הפקולטה להנדסה ע"ש איבי ואלדר פליישמן

Departmental Seminar - Materials Science and Engineering: Prof. David Eisenberg

15 במאי 2017, 15:00 - 16:00

בניין וולפסון, חדר 118

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Departmental Seminar: Materials Sciences and Engineering

Prof. David Eisenberg

Schulich Faculty of Chemistry, Technion – Israel Institute of Technology

Rational design of microstructure, composition, and electrocatalysis in carbon materials

Carbon materials – highly porous, partially graphitic, and hetero-doped – are rising electrodes in electrochemical devices for energy storage. This is a curious twist of history: for many millennia carbon was mostly a low-value energy source, only good for burning up. These days, we find carbon electrodes in power sources as diverse as batteries, fuel cells and supercapacitors. The microstructure of such carbons – affecting much of their electrochemical function – is hard to design and control. We have recently reported a family of N-doped, hierarchically porous carbons, whose structure and composition can be tuned rationally, opening the way to in-depth studies of structure–activity links. These carbons are derived from metal-organic frameworks (MOFs), whose composition can be controlled and correlated to the final carbon structure, and ultimately, electrocatalytic properties. This talk will discuss design principles of carbon-based electrocatalysis, focusing on elegance of synthesis, separation of structural variables, and understanding electrocatalytic function.

Full Invitation

Departmental Seminar - Materials Science and Engineering: Oded Pinkas

03 באפריל 2017, 15:00 - 16:00

בניין וולפסון, חדר 118

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COMPOSITE HYDROGELS FOR BIOADHESIVE AND SURGICAL SEALANT APPLICATION

Oded Pinkas

Under the supervision of

Prof. Meital Zilberman

Bioadhesives are polymeric hydrogels that can adhere to a tissue after crosslinking and are an essential element in nearly all surgeries worldwide. The use of bioadhesives and sealants for wound closure and healing applications is becoming more and more popular, particularly when other techniques, such as stapling or suturing, are impractical or inefficient. The main limitation of current tissue adhesives is the tradeoff between biocompatibility and mechanical strength, especially in wet hemorrhagic environments.

Therefore, the current research focuses on the development and study of novel bioadhesives based on a combination of the biopolymers gelatin with alginate and crosslinked with carbodiimide. Furthermore, the bioadhesives are incorporated with hemostatic agents (tranexamic acid, kaolin and montmorillonite) in order to induce hemostatic effects, improve the adhesion abilities in the hemorrhagic environment of the wound and to increase the cohesion strength. Such bioadhesives are novel, have not been developed and studied before and are not available in the market. The effect of the bioadhesive's components on the mechanical strength was studied by four different methods - burst strength, lap shear strength, tensile strength and elastic modulus in compression. The physical properties were evaluated by the viscosity, gelation time, swelling ratio and weight loss. The structural features of the bioadhesive were studied by environmental scanning electron microscopy and X-ray diffraction. The cytotoxicity of the bioadhesive was evaluated in extraction mode. Our bioadhesive formulations present excellent mechanical properties and superior to those commercial bioadhesive. The incorporation of the functional fillers in the polymeric matrix resulted in special microcomposites and nanocomposites that improves the bioadhesive's function and properties. The formulation-structure-property effects of our novel bioadhesives will be presented in the seminar.

Full Invitation

EE Seminar: Network Intrusion Detection for SCADA Systems

Speaker: Amit Kleinmann

Ph.D. student under the supervision of Prof. Avishai Wool

Wednesday, April 5^th, 2017 at 15:00
Room 011, Kitot Bldg., Faculty of Engineering

Network Intrusion Detection for SCADA Systems

Abstract

SCADA systems are command and control systems integrated in industrial facilities that have a strategic significance due to the great damage consequences of any fault or malfunction. SCADA systems were originally created to be deployed in non-networked environments and thus they lack of adequate security against Internet based threats and cyber-related forensics.

Protecting SCADA systems is a unique challenge. The objective of this research was to improve the current state of intrusion detection for SCADA networks. In certain scenarios of SCADA communication, the network traffic is the result of several multiplexed cyclic patterns. We propose to model this type of traffic as a Statechart of multiple DFAs. The Statechart approach is very sensitive and is able to flag anomalies such as a message appearing out of position in the normal sequence or a message referring to a single unexpected bit.

We also suggest unsupervised learning algorithms to automatically build the Statechart DFA. These algorithms identify the number of cycles and learn each of the multiplexed cyclic patterns even in cases where there are symbols that appear more than once in a cycle, or symbol overlaps between different patterns.

Finally, we developed several attack scenarios against real SCADA equipment.

Our stealthy network-based attacks operate by hijacking the SCADA communication channels, manipulating the traffic so as to present the human operator a fabricated view of the industrial process, and tricking her into taking inappropriate and damaging manual actions. All our multi-stage semantic attacks successfully fooled the operator, and brought the system to states of blackout and possible equipment damage.

An important aspect of this research is that the proposed intrusion detection

approach was evaluated using real traffic from production SCADA networks. Our experiments demonstrate that the Statechart DFA anomaly detection model handles SCADA traffic patterns very well. With systems that implement this model in place, attackers are restricted to only mount super-stealthy deception attacks like ours, and cannot mount simpler and more direct attacks without risk of detection. Thus we provide a solid basis for practical anomaly detection systems.

05 באפריל 2017, 15:00

חדר 011, בניין כיתות-חשמל

EE Seminar: A New Approach to Model Pitch Perception Using Sparse Coding

Speaker: Oded Barzelay

Ph.D. student under the supervision of Prof. Miriam Furst and Omri Barak

Wednesday, April 19^th, 2017 at 15:00
Room 011, Kitot Bldg., Faculty of Engineering

A New Approach to Model Pitch Perception Using Sparse Coding

Abstract

Our acoustical environment abounds with repetitive sounds, some of which are related to pitch perception. It is still unknown how the auditory system, in processing these sounds, relates a physical stimulus and its percept. Since, in mammals, all auditory stimuli are conveyed into the nervous system through the auditory nerve (AN) fibers, a model should explain the perception of pitch as a function of this particular input. However, pitch perception is invariant to certain features of the physical stimulus. For example, a missing fundamental stimulus with resolved or unresolved harmonics, or a low and high-level amplitude stimulus with the same spectral content–these all give rise to the same percept of pitch. In contrast, the AN representations for these different stimuli are not invariant to these effects. In fact, due to saturation and non-linearity of both cochlear and inner hair cells responses, these differences are enhanced by the AN fibers. Thus there is a difficulty in explaining how pitch percept arises from the activity of the AN fibers.

We introduce a novel approach for extracting pitch cues from the AN population activity for a given arbitrary stimulus. The method is based on a technique known as sparse coding (SC). It is the representation of pitch cues by a few spatiotemporal atoms (templates) from among a large set of possible ones (a dictionary). The amount of activity of each atom is represented by a non-zero coefficient, analogous to an active neuron. Such a technique has been successfully applied to other modalities, particularly vision. The model is composed of a cochlear model, an SC processing unit, and a harmonic sieve. We show that the model copes with different pitch phenomena: extracting resolved and non-resolved harmonics, missing fundamental pitches, stimuli with both high and low amplitudes, iterated rippled noises, and recorded musical instruments.

19 באפריל 2017, 15:00

חדר 011, בניין כיתות-חשמל

סמינר אלקטרוניקה פיזיקאלית רנן נדלין כרמלי

30 במרץ 2017, 11:00

הפקולטה להנדסה ביניין כיתות חדר 011

סמינר אלקטרוניקה פיזיקאלית רנן נדלין כרמלי

You are invited to attend a lecture

Sub-Panel Sizing Optimization in Distributed Maximum Power Point (DMPPT) Photo-Voltaic (PV) Systems

By:

Renen Nadlin Carmeli

M.Sc student under supervision of Prof. Sigmond Singer and Dr. Yuval Beck

Abstract

With the use of photovoltaic (PV) systems becoming increasingly prevalent worldwide, the need for higher efficiency of the power harvesting process also rises. The converting ability of a single solar cell is limited, and is affected by changes of sun irradiation, shadows, temperature, humidity, etc. Currently, most PV systems are equipped with a Maximum Power Point Tracker (MPPT), designed to simulate working conditions for the PV system, when maximum available power is extracted from it.

The objective of this research is to examine the overall efficiency of distributed MPPT (DMPPT) PV systems, to map different topologies and scenarios, and to determine whether a single global optimal sub-panel size exists.

For the purpose of this research an algorithm was designed, which simulates different systems and scenarios, from a single PV cell topology to a full PV panel.

The results in all the tested scenarios showed that as the granularity of the DMPPT increases, a larger amount of power can be harvested. That, in spite of the fact that a dc/dc converter’s efficiency significantly diminishes as input power is reduced.

On Thursday, March 30, 2017, 11:00

Room 011, Kitot building

School of Mechanical Engineering Michael Lahutin

19 באפריל 2017, 14:00 - 15:00

בניין וולפסון 206

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School of Mechanical Engineering Michael Lahutin

School of Mechanical Engineering Seminar
Wednesday, April 19, 2017 at 14:00
Wolfson Building of Mechanical Engineering, Room 206

Active Flow Control of Wing-tip Flow Separation

Michael Lagutin

MSc Student of Prof. Avraham Seifert

School of Mechanical Engineering, Tel Aviv University, 69978 Tel Aviv, Israel

High-Lift devices, such as leading-edge slat, are commonly used in aerodynamics for increasing airfoil and wing performance at high incidence angles, mainly for takeoff and landing. However, due to complexity, weight, and cost of the deploying mechanism, the slat is not covering the full span of the wing, thus leaving the tip region “unprotected.” The slat termination creates slat-edge vortices that impinge upon the upper wing surface. The slat-edge-generated stream-wise vortices are negatively affecting the performance of the outer wing portion, resulting in local flow separations that reduce lift and significantly increase drag.

The current study deals with this problem, and was performed on an industry relevant geometry, in collaboration with Israel Aerospace Industries (IAI) and Airbus as part of the AFLONEXT EU FP7 project. The motivation of the work is to increase the robustness of the wingtip design at take-off conditions, while improving the aerodynamic efficiency at cruise conditions by closer to optimized design. The experimental model is a 3D high-lift wing configuration, which consists of swept-back (by 25°) wing with trailing edge flap fixed at 20°, leading edge slat and rounded wing tip. Active flow control (AFC) is used to delay the wingtip stall, thus improving the lift to drag ratio and allowing a steeper climb gradient. The AFC configuration was chosen based on previous studies and CFD results obtained by IAI. The work focused on steady suction AFC method, its effect was investigated through wind tunnel tests. Experiments consisted of pressure map acquiring, near wake 3D scans and a use of flow visualization techniques.

It was shown, that AFC application can delay stall, increase lift and reduce drag on the “unprotected” (by the slat) wing-tip region. The results were compared and mutually validated by CFD data obtained by IAI. It is expected that cruise optimized wingtip design will be able to provide an improvement in aerodynamic efficiency with a net benefit in fuel consumption and emissions up to 2%.

School of Mechanical Engineering Dr. Bat-El Pinchasik

07 ביוני 2017, 14:00 - 15:00

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School of Mechanical Engineering Dr. Bat-El Pinchasik

School of Mechanical Engineering Seminar
Wednesday, June 7, 2017 at 14:00
Wolfson Building of Mechanical Engineering, Room 206

A Lesson from Nature:

Underwater Reversible Adhesion using Air Capillary Bridges

Dr. Bat-El Pinchasik

Max Planck Institute for Polymer Research Mainz, Germany

Animals in nature, specifically insects, make extensive use of hydrophobic interactions for a wide variety of tasks: from gliding on the water surface through directional diving and even remaining dry underwater. Especially surprising is the ability of the leaf and ladybird beetles to walk underwater. That is, to adhere to submerged solid surfaces. By entrapping air in a hair-like hydrophobic structure they form air capillary bridges which are used to reversibly adhere and perform locomotion underwater. In order to develop a physical model to describe this mechanism, the different contributing parameters should be first identified and characterized: from structural design of the beetle’s adhesive pad to the physio-chemical properties of its cuticle. Based on numerical simulations it is possible to establish guiding principles for the design of synthetic structures for strong underwater reversible adhesion. These findings are not only important for understanding hydrophobic forces in nature but also for developing bio-inspired materials and systems for propulsion, actuation and locomotion on the micro scale. These principles can be applied for the reduction of friction in underwater transportation, control of the floatation and diving of aquatic vehicles and reduction of underwater noise.

סמינר מחילקתי

More for Less: Adaptive Labeling Payment for Online Labor Markets”

Dr. Tomer Geva – faculty member, Coller School of Management, Tel Aviv University

Abstract:

Predictive modeling has emerged as integral to the efficient operations and competitive strategies of firms across industries. Because many important predictive tasks require human intelligence to label training instances, online crowdsourcing markets have become a promising platform for large-scale labeling. However, prior research found major quality issues in such markets. In particular, very different tradeoffs arise between payment offered to labelers and the quality of labeling under different settings, and, more broadly, work quality may change over time and with changes in the competitive market settings. Further, determining the effect of labeling quality on the expected improvement in predictive performance is also challenging. Therefore, effective means for dealing with these challenges are essential for a growing reliance on these markets for predictive modelling. In this paper, we propose the new data science problem of Adaptive Labeling Payment (ALP): how to determine and continuously adapt the payment offered to crowd workers, before they undertake a labeling task, so as to produce a given predictive performance cost-effectively. We develop an ALP framework and derive a novel ALP method, which we evaluate extensively over a wide variety of market conditions. We find that our ALP method yields substantial cost savings and robust performance that can be relied on by businesses over a wide variety of settings.

(Joint work with Harel Lustiger and Maytal Saar-Tsechansky)

ההרצאה תתקיים ביום שלישי, 28.03.17 בשעה 14:00 , בחדר 206, בניין וולפסון, הפקולטה להנדסה, אוניברסיטת תל-אביב.

28 במרץ 2017, 14:00

חדר 206 בניין וולפסון

סמינר מחלקתי - אלקטרוניקה פיזיקאלת עמיחי מאירי

30 במרץ 2017, 15:00

אוניברסיטת תל אביב פקולטה להנדסה ביניין כיתות חדר 011

סמינר מחלקתי - אלקטרוניקה פיזיקאלת עמיחי מאירי

You are invited to attend a lecture

Enhancing optical nanoscopy by point-spread-function
spatial modulation

By:

Amihai Meiri

Faculty of Engineering, Bar Ilan University.

Abstract

An optical microscope has a fundamental limit of resolution: the diffraction limit, approximately 200nm for visible light. Nanoscopy methods such as STED and PALM/STORM were developed to overcome this limitation, and are capable of optical imaging with a resolution of 20– 50nm. Localization microscopy methods (PALM/STORM and single particle tracking) rely on the ability to precisely find the position of a single point emitter, where the resolution depends directly on the precision of localization.
In this talk I will describe how spatial modulation of the signal coming from a microscope can improve the capability to localize single emitters, in particular for particle tracking applications using scattering objects such as metal nanoparticles. In addition, I will show how this technique may be applicable to incoherent point sources such as fluorescent probes. This solution allows for faster, higher resolution imaging with relatively simple and low cost means, and can be used with any optical microscope.

On Thursday, March 30, 2017, 15:00
Room 011, Kitot building

School of Mechanical Engineering Inna Horovitz

24 באפריל 2017, 14:00 - 15:00

בניין וולפסון חדר 206

School of Mechanical Engineering Inna Horovitz

School of Mechanical Engineering Seminar
Monday, April 24, 2017 at 14:00
Wolfson Building of Mechanical Engineering, Room 206

Application of nano-structured solar photocatalytic membrane reactor for water treatment

Inna Horovitz

PhD Student of Prof. Hadas Mamane and Prof. Dror Avisar

Microfiltration (MF, with pores in the 0.1-10 μm range) systems offer quick and selective separation of suspended particles, larger pathogenic micro-organisms while operating at low transmembrane pressure. However, a number of contaminants, including micro-pollutants and viruses, can only be poorly removed from water by MF alone. Combining membrane filtration and advanced oxidation processes (AOP) as photocatalysis can potentially provide high water quality in a single step. Photocatalysis, which is classified as a heterogeneous AOP, is a process where a semiconductor (catalyst) is activated with sunlight irradiation following formation of highly oxidative species on the catalytic surface. A hybrid photocatalytic membrane reactor (PMR) can address multiple functions besides traditional physical separation as degradation of organic pollutants, disinfection and self-antibiofouling action. In this seminar, the efficiency of N-doped TiO₂-coated Al₂O₃MF membranes for water treatment will be presented. The photocatalytic activity (PCA) and the impact of physical and operational parameters such as operation mode (surface vs. in-pore PCA), wavelength dependence and flow rate of the suggested PMR will be presented by following the degradation of environmentally persistent pharmaceutical carbamazepine. Removal of MS2 bacteriophage, a surrogate for pathogenic waterborne viruses, by the PMR will be presented as a study case for disinfection efficiency. Virus removal in different water qualities will be addressed and correlated to the physico-chemical properties of the virus and the membrane.

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