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Lipid Bilayer Nanoparticle Poration Most of the recent research on the cytotoxicity of nanomaterials has focused on hydrophilic nanomaterials because of their good dispersion in water. Much less research has been done on hydrophobic nanomaterials. We have here investigated the effect of semi-hydrophobic nanoparticles (NPs) on the dynamics and morphology of model cell membranes. We have found that carboxyl functionalized polystyrene nanoparticles can induce the formation of microscaled pores on neutral supported Egg PC lipid bilayer at the ionic strength range similar to that in the human body with a strong dependence on salt type and concentration. The hydrophobic interaction between the NP surface and lipid bilayer is accounted for by the induced line tension in the lipid bilayer; when the tension exceeds a critical value, pores are formed and grow rapidly with dependence on salt type and concentration. The Hofmeister series classifies ion in order of their effects upon the solubility of proteins. The anion Hofmeister trend holds for the model cell membrane system. Department of Chemical and Biomolecular Engineering |
Mobile Interface for the NDmesh Wireless Video Surveillance Network Description coming soon. Department of Computer Science and Engineering |
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Series Electric Hybrid Vehicle Description coming soon. Department of Electrical Engineering |
Investigation of (Gas) Turbine Rim Seal Temperatures Ingestion of core flow into the rim cavities of turbine stages is a significant problem in the turbomachinery industry. Hot gas seeping into these spaces between rotor and stator can have disastrous effects on the lifespan of the high speed rotating metal parts. It is believed that the primary cause of ingestion is the high rotational speed of the rotor sucking cavity air outward along the rotor into the gaspath, causing gaspath air to seep down the stator into the cavity. To prevent ingestion colder air is pumped from within to purge the cavity. This purge flow is leaked from the compressor in most applications, in exchange for an efficiency penalty. The balance between maximizing efficiency and protecting the rim cavities from ingestion is of great concern, especially in aircraft engine applications. Turbomachinery research at Notre Dame is presently underway on behalf of several aerospace companies using the single stage turbine rig at White Field. The rig uses atmospheric air (in absence of compressor bleeds) of variable temperature and flow rate to purge the rim cavity. Additionally, air of variable temperature is circulated within a cooling groove behind the stator. To complement the experimental work a computational model of the turbine rig's rim cavity is developed using COMSOL Multiphysics. Complicated numerical models play a vital role in the analysis of this problem both in industry and academia, but can take enormous amounts of time and effort to build and tune. For the purposes of this research, a simplified two-dimensional model is developed to gain a global, qualitative understanding of the effects of varying the problem's chief parameters on the heat transfer within the stator. Department of Aerospace and Mechanical Engineering |
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COMPARING THE EFFECTS OF PROTECTIVE PLATE SHAPE ON LEG INJURIES DURING FINITE ELEMENT BLAST SIMULATIONS WITH THE HYBRID III ATD This thesis explores leg injuries caused by blasts located underneath military vehicles and compares the effectiveness of different protective panel shapes in simulated blast environments. Four panels with shapes determined by different optimization techniques are affixed to a finite element model of a simplified vehicle. The control shape is flat, and the other three shapes come from Displacement Basis, Gaussian, and Hybrid Cellular Automata optimization algorithms. A model of an Anthropomorphic Test Device is imported into the set-up and arranged into a typical seated position. The ConWep function in LS-PrePost is applied to the bottom surface of the plates to represent a typical road mine. LS-DYNA mathematically calculates the loads on the surface using a loading function that does not incorporate the effects of the surroundings. The original designers of the simplified vehicle and plate model (Williams et al., 2003) verified the accuracy and applicability of the ConWep design to represent a physical model. The analysis focuses on leg injuries. Leg injuries are some of the most common and harmful injuries associated with blasts. Loading on the tibia and femur are calculated using LS-PrePost and compared to critical limit standards to estimate the possibility and severity of injury. The research suggests that the Displacement Basis plate offers the most protection of the four. However, all of the three modified plates improve upon the performance of the flat plate. The main variable that leads to the success of the Displacement Basis plate is the minimal distance the plate penetrates into the vehicle cabin. It retains its parabolic shape and does not snap through to enter the cabin. Thus, it does not make contact with the feet of the occupant. The limitations of this research stem from the inability of ConWep to account for the compounding effects of air and soil. Both can exacerbate the severity of injuries by creating a pressure wave and redirecting blast energy, respectively. However, this drawback can be accounted for by increasing the mass of the explosive material during simulations. Department of Aerospace and Mechanical Engineering |
Dynamic Wireless Spectrum Access Dynamic spectrum access requires sensing algorithms that allow secondary users with cognitive radio capabilities to communicate over a channel when no primary user is transmitting. These algorithms currently assume primary users' transmissions fit certain probabilistic models. I am collecting and analyzing usage data from wireless communication channels in order to develop an empirical model of a primary channel user's behavior with which this assumption can be tested. I am focusing on public safety communications channels because they include mobile transmitters with unpredictable usage patterns. The model developed will therefore be more generally applicable than one developed for TV white spaces, for example. Department of Electrical Engineering |
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GPU Acceleration of Protein Simulations Description coming soon. Department of Computer Science Engineering |
The Effects of Hurricanes on Coastal Construction Description coming soon. Department of Civil Engineering and Geological Sciences |
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Development of a Laser-Based Manufacturing Approach for Biometric Polymer Scaffolds Description coming soon. Department of Aerospace and Mechanical Engineering |
Characterization and Verification of Nonlinear Foam Material Properties under Dynamic Loading Description coming soon. Department of Aerospace and Mechanical Engineering |
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The Effect of Moisture Content on the Compressive Behavior of Concrete under Elevated Temperatures Description coming soon. Department of Civil Engineering and Geological Sciences |
Comparison of a Holographic Laser Interferometer to a Shack-Hartmann Sensor Description coming soon. Department of Aerospace and Mechanical Engineering |
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Measures of Similarity and Edge Weighting in Complex Multivariate Climate Networks Climate change is an issue of growing economic, social, and political concern. Continued rise in the average temperature of the Earth could lead to drastic climate change or an increased frequency of extreme events, which would negativelyaffect agriculture, population, and global health. One way of studying the dynamics of the Earth's changing climate is by attempting to identify regions that exhibit similar climatic behavior in terms of long-term variability. Climate networks have emerged as a strong analytics framework for both descriptive analysis and predictive modeling of the emergent phenomena. Previously, the networks were constructed using only one measure of similarity, namely the (linear) Pearson cross correlation, and were then clustered using a community detection algorithm. However, nonlinear dependencies are known to exist in climate, which begs the question whether more complex correlation measures are able to capture any such relationships. In this paper, we present a systematic study of different univariate measures of similarity and compare how each affects both the network structure as well as the predictive power of the clusters. Department of Computer Science and Engineering |
Anatomic Variation of Elastic Inhomogeneity and Anisotropy of Cortical Bone A recent study revealed anatomic variation in the magnitude and anisotropy of elastic constants along the entire femoral diaphysis of a single human femur (Espinoza Orías et al., 2009). The objective of this thesis was to confirm these trends across multiple donors while also considering effects of the anatomic quadrant, apparent tissue density, donor age, and donor gender by measuring experimental stiffness with ultrasonic wave propagation. A micromechanical model accounting for the effects of apatite crystal orientation distribution was combined with a finite element model accounting for the effects of intracortical porosity to determine the underlying structural features causing the experimental anatomic variation in the elastic anisotropy of cortical bone. Department of Aerospace and Mechanical Engineering |
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Development of a Scanning Probe Instrument for Measurement of Solid Electrolyte Conductivity Solid-state and thin-film electrolytes for advanced lithium batteries are of great interest today due to the safety and stability advantages in contemporary battery applications, such as portable electronics and electric vehicles. Desired characteristics of the product electrolytes are great stability and service life-time coupled with low electronic conductivity and high conductivity of lithium ions. Study of electrolyte conductivity has commonly been accomplished using electrochemical impedance spectroscopy (EIS) in a serial fashion. This paper describes development of an instrument for automated measurement of a thin-film composition gradient of solid electrolyte samples. Electrical contact to the sample is made through a mercury drop that is positioned under computer control. This system enables an experimenter to make a series of consecutive conductivity measurements across the surface of a thin film with ease. Accuracy in detection of the electrolyte bulk conductivity was verified by study of a proprietary glass electrolyte produced by Ohara, Inc. The sequential testing procedure was also studied using a thin film with a composition gradient. The gradient film was deposited using pulsed-laser deposition (PLD). Department of Chemical and Biomolecular Engineering |
CO2-Induced Phase Separations in Mixtures Containing Ionic Liquids The goal of this thesis is to study the phase behavior of three types of organic molecules, aromatics, paraffins and naphthenes, in pyridinium-based ionic liquid systems with carbon dioxide. Temperature, pressure and composition of the ionic liquid systems were varied to obtain the solubility of the these organics and carbon dioxide at those conditions. Molar volumes of the ionic liquids and their mixtures, as well as the volume expansion with increasing carbon dioxide pressure, were measured. Department of Chemical and Biomolecular Engineering |
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