repository.title.prefixSustainable Development Goal "Goal 12: Responsible Consumption and Production" ile 'a göz atma

Sustainable Development Goal "Goal 12: Responsible Consumption and Production" ile 'a göz atma

3D face animation generation from audio using convolutional neural networks

(Graduate School, 2022) Ünlü, Türker ; Sarıel, Sanem ; 504171557 ; Computer Engineering Programme

Problem of generating facial animations is an important phase of creating an artificial character in video games, animated movies, or virtual reality applications. This is mostly done manually by 3D artists, matching face model movements for each speech of the character. Recent advancements in deep learning methods have made automated facial animation possible, and this research field has gained some attention. There are two main variants of the automated facial animation problem: generating animation in 2D or in 3D space. The systems that work on the former problem work on images, either generating them from scratch or modifying the existing image to make it compatible with the given audio input. The second type of systems works on 3D face models. These 3D models can be directly represented by a set of points or parameterized versions of these points in the 3D space. In this study, 3D facial animation is targeted. One of the main goals of this study is to develop a method that can generate 3D facial animation from speech only, without requiring manual intervention from a 3D artist. In the developed method, a 3D face model is represented by Facial Action Coding System (FACS) parameters, called action units. Action units are movements of one or more muscles on the face. By using a single action unit or a combination of different action units, most of the facial expressions can be presented. For this study, a dataset of 37 minutes of recording is created. This dataset consists of speech recordings, and corresponding FACS parameters for each timestep. An artificial neural network (ANN) architecture is used to predict FACS parameters from the input speech signal. This architecture includes convolutional layers and transformer layers. The outputs of the proposed solution are evaluated on a user study by showing the results of different recordings. It has been seen that the system is able to generate animations that can be used in video games and virtual reality applications even for novel speakers it is not trained for. Furthermore, it is very easy to generate facial animations after the system is trained. But an important drawback of the system is that the generated facial animations may lack accuracy in the mouth/lip movement that is required for the input speech.
50 MV kurulu güçteki güneş kulesi santralinin tasarımı ve modellenmesi

(Lisansüstü Eğitim Enstitüsü, 2022) Karakaş, Yusuf ; Karabetoğlu, Sevan ; 708692 ; Enerji Bilim ve Teknoloji Ana Bilim Dalı

Geçmişten günümüze insan faaliyetlerinin sürdürülebilmesini sağlamak amacıyla kullanılan enerji, uygarlığın sürdürülebilirliğinin bileşeni olup, bilimin ve teknolojinin gelişiminde vazgeçilmez bir araçtır. Bugün sahip olunan teknolojik ve bilimsel birikimlerin geliştirilmesi ve yeni bilimsel, teknolojik buluşların ortaya çıkması için direkt veya dolaylı enerji ihtiyacı bulunmaktadır. Enerji miktarı aynı zamanda ülkelerin gelişmişlik düzeyinin bir göstergesi olup, enerji gelişmiş ve gelişmekte olan ülkelerin ana ihtiyaçlarından biridir ve dünya genelinde enerji tüketimi sürekli olarak artmaktadır. Fosil yakıtlar günümüzde ihtiyaç duyduğumuz enerjinin büyük bir kısmının üretildiği kaynaklar olup, geri kalan kısmı nükleer ve yenilenebilir enerji kaynaklarından yararlanılarak üretilmektedir. Fosil yakıtların yakılmasıyla ortaya çıkan sera gazlarının atmosferdeki yoğunluğunun artmasıyla küresel ortalama yıllık sıcaklık artışı gibi küresel iklim değişikliği sonuçları gözle görülür nitelikte ivme kazanmıştır. Bu da neredeyse tüm canlı ekosistemlerini barındıran habitatları olumsuz etkilemekte ve devasa miktarda CO2' in çok kısa sürede atmosfere salınımı sebebiyle canlı türlerinde ölümler hatta soy tükenmesi gibi sonuçları beraberinde getirmektedir. Çevre ve canlılara zarar veren fosil yakıtların kullanımı sürdürülebilinir değildir. Önlem alınmadığı takdirde bu zararların bedelinin çok büyük boyutlara ulaşacağı göz ardı edilmemelidir. Bundan dolayı fosil enerji kaynaklarının alternatifi olan yenilenebilir enerji kaynakları kullanılarak üretilen enerjinin artırılması ve sıfır emisyona ulaşılması zorunluluğu gün geçtikçe daha iyi fark edilmesi sağlanmalıdır. Yenilenebilir enerji kaynakları arasında en çok bulunan ve jeotermal enerji hariç diğer yenilenebilir enerji kaynaklarının kaynağı güneş enerjisidir. Güneş enerjisinden faydalanılarak direkt veya dolaylı olmak üzere iki metotla enerji üretimi gerçekleştirilir. Direkt yöntemle elektrik üretimi gerçekleştiren fotovoltaik hücreler yarı iletken malzemelerden yapılır ve bir diyot gibi çalışarak güneş ışığında bulunan enerjiyi fotoelektrik etkiden yararlanarak elektrik enerjisine dönüştürür.
A comprehensive analysis of maritime incidents from a personal injury perspective

(Graduate School, 2024-06-10) Yalçın, Duygu ; Akyüz, Emre ; 512211003 ; Maritime Transportation Engineering

Maritime accidents continue to be a significant concern all around the world. Although the public may mostly associate these incidents with vessels and assets, these incidents not only pose threats to significant financial losses but also have bigger consequences, like harm to the environment and potential risks to human life. Accidents involving property loss, fatalities, injuries, or environmental damage are investigated to determine responsibility and root causes, enabling strategies to prevent future occurrences and enhance maritime safety. Reporting and investigating such incidents are vital and required by international laws and conventions. Organizations have integrated thorough accident reporting and analysis into their operations, resulting in comprehensive reports that help prevent future incidents. For instance, The European Maritime Safety Agency (EMSA) Annual Overview of Marine Casualties and Incidents 2023 report, covering 2014-2022. Average annual fatalities decreased from 114 in 2014 to 38 in 2022, and injuries from 999 in 2014 to 525 in 2022. Additionally, The Transportation Safety Board of Canada reported a similar decline in 2022, with marine fatalities dropping to seven from an average of fifteen. Similarly, The Maritime Accident Investigation Branch (MAIB) investigates UK maritime accidents and publishes annual reports. From 2013 to 2022, an average of 116 commercial ship crew members were injured annually. Despite these decreasing trends in the total number of casualties, a significant increase is observed in upper limb injuries, particularly hands, and fingers in the reports between 2020 to 2022. This study aims to identify trends causing personal injuries and compare them with findings from MAIB. Such a comparison will help determine whether injury trends are consistent across different organizational environments or if they differ significantly. The ultimate goal is to obtain insights that will guide the development of more effective prevention strategies and safety measures tailored to the unique conditions of the ship's organizational structure. The study examined five years of marine incident data involving approximately 35 MR-sized ships operated by a Turkish ship management company. A comprehensive analysis of variables and root causes of injuries was conducted using descriptive statistics. The company's incident management procedure was integrated with the Marine Systematic Cause Analysis Technique (MSCAT) for root cause analysis. Additionally, the European Statistics on Accidents at Work (ESAW) classification system was used to further explore numerous factors contributing to injuries. The research analyzed 6,863 qualitative maritime incident reports collected from thirty-five different ships managed by the same company between 2018 and 2023. These reports, a primary qualitative data source, included detailed descriptions of the incident's outcome, severity, type of loss or potential loss, event sequences, and environmental conditions. The methodology employed a data-driven approach, incorporating statistical analysis to interpret the semi-structured and unstructured narrative descriptions. This process began with the preparation of data according to the company's incident management procedures, involving the compilation, classification, and formatting of the data. Each report underwent manual screening to verify completeness. Subsequently, the data were organized and converted into quantitative variables for statistical analysis, while preserving the original text for content analysis. The research focused on four main variables frequently used in maritime accident studies: accidents, near misses, unsafe acts, and conditions. Within this framework, near misses, unsafe acts, and conditions were treated as leading indicators, while accidents were considered lagging indicators. Incidents resulting in personal injuries were analyzed in terms of the severity and location of the injuries, the work processes involved, contributing materials and agents, modes of injury, affected body parts, and root causes. The analysis adhered to the company's incident management procedures, employing MSCAT mapping for detailed root cause analysis and the ESAW classification to further delineate the specifics of the injuries. This comprehensive methodological approach systematically identified and addressed factors contributing to injuries, enhancing the understanding of maritime safety dynamics. The data and statistics used in this analysis do not include personal identifiers such as age, gender, or nationality. Furthermore, information regarding the ranks of individuals involved was not categorized. This decision was based on the understanding that errors are normal and can occur regardless of an individual's rank, gender, or nationality. This approach reflects a focus on systemic factors rather than personal attributes or hierarchical status in understanding incidents. The analysis of data from this maritime company revealed that 37% of all incidents resulted in injuries ranging from minor to severe. Approximately 60% of these injuries were minor and treated with first aid, 27% required medical treatment, and 9.6% led to workday loss and sometimes urgent evacuation from the ship. The areas with the highest occurrence of personal injuries were the engine room (29%), the main deck (19%), and the provision storage areas and galley. The most common types of accidents were being struck by moving objects, slipping, tripping, falling, and bumping into objects. Slips and trips were notably prevalent in critical incidents, accounting for 41% of such cases. The study highlighted that hand and finger injuries were the most frequent, comprising 35% of injuries, consistent with MAIB annual reports. These injuries also accounted for 20% of critical injuries, underscoring their potential severity in maritime environments. Immediate factors contributing to injuries included the improper use of personal protective equipment, failure to adhere to safety procedures, and inadequate securing and protection. In 51% of personal injury accidents, the primary cause was identified as a lack of competence, typically characterized by a lack of situational awareness and risk perception. The study suggests that future research might employ statistical methods such as regression analysis and predictive modeling to identify patterns within datasets. Additionally, collecting more company-specific data and expanding the literature will provide a more comprehensive perspective on injury trends.
A dataset quality enhancement method for fine-grained just-in-time software defect prediction models

(Graduate School, 2024-07-01) Fidandan, İrem ; Buzluca, Feza ; 504211520 ; Computer Engineering

Recently developed fine-grained JIT-SDP models offer individual defect-inducingness predictions for each changed file in commits, unlike conventional JIT-SDP models that only predict defect-inducingness for commits. These models also cost-effectively reduce the risk of missing defect-inducing changes in the effort-aware JIT-SDP models by allowing developers to review only defect-inducing files in a commit. Building machine learning models is a data-dependent process, so the quality of the data is crucial. Low data quality negatively affects the predictive performance, interpretability, and scalability of machine learning models. The novelty in the thesis is a two-phased method to improve the quality characteristics of the dataset, including uniqueness, validity, accuracy and relevance, based on the experience and observations in software development for fine-grained JIT-SDP models. In the first phase, miscalculated features are sometimes deleted and sometimes corrected under the right conditions to ensure uniqueness, validity and accuracy. In the second phase, file changes in the commits that have little or no impact on future defects are excluded from the dataset to provide relevance. The proposed data quality improvement method is applied on Trautsch et al.'s dataset. In the data set, there are two different automatically assigned labels by the SZZ algorithm, which includes two basic steps: identifying the bug-fix purpose in full changes or some blocks in changes, and backtracking for each deleted line bug-fix purpose locations to find the changes that previously added them. The reason for the label differences lies in the methods used to identify bug-fix purpose changes. Predictive performance improvements in fine grained JIT-SDP models are then demonstrated when the proposed data quality improvement method is used for within-project and cross-project settings. In within-project setting, time-sensitive validation approach is used. Time-sensitive validation approach first creates three-month training instance groups and one-month test instance groups based on ascending time order, then trains separate models for each instance group and measures their prediction performances, and finally takes arithmetic average of the predictive performance results to get an overall result. For both within-project and cross-project settings, two types of datasets are used: datasets with and without proposed data quality improvements. Model training and evaluation steps are performed for each combination of the features including JIT metrics, static code metrics, PMD static analyzer metrics, and all of them, as well as Adhoc and ITS labels. In addition, CFS is also applied to the dataset with data quality improvements to investigate whether better or same prediction performance can be achieved with cleaner and more explainable models. Random Forest is used for training with SMOTE to balance dataset. Predictive performances are assessed by F1 score. In both within-project and cross-project settings, proposed data quality improvements yielded higher F1 scores than the baseline. Additionally, in cross-project setting, CFS always increased F1 scores. So, the proposed data quality improvement method may help build better fine-grained JIT-SDP models.
A decolonial analysis of urban and regional planning education in the global south

(Graduate School, 2024-11-04) Şen, İpek ; Koramaz, Turgay Kerem ; 502102813 ; Urban and Regional Planning

Through a mixed-methods approach, this thesis compares how the higher education institutions in the Global South conceptualize and act on the decolonization of urban planning education. The main research question is: How do scholars in the Global South perceive and conceptualize the decolonization of urban planning education? The questions to investigate the issues further are as follows: What obstacles and limitations hinder the decolonizing efforts from succeeding in urban planning education? What methodologies do the Global South scholars use to decolonize the urban planning education curriculum in their contexts? What decolonizing methodologies can Turkish planning schools create to encourage local knowledge generation and resist the domination of Eurocentric norms? To answer this question, 17 scholars from 11 countries in the Global South and six former and current members of the Turkish Planning Schools' Association were interviewed. Additionally, all published documents by the association were analyzed. The thesis followed a Constructivist Grounded theory (CGT) methodology as its primary approach and supported it with additional quantitative analyses of the collected documents. Interestingly, the Global South categorization and the inclusion of Türkiye were also received with surprise by many. CGT theoretical coding also revealed differences in conceptualizing and approaching the decolonization phenomenon. The Global South scholars' narration and approach showed a more optimistic and critical arc toward urban planning education and practice, starting with contemplation, continuing with expressing concern about the future of the profession, but then concluding with a new reality of constructing practices and insurgent actions. However, Türkiye followed a more hesitant arc, starting with hesitation, continuing with contemplation with little critical engagement, and ending with a narrative of absence. Significantly few scholars addressed the need to generate local knowledge and radical curriculum change. Instead, they were concerned about the lack of resources across universities and departments regarding place, equipment, and teaching faculty. The results showed several overlaps between countries in terms of challenges and issues regarding education and urban planning practice. The categorical findings of this thesis show that in all interviewed institutions, there are problems concerning how planners are trained and equipped to address issues such as population increase, climate change, land ownership and housing, sustainable and affordable transport, and urban poverty.
A fair division approach to understanding distribution principles in Islamic law of inheritance

(Graduate School, 2023-10-24) Doğan, Burak ; Ertemel, Sinan ; 412182002 ; Economics

This thesis embarked on a meticulous investigation of selected legal disputes from the annals of Islamic law, modelling them as claims problems, surplus-sharing problems, and innovatively introducing a new fair division problem termed as a "modified claims problem." It generalizes solutions proposed by scholars and jurists into distribution rules, framed by axioms, and conducted a comparative axiomatic analysis with classic division rules. A significant revelation of our analysis was the alignment of the Doctrine of 'Awl (AWL), used in Awliyya cases within Islamic law, with the Proportional Rule when it comes to claims problems. Similarly, for surplus-sharing problems, the Doctrine of Radd (RADD), used in Raddiyya cases, mirrors the Proportional Rule. We uncovered that the Munazaa (MUN) Method, proposed by Abu Hanifa, aligns with the Concede-and-Divide (CD) Rule. This method was inferred from Abu Hanifa's contested garment problem and the case of the sword, which parallel the solution to the contested garment problem of Talmud. Furthermore, we introduced a new concept, the Modified Claims Problem, which incorporates the constraint of limited liability. In this context, Abu Yusuf's (AY) Method was generalized into a distribution rule and found alignment with both the Constrained Ibn Ezra's (CIE) Method and the Constrained Shapley Values. This in-depth exploration significantly bolsters the current literature on fair division and Islamic law by presenting a new type of fair division problem and characterizing novel fair division rules. It represents a pioneering effort to explore Islamic legal disputes from a fair division perspective, setting a solid foundation for future research endeavours. Our study augments the traditional literature on Islamic inheritance law, which has primarily offered historical, social, and legal perspectives to comprehend distributions in contentious cases. We enrich this approach by introducing an axiomatic analysis that yields a comprehensive normative understanding of complex Islamic law disputes, emphasizing the inherent normative aspects. In an intriguing revelation, our study exposes parallels between Jewish and Islamic inheritance laws in terms of their principles and applications, an aspect scarcely explored by previous studies. A unique discovery is that an allocation common in Islam aligns with a rule known as the non-Jewish rule. We note that Abu Yusuf's distribution method predates Ibn Ezra's by over three centuries, suggesting potential Islamic origins for the rule attributed to Ibn Ezra. This adds a novel dimension to comparative studies, which have primarily scrutinized whether Islamic law principles borrowed rules from Jewish law. We recommend future research to amass more examples of fair division problems throughout Islamic history and further study methods of Islamic sharing. These initiatives could lead to the characterization of additional Islamic regulations, thereby elucidating unique Islamic principles. An in-depth axiomatic examination of the cases and proposed resolutions is also proposed for future research. Our study has pragmatic implications by bridging the knowledge divide between fair division literature and Islamic law disputes, emphasizing the relevance of cooperative game theory as an instrumental tool for understanding Islamic legal disputes. It encourages a deeper comprehension of the dynamics and outcomes of legal disputes and the socio-cultural factors that influence legal decision-making. Our findings light up debates within Islamic law, fostering a richer understanding of the evolution and interpretation of legal disputes. By acknowledging the variations in methods employed by different authorities, we furnish valuable insights into the Islamic context. Our research has potential to guide policy-making, stimulate discourse, and cultivate a comprehensive approach to dispute resolution in Islamic law. To conclude, our research is groundbreaking in its game-theoretical examination of historical legal disputes within Islamic law. By weaving disputes from Islamic law into the current body of cooperative game theory literature, we provide a unique contribution to the field, which has often neglected disputes stemming from Islamic law. Despite the richness of these disputes for fair division problems, they have been mostly unexplored until now, and this study fills that gap.
A holistic data analytics approach to ship inspection reporting

(Graduate School, 2023-08-08) Biçen, Samet ; Çelik, Metin ; 512192016 ; Maritime Transportation Engineering

Maritime inspection analysis has become an emerging topic in recent years, as practical solutions are sought to improve the pre- and post-inspection analysis in shipping operations. With a focus on finding practical solutions to enhance the pre- and post-inspection process in shipping operations, such as The Oil Companies International Marine Forum (OCIMF) Ship Inspection Report Programme (SIRE), RightShip, The Tanker Management Self-Assessment (TMSA), Chemical Distribution Institute (CDI), there is a growing demand for effective methodologies. The objective of this research is to enhance this field by examining documented observations through the utilization of both natural language processing (NLP) and machine learning (ML) methods. The main goal of this study is to make a valuable contribution to this field by analyzing reported observations. This will be accomplished by employing a combination of natural language processing (NLP) and machine learning (ML) techniques. Additionally, a statistical algorithm model will be utilized to conduct analysis using demographic data. To achieve the objectives of the study, a robust methodology was developed, which leverages the benefits of the American Bureau of Shipping Maritime Root Cause Analysis Tool (ABS-MARCAT). This tool enables the systematic initiation of a potential causes database, incorporating a substantial number of 2383 observations. By employing ABS-MARCAT, the study aims to provide a comprehensive foundation for analyzing and understanding the causes behind reported observations and determining corrective and preventive action tips for elimination of this causes. One of the key contributions of this research is the development of an NLP-based ML algorithm. This algorithm plays an important role in predicting the causes of new entries and determining corrective and preventive action tips in the inspection report's observations. The algorithm's performance demonstrates high accuracy, with results varying between 0.90 and 0.98 across different causation categories. Such accuracy is promising, as it allows for effective identification and classification of causes, providing valuable insights for decision-making in the maritime industry. Another important contribution of this research is the statistical algorithm model that can produce frequencies of causes based on independent variables such as ship name, inspector name, oil major company name and port name. The statistical algorithm model provides predictions about the areas to be considered according to the information required before the inspection. By presenting the frequencies of the cause categories according to the independent variables, it provides a decision support system in the process of predicting the inspection parts to be considered before the inspection. Another important contribution of this research is to suggest corrective and preventive action tips to eliminate the causes of the observations after the causes are identified. The corrective and preventive action tips determined by maritime experts will add a different dimension to the decision-making processes by providing solution suggestions after the analysis of the inspection reports. The pre- and post-inspection analysis model developed in this study holds great potential for enhancing fleet safety and efficiency. By providing maritime executives with an accurate tool to analyze inspection data, it enables them to make informed decisions and take proactive measures to address potential issues. The model serves as a third-party solution for the shipping industry, offering an independent and reliable means of analyzing and assessing inspection data. Looking ahead, future studies are planned to further refine and expand this model. The aim is to conceptualize it as a platform as a service (PaaS) offering, which would enable wider access and utilization by stakeholders in the maritime industry. By transforming the model into a PaaS, it has the potential to become a valuable resource for multiple organizations, facilitating improved fleet safety, operational efficiency, and informed decision-making. In conclusion, this study addresses the emerging field of maritime inspection analysis by developing a robust pre- and post-inspection analysis model. Through the integration of statistical algorithm model, NLP, ML, and the MARCAT tool, the study offers a holistic approach to analyzing reported observations and statistical data. With its high accuracy, the model has the potential to make a significant contribution to the improvement of fleet safety and efficiency. Furthermore, by conceptualizing it as a platform as a service, the study paves the way for wider adoption and application of the model within the shipping industry.
A statistical analysis of ionospheric joule heating driven by interplanetary coronal mass ejections and high speed streams using SWMF/BATS-R-US MHD model

(Graduate School, 2022-07-06) Erdemir, Pelin ; Kaymaz, Zerefşan ; 511191032 ; Atmospheric Sciences

Space weather is the changes in the interplanetary space caused mainly by solar activity. Some of the space weather hazards are disruption of radio communication signals, disruption of electrical systems, increased satellite drag and increased radiation dosage on flights. Thus, the observations and predictions of these space weather events are significantly important with the developing space science and technology. Two major solar phenomena that affect the environment near Earth the most are classified as coronal mass ejections and high speed solar wind streams. Depending on the solar activity, the sunspot cycle, their occurrence rate changes. Due to their origin, occurrence, interplanetary structure and the geomagnetic disturbances they drive, they affect the space weather in different ways and intensities. Solar wind- magnetosphere-ionosphere coupling process is driven differently for each phenomena. The energy budget of the solar phenomena is dissipated into the magnetosphere-ionosphere system resulting in moderate to major geomagnetic disturbances, called geomagnetic storms. Geomagnetic storms are one of the highest contributions to this dissipation is via Joule heating, which is a frictional heating in the ionosphere caused by the electrical currents. Thus, in this study, the main aim is to reveal the differences of this two major phenomena (CMEs and HSSs) in the interplanetary space, then to investigate their driven geomagnetic storms in detail with their phases and finally to compare the Joule dissipation contributions (1) for their structural regions and (2) for the driven geomagnetic storm phases. Hereby, the differences of the coronal mass ejections and high speed solar wind streams would be tracked from their origin in the Sun, to the interplanetary space until they interact with the Earth's magnetosphere-ionosphere system. In the literature it is shown that the two phenomena have different structures and different driven geomagnetic storms. CMEs in the interplanetary space are named as interplanetary coronal mass ejections (ICMEs) that consist of sheath (SH) and magnetic obstacle (MO) regions. The sheath region is followed just after the shock, thut it is a turbulent region with high temperature and speeds. On the other hand, a magnetic obstacle is the highly magnetized part of the ICME, which is generally referred to magnetic cloud with flux-rope pattern. The coronal hole high speed streams in the interplanetary space are named as corotating interaction region high speed streams (CIR/HSS) due to their continuous pattern with the Sun's rotation and longer presence. CIR/HSSs do not have a fast forward shock, thus the parameters do not have an abrupt increase but the density and magnetic field parameters increase before the others due to the compression of the fast and solar wind interaction region. Due to these differences it is thought that both phenomena have different Joule dissipation rate. ICME driven storms are generally moderate to extreme in intensity, whereas the CIR/HSS driven storms are minor to moderate in intensity. Both phenomena have initial, main and recovery phases of their geomagnetic storms. But in the case of ICMEs, the initial phase starts with a storm sudden commencement (SSC) differently from CIR/HSSs due to the fast forward shock. Also the main phase in the ICME driven storms are more intense. The recovery phase in both phenomena can last longer, but in CIR/HSS cases the full recovery is not that clear. Thus, the disturbances can last longer. Overall, it is expected that each phase has a different contribution in Joule heating of the ionosphere. Joule dissipation is known as the heating of the upper atmosphere due to the ionospheric currents and friction of the ion-neutral collisions. It is not a directly observable parameter. And since it is a derived parameter, there are several techniques developed to estimate the heating rate. These methods include using ground based methods together with space-borne measurements and MHD models. Recently, the most preferred approach is to use physics-based models for the estimation of Joule heating. SWMF/BATS-R-US with RCM is one of the latest models developed by CCMC in order to obtain ionospheric electrodynamics parameters by solving MHD equations and then to estimate ionospheric dissipation. Thus, we decided to run the SWMF/BATS-R-US model to estimate Joule heating. Firstly in this study, as solar phenomena, three CME and three HSS cases were selected to investigate. Then, the CME events were selected by using the SOHO/LASCO C2 coronagraph and HSS events were observed from the SDO/AIA telescope images. After the remote sensing observations, WIND spacecraft in L1 point was used to obtain in-situ data measurements. The event intervals are corrected by using ICME and CIR/HSS catalogs. Secondly, the SWMF/BATS-R-US magnetospheric MHD model was run in order to obtain Joule dissipation data covering the event intervals. After obtaining the model outputs, the structural intervals of CMEs and HSSs were determined and the corresponding Joule heating rates per unit time were determined. After, the ICME-driven and CIR/HSS-driven geomagnetic storm phase intervals were determined and the Joule heating rates corresponding to these phases were determined for each. To make a detailed comparison, simple linear regression and multi linear regression analyses were performed for the structural intervals. To compare the structural correlations in order to find out the controlling parameters, energy efficiency analysis was also performed for the geomagnetic storm intervals referring to the magnetospheric processes. By the help of these analyses, it was found that the CMEs lead to the higher rates of Joule dissipation in the upper atmosphere rather than HSSs, mostly due to their magnetic obstacle regions. Also the geomagnetic storm interval resulted in more Joule heating for the CME cases. Main phases of the driven storms from both phenomena were found to relate with the highest Joule heating rate per unit time. With the SLR and MLR analyses, it was found for HSS that their controlling parameters are the geomagnetic activity parameters, whereas the controlling parameters of the CMEs are the solar wind parameters. This result revealed that the Joule heating driven by the HSSs are more effective and produced by the magnetospheric processes, whereas the Joule heating driven by CMEs are less effective and produced by the solar wind energy budget of the phenomena. In Chapter 1, the aim of this study and literature work is introduced. In Chapter 2, solar activity and space weather are defined. Then CME and HSS phenomena are investigated in detail, followed by a description of geomagnetic storms and their phases and energy exchange processes. Chapter 3 explains the Joule heating, existing methods for estimations and the SWMF/BATS-R-US model. Chapter 4 consists of the selection of CME and HSS cases, run details of the MHD model, structural analysis of CMEs and HSS, geomagnetic storm analysis of ICMEs and CIR/HSSs, simple and multi linear regression analyses for all cases and finally the energy efficiency analysis. In Chapter 5, the results are explained and the summary is given with future work recommendations.
A study of mud volcano formation by basin modeling in the lower kura depression, South Caspian basin, Azerbaijan

(Graduate School, 2022) Namazlı, Muhammad ; İnan, Sedat ; 775875 ; Geological Engineering Programme

A mud volcano is a landform that forms as mud, water, and gases are released to the surface of the earth. Mud volcanoes can occur as a result of many geological processes. Since mud volcanoes do not generate lava because they are not fueled by magmatic activity. Mud volcanoes can be as little as one or two meters high and two meters broad or as large as 700 meters high and ten kilometers wide. Sometimes mud-pots are used to describe smaller mud exudations. Lower Kura Depression (LKD) and, South Caspian Basin (SCB) are unique places on Earth where enormous oil and oil-gas-condensate deposits coexist with oil-gas mud volcanoes. The presence of oil-gas and mud activity in nearly every one of this region's explored hydrocarbon sites attests to their intimate relationship. Mud volcanoes (MVs) have deep roots that reach oil and gas production zones, and as a result, they act as fluid passageways of hydrocarbons to higher structural levels. The South Caspian Basin hosts more than 30 % of the World's mud volcanoes. Significantly large mud volcanoes were developed in this area as a result of favorable tectonic processes, depositional settings, and subsurface pressure and temperature conditions. MVs can be many kilometers broad and several hundred meters high in certain areas. As a source of hydrocarbon gases, they feed the hydrosphere and atmosphere with enormous amount of gases that contribute to the the greenhouse effect and climate change. For instance in the LKD, mud volcanoes are associated with oil and gas fields. By means of their explosive eruptions and instability of the nearby gas-saturated sediments, they may also have adverse effects on drilling operations, rig installations, and pipeline routings. The purpose of this study is the investigation of the main causes of mud volcanos in the Lower Kura Depression of the South Caspian Basin in Azerbaijan. In the Lower Kura Depression there are 33 mud volcanoes that are active. The thickness of the sedimentary pile in the Lower Kura Depression reaches 25 km. This indicates that the sediment accumulation in the region is proceeding at a high rate. Avalanche sedimentation is characterized by a high rate of sedimentation exceeding 100 mm/1000 years and 1000 mm/1000 years, respectively. For this reason, high sedimentation rate is known here as one of the factors that cause overpressure and trigger mud volcanoes. For investigating these factors, PETROMOD 2D basin modeling program has been used.
Açık kaynaklı bütünleşik çoklu eklenti yöneticisi tasarımı ve uygulaması

(Lisansüstü Eğitim Enstitüsü, 2023) Uçar, Mustafa ; Doğru, Ahmet Özgür ; 501181660 ; Geomatik Mühendisliği Bilim Dalı

Açık kaynak yazılımı (Open Source Software-OSS), pragmatik olarak yazma kolaylığı ve hibrit çalışmayı desteklemesiyle dünya çapında geliştirici desteği edinerek tescilli yazılımlara uygun bir alternatif olma yolunda hızla ilerlemektedir. OSS'nin bir sonucu olarak birçok yenilikçi iş modeli ve yeni iş fırsatları ortaya çıkmış, pek çok yazılım kendini bi yönde yenilemeye başlamıştır. OSS yüksek teknoloji ve diğer endüstrilerdeki iş modellerinde kritik bir rol oynamaktadır. Bu yapıda geliştirilen yazılımlar ulaşılabilirlik anlamında dünyanın her noktasında bir kullanıcı edinebilmekte ve bu oranda da geri dönüşlerle geliştirilmesine devam edebilmektedir. Bu geri dönüşlerin yanı sıra geliştirici pozisyonundakiler aynı zamanda eksik gördükleri hususları hızlıca düzeltebilmekte veya yeni özelliklerle desteklemektedirler. Bu modelin kullanıldığı bir alan da coğrafi bilgi sistemleri (CBS) yazılımlarıdır. CBS, coğrafi bilgilerin (objelerin nerede olduğu) onları açıklayıcı bilgilerle (objelerin ne olduğu) ilişkilendiren bilgisayar yazılımlarıdır. Gördükleriminiz nerede olduğunu gösteren düz kağıtların (haritaların) aksine bir çok bilgi katmanı sunabilmektedir. CBS tabanlı bir haritanın kullanımı kağıt bir haritadan çok daha zor değildir. Kağıt haritalarda objeleri temsil eden şekiller, çizimler, temsili geometrik şekiller bulunurken; CBS tabanlı bir haritada da mesela şehirleri temsilen noktalar, yolları ve dereleri temsilen çizgiler, gölleri temsilen poligonlar kullanılmaktadır. Hayatımızın her alanında kullanılan bu nesnelere ait bilgilerin saklanması ve gösterimi de hemen her alanda büyük önem taşımaktadır. QGIS, Open-Source Geospatial Foundation (OSGeo)'a ait dünyanın en popüler ücretsiz coğrafi bilgi sistemleri yazılımıdır. Bu yapının başlıca güçlü yanları olarak eklentiler sayesinde farklı amaçlara dönük araçların oluşturulması ve dahil edilmesi, bunun yanında sürekli büyüyen bir kullanıcı ve geliştirici toğluluğunun bulunmasıdır. QGIS eklenti geliştirme olanakları ve geniş kullanıcı kitlesiyle bu alanda çalışanlara kendilerine ait araçların oluşturulmasına imkan tanımaktadır. Günümüzde QGIS gibi programların lisans veya lisansüstü seviyelerde yalnızca hazır araçlarını kullanıma dönük eğitimler verilmektedir. Halbuki farklı disiplinlerde verilen eğitimlerin teorik bilgisinin yazılımla harmanlanarak ihtiyaçlara dönük hazır araçlar oluşturulması; alınan eğitimleri somut ürünlere dönüştürerek kalıcı hale getirilmesini sağlayacaktır. QGIS bu kapsamda geniş kullanıcı kitlesi, kolay öğrenilebilir ve uygulanabilir geliştirme desteği, kapsamlı uygulama programlama arayüzü (API) dökümanıyla büyük fırsat sağlamaktadır. Bu tez kapsamında CBS eğitiminde eklenti geliştirmenin nasıl ve hangi ortamda oluşturulabileceğine bir örnek hazırlanmış, her eğitim aşamasında bu platformda iyileştirme ve geliştirme yapmak isteyen insanların sürekli desteğiyle yaşayan ve öğreten bir uygulama ortaya çıkması hedeflenmiştir.
Advanced visual odometry and depth estimation techniques for unmanned aerial systems (UAS) in U-Space environments

(Graduate School, 2024-12-11) Roghani Seyed, Seyed Erfan ; Koyuncu, Emre ; 511182113 ; Aeronautical and Astronautical Engineering

This thesis explores advanced techniques in visual odometry (VO) and depth estimation for Unmanned Aerial Systems (UAS), specifically within the context of U-Space environments. U-Space, as a European initiative, aims to ensure the safe, efficient, and secure integration of UAS into airspace. This work contributes to this goal by addressing two critical aspects of UAS navigation: precise visual odometry and reliable depth estimation. Chapter 1 - Introduction: The introduction presents the context of U-Space, outlining its evolution and the services it offers, with a focus on emergency management. The challenges of autonomous contingency planning in UAS operations are highlighted, particularly in relation to visual odometry and depth estimation. Chapter 2 - Canonical Trinocular Feature-Based Visual Odometry: This chapter proposes a novel trinocular camera configuration to enhance VO for UAS. The research compares two trinocular setups—inline and 45-degree—with traditional binocular setups, testing them in various scenarios (horizontal, vertical, hybrid, and long). The results demonstrate that the 45-degree trinocular configuration with a standard lens offers significant improvements in both accuracy and computational efficiency, reducing the computational effort to 40\% of that required by binocular systems while delivering more accurate results. However, when a fisheye lens is used, the benefits are less pronounced, particularly in vertical and long scenarios. Chapter 3 - Fine-Tuning Monocular Depth-Estimator Artificial Neural Networks Trained on Synthetic RGB-D Datasets for Real Scenes: This chapter addresses the challenge of depth estimation for UAS using monocular cameras, which are cost-effective but typically less reliable than stereo cameras. The research investigates the effectiveness of fine-tuning deep-learning models trained on synthetic data with small real-world datasets. The results show that complete fine-tuning of all model parameters, as opposed to just the decoder, yields the best performance, especially when the available real data is limited to less than 12.5\% of the data required for optimal model performance. This finding is crucial for applications where only limited real-world data is available. Conclusion: The thesis concludes that the proposed trinocular VO configuration significantly enhances the accuracy and efficiency of UAS navigation, particularly in complex U-Space environments. Additionally, it establishes the importance of fine-tuning depth estimation models with real-world data, even when such data is scarce, to improve the reliability of UAS in operational scenarios. These advancements contribute to the broader goal of integrating UAS into airspace, ensuring they can operate safely and effectively under various conditions.
Afet bölgelerinde kurulan yerleşim birimlerinin enerji ihtiyacının şebekeden bağımsız hibrit sistemlerle karşılanmasının tekno-ekonomik analizi

(Lisansüstü Eğitim Enstitüsü, 2024-07-22) Yılmaz, Ender ; Çakan, Murat ; 30101014 ; Enerji Bilimi ve Teknoloji

Afet bölgelerinde enerji ihtiyacı afetin gerçekleştiği ilk andan itibaren başlamaktadır. Deprem, sel gibi doğal afetlerden sonra özellikle gece yapılan arama-kurtarma çalışmaları sırasında kullanılacak aydınlatma sistemlerinin ve afetten etkilenen kişiler ve afetin yaşandığı bölge ile iletişimi sağlayacak haberleşme cihazlarının sürekli kullanımda olması gerekmektedir. Ayrıca bölgede kullanılacak sağlık cihazlarının çalıştırılması ve su ihtiyacının karşılanması gibi acil konular da enerji ihtiyacını arttırmaktadır. Doğal afetlerden sonra bölgeye verilen elektrik, doğalgaz gibi yakıtları taşıyan hatlardan sızıntı ihtimaline karşı güvenlik nedeniyle kesilebilir. Afetin verdiği zarardan kaynaklı olarak ise elektrik kesintileri, elektrik hatlarında kablolardaki arızalardan kaynaklanacağı gibi, şehir içi şehirlerarası trafolarda hatta enerji üretim tesislerinde problem oluşabilecek problemlerden de kaynaklanabilir. Bununla beraber doğalgaz, petrol gibi nakil hatlarında problem oluşma ihtimali, ulaşım yollarındaki aksaklıklar, afet sonrası bölgelerde enerjinin yerinde üretilme ihtiyacını gündeme getirecektir. Ayrıca bu uygulama kurulacak bölgede kaçak bağlantıların oluşmasını ve bölgenin şebekeye yük getirmemesinin önüne geçeceği gibi ilerleyen zamanlarda bölgede kurulacak kalıcı konutlarda enerji üretim alt yapısını da sağlayacaktır. Deprem, sel gibi doğal afetler, savaş, zorunlu göç gibi insan ve kıtlık gibi iklim kaynaklı afetlerden sonra insanlar bulundukları bölgeden ayrılmak zorunda kalarak afet bölgelerine yerleşmektedir. Bu bölgelere yerleşen insanların başta barınma, yiyecek ve su gibi önemli ihtiyaçları olmaktadır. Bunun yanında günlük hayatın devamı için önemli olan telefon, tablet ve dizüstü bilgisayarı gibi iletişim araçlarının da elektrik ihtiyacının karşılanması gerekmektedir. Bu ihtiyaçların ilk zamanlarda karşılanmasında portatif ve mobil güneş enerjisi sistemleri kullanılabilmektedir. İlerleyen zamanlarda artan güç ihtiyacı ile beraber daha büyük enerji sistemlerine ihtiyaç vardır. Afet bölgesindeki hanelerde, okul ve sağlık ocağı gibi tesislerde, suyun pompalanması gibi uygulamalarda PV-Bataryalardan oluşan bağımsız güneş enerjisi sistemleri enerji ihtiyacını karşılayabilir. Ayrıca PV-Batarya sistemleri ile bazı afet bölgelerinde insani yardım amaçlı yapılan uygulamalarda bölgenin çok büyük oranda enerjisini üretebilecek kapasitelere ulaşılmaktadır. PV panellerin yanında yoğunlaştırılmış güneş enerjisi özellikle suyun dezenfeksiyonu ve yemek pişirilmesi gibi uygulamalarda kullanılabilmektedir. Rüzgar enerjisi son senelerde gelişen teknolojiyle beraber afet bölgelerinde acil enerji ihtiyacını karşılamakta görev alabilmektedir. Biyogaz bir yenilenebilir enerji kaynağı olarak afet bölgelerinde sanitasyon gibi atık yönetimi uygulamalarından elde edilebilmektedir. Elde edilen biyogaz yemek pişirme için ocaklarda, yüksek miktarda elde edilen biyogaz ise jeneratörlerde enerji kaynağı olarak faydalanılabilmektedir. Afet bölgelerinde bir diğer önemli konuda yemeğin pişirilmesidir, geleneksel yöntemler bırakılarak odun ve odun kömürünü daha verimli kullanan ocaklar, LPG ve etanol ocakları, biyogaz ve solar gibi yenilebilir ocaklar ve son zamanlarda enerji-etkin elektrikli ocaklar bu bölgelerde kullanılabilmektedir. Yenilenebilir enerji kaynaklarının afet bölgelerinde yaygın olarak kullanımını sağlayan en önemli unsur bataryalardır. Özellikle son senelerde düşük güçlerden yüksek güçlere kullanımı yaygınlaşan lityum-iyon bataryalar son dönemlerde öne çıkmaktadır. Dizel jeneratörler afet bölgelerinde enerji ihtiyacını karşılanmasında hala ilk akla gelen yöntemdir. Ancak yakıt masraflarındaki artış ve sürekli yakıt ihtiyacı, emisyon sorunu gibi nedenlerden dolayı afet sonrası alanlarda kullanılması azaltılmaya çalışılmaktadır. Hibrit sistemler yenilenebilir ve dizel jeneratörlerin avantajlarını bir araya getirerek daha güvenilir, sürdürülebilir, emre amadeliği yüksek, uygun maliyetli sistemler olmaktadır. 26 Şubat 2023 günü Kahramanmaraş merkezli iki büyük depremde en büyük yıkımın yaşandığı yerlerin başında Hatay'ın Antakya ilçesi gelmektedir. Depremin özellikle ilk günlerinde başta arama kurtarma çalışmaları olmak üzere bölgede enerji sıkıntısı yaşanmıştır. Bu çalışmada, Antakya ilçesinde afet bölgesinde 72 hanelik bir komşuluk biriminin elektrik ihtiyacı HOMER programı kullanılarak depremin ilk günlerinden başlayarak kademeli olarak yenilenebilir ve hibrit sistemler ile karşılanması planlanmaktadır. Bu plan doğrultusunda enerji ihtiyacının karşılanması için gerçekleştirilecek bu kademeli olarak artış dünya bankası enerji sektörü destek programının hazırladığı SE4ALL (Sustainable energy for all- herkes için sürdürülebilir enerji) çoklu-kademe sistemi bölgeye uyarlanarak yapılacaktır. Afet bölgesinin ilk gününden başlayarak bir haftalık, on beş günlük, üç aylık, altı aylık sürelerde 5 kademe tanımlanmıştır.
Agrivoltaik sistemler ile elektrikli traktörleri şarj etmek için doğru arazilerin saptanması

(Lisansüstü Eğitim Enstitüsü, 2023) Pekdemir, Samed ; Kocaarslan, İlhan ; 800223 ; Enerji Bilim ve Teknoloji Bilim Dalı

İnsanlık çözüm bulamazsa, insanlığın önümüzdeki yıllarda üç büyük zorluk ile karşılaşacaktır. Bu zorluklar gıda kıtlığı, kuraklık ve enerji krizidir. Dikkat ile incelenirse bu zorluklar arasında ayrılmaz bağlar ve nedensellik ilişkileri vardır. Gelecekte şehirleşme, küresel ısınma, iklim değişikliği, hızlı nüfus artışı nedeniyle su, gıda ve enerji kaynakları için rekabet yoğun bir şekilde artacaktır. Fosil yakıtların birincil enerji kaynağı olarak kullanılması, küresel ısınmaya ve iklim değişikliğine önemli ölçüde katkıda bulunmuştur. Bu yenilenemez yakıtların olumsuz çevresel etkileri vardır. Bu sorunlarla mücadele etmek için güneş ve rüzgar enerjisi gibi yenilenebilir enerji kaynaklarının kullanımı artmaktadır. Bu kaynaklar fosil yakıtlara göre daha az zararlı etki üretirken daha fazla arazi alanı gerektirmektedir. Şehirleşme ve artan nüfus da arazi talebini artırarak enerji dönüşümü için gerekli araziye sahip olmayı engelliyor. Tarım ve enerji yakından bağlantılıdır. Tarım endüstrisinde enerji üretme ve tüketme şeklimiz, çevre ve artan nüfusu besleme becerimiz üzerinde önemli bir etkiye sahiptir. Tarım makinelerine güç sağlamak için dizel gibi fosil yakıtların kullanılması çevreye zarar veriyor ve sürdürülebilir değil. Güneş enerjisi üretiminin tarımla entegrasyonu olan "Agrivolaikler" sürdürülebilirliği artırma ve fosil yakıt kullanımının olumsuz etkisini azaltma potansiyeline sahiptir. Elektrikli Traktörler gibi elektrikli araçlar da verimliliği artırabilir ve fosil yakıtlara olan bağımlılığı azaltabilir. Bu teknolojiler, tarım alanlarının korunmasına ve su kıtlığı riskinin azaltılmasına yardımcı olabilir. Son yıllarda, elektrikli traktörlerin benimsenmesi ve agrivoltaik(tarımges) olarak da bilinen fotovoltaik panellerin tarım alanlarına entegrasyonu, çiftçiliğin ve tarım sektöründeki üretimin karbon ayak izini azaltmak ve tarımsal üretimde oluşan enerji talebinin kendi kendine yeterliliğini sağlayan modelleri artırmak için umut verici alternatifler olarak ortaya çıktı. Bununla birlikte, elektrikli traktörlerin ve agrivoltaiklerin yaygın olarak konuşlandırılması, ilgili teknik, ekonomik ve çevresel faktörlerin kapsamlı bir şekilde anlaşılmasını gerektirmektedir. Bu yüksek lisans tezi, Coğrafi Bilgi Sistemleri (GIS), parçacık sürüsü optimizasyonu ve k-means kümeleme kullanarak elektrikli traktörlerin ve agrivoltaiklerin belirli bir tarımsal bağlamda uygulanmasının fizibilitesini değerlendirmek için bir metodoloji geliştirmeyi amaçlamaktadır. Çalışmada kışlık buğday ekimi ve güneş enerjisi üretimine odaklanılmıştır. Çalışma ayrıca elektrikli traktörlerin ve agrivoltaiklerin potansiyel faydalarını ve zorluklarını değerlendirmek için arazi, hava durumu ve yenilenebilir kaynaklar hakkındaki verileri içermektedir. Ayrıca bu teknolojilerin ve modelin tarım sektöründe uygulanmasına yönelik öneriler sunulacaktır. Bu bağlamda bu çalışmada, K-means ve parçacık sürü optimizasyonu (PSO) kullanılarak bir güneş enerjisi santralinin arazide en uygun yerini belirlemek için bir hibrit optimizasyon modeli geliştirilmiştir. Bu yaklaşımın amacı, fotovoltaik güç çıkışını en üst düzeye çıkarmak ve elektrikli traktörler gibi elektrikli tarım makinelerinin yeterince şarj edilmesini sağlamaktır. Bu modelin kullanılması tarım endüstrisinin verimliliğini ve sürdürülebilirliğini artırmaya yardımcı olabilir. Bu çalışmada, öklid mesafesine dayalı parsel kümeleri oluşturmak için K-means algoritması kullanılmıştır. Parçacık sürüsü optimizasyonu (PSO) algoritması daha sonra bir amaç fonksiyonuna dayalı olarak en uygun parseli bulmak için kullanılır. İlk iterasyonda enerji talebi karşılanmazsa, küme sayısı birer birer artırılır ve yeni optimal parseller aramak için PSO kullanılır. Bu işlem, hesaplanan enerji talebi seçilen parseller tarafından karşılanıncaya kadar tekrarlanır. Algoritma tarafından bulunan optimum parselde üretilebilecek güneş enerjisi miktarını dünya çapında çoğu yer için bu bilgileri sağlayan bir web uygulaması olan PVGIS'ten gelen güneş radyasyonu ve fotovoltaik (PV) sistem enerji üretim verileri kullanılarak bulunur. Daha gerçekçi sonuçlar elde etmek için gerçek parsel verileri kullanılmıştır. Çalışmada kullanılan veriler TKGM (Türkiye Tapu Ve Kadastro Genel Müdürlüğü) web sitesi kazınarak elde edilmiştir. Çalışmada kullanılan parsel verileri Büyüköz (Ahirli/Konya'da bulunan bir köy), Karkin ve Üçhüyük'e (Çumra/Konya'da bulunan iki köy) aittir. Bu çalışmada bir alanın enerji talebini belirlemek için Avustralya'daki Yeni Güney Galler eyaleti hükümeti, yanlış traktörün kullanılması yakıt israfına ve erken arızalara neden olabileceğinden, çiftçilere arazileri ve mahsulleri için uygun güçte traktörleri seçmelerine yardımcı olan klavuzdan yararlanılarak oluşturulmuştur. Algoritmadan beklentilere ve içgüdüye uygun sonuçlar elde edildi. Fakat bu çalışmanın en önemli çıktısı olarak, elektrikli traktörün enerji talebi, kullanılan ekipman sayısı ve tipini etkilediğinden dolayı yetiştirilen ürünlere bağlı olarak değişeceğindan dolayı planlamanın tarımda özellikle enerji tüketimi ve üretimi için kritik öneme sahip olduğunu sonucuna da varılmıştır.
Air-Sea Interactions in the Formation of Thunderstorms over Marmara Region: Physical Processes and Modelling

(Graduate School, 2022-10-28) Yavuz, Veli ; Deniz, Ali ; 511162006 ; Atmospheric Sciences

Thunderstorm and sea-effect snow (SES) are meteorological events that adversely affect both daily life and the transportation sector, and occur as a result of air-sea interaction. Thunderstorm, is a meteorological phenomenon that usually contains strong winds and causes strong precipitation (e.g., rain, hail) accompanied by lightning. Intense atmospheric instability, high humidity, vertical triggering mechanisms, and wind shears are essential components for thunderstorm formation. Thunderstorms caused by cumulonimbus clouds occur both with precipitation and without precipitation. On the other hand, they occur not only with rain, but also with snow and hail. This phenomenon, known as a severe weather event, occurs as a result of convectional movements. For this reason, the increasing differences between the upper atmospheric level air parcel temperature and the sea or lake surface temperatures play an intensifying role in thunderstorm activities. SES occurs as a result of atmospheric instability, which occurs as a result of dry and cold air masses gaining heat and moisture fluxes as they pass over warmer water bodies. As a result of the instability of very cold and dry air parcels of arctic or polar origin during their passage over the Black Sea located in the north of our country, the Marmara Region and the Black Sea Region are exposed to SES in the winter months. Although SES cause heavy snowfalls in regions where they are effective as severe weather events, they do not need synoptic-scale systems to occur. SES that occur in a region where synoptic-scale systems are currently dominant are called as snowfall with increased sea effect. This type of snowfall causes more intense snow on the regions where the SES bands pass. In our country, there are studies on both severe weather events mentioned above. There are both case studies and climatological analyses in the literature regarding the thunderstorm event. However, climatological analyses and short-term forecast models are limited in terms of their effects on the Marmara Region and especially on the aviation sector. On the other hand, there are a very limited number of studies in the literature regarding the SES events for our country. There is no climatological comprehensive analysis or a prediction mechanism established for certain sectors for this event, where only a few assessments and case studies are included in the international literature. Both a knowledge and a scientific base are needed for this severe weather event, which is very effective in the northern parts of our country during the winter months and directly affects both daily life and transportation activities. In this context, in this thesis, a total of nine articles, two on thunderstorm events and seven articles on SES, were published in six different internationally refereed journals. In the first article, a short-term forecast of the thunderstorm that occurred at Istanbul Atatürk International Airport on February 2, 2015 was made. It has been determined that the thunderstorm and its severity can be predicted in the range of 42-57 minutes in advance by analysing radar images, Lightning Detection Tracking System (LDTS), sea surface temperature information, and surface/upper level atmospheric information. It has been revealed that this result is important for the decision makers working in the meteorology office. In the second article, various 15-year long-term statistics of thunderstorm events were investigated at 11 airports in the Marmara Region. Atmospheric conditions in which thunderstorm events occur and the effects of air-sea interaction were examined. Intraday, monthly, and annual distributions were analszed. No trend was determined on an annual basis, and the most observations were made in September on a monthly basis. In the daytime thunderstorm distribution, the most observations occurred between 1100-1900 hours. 72% of thunderstorms occurred with rain and 22% without any precipitation. One of the most important results of the study is that the Convective Available Potential Energy (CAPE) is zero in approximately 50% of the events. In the third article, the morphological classification of SES bands was made for the Danube Sea Area (western Black Sea) in the Black Sea. Between 2009 and 2018, SES bands were observed over the region in a total of 83 days, and these bands caused snowfall within the borders of the Marmara Region in 75 days. Various satellite and radar images obtained from the Turkish State Meteorological Service (TSMS) were used for the detection of SES bands. In total, five different types of SES bands have been defined for the region. The most common type of band among all events was Type-2 SES band with 85%. The most important reason for this is that this band type consists of parallel bands in the longitudinal direction. The north-south movements of polar and arctic air masses along the long fetch distance of the western Black Sea have created suitable atmospheric conditions for the Type-2 band. On average, the lowest sea surface temperatures (SESs) occurred in the northernmost part of the Danube Sea Area. This region is the region where SES bands mostly begin to form and are of weak intensity. The intensity of the bands increased due to the increasing SST towards the south. In the fourth article, the analysis of vortex (Type-5) SES bands that occurred in the western Black Sea on January 30-31, 2012 was carried out. The vortex band, which was detected with various images of two different satellites (Terra and MSG satellites), continued its effect on the region for approximately 24 hours. The structure of the vortex was analysed by analysing the surface level meteorological data obtained from 12 airports, 16 meteorological stations, and 5 radiosonde stations belonging to the countries surrounding the western Black Sea and various charts of the upper atmospheric levels. The 24 cm of snow depth was measured at the İnebolu meteorology station, where the SES bands connected to the vortex were effective, and a total of 102 flights were canceled across the countries surrounding the western Black Sea. In addition to these, many traffic accidents have also occurred due to heavy and sudden snowfalls. The surface and upper level atmospheric conditions that create the vortex were found as follows: presence of a strong/deep inversion layer between the surface and 700 hPa, the wind direction change being limited to a maximum of 50° in the same vertical range, the temperature difference reaches 25.8 °C in between the sea surface and 850 hPa at the point where the vortex core is located. In addition, in the analyses made with the synoptic charts, it was determined that the vortex was formed during the two-day period and there was a low pressure centre in the region where the core is located. In the fifth article, the statistical characteristics of SES events for the western Black Sea were analysed for the years 2009-2018. The main purpose of the study is to determine the meso- and synoptic-scale structures of SES events for the region in general and to create knowledge for nowcasting and forecasting applications to be made later. A total of 95 events were detected using satellite and radar images. These events were determined according to four different scale categories. As a result, 36 events (38%) are determined as Black Sea (BS) Events, 24 (25%) as Synoptic-scale (SYNOP) Events, 23 (24%) as Over Sea Convergence (OSC) Events, and 12 (13%) as Transition (TRANS) Events. While the average duration of SES events in four different categories was 15.9 hours, the longest time was 59 hours in the SYNOP Events. Except for the OSC Events, the prevailing wind direction under the inversion layer was northerly in all three categories. Inversion layer was detected in most of the BS Events and SYNOP Events, and the sea surface and upper level temperature difference was 4 °C to 6 °C higher on average compared to the other two categories. The highest number of events occurred in January with 51, and the lowest in March with 2. In the sixth article, the effect of short-wave troughs on the formation and development of SES bands in the western Black Sea was investigated. Between 2010 and 2018, a total of 48 short-wave troughs and long waves were detected in the presence of SES bands throughout the region. The most important role of long waves has been realized as a result of determining the direction of short-wave troughs. Afterwards, short-wave troughs and long waves were classified based on their direction of motion. Five different types of short-wave troughs and five different types of long waves were determined, and their monthly and annual statistics, and their durations were revealed. In addition, the temperature differences between sea surface and upper atmospheric levels were analysed for each type, and inversion conditions were examined. The average duration of short-wave troughs was found to be 27.8 hours, and the longest time was observed in LWT type with 60 hours. In 77% and 79% of all events, respectively, short-wave troughs and long waves were found to have the same direction of motion as the current SES bands. In the seventh article, thundersnows occurring in the Marmara Region within a 22-year period were investigated. For these events, the formation mechanisms, suitable surface, sea, and upper level atmospheric conditions were investigated. Based on the reports of 11 airports in the region, a total of 19 incidents were identified. In 17 of these events, the SES mechanism was found to be effective. After statistical temporal analysis, the predictability of these events was investigated with atmospheric stability indices. Accordingly, the most successful stability indices were Total Total Index and TQ Index. In the eighth article, a comparison of SES and non-SES for two international airports in Istanbul is made. A SES event prediction algorithm was developed for both airports using 10 years of atmospheric data. At the same time, suitable atmospheric conditions were determined according to the snow depths. Finally, in the ninth article, historical extreme winters in Istanbul were investigated. The events that took place within the scope of the 17-century period are shown, and based on the events that took place in the last few centuries, heavy snowfall and harsh winter forecasts are made for the period up to 2050 and 2100.
Aircraft trajectory optimization under wind effect by using optimal control : Environmental impact assessment

(Graduate School, 2022) Sezenoğlu, Fulin ; Özkol, İbrahim ; Defence Technologies Programme

The aim of this thesis, Aircraft Trajectory Optimization Under Wind by Using Optimal Control and Environmental Impact of Aviation in terms of Aircraft Emissions, is to find the wind and weather optimized aircraft trajectories in the cruise phase by minimizing fuel consumption, time and air pollutants. Flight trajectories calculated by taking into account the wind factor are considered as a critical measure in terms of reducing fuel consumption. In addition, it is known that the models examined by including weather information give more realistic results than those that are not included. Trajectory planning calculations consist of various elements such as wind forecasts, operational constraints, amount of fuel, aircraft performance, atmospheric conditions. Temperature, pressure and air density parameters are considered standard atmospheric values. The performance model used is based on BADA. In order to achieve the aims of the thesis, first of all, the problem has been tried in 2 dimensions in terms of reducing complexity of operations. At this stage, the wind equation, which was created with a simple calculation, was added to the EoM in horizontal plane. The effect of the horizontal components of wind is clearly seen in the numerical simulation. Secondly, the problem was created according to BADA 3 and solved in a way that minimizes flight time and fuel in 3 dimensional space. Simultaneously, a wind model has been created with the wind tabular data obtained from the Global Forecast System (GFS). The GFS is a weather forecast model developed by the National Centers for Environmental Prediction (NCEP). In this study, wind factor was assumed to be stationary, wind uncertainty was not included in this study. Since there are erroneous measurements in the wind tabular data obtained from the Global Forecasting System (GFS), the data was improved by applying the interpolation method first and the error difference between the real data and the interpolated data was arranged to be the least. Then, with the smooth data, wind equations were obtained separately for seven barometric altitude levels. Thirdly, in addition to flight time and fuel consumption, an emission model was created based on the ICAO Engine Exhaust Data Bank [29] and Boeing Method 2 [30] to solve the multi-objective optimization problem. The developed new model was applied to the simulation environment created based on BADA 4. Finally, the wind equations in the horizontal plane obtained were included in the simulation environment developed on the basis of BADA 4, and the targeted model was created. Predetermined routes were filtered from the actual flight plan selected for the same day with the wind data to be examined in the case studies. The flight area was determined and a wind model was obtained for that region. All one-day flights for the selected route were examined. Wind equations are calculated by taking flight hours into account. The simulation results were obtained according to the flight information of the desired route obtained from the real flight plan. The optimized trajectories were calculated in the simulation environment by referring to the points where the aircraft started and ended the cruise phase. Thus, Turkish airspace, which has not been examined before, is presented as a case study specific to Istanbul-Ankara flights. As a second case study, European airspace is presented specific to Paris-Frankfurt flights. During these studies, it was clearly seen that cruising speed and cruising altitude are critical for fuel consumption under the wind effect. In addition, as a result of these studies, it has been shown that the proposed model gives more effective results as the flight distance increases. This study consists of five chapters describing the stages of the thesis. The first chapter is a general introduction to the thesis topic. The thesis topic is explained and its aims are mentioned, the importance of the subject and why it is needed are presented. This section consists of three sub-titles. First of all, the scope and contributions of the thesis are mentioned. Afterwards, a wide literature review was made and studies in this field were presented. Finally, the structure of the thesis is mentioned. In the second chapter, the mathematical model required for this study is explained. Wind-optimized trajectories for an aircraft in the cruise phase are generated by solving a non-linear optimal control problem. For this reason, first of all, the general representation of the optimal control problem and its solution techniques are mentioned. The suitability of these solution techniques to the problem is discussed and the method to solve the problem is explained. It is known that multi-objective optimization problems give more realistic and ideal results than single-objective optimization problems. After this part, multi-objective optimization problem and constraints are defined. In the last part, the optimal control problem solution method is mentioned. GEKKO Python optimization module was used for numerical simulation in solving the aircraft trajectory optimization problem. This algorithm was developed to analyze the environmental impact of emitted aircraft emissions such as nitrogen oxides and carbon dioxide, using real air traffic data. In the third chapter, models used in trajectory generation optimized for wind and weather conditions are introduced. First, the assumptions are mentioned. Afterwards, the atmosphere model, aircraft performance model, wind model and emission model are explained in detail. In addition, the equations of motion of the aircraft in 2D and 3D are shown in this section. In the fourth chapter, two case studies on the subject and their results are presented. First of all, it is the main contribution to the literature to analyze the flights over Turkey, which has not been focused on before as a case study. First, the problem is defined in the case analysis. Then, the wind field over the Turkish airspace was examined and a wind model was created. The wind equations of the region, which was extracted to include Istanbul and Ankara, were obtained and added to the equations of motion of an aircraft, as explained in wind model section in third chapter. In the simulation environment created in this direction, the most optimized trajectories were calculated considering the Istanbul-Ankara flights. As the second case study, Paris-Frankfurt flights over European airspace were analyzed. As in the first application, after defining the problem respectively and examining the wind field covering the flight points, the multi-objective optimization problem was solved for this route. As a result of the case studies, the actual and calculated flight time, fuel consumption, NOx and CO2 emission findings for each flight are presented comparatively. In the fifth and also the last chapter, the results and other studies that can be done in this field are mentioned. The values obtained as a result of the case analyzes are emphasized again. Within the scope of the study, it has been shown that the adverse impacts of aviation on the climate are reduced by trajectory optimization, which is resolved by evaluating wind and environmental effects. The topics that can be studied on the basis of this study in the future are mentioned.
Aladağlar ve Karanfil Dağı kuvaterner buzullaşması ve eski ikliminin kozmojenik izotoplar ve buzul modelleri ile belirlenmesi

(Lisansüstü Eğitim Enstitüsü, 2023-06-06) Köse, Oğuzhan ; Sarıkaya, Mehmet Akif ; 602172004 ; Jeodinamik

Orta Toroslar'ın en büyük kütlesini oluşturan Aladağlar ve yaklaşık 10 km güneyinde bulunan Karanfil Dağı bu çalışmanın inceleme alanını oluşturmaktadır. Çalışma alanı temelde karbonatlı kayaçlardan oluştuğundan, bu bölgedeki akarsular mevsimlik akarsu özelliğine sahiptir. Bu durum buzul süreçleri sonrasında akarsuların gelişmesini engeleyerek Karanfil Dağı ve Aladağlar'da buzul vadilerinin ve morenlerin korunmasını sağlamıştır. Ayrıca, çalışma alanı jeolojik ve tektonik özelliklerinin yanı sıra buzul ve akarsu süreçleri ile karstik süreçler arasındaki etkileşimin anlaşılması için örnek bir topoğrafya sunmaktadır. Jeomorfolojik çalışmalar kapsamında arazi çalışmaları ve uzaktan algılama yöntemleri kullanılarak çalışma alanının buzul jeomorfoloji haritası üretilmiştir. Bölgenin 1:50.000 ölçekli buzul jeomorfoloji haritası oluşturulmuş, buzul vadileri, sirkler, arêtler ve piramidal zirveler, döküntü ile örtülü buzullar, morenler ve sandur depoları belirlenmiştir. Kozmojenik 36Cl yüzey tarihlendirme yöntemiyle ana kaya ve morenler üzerinden toplam 121 adet örnek toplanarak Aladağlar ve Karanfil Dağı'nda geçmişte buzulların oluşturduğu yer şekilleri tarihlendirilmiştir. Karanfil Dağı SBM dönemi buzul koşullarını anlamak amacıyla üç boyutlu bir fiziksel buzul akış modeli (PISM) kullanılmıştır. Farklı sıcaklık ve yağış değerleri kullanılarak 21 farklı paleoiklim simülasyonu üretilmiştir. Bu paleoiklim simülasyonları arazi gözlemleriyle karşılaştırılmıştır. Aladağlar'da 47 ve 38 bin yıl öncesine dayanan en yaşlı morenler, dağın batı-kuzeybatısında bulunan Körmenlik ve Maden vadilerine aittir. Körmenlik vadisinin çıkışında bulunan Sulucaova sanduru ise 79 bin yıl öncesine ait buzullaşmanın varlığını göstermektedir. Körmenlik ve Maden vadilerinden elde edilen kozmojenik tarihlendirme sonuçları SBM öncesini, MIS 3 sırasındaki buzul geri çekilmesinin kanıtlarını sunmaktadır. Önceki çalışmalar kapsamında Yedigöller Platosu'nun kuzey sınırını çizen Akçay Sırtı'ndan elde edilen ana kaya yaşları tekrar hesaplanmıştır. Elde edilen sonuçlar 3500 metre yükseklikte bulunan Akçay Sırtı'nın en az 55.2 ± 12.0 bin yıldan beri buzullarla kaplı olmadığını göstermektedir. Bu bulgu, Yedigöller Platosu'ndaki buz örtüsünün 3500 m yüksekliklere kadar ulaşmadığını açıkça ortaya koymaktadır. Ayrıca, Kemikli Vadisi'nin yukarı çığırında, 3200 metre yükseklikteki Akçay Platosu'ndan alınan ana kaya örnekleri de bölgenin 76.7 ± 23.8 bin yıldan beri buzullarla kaplı olmadığını göstermektedir. Aladağlar'ın doğusunda bulunan Hacer Vadisi ise en uzun buzulun geri çekildiği alan olup buzulun geri çekilme süreci 15 bin ile 12.5 bin yıl öncesine kadar devam etmiştir. Bu geri çekilme, Geç Buzul döneminden Genç Dryas dönemine kadar olan buzullaşmanın varlığını göstermektedir. Aladağlar'ın doğusunda bulunan Susuz ve Sineklikapız Vadileri'nden de Erken Holosene ait kozmojenik tarihlendirme xxii sonuçları elde edilmiştir. Aladağlar'da buzullar, 55 bin yıl önce en yüksek zirvelerden geri çekilmeye başlamış olup Holosen döneminin başlangıcına kadar iki takke buzulu aktif kalmıştır. Karanfil Dağı'nın ilk buzul jeomorfoloji haritası ve Kozmojenik 36Cl buzul kronolojisi bu çalışmada sunulmuştur. Buzul yer şekilleri arasında sirkler ve morenler detaylı bir şekilde haritalanmıştır. Dağın kuzey yamacında bulunan 2000-2400 m yüksekliğe sahip ve 1-2 km uzunluğunda iyi korunmuş dört terminal ve yanal moren seti (M1, M2, M3 ve M4) detaylı bir şekilde haritalanmış ve tarihlendirilmiştir. M1 (17.3 ± 2.4 bin yıl), M2 (18.6 ± 1.6 bin yıl) ve M3 (20.0 ± 2.6 bin yıl) morenlerinin ortalama yaşları, Karanfil Dağı'ndaki buzulların SBM sırasında maksimum boyutlarına ulaştığını göstermektedir. M4 moreni, daha kuzeye bakan ve korunaklı bir sirke sahip olup, moren yaşı14.6 ± 2.4 bin yıl olarak ölçülmüştür. M4'ten elde edilen ortalama yer şekli yaşı, M4 buzulunun Geç Buzul dönemine kadar varlığını sürdürdüğünü (16-20 bin yıl arasında) göstermektedir. C1 sirk tabanındaki kalıntı kaya buzulunun yaşı ise (9.9 ± 0.9 bin yıl) Holosen başlangıcındaki permafrost koşullarının varlığını kanıtlamaktadır. Karanfil Dağı'nda SBM buzullarını oluşturan iklim koşullarını anlamak için üç boyutlu fiziksel PISM buzul akış modeli çalıştırılmış ve 21 farklı simülasyon üretilmiştir. Karanfil Dağı için en uygun model sonuçları, SBM'deki buzulların günümüze benzer yağışlar altında oluşabilmesi için sıcaklık düşüşünün günümüzden 8.3 ± 0.5 °C daha fazla olduğu bir iklimi göstermektedir. SBM döneminin günümüze göre %20 daha nemli iklim koşullarına sahip olması durumunda, SBM buzullarının oluşabilmesi için gereken sıcaklık düşüşü 6.9 ± 0.4 °C olarak hesaplanırken, %20 daha kurak iklim koşullarında ise bu sıcaklık düşüşünün 10.4 ± 0.6 °C olması gerektiği hesaplanmıştır.
Alkylacrylamide-based semi-interpenetrating networks for temperature-sensitive smart systems

(Graduate School, 2022-06-15) Kalkan, Birgül ; Orakdöğen, Nermin ; 509201205 ; Chemistry

Hybrid gels containing nanoparticles offer opportunities to selectively tailor the final properties as desired. Novel approaches in design of hybrid gel systems have led to the design of high-performance complex materials. These alternative preparation approaches focus on tuning the required functional and structural properties with a new material structure. Within the scope of this thesis, semi-IPN structures containing linear polymer polyacrylamide (PAAm) chains in different amounts were firstly prepared. The temperature sensitive monomer N-isopropylacrylamide (NIPA) was used as the main monomer, and a series of temperature and pH sensitive gels in the form of semi-interpenetrating polymer network (semi-IPN) structures were prepared by adding Methacrylic acid (MA) comonomer. In the second part of the thesis, the semi-IPN gel composition with the optimum structure obtained from the first part was selected and a semi-IPN structure hybrid gel synthesis was carried out by incorporation of different amounts of silica particles. In the first part of the experimental work of this thesis, a series of thermoresponsive semi-IPN gels based on linear polymer PAAm, NIPA and MA were synthesized by varying the linear polymer content via free radical polymerization. An interpenetrated network of P(NIPA-MA)/PAAm was designed to modulate elasticity by varying inner composition and to improve rate of swelling-deswelling phenomenon. The correlation between swelling and compression elasticity was demonstrated. The inclusion of linear PAAm chains into P(NIPA-MA) network induced physical entanglements, increased apparent crosslinking density and enlarged the compressive elasticity. The dependence of apparent crosslinking density on the linear polymer content was expressed as a cubic polynomial function. The extent of swelling of semi-IPN P(NIPA-MA)/PAAm gels was sensitive to presence of linear PAAm chains. The existence of linear polymer decreased apparent ionic group density and increased the crosslinking density compared to that of copolymer P(NIPA-MA) network which in turn decreased the equilibrium swelling. A significant increase in the swelling/shrinking rate was observed in the presence of linear PAAm. Due to ionization of carboxylic acid groups in P(NIPA-MA) network, semi-IPN P(NIPA-MA)/PAAm gels showed different degrees of swelling depending on linear PAAm content and temperature of swelling medium. Semi-IPNs exhibited phase transition temperatures shifted higher temperature, suggesting physical entanglements between P(NIPA-MA) network and linear PAAm. An increase in the swelling temperature resulted in an increase in Flory-Huggins interaction parameter. The entropic contribution increased and the enthalpic contribution decreased with PAAm content. In the second part of the experimental work of this thesis, a series of semi-IPN P(NIPA-MA)/PAAm hybrid gels reinforced with silica particles (SiP) were designed by incorporation of linear PAAm chains. Formation of temperature-sensitive hybrid semi-IPN gels was evaluated by simultaneous radical polymerization under warm and cold conditions, and the role of polymer/particle interfaces in the elasticity of hybrid gels was explained. Nanoparticle-mediated enhancements were studied to understand the effect of SiP added to anionically modified semi-IPNs. The formation of hybrid network was confirmed by FTIR and an increase in the amount of SiP led to enhanced Si-O-Si absorption peak in the hybrid samples. P(NIPA-MA)/PAAm/SiP gels displayed a decrease of swelling with increasing amount of SiP. Flory-Huggins parameter of interaction of SiP-loaded semi-IPN hybrid-solvent were estimated using the extended equation. The compressive testing results showed an improvement in the stiffness and modulus attributed to transference of stress from the hybrid to the nanoparticles. The swelling processes of SiP-loaded semi-IPN hybrids obtained by cold polymerization are anomalous diffusion owing to polymer relaxation, while Fickian behavior was observed for the gels obtained by warm polymerization. During oscillation shrinking-swelling of SiP-loaded semi-IPN hybrids upon ionic-strength switching in NaCl solutions, the gels retained their shape and integrity for 10 cycles of measurement. The effect of changes in solution environment on the swelling and elastic properties of SiP-loaded semi-IPN hybrids was investigated. Sodium salts of CH3COO−(Ac), NO3−, and SCN− were employed to understand specific ion effects and to gain an insight into the influence of kosmotrope and chaotrope solutes on the swelling and elasticity at various ionic strength and temperature. The identity of counterion had a strong influence on swelling and compression modulus and was found to follow the reverse order of classical Hofmeister series (HS). The phase transition temperature decreased with increasing salt concentration, and transition changed from discontiuous to continuous. At low salt concentrations, the gels showed discontinuous phase transition at 50 oC, while the transition temperature shifts towards 35-45 oC with increasing salt concentration. Dilution of the solution to 10-3 M resulted in a 2.0-fold reduction in the compressive modulus of hybrid gels in NaAc solutions while a 3.0-fold reduction in NaSCN solutions. The compression modulus increased with shrinkage of hybrids due to increasing salt concentration. The effect of pH change of swelling medium on the swelling, phase transition profile and elasticity was evaluated. The continuity of pH-dependent swelling curve depended on the swelling temperature. pH-triggered oscillation kinetics have been investigated to understand whether they can be used as a pH oscillator since the phase transition pH is close to 5.7. The swelling of SiP-loaded hybrids followed a Fickian type diffusion. To evaluate the adsorption characteristics of SiP-loaded semi-IPN hybrids, methyl violet (MV) was chosen as model cationic dye. The effects of contact time, silica content and initial dye concentration were studied. The time-dependent adsorption data was fitted with six kinetic models. MV uptake capacity of SiP-loaded semi-IPN hybrids increased with an increase in initial MV concentration as well as with silica content. The adsorption process followed pseudo-second order type adsorption kinetics and the mechanism of process was better described by intraparticle difusion. Different adsorption isotherm models were investigated to describe interfacial adsorption of MV which was strongly dependent on compositions of hybrids. Langmuir isotherm model was found to be most appropriate to describe adsorption process. The superior properties imparted to the present system prepared with anionic modification, semi-IPN structure and SiP-loading make semi-IPN hybrid gels suitable candidates for controlled release systems and for adsorbents of cationic dyes.
Altlığın temassız ısıtılması yöntemi ile geniş yüzeylerde zeolit kaplamaların hazırlanması ve karakterizasyonu

(Lisansüstü Eğitim Enstitüsü, 2023-01-16) Maraş, Taylan ; Erdem, Ayşe ; 506152006 ; Kimya Mühendisliği

Zeolitler, moleküler boyutta gözenek ve/veya kanallar içeren, kristal yapılı, sulu alüminosilikat mineralleridir. Doğada bulunabilen çeşitlerinden sayıca çok daha fazlası laboratuvarlarda sentetik olarak da üretilebilmektedir. Moleküler elek özellikleri, geniş yüzey alanları, yüksek boşluk hacimleri ve sulu çözeltilerde değiştirilebilen, kafes yapısına katılmamış iyonlara sahip olmaları gibi nedenlerle, zeolitler endüstride adsorban, katalizör ve iyon değiştirici olarak çeşitli uygulamalarda sıkça tercih edilmektedirler. Zeolit kaplamalar, zeolit kristallerinin bir yüzeye kimyasal ve/veya fiziksel bağ ile bağlanmasıyla oluşan kompozit malzemelerdir. Zeolitlerin kaplama formunda kullanılmaları, toz ve pelet formunda kullanımlarına kıyasla, çeşitli uygulamalarda daha iyi ısı ve kütle iletimi sağladığı için tercih edilmektedir. Çeşitli membran ayırma ve algılama (sensing) uygulamalarındaki potansiyel kullanımları açısından da giderek önem kazanmakta olan zeolit kaplamalar, zeolit sentezi sonrasında kristallerin bir bağlayıcı ya da fiziksel bağ ile altlık yüzeyine tutunmasıyla hazırlanabildiği gibi, zeolitlerin doğrudan altlık üzerinde kristalizasyonu ile de üretilebilmektedir. Zeolit sentezi sonrasına dayanan yöntemlerde, bağlayıcı kullanıldığı durumda yüksek kalınlığa sahip kaplamalar elde edilmesine karşın, kaplamaların yeterince yüksek ısı iletim ve difüzyon katsayısına sahip olmamaları, bağlayıcının adsorpsiyon kapasitesini ve ölü ağırlık yaratarak verimi düşürmesi gibi sorunlarla karşılaşılmaktadır. Zeolitin doğrudan altlık yüzeyinde kristalizasyonu ile elde edilen kaplamalar kullanıldığında ısı ve kütle iletiminin iyileştirilebildiği görülmüştür. Ancak bu yöntemlerin de, kaplamaların sentezi sırasında çözelti içinde kristalizasyon gerçekleşmesi nedeniyle kaplama kalınlığının düşük olması, uzun sentez sürelerinde faz transformasyonu görülmesi gibi dezavantajları vardır. Literatürde önceki çalışmalarda altlığın daha yüksek sıcaklıklarda, sentez çözeltisinin ise daha düşük sıcaklıklarda tutulduğu, altlığın ısıtılması yoluyla kaplama yöntemi kullanılarak sözü geçen dezavantajların azaltıldığı görülmüştür. Bu tezde yeni geliştirilmiş olan indüksiyon yöntemi kullanılarak altlığın uzaktan, temassız ısıtılması yoluyla geniş yüzeylerde nem tutma uygulamaları için yeterince kalın, kristalin ve dayanıklı zeolit kaplamaların hazırlanması amaçlanmıştır. Elde edilen kaplamalar TGA, XRD ve SEM yöntemleri ile karakterize edilmiştir. Zeolit kaplamaların hazırlanabilmesi için ana parçaları indüksiyon ısıtıcı, reaktör, pompa ve ısı değiştirici olan bir sistem kurulmuştur. Öncelikle, önerilen yöntemin altlığın sentez çözeltisi içine daldırılmasına dayanan geleneksel kaplama yöntemi ile farkı araştırılmıştır. Geleneksel kaplama yöntemi ile geniş yüzeylerde elde edilen kaplamaların kristalin olmasına karşın, düşük kalınlığa, homojenliğe ve dayanıklılığa sahip olduğu görülmüştür. İndüksiyon ısıtma yöntemi ile 2 saat gibi kısa sentez süresinde dahi, geleneksel yöntemde 48 saatte hazırlanan kaplamanın 1,5 katı kalınlıkta kaplama elde edilmiştir. Ayrıca kaplamanın yüksek kristaliniteye ve homojenliğe sahip olduğu görülmüştür. İndüksiyon ısıtma yönteminin, altlığın ve çözeltinin hızlı ısıtılması, çözelti içindeki kristalizasyonun baskılanması gibi nedenlerle kaplama birikme ve kristalizasyon hızında önemli avantajlar sağladığı görülmüştür. Deneysel çalışmanın bir sonraki aşamasında, kaplamaların kristalinitelerinin, kalınlıklarının, homojenliklerinin ve içerdikleri fazların reaktör giriş-çıkış sıcaklıkları ve bu sıcaklıklar arasındaki fark ile değişimi incelenmiştir. Bu amaçla indüksiyon gücü, kreostat sıcaklığı ve sirkülasyon debisi değerleri kontrol edilerek, farklı sentez sıcaklık ve sürelerinde deneyler yapılmıştır. Deneysel parametrelere bağlı olarak değişen bir başka önemli parametre olan altlık yüzey sıcaklığının kaplama özellikleri ile ilişkisi de izlenmiştir. Seçilen deney koşulları aralığında, reaktör giriş-çıkış sıcaklıkları arasındaki fark sabit tutularak sıcaklıklar arttırıldığında kaplama kalınlığının ve kristalizasyon hızının arttığı görülmüştür. Öte yandan, sıcaklıklar arttığında, sentez süresi arttıkça sınırlayıcı reaktan miktarının azalmasına bağlı olarak kristalizasyon hızının amorf madde birikme hızının gerisinde kaldığı ve faz transformasyonlarının başladığı görülmüştür. Bu nedenle de kristalinite zamanla azalmıştır. Reaktör giriş-çıkış sıcaklıkları arasındaki fark giriş sıcaklığı arttırılarak düşürüldüğünde kaplama kalınlığı azalırken kristalitenin arttığı ve faz transformasyonlarının ötelendiği gözlenmiştir. İndüksiyon ısıtma yöntemi ile elde edilen kaplamaların ısıl ve mekanik dayanımları ile desorpsiyon kinetiklerini incelemek adına tekrarlı sentezler ile elek, boru ve boru üstü elek altlıklar üzerinde kütlece eşdeğer kalınlıkları 1,2 mm'ye ulaşan ve esas olarak NaX'ten oluşan kaplamalar hazırlanmıştır. Dayanıklılığı arttırmak için sentez sonrasında kaplamalar polimer ile kaplanmıştır. Çift katlı elek ve boru üstüne kaynatılmış çift katlı elek altlıklar üzerinde hazırlanan kaplamaların ısıl ve mekanik dayanımlarının yüksek olduğu, boru altlıklar üzerinde elde edilen kaplamaların ise ısıl test sırasında döküldüğü görülmüştür. Altlıklarda elek kullanımının kaplama dayanıklılığını arttırdığı gözlenmiştir. SEM görüntüleri, kristallerin tellerin üzerinde sıkı şekilde büyüdüğünü ve tel açıklıklarının zeolit kaplamasının yoğun bir tabaka şeklinde değil, açık ve süngerimsi bir yapıda büyümesine yardımcı olduğunu göstermiştir. Metal elekler üzerindeki kaplamaların desorpsiyon kinetiklerinin, benzer metal eleklerden yapılmış petri kabı içindeki toz zeolit örneği ile karşılaştırıldığı durumda, ilk 5 dakikada 3 kat, ilk 10 dakikada 2,5 kat daha yüksek olduğu görülmüştür. Önerilen kaplama yönteminin tekrarlanabilirliği incelendiğinde, kaplama kalınlıklarının ortalamadan en fazla %5,3 gibi düşük bir sapma ile üretilebildiği görülmüştür. Ek olarak üretilen kaplamaların desorpsiyon kinetiklerinin de neredeyse aynı olduğu gözlenmiştir. Ayrıca kurulan sistemin parametreleri dar aralıklarda rahatlıkla kontrol edilebilmiştir. Artan sentez süresinde sınırlayıcı reaktan konsantrasyonunun azalması nedeniyle kaplama oluşum hızının düştüğü görüldüğünden, sistemde dolaşan çözelti hacmi artırılarak tek sentez adımında elde edilen kaplama miktarının artırılmasına çalışılmıştır. Çözelti hacminin etkisini araştırmak için kreostat ve reaktör giriş-çıkışı arasındaki boru hatları uzatılarak sistem hacmi arttırılmıştır. Bu bölüme kadar yapılan deneylerde kullanılan çözelti hacminin %25 ve %50 fazlasının kullanıldığı deneyler gerçekleştirilmiştir. Çözelti hacmi %25 arttırıldığında kaplama kalınlığının arttığı, %50 arttırıldığında ise %25 artışa kıyasla azaldığı görülmüştür. Bu duruma, çözelti hacmi %50 arttırıldığında, çözelti içinde ve boru yüzeylerinde oldukça fazla katı oluşması sonucunda kaplama veriminin düşmesi neden olmuştur. Önceki çalışmalarda boru hattındaki çizgisel hızın daha az olduğu durumlarda, çözelti içinde ve boru yüzeyinde katı oluşumunun azaldığı görüldüğü için, boru hattındaki hızın azaltılması hedeflenmiştir. Bu nedenle reaktör çıkışından kreostata kadar olan, kreostatın içindeki ve kreostat çıkışından tekrar reaktöre dönen hatlar birbirine eş, iki paralel hat olarak bağlanmıştır. Boru hattının paralel olarak bağlanmasıyla,çözeltide ve boru yüzeyinde katı oluşumu engellenebilmiştir. Çözelti hacminin %50 arttırıldığı (paralel hat ile) durumda, %25 artış ile elde edilen kaplamaya yakın kalınlıkta kaplama elde edildiği, kaplama oluşma hızının bir maksimuma ulaştığı ve sınırlayıcı reaktan miktarının hızı belirleyen adım olmaktan çıktığı görülmüştür. Tek bir sentez adımında elde edilen kaplama miktarını ve kaplamanın tuttuğu toplam nem miktarını arttırabilmek adına, kaplama hazırlamaya uygun berrak sentez çözelti bileşimleri araştırılmıştır. Bu amaçla farklı SiO2/Al2O3, H2O/Na2O ve H2O/SiO2 oranlarına sahip sentez bileşimleri ile geleneksel toz sentez deneyleri yapılmıştır. Elde edilen tozların kristaliniteleri, fazları ve toplam nem tutma kapasiteleri incelenmiştir. Bileşimlerin jelleşme eğilimleri ve elde edilen ürünlerin toplam nem kapasitesileri göz önüne alınarak, kaplama deneyinde kullanılabilecek yeni bir bileşim seçilmiştir. Seçilen deney koşulunda, yeni bileşimin kaplama kalınlığını yaklaşık 3 katına çıkardığı görümüştür. Yeni bileşimle, bu deneyden elde edilen kaplama kalınlığının ve kristalinitenin arttırılması adına, denenen parametrelerden elde edilen en iyi sonuçların koşulları kullanılarak bir deney daha yapılmış ve bu amaca ulaşılmıştır. Elde edilen kaplama kalınlığının, çözelti hacminin etkisinin incelendiği deneylerde ölçülmüş en yüksek kalınlığa çok yakın olduğu görülmüştür. Kaplama kalınlığının daha fazla artmaması, sınırlayıcı reaktan miktarının hız belirleyici adım olmaktan çıkması, kaplama oluşma hızını, öncül madde ve reaktanların kalınlaşan kaplama içindeki kütle iletiminin belirlemeye başlaması ile ilişkilendirilmiştir. Sonuç olarak bu çalışmada, indüksiyon ısıtma ile kaplama yöntemi kullanılarak, tek bir sentez adımı ile 400 µm kalınlığa yaklaşan, yüksek kristalinitede ve homojenlikte kaplamalar elde edilmiştir. Ayrıca tekrarlı sentezler ile bu kalınlığın çok daha fazla artırılabileceği de gösterilmiştir. Elde edilen kaplamaların ısıl ve mekanik dayanımlarının oldukça yüksek olduğu ve desorpsiyon kinetiklerinin toz ile pelet formundaki zeolitlere kıyasla çok yüksek olduğu görülmüştür.
An artificial intelligence based methodology in architectural design process: Integrated diffusion model-aided design (DMAD)

(Graduate School, 2024-10-15) Müezzinoğlu, Can ; Yazıcı, Sevil ; 523211007 ; Architectural Design Computing

The thesis focuses on the integration of Diffusion Models (DMs) that synthesize text, images, or videos based on written or visual prompts into architectural design and how architectural design process can shift. The thesis aims to develop a methodology that integrates traditional design and computational design with DMs. The design process in this thesis is separated into three distinct phases: (1) preliminary design, (2) design development, and (3) presentation of finalized design. Each phase utilizes different capabilities of DMs. The designer can use Ideative DMs in the Preliminary Design Phase to generate new ideas to contribute to concept generation. Variative DMs can be used in the Design Development Phase to generate image alternatives to the design produced by the designer in the preliminary design phase. These alternatives can be related to mass model decisions, solid-void experiments, material selection and facade decisions. In the Presentation of Finalized Design phase, the designer works with Post Productive DMs to edit the visuals which were produced with Variative DMs, for presentation. The integrated DM-aided design framework was first tested through a preliminary study, followed by a case study involving two experts who were architects undertaking their PhD degrees in architecture. In the case study, data was obtained through questionnaires and through the collection of inputs used in the design process and outputs produced. The data was analyzed under two main categories: (1) phase-based evaluation of each DM separately and (2) the overall evaluation of the design process. In phase-based evaluation, the study examines the use of various DMs across three design phases. During the preliminary design phase, DM can enhance exploration and evaluation of alternatives, providing valuable new ideas for designers. In the later phases, DMs facilitate the generation of alternatives and the creation of visuals for presentations. The effectiveness of different detection methods for image analysis is assessed using image difference method. As seen in the case study, the outputs from the various environments used throughout the design process are used as inputs in the next design environment, allowing reflection in the process. Integrating DMs into architectural design creates a dialogue between the designer and the tool, especially in the early stages. As the design process advances, the designer becomes a decision-maker. The integration of multimedia and multiscale approaches enriches the design process by expanding the search space and addressing specific design challenges efficiently. Additionally, DMs expand the design search space by generating alternative outputs throughout the process. The framework also allows for transitions between different design stages and scales. The proposed methodology has the potential to develop new strategies for architectural design.
An evaluation about decision-making mechanisms within the scope of disaster management

(Graduate School, 2022-05-16) İskender, Begüm ; Trabzon, Levent ; 801181047 ; Disaster Management

The Decision-making process in the disaster management cycle has a very significant role in making versatile and effective actions at any level of management for people including disaster managers. People may face any emergency situation or any type of disaster in an unprecedented scale and psychological extent so corresponding decisions on disaster management should be taken at the highest possible reliable level. Thus, it is very crucial to make the right decisions before/during/aftermath the disasters in order to minimize any risks which have the capacity to transform any level of hazards related to life, economy and infrastructure. This thesis's main idea is to scrutinize appropriate decision-making methods which can be useful in compatibility between two systems of thinking, called "System 1" and "System 2", otherwise they are computing to each other to induce unconditioned risk management. The thesis is based on a general literature review in disaster management and a new hypothetical decision-making model for every phase of disaster management will be proposed. The model is composed of two main different parameters of critical level and number of decisions relative impact of the time. The model is formulated and named as "Density of Decisions". It may be possible that in future studies, various parameters e.g "Decision Quality" which are related to the field can be added to the formula. Thus, the decision-making process in disaster management can attain accurate results with a measurable perspective since the level of management difficulty is linked to the density of decision model. Also, disaster managers who aim to be entitled to disaster management will be able to evaluate the effectiveness in their opinions by using the hypothetical model. Integrating two modes of thinking into our model will surely enhance disaster manager's point of view in the decision-making process while they have to make multiple decisions under uncertainties in struggling severe situations. The contribution of this research will be influential and productive in making well-directed decisions and there will be a chance to verify or interrogate their actions with the aid of different branches of science.

Sustainable Development Goal "Goal 12: Responsible Consumption and Production" ile 'a göz atma

Sayfa başına sonuç

Sıralama Seçenekleri