http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15610 2026-04-23T06:52:36Z 2026-04-23T06:52:36Z YILMAZ, Serdar BİLEN, Mehmet http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15821 2025-09-05T12:12:36Z 2025-01-01T00:00:00Z

EVALUATION OF GRINDING PARAMETERS AND MICROWAVE PRE-TREATMENT ON THE BREAKAGE BEHAVIOR AND ENERGY EFFICIENCY OF COLEMANITE ORE YILMAZ, Serdar; BİLEN, Mehmet This research systematically examined the grindability behavior of colemanite ore by analyzing how variations in mill rotation speed and the geometry of grinding media influence the specific breakage rate. The ore, sourced from the Emet Colemanite Mine, was separated into narrow particle size fractions and subjected to grinding tests at speeds between 65% and 90% of the mill’s critical velocity. Findings indicated that higher rotational speeds resulted in increased specific breakage rates and finer particle size distributions. Moreover, cylindrical media consistently delivered better grinding performance than spherical media across all particle size intervals tested. A predictive model was developed to estimate the specific breakage rate based on particle size, rotation speed, and media shape, and was further validated under various operational conditions. Furthermore, the study examined the impact of microwave pre-treatment on colemanite grindability and energy consumption. Microwave irradiation was applied at 180 W for 5 minutes, resulting in internal thermal stress and microcracking that facilitated improved breakage, particularly in coarser fractions. Bond Work Index (BWI) values decreased by approximately 3–4% following microwave treatment—for instance, from 9.02 kWh/ton to 8.72 kWh/ton for the +3350 µm size fraction. However, the π breakage parameter remained virtually unchanged, at approximately 0.53 for both treated and untreated samples, indicating that the fundamental breakage characteristics of the material were not significantly altered. Although microwave pre-treatment enhanced grindability in specific cases, the total energy requirement for comminution—including both microwave exposure and subsequent grinding— did not demonstrate a substantial reduction. These findings suggest that the energy benefits of microwave-assisted grinding are marginal unless the microwave process itself is optimized for energy efficiency.

2025-01-01T00:00:00Z IŞIK, Ercan http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15820 2025-09-05T12:01:07Z 2025-01-01T00:00:00Z

A STUDY ON STRENGTHENING RC STRUCTURAL ELEMENTS WITH FIBERS-BASED POLYMERS IŞIK, Ercan The structural damage and destruction after the devastating earthquakes bring the importance of the seismic performance of existing structures and the precautions to be taken regarding such structures to the agenda. The different levels of damage and destruction that occurred in reinforced-concrete (RC) structures after the earthquakes reveal that the earthquake performances of these structures are not at a sufficient level. Different reinforcement techniques and materials can be used to increase the seismic performance of existing structures compared to the predicted seismic performance. Insufficient transverse reinforcement used to resist the shear force in RC columns and beams and low concrete strength play a critical role in the damage in these elements. New technologies and advanced materials can be used to increase the earthquake performances of such structural elements. Within the scope of this study, firstly, element-based shear force capacities were obtained for an RC beam and column using steel and aramid fiber materials. In addition, in a selected sample RC structure, steel and aramid fiber was applied only to the columns and the results were compared. The results obtained reveal that these fibers significantly increase the shear force capacity.

2025-01-01T00:00:00Z Ergene, Aysun http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15816 2025-09-05T11:58:00Z 2025-01-01T00:00:00Z

Meta-Analysis of Antibacterial Effects of Silver Nanoparticles (AgNPs) Obtained by Green Synthesis Using Centaurea Species Ergene, Aysun The aim of this study was to compare the antibacterial activity of silver nanoparticles (AgNPs) produced by green synthesis method using extracts from Centaurea species by meta-analysis of articles. We collated data from various studies and used a scientific method to evaluate the efficacy of silver nanoparticles produced using Centaurea species. Meta-analysis allows the data to be interpreted in a broader context and in a statistically significant way, enabling a general evaluation of antibacterial efficacy. A total of three studies were used. These studies provided mean values, standard deviations and sample sizes for Escherichia coli and Staphylococcus aureus bacteria. The effect sizes of the studies were calculated using Cohen's d formula. Heterogeneity analysis, which refers to the consistency between studies, was calculated using Cochran's Q and I² statistics. The results were presented using Forest plots, network graphs and scatter analysis. For this meta-analysis study, we used the Python programming language to analyze and visualize the data.

2025-01-01T00:00:00Z CANIMKURBEY, Betül http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15815 2025-09-04T13:09:10Z 2025-01-01T00:00:00Z

HIGH-PERFORMANCE MDMO-PPV FOR POLYMER-BASED LUMINESCENT SOLAR CONCENTRATORS IN SCALABLE ENERGY HARVESTING CANIMKURBEY, Betül Luminescent solar concentrators (LSCs) have emerged as promising devices for enhancing solar energy harvesting by efficiently capturing and directing light onto photovoltaic cells. Among the diverse luminescent materials investigated, conjugated polymers stand out due to their tunable optical properties, solution-processability, and mechanical flexibility. Poly[2methoxy-5-(3’,7’-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) exhibits a broad absorption spectrum and high photoluminescence quantum yield, exhibited a peak PLQY of 82%, positioning it as a strong candidate to address the limitations of previously studied polymer-based LSCs. Despite its advantageous optoelectronic characteristics, the use of MDMO-PPV in LSCs remains largely underexplored. This study focuses on the fabrication and optical characterization of MDMO-PPV-based LSCs, evaluating their optical efficiency and benchmarking their performance against established polymeric systems. Key challenges in LSC optimization, such as reabsorption losses and limited Stokes shifts, are addressed through potential molecular engineering approaches and photonic design strategies. Optical performance characterization revealed a maximum optical power conversion efficiency of 2.73%, demonstrating significant improvement over previously reported polymer-based LSC systems. By systematically assessing the optical behavior of MDMO-PPV-based LSCs, this work aims to advance the development of high-efficiency, polymer-based LSCs and support their integration into next-generation photovoltaic technologies. The findings are expected to contribute valuable insights into the design of scalable, cost-effective, and efficient luminescent materials for renewable energy applications.

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