LMI Seminar:

Light trapping for broadband absorption of the solar radiation: from nanolenses to light trapping bioinspired by the Fovea Centralis

Dr. Gil Shalev

School of Electrical Engineering

Ben-Gurion University of the Negev

Wednesday  May  25^th,  2022

13:00-14:00

Light refreshments and drinks will be served at 12:30

Auditorium 011, Engineering Classroom Building,  Faculty of Engineering, Tel-Aviv University

Abstract:

 Subwavelength arrays of photoactive materials are important for solar energy applications due to their omnidirectional broadband absorption. Recently, it was suggested and demonstrated how the Yablonovitch 4n2 limit can be surpassed with such systems. We consider three systems of surface silicon subwavelength arrays for light trapping: 1) light trapping bioinspired by the Fovea Centralis (light funnel array paradigm), 2) enhanced light trapping with self-aligned quasi-nanolenses, and 3) light trapping governed by deep subwavelength sidewall decorations. We show that such light trapping approaches conclude an enhancement, in omnidirectional and broadband absorption of the solar spectrum, that is dozens of percent higher compared with state-of-the-art systems. The underlying light trapping mechanisms differ and ranges from refraction, light concentration, scattering, and photon tunneling. The research work is supported with far-field spectroscopy, near-field microscopy and numerical calculations.

Marko, G. et al. (2019). Nano Energy, 61, 275–283. https://doi.org/10.1016/j.nanoen.2019.04.082

Prajapati, A.et al. (2020). Nano Energy, 70, 104521, https://doi.org/10.1016/j.nanoen.2020.104521

Chauhan, A., et al. (2021). Solar RRL, 5(12).

Bio:  Dr. Gil Shalev is a senior faculty member with the school of electrical and computer engineering, Ben-Gurion university of the Negev. His main research interests involve the exploration of novel field-effect devices for bioelectronics and biosensors, light trapping and the broadband absorption of the solar radiation based on arrays of nanostructures for various photonic and photovoltaic applications, and carrier extraction from nano-scaled devices. He gained his scientific education and experience in Tel-Aviv University in Israel and in the Max-Planck Institute for the science of light in Erlangen, Germany.

Globalization of threats to homeland security, such as international terrorism, smuggling of weapons or drugs, or large-scale thefts became one of the main challenges for security forces in the 21st century. In effect, new scientifically grounded methods for fighting organized crime and terrorist threats have been proposed and developed in recent years. One of the rapidly developing research areas are Security Games (SG), which model tactical security issues as games played between security forces and organized attackers. In this talk I will introduce our recently-proposed metaheuristic approach to approximation of the optimal defender’s strategy in general-sum sequential Stackelberg Security Games with imperfect information.

The method (Evolutionary Approach to Security Games - EASG) employs Evolutionary Algorithms with specially designed chromosomes and genetic operators. Experimental evaluation indicates that EASG scales in time and memory better than state-of-the-art MILP (Mixed Integer-Linear Program) methods while providing optimal or close-to-optimal solutions in the vast majority of the cases. Except for competitive time and memory scalability, an additional asset of EASG is flexibility, as the method is generic and largely game-independent. Furthermore, EASG is anytime method, i.e. it can be terminated in any moment and still provide a reasonably good solution, which makes it particularly well suited for time critical SG applications. The talk will also cover several enhancements to the baseline EASG formulation, including an addition of memetic operations (local optimization procedures), the use of two competing populations (co-evolutionary approach), or neuro-evolutionary method in which the attacker’s decision-making model is approximated by a neural network. Application of the above-mentioned approaches to various security scenarios (warehouse patrolling, ferries protection, poaching prevention, cybersecurity) will be presented.

About the Speaker

Prof. J. Mańdziuk received M.Sc. (Honors) and Ph.D. in Applied Mathematics from the Warsaw University of Technology (WUT), Poland in 1989 and 1993, resp., and D.Sc. degree in Computer Science from the Polish Academy of Sciences in 2000.

He is a full professor at the Faculty of Mathematics and Information Science, WUT. His research interests include application of Computational Intelligence and Artificial Intelligence methods to games, dynamic and bilevel optimization problems, and human-machine cooperation in problem solving.

He is also interested in the development of general-purpose human-like learning and problem-solving methods.

For more information please visit http://www.mini.pw.edu.pl/~mandziuk.

Arranging a personal meeting with Prof. Mańdziuk Please contact his host - Dr. Ami Moshaiov at moshaiov@tauex.tau.ac.il

SCHOOL OF MECHANICAL ENGINEERING SEMINAR

Monday. May 15, 2022 at 14:00

ZOOM SEMINAR

Biomechanics of Insect Adhesion

Prof. Walter Federle

University of Cambridge

Many insects, spiders, frogs and lizards are able to climb on smooth plant and rock surfaces with the help of special attachment organs, which are substrate-tolerant, wear-resistant, self-cleaning and controllable, making them promising models for biomimetics.
Adhesive pads of climbing animals are shear-sensitive (directional), allowing rapid detachment during locomotion. Shear-sensitivity of adhesion is achieved by diverse mechanisms at the level of whole body, legs, cuticle and adhesive secretion. Insects have developed special adaptations for controlling adhesion when jumping from smooth plant surfaces, or clinging to rocks underwater with suction organs. Many plants have evolved surfaces that are slippery to insects due to wax crystals or lubricating liquid films. Some insects have developed remarkable counter-adaptations to climb safely on these slippery plants.

Walter Federle is Professor of Comparative Biomechanics at the Department of Zoology, University of Cambridge, UK. Following his PhD from the University of Würzburg (Germany), and postdoctoral fellowships at Harvard University and UC Berkeley (USA), he joined the University of Cambridge in 2005. His research focuses on insect and plant biomechanics, and attachment mechanisms in nature.

Join Zoom Meeting https://us02web.zoom.us/j/82108132163?pwd=Z2h4UzNzUS9mbXplT0lMU1pZenFEQT09

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להתנסות במגוון תפקידים, לחוות תחומים שונים וליהנות מהידע של האנשים הטובים ביותר. 
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ביום שלישי הקרוב 17.05 בין השעות 11:00-13:00 מחוץ לבניין וולפסון

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