Selcuk University Journal of Engineering, Science and Technology
Not a member yet
460 research outputs found
Sort by
ÖĞÜTÜLMÜŞ CAM ELYAF TAKVİYELİ BETON (GRC) ATIKLARININ ÇİMENTO İKAME MALZEMESİ OLARAK KULLANILABİLİRLİĞİ
Get PDFTabi kaynaklardan maksimum derecede faydalanabilmek amacıyla, ekonomik değeri olan maddelerin geri dönüşümü ve tekrar kullanımı çok önemlidir. Bu çalışmada, cam elyaf takviyeli beton (GRC) atıklarının çimento ikame malzemesi olarak geri dönüşümünün sağlanabilmesi hedeflenmiştir. Ağırlıkça %0 (Referans), %5, %10 ve %15 oranında öğütülmüş GRC atıkları ile üretilen çimento harç numuneleri üzerinde; taze harç deneylerinin yanı sıra, basınç dayanımı, eğilme dayanımı, ısıtma-yağmur ve donma-çözülme deneyleri yapılmıştır. Yapılan deneysel çalışmalar sonucunda, öğütülmüş GRC atıklarının tekrar kullanılmasının çevre açısından olumlu katkı sağlayacağı ve harç içerisine %5 oranında katılmasıyla optimum sonuçlar elde edilebileceği belirlenmiştir
AN ENSEMBLE INERTIA WEIGHT CALCULATION STRATEGY IN PARTICLE SWARM OPTIMIZATION ALGORITHM
Get PDFThe ultimate success of particle swarm optimization depends on the velocity values of previous particles. Velocity is multiplied with inertia weight coefficient, and has a significant effect on search capability of the particle swarm optimization. When looking at previous studies that are carried out to calculate this coefficient, it is seen that inertia weight coefficient has been handled in several ways. In this article; a new ensemble inertia weight calculation strategy is proposed that uses other constant, random, linear decreasing, global local best, simulated annealing and chaotic inertia weight calculation methods. Other methods results are combined and used to make a final output decision in a proper way. In experimental tests, 30 common optimization benchmark test problems are used. Proposed ensemble strategy is proven by statistical tests and gives successful results in all optimization benchmark test problems
BETON KAZIKLI AÇIK DENİZ YAPISININ ANALİZİ
Get PDFBu çalışma kapsamında, alt yapısı kazıklar ile modellenen açık deniz platformunun yapısal davranışı farklı akışkan-yapı etkileşim analiz yöntemlerine göre belirlenmiştir. Yapılan analizlerde, öncelikle çift yönlü akışkan-yapı etkileşimi gerçekleştirilmiştir. Yapı çevresindeki akım, nonlineer dalga teorilerinden Stokes 5 dalga teorisi ile modellenmiştir. Çift yönlü akışkan yapı etkileşiminde Stokes 5 dalga teorisine ait hız profili Abaqus /CFD çözücüsü kullanılarak modellenmiştir. Akışkanı oluşturan deniz ortamı, Abaqus /CFD çözücüsünde modellenirken, platform Abaqus /Explicit çözücüsünde modellenmiştir. Akışkan-yapı etkileşim (FSI) modülü ile iki çözücünün etkileşimi sağlanmıştır. Sonlu elemanlar modelinde kullanılacak eleman sayısını belirleyen hassaslık analizi modal analiz üzerinden gerçekleştirilmiştir. Sonlu elemanlar analizi ile yapının modal davranışının yanında, deplasman ve gerilme değerleri elde edilmiştir. Çift yönlü etkileşim analizi ile akışkana ait çıktılar sayısal ve görsel olarak elde edilmiş ve yapı etrafındaki akış yapısı gözlemlenmiştir. Çalışmada ikincil olarak, tek yönlü akışkan yapı etkileşim analizi yapılmıştır. Bu analizde yapı, yarı analitik çok serbestlik dereceli (MDOF) sistem olarak modellenmiştir. Dalga hızları, ilk yöntemde olduğu gibi Stokes 5 dalga teorisi ile hesaplanarak, Morrison denklemi üzerinden dalga kuvvetleri sayısal olarak elde edilmiştir. Bu kuvvetler hareket denkleminde dış kuvveti oluşturmuştur. Hareket denklemi ile yapının deplasman ve doğal frekans değerleri elde edilmiştir. Her iki analizden elde edilen sonuçların uyumu gözlemlenmiştir
A K-MEANS CLUSTERING BASED SHAPE RETRIEVAL TECHNIQUE FOR 3D MESH MODELS
Get PDFDue to the large size of shape databases, importance of effective and robust method in shape retrieval has been increased. Researchers mainly focus on finding descriptors which is suitable for rigid models. Retrieval of non-rigid models is a still challenging field which needs to be studied more. For non-rigid models, descriptors that are designed should be insensitive to different poses. For non-rigid model retrieval, we propose a new method which first divides a model into clusters using geodesic distance metric and then computes the descriptor using these clusters. Mesh segmentation is performed using a skeleton-based K-means clustering method. Each cluster is represented by an area based descriptor which is invariant to scale and orientation. Finally, similar objects for the input model are retrieved. Articulated objects from human to animals are used for this study’s experiments for the validation of the proposed retrieval algorithm
HESAPLAMALI AKIŞKAN DİNAMİĞİ İLE EKSENEL BİR ÇOCUK KALP DESTEK POMPASI PERFORMANSININ İNCELENMESİ
Get PDFBu çalışmada, pompa tasarım programları kullanılarak eksenel akışlı bir çocuk kalp destek pompası tasarlandı. Bu pompanın performansı, hesaplamalı akışkan dinamiği (HAD) yazılımıyla kT-kL-w türbülans modeli kullanılarak belirlendi. Katı modeli oluşturulan pompanın gövdesi alüminyum bloktan CNC işleme tezgâhında imal edildi. Bu kalp destek pompasının çarkı, doğrultucusu ve difüzörünün 3D yazıcıyla imalatı yapıldı. Bu prototip pompanın, HAD simülasyonuyla belirlenen performans sonuçlarının deneysel doğrulaması, su ile yapıldı. Pompanın 9000-12000 dev/dak dönme sayısı aralığında, debisi 0.5-5 L/dak ve basınç farkı 35-95 mmHg arasında değişti. Kan benzeri akışkan için 2 L/dak tasarım debisi ve 80 mm-Hg’lik tasarım basıncı 11750 dev/dak dönme sayısında elde edildi. Çalışmanın sonunda, tasarım noktasında pompadaki cidar kayma gerilmeleri ve akış çizgileri incelendi
DEVELOPMENT OF 3D WEB GIS APPLICATION WITH OPEN SOURCE LIBRARY
Get PDFToday, thanks to the internet connection, the borders are disappearing and accessing information is more comfortable. Instead of desktop applications, number of web-based applications which can be seen instant changes by all users are increasing day by day. The diversity of web-based applications that are currently used in presenting spatial information to users is also spreading. Using open source libraries, developers can develop web applications for their own purposes. Three dimensional (3D) visualization on web is a commonly used approach in geographic information systems (GIS) applications. In this article, it is aimed to develop a 3D web application using open source library. Vector data layers containing attribute data on global, country and city levels are visualized on web application. The raster data layers produced in the most suitable site selection and mapping of land valuation process results are also visualized on the web application in three dimensional. It is pointed that the output products obtained from different studies can be accessed and visualized through the web browser without installing an additional program or add-ons on the users' computers
USAGE OF VARIANCE IN DETERMINATION OF SINUOSITY INTERVALS FOR ROAD MATCHING
Get PDFGeo-object matching is a process that identifies, classifies and matches the object pairs with regards to their maximum similarity in whole datasets. The matching process is used to handle updating, aligning, optimizing, integrating and/or quality measuring of road networks. There are several metrics used in matching algorithms such as Hausdorff distance, orientation, valence, sinuosity etc. Sinuosity is a ratio of actual length of a road to the straight length among start and end points of the same road. Sinuosity defines how curve a road is. In a matching process, it is necessary to determine the sinuosity thresholds or intervals firstly. Sinuosity intervals can be determined by several data classification methods such as equal interval, quantile, natural breaks and geometrical interval. Furthermore, the intervals determined by Ireland Transportation Agency can be used in parallel with this purpose. In this study, it was aimed to find out if the variance can be used in determination of sinuosity intervals as well. An experiment was conducted to compare all of the methods mentioned above. According to the results, the efficiency of the sinuosity intervals determined by the methods in road matching differs from 37.4% to 49.4%, and it seems that the intervals determined by the variance are the most efficient ones
INVESTIGATION OF SURFACE ROUGHNESS AND MICROHARDNESS IN BALL BURNISHING PROCESS OF AZ31B MAGNESIUM ALLOY
Get PDFMagnesium alloys which are lightweight and high strength materials have some limitations due to their insufficient corrosion resistance and low surface quality. To overcome these limitations, especially improving surface properties ball burnishing process was applied to magnesium alloy with different parameters like force, number of passes, feed rate and speed. For reducing number of experiments Taguchi method was used and optimum burnishing condition was determined according to S/N ratios. The results of surface roughness and hardness tests show that feed rate and force was found significant parameters for improving surface quality. When lower feed rate and higher force parameters was choosen best surface roughness value was obtained
OVERHANGS IN STRUCTURAL SYSTEMS AND EARTHQUAKE BEHAVIOUR FROM TORSIONAL IRREGULARITY POINT OF VIEW
Get PDFEarthquake behaviour of structural systems strongly depends on geometry of the building. The seismic motions can create unpredictable displacements and corresponding structural members may be forced more than that was evaluated. Torsional response of structures is very important for earthquake resistant design philosophy. In this study, overhangs in buildings and their effect on torsional displacements under seismic forces was evaluated. The model building has 5 different overhang alternatives and 3 different overhang lengths. Structural systems were modelled in a finite element packed program ETABS and investigated under response spectrum analyse cases. Mode superposition method used for determination of dynamic properties. Effect of cantilever overhangs in seismic response were evaluated
EVALUATION OF SENTINEL-2 MSI DATA FOR LAND USE / LAND COVER CLASSIFICATION USING DIFFERENT VEGETATION INDICES
Get PDFAccurate determination of Land Use/Land Cover (LULC) categories has very important role for environmental monitoring and management applications. Classification of remotely sensed data is one of the popular method to determine LULC information in different scale. Many methods have been developed and applied to classify satellite images. Freely available Sentinel-2 MSI data is new generation remotely sensed data which can be used efficiently to determine the land use and land cover categories for environmental monitoring applications. Sentinel-2 MSI data contains blue, green, red, and near-infrared-1 bands at 10 m; red edge 1 to 3, near-infrared-2, and SWIR 1 and 2 at 20 m; and three atmospheric bands (band 1, band 9, and band 10) at 60 m. In this study, the three atmospheric bands were removed. Sentinel-2A level 1C data acquired in 2018 were downloaded from Earth Explorer web page. In this study, Çatalca District of İstanbul, Turkey was selected as the study area. Çatalca is very important district for İstanbul because of its valuable agricultural fields. Different land use/cover types have been defined in the selected study area such as; water surfaces, forest areas, agricultural fields (sunflowers), open mining area, settlements, and road. Sentinel-2 data gathered in 2018, was classified by maximum likelihood classification (MLC) method to investigate the potential of the data to determine the LULC types in selected region, as the first data set. Beside the original bands, different vegetation indices such as Normalized Difference Vegetation Index (NDVI), Green–red normalized difference vegetation index (GRNDVI), and Normalized difference red-edge index (NDRE) were calculated for Sentinel-2 data. These calculated indices were added to the original bands, and classified as the other data sets. The results of these 4 data sets of Sentinel-2 image were compared based on the field collected ground control data and error matrix