Engineering Commons^™

Introducing Phonetic Information To Speaker Embedding For Speaker Verification, Yi Liu, Liang He, Michael T. Johnson

Electrical and Computer Engineering Faculty Publications

Phonetic information is one of the most essential components of a speech signal, playing an important role for many speech processing tasks. However, it is difficult to integrate phonetic information into speaker verification systems since it occurs primarily at the frame level while speaker characteristics typically reside at the segment level. In deep neural network-based speaker verification, existing methods only apply phonetic information to the frame-wise trained speaker embeddings. To improve this weakness, this paper proposes phonetic adaptation and hybrid multi-task learning and further combines these into c-vector and simplified c-vector architectures. Experiments on National Institute of Standards and Technology …

Optimal Combinations Of Utility Level Renewable Generators For A Net Zero Energy Microgrid Considering Different Utility Charge Rates, Evan S. Jones, Huangjie Gong, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

High initial investment and the intermittent nature of resources are major challenges for large scale renewable generation. The size of photovoltaic (PV) and wind turbine (WT) farms in the microgrid needs optimized to avoid curtailment and to efficiently meet the demand of a power system. Battery energy storage systems (BESSs) may also be used to improve flexibility. This paper explores the optimal sizing for PV and wind generators, as well as a BESS at the utility level for a large grid-connected net zero energy (NZE) hybrid microgrid considering characteristics such as initial investment, levelized cost of energy (LCOE), operating costs, …

Smart Plug And Circuit Breaker Technologies For Residential Buildings In The Us, Rosemary E. Alden, Peng Han, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

A significant proportion of the total energy in conventional homes across the United States is used by electric plug loads, which include various electronic devices and home appliances, excluding the heating, ventilation and air conditioning (HVAC) units and electric water heaters. Considerable energy savings are expected to be possible by managing these plug loads effectively based on user behavior data. Smart plugs and circuit breakers that can control and monitor energy usage on a real-time basis are becoming increasingly popular alongside the rapid development of smart home energy management. This paper reviews the recent advances on the subject matter with …

Overview Of Flywheel Systems For Renewable Energy Storage With A Design Study For High-Speed Axial-Flux Permanent-Magnet Machines, Murat G. Kesgin, Peng Han, Narges Taran, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

Flywheel energy storage is considered in this paper for grid integration of renewable energy sources due to its inherent advantages of fast response, long cycle life and flexibility in providing ancillary services to the grid, such as frequency regulation, voltage support, etc. The fundamentals of the technology and recent developments are reviewed, firstly with an emphasis on the design considerations and performance metrics. Then the progress and development trends in electric motor/generators employed in flywheel energy storage systems (FESS) are summarized, showing the potential of axial-flux permanent-magnet (AFPM) machines in such applications. Design examples of high-speed AFPM machines are provided …

Systematic Comparison Of Two Axial Flux Pm Machine Topologies: Yokeless And Segmented Armature Versus Single Sided, Narges Taran, Greg Heins, Vandana Rallabandi, Dean Patterson, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper systematically compares two axial flux permanent magnet (AFPM) machines designed for a university student racing car application: a double-rotor single-stator yokeless and segmented armature (YASA) structure, and a single- stator single-rotor configuration. Both machines are optimized for minimum loss and active weight using 3D finite element analysis and the highest performing candidate designs are compared in more detail. The studies indicate that the benefits offered by the YASA configuration over the single-stator single-rotor machine are achieved only for specific designs that are heavier. For the design space with lower mass, albeit with increased losses, the Pareto front designs …

Enhanced Crystallinity Of Triple-Cation Perovskite Film Via Doping Nh4Scn, Ziji Liu, Detao Liu, Hao Chen, Long Ji, Hualin Zheng, Yiding Gu, Feng Wang, Zhi Chen, Shibin Li

Electrical and Computer Engineering Faculty Publications

The trap-state density in perovskite films largely determines the photovoltaic performance of perovskite solar cells (PSCs). Increasing the crystal grain size in perovskite films is an effective method to reduce the trap-state density. Here, we have added NH₄SCN into perovskite precursor solution to obtain perovskite films with an increased crystal grain size. The perovskite with increased crystal grain size shows a much lower trap-state density compared with reference perovskite films, resulting in an improved photovoltaic performance in PSCs. The champion photovoltaic device has achieved a power conversion efficiency of 19.36%. The proposed method may also impact other optoelectronic …

On The Optimal Energy Controls For Large Scale Residential Communities Including Smart Homes, Huangjie Gong, Vandana Rallabandi, Michael L. Mcintyre, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

Residences with smart home energy management (HEM) systems and solar generation are modifying domestic load profiles. Moreover, the growing penetration of solar photovoltaic (PV) energy brings the total net power demand further down as houses become local generators. High PV penetration introduces technical challenges for the power system including the "duck curve". This paper proposes a co-simulation framework for high PV penetration smart energy communities which allows the simultaneous simulation of home energy consumption along with control algorithms for each house, as well as system power flow. Models are developed and presented for one of the largest rural field demonstrators …

A Hybrid Analytical And Fe-Based Method For Calculating Ac Eddy Current Winding Losses Taking 3d Effects Into Account, Narges Taran, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper proposes a new hybrid analytical and numerical FE-based method for calculating ac eddy current losses in wire windings and demonstrates its applicability for axial flux electric machines. The method takes into account 3D field effects in order to achieve accurate results and yet greatly reduce computational efforts. It is also shown that hybrid methods based on 2D FE models, which require semi-empirical correction factors, may over-estimate the eddy current losses. The new 3D FE-based method is advantageous as it employs minimum simplifications and considers the end turns in the eddy current path, the magnetic flux density variation along …

Measurement And Estimation Of The Equivalent Circuit Parameters For Multi-Mw Battery Systems, Oluwaseun M. Akeyo, Vandana Rallabandi, Nicholas Jewell, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper proposes and validates through simulations and measurements, a procedure for the determining the equivalent circuit parameters of large utility-scale batteries. It is considered that a large battery includes multiple cells connected in series and parallel, and therefore, its equivalent circuit can be represented as a series-parallel network of state of charge (SOC) dependent resistors and capacitors. Tests for determining these equivalent circuit parameters are proposed. These tests involve subjecting the battery energy storage system (BESS) to multiple charge and discharge cycles, while monitoring the terminal voltage and current response. A method for post-processing and analyzing the measurements in …

On The Control Of A Solid State Transformer For Multi-Mw Utility-Scale Pv-Battery Systems, Yibin Zhang, Oluwaseun M. Akeyo, Jiangbiao He, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

The utility-scale photovoltaic (PV)-battery systems typically include multiple power converters connected to the grid via traditional line frequency transformers (LFT), which may be considered bulky, and inefficient when compared with the emerging solid state transformers (SST). This paper proposes a SST with power and voltage controls for utility-scale PV-battery systems. The PV system was modeled based on available data from a universal solar facility located in Kentucky, USA. Furthermore, this paper provides detailed controller designs for the proposed utility-scale PV-battery system based on a SST which includes: the PV-side dual-active bridge (DAB) converter tracks the maximum power point, the PV …

Axial-Field Vernier-Type Flux Modulation Machines For Low-Speed Direct-Drive Applications, Vandana Rallabandi, Peng Han, Murat G. Kesgin, Narges Taran, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper proposes different configurations of axial-field machines featuring a very large ratio of the number of rotor poles to stator teeth and coils suitable for low-speed direct-drive traction applications. The machines have a single rotor with spoke-type permanent magnets and the stator teeth include auxiliary slots, the function of which is to enhance the high-polarity component of the stator magnetomotive force interacting with the rotor to produce a net torque. The machines can be constructed with three or two phases, in which case they inherently exhibit high tolerance to faults due to the combined effect of a lack of …

Load Variation Reduction By Aggregation In A Community Of Rooftop Pv Residences, Huangjie Gong, Vandana Rallabandi, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper performs computational studies and develops control schemes for a virtual power plant (VPP) network formed by a community of homes with rooftop solar PV generation, and battery energy storage. Appropriate control and scheduling of the battery operations, and peer-peer power flow between the homes provide a possible solutions for reducing the higher costs and uncertainties brought to grid by high solar PV penetration. The residential community studied here includes twelve homes categorized into four types depending on whether they have energy storage or rooftop solar PV panels. The homes exchange power among themselves, and the real-time electricity rate …

Modeling And Simulation Of A Utility-Scale Battery Energy Storage System, Oluwaseun M. Akeyo, Vandana Rallabandi, Nicholas Jewell, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper presents the modeling and simulation study of a utility-scale MW level Li-ion based battery energy storage system (BESS). A runtime equivalent circuit model, including the terminal voltage variation as a function of the state of charge and current, connected to a bidirectional power conversion system (PCS), was developed based on measurements from an operational utility-scale battery demonstrator. The accelerated response of the battery unit was verified by pulse discharging it from maximum to minimum SOC and its application for grid resiliency was demonstrated through an example droop control frequency response. For the purpose of validating the equivalent BESS …

Beneficial Reuse Of Industrial Co2 Emissions Using A Microalgae Photobioreactor: Waste Heat Utilization Assessment, Daniel T. Mohler, Michael H. Wilson, Zhen Fan, John G. Groppo, Mark Crocker

Center for Applied Energy Research Faculty and Staff Publications

Microalgae are a potential means of recycling CO₂ from industrial point sources. With this in mind, a novel photobioreactor (PBR) was designed and deployed at a coal-fired power plant. To ascertain the feasibility of using waste heat from the power plant to heat algae cultures during cold periods, two heat transfer models were constructed to quantify PBR cooling times. The first, which was based on tabulated data, material properties and the physical orientation of the PBR tubes, yielded a range of heat transfer coefficients of 19–64 W m⁻² K⁻¹ for the PBR at wind speeds of 1–10 …

Latent Class Model With Application To Speaker Diarization, Liang He, Xianhong Chen, Can Xu, Yi Liu, Jia Liu, Michael T. Johnson

Electrical and Computer Engineering Faculty Publications

In this paper, we apply a latent class model (LCM) to the task of speaker diarization. LCM is similar to Patrick Kenny’s variational Bayes (VB) method in that it uses soft information and avoids premature hard decisions in its iterations. In contrast to the VB method, which is based on a generative model, LCM provides a framework allowing both generative and discriminative models. The discriminative property is realized through the use of i-vector (Ivec), probabilistic linear discriminative analysis (PLDA), and a support vector machine (SVM) in this work. Systems denoted as LCM-Ivec-PLDA, LCM-Ivec-SVM, and LCM-Ivec-Hybrid are introduced. In addition, three …

Influence Spread In Two-Layer Interdependent Networks: Designed Single-Layer Or Random Two-Layer Initial Spreaders?, Hana Khamfroush, Nathaniel Hudson, Samuel Iloo, Mahshid R. Naeini

Computer Science Faculty Publications

Influence spread in multi-layer interdependent networks (M-IDN) has been studied in the last few years; however, prior works mostly focused on the spread that is initiated in a single layer of an M-IDN. In real world scenarios, influence spread can happen concurrently among many or all components making up the topology of an M-IDN. This paper investigates the effectiveness of different influence spread strategies in M-IDNs by providing a comprehensive analysis of the time evolution of influence propagation given different initial spreader strategies. For this study we consider a two-layer interdependent network and a general probabilistic threshold influence spread model …

A Traffic-Aware Approach For Enabling Unmanned Aerial Vehicles (Uavs) In Smart City Scenarios, Hesham El-Sayed, Moumena Chaqfa, Sherali Zeadally, Deepak Puthal

Information Science Faculty Publications

In smart cities, vehicular applications require high computation capabilities and low-latency communication. Edge computing offers promising solutions for addressing these requirements because of several features, such as geo-distribution, mobility, low latency, heterogeneity, and support for real-time interactions. To employ network edges, existing fixed roadside units can be equipped with edge computing servers. Nevertheless, there are situations where additional infrastructure units are required to handle temporary high traffic loads during public events, unexpected weather conditions, or extreme traffic congestion. In such cases, the use of flying roadside units are carried by unmanned aerial vehicles (UAVs), which provide the required infrastructure for …

Waved: A Coreless Axial Flux Pm Motor For Drive Systems With Constant Power Operation, Narges Taran, Vandana Rallabandi, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

In this paper, a two-phase coreless AFPM machine with wave winding, 2-stators, and 3-rotors for traction applications is studied. A highly general optimization method, employing 3D FEA as the computational engine is employed. Number of poles in addition to other geometrical variables are included as independent optimization variables. A method for extending the speed range by rotating one of the stator discs with respect to the other at constant power operation is proposed. An inverter configuration including Si and wide band gap devices is proposed to be employed in conjunction with the machine under study. The study includes a comparison …

Modeling And Control Of A Multiport Converter Based Ev Charging Station With Pv And Battery, Yibin Zhang, Jiangbiao He, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

As an environmental friendly vehicle, the increasing number of electrical vehicles (EVs) leads to a pressing need of widely distributed charging stations, especially due to the limited on-board battery capacity. However, fast charging stations, especially super-fast charging stations may stress power grid with potential overload at peaking time, sudden power gap and voltage sag. This paper discusses the detailed modeling of a multiport converter based EV charging station integrated with PV power generation, and battery energy storage system, by using ANSYS TwinBuilder. In this paper, the control scheme and combination of PV power generation, EV charging station, and battery energy …

Electric Aircraft System Co-Simulation Including Body, Propeller, Propulsion, And Energy Storage Models, Damien Lawhorn, Vandana Rallabandi, Dan M. Ionel

Power and Energy Institute of Kentucky Faculty Publications

This paper discusses the multi physics modeling of an electric aircraft with distributed electric propulsion. Mathematical models for the aircraft body, propellers, propulsive motors, power electronics inverters, and batteries are developed. Two types of models are proposed for the power electronics inverters and electric machines, namely, average models which allow study of the aircraft performance under a specified mission profile, and detailed switching models used for transient examination. A new simulation framework was developed to allow communication between these two types of models so that losses and thermal stresses in the power electronics converters can be estimated especially during takeoff, …

Anonymous And Efficient Message Authentication Scheme For Smart Grid, Libing Wu, Jing Wang, Sherali Zeadally, Debiao He

Information Science Faculty Publications

Smart grid has emerged as the next-generation electricity grid with power flow optimization and high power quality. Smart grid technologies have attracted the attention of industry and academia in the last few years. However, the tradeoff between security and efficiency remains a challenge in the practical deployment of the smart grid. Most recently, Li et al. proposed a lightweight message authentication scheme with user anonymity and claimed that their scheme is provably secure. But we found that their scheme fails to achieve mutual authentication and mitigate some typical attacks (e.g., impersonation attack, denial of service attack) in the smart grid …

Inductance Testing For Ipm Synchronous Machines According To The New Ieee Std 1812 And Typical Laboratory Practices, Vandana Rallabandi, Narges Taran, Dan M. Ionel, Ping Zhou

Power and Energy Institute of Kentucky Faculty Publications

Equivalent circuit parameters serve as the basis for performance estimation and implementation of power electronic drives controls and therefore their accurate evaluation is very important. Specified in the newly approved IEEE Std 1812, a short-circuit test can be employed, in combination with an open-circuit measurement, in order to determine the back emf and the synchronous inductance. In the case of interior permanent magnet (IPM) machines, this approach can be used only to determine the d-axis inductance and additional and separate measurements are required for the q-axis inductance. In this respect, various methods, inclusive of dc step response tests, on-load tests, …

Bamorc: A Software Package For Accurate And Robust 13C Reference Correction Of Protein Nmr Spectra, Xi Chen, Andrey Smelter, Hunter N. B. Moseley

Molecular and Cellular Biochemistry Faculty Publications

We describe Bayesian Model Optimized Reference Correction (BaMORC), a software package that performs ¹³C chemical shifts reference correction for either assigned or unassigned peak lists derived from protein NMR spectra. BaMORC provides an intuitive command line interface that allows non-nuclear magnetic resonance (NMR) experts to detect and correct ¹³C chemical shift referencing errors of unassigned peak lists at the very beginning of NMR data analysis, further lowering the bar of expertise required for effective protein NMR analysis. Furthermore, BaMORC provides an application programming interface for integration into sophisticated protein NMR data analysis pipelines, both before and after the …

Design Optimization Of Electric Machines With 3d Fea And A New Hybrid Doe-De Numerical Algorithm, Narges Taran, Vandana Rallabandi, Dan M. Ionel, Greg Heins, Dean Patterson, Ping Zhou

Power and Energy Institute of Kentucky Faculty Publications

This paper discusses the multi-objective optimization of axial flux permanent magnet (AFPM) machines with ferrite spoke-type magnets, utilizing 3D finite element models. Three-dimensional finite element analysis is computationally expensive, and furthermore, substantial computation time is expended by optimization algorithms in evaluating low performing designs whose performance is far from the optimum if the search space is not specified correctly. In this regard, this work proposes two new methods for identifying the search space. The search is limited to ranges of input geometric variables where high performing designs are likely to be found. The optimization algorithm utilized is based on surrogate …

A Comparative Study Of Methods For Calculating Ac Winding Losses In Permanent Magnet Machines, Narges Taran, Vandana Rallabandi, Dan M. Ionel, Greg Heins, Dean Patterson

Power and Energy Institute of Kentucky Faculty Publications

In this study different methods of estimating the additional ac winding loss due to eddy currents at open-circuit are explored. A comparative study of 2D and 3D FEA, and hybrid numerical and analytical methods is performed in order to recommend feasible approaches to be employed. Axial flux permanent magnet (AFPM) machine case studies are included, namely a machine with open slots and a coreless configuration. These machine topologies are expected to present a substantial amount of ac winding loss, which would therefore need to be considered during optimal design. This study is one of the first ones to compare meticulous …

Automatic Look-Up Table Based Real-Time Phase Unwrapping For Phase Measuring Profilometry And Optimal Reference Frequency Selection, Jianwen Song, Daniel L. Lau, Yo-Sung Ho, Kai Liu

Electrical and Computer Engineering Faculty Publications

For temporal phase unwrapping in phase measuring profilometry, it has recently been reported that two phases with co-prime frequencies can be absolutely unwrapped using a look-up table; however, frequency selection and table construction has been performed manually without optimization. In this paper, a universal phase unwrapping method is proposed to unwrap phase flexibly and automatically by using geometric analysis, and thus we can programmatically build a one-dimensional or two-dimensional look-up table for arbitrary two co-prime frequencies to correctly unwrap phases in real time. Moreover, a phase error model related to the defocus effect is derived to figure out an optimal …

Sliding-Mode-Observer-Based Position Estimation For Sensorless Control Of The Planar Switched Reluctance Motor, Jundi Sun, Guang-Zhong Cao, Su-Dan Huang, Yeping Peng, Jiangbiao He, Qing-Quan Qian

Electrical and Computer Engineering Faculty Publications

This paper proposes a position estimation method for a planar switched reluctance motor (PSRM). In the method, a second-order sliding mode observer (SMO) is used to achieve sensorless control of a PSRM for the first time. A sensorless closed-loop control strategy based on the SMO without a position sensor for the PSRM is constructed. The SMO mainly consists of a flux linkage estimation, an adaptive current estimation, an observing error calculation, and a position estimation section. An adaptive current observer is applied in the current estimation section to minimize the error between the measured and estimated currents and to increase …

A Systematic Study On The Effects Of Dimensional And Materials Tolerances On Permanent Magnet Synchronous Machines Based On The Ieee Std 1812, Narges Taran, Vandana Rallabandi, Dan M. Ionel, Ping Zhou, Mark Theile, Greg Heins

Power and Energy Institute of Kentucky Faculty Publications

In the process of designing and manufacturing an electrical machine, a systematic study of dimensional and material tolerances is of the utmost importance. This paper proposes a systematic method by which the effect of design specification variations on permanent magnet (PM) synchronous machine performance may be identified and quantified. The method combines design of experiments techniques, open-circuit and short-circuit physical measurements, and virtual test simulations conducted based on the recently approved IEEE Std 1812 testing guide. Three case studies, two provided by a spoke-type PM radial field machine configuration, in two designs with different electromagnetic loading, and an axial flux …

Design And Analysis Of Long-Stroke Planar Switched Reluctance Motor For Positioning Applications, Su-Dan Huang, Guang-Zhong Cao, Yeping Peng, Chao Wu, Deliang Liang, Jiangbiao He

Electrical and Computer Engineering Faculty Publications

This paper presents the design, control, and experimental performance evaluation of a long-stroke planar switched reluctance motor (PSRM) for positioning applications. Based on comprehensive consideration of the electromagnetic and mechanical characteristics of the PSRM, a motor design is first developed to reduce the force ripple and deformation. A control scheme with LuGre friction compensation is then proposed to improve the positioning accuracy of the PSRM. Furthermore, this control scheme is proven to ensure the stable motion of the PSRM system. Additionally, the response speed and steady-state error of the PSRM system with this control scheme are theoretically analyzed. Finally, the …

Weld Penetration Identification Based On Convolutional Neural Network, Chao Li

Theses and Dissertations--Electrical and Computer Engineering

Weld joint penetration determination is the key factor in welding process control area. Not only has it directly affected the weld joint mechanical properties, like fatigue for example. It also requires much of human intelligence, which either complex modeling or rich of welding experience. Therefore, weld penetration status identification has become the obstacle for intelligent welding system. In this dissertation, an innovative method has been proposed to detect the weld joint penetration status using machine-learning algorithms.

A GTAW welding system is firstly built. Project a dot-structured laser pattern onto the weld pool surface during welding process, the reflected laser pattern …