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The Teaching And Learning Of Word Problems In Beginning Algebra : A Nigerian (Lagos State) Study, Omolola A. Ladele

Theses: Doctorates and Masters

At both the junior and senior secondary school levels in Nigeria, student performance in mathematics examinations has been poor. Within the context of large classes, with inadequate facilities, and teaching and learning in a second language, algebra and algebra word problems are introduced to students during their first year of junior secondary school. The transition from primary school arithmetic to the use of the algebraic letter is challenging to students and it is important that teachers should know the likely difficulties and misconceptions students may have as they begin algebra (Welder, 2012).

In this study, the impact of a teacher …

Tablet Pc Use In Teaching And Learning : A Case Study, Andrew Stewart

Theses: Doctorates and Masters

With the emergence of the use of the traditional (non-touch screen) notebook computer in the classroom, different teaching styles and equipment have been introduced. Teachers have started to use the Notebook PC to support their teaching. They now have the ability to gather and use a far greater range of materials in the classroom with little distraction.

The introduction of the touch screen Tablet PC has brought another dimension to the way technology can be used in the classroom. This study seeks to investigate the ways in which Tablet PC technology has been used to enhance the learning of students …

The Reality Of Reform : Teachers Reflecting On Curriculum Reform In Western Australia, Jessica Lyle

Theses: Doctorates and Masters

Australia is implementing its first national curriculum, the Australian Curriculum, after many years of debate regarding the validity and practicality of such an undertaking. Although it is widely accepted that “the effects of education policies and programs depend chiefly on what teachers make of them” (Cohen & Ball, 1990, p. 233), little is known about teachers’ perceptions of the Australian Curriculum or their prior experiences of mandatory curriculum reform as they begin engaging with this unique reform. To provide a means of exploring these perceptions and experiences, 18 teachers, four Head of Learning Areas (HOLAs) and the principal from a …

Using Semi-Supervised Classifiers For Credit Scoring, Kenneth Kennedy, Brian Mac Namee, Sarah Jane Delany

Articles

In credit scoring, low-default portfolios are those for which very little default history exists. This makes it problematic for financial institutions to estimate a reliable probability of a customer defaulting on a loan. Banking regulation (Basel II Capital Accord), and best practice, however, necessitate an accurate and valid estimate of the probability of default. In this article the suitability of semi-supervised one-class classification algorithms as a solution to the lowdefault portfolio problem are evaluated. The performance of one-class classification algorithms is compared with the performance of supervised two-class classification algorithms. This study also investigates the suitability of oversampling, which is …

Mathematical Self-Efficacy: Addressing The Declining Interest In Engineering Careers, Eileen Goold

Conference Papers

This paper presents the findings of a study investigating whether there is a relationship between students’ experiences with school mathematics and their choice of engineering as a career. The study was inspired by the observation that there is a lacuna in the scholarly literature concerning the nature of mathematics’ role, if any, as a significant cause of the declining number of students entering professional engineering courses. The population of interest in this study comprises professional engineers practising in Ireland. Engineers’ experiences of school mathematics, factors that contributed to their engagement with school mathematics and the impact of their feelings about …

Inverter Performance For Small Wind Turbines When Connected In Paralled With The Low-Voltage Distribution System, Jonathan Blackledge, Eugene Coyle, Derek Kearney, Eamonn Murphy

Articles

Small wind turbines have been installed in urban and turbulent locations with surprisingly poor performance and this has been backed up by data from a trial at the Technological University Dublin. In order to develop the small wind turbine industry a careful examination of assessment methods for the wind resource is required. Small wind turbines connected in parallel with the grid use inverters. As the wind turbine is not always at max output, a Weighted Average Efficiency for wind inverters is proposed. Pitfalls associated with developing an accurate weighted average efficiency for an inverter are identified and this will enable …

Variances In Airflows During Different Ventilation Modes In A Dynamic U-Shaped Cave, Jiří Faimon, Marek Lang

International Journal of Speleology

Airflow dynamics were studied in Císařská Cave (Moravian Karst, Czech Republic) under different seasonal conditions. The dependence of airflows on the difference between external and cave temperatures is nonlinear and roughly obeys the Darcy-Weisbach equation. The upward airflows were found to be systematically higher than the downward airflows under comparable driving forces. The principle reason is nonlinearity between air temperature and air density. U-shaped cave geometry magnifies this effect by feedback between external temperature and airflow driving forces. Whereas this feedback is positive during the upward airflow ventilation mode, it is negative during the downward airflow mode. To discuss the …

Book Review: Trevor Shaw And Alenka Čuk Slovene Caves & Karst, Pictured 1545-1914, Arrigo A. Cigna

International Journal of Speleology

Trevor Shaw and Alenka Čuk.
Slovene Caves & Karst, pictured 1545-1914
Založba ZRC, Ljubljana, 2012.
ISBN 978-961-254-369-3, 230 p. 200x290, 258 b/w and colour illustrations, paper cover, € 25.00

Full Issue 42(2)

International Journal of Speleology

All articles in Volume 42 Issue 2. Does not include cover image.

Layer-Bounding Surfaces In Stalagmites As Keys To Better Paleoclimatological Histories And Chronologies, Loren Bruce Railsback, Pete D. Akers, Lixin Wang, Genevieve A. Holdridge, Ny Riavo Voarintsoa

International Journal of Speleology

Petrographic recognition of layer-bounding surfaces in stalagmites offers an important tool in constructing paleoclimate records. Previous petrographic efforts have examined thickness of layers (a possible proxy for annual rainfall) and alternation of layers in couplets (a possible indicator of seasonality). Layer-bounding surfaces, in contrast, delimit series of layers and represent periods of non-deposition, either because of exceptionally wet or exceptionally dry conditions.

Two types of layer-bounding surfaces can be recognized according to explicitly defined petrographic criteria. Type E layer-bounding surfaces are surfaces at which layers have been truncated or eroded at the crest of a stalagmite. Keys to their recognition …

Advances In Blind Source Separation, Christopher Osterwise

Doctoral Dissertations

"Blind Source Separation (BSS) is a classic problem that attempts to separate unknown sources from observed mixtures. A common framework of this is the Cocktail Party problem, where multiple individuals speaking in a noisy room are recorded by a configuration of microphones, with the challenge being to split the observed signals into individual conversations. This dissertation covers the evaluation of an existing algorithm known as Cascaded ICA with Intervention Alignment (CICAIA), the establishment of a new parameter for characterizing blind mixtures, and three new algorithms, of which two are capable of separating any number of sources given more microphones than …

Effect Of Dense Heat Exchanging Internals On The Hydrodynamics Of Bubble Column Reactors Using Non-Invasive Measurement Techniques, Mohammed Khloofh Al Mesfer

Doctoral Dissertations

"Given their efficiency and capital cost reduction, bubble/slurry bubble column reactors are the reactors of choice for Fischer-Tropsch (FT) synthesis, offering clean alternative fuels and chemicals. FT synthesis is an exothermic process that requires many heat exchanging tubes in order to remove heat efficiently and maintain the desired temperature and isothermal operating condition. The impact of the heat exchanging tubes (internals) on the hydrodynamics is not fully understood. Reliably designing and scaling up bubble column reactors requires proper understanding of hydrodynamics, as well as heat and mass transfer parameters.

The main objective of this work is to advance the understanding …

Modeling And Analysis Of Dynamic Behavior Of Adsorption Stratified Column Beds Packed With Partially Fractal Porous Adsorbent Particles, Min Li

Doctoral Dissertations

"In this work novel porous adsorbent media having partially fractal structures and stratified packed-beds are constructed and their dynamic performance with respect to their adsorptive capacity through the construction and solution of rigorous models is studied. The results show that conventional columns packed with partially fractal porous adsorbent particles provide larger breakthrough times and dynamic utilization of the adsorptive capacity of the column when compared with those of conventional columns employing conventional adsorbent particles which do not possess a partially fractal structure. Furthermore, stratified column beds exhibit superior species separation performance than conventional columns when they are packed with either …

Source Reconstructions For Ic Radiated Emissions Based On Magnitude-Only Near-Field Scanning, Ji Zhang

Doctoral Dissertations

"In this dissertation, a source reconstruction method is proposed to model the emission behavior of an IC by using magnitude-only information during near-field scanning. The phase-retrieval is accomplished during the back-forth iterations between two scanning planes of different heights. The magnitudes of fields on two planes of different heights are recorded and used to constrain the amplitude of the calculated fields during iterations. Three essential transformations among dipoles and fields are continued at each iteration step, until the convergence condition is achieved. The proposed algorithm has been verified by using a set of dipole-array as the original emitting sources, and …

Topics In Voice Echo Cancellation, Pratik Vijay Shah

Doctoral Dissertations

"Acoustic echo cancellation (AEC) is a well studied problem. The underlying assumption in most echo cancellation solutions is that the echo path following the reference signal is completely linear. However, in many handheld devices, the echo path following the reference signal is nonlinear. The reason for this nonlinearity in the echo path is the use of smaller and cheaper loudspeakers. In order to cut the manufacturing cost, device manufactures use cheaper loudspeakers such that they satisfy the carrier specifications. Such loudspeaker can be easily over driven in to their nonlinear region and thus add nonlinearities to the downlink path. This …

Bio-Inspired Design, Fabrication And Testing Of Bipolar Plates For Pem Fuel Cells, Nannan Guo

Doctoral Dissertations

"The flow field of a bipolar plate distributes reactants for polymer electrolyte membrane (PEM) fuel cells and removes the produced water from the fuel cells. It greatly influences the performance of fuel cells, especially the concentration losses. Two approaches were developed to improve flow field designs in this dissertation. One is inspired by the biological circulatory structures and called bio-inspired designs, which have great potential to transport reactant efficiently and hence improve fuel cell performance. Another way is using a network-based optimization model to optimize the conventional flow field configurations, i.e., pin-type, parallel and serpentine designs, to improve flow distributions …

Polybenzoxazine Aerogels: Synthesis, Characterization, Conversion To Porous Carbons, And Energetic Composites, Shruti Mahadik-Khanolkar

Doctoral Dissertations

"Aerogels are nanoporous, low-density bulk objects, consisting of three-dimensional assemblies of nanoparticle. Structured similarly, polymeric aerogels are emerging as a mechanically strong alternative to traditional silica aerogels, which are fragile. Amongst polymeric aerogels, those based on polybenzoxazine (PBO - a type of phenolic resin), are extremely robust and comprise an economic alternative to resorcinol-formaldehyde aerogels, also a class of phenolic resins, as the main source of carbon aerogels. The drawback of the PBO chemistry has been the long (days) processing time at high-temperatures (>130 ºC). Herewith, we have developed an energy- and time-efficient process to PBO aerogels by inducing …

Study Of Artificially Disordered Optical Fibers, Herath Mudiyanselage Sumudu Rasika Kumari Herath

Doctoral Dissertations

"Light transmission through photo-sensitive multi-mode fibers (MMF) with controlled volume disorder is investigated. Experiment shows that a segment of disordered MMF as short as 10 cm is sufficient to distribute power uniformly over all co-propagating modes and the intensity at the output surface of the fiber follows the Rayleigh negative exponential function. To explain the experimental findings, a comprehensive theoretical model is developed with three main results. First, statistical properties of all components of the dielectric tensor are obtained and analyzed in the framework a microscopical model of photo-sensitivity in a germano-silicate glasses. Secondly, it is shown that induced birefringence …

Observability-Enhanced Dual-Filter Design For Attitude Estimation With Minimum Observations, Jason D. Searcy

Doctoral Dissertations

"Determining spacecraft attitude in real time using only magnetometer data presents a challenging filtering problem. A flexible and computationally efficient method for solving the spacecraft attitude using only an inexpensive and reliable magnetometer would be a useful option for satellite missions, particularly those with modest budgets. The primary challenge is that magnetometers only instantaneously resolve two axes of the spacecraft attitude. Typically, magnetometers are used in conjunction with other sensors to resolve all three axes. However, by using a filter over an adequately long orbit arc, the magnetometer data can yield full attitude, and in near real time. The method …

Characterization Of Nano-Scaled Metal-Hydrides Confined In Nano-Porous Carbon Frameworks, David Edward Peaslee

Doctoral Dissertations

"Metal hydrides are currently being studied to provide hydrogen for use in fuel cells and for transportation applications. Hydrogen can be stored in chemical compounds at higher density and lower volume than liquid H₂ or compressed gas. Thermodynamic properties of metal hydrides differ between bulk and nano-sized particles. Many metal hydrides with useful volumetric and gravimetric capacities have high decomposition temperatures, but when placed in nano-sized frameworks (or templates) desorption and adsorption temperatures can be fine-tuned to meet engineering requirements for real-world systems. Additionally, some metal hydrides have shown a change in the decomposition pathway when infiltrated into these frameworks, …

Privacy-Preserving Friend Recommendations In Online Social Networks, Bharath Kumar Samanthula

Doctoral Dissertations

"Online social networks, such as Facebook and Google+, have been emerging as a new communication service for users to stay in touch and share information with family members and friends over the Internet. Since the users are generating huge amounts of data on social network sites, an interesting question is how to mine this enormous amount of data to retrieve useful information. Along this direction, social network analysis has emerged as an important tool for many business intelligence applications such as identifying potential customers and promoting items based on their interests. In particular, since users are often interested to make …

Model Based Fault Diagnosis And Prognosis Of Nonlinear Systems, Hasan Ferdowsi

Doctoral Dissertations

"Rapid technological advances have led to more and more complex industrial systems with significantly higher risk of failures. Therefore, in this dissertation, a model-based fault diagnosis and prognosis framework has been developed for fast and reliable detection of faults and prediction of failures in nonlinear systems. In the first paper, a unified model-based fault diagnosis scheme capable of detecting both additive system faults and multiplicative actuator faults, as well as approximating the fault dynamics, performing fault type determination and time-to-failure determination, is designed. Stability of the observer and online approximator is guaranteed via an adaptive update law. Since outliers can …

Regional Geomorphic Analysis And Gis Susceptibility Mapping Of Landslides In The Blue Nile And The Tekeze River Basins Of Ethiopia, Elamin Hassan Dai Ismail

Doctoral Dissertations

"The Plateau region of Ethiopia lies within a seismically active continental extensional regime, which is being rapidly incised by the Blue Nile and the Tekeze Rivers. Extremely large landslides pose serious hazards in this highly populated region (>27 million), which is in the process of developing its hydrologic resources. This research sought to develop cost-effective methods to compile regional landslide inventory and landslide susceptibility maps, using geomorphic tools and GIS technologies. This work also sought to evaluate the relationships between landslide dams and knickpoints, caused by channel bed incision from those caused by slope failures, by utilizing identified knickpoints …

Numerical Analyses Of Long Carbon Fiber Reinforced Concrete Panels Exposed To Dynamic Loading, Zahra Sadat Tabatabaei

Doctoral Dissertations

"The purpose of this research was to evaluate impact and blast performance of long carbon fiber reinforced concrete experimentally and numerically. Experimental tests were conducted on plain concrete (PC), reinforced concrete, and four different types of long carbon fiber reinforced concrete (LCFRC). The results from each test were then compared to one another. This comparison indicates that adding long carbon fibers to concrete both increases the post-cracking behavior of concrete and decreases the spalls in either an impact or blast test. Among all of the fibers tested, Fiber Type B3 outperformed the other fibers, absorbing more energy during impact. Numerical …

Enamel Coated Steel Reinforcement For Improved Durability And Life-Cycle Performance Of Concrete Structures: Microstructure, Corrosion, And Deterioration, Fujian Tang

Doctoral Dissertations

"This study is aimed (a) to statistically characterize the corrosion-induced deterioration process of reinforced concrete structures (concrete cracking, steel mass loss, and rebar-concrete bond degradation), and (b) to develop and apply three types of enamel-coated steel bars for improved corrosion resistance of the structures. Commercially available pure enamel, mixed enamel with 50% calcium silicate, and double enamel with an inner layer of pure enamel and an outer layer of mixed enamel were considered as various steel coatings. Electrochemical tests were respectively conducted on steel plates, smooth bars embedded in concrete, and deformed bars with/without concrete cover in 3.5 wt.% NaCl …

Synthetic Aperture Radar-Based Techniques And Reconfigurable Antenna Design For Microwave Imaging Of Layered Structures, Mojtaba Fallahpour

Doctoral Dissertations

"In the past several decades, a number of microwave imaging techniques have been developed for detecting embedded objects (targets) in a homogeneous media. New applications such as nondestructive testing of layered composite structures, through-wall and medical imaging require more advanced imaging systems and image reconstruction algorithms (post-processing) suitable for imaging inhomogeneous (i.e., layered) media. Currently-available imaging algorithms are not always robust, easy to implement, and fast. Synthetic aperture radar (SAR) techniques are some of the more prominent approaches for image reconstruction when considering low loss and homogeneous media. To address limitations of SAR imaging, when interested in imaging an embedded …

A New Versatile Electronic Speckle Pattern Interferometer For Vibration Measurements, Viswanath Bavigadda

Doctoral

Electronic speckle pattern interferometry (ESPI) has been widely used for vibration amplitude and phase measurements. Conventional ESPI systems are bulk and expensive and need careful alignment of all the optical components which is a time consuming task. To overcome these problems alternative compact ESPI systems were developed using fibre-optical components or holographic optical elements (HOEs). The fibre-optic based ESPI systems suffer from random phase fluctuations induced by environmental temperature changes. Hence HOEs can be used as more powerful alternative optical elements to design ESPI systems. The time average ESPI method is widely used for vibration studies. The time average method …

Integrable Systems As Fluid Models With Physical Applications, Tony Lyons

Doctoral

In this thesis we begin with the development and analysis of hydrodynamical models as they arise in the theory of water waves and in the modelling of blood flow within arteries. Initially we derive three models of hydrodynamical relevance, namely the KdV equation, the two component Camassa-Holm equation and the Kaup-Boussinesq equation. We develop a model of blood flowing within an artery with elastic walls, and from the principles of Newtonian mechanics we derive the two-component Burger's equation as our first integrable model. We investigate the analytic properties of the system briefly, with the aim of demonstrating the phenomenon of …

The Turning, Stretching And Boxing Technique: A Direction Worth Looking Towards, Mark Dunne

Doctoral

3D avatar user interfaces (UI) are now used for many applications, a growing area for their use is serving location sensitive information to users as they need it while visiting or touring a building. Users communicate directly with an avatar rendered to a display in order to ask a question, get directions or partake in a guided tour and as a result of this kind of interaction with avatar UI, they have become a familiar part of modern human-computer interaction (HCI). However, if the viewer is not in the sweet spot (defined by Raskar et al. (1999) as a stationary …

Octree-Based Indexing For 3d Point Clouds Within An Oracle Spatial Dbms, Bianca Schoen-Phelan, Abu Saleh Mohammad Mosa, Debra Laefer, Michela Bertolotto

Articles

A large proportion of today’s digital data has a spatial component. The storage and effective 10 management of such data poses particular challenges. Nowhere is this truer than with Light De-11 tection and Ranging (LiDAR), where datasets of even small geographic areas may contain sever-12 al hundred millions points. Currently available spatial information systems do not provide suita-13 ble support for 3D data. As a consequence, while a specific system can be used to store the data, 14 another has to be used to process it. Typically several software applications are used to analyze 15 and process LiDAR data, requiring …