Synchronization Performance Research Articles

Study of Multi-motor Synchronous Operation Based on Sliding Mode Virtual Spindle Adjacent Cross-coupling Control

Aiming at the problems of uneven parameter differences and load torque distribution, which cause the tracking accuracy and synchronization performance of the multi-motor control system to be reduced, a multi-motor system control strategy with sliding mode virtual spindle adjacent cross-coupling control is proposed. First, the feedback torque of each motor is regulated by establishing a virtual spindle to improve the coordination of the system. Secondly, a speed compensator is designed to couple each motor to improve the system synchronization. Meanwhile, the sliding mode control strategy is used for the control of a single motor. The robustness and tracking accuracy of the system are tuned up. The simulation experiment results show that compared with the sliding mode cross-coupling control, sliding mode adjacent deviation coupling control, and PI virtual spindle-adjacent deviation coupling control, the system has a small synchronization error, strong anti-interference ability, and realizes high-precision coordinated control of multiple motors.

A Simulation Study of an Electro-Hydraulic Load-Sensitive Variable Pressure Margin Diverter Synchronous Drive System with Time-Varying Load Resistance

This study aims to address the problem of poor synchronous accuracy when facing a time-varying load in conventional load-sensitive synchronous drive systems. The new electro-hydraulic load-sensitive (EHLS) diverter synchronous drive system was proposed by combining the diverter valve and the EHLS synchronous drive system. The variable pressure margin compensation control was proposed to further improve the system’s synchronous control performance. Based on the system control strategy and component mathematical model, the simulation models of the EHLS, EHLS synchronous, and EHLS diverter synchronous drive systems were established using AMESim, respectively, and the synchronous control performance of the systems was obtained. The simulation results show that the EHLS drive system realized the primary functions of the load-sensitive system and could realize the variable load-sensitive pressure margin control. The EHLS synchronous drive system had poor synchronous control accuracy, but variable pressure compensation valve pressure margin control could be realized. The EHLS diverter synchronous drive system effectively improved the system’s synchronous control performance and diverter synchronous accuracy by variable pressure margin compensation control. The diverter system diverter error was reduced by 40.8%, and the diverter system after the compensation diverter error was reduced by 52.6% when the multi-way valves were fully opening. The system provides the solution for high-performance hydraulic synchronous drives under severe operating conditions.

Bidirectional Chaotic Synchronization Communication of Closed-Loop Mutually Coupled Nano-Lasers

It is well known that the dynamical characteristics of nano-lasers (NLs) have been extensively studied, but there is limited research on chaotic synchronization communication. In this paper, we propose a closed-loop system of mutually coupled NLs. Firstly, the autocorrelation function is employed to evaluate the capability of the system to conceal the time-delayed signature (TDS), and then, based on this, we specifically analyze the effects of the injection strength, frequency detuning, and parameter mismatch of two NLs on the chaotic synchronization performance, as well as the bidirectional communication. The detailed studies indicate that the proposed closed-loop mutually coupled system based on NLs can achieve high-quality chaotic synchronization with a low TDS and large bandwidth. In addition, the system maintains high-quality chaotic synchronization and communication performance even under significant parameter mismatch.

Auditory-motor synchronization and perception suggest partially distinct time scales in speech and music

Speech and music might involve specific cognitive rhythmic timing mechanisms related to differences in the dominant rhythmic structure. We investigate the influence of different motor effectors on rate-specific processing in both domains. A perception and a synchronization task involving syllable and piano tone sequences and motor effectors typically associated with speech (whispering) and music (finger-tapping) were tested at slow (~2 Hz) and fast rates (~4.5 Hz). Although synchronization performance was generally better at slow rates, the motor effectors exhibited specific rate preferences. Finger-tapping was advantaged compared to whispering at slow but not at faster rates, with synchronization being effector-dependent at slow, but highly correlated at faster rates. Perception of speech and music was better at different rates and predicted by a fast general and a slow finger-tapping synchronization component. Our data suggests partially independent rhythmic timing mechanisms for speech and music, possibly related to a differential recruitment of cortical motor circuitry.

Regulation of cluster synchronization in multilayer networks of delay coupled semiconductor lasers with the use of disjoint layer symmetry.

In real-world complex systems, heterogeneous components often interact in complex connection patterns and could be schematized by a formalism of multilayer network. In this work, the synchronization characteristics of multilayer network composed of semiconductor lasers (SLs) are investigated systematically. It is demonstrated that the interplay between different layers plays an important role on the synchronization patterns. We elucidate that the performance of cluster synchronization could be facilitated effectively with the introduction of disjoint layer symmetry into network topology. Intertwined stability of clusters from different layers could be decoupled into independent, and the parameter spaces for stable synchronization are extended significantly. The robustness of our proposed regulation scheme on operation parameters is numerically evaluated. Furthermore, the generality of presented theoretical results is validated in networks with more complex topology and multiple layers.

STUDY ON CHAOS CONTROL OF FRACTIONAL-ORDER UNIFIED CHAOTIC SYSTEM

This paper focuses on synchronization control of the fractional-order unified chaotic system. First, the stability of equilibria is analyzed by the Routh–Hurwitz criteria. Then, three different controllers are designed to achieve chaos synchronization of the drive-response unified system. Further, the impact of the fractional order on the synchronization performance is illustrated. Numerical simulations are carried out to verify the feasibility of theoretical analysis.

Stabilization and Synchronization of Neural Networks via Impulsive Adaptive Control.

This article addresses the stabilization and synchronization problems of coupled neural networks (NNs) via an impulsive adaptive control (IAC) strategy. Unlike the traditional fixed-gain-based impulsive methods, a novel discrete-time-based adaptive updating law for the impulsive gain is designed to maintain the stabilization and synchronization performance of the coupled NNs, where the adaptive generator only intermittently updates its data at the impulsive instants. Several stabilization and synchronization criteria for the coupled NNs are established based on the impulsive adaptive feedback protocols. Additionally, the corresponding convergence analysis are also provided. Finally, the effectiveness of the obtained theoretical results is illustrated using two comparison simulation examples.

Pinning Synchronization for Stochastic Complex Networks With Randomly Occurring Nonlinearities: Tackling Bit Rate Constraints and Allocations.

In this article, the ultimately bounded synchronization problem is investigated for a class of discrete-time stochastic complex networks under the pinning control strategy. Communication between system nodes and the remote controller is facilitated via wireless networks subject to bit rate constraints. The system model is distinguished by the inclusion of randomly occurring nonlinearities. A coding-decoding transmission mechanism under constrained bit rates is introduced to characterize the digital transmission process. To achieve synchronization of the network nodes with the unforced target node, a pinning controller is specifically devised based on the information from partially selected nodes. Through the application of the stochastic analysis method, a sufficient condition is derived for ensuring the mean-square boundedness of the synchronization error system. In addition, an optimization algorithm is introduced to address bit rate allocation and the design of desired controller gains. Within the presented theoretical framework, the correlation between the mean-square synchronization performance and bit rate allocation is further elucidated. To conclude, a simulation example is provided to substantiate the efficacy of the recommended pinning control approach.

Effects of individual practice on joint musical synchronization.

Successful music-making requires precise sensorimotor synchronization, both in individual (solo) and joint (ensemble) social settings. We investigated how individual practice synchronizing with a temporally regular melody (Solo conditions) influences subsequent synchronization between two partners (Joint conditions). Musically trained adults practiced producing a melody by tapping on a keypad; each tap generated the next tone in the melody. First, the pairs synchronized their melody productions with their partner in a baseline Joint synchronization task. Then each partner separately synchronized their melody with a computer-generated recording of the partner's melody in a Solo intervention condition that presented either Normal (temporally regular) auditory feedback or delayed feedback (by 30-70 ms) in occasional (25%) randomly placed tone positions. Then the pairs synchronized again with their partner in a Joint condition. Next, they performed the second Solo condition (normal or delayed auditory feedback) followed again by the Joint condition. Joint synchronization performance was modeled with a delay-coupled oscillator model to assess the coupling strength between partners. Absolute asynchronies in the Solo Intervention tasks were greater in the Delayed feedback condition than in the Normal feedback condition. Model estimates yielded larger coupling values between partners in Joint conditions that followed the Solo Normal feedback than the Solo Delayed feedback. Notably, the asynchronies were smaller in the Joint conditions than in the Solo conditions. These findings indicate that coupled interactions in settings of two or more performers can be improved by individual synchronization practice.

Novel insights into the co-metabolism of pyridine with different carbon substrates: Performance, metabolism pathway and microbial community

Pyridine is a widely employed nitrogen-containing heterocyclic organic, and the discharge of pyridine wastewater poses substantial environmental challenges due to its recalcitrance and toxicity. Co-metabolic degradation emerged as a promising solution. In this study, readily degradable glucose and the structurally analogous phenol were used as co-metabolic substrates respectively, and the corresponding mechanisms were thoroughly explored. To treat 400 mg/L pyridine, all reactors achieved remarkably high removal efficiencies, surpassing 98.5%. And the co-metabolism reactors had much better pyridine-N removal performance. Batch experiments revealed that glucose supplementation bolstered nitrogen assimilation, thereby promoting the breakdown of pyridine, and resulting in the highest pyridine removal rate and pyridine-N removal efficiency. The high abundance of Saccharibacteria (15.54%) and the enrichment of GLU and glnA substantiated this finding. On the contrary, phenol delayed pyridine oxidation, potentially due to its higher affinity for phenol hydroxylase. Nevertheless, phenol proved valuable as a carbon source for denitrification, augmenting the elimination of pyridine-N. This was underscored by the abundant Thauera (30.77%) and Parcubacteria (7.21%) and the enriched denitrification enzymes (narH, narG, norB, norC, and nosZ, etc.). This study demonstrated that co-metabolic degradation can bolster the simultaneous conversion of pyridine and pyridine-N, and shed light on the underling mechanism.

Clock synchronizing radio access networks to picosecond precision using optical clock distribution and clock phase caching

Performing positioning of future mobile devices using trilateration through radio access networks would provide a robust alternative to currently used global navigation satellite systems. However, the positioning accuracy is strongly dependent on the time synchronization accuracy of the antennas used as location reference points. Consequently, achieving sub-30 cm positioning accuracies requires the synchronization of radio access network antennas to sub-nanosecond accuracy. Here we show a clock phase synchronization and optical clock signal distribution approach to clock synchronization in radio access networks that achieves 0.98-ps root-mean-square precision clock synchronization, in a real-time field-trial demonstration on 37.6-km dark fiber, with optical clock frequency synchronization and clock phase caching operating using 25.6-Gb/s commercial transceivers. We quantify the clock synchronization performance of our approach using standard metrics, including time deviation (TDEV) and mean time interval error (MTIE). Furthermore, we estimate the impact of varying the phase update rate used in clock phase caching on the clock synchronization performance of our approach. Through our two combined approaches, we explore a route towards achieving sub-nanosecond clock synchronization in radio access networks.

Dynamical behaviors in discrete memristor-coupled small-world neuronal networks

The brain is a complex network system in which a large number of neurons are widely connected to each other and transmit signals to each other. The memory characteristic of memristors makes them suitable for simulating neuronal synapses with plasticity. In this paper, a memristor is used to simulate a synapse, a discrete small-world neuronal network is constructed based on Rulkov neurons and its dynamical behavior is explored. We explore the influence of system parameters on the dynamical behaviors of the discrete small-world network, and the system shows a variety of firing patterns such as spiking firing and triangular burst firing when the neuronal parameter α is changed. The results of a numerical simulation based on Matlab show that the network topology can affect the synchronous firing behavior of the neuronal network, and the higher the reconnection probability and number of the nearest neurons, the more significant the synchronization state of the neurons. In addition, by increasing the coupling strength of memristor synapses, synchronization performance is promoted. The results of this paper can boost research into complex neuronal networks coupled with memristor synapses and further promote the development of neuroscience.

Improved slot synchronization method for high-speed photon-counting communication based on SNSPD arrays

In optical communication systems based on photon-counting protocols, using highly efficient superconducting nanowire single-photon detectors (SNSPDs) is currently considered an effective solution for achieving high communication rates. However, in the process of increasing the communication channel throughput by reducing the slot width, as the slot frequency increases to the GHz level, the sub-nanosecond-level jitter caused by detection systems becomes non-negligible relative to the entire signal slot and greatly affects the accuracy of slot synchronization. To accurately characterize the photon arrival distribution of SNSPDs and further reduce communication error rates, we constructed a system. Through data analysis, we discovered that the photon arrival intensity distribution under the influence of jitter conforms to a non-homogeneous Poisson process (NHPP) and proposed a correction model for the photon arrival distribution and provided the corrected expression for the maximum likelihood estimation (MLE) algorithm. In subsequent experiments, combined with a blind search strategy, we enhanced the robustness of the model under different slot offset states and reduced the hardware complexity of existing synchronization schemes. The results show that at signal photons Ks=1.624 and background noise photons Kb=0.016 per symbol, the ideal Poisson model's hard decision error rate is 10.56 %, while the corrected model achieves an error rate close to the ideal synchronization performance at 8.9 %.

Improved autocorrelation method for time synchronization in filtered orthogonal frequency division multiplexing

Time synchronization is essential in multicarrier systems such as filtered orthogonal frequency division multiplexing (F-OFDM) because it determines the whole system’s performance. Differ with OFDM, where subcarrier allocation is not flexible. In F-OFDM, the subcarrier allocation is more flexible, and the whole subcarrier in one symbol can be grouped into several subbands. The use of subcarriers that are limited to only one subband can reduce the performance of time synchronization based on autocorrelation (AC) methods. In this study, we first compare the performance of the AC-based time synchronization algorithms used in F-OFDM when training symbols are limited to one subband. Secondly, we made improvements to the AC-based time synchronization with the averaging technique of its timing metric, thus increasing the accuracy of time estimates in the F-OFDM system. The averaging technique of the timing metric improved the performance of the AC method in cases where the training symbol is limited to one subband, as shown in the simulation results.

User Verification Using Evoked EEG by Invisible Visual Stimulation

Person authentication using biometric information has recently become popular among researchers. User management based on biometrics is more reliable than that using conventional methods. To secure private information, it is necessary to build continuous authentication-based user management systems. Brain waves are suitable biometric modalities for continuous authentication. This study is based on biometric authentication using brain waves evoked by invisible visual stimuli. Invisible visual stimulation is considered over visual stimulation to overcome the obstacles faced by a user when using a system. Invisible stimuli are confirmed by changing the intensity of the image and presenting high-speed stimulation. To ensure invisibility, stimuli of different intensities were tested, and the stimuli with an intensity of 5 % was confirmed to be invisible. To improve the verification performance, a continuous wavelet transform was introduced over the Fourier transform because it extracts both time and frequency information from the brain wave. The scalogram obtained by the wavelet transform was used as an individual feature and for synchronizing the template and test data. Furthermore, to improve the synchronization performance, the waveband was split based on the power distribution of the scalogram. A performance evaluation using 20 subjects showed an equal error rate of 3.8 %.

Simultaneously enhancing capacity and security in free-space optical chaotic communication utilizing orbital angular momentum

Optical chaotic signals emitted from an external-cavity feedback or injected laser diode enable small-signal information concealment in a noise-like carrier for secure optical communications. Due to the chaotic bandwidth limitation resulting from intrinsic relaxation oscillation frequency of lasers, multiplexing of optical chaotic signal, such as wavelength division multiplexing in fiber, is a typical candidate for high-capacity secure applications. However, to our best knowledge, the utilization of the spatial dimension of optical chaos for free-space secure communication has not yet been reported. Here, we experimentally demonstrate a free-space all-optical chaotic communication system that simultaneously enhances transmission capacity and security by orbital angular momentum (OAM) multiplexing. Optical chaotic signals with two different OAM modes totally carrying 20 Gbps on–off keying signals are secretly transmitted over a 2 m free-space link, where the channel crosstalk of OAM modes is less than −20 dB, with the mode spacing no less than 3. The receiver can extract valid information only when capturing approximately 92.5% of the OAM beam and correctly demodulating the corresponding mode. Bit error rate below the 7% hard-decision forward error correction threshold of 3.8×10−3 can be achieved for the intended recipient. Moreover, a simulated weak turbulence is introduced to comprehensively analyze the influence on the system performance, including channel crosstalk, chaotic synchronization, and transmission performance. Our work may inspire structured light application in optical chaos and pave a new way for developing future high-capacity free-space chaotic secure communication systems.

Time synchronization between satellites via inter-satellite link observations of BDS-3 Constellation: Method, experiment and analysis

Time synchronization through inter-satellite link (ISL) observations is crucial for enabling autonomous navigation in global navigation satellite systems. This study investigates the time synchronization performance within China's BeiDou Navigation Satellite System (BDS) using ISL measurements from 29 BDS-3 constellation satellites. A dedicated two-way time synchronization method is detailed, emphasizing its uniqueness and precision in ensuring accurate time synchronization. The study also delves into the application of various error corrections, encompassing time delay induced by motion, relativistic effects, and hardware delays. Ranging results show accuracies around 7 cm for one-way ISLs. The impact of error corrections is quantified, with the time delay error caused by motion exhibiting the most significant influence on synchronization accuracy. Using one month of BDS-3 ISL data, time synchronization accuracies better than 0.4 ns are consistently achieved between all satellites after implementing comprehensive error mitigation. The results indicate the robust performance of the BDS-3 ISL system for high-precision timekeeping, supporting autonomous orbit determination and navigation without relying on ground monitoring. These findings demonstrate the effectiveness of using ISLs for GNSS satellites and provide valuable insights for advancing satellite navigation capabilities.

Adaptive nonlinear second-order sliding mode synchronization control of direct drive H-type platform with zero error constraint

In order to achieve better synchronization performance for H-type platform servo systems during motion, an adaptive nonlinear second-order sliding mode synchronous control method with zero error constraint is proposed in this paper. The reason and mechanism of unsynchronized movement of H-type platform are analyzed. A synchronous thrust allocation algorithm based on dynamics is designed by using the thrust balance equation under zero error constraint to suppress the rotation movement of the crossbeam theoretically. To minimize the impact of external disturbances on the system, the system employs a robust adaptive nonlinear second-order sliding mode control method. In this method, the nonlinear sliding mode function is constructed to enhance the dynamic performance of the system, the second-order sliding mode surface is designed to achieve chatter-free control input. To address the issue of limitations in sliding mode control caused by upper limits of external disturbances, an adaptive control technique is employed to estimate and compensate for uncertainties such as external disturbances. Experimental results demonstrate that the proposed synchronous control strategy can effectively adjust the operating conditions of the two motors, improve the synchronous control performance and enhance the anti-interference ability of the system.

Bipartite secure synchronization for dynamic networks under deception attacks via delay-dependent impulsive control

In this paper, we investigate mean-square bounded bipartite synchronization of coupled dynamic networks subject to deception attacks, especially under directed/undirected signed interconnection structures. An impulsive secure control input involving stabilizing delays is proposed. The average impulsive delay (AID) method is used to fetch the information of time delay existing in impulses, and then this information is effectively integrated to mitigate the negative effects of deception attacks on synchronization. A concept of stochastic variables is introduced to serve as a measure of attack success when delayed impulsive control signals are replaced with false data from the impulsive controller-to-actuator. To achieve desired synchronization performance under deception attacks, the gains of pinning impulsive control, the average impulsive interval (AII), AID and the attack intensity are co-designed. An upper bound for synchronization errors is provided, which can be adjusted with multiple adjustable parameters. In addition, the AII and AID methods are used to remove the restriction on upper/lower bounds of two consecutive impulsive instants. Finally, numerical examples are given to illustrate the validity of the theoretical results.

Digital technologies in training the accompanist: practical dimension

Statement of the problem. The modern distance learning changes pedagogical strategies, methods, approaches, and the educational process. Institutions of art education, where training involves personal communication between the teacher and the student in the process of individual practical classes, found themselves in the most difficult situation. Therefore, it is important to understand the practical achievements of art universities in the field of distance learning as proven ways to overcome the remote “gap” between a teacher and a student. Recent research and publications. The problems of distance learning, taking into account the creative specificity, are investigated in the articles of the following Ukrainian scientists: Hubarieva et al., 2021; Lytvyn et al., 2021; Ponomarova et al., 2021; Davydov et al., 2022; Dedusenko et al., 2022; Ohrimenko et al., 2022; Prudnikova & Prudnikova, 2022; Tkachenko et al., 2022; Fabian et al., 2022. The works devoted to the formation of a pianist-accompanist are Molchanova, 2019, 2021, 2022; Nikitska & Savchenko, 2022. Objectives, methods and novelty of the research. The purpose of the study is to consider the positive and negative effects of distance education on the performing formation of a pianist-accompanist using digital technologies. A comprehensive approach is applied, combining the methods of analysis and generalization, systematization and projection, comparative, empirical, and experimental methods in accordance with the performance ensemble specifics. The scientific novelty consists in the study of practical developments in the distance learning of pianists of the Piano Accompaniment Department of Kharkiv I. P. Kotlyarevsky National University of Arts (Ukraine). Research results. The distance education in Ukraine has been complicated by the state of war, the departure of specialists abroad, funding restrictions and changes in educational policy. The formation of the accompanist is carried out by two strategies: together with the vocalist / instrumentalist and in the absence of soloists. All study participants face certain problems. For a pianist-apprentice, these are: loss of time on technological tasks, lack of sound display, unbalanced load. For soloists, these are: impossibility of synchronous performance, lack of emotional communication, singing or playing to the recorded accompaniment. For teachers, these are: the lack of direct contact with the ensemble members, the difficulty of correcting the sound, the obligatory verbalization of all remarks. Digital technologies that provide remote training of accompanist are as follows: 1. Google Meet and Zoom video conferences (“the teacher’s presence” effect); 2.MOODLE and GoogleClassroom platforms (organization of independent work and creation of online classes); 3. YouTube and Google Disk resources (access to video files with performance of compositions); 4. Messengers Viber, Telegram, ChatOn, WhatsApp, etc. (communication); 5. Editing applications – Adobe Acrobat Reader, Foxit Reader, Paint, Scissors, etc. (visualization of comments); 6. Applications for working with video recordings (for example, YouCut); 7. Ordinary telephone communication. General technical problems: instability of the Internet connection and its speed; obsolescence of gadget models; digital ignorance of distance learning participants, lack of a “common denominator” for evaluating the results of ensemble performance. Conclusion. The perspective of art education can be seen in finding hybrid forms of learning, combining synchronous and asynchronous models, taking into account the achievements of distance and face-to-face education and finding algorithms for building a combinatorial strategy.