In this paper, we present an idea of WiGig-based virtual pass-through (VPT) to acquire the information such as; the number of visitors, nationality, ID number etc. WiGig is a new wireless access standard (IEEE 802.11ad) which works on... more
In this paper, we present an idea of WiGig-based virtual pass-through (VPT) to acquire the information such as; the number of visitors, nationality, ID number etc. WiGig is a new wireless access standard (IEEE 802.11ad) which works on millimeter-wave frequency enabling beam focused high data rate transmission and reception. In the proposed architecture, each visitor is provided a reusable Ultra low power (with battery life of a month or more) identification card (ID) which serves as WiGig client. Two WiGig access points serves as virtual pass-through. These VPTs could be deployed at the desired locations to collect the visitors' information. The collected information is sent to the centralized control room through wireless modem using existing LTE network. This information could be used for counting the number of visitors passing through a specific path and consequently forecasting the number of visitors at the destination. It serves also for a cross-checking and verification of...
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This paper presents a novel algorithm to pick PV-based pumping system operating points that simultaneously achieve maximum delivered power and optimized stability. We present an in-depth analysis of operating point dynamics and shape the... more
This paper presents a novel algorithm to pick PV-based pumping system operating points that simultaneously achieve maximum delivered power and optimized stability. We present an in-depth analysis of operating point dynamics and shape the PV output current and voltage parameter plans. Accordingly, we draw the power bifurcation diagram with all possible operating points. Our proposed algorithm picks the power operating point midway between two consecutive stable points and far enough from the stability boundary to assure system safety. We validated our methodology successfully by numerical simulation based on speculative evidence using MATCON/MATLAB/SimPowerSystems blocks. In addition, we compared the proposed algorithm with P&O MPPT algorithm, and the results verified the reliability of our proposed algorithm to deliver maximum stable power.
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The main purpose of this paper is to give a reasonably comprehensive discussion of what is commonly referred to as the bifurcation analysis applied to an indirect field oriented control of induction machines (IFOC). In the current work,... more
The main purpose of this paper is to give a reasonably comprehensive discussion of what is commonly referred to as the bifurcation analysis applied to an indirect field oriented control of induction machines (IFOC). In the current work, we study the appearance of self-sustained oscillations in AC drives and compute their corresponding stability margins. As the dynamics is explored, a transition mode to chaotic states via codimension one Hopf bifurcations is detected. Based on qualitative approach, investigations of both parametric and phase plane singularities in IFOC induction motor lead to put into evidence equilibrium points and complex oscillatory phenomena such as limit cycles and chaotic behaviors. Furthermore we found out the bifurcation sets and the attraction basins related to such nonlinear phenomena. Bifurcations originated by system and control parameter fluctuations may lead to stability loss. The adequate remedy is to keep the parameters and the state variables inside ...
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In recent years, Energy Efficiency (EE) has become a critical design metric for cellular systems. In order to achieve EE, a fine balance between throughput and fairness must also be ensured. To this end, in this paper we have presented... more
In recent years, Energy Efficiency (EE) has become a critical design metric for cellular systems. In order to achieve EE, a fine balance between throughput and fairness must also be ensured. To this end, in this paper we have presented various resource block (RB) allocation schemes in relay-assisted Long Term Evolution-Advanced (LTE-A) networks. Driven by equal power and Bisection-based Power Allocation (BOPA) algorithm, the Maximum Throughput (MT) and an alternating MT and proportional fairness (PF)-based SAMM (abbreviated with Authors’ names) RB allocation scheme is presented for a single relay. In the case of multiple relays, the dependency of RB and power allocation on relay deployment and users’ association is first addressed through a k-mean clustering approach. Secondly, to reduce the computational cost of RB and power allocation, a two-step neural network (NN) process (SAMM NN) is presented that uses SAMM-based unsupervised learning for RB allocation and BOPA-based supervise...
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A qualitative characterization of the PMSM behavior, based on certain characteristic bifurcation structures is discussed. The equilibrium points of the PMSM were derived from the mathematical model and the stability of the origin... more
A qualitative characterization of the PMSM behavior, based on certain characteristic bifurcation structures is discussed. The equilibrium points of the PMSM were derived from the mathematical model and the stability of the origin equilibrium stability conditions were given. Foliation of the parametric plane and its role to understand the bifurcation mechanisms was illustrated. A particular structure including bifurcations of codimension one and two was identified.
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In this paper we consider a modified model of an Alpazur oscillator with a periodically switching operation. Complex oscillatory phenomena are observed due to both switching operation and the appearance of an additional nonlinear... more
In this paper we consider a modified model of an Alpazur oscillator with a periodically switching operation. Complex oscillatory phenomena are observed due to both switching operation and the appearance of an additional nonlinear component in circuit model. Indeed, subharmonic oscillations and chaotic behavior are illustrated. In addition, time series, phase trajectories and power spectrum was examined in the analysis of the dynamic of system. The transition through doubling period bifurcation cascade to chaos and two other ways of transition to chaotic states are discussed in the state space. For the numerical simulations, techniques for deriving time and composite Poincare method are applied.
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The paper presents a thorough bifurcation analysis of detailed permanent magnet machine with feedback drive, showing the effect of different control and system parameters on the bifurcation and the associated system stability. This study... more
The paper presents a thorough bifurcation analysis of detailed permanent magnet machine with feedback drive, showing the effect of different control and system parameters on the bifurcation and the associated system stability. This study addresses the nonlinear behavior of the PMSM under parametric variation. The analysis of the phase space and parametric singularities are developed in order to identify some specific properties of the PMSM either uncontrolled or under state feedback control. A bifurcation structure of the uncontrolled PMSM in both motor and generator operating modes is identified in the speed-torque chart. The analysis of the complex dynamics of state feedback control of the PMSM permitted to define analytically the bifurcation surfaces of saddle-node (Limit point) and Hopf bifurcations. Seeking broader areas of parametric singularities led to establish the analytical existence conditions of bifurcation manifolds and particularly the bifurcation surfaces. The appearance of intermittent chaotic areas interspersed with cascading bifurcations by doubling the period of limit cycle has been observed in the controlled PMSM. The analysis of the attraction basins in the phase plane, and the synchronization regions in the parametric plane with constant initialization, pave the way to further characterization of the PMSM dynamics with different types of control methods.
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Formulations 3. Analytical Bifurcation Analysis 4. Numerical Simulations 5. Conclusion Acknowledgement References Abstract Analytical determination of the bifurcation thresholds is of important interest for practical electrical machine... more
Formulations 3. Analytical Bifurcation Analysis 4. Numerical Simulations 5. Conclusion Acknowledgement References Abstract Analytical determination of the bifurcation thresholds is of important interest for practical electrical machine design and analysis control. This paper presents mathematical investigation of the qualitative behavior of indirect filed oriented control induction motor based on bifurcation theory. In this context, steady-state responses analysis of the motor model is discussed and an analytical study of generic bifurcations was made. Particular attention is paid to the codimension two bifurcation namely Fold-Hopf bifurcation. The paper introduces some elementary mechanisms of transit from Fold to Fold-Hopf parameter singularity, to derive some analytical rigorous existence conditions and to develop an algorithm for Fold-Hopf bifurcation detection. Some numerical results of equilibrium properties and bifurcation diagrams are then performed to outline our methodology.
Research Interests: Fold and Bifurcation
Analytical determination of the bifurcation thresholds is of important interest for practical electrical machine design and analysis control. This paper presents mathematical investigation of the qualitative behavior of indirect filed... more
Analytical determination of the bifurcation thresholds is of important interest for practical electrical machine design and analysis control. This paper presents mathematical investigation of the qualitative behavior of indirect filed oriented control induction motor based on bifurcation theory. In this context, steady-state responses analysis of the motor model is discussed and an analytical study of generic bifurcations was made. Particular attention is paid to the codimension two bifurcation namely Fold-Hopf bifurcation. The paper introduces some elementary mechanisms of transit from Fold to Fold-Hopf parameter singularity, to derive some analytical rigorous existence conditions and to develop an algorithm for Fold-Hopf bifurcation detection. Some numerical results of equilibrium properties and bifurcation diagrams are then performed to outline our methodology.
Research Interests: Fold and Bifurcation
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Page 1. A Spectral Based Forecasting Tool of Epileptic Seizures Hedi Khammari and Ashraf Anwar College of Computers and Info. Tech., Taif University, Saudi Arabia Abstract A new approach to recognize and predict succedent ...
Analytical determination of the bifurcation thresholds is of important interest for practical electrical machine design and analysis control. This paper presents mathematical investigation of the qualitative behavior of indirect filed... more
Analytical determination of the bifurcation thresholds is of important interest for practical electrical machine design and analysis control. This paper presents mathematical investigation of the qualitative behavior of indirect filed oriented control induction motor based on bifurcation theory. In this context, steady-state responses analysis of the motor model is discussed and an analytical study of generic bifurcations was made. Particular attention is paid to the codimension two bifurcation namely Fold-Hopf bifurcation. The paper introduces some elementary mechanisms of transit from Fold to Fold-Hopf parameter singularity, to derive some analytical rigorous existence conditions and to develop an algorithm for Fold-Hopf bifurcation detection. Some numerical results of equilibrium properties and bifurcation diagrams are then performed to outline our methodology.
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The aim of this paper is to provide numerical analysis to better understand the dynamic behavior of an indirect field oriented control (IFOC) of a current-fed induction motor. Bifurcation analysis of some parameters of the electrical... more
The aim of this paper is to provide numerical analysis to better understand the dynamic behavior of an indirect field oriented control (IFOC) of a current-fed induction motor. Bifurcation analysis of some parameters of the electrical motor model is achived. More importantly, we investigate the change that affects the dynamics and stability under small variations of a Proportional Integral controller (PI) gains. In fact, the dynamical properties of this electrical machine exhibit a rich behaviour. Indeed equilibrium point and complex oscillatory phenomena such as limit cycle and chaos are observed. Since a perturbation of PI control gains led to the existence of regular behavior and region where chaotic phenomena may occur. Thus, a numerical and graphical simulations of both parametric and phase plane singularities are carried out. Using numerical continuation techniques, we compute both bifurcation diagrams for the equilibrium points and the 2-parametric bifurcation curves. The anal...
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A new approach to recognize and predict succedent epileptic seizure by using single channel electroencephalogram (EEG) analysis is proposed. Spectral analysis of a brain time series of the left frontal FP1-F7 (LF) scalp location signal is... more
A new approach to recognize and predict succedent epileptic seizure by using single channel electroencephalogram (EEG) analysis is proposed. Spectral analysis of a brain time series of the left frontal FP1-F7 (LF) scalp location signal is devoted for seizure prediction and analysis. Important findings showing the presence of preictal spectral changes in studied brain signal are described. Spectral features occurring during the preictal epoch are extracted from the application of sliding spectral windows of raw EEG at different moments in time preceding the seizure onset. The same method is then applied to a couple of Intrinsic Mode Functions (IMF1 and IMF2) of the raw EEG (FP1-F7) decomposed by the algorithm of empirical mode decomposition. The main prediction features are derived from the changes of amplitudes, frequency and the number of spikes which are of diagnostic values. The sliding spectral windows were computed to trace the amplitude changes of higher harmonics during time ...
In this paper, we present an energy efficient two-stage hybrid beamforming for the multiuser massive multiple-input multiple-output (MIMO) downlink system. The millimeter wave (mmWave) technology provides high bandwidth but at the same... more
In this paper, we present an energy efficient two-stage hybrid beamforming for the multiuser massive multiple-input multiple-output (MIMO) downlink system. The millimeter wave (mmWave) technology provides high bandwidth but at the same time suffers from high path-, penetration-, and absorption-losses. In massive MIMO system, the large number of antennas at base-station side compensates the mmWave losses but causes high power consumption in the large number of radio frequency (RF) chains. In this paper, we propose a low complexity orthogonal hybrid beamforming (OHBF) design. We use the Householder reflectors generate the orthogonal analog precoding matrix. It reduces the dimension of the digital precoder as well as the inter-user interference in the beam domain. The proposed Householder based OHBF (HOHBF) scheme provides better energy-efficiency (EE) performance than the Gram-Schmidt based hybrid beamforming design in the real-World ill-conditioned massive MIMO channel. It has been s...
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The paper suggests an improved method for diagnosing of transient respiratory disturbances by analyzing the respiratory signals using quadratic time-frequency transformation techniques. Wigner Ville Distribution (WVD) is a good method for... more
The paper suggests an improved method for diagnosing of transient respiratory disturbances by analyzing the respiratory signals using quadratic time-frequency transformation techniques. Wigner Ville Distribution (WVD) is a good method for analyzing nonstationary signals since it gives a good time-frequency resolution compared to many other time-frequency representations. The time marginal of Wigner Ville Distribution can be used for detecting the presence of transient and non-stationary signals. In this work, a crossterm reduced WVD was used for detecting abnormal respiratory disturbances. An adaptive-kernel based ambiguity domain filtering was used to remove the cross-terms in Wigner Ville Distribution. Transient detection algorithms were implemented using cross-term reduced Wigner Ville Distribution and the results were compared with that of Short Time Fourier Transform based methods. The respiratory signals are collected from 5 different test subjects using National Instruments d...
In this paper, a joint spatio–radio frequency resource allocation and hybrid beamforming scheme for the massive multiple-input multiple-output (MIMO) systems is proposed. We consider limited feedback two-stage hybrid beamformimg for... more
In this paper, a joint spatio–radio frequency resource allocation and hybrid beamforming scheme for the massive multiple-input multiple-output (MIMO) systems is proposed. We consider limited feedback two-stage hybrid beamformimg for decomposing the precoding matrix at the base-station. To reduce the channel state information (CSI) feedback of massive MIMO, we utilize the channel covariance-based RF precoding and beam selection. This beam selection process minimizes the inter-group interference. The regularized block diagonalization can mitigate the inter-group interference, but requires substantial overhead feedback. We use channel covariance-based eigenmodes and discrete Fourier transforms (DFT) to reduce the feedback overhead and design a simplified analog precoder. The columns of the analog beamforming matrix are selected based on the users’ grouping performed by the K-mean unsupervised machine learning algorithm. The digital precoder is designed with joint optimization of intra-...
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ABSTRACT—Paroxysmal Atrial Fibrillation (PAF) is the most commonly occurring arrhythmia and its prevalence increases with age. This paper presents an efficient method for detection and prediction of (PAF) using PAF prediction challenge... more
ABSTRACT—Paroxysmal Atrial Fibrillation (PAF) is the most commonly occurring arrhythmia and its prevalence increases with age. This paper presents an efficient method for detection and prediction of (PAF) using PAF prediction challenge database (afpdb) to locate normal person from person who suffers from PAF. We extract 11 features from 100 ECG recorded signals database with the aid of continuous wavelet transform (CWT), to allow accurate extraction of feature from non-stationary signal like ECG, and a Support Vector Machines (SVM) to classify the patterns inherent in the features extracted. We divide the 30-min preceding the PAF into 6 periods with 5-min each. In each suggested period we get the classification result using (SVM). The measured sensitivity, specificity, positive predictivity and accuracy show better and significant results comparable to the other results obtained in the same field in the literature. Index Terms—PAF prediction, ECG signal, continuous wavelet transform...
A new approach to recognize and predict succedent epileptic seizure by using single channel electroencephalogram (EEG) analysis is proposed. Spectral analysis of a brain time series of the left frontal FP1-F7 (LF) scalp location signal is... more
A new approach to recognize and predict succedent epileptic seizure by using single channel electroencephalogram (EEG) analysis is proposed. Spectral analysis of a brain time series of the left frontal FP1-F7 (LF) scalp location signal is devoted for seizure prediction and analysis. Important findings showing the presence of preictal spectral changes in studied brain signal are described. Spectral features occurring during the preictal epoch are extracted from the application of sliding spectral windows of raw EEG at different moments in time preceding the seizure onset. The same method is then applied to a couple of Intrinsic Mode Functions (IMF1 and IMF2) of the raw EEG (FP1-F7) decomposed by the algorithm of empirical mode decomposition. The main prediction features are derived from the changes of amplitudes, frequency and the number of spikes which are of diagnostic values. The sliding spectral windows were computed to trace the amplitude changes of higher harmonics during time ...
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2 ABSTRACT—Paroxysmal Atrial Fibrillation (PAF) is the most commonly occurring arrhythmia and its prevalence increases with age. This paper presents an efficient method for detection and prediction of (PAF) using PAF prediction challenge... more
2 ABSTRACT—Paroxysmal Atrial Fibrillation (PAF) is the most commonly occurring arrhythmia and its prevalence increases with age. This paper presents an efficient method for detection and prediction of (PAF) using PAF prediction challenge database (afpdb) to locate normal person from person who suffers from PAF. We extract 11 features from 100 ECG recorded signals database with the aid of continuous wavelet transform (CWT), to allow accurate extraction of feature from non- stationary signal like ECG, and a Support Vector Machines (SVM) to classify the patterns inherent in the features extracted. We divide the 30-min preceding the PAF into 6 periods with 5-min each. In each suggested period we get the classification result using (SVM). The measured sensitivity, specificity, positive predictivity and accuracy show better and significant results comparable to the other results obtained in the same field in the literature. Index Terms—PAF prediction, ECG signal, continuous wavelet transf...
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Bifurcation theory is the mathematical investigation of changes in the qualitative or topological structure of a studied family. In this paper, we numerically investigate the qualitative behavior of nonlinear RLC circuit excited by... more
Bifurcation theory is the mathematical investigation of changes in the qualitative or topological structure of a studied family. In this paper, we numerically investigate the qualitative behavior of nonlinear RLC circuit excited by sinusoidal voltage source based on the bifurcation analysis. Poincare mapping and bifurcation methods are applied to study both dynamics and qualitative properties of the periodic responses of such oscillator. As numerically illustrated here, a small variation of amplitude or frequency of the driver sinusoidal voltage may involve qualitative changes for witch the system exhibits fold, period doubling and pitchfork bifurcations. In fact, the presence of these kinds of bifurcation necessitates an examination of the role of these singularities in the dynamical behavior of circuit. Particularly, we numerically study the qualitative changes may affect number and stability of the periodic solutions and the shapes of its basins of attraction associated while app...
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In this paper, we present a machine learning based radio resource management (RRM) scheme for a rank-constrained massive multiple-input multiple-output (MIMO) system. We combine the radio resource management and hybrid beamforming design... more
In this paper, we present a machine learning based radio resource management (RRM) scheme for a rank-constrained massive multiple-input multiple-output (MIMO) system. We combine the radio resource management and hybrid beamforming design constraint to desired number of radio frequency (RF) chains. The formulated optimization problem maximizes the sum throughput constraint to total transmit power and the number of RF chains. Being the computationally intensive part of the system, the radio resource allocation in multiuser, multi-carrier massive MIMO system has been replaced by the neural network employing the supervised learning. The proposed design renders the similar sum rate performance given by the CVX-based optimal algorithm, but with 28.72 times less execution time.
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Van der Pol equation submitted to an external driving force gives the bifurcation structure considered in this paper. This structure known as an isoordinal lips cascade is related to the higher harmonic predominance. It is shown that the... more
Van der Pol equation submitted to an external driving force gives the bifurcation structure considered in this paper. This structure known as an isoordinal lips cascade is related to the higher harmonic predominance. It is shown that the study of the higher harmonic predominance in a parameter plane leads to conclude about the existence or non-existence of such a bifurcation structure.
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The existence and the stability of phase space singularities namely equilibrium points and limit cycles are discussed. The coexistence of many stable behaviors for a given set of system parameters and for different initial conditions is... more
The existence and the stability of phase space singularities namely equilibrium points and limit cycles are discussed. The coexistence of many stable behaviors for a given set of system parameters and for different initial conditions is presented putting evidence into the most exciting phenomena in nonlinear dynamics, referred to as multistability. A classical method of speed control of synchronous motor is applied in order to obtain numerical coordinates of equilibrium points. Their stability is analyzed by mean of Eigenvalues derived from Jacobian matrix of the system. The sets of initial conditions leading to such or such equilibrium point known as attraction basins are traced for different sets of system parameters whether that was close or far from critical points or bifurcation.
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Some qualitative properties and bifurcations of periodic responses in a resonant circuit described by a Duffing's equation with a sinusoidal forcing term are investigated. According to the variation of one parameter related to the... more
Some qualitative properties and bifurcations of periodic responses in a resonant circuit described by a Duffing's equation with a sinusoidal forcing term are investigated. According to the variation of one parameter related to the input signal we confirm the correlation between the bifurcation curves and the higher harmonics oscillations such a result has been obtained in former studies for a different circuit and in different parameter plane. The most characteristic phenomenon observed in resonant circuit is the occurrence of tangent bifurcation within a doubling period process. We also identify the Pitchfork bifurcation of 2n/spl pi/-periodic solutions for n>1.
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In this paper, we present an energy-efficient joint machine learning based beam-user selection and low complexity hybrid beamforming for the multiuser massive multiple-input multiple-output (MIMO) downlink system. Massive MIMO system is a... more
In this paper, we present an energy-efficient joint machine learning based beam-user selection and low complexity hybrid beamforming for the multiuser massive multiple-input multiple-output (MIMO) downlink system. Massive MIMO system is a key enabler of 5th generation (5G) technology which is being used in vehicle-to-everything (V2X) communications and other Internet-of-Things (IoT). The large number of antennas at the base-station side causes high power consumption in the radio frequency (RF) chain. Hybrid beamforming techniques are used to reduce the number of RF chains with minimal performance loss. This paper proposes a low complexity orthogonal hybrid beamforming design with the aid of a machine learning based beam-user selection scheme. The Householder (HH) reflectors are used to generate the orthogonal analog beamforming (ABF) matrix. We use a feedforward neural network (FFNN) beam-user selection scheme. The proposed HH ABF+FFNN scheme provides better energy-efficiency (EE) performance in the ill-conditioned massive MIMO channel. It has been shown that the green SE-EE point (41.35b/s/Hz,0.8b/Hz/J) can be obtained by the proposed HH ABF+FFNN scheme as compared to the (33.77b/s/Hz,0.63b/Hz/J) from the state-of-the-art Discrete Fourier transform based techniques.
This paper describes the occurrence of certain dynamic responses of the permanent magnet synchronous motor submitted to a FOC control under a parameter variation. In addition to the transition between limit cycles and equilibrium points... more
This paper describes the occurrence of certain dynamic responses of the permanent magnet synchronous motor submitted to a FOC control under a parameter variation. In addition to the transition between limit cycles and equilibrium points due to the Hopf bifurcation, the multistability property is put into evidence by the identification of several attractors for the same motor and control parameter sets and for different sets of initial conditions. An illustration of the domains or basins of attractions of different attractors is given in a three dimensional phase space. Analytical expressions of equilibrium point coordinates are determined from the differential system equations; their stability can be known from the characteristic polynomial solutions.
Sudden Cardiac Death (SCD) is a major health problem that is responsible for most of all the heart disease deaths. The Ventricular Tachyarrhythmia's (VT's), especially the Ventricular Fibrillation (VF) are the primary cause of the... more
Sudden Cardiac Death (SCD) is a major health problem that is responsible for most of all the heart disease deaths. The Ventricular Tachyarrhythmia's (VT's), especially the Ventricular Fibrillation (VF) are the primary cause of the SCD's. This paper presents a classification method using Support Vector Machine (SVM) algorithm for predicting if there is an SCD occurrence in a signal. This is carried out by comparing certain characteristic features of the ECG signal of a normal healthy person with that of the unhealthy patient prone to SCD. In the time domain, the ECG signal has to be monitored continuously for long hours, which is not feasible and moreover the cardiac arrest in SCD cases occurs for a very short time which is preceded and followed by normal ECG. The noise and some electrical disturbances during measurement also affect the signal feature measurements. So, the signal is transformed into another domain using Wavelet Transformation method (Continuous Wavelet Transform (CWT) to be precise) to extract certain features of the signal and study their pattern while comparing the abnormal ECG signal with that of a normally running ECG signal. The main features that were extracted are the R-peaks, R to R intervals, QRS complexes, QRS complex durations, T-Wave durations and the QT intervals. CWT was used to extract the features information from the ECG signals providing the base. The tests were performed on the data signals taken from the Physionet database [12].
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Some qualitative properties and bifurcations of periodic responses in a resonant circuit described by a Duffing's equation with a sinusoidal forcing term are investigated. According to the variation of one parameter related to the... more
Some qualitative properties and bifurcations of periodic responses in a resonant circuit described by a Duffing's equation with a sinusoidal forcing term are investigated. According to the variation of one parameter related to the input signal we confirm the correlation between the bifurcation curves and the higher harmonics oscillations such a result has been obtained in former studies for a different circuit and in different parameter plane. The most characteristic phenomenon observed in resonant circuit is the occurrence of tangent bifurcation within a doubling period process. We also identify the Pitchfork bifurcation of 2n/spl pi/-periodic solutions for n>1.
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Van der Pol equation submitted to an external driving force gives the bifurcation structure considered in this paper. This structure known as an isoordinal lips cascade is related to the higher harmonic predominance. It is shown that the... more
Van der Pol equation submitted to an external driving force gives the bifurcation structure considered in this paper. This structure known as an isoordinal lips cascade is related to the higher harmonic predominance. It is shown that the study of the higher harmonic predominance in a parameter plane leads to conclude about the existence or non-existence of such a bifurcation structure.
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This paper is Part II of an earlier paper dealing with the numerical study of a two-dimensional nonautonomous ordinary differential equation with a strong cubic nonlinearity, and an external periodical excitation of period τ = 2π/ω... more
This paper is Part II of an earlier paper dealing with the numerical study of a two-dimensional nonautonomous ordinary differential equation with a strong cubic nonlinearity, and an external periodical excitation of period τ = 2π/ω (amplitude E). In the absence of this excitation, this equation of Duffing type does not give rise to self-oscillations. Part I was essentially devoted to analyze the harmonics behavior of period τ solutions, more precisely the behavior of rank-p harmonics according to the points of the parameter plane (ω,E). The present Part II deals with period kτ solutions related to a cascade of closed fold bifurcation curves related to fractional harmonics p/k, k = 3, p = 3,4,…. With respect to the organization of bifurcation curves associated with rank-p harmonics of the basic period τ, this study shows that the situation is a lot more complex for the sequence of bifurcation curves related to rank-p/3 harmonics.
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In this paper, we present a study of stride variations and their dependency on human physical parameters and dynamics. We concentrated on the stride to stride intervals on 50 different subjects. The effects of age, height, weight, length... more
In this paper, we present a study of stride variations and their dependency on human physical parameters and dynamics. We concentrated on the stride to stride intervals on 50 different subjects. The effects of age, height, weight, length of legs and the speed of walking are researched and analyzed against the stride time variations for each subject. It can happen that a subject during the initial and end stages of walking, display some non-uniform stride movements. So, in order to achieve a stable data for analysis, the initial and final samples of stride are truncated. It is understood that the variations in stride at consecutive steps denote instability in walking, which is considered as abnormal in case in adults. In case of children these studies help in assessing the progress in the stability of stride movements as the age progresses. The result of this study can be applied to enhance progress in stride stability by providing adequate feedback to the individuals. For example, f...
This paper includes two main parts: the first part investigates the coexistence and the bifurcation of equilibrium points in the dynamics of permanent magnet sychronous motor (PMSM). Some critical points are detected for a set of system... more
This paper includes two main parts: the first part investigates the coexistence and the bifurcation of equilibrium points in the dynamics of permanent magnet sychronous motor (PMSM). Some critical points are detected for a set of system parameters and initial condition, namely Hopf and saddle Node bifurcations. The second part deals with the synchronization of chaos by using a PI regulator. The role of Largest Lyapunov exponents and their computation are among the main issues discussed in this part.