Yazar "Levent, Akin" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    BETA BEZIER CURVES
    (Ministry Communications & High Technologies Republic Azerbaijan, 2019) Levent, Akin; Sahin, Bayram
    In this paper, we investigate geometric properties of such curves. We construct a new curve by using curves based on new basis with beta functions satisfying various continuity condition and check shape properties. As an interesting property of such curves, we show that the curves based on new basis with beta functions do not have loops which is a useful property for CAGD systems. Since Pythagoren hodograph curves are also important in various CAD applications, we find certain conditions for Pythagorean Hodograph for the curves based on new basis with beta functions.
  • Küçük Resim Yok
    Öğe
    CUBIC BEZIER-LIKE TRANSITION CURVES WITH NEW BASIS FUNCTIONS
    (Inst Mathematics & Mechanics, Natl Acad Sciences Azerbaijan, 2018) Levent, Akin; Sahin, Bayram
    A cubic trigonometric Bezier-like curve similar to the cubic Bezier curve, with a shape parameter, is presented in this work. With the suitable shape parameter, the cubic trigonometric Bezier-like curves can be made close to the cubic Bezier curves. Then we investigate the condition of smooth connection between non-adjacent cubic trigonometric Bezier-like curves.
  • Küçük Resim Yok
    Öğe
    Spiral transitions
    (Zhejiang Univ, Editorial Committee Applied Mathematics, 2018) Levent, Akin; Sahin, Bayram; Habib, Zulfiqar
    Spiral curves are free from singularities and curvature extrema. These are used in path smoothing applications to overcome the abrupt change in curvature and super-elevation of moving object that occurs between tangent and circular curve. Line to circle spiral transition is made of straight line segment and curvature continuous spiral curve. It is extendible to other important types of transitions like line to line and circle to circle. Although the problem of line to circle transition has been addressed by many researchers, there is no comprehensive literature review available. This paper presents state-of-the-art of line to circle spiral transition, applications in different fields, limitations of existing approaches, and recommendations to meet the challenges of compatibility with today's CAD/CAM soft wares, satisfaction of Hermite end conditions, approximation of discrete data for image processing, 3D path smoothness for an unmanned aerial vehicle (UAV), and arc-length parametrization. Whole discussion is concluded with future research directions in various areas of applications.
  • Küçük Resim Yok
    Öğe
    Virtual non-enhanced dual-energy computed tomography reconstruction: a candidate to replace true non-enhanced computed tomography scans in the setting of suspected liver alveolar echinococcosis
    (Turkish Soc Radiology, 2023) Kantarci, Mecit; Aydin, Sonay; Kahraman, Aysegul; Ogul, Hayri; Irgul, Baris; Levent, Akin
    PURPOSE When a suspected hepatic alveolar echinococcosis (AE) lesion is detected on a contrast enhanced computed tomography (CT) scan, an additional triphasic or non-enhanced CT scan is required to determine the presence of calcification and enhancement. As a result, imaging costs and exposure to ionizing radiation will increase. We can create a non- enhanced series from routine contrast-enhanced images using dual-energy CT (DECT) and virtual non- enhanced (VNE) images. This study's objective is to assess virtual non-enhanced DECT reconstruction as a potential diagnostic tool for hepatic AE. METHODS Triphasic CT scans and a routine dual energy venous phase were acquired using a third-generation DECT system. A commercially available software package was used to generate VNE images. Individual evaluations were conducted by two radiologists. RESULTS The study population consisted of 100 patients (30 AE, 70 other solid liver masses). All AE cases were diagnosed [no false positives/negatives, 95% confidence interval (CI) sensitivity: 91.3%-100%; 95% CI specificity: 95.3%-100%]. Interrater agreement was k: 0.79. In total, 33 (33.00%) of the patients had AE, which was detected using both true non-enhanced (TNE) and VNE images. The mean doselength product of a standard triphasic CT was significantly higher than biphasic dual-energy VNE images. CONCLUSION In terms of diagnostic confidence, VNE images are comparable with actual non-enhanced imaging when evaluating hepatic AE. Further, VNE images could replace TNE images with a substantial radiation dose reduction. Advances in knowledge: hepatic cystic echinococcosis and AE are serious and severe diseases with high fatality rates and a poor prognosis if managed incorrectly, especially AE. Moreover, VNE images produce equal diagnostic confidence to TNE images for assessing liver AE, with a significant reduction in radiation dose.