http://hdl.handle.net/10174/14410 2026-08-30T08:32:12Z http://hdl.handle.net/10174/42514 Title: Optimization and Numerical Simulation of Cs₂AgSbBr₆-Based Lead-Free Perovskite Solar Cells Using SCAPS-1D Authors: Haque, Md Ekramul; Ahmed, Md Tofael; Tlemçani, Mouhaydine Abstract: Extensive research into lead-free alternatives has been prompted by the toxicological and environmental issues around lead-based perovskite solar cells. The halide double perovskite Cs₂AgSbBr₄ has become a potential absorber material because of its non-toxic composition, good optoelectronic capabilities, and chemical durability [1]. Using the SCAPS-1D platform [2] and the device architecture FTO/ETL/Cs₂AgSbBr₄/HTL/Au, this work provides a thorough numerical modeling and optimization of Cs₂AgSbBr₆-based solar cells. To determine the ideal charge transport configuration, electron transport layers (TiO₂, SnO₂, ZnO, PCBM) and hole transport layers (Spiro-OMeTAD, CuSCN, NiO, MoO₃) are systematically screened to identify the optimal charge transport arrangement. Crucial elements influencing device performance such as absorber layer thickness, defect density, and doping concentration are investigated through parametric optimization. The results reveal that the optimal ETL/HTL combination significantly enhances power conversion efficiency, offering a viable pathway toward high-performance, environmentally friendly perovskite solar cells. 2026-06-11T23:00:00Z http://hdl.handle.net/10174/42513 Title: Different PV Cooling Approaches Leading to Hybrid PVT System Development Authors: Ahmed, Md Tofael; Ali, Md Suruj; Naeema, Ashrafun; Haque, Md Ekramul; Graça, Rui; Rashel, Masud Rana; Tlemçani, Mouhaydine Abstract: Photovoltaic (PV) modules encounter major output losses during generation due to temperature increases resulting decreasing their efficiency. It does not suffer only performance losses but also creates faults, hotpots, cracks and other types of defects in the PV system module. Conventional active cooling systems like water-based, air based, phase change material (PCM) cooling are used to mitigate temperature rise in the PV system, but it requires external energy to deploy, and the recovered heat cannot be used as useful thermal energy. There are different types of photovoltaic thermal collector exists in the literature, but they mostly focus on the thermal energy generation where the improvement of electrical energy generation is significantly ignored [1]. This work discusses different existing cooling strategies and an overview of the development of hybrid PVT system. To identify sensitiveness of the model, different parameters changes impact on the PVT system is also analyzed. The mathematical model based on electrical and thermal model of the PVT system is also established [2]. Maximum power point tracking (MPPT) is an important factor to be considered in the photovoltaic energy generation and efficiency analysis which is also demonstrated for this developed model [3]. Finally, the work demonstrates the motivation of cooling techniques in the PV system leading to the development of hybrid PVT system. 2026-06-11T23:00:00Z http://hdl.handle.net/10174/42512 Title: Machine Learning–Based Transient Stability Assessment of Renewable Energy Integrated Power Systems Authors: Ali, Md Suruj; Ahmed, Md Tofael; Ashrafun, Naeema; Rana, Masud Rana; Chatti, Nizar; Tlemçani, Mouhaydine Abstract: The use of renewable energy sources (RES) in modern inverter-based power systems is rapidly increasing and poses serious challenges to stability due to the reduction of system inertia and the erratic nature of power generation. Conventional time-domain methods are computationally very laborious and too slow for real-time stability assessment, and smart grids require a data-driven model for real-time monitoring of renewable energy. This paper proposes a machine-learning (ML) based method for fast and accurate transient stability assessment of modern power systems, by utilizing python based open-source simulation environment. A model of the IEEE 14-bus test system is modeled using PandaPower, where solar photovoltaic (PV) and wind generators were integrated at different penetration rates such as 20%, 40%, and 60%. The simulations were conducted considering comprehensive disruption scenarios such as line outages, load variations, and generator trips under different levels of renewable energy penetration. To classify stability, voltage magnitude, line loading, and voltage phasis deviation variables are considered as input characteristics. A Random Forest (RF) and Logistic Regression (LR) model is developed, trained and evaluated including metrics of accuracy, recall, precision, and F1-score. The simulation results demonstrate accuracy of the RF and LR models is 100% and 98.3%, respectively. The analysis reveals weak buses are most sensitive to stability degradation. The proposed models allow millisecond predictions that highlight importance of machine learning based on stability monitoring systems. The method provides modern, practical and scalable stability assessment solutions for next generation for inverter dominated smart grids. 2026-06-11T23:00:00Z http://hdl.handle.net/10174/42417 Title: Ancient Quarries on the Estremoz Anticline (Ossa Morena Zone, Portugal): Exploitation, Use and Dispersion of Estremoz Marbles during Roman times Authors: Luis, Lopes; Moreira, Noel; Vilarinho, Gil; Martins, Rúben; Carneiro, André; Kezirian, Francis; Silva, Marcelo; Nogueira, Pedro Abstract: The use of crystalline marbles from Estremoz Anticline, Alentejo (Southern Portugal), and their historical exploitation are documented since the Roman period. While most of the ancient quarries in the area were originally discovered due to the intense mining activity of the 20th century, the remains that still preserved in situ are very scarce, as this recent exploitation has often erased the existing evidence. However, in several of the cases here documented, recent quarrying operations have contrastingly provided and helped preserve these traces of earlier extractive activity. The analysis of aerial photographs, confirmed by a field visit to the area, identifies almost five hundred marble quarrying and exploration sites in the Estremoz Anticline, most of which were opened in the 70s and 90s of the 20th century, while official records show that in the late 80s there were 187 quarries operating simultaneously around the villages of Estremoz, Vila Viçosa and Borba. Today, for various reasons (including the globalisation of the economic market, the ageing of the population, recurring economic crises, the recent tightening of safety regulations, etc.), only around 40 quarries are still active, some of which are over 150 metres deep. Nevertheless, the analysis and conservation of the archaeological evidence of exploration remains a significant challenge. This paper presents a summary and characterisation of the identified ancient quarries and remains in terms of their location, geological setting and marble type, but also of the ancient exploitation methods observed. It also explains the current challenges for the conservation of the relevant geodiversity found and some resulting geoconservation measures, defined according to the site, which could be implemented on a larger scale to conserve and display the unique architectural and cultural heritage of these sites. This study assumes a particular relevance so that both landowners and industry continue to support and preserve this historical and cultural, tangible and intangible heritage of undeniable and differentiating value for this raw material. 2026-06-30T23:00:00Z