Mechanical Engineering Commons^™

Investigating Solutions To Wind Washing Issues In 2-Story Florida Homes; Phase 1, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Wind washing has been identified as a potentially significant issue regarding energy, demand, comfort, and humidity in some two-story Florida homes. In its most common configuration, wind washing occurs when attic spaces over first-floor portions of the home abut the second story, and the floor cavity of the second story is open to that attic space. Wind blowing into attic vents can push hot attic air into the inter-story floor cavity, bypassing the typical thermal boundaries of the building and introducing considerable heat into the house. Wind washing can also occur when there is little or no attic involved, where …

The Influence Of Branches In The Performance Of Power-Line Communication Systems That Use Mc-Coma With Reed Solomon Coding, Emmanuel Felix

Tanzania Journal of Engineering and Technology (TJET)

Power-line network is proposed as an infrastructure for Information and Communications Technologies (ICTs)
services provision. However, there are a number of factors that contribute greatly to power-line communication performance degradation. These include number of branches that can be added or removed from the power- line network, lengths of the branch lines, loading etc. It has been pointed out that the number of branches is one of the factors that affects power-line performance to a certain extent. In this paper the influence of number of branches on the performance of Broadband Power-line communication (BPLC) that uses MC- CDMA modulation scheme with …

Method Of Transferring Strained Semiconductor Structure, Michael Nastasi

Department of Mechanical and Materials Engineering: Faculty Publications

The transfer of strained semiconductor layers from one substrate to another substrate involves depositing a multilayer structure on a substrate having surface contaminants. An interface that includes the contaminants if formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the deposited multilayer structure is bonded to a second substrate and is separated away at the interface, which results in transferring a multilayer structure from one substrate at least one strained semiconductor layer and at least one strain-induced seed layer. The strain-induced seed layer can be …

Efficient Rotation Algorithms For Texture Evolution, Mark W. Esty

Theses and Dissertations

Texture evolution is a vital component of many computational tools that link structure, properties and processes of polycrystalline materials. By definition, this evolution process involves the manipulation, via rotation, of points in orientation space. The computational requirements of the current methods being used to rotate crystalline orientations are a significant limiting factor in the drive to merge the texture information of materials into the engineering design process. The goal of this research is to find and implement a practical rotation algorithm that can significantly decrease the computation time required to rotate macroscopic and microscopic crystallographic textures. Three possible algorithms are …

Self-Organized Nanolayers Of Organosilane Molecules, Ocelio V. Lima

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

There is a high degree of interest in organic thin films for lightweight, low power, rugged and flexible electronics. Conjugated organic molecules with polycyclic rings are being considered a major enabler of such applications. Due to a surface tension mismatch between the organic molecule with the inorganic support (mainly silicon oxides), molecular packing inside these thin films is often disordered, which suppresses the device performance. There are major efforts focused on modifying the bulk properties, for instance, maximizing orbital overlaps in the solid state, little attention was paid to receive long-range ordered thin films. A novel approach to afford conjugated …

Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung

Journal of Marine Science and Technology–Taiwan

A fuzzy gain scheduling proportional controllers that exhibits the improved performance than the conventional linear fixed gain controller having input saturation is proposed in this paper. We proposed an adaptive anti-windup control system in which the gain of a proportional controller is dynamically tuned by a fuzzy PD system. The methodology employed in the analysis is based on the describing function (DF), which is determined the range of the universal discourse for the output of the fuzzy PD system. Other approaches are the linear quadratic regulator (LQR) method and combined back-calculation and generalized conditioning anti-windup. In this paper, a comparison …

Enhance Diamond Coating Adhesion By Oriented Interlayer Microcracking, Habio Guo, Xingcheng Xiao, Yue Qi, Zhi-Hui Xu, Xiaodong Li

Faculty Publications

In this paper, we report a microcrack toughening mechanism for enhancing the adhesion of diamondcoating. The oriented microcracks were formed within the TiC interlayer to dissipate strain energy and accommodate deformation via the crack opening-closing mechanism, thus enhancing the coating/substrate interfacial toughness. The delamination of diamondcoating was effectively prevented when the parallel microcracks were confined within the interlayer and arrested at interfaces of coating/interlayer/substrate. Density functional theory calculations revealed that the highly anisotropicfracture strength of the TiC phase energetically favors crack initiation and propagation along (100) planes only, which are 54.7° away from the interface. These microcracks are constrained inside …

Robust Stability Bounds For Lur'e System With Parametric Uncertainty, Chyun-Chau Fuh, Pi-Cheng Tung

Journal of Marine Science and Technology–Taiwan

The robust stability of Lur’e system with parametric uncertainty is studied through the Popov-Lyapunov approach. Robust stability bounds of such a system are presented. Since we avoid using norm forms and absolute values, the obtained stability bounds are less conservative. An example demonstrating the feasibility of our method is illustrated

Non-Darcy Flow And Heat Transfer In A Porous Insulation With Infiltration, Hwa-Chong Tien, Kwang-Sheng Chiang

Journal of Marine Science and Technology–Taiwan

This work analyzes non-Darcy flow and heat transfer in a vertical slot filled with a porous matrix. The left and right vertical boundaries of the porous system are maintained at higher and lower temperatures, respectively. The horizontal boundaries are assumed to be impermeable and insulated. The vertical boundaries are either completely impermeable, where free convection is induced, or partially permeable in a way to simulate the wall leakage in the building materials, where both air infiltration and free convection exist. The non-Darcy model, which includes the Brinkman and Forchheimer extensions along with the convection terms, is employed to describe the …

Development Of A Methodology For Numerical Simulation Of A D C Arc Discharge In A Liquid Dielectric, Christopher James Lewis

Theses and Dissertations

The majority of literature regarding the numerical simulation of arc discharges in gaseous environments has used a plasma physics approach. Virtually all simulations treat the discharge as an idealized gaseous plasma, which can be described by temperature, pressure, and electric field. This approach can work well if the media is a shielding gas such as Argon; however, the approach does not work well for processes such as underwater welding, EDM, and underwater discharges used to generate high purity particles. The reason these discharges do not have many extensive simulation efforts as described in the literature is because they occur in …

Energy Dissipation Caused By Asphalt Roadway Gouges For Use In Accident Reconstruction, Charles L. Crosby

Theses and Dissertations

In reconstruction of on-roadway vehicle accidents, roadway surface gouges and the forces and energy attributed to the related vehicle components become important keys to resolving an accurate accident reconstruction. These roadway gouge forces vary depending upon such factors as surface temperature and the velocity and geometry of the gouging mechanism. Accounting for the forces applied to vehicle components and the energy dissipated from such forces can be helpful in accident reconstruction where supporting data exists. This research documents the force necessary to create a given roadway gouge geometry. Controlled pavement gouging tests were performed using roadway surface temperature and gouging …

Discrete Film Cooling In A Rocket With Curved Walls, Jonathan F. Mccall

Theses and Dissertations

This study quantified the effects of discrete wall-based film cooling in a rocket with curved walls. Simulations and experiments showed decreasing with wall radius of curvature, holding jet diameter constant, improves net heat flux reduction (NHFR) and adiabatic effectiveness (η) for 90˚ compound injected cylindrical jets, though η is reduced at the highest curvature. NHFR and η improved further with a high favorable stream-wise pressure gradient (K=2.1x10^-5) at all tested blowing ratios, but were affected little by a high density ratio (DR=1.76) using carbon dioxide as the coolant. Experiments were run at a Reynolds number of 31K and …

Investigation Into Contact Resistance And Damage Of Metal Contacts Used In Rf-Mems Switches, Kevin W. Gilbert

Theses and Dissertations

This research examines the physical and electrical processes involved in lifecycle failure of Microelectromechanical (MEMS) Radio-Frequency (RF) cantilever beam ohmic contact switches. Failures of these switches generally occur at the contact, but complete details of performance of microcontacts are difficult to measure and have not been previously reported. This study investigated the mechanics of microcontact behavior by designing and constructing a novel experimental setup. Three representative contact materials of varying microstructure (Au, Au5%Ru, Au4%V₂O₅) were tested and parameters of contact during cycling were measured. The Au4%V₂O₅, a dispersion strengthened material developed at …

Optical Properties Of Semiconducting Boron Carbide For Neutron Detection Applications, Ravi B. Billa

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Solid state neutron detection devices based on semiconducting boron carbide have the potential for nearly ideal neutron detection effciency for thermal neutrons. The present work is focused on characterizing optical properties of this semiconducting boron carbide material as a step in further development of the material for neutron detection and other applications.

Semiconducting boron carbide films were grown on silicon substrates using plasma enhanced chemical vapor deposition and their optical properties were characterized using variable angle spectroscopic ellipsometry over a wide spectral range, from mid-infrared to vacuum-ultraviolet wavelengths. The effects of deposition substrate temperature and of post-deposition heat treatments on …

College Of Engineering Senior Design Competition Fall 2009, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Each student in his or her senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. 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.

A highlight of the year-long senior design project is the senior design competition. This competition, which usually takes place the week before finals each semester, helps focus the senior students on increasing the quality and potential for commercial application for their design projects.

Judges from local industry evaluate the projects on innovation, commercial …

A Biomechanical Comparison Of Polymethylmethacrylate-Reinforced And Expansive Pedicle Screws In Pedicle-Screw Revisions, Bora Bostan, Irfan Esenkaya, Taner Gunes, Mehmet Erdem, Murat Asci, Mehmet Halidun Kelestemur, Cengiz Sen

Faculty Publications - Mechanical Engineering

Objectives: Different techniques and choices exist for revision of pedicle screws, two of which are pedicle screw combined with cement augmentation and expansive pedicle screw fixation. This biomechanical study was designed to compare the pullout strengths of two different revision techniques. Methods: Fourteen lumbar vertebrae obtained from four calves (mean age 15 months) were divided into two groups equal in number. Monoaxial 6.0-mm pedicle screws were inserted into the right pedicles, and axial pullout testing was performed at a rate of 10 mm/min and failure strengths were recorded. Revision was performed with the same-sized pedicle screws reinforced with polymethyl-methacrylate in …

Nightcool: Nocturnal Radiation Cooling Concept, Long Term Performance Evaluation, Florida Solar Energy Center, John Sherwin

FSEC Energy Research Center®

An experimental evaluation has been conducted on a building-integrated night sky cooling system designed to substantially reduce space cooling needs in homes in North American climates. The system uses a sealed attic covered by a highly conductive metal roof (a roof integrated radiator) which is selectively linked by air flow to the main zone with the attic zone to provide cooling - largely during nighttime hours. Available house mass is used to store sensible cooling. The system's capability for solar dehumidification with minimal electricity input is demonstrated with long-term performance data taken over 2007 - 2009. A year-long study period …

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam …

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam …

Thermocapillary Effects In Driven Dewetting And Self-Assembly Of Pulsed Laser-Irradiated Metallic Films, Mikhail Khenner

Mathematics Faculty Publications

A mathematical model for the evolution of pulsed laser-irradiated, molten metallic films has been developed using the lubrication theory. The heat transfer problem that incorporates the absorbed heat from a single laser beam or the interfering laser beams is solved analytically. Using this temperature field, we derive the 3D long-wave evolution PDE for the film height. To get insights into dynamics of dewetting, we study the 2D version of the evolution equation by means of a linear stability analysis and by numerical simulations. The stabilizing and destabilizing effects of various system parameters, such as the reflectivity, the peak laser beam …

Thermodynamically Consistent Large Deformation Constitutive Model For Glassy Polymers, Ashwani Kumar Goel

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Polycarbonate(PC), like most glassy polymers when undergoing large deformations exhibits a very complex thermo-mechanical response. We look at PC as a model glassy polymer and examine its response to changes in loading rate, loading direction and temperature. We show that plastic flow in compression is accompanied by a change in the elastic response of PC from isotropic to anisotropic. This provides the necessity to introduce a new modeling method that can capture these changes. A finite deformation plasticity like thermodynamically consistent model is developed to capture this and the observed rate and temperature dependence. For this modeling method, we need …

Boundary Layer Data System (Blds) Heating System, John Hauge, Drew Hutcheson, Paul Scott

Mechanical Engineering

The boundary layer data system (BLDS) is the result of a collaborative effort between Dr. Westphal, a researcher and instructor at Cal Poly, and Northrop Grumman. The BLDS is capable of measuring the boundary layer profile and characteristics of flow over aerodynamic surfaces and is intended for high altitude, high speed use. The instruments inside the BLDS malfunction at the low temperatures present when operating in flight at altitudes above 30,000 ft. To solve this problem, analysis was done on the existing BLDS which determined the heating requirements, around 50 watts, needed to keep the internal temperature within the rated …

Air Cooling For Aecm Module, Final Project Report, Kevin Whipp, Abraham Bruno Caulk

Mechanical Engineering

Advancements in electronics have created the need for improved cooling standards. The AECM standard, created to replace the antiquated ARINC 600 specification for aircraft, draws inspiration from a cooling specification known as VITA 48.2. The ARINC standard is in early stages of development and this project researches the feasibility of using air as a convective fluid instead of a liquid, the fluid used in the VITA specification.

A performance factor calculated from the ratio of the heat dissipated by convective heat exchanger plates over the power used to cause forced convective flow over said plates helps to quantify the effectiveness …

Indirect Pipe Pressure Measurement, Clayde Barkley, Mikel Betts, Anthony Olay

Mechanical Engineering

Statement of Confidentiality The complete senior project report was submitted to the project advisor and sponsor. The results of this project are of a confidential nature and will not be published at this time.

Formula Sae Interchangeable Independent Rear Suspension Design, Mike Mccune, Daniel Nunes, Mike Patton, Courtney Richardson, Evan Sparer

Mechanical Engineering

The Suspension Solutions design team has completely designed built and tested an independent rear suspension system for the 2008 FSAE car. The car currently features a solid rear axle, and the task of converting it to incorporate an interchangeable rear suspension has been undertaken in order to quantify the advantages and disadvantages of each design philosophy. The car has been properly tested with both the solid axle and independent rear suspension side-by-side, however more testing is suggested. After pushing both setups to their limits on a 50ft diameter skid pad, the test results were quantified, and a final comparison between …

Design, Reconstruction And Evaluation Of A Dynamometer For Quarter Scale, Samuel Sanchez

BioResource and Agricultural Engineering

This project discusses the design, reconstruction, and evaluation of a dynamometer. A new test stand for the Quarter Scale team would improve the testing of the engines and the Continuously Variable Transmission (CVT). All the readings will be done electronically in order to provide the most accurate data collection. The dynamometer will be a closed hydraulic system for ease of use. This system will be able to test all of Quarter Scale engines. The data collected will be used to determine which engines are in the best condition, and which may need to be fixed. With the new design, the …

The Part Count Tool (Pact) For Concept Selection, Tarang Parashar, Katie Grantham Lough, Robert B. Stone

Engineering Management and Systems Engineering Faculty Research & Creative Works

This paper presents a part count tool that automates the consideration of manufacturing cost during the conceptual design phase by predicting part count for a particular product concept. with an approximate number of parts per product in the conceptual design phase, the designer can estimate the cost associated with the product. on the basis of the cost, the designer can make changes according to budget requirements. the part count tool will also aid in ranking the design concepts by number of components for a product. This tool utilizes existing automated concept generation algorithms to generate the design concepts. It extracts …

Laboratory Generation And Physics Of Propagation Of Solitary Waves And Water Surface Depressions, Siamak Malek Mohammadi

All Dissertations

Solitary waves and water surface depressions are generated using a piston-type wavemaker. Different aspects of their propagation including profile evolution, establishment rate, stability, and celerity are examined experimentally.
Traditionally, solitary waves are generated in laboratory set-ups using a methodology developed by Goring (1979) that considers a wave of permanent form during the generation process. A New methodology for generation of solitary waves using piston-type wavemakers is proposed by considering the evolving nature of the wave during generation phase. The capability of the New methodology in generation of solitary waves is assessed by conducting a series of laboratory experiments in water …

Gender Dimorphic Acl Strain In Response To Combined Dynamic 3d Knee Joint Loading: Implications For Acl Injury Risk, Kiyonori Mizuno, Jack T. Andrish, Antonie J. Van Den Bogert, Scott G. Mclean

Mechanical Engineering Faculty Publications

While gender-based differences in knee joint anatomies/laxities are well documented, the potential for them to precipitate gender-dimorphic ACL loading and resultant injury risk has not been considered. To this end, we generated gender-specific models of ACL strain as a function of any six degrees of freedom (6DOF) knee joint load state via a combined cadaveric and analytical approach. Continuously varying joint forces and torques were applied to five male and five female cadaveric specimens and recorded along with synchronous knee flexion and ACL strain data. All data (~10,000 samples) were submitted to specimen-specific regression analyses, affording ACL strain predictions as …

Study Of Take-Up Velocity In Enhancing Tensile Properties Of Aligned Electrospun Nylon 6 Fibers, Johnny F. Najem

Mechanical Engineering Faculty Research

The variation of both the tensile properties and thermal properties of aligned electrospun fibers with the take-up velocity (TUV) of disc collector has not been widely investigated due to the difficulty of handling aligned nanofibers and measuring low loads. In this thesis, 25% of nylon 6 was dissolved in formic acid and then electrospun into fibers and the fibers were aligned using a rotating disc collector. We evaluated the tensile and thermal properties, average fiber diameter, crystallinity, crystalline morphology, molecular and crystalline orientation of aligned electrospun nylon 6 nanofibers as a function of TUV based on a disc collector. It …