19 Jul 2024

Permafrost and Groundwater Characterization at the Proximity of the Landfill, Fort Wainwright, Alaska

Abstract: This report summarizes a site investigation at the vicinity of the landfill, a discontinuous permafrost site, at Fort Wainwright, Alaska. The objective of this effort was to characterize the permafrost extent and groundwater flow at the study area, and to compare newly collected subsurface characteristics with historical datasets. The main tasks for this effort included lidar and remote sensing analyses, geophysical investigations, a tracer dye study, contaminant trend analysis, and installation of soil temperature sensors. Findings included changes in stream channels and watershed boundaries, and elevation losses (0.2 m to 1 m) east and northeast of the landfill. From frost probe measurements, we found that depths to permafrost were up to 1.5 m deeper in 2021 than in 2010 where the difference in depth ranged from 20% to more than 350%. Furthermore, we detected a reduction in lateral permafrost extent from geophysical datasets. The groundwater flow direction, as detected through the dye study, was south to southwest. Dye was detected up to 2,300 m from the injection point. Groundwater travel times, as calculated from the dye study, varied greatly. For upcoming historical comparisons, it is recommended that data collections are performed using similar methods as described in this study.

28 Sep 2022

A Fuzzy Epigenetic Model for Representing Degradation in Engineered Systems

Abstract: Degradation processes are implicated in a large number of system failures, and are crucial to understanding issues related to reliability and safety. Systems typically degrade in response to stressors, such as physical or chemical environmental conditions, which can vary widely for identical units that are deployed in different places or for different uses. This situational variance makes it difficult to develop accurate physics-based or data-driven models to assess and predict the system health status of individual components. To address this issue, we propose a fuzzy set model for representing degradation in engineered systems that is based on a bioinspired concept from the field of epigenetics. Epigenetics is concerned with the regulation of gene expression resulting from environmental or other factors, such as toxicants or diet. One of the most studied epigenetic processes is methylation, which involves the attachment of methyl groups to genomic regulatory regions. Methylation of specific genes has been implicated in numerous chronic diseases, so provides an excellent analog to system degradation. We present a fuzzy set model for characterizing system degradation as a methylation process based on a set-theoretic representation for epigenetic modeling of engineered systems. This model allows us to capture the individual dynamic relationships among a system, environmental factors, and state of health .