Synchronous Mode Research Articles

Synchronous behaviors of three coupled liquid crystal elastomer-based spring oscillators under linear temperature fields.

Self-oscillating coupled systems possess the ability to actively absorb external environmental energy to sustain their motion. This quality endows them with autonomy and sustainability, making them have application value in the fields of synchronization and clustering, thereby furthering research and exploration in these domains. Building upon the foundation of thermal responsive liquid crystal elastomer-based (LCE-based) spring oscillators, a synchronous system comprising three LCE-based spring oscillators interconnected by springs is established. In this paper, the synchronization phenomenon is described, and the self-oscillation mechanism is revealed. The results indicate that by varying system parameters and initial conditions, three synchronization patterns emerge, namely, full synchronous mode, partial synchronous mode, and asynchronous mode. For strongly interacting systems, full synchronous mode always prevails, while for weak interactions, the adjustment of initial velocities in magnitude and direction yields the three synchronization patterns. Additionally, this study explores the impact of several system parameters, including LCE elasticity coefficient and spring elasticity coefficient, on the amplitude, frequency, and synchronous mode of the system. The findings in this paper can enhance our understanding of the synchronization behavior of multiple mutually coupled LCE-based spring oscillators, with promising applications in energy harvesting, soft robotics, signal monitoring, and various other fields.

Feedback control of collective dynamics in an oscillator population with time-dependent connectivity.

We present a numerical study of pulsatile feedback-based control of synchrony level in a highly-interconnected oscillatory network. We focus on a nontrivial case when the system is close to the synchronization transition point and exhibits collective rhythm with strong amplitude modulation. We pay special attention to technical but essential steps like causal real-time extraction of the signal of interest from a noisy measurement and estimation of instantaneous phase and amplitude. The feedback loop's parameters are tuned automatically to suppress synchrony. Though the study is motivated by neuroscience, the results are relevant to controlling oscillatory activity in ensembles of various natures and, thus, to the rapidly developing field of network physiology.

Adaptation rules inducing synchronization of heterogeneous Kuramoto oscillator network with triadic couplings.

A class of adaptation functions is found for which a synchronous mode with different number of phase clusters exists in a network of phase oscillators with triadic couplings. This mode is implemented in a fairly wide range of initial conditions and the maximum number of phase clusters is four. The joint influence of coupling strength and adaptation parameters on synchronization in the network has been studied. The desynchronization transition under variation of the adaptation parameter occurs abruptly and begins with the highest-frequency oscillator, spreading hierarchically to all other elements.

Explosive synchronization in a turbulent reactive flow system.

The occurrence of abrupt dynamical transitions in the macroscopic state of a system has received growing attention. We present experimental evidence for abrupt transition via explosive synchronization in a real-world complex system, namely, a turbulent reactive flow system. In contrast to the paradigmatic continuous transition to a synchronized state from an initially desynchronized state, the system exhibits a discontinuous synchronization transition with a hysteresis. We consider the fluctuating heat release rate from the turbulent flames at each spatial location as locally coupled oscillators that are coupled to the global acoustic field in the confined system. We analyze the synchronization between these two subsystems during the transition to a state of oscillatory instability and discover that explosive synchronization occurs at the onset of oscillatory instability. Further, we explore the underlying mechanism of interaction between the subsystems and construct a mathematical model of the same.

Dynamics of oscillator populations with disorder in the coupling phase shifts

We study populations of oscillators, all-to-all coupled by means of quenched disordered phase shifts. While there is no traditional synchronization transition with a nonvanishing Kuramoto order parameter, the system demonstrates a specific order as the coupling strength increases. This order is characterized by partial phase locking, which is put into evidence by the introduced novel correlation order parameter, which is shown to grow monotonically with the coupling strength, and via frequency entrainment by following concentration of the oscillators frequencies. Simulations with phase oscillators, Stuart–Landau oscillators, and chaotic Roessler oscillators demonstrate similar scaling of the correlation order parameter with the coupling and the system size and also similar behavior of the frequencies with maximal entrainment (at which the standard deviation of the frequencies is reduced by a factor close to four) at some finite coupling.

Predefined-time sliding mode control for synchronization of uncertain hyperchaotic system and application

The main goal of this paper is to investigate the predefined-time sliding mode control and synchronization of uncertain hyperchaotic systems and its application in secure communication. Firstly, a novel predefined-time sliding surface is designed. Then a predefined-time sliding mode controller is proposed for uncertain hyperchaotic systems, which can guarantee synchronization of the master-slave system within a predefined time in the presence of parameter uncertain and external disturbance. Specially, the settling time, as a part of control parameters, can be predefined as needed independent of initial conditions. Furthermore, the validity of the proposed approach is proved by Lyapunov stability theory. Finally, comparative tests and image encryption application are given to show advantages of the proposed method.

Effect of ignition pattern on combustion characteristics in a hydrogen Wankel rotary engine: A numerical study

Hydrogen is considered the optimal solution for achieving high efficiency and low emissions in Wankel rotary engines (WREs). This paper aims to reveal the effect of ignition patterns on the combustion process of a hydrogen-fueled WRE. The results show that the combustion rate of the trailing spark plug (TSP), due to its structural similarity with the passive precombustion chamber, surpasses that of the leading spark plug (LSP). The unidirectional flow field promotes the forward development of the flame of TSP but inhibits the backward development of the flame of LSP. Moreover, the recess in combustion chamber facilitates flame propagation of TSP. Asynchronous ignition mode exhibits a higher indicated thermal efficiency (ITE) than synchronous ignition mode, facilitating effective control of the combustion phase. When the ignition timing of LSP is delayed, and TSP is earlier, the flame of TSP exceeds LSP, resulting in unchanged ITE. When the ignition timing of TSP is delayed, and LSP is earlier, the peak of free radicals and burned volume rate are the highest, resulting in a faster combustion rate. It is recommended that the LSP ignition timing is set earlier for practical operations.

Synchronization and firing mode transition of two neurons in a bilateral auditory system driven by a high–low frequency signal

The FitzHugh–Nagumo neuron circuit integrates a piezoelectric ceramic to form a piezoelectric sensing neuron, which can capture external sound signals and simulate the auditory neuron system. Two piezoelectric sensing neurons are coupled by a parallel circuit consisting of a Josephson junction and a linear resistor, and a binaural auditory system is established. Considering the non-singleness of external sound sources, the high–low frequency signal is used as the input signal to study the firing mode transition and synchronization of this system. It is found that the angular frequency of the high–low frequency signal is a key factor in determining whether the dynamic behaviors of two coupled neurons are synchronous. When they are in synchronization at a specific angular frequency, the changes in physical parameters of the input signal and the coupling strength between them will not destroy their synchronization. In addition, the firing mode of two coupled auditory neurons in synchronization is affected by the characteristic parameters of the high–low frequency signal rather than the coupling strength. The asynchronous dynamic behavior and variations in firing modes will harm the auditory system. These findings could help determine the causes of hearing loss and devise functional assistive devices for patients.

Toward Redefining Library Research Support Services in Australia and Aotearoa New Zealand: An Evidence-Based Practice Approach

An increasingly complex and demanding research landscape has seen university libraries rapidly evolve their services. While research data management, bibliometrics, and research impact services have predominantly featured in the literature to date, the full scope of support libraries are currently providing to their institutions is unknown. This paper aims to present an up-to-date view of the scope and extent of research support services by university libraries across Australia and Aotearoa New Zealand. A coding process analyzed content data from university library websites. Eleven research support areas were identified. Service delivery is split between synchronous and asynchronous modes. This paper describes a lived experience of an evidence-based library and information practice approach to improving research support services at two Australian university libraries, and while it highlights continued maturation of research support services, more research is needed to better understand influences on service development.

Multistability of synchronous modes in a multimachine power grid with a common load and their global and non-local stability

The purpose of this work is studying the dynamics of the power grid consisting of an arbitrary number of synchronous generators supplying a common passive linear load. We focus on searching the conditions for the existence and stability of synchronous modes, i.e. the main operating modes of a power grid. The possibility of the existence of non-synchronous (quasi-synchronous and asynchronous) modes is investigated. Methods. To study the dynamics of a power grid we use the effective network model in the form of an ensemble of globally coupled nodes-generators. The state of every node is described by the swing equation. The approach for reducing the effective network to the network with a hub topology (star topology) is proposed. We use numerical methods to construct a partition of the parameter space into areas with different operating modes of the power grid. Results. The conditions for the existence, stability and multistability of synchronous modes are obtained. The main characteristics of these modes are considered, such as the power supplied by generators to the grid and the distribution of currents along transmission lines. We constructed the partition of the power gird parameter space into areas with different dynamics. Conclusion. The power grid consisting of an arbitrary number of synchronous generators supplying a common passive linear load has been studied. We shown the presence of two types of synchronous modes: homogeneous and inhomogeneous. The first is characterized by equal powers and currents flowing through all load supply paths except one. The second provides another additional path, which differs from the others in current and transmitted power. Moreover, the currents flowing along the same path, but in various modes, differ. The presence of high multistability of inhomogeneous synchronous modes has been established. The possibility of coexistence of homogeneous and inhomogeneous synchronous modes, as well as quasi-synchronous and asynchronous modes, is shown. In the power grid parameters space we found areas corresponding both the existence of only synchronous modes and their coexistence with quasi-synchronous and/or asynchronous modes.

Особенности применения фильтра нижних частот для демодуляции информационных сигналов в электроприводе с фазовой синхронизацией

Phase-locking motor drive based on phase-lock principal provides high accuracy and wide shaft speed range. А low-pass filter is used for PWM-signal demodulation in phase-lock loop. This type of demodulator limits loop bandwidth and working range of motor drive. The main purpose of this article is to analyze low-pass filter influence on motor drive dynamic characteristics in low shaft speed area. The authors developed Matlab Simulink model to researcher phase-locking motor drive working in synchronous mode. As a result the dependence of angular velocity ripple versus rotational speed is obtained. The choosing condition of low-pass filter time constant is defined for different shaft speed area by using the obtained dependence. The received results can be applicable for design precision phaselock motor drive.

Development of a Digital Twin for the ABB IRB 1200 robot in sheet metal forming processes

This paper aims to detail the steps required to develop a digital twin based on a dynamic model of the ABB IRB 1200 7/0.7 robot (7kg payload, 0.7m maximum reach), using the Simulink platform. This model is needed in order to facilitate its use in robotic forming processes. The developed dynamic model allows a rigorous analysis of the resisting forces influencing the robot structure. ABB IRB 1200, being a small robot with a load capacity of only 7 kg, is ideal for complex simulations in Simulink, which can foresee various positioning configurations of the blank parts relative to the robot base to minimize the impact of the resistive forces.The use of the ABB IRB 1200 robot in roboforming processes is particularly relevant for the MIE department’s robotics lab from the Engineering Faculty of Sibiu, given the availability of two such units that can operate in synchronous mode. The synchronous implementation of two robots in roboforming processes has the potential to significantly improve the accuracy of manufactured components through the use of counter-punching. This method allows for tighter control of the forming process of metal parts, ensuring improved accuracy of finished products.

Collecting language assessment data in the age of pandemic: a preliminary case study of Chinese EFL learners

Abstract This study reports a preliminary exploration of the online collection of language assessment data in the author’s PhD project under the influence of the COVID-19 pandemic. It describes the challenges the author met, details the adaptations she made, and delineates its implications. Specifically, the data collection in this project involved remotely delivering three vocabulary tests and one speaking task to EFL learners in mainland China and collecting the results of these tests. In this process, the author trialed, pilot-tested, and compared three test-administering modes: first an asynchronous mode (Wenjuanwang), then a synchronous mode (Tencent Meeting), and finally a return to an asynchronous mode (Super Star Learning). It is hoped that this exploratory investigation into these technology-enhanced online methods will add a different perspective and present a multifaceted view for data collection of language assessment research during and after this pandemic.

Synchronous anti-phase variations between the East Asian summer monsoon and South America Summer Monsoon during Heinrich stadial 2

The interhemispheric anti-phase variation of monsoonal precipitation at the millennial timescale has been attributed to the latitudinal movement of the Intertropical Convergence Zone (ITCZ). However, a debate persists regarding the lead-lag or synchronous relationship between the Asian Summer Monsoon (ASM) and South American Summer Monsoon (SASM) on the onset and termination timings of the Heinrich stadials, hindering a deeper understanding of their underlying driving mechanisms. Here, we presented a new stalagmite δ18O record from Xianyun Cave, southeastern China. This record, with ∼5-year temporal resolution and an averaged uncertainty of ∼60 years on U–Th dates, spans Heinrich Stadial 2 (HS2) and represents East Asian Summer Monsoon (EASM) intensity variations. Based on our record, we further divided the evolution of the EASM during HS2 into three phases: an onset phase (HS2-I, 24,450–24,260 yr BP) and a termination phase (HS2-III, 23,950–23,630 yr BP), sandwiching a phase with relatively intensified monsoon (HS2-II, 24,260–23,950 yr BP). During the onset and termination of HS2, synchronous transition in monsoon records from both hemispheres was observed, driven by the large-scale meridional movement of the ITCZ. In HS2-I, a “Large excursion” observed in both tropical ISM and SASM records was also evidenced in the Xianyun record, suggesting an extension of the “Tropical atmospheric seesaw” to broader regions near tropical moisture sources. In phase II, our record precisely characterizes a centennial-scale strengthening of the EASM coinciding with a weakening SASM, while the Indian Summer Monsoon (ISM) showed no significant changes. The decoupling of the ISM and EASM may be related to the distinct responses of the regional ITCZ to El Niño-Southern Oscillation variabilities. Our study highlights the significant role of the tropical ocean-atmosphere coupling systems in the synchronized or divergent evolution of global monsoons within Heinrich stadials.

Team-Based Learning online: percepção dos graduandos de saúde e influência do perfil comportamental do estudante

Abstract Introduction: Team-Based Learning (TBL) is an active methodology that has shown to be effective for the training of health professionals. In 2020, due to the COVID-19 pandemic, TBL utilization migrated from the in-person to the synchronous online mode. Objectives: This study aimed to evaluate the perception of health undergraduate students about online TBL and to analyze whether there is a difference regarding this perception between groups of students with different levels of exposure prior to in-person and online sessions of the teaching method, in addition to verifying whether such perception can be affected by the student’s behavioral profile. Method: This is an observational, cross-sectional, descriptive-exploratory level II comparative study with a quantitative approach, carried out in undergraduate Nursing and Medicine courses between September and December 2021. A questionnaire on sociodemographic data was applied virtually, in addition to the Assessment of Student Perception-Team-Based Learning (ASP-TBL) and the DISC Personality Test instruments. Results: Of the 241 participating students, most were females (81%), aged between 20.8 and 24.4 years, who had already attended more than 10 sessions of in-person TBL (90%) and online TBL (53%). Of the 24 ASP-TBL questions, 17 obtained an index equal to or greater than 75% in the sum of the answers “I totally agree”/“I agree”, values considered as a positive perception in this study. Students exposed to more than 10 online TBL sessions had a significantly more negative perception in three of the four dimensions of the ASP-TBL, when compared to less exposed students. The group that had participated in more than 10 in-person TBL sessions had a significantly more negative perception in only one dimension of the instrument, when compared to the less exposed ones. The main DISC Personality test factor found among the participants’ behavioral profiles was submission (“S”). There was no correlation between the student’s behavioral profile and their perception of the method in the online version. Conclusions: There was a favorable perception of health undergraduate students regarding online TBL. Previous prolonged exposure to the method, both online and in-person, represented a significant difference in the students’ perception of online TBL. There was no evidence of the influence of the student’s behavioral profile on their perception of the teaching method.

Effect of Synchronous and Asynchronous Mode of Online Teaching on Achievement in Environmental Education of Prospective Teachers

Effect of Synchronous and Asynchronous Mode of Online Teaching on Achievement in Environmental Education of Prospective Teachers

Increasing the stability of the synchronization mode of the PLL system

Nowadays, the extremely rapid development of the global telecommunications network is accompanied by the search for new and the improvement of already existing radio- and other technologies, which are intended to further advance existing systems towards the construction of even more productive global transport networks, as well as networks of wireless broadband access, including 6G mobile communication networks and networks of subsequent generations. Among the important and widely used systems, it is worth highlighting the radio engineering system such as the Phase-Locked Loop (PLL) system, the capabilities for further improvement of which are far from exhausted. In particular, articles on various research issues and the use of the PLL systems for various applications are regularly published in world scientific and engineering publications. The use of PLL covers the issues of stabilizing the frequency of high-frequency generators, building high-precision frequency synthesizers and narrowband tracking filters, signal extraction against the background of noise in Doppler systems, demodulation of signals with frequency and phase modulation, the operation of magnetic recording playback devices, etc. This article analyzes the operating modes of the PLL system, in particular search, capture and hold, and it is found that when searching for the frequency of the reference generator, the system does not provide tuning of the frequency of the voltage-controlled generator as close as possible to this frequency. This, in turn, leads to the fact that after the frequency of the reference generator enters the capture range, the PLL system is instantly activated, which compensates for the current value of the frequency difference between the two generators, using part of the useful capability of the phase detector to process the frequency changes of both generators within the linear section of its discrimination characteristic. This situation is equivalent to not finding the frequencies of the reference and controlled generators, when their frequencies are equal, in the middle of the retention area, which negatively affects the stability of the PLL system as a whole. Based on the conducted analysis and the obtained conclusions, the paper proposes the principle of adjusting the PLL system as close as possible to the middle of the synchronization (holding) area, which ensures increased stability of the system against the influence of external factors, and also positively affects the reduction of the frequency noise level of this system. According to this principle of tuning, a corresponding block diagram of the PLL system was developed and an explanation of the operation of such a scheme was provided.

A 4D Entangled Memristor Hyperchaotic System and Its New Predefined-Time Sliding Mode Synchronization Control

A 4D Entangled Memristor Hyperchaotic System and Its New Predefined-Time Sliding Mode Synchronization Control

Analysis and simulation of X-band high-power microwave generation based on T-shaped four-period slow-wave structure

In this study, a T-shaped, four-period resonant slow-wave structure is optimally designed, and its high-frequency performance is comprehensively analyzed in theory. By using the image theory, the T-shaped waveguide unit is transformed into an equivalent ridge waveguide configuration. The high-frequency characteristics of the equivalent ridge waveguide, such as resonant frequency and structure of the T-shaped waveguide are analyzed by using equivalent circuit theory. The analysis has confirmed that in the ridge waveguide, starting from the second-highest order mode, the frequency points of the even-order modes are very consistent with those of the T-shaped waveguide; however, the odd-order modes have no such corresponding mode in the T-shaped waveguide, for they do not fulfill the electric boundary conditions required by the image method. On this basis, a T-shaped four-period resonant slow-wave structure is constructed, and its dispersion characteristics are analyzed to determine the resonant modes and frequencies, as well as the range of mode synchronization voltages. Simulations are subsequently performed to validate the effectiveness of the relativistic extended interaction radiation source, which includes the novel T-shaped periodic resonant slow-wave structure. Advanced three-dimensional particle simulations, in conjunction with optimization techniques show that a high-power microwave output at a frequency of 9.8 GHz, is achieved, which can delivers an average power of 71.4 MW. This output is attained under the conditions of a 448 kV beam voltage, 400 A beam current, and a 0.4 T uniform axial magnetic field, with an electron efficiency reaching 39.8%. This structure, characterized by the T-shaped waveguide, is demonstrated to be capable of producing high-efficiency, high-power microwaves with fewer periods, presenting a compact and efficient solution for generating high-power microwaves in advanced scientific applications.

Digital control of the synchronous modes of the two-rotor vibration set-up

The work is devoted to study of the effectiveness of the algorithm for controlling the synchronization of the rotors of a vibration unit (VU) with the digital implementation of the specified algorithm. A computer study of the dynamics of a two-rotor VU with a digital implementation of the control algorithm for rotor synchronization is carried out in the MATLAB environment. As a result the permissible sampling interval for calculating discrete control values using a zero-order extrapolator circuit was estimated. Also, using modeling, a comparative analysis of the efficiency of synchronization control in digital and analog implementation of the algorithm was carried out. It is shown that with an increase in the specified operating speed of the rotors, determined by the value of the energy H^∗ specified in the algorithm, the permissible value of the sampling interval decreases significantly. Comparison of the VU dynamics with the same values of the parameters of the synchronization control algorithm shows that the time of synchronization and the transient process in both cases are almost the same.