no / The shear and extensional properties of injection moulding grade hydroxyapatite¿polyethylene composites developed for orthopaedic applications have been studied. The composite was prepared without processing aids owing to concerns over the potential biological responses to such additives. The composite containing 20 vol.-% hydroxyapatite filler showed typical pseudoplastic behaviour. However, that containing 40 vol.-% hydroxyapatite filler tended to exhibit yield. The Maron¿Pierce equation was found to be useful in predicting the viscosities of the composite systems. The activation energy of the composite and the unfilled polymer were equal, indicating that the 20 vol.-% system exhibits the same flow mechanism as the unfilled polymer. A qualitative assessment of extensional properties was made following Cogswell's method. The extensional stress of the unfilled polymer decreases with increasing temperature whereas the composites behave in a complex manner. For all the systems the Trouton ratios tend to increase with apparent shear rates. The Trouton ratio also indicates that at higher temperatures the flow of these composites is dominated by extensional properties.

Yes / A compact dielectric resonator antenna (DRA) for wideband applications is proposed. Two cylindrical dielectric resonators which are asymmetrically located with respect to the center of a rectangular coupling aperture are fed through this aperture. By optimizing the design parameters, an impedance bandwidth of about 29%, covering the frequency range from 9.62 GHz to 12.9 GHz, and a gain of 8 dBi are obtained. Design details of the proposed antenna and the results of both simulation and experiment are presented and discussed.

No / This paper investigates into the performance and load management of web servers that are deployed in commercial websites. Such websites offer various services such as flight/hotel booking, online banking, stock trading, and product purchases among others. Customers are increasingly relying on these round-the-clock services which are easier and (generally) cheaper to order. However, such an increasing number of customers' requests makes a greater demand on the web servers. This leads to web servers' overload and the consequential provisioning of inadequate level of service. This paper addresses these issues and proposes an admission control scheme which is based on the class-based priority scheme that classifies customer's requests into different classes. The proposed scheme is formally specified using -calculus and is implemented as a Java-based prototype system. The prototype system is used to simulate the behaviour of commercial website servers and to evaluate their performance in terms of response time, throughput, arrival rate, and the percentage of dropped requests. Experimental results demonstrate that the proposed scheme significantly improves the performance of high priority requests but without causing adverse effects on low priority requests.

Yes / This paper presented a new circular polarization reconfigurable antenna for 5G wireless communications. The antenna, containing a semicircular slot, was compact in size and had a good axial ratio and frequency response. Two PIN diode switches controlled the reconfiguration for both the right-hand and left-hand circular polarization. Reconfigurable orthogonal polarizations were achieved by changing the states of the two PIN diode switches, and the reflection coefficient |S11| was maintained, which is a strong benefit of this design. The proposed polarization-reconfigurable antenna was modeled using the Computer Simulation Technology (CST) software. It had a 3.4 GHz resonance frequency in both states of reconfiguration, with a good axial ratio below 1.8 dB, and good gain of 4.8 dBic for both modes of operation. The proposed microstrip antenna was fabricated on an FR-4 substrate with a loss tangent of 0.02, and relative dielectric constant of 4.3. The radiating layer had a maximum size of 18.3 18.3 mm2, with 50 W coaxial probe feeding. / European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424.

Yes / An offset quad-element, two-port, high-gain, and multiband multiple-input multiple-output (MIMO) planar antenna based on a log-periodic dipole array (LPDA) for Ku/K-band wireless communications is proposed, in this paper. A single element antenna has been designed starting from Carrel's theory and then optimized with a 50-Ω microstrip feed-line with two orthogonal branches that results mainly in a broadside radiation pattern and improves diversity parameters. For experimental confirmation, the designed structure is printed on an RT-5880 substrate with a thickness of 1.57 mm. The total substrate dimensions of the MIMO antenna are 55 × 45 mm2. According to the measured results, the designed structure is capable of working at 1.3% (12.82-12.98 GHz), 3.1% (13.54-13.96 GHz), 2.3% (14.81-15.15 GHz), 4.5% (17.7-18.52 GHz), and 4.6% (21.1-22.1 GHz) frequency bands. Additionally, the proposed MIMO antenna attains a peak gain of 4.2-10.7 dBi with maximum element isolation of 23.5 dB, without the use of any decoupling structure. Furthermore, the analysis of MIMO performance metrics such as the envelope correlation coefficient (ECC) and mean effective gain (MEG) validates good characteristics, and field correlation performance over the operating band. The proposed design is an appropriate option for multiband MIMO applications for various wireless systems in Ku/K-bands.

To fully optimize the value of material produced from a log requires information about the log's internal defects prior to log breakdown. Studies have shown that a 7 to 21 percent improvement in log value recovery can be achieved if the location and identity of internal defects are known. Recent developments in advanced nondestructive testing methods such as CT and MRI offer, for the first time, the possibility of finding internal defects in logs prior to breakdown. Our ability to detect and recognize defects using this data depends Critically on our understanding of wood structure and our ability to devise reliable method for automated image interpretation. While a lot of work has gone into demonstrating that certain types of defects manifest themselves in such sensor imagery, there has not been a systematic approach toward making the automatic inspection of logs a practical reality. This dissertation describes work aimed at creating a viable automated technology for locating and identifying log defects. The imaging modality used in this dissertation is CT. An important first step is to establish a data base of imagery and the ground truth information to determine how the various defects manifest themselves in this imagery. The second step is to study defect characterization and determine exactly which defects are detectable. The final step is to develop a basic method of approach to automated image analysis. A data base has been created from two hardwood species. It is representative of hardwood logs in the sense that it contains almost all the major defects. Visual inspection and analysis of these CT images have shown that most defects manifest themselves in CT imagery. These defects can be detected by features such as intensity, 3-d shape, and texture. As a means of automated image analysis, a knowledge-based vision system has been developed. It consists of three components: a data acquisition unit, an image segmentation module, and scene analysis module. A 3-d adaptive LS filter has been developed in the segmentation module that is efficient in removing annual rings while preserving other needed high frequency detail. Images are segmented using a multiple threshold scheme and regions are grouped using a 3-d connected volume growing algorithm. To represent the 3-d nature of wood defects, a set of basic features have been defined and used to design a set of hypothesis tests. These features seem to be adequate for defect recognition. To cope with imprecision and ambiguity the Dempster-Shaffer model for knowledge representation is used in the vision system. As a viable alternative to Bayesian-based theory, the Dempster's method of evidential reasoning is employed that uses previously unavailable information such as the amount of ignorance and ambiguity a hypothesis exhibits. As such, the proposed vision system seems to be able to recognize a number of hardwood defects. This dissertation also explores wood texture as an additional feature in defect recognition, and contributes the first application of robust Spatial AutoRegressive modeling to wood texture analysis. Based on a correlation measure, two simple but efficient texture discrimination schemes are proposed. Incorporating a texture test in the scene analysis should improve the vision system's recognition power. As a pilot research, this dissertation has explored a number of important issues in creating a vision system for automated log inspection. Clearly, more work is needed to make the system more robust with additional species. Nevertheless, preliminary results seem to indicate that a machine vision system for automated hardwood log inspection can be developed. / Ph. D.

The synthesis of epoxide containing block and alternating copolymers has been investigated in this research. Poly(ethylene oxide-2-ethyl-2-oxazoline) (PEO) copolymers have been synthesized with poly(ethylene oxide) macroinitiators ranging from O.75K-40K. Monohydroxy functionalized PEO oligomers have been synthesized with potassium tert-butoxide as an initiator in tetrahydrofuran, and in the bulk. The PEO oligomers were reacted with 4-(chloromethyl) benzoyl chloride to yield a 4-(chloromethyl) benzoate functionalized PEO oligomer quantitatively. This oligomer was further reacted in the melt with sodium iodide to result in 4-(iodomethyl) benzoate functionalized PEO oligomers. The iodo adduct (macroinitiator) initiated the polymerization of 2-ethyl-2-oxazoline, the second block of the diblock copolymer. The formation of the poly ( ethylene oxide-2-ethyl- 2-oxazoline) copolymer resulted in materials ranging from 20 - 80 weight percent poly(2-ethyl-2-oxazoline) (PEOX). These materials were water soluble with PEOX as a strong hydrogen bonding block in the copolymer. The diblock copolymers may have potential uses in particle stabilization, and coating applications. / Ph. D.

Wood pulp mill effluents continue to attract much attention due to environmental consequences. However, in comparison, very little work has been published on wood pulp extracts themselves. In this investigation, chemithermomechanical (CTMP) pulps as well as Kraft (BKP) pulps were Soxhlet extracted with solvents of different polarity. These two types of pulp extracts were then compared qualitatively using GC-FID and GC-MSD as well as quantitatively based on the percent of extractives obtained. For all the pulps studied, the percent extractives of water > ethyl acetate > cyclohexane. The CTMP extracts exhibited many more components as compared to BKP extracts for all the extractions solvents. The presence of trace chlorinated phenolics in the above wood pulp extracts was also addressed utilizing GC-ECD, GC-EIMS and GC-NCIMS. 4-MCG, 4,5-DCG, 4,5,6-TCG, 3,4,5-TCG, 2,4,6- TCP, 2,3,4,6-TeCP, PCP and 6-MCVN were discovered. Due to a lack of knowledge of the complete history of the wood pulps studied, the exact causes for their discoveries are unknown. Attempts were also made to study the feasibility of Supercritical Fluid Extraction of the above mentioned wood pulps due to the difficulties faced with Soxhlet extractions. The percent extractives obtained using SF-CO₂ and cyclohexane were found to be comparable. / Ph. D.

Traditionally, knowledge management tool design has fit into the repository paradigm: a database of stored information that can be queried by an individual seeking information. These tools often rely on two distinct user groups: those who produce the knowledge and those who seek it. The disparity between these two groups - one group benefiting from the other group's work - is a leading cause of a knowledge management tool's failure. Additionally, knowledge management tools fail because the work processes of target users are not fully understood and therefore not addressed in the tool design. Developing knowledge management tools for educators presents additional obstacles in this already hazardous environment. The traditional impediments found in the development of knowledge management systems, such as trust and incentive concerns, are present along with additional concerns faced by educators such as strict time and resource constraints. And like teaching, educators have different impressions of how knowledge management practices should be done. Therefore, any knowledge management tool for educators must address these obstacles in order to be effective. This research describes the development of an activity-centric knowledge management tool. Activity-centric knowledge management tools avoid the repository paradigm by focusing on the processes in which work is done rather than the storing of information that results from such work. This approach to knowledge management in an educational environment allows teachers to focus on the work involved in teaching rather than knowledge management itself which typically involves added tasks such as entering information into a database. First, I describe current knowledge management practices of teachers by reviewing literature from education and knowledge management as well as interviews and surveys of teachers regarding how they incorporate knowledge management into their teaching practices. Next, I examine the development of the Survey Data Visualization Tool, an activity-based knowledge management tool. Finally, I analyze the use of the Survey Data Visualization Tool by a group of teachers. / Master of Science

Introduction: Mobile health applications (mHealth apps) may support people’s chronic obstructive pulmonary disease (COPD) self-management. Current research has demonstrated the promising effects of mHealth apps for people with COPD but there is still limited information on these apps’ characteristics and qualities, especially those in the public domain. Therefore, there is the need to use a standardized evaluation framework to: 1) describe characteristics and qualities of COPD apps from past studies; 2) characterize the features and qualities of public COPD apps; and 3) determine the appropriateness of public COPD apps from the perspective of clinicians and patients living with COPD. Methods: The mHealth Index and Navigation Database (MIND) framework, an objective evaluation tool was applied across studies. Project 1: A systematic review was conducted, including randomized controlled trials investigating interactive mHealth apps for people living with chronic lung diseases (CLD). Project 2: An evaluation study of the public marketplace (Android and Apple app stores) was conducted. Free mHealth apps created specifically for COPD self-management were included. Project 3: Reviewed COPD apps were presented to stakeholders in an infographic format. A RAND/UCLA Appropriateness Method (RAM) was used to collect feedback from stakeholders on the state of public COPD apps. Results: Many of the COPD apps trialed in past studies have inconsistent reports of their features and qualities, with many publicly unavailable. Most public COPD apps lacked clinical evidence to support their use and have questionable qualities. Stakeholders agreed that public COPD apps were mostly inappropriate but did not dismiss the need to discuss their potential in COPD care plans. Significance: This thesis project advocates for the partnership with multiple heath disciplines and patient-participants for app evaluations to gain stronger understanding of their potential. Future opportunities may include exploring other apps for lung diseases to promote stakeholder engagement throughout the process. / Thesis / Candidate in Philosophy