Digital Commons Network^™

Cardinal Raúl Silva Henríquez Bridge During The 2010 Chile Earthquake, Zuocai Wang, Genda Chen, W. Phillip Yen, Ian G. Buckle

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents a case study of the Cardinal Raúl Silva Henríquez Bridge, which experienced significant damage during an earthquake that occurred in Chile on February 27, 2010. Supported by reinforced concrete and steel columns of varying heights, the superstructure of the bridge consisted of 22 steel-girder spans, with one intermediate expansion joint located at the middle of the bridge. At each end of the bridge, the bottom flanges of the girders were welded to their bearing steel plates, which were embedded and anchored into the bridge abutment. Two, three-dimensional, finite element models (global versus local) with beam and solid …

Verification Of Information Flow Security In Cyber-Physical Systems, Rav Akella

Doctoral Dissertations

"With a growing number of real-world applications that are dependent on computation, securing the information space has become a challenge. The security of information in such applications is often jeopardized by software and hardware failures, intervention of human subjects such as attackers, incorrect design specification and implementation, other social and natural causes. Since these applications are very diverse, often cutting across disciplines a generic approach to detect and mitigate these issues is missing. This dissertation addresses the fundamental problem of verifying information security in a class of real world applications of computation, the Cyber-physical systems (CPSs). One of the motivations …

Detecting And Locating Electronic Devices Using Their Unintended Electromagnetic Emissions, Colin Stagner

Doctoral Dissertations

"Electronically-initiated explosives can have unintended electromagnetic emissions which propagate through walls and sealed containers. These emissions, if properly characterized, enable the prompt and accurate detection of explosive threats. The following dissertation develops and evaluates techniques for detecting and locating common electronic initiators. The unintended emissions of radio receivers and microcontrollers are analyzed. These emissions are low-power radio signals that result from the device's normal operation. In the first section, it is demonstrated that arbitrary signals can be injected into a radio receiver's unintended emissions using a relatively weak stimulation signal. This effect is called stimulated emissions. The performance of stimulated …

Numerical Modeling Of Heat Transfer And Fluid Flow In Laser Metal Deposition By Powder Injection, Zhiqiang Fan

Doctoral Dissertations

"Laser metal deposition is an additive manufacturing technique which allows quick fabrication of fully-dense metallic components directly from Computer Aided Design (CAD) solid models. A self-consistent three-dimensional model was developed for the laser metal deposition process by powder injection, which simulates heat transfer, phase changes, and fluid flow in the melt pool, The governing equations for solid, liquid and gas phases in the calculation domain have been formulated using the continuum model. The free surface in the melt pool has been tracked by the Volume of Fluid (VOF) method, while the VOF transport equation was solved using the Piecewise Linear …

Risk Analysis: Comparative Study Of Various Techniques, Hanan Mohammad Altabbakh

Doctoral Dissertations

"Researchers in the safety field are facing more challenges everyday with the expanding modern socio-technical systems. Safety analysis such as hazard analysis, accident causation analysis, and risk assessment are being revisited to overcome the shortcoming of the conventional safety analysis. With increasingly complex human system interaction in today's modern systems, new safety challenges are being faced that needed to be assessed and addressed. Managers and engineers face the challenge to choose from the vast amount of techniques available and utilize the correct one. Indeed, new or improved risk assessment tools that can address these complexities are needed. One of the …

Establishing Well Operability Limits For Frac Pack Sandface Well Completions Using A Screen Erosion Model And Well Completion Score Card, Rickey Hendrix

Doctoral Dissertations

"Completion quality has a direct impact upon the maximum production rate at which a frac pack well should be operated. Best practices for frac pack well completions ensure the highest possible quality for the well completion. A novel frac pack well completion score card was developed based on best practices for frac pack well completions identified through consultation with industry experts. The score card systematically combines and assesses completions data readily available standard completion reports. The outcome of the score card process is a numerical completion quality rating, which combines all well design and frac pack operations information.

The completion …

Development Of Marker-Based Human Motion Capture Systems For Assembly Simulation And Ergonomic Analysis, Sajeev C. Puthenveetil

Masters Theses

"In aerospace industry, the assembly operator is often exposed to potential ergonomic injuries due to awkward postures while working in confined spaces. Manually generating worker postures in simulation software for ergonomic analysis is cumbersome. This research focuses on the use of marker-based optical motion capture technology to generate human motion simulations in real-time for ergonomic analysis. To address the challenges involved in capturing human motions in a real work environment, an assembly operation was simulated in a four-walled Computer Automated Virtual Environment (CAVE) which provides an immersive 3D environment to the worker performing the assembly operation. Multiple cameras were set-up …

Some Insights For The Prediction Of Near-Wall Turbulence, Farid Karimpour, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this paper, we revisit the eddy viscosity formulation to highlight a number of important issues that have direct implications for the prediction of near-wall turbulence. For steady wall-bounded turbulent flows, we make the equilibrium assumption between rates of production (P) and dissipation (ε) of turbulent kinetic energy (κ) in the near-wall region to propose that the eddy viscosity should be given by vt ε/S², where S is the mean shear rate. We then argue that the appropriate velocity scale is given by (STL)-1/2 k^1/2 where TL = k ε is the turbulence (decay) time scale. The …

Use Of Vacuum For The Stabilization Of Dry Sand Slopes, B. Bate, Limin Zhang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Vacuum is proposed as a means for rescuing soil slopes showing signs of impending failure. Two aspects associated with the proposed method were studied: namely, the theory of airflow through dry soils and the effectiveness of vacuum for enhancing the stability of soil slopes. A model test device was developed, and two series of tests were carried out using this device. One was a series of tests on pore-air pressure distributions in dry sand slopes, and the second series involved dry sand slope stability tests. The results revealed that a vacuum (negative pore-air pressure) even as small as 20.4 kPa …

Effect Of Fly Ash On The Shear Strength Of Concrete Beams Without Shear Reinforcement, Mahdi Arezoumandi, Jeffery S. Volz, Carlos A. Ortega

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The following paper presents the results of an experimental investigation of the shear strength of full-scale reinforced concrete beams constructed with both high-volume fly ash concrete (HVFAC)-concrete with at least 50% of the cement replaced with fly ash-and conventional concrete (CC). This study includes two HVFAC mixes and one CC mix. The two HVFAC mixes are identical except for the amount of Class C fly ash replacement of cement, with one mix replacing 50% of the cement with fly ash and the other replacing 70 %. The test matrix included 18 beams-six for each concrete type-with three different longitudinal reinforcement …

Spacecraft Module Hole Size And Crack Length Prediction Following A Penetrating Debris Particle Impact, Joel E. Williamsen, William P. Schonberg, Hilary J. Evans

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The process used to calculate and reduce the consequences of meteoroid and orbital debris (MOD) penetrations and their link to catastrophic failure has evolved over time. As the threat of the orbital debris population increased in the 1980s and early 1990s, NASA developed a tool to determine the probability of no catastrophic failure, or PNCF, for the space station and to assess possible changes in station design and/or operations to improve that survivability percentage. PNCF is directly related to the PNP, or probability of no penetration, as calculated by Bumper, the code used by NASA to perform MOD risk assessments. …

Effect Of High-Volume Fly Ash On Shear Strength Of Concrete Beams, Mahdi Arezoumandi, Jeffery Volz, John Myers

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Every year concrete production exceeds 6.5 billion tons worldwide, nearly 1 ton for every man, woman, and child on the planet. In fact, concrete is used 10 times more than any other building material in the world, primarily because of its incredible versatility, availability, and relatively low cost. Unfortunately, the production of Portland cement - the key ingredient in concrete - generates approximately a pound of carbon dioxide for every pound of cement produced. One method of reducing concrete's carbon footprint is to replace a significant amount of the cement with fly ash, a by-product of coal-burning thermal power stations. …

Plants As Bio-Indicators Of Subsurface Conditions: Impact Of Groundwater Level On Btex Concentrations In Trees, Jordan Wilson, Rachel Bartz, Matt Limmer, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Numerous Studies Have Demonstrated Trees' Ability to Extract and Translocate Moderately Hydrophobic Contaminants, and Sampling Trees for Compounds Such as BTEX Can Help Delineate Plumes in the Field. However, When BTEX is Detected in the Groundwater, Detection in Nearby Trees is Not as Reliable an Indicator of Subsurface Contamination as Other Compounds Such as Chlorinated Solvents. Aerobic Rhizospheric and Bulk Soil Degradation is a Potential Explanation for the Observed Variability of BTEX in Trees as Compared to Groundwater Concentrations. the Goal of This Study Was to Determine the Effect of Groundwater Level on BTEX Concentrations in Tree Tissue. the Central …

Extending The Minimal Learning Machine For Pattern Classification, Amauri H.Souza Junior, Francesco Corona, Yoan Miche, Amaury Lendasse, Guilherme A. Barreto

Engineering Management and Systems Engineering Faculty Research & Creative Works

The Minimal Learning Machine (MLM) Has Been Recently Proposed as a Novel Supervised Learning Method for Regression Problems Aiming at Reconstructing the Mapping between Input and Output Distance Matrices. Estimation of the Response is Then Achieved from the Geometrical Configuration of the Output Points. Thanks to its Comprehensive Formulation, the MLM is Inherently Capable of Dealing with Nonlinear Problems and Multidimensional Output Spaces. in This Paper, We Introduce an Extension of the MLM to Classification Tasks, Thus Providing a Unified Framework for Mult response Regression and Classification Problems. on the Basis of Our Experiments, the MLM Achieves Results that Are …

Data Preprocessing And Model Design For Medicine Problems, Alberto Guillén, Amaury Lendasse, Guilherme Barreto

Engineering Management and Systems Engineering Faculty Research & Creative Works

No abstract provided.

Part I: Adaptive Systems Preface, David Enke

Engineering Management and Systems Engineering Faculty Research & Creative Works

No abstract provided.

A Fuzzy Evaluation Method For System Of Systems Meta-Architectures, Louis Pape, Kristin Giammarco, John Colombi, Cihan H. Dagli, Nil Kilicay-Ergin

Engineering Management and Systems Engineering Faculty Research & Creative Works

A method is proposed for evaluating a range of System of Systems (SoS) meta-architecture alternatives. SoS are composed through combination of existing, fully functioning Systems, possibly with minor functional changes, but certainly by using the combined Systems to achieve a new capability, not available from the Systems alone. The meta-architecture describes how all possible subsets of Systems can be combined to create an SoS. The fitness of a realizable SoS architecture may be characterized by terms such as unacceptable, marginal, above average, or excellent. While these terms provide little information about the SoS when used alone and informally, they readily …

How Many Antennas Does A Cooperative Jammer Need For Achieving The Degrees Of Freedom Of Multiple Antenna Gaussian Channels In The Presence Of An Eavesdropper?, Mohamed Nafea, Aylin Yener

Electrical and Computer Engineering Faculty Research & Creative Works

In this work, multiple antenna Gaussian wiretap channels with a multiantenna cooperative jammer are considered. In particular, the focus is on identifying the spatial resources needed at the cooperative jammer in order to achieve a secure degree of freedom (s.d.o.f.) for the channel in question equal to the degrees of freedom (d.o.f.). In order to accomplish this goal, the cooperative jammer sets out to send correlated jamming signals. Simultaneously, the legitimate transmitter chooses a precoder that perfectly aligns its information signals over the jamming ones at the eavesdropper. Both terminals use structured signaling, i.e., discrete constellations. The proposed approach is …

Tests For Time Domain Em Solvers For Stability And Towards Passivity, G. Antonini, Albert E. Ruehli, D. Romano, L. (Lijun) Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Stability issues for time domain integral equation based EM solvers have been a problem for a many years. In this paper, we consider ways to test for stability as well as other criteria towards passivity. The tests are designed to monitor the EM solver while the time domain solution is progressing. Hence, the solution can be terminated and improved with a passivization technique when a violation of the criterion has been detected. Also, the tests help to understand the cause of instabilities and results can be used for passivization. © 2013 IEEE.

Large-Scale Electromagnetic Computation For Modeling And Applications, Qing Huo Liu, Lijun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

The papers in this special issue are devoted to the topic of large-scale electromagnetic computation methods for modeling and applicatoins. © 1963-2012 IEEE.

A New Variable Step-Size Zero-Point Attracting Projection Algorithm, Jianming Liu, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a new variable step-size (VSS) scheme for the recently introduced zero-point attracting projection (ZAP) algorithm. The proposed variable step-size ZAPs are based on the gradient of the estimated filter coefficients' sparseness that is approximated by the difference between the sparseness measure of current filter coefficients and an averaged sparseness measure. Simulation results demonstrate that the proposed approach provides both faster convergence rate and better tracking ability than previous ones. © 2013 IEEE.

Low Complexity Soft-Interference Cancellation Turbo Equalization For Mimo Systems With Multilevel Modulations, Jingxian Wu, Longbao Wang, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a low complexity soft-interference cancellation equalizer (SICE) for the turbo detection of multiple-input multiple-output (MIMO) systems operating in time dispersive channels. The SICE contains three time-invariant linear filters: a feedforward filter, a causal feedback filter and an anti-causal feedback filter. The feedforward filter is designed to suppress the InterSymbol interference (ISI) due to time dispersive channels and the multiplexing interference from multiple transmit antennas. The causal (or anti-causal) feedback filter is developed to remove the residual interference caused by the symbols transmitted before (or after) the symbol under detection. The performance of the proposed SICE is verified …

Fpga Implementation Of Qr Decomposition For Mimo-Ofdm Using Four Cordic Cores, Bing Han, Zengli Yang, Yahong Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

A low-resource implementation of QR decomposition (QRD) is proposed for MIMO-OFDM systems that employ turbo MMSE-IC (Minimum mean square error interference cancellation) detector. The proposed implementation uses only four CORDIC cores for QR decomposition of complex-valued matrices while existing systolic array architecture requires 15 to 38 CORDIC cores to achieve similar throughput. For 4-by-4 MIMO with 1024 subcarrier OFDM, the turbo MMSE-IC requires 1024 QRD of 4-by-4 complex matrices followed by back substitution. Each matrix QRD is accompanied by rotations of four vectors for the second and subsequent turbo iterations. The proposed architecture implements the multiple vector rotation by multipliers …

Energy And Spectral Efficient Transmissions Of Coded Arq Systems, Jingxian Wu, Gang Wang, Yahong Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

Energy efficiency (EE) and spectral efficiency (SE) feature one of the most fundamental tradeoffs in communication systems. In this paper, we propose an optimum transmission scheme for coded Type-I automatic repeat request (ARQ) systems to balance the EE-SE tradeoff. The optimization is performed with respect to a new design metric, the normalized EE (NEE), which is defined as the energy per bit normalized by the SE. Minimizing NEE means either reducing the energy per bit or increasing the SE, it thus yields a balanced tradeoff between the two. The system design incorporates a wide range of practical system parameters, such …

Neural Network-Based Adaptive Event-Triggered Control Of Affine Nonlinear Discrete Time Systems With Unknown Internal Dynamics, Avimanyu Sahoo, Hao Xu, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the design of a neural network (NN) based adaptive model-based event-triggered control of an uncertain single input single output (SISO) nonlinear discrete time system in affine form is presented. The controller uses an adaptive estimator consisting of a single-layer NN not only to approximate the internal dynamics of an affine nonlinear discrete-time system but also to provide an estimate of the state vector during inter event interval. The NN weights of the adaptive NN estimator are tuned in a aperiodic manner at the event trigger instants unlike periodic updates in standard adaptive neural network (NN) control. A …

Adaptive Event-Triggered Control Of A Uncertain Linear Discrete Time System Using Measured Input And Output Data, Avimanyu Sahoo, Hao Xu, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, an adaptive model-based event-triggered control of an uncertain linear discrete time system is developed. Measured input and output vectors and their history are utilized to express the unknown linear discrete-time system as an autoregressive Markov representation (ARMarkov). A novel adaptive model in the form of AR Markov is proposed and an update law is derived in order to estimate parameters of the ARMarkov model at triggered instants unlike periodic updates in standard adaptive control. Lyapunov method is used to derive the event trigger condition, prove boundedness of the parameter vector and asymptotic convergence of the outputs and …

Neural Network-Based Optimal Control Of Mobile Robot Formations With Reduced Information Exchange, Travis Dierks, Bryan Brenner, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

A novel formation control scheme for mobile robots is introduced in the context of leader-follower framework with reduced communication exchange. The dynamical controller inputs for the robots are approximated from nonlinear optimal control techniques in order to track the designed control velocities generated by the kinematic controller. The proposed nonlinear optimal control technique, referred to as adaptive dynamic programming, uses neural networks (NNs) to solve the optimal formation control problem in discrete time in the presence of unknown internal dynamics and a known control coefficient matrix. A modification to the follower's kinematic controller is used to allow the desired formation …

Harmonic Distortion Optimization Of Cascaded H-Bridge Inverters Considering Device Voltage Drops And Noninteger Dc Voltage Ratios, Bill Diong, Hossein Sepahvand, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

This paper considers achieving the minimum total harmonic distortion (THD) or frequency-weighted THD (WTHD) of the staircase-modulated output voltage of single-phase multilevel inverters, with or without elimination of the lowest order harmonics. The minimal THD values, together with the corresponding step angles and dc voltage source ratios, have been obtained for the 5-, 7-, 9-, 11-, and 13-level cases; accounting for the device voltage drops when the load is resistive or is moderately inductive is described. Similarly, the minimal WTHD values, together with the corresponding step angles and dc source voltage ratios, have been obtained for the five-, seven-, and …

Resilience Experiments On The Gpeni Testbed, Egemen K. Çetinkaya, Dongsheng Zhang, Mohammed J. F. Alenazi, Yufei Cheng, Parker Riley, James P. G. Sterbenz

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

Reflection-Based Phase-Shifted Long Period Fiber Grating For Simultaneous Measurement Of Temperature And Refractive Index, Jie Huang, Xinwei Lan, Amardeep Kaur, Haining Wang, Lei Yuan, Hai Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

We report a reflection-based phase-shifted long period fiber grating (PS-LPFG) and demonstrate its capability for simultaneous measurement of temperature and external reflective index (RI). The sensor device comprises a grating directly written by CO₂ laser and silver-coated end face. A π-shifted LPFG is presented with two attenuation bands through its reflection spectrum. These two bands have different sensitivity towards temperature and external RI that can be used for simultaneous measurement of the two variables. The experimental results show that this probe-type PS-LPFG performs well in terms of linearity and sensitivity.