Computer Engineering Commons^™

A Discrete-Time Direct-Torque And Flux Control For Direct-Drive Pmsg Wind Turbines, Zhe Zhang, Yue Zhao, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a novel discrete-time direct-torque and flux control (DTFC) scheme for a permanent-magnet synchronous generator (PMSG) used in a variable-speed direct-drive wind power generation system. The proposed DTFC does not rely on machine parameters, such as the inductances and permanent-magnet flux linkage, while the main advantages of the DTC, e.g., fast dynamic response and no need of coordinate transform, are preserved. The stator flux linkage is estimated by an adaptive low-pass filter (LPF), in which a variable cutoff frequency is used. The adaptive LPF stator flux observer can achieve high estimation precision over a wide operating range of …

An Adaptive Quasi-Sliding-Mode Rotor Position Observer-Based Sensorless Control For Interior Permanent Magnet Synchronous Machines, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

Advantages such as parameter insensitivity and high robustness to system structure uncertainty make the sliding-mode observer (SMO) a promising solution for sensorless control of interior permanentmagnet synchronousmachines (IPMSMs). In practical industry applications, in order to utilize digital controllers and achieve comparable performance under a lower sampling frequency, a discrete-time or quasi-SMO (QSMO) is commonly used. However, because of the saliency of an IPMSM, the magnitude of the extended electromotive force (EMF) will change with load (torque and/or speed) variations, whichmakes it challenging for the QSMO to estimate the extended EMF accurately. Without proper observer parameters, a phase shift will be …

An Extended Flux Model-Based Rotor Position Estimator For Sensorless Control Of Interior Permanent Magnet Synchronous Machines, Yue Zhao, Zhe Zhang, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

Starting from the classical dynamic model of interior permanent magnet synchronous machines (IPMSMs) expressed in the stationary reference frame, this paper presents a mathematical model reconstruction process for IPMSMs, from which an extended flux-based IPMSM model is derived. Compared with the commonly used extended electromotive force-based model, the extended flux-based model has notable advantages of simpler model structure and less sensitive to machine parameter and speed variations. An extended flux model-based position estimator is then proposed for sensorless control of an IPMSM by utilizing a sliding-mode observer with a dynamic position compensator. The latter improves the dynamic performance and low-speed …

Sensorless Control Of Surface-Mounted Permanent-Magnet Synchronous Machines For Low-Speed Operation Based On High-Frequency Square-Wave Voltage Injection, Yue Zhao, Zhe Zhang, Cong Ma, Wei Qiao, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This paper proposes a high-frequency signal injection-based position estimation scheme for surface-mounted permanent-magnet synchronous machines (SPMSM) operating in the low-speed range. A square-wave voltage vector is injected in the estimated rotating reference frame. The rotor position information is then extracted from the envelopes of the resulting induced high-frequency currents in the stationary reference frame. The proposed position estimation method has almost no dependence on machine asymmetric properties and, therefore, is well suited for SPMSM applications. Simulation results are provided to verify the effectiveness of the proposed method from 1 Hz to 50 Hz electric fundamental frequency under all load conditions. …

Model Reference Adaptive System-Based Speed Estimators For Sensorless Control Of Interior Permanent Magnet Synchronous Machines, Yue Zhao, Wei Qiao, Long Wu

Department of Electrical and Computer Engineering: Faculty Publications

In this work, speed estimators are designed based on a model reference adaptive system (MRAS) for sensorless control of interior permanent magnet synchronous machines (IPMSMs). To provide better filtering performance and reduce the noise contents in the estimated speed, an adaptive line enhancer is proposed to work with a sliding-mode observer to provide an improved reference model for speed estimation. In addition, a heterodyning speed adaption scheme is proposed to replace the conventional speed adaption mechanism. The proposed MRASbased speed estimator has two different operating modes, which are suitable for generator- and motor-type applications, respectively. The effectiveness of the proposed …

Frequency Demodulation-Aided Condition Monitoring For Drivetrain Gearboxes, Dingguo Lu, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Condition monitoring and fault diagnosis (CMFD) of drivetrain gearboxes has become a prominent challenge in assorted industries. Current-based diagnostic techniques have significant advantages over traditional vibration-based techniques in terms of accessibility, cost, implementation and reliability. This paper proposes a current-based, frequency demodulation-aided CMFD method for drivetrain gearboxes. A mathematical model is developed for a drivetrain consisting of a two-stage gearbox and a permanent magnet synchronous generator (PMSG), from which the characteristic frequencies of gearbox faults in the PMSG stator current are derived. An adaptive signal resampling method is proposed to convert the variable fault characteristic frequencies to constant values for …

Current-Based Fault Detection For Wind Turbine Systems Via Hilbert-Huang Transform, Dingguo Lu, Wei Qiao, Xiang Gong, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

Mechanical failures of wind turbines represent a significant cost in both repairs and downtime. Detecting incipient faults of wind turbine components permits maintenance to be scheduled and failed parts to be repaired or replaced before causing failures of other components or catastrophic failure of the system. This paper proposes a Hilbert-Huang transform (HHT)-based algorithm to effectively extract fault signatures in generator current signals for wind turbine fault diagnosis by using the HHT’s capability of accurately representing the instantaneous amplitude and frequency of nonlinear and nonstationary signals. A phase-lock-loop (PLL) method is integrated to estimate wind turbine rotating speed, which is …

Low-Power Analog Processing For Sensing Applications: Low-Frequency Harmonic Signal Classification, Daniel J. White, Peter E. Williams, Michael W. Hoffman, Sina Balkir

Department of Electrical and Computer Engineering: Faculty Publications

A low-power analog sensor front-end is described that reduces the energy required to extract environmental sensing spectral features without using Fast Fourier Transform (FFT) or wavelet transforms. An Analog Harmonic Transform (AHT) allows selection of only the features needed by the back-end, in contrast to the FFT, where all coefficients must be calculated simultaneously. We also show that the FFT coefficients can be easily calculated from the AHT results by a simple back-substitution. The scheme is tailored for low-power, parallel analog implementation in an integrated circuit (IC). Two different applications are tested with an ideal front-end model and compared to …

Fiber-Optic Refractometer Based On An Etched High-Q Π-Phase-Shifted Fiber-Bragg-Grating, Qi Zhang, Natale J. Ianno, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

We present a compact and highly-sensitive fiber-optic refractometer based on a high-Q π-phase-shifted fiber-Bragg-grating (πFBG) that is chemically etched to the core of the fiber. Due to the π phase-shift, a strong πFBG forms a high-Q optical resonator and the reflection spectrum features an extremely narrow notch that can be used for highly sensitivity refractive index measurement. The etched πFBG demonstrated here has a diameter of ~9.3 μm and a length of only 7 mm, leading to a refractive index responsivity of 2.9 nm/RIU (RIU: refractive index unit) at an ambient refractive index of 1.318. The reflection spectrum of the …

Optimal Receiver Antenna Location In Indoor Environment Using Dynamic Differential Evolution And Genetic Algorithm, Shu-Han Liao, Chien-Hung Chen, Chien-Ching Chiu, Min-Hui Ho, Tadeusz A. Wysocki, Beata J. Wysocki

Department of Electrical and Computer Engineering: Faculty Publications

Using the impulse responses of these multipath channels, the bit error rate (BER) performance for binary pulse amplitude modulation impulse radio ultra-wideband communication system is calculated. The optimization location of receiving antenna is investigated by dynamic differential evolution (DDE) and genetic algorithm (GA) to minimize the outage probability. Numerical results show that the performance for reducing BER and outage probability by DDE algorithm is better than that by GA.

Broadening The Cloaking Bandwidth With Non-Foster Metasurfaces, Pai-Yen Chen, Christos Argyropoulos, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We introduce the concept and practical design of broadband, ultrathin cloaks based on non-Foster, negatively capacitive metasurfaces. By using properly tailored, active frequency-selective screens conformal to an object, within the realm of a practical realization, we show that it is possible to drastically reduce the scattering over a wide frequency range in the microwave regime, orders of magnitude broader than any available passive cloaking technology. The proposed active cloak may impact not only invisibility and camouflaging, but also practical antenna and sensing applications.

Terahertz Antenna Phase Shifters Using Integrally-Gated Graphene Transmission-Lines, Pai-Yen Chen, Christos Argyropoulos, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

We propose the concept and design of terahertz (THz) phase shifters for phased antenna arrays based on integrally- gated graphene parallel-plate waveguides (GPPWGs). We show that an active transmission-line may be realized by combining GPPWGs with double-gate electrodes, in which the applied gate voltage can control the guiding properties of the gated sections. This may enable the realization of THz electronic switches and tunable loaded-lines for sub mm-wave antenna systems. Based on these active components, we theoretically and numerically demonstrate several digital and analog phase shifter designs for THz frequencies, with a wide range of phase shifts and small return …

Negative Refraction, Gain And Nonlinear Effects In Hyperbolic Metamaterials, Christos Argyropoulos, Nasim Mohammadi Estakhri, Francesco Monticone, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

The negative refraction and evanescent-wave canalization effects supported by a layered metamaterial structure obtained by alternating dielectric and plasmonic layers is theoretically analyzed. By using a transmission-line analysis, we formulate a way to rapidly analyze the negative refraction operation for given available materials over a broad range of frequencies and design parameters, and we apply it to broaden the bandwidth of negative refraction. Our analytical model is also applied to explore the possibility of employing active layers for loss compensation. Nonlinear dielectrics can also be considered within this approach, and they are explored in order to add tunability to the …

Testing Robustness Of Relative Complexity Measure Method Constructing Robust Phylogenetic Trees For Galanthus L. Using The Relative Complexity Measure, Yasin Bakis, Hasan H. Otu, Nivart Tasci, Cem Meydan, Nese Bilgin, Sirri Yuzbasioglu, O Ugur Sezerman

Department of Electrical and Computer Engineering: Faculty Publications

Background: Most phylogeny analysis methods based on molecular sequences use multiple alignment where the quality of the alignment, which is dependent on the alignment parameters, determines the accuracy of the resulting trees. Different parameter combinations chosen for the multiple alignment may result in different phylogenies. A new non-alignment based approach, Relative Complexity Measure (RCM), has been introduced to tackle this problem and proven to work in fungi and mitochondrial DNA.

Result: In this work, we present an application of the RCM method to reconstruct robust phylogenetic trees using sequence data for genus Galanthus obtained from different regions in Turkey. Phylogenies …

Transparent, Flexible, And Solid-State Supercapacitors Based On Graphene Electrodes, Y. Gao, Y. S. Zhou, W. Xiong, L. J. Jiang, M. Mahjouri-Samani, P. Thirugnanam, X. Huang, M. M. Wang, L. Jiang, Y. F. Lu

Department of Electrical and Computer Engineering: Faculty Publications

In this study, graphene-based supercapacitors with optical transparency and mechanical flexibility have been achieved using a combination of poly(vinyl alcohol)/ phosphoric acid gel electrolyte and graphene electrodes.An optical transmittance of ∼67% in a wavelength range of 500-800 nm and a 92.4% remnant capacitance under a bending angle of 80◦ have been achieved for the supercapacitors. The decrease in capacitance under bending is ascribed to the buckling of the graphene electrode in compression. The supercapacitors with high optical transparency, electrochemical stability, and mechanical flexibility hold promises for transparent and flexible electronics.

Mass Sensor, Mathias M. Schubert, Eva Schubert, Tino Hofmann, Daniel Schmidt

Department of Electrical and Computer Engineering: Faculty Publications

A mass sensor is provided for determining the mass of small objects. The mass sensor has a plurality of nanostructures attached to a substrate. The nanostructures and the substrate are irradiated with an electromagnetic wave to determine a first mechanical-electromagnetic wave to determine a first mechanical-electromagnetic resonant frequency of the mass sensor. After a particle is attached to the nanostructures, the substrate and the nanostructures to which the particle is attached are irradiated with an electromagnetic wave to determine a second mechanical electromagnetic resonant frequency of the mass sensor. A mass of the particle is determined based on a difference …

Terahertz Resonator, Eva Schubert, Mathias M. Schubert, Tino Hofmann

Department of Electrical and Computer Engineering: Faculty Publications

A tunable terahertz resonator includes a semiconductor Substrate and a metal layer contacting a surface of the semiconductor substrate. A depletion layer is formed in the semiconductor substrate near an interface between the metal layer and the semiconductor Substrate. A chiral nanostructure is coupled to the substrate or the metal layer, the chiral nanostructure including a conducting or semiconducting material and having an inductance. A bias circuit applies a bias Voltage across the metal layer and the semiconductor Substrate to control a capacitance of a tunable capacitor that includes the depletion layer. The chiral nanostructure and the tunable capacitor form …

Robust Subspace Estimation Using Low-Rank Optimization. Theory And Applications In Scene Reconstruction, Video Denoising, And Activity Recognition., Omar Oreifej

Electronic Theses and Dissertations

In this dissertation, we discuss the problem of robust linear subspace estimation using low-rank optimization and propose three formulations of it. We demonstrate how these formulations can be used to solve fundamental computer vision problems, and provide superior performance in terms of accuracy and running time. Consider a set of observations extracted from images (such as pixel gray values, local features, trajectories . . . etc). If the assumption that these observations are drawn from a liner subspace (or can be linearly approximated) is valid, then the goal is to represent each observation as a linear combination of a compact …

Measuring The Evolving Internet Ecosystem With Exchange Points, Mohammad Zubair Ahmad

Electronic Theses and Dissertations

The Internet ecosystem comprising of thousands of Autonomous Systems (ASes) now include Internet eXchange Points (IXPs) as another critical component in the infrastructure. Peering plays a significant part in driving the economic growth of ASes and is contributing to a variety of structural changes in the Internet. IXPs are a primary component of this peering ecosystem and are playing an increasing role not only in the topology evolution of the Internet but also inter-domain path routing. In this dissertation we study and analyze the overall affects of peering and IXP infrastructure on the Internet. We observe IXP peering is enabling …

Influence Of Task-Role Mental Models On Human Interpretation Of Robot Motion Behavior, Scott Ososky

Electronic Theses and Dissertations

The transition in robotics from tools to teammates has begun. However, the benefit autonomous robots provide will be diminished if human teammates misinterpret robot behaviors. Applying mental model theory as the organizing framework for human understanding of robots, the current empirical study examined the influence of task-role mental models of robots on the interpretation of robot motion behaviors, and the resulting impact on subjective ratings of robots. Observers (N = 120) were exposed to robot behaviors that were either congruent or incongruent with their task-role mental model, by experimental manipulation of preparatory robot task-role information to influence mental models (i.e., …

The Course Development For Microcomputer Systems Technology: Preliminary Study, Yu Wang, Alex Wong, Aparicio Carranza

Publications and Research

The course of Microcomputer Systems Technology has been one of the core courses in the Computer Engineering Technology curriculum (Bachelor of Technology in CET) at the New York City College of Technology of the City University of New York. The Intel microprocessor in PC based computer was the chosen hardware in this course. The assembly and C++ languages were crucial tools in the study of microprocessor organization. We currently focused mainly on the topic of PC computer parallel interface technology. However, we did not pay particular attention to the integration of current programmable peripheral components, such as USB (universal serial …

A P2p Computing System For Overlay Networks, Grzegorz Chmaj, Krzysztof Walkowiak

Electrical & Computer Engineering Faculty Research

A distributed computing system is able to perform data computation and distribution of results at the same time. The input task is divided into blocks, which are then sent to system participants that offer their resources in order to perform calculations. Next, a partial result is sent back by the participants to the task manager (usually one central node). In the case when system participants want to get the final result, the central node may become overloaded, especially if many nodes request the result at the same time. In this paper we propose a novel distributed computation system, which does …

Dnad, A Simple Tool For Automatic Differentiation Of Fortran Codes Using Dual Numbers, Wenbin Yu, Maxwell Blair

Mechanical and Aerospace Engineering Faculty Publications

DNAD (dual number automatic differentiation) is a simple, general-purpose tool to automatically differentiate Fortran codes written in modern Fortran (F90/95/2003) or legacy codes written in previous version of the Fortran language. It implements the forward mode of automatic differentiation using the arithmetic of dual numbers and the operator overloading feature of F90/95/2003. Very minimum changes of the source codes are needed to compute the first derivatives of Fortran programs. The advantages of DNAD in comparison to other existing similar computer codes are its programming simplicity, extensibility, and computational efficiency. Specifically, DNAD is more accurate and efficient than the popular complex-step …

Technology Corner: Calculating The Number Of Android Lock Patterns: An Unfinished Study In Number Theory, Gary C. Kessler

Security Studies & International Affairs - Daytona Beach

"Although one is unlikely to ever want to brute-force an Android lock pattern, many do wonder about the relative strength of the lock pattern versus a multi-digit personal identification number (PIN). It becomes obvious pretty quickly that there are many more lock patterns than the 10,000 possible four-digit PINs."--from the introduction.

Epistemic Updates On Algebras, Alexander Kurz, Alessandra Palmigiano

Engineering Faculty Articles and Research

We develop the mathematical theory of epistemic updates with the tools of duality theory. We focus on the Logic of Epistemic Actions and Knowledge (EAK), introduced by Baltag-Moss-Solecki, without the common knowledge operator. We dually characterize the product update construction of EAK as a certain construction transforming the complex algebras associated with the given model into the complex algebra associated with the updated model. This dual characterization naturally generalizes to much wider classes of algebras, which include, but are not limited to, arbitrary BAOs and arbitrary modal expansions of Heyting algebras (HAOs). As an application of this dual characterization, we …

Dynamic Sequent Calculus For The Logic Of Epistemic Actions And Knowledge, Giuseppe Greco, Alexander Kurz, Alessandra Palmigiano

Engineering Faculty Articles and Research

"Dynamic Logics (DLs) form a large family of nonclassical logics, and perhaps the one enjoying the widest range of applications. Indeed, they are designed to formalize change caused by actions of diverse nature: updates on the memory state of a computer, displacements of moving robots in an environment, measurements in models of quantum physics, belief revisions, knowledge updates, etc. In each of these areas, DL-formulas express properties of the model encoding the present state of affairs, as well as the pre- and post-conditions of a given action. Actions are semantically represented as transformations of one model into another, encoding the …

Nominal Regular Expressions For Languages Over Infinite Alphabets, Alexander Kurz, Tomoyuki Suzuki, Emilio Tuosto

Engineering Faculty Articles and Research

We propose regular expressions to abstractly model and study properties of resource-aware computations. Inspired by nominal techniques – as those popular in process calculi – we extend classical regular expressions with names (to model computational resources) and suitable operators (for allocation, deallocation, scoping of, and freshness conditions on resources). We discuss classes of such nominal regular expressions, show how such expressions have natural interpretations in terms of languages over infinite alphabets, and give Kleene theorems to characterise their formal languages in terms of nominal automata.

Directed Test Suite Augmentation, Zhihong Xu

School of Computing: Dissertations, Theses, and Student Research

Test suite augmentation techniques are used in regression testing to identify code elements affected by changes and to generate test cases to cover those elements. Whereas methods and techniques to find affected elements have been extensively researched in regression testing, the problem of generating new test cases to cover these elements cost-effectively has rarely been studied. We believe that reusing existing test cases will help us achieve this task. This research develops test suite augmentation techniques that reuse existing test cases to automatically generate new test cases to cost-effectively cover affected elements. We begin by using two dynamic test case …

Performance Evaluation Of Data Intensive Computing In The Cloud, Bhagavathi Kaza

UNF Graduate Theses and Dissertations

Big data is a topic of active research in the cloud community. With increasing demand for data storage in the cloud, study of data-intensive applications is becoming a primary focus. Data-intensive applications involve high CPU usage for processing large volumes of data on the scale of terabytes or petabytes. While some research exists for the performance effect of data intensive applications in the cloud, none of the research compares the Amazon Elastic Compute Cloud (Amazon EC2) and Google Compute Engine (GCE) clouds using multiple benchmarks. This study performs extensive research on the Amazon EC2 and GCE clouds using the TeraSort, …

Performance Evaluation Of Linq To Hpc And Hadoop For Big Data, Ravishankar Sivasubramaniam

UNF Graduate Theses and Dissertations

There is currently considerable enthusiasm around the MapReduce paradigm, and the distributed computing paradigm for analysis of large volumes of data. The Apache Hadoop is the most popular open source implementation of MapReduce model and LINQ to HPC is Microsoft's alternative to open source Hadoop. In this thesis, the performance of LINQ to HPC and Hadoop are compared using different benchmarks.

To this end, we identified four benchmarks (Grep, Word Count, Read and Write) that we have run on LINQ to HPC as well as on Hadoop. For each benchmark, we measured each system’s performance metrics (Execution Time, Average CPU …