You are invited to attend a lecture

Higher Order Modulation Backscatter Combined with WPT as a Solution for IoT Development

:By

Nuno Borges Carvalho

Professor Catedrático, Dep. Electronica, Telecomunicacoes e Informatica

Instituto de Telecomunicacoes, Universidade de Aveiro

Aveiro,  Portugal

Abstract

The Internet-of-Things (IoT) vision calls for thousands interconnected devices in wearables, vehicles, buildings, using a multitude of sensors to provide us with useful information.

Backscatter communication provides an enabling technology to address the needs of IoT, due to the simplicity of the tag circuit and the ability to minimize the usage of batteries or even completely eliminate them taking advantage of wireless power transmission as well as energy harvesting. This talk presents the latest advances in backscatter communication technology, covering a wide range of topics, focusing on the combination of modulation constellation diagrams with the Smith chart.

On Thursday, November 16, 2017, 15:00

Room 011, Kitot building

(The talk will be given in English)

Speaker:     Dr. Ilya Soloveychik
                   School of Engineering and Applied Sciences, Harvard University

Monday, November 20^th, 2017
15:00 - 16:00

Room 011, Kitot Bldg., Faculty of Engineering

Deterministic Random Matrices

Abstract

Random matrices have become a very active area of research in the recent years and have found enormous applications in modern mathematics, physics, engineering, biological modeling, and other fields. In this work, we focus on symmetric sign (+/-1) matrices (SSMs) that were originally utilized by Wigner to model the nuclei of heavy atoms in mid-50s. Assuming the entries of the upper triangular part to be independent +/-1 with equal probabilities, Wigner showed in his pioneering works that when the sizes of matrices grow, their empirical spectra converge to a non-random measure having a semicircular shape. Later, this fundamental result was improved and largely extended to more general families of matrices and finer spectral properties. In many physical phenomena, however, the entries of matrices exhibit significant correlations. At the same time, almost all available analytical tools heavily rely on the independence condition making the study of matrices with structure (dependencies) very challenging. The few existing works in this direction consider very specific setups and are limited by particular techniques, lacking a unified framework and tight information-theoretic bounds that would quantify the exact amount of structure that matrices may possess without affecting the limiting semicircular form of their spectra.

From a different perspective, in many applications one needs to simulate random objects. Generation of large random matrices requires very powerful sources of randomness due to the independence condition, the experiments are impossible to reproduce, and atypical or non-random looking outcomes may appear with positive probability. Reliable deterministic construction of SSMs with random-looking spectra and low algorithmic and computational complexity is of particular interest due to the natural correspondence of SSMs and undirected graphs, since the latter are extensively used in combinatorial and CS applications e.g. for the purposes of derandomization. Unfortunately, most of the existing constructions of pseudo-random graphs focus on the extreme eigenvalues and do not provide guarantees on the whole spectrum. In this work, using binary Golomb sequences, we propose a simple completely deterministic construction of circulant SSMs with spectra converging to the semicircular law with the same rate as in the original Wigner ensemble. We show that this construction has close to lowest possible algorithmic complexity and is very explicit. Essentially, the algorithm requires at most 2log(n) bits implying that the real amount of randomness conveyed by the semicircular property is quite small.

You are invited to attend a lecture

Tunable Integrated Photonic Crystal Using HOT

:By

Noam Katz

M.Sc student under the joint supervision of

Prof. Jacob Scheuer and Dr. Yael Roichman

Abstract

In this work, our goal was to demonstrate the capability of realizing dynamic, optically controlled, photonic band gap devices, and to characterize their optical properties. We did so using a holographic optical tweezers (HOT) setup. Using the HOT's dynamic, real time abilities to control the 3D position of colloidal particles, we managed to assemble dielectric particles into periodic structures between prepositioned optical fibers. Using the suggested approach, we gained the ability to post-tune the optical characteristics of the structure and thus, control the optical device's properties. In order to characterize the spectral properties of the created structures, we measured the transmission through the colloidal assembly as a function of the transmitted incident beam’s wavelength. We managed to couple to the photonic crystal device by providing a fiber coupled device with simple interfacing with external systems. Our results show that the transmission spectrum is affected by the structural details of the colloidal crystal. Furthermore, we calculated numerically the expected transmission spectrum and the colloidal material’s photonic band diagram. We found good agreement between the simulation calculation and the experimental results. 

On Thursday, November 9, 2017, 10:00

Classroom 206, Wolfson building