Engineering Commons^™

Torque Response Of Thin-Film Ferromagnetic Prisms In Uniform Magnetic Fields At Macro And Micro Scales, Soroosh Torabi

Theses and Dissertations--Mechanical and Aerospace Engineering

The non-contact nature of magnetic actuation makes it useful in a variety of microscale applications, from microfluidics and lab-on-a-chip devices to classical MEMS or even microrobotics. Ferromagnetic materials like nickel are particularly attractive, because they can be easily deposited and patterned using traditional lithography-based microscale fabrication methods. However, the response of ferromagnetic materials in a magnetic field can be difficult to predict. When placed in a magnetic field, high magnetization is induced in these ferromagnetic materials, which in turn generates force and/or torque on the ferromagnetic bodies. The magnitude and direction of these forces are highly dependent on the type …

Effects Of Temperature, Orientation, Load Level And Indenter Shape On The Indentation Response Of Niti-Based Shape Memory Alloys, Peizhen Li

Theses and Dissertations--Mechanical and Aerospace Engineering

Owing the capability of recovering large deformations through reversible phase transformation, shape memory alloys (SMAs) are well-known for their unique behaviors such as shape memory effect (SME) and superelasticity (SE), which can also be characterized by instrumented indentation techniques. Nickel titanium (NiTi) SMAs have been extensively used for nano/micro-indentation studies and widely applied to biomedical and other elaborate medical devices.

In this study, indentation responses of NiTi, NiTiHf, NiTiHfPd and NiTiHfCu alloys were investigated using spherical and Berkovich indenters at room temperature. Spherical and Berkovich indentation hardness, modulus, and work/depth recoverable ratio of these NiTi-based alloys were revealed as a …

Analytical And Boundary Element Solutions Of Bulk Reacting Lined Ducts And Parallel-Baffle Silencers, Jundong Li

Theses and Dissertations--Mechanical and Aerospace Engineering

Lined silencers of various configurations are used to attenuate the noise from building HVAC equipment, gas turbines, and other machinery. First-mode analytical solutions are presented for sound attenuation along rectangular lined ducts, parallel-baffle silencers, and circular lined ducts. The sound absorptive lining is treated using a bulk property model. The analytical solutions entail solving a nonlinear characteristic equation in the transverse direction after the rigid-wall boundary condition is applied. The solution is compared to the boundary element solution and a local impedance analytical solution for several test cases.

A Framework And Metrics For Sustainable Manufacturing Performance Evaluation At The Production Line, Plant And Enterprise Levels, Aihua Huang

Theses and Dissertations--Mechanical and Aerospace Engineering

Sustainable manufacturing is becoming increasingly important due to scarcity of natural resources, stricter regulations and increasing customer demand for sustainable products. Sustainable manufacturing involves the use of sustainable processes and systems to produce more sustainable products. In order to meet these demands for sustainable products, manufacturing companies have to adopt numerous strategies to achieve sustainable manufacturing. The approach for evaluating sustainable products and processes have been investigated in previous work where product/process sustainability indices were proposed. However, no comprehensive methods are available for sustainable manufacturing performance evaluation at the system level. This work aims to develop two alternate methods for …

Simulation Of Horse-Fence Contact And Interaction Affecting Rotational Falls In The Sport Of Eventing, Gregorio Robles Vega

Theses and Dissertations--Mechanical and Aerospace Engineering

Rotational falls, or somersault falls, have led to serious and fatal injuries during the cross-country phase of Eventing competitions. Research to improve the safety of the sport began in 2000 after five fatal injuries occurred in the 1999 Eventing season. These efforts led to safety devices such as air jackets, improved helmets, and frangible/deformable fences. The focus of this thesis is to develop a more complete understanding of the horse-fence interaction as the approach motion transitions to a rotational fall. To achieve this, a large distribution of inertial properties was compiled through the development of a cylinder-based inertia approximation and …

Advances In Multi-Agent Flocking: Continuous-Time And Discrete-Time Algorithms, Brandon Wellman

Theses and Dissertations--Mechanical and Aerospace Engineering

We present multi-agent control methods that address flocking in continuous-time and discrete-time settings. The method is decentralized, that is, each agents controller relies on local sensing to determine the relative positions and velocities of nearby agents. In the continuous-time setting, each agent has double-integrator dynamics. In the discrete-time setting, each agent has the discrete-time double-integrator dynamics obtained by sampling the continuous-time double integrator and applying a zero-order hold on the control input. We demonstrate using analysis, numerical simulations, and experimental demonstrations that agents using the flocking methods converge to flocking formations and follow the centralized leader (if applicable).

Investigation Of An Axial Flow Rotary Valve Seal, Joseph K. Stieha

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis investigates potential materials to be used in the rotary sealing industry that provide low power loss and minimize cost. The studied rotary valve utilizes slots that act as timing valves to allow for flow axially, through the seal face, at particular times within a heat pump cycle. This investigation examines various combinations of multiple PTFE materials, plastics, and soft metals that have been proven to provide low friction coefficients. Leakage and wear requirements are stated for the future use of the rotary valve and are used to determine the effectiveness of sealing the fluid while examining the power …

Development Of A Supplier Segmentation Method For Increased Resilience And Robustness: A Study Using Agent Based Modeling And Simulation, Adam J. Brown

Theses and Dissertations--Mechanical and Aerospace Engineering

Supply chain management is a complex process requiring the coordination of numerous decisions in the attempt to balance often-conflicting objectives such as quality, cost, and on-time delivery. To meet these and other objectives, a focal company must develop organized systems for establishing and managing its supplier relationships. A reliable, decision-support tool is needed for selecting the best procurement strategy for each supplier, given knowledge of the existing sourcing environment. Supplier segmentation is a well-established and resource-efficient tool used to identify procurement strategies for groups of suppliers with similar characteristics. However, the existing methods of segmentation generally select strategies that optimize …

Impedance-To-Scattering Matrix Method For Large Silencer Analysis, Peng Wang

Theses and Dissertations--Mechanical and Aerospace Engineering

Large silencers used in the power generation industry usually have a very large cross section at the inlet and outlet. Higher-order modes will populate the inlet and outlet even at very low frequencies. Although the silencer itself is often modeled by a three-dimensional analysis tool such as the boundary element method (BEM) or finite element method (FEM), a direct computation of the transmission loss (TL) from the BEM or FEM model can be challenging without incorporating certain forms of modal expansion.

A so-called “impedance-to-scattering matrix method” is proposed to extract the modes at the inlet and outlet from the BEM …

An Efficient Heuristic To Balance Trade-Offs Between Utilization And Patient Flowtime In Operating Room Management, Feidi Dang

Theses and Dissertations--Mechanical and Aerospace Engineering

Balancing trade-offs between production cost and holding cost is critical for production and operations management. Utilization of an operating room affects production cost, which relates to makespan, and patient flowtime affects holding cost. There are trade-offs between two objectives, to minimize makespan and to minimize flowtime. However, most existing constructive heuristics focus only on single-objective optimization. In the current literature, NEH is the best constructive heuristic to minimize makespan, and LR heuristic is the best to minimize flowtime. In this thesis, we propose a current and future deviation (CFD) heuristic to balance trade-offs between makespan and flowtime minimizations. Based on …

A Transfer Matrix Approach To Determine The Low Frequency Insertion Loss Of Enclosures Including Applications, Shujian He

Theses and Dissertations--Mechanical and Aerospace Engineering

Partial enclosures are commonly used to reduce machinery noise. However, it is well known in industry that enclosures sometimes amplify the sound at low frequencies due to strong acoustic resonances compromising the performance. These noise issues are preventable if predicted prior to prototyping and production. Though boundary and finite element approaches can be used to accurately predict partial enclosure insertion loss, modifications to the model require time for remeshing and solving. In this work, partial enclosure performance at low frequencies is simulated using a plane wave transfer matrix approach. Models can be constructed and the effect of design modifications can …

Utilization Of Empirical Models To Determine The Bulk Properties Of Compressed Sound Absorptive Materials, Ruimeng Wu

Theses and Dissertations--Mechanical and Aerospace Engineering

Empirical models based on flow resistivity are commonly used to determine the bulk properties of porous sound absorbing materials. The bulk properties include the complex wavenumber and complex characteristic impedance which can be used directly in simulation models. Moreover, the bulk properties can also be utilized to determine the normal incidence sound absorption and specific acoustic impedance for sound absorbing materials of any thickness and for design of layered materials. The sound absorption coefficient of sound absorbing materials is measured in an impedance tube using wave decomposition and the measured data is used to determine the flow resistivity of the …

Investigation Of Polishing Methods And Surface Analysis After Machining Aisi 4140 Alloy Steel, Qiang Qi

Theses and Dissertations--Mechanical and Aerospace Engineering

AISI 4140 alloy steel has been a very common material to be investigated in automotive and aerospace industries for several decades. AISI 4140 alloy steel is chromium, molybdenum, and manganese containing low alloy steel. It has high fatigue strength, abrasion and impact resistance, toughness, and torsional strength. The functional performance is largely determined by the surface states after machining.

The aim of the present study is to explore the polishing methods and surface analysis after machining AISI 4140 alloy steel in different cutting speeds and cooling conditions. The surface analysis includes surface roughness, hardness and residual stresses. Compared to traditional …

Autonomous Quadrotor Collision Avoidance And Destination Seeking In A Gps-Denied Environment, Thomas C. Kirven

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis presents a real-time autonomous guidance and control method for a quadrotor in a GPS-denied environment. The quadrotor autonomously seeks a destination while it avoids obstacles whose shape and position are initially unknown. We implement the obstacle avoidance and destination seeking methods using off-the-shelf sensors, including a vision-sensing camera. The vision-sensing camera detects the positions of points on the surface of obstacles. We use this obstacle position data and a potential-field method to generate velocity commands. We present a backstepping controller that uses the velocity commands to generate the quadrotor's control inputs. In indoor experiments, we demonstrate that the …

Adaptive Multi-Objective Operating Room Planning With Stochastic Demand And Case Times, Vivek Reddy Gunna

Theses and Dissertations--Mechanical and Aerospace Engineering

The operating room (OR) is accountable for most hospital admissions and is one of the most cost and work intensive areas in the hospital. From recent trends, we discover an unexpected parallel increase in expenditure and waiting time. Therefore, improving OR planning has become obligatory, particularly regarding utilization, and service level. Significant challenges in OR planning are the high variations in demand, processing times of surgical specialties, the trade-off between the objectives, and control of OR performance in long-term. Our model provides OR configurations at a strategical level of OR planning to minimize the tradeoff between the utilization and service …

Product Disassemblability And Remanufacturability Assessment: A Quantitative Approach, Ammar Ali

Theses and Dissertations--Mechanical and Aerospace Engineering

Majority of the products get discarded at end-of-life (EoL), causing environmental pollution, and resulting in a complete loss of all materials and embodied energy. Adopting a closed-loop material flow approach can aid preventing such losses and enable EoL value recovery from these products. Design and engineering decisions made and how products are used impact the capability to implement EOL strategies such as disassembly and remanufacturing. Some underlying factors affecting the capability to implement these EOL strategies have been discussed in previous studies. However, relevant metrics and attributes are not well defined and comprehensive methods to quantitatively evaluate them are lacking. …

Binding, Protection, And Rna Delivery Properties Of Porous Silica Nanoparticles In Spodoptera Frugiperda Cells, Emily Nadeau

Theses and Dissertations--Entomology

Traditional methods of pest control are threatened by the development of insecticide resistance, both to traditional insecticides and Bt toxins. Discovery of RNA interference (RNAi) has created opportunities to develop new insect control mechanisms. However, RNAi responses appear to be robust in coleopteran pests, but other orders, e.g. Lepidoptera and Hemiptera, present varied or ineffective RNAi responses. Current delivery strategies for double-stranded RNA (dsRNA) include microinjection, ingestion, and soaking. These approaches have benefits and problems. This study investigates the potential for porous silica nanoparticles (pSNPs) to improve the delivery of dsRNA and induce an RNAi response in Spodoptera frugiperda cells. …

Assessing Stem Literacy In An Informal Learning Environment, Maureen Ann Lafemina Cavalcanti

Theses and Dissertations--Education Sciences

This mixed methods study investigated methods for assessing STEM literacy amongst middle grades students participating in an informal learning environment, specifically, a summer STEM camp. Adopting a situated perspective on STEM literacy, this dissertation employed psychometric techniques and discourse analysis to answer the overarching research question: How can STEM literacy amongst middle school students be assessed in the context of a summer STEM camp? An integrated review of literacy within and across STEM disciplines first offered a new direction for conceptualizing STEM literacy. With this understanding, subsequent research methods applied novel approaches for investigating STEM literacy in the context of …

Using Natural Language Processing And Machine Learning Techniques To Characterize Configuration Bug Reports: A Study, Wei Wen

Theses and Dissertations--Computer Science

In this study, a tool is developed that achieves two purposes: (1) given bug reports, it identifies configuration bug reports from non-configuration bug reports; (2) once a bug report is identified to be a configuration bug report, the tool finds out what specific configuration option the bug report is associated.

This study starts with a review of related works that used machine learning tools to solve software bug and bug report related issues. It then discusses the natural language processing and machine learning techniques. Afterwards, the development process of the proposed tool is described in detail, including the motivation, the …

Contributions To Edge Computing, Vernon K. Bumgardner

Theses and Dissertations--Computer Science

Efforts related to Internet of Things (IoT), Cyber-Physical Systems (CPS), Machine to Machine (M2M) technologies, Industrial Internet, and Smart Cities aim to improve society through the coordination of distributed devices and analysis of resulting data. By the year 2020 there will be an estimated 50 billion network connected devices globally and 43 trillion gigabytes of electronic data. Current practices of moving data directly from end-devices to remote and potentially distant cloud computing services will not be sufficient to manage future device and data growth.

Edge Computing is the migration of computational functionality to sources of data generation. The importance of …

Mammogram And Tomosynthesis Classification Using Convolutional Neural Networks, Xiaofei Zhang

Theses and Dissertations--Computer Science

Mammography is the most widely used method of screening for breast cancer. Traditional mammography produces two-dimensional X-ray images, while advanced tomosynthesis mammography produces reconstructed three-dimensional images. Due to high variability in tumor size and shape, and the low signal-to-noise ratio inherent to mammography, manual classification yields a significant number of false positives, thereby contributing to an unnecessarily large number of biopsies performed to reduce the risk of misdiagnosis. Achieving high diagnostic accuracy requires expertise acquired over many years of experience as a radiologist.

The convolutional neural network (CNN) is a popular deep-learning construct used in image classification. The convolutional process …

Modeling Faceted Browsing With Category Theory For Reuse And Interoperability, Daniel R. Harris

Theses and Dissertations--Computer Science

Faceted browsing (also called faceted search or faceted navigation) is an exploratory search model where facets assist in the interactive navigation of search results. Facets are attributes that have been assigned to describe resources being explored; a faceted taxonomy is a collection of facets provided by the interface and is often organized as sets, hierarchies, or graphs. Faceted browsing has become ubiquitous with modern digital libraries and online search engines, yet the process is still difficult to abstractly model in a manner that supports the development of interoperable and reusable interfaces. We propose category theory as a theoretical foundation for …

Fault Location In Transmission Systems Using Synchronized Measurements, Xiangqing Jiao

Theses and Dissertations--Electrical and Computer Engineering

Compared with conventional measurements from supervisory control and data acquisition (SCADA) system, phasor measurement units (PMUs) provide time-synchronized and direct measurements of phasors. The availability of synchronized phasor measurements can significantly improve power system protection and analysis. This dissertation is specifically committed to using synchronized measurements for estimation of fault locations in transmission systems.

Transmission lines are prone to various short-circuit faults. Accurate fault location is critical for rapid power recovery. Chapter 2 proposes a new fault location method based on sparse wide area measurements. One distinguishing feature of this method is its applicability to both transposed and untransposed transmission …

Iot Development For Healthy Independent Living, Shalom Greene

Theses and Dissertations--Electrical and Computer Engineering

The rise of internet connected devices has enabled the home with a vast amount of enhancements to make life more convenient. These internet connected devices can be used to form a community of devices known as the internet of things (IoT). There is great value in IoT devices to promote healthy independent living for older adults.

Fall-related injuries has been one of the leading causes of death in older adults. For example, every year more than a third of people over 65 in the U.S. experience a fall, of which up to 30 percent result in moderate to severe injury. …

Novel Resource Efficient Circuit Designs For Rebooting Computing, Sai Subramanya Varun Thogarcheti

Theses and Dissertations--Electrical and Computer Engineering

CMOS based computing is reaching its limits. To take computation beyond Moores law (the number of transistors and hence processing power on a chip doubles every 18 months to 3 years) requires research explorations in (i) new materials, devices, and processes, (ii) new architectures and algorithms, (iii) new paradigm of logic bit representation. The focus is on fundamental new ways to compute under the umbrella of rebooting computing such as spintronics, quantum computing, adiabatic and reversible computing. Therefore, this thesis highlights explicitly Quantum computing and Adiabatic logic, two new computing paradigms that come under the umbrella of rebooting computing. Quantum …

Stored Grain Volume Measurement Using A Low Density Point Cloud, Aaron P. Turner, Joshua J. Jackson, Nicole K. Koeninger, Samuel G. Mcneill, Michael D. Montross, Mark E. Casada, Josephine M. Boac, Rumela Bhadra, Ronaldo G. Maghirang, Sidney A. Thompson

Biosystems and Agricultural Engineering Faculty Publications

This technical note presents the development of a new apparatus and data processing method to accurately estimate the volume of stored grain in a bin. Specifically, it was developed to account for the variability in surface topography that can occur in large diameter bins when partially unloaded. This was accomplished using a laser distance meter to create a low density point cloud, from which a surface was interpolated using ArcMap geoprocessing tools. The manually controlled and portable system was designed to hold the laser distance meter and provided a common reference point. The data from the laser distance meter was …

Fourth-Generation Fan Assessment Numeration System (Fans) Design And Performance Specifications, Michael P. Sama, George B. Day, Laura M. Pepple, Richard S. Gates

Biosystems and Agricultural Engineering Faculty Publications

The Fan Assessment Numeration System (FANS) is a measurement device for generating ventilation fan performance curves. Three different-sized FANS currently exist for assessing ventilation fans commonly used in poultry and livestock housing systems. All FANS consist of an array of anemometers inside an aluminum shroud that traverse the inlet or outlet of a ventilation fan. The FANS design has been updated several times since its inception and is currently in its fourth-generation (G4). The current design iteration (FANS-G4) is reported in this article with an emphasis on the hardware and software control, data acquisition systems, and operational reliability. Six FANS-G4 …

A Method For Reflectance Index Wavelength Selection From Moisture-Controlled Soil And Crop Residue Samples, Ali Hamidisepehr, Michael P. Sama, Aaron P. Turner, Ole O. Wendroth

Biosystems and Agricultural Engineering Faculty Publications

Reflectance indices are a method for reducing the dimensionality of spectral measurements used to quantify material properties. Choosing the optimal wavelengths for developing an index based on a given material and property of interest is made difficult by the large number of wavelengths typically available to choose from and the lack of homogeneity when remotely sensing agricultural materials. This study aimed to determine the feasibility of using a low-cost method for sensing the moisture content of background materials in traditional crop remote sensing. Moisture-controlled soil and wheat stalk residue samples were measured at varying heights using a reflectance probe connected …

Evaluating A New Shade For Feedlot Cattle Performance And Heat Stress, Morgan D. Hayes, Tami M. Brown-Brandl, Roger A. Eigenberg, Larry A. Kuehn, R. Mark Thallman

Biosystems and Agricultural Engineering Faculty Publications

Heat stress in cattle results in decreased feed intake, lower daily gain, and potentially death in susceptible animals under intense conditions. A study was carried out during the summer of 2013 at the USDA-ARS U.S. Meat Animal Research Center feedlot evaluating the impact of shade on environmental conditions and cattle performance. A novel two-tiered shade was used in half of the 14 pens, each holding 30 animals. The shades were designed to reduce solar heat load by 40% to 60% and to provide traveling shade across the pen, providing varied amounts of shade area as well as varied solar reduction …

Equilibrium Moisture Content Of Kabuli, Chickpea, Black Sesame, And White Sesame Seeds, Paul R. Armstrong, Elizabeth B. Maghirang, Bhadriraju Subramanyam, Samuel G. Mcneill

Biosystems and Agricultural Engineering Faculty Publications

Sesame and chickpea are important crops in Ethiopia because both are major export crops that generate much revenue for both small farmers and the country as a whole. However, there is a lack of information about the fundamental equilibrium moisture content (EMC) relationships among these crops, which would help facilitate better monitoring and storage. Therefore, EMC adsorption and desorption prediction models based on temperature (T) and relative humidity (RH) were developed for the modified Chung-Pfost and modified Henderson models for Kabuli chickpea (KC), black sesame (BS), and white sesame (WS) seeds. The samples for conducting the adsorption and desorption tests …