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Publication Metadata only “And in the soup kitchen food shall be cooked twice every day”: gustatory aspects of Ottoman mosque complexes(Taylor and Francis, 2016) Department of Archeology and History of Art; Ergin, Nina Macaraig; Faculty Member; Department of Archeology and History of Art; College of Social Sciences and HumanitiesN/APublication Metadata only “O/F shift” in hybrid rockets(American Institute of Aeronautics and Astronautics, 2014) Toson, Elena; Evans, Brian; Department of Mechanical Engineering; Karabeyoğlu, Mustafa Arif; Faculty Member; Department of Mechanical Engineering; College of Engineering; 114595For most hybrid rocket systems, oxidizer to fuel ratio (O/F) changes over time due to 1) natural growth of the fuel port diameter and 2) oxidizer flow rate variations, if throttling is employed. This phenomenon, which is referred to as “O/F shift”, leads to a reduction in motor performance. Note that liquid or solid rocket motors are not subject to temporal O/F variations, which is wrongfully considered as one of the most critical disadvantages of hybrid rockets. In this paper, the effect of “O/F shift” is quantified for hybrid rocket motors. Analytical formulas for the temporal O/F variation and the overall c* efficiency drop associated with the variation has been derived for single circular port motors. It has been shown that for a typical motor, c* efficiency drop due to O/F variation is well below 0.2%, a value which is too small to be measured in an actual motor test. It is also shown that for a wagon wheel type multiport configuration (with triangular ports), efficiency drop is significantly worse than the single circular port case. Even for the multiport systems, the shift does not have a controlling effect on the overall efficiency of the motor. A number of strategies have been outlined to control the adverse effects of O/F variation in a hybrid rocket. For a single circular port design with limited throttling, no mitigation is required. For systems with deep throttling requirements, aft oxidizer injection seems like a viable strategy to retain a high level of overall efficiency.Publication Metadata only “Smart poisoning” of Co/SiO2 catalysts by sulfidation for chirality-selective synthesis of (9,8) single-walled carbon nanotubes(2016) Yuan, Yang; Karahan, H. Enis; Wei, Li; Zhai, Shengli; Lau, Raymond; Chen, Yuan; N/A; Yıldırım, Cansu; Birer, Özgür; Master Student; Researcher; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); N/A; N/A; N/AThe chirality-selective synthesis of relatively large (diameter > 1 nm) single-walled carbon nanotubes (SWCNTs) is of great interest for a variety of practical applications, but only a few catalysts are available so far. Previous studies suggested that S (compounds) can enhance the chirality-selectivity of Co catalysts in SWCNT synthesis, however, the mechanism behind is not fully understood, and no tailorable methodology has yet been developed. Here, we demonstrate a facile approach to achieve the chirality-selective synthesis of SWCNTs by the sulfidation-based poisoning of silica-supported Co catalysts using a mixture of H2S and H2. The UV-vis-NIR, photoluminescence, and Raman spectroscopy results together show that the resulting SWCNTs have a narrow diameter distribution of around 1.2 nm, and (9,8) nanotubes have an abundance of ∼38% among the semiconducting species. More importantly, the carbon yield achieved by the sulfided catalyst (2.5 wt%) is similar to that of the nonsulfided one (2.7 wt%). The characterization of the catalysts by X-ray diffraction, X-ray photoelectron spectroscopy, X-ray fluorescence, and H2 temperature-programmed reduction shows that the sulfidation leads to the formation of Co9S8 nanoparticles. However, Co9S8 nanoparticles are reduced back to regenerate metallic Co nanoparticles during the synthesis of SWCNTs, which maintain a high carbon yield. In this process, Co9S8 nanoparticles seemingly intermediate the production of Co nanoparticles with narrow size distribution. Due to the fact that the poisoning step improves the quality of the end-product rather than hampering the growth process, we have coined the process developed as “smart poisoning”. This study not only reveals the mechanism behind the beneficial role of S in the selective synthesis of relatively large SWCNTs but also presents a promising method to create chirality-selective catalysts with high activity for scalable synthesis.Publication Metadata only ‘Culture’ in EU–Turkey relations(Taylor and Francis, 2016) Department of International Relations; N/A; Rumelili, Bahar; İşler, Didem Çakmaklı; Faculty Member; PhD Student; Department of International Relations; College of Administrative Sciences and Economics; Graduate School of Social Sciences and Humanities; 51356; 260783Contemporary socio-political and economic situations in the countries of SEE greatly influence their mutual relationships which are already bearing heavy loads from the past as well as distinct visions of the future. Politicians are forced to change their own priorities, sometimes even decisions, to fit the daily demands of their coalition partners or the expectations of public opinion which are often influenced by populist officials and media. The government and majority representatives condemning crimes committed in Srebrenica approved the decision of the European Parliament. Yugoslav cultural diplomacy was tuned equally toward West and East and also toward countries of the third world. All Balkan countries are open to global cultural flows but, paradoxically, their institutional systems are still closed towards the products of mass culture of neighbouring countries, particularly in the case of ethno-pop or folk music. International dimensions of national cultural policies of the Balkans primarily focus on transferring knowledge, improving the national image and increasing national influence.Publication Metadata only ‘Culture’ in EU–Turkey relations(Ashgate Publishing Ltd, 2011) Department of International Relations; Rumelili, Bahar; İşler, Didem Çakmaklı; Faculty Member; PhD Student; Department of International Relations; College of Administrative Sciences and Economics; Graduate School of Social Sciences and Humanities; 51356; 260783Contemporary socio-political and economic situations in the countries of SEE greatly influence their mutual relationships which are already bearing heavy loads from the past as well as distinct visions of the future. Politicians are forced to change their own priorities, sometimes even decisions, to fit the daily demands of their coalition partners or the expectations of public opinion which are often influenced by populist officials and media. The government and majority representatives condemning crimes committed in Srebrenica approved the decision of the European Parliament. Yugoslav cultural diplomacy was tuned equally toward West and East and also toward countries of the third world. All Balkan countries are open to global cultural flows but, paradoxically, their institutional systems are still closed towards the products of mass culture of neighbouring countries, particularly in the case of ethno-pop or folk music. International dimensions of national cultural policies of the Balkans primarily focus on transferring knowledge, improving the national image and increasing national influence.Publication Metadata only 1,3-bis(gamma-aminopropyl)tetramethyldisiloxane modified epoxy resins: curing and characterization(Elsevier, 1998) Department of Chemistry; Department of Chemistry; Yılgör, Emel; Yılgör, İskender; Researcher; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; 40527; 24181Incorporation of siloxane oligomers with reactive organofunctional terminal groups, such as amine, epoxy and carboxy, into the structure of epoxy networks, provides improvements in the fracture toughness, water absorption and surface properties of the resultant systems. 1,3-bis(gamma-aminopropyl) tetramethyldisiloxane (DSX) was used as a model curing agent and modifier in bis(4-aminocyclohexyl)methane (PACM-20) cured diglycidyl ether of bisphenol-A (DGEBA) based epoxy resins. Curing reactions followed by differential scanning calorimetry indicated faster reaction rates between DSX and DGEBA as compared with PACM-20 and DGEBA. Mechanical characterization of the modified products showed improvements in tensile and impact strengths as expected. Glass transition temperatures of these materials showed a decrease with an increase in DSX content.Publication Metadata only 1.07 - Rubberlike elasticity(Elsevier, 2012) Mark, J.E.; Department of Chemical and Biological Engineering; Erman, Burak; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 179997Molecular structure, molecular and phenomenological theories, and computer simulations of amorphous rubberlike polymeric networks of rubber elasticity are discussed. Behavior of responsive gels, multimodal, liquid-crystalline, and reinforced elastomers in the state of thermodynamic equilibrium are outlined. Characterization of structure and properties based on stress–strain experiments, optical and spectroscopic techniques, scanning tunneling microscopy, atomic force microscopy, nuclear magnetic resonance, small-angle and Brillouin scattering, and pulse wave propagation are outlined. © 2012 Elsevier B.V. All rights reserved.Publication Metadata only 10-NJ multipass-cavity femtosecond CR3+: LiCAF laser pumped by low-power single-mode diodes(Optical Society of America, 2009) Kärtner, Franz X.; Fujimoto, James G.; Demirbaş, Ümit; Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851We report on the generation of 9.9-nJ, 95-fs pulses at a repetition rate of 9.58 MHz from a multipass-cavity Cr3+:LiCAF laser pumped by single-mode diodes with a total absorbed pump power of only 540 mW.Publication Metadata only 1200 nm pumped Tm3+:Lu2O3 ceramic lasers(Optical Soc Amer, 2018) Özharar, Sarper; N/A; Department of Physics; Toker, Işınsu Baylam; Sennaroğlu, Alphan; PhD Student; Faculty Member; Department of Physics; N/A; College of Sciences; N/A; 23851We report on an experimental demonstration of a 1200-nm pumped Tm3+:Lu2O3 ceramic laser. By using a gain-switched, tunable Cr4+:forsterite laser, the excitation spectrum was measured, with optimum pumping bands centered near 1198 nm, 1204 nm, and 1211 nm. The highest slope efficiency of 21.5% was obtained at the pump wavelength of 1204 nm. Comparative energy efficiency measurements performed near 1200-nm and 800-nm pumping further showed that nearly 40% improvement was obtained in slope efficiency measured with respect to the incident pump energy for 1200-nm pumping. A transition was further observed from single-wavelength operation at 2066 nm to dual-wavelength operation near 2066 nm and 1967 nm for absorbed pump energies above 50 mu J. In this regime, two consecutive output pulses were observed in the time domain. The shortest temporal duration of the first pulse was 1.1 mu s at the incident pulse energy of 105 mu J. The duration and build-up time of the second pulse remained around 5.9 mu s and 18.5 mu s. We believe that the improved energy efficiency demonstrated for the 1.5% Tm3+:Lu2O3 ceramic with 1200-nm pumping can be used as an alternative scheme for the excitation of Tm3+:Lu2O3 ceramic lasers.Publication Metadata only 16.4: the optics of an autostereoscopic multiview display(SID, 2010) Baghsiahi, Hadi; Selviah, David R.; Willman, Eero; Fernández, Anibal; Day, Sally E.; Surman, Phil A.; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Erden, Erdem; Chellappan, Kishore Velichappattu; Ürey, Hakan; Master Student; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 8579An autostereoscopic head-tracked back projection display that uses an RGB laser illumination source and a fast light engine is described. Images are horizontally scanned columns controlled by a spatial light modulator that directs two or more images in the directions of the apposite viewers 'eyes.