<p> Air conditioning and heating comprised 47.7% of total energy usage in residential homes in the United States in 2009 equating to 4.86 quad (5.13 EJ) energy used. According to the U.S. Energy Information Administration (EIA) this is down from 58% in 1993. This is in large part due to the difference types of energy efficiency measures, from installing more efficient equipment to drafting better building codes that are inclusive of energy saving measures. Generally, these measures are very effective for new buildings. However, older buildings may still rely on less efficient materials and equipment thus inflating the building's energy usage.</p><p> The installation of simple dampers on the registers of a two-story, 2400 sq. ft. residential house as a retrofit measure to increase energy efficiency of its heating, cooling, and ventilation (HVAC) system is explored in this thesis. A residential house was modeled in EnergyPlus (v8.4), a whole-building energy simulation software available from the U.S. Department of Energy (DOE). The house was simulated for total energy usage with a typical HVAC system serving seven rooms; it was compared to a simulation of the same system with simple dampers installed on the registers.</p><p> It is shown that by installing dampers that self-fluctuate for local room temperatures, the system has an 11% reduction in energy usage in the Boston, Massachusetts climate zone. Additionally, the dampers are able to reduce hot and cold spots within the building and reduce, on average, the difference between the first and second floor temperatures. It is also shown that the effects of overpressurization of the HVAC system could be minor through an airflow simulation using CONTAM and EnergyPlus, but more experimentation is required. Seven other climate zones in the US were also simulated. </p>

<p> Diffusion flames exist in most practical combustors, and an accurate understanding of their structure is crucial to efficiency improvement and pollution suppression. A coflow laminar diffusion flame, which has well-defined boundary conditions, is the simplest configuration in which interactions between flow field and reactions can be readily modified and studied. Knowledge obtained from coflow laminar diffusion flames is not only of fundamental importance, but it also can facilitate the study of turbulent diffusion flames in practical industrial combustors.</p><p> In order to facilitate the computational investigation of laminar flames, a novel vorticityvelocity formulation of the Navier-Stokes equations &mdash; the Mass-Conserving, Smooth (MC-Smooth) vorticity-velocity formulation &mdash; is developed in this work. The governing equations of the MC-Smooth formulation include a new second-order Poisson-like elliptic velocity equation, along with the vorticity transport equation, the energy conservation equation, and N_spec species mass balance equations. The MC-Smooth formulation is compared to two pre-existing vorticity-velocity formulations by applying each formulation to confined and unconfined axisymmetric laminar diffusion flame problems For both applications, very good to excellent agreement for the simulation results of the three formulations is obtained. The MC-Smooth formulation requires the least CPU time and can overcome the limitations of the other two pre-existing vorticity-velocity formulations by ensuring mass conservation and solution smoothness over a broader range of flow conditions. In addition to these benefits, other important features of the MC-Smooth formulation include: (1) it does not require the use of a staggered grid, and (2) it does not require excessive grid refinement to ensure mass conservation.</p><p> The MC-Smooth formulation is then applied to two groups of coflow laminar diffusion flames of great fundamental and practical significance. In the first application, the influences of fuel dilution, inlet velocity, and gravity on the shape and structure of methane-air coflow laminar diffusion flames are investigated. A series of nitrogen-diluted flames measured in the Structure and Liftoff in Combustion Experiment (SLICE) on board the International Space Station is assessed numerically under microgravity and normal gravity conditions with CH₄ mole fraction ranging from 0.4 to 1.0, inlet fuel velocity ranging from 23 to 90 cm/s, and inlet coflow velocity ranging from 16 to 65 cm/s. Very good agreement between computation and measurement is obtained, and the major conclusions are as follows.</p><p> 1. Buoyant and nonbuoyant luminous flame lengths are proportional to the mass flow rate of the fuel mixture. Computed and measured nonbuoyant flames are noticeably longer than their 1 g counterparts. The effect of fuel dilution on flame shape is negligible when the flame shape is normalized by the methane flow rate. 2. Increasing coflow velocity reduces the size of the luminous flame shape, and the size of the luminous flame shape will decrease faster when gravity is eliminated or inlet fuel velocity is larger. 3. Soot volume fraction is very sensitive to variations in gravitational acceleration, fuel stream dilution, and inlet fuel velocity. Eliminating buoyancy, increasing fuel concentration, or increasing inlet fuel velocity will broaden and lengthen the sooting region of the flame, increasing the peak soot volume fraction, and shift its location to the vicinity of the flame wing region.</p><p> In the second application, the influence of fuel dilution and pressure on the structure and geometry of methane-air coflow laminar diffusion flames is examined A series of methane-fueled, nitrogen-diluted flames is investigated both computationally and experimentally, with CH₄ mole fraction ranging from 0.50 to 0.65 and pressure ranging from 1.0 to 2.7 atm. For a broad spectrum of flames at atmospheric and elevated pressures, very good agreement between computation and measurement is obtained, and the major conclusions are as follows. (1) Maximum temperature increases monotonically with increasing CH₄ concentration or pressure, while the peak temperature along the centerline changes in a non-monotonic way with respect to pressure. (2) Flame radius at a given height decreases with pressure approximately as <i> r</i>_f &prop; <i>P</i>^-1/2, and modified flame length is roughly independent of pressure. (3) Inclusion of a soot model significantly reduces the peak temperature along the centerline, and its effects on the maximum temperature and flame geometry are minor.</p>

<p>One of the major environmental challenges facing our planet and living beings is the global warming. This phenomena, known as the gradual increase in the overall temperature of earth's atmosphere is mostly caused by the greenhouse eect which is a result of increased levels of greenhouse gases. Major constitutes of these gases are Carbon Dioxide (CO2) and Nitrogen Oxides (NOx). Transportation sector is responsible for releasing a signicant portion of these gases into the atmosphere. In recent decades, many endeavors such as using alternative fuels and modications in engine cycles have been made to control the amount of pollutants emitted from internal combustion engines. In this work, the impact of adding humidity to the input Oxidizer stream on reduction of NOx and Carbone Dioxide (CO2) of a CNG engine has been studied. With the addition of the humidity, the combustion temperature will be reduced which improves the engines lifespan. Non-Premixed combustion process in a single cylinder is simulated using the STAR CCM+ software from CD-Adapco company, using the Presumed Probability Density Function (PPDF) combustion model which is an accurate model for combustion. Simulation results indicate with 10% humid air, signicant reductions in NOx and CO2 are obtained, with a moderate increase in CO output. Adding humidity results in total emission reduction.

Concentric tube robots are needle-diameter robots consisting of multiple precurved, nested, superelastic tubes. They can be made to controllably elongate and bend by grasping the tubes at their bases and applying axial rotation and translation to each tube independently. This causes the tubes to bend and twist one another. This dissertation presents modeling, analysis, and design of these robots for medical uses as both robotic manipulators and steerable needles. The design of a robotic system for endoscopic endonasal surgery is presented, and a novel electrical technique for creating custom tube curvatures is described. The elastic stability of concentric tube robots is modeled and analyzed to provide design conditions for stability and a stability indicator that characterizes the relative stability of the robot based on its configuration. When used as a needle, the shaft of the robot must always remain along the path traced by the tip, as the robot elongates. Necessary and sufficient design and actuation conditions are presented that result in this behavior, and approximations of it are also considered. Lastly, a method is developed and experimentally characterized for mechanics-based force sensing using knowledge of the robot stiffness and position and/or orientation measurements along the shaft of the robot.

Toward improving surgery and patient care, this work presents the development of needle-sized surgical tools and robotic systems that incorporate distal articulation mechanisms. In the human body, there are numerous critical locations that are difficult or impossible to reach safely in a minimally-invasive fashion using existing tools and approaches. In this work, a new articulated steerable needle and miniature wrist are developed for needle-sized tools. Geometry and mechanics inform the design of these articulating devices, and models are developed to predict their behavior. Using these articulating tools, robotic systems are created for the treatment of lung and skull base cancers toward providing minimally-invasive access to these difficult to reach locations in the body.

<p> In Roll-to-Roll (R2R) manufacturing, efficient transport of flexible materials (webs) on rollers requires simultaneous control of web speed and tension. Webs experience disturbing forces during transport due to nonideal machine elements and processes such as printing, coating, lamination, etc. Since rotating machine elements are employed, these disturbances are in the form of periodic oscillations in web tension and speed. Design of efficient model-based web tension and speed control systems employing both feedback and feedforward actions that can adapt to changes in parameters and reject periodic disturbances were investigated in this research. Tools from adaptive and robust control theory and singular perturbation method were utilized for the design and analysis of these control systems. </p><p> Model reference and relay feedback based adaptive Proportional-Integral (PI) tension control schemes were developed to regulate web tension; these schemes overcome the tedious tuning procedures required for fixed gain PI schemes when process parameters and conditions change. To directly control the roll speed when belt-pulley and gear transmissions are employed, a control scheme that uses both motor and load speed feedback is developed. In the presence of a compliant transmission system, it is shown that using pure load speed feedback must be avoided as it results in an unstable system. In situations where linearization of the nonlinear web tension governing equation is not possible due to changes in operating conditions, a nonlinear tension regulator is designed via a solution method employed in the nonlinear servomechanism problem. The feedforward action is synthesized by considering a discretized form of the tension governing equation in conjunction with adaptive estimation of periodic disturbance parameters. It is also shown that interaction between different subsystems of the R2R system may be minimized by employing feedforward action. The strategy of utilizing tension signal from the web tension zone downstream of the driven roller is shown to result in minimization of propagation of disturbances into further downstream tension zones. For each of the developed designs, experiments were conducted on a large R2R platform for different web materials and transport conditions to evaluate and compare their performance. Implementation guidelines are provided for ease of applying the designs to other industrial R2R machines.</p>

Microfluidic platforms are extremely promising for cell and tissue culture by greatly reducing costs while opening doors of opportunity for biological assays that were not feasible previously. The capability of precise spatiotemporal control of microenvironments enables new assays to probe the physiological and pathological behaviors of cells and tissues. Integration of advanced sensing technologies with microfluidics allows for probing phenomena within cells and tissue. This dissertation presents microfluidic platforms for localized probing of whole retina tissue, which has the advantages of easy accessibility, highly organized structure, and unique light sensitivity. These platforms allow for spatially isolated chemical and electrical stimulation and detection of cell signaling events in whole retina tissue. The Retina-on-a-Chip platform has achieved localized point application of reagents to the surface of the retina while maintaining tissue health over a long-term culture. When integrated with graphene transistors, this platform provides the opportunity to also probe electrical signaling events. As a key component in the Retina-on-a-Chip platform, the thin-film PDMS layer was found challenging to fabricate, thus current fabrication techniques were analyzed and new approaches were examined.

This thesis describes the control and assessment of a powered transfemoral prosthesis for improving amputee stair ascent. It begins with motivation for the work and a description of current lower-limb prosthetic technology. Then it explains the finite-state-based impedance-admittance control philosophy and implementation for both the knee and the ankle joints of a powered prosthesis. Next, it presents experimental assessments and evaluates the effectiveness of the device and controller at reducing metabolic effort and improving joint biomechanics for three transfemoral amputee subjects climbing stairs. These sections finish with general conclusions regarding the biomechanical and energetic benefits of this technology.

<p> Heat sinks are a critical component in numerous thermal management strategies, ranging from consumer electronics to data centers. The ability to perform an accurate thermal performance analysis of a heat sink is a crucial step in the design process. In situations where the heat sink is larger in area than the component it is being used to cool, a phenomena known as thermal spreading resistance takes effect. Thermal spreading resistance is not as easily calculated as other components of the thermal resistance of a heat sink (i.e. material and external thermal resistance). However, multiple solutions have been proposed and published that can be used to calculate thermal spreading resistance. The difficulty lies in that most of these solutions contain a very complex set of equations and are not very practical for use by the industry. As a result, the present research is aimed at developing a simple equation that can be used to calculate the thermal spreading resistance of a heat sink based on certain geometric and thermal characteristics. Using a commercial CFD software package, a model was developed that was shown to accurately model the spreading resistance within a heat. Using this model, a set parametric studies was conducted that varied the base thickness, heat source/heat sink side length ratio, heat sink material, external resistance, and the aspect ratio in order to obtain the effects they have on the spreading resistance. Using these results, an extensive data analysis was conducted and resulted in the development of a much simpler equation that can be used to calculate the thermal spreading resistance of heat sink. The developed equation was shown to be in excellent agreement with previous analytical solutions, in most cases with +/- 5%. As a result, it was confirmed that the developed equation can be used to accurately calculate spreading resistance over the stated range of valid parameters.</p>

In recent years, robotic rehabilitation has proven to be beneficial for individuals with impaired limbs, particularly due to the potential of robotic therapists to be more accessible, consistent and cost-effective than their human counterparts. While pursuing better rehabilitation methods is a crucial endeavor, it is also important to acknowledge that many people need an alternative form of assistance for physical impairments, both while undergoing rehabilitation and in the unfortunate but common scenario of rehabilitation providing insufficient improvements. The aim of this thesis is to present a low-cost robotic assistive device which may serve as a complement to rehabilitation procedures. The proposed system determines the intended movement of a users upper arm via eye-gaze inputs and force inputs, and physically assists said movement. In this manner, the system may provide immediate relief for someone suffering from physical impairments in their upper limbs, either as a complement to ongoing rehabilitation therapy or as a partial solution in the case of insufficient improvements from rehabilitation.