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With the development of technology, people work hard on image processing and artificial intelligence which require a lot of computer resources. Instead of simply speeding up calculations with processors, people develop the technology of the Cloud with the Internet which performs high‐quality calculations and has quite a huge amount of storage. Thus, in this paper, the authors use a kind of encryption methods, Secure Multi‐Party Computation (SMPC), to protect the important information which is based on the absence of a trusted party and does not use specific keys or methods to maintain the confidentiality of data. Furthermore, the authors also use the error correction, Berlekamp–Welch (BW) algorithm, to double‐check the correction of the information. To apply the two algorithms to image enhancement and convolution neural networks (CNN), the authors will also discuss the homomorphism in all operations, including addition, multiplication, division etc., and find the best way to encrypt and decrypt the information. Finally, the authors will implement the system with cloud computing to decrease the consumption of computer resources and build a system that can do image enhancement and CNN. [ABSTRACT FROM AUTHOR]

The purpose of this research is to develop a high-efficiency, low-cost, and easy-to-use tracking system for vehicles, and it is expected that the system can be extended to areas such as service robots, autonomous driving, and manufacturing. In this paper, we introduced an object detection algorithm based on convolutional neural networks to realize face recognition, which has better efficiency and robustness than traditional machine learning methods. With the concept of edge computing, we deployed the model on the local embedded system to improve the information transmission and security issues of cloud computing. In order to realize the tracking system, this paper builds a mecanum-wheel vehicle with omnidirectional mobility, and proposes a parallel-cascade PID controller architecture based on the mecanum-wheel vehicle. The fixed distance linear tracking control can be realized through the dual-loop feedback control of distance and yaw angle; moreover, the vehicle slipping which is caused by difference rotation speed can be improved. Finally, through algorithm optimization, controller parameter adjustment, and system integration, an omnidirectional mobile vehicle with recognition and tracking functions is realized. The experiment results indicate that the system is stable and robust during actual operation. [ABSTRACT FROM AUTHOR]

A novel technique for transmission of information through visible light communication (VLC) is developed in this study. A light-emitting diode is used as the light source at the transmitting side to send the encrypted information. At the receiving side, a light sensor, OPT-101, is used to receive the light signals that carry the encrypted information. The Arduino Due microcontroller board is used for digital signal processing at both the transmitting and receiving sides. Furthermore, to prevent the transmitted message from being intercepted, two chaotic systems, a master and a slave, with a synchronization controller are designed to obtain the transmitted audio signals. The design enables not only a VLC system with the light transmission path as a straight line (so that data cannot be stolen) but also the encryption of the audio signals with the chaotic system (Rössler system) to enhance data transmission security. The effectiveness of this system is then experimentally verified. [ABSTRACT FROM AUTHOR]

This paper presents a distributed adaptive formation control method for uncertain multiple quadrotor systems under a directed graph that characterizes the interaction among the leader and followers. The proposed approach is based on an adaptive dynamic surface control, consensus algorithm and graph theory, where the system uncertainties are approximately modelled by interval type-2 fuzzy neural networks. The adaptive laws of interval type-2 fuzzy neural network parameters are derived from the stability analysis. In this study, the robust stability of the closed-loop system is guaranteed by the Lyapunov theorem, and the leader-follower formation goal can be asymptotically achieved. The developed control scheme is applied to the followers of quadrotor systems for performance evaluations. Simulation results are also provided to compare with the existing methods and reveal the superiority of the proposed adaptive formation controller. [ABSTRACT FROM AUTHOR]

Abstract Large-eddy simulation (LES) is used to investigate the effect of the spatial arrangement of a utility-scale wind turbine array on the power outputs. Eight turbine-array layouts are considered, where each has 120 turbines installed in 30 rows with aligned or staggered configurations along the wakewise direction. We perform the LESs of neutrally-stratified atmospheric boundary layer over the eight large wind farms with the turbines arranged with a perfectly-aligned configuration, four laterally-staggered configurations, and three vertically-staggered configurations. Unlike the alignment of the turbine micro-siting in the aligned wind farm, both the laterally-staggered and vertically-staggered configurations lead to the misalignment of the turbines with staggered arrangement in the lateral and vertical directions. Simulation results show that the power outputs in the wind farms have obvious decreases to 45–65% within the first 12 turbine rows and retain within that range in the rest. In general, the staggered wind farms produce more power than the aligned wind farm. The laterally-staggered wind farm configurations due to the better adaptability in spatial configuration provide higher power production in the first 6th turbine rows. Moreover, the vertically-staggered configuration causes clear reduction in the maxima of the velocity deficit and the turbulence intensity inside the farm wake flow. Highlights • A validated LES framework is used to quantify the power output in a large wind farm with 120 turbines installed. • Three types of turbine arrays are considered: aligned, laterally-staggered, and vertically-staggered configurations. • The laterally-staggered configuration can promote more power generation in the first 6 turbine rows. • The vertically-staggered configuration leads to clear reduction in the maxima of the velocity deficit and the turbulence intensity. [ABSTRACT FROM AUTHOR]

This paper is concerned with the hybrid synchronization of master-slave Lorenz systems with uncertainties. A new systematic design procedure to synchronize continuous master-slave Lorenz chaotic systems is proposed by using a discrete sliding mode control (DSMC). In contrast to the previous works, the design of DSMC can be simplified and only a single controller is needed to realize chaos synchronization. The proposed DSMC ensures the occurrence of the sliding mode. When the controlled system is in the sliding manifold, the effect of disturbances including matched and unmatched cases are discussed. The proposed results conclude the synchronization error of controlled master-slave systems with matched disturbances can be fully derived to zero or robustly suppressed in an estimated bound even with unmatched disturbances, which is not addressed in the literature. The numerical simulation results demonstrate the success and effectiveness of the proposed DSMC developed in this paper. [ABSTRACT FROM AUTHOR]

The paper presents an improved adaptive sliding mode control method based on fuzzy neural networks for a class of nonlinear systems subjected to input nonlinearity with unknown model dynamics. The control scheme consists of the modified adaptive and the compensation controllers. The modified adaptive controller online approximates the unknown model dynamics and input nonlinearity and then constructs the sliding mode control law, while the compensation controller takes into account the approximation errors and keeps the system robust. Based on Lyapunov stability theorem, the proposed method can guarantee the asymptotic convergence to zero of the tracking error and provide the robust stability for the closed-loop system. In addition, due to the modification in controller design, the singularity problem that usually appears in indirect adaptive control techniques based on fuzzy/neural approximations is completely eliminated. Finally, the simulation results performed on an inverted pendulum system demonstrate the advanced functions and feasibility of the proposed adaptive control approach. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive controller is developed to suppress chaos and track the desired speed in an uncertain chaotic permanent magnet synchronous motor (PMSM) drive system. The controller consists of computational and supervisory control schemes. The computational controller, based on fuzzy neural networks, is used to approximate the unknown nonlinear control signal, while the supervisory controller is employed to attenuate the approximation error effects of the neural network and ensure the system is robust. Simulation results demonstrate that the proposed controller can successfully quash chaotic oscillation in a PMSM and allow speeds to follow the desired trajectory despite the existence of uncertainties. [ABSTRACT FROM PUBLISHER]

Abstract: In this study, the concept of a quasi-sliding mode control (QSMC) is introduced for the robust control of a permanent magnet synchronous motor (PMSM) system subjected to unmatched uncertainties, and even with input nonlinearity. On the basis of the new concept of QSMC, continuous control is obtained, to avoid the chattering phenomenon. As expected, the system state can be stabilized and driven into a predictable neighborhood of zero. Also, this approach only uses a single controller to achieve chaos control, which reduces the cost and complexity of implementation. The results of numerical simulations demonstrate the validity of the proposed QSMC design method. [Copyright &y& Elsevier]

The problem of generalized projective synchronization for unified chaotic systems coupled with sector nonlinear inputs is investigated. Using the sliding mode control technique, a control scheme containing a new proportional–integral switching surface is developed to guarantee generalized projective synchronization even when the uncertainties and sector nonlinearity are present. Numerical simulations are included to demonstrate the effectiveness of the proposed synchronization scheme. [ABSTRACT FROM PUBLISHER]

This paper deals with the H∞ synchronization problem of switched chaotic systems accompanied by a time-driven switching law and its application to secure communications. Based on the Lyapunov stability theory and linear matrix inequality (LMI) and linear matrix equality (LME) optimization techniques, an output feedback controller that guarantees the synchronization of switched master-slave chaotic systems is designed. A chaotic encryption technique that uses synchronization is proposed for securely transmitting a message over public channels. Numerical simulations of both analog and digital security communication systems are conducted to demonstrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

Abstract: A sliding mode control technique is introduced for exponential synchronization of chaotic systems. These systems are described by a general form including matched and unmatched nonlinear functions. A new hitting-free switching surface of proportional–integral type is proposed. This type of switching surface is without the hitting process if the attraction of sliding manifold is ensured. This property makes it easy to exponentially synchronize the master–slave chaotic systems. Based on this switching surface, a robust sliding mode controller (SMC) is derived to guarantee the attraction of sliding manifold even when the system is subjected to input uncertainties. An example is included to illustrate the results developed in this paper. [Copyright &y& Elsevier]

This paper investigates the guaranteed cost control problem of uncertain non-linear systems with time-varying delays via the Takagi-Sugeno fuzzy model approach. Based on the Lyapunov-Krasovskii functional theory and the linear matrix inequality technique, a state feedback controller is proposed to stabilise the non-linear systems and minimise the guaranteed cost of the closed-loop systems. Both delay-dependent and delay-independent stability criteria are derived to guarantee the asymptotic stability of closed-loop systems. Furthermore, the supplementary requirement that the time-derivative of time-varying delays must be smaller than one is released for the proposed delay-dependent stability criterion. Two illustrative examples are provided to verify the validity of the results developed in this paper. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the chaos suppression problem for a class of unified chaotic systems subject to uncertainties and control input with dead-zone nonlinearity. Using the variable structure control technique, a robust adaptive control law is established to suppress chaos in a class of unified chaotic systems even with unknown uncertainties and dead-zone nonlinearity in input. In particular, a switching surface is newly proposed to simplify the task of ensuring the stability of the closed-loop system in the sliding mode. Numerical results validate the effectiveness of the proposed adaptive control scheme. [Copyright &y& Elsevier]

Abstract: This paper investigates the robust chaos suppression problem for some classical Rössler systems using the sliding mode controller (SMC). Based on the proportional-integral (PI) switching surface, a SMC is derived to not only guarantee asymptotical stability of the equilibrium points of the Rössler systems but also reduce the effect of noise perturbation to an -norm performance. The parameter matrix necessary for constructing both PI switching surface and the SMC can be easily solved by the linear matrix inequality (LMI) optimization technique. Finally, two illustrative examples are provided to demonstrate the efficacy of the proposed control methodology. [Copyright &y& Elsevier]

Abstract: This paper investigates the global asymptotic stability (GAS) for a class of nonlinear neural networks with multiple delays. Based on Lyapunov stability theory and the linear matrix inequality (LMI) technique, a less conservative delay-dependent stability criterion is derived. The present result is shown to be less conservative than those given in the literature. [Copyright &y& Elsevier]

Abstract: This article investigates the H ∞ synchronization problem for a general class of chaotic systems. Based on Lyapunov theory, linear matrix inequality (LMI) and linear matrix equality (LME) formulation, the output feedback controller is established to not only guarantee stable synchronization of both master and slave systems but also reduce the effect of external disturbance to an H ∞-norm constraint. Two illustrative examples are provided to demonstrate the effectiveness of the developed theoretical results. [Copyright &y& Elsevier]

Abstract: In this Letter, the globally exponential stability for a class of neural networks including Hopfield neural networks and cellular neural networks with time-varying delays is investigated. Based on the Lyapunov stability method, a novel and less conservative exponential stability condition is derived. The condition is delay-dependent and easily applied only by checking the Hamiltonian matrix with no eigenvalues on the imaginary axis instead of directly solving an algebraic Riccati equation. Furthermore, the exponential stability degree is more easily assigned than those reported in the literature. Some examples are given to demonstrate validity and excellence of the presented stability condition herein. [Copyright &y& Elsevier]

Abstract: This Letter deals with the synchronization problem of a class of neural networks with/without time delays. Based on the drive–response concept and the Lyapunov stability theorem, a delay-independent and decentralized control law is derived to achieve the exponential synchronization. Two illustrative examples are given to demonstrate the effectiveness of the presented synchronization scheme. [Copyright &y& Elsevier]

Presents information on a study which derived a condition related to the existence of an equilibrium point and its global asymptotic stability for cellular neural networks with delay (DCNN). Description of the dynamics of a continuous time DCNN; Global stability of DCNN; Conclusions.

The design and simulation of an analogue integrated circuit for the observer-based synchronization of two chaotic systems and its application to chaotic communication are presented. The chaotic synchronization systems consist of a specially designed drive system and a response. The response system is then designed on the basis of the technique of linear matrix inequality-based state observer design, in which the observer gain is appropriately selected such that the state errors of the drive-response systems asymptotically converge to zero. The proposed observer-based synchronization scheme is then applied to chaotic communication applications, in which the chaotic modulation method is used while the chaotically masked signal and the information are fed back into the transmitter and the former is simultaneously transmitted to the receiver. In addition, the wellknown chaotic Rossler system is considered as an illustrative example, along with its circuit implementation which is also described. Results obtained from PSPICE circuit simulations are given to demonstrate the proposed scheme's effectiveness. [ABSTRACT FROM AUTHOR]

Presents information on a study which developed a systematic approach based on the linear-state-observer design for constructing chaotically synchronized systems. Problem formulation; Chaotic synchronization via linear-state-observer design; Chaotic secure communication via linear-state-observer design; Examples and simulation results; Conclusions.

The paper aims to solve problems of the mathematical modeling and realization of a cube robot capable of self-bouncing and self-balancing. First, the dynamic model of the cube robot is derived by using the conservation of the angular momentum and the torque equilibrium theory. Furthermore, the controllability of the cube robot is analyzed and the angle of the cube robot is derived from the attitude and heading reference system (AHRS). Then the parallel proportional–integral–derivative (PID) controller is proposed for the balancing control of the self-designed cube robot. As for the bounce control of the cube robot, a braking system triggered by the servo motor is designed for converting the kinetic energy to the potential energy. Finally, the experimental results are included to demonstrate that the cube robot can complete the actions of self-bouncing and self-balancing with good robustness to external disturbances. [ABSTRACT FROM AUTHOR]

This paper is concerned with the design of an improved El-Gamal cryptosystem based on chaos synchronization. The El-Gamal cryptosystem is an asymmetric encryption algorithm that must use the public and private keys, respectively, in the encryption and decryption processes. However, in our design, the public key does not have to appear in the public channel. Therefore, this proposed improved El-Gamal cryptosystem becomes a symmetric-like encryption algorithm. First, a discrete sliding mode controller is proposed to ensure the synchronization of master and slave chaotic systems; next, a novel improved El-Gamal cryptosystem is presented. In the traditional El-Gamal cryptosystem, the public key is static and needs to be open which provides an opportunity to attack. However, in this improved design, due to the chaos synchronization, the public key becomes dynamic and does not appear in public channels. As a result, drawbacks of long cipher text and time-consuming calculation in the traditional El-Gamal cryptosystem are all removed. Finally, several performance tests and comparisons have shown the efficiency and security of the proposed algorithm. [ABSTRACT FROM AUTHOR]

In this paper, a new concept of quasi sliding mode control (QSMC) is introduced for the tracking control of chaotic symmetric gyros with linear-plus-cubic damping. In contrast to previous works on sliding mode control, based on the proposed QSMC, the chattering phenomenon can be eliminated. Furthermore, the controlled gyro system can track desired trajectories and tracking errors can be driven into a predictable neighborhood of zero, even when the input nonlinearity is present. Numerical simulations are provided to demonstrate the effectiveness of the proposed QSMC design method. [ABSTRACT FROM PUBLISHER]

This paper is concerned with the parameter identification problem for chaotic systems. An evolutionary programming (EP) approach is newly introduced to solve this problem. The unknown parameters of chaotic systems are taken as a parameter vector, and will be optimally approximated to the exact values of parameters by using the proposed EP algorithm. The unified chaotic systems including Lorenz, Lü and Chen systems are used in an illustrative example to show the validity of the proposed method. [Copyright &y& Elsevier]

Abstract: This paper addresses chaos anti-synchronization of uncertain unified chaotic systems with dead-zone input nonlinearity. Using the sliding mode control technique and Lyapunov stability theory, a proportional–integral (PI) switching surface is proposed to ensure the stability of the closed-loop error system in sliding mode. Then a sliding mode controller (SMC) is proposed to guarantee the hitting of the switching surface even with uncertainties and the control input containing dead-zone nonlinearity. Some simulation results are included to demonstrate the effectiveness and feasibility of the proposed synchronization scheme. [Copyright &y& Elsevier]

Abstract: As well-known, evolutionary programming (EP) algorithms have been considered as promising techniques for global optimal search. The main objective of this paper is to develop a novel EP algorithm for the robust stability analysis of interval neutral delay-differential systems. Two main results are obtained in this paper. First a delay-dependent criterion is derived for ensuring the stability of degenerate neutral time-delay systems, and then by solving some optimization problems, which will be defined later, the robust stability of interval neutral delay-differential systems can be guaranteed. Two numerical examples are given to illustrate the results. [Copyright &y& Elsevier]

Abstract: This study addresses the synchronization of chaotic gyros with unknown parameters and external disturbance via adaptive sliding mode control. To achieve synchronization, a switching surface is adopted such that it becomes easy to ensure the stability of the error dynamics in the sliding mode. Then an adaptive sliding mode controller (ASMC) is derived to guarantee the occurrence of the sliding motion even when the parameters of the drive and response gyros are fully unknown. Numerical simulations are presented to verify that the synchronization can be achieved by using this ASMC. [Copyright &y& Elsevier]

Abstract: This article describes a highly accurate and instant-response ultrasonic system for measuring air temperature using multi-frequency continuous waves (MFCW). The proposed system uses a method heretofore applied only to radio frequency distance measurement but not to air-based ultrasonic systems. The method presented here is based upon the comparative phase shifts generated by three continuous ultrasonic waves of different but closely spaced frequencies. It uses the ultrasonic measurement of the changes in the speed of sound in the air to determine the temperature of bulk air. The changes in the speed of sound are calculated from phase shift of multi-frequency continuous wave. In our experiment, in a temperature-controlled chamber, we placed two 40kHz ultrasonic transducers face to face with a constant distance in between. We use MFCW of 40/41.8/42kHz. A single-chip microprocessor-based signal generator and phase detector are used to record and calculate phase shift and temperature. In a proof-of-concept experiment, it is accurate to ±0.4°C from 0 to 80°C with 0.05% resolution and temperature changes are instantly reflected within 100ms. [Copyright &y& Elsevier]

In this paper we investigate the synchronization problem of drive-response chaotic systems with a scalar coupling signal. By using the scalar transmitted signal from the drive chaotic system, an observer-based response chaotic system with dead-zone nonlinear input is designed. An output feedback control technique is derived to achieve generalized projective synchronization between the drive system and the response system. Furthermore, an adaptive control law is established that guarantees generalized projective synchronization without the knowledge of system nonlinearity, and/or system parameters as well as that of parameters in dead-zone input nonlinearity. Two illustrative examples are given to demonstrate the effectiveness of the proposed synchronization scheme. [ABSTRACT FROM AUTHOR]

In this article, a new single-chip microprocessor-based, non-contact thermometer with high-precision and instant-response is proposed. It uses ultrasonic sensors made of piezoelectric devices to detect changes of the speed of sound in the air and calculate the temperature of the bulk air. The changes of speed of sound are computed from combining two variations, time-of-flight (TOF) from a binary frequency shift-keyed (BFSK) ultrasonic signal and phase shift from two frequency continuous waves (TFCW). This technique can work in a wider range than using phase shift alone and is more accurate than TOF. In our experiment, in a temperature-controlled chamber, we placed two 40 kHz ultrasonic sensors face to face with a fixed distance in between. We use BFSK signals and TFCW of 40 kHz and 42 kHz. A single-chip microprocessor-based signal generator and phase detector are used to record and calculate TOF, phase shift and temperature. The calculated results of temperatures are then sent to either an LCD display or to a PC for calibration and examination. In a proof-of-concept experiment, it is accurate to ±0.3 °C from 0 °C to 60 °C with 0.05% resolution and temperature changes are instantly reflected within 100 ms. The advantages of our system are high accuracy, instant detection, non-contact, low cost and easy implementation. [Copyright &y& Elsevier]

Based on the Halanay inequality lemma, this Letter derives a new sufficient condition for the globally exponential stability of the generalized Cohen–Grossberg neural networks with delays (GDCGNNs). The GDCGNN is quite general, and can describe several well-known neural networks with and without delays, including Hopfield and cellular neural networks. It is shown that the proposed sufficient condition relies on the connection matrices and the network parameters, and that it is independent of the delay parameter. Furthermore, the presented condition is easy to check, and is less restrictive than some of the sufficient conditions proposed in previous studies. The benefits of the developed sufficient condition are demonstrated by comparing its performance in a series of examples with that of several conditions presented previously. [Copyright &y& Elsevier]

Despite many attractive features of an orthogonal frequency-division multiplexing (OFDM) system, the signal detection in an OFDM system over multipath fading channels remains a challenging issue, particularly in a relatively low signal-to-noise ratio (SNR) scenario. This paper presents an iterative synchronization-assisted OFDM signal detection scheme for cognitive radio (CR) applications over multipath channels in low-SNR regions. To detect an OFDM signal, a log-likelihood ratio (LLR) test is employed without additional pilot symbols using a cyclic prefix (CP). Analytical results indicate that the LLR of received samples at a low SNR can be approximated by their log-likelihood (LL) functions, thus allowing us to estimate synchronization parameters for signal detection. The LL function is complex and depends on various parameters, including correlation coefficient, carrier frequency offset (CFO), symbol timing offset, and channel length. Decomposing a synchronization problem into several relatively simple parameter estimation subproblems eliminates a multidimensional grid search. An iterative scheme is also devised to implement a synchronization process. Simulation results confirm the effectiveness of the proposed detector. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, synchronization of Sprott chaotic systems and its application in secure communication are presented. We first utilize a proportional-integral-derivative (PID) control scheme to solve the synchronization problem of chaotic systems. Then for the purpose of application to secure communication, a state signal of the analog chaotic system is converted to a digital train with variable pulse width (square wave with random frequency) by voltage controlled oscillator (VCO). The original digital message is masked by the digital train generated from VCO in the chaotic transmitter via a logical exclusive-OR (XOR) operation and it can be successfully recovered by another VCO and XOR operation at the chaotic receiver due to the synchronization. To verify the system performance, basic electronic components containing operational amplifiers (OPAs), resistors and capacitors are used to implement the proposed PID-based chaotic secure communication system. Finally, the experimental results validate the proposed chaotic communication approach. [Copyright &y& Elsevier]

Abstract: Active queue management (AQM) is a key congestion control scheme for reducing packet loss and improving network utilization in TCP/IP networks. This paper proposes a proportional–integral-derivative (PID) controller as an active queue manager for Internet routers. Due to the limitations of packet-dropping probability and the effects of propagation delays in TCP networks, the TCP AQM network was modeled as a time-delayed system with a saturated input. An improved genetic algorithm is employed to derive optimal or near optimal PID controller gains such that a performance index of integrated-absolute error (IAE) is minimized, and thereby a stable queue length, low packet loss, and high link utilization for TCP networks are guaranteed. The performance of the proposed control scheme is evaluated in various network scenarios via a series of numerical simulations. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to propose an output coupling and feedback scheme, which is not only to guarantee the asymptotic synchronization between the master and the slave chaotic systems with multiple time-delays but also to attenuate the effects of noise perturbation on the overall error system to a prescribed level in terms of the performance index -norm. The output coupling and feedback gain is derived on the basis of the Lyapunov theory and the linear matrix inequality (LMI) technique. Some numerical examples are given to demonstrate the effectiveness of the main results. [Copyright &y& Elsevier]