Notes on Finite Element Discretization for a Model Convection-Diffusion Problem

We present recent finite element numerical results on a model convection-diffusion problem in the singular perturbed case when the convection term dominates the problem. We compare the standard Galerkin discretization using the linear element with a saddle point least square discretization that uses quadratic test functions, trying to control and explain the non-physical oscillations of the discrete solutions. We also relate the up-winding Petrov-Galerkin method and the stream-line diffusion discretization method, by emphasizing the resulting linear systems and by comparing appropriate error norms. Some results can be extended to the multidimensional case in order to come up with efficient approximations for more general singular perturbed problems, including convection dominated models.Comment: 24 pages, 12 figure

Integrating decision analysis, engineering and water quality modelling for remedial option evaluation of the 2200 level and Mount Sheer townsite at Britannia Mine

This case study presented a modified MAA approach that considers copper load reduction and cost to evaluate and select a preferred remedial option for the management of mine waste. A remedial option evaluation was undertaken to identify, design, cost and evaluate risk-based remedial options that could be employed to reduce copper loadings to Britannia Creek by >50% and address unacceptable aquatic risks at the 2200 Level of Britannia Mine. Previous investigations found the primary sources of copper were waste rock, highly leachable copper plant residuals and contaminated soils. Remedial approaches were screened for five Areas of Environmental Concern (AECs) using a modified Multiple Accounts Analysis approach with input from experienced professionals at technical workshops. Five remedial options were designed for the 2200 Level and two remedial options were developed for Mount Sheer using best management practices for control of metal leaching and acid rock drainage. Remedial options utilized passive approaches to maintain separation between clean water and waste materials at the remote unpowered site. Remedial options and detailed cost estimates were developed in consideration of the Overall Closure Plan Framework for the Britannia Mine Site. A water balance and water quality model was developed based on the Conceptual Site Model to quantitatively estimate copper load reduction to Britannia Creek for each remedial option. Input data for the model was obtained from public sources and historical studies documenting the extents of the AECs, geochemistry of waste materials, hydrology and hydrogeology. The model was used to predict water quality in Britannia Creek and estimate copper load reduction for each remedial option. Two options did not achieve the remedial goal of 50% copper load reduction and were abandoned. The other three options met the remedial goal with an estimated reduction of 65-69%. The preferred remedial option was selected after consideration of capital costs, long-term costs and estimated load reduction that is supported by a rapid, defensible and traceable evaluation process.Non UBCUnreviewedOthe

Predicting illegal income generation among homeless male and female young adults: Understanding strains and responses to strains

This study examined gender differences among homeless young adults\u27 engagement in illegal economic activity (i.e., panhandling, selling drugs, survival sex, gambling, theft). A purposive sample of 601 homeless young adults (ages 18–24) was recruited from three U.S. cities (Los Angeles, CA [n = 200], Austin, TX [n = 200], and Denver, CO [n = 201]) to participate in semi-structured interviews. General strain theory was used to identify predictors of illegal economic activity, including strains (childhood abuse, street victimization, length of homelessness, transience) and responses to strain (deviant peer associations, substance use, post-traumatic stress disorder, arrest history). The full hypothesized path models for males and females separately were tested using observed-variable path analysis. Among females, a greater variety of illegal income sources was reported by those who had experienced greater street victimization and who had used a greater number of substances in the past year. Among males, a greater variety of illegal income sources was reported by those who had more deviant peer associations, experienced greater street victimization, and used a greater number of substances in the past year. Findings have implications for research and preventive interventions to address engagement in illegal economic activity among male and female homeless young adults

Impact of climate change on fishes in complex Antarctic ecosystems

Antarctic marine ecosystems are increasingly threatened by climate change and are considered to be particularly sensitive because of the adaptation of most organisms to cold and stable environmental conditions. Fishes play a central role in the Antarctic marine food web and might be affected by climate change in different ways: (i) directly by increasing water temperatures, decreasing seawater salinity and/or increasing concentrations of CO2; (ii) indirectly by alterations in the food web, in particular by changes in prey composition, and (iii) by alterations and loss of habitat due to sea ice retreat and increased ice scouring on the sea floor. Based on new data and data collected from the literature, we analyzed the vulnerability of the fish community to these threats.The potential vulnerability and acting mechanisms differ among species, developmental stages and habitats. The icefishes (family Channichthyidae) are one group that are especially vulnerable to a changing South Polar Sea, as are the pelagic shoal fish species Pleuragramma antarcticum. Both will almost certainly be negatively affected by abiotic alterations and changes in food web structure associated with climate change, the latter additionally by habitat loss. The major bottleneck for the persistence of the majority of populations appears to be the survival of early developmental stages, which are apparently highly sensitive to many types of alterations. In the long term, if climate projections are realized, species loss seems inevitable: within the demersal fish community, the loss or decline of one species might be compensated by others, whereas the pelagic fish community in contrast is extremely poor in species and dominated by P. antarcticum. The loss of this key species could therefore have especially severe consequences for food web structure and the functioning of the entire ecosystem.Fil: Mintenbeck, Katja. Alfred Wegener Institute For Polar And Marine Research; AlemaniaFil: Barrera Oro, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Brey, Thomas. Alfred Wegener Institute For Polar And Marine Research; AlemaniaFil: Jacob, Ute. Universitat Hamburg; AlemaniaFil: Knust, Rainer. Alfred Wegener Institute For Polar And Marine Research; AlemaniaFil: Mark, Felix C.. Alfred Wegener Institute For Polar And Marine Research; AlemaniaFil: Moreira, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Strobel, Anneli. Alfred Wegener Institute For Polar And Marine Research; AlemaniaFil: Arntz, Wolf E.. Alfred Wegener Institute For Polar And Marine Research; Alemani