Computer Engineering Commons^™

Time Dynamics Of Self-Pumped Reflection Gratings In A Photorefractive Polymer, Partha P. Banerjee, S. H. Buller, C. M. Liebig, S. A. Basun, Gary Cook, Dean R. Evans, Pierre-Alexandre Blanche, J. Thomas, Cory W. Christenson, N. Peyghambarian

Electrical and Computer Engineering Faculty Publications

The time dynamics of self-pumped reflection gratings in a commonly used photorefractive polymer PDCST:PVK:ECZ-BBP:C60 with no additional electron sources or traps is investigated. While holes are normally the mobile charges and responsible for grating formation, our experimental observations, analyzed using multi-exponential fitting curves, show evidence of electrons in addition to holes as charge carriers, particularly above an applied field of 40 V/μm.

The dependence of effective carrier mobilities on the applied electric field, deduced from experimental results, show stronger field dependence of electron mobility at high electric fields. At an applied field of 70 V/μm, electron and hole mobilities become …

Enhancing Spectrum Utilization In Dynamic Cognitive Radio Systems, Dusadee Treeumnuk

Electrical & Computer Engineering Theses & Dissertations

Cognitive radio (CR) is regarded as a viable solution to enabling flexible use of the frequency spectrum in future generations of wireless systems by allowing unlicensed secondary users (SU) to access licensed spectrum under the specific condition that no harmful interference be caused to the licensed primary users (PU) of the spectrum. In practical scenarios, the knowledge of PU activity is unknown to CRs and radio environments are mostly imperfect due to various issues such as noise uncertainty and multipath fadings. Therefore, important functionalities of CR systems are to efficiently detect availability of radio spectrum as well as to avoid …

Forecasting Natural Gas Consumption In İstanbul Using Neural Networks And Multivariate Time Series Methods, Ömer Fahretti̇n Demi̇rel, Seli̇m Zai̇m, Ahmet Çalişkan, Pinar Özuyar

Turkish Journal of Electrical Engineering and Computer Sciences

The fast changes and developments in the world's economy have substantially increased energy consumption. Consequently, energy planning has become more critical and important. Forecasting is one of the main tools utilized in energy planning. Recently developed computational techniques such as genetic algorithms have led to easily produced and accurate forecasts. In this paper, a natural gas consumption forecasting methodology is developed and implemented with state-of-the-art techniques. We show that our forecasts are quite close to real consumption values. Accurate forecasting of natural gas consumption is extremely critical as the majority of purchasing agreements made are based on predictions. As a …

Distributed Formal Concept Analysis Algorithms Based On An Iterative Mapreduce Framework, Ruairí De Fréin, Biao Xu, Eric Robson, Mícheál Ó Fóghlú

Conference papers

While many existing formal concept analysis algorithms are efficient, they are typically unsuitable for distributed implementation. Taking the MapReduce (MR) framework as our inspiration we introduce a distributed approach for performing formal concept mining. Our method has its novelty in that we use a light-weight MapReduce runtime called Twister which is better suited to iterative algorithms than recent distributed approaches. First, we describe the theoretical foundations underpinning our distributed formal concept analysis approach. Second, we provide a representative exemplar of how a classic centralized algorithm can be implemented in a distributed fashion using our methodology: we modify Ganter’s classic algorithm …

A Video Encoder Design Combining Edge-Adaptive Lifting And Scalable Block-Matching With Motion Compensation, Sedat Telçeken, Ömer Nezi̇h Gerek

Turkish Journal of Electrical Engineering and Computer Sciences

This study aimed to achieve video compression by using a novel lifting-based hybrid encoder that also uses motion compensation. The proposed encoder separates video frames into temporal groups, within which certain frames are selected for producing temporal and spatial predictions over the rest of the frames. The predictions utilize spatiotemporal lifting together with motion compensation. The combination of spatial information with temporal changes is inspired from the idea of edge-adaptive lifting, which alters prediction directions in images. A further incorporation of well-known block-matching methods with different levels was observed to improve the performance. To provide the first compression results, unpredicted …

Tunable Srr-Based Substrate For A Microstrip Patch Antenna, Adnan Sondaş, Mustafa Hi̇kmet Bi̇lgehan Uçar, Yunus Emre Erdemli̇

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a microstrip patch antenna over an artificial substrate composed of split-ring resonator (SRR) elements is introduced. As the SRR-based substrate provides miniaturization for the patch, metallic loadings placed between the rings of the SRR elements offer frequency-tuning capability. Practical switch models are employed in lieu of those loadings to demonstrate dynamic control of the operational frequency. The full-wave analysis and design of the proposed tunable patch were carried out using CST Microwave Studio, and the cross-comparisons were provided via Ansoft HFSS. Preliminary measurements are also presented, demonstrating the prospective performance of the proposed design.

Research On Cutoff Wavelength Of Dominant Mode And Field Patterns In Trapezoidal Microshield Lines, Hai Sun, Yujiang Wu

Turkish Journal of Electrical Engineering and Computer Sciences

The influence of the position of the metallic signal strip on the cutoff characteristic of the dominant mode and the field patterns in 3 types of trapezoidal microshield lines are calculated by the edge-based finite element method. These trapezoidal microshield lines include trapezoidal microshield lines with a single signal line, dual signal lines, and 3 signal lines. The cutoff wavelength of the dominant mode can be adjusted by changing the dimensions of metallic signal strips as well as by adjusting their positions. Field patterns of the dominant mode and the first-higher-order mode for different dimensions and the dielectric constant of …

A New Multipath Channel Transformation Technique, Tuğrul Çavdar

Turkish Journal of Electrical Engineering and Computer Sciences

A new channel transformation technique is introduced in this paper The technique is employed on the receiver side and has 2 filters. The first filter is the inverse complex conjugate of the estimated channel. The profile of this filter's output is triangular. The taps of the second filter are calculated according to the output of the first filter to produce an exponentially decreasing profile. This technique transforms most channel profiles to exponentially decreasing channel profiles. Thus equalizers adopting the proposed technique may have better bit error rates and lower computational complexity on frequency-selective channels. This paper evaluates the efficiency of …

Effects Of Diacritics On Turkish Information Retrieval, Adi̇l Alpkoçak, Meltem Ceylan

Turkish Journal of Electrical Engineering and Computer Sciences

We investigate the effects of improper use of diacritics in the Turkish alphabet on information retrieval. A diacritic is simply a supplementary sign added to a letter to change the sound value of the letter, and the Turkish alphabet has 5 special letters derived from Latin by adding different diacritics. The statistical analysis performed in this study shows that retrieval performance significantly decreases when documents and queries contain letters with different forms, such that documents consist of letters with diacritics while queries consist of standard Latin letters and vice versa. In order to tackle this challenge, we propose 3 approaches: …

Context Gathering And Management For Centralized Context-Aware Handover In Heterogeneous Mobile Networks, Behrouz Shahgholi Ghahfarokhi, Naser Movahhedinia

Turkish Journal of Electrical Engineering and Computer Sciences

Context-aware handover decision has recently been considered as a candidate for next-generation heterogeneous wireless networks. The context-aware handover methods proposed in the literature differ in some aspects, including the location of the handover decision (distributed or centralized). Depending on the location of the decision point, the appropriate part of the context knowledge should be transferred in those methods. This paper proposes a context gathering mechanism for a policy-based context-aware handover method, which implements mobile-initiated and network assisted handover. The proposed network context gathering mechanism is based on a media-independent handover (MIH) framework and the paper justifies the usability of the …

Observer Path Design By Imitation Of Competing Constraints For Bearing Only Tracking, Ridvan Gürcan, Mesut Kartal

Turkish Journal of Electrical Engineering and Computer Sciences

In the bearing only tracking (BOT) problem the observer tries to estimate the position of the target. The observer maneuver is a requirement to guarantee the uniqueness of the estimation. Determining an observer maneuver for BOT is a difficult problem due to its nonlinear nature. This paper proposes a new method that combines the reference BOT scenarios as a priori knowledge with the incoming bearing measurements to obtain an observer maneuver in a generic optimization framework. The use of a priori knowledge makes the observer maneuver design more realistic. The maneuver recommendation process uses the imitation of competing constraints. In …

A Novel Three-Phase Transformer Hysteresis Model In Matlab^{Tm} Simulink, Okan Özgönenel, Kami̇l Ri̇fat İrfan Güney, Ömer Usta, Hasan Di̇ri̇k

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a new transformer model displaying hysteresis using the MATLAB{\texttrademark} Simulink environment. The proposed model displays a complete scheme for the simulation of 3-phase transformers. The new model is mainly based on the transmission line model and the Jiles-Atherton model of a power system using lumped parameters. Jiles-Atherton model parameters were determined by curve fitting and numerical optimization iteration. The developed model is particularly suitable for fault analysis and protective relaying studies under harmonic conditions where the transformer is driven into the nonlinear regime. The performance of the method was evaluated by both theorical and experimental data.

Graphene-Based Post-Cmos Architecture, Sansiri Tanachutiwat

Legacy Theses & Dissertations (2009 - 2024)

The semiconductor industry relies on CMOS technology which is nearing its scaling limitations. In order to continue the historical growth rate of the device density of digital logic chips, novel nanomaterials and nanodevices will need to be developed.

Openness, Intellectual Property And Standardization In The European Ict Sector, Carl Mair

IP Theory

No abstract provided.

The Application Of Fuzzy Granular Computing For The Analysis Of Human Dynamic Behavior In 3d Space, Murad Mohammad Alaqtash

Open Access Theses & Dissertations

Human dynamic behavior in space is very complex in that it involves many physical, perceptual and motor aspects. It is tied together at a sensory level by linkages between vestibular, visual and somatosensory information that develop through experience of inertial and gravitational reaction forces. Coordinated movement emerges from the interplay among descending output from the central nervous system, sensory input from the body and environment, muscle dynamics, and the emergent dynamics of the whole neuromusculoskeletal system.

There have been many attempts to directly capture the activities of the neuronal system in human locomotion without the ability to clarify how the …

Column: The Physics Of Digital Information-Part 2, Fred Cohen

Journal of Digital Forensics, Security and Law

In part 1 of this series (Cohen, 2011a), we discussed some of the basics of building a physics of digital information. Assuming, as we have, that science is about causality and that a scientific theory should require that cause(C) produces effect (E) via mechanism M (written C→ME), we explore that general theory of digital systems from the perspective of attributing effects (i.e., traces of activities in digital systems) to their causes. Full details of the current version of this physics are available online2 , and in this article, we explore a few more of them.

Technology Corner: Dating Of Electronic Hardware For Prior Art Investigations, Sellam Ismail

Journal of Digital Forensics, Security and Law

In many legal matters, specifically patent litigation, determining and authenticating the date of computer hardware or other electronic products or components is often key to establishing the item as legitimate evidence of prior art. Such evidence can be used to buttress claims of technologies available or of events transpiring by or at a particular date.

Applying The Acpo Principles In Public Cloud Forensic Investigations, Harjinder S. Lallie, Lee Pimlott

Journal of Digital Forensics, Security and Law

The numerous advantages offered by cloud computing has fuelled its growth and has made it one of the most significant of current computing trends. The same advantages have created complex issues for those conducting digital forensic investigations. Digital forensic investigators rely on the ACPO (Association of Chief Police Officers) or similar guidelines when conducting an investigation, however the guidelines make no reference to some of the issues presented by cloud investigations. This study investigates the impact of cloud computing on ACPO’s core principles and asks whether these principles can still be applied in a cloud investigation and the challenges presented …

An Overview Of The Jumplist Configuration File In Windows 7, Harjinder S. Lallie, Parmjit S. Bains

Journal of Digital Forensics, Security and Law

The introduction of Jumplists in Windows 7 was an important feature from a forensic examiners viewpoint. Jumplist configuration files can provide the examiner with a wealth of information relating to file access and in particular: dates/times, Volume GUIDs and unique file object IDs relating to those files. Some of the information in the Jumplist could be used to build a more precise timeline relating to system and file usage. In this article, we analyse the structure of a Jumplist configuration file and in particular a record from a Jumplist configuration file and highlight some of the important entries therein.

Pandora’S Email Box? An Exploratory Study Of Web-Based Email Forgery Detection And Validation., Richard Boddington, Grant Boxall, Jeremy Ardley

Journal of Digital Forensics, Security and Law

Web based email systems may be a source of pristine digital evidence because of the perceived difficulty of client tampering with messages stored inside the email account. We demonstrate that such assumption is wrong in the case of Windows Live Hotmail®1 . Windows Live Mail®1 synchronises message on client-side computers with the Hotmail® server, benefiting users wishing to synchronise their email accounts and personal devices. However, this synchronisation opens an exploit for wrongdoers to tamper with existing email messages and attachments as well as facilitating the insertion of fabricated messages. The exploit process enables persistent storage of tampered and fabricated …

Toward Alignment Between Communities Of Practice And Knowledge-Based Decision Support, Jason Nichols, David Biros, Mark Weiser

Journal of Digital Forensics, Security and Law

The National Repository of Digital Forensics Information (NRDFI) is a knowledge repository for law enforcement digital forensics investigators (LEDFI). Over six years, the NRDFI has undertaken significant design revisions in order to more closely align the architecture of the system with theory addressing motivation to share knowledge and communication within ego-centric groups and communities of practice. These revisions have been met with minimal change in usage patterns by LEDFI community members, calling into question the applicability of relevant theory when the domain for knowledge sharing activities expands beyond the confines of an individual organization to a community of practice. When …

Implementing The Automated Phases Of The Partially-Automated Digital Triage Process Model, Gary Cantrell, David A. Dampier

Journal of Digital Forensics, Security and Law

Digital triage is a pre-digital-forensic phase that sometimes takes place as a way of gathering quick intelligence. Although effort has been undertaken to model the digital forensics process, little has been done to-date to model digital triage. This work discusses the further development of a model that attempts to address digital triage, the Partially-automated Crime Specific Digital Triage Process model. The model itself will be presented along with a description of how its automated functionality was implemented to facilitate model testing.

Table Of Contents

Journal of Digital Forensics, Security and Law

No abstract provided.

Digital Evidence Education In Schools Of Law, Aaron Alva, Barbara Endicott-Popovsky

Journal of Digital Forensics, Security and Law

An examination of State of Connecticut v. Julie Amero provides insight into how a general lack of understanding of digital evidence can cause an innocent defendant to be wrongfully convicted. By contrast, the 101-page opinion in Lorraine v. Markel American Insurance Co. provides legal precedence and a detailed consideration for the admission of digital evidence. An analysis of both cases leads the authors to recommend additions to Law School curricula designed to raise the awareness of the legal community to ensure such travesties of justice, as in the Amero case, don’t occur in the future. Work underway at the University …

Investigation Of The Divcon Neuron To Increase The Performance Of A Traditional Feed Forward Multi-Layer Perceptron And Its Hardware Implementation, Jovan Saenz

Open Access Theses & Dissertations

ABSTRACT

Artificial Neural Networks (ANNs) have been developed in an attempt to emulate the information processing capabilities of the biological brain. They offer an alternate computing approach to problems in which mathematical modeling is complicated, such as pattern recognition and pattern classification.

Since ANNs were proposed in the early 1940s, there has been a great amount of research effort dedicated to the development of new models that improve performance. Consequently, different architectures, a variety of activation functions, and distinct learning algorithms have been developed and implemented in different disciplines such as medicine, engineering, and science. In addition, ANNs have been …

Multi-Physics Modeling Of Induction-Based Additive Manufacturing Of Metals, Danny W. Muse

Open Access Theses & Dissertations

The shift towards 3D printing of functional products has provided a glimpse of the future in terms of manufacturing technologies and the creation of volumetrically complex structures made possible only through these technologies. 3D printing has emerged from the culmination of several technologies covering multiple industries and a myriad of materials. Unlike subtractive technologies such as mills, lathes and CNC machines, where material is removed from a bulk slab or billet to produce a desired part, 3D printing uses an additive layered approach to deposit material based on cross sections of the desired part. Both approaches produce parts based on …

Video Mosaicing Using Inertial Sensors, Arturo Maya Pereyra

Open Access Theses & Dissertations

A method to reduce the process complexity of Video Mosaicing could rely on information concerning the orientation of the camera instead of image feature tracking. Inertial sensors (e.g. accelerometers and gyros) could form part of a low cost motion based technology which can be used in this case and this thesis details an approach for Video Mosaicing based on such technology that requires non-computationally intensive algorithms.

Sensing Through The Continent: Towards Monitoring Migratory Birds Using Cellular Sensor Networks, David Anthony, William P. Bennett, Mehmet C. Vuran, Matthew B. Dwyer, Sebastian Elbaum, Anne Lacy, Mike Engels, Walter Wehtje

School of Computing: Conference and Workshop Papers

This paper presents CraneTracker, a novel sensor platform for monitoring migratory birds. The platform is designed to monitor Whooping Cranes, an endangered species that conducts an annual migration of 4, 000 km between southern Texas and north-central Canada. CraneTracker includes a rich set of sensors, a multi-modal radio, and power control circuitry for sustainable, continental-scale information delivery during migration. The need for large-scale connectivity motivates the use of cellular technology in low-cost sensor platforms augmented by a low-power transceiver for ad-hoc connectivity. This platform leads to a new class of cellular sensor networks (CSNs) for time-critical and mobile sensing applications. …

A Low-Cost, Reliable, High-Throughput System For Rodent Behavioral Phenotyping In A Home Cage Environment, Steven A. Parkison, Jay D. Carlson, Tammy R. Chaudoin, Traci A. Hoke, A. Katrin Schenk, Evan H. Goulding, Lance C. Pérez, Stephen J. Bonasera

Department of Electrical and Computer Engineering: Faculty Publications

Inexpensive, high-throughput, low maintenance systems for precise temporal and spatial measurement of mouse home cage behavior (including movement, feeding, and drinking) are required to evaluate products from large scale pharmaceutical design and genetic lesion programs. These measurements are also required to interpret results from more focused behavioral assays. We describe the design and validation of a highly-scalable, reliable mouse home cage behavioral monitoring system modeled on a previously described, one-ofa- kind system [1]. Mouse position was determined by solving static equilibrium equations describing the force and torques acting on the system strain gauges; feeding events were detected by a photobeam …

Nonlinear Plasmonic Cloaks To Realize Giant All-Optical Scattering Switching, Christos Argyropoulos, Pai-Yen Chen, Francesco Monticone, Giuseppe D'Aguanno, Andrea Alu

Department of Electrical and Computer Engineering: Faculty Publications

Here we extend the reach of Fano resonant coupling by combining this concept with cloaking and plasmonic resonances in a single nonlinear nanoparticle, in order to realize giant all-optical scattering nanoswitches controlled by moderate pumping intensities. We show that a core-shell nonlinear plasmonic particle may be designed to abruptly switch from being completely cloaked to being strongly resonant, with up to a 40 dB cross-sectional difference. Self-tunable optical cloaks and resonant scatterers are envisioned for use as efficient all-optical switches and nanomemories.