Synchronous Velocity Research Articles

Fuzzy Neural Network Compensator for Gantry Stage Synchronous Motion

In this paper, a fuzzy neural network (FNN) compensator is proposed for the synchronous motion control of a gantry position stage. Firstly, the cascade control strategy is applied to reduce the single axis position tracking error. However, the synchronous error between dual servo systems is inevitable due to their inequality in characteristics and the environmental uncertainties. The FNN compensator and an online learning algorithm perform a fuzzy reasoning with two inputs of synchronous position and velocity errors between dual drive servo systems and generate the compensated force; the compensated force is fed back to the controller of each axis. The online learning algorithm adjusts the connected weighting of the neural network by using a supervised gradient descent methods, such that the define error function can be minimized. Finally, two kinds of position commands with high and low frequency are designed for the experiments, and the experimental results show that the proposed FNN compensator is feasible to improve the synchronous error of gantry stage.

A General Alignment Repulsion Algorithm for Flocking of Multi-Agent Systems

A novel individual-based alignment/repulsion algorithm is proposed in this note for a flock of multiple agents. With this algorithm, each individual repels its sufficiently close neighbors and aligns to the average velocity of its neighbors with moderate distances. In both mathematical analysis and numerical simulation, we prove that the algorithm guarantees an uncrowded flocking behavior with asymptotic velocity synchronization when sufficiently intensive communication exists within the agents. Moreover, we provide the conditions for collision avoidance along the whole transient procedure. The proposed flocking model has its references in natural collective behaviors like escaping panic and traffic jam motions.

Bilateral Teleoperation Control Without Velocity Measurements

AbstractThis paper presents two controllers for a nonlinear bilateral teleoperation system that do not rely on velocity measurements. Under the reasonable assumptions that the human operator and the environment define passive maps from force to velocity, both controllers can ensure boundedness of velocities and position error. Moreover, if the human and environment forces are bounded, one of the controllers ensure velocity synchronization and the other velocity convergence to zero. Simulations, comparing the performance on free motion and interacting with a stiff wall, support the performance of the reported schemes.

Investigation of CO 2 laser beam modulation by rotating polygon

A beam-modulating system based on the rotating polygon has been proposed in a previous experimental work [14]. The aim was to improve the quality and efficiency of CO 2 laser surface texturing. Based on the generalized ABCD law, the focusing characteristics of a real beam through the modulating system are investigated in this paper. By introducing a precise defocusing, the velocity synchronization between the focal spot and the workpiece can be realized. Micro-dimples of nearly circular shape can be achieved on the surface. Surface texturing of mill roll has been performed. The experimental and theoretical results are in good agreement.

Fault Tolerant Attitude Synchronization Control during Formation Flying

It is necessary for precise satellite formations to keep each satellite in accurate relative attitude synchronization and to maintain relative angular velocity synchronization. An adaptive fuzzy terminal sliding mode control is proposed for a formation flying tracking system which includes acquisition, tracking, and pointing. The relative attitude of the leader and follower spacecraft under gravity gradient torque and external periodic disturbances is controlled by four reaction wheels. First, a terminal sliding mode controller is used to obtain stable and fast tracking. Then, the adaptive fuzzy logic system is used to approximate and learn the system uncertainty with the online fault and time-varied external disturbances. The system is proved to be stable, and the parameters are proved to be bounded under the control scheme, using a Lyapunov methodology. Finally, simulation results (under actuator faults like wheel failure and wheel degradation) show that the proposed control method has the advantages of...

Fractional order robust control for cogging effect compensation in PMSM position servo systems: Stability analysis and experiments

Fractional calculus is a generalization of the integration and differentiation to the fractional (non-integer) order. In this paper, for the first time, a fractional order robust control (FO-RC) method is devised for cogging effect compensation on permanent magnetic synchronous motors (PMSM) position and velocity servo system. In this FO-RC scheme, a fractional order robust controller is designed to compensate the cogging effect, and guarantee the boundedness of all signals. Stability properties have been proven for the systems with the traditional integer order robust control method and the proposed fractional order robust control scheme, respectively. Simulation illustration and experimental validation are presented to show the advantage of the proposed FO-RC scheme for cogging effect compensation over the conventional integer order method.

Improved Performance for the Synchronization of the Angular Velocity in Hybrid Electric Vehicles using a Feedforward Strategy

In this paper a multivariable control design task in the field of parallel hybrid electric vehicles is discussed. The control design covers the speed synchronization of two propulsion aggregates using a controllable separation clutch. During the synchronization period the longitudinal vehicle motion of the vehicle should not be affected. The proposed control strategy is based on a feedforward controller and two decoupled feedback controllers. The performance and robustness properties of the closed-loop system are shown by nonlinear simulation results.

Absolute dimensions of solar-type eclipsing binaries

We present a detailed study of the G0V detached eclipsing binary EW Ori, based on new photometric and spectroscopic observations. Masses and radii that are precise to 0.9% and 0.5%, respectively, have been established for both components. The 1.12 Msun secondary component reveals weak Ca II H and K emission and is probably mildly active; no signs of activity are seen for the 1.17 Msun primary. We derive an [Fe/H] abundance of +0.05 +/- 0.09 and similar abundances for Si, Ca, Sc, Ti, Cr, and Ni. Yonsai-Yale and Granada solar-scaled evolutionary models for the observed metal abundance reproduce the components fairly well at an age of approx. 2 Gyr. Perfect agreement is, however, obtained at an age of 2.3 Gyr for a combination of a) a slight downwards adjustment of the envelope mixing length parameter for the secondary, as seen for other active solar-type stars, and b) a slightly lower helium content than prescribed by the Y-Z relations adopted for the standard model grids. The orbit is eccentric (e = 0.0758 +/- 0.0020), and apsidal motion with a 62% relativistic contribution has been detected. The apsidal motion period is U = 16300 +/- 3900 yr, and the inferred mean central density concentration coefficient, log(k_2) = -1.66 +/- 0.30, agrees marginally with model predictions. The measured rotational velocities, 9.0 +/- 0.7 (primary) and 8.8 +/- 0.6 (secondary) km/s, are in agreement with both the synchronous velocities and the theoretically predicted pseudo-synchronous velocities. Finally, the distance (175 +/- 7 pc), age, and center-of mass velocity (6 km/s) exclude suggested membership of the open cluster Collinder 70. EW Ori now belongs to the small group of solar-type eclipsing binaries with well-established astrophysical properties.

Currency Allocation of Public External Debt and Synchronization Indicators of Exchange Rate Volatility

This paper uses synchronization indicators of domestic and foreign fundamentals to choose suitable currency allocation of public external debt. The selection of explanatory variables for exchange rate volatility is motivated using a New Keynesian Policy model that predicts that not only traditional optimum currency area (OCA) variables, but also variables considered by the literature on currency preferences, such as money velocity, should be relevant for explaining exchange rate volatility. I find that measures of inflation synchronization, money velocity synchronization and interest rate synchronization are useful indicators for deciding on the currency denomination of public external debt.

Frequency-dependent behaviors of individual microscopic particles in an optically induced dielectrophoresis device.

An optoelectronic microdevice is set up to drive single microparticles and a maximum synchronous velocity (MS-velocity) spectrum method is proposed for quantifying the frequency-dependent behaviors of individual neutral microparticles from 40 kHz to 10 MHz. Dielectrophoretic behaviors of three types of microparticles are investigated under the optically induced nonuniform electric field. Different MS-velocity spectra for the three different particles are experimentally found. Numerical calculations for the MS-velocity spectra of polystyrene microparticles are performed. The spectrum of the MS-velocities for a specific particle is mainly determined by the particle inherent property and the electric characteristics of the device. Moreover the experimental and the numerical MS-velocity spectra are compared to be accordant. Based on the dielectrophoretic (DEP) behaviors of the particles under a nonuniform electric field, microparticles can be finely characterized or distinguished according to their distinct MS-velocity spectra.

Electric-field-induced resonant tunneling lifetime in semiconductor multibarrier systems

A study on the variation in resonant tunneling lifetime (RTL) with the applied electric field is presented for the GaAs/AlxGa1−xAs periodic multibarrier systems (MBSs). The variation shows a contrasting behavior of lifetime for quasiresonant states situated at the miniband edge and those for well inside the miniband. For fields larger than 500 kV/m, the RTL corresponding to the midband state increases with the increase in electric field, whereas it decreases with the increase in field for the states near the miniband edges. The existence of the characteristic field and the characteristic lifetime that represent the synchronization of carrier velocity associated with all the quasiresonant states is an interesting outcome of the present theoretical investigation in ballistic transport of carriers through a MBS. This synchronization results in the maximum average escape rate through the system. It has also been shown that the characteristic field corresponds to the formation of localized partial Wannier–Stark ladder states in the miniband.

Spectroscopic and photometric analysis of NSV 24512: an early-type eclipsing binary embedded in a dust cloud★

We present differential V-band photometric observations and the first radial velocities of NSV 24512, which is embedded in the Serpens star-forming region. This double-lined system has an eccentric orbit with an eccentricity of 0.193. The system is a member of visual double star ADS 11410AB with a separation of about 0.3 arcsec and an apparent visual magnitude difference of 0.125 mag; we find that the fainter component (component B) is responsible for the periodic light variation. Therefore, we subtracted the light contribution of component A from the total light. The V-band photometric data and radial velocities were then analysed simultaneously using the Wilson–Devinney program. From the blue-wavelength spectroscopic observations and radial velocities, we classify the primary and secondary components as B8V and B9V stars, respectively. The masses and radii of the component stars have been derived as 3.68 ± 0.05 and 3.36 ± 0.04 M⊙ and 3.21 ± 0.05 and 2.93 ± 0.05 R⊙, respectively. Comparison with theoretical evolutionary models indicates that both components are pre-main-sequence stars with an age of about 2.1 Myr. The projected rotational velocities of the components measured by us are much smaller than the synchronous rotational velocities. The high asynchronism is further evidence of the very young age of the system. Using the radiative properties of the stars, we have redetermined the distance to NSV 24512 as 247 ± 5 pc, which is in good agreement with, and more precise than, previous determinations. Adopting the same interstellar extinction and distance, we classify component A to be of spectral type B7, if it is a single star.

Principle and basic characteristics of linear synchronous motor with half‐wave rectified self excitation

AbstractThis paper presents the principle and basic characteristics of a novel linear synchronous motor based on “half‐wave rectified self excitation principle.” The field winding is short circuited through a diode and the armature winding consists of conventional three‐phase windings. If the amplitude of the balance three‐phase currents is modulated by an alternating wave with bias frequency, the produced magnetomotive force pulsates at the bias frequency and moves at the synchronous velocity. This pulsating magnetomotive force induces the electromotive force with a bias frequency in the field winding. The field excitation is obtained by rectifying the electromotive force with the diode in the field winding. In this paper, the authors design and build an experimental machine and confirm its basic characteristics. They also deduce the performance equations and investigate the thrust ripple reduction. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 82–90, 2008; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/eej.20684

The outflow from Hudson Strait and its contribution to the Labrador Current

This study describes the first year round observations of the outflow from Hudson Strait as obtained from a moored array deployed mid-strait from August 2004–2005, and from a high-resolution hydrographic section conducted in September 2005. The outflow has the structure of a buoyant boundary current spread across the sloping topography of its southern edge. The variability in the flow is dominated by the extreme semi-diurnal tides and by vigorous, mostly barotropic, fluctuations over several days. The fresh water export is seasonally concentrated between June and March with a peak in November–December, consistent with the seasonal riverine input and sea-ice melt. It is highly variable on weekly timescales because of synchronous salinity and velocity variations. The estimated volume and liquid fresh water transports during 2004–2005 are, respectively, of 1–1.2 Sv and 78–88 (28–29) mSv relative to a salinity of 34.8 (33). This implies that the Hudson Strait outflow accounts for approximately 15% of the volume and 50% of the fresh water transports of the Labrador Current. This larger than previously estimated contribution is partially due to the recycling, within the Hudson Bay System, of relatively fresh waters that flow into Hudson Strait, along its northern edge. It is speculated that the source of this inflow is the outflow from Davis Strait.

A spectroscopic study of the close eclipsing binary HS Herculis

Aims. New high-resolution spectroscopic observations of the eclipsing binary HS Herculis are presented. The main aims were to determine the stellar parameters of the two components, their evolutionary stage, and to search for spectroscopic evidence for a possible third body. Methods. Using the cross-correlation technique, we detect spectroscopically the faint secondary component of HS Herculis, and for the firts time measure its radial velocity. The primary and secondary radial velocity curves are analyzed simultaneously and the results of the orbital solution are combined with those derived from multiband light curve analysis to derive orbital and stellar parameters. Results. We find the masses to be M 1 = 4.49±0.16 and M 2 = 1.75±0.09 M ⊙ , the radii to be R 1 = 2.83±0.04 and R 2 = 1.61±0.02 R ⊙ , and the effective temperatures to be T 1 = 15 200 ± 750 K and T 2 = 7600 ± 400 K for the primary and secondary stars, respectively. We also derive projected rotational velocities of the components as υ 1 sin i = 81 ± 3 and υ 2 sin i = 24 ± 6. Conclusions. While a synchronous rotation for the primary star is indicated by the broadening of the spectral lines, the secondary component appears to rotate more slowly, nearly one half the synchronous rotation velocity. This discrepancy indicates that the less massive secondary component could have not yet attained tidal synchronization. Although the presence of a third body physically bound to the eclipsing pair has been suggested by many investigators, we find no sign of its presence in our CCD spectra. The evolutionary stage of the system's components is briefly discussed by comparing their physical parameters with those of theoretical models. We find that the two components are located near the zero-age main sequence, with an age of about 32 Myr.

Principle and Basic Characteristics of Linear Synchronous Motor with Half-Wave Rectified Self Excitation

This paper presents principle and basic characteristics of a novel linear synchronous motor based on “half-wave rectified self excitation principle”. The field winding is short circuited through a diode and the armature winding is conventional 3-pahase windings. If the amplitude of the balanced 3-phase currents is modulated by an alternating wave with bias frequency, the produced magnetomotive force pulsates at bias frequency and moves at synchronous velocity. This pulsating magnetomotive force induces the electromotive force with bias frequency in the field winding. The field excitation is obtained by rectifying the electromotive force with the diode of the field winding. In this paper, we design and build the experimental machine and confirm the basic characteristics. We also deduce the performance equations and investigate on the thrust ripple reduction.

Spectroscopy and Photometry of the Double-lined Binary HD 149420

We have used new spectroscopic and photometric observations of HD 149420 to obtain an improved orbital element solution and determine some basic properties of the system. This double-lined binary has an orbital period of 3.39430 days, a circular orbit, and a mass ratio of 0.52. The primary is somewhat evolved, with an A9 IV spectral type, while the secondary is estimated to be an F5: dwarf. The secondary may be synchronously rotating, but the primary is rotating substantially slower than its synchronous velocity. Our photometric observations confirm the light variability and period found by Hipparcos. We determine a photometric period of 1.698 days, essentially half the value of the orbital period, with a peak-to-peak amplitude of 0.028 mag in V. In addition to this ellipsoidal light variation, we also detect more rapid, low-amplitude variability with a period of 0.076082 days and a peak-to-peak V amplitude of 0.008 mag, as well as a possible second short 0.059256 day period with a peak-to-peak amplitude of only 0.005 mag. This indicates that the A9 IV primary in HD 149420 is a pulsating δ Scuti variable. Our binary model that best fits both the radial velocity and photometric observations indicates the possibility of extremely shallow grazing eclipses, a circumstance not unexpected given the large minimum masses from the orbital solution, the evolved nature of the primary, and the short orbital period.

Modulation and trapping of a test beam in a traveling wave tube

For wave-particle interaction studies, the paradigmatic 1D beam-plasma system can be advantageously replaced by a Traveling Wave Tube (TWT). We consider the case when the cold beam intensity is low enough to ensure that instabilities are ruled out. This allows to carefully study the interaction of a beam of essentially test electrons with a single wave propagating in the TWT. By recording the test beam energy distribution at the output of the tube, we report the experimental observation of the velocity modulation and synchronization of a non-resonant beam and of the beam trapping by a resonant wave.

Surface plasma wave interactions between semiconductor and electromagnetic space harmonics from microwave to THz range

Transport properties of drift plasma near the surface of a semiconductor under the influence of electromagnetic (EM) waves were investigated both theoretically and experimentally. First, a general expression for the ω- and k-dependent effective permittivity of the drift plasma was derived, using the fluid model. Then, interdigital admittance of the drift plasma was calculated using the Green's function approach for space harmonics. In both of the collision-dominant (CD) case for microwave region and the nearly collision free (NCF) case for THz region, negative conductance values were predicted for GaAs and InP, which became remarkably large in the NCF case. In order to confirm the existence of surface plasma wave interactions, experiments were carried out in the CD case at microwave frequencies by using GaAs and InP samples with interdigital metal electrodes. S-parameter measurements revealed marked change of admittance in both samples near velocity synchronization between carrier drift and fundamental EM wave of the interdigital structure. Net negative conductance was not obtained most probably due to shielding by interface state admittance.

Multilane simulations of traffic phases.

The optimal velocity model, as modified by the author, is used in simulations of traffic on a dual-lane highway and a single-lane highway with an on-ramp. The equilibrium solutions of the modified model cover a two-dimensional region of flow-density space beneath the fundamental-diagram curve, rather than just lying on the curve as in the original model. Thus it satisfies a requirement of the three-phase model of Kerner [Phys. Rev. Lett. 81, 3797 (2002)]. Synchronization of velocity across dual lanes due to frequent lane changes is observed in free flow. True synchronized flow, as determined by the region of density-flow space it occupies, is obtained in on-ramp simulations with typical driver reaction times. A gradual change to the formation of a jam is observed for increasing delay times.