The development of easily fabricated, highly stable DNA-based microarray and continuous flow concentrating devices is vital for several biomedical and environmental applications. Nucleic acid biosensors can be used for genetic analysis, disease diagnosis, drug discovery, food and water quality control and more, however methods of fabrication are tedious, and the longevity of sensors is compromised by the fragility of the sensing component. In this report, the fabrication and characterization of two biosensing modalities – microarrays and microgels – composed of Rolling Circle Amplification (RCA) product in poly(oligoethylene glycol methacrylate) (POEGMA) hydrogels are investigated. RCA product microarrays were developed by the sequential printing of aldehyde and hydrazide functionalized POEGMA precursors on nitrocellulose paper, exploiting rapid gelling via hydrazone crosslinking to generate thin film hydrogel sensing arrays. POEGMA/RCA product microgels for affinity column applications were synthesized using an inverse emulsion polymerization technique. Inkjet printing evenly deposited RCA product in all wells, with POEGMA effectively stabilizing DNA on the cellulose substrate. Hybridization of complementary probe to the encapsulated RCA product was optimized, yielding a signal to noise ratio of ~4 for a large range of probe concentrations. Microgels were successfully synthesized in the size range of 10-60 μm diameter, and a linear model that can accurately predict size based on initiator and emulsifier concentration was developed. The encapsulation efficiency of RCA product in different sized microgels was explored, with larger microgels entrapping more product and the highest encapsulation efficiency calculated at 56%. These results demonstrate that POEGMA hydrogels can be utilized to encapsulate and stabilize RCA product in two distinct structures, providing a basis for the development of easily fabricated biosensors for more specific applications. / Thesis / Master of Applied Science (MASc)

No description available.

The effect of normal load, contact velocity, and dwell time on the coefficient of adhesion at slip in braking was investigated. A test rig that simulated locomotive wheel/rail interactions was used for the experimentation. The results indicated a drop in the coefficient of adhesion with increasing speed. However, normal load, contact velocity, and dwell time, as operating variables, did not have any effect on the variation of the coefficient of adhesion. A description of the investigation and recommendations for further studies is included. / Master of Science

A method for determining the maximum control moments required for an aircraft to perform a velocity vector roll is investigated. The velocity vector roll is assumed to occur at constant angle of attack, constant velocity, and zero sideslip. A simplified set of equations is developed for the non dimensional control moments about the three principal body axes. These equations take on a form well suited for numerical optimization methods. The Schittkowski sap optimization code is used to provide fast, accurate solutions. The numerical method also shows the advantage of being adaptable to changing the airframe and flight performance parameters. An exercise to find the global control moment maxima was performed for a an F-18 with constant aerodynamic derivatives and a load factor of one. The optimization was run for a range of discrete steady state roll rates, roll mode time constants and velocities. The results showed trends for the maxima to occur at the highest steady state roll rate parameter, smallest roll mode time constant and lowest velocity. Each control axis maximum is specific to a particular orientation and angle of attack. For the roll axis, the maximum occurs at nearly zero angle of attack and 270 of wind axis bank angle. The yaw axis maximum occurs at the largest angle of attack (70) and 90 of wind axis bank angle. The pitch maximum occurs near 270 of wind axis bank and 55 angle of attack, but is highly sensitive to the selection of Cma . All control moment maxima occur at a flight path angle of O. The roll and yaw control moment maxima occur upon a maximum roll input starting from rest at the specified orientation and angle of attack. The pitch control maximum occurs at the steady state roll rate when the proper orientation and angle of attack is encountered. / Master of Science

O presente trabalho destina-se à discussão sobre o cálculo de vida útil de rolamentos. Mostrando o avanço do processo de cálculo ao longo das décadas até o mais alto grau de desenvolvimento atual. A preocupação do texto é demonstrar de forma simples e objetiva as divergências que existem entre a formulação teórica e a real vida dos rolamentos, no que tange a fadiga de contato. Neste contexto foram realizados testes, em máquina especialmente destinada ao ensaio da fadiga de rolamentos. Variando-se para as duas séries de ensaios, apenas, a temperatura (aproximadamente 85°C e 110°C). Os resultados obtidos indicam que a vida real dos rolamentos apresenta grande divergência se comparada com a vida útil calculada, principalmente, no regime com maior temperatura. Atribui-se a esta disparidade, a ausência de cálculos precisos quanto à correlação da vida útil com o fator l, que é uma forma de se calcular o espaçamento entre as superfícies de contato, e o não emprego do cálculo do fator de carga, na formulação da vida útil de rolamentos. / The present work has the purpose of discussing the life of rolling bearings, describing the evolution of bearing life calculation until its current state of the art. Our focus is to demonstrate, simply and objectively, the inconsistencies occurring between the actual life of rolling bearings and their theoretical fatigue life estimation. For such purpose, tests were developed in a special bearing test rig to assess bearing fatigue. Two test sets were carried out with temperature being the only variation (approximately 85°C and 110°C). Results obtained from these tests suggest that the real life of rolling bearings is indeed very different from calculated bearing life, especially under higher temperature. Such disparity can be attributed to the lack of a precise computation of the relationship between bearing real life and the l factor - which determines the thickness of lubricant separating raceways and balls - as well as to the failure to compute the load factor in bearing life estimation.

Ces travaux de thèse concernent l’étude des effets des oscillations de faibles amplitudes sur la durée de vie en fatigue de contact pour des composants d’actionneurs de vol. Des outils théoriques et expérimentaux ont pour cela été employés.Un modèle semi-analytique de contact rugueux élasto-plastique a été codé puis utilisé. Celui-ci, couplé au modèle de Dang Van, a permis de réaliser une étude théorique de l’influence du sens de passage de contacts sur la durée de vie en fatigue. Une comparaison en fatigue entre mouvements continus et mouvements oscillants a ainsi pu être faite.Un banc bi-disque a été spécifiquement développé chez UTAS pour pouvoir réaliser des essais de fatigue de roulement aussi bien en mouvements continus qu’en mouvements oscillants. Des essais de lubrification ont été réalisés sur des éprouvettes en XD15NW et en CX13VD afin de caractériser le phénomène de faux effet Brinell. Des essais de fatigue en lubrification optimale ont finalement été réalisés sur les éprouvettes en XD15NW en mouvements continus et en mouvements oscillants, les résultats ont été comparés et mis en vis-à-vis avec ceux de l’analyse théorique. / This PhD thesis is a study of small reciprocating motions effects on contact fatigue life of flight actuator components. Theoretical and practical tools are used for this purpose.A semi-analytical elasto-plastic rough contact code has been implemented and, then, used. This code, associated with Dang Van model, allowed us to perform a theoretical study of rolling direction effect on fatigue life. A comparison has been made between continuous motions and reciprocating motions.A twin-disc test bench has been specifically design at UTAS to allow us to perform rolling fatigue tests with continuous motions or with reciprocating motions. Lubrications tests have been done on XD15NW and CX13VD samples in order to study false brinelling phenomenon. Finally, fatigue tests in ideal lubrication conditions have been done on XD15NW samples with continuous motions and with reciprocating motions, results have been cross-checked each other and cross-checked with theoretical results.

Profile strips have been used in various industries and now the demand of profile strip is still growing. Due to different reductions at different parts of the strips, profile strips after rolling generate a defect which looks like a wave. This study will design and manufacture a four-high profile rolling mill, which can roll profile strips. Experiments and finite element simulation are conducted to discuss the effects of different parameters on strip size and the defect of the profiled strips. In this study, a finite element analysis software is used to establish profile rolling models with different material setting mode, reduction, temperature, material, tension, and roll shape. From the simulation results, the effects of these parameters on the defects are discussed. Secondly, profiled rolls are designed and a heating equipment is added on the four-high rolling mill, and rolling experiments with different reduction, materials, passes of process, roll shape and temperature are conducted. From the experimental results the effects of these parameters on size of the defect of profile strip are discussed. Finally, from the comparisons between simulation results and experiment results, the feasibility of finite element models are verified.

<p>The rolling isolation system (RIS) studied in this dissertation functions on the principle of a rolling pendulum; an isolated object rests on a steel frame that is supported at its corners by ball-bearings that roll between shallow steel bowls, dynamically decoupling the floor motion from the response of the object. The primary focus of this dissertation is to develop predictive models that can capture experimentally-observed phenomena and to advance the state-of-the-art by proposing new isolation technologies to surmount current performance limitations. To wit, a double RIS increases the system's displacement capacity, and semi-active and passive damped RISs suppress the system's displacement response.</p><p>This dissertation illustrates the performance of various high-performance isolation strategies using experimentally-validated predictive models. Effective modeling of RISs is complicated by the nonholonomic and chaotic nature of these systems which to date has not received much attention. Motivated by this observation, the first part of this dissertation addresses the high-fidelity modeling of a single, undamped RIS, and later this theory is augmented to account for the double (or stacked) configuration and the supplemental damping via rubber-coated bowl surfaces. The system's potential energy function (i.e. conical bowl shape) and energy dissipation model are calibrated to free-response experiments. Forced-response experiments successfully validate the models by comparing measured and predicted peak displacement and acceleration responses over a range of operating conditions.</p><p>Following the experimental analyses, numerical simulations demonstrate the potential benefits of the proposed technologies. This dissertation presents a method to optimize damping force trajectories subject to constraints imposed by the physical implementation of a particular controllable damper. Potential improvements in terms of acceleration response are shown to be achievable with the semi-active RIS. Finally, extensive time-history analyses establish how the undamped and damped RISs perform when located inside biaxial, hysteretic, multi-story structures under recorded earthquake ground motions. General design recommendations, supported by critical-disturbance spectra and peak-response distributions, are prescribed so as to ensure the uninterrupted operation of vital equipment.</p> / Dissertation

No description available.

Thesis (Ph. D.)--Ohio University, November, 2002. / Title from PDF t.p. Includes bibliographical references (leaves 164-171).