Small-scale physical modelling of scour at bridge piers with light-weight sediments

This study entailed physical model testing to support the design of marine facilities associated with a proposed 36 km long causeway, which is under construction in Kuwait Bay. The marine facilities include 1050 bridge piers, to be built in varying conditions in terms of water depth, soil conditions, current and wave conditions. Seabed levels vary from intertidal to approximately -12 m MSL and three different types of seabed material were observed: cap-rock underlain by sand, silty sand and silty clay. Light-weight sediment physical models with scales 1:20 and 1:37 were used to assess scour potential due to waves and currents at the base of the bridge piers and to guide the design of scour protection (rock armouring of the seabed). The PVC light-weight particles used to model the prototype silty sand had a density of approximately 1200 kg/m3 and a median diameter (d50) of 0.25 mm. Quantitative assessments of the seabed evolution were made with advanced photo-scan techniques. The model results provide insight to the evolution of scour over time and equilibrium scour hole dimensions, which were compared to predictions using empirical formulae. The similitude laws that apply for this type of model and observed model effects are also discussed

Characterization of Antibiotic Resistant Genes in Two Unique City Sewer Systems

University of Minnesota M.S. thesis. 2020. Major: Water Resources Science. Advisor: Chan Lan Chun. 1 computer file (PDF); 65 pages.Sewer systems are known as point sources for the release of antibiotic resistance into the environment. Antibiotic resistance genes (ARGs) provide bacteria the ability to fight antibiotics and are viewed as emerging contaminants in environmental waterways. To minimize the spread of ARGs to the environment, this study assessed the prevalence of ARGs in upstream sewer systems that feed into wastewater treatment plants (WWTPs) so that source control strategies can be developed to mitigate the spread of antibiotic resistance. Wastewaters were examined from two unique city sewer systems containing three source types: hospital, residential, and industrial. Twenty-nine ARGs, 3 integron-intergrases, and 4 metal resistance genes were quantified using conventional and microfluidic polymerase chain reactions. Bacterial community compositions were characterized using high-throughput 16S rRNA amplicon sequencing. We found the levels of ARGs and bacterial community compositions to be dependent on the source of wastewater, the city, and the season. The abundance of ARGs in hospital wastewater were relatively constant and associated with clinically relevant antibiotics. ARG abundance in residential wastewater showed seasonal variations with high levels in winter associated with outpatient antibiotics. High levels of integron-integrase genes, a proxy for horizontal gene transfer and anthropogenic impacts, were also observed in residential wastewaters. Based on these findings we suggest satellite treatment of ARGs at hospital and residential sources to reduce their loading to WWTPs and their inevitable release to the environment

ATX Power Supply

ATX Power Supply is sponsored by Plexus with the goal of designing and prototyping an open-source, high-powered ATX power supply. Our first prototype is split up into 3 printed circuit boards (PCBs): EMI filtering & PFC, LLC Converter, and DC-DC Converter. These PCBs are made larger than the ATX form factor to provide ample space for the testing and debug phase

Flood risk analysis for the Belgian-Dutch coast

The coastal lowlands of the Belgian region Flanders and of the Dutch region Zeeuws-Vlaanderen constitute a single cross-border flood unit. If a dike breaches in the Dutch part of this flood unit, the water might well flow into Belgium and vice versa. In order to achieve common approaches, a cross-border project, including some form of transnational co-operation with the responsible local authorities like the "Zeeuws-Vlaanderen Water Board", becomes necessary. Within the INTERREG IIIB project COMRISK and under the auspices of the North Sea Coastal Management Group, an international platform to implement such a cross-border pilot study has now been set up.status: publishe