סמינר מחלקתי בזום - אלירן רפאל חמו, סטודנט תואר שלישי

10 בנובמבר 2020, 15:00 - 15:40 
ZOOM  
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 סמינר מחלקתי בזום - אלירן רפאל חמו, סטודנט תואר שלישי

סמינר מחלקתי בזום 
PHD Department Seminar
Time: Tuesday, November 10th, 15:00

:You are cordially invited to attend this seminar to be held on 10.11.2020 at 15:00

Stable and Active Catalyst supports Designed based on Transition Metal Carbides for Hydrogen Fuel Cells

Eliran Rephael Hamo, Ph.D. Student

Under the supervision of Dr. Brian Rosen

Polymer electrolyte membrane fuel cells (PEMFCs) are one of the most promising products of the 21st century for power. Their use encompasses portable applications, transportation, and a stationary grid-power mainly due to their low-temperature operation and quick start-up. However, the primary challenge is improving fuel cell durability to meet updated U.S. Department of Energy targets (e.g. 8000+ hours for portable applications). PEM fuel cell catalysts currently suffer from low durability, undermining their wide-scale deployment into the consumer and industrial markets. Platinum is still the most common metal used in PEMFCs as it provides among the highest activity for electrode reactions and lifetime stability. An effective way to decrease Pt loading is the adoption of supports to enhance both Pt dispersion and its utilization. Requirements for such support include factors such as surface area, conductivity, and electrochemical and mechanical stability. Carbon is currently the industrial standard for supporting the Pt catalyst particles, yet carbon-supported catalysts suffer from low durability. Corrosion of the carbon-based support was identified to be the major contributor to performance degradation as they suffer from corrosion via carbon oxidation to CO2 (at the cathode). This phenomenon exacerbates related issues such as Pt sintering or agglomeration. Therefore, there is a significant interest in exploring stable alternatives to replace carbon supports in PEM fuel cells.

Transition metal carbides (TMCs) have attracted significant attention over the last several years as a possible replacement for carbon-based catalyst supports in fuel cells. TMCs exhibit electronic structures similar to Pt-group metals and have been shown to enhance the catalytic activity of fuel cell reactions in part to their strong metal-support interaction (MSI). Despite these advantages over carbon supports, the large-scale deployment of TMC-based supports in fuel cells is still hindered by concerns of durability at the high potential on the cathode during start-up and shutdown operation. Molybdenum carbide in particular has been the center of attention as it imbues high activity for oxygen reduction, yet unprotected Mo2C will begin to oxidize just over 0.4V vs. RHE making them less practical for use as cathode catalysts support.

Here, we modify both the bulk and surface of Pt/Mo2C catalysts and apply them to room-temperature fuel cells which operate under both acidic (as cathode) and alkaline (as anode) environments.  The co-reduction carburization method enabled the low-temperature preparation of TMC alloy supports (e.g. Mo2C-TaC, Mo2C-W2C). By contrast, DC magnetron sputtering was used to modify the surface of the carbide catalysts with Ta-based phases. Bulk alloy formation such as Mo2C-TaC showed enhanced corrosion resistance in acidic fuel cells, yet this came at the expense of activity. By contrast, when the same bulk Mo2C-TaC alloys were employed in alkaline fuel cells (at the anode), increased durability was observed together with increased activity. Experimental and computational efforts by us have shown that durability was attributed to the oxygen binding energy (OBE) of the carbide while activity was attributed to enhanced metal-support interaction, which varied as a function of carbide composition. Despite the fact that bulk alloying with TaC diminished the performance of Pt/Mo2C in acidic fuel cells, the addition of a protective Ta layer to Pt/Mo2C by magnetron sputtering was shown to increase both activity and durability.  Engineering of the support (rather than the metal catalyst) by bulk and surface techniques should therefore be considered as a strategy to simultaneously improve activity and durability in energy conversion and storage systems.

 

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Topic: PHD Department Seminar
Time: Tuesday, November 10th, 15:00
https://us02web.zoom.us/j/85326142774?pwd=ZVRPODI3RTYyc2JFSmNZZi9mbzZPQT09

 

EE Seminar: Generalization in Overparameterized Machine Learning

23 בנובמבר 2020, 15:00 
ZOOM  

Zoom link: https://us02web.zoom.us/j/83932011090?pwd=WjlxK2hOczFvUkQxNy9yQXFLVzJaUT09
Meeting ID: 839 3201 1090
Passcode: TAUEESYS

Speaker: Dr.  Yehuda Dar

Electrical and Computer Engineering Department at Rice University

Monday, November 23rd, 2020, at 15:00

Generalization in Overparameterized Machine Learning

Abstract

            Modern machine learning models are highly overparameterized (i.e., they are very complex with many more parameters than the number of training data examples), and yet they often generalize extremely well to inputs outside of the training set. This practical generalization performance motivates numerous foundational research questions that fall outside the scope of conventional machine learning concepts, such as the bias-variance tradeoff.

This talk presents new analyses of the fundamental factors that affect generalization in machine learning of overparameterized models. We focus on generalization errors that follow a double descent shape with respect to the number of parameters in the learned model. In the double descent shape, the generalization error arrives at its peak when the learned model starts to perfectly fit the training data; but then the error begins to decrease again in the overparameterized regime. Moreover, the global minimum of the generalization error can be achieved by a highly complex (overparameterized) model even without explicit regularization. The first part of the talk considers a transfer learning process between source and target linear regression problems that are related and overparameterized. Our statistical analysis demonstrates that the generalization error of the target task has a two-dimensional double descent shape that is significantly influenced by the transfer learning aspects. Our theory also characterizes the cases where transfer of parameters is beneficial. The second part of the talk introduces a new family of linear subspace learning problems that connect the subspace fitting (using principal component analysis) and regression approaches to the problem. We establish a numerical optimization framework that demonstrates the effects of supervision level and structural constraints on the double descent shape of the generalization error curve.

 

Short Bio

Yehuda Dar is a postdoctoral research associate in the Electrical and Computer Engineering Department at Rice University, working with Prof. Richard Baraniuk on topics in the theory of modern machine learning. Before that he was a postdoctoral fellow in the Computer Science Department of the Technion — Israel Institute of Technology, where he also received his PhD in 2018. Yehuda earned his MSc in Electrical Engineering and a BSc in Computer Engineering, both also from the Technion. His main research interests are in the fields of machine learning theory, signal and image processing, optimization, and data compression.

 

השתתפות בסמינר תיתן קרדיט שמיעה = עפ"י רישום שם מלא + מספר ת.ז.  בצ'אט

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

סמינר המחלקה להנדסה ביו רפואית

Towards personalized neuroimaging in neurosurgery: linking brain networks and cognitive function 

06 בדצמבר 2020, 14:00 
ZOOM  
ללא עלות
סמינר המחלקה להנדסה ביו רפואית

Towards personalized neuroimaging in neurosurgery: linking brain networks and cognitive function 

Abstract: The importance of quality of life of patients following neurosurgery for brain tumors has been increasingly recognized in recent years. Emphasizing the balance between oncological and functional outcome, an emerging discipline at the forefront of research and patient care focuses on cognitive function. In current surgical standard practice, focal electrical stimulation on the exposed brain while patients are awake is used for mapping areas critical for motor function as well as language to prevent irreversible damage as a result of tissue removal. However, some cognitive functions are harder to map with standard stimulation alone. In the talk, I will present my work aimed at developing techniques and tools for mapping cognitive function in neurosurgery. I will focus on a particularly challenging aspect of cognition – executive functions – how we set and achieve goals, make plans, and prioritize tasks, which are essential to all aspects of our everyday life. Because of the complex nature of these functions and the distributed neural systems that support them, there are currently no established techniques for their functional mapping in neurosurgery. I will introduce a novel method that I developed for mapping executive function during awake neurosurgery using electrocorticography (ECOG) – recording directly from the surface of the brain – while patients perform cognitive tasks. I will show evidence for the feasibility and utility of this method as a first step towards establishing its foundations. Critical to bridging the translational gap and bringing neuroimaging into use in neurosurgery is our understanding of the functional role of the neural networks associated with cognitive functions and our ability to identify them in individuals. I will therefore present supporting findings for these using functional MRI (fMRI) data in healthy human volunteers. Finally, I will discuss future research directions towards developing multi-modality neuroimaging with advanced data analysis techniques for personalized medicine in neurosurgery. 
 

Technical Product Manager

  • תואר ראשון / שני בהנדסת חשמל ואלקטרוניקה – חובה
  • ניסיון בהובלת פרויקטים המשלבים חומרה, קושחה, אלקטרו-אופטיקה ותוכנה – חובה
  • בעל.ת 8 שנות ניסיון לפחות בתכנון מעגלים, וידאו, FPGA, ראייה מערכתית – יתרון משמעותי
  • ניסיון בכתיבת מסמכי דרישות ומפרטים לכרטיסים ולמכלולים
  • ניסיון בהובלת ניסויים ואינטגרציות ברמת מכלול / מערכת – יתרון
  • ניסיון בהובלת צוות מטריציוני, מולטי-דיסציפלינארי – יתרון

מהנדס/ת מערכת IR

  • סטודנט.ית מצטיין.ת לתואר במדעים מדוייקים / הנדסה – חובה
  • סטודנט.ית לתואר שני/ בסיום תואר ראשון המתכנן.נת להמשיך לתואר שני / דוקטורט – יתרון
  • יתרת לימודים של שנה וחצי לפחות – חובה
  • שליטה ברמה גבוהה בתוכנת MATLAB – חובה
  • רקע באלקטרואופטיקה ועיבוד תמונה – יתרון
  • שליטה באנגלית טכנית
  • ידע בסיסי בעיבוד אות
  • יכולת למידה מהירה ועבודת צוות

מהנדס/ת לפיתוח אלגוריתמיקה

  • סטודנט.ית לתואר ראשון/שני במדמ"ח/מחשבים/חשמל, בעל יתרת לימודים של שנה וחצי
  • קורסים בעיבוד תמונה – חובה
  • קורסים במערכות לומדות ולמידה עמוקה – חובה
  • יכולת תכנות ב Python – חובה
  • קורסים בניווט ללא GPS , SLAM – יתרון

הנכם מוזמנים לסמינר של מאיר הראל - דוקטורנט - חיפוש אסטרטגיות לבקרת רובוט עבור שימושים בסביבה עם יריב תחת ריבוי קריטריונים

פרטים בהמשך

23 בנובמבר 2020, 14:00 - 15:00 
הסמינר יתקיים בזום  
0
הנכם מוזמנים לסמינר של מאיר הראל - דוקטורנט - חיפוש אסטרטגיות לבקרת רובוט עבור שימושים בסביבה עם יריב תחת ריבוי קריטריוניםסמינר

 

 

"ZOOM" SEMINAR

School of Mechanical Engineering Seminar
Monday, November 23, 2020 at 14:00

 

Multi-criteria Search of Robot Control Strategies for Applications in an Environment with an Adversary

 

by

Meir Harel

Ph.D. student under to supervision of Dr. Amiram Moshaiov

 

Multi-Objective Games (MOGs) are games in which each player has more than one objective to accomplish. Given the multiple objectives, each player may experience a self-conflict about its objective preferences. In recent studies, a novel solution approach to non-cooperative MOGs has been suggested which is termed the rationalizability solution concept. This approach assumes that the players of the MOG are undecided about their objective preferences. Employing the rationalizability approach provides each of the players with a Set of Rationalizable Strategies (SRS). This set exposes the performance tradeoffs among the various rationalizable strategies.

Following the rationalizable solution concept, the current work suggests a modification to the rationalizability solution concept and introduces an approach to reduce the SRS. The suggested modification, which incorporates subjective preferences of the objectives by the players, is based on some Multi-Criteria Decision-Analysis (MCDA) ideas. An evolutionary algorithm, which is based on the introduced modification, is developed. This algorithm results in a reduced SRS which is termed the Set of Preferred Strategies (SPS). The proposed modification is realized by the introduction of auxiliary criteria into the evolutionary search, which could reduce the computational efforts and supports the decision-making.

In addition to modifying the rationalizability approach and the development of the associated algorithms, this work investigates the implementation of the proposed ideas to real-life robotic/dynamic MOGs. For this purpose, a real-life aerial MOG is taken, which involves a navigator and a coalition between the navigation target and a missile that pursuits the navigator. To support solving the aforementioned MOG a novel analytical solution of the problem is introduced. The resulted sets of all possible strategies are analysed using full sorting according to the rationalizability concept. Next, the analytical solution undergoes a numerical modification using neural-networks. The proposed modification undergoes a search using the proposed evolutionary algorithm to produce rationalizable strategies to the original MOG problem. Finally, the resulting control strategies were analysed and examined for their performance characteristics under some changes to the initial conditions of the game.

https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09 The meeting will be recorded and made available on the School’s site.

 

Research Funding Agencies:

 

ISF, BSF, MAFAT, NASA, NIH, NSF, MOST, EU (FP7, Horizon 2020), PAZY Foundation, Israel Innovation Authority

 

הקרן הלאומית למדע

BSF

משרד הביטחון

NASA
NIH

National Science Foundation

PAZY
רשות החדשנות

 

Industrial Sponsorships:

 

Rafael, IAI, Plasan, Edwards, Capvidia-Flowvision, The living heart project, XFlow

 

RAFAEL

IAI

plasan

Edwards

FlowVison

Dassault Systèmes

Dassault Systèmes

 

Junior system engineer

 Responsibilities:

We are looking for and creative system engineers, with profound knowledge in RF systems.

Responsibilities include system design and engineering of our multi-disciplinary projects, technical leadership and interaction with customers.

 Requirements:

הנכם מוזמנים לסמינר של רון הנריק - סטודנט לתואר שני - בחינה מחדש למעבר חום תחת סילון פן-חופשי: ממשטר אדיש להתעוררות מקסימום לא ממורכז.

02 בדצמבר 2020, 15:00 
הסמינר יתקיים בזום  
0
הנכם מוזמנים לסמינר של רון הנריק -סטודנט לתואר שני - בחינה מחדש למעבר חום תחת סילון פן-חופשי: ממשטר אדיש להתעוררות מקסימום לא ממורכז.

 

 

"ZOOM" SEMINAR

School of Mechanical Engineering Seminar
Wednesday, December 2, 2020 at 14:00

Free-surface jet heat transfer reexamined: from indifferent regimes to the re-emergence of off-center peaks

Ron Harnik

Msc of Dr. Herman Haustein

Laminar jet impingement is an efficient method for heat transfer processes, though much of its hydrodynamics and the resulting convection are still not fully understood. In this work, it is shown that, stagnation-point heat transfer depends directly on the near-axis radial acceleration, varying strongly with nozzle diameter, normalized nozzle length, normalized nozzle-to-plate spacing, and flow rate. Studying the hydrodynamics of all stages in the jet’s history up-to plate impingement, therefore, led to the development of a universal heat transfer model.

In this study experiments and two-phase flow simulations were conducted to determine the flow regime of a jet inside a nozzle, during free flight, upon impingement and subsequent wall flow. From the results it was seen that existing theory deals only with two extremes, and therefore a general description is required. Relying on previous pipe-flow analysis by our group, the crucial dynamics of the jet’s centerline velocity decay and evolution of the jet width were dealt with under varying levels of flow rate, issuing velocity-profile development and relaxation, surface tension and gravity. In other words, the dependence of the arriving jet’s key characteristics on all relevant crucial dimensionless numbers (Re, L/d, H/d, We & Fr, accordingly) was addressed. For the jet’s impingement, a previous streamline-bending analysis was adapted to the present case of a free-surface jet, thereby tying the characteristics of the velocity profile arriving at the wall and transitioning from free flight to stagnation flow. The present analysis recovers the radial acceleration’s dictation of stagnation heat transfer, as well as the downstream radial distribution. The model is seen to be valid up to the point of boundary layer emergence from the wall-jet film, beyond which Watson’s classical solution is seen to be valid if appropriately scaled.

Finally, it is seen that the present analysis is physically sound and is able to continuously capture the occurrence or re-emergence of an off-center peak in the heat transfer which occurs for under-developed or over-relaxed arrival profiles – a phenomena previously dealt with only in a case-specific manner. The study has also led to the clarification and definition of a criterion for the occurrence of the “indifferent jet regime” – wherein gravity’s acceleration is countered by the profile relaxation to generate a constant-centerline velocity jet. Such a jet’s stagnation heat transfer is indifferent to the nozzle-to-plate spacing, and has multiple useful applications.

 

Join Zoom Meeting
 

https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09 The meeting will be recorded and made available on the School’s site.

 

 

 

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