סמינר מחלקתי של ישראל קלרשטיין- עקרונות עיצוב היררכי עבור חומרים ביו-מרוכבים רב-תכליתיים

23 בדצמבר 2024, 14:00 - 15:00 
 
סמינר מחלקתי של ישראל קלרשטיין- עקרונות עיצוב היררכי עבור חומרים ביו-מרוכבים רב-תכליתיים

Hierarchical Design Principles for Multifunctional Biocomposites

Monday December 23th at 14:00 

Wolfson Building of Mechanical Engineering, Room 206

 

Abstract:

Balancing strength and toughness remains a fundamental challenge in designing structural materials, as these properties are inherently contradictory. Overcoming this trade-off is essential for creating damage-tolerant materials capable of meeting rigorous structural demands. In the first part of my talk, I will present my past research on biological materials, focusing on their hierarchical organization and multiscale mechanical properties. I will highlight structural strategies that can be applied to engineering composites to address the strength-toughness conflict. In the second part, I will discuss how biological principles have guided the development of sustainable materials. Using a bottom-up fabrication approach, structural hierarchy was integrated to achieve enhanced mechanical performance and multifunctionality in engineered biocomposites. Biological materials inherently solve the strength-toughness challenge through evolved design principles. By understanding and applying these principles, we can develop the next generation of damage-tolerant composites, advancing structural performance to unprecedented levels.

 

Bio:

Israel Kellersztein is a postdoctoral scholar and Fulbright Fellow in the Department of Mechanical and Civil Engineering and the Resnick Institute for Sustainability at Caltech. He earned his Ph.D. from the Weizmann Institute of Science in 2020 and completed his M.Sc. in Plastics and Polymer Engineering from Shenkar College, in a direct track. His research lies at the intersection of natural materials science and advanced manufacturing. His research focuses on understanding the multiscale mechanics of biological composites and leveraging these insights to design structural bioinspired composites with enhanced damage tolerance.

סמינר מחלקתי של אורן גל- לקראת נחילים חכמים יותר: אופטימיזציה של דפוסי חיפוש ו חקר עם מסגרות מונעות בינה מלאכותית

16 בדצמבר 2024, 14:00 - 15:00 
 
סמינר מחלקתי של אורן גל- לקראת נחילים חכמים יותר: אופטימיזציה של דפוסי חיפוש ו חקר עם מסגרות מונעות בינה מלאכותית

Towards Smarter Swarms: Optimizing Search Patterns and

Exploration with AI-Driven Frameworks

Monday December 16th at 14:00 

Wolfson Building of Mechanical Engineering, Room 206 

Abstract:

This research investigates the performance and efficiency of multi-agents in multi-target tracking scenarios using the Adaptive Particle Swarm Optimization with k-Nearest Neighbors (APSO-kNN) algorithm. The study explores various search patterns-Random Walk, Spiral, Lawnmower, and Cluster Search to assess their effectiveness in dynamic environments. Through extensive simulations, we evaluate the impact of different search strategies, varying the number of targets and agent’s sensing capabilities, and integrating a Pursuit-Evasion model to test adaptability. Our findings demonstrate that systematic search patterns like Spiral and Lawnmower provide superior coverage and tracking accuracy, making them ideal for thorough area exploration. In contrast, the Random Walk pattern, while highly adaptable, shows lower accuracy due to its non-deterministic nature, and Cluster Search maintains group cohesion but is heavily dependent on target distribution. The mixed strategy, combining multiple patterns, offers robust performance across varied scenarios, while APSO-kNN effectively balances exploration and exploitation, making it a promising approach for real-world applications such as surveillance, search and rescue, and environmental monitoring. This study provides valuable insights into optimizing search strategies and sensing configurations for swarms, ultimately enhancing their operational efficiency and success in complex environments.

On the second part of this talk, we address the challenge of exploring unknown indoor environments using autonomous aerial robots with Size Weight and Power (SWaP) constraints. The SWaP constraints induce limits on mission time requiring efficiency in exploration. We present a novel exploration framework that uses Deep Learning (DL) to predict the most likely indoor map given the previous observations, and Deep Reinforcement Learning (DRL) for exploration, designed to run on modern SWaP constraints neural processors. The DL-based map predictor provides a prediction of the occupancy of the unseen environment while the DRL-based planner determines the best navigation goals that can be safely reached to provide the most information. The two modules are tightly coupled and run onboard allowing the vehicle to safely map an unknown environment. Extensive experimental and simulation results show that our approach surpasses state-of-the-art methods by 50-60% in efficiency, which we measure by the fraction of the explored space as a function of the trajectory length.

 

Bio:

Oren received my B.Sc. in Aerospace Engineering, M.Sc. degree in Mechanical Engineering and a Ph.D. in Geo-information Engineering, all from the Technion – Israel Institute of Technology. Oren is currently an Assistant Professor, heading the Swarm and AI (SAIL) Lab, at the Hatter Department of Marine Technologies. Prior to joining the University of Haifa, Oren was the founder and CTO of Autonomy & Data Science R&D in the Israeli Navy (CDR Ret.) and DDR&D for twenty years, working with research partners around the world and leading research groups (DARPA, ARL, NRL, ONR etc). In the last ten years, he is working on joint research with CSAIL & LIDS MIT labs and with Marine Robotics Lab at MIT, UPenn, all on swarms and machine learning algorithms.

Oren’s research focus on swarms and AI across scales. The adaptability and scalability of swarms make them particularly suited to tasks that require distributed sensing, acting, and processing, presenting numerous possibilities for addressing complex and large-scale challenges facing humanity. From nanorobots for cancer treatment, to environmental monitoring and conservation in the ocean, or disaster response and recovery, traffic management and logistics etc. - swarms, particularly swarm intelligence of AUVs, USVs and drones.

In our cutting-edge research lab, Oren’s research delve into the complex and rapidly evolving field of swarms and autonomy, leveraging the latest advancements in Artificial Intelligence (AI) to push the boundaries of autonomous systems across scales.

סמינר מחלקתי של נתן פרצ'יקוב- מכניקת מוצקים לא-לינארית חישובית: HPC, הומוגניזציה ופלסטיות גבישים מזוסקופית

09 בדצמבר 2024, 14:00 - 15:00 
 
סמינר מחלקתי של נתן פרצ'יקוב- מכניקת מוצקים לא-לינארית חישובית: HPC, הומוגניזציה ופלסטיות גבישים מזוסקופית

Computational nonlinear solid mechanics: HPC, homogenization and mesoscopic crystal plasticity

Monday December 9th at 14:00 

Wolfson Building of Mechanical Engineering, Room 206

Abstract:

In this seminar a computational (finite-element) model for fundamental mesoscopic analysis of plastic deformation in crystalline metals is presented, summarizing research conducted in the CNRS, France, on an ANR grant. In this approach, every element represents a continuous chunk of a single crystal that undergoes large stretches and rotations and is described by an energy functional periodically dependent on simple-shear strains, which represent energetically equivalent elastic states differing only by the extent of plastic deformation that has accumulated. In turn, the plastic deformation is quantized, staying a multiple of the discrete shift associated with a single crystal-lattice-space slip. In this approach, the medium is first considered elastic and is loaded by a single loading increment, with equilibrium obtained standardly, using correctly defined tangent moduli. Subsequently, the yield criterion is examined, and if violated, plastic flow is initiated in a quantized manner, meaning that an integer multiple of a single lattice slip is implemented sequentially, until first complying with the yield conditions. In turn, the yield conditions are derived from the group symmetry of the single-crystal lattice, rather than by relying on phenomenology, like one does for effectively isotropic polycrystals. The group-symmetry condition simply means that if a simple shear had extended more than halfway the lattice spacing, the stable configuration shifts by one lattice space and plastic strain is updated by unity in the appropriate direction. When treating a polycrystal in such a way, every single-crystal grain is divided into finite elements, and in each plasticity is treated fundamentally, with symmetry-related geometric yield and quantized plastic flow. Then, the overall response is obtained by numerical homogenization. This provides an alternative for phenomenological plasticity of polycrystals. Interestingly enough, when simulating the loading of a single crystal in simple shear up to and beyond the principal instability, one observes symmetry breaking. The loading remains positive but the internal stress becomes negative, which implies loss of static stability and inertial energy dissipation. The corresponding dynamic process involves a dynamical system undergoing synchronization. The dynamic synchronization produces aligned chunks of elements, reminiscent of grains. Coarse-grained response and critical exponents of statistical fluctuations are validated against experiments and theoretical studies. In addition, a short account of another project is given, one conducted in the Max-Planck Institute, Germany, for a DFG grant, dedicated to high-performance computing (HPC) in homogenization of the stress response of polycrystalline steels. The project involved the development of a new spectral solver in polar coordinates, for sublinear-runtime stress analysis in composites and polycrystals on parallel processors, yielding lower induced anisotropy and boundary effects when compared to Cartesian solvers.

bio:

Nathan Perchikov has obtained his MSc degree in the direct track in the School of Mechanical Engineering at Tel Aviv University, with a thesis on optimal rib-stiffening of rectangular plates in elastostatic bending, under the guidance of Prof. M.B. Fuchs. He later obtained his PhD degree in Nonlinear Dynamics at the Faculty of Mechanical Engineering at the Technion, under the guidance of Prof. O.V. Gendelman. Subsequently, he was a postdoctoral researcher at the Sorbonne Université in Paris, France, at the CNRS Lab PMMH. He was also a postdoctoral researcher at the Max-Planck Institute for Iron Research in Germany. Other scientific collaborations include the Chemical Physics department at the Weizmann Institute of Science, the École Polytechnique Fédérale de Lausanne in Switzerland, and the City University of New York, in addition to a 10-years long collaboration with Prof. J. Aboudi from the SME at TAU

סמינר מחלקתי של קמילה סמרטינו- זרימת נוזלים כיוונית ספונטנית במבנים טופולוגיים בהשראת ביו

02 בדצמבר 2024, 14:00 - 15:00 
 
סמינר מחלקתי של קמילה סמרטינו- זרימת נוזלים כיוונית ספונטנית במבנים טופולוגיים בהשראת ביו

Spontaneous Directional Liquid Flow in Bio-Inspired Topological Structures

Monday November 18th at 14:00 

Wolfson Building of Mechanical Engineering, Room 206

 

abstract:

In nature, several organisms possess the extraordinary ability to guide liquids to specific places spontaneously. Trees, cactus spines, spider silk, desert lizard scales, and fleas are just some fascinating examples. Surfaces geometries combined with surface chemistries that promote directional liquid flow gained the term “liquid diodes”. Applications of such liquid diodes range from microfluidics and electronics to biomedicine and sensing. However, an in-depth understanding of how liquids spread and flow in complex networks of such liquid diodes still lacks.

In this work, the functionality, performance, and applications of liquid diodes inspired by the spermatheca organ found in female fleas were studied. High resolution 3D printing was used to design complex geometries and elucidate how liquid propagates in 2D networks made of liquid diodes. This includes flexible liquid diodes in which liquid flow can be mechanically actuated.

Finally, additional work on spontaneous unidirectional flow in asymmetric hollow structures and 3D meshes is presented. Drawbacks and future steps are discussed.

This research work highlights the emerging potential of liquid diodes as versatile tools for manipulating and modelling liquid flow in both technical and biological systems. Furthermore, it offers new opportunities in applications such as lab-on-a-chip devices, sensing, wearable electronics, and space aviation where fine control over fluid dynamics is crucial.

 

bio:

Camilla, originally from Milan, Italy, graduated in Physics in 2017 from Università degli Studi di Milano and moved to Israel the following year for her Master's degree in Materials Science and Engineering. During her MSc, she worked on metal laser-assisted 3D printing under the supervision of Prof. Noam Eliaz and in collaboration with Orbotech (now part of KLA). After graduating in 2021, she started her Ph.D in Dr. Bat-El Pinchasik's group, Biomimetic Mechanical Systems and Interfaces. She works on spontaneous directional liquid transport on bioinspired topological surfaces. 

 

סמינר מחלקתי של דנה סולב- התקני הליכה מסייעים ספציפיים למטופל: עיצוב וניתוח מבוססי נתונים

25 בנובמבר 2024, 14:00 - 15:00 
 
סמינר מחלקתי של דנה סולב- התקני הליכה מסייעים ספציפיים למטופל: עיצוב וניתוח מבוססי נתונים

 

Patient-Specific Weight-Bearing Assistive Gait Devices: Data-Driven Design and Analysis

Monday November 25th at 14:00 

Wolfson Building of Mechanical Engineering, Room 206

Abstract:

Various weight-bearing assistive gait devices, such as lower-limb prosthetics and orthotics, require a tailored patient-specific design. This is crucial for ensuring proper mechanical interaction with soft tissues and facilitating functionality. However, the conventional methods for custom design are largely artisanal, non-standard, and insufficiently data-driven. Therefore, there is a clear need for computational design frameworks that are automatic, repeatable, data-driven, and based on scientific rationale. These frameworks typically utilize imaging techniques, sensors, and numerical simulations such as finite element analysis (FEA), to drive patient-specific design.

This talk will cover two research projects aimed at advancing the development of these frameworks. The first project concerns the development of a new type of ankle-foot orthosis (AFO) for walking with adjustable ankle-foot offloading. This AFO aims to facilitate a symmetric and natural gait pattern while precisely adjusting the amount of load transferred to the injured foot and ankle during gait. It incorporates a patient-specific load-bearing shank brace, and ground contact plates based on a statistical analysis of ankle-foot roll-over shape. The second project focuses on estimating the material parameters of soft tissues used in FEA simulations for design algorithms. Accurate constitutive modelling and parameter estimation are crucial for reliable FEA results. However, it is challenging to identify these parameters in vivo, and uncertainties can propagate into the simulated results. We will discuss methods to improve the identifiability of material parameters that capture the complex mechanical responses of soft tissues, using multi-modal indentation tests.

 

 

 

Bio:

Dr. Solav holds a BSc in Geophysics from Tel-Aviv University (2006) and a PhD in Mechanical Engineering from the Technion - Israel Institute of Technology (2016). In 2017 she joined the MIT Media Lab’s Biomechatronics group as a postdoc, where she became a research scientist (2019) to lead the group’s computational biomechanics research track. In 2020, Dr. Solav joined the Technion’s Faculty of Mechanical Engineering as an Assistant Professor, where she currently directs the Biomechanical Interfaces Group. Her research focuses on the biomechanical interface between the human body and biomedical devices such as prosthetics and orthotics, with an emphasis on developing and optimizing patient-specific devices that improve patient comfort, health, and function. To achieve this, Dr. Solav’s group analyzes the biomechanical factors that affect human movement and function, develops new imaging and measurement tools, and combines them with advanced computational algorithms, experimental procedures, and fabrication methods.

סמינר מחלקתי של יואב לחיני- ביקורתיות המפולת מניעה את ההזדקנות הפיזית של חומר מופרע: מסדינים מקומטים ועד רעידות משנה סיסמיות

18 בנובמבר 2024, 14:00 - 15:00 
בית ספר להנדסה מכנית  
סמינר מחלקתי של יואב לחיני- ביקורתיות המפולת מניעה את ההזדקנות הפיזית של חומר מופרע: מסדינים מקומטים ועד רעידות משנה סיסמיות

 

Avalanche Criticality Drives the Physical Aging of Disordered Matter:

from Crumpled Sheets to Seismic Aftershocks

Monday November 18th at 14:00 

Wolfson Building of Mechanical Engineering, Room 206

Abstract:

Many complex and disordered systems fail to reach equilibrium after they have been quenched or perturbed. Instead, they sluggishly relax toward equilibrium at an ever-slowing, history dependent rate, a process termed physical aging. The microscopic processes underlying the dynamic slowdown during aging and the reason for its similar occurrence in different systems remain poorly understood.

Combining experiments on crumpled sheets and simulations of a disordered network of interacting elastic instabilities, we reveal the structural mechanism underlying logarithmic aging in these systems. We find that under constant external loading, the system self-organizes to a marginally stable state, where it can remain for long, but finite, times. The system’s slow relaxation is intermittent, and advances via self-similar, slow avalanches of localized, micro-mechanical instabilities.

These avalanches are thermal – they span many timescales and are driven by facilitation and noise. The avalanches’ size and the inter-instability times are power-law distributed and exhibit a unique property – the distributions maintain their scaling exponents throughout the ageing process, but their cut-offs grow in time. Crucially, the quiescent dwell times between avalanches grow in proportion to the system’s age, which leads to the observed dynamic slow-down and logarithmic aging. We link this effect to a slow increase of the lowest local energy barriers, which we find govern the initiation of avalanches.

Applying our analysis to the temporal dynamics of seismic aftershocks reveals strikingly similar results, suggesting that a similar physical mechanism underlies aftershock dynamics and the celebrated phenomenology of Omori’s law.

 

 

:Bio

Yoav Lahini earned a B.Sc. in physics from the Hebrew University, and an M.Sc. and PhD in Physics from the Weizmann Institute, working on nonlinear and quantum optics in disordered media. He then spent three years at MIT as a Pappalardo postdoctoral fellow and two additional years at Harvard as a research associate, working on the far-from-equilibrium dynamics of complex and disordered systems. In 2017 Yoav opened the Soft and Complex Matter Lab in the school of Physics at Tel Aviv university.

 

EE Seminar: Undetectable Watermarks for Language Models

18 בנובמבר 2024, 12:00 
אולם 011  
EE Seminar: Undetectable Watermarks for Language Models

(The talk will be given in English)

 

Speaker:     Dr. Or Zamir

                             School of Computer Science, Tel Aviv University 

 

011 hall, Electrical Engineering-Kitot Building‏

Monday, November 18th, 2024

12:00 - 13:00

 

Undetectable Watermarks for Language Models

 

Abstract

Recent advances in the capabilities of large language models such as GPT-4 have spurred increasing concern about our ability to detect AI-generated text. Prior works have suggested methods of embedding watermarks in model outputs, by noticeably altering the output distribution. We ask: Is it possible to introduce a watermark without incurring any detectable change to the output distribution?

To this end we introduce a cryptographically-inspired notion of undetectable watermarks for language models. That is, watermarks can be detected only with the knowledge of a secret key; without the secret key, it is computationally intractable to distinguish watermarked outputs from those of the original model. In particular, it is impossible for a user to observe any degradation in the quality of the text. Crucially, watermarks should remain undetectable even when the user is allowed to adaptively query the model with arbitrarily chosen prompts. We construct undetectable watermarks based on the existence of one-way functions, a standard assumption in cryptography.

We will also cover subsequent generalizations to steganography, and robust versions.

 Short Bio

Or Zamir is an assistant professor at the school of computer science in Tel Aviv University. Prior to that, he did his postdoc at the Institute for Advanced Study and Princeton University. His research interests include algorithms, data structures, and theoretical computer science. 

 

השתתפות בסמינר תיתן קרדיט שמיעה = עפ"י רישום שם מלא + מספר ת.ז. בטופס הנוכחות שיועבר באולם במהלך הסמינר

 

 

 

Physical Electronics Seminar : Building blocks for nanoscale magnetic resonance imaging

סמינר שמיעה לתלמידי תואר שני ושלישי

14 בנובמבר 2024, 11:00 
Room 011 Kitot Building  
  Physical Electronics Seminar : Building blocks for nanoscale magnetic resonance imaging

 

  -סמינר זה יחשב כסמינר שמיעה לתלמידי תואר שני ושלישי-  This Seminar Is Considered A Hearing Seminar For Msc/Phd Students-

 

 

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