Engineering Commons^™

Finding Balance In Generative Product Design, Alex Lobos

Presentations and other scholarship

Generative design develops complex forms and structures similar to those found in nature, taking advantage of automated tasks and high-scale computing power. This approach benefits designers in the creation systems that are efficient, resilient and visually engaging. These systems follow specific rules for form generation and meet clear design goals in terms of shape, strength, mass, and other physical attributes.

There is a large number of methods for creating generative systems, based on establishing desired outcomes and behaviors for how components relate to each other. Examples of methods include L-Systems, Shape Grammars, Swarm Intelligence, Form Optimization, Lattice Design, and many …

Underwater Image De-Scattering And Enhancing Using Dehazenet And Hwd, Pan-Wang Pan, Fei Yuan, En Cheng

Journal of Marine Science and Technology–Taiwan

De-scattering and edge enhancing are critical procedures for underwater images which suffer from serious contrast attenuation, color deviation, and edge blurring. In this paper, a novel method is proposed to enhance underwater images. Firstly, a Convolutional Neural Network (CNN) is trained end-to-end to estimate the transmission map. Simultaneously, the adaptive bilateral filter is used to refine the transmission map. Secondly, a strategy based on the white balance is proposed to remove the color deviation. Laplace pyramid fusion is utilized to obtain the fusion result of the haze-free and color-corrected image. Finally, the output image is transformed into the Hybrid Wavelets …

Co2-Eor Mechanisms In Huff-N-Puff Operations In Shale Oil Reservoirs Based On History Matching Results, Dheiaa Alfarge, Mingzhen Wei, Baojun Bai

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Improved Oil Recovery (IOR) techniques in Unconventional Liquids Rich Reservoirs (ULR) are still a new concept because there is no commercial project for any IOR technique so far. Carbon dioxide (CO₂) based EOR technique has been effectively applied to improve oil recovery in the tight formations of conventional reservoirs. Extending this approach to unconventional formations has been extensively investigated over the last decade because CO₂ has unique properties which make it the first option of EOR methods to be tried. However, the applications and mechanisms for CO2-EOR in unconventional reservoirs would not necessarily be the same as …

General Rules For Pre-Process Planning In Powder Bed Fusion System -- A Review, Tan Pan, Sreekar Karnati, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Powder bed fusion (PBF) is one of the current additive manufacturing techniques that can fabricate almost fully dense functional metal components. Through a layer by layer fabrication methodology, complex geometries to meet the requirements of aerospace, automotive, biomedicine industries, etc. can be produced. The success of a build largely depends on having a flawless pre-process planning, including build orientation selection, support structure optimization, process parameter chosen, etc., which closely relates to the quality of the final products. Geometric inaccuracy and poor surface quality can occur due to a bad build plan. This review presents the crucial general planning rules for …

Additive Manufacturing Of Metal Functionally Graded Materials: A Review, Yitao Chen, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Functionally graded materials (FGMs) have attracted a lot of research interest due to their gradual variation in material properties that result from the non-homogeneous composition or structure. Metal FGMs have been widely researched in recent years, and additive manufacturing has become one of the most important approaches to fabricate metal FGMs. The aim of this paper is to review the research progress in metal FGMs by additive manufacturing. It will first introduce the unique properties and the advantages of FGMs. Then, typical recent findings in research and development of two major types of metal additive manufacturing methods, namely laser metal …

Incorporation Of Automated Ball Indentation Methodology For Studying Powder Bed Fabricated 304l Stainless Steel, Sreekar Karnati, Jack L. Hoerchler, Aaron Flood, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Automated Ball Indentation (ABI) is a viable method for estimating the ductility, yield stress, and ultimate stress, among other metrics, in different metallic materials. Currently, ABI data analysis utilizes Holloman’s Power Law to model the plastic region of the true stress-true strain curve. While this formulation is accurate for some materials, its relevance for additively manufactured austenitic stainless steels, such as 304L, needed investigation. The deviation of the material’s plastic behavior from the Power Law was investigated. In order to better model this behavior, both the Voce and Ludwigson formulation were investigated. These formulations were tested for both wrought and …

Experimental Characterization Of A Direct Metal Deposited Cobalt-Based Alloy On Tool Steel For Component Repair, Xinchang Zhang, Tan Pan, Wei Li, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Die casting dies made of tool steel is subject to impact, abrasion and cyclic thermomechanical loading that delivers damage such as wear, corrosion, and cracking. To repair such defects, materials enveloping the damage need to be machined and refilled. In this study, V-shape defects with varied sidewall inclination angles were prepared on H13 tool steel substrates and refilled with cobalt-based alloy using direct metal deposition (DMD) for superior hardness and wear resistance. The microstructure of rebuild samples was characterized using an optical microscope (OM) and scanning electron microscope (SEM). Elemental distribution from the substrate to deposits was analyzed using energy …

Effects Of Thermal Camera Resolution On Feature Extraction In Selective Laser Melting, Xin Wang, Cody S. Lough, Douglas A. Bristow, Edward C. Kinzel, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective Laser Melting (SLM) is a common additive manufacturing process which uses a laser energy source to fuse metal powder layer by layer. Engineering properties and microstructure are related to the part’s thermal history. It is important to measure the thermal history in-situ to qualify parts and provide the sensing which is necessary for process control. A common measurement tool for this purpose is a thermal camera that records the thermal emission of the part’s surface.

This study investigates the effects of spatial sampling resolution of thermal cameras when monitoring the temperature in SLM processes. High-fidelity simulation of an SLM …

Development Of Pre-Repair Machining Strategies For Laser-Aided Metallic Component Remanufacturing, Xinchang Zhang, Wenyuan Cui, Leon Hill, Wei Li, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Remanufacturing worn metallic components can prolong the service life of parts that need frequent replacement but are extremely costly to manufacture, such as aircraft titanium components, casting dies. Additive manufacturing (AM) technology enables the repair of such valuable components by depositing filler materials at the worn area layer by layer to regenerate the missing geometry. In general, damaged parts would be inspected and pre-machined prior to material deposition to remove oil, residue, oxidized layers or defects located in inaccessible regions. Therefore, the motivation of this paper is to introduce pre-repair machining strategies for removing contaminated materials from damaged components and …

Recyclability Of 304l Stainless Steel In The Selective Laser Melting Process, Austin T. Sutton, Caitlin S. Kriewall, Ming-Chuan Leu, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During part fabrication by selective laser melting (SLM), a powder-bed fusion process in Additive Manufacturing (AM), a large amount of energy is input from the laser into the melt pool, causing generation of spatter and condensate, both of which have the potential to settle in the surrounding powder-bed compromising its reusability. In this study, 304L stainless steel powder is subjected to five reuses in the SLM process to assess its recyclability through characterization of both powder and mechanical properties. Powder was characterized morphologically by particle size distribution measurements, oxygen content with inert gas fusion analysis, and phase identification by X-ray …

Developing Multi-Scale Models For Water Quality Management In Drinking Water Distribution Systems, Ahmed A. Abokifa

McKelvey School of Engineering Graduate Student Theses & Dissertations

Drinking water supply systems belong to the group of critical infrastructure systems that support the socioeconomic development of our modern societies. In addition, drinking water infrastructure plays a key role in the protection of public health by providing a common access to clean and safe water for all our municipal, industrial, and firefighting purposes. Yet, in the United States, much of our national water infrastructure is now approaching the end of its useful life while investments in its replacement and rehabilitation have been consistently inadequate. Furthermore, the aging water infrastructure has often been operated empirically, and the embracement of modern …

Radiological Pathological Correlations In Chronic Traumatic Encephalopathy, Mihika Gangolli

McKelvey School of Engineering Graduate Student Theses & Dissertations

Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease that has been increasingly linked to traumatic brain injury. The neuropathology that distinguishes CTE from other tauopathies includes hyperphosphorylated tau (pTau) tangles and tau positive astrocytes irregularly distributed in cortical sulcal depths and clustered around perivascular foci. These features are clearly identified using immunohistochemistry, but are undetectable to current clinical imaging methods. Diffusion imaging has been proposed as a noninvasive method to detect the pathognomonic lesion of CTE in vivo because of its high sensitivity to microstructural alterations in tissue structure. While several diffusion imaging approaches, ranging from diffusion tensor imaging …

In Vivo Vascular Imaging With Photoacoustic Microscopy, Hsun-Chia Hsu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Photoacoustic (PA) tomography (PAT) has received extensive attention in the last decade for its capability to provide label-free structural and functional imaging in biological tissue with highly scalable spatial resolution and penetration depth. Compared to modern optical modalities, PAT offers speckle-free images and is more sensitive to optical absorption contrast (with 100% relative sensitivity). By implementing different regimes of optical wavelength, PAT can be used to image diverse light-absorbing biomolecules. For example, hemoglobin is of particular interest in the visible wavelength regime owing to its dominant absorption, and lipids and water are more commonly studied in the near-infrared regime.

In …

Engineering Robust And Programmable Biological Systems, Tatenda Shopera

McKelvey School of Engineering Graduate Student Theses & Dissertations

The ability to engineer programmable biological systems using complex artificial gene networks has great potential to unlock important innovative solutions to many biotechnological challenges. While cells have been engineered to implement complex information processing algorithms and to produce food, materials, and pharmaceuticals, many innovative applications are yet to be realized due to our poor understanding of how robust, reliable, and predictable artificial gene circuits are built. In this work, we demonstrate that robust complex cellular behaviors (e.g., bistability and gene expression dynamics) can be achieved by engineering gene regulatory architecture and increasing the complexity of genetic networks. We further demonstrate …

Brain-Computer Interfaces Using Electrocorticography And Surface Stimulation, Jesse Wheeler

McKelvey School of Engineering Graduate Student Theses & Dissertations

The brain connects to, modulates, and receives information from every organ in the body. As such, brain-computer interfaces (BCIs) have vast potential for diagnostics, medical therapies, and even augmentation or enhancement of normal functions. BCIs provide a means to explore the furthest corners of what it means to think, to feel, and to act—to experience the world and to be who you are. This work focuses on the development of a chronic bi-directional BCI for sensorimotor restoration through the use of separable frequency bands for recording motor intent and providing sensory feedback via electrocortical stimulation. Epidural cortical surface electrodes are …

Hemodynamic Effects On Embryonic Arterial Growth And Matrix Remodeling, Maria Gabriela Espinosa

McKelvey School of Engineering Graduate Student Theses & Dissertations

Hemodynamic forces drive cardiovascular morphogenesis and remodeling in the developing embryo. Changes to the embryonic hemodynamic environment have been shown to induce a variety of congenital heart defects, but little attention has been given to vasculature-specific defects. Although vascular development has been widely studied in the context of genetics and molecular biology, this work investigates the impact of hemodynamic forces on arterial development and mechanics.

The dorsal aorta (DA) is the first intraembryonic vessel to form. Its passive mechanical properties are determined by the deposition of extracellular matrix (ECM) proteins, a hallmark of arterial maturation. We hypothesized that hemodynamic changes …

Bio-Inspired Multi-Spectral Image Sensor And Augmented Reality Display For Near-Infrared Fluorescence Image-Guided Surgery, Nan Cui

McKelvey School of Engineering Graduate Student Theses & Dissertations

Background: Cancer remains a major public health problem worldwide and poses a huge economic burden. Near-infrared (NIR) fluorescence image-guided surgery (IGS) utilizes molecular markers and imaging instruments to identify and locate tumors during surgical resection. Unfortunately, current state-of-the-art NIR fluorescence imaging systems are bulky, costly, and lack both fluorescence sensitivity under surgical illumination and co-registration accuracy between multimodal images. Additionally, the monitor-based display units are disruptive to the surgical workflow and are suboptimal at indicating the 3-dimensional position of labeled tumors. These major obstacles have prevented the wide acceptance of NIR fluorescence imaging as the standard of care for cancer …

Multi-Gpu Acceleration Of Iterative X-Ray Ct Image Reconstruction, Ayan Mitra

McKelvey School of Engineering Graduate Student Theses & Dissertations

X-ray computed tomography is a widely used medical imaging modality for screening and diagnosing diseases and for image-guided radiation therapy treatment planning. Statistical iterative reconstruction (SIR) algorithms have the potential to significantly reduce image artifacts by minimizing a cost function that models the physics and statistics of the data acquisition process in X-ray CT. SIR algorithms have superior performance compared to traditional analytical reconstructions for a wide range of applications including nonstandard geometries arising from irregular sampling, limited angular range, missing data, and low-dose CT. The main hurdle for the widespread adoption of SIR algorithms in multislice X-ray CT reconstruction …

Forward Electrophysiological Modeling And Inverse Problem For Uterine Contractions During Pregnancy, Mengxue Zhang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Uterine contractile dysfunction during pregnancy is a significant healthcare challenge that imposes heavy medical and financial burdens on both human beings and society. In the U.S., about 12% of babies are born prematurely each year, which is a leading cause of neonatal mortality and increases the possibility of having subsequent health problems. Post-term birth, in which a baby is born after 42 weeks of gestation, can cause risks for both the newborn and the mother. Currently, there is a limited understanding of how the uterus transitions from quiescence to excitation, which hampers our ability to detect labor and treat major …

Additive Manufacturing Of Metal Bandpass Filters For Future Radar Receivers, Bradley Grothaus, Dane Huck, Austin T. Sutton, Ming-Chuan Leu, Ben Brown

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective laser melting (SLM) is a powder-bed fusion (PBF) process that bonds successive layers of powder with a laser to create components directly from computer-aided design (CAD) files. The additive nature of the SLM process in addition to the use of fine powders facilitates the construction of complex geometries, which has captured the attention of those involved in the design of bandpass filters for radar applications. However, a significant drawback of SLM is its difficulty in fabricating parts with overhangs necessitating the use of support structures, which, if not removed, can greatly impact the performance of bandpass filters. Therefore, in …

Mechanical Properties Of Zr-Based Bulk Metallic Glass Parts Fabricated By Laser-Foil-Printing Additive Manufacturing, Yingqi Li, Ming-Chuan Leu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The application of bulk metallic glasses (BMGs) has been traditionally limited to parts with small dimensions and simple geometries, due to the requirement of fast cooling during the conventional process of casting. This research exemplifies a promising additive manufacturing method, i.e., laser-foil-printing (LFP), to fabricate high-quality BMG parts with large dimensions and complex geometries. In this study, Zr_52.5Ti₅Al₁₀Ni_14.6Cu_17.9 BMG parts were fabricated by LFP technology in which MG foils are laser welded layer-by- layer upon a substrate. The mechanical properties of the fabricated BMG parts were measured using micro-indentation, tensile test …

Effects Of Identical Parts On A Common Build Plate On The Modal Analysis Of Slm Created Metal, Tristan Cullom, Troy Hartwig, Ben Brown, Kevin Johnson, Jason Blough, Andrew Barnard, Robert G. Landers, Douglas A. Bristow, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The frequency response of parts created with Additive Manufacturing (AM) is a function of not only process parameters, powder quality, but also the geometry of the part. Modal analysis has the potential to evaluate parts by measuring the frequency response which are a function of the material response as well as the geometry. A Frequency Response Function (FRF) serves as a fingerprint of the part which can be validated against the FRF of a destructively tested part. A practical scenario encountered in Selective Laser Melting (SLM) involves multiple parts on a common build plate. Coupling between parts influences the FRF …

Effect Of Environmental Variables On Ti-64 Am Simulation Results, Aaron Flood, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In metal AM the environment is critical and therefore care should be taken to ensure that the simulation matches reality. This paper will investigate the effect that various environmental factors have on the results of the simulation. This will help to determine their importance in the simulation setup. The material properties which relate to this are the convective coefficient and the emissivity. These material properties will be investigated to determine their effect on the outcome of the simulation. In addition to these properties, the size of the substrate will be investigated to determine if any results are altered. Lastly, the …

Characterization Of Impact Toughness Of 304l Stainless Steel Fabricated Through Laser Powder Bed Fusion Process, Sreekar Karnati, Atoosa Khiabhani, Aaron Flood, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this research, the impact toughness of powder bed based additively manufactured 304L stainless steel was investigated. Charpy specimens were built in vertical, horizontal and inclined (45⁰) orientations to investigate the variation in toughness with build direction. These specimens were tested in as-built and machined conditions. A significant difference in toughness was observed with varying build directions. The lowest toughness values were recorded when the notch was oriented in line with the interlayer boundary. The highest toughness was recorded when the notch was perpendicular to the interlayer boundary. A significant scatter in toughness values was also observed. The variation and …

Digital Acoustic Modem Design For Narrowband Underwater Vehicle Communications, Ertan Uysal, Serhat Yılma, Murat Kuzlu

Journal of Marine Science and Technology–Taiwan

Underwater communication has become a crucial data transmission technology for commercial and military marine applications in the last few decades. However, most underwater communication applications still use analogue technologies. Recent advances in digital signal processing technology have enabled numerous applications in different fields, especially in underwater wireless communications. This paper presents a digital underwater communication system, which transmits and receives acoustic signals via hydrophones employed as acoustic transmitters and receiver units. In this study, coding and modulation methods were also implemented in the prototype through a series of simulations.

Micro Combustion Of Primary Reference Fuels In Narrow Heated Channels, Veerendra Naralasetti

LSU Master's Theses

Conventional fuel testing machines like CFR engines require large quantities of fuel. The current study seeks to overcome this limitation by introducing an alternative method using a microscale combustion reactor which consumes relatively small amounts of fuel (100-250 ml). For this reason, Primary Reference Fuels (PRF’s: volumetric mixtures of n-heptane and iso-octane) which are simple surrogates of gasoline are selected to test using micro reactor. The primary goal is to determine the effectiveness of using the micro reactor setup to differentiate fuels of different octane number. Experiments with stoichiometric PRF/air mixtures are performed inside a cylindrical quartz tube of 1mm …

Robust Engineering Of Dynamic Structures In Complex Networks, Walter Botongo Bomela

McKelvey School of Engineering Graduate Student Theses & Dissertations

Populations of nearly identical dynamical systems are ubiquitous in natural and engineered systems, in which each unit plays a crucial role in determining the functioning of the ensemble. Robust and optimal control of such large collections of dynamical units remains a grand challenge, especially, when these units interact and form a complex network. Motivated by compelling practical problems in power systems, neural engineering and quantum control, where individual units often have to work in tandem to achieve a desired dynamic behavior, e.g., maintaining synchronization of generators in a power grid or conveying information in a neuronal network; in this dissertation, …

Controlling The Oxygen Microenvironment: The Role Of Hif-1Α In Early Tumor Progression, Sandra Lam

McKelvey School of Engineering Graduate Student Theses & Dissertations

Cancer drug efficacy has remained a critical obstacle for researchers as it has one of the lowest probabilities of success compared to other diseases. One method to help improve this success rate is to create better tumor models on which to perform the drug testing. With growing interesting in microphysiological systems, scientists can create more advanced in vitro models of human organ systems as well as diseased states. These “organ-on-a-chip” platforms aim to improve drug response prediction for both efficacy and toxicity. One underappreciated characteristic of many disease states is that they are often at a lower oxygen tension that …

Aromatic Tolerance And Utilization Mechanisms Of Rhodococcus Opacus Pd630 To Produce Value-Added Products From Lignin, Wiliam Henson

McKelvey School of Engineering Graduate Student Theses & Dissertations

Lignocellulosic biomass is a potential renewable feedstock for the microbial production of fuels and chemicals. For microbial utilization, lignocellulosic biomass must undergo pretreatment (e.g., thermochemical and enzymatic processing) to release fermentable sugars.

Lignin comprises ~15-30% of lignocellulosic biomass, and lignin-derived aromatic compounds released during pretreatment can inhibit the microbial conversion of lignocellulosic sugars to bioproducts. Additionally, cost-effective separation of lignin and lignin by-products from lignocellulosic sugars remains a challenge, and current processes generate large waste streams that are typically burned or discarded. Thus, efforts are underway to improve microbial tolerance to lignin by-products and to develop approaches for valorizing waste …

Additive Manufacturing Of Liners For Shaped Charges, Jason Ho, Cody Lough, Phillip R. Mulligan, Edward C. Kinzel, Catherine E. Johnson

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A Shaped Charge (SC) is an explosive device used to focus a detonation in a desired direction, and has applications in oil extraction, weaponry and demolition. The focusing relies on a void in the explosive mass, shaped by a metal liner that becomes a super-heated projectile during detonation. Additive Manufacturing (AM) allows greater design freedom and geometric complexity for the liner portion of the SC. Specifically, hierarchical structuring and functional grading can potentially provide greater velocity, directionality, and efficiency. In this work, Selective Laser Melting (SLM) is used to explore different geometries for an SC liner made out of SS …