Arama Sonuçları
Listeleniyor 1 - 10 / 166
Öğe N-type InP Schottky diodes with organic thin layer: Electrical and interfacial properties(Journal of Vacuum Science & Technology B, 2010-03) Güllü, Ömer; Turut, AbdulmecitThe rectifying junction characteristics of methyl red (MR) organic film on n-type InP substrate have been studied. It has been observed that MR-based structure shows an excellent rectifying behavior and that the MR film increases the effective barrier height by influencing the space charge region of the n-type InP. The barrier height and ideality factor values for this structure have been obtained as 0.75 eV and 1.93 from the forward bias current-voltage characteristics, respectively. By using capacitance-voltage characteristics at 1 MHz, the barrier height and the carrier concentration values have been calculated as 0.93 eV and 5.13×1015 cm−3, respectively. The energy distributions of the interface states and their relaxation times have been determined from the forward bias capacitance-frequency and conductance-frequency characteristics. Moreover, it was seen that both the interface-state density and the relaxation time of the interface states decreased with bias voltage from experimental results.Öğe Biodiesel production from inedible animal tallow and an experimental investigation of its use as alternative fuel in a direct injection diesel engine(Elsevier, 2009-02-15) Altun, Şehmus; Öner, CengizIn this study, a substitute fuel for diesel engines was produced from inedible animal tallow and its usability was investigated as pure biodiesel and its blends with petroleum diesel fuel in a diesel engine. Tallow methyl ester as biodiesel fuel was prepared by base-catalyzed transesterification of the fat with methanol in the presence of NaOH as catalyst. Fuel properties of methyl ester, diesel fuel and blends of them (5%, 20% and 50% by volume) were determined. Viscosity and density of fatty acid methyl ester have been found to meet ASTM D6751 and EN 14214 specifications. Viscosity and density of tallow methyl esters are found to be very close to that of diesel. The calorific value of biodiesel is found to be slightly lower than that of diesel. An experimental study was carried out in order to investigate of its usability as alternative fuel of tallow methyl ester in a direct injection diesel engine. It was observed that the addition of biodiesel to the diesel fuel decreases the effective efficiency of engine and increases the specific fuel consumption. This is due to the lower heating value of biodiesel compared to diesel fuel. However, the effective engine power was comparable by biodiesel compared with diesel fuel. Emissions of carbon monoxide (CO), oxides of nitrogen (NOx), sulphur dioxide (SO2) and smoke opacity were reduced around 15%, 38.5%, 72.7% and 56.8%, respectively, in case of tallow methyl esters (B100) compared to diesel fuel. Besides, the lowest CO, NOx emissions and the highest exhaust temperature were obtained for B20 among all other fuels. The reductions in exhaust emissions made tallow methyl esters and its blends, especially B20 a suitable alternative fuel for diesel and thus could help in controlling air pollution. Based on this study, animal tallow methyl esters and its blends with petroleum diesel fuel can be used a substitute for diesel in direct injection diesel engines without any engine modification.Öğe The effect of Plantago major Linnaeus on serum total sialic acid, lipid-bound sialic acid, some trace elements and minerals after administration of 7,12-dimethylbenz(a)anthracene in rats(SAGE, 2012-04) Oto, Gökhan; Ekin, Suat; Özdemir, Hülya; Levent, Abdulkadir; Berber, İsmetThe present study was designed to evaluate the effect of Plantago major Linnaeus (PM) extract on serum total sialic acid (TSA), lipid-bound sialic acid (LSA), some trace elements (copper (Cu), zinc (Zn) and iron) and mineral levels (magnesium, calcium and sodium) in Wistar albino rat administrated 7,12-dimethylbenz(a)anthracene (DMBA). Rats were divided into three equal groups (n = 6). Group I comprised the control group, group II was treated with DMBA (100 mg/kg, single dose) and group III was treated with DMBA (100 mg/kg single dose) and aqueous extract of PM 100 mg/kg/day for 60 days. After 60 days, statistical analyses showed that TSA and LSA levels in DMBA and DMBA + PM groups were significantly higher compared to the control group (TSA: p < 0.01, p < 0.05; LSA: p < 0.05, p < 0.05, respectively). Serum Zn levels were decreased in subjects treated with DMBA (p < 0.01) and DMBA + PM (p < 0.05) compared to the control group values. Serum Cu levels were increased in DMBA group and PM-treated group compared to the control group values. The results of this investigation showed that the levels of TSA and LSA changed significantly, which are sensitive markers for detecting the toxic effects of DMBA. On the other hand, observed decline in Zn levels in rats from DMBA + PM group might be due to decreased generation of free radicals and oxidative stress. Results from this study suggest that PM may be partially effective in preventing carcinogenesis initiated by environmental carcinogen DMBA.Öğe The comparison of engine performance and exhaust emission characteristics of sesame oil-diesel fuel mixture with diesel fuel in a direct injection diesel engine(Elsevier, 2008-01-09) Altun, Şehmus; Bulut, Hüsamettin; Öner, CengizThe use of vegetable oils as a fuel in diesel engines causes some problems due to their high viscosity compared with conventional diesel fuel. Various techniques and methods are used to solve the problems resulting from high viscosity. One of these techniques is fuel blending. In this study, a blend of 50% sesame oil and 50% diesel fuel was used as an alternative fuel in a direct injection diesel engine. Engine performance and exhaust emissions were investigated and compared with the ordinary diesel fuel in a diesel engine. The experimental results show that the engine power and torque of the mixture of sesame oil-diesel fuel are close to the values obtained from diesel fuel and the amounts of exhaust emissions are lower than those of diesel fuel. Hence, it is seen that blend of sesame oil and diesel fuel can be used as an alternative fuel successfully in a diesel engine without any modification and also it is an environmental friendly fuel in terms of emission parameters.Öğe Delphi programlama dili kullanılarak plastik enjeksiyon kalıplarında ürün maliyet hesabı ve yeni bir paket programın geliştirilmesi(e-Journal of New World Sciences Academy, 2010-07) Çelik, Yahya Hışman; Özek, Cebeli; Gürgüze, GürkanBu çalışmada, plastik enjeksiyon kalıplama tekniklerini kullanarak kalıplanan plastik ürünlerin maliyet analizini hesaplayan yeni bir program geliştirilmiştir. Geliştirilen maliyet programı için Delphi programlama dili kullanılmıştır. Program, enjeksiyon kalıplama teknikleri ile üretilen bir adet plastik ürünün maliyeti için veri bilgi girişinden seçilen değerlere göre hesaplama yapmaktadır. Elde edilen bilgilere bağlı olarak ham plastik malzeme maliyeti, kalıp maliyetine bağlı amortisman gideri, soket giderleri, işleme ve işçilik giderleri analiz edilerek plastik ürünün tahmini maliyeti hesaplanmaktadır. Programın geçerliliğini kontrol etmek için araçlardaki hava üfleme elemanı örneği seçilmiştir. Programdan elde edilen değerler gerçek değerlerle karşılaştırılarak programın geçerliliği kontrol edilmiştir. Bu verilere bağlı olarak geliştirilen paket program ile gerçek değerler arasında yaklaşık %9,7 kadar bir fark olduğu görülmüştür.Öğe Batman ili tarımsal faaliyetleri ve biyo-yakıt üretme potansiyeli(Batman Üniversitesi, 2012) Tanyeri, Burak; Öner, Cengiz; Temizer, İlkerYapılan bu çalışmada Batman ilindeki tarımsal etkinlikler ve hayvancılık ile ilgili üretimin kapasitesi araştırılmıştır. Petrol kökenli yakıtların tükenme eğilimine girmiş olmasından dolayı, bilim ve sanayi dünyası alternatif yakıtlara yönelmiş durumdadır. Literatür ışığında biyo-yakıt uygulamaları incelenerek Batman ilinde üretilebilecek biyo-yakıt türleri ve toplam potansiyeli tablolar eşliğinde verilmiştir. Sonuç olarak ilin geçim kaynağının büyük bir bölümünü oluşturan tarımdan elde edilecek tarımsal atıkların enerjiye dönüştürülerek ekonomiye katkı sağlayacağı değerlendirilmiştir.Öğe Plastik enjeksiyon kalıplarında enjeksiyon sürelerinin yapay sinir ağları ile modellenmesi(Fırat Üniversitesi, 2011) Çelik, Yahya Hışman; Özek, CebeliÖğe A general view to political and economic events causing the collapse of Mamluk State(Energy Education Science&Technology, Part B, 2012-04) Ağır, Abdullah Mesut; Solak, Kemal; Şen, Mehmet Emin; Platin, İhsann this manuscript, the collapse of Mamluk State, which reigned in Egypt and Syria between the years 1250 and 1517 has been studied. Throughout our study, there found different reasons causing this collapse; the most important ones of which are political and economic. The fact that Mamluk System which had crucial role in Mamluk administration Mechanism and the problems lived along its north border are the fundamental collapsing reasons of the state. Indeed, the fights starting with Mongols and Armenians in the north of the state continued with Anatolian Turkmens and Timurids, eventually Ottomans coming from the same direction caused it to be collapsed. Mamluks were the commercial centre between east and west. At the same time, Syria owned a very industrious trade network between Anatolia. However, the geographical discoveries that Europeans carried out and the Portuguese not only military but also commercial activities in the Indian Ocean weakened Mamluks economically. In addition to this, military struggles along the north border of the state caused incompensable deficits in Mamlûk finance. Consequently, when all these negative aspects combined with an unmodernized army, Mamlûk State closed its era in 1517, when Ottoman army defeated it in Reydaniye, which was the end of a 267 year-old-state.Öğe Uluslararası mevzuatlar ışığında Türkiye’deki yüksek eğitim sisteminde koruma eğitimi: Genel değerlendirme ve öneriler - 1(İstanbul Büyükşehir Belediyesi, 2011-12-01) Güner, Saadet; Öz, Ali Kazım; Aydın, MahmutFriends of Cultural Heritage- FOCUH (‘Kültürel Mirasın Dostları Derneği’- KUMID) in Istanbul as the Project Beneficiary and Dokuz Eylül University (DEU) in Izmir as the Project Partner carried out the Project entitled ‘EU Legislation on Cultural Heritage and Turkey’ within the framework of the ‘Civil Society Dialogue: Europe- Bridge of Knowledge Program’ between December 2006-07. In this Project, as of September 24, 2007, all EU legislations on ‘Culture’ and other international legislations published by UNESCO, COE, ICOMOS, ICOM, etc. on ‘Culture-Cultural Heritage-Conservation’ considered in ‘EU acquis communautaire’ were translated into Turkish from English (300 legislations and 2000 pages). They were published on the web site of the Project (http://www.kumid.eu/euproject/proje.html) and the Project Books within two volumes in 2007. Between 2008-09, each international legislation translated into Turkish during this Project and each article of them were analysed by the team of KUMID within the framework of various disciplines such as economy, trade, statistics, law, planning, engineering, architecture, archaeology, etc. and a draft report was prepared in 2009. This report includes three main themes: 1) Approaches and implementations of the decision makers and public instutions about the conservation of cultural heritage should be changed in parallel with contemporary and international standards as well as international engagements of the Republic of Turkey. 2) Approaches, implementations, education and training programs in each department of various disciplines related to the conservation of cultural heritage directly or indirectly in the Higher Education System of Turkey should be changed within the framework contemporary and international standards as well as international engagements of the Republic of Turkey. 3) In order to realize those themes; a) Effective public awareness on those subjects should be made. b) International and national legislations should be studied in compulsory subjects or optional courses in each department of various disciplines related to the conservation of cultural heritage directly or indirectly in the Higher Education System of Turkey. In this paper, those themes are expressed in detail. In the first part of the paper, information about ‘EU Legislation on Cultural Heritage and Turkey’ is given. In the second part, the brief history of the conservation of the cultural heritage is talked about. General analysis of the ‘International Legislation’ and ‘Education in International Legislation’ is made in the third part. In the last part of the Paper, ‘Conservation Education in the Higher Education System of Turkey’ within the Framework of the International Legislations is described in detail and some suggestions are made.Öğe Performance and exhaust emissions of a DI diesel engine fueled with waste cooking oil and inedible animal tallow methyl esters(TÜBİTAK, 2011) Altun, ŞehmusThe performance and exhaust emissions of a direct injection diesel engine were experimentally investigated using 2 biodiesel fuels with promising economic perspective, one obtained from inedible animal tallow and the other from waste cooking oils. Inedible animal tallow, which is obtained from a mixture of slaughtered cattle and sheep fats collected from a local slaughterhouse during meat preparation process, was transesterified using methyl alcohol and an alkaline catalyst to produce the inedible animal tallow methyl ester. Biodiesel from waste cooking oil was produced from waste cooking oils and methyl alcohol via a transesterification reaction, and provided by a commercial biodiesel producer. In order to investigate the performance and exhaust emissions, the experiments were conducted at different engine speeds under the full load condition of the engine. The experimental results showed, compared with diesel fuel, that the biodiesel fuels resulted in a reduction in brake torque and in an increase in brake specific fuel consumption. Although both biodiesels caused reductions in carbon monoxide (CO), the NOx emissions were higher for waste cooking oil biodiesel and lower for inedible animal tallow biodiesel as compared to diesel fuel.
