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Articles 1 - 30 of 1990

Full-Text Articles in Mechanical Engineering

Mathematical Modeling Of A Two Wheeled Robotic Base, Kathryn Remell May 2021

Mathematical Modeling Of A Two Wheeled Robotic Base, Kathryn Remell

Mechanical Engineering Undergraduate Honors Theses

This thesis presents the concept of using a two wheeled robot on the moon and briefly explores the requirements for successful long term operation in a lunar environment. The mathematical model for the motion of a robot with two fixed wheels on a differential drive with in a global reference frame. The robot is assumed to be balancing a platform so the mathematical model to balance the platform with wheel motors is also developed and briefly evaluated.


Development And Validation Of A Nonlinear Dynamic Model For Tuned Liquid Multiple Columns Dampers, Liang Cao, Yongqiang Gong, Filippo Ubertini, Hao Wu, An Chen, Simon Laflamme Nov 2020

Development And Validation Of A Nonlinear Dynamic Model For Tuned Liquid Multiple Columns Dampers, Liang Cao, Yongqiang Gong, Filippo Ubertini, Hao Wu, An Chen, Simon Laflamme

Civil, Construction and Environmental Engineering Publications

The tuned liquid column damper (TLCD), a passive damping device consisting of a large U-tube with oscillating liquid, has been shown to be effective at mitigating structural responses under natural hazards. Aside from their bandwidth-limited mitigation capabilities, a key limitation of TLCDs is in their large geometries that occupy large space often at prime locations. A solution is to implement multi-columned versions, termed tuned liquid multiple columns dampers (TLMCDs), which have the potential to be tuned to multiple frequencies and occupy less space by leveraging the multiple columns to allow fluid movement. However, mathematical models characterizing their dynamic behavior must ...


Data Acquisition, Analysis, And Modeling Of Rotordynamic Systems, Michael P. Mullen Jun 2020

Data Acquisition, Analysis, And Modeling Of Rotordynamic Systems, Michael P. Mullen

Master's Theses

Data acquisition systems for rotordynamic analysis and machine vibration were explored for the purpose of replacing the obsolete Bently Nevada ADRE 208 and ADRE for Windows system. These included the development of Matlab based custom data acquisition systems and a user interface. A model of an anisotropic rotor response undergoing transient speed was developed for the rapid prototyping and testing of data acquisition systems. Several methods for the measurement of amplitudes and phase in both the time domain and frequency domain were developed and compared. An alternate data acquisition method which is more inline with industry practices was created for ...


Vibration Isolation System, Bradley Y. Kwan, Bailey Groh, Max Wu, Nicole Yen Jun 2020

Vibration Isolation System, Bradley Y. Kwan, Bailey Groh, Max Wu, Nicole Yen

Mechanical Engineering

The Vibration Isolation System Senior Project is a collaborative group project between its sponsor, Maxar Technologies, and a team of students from Cal Poly - SLO to effectively design, manufacture, and test a structural assembly for satellites, isolating vibrations during launch and orbit conditions. After initial sponsor contact, requirements and needs were set which dictated deliverables for the senior project group. The group performed analyses to validate all design decisions, including a modified concept and design direction, selection of a prototype viscoelastic damping material, preliminary testing to validate design specifications, and detailed design and analysis toward a finalized design. Instead of ...


Design Of Structural Stand For High-Precision Optics Microscopy, Sara T. Novell Jun 2020

Design Of Structural Stand For High-Precision Optics Microscopy, Sara T. Novell

Master's Theses

Lawrence Livermore National Lab (LLNL) is home to the National Ignition Facility (NIF), the world’s largest and most energetic laser. Each of the 192 beamlines contains dozens of large optics, which require offline damage inspection using large, raster-scanning microscopes. The primary microscope used to measure and characterize the optical damage sites has a precision level of 1 µm. Mounted in a class 100 clean room with a raised tile floor, the microscope is supported by a steel stand that structurally connects the microscope to the concrete ground. Due to ambient vibrations experienced in the system, the microscope is only ...


Design Of Versatile Feedback Control System Components For Selective Laser Sintering, Thomas Chessman May 2020

Design Of Versatile Feedback Control System Components For Selective Laser Sintering, Thomas Chessman

University Scholar Projects

Selective laser sintering (SLS) is an additive manufacturing technique that involves using a laser to fuse powdered material together, layer by layer, in order to create a 3-D product. Despite its numerous benefits over traditional methods of manufacturing, including higher efficiency, versatility, and the ability to process many materials, selective laser sintering suffers from its propensity to generate structural errors during operation.

Feedback control has been shown to improve fabrication quality in other laser-based additive manufacturing techniques when implemented properly. Widespread exploration of applying feedback control in SLS might lead to significant performance improvements in this form of manufacturing.

This ...


Application Of Optimal Switching Using Adaptive Dynamic Programming In Power Electronics, Ataollah Gogani Khiabani May 2020

Application Of Optimal Switching Using Adaptive Dynamic Programming In Power Electronics, Ataollah Gogani Khiabani

Mechanical Engineering Research Theses and Dissertations

In this dissertation, optimal switching in switched systems using adaptive dynamic programming (ADP) is presented. Two applications in power electronics, namely single-phase inverter control and permanent magnet synchronous motor (PMSM) control are studied using ADP. In both applications, the objective of the control problem is to design an optimal switching controller, which is also relatively robust to parameter uncertainties and disturbances in the system. An inverter is used to convert the direct current (DC) voltage to an alternating current (AC) voltage. The control scheme of the single-phase inverter uses a single function approximator, called critic, to evaluate the optimal cost ...


Control And Locomotion Of Inertially And Magnetically Actuated Multi-Scale Robotic Systems, Ehab Al Khatib May 2020

Control And Locomotion Of Inertially And Magnetically Actuated Multi-Scale Robotic Systems, Ehab Al Khatib

Mechanical Engineering Research Theses and Dissertations

In this research, two actuation systems were introduced, inertial and magnetic actuation. In the inertial actuation, the robot used the transfer of momentum to navigate, and this momentum could be generated by spinning masses and wheels. Recent studies in our System Laboratory proved that a wide range of inertially actuated locomotion systems could be generated. This can be achieved by using a family tree approach, starting from a very simple system, and progressively evolving it to more complex ones. The motion diversity of these robots inspired us to extend their locomotion from a macro scale to millimeter and micro scales ...


A Perceptual Evaluation Of Short-Time Fourier Transform Window Duration And Divergence Cost Function On Audio Source Separation Using Non-Negative Matrix Factorization, Ryan J. Miller May 2020

A Perceptual Evaluation Of Short-Time Fourier Transform Window Duration And Divergence Cost Function On Audio Source Separation Using Non-Negative Matrix Factorization, Ryan J. Miller

Audio Engineering Theses

Non-negative matrix factorization (NMF) is an established method of performing audio source separation. Previous studies used NMF with supplementary systems to improve performance, but little has been done to investigate perceptual effects of NMF parameters. The present study aimed to evaluate two NMF parameters for speech enhancement: the short-time Fourier transform (STFT) window duration and divergence cost function. Two experiments were conducted: the first investigated the effect of STFT window duration on target speech intelligibility in a sentence keyword identification task. The second experiment had participants rate residual noise levels present in target speech using three different cost functions: the ...


Dynamic Characterization Of Duroprotect, A Fiber-Reinforced Ballistics Composite, Ivy A. Turner May 2020

Dynamic Characterization Of Duroprotect, A Fiber-Reinforced Ballistics Composite, Ivy A. Turner

Honors Theses

Dynamic characterization of materials has become increasingly common, as it is important to understand how materials behave under sudden loads. Understanding these properties can aid in material selection for novel designs. DuroProtect, a fiber-reinforced ballistics composite developed by Rӧchling, was tested for its dynamic properties at high strain-rates. The Split Hopkinson Pressure Bar (SHPB) test was used to obtain dynamic properties at high strain-rates under compressive loading conditions. Tests were initially conducted to validate force equilibriums for each sample. The data measured from the strain gages mounted on the incident and transmission bars and the elastic wave propagation theories yields ...


Analog Versus Digital Guitar Pedals, Shaping Guitar Tones And Sparking Debates, Cameron Karren May 2020

Analog Versus Digital Guitar Pedals, Shaping Guitar Tones And Sparking Debates, Cameron Karren

Capstone Projects and Master's Theses

This paper goes into the history of guitar effects, what exactly they are, how they have evolved, and what they are like today. It also presents the results of an experiment that compares perceptions of differences between analog and digital guitar pedals.


Development And Test Of High Temperature Surface Acoustic Wave Gas Sensors, Armando E. Ayes Moncada May 2020

Development And Test Of High Temperature Surface Acoustic Wave Gas Sensors, Armando E. Ayes Moncada

Electronic Theses and Dissertations

The demand for sensors in hostile environments, such as power plant environments, exhaust systems and high-temperature metallurgy environments, has risen over the past decades in a continuous attempt to increase process control, improve energy and process efficiency in production, reduce operational and maintenance costs, increase safety, and perform condition-based maintenance in equipment and structures operating in high-temperature, harsh-environment conditions. The increased reliability, improved performance, and development of new sensors and networks with a multitude of components, especially wireless networks, are the target for operation in harsh environments. Gas sensors, in particular hydrogen gas sensors, operating above 200°C are required ...


Olivet Nazarene University Telescope Vibration, Jake Butterfield, Kamil Michorczyk, Nathan Eckerle Apr 2020

Olivet Nazarene University Telescope Vibration, Jake Butterfield, Kamil Michorczyk, Nathan Eckerle

Scholar Week 2016 - present

Our project entails the use of vibration analysis to come up with a solution to the vibrational issues the ONU Telescope on top of Reed Hall of Science is currently experiencing. In its current state, the telescope produces images that are shaky and unclear; thus, rendering it useless for its intended research purposes. This shaky image is a result of excessive vibrations on and around the telescope. Within this project we diagnosed the source of the vibrations, brainstormed different design possibilities, chose the best one that is most feasible and meets the client’s needs, and proposed a detailed final ...


Manipulation And Patterning Of Mammalian Cells Using Vibrations And Acoustic Forces, Joel Cooper Apr 2020

Manipulation And Patterning Of Mammalian Cells Using Vibrations And Acoustic Forces, Joel Cooper

Graduate Theses and Dissertations

Recently, there has been a surge in researchers and scientists investigating different methods which move, manipulate, and pattern biological cells. Multiple different mechanisms can be used for cellular manipulation, microfluidics, biochemical queues, and even optics, just to name a few. However, all techniques have their downsides. A majority of these methods require expensive equipment or reagents and can only manipulate a small number of cells at a time.

Some of the most common cell manipulation devices utilize acoustic pressure waves to move the cells to desired locations. Currently, it is unknown what level of force from these types of devices ...


A Study Of The Aeroacoustics Of Swept Propellers For Small Unmanned Aerial Vehicles, Arthur David Wiedemann Apr 2020

A Study Of The Aeroacoustics Of Swept Propellers For Small Unmanned Aerial Vehicles, Arthur David Wiedemann

Mechanical & Aerospace Engineering Theses & Dissertations

In recent years, small unmanned aerial vehicles (UAVs) have increased in availability and use in both public and commercial sectors. This increased use of small UAVs or “drones” has the unfortunate consequence of introducing excessive noise into communities where they operate. Implementation of noise reduction methods is necessary if we wish to see expanded use of drones in public areas. With electric propulsion, the primary source of noise is the rotor/propeller used in contemporary multi-rotor configurations. In this thesis, the aerodynamics and acoustic behavior of various swept propellers is examined with computational and experimental methods.

A family of propeller ...


Investigating The Feasibility And Stability For Modeling Acoustic Wave Scattering Using A Time-Domain Boundary Integral Equation With Impedance Boundary Condition, Michelle E. Rodio Apr 2020

Investigating The Feasibility And Stability For Modeling Acoustic Wave Scattering Using A Time-Domain Boundary Integral Equation With Impedance Boundary Condition, Michelle E. Rodio

Mathematics & Statistics Theses & Dissertations

Reducing aircraft noise is a major objective in the field of computational aeroacoustics. When designing next generation quiet and environmentally friendly aircraft, it is important to be able to accurately and efficiently predict the acoustic scattering by an aircraft body from a given noise source. Acoustic liners are an effective tool for aircraft noise reduction and are characterized by a frequency-dependent impedance. Converted into the time-domain using Fourier transforms, an impedance boundary condition can be used to simulate the acoustic wave scattering by geometric bodies treated with acoustic liners

This work considers using either an impedance or an admittance (inverse ...


Adaptable Clean Energy Laboratory, Joao Marcelo Rocha Belmonte, Marc D. Compere Jan 2020

Adaptable Clean Energy Laboratory, Joao Marcelo Rocha Belmonte, Marc D. Compere

Sustainability Conference

The Adaptable Clean Energy (ACE) Lab is a real-world, long term, test platform that will guide the courses of the Energy Systems track. The lab will provide realistic electrical and HVAC loads that mimic a solar powered office. The lab is a 20’ high cube shipping container modified with a door, windows, lights computers, air conditioner and appliances. The lab is Net-Zero and powered entirely from the sun. Two insulation test sections expose the exterior walls for research access to real external heat loads in a real building


Multi-Objective Optimization Of Multi-Loop Control Systems, Yuekun Chen Jan 2020

Multi-Objective Optimization Of Multi-Loop Control Systems, Yuekun Chen

Theses, Dissertations and Capstones

Cascade Control systems are composed of inner and outer control loops. Compared to the traditional single feedback controls, the structure of cascade controls is more complex. As a result, the implementation of these control methods is costly because extra sensors are needed to measure the inner process states. On the other side, cascade control algorithms can significantly improve the controlled system performance if they are designed properly. For instance, cascade control strategies can act faster than single feedback methods to prevent undesired disturbances, which can drive the controlled system’s output away from its target value, from spreading through the ...


Dynamic Testing: An Experimental Approach To Defect Identification In Additive Manufactured Parts, Aimee Allen Jan 2020

Dynamic Testing: An Experimental Approach To Defect Identification In Additive Manufactured Parts, Aimee Allen

Dissertations, Master's Theses and Master's Reports

Today’s additive manufacturing (AM) industry produces specialized parts at low volume or with complex geometries. Traditional testing methods are effective, but costly and time consuming to perform. The AM industry lacks an optimized testing method for identifying internal defects that occur in parts. The evaluation of multiple parts printed on the same build plate for internal defects using various nondestructive (dynamic) testing techniques is presented. From these experiments, perspective was gained on when and how dynamic testing can be used to find defects. Insight gained from these experiments can help the industry in future testing for internal defects.


Numerical And Experimental Studies Of Blocked Force Determination On An Offset Interface For Plate And Shell Structures And Duct Acoustic Systems, Keyu Chen Jan 2020

Numerical And Experimental Studies Of Blocked Force Determination On An Offset Interface For Plate And Shell Structures And Duct Acoustic Systems, Keyu Chen

Theses and Dissertations--Mechanical Engineering

Blocked force determination is an alternative to the more routine method of inverse force determination using classical transfer path analysis. One advantage of determining blocked forces is that there is no need for the source to be detached or isolated from the system. Another advantage is that calculated blocked forces are appropriate when modifications are made on the receiver side of the interface. This insures that the blocked forces are suitable for utilization in analysis models where receiver system modifications are considered. Difficulties in using the approach arise when interface locations are difficult to instrument. This thesis demonstrates that blocked ...


Dual-Axis Solar Tracker, Bryan Kennedy Jan 2020

Dual-Axis Solar Tracker, Bryan Kennedy

All Undergraduate Projects

Renewable energies, and fuels that are not fossil fuel-based, are one of the prolific topics of debate in modern society. With climate change now becoming a primary focus for scientists and innovators of today, one of the areas for the largest amount of potential and growth is that of the capturing and utilization of Solar Energy. This method involves using a mechanical system to track the progression of the sun as it traverses the sky throughout the day. A dual-axis solar tracker such as the one designed and built for this project, can follow the sun both azimuthally and in ...


Sound Propagation In Viscous Flows Using Piezoelectric Sensors And Non-Destructive Propagation Techniques And Its Applications, Ahmed M. Abdulkareem Jan 2020

Sound Propagation In Viscous Flows Using Piezoelectric Sensors And Non-Destructive Propagation Techniques And Its Applications, Ahmed M. Abdulkareem

Theses and Dissertations

Structural non-destructive evaluation techniques are applied to viscous flows to detect fluid property changes. The main operating principle consists of an actuator which provides a stimulus, and a sensor to receive a signal traveling to a fluid domain. The main challenge of the operating principle consists of investigating waves traveling in a viscous flow. Traveling waves utilizing a piezoelectric actuator-sensor pair are modeled and the results are validated experimentally. ANSYS models, coupled with a two-way fluid-solid interaction model, are built to investigate how far a signal travels and what frequency ranges are of interest. The numerical model includes modeling three ...


Filtered-Dynamic-Inversion Control For Unknown Minimum-Phase Systems With Unknown Relative Degree, Sumit Suryakant Kamat Jan 2020

Filtered-Dynamic-Inversion Control For Unknown Minimum-Phase Systems With Unknown Relative Degree, Sumit Suryakant Kamat

Theses and Dissertations--Mechanical Engineering

We present filtered-dynamic-inversion (FDI) control for unknown linear time-invariant systems that are multi-input multi-output and minimum phase with unknown-but-bounded relative degree. This FDI controller requires limited model information, specifically, knowledge of an upper bound on the relative degree and knowledge of the first nonzero Markov parameter. The FDI controller is a single-parameter high-parameter-stabilizing controller that is robust to uncertainty in the relative degree. We characterize the stability of the closed-loop system. We present numerical examples, where the FDI controller is implemented in feedback with mathematical and physical systems. The numerical examples demonstrate that the FDI controller for unknown relative degree ...


Fast Decision-Making Under Time And Resource Constraints, Kyle Gabriel Lassak Jan 2020

Fast Decision-Making Under Time And Resource Constraints, Kyle Gabriel Lassak

Graduate Theses, Dissertations, and Problem Reports

Practical decision makers are inherently limited by computational and memory resources as well as the time available in which to make decisions. To cope with these limitations, humans actively seek methods which limit their resource demands by exploiting structure within the environment and exploiting a coupling between their sensing and actuation to form heuristics for fast decision-making. To date, such behavior has not been replicated in artificial agents. This research explores how heuristics may be incorporated into the decision-making process to quickly make high-quality decisions through the analysis of a prominent case study: the outfielder problem. In the outfielder problem ...


Deep Learning Of Nonlinear Dynamical System, Aditya Wagh Jan 2020

Deep Learning Of Nonlinear Dynamical System, Aditya Wagh

Dissertations, Master's Theses and Master's Reports

A data-driven approach, such as neural networks, is an alternative to traditional parametric-model methods for nonlinear system identification. Recently, long Short- Term Memory (LSTM) neural networks have been studied to model nonlinear dynamical systems. However, many of these contributions are made considering that the input to the system is known or measurable, which often may not be the case. This thesis presents a method based on LSTM for output-only modeling, identification, and prediction of nonlinear systems. A numerical study is performed and discussed on Duffing systems with various cubic nonlinearity.


Analysis Of A Circular Resonant Plate For Shock Testing, Jon Markl Jan 2020

Analysis Of A Circular Resonant Plate For Shock Testing, Jon Markl

Dissertations, Master's Theses and Master's Reports

Designing a resonant plate for shock test specifications involves an understanding of how a system will respond with a given set of input and output locations in all three directions. To investigate how to effectively change the off-axis responses to meet test specifications, a finite element model (FEM) was created and examinations of input location/angle of impact, placement of the test fixture, and placement of the impact pad were conducted. The primary tool used to determine how a structure will respond to a given input at a given output on the test structure was done using the shock response ...


Active Noise Control Using Carbon Nanotube Thermophones: Case Study For An Automotive Hvac Application, Walker H. Nelson Jan 2020

Active Noise Control Using Carbon Nanotube Thermophones: Case Study For An Automotive Hvac Application, Walker H. Nelson

Dissertations, Master's Theses and Master's Reports

The goal of this project was to reduce the overall noise levels emitted by the HVAC components in a vehicle’s cabin. More specifically, the feasibility of achieving this goal using two key technologies was investigated.

The first of these technologies, Active Noise Control (ANC), is a noise attenuation technique that relies on destructive interference that “cancels” unwanted noise. Typically used in situations where physical constraints prevent passive attenuation techniques from being used, ANC is known for its high size-to-effectiveness ratio. This benefit cannot be gained without a cost however; the complexity of ANC systems is significantly higher than their ...


Sensor-As-A-Service: Convergence Of Sensor Analytic Point Solutions (Snaps) And Pay-A-Penny-Per-Use (Pappu) Paradigm As A Catalyst For Democratization Of Healthcare In Underserved Communities, Victoria Morgan, Lisseth Casso-Hartmann, David Bahamon-Pinzon, Kelli Mccourt, Robert G. Hjort, Sahar Bahramzadeh, Irene Velez-Torres, Eric Mclamore, Carmen Gomes, Evangelyn C. Alocilja, Nirajan Bhusal, Sunaina Shrestha, Nisha Pote, Ruben Kenny Briceno, Shoumen Palit Austin Datta, Diana C. Vanegas Jan 2020

Sensor-As-A-Service: Convergence Of Sensor Analytic Point Solutions (Snaps) And Pay-A-Penny-Per-Use (Pappu) Paradigm As A Catalyst For Democratization Of Healthcare In Underserved Communities, Victoria Morgan, Lisseth Casso-Hartmann, David Bahamon-Pinzon, Kelli Mccourt, Robert G. Hjort, Sahar Bahramzadeh, Irene Velez-Torres, Eric Mclamore, Carmen Gomes, Evangelyn C. Alocilja, Nirajan Bhusal, Sunaina Shrestha, Nisha Pote, Ruben Kenny Briceno, Shoumen Palit Austin Datta, Diana C. Vanegas

Mechanical Engineering Publications

In this manuscript, we discuss relevant socioeconomic factors for developing and implementing sensor analytic point solutions (SNAPS) as point-of-care tools to serve impoverished communities. The distinct economic, environmental, cultural, and ethical paradigms that affect economically disadvantaged users add complexity to the process of technology development and deployment beyond the science and engineering issues. We begin by contextualizing the environmental burden of disease in select low-income regions around the world, including environmental hazards at work, home, and the broader community environment, where SNAPS may be helpful in the prevention and mitigation of human exposure to harmful biological vectors and chemical agents ...


Industrial Scale Large Eddy Simulations (Les) With Adaptive Octree Meshes Using Immersogeometric Analysis, Kumar Saurabh, Boshun Gao, Milinda Fernando, Songzhe Xu, Biswajit Khara, Makrand A. Khanwale, Ming-Chen Hsu, Adarsh Krishnamurthy, Hari Sundar, Baskar Ganapathysubramanian Jan 2020

Industrial Scale Large Eddy Simulations (Les) With Adaptive Octree Meshes Using Immersogeometric Analysis, Kumar Saurabh, Boshun Gao, Milinda Fernando, Songzhe Xu, Biswajit Khara, Makrand A. Khanwale, Ming-Chen Hsu, Adarsh Krishnamurthy, Hari Sundar, Baskar Ganapathysubramanian

Mechanical Engineering Publications

We present a variant of the immersed boundary method integrated with octree meshes for highly efficient and accurate Large-Eddy Simulations (LES) of flows around complex geometries. We demonstrate the scalability of the proposed method up to O(32K) processors. This is achieved by (a) rapid in-out tests; (b) adaptive quadrature for an accurate evaluation of forces; (c) tensorized evaluation during matrix assembly. We showcase this method on two non-trivial applications: accurately computing the drag coefficient of a sphere across Reynolds numbers 1−106 encompassing the drag crisis regime; simulating flow features across a semi-truck for investigating the effect of platooning ...


Wireless Wearable System For The Assessment Of Gait, Abdallah Jabr Jan 2020

Wireless Wearable System For The Assessment Of Gait, Abdallah Jabr

Mechanical Engineering Research Theses and Dissertations

This work investigates the development and use of a wireless wearable system for the assessment of gait. The system proposed consists of a sensor module that is attached to the foot. The sensor proposed is an inertial measurement unit, often abbreviated as IMU - a 9-axis System in Package (SiP) including a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer, as well as a fusion engine for signal processing. While the focus of this work is on evaluating gait metrics, the performance of the proposed IMU in evaluating orientation is quantified. In doing this work, we try to address the ...