NASA Astrophysics Data System (ADS)
Nondahl, T. A.; Richter, E.
1980-09-01
A design study of two types of single sided (with a passive rail) linear electric machine designs, namely homopolar linear synchronous machines (LSM's) and linear induction machines (LIM's), is described. It is assumed the machines provide tractive effort for several types of light rail vehicles and locomotives. These vehicles are wheel supported and require tractive powers ranging from 200 kW to 3735 kW and top speeds ranging from 112 km/hr to 400 km/hr. All designs are made according to specified magnetic and thermal criteria. The LSM advantages are a higher power factor, much greater restoring forces for track misalignments, and less track heating. The LIM advantages are no need to synchronize the excitation frequency precisely to vehicle speed, simpler machine construction, and a more easily anchored track structure. The relative weights of the two machine types vary with excitation frequency and speed; low frequencies and low speeds favor the LSM.
Linear Synchronous Motor Repeatability Tests
Ward, C.R.
2002-10-18
A cart system using linear synchronous motors was being considered for the Plutonium Immobilization Plant (PIP). One of the applications in the PIP was the movement of a stack of furnace trays, filled with the waste form (pucks) from a stacking/unstacking station to several bottom loaded furnaces. A system was ordered to perform this function in the PIP Ceramic Prototype Test Facility (CPTF). This system was installed and started up in SRTC prior to being installed in the CPTF. The PIP was suspended and then canceled after the linear synchronous motor system was started up. This system was used to determine repeatability of a linear synchronous motor cart system for the Modern Pit Facility.
Linear synchronous motor having enhanced levitational forces
Tozoni, O.
1993-07-06
A linear synchronous motor for a high speed vehicle is described comprising: (a) a linear stator assembly divided into sections and having an air gap, the stator assembly generating a magnetic field traveling wave in the air gap from an alternating current source, the traveling wave having variable speeds and accelerations along different sections of the stator assembly; (b) a rotor assembly having at least one propulsion magnet forming at least one pole-pitch of a selected length that is selectively variable while the vehicle is in motion, the magnet including an upper portion, a lower portion spaced apart from the upper portion, and a nonmagnetic coupler rigidly coupling the upper portion to the lower portion, the rotor assembly coupled to the vehicle and disposed in the air gap of the stator and movable laterally with respect to the stator, the rotor assembly generating a magnetic flux that produces an attractive force between a magnetic field of the rotor assembly and the traveling wave of the stator assembly, the magnetic field of the rotor assembly propelling the vehicle and generating a levitation force levitating the vehicle; and (c) a synchronizing unit operatively associated with the rotor assembly to vary the length of the pole-pitch such that the pole-pitch length is substantially equal to one-half the length of the traveling wave at any given position along the linear stator assembly.
Fault Tolerant Homopolar Magnetic Bearings
NASA Technical Reports Server (NTRS)
Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert
2003-01-01
Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.
Magnetic levitation configuration incorporating levitation, guidance and linear synchronous motor
Coffey, Howard T.
1993-01-01
A propulsion and suspension system for an inductive repulsion type magnetically levitated vehicle which is propelled and suspended by a system which includes propulsion windings which form a linear synchronous motor and conductive guideways, adjacent to the propulsion windings, where both combine to partially encircling the vehicle-borne superconducting magnets. A three phase power source is used with the linear synchronous motor to produce a traveling magnetic wave which in conjunction with the magnets propel the vehicle. The conductive guideway combines with the superconducting magnets to provide for vehicle leviation.
Synchronization of fractional-order linear complex networks.
Wang, Junwei; Zeng, Caibin
2015-03-01
In this paper, we concentrate on the synchronization problem of fractional-order complex networks with general linear dynamics under connected topology. By introducing a pseudo-state transformation, the problem is converted into an equivalent simultaneous stabilization problem of independent subsystems, which is characterized by nonzero eigenvalues of the Laplacian matrix. Then, sufficient conditions in terms of linear matrix inequalities (LMIs) for synchronization are established, which can be easily solved by efficient convex optimization algorithms. Finally, three examples are provided to illustrate the effectiveness of the proposed method. PMID:25467542
Magnetic levitation configuration incorporating levitation, guidance and linear synchronous motor
Coffey, H.T.
1992-12-31
A propulsion and suspension system for an inductive repulsion type magnetically levitated vehicle which is propelled and suspended by a system which includes propulsion windings which form a linear synchronous motor and conductive guideways, adjacent to the propulsion windings, where both combine to partially encircling the vehicle-borne superconducting magnets. A three phase power source is used with the linear synchronous motor to produce a traveling magnetic wave which in conjunction with the magnets propel the vehicle. The conductive guideway combines with the superconducting magnets to provide for vehicle leviation.
Magnetic levitation configuration incorporating levitation, guidance and linear synchronous motor
Coffey, H.T.
1993-10-19
A propulsion and suspension system for an inductive repulsion type magnetically levitated vehicle which is propelled and suspended by a system which includes propulsion windings which form a linear synchronous motor and conductive guideways, adjacent to the propulsion windings, where both combine to partially encircling the vehicle-borne superconducting magnets. A three phase power source is used with the linear synchronous motor to produce a traveling magnetic wave which in conjunction with the magnets propel the vehicle. The conductive guideway combines with the superconducting magnets to provide for vehicle levitation. 3 figures.
Homopolar motor with dual rotors
Hsu, John S.
1998-01-01
A homopolar motor (10) has a field rotor (15) mounted on a frame (11) for rotation in a first rotational direction and for producing an electromagnetic field, and an armature rotor (17) mounted for rotation on said frame (11) within said electromagnetic field and in a second rotational direction counter to said first rotational direction of said field rotor (15). The two rotors (15, 17) are coupled through a 1:1 gearing mechanism (19), so as to travel at the same speed but in opposite directions. This doubles the output voltage and output power, as compared to a motor in which only the armature is rotated. Several embodiments are disclosed.
Homopolar motor with dual rotors
Hsu, J.S.
1998-12-01
A homopolar motor has a field rotor mounted on a frame for rotation in a first rotational direction and for producing an electromagnetic field, and an armature rotor mounted for rotation on said frame within said electromagnetic field and in a second rotational direction counter to said first rotational direction of said field rotor. The two rotors are coupled through a 1:1 gearing mechanism, so as to travel at the same speed but in opposite directions. This doubles the output voltage and output power, as compared to a motor in which only the armature is rotated. Several embodiments are disclosed. 7 figs.
Position sensor for linear synchronous motors employing halbach arrays
Post, Richard Freeman
2014-12-23
A position sensor suitable for use in linear synchronous motor (LSM) drive systems employing Halbach arrays to create their magnetic fields is described. The system has several advantages over previously employed ones, especially in its simplicity and its freedom from being affected by weather conditions, accumulated dirt, or electrical interference from the LSM system itself.
Propulsion control of superconducting linear synchronous motor vehicle
Sakamoto, Tetsuzo; Shiromizu, Tsunehiro
1997-09-01
The armature current of a superconducting Linear Synchronous Motor (LSM) for a maglev vehicle is controlled to produce a suitable propulsion force so that the vehicle follows the reference speed signal sent from a control station. Besides the power is supplied from some inverters to the LSM armature sections where the vehicle exists. This paper shows an exact mathematical modeling of the propulsion control system to treat the system analytically, which is used for designing controllers and performance computer simulations. The calculated results include the simulations when the vehicle goes through power feeder section borders and tunnels that have a large aerodynamic drag force with taking account of an inverter failure.
Improved energy density homopolar generator
NASA Astrophysics Data System (ADS)
Walls, W. A.; Weldon, Wm. F.; Driga, M. D.; Manifold, S. M.; Woodson, H. H.
1986-11-01
The preliminary design of a self excited, air-core (SEAC) homopolar generator (HPG) which stores about 250 MJ inertially and is capable of delivering 3.2 MA current pulses is presented. In aiming for maximum energy density in an HPG and inductor power supply for electromagnetic (EM) accelerators, the improved energy density (IED) machine uses its self-excited field coils as energy storage inductors and a lightweight graphite reinforced flywheel for inertial energy storage. Weighing approximately 5,000 kg, the design represents a twenty-fold increase in mass energy density over the state of the art and addresses the problem of trapping flux in the rotor during discharge by separating the voltage generating and energy storage functions. Voltage is generated across a squirrel-cage rotor armature by an opposed pair of five-turn cryogenically cooled field coils/inductors. Inertial energy is stored in a graphite-reinforced epoxy flywheel which will operate at a maximum tip speed of 1,100 m/s. The machine is expected to develop about 500 V at half speed while charging the coils to 130 MJ at 3.2 MA. Peak output voltage during discharge of coils will be roughly 10 kV.
Westinghouse programs in pulsed homopolar power supplies
NASA Technical Reports Server (NTRS)
Litz, D. C.; Mullan, E.
1984-01-01
This document details Westinghouse's ongoing study of homopolar machines since 1929 with the major effort occurring in the early 1970's to the present. The effort has enabled Westinghouse to develop expertise in the technology required for the design, fabrication and testing of such machines. This includes electrical design, electromagnetic analysis, current collection, mechanical design, advanced cooling, stress analysis, transient rotor performance, bearing analysis and seal technology. Westinghouse is using this capability to explore the use of homopolar machines as pulsed power supplies for future systems in both military and commercial applications.
Non-linear power spectra in the synchronous gauge
NASA Astrophysics Data System (ADS)
Hwang, Jai-chan; Noh, Hyerim; Jeong, Donghui; Gong, Jinn-Ouk; Biern, Sang Gyu
2015-05-01
We study the non-linear corrections to the matter and velocity power spectra in the synchronous gauge (SG). For the leading correction to the non-linear power spectra, we consider the perturbations up to third order in a zero-pressure fluid in a flat cosmological background. Although the equations in the SG happen to coincide with those in the comoving gauge (CG) to linear order, they differ from second order. In particular, the second order hydrodynamic equations in the SG are apparently in the Lagrangian form, whereas those in the CG are in the Eulerian form. The non-linear power spectra naively presented in the original SG show rather pathological behavior quite different from the result of the Newtonian theory even on sub-horizon scales. We show that the pathology in the nonlinear power spectra is due to the absence of the convective terms in, thus the Lagrangian nature of, the SG. We show that there are many different ways of introducing the corrective convective terms in the SG equations. However, the convective terms (Eulerian modification) can be introduced only through gauge transformations to other gauges which should be the same as the CG to the second order. In our previous works we have shown that the density and velocity perturbation equations in the CG exactly coincide with the Newtonian equations to the second order, and the pure general relativistic correction terms starting to appear from the third order are substantially suppressed compared with the relativistic/Newtonian terms in the power spectra. As a result, we conclude that the SG per se is an inappropriate coordinate choice in handling the non-linear matter and velocity power spectra of the large-scale structure where observations meet with theories.
Motional Mechanisms of Homopolar Motors & Rollers
ERIC Educational Resources Information Center
Wong, H. K.
2009-01-01
The strong Nd[subscript 2]Fe[subscript 14]B permanent magnet has facilitated development of various fascinating yet simple homopolar motors. However, the physics of these devices is often not explained, or is explained incorrectly. A major concern is that Newton's third law was overlooked in some of the earlier articles. In this paper, I will…
Chaotic synchronization in Bose-Einstein condensate of moving optical lattices via linear coupling
NASA Astrophysics Data System (ADS)
Zhang, Zhi-Ying; Feng, Xiu-Qin; Yao, Zhi-Hai; Jia, Hong-Yang
2015-11-01
A systematic study of the chaotic synchronization of Bose-Einstein condensed body is performed using linear coupling method based on Lyapunov stability theory, Sylvester’s criterion, and Gerschgorin disc theorem. The chaotic synchronization of Bose-Einstein condensed body in moving optical lattices is realized by linear coupling. The relationship between the synchronization time and coupling coefficient is obtained. Both the single-variable coupling and double-variable coupling are effective. The results of numerical calculation prove that the chaotic synchronization of double-variable coupling is faster than that of single-variable coupling and small coupling coefficient can achieve the chaotic synchronization. Weak noise has little influence on synchronization effect, so the linear coupling technology is suitable for the chaotic synchronization of Bose-Einstein condensate. Project supported by the Industrial Technology Research and Development Special Project of Jilin Province, China (Grant No. 2013C46) and the Natural Science Foundation of Jilin Province, China (Grant No. 20101510).
The circular form of the linear superconducting machine for marine propulsion
NASA Astrophysics Data System (ADS)
Rakels, J. H.; Mahtani, J. L.; Rhodes, R. G.
1981-01-01
The superconducting linear synchronous machine (LSM) is an efficient method of propulsion of advanced ground transport systems and can also be used in marine engineering for the propulsion of large commercial vessels, tankers, and military ships. It provides high torque at low shaft speeds and ease of reversibility; a circular LSM design is proposed as a drive motor. The equipment is compared with the superconducting homopolar motors, showing flexibility in design, built in redundancy features, and reliability.
NASA Astrophysics Data System (ADS)
Pikovsky, Arkady; Rosenblum, Michael; Kurths, Jürgen
2003-04-01
Preface; 1. Introduction; Part I. Synchronization Without Formulae: 2. Basic notions: the self-sustained oscillator and its phase; 3. Synchronization of a periodic oscillator by external force; 4. Synchronization of two and many oscillators; 5. Synchronization of chaotic systems; 6. Detecting synchronization in experiments; Part II. Phase Locking and Frequency Entrainment: 7. Synchronization of periodic oscillators by periodic external action; 8. Mutual synchronization of two interacting periodic oscillators; 9. Synchronization in the presence of noise; 10. Phase synchronization of chaotic systems; 11. Synchronization in oscillatory media; 12. Populations of globally coupled oscillators; Part III. Synchronization of Chaotic Systems: 13. Complete synchronization I: basic concepts; 14. Complete synchronization II: generalizations and complex systems; 15. Synchronization of complex dynamics by external forces; Appendix 1. Discovery of synchronization by Christiaan Huygens; Appendix 2. Instantaneous phase and frequency of a signal; References; Index.
Function projective synchronization in partially linear drive-response chaotic systems
NASA Astrophysics Data System (ADS)
Zhang, Rong; Xu, Zhen-Yuan
2010-12-01
This paper gives the definition of function projective synchronization with less conservative demand for a scaling function, and investigates the function projective synchronization in partially linear drive-response chaotic systems. Based on the Lyapunov stability theory, it has been shown that the function projective synchronization with desired scaling function can be realized by simple control law. Moreover it does not need scaling function to be differentiable, bounded and non-vanished. The numerical simulations are provided to verify the theoretical result.
Remote synchronization of amplitudes across an experimental ring of non-linear oscillators
Minati, Ludovico E-mail: ludovico.minati@unitn.it
2015-12-15
In this paper, the emergence of remote synchronization in a ring of 32 unidirectionally coupled non-linear oscillators is reported. Each oscillator consists of 3 negative voltage gain stages connected in a loop to which two integrators are superimposed and receives input from its preceding neighbour via a “mixing” stage whose gains form the main system control parameters. Collective behaviour of the network is investigated numerically and experimentally, based on a custom-designed circuit board featuring 32 field-programmable analog arrays. A diverse set of synchronization patterns is observed depending on the control parameters. While phase synchronization ensues globally, albeit imperfectly, for certain control parameter values, amplitudes delineate subsets of non-adjacent but preferentially synchronized nodes; this cannot be trivially explained by synchronization paths along sequences of structurally connected nodes and is therefore interpreted as representing a form of remote synchronization. Complex topology of functional synchronization thus emerges from underlying elementary structural connectivity. In addition to the Kuramoto order parameter and cross-correlation coefficient, other synchronization measures are considered, and preliminary findings suggest that generalized synchronization may identify functional relationships across nodes otherwise not visible. Further work elucidating the mechanism underlying this observation of remote synchronization is necessary, to support which experimental data and board design materials have been made freely downloadable.
Remote synchronization of amplitudes across an experimental ring of non-linear oscillators
NASA Astrophysics Data System (ADS)
Minati, Ludovico
2015-12-01
In this paper, the emergence of remote synchronization in a ring of 32 unidirectionally coupled non-linear oscillators is reported. Each oscillator consists of 3 negative voltage gain stages connected in a loop to which two integrators are superimposed and receives input from its preceding neighbour via a "mixing" stage whose gains form the main system control parameters. Collective behaviour of the network is investigated numerically and experimentally, based on a custom-designed circuit board featuring 32 field-programmable analog arrays. A diverse set of synchronization patterns is observed depending on the control parameters. While phase synchronization ensues globally, albeit imperfectly, for certain control parameter values, amplitudes delineate subsets of non-adjacent but preferentially synchronized nodes; this cannot be trivially explained by synchronization paths along sequences of structurally connected nodes and is therefore interpreted as representing a form of remote synchronization. Complex topology of functional synchronization thus emerges from underlying elementary structural connectivity. In addition to the Kuramoto order parameter and cross-correlation coefficient, other synchronization measures are considered, and preliminary findings suggest that generalized synchronization may identify functional relationships across nodes otherwise not visible. Further work elucidating the mechanism underlying this observation of remote synchronization is necessary, to support which experimental data and board design materials have been made freely downloadable.
Non-linear protocell models: synchronization and chaos
NASA Astrophysics Data System (ADS)
Filisetti, A.; Serra, R.; Carletti, T.; Villani, M.; Poli, I.
2010-09-01
We consider generic protocells models allowing linear and non-linear kinetics for the main involved chemical reactions. We are interested in understanding if and how the protocell division and the metabolism do synchronise to give rise to sustainable evolution of the protocell.
Multi-winding homopolar electric machine
Van Neste, Charles W
2012-10-16
A multi-winding homopolar electric machine and method for converting between mechanical energy and electrical energy. The electric machine includes a shaft defining an axis of rotation, first and second magnets, a shielding portion, and a conductor. First and second magnets are coaxial with the shaft and include a charged pole surface and an oppositely charged pole surface, the charged pole surfaces facing one another to form a repulsive field therebetween. The shield portion extends between the magnets to confine at least a portion of the repulsive field to between the first and second magnets. The conductor extends between first and second end contacts and is toroidally coiled about the first and second magnets and the shield portion to develop a voltage across the first and second end contacts in response to rotation of the electric machine about the axis of rotation.
Jeon, W.J.; Katoh, S.; Iwamoto, T.; Kamiya, Y.; Onuki, T.
1999-09-01
This paper treats a novel linear hybrid motor (LHM) by both induction and synchronous operations. The proposed motor consists of one pair of linear synchronous motors (LSMs) and a linear induction motor (LIM). The primary-cores of both LSM and LIM have a common ring winding, and the secondary solid-conductor is arranged in both LIM and the interpole space of LSM. The feature of the motor is that the undesirable vertical force in LSM is offset by the symmetrical double-sided construction and the secondary is capable of self-starting by induction operation. From the investigation by the three-dimensional finite element analysis and experiment, the authors derive an optimal exciting condition for starting, and then verify that the proposed LHM is effective for practical use.
Chaos and Chaos Synchronization of a Symmetric Gyro with Linear-Plus Damping
NASA Astrophysics Data System (ADS)
CHEN, H.-K.
2002-08-01
The dynamic behavior of a symmetric gyro with linear-plus-cubic damping, which is subjected to a harmonic excitation, is studied in this paper. The Liapunov direct method has been used to obtain the sufficient conditions of the stability of the equilibrium points of the system. By applying numerical results, time history, phase diagrams, Poincaré maps, Liapunov exponents and Liapunov dimensions are presented to observe periodic and chaotic motions. Besides, several control methods, the delayed feedback control, the addition of constant motor torque, the addition of period force, and adaptive control algorithm (ACA), have been used to control chaos effectively. Finally, attention is shifted to the synchronization of chaos in the two identical chaotic motions of symmetric gyros. The results show that one can make two identical chaotic systems to synchronize through applying four different kinds of one-way coupling. Furthermore, the synchronization time is also examined.
NASA Astrophysics Data System (ADS)
Suzuki, Kenji; Ishikawa, Atsushi; Dohmeki, Hideo
For short and intermediate distance conveyance using intermittent stator permanent magnet linear synchronous motor (ISPM-LSM), a linear synchronous motor with a short stator (armature) is desirable for increasing the stroke length. A PM-LSM with four poles and three teeth has previously been proposed. However, in the case of few teeth, the generated thrust at the outlet edge decreases and a ripple is produced for the generated thrust. In addition, the generated thrust is affected by the cogging force. This paper discusses the use of an interpole at the stator outlet edge and a method to decrease the thrust ripple. Moreover, a method to decrease the cogging force is also presented.
Reliable clock estimation using linear weighted fusion based on pairwise broadcast synchronization
Shi, Xin Zhao, Xiangmo Hui, Fei Ma, Junyan Yang, Lan
2014-10-06
Clock synchronization in wireless sensor networks (WSNs) has been studied extensively in recent years and many protocols are put forward based on the point of statistical signal processing, which is an effective way to optimize accuracy. However, the accuracy derived from the statistical data can be improved mainly by sufficient packets exchange, which will consume the limited power resources greatly. In this paper, a reliable clock estimation using linear weighted fusion based on pairwise broadcast synchronization is proposed to optimize sync accuracy without expending additional sync packets. As a contribution, a linear weighted fusion scheme for multiple clock deviations is constructed with the collaborative sensing of clock timestamp. And the fusion weight is defined by the covariance of sync errors for different clock deviations. Extensive simulation results show that the proposed approach can achieve better performance in terms of sync overhead and sync accuracy.
Detecting non-linearities in neuro-electrical signals: A study of synchronous local field potentials
NASA Astrophysics Data System (ADS)
Müller-Gerking, Johannes; Martinerie, Jacques; Neuenschwander, Sergio; Pezard, Laurent; Renault, Bernard; Varela, Francisco J.
The question of the presence and detection of non-linear dynamics and possibly low-dimensional chaos in the brain is still an open question, with recent results indicating that initial claims for low dimensionality were faulted by incomplete statistical testing. To make some progress on this question, our approach was to use stringent data analysis of precisely controlled and behaviorally significant neuroelectric data. There are strong indications that functional brain activity is correlated with synchronous local field potentials. We examine here such synchronous episodes in data recorded from the visual system of behaving cats and pigeons. Our purpose was to examine under these ideal conditions whether the time series showed any evidence of non-linearity concommitantly with the arising of synchrony. To test for non-linearity we have used surrogate sets for non-linear forecasting, the false nearest strands method, and an examination of deterministic vs stochastic modeling. Our results indicate that the time series under examination do show evidence for traces of non-linear dynamics but weakly, since they are not robust under changes of parameters. We conclude that low-dimensional chaos is unlikely to be found in the brain, and that a robust detection and characterization of higher-dimensional non-linear dynamics is beyond the reach of current analytical tools.
Analytical modeling of a new disc permanent magnet linear synchronous machine for electric vehicles
Liu, C.T.; Chen, J.W.; Su, K.S.
1999-09-01
This paper develops an analytical approach based on a qd0 reference frame model to analyze dynamic and steady state characteristics of disc permanent magnet linear synchronous machines (DPMLSMs). The established compact mathematical model can be more easily employed to analyze the system behavior and to design the controller. Superiority in operational electromagnetic characteristics of the proposed DPMLSM for electric vehicle (EV) applications is verified by both numerical simulations and experimental investigations.
29-fsec pulse generation from a linear-cavity synchronously pumped dye laser
Kubota, H.; Kurokawa, K.; Nakazawa, M.
1988-09-01
29-fsec optical pulses at a center wavelength of 615 nm have been generated from a linear-cavity synchronously pumped dye laser without using the colliding-pulse mode-locking technique. The laser consists of two dye jets (a gain jet and a saturable absorber jet) and a sequence of four Brewster-angled prisms. Kiton Red S is used as the laser dye instead of the conventional Rhodamine 6G.
High-reluctance rotor rings improve homopolar generator performance
NASA Technical Reports Server (NTRS)
Musset, E. E.
1966-01-01
Nonmagnetic metal rings imbedded in a homopolar generator rotor normal to its axis keep the induction flux entering the rotor in a radial path. Use of the rings permits optimum rotor design for any given set of operating requirements and simplifies the task of predicting the operation characteristics of the generator.
Homopolar Gun for Pulsed Spheromak Fusion Reactors II
Fowler, T
2004-06-14
A homopolar gun is discussed that could produce the high currents required for pulsed spheromak fusion reactors even with unit current amplification and open field lines during injection, possible because close coupling between the gun and flux conserver reduces gun losses to acceptable levels. Example parameters are given for a gun compatible with low cost pulsed reactors and for experiments to develop the concept.
A superconducting homopolar motor and generator—new approaches
NASA Astrophysics Data System (ADS)
Fuger, Rene; Matsekh, Arkadiy; Kells, John; Sercombe, D. B. T.; Guina, Ante
2016-03-01
Homopolar machines were the first continuously running electromechanical converters ever demonstrated but engineering challenges and the rapid development of AC technology prevented wider commercialisation. Recent developments in superconducting, cryogenic and sliding contact technology together with new areas of application have led to a renewed interest in homopolar machines. Some of the advantages of these machines are ripple free constant torque, pure DC operation, high power-to-weight ratio and that rotating magnets or coils are not required. In this paper we present our unique approach to high power and high torque homopolar electromagnetic turbines using specially designed high field superconducting magnets and liquid metal current collectors. The unique arrangement of the superconducting coils delivers a high static drive field as well as effective shielding for the field critical sliding contacts. The novel use of additional shielding coils reduces weight and stray field of the system. Liquid metal current collectors deliver a low resistance, stable and low maintenance sliding contact by using a thin liquid metal layer that fills a circular channel formed by the moving edge of a rotor and surrounded by a conforming stationary channel of the stator. Both technologies are critical to constructing high performance machines. Homopolar machines are pure DC devices that utilise only DC electric and magnetic fields and have no AC losses in the coils or the supporting structure. Guina Energy Technologies has developed, built and tested different motor and generator concepts over the last few years and has combined its experience to develop a new generation of homopolar electromagnetic turbines. This paper summarises the development process, general design parameters and first test results of our high temperature superconducting test motor.
Design and dynamic analysis of permanent magnet linear synchronous machine for servoapplication
NASA Astrophysics Data System (ADS)
Jang, Seok-Myeong; You, Dae-Joon; Jang, Won-Bum; Han, Sang-Chul
2006-04-01
In servosystem demanding precision dynamic characteristics, application of the permanent magnet linear synchronous machines (PMLSMs) has an advantage of analysis convenience by simple geometry and thrust ripple reduction from the sinusoidal back electromotive force and excited stator. Therefore, this paper presents the design of surface-mounted PMLSM with a slotless iron-cored stator according to coil turns to satisfy the rate thrust. Also, from the dynamic analysis for servoapplication of manufactured motor with heavy mass, we offer an accurate range of the dc link voltage and acceleration in rate speed. This is applied to speed reference profile considering the system characteristics in total length of moving position.
Development of High-Force-Density Iron-Core Linear Synchronous Motor
NASA Astrophysics Data System (ADS)
Kakihara, Masanobu; Hoshi, Toshiyuki; Shikayama, Toru; Ohto, Motomichi
The demand for small-sized and high-acceleration linear motors for industrial machines such as semiconductor production equipment and LCD equipment is rapidly increasing in order to maintain the small size of these equipment and to increase productivity. To satisfy the demand, high-force-density (i.e., force per volume) linear motors are required. This paper discusses the development of a high-force-density iron-core linear synchronous motor that consists of a Halbach magnet array with soft magnetic material and a grain-oriented silicon steel sheet core; the motor has a shape-optimized design. The motor constant square density of the new linear motor reaches 10N2/W/cm3, while that of the highest force linear motor available at present is 5N2/W/cm3. In other words, the new motor can deliver a force of 900N per 1000cm3. In this paper, details of the design, especially the structure and performance of the new motor are presented, and the design is validated on the basis of measurements of a prototype motor.
NASA Astrophysics Data System (ADS)
Meng, Fanwei; Liu, Chengying; Li, Zhijun; Wang, Liping
2013-01-01
Due to low damping ratio, flat permanent magnet linear synchronous motor's vibration is difficult to be damped and the accuracy is limited. The vibration suppressing results are not good enough in the existing research because only the longitudinal direction vibration is considered while the normal direction vibration is neglected. The parameters of the direct-axis current controller are set to be the same as those of the quadrature-axis current controller commonly. This causes contradiction between signal noise and response. To suppress the vibration, the electromagnetic force model of the flat permanent magnet synchronous linear motor is formulated first. Through the analysis of the effect that direct-axis current noise and quadrature-axis current noise have on both direction vibration, it can be declared that the conclusion that longitudinal direction vibration is only related to the quadrature-axis current noise while the normal direction vibration is related to both the quadrature-axis current noise and direct-axis current noise. Then, the simulation test on current loop with a low-pass filter is conducted and the results show that the low-pass filter can not suppress the vibration but makes the vibration more severe. So a vibration suppressing strategy that the proportional gain of direct-axis current controller adapted according to quadrature-axis reference current is proposed. This control strategy can suppress motor vibration by suppressing direct-axis current noise. The experiments results about the effect of K p and T i on normal direction vibration, longitudinal vibration and the position step response show that this strategy suppresses vibration effectively while the motor's motion performance is not affected. The maximum reduction of vibration can be up to 40%. In addition, current test under rated load condition is also conducted and the results show that the control strategy can avoid the conflict between the direct-axis current and the quadrature
Liu, Xiwei; Chen, Tianping
2015-10-01
In this paper, we investigate the exponential synchronization problem for linearly coupled networks with delay by pinning a simple aperiodically intermittent controller. The network topology can be directed. Different from previous works, the intermittent control can be aperiodic. Two types of delay are considered. The first case is that the delay is time-varying and large, and in this case, there is no restriction imposed on the delay and the control (and/or rest) width. The other one is that the delay is small enough so that it is less than the minimum of control width. Different approaches are provided to investigate these two cases, and some criteria are given to realize exponential synchronization. Furthermore, by applying the adaptive approach to the second model, we establish a general adaptive theory for intermittent control, which can be applied not only to networks without time delay, but also to delayed networks, regardless of whether the intermittent control is periodic or aperiodic. Finally, the numerical simulations are given to verify the validness of the theoretical results. PMID:25576584
NASA Astrophysics Data System (ADS)
Zhu, Yu-wu; Kim, Do-sun; Cho, Yun-hyun
2007-12-01
The problem in improving the high positioning precision of permanent magnet linear synchronous motor (PMLSM) for direct drive conveyer is the large detent force, which contains two components: one is the cogging force caused by the interaction between the permanent magnet (PM) and the iron core, the other is the end effect caused by the finite mover length. In this paper a force compensator in the field oriented control (FOC) algorithm is employed to reduce this detent force, so the thrust and the normal force characteristics analysis of PMLSM are of the most importance. First the characteristics of the thrust and the normal force are simulated by finite element method (FEM), and the relation of the thrust and the normal force to the q-axis current is analyzed. Then the components of detent force are defined by Fourier series using the curve fitting method, and compensated by injecting the instantaneous currents using the FOC method. Finally the dynamic characteristics of this PMLSM for direct drive conveyer are investigated, and the numerical results are reported to validate the effectiveness of this proposed method.
Compact homopolar generator developed at CEM-UT
NASA Astrophysics Data System (ADS)
Gully, J. H.; Estes, E. G.; Walls, W. A.; Weldon, W. F.
1984-03-01
Attention is given to a project concerned with the development of a field-portable electromagnetic launcher (EML) system. The initial step in this project involved the design, the fabrication, and test of a prototype homopolar generator (HPG). One of these machines will drive an 85-g projectile to 3 km/s in a 4-m gun, or a 10-g projectile to 10 km/s in a 5.5-m gun. The prototype compact HPG is considered along with auxiliary systems, the HPG systems tester, and experiments. The HPG system tester has been built and used to develop components needed to further improve the HPG's performance and energy density. Faster spinning of the HPG rotor is the most direct method of improving energy density.
NASA Astrophysics Data System (ADS)
Yoshida, K.; Matsumoto, H.
2003-10-01
We have proposed a new linear synchronous motor (LSM) theory which is based on an idea of considering the pinning force as synchronizing one in using current-carrying-armature-winding instead of permanent magnets. We have carried out basic experiments on two-dimensional electromagnetic forces produced in HTS bulk within DC-magnetic-field. As a result, we found that HTS bulk magnet in a cooling case can be levitated and guided stably according to the flux conditions between bulk and DC magnet. HTS bulk LSM can produce propulsion, levitation and guidance forces from zero speed, and be used in many applications. This paper proposes HTS bulk LSM analyzed and designed taking into account E- J characteristic. The LSM can produce stable guidance force without control. The LSM propulsion and guidance motion can be simulated numerically only by a simple propulsion control, which is not only closed-loop control but also open-loop control.
NASA Astrophysics Data System (ADS)
Krop, D. C. J.; Lomonova, E. A.; Jansen, J. W.; Paulides, J. J. H.
2009-04-01
Linear motors find their utilization in an increasing number of industrial applications. Permanent magnet linear synchronous motors (PMLSMs) are favorable in many applications due to their servo characteristics, robustness, and high force density. The major disadvantage of moving coil type PMLSMs is the cable slab that energizes the coils from the fixed world to the moving parts of the machine. These cable slabs introduce extra wear and dynamical distortions. Moreover, in precision application the cable slab is supported by additional linear drives. These disadvantages can be eliminated if the coils could be powered wirelessly. In this paper two topologies are proposed that are capable of transferring 1 kW of power at most. The transformer part of the CET is characterized by means of two dimensional finite element analysis, and the influence of using additional capacitors to boost the output power is examined. Furthermore, an analysis of the core losses is conducted. Conclusions are drawn from the results.
Homopolar machine for reversible energy storage and transfer systems
Stillwagon, Roy E.
1981-01-01
A homopolar machine designed to operate as a generator and motor in reversibly storing and transferring energy between the machine and a magnetic load coil for a thermo-nuclear reactor. The machine rotor comprises hollow thin-walled cylinders or sleeves which form the basis of the system by utilizing substantially all of the rotor mass as a conductor thus making it possible to transfer substantially all the rotor kinetic energy electrically to the load coil in a highly economical and efficient manner. The rotor is divided into multiple separate cylinders or sleeves of modular design, connected in series and arranged to rotate in opposite directions but maintain the supply of current in a single direction to the machine terminals. A stator concentrically disposed around the sleeves consists of a hollow cylinder having a number of excitation coils each located radially outward from the ends of adjacent sleeves. Current collected at an end of each sleeve by sleeve slip rings and brushes is transferred through terminals to the magnetic load coil. Thereafter, electrical energy returned from the coil then flows through the machine which causes the sleeves to motor up to the desired speed in preparation for repetition of the cycle. To eliminate drag on the rotor between current pulses, the brush rigging is designed to lift brushes from all slip rings in the machine.
Homopolar machine for reversible energy storage and transfer systems
Stillwagon, Roy E.
1978-01-01
A homopolar machine designed to operate as a generator and motor in reversibly storing and transferring energy between the machine and a magnetic load coil for a thermo-nuclear reactor. The machine rotor comprises hollow thin-walled cylinders or sleeves which form the basis of the system by utilizing substantially all of the rotor mass as a conductor thus making it possible to transfer substantially all the rotor kinetic energy electrically to the load coil in a highly economical and efficient manner. The rotor is divided into multiple separate cylinders or sleeves of modular design, connected in series and arranged to rotate in opposite directions but maintain the supply of current in a single direction to the machine terminals. A stator concentrically disposed around the sleeves consists of a hollow cylinder having a number of excitation coils each located radially outward from the ends of adjacent sleeves. Current collected at an end of each sleeve by sleeve slip rings and brushes is transferred through terminals to the magnetic load coil. Thereafter, electrical energy returned from the coil then flows through the machine which causes the sleeves to motor up to the desired speed in preparation for repetition of the cycle. To eliminate drag on the rotor between current pulses, the brush rigging is designed to lift brushes from all slip rings in the machine.
Partial synchronization in networks of non-linearly coupled oscillators: The Deserter Hubs Model
NASA Astrophysics Data System (ADS)
Freitas, Celso; Macau, Elbert; Pikovsky, Arkady
2015-04-01
We study the Deserter Hubs Model: a Kuramoto-like model of coupled identical phase oscillators on a network, where attractive and repulsive couplings are balanced dynamically due to nonlinearity of interactions. Under weak force, an oscillator tends to follow the phase of its neighbors, but if an oscillator is compelled to follow its peers by a sufficient large number of cohesive neighbors, then it actually starts to act in the opposite manner, i.e., in anti-phase with the majority. Analytic results yield that if the repulsion parameter is small enough in comparison with the degree of the maximum hub, then the full synchronization state is locally stable. Numerical experiments are performed to explore the model beyond this threshold, where the overall cohesion is lost. We report in detail partially synchronous dynamical regimes, like stationary phase-locking, multistability, periodic and chaotic states. Via statistical analysis of different network organizations like tree, scale-free, and random ones, we found a measure allowing one to predict relative abundance of partially synchronous stationary states in comparison to time-dependent ones.
Partial synchronization in networks of non-linearly coupled oscillators: The Deserter Hubs Model
Freitas, Celso Macau, Elbert; Pikovsky, Arkady
2015-04-15
We study the Deserter Hubs Model: a Kuramoto-like model of coupled identical phase oscillators on a network, where attractive and repulsive couplings are balanced dynamically due to nonlinearity of interactions. Under weak force, an oscillator tends to follow the phase of its neighbors, but if an oscillator is compelled to follow its peers by a sufficient large number of cohesive neighbors, then it actually starts to act in the opposite manner, i.e., in anti-phase with the majority. Analytic results yield that if the repulsion parameter is small enough in comparison with the degree of the maximum hub, then the full synchronization state is locally stable. Numerical experiments are performed to explore the model beyond this threshold, where the overall cohesion is lost. We report in detail partially synchronous dynamical regimes, like stationary phase-locking, multistability, periodic and chaotic states. Via statistical analysis of different network organizations like tree, scale-free, and random ones, we found a measure allowing one to predict relative abundance of partially synchronous stationary states in comparison to time-dependent ones.
NASA Astrophysics Data System (ADS)
Pina, J. M.; Neves, M. V.; McCulloch, M. D.; Rodrigues, A. L.
2006-06-01
The high diamagnetism observed in high temperature superconducting (HTS) materials lead to applications involving levitation such as the linear synchronous motor (LSM). Certain features taken into account in conventional LSM design cannot be applied in the HTS case, due to these materials characteristics, such as BSCCO stiffness, when used as armature windings. Also other design features, e.g. slot skewing, which reduces the space harmonics of the air gap magnetic flux density, thus influencing motor performance, plays an important role in final cost. These and other aspects such as the thrust force or the effect of motor control through an inverter are examined in this paper, where the analytical and numerical methodologies involved in the design optimisation of a LSM demonstrator with premagnetised YBCO pellets in the field excitation system and BSCCO armature windings are described. Simulation results are also included.
NASA Astrophysics Data System (ADS)
Yen, F.; Li, J.; Zheng, S. J.; Liu, L.; Ma, G. T.; Wang, J. S.; Wang, S. Y.; Liu, Wei
2010-10-01
Thrust measurements were performed on a coil made of a YBa2Cu3O7 - δ coated conductor acting as the excitation system of a single-sided linear synchronous motor. The superconducting coil was a single pancake in the shape of a racetrack with 100 turns, the width and effective lengths were 42 mm and 84 mm, respectively. The stator was made of conventional copper wire. At 77 K and a gap of 10 mm, with an operating direct current of IDC = 30 A for the superconducting coil and alternating current of IAC = 9 A for the stator coils, a thrust of 24 N was achieved. With addition of an iron core, thrust was increased by 49%. With addition of an iron back-plate, thrust was increased by 70%.
Design of a superconducting linear synchronous motor with YBCO coil magnet
NASA Astrophysics Data System (ADS)
Li, Jing; Tang, Junjie; Zhang, Ya
2015-09-01
The forces of the flat single-sided linear motor with four superconducting coils on the excitation system were presented by experimental method. The influences of the coil height and number of turns on the forces were investigated by the simulation method. Although the maximum thrust increased monotonically with the value of turns, the corresponding increment of the thrust decreased with the value of turns. The thrust reaches a certain saturation value with increasing the height of the superconducting coil. Continuing to increase the height of the coil could lead to an increase of the normal force. The superconducting linear motor is finally designed with the capability to generate thrust of 1 kN/m.
NASA Astrophysics Data System (ADS)
Hirayama, Tadashi; Higuchi, Tsuyoshi
In a previous paper, we proposed a novel linear synchronous motor with half-wave-rectified self-excitation. The long-stator-type linear synchronous motor was built, and its performance was verified by performing experiments. This paper presents a new current control method for the linear synchronous motor for achieving a wide range of speeds and high-power operations. First, we propose the current control method for high-thrust operation in the constant-thrust region. This operation is realized by using a reluctance thrust resulting from the saliency of the linear synchronous motor. Furthermore, we propose a control method that maximizes the ratio of the thrust to the voltage; this method can be used to expand the operating range. Wide-range-speed operation can be achieved by applying this new control method along with field-weakening control. The thrust and operation characteristics of the proposed control methods are estimated by performing experiments and an electric and magnetic coupled analysis.
NASA Astrophysics Data System (ADS)
Eom, Beomyong; Lee, Changhyeong; Kim, Seokho; Lee, Changyoung; Yun, Sangwon
The existing wheel-type high-speed railway with a rotatable motor has a limit of 600 km/h speed. The normal conducting electromagnet has several disadvantages to realize 600 km/h speed. Several disadvantages are the increased space and weight, and the decreased electric efficiency to generate the required high magnetic field. In order to reduce the volume and weight, superconducting electromagnets can be considered for LSM (Linear Synchronous Motor). Prior to the fabrication of the real system, a prototype demo-coil is designed and fabricated using 2G high temperature superconducting wire. The prototype HTS coil is cooled by the conduction using a GM cryocooler. To reduce the heat penetration, thermal design was performed for the current leads, supporting structure and radiation shield considering the thermal stress. The operating temperature and current are 30∼40 K and 100 A. The coil consists of two double pancake coils (N, S pole, respectively) and it is driven on a test rail, which is installed for the test car. This paper describes the design and test results of the prototype HTS LSM system. Thermal characteristics are investigated with additional dummy thermal mass on the coil after turning off the cryocooler.
Development of a current collection loss management system for SDI homopolar power supplies
Brown, D.W.
1989-01-01
High speed, high power density current collection systems have been identified as an enabling technology required to construct homopolar power supplies to meet SDI missions. This work is part of a three-year effort directed towards the analysis, experimental verification, and prototype construction of a current collection system designed to operate continuously at 2 kA/cm{sup 2}, at a rubbing speed of 200 m/s, and with acceptable losses in a space environment. To data, no system has achieved these conditions simultaneously. This is the annual report covering the second year period of performance on DOE contract DE-AC03-86SF16518. Major areas covered include design, construction and operation of a cryogenically cooled brush test rig, design and construction of a high speed brush test rig, optimization study for homopolar machines, loss analysis of the current collection system, and an application study which defines the air-core homopolar construction necessary to achieve the goal of 80--90 kW/kg generator power density. 17 figs., 2 tabs.
NASA Astrophysics Data System (ADS)
Jang, Seok-Myeong; You, Dae-Joon; Jang, Won-Bum; Park, Ji-Hoon
2005-05-01
This paper presents the practical parameter estimation for a slotless air-cored permanent magnet linear synchronous motor (PMLSM) using an analytical method and experiment. In the analytical method, the linkage flux is calculated through the generalized magnetic vector potential obtained by the space harmonics and transfer relation with each region of permanent magnet (PM) mover, air gap, and winding stator. This linkage flux is used to estimate the dynamic parameters such as magnetization inductance, backemf, and thrust constant. Also, the resistance and self-inductance with one phase are obtained by the experiment. Therefore, dynamic simulation of a linear synchronous motor composed of dynamic parameters is performed by the nonrotating (d-q) voltage equation. In good agreement with the estimated parameter values, the experimental results confirm the validity of the analysis method and simulation.
NASA Astrophysics Data System (ADS)
Štumberger, Gorazd; Štumberger, Bojan; Dolinar, Drago
2006-09-01
This paper analyses the impact of armature slotting and magnetically nonlinear and anisotropic iron core on the trajectories of a kinematically controlled linear synchronous reluctance motor (LSRM). A new magnetically nonlinear dynamic two-axis LSRM model is introduced in order to perform the analysis. The magnetic nonlinearities and slotting effects are accounted for by the current and position-dependent characteristics of flux linkages.
Liang, Hongjing; Zhang, Huaguang; Wang, Zhanshan
2015-11-01
This paper considers output synchronization of discrete-time multi-agent systems with directed communication topologies. The directed communication graph contains a spanning tree and the exosystem as its root. Distributed observer-based consensus protocols are proposed, based on the relative outputs of neighboring agents. A multi-step algorithm is presented to construct the observer-based protocols. In light of the discrete-time algebraic Riccati equation and internal model principle, synchronization problem is completed. At last, numerical simulation is provided to verify the effectiveness of the theoretical results. PMID:26365366
A new two-phase homopolar switched reluctance motor for electric vehicle applications
NASA Astrophysics Data System (ADS)
Tsai, Mi-Ching; Huang, Chien-Chin; Huang, Zheng-Yi
2003-12-01
This paper presents a novel 2-phase homopolar switched reluctance motor (SRM), whose design successfully avoids dead-zone problems that afflict low cost 1- and/or 2-phase SRMs. Unlike conventional radial-winding-radial-gap motors, the proposed SRM has an interior stator that is of the pancake type with axial winding. Such a design allows for a high slot-fill factor and is suitable for implementation as a flat pancake-shaped stator. An efficient, compact prototype was produced with TMS320F240 DSP driving control unit. Experimental results indicate that the present SRM design has the potential to be used for electric bicycles and scooters.
Clearance sensing hydrostatic bearing restrictor for the homopolar generator systems tester
Vaughn, M.R.
1985-01-01
This work documents the development of an advanced hydrostatic bearing system for the subcritical operation of the Homopolar Generator Systems Tester. Since this Systems Tester is unique in that it was built with stationary shaft bearings, several new hydrostatic bearing ideas were developed. First, a new clearance sensing variable restrictor was developed to accommodate the almost five fold increase in radial bearing clearance intrinsic to the machine geometry encountered during each machine cycle. A new dynamic hydrostatic thrust-bearing model was developed that permits tilt about any axis perpendicular to the axis of rotation as well as axial motion. These bearings are well instrumented providing data to verify the models both at rest and during operation. In addition to the bearing advances, overall machine design decisions, as well as the factors which influenced them, are examined. Magnetic effects are discussed with respect to both rotor dynamic effects and thrust bearing loading. Bearing sump and sealing philosophies are also discussed. Decisions concerning rotor geometry are similarly reviewed. Finally, the results of the experiment are evaluated in terms of the future impact on not only homopolar generators, but on rotating machinery in general.
Low loss pole configuration for multi-pole homopolar magnetic bearings
NASA Technical Reports Server (NTRS)
Blumenstock, Kenneth A. (Inventor); Hakun, Claef F. (Inventor)
2001-01-01
A new pole configuration for multi-pole homopolar bearings proposed in this invention reduces rotational losses caused by eddy-currents generated when non-uniform flux distributions exist along the rotor surfaces. The new homopolar magnetic bearing includes a stator with reduced pole-to-pole and exhibits a much more uniform rotor flux than with large pole-to-pole gaps. A pole feature called a pole-link is incorporated into the low-loss poles to provide a uniform pole-to-pole gap and a controlled path for pole-to-pole flux. In order to implement the low-loss pole configuration of magnetic bearings with small pole-to-pole gaps, a new stator configuration was developed to facilitate installation of coil windings. The stator was divided into sector shaped pieces, as many pieces as there are poles. Each sector-shaped pole-piece can be wound on a standard coil winding machine, and it is practical to wind precision layer wound coils. To achieve maximum actuation efficiency, it is desirable to use all the available space for the coil formed by the natural geometric configuration. Then, the coils can be wound in a tapered shape. After winding, the sectored-pole-pieces are installed into and fastened by bonding or other means, to a ring of material which encloses the sectored-pole-pieces, forming a complete stator.
Development of a current collection loss management system for SDI homopolar power supplies
Hannan, W.F. III.
1987-01-01
High speed, high power density current collection systems have been identified as an enabling technology required to construct homopolar power supplies to meet SDI missions. This work is part of a three-year effort directed towards the analysis, experimental verification, and prototype construction of a current collection system designed to operated continuously at 2 kA/cm{sup 2}, at a rubbing speed of 200 m/s, and with acceptable losses in a space environment. To data, no system has achieved these conditions simultaneously. This is the annual report covering the first year period of performance on DOE contract DE-AC03-86SF16518. Major areas covered include design and construction of a cryogenically-cooled brush test rig, design of a high speed brush test rig, loss analysis of the current collection system, and an application study which defines the air core homopolar construction necessary to achieve the goal of 80--90 kW/kg generator power density. 15 figs.
Homopolar bonds in Se-rich Ge‒As‒Se chalcogenide glasses
NASA Astrophysics Data System (ADS)
Si-Wei, Xu; Rong-Ping, Wang; Zhi-Yong, Yang; Li, Wang; Luther-Davies, Barry
2016-05-01
We have prepared three groups of Ge–As–Se glasses in which the Se content is 5.5 mol%, 10 mol%, and 20 mol% rich, respectively. We explored the possibility of suppressing the formation of the Ge–Ge and As–As homopolar bonds in the glasses. Thermal kinetics analysis indicated that the 5.5 mol% Se-rich Ge11.5As24Se64.5 glass exhibits the minimum fragility and thus is most stable against structural relaxation. Analysis of the Raman spectra of the glasses indicated that the Ge–Ge and As–As homopolar bonds could be almost completely suppressed in 20 mol% Se-rich Ge15As14Se71 glass. Project supported by the Australian Research Council (ARC) Centre of Excellence for Ultrahigh Bandwidth Device for Optical System (Project CE110001018), Australian Research Council Discovery Programs (Project DP110102753), and the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions, China.
NASA Astrophysics Data System (ADS)
Murillo Pulgarín, J. A.; Alañón Molina, A.; Boras, N.
2012-12-01
Synchronous fluorescence spectroscopy (SFS) is a rapid, sensitive and non-destructive method suitable for the analysis of multifluorophoric mixtures. In this study non linear variable angle synchronous spectrofluorimetry was applied to the determination of three fluoroquinololes in urine. Although this technique provides very good results, total resolution of multicomponent mixtures is not always achieved when the spectral profiles strongly overlap. Partial least-squares regression (PLS-1) was utilized to a develop calibration model that related synchronous fluorescence spectra to the analytical concentration of fluoroquinolones in the presence of urine. The same multicomponent mixture was determined using excitation emission matrix fluorescence (EEMF) along with N-way partial least squares regression (N-PLS and U-PLS). The determination was carried out in micellar medium 0.01 M with a pH of 4.8 provided by 0.2 M sodium acetate/acetic acid buffer. A central composite design was selected to obtain a calibration matrix of 25 standards plus a blank sample. The proposed methods were validated by application to a test set of synthetic samples. The results show that SFS with PLS-1 is a better method compared to EEMF with N-PLS or U-PLS because of the low RMSEP values of the former.
Synchronicity from synchronized chaos
Duane, Gregory
2015-04-01
The synchronization of loosely-coupled chaotic oscillators, a phenomenon investigated intensively for the last two decades, may realize the philosophical concept of “synchronicity”—the commonplace notion that related events mysteriously occur at the same time. When extended to continuous media and/or large discrete arrays, and when general (non-identical) correspondences are considered between states, intermittent synchronous relationships indeed become ubiquitous. Meaningful synchronicity follows naturally if meaningful events are identified with coherent structures, defined by internal synchronization between remote degrees of freedom; a condition that has been posited as necessary for synchronizability with an external system. The important case of synchronization between mind and matter is realized if mind is analogized to a computer model, synchronizing with a sporadically observed system, as in meteorological data assimilation. Evidence for the ubiquity of synchronization is reviewed along with recent proposals that: (1) synchronization of different models of the same objective process may be an expeditious route to improved computational modeling and may also describe the functioning of conscious brains; and (2) the nonlocality in quantum phenomena implied by Bell’s theorem may be explained in a variety of deterministic (hidden variable) interpretations if the quantum world resides on a generalized synchronization “manifold”.
Synchronicity from synchronized chaos
Duane, Gregory
2015-04-01
The synchronization of loosely-coupled chaotic oscillators, a phenomenon investigated intensively for the last two decades, may realize the philosophical concept of “synchronicity”—the commonplace notion that related events mysteriously occur at the same time. When extended to continuous media and/or large discrete arrays, and when general (non-identical) correspondences are considered between states, intermittent synchronous relationships indeed become ubiquitous. Meaningful synchronicity follows naturally if meaningful events are identified with coherent structures, defined by internal synchronization between remote degrees of freedom; a condition that has been posited as necessary for synchronizability with an external system. The important case of synchronization between mind andmore » matter is realized if mind is analogized to a computer model, synchronizing with a sporadically observed system, as in meteorological data assimilation. Evidence for the ubiquity of synchronization is reviewed along with recent proposals that: (1) synchronization of different models of the same objective process may be an expeditious route to improved computational modeling and may also describe the functioning of conscious brains; and (2) the nonlocality in quantum phenomena implied by Bell’s theorem may be explained in a variety of deterministic (hidden variable) interpretations if the quantum world resides on a generalized synchronization “manifold”.« less
NASA Astrophysics Data System (ADS)
Şeker, Murat; Zergeroğlu, Erkan; Tatlicioğlu, Enver
2016-01-01
In this study, a robust backstepping approach for the control problem of the variable-speed wind turbine with a permanent magnet synchronous generator is presented. Specifically, to overcome the negative effects of parametric uncertainties in both mechanical and electrical subsystems, a robust controller with a differentiable compensation term is proposed. The proposed methodology ensures the generator velocity tracking error to uniformly approach a small bound where practical tracking is achieved. Stability of the overall system is ensured by Lyapunov-based arguments. Comparative simulation studies with a standard proportional-integral-type controller are performed to illustrate the effectiveness, feasibility and efficiency of the proposed controller.
High Temperature, Permanent Magnet Biased, Fault Tolerant, Homopolar Magnetic Bearing Development
NASA Technical Reports Server (NTRS)
Palazzolo, Alan; Tucker, Randall; Kenny, Andrew; Kang, Kyung-Dae; Ghandi, Varun; Liu, Jinfang; Choi, Heeju; Provenza, Andrew
2008-01-01
This paper summarizes the development of a magnetic bearing designed to operate at 1,000 F. A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1,000 F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces with over one-half of the coils failed. The construction and design methodology of the bearing is outlined and test results are shown. The agreement between a 3D finite element, magnetic field based prediction for force is shown to be in good agreement with predictions at room and high temperature. A 5 axis test rig will be complete soon to provide a means to test the magnetic bearings at high temperature and speed.
NASA Astrophysics Data System (ADS)
Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo
2016-05-01
In this paper, phase and speed synchronization control of four eccentric rotors (ERs) driven by induction motors in a linear vibratory feeder with unknown time-varying load torques is studied. Firstly, the electromechanical coupling model of the linear vibratory feeder is established by associating induction motor's model with the dynamic model of the system, which is a typical under actuated model. According to the characteristics of the linear vibratory feeder, the complex control problem of the under actuated electromechanical coupling model converts to phase and speed synchronization control of four ERs. In order to keep the four ERs operating synchronously with zero phase differences, phase and speed synchronization controllers are designed by employing adaptive sliding mode control (ASMC) algorithm via a modified master-slave structure. The stability of the controllers is proved by Lyapunov stability theorem. The proposed controllers are verified by simulation via Matlab/Simulink program and compared with the conventional sliding mode control (SMC) algorithm. The results show the proposed controllers can reject the time-varying load torques effectively and four ERs can operate synchronously with zero phase differences. Moreover, the control performance is better than the conventional SMC algorithm and the chattering phenomenon is attenuated. Furthermore, the effects of reference speed and parametric perturbations are discussed to show the strong robustness of the proposed controllers. Finally, experiments on a simple vibratory test bench are operated by using the proposed controllers and without control, respectively, to validate the effectiveness of the proposed controllers further.
NASA Astrophysics Data System (ADS)
Hide, Raymond
1997-02-01
This paper discusses the derivation of the autonomous sets of dimensionless nonlinear ordinary differential equations (ODE's) that govern the behaviour of a hierarchy of related electro-mechanical self-exciting Faraday-disk homopolar dynamo systems driven by steady mechanical couples. Each system comprises N interacting units which could be arranged in a ring or lattice. Within each unit and connected in parallel or in series with the coil are electric motors driven into motion by the dynamo, all having linear characteristics, so that nonlinearity arises entirely through the coupling between components. By introducing simple extra terms into the equations it is possible to represent biasing effects arising from impressed electromotive forces due to thermoelectric or chemical processes and from the presence of ambient magnetic fields. Dissipation in the system is due not only to ohmic heating but also to mechanical friction in the disk and the motors, with the latter agency, no matter how weak, playing an unexpectedly crucial rôle in the production of régimes of chaotic behaviour. This has already been demonstrated in recent work on a case of a single unit incorporating just one series motor, which is governed by a novel autonomous set of nonlinear ODE's with three time-dependent variables and four control parameters. It will be of mathematical as well as geophysical and astrophysical interest to investigate systematically phase and amplitude locking and other types of behaviour in the more complicated cases that arise when N > 1, which can typically involve up to 6 N dependent variables and 19 N-5 control parameters. Even the simplest members of the hierarchy, with N as low as 1, 2 or 3, could prove useful as physically-realistic low-dimensional models in theoretical studies of fluctuating stellar and planetary magnetic fields. Geomagnetic polarity reversals could be affected by the presence of the Earth's solid metallic inner core, driven like an electric motor
NASA Technical Reports Server (NTRS)
Sorensen, Ira J.
1998-01-01
The Thermal Radiation Group, a laboratory in the department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently working towards the development of a new technology for cavity-based radiometers. The radiometer consists of a 256-element linear-array thermopile detector mounted on the wall of a mirrored wedgeshaped cavity. The objective of this research is to provide analytical and experimental characterization of the proposed radiometer. A dynamic end-to-end opto-electrothermal model is developed to simulate the performance of the radiometer. Experimental results for prototype thermopile detectors are included. Also presented is the concept of the discrete Green's function to characterize the optical scattering of radiant energy in the cavity, along with a data-processing algorithm to correct for the scattering. Finally, a parametric study of the sensitivity of the discrete Green's function to uncertainties in the surface properties of the cavity is presented.
Minati, Ludovico E-mail: ludovico.minati@unitn.it
2015-03-15
In this paper, the topographical relationship between functional connectivity (intended as inter-regional synchronization), spectral and non-linear dynamical properties across cortical areas of the healthy human brain is considered. Based upon functional MRI acquisitions of spontaneous activity during wakeful idleness, node degree maps are determined by thresholding the temporal correlation coefficient among all voxel pairs. In addition, for individual voxel time-series, the relative amplitude of low-frequency fluctuations and the correlation dimension (D{sub 2}), determined with respect to Fourier amplitude and value distribution matched surrogate data, are measured. Across cortical areas, high node degree is associated with a shift towards lower frequency activity and, compared to surrogate data, clearer saturation to a lower correlation dimension, suggesting presence of non-linear structure. An attempt to recapitulate this relationship in a network of single-transistor oscillators is made, based on a diffusive ring (n = 90) with added long-distance links defining four extended hub regions. Similarly to the brain data, it is found that oscillators in the hub regions generate signals with larger low-frequency cycle amplitude fluctuations and clearer saturation to a lower correlation dimension compared to surrogates. The effect emerges more markedly close to criticality. The homology observed between the two systems despite profound differences in scale, coupling mechanism and dynamics appears noteworthy. These experimental results motivate further investigation into the heterogeneity of cortical non-linear dynamics in relation to connectivity and underline the ability for small networks of single-transistor oscillators to recreate collective phenomena arising in much more complex biological systems, potentially representing a future platform for modelling disease-related changes.
Calimag-Williams, Korina; Knobel, Gaston; Goicoechea, H C; Campiglia, A D
2014-02-01
An attractive approach to handle matrix interference in samples of unknown composition is to generate second- or higher-order data formats and process them with appropriate chemometric algorithms. Several strategies exist to generate high-order data in fluorescence spectroscopy, including wavelength time matrices, excitation-emission matrices and time-resolved excitation-emission matrices. This article tackles a different aspect of generating high-order fluorescence data as it focuses on total synchronous fluorescence spectroscopy. This approach refers to recording synchronous fluorescence spectra at various wavelength offsets. Analogous to the concept of an excitation-emission data format, total synchronous data arrays fit into the category of second-order data. The main difference between them is the non-bilinear behavior of synchronous fluorescence data. Synchronous spectral profiles change with the wavelength offset used for sample excitation. The work presented here reports the first application of total synchronous fluorescence spectroscopy to the analysis of monohydroxy-polycyclic aromatic hydrocarbons in urine samples of unknown composition. Matrix interference is appropriately handled by processing the data either with unfolded-partial least squares and multi-way partial least squares, both followed by residual bi-linearization. PMID:24456595
Avoided Crossing and Synchronization
NASA Astrophysics Data System (ADS)
Sekii, T.; Shibahashi, H.
2013-12-01
We examine avoided crossing of stellar pulsations in the nonlinear regime, where synchronization may occur, based on a simple model of weakly coupled van der Pol oscillators with close frequencies. For this simple case, avoided crossing is unaffected in the sense that there is a frequency difference between the symmetric and antisymmetric modes, but as a result of synchronization, unlike the linear oscillations case, the system can vibrate in only one of the modes.
NASA Astrophysics Data System (ADS)
Hildenbrand, D. J.; Pichot, M. A.; Price, J. H.
1986-11-01
Design criteria and features of a 60 MJ pulse power supply to be operated at the Center for Electromechanics at the University of Texas are described. The system is driven by six 10 MJ homopolar generators (HPG) which can be operated in series, in parallel, or in combination configurations. Component modularity, operational dependability, repetition rate, maintainability, drive train simplicity and failsafe operation criteria were met in the final design. The generators have removable brush assemblies and water cooled field coil assemblies and hydrostatic bearings. A block diagram is provided of the control I-O architecture and back-up systems and operational procedures are outlined.
NASA Technical Reports Server (NTRS)
Brown, G. V.; Dirusso, E.; Provenza, A. J.
1995-01-01
A proof-of-feasibility demonstration showed that high temperature superconductor (HTS) coils can be used in a high-load, active magnetic bearing in liquid nitrogen. A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 200 lb (890 N) radial load capacity (measured non-rotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that in Cu in liquid nitrogen. Design compromises permitted use of circular coils with rectangular cross section. Conductor improvements will eventually permit coil shape optimization, higher current density and higher bearing load capacity. The bias coil, wound with non-twisted, multifilament HTS conductor, required negligible power to carry its direct current. The control coils were wound with monofilament HTS sheathed in Ag. These dissipated negligible power for direct current (i.e. for steady radial load components). When an alternating current (AC) was added, the AC component dissipated power which increased rapidly with frequency and quadratically with AC amplitude. In fact at frequencies above about 2 hz, the effective resistance of the control coil conductor actually exceeds that of the silver which is in electrical parallel with the oxide superconductor. This is at least qualitatively understandable in the context of a Bean-type model of flux and current penetration into a Type II superconductor. Fortunately the dynamic currents required for bearing stability are of small amplitude. These results show that while twisted multifilament conductor is not needed for stable levitation, twisted multifilaments will be required to reduce control power for sizable dynamic loads, such as those due to unbalance.
Global Synchronization of a New Chua's System
NASA Astrophysics Data System (ADS)
Zhou, Guopeng; Liu, Di; Huang, Jinhua; Liao, Xiaoxin
The problem of global synchronization control for a class of new Chua's system is studied in this paper. Several linear controllers are proposed to realize the global exponential synchronization of two Chua's systems. Decoupling feedback control method is used to make Chua's system global exponential synchronized. Global exponential synchronization with respect to (w.r.t) partial state variables is studied when one of the error variables is zero. Finally, an adaptive synchronization controller is designed to make the response and the driven systems synchronized. Moreover, the estimate errors of the uncertain parameters converge to zero since the persistent excitation condition holds. Additionally, numerical simulations show the effectiveness of the proposed controllers.
Targeting engineering synchronization in chaotic systems
NASA Astrophysics Data System (ADS)
Bhowmick, Sourav K.; Ghosh, Dibakar
2016-07-01
A method of targeting engineering synchronization states in two identical and mismatch chaotic systems is explained in detail. The method is proposed using linear feedback controller coupling for engineering synchronization such as mixed synchronization, linear and nonlinear generalized synchronization and targeting fixed point. The general form of coupling design to target any desire synchronization state under unidirectional coupling with the help of Lyapunov function stability theory is derived analytically. A scaling factor is introduced in the coupling definition to smooth control without any loss of synchrony. Numerical results are done on two mismatch Lorenz systems and two identical Sprott oscillators.
Synchronously deployable truss structure
NASA Technical Reports Server (NTRS)
Bush, H. G. (Inventor); Mikulas, M., Jr. (Inventor); Wallsom, E. (Inventor)
1986-01-01
A collapsible-expandable truss structure, including first and second spaced surface truss layers having an attached core layer is described. The surface truss layers are composed of a plurality of linear struts arranged in multiple triangular configurations. Each linear strut is hinged at the center and hinge connected at each end to a nodular joint. A passive spring serves as the expansion force to move the folded struts from a stowed collapsed position to a deployed operative final truss configuration. A damper controls the rate of spring expansion for the synchronized deployment of the truss as the folded configuration is released for deployment by the restrain belts. The truss is synchronously extended under the control of motor driven spools.
Synchronous Photodiode-Signal Sampler
NASA Technical Reports Server (NTRS)
Primus, Howard K.
1988-01-01
Synchronous sampling circuit increases signal-to-noise ratio of measurements of chopped signal of known phase and frequency in presence of low-frequency or dc background noise. Used with linear array of photoelectric sensors for locating edge of metal plate. Multiplexing circuit cycles through 16 light-emitting-diode/photodiode pairs, under computer control. Synchronized with multiplexer so edge detector makes one background-subtracted signal measurement per emitter/detector pair in turn.
NASA Astrophysics Data System (ADS)
Steur, Erik; Murguia, Carlos; Fey, Rob H. B.; Nijmeijer, Henk
2016-06-01
We study experimentally synchronization and partial synchronization in networks of Hindmarsh-Rose model neurons that interact through linear time-delay couplings. Our experimental setup consists of electric circuit board realizations of the Hindmarsh-Rose model neuron and a coupling interface in which the interaction between the circuits is defined. With this experimental setup we test the predictive value of theoretical results about synchronization and partial synchronization in networks.
NASA Technical Reports Server (NTRS)
Sutton, John F. (Inventor)
1991-01-01
A synchronous demodulator includes a switch which is operated in synchronism with an incoming periodic signal and both divides and applies that signal to two signal channels. The two channels each include a network for computing and holding, for a predetermined length of time, the average signal value on that channel and applies those valves, in the form of two other signals, to the inputs of a differential amplifier. The networks may be R-C networks. The output of the differential amplifier may or may not form the output of the synchronous detector and may or may not be filtered. The output will not include a periodic signal due to the presence of a dc offset. Additionally, the output will not contain any substantial ripple due to periodic components in the input signal. In a somewhat more complex version, containing twice the structural components of the above synchronous demodulator with a more complex switching mechanism, essentially all ripple due to periodic components in the input signal are eliminated.
ERIC Educational Resources Information Center
Zhou, Ying; Gall, Walter; Nabb, Karen Mayumi
2006-01-01
"Imagine a tenth of a mile of river front with an unbroken line of trees with fireflies on ever leaf flashing in synchronism. ... Then, if one's imagination is sufficiently vivid, he may form some conception of this amazing spectacle." So wrote the naturalist Hugh Smith. In this article we consider how one might model mathematically the…
Safin, Damir A; Babashkina, Maria G; Robeyns, Koen; Mitoraj, Mariusz P; Kubisiak, Piotr; Garcia, Yann
2015-11-01
The reaction of the N-thiophosphorylated thiourea (HOCH2 )(Me)2 CNHC(S)NHP(S)(OiPr)2 (HL), deprotonated by the thiophosphorylamide group, with NiCl2 leads to green needles of the pseudotetrahedral complex [Ni(L-1,5-S,S')2 ]⋅0.5 (n-C6 H14 ) or pale green blocks of the trans square-planar complex trans-[Ni(L-1,5-S,S')2 ]. The former complex is stabilized by homopolar dihydrogen C-H⋅⋅⋅H-C interactions formed by n-hexane solvent molecules with the [Ni(L-1,5-S,S')2 ] unit. Furthermore, the dispersion-dominated C-H⋅⋅⋅ H-C interactions are, together with other noncovalent interactions (C-H⋅⋅⋅N, C-H⋅⋅⋅Ni, C-H⋅⋅⋅S), responsible for pseudotetrahedral coordination around the Ni(II) center in [Ni(L-1,5-S,S')2 ]⋅0.5 (n-C6 H14 ). PMID:26423780
Synchronous Control Method and Realization of Automated Pharmacy Elevator
NASA Astrophysics Data System (ADS)
Liu, Xiang-Quan
Firstly, the control method of elevator's synchronous motion is provided, the synchronous control structure of double servo motor based on PMAC is accomplished. Secondly, synchronous control program of elevator is implemented by using PMAC linear interpolation motion model and position error compensation method. Finally, the PID parameters of servo motor were adjusted. The experiment proves the control method has high stability and reliability.
Synchronizing noisy nonidentical oscillators by transient uncoupling
NASA Astrophysics Data System (ADS)
Tandon, Aditya; Schröder, Malte; Mannattil, Manu; Timme, Marc; Chakraborty, Sagar
2016-09-01
Synchronization is the process of achieving identical dynamics among coupled identical units. If the units are different from each other, their dynamics cannot become identical; yet, after transients, there may emerge a functional relationship between them—a phenomenon termed "generalized synchronization." Here, we show that the concept of transient uncoupling, recently introduced for synchronizing identical units, also supports generalized synchronization among nonidentical chaotic units. Generalized synchronization can be achieved by transient uncoupling even when it is impossible by regular coupling. We furthermore demonstrate that transient uncoupling stabilizes synchronization in the presence of common noise. Transient uncoupling works best if the units stay uncoupled whenever the driven orbit visits regions that are locally diverging in its phase space. Thus, to select a favorable uncoupling region, we propose an intuitive method that measures the local divergence at the phase points of the driven unit's trajectory by linearizing the flow and subsequently suppresses the divergence by uncoupling.
Noncoherent DTTLs for Symbol Synchronization
NASA Technical Reports Server (NTRS)
Simon, Marvin; Tkacenko, Andre
2007-01-01
Noncoherent data-transition tracking loops (DTTLs) have been proposed for use as symbol synchronizers in digital communication receivers. [Communication- receiver subsystems that can perform their assigned functions in the absence of synchronization with the phases of their carrier signals ( carrier synchronization ) are denoted by the term noncoherent, while receiver subsystems that cannot function without carrier synchronization are said to be coherent. ] The proposal applies, more specifically, to receivers of binary phase-shift-keying (BPSK) signals generated by directly phase-modulating binary non-return-to-zero (NRZ) data streams onto carrier signals having known frequencies but unknown phases. The proposed noncoherent DTTLs would be modified versions of traditional DTTLs, which are coherent. The symbol-synchronization problem is essentially the problem of recovering symbol timing from a received signal. In the traditional, coherent approach to symbol synchronization, it is necessary to establish carrier synchronization in order to recover symbol timing. A traditional DTTL effects an iterative process in which it first generates an estimate of the carrier phase in the absence of symbol-synchronization information, then uses the carrier-phase estimate to obtain an estimate of the symbol-synchronization information, then feeds the symbol-synchronization estimate back to the carrier-phase-estimation subprocess. In a noncoherent symbol-synchronization process, there is no need for carrier synchronization and, hence, no need for iteration between carrier-synchronization and symbol- synchronization subprocesses. The proposed noncoherent symbolsynchronization process is justified theoretically by a mathematical derivation that starts from a maximum a posteriori (MAP) method of estimation of symbol timing utilized in traditional, coherent DTTLs. In that MAP method, one chooses the value of a variable of interest (in this case, the offset in the estimated symbol
Physiological Synchronization in a Vigilance Dual Task.
Guastello, Stephen J
2016-01-01
The synchronization of autonomic arousal levels and other physio-logical responses between people is a potentially important component of work team performance, client-therapist relationships, and other types of human interaction. This study addressed several problems: What statistical models are viable for identifying synchronization for loosely coupled human systems? How is the level of synchronization related to psychosocial variables such as empathy, subjective ratings of workload, and actual performance? Participants were 70 undergraduates who worked in pairs on a vigilance dual task in which they watched a virtual reality security camera, rang a bell when they saw the target intruder, and completed a jig-saw puzzle. Event rates either increased or decreased during the 90 min work period. The average R2 values for each person were .66, .66, .62, and .53 for the linear autoregressive model, linear autoregressive model with a synchronization component, the nonlinear autoregressive model, and the nonlinear autoregressive model with a synchronization component, respectively. All models were more accurate at a lag of 20 sec compared to 50 sec or customized lag lengths. Although the linear models were more accurate overall, the nonlinear synchronization parameters were more often related to psychological variables and performance. In particular, greater synchronization was observed with the nonlinear model when the target event rate increased, compared to when it decreased, which was expected from the general theory of synchronization. Nonlinear models were also more effective for uncovering inhibitory or dampening relationships between the co-workers as well as mutually excitatory relationships. Future research should explore the comparative model results for tasks that induce higher levels of synchronization and involve different types of internal group coordination. PMID:26639921
Are feedback loops destructive to synchronization?
NASA Astrophysics Data System (ADS)
Sheshbolouki, A.; Zarei, M.; Sarbazi-Azad, H.
2015-08-01
We study the effects of directionality on synchronization of dynamical networks. Performing the linear stability analysis and the numerical simulation of the Kuramoto model in directed networks, we show that balancing in- and out-degrees of all nodes enhances the synchronization of sparse networks, especially in networks with high clustering coefficient and homogeneous degree distribution. Furthermore, by omitting all the feedback loops, we show that while hierarchical directed acyclic graphs are structurally highly synchronizable, their global synchronization is too sensitive to the choice of natural frequencies and is strongly affected by noise.
Automated ILA design for synchronous sequential circuits
NASA Technical Reports Server (NTRS)
Liu, M. N.; Liu, K. Z.; Maki, G. K.; Whitaker, S. R.
1991-01-01
An iterative logic array (ILA) architecture for synchronous sequential circuits is presented. This technique utilizes linear algebra to produce the design equations. The ILA realization of synchronous sequential logic can be fully automated with a computer program. A programmable design procedure is proposed to fullfill the design task and layout generation. A software algorithm in the C language has been developed and tested to generate 1 micron CMOS layouts using the Hewlett-Packard FUNGEN module generator shell.
Synchronizing redundant power oscillators
NASA Technical Reports Server (NTRS)
Jenson, K. J.
1969-01-01
Outputs of oscillators are synchronized by summing the power transformer phase voltages, the summed voltages are applied to the frequency determining inductors of the individual voltage-controlled power oscillators. The beat frequency is eliminated when synchronization is achieved.
Malm, C.F.
1995-12-31
A phase lock loop automatic synchronizer, PLLS, matches generator speed starting from dead stop to bus frequency, and then locks the phase difference at zero, thereby maintaining zero slip frequency while the generator breaker is being closed to the bus. The significant difference between the PLLS and a conventional automatic synchronizer is that there is no slip frequency difference between generator and bus. The PLL synchronizer is most advantageous when the penstock pressure fluctuates the grid frequency fluctuates, or both. The PLL synchronizer is relatively inexpensive. Hydroplants with multiple units can economically be equipped with a synchronizer for each unit.
Collapse of Synchronization in a Memristive Network
NASA Astrophysics Data System (ADS)
Lü, Mi; Wang, Chun-Ni; Tang, Jun; Ma, Jun
2015-12-01
For an oscillating circuit or coupled circuits, damage in electric devices such as inductor, resistance, memristor even capacitor can cause breakdown or collapse of the circuits. These damage could be associated with external attack or aging in electric devices, and then the bifurcation parameters could be deformed from normal values. Resonators or signal generators are often synchronized to produce powerful signal series and this problem could be investigated by using synchronization in network. Complete synchronization could be induced by linear coupling in a two-dimensional network of identical oscillators when the coupling intensity is beyond certain threshold. The collective behavior and synchronization state are much dependent on the bifurcation parameters. Any slight fluctuation in parameter and breakdown in bifurcation parameter can cause transition of synchronization even collapse of synchronization in the network. In this paper, a two-dimensional network composed of the resonators coupled with memristors under nearest-neighbor connection is designed, and the network can reach complete synchronization by carefully selecting coupling intensity. The network keeps synchronization after certain transient period, then a bifurcation parameter in a resonator is switched from the previous value and the adjacent resonators (oscillators) are affected in random. It is found that the synchronization area could be invaded greatly in a diffusive way. The damage area size is much dependent on the selection of diffusive period of damage and deformation degree in the parameter. Indeed, the synchronization area could keep intact at largest size under intermediate deformation degree and coupling intensity. Supported by the National Natural Science of China under Grant Nos. 11265008 and 11365014
Synchronization of chaotic systems
Pecora, Louis M.; Carroll, Thomas L.
2015-09-15
We review some of the history and early work in the area of synchronization in chaotic systems. We start with our own discovery of the phenomenon, but go on to establish the historical timeline of this topic back to the earliest known paper. The topic of synchronization of chaotic systems has always been intriguing, since chaotic systems are known to resist synchronization because of their positive Lyapunov exponents. The convergence of the two systems to identical trajectories is a surprise. We show how people originally thought about this process and how the concept of synchronization changed over the years to a more geometric view using synchronization manifolds. We also show that building synchronizing systems leads naturally to engineering more complex systems whose constituents are chaotic, but which can be tuned to output various chaotic signals. We finally end up at a topic that is still in very active exploration today and that is synchronization of dynamical systems in networks of oscillators.
Synchronization of chaotic systems
NASA Astrophysics Data System (ADS)
Pecora, Louis M.; Carroll, Thomas L.
2015-09-01
We review some of the history and early work in the area of synchronization in chaotic systems. We start with our own discovery of the phenomenon, but go on to establish the historical timeline of this topic back to the earliest known paper. The topic of synchronization of chaotic systems has always been intriguing, since chaotic systems are known to resist synchronization because of their positive Lyapunov exponents. The convergence of the two systems to identical trajectories is a surprise. We show how people originally thought about this process and how the concept of synchronization changed over the years to a more geometric view using synchronization manifolds. We also show that building synchronizing systems leads naturally to engineering more complex systems whose constituents are chaotic, but which can be tuned to output various chaotic signals. We finally end up at a topic that is still in very active exploration today and that is synchronization of dynamical systems in networks of oscillators.
Remote bistatic receiver synchronization using DLL techniques
NASA Astrophysics Data System (ADS)
Aguasca, A.; Broquetas, A.; Fdez de Muniain, J.; Ambros, A.
An experimental staggered pulse repetition frequency synchronizer, based on a delay-lock loop (DLL) was tested using a transmitter signal simulator that simulates the staggering sequence windowed by the antenna beam. The measured system performance ensures synchronization with a 30-ms direct illumination, with an accumulated delay error in the order of the resolution cell positioning error in range. An artificial time expansion of the received pulses is performed in order to reduce the acquisition time synchronization. A bistatic radar synchronization method based on DLL was is analyzed by linearization of the different parts and signals involved. The parameters that degrade system performance are obtained. And some solutions are represented in order to minimize their effects.
Synchronizing large systolic arrays
Fisher, A.L.; Kung, H.T.
1982-04-01
Parallel computing structures consist of many processors operating simultaneously. If a concurrent structure is regular, as in the case of systolic array, it may be convenient to think of all processors as operating in lock step. Totally synchronized systems controlled by central clocks are difficult to implement because of the inevitable problem of clock skews and delays. An alternate means of enforcing necessary synchronization is the use of self-timed, asynchronous schemes, at the cost of increased design complexity and hardware cost. Realizing that different circumstances call for different synchronization methods, this paper provides a spectrum of synchronization models; based on the assumptions made for each model, theoretical lower bounds on clock skew are derived, and appropriate or best-possible synchronization schemes for systolic arrays are proposed. This paper represents a first step towards a systematic study of synchronization problems for large systolic arrays.
Synchronization of Neural Networks of Neutral Type with Stochastic Perturbation
NASA Astrophysics Data System (ADS)
Park, Ju H.; Kwon, O. M.
In this letter, the problem of feedback controller design to achieve synchronization for neural network of neutral type with stochastic perturbation is considered. Based on Lyapunov method and LMI (linear matrix inequality) framework, the goal of this letter is to derive an existence criterion of the controller for the synchronization between master and response networks.
Bifurcation behaviors of synchronized regions in logistic map networks with coupling delay
Tang, Longkun E-mail: xqwu@whu.edu.cn; Wu, Xiaoqun E-mail: xqwu@whu.edu.cn; Lu, Jun-an; Lü, Jinhu
2015-03-15
Network synchronized regions play an extremely important role in network synchronization according to the master stability function framework. This paper focuses on network synchronous state stability via studying the effects of nodal dynamics, coupling delay, and coupling way on synchronized regions in Logistic map networks. Theoretical and numerical investigations show that (1) network synchronization is closely associated with its nodal dynamics. Particularly, the synchronized region bifurcation points through which the synchronized region switches from one type to another are in good agreement with those of the uncoupled node system, and chaotic nodal dynamics can greatly impede network synchronization. (2) The coupling delay generally impairs the synchronizability of Logistic map networks, which is also dominated by the parity of delay for some nodal parameters. (3) A simple nonlinear coupling facilitates network synchronization more than the linear one does. The results found in this paper will help to intensify our understanding for the synchronous state stability in discrete-time networks with coupling delay.
Synchronization via Hydrodynamic Interactions
NASA Astrophysics Data System (ADS)
Kendelbacher, Franziska; Stark, Holger
2013-12-01
An object moving in a viscous fluid creates a flow field that influences the motion of neighboring objects. We review examples from nature in the microscopic world where such hydrodynamic interactions synchronize beating or rotating filaments. Bacteria propel themselves using a bundle of rotating helical filaments called flagella which have to be synchronized in phase. Other micro-organisms are covered with a carpet of smaller filaments called cilia on their surfaces. They beat highly synchronized so that metachronal waves propagate along the cell surfaces. We explore both examples with the help of simple model systems and identify generic properties for observing synchronization by hydrodynamic interactions.
Synchronization of genetic oscillators
NASA Astrophysics Data System (ADS)
Zhou, Tianshou; Zhang, Jiajun; Yuan, Zhanjiang; Chen, Luonan
2008-09-01
Synchronization of genetic or cellular oscillators is a central topic in understanding the rhythmicity of living organisms at both molecular and cellular levels. Here, we show how a collective rhythm across a population of genetic oscillators through synchronization-induced intercellular communication is achieved, and how an ensemble of independent genetic oscillators is synchronized by a common noisy signaling molecule. Our main purpose is to elucidate various synchronization mechanisms from the viewpoint of dynamics, by investigating the effects of various biologically plausible couplings, several kinds of noise, and external stimuli. To have a comprehensive understanding on the synchronization of genetic oscillators, we consider three classes of genetic oscillators: smooth oscillators (exhibiting sine-like oscillations), relaxation oscillators (displaying jump dynamics), and stochastic oscillators (noise-induced oscillation). For every class, we further study two cases: with intercellular communication (including phase-attractive and repulsive coupling) and without communication between cells. We find that an ensemble of smooth oscillators has different synchronization phenomena from those in the case of relaxation oscillators, where noise plays a different but key role in synchronization. To show differences in synchronization between them, we make comparisons in many aspects. We also show that a population of genetic stochastic oscillators have their own synchronization mechanisms. In addition, we present interesting phenomena, e.g., for relaxation-type stochastic oscillators coupled to a quorum-sensing mechanism, different noise intensities can induce different periodic motions (i.e., inhomogeneous limit cycles).
Transient Uncoupling Induces Synchronization.
Schröder, Malte; Mannattil, Manu; Dutta, Debabrata; Chakraborty, Sagar; Timme, Marc
2015-07-31
Finding conditions that support synchronization is a fertile and active area of research with applications across multiple disciplines. Here we present and analyze a scheme for synchronizing chaotic dynamical systems by transiently uncoupling them. Specifically, systems coupled only in a fraction of their state space may synchronize even if fully coupled they do not. While for many standard systems coupling strengths need to be bounded to ensure synchrony, transient uncoupling removes this bound and thus enables synchronization in an infinite range of effective coupling strengths. The presented coupling scheme therefore opens up the possibility to induce synchrony in (biological or technical) systems whose parameters are fixed and cannot be modified continuously. PMID:26274420
Transient Uncoupling Induces Synchronization
NASA Astrophysics Data System (ADS)
Schröder, Malte; Mannattil, Manu; Dutta, Debabrata; Chakraborty, Sagar; Timme, Marc
2015-07-01
Finding conditions that support synchronization is a fertile and active area of research with applications across multiple disciplines. Here we present and analyze a scheme for synchronizing chaotic dynamical systems by transiently uncoupling them. Specifically, systems coupled only in a fraction of their state space may synchronize even if fully coupled they do not. While for many standard systems coupling strengths need to be bounded to ensure synchrony, transient uncoupling removes this bound and thus enables synchronization in an infinite range of effective coupling strengths. The presented coupling scheme therefore opens up the possibility to induce synchrony in (biological or technical) systems whose parameters are fixed and cannot be modified continuously.
NASA Technical Reports Server (NTRS)
1980-01-01
The synchronous technology requirements for large space power systems are summarized. A variety of technology areas including photovoltaics, thermal management, and energy storage, and power management are addressed.
Chaos synchronization and parameter estimation from a scalar output signal.
Chen, Maoyin; Kurths, Jürgen
2007-08-01
We propose an observer-based approach for chaos synchronization and parameter estimation from a scalar output signal. To begin with, we use geometric control to transform the master system into a standard form with zero dynamics. Then we construct a slaver to synchronize with the master using a combination of slide mode control and linear feedback control. Within a finite time, partial synchronization is realized, which further results in complete synchronization as time tends to infinity. Even if there exists model uncertainty in the slaver, we can also estimate the unknown model parameter by a simple adaptive rule. PMID:17930180
EEG synchronization and migraine
NASA Astrophysics Data System (ADS)
Stramaglia, Sebastiano; Angelini, Leonardo; Pellicoro, Mario; Hu, Kun; Ivanov, Plamen Ch.
2004-03-01
We investigate phase synchronization in EEG recordings from migraine patients. We use the analytic signal technique, based on the Hilbert transform, and find that migraine brains are characterized by enhanced alpha band phase synchronization in presence of visual stimuli. Our findings show that migraine patients have an overactive regulatory mechanism that renders them more sensitive to external stimuli.
SONET synchronization: What's happening
NASA Technical Reports Server (NTRS)
Cubbage, Robert W.
1993-01-01
Almost everyone that has heard of SONET knows that the acronym stands for Synchronous Optical NETwork. There has been a host of magazine articles on SONET rings, SONET features, even SONET compatibility with digital radio. What has not been highly publicized is the critical relationship between SONET, network synchronization, and payload jitter. This topic is addressed.
SONET synchronization: What's happening
NASA Astrophysics Data System (ADS)
Cubbage, Robert W.
1993-06-01
Almost everyone that has heard of SONET knows that the acronym stands for Synchronous Optical NETwork. There has been a host of magazine articles on SONET rings, SONET features, even SONET compatibility with digital radio. What has not been highly publicized is the critical relationship between SONET, network synchronization, and payload jitter. This topic is addressed.
GENERAL: Bistability in Coupled Oscillators Exhibiting Synchronized Dynamics
NASA Astrophysics Data System (ADS)
Olusola, O. I.; Vincent, U. E.; Njah, A. N.; Olowofela, J. A.
2010-05-01
We report some new results associated with the synchronization behavior of two coupled double-well Duffing oscillators (DDOs). Some sufficient algebraic criteria for global chaos synchronization of the drive and response DDOs via linear state error feedback control are obtained by means of Lyapunov stability theory. The synchronization is achieved through a bistable state in which a periodic attractor co-exists with a chaotic attractor. Using the linear perturbation analysis, the prevalence of attractors in parameter space and the associated bifurcations are examined. Subcritical and supercritical Hopf bifurcations and abundance of Arnold tongues — a signature of mode locking phenomenon are found.
Synchronous Discrete Harmonic Oscillator
Antippa, Adel F.; Dubois, Daniel M.
2008-10-17
We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2{pi} in phase space, is an integral multiple N of the discrete time step {delta}t. It is fully synchronous when N is even. It is pseudo-synchronous when T/{delta}t is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is ''blue shifted'' relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval {delta}t. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.
Advanced synchronous luminescence system
Vo-Dinh, Tuan
1997-01-01
A method and apparatus for determining the condition of tissue or otherwise making chemical identifications includes exposing the sample to a light source, and using a synchronous luminescence system to produce a spectrum that can be analyzed for tissue condition.
Synchronization in complex networks
Arenas, A.; Diaz-Guilera, A.; Moreno, Y.; Zhou, C.; Kurths, J.
2007-12-12
Synchronization processes in populations of locally interacting elements are in the focus of intense research in physical, biological, chemical, technological and social systems. The many efforts devoted to understand synchronization phenomena in natural systems take now advantage of the recent theory of complex networks. In this review, we report the advances in the comprehension of synchronization phenomena when oscillating elements are constrained to interact in a complex network topology. We also overview the new emergent features coming out from the interplay between the structure and the function of the underlying pattern of connections. Extensive numerical work as well as analytical approaches to the problem are presented. Finally, we review several applications of synchronization in complex networks to different disciplines: biological systems and neuroscience, engineering and computer science, and economy and social sciences.
NASA Technical Reports Server (NTRS)
Rogers, J. R., III
1980-01-01
Flexible simulator for trouble-shooting data transmission system uses binary synchronous communications protocol to produce error-free transmission of data between two points. Protocol may be used to replace display generator or be directly fed to display generator.
Synchronization in complex networks
NASA Astrophysics Data System (ADS)
Arenas, Alex; Díaz-Guilera, Albert; Kurths, Jurgen; Moreno, Yamir; Zhou, Changsong
2008-12-01
Synchronization processes in populations of locally interacting elements are the focus of intense research in physical, biological, chemical, technological and social systems. The many efforts devoted to understanding synchronization phenomena in natural systems now take advantage of the recent theory of complex networks. In this review, we report the advances in the comprehension of synchronization phenomena when oscillating elements are constrained to interact in a complex network topology. We also take an overview of the new emergent features coming out from the interplay between the structure and the function of the underlying patterns of connections. Extensive numerical work as well as analytical approaches to the problem are presented. Finally, we review several applications of synchronization in complex networks to different disciplines: biological systems and neuroscience, engineering and computer science, and economy and social sciences.
Pinning synchronization of a mobile agent network
NASA Astrophysics Data System (ADS)
Wang, Lei; Sun, You-xian
2009-11-01
We investigate the problem of controlling a group of mobile agents in a plane in order to move them towards a desired orbit via pinning control, in which each agent is associated with a chaotic oscillator coupled with those of neighboring agents, and the pinning strategy is to have the common linear feedback acting on a small fraction of agents by random selection. We explore the effects of the pinning probability, feedback gains and agent density in the pinning synchronization of a mobile agent network under a fast-switching constraint, and perform numerical simulations for validation. In particular, we show that there exists a critical pinning density for network synchronization with an unbounded region: above the threshold, the dynamical network can be controlled by pinning; below it, anarchy prevails. And for the network with a single bounded synchronization region, pinning control has little effect as regards enhancing network synchronizability.
Hypothesis test for synchronization: Twin surrogates revisited
NASA Astrophysics Data System (ADS)
Romano, M. Carmen; Thiel, Marco; Kurths, Jürgen; Mergenthaler, Konstantin; Engbert, Ralf
2009-03-01
The method of twin surrogates has been introduced to test for phase synchronization of complex systems in the case of passive experiments. In this paper we derive new analytical expressions for the number of twins depending on the size of the neighborhood, as well as on the length of the trajectory. This allows us to determine the optimal parameters for the generation of twin surrogates. Furthermore, we determine the quality of the twin surrogates with respect to several linear and nonlinear statistics depending on the parameters of the method. In the second part of the paper we perform a hypothesis test for phase synchronization in the case of experimental data from fixational eye movements. These miniature eye movements have been shown to play a central role in neural information processing underlying the perception of static visual scenes. The high number of data sets (21 subjects and 30 trials per person) allows us to compare the generated twin surrogates with the "natural" surrogates that correspond to the different trials. We show that the generated twin surrogates reproduce very well all linear and nonlinear characteristics of the underlying experimental system. The synchronization analysis of fixational eye movements by means of twin surrogates reveals that the synchronization between the left and right eye is significant, indicating that either the centers in the brain stem generating fixational eye movements are closely linked, or, alternatively that there is only one center controlling both eyes.
A spatio-temporal filter approach to synchronous brain activities.
Nakagawa, T; Ohashi, A
1980-01-01
This paper presents a mathematical mechanism for neuronal synchronization in oscillatory brain activities on the basis of the layer structures with recurrent inhibition. To begin with, a linear theory reveals that the recurrent inhibition tends to cause a synchronous uniform oscillation if the loop delay increases, and that an oscillating neuron recruits neighboring neurons by delivering synchronous inputs through the recurrent inhibition loop if the frequency is that of the selfexcitatory oscillation. Then, a quasilinearized dual wave model (DWM), employing the two-sinusoids plus bias input describing functions (TSBDF), shows the competitive relationship between the synchronous oscillation and a spatial wave that is introduced to represent normal brain activity patterns. Results of computer simulations conform well to the predictions of the DWM. Thus, synchronous brain activities are suggested to be the result of the spatio-temporal filter characteristics of the brain layer structures, modified by the neural nonlinearity. PMID:7353063
Optimistic barrier synchronization
NASA Technical Reports Server (NTRS)
Nicol, David M.
1992-01-01
Barrier synchronization is fundamental operation in parallel computation. In many contexts, at the point a processor enters a barrier it knows that it has already processed all the work required of it prior to synchronization. The alternative case, when a processor cannot enter a barrier with the assurance that it has already performed all the necessary pre-synchronization computation, is treated. The problem arises when the number of pre-sychronization messages to be received by a processor is unkown, for example, in a parallel discrete simulation or any other computation that is largely driven by an unpredictable exchange of messages. We describe an optimistic O(log sup 2 P) barrier algorithm for such problems, study its performance on a large-scale parallel system, and consider extensions to general associative reductions as well as associative parallel prefix computations.
Synchronization in Superradiant Lasers
NASA Astrophysics Data System (ADS)
Cox, Kevin; Weiner, Joshua; Bohnet, Justin; Thompson, James
2015-05-01
Superradiant (or bad-cavity) lasers based on highly forbidden transitions in cold atoms are expected to produce light with coherence properties exceeding the state-of-the-art, finding applications in optical atomic clocks and other precision measurements. We study experimentally and theoretically the response of a superradiant Raman laser to an applied coherent drive. We observe two forms of synchronization (injection locking) between the superradiant ensemble and the applied drive: one attractive and one repulsive in nature, in which the atomic spin degrees of freedom play a crucial role in determining the dynamics. Additionally, we present time dynamics and steady state behavior of two interacting superradiant lasers. Understanding the synchronization physics of superradiant lasers could inform future implementations with technologically relevant phase noise properties and explorations for understanding synchronization in a quantum regime.
Synchronization of rigid microrotors by time-dependent hydrodynamic interactions.
Theers, Mario; Winkler, Roland G
2013-08-01
We investigate the emergent dynamical behavior of hydrodynamically coupled microrotors. The two rotors are confined in a plane and move along circles driven by active forces. The three-dimensional fluid is described by the linearized, time-dependent Navier-Stokes equations instead of the usually adopted Stokes equations. We demonstrate that time-dependent hydrodynamic interactions lead to synchronization of the rotational motion. The time dependence of the phase difference between the rotors is determined and synchronization times are extracted for various external torques and rotor separations by solving the underlaying integrodifferential equations numerically. In addition, an analytical expression is provided for the synchronization time. PMID:24032929
An active control synchronization for two modified Chua circuits
NASA Astrophysics Data System (ADS)
Li, Guo-Hui
2005-03-01
From modern control theory, an active control method to synchronize two modified Chua circuits with each other, which exhibit chaos, is presented. Some sufficient conditions of linear stability of the chaotic synchronization are obtained from rigorous mathematic justification. On the basis of the state-observer, the controller is analytically deduced using the active control. It is shown that this technique can be applied to achieve synchronization of the two systems with each other, whether they are identical or not. Finally, numerical simulations show the effectiveness of the proposed control scheme.
Cluster synchronization in networks of neurons with chemical synapses
Juang, Jonq; Liang, Yu-Hao
2014-03-15
In this work, we study the cluster synchronization of chemically coupled and generally formulated networks which are allowed to be nonidentical. The sufficient condition for the existence of stably synchronous clusters is derived. Specifically, we only need to check the stability of the origins of m decoupled linear systems. Here, m is the number of subpopulations. Examples of nonidentical networks such as Hindmarsh-Rose (HR) neurons with various choices of parameters in different subpopulations, or HR neurons in one subpopulation and FitzHugh-Nagumo neurons in the other subpopulation are provided. Explicit threshold for the coupling strength that guarantees the stably cluster synchronization can be obtained.
Pinning synchronization of discrete dynamical networks with delay coupling
NASA Astrophysics Data System (ADS)
Cheng, Ranran; Peng, Mingshu; Zuo, Jun
2016-05-01
The purpose of this paper is to investigate the pinning synchronization analysis for nonlinear coupled delayed discrete dynamical networks with the identical or nonidentical topological structure. Based on the Lyapunov stability theory, pinning control method and linear matrix inequalities, several adaptive synchronization criteria via two kinds of pinning control method are obtained. Two examples based on Rulkov chaotic system are included to illustrate the effectiveness and verification of theoretical analysis.
Adaptive pinning synchronization in fractional-order uncertain complex dynamical networks with delay
NASA Astrophysics Data System (ADS)
Liang, Song; Wu, Ranchao; Chen, Liping
2016-02-01
Based on the stability theory of fractional-order systems, synchronization of general fractional-order uncertain complex networks with delay is investigated in this paper. By the inequality of the fractional derivative and the comparison principle of the linear fractional equation with delay, synchronization of complex networks with delay is realized under adaptive control. Some sufficient criteria ensuring local asymptotical synchronization under adaptive control and global asymptotical synchronization under adaptive pinning control are derived, respectively. Finally, numerical simulations are presented to demonstrate the validity and feasibility of the proposed synchronization criteria.
Advanced synchronous luminescence system
Vo-Dinh, T.
1997-02-04
A method and apparatus are disclosed for determining the condition of tissue or otherwise making chemical identifications includes exposing the sample to a light source, and using a synchronous luminescence system to produce a spectrum that can be analyzed for tissue condition. 14 figs.
Implementing the Synchronous Classroom
ERIC Educational Resources Information Center
Furman, Jan A.
2010-01-01
This commentary describes an action research project conducted by selected staff at the Northern Valley Regional High School District in New Jersey. The project focused on the idea of developing a synchronous classroom to provide world language learning opportunities to students. Relevant research is provided as are ideas regarding logistics and…
Synchronized time stamp support
Kowalkowski, J.
1994-02-16
New software has been added to IOC core to maintain time stamps. The new software has the ability to maintain time stamps over all IOCs on a network. The purpose of this paper is to explain how EPICS will synchronize the time stamps. In addition, this paper will explain how to configure and use the new EPICS time stamp support software.
Control of Abnormal Synchronization in Neurological Disorders
Popovych, Oleksandr V.; Tass, Peter A.
2014-01-01
In the nervous system, synchronization processes play an important role, e.g., in the context of information processing and motor control. However, pathological, excessive synchronization may strongly impair brain function and is a hallmark of several neurological disorders. This focused review addresses the question of how an abnormal neuronal synchronization can specifically be counteracted by invasive and non-invasive brain stimulation as, for instance, by deep brain stimulation for the treatment of Parkinson’s disease, or by acoustic stimulation for the treatment of tinnitus. On the example of coordinated reset (CR) neuromodulation, we illustrate how insights into the dynamics of complex systems contribute to successful model-based approaches, which use methods from synergetics, non-linear dynamics, and statistical physics, for the development of novel therapies for normalization of brain function and synaptic connectivity. Based on the intrinsic multistability of the neuronal populations induced by spike timing-dependent plasticity (STDP), CR neuromodulation utilizes the mutual interdependence between synaptic connectivity and dynamics of the neuronal networks in order to restore more physiological patterns of connectivity via desynchronization of neuronal activity. The very goal is to shift the neuronal population by stimulation from an abnormally coupled and synchronized state to a desynchronized regime with normalized synaptic connectivity, which significantly outlasts the stimulation cessation, so that long-lasting therapeutic effects can be achieved. PMID:25566174
Synchronization and hydrodynamic interactions
NASA Astrophysics Data System (ADS)
Powers, Thomas; Qian, Bian; Breuer, Kenneth
2008-03-01
Cilia and flagella commonly beat in a coordinated manner. Examples include the flagella that Volvox colonies use to move, the cilia that sweep foreign particles up out of the human airway, and the nodal cilia that set up the flow that determines the left-right axis in developing vertebrate embryos. In this talk we present an experimental study of how hydrodynamic interactions can lead to coordination in a simple idealized system: two nearby paddles driven with fixed torques in a highly viscous fluid. The paddles attain a synchronized state in which they rotate together with a phase difference of 90 degrees. We discuss how synchronization depends on system parameters and present numerical calculations using the method of regularized stokeslets.
Synchronization of Eukaryotic Flagella
NASA Astrophysics Data System (ADS)
Goldstein, Raymond E.
2012-11-01
From unicellular organisms as small as a few microns to the largest vertebrates on earth we find groups of beating flagella or cilia that exhibit striking spatio-temporal organization. This may take the form of precise frequency and phase locking as frequently found in the swimming of green algae, or beating with long-wavelength phase modulations known as metachronal waves, seen in ciliates and in our respiratory systems. The remarkable similarity in the underlying molecular structure of flagella across the whole eukaryotic world leads naturally to the hypothesis that a similarly universal mechanism might be responsible for synchronization. Although this mechanism is poorly understood, one appealing hypothesis is that it results from hydrodynamic interactions between flagella. In this talk I will describe a synthesis of recent experimental and theoretical studies of this issue that have provided the strongest evidence to date for the hydrodynamic origin of flagellar synchronization. At the unicellular level this includes studies of the beating of the two flagella of the wild type unicellular alga Chlamydomonas reinhardtii in their native state and under conditions of regrowth following autotomy, and of the flagellar dominance mutant ptx1, which displays unusual anti-phase synchronization. Analysis of the related multicellular organism Volvox carteri shows it to be an ideal model organism for the study of metachronal waves. Supported by BBSRC, EPSRC, ERC, and The Wellcome Trust.
Superinsulator and quantum synchronization.
Vinokur, V. M.; Baturina, T. I.; Fistul, M. V.; Mironov, A. Yu.; Baklanov, M. R.; Strunk, C.; Materials Science Division; Inst. Semiconductor Physics; Univ. Regensburg; Ruhr-Univ. Bochum; IMEC
2008-04-01
Synchronized oscillators are ubiquitous in nature, and synchronization plays a key part in various classical and quantum phenomena. Several experiments have shown that in thin superconducting films, disorder enforces the droplet-like electronic texture 'superconducting islands immersed into a normal matrix' and that tuning disorder drives the system from superconducting to insulating behavior. In the vicinity of the transition, a distinct state forms: a Cooper-pair insulator, with thermally activated conductivity. It results from synchronization of the phase of the superconducting order parameter at the islands across the whole system. Here we show that at a certain finite temperature, a Cooper-pair insulator undergoes a transition to a superinsulating state with infinite resistance. We present experimental evidence of this transition in titanium nitride films and show that the superinsulating state is dual to the superconducting state: it is destroyed by a sufficiently strong critical magnetic field, and breaks down at some critical voltage that is analogous to the critical current in superconductors.
Emergency Response Synchronization Matrix
Energy Science and Technology Software Center (ESTSC)
1999-06-01
An emergency response to a disaster is complex, requiring the rapid integration, coordination, and synchronization of multiple levels of governmental and non-governmental organizations from numerous jurisdictions into a unified community response. For example, a communitys response actions to a fixed site hazardous materials incident could occur in an area extending from an on-site storage location to points 25 or more miles away. Response actions are directed and controlled by local governments and agencies situated withinmore » the response area, as well as by state and federal operaticns centers quite removed from the area of impact. Time is critical and the protective action decision-making process is greatly compressed. The response community must carefully plan and coordinate response operations in order to have confidence that they will be effectively implemented when faced with the potentially catastrophic nature of such releases. A graphical depiction of the entire response process via an emergency response synchronization matrix is an effective tool in optimizing the planning, exercising, and implementation of emergency plans. This systembased approach to emergency planning depicts how a community organizes its response tasks across space and time in relation to hazard actions. It provides the opportunity to make realtime adjustments as necessary for maximizing the often limited resources in protecting area residents. A response must involve the entire community and must not be limited by individual jurisdictions and organizations acting on their own without coordination, integration, and synchronization.« less
Digital Synchronizer without Metastability
NASA Technical Reports Server (NTRS)
Simle, Robert M.; Cavazos, Jose A.
2009-01-01
A proposed design for a digital synchronizing circuit would eliminate metastability that plagues flip-flop circuits in digital input/output interfaces. This metastability is associated with sampling, by use of flip-flops, of an external signal that is asynchronous with a clock signal that drives the flip-flops: it is a temporary flip-flop failure that can occur when a rising or falling edge of an asynchronous signal occurs during the setup and/or hold time of a flip-flop. The proposed design calls for (1) use of a clock frequency greater than the frequency of the asynchronous signal, (2) use of flip-flop asynchronous preset or clear signals for the asynchronous input, (3) use of a clock asynchronous recovery delay with pulse width discriminator, and (4) tying the data inputs to constant logic levels to obtain (5) two half-rate synchronous partial signals - one for the falling and one for the rising edge. Inasmuch as the flip-flop data inputs would be permanently tied to constant logic levels, setup and hold times would not be violated. The half-rate partial signals would be recombined to construct a signal that would replicate the original asynchronous signal at its original rate but would be synchronous with the clock signal.
Socially synchronized circadian oscillators
Bloch, Guy; Herzog, Erik D.; Levine, Joel D.; Schwartz, William J.
2013-01-01
Daily rhythms of physiology and behaviour are governed by an endogenous timekeeping mechanism (a circadian ‘clock’). The alternation of environmental light and darkness synchronizes (entrains) these rhythms to the natural day–night cycle, and underlying mechanisms have been investigated using singly housed animals in the laboratory. But, most species ordinarily would not live out their lives in such seclusion; in their natural habitats, they interact with other individuals, and some live in colonies with highly developed social structures requiring temporal synchronization. Social cues may thus be critical to the adaptive function of the circadian system, but elucidating their role and the responsible mechanisms has proven elusive. Here, we highlight three model systems that are now being applied to understanding the biology of socially synchronized circadian oscillators: the fruitfly, with its powerful array of molecular genetic tools; the honeybee, with its complex natural society and clear division of labour; and, at a different level of biological organization, the rodent suprachiasmatic nucleus, site of the brain's circadian clock, with its network of mutually coupled single-cell oscillators. Analyses at the ‘group’ level of circadian organization will likely generate a more complex, but ultimately more comprehensive, view of clocks and rhythms and their contribution to fitness in nature. PMID:23825203
A novel approach to synchronization of nonlinearly coupled network systems with delays
NASA Astrophysics Data System (ADS)
Tseng, Jui-Pin
2016-06-01
In this investigation, a novel approach to establishing the global synchronization of coupled network systems is presented. Under this approach, individual subsystems can be non-autonomous, and the coupling configuration is rather general. The coupling terms can be non-diffusive, nonlinear, time-dependent, asymmetric, and with time delays. With an iteration scheme, the problem of synchronization is transformed into solving a corresponding linear system of algebraic equations. Subsequently, delay-dependent and delay-independent criteria for global synchronization can be established. We implement the present approach to analyze synchronization of the FitzHugh-Nagumo systems under delayed and nonlinear sigmoidal coupling. Two examples are presented to demonstrate new dynamical scenarios, where oscillatory behavior and multistability emerge or are suppressed as the coupled neurons synchronize under the synchronization criterion. In addition, asynchrony induced by the coupling strength or coupling delay occurs while the synchronization criterion is violated.
Practical synchronization on complex dynamical networks via optimal pinning control.
Li, Kezan; Sun, Weigang; Small, Michael; Fu, Xinchu
2015-07-01
We consider practical synchronization on complex dynamical networks under linear feedback control designed by optimal control theory. The control goal is to minimize global synchronization error and control strength over a given finite time interval, and synchronization error at terminal time. By utilizing the Pontryagin's minimum principle, and based on a general complex dynamical network, we obtain an optimal system to achieve the control goal. The result is verified by performing some numerical simulations on Star networks, Watts-Strogatz networks, and Barabási-Albert networks. Moreover, by combining optimal control and traditional pinning control, we propose an optimal pinning control strategy which depends on the network's topological structure. Obtained results show that optimal pinning control is very effective for synchronization control in real applications. PMID:26274112
Receptors as a master key for synchronization of rhythms
NASA Astrophysics Data System (ADS)
Nagano, Seido
2004-03-01
A simple, but general scheme to achieve synchronization of rhythms was derived. The scheme has been inductively generalized from the modelling study of cellular slime mold. It was clarified that biological receptors work as apparatuses that can convert external stimulus to the form of nonlinear interaction within individual oscillators. Namely, the mathematical model receptor works as a nonlinear coupling apparatus between nonlinear oscillators. Thus, synchronization is achieved as a result of competition between two kinds of non-linearities, and to achieve synchronization, even a small external stimulation via model receptors can change the characteristics of individual oscillators significantly. The derived scheme is very simple mathematically, but it is a very powerful scheme as numerically demonstrated. The biological receptor scheme should significantly help understanding of synchronization phenomena in biology since groups of limit cycle oscillators and receptors are ubiquitous in biological systems. Reference: S. Nagano, Phys Rev. E67, 056215(2003)
Breathing synchronization in interconnected networks
Louzada, V. H. P.; Araújo, N. A. M.; Andrade, J. S.; Herrmann, H. J.
2013-01-01
Global synchronization in a complex network of oscillators emerges from the interplay between its topology and the dynamics of the pairwise interactions among its numerous components. When oscillators are spatially separated, however, a time delay appears in the interaction which might obstruct synchronization. Here we study the synchronization properties of interconnected networks of oscillators with a time delay between networks and analyze the dynamics as a function of the couplings and communication lag. We discover a new breathing synchronization regime, where two groups appear in each network synchronized at different frequencies. Each group has a counterpart in the opposite network, one group is in phase and the other in anti-phase with their counterpart. For strong couplings, instead, networks are internally synchronized but a phase shift between them might occur. The implications of our findings on several socio-technical and biological systems are discussed. PMID:24256765
Speed of complex network synchronization
NASA Astrophysics Data System (ADS)
Grabow, C.; Grosskinsky, S.; Timme, M.
2011-12-01
Synchrony is one of the most common dynamical states emerging on networks. The speed of convergence towards synchrony provides a fundamental collective time scale for synchronizing systems. Here we study the asymptotic synchronization times for directed networks with topologies ranging from completely ordered, grid-like, to completely disordered, random, including intermediate, partially disordered topologies. We extend the approach of master stability functions to quantify synchronization times. We find that the synchronization times strongly and systematically depend on the network topology. In particular, at fixed in-degree, stronger topological randomness induces faster synchronization, whereas at fixed path length, synchronization is slowest for intermediate randomness in the small-world regime. Randomly rewiring real-world neural, social and transport networks confirms this picture.
Sun synchronous solar refrigeration
NASA Astrophysics Data System (ADS)
The primary goal of this project was to prototype a complete Sun Synchronous Solar Powered Refrigerator. The key element to the technology is the development of the hermetic motor compressor assembly. The prototype was to be developed to either the stage where Polar Products could receive additional venture capital or to the point whereby Polar could use their own capital to manufacture the systems. Our goal was to construct a prototype which would be the next step to a proven and market ready product. To demonstrate the technology under laboratory conditions was a very minimal goal.
Huygens synchronization of two clocks
Oliveira, Henrique M.; Melo, Luís V.
2015-01-01
The synchronization of two pendulum clocks hanging from a wall was first observed by Huygens during the XVII century. This type of synchronization is observed in other areas, and is fundamentally different from the problem of two clocks hanging from a moveable base. We present a model explaining the phase opposition synchronization of two pendulum clocks in those conditions. The predicted behaviour is observed experimentally, validating the model. PMID:26204557
Huygens synchronization of two clocks.
Oliveira, Henrique M; Melo, Luís V
2015-01-01
The synchronization of two pendulum clocks hanging from a wall was first observed by Huygens during the XVII century. This type of synchronization is observed in other areas, and is fundamentally different from the problem of two clocks hanging from a moveable base. We present a model explaining the phase opposition synchronization of two pendulum clocks in those conditions. The predicted behaviour is observed experimentally, validating the model. PMID:26204557
Synchronization of fractional-order complex-valued neural networks with time delay.
Bao, Haibo; Park, Ju H; Cao, Jinde
2016-09-01
This paper deals with the problem of synchronization of fractional-order complex-valued neural networks with time delays. By means of linear delay feedback control and a fractional-order inequality, sufficient conditions are obtained to guarantee the synchronization of the drive-response systems. Numerical simulations are provided to show the effectiveness of the obtained results. PMID:27268259
Magnetically nonlinear and anisotropic iron core model of synchronous reluctance motor
NASA Astrophysics Data System (ADS)
Štumberger, G.; Štumberger, B.; Dolinar, D.
2003-01-01
The magnetically nonlinear and anisotropic iron core model of a synchronous reluctance motor (SRM) is presented. The iron core model is given by the current-dependent flux linkages and their partial derivatives. It is included in a dynamic SRM model and confirmed through the comparison of measured and calculated results in the case of current-controlled linear synchronous reluctance servomotor.
Inside black holes with synchronized hair
NASA Astrophysics Data System (ADS)
Brihaye, Yves; Herdeiro, Carlos; Radu, Eugen
2016-09-01
Recently, various examples of asymptotically flat, rotating black holes (BHs) with synchronized hair have been explicitly constructed, including Kerr BHs with scalar or Proca hair, and Myers-Perry BHs with scalar hair and a mass gap, showing there is a general mechanism at work. All these solutions have been found numerically, integrating the fully non-linear field equations of motion from the event horizon outwards. Here, we address the spacetime geometry of these solutions inside the event horizon. Firstly, we provide arguments, within linear theory, that there is no regular inner horizon for these solutions. Then, we address this question fully non-linearly, using as a tractable model five dimensional, equal spinning, Myers-Perry hairy BHs. We find that, for non-extremal solutions: (1) the inside spacetime geometry in the vicinity of the event horizon is smooth and the equations of motion can be integrated inwards; (2) before an inner horizon is reached, the spacetime curvature grows (apparently) without bound. In all cases, our results suggest the absence of a smooth Cauchy horizon, beyond which the metric can be extended, for hairy BHs with synchronized hair.
NASA Astrophysics Data System (ADS)
Michiels, Wim; Nijmeijer, Henk
2009-09-01
We consider the synchronization problem of an arbitrary number of coupled nonlinear oscillators with delays in the interconnections. The network topology is described by a directed graph. Unlike the conventional approach of deriving directly sufficient synchronization conditions, the approach of the paper starts from an exact stability analysis in a (gain, delay) parameter space of a synchronized equilibrium and extracts insights from an analysis of its bifurcations and from the corresponding emerging behavior. Instrumental to this analysis a factorization of the characteristic equation is employed that not only facilitates the analysis and reduces computational cost but also allows to determine the precise role of the individual agents and the topology of the network in the (in)stability mechanisms. The study provides an algorithm to perform a stability and bifurcation analysis of synchronized equilibria. Furthermore, it reveals fundamental limitations to synchronization and it explains under which conditions on the topology of the network and on the characteristics of the coupling the systems are expected to synchronize. In the second part of the paper the results are applied to coupled Lorenz systems. The main results show that for sufficiently large coupling gains, delay-coupled Lorenz systems exhibit a generic behavior that does not depend on the number of systems and the topology of the network, as long as some basic assumptions are satisfied, including the strong connectivity of the graph. Here the linearized stability analysis is strengthened by a nonlinear stability analysis which confirms the predictions based on the linearized stability and bifurcation analysis. This illustrates the usefulness of the exact linearized analysis in a situation where a direct nonlinear stability analysis is not possible or where it yields conservative conditions from which it is hard to get qualitative insights in the synchronization mechanisms and their scaling properties
FPGA based fast synchronous serial multi-wire links synchronization
NASA Astrophysics Data System (ADS)
Pozniak, Krzysztof T.
2013-10-01
The paper debates synchronization method of multi-wire, serial link of constant latency, by means of pseudo-random numbers generators. The solution was designed for various families of FPGA circuits. There were debated synchronization algorithm and functional structure of parameterized transmitter and receiver modules. The modules were realized in VHDL language in a behavioral form.
Design Method of ILQ Robust Current Control System for Synchronous Reluctance Electrical Motors
NASA Astrophysics Data System (ADS)
Amano, Yoko; Takami, Hiroshi; Fujii, Takao
In this paper, a robust current control system for a synchronous reluctance electrical motor by an ILQ (Inverse Linear Quadratic) design method is proposed newly. First, for performing simultaneously decouple and large region linearization of an d-q axes system in the synchronous reluctance electrical motor using nonlinear state feedback, it is derived that a linear current-voltage state equation linearized model by the d-q axes decouple of the synchronous reluctance electrical motor. Next, according to the ILQ design method, an optimum solution and an optimal condition that achieve the robust current control system for the synchronous reluctance electrical motor are analytically derived, then the robust current control system can be designed. Finally, in practical experiments, we compare the proposed method with the PI (Proportional Integral) control method, the creativity and the usefulness of the proposed method are confirmed by experimental results.
Digital synchronization and communication techniques
NASA Technical Reports Server (NTRS)
Lindsey, William C.
1992-01-01
Information on digital synchronization and communication techniques is given in viewgraph form. Topics covered include phase shift keying, modems, characteristics of open loop digital synchronizers, an open loop phase and frequency estimator, and a digital receiver structure using an open loop estimator in a decision directed architecture.
Robust Sliding Window Synchronizer Developed
NASA Technical Reports Server (NTRS)
Chun, Kue S.; Xiong, Fuqin; Pinchak, Stanley
2004-01-01
The development of an advanced robust timing synchronization scheme is crucial for the support of two NASA programs--Advanced Air Transportation Technologies and Aviation Safety. A mobile aeronautical channel is a dynamic channel where various adverse effects--such as Doppler shift, multipath fading, and shadowing due to precipitation, landscape, foliage, and buildings--cause the loss of symbol timing synchronization.
Asynchronous & Synchronous E-Learning
ERIC Educational Resources Information Center
Hrastinski, Stefan
2008-01-01
An ongoing debate addresses the usefulness of asynchronous versus synchronous e-learning. "Asynchronous e-learning," commonly facilitated by media such as e-mail and discussion boards, supports work relations among learners and with teachers, even when participants cannot be online at the same time. "Synchronous e-learning," commonly supported by…
Explosive synchronization is discontinuous
NASA Astrophysics Data System (ADS)
Vlasov, Vladimir; Zou, Yong; Pereira, Tiago
2015-07-01
Spontaneous explosive is an abrupt transition to collective behavior taking place in heterogeneous networks when the frequencies of the nodes are positively correlated with the node degree. This explosive transition was conjectured to be discontinuous. Indeed, numerical investigations reveal a hysteresis behavior associated with the transition. Here, we analyze explosive synchronization in star graphs. We show that in the thermodynamic limit the transition to (and out of) collective behavior is indeed discontinuous. The discontinuous nature of the transition is related to the nonlinear behavior of the order parameter, which in the thermodynamic limit exhibits multiple fixed points. Moreover, we unravel the hysteresis behavior in terms of the graph parameters. Our numerical results show that finite-size graphs are well described by our predictions.
Kobus, J.R.
1988-05-03
This patent describes an apparatus for synchronizing the speeds of two engines, each having its own throttle level connected by an associated cable to a respective hand throttle lever, comprising moving means carried by the throttle lever of one of the engines for moving the throttle lever of the one engine independently of its associated cable and its respective hand throttle lever to increase or decrease the speed of the one engine until the speed of the one engine matches the speed of the other engine. The moving means moves the throttle lever of the one engine without moving its associated cable or its respective hand throttle lever, and actuating means mounted remote from the throttle lever of the one engine for actuating the moving means.
Synchronization in neural nets
NASA Technical Reports Server (NTRS)
Vidal, Jacques J.; Haggerty, John
1988-01-01
The paper presents an artificial neural network concept (the Synchronizable Oscillator Networks) where the instants of individual firings in the form of point processes constitute the only form of information transmitted between joining neurons. In the model, neurons fire spontaneously and regularly in the absence of perturbation. When interaction is present, the scheduled firings are advanced or delayed by the firing of neighboring neurons. Networks of such neurons become global oscillators which exhibit multiple synchronizing attractors. From arbitrary initial states, energy minimization learning procedures can make the network converge to oscillatory modes that satisfy multi-dimensional constraints. Such networks can directly represent routing and scheduling problems that consist of ordering sequences of events.
Synchronous anorectal melanoma
Balicevic, Drinko; Tomic, Karla; Bekavac-Beslin, Miroslav; Kovacevic, Igor; Mijic, August; Belicza, Mladen; Kruslin, Bozo
2006-01-01
Anorectal melanoma is a very rare tumor with poor prognosis. Rectal bleeding is the most frequent symptom and surgical treatment ranges from local excision to radical abdominoperineal resection. We report a case of a 75-years-old male patient who presented with a history of recurrent rectal bleeding, and whose histopathological diagnosis was melanoma. Macroscopically, we found two distinct tumors in anorectal region, 0.5 cm and 1.5 cm from dentate line. The first one was pedunculated, on a thin stalk, measuring 1 cm in greatest diameter, and the second one was sessile and nodular measuring up to 2.8 cm in largest diameter. Microscopic examination and immunohistochemical analysis of both tumors confirmed the diagnosis of melanoma. This case represents multiple synchronous primary melanoma of the anorectal region, with a possibility that one of the lesions is primary melanoma and the second one is a satellite lesion. PMID:16733870
Byzantine-fault tolerant self-stabilizing protocol for distributed clock synchronization systems
NASA Technical Reports Server (NTRS)
Malekpour, Mahyar R. (Inventor)
2010-01-01
A rapid Byzantine self-stabilizing clock synchronization protocol that self-stabilizes from any state, tolerates bursts of transient failures, and deterministically converges within a linear convergence time with respect to the self-stabilization period. Upon self-stabilization, all good clocks proceed synchronously. The Byzantine self-stabilizing clock synchronization protocol does not rely on any assumptions about the initial state of the clocks. Furthermore, there is neither a central clock nor an externally generated pulse system. The protocol converges deterministically, is scalable, and self-stabilizes in a short amount of time. The convergence time is linear with respect to the self-stabilization period.
Robustness to noise in synchronization of complex networks
NASA Astrophysics Data System (ADS)
Buscarino, Arturo; Gambuzza, Lucia Valentina; Porfiri, Maurizio; Fortuna, Luigi; Frasca, Mattia
2013-06-01
In this report, we investigate dynamical robustness of a complex network to noise injected through one of its nodes. We focus on synchronization of coupled nonlinear systems and, as a special instance, we address the classical consensus protocol for linear integrators. We establish an exact closed-form expression of the synchronization error for the consensus protocol and an approximate result for chaotic units. While structural robustness is known to be significantly affected by attacks targeted to network hubs, our results posit that dynamical robustness is controlled by both the topology of the network and the dynamics of the units. We provide examples where hubs perform better or worse than isolated nodes.
Synchronized defibrillation for ventricular fibrillation
Manoharan, Ganesh; Navarro, Cesar; Walsh, Simon J; Allen, John D; Anderson, John McC; Adgey, AA Jennifer
2012-01-01
Objective: Optimization of defibrillation success is important to improve efficacy and minimize post-shock sequelae. Previous work has suggested an improvement in shock success when an intracardiac shock is delivered synchronized to the upslope of a VF wave. We investigated the efficacy of transthoracic defibrillation success using a novel external biphasic defibrillator which delivers shocks synchronized to the upslope of the surface ECG. Methods: A prospective, controlled, randomized study in a research institute laboratory of male and female pigs (54.2±1.8 kg). Ventricular fibrillation (VF) was induced in 10 anaesthetized and ventilated pigs. Shocks were delivered randomly from a biphasic defibrillator in synchronized or non-synchronized mode via self-adhesive electrode pads following 30 s of VF. Energy settings at 50, 70, 80, and 100J were randomly tested. VF amplitude, impedance, and shock outcome were recorded and analysed digitally. Results: A total of 300 shocks were delivered. Synchronized shocks were delivered on the upslope of the VF wave in 99% of cases. There was no significant difference in shock success between shocks delivered in synchronized or non-synchronized modes (p=0.695). There was no significant difference in the amplitude of VF between successful and unsuccessful shocks (p=0.163). Furthermore, there was no association between shock success and transthoracic impedance. Conclusion: The novel defibrillator used in this study was able to consistently deliver shocks on the upslope portion of the VF wave but did not show an improvement in shock success. PMID:24062919
Nutritional recommendations for synchronized swimming.
Robertson, Sherry; Benardot, Dan; Mountjoy, Margo
2014-08-01
The sport of synchronized swimming is unique, because it combines speed, power, and endurance with precise synchronized movements and high-risk acrobatic maneuvers. Athletes must train and compete while spending a great amount of time underwater, upside down, and without the luxury of easily available oxygen. This review assesses the scientific evidence with respect to the physiological demands, energy expenditure, and body composition in these athletes. The role of appropriate energy requirements and guidelines for carbohydrate, protein, fat, and micronutrients for elite synchronized swimmers are reviewed. Because of the aesthetic nature of the sport, which prioritizes leanness, the risks of energy and macronutrient deficiencies are of significant concern. Relative Energy Deficiency in Sport and disordered eating/eating disorders are also of concern for these female athletes. An approach to the healthy management of body composition in synchronized swimming is outlined. Synchronized swimmers should be encouraged to consume a well-balanced diet with sufficient energy to meet demands and to time the intake of carbohydrate, protein, and fat to optimize performance and body composition. Micronutrients of concern for this female athlete population include iron, calcium, and vitamin D. This article reviews the physiological demands of synchronized swimming and makes nutritional recommendations for recovery, training, and competition to help optimize athletic performance and to reduce risks for weight-related medical issues that are of particular concern for elite synchronized swimmers. PMID:24667278
Interaction Patterns in Synchronous Online Calculus and Linear Algebra Recitations
ERIC Educational Resources Information Center
Mayer, Greg; Hendricks, Cher
2014-01-01
This study describes interaction patterns observed during a pilot project that explored the use of web-conferencing (WC) software in two undergraduate distance education courses offered to advanced high-school students. The pilot program replaced video-conferencing technology with WC software during recitations, so as to increase participation in…
Banks, R.M.
1986-01-14
This patent describes a linear output nitinol engine consisting of a number of integrated communicating parts. The engine has an external support framework which is described in detail. The patent further describes a wire transport mechanism, a pair of linkage levers with a loom secured to them, a number of nitinol wires strung between the looms, and a power takeoff block secured to the linkage levers. A pulley positioned in a flip-flop supporting bracket and a power takeoff modality including a tension member connected to a power output cable in order to provide linear power output transmission is described. A method for biasing the timing and the mechanism for timing the synchronization of the throw over arms and the flip-flop of the pulley are also described.
Synchronization in an evolving network
NASA Astrophysics Data System (ADS)
Singh, R. K.; Bagarti, Trilochan
2015-09-01
In this work we study the dynamics of Kuramoto oscillators on a stochastically evolving network whose evolution is governed by the phases of the individual oscillators and degree distribution. Synchronization is achieved after a threshold connection density is reached. This cumulative effect of topology and dynamics has many real-world implications, where synchronization in a system emerges as a collective property of its components in a self-organizing manner. The synchronous state remains stable as long as the connection density remains above the threshold value, with additional links providing resilience against network fluctuations.
Time synchronized video systems
NASA Technical Reports Server (NTRS)
Burnett, Ron
1994-01-01
The idea of synchronizing multiple video recordings to some type of 'range' time has been tried to varying degrees of success in the past. Combining this requirement with existing time code standards (SMPTE) and the new innovations in desktop multimedia however, have afforded an opportunity to increase the flexibility and usefulness of such efforts without adding costs over the traditional data recording and reduction systems. The concept described can use IRIG, GPS or a battery backed internal clock as the master time source. By converting that time source to Vertical Interval Time Code or Longitudinal Time Code, both in accordance with the SMPTE standards, the user will obtain a tape that contains machine/computer readable time code suitable for use with editing equipment that is available off-the-shelf. Accuracy on playback is then determined by the playback system chosen by the user. Accuracies of +/- 2 frames are common among inexpensive systems and complete frame accuracy is more a matter of the users' budget than the capability of the recording system.
Optimistic barrier synchronization. Contractor report
Nicol, D.M.
1992-07-01
Barrier synchronization is a fundamental operation in parallel computation. In many contexts, at the point a processor enters a barrier it knows that is has already processed all work required of it prior to the synchronization. This paper treats the alternative case, when a processor cannot enter a barrier with the assurance that it has already performed all necessary pre-synchronization computation. The proble marises when the number of pre-synchronization messages to be received by a processor is unknown, for example, in a parallel discrete simulation or any other computation that is largely driven by an unpredictable exchange of messages. The authors describe an optimistic O(log2P) barrier algorithm for such problems, study its performance on a large-scale parallel system, and consider extensions to general associative reductions, as well as associative parallel prefix computations.
Generic Conditions for Hydrodynamic Synchronization
NASA Astrophysics Data System (ADS)
Uchida, Nariya; Golestanian, Ramin
2011-02-01
Synchronization of actively oscillating organelles such as cilia and flagella facilitates self-propulsion of cells and pumping fluid in low Reynolds number environments. To understand the key mechanism behind synchronization induced by hydrodynamic interaction, we study a model of rigid-body rotors making fixed trajectories of arbitrary shape under driving forces that are arbitrary functions of the phase. For a wide class of geometries, we obtain the necessary and sufficient conditions for synchronization of a pair of rotors. We also find a novel synchronized pattern with an oscillating phase shift. Our results shed light on the role of hydrodynamic interactions in biological systems, and could help in developing efficient mixing and transport strategies in microfluidic devices.
Synchronous motion modulates animacy perception.
Takahashi, Kohske; Watanabe, Katsumi
2015-01-01
Visual motion serves as a cue for high-level percepts. The present study reports novel modulation of animacy perception through synchronous motion. A target dot moving along a random trajectory was presented. The trajectory was generated based on a variant of 1/f noise; hence, the dot could be perceived as animate. Participants were asked to rate the strength of perceived animacy and perceived intention from the target dot. Several task-irrelevant dots surrounding the target were also presented. Results indicated that perceived animacy and intention were drastically weakened when surrounding dots created synchronous motion with the target dot as compared to when surrounding dots did not create synchronous motion. A series of follow-up experiments replicated these results and revealed specific characteristics of this modulation. The present findings suggest synchronous visual motion serves as a strong modulator of animacy perception. PMID:26114680
Synchronous identification of friendly targets
Telle, John M.; Roger, Stutz A.
1998-01-01
A synchronous communication targeting system for use in battle. The present invention includes a transceiver having a stabilizing oscillator, a synchronous amplifier and an omnidirectional receiver, all in electrical communication with each other. A remotely located beacon is attached to a blackbody radiation source and has an amplitude modulator in electrical communication with a optical source. The beacon's amplitude modulator is set so that the optical source transmits radiation frequency at approximately the same or lower amplitude than that of the blackbody radiation source to which the beacon is attached. The receiver from the transceiver is adapted to receive frequencies approximately at or below blackbody radiation signals and sends such signals to the synchronous amplifier. The synchronous amplifier then rectifies and amplifies those signals which correspond to the predetermined frequency to therefore identify whether the blackbody radiation source is friendly or not.
Synchronization by small time delays
NASA Astrophysics Data System (ADS)
Pruessner, G.; Cheang, S.; Jensen, H. J.
2015-02-01
Synchronization is a phenomenon observed in all of the living and in much of the non-living world, for example in the heart beat, Huygens' clocks, the flashing of fireflies and the clapping of audiences. Depending on the number of degrees of freedom involved, different mathematical approaches have been used to describe it, most prominently integrate-and-fire oscillators and the Kuramoto model of coupled oscillators. In the present work, we study a very simple and general system of smoothly evolving oscillators, which continue to interact even in the synchronized state. We find that under very general circumstances, synchronization generically occurs in the presence of a (small) time delay. Strikingly, the synchronization time is inversely proportional to the time delay.
Anticipated synchronization in coupled complex Ginzburg-Landau systems.
Ciszak, Marzena; Mayol, Catalina; Mirasso, Claudio R; Toral, Raul
2015-09-01
We study the occurrence of anticipated synchronization in two complex Ginzburg-Landau systems coupled in a master-slave configuration. Master and slave systems are ruled by the same autonomous function, but the slave system receives the injection from the master and is subject to a negative delayed self-feedback loop. We give evidence that the magnitude of the largest anticipation time, obtained for complex-valued coupling constants, depends on the dynamical regime where the system operates (defect turbulence, phase turbulence, or bichaos) and scales with the linear autocorrelation time of the system. We also provide analytical conditions for the stability of the anticipated synchronization manifold that are in qualitative agreement with those obtained numerically. Finally, we report on the existence of anticipated synchronization in coupled two-dimensional complex Ginzburg-Landau systems. PMID:26465544
Anticipated synchronization in coupled complex Ginzburg-Landau systems
NASA Astrophysics Data System (ADS)
Ciszak, Marzena; Mayol, Catalina; Mirasso, Claudio R.; Toral, Raul
2015-09-01
We study the occurrence of anticipated synchronization in two complex Ginzburg-Landau systems coupled in a master-slave configuration. Master and slave systems are ruled by the same autonomous function, but the slave system receives the injection from the master and is subject to a negative delayed self-feedback loop. We give evidence that the magnitude of the largest anticipation time, obtained for complex-valued coupling constants, depends on the dynamical regime where the system operates (defect turbulence, phase turbulence, or bichaos) and scales with the linear autocorrelation time of the system. We also provide analytical conditions for the stability of the anticipated synchronization manifold that are in qualitative agreement with those obtained numerically. Finally, we report on the existence of anticipated synchronization in coupled two-dimensional complex Ginzburg-Landau systems.
Emergence of nonuniform V-states by synchronization
NASA Astrophysics Data System (ADS)
Friedland, L.; Shagalov, A. G.
2002-09-01
It is shown that a family of nonuniform, m-fold symmetric rotating vortex structures in two dimensions (nonuniform V-states) can emerge in both free and bounded space by subjecting an axisymmetric vortex with a sharp vorticity edge to external rotation and weak strain of appropriate symmetry. The phenomenon is due to nonlinear synchronization (autoresonance) in the system, as the vorticity distribution of the vortex structure self-adjusts to phase lock with slowly varying external rotation. The synchronization is induced by passage through resonance with the isolated eigenmode of the linearized problem, provided the external strain rate is above a threshold. Synchronized, m=2 nonuniform V-states remain stable after the external strain is switched off. Free m=3 and 4 states, in contrast, are destroyed via three-wave decay at later times. The negative feedback approach is proposed to stabilize this instability.
A synchronous phase detection system for an optical interferometric sensor
NASA Astrophysics Data System (ADS)
Bush, I. J.
1982-05-01
A system has been developed to accurately detect phase produced in optical interferometric sensors. The system employs optical heterodyning, and it synchronously detects optical phase by feeding an error signal back to a phase modulator in the reference leg of the interferometer. This system is seen to have properties similar to a phase-locked loop used for the demodulation of FM signals. The system model is second order and nonlinear, but a linear approximation serves to accurately describe the system in synchronous operation and is corroborated with well-matched empirical data. The complete model is simulated via computer techniques and is needed to describe the system's parameters that lead to loss and reacquisition of synchronization.
Event-Synchronous Analysis for Connected-Speech Recognition.
NASA Astrophysics Data System (ADS)
Morgan, David Peter
The motivation for event-synchronous speech analysis originates from linear system theory where the speech-source transfer function is excited by an impulse-like driving function. In speech processing, the impulse response obtained from this linear system contains both semantic information and the vocal tract transfer function. Typically, an estimate of the transfer function is obtained via the spectrum by assuming a short-time stationary signal within some analysis window. However, this spectrum is often distorted by the periodic effects which occur when multiple (pitch) impulses are included in the analysis window. One method to remove these effects would be to deconvolve the excitation function from the speech signal to obtain the transfer function. The more attractive approach is to locate and identify the excitation function and synchronize the analysis frame with it. Event-synchronous analysis differs from pitch -synchronous analysis in that there are many events useful for speech recognition which are not pitch excited. In addition, event-synchronous analysis locates the important boundaries between speech events, such as voiced to unvoiced and silence to burst transitions. In asynchronous processing, an analysis frame which contains portions of two adjacent but dissimilar speech events is often so ambiguous as to distort or mask the important "phonetic" features of both events. Thus event-syncronous processing is employed to obtain an accurate spectral estimate and in turn enhance the estimate of the vocal-tract transfer function. Among the issues which have been addressed in implementing an event-synchronous recognition system are those of developing robust event (pitch, burst, etc.) detectors, synchronous-analysis methodologies, more meaningful feature sets, and dynamic programming algorithms for nonlinear time alignment. An advantage of event-synchronous processing is that the improved representation of the transfer function creates an opportunity for
Synchronizing Rotation Of A Heavy Load
NASA Technical Reports Server (NTRS)
Ratliff, Roger
1991-01-01
Drive system rotates large-inertia load at constant low speed. Simple setup of motors, pulleys, and belts provides both torque and synchronism. Induction motor drives two loads: rotating instrument and slightly lagging synchronous motor. Provides ample torque to start and maintain rotation, and synchronous motor ensures rotation synchronized with ac power supply.
Synchronous reactive programming in Ptolemy
Boulanger, F.; Vidal-Naquet, G.
1996-12-31
Synchronous reactive languages allow a high level deterministic description of reactive systems such as control-command systems. Their well defined mathematical semantics makes it possible to check formal properties on the control of a system. In previous work, we developed an object-oriented execution model for synchronous reactive modules. This model is implemented as a set of tools and a C++ class library, and allows us to use object-oriented methodologies and tools for the design of complex applications with both transformational and reactive parts. Among these design tools, the Ptolemy system stands as an object-oriented framework that supports various execution models, or {open_quotes}domains{close_quotes}. We are currently working on a translator from the output format of the Lustre and Esterel compilers to the Ptolemy language. Since no existing domain matches the reactive synchronous execution model, we also plan to develop a SEC (Synchronous Execution and Communication) domain. Such a domain will provide support for the execution of synchronous modules in Ptolemy. One of the most interesting features of Ptolemy is the communication between domains. Therefore we discuss the interface of the SEC domain to other domains to determine the meaning of communications between them. The main goal is to allow the use of synchronous reactive modules for the control of the behavior of data-flow or discrete event processes.
RB Particle Filter Time Synchronization Algorithm Based on the DPM Model.
Guo, Chunsheng; Shen, Jia; Sun, Yao; Ying, Na
2015-01-01
Time synchronization is essential for node localization, target tracking, data fusion, and various other Wireless Sensor Network (WSN) applications. To improve the estimation accuracy of continuous clock offset and skew of mobile nodes in WSNs, we propose a novel time synchronization algorithm, the Rao-Blackwellised (RB) particle filter time synchronization algorithm based on the Dirichlet process mixture (DPM) model. In a state-space equation with a linear substructure, state variables are divided into linear and non-linear variables by the RB particle filter algorithm. These two variables can be estimated using Kalman filter and particle filter, respectively, which improves the computational efficiency more so than if only the particle filter was used. In addition, the DPM model is used to describe the distribution of non-deterministic delays and to automatically adjust the number of Gaussian mixture model components based on the observational data. This improves the estimation accuracy of clock offset and skew, which allows achieving the time synchronization. The time synchronization performance of this algorithm is also validated by computer simulations and experimental measurements. The results show that the proposed algorithm has a higher time synchronization precision than traditional time synchronization algorithms. PMID:26404291
RB Particle Filter Time Synchronization Algorithm Based on the DPM Model
Guo, Chunsheng; Shen, Jia; Sun, Yao; Ying, Na
2015-01-01
Time synchronization is essential for node localization, target tracking, data fusion, and various other Wireless Sensor Network (WSN) applications. To improve the estimation accuracy of continuous clock offset and skew of mobile nodes in WSNs, we propose a novel time synchronization algorithm, the Rao-Blackwellised (RB) particle filter time synchronization algorithm based on the Dirichlet process mixture (DPM) model. In a state-space equation with a linear substructure, state variables are divided into linear and non-linear variables by the RB particle filter algorithm. These two variables can be estimated using Kalman filter and particle filter, respectively, which improves the computational efficiency more so than if only the particle filter was used. In addition, the DPM model is used to describe the distribution of non-deterministic delays and to automatically adjust the number of Gaussian mixture model components based on the observational data. This improves the estimation accuracy of clock offset and skew, which allows achieving the time synchronization. The time synchronization performance of this algorithm is also validated by computer simulations and experimental measurements. The results show that the proposed algorithm has a higher time synchronization precision than traditional time synchronization algorithms. PMID:26404291
Direct evidence of flagellar synchronization through hydrodynamic interactions
NASA Astrophysics Data System (ADS)
Brumley, Douglas; Polin, Marco; Wan, Kirsty; Goldstein, Raymond
2013-11-01
Eukaryotic cilia and flagella exhibit striking coordination, from the synchronous beating of two flagella in Chlamydomonas to the metachronal waves and large-scale flows displayed by carpets of cilia. However, the precise mechanisms responsible for flagellar synchronization remain unclear. We perform a series of experiments involving two individual flagella in a quiescent fluid. Cells are isolated from the colonial alga Volvox carteri, held in place at a fixed distance d, and oriented so that their flagellar beating planes coincide. In this fashion, we are able to explicitly assess the role of hydrodynamics in achieving synchronization. For closely separated cells, the flagella are capable of exhibiting a phase-locked state for thousands of beats at a time, despite significant differences in their intrinsic frequencies. For intermediate values of d, synchronous periods are interrupted by brief phase slips, while for d >> 1 the flagellar phase difference drifts almost linearly with time. The coupling strength extracted through analysis of the synchronization statistics exhibits excellent agreement with hydrodynamic predictions. This study unambiguously reveals that flagella coupled only through hydrodynamics are capable of exhibiting robust synchrony.
Synchronization in Complex Oscillator Networks and Smart Grids
Dorfler, Florian; Chertkov, Michael; Bullo, Francesco
2012-07-24
The emergence of synchronization in a network of coupled oscillators is a fascinating topic in various scientific disciplines. A coupled oscillator network is characterized by a population of heterogeneous oscillators and a graph describing the interaction among them. It is known that a strongly coupled and sufficiently homogeneous network synchronizes, but the exact threshold from incoherence to synchrony is unknown. Here we present a novel, concise, and closed-form condition for synchronization of the fully nonlinear, non-equilibrium, and dynamic network. Our synchronization condition can be stated elegantly in terms of the network topology and parameters, or equivalently in terms of an intuitive, linear, and static auxiliary system. Our results significantly improve upon the existing conditions advocated thus far, they are provably exact for various interesting network topologies and parameters, they are statistically correct for almost all networks, and they can be applied equally to synchronization phenomena arising in physics and biology as well as in engineered oscillator networks such as electric power networks. We illustrate the validity, the accuracy, and the practical applicability of our results in complex networks scenarios and in smart grid applications.
Synchronization in complex oscillator networks and smart grids.
Dörfler, Florian; Chertkov, Michael; Bullo, Francesco
2013-02-01
The emergence of synchronization in a network of coupled oscillators is a fascinating topic in various scientific disciplines. A widely adopted model of a coupled oscillator network is characterized by a population of heterogeneous phase oscillators, a graph describing the interaction among them, and diffusive and sinusoidal coupling. It is known that a strongly coupled and sufficiently homogeneous network synchronizes, but the exact threshold from incoherence to synchrony is unknown. Here, we present a unique, concise, and closed-form condition for synchronization of the fully nonlinear, nonequilibrium, and dynamic network. Our synchronization condition can be stated elegantly in terms of the network topology and parameters or equivalently in terms of an intuitive, linear, and static auxiliary system. Our results significantly improve upon the existing conditions advocated thus far, they are provably exact for various interesting network topologies and parameters; they are statistically correct for almost all networks; and they can be applied equally to synchronization phenomena arising in physics and biology as well as in engineered oscillator networks, such as electrical power networks. We illustrate the validity, the accuracy, and the practical applicability of our results in complex network scenarios and in smart grid applications. PMID:23319658
Synchronization in complex oscillator networks and smart grids
Dörfler, Florian; Chertkov, Michael; Bullo, Francesco
2013-01-01
The emergence of synchronization in a network of coupled oscillators is a fascinating topic in various scientific disciplines. A widely adopted model of a coupled oscillator network is characterized by a population of heterogeneous phase oscillators, a graph describing the interaction among them, and diffusive and sinusoidal coupling. It is known that a strongly coupled and sufficiently homogeneous network synchronizes, but the exact threshold from incoherence to synchrony is unknown. Here, we present a unique, concise, and closed-form condition for synchronization of the fully nonlinear, nonequilibrium, and dynamic network. Our synchronization condition can be stated elegantly in terms of the network topology and parameters or equivalently in terms of an intuitive, linear, and static auxiliary system. Our results significantly improve upon the existing conditions advocated thus far, they are provably exact for various interesting network topologies and parameters; they are statistically correct for almost all networks; and they can be applied equally to synchronization phenomena arising in physics and biology as well as in engineered oscillator networks, such as electrical power networks. We illustrate the validity, the accuracy, and the practical applicability of our results in complex network scenarios and in smart grid applications. PMID:23319658
Synchronization configurations of two coupled double pendula
NASA Astrophysics Data System (ADS)
Koluda, Piotr; Perlikowski, Przemyslaw; Czolczynski, Krzysztof; Kapitaniak, Tomasz
2014-04-01
We consider the synchronization of two self-excited double pendula hanging from a horizontal beam which can roll on the parallel surface. We show that such pendula can obtain four different robust synchronous configurations. Our approximate analytical analysis allows to derive the synchronization conditions and explains the observed types of synchronizations. We consider the energy balance in the system and show how the energy is transferred between the pendula via the oscillating beam allowing the pendula' synchronization.
Sidorin, Anatoly
2010-01-05
In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.
NASA Astrophysics Data System (ADS)
Sidorin, Anatoly
2010-01-01
In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.
Synchronization of phase oscillators with frequency-weighted coupling
NASA Astrophysics Data System (ADS)
Xu, Can; Sun, Yuting; Gao, Jian; Qiu, Tian; Zheng, Zhigang; Guan, Shuguang
2016-02-01
Recently, the first-order synchronization transition has been studied in systems of coupled phase oscillators. In this paper, we propose a framework to investigate the synchronization in the frequency-weighted Kuramoto model with all-to-all couplings. A rigorous mean-field analysis is implemented to predict the possible steady states. Furthermore, a detailed linear stability analysis proves that the incoherent state is only neutrally stable below the synchronization threshold. Nevertheless, interestingly, the amplitude of the order parameter decays exponentially (at least for short time) in this regime, resembling the Landau damping effect in plasma physics. Moreover, the explicit expression for the critical coupling strength is determined by both the mean-field method and linear operator theory. The mechanism of bifurcation for the incoherent state near the critical point is further revealed by the amplitude expansion theory, which shows that the oscillating standing wave state could also occur in this model for certain frequency distributions. Our theoretical analysis and numerical results are consistent with each other, which can help us understand the synchronization transition in general networks with heterogenous couplings.
Synchronization of phase oscillators with frequency-weighted coupling.
Xu, Can; Sun, Yuting; Gao, Jian; Qiu, Tian; Zheng, Zhigang; Guan, Shuguang
2016-01-01
Recently, the first-order synchronization transition has been studied in systems of coupled phase oscillators. In this paper, we propose a framework to investigate the synchronization in the frequency-weighted Kuramoto model with all-to-all couplings. A rigorous mean-field analysis is implemented to predict the possible steady states. Furthermore, a detailed linear stability analysis proves that the incoherent state is only neutrally stable below the synchronization threshold. Nevertheless, interestingly, the amplitude of the order parameter decays exponentially (at least for short time) in this regime, resembling the Landau damping effect in plasma physics. Moreover, the explicit expression for the critical coupling strength is determined by both the mean-field method and linear operator theory. The mechanism of bifurcation for the incoherent state near the critical point is further revealed by the amplitude expansion theory, which shows that the oscillating standing wave state could also occur in this model for certain frequency distributions. Our theoretical analysis and numerical results are consistent with each other, which can help us understand the synchronization transition in general networks with heterogeneous couplings. PMID:26903110
Synchronization of phase oscillators with frequency-weighted coupling
Xu, Can; Sun, Yuting; Gao, Jian; Qiu, Tian; Zheng, Zhigang; Guan, Shuguang
2016-01-01
Recently, the first-order synchronization transition has been studied in systems of coupled phase oscillators. In this paper, we propose a framework to investigate the synchronization in the frequency-weighted Kuramoto model with all-to-all couplings. A rigorous mean-field analysis is implemented to predict the possible steady states. Furthermore, a detailed linear stability analysis proves that the incoherent state is only neutrally stable below the synchronization threshold. Nevertheless, interestingly, the amplitude of the order parameter decays exponentially (at least for short time) in this regime, resembling the Landau damping effect in plasma physics. Moreover, the explicit expression for the critical coupling strength is determined by both the mean-field method and linear operator theory. The mechanism of bifurcation for the incoherent state near the critical point is further revealed by the amplitude expansion theory, which shows that the oscillating standing wave state could also occur in this model for certain frequency distributions. Our theoretical analysis and numerical results are consistent with each other, which can help us understand the synchronization transition in general networks with heterogenous couplings. PMID:26903110
Synchronous Bilateral Breast Cancers
Subramanyan, Annapurneswari; Radhakrishna, Selvi
2015-01-01
Background Bilateral breast cancer (BBC) is not an uncommon entity in contemporary breast clinics. Improved life expectancy after breast cancer treatment and routine use of contra-lateral breast mammography has led to increased incidence of BBC. Our study objective was to define the epidemiological and tumour characteristics of BBC in India. Materials and Methods A total of 1251 breast cancer patients were treated during the period January 2007 to March 2015 and 30 patients were found to have BBC who constituted the study population (60 tumour samples). Synchronous bilateral breast cancers (SBC) was defined as two tumours diagnosed within an interval of 6 months and a second cancer diagnosed after 6 months was labelled as metachronous breast cancer (MBC). Analyses of patient and tumour characteristics were done in this prospective data base of BBC patients. Results Median patient age was 66 years (range 39-85). Majority of the patients had SBC (n=28) and in 12 patients the second tumour was clinically occult and detected only by mammography of the contra-lateral breast. The second tumour was found at lower tumour size compared to the first in 73% of cases and was negative for axillary metastasis in 80% of cases (24/30). Infiltrating ductal carcinoma was the commonest histological type (n=51) and majority of the tumours were ER/PR positive (50/60). Her2 was overexpressed in 13 tumours (21%). Over 70% (22/30) of patients had similar histology in both breasts and amongst them grade concordance was present in about 69% (15/22) of patients. Concordance rates of ER, PR and Her2 statuses were 83%, 80% and 90% respectively. Bilateral mastectomy was the commonest surgery performed in 80% of the patients followed by bilateral breast conservation in 13%. At the end of study period, 26 patients were alive and disease free. Median survival was 29 months (range 3-86 months). Conclusion In most patients with BBC, the second tumour is identified at an early stage than index
Synchronized flutter of two slender flags
NASA Astrophysics Data System (ADS)
Mougel, Jérôme; Doaré, Olivier; Michelin, Sébastien
2016-08-01
The interactions and synchronization of two parallel and slender flags in a uniform axial flow are studied in the present paper by generalizing Lighthill's Elongated Body Theory (EBT) and Lighthill's Large Amplitude Elongated Body Theory (LAEBT) to account for the hydrodynamic coupling between flags. The proposed method consists in two successive steps, namely the reconstruction of the flow created by a flapping flag within the LAEBT framework and the computation of the fluid force generated by this nonuniform flow on the second flag. In the limit of slender flags in close proximity, we show that the effect of the wakes have little influence on the long time coupled-dynamics and can be neglected in the modeling. This provides a simplified framework extending LAEBT to the coupled dynamics of two flags. Using this simplified model, both linear and large amplitude results are reported to explore the selection of the flapping regime as well as the dynamical properties of two side-by-side slender flags. Hydrodynamic coupling of the two flags is observed to destabilize the flags for most parameters, and to induce a long-term synchronization of the flags, either in-phase or out-of-phase.
Bodily synchronization underlying joke telling
Schmidt, R. C.; Nie, Lin; Franco, Alison; Richardson, Michael J.
2014-01-01
Advances in video and time series analysis have greatly enhanced our ability to study the bodily synchronization that occurs in natural interactions. Past research has demonstrated that the behavioral synchronization involved in social interactions is similar to dynamical synchronization found generically in nature. The present study investigated how the bodily synchronization in a joke telling task is spread across different nested temporal scales. Pairs of participants enacted knock–knock jokes and times series of their bodily activity were recorded. Coherence and relative phase analyses were used to evaluate the synchronization of bodily rhythms for the whole trial as well as at the subsidiary time scales of the whole joke, the setup of the punch line, the two-person exchange and the utterance. The analyses revealed greater than chance entrainment of the joke teller’s and joke responder’s movements at all time scales and that the relative phasing of the teller’s movements led those of the responder at the longer time scales. Moreover, this entrainment was greater when visual information about the partner’s movements was present but was decreased particularly at the shorter time scales when explicit gesturing in telling the joke was performed. In short, the results demonstrate that a complex interpersonal bodily “dance” occurs during structured conversation interactions and that this “dance” is constructed from a set of rhythms associated with the nested behavioral structure of the interaction. PMID:25177287
Modeling walker synchronization on the Millennium Bridge.
Eckhardt, Bruno; Ott, Edward; Strogatz, Steven H; Abrams, Daniel M; McRobie, Allan
2007-02-01
On its opening day the London Millennium footbridge experienced unexpected large amplitude wobbling subsequent to the migration of pedestrians onto the bridge. Modeling the stepping of the pedestrians on the bridge as phase oscillators, we obtain a model for the combined dynamics of people and the bridge that is analytically tractable. It provides predictions for the phase dynamics of individual walkers and for the critical number of people for the onset of oscillations. Numerical simulations and analytical estimates reproduce the linear relation between pedestrian force and bridge velocity as observed in experiments. They allow prediction of the amplitude of bridge motion, the rate of relaxation to the synchronized state and the magnitude of the fluctuations due to a finite number of people. PMID:17358316
Modeling walker synchronization on the Millennium Bridge
NASA Astrophysics Data System (ADS)
Eckhardt, Bruno; Ott, Edward; Strogatz, Steven H.; Abrams, Daniel M.; McRobie, Allan
2007-02-01
On its opening day the London Millennium footbridge experienced unexpected large amplitude wobbling subsequent to the migration of pedestrians onto the bridge. Modeling the stepping of the pedestrians on the bridge as phase oscillators, we obtain a model for the combined dynamics of people and the bridge that is analytically tractable. It provides predictions for the phase dynamics of individual walkers and for the critical number of people for the onset of oscillations. Numerical simulations and analytical estimates reproduce the linear relation between pedestrian force and bridge velocity as observed in experiments. They allow prediction of the amplitude of bridge motion, the rate of relaxation to the synchronized state and the magnitude of the fluctuations due to a finite number of people.
Digital data detection and synchronization
NASA Technical Reports Server (NTRS)
Noack, T. L.; Morris, J. F.
1973-01-01
The primary accomplishments have been in the analysis and simulation of receivers and bit synchronizers. It has been discovered that tracking rate effects play, a rather fundamental role in both receiver and synchronizer performance, but that data relating to recorder time-base-error, for the proper characterization of this phenomenon, is in rather short supply. It is possible to obtain operationally useful tape recorder time-base-error data from high signal-to-noise ratio tapes using synchronizers with relatively wideband tracking loops. Low signal-to-noise ratio tapes examined in the same way would not be synchronizable. Additional areas of interest covered are receiver false lock, cycle slipping, and other unusual phenomena, which have been described to some extent in this and earlier reports and simulated during the study.
Chaotic synchronization system and electrocardiogram
NASA Astrophysics Data System (ADS)
Pei, Liuqing; Dai, Xinlai; Li, Baodong
1997-01-01
A mathematical model of chaotic synchronization of the heart-blood flow coupling dynamics is proposed, which is based on a seven dimension nonlinear dynamical system constructed by three subsystems of the sinoatrial node natural pacemaker, the cardiac relaxation oscillator and the dynamics of blood-fluid in heart chambers. The existence and robustness of the self-chaotic synchronization of the system are demonstrated by both methods of theoretical analysis and numerical simulation. The spectrum of Lyapunov exponent, the Lyapunov dimension and the Kolmogorov entropy are estimated when the system was undergoing the state of self-chaotic synchronization evolution. The time waveform of the dynamical variable, which represents the membrane potential of the cardiac integrative cell, shows a shape which is similar to that of the normal electrocardiogram (ECG) of human, thus implies that the model possesses physiological significance functionally.
Remote synchronization in star networks
NASA Astrophysics Data System (ADS)
Bergner, A.; Frasca, M.; Sciuto, G.; Buscarino, A.; Ngamga, E. J.; Fortuna, L.; Kurths, J.
2012-02-01
We study phase synchronization in a network motif with a starlike structure in which the central node's (the hub's) frequency is strongly detuned against the other peripheral nodes. We find numerically and experimentally a regime of remote synchronization (RS), where the peripheral nodes form a phase synchronized cluster, while the hub remains free with its own dynamics and serves just as a transmitter for the other nodes. We explain the mechanism for this RS by the existence of a free amplitude and also show that systems with a fixed or constant amplitude, such as the classic Kuramoto phase oscillator, are not able to generate this phenomenon. Further, we derive an analytic expression which supports our explanation of the mechanism.
NASA Astrophysics Data System (ADS)
Yang, Dong-Sheng; Liu, Zhen-Wei; Zhao, Yan; Liu, Zhao-Bing
2012-04-01
The networked synchronization problem of a class of master-slave chaotic systems with time-varying communication topologies is investigated in this paper. Based on algebraic graph theory and matrix theory, a simple linear state feedback controller is designed to synchronize the master chaotic system and the slave chaotic systems with a time-varying communication topology connection. The exponential stability of the closed-loop networked synchronization error system is guaranteed by applying Lyapunov stability theory. The derived novel criteria are in the form of linear matrix inequalities (LMIs), which are easy to examine and tremendously reduce the computation burden from the feedback matrices. This paper provides an alternative networked secure communication scheme which can be extended conveniently. An illustrative example is given to demonstrate the effectiveness of the proposed networked synchronization method.
Forced synchronization of quasiperiodic oscillations
NASA Astrophysics Data System (ADS)
Stankevich, N. V.; Kurths, J.; Kuznetsov, A. P.
2015-01-01
A model of a generator of quasiperiodic oscillations forced by a periodic pulse sequence is studied. We analyze synchronization when the autonomous generator demonstrates periodic, quasiperiodic, respective weakly chaotic oscillations. For the forced quasiperiodic oscillations a picture of synchronization, consisting of small-scale and large-scale structures was uncovered. It even includes the existence of stable the three-frequency tori. For the regime of weak chaos a partial destruction of this features and of the regime of three-frequency tori are found.
Cooperative Synchronization in Wireless Networks
NASA Astrophysics Data System (ADS)
Etzlinger, Bernhard; Wymeersch, Henk; Springer, Andreas
2014-06-01
Synchronization is a key functionality in wireless network, enabling a wide variety of services. We consider a Bayesian inference framework whereby network nodes can achieve phase and skew synchronization in a fully distributed way. In particular, under the assumption of Gaussian measurement noise, we derive two message passing methods (belief propagation and mean field), analyze their convergence behavior, and perform a qualitative and quantitative comparison with a number of competing algorithms. We also show that both methods can be applied in networks with and without master nodes. Our performance results are complemented by, and compared with, the relevant Bayesian Cram\\'er-Rao bounds.
Simulating synchronization in neuronal networks
NASA Astrophysics Data System (ADS)
Fink, Christian G.
2016-06-01
We discuss several techniques used in simulating neuronal networks by exploring how a network's connectivity structure affects its propensity for synchronous spiking. Network connectivity is generated using the Watts-Strogatz small-world algorithm, and two key measures of network structure are described. These measures quantify structural characteristics that influence collective neuronal spiking, which is simulated using the leaky integrate-and-fire model. Simulations show that adding a small number of random connections to an otherwise lattice-like connectivity structure leads to a dramatic increase in neuronal synchronization.
State observer for synchronous motors
Lang, Jeffrey H.
1994-03-22
A state observer driven by measurements of phase voltages and currents for estimating the angular orientation of a rotor of a synchronous motor such as a variable reluctance motor (VRM). Phase voltages and currents are detected and serve as inputs to a state observer. The state observer includes a mathematical model of the electromechanical operation of the synchronous motor. The characteristics of the state observer are selected so that the observer estimates converge to the actual rotor angular orientation and velocity, winding phase flux linkages or currents.
Optimized multiparty quantum clock synchronization
Ben-Av, Radel; Exman, Iaakov
2011-07-15
A multiparty protocol for distributed quantum clock synchronization has been claimed to provide universal limits on the clock accuracy, viz., that accuracy monotonically decreases with the number n of party members. But this is only true for synchronization when one limits oneself to W states. This work shows that the usage of Z (Symmetric Dicke) states, a generalization of W states, results in improved accuracy, having a maximum when Left-Floor n/2 Right-Floor of its members have their qubits with a |1> eigenstate.
Synchronization in an optomechanical cavity.
Shlomi, Keren; Yuvaraj, D; Baskin, Ilya; Suchoi, Oren; Winik, Roni; Buks, Eyal
2015-03-01
We study self-excited oscillations (SEO) in an on-fiber optomechanical cavity. Synchronization is observed when the optical power that is injected into the cavity is periodically modulated. A theoretical analysis based on the Fokker-Planck equation evaluates the expected phase space distribution (PSD) of the self-oscillating mechanical resonator. A tomography technique is employed for extracting PSD from the measured reflected optical power. Time-resolved state tomography measurements are performed to study phase diffusion and phase locking of the SEO. The detuning region inside which synchronization occurs is experimentally determined and the results are compared with the theoretical prediction. PMID:25871175
Synchronization with sound propagation delays
NASA Astrophysics Data System (ADS)
Haché, A.
2010-04-01
Complex systems that synchronize with acoustic signals, like chanting crowds and musical ensembles, have the intrinsic ability to maintain synchrony without external aid or visual cues, even when spread over wide areas. According to two models, the counterintuitive self-synchronization happens when the system's components have a spatial distribution that is sufficiently uniform. The roles of system size and density are examined for arrangements in 1, 2 and 3 dimensions. Asynchrony is predicted to become vanishingly small at high densities, and results suggest ways on how to minimize asynchrony in real-world situations.
Non-fragile H∞ synchronization of memristor-based neural networks using passivity theory.
Mathiyalagan, K; Anbuvithya, R; Sakthivel, R; Park, Ju H; Prakash, P
2016-02-01
In this paper, we formulate and investigate the mixed H∞ and passivity based synchronization criteria for memristor-based recurrent neural networks with time-varying delays. Some sufficient conditions are obtained to guarantee the synchronization of the considered neural network based on the master-slave concept, differential inclusions theory and Lyapunov-Krasovskii stability theory. Also, the memristive neural network is considered with two different types of memductance functions and two types of gain variations. The results for non-fragile observer-based synchronization are derived in terms of linear matrix inequalities (LMIs). Finally, the effectiveness of the proposed criterion is demonstrated through numerical examples. PMID:26655373
Chaos Synchronization of Two Coupled Dynamos Systems with Unknown System Parameters
NASA Astrophysics Data System (ADS)
Agiza, H. N.
This paper addresses the synchronization problem of two coupled dynamos systems in the presence of unknown system parameters. Based on Lyapunov stability theory, an active control law is derived and activated to achieve the state synchronization of two identical coupled dynamos systems. By using Gerschgorin theorem, a simple generic criterion is derived for global synchronization of two coupled dynamos systems with a unidirectional linear error feedback coupling. This simple criterion is applicable to a large class of chaotic systems, where only a few algebraic inequalities are involved. Numerical simulations results are used to demonstrate the effectiveness of the proposed control methods.
Classification and Evaluation of Coherent Synchronous Sampled-Data Telemetry Systems
NASA Technical Reports Server (NTRS)
Viterbi, Andrew
1961-01-01
This paper analyzes the various types of continuous wave and pulse modulation for the transmission of sampled data over channels perturbed by white gaussian noise. Optimal coherent synchronous detection schemes for all the different modulation methods are shown to belong to one of two general classes: linear synchronous detection and correlation detection. The figures of merit, mean-square signal-to-error ratio and bandwidth occupancy, are determined for each system and compared.
ERIC Educational Resources Information Center
Walkiewicz, T. A.; Newby, N. D., Jr.
1972-01-01
A discussion of linear collisions between two or three objects is related to a junior-level course in analytical mechanics. The theoretical discussion uses a geometrical approach that treats elastic and inelastic collisions from a unified point of view. Experiments with a linear air track are described. (Author/TS)
Fermi Timing and Synchronization System
Wilcox, R.; Staples, J.; Doolittle, L.; Byrd, J.; Ratti, A.; Kaertner, F.X.; Kim, J.; Chen, J.; Ilday, F.O.; Ludwig, F.; Winter, A.; Ferianis, M.; Danailov, M.; D'Auria, G.
2006-07-19
The Fermi FEL will depend critically on precise timing of its RF, laser and diagnostic subsystems. The timing subsystem to coordinate these functions will need to reliably maintain sub-100fs synchronicity between distant points up to 300m apart in the Fermi facility. The technology to do this is not commercially available, and has not been experimentally demonstrated in a working facility. Therefore, new technology must be developed to meet these needs. Two approaches have been researched by different groups working with the Fermi staff. At MIT, a pulse transmission scheme has been developed for synchronization of RF and laser devices. And at LBL, a CW transmission scheme has been developed for RF and laser synchronization. These respective schemes have advantages and disadvantages that will become better understood in coming years. This document presents the work done by both teams, and suggests a possible system design which integrates them both. The integrated system design provides an example of how choices can be made between the different approaches without significantly changing the basic infrastructure of the system. Overall system issues common to any synchronization scheme are also discussed.
PCM synchronization by word stuffing
NASA Technical Reports Server (NTRS)
Butman, S.
1969-01-01
When a transmitted word, consisting of a number of pulses, is detected and removed from the data stream, the space left by the removal is eliminated by a memory buffer. This eliminates the need for a clock synchronizer thereby removing instability problems.
Tweaking synchronization by connectivity modifications
NASA Astrophysics Data System (ADS)
Schultz, Paul; Peron, Thomas; Eroglu, Deniz; Stemler, Thomas; Ramírez Ávila, Gonzalo Marcelo; Rodrigues, Francisco A.; Kurths, Jürgen
2016-06-01
Natural and man-made networks often possess locally treelike substructures. Taking such tree networks as our starting point, we show how the addition of links changes the synchronization properties of the network. We focus on two different methods of link addition. The first method adds single links that create cycles of a well-defined length. Following a topological approach, we introduce cycles of varying length and analyze how this feature, as well as the position in the network, alters the synchronous behavior. We show that in particular short cycles can lead to a maximum change of the Laplacian's eigenvalue spectrum, dictating the synchronization properties of such networks. The second method connects a certain proportion of the initially unconnected nodes. We simulate dynamical systems on these network topologies, with the nodes' local dynamics being either discrete or continuous. Here our main result is that a certain number of additional links, with the relative position in the network being crucial, can be beneficial to ensure stable synchronization.
Synchronous Parallel Kinetic Monte Carlo
Mart?nez, E; Marian, J; Kalos, M H
2006-12-14
A novel parallel kinetic Monte Carlo (kMC) algorithm formulated on the basis of perfect time synchronicity is presented. The algorithm provides an exact generalization of any standard serial kMC model and is trivially implemented in parallel architectures. We demonstrate the mathematical validity and parallel performance of the method by solving several well-understood problems in diffusion.
Synchronization by elastic neuronal latencies
NASA Astrophysics Data System (ADS)
Vardi, Roni; Timor, Reut; Marom, Shimon; Abeles, Moshe; Kanter, Ido
2013-01-01
Psychological and physiological considerations entail that formation and functionality of neuronal cell assemblies depend upon synchronized repeated activation such as zero-lag synchronization. Several mechanisms for the emergence of this phenomenon have been suggested, including the global network quantity, the greatest common divisor of neuronal circuit delay loops. However, they require strict biological prerequisites such as precisely matched delays and connectivity, and synchronization is represented as a stationary mode of activity instead of a transient phenomenon. Here we show that the unavoidable increase in neuronal response latency to ongoing stimulation serves as a nonuniform gradual stretching of neuronal circuit delay loops. This apparent nuisance is revealed to be an essential mechanism in various types of neuronal time controllers, where synchronization emerges as a transient phenomenon and without predefined precisely matched synaptic delays. These findings are described in an experimental procedure where conditioned stimulations were enforced on a circuit of neurons embedded within a large-scale network of cortical cells in vitro, and are corroborated and extended by simulations of circuits composed of Hodgkin-Huxley neurons with time-dependent latencies. These findings announce a cortical time scale for time controllers based on tens of microseconds stretching of neuronal circuit delay loops per spike. They call for a reexamination of the role of the temporal periodic mode in brain functionality using advanced in vitro and in vivo experiments.
Sports Medicine Meets Synchronized Swimming.
ERIC Educational Resources Information Center
Wenz, Betty J.; And Others
This collection of articles contains information about synchronized swimming. Topics covered include general physiology and cardiovascular conditioning, flexibility exercises, body composition, strength training, nutrition, coach-athlete relationships, coping with competition stress and performance anxiety, and eye care. Chapters are included on…
Tweaking synchronization by connectivity modifications.
Schultz, Paul; Peron, Thomas; Eroglu, Deniz; Stemler, Thomas; Ramírez Ávila, Gonzalo Marcelo; Rodrigues, Francisco A; Kurths, Jürgen
2016-06-01
Natural and man-made networks often possess locally treelike substructures. Taking such tree networks as our starting point, we show how the addition of links changes the synchronization properties of the network. We focus on two different methods of link addition. The first method adds single links that create cycles of a well-defined length. Following a topological approach, we introduce cycles of varying length and analyze how this feature, as well as the position in the network, alters the synchronous behavior. We show that in particular short cycles can lead to a maximum change of the Laplacian's eigenvalue spectrum, dictating the synchronization properties of such networks. The second method connects a certain proportion of the initially unconnected nodes. We simulate dynamical systems on these network topologies, with the nodes' local dynamics being either discrete or continuous. Here our main result is that a certain number of additional links, with the relative position in the network being crucial, can be beneficial to ensure stable synchronization. PMID:27415259
Synchronous navigation for CT colonography
NASA Astrophysics Data System (ADS)
Huang, Adam; Summers, Ronald M.; Roy, Dave
2006-03-01
We present a synchronous navigation module for CT colonography (CTC) reading. The need for such a system arises because most CTC protocols require a patient to be scanned in both supine and prone positions to increase sensitivity in detecting colonic polyps. However, existing clinical practices are limited to reading one scan at a time. Such limitation is due to the fact that building a reference system between scans for the highly flexible colon is a nontrivial task. The conventional centerline approach, generating only the longitudinal distance along the colon, falls short in providing the necessary orientation information to synchronize the virtual navigation cameras in both scanned positions. In this paper we describe a synchronous navigation system by using the teniae coli as anatomical references. Teniae coli are three parallel bands of longitudinal smooth muscle on the surface of the colon. They are morphologically distinguishable and form a piecewise triple helix structure from the appendix to the sigmoid colon. Because of these characteristics, they are ideal references to synchronize virtual cameras in both scanned positions. Our new navigation system consists of two side-by-side virtual colonoscopic view panels (for the supine and prone data sets respectively) and one single camera control unit (which controls both the supine and prone virtual cameras). The capability to examine the same colonic region simultaneously in both scanned images can raise an observer's confidence in polyp identification and potentially improve the performance of CT colonography.
Speed control for synchronous motors
NASA Technical Reports Server (NTRS)
Packard, H.; Schott, J.
1981-01-01
Feedback circuit controls fluctuations in speed of synchronous ac motor. Voltage proportional to phase angle is developed by phase detector, rectified, amplified, compared to threshold, and reapplied positively or negatively to motor excitation circuit. Speed control reduces wow and flutter of audio turntables and tape recorders, and enhances hunting in gyroscope motors.
Sensorimotor Synchronization across the Life Span
ERIC Educational Resources Information Center
Drewing, Knut; Aschersleben, Gisa; Li, Shu-Chen
2006-01-01
The present study investigates the contribution of general processing resources as well as other more specific factors to the life-span development of sensorimotor synchronization and its component processes. Within a synchronization tapping paradigm, a group of 286 participants, 6 to 88 years of age, were asked to synchronize finger taps with…
High speed synchronizer card utilizing VLSI technology
NASA Technical Reports Server (NTRS)
Speciale, Nicholas; Wunderlich, Kristin
1988-01-01
A generic synchronizer card capable of providing standard NASA communication block telemetry frame synchronization and quality control was fabricated using VLSI technology. Four VLSI chip sets are utilized to shrink all the required functions into a single synchronizer card. The application of VLSI technology to telemetry systems resulted in an increase in performance and a decrease in cost and size.
Delay synchronization of temporal Boolean networks
NASA Astrophysics Data System (ADS)
Wei, Qiang; Xie, Cheng-jun; Liang, Yi; Niu, Yu-jun; Lin, Da
2016-01-01
This paper investigates the delay synchronization between two temporal Boolean networks base on semi-tensor product method, which improve complete synchronization. Necessary and sufficient conditions for delay synchronization are drawn base on algebraic expression of temporal Boolean networks. A example is presented to show the effectiveness of theoretical analysis.
Phase synchronization of neuronal noise in mouse hippocampal epileptiform dynamics.
Serletis, Demitre; Carlen, Peter L; Valiante, Taufik A; Bardakjian, Berj L
2013-02-01
Organized brain activity is the result of dynamical, segregated neuronal signals that may be used to investigate synchronization effects using sophisticated neuroengineering techniques. Phase synchrony analysis, in particular, has emerged as a promising methodology to study transient and frequency-specific coupling effects across multi-site signals. In this study, we investigated phase synchronization in intracellular recordings of interictal and ictal epileptiform events recorded from pairs of cells in the whole (intact) mouse hippocampus. In particular, we focused our analysis on the background noise-like activity (NLA), previously reported to exhibit complex neurodynamical properties. Our results show evidence for increased linear and nonlinear phase coupling in NLA across three frequency bands [theta (4-10 Hz), beta (12-30 Hz) and gamma (30-80 Hz)] in the ictal compared to interictal state dynamics. We also present qualitative and statistical evidence for increased phase synchronization in the theta, beta and gamma frequency bands from paired recordings of ictal NLA. Overall, our results validate the use of background NLA in the neurodynamical study of epileptiform transitions and suggest that what is considered "neuronal noise" is amenable to synchronization effects in the spatiotemporal domain. PMID:23273129
Chaos synchronization by resonance of multiple delay times
NASA Astrophysics Data System (ADS)
Martin, Manuel Jimenez; D'Huys, Otti; Lauerbach, Laura; Korutcheva, Elka; Kinzel, Wolfgang
2016-02-01
Chaos synchronization may arise in networks of nonlinear units with delayed couplings. We study complete and sublattice synchronization generated by resonance of two large time delays with a specific ratio. As it is known for single-delay networks, the number of synchronized sublattices is determined by the greatest common divisor (GCD) of the network loop lengths. We demonstrate analytically the GCD condition in networks of iterated Bernoulli maps with multiple delay times and complement our analytic results by numerical phase diagrams, providing parameter regions showing complete and sublattice synchronization by resonance for Tent and Bernoulli maps. We compare networks with the same GCD with single and multiple delays, and we investigate the sensitivity of the correlation to a detuning between the delays in a network of coupled Stuart-Landau oscillators. Moreover, the GCD condition also allows detection of time-delay resonances, leading to high correlations in nonsynchronizable networks. Specifically, GCD-induced resonances are observed both in a chaotic asymmetric network and in doubly connected rings of delay-coupled noisy linear oscillators.
Chaos synchronization by resonance of multiple delay times.
Martin, Manuel Jimenez; D'Huys, Otti; Lauerbach, Laura; Korutcheva, Elka; Kinzel, Wolfgang
2016-02-01
Chaos synchronization may arise in networks of nonlinear units with delayed couplings. We study complete and sublattice synchronization generated by resonance of two large time delays with a specific ratio. As it is known for single-delay networks, the number of synchronized sublattices is determined by the greatest common divisor (GCD) of the network loop lengths. We demonstrate analytically the GCD condition in networks of iterated Bernoulli maps with multiple delay times and complement our analytic results by numerical phase diagrams, providing parameter regions showing complete and sublattice synchronization by resonance for Tent and Bernoulli maps. We compare networks with the same GCD with single and multiple delays, and we investigate the sensitivity of the correlation to a detuning between the delays in a network of coupled Stuart-Landau oscillators. Moreover, the GCD condition also allows detection of time-delay resonances, leading to high correlations in nonsynchronizable networks. Specifically, GCD-induced resonances are observed both in a chaotic asymmetric network and in doubly connected rings of delay-coupled noisy linear oscillators. PMID:26986330
Christofilos, N.C.; Polk, I.J.
1959-02-17
Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.
Inhomogeneity induces relay synchronization in complex networks
NASA Astrophysics Data System (ADS)
Gambuzza, Lucia Valentina; Frasca, Mattia; Fortuna, Luigi; Boccaletti, Stefano
2016-04-01
Relay synchronization is a collective state, originally found in chains of interacting oscillators, in which uncoupled dynamical units synchronize through the action of mismatched inner nodes that relay the information but do not synchronize with them. It is demonstrated herein that relay synchronization is not limited to such simple motifs, rather it can emerge in larger and arbitrary network topologies. In particular, we show how this phenomenon can be observed in networks of chaotic systems in the presence of some mismatched units, the relay nodes, and how it is actually responsible for an enhancement of synchronization in the network.
Synchronization and Phase Dynamics of Oscillating Foils
NASA Astrophysics Data System (ADS)
Finkel, Cyndee L.
In this work, a two-dimensional model representing the vortices that animals produce, when they are ying/swimming, was constructed. A D{shaped cylinder and an oscillating airfoil were used to mimic these body{shed and wing{generated vortices, respectively. The parameters chosen are based on the Reynolds numbers similar to that which is observed in nature (˜10 4). In order to imitate the motion of ying/swimming, the entire system was suspended into a water channel from frictionless air{bearings. The position of the apparatus in the channel was regulated with a linear, closed loop PI controller. Thrust/drag forces were measured with strain gauges and particle image velocimetry (PIV) was used to examine the wake structure that develops. The Strouhal number of the oscillating airfoil was compared to the values observed in nature as the system transitions between the accelerated and steady states. The results suggest that self-regulation restricts the values of the Strouhal number to a certain range where no other external sensory input is necessary. As suggested by previous work, this self-regulation is a result of a limit cycle process that stems from nonlinear periodic oscillations. The limit cycles were used to examine the synchronous conditions due to the coupling of the foil and wake vortices. Noise is a factor that can mask details of the synchronization. In order to control its effect, we study the locking conditions using an analytic technique that only considers the phases. Our results show that the phase locking indices are dependent on the Strouhal value as it converges to a frequency locking ratio of ≃0:5. This indicates that synchronization occurs during cruising between the motion of the foil and the measured thrust/drag response of the uid forces. The results suggest that Strouhal number selection in steady forward natural swimming and ying is the result of a limit cycle process and not actively controlled by an organism. An implication of this is
Analysis of remote synchronization in complex networks
NASA Astrophysics Data System (ADS)
Gambuzza, Lucia Valentina; Cardillo, Alessio; Fiasconaro, Alessandro; Fortuna, Luigi; Gómez-Gardeñes, Jesus; Frasca, Mattia
2013-12-01
A novel regime of synchronization, called remote synchronization, where the peripheral nodes form a phase synchronized cluster not including the hub, was recently observed in star motifs [Bergner et al., Phys. Rev. E 85, 026208 (2012)]. We show the existence of a more general dynamical state of remote synchronization in arbitrary networks of coupled oscillators. This state is characterized by the synchronization of pairs of nodes that are not directly connected via a physical link or any sequence of synchronized nodes. This phenomenon is almost negligible in networks of phase oscillators as its underlying mechanism is the modulation of the amplitude of those intermediary nodes between the remotely synchronized units. Our findings thus show the ubiquity and robustness of these states and bridge the gap from their recent observation in simple toy graphs to complex networks.
Parallel integrated frame synchronizer chip
NASA Technical Reports Server (NTRS)
Ghuman, Parminder Singh (Inventor); Solomon, Jeffrey Michael (Inventor); Bennett, Toby Dennis (Inventor)
2000-01-01
A parallel integrated frame synchronizer which implements a sequential pipeline process wherein serial data in the form of telemetry data or weather satellite data enters the synchronizer by means of a front-end subsystem and passes to a parallel correlator subsystem or a weather satellite data processing subsystem. When in a CCSDS mode, data from the parallel correlator subsystem passes through a window subsystem, then to a data alignment subsystem and then to a bit transition density (BTD)/cyclical redundancy check (CRC) decoding subsystem. Data from the BTD/CRC decoding subsystem or data from the weather satellite data processing subsystem is then fed to an output subsystem where it is output from a data output port.
Synchronous Earth Observatory Satellite /SEOS/
NASA Technical Reports Server (NTRS)
Walter, L. S.
1974-01-01
NASA/GSFC is currently studying the applications and technical requirements for a Synchronous Earth Observations Satellite (SEOS). Such a satellite would combine the relatively high resolution and multi-spectral capability of the Earth Resources Technology Satellite (ERTS) with the on-station continuous monitoring of the Synchronous Meteorological Satellite (SMS). SEOS capability is geared to perform disaster warning of tornadoes and floods as well as to monitor transient phenomena affecting earth resources (e.g., green waves and algae blooms). The heart of the system is a Large Earth Survey Telescope (LEST) which has a designed 1.5 meter diameter. Spectral bands in the visible, near- and far-infrared have been selected to optimize SEOS utility. A microwave sounder will be used in conjunction with the LEST for meteorological applications.
Synchronization of electronic genetic networks.
Wagemakers, Alexandre; Buldú, Javier M; García-Ojalvo, Jordi; Sanjuán, Miguel A F
2006-03-01
We describe a simple analog electronic circuit that mimics the behavior of a well-known synthetic gene oscillator, the repressilator, which represents a set of three genes repressing one another. Synchronization of a population of such units is thoroughly studied, with the aim to compare the role of global coupling with that of global forcing on the population. Our results show that coupling is much more efficient than forcing in leading the gene population to synchronized oscillations. Furthermore, a modification of the proposed analog circuit leads to a simple electronic version of a genetic toggle switch, which is a simple network of two mutual repressor genes, where control by external forcing is also analyzed. PMID:16599758
Producing Newborn Synchronous Mammalian Cells
NASA Technical Reports Server (NTRS)
Gonda, Steve R.; Helmstetter, Charles E.; Thornton, Maureen
2008-01-01
A method and bioreactor for the continuous production of synchronous (same age) population of mammalian cells have been invented. The invention involves the attachment and growth of cells on an adhesive-coated porous membrane immersed in a perfused liquid culture medium in a microgravity analog bioreactor. When cells attach to the surface divide, newborn cells are released into the flowing culture medium. The released cells, consisting of a uniform population of synchronous cells are then collected from the effluent culture medium. This invention could be of interest to researchers investigating the effects of the geneotoxic effects of the space environment (microgravity, radiation, chemicals, gases) and to pharmaceutical and biotechnology companies involved in research on aging and cancer, and in new drug development and testing.
Synchronous clock stopper for microprocessor
NASA Technical Reports Server (NTRS)
Kitchin, David A. (Inventor)
1985-01-01
A synchronous clock stopper circuit for inhibiting clock pulses to a microprocessor in response to a stop request signal, and for reinstating the clock pulses in response to a start request signal thereby to conserve power consumption of the microprocessor when used in an environment of limited power. The stopping and starting of the microprocessor is synchronized, by a phase tracker, with the occurrences of a predetermined phase in the instruction cycle of the microprocessor in which the I/O data and address lines of the microprocessor are of high impedance so that a shared memory connected to the I/O lines may be accessed by other peripheral devices. The starting and stopping occur when the microprocessor initiates and completes, respectively, an instruction, as well as before and after transferring data with a memory. Also, the phase tracker transmits phase information signals over a bus to other peripheral devices which signals identify the current operational phase of the microprocessor.
Multiobjective synchronization of coupled systems
NASA Astrophysics Data System (ADS)
Tang, Yang; Wang, Zidong; Wong, W. K.; Kurths, Jürgen; Fang, Jian-an
2011-06-01
In this paper, multiobjective synchronization of chaotic systems is investigated by especially simultaneously minimizing optimization of control cost and convergence speed. The coupling form and coupling strength are optimized by an improved multiobjective evolutionary approach that includes a hybrid chromosome representation. The hybrid encoding scheme combines binary representation with real number representation. The constraints on the coupling form are also considered by converting the multiobjective synchronization into a multiobjective constraint problem. In addition, the performances of the adaptive learning method and non-dominated sorting genetic algorithm-II as well as the effectiveness and contributions of the proposed approach are analyzed and validated through the Rössler system in a chaotic or hyperchaotic regime and delayed chaotic neural networks.
Digital-data receiver synchronization
Smith, Stephen F.; Turner, Gary W.
2005-08-02
Digital-data receiver synchronization is provided with composite phase-frequency detectors, mutually cross-connected comparison feedback or both to provide robust reception of digital data signals. A single master clock can be used to provide frequency signals. Advantages can include fast lock-up time in moderately to severely noisy conditions, greater tolerance to noise and jitter when locked, and improved tolerance to clock asymmetries.
New Solutions for Synchronized Domineering
NASA Astrophysics Data System (ADS)
Bahri, Sahil; Kruskal, Clyde P.
Cincotti and Iida invented the game of Synchronized Domineering, and analyzed a few special cases. We develop a more general technique of analysis, and obtain results for many more special cases. We obtain complete results for board sizes 3 ×n, 5 ×n, 7 ×n, and 9 ×n (for n large enough) and partial results for board sizes 2×n, 4 ×n, and 6 ×n.
Proceedings of the international conference on maglev and linear drives
Not Available
1986-01-01
This book contains papers presented at a conference on Maglev and linear drives. Topics covered include: Development of superconducting magnets for the Canadian electrodynamic Maglev vehicle; Power supply system to drive HSST - Expo '86; and Thrust and levitation force characteristics of linear synchronous motors.
Network synchronization in hippocampal neurons.
Penn, Yaron; Segal, Menahem; Moses, Elisha
2016-03-22
Oscillatory activity is widespread in dynamic neuronal networks. The main paradigm for the origin of periodicity consists of specialized pacemaking elements that synchronize and drive the rest of the network; however, other models exist. Here, we studied the spontaneous emergence of synchronized periodic bursting in a network of cultured dissociated neurons from rat hippocampus and cortex. Surprisingly, about 60% of all active neurons were self-sustained oscillators when disconnected, each with its own natural frequency. The individual neuron's tendency to oscillate and the corresponding oscillation frequency are controlled by its excitability. The single neuron intrinsic oscillations were blocked by riluzole, and are thus dependent on persistent sodium leak currents. Upon a gradual retrieval of connectivity, the synchrony evolves: Loose synchrony appears already at weak connectivity, with the oscillators converging to one common oscillation frequency, yet shifted in phase across the population. Further strengthening of the connectivity causes a reduction in the mean phase shifts until zero-lag is achieved, manifested by synchronous periodic network bursts. Interestingly, the frequency of network bursting matches the average of the intrinsic frequencies. Overall, the network behaves like other universal systems, where order emerges spontaneously by entrainment of independent rhythmic units. Although simplified with respect to circuitry in the brain, our results attribute a basic functional role for intrinsic single neuron excitability mechanisms in driving the network's activity and dynamics, contributing to our understanding of developing neural circuits. PMID:26961000
Intonation contour in synchronous speech
NASA Astrophysics Data System (ADS)
Wang, Bei; Cummins, Fred
2003-10-01
Synchronous Speech (Syn-S), obtained by having pairs of speakers read a prepared text together, has been shown to result in interesting properties in the temporal domain, especially in the reduction of inter-speaker variability in supersegmental timing [F. Cummins, ARLO 3, 7-11 (2002)]. Here we investigate the effect of synchronization among speakers on the intonation contour, with a view to informing models of intonation. Six pairs of speakers (all females) read a short text (176 words) both synchronously and solo. Results show that (1) the pitch accent height above a declining baseline is reduced in Syn-S, compared with solo speech, while the pitch accent location is consistent across speakers in both conditions; (2) in contrast to previous findings on duration matching, there is an asymmetry between speakers, with one speaker exerting a stronger influence on the observed intonation contour than the other; (3) agreement on the boundaries of intonational phrases is greater in Syn-S and intonation contours are well matched from the first syllable of the phrase and throughout.
Synergistic effect of repulsive inhibition in synchronization of excitatory networks
NASA Astrophysics Data System (ADS)
Belykh, Igor; Reimbayev, Reimbay; Zhao, Kun
2015-06-01
We show that the addition of pairwise repulsive inhibition to excitatory networks of bursting neurons induces synchrony, in contrast to one's expectations. Through stability analysis, we reveal the mechanism underlying this purely synergistic phenomenon and demonstrate that it originates from the transition between different types of bursting, caused by excitatory-inhibitory synaptic coupling. This effect is generic and observed in different models of bursting neurons and fast synaptic interactions. We also find a universal scaling law for the synchronization stability condition for large networks in terms of the number of excitatory and inhibitory inputs each neuron receives, regardless of the network size and topology. This general law is in sharp contrast with linearly coupled networks with positive (attractive) and negative (repulsive) coupling where the placement and structure of negative connections heavily affect synchronization.
A statistical modeling approach for detecting generalized synchronization
Schumacher, Johannes; Haslinger, Robert; Pipa, Gordon
2012-01-01
Detecting nonlinear correlations between time series presents a hard problem for data analysis. We present a generative statistical modeling method for detecting nonlinear generalized synchronization. Truncated Volterra series are used to approximate functional interactions. The Volterra kernels are modeled as linear combinations of basis splines, whose coefficients are estimated via l1 and l2 regularized maximum likelihood regression. The regularization manages the high number of kernel coefficients and allows feature selection strategies yielding sparse models. The method's performance is evaluated on different coupled chaotic systems in various synchronization regimes and analytical results for detecting m:n phase synchrony are presented. Experimental applicability is demonstrated by detecting nonlinear interactions between neuronal local field potentials recorded in different parts of macaque visual cortex. PMID:23004851
Robustness to noise in synchronization of complex networks
Buscarino, Arturo; Gambuzza, Lucia Valentina; Porfiri, Maurizio; Fortuna, Luigi; Frasca, Mattia
2013-01-01
In this report, we investigate dynamical robustness of a complex network to noise injected through one of its nodes. We focus on synchronization of coupled nonlinear systems and, as a special instance, we address the classical consensus protocol for linear integrators. We establish an exact closed-form expression of the synchronization error for the consensus protocol and an approximate result for chaotic units. While structural robustness is known to be significantly affected by attacks targeted to network hubs, our results posit that dynamical robustness is controlled by both the topology of the network and the dynamics of the units. We provide examples where hubs perform better or worse than isolated nodes. PMID:23778265
Limitations and tradeoffs in synchronization of large-scale networks with uncertain links
NASA Astrophysics Data System (ADS)
Diwadkar, Amit; Vaidya, Umesh
2016-04-01
The synchronization of nonlinear systems connected over large-scale networks has gained popularity in a variety of applications, such as power grids, sensor networks, and biology. Stochastic uncertainty in the interconnections is a ubiquitous phenomenon observed in these physical and biological networks. We provide a size-independent network sufficient condition for the synchronization of scalar nonlinear systems with stochastic linear interactions over large-scale networks. This sufficient condition, expressed in terms of nonlinear dynamics, the Laplacian eigenvalues of the nominal interconnections, and the variance and location of the stochastic uncertainty, allows us to define a synchronization margin. We provide an analytical characterization of important trade-offs between the internal nonlinear dynamics, network topology, and uncertainty in synchronization. For nearest neighbour networks, the existence of an optimal number of neighbours with a maximum synchronization margin is demonstrated. An analytical formula for the optimal gain that produces the maximum synchronization margin allows us to compare the synchronization properties of various complex network topologies.
Limitations and tradeoffs in synchronization of large-scale networks with uncertain links
Diwadkar, Amit; Vaidya, Umesh
2016-01-01
The synchronization of nonlinear systems connected over large-scale networks has gained popularity in a variety of applications, such as power grids, sensor networks, and biology. Stochastic uncertainty in the interconnections is a ubiquitous phenomenon observed in these physical and biological networks. We provide a size-independent network sufficient condition for the synchronization of scalar nonlinear systems with stochastic linear interactions over large-scale networks. This sufficient condition, expressed in terms of nonlinear dynamics, the Laplacian eigenvalues of the nominal interconnections, and the variance and location of the stochastic uncertainty, allows us to define a synchronization margin. We provide an analytical characterization of important trade-offs between the internal nonlinear dynamics, network topology, and uncertainty in synchronization. For nearest neighbour networks, the existence of an optimal number of neighbours with a maximum synchronization margin is demonstrated. An analytical formula for the optimal gain that produces the maximum synchronization margin allows us to compare the synchronization properties of various complex network topologies. PMID:27067994
Limitations and tradeoffs in synchronization of large-scale networks with uncertain links.
Diwadkar, Amit; Vaidya, Umesh
2016-01-01
The synchronization of nonlinear systems connected over large-scale networks has gained popularity in a variety of applications, such as power grids, sensor networks, and biology. Stochastic uncertainty in the interconnections is a ubiquitous phenomenon observed in these physical and biological networks. We provide a size-independent network sufficient condition for the synchronization of scalar nonlinear systems with stochastic linear interactions over large-scale networks. This sufficient condition, expressed in terms of nonlinear dynamics, the Laplacian eigenvalues of the nominal interconnections, and the variance and location of the stochastic uncertainty, allows us to define a synchronization margin. We provide an analytical characterization of important trade-offs between the internal nonlinear dynamics, network topology, and uncertainty in synchronization. For nearest neighbour networks, the existence of an optimal number of neighbours with a maximum synchronization margin is demonstrated. An analytical formula for the optimal gain that produces the maximum synchronization margin allows us to compare the synchronization properties of various complex network topologies. PMID:27067994
Soliton synchronization in the focusing nonlinear Schrödinger equation
NASA Astrophysics Data System (ADS)
Sun, Yu-Hao
2016-05-01
The focusing nonlinear Schrödinger equation (NLSE) describes propagation of quasimonochromatic waves in weakly nonlinear media. The aim of this study is to determine conditions of soliton synchronization in the NLSE in terms of the solitons' position and phase parameters. For this purpose, the concept of asymptotic middle states of solitons in the NLSE is first introduced. With soliton solutions of the NLSE, it is shown that soliton synchronization can be achieved by synchronizing the asymptotic middle states of the solitons, and conditions of soliton synchronization in terms of the solitons' position and phase parameters are given. Although the interaction of the solitons is nonlinear, the conditions are linear equations. Then, aided with the synchronization conditions, simple initial conditions are presented for producing synchronized interaction of solitons without the need to obtain analytic expressions for the synchronized interaction of the solitons. The initial conditions are summations of fundamental solitons with no mutual overlap, so they might be convenient to implement in applicative contexts.
Cluster synchronization of complex networks via event-triggered strategy under stochastic sampling
NASA Astrophysics Data System (ADS)
Hu, Aihua; Cao, Jinde; Hu, Manfeng; Guo, Liuxiao
2015-09-01
This paper is concerned with the issue of mean square cluster synchronization of non-identical nodes connected by a directed network. Suppose that the nodes possess nonlinear dynamics and split into several clusters, then an event-triggered control scheme is proposed for synchronization based on the information from stochastic sampling. Meanwhile, an equilibrium is considered to be the synchronization state or the virtual leader for each cluster, which can apply pinning control to the following nodes. Assume that a spanning tree exists in the subgraph consisting of the nodes belonging to the same cluster and the corresponding virtual leader, and the instants for updating controllers are determined by the given event-triggered strategy, then some sufficient conditions for cluster synchronization are presented according to the Lyapunov stability theory and linear matrix inequality technique. Finally, a specific numerical example is shown to demonstrate the effectiveness of the theoretical results.
A chimeric path to neuronal synchronization
Essaki Arumugam, Easwara Moorthy; Spano, Mark L.
2015-01-15
Synchronization of neuronal activity is associated with neurological disorders such as epilepsy. This process of neuronal synchronization is not fully understood. To further our understanding, we have experimentally studied the progression of this synchronization from normal neuronal firing to full synchronization. We implemented nine FitzHugh-Nagumo neurons (a simplified Hodgkin-Huxley model) via discrete electronics. For different coupling parameters (synaptic strengths), the neurons in the ring were either unsynchronized or completely synchronized when locally coupled in a ring. When a single long-range connection (nonlocal coupling) was introduced, an intermediate state known as a chimera appeared. The results indicate that (1) epilepsy is likely not only a dynamical disease but also a topological disease, strongly tied to the connectivity of the underlying network of neurons, and (2) the synchronization process in epilepsy may not be an “all or none” phenomenon, but can pass through an intermediate stage (chimera)
A chimeric path to neuronal synchronization
NASA Astrophysics Data System (ADS)
Essaki Arumugam, Easwara Moorthy; Spano, Mark L.
2015-01-01
Synchronization of neuronal activity is associated with neurological disorders such as epilepsy. This process of neuronal synchronization is not fully understood. To further our understanding, we have experimentally studied the progression of this synchronization from normal neuronal firing to full synchronization. We implemented nine FitzHugh-Nagumo neurons (a simplified Hodgkin-Huxley model) via discrete electronics. For different coupling parameters (synaptic strengths), the neurons in the ring were either unsynchronized or completely synchronized when locally coupled in a ring. When a single long-range connection (nonlocal coupling) was introduced, an intermediate state known as a chimera appeared. The results indicate that (1) epilepsy is likely not only a dynamical disease but also a topological disease, strongly tied to the connectivity of the underlying network of neurons, and (2) the synchronization process in epilepsy may not be an "all or none" phenomenon, but can pass through an intermediate stage (chimera).
Compatibility of motion facilitates visuomotor synchronization.
Hove, Michael J; Spivey, Michael J; Krumhansl, Carol L
2010-12-01
Prior research indicates that synchronized tapping performance is very poor with flashing visual stimuli compared with auditory stimuli. Three finger-tapping experiments compared flashing visual metronomes with visual metronomes containing a spatial component, either compatible, incompatible, or orthogonal to the tapping action. In Experiment 1, synchronization success rates increased dramatically for spatiotemporal sequences of both geometric and biological forms over flashing sequences. In Experiment 2, synchronization performance was best when target sequences and movements were directionally compatible (i.e., simultaneously down), followed by orthogonal stimuli, and was poorest for incompatible moving stimuli and flashing stimuli. In Experiment 3, synchronization performance was best with auditory sequences, followed by compatible moving stimuli, and was worst for flashing and fading stimuli. Results indicate that visuomotor synchronization improves dramatically with compatible spatial information. However, an auditory advantage in sensorimotor synchronization persists. PMID:20695698
Explosive synchronization coexists with classical synchronization in the Kuramoto model.
Danziger, Michael M; Moskalenko, Olga I; Kurkin, Semen A; Zhang, Xiyun; Havlin, Shlomo; Boccaletti, Stefano
2016-06-01
Explosive synchronization has recently been reported in a system of adaptively coupled Kuramoto oscillators, without any conditions on the frequency or degree of the nodes. Here, we find that, in fact, the explosive phase coexists with the standard phase of the Kuramoto oscillators. We determine this by extending the mean-field theory of adaptively coupled oscillators with full coupling to the case with partial coupling of a fraction f. This analysis shows that a metastable region exists for all finite values of f > 0, and therefore explosive synchronization is expected for any perturbation of adaptively coupling added to the standard Kuramoto model. We verify this theory with GPU-accelerated simulations on very large networks (N ∼ 10(6)) and find that, in fact, an explosive transition with hysteresis is observed for all finite couplings. By demonstrating that explosive transitions coexist with standard transitions in the limit of f → 0, we show that this behavior is far more likely to occur naturally than was previously believed. PMID:27369869
Explosive synchronization coexists with classical synchronization in the Kuramoto model
NASA Astrophysics Data System (ADS)
Danziger, Michael M.; Moskalenko, Olga I.; Kurkin, Semen A.; Zhang, Xiyun; Havlin, Shlomo; Boccaletti, Stefano
2016-06-01
Explosive synchronization has recently been reported in a system of adaptively coupled Kuramoto oscillators, without any conditions on the frequency or degree of the nodes. Here, we find that, in fact, the explosive phase coexists with the standard phase of the Kuramoto oscillators. We determine this by extending the mean-field theory of adaptively coupled oscillators with full coupling to the case with partial coupling of a fraction f. This analysis shows that a metastable region exists for all finite values of f > 0, and therefore explosive synchronization is expected for any perturbation of adaptively coupling added to the standard Kuramoto model. We verify this theory with GPU-accelerated simulations on very large networks (N ˜ 106) and find that, in fact, an explosive transition with hysteresis is observed for all finite couplings. By demonstrating that explosive transitions coexist with standard transitions in the limit of f → 0, we show that this behavior is far more likely to occur naturally than was previously believed.
Synchronous Sampling for Distributed Experiments
NASA Astrophysics Data System (ADS)
Wittkamp, M.; Ettl, J.
2015-09-01
Sounding Rocket payloads, especially for atmospheric research, often consists of several independent sensors or experiments with different objectives. The data of these sensors can be combined in the post processing to improve the scientific results of the flight. One major requirement for this data-correlation is a common timeline for the measurements of the distributed experiments. Within this paper we present two ways to achieve absolute timing for asynchronously working experiments. The synchronization process is using the Global Positioning System (GPS) and a standard serial communication protocol for transport of timestamps and flight-states.
Nondestructive synchronous beam current monitor
Covo, Michel Kireeff
2014-12-15
A fast current transformer is mounted after the deflectors of the Berkeley 88-Inch Cyclotron. The measured signal is amplified and connected to the input of a lock-in amplifier. The lock-in amplifier performs a synchronous detection of the signal at the cyclotron second harmonic frequency. The magnitude of the signal detected is calibrated against a Faraday cup and corresponds to the beam intensity. It has exceptional resolution, long term stability, and can measure the beam current leaving the cyclotron as low as 1 nA.
Complexity and synchronization in stochastic chaotic systems
NASA Astrophysics Data System (ADS)
Son Dang, Thai; Palit, Sanjay Kumar; Mukherjee, Sayan; Hoang, Thang Manh; Banerjee, Santo
2016-02-01
We investigate the complexity of a hyperchaotic dynamical system perturbed by noise and various nonlinear speech and music signals. The complexity is measured by the weighted recurrence entropy of the hyperchaotic and stochastic systems. The synchronization phenomenon between two stochastic systems with complex coupling is also investigated. These criteria are tested on chaotic and perturbed systems by mean conditional recurrence and normalized synchronization error. Numerical results including surface plots, normalized synchronization errors, complexity variations etc show the effectiveness of the proposed analysis.