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Subject: search.filters.subject.Synchronization

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    On the analysis of a heterogeneous coupled network of memristive Chialvo neurons
    (Springer Nature, 2023-09-01) Ghosh I; Muni SS; Fatoyinbo HO
    We perform a numerical study on the application of electromagnetic flux on a heterogeneous network of Chialvo neurons represented by a ring-star topology. Heterogeneities are realized by introducing additive noise modulations on both the central–peripheral and the peripheral–peripheral coupling links in the topology not only varying in space but also in time. The variation in time is understood by two coupling probabilities, one for the central–peripheral connections and the other for the peripheral–peripheral connections, respectively, that update the network topology with each iteration in time. We have further reported various rich spatiotemporal patterns like two-cluster states, chimera states, coherent, and asynchronized states that arise throughout the network dynamics. We have also investigated the appearance of a special kind of asynchronization behavior called “solitary nodes” that have a wide range of applications pertaining to real-world nervous systems. In order to characterize the behavior of the nodes under the influence of these heterogeneities, we have studied two different metrics called the “cross-correlation coefficient” and the “synchronization error.” Additionally, to capture the statistical property of the network, for example, how complex the system behaves, we have also studied a measure called “sample entropy.” Various two-dimensional color-coded plots are presented in the study to exhibit how these metrics/measures behave with the variation of parameters.
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    An equation-free approach for heterogeneous networks : this dissertation is submitted for the degree of Doctor of Philosophy, School of Mathematical and Computational Sciences, Massey University
    (Massey University, 2023) Zafar, Sidra
    Oscillators exist in many biological, chemical and physical systems. Often when oscillators with different periods of oscillations are coupled, they synchronize and oscillate with the same period. Examples include groups of synchronously flashing fireflies or chirping crickets. There are two questions of interest in this work. (1) Under what conditions will a system of coupled oscillators synchronize? and (2) Can a large system of synchronized oscillators be represented by a smaller number of variables? We study these questions for Kuramoto like models which are coupled in different ways. Examples include spatially extended and all-all coupling. We study conditions under which synchronization occurs in small and large networks by varying the coupling strength, calculating stabilities of synchronized solutions and creating bifurcation diagrams of the steady state solution as a function of coupling strength in one and two-dimensions. We use an equation free approach to approximate the coarse scale behavior of a large, coupled network, for which the equations are known, by a low dimensional description of variables, for which no governing equations are available in closed form. Our results show that a small number of variables can reproduce the behavior of the stable solutions in the full systems. However, the equation-free approach did not work as well for the unstable solutions. Possible reasons for this are explored in the thesis.
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    Web-based asynchronous synchronous environment : a thesis presented in partial fulfilment of the requirements for the degree of Master of Information Science in Computer Science at Massey University
    (Massey University, 2002) Yang, Ang
    In the face of the coming of new information technology era of 21st century, web-based learning has become the major trend of future teaching and learning model. The web-based learning systems are created to simulate the real teaching-learning environment in the classroom using computer software and web-based tools. Learner can study web-based teaching materials according to their individual needs and instructional schedule. Although web-based learning has a lot of advantages over traditional face-to-face learning, the lack of the explanations and interpretation of teaching materials from human teacher in most existing web-based learning system is critical. This project proposed an innovative solution to the problem by combining the benefits of classroom learning in the web-based education. In this project, a prototype Web-based Asynchronous Synchronous Environment (WASE) is developed that not only combines the benefits of tools such as WebCT and AudioGraph, but also integrates lectures given by the human teacher within the system. WASE provides simultaneous low-bandwidth streaming of lecture video and presentation, while facilitating students with presentation annotation facilities, and peer discussion on particular issues related to the topic. The prototype system is built using a three-tier, client-server architecture. The client tier is a set of HTML frames embedded with RealPlayer running in the students' web browsers to provide course contents and navigation guide. The middle tier is an application server which consists of Java Sevlet, JSP engine, and application programs to receive the students' request and send the corresponding course contents and navigation guide information to the client side. The third tier is the relational database for storing the course structure and contents, and for recording the interaction between students and teachers. This project provides a solution where the off-campus students are able to enjoy the explanations and interpretation of course materials from human teacher just as normal on-campus students do in the traditional face-to-face learning environment, while still reaping the benefits of web-based learning.