Mechanical Engineering Commons^™

Atmospheric Microbial Community Sampling System For Varying Altitude Collection, Kenneth David Domingue

Masters Theses

The study of airborne microbial communities in the vertical atmosphere is an area of research in which very little data has been collected and analyzed. Developing a vehicle to house biological sampling equipment that collects, and mitigates contamination is required by a team of biology researchers to perform sampling of atmospheric microbial communities. This study uses a sampler box that is attached to aerostatic vehicles: zero pressure balloons and tethered balloon/kite structures. Zero pressure balloons are used for sampling at altitudes above 150 m above sea level, and tethered balloon/kite structures are used for sampling at 30 m and 150 …

Cyber-Physical System Characterization And Co-Regulation Of A Quadrotor Uas, Seth E. Doebbeling

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

An Unmanned Aircraft System (UAS) is a Cyber-Physical System (CPS) in which a host of real-time computational tasks contending for shared resources must be cooperatively managed to obtain mission objectives. Traditionally, control of the UAS is designed assuming a fixed, high sampling rate in order to maintain reliable performance and margins of stability. But emerging methods challenge this design by dynamically allocating resources to computational tasks, thereby affecting control and mission performance. To apply these emerging strategies, a characterization and understanding of the effects of timing on control and trajectory following performance is required. Going beyond traditional control evaluation techniques, …

Meshless Method For Simulation Of Compressible Flow, Ebrahim Nabizadeh Shahrebabak

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the present age, rapid development in computing technology and high speed supercomputers has made numerical analysis and computational simulation more practical than ever before for large and complex cases. Numerical simulations have also become an essential means for analyzing the engineering problems and the cases that experimental analysis is not practical. There are so many sophisticated and accurate numerical schemes, which do these simulations. The finite difference method (FDM) has been used to solve differential equation systems for decades. Additional numerical methods based on finite volume and finite element techniques are widely used in solving problems with complex geometry. …

Heat Transfer Analysis Of Localized Heat-Treatment For Grade 91 Steel, Jacob D. Walker

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many of the projects utilizing Grade 91 steel are large in scale, therefore it is necessary to assemble on site. The assembly of the major pieces often requires welding in the assembly; welding drastically changes the superior mechanical properties of Grade 91 steel that it was specifically developed for. Therefore, because of the adverse effects of welding on the mechanical properties of Grade 91, it is necessary to do a localized post weld heat treatment.

In this study a localized post weld heat treatment is used to gather experimental data. The data is then used to derive unknown heat transfer …

Analysis Of Angles-Only Hybrid Space-Based/Ground-Based Approach For Geosynchronous Orbit Catalog Maintenance, Blythe A. Andrews

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Geosynchronous Equatorial Orbit (GEO) is critical to Earth communications, weather monitoring, and national defense. Orbit estimation of GEO objects is difficult due to physical constraints placed on ground-based tracking devices such as weather, object range, and tracking frequency restrictions. These constraints are commonly mitigated through the use of two-way signaling devices for cooperative GEO satellites. However, determining the position and velocity of uncooperative GEO satellites and/or objects is more challenging. The objective of this dissertation is to quantify the increased orbital accuracy of objects in the GEO catalog when the Air Force Space Command Space Surveillance Network (AFSPC SSN) is …

Three-Dimensional Printing Of "Green" Fuels For Low-Cost Small Spacecraft Propulsion Systems, Stephen A. Whitmore

Mechanical and Aerospace Engineering Faculty Publications

This paper details the advantages of employing modern additive manufacturing methods to fabricate hybrid rocket fuels for intrinsically safe and green small spacecraft propulsion systems. Using additive manufacturing overcomes multiple issues frequently associated with hybrid propulsion, including poor volumetric efficiency, system ignitability, and low fuel regression rates. When certain three-dimensionally printed thermoplastics are subjected to a high-voltage low-wattage charge, electrostatic arcing along the surface pyrolizes a small amount of material that, with the introduction of an oxidizer, “seeds” combustion and produces immediate and reliable ignition. Thermoplastic fuel grains can be printed with port shapes that enhance burn properties and increase …

Structural Vs.. Compositional Disorder In Thermal Conductivity Reduction Of Sige Alloys, Jihui Nie, Raghavan Ranganathan, Zhi Liang, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We Use Equilibrium Molecular Dynamics Simulations to Determine the Relative Role of Compositional and Structural Disorder in a Phononic Thermal Conductivity Reduction by Studying Three 50-50 SiGe Alloy Structures: Ordered Alloys, Disordered Alloys, and Amorphous Alloys, as Well as Pure Amorphous Si and Ge Structures for Reference. While Both Types of Disorders Significantly Reduce Thermal Conductivity, Structural Disorder is Much More Effective to This Aim. the Examination of Phonon Lifetimes in Disordered Alloys Shows High Values in a Low Frequency Regime Governed by Umklapp Scattering that Are Reduced Rapidly with Increasing Frequency Following Rayleigh Scattering Behavior. the Local Properties Analysis …

Design And Analysis Of Adaptive Control Systems Over Wireless Networks, Ali Albattat, Benjamin Gruenwald, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we study the design and analysis of adaptive control systems over wireless networks using event-triggering control theory. The proposed event-triggered adaptive control methodology schedules the data exchange dependent upon errors exceeding user-defined thresholds to reduce wireless network utilization and guarantees system stability and command following performance in the presence of system uncertainties. Specifically, we analyze stability and boundedness of the overall closed-loop dynamical system, characterize the effect of user-defined thresholds and adaptive controller design parameters to the system performance, and discuss conditions to make the resulting command following performance error sufficiently small. An illustrative numerical example is …

Novel Layered Double Hydroxides-Hydroxyapatite/Gelatin Bone Tissue Engineering Scaffolds: Fabrication, Characterization, And In Vivo Study, Fateme Fayyazbakhsh, Mehran Solati-Hashjin, Abbas Keshtkar, Mohammad Ali Shokrgozar, Mohammad Mehdi Dehghan, Bagher Larijani

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Developing Porous Biodegradable Scaffolds through Simple Methods is One of the Main Approaches of Bone Tissue Engineering (BTE). in This Work, a Novel BTE Composite Containing Layered Double Hydroxides (LDH), Hydroxyapatite (HA) and Gelatin (GEL) Was Fabricated using Co-Precipitation and Solvent-Casting Methods. Physiochemical Characterizations Showed that the Chemical Composition and Microstructure of the Scaffolds Were Similar to the Natural Spongy Bone. Interconnected Macropores Ranging over 100 to 600 Μm Were Observed for Both Scaffolds While the Porosity of 90 ± 0.12% and 92.11 ± 0.15%, as Well As, Young's Modulus of 19.8 ± 0.41 and 12.5 ± 0.35 GPa Were …

Development Of The Compact Jet Engine Simulator From Concept To Useful Test Rig, Henry H. Haskin

Mechanical & Aerospace Engineering Theses & Dissertations

NASA had a goal to develop a set of modeling tools for designing next generation civil transport aircraft with reduced noise, emissions and increased fuel efficiency by 2016. To verify the models, a database of aerodynamic and acoustic data was needed for an unconventional flying wing design that was predicted to meet the goals. A Compact Jet Engine Simulator (CJES) was needed as the jet source for the 5.8% scale model. Ultra-Compact Combustor Technology from the Air Force Research Laboratory was used to reduce the conventional burner acoustic test rigs down to the required scale size. The Air Force design …

A Low Cost Inflatable Cubesat Drag Brake Utilizing Sublimation, Adam Charles Horn

Mechanical & Aerospace Engineering Theses & Dissertations

The United Nations Inter-Agency Debris Coordination Committee has adopted a 25-year post-mission lifetime requirement for any satellite orbiting below 2000 km in order to mitigate the growing orbital debris threat. Low-cost CubeSats have become important satellite platforms with startling capabilities, but this guideline restricts them to altitudes below 600 km because they remain in orbit too long. In order to enable CubeSat deployments at higher release altitudes, a low-cost, ultra-reliable deorbit device is needed.

This thesis reports on efforts to develop a deployable and passively inflatable drag brake that can deorbit from higher orbital altitudes, thereby complying with the 25-year …

Investigation, Modeling And Validation Of Digital Bridge For A New Generation Hot-Wire Anemometer, Karthik Kamalakar Joshi

Mechanical & Aerospace Engineering Theses & Dissertations

The Digital Bridge Thermal Anemometer (DBTA) is a new generation anemometer that uses advanced electronics and a modified half-Wheatstone bridge configuration, specifically a sensor and a shunt resistor in series. This allows the miniaturization of the anemometer and the communication between host computer and anemometer is carried out using serial or ethernet which eliminates the noise due to the use of long cables in conventional anemometer and the digital data sent to host computer is immune to electrical noise. In the new configuration the potential drop across a shunt resistor is used to control the bridge.

This thesis is confined …

Validation Of Adaptive Control Laws Using Optimization And Trajectory Sensitivity, Mario Luca Fravolini, Antonio Ficola, Fabio Radicioni, Tansel Yucelen, Ehsan Arabi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper it is proposed an easy-to-use verification and validation method for adaptive control laws that relies on time domain simulations. The problem is set as a trajectory falsification problem that is the search of closed loop trajectories that, starting from a set of admissible initial conditions, reach a set of unsafe states. The falsification is placed as a nonlinear optimization problem whose decision variables are the initial condition of the states and the uncertain parameters of the system. The falsification is performed iteratively using the local gradient of the sensitivity function derived from a linearized model of the …

A Decentralized Adaptive Control Architecture For Large-Scale Active-Passive Modular Systems, Benjamin C. Gruenwald, Ehsan Arabi, Tansel Yucelen, Animesh Chakravarthy, Drew Mcneely

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Decentralized control of large-scale active-passive modular systems is considered. These systems consist of physically interconnected and generally heterogeneous modules, where local control signals can be only applied to a subset of these modules (i.e., active modules) and the rest are not subject to any control signals (i.e., passive modules). Using a set-theoretic adaptive control approach predicated on restricted potential functions, we design decentralized command following control architectures for each active module such that they can effectively perform their tasks with strict performance guarantees in the presence of unknown physical interconnections between modules and module-level system uncertainties. The efficacy of the …

An Algorithm For Enlarging The Region Of Attraction Using Trajectory Reversing, Nilay Kant, Dhrubajit Chowdhury, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Trajectory reversing is a method commonly used for estimating the region of attraction of stabilized equilibria. Using a discrete set of points obtained by trajectory reversing, this paper presents an algorithm for estimation and mathematical representation of the region of attraction using convex hulls. Several two-dimensional examples are presented to illustrate the usefulness of the algorithm. The method provides larger estimates compared to that obtained by existing algorithms, but its main advantage lies in its applicability to higher-order systems. The mathematical representation of the region of attraction is useful in applying the Impulse Manifold Method, which was developed for stabilization …

Enlarging The Region Of Attraction Of Equilibria Of Underactuated Systems Using Sum Of Squares And Impulse Manifold Method, Dhrubajit Chowdhury, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents an algorithm to enlarge the estimate of the Region of Attraction of stable equilibria of underactuated systems. To achieve this, we use a combination of the Sum of Squares (SOS) method and the Impulse Manifold Method (IMM). Initially, the SOS method is used to optimize the control input u(x) in order to obtain an enlarged Region of Attraction. The IMM is then applied on enlarged Region of Attraction obtained using SOS to further enlarge it. The IMM is implemented using high gain feedback and to demonstrate the efficacy of our algorithm, we present simulation results where an …

Swing-Up Of The Inertia Wheel Pendulum Using Impulsive Torques, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The swing-up control problem of the inertia wheel pendulum is revisited in this paper. As different from existing methods, purely impulsive control inputs are used for swing-up. A mathematical formulation of the problem indicates that swing-up can be achieved using impulsive inputs applied at two discrete time instants. Two different swing-up schemes are presented and validated using numerical simulations where the impulsive inputs are approximated by high-gain feedback. The results of numerical simulations establish a direct link between high wheel velocities during swing-up and control strategies that take the pendulum directly to the upright configuration. They also indicate that the …

Jfs Turbine Engine For Cal Poly Mechanical Engineering Department, Dorian Capps, Zoe Kai Tuggle

Mechanical Engineering

This project concerns the development of a gas turbine engine laboratory activity for use in one of Cal Poly’s technical elective courses in the Mechanical Engineering Department, ME 444: Combustion Engine Design. The class is taught by Dr. Patrick Lemieux, who is also in charge of the on-campus engines lab where the turbine engine will be installed. The engine itself is a JFS-100-13A turboshaft engine that will be coupled to an electric dynamometer inside of the dyno test cell. Students taking the ME 444 class, likely starting in Winter Quarter of 2018, will be able to perform hands-on experiments using …

Leading Edge Boundary Layer Suction Device For The Cal Poly Rolling Road Wind Tunnel, Daniel C. Glover, Liam M. Madden, Robert J. Cabri

Mechanical Engineering

Over the course of three quarters from Fall of 2016 to Spring of 2017, our team designed and built a boundary layer suction device. The boundary layer suction device has three main functions: a scoop that redirects most of the boundary layer air out of the wind tunnel, fans that suck the remaining boundary layer air through a porous plate and ducting and out of the wind tunnel, and a transition bridge that transitions the remaining air smoothly onto the rolling road. The wind tunnel is owned by Cal Poly and the rolling road is a new addition to it. …

Deployable Antenna For Cubesat, Mackenzie Thomas Lennon, Caleb Andrew Barber, David Matthew Galves

Mechanical Engineering

This project is a proof-of-concept ground model of a large deployable antenna designed for the small space requirements of CubeSats. This small deployment module is designed to fit a 2 m by 1 m reflective antenna inside a storage volume of with the dimensions 20 cm by 20 cm x 40 cm. The reflector will be deployed to a parabolic shape with the goal of modeling the reflector necessary for high frequency communication. Because this module is designed as a proof-of-concept for the deployable parabolic reflector specifically, no electrical components will be incorporated and will just focus on the deployment …

Gain Scheduling Controller For Aircraft With Mass And Inertia Variation, Eunyoung Kim

Mechanical and Aerospace Engineering Dissertations - Archive

Robustness is one of the main control design requirements for aircraft control.Robustness is sought in the stability and performance of closed loop system against various factors such as disturbance, measurement error, modeling error or un-modeled dynamics. In aircraft control design, it is common to assume that the mass and inertia properties of aircraft are constant. Further, aircraft is assumed to have symmetry inits mass distribution relative to its mid-vertical plane. There are, however, cases where the aircraft mass changes rapidly, most notably in aerial refueling operation.The mass change also results in changes in the inertia matrix. An aircraft may also …

On Space Program Planning: Quantifying The Effects Of Spacefaring Goals And Strategies On The Solution Space Of Feasible Programs, Mark Douglas Coley

Mechanical and Aerospace Engineering Dissertations - Archive

An organization's space program represents the coalescence of top-level goals and strategies with the specific, lower-level combinations of mission architectures, hardware, and technology. High costs and long lead times necessitate substantial planning and key decisions to be made years, possibly decades, in advance. Unfortunately, the methods and processes available for planning have historically been unable to provide decision-makers with objective, quantitative information from both the top and lower levels of the space program. Instead, decision-makers are forced to turn to top-level, qualitative assessments, disconnected from any of the fundamental, technical details, where inconsistent comparisons and secondary effects often become the …

Studying Effects Of Adhesive Layer On Electrical Signals Of Piezoelectric Transducer Bonded With Structure, Md Mazharul Islam

Mechanical and Aerospace Engineering Dissertations - Archive

Piezoelectric wafer active sensors (PWAS) are the most attractive transducers for guided-wave or ultrasound based structural health monitoring (SHM) because of their light weight and compact size. In order to excite guided waves in a structure, the PWASs are usually bonded on the surface of the structure by adhesive materials. The electrical signal applied to the surface bonded PWAS is converted to mechanical deformation of the PWAS which in turn is transferred to the structure through the adhesive layer. Thus, understanding the effects of the adhesive layer on the electrical response of the PWAS enables us to optimize the mechanical …

Nonlinear Model Predictive Control For Cooperative Control And Estimation, Pengkai Ru

Mechanical and Aerospace Engineering Dissertations - Archive

Recent advances in computational power have made it possible to do expensive online computations for control systems. It is becoming more realistic to perform computationally intensive optimization schemes online on systems that are not intrinsically stable and/or have very small time constants. Being one of the most important optimization based control approaches, model predictive control (MPC) has attracted a lot of interest from the research community due to its natural ability to incorporate constraints into its control formulation. Linear MPC has been well researched and its stability can be guaranteed in the majority of its application scenarios. However, one issue …

Characterization Of Vertically Split Distribution-Wet Cooling Media Used In Data Centers, Mullaivendhan Varadharasan

Mechanical and Aerospace Engineering Theses - Archive

Data Centers houses substantial number of information technology (IT) equipment like computer servers and storage modules associated with various electronic components which consume high volume of electricity. The IT equipment in data center housing keeps dissipates heat energy as it is constantly running day and night. To keep the data center environment under thermally control and to favor the reliability of electronic components, we need to adopt a cooling technique which aids the module level cooling, with due consideration of the size of the data center and its geographical location. One of the adopted cooling technique in data center thermal …

Composite Plate Optimization With Structural And Manufacturing Constraints, Deepak Polaki

Mechanical and Aerospace Engineering Theses - Archive

This is a design optimization study that focuses on the value of free size optimization technology on composite structures which incorporates realistic structural requirements and practical manufacturing limitations to achieve an iterative design with effective structural performance. To detail a study on such practical implementation, a sample structure is required. A rectangular composite laminate with a central hole cutout is considered for this study and is designed using finite elemental tools which includes compression, tension and shear loading conditions with load reactions at bolted joints and buckling stability. Free size optimization and size optimization are used in this study to …

Reliability Assessment Of Solder Joint Using Bga Package – Megtron 6 Versus Fr4 Printed Circuit Boards, Mugdha Anish Chaudhari

Mechanical and Aerospace Engineering Theses - Archive

When it comes to the mechanical and electrical seam of the Printed Circuit Board (PCB) and package, reliability of the board plays a major impact on PCB. As the frequency increases, losses in signals increase. This necessitates the use of new materials for such applications. Nelco 4000-13EPSI, Rogers 4350B, Panasonic Megtron 6 are few high-speed materials used. Studies have shown that Megtron 6 has the least dielectric losses so far, low transmission loss, high heat resistance and has low weight loss than the FR-4 boards. With an increasing demand for high performance, reliability and lower costs, the field of electronic …

Solder Joints Design Optimization Of Qfn Packages For Different Boards By Investigating Solder Joint Reliability, Rishikesh Vilas Tendulkar

Mechanical and Aerospace Engineering Theses - Archive

Quad Flat No-lead package (QFN) is one of the most cutting-edge technologies emerged in the market, exhibiting high performance and efficiency with unparalleled cost effectiveness. QFN, a leadless package, is an ideal choice for applications where size, weight thermal and electrical characteristics are critical, particularly in mobile and handheld devices. Applications like automotive, defense and high current circuits require the package to be mounted on thick printed circuit boards (PCB). The motivation of this work is to understand the effect of design variations of solder joints affecting reliability and optimize the solder package to improve reliability for application on different …

An Improved Method For Measurement Of Radial Thermal Conductivity Of Cylindrical Bodies, Salwa Shaik

Mechanical and Aerospace Engineering Theses - Archive

Li-ion cells are ubiquitously found in day to day electronic devices due to their high power density storage capacity. These batteries are known to exhibit sharp reduction in performance at high temperature. Due to this, several attempts have been made in the past to measure thermal properties of the Li-ion cell. This work improves upon past measurements by showing that heat loss during measurements is non-negligible, and by developing an analytical model to account for such heat loss. Experimental measurements carried out on multiple materials demonstrate non-negligible heat loss. When accounted analytically, these data result in thermal conductivity values that …

Electro-Pneumatic Shifting And Servo Control Of A Clutch For A Fsae Racecar, Rahul Janardhan Chalmela

Mechanical and Aerospace Engineering Theses - Archive

FSAE is an international student design competition held by SAE International where students design, build and compete in static events like cost, design and dynamic events ranging from acceleration, autocross to endurance. UTA Racing has been a part of FSAE since 1982 and have been using a mechanical design for their shifter and clutch since then. This year for the 2017 design competition an electro-pneumatic system is developed to replace the mechanical system. This system consists of pneumatic cylinders controlling a sequential shifter and a servo clutch. The cylinders are controlled using direction control valves, these receive their signals from …