הפקולטה להנדסה ע"ש איבי ואלדר פליישמן

סמינר המחלקה להנדסת תעשייה

29 בדצמבר 2020, 14:00

zoom

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Recovering tree models via spectral graph theory

Ariel Jaffe is a Gibbs assistant professor in the program of applied mathematics, Yale University
The lecture will be heldon
Tuesday, December 29, 2020, at 14:00 Via Zoom
https://us02web.zoom.us/j/81941109328?pwd=Z04rVGltdmI1Qm5jQjZEZWtwNDgvUT09

Abstract:
Modeling high dimensional data by latent tree graphical models is a common approach in multiple machine learning
applications. In these models, the key task is to infer the structure of the tree, given only observations on its terminal
nodes. A canonical example of this setting is the tree of life, where the evolutionary history of a set of organisms is
inferred by their nucleotide or protein sequences.
In our work, we show that the tree structure is strongly related to the spectral properties of a fully connected graph,
defined over the terminal nodes of the tree. This relation forms the theoretical basis of two new methods to recover
latent tree models: (i) spectral neighbor joining, where subsets of nodes are iteratively merged to form the full tree,
and (ii) spectral top down recovery, where the terminal nodes are iteratively partitioned into smaller subsets.
Comparing our approach to several competing methods, we show that in many settings, spectral methods have
stronger theoretical guarantees and work better in practice.

Bio:
Ariel Jaffe is a Gibbs assistant professor in the program of applied mathematics, Yale University.
Previously, he completed his Ph.D. in the Weizmann Institute of Science under the guidance of Prof. Boaz Nadler.
His research interests include statistical machine learning and high dimensional data analysis, with a focus on
applications in the fields of computational biology and signal processing.

דקאן הפקולטה - פרופ' נעם אליעז ראשת המנהל - גב' הילה אלוני

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הנכם מוזמנים לסמינר של קרין לוי - סטודנטית לתואר שני - פיתוח סוללת ליתיום תיוניל-כלוריד עם קתודת פחם ללא שימוש באיזופרופנול, תוך שמירה על ביצועיה החשמליים.

11 בינואר 2021, 14:00 - 15:00

הסמינר יתקיים בזום

הנכם מוזמנים לסמינר של קרין לוי - סטודנטית לתואר שני - פיתוח סוללת ליתיום תיוניל-כלוריד עם קתודת פחם ללא שימוש באיזופרופנול, תוך שמירה על ביצועיה החשמליים.

"ZOOM" SEMINAR

School of Mechanical Engineering Seminar
Monday, January 11, 2021 at 14:00

Development of a lithium thionyl-chloride battery with a carbon cathode produced without isopropanol

Karin Levi

MSc Under the supervision of Prof. Naima Brauner

Lithium batteries have come a significant long way in the past decades. The batteries have changed from a product of curiosity to a dominant product to variety of consumers, such as medical equipment, water meters and so on. The electrical performance of a lithium thionyl-chloride battery is greatly influenced by the carbon cathode, on which the chemical reaction is carried out between the lithium ions and the thionyl-chloride ions. Consequently, the structure, size, and physical properties, such as porosity of the cathode, are very important.

An essential component used in the manufacturing of the currently used cathode is Isopropanol. It helps achieving the necessary wetness of the carbon, resulting in a homogenous slurry while mixing with water and Teflon. Isopropanol is a colorless, flammable chemical compound with a strong odor. Therefore, it must be used under strict safety rules. Moreover, isopropanol is considered environmental pollutant and the European standard TA LUFT (adopted in Israel), allows max of 50 mg/m^3.

The properties of cathodes produced with and without Isopropanol and the difficulties during manufacturing are described. In addition, the effect of the new cathode on the batterie's capacities and voltages are presented and discussed. It is argued that the significant advantage of a cathode without isopropanol is the porous structure. This structure allows a better adsorption of the electrolyte solution. The presence of more active sites allows more precipitation of reaction products, and an increase in the anode area in front of the cathode. The results of this research showed that the electrical performances of lithium chloride batteries were not affected using a cathode without Isopropanol and the electrical performances were even improved.

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https://zoom.us/j/96584758181?pwd=WC9PMXdsYzJ3NFdEN2Q5ZUtOZEVjdz09