Theses

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  • Temporal patterns and ensemble learning for environmental sound recognition
    Temporal patterns and ensemble learning for environmental sound recognition
    This thesis explores features characterizing the temporal dynamics and the use of ensemble techniques to improve the performances of environmental sound recognition (ESR) system. Firstly, for acoustic scene classification (ASC), local binary pattern (LBP) technique is applied to extract the temporal evolution of Mel-frequency cepstral coefficients (MFCC) features, and the D3C ensemble classifier is adopted to optimize the system performance. The results show that the proposed method achieved a classification improvement of 8% compared to the baseline system. Secondly, a new approach for sound event detection (SED) using Nonnegative Matrix Factor 2- D Deconvolution (NMF2D) and RUSBoost techniques is presented. The idea is to capture the two dimensional joint spectral and temporal information from the time-frequency representation (TFR) while possibly separating the sound mixture into several sources. Besides, the RUSBoost ensemble technique is utilized in the event detection process to alleviate class imbalance in the training data. This method reduced the total error rate by 5% compared to the baseline method.
    Tensor analysis of electroencephalogram signal for localization of event-related potentials
    Tensor analysis of electroencephalogram signal for localization of event-related potentials
    Electroencephalogram (EEG) is widely used for monitoring, diagnosis purposes and also for study of brains physiological, mental and functional abnormalities. EEG is known to be a high-dimensional signal in which processing of information by the brain is reected in dynamical changes of the electrical activity in time, frequency, and space. EEG signal processing tends to describe and quantify these variations into functions with known spatio-temporal-spectral properties or at least easier to characterize. Multi-channel EEG recordings naturally include multiple modes. Matrix analysis, via stacking or concatenating other modes with the retained two modes, has been extensively used to represent and analyze the EEG data. On the other hand, Multi-way (tensor) analysis techniques keep the structure of the data, and by analyzing more dimensions simultaneously, summarize the data into more interpretable components. This work presents a generalized multi-way array analysis methodology in pattern classification systems as related to source separation and discriminant feature selection in EEG signal processing problems. Analysis of ERPs, as one of the main categories of EEG signals, requires systems that can exploit the variation of the signals in different contextual domains in order to reveal the hidden structures in the data. Temporal, spectral, spatial, and subjects/experimental conditions of multi-channel ERP signals are exploited here to generate three-way and four-way ERP tensors. Two key elements of this framework are the Time-Frequency representation (TFR) and CANDECOMP/PARAFAC model order selection techniques we incorporate for analysis. Here, we propose a fully data-driven TFR scheme, via combining the Empirical Mode Decomposition and Reassignment method, which yields a high resolution and cross-term free TFR. Furthermore, we develop a robust and effective model order selection scheme that outperforms conventional techniques in mid and low SNRs (i.e. 0􀀀10 dB) with a better Probability of Detection (PoD) and almost no extra computational overhead after the CANDECOMP/PARAFAC decomposition. ERP tensor can be regarded as a mixture that includes different kinds of brain activity, artifacts, interference, and noise. Using this framework, the desired brain activity could be extracted out from the mixture. The extracted signatures are then translated for different applications in brain-computer interface and cognitive neuroscience.
    Terms of restriction
    Terms of restriction
    "Initially developed by universities and the military, the speed at which the Internet was embraced by the general public during the mid-nineteen-nineties took governments and commercial interests by surprise. It allowed for a new form of discourse, where anyone could log-on and, at no additional cost, enter into conversations and debates with millions of other Internet users. This new medium for communicating information allowed individuals to overcome existing financial and spatial barriers and thereby engage in new forms of critical political dialogue. Internet communities have flourished and existing corporate media companies, experienced at producing and distributing content to audiences of consumers, have had to adapt to audiences that increasingly demand the right to create and distribute content themselves. Many governments, Canada included, have chosen to leave the Internet and its infrastructure largely unregulated, believing that existing legislation would suffice (Canadian Radio Television and Telecommunications Commission. CRTC Won't Regulate the Internet). In contrast to traditional media enterprises already dominated by commercial interests, the Internet seemed to be a medium where commercial and public interests could successfully coexist, and where individuals could engage in critical dialogue, share ideas, and shape discourse and opinions offline as well as online."--Introduction.
    Test Methods For Evaluating The Oxidization Potential Of Sulphide –Bearing Aggregates And Its Effects On Concrete Durability
    Test Methods For Evaluating The Oxidization Potential Of Sulphide –Bearing Aggregates And Its Effects On Concrete Durability
    This research project focuses on the development and validation of test methods to evaluate the potential oxidation of sulphide-bearing aggregates, which can cause severe damage when used in concrete. The mechanism of damage is believed to consist of two parts: (a) the oxidation of sulphide minerals, which results in the formation of ferric hydroxide, and (b) the formation of sulphuric acid, which reacts with calcium hydroxide in concrete leading to an internal sulphate attack. Both parts produce a volume increase, damaging the concrete. A simple, quick and economical test method was developed and used to test thirty-one aggregates with different sulphur content. This test involves soaking the aggregate in an oxidizing agent at room temperature, washing the aggregate on a specific sieve, and drying it at 80°C. The soaking and drying cycle is repeated and the disintegration of the aggregates is measured as % mass loss. The composition of the oxidizing solution was evaluated, and the assessment of the aggregate was related to the presence of iron and sulphur ions in the solution after the test. The aggregate oxidation test developed here is anticipated to be adopted as a screening test method by North American standards due to its simplicity and applicability to a wide range of aggregates. The expansion of recently developed mortar bar samples containing a limited number of aggregates proves that the test can show expansion in aggregates with sulphide as well as high silica content; however, the high-silica aggregate did not show significant expansion in the second stage of the test, unlike the sulphide-bearing aggregates. The test was examined for its ability to evaluate the effects of supplementary cementing materials (SCM`s) on mitigating the damage in mortars containing sulphide-bearing aggregates. The results revealed that extended exposure to the oxidizing agent caused damage in the bar due to reasons other than the oxidation of sulphide phases when SCM with high reactive alumina is used. In addition, the results revealed that silica fume and low-calcium fly ash were effective in mitigating the damage, however, the efficacy of SCM`s is mainly linked to their ability to reduce the penetration of oxidizing agents into the mortar bars. These results need to be validated using field investigations. Concrete samples were tested under different conditions in an attempt to replicate the damage mechanisms in concrete samples under lab conditions. Some of the testing regimes showed promising results and are recommended for future studies.
    Test System Development For The Performance Testing Of Asphalt Containing Different Mineral Fillers
    Test System Development For The Performance Testing Of Asphalt Containing Different Mineral Fillers
    This research project identifies the materials and equipment needed to implement Simple Performance Testing (SPT) on Superpave asphalt mixtures. This project can be used as a guide or manual for others who would like to evaluate the performance of Hot Mix Asphalt (HMA) mixtures. This thesis outlines both physical and mechanical SPT requirements and applies them to the performance testing of asphalt mixtures incorporating different types of mineral fillers. Furthermore, this research evaluates the dynamic modulus of asphalt containing various mineral fillers. The results have shown a small increase in dynamic modulus values when 4% fly ash is used as mineral filler when compared to limestone dust (control mix). Portland cement has also shown an increase in dynamic modulus over the control mix although the increase was less than that observed with the use of fly ash. The higher moduli associated with the use of fly ash can be viewed as beneficial in terms of rutting resistance, but require further investigation for fatigue resistance.
    Testing a model of psychosocial outcomes among adults living with mental illness accessing community-based services
    Testing a model of psychosocial outcomes among adults living with mental illness accessing community-based services
    Psychosocial rehabilitation is an approach to recovery from mental illness that promotes skill development, self-determination, and social interaction. One specific type of psychosocial rehabilitation is the clubhouse model. Progress Place, an accredited clubhouse located in Toronto, Ontario recently developed a realist theory that identifies mechanisms of change that lead to recovery outcomes for members. The purpose of the present study was to measure mechanisms and outcomes quantitatively in order to validate the theory of change for the clubhouse model. A total of 168 members completed a self-report questionnaire measuring mechanism and outcome variables, as well as the effects of length and frequency of involvement. The data was analyzed using a hierarchical regression framework as well as mediation models. Results found a significant relationship between the mechanism and outcome variables. The results provide evidence that there are many mechanisms involved in recovery from severe mental illness.
    Testing and analysis of solder joint reliability for BGA assembly under flexural loading
    Testing and analysis of solder joint reliability for BGA assembly under flexural loading
    The solder joint reliability for BGA (Ball Grid Array) assembly is becoming a more concerned issue as these packages are featuring higher density interconnections, multiple functionality and higher speed combined with smaller size. The traditional test methods for second level PCBA (Printed Circuit Board Assembly) mechanical reliability monitor the electric resistance changes of Daisy chains in the test samples under 4-point bending. The method has been documented by Interconnecting and Packaging Electronic Circuits and Joint Electronic Devices Engineering Council in PC/JEDEC 9702 standard. The effectiveness of the test has been questioned when applied to the new lead-free soldered packages. Due to the failure mode shift from solder joinicopper pad interface cracking in Tin-lead PCBAs to pad-cratering cracking in leadfree packages, the electrical continuity monitoring becomes ineffective in detecting the interconneCt failure. On the other hand, the strain gauges recorded PCB strains during bend tests show little increase that would be indicative of an onset failure. This project applies Fiber Bragg Grating (FBG) strain sensors to detect the pad-cratering failure. FBO have been employed widely in different areas of engineering due to its advantages of small size, light weight and high sensitivity. In this project the FBG sensors are laid to the vicinity of the BGA substrate comers. By detecting and recording the solder joint fracture induced strain release, the onset of pad-cratering is explicitly revealed. The study has demonstrated that the FBG sensors are much more sensitive than electric resistance strain gauges in detecting the substrate strain release in BGA assembly 4-point bend testing due primarily to the sensor's much smaller geometric size. By placing the sensors very close to the comer solder joints, the new test obtains accurate strain information related to the first solder joint cracking. Furthermore, the recorded strain release enables the detecting, understanding and analysis of the critical load of the solder joint fracture, the brittle and ductile fractures and related strain relaxation phenomenon during the PBGA flexural loading, etc.
    Testing recycled concrete aggregate suffering different levels of alkali-silica reaction for use in new structures
    Testing recycled concrete aggregate suffering different levels of alkali-silica reaction for use in new structures
    As concrete reaches the end of its service life, it is demolished and placed in landfills, which is not sustainable as this consumes land space. Many demolished structures are crushed into recycled concrete aggregate (RCA) and used in new construction work to reduce concrete waste. To be used in concrete, the effects of RCA on the new structures should be carefully examined. The RCA studied in this research is an alkali-silica reactive gravel from Sudbury, Ontario. The RCA was obtained from different elements of a 20-year old bridge that suffered different levels of deterioration. It was determined that the level of deterioration that affected the previous structure does not significantly affect the expansion that will occur in the new structure. It was also determined that the expansion could be mitigated through the use of supplementary cementing materials although higher levels are required compared those required for the virgin aggregate.
    Tetraspanins Associated With oxLDL and IgG Mediated Phagocytosis In Human U937 Macrophages
    Tetraspanins Associated With oxLDL and IgG Mediated Phagocytosis In Human U937 Macrophages
    One of the crucial key targets in treatment of diseases are cell surface proteins, such as receptor complexes, and their associated signaling pathways. The Fc receptor is one of the most important phagocytic receptors of the cells of immune system. The ligand of the Fc gamma receptor is immunoglobulin G (IgG), which triggers the engulfment of foreign molecules coated by antibodies by a process called phagocytosis. A Specialized subset of cells including macrophages engulfs foreign particles by the Fc receptor. Another phagocytic receptor of macrophages is the CD36 receptor, which binds the ligand oxLDL and is known to be involved in the development of atherosclerotic lesions in the arteries. A few members of the Tetraspanin proteins have been found to be associated with theses receptors in macrophages. Tetraspanins may act as “molecular facilitators” grouping specific cell-surface proteins and thus increasing the formation and stability of functional signaling complexes. There is a significant amount of research done on the receptors of the surface of macrophages, however, the proteins associated with these receptors, their potential signaling pathways and the mechanisms involved are not yet fully understood. This thesis aims to investigate the presence and potential functional role of the specific Tetraspanin isoforms in Fc and CD36 mediated phagocytosis. Silencing RNA, quantitative assays of phagocytosis, and laser scanning confocal microscopy were used to test the phagocytic efficiency of macrophages in IgG and oxLDL mediated phagocytosis. Understanding the regulatory roles of Tetraspanins can provide insight into various immune diseases.
    Texture classification using gene expression programming
    Texture classification using gene expression programming
    In computer vision, segmentation refers to the process of subdividing a digital image into constituent regions with homogeneity in some image characteristics. Image segmentation is considered as a pre-processing step for object recognition. The problem of segmentation, being one of the most difficult tasks in image processing, gets more complicated in the presence of random textures in the image. This paper focuses on texture classification, which is defined as supervised texture segmentation with prior knowledge of textures in the image. We investigate a classification method using Gene Expression Programming (GEP). It is shown that GEP is capable of evolving accurate classifiers using simple arithmetic operations and direct pixel values without employing complicated feature extraction algorithms. It is also shown that the accuracy of classification is related to the fact that GEP can detect the regularities of texture patterns. As part of this project, we implemented a Photoshop plug-in that uses the evolved classifiers to identify and select target textures in digital images.
    The "Other" Mexicans: Transnational Citizenship And Mexican Middle Class Migration In Toronto, Canada
    The "Other" Mexicans: Transnational Citizenship And Mexican Middle Class Migration In Toronto, Canada
    Mexico has one of the highest numbers of emigrants in the world (Martin, 2009) and Canada is one of the states with the highest per capita immigration rates globally (Léonard, 2011). Mexico and Canada are typical examples of immigrant and emigrant countries and both countries have developed policies and strategies that aim to foster civic participation among their immigrant and emigrant population respectively (Martin, 2009; Goldring, 2002; Barry, 2002; Li, 2002; Reitz, 2005; Bauder, 2011). In Canada, academic research on immigration has centred on the effect immigration policies and practices have on including and excluding immigrants from exercising citizenship rights but it has tended to ignore the effect emigration policies have in the development of transnational citizenship practices, such as civic engagement, political participation, social activism, and acts of solidarity that transcend the frontiers of the nation-state. This has left important questions unanswered on how transnational citizenship is developed and exercised in a migration context including: 1) which policies and practices immigrants use to exercise transnational citizenship; 2) what is the impact of transnational citizenship practices in terms of the expansion and contraction of citizenship rights in the context of migration; 3) who is included and excluded by emigration policies promoting transnational citizen engagement; and 4) how do internal community issues, conflicts, cooperation, and solidarity affect the process of transnational enacting of citizenship? I attempt to fill this research gap by studying the effects Mexican emigration policies have on promoting transnational citizenship practices among middle class Mexican immigrants in Toronto and other cities in Ontario and by showing the avenues these immigrants use in order to participate civically with Mexico and with the Mexican diaspora in Canada.
    The "good" mother:  experiences of Canadian adolescent mothers living in rural communities.
    The "good" mother: experiences of Canadian adolescent mothers living in rural communities.
    Adolescent mothers and their children are at risk for suboptimal health outcomes making adolescent motherhood a public health concern. However, the experiences of rural-living adolescent mothers are not well understood. Using Lieblich, Tuval-Mahiach, and Zilber's (1998) narrative methodology approach, the experiential accounts of three rural-living adolescent mothers was explored. Reflecting Goffman's (1959) presentation of self, the findings of this study revealed how adolescent mothers attempted to construct and present their notion of being a good mother, while coping with complicating rural factors. The need to present as a good mother, the lack of anonymity associated with rural living, and geographical barriers had particular implications for the way in which adolescent mothers access and use professional and personal supports. Maintaining relationships with the infants' fathers, even when that relationship exhibited unhealthy characteristics, was important for study participants. Implications for practice, education, and recommendations for future research are discussed.