Upcoming Doctoral Defense Announcements

Notice of every doctoral final defense will be publicized by the office of graduate studies at least one week prior to the examination. Details of upcoming defenses are listed below.

Majid S. Mohamod


DATE: Thursday, July 16, 2020

TIME: 11:00 AM

LOCATION: Join Zoom meeting https://umsystem.zoom.us/j/94017547409

ADVISOR: Dr. Katherine Grote



All around the world, the demand for water is increasing, especially in arid and semi-arid regions, including Iraq which subject to continuous desertification that is worsening, more importantly the Jezira region in northwestern Iraq. Thus, it’s crucial to have a better strategy for water management. One of these strategies is to promote groundwater recharge for restoring the aquifer depletion. One of the studies was presented in this research is about delineate favorable zone for groundwater recharge by overlaying thematic layers of soil type, lineament feature density, stream buffering distance, depth to groundwater, the annual flow in subbasin, stream density, and the geology of the study area. All have integrated by GIS tools which conclude that 11% of the study area considered as excellent zones for groundwater recharge. The successful groundwater recharge is controlled by several factors such as obtain the annual water budge in the region, moreover, precipitation is one of those potential factors contribute in water budget in many watersheds specially in arid and semi-arid regions. The ground observations are limited by sparse population which tends to be less in arid and semi-arid regions. Therefore, satellite-based precipitation has selected as an alternative to the ground measurement of rainfall. However, there is still significant uncertainty about the accuracy of these data. Therefore, seven precipitation estimates have tested against rain gauges in Orange County and Los Angeles County, California, which classify by semi-arid climate region. The satellite estimates are Global Precipitation Measurement (GPM), Multi-satellite Precipitation Analysis (TRMM 3B42), Global Satellite Mapping of Precipitation (GsMaP MVK), Climate Forecast System Reanalysis (CFSR), and Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN, PERSIANN-CCS and PERSIANN-CDR). Results indicated that TRMM was able to capture rainfall events accurately. In order to establish a water management strategy in Jezira region, annual water budget should be known, which could be measure through observational discharge station. Unfortunately, only few months of discharge was measured manually in the north Jezira, which Hatra subwatershed. Accordingly, we had to rely on an alternative method such as computer modeling. By reviewing previous work about hydrological model, The Soil and Water Assessment Tool (SWAT) was great candidate to overcome the problem. Satellite-based rainfall data were inputted into the SWAT model: TRMM 3B42 v07, PERSSIAN-CDR, and CFSR. The observational data of stream discharge was used to calibrate and validate the simulated results. The hydrological parameters which was extracted from the model could be regionalized to ungauged Jezria watersheds.

Yasser Darwish


DATE: Thursday, July 16, 2020

TIME: 3:00 PM

LOCATION: Join Zoom meeting https://umsystem.zoom.us/j/92453288095

ADVISOR: Dr. Mohamed ElGawady



Metamaterial systems with negative stiffness behavior became a point of interest in many energy dissipation applications due to their ability to dissipate high levels of energy. Negative stiffness metamaterial elements can dissipate energy through non-linear elastic behavior when transferred from one stable mode of buckling to another. Therefore, such elements have the capabilities to dissipate energy under repetitive and re-occurring loading. Such unique properties qualify the metamaterial systems as a perfect candidate for structural applications such as impact protection of infrastructure against collision. This research provides an innovative metamaterial shell structure that can exhibit negative stiffness behavior by deforming from one shape to another. The developed metamaterial shells have the potential to be used in different infrastructure applications that requires high levels of force thresholds and energy dissipation. The metamaterial shells were manufactured using 3D printing selective laser sintering (SLS). The shells were investigated under impact and quasi-static loading. Different profiles and configurations were investigated experimentally and numerically to optimize the amount of energy dissipated as well as the force threshold of the system to be adequate for infrastructure applications. Three-dimensional finite element models (FEMs) were also developed to address the instabilities occurred in the metamaterial elements and predict the force thresholds and energy dissipation levels. The FEMs were extended to investigate the effect of different parameters such as boundary condition and apex height-to-shell thickness ratio on the behavior of metamaterial elements. Results indicated that the developed metamaterial shells can dissipate up to 70% of the input energy, and achieve high force thresholds appropriate for infrastructure applications.