Mechanical Engineering Commons^™

Low Cost Flow Sensing For Field Sprayers, Yue Zhang

Theses and Dissertations--Biosystems and Agricultural Engineering

Precisely measuring the flow rate in sprayers is a key technology to precision agriculture. With the development of advanced technologies, the demand for the ability to measure flow rate of individual nozzle has become more important and urgent.

This paper investigates the possibility of developing a low-cost flow rate measurement technique. The technique is based on analyzing the acoustic signal from a microphone placed near the nozzle tip. A comparison between acoustic signal and vibration signal was made to study the relations between them. Then several possible locations of the microphone for measuring flow rate were tested and compared, and …

Filtered-Dynamic-Inversion Control For Fixed-Wing Unmanned Aerial Systems, Jon Mullen

Theses and Dissertations--Mechanical and Aerospace Engineering

Instrumented umanned aerial vehicles represent a new way of measuring turbulence in the atmospheric boundary layer. However, autonomous measurements require control methods with disturbance-rejection and altitude command-following capabilities. Filtered dynamic inversion is a control method with desirable disturbance-rejection and command-following properties, and this controller requires limited model information. We implement filtered dynamic inversion as the pitch controller in an altitude-hold autopilot. We design and numerically simulate the continuous-time and discrete-time filtered-dynamic-inversion controllers with anti-windup on a nonlinear aircraft model. Finally, we present results from a flight experiment comparing the filtered-dynamic-inversion controller to a classical proportional-integral controller. The experimental results show …

Experimental Studies On The Determination Of Acoustic Bulk Material Properties And Transfer Impedance, Wanlu Li

Theses and Dissertations--Mechanical and Aerospace Engineering

Soft trim absorbing parts (i.e., headliners, backwalls, side panels, etc.) are normally comprised of different layers including films, adhesives, foams and fibers. Several approaches to determine the complex wavenumber and characteristic impedance for porous sound absorbing materials are surveyed and the advantages and disadvantages of each approach are discussed. It is concluded that the recently documented three-point method produces the smoothest results. It is also shown that measurement of the flow resistance and the use of empirical equations is sufficient for many common materials. Following this, the transfer impedance of covers, adhesives, and densified layers are measured using an impedance …

Optimization Of Wind Fence Enclosures For Infrasonic Wind Noise Reduction, Johnpaul Russell Abbott

Electronic Theses and Dissertations

A large porous wind barrier enclosure has been built and tested to optimize wind noise reduction at infrasonic frequencies between 0.01-10 Hz in order to develop a technology that is simple, cost effective, and improves upon the limitations of pipe and porous hose arrays. The effects of varying the fence's porosity, modifying its top condition and bottom gap, doubling the height and diameter, and adding a secondary wind barrier were investigated. A simple mathematical model which estimates the wind noise measured at the center of the enclosure was derived based on the measured turbulence and velocity profiles measure outside the …

Visualizing Interior And Exterior Jet Aircraft Noise, Manmohan Singh Moondra

Wayne State University Dissertations

In today's competitive aerospace industry, the quest for quiet has drawn significant attention to both the interior and exterior design of an airplane. Understanding the noise generation mechanisms of a jet aircraft is a crucial first step toward developing the most cost-effective noise and vibrations abatement methods. In this investigation, the Helmholtz Equation Least Squares (HELS) based nearfield acoustic holography will be used to understand noise transmission caused by jet engine and turbulence into the fuselage of a jet aircraft cruising at 30,000 ft.

Modern propulsive jet engines produce exterior noise sources with a high amplitude noise field and complicated …

Neuromodulation Based Control Of Autonomous Robots On A Cloud Computing Platform, Cameron Muhammad

College of Graduate Studies: Theses & Dissertations

In recent years, the advancement of neurobiologically plausible models and computer networking has resulted in new ways of implementing control systems on robotic platforms. The work presents a control approach based on vertebrate neuromodulation and its implementation on autonomous robots in the open-source, open-access environment of robot operating system (ROS). A spiking neural network (SNN) is used to model the neuromodulatory function for generating context based behavioral responses of the robots to sensory input signals. The neural network incorporates three types of neurons- cholinergic and noradrenergic (ACh/NE) neurons for attention focusing and action selection, dopaminergic (DA) neurons for rewards- and …

Effects Of Time Varying Background Noise Conditions On Human Perception And Performance, Andrew H. Hathaway

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

This thesis was designed to study the effects of changing noise conditions on human perception and performance. In two phases, participants were exposed to a number of noise conditions and their performance on an arithmetic task involving short-term memory was monitored and their subjective perception of noise conditions was collected via questionnaires.

In the first phase, participants were tested while being subjected to RC-29(H) and RC-47(RV) conditions created by broadband noise fluctuating on different time intervals, resembling the changing noise conditions potentially found in modern HVAC systems. These intervals varied from two minutes to ten minutes. Results show a significant …

Ultrasonic Propagation And Scattering In Pearlitic Steel, Hualong Du

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

Diffuse ultrasonic backscatter measurements have been especially useful for extracting microstructural information and for improving flaw detection in materials. In this dissertation, this approach is applied to inspection of railroad wheels. To improve the wear resistance, the tread surfaces of railroad wheels are usually quenched with water to increase the hardness. The pearlite phase of iron, characterized by alternating ferrite and cementite phases, is created by the quenching and the lamellar spacing within grains increases progressively from the quenched tread surface to deeper locations due to the non-uniform cooling rate. The quench depth is an important parameter governing the wheel …

Visualizing Mechanics: Improving Student Learning Through Video Demonstrations, Blake A. Wetherton, Olumide A. Awofeso, Carolyn E. Creighton, Adam F. Potrzebowski, Charles M. Krousgrill, Jeffrey F. Rhoads

The Summer Undergraduate Research Fellowship (SURF) Symposium

The Purdue Mechanics Freeform Classroom (PMFC) is a project that seeks to reform engineering mechanics education by integrating content and technology; enhancing communication between students, their peers, and instructors; accommodating a broader range of learning styles; and facilitating greater depths of understanding. In an attempt to increase the PMFC’s efficacy, a series of demonstration videos has been produced. As demonstrated by the popularity and pervasiveness of websites such as YouTube, short videos have the potential to captivate audiences. As such, these videos have incredible promise in educational contexts. In the PMFC series of videos, entitled Visualizing Mechanics, each imitates the …

Effect Of Compression On The Transmission Loss Of Porous Material, Yingchao Yang, J Stuart Bolton

The Summer Undergraduate Research Fellowship (SURF) Symposium

Porous materials are commonly applied in sound absorption in different places. Transmission loss, one of the vital parameters determining the performance of the material, will change when the material is compressed. Usually the compression that might affect the properties to the greatest extent are normal compression and the deformation can be simplified as 1D compression model. In order to verify the prediction, some formulas taking several parameters (porosity, tortuosity, flow resistivity and characteristic lengths) into account are applied and also the Johnson et al’s model of limp structure. Dynamic density of limp model and bulk modulus are thus obtained and …

Semi-Active Structural Control Of A 2-Story Shear Building, Alana K. Wilbee, Shirley Dyke

The Summer Undergraduate Research Fellowship (SURF) Symposium

With continuing urban development across the world, it is becoming ever more important to provide increased structural safety against events such as earthquakes and strong winds. The field of structural control has recently been growing to meet these challenges through the use of semi-active control methods, such as the Magnetorheological (MR) Damper. However, due to the non-linearity of the device, the knowledge base surrounding the MR Damper and its various control algorithms still needs to be strengthened before large-scale implementation of this control method can occur. To address these issues, this study will examine a two story benchmark structure using …

Improvement On Cylinder-To-Cylinder Variation In Pcci Engines Using Variable Start Of Injection And Exhaust Valve Closing Timings, Aðalsteinn Axelsson, Greg Shaver

The Summer Undergraduate Research Fellowship (SURF) Symposium

Premixed charge compression ignition (PCCI) is widely considered to be a possible method of meeting increasingly strict emissions regulations in internal combustion engines. PCCI can reduce harmful emissions substantially and at the same time increase efficiency relative to conventional combustion modes. Because of the nature of PCCI, changes in in-cylinder conditions have a greater impact than in conventional diesel engines. Therefore cylinder to cylinder variations are amplified which leads to problems such as misfire and decreased efficiency in cylinders with increased ignition delay and lower apparent heat release rate (AHRR) amplitudes. Two possible methods to counteract this effect in diesel …

The Stability And Control Of The Single Track Vehicles, Shyngys Karimov, Martin Corless

The Summer Undergraduate Research Fellowship (SURF) Symposium

Bicycles, motorcycles and scooters are all examples of the single track vehicles. The dynamics of the single track vehicle involve many degrees of freedom and various modes which govern its performance, making a complicated and interesting research topic. Motorcycle in motion can roll, yaw, and steer about the steering axis. It has three main modes which determine the motion and stability of it, they are weave, capsize, and wobble. The motorcycle performance is limited by the behavior of its modes, and if even one of the modes becomes unstable, the vehicle will roll over, and crash. The goal of this …

Code Optimization For Phase Field Method, Sergio Andres Monsalve, Marisol Koslowski

The Summer Undergraduate Research Fellowship (SURF) Symposium

The Phase field model method for studying grain dislocation at atomic level after applying an external force to the materials being tested, enables simulate the behavior of different materials after applying stress. With the appropriate numerical method the simulation could change drastically the complexity of the algorithm. Finding the most accurate and stable numerical method for the phase field model give us a considerable improving in the performance of the code used to simulate the phase field dynamic dislocation in larger and more complex simulations can be performed. We made an statistic comparison between the different methods, comparing stability and …

Numerical Simulation Model On Irreversibility Of Shock-Wave Process, Longhao Huang

Master's Theses (2009 -)

The objective of this research is to develop a better understanding of the irreversibilities associated with the shock compaction of matter, especially as a result of impact. Due to complex shock processes, experimentation alone cannot fix the material state, since properties such as internal energy, entropy as well as the shock process are not measurable. Thus, in addition to experimentation, analytical and numerical methods are also used to completely characterize the shock process, although they are restricted by underlying constitutive assumptions. Instead of using artificial irreversibility, such as artificial viscosity to simplify and stabilize the numeric shock model, this work …

Propagation Of Sound In The Vicinity Of Rigid Porous Interfaces, Hongdan Tao

Open Access Dissertations

Propagation of sound in the vicinity of rigid porous interfaces is investigated systematically to facilitate the acoustical characterization of sound absorption materials for noise reduction applications. Various rigid porous interfaces are considered: (1) a semi-infinite porous layer; (2) a porous hard-backed surface; and (3) a porous impedance-backed layer. A closed-form solution and numerical methods are derived with respect to each rigid porous interface condition.

A modified saddle-point method is exploited to investigate the sound field emanating from a monopole source above and below a rigid porous interface. The solutions can be expressed in a form that resembles the classical Weyl-Van …

Mechanisms Of Microstructure Formation Under The Influence Of Ultrasonic Vibrations, Milan Rakita

Open Access Dissertations

Positive effects of ultrasound on crystallization have been known for almost 90 years. Application of ultrasound has been very successful in many industries, most notably in chemistry, creating a new branch of science - sonochemistry. However, ultrasonication has not found wide commercial application in the solidification processing. The reason for that is the complexity of underlying phenomena and the lack of predicting models which correlate processing parameters with the properties of a product. The purpose of this study is to give some contribution toward better understanding of mechanisms that lead to changes in the solidifying microstructure. It has been found …

Qualitative Methods Used To Develop And Characterize The Circulation Control System On Cal Poly's Amelia, Eric N. Paciano

Master's Theses

The circulation control system onboard Cal Poly's Advanced Model for Extreme Lift and Improved Aeroacoustics was a critical component of a highly complex wind tunnel model produced in order to fulfill the requirements of a NASA Research Announcement awarded to David Marshall of the Aerospace Engineering Department. The model was based on a next generation, 150 passenger, regional, cruise efficient, short take-off and landing concept aircraft that achieved high lift through circulation control wings and over-the-wing mounted engines. The wind tunnel model was 10-ft in span, used turbine propulsion simulators, and had a functioning circulation control system driven from tunnel …

Analysis Of Connecting Rod Bearing Design Trends Using A Mode-Based Elastohydrodynamic Lubrication Model, Travis M. Blais

Theses

Available design trends for big end connecting rod bearings utilize widely adopted rapid methods for prediction of minimum film thickness due to their superior speed and ease of use. However, they impose unrealistic assumptions such as surface rigidity, which could compromise the accuracy of results. The significance of structural elasticity and updated models was investigated using a mode based elastohydrodynamic lubrication model which includes body forces, mass conserving cavitation, and surface roughness. Eight physical connecting rods were modeled using finite element methods and simulated over a variety of conditions, varying engine speed, bearing clearance, and oil viscosity. The results show …

Characterization Of The Drilling Via The Vibration Augmenter Of Rotary-Drills And Sound Signal Processing Of Impacted Pipe As A Potential Water Height Assessment Tool, Nicholas Morris

STAR Program Research Presentations

The focus of the internship has been on two topics: a) Characterize the drilling performance of a novel percussive augmenter – this drill was developed by the JPL’s Advanced Technologies Group and its performance was characterized; and b) Examine the feasibility of striking a pipe as a means of assessing the water height inside the pipe. The purpose of this investigation is to examine the possibility of using a simple method of applying impacts to a pipe wall and determining the water height from the sonic characteristic differences including damping, resonance frequencies, etc. Due to multiple variables that are relevant …

Investigation Of Sound Transmission Through An Open Window Into A Room, Caleb F. Sieck

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

In recent decades, noise levels in cities and the associated annoyance and health consequences have become regular topics of discussion. As a result, the assessment of environmental noise transmitting into buildings has received much attention. Current models of sound transmission through open windows have either neglected their thickness or the presence of a room behind on one side. The objectives of the present work were to (1) develop an accurate analytical model of sound transmission through an open window of finite thickness into a room, (2) verify the analytical model using a finite element model and experimental measurements, and (3) …

Dynamic Modeling Of A Belt Driven Electromechanical Xy Plotter Cutter, Joseph V. Prisco

Master's Theses (2009 -)

Current industrial XY plotter cutters that use a belt driven gantry for the X motion and media feed for the Y motion sometimes have performance issues in cutting out high quality shapes. Mathematical models for these plotter cutters are not publicly available and thus the parameters critical to cut quality are not well understood. This thesis develops a dynamic, electromechanical model for the gantry arm and media feed using first principles and a non-linear friction model. These models are independently simulated and experimentally verified. In order to verify the effectiveness of the individual models, they are combined with a control …

Rating Low Levels Of Ambient Noise In Performing Arts Facilities, Lily M. Wang, Brent A. Kraay

Durham School of Architectural Engineering and Construction: Faculty Publications

Previous studies have indicated that common indoor noise rating metrics, such as Noise Criteria NC and Room Criteria RC, do not best correlate to human perceptions of annoyance and distraction in typical office environments. Based on investigations conducted at the University of Nebraska using noise levels between 30 – 60 dBA, the author has proposed that an effective indoor noise rating method should begin with a rating of level (either dBA or sones), then an assessment of spectral quality, tones, and fluctuations. How well would such a system work at very low levels of ambient noise, though, as found in …

Quantifying The Just Noticeable Difference Of Reverberation Time With Band-Limited Noise Centered Around 1000 Hz Using A Transformed Up-Down Adaptive Method, Matthew G. Blevins, Adam T. Buck, Zhao Peng, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This study seeks to quantify the just noticeable difference (JND) of reverberation time (RT) using band-limited noise. ISO 3382-1 lists the JND of reverberation metrics at 5% based on work by Seraphim (1958). However, others have found the JND of RT to be higher from 6% to 39%. Many of these studies utilized band-limited stimuli, e.g. speech, music motifs and bandlimited noise. A previous study by the authors conducted on 30 subjects using white noise demonstrated a JND of RT at 22%. To further verify these results and investigate potential upward frequency masking, the present study was conducted following the …

Effects Of Background Noise Alternating Between Two Levels At Varying Time Intervals On Human Perception And Performance, Andrew Hathaway, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This research experiment aims to better quantify human perception and performance under increased background noise levels of varying intervals. Twenty-seven participants were tested over five 30 minute sessions where they were subjected to RC-29(H) and RC-47(RV) conditions created by broadband noise fluctuating on different time intervals. These intervals varied from two minutes to ten minutes, simulating the conditions of a noisy HVAC system turning on and off. The performance results of an arithmetic test dealing with short-term memory and a subjective questionnaire will be presented and compared to a similar test using broadband noise bursts and correlated to noise metrics …

Effects Of Reverberation And Noise On Speech Comprehension By Native And Non-Native English-Speaking Listeners, Zhao Peng, Lily M. Wang, Siu Kit Lau, Adam M. Steinbach

Durham School of Architectural Engineering and Construction: Faculty Publications

Previous studies have demonstrated the negative impact of adverse signal-to-noise-ratios on non-native English-speaking listeners' performance on speech recognition using recall tasks, as well as implied that comprehension skills were more impaired than recognition skills under reverberation and noise. The authors have themselves previously conducted a pilot study on three native and three non-native Englishspeaking listeners to examine the effects of reverberation and noise using speech comprehension tasks. Those results suggested that speech comprehension performance is worse under longer reverberation times (RT), and that a longer RT is more detrimental to speech comprehension by non-native listeners than native listeners. This paper …

High Temperature Filter Test Unit Upgrades, Blair Frandeen, Will Schill, Erick Shewmaker, Joshua Turgeon

Mechanical Engineering

The purpose of this project was to improve the existing High Temperature Filter Test Unit (HTTU) by optimizing performance and adding new features. These features include viewing ports and a camera system for observation of tests, a leak detection system, and a flame impingement system. Additional considerations included improving the current operation of the HTTU by reducing test time and energy loss. The HTTU is designed to test High Efficiency Particulate Air (HEPA) filters at temperatures up to 1300 ˚F, creating conditions which simulate a fire in a chemical processing facility. The HTTU was originally built as a Cal Poly …

Autonomous Collision Avoidance, Thomas Stevens, Elliot Carlson, Ian Painter

Mechanical Engineering

A steering controlled, autonomous collision avoidance system has been developed by California Polytechnic State University. This system represents a step in the direction of fully autonomous driving, while allowing the driver to maintain control of the vehicle during normal driving conditions. In the case of an imminent collision, the system removes control of the vehicle from the user and autonomously steers around the obstacles. The final system is able to avoid two static obstacles with a 95% pass rate and one moving obstacle with a 50% pass rate. With full scale, fleet wide, implementation of this system it is expected …

Architectural Engineering Earthquake Shake Table, Garrett Gudgel, John Whitmer, Brandan Williams

Mechanical Engineering

The Architectural Engineering Department at California Polytechnic State University, San Luis Obispo, owns and operates a single-axis earthquake shake table that previously was only capable of basic wave motion. After implementing a computer based interface to the existing system, Mechanical Engineering student seniors were able to create control algorithms that can take existing or user created acceleration data from earthquakes as well as any user defined position data to be accurately run on the earthquake shake table.

Rebounder Fatigue Test Machine, Caroline Reeves, Will Robertson, Ethan Flory

Mechanical Engineering

JumpSport, a company that designs and sells trampolines and trampoline accessories, has sponsored this senior project team to design, build, and test a trampoline fatigue test machine. The machine must simulate a person jumping on the trampoline to test the life of JumpSport’s fitness trampolines and kids’ trampolines. Partway through the design process, the objectives were altered and this senior project team was tasked with merging with another Cal Poly senior project group to create an all-inclusive test machine to accommodate both full-trampoline testing and individual bungee cord testing.

The final design is centered on a slider crank linkage driven …