Testing of Great Bay Oysters for Two Protozoan Pathogens

Two protozoan pathogens, Haplosporidium nelsoni (MSX) and Perkinsus marinus (Dermo) are known to be present in Great Bay oysters. With funds provided by the Piscataqua Region Estuaries Partnership (PREP), the Marine Fisheries Division of the New Hampshire Fish and Game Department (NHF&G) continues to assess the presence and intensity of both of these disease conditions in oysters from the major natural beds within the Great Bay estuarine system and at selected aquaculture sites. Histological examinations of Great Bay oysters have also revealed other endoparasites

Development and implementation of a topology and size optimized formula SAE chassis [abstract]

Abstract only availableThe design of the Formula SAE chassis is a critical component in producing a competitive car. An ideal frame is expected to be lightweight and stiff so that a degree of freedom can be removed from the the design of the suspension. Thus, the design of the frame can benefit from the implementation of optimization software in which constraints can be applied to the mass of the frame in order to reach a desired stiffness. The purpose of this project was to develop a process to optimize a Formula SAE chassis which could easily be used by future teams to analyze and develop optimized frames. Topology optimization was used to develop a general idea of how to acheive a stiff, lightweight design. Then a preliminary design was developed using the results of the topology optimization and the requirements of the frame as specified in the Formula SAE competition rules. Finally, size optimization furthered reduced the weight of the frame by optimizing the size of tubes. The completed frame design resulted in a 10 pound reduction of weight and a 20% increase in torsional stiffness.College of Engineering Undergraduate Research Option; National Science Foundatio

Nucleotide-dependent DNA gripping and an end-clamp mechanism regulate the bacteriophage T4 viral packaging motor.

ATP-powered viral packaging motors are among the most powerful biomotors known. Motor subunits arranged in a ring repeatedly grip and translocate the DNA to package viral genomes into capsids. Here, we use single DNA manipulation and rapid solution exchange to quantify how nucleotide binding regulates interactions between the bacteriophage T4 motor and DNA substrate. With no nucleotides, there is virtually no gripping and rapid slipping occurs with only minimal friction resisting. In contrast, binding of an ATP analog engages nearly continuous gripping. Occasional slips occur due to dissociation of the analog from a gripping motor subunit, or force-induced rupture of grip, but multiple other analog-bound subunits exert high friction that limits slipping. ADP induces comparably infrequent gripping and variable friction. Independent of nucleotides, slipping arrests when the end of the DNA is about to exit the capsid. This end-clamp mechanism increases the efficiency of packaging by making it essentially irreversible

Non-Isotropic Material Distribution Topology Optimization for Fused Deposition Modeling Products

Mechanical properties of products produced with the Fused Deposition Modeling (FDM) process are known to be dependent on bead direction, especially when short fiber reinforcement is added to the polymer filament feedstock. As a result, the structural performance of fiber-filled FDM parts is expected to be improved by simultaneously computing preferred deposition directions while optimizing the internal support structure. This paper presents a topology optimization method for computing the material distribution within a fiber-reinforced polymer composite FDM part that incorporates the non-isotropic mechanical properties of the bead structure. Unlike the well-established homogenization topology optimization method which determines pointwise orthotropic properties by increasing the complexity of the design problem, our approach takes advantage of the simplicity of the SIMP method where the underlying orthotropic orientation is assumed. Computed results show the effect that the orientation of fiber filled bead orthotropic microstructure has on part topology for 2D FDM parts.Mechanical Engineerin

Derivative observations in Gaussian Process models of dynamic systems

Gaussian processes provide an approach to nonparametric modelling which allows a straightforward combination of function and derivative observations in an empirical model. This is of particular importance in identification of nonlinear dynamic systems from experimental data. 1)It allows us to combine derivative information, and associated uncertainty with normal function observations into the learning and inference process. This derivative information can be in the form of priors specified by an expert or identified from perturbation data close to equilibrium. 2) It allows a seamless fusion of multiple local linear models in a consistent manner, inferring consistent models and ensuring that integrability constraints are met. 3) It improves dramatically the computational efficiency of Gaussian process models for dynamic system identification, by summarising large quantities of near-equilibrium data by a handful of linearisations, reducing the training size - traditionally a problem for Gaussian process models

3D finite element analysis of the acetabulum and interference fit for total hip arthroplasty [abstract]

Abstract only availableDemand for hip replacement surgery is rising with the increasing age of the human population. The effects of the cementless interference fit acetabular cups are not fully understood, and as such is the focus of the present research. The inserted cup being 2 mm larger in diameter than the reamed hip induces significant stresses upon the surrounding bone. The magnitude of the induced stresses within the hip impact the ingrowth of bone into the fixture. Therefore a complete understanding of these induced stresses from various implant designs will allow an analysis to be made to increase the useful part life preventing revision surgery. A full three dimensional finite element analysis is performed upon several different hip geometries constructed from CT scans and analyzed using various commercially available software packages (Amira, Rhinoceros, ProEngineer, Hypermesh, ABAQUS). The present study includes 5 different hips, each of which will be analyzed for the insertion of 3 different acetabular cup designs.College of Engineering Undergraduate Research Optio