Digital Commons Network^™

Blackbox Macro-Modeling Of The Nonlinearity Based On Volterra Series Representation Of X-Parameters, Xiaoyan Y.Z. Xiong, Li (Lijun) J. Jiang, José E. Schutt-Ainé, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

Volterra series representation is a powerful mathematical model for nonlinear devices. However, the difficulties in determining higher-order Volterra kernels limited its broader applications. This paper proposed a systematic approach that enables a convenient extraction of Volterra kernels from X-parameters for the first time. Then the Vandermonde method is employed to separate different orders of Volterra kernels at the same frequency, which leads to a highly efficient extraction process. The proposed Volterra series representation based on X-parameters is further benchmarked for verification. The proposed new algorithm is very useful for the blackbox macro-modeling of nonlinear devices and systems.

A Calderón Preconditioner For The Electric Field Integral Equation With Layered Medium Green's Function, Yongpin P. Chen, Sheng Sun, Lijun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A Calderón preconditioner is developed for the analysis of electromagnetic scattering of perfect electrically conducting (PEC) objects embedded in a layered medium. The electric field integral equation (EFIE) is formulated with the kernel of layered medium Green's function to account for the effects from the multilayered background. The Calderón projector is derived based on the general source-field relationship and the extinction theorem for inhomogeneous environment in electromagnetic theory. The Calderón identities can be naturally deduced based on this projector, which is then leveraged to precondition the EFIE with layered kernel. An alternative implementation is then proposed to make the implementation …

Helmholtz Decomposition Based On Integral Equation Method For Electromagnetic Analysis, Xiaoyan Y.Z. Xiong, Wei E.I. Sha, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Helmholtz decomposition (HD) is a vector analysis fundamental tool and plays an important role in electromagnetics (EM) and microwave engineering. Instead of applying HD to the EM solving process, this article proposes an integral equation based rigorous HD process to extract and analyze the known EM field. It provides much clearer insight into field coupling and radiation mechanism that is valuable to electromagnetic interference (EMI) and electromagnetic compatibility (EMC) analysis. Compared to the loop-tree based decomposition that is a quasi-HD, the proposed method is rigorous and frequency-independent. The algorithm verification and its application to coupling and resonating problems are presented. …

A Hybrid Time-Domain Discontinuous Galerkin-Boundary Integral Method For Electromagnetic Scattering Analysis, Ping Li, Yifei Shi, Li (Lijun) Jun Jiang, Hakan Baǧci

Electrical and Computer Engineering Faculty Research & Creative Works

A scheme hybridizing discontinuous Galerkin time-domain (DGTD) and time-domain boundary integral (TDBI) methods for accurately analyzing transient electromagnetic scattering is proposed. Radiation condition is enforced using the numerical flux on the truncation boundary. The fields required by the flux are computed using the TDBI from equivalent currents introduced on a Huygens' surface enclosing the scatterer. The hybrid DGTDBI ensures that the radiation condition is mathematically exact and the resulting computation domain is as small as possible since the truncation boundary conforms to scatterer's shape and is located very close to its surface. Locally truncated domains can also be defined around …

Verifiable Frequency-Limited Adaptive Control Performance Based On Linear Matrix Inequalities, Mario Luca Fravolini, Tansel Yucelen, Daniel Wagner, Ali Albattat, Paolo Valigi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Adaptive controllers are often criticized for the lack of clear and easy verification procedures that relate design parameters to time domain performance especially during transients. For this reason, it is a challenge to rigorously certify existing adaptive control algorithms. To that end, we propose a validation framework where stability and performance requirements are formulated in terms of Linear Matrix Inequalities. This brings the advantage that adaptive controller design and verification can be analyzed and optimized via the solution of a convex optimization whose objective is to guarantee the evolution of the error components within an a-priori specified domain. This approach …

A Kalman Filter With Individual Control Factors For Echo Cancellation, Constantin Paleologu, Jacob Benesty, Silviu Ciochinǎ, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

In echo cancellation, the main goal is to recover the near-end signal from the error signal of the adaptive filter, which identifies the echo path. In this context, the Kalman filter represents a very appealing choice, since its basic criterion follows the minimization of the system misalignment (instead of the usual error-based cost function). In this paper, we propose a Kalman filter with individual control factors, in terms of using a different level of uncertainty for each coefficient of the filter. As compared to the basic Kalman filter (which imposes the same uncertainty for all the coefficients of the impulse …

Localization And Tracking Of Objects Using Cross-Correlation Of Shadow Fading Noise, M. R. Basheer, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

Multipath and shadow fading are the primary cause for positioning errors in a Received Signal Strength Indicator (RSSI) based localization scheme. While fading, in general, is detrimental to localization accuracy, cross-correlation and divergence properties of shadow fading residuals may be utilized to improve localization and tracking accuracy of mobile IEEE 802.15.4 transmitters. Therefore, this paper begins by presenting a stochastic filter that models the fast-changing multipath fading as a mean reverting Ornstein-Uhlenbeck (OU) process followed by a Generalized Auto Regressive Conditional Heteroskedasticity (GARCH) filtering to isolate the slow changing shadow fading residuals from measured RSSI values. Subsequently, a novel wireless …

A Fault Prediction Scheme For Takagi-Sugeno Fuzzy Systems With Immeasurable Premise Variables And Disturbance, Balaje T. Thumati, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

As explained in the literature, it is very hard to measure premise variables of a Takagi-Sugeno (TS) fuzzy system. Therefore, in this paper, a fault detection and prediction (FDP) scheme is designed for a class of TS fuzzy systems with immeasurable (unknown) premise variables and external disturbances. A fault detection (FD) observer is designed to approximate the system output and the premise variables. Subsequently, a FD residual is generated by comparing the observer output with respect to the system output. The FD residual is evaluated to detect any faults in the system. Further, time-to-failure (TTF) of the TS fuzzy system …

Extremum-Seeking For Nonlinear Discrete-Time Systems With Application To Hcci Engines, H. Zargarzadeh, S. Jagannathan, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

For many control applications, identifying an optimal operating point by maximizing/minimizing a performance function is important. This paper applies the extremum-seeking method to nonaffine, nonlinear discrete-time systems stabilized by an optimal adaptive controller. First, a novel averaging method is used for the nonlinear discrete-time systems to show that their output unique extrema are stable equilibrium points. Then, a singular perturbation method in discrete time is employed to show that the overall closed loop system will dynamically converge to the extremum. The applicability of this scheme is numerically verified on a Homogeneous Charge Compression Ignition (HCCI) model validated experimentally and expressed …

Optimization Of Transmission Conditions In Waveform Relaxation Techniques For Rc Circuits, Mohammad D. Al-Khaleel, Martin J. Gander, Albert E. Ruehli

Electrical and Computer Engineering Faculty Research & Creative Works

Waveform relaxation techniques have become increasingly important with the wide availability of parallel computers with a large number of processors. A limiting factor for classical waveform relaxation, however, is the convergence speed for an important class of problems, especially if long time windows are considered. In contrast, the optimized waveform relaxation algorithm discussed in this paper is well suited to address this problem. Today several numerical analyses have shown that optimized waveform relaxation algorithms can overcome slow convergence over long time windows. However, the optimized waveform relaxation techniques require the determination of optimized parameters. In this paper, we present a …

Adaptive Control Of Uncertain Systems With Gain Scheduled Reference Models, Mehrdad Pakmehr, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper develops a new model reference adaptive control approach for uncertain systems with gain scheduled reference models in a multi-input multi-output (MIMO) setting. Specifically, adaptive state feedback for output tracking control problem of MIMO nonlinear systems is studied and gain scheduled reference model system is used for generating desired state trajectories. Using convex optimization tools, a single Lyapunov matrix is computed for multiple linearization's near equilibrium and non-equilibrium points of the nonlinear closed loop gain scheduled reference system. This approach guarantees stability of the closed loop gain scheduled system. Adaptive state feedback control scheme is then developed, and its …

Approximate Dynamic Programming, Local Or Global Optimal Solution?, Ali Heydari, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of global optimality analysis of approximate dynamic programming-based solutions is investigated in this study. Sufficient conditions for global optimality are obtained without requiring the state penalizing terms in the cost function or the functions representing the dynamics to be convex functions. Afterwards, the theoretical results are confirmed through a qualitative analysis of an example problem. © 2014 American Automatic Control Council.

Optimal Switching Of Nonlinear Systems With Free Mode Sequence, Ali Heydari, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Approximate dynamic programming is utilized in this study to develop solutions for optimal switching problems. The order of the active subsystems and the number of switches are free, and an online solution is developed that produces optimal performance. Motivated by the development in the adaptive critic's literature, the proposed method uses a critic and as many actors as the number of subsystems in order to conduct optimal scheduling in real-time based on the instantaneous states of the system. It is observed that once the neural networks are trained offline based on the proposed algorithm, they provide solutions for a range …

Fixed Final-Time Near Optimal Regulation Of Nonlinear Discrete-Time Systems In Affine Form Using Output Feedback, Qiming Zhao, Hao Xu, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the fixed final-time near optimal output regulation of affine nonlinear discrete-time systems with unknown system dynamics is considered. First, a neural network (NN)-based observer is proposed to reconstruct both the system state vector and control coefficient matrix. Next, actor-critic structure is utilized to approximate the time-varying solution of the Hamilton-Jacobi-Bellman (HJB) equation or value function. To satisfy the terminal constraint, a new error term is defined and incorporated in the NN update law so that the terminal constraint error is also minimized over time. A NN with constant weights and time-dependent activation function is employed to approximate …

An Online Outlier Identification And Removal Scheme For Improving Fault Detection Performance, Hasan Ferdowsi, Sarangapani Jagannathan, Maciej Jan Zawodniok

Electrical and Computer Engineering Faculty Research & Creative Works

Measured data or states for a nonlinear dynamic system is usually contaminated by outliers. Identifying and removing outliers will make the data (or system states) more trustworthy and reliable since outliers in the measured data (or states) can cause missed or false alarms during fault diagnosis. In addition, faults can make the system states nonstationary needing a novel analytical model-based fault detection (FD) framework. In this paper, an online outlier identification and removal (OIR) scheme is proposed for a nonlinear dynamic system. Since the dynamics of the system can experience unknown changes due to faults, traditional observer-based techniques cannot be …

Proper Orthogonal Decomposition Technique For Sub-Optimal Control Of Flexible Aircraft Wings Using Discrete Actuators, M. Kumar, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Distributed parameter systems are, generally, described by a set of partial differential equations. Control design of these systems is a very complex task as compared to that of the lumped parameter systems that are defined by a set of ordinary differential equations. In this paper, we present a stabilizing state-feedback control design approach for a class of second order system, where the system can be controlled by discrete actuators in the spatial domain. The control methodology is developed by combining the technique of 'Proper Orthogonal Decomposition' and Approximate Dynamic Programming. The Proper Orthogonal Decomposition technique is utilized to obtain a …

Adaptive Neural Network-Based Optimal Control Of Nonlinear Continuous-Time Systems In Strict-Feedback Form, H. Zargarzadeh, T. Dierks, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper focuses on neural network (NN) based optimal control of nonlinear continuous-time systems in strict-feedback form when the system dynamics are known by using an adaptive backstepping approach. A single NN-based adaptive approach is designed to learn the solution of the infinite horizon continuous-time Hamilton-Jacobi-Bellman (HJB) equation while the corresponding optimal control input that minimizes the HJB equation is calculated in a forward-in-time manner without using value and policy iterations. First, the optimal control problem is solved for a generic multi-input and multi-output nonlinear system with a state feedback approach. Then the approach is extended to a single-input and …

Neural Network-Based Finite-Horizon Approximately Optimal Control Of Uncertain Affine Nonlinear Continuous-Time Systems, Hao Xu, Qiming Zhao, Travis Dierks, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper develops a novel neural network (NN) based finite-horizon approximate optimal control of nonlinear continuous-time systems in affine form when the system dynamics are complete unknown. First an online NN identifier is proposed to learn the dynamics of the nonlinear continuous-time system. Subsequently, a second NN is utilized to learn the time-varying solution, or referred to as value function, of the Hamilton-Jacobi-Bellman (HJB) equation in an online and forward in time manner. Then, by using the estimated time-varying value function from the second NN and control coefficient matrix from the NN identifier, an approximate optimal control input is computed. …

Combustion Visualization And Particulate Matter Emission Of A Gdi Engine By Using Gasoline And E85, Po-I Lee

Wayne State University Dissertations

In order to increase engine efficiency as well as to reduce emission, optimizing combustion is always the challenge in research and product development. Gasoline direct injection (GDI) engines have been popularized due to its higher power density, fuel efficiency, and the possibility for advanced engine technologies over conventional port-fuel-injection (PFI) gasoline engines. However, many issues are heavily investigated, such as air-fuel mixing preparation, fuel wall-wetting, higher HC and PM emissions, catalytic convertor efficiency, knocking, and pre-ignition. Besides, advanced technologies represent higher production cost.

Because of the limited resource of petroleum-based fuels, ethanol is deemed as the alternative fuel for gasoline …

Weak Decay Studies From An Effective Theory Standpoint, Aditya Yechan Gunja

Wayne State University Dissertations

In this doctoral dissertation I discuss the phenomenology of some weak interaction decays using a model independent approach by employing effective field theories. I discuss the soft photon contribution and background effect to the rare dimuonic decay of the neutral B meson. I also study some radiative exclusive W boson decays in the standard model in the context of pQCD and SCET. Additionally I invoke leptonic decays of charged mesons to constrain two general models of light dark matter.

Coupled Sediment Yield And Sediment Transport Model To Support Navigation Planning In Northeast Brazil, Calvin Trebor Creech

Wayne State University Dissertations

Deposition of sediment (shoaling) in commercial waterways is a major obstacle to maintaining sustainable riverine transportation of bulk goods (primarily agricultural and mining commodities). The rate of aggradation of sediment in a waterway is directly related to both the rate of sediment erosion from upland and river bank sources (sediment yield) and the energy in the river to effectively transport the sediment through the waterway system (sediment transport). Historically, methods used for waterway development have included trial and error or rules of thumb associated with river training structures and chute cut-off canals or engineering of navigation locks and dams. More …

Theoretical And Experimental Studies Of Noncovalent Metal Cation Binding And Base Pairing Interactions Of Cytosine And Modified Cytosines, Bo Yang

Wayne State University Dissertations

ABSTRACT

THEORETICAL AND EXPERIMENTAL STUDIES OF NONCOVALENT METAL CATION BINDING AND BASE PARING INTERACTIONS OF CYTOSINE AND MODIFIED CYTOSINES

by

BO YANG

December 2014

Advisor: Professor Mary T. Rodgers

Major: Analytical Chemistry

Degree: Doctor of Philosophy

Binding of metal cations to the nucleobases can lead to formation of rare tautomers of the nucleobases. The infrared multiple photon dissociation (IRMPD) action spectroscopy of five alkali metal cation-cytosine complexes, M⁺(cytosine), where M⁺ = Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺, are examined using a Fourier transform ion cyclotron resonance mass …

Synthesis And Characterization Of Discrete Fexni2-Xp Nanoparticles; Assembly Of Phosphide Nanoparticles Into Porous Networks, Asha Hitihami Mudiyanselage

Wayne State University Dissertations

This dissertation research is focused on synthesis, characterization and assembly of metal phosphide nanoparticles of relevance to catalysis, magnetism, and optoelectronic applications. These include (1) synthesis of discrete FexNi2-xP ternary nanocrystals of relevance to hydrodesulfurization (HDS) catalysis and magnetism, and (2) 3-dimensional nanostructures (gels and aerogels) of InP and Ni2P.

A three-step solution-phase arrested precipitation method was employed for bimetallic nanocrystal synthesis. The synthesis of nanocrystals involves preparation of amorphous NixPy amorphous particles, introduction of the Fe precursor to form amorphous Fe-Ni-P particles, and high temperature conversion of Fe-Ni-P particles into crystalline ternary phosphide nanocrystals. Ternary FexNi2-xP nanocrystals crystalize in …

Analysis Of A Dual Scissored-Pair,Variable-Speed, Control Moment Gyroscope Driven Spherical Robot, Richard Chase

Wayne State University Dissertations

The objective of this research is to compare barycenter offset based designs of spherical robots to control moment gyroscope (CMG) based designs in order to determine which approach is most effective. The first objective was to develop a list of current state of the art designs in order to gain an overall understanding of what the obstacles in this area of research were. The investigation showed that barycenter offset designs can produce a low, continuous output torque, whereas CMG based designs can usually only produce a high, momentary output torque. The second objective was to develop a CMG based design …

Inclusive Education For Students With Emotional Impairments: Factors For Success, Jessica Cohen

Wayne State University Dissertations

Special education policy and practice are ever evolving to best meet the needs of all students in an inclusive environment. Since the implementation the Individuals with Disabilities Education Act (IDEA) thirty years ago, students with special needs have moved from restrictive, exclusionary placements to being educated alongside their same aged non-disabled peers. As we have moved towards viewing special education as a service, not a place, including more students with disabilities in the general education setting and curriculum has become the expected practice in the majority of public schools in the United States. Despite this progress, students with emotional impairments …

The Role Of Academic Factors, Self-Efficacy, Mentoring Relationships, And Learning Communities In Persistance And Academic Success Of Freshmen College Students, Stefanie Theresia Baier

Wayne State University Dissertations

Many U.S. universities are concerned with student retention. The current study surveyed 237 first time college students at a Midwestern university to determine the extent to which social-cognitive factors, such as high school GPA, ACT scores, first semester college GPA, college self-efficacy and perceptions of mentorship support influence freshmen's intent to persist and academic success.

Pearson Correlations, Standard Multiple Regression Analyses, PROCESS for Mediation and Moderation, and a MANOVA were performed. The study's findings show that college self-efficacy and perceptions of mentorship were the strongest predictors for intentions to persist past the first college semester. High school GPA was the …

Nanostrucured Lithium Iron Phosphate As Cathode Material For Lithium Ion-Batteries, Khadije Bazzi

Wayne State University Dissertations

Lithium-ion batteries are the power source of choice for portable electronics, power tools and electric-based transportation. This outstanding commercial success has spawned great international interest in applying this technology to systems that demand higher power, such as the electric component of hybrid, extended range, and electric vehicles. This would require new electrode materials that are less expensive, more energetic, and more environmentally friendly than the present ones. Of particular interest is the olivine-structured LiFePO4 cathode developed by Goodenough and co-workers, which offers several appealing features, such as a high, flat voltage profile and relatively high theoretical specific capacity (170 mAhg−1), …

Text Extraction In Natural Scenes Using Region-Based Method, Zhihu Huang, Jinsong Leng

Research outputs 2014 to 2021

Text in images is a very important clue for image indexing and retrieving. Unfortunately, it is a challenging work to accurately and robustly extract text from a complex background image. In this paper, a novel region-based text extraction method is proposed. In doing so, the candidate text regions are detected by 8-connected objects detection algorithm based on the edge image. Then the non-text regions are filtered out using shape, texture and stroke width rules. Finally, the remaining regions are grouped into text lines. Since stroke width is the intrinsic and particular characteristics of the text, the accuracy of the non-text …

A Master's Recital In Piano, Min Jeong Kim

Dissertations and Theses @ UNI

On March 14, 2014, Min Jeong Kim presented a recital in completion of her Master’s degree in Piano Performance. The recital was held at 6 p.m. in Davis Hall at the University of Northern Iowa School of Music. Pieces on the program included: Prelude and Fugue in C minor, BWV 871 by Johann Sebastian Bach, Klavierstücke, Op. 118 by Johannes Brahms, Rain Tree Sketch II by Toru Takemitsu, and Sonata in E-flat Major, Op. 81a by Ludwig van Beethoven.

Ru/C: A Simple Heterogeneous Catalyst For The Amination Of Azoles Under Ligand Free Conditions, K. Harsha Vardhan Reddy, B. S.P. Anil Kumar, V. Prakash Reddy, R. Uday Kumar, Y. V.D. Nageswar

Chemistry Faculty Research & Creative Works

A ligand free Ru/C-catalyzed amination of 2-halo azoles with a broad scope of aminating reagents has been developed. A variety of 2-aminoazole derivatives were synthesized in moderate to good yields by utilizing this protocol. The methodology is operationally simple and not sensitive to air and moisture. It provides potentially useful products by using an inexpensive and recyclable catalytic system under ligand free conditions without significant loss of its catalytic activity up to four cycles. This journal is