Engineering Commons^™

Dynamic Properties Of Railway Track And Its Components : A State-Of-The-Art Review, Sakdirat Kaewunruen, Alexander Remennikov

Faculty of Engineering - Papers (Archive)

Recent findings indicate one of major causes of damages, which is attributed to the resonant behaviours, in a railway track and its components. Basically, when a railway track is excited to generalised dynamic loading, the railway track deforms and then vibrates for certain duration. Dynamic responses of the railway track and its components are the key to evaluate the structural capacity of railway track and its components. If a dynamic loading resonates the railway track’s dynamic responses, its components tend to have the significant damage from excessive dynamic stresses. For example, a rail vibration could lead to defects in rails …

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 …

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 …

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 …

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 …

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 …

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 …

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.

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.

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 …

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 …

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 …

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. …

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 and Presentations

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 …

Edge-Stress Induced Warping Of Graphene Sheets And Nanoribbons, Ashwin Ramasubramaniam, Y. Zhang, C. Reddy, V. Shenoy

Mechanical and Industrial Engineering Faculty Publication Series

We show that edge stresses introduce intrinsic ripples in freestanding graphene sheets even in the absence of any thermal effects. Compressive edge stresses along zigzag and armchair edges of the sheet cause out-of-plane warping to attain several degenerate mode shapes. Based on elastic plate theory, we identify scaling laws for the amplitude and penetration depth of edge ripples as a function of wavelength. We also demonstrate that edge stresses can lead to twisting and scrolling of nanoribbons as seen in experiments. Our results underscore the importance of accounting for edge stresses in thermal theories and electronic structure calculations for freestanding …

Holographic Fabrication Of Photonic Crystals Using Multidimensional Phase Masks, Yuankun Lin, Ahmad Harb, Daniel Rodriguez, Karen Lozano, Di Xu, K. P. Chen

Mechanical Engineering Faculty Publications and Presentations

This paper reports the experimental approaches to the fabrication of two-layer integrated phase masks and the fabrication of photonic crystal templates using the phase mask based on holographic lithography technique. The photonic crystal template is formed by exposing photoresist mixtures to five-beam interference patterns generated through the phase mask. The fabricated phase mask consists of two layers of orthogonally oriented gratings produced in a liquid crystal and photoresist mixture. A polymerization-induced phase separation preserves the grating structure during the exposure. The vertical spatial separation between two layers of gratings produces a phase difference among diffracted laser beams, which enables the …

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 …

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. …

Drilling, Alternative Fuels And Efficiency: Can The United States Wean Itself From Imported Oil?, Florida Solar Energy Center, Philip Fairey

FSEC Energy Research Center®

Perhaps the most daunting challenge the next generation of Americans will face is what President Bush called our "addiction to oil." The challenge is to find the means to provide for our transportation needs in the face of declining world oil production. Perhaps the central question is whether we will export the great wealth of America to foreign countries in payment for oil before we tackle the grand challenge of creating a new transportation future that does not rely completely on oil.

This article presents the historical facts relative to America's oil demand and domestic and world oil production resources. …

Dynamic Responses Of Marine Risers/Pipes Transporting Fluid Subject To Top End Excitations, J. Leklong, S. Chucheepsakul, S. Kaewunruen

Faculty of Engineering - Papers (Archive)

This paper deals with the dynamic responses to top end excitation of marine risers/pipes conveying internal fluid. The marine riser is often used as a flexible link between undersea bore head and subsurface offshore platform. The tidal waves and the changes of sea level consistently excite its top end connected to a floating vessel. In order to carry out the performance-based design of the marine risers, the evaluation of their dynamic responses to top end excitations is imperative. In this study, the marine riser is simulated using twodimensional beam elements. Energy functional of the marine risers conveying fluids is derived …

Micromechanics Model Based On The Nanostructure Of Pfsa Membranes, Ahmet Kusoglu, Michael H. Santare, Anette M. Karlsson, William B. Johnson, Simon Cleghorn

Mechanical Engineering Faculty Publications

A micromechanics model is developed to predict Young’s modulus of perfluorosulfonic acid (PFSA) membranes at various temperatures and water contents. The morphology of PFSA membranes is characterized by a two-phase structure, where hydrophilic clusters expand to hold water molecules during swelling, whereas the hydrophobic polymer network maintains the structural stability. A representative volume element (RVE) is proposed based on the descriptions for the nanostructure of PFSA membranes available in the literature. On the basis of mechanics model, we estimate Young’s modulus in tension of PFSA membranes as a function of water volume fraction for various temperatures. The results show that …

Modified Predator-Prey (Mpp) Algorithm For Single-And Multi-Objective Optimization Problems, Souma Chowdhury

FIU Electronic Theses and Dissertations

The aim of this work is to develop an algorithm that can solve multidisciplinary design optimization problems. In predator-prey algorithm, a relatively small number of predators and a much larger number of prey are randomly placed on a two dimensional lattice with connected ends. The predators are partially or completely biased towards one or more objectives, based on which each predator kills the weakest prey in its neighborhood. A stronger prey created through evolution replaces this prey. In case of constrained problems, the sum o f constraint violations serves as an additional objective.

Modifications of the basic predator-prey algorithm have …

Drop Impact Dynamic Response Study Of Jedec Jesd22-B111 Test Board, Michael Krist, Jianbiao Pan, Andrew Farris, Nicolas Vickers

Industrial and Manufacturing Engineering

Mobile and handheld electronic devices are prone to being dropped. This drop event may result in failure of solder joints inside these devices. The need for RoHS compliant boards coupled with the demand for reliable electronics has resulted in the development of the JEDEC Standard JESD22-B111 to standardize the method of drop testing surface mount electronic components. However, there has been little study on the effects of additional mass on the board and rigidity of the board on drop test reliability. This paper examines the drop impact dynamic responses of the JEDEC JESD22-B111 board. Of interest are the effects of …

Board Level Failure Analysis Of Chip Scale Package Drop Test Assemblies, Nicholas Vickers, Kyle Rauen, Andrew Farris, Jianbiao Pan

Industrial and Manufacturing Engineering

This paper presents the failure analysis results of board level drop tests. In this study, the test vehicle was designed according to the requirements of the Joint Electron Device Engineering Council (JEDEC) drop test board. The test vehicle was assembled with 15 chip scale packages (CSPs) each having 228 daisy-chained 0.5 mm pitch solder joints using Sn-3.0 wt% Ag-0.5 wt% Cu (SAC305) lead free solder. Assemblies were drop tested using three different peak accelerations of 900 G, 1500 G, 2900 G, with 0.7 ms, 0.5 ms, and 0.3 ms pulse durations, respectively. Scanning electron microscopy (SEM) with energy dispersive spectroscopy …

The Effect Of Ultrasonic Frequency On Gold Wire Bondability And Reliability, Jianbiao Pan, Minh-Nhat Le, Cuong Van Pham

Industrial and Manufacturing Engineering

This paper presents a systematic study on the effect of 120KHz ultrasonic frequency on the bondability and reliability of fine pitch gold wire bonding. The study was carried out on a thermosonic ball bonder that is allowed to easily switch between ultrasonic frequency of 60KHz and 120 KHz by changing the ultrasonic transducer and the ultrasonic generator. Bonding parameters were optimized through design of experiment methodology for four different cases: 25.4 μm wire at 60 kHz, 25.4 μm wire at 120 kHz, 17.8 μm wire at 60 kHz, and 17.8 μm wire at 120 kHz. The integrity of wire bonds …

Localised Galvanic Corrosion Processes In Thermal Spray Coated/Cast Aluminium Alloy Systems, David Culliton, Tony Betts, David Kennedy

Conference Papers

Cast Aluminium Alloys, because of the propensity of aluminium to react with impurities and alloying elements, are prone to developing IM impurities during the solidification process. These IM phases can act, in some fluids, as initiation sites for localised corrosion processes, resulting in degradation phenomena, such as pitting. Whilst Thermal Spray coatings can improve the wear resistance of Cast Aluminium Alloys, their corrosion performance may be hampered by the presence of through porosity within the coating.

The present work details some preliminary studies of the localised corrosion processes occurring at the interface area between a Thermal Spray coating and a …

A Plasma Model Combined With An Improved Two-Temperature Equation For Ultrafast Laser Ablation Of Dielectrics, Lan Jiang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

It remains a big challenge to theoretically predict the material removal mechanism in femtosecond laser ablation. To bypass this unresolved problem, many calculations of femtosecond laser ablation of nonmetals have been based on the free electron density distribution without the actual consideration of the phase change mechanism. However, this widely used key assumption needs further theoretical and experimental confirmation. by combining the plasma model and improved two-temperature model developed by the authors, this study focuses on investigating ablation threshold fluence, depth, and shape during femtosecond laser ablation of dielectrics through nonthermal processes (the Coulomb explosion and electrostatic ablation). The predicted …

Three-Dimensional Modeling Of The Plasma Arc In Arc Welding, Gu Xu, J. Hu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Most previous three-dimensional modeling on gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) focuses on the weld pool dynamics and assumes the two-dimensional axisymmetric Gaussian distributions for plasma arc pressure and heat flux. In this article, a three-dimensional plasma arc model is developed, and the distributions of velocity, pressure, temperature, current density, and magnetic field of the plasma arc are calculated by solving the conservation equations of mass, momentum, and energy, as well as part of the Maxwell's equations. This three-dimensional model can be used to study the nonaxisymmetric plasma arc caused by external perturbations such as …

Flush-Mounted Steady-Periodic Heated Film With Application To Shear-Stress Measurement, Kevin D. Cole

Department of Mechanical and Materials Engineering: Faculty Publications

Surface-mounted heated films have been used for fluid-flow measurement for many years. Recently unsteady heating of such surface films has been explored experimentally. In this paper steady-periodic heating of a surface-mounted film is studied analytically. Wall effects and axial heat conduction in the fluid are included. The temperature is found as an exact integral expression constructed from separate Green’s function formulations in the fluid flow and in the solid wall that are matched at the fluid-solid interface. Results for temperature, obtained by quadrature, are reported for several flow speeds and several steady-periodic frequencies. The results show that steady-periodic heating has …