DSpace@ATÜ (Adana Alparslan Türkeş Bilim ve Teknoloji Universiti)
Not a member yet
3463 research outputs found
Sort by
Modified all-GaN multidevice interleaved boost converter topology for hybrid electrical vehicles and its miniaturization
No full textIn inverter technology for hybrid and electric vehicles, some properties, such as low weight, compactness, small size, high power density, and high efficiency, are highly required because they affect vehicle production costs and fuel economy. Bringing reliable and cheap devices with high response rates into being, which is in close relation with circuit design, miniaturization, and appropriate selection of components, have become one of the main topics of scientific research in electronics. One of the main obstacles to achieving these goals is the bulkiness of inductors and capacitors. These essential building blocks of the converter topology are used to reduce input current and output voltage ripples, which are closely related to thermal stress in batteries, affecting their lifespan. This study proposes a GaN-based multidevice interleaved boost converter (MDIBC) topology for hybrid vehicles. The topology is investigated in terms of power loss, efficiency, current and voltage ripples, and size of passive components under two salient case studies at various switching frequencies. In both cases, current and voltage are reduced by smaller values of passive components without sacrificing efficiency. Efficiencies ranging between 97.34 and 97.83%, are achieved with passive components remaining in the benchmark converter
Shock response of sandwich panels with additively manufactured polymer gyroid lattice cores
No full textThis work evaluates the shock response of sandwich structures with gyroid lattice cores made from Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS), and Thermoplastic Polyurethane (TPU) using shock tube experiments coupled with high-speed photography and digital image correlation (DIC). The study found that gyroid lattice structures exhibit high energy absorption capacity and good structural integrity under shock loading, making them suitable for high strength-to-weight ratio and energy absorption applications in aerospace and defense industries. The sandwich panel with a TPU-core structure exhibited the highest deformation under shock loading, with a maximum deflection of approximately 6 mm, followed by ABS at 0.9 mm and PLA at 0.82 mm. Under shock loading, the sandwich panel with TPU gyroid core exhibited the highest specific deformation energy (0.146 J/g), which is consistent with its flexibility, though it remained in the same general order as ABS (0.104 J/g) and PLA (0.070 J/g). Interestingly, the specific total energy of the TPU gyroid core sandwich, while the lowest at 39.310 J/g, was still relatively close to ABS (54.098 J/g) and PLA (52.620 J/g), despite the substantial difference in inherent stiffness of TPU compared to ABS and PLA. This suggests that while TPU's stiffness is much lower compared to PLA and ABS, its total energy absorption capability in gyroid form is not as drastically reduced, indicating the importance of geometry and mass distribution within the gyroid structure. Overall, the results of this study highlight the importance of careful design and optimization of these structures to utilize their unique properties fully
A Comparative Study on the Estimation of Wind Speed and Wind Power Density Using Statistical Distribution Approaches and Artificial Neural Network-Based Hybrid Techniques in Çanakkale, Türkiye
No full textIn recent years, wind energy has become remarkably popular among renewable energy sources due to its low installation costs and easy maintenance. Having high energy potential is of great importance in the selection of regions where wind energy investments will be made. In this study, the wind power potential in canakkale Province, located in the northwest of Turkiye, is examined, and the wind speed is estimated using hourly and daily data over a one-year period. The data, including 12 different meteorological parameters, were taken from the Turkish State Meteorological Service. The two-parameter Weibull and Rayleigh distributions, which are the most widely preferred models in wind energy studies, are employed to estimate the wind power potential using hourly wind speed data. The graphical method is implemented to calculate the shape (k) and scale (c) parameters of the Weibull distribution function. Daily average wind speed estimation is performed with artificial neural network-genetic algorithm (ANN-GA) and ANN-particle swarm optimization (ANN-PSO) hybrid approaches. The proposed hybrid ANN-GA and ANN-PSO algorithms provide correlation coefficient values of 0.94839 and 0.94042, respectively, indicating that the predicted and measured wind speed values are notably close. Statistical error indices reveal that the ANN-GA model outperforms the ANN-PSO model
Benevolent childhood experiences in the framework of resiliency theory: Sample of emerging adults
No full text[Abstract Not Available
Long-term durability of thermoplastic elastomer containing antiviral additives for mobility applications
No full textIn the mobility market, there is a demand from customers for antimicrobial protection. As a result, the market has grown considerably to provide antiviral and antimicrobial polymers and coatings. This study examines how the efficacy of a non-commercial antimicrobial thermoplastic elastomer will change over the life of the application. Using an example application of an electric scooter handlebar grip, durability requirements were identified, and antiviral efficacy (exceeding a log value of 3 or >99.9 microbial growth reduction) was compared before and after testing. A scooter handlebar grip was selected as the ideal example application as it was a high-touch surface, with several different riders. During the start of this study, scooter companies were encouraging their riders to disinfect scooter handlebars before riding, use hand sanitizer, and wear gloves. If the handlebar grip could be antimicrobial, then they could eliminate these steps and provide a safe ride for the users. In order to simulate long-term durability, UV exposure, temperature, humidity, artificial sweat, sunscreen, insect repellent, and abrasion tests were performed and evaluated in terms of antiviral activity. Accelerated weathering reduced the virucidal activity of the sample versus unexposed antiviral thermoplastic elastomer (TPE). However, the efficacy increased with contact time from 90% to 96.83% at 30 and 120 min, respectively. Abrasion resistance of antiviral TPE showed a volume loss of 66 mm3 compared to control samples of 83 mm3. The antiviral TPE sample exhibited slightly lower efficacy compared to the control after exposure to the artificial sweat (99.43% vs. 99.95%). Additionally, a skin tolerance test conducted on rabbits showed that antiviral TPE was not an irritant and showed no dermal toxicity. The outcome of this study will lead to the development of long-term durable antimicrobial material for the transportation industry
Hibrit kompozit malzemelerin balistic modellemesi
No full textLisansüstü Eğitim Enstitüsü, Havacılık ve Uzay Mühendisliği Ana Bilim DalıHibrit kompozitler, günümüz endüstrisinde gelişmiş ve karmaşık uygulamalar için temel ve son derece önemli mühendislik malzemelerinden biri haline gelmiştir. Bu çalışmada, katman sayısı aynı kalmak şartıyla, katman tipi ve katman diziliminin, aynı balistik etki altında kompozit malzemelerin davranışları deneysel olarak incelenmiştir. Laboratuvarda vakum infüzyon üretim yöntemi ile 10 adet reçine destekli cam elyaf ve karbon katkılı hibrit kompozit numune elde edilmiştir. Vakum infüzyon üretim yöntemi kullanılarak kompozit malzemelerin üretimi için 200 g/m2 twill cam elyaf kumaş kullanılmıştır. Üretilen kompozitlerin balistik etkilerini incelemek amacıyla STANAG 2920 standartlarına uygun olarak poligonda atış gerçekleştirilmiştir. Belirlenen bu atış testleri sonucunda, merminin kompozit malzemeler üzerinde oluşturduğu hasarlar analiz edilmiştir. Ayrıca, malzemedeki katman düzeni ve katman tipinin mermi hızını nasıl etkilediği analiz edilmiştir.Hybrid composites have become one of the essential and highly important engineering materials for advanced and complex applications in today's industry. In this study, the behaviours of composite materials under the same ballistic effect of layer type and layer arrangement were investigated experimentally, provided that the number of layers remained the same. . In the laboratory, 10 resin-supported glass fibre and carbon doped hybrid composite samples were obtained by vacuum infusion production method. In order to examine the ballistic effects of the produced composites, shooting was carried out in the polygon in accordance with STANAG 2920 standards. As a result of these specified firing tests, the damages caused by the projectile on composite materials were analysed. In addition, it was analysed how the layer order and layer type in the material affect the projectile velocity
A Stochastic Bilevel Programming Model for an Industrial Symbiosis Network
No full text12th International Symposium on Intelligent Manufacturing and Service Systems, IMSS 2023 -- 26 May 2023 through 28 May 2023 -- Istanbul -- 302369A stochastic bilevel model for an industrial symbiosis (IS) network in an eco-industrial park (EIP) is presented in this paper. Companies in IS networks produce final products using mostly by-products rather than raw materials. Companies in these networks are known to share a variety of synergies, including wastes and by-products. They mostly negotiate on the price and amount of the by-products. This negotiation is critical as by-products should be available on time at the right amount for smooth production. Moreover, the use of these by-products should provide savings compared to the use of raw materials so that companies could benefit from IS. However, the fluctuations in the final product demand affect both the EIP management (the leader) and companies (followers) in the network. Therefore, we proposed a stochastic bilevel model where the lower-level problem is a two-stage stochastic programming model. Our findings show that the demand uncertainty has an impact on both parties. © 2024, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd
Kontrollü etoposid salım malzemelerinin geliştirilmesi: Glioblastoma hücrelerinde test edilmesi
No full textLisansüstü Eğitim Enstitüsü, Biyomühendislik Ana Bilim Dalı, Biyomühendislik Bilim DalıEtoposid, kanser tedavisinde kullanılan bir kemoterapi ilacıdır. Bu ilaç, kanser hücrelerinin büyümesini ve çoğalmasını engelleyerek etki gösterir. Etoposid, genellikle solid tümörler, lenfoma ve lösemi gibi çeşitli kanser türlerinin tedavisinde kullanılır. Etoposid, DNA replikasyonu ve hücre bölünmesi süreçlerini etkileyerek çalışır. İlacın ana mekanizması, topoizomeraz II enzimini inhibe ederek DNA çiftinin çözülmesi ve tekrar birleşmesi süreçlerini etkiler. Etoposid, bu enzimin normal işlevini engelleyerek DNA'nın doğru bir şekilde çoğaltılmasını ve hücre bölünmesinin tamamlanmasını önler. Etoposid, onkologlar tarafından belirli kanser türlerinin tedavisinde kullanılır. Etoposidin etkisi, kullanıldığı kanser türüne, hastanın genel sağlık durumuna ve diğer tedavi yöntemlerine bağlı olarak değişebilir. Bu çalışmada, farklı konsantrasyonlarda etoposid yüklü HSA-nanopartiküller ile boş HSA nanopartiküller sentezlenmiş ve bu nanopartiküller kullanılarak moleküler baskılanmış HEMA/jelatin kriyojeller sentezlenmiştir. Hidroksietil metakrilat (HEMA) bazlı kriyojeller, taramalı elektron mikroskobu, zeta-sizer partikül boyutu analizi ve şişme testleri ile karakterize edilmiştir. Kriyojellerin içerisine yüklenen Etoposid'in miktarına bağlı olarak salınım kinetiği incelenmiş; Etoposid'in Glioblastoma hücreleri üzerindeki etkisini inceleyebilmek için ise sitotoksisite testi yapılmıştır. Sonucunda jele yüklenen Etoposid'in hücrelere doğrudan uygulanan Etoposid'den daha etkili olduğu ortaya çıkmıştır.Etoposide is a chemotherapy drug used to treat cancer. This medicine works by preventing the growth and proliferation of cancer cells. Etoposide is often used to treat various types of cancer, such as solid tumors, lymphoma, and leukemia. Etoposide works by affecting the processes of DNA replication and cell division. The main mechanism of the drug is to inhibit the enzyme topoisomerase II, affecting the processes of unwinding and recombination of the DNA pair. Etoposide inhibits the normal function of this enzyme, preventing DNA from being properly replicated and cell division from completing. Etoposide is used by oncologists to treat certain types of cancer. The effect of etoposide may vary depending on the type of cancer for which it is used, the patient's general health condition, and other treatment methods. In this study, empty HSA particles were synthesized with HSA-nanoparticles loaded with etoposide at different concentrations, and molecularly imprinted HEMA/gelatin cryogels were synthesized using these particles. Hydroxyethyl methacrylate (HEMA)-based cryogels were characterized by scanning electron microscopy, zeta-sizer particle size analysis, and swelling tests. Release kinetics were examined depending on the amount of Etoposide-loaded into the cryogels; A cytotoxicity test was performed to examine the effect of Etoposide on Glioblastoma cells. As a result, it turned out that Etoposide-loaded into the gel was more effective than Etoposide applied directly to the cells
Free and forced vibration analysis of FG-CNTRC viscoelastic plate using high shear deformation theory
No full textThis paper investigates the dynamic behavior of a simply supported viscoelastic plate made of functionally graded carbon nanotube reinforced composite under dynamic loading. Carbon nanotubes are distributed in 5 different shapes: U, V, A, O and X, depending on the shape they form through the thickness of the plate. The displacement fields are derived in the Laplace domain using a higher -order shear deformation theory. Equations of motion are obtained through the application of the energy method and Hamilton's principle. The resulting equations of motion are solved using Navier's method. Transforming the Laplace domain displacements into the time domain involves Durbin's modified inverse Laplace transform. To validate the accuracy of the developed algorithm, a free vibration analysis is conducted for simply supported plate made of functionally graded carbon nanotube reinforced composite and compared against existing literature. Subsequently, a parametric forced vibration analysis considers the influence of various parameters: volume fractions of carbon nanotubes, their distributions, and ratios of instantaneous value to retardation time in the relaxation function, using a linear standard viscoelastic model. In the forced vibration analysis, the dynamic distributed load applied to functionally graded carbon nanotube reinforced composite viscoelastic plate is obtained in terms of double trigonometric series. The study culminates in an examination of maximum displacement, exploring the effects of different carbon nanotube distributions, volume fractions, and ratios of instantaneous value to retardation times in the relaxation function on the amplitudes of maximum displacements
Integrating Usability into Software Engineering Course Projects
No full textThis study presents a case study of the integration of usability evaluation into the development of task based information system prototypes in undergraduate software engineering course projects within a problem-based learning (PBL) approach. As part of the course, usability evaluation was integrated into the software development process, and the usability evaluation performance (UEP) of the projects was assessed in terms of the following criteria: effectiveness, efficiency and problem validity. It also analyzed the problem solution rate of the projects and their correlation between UEP criteria. Additionally, the study in-depth analyzed the students' final conclusions regarding the design process. The relationship between UEP criteria and the problem solving rate was examined using Spearman correlation analysis. In addition, final conclusions and problem solving behaviors were analyzed through document and thematic analysis techniques. The results supported that there is a significant correlation between usability evaluation criteria and problem solving rate. The main themes that emerged regarding usability problem solving behaviors were navigation design, error handling, database connection, algorithm design, search matching, system-user communication design and others. Final conclusions showed that project teams gained valuable insights into user-centered design, solved critical usability problems and improved their prototype design. It can be concluded that the integration of usability into software engineering education using the above approach contributes to students' understanding of user-centered interaction design