הפקולטה להנדסה ע"ש איבי ואלדר פליישמן

Material Sciences and Engineering: Departmental Seminar

Mr. Ilya Svetlitzky

The Racah Institute of Physics, The Hebrew University of Jerusalem

Classical shear cracks drive the onset of frictional motion

06 באפריל 2016, 16:00

Room 103, Engineering Class (Kitot) Building

Classical shear cracks drive the onset of frictional motion

Material Sciences and Engineering: Departmental Seminar

Single walled carbon nanotubes as optical sensors at the nanoscale

Dr. Gili Bisker

Department of Chemical Engineering, Massachusetts Institute of Technology

30 במרץ 2016, 16:00

Room 103, Engineering Class (Kitot) Building

Single walled carbon nanotubes as optical sensors at the nanoscale

Material Sciences and Engineering: Departmental Seminar

Dr. Rami Cohen

Department of Materials Engineering, Elbit systems, Electrooptics, ELOP

Challenges & Research topics
at Materials engineering

16 במרץ 2016, 16:00

Room 103, Engineering Class (Kitot) Building

Challenges & Research Topics in Materials Engineering

סמינר מחלקתי - דן ימין

Optimal dosing of rotavirus vaccination in Japan

08 במרץ 2016, 14:00

חדר 206 בניין וולפסון

Rotavirus, the primary cause of gastroenteritis in children, poses a significant health and economic burden. A highly effective three-dose pentavalent vaccine course is widely used as part of infant immunization schedule worldwide, and has been licensed in Japan since 2011. As rotavirus is contagious, each vaccinated individual diminishes transmission within the population. Therefore, providing complete protection to all individuals might not be essential to contain the disease. To evaluate the number of vaccine doses sufficient to curtail transmission in Japan, we developed an age-structured mathematical model of rotavirus transmission. We conducted a survey study with 3,126 participants to quantify the contact mixing patterns of the Japanese population, and fitted model parameters to rotavirus vaccine clinical trial data as well as nine years of rotavirus incidence in Japan. Counterintuitively, model simulations under alternate dosing strategies suggested that, compared to no vaccination, a single-dose-regimen could be counterproductive in the first three years following implementation. In contrast, the first two doses were found to be responsible for 97% of the reduction in severe rotavirus infection, while the third accounted for only the remaining 3%. Thus, despite manufacturer and the World Health Organization recommendations, as a consequence of indirect protection, the necessity of the third dose should be revisited in Japan.

ההרצאה תתקיים ביום שלישי 15.3.16, בשעה 14:00 , בחדר 206, בניין וולפסון, הפקולטה להנדסה, אוניברסיטת תל-אביב.

סמינר מחלקתי Erez Benjamin

23 במרץ 2016, 15:00

וולפסון 206

School of Mechanical Engineering Seminar
Wednesday, March 23, 2016 at 15:00
Wolfson Building of Mechanical Engineering, Room 206

Bistable Force\Acceleration Sensor Based on Critical Voltage Monitoring

Erez Benjamin

M.Sc. Student of Prof. Krylov

Micro-electromechanical systems (MEMS) are embedded devices or systems composed of micro machined structures. Micro accelerometers are among the most promising and intensively researched applications of the MEMS technology. In this work we report on fabrication and experimental demonstration of force\acceleration sensing in a fully compliant contactless bistable structure, electrostatically actuated by a single parallel-plate transducer. The operational principle of the sensor is based on the monitoring of the stability boundaries of the device. Previous work found the stability properties of the device to be sensitive to fabrication tolerances. In the present work, careful mapping of the design parameters was carried out, which reduced the sensitivity to fabrication tolerances and assured the bistablility in the device.

The acceleration is measured by tracking the critical voltage corresponding to the instability point, where the sensitivity is enhanced. The proof mass is suspended using initially curved flexible beams pulled by nonlinear electrostatic forces directed along the beams. In contrast to conventional electrostatic actuators, where the so-called pull-in instability is followed by the collapse of the device to the electrode, in our device steep increase in the suspension's stiffness and appearance of an additional stable configuration of the device after the pull-in prevents the contact and eliminates irreversible damage of the structure. The model of the device built using the Rayleigh-Ritz method, incorporates structural geometric nonlinearity of the suspensions and the intrinsic electrostatic nonlinearity. To account for the influence of three-dimensional fringing fields, the electrostatic force was calculated numerically using the IntelliSuite software package. Devices of several configurations were fabricated from a silicon on insulator (SOI) substrate using deep reactive ion etching (DRIE) process. The devices were operated in ambient air conditions, the motion was video recorded and the voltage–displacement dependence was built using image processing. First, the bistability of the device was demonstrated experimentally at zero acceleration. Experimental data were in a good agreement with the model predictions. Next, the influence of an external force\acceleration was emulated with an additional parallel plate transducer. The sensitivity of 0.173 V/g shown in the experiments was in a reasonable agreement with the value of 0.149 V/g predicted by the model.

Department of Materials Science and Engineering - Special Seminar

Electromechanical Properties of Multi-Layer Graphene Contacts

Dr. Elad Koren

IBM Research - Zurich

01 במרץ 2016, 12:00

Room 206, Wolfson Building of Mechanical Engineering

Department of Materials Science and Engineering - Special Seminar

Electromechanical Properties of Multi-Layer Graphene Contacts - Dr. Elad Koren

סמינר הנדסה ביו רפואית

Identification of pathological changes in normal-appearing white and gray matter of multiple sclerotic patients using a novel quantitative-MRI technique

28 בפברואר 2016, 14:00

הבניין הרב תחומי , חדר 315

EE Seminar: Group Symmetric Covariance Estimation and Detection

~~(The talk will be given in English)

Speaker: Dr. Ilya Soloveychik
School of Computer Science and Engineering, Hebrew University

Monday, February 29th, 2016
15:00 - 16:00
Room 011, Kitot Bldg., Faculty of Engineering

Group Symmetric Covariance Estimation and Detection

Abstract
We focus on the problem of Gaussian and robust covariance estimation under group symmetry constraints. We assume the true estimated matrix to commute with a finite unitary matrix group, which is referred to as the group symmetry. Examples of group symmetric structures include circulant, persymmetric, proper quaternion and many others. We develop the group symmetric versions of the sample covariance and Tyler's estimators and determine their performance benefits. In particular, the classical results claim that at least n = p and n = p+1 sample points in general position are necessary to ensure the existence and uniqueness of the sample covariance and Tyler's estimator respectively, where p is the ambient dimension. We significantly improve these requirements for both estimates and show that in many cases even 1 or 2 samples are enough to guarantee the existence and uniqueness regardless of p. We build a unified framework for group symmetric estimation and explain the nature and consequences of the underlying block-diagonalization phenomenon. In addition, we develop a group symmetric detection framework and investigate the gains it yields.

29 בפברואר 2016, 15:00

חדר 011, בניין כיתות-חשמל

EE Seminar: Practical Waveform and Receiver Considerations for Continuous-Wave Bistatic and Multistatic Radars

~~Speaker: Itzik Cohen,
M.Sc. student under the supervision of Prof. Nadav Levanon

Wednesday, February 24, 2016 at 15:00
Room 011, Kitot Bldg., Faculty of Engineering

Practical Waveform and Receiver Considerations for Continuous-Wave Bistatic and Multistatic Radars

Abstract

The prevailing waveforms in modern continuous wave (CW) bistatic and multistatic radars are signals-of-opportunity which rarely have good properties for optimal radar performance, whereas linear frequency modulation CW (LFM-CW), which is the most popular CW waveform for monostatic radar, loses some of its strengths in the bistatic and multistatic case. That opens the competition for other periodic waveforms.
In this talk, the advantages of bi-phase and 3-phase CW waveforms are described and demonstrated, through bistatic field trials. Among them are sidelobe-free range response, low Doppler recurrent lobes and relative ease of transmitter-receiver synchronization. Another important property of these families of periodic waveforms is the availability at all prime lengths, and good inter-signal separability (low cross-correlation and cross-ambiguity function), for the sake of multistatic scenes. Spectral efficiency (low out-of-band emission) is achieved either by a Gausian weighted sync (GWS) chip shape, with a penalty of varying amplitude, or by quadriphase continuous phase modulation. Also, some receiver considerations will be discussed.
Results from lab experiments and field trials will be presented.

24 בפברואר 2016, 15:00

חדר 011, בניין כיתות-חשמל

EE Seminar: Robust registration between high-field preoperative and low-field intraoperative brain MRI

~~Speaker: Ori Weber
M.Sc. student under the supervision of Prof. Nahum Kiryati

Wednesday, February 24th, 2016 at 15:30
Room 011, Kitot Bldg., Faculty of Engineering

Robust registration between high-field preoperative and low-field intraoperative brain MRI

Abstract

Preoperative high-resolution brain MRI is commonly used to produce high quality anatomical MRI as well as diffusion tensor imaging trachtography and functional MRI. While preoperative high-resolution MRI is very useful for lesion detection and surgery planning, it has only a limited validity as an anatomical reference for navigation during open brain surgery. When the skull is opened (craniotomy), at the beginning of surgery, cerebrospinal fluid leaks out, causing the brain to drift progressively with regard to the skull. As surgery progresses, local deformations caused by ongoing tissue resection further increase the discrepancy between preoperative MRI and the actual brain anatomy.

During the last decade, low-field (.15T) intraoperative MRI (iMRI) has been developed to provide updated MRI images during brain surgery, thereby providing real-time images of the brain for improved navigation. While low-field intraoperative MRI provides some degree of anatomical guidance during surgery, it cannot replicate the functionality, in terms of resolution, signal-to-noise, field-of-view and the ability of diagnostic systems to provide fMRI and DTI information. Therefore, the ability to quickly map information obtained from the preoperative images directly to the intraoperative environment, while taking into account brain-shift and tissue resection, would provide significant improvement in image quality, leading to higher accuracy of navigation during surgery.

This thesis proposes a robust, automatic and real-time framework of coupling high-field preoperative and low-field intraoperative MRI, and projecting preoperatively acquired fMRI and tractography maps during the ongoing surgery. In the proposed method, open brain surgery is analyzed as a succession of three consecutive phases: pre-craniotomy, post-craniotomy and post-resection. Each phase has a tailor-made pipeline which explicitly takes into account its respective challenge: the limited intraoperative MRI field-of-view, the brain-shift effect, and the extracted brain tissues following resection. Quantitative validation results are presented on a set of 20 real interventional cases.

24 בפברואר 2016, 15:30

חדר 011, בניין כיתות-חשמל

עמודים