This work presents a novel and innovative design approach for Graphene Nano-Ribbon Field Effect Transistors (GNR FETs), uniquely employing Zigzag Graphene Nano-Ribbons (ZGNRs) as electrodes and Armchair Graphene Nano-Ribbons (AGNRs) as the channel region. To deeply understand device performance, rigorous first-principles modeling was conducted, leveraging Extended-Hückel formalism alongside Landauer-Buttiker transport theory. Extensive Technology Computer-Aided Design (TCAD) simulations systematically explored the impact of critical parameters such as doping concentration (ND), gate voltage (Vg), and drain voltage (Vd) on transistor behavior. However, the computational intensity associated with such comprehensive analyses necessitated the introduction of an advanced Machine Learning (ML)-assisted methodology, specifically employing a Conventional Artificial Neural Network (C-ANN). Remarkably, this ML-driven strategy achieved highly accurate results within significantly reduced computational times of just 80–90 seconds, underscoring its practicality and efficiency. Furthermore, the intrinsic 2.71 eV band gap of the pristine AGNR channel was effectively modulated in a broad range (0.013–1.6 eV) through controlled doping and engineered defects. An N-passivated AGNR FET demonstrated an extraordinary 157 times enhancement in drive current, although its negligible band gap raised concerns regarding leakage currents. Alternatively, the N-doped Stone-Wales AGNR FET provided a well-balanced performance with a 33.21 nA drive current and a suitable 0.58 eV band gap, substantially reducing leakage risks, enhancing thermal stability, and improving peak inverse voltage robustness. This pioneering ML-assisted C-ANN approach highlights significant potential for accelerating accurate and reliable nano-transistor analyses.

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Coupled oscillations of ring lattices with different types of dielectric resonators are considered. New analytical equations for complex frequencies and amplitudes of resonators, without restrictions on their number, are obtained. General analytical solutions for the frequencies and amplitudes of coupled oscillations for different ring lattices built on different resonators are found. It is noted that the obtained equations are also suitable for describing coupled oscillations of a ring lattices with degenerate oscillations of resonators, as well as with structures that contain ring lattices with different number elements. In general, the solutions for eigen waves propagating in periodic ring structures of DR are found. The solutions for several ring lattices consisting of two, three and four resonators of different types are compared with the numerical values found from the eigenvalues of the general coupling matrix. Good agreement between the analytical and the numerical results of calculating of the coupling matrix eigenvalues is demonstrated. The developed theory is the basis for the design and optimization of parameters of different devices of the microwave, theraherz and optical wavelength ranges, that built on a large number of dielectric resonators of various types. New equations obtained for calculating coupled oscillations of dielectric resonators also allow build more efficient models of scattering for optimization of various dielectric metamaterials.

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Optimal power transmission plays a pivotal role in ensuring the stability and viability of the power grid, and such a need is further exacerbated by the rising power demands that developing power grids face. In this paper, a novel approach is presented to implement the Hippopotamus Optimization Algorithm (HOA) to ensure optimal Thyristor-Controlled Series Capacitor (TCSC) placement and size to reduce power transmission losses and improve voltage profile. A Newton-Raphson load flow study is developed to incorporate TCSC models, aiming to reduce active power losses and costs of generation. The results obtained on the IEEE 14-bus test network indicate the effectiveness of the proposed HOA method over the existing and manual methods. On the IEEE 14-bus test system, the proposed method was effective in reducing active power loss substantially from 13.599 MW to 4.101 MW and lowering the costs of the systems from $6799 to $2788. On the Nigerian 28-bus power grid, the HOA method successfully reduced the active power loss to 732.05 MW, compared to the value of 802.37 MW of active power loss on the base case. It was also successful in lowering the reactive power loss to 1655.58 Mvar, and the cost of operation was reduced to $372,541, outperforming the results obtained through the manual method. These results indicate that the HOA is a powerful strategy that can be employed to reduce active power loss substantially and improve the voltage stability without the need to develop extensive infrastructure.

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This paper presents a comprehensive analysis of the Load Frequency Control (LFC) framework required for the synchronization of Electric Power Systems (EPSs) with Continental Europe (CE). The study focuses on ensuring stable and reliable operation of autonomously functioning EPSs by examining technical requirements and prequalification procedures for Frequency Containment Reserve (FCR) and LFC-related reserves. Numerical simulations were performed to assess system dynamic behavior under disturbance conditions. The results indicate that following a 100 MW active power loss, system frequency decreased to 49.82 Hz and was restored to the nominal 50 Hz within 9 min using FCR and automatic Frequency Restoration Reserve (aFRR). A more severe 200 MW disturbance resulted in a minimum frequency of 49.68 Hz, requiring additional activation of manual Frequency Restoration Reserve (mFRR), with recovery achieved in 18 minutes. In extreme scenarios involving up to 600 MW power loss, the frequency dropped below the critical threshold of 49.2 Hz, but full restoration was achieved within 36 min through coordinated activation of FCR, aFRR, mFRR, and Replacement Reserve (RR). Long-term simulations demonstrated that the Frequency Restoration Control Error (FRCE) remained within the System Operation Guidelines (SOGL) Level 1 limit for 75% of the time and within the stricter Level 2 limit for 96%, meeting CE quality requirements. The study also evaluates prequalification procedures, including technical testing, communication validation, and energy management for Limited Energy Reservoir providers, ensuring robust and non-discriminatory participation in balancing markets.

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