Mechanical Engineering Commons^™

Improved Duct Systems Task Report With Stagegate 2 Analysis, Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

The Building America Industrialized Housing Partnership's work with two industry partners, Cavalier Homes and Southern Energy Homes, in constructing and evaluating prototype interior duct systems will be summarized. Issues of energy performance, comfort, DAPIA approval, manufacturability and cost will be addressed. A stage gate 2 analysis will address the current status of project showing that there are still refinements needed to the process of incorporating all of the ducts within the air and thermal boundaries of the envelope.

Orange County Convention Center Energy Analysis And Energy Information System, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

The Orange County Convention Center (OCCC) has the 2nd largest convention facility utilization in the nation. Two primary buildings provide about seven million square feet of conditioned space to approximately 1.5 million visitors per year. In efforts to reduce energy conservation, OCCC began implementing several energy conservation measures beginning in 2005 and continuing over the last 2 years with plans to continue additional efforts in the future. An analysis of monthly chilled water and electricity used by the West and North/South Buildings has been completed in an effort to investigate reductions in energy use resulting from conservation measures. This final …

Incorporating Grain Size Effects In Taylor Crystal Plasticity, Bradley S. Fromm

Theses and Dissertations

A method to incorporate grain size effects into crystal plasticity is presented. The classical Hall-Petch equation inaccurately predicts the macroscopic yield strength for materials with non-equiaxed grains or materials that contain unequal grain size distributions. These deficiencies can be overcome by incorporating both grain size and orientation characteristics into crystal plasticity theory. Homogenization relationships based on a viscoplastic Taylor-like approach are introduced along with a new function, the grain size and orientation distribution function (GSODF). Estimates of the GSODF for high purity α-titanium are recovered through orientation imaging microscopy coupled with the chord length distribution. A comparison between the new …

Bio-Surfaces And Geometric References For A Standardized Biomechanical Design Methodology For Mass Customization, Kimberly A. Jensen

Theses and Dissertations

This dissertation presents a method for the design of customizable products that interface with the human body. The method presented involves first, a consistent method of capturing and representing the human model so that the model can be used with CAx tools and solid modeling techniques. Second, it provides a design methodology based on feature structure planning and assembly modeling that provides a consistent structure to the design process so that it can be reused and parameterized. Third, a strategy for identifying parametric variables that are referenced to the human body is introduced. The core of this method is the …

Reducing Curvature In Complex Tool Paths By Deviating From Cam-Produced Tool Paths Within A Tolerance Band, George Benjamin Naseath

Theses and Dissertations

This thesis develops an algorithm to decrease high-curvature sections in tool paths for complex parts to achieve shorter machining times resulting in higher production rates. In the research sample cases, the algorithm decreased machining times by 1% to 9% for design-induced sections of high curvature and by 16% to 75% for CAM induced ripples using high path tolerances. High-curvature sections in tool paths are caused by complex part geometry, noise, and discontinuities in the model. The curvature is decreased by deviating the tool path within an allowable path tolerance. The feedrate along the tool path is directly related to the …

College Of Engineering Senior Design Competition Fall 2007, 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 …

). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li

Faculty Publications

Relation between the elastic modulus and the diameter (D) of ZnOnanowires was elucidated using a model with the calculated ZnOsurface stresses as input. We predict for ZnOnanowires due to surface stress effect: (1) when D>20nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20nm>D>2nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D<2nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter.

One-Dimensional Radial Flow Turbomachinery Performance Modeling, Robert John Pelton

Theses and Dissertations

The Two-Element In Series (TEIS) and Two-Zone models have been used successfully for over twenty years to model test data for radial flow compressors and pumps. The models can also be used to predict the performance of new machines provided that the model inputs can be accurately specified. Unfortunately, use of the TEIS and Two-Zone models as a predictive tool has been limited because an accurate and broadly applicable method of predicting the modeling parameters, etaA, etaB, chi and d2p does not exist. Empirical models have been developed to predict the TEIS and Two-Zone modeling parameters based on a large …

On The Near Field Mean Flow Structure Of Transverse Jets Issuing Into A Supersonic Freestream, Dean Anthony Dickmann

Mechanical and Aerospace Engineering Dissertations - Archive

The near field mean flow structure of transverse jets issuing from a surface into supersonic crossflow is examined using numerical methods and separation topology. The Navier-Stokes solver Falcon, developed at Lockheed Martin, was used to simulate the interaction between the jet and freestream over a flat plate and a generic missile body. The near field flow structure included a l bow shock upstream of the jet interacting with the approaching boundary layer that forms a pair of horseshoe vortices while another l- structure closer to the jet formed a second pair of horseshoe vortices. As the jet was turned downstream …

Methodologies For Automated Microassembly, Mohammad A. Mayyas

Mechanical and Aerospace Engineering Dissertations - Archive

The development of micromachining technologies has provided wide applications in micro sensing and actuation. However, most of the demonstrated devices are selectively constructed by fabrication processes that are limited to complexity, configuration, dimension, and material variation. The monolithic fabrication has limitations and does not allow the inclusion of multiple components of incompatible processes. Therefore, the construction of 3D microstructures by heterogeneous microassembly is an alternate manufacturing route. In deterministic, monitored or controlled microassembly there has been considerable research in developing, analyzing and applying distributed algorithms for sensor and sensorless based assembly processes. Meso-scale teleoperated work-cells supported by Nano manipulators have …

Thermal Enhancement Of Stacked Dice Replacing Wire Bonds With Through Silicon Vias At Location Of Die Pads, Venkata Chepuri Krishna Teja

Mechanical and Aerospace Engineering Theses - Archive

Through Silicon vias can offer quick time to market of circuits designed in a modular manner and can also be used to customize the product according to the needs of the customers. This gives a way to avoid both excess inventory risks and larger footprints. A through silicon via could be described as, a vertical component through which a backside interconnect for a pair of bonded wafers forming a wafer stack is ultimately cut into a number of stacked dice. Various embodiments have been patented [1, 2] but implementation of these architectures can be inhibited based on thermal, mechanical and …

Numerical Simulation Of Magnetohydrodynamics, Takahiro Sonoda

Mechanical and Aerospace Engineering Theses - Archive

Use of electromagnetic fields has been shown to be an effective way to control the behavior of electrically conducting fluids. Specifically, the modification of the boundary layer profile with electromagnetic fields can yield performance improvements such as reduced drag and improved heat transfer. Though this approach has been demonstrated computationally and experimentally with conducting liquids (i.e. seawater), application to aerodynamic devices operating in air has not seen the same success. Through the use of numerical simulation and eventually optimization, we hope to develop efficient designs that are effective for boundary layer control for low temperature conducting gases (non-thermal plasmas). The …

An Experimental Study On Thermal Bonding Effects Of Pmma Based Micro-Devices Using Hot Embossing, Varun Sood

Mechanical and Aerospace Engineering Theses - Archive

Basic configuration and functioning of various subsystems of a developed HEMM system for thermal bonding are discussed. The bond strength and micro channel geometry degradations dependence on controlled process parameters in thermal bonding using hot embossing has been investigated. The process parameters examined were bonding temperature, bonding or applied load and holding time. Polymeric substrates with different feature dimensions and thickness were embossed and bonded using hot embossing technology. The feature dimensions before and after bonding were examined to assess the geometry changes as functions of the bonding process. This assessment could provide guidance during the design phase of micro-fluidic …

Derivation Of The Dynamics Equations For Receiver Aircraft In Aerial Refueling, Jayme Lynn Waishek

Mechanical and Aerospace Engineering Theses - Archive

This thesis describes the derivation of a new set of nonlinear, 6--DOF equations of motion of a receiver aircraft undergoing an aerial refueling, including the effect of time-varying mass and inertia properties associated with the fuel transfer and the tanker's vortex induced wind effect. Since the center of mass of the receiver is time--varying during the fuel transfer, the equations are written in a reference frame that is geometrically fixed in the aircraft. Due to the fact that aerial refueling simulation and control deal with the position and orientation of the receiver relative to the tanker, the equations of motion …

Stress Distribution And Strength Prediction Of Composite Laminates With Multiple Holes, Brian Esp

Mechanical and Aerospace Engineering Dissertations - Archive

The major purpose of this study was to investigate failure of composite laminates with multiple unloaded holes in close proximity. The least square boundary collocation method for anisotropic materials was utilized to determine the state of stress. The approach utilized collocation on both the internal and external boundaries, making it relatively easy to implement. The method compared favorably to both published and finite element solutions. A failure prediction approach for an infinite, symmetric and balanced laminate, with two holes in close proximity was presented. The baseline material for consideration was IM7/977-3, a carbon fiber/epoxy lamina. The failure prediction method was …

An Analytical And Numerical Model For Design Of Non- Uniformly Powered Silicon Chips Based On Both Thermal And Device Clock Performance, Abhihit D. Kaisare

Mechanical and Aerospace Engineering Dissertations - Archive

Silicon chips continue to grow in capabilities, complexity and performance. Silicon chips typically integrate functional components such as logic and level two (L2) cache memory in their architecture. This functional integration of logic and memory results in improved performance of the chip. However, the integration also introduces a layer of complexity in the thermal design and management of silicon chips. As a direct result of functional integration, the power map on a silicon chip is typically highly non-uniform and the assumption of a uniform heat flux across the chip surface has been shown to be invalid post Pentium II architecture. …

Thermal Stresses Of Composite Beams With Rectangular And Tubular Cross-Sections, Chia-Wei Su

Mechanical and Aerospace Engineering Theses - Archive

Closed-form analytical solutions for laminated composite beams with tubular and rectangular cross-sections are developed for evaluating the thermal induced stresses. The derivations are based on modified lamination theory and parallel axis theorem. The present approach includes variation of ply stiffness along the contour of the cross-section. The interlaminar shear stress of cantilever composite beam with rectangular cross-section under a transverse load is analytically proved to be independent of temperature change in uniform temperature environment. Three-dimensional finite element models for computing thermal stresses of both cross-sections are developed using commercial software package ANSYS 10. The results obtained from analytical solutions give …

Flow Structures In An Enclosed Simplified Full Scale Under-Hood Engine Compartment During Steady State Operation, Chin Hoong Leong

Masters Theses

An experimental study of flow structures in an enclosed simplified full scale under-hood engine compartment will be conducted during steady state operation using whole field velocity measuring technique. 2D Particle Image Velocimetry (PIV) is planned for multiple cross sections in the test volume. Emphasis is given on understanding the flow structures of the 3D under-hood flow using multiple 2D PIV measurements. A recent study conducted on the engine compartment only consists of three 2D PIV measurement cross sections that sufficiently display 2D flow behavior at specific regions. Therefore, a detailed 3D flow mapping in the enclosure on various cross sections …

Experimental Verification Of Source Temperature Modulation Via A Thermal Switch In Thermal Energy Harvesting, Robin Mccarty, D. Monaghan, Kevin P. Hallinan, Brian Sanders

Mechanical and Aerospace Engineering Faculty Publications

This paper provides a description of research seeking to experimentally verify the effectiveness of a thermal switch used in series with TE devices for waste heat recovery for constant and variable source heat input and for variable source thermal capacitance (mass). Using an experimental set-up comprised serially of a fixed heat source, a variable thermal resistance air gap serving as a thermal switch, a thermoelectric device and a heat sink, the time-averaged power output to power input ratios improved up to 15% and 30% respectively for constant and variable heat input in certain design space conditions. The experimental results, as …

Design Of An Active Orthotic Device For Joint Management., Steven Clayton Anderson

Electronic Theses and Dissertations

Existing treatment programs and procedures are incapable of addressing the complications encountered with patients who experience spasticity and hypertonia related joint contractures. Current passive therapy procedures and devices are only capable of managing the extent of joint contractures on patients with chronic and acute onset severe neurological disorders. The project was conceived as a means to develop an active device that is capable of adapting to the state of the joint to mange the extent of contractures and to permit consideration for the prevalence of spastic activity episodes and hypertonia. The project focused on the design of the physical prototype …

A Practical Guideline For Establishing Non-Return Valve Specification And Performance Criteria, Eric W. Dawkins

Masters Theses

The non-return valve has been a standard piece of equipment in the injection molding industry since the reciprocating screw was developed. Most molders understand the role of the non-return valve in the molding process. But few understand the functional problems of the non-return valve. Because of this, the non-return valve has been considered a nuisance item for injection molders.

Wear of the non-return valve is another problem that molders are faced with. The factors contributing toward wear are not entirely understood. Material, temperatures, hours and machine size, etc., all effect the life of a valve. Consequently, most worn valves are …

Modelagem Da Vida De Fadiga E Do Acúmulo De Deformações Permanentes Em Pavimentos Asfálticos Por Meio De Um Modelo De Dano Contínuo, Victor Ferreira Teixeira, Flavio V. Souza, Jorge Barbosa Soares

Department of Mechanical and Materials Engineering: Faculty Publications

: It is known that the conditions of the Brazilian roadways have an enormous impact over the national economy. In face of this problem, there is a need for new methodologies for pavement analyses and design that can more accurately predict pavement distresses. Among the main methods currently used, one can find purely empirical methods and mechanistic-empirical methods which make use of the pavement structure response. The evolution of numerical methods such as the Finite Element Method (FEM) or the Boundary Element Method (BEM) has made the mechanistic-empirical methods more popular for pavement analysis applications. This work shows a mechanistic …

Numerical Study Of Fully Developed Laminar And Turbulent Flow Through Microchannels With Longitudinal Microstructures, Kevin B. Jeffs

Theses and Dissertations

Due to the increase of application in a number of emerging technologies, a growing amount of research has focused on the reduction of drag in microfluidic transport. A novel approach reported in the recent literature is to fabricate micro-ribs and cavities in the channel wall that are then treated with a hydrophobic coating. Such surfaces have been termed super- or ultrahydrophobic and the contact area between the flowing liquid and the solid wall is greatly reduced. Further, due to the scale of the micropatterned structures, the liquid is unable to wet the cavity and a liquid meniscus is formed between …

Undergraduate Research: Experiences From A Three-Year Project, Peter Schuster, Charles Birdsong

Mechanical Engineering

There are significant benefits of research for the involved undergraduate student. These include exposure to advanced topics, introduction to research methods, and direct interaction with faculty and other students. Faculty and institutions benefit as well by the increased interaction with students – fresh eyes in research projects, more energized research groups, and more engaged alumni. However, there are some challenges in designing a research program to work primarily with undergraduates. These include the students’ lack of exposure to advanced topics, short tenure on the project, and potentially lower commitment to the results. There are a number of ways to address …

Designing And Manufacturing Microelectronic Packages For High-Power Light-Emitting Diodes, Brian Wright, Jianbiao Pan, Richard Savage

Industrial and Manufacturing Engineering

A new microelectronic package was designed for a high-power light-emitting diode (LED). The objective was to build a package that enables the LED to operate with currents as high as 2 Amps. An innovative thin-film interface has been developed to electrically connect the cathode of the LED die to a 22AWG Cu wire. This thin-film interface is wirebondable and solderable, and consists of three layers: Au, Ni93/V7, and Si. Four 1 mil Au wirebonds, supporting 2A of maximum current, connect the Au thin-film to the LED die cathode. Sn96Ag4 solder is used for connecting the Ni93/V7 thin-film to the 22AWG …

Trajectory Shaping Of Surface-To-Surface Missile With Terminal Impact Angle Constraint, S. Subchan

Makara Journal of Technology

This paper presents trajectory shaping of a surface-to-surface missile attacking a fixed with terminal impact angle constraint. The missile must hit the target from above, subject to the missile dynamics and path constraints. The problem is reinterpreted using optimal control theory resulting in the formulation of minimum integrated altitude. The formulation entails nonlinear, two-dimensional missile flight dynamics, boundary conditions and path constraints. The generic shape of optimal trajectory is: level flight, climbing, diving; this combination of the three flight phases is called the bunt manoeuvre. The numerical solution of optimal control problem is solved by a direct collocation method. The …

Limiting Maximum Drag Reduction Asymptote For The Moment Coefficient Of An Enclosed Rotating Disk With Fine Spiral Grooves, Budiarso Budiarso, Keizo Watanabe, Satoshi Ogata

Makara Journal of Technology

In this study, the limiting maximum drag reduction asymptote for the moment coefficient of an enclosed rotating disk with fine spiral grooves in turbulent flow region were obtained analytically. Analysis which were based on an assumption for a simple parabolic velocity distribution of turbulent pipe flow to represent relative tangential velocity, was carried out using momentum integral equations of the boundary layer. For a certain K- parameter the moment coefficient results agree well with experimental results for maximum drag reduction in an enclosed rotating disk with fine spiral grooves and drag reduction ratio approximately was 15 %. Additionally, the experimental …

Co2 Absorption From Its Mixture With Ch4 Or N2 Through Hollow Fiber Membrane Contactor Using Water As Solvent, Sutrasno Kartohardjono, Anggara Anggara, Subihi Subihi, Yuliusman Yuliusman

Makara Journal of Technology

CO2 Absorption from Its Mixture with CH4 or N2 through Hollow Fiber Membrane Contactor using Water as Solvent. Hollow fiber membrane contactors have been widely used as gas-liquid contactors recently such as in the CO2 absorption process from gas stream. This research aims to evaluate the effectiveness of hollow fiber membrane contactor to absorb CO2 from its mixture with CH4 or N2 using water through mass transfer and hydrodynamic tests. There are 3 membrane modules used in this research with shell diameter of 1.9 cm, length of 40 cm, outer fiber diameter of 2.7 mm and fiber number in the …

Reverse Link Cdma System Capacity Evaluation For Stratospheric Platform Mobile Communications, Iskandar Iskandar

Makara Journal of Technology

We propose an analysis of reverse link CDMA multispot beam stratospheric platforms (SPF) in this paper. The SPF is currently proposed as a novel wireless technology for the development of the next generation fixed and mobile communications. The geometry of this technology is different from that of the terrestrial but rather similar to the satellite based cellular system. However, evaluation on the CDMA system capacity of this technology has not been much reported. This paper addresses all possible multiple access interference analyses including the effects of channel fading and shadowing in order to evaluate the system capacity. Single SPF and …

The Potency Of Fire And Explosion Hazard On Premium Oil Storage Tank At Depot X 2007, Fatma Lestari, Warid Nurdiansyah

Makara Journal of Technology

The Potency of Fire and Explosion Hazard on Premium Oil Storage Tank at Depot X 2007. Premium oil storage tanks have fire and explosion risk because Premium oil is flammable liquid. Because of that, fire and explosion risk assessment on Premium oil storage tank at Depot X is needed as foundation to fire and explosion risk management, and comply with regulations. Method of this research is Dow’s Fire and Explosion Index. This research indicate that F&EI value for Premium oil storage tank is 118,82. Based on that F&EI value, level of risk at Premium oil storage tank is intermediate risk.