A graph theoretical perspective for the unsupervised clustering of free text corpora

This thesis introduces a robust end to end topic discovery framework that extracts a set of coherent topics stemming intrinsically from document similarities. Some topic clustering methods can support embedded vectors instead of traditional Bag-of-Words (BoW) representation. Some can be free from the number of topics hyperparameter and some others can extract a multi-scale relation between topics. However, no topic clustering method supports all these properties together. This thesis focuses on this gap in the literature by designing a framework that supports any type of document-level features especially the embedded vectors. This framework does not require any uninformed decision making about the underlying data such as the number of topics, instead, the framework extracts topics in multiple resolutions. To achieve this goal, we combine existing methods from natural language processing (NLP) for feature generation and graph theory, first for graph construction based on semantic document similarities, then for graph partitioning to extract corresponding topics in multiple resolutions. Finally, we use specific methods from statistical machine learning to obtain highly generalisable supervised models to deploy topic classifiers for the deployment of topic extraction in real-time. Our applications on both a noisy and specialised corpus of medical records (i.e., descriptions for patient incidents within the NHS) and public news articles in daily language show that our framework extracts coherent topics that have better quantitative benchmark scores than other methods in most cases. The resulting multi-scale topics in both applications enable us to capture specific details more easily and choose the relevant resolutions for the specific objective. This study contributes to topic clustering literature by introducing a novel graph theoretical perspective that provides a combination of new properties. These properties are multiple resolutions, independence from uninformed decisions about the corpus, and usage of recent NLP features, such as vector embeddings.Open Acces

New possibilities of living together in post-humanist society: Interior and furniture design for pets

With their various physical differences, pets have to live with their owners in interiors, which is designed according to human scale. On the other hand, human-specific anthropometric measurements, which are the basic parameters in space design, are not sufficient to provide ergonomics in indoor spaces, which are also living spaces for pets. The hypothesis of this study, in which current examples of interior and furniture designs suitable for the physical needs of pets, whose numbers are increasing day by day, are discussed with an inclusive approach in interior architecture; It has been determined as 'when the interiors where pets live are redesigned according to the characteristics of the animals, ergonomics is provided for 'all living things' in the common living areas. The subject of common living space in the literature; Although it has been investigated in interdisciplinary fields such as cognitive psychology, zoology, and architecture on topics such as biodiversity, sustainability, animal welfare, and animal behavior, the subject of 'space organization of shared living spaces shared with domestic animals' as a new approach in the field of interior architecture has not been sufficiently discussed. For this reason, the research is a pioneering and descriptive study in terms of drawing attention to current practices in terms of conceptual infrastructure, architectural design, space organization, application examples and experimental models, making a systematic review of existing studies on the subject, and identifying new trends in the field of interior architecture. The aim of the research is to expand the interior design, which is a multidimensional subject, to include spaces designed for living with pets, in particular the arrangement of common living spaces. Since subjects such as interior design, interior architecture, and design have a wide field of research, the scope of the study is limited to the specific space and furniture designs designed for pets in terms of ease of research. In the descriptive study, the survey model, one of the quantitative research methods, was preferred as a research method to review the existing status of the researches in the field of design within the existing sample applications. As a result of the study, it has been understood that the 'interior and furniture design for pets' approach is a design approach that is open to development, is an inclusive application in the interior and has a high potential to be preferred

Management and recycling of constructional solid waste in Turkey

AbstractControl and management of solid waste materials created during/after building/demolition and renewal of a structure is one of the most important problems of modern societies today. Solid waste materials which are differentiated depending on properties of structure and construction technique generally consist of materials such as concrete, brick, stone, briquette, wood, metal, glass, gypsum, plastic, ceramic. The matter of reuse was created as a result of limited capacity of reserves of sources and increased consumption depending on increase of population. Today it is possible reuse of various solid wastes. Consequently, evaluation of construction wastes which are used as primary aggregate source in construction industry, became very important in our world where natural sources were finished. Target of that study is examining utilization ratio of materials preferred during building process of structures by recycling at the end of utilization life for “Construction/ demolition wastes management and reuse”; control of environmental pollution, ecologic balance and economical development and discussion by providing examples from Turkey

The use of short-term analysis of heart rate variability to assess autonomic function in obese children and its relationship with metabolic syndrome

Background: The cardiovascular autonomic nervous system in obese children is one of the main initiators of coronary heart disease and hypertension and may have a close relationship with insulin resistance. Heart rate variability is one non-invasive method to assess the cardiovascular autonomic system. In this method, low frequency parameters reflect sympathovagal activity, high frequency parameters reflect vagal activity and the ratio of these parameters reflects sympathovagal balance. Methods: In this study, a short-term analysis of heart rate variability was conducted in 66 obese children and 40 healthy controls. Results: While high frequency parameter values are lower in the obese group compared to the controls (16.02 &#177; 12.9 nu vs. 21.45 &#177; 13.6 nu, p = 0.046), the low frequency/high frequency ratio is found significantly higher (3.79 &#177; 2.34 vs. 2.25 &#177; 0.93, p < 0.001). A significant difference was not detected for the low frequency values (p = 0.787). Insulin resistance was found in 33 (50%) patients, dyslipidemia was found in 39 (59%) and hypertension was found in 18 (27%). Metabolic syndrome was detected in 39% patients in the obese group. Conclusions: We found that vagal activity was decreased in the obese group and the autonomic nervous system balance was impaired in favor of sympathetic activity in the short-term heart rate analysis. (Cardiol J 2012; 19, 5: 501-506

Ysz ve csz esaslı termal bariyer kaplamaların üretimi, karakterizasyonu ve termal çevrim performanslarının karşılaştırılması

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Gaz türbin motorlarında sıcak kesitlerde görev yapan türbin kanadı gibi parçalarda yaygın olarak kullanılan termal bariyer kaplamalar (TBK), termal yalıtım sağlayarak metal yüzey sıcaklığını azaltmakta ve bunun sonucunda da iş parçasının dayanımını ve motor verimliliğini artırmaktadır. Tipik bir TBK sistemi iki tabakadan oluşmaktadır. Süper alaşım altlık üzerinde sırasıyla oksidasyona dirençli MCrAlY (M:Ni/Co) esaslı bağ tabaka ve üzerine de termal yalıtım görevi yapan stabilize zirkonya esaslı bir seramik tabaka kaplanmaktadır. Yitriya (Y2O3) ile stabilize zirkonya (ZrO2) (YSZ), altlık ile uyumlu yüksek termal genleşme katsayısına sahip olması ve düşük termal iletkenliği nedeniyle genel olarak en çok tercih edilen yalıtım tabaka malzemesidir. TBK sistemleri arasında Serya (CeO2) ile stabilize zirkonya (CSZ) ise YSZ'ye göre daha yüksek termal genleşme katsayısına ve daha düşük termal iletkenlik katsayısına sahip olması nedeniyle YSZ'ye alternatif bir malzeme olarak düşünülmekte ve üzerinde kapsamlı araştırmalar sürdürülmektedir. Bu tez çalışmasında Taguchi ortogonal deneysel tasarım dizileri kullanarak stabilize zirkonya esaslı kaplamaların plazma sprey prosesi ile üretiminde (F4MB plazma sprey tabancası ile) plazma sprey proses parametrelerinin (Ar, H2, Sprey mesafesi, Akım) kaplamalarda birikme verimine, mikro sertliğe, yapışma dayanımına, yüzey pürüzlülüğüne ve porozite oranına etkisi araştırılmıştır. Ar ve H2 gaz akış hızları en önemli proses parametreleri olarak belirlenmiştir. Bu parametreler toz parçacıkların plazma jeti içerisinde uçuş davranışını belirleyerek parçacık sıcaklığı ve hızını etkilemektedir. Dolayısıyla da kaplamaların makroyapısını ve özelliklerini belirlemektedir.Yüksek sıcaklıklarda termal çevrim sonrasında kaplamalarda karşılaşılan hasar türleri genel olarak termal yükleme koşullarına ve TBK sistem karakteristiklerine (bağ ve üst tabaka kalınlıkları ile seramik tabakada porozite oranına) bağlı olarak değişmektedir. 1300 °C'nin üzerinde yüzey sıcaklıklarında seramik tabakada çatlak oluşumu ve kenar dökülmelerin başladığı gözlenmiştir. TBK sistemlerde bağ tabaka kalınlığı ve porozite oranı termal çevrim ömrünü ve kaplama dayanımında en önemli efektif faktörlerdir. Sonuç olarak CSZ kaplamaların termal çevrim performansının 1350 °C'de YSZ'ye göre daha yüksek olduğu belirlenmiştir.Thermal barrier coatings (TBCs) are frequently used on the blades and vanes of gas turbines to provide thermal insulation, thus lowering the metal temperature and consequently improving component durability and increasing engine efficiency. A typical two-layer TBC system consists of an oxidation-resistant MCrAlY (M=Ni and/or Co) bond coat on the superalloy and a thermally insulating stabilized zirconia top coat applied to its surface. Yttria (%wt. 6-8 Y2O3) stabilized zirconia (YSZ) has been usually chosen for the top insulating coat material because of its high thermal expansion coefficient, which closely matches that of the substrate, and low thermal conductivity. Among the TBC systems, ceria (CeO2) stabilized zirconia (CSZ)-based TBCs have been intensively investigated for the YSZ replacement because CSZ has a much lower thermal conductivity and a higher thermal expansion coefficient than those of YSZ. In this thesis, the plasma spray process parameters (F4MB plasma spray gun: Ar, H2, Spray Distance, Current) both of stabilized zirconia coatings with respect to deposition efficiency, porosity, surface roughness and microhardness were investigated using an orthogonal array in design of experiments (Taguchi). Ar and H2 flow rates are the most important parameters in the process. These parameters influence the particle trajectory within the plasma jet and consequently the key parameters of particle temperature and velocity upon impact. Hence these factors decisively influence and determine the coating macrostructure and properties.The kind of failure after thermal cycling in such coatings depends on the thermal loading conditions and on the TBC system characteristics (thickness of bond coat and top coat, porosity of ceramic layer). With surface temperatures above 1300 °C, it is often observed that cracks develop in ceramic layer and spallation occured. Bond coat thickness and porosity of ceramic layer in TBC systems are the most effective factors for thermal cyling life time and durability. As a result, thermal cycling performance of the CSZ coatings higher than the YSZ based coatings at 1350 °C

Performance Analysis of the Differential Evolution and Particle Swarm Optimization Algorithms in Cooperative Wireless Communications

In this study, we evaluate the performance of differential evolution (DE) and particle swarm optimization (PSO) algorithms in free-space optical (FSO) and mobile radio communications systems. In particular, we obtain the optimal transmission distances for multiple-relay nodes in FSO communication systems and optimal relay locations in mobile radio communications systems for the cooperative-diversity networks, using both algorithms. We investigate the performance comparison of DE and PSO algorithms for the parallel decode-and-forward (DF) relaying. Then, we analyze the cost functions. Furthermore, we present the execution time and the stability of the DE and PSO algorithms

From Free Text to Clusters of Content in Health Records: An Unsupervised Graph Partitioning Approach

Electronic Healthcare records contain large volumes of unstructured data in different forms. Free text constitutes a large portion of such data, yet this source of richly detailed information often remains under-used in practice because of a lack of suitable methodologies to extract interpretable content in a timely manner. Here we apply network-theoretical tools to the analysis of free text in Hospital Patient Incident reports in the English National Health Service, to find clusters of reports in an unsupervised manner and at different levels of resolution based directly on the free text descriptions contained within them. To do so, we combine recently developed deep neural network text-embedding methodologies based on paragraph vectors with multi-scale Markov Stability community detection applied to a similarity graph of documents obtained from sparsified text vector similarities. We showcase the approach with the analysis of incident reports submitted in Imperial College Healthcare NHS Trust, London. The multiscale community structure reveals levels of meaning with different resolution in the topics of the dataset, as shown by relevant descriptive terms extracted from the groups of records, as well as by comparing a posteriori against hand-coded categories assigned by healthcare personnel. Our content communities exhibit good correspondence with well-defined hand-coded categories, yet our results also provide further medical detail in certain areas as well as revealing complementary descriptors of incidents beyond the external classification. We also discuss how the method can be used to monitor reports over time and across different healthcare providers, and to detect emerging trends that fall outside of pre-existing categories.Comment: 25 pages, 2 tables, 8 figures and 5 supplementary figure