Digital Commons Network^™

Investigation Of Lost Circulation Materials Impact On Fracture Gradient, Mortadha Turki Alsaba

Doctoral Dissertations

"Lost circulation is a challenging problem to be prevented or mitigated during drilling. Lost circulation treatments are widely applied to mitigate losses using a corrective approach or to prevent losses using preventive approaches, also known as "wellbore strengthening". The disagreement among the different wellbore strengthening theories and the lack of understanding the strengthening mechanism resulted in the absence of a standardized method to evaluate the effectiveness of lost circulation materials (LCM) for wellbore strengthening application.

An extensive experimental investigation was performed by constructing a high pressure LCM test apparatus to investigate the effects of different parameters on the sealing efficiency …

Linear Precoding For The Mimo Multiple Access Channel With Finite Alphabet Inputs And Statistical Csi, Yongpeng Wu, Chao Kai Wen, Chengshan Xiao, Xiqi Gao, Robert Schober

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we investigate the design of linear precoders for the multiple-input-multiple-output (MIMO) multiple access channel (MAC). We assume that statistical channel state information (CSI) is available at the transmitters and consider the problem under the practical finite alphabet input assumption. First, we derive an asymptotic (in the large system limit) expression for the weighted sum rate (WSR) of the MIMO MAC with finite alphabet inputs and Weichselberger's MIMO channel model. Subsequently, we obtain the optimal structures of the linear precoders of the users maximizing the asymptotic WSR and an iterative algorithm for determining the precoders. We show that …

Defensive Routines In Engineering Managers And Non-Engineering Managers -- A Case Analysis, Tyria Riley, Elizabeth A. Cudney

Engineering Management and Systems Engineering Faculty Research & Creative Works

There is a perception that engineers experience challenges in areas such as communication, conflict resolution, and leadership. Defensive routines are actions implemented as a result of being in an embarrassing or threatening situation. This research uses a case study approach to measure whether defensive routines are more common in engineering managers or non-engineering managers. Twenty-seven managers created case studies based on their unique experiences as managers. These case studies were scored, and the results of this research indicate that engineering managers employ defensive routines more commonly than non-engineering managers.

Strategies To Enhance Learning In A Large Engineering Economics Course: Including Students’ Perceived Values In The Instructional Redesign Process, Kellie S. Grasman, D. Cernusca

Engineering Management and Systems Engineering Faculty Research & Creative Works

Purposeful implementation of technology in instructional design presents opportunities to increase institutional efficiency while simultaneously improving instructional quality. This paper presents findings from the implementation of a hybrid/buffet approach in an undergraduate Engineering Economics large course. A Design-Based Research (DBR) approach informed the instructional redesign and measured its effectiveness through multiple iterations, or macro-cycles, of implementation. Overall, pedagogical structure and specific technology solutions applied to each course component are described, as well as preliminary measures of effectiveness and student perception from a pilot offering of the hybrid/buffet course. Encouraged by positive preliminary results, a second implementation informed further study of …

An Integrated Study For Hybrid Composite Beam (Hcb) Structures, Mohamed Abdelkhalik Aboelseoud

Doctoral Dissertations

"The hybrid composite beam (HCB) consists of a self consolidating concrete (SCC) arch that is tied at the end by galvanized strands. The tied arch is encapsulated by a glass fiber reinforced polymer (GFRP) shell. A limited number of researches have studied the essential design methodologies and long-term performance of the HCB. The research presented in this dissertation aimed to more fundamentally understand the structural behavior of this new beam and evaluate its durability. This research study was conducted through four phases. A full-scale bridge load testing was conducted on a single-web HCB bridge during the first phase. The first …

The Relative Effect Of Charge Dimensions On Elastic Vibration Attenuation And Blast-Induced Seismic Energy Concepts, Nathan Thomas Rouse

Doctoral Dissertations

"This dissertation focuses on expanding the blasting industry's current understanding of the effect of charge geometry on blast vibration attenuation. The work includes a multiple regression analysis of a sample population of signature hole blast vibration data. The regression analysis is used to identify the relative effect of the variables that affect blast vibrations at various distances from the charge. The study suggests that the most common vibration models used in the blasting industry do not use all of the statistically significant variables. Therefore, the models neglect to fully describe the relationship between the significant variables and the blast vibration. …

Detection And Removal Of Emerging Environmental Contaminants, Ruipu Mu

Doctoral Dissertations

"Water is a very crucial natural resource for human. The increasing number of contaminants detected in water bodies has drawn considerable increasing attention over the last decade. There are numerous emerging environmental contaminants which may cause serious health issues. The recent occurrence studies of these contaminants show both industrial and household activity introduction of chemicals into water resources. These various sources result in a large variety of chemicals such as explosives, pharmaceutical and personal care products (PPCPs) and disinfection byproducts detected in water worldwide. Due to the relatively low contaminant concentrations, development of new and improved detection methods along with …

On Testing Common Indices For Several Multi-Index Models: A Link-Free Approach, Xuejing Liu

Doctoral Dissertations

"To avoid the curse of dimensionality, and to help us better understand the structure of the high dimensional data, methods for dimension reduction are clearly called for. The common linear dimension reduction techniques for single population include principal component analysis (PCA) which is unsupervised in regression and supervised Partial Least Squares (PLS). Modern sufficient dimension reduction techniques, like the ones we consider, constitute a form of supervised linear dimension reduction which outperform PCA and PLS without the underlying model assumptions.

In practice, we often deal with situations where the same variables are being measured on objects from different groups, and …

Quantum Inspired Algorithms For Learning And Control Of Stochastic Systems, Karthikeyan Rajagopal

Doctoral Dissertations

"Motivated by the limitations of the current reinforcement learning and optimal control techniques, this dissertation proposes quantum theory inspired algorithms for learning and control of both single-agent and multi-agent stochastic systems.

A common problem encountered in traditional reinforcement learning techniques is the exploration-exploitation trade-off. To address the above issue an action selection procedure inspired by a quantum search algorithm called Grover's iteration is developed. This procedure does not require an explicit design parameter to specify the relative frequency of explorative/exploitative actions.

The second part of this dissertation extends the powerful adaptive critic design methodology to solve finite horizon stochastic optimal …

Small Signal Modeling And Analysis Of Microgrid Systems, Md. Rasheduzzaman

Doctoral Dissertations

This dissertation focuses on small-signal modeling and analysis of inverter based microgrid systems. The proposed microgrid consists of two microsources placed on two different buses. The buses are connected using a distribution feeder with some impedance. The proposed microgrid can operate with the grid support, or without the grid support. When operated without the grid support, the standalone system’s microsources participate in controlling the system voltage and frequency. For a non-inertia source, such as the inverter, the load perturbations play an important role in system dynamics. In paper-I, such complex system was studied.

In the grid-tied mode, the microsources share …

Privacy-Preserving Query Processing Over Encrypted Data In Cloud, Yousef M. Elmehdwi

Doctoral Dissertations

"The query processing of relational data has been studied extensively throughout the past decade. A number of theoretical and practical solutions to query processing have been proposed under various scenarios. With the recent popularity of cloud computing, data owners now have the opportunity to outsource not only their data but also data processing functionalities to the cloud. Because of data security and personal privacy concerns, sensitive data (e.g., medical records) should be encrypted before being outsourced to a cloud, and the cloud should perform query processing tasks on the encrypted data only. These tasks are termed as Privacy-Preserving Query Processing …

Quantification Of Information Flow In Cyber Physical Systems, Li Feng

Doctoral Dissertations

"In Cyber Physical Systems (CPSs), traditional security mechanisms such as cryptography and access control are not enough to ensure the security of the system since complex interactions between the cyber portion and physical portion happen frequently. In particular, the physical infrastructure is inherently observable; aggregated physical observations can lead to unintended cyber information leakage. Information flow analysis, which aims to control the way information flows among different entities, is better suited for CPSs than the access control security mechanism. However, quantifying information leakage in CPSs can be challenging due to the flow of implicit information between the cyber portion, the …

Approximation Methods In Relativistic Eigenvalue Perturbation Theory, Jonathan Howard Noble

Doctoral Dissertations

"In this dissertation, three questions, concerning approximation methods for the eigenvalues of quantum mechanical systems, are investigated: (i) What is a pseudo-Hermitian Hamiltonian, and how can its eigenvalues be approximated via numerical calculations? This is a fairly broad topic, and the scope of the investigation is narrowed by focusing on a subgroup of pseudo-Hermitian operators, namely, PT-symmetric operators. Within a numerical approach, one projects a PT-symmetric Hamiltonian onto an appropriate basis, and uses a straightforward two-step algorithm to diagonalize the resulting matrix, leading to numerically approximated eigenvalues. (ii) Within an analytic ansatz, how can a relativistic Dirac Hamiltonian be …

Non-Destructive And Destructive Bridge Deck Condition Assessment, Aleksandra V. Varnavina

Doctoral Dissertations

"The dissertation is composed of three papers, which cover the lack of information on the specific aspects of non-destructive and destructive bridge deck assessment.

In the first paper, appropriate data acquisition and processing parameters for concrete bridge deck condition assessment using ground-coupled ground penetrating radar are developed. The use of proposed parameters helps to significantly reduce acquisition and processing time, while providing engineers with reliable and detailed information on the condition of bridge deck.

In the second paper, a novel approach to develop relationship between GPR data and concrete removal depth measurements collected after hydrodemolition is proposed. A linear relationship …

Numerical Study On Scaling Effects And Decoupled Network-Based Simulation Of Gaseous Explosion, Liang Wang

Doctoral Dissertations

"This research seeks to improve the prediction efficiency of gaseous explosions realized by numerical simulations in a full-scale underground network using a decoupled method. To provide quick predictions of overpressure distribution of methane explosions in underground airway networks, a two-section theory is employed. The explosion space is divided into a driver section and a blast-wave section. Governing equations including conservation of mass, momentum, and energy, together with chemical reaction and turbulence models are solved for the driver and the blast-wave sections using computational fluid dynamics (CFD) solver ANSYS Fluent (3D-based) and Flowmaster (1D-based) respectively. The three dimensional (3D) and one …

Evaluation Of Nickel-Titanium Oxide-Niobium Pentoxide Metal Ceramic Composite As Interconnect For Solid Oxide Fuel Cell, Abhijith Budur

Masters Theses

"With increasing importance for clean energy, fuel cells have gained great significance in recent decades. Solid oxide fuel cells are easy to transport due to presence of solid electrolyte and also have requisite electrical properties,but have been obstructed by their limitation to be used at only temperatures greater than 600⁰C and less than 800⁰C. To construct a stack of cells, materials that are good electrical conductors and having necessary mechanical strengths at that temperatures are being considered as interconnects between the cells. Evaluation of Nickel-Titanium dioxide-Niobium pentoxide (NTN) as interconnect and comparison to Stainless Steel 441 alloy has been made …

Day Of The Week Effect In Returns And Volatility Of The S&P 500 Sector Indices, Juan Liu

Masters Theses

"Previous studies have shown that returns associated with the stock market or foreign exchange's futures show variations across the day of the week. On such study, that employs a modified GARCH model for estimation, shows that returns associated with the S&P 500 stock index is highest on Wednesday and lowest returns on Monday. The same study shows that volatility is highest on Fridays and lowest on Wednesdays. In this study we investigate if this day-of-the-week effect on returns and volatility is present in the different sectors that constitute the S&P 500 index. The data set used provides daily returns from …

The Development Of Near Field Probing Systems For Emc Near Field Visualization And Emi Source Localization, Hui He

Masters Theses

"The objectives of this research are to visualize the frequency dependent electromagnetic field distribution for electromagnetic compatibility (EMC) applications and the radiating source reconstruction on complex shaped electronic systems. This is achieved by combining near field probing with a system for automatically recording the probe position and orientation. Due to the complexity of the shape of the electronic systems of interest, and for utilizing the expertise of the user, the probe will be moved manually not robotically. Concurrently, the local near field will be recorded, associated with the location and displayed at near real time on the captured 3D geometry …

Sensitivity Of Cellular Oxidative Damage To Biosynthetic Rate And Metabolic Rate, Palihawadana Walauwe Kamalika Kaushalya Amunugama

Masters Theses

"The relationship between energy expenditure and longevity is a long standing question in aging studies. The empirical results have contradictory effects on the existing theories. A theoretical model and an experimental test of it were presented, revealing the detailed tradeoffs between metabolic rate, biosynthetic rate and cellular damage level. The dissipative mechanisms of oxidative metabolism cause various forms of cellular damages. To counteract the accumulation of damage, organisms have evolved highly efficient maintenance mechanisms. If there is no other energy demand possess, then most of the cellular damage would be repaired, regardless of how metabolic rate varies. However, the repairing …

Developing A Novel Methodolgy And Testbed For Fatigue Analysis Of Metal Specimens, Sai Aravind Palepu

Masters Theses

"A prototype of fatigue testing machine was built to determine the fatigue strength of materials. Proposed testing prototype was displacement controlled magnetic type bend fatigue testing machine. Designed prototype was tuned to operate at or near resonance of the specimen in order to amplify excitation displacement. Low maintenance i.e. zero wear of the parts was achieved, there were no moving components in the prototype machine. Crucial components used to build were: DC power supply, solenoid, Arduino UNO, supports and laser displacement sensor. DC source used to pass current through solenoid producing magnetic field; mosfet and Arduino generated square waves of …

Photoelectron Spectroscopic And Computational Study Of Hydrated Pyrimidine Anions, John T. Kelly, Shoujun Xu, Jacob Graham, J. Michael Nilles, Dunja Radisic, Angela M. Buonaugurio, Kit H. Bowen, Nathan I. Hammer, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The stabilization of the pyrimidine anion by the addition of water molecules is studied experimentally using photoelectron spectroscopy of mass-selected hydrated pyrimidine clusters and computationally using quantum-mechanical electronic structure theory. Although the pyrimidine molecular anion is not observed experimentally, the addition of a single water molecule is sufficient to impart a positive electron affinity. The sequential hydration data have been used to extrapolate to -0.22 eV for the electron affinity of neutral pyrimidine, which agrees very well with previous observations. These results for pyrimidine are consistent with previous studies of the hydrated cluster anions of uridine, cytidine, thymine, adenine, uracil, …

Contributions Of Unique Active Site Residues Of Eukaryotic Udp-Galactopyranose Mutases To Substrate Recognition And Active Site Dynamics, Isabel Da Fonseca, Insaf A. Qureshi, Ritcha Mehra-Chaudhary, Karina Kizjakina, John J. Tanner, Pablo Sobrado

Chemistry Faculty Research & Creative Works

UDP-glucopyranose mutase (UGM) catalyzes the interconversion between UDP-galactopyranose and UDP-galactofuranose. Absent in humans, galactofuranose is found in bacterial and fungal cell walls and is a cell surface virulence factor in protozoan parasites. For these reasons, UGMs are targets for drug discovery. Here, we report a mutagenesis and structural study of the UGMs from Aspergillus fumigatus and Trypanosoma cruzi focused on active site residues that are conserved in eukaryotic UGMs but are absent or different in bacterial UGMs. Kinetic analysis of the variants F66A, Y104A, Q107A, N207A, and Y317A (A. fumigatus numbering) show decreases in kcat/KM values of 200-1000-fold for the …

A Revisit Of The Equilibrium Assumption For Predicting Near-Wall Turbulence, Farid Karimpour, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this study, we revisit the consequence of assuming equilibrium between the rates of production (P) and dissipation (∈) of the turbulent kinetic energy (k) in the highly anisotropic and inhomogeneous near-wall region. Analytical and dimensional arguments are made to determine the relevant scales inherent in the turbulent viscosity (νt) formulation of the standard k-∈ model, which is one of the most widely used turbulence closure schemes. This turbulent viscosity formulation is developed by assuming equilibrium and use of the turbulent kinetic energy (k) to infer the relevant velocity scale. We show that such turbulent viscosity formulations are not suitable …

Getting Down To The Fundamentals Of Hydrogen Bonding: Anharmonic Vibrational Frequencies Of (Hf)2 And (H2o)2 From Ab Initio Electronic Structure Computations, J. Coleman Howard, Jessica L. Gray, Amanda J. Hardwick, Linh T. Nguyen, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

This work presents a systematic investigation into the basis set convergence of harmonic vibrational frequencies of (H₂O)₂ and (HF)₂ computed with second-order Møller-Plesset perturbation theory (MP2) and the coupled-cluster singles and doubles method with perturbative connected triples, CCSD(T), while employing correlation-consistent basis sets as large as aug-cc-pV6Z. The harmonic vibrational frequencies presented here are expected to lie within a few cm^-1 of the complete basis set (CBS) limit. For these important hydrogen-bonding prototype systems, a basis set of at least quadruple-ζ quality augmented with diffuse functions is required to obtain harmonic vibrational frequencies within 10 …

The Missouri Miner, December 4, 2014

The Missouri Miner Newspaper

No abstract provided.

Physiological Effects And Therapeutic Potential Of Proinsulin C-Peptide, Gina L.C. Yosten, Christine Maric-Bilkan, Patrizia Luppi, John Wahren

Biological Sciences Faculty Research & Creative Works

Connecting Peptide, or C-peptide, is a product of the insulin prohormone, and is released with and in amounts equimolar to those of insulin. While it was once thought that C-peptide was biologically inert and had little biological significance beyond its role in the proper folding of insulin, it is now known that C-peptide binds specifically to the cell membranes of a variety of tissues and initiates specific intracellular signaling cascades that are pertussis toxin sensitive. Although it is now clear that C-peptide is a biologically active molecule, controversy still remains as to the physiological significance of the peptide. Interestingly, C-peptide …

Stability Design Criteria For Distribution Systems With Solid-State Transformers, Darshit G. Shah, M. L. Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Due to recent advancements in semiconductor technology, power-electronic converters for high-voltage, high-power, and high-frequency applications will soon be commercially available. The theoretical concept of a distribution solid-state transformer (SST) is not recent, but with the use of advanced electronic switches and control strategies, the SST may soon become a practical reality. In this paper, conventional single-phase distribution transformers are replaced by solid-state transformers in a distribution test system to investigate their interactive dynamics. Under certain circumstances, instabilities due to harmonic resonance are observed. A design criterion for a solid-state transformer during no-load conditions has been proposed in order to avoid …

Efficient Integrity Verification Of Replicated Data In Cloud Using Homomorphic Encryption, Raghul Mukundan, Sanjay Madria, Mark Linderman

Computer Science Faculty Research & Creative Works

The cloud computing is an emerging model in which computing infrastructure resources are provided as a service over the internet. Data owners can outsource their data by remotely storing them in the cloud and enjoy on-demand high quality services from a shared pool of configurable computing resources. However, since data owners and the cloud servers are not in the same trusted domain, the outsourced data may be at risk as the cloud server may no longer be fully trusted. Therefore, data confidentiality, availability and integrity are of critical importance in such a scenario. The data owner encrypts data before storing …

Understanding Higher-Order Nonlocal Halo Bias At Large Scales By Combining The Power Spectrum With The Bispectrum, Shun Saito, Tobias Baldauf, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Understanding the relation between underlying matter distribution and biased tracers such as galaxies or dark matter halos is essential to extract cosmological information from ongoing or future galaxy redshift surveys. At sufficiently large scales such as the baryon acoustic oscillation (BAO) scale, a standard approach for the bias problem on the basis of the perturbation theory (PT) is to assume the "local bias" model in which the density field of biased tracers is deterministically expanded in terms of matter density field at the same position. The higher-order bias parameters are then determined by combining the power spectrum with higher-order statistics …

First All-Sky Search For Continuous Gravitational Waves From Unknown Sources In Binary Systems, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of Ω_GW(f) = Ω_{α …}