Engineering Commons^™

Minimizing Reverse Current Flow Due To Distributed Generation Via Optimal Network Reconfiguration, Jasrul Jamani Jamian, Muhammad Mohsin Aman, Muhammad Ariff Baharuddin, Ahmad Safawi Mokhtar, Mohd Noor Abdullah

Turkish Journal of Electrical Engineering and Computer Sciences

Distributed generation (DG) is widely used to minimize total power losses in distribution networks. However, one of the problems of DG in a grid system is reverse current flow (RCF), which is when the DG output becomes greater than the connected load. Therefore, this paper proposes a multiobjective artificial bee colony (MOABC) algorithm to determine the optimal network reconfiguration for reducing total RCF in DG. The proposed algorithm is tested on 33-bus radial distribution systems in two different scenarios, i.e. base case and with 50% load. The proposed technique can reduce reverse current by up to 93%; however, the total …

Multiclass Semantic Segmentation Of Faces Using Crfs, Khalil Khan, Nasir Ahmad, Khalil Ullah, Irfanud Din

Turkish Journal of Electrical Engineering and Computer Sciences

Multiclass semantic image segmentation is widely used in a variety of computer vision tasks, such as object segmentation and complex scene understanding. As it decomposes an image into semantically relevant regions, it can be applied in segmentation of face images. In this paper, an algorithm based on multiclass semantic segmentation of faces is proposed using conditional random fields. In the proposed model, each node corresponds to a superpixel, while the neighboring superpixels are connected to nodes through edges. Unlike previous approaches, which rely on three or four classes, the label set is extended here to six classes, i.e. hair, eyes, …

Dynamic Security Enhancement Of Power Systems Using Mean-Variance Mapping Optimization, Cavi̇t Fati̇h Küçüktezcan, Veysel Murat İstemi̇han Genç

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a preventive control action that involves both generation rescheduling and load curtailment is proposed for enhancing the dynamic security of large interconnected power systems. The control action is formulated as a security-constrained optimization problem that is solved by mean-variance mapping optimization (MVMO) integrated with a self-adaptive penalization technique and artificial neural networks to develop a fast and effective methodology. The proposed methodology is applied to a 16-generator 68-bus test system to solve the security-constrained optimization problem with both continuous and discrete decision variables. To find a proper and cost-effective solution for the control actions within an acceptable …

A New Segmentation Method Of Cerebral Mri Images Based On The Fuzzy C-Means Algorithm, Mohamed Zaki Abderrezak, Mouatez Billah Chibane, Karim Mansour

Turkish Journal of Electrical Engineering and Computer Sciences

The aim of this work is to present a new method for cerebral MRI image segmentation based on modification of the fuzzy c-means (FCM) algorithm. We used local and nonlocal information distance in the initial function of the robust FCM model. The obtained results of the classification of MRI images showed the effectiveness of the suggested model. Calculation of the similarity index confirms that our method is well adapted to MRI images even in the presence of noise.

Assessment Of Disordered Voices Based On An Optimized Glottal Source Model, Mounir Boudjerda, Abdellah Kacha

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a method for the assessment of disordered voices is proposed. A feature named mean opening quotient (MOQ) obtained from the glottal source estimation is used as an acoustic cue to summarize the degree of severity of the voice disorder. The analysis method uses the empirical mode decomposition algorithm to estimate the glottal source excitation signal from the speech signal. The logarithm of the magnitude spectrum of the speech signal is decomposed into oscillatory modes, called intrinsic mode functions, that are clustered into two classes, the spectral envelope and the harmonic component. The exploitation of the phase information …

Distinct Degradation Processes In Zno Varistors: Reliability Analysis And Modeling With Accelerated Ac Tests, Hadi Yadavari, Mustafa Altun

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, we investigate different degradation mechanisms of zinc oxide (ZnO) varistors. We propose a model that shows how Vv (defined as DC varistor voltage when a 1-mA DC current is applied) changes with time for different stress levels. For this purpose, accelerated degradation tests are applied for different AC current levels and voltage values are then measured. Different from the common practice in the literature that considers degradation with only decreasing Vv values, we demonstrate either an increasing or a decreasing trend in the Vv parameter. The tests show a decreasing trend in Vv for current levels above …

A Particle Swarm Optimization And Block-Svd-Based Watermarking For Digital Images, Falgun Thakkar, Vinay Kumar Srivastava

Turkish Journal of Electrical Engineering and Computer Sciences

The major issues in most watermarking schemes are security, reliability, and robustness against attacks. To achieve these objectives in a watermarking algorithm, the selection of a scale factor to embed the watermark into the host image is a challenging problem. In this paper, a block singular value decomposition (SVD)-based reliable, robust, secure, and fast watermarking scheme is proposed that uses particle swarm optimization (PSO) in the selection of the scale factor. SVD is applied here on the nonoverlapping blocks of LL wavelet subbands. Selected singular values of these blocks are modified with the pixel values of the watermark image. Selected …

Fpga-Based Soc For Hardware Implementation Of A Local Histogram-Based Video Shot Detector, Abdessalem Ben Abdelali, Mohamed Nidhal Krifa, Abdellatif Mtibaa

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, we present a video application example and its implementation in a reconfigurable system-on-chip (SOC) platform. The proposed platform employs the benefits of field programmable gate array (FPGA) technology. A prototype based on a Xilinx Virtex-5 FPGA is developed. The application includes a video shot boundary detection module based on the local histogram (LH) technique. Diverse hardware module versions corresponding to different quantization levels and architectural solutions for an LH-based shot detection system are presented. The developed modules have different hardware resource occupations and can be used in a dynamic way to allow flexible management of the target …

Optimal Fusion Of Multiple Gnss Signals Against Spoofing Sources, Selçuk Şahi̇n, Abedallatif Baba, Tolga Sönmez

Turkish Journal of Electrical Engineering and Computer Sciences

Electronic attacks such as spoofing are becoming an increasing threat for satellite-based navigation receivers. The aim of this paper is to develop a preventive method against such electronic attacks. In our scheme, the localization system uses four different Global Navigation Satellite Systems (GNSSs): GPS, Galileo, GLONASS, and Compass. The signals received from these satellite systems will be fused inferentially and will be tracked according to a linear model. The linear model that we developed is solved with a Kalman filter and simulated under different scenarios. When a discrepancy is detected in the output of one of the GNSS receivers due …

Disk Scheduling With Shortest Cumulative Access Time First Algorithms, Nai̇l Akar, Çağlar Tunç, Mark Gaertner, Fati̇h Erden

Turkish Journal of Electrical Engineering and Computer Sciences

A new class of scheduling algorithms is proposed for disk drive scheduling. As opposed to choosing the request with the shortest access time in conventional shortest access time first (SATF) algorithms, we choose an ordered sequence of pending I/O requests at the scheduling instant with the shortest cumulative access time. Additionally, we introduce flexibility for forthcoming requests to alter the chosen sequence. Simulation results are provided to validate the effectiveness of the proposed disk scheduler. Throughput gains of 3% and above are shown to be attainable, although this occurs at the expense of increased computational complexity.

Eliminating The Illusion Of Learning From Engineering Courses, Jason Weaver

Faculty Publications

This paper describes the efforts of the author to incorporate tools into an undergraduate engineering course to help facilitate better learning and assess proficiency more effectively by avoiding the illusion of learning. Several techniques are used, including suggestions from the recent book Make It Stick by Brown, Roediger, and McDaniel. Student feedback and instructor observations are discussed, and future recommendations for the course are given

Sensitivity Analysis For Justification Of Utilising Special Purpose Machine Tools In The Presence Of Uncertain Parameters, Ana Vafadar, Kevin Hayward, Majid Tolouei-Rad

Research outputs 2014 to 2021

Decision-makers in manufacturing area frequently face machine tool selection problem under uncertainty due to competitive market changes. Special purpose machines (SPMs), a relatively new class of reconfigurable machine tools, are used to react quickly to changes. Justification of utilising these machines vs. other machine tools requires a technique to investigate the sources of uncertainties. In this work, sensitivity analysis is utilised to investigate the sources of these uncertainties and errors which may reveal new insights for evaluating a machine tool. An illustrative example is provided to show the sensitivity of parameters on the economic performance of SPMs compared to the …

Fiber Bragg Grating Sensors For Mainstream Industrial Processes, Gary Allwood, Graham Wild, Steven Hinkley

Research outputs 2014 to 2021

This paper reviews fiber Bragg grating sensing technology with respect to its use in mainstream industrial process applications. A review of the various types of sensors that have been developed for industries such as power generation, water treatment and services, mining, and the oil and gas sector has been performed. A market overview is reported as well as a discussion of some of the factors limiting their penetration into these markets. Furthermore, the author’s make recommendations for future work that would potentially provide significant opportunity for the advancement of fiber Bragg grating sensor networks in these mainstream industries.

An Investigation Into Spike-Based Neuromorphic Approaches For Artificial Olfactory Systems, Anup Vanarse, Adam Osseiran, Alexander Rassau

Research outputs 2014 to 2021

The implementation of neuromorphic methods has delivered promising results for vision and auditory sensors. These methods focus on mimicking the neuro-biological architecture to generate and process spike-based information with minimal power consumption. With increasing interest in developing low-power and robust chemical sensors, the application of neuromorphic engineering concepts for electronic noses has provided an impetus for research focusing on improving these instruments. While conventional e-noses apply computationally expensive and power-consuming data-processing strategies, neuromorphic olfactory sensors implement the biological olfaction principles found in humans and insects to simplify the handling of multivariate sensory data by generating and processing spike-based information. Over …

Resistivity Profiles Of Perth Soil In Australia In Leak-Detection Test, Lopa M. Pandey, Sanjay K. Shukla, Daryoush Habibi

Research outputs 2014 to 2021

The use of a suitable leak-detection system for the prevention and mitigation of pollution due to lining system failures is integral to the proper management of landfill facilities. This paper briefly summarises various methods of leak detection that are currently being practised. The details of a newly developed leak-detection technique are also presented. The tests were conducted to evaluate the performance of the new technique by use of controlled leakage. The resulting resistivity profiles for Perth soil in Australia were obtained at 10 min. This method is found to be effective in detecting and locating liner leakage issues within 30 …

Gradient In Microstructure And Mechanical Property Of Selective Laser Melted Alsi10mg, Yujing Liu, Zeng Qian Liu, Y Jiang, G.W Wang, Yang Yang, Laichang Zhang

Research outputs 2014 to 2021

It is known that metal parts can be made stronger, tougher and better wear resistance by introducing gradient microstructure. This work reports the cooling rate of melt pool induced discrepancy in microstructural gradient and element distribution during selective laser melting (SLM), thereby resulting in decrease in microhardness and wear resistance from surface to inside with a range of ∼100 μm of SLM- manufactured AlSi10Mg alloy. The cooling rate in the top surface of melt pool reaches ∼ 1.44 × 10⁶ K/s, which is much higher than that at the bottom ( ≤ 1 × 10³ K/s). Such a …

Enhanced Corrosion And Wear Resistance Properties Of Carbon Fiber Reinforced Ni-Based Composite Coating By Laser Cladding, Jianbo Lei, Chuan Shi, Shenfeng Zhou, Zhenjie Gu, Laichang Zhang

Research outputs 2014 to 2021

To enhance the wear resistance and corrosion resistance of Ni-based coatings, carbon fibers reinforced nickel-based composite coatings (CFs/Ni) were fabricated on the surface of 1Cr13 stainless steel by laser cladding (LC). The microstructure characteristics, microhardness, wear and corrosion performances of the composite coatings were investigated. The results show that CFs can effectively improve the corrosion and wear resistances of Ni-based coatings. With increasing laser scanning speed, the morphology of CFs in composite coatings is more integral and the corrosion and wear resistances of the composite coatings are improved. Especially, when laser scanning speed is increased to 8 mm/s, the average …

Drilling Reconfigurable Machine Tool Selection And Process Parameters Optimization As A Function Of Product Demand, Ana Vafadar, Kevin Hayward, Majid Tolouei-Rad

Research outputs 2014 to 2021

Special purpose machines (SPMs) are customized machine tools that perform specific machining operations in a variety of production contexts, including drilling-related operations. This research investigates the effect of optimal process parameters and SPM configuration on the machine tool selection problem versus product demand changes. A review of previous studies suggests that the application of optimization in the feasibility analysis stage of machine tool selection has received less attention by researchers. In this study, a simulated model using genetic algorithm is proposed to find the optimal process parameters and machine tool configuration. During the decision-making phase of machine tool selection, unit …

Cradg: A Chaotic Radg Security System, Salah Albermany, Maryam Nathim, Zahir Hussain

Research outputs 2014 to 2021

A high-performance ciphering algorithm is presented. The proposed method combines old school ciphering (Reaction Automata Direct Graph (RADG)) with chaotic systems to obtain higher level of security. Chaotic sequences are highly sensitive to any changes in their parameters, adding a higher level of security to the proposed approach, called CRADG.

An Experimental Study Of Non-Metallic Inclusions Precipitation And Its Effect On Impact Toughness Variations In Low Alloy Steel Subjected To Complex Deoxidation, Pavel Bizyukov

Dissertations and Theses @ UNI

A low level of non-metallic inclusions in steel is the key requirement in the concept of clean steel. Although the concept has received its name quite recently, it has been implemented at the large-scale steel mills for more than 40 years. Production of clean steel became possible due active development and adoption of the post-melting treatment of molten metal in the teeming ladle. Ladle metallurgy, an umbrella term for various methods of treatment, includes operations that cannot be performed during primary metallurgical processes such as melting in an electric arc, basic oxygen, or air induction furnace. Initially, the most common …

Smartphone Based Ubiquitous Sensing Platform Leveraging Audio Jack For Power And Communication, Ranjana Joshi

Dissertations and Theses @ UNI

With the popularization of smartphones, various smartphone centric ubiquitous sensing applications, which use a smartphone in conjunction with external sensors for data acquisition, processing, display, communication, and storage, have emerged. Because smartphones do not have a universal data interfaces, many ubiquitous sensing applications use the earphone and the microphone channels of the 3.5mm audio interface for data communications so that they can work with various types of smartphones. The earphone channels of the 3.5mm audio interface can only send AC signal out of a smartphone, hence DC power needs to be harvested from the earphone channels.

In this research, based …

Investigation Of The Thermal Performance Of Sierpinski Carpet Fractal Fins In A Natural Convection Environment, Jennifer P. Shaffer

Honors College Theses

This experimental investigation studies the thermal performance of the first four iterations of the Sierpinski carpet pattern in a natural convection environment. This particular fractal geometry is promising in that it increases the available surface area for heat transfer while simultaneously decreasing the mass of the system. This makes it a potentially advantageous design for fins or heat sinks, especially in aerospace applications where minimizing mass of the system is essential. The thermal performance was evaluated by comparing the efficiency, effectiveness, and effectiveness per unit mass for each fractal iteration. The results indicate that efficiency decreases with each fractal iteration …

Improving Sensitivity Of Electrochemical Sensors With Convective Transport In Free-Standing, Carbon Nanotube Structures, Benjamin J. Brownlee, Kevin M. Marr, Jonathan C. Claussen, Brian D. Iverson

Faculty Publications

High-aspect-ratio, porous membrane of vertically-aligned carbon nanotubes (CNTs) were developed through a templated microfabrication approach for electrochemical sensing. Nanostructured platinum (Pt) catalyst was deposited onto the CNTs with a facile, electroless deposition method, resulting in a Pt-nanowire-coated, CNT sensor (PN-CNT). Convection mass transfer enhancement was shown to improve PN-CNT sensor performance in the non-enzymatic, amperometric sensing of hydrogen peroxide (H₂O₂). In particular, convective enhancement was achieved through the use of high surface area to fluid volume structures and concentration boundary layer confinement in a channel. Stir speed and sensor orientation especially influenced the measured current in …

Gradient-Based Optimization Of Wind Farms With Different Turbine Heights, Andrew P.J. Stanley, Jared Thomas, Andrew Ning, Jennifer Annoni, Katherine Dykes, Paul Fleming

Faculty Publications

Turbine wakes reduce power production in a wind farm. Current wind farms are gen- erally built with turbines that are all the same height, but if wind farms included turbines with different tower heights, the cost of energy (COE) may be reduced. We used gradient-based optimization to demonstrate a method to optimize wind farms with varied hub heights. Our study includes a modified version of the FLORIS wake model that accommodates three-dimensional wakes integrated with a tower structural model. Our purpose was to design a process to minimize the COE of a wind farm through layout optimization and varying turbine …

Optimal Combined Long-Term Facility Design And Short-Term Operational Strategy For Chp Capacity Investments, Jose Mojica, Damon Petersen, Brigham Hansen, Kody Powell, John Hedengren

Faculty Publications

This work presents a detailed case study for the optimization of the expansion of a district energy system evaluating the investment decision timing, type of capacity expansion, and fine-scale operational modes. The study develops an optimization framework to find the investment schedule over 30 years with options of investing in traditional heating sources (boilers) or a next-generation combined heat and power (CHP) plant that provides heat and electricity. In district energy systems, the selected capacity and type of system is dependent on demand-side requirements, energy prices, and environmental costs. This work formulates capacity planning over a time horizon as a …

Extending The Upper Temperature Range Of Microchip Gas Chromatography Using A Heater/Clamp Assembly, Abhijit Ghosh, Jacob E. Johnson, Johnathan G. Nuss, Brittany A. Stark, Aaron R. Hawkins, Luke T. Tolley, Brian D. Iverson, H. Dennis Tolley, Milton L. Lee

Faculty Publications

Miniaturization of gas chromatography (GC) instrumentation is of interest because it addresses current and future issues relating to compactness, portability and field application. While incremental advancements continue to be reported in microchip GC, the current performance is far from acceptable. This lower performance compared to conventional GC is due to factors such as pooling of the stationary phase in corners of non-cylindrical channels, adsorption of sensitive compounds on incompletely deactivated surfaces, shorter column lengths and less than optimum interfacing to injector and detector. In this work, a microchip GC system was developed that solves the latter challenge, i.e. microchip interfacing …

Imaging Of Super-Fast Dynamics And Flow Instabilities Of Superconducting Vortices, L. Embon, Y. Anahory, Ž L. Jelić, E. O. Lachman, Y. Myasoedov, M. E. Huber, G. P. Mikitik, A. V. Silhanek, M. V. Milošević, A Gurevich, E. Z. Zeldov

Physics Faculty Publications

Quantized magnetic vortices driven by electric current determine key electromagnetic properties of superconductors. While the dynamic behavior of slow vortices has been thoroughly investigated, the physics of ultrafast vortices under strong currents remains largely unexplored. Here, we use a nanoscale scanning superconducting quantum interference device to image vortices penetrating into a superconducting Pb film at rates of tens of GHz and moving with velocities of up to tens of km/s, which are not only much larger than the speed of sound but also exceed the pair-breaking speed limit of superconducting condensate. These experiments reveal formation of mesoscopic vortex channels which …

Dynamic Transition Of Vortices Into Phase Slips And Generation Of Vortex-Antivortex Pairs In Thin Film Josephson Junctions Under Dc And Ac Currents, Ahmad Sheikhzada, Alex Gurevich

Physics Faculty Publications

We present theoretical and numerical investigations of vortices driven by strong dc and ac currents in long Josephson junctions described by a nonlinear integro-differential equation which takes into account nonlocal electrodynamics of films, vortex bremsstrahlung, and Cherenkov radiation amplified by the attraction of vortices to the edges of the junction. This work focuses on the dynamics of vortices in Josephson junctions in thin films where the effects of Josephson nonlocality are essential but London screening is negligible. We obtained an exact solution for a vortex driven by an arbitrary time-dependent current in an overdamped junction where the vortex turns into …

Cryogenic Rf Test Of The First Srf Cavity Etched In An Rf Ar/Cl2 Plasma, J. Upadhyay, A. Palczewski, S. Popovic, A.-M. Valente-Feliciano, Do Im, H. L. Phillips, L. Vuskovic

Physics Faculty Publications

An apparatus and a method for etching of the inner surfaces of superconducting radio frequency (SRF) accelerator cavities are described. The apparatus is based on the reactive ion etching performed in an Ar/Cl₂ cylindrical capacitive discharge with reversed asymmetry. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity was used. The single cell cavity was mechanically polished and buffer chemically etched and then rf tested at cryogenic temperatures to provide a baseline characterization. The cavity's inner wall was then exposed to the capacitive discharge in a mixture of …

Controlled Manipulation Of Floating Objects On Deformed Fluid Interfaces And Conditions For Stable Equilibria, Jose M. Carballo, Qi Ni, Jose Vasquez, Nathan B. Crane

Faculty Publications

At the millimeter scale, interactions between floating and semi-immersed objects are significant. The local curvature of the interface is modified by the weight/buoyancy forces of floating objects, and by the surface properties of semi-immersed objects. The curvature changes generate attractive (or repulsive) interactions between floating parts, and semi-immersed objects. This work demonstrates how electrowetting can manipulate these interactions in order to position, align, assemble and transport parts attached to the fluid interface. This demonstrates one way in which fluid interfaces can provide an alternative to standard pick and place technology for part positioning/assembly. Typically, the part/rod forces are purely attractive …