Engineering Commons^™

New Architecture For Heterogeneous Real-Time Simulation, Mandar Anil Mathure

Retrospective Theses and Dissertations

This thesis investigates a new architecture for modeling and simulating complex distributed real-time systems. Modeling adequately a large distributed real time system may involve, due to its complexity, several different theoretical vehicles such as queuing theory, finite state machines, and others. Currently there are no software tools, which would offer combining such heterogeneous features into a single comprehensive simulation environment.

This study involves integrating 3 tools, SES/workbench, an offline simulator using queuing theory as its modeling discipline, ObjecTime as a real-time simulator based on finite state machines as its modeling discipline, and VxWorks real-time kernel used for free modeling in …

An Approach To Sequence Dna Without Tagging, Sanjun Niu, Ravi F. Saraf

Ravi Saraf Publications

Microarray technology is playing an increasingly important role in biology and medicine and its application to genomics for gene expression analysis has already reached the market with a variety of commercially available instruments. In these combinatorial analysis methods, known probe single-strand DNA (ssDNA) “primers” are attached in clusters of typically 100 μm × 100 μm pixels. Each pixel of the array has a slightly different sequence. On exposure to “unknown” target ssDNA, the pixels with the right complementary probe ssDNA sequence convert to double-stranded DNA (dsDNA) by a hybridization reaction. To transduct the conversion of the pixel to dsDNA, the …

Fiber Optic Sensor Response To High Levels Of Fat In Cream, Czarena L. Crofcheck, Frederick A. Payne, Clair L. Hicks, M. Pinar Mengüç, Sue E. Nokes

Biosystems and Agricultural Engineering Faculty Publications

A light backscatter technique using optical fibers to deliver and receive light was investigated for measuring the milkfat content of unhomogenized cream. Light backscatter through cream at wavelengths of 450 to 900 nm was measured for fiber separation distances from 2 to 6.5 mm and for cream containing 10 to ~40 weight percent (wt%) milkfat. Unhomogenized cream (~40 wt% milkfat) was mixed with skim milk (~0.05 wt% milkfat) to yield samples with five different milkfat levels. Three optical response models were tested for correlation with milkfat content: one using the light intensity measurement at a single separation distance, the second …

Creep-Fatigue Life Prediction Of Low Alloy Steels, James Toland, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

The creep-fatigue behavior of Cr-Mo steels has been examined from published data. The published data were compiled in an earlier effort and used in this paper to develop a multivariate best-fit equation to predict the low cycle fatigue life. The fatigue test temperatures were representative of temperatures experienced in nuclear power plants, which varied from room temperature to 600°C. Within this temperature range, depending upon the test parameters used, creep and fatigue processes interact and failure occurs in the lowcycle fatigue regime.

Strongly Screened Vortex Lattice Model With Disorder, C. Giardina', Nikolai V. Priezjev, J. M. Kosterlitz

Mechanical and Materials Engineering Faculty Publications

The three dimensional XY model with quenched random disorder and finite screening is studied. We argue that the system scales to model with λ≃0≃T and the resulting effective model is studied numerically by defect energy scaling. In zero external field we find that there exists a true superconducting phase with a stiffness exponent θ≃+1.0 for weak disorder. For low magnetic field and weak disorder, there is also a superconducting phase with θ≃+1.0 which we conjecture is a Bragg glass. For larger disorder or applied field, there is a non superconducting phase with θ≃−1.0. We estimate the critical external field whose …

Stability And Optimization Of Photoconductivity In Thermally Vacuum Evaporated Indium (Iii) Sulfide Thin Films, Gustavo Rehder, Robert Engelken, Randy Stidham, Richard Tanner, Lee Ketchum, Anil Baral

Journal of the Arkansas Academy of Science

Long term stability of photosensitivity versus time in indium (III) sulfide thin films thermally vacuum evaporated onto photocell-patterned printed circuit boards varies sensitively with several factors including contact metal type, contact metal diffusion and electromigration into the semiconductor, doping, and encapsulation method. Because of the significant photoconductivity and relative low toxicity and environmental impact of this compound semiconductor, it is important to better characterize these dependences toward commercial applications. We will report on measurements of photoconductivity vs. time as functions of such factors and evolving methods to stabilize this photoconductivity.

An Analysis Of A Private-Key Cryptosystem, Wei-Wey Tan

Student Works (2000-2009)

In this dissertation, we have presented a new block cipher. The proposed block cipher is a Substitution-Permutation network cryptosystem with a block length of 128 bits and key length of 256 bits. With the increased key length and block size, the proposed block cipher has greater security over DES. A modular design approach was applied. The cipher has three major building blocks and their interaction has been carefully chosen to achieve better security and performance. Algorithmic S­-Boxes are used to provide confusion and nonlinearity in the cipher. The proposed cipher uses a highly diffusive diffusion layer, which is a combination …

A Genetic Algorithm Solution To The Shortest Path Problem In Ospf And Mpls, Wee Jing Tee Wee Jing

Student Works (2000-2009)

This project studies and explores the potential of using genetic algorithm to solve the shortest path problem in Open Shortest Path First (OSPF) and Multiprotocol Label Switching (MPLS). The most critical task for developing a genetic algorithm to the shortest path problem is to how to encode a path in a network. In this project, two genetic algorithm solutions arc developed for the above two problem domains, i.e. Previous-node-based Encoding to solve the shortest path problem in OSPF and Priority-based Encoding to solve the shortest path problem in MPLS. For each of the shortest path problem domains, the proposed solution …

Level Set Segmentation Of Mr Images For Extraction Of Femur Bone And Tissues, Christina Shanti Nayagam

Student Works (2000-2009)

This research explores a potentially useful segmentation algorithm, known as the level set method. It is suitable for images obtained from the Magnetic Resonance Imaging (MRJ) modality, despite the fact that MR images have low contrast between bone and tissue. The level set method is a numerical technique designed to track the evolution of an interface. The fast marching version of the method is implemented for two-dimensional (2-D) and three-dimensional (3-D) segmentation in this research. Femur segmentation is the main thrust of this thesis, however brain and heart images are also presented. Pre-processing steps are first performed for the 2-0 …

Issues In Implementing Ipv6 In The X-Kernel Simulator, Raja Singam Thillainathan

Student Works (2000-2009)

The new Internet Protocol Version 6(IPv6) or Internet Protocol Next Generation (TPNG) is bound to replace the existing Internet Protocol Version 4(TPv4). This new protocol is to address and resolve the limitations of the existing Internet Protocols. At the moment the new protocol is still in its infancy stage, and it is being implemented by both the research society and the private sector. The x-kernel being a research project done by University of Arizona is freely available on the Internet. This x-kemel is a networking software almost similar to the Berkeley version (BSD) and it is bundled together with a …

Internet Information Server Scanner : Scanning On Url Vulnerabilities, Yu Jin Tan

Student Works (2000-2009)

This dissertation analyzes weaknesses on web servers, focusing on Microsoft's Internet Information Server (HS). As part of the research, an HS scanner (HS-SCAN) has been implemented to probe only on URL vulnerabilities. The need for a vulnerability scanner stems from the alarming number of successful attacks on computer systems that are connected to the Internet. The security flaws threatening e-businesses and the Internet community has prompted bona fide defense measures. Internet firewalls - gateways controlling access between one network and all the others - became a must-have for any organization connecting to the Net. If the firewall is considered the …

The Effect Of Weak Acids Hydrolysis On The Sol-Gel Fabrication Of Silica Thin Film, Abdul Hamid

Student Works (2000-2009)

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Malaysian Automotive Industry's Technological Capabilities In Meeting The Defence Requirements, Ahmad Marzuki Ahmad Nawawi

Student Works (2000-2009)

The end of cold war in late 1980s had totally changed the strategic outlook in the management of military crisis. The revolution in military affairs IRMA) that took place thereafter, had witnessed the importance of technology in determining the national resilience and military power. In modern warfare, technology is considered the main determinant in victory or defeat in the battlefield. The Malaysian Army, realising the need to prepare a lean and mean force to fight a conventional warfare, requires state-of-the-art equipment in order to provide the mobility, firepower and intelligence, which are vital in waging war. All these elements can …

A Vhdl Implementation Of Bist Technique In Uart Design, Mohd. Yamani Idna Idris

Student Works (2000-2009)

No abstract provided.

Modelling Of Space Charge Effects In The Electrical Discharge Of Nitrogen Gas Laser, Chin Yang Chia

Student Works (2000-2009)

A computer model for the simulation of a nitrogen gas discharge has been built and studied. This model was based on the fluid description of the discharge plasma. The Phoenical SHASTA Flux-Corrected Transport (FCT) algorithm is used for the solution of the fluid equations and its accuracy has been tested. The distribution of the local electrical field was calculated by the Poisson equation. The internal discharge current was calculated by Sato's equation. The motion of the charge particles was taken into account. The electrical discharge behavior was simulated by the circuit equation and solved using the fourth order Runge-Kutta method …

Active Noise Control Using Adaptive And Advanced Control Techniques, Michael O'Brien

Theses

The theory and application of Active Noise Control to remove irritating acoustic pollution from a variety of sources has and continues to receive significant attention from both theoreticians and practitioners.

While a classical acoustic noise problem is the rejection of acoustic tonal disturbances with the most common solution employed being the celebrated filtered-X LMS algorithm, this thesis shows that the presence of non-linearly induced harmonics at multiple frequencies of the original tone often results in poor performance of this algorithm. It is further found that the noise reduction at these problematic harmonics can be improved in a number of ways, …

Design And Analysis Of Radio Frequency Deployment Algorithms For Gsm, Mónica Pérez-Carbonell

Theses

Due to the growth of the subscriber base and the introduction of new services, mobile communications networks’ demand for wireless resources is increasing. This has resulted in an increasing need to change the frequency allocation of a network in order to adapt the cellular network to new frequency demands.

Currently, a planning tool generates a new frequency plan, which is. then deployed to cell sites. The deployment should ideally be carried out with minimum disruption to network operation, which makes this deployment process a critical undertaking as any errors during or after the deployment can leave the network with poor …

Design Of Low Phase Drift Cmos Frequency Synthesisers, Cyril Patrick Hervé Florent Lahuec

Theses

This thesis presents a methodology for the development of high performance video clock synthesisers that have high (2000) input to output clock multiplication ratios. The synthesisers are required to be compatible with standard CMOS technologies and they must exhibit very low drift between their input and output clocks.

The methodology used borrows techniques established for RF synthesisers in the GHz range. In the RF domain there are significant constraints on spectral spread and because of this there has been significant interest in phase noise generated by intrinsic device noise. Simple and accurate models were developed that help understand the up …

Servo Response And Modelling Issues In Generalised Predictive Control, Ben Griffin

Theses

One of the more popular control strategies, of late, is the Generalised Predictive Controller (GPC). It has received widespread dissemination in academia and numerous successful applications in industry testify to its usefulness. Its popularity partly stems from its superiority to its predecessors, e.g. the generalised minimum variance and pole-placement controllers, but also from the GPC ‘tuning knobs’, which have simple time-domain interpretations and extremely robust default settings. However, despite the widespread interest, there would appear to be some issues relating to the specification of the closed-loop serv^o response that have not been covered in any great detail in the GPC …

Adaptive Radio Resource Management For 2.5g Cellular Networks, Ken Murray

Theses

Recent years have seen a dramatic increase in demand for mobile communication services and with the introduction of 2.5G services such as general packet radio service, this trend is expected to increase further. These new services will introduce highly dynamic tele-traffic variations due to the inherent variability in resource usage of the new data services. The net effect will be considerable increase in load on the available radio resources. The currently employed fixed channel allocation scheme lacks the flexibility to support such traffic variations. A plethora of dynamic channel allocation schemes have been proposed in the past in an effort …

Extensible Data Storage And Presentation Technology For An Ophthalmology Electronic Patient Record, Markus H. Heinrichs

Theses

The Electronic Patient Record (EPR) is a central element of practice systems used in ophthalmology. It acts as a repository for multi-media patient care data as well as billing information, serving healthcare providers and ultimately their patients. The aim of this thesis is to create both a data structure and a flexible on-screen representation of an EPR for an ophthalmology practice, and to provide an XML-based experimental prototype as a “proof of concept” which could ultimately be used as an replacement for an existing DOS- based solution. The medical background and requirements for this system will be described. The state-of-the-art …

Prediction Of Electric Load Using Kohonen Maps - Application To The Polish Electricity Consumption, Amaury Lendasse, M. Cottrell, V. Wertz, M. Verleysen

Engineering Management and Systems Engineering Faculty Research & Creative Works

The Problem of Electrical Load Forecasting Presents Some Particularities, Compared to the Generic Problem of Time-Series Prediction. One of These Particularities is that Several Values (Corresponding to One Day of Consumption) Are Usually Expected as the Result of the Prediction. in This Paper, We Propose an Original Method Dividing the Problem into Three Parts: Prediction of the Daily Mean, of the Daily Standard Deviation and of the Normalized Daily Profile. for the Mean and the Standard Deviation, Radial Function Networks Are Used as Nonlinear Approximations. for the Normalized Profile, a Method based on Kohonen Maps is Proposed. This Method is …

Esd Currents And Fields On The Vcp And The Hcp Modeled Using Quasi-Static Approximations, David Pommerenke, Wang Kai, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

The horizontal coupling plane (HCP) and the vertical coupling plane (VCP) are essential elements of the standardized electrostatic discharge (ESD) test. They are used for testing the robustness of equipment against indirect (nearby) discharges. This article analyzed the current and the fields on the HCP and the VCP using plane wave, transmission line, quasi-static theory. The objective is to illustrate the dominating physical processes on these planes. The work is based on measurements of the transient currents and fields using broadband sensors.

Normalized Natural Gradient Adaptive Filtering For Sparse And Nonsparse Systems, Steven L. Grant, S.C. Douglas

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces a class of normalized natural gradient algorithms (NNG) for adaptive filtering tasks. Natural gradient techniques are useful for generating relatively simple adaptive filtering algorithms where the space of the adaptive coefficients is curved or warped with respect to Euclidean space. The advantage of normalizing gradient adaptive filters is that constant rates of convergence for signals with wide dynamic ranges may be achieved. We show that the so-called proportionate normalized least mean squares (PNLMS) algorithm, an adaptive filter that converges quickly for sparse solutions, is in fact an NNG on a certain parameter space warping. We also show …

On The Interior Resonance Problem When Applying A Hybrid Fem/Mom Approach To Model Printed Circuit Boards, Yun Ji, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

A hybrid finite element method/method of moments (FEM/MoM) technique is used to analyze a printed circuit board power bus structure where the source and observation points are in the near field. The FEM is used to model the lossy region between the planes of the board including the source. The MoM is used to model the region outside the planes and provide a radiation boundary condition to terminate the FEM mesh. Numerical results for a bridged power bus structure are compared with measurements. A nonphysical interior resonance of the electric field integral equation is observed. The problem can be avoided …

On The Modeling Of A Gapped Power-Bus Structure Using A Hybrid Fem/Mom Approach, Yun Ji, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

A hybrid finite-element-method/method-of-moments (FEM/MoM) approach is applied to the analysis of a gapped power-bus structure on a printed circuit board. FEM is used to model the details of the structure. MoM is used to provide a radiation boundary condition to terminate the FEM mesh. Numerical results exhibit significant errors when the FEM/MoM boundary is chosen to coincide with the physical boundary of the board. These errors are due to the inability of hybrid elements on the boundary to enforce the correct boundary condition at a gap edge in a strong sense. A much better alternative is to extend the MoM …

Power Bus Isolation Using Power Islands In Printed Circuit Boards, J. Chen, Todd H. Hubing, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Power islands are often employed in printed circuit board (PCB) designs to alleviate the problem of power bus noise coupling between circuits. Good isolation can be obtained over a wide frequency band due to the large series impedance provided by the gap between the power islands. However, power bus resonances may degrade the isolation at high frequencies. The amount of isolation also depends on the type of connection between power islands and the components on the board. This paper experimentally investigates the effectiveness of several power island structures up to 3.0 GHz

Reduced-Parts-Count Multilevel Rectifiers, Keith Corzine, J. R. Baker

Electrical and Computer Engineering Faculty Research & Creative Works

Multilevel power converters have gained much attention in recent years due to their high power quality, low switching losses, and high-voltage capability. These advantages make the multilevel converter a candidate topology for the next generation of naval ship prolusion systems. The primary disadvantage of these systems is the large number of semiconductors involved. This paper presents a reduced-parts-count rectifier which is well suited for naval rectifier applications where bidirectional power flow is not required. The proposed converter is analyzed and experimentally verified on an 18-kW four-level rectifier/inverter system.

Analysis Of A Four-Level Dc/Dc Buck Converter, Keith Corzine, J. Yuen, J. R. Baker

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a four-level DC/DC buck power converter is introduced. The primary application for this converter is to regulate the center capacitor voltage in a four-level inverter system. The steady-state and average-value models for the proposed converter are developed and compared in simulation. The converter was constructed in the laboratory and verified on a four-level motor drive system. It was shown that the four-level DC/DC converter provides capacitor voltage balancing and allows higher output voltage utilization from the inverter.

Neodymium And Erbium Coordination Environments In Phosphate Glasses, Mevlüt Karabulut, G. K. Marasinghe, Ezzeldin Metwalli, Andrew K. Wittenauer, Richard K. Brow, C. H. Booth, D. K. Shuh

Materials Science and Engineering Faculty Research & Creative Works

The local structures of Nd3+ and Er3+ ions in two series of rare-earth (RE) phosphate glasses with nominal compositions xR203-(1-x)P2O5, where R=Nd and Er and 0.05≤x≤0.28, have been characterized by LIII-edge extended x-ray-absorption fine-structure spectroscopy (EXAFS). The RE coordination number depends on the R2O3 content, decreasing from 9.0 (10) oxygen nearest neighbors in ultraphosphate compositions (x<0.15) to 6.4 (9) oxygen nearest neighbors for the metaphosphate (x∼0.25) compositions. The average Er-O bond distance decreases from 2.29 (1) to 2.23 (1) Å, and the average Nd-O bond distance decreases from 2.40 (1) to 2.37 (1) Å over the same compositional range. The changes in coordination environments are consistent with the conversion of isolated RE polyhedra to clustered RE polyhedra sharing common oxygens as the number of available terminal oxygens per RE ion decreases with increasing x.