Computer Engineering Commons^™

Performance Analysis For Direction Of Arrival Estimating Algorithms, Pradhumna Shrestha, Michael Hempel, Puttipong Mahasukhon, Tao Ma, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Smart antennas have emerged as one of the most promising directions in supporting maximum communication link throughput. In this paper, we have investigated the impact of smart antennas on a complex mobile network such as a railroad wireless communications system. The objective is to analyze the selection of a Direction-Of-Arrival (DOA) estimation algorithm which provides the maximum efficiency when deployed in our railroad testbeds for wireless vehicular communication. Our findings are discussed to provide an indepth understanding of how different algorithms should be selected to support efficient network operations.

Quantitative Performance Analysis Of 3.65 Ghz Mobile Wimax, Pradhumna Shrestha, Michael Hempel, Puttipong Mahasukhon, Tao Ma, Hamid Sharif

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

3.65 GHz Mobile WiMAX spectrum is often a better commercial solution due to its attractive licensing requirements, in spite of the slightly lower coverage area. However, no significant performance data has been reported for 3.65 GHz equipment behavior. In this paper, we have presented an in depth analysis of a 3.65 GHz Mobile WiMAX solution. Our reported data can also contribute in performing link budget analyses and benchmarking similar equipment.

Impact Of Wireless Communication Delay On Load Sharing Among Distributed Generation Systems Through Smart Microgrids, Song Ci, Junjie Qian, Dalei Wu, Ali Keyhani

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Load sharing among distributed generation systems (DGS) is one of the most important topics in wireless-enabled smart microgrids, where a set of power inverters at different geographical locations work coordinately and collaboratively through wireless networks to meet the load requirement. Parallel power inverters operated in distributed generation systems rely on the underlying wireless communication channels to exchange power information among them for load sharing control. However, existing work in the area of load sharing has largely ignored the effect of wireless communication delay. Study has shown that the time-varying wireless communication delay may have a significant impact on the performance …

Forensic Analysis Of Social Networking Applications On Mobile Devices, Noora Al Mutawa, Ibrahim Baggili, Andrew Marrington

Electrical & Computer Engineering and Computer Science Faculty Publications

The increased use of social networking applications on smartphones makes these devices a goldmine for forensic investigators. Potential evidence can be held on these devices and recovered with the right tools and examination methods. This paper focuses on conducting forensic analyses on three widely used social networking applications on smartphones: Facebook, Twitter, and MySpace. The tests were conducted on three popular smartphones: BlackBerrys, iPhones, and Android phones. The tests consisted of installing the social networking applications on each device, conducting common user activities through each application, acquiring a forensically sound logical image of each device, and performing manual forensic analysis …

Novelty-Assisted Interactive Evolution Of Control Behaviors, Brian G. Woolley

Electronic Theses and Dissertations

The field of evolutionary computation is inspired by the achievements of natural evolution, in which there is no final objective. Yet the pursuit of objectives is ubiquitous in simulated evolution because evolutionary algorithms that can consistently achieve established benchmarks are lauded as successful, thus reinforcing this paradigm. A significant problem is that such objective approaches assume that intermediate stepping stones will increasingly resemble the final objective when in fact they often do not. The consequence is that while solutions may exist, searching for such objectives may not discover them. This problem with objectives is demonstrated through an experiment in this …

A Simulation Analysis Of Photovoltaic Ac Module Integrated Converters In Parallel, Under Controlled Edge Shading Conditions, Lynette O'Callaghan, Mick Mckeever, Brian Norton

Conference Papers

A DC and AC power simulation comparison of: a Photovoltaic (PV) array with a modular, parallel, AC converter configuration; and a series, string configuration with a central AC converter, is presented. The systems are simulated using a comprehensive range of edge shading scenarios and irradiance conditions. Power control and transformation circuitry must be designed for shade and module mismatch tolerance to prevent over-proportional power to shade losses, as average losses from Building Integrated PV (BIPV) systems are approximately 20 to 25%, due to shade, mismatch, differences in orientation and inclination, and temperature effects. 59.4% of the simulations showed gains in …

Comparing Android Applications To Find Copying, Larry Melling, Bob Zeidman

Journal of Digital Forensics, Security and Law

The Android smartphone operating system includes a Java virtual machine that enables rapid development and deployment of a wide variety of applications. The open nature of the platform means that reverse engineering of applications is relatively easy, and many developers are concerned as applications similar to their own show up in the Android marketplace and want to know if these applications are pirated. Fortunately, the same characteristics that make an Android application easy to reverse engineer and copy also provide opportunities for Android developers to compare downloaded applications to their own. This paper describes the process for comparing a developer’s …

Forensic Evidence Identification And Modeling For Attacks Against A Simulated Online Business Information System, Manghui Tu, Dianxiang Xu, Eugene Butler, Amanda Schwartz

Journal of Digital Forensics, Security and Law

Forensic readiness of business information systems can support future forensics investigation or auditing on external/internal attacks, internal sabotage and espionage, and business fraud. To establish forensics readiness, it is essential for an organization to identify which fingerprints are relevant and where they can be located, to determine whether they are logged in a forensically sound way and whether all the needed fingerprints are available to reconstruct the events successfully. Also, a fingerprint identification and locating mechanism should be provided to guide potential forensics investigation in the future. Furthermore, mechanisms should be established to automate the security incident tracking and reconstruction …

To License Or Not To License Updated: An Examination Of State Statutes Regarding Private Investigators And Digital Examiners, Thomas Lonardo, Doug White, Alan Rea

Journal of Digital Forensics, Security and Law

In this update to the 2009 year's study, the authors examine statutes that regulate, license, and enforce investigative functions in each US state. After identification and review of Private Investigator licensing requirements, the authors find that very few state statutes explicitly differentiate between Private Investigators and Digital Examiners, but do see a trend of more states making some distinction. The authors contacted all state regulatory agencies where statutory language was not explicit, and as a result, set forth the various state approaches to professional Digital Examiner licensing. As was the case in the previous two iterations of this research, the …

Dns In Computer Forensics, Neil F. Wright

Journal of Digital Forensics, Security and Law

The Domain Name Service (DNS) is a critical core component of the global Internet and integral to the majority of corporate intranets. It provides resolution services between the human-readable name-based system addresses and the machine operable Internet Protocol (IP) based addresses required for creating network level connections. Whilst structured as a globally dispersed resilient tree data structure, from the Global and Country Code Top Level Domains (gTLD/ccTLD) down to the individual site and system leaf nodes, it is highly resilient although vulnerable to various attacks, exploits and systematic failures.

Simulation Visualization Rhetoric And It's Practical Implications, D'An Knowles Ball, Andrew J. Collins

Engineering Management & Systems Engineering Faculty Publications

Modeling and simulation has moved far beyond simple data representation into the world of visual communication over the past 15 years; ultimately, the acceptance of M&S within mainstream science and society will depend on the results that are produced visually. A simulation’s function is of primary importance to its end result, but it cannot be denied that the discipline of M&S now prizes fancy graphics to communicate. Rhetorical methodological decisions have the greatest impact on the end user, and considerations that bring visual rhetoric to modeling and simulation should be examined as a necessity to application. This paper will expose …

Kinect And 3d Gis In Archaeology, Heather Richards-Rissetto, Fabio Remondino, Jim Robersson, Jennifer Von Schwerin, Giorgio Agugiaro, Gabrio Girardi

Department of Anthropology: Faculty Publications

This paper explores the potential of using Microsoft's Kinect to create a low-cost and portable system to virtually navigate, through a prototype 3D GIS, the digitally reconstructed ancient Maya city and UNESCO World Heritage Site of Copan in Honduras. The 3D GIS, named QueryArch3D, was developed as part of the MayaArch3D project (http://mayaarch3d.unm.edu), which explores the possibilities of integrating databases and 3D digital tools for research and teaching on ancient architectures and landscapes. The developed system, based on the Flexible Action and Articulated Skeleton Toolkit (FAAST), controls in a remote and touchless mode the movements in the 3D environment in …

Dynamic Reconfigurable Multi-Cell Battery: A Novel Approach To Improve Battery Performance, Song Ci, Jiucai Zhang, Hamid Sharif, Mahmoud Alahmad

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Many electronic systems such as robotics, battery powered electric vehicles, and mobile computing devices are powered by multi-cell battery with limited energy capacity. Therefore, maximizing the battery performance such as operating time, available capacity, and lifetime is one of the major battery design challenges. Traditional approaches such as dynamic power management to maximize the battery discharge performance have treated multi-cell battery as a pure passive component with a fixed configuration. Thus, the multi-cell battery performance is determined by the weakest battery cell, leading to a low utilization of battery energy. In this paper, we propose a novel multi-cell battery design …

Ipad2 Logical Acquisition: Automated Or Manual Examination?, Somaya Ali, Sumaya Alhosani, Farah Alzarooni, Ibrahim Baggili

Electrical & Computer Engineering and Computer Science Faculty Publications

Due to their usage increase worldwide, iPads are on the path of becoming key sources of digital evidence in criminal investigations. This research investigated the logical backup acquisition and examination of the iPad2 device using the Apple iTunes backup utility while manually examining the backup data (manual examination) and automatically parsing the backup data (Lantern software-automated examination).The results indicate that a manual examination of the logical backup structure from iTunes reveals more digital evidence, especially if installed application data is required for an investigation. However, the researchers note that if a quick triage is needed of an iOS device, then …

Examination Of The Nonlinear Dynamics Of A Chaotic Acousto-Optic Bragg Modulator With Feedback Under Signal Encryption And Decryption, Mohammed A. Al-Saedi, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

An acousto-optic Bragg cell with first-order feedback, which exhibits chaotic behavior past the threshold for bistability, was recently examined for possible chaotic encryption and recovery of simple messages (such as low-amplitude periodic signals) applied via the bias input of the sound cell driver. We carry out a thorough examination of the nonlinear dynamics of the Bragg cell under intensity feedback for (i) dc variations of the feedback gain (β˜) and the phase shift parameter (α^ 0) and (ii) ac variations of α^ 0; total under signal encryption, investigating both from two different perspectives: (i) examining chaos in view of the …

Commentary And Interpretations Of Tagore’S 'Ode To Africa', Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

This is a commentary/interpretation of Rabindranath Tagore's poem "Ode to Africa."

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 …

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 …

Strongly Complete Logics For Coalgebras, Alexander Kurz, Jiří Rosický

Engineering Faculty Articles and Research

Coalgebras for a functor model different types of transition systems in a uniform way. This paper focuses on a uniform account of finitary logics for set-based coalgebras. In particular, a general construction of a logic from an arbitrary set-functor is given and proven to be strongly complete under additional assumptions. We proceed in three parts.

Part I argues that sifted colimit preserving functors are those functors that preserve universal algebraic structure. Our main theorem here states that a functor preserves sifted colimits if and only if it has a finitary presentation by operations and equations. Moreover, the presentation of the …

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 …

Visqol: The Virtual Speech Quality Objective Listener, Andrew Hines, Jan Skoglund, Anil Kokaram, Naomi Harte

Conference papers

A model of human speech quality perception has been developed to provide an objective measure for predicting subjective quality assessments. The Virtual Speech Quality Objective Listener (ViSQOL) model is a signal based full reference metric that uses a spectro-temporal measure of similarity between a reference and a test speech signal. This paper describes the algorithm and compares the results with PESQ for common problems in VoIP: clock drift, associated time warping and jitter. The results indicate that ViSQOL is less prone to underestimation of speech quality in both scenarios than the ITU standard.

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.