# Acoustics, Dynamics, and Controls Commons™

## All Articles in Acoustics, Dynamics, and Controls

1,875 full-text articles. Page 3 of 33.

Attitude Control On So(3) With Piecewise Sinusoids, 2018 University of Kentucky

#### Attitude Control On So(3) With Piecewise Sinusoids, Shaoqian Wang

##### Theses and Dissertations--Mechanical Engineering

This dissertation addresses rigid body attitude control with piecewise sinusoidal signals. We consider rigid-body attitude kinematics on SO(3) with a class of sinusoidal inputs. We present a new closed-form solution of the rotation matrix kinematics. The solution is analyzed and used to prove controllability. We then present kinematic-level orientation-feedback controllers for setpoint tracking and command following.

Next, we extend the sinusoidal kinematic-level control to the dynamic level. As a representative dynamic system, we consider a CubeSat with vibrating momentum actuators that are driven by small $\epsilon$-amplitude piecewise sinusoidal internal torques. The CubeSat kinetics are derived using Newton-Euler's ...

2018 Iowa State University

#### Transfer Matrix Modelling Of Double Helmholtz Resonator Arrays As Sound Insulating Double Panel Partitions, Sanvisna Kogelen

With rising concern pertaining to sound pollution and how it affects public health, new technologies are being considered to ensure sound is effectively attenuated and human exposure to unwanted noise is minimized. One of these technologies that separate the source from the observer is called the partition. As single wall partitions have to be physically dense to provide robust sound attenuation, they are not an efficient solution. An alternative solution is called double wall partitions. Double wall assemblies are lightweight, low-cost alternatives to single wall partitions that provide powerful transmission loss. Despite this, the performance of these assemblies suffer at ...

Terahertz Imaging Of Thin Film Layers With Matched Field Processing, 2018 Portland State University

#### Terahertz Imaging Of Thin Film Layers With Matched Field Processing, Scott Schecklman, Lisa M. Zurk

##### Electrical and Computer Engineering Faculty Publications and Presentations

Terahertz (THz) time of flight (TOF) tomography systems offer a new measurement modality for non-destructive evaluation (NDE) of the subsurface layers of protective coatings and/or laminated composite materials for industrial, security and biomedical applications. However, for thin film samples, the time-of-flight within a layer is less than the duration of the THz pulse and consequently there is insufficient range resolution for NDE of the sample under test. In this paper, matched field processing (MFP) techniques are applied to thickness estimation in THz TOF tomography applications, and these methods are demonstrated by using measured THz spectra to estimate the the ...

2018 Iowa State University

#### Analysis Of High Temperature Effects On Piezoelectric Based Ultrasonic Transducers, Prathamesh Bilgunde

Under sodium viewing (USV) using ultrasonic pulse-echo techniques offers the potential for the inspection of generation IV, liquid sodium-cooled fast reactors (SFRs) at the hot stand-by temperature (260C). However, the harsh environment effects on the transducer reduce the ultrasonic signal strength which also limits the probability of detection (POD) of the defects.

Current work presents a unified modeling and measurement-based methodology to analyze the high temperature effects on the transducer components. Resonance analysis-based characterization has shown that the conventional d33 piezoelectric parameter is not a sufficient condition to estimate resonance characteristics of high temperature ultrasonic transducers. A full piezoelectric material ...

A Transfer Operator Methodology For Optimal Sensor Placement Accounting For Uncertainty, 2018 Iowa State University

#### A Transfer Operator Methodology For Optimal Sensor Placement Accounting For Uncertainty, Himanshu Sharma, Umesh Vaidya, Baskar Ganapathysubramanian

##### Mechanical Engineering Publications

Sensors in buildings are used for a wide variety of applications such as monitoring air quality, contaminants, indoor temperature, and relative humidity. These are used for accessing and ensuring indoor air quality, and also for ensuring safety in the event of chemical and biological attacks. It follows that optimal placement of sensors become important to accurately monitor contaminant levels in the indoor environment. However, contaminant transport inside the indoor environment is governed by the indoor flow conditions which are affected by various uncertainties associated with the building systems including occupancy and boundary fluxes. Therefore, it is important to account for ...

Transfer Operator Theoretic Framework For Monitoring Building Indoor Environment In Uncertain Operating Conditions, 2018 Iowa State University

#### Transfer Operator Theoretic Framework For Monitoring Building Indoor Environment In Uncertain Operating Conditions, Himanshu Sharma, Anthony D. Fontanini, Umesh Vaidya, Baskar Ganapathysubramanian

##### Mechanical Engineering Publications

Dynamical system-based linear transfer Perron- Frobenius (P-F) operator framework is developed to address analysis and design problems in the building system. In particular, the problems of fast contaminant propagation and optimal placement of sensors in uncertain operating conditions of indoor building environment are addressed. The linear nature of transfer P-F operator is exploited to develop a computationally efficient numerical scheme based on the finite dimensional approximation of P-F operator for fast propagation of contaminants. The proposed scheme is an order of magnitude faster than existing methods that rely on simulation of an advection-diffusion partial differential equation for contaminant transport. Furthermore ...

Habitat Use Of Blacktip Sharks (Carcharhinus Limbatus) At Fishing Piers, 2017 Coastal Carolina University

#### Habitat Use Of Blacktip Sharks (Carcharhinus Limbatus) At Fishing Piers, Kelsey L. Spencer

##### Electronic Theses and Dissertations

Blacktip sharks (Carcharhinus limbatus) can be observed near fishing piers throughout the summer along the northeast coast of South Carolina. These piers attract and support a wide variety of potential prey and sharks are able to forage on fishers’ discards with minimal energetic cost. I tagged 12 blacktip sharks with acoustic transmitters, monitored piers with acoustic receivers, and conducted pier-creel surveys to determine the habitat use of blacktip sharks at fishing piers, factors that influenced residence time and presence/absence at piers, and any cyclical patterns in visits to piers. Data were analyzed with pier association indices (PAI), mixed models ...

Low-Cost Control Engineering Experiments, 2017 Western Michigan University

#### Low-Cost Control Engineering Experiments, Megan Arduin

##### Honors Theses

The disciplines found within the area of motion and controls is a vital element of each engineer’s education. The ability to understand and then control dynamic systems is a fundamental skill required for many working engineers today. The aim of this project is to further develop the tools and methods available to teach and prepare engineering students to effectively design control system architecture, and then successfully implement their design into real world systems. The main goal is to design an apparatus that can be used to teach control system methods and has an affordable price. There are few experiments ...

Museum Wave Tank Design, 2017 Cal Poly Slo

#### Museum Wave Tank Design, David James Streng, Lisa Michelle Dischinger, John Frederick Niemoller

##### Mechanical Engineering

The Santa Maria Discovery Museum would like to add a tsunami wave tank to be one of their demonstrations. The wave tank needs to draw the attention of their young crowd and be educationally informative about the shapes and effects of waves. As this is a museum demonstration for children, the structure, user interface, and wave making mechanism must be durable.

We are a senior project team from California Polytechnic State University that worked on this project with Allan Hancock College and Stanford University. We created waves by rapidly moving a plunger vertically in the water column. This project allows ...

Dyno-Mite Redesign, 2017 California Polytechnic State University, San Luis Obispo

#### Dyno-Mite Redesign, Brandon Joseph Miller, Daniel Robert Hoffman, Richard Demedici Young

##### Mechanical Engineering

The Cal Poly Mechanical Control Systems Laboratory currently employs an outdated device, known as the Motomatic, to teach students about various motor characteristics and control methods. These include open-loop vs. closed-loop control, speed vs. position control, and DC motor response curves. The current device does not function properly and produces unreliable data due to overwhelming non-linear effects such as stiction and shaft misalignment. Our team was tasked with designing a replacement device that retains many of the same educational goals as the original lab procedure, while also adding new educational goals pertaining to the device system dynamics. The new apparatus ...

2017 California Polytechnic State University, San Luis Obispo

#### Development Of A Rotordynamic Signal Processing Matlab Interface And A Two-Disk Rotor Model, David L. Baker

##### Master's Theses and Project Reports

Using MATLAB and a National Instruments data acquisition card, a signal processing program meant to monitor the behavior of rotordynamic systems in real-time was developed and tested. By using traditional analysis methods in this field of engineering, commonly desired data representations such as bode, polar, orbit, full spectrum plots were able to be produced to a very high accuracy. Additional capabilities offered by this application are slow roll compensation, synchronous and sub-synchronous filtering, and true three dimensional plotting. The verification of this program was done by comparing the results to the ones acquired with Bently Nevada’s “Automated Diagnostics for ...

Hybrid Attitude Control And Estimation On So(3), 2017 The University of Western Ontario

#### Hybrid Attitude Control And Estimation On So(3), Soulaimane Berkane

##### Electronic Thesis and Dissertation Repository

This thesis presents a general framework for hybrid attitude control and estimation design on the Special Orthogonal group SO(3). First, the attitude stabilization problem on SO(3) is considered. It is shown that, using a min-switch hybrid control strategy designed from a family of potential functions on SO(3), global exponential stabilization on SO(3) can be achieved when this family of potential functions satisfies certain properties. Then, a systematic methodology to construct these potential functions is developed. The proposed hybrid control technique is applied to the attitude tracking problem for rigid body systems. A smoothing mechanism is proposed ...

2017 Louisiana State University and Agricultural and Mechanical College

#### Nonlinear Model-Based Control For Neuromuscular Electrical Stimulation, Ruzhou Yang

##### LSU Doctoral Dissertations

Neuromuscular electrical stimulation (NMES) is a technology where skeletal muscles are externally stimulated by electrodes to help restore functionality to human limbs with motor neuron disorder. This dissertation is concerned with the model-based feedback control of the NMES quadriceps muscle group-knee joint dynamics. A class of nonlinear controllers is presented based on various levels of model structures and uncertainties. The two main control techniques used throughout this work are backstepping control and Lyapunov stability theory.

In the first control strategy, we design a model-based nonlinear control law for the system with the exactly known passive mechanical that ensures asymptotical tracking ...

Measurement Of Speed Of Sound Profile Using Laaces Balloon, 2017 McNeese State University

#### Measurement Of Speed Of Sound Profile Using Laaces Balloon, Zhuang Li, Brett Schaefer, Brian Schaefer, William Dever, Tyler Morgan, Matthew Foltz

##### 2017 Academic High Altitude Conference

The goal of this mission is to test the speed of sound at different altitudes and ultimately at a maximum height of 100,000 feet (30 km). In conjunction with this testing, environmental parameters including temperature, pressure, and humidity are measured and used to calculate the speed of sound to compare to the measured results. The team constructed the payload “Dorothy” using polystyrene foam due to its lightweight and thermal isolation property. An ultrasonic sensor with a reflection mirror were installed outside payload box to measure speed of sound. All the sensors were calibrated. Software for the project was developed ...

2017 University of Nebraska - Lincoln

#### Cam-Based Pose-Independent Counterweighting For Partial Body-Weight Support In Rehabilitation, Ashish Shinde

##### Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

This thesis presents the design and testing of a body weight support system for gait training in a two-dimensional workspace. Extension of the system to a three-dimensional workspace is not within the scope of this thesis.

Gait dysfunctions are changes in normal walking patterns, often related to a disease or abnormality in different areas of the body. There are numerous body weight support (BWS) systems present in the market which are applied to rehabilitation scenarios in mobility recovery like in gait training. But most of these BWE systems are costly and generally are stationary devices. A major drawback of such ...

2017 Florida International University

#### Detecting Structural Defects Using Novel Smart Sensory And Sensor-Less Approaches, Amin Baghalian

##### FIU Electronic Theses and Dissertations

Monitoring the mechanical integrity of critical structures is extremely important, as mechanical defects can potentially have adverse impacts on their safe operability throughout their service life. Structural defects can be detected by using active structural health monitoring (SHM) approaches, in which a given structure is excited with harmonic mechanical waves generated by actuators. The response of the structure is then collected using sensor(s) and is analyzed for possible defects, with various active SHM approaches available for analyzing the response of a structure to single- or multi-frequency harmonic excitations. In order to identify the appropriate excitation frequency, however, the majority ...

2017 Iowa State University

#### Comparison Of Acoustoelastic Lamb Wave Propagation In Stressed Plates For Different Measurement Orientations, Ning Pei, Leonard J. Bond

##### Aerospace Engineering Publications

High order Lamb waves are investigated for the effects of stress on both symmetrical and anti-symmetrical modes in an aluminum plate for wave propagation and load parallel. Data are compared with those for the case of load and measurement axis perpendicular. It is the S1 mode which exhibits significantly higher sensitivity to stress than other Lamb modes. For aluminum the use of the S1 mode for stress measurement is found to be about six times more sensitive, than bulk waves, for the load-measurement axes parallel case and this compares with about ten times for the case of load-measurement axes perpendicular.

Dynamic Characterization Of Periodic Lattice Of Elastically-Connected Bi-Stable Elements Under Seismic Excitation, 2017 Purdue University

#### Dynamic Characterization Of Periodic Lattice Of Elastically-Connected Bi-Stable Elements Under Seismic Excitation, Lingwei Meng, Myungwon Hwang, Andres F. Arrieta Ph.D.

##### The Summer Undergraduate Research Fellowship (SURF) Symposium

Metamaterials are engineered materials, typically in periodic arrangements, which exhibit unconventional or extreme properties not found in nature. Understanding the dynamics of metamaterials enables the design of structures with specific functionalities. The dynamics of metamaterials in linear regime has been relatively well studied in recent years, however the unique phenomena arising from nonlinearities in metamaterials are yet to be explored. In this paper, we focus on an array of bi-stable elements connected by elastic springs under various forms of external excitations acting on the entire system. The general equations of motion are derived to handle any degree-of-freedom (DoF) systems of ...

Generation Of Inhomogeneous Acoustic Waves Using An Array Of Loudspeakers, 2017 Purdue University

#### Generation Of Inhomogeneous Acoustic Waves Using An Array Of Loudspeakers, Samuel E. Wonfor, Trevor A. Kyle, J. Stuart Bolton, Jeffrey F. Rhoads

##### The Summer Undergraduate Research Fellowship (SURF) Symposium

In previous studies it has been shown that pressure fields created by inhomogeneous sound waves (waves which decay in a direction perpendicular to their propagation direction) are able to transmit energy into objects more effectively than ones created by conventional sound waves. This behavior may be useful in the detection of hidden explosive threats. To explore this, a device capable of constructing inhomogeneous waves is being developed. The proposed device is an acoustic array consisting of several high-frequency speakers. The speakers are independently driven to construct a desired inhomogeneous pressure field on a target surface. Inhomogeneous pressure fields were reconstructed ...

The Influence Of Macroscale Stress Concentrations On The Near-Resonant Thermomechanics Of Mock Energetic Materials, 2017 Western Kentucky University

#### The Influence Of Macroscale Stress Concentrations On The Near-Resonant Thermomechanics Of Mock Energetic Materials, Lauren A. Cooper, Allison R. Range, Jeffrey F. Rhoads

##### The Summer Undergraduate Research Fellowship (SURF) Symposium

The characterization of particulate composite energetic materials, both with and without stress concentration, is currently of great interest to the defense community. This work seeks to further characterize the self-heating effect of composite energetic plates, particularly around regions of high stress, when subjected to harmonic excitation near resonance. Mock energetic plates with macroscale stress concentrations are prepared in various compositions based on the PBXN-109 formulation, and are tested near the first resonant frequency using an electrodynamic shaker. The resulting mechanical and thermal responses are recorded using a laser Doppler vibrometer and an infrared camera, respectively. Upon comparison between the regions ...