School of Mechanical Engineering Ittai Shamir and Lior Shig
School of Mechanical Engineering Seminar
Wednesday, May 10, 2017 at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Investigating the morphometry of cortical layers
in the human brain
Ittai Shamir
MSc. Student of Professor Yaniv Assaf
and Professor Yair Shokef
Several Magnetic Resonance Imaging (MRI) approaches were demonstrated in recent years for visualization of the layer arrangement in the cortex either by using high resolution at high magnetic field or by investigating contrast mechanisms that separate the layers. Still, despite these technological achievements, accurate estimation of whole brain layer composition remains limited due to partial volume effects, since some of the layers are far beyond the image resolution.
In this study, we use a low resolution EPI inversion recovery (IR) scan protocol that provides fast acquisition (~12 minutes) and enables extraction of multiple T1 relaxation time components per voxel. These T1 components are assigned to brain tissue types and the assignment is utilized to extract the sub voxel composition of each of the cortical layers. Spatial analysis is conducted using our unique algorithm, based on sampling a network of spherical volumes dispersed throughout the entire cortical space.
Our suggested protocol offers a simple and accurate method for analysis of cortical layer composition, resolving partial volume effects. While direct visualization of the layers is not possible using our approach, it does offer a robust and powerful tool for investigating the layers and their role in cognition. Using this methodology, studies on the role of cortical thickness in brain function and behavior can be expanded to the cortical layer level, thus providing a new level of detail regarding cortical structure.
School of Mechanical Engineering Seminar
Wednesday, May 10, 2017 at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Active Flow Control of Submerged 3D Air Inlet
Lior Shig
MSc Student of Prof. Avi Seifert
Air ingesting propulsion systems that utilize the oxygen of the atmosphere for combustion require that the air transition with minimum pressure losses from the free stream to the engine's entrance. Small losses in internal flow given the large quantities of air required by jet engines cause serious decrease in the thrust and increase in fuel consumption.
Submerged inlets, are widely used in aircraft and cars as a low drag source of external flow for air conditioning, ventilation and cooling systems. The design criteria of these intakes was established during the 1940’s and 50’s. However due to boundary layer ingestion and distortion are not currently used for critical systems.
Flow analysis and boundary layer control methods were applied to a given submerged inlet design that is efficient from the external aerodynamic point of view. The approach for studying the effectiveness of active flow control methods on this kind of inlet was to significantly shorten the original inlet length, which caused internal flow separations and significant engine face distortions. For simplicity, and as an enabling step, low Reynolds number and low Mach number experiments were performed. The preliminary stages of this study included analysis of the baseline flow features of the chosen original inlet design and shortened version. Passive and active flow control techniques were applied to the short inlet in various locations in order to test the sensitivity of the flow to actuation and try to improve the Aerodynamic Interface Plane flow characteristics. Performance parameters such as volumetric flow rate, pressure recovery and flow distortion were defined and calculated in order to evaluate and quantify the level of success. For each of the applied techniques, the effects on the internal flow and integral parameters were measured and analyzed.
