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Articles 136861 - 136890 of 304094

Full-Text Articles in Physical Sciences and Mathematics

A Current Feedback Control Strategy For Parallel-Connected Single-Phase Inverters Using A Third-Order General-Integrator Crossover Cancellation Method, Yuan Huang, An Luo Jan 2016

A Current Feedback Control Strategy For Parallel-Connected Single-Phase Inverters Using A Third-Order General-Integrator Crossover Cancellation Method, Yuan Huang, An Luo

Turkish Journal of Electrical Engineering and Computer Sciences

Virtual impedance is usually introduced to the control system of parallel inverters in order to change the inverter equivalent output impedance and to enhance control accuracy and power sharing. In this paper, a current feedback control strategy using a third-order general-integrator crossover-cancellation method that can be implemented in a virtual impedance loop is proposed. This method consists of 2 parts: a crossover-cancellation feedback network, which achieves the band-pass effect, and a multilevel TOGI-OSG link, which acts as a filter. Compared with the conventional virtual impedance method, the proposed method can avoid derivation of output current, reduce system calculating burden, and …

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Wireless Sensor Network-Based Extension To Knx Home Automation System, Ahmet Burak Gökbayrak, Sermi̇n Kilivan, Semavi̇ Akin, Anil Çelebi̇, Oğuzhan Urhan Jan 2016

Wireless Sensor Network-Based Extension To Knx Home Automation System, Ahmet Burak Gökbayrak, Sermi̇n Kilivan, Semavi̇ Akin, Anil Çelebi̇, Oğuzhan Urhan

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a seamless wireless extension approach to a KNX-based home automation system. The system consists of gateway and switch units specifically designed for this purpose. The gateway acts as the coordinator of the wireless network and a bridge between wireless and KNX networks. Switch units can be operated by a power outlet or battery. With the proposed architecture, it is possible to extend functionality of the KNX to wireless nodes, which consume very low power when they are operated by battery. Experimental results show that a simple yet efficient wireless extension to the KNX system is possible by …

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A Novel Compact Defected Ground Structure And Its Application In Mutual Coupling Reduction Of A Microstrip Antenna, Soroush Veisee, Mahsa Keshavarz Hedayati, Shahrooz Asadi Jan 2016

A Novel Compact Defected Ground Structure And Its Application In Mutual Coupling Reduction Of A Microstrip Antenna, Soroush Veisee, Mahsa Keshavarz Hedayati, Shahrooz Asadi

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel compact T-shape defected ground structure (DGS) is proposed in order to reduce the mutual coupling between elements in a microstrip antenna array structure. The proposed DGS has considerable advantages compared to an H-shaped DGS. As is known, DGS insertion is a common problem in microstrip antenna array structures. However, the proposed T-shaped structure is more compact so it could be suitable for a compact microstrip array antenna. The T-shaped DGS is about 24% more compact than the H-shaped one. However, the most important novelty of our work is reducing mutual coupling both in the E-plane …

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Electric Arc Furnace Power Quality Improvement By Applying A New Digital And Predicted-Based Tsc Control, Mehdi Torabian Esfahani, Behrooz Vahidi Jan 2016

Electric Arc Furnace Power Quality Improvement By Applying A New Digital And Predicted-Based Tsc Control, Mehdi Torabian Esfahani, Behrooz Vahidi

Turkish Journal of Electrical Engineering and Computer Sciences

Static VAR compensators (SVC) can improve some of the power quality (PQ) indices such as voltage flicker, unbalances, and power factors in power systems if properly controlled. Different nonlinear and time-varying loads generate these parameters. One of the great nonlinear loads is the electric arc furnace (EAF), which causes waveform distortions, voltage unbalances, and fluctuations. In this paper, a new digital and prediction-based control for thyristor switched capacitors (TSCs) was proposed to compensate an actual steel industrial plant. The digital control was based on generating adequate synchronous pulses, calculating required suitable susceptance, and measuring correct reactive power. The proposed TSC …

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Adaptive Speed Observer With Disturbance Torque Compensation For Sensorless Induction Motor Drives Using Rt-Lab, Mohan Krishna, Febin Daya Jan 2016

Adaptive Speed Observer With Disturbance Torque Compensation For Sensorless Induction Motor Drives Using Rt-Lab, Mohan Krishna, Febin Daya

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an improved version of the extended Luenberger observer with joint estimation of rotor speed and disturbance torque. The mechanical model of the induction motor is also utilized for the estimation of disturbance torque to add to the robustness of the observer. The estimated disturbance torque is treated as a model disturbance and physically incorporated into the observer state dynamic equation. The dynamic performance and efficacy of the modified observer is tested for variations in external load and inertia coefficient in the mechanical model. The above observer model is first built offline, using MATLAB/Simulink block sets, and simulated. …

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An Integrated Analysis For Sustainable Supply Of Remote Winter Tourist Centers - A Future Concept Case Study, Ajla Merzic, Mustafa Music, Mirsad Rascic, Nijaz Hadzimejlic Jan 2016

An Integrated Analysis For Sustainable Supply Of Remote Winter Tourist Centers - A Future Concept Case Study, Ajla Merzic, Mustafa Music, Mirsad Rascic, Nijaz Hadzimejlic

Turkish Journal of Electrical Engineering and Computer Sciences

In every power system there are consumer areas away from traditional power networks. Existing grid expansion can always be treated as one of the ways of powering them over long transmission and distribution lines. This is often characterized by significant transmission losses, as well as significant investments, depending on the distance and the infrastructure development. On the other hand, there are cases when these consumers are not connected to the power system and use alternative methods of supply. For that matter, possible solutions may use locally available energy sources. In this paper, comparative analyses between independent power supply through particular …

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A Hybrid Search Method Of Wrapper Feature Selection By Chaos Particle Swarm Optimization And Local Search, Mohammad Masoud Javidi, Nasibeh Emami Jan 2016

A Hybrid Search Method Of Wrapper Feature Selection By Chaos Particle Swarm Optimization And Local Search, Mohammad Masoud Javidi, Nasibeh Emami

Turkish Journal of Electrical Engineering and Computer Sciences

Finding a subset of features from a large dataset is a problem that arises in many fields of study. Since the increasing number of features has extended the computational cost of a system, it is necessary to design and implement a system with the least number of features. The purpose of feature selection is to find the best subset of features from the original ones. The result of the best selection is improving the computational cost and the accuracy of the prediction. A large number of algorithms have been proposed for feature subset selection. In this paper, we propose a …

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A Ring Crossover Genetic Algorithm For The Unit Commitment Problem, Syed Basit Ali Bukhari, Aftab Ahmad, Syed Auon Raza, Muhammad Noman Siddique Jan 2016

A Ring Crossover Genetic Algorithm For The Unit Commitment Problem, Syed Basit Ali Bukhari, Aftab Ahmad, Syed Auon Raza, Muhammad Noman Siddique

Turkish Journal of Electrical Engineering and Computer Sciences

The unit commitment problem (UCP) is a nonlinear, mixed-integer, constraint optimization problem and is considered a complex problem in electrical power systems. It is the combination of two interlinked subproblems, namely the generator scheduling problem and the generation allocation problem. In large systems, the UCP turns out to be increasingly complicated due to the large number of possible ON and OFF combinations of units in the power system over a scheduling time horizon. Due to the insufficiency of conventional approaches in handling large systems, numerous metaheuristic techniques are being developed for solving this problem. The genetic algorithm (GA) is one …

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Steady State Analysis Of A Three Phase Indirect Matrix Converter Fed 10 Hp, 220 V, 50 Hz Induction Machine For Efficient Energy Generation, Damian Nnadi, Crescent Omeje Jan 2016

Steady State Analysis Of A Three Phase Indirect Matrix Converter Fed 10 Hp, 220 V, 50 Hz Induction Machine For Efficient Energy Generation, Damian Nnadi, Crescent Omeje

Turkish Journal of Electrical Engineering and Computer Sciences

The matrix converter or pulse width modulated frequency changer, invented in the mid-1980s, is a direct power conversion device that can generate a variable voltage and frequency from a variable input source. Industrially, it is applied in adjustable speed control of induction motor drive, power quality conditioner, and traction applications. The aim of this paper is to evaluate the steady state characteristic behavior of an induction machine in terms of its speed and torque when driven by a three phase indirect matrix converter at reduced harmonics. Similarly, projecting an AC-AC matrix converter that ensures a uniform synchronization in frequency and …

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Control Of A Ternary Voltage Progression Based Cascaded Multilevel Inverter Using Classy Split Multicarrier Pulse Width Modulation, Gayathri Monicka Subarnan, Jamuna Venugopal Jan 2016

Control Of A Ternary Voltage Progression Based Cascaded Multilevel Inverter Using Classy Split Multicarrier Pulse Width Modulation, Gayathri Monicka Subarnan, Jamuna Venugopal

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new hybrid pulse width modulation technique is proposed to enhance the performance of output voltage from a ternary progression based multilevel inverter. For high power applications, the multilevel inverter can appropriately replace the traditional converter without a transformer and the separate DC sources will be indispensable for various renewable energy sources. The classy split switching technique for the multicarrier pulse width modulation technique is adopted and the concept about new topology is presented in this paper. An arm controller has been chosen to implement the modulation due to its superior features, easy software, and hardware design. …

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Time Series Adapted Supervised Fuzzy Discretization: An Application To Ecg Signals, Umut Orhan Jan 2016

Time Series Adapted Supervised Fuzzy Discretization: An Application To Ecg Signals, Umut Orhan

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, a new method called supervised fuzzy discretization (SFD), which can be used without having expertise on data, is proposed for classifying time series datasets. Because an ECG signal has a partially stationary characteristic, its classification process is more difficult than it would be for completely stationary signals. On the other hand, because the method proposed can be used without having expertise on the data, comprehensive data like ECG signals are enough to introduce one such method. To prove the efficacy of the SFD, RR intervals selected from a common ECG database are used in the classification experiments. …

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Optimal Siting And Sizing Of Rapid Charging Station For Electric Vehicles Considering Bangi City Road Network In Malaysia, Mainul Islam, Hussain Shareef, Azah Mohamed Jan 2016

Optimal Siting And Sizing Of Rapid Charging Station For Electric Vehicles Considering Bangi City Road Network In Malaysia, Mainul Islam, Hussain Shareef, Azah Mohamed

Turkish Journal of Electrical Engineering and Computer Sciences

Recently, electric vehicles (EVs) have been seen as a felicitous option towards a less carbon-intensive road transport. The key issue in this system is recharging the EV batteries before they are exhausted. Thus, charging stations (CSs) should be carefully located to make sure EV users can access a CS within their driving range. Considering geographic information and traffic density, this paper proposes an optimization overture for optimal siting and sizing of a rapid CS (RCS). It aims to minimize the daily total cost (which includes the cost of substation energy loss, traveling cost of EVs to the CS, and investment, …

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Selective Harmonics Elimination Pwm With Self-Balancing Dc-Link In Photovoltaic 7-Level Inverter, Khoukha Imarazene, Hachemi Chekireb, El Madjid Berkouk Jan 2016

Selective Harmonics Elimination Pwm With Self-Balancing Dc-Link In Photovoltaic 7-Level Inverter, Khoukha Imarazene, Hachemi Chekireb, El Madjid Berkouk

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new DC-link balancing method for a 7-level inverter fed by a photovoltaic system is proposed. The proposed redundant state technique is associated with selective harmonics elimination (SHE)-PWM instead of space vector (SV)-PWM. The switching angles related to the SHE are computed via the resultant theory method. Moreover, the study of this inverter is carried out on its equivalent matrix model. On the basis of this model, the link between the capacitor voltage, switching states, and load current is established. This allows understanding the switching redundancies' effect on the DC capacitor voltage balance. An algorithm is then …

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Computer Vision-Based Control Of An Autonomous Blimp, Korkut Beki̇roğlu, Mario Sznaier, Constantino Lagoa, Bahram Shafai Jan 2016

Computer Vision-Based Control Of An Autonomous Blimp, Korkut Beki̇roğlu, Mario Sznaier, Constantino Lagoa, Bahram Shafai

Turkish Journal of Electrical Engineering and Computer Sciences

The objective of this study is twofold: to approximate a model of a blimp, and to use this model to develop a setup to track a target with the blimp that is outfitted with a wireless camera and radio-controlled propellers. This article presents a powerful method to track any moving or stationary target with an unmanned aerial vehicle by combining the advantages of the proportional derivative (PD) controller, continuously adaptive mean shift (Camshift) algorithm, and pulse width modulation (PWM) method. As a result, it is demonstrated that a decent approximation of blimp behavior is sufficient when using a mathematical model …

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Vector Control Of A Three-Phase Parallel Connected Two Motor Single Inverter Speed Sensorless Drive, Gunabalan Ramachandran, Subbiah Veerana, Sanjeevikumar Padmanaban Jan 2016

Vector Control Of A Three-Phase Parallel Connected Two Motor Single Inverter Speed Sensorless Drive, Gunabalan Ramachandran, Subbiah Veerana, Sanjeevikumar Padmanaban

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents the performance characteristics of two induction motors of the same parameters and ratings connected in parallel and fed by a single inverter. A nature observer is employed to estimate the rotor speeds and rotor fluxes of both induction motors. It also estimates the load torques of both the motors by load torque adaptation. Under unbalanced load conditions, the speed difference between the two induction motors is reduced by considering the average and differential motor parameters and currents. Mean rotor flux is maintained constant by a rotor flux control scheme and the estimation of rotor angle is carried …

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Fuzzy Based Design Of Digital Iir Filter Using Etlbo, Damanpreet Singh, Jaspreet Singh Dhillon Jan 2016

Fuzzy Based Design Of Digital Iir Filter Using Etlbo, Damanpreet Singh, Jaspreet Singh Dhillon

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a population-based robust enhanced teaching--learning-based optimization (ETLBO) algorithm with reduced computational effort and high consistency is applied to design stable digital infinite-impulse response (IIR) filters in a multiobjective framework. Furthermore, a decision-making methodology based on fuzzy set theory is applied to handle nonlinear and multimodal design problems of the IIR digital filter. The original teaching--learning-based optimization (TLBO) algorithm has been remodeled by merging the concepts of opposition-based learning and migration for the selection of good candidates and to maintain diversity, respectively. A multiobjective IIR digital filter design problem takes into consideration magnitude and phase response of the …

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Determination Of The Striking Distance Of A Lightning Rod Using Finite Element Analysis, Ab Halim Abu Bakar, Alyaa Zainal Abidin, Hazlee Illias, Hazlie Mokhlis, Syahirah Abd Halim, Nor Hidayah Nor Hassan, Chia Kwang Tan Jan 2016

Determination Of The Striking Distance Of A Lightning Rod Using Finite Element Analysis, Ab Halim Abu Bakar, Alyaa Zainal Abidin, Hazlee Illias, Hazlie Mokhlis, Syahirah Abd Halim, Nor Hidayah Nor Hassan, Chia Kwang Tan

Turkish Journal of Electrical Engineering and Computer Sciences

The problems related to electromagnetic waves transmitted by lightning strikes can be studied through physical lightning models based on laboratory results. The main concern of these models is determining the striking distance between the leader tip and the lightning rod during lightning occurrences. The striking distance is a significant factor in designing the lightning protection system. However, models using finite element analysis (FEA) for this purpose are less likely to be found in the literature. Therefore, in this work, a geometry model of a lightning rod and leader was developed using available FEA software. The model was used to determine …

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Performance Comparison Of Adaptive Digital Predistortion Algorithms Using Adaptation Time For Mobile Wimax Power Amplifier Applications, Ji-Yeon Kim, Jong-Heon Kim Jan 2016

Performance Comparison Of Adaptive Digital Predistortion Algorithms Using Adaptation Time For Mobile Wimax Power Amplifier Applications, Ji-Yeon Kim, Jong-Heon Kim

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we propose that adaptation time be considered a parameter for evaluating the performance of digital filter algorithms in adaptive digital predistorted high-power amplifiers. An adaptive predistorted high-power amplifier with an average power of 37.5 dBm was designed and fabricated for mobile worldwide interoperability for microwave access (WiMAX) test signals. For performance comparisons using adaptation time, several effective algorithms (such as the least-mean-squares (LMS), recursive-least-squares (RLS), and affine projection (AP) algorithms) were implemented. According to the experimental results, the RLS and AP algorithms achieved a similar linearity improvement of 11 dBr. However, the AP algorithm had the advantage …

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Energy-Aware Stochastic Scheduling Model With Precedence Constraints On Dvfs-Enabled Processors, Mohammad Sajid, Zahid Raza Jan 2016

Energy-Aware Stochastic Scheduling Model With Precedence Constraints On Dvfs-Enabled Processors, Mohammad Sajid, Zahid Raza

Turkish Journal of Electrical Engineering and Computer Sciences

The stochastic scheduling of precedence-constrained jobs on a heterogeneous processor is a challenging problem that requires solutions with one or more optimized QoS parameters. In this work, an energy-aware stochastic algorithm is proposed to schedule the batch of precedence-constrained jobs on heterogeneous DVFS-enabled processors with the objective of optimizing turnaround time and energy consumption. The processing time of tasks in all jobs and their precedence-constraint times are governed by independent probability distributions. The performance of the proposed stochastic algorithm is compared with SHEFT and ECS based on randomly generated batches of different sizes. The experimental study reveals that the proposed …

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Assessment Of The Maximum Loadability Point Of A Power System After Third Zone Of Distance Relay Corrective Actions, Zahra Moravej, Sajad Bagheri Jan 2016

Assessment Of The Maximum Loadability Point Of A Power System After Third Zone Of Distance Relay Corrective Actions, Zahra Moravej, Sajad Bagheri

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, the operation of a system and distance relay is improved during voltage instability by using an improved strategy. After detecting the voltage instability, the third zone is blocked. However, the system is prone to voltage collapse. Shunt capacitor compensation and a load shedding scheme can be used to protect the system from voltage collapse conditions. Load shedding plans can be performed based on a reduction in the power flow in the line where the relay is located. The reason is that the minimum eigenvalue of the load flow Jacobian (reduced and unreduced Jacobians) is increased and the …

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Evaluation Of Hearing Loss Simulation Using A Speech Intelligibility Index, Umut Ariöz, Banu Günel Jan 2016

Evaluation Of Hearing Loss Simulation Using A Speech Intelligibility Index, Umut Ariöz, Banu Günel

Turkish Journal of Electrical Engineering and Computer Sciences

Hearing loss simulation (HLS) is a useful tool for hearing studies, since finding large numbers of hearing-impaired volunteers with various levels of hearing loss is usually a problem. Correct simulation of the hearing impaired ear should take into account different suprathreshold effects, such as reduced frequency selectivity, reduced audibility, and loudness recruitment. Although these effects can be implemented using various algorithms, so far they have not been evaluated in detail taking into account subject dependency, effect of noisy environment, and phonetic characteristics of test words. In this study, for the purpose of evaluating the HLS, a speech intelligibility index (SII) …

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High Photoresponse From Solution Processed Conventional And Inverted Ultraviolet Photodetectors, Görkem Memi̇şoğlu, Canan Varlikli Jan 2016

High Photoresponse From Solution Processed Conventional And Inverted Ultraviolet Photodetectors, Görkem Memi̇şoğlu, Canan Varlikli

Turkish Journal of Electrical Engineering and Computer Sciences

The optical and electrical properties of conventional and inverted type ultraviolet photodetectors (UVPDs) with active layers of poly(9,9-dioctylfluorenyl-2,7-ylenethynylene (PFE), $N$,$N'$-bis-$n$-butyl-1,4,5,8-naphthalenediimide (BNDI), and zincoxide (ZnO) are introduced. Optimized devices showed high photoresponse, external quantum efficiency (EQE), and detectivity (D*) values. Under 365 nm 1 mW/cm$^{2}$, the conventional device (ITO/PEDOT:PSS/[(PFE:BNDI) (3:1):8 wt% ZnO]/Al) and the inverted device (ITO/[(PFE:BNDI)(3:1):8 wt% ZnO]/Au) gave photoresponsivities of 515 mA/W and 316 mA/W, D* of 1.12 $\times$ 10$^{14 }$Jones and 0.71 $\times$ 10$^{14 }$Jones, and EQE of 174% and 107%, respectively. Annealing the devices at polymer's glass transition temperature (T$_{g}$ 60 $^{\circ}$ C), enhanced these values to …

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A Generalized Algorithm For Space Vector Modulation In Multilevel Inverters, Erkan Meşe Jan 2016

A Generalized Algorithm For Space Vector Modulation In Multilevel Inverters, Erkan Meşe

Turkish Journal of Electrical Engineering and Computer Sciences

This paper proposes a new space vector pulse width modulation (SVPWM) algorithm for multilevel inverters that achieves a minimum number of switch state changes in one sampling cycle in order to reduce switching losses. The algorithm can be implemented with minimum computational burden and it does not require any look-up tables. The essence of the technique is to exploit the redundancy of switching functions in the implementation of the voltage vectors and dividing the entire vector space into three sectors in which switching functions have some common features. Careful observations showed that these common features lend themselves to be expressed …

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A Novel Voltage Control Strategy In Collaboration With Information Technology Domains Through The Holonic Architecture, Javad Ansari, Mehdi Ghazavi Dozein, Ahad Kazemi Jan 2016

A Novel Voltage Control Strategy In Collaboration With Information Technology Domains Through The Holonic Architecture, Javad Ansari, Mehdi Ghazavi Dozein, Ahad Kazemi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a novel framework for voltage control based on holonic architecture, with a priority action of local controllers. The proposed architecture is a hierarchical distributed structure in which two various information technology domains called the energy management system holon and flexible AC transmission system holon are defined. In the proposed structure, a dynamic reconfiguring method for holons is used to reduce the time of corrective actions in the case of emergencies.

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Keyframe-Based Video Mosaicing For Historical Ottoman Documents, Edi̇z Şaykol Jan 2016

Keyframe-Based Video Mosaicing For Historical Ottoman Documents, Edi̇z Şaykol

Turkish Journal of Electrical Engineering and Computer Sciences

Image mosaicing is a trendy research area in computer vision in recent years. Instead of images, video frames can be mosaiced to form a larger aggregate. In both cases, merging computations generally depend on the common parts in consecutive images, which are called overlapping regions. The presence of mobile devices with a camera provides higher image and video acquisition; hence video mosaicing techniques can be utilized to digitize and to create high resolution historical document images for later use in browsing and retrieval systems. Here, we present a technique to create high resolution images of historical Ottoman documents from video. …

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A High Performance Ceramic-Polymer Separator For Lithium Batteries, Jitendra Kumar, Padmakar Kichambare, Amarendra K. Rai, Rabi Bhattacharya, Stanley J. Rodrigues, Guru Subramanyam Jan 2016

A High Performance Ceramic-Polymer Separator For Lithium Batteries, Jitendra Kumar, Padmakar Kichambare, Amarendra K. Rai, Rabi Bhattacharya, Stanley J. Rodrigues, Guru Subramanyam

Electrical and Computer Engineering Faculty Publications

A three-layered (ceramic-polymer-ceramic) hybrid separator was prepared by coating ceramic electrolyte [lithium aluminum germanium phosphate (LAGP)] over both sides of polyethylene (PE) polymer membrane using electron beam physical vapor deposition (EB-PVD) technique. Ionic conductivities of membranes were evaluated after soaking PE and LAGP/PE/LAGP membranes in a 1 Molar (1M) lithium hexafluroarsenate (LiAsF6) electrolyte in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) in volume ratio (1:1:1). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were employed to evaluate morphology and structure of the separators before and after cycling performance tests to better understand structure-property correlation. …

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Human Shields And Redistribution Of Prey Species Complicate The Utility Of Protected Areas As Ecological Baselines, Wesley Sarmento Jan 2016

Human Shields And Redistribution Of Prey Species Complicate The Utility Of Protected Areas As Ecological Baselines, Wesley Sarmento

Graduate Student Theses, Dissertations, & Professional Papers

A key goal of protected areas is the conservation of biodiversity, an aim that garners increasing public support through positive experiences. Increasing visitation, however, can come at the cost of reduced ecological integrity. A fundamental conundrum is that if parks are to serve as our most pristine places, then we must understand how our presence alters species interactions. Species redistributing closer to people is of growing management concern both in and out of national parks because of 1) human safety, 2) animal health, and 3) ecological consequences. Across parks drivers of distributional change are often dissimilar, and include movement to …

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Investigating The Influence Of Offline Friendship On Twitter Networking Behaviors, Young Soo Kim, Felicia Natali, Feida Zhu, Ee-Peng Lim Jan 2016

Investigating The Influence Of Offline Friendship On Twitter Networking Behaviors, Young Soo Kim, Felicia Natali, Feida Zhu, Ee-Peng Lim

Research Collection School Of Computing and Information Systems

We investigate the influence of offline friendship in three specific areas of Twitter networking behaviors: (a) network structure, (b) Twitter content and (c) interaction on Twitter. We observe some interesting findings through the empirical analysis of 2193 pairs of users who are online friends. When these pairs of users know each other offline, they are more likely to (1) respond to the online gesture of friendship from their friend, (2) share mutual online friends, (3) distribute and gather information in their friend’s Twitter network, (4) pay attention to their friend’s tweets, (5) post tweets that might be of interest to …

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Land Cover Mapping And Change Analysis At The Tensleep Preserve In Wyoming, Tyler Richard Grupa Jan 2016

Land Cover Mapping And Change Analysis At The Tensleep Preserve In Wyoming, Tyler Richard Grupa

All Graduate Theses, Dissertations, and Other Capstone Projects

Mapping land cover and land cover change are important, especially for land managers who protect natural lands and generate restoration projects. Accurate land cover assessment of rangelands can be difficult because the spectral difference between plant species may be minimal. The goal of this research is to map the land cover in the Tensleep Preserve and highlight change that has occurred over the past twenty-three years using the Feature Analyst extension. The land cover change map will highlight significant changes and Feature Analyst will accurately identify different land covers using historical aerial photographs and ground truthing data collected in 2013. …

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Early Detection Of Mountain Pine Beetle Damage In Ponderosa Pine Forests Of The Black Hills Using Hyperspectral And Worldview-2 Data, Kyle Edward Mullen Jan 2016

Early Detection Of Mountain Pine Beetle Damage In Ponderosa Pine Forests Of The Black Hills Using Hyperspectral And Worldview-2 Data, Kyle Edward Mullen

All Graduate Theses, Dissertations, and Other Capstone Projects

A leading cause for mortality in the pine forests of western North America, the mountain pine beetle, has impacted over 400,000 acres of ponderosa pine forest in the Black Hills of South Dakota since 1996. Methods aimed at earlier detection, prior to visual manifestation of a mountain pine beetle damage in the tree crown, have not been successful because of the overlap and variability of spectral response between the initial stages of attack (green-attacked) and non-attacked tree crowns. Needle-level reflectance spectra was measured from green-attack and non-attack ponderosa pine trees in early spring following an infestation and analyzed using a …

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