abstract: Harsh environments have conditions that make collecting scientific data difficult with existing commercial-off-the-shelf technology. Micro Electro Mechanical Systems (MEMS) technology is ideally suited for harsh environment characterization and operation due to the wide range of materials available and an incredible array of different sensing techniques while providing small device size, low power consumption, and robustness. There were two main objectives of the research conducted. The first objective was to design, fabricate, and test novel sensors that measure the amount of exposure to ionizing radiation for a wide range of applications including characterization of harsh environments. Two types of MEMS ionizing radiation dosimeters were developed. The first sensor was a passive radiation-sensitive capacitor-antenna design. The antenna's emitted frequency of peak-intensity changed as exposure time to radiation increased. The second sensor was a film bulk acoustic-wave resonator, whose resonant frequency decreased with increasing ionizing radiation exposure time. The second objective was to develop MEMS sensor systems that could be deployed to gather scientific data and to use that data to address the following research question: do temperature and/or conductivity predict the appearance of photosynthetic organisms in hot springs. To this end, temperature and electrical conductivity sensor arrays were designed and fabricated based on mature MEMS technology. Electronic circuits and the software interface to the electronics were developed for field data collection. The sensor arrays utilized in the hot springs yielded results that support the hypothesis that temperature plays a key role in determining where the photosynthetic organisms occur. Additionally, a cold-film fluidic flow sensor was developed, which is suitable for near-boiling temperature measurement. Future research should focus on (1) developing a MEMS pH sensor array with integrated temperature, conductivity, and flow sensors to provide multi-dimensional data for scientific study and (2) finding solutions to biofouling and self-calibration, which affects sensor performance over long-term deployment. / Dissertation/Thesis / Ph.D. Engineering 2013

The non-contact nature of magnetic actuation makes it useful in a variety of microscale applications, from microfluidics and lab-on-a-chip devices to classical MEMS or even microrobotics. Ferromagnetic materials like nickel are particularly attractive, because they can be easily deposited and patterned using traditional lithography-based microscale fabrication methods. However, the response of ferromagnetic materials in a magnetic field can be difficult to predict. When placed in a magnetic field, high magnetization is induced in these ferromagnetic materials, which in turn generates force and/or torque on the ferromagnetic bodies. The magnitude and direction of these forces are highly dependent on the type of material used, the volume and aspect ratio of the ferromagnetic material, as well as the spatial distribution and magnitude of the magnetic field. It is important to understand these complex interactions in order to optimize force and torque generated, particularly given common limitations found in microfabrication, where it is often challenging to deposit large volumes of ferromagnetic material using conventional microdeposition methods, and power availability is also often limited, which in turn limits the ability to generate strong electromagnetic fields for actuation. This work represents a theoretical analysis and experimental validation in macro scale to determine best practices when designing ferromagnetic actuators for microscale applications. Specifically, the use of nickel thin film prisms actuated in spatially uniform electromagnetic fields. These constraints were chosen because uniform magnetic fields can be readily generated with a simple and inexpensive Helmholtz coil design, and the uniformity makes actuation force independent of location, minimizing the need for spatial precision in devices. Nickel can also be easily deposited using evaporation or sputtering, generally in forms of thin-films.

Les nouvelles générations d’avions, tant civils que militaires, sont désormais pleinement engagées dans l’électrification des commandes de vol. Afin d’atteindre les nouveaux objectifs et critères mis en place pour le bon développement de ces actionneurs électro-mécaniques, il est nécessaire d’effectuer des études en amont. Ces études portent principalement sur le comportement mécanique et tribologique des pièces en contact afin d’éviter l’évènement le plus redouté qui est le grippage, au sens blocage irréversible du système. En effet, ces actionneurs électro-mécaniques sont soumis à des sollicitations de chargement vibratoires qui induisent des déplacements de très faibles amplitudes entre les pièces en contact. Ces micro-glissements peuvent induire de l’usure, de la fissuration, de l’écaillage, etc. Pour répondre à ces objectifs, les travaux de recherche menés dans cette thèse, ont porté sur quatre axes majeurs. Le premier axe consiste à étudier et déterminer le comportement tribologique des premiers corps en milieu sec, puis en incorporant des traitements de surface. Le second axe a permis de déterminer les différents régimes de lubrification du contact lubrifié à la graisse. Nous avons montré que le régime de lubrification totale est caractérisé par la formation d’un tribofilm lubrifiant et protecteur. Des analyses plus poussées ont portées sur les cinétiques de formation et destruction de ce tribofilm ainsi que sa nature. Le troisième axe est consacré à l’étude du comportement tribologique du contact revêtu en milieu graissé. Le dernier axe de travail est destiné à la mise en place d’outils de simulation et de prévision de l’usure, et donc à posteriori du grippage, en fonction des conditions de chargement. Ces quatre axes d’études complémentaires ont donc permis de mettre en place des outils de comparaison de graisses et de revêtements, de comprendre le comportement du contact étudié ainsi que de développer des outils de simulation. / Electrification of flight controls represents an important milestone for both civil and military next-generation aircraft. A successful development of electro-mechanical actuators used for this type of application not only requires the establishment of a set of appropriate objectives and criteria but also the study of fundamental aspects. These studies mainly focus on the mechanical and tribological behavior of parts in contact with the objective to prevent seizing. Seizing is defined as an irreversible blockage of the system and it can be considered as the worst-case scenario. As a matter of fact, the considered electro-mechanical actuators are subjected to vibrational loads which induce small displacements between the parts in contact. These micro-slidings can result in wear, cracking, scaling and other undesirable phenomena. This PhD thesis is divided into four major topics that each contributes to prevent seizing. More precisely, the first part of this thesis deals with the tribological behavior of the first bodies in dry condition both with and without surface treatments. As a second axis the different lubrication regimes of the greased lubricated interface were determined. We have shown that the total lubrication regime is characterized by the formation of a lubricant and protective tribofilm. A detailed analysis on the nature of the tribofilm as well as on its kinetics of formation and destruction was carried out. The third area is devoted to the study of the tribological behavior of the coated and greased contact. Finally, the fourth axis of this research deals with the question of how we can simulate and predict wear, and seizing as its most severe form, under multiple loading conditions. These four complementary areas allowed us to establish tools for comparison for greases and coatings in order to understand the behavior of the fretted interface and to develop simulation tools.

The development of voltage source converter (VSC) based high voltage direct current (HVDC) transmission has progressed rapidly worldwide over the past few years. The UK transmission system is going through a radical change in the energy landscape which requires a number of VSC HVDC installations to connect large Round 3 windfarms and for interconnections to other countries. For bulk power long distance transmission, VSC HVDC technology offers flexibility and controllability in power flow, which can benefit and strengthen the conventional AC system. However, the associated uncertainties and potential problems need to be identified and addressed. To carry out this research, integrated mathematical dynamic AC/DC system models are developed in this thesis for small disturbance stability analysis. The fidelity of this research is further increased by developing a dynamic equivalent representative Great Britain (GB) like system, which is presented as a step-by-step procedure with the intention of providing a road map for turning a steady-state load flow model into a dynamic equivalent. This thesis aims at filling some of the gaps in research regarding the integration of VSC HVDC technology into conventional AC systems. The main outcome of this research is a systematic assessment of the effects of VSC controls on the stability of the connected AC system. The analysis is carried out for a number of aspects which mainly orbit around AC/DC system stability issues, as well as the control interactions between VSC HVDC and AC system components. The identified problems and interactions can mainly be summarized into three areas: (1) the effect of VSC HVDC controls on the AC system electromechanical oscillations, (2) the potential control interactions between VSC HVDC and flexible alternating current transmission systems (FACTS) and (3) the active power support capability of VSC HVDC for improving AC system stability. The effect of VSC controls on the AC system dynamics is assessed with a parametric sensitivity analysis to highlight the trade-offs between candidate VSC HVDC outer control schemes. A combination of analysis techniques including relative gain array (RGA) and modal analysis, is then applied to give an assessment of the interactions – within the plant model and the outer controllers – between a static synchronous compensator (STATCOM) and a VSC HVDC link operating in the same AC system. Finally, a specific case study is used to analyse the capability of VSC HVDC for providing active power support to the connected AC system through a proposed frequency droop active power control strategy.

Modern 'more-electric' aircraft demand increased levels of electrical power as non-propulsive power systems are replaced with electrical equivalents. This electrical power is provided by electrical generators, driven via a mechanical transmission system, from a rotating spool in the gas turbine core. A wide range of electrical loads exist throughout the aircraft, which may be pulsating and high powered, and this electrical power demand is transferred though the generators to produce a torque load on the drivetrain. The mechanical components of the drivetrain are designed for minimum mass and so are susceptible to fatigue, therefore the electrical loading existing on modern airframes may induce fatigue in key mechanical components and excite system resonances in both mechanical and electrical domains. This electro-mechanical interaction could lead to a reduced lifespan for mechanical components and electrical network instability.This project investigates electro-mechanical interaction in the electrical power offtake from large diameter aero gas turbines. High fidelity modelling of the drivetrain, and generator, allow the prediction of system resonances for a generic gas turbine-generator system. A Doubly-Fed Induction Generator (DFIG) is considered and modelled. DFIGs offer opportunities due to their fast dynamics and their ability to decouple electrical and mechanical frequencies (e.g. enabling a constant frequency electrical system with a variable speed mechanical drive). A test platform is produced which is representative of a large diameter gas turbine and reproduces the electro-mechanical system behaviour. The test platform is scaled with respect to speed and power but maintains realistic sizing between component dimensions which include: a gas turbine mechanical spool emulation, transmission driveshafts and gearbox, and accessory loads such as a generator. This test platform is used to validate theoretical understanding and suggest alternative mechanical configurations, and generator control schemes, for the mitigation of electro-mechanical interaction.The novel use of a DFIG and an understanding of electro-mechanical interaction allow future aircraft designs to benefit from the increased electrification of systems by ensuring that sufficient electrical power can be provided by a robust gas turbine-generator system.

A method for tuning the spring rate and damping rate of a mountain bike suspension based on a data-driven procedure is presented. The design and development of a custom data acquisition system, known as the MTB~DAQ, capable of measuring acceleration data at the front and rear axles of a bike are discussed. These data are input into a model that is used to calculate the vertical acceleration and pitching angular acceleration response of the bike and rider. All geometric and dynamic properties of the bike and rider system are measured and built into the model. The model is tested and validated using image processing techniques. A genetic algorithm is implemented with the model and used to calculate the best spring rate and damping rate of the mountain bike suspension such that the vertical and pitching accelerations of the bike and rider are minimized for a given trail. Testing is done on a variety of different courses and the performance of the bike when tuned to the results of the genetic algorithm is discussed. While more fine tuning of the model is possible, the results show that the genetic algorithm and model accurately predict the best suspension settings for each course necessary to minimize the vertical and pitching accelerations of the bike and rider.

This Thesis describes the design, assembly, programming, and evaluation of the BLDS-M-RAKE, the newest addition to the family of devices called the Boundary Layer Data System (BLDS). The BLDS-M-RAKE is a continuation of the BLDS-M series of devices, a modular approach with updated electronics for boundary layer measurements. The BLDS-M-RAKE records data from a number of sensors, intended to be routed to an array of probes, or rake. Through preliminary testing, a new flexible manifold design from molded silicone and the hardware used on the RFduino development boards from the BLDS-M proof-of-concept modules were validated for use in the final prototype design. A PCB was designed to house a Simblee System on a Chip (SOC), 11 Honeywell pressure sensors, a microUSB socket, a microSD socket, a DC-DC boost regulator, and two AAA cells. The SOC was then programmed in C++ with the Arduino IDE. The Simblee was programmed to prompt a user over a serial monitor to confirm test parameters from a configuration file and then coordinates the reading and recording of sensor data during a flight test. Problems after assembly did not allow a full evaluation of the board, but the following was concluded: the sleeping board current draw was less than 3 mA and the peak current draw was less than 30 mA. The sensors could be sampled at 100 Hz and recorded to the microSD card. The flexible manifolds molded from silicone are viable for future designs.

Observing the dynamic interaction between stars and their close stellar neighbors is key to establishing the stars’ orbits, masses, and other properties. Our ability to visually discriminate nearby stars is limited by the power of our telescopes, posing a challenge to astronomers at small observatories that contribute to binary star surveys. Masks placed at the telescope aperture promise to augment the resolving power of telescopes of all sizes, but many of these masks must be manually and repetitively reoriented about the optical axis to achieve their full benefits. This paper introduces a design concept for a mask rotation mechanism that can be adapted to telescopes of different types and proportions, focusing on an implementation for a Celestron C11 Schmidt–Cassegrain optical tube assembly. Mask concepts were first evaluated using diffraction simulation programs, later manufactured, and finally tested on close double stars using a C11. An electronic rotation mechanism was designed, produced, and evaluated. Results show that applying a properly shaped and oriented mask to a C11 enhances contrast in images of double star systems relative to images captured with the unmasked telescope, and they show that the rotation mechanism accurately and repeatably places masks at target orientations with minimal manual effort. Detail drawings of the mask rotation mechanism and code for the software interface are included.

Fried foods are delicious and enjoyed by almost everyone. However, they are not the healthiest foods to eat because of the amount of oil they contain. This thesis, sponsored by Moaero Company founder, Mr. Harrish Bhutani, intends to determine whether a simply designed centrifuge system can remove a reasonable amount of oil from fried foods after it has been deep fried without adversely affecting the texture of the fried food. Due to a large variety in the texture as well as the type of fried foods, and in order to keep the scope of this thesis more focused and feasible, the focus of this investigation will be French fries. Three variables are tested: the type of fry, the angular velocity of the centrifuge, and the time spent in the centrifuge. Multiple designs for the centrifuge system were made on SolidWorks. Engineer Equation Solver (EES) was used to aid steady state and transient heat transfer calculations. Minitab was used for statistical analysis. The impact of various parameters on the change in mass of the French fries, as a measure for evaluating the oil content, were studied. The results indicate whether a centrifuge will remove a reasonable amount of oil while also considering the integrity of the fries. The study concludes that centrifugation is be a cost-effective method for removing oil from fried foods.

Design and construction of machine respects the needs of the manufactory of delicatessen. In my technical report there were also project several drives and there were described main structural parts of the machine.