Mechanical Engineering Commons^™

Evaluating Alternative Scheduling Rules To Improve Scheduling Performance, Bryan Allan White

Theses and Dissertations

In this study a powder painting production line was examined for the purpose of improving on its scheduling. A simulation model was developed to compare the performance of alternative scheduling rules. The simulation model utilized scheduling data from the original system in order to determine how accurately it represented the original system. The model was built using the discrete event simulation software Arena. The validated model was used to test a set of scheduling rules that would change the sequence in which orders in the queue were processed. By looking at the different rules and the effects on the final …

A Robot Platform For Intelligent Ground Vehicle Research, Jihang Li

Theses and Dissertations

This thesis presents a mobile platform developed for further research on the Intellegent Ground Vehicle project which began as a capstone project but without achieving full autonomy. The scope of the current project is to develop Robot Operating System (ROS) based driver libraries to the electronic system and provide application program interfaces (APIs) for higher abstraction level libraries. Prior work had provided a mechanical system and several sensors for the robot. The chassis of the vehicle is fabricated with aluminum tubings and enclosed with aluminum boards to protect internal electronics from environmental conditions. A three-wheel differential drive architecture is used …

On Phase Change Material Heat Exchangers: A Computational And Experimental Investigation, Christian Omar Rodriguez Dieppa

Theses and Dissertations

The emergence of ground- and airborne-based high energy laser (HEL) weapon systems has created a need for high-rate thermal energy storage (TES) devices that meet demanding size, weight, and power (SWaP) requirements for integration into the HEL thermal management system (TMS). Current and near-term HEL weapon systems produce thermal loads on the order of 30-300 kW when emitting, and approximately 5-10% of the peak load when in a non-emitting standby state. Emission to standby duty cycles of 10-50% are common, and therefore, sizing the TMS for real-time rejection of the peak thermal load is not practical. Accordingly, TES components can …

Haptic Shape-Based Management Of Robot Teams In Cordon And Patrol, Samuel Jacob Mcdonald

Theses and Dissertations

There are many current and future scenarios that require teams of air, ground or humanoid robots to gather information in complex and often dangerous environments, where it would be unreasonable or impossible for humans to be physically present [1-6]. The current state of the art involves a single robot being monitored by one or many human operators [7], but a single operator managing a team of autonomous robots is preferred as long as effective and time-efficient management of the team is maintained [8-9]. This is limited by the operator's ability to command actions of multiple robots, be aware of robot …

Quantification Of Frictional Drag Due To Biofouling On In-Service Ships, John Travis Hunsucker

Theses and Dissertations

The purpose of this research was to improve the quantification of frictional drag due to biofouling on in-service ships by advancing the knowledge and methodology used to study the interactions between fouling communities and the surrounding environment. This research examined the influence of hydrodynamic stress on the development and frictional drag of fouling communities that developed on a fouling release coating; investigated the reliability of using ship performance monitoring to detect changes in the hull and propeller condition; and evaluated the feasibility of developing a field deployable instrument capable of measuring the local frictional resistance on a ship hull in …

Sensitivity Studies On The Shear Lag Parameter Β Using Analytical And Numerical Techniques, George Thomas Avery

Theses and Dissertations

The strength of fiber-reinforced composites is dependent on the strength of the fiber-matrix interface bond. Thermal, chemical, and other means have been used to modify the surface of fibers, resulting in increased fiber-matrix interface bond strength. However, researchers are still dependent on empirical methods to relate surface modifications to composite performance. Additional efforts are required to develop physics-based models for micro-mechanical effects on interfacial bond strength that will be needed for the improved design and processing of fiber reinforced composites. It is anticipated that experimental, numerical, and analytical efforts will be needed to contribute toward this endeavor.

A numerical approach …

Design Maps For Fracture Resistant Functionally Graded Materials, Muhammad Ridwan Murshed

Theses and Dissertations

The objective of this research is to generate design maps to identify functionally graded microstructures with enhanced fracture toughness. Several Functionally Graded Materials (FGMs) with an edge crack and membrane loading are considered and the resulting J-integral values are computed numerically using Finite Element Analysis. In order to capture the resulting stress fields accurately, Barsoum elements are used in the vicinity of the crack tip and the simulations are carried out for several crack lengths (a) and material contrasts (κ). The averages of the J-integral values are used to determine the normalized Stress Intensity Factors which are then benchmarked with …

Fundamental Principles Of Tremor Propagation In The Upper Limb, Andrew Doran Davidson

Theses and Dissertations

Although tremor is the most common movement disorder, there exist few effective tremor-suppressing devices, in part because the characteristics of tremor throughout the upper limb are unknown. To clarify, optimally suppressing tremor requires a knowledge of the mechanical origin, propagation, and distribution of tremor throughout the upper limb. Here we present the first systematic investigation of how tremor propagates between the shoulder, elbow, forearm, and wrist. We simulated tremor propagation using a linear, time-invariant, lumped-parameter musculoskeletal model relating joint torques and the resulting joint displacements. The model focused on the seven main degrees of freedom (DOF) from the shoulder to …

Packing Sheet Materials Into Cylinders And Prisms Using Origami-Based Approaches, Jared Thomas Bruton

Theses and Dissertations

Packing sheet materials into cylinders and prisms using Origami-based approaches (Soft Origami or traditional Origami) is of interest in fields where sheet materials need folded into cylinders or prisms. Fully-dense packing has application in fields where a sheet material is to be folded with minimal gaps into a cylinder or prism. Partially-dense packing is applicable to fields where gaps are required between packed surfaces or where hollow volumes are to be filled, such as in fluid filter design. Soft Origami is explored as a method for folding soft-sheet materials into fully-dense cylinders. Two fold patterns, the "flasher'' and the "inverted-cone …

Comparing Efficacy Of Different Dynamic Models For Control Of Underdamped, Antagonistic, Pneumatically Actuated Soft Robots, Morgan Thomas Gillespie

Theses and Dissertations

Research in soft robot hardware has led to the development of platforms that allow for safer performance when working in uncertain or dynamic environments. The potential of these platforms is limited by the lack of proper dynamic models to describe or controllers to operate them. A common difficulty associated with these soft robots is a representation for torque, the common electromechanical relation seen in motors does not apply. In this thesis, several different torque models are presented and used to construct linear state-space models. The control limitations on soft robots are induced by natural compliance inherent to the hardware. This …

Position And Stiffness Control Of Inflatable Robotic Links Using Rotary Pneumatic Actuation, Charles Mansel Best

Theses and Dissertations

Inflatable robots with pneumatic actuation are naturally lightweight and compliant. Both of these characteristics make a robot of this type better suited for human environments where unintentional impacts will occur. The dynamics of an inflatable robot are complex and dynamic models that explicitly allow variable stiffness control have not been well developed. In this thesis, a dynamic model was developed for an antagonistic, pneumatically actuated joint with inflatable links.The antagonistic nature of the joint allows for the control of two states, primarily joint position and stiffness. First a model was developed to describe the position states. The model was used …

Thermal Modeling And Nanoindentation Of Shape Memory Alloy Thin Films, Mehmet Mete Ozturk

Theses and Dissertations

Metal alloys which go through a hysteric transformation due to external stimuli such as thermal and/or mechanical fields are called shape memory alloys (SMA). Thin films of SMAs have many remarkable features and have been used in the fabrication of microactuators. One potential application is a SMA thin film based information storage device. In all these applications, the existence of the strong thermomechanical coupling inherent in the phase transformation is seen. Due to coupling, knowledge of not only the mechanical field but also the thermal field is essential. The objective of this work is to study the thermal behavior of …

Modeling Atypical Building Use With Commercially Available Building Simulation Software, Sarah E. Schanck

Theses and Dissertations

National Guard armories are audited to provide recommendations for future energy reduction measures. The annual energy consumption of a New Jersey National Guard Armories cannot be modeled directly with commercially available building simulation software, due to discrepancies between the modeling capabilities of the software and the reality of the armory. A building simulation software, eQUEST, was chosen for use in this project. Discrepancies between eQUEST inputs and reality were identified and correction factors developed to minimize the effect of each discrepancy on predicted energy consumption, with the end goal of accuracy between predicted and actual energy consumption. In addition, an …

The Controlled Human Gyroscope, Randy Claude Arjunsingh

Theses and Dissertations

The objective of this thesis was to design an adaptive rotational motion simulator capable of replicating the attitudes of spacecrafts and aircrafts, while avoiding gimbal lock. Flight motion simulators are currently used for flight training and research, but there are many limitations to these existing systems. This thesis presents a low-cost design for a rotational motion platform titled, ‘The Controlled Human Gyroscope’. It uses a 4-axis system instead of the conventional 3-axis system to avoid gimbal lock and prevent the unnecessary motion of the user. The Human Gyroscope features unlimited rotation about the roll, pitch and yaw axes regardless of …

Numerical Modeling Of Soy Biodiesel To Maximize Engine Power And Efficiency While Minimizing Pollutant Emissions, Ehsan Tootoonchi

Theses and Dissertations

Biodiesel is a renewable fuel that can help to reduce dependence on foreign petroleum and to help control the negative environmental effects of combustion engines. This work develops a numerical model for soy biodiesel combustion in diesel engine applications. A comprehensive breakup model for diesel and biodiesel combustion calculations using the KIVA- 3V is presented. The primary breakup model calculates the outcome of the initial breakup stage using flow conditions, nozzle geometry, and liquid fuel characteristics, and assigns the Sauter Mean Radius (SMR) values to injecting droplets. The Kelvin-Helmholtz/Rayleigh-Taylor(KH-RT) model acts as the secondary model to break up injected particles. …

Numerical Modeling Of Heat Transfer And Material Flow During Friction Extrusion Process, Hongsheng Zhang

Theses and Dissertations

Friction extrusion process is a novel manufacturing process that converts low-cost metal precursors (e.g. powders and machining chips) into high-value wires with potential applications in 3D printing of metallic products. However, there is little existing scientific literature involving friction extrusion process until recently. The present work is to study the heat transfer and material flow phenomena during the friction extrusion process on aluminum alloy 6061 through numerical models validated by experimental measurements.

The first part is a study of a simplified process in which flow of a transparent Newtonian fluid in a cylindrical chamber caused by frictional contact with a …

Study Of Friction Extrusion And Consolidation, Xiao Li

Theses and Dissertations

Friction extrusion and consolidation was invented by The Welding Institute (Cambridge, UK) in the early 1990’s. It is related to simple extrusion processes with the primary difference being that the extrusion die rotates about the extrusion axis and the die is required to impart substantial deformation to the initially, finely divided charge (like metal waste or chips) in order to consolidate it prior to extrusion. It can produce high quality wire and fully consolidated bulk material from low-cost precursors like metal chips or powders. The advantages lie in that it is a direct method to recycle metal chips or scraps …

The Effect Of Projectile Nose Shape On The Formation Of The Water Entry Cavity, Jeremy Conrad Ellis

Theses and Dissertations

This research focuses on the effect of several convex and concave nose shapes on cavity formation for both hydrophilic and hydrophobic projectiles. It specifically investigates the effect of convex shape on the threshold velocity for cavity formation as well as the effect of concave shapes on cavity formation in terms of impact velocity, geometry of the concave shape and wettability of the projectile. For the convex cases, the streamlined axisymmetric shape significantly increases the threshold velocity when cavities form and is most pronounced for the ogive and cone. The study demonstrates that measuring the wetting angle and impact velocity is …

Non-Schmid Effects And Criteria For Dislocation Nucleation On Different Slip Systems At Grain Boundaries, Richard Durtschi Wyman

Theses and Dissertations

Criteria for grain boundary dislocation nucleation are developed. A bicrystal containing two grain boundaries is placed under varying triaxial stress states using molecular dynamics. The local resolved shear, normal, and co-slip stresses needed for grain boundary dislocation nucleation are found. A framework is developed to detect the slip system grain boundary dislocation nucleation occurs on. A survey of the different ways grain boundary dislocation nucleation occurs in the sample shows a single grain boundary can nucleate dislocations in a rich variety of ways. Using the nucleation system and resolved stress values, criteria for grain boundary dislocation nucleation on different slip …

Investigation Of Thermal Scaling Effects For A Turbine Blade Leading Edge And Pressure Side Model, Ryan A. Lynch

Theses and Dissertations

Recent experiments have attempted to quantify the overall cooling effectiveness at elevated temperature conditions. The Film Cooling Rig (FCR) at the Air Force Institute of Technology has been modified to better match the configuration of a similar large scale, low temperature rig at the Air Force Research Laboratory. This has enabled comparison and trend identification of how various properties scale from the low to high temperature condition. Various internal cooling and hole geometry configurations were investigated over a range of temperatures while utilizing the thermal scaling capability of Inconel 718. Film cooling trends and measures of overall effectiveness were matched, …

Design And Analysis Of Two Compliant Mechanism Designs For Use In Minimally Invasive Surgical Instruments, Jason Lon Dearden

Theses and Dissertations

Minimally invasive surgery (MIS) has several advantages over traditional methods. Scaling MIS instruments to smaller sizes and increasing their performance will enable surgeons to offer new procedures to a wider range of patients. In this work, two compliant mechanism-based minimally invasive surgical instrument wrist or gripper mechanisms are designed and analyzed.The cylindrical cross-axis flexural pivot (CCAFP) is a single-degree-of-freedom wrist mechanism that could be combined with existing gripper mechanisms to create a multi-degree-of freedom instrument. The simplicity of the CCAFP mechanism facilitates analysis and implementation. The flexures of the CCAFP are integral with the instrument shaft, enabling accessories to be …

Implementations Of Fourier Methods In Cfd To Analyze Distortion Transfer And Generation Through A Transonic Fan, Marshall Warren Peterson

Theses and Dissertations

Inlet flow distortion is a non-uniform total pressure, total temperature, or swirl (flow angularity) condition at an aircraft engine inlet. Inlet distortion is a critical consideration in modern fan and compressor design. This is especially true as the industry continues to increase the efficiency and operating range of air breathing gas turbine engines. The focus of this paper is to evaluate the Computational Fluid Dynamics (CFD) Harmonic Balance (HB) solver in STAR-CCM+ as a reduced order method for capturing inlet distortion as well as the associated distortion transfer and generation. New methods for quantitatively describing and analyzing distortion transfer and …

Heteromorphic To Homeomorphic Shape Match Conversion Toward Fully Automated Mesh Morphing To Match Manufactured Geometry, Robert Ivan Yorgason

Theses and Dissertations

The modern engineering design process includes computer software packages that require approximations to be made when representing geometries. These approximations lead to inherent discrepancies between the design geometry of a part or assembly and the corresponding manufactured geometry. Further approximations are made during the analysis portion of the design process. Manufacturing defects can also occur, which increase the discrepancies between the design and manufactured geometry. These approximations combined with manufacturing defects lead to discrepancies which, for high precision parts, such as jet engine compressor blades, can affect the modal analysis results. In order to account for the manufacturing defects during …

Design Of Three-Dimensional Near-Zero Refractive Index Metamaterials, David Flores Iii

Theses and Dissertations

Near-zero refractive index metamaterials exhibit remarkable electromagnetic properties which can and will be applied in the near future. From the known methods of achieving near-zero refractive index, this work primarily focuses on the design of 3D metamaterials whose permittivity and permeability are both close to zero while maintaining relatively low loss factor. The design of the metamaterials is based on the chiral shape “omega” and designed to weave periodically as a fishnet. Theoretical analysis, computer modeling and simulation are steps taken in the design of metamaterials. A computational tool based on the robust method for effective parameter extraction is successfully …

Automatic Dependent Surveillance-Broadcast For Detect And Avoid On Small Unmanned Aircraft, Matthew Owen Duffield

Theses and Dissertations

Small unmanned aircraft systems (UAS) are rapidly gaining popularity. As the excitement surrounding small UAS has grown, the Federal Aviation Administration (FAA) has repeatedly stated that UAS must be capable of detecting and avoiding manned and unmanned aircraft. In developing detect-and-avoid (DAA) technology, one of the key challenges is identifying a suitable sensor. Automatic Dependent Surveillance-Broadcast (ADS-B) has gained much attention in both the research and consumer sectors as a promising solution. While ADS-B has many positive characteristics, further analysis is necessary to determine if it is suitable as a DAA sensor in environments with high-density small UAS operations. To …

Error Propagation Dynamics Of Piv-Based Pressure Field Calculation, Zhao Pan

Theses and Dissertations

Particle Image Velocimetry (PIV) based pressure field calculation is becoming increasingly popular in experimental fluid dynamics due to its non-intrusive nature. Errors propagated from PIV results to pressure field calculations are unavoidable, and in most cases, non-negligible. However, the specific dynamics of this error propagation process have not been unveiled. This dissertation examines both why and how errors in the experimental data are propagated to the pressure field by direct analysis of the pressure Poisson equation. Error in the pressure calculations are bounded with the error level of the experimental data. The error bounds quantitatively explain why and how many …

Thermal Conductivity Measurements Of Nanomaterials, Javier Acosta Martinez

Theses and Dissertations

Thermal conductivity “k” can be defined as a material property where heat is diffused due to a temperature gradient within the material. Among the applications for thermal conductivity are: thermoelectrics, thermal interface materials, thin films, insulation, among many others. A study was made to compare the different types of studies of thermal conductivity of nanomaterials, as well as, a comparison among the different types of setups used to measure thermal conductivity. For this study a custom made thermal conductivity tester was built, this tester was validated by measuring materials with both low and high thermal conductivity, and comparing the results …

Nonlinear Dynamics Of Electrostatically Actuated Nanotweezers, Bin Liu

Theses and Dissertations

Bin Liu, Nonlinear Dynamics of Electrostatically Actuated Nanotweezers. Master of Science (MS), May 2016, 77 pp, 6 tables, 59 figures, references, 25 titles. The amplitude-frequency response of electrostatic nanotube nanotweezer device system is investigated; soft alter current was setting at near half natural frequency impulse on nanotubes which are referred to as two arms, parametric and primary resonances will be shown in the results, respectively. Firstly we are using the Method of Multiple Scales (MMS) analytical model; results will be compared with Reduced Order Model (ROM). By variation and comparison of multiple parameters including van der wall molecular forces, electrostatic …

Graphene-Based Nanomaterials For Hydrogen Generation And Storage, Lin Wei

Theses and Dissertations

Hydrogen energy is promising candidate to replace fossil fuel. However, the usage of hydrogen energy was greatly limited due to its generation and storage. In this thesis report, the author synthesized novel metal/carbon nanomaterials used for the hydrogen storage and hydrogen evolution reaction. These materials were characterization by XRD, Raman, XPS, SEM, EDX, etc. And the surface area and the hydrogen storage properties were tested by ASAP 2020, using the BET measurement and hydrogen isotherm curves to discuss the gas adsorption properties. As for hydrogen evolution reaction, the materials were made into electrodes and tested with LSV, CV to shows …

Computing Research In Academia: Classifications, Keywords, Perceptions, And Connections, Sung Han Kim

Theses and Dissertations

The Association for Computing Machinery (ACM) recognizes five computing disciplines: Computer Science (CS), Computer Engineering (CE), Information Technology (IT), Information Systems (IS), and Software Engineering (SE). Founded in 1947 the ACM is the world's largest society for computing educators, researchers, and professionals. While Computer Science has been a degree program since 1962, the other four are relatively new. This research focuses on understanding the graduate research in four of the five ACM disciplines (CS, CE, IT, and IS) using a large body of thesis and dissertation metadata. SE is not found in the metadata and graduate work in SE is …