Synchronization Characteristics Research Articles

Evaluating the Effect of Increasing Working Memory Load on EEG-Based Functional Brain Networks

Purpose: Working Memory (WM) plays a crucial role in many cognitive functions of the human brain. Examining how the inter-regional connectivity and characteristics of functional brain networks modulate with increasing WM load could lead to a more in-depth understanding of the WM system.
 Materials and Methods: To investigate the effect of WM load alterations on the inter-regional synchronization and functional network characteristics, we used Electroencephalogram (EEG) data recorded from 21 healthy participants during an n-back task with three load levels (0-back, 2-back, and 3-back). The networks were constructed based on the weighted Phase Lag Index (wPLI) in the theta, alpha, beta, low-gamma, and high-gamma frequency bands. After constructing the fully connected, weighted, and undirected networks, the node-to-node connections, graph-theory metrics consisting of mean Clustering coefficient (C), characteristic path Length (L), and node strength were analyzed by statistical tests.
 Results: It was revealed that in the presence of WM load (2- and 3-back tasks) compared with the WM-free condition (0-back task) within the alpha range, the Inter-Regional Functional Connectivity (IRFC), functional integration, functional segregation, and node strength in channels located at the frontal, parietal and occipital regions were significantly reduced. In the high-gamma band, IRFC was significantly higher in the difficult task (3-back) compared to the easy and moderate tasks (0- and 2-back). Besides, locally clustered connections were significantly increased in 3-back relative to the 2-back task.
 Conclusion: Inter-regional alpha synchronization and alpha-band network metrics can distinguish between the WM and WM-free tasks. In contrast, phase synchronization of high-gamma oscillations can differentiate between the levels of WM load, which demonstrates the potential of the phase-based functional connectivity and brain network metrics for predicting the WM load level.

Study on energy and information storage properities of 2D-MXene/polyimide composites

The memristor is a basic unit of advanced information storage devices. As a passive device, it needs additional bias voltage to drive, which brings great challenges to the development of highly integrated of memristors. Therefore, it is urgent to develop highly reliable functional materials with both resistance memory and electric energy storage properties. Herein, with the introduction of Ti3C2TX nanosheets (TCTNs) into a polyimide matrix, we take the lead in realizing synchronous resistance memory characteristics and energy storage performance in one material system. With the addition of only 0.5 wt% TCTNs, the charge-discharge energy storage density of the polyimide (PI)-based composite increased by approximately 30%, and showed the memristor characteristics. More encouragingly, the composites also exhibited a massive increase in mechanical flexibility and electrical reliability. The slightly ordered arrangement of TCTNs in the PI matrix was confirmed by synchrotron radiation SAXS and HR-TEM. Finite element analysis was used to simulate the redistribution of the stress field and electric field of these composites in the presence of different distribution states of TCTNs. The chemical valence state and the atomic structure of TCTNs in the PI matrix were investigated by synchrotron radiation XAFS technology. DFT calculation models were established to calculate the evolution of the energy band structure of TCTNs during the synthesis process of the composites, determining the synergistic enhancement mechanism of energy storage and information storage properties in TCTNs/PI composites. This study is expected to provide a material candidate of highly integrated and reliable self-powered information storage devices.

Synchronization characteristics of two vibrators in a novel hydraulic coupling system

The machines that utilize the synchronization of vibrators, such as pile sinkers, breaking hammers and sonic drilling rigs, play an important role in municipal construction and resource exploration. In this paper, a novel hydraulic coupling system with large specific power, handy control and robust stability for vibrator synchronization is presented. To investigate the feasibility and precision of the synchronization of the vibrators in the system, a mathematical model is established. According to the model, the synchronization characteristics of two vibrators are discussed when the errors of their masses, eccentricities and viscous damping coefficients are considered. Furthermore, simulation analyses are performed to verify the numerical results. The results demonstrate that two vibrators can be synchronized by coupling the components. The precision of synchronization is attractive, although the precision at high speed is inferior to that at low speed. The precision of the synchronization is more dominated by eccentricity than the other two parameters.

Design and Analysis of Novel Synchronous Motion Technique for a Multi-Module Permanent Magnet Linear Synchronous Motor

Traditionally, synchronous motion among multi-module permanent magnet linear synchronous motors (PMLSM) has been achieved by adopting independent power supply and control. This method, however, requires multiple drivers and has control time delays. This paper proposes a novel approach to overcome these drawbacks, in which the windings of each module connect in series. Aiming at this electrical connection, we conduct research on electromagnetic and synchronous characteristics. Firstly, a two-module PMLSM is created as a case. Secondly, accurate mathematical models considering coupling inductance for this novelty structure are established, which are essential to driving control. The synchronous characteristics of the two-module are then compared with the independent control of each module. Furthermore, this comparison is conducted under both external and no external disturbance. Finally, experimental results verify the correctness of mathematical models, and reveal that this novel technique could eliminate control time delay and acquire better anti-disturbance performance between the two-module.

Stability and Synchronous Characteristics of Dual-Rotors Vibrating System Considering the Material Effects

Stability and Synchronous Characteristics of Dual-Rotors Vibrating System Considering the Material Effects

Research on the Synchronization and Shock Characteristics of an Air Adjustment Mechanism for Cluster-Type DTH Hammers under Partial Loads

Cluster down-the-hole (DTH) hammers are often used in large-diameter hard rock drilling operations. Due to complex rock formation conditions, cluster DTH hammers cannot adjust the working airflow in time according to rock formation conditions, resulting in frequent damage to cluster DTH hammers and low work efficiency. Aiming at this problem, this paper proposes an airflow adjustment mechanism as a solution. In this paper, the operation stability and airflow adjustment characteristics of the adjustment mechanism are studied. The impact characteristics and driving force variation characteristics of the adjustment mechanism under different speeds and loading modes are analyzed, and the results show that the movement impact of the adjustment mechanism increases with the increase of the movement speed of the driving actuator under the same loading mode. With the increase of the eccentric load, the critical movement speed of the driving actuator decreases when the adjustment mechanism moves without impact. The test verifies the synchronization characteristics of the adjustment mechanism under different load modes and different control valves. The results show that, under the condition of uniform load, the synchronization accuracy of the dividing/focusing valve and the proportional valve is good. With the increase of the eccentric load difference, the synchronization performance of the dividing/focusing valve becomes worse, and the average error increases. The test results in this paper are of great significance for guiding the engineering design of cluster DTH hammers.

Influence and comparison of P/Q-control based VSC-HVDC system on the grid power oscillation damping

To analyze the dynamic process of VSC-HVDC system actively participating in suppressing the grid power oscillation, under the electromechanical time control scale, this paper establishes the linear mathematical model of the VSC-HVDC connected to the single machine infinity system, and the dynamic interaction relationship between the controlled active and reactive power injected into the power grid by VSC-HVDC, moreover, the synchronization, inertia and damping level are investigated by the electrical torque method in this paper. The study shown that when the rotor speed is selected as the grid state quantity feedback signal, adjusting the PID controller gain of rotor speed control loop can effectively adjust the VSC device’s active and reactive output power to improve the system damping level, synchronous characteristics and inertial effects, which can thus restrain the rotor speed deviation and speed change rate under oscillating conditions and improve the system frequency stability. In addition, this paper proposes an index for the proportion of inverter station regulation capacity, which proves that the VSC-HVDC operating in active power control strategy has better suppression effect on power oscillation than reactive power control, reducing the design capacity and cost of inverter stations. Finally, the simulation proves the dynamic process analysis correctness of VSC-HVDC suppressing the grid power oscillation in this paper.

Abstract P4-07-04: Bc cancer ipsilateral breast tumor recurrence (BCC IBTR) nomogram

Abstract INTRODUCTION:. Local and systemic treatments for breast cancer have evolved in the past decades. This study reports the development of a modern population-based nomogram to individualize local recurrence (LR) risk estimates for patients treated with breast conservation surgery (BCS). The magnitude of benefit of adjuvant breast radiotherapy (BRT) depends on individual patient, tumor, and treatment characteristics (1). Nomograms can provide accurate predictions of LR and the absolute LR benefit of BRT that can assist patients in making informed decisions regarding BRT. This nomogram is based on a large cohort of women with prospectively captured biomarker data and modern systemic therapies including anti-human epidermal growth factor receptor 2 (HER2) therapy. METHOD:. Study Population:. The study cohort included women treated curatively for newly diagnosed breast cancer between 1st January 2005 and 31st December 2014. Inclusion criteria were: age >16 years, invasive ductal or lobular carcinoma, stage I-III, and BCS. Patients with metastatic disease, prior or synchronous contralateral breast cancer, unknown tumor or treatment characteristics, or treated with neoadjuvant therapy or mastectomy were excluded. Nomogram Development and Validation:. Age, tumor size, number of positive lymph nodes, grade, margin status, lymphovascular invasion (LVI), extensive intraductal component (EIC), estrogen receptor (ER), progesterone receptor (PR), HER2 status, use of chemotherapy, hormonal therapy, and radiotherapy with or without boost were recorded for each patient. The endpoint was LR as the first event. Fine and Gray’s competing risk model, with distant recurrence and death as competing risks, was used for the multivariable analysis, adjusting for demographics, tumor, and treatment factors. Hazard ratio (HR) and 95% confidence interval (CI) for each variable were calculated. The multivariable model forms the basis for the nomogram, which is being internally validated using the bootstrap and cross-validation. RESULTS:Of 11,310 patients, there were 429 LR (crude risk = 3.8%). The HR and 95% CIs from the Fine and Gray model for each of the variables in the nomogram are presented in the table. Age, number of positive nodes, grade, ER, LVI, margins, hormone therapy, chemotherapy, and radiotherapy were independent prognostic factors for LR. For patients treated with RT, the predicted 10-year cumulative incidence of LR ranged from 2.4% in patients with low-risk disease to 12.5% in patients with high-risk disease. CONCLUSION:A new nomogram for local recurrence, based on patients who had ER/PR/HER2 testing and who received modern systemic therapies is being developed. It will assist clinicians and patients individualize estimates of local recurrence risk and improve shared decision-making regarding the use of BRT in contemporary practice. REFERENCES:. (1)Sanghani, M., et al J Clin Oncol.,2010; 28(5), 718-722. Cox regression hazard ratios and confidence intervals for variablesCharacteristicHR95%CIp-valueAge0.980.970.99<0.01T-size1.011.001.010.14No. nodes1.041.011.070.005GradeGrade1---Grade21.751.322.33<0.001Grade32.541.813.56<0.001ERNeg---Pos1.441.012.060.046PRNeg---Pos0.790.611.030.084Her2Neg---Pos0.960.731.250.8LVINeg---Pos1.961.552.47<0.001Unk1.360.722.580.3Margin StatusNeg---Close1.411.081.840.011Pos1.681.082.590.200Extensive DCISNo---Yes1.140.841.550.4HTNo---Yes0.520.410.65<0.001ChemoNo---Yes0.540.420.71<0.001RTNo---Yes0.330.260.42<0.001BoostNo---Yes0.800.621.040.094 Citation Format: Dylan Narinesingh, Alan Nichol, Pauline Truong, Lovedeep Gondara, Caroline Speers, Laveniya Kugathasan, Caroline Lohrisch, Dave Voduc, Nafisha Lalani. Bc cancer ipsilateral breast tumor recurrence (BCC IBTR) nomogram [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-07-04.

Revealing spatiotemporal correlation of urban roads via traffic perturbation simulation

• We proposed a novel method to evaluate the spatiotemporal correlation of urban road networks. • The proposed method is based on the traffic response of road segments caused by traffic perturbations. • We simulated the dynamic variation of local correlation. • The simulation showed the spatiotemporal synchronization characteristics or spatiotemporal ripple effect of the local road correlation. Unbalanced interactions in cities result to a correlation between urban road segments with spatiotemporal heterogeneity. The accurate detection of this spatiotemporal correlation can significantly contribute to traffic congestion prediction and sustainable urban operations. However, the spatiotemporal nonstationarity of the traffic flow causes dynamic uncertainty in road network correlation. Therefore, we proposed a novel method to evaluate the spatiotemporal correlation of road networks. First, a dynamic chain propagation model of traffic perturbation was constructed to track the propagation process of traffic response. Then, the time and spatial lag operators were designed based on the perturbation response and utilized to detect the local spatiotemporal correlation of the road network. Finally, a new remote correlation measurement model was proposed by capturing the traffic flow contribution. Experiments demonstrated that the average local correlation of an urban road network is 0.83 in first-order neighborhood segments, which decreases to 0.72 in third-order neighborhood segments with the synchronous increase of space-time lag operators. Moreover, the correlations of downstream segments are on average 11.6% higher than those of upstream segments. These results can provide targeted decision support for preventing the potential spread of traffic congestion, reducing urban air pollution, and promoting sustainable urban development.

Combined higher-order interactions of mixed symmetry on the sphere.

We consider systems of N particles interacting on the unit sphere in d-dimensional space with dynamics defined as the gradient flow of rotationally invariant potentials. The Kuramoto model on the sphere is a well-studied example of such a system but allows only pairwise interactions. Using the Kuramoto model as a guide, we construct n-body potentials from products and sums of rotation invariants, namely, bilinear inner products and multilinear determinants, which lead to a wide variety of higher-order systems with differing synchronization characteristics. The connectivity coefficients, which determine the strength of interaction between any set of n distinct nodes, have mixed symmetries, which follow from those of the symmetric inner product and the antisymmetric determinant. We investigate n-body systems in detail for n⩽6, both as isolated systems and in combination with lower-order systems, and analyze their properties as functions of the coupling constants. We show by example that in many cases, multistable states appear only when we forbid self-interactions within the system.

라인 기동식 릴럭턴스 전동기의 동기화 특성에 관한 연구

Line-start synchronous reluctance motor(LS-SynRM) has the high efficiency than the induction motor that is almost used in the industrial application. However, LS-SynRM must be operated in the synchronous speed for the high efficiency. When the load has high inertia, LS-SynRM fail to reach the synchronous speed. In this paper, the synchronization characteristics of LS-SynRM are analyzed based on the mathematical model and finite element analysis (FEA). The synchronization characteristics and the synchronous process of LS-SynRM are analyzed based on the mathematical model in s-δ plane. Furthermore, the condition of the synchronization is obtained by the kinetic energy and the motor energy. The three models are selected according to the rotor bar to analyze the synchronization characteristics using FEA. Using the time-harmonic analysis, the equivalent circuit parameters of the three models are calculated, and the starting characteristics and performance of LS-SynRM are compared.

Self-Synchronization Theory of Circular Symmetrical Four Motors

The synchronization characteristics of the circularly symmetrical four-vibrators vibration system are studied. Firstly, the dynamic model of this type of vibration system is established, and the Lagrange equation is used to derive the differential equation of motion. Secondly, the steady-state solution of the vibration system is obtained by averaging the phase of the eccentric rotor of the four exciters in the vibration system, and Hami is used. The frame principle deduces the synchronization conditions and stability conditions for the four vibration exciters of this type of vibration system to achieve synchronous motion. Finally, the correctness of the theoretical analysis is verified by numerical simulation. The relevant research results can provide a theoretical basis for the design of the circularly symmetrical four-vibrators vibration machine.

Asynchronous Non–uniform Distributed Multi–target Tracking Filter Based on Asymmetric Alpha–divergence Consensus

With more and more extensive application of target tracking, distributed multi–target tracking (DMT) becomes an important research direction. However, the synchronization characteristics of some sensor networks can not be guaranteed due to communication delay, non–uniform sampling and so on. Therefore, a DMT algorithm for asynchronous non–uniform multi–sensor networks is studied in this paper. Firstly, by using the cardinalized probability hypothesis density (CPHD) based on continuous–discrete multi–target dynamic (CD) model (CD-CPHD), a CD–CPHD algorithm with multi–step birth process and time–triggered structure (TCD–CPHD) is proposed; Secondly, an asymmetric alpha–divergence (AAD) based adaptive computing structure of time–trigger index is designed to reduce the communication rate of TCD–CPHD; Thirdly, the fusion rule of AAD consensus is derived to construct the fusion process of the proposed algorithm; Finally, by combining the above structures and the fusion rule, the implementation process of the proposed algorithm is given. Theoretical analysis and exhaustive experimental analysis show the effectiveness of the proposed algorithm.

Phenology of Tree Species in an Open Ombrophilous Forest: Bases for Silviculture and Conservation

Phenological information contribute to silvicultural actions and conservation strategies. Here, we carried out the phenological monitoring of six tree species that were prominent in the structure of an open ombrophilous forest fragment in northeastern Brazil. Over two years, among September 2015 and August 2017, eight individuals of each species (48 trees in total) were visited every two weeks to record the reproductive and leaf phenophases, following the Fournier intensity scale. We calculated the intraspecific synchrony of the phenophases and the correlation of the phenophases of each species with meteorological variables (temperature, air precipitation and photoperiod). The species showed synchronous characteristics for the phenophases. Precipitation stood out in terms of a higher frequency of significant relationships with the reproductive phenophases. The results indicates that the end of the dry season is the most favorable period for seed collection and the monitoring of dispersers in this type of tropical forest.

An endogenous basis for synchronisation characteristics of the circadian rhythm in proliferating Lemna minor plants.

The circadian clock is a cell-autonomous system that functions through the coordination of time information in the plant body. Synchronisation of cellular clocks is based on coordination mechanisms; the synchronisation characteristics of proliferating plants remain unclear. The bioluminescence circadian rhythms of fronds (leaf-like plant units) of proliferating Lemna minor plants carrying a circadian bioluminescence reporter, AtCCA1:LUC, were spatiotemporally analysed at a cell-level resolution. We focused on spontaneous circadian organisation under constant light conditions for plants with light:dark treatment (LD grown) or without it (LL grown). Fronds developing even from an LL-grown parental frond showed coherent circadian rhythms among them. This allowed the maintenance of circadian rhythmicity in proliferating plants. Inside a frond, a centrifugal phase/period pattern was observed in LD-grown plants, whereas various phase patterns with travelling waves were formed in LL-grown plants. These patterns were model simulated by local coupling of heterogeneous cellular circadian oscillators with different initial synchronous states in fronds. Spatiotemporal analysis of the circadian rhythms in proliferating plants reveals spontaneous synchronisation manners that are associated with local cell-cell coupling, spatial phase patterns and developmental stages.

Stability and synchronous characteristics of a two exciters vibration system considering material motion

Nowadays, two exciters vibration system played an indispensable role in a majority of machinery and devices, such as vibratory feeder, vibrating screen, vibration conveyer, vibrating crusher, and so on. The stability of the system and the synchronous characteristics of two exciters are affected by material motion. However, those effects of material on two exciters vibration system were studied very little. Based on the special background, a mechanical model that two exciters vibration system considering material motion is proposed. Firstly, the system's dynamic equations are solved by using Lagrange principle and Newton's second law. Then, the motion stability of the system when material with different mass move on the vibrating body is analyzed by [Formula: see text] mapping and numerical simulation methods, and the motion forms of the material are also studied. Meanwhile, the frequency responses of the vibrating body are analyzed. Finally, the influence of material on the phase difference of the two exciters is revealed. It can be concluded that with the mass ratio of the material to the vibrating body increasing, the system's motion evolves from stable periodic motion to chaotic state, the synchronization ability of two exciters decline, and the unpredictability of abrupt change about the phase difference increases. Further, the uncertainties of both the abrupt change of phase difference and the collision location affect each other and eventually lead to the instability of the system.

A Novel Evaluation Strategy to Artificial Neural Network Model Based on Bionics.

With the continuous deepening of Artificial Neural Network (ANN) research, ANN model structure and function are improving towards diversification and intelligence. However, the model is more evaluated from the pros and cons of the problem-solving results and the lack of evaluation from the biomimetic aspect of imitating neural networks is not inclusive enough. Hence, a new ANN models evaluation strategy is proposed from the perspective of bionics in response to this problem in the paper. Firstly, four classical neural network models are illustrated: Back Propagation (BP) network, Deep Belief Network (DBN), LeNet5 network, and olfactory bionic model (KIII model), and the neuron transmission mode and equation, network structure, and weight updating principle of the models are analyzed qualitatively. The analysis results show that the KIII model comes closer to the actual biological nervous system compared with other models, and the LeNet5 network simulates the nervous system in depth. Secondly, evaluation indexes of ANN are constructed from the perspective of bionics in this paper: small-world, synchronous, and chaotic characteristics. Finally, the network model is quantitatively analyzed by evaluation indexes from the perspective of bionics. The experimental results show that the DBN network, LeNet5 network, and BP network have synchronous characteristics. And the DBN network and LeNet5 network have certain chaotic characteristics, but there is still a certain distance between the three classical neural networks and actual biological neural networks. The KIII model has certain small-world characteristics in structure, and its network also exhibits synchronization characteristics and chaotic characteristics. Compared with the DBN network, LeNet5 network, and the BP network, the KIII model is closer to the real biological neural network.

On the Synchronization Behavior of Coupled Friction-Induced Oscillators Subjected to Base Excitation

Abstract The primary objective of this paper is to analyze the synchronization phenomena in a coupled friction-induced oscillator consisting of two cantilever beams with tip-masses subjected to base excitations. The coupling is achieved by connecting a linear spring between the tip-masses, which are in frictional contact with a rigid rotating disk. The Pearson time correlation coefficient is used to measure the strength and mode of synchronization between the oscillations of the coupled system. Periodicity of the motions is determined by evaluating the Poincaré map wherein the zero velocity crossing from positive to negative is considered as the Poincaré section. The fundamental frequency of the coupled motion and its harmonics are obtained from the Fast Fourier Transform (FFT) of the time responses. A bifurcation study is conducted to identify the periodicity of motion of both the uncoupled and coupled systems. The coupled system is found to be synchronized for the single-periodic, multiperiodic, and quasi-periodic motions, but not for chaotic motions. Multiple basins of attractions of initial conditions corresponding to different synchronization characteristics are observed. The coupled system shows a large dependence of the mass ratio detuning factor (MRDF) on the synchronization characteristics; in-phase synchronization is obtained for smaller MRDF, which eventually becomes out-of-phase for larger MRDF. A special study conducted confirms that the coupling can be used to control the amplitude as well as the stick-phase of motion in friction oscillators.

Predicting students at risk of academic failure using ensemble model during pandemic in a distance learning system

Predicting students at risk of academic failure is valuable for higher education institutions to improve student performance. During the pandemic, with the transition to compulsory distance learning in higher education, it has become even more important to identify these students and make instructional interventions to avoid leaving them behind. This goal can be achieved by new data mining techniques and machine learning methods. This study took both the synchronous and asynchronous activity characteristics of students into account to identify students at risk of academic failure during the pandemic. Additionally, this study proposes an optimal ensemble model predicting students at risk using a combination of relevant machine learning algorithms. Performances of over two thousand university students were predicted with an ensemble model in terms of gender, degree, number of downloaded lecture notes and course materials, total time spent in online sessions, number of attendances, and quiz score. Asynchronous learning activities were found more determinant than synchronous ones. The proposed ensemble model made a good prediction with a specificity of 90.34%. Thus, practitioners are suggested to monitor and organize training activities accordingly.

The dynamics of synchronization of two-stage van der Pol generator

Results of numerical simulation of self-oscillations synchronization process in two-cascade ring generator van der Pol by harmonic signal are presented. Studies were carried out within the framework of the DT- model of the dynamic system. The model was developed on the basis of the principle of compliance within the framework of the method of slowly changing amplitudes of characteristics of a discrete system with characteristics of an analog prototype. Shortened equations for complex oscillation amplitudes in generator stages are obtained. It was found that in an autonomous system there is an effect of bistability of amplitudes. In the synchronization mode with an external harmonic signal, solutions of shortened equations made it possible to calculate amplitude-frequency and phase-frequency characteristics of synchronous oscillations. It is shown that transitions between bistable states are observed in the synchronous oscillation holding band. Differences of frequency characteristics of synchronization of classical and two-stage oscillators van der Pol were analyzed.