Electrical Engineering Colloquium 

Speaker: Dr. Ilai Bistritz

Title: It's Just a Game: Designing Distributed Multiagent Protocols

Abstract 

Automation relegates many decision-making processes from humans to machines. In recent years, automation is powered by machine learning, which enables trained machines to achieve expert-level performance in some tasks. Many of these tasks require humans to interact (e.g., driving, delivery, construction), so automating them will result in interacting machines where the decisions of one machine affect others. As game theory predicts, this interaction can lead to a globally inefficient equilibrium. However, machines follow programmatic objectives and protocols that, unlike humans, are not limited by selfish interests, but by information and resources. This modern paradigm calls for new tools to design efficient multiagent protocols.
 
We will first highlight the major design challenges and then discuss the distributed energy allocation problem as a concrete example. We formulate this problem as a game and study the performance of best-response dynamics (BRD) as a distributed algorithm that the sources run to allocate energy to consumers. We show that  "bad networks" exist where BRD suffers from poor performance. However, empirically, these bad networks are rare. Drawing inspiration from this empirical finding, we analyze BRD as a random process in a random game. We show that, with high probability, BRD is asymptotically optimal (in the size of the network). Applying our “random games approach” broadly may reveal that BRD is efficient more often than the worst-case overly pessimistic approach would suggest. This is an encouraging finding since BRD requires little to no coordination between the agents.

Light refreshments will be served before the lecture

This colloquium is not counted toward seminar credit.

ההרצאה לא מזכה בקרדיט שמיעת סמינרים.

יום פרוייקטים במחלקה לחשמל- שמרו את התאריך ה27.06

הנכם.ן מוזמנים.ות ליום פרוייקטים בחשמל שיערך ביום שלישי ה27.06.23 ויתקיים בפקולטה להנדסה בבניין כיתות חשמל. 

נשמח לראותכם בין אורחינו,

ארגון עמיתי התעשייה והמחלקה לחשמל מהפקולטה להנדסה. 

לינק להזמנה

School of Mechanical Engineering Seminar
Monday, June 26, 2023, at 14:00
Wolfson Building of Mechanical Engineering, Room 206

Invariant Echo-Localization Using Bat Pinnae (External Ear)

Zahi Cohen

M.Sc. Student of Prof. Yossi Yovel

School of Mechanical Engineering Seminar
Wednesday June 21.6.2023

Wolfson Building of Mechanical Engineering, Room 206

Multi-phase PHFGMC micromechanical models for C/C-SiC based Ceramic Matrix Composites

Chen Dahan Sharhabani

M.Sc. research under the supervision of Prof. Rami Haj-Ali Tel Aviv University, Department of Mechanical Engineering

New advanced carbon-based Ceramic Matrix Composites (CMCs) are a novel class of materials that overcome the oxidation encountered in C/C applications, including hypersonic systems. CMCs inhibit good mechanical properties (relative to C/C), favorable damage tolerance (Compared to ceramics), and relatively low density. This cluster of properties advances the use of CMCs in high-temperature aerospace, energy, and transport applications, where an oxidation environment is present. The properties of fiber-reinforced ceramics depend strongly on their microstructure and composition. In addition, CMC final thermomechanical properties depend strongly on fiber and ply architecture and the manufacturing parameters controlling the different thermal steps used during manufacturing.

An iterative material design development and manufacturing, followed by material characterizations and evaluations, can be cost-prohibitive and requires a longtime approach. This study advocates using predictive micromechanical models in CMC material design to reduce cost and design time cycle. Most micromechanical models consider the phases that inhibit the composite material and can perform average or equivalent properties over the volume of the phases. More advanced and refined micromodels recognize and account for several microstructural details, including dominant phases and their interface (or interphase) parameters. These refined models should be capable of nonlinear and damage predictions and can be readily used to study the effect of porosity (or voids) on elastic behavior. 

The current study introduces a refined micro-modeling framework that recognizes several material and microstructural details of the CMC material using the parametric high-fidelity generalized method of cells (PHFGMC). The PHFGMC can attain high-accuracy solutions for realistic physical problems of composite materials and allows the nonlinear thermomechanical solution for multiscale and multi-phase three-dimensional problems. 

 A two-level hierarchical framework based on the PHFGMC micromechanical model is implemented using CT-based C/C-SiC ceramic matrix composite scan geometries. Towards that goal, two nested PHFGMC micromechanical models are nested and integrated to represent the CMC micro and meso material levels.   The proposed framework enables a realistic depiction of the material structure and allows for calculating the effective orthotropic properties of a single lamina. The proposed modeling can be used to design a broad class of CMC materials with different weave architectures. Our PHFGMC prediction results were compared to mechanical properties conducted in collaboration with Rafael's advanced material lab for the tensile behavior of CMC specimens. The proposed PHFGMC framework demonstrated good prediction results.

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