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Part of Blue and Gold Weekend, The 11th Annual Drag Show, sponsored by the Center for Women, Gender, & Sexuality and the Student Activities, Involvement, & Leadership (SAIL) Office, is returning Thursday, Oct. 5! With returning hosts Complete Destruction and Jacqueline DiMera and special guests Adriana, Dahlia Strack, Throb Zombie, and Severity Stone. Don't miss out! To guarantee a seat, sign up online!

The Marketplace

Fall 2023 Final Exams end for the First 5-week session MLT-MLS Program classes.

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Topic: Mitigating Interferer Motion with Universal Adaptive Beamformers Location: Lester W. Cory Conference Room, Science & Engineering Building (SENG), Room 213A Zoom Conference Link: https://umassd.zoom.us/j/92380705367 Meeting ID: 923 8070 5367 Passcode: 539575 Abstract: A signal received by a passive sonar may contain the desired signal, background noise, and moving or nonmoving interferers simultaneously. The beamformer processes observed narrowband signals to implement a spatial filter by selecting the desired signal from a specific location while eliminating loud interference and noise from other locations. One of the most common adaptive beamformers is the minimum variance distortionless response (MVDR) beamformer. The MVDR beamformer minimizes the output power of the array subject to a unity gain constraint in the direction of the desired signal. The MVDR beamformer obtains a minimized output power by placing sharp notches in the location of the interferers. MVDR is an optimal beamformer when a nonmoving interferer is present. However, close range, fast interferers move with a high bearing rate, transiting resolution cells faster and challenging MVDR's ability to place accurate notches in the actual direction of the interferer. Consequently, the MVDR notch location will always slightly lag the interferer's actual location, and the MVDR beamformer's ability to suppress the interferer degrades. Applying a flatter and broader notch near the interferer location is a more effective approach to dealing with the interferer motion. Many proposed notch widening approaches attenuate the interferers by placing a fixed large notch in the direction of the interferer. Choosing a larger notch width is a conservative approach to attenuate interferers but wastes degrees of freedom and reduces the white noise gain. A universal beamformer can be used to balance the trade-off between interferer suppression and white noise attenuation by saving degrees of freedom even in dynamic environments. The universal beamformer converges to the performance of the best beamformer in a set by choosing the blend weights so that the regret goes to zero asymptotically. This work will investigate the universal version of double zero, the covariance matrix tapers, and spatial subband processing to expand the width of the notch with fewer degrees of freedom and analyze their respective performance in interferer suppression and white noise gain. Advisor(s): Dr. John R. Buck, Chancellor Professor, Department of Electrical & Computer Engineering, UMASS Dartmouth Committee Members: Dr. David A. Brown, Professor, Department of Electrical & Computer Engineering, UMASS Dartmouth; Dr. Paul J. Gendron, Associate Professor, Department of Electrical & Computer Engineering, UMASS Dartmouth; Dr. Kay L. Gemba, Professor, Naval Postgraduate School NOTE: All ECE Graduate Students are ENCOURAGED to attend. All interested parties are invited to attend. Open to the public. *For further information, please contact Dr. John R. Buck at 508.999.9237 or via email at jbuck@umassd.edu.

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Mechanical Engineering (MNE) SEMINAR DATE: October 6, 2023 TIME: 2:00 p.m. - 3:00 p.m. ZOOM: https://umassd.zoom.us/j/91640406955?pwd=eklBZWVDOXVDa2VwUFMra1kwNWhjdz09 (Passcode: 500) SPEAKER: Dr. Wen Wu, Assistant Professor Mechanical Engineering, General Engineering, University of Mississippi TOPIC: Roughness Effects in Non-Equilibrium Turbulent Flows ABSTRACT: Extensive studies have been performed in the realm of surface roughness in the areas of fluid dynamics, marine science, biomedical engineering, etc. The core of existing research is parameterizing the effects of roughness by an analogy to the smooth-wall logarithmic profile. Deviations from the canonical turbulent flow, however, challenge the validity of the law of the wall, thus imposing uncertainty in utilizing the roughness corrections developed for canonical turbulent boundary layers (TBL). In this talk, findings from several numerical investigations of roughness effects in non-equilibrium turbulent flows are discussed. A) Despite that roughness is often considered a mixing enhancer at the wall, it promotes the separation of TBL induced by an adverse pressure gradient rather than delaying it. B) DNS of channel flow subjected to spanwise rotation was performed, comparing cases with smooth and rough walls. The destabilizing effect of roughness counteracts the stabilizing effect of rotation and prevents flow from reaching a quasi-laminar state. The wake field, i.e., the spatial variation of the averaged quantities around the roughness elements, affects the shear stress budget most significantly. C) DNS of a pulsatile channel flow over roughness further highlights the critical role of the local flow around roughness elements in modifying the near-wall turbulence. BIO: Dr. Wen Wu is an Assistant Professor at the University of Mississippi (UM) since 2020. He completed his Ph.D. degree at Queen's University, Canada, and conducted his postdoctoral research at Johns Hopkins University. He also served as a Visiting Assistant Professor at the Center for Turbulence Research at Stanford during the summer of 2022 and 2023. Dr. Wu combines high-fidelity simulations and theoretical analysis for his research, with an emphasis on the multiscale and non-equilibrium aspects of turbulence. His recent research has focused on vortex-dominated flows, flow separation, and turbulence-surface structure interactions. For more information please contact Dr. Hangjian Ling, MNE Seminar Coordinator (hling1@umassd.edu). All are welcome. Students taking MNE-500 are REQUIRED to attend! All other MNE students (BS and MS) are encouraged to attend. EAS students are also encouraged to attend.

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Indigenous Peoples Day, no classes today.

UMass Dartmouth

Fall 2023 Second 5-week session MLT-MLS Program classes begin.

Online