Dynamic force measurement techniques Split Hopkinson Pressure Bar testing of low acoustic impedance materials used as armor interlayer materials

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2012Includes bibliographical references (leaves: 50-52)Text in English; Abstract: Turkish and Englishx, 52 leavesGoreTM PolarchipTM heat insulating Teflon and Dow ChemicalsTM Voracor CS Polyurethane were characterized in this study by conducting compression tests at various strain rates. Quasi-static compression tests were done with a Shimadzu AG-X conventional test machine while two different modified Split Hopkinson Pressure Bar (SHPB) systems were used for dynamic compression tests. Since dynamic testing of soft materials with classical SHPB is problematic due to low signal levels and relatively higher signal to noise ratio, impact end of transmitter bar was modified with insertion of piezoelectric force transducers through the SHPB tests of Teflon, thus enabling the direct measurement of force on specimen. High strain tests of Polyurethane involved oscillations in both incident and transmitter bar signals. To overcome this, EPDM rubber pulse shaper was used through the SHPB tests of Polyurethane. Experimental results were used in numerical study as material model parameters and SHPB tests of both materials were simulated in LS-DYNA. Experimental study concluded strong strain rate dependency in both Teflon and Polyurethane, depicting an increase in maximum stress with the increase in strain rate. Numerical study showed a good correlation with experiments in terms of bar stresses and damage behavior of specimens, offering a solution to more complex problems that can be encountered in future studies

Metal concentrations in surface sediments of beyler reservoir (Turkey)

The accumulation of metals (Iron, Aluminium, Zinc, Copper, Manganese, Boron, Chromium, Nickel, Cadmium, Lead) was seasonally (November 2009 to July 2010) measured in sediment samples taken from different areas of Beyler reservoir which is an important water source for irrigation in West Black Sea region (Turkey). Metals in sediment samples were analyzed by ICP-OES. The difference between the stations except for Zn metal (p\0.05) has not been considered as important and a statistical difference between seasons for Fe, Ni metals (p\0.01) and Cu metal (p\0.05) has been observed. The magnitude of metal concentrations in sediment was determined as Aluminium[ Iron[Manganese[Zinc[Chromium[Copper[ Boron[Nickel[Lead[Cadmium. Enrichment factor (EF) for all metals has been calculated (EF\1). In the evaluation done by considering the EF values, it is seen that the metal concentrations found in the Beyler Dam Lake sediment stem from the natural composition of the sediment.The authors are grateful for the financial support of the Scientific and Technological Council of Turkey, TUBITAK (Project No: 109Y013)

Bazı Organik Materyallerin Fındıkta Verim ve Kalite Üzerine Etkileri

Bu araştırma organik fındık üretim olanaklarının araştırılması amacıyla 2002–2006 yılları arasında Giresun’da yürütülmüştür. Tombul çeşidinde kontrol ve konvansiyonel üretimin yanında çiftlik gübresi ve zuruf kompostu uygulamaları denenmiştir. Ayrıca yazıcı böcekler ve fındık kurduna karşı organik uygulamalar yapılmıştır. Çalışma sonucunda; gübre dozları ile verim, meyve ağırlığı, iç ağırlığı, kabuk kalınlığı, randıman, beyazlama oranı, yağ oranı ve protein oranı arasındaki ilişkiler istatistikî olarak önemli bulunmamıştır. Bu durum gübre dozlarının meyve kalitesine etkisinde uygun doz seçimini zorlaştırmıştır. Ancak verim ve meyve kalite değerleri bakımından konvansiyonel uygulamayla birbirine yakınlık gösteren çiftlik gübresinin 25kg/bitki ve zuruf kompostu uygulamasının 50kg/bitki dozları önerilebilir bulunmuştur. Diğer yandan fındık ana zararlılarından olan yazıcı böceklerle mücadelede biyoteknik mücadelenin kültürel uygulamalarla beraber yürütülmesinin zarar yoğunluğunu düşürdüğü tespit edilmiştir. Ancak bu uygulamaların tek başına yeterli olmadığı ayrıca, Temmuz-Ağustos aylarındaki aşırı yağışlarından dolayı dalkıran zarar yoğunluğunun organik yetiştiricilikte arttığı belirlenmiştir

Plazma okside edilebilirlik testi koroner kalp cerrahisi geçiren hastalarda antioksidan durumu yansıtmayabilir

[Abtract Not Available

Estimation of delay and vehicle stops at signalized intersections using artificial neural network

Delay and number of vehicle stops are important indicators that define the level of service of a signalized intersection. Therefore, they are usually considered for optimizing the traffic signal timing. In this study, ANNs are employed to model delay and the number of stops estimation at signalized intersections. Intersection approach volumes, cycle length and left turn lane existence were utilized as input variables since they could easily be obtained from field surveys. On the other hand, the average delay and the number of stops per vehicle were used as the output variables for the ANNs models. Four-leg intersections were examined in this study.  Approach volumes including turning volumes are randomly generated for each lane of these intersections, then the traffic simulation program was run 196 times with each generated data. Finally, average delay and the number of stops per vehicle were obtained from the simulations as outputs. In this study, various network architectures were analyzed to get the best architecture that provides the best performance. The results show that the ANNs model has potential to estimate delays and number of vehicle stops