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The problem of directional coupling detection in ensembles of temporally evolving systems from observed time series is important in diverse fields. A small ensemble of three oscillators is a model of large ensembles which carry important features such as the distinction between direct and indirect influences and, therefore, allows the study of the methods for coupling detection in respect of their ability to distinguish between such influences and, hence, correctly identify directional couplings and provide their appropriate quantitative description. This work considers an ensemble of three exemplary oscillators as a test system to improve the coupling estimation method based on phase dynamics modeling and compare it to the spectral approach called Granger – Geweke spectrum. Possibilities of false conclusions about the structure of couplings are analyzed, sensitivity of both methods and interpretations of coupling characteristics are discussed.

Asymptotic AFM amplitude-phase dynamics is a powerful modeling tool for the development of AFM control systems and applications. We explain the model and demonstrate simple practical examples that can be easily programmed and analyzed using simulation tools such as Control and Simulation Loop (National Instruments) or Simulink (Mathworks). We first introduce asymptotic AFM models, then formulate their mathematical properties relevant to AFM, and provide examples of simulation for Hertz and Lennard-Jones tip-sample interaction forces. Material of this paper can be used to study and practice AFM dynamics in simulation, as well as for design of AFM model-based control modes and applications.

A promising approach for efficiently solving NP-hard optimization problems is based on mapping the problems onto Ising machines. Oscillator-based Ising machines can be implemented by utilizing sub-harmonic injection locking, which enables binary phase shifts between the oscillators and leads to an improved reliability of Ising machines. Based on a modified Kuramoto model with sub-harmonic injection locking, we synthesize an ideal electrical circuit displaying the phase dynamics of an Ising machine. The ideal circuit can be utilized to specifically take non-ideal effects into account, serving as a starting point for designing Ising machines with increased performance when considering existing electrical components. We furthermore derive a corresponding wave digital model, which is utilized for emulating the synthesized electrical circuit. The emulation results show that the synthesized circuit indeed models the phase dynamics of an Ising machine capable of solving Max-Cut problems with an accuracy of 88% for a 5-node problem and weights between 0 and 31.

Cycle slips strongly impact the performance of phase tracking algorithm leading, in the worst case, to a permanent loss of lock of the signal. In this paper, we propose a new nonlinear phase estimator to obtain more robust tracks. The latter stems from a Variational Bayes (VB) approximation used within the optimal Bayesian filtering formulation in case of high-order phase dynamics. A comparison with a more conventional technique, namely a Kalman filter based PLL (Phase Lock Loop), is performed in terms of mean square error of the phase estimate and mean time to first slip. Results show that the proposed method outperforms the conventional linear filter with respect to both metrics, especially at low signal-to-noise ratio.

Bi-copter UAVs have emerged as more agile and energetically efficient flying platforms than quadrotor UAVs. Yet, they are more challenging to control due to the use of servo motors leading to non-minimum phase roll dynamics. In this paper, we systematically investigate the modeling, identification, and control of such non-minimum phase dynamics in an integrated way. We start with deriving the first principle model, from which the cause of the non-minimum phase is clearly seen. Parameters of the derived model are identified via experiments and subsequently used to design and analyze a high-gain robust flight controller via H ∞ loop shaping techniques. The designed controller is implemented on actual systems and compared against a well-tuned PID controller. Extensive flight tests are conducted to verify the controller’s effectiveness and the effect of the system’s non-minimum phase nature.

In this paper, we investigate the effectiveness of the method of coupling detection based on phase dynamics modeling in the analysis of the etalon systems whose phase dynamics properties are similar to the properties of the EEG signals from epilepsy patients who are in a coma state. On the example of the etalon model, a method of pre-filtering of signals is proposed, it provides a low level of errors while maintaining high sensitivity of the method. For the test systems, the optimal value of the method parameter and the length of the series are found.

This study aims to decrease the gap between invasive high-resolution data acquisition and non-invasive measurement in the animal model under auditory stimuli. We approach this problem by analyzing the degree of shared information between the phase of local field potentials (LFPs) of auditory cortices and the phase of auditory evoked responses (AER) at different frequency domains. It has been extensively illustrated in previous studies that the phase of evoked responses align reliably in presence of a repetitive stimulus. Yet this implies that changes in the instantaneous phase over a series of stimulus presentations must also be mirrored in the laminar activity. To estimate the impact of laminar specific activity on the AER dynamics over a series of acoustic stimulation, we employ an information theoretic approach (mutual information) for quantifying the relevant information encoded in the phase of laminar LFPs and AERs.

We apply retrospective cost adaptive control (RCAC) to a linearized aircraft dynamics with an unknown transition to nonminimum-phase (NMP) dynamics. In prior work, RCAC was used for command-following with unknown NMP zeros. In this work we extend those results to command following for cases where the dynamics transition from minimum-phase to NMP. We use system identification techniques to identify the NMP zero, and use this information in RCAC. We consider both full-state feedback and output feedback, and in both cases we follow step commands with transitioning dynamics. We first consider the case where RCAC is unaware of the change and NMP zero identification is unavailable to RCAC. We then assume that NMP zero information is available to RCAC from system identification.

Human walking is quite an efficient and smooth movement involving multiple successive phases. But for biped robots, most current dynamic walking models are simplified to some extent, with some phases neglected. This paper addresses the development of a complete multi-phase dynamics model for a biped robot. To achieve this, both the single support phase and double support phase are divided into two sub-phases by taking into consideration the rotation of stance foot around its toe and the rotation of swing foot around its heel. Therefore, a more human-like robotic gait is achieved, with transitions occurring at toe-off, heel-off, heel-strike, and toe-strike. Comparing the numbers of degrees of freedom with independent actuators of the biped robot, the whole gait cycle can also be represented by fully-actuated phase, under-actuated phase, and over-actuated phase. On this basis, the detailed dynamics model of each phase is derived using Euler-Lagrange method. And the validity of the dynamics model is demonstrated by simulation.

Plasma Focus devices are receiving attention in the field of plasma nanotechnology, particularly for the synthesis of nanostructured carbon and carbon thin films, since they are a good source of high energy ionic species. For attaining greater control over the deposition and processing of materials, the appropriate ion energies and ion flux and the control over plasma dynamics need to be achieved to make this process reliable and repeatable. One of the main parameter to achieve this control is the electrode dimensions, operating gas pressure, and gas mixture ratio in plasma focus device. We kept the operating voltages same. For example, to limit the amount of material deposited, it might be necessary to dilute the reactive gaseous environment with inert gases like He, N e or Ar. The dilution/mixture can affect the pinch dynamics inside the plasma focus device. In the present study, we report the use of different diagnostics, such as electrical probes and fast-gated imaging, to understand the pinch and post pinch plasma dynamics under methane gas operation mixed with neon and argon gases. In order to increase the pinch plasma volume for more material synthesis the experiments were also performed with modified plasma focus device with larger diameter anode. Elongated and larger volume pinch plasma column together with multiple pinches during later half-cycles of current discharge were obtained. These results will be discussed in detail during the conference.

We consider control of a dual rigid-body space-craft consisting of a bus and an appendage connected by a compliant joint. Thrust actuators are located on the spacecraft bus, and performance measurements are obtained from sensors on the appendage. This problem is challenging due to the flexibility of the joint and the noncolocation between the actuation and the performance variable. The goal is to motivate and investigate the challenges arising in control of nonminimum-phase (NMP) systems with rigid- and flexible-body dynamics. Exact equations of motion are derived for the spacecraft, and the invariant zeros of the linearized model are determined. This paper investigates the robustness of an adaptive control law to variations in the mass and inertia matrices of the bus and appendage as well as the geometry and joint stiffness. The adaptive controller uses no knowledge of the NMP dynamics.

This paper describes a fully distributed communication timing control method for wireless sensor networks, which exploits the properties of the emergent behavior of coupled phase oscillatory dynamics. Assuming the periodic data communications in massively distributed and locally interacting sensor nodes, a phase oscillatory dynamics is employed to realize a collision free communication timing control. For this purpose, we propose Phase Diffusion Synch- Alliance (PDSA) method, where coordination in repulsive and synchronous actions in the phase dynamics will take an essential role to self-organize a phase difference pattern corresponding to an efficient communication timing pattern in the distributed sensor nodes. We formulate the method and conduct simulations to verify effectiveness of PDSA.

The advent of high flux femtosecond electron sources provides a new window for observing atomic motions during structural transitions. Studies of ultrafast melting of metals reveal microscopic mechanisms and the full potential of the approach.

SUMMARY Since thr recent experimental observation of Dose-Einstein condensation in dilutc atomic gases, much interest has been raised about the coherence properties of the condensates Considerable attention has ben devoted to the matter uf the relativr phasp bctween two condensates: hm this phase manifests itself in an interference experiment [I], haw it cm be estnbliihed by measurement, and how it evolves in prespnee of atomic interactionsl2). Rerrritl) it was predicted that the relative phase betwm two condensates should display collopscs and revivals in time due to atomir inierxtioiis. For condcnsates with a rclatwely small number of atoms. of the ordcr of some hundreds, the revirds of thr 7ihar;e cm occur on the 10.'~ time Scale and niight in principle be observed. Howerer up to non a theoretical analysis of irifluence of partrcie lams 011 Lhr pha? dpnmirr B~F missing. Such loss proccs~s. due for example to collisions of rondmsed atonic With the buckgiuund gas or to three-bod! colliaionr. arp nnaruidiiblu in a real experiment and might spoil the cnherenrr prevmring the ubrurvtion of the revivals. IVe dewlop B model to dearrihe thP phase dynamici of the condensates m presence r the asaurnption that the fraction of lost parLicles in II, wc obtain analytical results for thP time depcrldcnce abservables for two nm overlapping and mutually non sueb as tlir nwm beating intensity of the condensates .epresented by the quantity (0'6) (a.herp o (a') and b (6') are the creation iannihilat,ion) operator^ of a particle in the condmsatr A ui B respectively). and the relacive phase probability distrihul ion. We find that. besides the collapses and revirals due to thr Hakiltonian evolution, the rrlvtive phase dependent observable (0'6) expericncps im esponmttal deea)- in time with a rate X given hr the mean total tiumber of luss ewnts per unit oft derohereuce betaren tw condensatcs, is therefore apprommatel inverse lifetiiiiu of a particle in the condensates (whew :T is the total number of atomr). Neverthclcs \ye show that losses do nnt prevent the ObsQrvatiOn of the rrlatise phase rsyivals in condensates with small number of atoms. Finally; se giw a suggestive interimtation of the dramatic cffect of the losses on the rflatii-e phase based on the h1oel.e Carlo wa\p function approach the condensates relative phase in a single !dome Carlo reaiization is shifted br a random amount on tbe order of 7 cosarquently to each mch loss event occurring in the condensates. A few loss prorcsses in a given time interd are then sufficient to smear out the relative phase completely when the average over the stochastic realizacion is taker

Focusing on the mechanisms underlying the appearance of phase multistability, the paper examines a variety of phase-locked patterns in the bursting behavior of a model of coupled pancreatic cells. In particular, we show how the number of spikes per train and the proximity of a neighboring equilibrium point can influence the formation of coexisting regimes.

In this paper we present experimental results of a multivariable linear predictive control strategy applied to a coupled, non-minimum phase dynamics system of six coupled water tanks with 3 controlled water levels (cm) and 3 manipulated pump outputs (V). The setup can be considered as three interacting sub-systems, with coupled dynamics due to the specific water flow directions. The experimental results indicate that the proposed strategy is robust to significant modelling errors, while maintaining good performance.

Adaptive control of a two-dimensional model of a flexible spacecraft with noncolocated sensors and actuators is achieved by output feedback using knowledge of only the system's impulse response. The model is composed of two planar rigid bodies linked by a torsional spring that emulates a multibody spacecraft with base body actuation and appendage pointing. Retrospective cost adaptive control is applied to a command-following problem. The controller uses a finite impulse response filter built from the Markov parameters of the nonminimum-phase (NMP) linearized model. Accordingly, this filter is constructed to contain an estimate of the location of the NMP zero; the filter's order is chosen to correspond to the number of time steps after which the plant's step response becomes positive.

This paper deals with output synchronization problem in nonlinear multi-agent systems. The main contribution of the paper is to guarantee output synchronization in the network while the dynamics of agents exhibit non-minimum phase behavior. To achieve this goal, a control signal is presented for each agent consisting of two terms. The first term is a linear function of each agent states employed in order to overcome the non-minimum phase dynamics of the multi-agent system, whereas the second term is a function of the output of neighboring agents which provides coupling among agents and guarantees output synchronization in the network. A numerical example is presented to verify the effectiveness of the proposed approach.

In this paper a new approach for studying slow transients, such as electromechanical transients, using three phase models of power systems is presented. Typically programs used for studying slow transients assume a positive sequence network model, limiting their application to the study of balanced power systems. While electromagnetic simulation software can be used for studying slow transients in unbalanced networks, their application to large systems can be resource and time intensive. The approach presented here overcomes the aforementioned limitations of existing software and provides a means for studying slow transients using complete three phase models of the electric network. Of the many potential applications of the approach presented, evaluating the impact of Distributed Generation (DG), such as rooftop solar photovoltaic (PV) based DG, on the stability of the electric grid is important particularly for utilities with high penetration of DG.

This paper investigates four control architectures that use adaptive control to follow step, ramp, and harmonic roll-angle commands for a linearized aircraft model with an unknown transition from minimum-phase to nonminimum-phase (NMP) dynamics. In particular, we consider retrospective cost adaptive control (RCAC) with 1) a command-feedforward control architecture; 2) an output-feedback control architecture; 3) a centralized control architecture that uses both command feedforward and output feedback; and 4) a decentralized control architecture that uses both command feedforward and output feedback. For baseline tests, we assume that the location of the NMP zero is known. The goal of this work is to improve the transient response and rate of convergence. Numerical testing shows that RCAC with the decentralized control architecture using command feedforward and output feedback gives the fastest convergence. Furthermore, resetting controller coefficients at the start of the transition improves the transient response.

Accounting for spectral hole burning (SHB), carrier heating (CH), carrier density modulation and longitudinal nonuniformity, ultrafast phase dynamics in bulk semiconductor optical amplifiers (SOAs) is numerically studied for different pump and probe wavelengths. We find that the contributions of SHB and CH to ultrafast phase dynamics are different in strength and change direction for different bands. Furthermore, we demonstrate that the phase dynamic range, phase recovery overshoot and phase partial recovery time depend on the probe and pump spectral positions.

Summary form only given. Nonlinear delay dynamical systems have found several fundamental and applied issues in Optics, since delays from time of flight of the light becomes easily important, even with a few cm of fibers, compared to fast or even ultra-fast photonic response times. Fiber pigtailed modern Telecom devices can thus provide easy system design strategies to build well-controlled high complexity nonlinear delay dynamics. Recently in that context, electro-optic phase modulation, combined with an imbalanced Mach-Zehnder DPSK demodulator providing a temporally nonlocal nonlinear phase-to-intensity conversion, together with a delayed optoelectronic feedback loop, was proposed as an efficient optical chaos generator for demonstrating 10 Gb/s optical chaos communications.

In this paper, a new lattice Boltzmann model, called the artificial interface lattice Boltzmann model (AILB model), is proposed for the simulation of two-phase dynamics. The model is based on the principle of free energy minimization and invokes the Gibbs-Duhem equation in the formulation of non-ideal forcing function. Bulk regions of the two phases are governed by a non-ideal equation of state (for example, the van der Waals equation of state), whereas an artificial near-critical equation of state is applied in the interfacial region. The interfacial equation of state is described by a double well density dependence of the free energy. The continuity of chemical potential is enforced at the interface boundaries. Using the AILB model, large density and viscosity ratios of the two phases can be simulated. The model is able to quantitatively capture the coexistence curve for the van der Waals equation of state for different temperatures. Moreover, spatially varying viscosities can be simulated by choosing the relaxation time as a function of local density.

Ultrafast spectroscopy of quantum dot semiconductor optical amplifiers (SOAs) provides valuable information about the potential of these devices for emerging applications such as multi-wavelength regeneration while giving insight on their unique carrier dynamics. Pump-probe spectroscopy was used to analyse the carrier dynamics in InAs/GaAs quantum dot amplifiers. We have developed a ldquotwo-colourrdquo experimental configuration that allows us to pump and probe different parts of the amplified spontaneous emission spectrum and develop a detailed picture of the relevant carrier processes in both absorption and gain regimes of QD-SOAs. The study has revealed that hole recovery and intradot electron relaxation occur on a picosecond timescale, while the electron capture time is on the order of 10 ps. The relaxation of the wetting layer carrier density was shown to have a strong effect on the phase dynamics of both ground and excited state transients, while having a much weaker effect on the gain dynamics. Such behaviour is strongly encouraging for reduced pattern effect operation in high speed optical networks.

Towards hardware implementation of real-time visual image processing, we propose a piecewise linear (PWL) approximation of a coupled region-based Markov Random Field (MRF) model with hidden phase variables for coarse image region segmentation. We introduce PWL functions into update equations of the region-based model, in order to make it easy to control parameters that determine the balance between image segmentation and smoothing, as well as to make it efficient for hardware implementation. We can tune filtering properties of our model by controlling the parameters of the PWL functions in applications to a task of coarse image region segmentation. Finally, we demonstrate that closed regions in input images can be represented by phase variables in multi-scale.