Mechanical Engineering Commons^™

Investigation Of The Performance Of Flexible Pavement Systems Under Moving Loads Using Finite Element Analyses, Dona Jacqueline Johnson

Theses and Dissertations

The introduction of larger and heavier aircraft with more complex wheel configurations is making the current design methods inadequate for airfield pavements. In addition, airport pavements experience significant wander. However, the effect of wander on airport pavement performance has not been evaluated. In previous studies, the stress interactions between each tire of a triple-dual-tandem (TDT) axle used on B-777 and A380 aircraft cannot be captured using a two-dimensional model. In addition, many of these studies have assumed a linear-elastic material behavior of the pavement layers.

The purpose of this study is to conduct a three-dimensional finite element analysis to quantify …

Assessment Of Alternative Maritime Power (Cold Ironing) And Its Impact On Port Management And Operations., Richard Fiadomor

World Maritime University Dissertations

No abstract provided.

Energy Conservation In The Trinidad Tourist Industry Training Program, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

This Final Report summarizes the work performed by the Florida Solar Energy Center/University of Central Florida on the contract entitled "Energy Conservation in the Trinidad Tourist Industry Training Program". This program was performed for the Ministry of Tourism, Trinidad and Tobago, WI. (MoTTT) for the period September 1 to November 1, 2008. The MoTTT established a program for the tourist industry to facilitate learning about energy conservation and renewable energy technologies appropriate for resort applications on the Island of Trinidad. The Florida Solar Energy Center provided assistance through consulting, in education about energy technologies. FSEC modified existing energy training courses …

Attitude Estimation And Maneuvering For Autonomous Obstacle Avoidance By Miniature Air Vehicles, James K. Hall

Theses and Dissertations

Utilizing the Euler-Rodrigues symmetric parameters (attitude quaternion) to describe vehicle orientation, we develop a multiplicative, nonlinear (extended) variation of the Kalman filter (MEKF) to fuse data from low-cost sensors. The sensor suite is comprised of gyroscopes, accelerometers, and a GPS receiver. In contrast to the common approach of using the complete vehicle attitude as the quantities to be estimated, our filter states consist of the three components of an attitude error vector. In parallel with the time update of the attitude error estimate, we utilize the gyroscope measurements for the time propagation of the attitude quaternion. The accelerometer and the …

2008 Fall Engr333 Project Final Report, 2008 Fall Engr333

ENGR 333

The Calvin College Engineering 333 class of 2008 was challenged with the question, “What would it take to implement an energy efficiency fund at Calvin?” Before addressing this question, another had to be asked: “What is an energy efficiency fund?” An energy efficiency fund is a revolving fund which takes seed money from donations, tuition, or grants and invests it into projects that save energy. Energy cost savings from the projects are routed back to the fund to help it grow and enable it to finance future projects. In order to begin this, the senior engineering students began organizing and …

Characterization Of The Thermal Transport Through A Temporally-Varying Ash Layer, Darron Palmer Cundick

Theses and Dissertations

Ash deposits in commercial coal-fired boilers frequently pose serious maintenance challenges and decrease thermal efficiency. A better understanding of fundamental thermal transport properties in ash deposits can help mitigate their negative effects. In order to characterize the thermal properties of boiler-side deposits, this work presents a thermal transport model and in-situ measurements of effective thermal conductivity in coal ash deposits. A simple model of the thermal transport through an ash deposit, with and with out slagging, was developed. The model approximates the deposit by dividing it into four regimes: particulate, sintered, solidified slag, and molten slag. The development of this …

Green And High Performance Factory Crafted Housing, Florida Solar Energy Center, Stephanie Thomas-Rees

FSEC Energy Research Center®

In the U.S., factory-built housing greater than 400 square feet is built either to the U.S. Department of Housing and Urban Development (HUD) code for mobile homes or site-built codes for modular housing. During the last few years, as the production of HUD code housing has dwindled, many leading edge factory builders have started building modular homes to compete with site-built housing and stay in business. As part of the Building America Industrialized Housing Partnership (BAIHP) we have assisted in the design and construction of several 'green' and high performance modular homes that Palm Harbor Homes, Florida Division (PHH) has …

Energy Impacts Of Various Residential Mechanical Ventilation Strategies, Florida Solar Energy Center, Robin Vieira

FSEC Energy Research Center®

The Building America program has been working with home builders for more than a decade using a variety of strategies for bringing fresh air into the homes. Many of these strategies utilize the central air handler fan from the HVAC system to ventilate when the system runs. Controllers can be purchased to force the air to enter for minimum periods of time or to shut off outside air dampers after some period of runtime. EnergyGauge USA, a detailed hourly residential simulation program, has been modified to simulate the various runtime strategies, as well as supply- or exhaust-only ventilation strategies and …

An Overview Of Building America Industrialized Housing Partnership (Baihp) Activities In Hot-Humid Climates, Florida Solar Energy Center, Subrato Chandra

FSEC Energy Research Center®

BAIHP (www.baihp.org ) conducts systems research and technical assistance activities for new housing. Hot-humid climate efforts described here include:

Systems research: NightCool – A hybrid cooling and dehumidification strategy employing radiative cooling and desiccant materials. Interior Duct Systems in Manufactured Houses – Tests are ongoing in an occupied prototype home in Alabama and the FSEC manufactured housing lab. Ventilation and Dehumidification – A new strategy has been developed to hook up a whole-house dehumidifier so that it only runs when the air conditioning compressor is off. Plug Load Reduction – Whole house feedback devices and security system based plug load …

Research Results From A Few Alternate Methods Of Interior Duct Systems In Factory Built Housing Located In The Hot Humid Climate, Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

The U.S. Department of Energy's (DOE) Building America Industrialized Housing Partnership (BAIHP) has collaborated with two of its industry partners to work on a portion of the project that relates to the construction and evaluation of prototype interior duct systems. In 2006, work began on a duct system design that would locate the entire length of duct work within the air and thermal barriers of the envelope. One of these designs incorporated a high-side supply register that connects to the conventional floor duct. The other design utilized a single soffit located within the conditioned space at the marriage line. The …

Assessment Of The Effectiveness And Energy Efficiency Of Humidity Control Approaches In Vacant Florida Homes, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

In a hot and humid climate such as Florida, 'snowbirds' that leave their homes for extended summer periods need guidance on effective and energy efficient methods of humidity control. Experiments were performed in seven residences to evaluate various approaches to humidity control, including providing no mechanical system control. A humidity target was identified to maintain indoor relative humidity (RH) at 65% or lower most of the time. Providing no mechanical conditioning (letting the building 'float') yields relative humidity at 65% or below during hot and sunny weather in some homes, but not during cloudy weather. Setting the AC system thermostat …

Case Study Of An Innovative Hvac System With Integral Dehumidifier, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

In most applications, heating, ventilating, and air conditioning (HVAC) equipment is controlled to maintain an indoor dry-bulb set point temperature. Moisture removal by the HVAC system is considered to be an operational byproduct. During summer months, the operation of the HVAC system is usually sufficient to meet both the sensible and latent cooling loads. However, during other times of the year when sensible loads are reduced, the moisture load can be significantly higher than the available moisture removal capacity of the air conditioning system. This can lead to elevated indoor relative humidity levels and an uncomfortable indoor environment. In many …

Energy Performance Aspects Of A Florida Green Roof, Part 2, Florida Solar Energy Center, Jeffrey Sonne

FSEC Energy Research Center®

This monitored study is an evaluation of summer and winter energy performance aspects of a green roof on a 2-story central Florida university building addition that was completed in 2005. An earlier report on this study was published through the 2006 Symposium on Improving Building Systems in Hot and Humid Climates. This report reviews these earlier results and provides second-summer results which show significant performance improvements for the green roof compared with the first summer results.

Ac System Equipment Specification, Installation And Operational Options For Improved Indoor Humidity Control, Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

High-efficiency home designs have significantly reduced sensible cooling loads, and some building codes and IAQ standards have begun requiring continuous outdoor ventilation air. These trends have led to an increased prevalence of high indoor humidity conditions (Rudd and Henderson 2007). This paper presents a summary of low-cost or no-cost equipment selection and operation options for conventional residential air-conditioning equipment than can result in lower indoor humidity levels. These options should be evaluated and employed to the extent possible prior to considering the added first cost and operating costs of separate dehumidification equipment.

Study On Mechanical Properties Of A356 Alloys Enhanced With Preformed Thixotropic Structure, Shueiwan H. Juang, Shyh-Ming Wu

Journal of Marine Science and Technology–Taiwan

A preformed A356 alloys with thixotropic structure (designated SSM-A356) was systematically studied on mechanical properties in order to establish the database for further investigations in forming and heat treatment. Because of the specific microstructure and characteristics, the heat treatment conditions of SSM-A356 were explored through the observations of microstructure and the measurement of micro-hardness. In the investigation of heat treatment, it was observed that the eutectic silicon was refined and spheroidized which is unlikely for conventional processing. The mechanical testing results showed that the yield and ultimate tensile strength of SSM-A356 were respectively around 115% and 34% greater than those …

Variable-Thickness Boundary Layers For Sliding Mode Control, Chyun-Chau Fuh

Journal of Marine Science and Technology–Taiwan

Sliding mode control is a nonlinear feedback control technique which provides good robustness against modeling uncertainties and external disturbances. However, as the uncertainties or disturbances increase, a greater control input is required, and the control signal may cause an undesirable chattering phenomenon. In general, the further the system trajectory from the origin, the more violent the chattering effect. However, as the trajectory moves closer to the origin, the degree of chattering gradually reduces. As a result, even if an attempt is made to eliminate chattering by introducing a small constant boundary layer around the sliding surface, the chattering phenomenon may …

Investigation Of Heterogeneity Of Fsw Inconel 718 Coupled With Welding Thermal Cycle, Dong Fang Huang

Theses and Dissertations

In order to develop a better understanding of the property, microstructure evolution and thermal history of FSW Inconel 718's, the strain, strain rate and thermal cycles need to be determined. In order to estimate the strain field of a deformed body, a displacement function needs to be determined. A 3D deformation model was developed to determine the displacement coefficients. A rectangular box created in this model deforms following a linear displacement function. Three orthogonal planes cut this deformed box, which leads to three deformed planes. The shape parameters (L, H, θ¹ and θ²) on the three orthogonal planes can be …

The Effect Of Liquid Hot Filling Temperature On Blow-Molded Hdpe Bottle Properties, Benjamin S. Hudson

Theses and Dissertations

The occurrence of deformation in plastic bottles is a common problem in the bottling industry where bottles are blow molded, hot filled at high temperatures and sealed. Plastics have unique properties that make it difficult to predict when and why such changes may occur. The root cause of such deformation is unknown by many bottle producers and recent attempts have been made to minimize the occurrence of such defects. The purpose of this research is to determine which variables involved in the bottle production process influence bottle shape. Earlier variables that were tested included both blow molding resin and total …

Detection Of Voids In Prestressed Concrete Bridges Using Thermal Imaging And Ground-Penetrating Radar, David G. Pollock, Kenneth J. Dupuis, Benjamin Lacour, Karl R. Olsen

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Thermal imaging and ground-penetrating radar was conducted on concrete specimens with simulated air voids. For the thermal imaging inspections, six concrete specimens were constructed during the month of June 2007 to simulate the walls of post-tensioned box girder bridges. The objective was to detect simulated air voids within grouted post-tensioning ducts, thus locating areas where the post-tensioning steel strands are vulnerable to corrosion. The most important deduction taken from these inspections was that PT-ducts and simulated voids were more detectable in the 20 cm (8 in.) thick specimens than in the 30 cm (12 in.) thick specimens. While inspections of …

Hydraulic Actuated Automotive Cooling Systems - Nonlinear Control And Test, John Wagner, M H. Salah, P M. Frick, D M. Dawson

Publications

The replacement of traditional automotive mechanical cooling system components with computer controlled servo-motor driven actuators can improve temperature tracking and reduce parasitic losses. The integration of hydraulic actuators in the engine cooling circuit offers greater power density in a smaller package space when compared with electric actuators. In this paper, a comprehensive nonlinear backstepping robust control technique is developed to regulate the engine coolant temperature by controlling a hydraulic coolant pump and radiator fan. An experimental test bench has been assembled to investigate the hydraulic automotive thermal system performance. Representative numerical and experimental results are presented and discussed. Overall, the …

An Object-Oriented Approach For Modeling And Simulation Of Crack Growth In Cyclically Loaded Structures, D. Cojocaru, Anette M. Karlsson

Mechanical Engineering Faculty Publications

We present an object-oriented modeling frame for simulating crack propagation due to cyclic loadings. Central to the approach is that the crack propagates when a user-defined propagation criterion is fulfilled, i.e., the crack propagation rate is not prescribed but predicted. The approach utilizes the commercial finite element software package ABAQUS and its associated Python based scripting interface. The crack propagation is simulated by a generalized node release technique. If the propagation criteria are satisfied in the end of a cycle, the crack is allowed to propagate. The incremental crack growth is inferred from an iterative investigation of the propagation criteria. …

Generation And Analysis Of Fcg Data Using A Single Specimen And Kmax - ∆K Testing Matrix, Sree Phani Chandar Reddy

Masters Theses

A custom method to generate fatigue crack growth (FCG) data requires testing of multiple specimens at different load ratios. In addition, it includes the application of a load shedding procedure from pre-cracking level to threshold.

In this thesis, a novel method of testing has been investigated that utilizes a single specimen and a testing matrix in terms of K_maxand ∆K values corresponding to predetermined R-ratios for which FCG data, da/dN, are recorded. Automatic K-controlled tests on 2324-T39 Al alloy were conducted using the ∆K increasing and ∆K decreasing procedures while K_maxwas kept constant. Results show that …

Predicting Young’S Modulus Of Nanowires From First-Principles Calculations On Their Surface And Bulk Materials, Guofeng Wang, Xiaodong Li

Faculty Publications

Using the concept of surface stress, we developed a model that is able to predict Young’s modulus of nanowires as a function of nanowire diameters from the calculated properties of their surface and bulk materials. We took both equilibrium strain effect and surface stress effect into consideration to account for the geometric size influence on the elastic properties of nanowires. In this work, we combined first-principles density functional theory calculations of material properties with linear elasticity theory of clamped-end three-point bending. Furthermore, we applied this computational approach to Ag, Au, and ZnOnanowires. For both Ag and Aunanowires, our theoretical predictions …

Translating Terms Of The Functional Basis Into Biologically Meaningful Keywords, Hyunmin Cheong, L. H. Shu, Robert B. Stone, Daniel A. Mcadams

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Biology has long been recognized as an excellent source of analogies and stimuli for engineering design. Previous work focused on the systematic identification of relevant biological analogies by searching for instances of functional keywords in biological information in natural language format. This past work revealed that engineering keywords couldn't always be used to identify the most relevant biological analogies, as the vocabularies between biology and engineering are sufficiently distinct. Therefore, a method of identifying biologically meaningful keywords that correspond to engineering keywords was developed. Here, we apply and refine this method by generating biologically meaningful keywords for the terms of …

Particle Characterization And Concentration Using Aerodynamic Vectoring, Zac Humes

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An experimental demonstration of a new, non-contact particle characterization technique called Aerodynamic Vectoring Particle Sorting (AVPS) is presented. AVPS uses secondary blowing and suction control flows-flows that are a fraction of the jet flow rate-to sharply change the direction of a planar, particle-laden jet. As the jet is vectored, particles present in the flow experience a resultant drag force, dependent upon their size, that balances inertia. Since this balance determines the particle's trajectory, vectoring the flow leads to a separation of particles downstream. This simple, low-pressure-drop sorting technique classifies particles with less risk of damage or contamination than currently available …

Atomistic-Based Finite Element Simulation Of Carbon Nanotubes, Yang Yang

Dissertations

Since first found in the form of multi-walled carbon nanotubes (MWNTs) by Iijima(1991), carbon nanotube (CNT) for its outstanding and unique properties have gained overwhelming attentions from across the spectrum of the science and engineering fields. CNTs are structurally perfect, small size, low density, high stiffness, high strength (Qian et al., 2002), and their electronic properties depend on the particular distortion as well as the initial tube diameter and chirality, ranging from narrow-gap or moderate-gap semiconducting to metallic (Pantano et al., 2004b), which can be utilized in nanoscale sensors and devices. These appealing characteristics provide strong drives for the possible …

Experiments And Models For The Thermal Response Of Railroad Tapered-Roller Bearings, Constantine Tarawneh, Kevin D. Cole, Brent Wilson, Fadi Alnaimat

Mechanical Engineering Faculty Publications

The need to understand and quantify the heat transfer paths within tapered-roller bearings is of great importance in the railroad industry since bearing cup temperature measurement is the primary tool utilized in the removal of distressed bearings from service. Experiments were performed to acquire temperature histories at several locations on a stationary bearing subjected to heat sources imbedded in two rollers. The experimental results were compared to zero- and first-order thermal models to estimate overall heat transfer coefficients from the bearing. The results presented here can be used to explain some of the mechanisms that lead to overheating of tapered-roller …

A Retrospective On Twenty Years Of The Design Theory And Methodology Conference, Jacquelyn K. Stroble, Robert L. Nagel, Kerry R. Poppa, Matt Robert Bohm, Robert B. Stone

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Since its birth from the Design Automation Conference (DAC) and the Association for the Advancement of Artificial Intelligence (AAAI) twenty years ago, the Design Theory and Methodology (DTM) Conference has accepted 769 papers for presentation in a total of 179 tracks. Papers have covered advances in design theory and methods as well as design education, decision making, product development, collaborative endeavors, case studies, information processing, computational methods and industrial applications. through the years tracks have evolved to better define existing research topics and branched to spawn new areas of interest. This paper presents a retrospective of the past twenty years …

Experiments And Models For The Thermal Response Of Railroad Tapered-Roller Bearings, Constantine M. Tarawneh, Kevin D. Cole, Brent M. Wilson, Fadi Alnaimat

Department of Mechanical and Materials Engineering: Faculty Publications

The need to understand and quantify the heat transfer paths within tapered-roller bearings is of great importance in the railroad industry since bearing cup temperature measurement is the primary tool utilized in the removal of distressed bearings from service. Experiments were performed to acquire temperature histories at several locations on a stationary bearing subjected to heat sources imbedded in two rollers. The experimental results were compared to zero- and first-order thermal models to estimate overall heat transfer coefficients from the bearing. The results presented here can be used to explain some of the mechanisms that lead to overheating of tapered-roller …

Determination Of Vibrational Energy Levels And Transition Dipole Moments Of Co2 Molecules By Density Functional Theory, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Efficient Method is Presented to Calculate the Intra-Molecular Potential Energies and Electrical Dipole Moments of CO2 Molecules at the Electronic Ground State by Solving the Kohn-Sham (KS) Equation for a Total of 101 992 Nuclear Configurations. the Projector-Augmented Wave (PAW) Exchange-Correlation Potential Functionals and Plane Wave (PW) Basis Functions Were Used in Solving the KS Equation. the Calculated Intra-Molecular Potential Function Was Then Included in the Pure Vibrational Schrödinger Equation to Determine the Vibrational Energy Eigen Values and Eigen Functions. the Vibrational Wave Functions Combined with the Calculated Dipole Moment Function Were Used to Determine the Transition Dipole Moments. …