Browsing by Subject "Loss"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Open Access Bodiless art(Bilkent University, 1999) Selen, EserThis research is derived from the notion of body in recent art, which may be thought within a concept of bodilessness. The aim of the study is to evaluate the answer(s) to the question “How is this bodilessness possible, if it is?”. During the study different genres of art will be discussed, examined and explored concerning both the researcher works and some contemporary artists' works, which deal with the ideas of the body. The works will be analyzed both in terms of their plastic language and by referring to psychoanalytic concepts in order to point to a way to show how the viewer/reader may experience this bodilessness as the consequence of these works.Item Open Access Commonsense aspects of buying and selling(Taylor & Francis Inc., 1996) Akman, V.; Ersan, M.We describe an experimental approach toward implementing a commonsense "microtheory" for buying and selling. Our prototype system characterizes how intelligent agents hold items and money, how they buy and sell items, and the way money and items are transferred. The ontology of the system includes money (cash, check, credit card), agents (people, organizations), items (movable, real estate, service), barter, and the notions of transfer, loan, buying by installments, profit, and loss.Item Open Access A cryptonymy of cinema : a new psychoanalytical approach to the reading of films(Bilkent University, 2007) Karaduman, ArzuThis thesis brings a new psychoanalytical approach to cinema studies bycontributing the theory of cryptonymy, which was put forward by thepsychoanalysts Nicholas Abraham and Maria Torok. After an elucidation ofthe theory of the crypt and clarification of the relationship between cryting andcinema writ large, Alfred Hitchcock’s film Rope is presented as an illustrationof the crypt in film theory. The core of the project is composed of threeparadigms for crypting in the analysis of motion pictures: loss, a-topoi, andcipher. Respectively, Pal Sletaune’s film Naboer, Andrei Tarkovsky’s Solarisand Stalker, and lastly Ken McMullen’s Ghost Dance are analyzed with thetheory of the crypt. It is also clearly pointed out that one cannot make ananalysis of the crypt without making a crypt of an analysis.Item Open Access Low-loss regrowth-free long wavelength quantum cascade lasers(Institute of Electrical and Electronics Engineers, 2018-12-01) Gündoğdu, Sinan; Demir, Abdullah; Pisheh, Hadi Sedaghat; Aydınlı, AtillaOptical power output is the most sought-after quantity in laser engineering. This is also true for quantum cascade lasers operating especially at long wavelengths. Buried heterostructure cascade lasers with epitaxial regrowth have typically shown the lowest loss due to high current confinement as well as superior lateral thermal conductivity at the expense of complexity and cost. Among the many factors affecting optical output are the widely used passivating materials such as Si3N4 and SiO2. These materials have substantial optical absorption in the long wavelength infrared, which results in optical loss reducing the output of the laser. In this letter, we report on quantum cascade lasers with various waveguide widths and cavity lengths using both PECVD grown Si3N4 and e-beam evaporated HfO2 as passivating material on the same structure. Their slope efficiency was measured, and the cavity losses for the two lasers were calculated. We show that HfO2 passivated lasers have approximately 5.5 cm-1 lower cavity loss compared to Si3N4 passivated lasers. We observe up to 38% reduction in lasing threshold current, for lasers with HfO2 passivation. We model the losses of the cavity due to both insulator and metal contacts of the lasers using Comsol Multiphysics for various widths. We find that the loss due to absorption in the dielectric is a significant effect for Si3N4 passivated lasers and lasers in the 8-12-μm range may benefit from low loss passivation materials such as HfO2. Our results suggest that low-loss long wavelength quantum cascade lasers can be realized without epitaxial overgrowth.