Mechanical Engineering Commons^™

Functional Disaster Resistant Buildings, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

Natural disasters, such as hurricanes, floods, tornados, tsunami and earthquakes, are becoming a greater problem as they destroy lives, homes, businesses and the natural environment. Such disasters can happen with little or no warning, leaving hundreds or even thousands of people without medical services, potable water, sanitation, communications and electrical services for up to several weeks. One proactive strategy to minimize this type of destruction and disruption to lives is the implementation of disaster-resistant buildings that are energy efficient, fortified to the latest codes, and incorporate renewable energy systems. This approach uses the best energy-efficient buildings, fortified to the latest …

Problems And Solutions: Training Disaster Organizations On The Use Of Pv, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

In 1992, the Florida Solar Energy Center (FSEC) and Sandia National Laboratories (SNL) assisted the University of Miami Field Epidemiology Survey Team (FEST) with photovoltaic systems to power temporary medical clinics after Hurricane Andrew struck south Dade County. At that time, it became apparent that there were no educational materials prepared for disaster relief or emergency management personnel on the use of photovoltaic (PV) to supply electrical power in response to a disaster. This need prompted FSEC to create an education program to develop awareness and train organizations on the proper use of PV in disasters. Since then, FSEC has …

Structuring Emperical Methods For Reuse And Efficiency In Product Development Processes, Marshall Edwin Bare

Theses and Dissertations

Product development requires that engineers have the ability to predict product performance. When product performance involves complex physics and natural phenomena, mathematical models are often insufficient to provide accurate predictions. Engineering companies compensate for this deficiency by testing prototypes to obtain empirical data that can be used in place of predictive models. The purpose of this work is to provide techniques and methods for efficient use of empirical methods in product development processes. Empirical methods involve the design and creation of prototype hardware and the testing of that hardware in controlled environments. Empirical methods represent a complete product development sub-cycle …

The Piezoresistive Effect In Microflexures, Gary K. Johns

Theses and Dissertations

The objective of this research is to present a new model for predicting the piezoresistive effect in microflexures experiencing bending stresses. A linear model describing piezoresistivity exists for members in pure tension and compression. Extensions of this model to more complex loading conditions do not match experimental results. An accurate model of piezoresistivity in complex loading conditions would expand the design possibilities of piezoresistive devices. A new model to predict piezoresistive effects in tension, compression, and more complex loading conditions is proposed. The focus of this research is to verify a unidirectional form of this proposed model for microflexures in …

Grid-Connected Photovoltaic System Design Review And Approval, Florida Solar Energy Center, James Dunlop

FSEC Energy Research Center®

This document provides details of operations and procedures for the approval of grid-connected photovoltaic (PV) system designs and documentation conducted by the Florida Solar Energy Center. The principal goal of this process is to help ensure the safety and quality of installed PV systems, and provides an assurance to installers, consumers and financiers that approved designs meet accepted codes and industry practices, and are accompanied by a complete System Manual that meets the minimum requirements outlined in this document.

Executive Summary: Evaluation Of The Impact Of Vacant Home Space Conditioning Strategies On Summer Relative Humidity, Energy, And Peak Load; Phase Ii, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

The Vacant Home Space Conditioning Study was sponsored by Florida Power & Light (FPL) as part of its Conservation R&D Program and carried out by the Florida Solar Energy Center (FSEC). In the US, about one in four retiree "snowbirds" make Florida their destination to escape the northern cold. Snowbird residents number more than 900,000 in Florida during the winter. In some counties of FPL's territory these seasonal residents compose up to 15% of the population (Shih, 1981). This pattern of seasonal occupancy creates a need for space conditioning guidelines for vacant homes to avoid mold problems while minimizing both …

Test Method For Photovoltaic Module Ratings, Florida Solar Energy Center, Kevin Lynn

FSEC Energy Research Center®

This document describes the testing and reporting requirements for certification and labeling of photovoltaic modules (PV) for their power ratings. The test methods and procedures chosen for this purpose are based on consensus standards of relevant committees of the Institute of Electrical and Electronic Engineers (IEEE), the American Society for Testing and Materials (ASTM), or the International Electrotechnical Commission (IEC).

Branch Detonation Of A Pulse Detonation Engine With Flash Vaporized Jp-8, John David Slack

Theses and Dissertations

Pulse Detonation Engines (PDE) operating on liquid hydrocarbon fuels are limited to operating frequencies of 35 Hz due to long ignition times from a low energy ignition sources. This study shows ignition time of JP-8 can be nearly eliminated by igniting a thrust tube using a secondary detonation. A counter flow heat exchanger attached to a thrust tube utilized waste heat from the detonation process to heat JP-8 to supercritical conditions. The fuel flash vaporized when injected into the air stream of the engine. A detonation was produced by a spark in a 5 cm diameter, 1.37 m long tube. …

High-Resolution, Real-Time Three-Dimensional Shape Measurement, Song Zhang, Peisen S. Huang

Song Zhang

We describe a high-resolution, real-time 3-D shape measurement system based on a digital fringe projection and phase-shifting technique. It utilizes a single-chip digital light processing projector to project computer-generated fringe patterns onto the object, and a high-speed CCD camera synchronized with the projector to acquire the fringe images at a frame rate of 120frames∕s. A color CCD camera is also used to capture images for texture mapping. Based on a three-step phase-shifting technique, each frame of the 3-D shape is reconstructed using three consecutive fringe images. Therefore the 3-D data acquisition speed of the system is 40frames∕s. With this system, …

Single-Sided Crash Cushion System, John D. Reid, John R. Rohde, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A single-sided crash attenuation cushion system having an impact head and three stage energy absorption mechanism. The energy absorbing mechanism has a mandrel for deforming thin-walled tubes in a controlled collapse to absorb impact forces from a colliding vehicle. The third stage of the absorption mechanism includes an additional deformable compressible tube between the fixed-object hazard and the thin walled tubes.

A Dynamic Workflow Framework For Mass Customization Using Web Service And Autonomous Agent Technologies, Daniel J. Karpowitz

Theses and Dissertations

Custom software development and maintenance is one of the key expenses associated with developing automated systems for mass customization. This paper presents a method for reducing the risk associated with this expense by developing a flexible environment for determining and executing dynamic workflow paths. Strategies for developing an autonomous agent-based framework and for identifying and creating web services for specific process tasks are presented. The proposed methods are outlined in two different case studies to illustrate the approach for both a generic process with complex workflow paths and a more specific sequential engineering process.

A Torque Based Power Input Model For Friction Stir Welding, Jefferson W. Pew

Theses and Dissertations

For decades models have been developed for predicting the size of the weld nugget and heat affected zones in fusion welded structures. The basis for these models is the welding heat input, which is fairly well understood for most arc welding processes. However, this traditional approach is not as straightforward for Friction Stir Welding (FSW). To date, there is no definitive relationship to quantify the heat input for FSW. An important step to establish a heat input model is to identify how FSW process parameters affect weld power. This study details the relationship between FSW process parameters and torque for …

College Of Engineering Senior Design Competition Fall 2006, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

Large 3-D Deflection And Force Analysis Of Lateral Torsional Buckled Beams, Robert Parley Chase

Theses and Dissertations

This thesis presents research on the force and deflection behavior of beams with rectangular cross-sections undergoing lateral torsional buckling. The large 3-D deflection path of buckling beam tips was closely approximated by circular arcs in two planes. A new chain algorithm element was created from pseudo-rigid-body segments and used in a chain calculation that accurately predicted the force deflection relationship of beams with large 3-D deflections.

Modeling Of The Size Effects On The Behavior Of Metals In Microscale Deformation Processes, Gap-Yong Kim, Jun Ni, Muammer Koc

Gap-Yong Kim

For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/mesoscale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the feature/specimen size effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with three separate experiments obtained from previous research: a simple compression with a round specimen, a simple tension with a round specimen, and a simple tension in …

Hydrodynamic Wave Contributions To Combustion Instability In Rockets, Esam M. T. Abu-Irshaid

Doctoral Dissertations

Experimental measurements suggest that a new source of instability in rocket motors is due to hydrodynamic disturbances. These disturbances, if ignored, could impact our assessment of rocket motor performance. In this work, the corresponding problem of hydrodynamic instability is considered. A mathematical model for these disturbances is carried out by perturbing the continuity and momentum equations. A one dimensional model which represents the wave disturbances in time and space is implemented to quantify the amplification rate, in time or space, and the wave amplitude. The only available measurements of these disturbances arise in cold flow experiments that simulate the gas …

The Thermophysical Roll Of Nanoparticles In Nanofluidic Heat And Mass Transport, Chan Hee Chon

Doctoral Dissertations

Nanofluids are colloids that consist of a base fluid and nanometer sized metallic particles, which serve to improve the heat and mass transport characteristics of nanofluids over those of the base fluid. Many researchers, attracted to the highly enhanced thermal conductivity, have studied nanofluids, and yet have never been able to reveal the basic mechanisms of their characteristic improvements. This present work thus seeks to gain an understanding of the role of nanoparticles in nanofluidic heat and mass transport characteristics through three experimental measurements: 1) thermal conductivity measurement, 2) thermophoretic motion measurement, and 3) evaporation measurement.

Using thermal conductivity, thermophoresis, …

The Stability Analysis Of Linear Dynamical Systems With Time-Delays, Ajeet Ganesh Kamath

Doctoral Dissertations

Time-delay systems, which are also sometimes known as hereditary systems or systems with memory, aftereffects or time-lag, represent a class of infinite-dimensional systems, and are used to describe, among other types of systems, propagation and transport phenomena, population dynamics, economic systems, communication net- works and neural network models. A key method for the stability analysis of time- delay dynamical systems is the Lyapunov’s second method, applied to functional differential equations. Specifically, stability of a given linear time-delay dynamical system is typically shown using a Lyapunov-Krasovskii functional, which involves a quadratic part and an integral part. The quadratic part is usually …

Analysis And Control Of Nonnegative Systems, Jayanthy Ramakrishnan

Doctoral Dissertations

Nonnegative systems are dynamical systems with nonnegative states for random non- negative initial conditions. A subclass of nonnegative systems are compartmental systems characterized by conservation laws.Nonnegative and compartmental systems have widespread applications in biological systems, medical systems, thermodynamic systems, network systems, economic systems, etc.

In this dissertation we have investigated the applications of nonnegative systems in biological and network systems. The specific focus in biological systems has been in the area of pharmacokinetics and we have addressed the consensus problem in network systems. We have specifically focused on the time-delay present in compartmental systems and have investigated the behavior of …

Reliability-Based Optimization Of Fiber-Reinforced Polymer Composite Bridge Deck Panels, Michel D. Thompson, Christopher D. Eamon, Masoud Rais-Rohani

Civil and Environmental Engineering Faculty Research Publications

A reliability-based optimization (RBO) procedure is developed and applied to minimize the weight of eight fiber-reinforced polymer composite bridge deck panel configurations. The method utilizes interlinked finite element, optimization, and reliability analysis procedures to solve the weight minimization problem with a deterministic strength constraint and two probabilistic deflection constraints. Panels are composed of an upper face plate, lower face plate, and a grid of interior stiffeners. Different panel depths and stiffener layouts are considered. Sensitivity analyses are conducted to identify significant design and random variables. Optimization design variables are panel component ply thicknesses while random variables include load and material …

Investigation Of Knock In Gaseous Fuels In The Presence Of Diluents, Roshan Ashok Rodrigues

Masters Theses

Recent energy security and environmental concerns have prompted growing interest into utilization of alternative fuels such as, natural gas and landfill gas. These gaseous fuels contain significant amount of diluents in the fuel composition, such as carbon dioxide, nitrogen, water vapor and other trace gases, which vary by geographical location. Successful engine operation is limited by a phenomenon called "knock", which occurs due to auto-ignition of the end gas ahead of the flame front, and therefore, needs to be investigated with the utilization of these gaseous fuels.

The present contribution discusses the experimental set-up, procedure and results of the investigation …

Titanium Alloyed With Boron, Seshacharyulu Tamirisakandala, Daniel B. Miracle, Raghavan Srinivasan, Jay S. Gunasekera

Mechanical and Materials Engineering Faculty Publications

Small additions of boron to conventional titanium alloys have been found to produce significant changes to the microstructures and associated properties. Grain refinement and improved strength and stiffness are first-order effects, which lead to possibilities for developing novel and affordable processing methodologies and to enhance performance over conventional titanium alloys. In this article, we introduce this new class of titanium alloys and describe unique formability benefits achieved via engineering microstructures.

Solar Dhw Storage Tanks And Systems, Florida Solar Energy Center

FSEC Energy Research Center®

Water is by far the most common storage medium in solar domestic hot water systems. Rock storage is another method of sensible heat storage, but is not generally used in systems that are exclusively DHW. Storage of heat in solutions of phase-changing salts is extremely rare in DHVJ systems and therefore is not discussed.

A Fuzzy Logic Controller For Autonomous Wheeled Vehicles, Mohamed Trabia, Linda Z. Shi, Neil Eugene Hodge

Mechanical Engineering Faculty Research

Autonomous vehicles have potential applications in many fields, such as replacing humans in hazardous environments, conducting military missions, and performing routine tasks for industry. Driving ground vehicles is an area where human performance has proven to be reliable. Drivers typically respond quickly to sudden changes in their environment. While other control techniques may be used to control a vehicle, fuzzy logic has certain advantages in this area; one of them is its ability to incorporate human knowledge and experience, via language, into relationships among the given quantities. Fuzzy logic controllers for autonomous vehicles have been successfully applied to address various …

A Parametric Study Of Water Vapor Condensation In Supersonic Nozzle Flow Fields, Todd Branson Vanpelt

Masters Theses

Combustion driven hypersonic and supersonic wind tunnels are impaired in their flight simulation abilities by the condensation of water vapor introduced into the test stream by the burning byproducts of air and hydrocarbon fuels. The purpose of this study is to evaluate the abilities of a condensation model to predict the beginning axial locations of vapor changing into liquid droplets and study the correlations with initial combustion chamber conditions. A test matrix with different fuels, chamber pressure, and equivalence ratio was applied to the FIRACON model written by Erickson, et al. [7] using the dimensions of the NASA Langley …

A Simple Numerical Method Of Cycle Jumps For Cyclically Loaded Structures, D. Cojocaru, Anette M. Karlsson

Mechanical Engineering Faculty Publications

A method for accelerated numerical simulations of structures subjected to cyclic loading is investigated. Of particular interest is a class of structures where the structural properties evolve with time. The proposed method is based on conducting detailed finite element analysis for a set of cycles to establish a trend line, extrapolating the trend line spanning many cycles, and use the extrapolated state as initial state for additional FEA simulations. This includes a control function that automatically monitors the length of the cycle jump to ensure a realistic solution. We compare the proposed method to a reference calculation, where all incremental …

Multisensor Processing Algorithms For Underwater Dipole Localization And Tracking Using Mems Artificial Lateral-Line Sensors, Saunvit Pandya, Yingchen Yang, Douglas L. Jones, Jonathan Engel, Chang Liu

Mechanical Engineering Faculty Publications and Presentations

An engineered artificial lateral-line system has been recently developed, consisting of a 16-element array of finely spaced MEMS hot-wire flow sensors. This represents a new class of underwater flow sensing instruments and necessitates the development of rapid, efficient, and robust signal processing algorithms. In this paper, we report on the development and implementation of a set of algorithms that assist in the localization and tracking of vibrational dipole sources underwater. Using these algorithms, accurate tracking of the trajectory of a moving dipole source has been demonstrated successfully.

Cooling Of Qps Modular Coils Using Embedded Copper Tubes, Shankar Narasimhaswami

Masters Theses

In an era of insatiable appetite for energy, mankind is challenged to develop a sustainable, safe and clean means of energy production, which would virtually eliminate the existing dependence on fossil fuels. In this regard, Nuclear Fusion technology would give man a quantum leap to mark a near end to the long-term energy concerns and redefine the basis of energy production on earth and elsewhere. This explanation holds rationale on two principal elements 1-Abundant supply of cheap fusion fuel and 2-Surpassingly superior energy production efficiency.

But, as every boon comes with a ‘But’, the criticality of technology is that fusion …

Vision-Based Target Geo-Location Using A Fixed-Wing Miniature Air Vehicle, D. Blake Barber, Joshua D. Redding, Timothy W. Mclain, Randal W. Beard, Clark N. Taylor

Faculty Publications

This paper presents a method for determining the GPS location of a ground-based object when imaged from a fixed-wing miniature air vehicle (MAV). Using the pixel location of the target in an image, with measurements of MAV position and attitude, and camera pose angles, the target is localized in world coordinates. The main contribution of this paper is to present four techniques for reducing the localization error. In particular, we discuss RLS filtering, bias estimation, flight path selection, and wind estimation. The localization method has been implemented and flight tested on BYU’s MAV testbed and experimental results are presented demonstrating …

Field Monitoring And Computer Modeling To Determine Energy And Demand Savings From The Melink Intellihood Exhaust And Make-Up Air Control System At Two Supermarkets, One Restaurant, And One Fast Food Restaurant, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Note: Only the Executive Summary of this proprietary report is available for public download.