    Directory of Open Access Journals (Sweden)

    Mifeng Ren

    2014-01-01

    Full Text Available This paper considers the neural network controller design problem for variable pitch wind energy conversion systems (WECS with non-Gaussian wind speed disturbances in the stochastic distribution control framework. The approach here is used to directly model the unknown control law based on a fixed neural network (the number of layers and nodes in a neural network is fixed without the need to construct a separate model for the WECS. In order to characterize the randomness of the WECS, a generalized minimum entropy criterion is established to train connection weights of the neural network. For the train purpose, both kernel density estimation method and sliding window technique are adopted to estimate the PDF of tracking error and entropies. Due to the unknown process dynamics, the gradient of the objective function in a gradient-descent-type algorithm is estimated using an incremental perturbation method. The proposed approach is illustrated on a simulated WECS with non-Gaussian wind speed.

  10. Enhanced Cross-Phase Modulation via Phase Control in a Quantum dot Nanostructure

    Institute of Scientific and Technical Information of China (English)

    郝向英; 郑安寿; 王英; 李小刚

    2012-01-01

    A four-level quantum dot (QD) nanostructure interacting with four fields (two weak near-infrared (NIR) pulses and two control fields) forms the well-known double-cascade configuration.We investigate the cross-phase modulation (XPM) between the two NIR pulses.The results show,in such a closed-loop scheme,that the XPM can be greatly enhanced,while the linear absorption and two-photon absorption (gain) can be efficiently depressed by tuning the relative phase among the applied fields.This protocol may have potential applications in NIR all-optical switch design and quantum information processing with the solid-state materials.

  11. Realizing quantum controlled phase flip through cavity QED

    Science.gov (United States)

    Xiao, Yun-Feng; Lin, Xiu-Min; Gao, Jie; Yang, Yong; Han, Zheng-Fu; Guo, Guang-Can

    2004-10-01

    We propose a scheme to realize quantum controlled phase flip (CPF) between two rare-earth ions embedded in the respective microsphere cavity via interacting with a single-photon pulse in sequence. The numerical simulations illuminate that the CPF gate between ions is robust and scalable with extremely high fidelity and low error rate. Our scheme is more applicable than other schemes presented before based on current laboratory cavity-QED technology, and it is possible to be used as an applied unit gate in future quantum computation and quantum communication.

  12. Realizing Quantum Controlled Phase Flip through Cavity-QED

    CERN Document Server

    Xiao, Y F; Gao, J; Yang, Y; Han, Z F; Guo, G C; Xiao, Yun-Feng; Lin, Xiu-Min; Gao, Jie; Yang, Yong; Han, Zheng-Fu; Guo, Guang-Can

    2004-01-01

    We propose a scheme to realize quantum controlled phase flip (CPF) between two rare earth ions embedded in respective microsphere cavity via interacting with a single-photon pulse in sequence. The numerical simulations illuminate that the CPF gate between ions is robust and scalable with extremely high fidelity and low error rate. Our scheme is more applicable than other schemes presented before based on current laboratory cavity-QED technology, and it is possible to be used as an applied unit gate in future quantum computation and quantum communication.

  13. A New Reaction-controlled Phase-transfer Catalyst System

    Institute of Scientific and Technical Information of China (English)

    Ming Qiang LI; Xi Gao JIAN; Gui Mei WANG; Yan YU

    2004-01-01

    A new reaction-controlled phase-transfer catalyst system was designed and synthesized. In this system, heteropolytungstate [C7H7N(CH3)3]9PW9O34 was used for catalytic epoxidation of cyclohexene with H2O2 as the oxidant. The conversion of H2O2 was 100% and the yield of cyclohexene oxide was 87.1% based on cyclohexene. Infrared spectra showed that both fresh catalyst and the recovered catalyst do have completely same absorption peak, indicating the structure of catalyst is very stability and can be recycled.

  14. Simulation of a Marine Controllable Phase-Compounding Excitation System

    Institute of Scientific and Technical Information of China (English)

    GAO Hai-bo; WU Fu-yuan; CHEN Hui

    2007-01-01

    We first established the mathematical model of a marine synchronous generator and its controllable phase-compounding excitation system, and then made a simulation sketch with Saber simulation software. According to "Regulations for the Construction and Classification of Ocean-going Steel Ships" of the China Classification Society (CCS) , some experiments are designed to verify the property of the simulation model. Some experiments, such as free start, load sudden on and off, have been completed, and the result indicates that the model conforms to the requirements of the rules very well. It is qualified for a marine electrical propulsion simulation.

  15. An active interferometer-stabilization scheme with linear phase control

    DEFF Research Database (Denmark)

    Vardhan Krishnamachari, Vishnu; Andresen, Esben Ravn; Potma, Eric Olaf

    2006-01-01

    We report a simple and robust computer-based active interferometer stabilization scheme which does not require modulation of the interfering beams and relies on an error signal which is linearly related to the optical path difference. In this setup, a non-collinearly propagating reference laser...... beam stabilizes the interference output of the laser light propagating collinearly through the interferometer. This stabilization scheme enables adjustable phase control with 20 ms switching times in the range from 0.02π radians to 6π radians at 632.8 nm....

  16. Security of continuous-variable quantum key distribution: towards a de Finetti theorem for rotation symmetry in phase space

    Energy Technology Data Exchange (ETDEWEB)

    Leverrier, A [Institut Telecom/Telecom ParisTech, CNRS LTCI, 46, rue Barrault, 75634 Paris Cedex 13 (France); Karpov, E; Cerf, N J [Quantum Information and Communication, Ecole Polytechnique, CP 165/59, Universite Libre de Bruxelles, 50 avenue F D Roosevelt, B-1050 Brussels (Belgium); Grangier, P [Laboratoire Charles Fabry, Institut d' Optique, CNRS, Universite Paris-Sud, Campus Polytechnique, RD 128, 91127 Palaiseau Cedex (France)], E-mail: anthony.leverrier@enst.fr

    2009-11-15

    Proving the unconditional security of quantum key distribution (QKD) is a highly challenging task as one needs to determine the most efficient attack compatible with experimental data. This task is even more demanding for continuous-variable QKD as the Hilbert space where the protocol is described is infinite dimensional. A possible strategy to address this problem is to make an extensive use of the symmetries of the protocol. In this paper, we investigate a rotation symmetry in phase space that is particularly relevant to continuous-variable QKD, and explore the way towards a new quantum de Finetti theorem that would exploit this symmetry and provide a powerful tool to assess the security of continuous-variable protocols. As a first step, a single-party asymptotic version of this quantum de Finetti theorem in phase space is derived.

  17. Security of continuous-variable quantum key distribution: towards a de Finetti theorem for rotation symmetry in phase space

    Science.gov (United States)

    Leverrier, A.; Karpov, E.; Grangier, P.; Cerf, N. J.

    2009-11-01

    Proving the unconditional security of quantum key distribution (QKD) is a highly challenging task as one needs to determine the most efficient attack compatible with experimental data. This task is even more demanding for continuous-variable QKD as the Hilbert space where the protocol is described is infinite dimensional. A possible strategy to address this problem is to make an extensive use of the symmetries of the protocol. In this paper, we investigate a rotation symmetry in phase space that is particularly relevant to continuous-variable QKD, and explore the way towards a new quantum de Finetti theorem that would exploit this symmetry and provide a powerful tool to assess the security of continuous-variable protocols. As a first step, a single-party asymptotic version of this quantum de Finetti theorem in phase space is derived.

  18. Power sharing algorithm for vector controlled six-phase AC motor with four customary three-phase voltage source inverter drive

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2015-09-01

    Full Text Available This paper considered a six-phase (asymmetrical induction motor, kept 30° phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs and all four dc sources are deliberately kept isolated. Therefore, zero-sequence/homopolar current components cannot flow. The original and effective power sharing algorithm is proposed in this paper with three variables (degree of freedom based on synchronous field oriented control (FOC. A standard three-level space vector pulse width modulation (SVPWM by nearest three vectors (NTVs approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/Simulink-PLECS software of whole ac drive system by observing the dynamic behaviors in different designed condition. Set of results are provided in this paper, which confirms a good agreement with theoretical development.

  19. Experimental analysis of fuzzy controlled energy efficient demand controlled ventilation economizer cycle variable air volume air conditioning system

    Directory of Open Access Journals (Sweden)

    Rajagopalan Parameshwaran

    2008-01-01

    Full Text Available In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.

  20. Increased Intrasubject Variability in Boys with ADHD across Tests of Motor and Cognitive Control

    Science.gov (United States)

    Rosch, Keri Shiels; Dirlikov, Benjamin; Mostofsky, Stewart H.

    2013-01-01

    Increased intrasubject variability (ISV), or short-term, within-person fluctuations in behavioral performance is consistently found in Attention-Deficit/Hyperactivity Disorder (ADHD). ADHD is also associated with impairments in motor control, particularly in boys. The results of the few studies that have examined variability in self-generated…

  1. Increased Intrasubject Variability in Boys with ADHD across Tests of Motor and Cognitive Control

    Science.gov (United States)

    Rosch, Keri Shiels; Dirlikov, Benjamin; Mostofsky, Stewart H.

    2013-01-01

    Increased intrasubject variability (ISV), or short-term, within-person fluctuations in behavioral performance is consistently found in Attention-Deficit/Hyperactivity Disorder (ADHD). ADHD is also associated with impairments in motor control, particularly in boys. The results of the few studies that have examined variability in self-generated…

  2. Development of digital flow control system for multi-channel variable-rate sprayers

    Science.gov (United States)

    Precision modulation of nozzle flow rates is a critical step for variable-rate spray applications in orchards and ornamental nurseries. An automatic flow rate control system activated with microprocessors and pulse width modulation (PWM) controlled solenoid valves was developed to control flow rates...

  3. DAC with LQR Control Design for Pitch Regulated Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Imran, Raja Muhammad; Hussain, Dil Muhammad Akbar; Soltani, Mohsen

    2014-01-01

    Disturbance Accommodation Control (DAC) is used to model and simulate a system with known disturbance waveform. This paper presents a control scheme to mitigate the effect of disturbances by using collective pitch control for the aboverated wind speed (Region III) for a variable speed wind turbin...

  4. VARIABLE FIRING RATE OIL BURNER USING PULSE FUEL FLOW CONTROL.

    Energy Technology Data Exchange (ETDEWEB)

    KRISHNA,C.R.; BUTCHER,T.A.; KAMATH,B.R.

    2004-10-01

    The residential oil burner market is currently dominated by the pressure-atomized retention head burner, which has an excellent reputation for reliability and efficiency. In this burner, oil is delivered to a fuel nozzle at pressures from 100 to 150 psi. In addition, to atomizing the fuel, the small, carefully controlled size of the nozzle exit orifice serves to control the burner firing rate. Burners of this type are currently available at firing rates of more than 0.5 gallons-per-hour (70,000 Btu/hr). Nozzles have been made for lower firing rates, but experience has shown that such nozzles suffer rapid fouling of the necessarily small passages, leading to bad spray patterns and poor combustion performance. Also, traditionally burners and the nozzles are oversized to exceed the maximum demand. Typically, this is figured as follows. The heating load of the house on the coldest day for the location is considered to define the maximum heat load. The contractor or installer adds to this to provide a safety margin and for future expansion of the house. If the unit is a boiler that provides domestic hot water through the use of a tankless heating coil, the burner capacity is further increased. On the contrary, for a majority of the time, the heating system is satisfying a much smaller load, as only rarely do all these demands add up. Consequently, the average output of the heating system has to be much less than the design capacity and this is accomplished by start and stop cycling operation of the system so that the time-averaged output equals the demand. However, this has been demonstrated to lead to overall efficiencies lower than the steady-state efficiency. Therefore, the two main reasons for the current practice of using oil burners much larger than necessary for space heating are the unavailability of reliable low firing rate oil burners and the desire to assure adequate input rate for short duration, high draw domestic hot water loads. One approach to solve this

  5. Inductance and Active Phase Vector Based Torque Control for Switched Reluctance Motor Drives.

    Science.gov (United States)

    Kalpathi, Ramani Raman

    The Switched Reluctance Motor (SRM) drive technology has developed significantly over the last few years. The simplicity in both motor design and power converter requirement along with the availability of high frequency, high power semiconductor switches have made SRMs compete with conventional adjustable speed drive technologies. The subject of winding current control in switched reluctance machines has always been associated with the shaft position information. The use of inductance for direct commutation control is the central subject of this dissertation. In contrast to the conventional methods based on position commutation, new methods of control based on inductance commutation are presented. The object of a commutation algorithm is to switch the currents in the phase coils, in order to provide continuous energy conversion with maximum torque output for a given unit of input current. Since torque production in a SRM is based on the concept of variable reluctance, it makes more sense to observe the instantaneous phase inductance or reluctance instead of estimating the rotor position. The inductance sensors observe the machine parameters and provide sufficient information on the electrical characteristics of the coils. This control strategy avoids the inductance to position transformation blocks conventionally used in SRM control systems. In a typical SRM, the phase coils have a nonlinear behavior of inductance due to effects of current saturation. Also the parameters of one phase coil differ from those of the other due to manufacturing tolerances or due to bearing wear. In such cases, the algorithms written during the stage of manufacturing may not be valid after parameter changes. Optimizing torque production in the event of phase asymmetry and saturation is developed in this research. Indirect sensors connected to the active phase coil of the SRM are based on sensing the flux level in the active coil. New commutation algorithms based on flux sensing concepts

  6. Dynamic phase-control of a rising sun magnetron using modulated and continuous current

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Gutierrez, Sulmer, E-mail: sulmer.a.fernandez.gutierrez@intel.com [Intel Corporation, 2111 NE 25th Ave, Hillsboro, Oregon 97214 (United States); Browning, Jim [Department of Electrical and Computer Engineering, Boise State University, Boise, Idaho 83725 (United States); Lin, Ming-Chieh [Department of Electrical and Biomedical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Smithe, David N. [Tech-X Corporation, 5621 Arapahoe Ave, Boulder, Colorado 80303 (United States); Watrous, Jack [Confluent Sciences, LLC, Albuquerque, New Mexico 87111 (United States)

    2016-01-28

    Phase-control of a magnetron is studied via simulation using a combination of a continuous current source and a modulated current source. The addressable, modulated current source is turned ON and OFF at the magnetron operating frequency in order to control the electron injection and the spoke phase. Prior simulation work using a 2D model of a Rising Sun magnetron showed that the use of 100% modulated current controlled the magnetron phase and allowed for dynamic phase control. In this work, the minimum fraction of modulated current source needed to achieve a phase control is studied. The current fractions (modulated versus continuous) were varied from 10% modulated current to 100% modulated current to study the effects on phase control. Dynamic phase-control, stability, and start up time of the device were studied for all these cases showing that with 10% modulated current and 90% continuous current, a phase shift of 180° can be achieved demonstrating dynamic phase control.

  7. Microfluidic generation of aqueous two-phase system (ATPS) droplets by controlled pulsating inlet pressures.

    Science.gov (United States)

    Moon, Byeong-Ui; Jones, Steven G; Hwang, Dae Kun; Tsai, Scott S H

    2015-06-07

    We present a technique that generates droplets using ultralow interfacial tension aqueous two-phase systems (ATPS). Our method combines a classical microfluidic flow focusing geometry with precisely controlled pulsating inlet pressure, to form monodisperse ATPS droplets. The dextran (DEX) disperse phase enters through the central inlet with variable on-off pressure cycles controlled by a pneumatic solenoid valve. The continuous phase polyethylene glycol (PEG) solution enters the flow focusing junction through the cross channels at a fixed flow rate. The on-off cycles of the applied pressure, combined with the fixed flow rate cross flow, make it possible for the ATPS jet to break up into droplets. We observe different droplet formation regimes with changes in the applied pressure magnitude and timing, and the continuous phase flow rate. We also develop a scaling model to predict the size of the generated droplets, and the experimental results show a good quantitative agreement with our scaling model. Additionally, we demonstrate the potential for scaling-up of the droplet production rate, with a simultaneous two-droplet generating geometry. We anticipate that this simple and precise approach to making ATPS droplets will find utility in biological applications where the all-biocompatibility of ATPS is desirable.

  8. Power maximization of variable-speed variable-pitch wind turbines using passive adaptive neural fault tolerant control

    Science.gov (United States)

    Habibi, Hamed; Rahimi Nohooji, Hamed; Howard, Ian

    2017-09-01

    Power maximization has always been a practical consideration in wind turbines. The question of how to address optimal power capture, especially when the system dynamics are nonlinear and the actuators are subject to unknown faults, is significant. This paper studies the control methodology for variable-speed variable-pitch wind turbines including the effects of uncertain nonlinear dynamics, system fault uncertainties, and unknown external disturbances. The nonlinear model of the wind turbine is presented, and the problem of maximizing extracted energy is formulated by designing the optimal desired states. With the known system, a model-based nonlinear controller is designed; then, to handle uncertainties, the unknown nonlinearities of the wind turbine are estimated by utilizing radial basis function neural networks. The adaptive neural fault tolerant control is designed passively to be robust on model uncertainties, disturbances including wind speed and model noises, and completely unknown actuator faults including generator torque and pitch actuator torque. The Lyapunov direct method is employed to prove that the closed-loop system is uniformly bounded. Simulation studies are performed to verify the effectiveness of the proposed method.

  9. Power maximization of variable-speed variable-pitch wind turbines using passive adaptive neural fault tolerant control

    Science.gov (United States)

    Habibi, Hamed; Rahimi Nohooji, Hamed; Howard, Ian

    2017-04-01

    Power maximization has always been a practical consideration in wind turbines. The question of how to address optimal power capture, especially when the system dynamics are nonlinear and the actuators are subject to unknown faults, is significant. This paper studies the control methodology for variable-speed variable-pitch wind turbines including the effects of uncertain nonlinear dynamics, system fault uncertainties, and unknown external disturbances. The nonlinear model of the wind turbine is presented, and the problem of maximizing extracted energy is formulated by designing the optimal desired states. With the known system, a model-based nonlinear controller is designed; then, to handle uncertainties, the unknown nonlinearities of the wind turbine are estimated by utilizing radial basis function neural networks. The adaptive neural fault tolerant control is designed passively to be robust on model uncertainties, disturbances including wind speed and model noises, and completely unknown actuator faults including generator torque and pitch actuator torque. The Lyapunov direct method is employed to prove that the closed-loop system is uniformly bounded. Simulation studies are performed to verify the effectiveness of the proposed method.

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

    Directory of Open Access Journals (Sweden)

    Logan Raj Lourdes Victor Raj

    2013-12-01

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

  11. Controllable thermal rectification realized in binary phase change composites.

    Science.gov (United States)

    Chen, Renjie; Cui, Yalong; Tian, He; Yao, Ruimin; Liu, Zhenpu; Shu, Yi; Li, Cheng; Yang, Yi; Ren, Tianling; Zhang, Gang; Zou, Ruqiang

    2015-03-09

    Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management.

  12. Controlled Phase Changes of Titania Using Nitrogen Plasma

    Science.gov (United States)

    Trejo-Tzab, R.; Caballero-Espada, Liliana; Quintana, P.; Ávila-Ortega, Alejandro; Medina-Esquivel, R. A.

    2017-01-01

    In this work, the development of a new crystallization technique is reported, using nitrogen plasma (AC) to obtain nanostructured anatase and rutile from amorphous titanium oxide (TiO2). This methodology increases throughput and minimizes thermal effects. Nanostructured amorphous TiO2 was obtained by the sol-gel method and subsequently subjected to AC treatment, at a controlled pressure, applying different powers and treatment times in order to obtain phase changes. The obtained samples were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The results show the crystallization in parallel with anatase and rutile phases with a proportion that is directly related to the applied power in the plasma and the treatment time. This technique allows us to obtain smaller crystals in comparison with those of classic thermal methodologies. It is also demonstrated that the application of plasma represents a novel and innovative method to obtain phase polymorphic changes in titanium oxide without needing to apply prolonged heat treatments at high temperatures and can therefore be taken into consideration as a technique with low energy costs, in comparison with conventional heat treatments.

  13. Controlling block copolymer phase behavior using ionic surfactant

    Science.gov (United States)

    Ray, D.; Aswal, V. K.

    2016-05-01

    The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO26PO39EO26)] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle-surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

  14. Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers

    Science.gov (United States)

    Improvements to reduce chemical waste and environmental pollution for variable-rate sprayers used in orchards and ornamental nurseries require inline injection techniques. A microprocessor controlled premixing inline injection system implementing a ceramic piston chemical metering pump and two small...

  15. Dynamical Autler-Townes control of a phase qubit.

    Science.gov (United States)

    Li, Jian; Paraoanu, G S; Cicak, Katarina; Altomare, Fabio; Park, Jae I; Simmonds, Raymond W; Sillanpää, Mika A; Hakonen, Pertti J

    2012-01-01

    Routers, switches, and repeaters are essential components of modern information-processing systems. Similar devices will be needed in future superconducting quantum computers. In this work we investigate experimentally the time evolution of Autler-Townes splitting in a superconducting phase qubit under the application of a control tone resonantly coupled to the second transition. A three-level model that includes independently determined parameters for relaxation and dephasing gives excellent agreement with the experiment. The results demonstrate that the qubit can be used as a ON/OFF switch with 100 ns operating time-scale for the reflection/transmission of photons coming from an applied probe microwave tone. The ON state is realized when the control tone is sufficiently strong to generate an Autler-Townes doublet, suppressing the absorption of the probe tone photons and resulting in a maximum of transmission.

  16. Research on Open-Closed-Loop Iterative Learning Control with Variable Forgetting Factor of Mobile Robots

    Directory of Open Access Journals (Sweden)

    Hongbin Wang

    2016-01-01

    Full Text Available We propose an iterative learning control algorithm (ILC that is developed using a variable forgetting factor to control a mobile robot. The proposed algorithm can be categorized as an open-closed-loop iterative learning control, which produces control instructions by using both previous and current data. However, introducing a variable forgetting factor can weaken the former control output and its variance in the control law while strengthening the robustness of the iterative learning control. If it is applied to the mobile robot, this will reduce position errors in robot trajectory tracking control effectively. In this work, we show that the proposed algorithm guarantees tracking error bound convergence to a small neighborhood of the origin under the condition of state disturbances, output measurement noises, and fluctuation of system dynamics. By using simulation, we demonstrate that the controller is effective in realizing the prefect tracking.

  17. Variable-structure approaches analysis, simulation, robust control and estimation of uncertain dynamic processes

    CERN Document Server

    Senkel, Luise

    2016-01-01

    This edited book aims at presenting current research activities in the field of robust variable-structure systems. The scope equally comprises highlighting novel methodological aspects as well as presenting the use of variable-structure techniques in industrial applications including their efficient implementation on hardware for real-time control. The target audience primarily comprises research experts in the field of control theory and nonlinear dynamics but the book may also be beneficial for graduate students.

  18. The performance analysis and calculation for variable frequency speed control motors with the rotor structure optimized

    Institute of Scientific and Technical Information of China (English)

    CAO Jun-ci; LI Wei-li

    2005-01-01

    In the paper, the method to optimize the rotor structure in variable frequency speed control motors is introduced. The saturation and the skin effect are considered and 2D no-load and load electromagnetic field is calculated in finite elements for a variable frequency speed control motor before and after optimization. Finally,no-load current and operation performance before and after optimization are obtained and the two results are contrasted.

  19. USING RANDOM PROPORTIONAL PULSE FEEDBACK OF SYSTEM VARIABLES TO CONTROL CHAOS AND HYPERCHAOS

    Institute of Scientific and Technical Information of China (English)

    LUO XIAO-SHU; WANG BING-HONG; GAO YUAN; JIANG FENG

    2001-01-01

    A method that allows one to control chaotic and hyperchaotic systems by a random proportional pulse feedback of system variables is proposed. This method is illustrated with the Rossler chaotic and the complex Lorenz-Harken hyperchaotic systems, and a better control result is obtained. The advantage of this method is that just one perturbed system variable is enough to obtain a stabilized periodic orbit.

  20. Differentiating Between Precursor and Control Variables When Analyzing Reasoned Action Theories

    OpenAIRE

    Hennessy, Michael; Bleakley, Amy; FISHBEIN, MARTIN; Brown, Larry; DiClemente, Ralph; Romer, Daniel; Valois, Robert; Vanable, Peter A.; Carey, Michael P.; Salazar, Laura

    2009-01-01

    This paper highlights the distinction between precursor and control variables in the context of reasoned action theory. Here the theory is combined with structural equation modeling to demonstrate how age and past sexual behavior should be situated in a reasoned action analysis. A two wave longitudinal survey sample of African-American adolescents is analyzed where the target behavior is having vaginal sex. Results differ when age and past behavior are used as control variables and when they ...

  1. Structure Analysis of Typical Fuzzy Controllers with Unequally Spaced Fuzzy Sets for Input and Output Variables

    Institute of Scientific and Technical Information of China (English)

    FAN Xingzhe; ZHANG Naiyao; LINing

    2001-01-01

    In this paper, a kind of typical fuzzycontrollers is defined, which have two inputs (e and△c) and one output (△u); triangular, symmetric andfull-overlapped membership functions for input vari-ables; singleton and symmetric membership func-tions for output variable; linear fuzzy control rules;Sum-Product inference method, and weighted meanmethod for defuzzification. For this kind of typicalfuzzy controllers we have analyzed their analyticalstructure, limiting structure and local stability.

  2. Maxwell's Law Based Models for Liquid and Gas Phase Diffusivities in Variably-Saturated Soil

    DEFF Research Database (Denmark)

    Mamamoto, Shoichiro; Møldrup, Per; Kawamoto, Ken

    2012-01-01

    particles (clay and organic matter), FINESvol. The resulting LIquid and GAs diffusivity and tortuosity (LIGA) models were tested against D-s,D-g and D-s,D-l data for differently-textured soils and performed well against the measured data across soil types. A sensitivity analysis using the new Maxwell's Law......The gas diffusion coefficient (D-s,D-g) and solute diffusion coefficient (D-s,D-l) and their dependencies on fluid content (kappa) (equal to soil-air content theta for D-s,D-g and soil-water content epsilon for D-s,D-l) are controlling factors for gas and solute transport in variably saturated......-s,D-l). Different percolation threshold terms adopted from recent studies for gas (D-s,D-g) and solute (D-s,D-l) diffusion were applied. For gas diffusion, epsilon(th) was a function of bulk density (total porosity), while for solute diffusion theta(th) was best described by volumetric content of finer soil...

  3. Concentration-driven phase control for low temperature synthesis of phase-pure anatase and rutile titanium oxide.

    Science.gov (United States)

    Wang, Zhifeng; Xiao, Chunyan; Yamada, Shuhei; Yoshinaga, Kohji; Bu, Xiu R; Zhang, Ming

    2015-06-15

    It is highly desirable to develop controlled synthetic methods at low temperature (anatase without the use of any additives or surfactants or external acids. The formation of crystalline phases is found to be dependent on reaction temperature and highly dependent on concentration. Phase-pure rutile is obtained in two concentration zones while phase-pure anatase is obtained in one concentration zone. The relationship between phases and reaction conditions (concentration and temperature) fits well with the nucleation diffusion rate model.

  4. Stability of Hand Force Production: I. Hand Level Control Variables and Multi-Finger Synergies.

    Science.gov (United States)

    Reschechtko, Sasha; Latash, Mark L

    2017-09-13

    We combined the theory of neural control of movement with referent coordinates and the uncontrolled manifold hypothesis to explore synergies stabilizing the hand action in accurate four-finger pressing tasks. In particular, we tested a hypothesis on two classes of synergies - those among the four fingers and those within a pair of control variables - stabilizing hand action under visual feedback and disappearing without visual feedback. Subjects performed four-finger total force and moment production tasks under visual feedback; the feedback was later partially or completely removed. The "inverse piano" device was used to lift and lower the fingers smoothly at the beginning and at the end of each trial. These data were used to compute pairs of hypothetical control variables. Inter-trial analysis of variance within the finger force space was used to quantify multi-finger synergies stabilizing both force and moment. A data permutation method was used to quantify synergies among control variables. Under visual feedback, synergies in the spaces of finger forces and hypothetical control variables were found to stabilize total force. Without visual feedback, the subjects showed a force drift to lower magnitudes and a moment drift toward pronation. This was accompanied by disappearance of the four-finger synergies and strong attenuation of the control-variable synergies. The indices of the two types of synergies correlated with each other. The findings are interpreted within the scheme with multiple levels of abundant variables. Copyright © 2017, Journal of Neurophysiology.

  5. Role of the Indonesian Throughflow in controlling regional mean climate and rainfall variability

    Science.gov (United States)

    England, Matthew H.; Santoso, Agus; Phipps, Steven; Ummenhofer, Caroline

    2017-04-01

    The role of the Indonesian Throughflow (ITF) in controlling regional mean climate and rainfall is examined using a coupled ocean-atmosphere general circulation model. Experiments employing both a closed and open ITF are equilibrated to steady state and then 200 years of natural climatic variability is assessed within each model run, with a particular focus on the Indian Ocean region. Opening of the ITF results in a mean Pacific-to-Indian throughflow of 21 Sv (1 Sv = 106 m3 sec-1), which advects warm west Pacific waters into the east Indian Ocean. This warm signature is propagated westward by the mean ocean flow, however it never reaches the west Indian Ocean, as an ocean-atmosphere feedback in the tropics generates a weakened trade wind field that is reminiscent of the negative phase of the Indian Ocean Dipole (IOD). This is in marked contrast to the Indian Ocean response to an open ITF when examined in ocean-only model experiments; which sees a strengthening of both the Indian Ocean South Equatorial Current and the Agulhas Current. The coupled feedback in contrast leads to cooler conditions over the west Indian Ocean, and an anomalous zonal atmospheric pressure gradient that enhances the advection of warm moist air toward south Asia and Australia. This leaves the African continent significantly drier, and much of Australia and southern Asia significantly wetter, in response to the opening of the ITF. Given the substantial interannual variability that the ITF exhibits in the present-day climate system, and the restriction of the ITF gateway in past climate eras, this could have important implications for understanding past and present regional rainfall patterns around the Indian Ocean and over neighbouring land-masses.

  6. Algal bloom sedimentation induces variable control of lake eutrophication by phosphorus inactivating agents

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Changhui [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Bai, Leilei [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Graduate University of Chinese Academy of Sciences (China); Jiang, He-Long, E-mail: hljiang@niglas.ac.cn [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Xu, Huacheng [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-07-01

    Lake eutrophication typically occurs with a syndrome of algae breeding and biomass accumulation (e.g., algal blooms). Therefore, the effect of algal bloom sedimentation on eutrophication control by phosphorus (P) inactivating agents was assessed herein. Three commercial products, including aluminum (Al) sulfate, iron (Fe) sulfate, and a lanthanum-modified clay (Phoslock®), as well as one easily available by-product, drinking water treatment residue (DWTR), were selected. The most important finding was that during algae sedimentation, P immobilization from the overlying water by Al, Phoslock®, and DWTR was dominated by a long-term slow phase (> 150 d), while Fe has limited effectiveness on the immobilization. Further analysis indicated that the algae sedimentation effect was mainly due to the slow release of P from algae, leading to relatively limited P available for the inactivating agents. Then, a more unfavorable effect on the P immobilization capability of inactivating agents was caused by the induced anaerobic conditions, the released organic matter from algae, and the increased sulfide in the overlying water and sediments during sedimentation. Overall, algae sedimentation induced variable control of eutrophication by P inactivating agents. Accordingly, recommendations for future works about algal lake restoration were also proposed. - Highlights: • A long-term P immobilization by Phoslock®, DWTR, and Al was observed. • Fe had limited effectiveness on P pollution control for overlying water. • Al and Fe enhanced sulfur reduction, while DWTR and Phoslock® had minor effect. • The sedimentation reduced Al and La release from agents, but enhanced Fe release. • The agents changed organic matter compositions and structures in water columns.

  7. Validation of a new control system for Elekta accelerators facilitating continuously variable dose rate

    DEFF Research Database (Denmark)

    Bertelsen, Anders; Lorenzen, Ebbe L; Brink, Carsten

    2011-01-01

    Elekta accelerators controlled by the current clinically used accelerator control system, Desktop 7.01 (D7), uses binned variable dose rate (BVDR) for volumetric modulated arc therapy (VMAT). The next version of the treatment control system (Integrity) supports continuously variable dose rate (CVDR......) as well as BVDR. Using CVDR opposed to BVDR for VMAT has the potential of reducing the treatment time but may lead to lower dosimetric accuracy due to faster moving accelerator parts. Using D7 and a test version of Integrity, differences in ability to control the accelerator, treatment efficiency...

  8. PARTIAL STABILIZATION OF A CLASS OF CONTINUOUS NONLINEAR CONTROL SYSTEMS WITH SEPARATED VARIABLES

    Institute of Scientific and Technical Information of China (English)

    Jigui JIAN; Xiaoxin LIAO

    2005-01-01

    In this paper, the partial stabilization problem for a class of nonlinear continuous control systems with separated variables is investigated. Several stabilizing controllers are constructed based on the partial stability theory of Lyapunov and the property of M-matrix, and some of these stabilizing controllers are only related to partial state variables. The controllers constructed here are shown to guarantee partial asymptotic stability of the closed-loop systems and these sufficient conditions may give some instructions to actual engineering application. A example is also given to illustrate the design method.

  9. Telmisartan exerts sustained blood pressure control and reduces blood pressure variability in metabolic syndrome by inhibiting sympathetic activity.

    Science.gov (United States)

    Sueta, Daisuke; Koibuchi, Nobutaka; Hasegawa, Yu; Toyama, Kensuke; Uekawa, Ken; Katayama, Tetsuji; Ma, MingJie; Nakagawa, Takashi; Ogawa, Hisao; Kim-Mitsuyama, Shokei

    2014-12-01

    Accumulating evidence on blood pressure (BP) reduction with various angiotensin II receptor blockers (ARBs) show that the magnitudes and durations of BP control differ across ARBs. However, the mechanism of ARBs is unknown. This work was undertaken to compare telmisartan and valsartan in duration of BP control, BP variability, and effects on the autonomic nervous system. Using radiotelemetry combined with spectral analysis with a fast Fourier transformation algorithm, we compared the effects of various doses of telmisartan and valsartan on BP and its variability during dark (active phase) and light (inactive phase) periods over 5 weeks in SHR/NDmcr-cp(+/+)(SHRcp) rats, a model of metabolic syndrome. We also compared the effects of these ARBs on autonomic nervous system, central oxidative stress, and inflammation in SHRcp rats. Telmisartan exerted a longer-lasting BP-lowering effect and greater attenuation of BP variability in SHRcp than valsartan. Telmisartan decreased low frequency power of systolic BP and increased spontaneous baroreflex gain in SHRcp during both the dark and light periods more than valsartan. Telmisartan reduced 24-hour urinary norepinephrine excretion more than valsartan. Furthermore, telmisartan attenuated oxidative stress and the numbers of gp91(phox)-positive cells and activated microglia and astrocytes in the rostral ventrolateral medulla of SHRcp rats more than valsartan. The superiority of telmisartan over valsartan in sustained BP control and reduction of BP variability was attributed to more suppression of sympathetic activity and more improvement of baroreceptor reflex. The greater suppression of sympathetic activity by telmisartan appeared to be partially mediated by a stronger amelioration of central oxidative stress. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Model Predictive Control of a Nonlinear System with Known Scheduling Variable

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

    2012-01-01

    the control problem of the nonlinear system is simplied into a quadratic programming. Wind turbine is chosen as the case study and we choose wind speed as the scheduling variable. Wind speed is measurable ahead of the turbine, therefore the scheduling variable is known for the entire prediction horizon.......Model predictive control (MPC) of a class of nonlinear systems is considered in this paper. We will use Linear Parameter Varying (LPV) model of the nonlinear system. By taking the advantage of having future values of the scheduling variable, we will simplify state prediction. Consequently...

  11. Generation of entanglement in quantum parametric oscillators using phase control.

    Science.gov (United States)

    Gonzalez-Henao, J C; Pugliese, E; Euzzor, S; Abdalah, S F; Meucci, R; Roversi, J A

    2015-08-19

    The control of quantum entanglement in systems in contact with environment plays an important role in information processing, cryptography and quantum computing. However, interactions with the environment, even when very weak, entail decoherence in the system with consequent loss of entanglement. Here we consider a system of two coupled oscillators in contact with a common heat bath and with a time dependent oscillation frequency. The possibility to control the entanglement of the oscillators by means of an external sinusoidal perturbation applied to the oscillation frequency has been theoretically explored. We demonstrate that the oscillators become entangled exactly in the region where the classical counterpart is unstable, otherwise when the classical system is stable, entanglement is not possible. Therefore, we can control the entanglement swapping from stable to unstable regions by adjusting amplitude and phase of our external controller. We also show that the entanglement rate is approximately proportional to the real part of the Floquet coefficient of the classical counterpart of the oscillators. Our results have the intriguing peculiarity of manipulating quantum information operating on a classical system.

  12. Practical robust stabilization of PMAC servo drive based on continuous variable structure control

    Energy Technology Data Exchange (ETDEWEB)

    Grcar, B.; Cafuta, P.; Znidaric, M. [Univ. of Maribor (Slovenia). Faculty of Electrical Engineering and Computer Sciences

    1996-12-01

    In the paper the two stage control design of a high performance PMAC servo drive is described. In the first stage the nominal PMAC motor model is discussed as an analytical nonlinear system, transformed into the controllable canonical Brunovsky`s forms on the basis of input-output linearization. The influence of the load torque is considered implicitly by introducing the disturbance observer. Due to the sensitivity of the nominal model based control to parameter perturbations the linear tracking control is extended in the second stage by a continuous variable structure stabilizing control derived from Lyapunov`s function of the augmented feedback system. The design of the variable structure control requires no knowledge of the upper bounds of the perturbation function; instead, it considers the variable bounds of the available control signal. Undesired chattering of states and controlled variables are excluded. The introduced two stage control design assures practical robust stabilization for the class of bounded nonlinear perturbations satisfying the matching conditions without affecting the relative degree of the feedback system. Experimental results of the proposed PMAC servo drive control are presented.

  13. HD 240121 - An ACV variable showing anti-phase variations of the B and V light curves

    Science.gov (United States)

    Gröbel, Rainer; Hümmerich, Stefan; Paunzen, Ernst; Bernhard, Klaus

    2017-01-01

    The variability of HD 240121 = BD+59 2602 was first suspected by Särg and Wramdemark (1970) and later confirmed by Gröbel R. (1992a,b). Because of the observed anti-phase variations of the B and V light curves, the latter author tentatively suggested an ACV type. Apart from its inclusion in the catalog of New Suspected Variables (NSV 25977), no further investigations of the star have been published. HD 240121 was included into our target list of ACV candidates and investigated in order to determine the reason for the observed brightness variations. All available information on HD 240121 were collected via an exhaustive data mining procedure. Data from Gröbel (1992a,b) were re-analysed and photometric observations from the NSVS and Hipparcos archives were procured and investigated. Line-of-sight reddening and stellar parameters were calculated from archival photometric data. HD 240121 is a young, late B-type CP2 star of the silicon subgroup. The observed period, amplitude of light variations and variability pattern (anti-phase variations) are typical of ACV variables. The occurrence of anti-phase variations of the B and V light curves is rarely observed and points to the existence of a null wavelength in the visual spectrum. We therefore strongly encourage further multi-colour photometric observations of this star.

  14. DERIVATION AND INTEGRAL SLIDING MODE VARIABLE STRUCTURE CONTROL OF HYDRAULIC VELOCITY TRACKING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Wei Jianhua; Guan Cheng

    2005-01-01

    The velocity tracking control of a hydraulic servo system is studied. Since the dynamics of the system are highly nonlinear and have large extent of model uncertainties, such as big changes in load and parameters, a derivation and integral sliding mode variable structure control scheme (DI-SVSC) is proposed. An integral controller is introduced to avoid the assumption that the derivative of desired signal must be known in conventional sliding mode variable structure control, a nonlinear derivation controller is used to weaken the chattering of system. The design method of switching function in integral sliding mode control, nonlinear derivation coefficient and controllers of DI-SVSC is presented respectively. Simulation shows that the control approach is of nice robustness and improves velocity tracking accuracy considerably.

  15. State-variable control of shunt FACTS devices using phasor measurements

    Energy Technology Data Exchange (ETDEWEB)

    Machowski, J. [Warsaw University of Technology, Instytut Elektroenergetyki, Koszykowa 75, 00-662 Warszawa (Poland); Bialek, J.W. [University of Edinburgh, School of Engineering and Electronics, King' s Buildings, Mayfield Road, Edinburgh EH9 3JL (United Kingdom)

    2008-01-15

    This paper addresses the problem of state-variable stabilizing control of power system using shunt FACTS devices. This stabilizing control is activated in the transient state of a power system and is supplementary with respect to the main steady-state control of a FACTS device. Stabilizing control laws have been derived for a non-linear multi-machine system model using direct Lyapunov method with the aim to maximize the rate of energy dissipation during power swings and therefore maximization of damping. The proposed control strategy is executed by a non-linear multi-loop controller with rotor angles and speed deviations of synchronous generators used as the input signals. The input signals, obtained from a phasor measurement system, are necessary only from a small area around the controlled shunt FACTS device. Validity of the proposed state-variable control has been confirmed by computer simulation for a small multi-machine test system. (author)

  16. Correlations of control variables for horizontal background error covariance modeling on cubed-sphere grid

    Science.gov (United States)

    Kwun, Jihye; Song, Hyo-Jong; Park, Jong-Im

    2013-04-01

    Background error covariance matrix is very important for variational data assimilation system, determining how the information from observed variables is spread to unobserved variables and spatial points. The full representation of the matrix is impossible because of the huge size so the matrix is constructed implicitly by means of a variable transformation. It is assumed that the forecast errors in the control variables chosen are statistically independent. We used the cubed-sphere geometry based on the spectral element method which is better for parallel application. In cubed-sphere grids, the grid points are located at Gauss-Legendre-Lobatto points on each local element of 6 faces on the sphere. The two stages of the transformation were used in this study. The first is the variable transformation from model to a set of control variables whose errors are assumed to be uncorrelated, which was developed on the cubed sphere-using Galerkin method. Winds are decomposed into rotational part and divergent part by introducing stream function and velocity potential as control variables. The dynamical constraint for balance between mass and wind were made by applying linear balance operator. The second is spectral transformation which is to remove the remaining spatial correlation. The bases for the spectral transform were generated for the cubed-sphere grid. 6-hr difference fields of shallow water equation (SWE) model run initialized by variational data assimilation system were used to obtain forecast error statistics. In the horizontal background error covariance modeling, the regression analysis of the control variables was performed to define the unbalanced variables as the difference between full and correlated part. Regression coefficient was used to remove the remaining correlations between variables.

  17. Speed Sensorless Vector Control of Unbalanced Three-Phase Induction Motor with Adaptive Sliding Mode Control

    Directory of Open Access Journals (Sweden)

    Mohammad Jannati

    2014-05-01

    Full Text Available This paper presents a technique for speed sensorless Rotor Flux Oriented Control (RFOC of 3-phase Induction Motor (IM under open-phase fault (unbalanced or faulty IM. The presented RFOC strategy is based on rotational transformation. An adaptive sliding mode control system with an adaptive switching gain is proposed instead of the speed PI controller. Using an adaptive sliding mode control causes the proposed speed sensorless RFOC drive system to become insensitive to uncertainties such as load disturbances and parameter variations. Moreover, with adaptation of the sliding switching gain, calculation of the system uncertainties upper bound is not needed. Finally, simulation results have been presented to confirm the good performance of the proposed method.

  18. Force control compensation method with variable load stiffness and damping of the hydraulic drive unit force control system

    Science.gov (United States)

    Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong

    2016-05-01

    Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this

  19. Study on Variable Capacity Control Mechanism of Scroll Compressor for Automotive Air Conditioner

    Science.gov (United States)

    Hirano, Takahisa; Shigeoka, Tetsuo

    As for the automotive air conditioner, (1) to keep the automotive cabin temperature in a comfortable region, (2) to improve driving feeling, (3) to drive the air conditioning system economically through all seasons, are universally required. Recently, from these points, compressors with variable capacity control mechanism for automotive air conditioners have been remarkably requested. We have developed a scroll comoressor with variable capacity control mechanism. The capacity control mechanism, which changes the channel area of the bypass hole continuously, according to the suction gas pressure and the discharge gas pressure, has been developed. In this report, we describe the mechanism of variable capacity control and the performance simulation program that has been developed for the scroll compressor. Further, we describe the measuring results of cylinder pressure behavior, the results of energy loss analysis and the effect of comfort, drivability, power saving in the refrigerating cycle using the developed capacity control compressor.

  20. Variable-delay feedback control of unstable steady states in retarded time-delayed systems

    CERN Document Server

    Gjurchinovski, Aleksandar; 10.1103/PhysRevE.81.016209

    2010-01-01

    We study the stability of unstable steady states in scalar retarded time-delayed systems subjected to a variable-delay feedback control. The important aspect of such a control problem is that time-delayed systems are already infinite-dimensional before the delayed feedback control is turned on. When the frequency of the modulation is large compared to the system's dynamics, the analytic approach consists of relating the stability properties of the resulting variable-delay system with those of an analogous distributed delay system. Otherwise, the stability domains are obtained by a numerical integration of the linearized variable-delay system. The analysis shows that the control domains are significantly larger than those in the usual time-delayed feedback control, and that the complexity of the domain structure depends on the form and the frequency of the delay modulation.

  1. Complex state variable- and disturbance observer-based current controllers for AC drives

    DEFF Research Database (Denmark)

    Dal, Mehmet; Teodorescu, Remus; Blaabjerg, Frede

    2013-01-01

    , extracted by a disturbance observer and then injected into the current controller. In this study, a revised version of a disturbance observer-based controller and a well known complex variable model-based design with a single set of complex pole are compared in terms of design aspects and performance...... of the parameter and the cross-coupling effect. Moreover, it provides a better performance, smooth and low noisy operation with respect to the complex variable controller....... of the stator current. In order to improve the current control performance an alternative current control strategy was proposed previously aiming to avoid the undesired cross-coupling and non-linearities between the state variables. These effects are assumed as disturbances arisen in the closed-loop path...

  2. Origin and control of instability in SCR/triac three-phase motor controllers

    Science.gov (United States)

    Dearth, J. J.

    1982-01-01

    The energy savings and reactive power reduction functions initiated by the power factor controller (PFC) are discussed. A three-phase PFC with soft start is examined analytically and experimentally to determine how well it controls the open loop instability and other possible modes of instability. The detailed mechanism of the open loop instability is determined and shown to impose design constraints on the closed loop system. The design is shown to meet those constraints.

  3. Differentiating between precursor and control variables when analyzing reasoned action theories.

    Science.gov (United States)

    Hennessy, Michael; Bleakley, Amy; Fishbein, Martin; Brown, Larry; Diclemente, Ralph; Romer, Daniel; Valois, Robert; Vanable, Peter A; Carey, Michael P; Salazar, Laura

    2010-02-01

    This paper highlights the distinction between precursor and control variables in the context of reasoned action theory. Here the theory is combined with structural equation modeling to demonstrate how age and past sexual behavior should be situated in a reasoned action analysis. A two wave longitudinal survey sample of African-American adolescents is analyzed where the target behavior is having vaginal sex. Results differ when age and past behavior are used as control variables and when they are correctly used as precursors. Because control variables do not appear in any form of reasoned action theory, this approach to including background variables is not correct when analyzing data sets based on the theoretical axioms of the Theory of Reasoned Action, the Theory of Planned Behavior, or the Integrative Model.

  4. Identifying Spatially Inhomogeneous Relationships Between Drainage Density and Its Controlling Variables

    Science.gov (United States)

    Stepinski, T.; Ranatunga, T.; Jasiewicz, J.

    2011-12-01

    Spatial variation of the value of drainage density (D) is observed on variety of scales. It is attributed to a nonuniform distribution of variables that exert control over D. Comprehensive understanding of the dependence of D on its controlling factors is lacking because of complex, nonlinear character of such dependence. This study presents the use of the regression tree technique to identify different relationships between D and its controlling variables across the conterminous United States. Local drainage density (response variable) is calculated on a 4 km-size regular grid from high resolution stream network data from the National Hydrographic Dataset. Explanatory variables pertaining to geology, soil, terrain, climate, land cover, and vegetation density are also calculated on the same grid. The resulting grids are fed to a GUIDE algorithm to build a regression tree. The algorithm performs "regression by parts" - it hierarchically partitions the dataset so as to increase the accuracy of linear regression in each partition. Each final partition (a terminal node of the tree) contains entries in the dataset (cells in a grid) for which a good-fit linear relation between D and its controlling variables can be established. Ranges of explanatory variables in each node are determined by the path in the tree, and spatial extent (footprint of relationship) of the node is mapped. Collection of all such relations and their footprints provides comprehensive understanding of dependence of D on its controlling factors.

  5. Vibration control of flexible spacecraft actuated by piezoceramics via variable structure strategy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presented a hybrid control scheme to vibration reduction of flexible spacecraft during rotational maneuver by using variable structure output feedback control(VSOFC)and piezoelectric materials. The control configuration included the attitude controller based on VSOFC method and vibration attenuator designed by constant-gain negative velocity feedback control. The attitude controller consisted of a linear feedback term and a discontinuous feedback term. With the presence of this attitude controller, an additional flexible control system acting on the flexible parts can be designed for vibration control. Compared with conventional proportional-derivative(PD)control, the developed control scheme guarantees not only the stability of the closed-loop system, but also yields better performance and robustness in the presence of parametric uncertainties and external disturbance. Simulation results are presented for the spacecraft model to show the effectiveness of the proposed control techniques.

  6. Simulation of Few Bifurcation Phase Diagrams of Belousov-Zhabotinsky Reaction with Eleven Variable Chaotic Model in CSTR

    Directory of Open Access Journals (Sweden)

    B. Swathi

    2009-01-01

    Full Text Available Simulation of the Gyorgyi, Rempe and Field eleven variable chaotic model in CSTR [Continuously Stirred Tank Reactor] is performed with respect to the concentrations of malonic acid and [Ce(III]. These simulation studies show steady state, periodic and non-periodic regions. These studies have been presented as two variable bifurcation phase diagrams. We also have observed the bursting phenomenon under different set of constraints. We have given much importance on computer simulation work but not included the experimental methods in this paper.

  7. High Performance Speed Sensorless Control of Three-Phase Induction Motor Based on Cloud Computing

    Directory of Open Access Journals (Sweden)

    Z. M. Salem

    2012-10-01

    Full Text Available Induction motor is a cast of alternating current motor where charge endures allotted to the rotor close-at-hand deputation of conductive charge. These motors are broadly applied in industrial claim due to they are arduous along with adhere no contacts. The speed controller of deltoid phase induction motor is applied to alleviate the aberration of speed. The central constructivist of this paper is to accrue the performance of speed sensorless control of three phase induction motor. To increase its performance, this paper presents a modified method for speed controller of an indirect vector-controlled induction motor drive using cloud computing technique. Our methodology depends on speed sensorless scheme to obtain the speed signal feedback; the speed estimator is based on model reference adaptive control that uses the stator current and rotor flux as state variables for estimating the speed. In this method, the stator current error is represented as a function of first degree of the estimated speed error. An analysis and simulation of the tried algorithm is birthed and applied easing a TMS320C31 floating-point notational alert Processor. And accumulate the action of the three phase induction motor we conceived our appraisals affixed to the accountant based on cloud computing tactics. This intelligent policy uses the guidelines of the speed controller efficiently. Simulation and experimental results depicted that the motor speed is decelerated articulately to destine its illusion apprise without above and inferior smack and with about zero steady state error. The apprised accelerate alert and its dispatching buoy amassed off line from burlesque. After effects display an advantageous affinity among the accounted speed alert and it's dispatching allocated as well as aped speed flares

  8. Central control of circadian phase in arousal-promoting neurons.

    Directory of Open Access Journals (Sweden)

    Carrie E Mahoney

    Full Text Available Cells of the dorsomedial/lateral hypothalamus (DMH/LH that produce hypocretin (HCRT promote arousal in part by activation of cells of the locus coeruleus (LC which express tyrosine hydroxylase (TH. The suprachiasmatic nucleus (SCN drives endogenous daily rhythms, including those of sleep and wakefulness. These circadian oscillations are generated by a transcriptional-translational feedback loop in which the Period (Per genes constitute critical components. This cell-autonomous molecular clock operates not only within the SCN but also in neurons of other brain regions. However, the phenotype of such neurons and the nature of the phase controlling signal from the pacemaker are largely unknown. We used dual fluorescent in situ hybridization to assess clock function in vasopressin, HCRT and TH cells of the SCN, DMH/LH and LC, respectively, of male Syrian hamsters. In the first experiment, we found that Per1 expression in HCRT and TH oscillated in animals held in constant darkness with a peak phase that lagged that in AVP cells of the SCN by several hours. In the second experiment, hamsters induced to split their locomotor rhythms by exposure to constant light had asymmetric Per1 expression within cells of the middle SCN at 6 h before activity onset (AO and in HCRT cells 9 h before and at AO. We did not observe evidence of lateralization of Per1 expression in the LC. We conclude that the SCN communicates circadian phase to HCRT cells via lateralized neural projections, and suggests that Per1 expression in the LC may be regulated by signals of a global or bilateral nature.

  9. Phase analysis in single-chain variable fragment production by recombinant Pichia pastoris based on proteomics combined with multivariate statistics.

    Science.gov (United States)

    Fujiki, Yuya; Kumada, Yoichi; Kishimoto, Michimasa

    2015-08-01

    The proteomics technique, which consists of two-dimensional gel electrophoresis (2-DE), peptide mass fingerprinting (PMF), gel image analysis, and multivariate statistics, was applied to the phase analysis of a fed-batch culture for the production of a single-chain variable fragment (scFv) of an anti-C-reactive protein (CRP) antibody by Pichia pastoris. The time courses of the fed-batch culture were separated into three distinct phases: the growth phase of the batch process, the growth phase of the fed-batch process, and the production phase of the fed-batch process. Multivariate statistical analysis using 2-DE gel image analysis data clearly showed the change in the culture phase and provided information concerning the protein expression, which suggested a metabolic change related to cell growth and production during the fed-batch culture. Furthermore, specific proteins, such as alcohol oxidase, which is strongly related to scFv expression, and proteinase A, which could biodegrade scFv in the latter phases of production, were identified via the PMF method. The proteomics technique provided valuable information about the effect of the methanol concentration on scFv production.

  10. Harmonics Phase Shifter for a Three-Phase System with Voltage Control by Integral-Cycle Triggering Mode of Thyristors

    Directory of Open Access Journals (Sweden)

    I. Badran

    2008-01-01

    Full Text Available n integral-cycle triggering mode of voltage control, subharmonic as well as higher order harmonic components are generated in the load voltage waveforms of a three-phase system. These harmonic components are found to be unbalanced in phase displacement. The correction of the unbalanced phase displacement angles of a particular subharmonic or higher order harmonic for this type of triggering is investigated to solve the limitation of use of this important type of control as a drive and many other industrial applications. In this research a new phase shifting technique is proposed to correct the unbalanced phase displacement angles in the three-phase system. This technique depends on shifting the waveforms of either phase B or phase C or both by multiples of 2π. A microprocessor-based harmonic phase shifter is designed and tested with three-phase resistive and induction motor loads. It is found that there is a well agreement between the theoretical and experimental results and it is believed that the major problem of harmonics phase unbalances associated with the integral-cycle triggering mode of thyristors when used with three-phase circuits have been solved in the present research.

  11. Controlled topological transitions in thin film phase separation

    CERN Document Server

    Hennessy, Matthew G; Goriely, Alain; Münch, Andreas; Wagner, Barbara

    2014-01-01

    In this paper the evolution of a binary mixture in a thin-film geometry with a wall at the top and bottom is considered. By bringing the mixture into its miscibility gap so that no spinodal decomposition occurs in the bulk, a slight energetic bias of the walls towards each one of the constituents ensures the nucleation of thin boundary layers that grow until the constituents have moved into one of the two layers. These layers are separated by an interfacial region where the composition changes rapidly. Conditions that ensure the separation into two layers with a thin interfacial region are investigated based on a phase-field model. Using matched asymptotic expansions a corresponding sharp-interface problem for the location of the interface is established. It is then argued that this newly created two-layer system is not at its energetic minimum but destabilizes into a controlled self-replicating pattern of trapezoidal vertical stripes by minimizing the interfacial energy between the phases while conserving th...

  12. Controlled Topological Transitions in Thin-Film Phase Separation

    KAUST Repository

    Hennessy, Matthew G.

    2015-01-01

    © 2015 Society for Industrial and Applied Mathematics. In this paper the evolution of a binary mixture in a thin-film geometry with a wall at the top and bottom is considered. By bringing the mixture into its miscibility gap so that no spinodal decomposition occurs in the bulk, a slight energetic bias of the walls toward each one of the constituents ensures the nucleation of thin boundary layers that grow until the constituents have moved into one of the two layers. These layers are separated by an interfacial region where the composition changes rapidly. Conditions that ensure the separation into two layers with a thin interfacial region are investigated based on a phase-field model. Using matched asymptotic expansions a corresponding sharp-interface problem for the location of the interface is established. It is then argued that this newly created two-layer system is not at its energetic minimum but destabilizes into a controlled self-replicating pattern of trapezoidal vertical stripes by minimizing the interfacial energy between the phases while conserving their area. A quantitative analysis of this mechanism is carried out via a thin-film model for the free interfaces, which is derived asymptotically from the sharp-interface model.

  13. Artificial Error Tuning Based on Design a Novel SISO Fuzzy Backstepping Adaptive Variable Structure Control

    Directory of Open Access Journals (Sweden)

    Samaneh Zahmatkesh

    2013-10-01

    Full Text Available This paper examines single input single output (SISO chattering free variable structure control (VSC which controller coefficient is on-line tuned by fuzzy backstepping algorithm to control of continuum robot manipulator. Variable structure methodology is selected as a framework to construct the control law and address the stability and robustness of the close loop system based on Lyapunove formulation. The main goal is to guarantee acceptable error result and adjust the trajectory following. The proposed approach effectively combines the design technique from variable structure controller is based on Lyapunov and modified Proportional plus Derivative (P+D fuzzy estimator to estimate the nonlinearity of undefined system dynamic in backstepping controller. The input represents the function between variable structure function, error and the modified rate of error. The outputs represent joint torque, respectively. The fuzzy backstepping methodology is on-line tune the variable structure function based on adaptive methodology. The performance of the SISO VSC based on-line tuned by fuzzy backstepping algorithm (FBSAVSC is validated through comparison with VSC. Simulation results signify good performance of trajectory in presence of uncertainty joint torque load.

  14. PI controller relay auto-tuning using delay and phase margin in PMSM drives

    Institute of Scientific and Technical Information of China (English)

    Wang Lina; Xiao Kun; Liliana de Lillo; Lee Empringham; Pat Wheeler

    2014-01-01

    This paper presents an auto-tuning method for a proportion plus integral (PI) controller for permanent magnet synchronous motor (PMSM) drives, which is supposed to be embedded in electro-mechanical actuator (EMA) control module in aircraft. The method, based on a relay feed-back with variable delay time, explores different critical points of the system frequency response. The Nyquist points of the plant can then be derived from the delay time and filter time constant. The coefficients of the PI controller can then be obtained by calculation while shifting the Nyquist point to a specific position to obtain the required phase margin. The major advantage of the auto-tuning method is that it can provide a series of tuning results for different system bandwidths and damping ratios, corresponding to the specification for delay time and phase margin. Simulation and experimental results for the PMSM controller verify the performance of both the current loop and the speed loop auto-tuning.

  15. PI controller relay auto-tuning using delay and phase margin in PMSM drives

    Directory of Open Access Journals (Sweden)

    Wang Lina

    2014-12-01

    Full Text Available This paper presents an auto-tuning method for a proportion plus integral (PI controller for permanent magnet synchronous motor (PMSM drives, which is supposed to be embedded in electro-mechanical actuator (EMA control module in aircraft. The method, based on a relay feedback with variable delay time, explores different critical points of the system frequency response. The Nyquist points of the plant can then be derived from the delay time and filter time constant. The coefficients of the PI controller can then be obtained by calculation while shifting the Nyquist point to a specific position to obtain the required phase margin. The major advantage of the auto-tuning method is that it can provide a series of tuning results for different system bandwidths and damping ratios, corresponding to the specification for delay time and phase margin. Simulation and experimental results for the PMSM controller verify the performance of both the current loop and the speed loop auto-tuning.

  16. An electronic flow control system for a variable-rate tree sprayer

    Science.gov (United States)

    Precise modulation of nozzle flow rates is a critical measure to achieve variable-rate spray applications. An electronic flow rate control system accommodating with microprocessors and pulse width modulation (PWM) controlled solenoid valves was designed to manipulate the output of spray nozzles inde...

  17. Exact controllability of the Euler-Bernoulli plate with variable coefficients and simply supported boundary condition

    Directory of Open Access Journals (Sweden)

    Fengyan Yang

    2016-09-01

    Full Text Available This article studies the exact controllability of an Euler-Bernoulli plate equation with variable coefficients, subject to the simply supported boundary condition. By the Riemannian geometry approach, the duality method, the multiplier technique, and the compactness-uniqueness argument, we establish the corresponding observability inequality and obtain the exact controllability results.

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

    Directory of Open Access Journals (Sweden)

    A. J. Arbi

    2008-03-01

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

  19. Variable structure control with sliding mode prediction for discrete-time nonlinear systems

    Institute of Scientific and Technical Information of China (English)

    Lingfei XIAO; Hongye SU; Xiaoyu ZHANG; Jian CHU

    2006-01-01

    A new variable structure control algorithm based on sliding mode prediction for a class of discrete-time nonlinear systems is presented. By employing a special model to predict future sliding mode value, and combining feedback correction and receding horizon optimization methods which are extensively applied on predictive control strategy, a discrete-time variable structure control law is constructed. The closed-loop systems are proved to have robustness to uncertainties with unspecified boundaries. Numerical simulation and pendulum experiment results illustrate that the closed-loop systems possess desired performance, such as strong robustness, fast convergence and chattering elimination.

  20. Wind Turbine Generator Modeling and Simulation Where Rotational Speed is the Controlled Variable

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Blaabjerg, Frede; Boldea, Ion

    2004-01-01

    the interaction between a wind turbine and the power system. The model is intended to simulate the behaviour of the wind turbine using induction generators both during normal operation. Sample simulation results for two induction generators (2/0.5 MW) validate the fundamental issues....... for application in variable speed wind turbines. The usual strategy is to control the power or the torque acting on the wind turbine shafts. This paper presents an alternative control strategy, where the rotational speed is the controlled variable. The paper describes a model, which is being developed to simulate...

  1. Variable structure control for MRAC systems with perturbations in input and output channels

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A design scheme of variable structure model reference control systems using only input and output measurements is presented for the systems with unmodeled dynamics and disturbances in input and output channels. The modeled part of the systems has relative degree greater than one and unknown upper bound of degree. By introducing some auxiliary signals and normalized signals with memory functions and appropriate choice of controller parameters, the developed variable structure controller guarantees the global stability of the closed-loop system and the arbitrarily small tracking error.

  2. The Joint Control of Variable Speed and On-Ramp Metering for Urban Expressway

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The traffic performance of urban expressway is subject to non-recurring and recurring events, which may cause heavy congestion and vehicles long queuing on ramps. The low performance may bring more traffic delay to the whole network of urban road. This paper presents a new method, the joint control of variable speed control and on-ramp metering, which attempts to improve the level of traffic operations on urban expressway. By analyzing traffic flow on urban expressway, an optimum control strategy of variable speed and on-ramp metering is established in the paper.``

  3. Development of Linearizing Feedback Control with a Variable Structure Observer for Continuous Stirred Tank Reactors

    Institute of Scientific and Technical Information of China (English)

    Bachir Daaou; Abdellah Mansouri; Mohamed Bouhamida; Mohammed Chenafa

    2012-01-01

    This paper deals with the design of an observer-based nonlinear control for continuous stirred tank reactors (CSTR). A variable structure observer is constructed to estimate the whole process state variables. This observer is basically the conventional Luenberger observer with an additional switching term used to guarantee the robustness against modeling errors. The observer is coupled with a nonlinear controller, designed based on input-output linearization for controlling the reactor temperature. The asymptotical stability of the closed-loop system is shown by the Lyapunov stability theorem. Finally, computer simulations are developed for showing the performance of the proposed approach.

  4. Liquid phase sintered SiC. Processing and transformation controlled microstructure tailoring

    Directory of Open Access Journals (Sweden)

    V.A. Izhevskyi

    2000-10-01

    Full Text Available Microstructure development and phase formation processes during sintering of silicon carbide based materials with AlN-Y2O3, AlN-Yb2O3, and AlN-La2O3 sintering additives were investigated. Densification of the materials occurred by liquid-phase sintering mechanism. Proportion of alpha- and beta-SiC powders in the initial mixtures was a variable parameter, while the molar ratio of AlN/RE2O3, and the total amount of additives (10 vol. % were kept constant. Shrinkage behavior during sintering in interrelation with the starting composition of the material and the sintering atmosphere was investigated by high temperature dilatometry. Kinetics of b-SiC to a-SiC phase transformation during post-sintering heat treatment at temperatures 1900-1950 °C was studied, the degree of phase transformation being determined by quantitative x-ray analysis using internal standard technique. Evolution of microstructure resulting from beta-SiC to alpha-SiC transformation was followed up by scanning electron microscopy on polished and chemically etched samples. Transformation-controlled grain growth mechanism similar to the one observed for silicon nitride based ceramics was established. Possibility of in-situ platelet reinforced dense SiC-based ceramics fabrication with improved mechanical properties by means of sintering was shown.

  5. Design of variable structure controller for uncertain time-delay singular system

    Institute of Scientific and Technical Information of China (English)

    GUO Ji-feng; GAO Cun-chen

    2009-01-01

    To study the approximation theory of real sliding mode and the design of variable structure controller for time.invariant linear uncertain time-delay singular system,the approximation theory of real sliding mode was developed to provide foundation for obtaining sliding mode by equivalent control,and switching functions with integral dynamic compensators and variable structure controllers were designed respectively under two circum-stances that the system without uncertain part was stabilized by delay-dependent and delay-independent linear stale feedback.The design guarantees the asymptotical stablity of switching manifolds,and the variable struc-ture controllers can.force solution trajectory of the system to arrive at the switching manifolds in limited time.A numerical example is given to demonstrate the feasibility and simplicity of the design method.

  6. Taking purpose into account in experimental psychology: testing for controlled variables.

    Science.gov (United States)

    Marken, Richard S

    2013-02-01

    Experimental research in psychology is based on a causal model--the General Linear Model (GLM)--that assumes behavior has causes but not purposes. Powers (1978) used a control theory analysis to show that the results of psychological experiments based on such a model can be misleading if the organisms being studied are purposeful (control) systems. In the same paper, Powers presented evidence that organisms are such systems. Nevertheless, psychologists continue to use methods that ignore purpose because the behavior in most experiments appears to be non-purposeful (a caused result of variations in the independent variable). The experiments described in this paper show how purposeful behavior can appear to be caused by the independent variable when an organism's purposes are ignored. The results show how taking purpose into account using the control theory-based "Test for the Controlled Variable" can provide a productive new methodological direction for experimental research in psychology.

  7. Use of variable weighting to eliminate numerical diffusion in two-dimensional two-phase flow in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Lasseter, T.J.; Karakas, M.

    1982-01-01

    A simple numerical method has been developed that largely eliminates numerical diffusion errors associated with saturation discontinuities or shocks for two-phase flow in one and two dimensions. The important aspect of the approach is the computation of a variable weighting factor for the interface fractional flow between grid blocks. The approach appears to be generalizable to the multicomponent, multidimensional case including gravity and capilarity. 5 refs.

  8. Design of Neural Network Variable Structure Reentry Control System for Reusable Launch Vehicle

    Institute of Scientific and Technical Information of China (English)

    HU Wei-jun; ZHOU Jun

    2008-01-01

    A flight control system is designed for a reusable launch vehicle with aerodynamic control surfaces and reaction control system based on a variable-structure control and neural network theory. The control problems of coupling among the channels and the uncertainty of model parameters are solved by using the method. High precise and robust tracking of required attitude angles can be achieved in complicated air space. A mathematical model of reusable launch vehicle is pre-sented first, and then a controller of flight system is presented. Base on the mathematical model, the controller is divided into two parts: variable-structure controller and neural network module which is used to modify the parameters of con-troller. This control system decouples the lateral/directional tunnels well with a neural network sliding mode controller and provides a robust and de-coupled tracking for mission angle profiles. After this a control allocation algorithm is employed to allocate the torque moments to aerodynamic control surfaces and thrusters. The final simulation shows that the control system has a good accurate, robust and de-coupled tracking performance. The stable state error is less than 1°, and the overshoot is less than 5%.

  9. Decentralized & Adaptive Load-Frequency Control Scheme of Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Hoseinzadeh, Bakhtyar; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2014-01-01

    In power systems with high penetration of Wind Power (WP), transferring a part of Load Frequency Control (LFC) burden to variable speed Wind Turbines (WTs) is inevitable. The conventional LFC schemes merely rely on frequency information and since frequency is a common variable throughout the netw......In power systems with high penetration of Wind Power (WP), transferring a part of Load Frequency Control (LFC) burden to variable speed Wind Turbines (WTs) is inevitable. The conventional LFC schemes merely rely on frequency information and since frequency is a common variable throughout...... the network, the contribution share of faraway and close WTs in the LFC plan is same, whereas there may be sufficient spinning reserve available in the local WTs close to the event location. This paper employs the initial voltage drop at the moment of perturbation to assess the proximity to the failure point...

  10. Sequential Adaptive RBF-Fuzzy Variable Structure Control Applied to Robotics Systems

    Directory of Open Access Journals (Sweden)

    Mohammed Salem

    2014-08-01

    Full Text Available In this paper, we present a combination of sequential trained radial basis function networks and fuzzy techniques to enhance the variable structure controllers dedicated to robotics systems. In this aim, four RBFs networks were used to estimate the model based part parameters (Inertia, Centrifugal and Coriolis, Gravity and Friction matrices of a variable structure controller so to respond to model variation and disturbances, a sequential online training algorithm based on Growing-Pruning "GAP" strategy and Kalman filter was implemented. To eliminate the chattering effect, the corrective control of the VS control was computed by a fuzzy controller. Simulations are carried out to control three degrees of freedom SCARA robot manipulator where the obtained results show good disturbance rejection and chattering elimination.

  11. Semi-active variable stiffness vibration control of vehicle seat suspension using an MR elastomer isolator

    Science.gov (United States)

    Du, Haiping; Li, Weihua; Zhang, Nong

    2011-10-01

    This paper presents a study on continuously variable stiffness control of vehicle seat suspension using a magnetorheological elastomer (MRE) isolator. A concept design for an MRE isolator is proposed in the paper and its behavior is experimentally evaluated. An integrated seat suspension model, which includes a quarter-car suspension and a seat suspension with a driver body model, is used to design a sub-optimal H_{\\infty } controller for an active isolator. The desired control force generated by this active isolator is then emulated by the MRE isolator through its continuously variable stiffness property when the actuating condition is met. The vibration control effect of the MRE isolator is evaluated in terms of driver body acceleration responses under both bump and random road conditions. The results show that the proposed control strategy achieves better vibration reduction performance than conventional on-off control.

  12. Method and apparatus for smart battery charging including a plurality of controllers each monitoring input variables

    Science.gov (United States)

    Hammerstrom, Donald J.

    2013-10-15

    A method for managing the charging and discharging of batteries wherein at least one battery is connected to a battery charger, the battery charger is connected to a power supply. A plurality of controllers in communication with one and another are provided, each of the controllers monitoring a subset of input variables. A set of charging constraints may then generated for each controller as a function of the subset of input variables. A set of objectives for each controller may also be generated. A preferred charge rate for each controller is generated as a function of either the set of objectives, the charging constraints, or both, using an algorithm that accounts for each of the preferred charge rates for each of the controllers and/or that does not violate any of the charging constraints. A current flow between the battery and the battery charger is then provided at the actual charge rate.

  13. Phase change thermal control materials, method and apparatus

    Science.gov (United States)

    Buckley, Theresa M. (Inventor)

    2001-01-01

    An apparatus and method for metabolic cooling and insulation of a user in a cold environment. In its preferred embodiment the apparatus is a highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The apparatus can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The apparatus may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the apparatus also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  14. Variable Admittance Control Based on Fuzzy Reinforcement Learning for Minimally Invasive Surgery Manipulator

    OpenAIRE

    Du, Zhijiang; Wang, Wei; Yan, Zhiyuan; Dong, Wei; Wang, Weidong

    2017-01-01

    In order to get natural and intuitive physical interaction in the pose adjustment of the minimally invasive surgery manipulator, a hybrid variable admittance model based on Fuzzy Sarsa(?)-learning is proposed in this paper. The proposed model provides continuous variable virtual damping to the admittance controller to respond to human intentions, and it effectively enhances the comfort level during the task execution by modifying the generated virtual damping dynamically. A fuzzy partition de...

  15. Resistance Torque Based Variable Duty-Cycle Control Method for a Stage II Compressor

    Science.gov (United States)

    Zhong, Meipeng; Zheng, Shuiying

    2017-07-01

    The resistance torque of a piston stage II compressor generates strenuous fluctuations in a rotational period, and this can lead to negative influences on the working performance of the compressor. To restrain the strenuous fluctuations in the piston stage II compressor, a variable duty-cycle control method based on the resistance torque is proposed. A dynamic model of a stage II compressor is set up, and the resistance torque and other characteristic parameters are acquired as the control targets. Then, a variable duty-cycle control method is applied to track the resistance torque, thereby improving the working performance of the compressor. Simulated results show that the compressor, driven by the proposed method, requires lower current, while the rotating speed and the output torque remain comparable to the traditional variable-frequency control methods. A variable duty-cycle control system is developed, and the experimental results prove that the proposed method can help reduce the specific power, input power, and working noise of the compressor to 0.97 kW·m-3·min-1, 0.09 kW and 3.10 dB, respectively, under the same conditions of discharge pressure of 2.00 MPa and a discharge volume of 0.095 m3/min. The proposed variable duty-cycle control method tracks the resistance torque dynamically, and improves the working performance of a Stage II Compressor. The proposed variable duty-cycle control method can be applied to other compressors, and can provide theoretical guidance for the compressor.

  16. Control and Optimization of a Variable-Pitch Quadrotor with Minimum Power Consumption

    Directory of Open Access Journals (Sweden)

    Shouzhao Sheng

    2016-03-01

    Full Text Available Recently, there has been a rapid growth of interest in quadrotors with electric variable-pitch propellers. The control and optimization of such propellers are important factors for improving the flight performance of the vehicles. Therefore, the steady-state identification method to estimate the parameters of the mathematical model of the electric variable-pitch propeller is developed. The steady-state control and optimization scheme with minimum power consumption and the adaptive compensation scheme for the variable-pitch propeller are then proposed, based on which the response performance of the lift force produced by the variable-pitch propeller can be greatly improved by using a cascade compensation scheme. Furthermore, the direct lift-based flight control strategy is presented, which can significantly contribute to the improvement of the flight performance, precisely because the roll, pitch, yaw and vertical channels of the variable-pitch quadrotor are approximately linearized and completely decoupled from each other in this case. The experimental results demonstrate that both the endurance performance and the positioning accuracy of the variable-pitch quadrotor are improved simultaneously by using the proposed method with minimum power consumption.

  17. Variable tension control for discontinuous tape winding of composites based on constant extension ratio

    Science.gov (United States)

    Shi, Yaoyao; Yan, Long; He, Xiaodong

    2012-09-01

    Discontinuous tape winding, which has obvious advantages in large extension ratio winding, is widely used in the molding of composites. Therefore, the research on technological parameters becomes the focus of many scholars. However, how to accomplish the variable tension control is usually not fully considered. Accordingly, the constant extension ratio and the smoothness of winding process cannot be ensured. Aiming at the problem of tension control, this paper first gives a comparatively deep research on the control method and the interaction mechanism of tension, extension ratio, automatic lap and automatic rectification. Then, according to the winding process features, the mechanical device and the mathematical model of tension control system are established respectively. With regard to the characteristics of PID controller and fuzzy controller, the fuzzy self-tuning PID controller is designed. As a result, the variable tension control is realized during the winding and lapping process, and the constant extension ratio is guaranteed. Finally, a sample application is presented for demonstration. By presenting the variable tension control techniques for discontinuous tape winding, the constant extension ratio of tapes is achieved, the consecution and the automation degree of winding process is improved as well. Thus, the quality of wound products is guaranteed.

  18. A multi-harmonic amplitude and relative-phase controller for active sound quality control

    Science.gov (United States)

    Mosquera-Sánchez, Jaime A.; de Oliveira, Leopoldo P. R.

    2014-04-01

    Current active sound quality control systems aim at dealing with the amplitude level of the primary disturbance, e.g. sound pressure, forces, velocities and/or accelerations, which implicitly leads to Loudness control, regardless of the spectral structure of the disturbance. As far as multi-harmonic disturbances are concerned, auditory Roughness, arguably the most related psychoacoustic metric with rumbling perception in passenger cars, can be tackled not merely by dealing with magnitudes but also with the relative-phase of the narrowband components. This paper presents an adaptive control scheme conceived for dealing with multi-harmonic disturbances, which features the independent amplitude and/or relative-phase control of the input periodic components and an improved robustness to impulsive events. The adaptive control scheme is based on a frequency-domain delayless implementation of the complex-domain, least mean squares algorithm, whereof its convergence process is improved by using a forgetting factor. The control capabilities are evaluated numerically for single- and multiple-harmonic disturbances, including realistic internal combustion engine sound contaminated with noise and by impulsive events. By using long transfer paths obtained from a real vehicle mock-up, sound pressure level reductions of 39 dBSPL and the ability to displacing the relative-phase of a number of narrowband components between [-π,π] are accomplished by the proposed control scheme. The assessment of the results by using Zwicker-Loudness and auditory Roughness models shows that the proposed adaptive algorithm is able to accomplish and stably preserve various sound quality targets, after completion of the robust convergence procedure, regardless of impulsive events that can occur during the system operation.

  19. Rotation Modes Stability Analysis and Phase Compensation for Magnetically Suspended Flywheel Systems with Cross Feedback Controller and Time Delay

    Directory of Open Access Journals (Sweden)

    Yuan Ren

    2016-01-01

    Full Text Available This paper analyzes the effects of time delay on the stability of the rotation modes for the magnetically suspended flywheel (MSFW with strong gyroscopic effects. A multi-input multioutput system is converted into a single-input single-output control system with complex coefficient by variable reconstruction, and the stability equivalence of the systems before and after variable reconstruction is proven. For the rotation modes, the stability limits and corresponding vibration frequencies are found as a function of nondimensional magnetic stiffness and damping and nondimensional parameters of rotor speed and time delay. Additionally, the relationship between cross feedback control system stability and time delay is investigated. And an effective phase compensation method based on cross-channel is further presented. Simulation and experimental results are presented to demonstrate the correctness of the stability analysis method and the superiority of the phase compensation strategy.

  20. Coherent phase control of internal conversion in pyrazine

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Robert J., E-mail: rjgordon@uic.edu; Singha, Sima; Zhao, Youbo [Department of Chemistry (m/c 111), University of Illinois at Chicago, Chicago, Illinois 60680-7061 (United States); Hu, Zhan [Institute of Atomic and Molecular Physics, Jilin University, Changchun 130021 (China); Seideman, Tamar [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (United States); Sukharev, Maxim [Science and Mathematics Faculty, College of Letters and Sciences, Arizona State University, Mesa, Arizona 85212 (United States)

    2015-04-14

    Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the S{sub 2} and S{sub 1} states. Very different, non-classical behavior was observed when a genetic algorithm (GA) employing phase-only modulation was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T < 1.5 ps) and late (T > 1.5 ps) target times. In the former case, the ion signal was largely suppressed for t < T, while for t ≫ T, the ion signal produced by the GA-optimized pulse and a transform limited (TL) pulse coalesced. In contrast, for T > 1.5 ps, the ion growth curve followed the classical rate equations for t < T, while for t ≫ T, the quantum yield for the GA-optimized pulse was much smaller than for a TL pulse. We interpret the first type of behavior as an indication that the wave packet produced by the pump laser is localized in a region of the S{sub 2} potential energy surface where the vertical ionization energy exceeds the probe photon energy, whereas the second type of behavior may be described by a reduced absorption cross section for S{sub 0} → S{sub 2} followed by incoherent decay of the excited molecules. Amplitude modulation observed in the spectrum of the shaped pulse may have contributed to the control mechanism, although this possibility is mitigated by the very small focal volume of the probe laser.

  1. Coherent phase control of internal conversion in pyrazine

    Science.gov (United States)

    Gordon, Robert J.; Hu, Zhan; Seideman, Tamar; Singha, Sima; Sukharev, Maxim; Zhao, Youbo

    2015-04-01

    Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the S2 and S1 states. Very different, non-classical behavior was observed when a genetic algorithm (GA) employing phase-only modulation was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T 1.5 ps) target times. In the former case, the ion signal was largely suppressed for t 1.5 ps, the ion growth curve followed the classical rate equations for t quantum yield for the GA-optimized pulse was much smaller than for a TL pulse. We interpret the first type of behavior as an indication that the wave packet produced by the pump laser is localized in a region of the S2 potential energy surface where the vertical ionization energy exceeds the probe photon energy, whereas the second type of behavior may be described by a reduced absorption cross section for S0 → S2 followed by incoherent decay of the excited molecules. Amplitude modulation observed in the spectrum of the shaped pulse may have contributed to the control mechanism, although this possibility is mitigated by the very small focal volume of the probe laser.

  2. A V/f= cte Control Drive for Permanent Capacitor Single-Phase Induction Motor

    Directory of Open Access Journals (Sweden)

    Pedram Shahriari Nasab

    2013-01-01

    Full Text Available Poor performance of the convectional household induction motors which used in home appliances such as refrigerator, cooler, laundry, washing machines, fans, hand-held power tools, and automotive window lift is generally caused by two main reasons. Firstly, they have high starting current which causes significant voltage drop, and secondly, they operate in a single speed mode and not in variable speed. In many home appliances, traditionally a discrete speed control method is used by changing the number of the poles. A proper solution for these problems can be achieved by using control drive systems. In this paper, a simple scalar control method is applied to control the speed of a permanent capacitor single phase induction motor (PCSPIM. The philosophy of this method is on the basis of simultaneous system’s frequency and voltage control on the machines terminals subject to V/f=cte. Simulation and practical implementation results clearly show the effectiveness of the simple V/f =cte speed control method for home appliances.

  3. A Novel Sliding Mode Variable Structure Controller Based on a Genetic Algorithm

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel control method has been proposed by using the genetic algorithm ( GA ) for nonlinear and complex plants. The proposed control strategy is based on a variable structure control, it overcomes the defects of other adaptive methods such as strong dependence to the system. A GA is used to learn to optimally select integral coefficient C. Simulation results verified the effectiveness of the controller. For position control of Direct Current (DC) motor in practice, this method has good performance and strong robustness, and both dynamic and steady performances were improved.

  4. Modelling and control of variable speed wind turbines for power system studies

    DEFF Research Database (Denmark)

    Michalke, Gabriele; Hansen, Anca Daniela

    2010-01-01

    Modern wind turbines are predominantly variable speed wind turbines with power electronic interface. Emphasis in this paper is therefore on the modelling and control issues of these wind turbine concepts and especially on their impact on the power system. The models and control are developed...... and implemented in the power system simulation tool DIgSILENT. Important issues like the fault ride-through and grid support capabilities of these wind turbine concepts are addressed. The paper reveals that advanced control of variable speed wind turbines can improve power system stability. Finally......, it will be shown in the paper that wind parks consisting of variable speed wind turbines can help nearby connected fixed speed wind turbines to ride-through grid faults. Copyright © 2009 John Wiley & Sons, Ltd....

  5. Variable speed wind turbine generator system with current controlled voltage source inverter

    Energy Technology Data Exchange (ETDEWEB)

    Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

    2011-07-15

    highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

  6. Quantifying coordination and coordination variability in backward versus forward running: Implications for control of motion.

    Science.gov (United States)

    Mehdizadeh, Sina; Arshi, Ahmed Reza; Davids, Keith

    2015-07-01

    The aims of this study were to compare coordination and coordination variability in backward and forward running and to investigate the effects of speed on coordination variability in both backward and forward running. Fifteen healthy male participants took part in this study to run forwards and backwards on a treadmill at 80%, 100% and 120% of their preferred running speeds. The coordinate data of passive reflective markers attached to body segments were recorded using motion capture systems. Coordination of shank-foot and thigh-shank couplings in sagittal plane was quantified using the continuous relative phase method. Coordination variability was calculated as the standard deviation of a coordination pattern over 50 strides. Cross-correlation coefficients and associated phase shifts were determined to quantify similarity in coordination patterns between forward and backward running. Our results demonstrated that the coordination pattern in a gait cycle of backward running was in reverse to that of forward running at all speeds implying that the same neural circuitry is responsible for regulating both forward and backward running gaits. In addition, results demonstrated that there was an average of approximately 11% phase shift between the coordination patterns of backward and forward running which indicates that a single underlying mechanism might be responsible for generating motor patterns in both forward and backward running. Finally, backward running had significantly higher magnitude of coordination variability compared to forward running, signifying that more degrees of freedom were involved in backward running. Speed however, did not affect coordination variability in either task. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Perceived parental psychological control and eating-disordered symptoms: maladaptive perfectionism as a possible intervening variable.

    Science.gov (United States)

    Soenens, Bart; Vansteenkiste, Maarten; Vandereycken, Walter; Luyten, Patrick; Sierens, Eline; Goossens, Luc

    2008-02-01

    Recent developmental theorizing conceptualizes perfectionism as a mediator of the relation between intrusive parenting and psychopathology. Research addressing this hypothesis in relation to eating disorders (EDs), however, is lacking. This case-control study (a) examined mean-level differences between ED patients and normal controls in psychologically controlling parenting and perfectionism and (b) addressed the intervening role of perfectionism in associations between psychological control and ED symptoms, distinguishing between maladaptive and relatively more adaptive types of perfectionism. Hypotheses were examined in a sample of normal controls (N = 85) and a sample of ED patients (N = 60). Findings indicate that ED patients and bulimics in particular show elevated levels of paternal (but not maternal) psychological control and elevated levels of maladaptive perfectionism compared with normal controls. Mediation analyses show that maladaptive perfectionism is a significant intervening variable between parental psychological control and ED symptoms. Directions for future research on controlling parenting, perfectionism, and ED are outlined.

  8. Heating control strategy in fresh air processor matched with variable refrigerant flow air conditioning system

    Energy Technology Data Exchange (ETDEWEB)

    Tu Qiu, E-mail: tuqiuky@163.co [Guangzhou Institute of Energy Conversion, Chinese Academy of Science, Guangzhou 510640 (China) and Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Science, Guangzhou 510640 (China); Mao Shoubo; Feng Yuhai; Guo Defang [Haier Air-Conditioning Electronic Co. Ltd., Qingdao 266510 (China)

    2011-07-15

    Highlights: {yields} A set of fresh air processor matched with VRF AC has been designed. {yields} The heating control model of variable condensation temperature target has been presented {yields} The control strategy can realize reliable running, high control accuracy and energy-saving. {yields} The control model is universal for fresh air processors with different capacities. -- Abstract: The fresh air processor (FAP), matched with the variable refrigerant flow air conditioning system (VRF AC), has been developed. Two control methods were adopted to control the system running and air outlet temperature, contrastively. The first method is that the running frequency in heating mode is adjusted in terms of the ordinary control method of VRF, i.e., constant condensation temperature. The experiment demonstrates the control method is not feasible. For nominal heating under different static pressure and defrosting under 200 Pa static pressure, the system fluctuates frequently. And for high temperature heating, the air outlet temperature far exceeds the target temperature. Furthermore, the control model of variable condensation temperature target has been presented, and the heat transfer correction factor is introduced into the control model. And the control parameters in the model are determined by experiment. The control model is universal for FAPs with different capacities by identifying and choosing the heat transfer correction factor in the control program. For low temperature heating, the method of switching rotation speed of the motor can be adopted to enhance air outlet temperature to 22 {sup o}C. The control strategy can provide guide for the design and application of FAP.

  9. A control strategy for induction motors fed from single phase supply

    DEFF Research Database (Denmark)

    Søndergård, Lars Møller

    1993-01-01

    It is often required that a three-phased asynchronous motor can run at variable speed, which makes it necessary to use a three-phase inverter driven from a DC-source. Today, most inverters are driven from the network using a simple diode bridge and an electrolytic capacitor. The problem with the ......It is often required that a three-phased asynchronous motor can run at variable speed, which makes it necessary to use a three-phase inverter driven from a DC-source. Today, most inverters are driven from the network using a simple diode bridge and an electrolytic capacitor. The problem...

  10. Variable Structure Disturbance Rejection Control for Nonlinear Uncertain Systems with State and Control Delays via Optimal Sliding Mode Surface Approach

    Directory of Open Access Journals (Sweden)

    Jing Lei

    2013-01-01

    Full Text Available The paper considers the problem of variable structure control for nonlinear systems with uncertainty and time delays under persistent disturbance by using the optimal sliding mode surface approach. Through functional transformation, the original time-delay system is transformed into a delay-free one. The approximating sequence method is applied to solve the nonlinear optimal sliding mode surface problem which is reduced to a linear two-point boundary value problem of approximating sequences. The optimal sliding mode surface is obtained from the convergent solutions by solving a Riccati equation, a Sylvester equation, and the state and adjoint vector differential equations of approximating sequences. Then, the variable structure disturbance rejection control is presented by adopting an exponential trending law, where the state and control memory terms are designed to compensate the state and control delays, a feedforward control term is designed to reject the disturbance, and an adjoint compensator is designed to compensate the effects generated by the nonlinearity and the uncertainty. Furthermore, an observer is constructed to make the feedforward term physically realizable, and thus the dynamical observer-based dynamical variable structure disturbance rejection control law is produced. Finally, simulations are demonstrated to verify the effectiveness of the presented controller and the simplicity of the proposed approach.

  11. A novel technology for control of variable speed pumped storage power plant

    Institute of Scientific and Technical Information of China (English)

    Seyed Mohammad Hassan Hosseini; Mohammad Reza Semsar

    2016-01-01

    Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control (DTFC) of a variable speed pumped storage power plant (VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP’s control strategies is studied. At the first, a wind turbine with the capacity 2.2 kW and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts (including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter (2LVSC) and three-level voltage source converter (3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion (THD) and ripple of rotor torque and flux.

  12. DISCRETE VARIABLE STRUCTURE CONTROL OF LINEAR TIME-INVARIANT SYSTEMS WITH TIME DELAY

    Institute of Scientific and Technical Information of China (English)

    蔡国平; 黄金枝

    2002-01-01

    A discrete variable structure control(DVSC) method for the linear time-invariant systems with time delay was presented. The continuous time-delay systems are first transformed into the standard discrete form which contains no time delay by augmenting the state variables. Then the switching surface is determined by using the ideal quasi-sliding mode. As it is difficult for the state trajectory to reach the switching surface exactly, the reaching condition in the form of approach law is used to design the controller. The deduced switching surface and controller contain not only the current step of state feedback but also some former steps of controls. Stability analysis with and without time-delay information is also investigated in this paper. Numerical simulation was carried out to demonstrate the effectiveness and feasibility of the presented control method.

  13. Design of Model Following Variable Structure Controller for Three-axle Vehicle

    Institute of Scientific and Technical Information of China (English)

    管西强; 张建武; 屈求真

    2003-01-01

    An optimal control procedure is developed for the front and rear wheels of a three-axle vehicle moving on a complex typical road based on model following variable structure control strategy. The actual vehicle may be considered as an uncertain system. Cornering stiffness of front and rear wheels and external disturbances are varied in a limited range. The model-following variable structure control method is used to control both front and rear wheels steering operations of the vehicle, so that steering responses of the vehicle follow from those of the reference model. By numerical results obtained from computer simulation, it is demonstrated that the control system model can cope with the effects of parameter perturbations and outside disturbances.

  14. Experimental variables in the synthesis of brookite phase TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bhave, Radhika C. [School of Material Science and Engineering, Clemson University, Clemson, SC 29634 (United States); Lee, Burtrand I. [School of Material Science and Engineering, Clemson University, Clemson, SC 29634 (United States)], E-mail: burt.lee@ces.clemson.edu

    2007-10-15

    Nanocrystalline brookite titanium dioxide particles have been prepared under ambient condition sol process. Titanium tetrachloride was the precursor in water with isopropanol as the co-solvent in hydrochloric acid. The formed gel mass was peptized and crystallized under refluxing condition. The effect of various parameters, such as temperature, time, water to alcohol ratio, and pH of the sol on the phase obtained were investigated. The refluxing temperature of 83 deg. C with the refluxing time of 15 h led to the formation of pure brookite phase as indicated by X-ray diffractometry (XRD). Whereas, lower temperature of 70 deg. C gave a mixture of rutile and anatase phases, and higher temperature of 100 deg. C gave mixture of rutile and brookite phases. Addition of hydroxypropyl cellulose yielded a more uniform particle size along with higher surface area. The water to alcohol ratio had minimal effect, when taken in the ratio of 1:2 or above, on the brookite phase formation.

  15. OUTPUT VARIABLE STRUCTURE CONTROL FOR TIME-INVARIANT LINEAR TIME-DELAY SINGULAR SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Jifeng GUO; Cunchen GAO

    2007-01-01

    Synthesis and design of output variable structure controller for time-invariant linear time-delay singular system are studied. In the case that the system is regular and the system index is one, switching function with integral compensator and variable structure controller are designed, which guarantee that the sliding mode is asymptotically stable and the solution trajectory of the system arrives at the switching manifold in limited time. The design method is applicable to the systems which can be regularized. Finally, a numerical example is given to demonstrate effectiveness and simplicity of the design method.

  16. An LMI-based variable structure control for a class of uncertain singular Markov switched systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An H-infinifty variable structure control is presented for singular Markov switched systems with mismatched norm-bounded uncertainties and mismatched norm-bounded external disturbances.It iS shown that the sliding mode dynamics on the given switching surface is regular,impulse-free,and stochastically stable and satisfies H-infinity performance.A variable structure controller is designed to guarantee that the system trajectory converges to the linear switching surface in some finite time.Finally,a numencal example is solved to show the effectiveness and validness of the theoretical results.

  17. Electromagnetic Design of a New Electrically Controlled Magnetic Variable-Speed Gearing Machine

    Directory of Open Access Journals (Sweden)

    Chunhua Liu

    2014-03-01

    Full Text Available This paper proposes a new electrically controlled magnetic variable-speed gearing (EC-MVSG machine, which is capable of providing controllable gear ratios for hybrid electric vehicle (HEV applications. The key design feature involves the adoption of a magnetic gearing structure and acceptance of the memory machine flux-mnemonic concept. Hence, the proposed machine can not only offer a gear-shifting mechanism for torque and speed transmission, but also provide variable gear ratios for torque and speed variation. The electromagnetic design is studied and discussed. The finite-element method is developed with the hysteresis model to verify the validity of the machine design.

  18. Fuzzy variable impedance control based on stiffness identification for human-robot cooperation

    Science.gov (United States)

    Mao, Dachao; Yang, Wenlong; Du, Zhijiang

    2017-06-01

    This paper presents a dynamic fuzzy variable impedance control algorithm for human-robot cooperation. In order to estimate the intention of human for co-manipulation, a fuzzy inference system is set up to adjust the impedance parameter. Aiming at regulating the output fuzzy universe based on the human arm’s stiffness, an online stiffness identification method is developed. A drag interaction task is conducted on a 5-DOF robot with variable impedance control. Experimental results demonstrate that the proposed algorithm is superior.

  19. An Asynchronous Electric Drive with the Indirect Control of the Output Variables

    Directory of Open Access Journals (Sweden)

    Glazachev Alexander V.

    2017-01-01

    Full Text Available The article gives a mathematical description of an asynchronous motor with a device of indirect control of the electromagnetic torque and the angular velocity of the asynchronous motor in the electric drive that allows to prove on its basis the method of monitoring the output variables of the asynchronous electric motor. The simulation model of an asynchronous motor with a device of indirect control of the output variables of the asynchronous motor and the main results of the study have been given.

  20. Analytical Model of Fixed-Frequency Variable Duty-Cycle Controlled LLC Resonant Converter

    DEFF Research Database (Denmark)

    Shen, Yanfeng; Wang, Huai; Blaabjerg, Frede;

    2016-01-01

    For LLC resonant converters, the fixed-frequency variable duty-cycle control is usually combined with the variable frequency (VF) control to widen the gain range, improve light-load efficiency or suppress the inrush current during start-up. However, both the operation mode and the steady...... is derived, which makes the fast and automatic design optimization possible. The critical characteristics, such as dc voltage gain, peak resonant current, peak capacitor voltage, rms current as well as the constraint conditions for the operation mode are developed and verified with simulation...

  1. A method of variable spacing for controlled plant growth systems in spaceflight and terrestrial agriculture applications

    Science.gov (United States)

    Knox, J.

    1986-01-01

    A higher plant growth system for Controlled Ecological Life Support System (CELSS) applications is described. The system permits independent movement of individual plants during growth. Enclosed within variable geometry growth chambers, the system allocates only the volume required by the growing plants. This variable spacing system maintains isolation between root and shoot environments, providing individual control for optimal growth. The advantages of the system for hydroponic and aeroponic growth chambers are discussed. Two applications are presented: (1) the growth of soybeans in a space station common module, and (2) in a terrestrial city greenhouse.

  2. Characteristics and controls of variability in soil moisture and groundwater in a headwater catchment

    Science.gov (United States)

    McMillan, H. K.; Srinivasan, M. S.

    2015-04-01

    Hydrological processes, including runoff generation, depend on the distribution of water in a catchment, which varies in space and time. This paper presents experimental results from a headwater research catchment in New Zealand, where we made distributed measurements of streamflow, soil moisture and groundwater levels, sampling across a range of aspects, hillslope positions, distances from stream and depths. Our aim was to assess the controls, types and implications of spatial and temporal variability in soil moisture and groundwater tables. We found that temporal variability in soil moisture and water table is strongly controlled by the seasonal cycle in potential evapotranspiration, for both the mean and extremes of their distributions. Groundwater is a larger water storage component than soil moisture, and this general difference increases even more with increasing catchment wetness. The spatial standard deviation of both soil moisture and groundwater is larger in winter than in summer. It peaks during rainfall events due to partial saturation of the catchment, and also rises in spring as different locations dry out at different rates. The most important controls on spatial variability in storage are aspect and distance from the stream. South-facing and near-stream locations have higher water tables and showed soil moisture responses for more events. Typical hydrological models do not explicitly account for aspect, but our results suggest that it is an important factor in hillslope runoff generation. Co-measurement of soil moisture and water table level allowed us to identify relationships between the two. Locations where water tables peaked closer to the surface had consistently wetter soils and higher water tables. These wetter sites were the same across seasons. However, patterns of strong soil moisture responses to summer storms did not correspond to the wetter sites. Total catchment spatial variability is composed of multiple variability sources, and the

  3. Phase behavior of the thermoresponsive polymer Poly(N-isopropyl acrylamide) at variable pressure

    Science.gov (United States)

    Schulte, Alfons; Claude, Kora-Lee; Pinzek, Simon; Müller-Buschbaum, Peter; Papadakis, Christine

    Stimuli-responsive such as Poly(N-isopropyl acrylamide) (PNIPAM) exhibit lower critical solution temperature (LCST) behaviour. At ambient pressure it is associated with the release of water and coil to globule transition of the polymer chains, leading to phase separation. Using turbidimetry we measure the P-T phase diagram over an extended range of pressure (0.1 - 400 MPa) and temperature (-10 - 40 oC). The phase boundary shows an elliptic profile, i.e. the cloud point temperature first increases and then decreases with pressure. This is reflected in the change in Gibbs free energy, isothermal compressibility, and isobaric heat capacity. The role of solvent-solvent interaction and addition of co-solvents is discussed.

  4. Computing variable bounds in the conceptual design phase of guided weapon systems

    NARCIS (Netherlands)

    Weiss, M.; Buco, D.

    2012-01-01

    The performance of guided weapon systems is primarily expressed by the end-of-flight effect, routinely approximated by the miss distance. It is however equally important that certain system variables of interest are kept within given bounds all along the duration of the flight. In this paper, we pro

  5. Computing variable bounds in the conceptual design phase of guided weapon systems

    NARCIS (Netherlands)

    Weiss, M.; Buco, D.

    2012-01-01

    The performance of guided weapon systems is primarily expressed by the end-of-flight effect, routinely approximated by the miss distance. It is however equally important that certain system variables of interest are kept within given bounds all along the duration of the flight. In this paper, we

  6. Sample controlled reaction temperature (SCRT): Controlling the phase composition of silicon nitride obtained by carbothermal reduction

    Energy Technology Data Exchange (ETDEWEB)

    Alcala, M.D.; Criado, J.M.; Real, C. [Instituto de Ciencia de Materiales de Sevilla, c/Americo Vespucio s/n; Isla de La Cartuja, 41092 Sevilla (Spain)

    2002-07-01

    Carbothermal reduction of silica is one of the most common methods of producing Si{sub 3}N{sub 4} powders. The experimental conditions have an important influence on the structure of the final product, especially the balance of {alpha}- to {beta}- Si{sub 3}N{sub 4}. The Sample Controlled Reaction Temperature method describes here has permitted to conclude that the phase composition of the silicon nitride is governed by the partial pressure of CO in the close vicinity of the sample. Moreover, the control of this parameter has an important influence on particle size and morphology of the final product. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  7. PEBB Feedback Control Low Library. Volume 1: Three-Phase Inverter Control Algorithms

    Science.gov (United States)

    1999-01-01

    ship propulsion electrical loads are powered from a common set of prime movers. Presently, the current generation of PEBB-like devices include high-power, fast-switching, high-bandwidth dc-dc converters and dc-ac inverters. This report summarized the algorithms required to control a conventional three-phase inverter. First, implementation issues regarding the Sine-Triangle Pulse-Width-Modulation and Space-Vector Modulation are presented with an emphasis placed on digital realizations. Then, two current control schemes are documented via analysis, design example, and

  8. Attitude Control Considering Variable Input Saturation Limit for a Spacecraft Equipped with Flywheels

    Institute of Scientific and Technical Information of China (English)

    TIAN Lin; XU Shijie

    2012-01-01

    A new attitude controller is proposed for spacecraft whose actuator has variable input saturation limit.There are three identical flywheels orthogonally mounted on board.Each rotor is driven by a brushless DC motor (BLDCM).Models of spacecraft attitude dynamics and flywheel rotor driving motor electromechanics are discussed in detail.The controller design is similar to saturation limit linear assignment.An auxiliary parameter and a boundary coefficient are imported into the controller to guarantee system stability and improve control performance.A time-varying and state-dependent flywheel output torque saturation limit model is established.Stability of the closed-loop control system and asymptotic convergence of system states are proved via Lyapunov methods and LaSalle invarianee principle.Boundedness of the auxiliary parameter ensures that the control objective can be achieved,while the boundary parameter's value makes a balance between system control performance and flywheel utilization efficiency.Compared with existing controllers,the newly developed controller with variable torque saturation limit can bring smoother control and faster system response.Numerical simulations validate the effectiveness of the controller.

  9. Method of using an electric field controlled emulsion phase contactor

    Science.gov (United States)

    Scott, Timothy C.

    1993-01-01

    A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

  10. Indium Growth and Island Height Control on Si Submonolayer Phases

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jizhou [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    lithography (EUVL) have a wave length of 13.4 nm so it can curve on the surface of an sample to make structure as small as the order of 10 nm. however, lithograph usually causes permanent damages to the surface and in many cases the QDs are damaged during the lithograph and therefore result in high percentage of defects. Quantum size effect has attracted more and more interests in surface science due to many of its effects. One of its effects is the height preference in film growing and the resulting possibility of uniformly sized self-assemble nanostructure. The experiment of Pb islands on In 4x1 phase shows that both the height and the width can be controlled by proper growth conditions, which expands the growth dimensions from 1 to 2. This discover leads us to study the In/Pb interface. In Ch.3, we found that the Pb islands growing on In 4x1-Si(111) surface which have uniform height due to QSE and uniform width due to the constriction of In 4x1 lattice have unexpected stability. These islands are stable in even RT, unlike usual nanostructures on Pb/Si surface which are stable only at low temperature. Since similar structures are usually grown at low temperature, this discovery makes the grown structures closer to technological applications. It also shows the unusual of In/Pb interface. Then we studied the In islands grown on Pb-α-√3x√3-Si(111) phase in Ch.4. These islands have fcc structure in the first few layers, and then convert to bct structure. The In fcc islands have sharp height preference due to QSE like Pb islands. However, the preferred height is different (7 layer for Pb on Si 7x7 and 4 layer for Pb on In 4x1), due to the difference of interface. The In islands structure prefers to be bct than fcc with coverage increase. It is quantitatively supported by first-principle calculation. Unexpectedly, the In islands grown on various of In interfaces didn't show QSE effects and phase transition from fcc and bct structures as on the Pb-α interface (Ch.6). In

  11. Enhanced Phase-Shifted Current Control for Harmonic Cancellation in Three-Phase Multiple Adjustable Speed Drive Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Davari, Pooya; Zare, Firuz

    2017-01-01

    A phase-shifted current control can be employed to mitigate certain harmonics induced by the Diode Rectifiers (DR) and Silicon-Controlled Rectifiers (SCR) as the front-ends of multiple parallel Adjustable Speed Drive (ASD) systems. However, the effectiveness of the phase-shifted control relies on......-shifted current control is a cost-effective solution to multiple ASD systems in terms of harmonic cancellation.......A phase-shifted current control can be employed to mitigate certain harmonics induced by the Diode Rectifiers (DR) and Silicon-Controlled Rectifiers (SCR) as the front-ends of multiple parallel Adjustable Speed Drive (ASD) systems. However, the effectiveness of the phase-shifted control relies...... on the loading condition of each drive unit as well as the number of drives in parallel. In order to enhance the harmonic cancellation by means of the phase-shifted current control, the currents drawn by the rectifiers should be maintained almost at the same level. Thus, this paper firstly analyzes the impact...

  12. Design and control of single-phase dynamic voltage restorer

    Indian Academy of Sciences (India)

    AMIT MEENA; SHIRAZUL ISLAM; SANDEEP ANAND; YOGESH SONAWANE; SANJAY TUNGARE

    2017-08-01

    Dynamic voltage restorer (DVR) is a custom power device used in electrical distribution system for power quality improvement. It ensures regulated voltage supply to the sensitive loads, even in case of voltage sag and swell disturbances in the distribution network. It is a series connected device and compensates voltagesag and swell by injecting a voltage with the help of a series transformer. The injection of an appropriate voltage component in the event of a voltage disturbance requires a certain amount of real and reactive power. Conventionally,DVR consists of an energy storage device, which supplies the required power over the limited duration of the sags. Large magnitude and long duration of sags lead to heavy financial investment in energy storage unit. To overcome this limitation, a single-phase back-to-back converter-based DVR is implemented inthis work, which eliminates energy storage requirement. The integration of series and shunt converter makes the DVR capable of bidirectional flow of energy. Therefore, the key advantage of this topology is its capability to compensate for long-term voltage sag and swell. Modelling of the DVR and its controller design is included in this paper. The effectiveness of control schemes, protection schemes and starting sequence of operation of DVR is verified through detailed simulation studies. A scaled down laboratory prototype of DVR is developed. The viability of these schemes is confirmed by the experimental results generated from the laboratory prototype. Various challenges faced during the prototype development and corresponding solutions are also discussed in this paper.

  13. Modeling and control of PMSG-based variable-speed wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Woo; Ko, Hee-Sang [Wind Energy Research Center, Korea Institute of Energy Research, Yuseong-gu Jang-Dong 71-2,305-343 Daejeon (Korea); Kim, Sung-Soo [Chungbuk National University (Korea)

    2010-01-15

    This paper presents a control scheme of a variable-speed wind turbine with a permanent-magnetic synchronous generator (PMSG) and full-scale back-to-back voltage source converter. A comprehensive dynamical model of the PMSG wind turbine and its control scheme is presented. The control scheme comprises both the wind-turbine control itself and the power-converter control. In addition, since the PMSG wind turbine is able to support actively the grid due to its capability to control independently active and reactive power production to the imposed set-values with taking into account its operating state and limits, this paper presents the supervisory reactive power control scheme in order to regulate/contribute the voltage at a remote location. The ability of the control scheme is assessed and discussed by means of simulations, based on a candidate site of the offshore wind farm in Jeju, Korea. (author)

  14. Closed-loop control of grasping with a myoelectric hand prosthesis: which are the relevant feedback variables for force control?

    Science.gov (United States)

    Ninu, Andrei; Dosen, Strahinja; Muceli, Silvia; Rattay, Frank; Dietl, Hans; Farina, Dario

    2014-09-01

    In closed-loop control of grasping by hand prostheses, the feedback information sent to the user is usually the actual controlled variable, i.e., the grasp force. Although this choice is intuitive and logical, the force production is only the last step in the process of grasping. Therefore, this study evaluated the performance in controlling grasp strength using a hand prosthesis operated through a complete grasping sequence while varying the feedback variables (e.g., closing velocity, grasping force), which were provided to the user visually or through vibrotactile stimulation. The experiments were conducted on 13 volunteers who controlled the Otto Bock Sensor Hand Speed prosthesis. Results showed that vibrotactile patterns were able to replace the visual feedback. Interestingly, the experiments demonstrated that direct force feedback was not essential for the control of grasping force. The subjects were indeed able to control the grip strength, predictively, by estimating the grasping force from the prosthesis velocity of closing. Therefore, grasping without explicit force feedback is not completely blind, contrary to what is usually assumed. In our study we analyzed grasping with a specific prosthetic device, but the outcomes are also applicable for other devices, with one or more degrees-of-freedom. The necessary condition is that the electromyography (EMG) signal directly and proportionally controls the velocity/grasp force of the hand, which is a common approach among EMG controlled prosthetic devices. The results provide important indications on the design of closed-loop EMG controlled prosthetic systems.

  15. Interleaved Buck Converter with Variable Number of Active Phases and a Predictive Current Sharing Scheme

    DEFF Research Database (Denmark)

    Jakobsen, Lars Tønnes; Garcia, O.; Oliver, J. A.

    2008-01-01

    The efficiency of an interleaved Buck converter is typically low at light load conditions because of the switching losses in each of the switching stages. Improvements in the converter efficiency can be achieved by dynamically changing the number of active phases depending on the load current...

  16. Phase lags and coherence of X-ray variability in black hole candidates

    CERN Document Server

    Nowak, M A; Nowak, Michael A; Vaughan, Brian A

    1995-01-01

    The ``low'' (hard or ``non-thermal'') state of black hole candidates is sometimes modelled via an optically thick, hot Compton cloud that obscures a softer input source such as an accretion disk. In these models the observed output spectra consist entirely of photons reprocessed by the cloud, making it difficult to extract information about the input spectra. Recently Miller (1995) has argued that the Fourier phase (or time) lag between hard and soft X-ray photons in actuality represents the phase lags intrinsic to the input source, modulo a multiplicative factor. The phase lags thus would be a probe of the input photon source. In this paper we examine this claim and find that, although true for the limited parameter space considered by Miller, the intrinsic phase lag disappears whenever the output photon energy is much greater than the input photon energy. The remaining time lags represent a ``shelf'' due to differences between mean diffusion times across the cloud. As pointed out by Miller, the amplitude of...

  17. Optimal design variable considerations in the use of phase change materials in indirect evaporative cooling

    Science.gov (United States)

    Chilakapaty, Ankit Paul

    The demand for sustainable, energy efficient and cost effective heating and cooling solutions is exponentially increasing with the rapid advancement of computation and information technology. Use of latent heat storage materials also known as phase change materials (PCMs) for load leveling is an innovative solution to the data center cooling demands. These materials are commercially available in the form of microcapsules dispersed in water, referred to as the microencapsulated phase change slurries and have higher heat capacity than water. The composition and physical properties of phase change slurries play significant role in energy efficiency of the cooling systems designed implementing these PCM slurries. Objective of this project is to study the effect of PCM particle size, shape and volumetric concentration on overall heat transfer potential of the cooling systems designed with PCM slurries as the heat transfer fluid (HTF). In this study uniform volume heat source model is developed for the simulation of heat transfer potential using phase change materials in the form of bulk temperature difference in a fully developed flow through a circular duct. Results indicate the heat transfer potential increases with PCM volumetric concentration with gradually diminishing returns. Also, spherical PCM particles offer greater heat transfer potential when compared to cylindrical particles. Results of this project will aid in efficient design of cooling systems based on PCM slurries.

  18. Composition/Property Relationships for the Phase 2 Am-Cm Glass Variability Study

    Energy Technology Data Exchange (ETDEWEB)

    Peeler, D.

    2000-06-09

    The objective of this research was to evaluate the effect of compositional uncertainties on the primary processing and product performance criteria for potential glasses to stabilize the Tank 17.1 Am-Cm solution and to identify the AGCR in which glasses simultaneously meet both process and product performance criteria as defined for Phase 2.

  19. Nucleic Acid-Peptide Complex Phase Controlled by DNA Hybridization

    Science.gov (United States)

    Vieregg, Jeffrey; Lueckheide, Michael; Leon, Lorraine; Marciel, Amanda; Tirrell, Matthew

    When polyanions and polycations are mixed, counterion release drives formation of polymer-rich complexes that can either be solid (precipitates) or liquid (coacervates) depending on the properties of the polyelectrolytes. These complexes are important in many fields, from encapsulation of industrial polymers to membrane-free segregation of biomolecules such as nucleic acids and proteins. Condensation of long double-stranded DNA has been studied for several decades, but comparatively little attention has been paid to the polyelectrolyte behavior of oligonucleotides. We report here studies of DNA oligonucleotides (10 - 88 nt) complexed with polylysine (10 - 100 aa). Unexpectedly, we find that the phase of the resulting complexes is controlled by the hybridization state of the nucleic acid, with double-stranded DNA forming precipitates and single-stranded DNA forming coacervates. Stability increases with polyelectrolyte length and decreases with solution salt concentration, with complexes of the longer double-stranded polymers undergoing precipitate/coacervate/soluble transitions as ionic strength is increased. Mixing coacervates formed by complementary single-stranded oligonucleotides results in precipitate formation, raising the possibility of stimulus-responsive material design.

  20. Solid-phase laser-induced forward transfer of variable shapes using a liquid-crystal spatial light modulator

    Science.gov (United States)

    Pohl, R.; Jansink, M.; Römer, G. R. B. E.; Huis in `t Veld, A. J.

    2015-08-01

    Laser-induced forward transfer is a promising method for 3D printing of various materials, including metals. The ejection mechanism is complex and depends strongly on the experimental parameters, such as laser fluence and donor layer thickness. However, the process can be categorized by the physical condition of the ejected material, i.e., the donor layer is transferred in liquid phase or the material is transferred as a `pellet' in solid phase. Currently, solid-phase transfer faces several problems. Large shearing forces, occurring at the pellet perimeter during transfer, limit the similarity between the desired pellet shape and the deposited pellet shape. Furthermore, the deposited pellet may be surrounded by debris particles formed by undesired transferred donor material. This work introduces a novel approach for laser-induced forward transfer of variable shaped solid-phase pellets. A liquid-crystal spatial light modulator (SLM) is used to apply grayscale intensity modulation to an incident laser beam to shape the intensity profile. Optimized beams consist of a high fluence perimeter around an interior characterized by a lower fluence level. These beams are used successfully to transfer solid-phase pellets out of a 100-nm Au donor layer using a single laser pulse. The flexibility of the SLM allows a variable desired pellet shape. The shapes of the resulting deposited pellets show a high degree of similarity to the desired shapes. Debris-free deposited pellets are achieved by pre-machining the donor layer, prior to the transfer, using a double-pulse process.

  1. Conditions of Technical Stability on Non-Stationary Processes of Automatic Control of Variable Structure with Correlative Forming and Filtering Systems of Control Signals

    Directory of Open Access Journals (Sweden)

    Matviychuk K.S.

    2012-06-01

    Full Text Available The conditions of technical stability by measure of the dynamical states of the non-stationary control systems with variable structure are investigated in presence of filtration process of the control signals. The suitable systems of the differential equations have the changing coefficients, which are altering in time and by jumplike together with jumplike changing of the control function of the process and with simultaneous jumplike changing at the direction of the suitable phase velocity vector of the process. The criteria of technical stability by measure on finite and infinite intervals of time, asymptotical technical stability by measure, and also the criterion of the technical instability by measure of given, inwardly dependent on quality of filtering of control signals of non-stationary dynamical systems with variable structure are determiner under base of the differential inequalities method at combination with properties of the class of the absolutely positive functions, for all feasible initial disturbances from the pre-assigned by measure set of initial states of the process.

  2. FPGA-based phase control of acousto-optic modulator Fourier synthesis system through gradient descent phase-locking algorithm.

    Science.gov (United States)

    Underwood, Kenneth J; Jones, Andrew M; Gopinath, Juliet T

    2015-06-20

    We present a new application of the stochastic parallel gradient descent (SPGD) algorithm to fast active phase control in a Fourier synthesis system. Pulses (4.9 ns) with an 80 MHz repetition rate are generated by feedback from a single phase-sensitive metric. Phase control is applied via fast current modulation of a tapered amplifier using an SPGD algorithm realized on a field-programmable gate array (FPGA). The waveforms are maintained by constant active feedback from the FPGA. We also discuss the extension of this technique to many more semiconductor laser emitters in a diode laser array.

  3. Independent modal variable structure fuzzy active vibration control of thin plates laminated with photostrictive actuators

    Institute of Scientific and Technical Information of China (English)

    He Rongbo; Zheng Shijie

    2013-01-01

    Photostrictive actuators can produce photodeformation strains under illumination of ultraviolet lights.They can realize non-contact micro-actuation and vibration control for elastic plate structures.Considering the switching actuation and nonlinear dynamic characteristics of photostrictive actuators,a variable structure fuzzy active control scheme is presented to control the light intensity applied to the actuators.Firstly,independent modal vibration control equations of photoelectric laminated plates are established based on modal analysis techniques.Then,the optimal light switching function is derived to increase the range of sliding modal area,and the light intensity self-adjusting fuzzy active controller is designed.Meanwhile,a continuous function is applied to replace a sign function to reduce the variable structure control (VSC) chattering.Finally,numerical simulation is carried out,and simulation results indicate that the proposed control strategy provides better performance and control effect to plate actuation and control than velocity feedback control,and suppresses vibration effectively.

  4. The cognitive roles of behavioral variability: idiosyncratic acts as the foundation of identity and as transitional, preparatory, and confirmatory phases.

    Science.gov (United States)

    Eilam, David

    2015-02-01

    Behavior in obsessive compulsive disorder (OCD), in habitual daily tasks, and in sport and cultural rituals is deconstructed into elemental acts and categorized into common acts, performed by all individuals completing a similar task, and idiosyncratic acts, not performed by all individuals. Never skipped, common acts establish the pragmatic part of motor tasks. Repetitive performance of a few common acts renders rituals a rigid form, whereby common acts may serve as memes for cultural transmission. While idiosyncratic acts are not pragmatically necessary for task completion, they fulfill important cognitive roles. They form a long preparatory phase in tasks that involve high stakes, and a long confirmatory phase in OCD rituals. Idiosyncratic acts also form transitional phases between motor tasks, and are involved in establishing identity and preserving the flexibility necessary for adapting to varying circumstances. Behavioral variability, as manifested in idiosyncrasy, thus does not seem to be a noise or by-product of motor activity, but an essential cognitive component that has been preserved in the evolution of behavioral patterns, similar to the genetic variability in biology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Performance comparison of control schemes for variable-speed wind turbines

    Science.gov (United States)

    Bottasso, C. L.; Croce, A.; Savini, B.

    2007-07-01

    We analyze the performance of different control schemes when applied to the regulation problem of a variable-speed representative wind turbine. In particular, we formulate and compare a wind-scheduled PID, a LQR controller and a novel adaptive non-linear model predictive controller, equipped with observers of the tower states and wind. The simulations include gusts and turbulent winds of varying intensity in nominal as well as off-design operating conditions. The experiments highlight the possible advantages of model-based non-linear control strategies.

  6. Performance comparison of control schemes for variable-speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bottasso, C L; Croce, A; Savini, B [Dipartimento di Ingegneria Aerospaziale, Politecnico di Milano, Via La Masa 34 I-20156 Milan (Italy)

    2007-07-15

    We analyze the performance of different control schemes when applied to the regulation problem of a variable-speed representative wind turbine. In particular, we formulate and compare a wind-scheduled PID, a LQR controller and a novel adaptive non-linear model predictive controller, equipped with observers of the tower states and wind. The simulations include gusts and turbulent winds of varying intensity in nominal as well as off-design operating conditions. The experiments highlight the possible advantages of model-based non-linear control strategies.

  7. Trajectory tracking in 2D under fuzzy controller with variable sampling

    Directory of Open Access Journals (Sweden)

    Ján Cigánek

    2015-12-01

    Full Text Available The paper deals with an effective approach of the robust controller design based on the fuzzy logic, and algorithms for variable sampling of trajectory points to improve the control performance of trajectory tracking. The proposed controller design and sampling algorithms are verified in the case study of the selected mechatronic system. All presented results are reached in co-simulation of two different modeling environments, Matlab-Simulink and MSC Adams. MSC Adams is used for the dynamics of the mechatronic system and Matlab-Simulink for the control part of the co-simulation, respectively.

  8. A hybrid disturbance rejection control solution for variable valve timing system of gasoline engines.

    Science.gov (United States)

    Xie, Hui; Song, Kang; He, Yu

    2014-07-01

    A novel solution for electro-hydraulic variable valve timing (VVT) system of gasoline engines is proposed, based on the concept of active disturbance rejection control (ADRC). Disturbances, such as oil pressure and engine speed variations, are all estimated and mitigated in real-time. A feed-forward controller was added to enhance the performance of the system based on a simple and static first principle model, forming a hybrid disturbance rejection control (HDRC) strategy. HDRC was validated by experimentation and compared with an existing manually tuned proportional-integral (PI) controller. The results show that HDRC provided a faster response and better tolerance of engine speed and oil pressure variations.

  9. A Fuzzy Logic Controller to Increase Fault Ride-Through Capability of Variable Speed Wind Turbines

    Directory of Open Access Journals (Sweden)

    Geev Mokryani

    2012-01-01

    Full Text Available A fuzzy controller for improving Fault Ride-Through (FRT capability of Variable Speed Wind Turbines (WTs equipped with Doubly Fed Induction Generator (DFIG is presented. The controller is designed in order to compensate the voltage at the Point of Common Coupling (PCC by regulating the reactive and active power generated by WTs. The performances of the controller are evaluated in some case studies considering a different number of wind farms in different locations. Simulations, carried out on a real 37-bus Italian weak distribution system, confirmed that the proposed controller can enhance the FRT capability in many cases.

  10. A disturbance decoupling nonlinear control law for variable speed wind turbines

    DEFF Research Database (Denmark)

    Thomsen, Sven Creutz; Poulsen, Niels Kjølstad

    2007-01-01

    This paper describes a nonlinear control law for controlling variable speed wind turbines using feedback linearization. The novel aspect of the control law is its ability to decouple the effect of wind fluctuations. Furthermore, the transformation to feedback linearizable coordinates is chosen...... intelligently so that the majority of the system structure is invariant under the transformation. Consequently the physical interpretation is preserved. The method assumes that the effective wind speed and acceleration are estimated from measurements on the wind turbine. The performance of the control...

  11. Water outlet control mechanism for fuel cell system operation in variable gravity environments

    Science.gov (United States)

    Vasquez, Arturo (Inventor); McCurdy, Kerri L. (Inventor); Bradley, Karla F. (Inventor)

    2007-01-01

    A self-regulated water separator provides centrifugal separation of fuel cell product water from oxidant gas. The system uses the flow energy of the fuel cell's two-phase water and oxidant flow stream and a regulated ejector or other reactant circulation pump providing the two-phase fluid flow. The system further uses a means of controlling the water outlet flow rate away from the water separator that uses both the ejector's or reactant pump's supply pressure and a compressibility sensor to provide overall control of separated water flow either back to the separator or away from the separator.

  12. LQR Control of Wind Excited Benchmark Building Using Variable Stiffness Tuned Mass Damper

    Directory of Open Access Journals (Sweden)

    S. N. Deshmukh

    2014-01-01

    Full Text Available LQR control of wind induced motion of a benchmark building is considered. The building is fitted with a semiactive variable stiffness tuned mass damper adapted from the literature. The nominal stiffness of the device corresponds to the fundamental frequency of the building and is included in the system matrix. This results in a linear time-invariant system, for which the desired control force is computed using LQR control. The control force thus computed is then realized by varying the device stiffness around its nominal value by using a simple control law. A nonlinear static analysis is performed in order to establish the range of linearity, in terms of the device (configuration angle, for which the control law is valid. Results are obtained for the cases of zero and nonzero structural stiffness variation. The performance criteria evaluated show that the present method provides displacement control that is comparable with that of two existing controllers. The acceleration control, while not as good as that obtained with the existing active controller, is comparable or better than that obtained with the existing semiactive controller. By using substantially less power as well as control force, the present control yields comparable displacement control and reasonable acceleration control.

  13. Study and experimental verification of control tuning strategies in a variable speed wind energy conversion system

    Energy Technology Data Exchange (ETDEWEB)

    Zaragoza, Jordi; Pou, Josep; Arias, Antoni [Electronic Engineering Dept., Technical University of Catalonia, Campus Terrassa, C. Colom 1, 08222 Terrassa (Spain); Spiteri, Cyril [Department of Industrial Electrical Power Conversion, University of Malta, Faculty of Engineering, Msida (Malta); Robles, Eider; Ceballos, Salvador [Energy Unit, Robotiker-Tecnalia Technology Corporation, Zamudio, Basque Country (Spain)

    2011-05-15

    This paper analyzes and compares different control tuning strategies for a variable speed wind energy conversion system (WECS) based on a permanent-magnet synchronous generator (PMSG). The aerodynamics of the wind turbine (WT) and a PMSG have been modeled. The control strategy used in this research is composed of three regulators, which may be based on either linear or nonlinear controllers. In this analysis, proportional-integral (PI) linear controllers have been used. Two different tuning strategies are analyzed and compared. The main goal is to enhance the overall performance by achieving a low sensitivity to disturbances and minimal overshoot under variable operating conditions. Finally, the results have been verified by an experimental WECS laboratory prototype. (author)

  14. A new active variable stiffness suspension system using a nonlinear energy sink-based controller

    Science.gov (United States)

    Anubi, Olugbenga Moses; Crane, Carl D.

    2013-10-01

    This paper presents the active case of a variable stiffness suspension system. The central concept is based on a recently designed variable stiffness mechanism which consists of a horizontal control strut and a vertical strut. The horizontal strut is used to vary the load transfer ratio by actively controlling the location of the point of attachment of the vertical strut to the car body. The control algorithm, effected by a hydraulic actuator, uses the concept of nonlinear energy sink (NES) to effectively transfer the vibrational energy in the sprung mass to a control mass, thereby reducing the transfer of energy from road disturbance to the car body at a relatively lower cost compared to the traditional active suspension using the skyhook concept. The analyses and simulation results show that a better performance can be achieved by subjecting the point of attachment of a suspension system, to the chassis, to the influence of a horizontal NES system.

  15. A Robust Adaptive Sliding Mode Control for PMLSM with Variable Velocity Profile Over Wide Range

    Directory of Open Access Journals (Sweden)

    Payam Ghaebi Panah

    2015-07-01

    Full Text Available An adaptive robust variable structure speed controller is designed for wide range of desired velocity control of a Permanent Magnet Linear Synchronous Motor (PMLSM. This is performed for comprehensive nonlinear model of PMLSM including non-idealities such as detent force, parameter uncertainty, unpredicted disturbance and nonlinear friction. The proposed method is based on the robust Sliding Mode Control (SMC in combination with an adaptive strategy for a wide range of velocity. The simulation results are provided for the above mentioned comprehensive model of PMLSM with a variable velocity profile. Moreover, as an evaluation criterion, a Proportional-Integral (PI controller is designed whose parameters are optimally tuned by the Particle Swarm Optimization (PSO algorithm for better comparison.

  16. Design of a variable width pulse generator feasible for manual or automatic control

    Science.gov (United States)

    Vegas, I.; Antoranz, P.; Miranda, J. M.; Franco, F. J.

    2017-01-01

    A variable width pulse generator featuring more than 4-V peak amplitude and less than 10-ns FWHM is described. In this design the width of the pulses is controlled by means of the control signal slope. Thus, a variable transition time control circuit (TTCC) is also developed, based on the charge and discharge of a capacitor by means of two tunable current sources. Additionally, it is possible to activate/deactivate the pulses when required, therefore allowing the creation of any desired pulse pattern. Furthermore, the implementation presented here can be electronically controlled. In conclusion, due to its versatility, compactness and low cost it can be used in a wide variety of applications.

  17. Design and Experiment of Slave Computer Control System for Applying Variable-rate Liquid Fertilizer

    Institute of Scientific and Technical Information of China (English)

    Zhang Ying-zi; Chen Hai-tao; Hou Shou-yin; Ji Wen-yi; Ouyang Bin-lin; Dun Guo-qiang; Zhang Ji-cheng

    2015-01-01

    In order to increase the applying rate of liquid fertilizer and reduce environmental pollution, a slave computer control system for applying variable-rate liquid fertilizer was designed. The system used SMC as core processor and electrically controlled pressure regulator as execution component. The characteristic equation of the system was obtained by using classical control theory. Results indicated that the characteristic equation met the requirements of routh-criterion, which indicated the working process of the system was stable. Performance of the slave computer was verified via bench tests. Results demonstrated that there was no significant influence on the response from interclass error. The fertilization error was less than 0.9, and the fertilization accuracy was larger than 97%. The liquid fertilizer emitted by the fertilizing devices had no significant difference in uniformity, which met the demands of the slave computer control system for applying variable-rate liquid fertilizer.

  18. On which timescales do gas transfer velocities control North Atlantic CO2 flux variability?

    Science.gov (United States)

    Couldrey, Matthew P.; Oliver, Kevin I. C.; Yool, Andrew; Halloran, Paul R.; Achterberg, Eric P.

    2016-05-01

    The North Atlantic is an important basin for the global ocean's uptake of anthropogenic and natural carbon dioxide (CO2), but the mechanisms controlling this carbon flux are not fully understood. The air-sea flux of CO2, F, is the product of a gas transfer velocity, k, the air-sea CO2 concentration gradient, ΔpCO2, and the temperature- and salinity-dependent solubility coefficient, α. k is difficult to constrain, representing the dominant uncertainty in F on short (instantaneous to interannual) timescales. Previous work shows that in the North Atlantic, ΔpCO2 and k both contribute significantly to interannual F variability but that k is unimportant for multidecadal variability. On some timescale between interannual and multidecadal, gas transfer velocity variability and its associated uncertainty become negligible. Here we quantify this critical timescale for the first time. Using an ocean model, we determine the importance of k, ΔpCO2, and α on a range of timescales. On interannual and shorter timescales, both ΔpCO2 and k are important controls on F. In contrast, pentadal to multidecadal North Atlantic flux variability is driven almost entirely by ΔpCO2; k contributes less than 25%. Finally, we explore how accurately one can estimate North Atlantic F without a knowledge of nonseasonal k variability, finding it possible for interannual and longer timescales. These findings suggest that continued efforts to better constrain gas transfer velocities are necessary to quantify interannual variability in the North Atlantic carbon sink. However, uncertainty in k variability is unlikely to limit the accuracy of estimates of longer-term flux variability.

  19. Variable Gravity Effects on the Cooling Performance of a Single Phase Confined Spray

    Science.gov (United States)

    Michalak, Travis; Yerkes, Kirk; Baysinger, Karri; McQuillen, John

    2005-01-01

    The objective of this paper is to discuss the testing of a spray cooling experiment designed to be flown on NASA's KC-135 Reduced Gravity Testing Platform. Spray cooling is an example of a thermal management technique that may be utilized in high flux heat acquisition and high thermal energy transport concepts. Many researchers have investigated the utility of spray cooling for the thermal management of devices generating high heat fluxes. However, there has been little research addressing the physics and ultimate performance of spray cooling in a variable gravity environment. An experimental package, consisting of a spray chamber coupled to a fluid delivery loop system, was fabricated for variable gravity flight tests. The spray chamber contains two opposing nozzles spraying on target Indium Tin Oxide (ITO) heaters. These heaters are mounted on glass pedestals, which are part of a sump system to remove unconstrained liquid from the test chamber. Liquid is collected in the sumps and returned to the fluid delivery loop. Thermocouples mounted in and around the pedestals are used to determine both the heat loss through the underside of the IT0 heater and the heat extracted by the spray. A series of flight tests were carried out aboard the KC-135, utilizing the ability of the aircraft to produce various gravity conditions. During the flight tests, for a fixed flow rate, heat input was varied at 20, 30, 50, and 80W with variable gravities of 0.01, 0.16, 0.36, and 1.8g. Flight test data was compared to terrestrial baseline data in addition to analytical and numerical solutions to evaluate the heat transfer in the heater and support structure . There were significant differences observed in the spray cooling performance as a result of variable gravity conditions and heat inputs. In general, the Nussult number at the heater surface was found to increase with decreasing gravity conditions for heat loads greater than 30W.

  20. Power transmission line operating modes calculation with controllable phase shifters

    Science.gov (United States)

    Astashev, M. G.; Novikov, M. A.; Panfilov, D. I.; Rashitov, P. A.; Remizevich, T. V.; Fedorova, M. I.

    2016-12-01

    The article contains the analysis of the influence of the phase shifter (PS) on the energy processes in the power transmission line in terms of the two-unit model of the electric network. The approach to synthesis of the models regulated by the phase shifter providing for both calculation of the steady operation modes of the electric networks with the phase shifters and research of the electromagnetic processes and designing of the device itself is offered.

  1. Heart Rate Variability as a Measure of Airport Ramp-Traffic Controllers Workload

    Science.gov (United States)

    Hayashi, Miwa; Dulchinos, Victoria Lee

    2016-01-01

    Heart Rate Variability (HRV) has been reported to reflect the person's cognitive and emotional stress levels, and may offer an objective measure of human-operator's workload levels, which are recorded continuously and unobtrusively to the task performance. The present paper compares the HRV data collected during a human-in-the-loop simulation of airport ramp-traffic control operations with the controller participants' own verbal self-reporting ratings of their workload.

  2. Robust Active Disturbance Rejection Control Approach to Maximize Energy Capture in Variable-Speed Wind Turbines

    OpenAIRE

    Horacio Coral-Enriquez; John Cortés-Romero; Germán A. Ramos

    2013-01-01

    This paper proposes an alternative robust observer-based linear control technique to maximize energy capture in a 4.8 MW horizontal-axis variable-speed wind turbine. The proposed strategy uses a generalized proportional integral (GPI) observer to reconstruct the aerodynamic torque in order to obtain a generator speed optimal trajectory. Then, a robust GPI observer-based controller supported by an active disturbance rejection (ADR) approach allows asymptotic tracking of the generator speed opt...

  3. Control of Flexible Joint Manipulator via Variable Structure Rule-Based Fuzzy Control and Chaos Anti-Control with Experimental Validation

    Directory of Open Access Journals (Sweden)

    Mojtaba Rostami Kandroodi

    2014-03-01

    Full Text Available This paper presents a variable structure rule-based fuzzy control for trajectory tracking and vibration control of a flexible joint manipulator by using chaotic anti-control. Based on Lyapunov stability theory for variable structure control and fuzzy rules, the nonlinear controller and some generic sufficient conditions for global asymptotic control are attained. The fuzzy rules are directly constructed subject to a Lyapunov function obtained from variable structure surfaces such that the error dynamics of control problem satisfy stability in the Lyapunov sense. Also in this study, the anti-control is applied to reduce the deflection angle of flexible joint system. To achieve this goal, the chaos dynamic must be created in the flexible joint system. So, the flexible joint system has been synchronized to chaotic gyroscope system. In this study, control and anti-control concepts are applied to achieve the high quality performance of flexible joint system. It is tried to design a controller which is capable to satisfy the control and anti- control aims. The performances of the proposed control are examined in terms of input tracking capability, level of vibration reduction and time response specifications. Finally, the efficacy of the proposed method is validated through experimentation on QUANSER’s flexible-joint manipulator.

  4. Power Control of Permanent Magnet Generator Based Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2009-01-01

    When the wind power accounts for a large portion of the grid, it will be required to regulate the active power and reactive power. This paper investigates a MWlevel variable speed wind turbine with a permanent magnet synchronous generator (PMSG). The power control capabilities of two kinds...

  5. Is Low Empathy Related to Bullying after Controlling for Individual and Social Background Variables?

    Science.gov (United States)

    Jolliffe, Darrick; Farrington, David P.

    2011-01-01

    This paper examines the relationship between low empathy and bullying while also controlling for the impact of a number of other individual and social background variables linked with bullying. This included the relationship to the prevalence of bullying, but also to the frequency and type of bullying. Questionnaires were completed by 720…

  6. FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM

    Science.gov (United States)

    The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

  7. FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM

    Science.gov (United States)

    The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

  8. Morphological and physiological variability of species of meloidogyne in West Africa and implications of their control

    NARCIS (Netherlands)

    Netscher, C.

    1978-01-01

    The extreme morphological and physiological variability of certain rootknot nematodes (Meloidogyne spp.) and its implication on the development of control methods of these parasites, based upon crop rotations and the use of resistant varieties of otherwise susceptible crops are discussed.In a review

  9. Wind tunnel experiments to prove a hydraulic passive torque control concept for variable speed wind turbines

    NARCIS (Netherlands)

    Diepeveen, N.F.B.; Jarquin-Laguna, A.

    2014-01-01

    In this paper the results are presented of experiments to prove an innovative concept for passive torque control of variable speed wind turbines using fluid power technology. It is demonstrated that by correctly configuring the hydraulic drive train, the wind turbine rotor operates at or near maximu

  10. Using Statistical Process Control Charts to Study Stuttering Frequency Variability during a Single Day

    Science.gov (United States)

    Karimi, Hamid; O'Brian, Sue; Onslow, Mark; Jones, Mark; Menzies, Ross; Packman, Ann

    2013-01-01

    Purpose: Stuttering varies between and within speaking situations. In this study, the authors used statistical process control charts with 10 case studies to investigate variability of stuttering frequency. Method: Participants were 10 adults who stutter. The authors counted the percentage of syllables stuttered (%SS) for segments of their speech…

  11. Using Statistical Process Control Charts to Study Stuttering Frequency Variability during a Single Day

    Science.gov (United States)

    Karimi, Hamid; O'Brian, Sue; Onslow, Mark; Jones, Mark; Menzies, Ross; Packman, Ann

    2013-01-01

    Purpose: Stuttering varies between and within speaking situations. In this study, the authors used statistical process control charts with 10 case studies to investigate variability of stuttering frequency. Method: Participants were 10 adults who stutter. The authors counted the percentage of syllables stuttered (%SS) for segments of their speech…

  12. Further Analysis of Variables That Affect Self-Control with Aversive Events

    Science.gov (United States)

    Perrin, Christopher J.; Neef, Nancy A.

    2012-01-01

    The purpose of this study was to examine variables that affect self-control in the context of academic task completion by elementary school children with autism. In the baseline assessment of Study 1, mathematics problem completion was shown to be an aversive event, and sensitivity to task magnitude, task difficulty, and delay to task completion…

  13. Wind tunnel experiments to prove a hydraulic passive torque control concept for variable speed wind turbines

    NARCIS (Netherlands)

    Diepeveen, N.F.B.; Jarquin-Laguna, A.

    2014-01-01

    In this paper the results are presented of experiments to prove an innovative concept for passive torque control of variable speed wind turbines using fluid power technology. It is demonstrated that by correctly configuring the hydraulic drive train, the wind turbine rotor operates at or near maximu

  14. Physical activity, mindfulness meditation, or heart rate variability biofeedback for stress reduction: a randomized controlled trial

    NARCIS (Netherlands)

    van der Zwan, J.E.; de Vente, W.; Huizink, A.C.; Bögels, S.M.; de Bruin, E.I.

    2015-01-01

    In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing

  15. Emotional variability during mother-adolescent conflict interactions: Longitudinal links to adolescent disclosure and maternal control

    NARCIS (Netherlands)

    Van der Giessen, D.; Branje, S.; Keijsers, L.; Van Lier, P.A.C.; Koot, H.M.; Meeus, W.

    2014-01-01

    The aim of this study was to examine relations of emotional variability during mother-adolescent conflict interactions in early adolescence with adolescent disclosure and maternal control in early and late adolescence. Data were used from 92 mother-adolescent dyads (M age T1 = 13.05; 65.20% boys) th

  16. Single motor–variable stiffness actuator using bistable switching mechanisms for independent motion and stiffness control

    NARCIS (Netherlands)

    Groothuis, S.S.; Carloni, R.; Stramigioli, S.

    2016-01-01

    This paper presents a proof of concept of a variable stiffness actuator (VSA) that uses only one (high power) input motor. In general, VSAs use two (high power) motors to be able to control both the output position and the output stiffness, which possibly results in a heavy, and bulky system. In thi

  17. Physical activity, mindfulness meditation, or heart rate variability biofeedback for stress reduction: a randomized controlled trial

    NARCIS (Netherlands)

    Zwan, van der J.E.; Vente, de W.; Huizink, A.C.; Bögels, S.M.; Bruin, de E.I.

    2015-01-01

    In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing

  18. Integrated Variable Speed Limits Control and Ramp Metering for Bottleneck Regions on Freeway

    Directory of Open Access Journals (Sweden)

    Ming-hui Ma

    2015-01-01

    Full Text Available To enhance the efficiency of the existing freeway system and therefore to mitigate traffic congestion and related problems on the freeway mainline lane-drop bottleneck region, the advanced strategy for bottleneck control is essential. This paper proposes a method that integrates variable speed limits and ramp metering for freeway bottleneck region control to relieve the chaos in bottleneck region. To this end, based on the analyses of spatial-temporal patterns of traffic flow, a macroscopic traffic flow model is extended to describe the traffic flow operating characteristic by considering the impacts of variable speed limits in mainstream bottleneck region. In addition, to achieve the goal of balancing the priority of the vehicles on mainline and on-ramp, increasing capacity, and reducing travel delay on bottleneck region, an improved control model, as well as an advanced control strategy that integrates variable speed limits and ramp metering, is developed. The proposed method is tested in simulation for a real freeway infrastructure feed and calibrates real traffic variables. The results demonstrate that the proposed method can substantially improve the traffic flow efficiency of mainline and on-ramp and enhance the quality of traffic flow at the investigated freeway mainline bottleneck.

  19. Soil Physical and Environmental Conditions Controlling Patterned-Ground Variability at a Continuous Permafrost Site, Svalbard

    DEFF Research Database (Denmark)

    Watanabe, Tatsuya; Matsuoka, Norikazu; Christiansen, Hanne Hvidtfeldt

    2017-01-01

    This study examines soil physical and environmental conditions controlling patterned-ground variability on an alluvial fan in a continuous permafrost landscape, at Adventdalen, Svalbard. On-site monitoring of ground temperature, soil moisture and snow depth, laboratory analyses of soil physical...

  20. Controlling gradient phase distributions in a model of active antenna array with locally coupled elements

    Science.gov (United States)

    Mishagin, K. G.; Shalfeev, V. D.

    2006-12-01

    The regime of synchronization with a certain gradient phase distribution and the possibility of controlling such distribution in a linear array of oscillators coupled by phase-locked loops (PLLs) have been theoretically studied. It is shown that a constant phase progression can be controlled by manipulating collective dynamics, with oscillator eigenfrequencies and coupling coefficients being the control parameters. The proposed principle of control, based on the nonlinear dynamics of PLL-coupled oscillators, can be used in solving the problems of phasing and controlled beam scanning in antenna arrays operating in different frequency bands.