Articoli di riviste: "Synchronous dynamic"

1

Natanzon, Assaf, e Eitan Bachmat. "Dynamic Synchronous/Asynchronous Replication". ACM Transactions on Storage 9, n. 3 (1 agosto 2013): 1–19. http://dx.doi.org/10.1145/2501620.2508011.

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Natanzon, Assaf, e Eitan Bachmat. "Dynamic Synchronous/Asynchronous Replication". ACM Transactions on Storage 9, n. 3 (agosto 2013): 1–19. http://dx.doi.org/10.1145/2508011.

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Li, Yi Min, Zhi Yong Hao e Jin Li. "Analysis and Research of Dynamic Characteristics of Synchronous Belt of a Diesel Using Multi-Body Dynamics". Applied Mechanics and Materials 97-98 (settembre 2011): 721–25. http://dx.doi.org/10.4028/www.scientific.net/amm.97-98.721.

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The dynamic tension of synchronous belt and pulleys forces are obtained by analyzing the dynamic characteristics of timing drive system of a diesel based on muti-body dynamics. The effects of crankshaft speed fluctuation and other excitations on the dynamics characteristics of synchronous belt are illustrated. After the analysis, it is found that crankshaft speed fluctuation has a great influence on the linear and transversal vibrations of synchronous belt. Comparing the simulation results of the original timing system and the one optimized, it is found that the modal frequency of synchronous belt depends on its span. Therefore it is important to control the span of belt and arrange the tensioner pulley properly for timing system design.

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Chen, Qi, e Jinlei Li. "Field Dynamic Balancing for Magnetically Suspended Turbomolecular Pump". Sensors 23, n. 13 (5 luglio 2023): 6168. http://dx.doi.org/10.3390/s23136168.

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A field dynamic balancer is crucial to the applications of magnetically suspended turbomolecular pumps. Therefore, this paper presents a novel field dynamic balancing method based on autocentering control mode without any additional instrumentation. Firstly, the dynamics of the active magnetic bearing rotor system with unbalance are modeled. Through model analysis, it was found that making the rotor rotate around the geometric axis can improve the accuracy of dynamic balancing. Secondly, the relationship between the correcting masses and the synchronous currents based on the influence coefficient method is established. Then, an autocentering controller is designed to make the rotor rotate around the geometric axis. The synchronous currents can be detected and extracted by the current transducers to calculate the unbalance correction mass. Finally, the experimental results show that this novel field dynamic balancing method can effectively eliminate the majority of rotor unbalance. Compared with the original unbalance of a rotor, the synchronous current in the A-end has been reduced by 71.4% and the synchronous current in the B-end, by 90.8% with the proposed method.

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Boldi, Paolo, e Sebastiano Vigna. "Universal dynamic synchronous self-stabilization". Distributed Computing 15, n. 3 (1 luglio 2002): 137–53. http://dx.doi.org/10.1007/s004460100062.

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Johannesson, Tomas, e Martin Distner. "Dynamic Loading of Synchronous Belts". Journal of Mechanical Design 124, n. 1 (1 maggio 2000): 79–85. http://dx.doi.org/10.1115/1.1426088.

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In automotive timing belt drives friction history effects must be taken into concern due to rapidly changing loads. Here a spring based model capable of handling dynamic load conditions is presented. The model also covers partial meshing effects and utilizes Coulomb friction. The model shows good agreement with experimental data found in literature. It is proven that when simulating synchronous belt drives during rapidly changing load conditions, using models for quasi-static load conditions stepwise are not sufficient.

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Matrosov, Valerij, e Dmitry Kasatkin. "Particularities of dynamics of three cascade-coupled phase-locked loops". Izvestiya VUZ. Applied Nonlinear Dynamics 12, n. 1-2 (20 giugno 2004): 159–68. http://dx.doi.org/10.18500/0869-6632-2004-12-1-159-168.

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Results of investigations of dynamic modes of three phase-locked loops are presented. The influence of coupling parameters and initial frequency mismatch on synchronous and quasi-synchronous modes is studied. Domains of quasi-synchronous oscillations of controlled oscillators are allocated in the parameter space. The comparative analysis of dynamics of ensembles, consisting of two and three oscillators is carried out.

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Shi, Yao Chen, Zhan Guo Li e Xiu Guang Yang. "The Tooth Profile of Car Synchronous Belt Influencing on the Stress Distribution". Applied Mechanics and Materials 602-605 (agosto 2014): 339–41. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.339.

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This paper aim at the ZA type car synchronous belt, using the CATIA software create the synchronous belt and pulleys 3D model, divide synchronous belt mesh with ANSYS software, and import into the multi-body dynamics software RecurDyn and build up the dynamic simulation model of the car synchronous belt transmission through the MFBD (more flexible body dynamics) techniques. Analyzed the transmission performance of the synchronous belt、contact stress of tooth surface and tension stress. It propose the stress distribution between belt and pulley, and the distribution state of the tensile stress. It provide a digital simulation and design method to design the car synchronous belt tooth shape, analysis the transmission performance and select the material of rubber and the reinforcing cords.

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Ramachandra, Shruthi, Mala R.C. e H. V. Gururaja Rao. "Dynamic bifurcation analysis and mitigation of SSR in SMIB system". Indonesian Journal of Electrical Engineering and Computer Science 15, n. 3 (1 settembre 2019): 1128. http://dx.doi.org/10.11591/ijeecs.v15.i3.pp1128-1137.

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This paper presents a detailed study on Sub-synchronous resonance in a Single machine connected to an infinite bus system by employing Bifurcation Theory. The synchronous machine model considered is a two-axis model, the turbine system is a six mass system. A comparative study of Sub-synchronous resonance for the two-axis synchronous machine models 1.1, 2.1 and 2.2 under constant excitation is presented in this paper. The effect of adding an exciter, power system stabilizer and Static Synchronous Series Compensator to the SMIB system, incorporated with a 2.2 synchronous machine model on the bifurcations of SSR is also investigated. The results obtained on replacing the fixed series compensation of the line by Static Synchronous Series Compensator resulted in the mitigation of Sub-synchronous Resonance. The results obtained for all the above-considered cases are compared with eigenvalue analysis and validated using transient analysis<strong>.</strong>

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Kim, Young Hwan, e Yunseok Rhee. "Distributed and Parallel Deep Learning Architecture Exploiting Dynamic Stale Synchronous Parallel Method". Journal of Digital Contents Society 20, n. 2 (28 febbraio 2019): 387–94. http://dx.doi.org/10.9728/dcs.2019.20.2.387.

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Podymaka, Valeriy. "DYNAMIC CONDITIONS OF COMPENSATED SYNCHRONOUS MACHINE". Science Journal Innovation Technologies Transfer, n. 2019-4 (1 settembre 2019): 76–82. http://dx.doi.org/10.36381/iamsti.4.2019.76-82.

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The dynamic behavior of synchronous machine with longitudinal-transverse excitement by maintenance of the rotor overhang corner as equal zero are considered. The given condition is named as compensated and correspond with full compensation of transverse armature reaction by magnetizing force of transverse excitement winding. In such machine is absented the limit of steady-state overload, but active and reactive components of load current are concurrent as projections of load current image vector on orthogonal axes of machine inductor. The research aim is a determination of steady-state stability criterion of compensated synchronous machine working on powerful electrical system. The researches are organized in assumption of inductor current invariance and at neglect of stator windings time constant. The electromagnetic moment expression of longitudinal-transverse excitement synchronous machine in compensated work condition is received as a result of analysis of the spatial vector diagrams and equations. The expression analysis has allowed to find the criterion of rotor creepage stability and to examine the steady-state stability of the machine in different work conditions. It is shown that machines stability factor is defined by not only the reactive power of machine short circuit, but also associated reactive power.

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Manes, G., P. Tortoli, F. Andreuccetti, G. Avitabile e C. Atzeni. "Synchronous dynamic focusing for ultrasound imaging". IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 35, n. 1 (gennaio 1988): 14–21. http://dx.doi.org/10.1109/58.4143.

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13

Fang, Pan, e Yongjun Hou. "Synchronization characteristics of a rotor-pendula system in multiple coupling resonant systems". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, n. 10 (30 maggio 2017): 1802–22. http://dx.doi.org/10.1177/0954406217711468.

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The problem is motivated by observations of a rotor-pendula system, which derived from a new shale shaker. To grasp the dynamic characteristics of the shale shaker, the key research is exploring the synchronous mechanism for the system, since synchronous state between rotors is closely related to the dynamic characteristics of the system. In this paper, the dynamic equation of the rotor-pendula system is firstly derived by applying Lagrange’s equations. Through Laplace’s transformation method, the approximate responses of the system in synchronous state are obtained, which is determined coupling coefficients and synchronous state of the system. Then, the synchronous balance equation and the stability criterion of the system are obtained with Poincaré method on which stable phase difference and synchronous behavior can be ascertained. To verify the correctness of the theoretical analysis, numerical simulations are implemented by Runge–Kutta method, and it is shown that the synchronous behavior is determined by the geometry parameters, coupling coefficients, and rotor rotation direction.

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Shabanov, Vitaly, Aigul Basyrova e Nikita Kantyukov. "STABILITY ASSESSMENT OF SYNCHRONOUS MOTORS IN THE PLANE OF TWO ANGLES". Electrical and data processing facilities and systems 18, n. 2 (2022): 73–81. http://dx.doi.org/10.17122/1999-5458-2022-18-2-73-81.

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Relevance The main technological installations of the oil and gas industry require power supply of the first category and are fed from two independent sources. Possible short-term interruptions of power supply of such installations by their duration should not lead to a violation of the stability of electric motors and disruption of technological processes. The problem of stability at enterprises equipped with automatic standby switching devices with self-starting of synchronous motors after a short interruption of power supply is especially relevant. Therefore, the assessment of conditions for preserving the dynamic stability of synchronous motors after a short interruption of power supply is an urgent task. Aim of research Based on the method of areas, develop a method for assessing the dynamic stability of synchronous motors in the plane of two parameters. Methods The article uses dynamic stability areas in the plane of two angles to assess the dynamic stability of synchronous motors: the load angle of the synchronous motor in the pre-emergency mode δ0 and the inclusion angle δвкл between the mains voltage vectors and the residual voltage on the section that lost power, in the emergency mode. Results The dynamic stability area in the plane of two angles is plotted: the load angle δ0 and the turn-on angle δвкл. The boundary lines of dynamic stability area are plotted for the range of values of load angles, in which the static stability of the synchronous motor in the pre-emergency mode is preserved. On the example of synchronous motor of STD-2500 type, the definition of the dynamic stability area in the plane of parameters under study is shown. It is shown that the region of dynamic stability in the plane of two angles can be transformed into the dynamic stability area of other investigated parameters.

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Zhong, You Kun. "Design of Synchronous Machine Model Based on PRO/E and Dynamic Simulation". Applied Mechanics and Materials 246-247 (dicembre 2012): 1220–25. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.1220.

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With the increasing of the number of cars, people are also getting higher and higher demands on the performance of the car, and especially pay attention to the improvement and optimization of automobile transmission system. The transmission is a key part of automobile transmission system, and transmission performance and stability depend on the synchronous machine, so in order to make the vehicle transmission system with higher efficiency, it is necessary to study the synchronous machine. On the basis of elaborating synchronous machine working principle, the use of dynamics theory to establish mathematical model of synchronous machine system, and to carry out the simulation of synchronous machine three-dimensional model in PRO/E environment, then the use of virtual prototype technology to optimize the parameters of synchronous machine, thereby improving the performance of synchronous machine.

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16

Zhang, Jin Zhao. "Vector Control for Connectionless Two-Motor Synchronous System". Advanced Materials Research 588-589 (novembre 2012): 492–95. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.492.

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According to two three-phase asynchronous motors system running by connectionless-mode, and considering the system to be required to run in strict synchronous way under different load, the method of field-oriented vector control is used. Thus, the control loops of rotor flux, torque and rotor speed are constructed to make two-motor system run synchronously by torque distribution. The simulation results illustrate its effectiveness and good dynamic and static performance.

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Yu, Yang, Zhongjie Wang e Chengchao Lu. "An extended Kalman particle filter for power system dynamic state estimation". COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 37, n. 6 (5 novembre 2018): 1993–2005. http://dx.doi.org/10.1108/compel-11-2017-0493.

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Purpose The purpose of this paper is to propose an extended Kalman particle filter (EPF) approach for dynamic state estimation of synchronous machine using the phasor measurement unit’s measurements. Design/methodology/approach EPF combines the extended Kalman filter (EKF) with the particle filter (PF) to accurately estimate the dynamic states of synchronous machine. EKF is used to make particles of PF transfer to the likelihood distribution from the previous distribution. Therefore, the sample impoverishment in the implementation of PF is able to be avoided. Findings The proposed method is capable of estimating the dynamic states of synchronous machine with high accuracy. The real-time capability of this method is also acceptable. Practical implications The effectiveness of the proposed approach is tested on IEEE 30-bus system. Originality/value Introducing EKF into PF, EPF is proposed to estimate the dynamic states of synchronous machine. The accuracy of a dynamic state estimation is increased.

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Li, Ming, Zi Gang Li e Ping Xue. "Nonlinear Dynamic Behaviors of Rotor System with Misaligned Journal Bearings". Applied Mechanics and Materials 271-272 (dicembre 2012): 1032–38. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1032.

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The dynamic modeling of a rotor system on misaligned journal bearings is discussed and its nonlinear dynamic behaviors are considered in this paper. Firstly, a dynamic model of six degrees of freedom system is established under the conditions of the long bearings, small bearing misalignment and mass unbalance. Then, the nonlinear dynamics of the rotor-bearing system, such as the displacement response and its frequency spectrum, rotor orbit and its Poincare map are analyzed by the Runge-Kutta method. The results show that at low speed the steady-state responses of the rotor system in lateral direction is synchronous, as the speed increases a serious of bifurcation phenomena and chaotic oscillations occur. In many cases, there exist the integer multiples components of the rotating speed except the synchronous one in displacement responses.

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Wang, Peng, Hongwei Ma, Ye Zhang, Xiangang Cao, Xudong Wu, Xiaorong Wei e Wenjian Zhou. "Trajectory Planning for Coal Gangue Sorting Robot Tracking Fast-Mass Target under Multiple Constraints". Sensors 23, n. 9 (30 aprile 2023): 4412. http://dx.doi.org/10.3390/s23094412.

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Aiming at the problems of grab failure and manipulator damage, this paper proposes a dynamic gangue trajectory planning method for the manipulator synchronous tracking under multi-constraint conditions. The main reason for the impact load is that there is a speed difference between the end of the manipulator and the target when the manipulator grabs the target. In this method, the mathematical model of seven-segment manipulator trajectory planning is constructed first. The mathematical model of synchronous tracking of dynamic targets based on a time-minimum manipulator is constructed by taking the robot’s acceleration, speed, and synchronization as constraints. The model transforms the multi-constraint-solving problem into a single-objective-solving problem. Finally, the particle swarm optimization algorithm is used to solve the model. The calculation results are put into the trajectory planning model of the manipulator to obtain the synchronous tracking trajectory of the manipulator. Simulation and experiments show that each joint of the robot’s arm can synchronously track dynamic targets within the constraint range. This method can ensure the synchronization of the position, speed, and acceleration of the moving target and the target after tracking. The average position error is 2.1 mm, and the average speed error is 7.4 mm/s. The robot has a high tracking accuracy, which further improves the robot’s grasping stability and success rate.

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Zhao, Guo Hua, e Jian Guo Chen. "Application Research on Learning Strategy Control of Daul-Cylinder Synchronous Movement". Applied Mechanics and Materials 423-426 (settembre 2013): 2890–93. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.2890.

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The hydraulic control system of the dual-cylinder synchronous motion is designed, and the basic operating principle of the dual-cylinder synchronous motion system is discussed.The self-learning control algorithm of dual-cylinder synchronous motion is introduce, the synchronous control circuit is discussed .Dynamic simulation of dual-cylinder synchronous motion control system is presented, and factors affecting synchronous performance are analyzed.

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Andreyev, Yury. "Global synchronization in lattices of chaotic maps with limited number of connections". Izvestiya VUZ. Applied Nonlinear Dynamics 7, n. 1 (1999): 12–28. http://dx.doi.org/10.18500/0869-6632-1999-7-1-12-28.

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Stability of the global synchronous mode of chaotic map lattices is investigated by means of direct calculation of the stability conditions, and by means of numerical simulation. The lattices with local connections are shown to have a limit value of the Lyapunov exponent of the lattice maps, above which the global synchronous mode loses stability. The synchronous mode in large lattices is found impossible due to the local nature, i.e., «short range» of the connections. We propose some approaches to modification of the dynamic system structure that can provide stability of the synchronous mode, such as tuning the dynamic mode of the lattice maps, extension of the local neighborhood, use of nonlocal static and dynamic connections, and introduction of an external control node (a pacemaker). In the model with the pacemaker, a spatial synchronous lattice mode is revealed, different from the pacemaker mode («generalized» synchronization).

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McHugh, J. D. "Estimating the Severity of Sub-Synchronous Shaft Vibrations Within Fluid Film Journal Bearings". Journal of Tribology 108, n. 2 (1 aprile 1986): 249–55. http://dx.doi.org/10.1115/1.3261172.

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Frequency analyzers sometimes show that shaft proximity probe signals have both a subsynchronous and synchronous component. For shafts supported on fluid-film bearings, a widely-held concern exists over any subsynchronous vibrations, even when the levels are limited in magnitude. Little information has existed for judging the impact of such vibrations on the bearing. In the present paper, a rational method is developed for estimating the dynamic load imposed on a bearing by combinations of sub-synchronous and synchronous vibration. Curves are provided for several bearing geometries which can be used to estimate the maximum dynamic load produced by such vibrations. The curves may also be used to estimate the combination of sub-synchronous and one-per-rev shaft vibrations permissible for some limiting dynamic bearing load.

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Fang, Pan, Huan Peng, Du Changcheng, Min Zou, Duyu Hou, Mingjun Du e Guodong Chai. "Synchronous state of unbalanced rotors in a three-dimensional space and far-resonance system". Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 234, n. 1 (27 novembre 2019): 108–22. http://dx.doi.org/10.1177/0954408919889416.

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The unreasonable dynamic characteristics results in decrease of screening efficiency of the vibrating screen. However, the synchronous behavior of motors is key factor to determine dynamic characteristics of the screens. In this paper, two unbalanced rotors actuated with motors in a three-dimensional space are proposed. To understand the synchronous mechanism, the dynamic equation of the system is firstly confirmed based on Lagrangian formulation; meanwhile, synchronization condition of the system is calculated with average and small parameter method; then, synchronization stability of the system is explored by Lyapunov method; finally, some numerical simulations are given to validate the theoretical computations. It is found that, to implement the stable synchronous rotation between the rotors, the values of the parameter in this system must be satisfied by synchronous condition and synchronous stability; the synchronous state is determined by the rotation direction, the damping ratio, the frequency ratio, and the motor position; the system is a planar motion when the identical mass rotors oppositely actuated, but the system is a spatial motion in the other cases.

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Hwang, Yunn Lin, e Van Thuan Truong. "A Synchronous Approach for Numerical Simulation of Machine Tools". Key Engineering Materials 642 (aprile 2015): 317–22. http://dx.doi.org/10.4028/www.scientific.net/kem.642.317.

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In this paper, a synchronous approach for dynamic simulation of machine tools is described. Computer Aided Engineering (CAE) method models and analyzes a dynamical parameter prototype of machine tools. In which, the flexible structure, interactive movement, non-linear factor effects as well as characteristics of resonance frequencies and mechanical transfer function are considered. The integrating Finite Element Method (FEM), Multi-Body Dynamics (MBD) and control carries out a solution of machine tools simulation for predicting dynamic machine behaviors. The static analysis and modal analysis of components are presented with sample examples. Cybernetic characteristics like Bode diagram and such a controller are implemented for movement tailors. The synchronous approach deduces a practically technical method for machines tools.

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Yu, Xian, Yinxin Bao e Quan Shi. "Dynamic multiple-graph spatial-temporal synchronous aggregation framework for traffic prediction in intelligent transportation systems". PeerJ Computer Science 10 (29 febbraio 2024): e1913. http://dx.doi.org/10.7717/peerj-cs.1913.

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Accurate traffic prediction contributes significantly to the success of intelligent transportation systems (ITS), which enables ITS to rationally deploy road resources and enhance the utilization efficiency of road networks. Improvements in prediction performance are evident by utilizing synchronized rather than stepwise components to model spatial-temporal correlations. Some existing studies have designed graph structures containing spatial and temporal attributes to achieve spatial-temporal synchronous learning. However, two challenges remain due to the intricate dynamics: (a) Accounting for the impact of external factors in spatial-temporal synchronous modeling. (b) Multiple perspectives in constructing spatial-temporal synchronous graphs. To address the mentioned limitations, a novel model named dynamic multiple-graph spatial-temporal synchronous aggregation framework (DMSTSAF) for traffic prediction is proposed. Specifically, DMSTSAF utilizes a feature augmentation module (FAM) to adaptively incorporate traffic data with external factors and generate fused features as inputs to subsequent modules. Moreover, DMSTSAF introduces diverse spatial and temporal graphs according to different spatial-temporal relationships. Based on this, two types of spatial-temporal synchronous graphs and the corresponding synchronous aggregation modules are designed to simultaneously extract hidden features from various aspects. Extensive experiments constructed on four real-world datasets indicate that our model improves by 3.68–8.54% compared to the state-of-the-art baseline.

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Haskew, T. A., H. P. Stern e Zuojun Chen. "Efficient dynamic synchronous machine simulation with harmonics". IEEE Transactions on Energy Conversion 11, n. 2 (giugno 1996): 298–304. http://dx.doi.org/10.1109/60.507181.

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Langheim, F. J. P., A. C. Leuthold e A. P. Georgopoulos. "Synchronous dynamic brain networks revealed by magnetoencephalography". Proceedings of the National Academy of Sciences 103, n. 2 (30 dicembre 2005): 455–59. http://dx.doi.org/10.1073/pnas.0509623102.

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Jager, Cornelius, Iossif Grinbaum e Jasmin Smajic. "Dynamic Short-Circuit Analysis of Synchronous Machines". IEEE Transactions on Magnetics 53, n. 6 (giugno 2017): 1–4. http://dx.doi.org/10.1109/tmag.2017.2661580.

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Bahi, Jacques, Raphaël Couturier e Flavien Vernier. "Synchronous distributed load balancing on dynamic networks". Journal of Parallel and Distributed Computing 65, n. 11 (novembre 2005): 1397–405. http://dx.doi.org/10.1016/j.jpdc.2005.05.007.

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Liu, Xintian, Yucai Li, Yao He, Xinxin Zheng e Guojian Zeng. "VIRTUAL SYNCHRONOUS MOTOR DYNAMIC POWER DECOUPLING STRATEGY". Progress In Electromagnetics Research C 90 (2019): 209–24. http://dx.doi.org/10.2528/pierc18102504.

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Martens, O. "Precise synchronous detectors with improved dynamic reserve". IEEE Transactions on Instrumentation and Measurement 49, n. 5 (2000): 1046–49. http://dx.doi.org/10.1109/19.872928.

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Chlebus, B. S., K. Diks e A. Pelc. "Broadcasting in synchronous networks with dynamic faults". Networks 27, n. 4 (luglio 1996): 309–18. http://dx.doi.org/10.1002/(sici)1097-0037(199607)27:4<309::aid-net5>3.0.co;2-k.

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Friston, Karl J. "The labile brain. I. Neuronal transients and nonlinear coupling". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 355, n. 1394 (29 febbraio 2000): 215–36. http://dx.doi.org/10.1098/rstb.2000.0560.

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In this, the first of three papers, the nature of, and motivation for, neuronal transients is described in relation to characterizing brain dynamics. This paper deals with some basic aspects of neuronal dynamics, interactions, coupling and implicit neuronal codes. The second paper develops neuronal transients and nonlinear coupling in the context of dynamic instability and complexity, and suggests that instability or lability is necessary for adaptive self–organization. The final paper addresses the role of neuronal transients through information theory and the emergence of spatio–temporal receptive fields and functional specialization. By considering the brain as an ensemble of connected dynamic systems one can show that a sufficient description of neuronal dynamics comprises neuronal activity at a particular time and its recent history. This history constitutes a neuronal transient. As such, transients represent a fundamental metric of neuronal interactions and, implicitly, a code employed in the functional integration of brain systems. The nature of transients, expressed conjointly in distinct neuronal populations, reflects the underlying coupling among populations. This coupling may be synchronous (and possibly oscillatory) or asynchronous. A critical distinction between synchronous and asynchronous coupling is that the former is essentially linear and the latter is nonlinear. The nonlinear nature of asynchronous coupling enables the rich, context–sensitive interactions that characterize real brain dynamics, suggesting that it plays a role in functional integration that may be as important as synchronous interactions. The distinction between linear and nonlinear coupling has fundamental implications for the analysis and characterization of neuronal interactions, most of which are predicated on linear (synchronous) coupling (e.g. crosscorrelograms and coherence). Using neuromagnetic data it is shown that nonlinear (asynchronous) coupling is, in fact, more abundant and can be more significant than synchronous coupling.

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Lindsey, B. G., Y. M. Hernandez, K. F. Morris, R. Shannon e G. L. Gerstein. "Dynamic reconfiguration of brain stem neural assemblies: respiratory phase-dependent synchrony versus modulation of firing rates". Journal of Neurophysiology 67, n. 4 (1 aprile 1992): 923–30. http://dx.doi.org/10.1152/jn.1992.67.4.923.

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1. The objective of this work was to determine whether configurations of midline brain stem neural assemblies change during the respiratory cycle. 2. Spike trains of several single neurons were recorded simultaneously in anesthetized, paralyzed, bilaterally vagotomized, artificially ventilated cats. Data were analyzed with cross-correlational and gravity methods. 3. Sequential samples from each of eight groups of neurons known to contain synchronously discharging neurons exhibited temporal variations in that synchrony. 4. Gravity analysis of short (less than 200-s) samples of spike train data revealed 20 pairs of clustered particles that were not predicted from cross-correlation analysis of the parent data sets (greater than 20 min). 5. Twenty-nine groups of three to eight simultaneously monitored neurons, each with at least two synchronously discharging neurons, were analyzed for evidence of respiratory phase-dependent modulation of that coordinated activity. Spikes from successive interleaved inspiratory and expiratory intervals were analyzed separately. 6. Neurons pairs in 11 groups were more synchronous during the inspiratory interval; six groups had pairs that were more synchronous during the expiratory period. In two groups, different pairs were synchronous in different respiratory phases. In 11 of the 26 pairs that exhibited phase-dependent differences in synchrony, neither neuron had a respiratory-modulated firing rate as judged by either the cycle-triggered histogram or an analysis of variance of their firing rates. 7. Configurations of respiratory-related brain stem neural networks changed with time and the phases of breathing. Neurons with no apparent respiratory modulation of their individual firing rates collectively exhibited respiratory phase-dependent modulation of their impulse synchrony.(ABSTRACT TRUNCATED AT 250 WORDS)

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Long, Yi, e Xiao Jun Yang. "Robust Adaptive Sliding Mode Synchronous Control for a Planar Redundantly Actuated Parallel Manipulator". Advanced Materials Research 605-607 (dicembre 2012): 1583–88. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.1583.

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To obtain better trajectory tracking, a new synchronous control with sliding mode surface is proposed. Based on Kane equation, the dynamics model of a planar 2-DOF redundantly actuated parallel mechanism was formulated. With trajectory contour error, the synchronization error was defined and the sliding surface was determined. After dynamic equation linearization, a robust adaptive sliding mode synchronous controller was designed with stability analysis. After Matlab simulation, figures of tracking errors and synchronization errors changing with time compared with computed torque method were plotted. Results show that the robust adaptive sliding mode synchronous control can be able to achieve good trajectory tracking compared with computed torque controller.

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36

Chenghao, Liu. "RESEARCH OF SPEED SLIDING MODE OBSERVER FOR PERMANENT MAGNET SYNCHRONOUS MOTOR FOR ELECTRIC VEHICLE". EPH - International Journal of Science And Engineering 4, n. 2 (27 giugno 2018): 19–24. http://dx.doi.org/10.53555/eijse.v4i2.164.

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Permanent magnet synchronous motor is the most drive motor of electric cars, to solve the problem of permanent magnet synchronous motor without position sensor speed control system has speed detection delay, error detection, slow dynamic response etc. The speed of sliding mode observer for permanent magnet synchronous motor used in electric vehicles, analyzes the structure and principle of sliding mode observer, combined with the mathematical model of PMSM, the design of electric vehicle speed sliding mode observer for permanent magnet synchronous motor. The simulation speed of sliding mode observer designed by MATLAB, the simulation results show that the speed of sliding mode observer for permanent magnet synchronous motor in electric vehicle design has the advantages of fast detection speed, small detection error, fast dynamic response etc

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37

LU, PINGLI, YING YANG e LIN HUANG. "GLOBAL DYNAMIC PROPERTIES OF A SYNCHRONOUS MACHINE MODEL". International Journal of Bifurcation and Chaos 18, n. 10 (ottobre 2008): 3113–28. http://dx.doi.org/10.1142/s0218127408022287.

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In this paper, rich global dynamical properties are considered for a fundamental synchronous machine model: from global asymptotic stability of trivial equilibrium to chaotic oscillations. Based on Kalman–Yakubovich–Popov (KYP) lemma, static feedback controller is designed such that the synchronous machine model is global asymptotic stable which guarantees that the existence of limit cycles or chaotic oscillations is impossible.

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38

Kim, S. A., J. H. Song, S. W. Han e Y. H. Cho. "An Improved Dynamic Modeling of Permanent Magnet Synchronous Machine with Torque Ripple Characteristics". Journal of Clean Energy Technologies 6, n. 2 (marzo 2018): 117–20. http://dx.doi.org/10.18178/jocet.2018.6.2.445.

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39

Zhu, Hongchao, Jie Zhang e Yin Zhang. "Startup control strategies for pre-fabricated synchronous condensers using static frequency converters". Journal of Physics: Conference Series 2708, n. 1 (1 febbraio 2024): 012012. http://dx.doi.org/10.1088/1742-6596/2708/1/012012.

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Abstract In ultra-high voltage transmission systems, a considerable number of dynamic reactive power compensation devices must be equipped. Synchronous condensers are capable of providing substantial amounts of dynamic reactive power. Therefore, distributed prefabricated synchronous condensers can be deployed in ultra-high voltage transmission systems to supply reactive power support to the power grid. The start-up of synchronous condensers can only be achieved through external means. Currently, there are multiple start-up methods available for small-capacity prefabricated synchronous condensers. With the rapid advancements in frequency conversion technology and power electronics, static frequency converters (SFCs) can be utilized to initiate synchronous condensers. This paper investigates the principles of SFC start-up and coordinated control while also configuring protective devices for SFCs based on their structural characteristics and operational principles. A validation platform consisting of one SFC starting two synchronous condensers was established to analyze their start-up time, yielding results demonstrating the ability of SFC-driven distributed small-capacity synchronous condensers to rapidly adjust the power quality of the power grid.

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40

Xie, Wanying, Xiaoguang Qi, Changsheng Chen, Qianmao Zhang, Jiahui Tian e Liwen Zheng. "Dynamic Aggregation Method of Wind Farms with Virtual Synchronous Generator-Controlled Wind Turbines". Journal of Physics: Conference Series 2401, n. 1 (1 dicembre 2022): 012069. http://dx.doi.org/10.1088/1742-6596/2401/1/012069.

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Abstract The frequency and voltage dynamic processes of each wind turbine in the existing wind farm are different, and the available aggregation model of wind farms mainly focuses on the steady-state output power, lacking an effective dynamic aggregation mechanism. Wind turbines usually adopt the virtual synchronous generator method (VSG) to simulate the external characteristics of the traditional synchronous generator. Its frequency dynamic response is mainly affected by the virtual inertia and damping parameters, and the excitation regulator parameters determine the voltage dynamic response. Therefore, the aggregation method of the traditional synchronous generator is also applicable to such wind turbines. Firstly, the dynamic characteristics of the points of wind farms’ point of common coupling (PCC) are discussed. Then, the dynamic aggregation method of the VSG-wind farms is proposed based on the Kuramoto (KM) model and the small signal analysis of the wind turbines. Finally, a wind farm consisting of multiple VSG-wind turbines under disturbances is simulated in PSCAD/EMTDC to verify the effectiveness of the proposed dynamic aggregation method.

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41

Deshmukh, Ankosh D., Nitesh D. Shambharkar e Prashant M. Gade. "Effect of a Mode of Update on Universality Class for Coupled Logistic Maps: Directed Ising to Ising Class". International Journal of Bifurcation and Chaos 31, n. 03 (15 marzo 2021): 2150042. http://dx.doi.org/10.1142/s0218127421500425.

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Ising model at zero temperature leads to a ferromagnetic state asymptotically. There are two such possible states linked by symmetry, and Glauber–Ising dynamics are employed to reach them. In some stochastic or deterministic dynamical systems, the same absorbing state with [Formula: see text] symmetry is reached. This transition often belongs to the directed Ising (DI) class where dynamic exponents and persistence exponent are different. In asymmetrically coupled sequentially updated logistic maps, the transition belongs to the DI class. We study changes in the nature of transition with an update scheme. Even with the synchronous update, the transition still belongs to the DI class. We also study a synchronous probabilistic update scheme in which each site is updated with the probability [Formula: see text]. The order parameter decays with an exponent [Formula: see text] in this scheme. Nevertheless, the dynamic exponent [Formula: see text] is less than [Formula: see text] even for small values of [Formula: see text] indicating a very slow crossover to the Ising class. However, with a random asynchronous update, we recover [Formula: see text]. In the presence of feedback, synchronous update leads to a transition in the DI universality class which changes to Ising class for synchronous probabilistic update.

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Zhao, Jiaxi, Lin Liu, Tianhe Wang, Xiangzhou Wang, Xiaohui Du, Ruqian Hao, Juanxiu Liu e Jing Zhang. "Synchronous Phase-Shifting Interference for High Precision Phase Imaging of Objects Using Common Optics". Sensors 23, n. 9 (27 aprile 2023): 4339. http://dx.doi.org/10.3390/s23094339.

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Quantitative phase imaging and measurement of surface topography and fluid dynamics for objects, especially for moving objects, is critical in various fields. Although effective, existing synchronous phase-shifting methods may introduce additional phase changes in the light field due to differences in optical paths or need specific optics to implement synchronous phase-shifting, such as the beamsplitter with additional anti-reflective coating and a micro-polarizer array. Therefore, we propose a synchronous phase-shifting method based on the Mach–Zehnder interferometer to tackle these issues in existing methods. The proposed method uses common optics to simultaneously acquire four phase-shifted digital holograms with equal optical paths for object and reference waves. Therefore, it can be used to reconstruct the phase distribution of static and dynamic objects with high precision and high resolution. In the experiment, the theoretical resolution of the proposed system was 1.064 µm while the actual resolution could achieve 1.381 µm, which was confirmed by measuring a phase-only resolution chart. Besides, the dynamic phase imaging of a moving standard object was completed to verify the proposed system’s effectiveness. The experimental results show that our proposed method is suitable and promising in dynamic phase imaging and measurement of moving objects using phase-shifting digital holography.

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43

Shi, Yao Chen, Zhan Guo Li e Dan Liu. "Research on the Tension Effects on Automobile Damping Synchronous Belt Transmission System Damping and Dynamic Stiffness". Applied Mechanics and Materials 687-691 (novembre 2014): 407–10. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.407.

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because of the synchronism belts driving has the advantages of vibration absorption, noise reduction, constant transmission ratio, so it is widely used in automotive engine timing driving system, The stiffness and damping coefficients of the synchronous belt is the main factor affecting the synchronous belt transmission in the process of vibration and noise. In this paper, the model W automotive synchronous belt is simplified as a spring damper system, to solve the stiffness coefficient and damping coefficient of synchronous belt, design of a device for measuring the synchronous belt stiffness coefficient and damping coefficient, measured the belt stiffness coefficient and damping coefficient in the conditions of different tension, and the accuracy of the solution method for synchronous belt stiffness coefficient and damping coefficient was verified as well.

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Elias, Elric, Michael Dyer e Timothy D. Sweeny. "Ensemble Perception of Dynamic Emotional Groups". Psychological Science 28, n. 2 (30 dicembre 2016): 193–203. http://dx.doi.org/10.1177/0956797616678188.

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Crowds of emotional faces are ubiquitous, so much so that the visual system utilizes a specialized mechanism known as ensemble coding to see them. In addition to being proximally close, members of emotional crowds, such as a laughing audience or an angry mob, often behave together. The manner in which crowd members behave—in sync or out of sync—may be critical for understanding their collective affect. Are ensemble mechanisms sensitive to these dynamic properties of groups? Here, observers estimated the average emotion of a crowd of dynamic faces. The members of some crowds changed their expressions synchronously, whereas individuals in other crowds acted asynchronously. Observers perceived the emotion of a synchronous group more precisely than the emotion of an asynchronous crowd or even a single dynamic face. These results demonstrate that ensemble representation is particularly sensitive to coordinated behavior, and they suggest that shared behavior is critical for understanding emotion in groups.

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Ayalur Krishnamoorthy, Parvathy, Kamaraj Vijayarajan e Devanathan Rajagopalan. "Application of Quadratic Linearization for the Control of Permanent Magnet Synchronous Motor". Advances in Power Electronics 2011 (16 novembre 2011): 1–11. http://dx.doi.org/10.1155/2011/273081.

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Many of the existing control methods for the permanent magnet synchronous motor (PMSM) either deal with steady state models or consider dynamic models under particular cases. A dynamic model of the PM machine allows powerful control-theoretic techniques such as linearization to be applied to the system. Existing exact feedback linearization of dynamic model of PMSM suffers from singularity issues. In this paper, we propose a quadratic linearization approach for PMSM based on the approximate linearization technique which does not introduce singularities. A MATLAB simulation is used to verify the effectiveness of the linearization technique proposed. Also, to account for higher-order and unmodelled dynamics of PMSM, tuning of the linearizing transformation is proposed and verified using simulation.

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46

LE VAN QUYEN, MICHEL, HEINZ G. SCHUSTER e FRANCISCO J. VARELA. "FAST DYNAMIC COUPLING FROM SLOW NEURONAL OSCILLATORS". International Journal of Bifurcation and Chaos 06, n. 10 (ottobre 1996): 1807–16. http://dx.doi.org/10.1142/s0218127496001144.

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We focus here on the possible role of the widely distributed slow (4–10 Hz) intrinsic bursting neurons in the establishment of long range spacetime coherent subgroups of neurons at multiple locations. We show that a dynamic coupling of these relaxation oscillators provides a simple mechanism whereby an excitatory interconnected network can give rise to coexisting synchronous assemblies of slow neurons in a phase ordered relationship. In the model, this sequential phase locking is dependent on fast inhibitory feedbacks. As a consequence, global rhythms of a broad frequency range spontaneously arise from the regular succession of synchronous assemblies.

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47

Rader, Nancy de Villiers, e Patricia Zukow-Goldring. "How the hands control attention during early word learning". Gesture and Multimodal Development 10, n. 2-3 (31 dicembre 2010): 202–21. http://dx.doi.org/10.1075/gest.10.2-3.05rad.

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We have proposed that gestures play a significant role in directing infants’ attention during early word learning when caregivers synchronize the saying of a word with a dynamic gesture; this synchronization functions to bring sight and sound together, providing a basis for perceiving them as belonging together (Zukow-Goldring & Rader, 2001). To test this claim, we presented 9–14 month-old infants with videos of speakers using synchronous dynamic vs. static gestures (Study 1) or synchronous dynamic vs. asynchronous dynamic gestures (Study 2) while introducing a novel object. Eye tracking allowed us to measure where infants looked over time during the word–object pairings and during a test for word learning. We hypothesized that dynamic gestures would draw infants’ attention from the mouth to the object, that infants would attend more to the object at the time the word was spoken when the gesture was dynamic and synchronous with speech, and that synchrony of gesture and speech would result in better word learning. These three hypotheses were supported.

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He, Yuling, Mengya Jiang, Kai Sun, Minghao Qiu e David Gerada. "Analysis on Rotor Vibration Characteristics under Dynamic Rotor Interturn Short Circuit Fault in Synchronous Generators". Energies 16, n. 18 (13 settembre 2023): 6585. http://dx.doi.org/10.3390/en16186585.

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A dynamic rotor interturn short circuit fault may occur during synchronous generator operation. However, there is no method to analyze the generator’s characteristics under the dynamic rotor interturn short circuit fault and identify the fault. In order to solve this problem, a new dynamic rotor interturn short circuit fault analysis model is creatively proposed through mathematical derivation. Firstly, the rotor vibration characteristics and the mechanical response under magnetic pull excitation are theoretically analyzed. In addition, a finite element modeling method for the dynamic rotor interturn short circuit fault is proposed, and an experimental device is designed. The model of a synchronous generator under the dynamic rotor interturn short circuit fault is established to obtain the rotor’s unbalanced magnetic pulls and mechanical responses by finite element calculation. Finally, the rotor vibrations are tested on a CS-5 prototype generator. The validity of the model is verified by finite element calculation and an experiment. This paper provides theoretical support for the diagnosis of a synchronous generator’s dynamic rotor interturn short circuit fault.

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Qu, Gang, e Hao Yuan. "Automatic Voltage Control of Large-scale Synchronous Condensers in UHV-DC Converter Station". E3S Web of Conferences 236 (2021): 01001. http://dx.doi.org/10.1051/e3sconf/202123601001.

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Abstract (sommario):

Large-scale synchronous condenser can provide a powerful dynamic reactive power for the Ultra high-voltage (UHV) Direct Current (DC) transmission system. The dynamic characteristics of synchronous condenser ensure the reactive power support capability in the case of grid fault. In this paper, the control strategy and deployment of the synchronous condensers in East China Power Grid are presented. Taking converter station as an example, this paper introduces the main architecture of automatic voltage control (AVC) system, and the relationship between host computers and slave computers. In the substation, it describes the mechanism of several control modes, and designs the on-site test scheme of the control modes. After on-site testing, the correct operation of the large-scale synchronous condensers can be guaranteed.

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Skiba, Rafal M., e Patrik Vuilleumier. "Brain Networks Processing Temporal Information in Dynamic Facial Expressions". Cerebral Cortex 30, n. 11 (25 giugno 2020): 6021–38. http://dx.doi.org/10.1093/cercor/bhaa176.

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Abstract This fMRI study examines the role of local and global motion information in facial movements during exposure to novel dynamic face stimuli. We found that synchronous expressions distinctively engaged medial prefrontal areas in the rostral and caudal sectors of anterior cingulate cortex (r/cACC) extending to inferior supplementary motor areas, as well as motor cortex and bilateral superior frontal gyrus (global temporal-spatial processing). Asynchronous expressions in which one part of the face unfolded before the other activated more the right superior temporal sulcus (STS) and inferior frontal gyrus (local temporal-spatial processing). These differences in temporal dynamics had no effect on visual face-responsive areas. Dynamic causal modeling analysis further showed that processing of asynchronous expression features was associated with a differential information flow, centered on STS, which received direct input from occipital cortex and projected to the amygdala. Moreover, STS and amygdala displayed selective interactions with cACC where the integration of both local and global motion cues could take place. These results provide new evidence for a role of local and global temporal dynamics in emotional expressions, extracted in partly separate brain pathways. Importantly, we show that dynamic expressions with synchronous movement cues may distinctively engage brain areas responsible for motor execution of expressions.

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