WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Access Right: Open AccessSubject: search.filters.subject.Roughness

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  • Article
    Citation - WoS: 5
    Citation - Scopus: 6
    A Simplified Method on Estimation of Forest Roughness by Use of Aerial Lidar Data
    (Wiley, 2019) Bingöl, Ferhat; Bingöl, Ferhat; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In the last decade, satellite-based measurements combined with local land cover information have produced datasets with a very detailed land cover description. CORINE Land Cover (CLC) dataset is owned and maintained by the European Environmental Agency (EEA) and published at the agency's website. Another remote sensing tool, developed in the same period, is the terrain LIDAR scanners with very high resolution and porosity information. In the current study, LIDAR scans of mainland Denmark with 0.4 m resolution were used to estimate the aerodynamic roughness of large forests, the borders of which were defined with the help of the CLC dataset. The results are compared with available in situ measurement results from the scientific literature. There was a generally good agreement between calculated and measured displacement height values but less so for aerodynamic roughness values due to the employed spatial averaging process. The results reveal a promising application that can be used for forest parameterization within modeling tools.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Electromagnetic Simulations of Mechanical Imperfections for Accelerator Cavities
    (Institute of Electrical and Electronics Engineers Inc., 2019) Karatay, Anıl; Yaman, Fatih; Karatay, Anıl; 01. Izmir Institute of Technology; 03.05. Department of Electrical and Electronics Engineering; 03. Faculty of Engineering
    Effects of surface roughness and transversal cell misalignments on the performance of elliptical accelerator cavities are studied in this article. A high-beta, 9-cell elliptical cavity, whose pi-mode resonates at 3.9 GHz, is designed to investigate imperfections. The considered frequency is chosen to observe variations of fundamental accelerating cavity parameters, wake potentials, and wake impedances more clearly by using relatively small structures. Moreover, 3-cell elliptical cavities having pi-mode at 2 and 3.9 GHz are designed to confirm the 9-cell cavity results. The undesired effects caused by the considered mechanical imperfections are simulated for an ultra-relativistic bunch in the parameter scope of a realistic scenario. In particular, Huray's snowball model, which is a scattering-based surface roughness approach developed for microstrip lines, is employed to determine the effects of the surface roughness on the accelerator cavities. Surface roughness due to the fabrication process is expressed as a surface impedance, and the required equivalence between the surface roughness and surface impedance concept is achieved. Significant computational efficiency is observed by using the surface impedance concept with Huray's snowball model in the simulations. Experimental verification of certain parameters is included for an elliptical cavity having high cell-to-cell coupling at 3.9 GHz.