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    Coarse-to-fine surface reconstruction from silhouettes and range data using mesh deformation
    (Academic Press Inc Elsevier Science, 2010) N/A; Department of Computer Engineering; Sahillioğlu, Yusuf; Yemez, Yücel; PhD Student; Faculty Member; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; 215195; 107907
    We present a coarse-to-fine surface reconstruction method based on mesh deformation to build watertight surface models of complex objects from their silhouettes and range data. The deformable mesh, which initially represents the object visual hull, is iteratively displaced towards the triangulated range surface using the line-of-sight information. Each iteration of the deformation algorithm involves smoothing and restructuring operations to regularize the surface evolution process. We define a non-shrinking and easy-to-compute smoothing operator that fairs the surface separately along its tangential and normal directions. The mesh restructuring operator, which is based on edge split, collapse and flip operations, enables the deformable mesh to adapt its shape to the object geometry without suffering from any geometrical distortions. By imposing appropriate minimum and maximum edge length constraints, the deformable mesh, hence the object surface, can be represented at increasing levels of detail. This coarse-to-fine strategy, that allows high resolution reconstructions even with deficient and irregularly sampled range data, not only provides robustness, but also significantly improves the computational efficiency of the deformation process. We demonstrate the performance of the proposed method on several real objects.
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    Dynamic control plane for sdn at scale
    (IEEE-Inst Electrical Electronics Engineers Inc, 2018) Görkemli, Burak; Tatlıcıoğlu, Sinan; Civanlar, Seyhan; Lokman, Erhan; Department of Electrical and Electronics Engineering; Tekalp, Ahmet Murat; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 26207
    As SDN migrates to wide area networks and 5G core networks, a scalable, highly reliable, low latency distributed control plane becomes a key factor that differentiates operator solutions for network control and management. In order to meet the high reliability and low latency requirements under time-varying volume of control traffic, the distributed control plane, consisting of multiple controllers and a combination of out-of-band and in-band control channels, needs to be managed dynamically. To this effect, we propose a novel programmable distributed control plane architecture with a dynamically managed in-band control network, where in-band mode switches communicate with their controllers over a virtual overlay to the data plane with dynamic topology. We dynamically manage the number of controllers, switches, and control flows assigned to each controller as well as traffic over control channels achieving both controller and control traffic load-balancing. We introduce "control flow table" (rules embedded in the flow table of a switch to manage in-band control flows) in order to implement the proposed distributed dynamic control plane. We propose methods for off-loading congested controllers and congested in-band control channels using control flow tables. A validation test-bed and experimental results over multiple topologies are presented to demonstrate the scalability and performance improvements achieved by the proposed dynamic control plane management procedures when the controller CPU and/or availability or throughput of in-band control channels becomes bottlenecks.
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    Exploring projection based mixed reality with tangibles for nonsymbolic preschool math education
    (Assoc Computing Machinery, 2019) N/A; N/A; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Salman, Elif; Beşevli, Ceylan; Göksun, Tilbe; Özcan, Oğuzhan; Ürey, Hakan; Master Student; Researcher; Faculty Member; Faculty Member; Faculty Member; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Engineering; N/A; N/A; 47278; 12532; 8579
    A child's early math development can stem from interactions with the physical world. Accordingly, current tangible interaction studies focus on preschool children's formal (symbolic) mathematics, i.e. number knowledge. However, recent developmental studies stress the importance of nonsymbolic number representation in math learning, i.e. understanding quantity relations without counting(more/less). To our knowledge, there are no tangible systems based on this math concept. We developed an initial tangible based mixed-reality(MR) setup with a small tabletop projector and depth camera. Our goal was observing children's interaction with the setup to guide our further design process towards developing nonsymbolic math trainings. In this paper we present our observations from sessions with four 3-to-5 year old children and discuss their meaning for future work. Initial clues show that our MR setup leads to exploratory and mindful interactions, which might be generalizable to other tangible MR systems for child education and could inspire interaction design studies.
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    Modeling miniaturized piezoelectric ultrasound transducers: comparison of lumped and finite element models
    (Ieee, 2020) Department of Mechanical Engineering; N/A; N/A; Department of Mechanical Engineering; Ziarati, Pouriya Torkinejad; Kullukçu, Berkay; Beker, Levent; N/A; Master Student; Faculty Member; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 308798
    In the quest to develop wirelessly-powered implantable medical devices (IMD), ultrasonic power transfer has received significant attention due to its distinct advantages (sub-mm wavelength, lower attenuation, higher allowed power intensity by the FDA) compared to other alternatives such as radio frequency-based approaches. A typical power link structure for US-based IMDs consists of a piezoelectric cube (PC) and an easy to use modeling technique would provide value insights for design of such wireless power systems. Equivalent circuit modeling (ECM) is the most common method utilized to model piezoelectric acoustic devices. In this work, a detailed analysis of two commonly used ECM models, KLM and Leach are developed specifically for a PC resonator. Then, a 3D finite element model is developed and the results of the developed ECM are compared with the finite element model results for a PC as well as other aspect ratios of the transducer. The two ECM models yielded similar results with a difference of less than 0.5%. The Leach model does not utilize frequency-dependent elements, its implementation in conventional circuit analysis software is more straightforward. Through ECM, the effect of each design parameter on transducer characteristics could be determined. However, to achieve more accurate results as the aspect ratio converges to one, the use FEM or experimental data to perform modification on ECM is necessary.