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An intelligent navigation and obstacles avoidance system for autonomous drones
No full textGünümüzde otonom İnsansız Hava Araçları (İHA’lar) özellikle yapılandırılmamış ve engelli ortamlarda görev icrası için giderek daha fazla önem kazanmaktadır. Bu tür karmaşık alanlarda güvenli navigasyon ve etkili alan kapsaması, gelişmiş algılayıcı sistemleri ve yapay zeka tabanlı karar verme mekanizmalarını gerekli kılmaktadır. Bu tez çalışmasında, karmaşık ve engellerle dolu orman benzeri ortamlarda otonom İHA güvenli ve verimli kapsama hareketini gerçekleştirebilmesi amacıyla Derin Pekiştirmeli Öğrenme (DPÖ) tabanlı hibrit bir seyrüsefer sistemi geliştirilmiştir. Geliştirilen sistem, küresel düzeyde deterministik bir çim biçme (lawnmower) kapsama planlayıcısı ile yerel düzeyde engel kaçınma yeteneği sağlayan Yumuşak Aktör-Kritik (YAK) algoritmasının entegrasyonuna dayanmaktadır. Sistem, Robot İşletim Sistemi (RİS) Noetic altyapısı ve Gazebo simülasyon ortamı kullanılarak test edilmiştir. Simülasyon senaryoları, farklı boyut ve yoğunlukta engeller içeren 25×25 m ve 50×50 m ölçülerindeki alanlar olarak belirlenmiştir. Her iki senaryoda da sistemin engel algılama hassasiyeti, kaçınma davranışının tutarlılığı ve alan kapsama verimliliği kapsamlı bir şekilde değerlendirilmiştir. Elde edilen sonuçlar, YAK tabanlı engel kaçınma modülünün yüksek yoğunluklu engel bölgelerinde bile kararlı ve etkili bir kaçınma tepkisi ürettiğini ortaya koymuştur. Ayrıca sistem, engellerden kaçınırken görev bütünlüğünü koruyarak kapsama görevini tamamlayabilmiştir. Bu çalışma, DPÖ tabanlı otonom seyrüsefer sistemlerinin, yapılandırılmamış ortamlarda güvenli ve esnek operasyonlar gerçekleştirmesi adına umut verici sonuçlar ortaya koymakta ve benzer uygulamalar için güçlü bir temel sunmaktadır.In recent years, autonomous Unmanned Aerial Vehicles (UAVs) have gained increasing importance, particularly for mission execution in unstructured and obstacle-rich environments. Safe navigation and efficient area coverage in such complex domains necessitate the integration of advanced sensing technologies and artificial intelligence-based decision-making mechanisms. This thesis presents the development of a hybrid navigation system based on Deep Reinforcement Learning (DRL) to enable safe and efficient coverage operations by autonomous UAVs in cluttered, forest-like environments. The proposed system combines a deterministic global lawnmower coverage planner with a local obstacle avoidance module powered by the Soft Actor-Critic (SAC) algorithm. The framework was implemented and evaluated using the Robot Operating System (ROS) Noetic integrated with the Gazebo simulation environment. Experimental scenarios were designed within 25×25 m and 50×50 m areas containing randomly distributed static obstacles of varying densities. In both scenarios, the system’s obstacle detection sensitivity, avoidance behavior consistency, and area coverage efficiency were comprehensively evaluated. The results demonstrate that the SAC-based avoidance module consistently produced stable and effective responses, even in high-density obstacle regions. Moreover, the UAV successfully completed the coverage mission while maintaining task integrity through adaptive path reconfiguration during obstacle encounters. This study highlights the potential of DRL-based autonomous navigation systems to perform safe and resilient operations in unstructured environments, offering a robust foundation for future research and real-world applications
On the converse conditional proposition: Reductions, notation and testing
No full textBu çalışmada, evrik koşul önermesi üzerinde durulmaktadır. Bu önermeyle ilgili indirgeme, notasyon ve denetleme konularına yer verilmektedir. Bu konular, doğruluk tablosu yönteminden yararlanılarak ele alınmaktadır. Bu yöntemle evrik koşul önermesinin doğruluk fonksiyonları tespit edilip hangi önermelerin doğrudan ve hangi önermelerin dolaylı olarak evrik koşul önermesine indirgenebilecekleri, evrik koşul önermesinin hangi önermelere indirgenebileceği, evrik koşul önermesinin farklı varyasyonlarının iki boyutlu notasyonunun nasıl yapılabileceği ve evrik koşul önermesinin çözümleyici çizelge kurallarıyla indirgeyici çizelge kurallarının neler olabilecekleri ortaya koyulmaktadır. Ayrıca evrik koşul önermesi içeren anlatımlara yönelik doğruluk tablosu, çözümleyici çizelge ve indirgeyici çizelge yöntemleriyle tutarlılık, eşdeğerlilik ve geçerlilik denetlemeleri yapılarak belirlenen kuralların nasıl uygulanabilecekleri gösterilmektedir.This study focuses on the converse conditional proposition. Reduction, notation and testing issues related to this proposition are included. These issues are addressed using the truth table method. With this method, the truth functions of the converse conditionals are determined, and it is revealed which propositions can be reduced directly and which propositions indirectly to the converse conditional proposition, to which propositions the converse conditional proposition can be reduced, how two-dimensional notation of different variations of the converse conditional proposition can be made, and what will be the truth tree and reduced truth tree rules of the converse conditional proposition. In addition, it is shown how the determined rules can be applied by checking consistency, equivalence and validity with truth table, truth tree and reduced truth tree methods
Effect of atmospheric pressure plasma treatment on the wettability and aging behavior of metal surfaces
No full textAtmospheric pressure plasma (APP) applications have started to come to the fore today because of their fast and stable applicability to material surfaces and many advantages compared to plasma applications made under vacuum. With APP, it is possible to improve the surface energies, adhesion behavior and surface mechanical properties of materials. However, the changes obtained are not permanent since the surface tends to return to its untreated original state after plasma treatment. In this study, the wettability of APP treated metal surfaces, aging behavior and storage conditions that can delay the return of the surface to its untreated initial state were investigated. While one type of material (H300LAD), two different plasma treatments (cold and hot) and three different plasma treatment numbers (1, 2 and 3 times) were determined as test parameters; two different ambient conditions such as air and water (for 1, 10 and 60 min) were chosen as the storage conditions that can delay the return of the plasma treated surfaces to their original state. In addition, the effects of temperature on the aging time were investigated for two different temperature values (-20 degrees C and 30 degrees C). The effects of the applied plasma type, plasma treatment number, the storage conditions in which the samples were kept and the temperature on the aging behavior were evaluated and the conditions that could delay the aging time were investigated. The results showed that aging is greatly affected by the type of plasma applied to the surfaces, the storage conditions in which the samples were kept and the temperature
Bulgaria Parthicopolis (Güneybatı Bulgaristan) Katedral Bazilikası’nın (No. 4) nartheksindeki mozaik spolia kullanımı
No full textThe Cathedral Basilica of Parthicopolis, also known as Basilica No. 4, the Episcopal one, is part of a complex in which in the period second quarter-middle of the 4th century and the end of the 5th century, a separate basilica has been built, supplied additionally by a narthex, a baptistery, an atrium, an Episcopaeion with chapel and scriptorium, a skeuophylakion (σκευοφυλάκιο), a kitchen and other premises. During the second building phase of the first building period, a two-armed ambo oriented along its long axis east-west has been installed in the southern part of the central nave. When it was dug into the mosaic carpet of the nave, the removed pieces and some of the red mortar with the tesserae were not thrown away. They were reused as spolia not for their original purpose, but to level out the rows of stones in the construction of the bench and the base of the staircase attached to it for the gallery on the second floor, which was built in the northern part of the narthex. Some of the fragments were also used for decoration – the base of the bench, which was plastered in height with mortar. This unusual use of the early Christian mosaic is observed for the first time among the monuments from the early Byzantine Period in Macedonia and Thrace (today on the territory of the Republic of Bulgaria).Parthicopolis Katedrali Bazilikası - diğer adıyla 4 Numaralı Bazilika ya da Episkopal Bazilika - İS 4. yüzyılın ikinci çeyreğinden 5. yüzyılın sonlarına kadar işlev gören bir kompleksin parçasıdır. Bu kompleks; nartheks, baptisterion, atrium, episkopeion (şapel ve skriptoriumla birlikte), skeuophylakion (σκευοφυλάκιο), mutfak ve çeşitli yan mekânları içeren ayrı bir bazilikayla genişletilmiştir. İlk inşa evresinin ikinci aşamasında, ana nefin güney bölümüne uzun ekseni doğu–batı yönünde konumlanmış iki kollu bir ambon (ambo) yerleştirilmiştir. Bu uygulama sırasında, nefin mozaik döşemesinden çıkarılan parçalar ve üzerlerindeki kırmızı harç ile tesserae atılmamış; spolia (ikincil kullanım malzemesi) olarak, özgün işlevlerinden farklı biçimde yeniden değerlendirilmiştir. Bu parçalar, ikinci kat galerisine bağlanan merdiven kaidesi ile ona bitişik oturma sekisinin (bench) taş sıralarını tesviye etmek amacıyla kullanılmıştır. Bazı parçalar ise dekoratif unsurlar olarak, harçla sıvanmış sekilerin tabanında değerlendirilmiştir. Bu sıra dışı mozaik yeniden kullanımı, erken Bizans Dönemi’ne ait Makedonya ve Trakya (günümüzde Bulgaristan Cumhuriyeti sınırları içinde) anıtları arasında ilk kez tespit edilmiştir
Silent persistence: Molecular evidence of clonal transmission in fluconazole-resistant candida parapsilosis hospital outbreaks over decades
No full textFluconazole-resistant Candida parapsilosis has emerged as a significant nosocomial pathogen, contributing to extensive outbreaks with severe clinical implications. Despite increasing evidence of clonal transmission, the genetic mechanisms that facilitate the persistence of hospital reservoirs remain inadequately characterized. We aimed to characterise the long-term molecular epidemiology of fluconazole-resistant Candida parapsilosis bloodstream isolates (n = 47) collected between 1997 and 2019 at a tertiary centre. All isolates underwent microsatellite analysis using three polymorphic markers (CP1, CP4, B5). Genetic diversity, temporal distribution, and clonal relationships were assessed through phylogenetic analysis and discriminatory power calculations. Microsatellite analysis revealed minimal genetic diversity (combined discriminatory power: 0.7114), with only six distinct genotypes identified. Two dominant clones (Genotype-1: 23.4%, Genotype-2: 46.8%) persisted throughout the study, showing apparent spatiotemporal clustering in surgical and intensive care units. Phylogenetic analysis demonstrated tight genetic clustering, consistent with prolonged clonal persistence across multiple years and clinical departments. Our findings provide strong molecular evidence consistent with persistent, multi-year clonal transmission; however, definitive confirmation will require higher-resolution genomics and epidemiologic linkage. These results underscore the need to strengthen infection-control practices to curtail sustained clonal persistence within the hospital
Long-term cladribine experience in relapsing-remitting multiple sclerosis
No full textWe present the case of a 40-year-old male patient who was diagnosed with multiple sclerosis (MS) at age 16. Initially, he was treated with glatiramer acetate, but he later received cladribine due to high disease activity. After participating in the CLARITY study in 2007, he achieved 10 years of clinical and radiological stability (NEDA-3) with a single cladribine treatment. In 2019, relapse symptoms of optic neuritis and a new enhancing lesion on an MRI scan prompted the initiation of a second cladribine treatment cycle. Despite the appearance of a new asymptomatic lesion prior to the second-year dose, therapy was continued without modification. The patient remained free of relapses, disability progression, and radiological activity for the following three years. This case illustrates cladribine's potential for long-term efficacy, even with intermittent disease activity, and supports its use as a viable option for sustained disease control in relapsing MS
Pseudohyperkalemia diagnosis: A key to reducing side effects of potassium-lowering medications
No full textArtificial neural network-assisted supercell thunderstorm algorithm for optimization of real-world engineering problems
No full textThis study presents an artificial neural network (ANN)-assisted modified supercell thunderstorm optimizer (MSTO) for solving complex industrial component optimization problems. Inspired by the natural phenomena of spiral motion, tornado formation, and jet streams within supercell thunderstorms, the STO algorithm is enhanced with ANN integration to improve exploration, exploitation, and convergence rates. The algorithm is validated across five constrained engineering problems: cantilever beam optimization, industrial grinding cost optimization, tubular column design, diaphragm spring weight minimization, and fin and tube heat exchanger (FTHE) cost optimization. These results confirm MSTO's superior performance over recent metaheuristics, highlighting its potential for high-precision, stable, and efficient solutions across structural, thermal, and mechanical design domains
Uridine treatment protects against blood-brain barrier disruption in a rat model of li-pilocarpine-induced status epilepticus
No full textIntroduction Blood-brain barrier (BBB) disruption is one of the most striking changes triggered by status epilepticus, which deserves specific attention in terms of novel treatment approaches targeting epileptogenesis. Uridine is a pyrimidine nucleoside with neuroprotective, antiepileptic and antiepileptogenic effects; however, its mechanism of action is not fully characterized. In this study, we aimed to investigate the short-term outcomes of uridine treatment on status epilepticus-induced-BBB dysfunction in an animal model.Methods Status epilepticus was induced by lithium and pilocarpine administration in male Sprague-Dawley rats which were post-treated with intraperitoneal injection of saline or uridine (500 mg/kg b.w.; twice a day) for 2 days. Blood-brain barrier structural integrity was assessed by measuring expressions of endothelial tight junction proteins zonula occludens-1 (ZO-1) and occludin, matrix metalloproteinases (MMP-2 and MMP-9), aquaporin-4 (AQP4) water channel and its anchoring protein alpha 1-syntrophin in hippocampal tissue 48 h after SE. Additionally, BBB permeability was determined by measuring brain edema and serum S100B levels.Results The data showed that uridine significantly prevented the reduction in ZO-1 and alpha 1-syntrophin protein levels and attenuated serum S100B levels, indicating protective effects on BBB integrity and AQP4 polarization. In contrast, uridine enhanced brain water content in SE-induced rats, a finding that might be a result of maintained AQP4 polarization and enhanced cytotoxic edema.Discussion Together, our results showed for the first time that post-seizure treatment with uridine provides protection against BBB disruption in an experimental SE model; nevertheless, the long-term effects of this treatment warrant further investigation
Ardl bound testing approach for a green low-carbon circular economy in Turkey
No full textThis study analyzes Turkey's development toward a green economy between 1990 and 2022 within the framework of certain green economic indicators. The data consist of secondary data from the official databases of the World Bank and the Turkish Statistical Institute (TURKSTAT). In the study, the total amount of carbon emissions was chosen as an indicator of green growth, while gross domestic product per capita (GDP) represents economic growth, domestic loans granted by banks to the private sector (as a percentage of GDP) and foreign direct investment represent financial development, and electricity generation represents pollution. To determine whether the variables are cointegrated and to determine the direction and strength of the relationship between the variables, the ARDL bounds test and the FMOLS and DOLS long-run estimators were used. Finally, Toda Yamamoto (TY)-Granger tests were performed to determine causality. The long-term relationship between the variables was confirmed by the results of the ARDL bounds test. The error correction coefficient (CointEq(-1)) was estimated to be statistically significant and negative (-0.757) when the short-term analysis was performed. This result shows that the short-term imbalances will be corrected in less than a year, and the system will approach the long-term equilibrium. In the long-term analysis of the model, all variables selected to explain the dependent variable were found to have a statistically significant impact on the dependent variable. The GDP per capita variable, the indicator of economic growth, has a negative effect on the dependent variable, while the other independent variables have a positive effect. The results of the causality analysis indicate that the dependent variable carbon emissions (CO2) has a unidirectional causality relationship with domestic credit provided to the private sector by banks (DC), which represents financial development, and with total electricity production (EP), which serves as an indicator of pollutants