Digital Commons Network^™

Transient Analysis Of Lumped Circuit Networks-Loaded Thin Wires By Dgtd Method, P. Li, Y. Shi, Lijun Jiang, H. Bagci

Electrical and Computer Engineering Faculty Research & Creative Works

With the purpose of avoiding very fine mesh cells in the proximity of a thin wire, the modified telegrapher’s equations (MTEs) are employed to describe the thin wire voltage and current distributions, which consequently results in reduced number of unknowns and augmented Courant–Friedrichs–Lewy (CFL) number. As hyperbolic systems, both the MTEs and the Maxwell’s equations are solved by the discontinuous Galerkin time-domain (DGTD) method. In realistic situations, the thin wires could be either driven or loaded by circuit networks. The thin wire–circuit interface performs as a boundary condition for the thin wire solver, where the thin wire voltage and current …

A Statistical Approach To Broadband Noise Suppression, Walter Eversman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A method for estimating achievable attenuation for broadband noise in an inlet duct, consistent with Dyer's suggestion that an appropriate model includes all propagating acoustic modes at equal power and random phase, is proposed. Broadband noise is represented in a frequency domain analysis by a statistical distribution of propagating duct modes. The required number of modes is estimated by Rice's approximation method and verified in FEM modeling. For each propagating circumferential mode propagating radial modes have equal acoustic power and random phase. Source acoustic power is distributed among circumferential modes according to the number of propagating radial modes in the …

Linear Burn Rates Of Monopropellants For Multi-Mode Micropropulsion, Alex J. Mundahl, Steven P. Berg, Joshua L. Rovey

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multi-mode micro propulsion is a potential game-changing technology enabling rapidly composable small satellites with unprecedented mission flexibility. Maximum mission flexibility requires propellant that is shared between the chemical and electric propulsion systems. Previous research has identified a promising monopropellant that is both readily catalytically exothermically decomposed (chemical mode) and electro sprayable (electric mode). In this work the linear burn rate of this monopropellant is determined to aid design of the microtube catalytic chemical thruster. A pressurized fixed volume reactor is used to determine the linear burn rate. Benchmark experiments use a 13-molar mixture of hydroxylammonium nitrate and water and show …

Output Feedback Adaptive Control With Low-Frequency Learning And Fast Adaptation, Tanmay Rajpurohit, Wassim M. Haddad, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although adaptive control has been used in numerous applications to achieve system performance without excessive reliance on system models, the necessity of high-gain learning rates for achieving fast adaptation can be a serious limitation of adaptive controllers. Specifically, in safety-critical systems involving large system uncertainties and abrupt changes in system dynamics, fast adaptation is required to achieve stringent tracking performance specifications. However, fast adaptation using high-gain learning rates can cause high-frequency oscillations in the control response, resulting in system instability. This paper develops an output feedback adaptive control framework for continuous-time minimum-phase multivariable dynamical systems for output stabilization and command …

Observation Of Late-Time Ablation In Electric Solid Propellant Pulsed Microthrusters, Matthew S. Glascock, Joshua L. Rovey, Shae Williams, Jason Thrasher

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Electric solid propellants are an interesting potential option for propulsion because they are ignited by an applied electric current. The electric nature of these materials leads to the capability for use in pulsed electric propulsion devices. In this work, the ablation process of an electric solid propellant during pulsed micro thruster operation is investigated using a triple Langmuir probe, thrust stand and high-speed video camera. Results include quantitative time-of-flight, ablation mass per pulse and impulse-per-pulse measurements. Additionally, qualitative images from the high-speed video are temporally correlated to these measurements. Analyses indicate 45±11% of the ablated mass per pulse is expelled …

Comparison Of Robust And Probabilistic Lmi-Based Design Of Adaptive Flight Controllers With Uncertain Input Dynamics, Mario Luca Fravolini, Tansel Yucelen, Benjamin Gruenwald, Merve Dogan, Marcello R. Napolitano

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Adaptive control-based schemes have been implemented to date in a variety of different ap-plications. However, the ability to obtain a predictable transient closed-loop performance in adaptive systems is still a challenging problem from a verification and validation point of view. To face this problem we have recently introduced an analysis and design framework for adaptive control systems in the presence of bounded uncertainty and bounded adaptive control (the boundedness can be enforced, for instance, by a parameter projection mechanism) showing that the transitory performance of a MRAC system can be expressed, analyzed, and optimized via a convex optimization formulation based …

Co-Doping Of Magnesium With Indium In Nitrides: First Principle Calculation And Experiment, Zhiqiang Liu, Binglei Fu, Xiaoyan Yi, Guodong Yuan, Junxi Wang, Jinmin Li, Luna, Ian Ferguson

Electrical and Computer Engineering Faculty Research & Creative Works

In this work, an effective strategy for achieving efficient p-type doping in wide bandgap nitride semiconductors was proposed to overcome the fundamental issue of high activation energy. We demonstrated that a hole concentration as high as 1.4 x 1018 cm-3 could been achieved through In-Mg co-doping. The electronic structure of the system and the formation energy of impurity were analyzed via first principal calculation to clarify the underlying physics and the ambiguity in understanding of the origin of the high hole concentration. Our results indicated that the original valence band maximum of the host materials could be modified, thus improving …

Electrostatically-Actuated 4h-Sic In-Plane And Out-Of-Plane High Frequency Mems Resonator, Allen V. Lim, Tutku Karacolak, Jheng Yi Jiang, Chih Fang Huang, Feng Zhao

Electrical and Computer Engineering Faculty Research & Creative Works

As a wide bandgap and single crystalline semiconductor, 4H-polytype silicon carbide (4H-SiC) is an excellent material choice for devices operating in harsh environments of high temperature, high pressure, radiation, chemical and biomedical, etc. In this letter, an electrostatically actuated 4H-SiC micro resonator was fabricated by dopant-selective photoelectrochemical etching of n-p-n homoepitaxial structure. Resonant frequencies of 3.463 MHz (out-of-plane) and 16.9 MHz (in-plane) were attained, and they are in good agreement with theoretical calculation. To the best of our knowledge, these frequencies are the highest values ever reported from single crystalline 4H-SiC MEMS resonators.

Effects Of Electrode Materials On Charge Conduction Mechanisms Of Memory Device Based On Natural Aloe Vera, Zhe Xi Lim, Sasidharan Sreenivasan, Yew Hoong Wong, Feng Zhao, Kuan Yew Cheong

Electrical and Computer Engineering Faculty Research & Creative Works

Resistive switching behaviors in Aloe vera films are being explored for nonvolatile memory applications. A simple structure in which the Aloe vera films sandwiched in between a top and bottom electrode are used. The switching behaviors of the devices in which the Aloe vera film is dried at different temperatures and the roles of top electrode materials (Al and Ag) are investigated. Current density-voltage measurements reveal that filamentary conduction is the dominant conduction process inducing resistive switching characteristics in Aloe vera films. Device with Al-Top electrode requires a forming voltage higher than devices with Ag-Top electrode, due to the tendency …

Convective Cooling In A Pool-Type Research Reactor, Susan Sipaun, Shoaib Usman

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A reactor produces heat arising from fission reactions in the nuclear core. In the Missouri University of Science and Technology research reactor (MSTR), this heat is removed by natural convection where the coolant/moderator is demineralised water. Heat energy is transferred from the core into the coolant, and the heated water eventually evaporates from the open pool surface. A secondary cooling system was installed to actively remove excess heat arising from prolonged reactor operations. The nuclear core consists of uranium silicide aluminium dispersion fuel (U₃Si₂Al) in the form of rectangular plates. Gaps between the plates allow coolant …

A Comprehensive Model Of The Transport Phenomena In Gas Metal Arc Welding, Junling Hu, Zhenghua Rao, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A comprehensive two-dimensional gas metal arc welding (GMAW) model was developed to take into account all the interactive events in the gas metal arc welding process, including the arc plasma, melting of the electrode, droplet formation, detachment, transfer, and impingement onto the workpiece, and the weld-pool dynamics and weld formation. The comprehensive GMAW model tracks the free surface using the volume of fluid method and directly modeled the coupling effects between the arc domain and the metal domain, thus eliminating the need to assign boundary conditions at the interface. A thorough investigation of the plasma arc characteristics was conducted to …

Learning Path Adaptivity In Support Of Flipped Learning: A Knowledge-Based Approach, Yu Liang Chi, Tsang Yao Chen

Business and Information Technology Faculty Research & Creative Works

Flipped learning inverts the two learning spaces of traditional education: the classroom group learning space and the homework individual learning space. In flipped learning, learners are exposed to direct instruction for basic knowledge acquisition before coming to the classroom for active learning with the teacher and peers. In recent years, flipped learning has received vast attention from educational practitioners and researchers. However, this study argues that existing e-learning systems mainly serve for learning management and content delivery purposes and lack support for flipped learning. As an innovative educational approach, flipped learning needs more pedagogical elements such as integrated instructional design …

Advances In Eye Tracking Technology: Theory, Algorithms, And Applications, Hong Fu, Ying Wei, Francesco Camastra, Pietro Arico, Hong Sheng

Business and Information Technology Faculty Research & Creative Works

No abstract provided.

Review Of Thomas Baldwin, James Fowler And Ana De Medeiros, Eds. Questions Of Influence In Modern French Literature. New York: Palgrave Macmillan, 2013., Audra L. Merfeld-Langston

Arts, Languages and Philosophy Faculty Research & Creative Works

Review of Thomas Baldwin, James Fowler and Ana de Medeiros, eds. Questions of Influence in Modern French Literature. New York: Palgrave Macmillan, 2013. xxvii + 223 pp.

Foucault Against Ethics: Subjectivity And Critique After Humanism, Patrick Gamez

Arts, Languages and Philosophy Faculty Research & Creative Works

This dissertation is in the first place an interpretation of the thought of Michel Foucault. Beyond interpretation, it also makes provides a qualified defense of his views on the significance of ethical theory, particularly in its “critical” forms, the shape of the space of reasons, and the role of subjectivity within it.

I take as my starting point an orthodox view of Foucault’s work, namely, that it can divided in terms of its content into three distinct periods. First, an “archaeological” phase spanning most of the 1960s. Second, a “genealogical” devoted to unearthing power-relations beneath purportedly progressive institutions. Finally, an …

An Integrated Completion And Reservoir Modeling Methodology For Horizontal Shale Wells: A Montney Formation Example, Rashid S. Kassim, Larry K. Britt, Shari Dunn-Norman, Bryan Lang

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Montney Formation is one of the largest unconventional resources in North America covering from southwestern Alberta to northeast British Columbia. The Montney Formation has natural gas, natural gas liquids (NGL) and oil from conventional and unconventional reservoirs. The first multiple fractured horizontal well (MFHW) was drilled in 2005. However, since the first MFHW, different methods were proposed to optimize completion designs in the Montney Formation. Some of the optimized completions utilized the "operational effectiveness" of high-rate slick-water fracture designs while other designs utilized energized fracturing fluids. What has been missing was an integrated methodology that utilizes all available data …

Laboratory Evaluation Of A Real-Time Coaxial Cable Casing Imager For Wellbore Integrity Monitoring, Yurong Li, Runar Nygaard, Baokai Cheng, Wenge Zhu, Hai Xiao

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Leakage is one of the major concerns in a geological carbon sequestration project due to the adverse environmental consequences. The main leakage risk of CO₂ through a thick, low permeable cap rock is identified to be along wells, especially in sedimentary basins that have a history of oil and gas exploration and production. To pursue a robust and cost-effective real-time monitoring technology for CO₂ leakage risk detection along the wellbore, a permanently downhole deployed coaxial cable casing imaging system is developed and tested for various deformation modes in laboratory in this paper. The casing imager consists of a …

Nitrogen Gas Flooding For Naturally Fractured Carbonate Reservoir: Visualisation Experiment And Numerical Simulation, Zhaojie Song, Jirui Hou, Zhongchun Liu, Fenglan Zhao, Shijun Huang, Yong Wang, Jieheng Wu, Baojun Bai

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Tahe Naturally Fractured Carbonate Reservoir has implemented nitrogen gas flooding since 2013, with daily oil production of 7580 bbls and oil recovery increment of 0.83% by the end of 2015. However, the presence of fractures significantly affects gas swept volume and production performance, so large amount of oil reserves is poorly flooded due to gas channeling through fractures. The fluid flow mechanisms in fractured models were discussed in order to improve field gas flooding efficiency. Based on the geological constrains of Tahe Oilfield, fractured models with different apertures were fabricated using acrylic glass to model carbonate matrix wettability and for …

Direct Experimental Evidence For Differing Reactivity Alterations Of Minerals Following Irradiation: The Case Of Calcite And Quartz, Isabella Pignatelli, Aditya Kumar, Kevin G. Field, Bu Wang, Yingtian Yu, Yann Le Pape, Mathieu Bauchy, Gaurav Sant

Materials Science and Engineering Faculty Research & Creative Works

Concrete, used in the construction of nuclear power plants (NPPs), may be exposed to radiation emanating from the reactor core. Until recently, concrete has been assumed immune to radiation exposure. Direct evidence acquired on Ar⁺-ion irradiated calcite and quartz indicates, on the contrary, that, such minerals, which constitute aggregates in concrete, may be significantly altered by irradiation. More specifically, while quartz undergoes disordering of its atomic structure resulting in a near complete lack of periodicity, calcite only experiences random rotations, and distortions of its carbonate groups. As a result, irradiated quartz shows a reduction in density of around …

Experimental Investigation Of Fracture Width Limitations Of Granular Lost Circulation Treatments, Mortadha Al-Saba, Runar Nygaard, Arild Saasen, Olav Magnar Nes

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Drilling fluid losses into fractured shales is a major challenge. Lost circulation treatments are widely applied to mitigate the losses; however, the effectiveness of these treatments is affected by different physical properties of the used lost circulation materials (LCM). This paper presents an experimental investigation to study the effect of LCM type, concentration, particle size distribution, temperature, and LCM shape on the formed seal integrity, with respect to differential pressure, at different fracture widths. The overall objective of this study is to address the effectiveness of LCM treatments in sealing fractured shales, with specific application to the over consolidated Barents …

Pumping Of Fresh Concrete: Insights And Challenges, Geert De Schutter, Dimitri Feys

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Pumping of Fresh Concrete is of Utmost Importance for Concrete Practice. Required Pumping Pressures Are Typically Estimated based on Design Charts. However, with the Increased Use of Chemical Admixtures and the Development of More Flowable Concrete Mixtures, the Accuracy of Traditional Design Charts is Questioned. in Recent Years, Significant Progress Has Been Obtained in Understanding the Flow of the Material in the Pumping Pipe, Including the Behavior of the Lubrication Layer Near the Pipe Surface. in Comparison with Traditional Design Charts, This Results in More Reliable Pressure Predictions When Considering Very Fluid Concrete Types Like Self-Consolidating Concrete. Some Remaining Challenges …

Gallium-Containing Mesoporous Bioactive Glass With Potent Hemostatic Activity And Antibacterial Efficacy, Sara Pourshahrestani, Ehsan Zeimaran, Nahrizul Adib Kadri, Nicola Gargiulo, Shani Samuel, Sangeetha Vasudevaraj Naveen, Tunku Kamarul, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Haemorrhage remains the leading cause of potentially survivable death in both military and civilian populations. Although a large variety of hemostatic agents have been developed, many of them have an inadequate capacity to induce hemostasis and are not effective in killing bacteria. In recent years, mesoporous bioactive glasses (MBGs) were found to be effective in inducing hemostasis. However, the materials may not be considered as ideal hemostats since they do not offer antimicrobial activity. The gallium ion (Ga⁺³) not only exhibits antibacterial properties but also accelerates the blood coagulation cascade. The aim of this study was to develop …

Antibacterial Properties Of Poly (Octanediol Citrate)/Gallium-Containing Bioglass Composite Scaffolds, Ehsan Zeimaran, Sara Pourshahrestani, Ivan Djordjevic, Belinda Pingguan-Murphy, Nahrizul Adib Kadri, Anthony W. Wren, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Bioactive glasses may function as antimicrobial delivery systems through the incorporation and subsequent release of therapeutic ions. The aim of this study was to evaluate the antimicrobial properties of a series of composite scaffolds composed of poly (octanediol citrate) with increased loads of a bioactive glass that releases zinc (Zn²⁺) and gallium (Ga³⁺) ions in a controlled manner. The antibacterial activity of these scaffolds was investigated against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The ability of the scaffolds to release ions and the subsequent ingress of these ions into hard tissue was evaluated …

Relating Ion Release And Ph To In Vitro Cell Viability For Gallium-Inclusive Bioactive Glasses, Timothy J. Keenan, L. M. Placek, T. L. Mcginnity, Mark R. Towler, M. M. Hall, A. W. Wren

Chemical and Biochemical Engineering Faculty Research & Creative Works

A bioactive glass (BG) in which Ga was substituted for Zn was formulated to investigate whether the ionic form of Ga can elicit effects similar to gallium nitrate. The ion release and pH of BG extracts were evaluated, as well as the in vitro cytocompatibility of extracts in contact with mouse fibroblasts and human osteoblasts. After incubation times of 1 year, the glass (TGa-1) containing the smaller Ga-addition (8 mol%) released the most sodium (Na) (1420 mg/L), silicon (Si) (221 mg/L), and Ga (1295 mg/L), while the glass (TGa-2) containing the larger Ga-addition (16 mol%), exhibited release levels between TGa-1, …

Inorganic Hemostats: The State-Of-The-Art And Recent Advances, Sara Pourshahrestani, Ehsan Zeimaran, Ivan Djordjevic, Nahrizul Adib Kadri, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hemorrhage is the most common cause of death both in hospitals and on the battlefield. The need for an effective hemostatic agent remains, since all injuries are not amenable to tourniquet use. There are many topical hemostatic agents and dressings available to control severe bleeding. This article reviews the most commonly used inorganic hemostats, subcategorized as zeolite and clay-based hemostats. Their hemostatic functions as well as their structural properties that are believed to induce hemostasis are discussed. The most important findings from in vitro and in vivo experiments are also covered.

Analysis Of The Developing States In The Mena Region Seeking Civilian Nuclear Energy, With A Primary Focus On The Kingdom Of Saudi Arabia (Ksa) And The United Arab Emirates (Uae), Thaqal Alhuzaymi, Ayodeji Babatunde Alajo

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

The comprehensive analysis presented here attempts to ana­lyze “newcomer” states in the Middle East and North Africa (MENA), primarily the Kingdom of Saudi Arabia (KSA) and Unit­ed Arab Emirates (UAE), seeking to implement civilian nuclear energy according to their political and economic situations. By investigating their motivations and funding resources for fu­ture nuclear projects, this analysis provides guidance for these states in terms of their nuclear infrastructure and nonprolifera­tion. The overall approach of this analysis relies on the factors for the success of civilian nuclear energy programs identified in experiential studies conducted since the Atoms for Peace speech in 1953.This …

Antibody Targeting Facilitates Effective Intratumoral Sirna Nanoparticle Delivery To Her2-Overexpressing Cancer Cells, Maria C. Palanca-Wessels, Garrett Booth, Anthony J. Convertine, Brittany B. Lundy, Geoffrey Y. Berguig, Michael F. Press, Patrick S. Stayton, Oliver W. Press

Materials Science and Engineering Faculty Research & Creative Works

The therapeutic potential of RNA interference (RNAi) has been limited by inefficient delivery of short interfering RNA (siRNA). Tumor-specific recognition can be effectively achieved by antibodies directed against highly expressed cancer cell surface receptors. We investigated the utility of linking an internalizing streptavidinconjugated HER2 antibody to an endosome-disruptive biotinylated polymeric nanocarrier to improve the functional cytoplasmic delivery of siRNA in breast and ovarian cancer cells in vitro and in an intraperitoneal ovarian cancer xenograft model in vivo, yielding an 80% reduction of target mRNA and protein levels with sustained repression for at least 96 hours. RNAi-mediated site specific cleavage …

Role Of Composition And Structure On The Properties Of Metal/Multifunctional Ceramic Interfaces, Fang Yin Lin, Aleksandr V. Chernatynskiy, Juan Claudio Nino, Jacob L. Jones, Richard G. Hennig, Susan Sinnott

Physics Faculty Research & Creative Works

The formation of intermetallic secondary phases, such as Pt₃Pb, has been observed experimentally at PbTiO₃/Pt and Pb(Zr,Ti)O₃/Pt, or PZT/Pt, interfaces. Density functional theory calculations are used here to calculate the work of adhesion of these interfacial systems with and without the secondary intermetallic phase. The charge density maps of the interfaces reveal the electronic interactions at the interface and the impact of the secondary phase. In addition, Bader charge analysis provides a quantitative assessment of electron transfer from the perovskites to the Pt. Analysis of the band diagrams indicates an increase of the potential …

Analysis Of The Cost Effectiveness Of Combined Particle And Activated Carbon Filters For Indoor Ozone Removal In Buildings, Josh R. Aldred, Erin Darling, Glenn Morrison, Jeffrey Siegel, Richard L. Corsi

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study involved the development of a model for evaluating the potential costs and benefits of ozone control with combined particle/activated carbon filtration (referred to here as activated carbon filtration) in buildings. The modeling effort included the prediction of indoor ozone and ozone reaction products with and without activated carbon filtration in the HVAC system. Benefitto- cost ratios were estimated for various types of buildings in 12 American cities in 5 different climate zones. Health benefits were evaluated using disability-adjusted life-years attributed to the difference in indoor ozone concentration with and without activated carbon filtration and included city-specific age demographics …

Electron Impact Ionization Dynamics Of Para-Benzoquinone, D. B. Jones, E. Ali, C. G. Ning, J. Colgan, O. Ingólfsson, Don H. Madison, M. J. Brunger

Physics Faculty Research & Creative Works

Triple differential cross sections (TDCSs) for the electron impact ionization of the unresolved combination of the 4 highest occupied molecular orbitals (4b_3g, 5b_2u, 1b_1g, and 2b_3u) of para-benzoquinone are reported. These were obtained in an asymmetric coplanar geometry with the scattered electron being observed at the angles −7.5°, −10.0°, −12.5° and −15.0°. The experimental cross sections are compared to theoretical calculations performed at the molecular 3-body distorted wave level, with a marginal level of agreement between them being found. The character of the ionized orbitals, through calculated momentum profiles, provides some qualitative …