Physical Sciences and Mathematics Commons^™

Analysis And Design Of Non-Hermitian Optical Systems, Ali Kazemi Jahromi

Electronic Theses and Dissertations

From a very general perspective, optical devices can be viewed as constructions based on the spatial engineering of the optical index of refraction. Sculpting the real part of the refractive index produces the wide variety of known passive optical devices, such as waveguides, resonators, gratings, among a plethora of other possibilities for managing the transport of light. Less attention has been directed to engineering the imaginary part of the refractive index – that is responsible for optical gain and absorption – in conjunction with the real part of the refractive index. Optical gain is the building block of amplifiers and …

Ssaw: A New Sequence Similarity Analysis Method Based On The Stationary Discrete Wavelet Transform, Jie Lin, Donald Adjeroh, Bing-Hua Jiang, Yue Jiang

Faculty & Staff Scholarship

Background: Alignment-free sequence similarity analysis methods often lead to significant savings in computational time over alignment-based counterparts.

Results: Anewalignment-freesequencesimilarityanalysismethod,calledSSAWisproposed.SSAWstandsfor Sequence Similarity Analysis using the Stationary Discrete Wavelet Transform (SDWT). It extracts k-mers from a sequence, then maps each k-mer to a complex number field. Then, the series of complex numbers formed are transformed into feature vectors using the stationary discrete wavelet transform. After these steps, the original sequence is turned into a feature vector with numeric values, which can then be used for clustering and/or classification.

Conclusions: Usingtwodifferenttypesofapplications,namely,clusteringandclassification,wecomparedSSAW against the the-state-of-the-art alignment free sequence analysis methods. SSAW demonstrates competitive or …

Introduction: Metrics, Modeling And Simulation For Cyber Physical Systems, Barry Ezell, Luanne Burns

VMASC Publications

[Introduction] In recent years, there has been a massive increase in cyber crime. Cyber breeches have become ubiquitous. The US government is attempting to adapt through legislation and policy. For instance, business in the defense industrial base must be in compliance of NIST 80-71 by 31 December 2017. Insurance companies as well are beginning to build actuaries on cyber risk. Along with NIST, there are many cyber frameworks that exist, each with their own following. Recently, companies have sought mapping from one framework to another but this is imperfect solution because some frameworks are exclusively technical control measures with very …

Resource Optimization In Wireless Sensor Networks For An Improved Field Coverage And Cooperative Target Tracking, Husam Sweidan

Dissertations, Master's Theses and Master's Reports

There are various challenges that face a wireless sensor network (WSN) that mainly originate from the limited resources a sensor node usually has. A sensor node often relies on a battery as a power supply which, due to its limited capacity, tends to shorten the life-time of the node and the network as a whole. Other challenges arise from the limited capabilities of the sensors/actuators a node is equipped with, leading to complication like a poor coverage of the event, or limited mobility in the environment. This dissertation deals with the coverage problem as well as the limited power and …

Improving Time-Of-Flight And Other Depth Images: Super-Resolution And Denoising Using Variational Methods, Salvador Canales Andrade

Open Access Theses & Dissertations

Depth information is a new important source of perception for machines, which allow them to have a better representation of the surroundings. The depth information provides a more precise map of the location of every object and surfaces in a space of interest in comparison with conventional cameras. Time of flight (ToF) cameras provide one of the techniques to acquire depth maps, however they produce low spatial resolution and noisy maps. This research proposes a framework to enhance and up-scale depth maps by using two different regularization terms: Total Generalized Variation (TGV) and Total Generalized Variation with a Structure Tensor …

A Novel Multistage System For The Detection And Removal Of Pectoral Muscles Inmammograms, İdi̇l Işikli Esener, Semi̇h Ergi̇n, Tolga Yüksel

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel multistage scheme for pectoral muscle removal from mammography images is proposed, and the performance of this system is verified using the publicly available Mammographic Image Analysis Society digital mammogram database. This database is composed of mediolateral oblique mammography images including three different tissue types (fatty, fatty-glandular, and dense-glandular) with three health status types (normal, benign cancer, and malignant cancer). In the implementation of the proposed system, a mammography image is first preprocessed by performing noise reduction background removal followed by artifact suppression processes. Then a presegmentation procedure is applied using region growing and line fitting …

Automatic Detection Of The Respiratory Cycle From Recorded, Single-Channel Sounds From Lungs, Seli̇m Aras, Mehmet Öztürk, Ali̇ Gangal

Turkish Journal of Electrical Engineering and Computer Sciences

Listening to the sounds made by the lungs is a long-standing method that is still used to diagnose lung diseases. Many studies have been conducted on the automatic recognition of recorded sounds from the lungs. However, in these studies, respiratory cycles, i.e. inhalations followed by exhalations, were either monitored manually or by using multichannel signals of the sounds made by the lungs. In order to recognize sounds made by the lungs automatically, one must first use these sounds to determine the respiratory cycles. Our previous study was the first study presented in the literature in which the boundaries of respiratory …

Performance Analysis Of Hamming Code For Wsn-Based Smart Grid Applications, Meli̇ke Yi̇ği̇t, Vehbi̇ Çağri Güngör, Pinar Bölük

Turkish Journal of Electrical Engineering and Computer Sciences

Many methods have been employed to detect, compare, and correct errors to increase communication reliability and efficiency in wireless sensor networks (WSNs). However, to the best of our knowledge, no existing study has compared the performance of error control codes by using different modulation techniques in a smart grid communication environment when multichannel scheduling is used. This paper presents a detailed performance evaluation and makes a comparison of different modulation techniques, such as frequency shift keying (FSK), differential phase shift keying (DPSK), binary phase shift keying (BPSK), and offset quadrature phase-shift keying (OQPSK), using Hamming codes in a 500-kV line-of-sight …

Improving The Incremental Conductance Algorithm For Two-Stage Grid-Connectedphotovoltaic Systems, Mehmet Ali̇ Özçeli̇k, Ahmet Serdar Yilmaz

Turkish Journal of Electrical Engineering and Computer Sciences

Efficiency of solar photovoltaic generation plants depends not only on internal operational conditions but also on external atmospheric conditions. Total efficiency is in uenced by various weather conditions such as cloudiness, temperature, and irradiation. In order to generate maximum energy, photovoltaic (PV) arrays should be operated at their maximum power point (MPP), varying external factors like partial shading and surface temperature and amount of radiation coming from the sun. In modern PV systems, maximum power point trackers (MPPTs) have been used in order to reach the MPP, changing with the factors given above. MPPT units are implemented to control DC-DC …

Damping Wide-Area Oscillations In Power Systems: A Model Predictive Controldesign, Emrah Biyik, Munir Husein

Turkish Journal of Electrical Engineering and Computer Sciences

Electromechanical oscillations in power systems have been observed ever since synchronous generators were interconnected to provide reliability and higher generation capacity, and they have become a severe threat for the safe and economic operation of modern interconnected power grids. To dampen these oscillations, wide-area damping controllers (WADCs) have been introduced by utilizing wide-area measurement systems and synchronized phasor measurement units. In this paper, we present a systematic approach for designing WADCs using a model predictive control (MPC) technique to damp interarea oscillations in the power system. The MPC controller computes optimal control signals for the excitation system of a remote …

An Efficient Technique Based On Firefly Algorithm For Pilot Design Process In Ofdm-Idma Systems, Necmi̇ Taşpinar, Şaki̇r Şi̇mşi̇r

Turkish Journal of Electrical Engineering and Computer Sciences

Accurate placement of pilot tones has been a crucial task in multicarrier transmission technologies since there is a strong relation between pilot positions and channel estimation performance. Therefore, the firefly algorithm (FA) is proposed for achieving the optimal pilot distribution by optimizing the pilot positions in order to minimize the estimation errors of the least squares algorithm employed in orthogonal frequency division multiplexing-interleave division multiple access (OFDM-IDMA) systems. According to the simulation results, our proposed FA-based pilot optimizer provides a great performance increase in OFDM-IDMA systems by obtaining the most appropriate pilot distribution pattern among the considered pilot placement strategies. …

Prediction Of The Mass Unbalance Of A Variable Speed Induction Motor By Stator Current Multiple Approaches, Abdelkarim Bouras, Slimane Bouras, Samir Kerfali

Turkish Journal of Electrical Engineering and Computer Sciences

Generally, rotor mass unbalance is one of the most probable causes of the majority of degradations suffered by electric drives in an industrial environment (current pumping, rolling problem, misalignment, etc.), especially those with high power and variable speed. This document is an experimental contribution to the reliable detection of mass unbalance and changes in its severity if, by necessity of service, the system is subjected to a speed variation. The implementation of the technical orbits Park, strengthened by the application of the Fourier transforms (FFT, STFT) to the Park vector of the stator current allowed the identification of the unbalance …

Long-Term Multiobject Tracking Using Alternative Correlation Filters, Kemal Batuhan Başkurt, Refi̇k Samet

Turkish Journal of Electrical Engineering and Computer Sciences

We propose a real-time multiobject-tracking approach that is minimally affected by environmental conditions and target appearance change. The aim of the proposed approach is to track any object in a scene, regardless of object type, since tracking all of the objects in a scene is critical and widely used in surveillance applications. Thus, motion detection results are used to initialize the trackers. The proposed object-tracking approach is realized with two types of independent correlation filters estimating location and scale. Alternative correlation filters representing different appearances of the target are also proposed in order to increase the robustness of the approach …

Symbolic Interpretation Of Artificial Neural Networks Using Genetic Algorithms, Dounia Yedjour, Abdelkader Benyettou, Hayat Yedjour

Turkish Journal of Electrical Engineering and Computer Sciences

The knowledge acquired during the learning of artificial neural networks (ANNs) is coded as values in synaptic weights, which makes their interpretations difficult, hence the name of the black box. The aim of this work is to provide a comprehensible interpretation of the ANN's decisions by extracting symbolic rules. We improve the performance of our extraction algorithm by combining the ANN with a genetic algorithm. Misleading rules whose support and confidence values are less than fixed thresholds are removed and, as a result, the comprehensibility is improved. The extracted rules are evaluated and compared with other works. The results show …

Sar Image Time-Series Analysis Framework Using Morphological Operators And Global And Local Information-Based Linear Discriminant Analysis, Ufuk Sakarya, Caner Demi̇rpolat

Turkish Journal of Electrical Engineering and Computer Sciences

Fusion of spectral, spatial, and temporal information is an effective method used in many satellite remote sensing applications. On the other hand, one drawback of this fusion is an increase in complexity. In this paper, we focus on developing a fast and well-performed classification method for agricultural crops using time-series SAR data. In order to achieve this, a novel two-stage approach is proposed. In the first stage, a high-dimensional feature space is obtained using time-series dual-pol SAR data and morphological operators. Spectral, spatial, and temporal information is combined into a single high-dimensional feature space. In the second stage, a dimension …

The Measurement Of Shielding Effectiveness For Small-In-Size Ferrite-Based Flat Materials, İsa Araz

Turkish Journal of Electrical Engineering and Computer Sciences

This work presents the results of our studies on the electromagnetic interference shielding effectiveness of small-in-size samples of ferrite composition microwave absorber prepared by using the ceramic method. The shielding effectiveness measurement was performed using the complex intrinsic parameters of the material. The coaxial holder method with the well-known test technique based on transmission/reflection measurements was used in the experimental setup. Complex intrinsic parameters were measured in the frequency range of 2-18 GHz by using the Nicholson - Ross - Weir (NRW) method with an automated test setup. First, the shielding effectiveness was measured by conventional test method and then …

Extending Co-Citation Using Sections Of Research Articles, Arjumand Yar Khan, Abdul Shahid Khattak, Muhammad Tanvir Afzal

Turkish Journal of Electrical Engineering and Computer Sciences

The excessive amount of digital information has made it crucial to extract the relevant information. This hinders researchers in finding documents pertaining to their research. There exist various state-of-the-art techniques, such as co-citation, bibliographic coupling, and their recent extensions like citation proximity analysis and citation order analysis, that recommend the relevant documents against the posed query. Most of these approaches are statistical in nature and thus can further be extended by incorporating some semantics to enhance the results. In this paper, we present an extension of a co-citation-based technique to identify the most relevant documents to co-cited document(s). The proposed …

Predicting Energy And Water Consumption On Dairy Farms Through Statistical Analysis And Machine-Learning Methods, Philip Shine

Theses

With the abolishment of milking quotas across all European Union member states in April 2015, dairy farmers must adjust their farming practises to minimise milk production costs to adequately prepare for potential periods of reduced revenue. Milk production is an intense energy and water consuming process. Coupled with challenging European greenhouse gas reduction targets and legislation regarding the prevention of groundwater pollution and deterioration, increasing the production of milk in Ireland must be met with the sustainable consumption of on-farm energy and direct water resources, to ensure the future monetary and environmental sustainability of Ireland’s dairy industry. Thus, this body …

Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem, Qian Ma, Keqin Gu, Narges Choubedar

SIUE Faculty Research, Scholarship, and Creative Activity

This article studies the strong stability of scalar difference equations of continuous time in which the delays are sums of a number of independent parameters tau_i, i = 1, 2, . . . ,K. The characteristic quasipolynomial of such an equation is a multilinear function of exp(-tau_i s). It is known that the characteristic quasipolynomial of any difference equation set in the form of one-delayper- scalar-channel (ODPSC) model is also in such a multilinear form. However, it is shown in this article that some multilinear forms of quasipolynomials are not characteristic quasipolynomials of any ODPSC difference equation set. The equivalence …

Interoperable Ocean Observing Using Archetypes: A Use-Case Based Evaluation, Paul Stacey, Damon Berry

Conference papers

This paper presents a use-case based evaluation of the impact of two-level modeling on the automatic federation of ocean observational data. The goal of the work is to increase the interoperability and data quality of aggregated ocean observations to support convenient discovery and consumption by applications. An assessment of the interoperability of served data flows from publicly available ocean observing spatial data infrastructures was performed. Barriers to consumption of existing standards-compliant ocean-observing data streams were examined, including the impact of adherence to agreed data standards. Historical data flows were mapped to a set of archetypes and a backward integration experiment …

Thin-Film Lithium Niobate Photonics For Electro-Optics, Nonlinear Optics, And Quantum Optics On Silicon, Ashutosh Rao

Electronic Theses and Dissertations

Ion-sliced thin-film lithium niobate (LN) compact waveguide technology has facilitated the resurgence of integrated photonics based on lithium niobate. These thin-film LN waveguides offer over an order of magnitude improvement in optical confinement, and about two orders of magnitude reduction in waveguide bending radius, compared to conventional LN waveguides. Harnessing the improved confinement, a variety of miniaturized and efficient photonic devices are demonstrated in this work. First, two types of compact electrooptic modulators are presented – microring modulators, and Mach-Zehnder modulators. Next, two distinct approaches to nonlinear optical frequency converters are implemented – periodically poled lithium niobate, and mode shape …

Analysis Of High Performance Scientific Programming Workflows, Withana Kankanamalage Umayanganie Klaassen

Open Access Theses & Dissertations

Substantial time is spent on building, optimizing and maintaining large-scale software that is run on supercomputers. However, little has been done to utilize overall resources efficiently when it comes to including expensive human resources. The community is beginning to acknowledge that optimizing the hardware performance such as speed and memory bottlenecks contributes less to the overall productivity than does the development lifecycle of high-performance scientific applications. Researchers are beginning to look at overall scientific workflows for high performance computing. Scientific programming productivity is measured by time and effort required to develop, configure, and maintain a simulation experiment and its constituent …

Parallelization And Scalability Analysis Of The \\[1pc] 3d Spatially Variant Lattice Algorithm, Henry Roger Moncada Lopez

Open Access Theses & Dissertations

The purpose of this research is to design a faster implementation of an algorithm to generate 3D spatially variant lattices (SVL) and improve its performance when it is running on a parallel computer system. The algorithm is used to synthesize a SVL for a periodic structure. The algorithm has the ability to spatially vary the unit cell, the orientation of the unit cells, lattice spacing, fill fraction, material composition, and lattice symmetry. The algorithm produces a lattice that is smooth, continuous and free of defects. The lattice spacing remains strikingly uniform even when the lattice is spatially varied. This is …

Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem, Qian Ma, Keqin Gu, Narges Choubedar

SIUE Faculty Research, Scholarship, and Creative Activity

This article studies the strong stability of scalar difference equations of continuous time in which the delays are sums of a number of independent parameters τi, i = 1, 2, . . . , K. The characteristic quasipolynomial of such an equation is a multilinear function of e−τis. It is known that the characteristic quasipolynomial of any difference equation set in the form of one-delay-per-scalar-channel (ODPSC) model is also in such a multilinear form. However, it is shown in this article that some multilinear forms of quasipolynomials are not characteristic quasipolynomials of any ODPSC difference equation set. The equivalence between …

Mode-Locked Laser Based On Large Core Yb3+-Doped Fiber, Fei Jia

Electronic Theses and Dissertations

The thesis reviews principle of laser cavity and gives a general introduction to modelocked laser (MLL). By using Yb3+-doped fiber as gain medium, passive MLL cavity is developed in experiment, aiming to obtain femtosecond pulses with high pump power from 25W to 35W. The gain medium fiber with 65µm core diameter is cleaved with one flat end and another angled. Pump laser with 976nm wavelength is coupled into Yb3+ -doped fiber to excite signal from 1020nm to 1040nm in the core. 9W is threshold for laser setup. After locking all modes, picosecond pulses are output from laser cavity and coupled …

Fiber Optimization For Operation Beyond Transverse Mode Instability Limitations, Joshua Bradford

Electronic Theses and Dissertations

Transverse Mode Instabilities (TMIs) stand as a fundamental limitation to power and brightness scaling in laser systems based upon optical fiber technologies. This work comprises experimental and theoretical investigations into fiber laser design that should minimize the effects of Stimulated Thermal Rayleigh Scattering. Theoretical discussions and simulations focus on how fiber parameters affect transverse mode coupling. These include core geometry optimization, pump geometry optimization, in addition to the effects of HOM content and losses on the TMI threshold. Experimentally, a high-power laser facility is commissioned with beam quality diagnostics to quantify the thresholds of the onset of modal interferences and …

Research Of Sustainable Jet Fuel Production Using Microbes, Rajee Olaganathan

Publications

Global climate change, coupled with rapidly increasing oil prices and energy demand around the world, has paved a way for intense research in the biofuel sector. Stakeholders in the aviation industry have started to focus on bio-jet fuel. Bio-jet fuel is regarded as a sustainable solution to greenhouse gas emissions and energy demand. This paper provides a brief review of the biofuel production technologies, the role of bacteria in producing hydrocarbons and the recent advancements in microbial engineering to enhance the biofuel production. Finally, this paper concludes by highlighting the challenges and future research implications in bio-jet fuel production.

A Generalized Detection System To Detect Distributed Denial Of Service Attacks And Flash Events For Information Theory Metrics, Sunny Behal, Krishan Kumar, Monika Sachdeva

Turkish Journal of Electrical Engineering and Computer Sciences

Distributed denial of service (DDoS) attacks pose a severe threat to extensively used web-based services and applications. Many detection approaches have been proposed in the literature, but ensuring the security and availability of data, resources, and services to end users remains an ongoing research challenge. Nowadays, the traffic volume of legitimate users has also increased manifold. A flash event (FE) is a high-rate legitimate traffic situation wherein millions of legitimate users start accessing a particular network resource, such as a web server, simultaneously. The detection of DDoS attacks becomes more challenging when DDoS attacks are launched during behaviorally similar FEs. …

Improved Transient Response Capacitor Less Low Dropout Regulator Employing Adaptive Bias And Bulk Modulation, Suresh Alapati, Sreehari Rao Patri

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a low quiescent current, fast settling time, and adaptively biased capacitor less low-dropout (LDO) regulator. The topology involves a segmented pass transistor with bulk modulation and adaptively biased current control stages to improve the transient performance. The bulk modulation of the pass transistor assists in fast settling of the output voltage. The frequency compensation makes the LDO voltage regulator stable adaptively over load current transitions. In addition, the biasing stage is designed such that it adapts to the load transitions while consuming the quiescent current abstemiously. This arrangement further improves settling time to be within 1 µs …

Q-Axis Current Perturbation Based Active Islanding Detection For Converter Interfaced Distributed Generators, Suman Murugesan, Venkatakirthiga Murali

Turkish Journal of Electrical Engineering and Computer Sciences

Thanks to the incessant developments in technology towards extracting electric power from renewable energy resources, incorporation of distributed generators has been gaining great importance in recent years. The key expedients for such power generation include reduction in power loss and improvement in the power quality and reliability. In spite of the numerous advantages, it is mandatory to ascertain the island formation and shut down the distributed generators (DGs) during an unplanned islanding. An analyzing technique subsequent to an active islanding detection technique is proposed in this work for faster and accurate detection of island formation. The proposed technique is investigated …