Engineering Commons^™

Generating High Purity Embryonic Stem Cell-Derived Cell Populations For Transplantation Following Spinal Cord Injury, Dylan A. Mccreedy

McKelvey School of Engineering Graduate Student Theses & Dissertations

Embryonic stem cells hold great potential for cell replacement strategies in the central nervous system. Pre-differentiation into various neural cell types can help generate tissue-specific cell populations that can replace cells and tissue lost due to do injury or disease. A small number of undifferentiated pluripotent stem cells persist in most transplant populations even after pre-differentiation. Given the right environment, i.e. biomaterial scaffolds, these cells can lead to tumor formation thereby eliminating any potential therapeutic benefit. This dissertation focused on the development of high purity embryonic stem cell-derived cell populations devoid of pluripotent stem cells for transplantation into the central …

Engineering Poly(Ethylene Glycol) Materials To Promote Cardiogenesis, Amanda Walker Smith

McKelvey School of Engineering Graduate Student Theses & Dissertations

Heart failure is one of the leading causes of death worldwide, and the current costs of treatment put a significant economic burden on our societies. After an infarction, fibrotic tissue begins to form as part of the heart failure cascade. Current options to slow this process include a wide range of pharmaceutical agents, and ultimately the patient may require a heart transplant. Innovative treatment approaches are needed to bring down costs and improve quality of life. The possibility of regenerating or replacing damaged tissue with healthy cardiomyocytes is generating considerable excitement, but there are still many obstacles to overcome. First, …

On The Futility Of Thermal Through-Silicon-Vias, Chung Han Chou, Nien Yu Tsai, Hao Yu, Yiyu Shi, Jui Hung Chien

Electrical and Computer Engineering Faculty Research & Creative Works

Thermal integrity is one of the most important challenges faced by three-dimensional integrated circuits (3D ICs). Towards this, thermal through-silicon-vias (TTSVs) have been widely used to assist heat dissipation. The metal inside TTSVs can conduct heat more effectively than the silicon substrate, and the metal bumps underneath TTSVs can help heat penetrate through the inter-layer thermal interface material (TIM). However, the surrounding silicon dioxide blocks the heat flowing into them. This makes the effectiveness of TTSVs questionable. In this paper, we argue that some existing TTSV models fail to capture those effects. Experimental results based on finite element simulations verify …

Improving Radiotherapy Targeting For Cancer Treatment Through Space And Time, Camille Noel

McKelvey School of Engineering Graduate Student Theses & Dissertations

Radiotherapy is a common medical treatment in which lethal doses of ionizing radiation are preferentially delivered to cancerous tumors. In external beam radiotherapy, radiation is delivered by a remote source which sits several feet from the patient's surface. Although great effort is taken in properly aligning the target to the path of the radiation beam, positional uncertainties and other errors can compromise targeting accuracy. Such errors can lead to a failure in treating the target, and inflict significant toxicity to healthy tissues which are inadvertently exposed high radiation doses.

Tracking the movement of targeted anatomy between and during treatment fractions …

Determination Of Mortar Saturation Methods Based On Mri Scanning Image, Hsiang-Wei Chiang, Ran Huang

Journal of Marine Science and Technology–Taiwan

Magnetic resonance imaging (MRI) is widely used in the medical field and among one of the greatest inventions in recent years. In MRI images, the bright zone denotes signals that are generated by water in the specimen. However, solid cement-based materials lack water. Therefore, developing a method to achieve optimal saturation for cement-based materials is crucial for MRI scanning. In this study, the immersion, boiling, and vacuum methods were used to achieve saturation for various mortar specimens with w/c ratios of 0.45, 0.55, and 0.65. By comparing MRI images and absorption test results, we found that the vacuum method tends …

Identification Of Pipelines From The Secondary Reflect Wave Travel Time Of Ground-Penetrating Radar Waves, Kun-Fa Lee, Tan-K Wang1, Yu-Ming Kang, Cheng-Sung Wang, Kuo-An Lin

Journal of Marine Science and Technology–Taiwan

When using ground-penetrating radar to identify underground pipelines of similar dielectric constants (i.e. PE and PVC), misidentification is quite common. In this study, we apply reflected travel time of radar waves into the PE- and PVC- dielectric constants and the differentiation becomes possible. We have conducted the experiments using the nonmetal PE- and PVC- pipelines as well as the heavy metal (iron) pipelines in a water environment. Based on a travel- time calculation, the dielectric constants of non-metal pipelines with similar composition (PE ＝ 2.3 and PVC ＝ 3.0) were quite close. The error between the experimental and theoretical values …

Bayesian-Network-Based Hydro-Power Fault Diagnosis System Development By Fault Tree Transformation, Chaur-Gong Jong, Sou-Sen Leu

Journal of Marine Science and Technology–Taiwan

Currently, fault diagnosis of reservoir facilities relies mostly on check-list evaluation. The results and qualities of evaluation are limited by experience and ability of the evaluators, which may not achieve the goal of systematic assessment in a consistent manner. To overcome the limitation of the traditional approach, this research develops a fault diagnosis and evaluation system for reservoir facility by utilizing multi-state Fault-Tree Analysis (FTA) technique, in conjunction with Bayesian Networks (BN) which incorporate expert experiences through lateral linkages among BN nodes and weighting factors. The system has been used to analyze and verify against three hydro-power systems currently in …

A Lean Prebid Planning Model For Construction Contractors: A Case Study In Vietnam, Hui Ping Tserng, Samuel Yen-Liang Yin, Thanh Long Ngo

Journal of Marine Science and Technology–Taiwan

Prebid planning is an essential function of construction project management that allows contractors to obtain projects with low cost while achieving other criteria. It also helps contractors during project execution and management. This research applied the manufacturing industry’s lean theory to propose a lean prebid planning model (LPPM) for construction contractors. The LPPM can significantly eliminate the main types of waste in construction projects because it effectively combines three important concepts in the manufactureing industry: transformation, workflow, and value generation. This model includes seven arrangement steps, which are described systematically to help contractors with real-world applications. A case study was …

Experimental Study On The Motions Of A Mooring Ship In Mixed Waves, Xian-Ying Shi, Yang Yang, Ning-Chuan Zhang, Yu-Xin Huang

Journal of Marine Science and Technology–Taiwan

By employing the method of bimodal spectral simulations, a series of experiments were performed on a 266,000 m3 LNG ship moored to an island berth in mixed waves. In the physical model experiments, a special effort was made to investigate how changing wave conditions affect the motion responses of the mooring ship in mixed waves. Therefore, this paper mainly engages in the analysis of such effects resulted from wave condition changes of mixed waves from such perspectives as the distribution of high- and low-frequency energy, the periodic changes of low-frequency swells, the wave-height changes of low-frequency swells, and the wave-height …

Comparison Of Different Wind Stress Effects On Sst And Sss In The East China Sea Region, Hung-Jen Lee, Shih-Jen Huang, Shenn-Yu Chao, Kon-Kee Liu

Journal of Marine Science and Technology–Taiwan

Ocean circulations closely associated with the changes of wind system are investigated using a three-dimensional tidecirculated coupling model. Based on the coupling model, we apply different wind datasets, to some extent reflecting wind system variations associated with global climate change, but constant monthly temperature and salinity fields to assess the effect of differing wind strength stresses in the East China Sea region, leading to significant influences on hydrographic fields. In the model based on the Hellman-Rosenstein wind dataset, more distant from the mouth of the Changjiang River (Yangtze River), the Yellow Sea Warm Current strengthens because of the wind stress; …

A Real Case Study On The State Of Corrosion Of The Spanish Boats, José A Orosa, Juan José Galán, Mar Toledano

Journal of Marine Science and Technology–Taiwan

In this real case study we analyze various corrosion problems encountered in Spanish fleets and present possible solutions. As a first step, we developed a statistical analysis of the north Mediterranean Sea fleets to define the age of the vessels, hull construction material and main activities involved. As a result, different corrosion problems were identified as well as solutions like paint, sacrificial anodes and impressed currents, and of course, improved design. Generally, we can state that, according to the results obtained, a series of incidents have increased the repair and maintenance costs of the vessels in the area under study

Shape Optimization Of One-Chamber Perforated Mufflers Filled With Wool Using Simulated Annealing, Min-Chie Chiu

Journal of Marine Science and Technology–Taiwan

Research on dissipative and reactive mufflers has been addressed. However, the acoustical performance ―sound transmission loss (STL)― of mufflers within a constrained space is often insufficient. In this paper, to improve the acoustical efficiency, a one-chamber perforated muffler filled with sound absorbing wool optimized by using simulated annealing (SA) in conjunction with the numerical decoupling technique is presented. A numerical case in eliminating a broadband noise is also introduced. To verify the reliability of SA optimization, optimal noise abatements for the pure tone are exemplified. Before the SA operation can be carried out, the accuracy of the mathematical models has …

Practical Linear Precoder Design For Finite Alphabet Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing With Experiment Validation, Yahong Rosa Zheng, Mingxi Wang, Weiliang Zeng, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

A low complexity precoding method is proposed for practical multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems. Based on the two-step optimal precoder design algorithm that maximizes the lower bound of the mutual information with finite-alphabet inputs, the proposed method simplifies the precoder design by fixing the right singular vectors of the precoder matrix, eliminating the iterative optimization between the two steps, and discretizing the search space of the power allocation vector. For a 4 x 4 channel, the computational complexity of the proposed precoder design is reduced to 3 and 6% of that required by the original two-step algorithm …

Polarization Imaging Sensors In Advanced Feature Cmos Technologies, Raphael Njoroge Njuguna

McKelvey School of Engineering Graduate Student Theses & Dissertations

The scaling of CMOS technology, as predicted by Moore's law, has allowed for realization of high resolution imaging sensors and for the emergence of multi-mega-pixel imagers. Designing imaging sensors in advanced feature technologies poses many challenges especially since transistor models do not accurately portray their performance in these technologies. Furthermore, transistors fabricated in advanced feature technologies operate in a non-conventional mode known as velocity saturation. Traditionally, analog designers have been discouraged from designing circuits in this mode of operation due to the low gain properties in single transistor amplifiers. Nevertheless, velocity saturation will become even more prominent mode of operation …

Model Reference Robust Control For Marine Propulsion Systems With Model Uncertainty Caused By Hull Deformation, Zhixiong Li, Xinping Yan, Li Qin, Chengqing Yuan, Zhongxiao Peng

Journal of Marine Science and Technology–Taiwan

A marine propulsion system can be strongly coupled with the hull deformation in a large-scale ship. The interaction of this coupling dynamics increases the nonlinearity and complexity of the control model. Traditional control method based on the empirical PID (proportion-integration-differentiation) parameters has difficulty in dealing with the model uncertainty caused by the hull deflection. However, up to date, limited work has been done to address the model uncertainty problem of the marine propulsion system. It is therefore imperative to develop feasible and effective control systems that take the model uncertainty into account. In this study, a new method based on …

The Application Of The Genetic Adaptive Neural Network In Landslide Disaster Assessment, Jing-Wen Chen, Yung-Sheng Chue, Yie-Ruey Chen

Journal of Marine Science and Technology–Taiwan

This study applied the Genetic Adaptive Neural Network (GANN) structure to satellite image classification and the assessment of landslide disaster. First, the study conducted quantitative analysis of the various factors of slope development and natural environmental hazards in some parts of the catchment areas of the Laonong River in Southern Taiwan. Meanwhile, using the weighting ratios of various disaster causing factors inferred from the best structure of GANN, this study explored the degree of slope land disturbance. Then, this study incorporated the relationship between rainfall and landslides to draw a landslide potential map using the discriminant analysis approach combined with …

Model Simulation Of Asian Dust And Iron Depositions Over The East Asian Marginal Seas, Fujung Tsai

Journal of Marine Science and Technology–Taiwan

This study applies a dust model to investigate Asian dust and iron depositions on the East Asian marginal sea during the months of the northeasterly monsoon from November to May, when dust events are often observed. Simulated dry and wet depositions of dust are compared with measurements obtained from Taipei, Taiwan. According to the model simulation, higher concentrations of atmospheric dust occur from March to May over East Asia, resulting in greater dry and wet deposition fluxes of dust and iron within these months than other months. The monthly averaged dry and wet deposition fluxes of iron are 0.6 and …

Prediction Of Bridge Pier Scour Using Genetic Programming, Chuan-Yi Wang, Han-Peng Shih, Jian-Hao Hong, Rajkumar V Raikar

Journal of Marine Science and Technology–Taiwan

This paper presents the use of genetic programming (GP) as a tool to predict pier scour depths based on clear-water conditions of laboratory measurements by past researchers. Four main dimensionless parameterspier width, approaching flow depth, threshold flow velocity, and channel open-ratio are considered for predicting the scour depth. The performance of the GP equation is verified by comparing the results with those obtained by empirical equations. It is found that the scour depth at bridge piers can be efficiently predicted using the GP model. The advantage of the GP model is confirmed by comparing the GP results of scour depths …

Electronic And Optical Properties Of Scn And (Sc,Mn)N Thin Films Deposited By Reactive Dc-Magnetron Sputtering, Bivas Saha, Gururaj V. Naik, Vladimir P. Drachev, Alexandra Boltasseva, Ernesto Marinero, Timothy D. Sands

Birck and NCN Publications

Scandium nitride (ScN) is a rocksalt semiconductor that has attracted significant attention from various researchers for a diverse range of applications. Motivated by the prospect of using its interesting electronic structure for optoelectronic and dilute magnetic semiconductor applications, we present detailed studies of the electronic transport and optical properties of ScN and its alloys with manganese nitride (MnN). Our results suggest (a) dilute manganese doping in ScN compensates for the high n-type carrier concentrations arising due to oxygen impurities and (b) an n-type to p-type carrier type transition occurs at a composition between 5.8% and 11% Mn on Sc sites. …

Vision-Based Process Monitoring For Laser Metal Deposition Processes, Sreekar Karnati, Niroop Matta, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser Metal deposition is a process with immense scope and promise for becoming a robust manufacturing technology in the near future. Monitoring process variables is very instrumental in process planning and output monitoring. The current work deals with realizing the effect of power modulation on size of the high temperature region during deposition with varying powder feed. A thermal camera was used to visualize and analyze the deposition process. The area of the high temperature region through the deposition was identified and compared to realize the effect of each variable parameter during deposition. The power modulation was fruitful in modulating …

Effect Of Architecture And Porosity On Mechanical Properties Of Borate Glass Scaffolds Made By Selective Laser Sintering, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Taylor Comte

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The porosity and architecture of bone scaffolds, intended for use in bone repair or replacement, are two of the most important parameters in the field of bone tissue engineering. The two parameters not only affect the mechanical properties of the scaffolds but also aid in determining the amount of bone regeneration after implantation. Scaffolds with five different architectures and four porosity levels were fabricated using borate bioactive glass (13-93B3) using the selective laser sintering (SLS) process. The pore size of the scaffolds varied from 400 to 1300 μm. The compressive strength of the scaffolds varied from 1.7 to 15.5 MPa …

Additive Manufacturing Laser Deposition Of Ti‐6al‐4v For Aerospace Repair Applications, Nanda Kumar Dey, Frank W. Liou, C. Nedic

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Parts or products from high performance metal are very expensive, partly due to the processing complexities during manufacturing. The purpose of this project is to use additive laser deposition and machining processes to repair titanium parts, thus extending the service life of these parts. The study broadly included preparing the defects, laser deposition, machining, sample preparation and mechanical tests. Comparative study of mechanical properties (UTS, YS, percentage elongation) of the repaired samples to the ideal conditions was undertaken. The research throws up interesting facts where the data from the test sample shows enhancement of properties of the repaired part.

Development Of Freeze-Form Extrusion Fabrication With Use Of Sacrificial Material, Ming-Chuan Leu, Diego A. Garcia

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The development of Freeze-form Extrusion Fabrication (FEF) process to fabricate three-dimensional (3D) ceramic parts with use of sacrificial material to build support sections during the fabrication process is presented in this paper. FEF is an environmentally friendly, additive manufacturing process that builds 3D parts in a freezing environment layer-by-layer by computer controlled extrusion and deposition of aqueous colloidal pastes based on computer-aided design (CAD) models. Methyl cellulose was identified as the support material, and alumina was used as the main material in this study. After characterizing the dynamics of extruding alumina and methyl cellulose pastes, a general tracking controller was …

Experimental Investigation Of Different Cellular Lattice Structures Manufactured By Fused Deposition Modeling, Osman Iyibilgin, Cemil Yigit, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Experimental tests were conducted to evaluate the compressive properties (yield strength and compressive modulus) and build time for five different cellular lattice structures fabricated by the Fused Deposition Modeling (FDM) process. The lattice structures had repeating unit cells, and the shapes of the unit cell under study included honeycomb, square, diamond, triangle, and circle. Test specimens were manufactured by a Stratasys Fortus 400mc machine using ABS (Acrylonitrile Butadiene Styrene) as the part material. The five different lattice structures were compared with each other and also with the sparse and sparse-double dense build styles that are directly available from the Fortus …

Dynamic Properties Of Fine-Grained Soils Engineered With A Controlled Organic Phase, B. Bate, H. Choo, S. E. Burns

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Soils with high organic content are frequently encountered beneath earthquake sensitive infrastructure, such as bridges or levees. Historically, the dynamic properties of these organically rich soils have been difficult to predict due to the heterogeneity of the natural organic matter that is found in natural soils, even though their response to dynamic loading remains critical to assessing the ongoing stability of the infrastructure. In this study, an experimental investigation was performed on a montmorillonite soil that was modified with a controlled organic phase. Quaternary ammonium cations were exchanged onto the soil particle surfaces through cation exchange with the clay's naturally …

Probabilistic Simulation Of Solidification Microstructure Evolution During Laser-Based Metal Deposition, Jingwei Zhang, Frank W. Liou, William Seufzer, Joseph William Newkirk, Zhiqiang Fan, Heng Liu, Todd E. Sparks

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A predictive model, based on a Cellular Automaton (CA) - Finite Element (FE) method, has been developed to simulate microstructure evolution during metal solidification for a laser based additive manufacturing process. The macroscopic FE calculation was designed to update the temperature field and simulate a high cooling rate. In the microscopic CA model, heterogeneous nucleation sites, preferential growth orientation and dendritic grain growth kinetics were simulated. The CA model was able to show the entrapment of neighboring cells and the relationship between undercooling and the grain growth rate. The model predicted the dendritic grain size, structure, and morphological evolution during …

Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Processes, Heng Liu, Todd E. Sparks, Frank W. Liou, David M. Dietrich

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct metal deposition (DMD) has gained increasing attention in the area of rapid manucooling rate, resulting in residual stresses and distortion. This paper presents a 3D sequentially coupled thermo-mechanical finite element model to predict residual stresses and deformations. The temperature distribution, thermal stress field and geometry deformation across domain are illustrated. The effect of deposition parameters on residual stress and deflections are also explored. A set of validation experiments for mechanical effects were conducted using laser displacement sensor. The comparisons between the simulated and experimental results show good agreement

Multiscaffold Dna Origami Nanoparticle Waveguides, William P. Klein, Charles N. Schmidt, Blake Rapp, Sadao Takabayashi, William B. Knowlton, Jeunghoon Lee, Bernard Yurke, William L. Hughes, Elton Graugnard, Wan Kuang

Electrical and Computer Engineering Faculty Publications and Presentations

DNA origami templated self-assembly has shown its potential in creating rationally designed nanophotonic devices in a parallel and repeatable manner. In this investigation, we employ a multiscaffold DNA origami approach to fabricate linear waveguides of 10 nm diameter gold nanoparticles. This approach provides independent control over nanoparticle separation and spatial arrangement. The waveguides were characterized using atomic force microscopy and far-field polarization spectroscopy. This work provides a path toward large-scale plasmonic circuitry.

Biofuel From Microalgae – A Review On The Current Status And Future Trends, Rajee Olaganathan, May Zaw Htet, Lim Yan Ling, Sek Hui Yun

Publications

The constant reliance on fossil fuel energy resources is unsustainable, due to both depleting world reserves and increasing green house gas emissions associated with their use and thus there are dynamic research at the global level envisioned at developing alternative renewable and potentially carbon neutral solid, liquid and gaseous biofuels as alternative energy resources. The contemporary knowledge and technology predictions have proved that among the third generation biofuels especially those derived from microalgae are considered the best reasonable alternative energy resource compared to undeniable drawbacks of first and second generation biofuels. Moreover, its efficiency to sequester carbon from the atmosphere …

Analysis Of Intervertebral Disc Degeneration Testing Method, David Williams, Dr. Anton Bowden

Journal of Undergraduate Research

This ORCA research project has focused on the determination of the effects of the order of the mechanical tests on the response of an intervertebral disc. We hypothesized that the order of the mechanical tests may influence the rate of diffusion of the Trypsin throughout the disc, affecting the biomechanical response. We have planned to determine the magnitude of this influence by using statistical techniques to analyze the data acquired. Virtually all of us (80 to 90 percent) will experience back pain in our lives. Low back pain is the leading cause of missed work days. The estimated economic impact …