Mechanical Engineering Commons^™

3d-Printed Microswimmers With Nanostructures For Color Tracking, Cara Koepele, Maria Guix, David Cappelleri

The Summer Undergraduate Research Fellowship (SURF) Symposium

Two-Photon Polymerization (TPP) is a fabrication technique based on the localized linking of photosensitive materials resulting from femtosecond – a quadrillionth of a second – exposure to a laser. Such materials are based on building blocks named monomers that combine under certain stimuli (i.e. light) to form chains or complex networks. Utilization of TPP as a method for micro-3D printing has expanded the field of microrobotics, which presents medical solutions for minimizing procedure invasiveness as well as increasing treatment and diagnosis accuracy. One of the challenges in achieving desired accuracies is designing trackable features onto a microrobot. With the capabilities …

Modal Phonon Transport Across Interfaces By Non-Equilibrium Molecular Dynamics Simulation, Yang Zhong, Tianli Feng, Xiulin Ruan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Phonons represent the quantization of lattice vibration, responsible for heat transfer in semiconductors and dielectrics. Phonon heat conduction across interfaces is crucially important for the thermal management of real-life devices such as smartphones, electric vehicles, and satellites. Although recent studies have broadly investigated spectral phonon contribution to lattice thermal conductivity, the mechanism of phonon modal transport across interfaces is still not well-understood. Previous models, including the acoustic mismatch model (AMM) and diffuse mismatch model (DMM), only consider elastic process while neglecting inelastic phonon contributions. Herein, we employ spectral Non-Equilibrium Molecular Dynamics Simulation (NEMD) to probe the temperature and heat flux …

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

The Summer Undergraduate Research Fellowship (SURF) Symposium

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

Stability Analysis Of A Flexible Vehicle Model Controlled By Human Pilot Models, Abhishek Ajmani, Anil Bajaj

The Summer Undergraduate Research Fellowship (SURF) Symposium

There is a constant race among automobile manufactures to design safer vehicles while minimizing weight to reduce power consumption. Additionally, organizations like NASA and SpaceX are persistently working toward creating reliable, lightweight rovers to be used on the surface of Mars. However, the lightweight requirement often increases vehicle flexibility, which further develops a tendency toward instability in the lateral (sideways) direction. This investigation develops a mathematical model that represents the dynamics of a flexible vehicle in forward motion, and a heuristic human pilot model is proposed which controls the vehicle. Following such formulation, the combined vehicle and pilot model is …

Secondary Atomization: Drop Breakup In A Continuous Air Jet, Grant S. Sondgeroth, Longchao Yao, Catriona M.L. White, Daniel R. Guildenbecher, Jun Chen, Paul E. Sojka

The Summer Undergraduate Research Fellowship (SURF) Symposium

Understanding drop breakup will optimize aircraft engine performance, reduce agro-chemical overspray, and improve pharmaceutical tablet efficacy. Large fuel fragments in engines lead to lowered fuel economy and higher pollutant emissions, while small drops yield more agro-spray drift into surrounding residential and environmental zones. Better pharmaceutical tablets will improve drug uptake and patient comfort.

Engineers and scientists are currently unable to predict the number, size, and velocity of fragments formed during important drop breakup processes. Therefore, we are required to measure these quantities. We use digital inline holography (DIH) to record three-dimensional diameter and position data for fragments formed during multi-mode …

Characterization Of Novel Photoresists For Sted-Enhanced Nanolithography, Brandon R. Franz, Paul Somers, Xianfan Xu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Stimulated emission depletion (STED) applied to nanolithography has greatly improved achievable resolutions and quality of nanoscale structures. The special resin used, called a photoresist, is currently the major limiting factor in further improvement in resolution and structure quality. Characterizing new formulations of photoresists and comparing their performance in STED-enhanced nanolithography to the performance of current formulations will allow for greater resolution and structure quality. With each photoresist, line structures are produced with a two-laser system including a writing, or excitation, laser and a depletion, or STED, laser. The line structures are exposed to the STED laser for a short duration …

Comparative Analysis Of Impact Attenuation Properties From Soccer Headgear, Kevin G. Mciver, Goutham N. Sankaran, Justin J. Markel, Tom M. Talavage, Larry J. Leverenz, Eric A. Nauman

The Summer Undergraduate Research Fellowship (SURF) Symposium

Athletes suffering from long-term neurocognitive deficiency due to subconcussive impacts is a major concern for football and soccer players today. Football players wear helmets that can help reduce injury risks like skull fractures, and these helmets must meet standard criteria that determinines how well a functional helmet should reduce accelerations of the player’s head. Currently no standard exists for testing soccer headgear despite studies demonstrating soccer players experience similar magnitudes of impacts. In this study, a modal impact hammer was used in conjunction with a Hybrid III 50th percentile test dummy head to simulate impacts experienced by soccer players to …

Burning Surface Temperature Measurements Of Propellants And Explosives Using Phosphor Thermography, Ethan A. Whitaker, Alex D. Casey, Steven F. Son

The Summer Undergraduate Research Fellowship (SURF) Symposium

Temperature measurements of propellants and explosives are necessary to create accurate models which lead to better understanding of energetic characteristics such as burning rate. Previous attempts at measuring surface temperatures of burning propellants and explosives using thermocouples have suffered from large uncertainty. Thermographic phosphor thermography employs ceramic powders called phosphors whose spectroscopic properties can be used to remotely and nearly non-intrusively measure temperature. Improved methods were developed for application of this technique to energetic materials to yield more accurate, two-dimensional temperature measurements. In this study, zinc oxide doped with gallium, a thermographic phosphor, was mixed into HMX and RDX powder, …

Two-Color Polarization Spectroscopy Measurement Of Nitric Oxide, Ziqiao Chang, Aman Satija, Robert P. Lucht

The Summer Undergraduate Research Fellowship (SURF) Symposium

Nitric Oxide (NO) is a greenhouse gas that contributes to smog and acid rain. Commercial combustion engines and turbines are significant sources of NO emission. Two-color Polarization Spectroscopy (PS) will be used to measure the collision-induced resonances of NO in gas mixtures. The effect of collision partners, such as He and Ar, on the line-shape of NO molecule will be studied. This experiment requires the use of two dye laser systems to generate 226nm beam from frequency mixing of 355nm and 622nm. This enhanced the scan range and improved the ease of operation. One dye laser will be used to …

Effect Of Moment Gradient And Load Height With Respect To Centroid On The Reliability Of Wide Flange Steel Beams Subject To Elastic Lateral Torsional Buckling, Christopher D. Eamon, Alexander W. Lamb, Kapil Patki

Civil and Environmental Engineering Faculty Research Publications

The reliability of doubly-symmetric wide flange steel beams designed to the AISC Specification for Structural Steel Buildings subjected to elastic lateral torsional buckling was evaluated when considering variation in moment gradient and load height. The analysis considers continuous loads on spans subjected to various end moments with supports that are torsionally fixed and laterally supported, without additional intermediate restraints. Dead load, occupancy live load, and beam resistance random variables were considered. Beam lateral torsional buckling resistance was evaluated from numerical solution of a fundamental differential equation that accounts for the effect of moment gradient and load height. In some cases, …

Spectroscopic Contrast Of Diarylethene Molecules On Octanethiol Monolayer, Arramel Arramel, Tibor Kudernac, Nathalie Katsonis, Bernard Lucas Feringa, Bart Jan Van Wees

Makara Journal of Technology

We present a systematic scanning tunneling microscopy (STM) study of bias-dependent imaging of disulfur diarylethene (2S-DE) molecules on octanethiol (C8) monolayer at room temperature. In a rigid confinement of the C8 matrix, we did not observe any significant variation in the appearance of the 2S-DE. On the contrary, a reversal in the apparent height of the 2S-DE was present when the molecule was situated on a gold vacancy island. We attributed this finding to the presence of a new electronic state that became accessible for a tunneling event. In addition, the C8 surface structure underwent a reversible phase transformation from …

Residual Stress Measurements On The Tig Weld Joint Of 57fe15cr25ni Austenitic Steel For Structural Material Applications By Means X-Ray Diffraction Techniques, Parikin Parikin, Agus Hadi Ismoyo, Riza Iskandar, Arbi Dimyati

Makara Journal of Technology

Measurements of residual stress on the 57Fe25Cr15Ni steel plate with no-filler TIG-welding process were carried out. This work was conducted to determine the nature of weld ability in synthesized steel. The bulks were formed in a dimension of 30x20x7 mm3 to ease data retrieval. Results show that the largest residual stress occurred in the weld metal area, amounting to 82.40 MPa with lattice stretching of 0.18%. Conversely, the values decreased to 65.92 MPa and a stretch of 0.14% in the HAZ area. This residual stress is a tensile stress that can reduce the mechanical strength of the material since it …

An Efficient Palladium-Thiourea Catalysed Heck Cross-Coupling Reaction For Molecular Electronic Interest, Wan M. Khairul, Mohd Shahrul Shahmi Md Shariff, Rafizah Rahamathullah, Adibah Izzati Daud, Mustaffa Shamsuddin, Siti Kamilah Che Soh

Makara Journal of Technology

The synthesis and utilization of C-C bonds formation are concerned about the key steps for the building of several conducting molecular electronics involving many asymmetric catalysts approached, which is an essential task that most researchers would ignore in preparing these materials to enhance the production yield of cross-coupling materials. Despite the enormous progress, there still remains a great demand for economic and practicable cross-coupling processes involving ultra-low catalyst loadings with high turnover numbers due to the employment of conventional metal catalyst. Thus, there has been an excessive interest to cultivate non-phosphine palladium catalysts for excellent achievement of activity, stability, and …

A Study On Dielectric Properties Of The Cellulose Derivative-Nh4br-Glycerol- Based The Solid Polymer Electrolyte System, Nur Muhitul Jalilah Rasali, Saifful Kamaluddin Muzakir, Ahmad Salihin Samsudin

Makara Journal of Technology

The characterization of biopolymer-based solid polymer electrolytes (SPEs) has been carried out in this present work. Cellulose derivative was chosen due to its superior physical attributes. In this work, NH4Br-doped glycerol plasticized carboxyl methylcellulose-based SPEs were successfully prepared via the solution casting method. The conductivity and dielectric properties of the prepared films were investigated using the impedance analysis which presented ~1.91×10-3 Scm-1 (with addition of 6 wt% of glycerol). In addition, the studied SPE system shows a non-Debye behaviour without a single relaxation time. The findings of the research indicate that the complexes of NH4Br and glycerol in the cellulose …

Urban Drainage Management And Flood Control Improvement Using The Duflow Case Study: Aur Sub Catchment, Palembang, South Sumatra, Indonesia, Charlotte De Fraiture, Robiyanto Hendro Susanto, F.X. Suryadi, Harrini Mutiara Hapsari Wahyu

Makara Journal of Technology

Urban flooding often times staggers the livelihood in an urban area, which most likely happens in the lowland urban area. Therefore, the existing urban drainage system should be improved in order to tackle the upcoming urban flooding events, which are more than likely to be more devastating than those in the previous years. The research location is in Palembang, Sumatra, Indonesia, where 30% of its urban part is a lowland area. The selected Aur Sub Catchment is located in Silaberanti. The main objective of this research is to improve the current drainage system in order to achieve the optimal design …

Ethanol Purification Using Activated Natural Zeolite, Chandra Wahyu Purnomo, Nelliza Putri, Indra Perdana, Hirofumi Hinode

Makara Journal of Technology

Bio ethanol is one of the potential fuels in the future. However, ethanol in water mixture has an azeotropic concentration of 95.6 wt. %, which makes it difficult to purify further. The common method of purification is by using an azeotropic distillation column, which requires an intensive energy and an addition of specific solvent. In this study, ethanol purification is done using an adsorption column packed with zeolite Raschig rings. The natural zeolite ring was modified beforehand using the NaOH solution to enhance the material’s water adsorption performance. The ethanol purity can reach more than 99% with the modified zeolite …

Physical And Mechanical Properties Of Palm Kernel Oil-Based Polyester Polyurethane/Multi-Walled Carbon Nanotube Composites, Khairul Anuar Mat Amin, Muhammad Alif Zailani, Nurul Nabilah Zulkifli, Khairiah Haji Badri

Makara Journal of Technology

In this study, polyurethane (PU) films from palm kernel oil-based polyester (PKO-p) incorporated multi-walled carbon nanotubes (MWNTs) are prepared via a evaporative casting method. Nanoparticle fluid dispersions containing 0.02%, 0.03%, and 0.05% wt. of MWNTs are added into PKO-p based resin and mixed by digital probe sonicator for 30 min followed by mixing with isocyanate to produce PU-MWNTs composite films. The mechanical properties, swelling, water vapour transmission rate (WVTR) and conductivity of the PU-MWNTs composite films are examined. Results show that the toughness (T) or flexibility, the tensile strength (TS), and Young’s modulus (YM) values of PU-MWNTs composite films increase …

Personality Trait Based Intervention For Workplace Accident Prevention, Yassierli Yassierli, Nurhayati Nurhayati, Marisa Anatasia, Shamsul Bahri

Makara Journal of Technology

Previous research has suggested that some traits may be useful as the predictors of risk behaviours behaviors. Therefore, personality traits seem to play a role in accident involvement. The purpose of this study is was to explore the relationship between the personality traits based on the Big Five Inventory (BFI) and worker accident experiences in order to elaborate personality traits based intervention for workplace accident prevention. A cross cross-sectional study was conducted among 173 workers in a cement company using a set of questionnaires consisting of respondents’ characteristics, BFI, and self-reported accident experience. The correlations were computed using Goodman Kruskal’s …

Developing Methods Of Obtaining Quality Failure Information From Complex Systems, Oladapo Olalekan Bello

Graduate Theses and Dissertations

The complexity in most engineering systems is constantly growing due to ever-increasing technological advancements. This result in a corresponding need for methods that adequately account for the reliability of such systems based on failure information from components that make up these systems.

This dissertation presents an approach to validating qualitative function failure results from model abstraction details. The impact of the level of detail available to a system designer during conceptual stages of design is considered for failure space exploration in a complex system. Specifically, the study develops an efficient approach towards detailed function and behavior modeling required for complex …

Deformation Behavior Of Al/A-Si Core-Shell Nanostructures, Robert Andrew Fleming

Graduate Theses and Dissertations

Al/a-Si core-shell nanostructures (CSNs), consisting of a hemispherical Al core surrounded by a hard shell of a-Si, have been shown to display unusual mechanical behavior in response to compression loading. Most notably, these nanostructures exhibit substantial deformation recovery, even when loaded much beyond the elastic limit. Nanoindentation measurements revealed a unique mechanical response characterized by discontinuous signatures in the load-displacement data. In conjunction with the indentation signatures, nearly complete deformation recovery is observed. This behavior is attributed to dislocation nucleation and annihilation events enabled by the 3-dimensional confinement of the Al core. As the core confinement is reduced, either through …

A Spreadsheet Algorithm For Determining The Economic Feasibility Of Micro-Chp Systems In The Arkansas Manufacturing Sector, Ford R. Lewallen

Graduate Theses and Dissertations

Combined heat and power (CHP) systems are not new to the market. However, advances in technology, specifically MicroTurbines, have presented new opportunities for installations of micro-CHP units - defined as 50 kWe to 300 kWe, specifically at small- to medium-sized industrial facilities. One pressing concern is whether or not an industrial plant has a high enough process thermal load requirement to fully utilize the energy output.

This thesis will discuss simulations that were run on several actual electric and thermal load combinations, which correspond to types of manufacturing facilities commonly found in Arkansas. Analysis of the plant usage profiles will …

Advanced Methods Of Nondestructive Inspection Of Composite Structures Based On Limited Angle X-Ray Computed Tomography, Ekaterina Bostaph

Mechanical and Aerospace Engineering Dissertations - Archive

This research aimed to study the potential for breaking through object size limitations of current X-ray computed tomography (CT) systems by implementing a limited angle scanning technique. CT stands out among other industrial nondestructive inspection (NDI) methods due to its unique ability to perform 3D volumetric inspection, unmatched micro-focus resolution, and objectivity that allows for automated result interpretation. This work attempts to advance NDI technique to enable microstructural material characterization and structural diagnostics of composite structures, where object sizes often prohibit the application of full 360o CT. Even in situations where the objects can be accommodated within existing micro-CT configuration, …

Modeling And Measurements Of Thermal Transport In Li-Ion Based Energy Conversion And Storage Devices, Krishna Shah

Mechanical and Aerospace Engineering Dissertations - Archive

Heat transfer is of significant importance in energy conversion and storage devices such as Lithium-ion batteries for its safe operation and performance. Li-ion batteries are considered to be the state of the art among the energy storage devices due to their very high energy density and high power density. However, the safety of Li-ion batteries has become a concern in light of recent incidents, where there have been catastrophic events reported due to overheating of large battery packs. It is imperative to fully understand the nature of thermal transport in Li-ion cells. However, this has not been explored in detail …

Space Access Systems Design: Synthesis Methodology Development For Conceptual Design Of Future Space Access Systems, Loveneesh Rana

Mechanical and Aerospace Engineering Dissertations - Archive

The early Conceptual Design (CD) of a Space Access System (SAS) is the most abstract, innovative, and technologically challenging phase throughout the entire aerospace product development life-cycle. While it is the most important life-cycle phase which influences around 80 percent of the overall life-cycle-cost, it is also the least understood design phase. The history of space access vehicle design provides numerous examples of projects that failed due to lack of a proper technology-hardware-mission assessment in the CD phase. The present dissertation addresses this crucial phase and develops a prototype best practice solution process to advance the current state of the …

Micro/Nanoencapsulated Phase Change Materials (Pcms) Toward High Temperature Thermal Energy Storage Applications, Hanfei Zhang

Mechanical and Aerospace Engineering Dissertations - Archive

Thermal energy is one of the most important renewable energy sources because of its abundancy. However, despite the long history of people practically trying to harvest thermal energy, the efficiency of thermal energy storage and application to daily life utilization is still a major limitation, especially for high temperature (>300oC) applications. Concentrating solar power (CSP) is one of the very few technologies that have been used commercially to produce electricity from solar thermal energy. Benefiting from the extra latent heat stored during melting/freezing, phase change materials (PCMs) with a high melting point are commonly used in these systems functioning …

Field-Directed Fabrication Of Hierarchical Structures Toward Electrochemical Applications, Anirudh Balram

Mechanical and Aerospace Engineering Dissertations - Archive

The ubiquity of hierarchical structures in nature indicates an inherent advantage to having morphological features comprised of multiple length scales. Such structures help maximize interfacial surface area, allowing for efficient chemical reactions and mass transport despite volumetric constraints. In electrochemical applications such as batteries, supercapacitors, electrolysis, fuel cells, catalysis etc. there is a similar necessity to maximize electrochemically active surface area to facilitate facile charge and mass transport. Inspired by examples in nature, this work seeks to develop scalable fabrication techniques to obtain hierarchically structured high-performance electrodes for electrochemical applications, with a focus on energy applications. Particular emphasis was laid …

Numerical Investigation Of Stability Characteristics Of A Jet In Counterflow, Siddarth Chintamani

Mechanical and Aerospace Engineering Dissertations - Archive

A jet in counterflow is a configuration in which a jet is issued into an opposing external stream of fluid. Some of the possible applications of this configuration include study of pollutant discharge into body of water, aerodynamic flame holder in after burner, reduction of drag and cooling of bluff body by ejecting a jet of coolant gas into counterflowing stream, thrust vectoring of supersonic jets, sonic boom mitigation. The instability associated with flow reversal which is observed in this configuration of the jet leads to enhanced mixing. However, a detailed understanding of the dynamics and control is needed to …

Multi-Mesh Reduced-Order Basis Method For Finite Element Analysis, Ashkan Akbariyeh

Mechanical and Aerospace Engineering Dissertations - Archive

Reduced order modeling of differential equations parametrized over a parameter space can be used to accelerate optimization and parameter estimation problems. The method of snapshots or reduced order basis is well established among researchers as a tool to build reduced order models of ordinary differential equations. The reduced order basis method has been utilized for numerical solution of parametric PDE problems by researchers in recent years and has many advantages over response surface methods. The application of ROB to finite element analysis has been restricted to using a fixed mesh for snapshots. In this work, a new method is developed …

Thermal Measurement And Optimization Of Materials And Processes In A Li-Ion Cell, Vivek Vishwakarma

Mechanical and Aerospace Engineering Dissertations - Archive

Applications of Lithium-ion cells range from consumer electronics to electric cars because of their excellent electrochemical performance and energy density. However, a Li-ion cell also suffers from poor thermal transport characteristics, which reduces performance, causes overheating and thermal runaway. This work contributes towards thermal characterization of key Li-ion battery materials and identifies and improves the rate-limiting, material-level thermal conduction process in a Li-ion cell. Among the various materials within a Li-ion cell, the separator is expected to have the lowest thermal conductivity. In this work, we have carried out first-ever measurements of thermal conductivity and heat capacity of the separator …

Flexible-Continuum Robot For Bladder Tissue Diagnostics, Samson Abimbola Adejokun

Mechanical and Aerospace Engineering Theses - Archive

The aim of this thesis is to investigate and develop a robotic system capable of a transurethral palpation of any targeted area on the bladder interior wall tissue to determine the biomechanical properties of the tissue considering the urinary tract geometric constraints and to demonstrate the motion kinematics of such robot to achieve a desired robot pose normal to any localized region throughout the bladder workspace. Current technologies have, to varied degree of success, provide approximate, global diagnostics information to bladder tissue elasticity. However, no direct access qualitative methods to measure the bladder tissue properties are known. For this reason, …