فهرست مقالات Lyapunov Exponent

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  1 - Chaotic dynamic analysis and nonlinear control of blood glucose regulation system in type 1 diabetic patients
  Saeid Khajehvand Seyed Mahdi Abtahi
  In this paper, chaotic dynamic and nonlinear control in a glucose-insulin system in types I diabetic patients and a healthy person have been investigated. Chaotic analysis methods of the blood glucose system include Lyapunov exponent and power spectral density based on چکیده کامل

  In this paper, chaotic dynamic and nonlinear control in a glucose-insulin system in types I diabetic patients and a healthy person have been investigated. Chaotic analysis methods of the blood glucose system include Lyapunov exponent and power spectral density based on the time series derived from the clinical data. Wolf's algorithm is used to calculate the Lyapunov exponent, which positive values of the Lyapunov exponent mean the dynamical system is chaotic. Also, a wide range in frequency spectrum based on the power spectral density is also used to confirm the chaotic behavior. In order to control the chaotic system and reach the desired level of a healthy person's glucose, a novel fuzzy high-order sliding mode control method has been proposed. Thus, in the control algorithm of the high-order sliding mode controller, all of the control gains computed by the fuzzy inference system accurately. Then the novel control algorithm is applied to the Bergman's mathematical model that is verified using the clinical data set. In this system, the control input is the amount of insulin injected into the body and the control output is the amount of blood glucose level at any moment. The simulation results of the closed-loop system in various conditions, along with the performance of the control system in disturbance presence, indicate the proper functioning of this controller at the settling time, overshoot and the control inputs. پرونده مقاله
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  2 - Impulsive Control of Attitude Satellite With Quaternion ‎Parameters
  M. R. Niknam N. Abdi Sobouhi
  10.30495/ijim.2022.58349.1481
  This article uses impulsive control along with quaternion parameters instead of Euler angles in kinematics equations of satellite. ‎The quaternion parameters are applied to overcome singularity problem in the numerical solution. ‎It is assumed that the satellite چکیده کامل

  This article uses impulsive control along with quaternion parameters instead of Euler angles in kinematics equations of satellite. ‎The quaternion parameters are applied to overcome singularity problem in the numerical solution. ‎It is assumed that the satellite is subjected to deterministic external perturbations. ‎At first, ‎the chaotic behavior of system is investigated when there is no control on the system. ‎Then, ‎impulsive control is used to stabilize the satellite attitude around the equilibrium point of origin. ‎Finally, ‎simulation results are given to visualize the effectiveness and feasibility of the proposed ‎method. پرونده مقاله
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  3 - Three-axis optimal control of satellite attitude based on Ponteryagin maximum ‎principle‎
  M. R. Niknam K. Kheiri A. Heydari
  A long time ago, since the launch of the first artificial satellite in 1957, controling attitude of satellites has been considered by the designers and engineers of aerospace industry. Considering the importance of this issue various methods of control in response to th چکیده کامل

  A long time ago, since the launch of the first artificial satellite in 1957, controling attitude of satellites has been considered by the designers and engineers of aerospace industry. Considering the importance of this issue various methods of control in response to this need have been presented and analyzed until now. In this paper, we propose and analyze a three-axis optimal control on the six-dimensional system which describes the kinetic and kinematic equations of a satellite subjected to deterministic external perturbations which induce chaotic motion. At first, the chaotic behavior of system using Lyapunov exponents (LE) and numerical simulations is investigated when no control is affected. Then, a three-axis optimal control is presented by the Pontryagin maximum principle (PMP). This optimal control stabilizes the satellite attitude around the equilibrium point of origin. Finally, we give some simulation results to visualize the effectiveness and feasibility of the proposed ‎method.‎ پرونده مقاله
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  4 - امکان تشخیص آریتمی‌های قلبی با استفاده از تحلیل شاخص‌های آشوبی سیگنال ECG
  علی تمیزی محمد عطایی محمدرضا یزدچی
  سیگنال الکتروکاردیوگرام (ECG) معمول‌ترین روش غیرتهاجمی برای بررسی سلامتی قلب یا تشخیص احتمالی بیماری‌های قلبی است. مطالعات نشان می‌دهد سیگنال ECG یک ساختار خطی ساده ندارد بلکه دارای مؤلفه‌های غیرخطی است. در این مقاله سیگنال ECG به عنوان یک سری زمانی در نظر گرفته شده است چکیده کامل

  سیگنال الکتروکاردیوگرام (ECG) معمول‌ترین روش غیرتهاجمی برای بررسی سلامتی قلب یا تشخیص احتمالی بیماری‌های قلبی است. مطالعات نشان می‌دهد سیگنال ECG یک ساختار خطی ساده ندارد بلکه دارای مؤلفه‌های غیرخطی است. در این مقاله سیگنال ECG به عنوان یک سری زمانی در نظر گرفته شده است و شاخص‌های غیرخطی آشوبی مانند بزرگ‌ترین نمای لیاپانوف ( ) و بعد همبستگی (D2) از سیگنال ECG برای افراد سالم و بیمار استخراج می‌شود. در این راستا الگوریتم‌های مناسب جهت استخراج پارامترهای لازم برای بازسازی فضای حالت و نیز محاسبه بزرگ‌ترین نمای لیاپانوف و بعد همبستگی از روی سیگنال ECG با ملاحظات مربوطه ارائه می‌گردد. سپس با استفاده از طبقه‌بندی کننده فازی امکان تفکیک افراد سالم و بیمار، براساس شاخص‌های آشوبی محاسبه شده بررسی می‌شود. داده‌ها از پایگاه داده‌های MIT-BIH گرفته شده است و مقایسه نتایج برای سه گروه شامل افراد با ریتم قلبی سالم (NSR)، بیماران فیبریلاسیون دهلیزی (AF) و بیماران انسداد دسته شاخه چپ (LBBB) انجام شده است که مبیّن کارایی طبقه‌بندی ارائه شده بر اساس شاخص‌های آشوبی است. پرونده مقاله
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  5 - Analysis of chaotic vibration in a hexagonal centrifugal governor system
  مصطفی غیور سعید ضیایی راد حبیب رمضان نژاد آزاربنی
  In this paper, the periodic, quasi periodic and chaotic responses of rotational machines with a hexagonal centrifugal governor are studied. The external disturbance is assumed as a sinusoid effect. By using the forth order Rung-Kutta numerical integration method, bifurc چکیده کامل

  In this paper, the periodic, quasi periodic and chaotic responses of rotational machines with a hexagonal centrifugal governor are studied. The external disturbance is assumed as a sinusoid effect. By using the forth order Rung-Kutta numerical integration method, bifurcation diagram, largest Lyapunov exponent and Lyapunov dimension are calculated and presented to detect the critical controlling parameter. Having known the critical values, phase portrait, Poincare maps, time history and power spectrum are presented to observe periodic, quasi-periodic and chaotic behaviors of the system. Finally, the system damping is used as a parameter to control chaos. It is shown that by increasing the system damping, the chaotic behavior of the system converts to a periodic motion. پرونده مقاله