Selcuk University Journal of Engineering, Science and Technology
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BER OF ANNULAR BEAMS IN WEAK OCEANIC TURBULENCE
Get PDFoai:sujest.selcuk.edu.tr:article/475 Based on Rytov method, on-axis scintillation index of laser communication link in a weak oceanic medium is formulated for collimated annular beam. Employing these obtained scintillation values, average bit error rate (BER) is evaluated where the intensity has log-normal distribution. Scintillation indices of collimated annular beams are found for fixed primary source size , varying annular beam thickness, propagation distance , source size , the rate of dissipation of the mean squared temperature , non-dimensional parameter representing the relative strength of temperature and salinity fluctuation . BER versus the source size and the average signal to noise SNR found for the collimated annular beams are exhibited for various rate of dissipation of turbulent kinetic energy per unit mass of fluid and source sizes . At the stated link lengths, as secondary source size of annular beam equals to zero, that is, for Gaussian beam, BER will offer more advantages
SOLAR ENERGY SUPPORTED HYDROGEN PRODUCTION: A THEORETICAL CASE STUDY
Get PDFTwo different units that were connected to each other were modelled and solved numerically in this study. The electrical energy obtained from solar energy via photovoltaic panels were used in order to charge a battery first and then hydrogen was acquired by using aforementioned energy in the electrolysis of water. In the second stage, electricity is generated in a fuel cell by using the generated hydrogen. In this study a more effective way of solar energy utilization was aimed for the periods without sun light. A theoretical analysis was done via computer software by solving the constituted mathematical model. Data containing monthly average insolation values of Konya City according to years were used in this model. Electrolyzer temperature and pressure values and efficiencies of the photovoltaic panels were used as the input parameters. General system efficiency and effectiveness, generated electricity and hydrogen amounts were obtained as the output parameters. Among all, temperature was found to be the most effective parameter according to the obtained results considering the generated hydrogen amount, system effectiveness and efficiency. A wide range of electrical power between 400 W and 1800 W can be harnessed from the PV part of the system. Hydrogen production in the other hand can be attained in the range of 120-130 g/month. Power curve of the fuel cell at the start up of the system yields a 0.001 seconds reaction time. The proposed system can be utilized in rural parts of Konya and climatically similar regions in the world
EXAMINING PERFORMANCE OF STABILIZATION PONDS OF AHVAZ'S SLAUGHTERHOUSE
Get PDFA waste stabilization pond (WSP) is a hole in which household wastewater and other types of sewage are stored for long periods of time so that organic materials existing in them are deposited, decomposed and stabilized through exposure to light and heat and growth of algae and microorganisms. In WSPs, deposition and stabilization processes take place simultaneously. Such features make WSPs suitable for treating industrial sewage such as wastewaters produced by slaughterhouses, dairy plants and canned food factories. The present study sampled wastewaters collected and treated by the treatment plant of a slaughterhouse in Ahvaz and compared the relevant measured parameters with the standards set by the Environmental Protection Organization of Iran in order to determine the efficiency of WSPs in treating wastewaters and making them usable for irrigation purposes. The results indicate that Turbidity, BOD5, PH, COD, TDS, and TSS values for the treated wastewaters stood at 1000 NTU, 912 mg/lit, 8.78, 1520 mg/lit, 1052 mg/lit, and 2180 mg/lit respectively. A comparison of these values with the standard values set by the Environmental Protection Organization of Iran revealed a significant difference. This finding shows that the wastewater treatment plant under study had a poor productivity and performance and that wastewater treated by that facility could not be used for irrigation or pumped into surface waters. Therefore, environmental management programs and solutions have been suggested in order to help control and reduce the adverse effects of treated wastewater
EFFECT OF HEIGHT ON THE STATIC STABILITY OF HETEROGENEOUS EMBANKMENT DAMS
Get PDFThe main objective in designing an embankment dam is to achieve a structure that keeps water and in addition prevents seepage in downstream that has piping and rupture. Therefore, the present study examined the effect of height on upstream and downstream slope stability of heterogeneous embankment dams with the same characteristics but with different heights at the end of construction and Steady-State Seepage and Rapid Drawdown. To investigate the effects of height, two dams with a height of 62 meters and 133 meters and 6 meters crest width were modeled in Geostudio software. The embankment dam is composed of 14 different areas with different characteristics. To analyze the dam stability, SLOP/W and to model the movement of water in dam due to presence of water behind the dam in a Rapid Drawdown and Steady-State, seepage SEEP/W in Geostudio was used. Finally, the obtained safety factors in two dams with different height are compared with each other and the obtained safety factor was compared with USBR safety factor. This research showed that the safety factor is safer for 62 meters dam. The safety factor in shorter dam is safer than long dam
RECOVERY OF FORMIC ACID BY REACTIVE EXTRACTION USING AN ENVIRONMENTALLY-FRIENDLY SOLVENT
Get PDFToday many carboxylic acids are recovered from biological production media and industrial wastewaters. Reactive extraction is favored over other separation methods due to its high recovery efficiency, ease of operation, low energy demand and reduced cost. However, use of toxic organic diluents in the organic phases is the main disadvantage of the method. In this study, the appropriateness of an environmentally-friendly solvent, sunflower oil (SFO) to be used as organic phase diluent during the recovery of formic acid (FA) from aqueous solutions by reactive extraction was evaluated. Alamine-336 was used as the extractant and the results obtained with SFO were compared with those obtained using octanol. The separation process reached an equilibrium in 3 hours and the recovery efficiency increased with the increase in extractant percentages. The initial FA concentration positively influenced the recovery when SFO was used as the diluent. In the ranges of the parameters studied, the highest recovery values were 98.6% and 82.6% with octanol and SFO, respectively. This study shows that low molecular weight carboxylic acids, e.g. FA can be recovered from aqueous solutions by reactive extraction using environmentally-friendly solvents such as SFO
KÜPRİK OKSİT/SİLİSYUM HETEROEKLEMLİ NANODİYOTLARIN FOTOVOLTAİK ÖZELLİKLERİ
Get PDFAygıt uygulamaları için nanoyapılı materyallerin sentezlenmesinde, ucuz olması sebebiyle solüsyon-bazlı yaklaşımlar kullanılır. Bu çalışmada, Küprik oksit/Silisyum p-n heteroeklemli nanodiyotların fotovoltaik performansı incelenmiştir. Yüksek yoğunluklu ve dikey olarak düzgün sıralanmış Silisyum nanotel kümeleri, n-tipi (100)-yönelimli kristal Silisyum dilimi üzerine akımsız dağlama tekniği ile sentezlendi. Daha sonra, üç-boyutlu heteroyapılar üretmek için p-tipi Küprik oksit ince filmleri Silisyum nanoteller üzerine kimyasal depolama yöntemi ile kaplandı. Akım-gerilim (I-V) ölçümleri, üretilen heteroeklemli diyotların fotovoltaik özelliklerini incelemek için kullanıldı. AM 1.5 G aydınlatma koşulları altında en yüksek güç dönüştürme verimliliği %0,58 olarak bulundu. Ayrıca, 400-1100 nm arasında geniş bir dalgaboyu spektrumunda oldukça yüksek dış kuantum verimi saptandı
Pd/C CATALYSTS SYNTHESIZED BY MICROWAVE ASSISTED POLYOL METHOD FOR FORMIC ACID ELECTRO-OXIDATION
Get PDFSynthesis of carbon supported palladium particles based on a polyol process was investigated. The activity of Pd catalysts, synthesized by microwave assisted polyol method on carbon support, has been examined for formic acid electro-oxidation reaction. The catalysts were characterized with XRD to identify their nanostructure properties. The effect of catalyst preparation parameters on electrocatalytic performance of catalysts was examined. The electrocatalytic properties of Pd/C catalysts for the oxidation of formic acid were investigated by cyclic voltammetry (CV). The electrocatalytic activity of Pd/C synthesized at 30 s and 130 oC are higher than the other Pd/C catalysts synthesized at different temperature and reaction time. It is proposed that the longer reaction time and higher temperature increased the particle size
OBJE YÜZEY EĞİMLERİNİN YERSEL LAZER TARAYICILARIN KONUM DOĞRULUĞUNA ETKİLERİ
Get PDFLazer tarama, henüz yeni bir teknoloji olmasına rağmen günümüzde teknolojideki ilerlemelerle birlikte bu teknoloji de gelişmekte olup bununla beraber kullanım alanı da giderek artmaktadır.Lazer tarama teknolojisi ile istenilen objelerin üç boyutlu görüntüleri diğer klasik ölçme yöntemlerine göre çok daha hızlı, pratik, kolay ve yüksek doğrulukla elde edilebilmekte ve ölçümler her türlü hava koşulunda yapılabilmektedir. Ayrıca bu yöntem ile objeler, temas zorunluluğu olmadan uzaktan ölçülebilmektedir.Yapılan çalışmada Topcon Yersel Lazer Tarayıcı ile belirli bir mesafeden çeşitli açılar verdirilen test alanının taratılarak bu açıların yersel lazer tarayıcının konum doğruluğuna etkisi araştırıldı. Bunun için düşey konumda duran 2.10 m x2.80 m boyutlarına sahip bir test alanı 35 m mesafeden dik, 150, 300, 450 ve 600 lik açılar ile tarandı. Taramalardan elde edilen Y ve Z koordinatları yer değiştirilerek test alanı yatay hale getirildi. Bu durumda oluşan yarım dikdörtgen prizmanın olması gereken hacmi ile taramalardan elde edilen hacimleri hesaplandı. Hacim farklarına göre yapılan değerlendirmeler sonunda bu tarayıcının 35 m’ lik tarama mesafesinde konum doğruluğunun 2.9 mm ile 12.1 mm arasında olduğu görüldü. Ayrıca en uygun taramanın objenin 150 lik açıya sahip iken yapılan tarama olduğu gözlendi.
YATAĞAN ESKİHİSAR LİNYİT AÇIK OCAĞI BATI ŞEVLERİNDE OLUŞAN DEFORMASYONLARIN JEODEZİK YÖNTEMLE İZLENMESİ VE MATEMATİKSEL MODELLENMESİ
Get PDFAçık ocak basamaklarında şev duraysızlığı oluşması sonucu meydana gelen kaymalar yaşam kaybı yanında ekonomik kayıplara ve ocak geometrisinin bozulması gibi sonuçlara neden olabilmektedir. Bu tür olayların önüne geçilmesi için alınması gereken tedbirlerin başında emniyetli jeoteknik tasarımlar, desteklemeler, kaya düşme önleme sistemleri ve şevlerde oluşan deformasyonların değişiminin izlenmesi gelmektedir. Bu çalışma, günümüzde halen Yatağan Termik AŞ bünyesine olan ancak ölçümlerin yapıldığı yıl olan 2011’de Türkiye Kömür İşletmeleri Güney Ege Linyitleri İşletmesi’ne (TKİ-GELİ) bağlı olan Yatağan–Eskihisar linyit açık ocağında gerçekleştirilmiştir. Ocakta yapılan incelemeler ve ön değerlendirmeler neticesinde ocağın batı tarafındaki şevlerde şev duraysızlığı olasılığı bulunan alanlar tespit edilmiştir. Bu alanlarda karşılaşılan ve tehlike yaratacağından kuşkulanılan şevdeki hareketi izlemek amacıyla tespit edilen çekme çatlağındaki deformasyon değişimlerinin izlenmesine karar verilmiştir. Bu kapsamda sahada belirlenen bu sorunlu bölgelerde izleme çalışmaları yapılmasına karar verilmiştir. Ocakta dekapaj ve kömür üretimi sonrası batı şevlerinde oluşan gerilim çatlakları ve buna bağlı gelişen şev duraysızlığı olasılığı nedeniyle ölçüm istasyonları kurularak, jeodezik ölçüm yöntemleriyle 216 günlük bir süreçte belirli aralıklarla şev hareketliliği izlenmiştir. Elde edilen veriler sonucunda şevdeki deformasyon hareketliliği değerlendirilmiş ve hareketin orta hızlı bir eğilimde devam ettiği belirlenmiştir. Bu hareketliliğe bağlı bir matematiksel eşitlik geliştirilmiştir. Geliştirilen model sonuçları ile gerçek veriler arasında yüksek korelasyon mevcuttur. Bu model ile şevde gelecekte oluşabilecek deformasyon miktarları ve hızlarını tahmin etme ihtimali oluşabilecektir
COMPARISON OF ASTER AND SRTM DIGITAL ELEVATION MODELS AT ONE-ARC-SECOND RESOLUTION OVER TURKEY
Get PDFIn February 2000, the “Shuttle Radar Topography Mission (SRTM)” satellite captured elevation data by scanning the Earth landmasses between the 60o North and South latitudes. After the mission of 11 days, the collected data were processed, and a Digital Elevation Model (DEM) within one arc-second resolution for United States and three arc-second resolutions for the other parts of the globe was created and published on the NASA servers. Recently, a global SRTM DEM with one-arc-second resolution has been released. Additionally, ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is a sensor boarded on the Terra satellite in 1999. The sensor has been collecting satellite imagery since 2000. The ASTER GDEM at one-second resolution was released to the public, which is the most complete DEM of the earth ever made. In this study, SRTM and ASTER DEMs with one arc-second resolution over Turkish territory was evaluated by means of a local DEM produced from 1:25K national topographic maps. Results show that the accuracy of the SRTM DEM is better than the ASTER GDEM with respect to the local DEM