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Now showing 1 - 4 of 4
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    Lamellar grating interferometer based compact ft spectrometers
    (IEEE, 2009) N/A; N/A; (TBD); Ferhanoğlu, Onur; Seren, Hüseyin Rahmi; Ürey, Hakan; PhD Student; Master Student; Faculty Member; (TBD); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 205198; N/A; 8579
    Lamellar grating interferometers (LGI) offer compact spectrometer architecture with high spectral resolution and large clear aperture. This study investigates the diffraction based inherent limitations of LGI spectrometers in contrary to conventional Michelson type spectrometer architecture. Simulations and experiments were conducted to demonstrate and explain periodic nature of the interferogram envelope due to Talbot image formation. Simulations reveal that grating period should be chosen large enough to avoid Talbot phase reversal at the expense of mixing diffraction orders. Overall optimization effort on the LGI system reveals that it is possible to build compact spectrometers to be used directly in the field without any performance degradation in contrary to bulky FTIR systems.
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    Reconfigurable intelligent surface enabled over-the-air uplink NOMA
    (IEEE, 2023) Çelik, Abdülkadir; Arzykulov, Sultangali; Eltawil, Ahmed M.; Department of Electrical and Electronics Engineering; (TBD); N/A; N/A; Başar, Ertuğrul; Kılınç, Fatih; Doğukan, Ali Tuğberk; Arslan, Emre; Faculty Member; Researcher; PhD Student; PhD Student; Department of Electrical and Electronics Engineering; (TBD); College of Engineering; N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 149116; N/A; N/A; N/A
    Innovative reconfigurable intelligent surface (RIS) technologies are rising and recognized as promising candidates to enhance 6G and beyond wireless communication systems. RISs acquire the ability to manipulate electromagnetic signals, thus, offering a degree of control over the wireless channel and the potential for many more benefits. Furthermore, active RIS designs have recently been introduced to combat the critical double fading problem and other impairments passive RIS designs may possess. In this paper, the potential and flexibility of active RIS technology are exploited for uplink systems to achieve virtual non-orthogonal multiple access (NOMA) through power disparity over-the-air rather than controlling transmit powers at the user side. Specifically, users with identical transmit power, path loss, and distance can communicate with a base station sharing time and frequency resources in a NOMA fashion with the aid of the proposed hybrid RIS system. Here, the RIS is partitioned into active and passive parts and the distinctive partitions serve different users aligning their phases accordingly while introducing a power difference to the users’ signals to enable NOMA. First, the end-to-end system model is presented considering two users. Furthermore, outage probability calculations and theoretical error probability analysis are discussed and reinforced with computer simulation results.
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    Towards inferring time dimensionality in protein-protein interaction networks by integrating structures: the p53 example
    (Royal Society of Chemistry (RSC), 2009) Nussinov, Ruth; Department of Chemical and Biological Engineering; Department of Computer Engineering; (TBD); N/A; Keskin, Özlem; Gürsoy, Attila; Tunçbağ, Nurcan; Makinacı, Gözde Kar; Faculty Member; Faculty Member; Faculty Member; PhD Student; Department of Chemical and Biological Engineering; Department of Computer Engineering; (TBD); The Center for Computational Biology and Bioinformatics (CCBB); College of Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; 26605; 8745; 245513; N/A
    Inspection of protein-protein interaction maps illustrates that a hub protein can interact with a very large number of proteins, reaching tens and even hundreds. Since a single protein cannot interact with such a large number of partners at the same time, this presents a challenge: can we figure out which interactions can occur simultaneously and which are mutually excluded? Addressing this question adds a fourth dimension into interaction maps: that of time. Including the time dimension in structural networks is an immense asset; time dimensionality transforms network node-and-edge maps into cellular processes, assisting in the comprehension of cellular pathways and their regulation. While the time dimensionality can be further enhanced by linking protein complexes to time series of mRNA expression data, current robust, network experimental data are lacking. Here we outline how, using structural data, efficient structural comparison algorithms and appropriate datasets and filters can assist in getting an insight into time dimensionality in interaction networks; in predicting which interactions can and cannot co-exist; and in obtaining concrete predictions consistent with experiment. As an example, we present p53-linked processes.
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    Ultrasound-assisted hexamethylenetetramine decomposition for the synthesis of alpha nickel hydroxide intercalated with different anions
    (Springer, 2015) N/A; N/A; N/A; (TBD); N/A; Ertaş, Fatma Sinem; Öztuna, Feriha Eylül Saraç; Ünal, Uğur; Birer, Özgür; Master Student; Researcher; Faculty Member; Researcher; (TBD); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 42079; N/A
    Alpha nickel hydroxide was prepared by the sonochemical degradation of hexamethylenetetramine at elevated temperatures using chloride, acetate, nitrate, and sulfate nickel salts. This method yielded dense layered structures with two different interlayer spacing of 11 and 8 . The specific capacitance of these samples was further improved by the addition of extra anions to the reaction mixtures in the form of sodium salts. This approach yielded structures in flowerlike morphology with a single interlayer spacing of 8 . The sulfate-intercalated sample, however, formed the flowerlike morphology even without the addition of extra anions. The highest specific capacitance value of 543 F g(-1), at a scan rate of 50 mV s(-1), was obtained for sulfate-intercalated sample with extra anions. The differences due to different anions likely arise from size of their solvation shells and the distance between the anions and hydroxide layer. Anions surrounded tightly by water molecules are located farther from the hydroxide layers, interact less strongly and therefore are more labile and lead to higher specific capacitance values.