scholarly journals Synchronization of Coupled Different Chaotic FitzHugh-Nagumo Neurons with Unknown Parameters under Communication-Direction-Dependent Coupling

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Muhammad Iqbal ◽  
Muhammad Rehan ◽  
Abdul Khaliq ◽  
Saeed-ur- Rehman ◽  
Keum-Shik Hong
Keyword(s):  
Gap Junctions ◽  
Chaotic Behavior ◽  
Coupled System ◽  
Parametric Estimation ◽  
Unknown Parameters ◽  
Estimation Errors ◽  
System A ◽  
Control Scheme ◽  
Control Methodology ◽  
The Impact

This paper investigates the chaotic behavior and synchronization of two different coupled chaotic FitzHugh-Nagumo (FHN) neurons with unknown parameters under external electrical stimulation (EES). The coupled FHN neurons of different parameters admit unidirectional and bidirectional gap junctions in the medium between them. Dynamical properties, such as the increase in synchronization error as a consequence of the deviation of neuronal parameters for unlike neurons, the effect of difference in coupling strengths caused by the unidirectional gap junctions, and the impact of large time-delay due to separation of neurons, are studied in exploring the behavior of the coupled system. A novel integral-based nonlinear adaptive control scheme, to cope with the infeasibility of the recovery variable, for synchronization of two coupled delayed chaotic FHN neurons of different and unknown parameters under uncertain EES is derived. Further, to guarantee robust synchronization of different neurons against disturbances, the proposed control methodology is modified to achieve the uniformly ultimately bounded synchronization. The parametric estimation errors can be reduced by selecting suitable control parameters. The effectiveness of the proposed control scheme is illustrated via numerical simulations.

scholarly journals Communication-Less Frequency Support from Offshore Wind Farms Connected to HVdc via Diode Rectifiers

2020 ◽  
Author(s):  
Oscar Saborío-Romano ◽  
Ali Bidadfar ◽  
Jayachandra Naidu Sakamuri ◽  
Lorenzo Zeni ◽  
Ömer Göksu ◽  
...  
Keyword(s):  
Wind Farms ◽  
Sensitivity Study ◽  
Offshore Wind ◽  
Voltage Measurement ◽  
Estimation Errors ◽  
Offshore Wind Farms ◽  
Direct Voltage ◽  
Control Scheme ◽  
Static Performance ◽  
The Impact

Before diode rectifier (DR) technology for connecting offshore wind farms (OWFs) to HVdc is deployed, in-depth studies are needed to assess the actual capabilities of DR-connected OWFs to contribute to the secure operation of the networks linked to them. This study assesses the capability of such an OWF to provide communication-less frequency support (CLFS) to an onshore ac network. It is shown that the HVdc link’s offshore terminal direct voltage can be estimated from measurements at the OWF’s point of connection with the DR platform. Two different methods are proposed for implementing CLFS in the OWF active power controls. In Method 1, the estimated offshore terminal direct voltage is used for estimating the onshore frequency deviation. In Method 2, the actual offshore terminal direct voltage measurement is used instead. Unique features of the provision of CLFS from OWFs connected to HVdc via DRs are highlighted, and the dynamic and static performance of the CLFS control scheme is compared to that of the communication-based frequency support scheme. To assess the impact of parameter estimation errors on the provision of CLFS, a parametric sensitivity study is presented as well, and recommendations are given to increase accuracy.<br><br>The manuscript has been accepted for publication in IEEE Transactions on Sustainable Energy.

scholarly journals Anti-Synchronization of a Class of Chaotic Systems with Application to Lorenz System: A Unified Analysis of the Integer Order and Fractional Order

Mathematics ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 559 ◽  
Author(s):  
Liang Chen ◽  
Chengdai Huang ◽  
Haidong Liu ◽  
Yonghui Xia
Keyword(s):  
Fractional Order ◽  
Chaotic System ◽  
Finite Time ◽  
Chaotic Systems ◽  
Lorenz System ◽  
Unknown Parameters ◽  
Integer Order ◽  
System A ◽  
Control Scheme ◽  
Lorenz Chaotic System

The paper proves a unified analysis for finite-time anti-synchronization of a class of integer-order and fractional-order chaotic systems. We establish an effective controller to ensure that the chaotic system with unknown parameters achieves anti-synchronization in finite time under our controller. Then, we apply our results to the integer-order and fractional-order Lorenz system, respectively. Finally, numerical simulations are presented to show the feasibility of the proposed control scheme. At the same time, through the numerical simulation results, it is show that for the Lorenz chaotic system, when the order is greater, the more quickly is anti-synchronization achieved.

scholarly journals Communication-Less Frequency Support from Offshore Wind Farms Connected to HVdc via Diode Rectifiers

2020 ◽  
Author(s):  
Oscar Saborío-Romano ◽  
Ali Bidadfar ◽  
Jayachandra Naidu Sakamuri ◽  
Lorenzo Zeni ◽  
Ömer Göksu ◽  
...  
Keyword(s):  
Wind Farms ◽  
Sensitivity Study ◽  
Offshore Wind ◽  
Voltage Measurement ◽  
Estimation Errors ◽  
Offshore Wind Farms ◽  
Direct Voltage ◽  
Control Scheme ◽  
Static Performance ◽  
The Impact

Before diode rectifier (DR) technology for connecting offshore wind farms (OWFs) to HVdc is deployed, in-depth studies are needed to assess the actual capabilities of DR-connected OWFs to contribute to the secure operation of the networks linked to them. This study assesses the capability of such an OWF to provide communication-less frequency support (CLFS) to an onshore ac network. It is shown that the HVdc link’s offshore terminal direct voltage can be estimated from measurements at the OWF’s point of connection with the DR platform. Two different methods are proposed for implementing CLFS in the OWF active power controls. In Method 1, the estimated offshore terminal direct voltage is used for estimating the onshore frequency deviation. In Method 2, the actual offshore terminal direct voltage measurement is used instead. Unique features of the provision of CLFS from OWFs connected to HVdc via DRs are highlighted, and the dynamic and static performance of the CLFS control scheme is compared to that of the communication-based frequency support scheme. To assess the impact of parameter estimation errors on the provision of CLFS, a parametric sensitivity study is presented as well, and recommendations are given to increase accuracy.<br><br>The manuscript has been accepted for publication in IEEE Transactions on Sustainable Energy.

scholarly journals Communication-Less Frequency Support from Offshore Wind Farms Connected to HVdc via Diode Rectifiers

2019 ◽  
Author(s):  
Oscar Saborío-Romano ◽  
Ali Bidadfar ◽  
Jayachandra Naidu Sakamuri ◽  
Lorenzo Zeni ◽  
Ömer Göksu ◽  
...  
Keyword(s):  
Wind Farms ◽  
Sensitivity Study ◽  
Offshore Wind ◽  
Voltage Measurement ◽  
Estimation Errors ◽  
Offshore Wind Farms ◽  
Direct Voltage ◽  
Control Scheme ◽  
Static Performance ◽  
The Impact

Before diode rectifier (DR) technology for connecting offshore wind farms (OWFs) to HVdc is deployed, in-depth studies are needed to assess the actual capabilities of DR-connected OWFs to contribute to the secure operation of the networks linked to them. This study assesses the capability of such an OWF to provide communication-less frequency support (CLFS) to an onshore ac network. It is shown that the HVdc link’s offshore terminal direct voltage can be estimated from measurements at the OWF’s point of connection with the DR platform. Two different methods are proposed for implementing CLFS in the OWF active power controls. In Method 1, the estimated offshore terminal direct voltage is used for estimating the onshore frequency deviation. In Method 2, the actual offshore terminal direct voltage measurement is used instead. Unique features of the provision of CLFS from OWFs connected to HVdc via DRs are highlighted, and the dynamic and static performance of the CLFS control scheme is compared to that of the communication-based frequency support scheme. To assess the impact of parameter estimation errors on the provision of CLFS, a parametric sensitivity study is presented as well, and recommendations are given to increase accuracy.<br><br>The manuscript has been submitted to IEEE Transactions on Sustainable Energy.

Adaptive robust disturbance compensating control for a servo system in the presence of both friction and deadzone

2016 ◽  
Vol 231 (3) ◽  
pp. 432-445 ◽  
Author(s):  
Jinho Jung ◽  
Donghyuk Lee ◽  
Jong Shik Kim ◽  
Seong Ik Han
Keyword(s):  
Robust Control ◽  
Control Method ◽  
Servo System ◽  
Friction Model ◽  
Adaptive Robust Control ◽  
Estimation Errors ◽  
Control Scheme ◽  
Adaptive Laws ◽  
Control Methodology ◽  
Funnel Control

An adaptive robust control that does not need sophisticated plant modeling work is proposed for precise output positioning of a servo system in the presence of both friction and deadzone nonlinearities. It is difficult to achieve effective motion control by traditional linear control methodology for these types of nonlinearities, without the aid of a proper compensation scheme for nonlinearity. In this study, dynamic friction is modeled by a Tustin friction model, and inverse deadzone method is adopted to compensate deadzone effect. The adaptive laws of the unknown system dynamic parameters, friction and deadzone, are derived. Furthermore, a robust control method with funnel control is proposed to compensate for unmodeled and estimation errors. The boundedness and convergence of the closed-loop system are ensured by a Lyapunov stability analysis. The performance of the proposed control scheme is verified through experiments on the XY table servo system and the robotic manipulator.

scholarly journals Immersion and Invariance Adaptive Control for Spacecraft Pose Tracking via Dual Quaternions

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Xiaoping Shi ◽  
Xuan Peng ◽  
Yupeng Gong
Keyword(s):  
Relative Motion ◽  
Direction Cosine ◽  
Dual Quaternion ◽  
Unknown Parameters ◽  
Estimation Errors ◽  
Performance Improvements ◽  
Pose Tracking ◽  
Immersion And Invariance ◽  
Dual Quaternions ◽  
Control Scheme

This paper addresses the simultaneous attitude and position tracking of a target spacecraft in the presence of general unknown bounded disturbances in the framework of dual quaternions, which provides a concise and integrated description of the coupled rotational and translational motions. By virtue of the newly introduced dual direction cosine matrix, the dimension of the dual quaternion-based relative motion dynamics written in vector/matrix form can be lowered to six. Treating the disturbances as unknown parameters, a modular adaptive pose tracking control scheme composed of two separately designed parts is then derived. One part is the adaptive disturbance estimator designed based on the immersion and invariance theory. Driven by the disturbance estimation errors, it can realize exponential convergence of the estimations and has the nice “parameter lock” property, which can hardly be expected in the conventional certainty equivalent adaptive controllers. The other part is a proportional-derivative-like pose tracking controller where the estimated disturbances are directly used. The closed-loop stability of the relative motion system under different kinds of disturbances is proven by Lyapunov stability analysis. Simulations and comparisons with two previous dual quaternion-based controllers demonstrate the novel features and performance improvements of the proposed control scheme.

Technology and Hospital Information System: A Case of Implementation of Electronic Clinical Records in Hospital Maternity Irene Neto in Lubango, Angola

2019 ◽  
Vol 10 (11) ◽  
pp. 1131-1135
Author(s):  
Tomas Hambili Paulo Sanjuluca ◽  
◽  
Ricardo Correia ◽  
Anabela Antunes de Almeida ◽  
Ana Gloria Diaz Martinez ◽  
...  
Keyword(s):  
Maternity Hospital ◽  
Management Support ◽  
Retrospective Case ◽  
System A ◽  
Clinical Records ◽  
Retrospective Case Study ◽  
The Impact ◽  
And Child Health

Introduction: In order to have a good assessment of the quality of maternal and child health care, it is essential that there is up-to-date and reliable information. Objective: To evaluate the impact of the implementation of a computerized database of clinical processes in the admission, archive and medical statistics section, of Maternity hospital Irene Neto/Lubango-Angola. Methodology: A descriptive study with a quantitative and qualitative approach to carry out a retrospective case study deliveries and newborns, records from 2014 to 2017. Final considerations: The implementation of this project may contribute to the improvement of clinical management support management of the hospital as well as facilitating access to information for research and scientific production.

The Impact of Political Transition on Ghana’s Educational System. A Case Study of the 4th Republic

2018 ◽  
Author(s):  
Emmanuel Owusu-Kwarteng ◽  
Prince Opoku ◽  
Gershon Dagba ◽  
Mark Amankwa
Keyword(s):  
Educational System ◽  
Political Transition ◽  
System A ◽  
The Impact
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