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Full-Text Articles in Engineering
A Three-Dimensional Fdtd Subgridding Algorithm With Separated Temporal And Spatial Interfaces And Related Stability Analysis, Kai Xiao, David Pommerenke, James L. Drewniak
A Three-Dimensional Fdtd Subgridding Algorithm With Separated Temporal And Spatial Interfaces And Related Stability Analysis, Kai Xiao, David Pommerenke, James L. Drewniak
Electrical and Computer Engineering Faculty Research & Creative Works
A finite-different time-domain subgrid algorithm locally refines the mesh at regions requiring higher resolution. A novel separation of spatial and temporal subgridding interfaces is presented that allows implementing a novel spatial subgridding method and investigating the stability of each subalgorithm individually. Details are given for a spatial subgridding algorithm having a 1:3 mesh ratio. In the spatial subgridding algorithm, the fine-mesh is constructed with a recessed interface and the interpolation scheme is designed to be symmetric to maintain the stability of the update process. The stability of the spatial subgridding algorithm is analyzed with a matrix method. Numerical examples showing …
Nanomanipulation Using Atomic Force Microscope With Drift Compensation, Qinmin Yang, Jagannathan Sarangapani
Nanomanipulation Using Atomic Force Microscope With Drift Compensation, Qinmin Yang, Jagannathan Sarangapani
Electrical and Computer Engineering Faculty Research & Creative Works
This paper proposes an atomic force microscope (AFM) based force controller to push nanoparticles on the substrates since it is tedious for human. A block phase correlation-based algorithm is embedded into the controller for compensating the thermal drift during nanomanipulation. Further, a neural network (NN) is employed to approximate the unknown nanoparticle and substrate contact dynamics including the roughness effects. Using the NN-based adaptive force controller the task of pushing nanoparticles is demonstrated. Finally, using the Lyapunov-based stability analysis, the uniform ultimately boundedness (UUB) of the closed-loop signals is demonstrated
Neural Network-Based Output Feedback Controller For Lean Operation Of Spark Ignition Engines, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier, Jonathan B. Vance, Pingan He
Neural Network-Based Output Feedback Controller For Lean Operation Of Spark Ignition Engines, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier, Jonathan B. Vance, Pingan He
Electrical and Computer Engineering Faculty Research & Creative Works
Spark ignition (SI) engines running at very lean conditions demonstrate significant nonlinear behavior by exhibiting cycle-to-cycle dispersion of heat release even though such operation can significantly reduce NOx emissions and improve fuel efficiency by as much as 5-10%. A suite of neural network (NN) controller without and with reinforcement learning employing output feedback has shown ability to reduce the nonlinear cyclic dispersion observed under lean operating conditions. The neural network controllers consists of three NN: a) A NN observer to estimate the states of the engine such as total fuel and air; b) a second NN for generating virtual input; …
A Three-Dimensional Fdtd Subgridding Method With Separate Spatial And Temporal Subgridding Interfaces, Kai Xiao, David Pommerenke, James L. Drewniak
A Three-Dimensional Fdtd Subgridding Method With Separate Spatial And Temporal Subgridding Interfaces, Kai Xiao, David Pommerenke, James L. Drewniak
Electrical and Computer Engineering Faculty Research & Creative Works
The idea of separating the spatial and temporal subgridding interfaces is introduced in this paper. Based on this idea, the spatial and temporal subgridding algorithms can be developed and analyzed separately. The spatial algorithm was given in the previous paper. In this paper, the temporal subgridding algorithm is described and the stability is illustrated by the analytical formulation of a one-dimensional model. An FDTD code that combines the spatial and temporal subgridding algorithms is implemented. Numerical test models are calculated to show the stability and accuracy of the proposed method.
Coordination Of Ufls And Ufgc By Application Of D-Smes, Li Zhang, Yilu Liu, Mariesa Crow
Coordination Of Ufls And Ufgc By Application Of D-Smes, Li Zhang, Yilu Liu, Mariesa Crow
Electrical and Computer Engineering Faculty Research & Creative Works
In this paper, the authors studied the coordination of under frequency load shedding (UFLS) and under frequency governor control (UFGC) by applying the distributed superconducting magnetic energy storage (D-SMES) devices. The active power of D-SMES device is controlled to eliminate the initial rapid frequency drop and allow time for the full action of UFGC to take over. The reactive power of D-SMES is controlled to stabilise the local bus voltage. The research results show that D-SMES devices can damp the quick dropping of system frequency and hold it waiting for the full activation of system spinning reserve. D-SMES can help …
Pulse Regulation Control Technique For Integrated High-Quality Rectifier-Regulators, Mehdi Ferdowsi, Ali Emadi
Pulse Regulation Control Technique For Integrated High-Quality Rectifier-Regulators, Mehdi Ferdowsi, Ali Emadi
Electrical and Computer Engineering Faculty Research & Creative Works
The pulse regulation control scheme is presented and applied to the boost integrated flyback rectifier/energy storage dc/dc (BIFRED) converter as the most popular member of the integrated high-quality rectifier-regulators (IHQRR). In contrast to the conventional control techniques, the principal idea of pulse regulation is to regulate the output voltage using a series of high- and low-power pulses generated by the current of the input inductor, which is operating in discontinuous conduction mode (DCM). Analysis of the BIFRED converter operating in DCM is presented. Fundamentals of pulse regulation as well as its stability analysis and the estimation of the output voltage …
Low-Input-Voltage, Low-Power Boost Converter Design Issues, Jonathan W. Kimball, Theresa L. Flowers, Patrick L. Chapman
Low-Input-Voltage, Low-Power Boost Converter Design Issues, Jonathan W. Kimball, Theresa L. Flowers, Patrick L. Chapman
Electrical and Computer Engineering Faculty Research & Creative Works
Issues associated with boost converter design and performance are investigated when a low input voltage is used. Low-input-voltage sources include single fuel cells, single solar cells, and thermoelectric devices. The primary context is interfacing single micro fuel cells to portable electronic loads, such as mobile phones. Efficiency and circuit startup are the two most difficult issues for a low-cost design. It is shown in theory and experiment that the boost converter has a voltage collapse point. A simple startup technique is proposed that is appropriate for some applications.
A Three-Dimensional Fdtd Subgridding Algorithm Based On Interpolation Of Current Density, Kai Xiao, David Pommerenke, James L. Drewniak
A Three-Dimensional Fdtd Subgridding Algorithm Based On Interpolation Of Current Density, Kai Xiao, David Pommerenke, James L. Drewniak
Electrical and Computer Engineering Faculty Research & Creative Works
A three-dimensional subgridding algorithm for the finite difference time domain (FDTD) method is proposed in this paper. The method is based on interpolation of electric and magnetic current densities. The coarse-fine mesh ratio can be either 1:2 or 1:3. Results of a test model utilizing a lossless cavity excited with a dipole show no tendency of instability after 500000 time steps. The reflection in time domain at the subgridding interface was calculated to test the accuracy of the subgridding algorithm.
Measuring The Robustness Of A Resource Allocation, Shoukat Ali, A. A. Maciejewski, Howard Jay Siegel, Jong-Kook Kim
Measuring The Robustness Of A Resource Allocation, Shoukat Ali, A. A. Maciejewski, Howard Jay Siegel, Jong-Kook Kim
Electrical and Computer Engineering Faculty Research & Creative Works
Parallel and distributed systems may operate in an environment that undergoes unpredictable changes causing certain system performance features to degrade. Such systems need robustness to guarantee limited degradation despite fluctuations in the behavior of its component parts or environment. This research investigates the robustness of an allocation of resources to tasks in parallel and distributed systems. The main contributions are 1) a mathematical description of a metric for the robustness of a resource allocation with respect to desired system performance features against multiple perturbations in multiple system and environmental conditions, and 2) a procedure for deriving a robustness metric for …
The Robustness Of Resource Allocation In Parallel And Distributed Computing Systems, Shoukat Ali, Howard Jay Siegel, A. A. Maciejewski
The Robustness Of Resource Allocation In Parallel And Distributed Computing Systems, Shoukat Ali, Howard Jay Siegel, A. A. Maciejewski
Electrical and Computer Engineering Faculty Research & Creative Works
This paper gives an overview of the material to be discussed in the invited keynote presentation by H. J. Siegel. Performing computing and communication tasks on parallel and distributed systems involves the coordinated use of different types of machines, networks, interfaces, and other resources. Decisions about how best to allocate resources are often based on estimated values of task and system parameters, due to uncertainties in the system environment. An important research problem is the development of resource management strategies that can guarantee a particular system performance given such uncertainties. We have designed a methodology for deriving the degree of …
A Continually Online Trained Neurocontroller For The Series Branch Control Of The Upfc, Ganesh K. Venayagamoorthy, Radha P. Kalyani
A Continually Online Trained Neurocontroller For The Series Branch Control Of The Upfc, Ganesh K. Venayagamoorthy, Radha P. Kalyani
Electrical and Computer Engineering Faculty Research & Creative Works
The crucial factor affecting the modern power systems today is load flow control. The Unified Power Flow Controller (UPFC) provides an effective means for controlling the power flow and improving the transient stability in a power network. The UPFC has fast complex dynamics and its conventional control is based on a linearized model of the power system. This paper presents the design of a neurocontroller that controls the power flow and regulates voltage along a transmission line. The continually online neurocontroller is used for controlling the series inverter of UPFC. Simulation results carried out in the PSCAD/EMTDC environment are presented …
Neuro Emission Controller For Minimizing Cyclic Dispersion In Spark Ignition Engines, Pingan He, Jagannathan Sarangapani
Neuro Emission Controller For Minimizing Cyclic Dispersion In Spark Ignition Engines, Pingan He, Jagannathan Sarangapani
Electrical and Computer Engineering Faculty Research & Creative Works
A novel neural network (NN) controller is developed to control spark ignition (SI) engines at extreme lean conditions. The purpose of neurocontroller is to reduce the cyclic dispersion at lean operation even when the engine dynamics are unknown. The stability analysis of the closed-loop control system is given and the boundedness of all signals is ensured. Results demonstrate that the cyclic dispersion is reduced significantly using the proposed controller. The neuro controller can also be extended to minimize engine emissions with high EGR levels, where similar complex cyclic dynamics are observed. Further, the proposed approach can be applied to control …
Intelligent Control Of Turbogenerator Exciter/Turbine On The Electric Power Grid To Improve Power Generation And Stability, Ganesh K. Venayagamoorthy, Ronald G. Harley, Donald C. Wunsch
Intelligent Control Of Turbogenerator Exciter/Turbine On The Electric Power Grid To Improve Power Generation And Stability, Ganesh K. Venayagamoorthy, Ronald G. Harley, Donald C. Wunsch
Electrical and Computer Engineering Faculty Research & Creative Works
A review of the applications of intelligent control to replace/augment the conventional excitation and/or turbine control of turbogenerators on the electric power grid is presented in the paper. The intelligent controller designs are based on neural networks and adaptive critic designs (ACDs). The feedback variables are completely based on local measurements from the generators. Simulations and some practical laboratory implementations on a single-machine-infinite-bus and a three-machine power system demonstrate that intelligent controllers are much more effective than the conventional PID control for improving dynamic performance and stability of the power grid under small and large disturbances. The safety margins on …
Counterexample Of A Claim Pertaining To The Synthesis Of A Recurrent Neural Network, Xindi Cai, Donald C. Wunsch
Counterexample Of A Claim Pertaining To The Synthesis Of A Recurrent Neural Network, Xindi Cai, Donald C. Wunsch
Electrical and Computer Engineering Faculty Research & Creative Works
Recurrent neural networks have received much attention due to their nonlinear dynamic behavior. One such type of dynamic behavior is that of setting a fixed stable state. This paper shows a counterexample to the claim of A.N. Michel et al. (IEEE Control Systems Magazine, vol. 15, pp. 52-65, Jun. 1995), that "sparse constraints on the interconnecting structure for a given neural network are usually expressed as constraints which require that pre-determined elements of T [a real n×n matrix acting on a real n-vector valued function] be zero", for the synthesis of sparsely interconnected recurrent neural networks.
Comparison Of Heuristic Dynamic Programming And Dual Heuristic Programming Adaptive Critics For Neurocontrol Of A Turbogenerator, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley
Comparison Of Heuristic Dynamic Programming And Dual Heuristic Programming Adaptive Critics For Neurocontrol Of A Turbogenerator, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley
Electrical and Computer Engineering Faculty Research & Creative Works
This paper presents the design of an optimal neurocontroller that replaces the conventional automatic voltage regulator (AVR) and the turbine governor for a turbogenerator connected to the power grid. The neurocontroller design uses a novel technique based on the adaptive critic designs (ACDs), specifically on heuristic dynamic programming (HDP) and dual heuristic programming (DHP). Results show that both neurocontrollers are robust, but that DHP outperforms HDP or conventional controllers, especially when the system conditions and configuration change. This paper also shows how to design optimal neurocontrollers for nonlinear systems, such as turbogenerators, without having to do continually online training of …
Excitation And Turbine Neurocontrol With Derivative Adaptive Critics Of Multiple Generators On The Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley
Excitation And Turbine Neurocontrol With Derivative Adaptive Critics Of Multiple Generators On The Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley
Electrical and Computer Engineering Faculty Research & Creative Works
Based on derivative adaptive critics, neurocontrollers for excitation and turbine control of multiple generators on the electric power grid are presented. The feedback variables are completely based on local measurements. Simulations on a three-machine power system demonstrate that the neurocontrollers are much more effective than conventional PID controllers, the automatic voltage regulators and the governors, for improving the dynamic performance and stability under small and large disturbances
Dc Link Stabilized Field Oriented Control Of Electric Propulsion Systems, Keith Corzine, S. D. Sudhoff, Steven F. Glover, H. J. Hegner, H. N. Robey
Dc Link Stabilized Field Oriented Control Of Electric Propulsion Systems, Keith Corzine, S. D. Sudhoff, Steven F. Glover, H. J. Hegner, H. N. Robey
Electrical and Computer Engineering Faculty Research & Creative Works
Induction motor based electric propulsion systems can be used in a wide variety of applications including locomotives, hybrid electric vehicles, and ships. Field oriented control of these drives is attractive since it allows the torque to be tightly and nearly instantaneously controlled. However, such systems can be prone to negative impedance instability of the DC link. This paper examines this type of instability and sets forth a readily implemented albeit nonlinear control strategy to mitigate this potential problem.
A Practical Continually Online Trained Artificial Neural Network Controller For A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley
A Practical Continually Online Trained Artificial Neural Network Controller For A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley
Electrical and Computer Engineering Faculty Research & Creative Works
This paper reports on the simulation and practical studies carried out on a single turbogenerator connected to an infinite bus through a short transmission line, with a continually online trained (COT) artificial neural network (ANN) controller to identify the turbogenerator, and another COT ANN to control the turbogenerator. This identifier/controller augments/replaces the automatic voltage regulator and the turbine governor. Results are presented to show that this COT ANN identifier/controller has the potential to allow turbogenerators to operate more closely to their steady-state stability limits and nevertheless “ride through” severe transient disturbances such as three phase faults. This allows greater usage …
Comparison Of Fdtd Algorithms For Subcellular Modeling Of Slots In Shielding Enclosures, Kuang-Ping Ma, Min Li, James L. Drewniak, Todd H. Hubing, Thomas Van Doren
Comparison Of Fdtd Algorithms For Subcellular Modeling Of Slots In Shielding Enclosures, Kuang-Ping Ma, Min Li, James L. Drewniak, Todd H. Hubing, Thomas Van Doren
Electrical and Computer Engineering Faculty Research & Creative Works
Subcellular modeling of thin slots in the finite-difference time-domain (FDTD) method is investigated. Two subcellular algorithms for modeling thin slots with the FDTD method are compared for application to shielding end osures in electromagnetic compatibility (EMC). The stability of the algorithms is investigated, and comparisons between the two methods for slots in planes, and slots in loaded cavities are made. Results for scattering from a finite-length slot in an infinite plane employing one of the algorithms are shown to agree well with published experimental results, and power delivered to an enclosure with a slot agree well with results measured for …
Stability Of Discrete-Time Matrix Polynomials, Khanh Tu Ngo, Kelvin T. Erickson
Stability Of Discrete-Time Matrix Polynomials, Khanh Tu Ngo, Kelvin T. Erickson
Electrical and Computer Engineering Faculty Research & Creative Works
This paper derives conditions for the stability of discrete-time systems that can be modeled by a vector difference equation, where the variables are m x 1 vectors and the coefficients are m x m matrices. Stability of the system is related to the locations of the roots of the determinant of a real m x m matrix polynomial of nth order. In this case, sufficient conditions for the system to be stable are derived. The conditions are imposed on the infinity norm of two matrices constructed from the coefficient matrices and do not require the computation of the determinant polynomial. …
The Multirate Method For Simulation Of Power System Dynamics, J. G. Chen, Mariesa Crow
The Multirate Method For Simulation Of Power System Dynamics, J. G. Chen, Mariesa Crow
Electrical and Computer Engineering Faculty Research & Creative Works
In this paper, the multirate method is introduced to analyse power system behavior for systems with widely varying time constants. Estimates for computational speed-up are derived based on a linear system approach. The method is applied to a small power system example and the results, both in terms of accuracy and computation time, are compared to traditional simulation methods
Coperite-Computer-Aided Tool For Power Engineering Research, Instruction, Training And Education, Badrul H. Chowdhury, D. E. Clark
Coperite-Computer-Aided Tool For Power Engineering Research, Instruction, Training And Education, Badrul H. Chowdhury, D. E. Clark
Electrical and Computer Engineering Faculty Research & Creative Works
A graphics-oriented, primarily PC-based tool for education, research, and training in power engineering is introduced. The tool, called COPERITE, has all user interfaces resident on an IBM-386 microcomputer. Menus and windows are used for the interface, and attractive graphical representations and displays are included. Application programs that are interfaced are power flow, contingency analysis, economic dispatch, security-constrained dispatch, system stability, and fault analysis. These programs are executed on a VAX 8800 computer mainly for speed of execution. Information exchange between the PC and the VAX is made through an Ethernet connection which is transparent to the user. Results of execution …
The Parallel Implementation Of The Waveform Relaxation Method For Transient Stability Simulations, Marija D. Ilić, Mariesa Crow
The Parallel Implementation Of The Waveform Relaxation Method For Transient Stability Simulations, Marija D. Ilić, Mariesa Crow
Electrical and Computer Engineering Faculty Research & Creative Works
In this paper, the authors extend the results of their earlier paper on waveform relamtion (WR), which is a parallel algorithm for transient stability analysis. The WR algorithm is extended to a structure-preserving power system model in which the loads are retained. This results in a system of differential/ algebraic equations (DAEs). Power systems exhibit several unique dynamic properties which may be exploited in an advantageous manner by the WR algorithm. This leads to a greater computational efficiency than most other direct methods of simulation. This paper presents several theoretical results as well as computational results on parallel implementation.