College of Engineering
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The College of Engineering at Montana State University will serve the State of Montana and the nation by fostering lifelong learning, integrating learning and discovery, developing and sharing technical expertise, and empowering students to be tomorrow's leaders.
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Item Real-Time Digitization of Metabolomics Patterns from a Living System Using Mass Spectrometry(2014-10) Heinemann, Joshua; Noon, Brigit; Mohigmi, Mohammad J.; Mazurie, Aurélien J.; Dickensheets, David L.; Bothner, BrianThe real-time quantification of changes in intracellular metabolic activities has the potential to vastly improve upon traditional transcriptomics and metabolomics assays for the prediction of current and future cellular phenotypes. This is in part because intracellular processes reveal themselves as specific temporal patterns of variation in metabolite abundance that can be detected with existing signal processing algorithms. Although metabolite abundance levels can be quantified by mass spectrometry (MS), large-scale real-time monitoring of metabolite abundance has yet to be realized because of technological limitations for fast extraction of metabolites from cells and biological fluids. To address this issue, we have designed a microfluidic-based inline small molecule extraction system, which allows for continuous metabolomic analysis of living systems using MS. The system requires minimal supervision, and has been successful at real-time monitoring of bacteria and blood. Feature-based pattern analysis of Escherichia coli growth and stress revealed cyclic patterns and forecastable metabolic trajectories. Using these trajectories, future phenotypes could be inferred as they exhibit predictable transitions in both growth and stress related changes. Herein, we describe an interface for tracking metabolic changes directly from blood or cell suspension in real-time.Item Development of two-phase flow regime specific pressure drop models for proton exchange membrane fuel cells(2015-01) Anderson, Ryan; Eggleton, Erica; Zhang, LifengWater is an inevitable byproduct in proton exchange membrane fuel cells that can lead to complex two-phase flow throughout the cell's components, including the flow field channels utilized for gas delivery. A modified Lockhart–Martinelli (LM) approach based on unique water introduction through the gas diffusion layer is used here to predict the gas–liquid pressure drop in these channels by modifying the Chisholm parameter C. This paper exclusively uses experimental data of two-phase flow multipliers from four sources in the literature, all of which are obtained from active fuel cell operation. C does not appear to change strongly as a function of temperature, relative humidity, or air stoichiometry, but does vary significantly with the current density. This is especially true at low current densities (<500 mA cm−2). To capture this behavior, C is defined as a flow regime dependent parameter based on a flow regime map from the active fuel cell data. In addition to the traditionally used slug, film, and single-phase regimes, an ‘accumulating’ flow regime is proposed to capture the behavior of C and two-phase flow multipliers at low current densities. The proposed accumulating flow regime is consistent with visual observation reported in the literature. In addition, the developed LM approach can be employed to optimize fuel cell flow field design and operation.Item Selective Activation of Intrinsic Cohesive Elements.(2014-12) Kyeongsik, W.; Peterson, William Matthew; Cairns, Douglas S.In this paper, a selective activation strategy is studied in order to alleviate the issue of added compliance in the intrinsic cohesive zone model applied to arbitrary crack propagation. This strategy proceeds by first inserting cohesive elements between bulk elements and subsequently tying the duplicated nodes across the interface using controllable multi-point constraints before the analysis begins. Then, during the analysis, a part of the multi-point constraints are selectively released, thereby reactivating the corresponding cohesive elements and allowing cracks to initiate and propagate along the bulk element boundaries. The strategy is implemented in Abaqus/Standard using a user-defined multi-point constraint subroutine. Analysis results indicate that the strategy significantly alleviates the added compliance problem and reduces the computation time.