Modeling and Simulation of TCSC- Operated Single-Phase Induction Motor

As single-phase induction motor (SPIM) is not a self-starting motor, it has been a common practice to add an auxiliary component to the motor circuit to establish a starting torque. Traditionally, two capacitors are used in SPIM to establish and improve its starting torque and to enhance its running performance. As the Thyristor-Controlled Series Compensator (TCSC) is a control device that considerably alters impedance of the circuit in which it is inserted to be capacitive or inductive, it can be utilized for starting and running purposes in SPIM. This paper explores the representation of the TCSC as a variable impedance and investigates its valuable impacts, when it is operated in its capacitive mode, on the transient behavior of SPIM. It presents a state-space model of the TCSC-inserted SPIM and shows that inserting the TCSC in the auxiliary winding of the SPIM introduces more benefits compared to the traditionally used methods of starting and running the SPIM. The simulation results of the test cases presented in the paper, which include comparisons between the presented approach and the traditional approaches, emphasize that incorporating TCSC with the SPIM brings advantageous features to start and run the motor. The paper will show that controlling the firing angle of the TCSC may attain the desired electromagnetic torque and speed characteristics. The simulation results presented in the paper indicate that the TCSC can effectively replace the traditional auxiliary component and the accompanying mechanical centrifugal switch, which in turn may reduce the size and cost of the SPIM

Gravitational-Search Algorithm for Optimal Controllers Design of Doubly-fed Induction Generator

Recently, the Gravitational-Search Algorithm (GSA) has been presented as a promising physics-inspired stochastic global optimization technique. It takes its derivation and features from laws of gravitation. This paper applies the GSA to design optimal controllers of a nonlinear system consisting of a doubly-fed induction generator (DFIG) driven by a wind turbine. Both the active and the reactive power are controlled and processed through a back-to-back converter. The active power control loop consists of two cascaded proportional integral (PI) controllers. Another PI controller is used to set the q-component of the rotor voltage by compensating the generated reactive power. The GSA is used to simultaneously tune the parameters of the three PI controllers. A time-weighted absolute error (ITAE) is used in the objective function to stabilize the system and increase its damping when subjected to different disturbances. Simulation results will demonstrate that the optimal GSA-based coordinated controllers can efficiently damp system oscillations under severe disturbances. Moreover, simulation results will show that the designed optimal controllers obtained using the GSA perform better than the optimal controllers obtained using two commonly used global optimization techniques, which are the Genetic Algorithm (GA) and Particle Swarm Optimization (PSO)

E-cigarettes Perceptions and Use among Jordanian Medical Students

Purpose: Medical students are the cornerstone for future public health awareness; this study aimed to assess e-cigarettes perceptions and use among medical students.Methods: This is a cross-sectional, questionnaire-based national study. The study included all five medical schools in the country and addressed students in their clinical years. Data were collected through a self-administered and structured paper-based questionnaire between Dec 1, 2018, and Mar 30, 2019. Data obtained were analyzed using IBM SPSS Statistics for Windows and univariate inferential tests were employed to examine differences between groups.Results: A total sample of 1819 (97.4%) students returned their questionnaires; with a declaration of their smoking habits from the five medical schools, 47% are males, and 53% are females. Only 13 students 0.7% of all students or 2.1% of all smokers used e-cigarettes solely, but 177 students 9.5% of all students or 29% of all smokers used e-cigarettes combined with other types of smoking. Most medical students (86%) were aware of e-cigarettes. The main motive behind using e-cigarettes was the rare and different flavors provided by these cigarettes. The general perception among smokers and non-smokers is that e-cigarettes are less harmful and helpful in quitting smoking.Conclusion: Most medical students are aware of e-cigarettes. While their use as the only form of smoking is rare, e-cigarettes are frequently used in combination with other types of smoking

Innovative Energy-Efficient Proxy Re-Encryption for Secure Data Exchange in Wireless Sensor Networks

In the realm of wireless sensor networks (WSNs), preserving data integrity, privacy, and security against cyberthreats is paramount. Proxy re-encryption (PRE) plays a pivotal role in ensuring secure intra-network communication. However, existing PRE solutions encounter persistent challenges, including processing delays due to the transfer of substantial data to the proxy for re-encryption and the computational intensity of asymmetric cryptography. This study introduces an innovative PRE scheme that is meticulously customized for WSNs to enhance the secure communication between nodes within the network and external data server. The proposed PRE scheme optimizes efficiency by integrating lightweight symmetric and asymmetric cryptographic techniques, thereby minimizing computational costs during PRE operations and conserving energy for resource-constrained nodes. In addition, the scheme incorporates sophisticated key management and digital certificates to ensure secure key generation and distribution, which in turn, facilitates seamless authentication and scalable data sharing among the entities in WSN. This scheme maintains sensor-node data encryption and delegates secure re-encryption tasks exclusively to cluster heads, thereby reinforcing data privacy and integrity. Comprehensive evaluations of security, performance, and energy consumption validated the robustness of the scheme. The results confirm that the proposed PRE scheme significantly enhances the security, efficiency, and overall network lifetime of WSNs