Selçuk-Teknik Dergisi (E-Journal - Selçuk Üniversiti)
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VERTEX COVER BASED LINK MONITORING TECHNIQUES FOR WIRELESS SENSOR NETWORKS
Get PDFVERTEX COVER BASED LINK MONITORING TECHNIQUES FOR WIRELESS SENSOR NETWORKSAbstractWireless sensor networks (WSNs) are generally composed of numerous battery-powered tiny nodes that can sense from the environment and send this data through wireless communication. WSNs have wide range of application areas such as military surveillance, healthcare, miner safety, and outer space exploration. Inherent security weaknesses of wireless communication may prone WSNs to various attacks such as eavesdropping, jamming and spoofing. This situation attracts researchers to study countermeasures for detection and prevention of these attacks. Graph theory provides a very useful theoretical basis for solving WSN problems related to communication and security issues. One of the important graph theoretic structures is vertex cover (VC) in which a set of nodes are selected to cover the edges of the graph where each edge is incident to at least one node in VC set. Finding VC set having the minimum cardinality for a given graph is an NP-hard problem. In this paper, we describe VC algorithms aiming link monitoring where nodes in VC are configured as secure points. We investigate variants of VC problems such as weight and capacity constrained versions on different graph types to meet the energy-efficiency and load-balancing requirements of WSNs. Moreover, we present clustering and backbone formation operations as alternative applications of different VC infrastructures. For each VC sub-problem, we propose greedy heuristic based algorithms.Keywords: Wireless Sensor Networks, Link Monitoring, Graph Theory, Vertex Cover, NP-Hard Problem.KABLOSUZ SENSÖR AĞLARI İÇİN KÖŞE ÖRTME TABANLI BAĞLANTI İZLEME TEKNİKLERİÖzetKablosuz sensor ağlar (KSAlar) genellikle ortamdan algılayabilen ve bu verileri kablosuz iletişim yoluyla gönderebilen pille çalışan çok sayıda küçük düğümden oluşur. KSAlar askeri gözetim, sağlık hizmetleri, madenci güvenliği ve uzay keşfi gibi çok çeşitli uygulama alanlarına sahiptir. Kablosuz iletişimin doğasında var olan güvenlik zayıflıkları, KSAları gizli dinleme, sinyal bozma ve sahtekarlık gibi çeşitli saldırılara eğilimli hale getirebilmektedir. Bu durum, araştırmacıları bu saldırıların tespiti ve önlenmesine yönelik karşı önlemleri incelemeye yöneltmektedir. Çizge teorisi, iletişim ve güvenlik sorunları ile ilgili KSA sorunlarını çözmek için çok yararlı bir teorik temel sağlar. Önemli çizge teorik yapılardan biri köşe örtmedir (KÖ), bu yapıda her bir kenarın KÖ kümesindeki en az bir düğüme bitişik olacak şekilde çizgenin tüm kenarlarını kapsayacak bir dizi düğüm seçilmektedir. Verilen bir çizge için en az elemana sahip KÖ kümesini bulmak NP-zor bir problemdir. Bu makalede, KÖdeki düğümlerin güvenli noktalar olarak yapılandırıldığı bağlantı izlemeyi amaçlayan KÖ algoritmaları açıklanmaktadır. KSAların enerji verimliliği ve yük dengeleme gereksinimlerini karşılamak için, farklı çizge yapılarında KÖ problemlerinin ağırlık ve kapasite kısıtlı versiyonları gibi çeşitli türleri çalışılmaktadır. Ayrıca kümeleme ve omurga oluşturma işlemlerini farklı KÖ altyapılarının alternatif uygulamaları olarak sunulmaktadır. Her KÖ alt problemi için, açgözlü sezgisel tabanlı algoritmalar önerilmektedir.Anahtar Kelimeler: Kablosuz Sensör Ağları, Bağlantı İzleme, Çizge Teorisi, Kenar Örtme, NP-Zor Problem.
THE ESTIMATION OF DAMAGE STATUS AND FRAGMENT SIZE DISTRIBUTION FOR MINING AND TUNNELING APPLICATIONS
Get PDFTHE ESTIMATION OF DAMAGE STATUS AND FRAGMENT SIZE DISTRIBUTION FOR MINING AND TUNNELING APPLICATIONSAbstractRock failure widely exists in geotechnical engineering, particularly in tunneling and underground mining. Accurate estimation of fragment size distribution not only can ensure the safety and efficiency of engineering projects but is also helpful to save on transportation expenses and avoid costs caused by secondary fragmentation. This research proposes a method to estimate the size distribution of rock fragmentation based on the self-similarity. In this paper, a combined use of fractal theory, elasto-plastic theory and energy conservation theory was adopted. By considering damage energy and size distribution, the fractal damage constitutive model is proposed. In this model, fragment size, damage state and fractal dimension are three main influencing factors. To verify this model, red sandstone was selected as a case study. By fitting the stress-strain curves and quantity-frequency curves, the brittle index and fractal dimension were calculated. Through utilizing the method proposed in this research, the damage status and fragment size of jointed rock mass and collapsed roof in goaf can be estimated. Eventually, implementation of the estimator model would support the attempts towards autonomous operations and vision-based monitoring approaches.Keywords: Fractal theory; Damage constitutive model; Size distribution; Rock fragmentatio
A new approach for feature extraction from functional MR images
Get PDFThe functional MR images consist of very high dimensional data containing thousands of voxels, even for a single subject. Data reduction methods are inevitable for the classification of these three-dimensional images. In this study in the first step of the data reduction, the first level statistical analysis was applied to fMRI data and brain maps of each subject were obtained for the feature extraction. In the second step the feature selection was applied to brain maps. According to the feature selection method used in the classification studies of fMRI and which is called as the active method, the intensity values of all brain voxels are ranked from high to low and some of these features are presented to the classifier. However, the location information of the voxels is lost with this method. In this study, a new feature extraction method was presented for use in the classification of fMRI. According to this method, active voxels can be used as features by considering brain maps obtained in three dimensions as slice based. Since the functional MR images have big data sets, the selected features were once again reduced by Principal Component Analysis and the voxel intensity values were presented to the classifiers. As a result; 83.9% classification accuracy was obtained by using kNN classifier with purposed slice-based feature extraction method and it was seen that the slice-based feature extraction method increased the classification.The functional MR images consist of very high dimensional data containing thousands of voxels, even for a single subject. Data reduction methods are inevitable for the classification of these three-dimensional images. In this study in the first step of the data reduction, the first level statistical analysis was applied to fMRI data and brain maps of each subject were obtained for the feature extraction. In the second step the feature selection was applied to brain maps. According to the feature selection method used in the classification studies of fMRI and which is called as the active method, the intensity values of all brain voxels are ranked from high to low and some of these features are presented to the classifier. However, the location information of the voxels is lost with this method. In this study, a new feature extraction method was presented for use in the classification of fMRI. According to this method, active voxels can be used as features by considering brain maps obtained in three dimensions as slice based. Since the functional MR images have big data sets, the selected features were once again reduced by Principal Component Analysis and the voxel intensity values were presented to the classifiers. As a result; 83.9% classification accuracy was obtained by using kNN classifier with purposed slice-based feature extraction method and it was seen that the slice-based feature extraction method increased the classification
ARTIRILMIŞ VE SANAL GERÇEKLİK İLE PERİYODİK CETVEL ÖĞRETİMİ
Get PDFARTIRILMIŞ VE SANAL GERÇEKLİK İLE PERİYODİK CETVEL ÖĞRETİMİÖzetTeknolojideki hızlı gelişmeler hayatımızın her aşamasını etkilemekte ve değişikliğe yol açmaktadır. Özellikle bilgi iletişim teknolojileri bu değişiklikte önemli rol oynamaktadır. Eğitim alanı dahil olmak üzere neredeyse tüm disiplinler bilişim teknolojilerini değişik amaçlar için kullanmaktadırlar. Mobil cihazların üretim ve kullanımındaki artış bu cihazlara yönelik teknolojilerin ve uygulamaların geliştirilmesi sonucunu doğurmuştur. Bu tür uygulamalardan olan artırılmış ve sanal gerçeklik teknolojilerinin en önemli kullanım ortamlarından biri eğitim alanıdır. Bu tür uygulamalar, kullanıcıların gerçek dünya üzerindeki sanal modellerle etkileşim kurarak, gerçekmiş gibi deneyimler yaparak eğitim-öğretime katkı sağlamaktadırlar. Eğitim kurumlarında, dersleri teorik olarak anlatırken aynı zamanda laboratuvar ortamında uygulamalar yapmak, anlaşılırlığı ve kalıcı olmasını arttıracaktır. Maalesef her eğitim kurumunun laboratuvar açacak imkanı olamamaktadır. Artırılmış ve sanal gerçeklik teknolojileri tam da bu durumdaki eksikliği giderebilecek yapıdadır. İnsanları hem eğlendirirken hem de konuyu daha cazip hale getirerek öğrenme etkisini artırabilecek ve değişik deneyim ortamları sağlayabilecektir. Fen Bilimleri dersinin de bir laboratuvar ortamında işlenmesi anlaşılırlığı daha kolay bir hale getirecektir. Bu çalışmada, Unity 3D oyun motoru ile fen bilimleri dersi içerisinde bulunan periyodik cetvel konusu için görsel eğitsel bir sanal ve artırılmış gerçeklik (karma) oyunu tasarlanmıştır. Bu uygulama ile öğrenciler periyodik cetvel konusunu bir laboratuvar ortamındaymış gibi anlayabilmektedirler. Hem sesli, hem görsel bir ortamda, eğlenceli bir şekilde periyodik cetveldeki elementleri bir deney ortamındaymış gibi deneyerek öğrenebilmektedirler. Bu uygulama ile laboratuvar imkanı bulunmayan öğrenciler deneylerini yapabilmektedirler. Uygulama ile öğrenciler hem deney ortamındaki kimyasal olarak oluşabilecek risklerden uzak olmakta hem de etkileşimli bir ortamda daha etkileyici anlama süreçlerini yaşayabilmektedirler. Gerçekleştirilen oyun Android ve IOS işletim sistemine sahip mobil cihazlarda kullanabilmektedir. Tasarlanan oyun fen bilgisi dersinde periyodik cetvel konusunu gören öğrenciler tarafından etkin ve başarılı bir şekilde uygulanmıştır. Anahtar Kelimeler: Artırılmış Gerçeklik, Sanal Gerçeklik, Periyodik Cetvel, Eğlenceli ÖğrenimPERIODIC TABLE TEACHING WITH AUGMENTED AND VIRTUAL REALITYRapid developments in technology affect every stage of our lives and lead to change. Especially information communication technologies can be important in this change. Almost all disciplines, including the field of education, use information technologies for different purposes. The increase in the production and use of mobile devices has led to the development of technologies and applications for these devices. One of the most important use environments of such augmented and virtual reality technologies is the field of education. These kinds of applications interact with virtual models on the real world and contribute to education by making experiences as real. In educational institutions, while theoretically explaining the lessons, at the same time to make applications in laboratory environment; increase the comprehensibility and persistence. Unfortunately, every educational institution cannot open a laboratory. Augmented and virtual reality technologies are capable of precisely eliminating this lack. It will enhance the learning effect and provide a variety of experience environments by making people both entertaining and making the subject more attractive. Processing a science course in a laboratory environment will make understanding easier. In this study, a visual educational virtual and augmented reality (hybrid) game is designed for the subject of periodic table in the science course with Unity 3D game engine. With this application, students can understand the subject of periodic table as if they were in a laboratory environment. They can learn the elements in the periodic table in an experimental environment, both in an audible and visual environment. With this application, students who do not have laboratory facilities can do their experiments. With the application, students are free from the risks that may occur chemically in the experimental environment and can experience more impressive understanding processes in an interactive environment. The game can be used on mobile devices with Android and IOS operating systems. The game was designed effectively by the students who took the topic of periodic table in game science course.Keywords: Augmented Reality, Virtual Reality, Periodic Table, Fun Learnin
ELEKTROSPİN METODU İLE ÜRETİLEN ZnO NANO PARTİKÜL KATKILI PAN NANOFİBERLERİN ISIL İLETKENLİĞİNİN VE ELEKTRİKSEL İLETKENLİKLERİNİN İNCELENMESİ
Get PDFELEKTROSPİN METODU İLE ÜRETİLEN ZnO NANO PARTİKÜL KATKILI PAN NANOFİBERLERİN ISIL İLETKENLİĞİNİN VE ELEKTRİKSEL İLETKENLİKLERİNİN İNCELENMESİÖzetBu çalışmada, çinko oksit (ZnO) nano partiküllerle güçlendirilmiş olan Poliakrilonitril (PAN) nanofiberlerin ısıl iletkenlikleri ve elektriksel iletkenlikleri incelenmiştir. Öncelikle, PAN+dimetilformamid (DMF) çözeltisi hazırlanmıştır. Bu çözeltide PAN ağırlıkça % 8 oranındadır. Ağırlıkça % 1, 3 ve 5 oranlarında PAN çözeltisine ZnO nano partiküller eklenmiştir. Hazırlanmış olan bu çözelti ile elektrospin işlemi kullanılarak, ZnO nano partikül katkılı PAN nanofiberler üretilmiştir. Elektrospin cihazı, 15 kV gerilimde, iğne ucu ile toplaç arasındaki mesafe 12 cm, besleme hızı 2 mL/h koşullarında çalıştırılmıştır. Saf PAN ve ZnO katkılı PAN nanofiberlerin ısıl iletkenlikleri ve elektriksel iletkenlikleri incelenmiştir. Bu çalışmada, en fazla ısı iletim katsayısı ve elektriksel iletkenlik değeri sırasıyla, 5 Watt güç için 0,91 W/mK, 5.35x10-3 S/cm’dir. Bu değerler, % 5 ZnO nano partiküllü PAN nanofiberde oluşmuştur.Anahtar Kelimeler: Elektriksel iletkenlik, elektro-eğirme metodu, ısıl iletkenlik, nanofiber, nanopartikül, PAN.INVESTIGATION OF THERMAL CONDUCTIVITY AND ELECTRICAL CONDUCTIVITY OF PAN NANOFIBERS CONTAINING ZnO NANOPARTICLES PRODUCED BY ELECTROSPINNING METHODAbstractIn this study, thermal conductivity and electrical conductivity of polyacrylonitrile (PAN) nanofibers reinforced with zinc oxide (ZnO) nanoparticles were investigated. First, PAN+ dimethylformamide (DMF) solution was prepared. In this solution, PAN is 8 % by weight. ZnO nanoparticles were added to the PAN solution at 1, 3 and 5% by weight. With this solution, PAN nanofibers with ZnO nanoparticles were produced by electrospin process. The electrospin device was operated at a voltage of 15 kV, the distance between the needle tip and the collector was 12 cm, the feed rate was 2 mL/h. Thermal conductivity and electrical conductivity of pure PAN and ZnO doped PAN nanofibers were investigated. In this study, the maximum thermal conductivity and electrical conductivity values are 0.91 W / mK for 5 Watt power and 5.35x10-3 S/cm, respectively. These values were obtained in PAN nanofiber with 5% ZnO nanoparticle.Keywords: Electrical conductivity, electro-spinning method, thermal conductivity, nanofiber, nanoparticle, PAN
SAF YÖNELİM HAREKETLERİNİ SAĞLAYAN ÜÇ SERBESTLİK DERECELİ BİR PARALEL PLATFORMUN KİNEMATİK VE DİNAMİK ANALİZİ
Get PDFSAF YÖNELİM HAREKETLERİNİ SAĞLAYAN ÜÇ SERBESTLİK DERECELİ BİR PARALEL PLATFORMUN KİNEMATİK VE DİNAMİK ANALİZİÖzetParalel platformlarda, kullanılan eyleyici sayısı, mafsal sayısı ve bunların yerleşimi ile farklı sayılarda öteleme ve yönelim serbestlik dereceleri elde edilebilir. Bu çalışmada, görüntüleyici sistemlerin bulanıklaşma ve kontrol sistemi kararlılaştırma çevriminin başarımının sınanabilmesi ihtiyacıyla, üç serbestlik dereceli paralel eksenli bir platform ile yüksek frekans ve düşük genlikli, saf yönelim hareketlerinin sağlanılabileceği bir sistem önerilmektedir. Kinematik analizler daha önceki çalışmalarda ele alınan ve bilinen formda yapılmış olup, daha önceki çalışmalarda mekanizmanın dinamik analizi için pek tercih edilmemiş olan Newton-Euler yöntemi uygulanmıştır. Bahsedilen yöntemlerle bilgisayar benzetimleri yapılmış ve elde edilen sonuçlar tartışılmıştır.Anahtar Kelimeler: Üç serbestlik dereceli paralel platform, kinematik analiz, dinamik modelleme, Newton-Euler yöntemi.KINEMATIC AND DYNAMIC ANALYSIS OF A THREE-DOF PARALLEL PLATFORM THAT PROVIDES PURE ROTATIONAL MOTIONAbstractWith parallel platform manipulators, it is possible to obtain different rotational and orientational degrees of freedom by using several number of actuator and joints. In this study, a type of spherical parallel manipulator is proposed to perform control system stabilization loop tests of imaging systems and blurring effect tests of optical systems are done by three degrees-of-freedom (DOF) manipulator with all pure rotational degrees of freedom. Kinematic analysis is done by applying the known procedure from previous works for this parallel manipulator. However, dynamic analysis of this mechanism is done by Newton-Euler methodology, which is not popular on 3-DOF parallel platform with this type of leg configuration. Computational work has been done by following procedure and the simulation results are discussed.Keywords: 3-DOF parallel platform, kinematic analysis, dynamic modelling, Newton-Euler method
PROVIDING CONTEXT-AWARE SERVICES TO DEMENTIA PATIENTS AND CAREGIVERS
Get PDFAs a result of increased human lifespan, dementia becomes a national public health and social care priority worldwide. Although, there is no cure for dementia, the wandering behavior of dementia patients can be managed by an ambient assisted living system. In this paper, Wandering Behavior Ontology (WBO) used for dealing with wandering behavior seen in early stage dementia patients is proposed. WBO is used in iCarus, which is an intelligent ambient assisted living system, for providing context-aware services to dementia patients and their caregivers. Knowledge sharing, knowledge reuse and logical reasoning are provided by using ontologies. iCarus aims to reduce the problems and financial burden associated with a wandering episode for the patients and their caregivers. It provides longer independent living for the elderly people and a cost-effective way of remotely monitoring them. The actions that are to be taken are determined by rule-based reasoning. These actions are sequential and they are defined in the developed ontology. These actions include warning the patient and informing the caregiver and the emergency service
PREDICTION OF SEPSIS DISEASE BY ARTIFICIAL NEURAL NETWORKS
Get PDFSepsis is a fatal condition, which affects at least 26 million people in the world every year that is resulted by an infection. For every 100,000 people, sepsis is seen in 149-240 of them and it has a mortality rate of 30%. The presence of infection in the patient is determined in order to diagnose the sepsis disease. Organ dysfunctions associated with an infection is diagnosed as sepsis. With the increased usage of artificial intelligence in the field of medicine, the early prediction and treatment of many diseases are provided with these methods. Considering the learning, reasoning and decision making abilities of artificial neural networks, which are the sub field of artificial intelligence are inferred to be used in predicting early stages of sepsis disease and determining the sepsis level is assessed. In this study, it is aimed to help sepsis diagnosis by using multi-layered artificial neural network.In construction of artificial neural network model, feed forward back propagation network structure and Levenberg-Marquardt training algorithm were used. The input and output variables of the model were the parameters which doctors use to diagnose the sepsis disease and determine the level of sepsis. The proposed method aims to provide an alternative prediction model for the early detection of sepsis disease
INVESTIGATION OF THE EFFECTS OF WALNUT BIODIESEL ON A DIESEL ENGINE EXHAUST EMISSIONS
Get PDFDiesel engines are the most efficient thermal machines capable of reaching up to approximately 40% of thermal efficiency. Different studies are carried out to increase the efficiency of diesel engines and also to reduce environmental pollution. The studies aimed at improving the combustion process constitute the most important part of them. As is known, with the improvement of combustion process; Besides increasing the efficiency of the engine, environmental pollution is also reduced. For this reason, in recent years to improve combustion process in diesel engines; Both structural (conconstructive) studies and fuel-related studies are underway. Structural works include exhaust manifold designs, improving the shape of the combustion chamber, increasing the valve count and Valve section area, regulations and improvements in the spraying system, the expansion of the turbocharger application, etc. Located. In the studies related to fuels; More economical use of existing fuels and studies on different alternative fuels can be given as examples.In this study, Biodiesel was produced from walnut oil by transesterification method. The walnut biodiesel is then mixed with the Eurodiesel fuel, which will be 7% (B7) and 10% (B10) by volume. Eurodiesel fuel was accepted as comparison fuel. Diesel engines with common-rail fuel system were used in the experiments. The results of the tests were compared with the emission values of CO, CO2, HC, O2, smoke and NOx with Eurodiesel fuel values
KÜRESEL GRAFİTLİ DÖKME DEMİRLERDE AŞILAYICILARIN MİKROYAPI ve MEKANİK ÖZELLİKLERE ETKİSİ
Get PDFKÜRESEL GRAFİTLİ DÖKME DEMİRLERDE AŞILAYICILARIN MİKROYAPI ve MEKANİK ÖZELLİKLERE ETKİSİÖzetKüresel grafitli dökme demirlerin alaşımlarından biri olan EN-GJS 400-15, yüksek darbe direnci, yüksek uzama kabiliyeti olan bir demir karbon alaşımıdır. Diğer küresel grafitli dökme demir çeşitlerine göre üretilebilirliği, maliyet ve üretim yöntemi açısından bakıldığında endüstride kullanımı oldukça yaygındır. Endüstride kullanımda olan farklı kimyasal bileşimlerde aşılayıcı malzemeler bulunmaktadır. Aşılayıcı malzemelerin endüstride, miktar ve kullanım yöntemleri farklılık göstermektedir. Bu sebeple bu çalışmada Baryum (Ba), Bizmut (Bi) ve Seryum (Ce) içerikli aşıların mikro yapısal ve mekanik özelliklere olan etkileri incelenmiştir. Kullanılan aşılayıcılar arasında Baryum (Ba) esaslı aşılayıcı malzemenin Kükürt (S) elementi kimyasal analizine ve mikro yapıya olan etkisi incelenmiştir. Mikroyapı karakterizasyonu optik mikroskop, mekanik özellikler ise sertlik değerleri sonuçları olarak incelenmiştir.Anahtar Kelimeler: Küresel grafitli dökme demir, aşılayıcı, EN-GJS 400-15, Baryum (Ba), Bizmut (Bi), Seryum (Ce), Kükürt (S), mikro yapı, mekanik testEFFECT OF INOCULANTS ON MICROSTRUCTURE and MECHANICAL PROPERTIES IN SPHROIDAL GRAPHITE CAST IRONS AbstractEN-GJS 400-15, one of the alloys of spheroidal graphite cast iron, is a type of iron with its high impact resistance and high elongation properties. Compared with other types of spheroidal graphite cast iron, it has been in widespread use in industry from the point of producibility, cost and production process. Inoculants with various chemical compositions are present for industrial use. Inoculants vary in terms of amount and usage in industry. For that reason, within the scope of this study, the effects of inoculants with Barium (Ba), Bismuth (Bi) and Cerium (Ce) on microstructural and mechanic properties are investigated. Among the used inoculants, the impact of inoculants containing Barium (Ba) on the chemical analysis of the element Sulfur (S) and microstructure is analyzed. Microstructures are evaluated via optic microscope while mechanic properties are evaluated in terms of hardness.Keywords: Spheroidal graphite cast iron, Inoculant, EN-GJS 400-15, Barium (Ba), Bismuth (Bi), Cerium (Ce), Sulfur (S), Microstructure, Mechanic tes