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The Metaheuristic Optimization Techniques in Text Classification
No full textMetaheuristic algorithms, inspired by natural phenomena and human-based strategies, offer versatile approaches to navigate diverse search spaces and adapt to dynamic environments. These algorithms, including evolutionary algorithms, swarm intelligence, bio-inspired methods, human-based approaches, and plant-inspired techniques, have found applications across diverse domains such as engineering, finance, healthcare, logistics, and telecommunications. In the text classification domain, metaheuristic techniques have emerged as powerful tools to enhance the accuracy, efficiency, and robustness of classification systems. By optimizing feature subsets, fine-tuning model parameters, and addressing challenges such as feature selection, dimensionality reduction, class imbalance, and noisy data, metaheuristic algorithms provide flexible solutions that adapt to various text datasets and tasks. This review paper comprehensively explores recent advancements in metaheuristic applications in text classification across six categories. From evolutionary-based methods to swarm-based approaches, bio-inspired techniques to physics/chemistry-based strategies, human-based methods to plant-based algorithms, researchers have leveraged diverse metaheuristic techniques to push the boundaries of text classification. Through a systematic analysis of recent research studies, this review provides insights into the strengths, limitations, and future directions of metaheuristic optimization in the context of text classification. © IJCESEN
Investigation of mechanical properties in FFF- produced PLA samples using the Erichsen test: application of definitive screening and RSM
No full textPurpose - This study aims to investigate how printing parameters affect the mechanical properties of specimens produced through fused filament fabrication, using the Erichsen test to assess deformation characteristics and material durability under stress. Design/methodology/approach - Polylactic acid (PLA) specimens were printed and tested in accordance with the ISO 20482 standard. Definitive screening was conducted to identify the most influential process parameters. This study examined the effects of four key process parameters - number of layers, layer height, crossing angle and nozzle diameter - on force, distension, peak energy and energy to break. Each parameter was assessed at three levels and a large number of required experiments was managed by using response surface methodology (RSM). Findings - This study revealed that the number of layers, layer height and crossing angle are the most significant factors that influence the mechanical properties of 3D-printed materials. The number of layers had the greatest impact on the peak force, contributing 44.25%, with thicker layers typically enhancing material strength. The layer height has a significant effect on energy absorption and deformation, with greater layer heights generally improving these properties. Nozzle diameter contributed only 1.10%, making it the least influential factor; however, its impact became more pronounced in interactions with other parameters. Originality/value - This paper presents a comprehensive experimental investigation into the effects of process parameters on the crack strength and behavior of 3D-printed PLA specimens using the RSM method. The documented results can be used to develop optimization models aimed at achieving desired mechanical properties with reduced variation and uncertainty in the final product.Dogbreve;uscedil; University Scientific Research Projects Coordination Unit [2021-22-D1-B02]This work has been supported by Do & gbreve;u & scedil; University Scientific Research Projects Coordination Unit under grant number 2021-22-D1-B02
Dynamic switched crowding-based multi-objective particle swarm optimization algorithm for solving multi-objective AC-DC optimal power flow problem
No full textIn this paper, the multi-objective AC-DC optimal power flow (MO/AC-DC OPF) problem in the presence of renewable energy sources (RESs), flexible AC transmission system (FACTS) devices and multi-terminal direct current (MTDC) systems is introduced for the first time. Conflicting objective functions and the high complexity of the objective and constraint spaces are the main challenges in finding optimal solutions for MO/AC-DC OPF. To overcome these challenges, twelve different versions of the dynamic switched crowding-based multi-objective particle swarm optimization (DSC-MOPSO) algorithm are introduced in this paper. Studies on multimodal optimization problems have shown that all DSC-MOPSO versions have better performance metrics than the MOPSO algorithm. Using the developed DSC-MOPSO and its strong competitors, the Pareto-optimal solution sets of the MO/AC-DC OPF problem are investigated. In these investigations, the performances of the algorithms are tested for the minimization of dual and triple objectives such as fuel cost, voltage level deviation, emission and power loss in a modified IEEE 30-bus power grid. According to the simulation results, the proposed DSC-MOPSO achieved an improvement in fuel cost between 0.02 % and 5.05 % and a reduction in active power loss between 0.44 % and 30.74% compared to its competitors. The Hypervolume (HV) performance metric was used to evaluate the Pareto-front coverage performance of DSC-MOPSO and other optimizers. The results from nine case studies of the MO/AC-DC OPF were statistically analyzed by the Friedman test according to the 1/HV metric. According to the Friedman test results, the rankings of DSC-MOPSO and MOMA are 1.984 and 3.079, respectively, ranking first and second among all competitors. Finally, in this study, feasible solutions for MO/AC-DC OPF problem are identified for the first time and the stability of competitive algorithms in finding these solutions is analyzed for the first time. The success rates and search times of DSC-MOPSO and MOMA algorithms in finding feasible solutions for MO/AC-DC OPF are 91.01 % (30.641 s) and 82.01 % (46.038 s), respectively
Mechanical behavior investigation of fused deposition modeling joints by using different bonding geometry with variable adhesive thickness
No full textPurposeAdhesively bonded joints are used in many fields, especially in the automotive, marine, aviation, defense and outdoor industries. Adhesive bonding offers advantages over traditional mechanical methods, including the ability to join diverse materials, even load distribution and efficient thermal-electrical insulation. This study aims to investigate the mechanical properties of adhesively bonded joints, focusing on adherends produced with auxetic and flat surfaces adhered with varying adhesive thicknesses.Design/methodology/approachThe research uses three-dimensional (3D)-printed materials, polyethylene terephthalate glycol and polylactic acid, and two adhesive types with ductile and brittle properties for single lap joints, analyzing their mechanical performance through tensile testing. The adhesion region of one of these adherends was formed with a flat surface and the other with an auxetic surface. Adhesively bonded joints were produced with 0.2, 0.3 and 0.4 mm bonding thickness.FindingsResults reveal that auxetic adherends exhibit higher strength compared to flat surfaces. Interestingly, the strength of ductile adhesives in auxetic bonded joints increases with adhesive thickness, while brittle adhesive strength decreases with thicker auxetic bonds. Moreover, the auxetic structure displays reduced elongation under comparable force.Originality/valueThe findings emphasize the intricate interplay between adhesive type, bonded surface configuration of adherend and bonding thickness, crucial for understanding the mechanical behavior of adhesively bonded joints in the context of 3D-printed materials.Dogus University Scientific Research Projects Coordination Unit [2021-22-D1-B02]This work was supported by Dogus University Scientific Research Projects Coordination Unit under grant number 2021-22-D1-B02
A comparative analysis of printing parameter effects of tensile and flexural specimens produced with two different printers by the TAGUCHI method
No full textFused deposition modeling (FDM), a prominent AM technique, involves the layer-by-layer deposition of material to construct objects. Various design and production process parameters influence the mechanical properties of FDM-printed components. This study aims to analyze and compare the impacts of printing parameters, specifically nozzle diameter, layer height, and printing speed, on the tensile and flexural properties of 3D-printed parts utilizing two distinct 3D printers. Polylactic acid (PLA) filament material was employed, and the printing parameters were determined based on prior research findings on mechanical properties. The temperature distribution of the printers was analyzed using a thermal camera during the production process. The Taguchi method was applied to ascertain the optimal parameter levels, and subsequently, an analysis of variance (ANOVA) was executed to evaluate the significance of each parameter. Tensile and flexural tests were conducted on the printed samples, followed by an in-depth analysis of the results. The printer's structure has little effect on temperature distribution, but its impact on sample strength is uncertain. The results revealed that the printing parameters influenced the mechanical properties of the printed parts in different ways in the two unique printers. Printing speed was the most influential parameter for the Ender 3 V2, while layer height had the highest impact on the Ultimaker 2 + . The nozzle diameter also played a significant role in both printers. Visual analysis of the printed samples showed the printing parameters' effects on the printed lines' bonding and quality. This study provides insights into the effects of nozzle diameter, layer height, and printing speed on the tensile and flexural properties of the printed samples. The results contribute to understanding how different printers may require specific parameter settings to achieve optimal performance. Further research is recommended to explore additional parameters and materials, considering particular applications and their requirements.Dogus University Scientific Research Projects Coordination Unit [2021-22-D1-B02]This work has been supported by Dogus University Scientific Research Projects Coordination Unit under grant number 2021-22-D1-B0
Religious governance and political evolution: A historical analysis of Turkey's Diyanet in shaping state-religion relations
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Development and validation of the metaverse perception scale for nursing students
No full textBackground: The use of Metaverse applications in nursing education is increasing every day and the evaluation of nursing students' perceptions of this new digital technology may guide interventions related to the use of the Metaverse. However, currently, no standardized instrument specifically designed to measure nursing students' perceptions of the Metaverse exists in Turkey. Aim: To develop and validate the Metaverse Perception Scale for Turkish nursing students. Method: This methodological study was carried out between March 1, 2023 and June 30, 2023 and its sample consisted of 770 nursing students who were enrolled in undergraduate nursing departments of universities in Turkey. The item pool was created based on a literature review and data were analyzed using descriptive statistics, item analysis, exploratory and confirmatory factor analysis, convergent and divergent validity, correlation analysis, internal consistency reliability and test-retest analysis. Results: The content validity index for the items ranged between 0.85 - 1.00. According to exploratory factor analysis, the eigenvalue of four factors was greater than one. These four factors explained 77.28 % of the total variance. In the scale model developed for this study, model fit was found to be acceptable for goodness of fit index:.921 and root mean square error of approximation:.064. chi 2/sd: 1.659, normalized fit index:.961 and chisquare/degree of freedom revealed that model fit was at a good level and within the recommended value ranges. It was determined that the scale showed convergent and divergent validity and Cronbach's Alpha value ranged between 0.95 and 0.93 in the subscales. The Metaverse Perception Scale in Nursing Students was found to have a high level of test-retest reliability. Conclusion: This study showed that the scale, which consists of 24 items and four subscales, is a valid and reliable measurement tool that can be used to assess nursing students' perceptions of the Metaverse in the Turkish context. This scale can contribute to the evaluation of Turkish nursing students' perceptions of the Metaverse, as well as the effective management of processes related to Metaverse practices
The minimalist art movement and the changes observed in brand revisions inspired by the minimalist art movement
No full textLisansüstü Eğitim Enstitüsü, Grafik Ana Sanat DalıMinimalizm akımı, 1960'larda Amerikalı sanat eleştirmenleri tarafından genç sanatçıların ve heykeltıraşların yeni sanat eğilimlerini belirtmek için kullanılmıştır. Kazimir Malevich ve mimar Mies Van Der Rohe ile ilk sinyallerinin atıldığı söylenebilir. Minimalist tasarım, mimarlık, mobilya tasarımı, grafik tasarım, moda ve iç tasarım dâhil olmak üzere çok çeşitli alanlarda gündeme gelmiştir. Minimalizm sanat akımının oluştuğu dönemden günümüz sanatına evrilmesindeki süreçte birçok değişikliğe gidilmiştir ve 1960 yıllarında ortaya çıkmasının ardından doğal biçimini kaybetmiş olsa dahi, günümüzde oluşturulan minimale indirgenme ilkesi devam etmektedir ve ayrıca popüler bir hal alma durumundadır. Bulunduğumuz yüzyılın Minimalizm akımını gündeme getirmesi, kendinden önceki tarihsel süreçte adından söz ettiren birçok sanat akımının da ortaya çıkmasında büyük rol oynayan dönemsel ve kültürel etkenlerin etkisi olmuştur. Çünkü yaşanılan her dönem kendi içerinde farklı kültürel etkiler barındırmaktadır. Günümüz markalarına ve logolarına baktığımızda, görsel kimliklerinin Minimalist bir yaklaşım doğrultusunda tasarlandığını ve bu markların en önemli prensibinin kuvvetli, aynı zamanda dinamik bir sembolik indirgemeye yönelmesinde yatmış olmasıdır. Bu araştırmada, temeli yıllara dayanan minimalizm kavramının tanımı, minimalizmin doğuşu, minimalizm akımının tarihi, minimalizm sanat akımını etkileyen akımlar ve bu akımların öncü sanatçıları, günümüzde minimalizm kavramı, minimalizm bağlamında kurumsal kimlik öğeleri ve marka logolarında zaman içerisinde görülen değişimler incelenmiştir.The Minimalism movement emerged in the 1960s, initially coined by American art critics to denote the new artistic tendencies of young artists and sculptors. It can be said that its first signals were seen with Kazimir Malevich and architect Mies Van Der Rohe. Minimalist design has gained prominence in various fields including architecture, furniture design, graphic design, fashion, and interior design. While many changes have occurred in the process of its evolution from the inception of the Minimalism art movement to contemporary art, and despite losing its natural form since its emergence in the 1960s, the principle of reduction to the minimal continues to persist today and has also become quite popular. The emergence of the Minimalism movement in this century has been influenced by the temporal and cultural factors that played a significant role in the emergence of many art movements that were prominent in the historical process preceding it. This is because every era carries different cultural influences within itself. When we look at today's brands and logos, it's evident that their visual identities are designed with a Minimalist approach, with the most important principle of these brands lying in a strong, yet dynamic symbolic reduction. This article examines the definition of the concept of minimalism, its origins, the history of the minimalist movement, the movements that influenced the minimalist art movement and their pioneering artists, the concept of minimalism today, corporate identity elements in the context of minimalism, and the changes seen in brand logos over time within the framework of minimalism
Modeling of Biomedical Antennas through Forecasting DNN for the Enlarged Bandwidth
No full text17th United Conference on Millemetre Waves and Terahertz Technologies, UCMMT 2024 -- 21 August 2024 through 23 August 2024 -- Palermo -- 203941Recently, wireless medical technologies are growing day-by-day resulting in complex structures and topologies. Hence, advanced methods are required for designing and optimizing biomedical devices subject to high-dimensional parameter space. This paper is devoted to presenting an effective approach for estimating frequency responses of an implanted, multiple-input multiple-output (MIMO) antenna through the deep neural network (DNN) in terms of S11, S12, and total active reflection coefficient (TARC) specifications. This impressive approach aims to facilitate the time-consuming simulations in large multi-frequency bands and concurrently reduce the dependency on the designer's experience. All the process is performed in an automated environment and the proposed method is verified by designing and optimizing an implanted MIMO antenna operating in frequency bands of 4.34-4.61 GHz, and 5.86-6.64 GHz. In this design, the Long Short-Term Memory (LSTM)-based DNN is trained for the frequency band between 3-5.8 GHz, and afterward the constructed DNN is employed for predicting the various antenna specifications for the future bandwidth of 5.8-8 GHz. © 2024 IEEE
Beam-Steering Antenna Technique Using Operational Amplifiers for Sub-6 GHz
No full textA methodology for beam-steering using operational amplifiers (Op-amps) is presented. Continuous steering is required in various advanced applications and its implementation necessitates additional efforts since singularly control of the feeding of the radiators is mandatory for both phase and amplitude. The present work proposes a technique for generating the required sequence of the feeding signal using two Op-amps for each input port. It leads to generating incremental phases with sequential Op-amps without any limitation in the value of the phase differences, controlled by the bias voltage applied to the Op-amps, hence giving rise to a continuous beam-steering capability. The study case consists of a four-stage oscillator designed for creating a sequence of signals with progressive phase shifts between consecutive outputs. The general scheme allows continuous control of the phase differences here applied for generating a uniform, i.e., constant signal magnitude, feeding sequence. This set of signals is then used to feed a four-element microstrip array operating at 1.2 GHz. The effectiveness of the method is validated by numerical simulation of the array performances. Additionally, the low power consumption of active Op-amps, easy implementation, and high sensitivity are characteristics of the presented paradigm