Reflection cracking is one of the main distresses in hot-mix asphalt (HMA) overlays. It has been a serious concern since early in the 20th century. Since then, several models have been developed to predict the extent and severity of reflection cracking in HMA overlays. However, only limited research has been performed to evaluate and calibrate these models. In this dissertation, mechanistic-based models are calibrated to field data of over 400 overlay test sections to produce a design process for predicting reflection cracks. Three cracking mechanisms: bending, shearing traffic stresses, and thermal stress are taken into account to evaluate the rate of growth of the three increasing levels of distress severity: low, medium, and high. The cumulative damage done by all three cracking mechanisms is used to predict the number of days for the reflection crack to reach the surface of the overlay. The result of this calculation is calibrated to the observed field data (severity and extent) which has been fitted with an S-shaped curve. In the mechanistic computations, material properties and fracture-related stress intensity factors are generated using efficient Artificial Neural Network (ANN) algorithms. In the bending and shearing traffic stress models, the traffic was represented by axle load spectra. In the thermal stress model, a recently developed temperature model was used to predict the temperature at the crack tips. This process was developed to analyze various overlay structures. HMA overlays over either asphalt pavement or jointed concrete pavement in all four major climatic zones are discussed in this dissertation. The results of this calculated mechanistic approach showed its ability to efficiently reproduce field observations of the growth, extent, and severity of reflection cracking. The most important contribution to crack growth was found to be thermal stress. The computer running time for a twenty-year prediction of a typical overlay was between one and four minutes.

This research considered overlay districts as one technique to supersede Euclidian zoning, broaden its application to regulate land use, promote retention of industrial space and improve job development. Since the 1950s America has been losing industrial or manufacturing jobs and space in cities throughout the country. Moreover economic indicators following the great recession of 2007 reflected an aggregate loss of 8 million jobs, and an increase in national and regional industrial vacancy rates, which have recently, began to decline. Some researchers and local officials argue that industrial space, market and job losses were affected in part by less-protective, inflexible and/or inadequate Euclidian zoning regulations. In addition, it is argued that inadequate industrial zoning has contributed to the loss of investment of financial and human capital in local communities. Traditional zoning known as Euclidian zoning is a predominant form of land use control in the U.S. Today, it is a technique designed to separate and protect adjacent uses from encroachment, incompatibility and nuisances. The primary goal of this study was to explore and describe how overlay districts (located in inner urban/inner-ring suburbs) supersede Euclidean zoning, promote economic development and affect the creation of jobs through industrial development and\or urban redevelopment. Theoretical constructs informing this research included zoning, land use, local economic development and location theories. The fundamental research question asked is: "Do overlays protect industrial land and jobs better than Euclidian zoning and does the protection facilitate greater confidence in industrial investment? To address the research question of this dissertation and analyze data, a mixed methods research design was employed. The design consisted of Internet research, a qualitative multiple (six) case-study analysis, interviews of agency personnel, field reconnaissance, and a sample survey of implementing agencies (which used a data base of over 2700 ordinances from the Municipal Code Corporation). The conclusion of this study is that overlays protect industrial land and jobs better than Euclidian zoning and the protection does facilitate greater confidence in industrial investment. Manufacturers and other industrial oriented-users have located in EDODs and have in some cases lobbied the local governments for continuation of the district. Jobs have also been added in consecutive years within key EDODs. Moreover, newly established EDODs have been used to target investments in infrastructure and incentives to underwrite the cost of industrial development. Policy implications of this study will inform planners regarding the need for industry and manufacturing uses to create sustainable employment within their communities.

There is little evidence that Health Technology Assessment (HTA) is much used in dentistry. Dental implant technology is an example of innovative oral health technology. The objectives of this research were to gather the evidence needed for the assessment of overdenture implant treatment so that both patients and dental practitioners can make informed decisions about this technology. These objectives included 1) investigating what types of dental clinicians adopt and provide dental implants 2) determining the effect of the clinicians' experience in the provision of implant supported prostheses and 3) measuring the patients' preference in provision of mandibular 2-implants overdenture technology. / For the first part, a cross-sectional survey was sent to all licensed Canadian Dentists to measure the adoption and provision of implant technology. For the second part, we used the data on the first 140 edentulous elders who were enrolled in a randomized controlled clinical trial to compare the effects of mandibular conventional (CD) and 2-implant overdentures (IOD) on nutrition. The change in patient ratings of satisfaction after treatment, laboratory costs and the number of unscheduled visits were compared. For the last part, edentulous elders (N=36) who were wearing maxillary dentures and either a mandibular conventional denture (CD, n=13) or a two-implant overdenture (IOD, n=23) participated in this study. Participants' preference was measured during a 20-minute interview. / Multivariate regression analysis on the data from the first part of the study shows that the Dentist's gender, province of practice, specialty, and whether they practice alone or in association with other practitioners, are significantly associated with the adoption of implant technology (p<0.05). It is also shown that there was no difference in satisfaction scores for either prosthesis between the groups treated by experienced specialists or new dentists. Furthermore, it is shown that IOD wearers were willing to pay three times more than the current cost of conventional dentures for implant prostheses (p<0.05). / Overall, the results of this study 1) inform decision makers on what types of clinicians provide implant technology and 2) suggest that, with minimal training, all dental clinicians irrespective of their specialty, can provide successful implant overdenture prostheses that edentulous patients are willing to pay for.

Microstructural comparison of the isothermal oxidation performance of an experimental Ni-5Cr-15Al overlay coating applied to CMSX-4 and CMSX-486 was performed at 1100 ℃. High temperature oxidation was carried out in a box furnace for a maximum duration of 192 hrs. Samples were periodically removed and the oxide, coating and substrates microstructurally analyzed using SEM, EDS and XRD equipment. Uncoated CMSX-4 and CMSX-486 were also oxidized using the same conditions in an attempt to understand how the coating affected oxidation performance based on microstructural changes. Results show that both CMSX-4 and CMSX-486 have unacceptable oxidation characteristics in the un-coated condition, where CMSX-486 had significantly better performance than CMSX-4. However, in the coated condition, both CMSX-4 and CMSX-486 had no significant difference in oxidation performance. It was found, in the un-coated and coated conditions, that the role of Hf in CMSX-486 played a significant role in determining oxidation performance of the material.

<p>Delivering content of interest to clients is one of the most important tasks of the Internet </p><p>and an everlasting research question of today's networking. Content distribution networks(CDNs) </p><p>emerged in response to the rising demand of content providers to deliver contents to clients efficiently, </p><p>reliably, and securely at relatively low cost.</p><p>This dissertation explores how CDNs can achieve major performance benefits by adopting better </p><p>caching strategies without changing the network, or by collaboration with ISPs and taking advantage of their </p><p>better knowledge of network status and topology. It discusses the emerging trends of hybrid CDN architectures </p><p>and solutions to reliability problems introduced by them. Finally, it demonstrates how CDNs could better </p><p>protect both content providers and consumers from attacks and other malicious behaviors.</p> / Dissertation

The constant growth in network communications technologies and the emergence of Service Specific Overlay Networks (SSONs), coupled with the rapid development of multimedia applications make the management of such technologies a major challenge. This thesis investigates the SSONs management problem and proposes an autonomic architecture, a self-organizing and self-adapting algorithm, and a utility function for monitoring the Quality of Experience (QoE) of IPTV streams in SSONs. First, we examine the different issues stemming from the autonomic management of SSONs and identify the limitations of existing approaches. We then propose an architecture to ease the management of SSONs by incorporating autonomic computing principles to make SSONs acquire self-management capabilities. The proposed architecture introduces autonomic control loops that continuously monitor network components and analyze the gathered data. An Autonomic System (AS) is comprised of one or more Autonomic Managers (AM) which take control of managing other elements in the network. The proposed architecture highlights the different components of an AM and identifies its purpose. The distributed nature of the proposed architecture avoids limitations of centralized management solutions. We then propose a scheme to allow AMs to emerge among the set of nodes in the network as the most powerful ones in terms of different factors, including processing capabilities and stability. Using a self-organizing and self-adapting distributed protocol, each node in the overlay selects an appropriate AM to report to so that sensed data is delivered error-free, and in a timely manner, while the load is distributed over the AMs. Finally, we propose a utility function to monitor the quality of IPTV streams by predicting QoE based on statistical Quality of Service (QoS) information. The proposed function is simple and does not require high processing power. It allows the QoE of IPTV users to be monitored in real-time by the AMs, so that quality degradations are accurately identified and adaptation mechanisms are triggered at the right moment to correct issues causing degradations. Theoretical analysis and simulations studies are presented to demonstrate the performance of the proposed schemes.

Microstructural comparison of the isothermal oxidation performance of an experimental Ni-5Cr-15Al overlay coating applied to CMSX-4 and CMSX-486 was performed at 1100 ℃. High temperature oxidation was carried out in a box furnace for a maximum duration of 192 hrs. Samples were periodically removed and the oxide, coating and substrates microstructurally analyzed using SEM, EDS and XRD equipment. Uncoated CMSX-4 and CMSX-486 were also oxidized using the same conditions in an attempt to understand how the coating affected oxidation performance based on microstructural changes. Results show that both CMSX-4 and CMSX-486 have unacceptable oxidation characteristics in the un-coated condition, where CMSX-486 had significantly better performance than CMSX-4. However, in the coated condition, both CMSX-4 and CMSX-486 had no significant difference in oxidation performance. It was found, in the un-coated and coated conditions, that the role of Hf in CMSX-486 played a significant role in determining oxidation performance of the material.

Publish/Subscribe (in short pub/sub) allows clients that share common interest communicate in an asynchronous and loosely-coupled fashion. This paradigm is adopted by many distributed event-driven applications such as social networking services, distributed business processes and cyber-physical systems. These applications cannot afford to have the underlying pub/sub substrate perform unreliably, permanently fail or behave arbitrarily as it will cause significant disturbance to stably serving many end-users. Therefore, a research effort on making pub/sub systems resilient against various failures to sustain high quality of service to the clients is imperative. In this thesis, we focus on the overlay of pub/sub brokers that are widely adopted as a popular architecture for large-scale pub/sub systems. Broker overlays can suffer from various issues such as degradation of topology quality, brokers causing transient or permanent benign failures and Byzantine brokers behaving arbitrarily. We aim to make novel research contributions by exploring fundamental techniques that can help the broker overlays maintain functional and non-functional requirements even under the presence of the aforementioned failures and necessary administrative updates. We first build a set of overlay adaptation primitives that re-configure topologies such as shifting links and replicating brokers. These primitives are designed to involve a small local group of brokers in the pub/sub overlays so that the disruption during the execution of large-scale and dynamic changes can be controlled in a fined-grained manner. For the problem of degrading topology quality, automated planning systems are developed to find a sequence of adaptations that would cause minimal disruption to running services. Also, our primitives can be executed on demand to quickly fail-over a crashed broker or off-load congested brokers. In addition, these on-demand primitives can be used to form a group of dynamically replicated brokers that enforce a novel safety measure to prevent Byzantine brokers from sabotaging the pub/sub overlays. Our contributions are evaluated with systematic consideration of various trade-offs between functional and non-functional properties.

Publish/Subscribe (in short pub/sub) allows clients that share common interest communicate in an asynchronous and loosely-coupled fashion. This paradigm is adopted by many distributed event-driven applications such as social networking services, distributed business processes and cyber-physical systems. These applications cannot afford to have the underlying pub/sub substrate perform unreliably, permanently fail or behave arbitrarily as it will cause significant disturbance to stably serving many end-users. Therefore, a research effort on making pub/sub systems resilient against various failures to sustain high quality of service to the clients is imperative. In this thesis, we focus on the overlay of pub/sub brokers that are widely adopted as a popular architecture for large-scale pub/sub systems. Broker overlays can suffer from various issues such as degradation of topology quality, brokers causing transient or permanent benign failures and Byzantine brokers behaving arbitrarily. We aim to make novel research contributions by exploring fundamental techniques that can help the broker overlays maintain functional and non-functional requirements even under the presence of the aforementioned failures and necessary administrative updates. We first build a set of overlay adaptation primitives that re-configure topologies such as shifting links and replicating brokers. These primitives are designed to involve a small local group of brokers in the pub/sub overlays so that the disruption during the execution of large-scale and dynamic changes can be controlled in a fined-grained manner. For the problem of degrading topology quality, automated planning systems are developed to find a sequence of adaptations that would cause minimal disruption to running services. Also, our primitives can be executed on demand to quickly fail-over a crashed broker or off-load congested brokers. In addition, these on-demand primitives can be used to form a group of dynamically replicated brokers that enforce a novel safety measure to prevent Byzantine brokers from sabotaging the pub/sub overlays. Our contributions are evaluated with systematic consideration of various trade-offs between functional and non-functional properties.

Techn. University, Diss., 2007--Darmstadt.