Mathematical modeling is very effective method to investigate interaction between insulin and glucose. In this paper, a new mathematical model for insulin-glucose regulation system is introduced based on well-known Lokta-Volterra model. Chaos is a common property in complex biological systems in the previous studies. The results here are in accordance with previous ones and indicating that insulin-glucose regulating system has many dynamics in different situations. The overall result of this paper may be helpful for better understanding of diabetes mellitus regulation system including diseases such as hyperinsulinemia and Type1 DM.
In this paper, image deblurring and denoising are presented. The used images were blurred either with Gaussian or motion blur and corrupted either by Gaussian noise or by salt & pepper noise. In our algorithm, the modified fixed-phase iterative algorithm (MFPIA) is used to reduce the blur. Then a discrete wavelet transform is used to divide the image into two parts. The first part represents the approximation coefficients. While the second part represents the detail coefficients, that a noise is removed by using the BayesShrink wavelet thresholding method.
In this paper, a model of PI-speed control current-driven induction motor based on indirect field oriented control (IFOC) is addressed. To assess the complex dynamics of a system, different dynamical properties, such as stability of equilibrium points, bifurcation diagrams, Lyapunov exponents spectrum, and phase portraits are characterized. It is found that the induction motor model exhibits chaotic behaviors when its parameters fall into a certain region. Small variations of PI parameters and load torque affect the dynamics and stability of this electric machine. A chaotic attractor has been observed and the speed of the motor oscillates chaotically. Numerical simulation results are validating the theoretical analysis.
The dynamic performance of vertical-cavity surface emitting lasers (VCSEL) diodes can be enhanced by incorporating multiquantum-well (MQW) structure in the active region. This paper addresses the transient response of MQW-VCSEL by solving the laser rate equation in the large-signal regime. The analysis makes use of the energy band structure and optical gain spectrum obtained by applying Schrödinger equation to both conduction and valance bands. Simulation results are presented for $1.3~\mu m$ InGaAs/InP VCSEL and indicate clearly that a MQW laser has higher switching speed compared with bulk laser and this finding is more pronounced with small number of wells.
In this paper, a model of PM DC Motor Drive is presented. The nonlinear dynamics of PM DC Motor Drive is discussed. The drive system shows different dynamical behaviors; periodic, quasi-period, and chaotic and are characterized by bifurcation diagrams, time series evolution, and phase portrait. The stabilization of chaos to a fixed point is adopted using slide mode controller (SMC). The chaotic dynamics are suppressed and the fixed point dynamics are observed after the activation of proposed controller. Numerical simulation results show the effectiveness of the proposed method of control for stabilization the chaos and different disturbances in the system.
The aim of this paper is to investigate the switching characteristics of hetrojunction phototransistor (HPT). First, the static characteristics of the HPT are given under ideal conditions to get a physical insight on the main parameters affecting it's response. Then the speed of response of HPT is addressed and supported by simulation results reported for $1.3~\mu m$ InGaAs/InP transistor.
Linearization sensors characteristics becomes very interest field for researchers due to the importance in enhance the system performance, measurement accuracy, system design simplicity (hardware and software), reduce system cost, ..etc. in this paper, two approaches has been introduced in order to linearize the sensor characteristics; first is signal condition circuit based on lock up table (LUT) which this method performed for linearize NTC sensor characteristic. Second is ratiometric measurement equation which this method performed for linearize LVDT sensor characteristic. The proposed methods has been simulated by MATLAB, and then implemented by using Anadigm AN221E04 Field Programmable Analog Array (FPAA) development kit which several experiments performed in order to improve the performance of these approaches.
In light of the widespread usage of power electronics devices, power quality (PQ) has become an increasingly essential factor. Due to nonlinear characteristics, the power electronic devices produce harmonics and consume lag current from the utility. The UPQC is a device that compensates for harmonics and reactive power while also reducing problems related to voltage and current. In this work, a three-phase, three-wire UPQC is suggested to reduce voltage-sag, voltage-swell, voltage and current harmonics. The UPQC is composed of shunt and series Active Power Filters (APFs) that are controlled utilizing the Unit Vector Template Generation (UVTG) technique. Under nonlinear loads, the suggested UPQC system can be improved PQ at the point of common coupling (PCC) in power distribution networks. The simulation results show that UPQC reduces the effect of supply voltage changes and harmonic currents on the power line under nonlinear loads, where the Total Harmonic Distortion (THD) of load voltages and source currents obtained are less than 5%, according to the IEEE-519 standard.
This paper presents a comprehensive analysis for the performance of heterojunction bipolar phototransistor (HPT) as an essential element for optoelectronic switch configurations. The theory of operation of the (HPT) is reviewed. Analytical expressions are drived for transistor current components, optical gain $G_{opt}$ and DC current gain $h_{FE}$ in common emitter configuration. The analysis enables one to study the influence of various structure parameters and incident optical power on the optical gain characteristics of the (HPT). Simulation results are presented for a $1.3~\mu m$ $\text{In}_{0.53}\text{Ga}_{0.47}\text{As}/\text{InP}$ structure.
In this study, the chaotic dynamics observed from a vertical cavity surface emitting lasers (VCSELS) subject to delayed optoelectronic feedback are investigated. The theoretical investigation is performed by using a MATLAB software package. The nonlinear dynamics of a VCSEL are examined using a single mode rate equations model. The key role played by system parameters such as delay time and the feedback strength on laser chaotic dynamics is addressed.
In this paper, three phase induction motor (IM) has been modelled in stationary reference frame and controlled by using direct torque control (DTC) method with constant V/F ratio. The obtained drive system consists of nine nonlinear first order differential equations. The numerical analysis is used to investigate the system behavior due to control parameter change. The integral gain of speed loop is used as bifurcation parameter to test the system dynamics. The simulation results show that the system has period-doubling route to chaos, period-1, period-2, period-4, and then the system gets chaotic oscillation. A specific value of the parameter range shows that the system has very strong randomness and a high degree of disturbance
Recently, chaos theory has been widely used in multimedia and digital communications due to its unique properties that can enhance security, data compression, and signal processing. It plays a significant role in securing digital images and protecting sensitive visual information from unauthorized access, tampering, and interception. In this regard, chaotic signals are used in image encryption to empower the security; that’s because chaotic systems are characterized by their sensitivity to initial conditions, and their unpredictable and seemingly random behavior. In particular, hyper-chaotic systems involve multiple chaotic systems interacting with each other. These systems can introduce more randomness and complexity, leading to stronger encryption techniques. In this paper, Hyper-chaotic Lorenz system is considered to design robust image encryption/ decryption system based on master-slave synchronization. Firstly, the rich dynamic characteristics of this system is studied using analytical and numerical nonlinear analysis tools. Next, the image secure system has been implemented through Field-Programmable Gate Arrays (FPGAs) Zedboard Zynq xc7z020-1clg484 to verify the image encryption/decryption directly on programmable hardware Kit. Numerical simulations, hardware implementation, and cryptanalysis tools are conducted to validate the effectiveness and robustness of the proposed system.
Chaotic Sine-Cosine Algorithms (CSCAs) are new metaheuristic optimization algorithms. However, Chaotic Sine-Cosine Algorithm (CSCAs) are able to manipulate the problems in the standard Sine-Cosine Algorithm (SCA) like, slow convergence rate and falling into local solutions. This manipulation is done by changing the random parameters in the standard Sine-Cosine Algorithm (SCA) with the chaotic sequences. To verify the ability of the Chaotic Sine-Cosine Algorithms (CSCAs) for solving problems with large scale problems. The behaviors of the Chaotic Sine-Cosine Algorithms (CSCAs) were studied under different dimensions 10, 30, 100, and 200. The results show the high quality solutions and the superiority of all Chaotic Sine-Cosine Algorithms (CSCAs) on the standard SCA algorithm for all selecting dimensions. Additionally, different initial values of the chaotic maps are used to study the sensitivity of Chaotic Sine-Cosine Algorithms (CSCAs). The sensitivity test reveals that the initial value 0.7 is the best option for all Chaotic Sine-Cosine Algorithms (CSCAs).
To gain insight into complex biological endocrine glucose-insulin regulatory system where the interactions of components of the metabolic system and time-delay inherent in the biological system give rise to complex dynamics. The modeling has increased interest and importance in physiological research and enhanced the medical treatment protocols. This brief contains a new model using time delay differential equations, which give an accurate result by utilizing two explicit time delays. The bifurcation analysis has been conducted to find the main system parameters bifurcation values and corresponding system behaviors. The results found consistent with the biological experiments results.
In this work, a new flux controlled memristor circuit is presented. It provides a tool to emulate the pinched hysteresis loop. When driven the memristor by a bipolar periodic signal, the memristor exhibits a “pinched hysteresis loop” in the voltage-current plane and starting from some critical frequency, the hysteresis lobe area decreases monotonically as the excitation frequency increases, the pinched hysteresis loop shrinks to a single-valued function when the frequency tends to infinity. The design model numerically simulated and the physical implementation is achieved by using a field programmable analog array (FPAA). The circuit can be modeled and implemented with a changeable nonlinear function blocks and fixed main system blocks. The simplicity of the specific design method makes this proposed model be a very engaging option for the design of the memristor .