19 Jan 2021

Soo Locks upgrading park’s lock model displays

DETROIT- Soo Locks visitors will see more than $100,000 in improved lock model displays in the coming years thanks to local partner support and the U.S. Army Corps of Engineers’ Handshake Partnership Program. Currently, the park features two original 3-D models dating back to 1893 and 1912, showing locks built on the facility over 100 years ago. The models sit in concrete and glass cases with cracked panes and openings in the bases allowing air, moisture and insects to get inside. The oldest model was built to test the original Poe Lock plans in 1893 as evidenced by a photo discovered by Chief Park Ranger Michelle Briggs while working with historic photos. “I was doing some research when I found a photo dated March 1893 of the workmen posed with the model of the original Poe Lock, which I recognized from the park,” Briggs said. “I am sure this model was finished shortly after the picture was taken since one of the workmen is still holding a paint brush.”

11 Aug 2020

PUBLICATION NOTICE: The Urban Ground-to-Ground Radio-Frequency Channel: Measurement and Modeling in the Ultrahigh Frequency Band

ABSTRACT:  Ground-to-ground radio communication and sensing within the urban environment is challenging because line of sight between transmitter and receiver is rarely available. Therefore, radio links are often critically reliant on reflection and scattering from built structures. Little is known about the scattering strength of different buildings or whether such differences are important to the urban ground-to-ground channel. We tested the hypotheses that (1) diffuse scattering from built structures significantly impacts the urban channel and (2) scattering strength of urban structures varies with surface roughness and materials.  We tested these hypotheses by measuring urban channels in Concord, New Hampshire, and Boston, Massachusetts, and via channel-modeling efforts with three-dimensional representations of the urban environment. Direct comparison between measured and modeled channels suggest that both of these hypotheses are true. Further, it appears that ray-tracing approaches underestimate the complexity of urban channels because these approaches lack the physical processes to correctly assess the power incident on and scattered from built structures. We developed a radio-geospatial model that better accounts for incident power on both directly visible and occluded buildings and show that our model predictions com-pare more favorably with measured channels than those channels predicted via typical ray-tracing approaches.