Speaker: Carmi Shimon

M.Sc. student under the supervision of Prof. Miriam Furst-Yust

Wednesday, October 30, 2019 at 15:00

Room 011, Kitot Bldg., Faculty of Engineering

The Advantage of Beamformer Cochlear Noise Reduction Algorithm to the Hearing Impaired

Abstract

Hearing aid (HA) research still have the challenge of improving the ability of the   hearing impaired (HI) to understand speech in a noisy environment. Modern HAs use multiple-channel noise reduction algorithms to reduce the background noise. A decade ago we have developed a Cochlear Noise Reduction Algorithm (CNRA) that mimics the way the cochlea process acoustic signals. We have shown experimentally that the algorithm significantly helps HI people, but not normal hearing (NH) people. In the current study we introduce a new algorithm:  Beamformer Cochlear Noise Reduction Algorithm  (BCNRA) which includes a beamformer (the Frost algorithm) followed by CNRA.  BCNRA was evaluated theoretically and experimentally by using a database of 150 Hebrew sentences embedded in different noise types and SNRs. The theoretical evaluation included derivation of Segmental SNR (sSNR) of the input signals, followed by Frost and followed by BCNRA. The analysis yielded a significant improvement in  sSNR of BCNRA relative to Frost especially in those parts of the sentences that did not include speech. In the experimental evaluation subjects were asked to indicate the words they heard while listening to  noisy sentences. The subjects were a group of 10 young normal hearing (NH) people and 10 old HI people who regularly use HAs. In the average the NH yielded an improvement of about 30% in words identification following both Frost BCNRA. On the other hand, the HI yielded an improvement of 30% following Frost and 50% following BCNRA. The benefit of BCNRA to the HI is probably due to its ability to separate words in the noisy sentences.

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SCHOOL OF MECHANICAL ENGINEERING SEMINAR
Tuesday, November 12, 2019 at 13:00
Wolfson Building of Mechanical Engineering, Room 206

Cubic Equations of State and nucleation inception in boiling due to rapid heating
Yarden Amsalem
MSc student of Dr. Tali Bar-Kohany and Prof. Slava Krylov

This study deals with the onset of isobaric boiling for a superheated liquid due to moderate to high heating rates (1.e5.. 1.e9  K/s).
In real liquids, namely liquids that are not specially treated for the removal of possible nucleation sites (such as dissolved gasses, suspended particles etc.), a high level of superheating may be obtained using high heating rates such that the liquid’s nucleation temperature is substantially higher than its saturation temperature; it can reach up to the thermodynamic stability threshold (spinodal).
Prediction of superheat levels and nucleation temperatures under these conditions as a function of temperature change rate has not been possible with analytic tools available today. Despite the fact that the equilibrium boiling temperature (saturation temperature) and the thermodynamic threshold temperature are known for every liquid (although the certainty of the later is less than that of the former) there still lies a difficulty in predicting a liquid’s onset of nucleate boiling (ONB) point within the metastable region.
In the course of this study, 167 data points from relevant (rapid, isobaric) experiments were collected. The experiments were carried out under a pressure of one atmosphere using different liquids: polar (i.e. water, methanol and ethanol) and nonpolar (i.e. heptane and toluene).
A thermodynamic analysis was carried out by using classical thermodynamic potentials while adapting them for use in kinetic processes (quasi-steady). The analysis allowed for the development of a simple correlation which predicts the onset of nucleation boiling conditions for different liquids as a function of their temperature change rate or of the solid interface which heats them. The correlation’s only required inputs are the saturation temperature and the homogenous boiling temperature, both of which are well known quantities.
Owing to its simple mathematical nature, the correlation can be easily applied as a sub-model to any of the existing CFD codes.

Electromagnetic Education and Antenna Technology:
Past, Present and Future
Constantine A. Balanis
School of Electrical, Computer and Energy Engineering, Arizona State University

The field of Electromagnetics (EM) includes theoretical and applied concepts, both of which are described by a set of basic analytical laws, widely acclaimed as Maxwell’s equations.  These laws were formulated primarily through experiments conducted during the nineteenth century by many scientists, and they then were combined into a consistent set of vector equations.  These laws, both in differential and integral form, withstood the test of time for over two centuries, and they have been the foundation of electrical engineering and physics curricula.  They have successfully been applied to numerous problems, and the results have compared favorably with experimental and simulated data.  While there have been no basic changes in the initial structure of these basic laws, there has been an impressive surge in their application, especially during the last 50 or so years.  Because of the dramatic increase in the geometrical complexity of the new problems, whose geometries were not of canonical shapes and could not be described by basic orthogonal coordinate systems, the solutions of most of them could not be derived in closed-form using analytical expressions.  This necessitated the development of numerical methods to solve these complicated problems, whose solutions would otherwise have remained dormant.  The history of EM and its integration to Electrical Engineering curricula will be briefly reviewed.
The genesis of the application of numerical methods to electromagnetics may have started in the 1960s, aided and supported by the advancement of computational resources.  These computational methods and associated software have been integrated in current curricula of Electrical Engineering, both at the undergraduate and graduate levels.  While users are currently highly dependent on these computer codes, we should not lose focus on the interpretation and physical realization of the data simulated using these full-wave solvers.  Therefore, the analytical methods are, and will continue to be, the foundation of electromagnetics and provide understanding and physical interpretation of electromagnetic phenomena and interactions.
Antenna technology has undergone a dramatic evolution from the days of Hertz, with his spark-gap with end-loaded dipole, to today’s high performance Active Electronically Scanned Arrays (AESA) and multiband antennas for smart phones and mobile devices.  The antenna technology reached even greater heights with the introduction and advancements of integrated circuits, solid state technology, unique and creative radiator designs, and signal processing algorithms.  Recently electromagnetic band-gap structures, and the integration of Artificial Magnetics Conductor (AMCs), have begun to play a pivotal role.  Although numerical and computational methods, and associated full-wave simulators, have also contributed to this advancement, basic concepts and fundamental principles in the physical realization, interpretation and verification of designs of simulated should be emphasized.  The timelines over which antenna technology leaped forward are identified, and the various antenna configurations developed during those periods are highlighted.  Future trends in antenna technology are identified and suggested.
On Sunday, November 03, 2019, 14:00
Room 011, Kitot building, Tel Aviv University