Engineering Commons^™

Trend Significance Levels Of Rain Onset And Cessation And Lengths Of The Wet And Dry Seasons In Epe, Lagos State, Nigeria, Adekunle Adedeji Alli, Olorunwa Eric Omofunmi

Makara Journal of Technology

This study aims to reduce crop failure resulting from a dry spell, which is the first occurrence of unsustainable rainfall that deceives farmers into planting. Thus, trends need to be tested using hypothesis, kurtosis, and other statistics to analyze the risks associated with unstable planting calendars and their possible mitigation strategies. The daily rainfall data from 1982 to 2018 were obtained from the archive of NASA/POWER SRB/FLASH, and the research location is Epe, Lagos State, Nigeria, which lies at latitude 6.585° N and longitude 3.962° E. Microsoft Excel was used to perform the tests. Results show that the null hypothesis …

Mechanical Engineering News, Georgia Southern University

Mechanical Engineering: News & Publications (2013-2023)

• Department Hosts Summer Camp for HS Students

An Engineer's Guide To Periodic Discrete Wavelet Transforms And The Periodic Wavelet Balance Method, Simon Jones

Faculty Publications - Mechanical Engineering

This Technical Report aims to explain how to apply the discreteWavelet Balance Method (dWBM) for solving periodic differential equations using periodized Daubechies wavelets. The primary goal is to provide the user sufficient details to implement the technique without extensive mathematical background.

Chapter 2 of this document reviews the discrete Fourier transform using a multivariate regression approach, followed by a review of the discrete Harmonic Balance Method (dHBM) for approximating solutions to periodic differential equations. It is important the reader complete this chapter, even if they are familiar with the topics, since the approaches demonstrated in Chapter 2 with harmonic functions …

Effect Of Temperature On Abrasion Erosion In Particle Based Concentrating Solar Powerplants, Nipun Goel, Tessa Mei-Lin Fong, John P. Shingledecker, Andrew Russell, Michael W. Keller, Siamack A. Shirazi, Todd Otanicar

Mechanical and Biomedical Engineering Faculty Publications and Presentations

The use of solid particles as a heat transfer medium is being explored for concentrated solar power plants (CSP) to increase their efficiency by achieving operating temperature >700 °C. During operation, these hot particles are expected to move along the various components within the collector system, resulting in material degradation from a combination of high-temperature oxidation and erosion. In the present study, the performance of candidate materials was evaluated through a series of abrasion erosion experiments at room temperature as well as at 800 °C. Wear in metallic and refractory type materials was investigated using CarboBead® HSP 40/70 particles inside …

Stress Analysis Of Functionally Graded Materials, Nilabh Krishna

Mechanical and Aerospace Engineering Dissertations - Archive

A functionally graded material (FGM) is an inhomogeneous material whose material properties vary continuously. Since FGM’s material properties are continuous at the interface of the two materials, unlike conventional composites whose material properties are discontinuous at the interface, it is best suited to prevent catastrophically failure, stress concentration, and residual stresses. Literature reviews revealed that most of the research on FGMs was a 2-D analysis, especially on FGM plates and beams. This research focuses on 3-D stress analysis for an elastic medium that contains a spherical inclusion made of an FGM embedded in a matrix phase. To the best of …

Effect Of Thermal Conductivity, Reynolds Number, Aspect Ratio And Packing Arrangement On Radial Heat Transfer In Packed Beds, Nishith Gorla

Mechanical and Aerospace Engineering Dissertations - Archive

The key motivation for this research is to study heat transfer developments in packed beds. The radial heat transfer enhancement of a packed bed in the laminar flow region is one of the major areas of ongoing research in mechanical, aerospace and chemical industries, especially the response of a packed bed during conjugate heat transfer with the fluid-solid interaction. This computational study focuses on the impact of packing size, thermal conductivity, and arrangement on the radial heat transfer performance as a function of Reynolds number. A simple annular tube packed with circles (2D) and spheres (3D) is utilized for this …

Modeling The Effect Of In Situ Nozzle-Integrated Compression Rolling On The Mechanical And Fracture Behavior Of Fused Filament Fabrication (Fff) 3d Printed Parts, Momen Mohammad Qasaimeh

Mechanical and Aerospace Engineering Dissertations - Archive

Fused filament fabrication (FFF) is one of the most common additive manufacturing/3D printing techniques where continuously extruded semi-molten filaments are deposited in a layer-by-layer manner. The quality of the manufactured part depends on some major factors such as filament-filament contact and adhesion as well as the void fraction. Filament to filament adhesion affects the part strength under transverse load. In our earlier work, we studied the effect of in situ ball rolling on the thermal and mechanical properties of the printed parts. It was found that when printing/rolling parameters are correctly tuned and in situ compression rolling is appropriately applied …

Set-Theoretic Frameworks For Online Optimization, Estimation, And Control, Dignata Bhattacharjee

Mechanical and Aerospace Engineering Dissertations - Archive

This research is primarily focused on developing online frameworks, which are suited to real-time implementation, for performance optimization, estimation, and control of dynamical systems using set-theoretic concepts and/or having set-theoretic interpretations. First, two perturbation-based extremum seeking control schemes, based on the classical setup and equipped with novel adaptation laws for the perturbation signal amplitudes, are proposed for general single input single output nonlinear systems. The proposed schemes are able to extremize steady-state system output in a practical asymptotic sense, i.e., the system is driven to an arbitrarily small set centered at the true steady-state optimal operating point. The next development …

Uncertainty Propagation, Control, And Estimation Of Stochastic Dynamic Systems Using Generalized Polynomial Chaos Expansion, Rajnish Bhusal

Mechanical and Aerospace Engineering Dissertations - Archive

In recent years, uncertainty propagation has emerged as an important research area in the field of dynamical systems. The growing interest in this area arises out of the need to develop computationally efficient approaches to predict the evolution of a system subject to uncertainties. To this end, this dissertation is focused on developing computational frameworks for uncertainty propagation, control, and state estimation of stochastic dynamical systems using the generalized polynomial chaos (gPC) expansion technique. In the first part of this dissertation, the construction of gPC expansion is presented in general. The novelty of this dissertation lies in developing a mixed …

Computational Investigation Of Energy Dissipation Through Progressive Failure In Tailored Composite Structures Via Explicit Finite Element Analysis, Anirudh Srinivas

Mechanical and Aerospace Engineering Dissertations - Archive

In this study, energy dissipation in structures implementing a previously developed, analytically modeled, and experimentally validated composite tailoring concept is investigated using an explicit finite element approach. The tailored composite structures consist in a series connection of parallel alternate load paths of tailored length and thickness. The advantage of the tailored structure when compared to an untailored conventional structure is that when subjected to a tensile load, the response of the tailored composite structure is characterized by progressive failure of the load paths resulting in increased energy dissipation. The tailored composite structure is modeled for IM7-8552 composite material using a …

Laminar Swept And Cross Shockwave/Boundary-Layer Interactions, Jiss Jacob Sebastian

Mechanical and Aerospace Engineering Dissertations - Archive

Shockwave/boundary-layer interactions are considered one of the most complex problems in high-speed gas dynamics, and numerous studies have been carried out for more than eighty years to understand the fundamental physics. A numerical study was performed using fin-plate configurations to study the three-dimensional swept and cross shockwave/ laminar boundary-layer interactions. All the interactions studied were strong enough for the boundary layer to separate. In the first part, swept shock interactions between a laminar boundary layer and the shockwave induced by a sharp fin mounted perpendicularly on a flat plate were studied. Different flow conditions were investigated at freestream Mach numbers …

Design, Operation And Maintenance Of Direct And Indirect Evaporative Cooling Systems In Data Center Thermal Management, Ashwin Siddarth

Mechanical and Aerospace Engineering Dissertations - Archive

Evaporative cooling is an alternative data center cooling solution that presents significant energy cost savings in acquisition and operation when compared to conventional air conditioning and mechanical refrigeration systems. This research focuses on developing a deeper understanding in implementing, operating and maintaining evaporative cooling systems integrated with air-side economization to realize the energy savings potential in data center cooling. The goal of the research is to develop a comprehensive guide to assess and contrast different approaches of evaporative cooling being used in data center cooling and provide guidance in improving water and energy efficiency. An air handling unit (AHU) serves …

Design Of Streamline-Traced Inlets And Their Integration With Rotating Detonation Engines, Malcolm Lee Branch

Mechanical and Aerospace Engineering Theses - Archive

This thesis has two parts: 1) design of the streamline-traced inlets (STIs); and 2) integration of STIs with rotating detonation engines (RDEs). The STI design starts with a two-dimensional, isentropic compression flowfield as the parent flowfield. The method of characteristics was used to generate the flowfield throughout the entire STI. For a given flight altitude 18 km, freestream Mach number M?=3.0, and inlet exit-plane Mach number M?=1.2, a parametric sweep of the initial deflection angle ?1=4.0--11.0 deg and the Mach number at the entrance of the internal compression system M3=1.3--1.7 was performed to determine the STI performance sensitivity as a …

Haptic Interface Optimization For Virtual Anastomosis Surgery Training, Kangji Huang

Mechanical and Aerospace Engineering Theses - Archive

Virtual anastomosis surgery study allows surgeons to perform or practice suturing in virtual reality using a commercial haptic device. The haptic device can generate force feedback so that the user can feel the real touch sensation of the object in virtual reality. The virtual anastomosis surgery study has two requirements which are that the haptic device must be fixed on the operating table and haptic device location must be suitable for different surgeons. The goal is to use a commercially available haptic device for this purpose, rather than design a new device for each possible surgery that must be performed. …

Design And Cfd Analysis Of Bimetallic Based Passive Dynamic Cold Plate For High Power Direct-To-Chip Liquid Cooling, Apurv Pravin Deshmukh

Mechanical and Aerospace Engineering Theses - Archive

Rising demand for high-performance chips results in the need for advanced and efficient cooling technologies like direct to chip liquid cooling. Cold plates based utilizing direct liquid cooling is one of the most efficient and the most investigated cooling technology since the 1980s. Major data services and cloud providers like IBM, Microsoft, and Google had already started a shift towards liquid-cooled data centers for their high computational servers. At the chip level nowadays, the processors are divided into several cores and each of these cores continuously works at varying computational demands. This creates a non-uniform heat distribution across the processor, …

Simulation Of A Soft Body Non-Grasp Manipulator Using A Spring-Mass-Damper Cloth Model, Cristian Almendariz

Mechanical and Aerospace Engineering Theses - Archive

Simulation and modeling are well known and important tools in the field of robotics, being used to validate design and in the development of robotic control systems. Traditionally, robotic systems have been primarily rigid body systems and used in well controlled environments where interactions are highly predictable, and exceptions are minimized. With the ever-increasing adoption of robotics in the medical field, typical robotic environments are becoming highly unpredictable and requiring the modeling and simulation of not only rigid body systems but soft systems and interactions between the two. This work addresses model improvement of a “soft and hard” robotic system …

Development Of Virtual Simulation For Evaluation Of Robotic Assistive Environment, Shubham Raosaheb Gunjal

Mechanical and Aerospace Engineering Theses - Archive

Robotics research in virtual simulation has the advantage of reduced testing time, verification of algorithms on different systems before implementation, and cost-saving. Today’s simulation softwares are capable of providing the physics of the simulation such as torque requirements of the joints which aid in the selection of appropriate hardware. In this research, Webots, an open-source physics-based simulation, and visualization software is evaluated and then used to study and evaluate the performance of two robotic systems for a robotic assistive environment for persons with upper limb disabilities. This includes a wheelchair, a table with objects, and two robotic arms attached to …

Investigating A Finite Element Model Updating Methodology For Characterizing Mechanical Properties Of Ncf Composites, Pasworn Chanchai

Mechanical and Aerospace Engineering Theses - Archive

Composite materials have been a key breakthrough in developing aircraft structures. Their superior strength and stiffness-to-density ratio, which are unmatched by no other materials, allow engineers to create high strength and ultra-lightweight aircraft structures. Recently, non-Crimp Fabric (NCF) composites have emerged as attractive alternatives to traditional autoclave pre-impregnated composites allowing for lower production costs, better handling and improved shelf life while maintaining excellent in-plane mechanical properties compared to other types of textile composites. NCF out-of-plane mechanical properties can also be enhanced by stitching a high tensile strength yarn throughout their entire laminate thickness, improving the resistance to delamination. However, stitch-reinforced …

Characterization And Enhancement Of Mechanical Properties In Thermoplastic Fff Parts Using In-Situ Annealing, Rhugdhrivya Rane

Mechanical and Aerospace Engineering Dissertations - Archive

Fused filament fabrication is one of the most common and widely used additive manufacturing techniques. Owing to its ease of use, availability and cheap feedstock it provides a significant advantage over other AM techniques. But these advantages are overshadowed by the fact that FFF parts show high anisotropy and reduced mechanical properties as compared to conventional manufacturing techniques. Literature review of previous research works show multiple approaches to enhance the mechanical properties of FFF parts but each of these techniques have limitations to either the geometries that can be printed or involve complex expensive setups. In one such technique a …

Shape Modeling, Attitude Estimation, And Classification Of Artificial Resident Space Objects (Rso) Using Photometric Light Curves, Katiyayni Balachandran

Mechanical and Aerospace Engineering Dissertations - Archive

Light curve inversion (LCI) has proven valuable in using photometric measurements to optimize various physical parameters of a resident space object (RSO) such as rotational period about its own spin axis, pole orientation and others. Other characteristics such as shape and size are dependent on the surface brightness. To accurately determine size, shape, spin rate, or attitude information of an unresolved resident space object, photometry is required to capture the relatively rapid changes in brightness that these objects can exhibit. LCI has been developed significantly for asteroids, although not fool-proof for artificial RSOs. Satellites and space debris, unlike asteroids, are …

Theoretical And Experimental Analysis And Optimization Of Thermal Conduction In Electrochemical And Latent Heat Energy Storage Systems, Amirhossein Mostafavi

Mechanical and Aerospace Engineering Dissertations - Archive

Phase change materials (PCMs) are used commonly for energy storage purposes. Thermal energy can be stored in a PCM with a variety of configurations such as PCM slabs, cartesian and cylindrical finned systems. Heat transfer in PCM storage systems can be from a heat transfer fluid (HTF) or a heat source at constant temperature to adjacent PCM. The rate of heat transfer is limited by thermal properties. Fin insertion can improve the heat transfer inside the PCM. Chapters 2 and 3 derive and solve the governing energy equations to determine the transient temperature distribution in the PCM due to the …

Rotor Performance Model (Rpm), Chadwick Scott Balfantz

Mechanical and Aerospace Engineering Theses - Archive

Rotorcraft performance modeling is of high interest with multiple industry codes in existence, many of which are high-fidelity and are comprehensive in the analyses that are achievable. Along with the high-fidelity and the comprehensive nature of the industry codes comes an equally high level of complexity in the inputs required to extract meaningful results. The ever-increasing fidelity in the existing codes creates a need for an analysis code that is built to be highly flexible, designed from the top down and implemented from the bottom up in a structured format. The Rotor Performance Model (RPM) was developed to provide high-fidelity …

Nonlinear Model Development And Validation For Ball And Plate Control System, Zachary Richter

Master's Theses

Ball and plate balancing control systems are commonly studied due to the complex dynamics associated with the instability of the system in open-loop. For simplicity, mathematical models describing the ball and plate dynamics are often linearized and the effects of complex motion are assumed to be negligible. These assumptions are rarely backed with evidence or explanations validating the simplified form of the dynamical equations of motion. This thesis focuses on developing a nonlinear model that more accurately defines the dynamics of the system, in order to quantify the error of linear and nonlinear models when compared to a Simscape physical …

A Manufacturing-To-Response Pathway For Formed Carbon Fiber Reinforced Polymer Composite Structures, Madhura Limaye

All Theses

Over the past decade, there has been an increased adoption of thermoplastic and thermoset based continuous carbon fiber reinforced polymer (CFRP) composites for structural applications in several industries. Among the different manufacturing methods, thermoforming process for thermoplastic based continuous CFRP’s offer a major advantage in reducing cycle times for large scale productions. Similarly, out-of-autoclave curing process for thermoset based continuous CFRP’s using heated tooling enables production of large composite structures. However, these manufacturing processes can have a significant impact on the structural performance of parts by inducing undesirable effects. These effects include inhomogeneous fiber orientations, thickness variations, and residual stresses …

Rapid Annealing Of Perovskite Solar Cell Thin Film Materials Through Intense Pulse Light., Amir Hossein Ghahremani

Electronic Theses and Dissertations

Perovskite solar cells (PSCs) have garnered a great attention due to their rapid efficiency improvement using cheap and solution processable materials that can be adapted for scalable high-speed automated manufacturing. Thin film perovskite photovoltaics (PVs) are typically fabricated in an inert environment, such as nitrogen glovebox, through a set of deposition and annealing steps, each playing a significant role on the power conversion efficiency (PCE), reproducibility, and stability of devices. However, atmospheric processing of PSCs would achieve lucrative commercialization. Therefore, it is necessary to utilize materials and methods that enable successful fabrication of efficient PSCs in the ambient environment. The …

Object Classication, Detection And State Estimation Using Yolo V3 Deep Neural Network And Sensor Fusion Of Stereo Camera And Lidar, Kamalkumar Bharatkumar Mehta

Mechanical and Aerospace Engineering Theses - Archive

Real-time object classification, localization, and detection with region-based convolution neural network (R-CNN) require high computational power, or it consumes a tremendous amount of time with the use of the available onboard computer system. Therefore, either of those ways is not practical in real-time object detection. In contrast, the YOLO-v3 network, which stands for you only look once, that uses the YOLO algorithm seems to be practical in live object classification, localization, and detection, since the YOLO algorithm seems to work faster than the sliding window algorithm used by R-CNN. Sensor fusion in this context requires estimation and association of information …

Towards Real-Time Energy Efficiency Analysis Of A Hydraulic System, Montasir Mamun Mithu

Masters Theses

The study aims at developing a real-time data analysis system for the energy efficiency study of hydraulic systems. It also aims at implementing automation for hydraulic systems so that energy efficiency can be improved using the real-time approach. This research uses a system-level experimental methodology. A linear push system hydraulic prototype is developed for the study. The prototype contains hydraulic actuator, shock absorber, electronic flow control valve, and electronic sensor. This prototype is used to experiment with different operating conditions to characterize hydraulic system behavior. A real-time data analysis system is developed using LabVIEW and an Open Platform Communication (OPC) …

Design, Development, And Testing Of Research Payloads On Various Suborbital Flight-Test Platforms, Vijay Vishal Duraisamy

Doctoral Dissertations and Master's Theses

With recent advances in the commercial space industry, suborbital payload launches have become more common and accessible to researchers actively seeking solutions for problems involving prolonged space travel and future missions to Moon and Mars. Suborbital payload missions compared to orbital launches are less expensive and offer faster turnaround times; however, the novelty of this domain provides unique challenges. This multidisciplinary research effort aims to tackle some of these challenges by detailing the design, development, and testing techniques followed in the successful launch and recovery of payload experiments in currently active and upcoming suborbital launch vehicles. The research methodology involves …

Investigation Of Different Hatch Strategies On High Entropy Alloy Fabrication By Selective Laser Melting, Joni Chandra Dhar

Theses and Dissertations

This study investigated the synthesis of CuCrFeNiTiAl high entropy alloy (HEA) from pure elements using selective laser melting (SLM). The objectives are to validate the feasibility of the HEA fabrication from elemental powder materials, and to examine the effect of various hatch strategies and energy densities on the microstructures and other materials properties. 3D samples of CuCrFeNiTiAl alloy were fabricated under different energy densities and with different scan vector lengths. The as-built samples were characterized by X-ray diffraction (XRD), and the microstructures were observed using scanning electron microscopy (SEM). The XRD results showed that face centered cubic, and body centered …

Vapor-Selective Active Membrane Energy Exchanger For High Efficiency Outdoor Air Treatment, Andrew J. Fix, James E. Braun, David M. Warsinger

School of Mechanical Engineering Faculty Publications

As much as 40% of the total load on air conditioning systems can be attributed to condensation dehumidification. However, new water vapor-selective membranes present a unique opportunity to greatly reduce the power requirements for moisture removal by avoiding phase change and have thus been ranked as a top alternative to traditional HVAC systems. To date, however, all such systems have relied on the assumption of constant temperature, even terming the technology “isothermal dehumidification.” This work proposes a membrane-based air cooling and dehumidification approach, referred to as the Active Membrane Energy Exchanger (AMX), which is the first to provide simultaneous, yet …