Mechanical Engineering Commons^™

El, A Navigational Assistant Based Upon Echolocation, Arthur Mazer

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis investigates the integration of a parametric speaker with a microphone array to enhance the echolocation of objects. A parametric speaker focuses ultrasonic and audible waves in a specified direction. This endows the parametric speaker with the capacity to focus waves across a wide frequency spectrum enabling adaptation of the frequency to environmental considerations.Beam forming allows one to focus a microphone array in a specified direction. The thesis investigates different microphone array configurations for the purpose of enhancing the echolocation ability of an echolocation device. The primary goal of the thesis is the construction and testing of an echolocation …

Reconfigurable Python Autopilot Software For Rc Aircraft, Kate Doiron

Honors Theses

No abstract provided.

Development Of A 3-Dof Contactless Magnetic Joint Actuator, Elle Whitney

Theses and Dissertations

The magnetic joint actuator is a relatively recent research technology that expands on the brushless DC motor to encompass rotation in three degrees-of-freedom. These actuators involve a stator with a series of electromagnetic coils oriented normal to a spherical permanent magnet rotor which can be controlled by modulating the current of the stator coils. The development of a magnetic joint actuator that operates without a physical connection between the stator and the rotor has wide applications for robotics in dust-sensitive environments, where a device with bearings would otherwise falter. This work details the design, sensing, and control of such a …

A Labview-Based Open-Source Data Acquisition Program For Acoustic Emission Sensing, Harrison Greene

Mechanical Engineering Undergraduate Honors Theses

Acoustic emission sensing is a growing field of analysis and testing that benefits from its non-destructive nature, enabling operators to detect faults, the severity of impacts, the propagation of cracks, and much more without damaging the system being tested. However, the use of proprietary software to collect, analyze, and display data hinders the field, as access to this crucial information makes consistent and in-depth data analysis impossible. To this end, this paper details an open-source code made in the programming language LabVIEW for the express purpose of allowing the user to have full access to all data and fully customize …

Developing Reduced Order Models For Gas Bubble Formation In Irradiated Metals Using Integrated Phase Field Modeling And Koopman Operator Theory, John M. Eggemeyer V

All Theses

Irradiation damage in materials is prevalent in nuclear components, posing significant risks in the safety and reliability of nuclear reactors. Phase field models offer a versatile framework for modeling irradiation damage in materials at mesoscales. Such high fidelity method has been used to model the formation of fission gas bubbles superlattice, a microstructure array occurs at certain irradiation conditions (dose, dose-rate, and temperature). To overcome the high computational cost of phase field modeling, Koopman operator theory is applied to create reduced order models, allowing for instantaneous simulations of fission gas bubble behaviors. These low fidelity models are integrated into machine …

Bayesian Model Updating Of Structural Parameters Using Temperature Variation Data., Ujjwal Adhikari

Electronic Theses and Dissertations

Physical digital twins have now emerged as a technology in structural health monitoring and other domains of structural modeling. A Finite Element Model can be a tool for digital twin technology in conjunction with measured physical data. Developing an accurate digital model requires the integration of various parameters to replicate the real structure; however, temperature is dynamically changing, resulting in difficulty in the identification of structural parameters. Typically, temperature is considered noise or filtered out. Limited research has addressed the physics-based model using temperature variation related to structural modal properties. Finite Element Model Updating (FEMU) is a typical inverse problem-solving …

A Survey Of Acoustic Phenomena And Predictive Modeling Techniques For High Explosive Experimentation, Nathanael I. Breed

Senior Honors Theses

High explosive experimentation (HEE) is a technical industry that is regulated, expensive, and dangerous. Developing novel technologies to aid in predictive abilities to minimize the industry’s reliance on the need for full-scale experiments is a worthwhile endeavor. Having the capacity to make accurate predictions regarding the overpressure of a detonation wave after it has interacted with various geometries is useful, but the current state of predictive techniques is limited with many techniques, either neglecting relevant acoustic phenomena or not being able to account for complex geometries. This thesis provides an overview of several acoustic phenomena and the current state of …

Acoustic Filter For Biopharmacy, Nicholas Rivet

Three Minute Thesis (3MT)

The design and development of a novel flow induced acoustically tuned “filterless” filter is proposed. The proposed research is on developing two or more prototypes that function as a cell retention device for perfusion cell cultures used in continuous manufacturing of monoclonal antibodies and recombinant proteins. This research will provide a non-invasive, cost-effective, flexible, and robust cell retention device for sustainable manufacturing of biologics.

Investigating The Discrepancies Between Acoustic And Radar Measurements Of Water Level Using Data Analysis And Computational Modeling, Ohiedul Haque Mohammad Asad

Civil & Environmental Engineering Theses & Dissertations

Observations indicate that there is a discrepancy between water level measurements from NOAA’s acoustic gauges and radar gauges. NOAA’s acoustic gauges use a downward-looking acoustic sensor that measures the instantaneous distance from the sensor to the water level. To create a calm water surface for measurements, the sensor is placed in a PVC tube that penetrates the water surface to a certain depth. This tube is called the stilling well. In this thesis, discrepancies in water level measurements from acoustic and radar sensors were explored through data analysis and computational modeling. Specifically, the correlations between the error, which is defined …

Design And Control Of Delta Robot (Mini Review), Donia Waheed Seleem, Mohamed A. Shamseldin, Hasan Eleashy

Future Engineering Journal

The control of Delta robots, known by their parallel kinematic structure and high-speed operation, presents unique challenges and opportunities. A recent developments in Delta robot will be described. The strategies are aimed at enhancing precision, speed, and flexibility in a variety of robotic applications. Here are some key elements: trajectory tracking, motion planning, and obstacle avoidance. This review paper presents a comprehensive evaluation of three different approaches to enhancing the performance of Delta robots: structural optimization, kinematics and dynamics refinement, and control techniques that have been used. This provides a unique, multidimensional perspective that bridges the gap between isolated optimizations …

Numerical Simulation Of Airflow Properties Of The Naca 6420 Airfoil Using The Transition Rans K-Ε Model, Oluwaseyi O. Alabi, Saidat A. Salisu, Oyeyemi T. Aforolagba -Balogun, Temitope A. Ladigbolu, Ayotunde O. Fasina, Anas Bala

Al-Bahir

This study investigates the airflow properties around the airfoil using numerical simulation, addressing the longstanding challenge of accurately predicting transition phenomena in turbulent flows. The importance of this research lies in its potential to improve the design and performance of airfoils in various engineering applications, such as wind turbines, and aircraft. A custom 2-dimensional airfoil model was created using Airfoil instruments, featuring a 6% maximum curvature, 40% curvature position, and 20% thickness. COMSOL Multiphysics software performed computations at a velocity of over 19 hours, with data analyzed at 60-minute intervals. The Transition turbulent model was employed to simulate the airflow …

Introduction To The Special Issue On Verification And Validation Of Source And Propagation Models For Underwater Sounda), Kathleen J. Vigness-Raposa, Klaus Lucke, Michael A. Ainslie, Michele B. Halvorsen, Christ A. F. De Jong, Stanley J. Labak, Martin Siderius

Electrical and Computer Engineering Faculty Publications and Presentations

This joint Special Issue of JASA and JASA Express Letters focuses on underwater sound source and propagation modelling, both of ambient sound as well as sources of relevance to possible effects of sound on aquatic life, and corresponding acoustical metrics. Combining information on the sound field with information on a dose-effect relationship enables estimation of the potential effects. The Special Issue presents a collection of eighteen articles on the following topics: (1) verification of source and propagation models, (2) validation of source and propagation models, and (3) bioacoustical metrics for assessment of the risk of environmental effects. This special issue …

Development Of A Drive-Rod Unified Variable Pitch Control Mechanism For Small-Scale Horizontal Wind Turbines, Ayman I. Bakry, Mohamed Elfouly, Omar Mehrez

Journal of Engineering Research

Typically, small-scale wind turbines use either a breaking equipment or stall control methods once the wind speed exceeds its rated value. This is to limit the power extracted from the wind turbines which largely depends on the blades' shape and pitch angle. Most of small-scale wind turbines are of fixed pitch angle to avoid complexity and cost. In this work, a novel drive-rod unified variable pitch drive mechanism is proposed for blades pitch control for small-scale horizontal wind turbines. The mechanism is powered by a DC motor coupled with a lead screw which in turn is connected to the pitch …

Pd Controller Design For Automotive Magnetorheological Semi-Active Suspension System, Ayman I. Bakry, Emad M. S. El-Said, Ahmed Shehata Gad, Ahmed Abd Almoez, Omar Mehrez

Journal of Engineering Research

Recently, there is a tendency towards the utilization of magnetorheological (MR) dampers in electrical vehicles (EV) due to its adaptability of active control devices with lower requirement of large power sources compared to the active damping systems. This paper investigates the performance of the most used control technique for MR dampers used in EV, the PID controller, under different road conditions. In this investigation, the Dynamic-Damper-Motor System (ADM-EV) is used as the EV suspension system model. Meanwhile, modified Bouc-Wen model is used as the MR damper model. The design procedure for the optimum design of the system controller parameters is …

Design, Modeling, And Control Of Medical Service Quadrotor, Mohamed Eid, Anas Mohamed, Ali M. Mohamed

Journal of Engineering Research

Due to road accidents, it is difficult to supply injured people with first aid, especially in difficult-access regions. Also, uneven roads or far places pose a problem for ambulances and doctors to reach and save injured people’s lives. The paper aims to design, model, and control a drone able to fly at different heights and support patients with essential needs after accidents. The drone also contains sensors to measure blood sugar and pressure in cases of diabetic coma that require urgent intervention. The drone design was tested using SolidWorks and FLUENT to ensure safe design in different flying conditions. The …

Multiobjective Optimal Design Of Hierarchical Control Architectures For Quadcopter Systems: Linear And Hybrid Approaches, Xinhuang Wu

Theses, Dissertations and Capstones

This thesis investigates the design of many-objective optimal controllers for quadcopter unmanned aerial vehicles (UAVs), focusing on both linear and hybrid control structures. In Chapter 2, a multi-input–multi-output (MIMO) optimal control system is developed for a six-degree-of-freedom UAV actuated by four brushless DC motors. The UAV dynamics are first derived and linearized around an operating point, and then organized into a three-loop nested control structure. The outer loop computes the roll and pitch angles required to maneuver the vehicle in the global X and Y directions, the middle loop regulates attitude and altitude, and the inner loop controls the angular …

Nonlinear Bump Stiffness Model And Its Effect On Structural Stiffness And Nonlinear Rotordynamic Characteristic Of Foil Bearing, Woongeon Lee

Mechanical and Aerospace Engineering Dissertations - Archive

Bump foils are the most widely used in foil bearings, but the behaviors of bump foils are complicated, and their characteristics have been a focus of research for decades. Bump foils are usually modeled as stiffness and damping are accounted for through interactions with shaft eccentricity, loading, shaft speed and excitation frequency. These nonlinear characteristics of the bump foil of radial foil bearings can be observed during both manufacturing and operational processes because of their inherent structural properties such as bump geometry, forming process, age-hardening process and complicated contact behavior with bearing housing. These nonlinear characteristics are one of the …

Multi-Objective Design Optimization Of Hypoid Geared Rotor Systems, Xinqi Wei

Mechanical and Aerospace Engineering Dissertations - Archive

Hypoid gears represent one of the most generalized and complex forms of gearing, widely used for power transmission of skew shafts in vehicles, aviation, and marine transmission applications. Optimizing their performance remains challenging due to the complex tooth surface and contact behavior. Specifically, the design parameters of the tooth surface are multi-scale, interdependent, and subject to strong constraints, leading to strong nonlinearity and an ill-conditioned Jacobian matrix in the parameter identification model. Moreover, feasible and insensitive contact conditions are difficult to constrain due to the inherent complexity of local conjugate contact between the meshing surfaces. These challenges significantly increase optimization …

Toward Precise Long-Range Underwater Acoustic Geo-Positioning: Utilizing Vehicle Data And Deepening The Gnss Analogy Through Uncertainty Modeling, Isaac B. Salazar

Open Access Master's Theses

Electromagnetic signals, such as those used by Global Navigation Satellite Systems (GNSS), attenuate dramatically underwater, but acoustic signals can travel hundreds of kilometers, and can be used for positioning in much the same way. Concepts from GNSS can be applied to the subsurface context, as at a basic level, the principles of geo-positioning are identical. Key challenges in translating satellite positioning models to the underwater acoustic domain include differences in signal type as well as instrumentation and propagation environment. Acoustic signals travel at much slower speeds and are subject to significant environmental variability due to complex ocean dynamics. Here, the …

Impacts Of A Multi-Layered Acousto-Elastic Bottom On Sound Propagation In A Seamount Environment, Haley H. Green

Open Access Master's Theses

The New England Seamounts Acoustics (NEMSA) experiment is a comprehensive oceanographic field study aimed at investigating underwater acoustic propagation and scattering effects within a complex marine environment. The primary objective of this research is to assess the influence of seafloor and sub-bottom geoacoustic properties on acoustic propagation, signal reflections, and transmission loss at Atlantis II Seamount. Two acoustic models, BOUNCE and BELLHOP, were employed to incorporate elastic wave effects within the sub-bottom layers and facilitate the analysis of range-dependent bathymetric features. Two model scenarios were analyzed and compared, one with a layered elastic bottom and another with a fluid bottom …

Modeling The Noise Attenuation Effects Of Bubble Curtains At Coastal Virginia Offshore Wind Installation, Gavin Dies

Open Access Master's Theses

The Coastal Virginia Offshore Wind (CVOW) pilot project consists of two turbines roughly 40 km off the coast of Virginia Beach, Virginia. Water- and seabed-borne acoustic and seismic signals from impact pile driving at CVOW were recorded during the installation of these turbines in May 2020. In-water pressure signals were measured using various methods at multiple ranges. The water depth at the wind turbines and the measurement devices was approximately 26 m. During installation, one of the monopiles utilized a double bubble curtain, while the other monopile did not. This arrangement has allowed for an analysis of the bubble curtain’s …

Determination And Limitations Of Blocked Forces In Industrial Settings, Matthew Smither

Theses and Dissertations--Mechanical and Aerospace Engineering

Transfer path analysis methods have been used for decades to determine noise and vibration paths emanating from machinery. In its advent, the machinery source had to be disconnected from the receiver it was attached to in order to gain useful information about each. Further advances in methodology allowed for determining machinery input forces without decoupling them from the structures they were attached to. However, these methods were limited in that the machinery and structures were required to be treated as a system. Thus, any force data obtain was only useful in the configuration it was measured in. Finally, a method …

Acoustic Characterization Of A Quadcopter Using A Test Stand, Jared Schmal

Theses and Dissertations--Mechanical and Aerospace Engineering

Unmanned Aerial Vehicles (UAVs) with multirotor propulsion and control, commonly called drones or multicopters, generate a complex acoustic field that is not entirely understood. Many components and their interactions contribute to the overall noise level and behavior of the acoustic field. However, performing acoustic measurements on a multicopter in a confined space, such as a small anechoic chamber, can be an extremely difficult and time-consuming process. A test stand was developed to allow for rapid and safe acoustic measurements in a controlled environment. The design, development, and initial measurements are discussed. The performance and acoustic response are assessed to examine …

Analysis Of Closed-Loop Dynamical Systems Using Relu Nns, Pouya Samanipour

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis develops a framework for analyzing the stability and invariance properties of closed-loop dynamical systems whose dynamics are derived from neural networks with rectified linear units (ReLUs). The ReLU neural network defines continuous piecewise affine (PWA) functions, which makes them ideal for analysis using polyhedral geometry and optimization techniques. To begin, we introduce two exact algorithms for enumerating polytopic regions of affine behavior induced by ReLU networks: a half-space-based method that checks the feasibility of activation patterns and a geometric vertex-based method. Using these methods, we are able to perform precise region-wise analysis, and these methods serve as the …

Simulation-To-Hardware Validation Of Mpc For Binary Thruster 2d Cubesat Control, Aevar Amundinusarson Oefjoerd

Theses and Dissertations--Mechanical and Aerospace Engineering

Small satellites must execute precise, fuel-limited maneuvers under strict actuation and operational constraints. Model Predictive Control (MPC) is a suitable approach because it optimizes future actions while explicitly enforcing these limits. This work evaluates (1) whether MPC can operate in real time using binary (on/off), asymmetric thrusters, and (2) whether a high-fidelity digital twin can be used to tune and validate the controller prior to hardware testing.

An MPC framework was implemented on a planar satellite prototype that floats on air bearings, operates at 16.7 Hz (60 ms period), and uses eight binary thrusters exhibiting up to 13.2% variation in …

Knowledge Integrated Deep Learning For Enhanced Fault Diagnosis And Prognosis For Rotating Machinery And Its Applications On Marine Systems, Yunsheng Su

Dissertations, Master's Theses and Master's Reports

This dissertation develops a knowledge-informed deep learning framework for robust fault diagnosis and prognosis across various engineered systems, including bearings, lithium-ion batteries, and mooring systems in wave energy converters (WECs). A deep transfer learning (DTL) method is first developed to improve bearing fault diagnosis by fusing data from multiple sources and extracting key features using convolutional neural networks (CNNs). Building upon this, a knowledge-informed deep network (KIDN) framework is proposed, integrating physics-based features with deep learning to enhance diagnostic accuracy and generalizability. A constrained Gaussian process (CGP) model is further employed to guide adaptive network design and reduce model tuning …

Reactive Model-Free Control For Underactuated Vehicles Operating In Resource-Constrained Environments, Austin Lane Sponaugle

Graduate Theses, Dissertations, and Problem Reports (ETD)

Buoyancy-driven, underactuated vehicles offer a compelling solution for long-duration autonomous operations in constrained environments. By leveraging buoyancy to generate lift, these vehicles can remain aloft for extended periods with minimal power requirements, making them well-suited for applications in atmospheric monitoring, planetary exploration, and communications. However, their limited actuation authority, strong coupling with environmental forces, and operating domains introduce significant control challenges, including nonlinearity, sensitivity to external disturbances, and limited observability.

This work investigates the design and implementation of lightweight, reactive model-free control strategies that enable robust autonomy in such constrained settings. A digital Extremum Seeking Controller (ESC) is first implemented …

Head Mounted Surgical Robot, Mason Currens

Williams Honors College, Honors Research Projects

The purpose of this design project is to utilize a six degree of freedom, robotic system that will be head mounted device that can either assist in, or perform, facial and optical surgery. The six degree of freedom idea came from current systems used in flight simulations. By optimizing the system to fit the figure of a patient’ s head, many of the present errors in surgical robotics can be reduced. One of the major errors when using a facial tracking robot is sudden impulses, such as a cough or a twitch, that the robot can't precisely track. Mounting the …

Dynamic Force Feedback Controller Improves Metrics Of Stepping In A Biomimetic Robot Leg, Isabella Mae Kudyba

Graduate Theses, Dissertations, and Problem Reports (ETD)

Force feedback is a type of robotic control where forces are measured, fed back into the control system, and actuation is adjusted to compensate for environmental forces, with the goal of quick and precise limb positioning in walking. Robots of today use single force sensors (e.g. pressure sensitive pads, load cells) per leg which are often bulky, expensive, and susceptible to crosstalk. Walking robots often employ model predictive controllers or policy controllers trained through reinforcement learning (RL) to actuate their limbs, but these methods are time and energy consuming. Biomimetic robots offer an alternative approach, investigating biological theories with the …

Reliability Of An Extended Version Of The 3m™ Eargage Tool To Assess Earcanal Size And Assist Earplug Selection, Bastien Poissenot-Arrigoni, Laurence Martin, Alessia Negrini, Djamal Berbiche, Olivier Doutres, Franck Sgard

Études primaires

Objective: Evaluate the ability of an extended version of the 3 MTM Eargage to estimate the earcanal size and assess the likelihood that a particular earplug can fit an individual’s earcanal, ultimately serving as a tool for selecting earplugs in the field. Design: Earcanal morphology, assessed through earcanal earmolds scans, is compared to earcanal size assessed with the extended eargage (EE) via box plots and Pearson linear correlations coefficients. Relations between attenuation measured on participants (for 6 different earplugs) and their earcanal size assessed with the EE are established via comparison tests. Study sample: 121 participants exposed to occupational noise …