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Öğe Demonstration of Resonant Adaptive Mirrors(IEEE, 2021) Kamel, Amr; Kocer, Samed; Das, Taylan; Mukhangaliyeva, Lyazzat; Saritas, Resul; Hajireza, Parsin; Yavuz, MustafaWe present a novel continuous deformable mirror (DM). The mirror can be integrated into optical systems to compensate for multiple wavefront aberrations during real-time scanning of the human retina and other targets. Specifically, it can correct all seven of the wavefront aberrations dominant in ophthalmic applications. The mirror assumes the desired shape to correct an aberration via resonant electrostatic actuation. It eliminates the need for a large number of electrodes and dependence algorithm required for spatial control of segmented DMs. It also realizes an additional benefit of dynamic amplification, thereby increasing the stroke distance. In addition, we demonstrate that the fundamental (defocus) mode of the DM can be used to change the location of the focal point for a reflected laser beam by up to 485 mu m.Öğe Long-Term Stability of Ferroelectret Energy Harvesters(MDPI, 2020) Kayaharman, Muhammed; Das, Taylan; Seviora, Gregory; Saritas, Resul; Abdel-Rahman, Eihab; Yavuz, MustafaCellular polypropylene (PP) has been recently used in energy harvesting applications. In this work, we investigate its viability and long-term stability under various operating conditions. Specifically, the effect of constant stress and stress cycling on output power and long-term stability of ferroelectret energy harvesters is analyzed. Our findings show that after 112 days constant stress significantly increases the piezoelectric charge constant d(33) and output power from 0.51 mu W for a stress-free harvester to 2.71 mu W. It also increases the harvester center frequency from 450 to 700 Hz and decreases its optimal resistance from 7 to 5.5 M Omega.Öğe Nano Groove and Prism-Structured Triboelectric Nanogenerators(Mdpi, 2023) Saritas, Resul; Al-Ghamdi, Majed; Das, Taylan Memik; Rasheed, Omar; Koçer, Samed; Gülsaran, Ahmet; Khan, Asif AbdullahEnhancing the output power of triboelectric nanogenerators (TENGs) requires the creation of micro or nano-features on polymeric triboelectric surfaces to increase the TENGs' effective contact area and, therefore, output power. We deploy a novel bench-top fabrication method called dynamic Scanning Probe Lithography (d-SPL) to fabricate massive arrays of uniform 1 cm long and 2.5 & mu;m wide nano-features comprising a 600 nm deep groove (NG) and a 600 nm high triangular prism (NTP). The method creates both features simultaneously in the polymeric surface, thereby doubling the structured surface area. Six thousand pairs of NGs and NTPs were patterned on a 6x5 cm2 PMMA substrate. It was then used as a mold to structure the surface of a 200 & mu;m thick Polydimethylsiloxane (PDMS) layer. We show that the output power of the nano-structured TENG is significantly more than that of a TENG using flat PDMS films, at 12.2 mW compared to 2.2 mW, under the same operating conditions (a base acceleration amplitude of 0.8 g).Öğe Structural Health Monitoring via Phase Space Warping and Time-Delay Embedding(Asce-Amer Soc Civil Engineers, 2023) Saritas, Resul; Das, M. Taylan; Rasheed, Omar; AlHamaydeh, Mohammad; Yavuz, Mustafa; Abdel-Rahman, EihabThe state of a structure's health can be determined by investigating its vibration characteristics. Vibration-based structural health monitoring (SHM) enables early detection and diagnosis of damage as well as extension of service life. Herein, linear and nonlinear tracking metrics are proposed to track deterioration in the condition of multistory structures and assess their instantaneous health in real-time via measurement of floor accelerations. The linear metrics, the amplitude damage index ADIn(t over bar ) and the frequency damage index FDIn(t over bar ), are based on tracking the power spectra of floor accelerations. The nonlinear metric e(t over bar ) is based on a novel implementation of the phase-space warping method and obtained from the orbits representing the floors' motions in pseudo phase-space. A scaled-down model of a four-floor moment-resisting frame building is designed and fabricated to demonstrate and to compare the capabilities of the three damage indices. Structural damage is introduced to individual columns, to mimic damage initiation, by cutting two notches on opposite sides of a column cross-section at midheight. The ADIn(t over bar ) detected large damage events, fast deterioration beyond them, and the onset of failure using any of the four floor accelerations. The FDIn(t over bar ) proved insensitive to damage compared with the other two metrics. The nonlinear metric e(t over bar ) detected gradual (fatigue-induced) deterioration in the building's health before introduction of damage, large damage events, fast deterioration beyond them, and the onset of failure, using any of the four floor accelerations. The e(t over bar ) metric varied slowly and continuously with gradual deterioration and exhibited larger discontinuous jumps with discrete damage events. This was true for all three damage experiments undertaken on the model building. The nonlinear e(t over bar ) metric was also found to be more efficient, in terms of signal utilization, in comparison with the linear ADIn(t over bar ) metric. 1415.(c) 2022 American Society of Civil Engineers.Öğe Tape'n roll inertial microfluidics(Elsevier Science Sa, 2019) Asghari, Mohammad; Serhatlioglu, Murat; Saritas, Resul; Guler, Mustafa Tahsin; Elbuken, CaglarParticle focusing and separation in microfluidic devices are critical for biological and medical applications. Inertial microfluidics is used for high throughput bio-particle focusing and separation. Most of the inertial microfluidic systems use planar structures for squeezing the particles in streams. Particle manipulation in 3D structures is often overlooked due to the complexity of the fabrication. In this study, we introduce some novel microchannel designs for inertial microfluidics by using a simple fabrication method that allows construction of both 2D and 3D structures. First, inertial migration of particles in 2D layouts including straight, spiral, and square spiral channels is investigated. Afterward, by applying a "tape'n roll" method, helical and double oriented spiral channels are configured and unexplored inertial migration behaviours are observed. Thanks to the simplicity of the fabrication and the unique characteristics of the new designs, high performance microfluidic inertial migration results can be obtained without any need for complicated microfabrication steps. The design optimization cycle can also be shortened using a computational approach we introduce in this study. (C) 2019 Elsevier B.V. All rights reserved.
