Search

Controlling variable wind speed turbine (VWT) system based on a doubly-fed induction generator (DFIG) is a challenging task. It requires a control law that is both adaptable and robust enough to handle the complex dynamics of the closed control loop system. Sliding mode control (SMC) is a robust control technology that has shown good performance when employed as a passive fault-tolerant control for wind energy systems. To improve the closed control loop of VWT based on DFIG with the aim of improving energy efficiency, even in presence of nonlinearities and a certain range of bounded parametric uncertainties, whether electrically or mechanically, an adaptive passive fault tolerant control (AP-FTC) based on a self-tuning fractional integral sliding mode control law (ST-FISMC) developed from a novel hyperbolic fractional surface is proposed in this paper. ST-FISMC introduces a nonlinear hyperbolic function into the sliding manifold for self-tuning adaptation of control law, while fractional integral of the control law smooths discontinuous sign function to reduce chattering. Additionally, this work introduces an adaptive observer, developed and proved based on a chosen Lyapunov function. This observer is designed to estimate variations in electrical parameters and stator flux, ensuring sensorless decoupling in indirect field-oriented control (SI-FOC) of DFIG. Lyapunov theory is also used to prove stability of states vectors in closed control loop with presence of bounded parameters uncertainties or external disturbances. Simulation results show that the proposed approach offers better performance in capturing optimal wind energy, as well as the ability to regulate active/reactive power and high resilience in presence of occurring parameter uncertainties or external disturbances. [ABSTRACT FROM AUTHOR]

This article presents a proportional-integral sliding mode control (PI-SMC) approach for a two-mass variable speed wind turbine (VSWT) system. Most studies on wind turbines typically focus mainly on the electromagnetic part of the generators, or even on the high-speed part, considering the shaft stiffness as negligible. However, the generator torque is actually driven by the aerodynamic torque, and a two-mass system like the one studied here plays the role of a transmission element for this power. To address this challenge, the problem of low power generation resulting from wind speed variability is tackled by designing a PI-SMC control law, capable of controlling the mechanical turbine model that optimizes power and torque by tracking the maximum power point (MPPT) for rotational speed and aerodynamic power. To validate the developed theoretical results, an application of the wind turbine system is simulated in Matlab/Simulink, for a particular case. The control used is capable of satisfying the dynamic performance of the systems. [ABSTRACT FROM AUTHOR]

The performance of the robotic manipulator is negatively impacted by outside disturbances and uncertain parameters. The system's variables are also highly coupled, complex, and nonlinear, indicating that it is a multi-input, multi- output system. Therefore, it is necessary to develop a controller that can control the variables in the system in order to handle these complications. This work proposes six control structures based on neural networks (NNs) with proportional integral derivative (PID) and fractional-order PID (FOPID) controllers to operate a 2-link rigid robot manipulator (2-LRRM) for trajectory tracking. These are named as set-point-weighted PID (W-PID), set-point weighted FOPID (W-FOPID), recurrent neural network (RNN)-like PID (RNNPID), RNN-like FOPID (RNN-FOPID), NN+PID, and NN+FOPID controllers. The zebra optimization algorithm (ZOA) was used to adjust the parameters of the proposed controllers while reducing the integral-time-square error (ITSE). A new objective function was proposed for tuning to generate controllers with minimal chattering in the control signal. After implementing the proposed controller designs, a comparative robustness study was conducted among these controllers by altering the initial conditions, disturbances, and model uncertainties. The simulation results demonstrate that the NN+FOPID controller has the best trajectory tracking performance with the minimum ITSE and best robustness against changes in the initial states, external disturbances, and parameter uncertainties compared to the other controllers. [ABSTRACT FROM AUTHOR]

Smart agriculture modifies traditional farming practices, and offers innovative approaches to boost production and sustainability by leveraging contemporary technologies. In today's world where technology is everything, these technologies are utilized to streamline regular tasks and procedures in agriculture, one of the largest and most significant industries in every nation. This research paper stands out from existing literature on smart agriculture security by providing a comprehensive analysis and examination of security issues within smart agriculture systems. Divided into three main sections--security analysis, system architecture and design and risk assessment of Cyber-Physical Systems (CPS) applications--the study delves into various elements crucial for smart farming, such as data sources, infrastructure components, communication protocols, and the roles of different stakeholders such as farmers, agricultural scientists and researchers, technology providers, government agencies, consumers and many others. In contrast to earlier research, this work analyzes the resilience of smart agriculture systems using approaches such as threat modeling, penetration testing, and vulnerability assessments. Important discoveries highlight the concerns connected to unsecured communication protocols, possible threats from malevolent actors, and vulnerabilities in IoT devices. Furthermore, the study suggests enhancements for CPS applications, such as strong access controls, intrusion detection systems, and encryption protocols. In addition, risk assessment techniques are applied to prioritize mitigation tactics and detect potential hazards, addressing issues like data breaches, system outages, and automated farming process sabotage. The research sets itself apart even more by presenting a prototype CPS application that makes use of a digital temperature sensor. This application was first created using a Tinkercad simulator and then using actual hardware with Arduino boards. The CPS application's defenses against potential threats and vulnerabilities are strengthened by this integrated approach, which distinguishes this research for its depth and usefulness in the field of smart agriculture security. [ABSTRACT FROM AUTHOR]

The presence of a high ripple in the inductor current of a DC-DC converter in a photovoltaic converter chain leads to a considerable decrease in the energy efficiency of the converter. To solve this problem, we consider a current-mode control and for economic reasons we used a single inductor current sensor with a low-pass filter. The purpose of the low-pass filter is to minimize the effect of ripple in the inductor current by taking only the DC component of the signal at the output of the sensor for tracking the maximum power point. The objective of this paper is therefore to study the stability of the photovoltaic system as a function of the filter frequency while maintaining a good power level. First, we propose a general modeling of the whole system by linearizing the PV around the maximum power point. Floquet theory is used to determine analytically the stability of the overall system. The fourth-order Runge–Kutta method is used to plot bifurcation diagrams and Lyapunov exponents in MATLAB/SIMULINK when the filter frequency varies in a limited range and the ramp amplitude is taken as a control parameter. Secondly, the PSIM software is used to design the device and validate the results obtained in MATLAB/SIMULINK. The results depicted in MATLAB/SIMULINK are in perfect agreement with those obtained in PSIM. We found that not only is the energy level maintained at the maximum power level of 85.17 W, but also that the stability range of the photovoltaic system increased with the value of the filter cut-off frequency. This research offers a wider range of parameters for stability control of photovoltaic systems contrarily to others found in literature. [ABSTRACT FROM AUTHOR]

The Internet and its users are in continual growth. With it grows the number of organized crimes on the Internet and the potential for individuals to carry out illegal activities. These criminals have gained more awareness of private browsing facilities, and many have found a haven in privacy designed browsers that cover up their tracks and shield their nefarious actions. The development of these privacy features has proven to be a challenge for digital forensic investigators. They strive to perform a thorough analysis of web browsers to collect artefacts relating to illegal activity to be presented as evidence to the court of law and used to convict criminals. “Brave” browser is one of the most recent and fastest-growing private browsers that, up to this point, has not been studied in-depth, and its privacy preservation functionality remains unclear. In this paper, we studied Brave’s private browsing mode, examined its privacy-preserving and forensic data acquisition, and outlined the location and type of evidence available through live and post-mortem state analysis. The unique approach taken included a set of experiments that unveiled how the browser functions and showed the appropriate tools that could be utilized to extract leftover artefacts. Analysis of our results showed that despite Brave leaving no traces of browsing activity on the Hard Disk, visited URLs, images, keyword searches, and even cached videos were retrievable from the RAM, which shows that Brave is not entirely private. [ABSTRACT FROM AUTHOR]

Mobile Ad Hoc Networks (MANETs) are an interconnected system of wireless nodes without any central administration, making them more vulnerable to attacks than their wired counterparts. One such attack is the "gray hole" attack, which affects the integrity of the MANET. In this paper we analyse the effectiveness of three MANET protocols: CGSR, TORA, and ZHLS under a grayhole attack. Using the NS2.35 simulator, we study the impact of gray-hole attacks on the aforementioned protocols in terms of performance metrics such as packet delivery ratio, jitter and throughput. The results showed that ZHLS is more robust under a gray hole attack than its counterparts CGSR and TORA. [ABSTRACT FROM AUTHOR]

In this paper, we propose a threat model and a framework for the secure reuse of software. The proposed framework outlines the procedures to follow in order to avoid threats in a simple way. Addressing and resolving security issues from early on is relatively simpler and more cost effective than doing so later, and this is what the framework aims to achieve. [ABSTRACT FROM AUTHOR]

Energy-efficient clustering and routing are well known optimization problems in the study of Wireless Sensor Network (WSN) lifetime extension. In this paper, we propose an intelligent hybrid optimization algorithm based on a Set Cover approach to create clusters, and min-cost max-flow for routing (SCMC) to increase the lifetime of WSNs. In our method we used linear programming (LP) to model the WSN optimization problem. This model considers minimizing the energy for all nodes in each set cover (cluster), and then minimizing the routing energy between the nodes and the base station through intermediate nodes, namely cluster heads. To evaluate the performance of our scheme, extensive simulations were conducted with different scenarios. The results show that the set cover approach combined with the min-cost max-flow algorithm reduces energy consumption and increases the network's lifetime and throughput. [ABSTRACT FROM AUTHOR]

The performance of the robotic manipulator is negatively impacted by outside disturbances and uncertain parameters. The system's variables are also highly coupled, complex, and nonlinear, indicating that it is a multi-input, multi-output system. Therefore, it is necessary to develop a controller that can control the variables in the system in order to handle these complications. This work proposes six control structures based on neural networks (NNs) with proportional integral derivative (PID) and fractional-order PID (FOPID) controllers to operate a 2-link rigid robot manipulator (2-LRRM) for trajectory tracking. These are named as set-point-weighted PID (W-PID), set-point weighted FOPID (W-FOPID), recurrent neural network (RNN)-like PID (RNNPID), RNN-like FOPID (RNN-FOPID), NN+PID, and NN+FOPID controllers. The zebra optimization algorithm (ZOA) was used to adjust the parameters of the proposed controllers while reducing the integral-time-square error (ITSE). A new objective function was proposed for tuning to generate controllers with minimal chattering in the control signal. After implementing the proposed controller designs, a comparative robustness study was conducted among these controllers by altering the initial conditions, disturbances, and model uncertainties. The simulation results demonstrate that the NN+FOPID controller has the best trajectory tracking performance with the minimum ITSE and best robustness against changes in the initial states, external disturbances, and parameter uncertainties compared to the other controllers., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Jasim Mohamed, Oleiwi, Azar and Mahlous.)