Mechanical Engineering Commons^™

Conjugate Heat Transfer And Average Versus Variable Heat Transfer Coefficients, Tyler James Macbeth

Theses and Dissertations

An average heat transfer coefficient, h_bar, is often used to solve heat transfer problems. It should be understood that this is an approximation and may provide inaccurate results, especially when the temperature field is of interest. The proper method to solve heat transfer problems is with a conjugate approach. However, there seems to be a lack of clear explanations of conjugate heat transfer in literature. The objective of this work is to provide a clear explanation of conjugate heat transfer and to determine the discrepancy in the temperature field when the interface boundary condition is approximated using h_bar compared to …

Analysis Of High Fidelity Turbomachinery Cfd Using Proper Orthogonal Decomposition, Ronald Alex Spencer

Theses and Dissertations

Assessing the impact of inlet flow distortion in turbomachinery is desired early in the design cycle. This thesis introduces and validates the use of methods based on the Proper Orthogonal Decomposition (POD) to analyze clean and 1/rev static pressure distortion simulation results at design and near stall operating condition. The value of POD comes in its ability to efficiently extract both quantitative and qualitative information about dominant spatial flow structures as well as information about temporal fluctuations in flow properties. Observation of the modes allowed qualitative identification of shock waves as well as quantification of their location and range of …

Dynamic Control Of Radiative Surface Properties With Origami-Inspired Design, Rydge B. Mulford, Matthew R. Jones, Brian D. Iverson

Faculty Publications

Thermal management systems for space equipment commonly use static solutions that do not adapt to environmental changes. Dynamic control of radiative surface properties is one way to respond to environmental changes and to increase the capabilities of spacecraft thermal management systems. This paper documents an investigation of the extent to which origami-inspired surfaces may be used to control the apparent absorptivity of a reflective material. Models relating the apparent absorptivity of a radiation shield to time-dependent surface temperatures are presented. Results show that the apparent absorptivity increases with increasing fold density and indicate that origami-inspired designs may be used to …

Development Of A Model And Optimal Control Strategy For The Cal Poly Central Plant And Thermal Energy Storage System, Daniel Douglas Castro

Master's Theses

This thesis develops a calibrated model of the Cal Poly Central Chilled Water Plant with Thermal Energy Storage for use in determining an optimal operating control strategy. The model was developed using a transient systems simulation program (TRNSYS) that includes plant performance and manufacturer data for the primary system components, which are comprised of pumps, chillers, cooling towers, and a thermal energy storage tank. The model is calibrated to the actual measured performance of the plant using the current control strategy as a baseline. By observing and quantifying areas for potential improvement in plant performance under conditions of high campus …

Design And Analysis Of A Lift Assist Walker, Deep P. Shah

Master's Theses

Walkers provided stability to the elderly but cannot assist a person from sitting to standing. The objective of this project is to present the design and analysis of a lift assist walker. This report discusses the design and analysis of a collapsible lift assist walker capable of lifting a patient up to 250 lbs. from seated to standing in under 10 seconds. The designed walker utilized a two stage scissor mechanism with a gas spring assisted embedded linear actuator.

Comprehensive Modeling Of Optimal Paths To Reach Nearly Zero Energy Buildings (Nzebs) For New Constructions In Europe, Florida Solar Energy Center, Delia D'Agostino

FSEC Energy Research Center®

As established by the recast of the European Union (EU) Directive on Energy Performance of Buildings (EPBD), all new buildings have to be nearly zero energy buildings (nZEBs) by the end of 2020. However, reaching this result considering cost-optimality is still an open challenge. Balancing renewable power generation with energy efficiency to reach the nZEB target is a key goal of all EU Member States. We describe results obtained from the modeling of nZEBs for new constructions in Europe using the energy performance software EnergyPlus. The model performs hourly sequential simulations showing how to best achieve nearly zero energy home …

Composite Nanofibers As Advanced Materials For Li-Ion, Li-O2 And Li-S Batteries, Victor Agubra, Luis Zuniga, David Flores, Jahaziel Villarreal, Mataz Alcoutlabi

Mechanical Engineering Faculty Publications

The quest to increase the energy density and improve the cycle life performance of lithium ion batteries (LIBs) and beyond has led to the development of various suitable and alternative materials for energy storage and conversion. The morphology and electrode architecture in advanced battery materials have been re-designed into nanofibers and composite nanofibers. Nanofiber-based separators and electrodes have demonstrated to improve the energy density and cycling performance of LIBs. The improvement in the structure and morphology of nanofibers in LIBs such as LiSi and LiSn, have once again ignited the interest in these Li:M alloy anodes as alternative anode and …

Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie

Faculty Publications

In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom …

Structure Functions, Scaling Exponents And Intermittency In The Wake Of A Wind Turbine Array, Naseem Ali, Aleksandr Sergeyevich Aseyev, Raúl Bayoán Cal

Mechanical and Materials Engineering Faculty Publications and Presentations

Hot-wire measurements obtained in a 3 × 3 wind turbine array boundary layer are utilized to analyze high order structure functions, intermittency effects as well as the probability density functions of velocity increments at different scales within the energy cascade. The intermittency exponent is found to be greater in the far-wake region in comparison with the near-wake. At hub height, the intermittency exponent is found to be null. Extended self-similarity scaling exponents of the second, fourth, and fifth order structure functions remain relatively constant as a function of height in the far-wake; whereas in the near-wake, these are highly affected …

Lattice Flexures: Geometries For Stiffness Reduction Of Blade Flexures, Larry L. Howell, Ezekiel G. Merriam

Faculty Publications

Reducing the motion-direction stiffness of compliant mechanisms reduces their actuation effort and simplifies associated static balancing mechanisms. This work introduces a flexure type called lattice flexures and evaluates some of their fundamental properties. Lattice flexures have a reduced bending stiffness when compared to traditional rectangular-section blade flexures of similar size. The motion-direction bending stiffness of two lattice flexure types, called X-type and V-type, are analytically derived, corroborated with finite element analysis, and validated with measurements of physical prototypes. The lattice flexure has the potential to reduce the bending stiffness of some compliant mechanisms by 60-80%, as demonstrated in devices manufactured …

The Bambow: A Bamboo-Cored Carbon-Fiber Composite Bow, Ezekiel G. Merriam

Student Works

Archery is a sport that has benefited from thousands of years of development. Starting with primitive stick-bows, ancient people found they could propel projectiles larger distances and with more effectiveness than by hand or with other mechanical aids. Over the centuries different cultures adopted and advanced different aspects of the technology, including materials, geometry, and manufacturing methods. In the Mechanical Engineering Department at BYU, Nephi's Steel Bow Competition is held annually to challenge engineering students to test their knowledge of mechanics and materials. As a past participant in this competition, I felt building an advanced composite bow would be an …

Sound Attenuation In Amorphous Silica At Frequencies Near The Boson Peak, Zhi Liang, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We Use Molecular Dynamics Phonon Wave Packet (WP) Simulations to Study Acoustic Propagation and Attenuation in Amorphous Silica (A-SiO₂) at Frequencies Near the Boson Peak (BP) Position and Compare Them with the Results of Equilibrium Molecular Dynamics (EMD) Simulations. the Sound Attenuation Coefficients Obtained from WP Simulations Are Generally Consistent with Those from EMD Predictions and Have Reasonable Agreement with the Existing Experimental Data. Near the BP Position, We Found the Frequency-Dependent Sound Attenuation Coefficients for Longitudinal and Transverse Modes Both Follow the Rayleigh-Scattering Fourth Power Law. above the BP Frequency, However, the Propagating Phonon is Essentially Attenuated …

Phased Retrofits In Existing Homes In Florida Phase I: Shallow And Deep Retrofits (February 2016), Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

The U.S. Department of Energy's Building America research team Building America Partnership for Improved Residential Construction is collaborating with Florida Power & Light (FPL) to conduct a phased residential energy-efficiency retrofit program. This research seeks to establish impacts on annual energy and peak energy reductions from the technologies applied at two levels of retrofit--shallow and deep--with savings levels that approach the Building America program goal of reducing whole-house energy use by 40%.

Implementation Of Space-Time Finite Element Formulation In Elastodynamics, Sidharth Ramesh

Graduate Theses - Mechanical Engineering

Elastodynamics is an academic field that is involved in solving problems related to the field of wave propagation in continuous solid medium. Finite element methods have long been an accepted way of solving elastodynamics problems in the spatial dimension. Considerable thought has been given to ways of implementing finite element discretization in the temporal dimension as well. A particular method of finite element solving called space-time finite element formulation is explored in this thesis, which is a relatively recent technique for discretization in spatial and temporal dimensions. The present thesis explores the implementation of the Space-Time finite element formulation in …

Error-Compensation Method For Inclination Measurement Under The Influence Of The Dynamic Interference, Yanshun Zhang, Yajing Guo, Kui Li, Chaoying Pei, Ming Li

Mechanical and Aerospace Engineering Faculty Research & Creative Works

To deal with the problem of the inclination measurement errors caused by the dynamic motions, such as rotational and accelerated rectilinear components, this paper puts forward an effective inclination measurement scheme and the corresponding error-compensation method based on one accelerometer and two gyroscopes. In addition, the principal prototype of the dynamic inclination measurement apparatus is set up to conduct experiments of turntable rotation test, trolley test, and the turntable sway test at different inclined angles, thus verifying the feasibility of the error-compensation method under the effects of the rotational motion, accelerated rectilinear motion or both motions at the same time. …

Design Live Load Factor Calibration For Michigan Highway Bridges, Christopher D. Eamon, Valid Kamjoo, Kazuhiko Shinki

Civil and Environmental Engineering Faculty Research Publications

In this study, a reliability-based calibration of live load factors for bridge design specific to the State of Michigan was conducted. Two years of high frequency WIM data from 20 representative state-wide sites were analyzed, and load effects were generated for bridge spans from 6 to 122 m (20 to 400 ft), considering simple and continuous moments and shears, as well as single lane and two lane effects. Seventy-five year statistics for maximum live load were then estimated with probabilistic projection. Bridge girders considered for the calibration included composite steel, prestressed concrete, side-by-side and spread box beams, as well as …

Theory, Fabrication, And Experimentation Of Phononic Crystals In Mems At Micro/Nano Scale: Engineering Of Thermal And Rf Phonons To Applications In Thermoelectrics And Microresonators, Seyedhamidreza Alaie

Mechanical Engineering ETDs

Phononic Crystals (PnCs) are novel materials comprised of a periodic structure of inclusions in a matrix. This periodic arrangement creates phononic bandgaps, and modifies phononic bandstructures of a material. Such a property offers promising applications at the micro and nano scales to engineer acoustic filters, high Q-factor resonators, and thermoelectric properties of materials. Studying PnCs at the micro/nano scale requires specific characterization techniques, which rely on Micro Electro Mechanical Structures (MEMS). This work focuses on the study, and characterization of PnCs using MEMS in view of their prospective applications in thermoelectric materials, microresonators and acoustic filters, and also the prospective …

Analysis And Simulation Of Small Scale Microwave Interferometer Experiments On Non-Ideal Explosives, David E. Kittell

Open Access Dissertations

Small scale experiments for non-ideal and homemade explosives (HMEs) were investigated, analyzed, and subsequently modeled in an attempt to develop more predictive capabilities for the threat assessment of improvised explosive devices (IEDs), as well as to provide new analysis capabilities for other investigators in the field. Non-ideal explosives and HMEs are challenging to characterize because of the nearly limitless parameter space (e.g. sample composition, density, particle morphology, etc.) which gives rise to a broad range of explosive sensitivity and performance. Large scale tests, such as rate stick and gap tests, are not feasible for characterizing every HME of interest due …

Inversion Characteristics Of A Buoyant Cylindrical Puck During Oblique Water Impact, Zachary Crawford Smith

Theses and Dissertations

The Apollo Command Module had a tendency to flip over upon impact with the ocean surface after returning from space (9/19 times). In an effort to better characterize the inversion process for future water landing vehicles, experimental results for a simplified buoyant cylindrical puck impacting the water surface are presented. This study focuses on the dependence of inversion upon vertical velocity, horizontal velocity, and the pitch angle of the puck relative to the free surface. High-speed images reveal an asymmetric cavity that forms upon water impact. The asymmetric cavity then collapses, applying a moment, which can be sufficient to invert …

Wind Plant System Engineering Through Optimization Of Layout And Yaw Control, Paul Fleming, Andrew Ning, Pieter Gebraad, Katherine Dykes

Faculty Publications

Recent research has demonstrated exciting potential for wind plant control systems to improve the cost of energy of wind plants. Wind plant controls seek to improve global wind plant performance over control systems in which each turbine optimizes only its individual performance by accounting for the way wind turbines interact through their wakes. Although these technologies can be applied to existing wind plants, it is probable that the maximum benefit would be derived by designing wind plants with these capabilities in mind. In this paper, we use system engineering approaches to perform coupled wind plant controls and position layout optimizations …

Shock Wave Interaction With A Fluid Filled Cylinder Experimental Methods, Praveen Kumar Baba Siddabattuni

Theses

In the recent wars of Iraq and Afghanistan, many soldiers sustained bTBI (blast-induced traumatic brain injury). The blasts are created by extensive use of improvised explosive devices (IED’s). Whether pure blast-shock waves cause TBI or what is the mechanism of injury are not fully known. Research efforts are underway to find answers to these questions.

The primary objective of this project is to understand how the shockwave interacts with a fluid-filled cylinder of different thicknesses. Here, the cylinder is idealized as head and the fluid filled inside it as the brain material. The primary interest here is, how the pure …

Performance Metrics For Depth-Based Signal Separation Using Deep Vertical Line Arrays, Gabriel Paul Kniffin, John Kenneth Boyle, Lisa Zurk, Martin Siderius

Electrical and Computer Engineering Faculty Publications and Presentations

A recent publication by McCargar and Zurk [(2013). J. Acoust. Soc. Am. 133(4), EL320–EL325] introduced a modified Fourier transform-based method for passive source depth estimation using vertical line arrays deployed below the critical depth in the deep ocean. This method utilizes the depth-dependent modulation caused by the interference between the direct and surface-reflected acoustic arrivals, the observation of which is enhanced by propagation through the reliable acoustic path. However, neither the performance of this method nor its limits of applicability have yet been thoroughly investigated. This paper addresses both of these issues; the first by identifying and analyzing the factors …

Relationship Between The Home Energy Score (Hes) And The Home Energy Rating System (Hers), Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

A significant cohort of approximately 2,900 registered home energy ratings using the REM/Rate HERS software tool, as reported to RESNET, are subjected to statistical analysis by the Dillon Group, Inc. The statistical analysis determines the distribution of HES results as a function of home energy efficiency as measured by the minimum standards of the 2009 IECC and by EPA’s ENERGY STAR program.

In addition, a parametric simulation analysis is conducted by the Florida Solar Energy Center using EnergyGauge® USA version 5.0, a RESNET-accredited HERS software tool, to determine the relationship between HES scores and the HERS Index. The parametric analysis …

Multimodal, Biomaterial-Focused Anticoagulation Via Superlow Fouling Zwitterionic Functional Groups Coupled With Anti-Platelet Nitric Oxide Release, Kagya Amoako, Harihara S. Sundaram, Ahmed Suhaib, Shaoyi Jiang, Keith E. Cook

Mechanical and Industrial Engineering Faculty Publications

The functions of anti-fouling, zwitterionic polycarboxybetaine (pCB) and anti-platelet nitric oxide (NO) release replicate key anticoagulant properties of the endothelium. The two approaches, only tested separately thus far, were paired on gas permeable polydimethylsiloxane (PDMS) membranes and evaluated for anti-coagulation. Uncoated PDMS (control) and PDMS coated with pCB were screened for fibrinogen (Fg) fouling followed by platelet adsorption testing to evaluate the effects of coating and/or NO using bioreactors. Bare or coated PDMS membranes separated sheep plasma (108 platelets/ml) and gas flow chambers within the bioreactors. Either 100 or 0 ppm of NO/N2 flowed through the gas chamber for NO …

Life Cycle Assessment And Optimization-Based Decision Analysis Of Construction Waste Recycling For A Leed-Certified University Building, Murat Kucukvar, Gokhan Egilmez, Omer Tatari

Mechanical and Industrial Engineering Faculty Publications

The current waste management literature lacks a comprehensive LCA of the recycling of construction materials that considers both process and supply chain-related impacts as a whole. Furthermore, an optimization-based decision support framework has not been also addressed in any work, which provides a quantifiable understanding about the potential savings and implications associated with recycling of construction materials from a life cycle perspective. The aim of this research is to present a multi-criteria optimization model, which is developed to propose economically-sound and environmentally-benign construction waste management strategies for a LEED-certified university building. First, an economic input-output-based hybrid life cycle assessment model …

Impacts Of Bias Correction Of Wind Forecasts On Hydrodynamic And Wave Model Predictions, Robert J. Weaver, Peyman Taeb, Bryan P. Holman, Steven M. Lazarus, Michael E. Splitt, Atousa Saberi, Jeff Colvin

Ocean Engineering and Marine Sciences Faculty Publications

High-resolution hydrodynamic models are forced by surface wind output from operational met. models. Current suite of operational met. models do not have the spatial resolution needed to resolve the fine scale processes associated with complex estuarine wind-driven circulation nor a detailed land-water mask. Goal: improve forecast wind forcing in most efficient manner as possible

The Relationship Between Intermittent Limit Cycles And Postural Instability Associated With Parkinson’S Disease, James R. Chagdes, Jessica E. Huber, Meredith Saletta, Meghan Darling-White, Arvind Raman, Shirley Rietdyk, Howard N. Zelaznik, Jeffrey M. Haddad

School of Mechanical Engineering Faculty Publications

Background: Many disease-specifc factors such as muscular weakness, increased muscle stiffness, varying postural strategies, and changes in postural refexes have been shown to lead to postural instability and fall risk in people with Parkinson’s disease (PD). Recently, analytical techniques, inspired by the dynamical systems perspective on movement control and coordination, have been used to examine the mechanisms underlying the dynamics of postural declines and the emergence of postural instabilities in people with PD. Methods: A wavelet-based technique was used to identify limit cycle oscillations (LCOs) in the anterior–posterior (AP) postural sway of people with mild PD (n = 10) compared …

Method For Hyper-Polarizing Nuclear Spns At Arbtrary Magnetic Felds, Carlos A. Meriles, Daniela Pagliero, Abdelghani Laraoui

Department of Mechanical and Materials Engineering: Faculty Publications

A method of dynamically polarizing the nuclear spin host of nitrogen-vacancy (NV) centers in diamond is provided. The method uses optical, microwave and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Nitrogen nuclear spin initialization approaching 80% at room temperature is demonstrated both in ensemble and single NV centers without relying on level anti-crossings. This makes the method applicable at arbitrary magnetic fields.

Field Tests Of Two Prestressed Concrete Girder Bridges For Live Load Distribution And Moment Continuity, Christopher D. Eamon, Alaa Chehab, Gustavo Parra-Montesinos

Civil and Environmental Engineering Faculty Research Publications

Two similar bridges constructed with a live load continuous connection were tested for live load distribution and joint continuity. Girder distribution factors (GDFs) were compared to AASHTO equivalent values. For positive moments on all girders as for negative moments on interior girders, results using AASHTO equivalent GDFs were found to be generally conservative. However, for negative moments on exterior girders, test results exceeded AASHTO values, with 2-lane results significantly so. GDF results were verified with a FEA model, which produced similar behavior to the field tests. With respect to joint continuity, it is estimated that a simple span would produce …

Reversible Plastic Events During Oscillatory Deformation Of Amorphous Solids, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The effect of oscillatory shear strain on nonaffine rearrangements of individual particles in a three-dimensional binary glass is investigated using molecular dynamics simulations. The amorphous material is represented by the Kob-Andersen mixture at the temperature well below the glass transition. We find that during periodic shear deformation of the material, some particles undergo reversible nonaffine displacements with amplitudes that are approximately power-law distributed. Our simulations show that particles with large amplitudes of nonaffine displacement exhibit a collective behavior; namely, they tend to aggregate into relatively compact clusters that become comparable with the system size near the yield strain. Along with …