Digital Commons Network^™

A Proactive Forward Error Control Scheme For Mobile Wimax Communication, Iftekhar Ahmad, Daryoush Habibi

Research outputs pre 2011

The IEEE 802.16 standard, also known as WiMAX, has yet to prove its effectiveness when the end terminals are not static and free to move at vehicular speeds. High bit error rate caused by multipath fading at high vehicular speeds, is the key reason for low throughput at high speeds. Standard error control mechanisms like transmission control protocol (TCP) and forward error correction (FEC) have limited impact on the overall throughput at vehicular speeds. In this paper, we propose a proactive FEC scheme that adjusts the FEC code size based on the estimated bit error rate at various vehicular speeds. …

Source Localisation In Wireless Sensor Networks Based On Optimised Maximum Likelihood, Mohammed Rahman, Daryoush Habibi, Iftekhar Ahmad

Research outputs pre 2011

Maximum likelihood (ML) is a popular and effective estimator for a wide range of diverse applications and currently affords the most accurate estimation for source localisation in wireless sensor networks (WSN). ML however has two major shortcomings namely, that it is a biased estimator and is also highly sensitive to parameter perturbations. An Optimisation to ML (OML) algorithm was introduced that minimises the sum-of-squares bias and exhibits superior performance to ML in statistical estimation, particularly with finite datasets. This paper proposes a new model for acoustic source localisation in WSN, based upon the OML estimation process. In addition to the …

Fast Evaluation Of The Square Root And Other Nonlinear Functions In Fpga, Stefan Lachowicz, Hans-Joerg Pfleiderer

Research outputs pre 2011

The paper presents a novel method of evaluating the square root function in FPGA. The method uses a linear approximation subsystem with a reduced size of a look-up table. The reduction in the size of the lookup table is twofold. Firstly, a simple linear approximation subsystem uses the lookup table only for the node points. Secondly, a concept of a variable step look-up table is introduced, where the node points are not uniformly spaced, but the spacing is determined by how close to the linear function the approximated function is. The proposed method of evaluating nonlinear function and specifically the …

The Use Of Neural Networks In The Prediction Of The Stock Exchange Of Thailand (Set) Index, Suchira Chaigusin, Chaiyaporn Chirathamjaree, Judith Clayden

Research outputs pre 2011

Prediction of stock prices is an issue of interest to financial markets. Many prediction techniques have been reported in stock forecasting. Neural networks are viewed as one of the more suitable techniques. In this study, an experiment on the forecasting of the Stock Exchange of Thailand (SET) was conducted by using feedforward backpropagation neural networks. In the experiment, many combinations of parameters were investigated to identify the right set of parameters for the neural network models in the forecasting of SET. Several global and local factors influencing the Thai stock market were used in developing the models, including the Dow …

Towards Automated Test Sequence Generation, Usman Farooq, Chiou Peng Lam, Huaizhong Li

Research outputs pre 2011

The article presents a novel control-flow based test sequence generation technique using UML 2.0 activity diagram, which is a behavioral type of UML diagram. Like other model-based techniques, this technique can be used in the earlier phases of the development process owing to the availability of the design models of the system. The activity diagram model is seamlessly converted into a colored Petri net. We proposed a technique that enables the automatic generation of test sequences according to a given coverage criteria from the execution of the colored Petri nets model. Two types of structural coverage criteria for AD based …

Supporting Component Selection With A Suite Of Classifiers, Valerie Maxville, Chiou Peng Lam, J Armarego

Research outputs pre 2011

Software selection involves the assimilation of information and results for each candidate to enable a comparison for decisions to be made. The processes and tools developed assist with software selection to enhance quality, documentation and repeatability. The CdCE process aims to retain and document the information used in selection to assist decisions and to document them for reference as the system evolves. This paper describes the CdCE process and our approach to assist the shortlisting of candidates through a suite of classifiers. The application of the suite is illustrated using a selection and evaluation case study. Applying this approach helps …

Mutation Analysis For The Evaluation Of Ad Models, Usman Farooq, Chiou Peng Lam

Research outputs pre 2011

UML has became the industry standard for analysis and design modeling. Model is a key artifact in Model Driven Architect (MDA) and considered as an only concrete artifact available at earlier development stages. Error detection at earlier development stages can save enormous amount of cost and time. The article presents a novel mutation analysis technique for UML 2.0 Activity Diagram (AD). Based on the AD oriented fault types, a number of mutation operators are defined. The technique focuses on the key features of AD and enhances the confidence in design correctness by showing the absence of control-flow and concurrency related …

Morphology Independent Dynamic Locomotion Control For Virtual Characters, Adrian Boeing

Research outputs pre 2011

Physically based animation of virtual characters is an attractive technology for computer games. It enables characters to dynamically react to interactions with the environment. Existing dynamic simulation controllers are often complex to understand and manipulate, and so are of limited use for animators. This paper presents an extended spline-based control strategy similar to splines used in standard keyframe animation techniques. Unlike existing dynamic control strategies, this allows animators to modify the control system parameters in a manner similar to traditional kinematic animation techniques. A genetic algorithm is employed to produce the initial control parameters for the desired gait, and extend …

Optimized Wlan Mac Protocol For Multimedia Applications, Hushairi Zen, Daryoush Habibi, Alexander Rassau, Iftekhar Ahmad

Research outputs pre 2011

In this paper we propose an optimized WLAN MAC protocol for multimedia applications. The proposed MAC protocol consist of 3 main optimizing architectures, traffic segregation, specific service interval (SI) for voice and video traffic and smaller contention window (CW). Traffic segregation segregates real-time traffic from best-effort traffic while specific service interval provides voice and video traffic with the SI based on its mean arrival rate. In the contention time frame, the CW is made smaller to reduce delay and increase throughput. Ns2 is used as a simulating tool to compare the results of our proposed protocol with the legacy 802.11 …

Converging Voice, Video And Data In Wlan With Qos Support, Hushairi Zen, Daryoush Habibi, Justin Wyatt, Iftekhar Ahmad

Research outputs pre 2011

Providing quality of service (QoS) for converging traffic in wireless local area network (WLAN) is still a major issue for the researchers and industries. Due to the limited bandwidth and exposure to unpredictable interferences in a wireless environment, efficient management and optimization of the access protocols are essential to provide acceptable QoS for real-time traffic and fairness to best-effort traffic. In this paper, we investigate the throughput and delay performance of the legacy IEEE 802.11 and the 802.11e when carrying converging data in WLAN. We evaluate our recently proposed protocol known as wireless token network protocol (WTN) and show that …

Node Admission Control For Multimedia Traffic In Ad-Hoc Wlans, Hushairi Zen, Daryoush Habibi, Iftekhar Ahmad, Alexander Rassau

Research outputs pre 2011

In this paper, we design an admission control scheme for ad hoc WLAN based on self-restraint mechanism. The self-restraint admission control mechanism is implemented in each of the wireless nodes instead of the access point (AP). It has two important admission control abilities: first, it can restrain itself from joining the network if the network channel is congested; second, a joining node can drop itself from the network if the channel becomes congested as a result of its admission. We simulate an ad hoc WLAN and show that the self-restraining mechanism works effectively in sustaining traffic in ad hoc WLAN …

Using Design-Based Research For The Evolutionary Development Of An Online Metacognitive Tool, Joseph Luca, Mark Mcmahon

Research outputs pre 2011

No abstract provided.

Creating A Web-Based Knowledge-Building Team: Design Of Tasks, Scaffolds And Social Affordances, Catherine Mcloughlin, Joseph Luca

Research outputs pre 2011

In a blended learning environment, where students undertake professional skills development in the workplace, a flexible environment is designed in order to support problem solving in project management. The design of the environment, informed by socio-cultural theory, was intended to support knowledge building among students, and in particular to support exchange of ideas, peer review and commentary on solutions presented to problems, and a reflective space for exchange of ideas. The online environment incorporates a number of functional affordances that scaffold knowledge exchange, collaborative tasks and peer commentary. The design features of the online site are described and a proposed …

An Intelligent Model To Control Preemption Rate Of Instantaneous Request Calls In Networks With Book-Ahead Reservation, Iftekhar Ahmad, Joarder Kamruzzaman, Daryoush Habibi, Farzana Islam

Research outputs pre 2011

Resource sharing between book-ahead (BA) and instantaneous request (IR) reservation often results in high preemption rate of on-going IR calls. High IR call preemption rate causes interruption to service continuity which is considered as detrimental in a QoS-enabled network. A number of call admission control models have been proposed in literature to reduce the preemption rate of on-going IR calls. Many of these models use a tuning parameter to achieve certain level of preemption rate. This paper presents an artificial neural network (ANN) model to dynamically control the preemption rate of on-going calls in a QoS-enabled network. The model maps …

The Effects Of Standards -Based Curriculum Modeling On Preservice Elementary Teachers' Mathematical Content Knowledge, Beliefs, And Attitudes., David I. Kennedy

Graduate Theses, Dissertations, and Problem Reports (ETD)

In this dissertation study the researcher modeled NCTM-standards-based teaching while using different instructional materials in two sections of a college mathematics content course for preservice elementary teachers. One section (n = 29) used a typical college text while the other (n = 30) used innovative middle-school materials. After one semester, participants in both class sections showed significant gains in their mathematics content knowledge, the level of their standards-based beliefs about mathematics, and their attitudes toward mathematics. Mathematics-content gains were greater in the college-text group. Interviews were also conducted. Results suggest that both college texts and innovative middle-school materials can serve …

Experimentalism, Relativity And Quantum Mechanics At A Land Grant Institution: West Virginia University, 1920-1960., Eric S. Wright

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis details the response of a land-grant university to the development of quantum mechanics and relativity across a forty-year period. Concurrently with this, it traces the pattern of normal research at the university to show how the development of new physical theories impacted a representative physics department. The Physics department at West Virginia University at first paid little attention to relativity then after 1924 rejected its theoretical underpinnings. Wholesale acceptance of the theory did not occur until after the replacement of the pre-World War II generation of physicists. Quantum mechanics did not make significant inroads at West Virginia University …

Safety Externalities Of Suvs On Passenger Cars: An Analysis Of The Peltzman Effect Using Fars Data., Maria-Paulina Diosdado-De-La-Pena

Graduate Theses, Dissertations, and Problem Reports (ETD)

In the last decade, Sport Utility Vehicles (SUVs) have become a considerable percentage of the US vehicular fleet, giving rise to several highway safety issues such as: vehicular incompatibility, rollover propensity and offsetting driver behavior. While greater mass, stiffness and dimensions of SUVs relative to passenger cars, are safety advantages of SUVs, they may encourage SUV drivers to engage in a trade off between this new level of safety and risk taking behavior, named Peltzman Effect. In this research a model developed by Levitt and Poter (2001) for drinking drivers is applied to assessing the Peltzman Effect of SUVs and …

A Three-Dimensional Singular Model Of A Magnetic Perpendicular Recording Head With Applications To Inter-Track Interference, P. M. Jermey

School of Engineering, Computing and Mathematics Theses

Two-dimensional models of the read head are not suitable for simulating the replay of the extremely high density data that is expected to be achieved in hard drives using perpendicular recording. By matching a singular function approximation to the Fourier solution at the air-bearing surface (ABS), a three-dimensional analytic model of a shielded giant magnetoresistive head, with side shields, for perpendicular replay is derived in this thesis. An explicit expression for the potential in the ABS is presented and parameters in that expression are accurately estimated for a range of practical head dimensions. Using only a few terms of this …

Information Systems Teaching And Research In West Australian Universities, Janice Burn, Craig Standing, Chad Lin

Research outputs pre 2011

The authors of this chapter examine the current state of the development of information systems (IS) teaching and research within Western Australia (WA). A brief overview of the WA environment is followed by an exploration of teaching and research in the four main universities. This is examined against the framework for the study and, in particular, the impact of social processes (Ariav et al. 1987; Klein et al. 1991) and local contingencies (Culnan et al. 1993; Checkland and Holwell 1998), which are found to be of relevance to historical developments.

Tunable Photonic Rf Signal Processor Using Opto-Vlsi, Budi Juswardy, Feng Xiao, Kamal Alameh

Research outputs pre 2011

A tunable photonic RF signal processor is proposed and demonstrated. The filter structure comprises a reconfigurable Opto-VLSI processor for tunability, arrayed waveguide gratings for wavelength slicing and multiplexing, a custom-made fiber array for wavelength routing and dropping, and high-dispersion fibres for true-time delay generation. The processor structure enables positive and negative weights to be synthesised thus realising arbitrary responses. The proof-of-concept of the tunable photonic RF signal processor is experimentally demonstrated.

Integrated True-Time Delay Unit For Broadband Inteference Nulling In Phased-Array Antenna, Budi Juswardy, Kamal Alameh

Research outputs pre 2011

This paper discusses an integrated true-time delay generation unit based on microminiaturisation of photonic and electronic components. The design, simulation, and performance of important building blocks for implementing a true-time delay-based phased-array antenna are presented.

Proceedings Of The Second Annual Meeting Of The Georgia Association Of Mathematics Teacher Educators Front Matter

Proceedings of the Annual Meeting of the Georgia Association of Mathematics Teacher Educators

Contents of 2nd Annual GAMTE Proceedings Front Matter:

• Proceedings Committee
• Officers of GAMTE
• Purposes and Goals of GAMTE
• Table of Contents
• Letter from President

Virtual Vs. Concrete Manipulatives In Mathematics Teacher Education: A Call For Research, Annita W. Hunt

Proceedings of the Annual Meeting of the Georgia Association of Mathematics Teacher Educators

Are virtual manipulatives as effective as concrete (hands-on) manipulatives to build conceptual understanding of number concepts and relationships in pre-service middle grades teachers? In the past, the use of concrete manipulatives in mathematics courses for Clayton State University’s preservice middle grades teachers has proven to be a very effective way to build conceptual understanding of a variety of mathematical topics. This paper presents an argument for the need for research into the usefulness of virtual manipulatives for enhancing mathematics teacher education and their potential to supplement (or replace?) concrete manipulatives.

Middle Crustal Ductile Deformation Patterns In Southern Tibet: Insights From Vorticity Studies In Mabja Dome, Jackie Langille

All Master's Theses

Mabja Dome, southern Tibet, exposes mid-crustal rocks proposed to have originated from a southward flowing mid-crustal channel. Kinematic, mean kinematic vorticity (Wm), and metamorphic petrography analyses on these mid-crustal rocks were performed to test this hypothesis. Kinematic indicators show a transition with structural depth from top-north and top-south shear to solely top-south shear. Along the northernmost transects, Wm in schists and orthogneisses range from 0.52–0.84 (63–36% pure shear). Wm for quartzites ranges from 0.9–0.99 (27–1% pure shear). Deformation temperatures increase from ~450 °C in the chloritoid-zone to ~700 °C in the sillimanite-zone and were recorded between ~35–16 Ma. These patterns …

Energy Budget Analysis Of Slow-Slip Tremor Events Along The Cascadia Subduction Zone Using Continuous Gps Array Data, James Steven Chapman

All Master's Theses

Seismic hazards poised to cities by subduction zones are strongly controlled by fault slip along the deeper extent of the two plate interaction closest to population densities. In Cascadia, where Mw=9 size events are known to occur from a variety of sources, modeling of leveling data has suggested that the region of maximum slip lies well offshore and diminishes rapidly inland. However, over two dozen slow slip distributions have been imaged using Global Positioning System (GPS) along the lower reaches of the northern Cascadia locked zone between 30 and 40 km in depth. Averaged over many episodic tremor and slip …

Petrogenetic Processes Characterizing The Mount Bachelor, Oregon Magmatic System: Open- Versus Closed-System Processes, Sara Elizabeth Johnson

All Master's Theses

Mount Bachelor volcanic chain (MBVC), located in central Oregon, is one of the larger basalt and basaltic-andesite edifices in central Oregon. Preliminary studies have defined how eruptions have changed composition with time, but a detailed assessment of magma chamber processes has not been conducted. To gain a more thorough understanding of the magmatic processes that have contributed to the observed compositional evolution, this study focuses on one of four eruptive episodes, specifically episode III, the most voluminous episode of the four. Magmatic processes are assessed by focusing on both whole-rock and single crystal data.

The geochemistry and textural diversity of …

Comparison Of Landslides And Their Related Outburst Flood Deposits, Owyhee River, Southeastern Oregon, Shannon Marian Othus

All Master's Theses

Numerous landslides have entered the Owyhee River canyon north of Rome, Oregon. As the river flows through different lithologic units, the style of mass wasting changes from large slump events and small rock falls to large earthflows. The change in mechanism of mass wasting from upstream to downstream seems to depend on several factors: (1) the ratio of the basalt cap to the exposed underlying sediments, (2) the composition of underlying sediments, (3) the canyon geometry, and (4) the extent and frequency of mass wasting. All three mechanisms of mass wasting have the ability to block the river channel and …

The 2004 And 1861 Tsunami Deposits On Simeulue Island, Western Sumatra, Katherine Frances Whitlow

All Master's Theses

Megathrust earthquakes and associated tsunamis along the subduction zone along western Sumatra represent a significant seismic hazard that is not well understood. I present the results of mapping, paleoseimologic, and geochronologic studies of tsunami deposits exposed on Simeulue Island, western Sumatra, to document the timing of past tsunamis. Three field sites were targeted to conduct these studies: Inor, Busong Bay, and Langi Bay. Stratigraphic relationships, geochronologic data, and grain size analyses from these field sites show evidence of a tsunami that occurred in 1861 following a Mw ~8.5 earthquake. A wood fragment collected from an excavation at Inor yielded an …

Climate Change And Freshwater Resources, Robert H. Abrams, Noah D. Hall, Bret B. Stuntz

Journal Publications

Earth's climate is warming. This is the unequivocal conclusion of climate scientists. Despite the complexities of climatology, certain consistent trends emerge with implications for water availability: as the world gets warmer, it will experience increased regional variability in precipitation, with more frequent heavy precipitation events and more susceptibility to drought. These simple facts will have a profound impact on freshwater resources throughout the United States, as the warmer climate will reduce available water supplies and increase water demand. Unfortunately, current water law and policy are not up to the new challenges of climate change and resulting pressures on freshwater resources. …

Origin Of Conductive Surface Layer In Annealed Zno, David C. Look, B. Claflin, Helen Smith

Mathematics and Statistics Faculty Publications

The highly conductive surface layers found in nearly all as-grown or annealed bulk ZnO wafers are studied by temperature-dependent Hall-effect and secondary-ion mass spectroscopy (SIMS) measurements. In this work, we have used annealing in N₂ at 900 degrees C, and forming gas (5% H₂ in N₂) at 600 degrees C, to cause a large enough surface conduction that SIMS measurements can be reliably employed. The increased near-surface donor density, as determined from two-layer Hall-effect modeling, is consistent with an increased near-surface concentration of Al, Ga, and In atoms, resulting from diffusion. There is no evidence for …