Browsing by Subject "Energy Harvesting"

Now showing 1 - 4 of 4

Open Access
Code design for energy harvesting and Joint energy and information transfer Using run length limited codes
(2018-07) Özateş, Mert
Energy harvesting wireless networks and networks that bene t from wireless energy transfer have become popular in the last decade. In these networks, the users can obtain the required energy for transmission from an external source, which eliminates the need of battery replacement. Therefore, such networks have a high potential for applications in different areas including wireless sensor networks, wireless body networks and Internet of Things (IoT). While there have been many advancements for energy harvesting communications and joint energy and information transfer from information and communication theoretic perspectives in the literature, these subjects have not been studied from a practical coding and transmission point of view in depth. With the above motivation, in this thesis, we propose a serially concatenated coding scheme to communicate over binary energy harvesting communication channels with additive white Gaussian noise (AWGN), and design explicit and implementable codes for both long and short block lengths. Run length limited (RLL) codes are used to induce the required nonuniform input distributions for both cases. We employ low density parity check (LDPC) codes for long block lengths, while for short block length designs, we utilize convolutional codes for error correction. We consider different decoding approaches for the two cases, i.e., an iterative decoder is used for the former while Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm over the product trellis of the convolutional and run length limited codes is used for the latter. Also, by noticing that similar coding solutions can be employed, we extend our work to joint energy and information transfer for both scenarios. Numerical examples demonstrate that the newly optimized codes with an inner RLL code are superior to the point-to-point optimal codes for AWGN channels for long block lengths when energy harvesting or joint energy and information transfer is considered, and that, for the short block length case, concatenated convolutional and RLL codes with higher minimum distances offer excellent performance.
Open Access
EHPBS: Energy harvesting prediction based scheduling in wireless sensor networks
(IEEE, 2013) Akgun, B.; Aykın, Irmak
The clustering algorithms designed for traditional sensor networks have been adapted for energy harvesting sensor networks (EHWSN). However, in these algorithms, the intra-cluster MAC protocols to be used were either not defined at all or they were TDMA based. These TDMA based MAC protocols are not specified except for the fact that cluster heads assign time slots to their members in a random manner. In this paper, we will modify this TDMA based scheduling as follows: members will request a time slot depending on their energy prediction and the cluster heads will assign these slots to members. This method will increase the network lifetime. The proof will be given with simulations. © 2013 IEEE.
Open Access
A motion-and sound-activated, 3D-printed chalcogenide-based triboelectric nanogenerator
(Wiley-VCH Verlag, 2015) Kanik, M.; Say, M. G.; Daglar, B.; Yavuz, A. F.; Dolas, M. H.; El-Ashry, M. M.; Bayındır, Mehmet
A multilayered triboelectric nanogenerator (MULTENG) that can be actuated by acoustic waves, vibration of a moving car, and tapping motion is built using a 3D-printing technique. The MULTENG can generate an open-circuit voltage of up to 396 V and a short-circuit current of up to 1.62 mA, and can power 38 LEDs. The layers of the triboelectric generator are made of polyetherimide nanopillars and chalcogenide core-shell nanofibers.
Open Access
Spontaneous high piezoelectricity in poly ( vinylidene fluoride ) nanoribbons produced by iterative thermal size reduction technique
(American Chemical Society, 2014-08-18) Kanik, M.; Aktas, O.; Sen, H. S.; Durgun, Engin; Bayındır, Mehmet
We produced kilometer-long, endlessly parallel, spontaneously piezoelectric and thermally stable poly(vinylidene fluoride) (PVDF) micro- and nanoribbons using iterative size reduction technique based on thermal fiber drawing. Because of high stress and temperature used in thermal drawing process, we obtained spontaneously polar gamma phase PVDF micro- and nanoribbons without electrical poling process. On the basis of X-ray diffraction (XRD) analysis, we observed that PVDF micro- and nanoribbons are thermally stable and conserve the polar gamma phase even after being exposed to heat treatment above the melting point of PVDF. Phase transition mechanism is investigated and explained using ab initio calculations. We measured an average effective piezoelectric constant as -58.5 pm/V from a single PVDF nanoribbon using a piezo evaluation system along with an atomic force microscope. PVDF nanoribbons are promising structures for constructing devices such as highly efficient energy generators, large area pressure sensors, artificial muscle and skin, due to the unique geometry and extended lengths, high polar phase content, high thermal stability and high piezoelectric coefficient. We demonstrated two proof of principle devices for energy harvesting and sensing applications with a 60 V open circuit peak voltage and 10 mu A peak short-circuit current output.