Digital Commons Network^™

Functionalized Graphitic Nanoreinforcement For Cement Composites, Nima Zohhadi

Theses and Dissertations

Physical and mechanical properties of graphitic nanomaterials, in particular multiwalled carbon nanotubes (MWCNTs) and graphene nano-platelets (GNPs) make them promising candidates for nanoreinforcement of cement composites. The two key challenges associated with the incorporation of MWCNTs and GNPs are to attain uniform dispersion and interfacial bonding within the composite matrix. The effects of three main-stream dispersion techniques (namely, ultrasonication, acid-etching, and surfactant-coating) on the mechanical properties and microstructure of MWCNT- and GNP-cement composites were experimentally studied. Compressive strength tests and different characterization techniques including dynamic light scattering, Raman spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission …

Nitrogen Fertilizer, Cropping Systems, And Iowa Groundwater, Robert Dehaan, Ronald Vos, Matt Schuiteman, Matt Van Schouwen, Harlan Kruid

Faculty Work Comprehensive List

Summary presentation of research conducted over a 5 year period to determine which cropping systems best reduce nitrate leaching. Initial data was collected on nitrate concentration from individual wells in the Sioux Center, Iowa area which led to connections with the Iowa Department of Natural Resources Source Water Protection Program. A community group was then formed comprised of city representatives, Dordt College faculty, local farmers, Source Water Protection Program staff, and others. The group applied for and received a Leopold Center for Sustainable Agriculture grant to fund field experiments to identify cropping systems that retain nitrate and are workable for …

Research On Sealing Performance Of Hydrostatic Pressure Mechanical Seal, Wei-Bing Zhu, He-Shun Wang, Sheng-Ren Zhou

Journal of Marine Science and Technology–Taiwan

The hydrostatic pressure mechanical seal has many advantages, and it can be used in rotating machines with lower speed. Based on the externally pressurized stable gas lubrication theory, the control equation of end face flow field for hydrostatic pressure mechanical seal with orifice compensation was established. The functional extremum algorithm and the finite element method were used to solve this equation. The effects of gas film thickness, air supply pressure, throttle orifice number and diameter, on face opening force and gas film stiffness were discussed in detail. The results show that the opening force decreases with the widening of face …

Performance Evaluation Of Three Types Of Passive Micromixer With Convergent-Divergent Sinusoidal Walls, Arshad Afzal, Kwang-Yong Kim

Journal of Marine Science and Technology–Taiwan

A passive split-and-recombination micromixer with convergent-divergent channel walls of sinusoidal variation has been investigated using numerical simulations. With water and ethanol as working fluids, the analysis was performed using Navier-Stokes equations with convection-diffusion model in a Reynolds number range, 10  Re  70. Performances of three configurations with different split-and-recombination arrangements were evaluated in terms of mixing index and pressure drop. A parametric study was also conducted with two geometrical parameters, i.e., the ratios of throat-width to diameter of circular wall and diameter of circular wall to amplitude. The results showed a significant dependence of the mixing performance on …

Design Of A New Electromagnetic Valve With A Hybrid Pm/Em Actuator In Si Engines, Ly Vinh Dat, Yaojung Shiao

Journal of Marine Science and Technology–Taiwan

Numerous devices have been developed for controlling valve timings in SI engines. Among them, the electromagnetic valve train (EMV) actuator can fully control valve timings to improve fuel consumption and emission. In addition, an EMV with a permanent-magnet and electromagnetic-coil (PM/EM) hybrid actuator has several advantages of control, energy consumption, and time response compared over conventional EMVs. This paper proposes a novel EMV with a PM/EM hybrid actuator that differs considerably from existing EMVs. Finite element analysis was used for analyzing the EMV design. The optimization was based on criteria that ensured the EMV to satisfy holding forces in closed …

Effective Orifice Area Of A Newly Developed Polyurethane Aortic Valve: Manufacturing And Evaluation, Wu-Chiao Shih, Ha-Hai Vu, Cheung-Hwa Hsu, Kai-Wen Yang, Yaw-Hong Kang

Journal of Marine Science and Technology–Taiwan

An optimal design for a polyurethane (PU) aortic valve was developed in a previous study. The current study investigated an approach for manufacturing PU aortic valves, evaluating the effective orifice areas (EOAs) of the prototypes. Two manufacturing approaches, assembly and single-piece forming methods, were developed. In the assembly method, support frames and valve leaflets were manufactured separately and then glued together by using an adhesive substance. By contrast, in the single-piece forming method, two main components of the valve were fabricated simultaneously by using a molding technique. This study established an experimental loop that mimics natural circulation from the left …

Discoid And Asymmetrical Gyroless Micro-Satellite Off-Modulation Attitude Control With Kalman Filter, Ho-Nien Shou

Journal of Marine Science and Technology–Taiwan

The gyroless attitude control method and kalman algorithm procedures presented in this paper are applicable to asymmetrical microsatellites of any shape with large mass variation and without angular rate sensors. The attitude sensors include a three-axis magnetometer, a horizon sensor, and a coarse sun sensor (CSS), which together serve as an analytic platform and help in ensuring the stability of attitude controls. The attitude control problem of microsatellites has become a focal point because microsatellite fabrication processes are short, costless, and can be flexibly used for various purposes. The center of mass of the microsatellite can be offset because of …

Applying Fuzzy Logic Controller To Intelligent Solar Panel Cleaning System, Cong-Hui Huang

Journal of Marine Science and Technology–Taiwan

This paper presents an intelligent solar panel cleaning system that utilizes a fuzzy logic controller. The output voltage of the solar panel is applied to calculate whether to activate the cleaning mechanism. The direction and position of the system is set using a light sensor that is parallel to the direction of the sunlight. The data from the light sensors, combined with fuzzy logic control software developed using LabVIEW, determine the control commands (stop, forward, and reverse) for the stepper motors controlling the cleaning process. The cleaning process, which is repeated until the power output from the solar panels is …

Synthetic Physical Models For Animating Unsteady Fish Motions, Shyh-Kuang Ueng, Hong-Kai Chen

Journal of Marine Science and Technology–Taiwan

This paper presents physical models for simulating unsteady fish motions, including bursting, gliding, braking, turning, ascending and descending. A new wave model, the controllable body wave model, is developed to undulate the fish body to produce bursting and gliding motions. A key frame approach is adopted to realize braking, turning, descending and ascending. In the key frame method, individual motions are decomposed into sequences of key steps. The gestures of the fish in these key steps are recorded and regarded as key frames. In the run time, these recorded key frames are sequentially reproduced to generate swimming patterns. In addition …

Modeling And Control Of A Novel Ball Screw Mechanism, Wen-Hsiang Hsieh, Kai-Bi Chang

Journal of Marine Science and Technology–Taiwan

This study proposes a systematic approach for the design and control of a novel ball screw transmission system. We investigated the structure of the system, performed kinematic analysis, and conducted dimensional synthesis by optimization. The mathematical model of the system was determined by system identification and a refined PID controller was designed. Computer simulation was conducted to verify the feasibility of the proposed design. A prototype machine and an experimental setup were built and tested. The experimental results show that the output with the controller agrees well with the required output. Therefore, the proposed design can produce the expected output …

Fault Diagnosis And Performance Assessment For A Rotary Actuator Based On Neural Network Observer, Jian Ma, Xin Li, Chen Lu, Zi-Li Wang

Journal of Marine Science and Technology–Taiwan

Substantial damage may occur when a rotary actuator fails during operation. Therefore, effective fault diagnosis of a rotary actuator is crucial to ensuring the safety of the device. However, only a few studies on fault detection, fault isolation, and performance assessment have focused on rotary actuators. In this study, fault detection and fault isolation processes were implemented by designing two observers based on a neural network, and a method that assesses the performance of the rotary actuator is proposed. First, two observers are established according to the structure of the rotary actuator. Data in their normal state are used to …

Analysis Of Heart Rate Variability Amongst Cyclists Under Perceived Variations Of Risk Exposure, Ronan Doorley, Vikram Pakrashi, Eoin Byrne, Samuel Comerford, Bidisha Ghosh, John A. Groeger

NIMBUS Articles

Cycling as a mode of travel provides an opportunity for many people to increase their levels of regular physical activity and contribute to their mental and physical health. Heart rate is often used as a means of measuring the intensity and energy expenditure of physical activity. However, heart rate is also linked to emotional factors such as anxiety and fear. Perceptions of risk due to external factors such as other road users and infrastructure may arouse such emotions in urban cyclists. The present study set out to investigate whether or not perceptions of risk among urban cyclists may lead to …

How The Esa Can Swallow Alaskan Tribal Sovereignty: The Story Of The Iliamna Lake Seals, Charisse Arce

American Indian Law Journal

No abstract provided.

Fundamentals Of Contracting By And With Indian Tribes, Michael P. O'Connell

American Indian Law Journal

No abstract provided.

Building Sanity: The Rise And Fall Of Architectural Treatment At The South Carolina Lunatic Asylum, Kimberly Jean Campbell

Theses and Dissertations

Although many historians have acknowledged the importance of architecture in the treatment of the mentally ill during the nineteenth century, no historian has ever examined the rise and fall of the importance of architecture to the treatment of patients at the South Carolina Lunatic Asylum. By the late eighteenth century, physicians and laymen alike accepted the ideology of environmental determinism – that one’s environment exercised a direct influence over his or her behavior. In other words, mental illness was both caused and cured by the environment; thus, architecture played a key role in the treatment of mental illness. The South …

Science Fairs Before Sputnik: Adolescent Scientific Culture In Contemporary America, Sarah Michel Scripps

Theses and Dissertations

"Science Fairs before Sputnik: Adolescent Scientific Culture in Contemporary America" traces the formation and evolution of science fairs in America, focusing on the ways in which adolescents established communities of practice by engaging in these competitions. Over the course of the twentieth century, generations of American children conducted their first experiments by crafting science fair projects. The dissertation evaluates this understudied phenomenon against the backdrop of American fascinations and fears of science and evolving notions of adolescence. It argues that science fairs were central to shaping an adolescent scientific culture in the United States during the early to mid twentieth …

Saint Dominguan Refugees In Charleston, South Carolina, 1791-1822: Assimilation And Accommodation In A Slave Society, Margaret Wilson Gillikin

Theses and Dissertations

During the 1790s and the first decade of the nineteenth century, nearly 20,000 refugees fled the French colony of Saint Domingue for asylum in the United States. They found new homes in such American port cities as New York, Philadelphia, Baltimore, Charleston, and New Orleans. This dissertation explores the experiences of the white planters, gens de couleur, and slaves who sought asylum in Charleston, South Carolina, and the effect their presence had on the city’s long time residents. It might seem from first glance that finding acceptance in Charleston would be easy for them, but this was not the case. …

Joint Representation Of Translational And Rotational Components Of Self-Motion In The Parietal Cortex, Adhira Sunkara

McKelvey School of Engineering Graduate Student Theses & Dissertations

Navigating through the world involves processing complex visual inputs to extract information about self-motion relative to one's surroundings. When translations (T) and rotations (R) are present together, the velocity patterns projected onto the retina (optic flow) are a combination of the two. Since navigational tasks can be extremely varied, such as deciphering heading or tracking moving prey or estimating one's motion trajectory, it is imperative that the visual system represent both the T and R components. Despite the importance of such joint representations, most previous studies have only focused on the representation of translations. Moreover, these studies emphasized the role …

Aerosol Techniques For Deposition And Characterization Of Biological And Biomimetic Sensitizers For Solar Devices, Vivek B. Shah

McKelvey School of Engineering Graduate Student Theses & Dissertations

Nano-structured columnar films synthesized by the aerosol chemical vapor deposition (ACVD) system are unique, and have proved to be useful for fabricating solar cells and in other applications. The film formation by ACVD process involves three main phenomenon - aerosol formation and growth, deposition, and restructuring. In this work, thin film formation by the ACVD process is simulated by combining three models - (A) particle formation in gas phase by atrimodal model, (B) particle deposition onto heated substrate by a Brownian dynamics model and (C) sintering on the heated substrate by a multi-particle geometric sintering model (MPGSM). Modelling and simulation …

Childhood Poverty And Psychological Health Of Youths In Hong Kong: Mentoring As A Social Capital Intervention, Hor Yan Lai

Arts & Sciences Graduate Student Theses and Dissertations

Considering that one out of five youths live in poverty in Hong Kong, and poverty is found to have a negative impact on youths' psychological well-being, this dissertation proposes mentoring as a social capital intervention to improve the psychological health of these young people, both who are locally born and who immigrated from Mainland China. In this dissertation, mentoring is defined as a social capital intervention that changes the social resources available to youths living in poverty, and such changes enhance young people's positive psychological outcomes. Based on the social capital theory, poverty-related and psychological theories, three aims were formulated. …

A Reinforcement-Learning Framework For Interpreting Trial-By-Trial Motor Adaptation To Novel Haptic Environments, Ranjan Patrick Khan

McKelvey School of Engineering Graduate Student Theses & Dissertations

Motor adaptation is often considered to occur under the influence of sensory signals, which is usually readily available for humans performing most motor tasks. However, humans can also use reward or other qualitative feedback to reinforce previous actions and perform adaptation. In these experiments, we introduce reward feedback to a traditional motor adaptation experiment: reach adaptation to a velocity-dependent force field. Drawing from the literature of computer science and machine learning, we use a reinforcement-learning framework to interpret the pattern of force generation and reward-prediction errors and observe the effects of concurrent and isolated reward and sensory feedback.

It is …

Approximation And Relaxation Approaches For Parallel And Distributed Machine Learning, Stephen Tyree

McKelvey School of Engineering Graduate Student Theses & Dissertations

Large scale machine learning requires tradeoffs. Commonly this tradeoff has led practitioners to choose simpler, less powerful models, e.g. linear models, in order to process more training examples in a limited time. In this work, we introduce parallelism to the training of non-linear models by leveraging a different tradeoff--approximation. We demonstrate various techniques by which non-linear models can be made amenable to larger data sets and significantly more training parallelism by strategically introducing approximation in certain optimization steps.

For gradient boosted regression tree ensembles, we replace precise selection of tree splits with a coarse-grained, approximate split selection, yielding both faster …

Toward Improved Computational Tools For Electronic Transport Analysis And Their Use In The Development Of Materials For Energy Applications, Maria Stoica

McKelvey School of Engineering Graduate Student Theses & Dissertations

With the rapid rise in computational speed and capacity of massively parallel computing clusters in recent years, theoretical screening of large, previously unexplored sets of complex compounds to find materials with a given set of desired properties is quickly becoming a reality. In order to maximize the predictive ability of these large-scale computations, it is desirable to develop accurate post-processing algorithms that can efficiently manipulate electronic structure data to produce theoretical predictions of experimentally observable quantities. To address this need, the work of this dissertation has been to expand existing \textit{ab initio} methods for determining electronic properties of bulk complex …

Infant Mortality: Cross Section Study Of The United State, With Emphasis On Education, Daniel C. Sheets-Poling

Student Research – Stevenson Center

On the surface infant mortality is usually thought of as just a unfortunate part of life in what can happen to an individual family, but infant mortality is part of the factors that affect social capital, which can lead back to overall trust in a community. When that trust starts to wither within a community, economic activity will be affected as community members will not behave as they usually do within their given economic boundaries. While social capital is not solely affected by infant mortality, it does show what type of health status an area has. As a community, state, …

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My News (2014-2020)

• 1,700 Degrees Conferred During Fall Commencement
• Willie Fritz Named 2014 Coach of the Year
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• Purchase Football Game Programs from Historic Championship Season
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• Final "My News" of 2014
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• Take Advantage of University Store Savings This Week

Integrating The Arts And Sciences In The Museum Setting, Emily Clare Riggins

Seton Hall University Dissertations and Theses (ETDs)

The division between the arts and sciences appears to be deepening in America. As political leaders emphasize STEM (science, technology, engineering and math) education in schools, arts education is diminished to make room for STEM courses. Concerned about this phenomenon, many art educators are working to integrate the arts into STEM education through a variety of arts integration efforts. Arts integration not only helps to preserve a place for the arts in the curriculum, it also has been shown to enhance STEM learning.

Arts integration is of special interest to art museum educators who feel that they can provide resources …

Real-Time Temperature Imaging Using Ultrasonic Change In Backscattered Energy, Weiyuan Zhao

McKelvey School of Engineering Graduate Student Theses & Dissertations

Thermal therapy from low-temperature cryosurgery to high-temperature ablation of tumors and unwanted electrical pathways has gained increased attention. Temperature imaging (TI) from magnetic resonance studies is the de facto standard for volumetric estimation of temperature. Ultrasound has the advantages of being cheap, portable, non-invasive and non-ionizing. Our group showed in predictions for single scatterers, simulations of scatterer populations and measurements in 1D, 2D and 3D, that CBE changed monotonically with temperature with 1^oC accuracy. An obstacle to clinical application of CBE TI is estimation of temperature in real time, which is limited by time for motion compensation (MC). …

The Effects Of Gamifying Optional Lessons On Motivation, Aaron Zemach

McKelvey School of Engineering Graduate Student Theses & Dissertations

Adding video-game elements to non-video-game interfaces (“gamification”) has become a common engagement strategy over the past several years in the domain of education. While prior studies have found that adding game elements to mandatory educational materials can increase students’ motivation to complete the materials, there has yet to be a study to investigate if game elements can make users more likely to engage with optional educational materials. In this study, we investigate whether users of a gamified educational interface are more motivated than users of a non-gamified interface to voluntarily complete educational materials. We found users of a gamified interface …

Modeling Algorithm Performance On Highly-Threaded Many-Core Architectures, Lin Ma

McKelvey School of Engineering Graduate Student Theses & Dissertations

The rapid growth of data processing required in various arenas of computation over the past decades necessitates extensive use of parallel computing engines. Among those, highly-threaded many-core machines, such as GPUs have become increasingly popular for accelerating a diverse range of data-intensive applications. They feature a large number of hardware threads with low-overhead context switches to hide the memory access latencies and therefore provide high computational throughput. However, understanding and harnessing such machines places great challenges on algorithm designers and performance tuners due to the complex interaction of threads and hierarchical memory subsystems of these machines. The achieved performance jointly …

Metabolic Engineering Of Cyanobacteria For Photosynthetic Production Of Drop-In Liquid Fuels, Bertram Michael Berla

McKelvey School of Engineering Graduate Student Theses & Dissertations

Cyanobacteria are oxygenic phototrophs with great potential as hosts for renewable fuel and chemical production. They grow very quickly (compared with plants) and can use sunlight for energy and CO2 as a carbon source (unlike yeast or E. coli). While cyanobacteria have been engineered to make many chemicals that are native and non-native parts of their metabolism, this work is concerned with the production of heptadecane in Synechocystis sp. PCC 6803. Heptadecane is in a class of natural products produced by all cyanobacteria, but in quantities insufficient for industrialization. Towards this future goal, we have built enabling systems for the …