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Performance Modeling of Vehicular Clouds Under Different Service Strategies
Get PDFThe amount of data being generated at the edge of the Internet is rapidly rising as a result of the Internet of Things (IoT). Vehicles themselves are contributing enormously to data generation with their advanced sensor systems. This data contains contextual information; it's temporal and needs to be processed in real-time to be of any value. Transferring this data to the cloud is not feasible due to high cost and latency. This has led to the introduction of edge computing for processing of data close to the source. However, edge servers may not have the computing capacity to process all the data. Future vehicles will have significant computing power, which may be underutilized, and they may have a stake in the processing of the data. This led to the introduction of a new computing paradigm called vehicular cloud (VC), which consists of interconnected vehicles that can share resources and communicate with each other. The VCs may process the data by themselves or in cooperation with edge servers.
Performance modeling of VCs is important, as it will help to determine whether it can provide adequate service to users. It will enable determining appropriate service strategies and the type of jobs that may be served by the VC such that Quality of service (QoS) requirements are met. Job completion time and throughput of VCs are important performance metrics. However, performance modeling of VCs is difficult because of the volatility of resources. As vehicles join and leave the VC, available resources vary in time. Performance evaluation results in the literature are lacking, and available results mostly pertain to stationary VCs formed from parked vehicles. This thesis proposes novel stochastic models for the performance evaluation of vehicular cloud systems that take into account resource volatility, composition of jobs from multiple tasks that can execute concurrently under different service strategies. First, we developed a stochastic model to analyze the job completion time in a VC system deployed on a highway with service interruption. Next, we developed a model to analyze the job completion time in a VC system with a service interruption avoidance strategy. This strategy aims to prevent disruptions in task service by only assigning tasks to vehicles that can complete the tasks’ execution before they leave the VC. In addition to analyzing job completion time, we evaluated the computing capacity of VC systems with a service interruption avoidance strategy, determining the number of jobs a VC system can complete during its lifetime. Finally, we studied the computing capacity of a robotaxi fleet, analyzing the average number of tasks that a robotaxi fleet can serve to completion during a cycle. By developing these models, conducting various analyses, and comparing the numerical results of the analyses to extensive Monte Carlo simulation results, we gained insights into job completion time, computing capacity, and overall performance of VC systems deployed in different contexts
The Right for Aging: Investigating the Interrelations between Negative Aging Stereotypes, Perception of Aging, Older Adults’ Cognitive Performance and Impacts of Cognitive and Exercise Interventions
Get PDFWhile research on patterns of cognitive decrements in later life has focused on biological processes, psychosocial processes, such as negative aging stereotypes (NAS), an individual’s learned beliefs about the characteristics or attributes of older adults as a group, and self-perception of aging (SPA), the cognitive evaluation of oneself relative to aging, have also been associated with poorer cognitive performance, decreased well-being, and disengagement from healthy behaviours. For example, it is suggested that NAS is negatively related to verbal memory performance in older adults, although little is known about its potential relationship with other cognitive domains. Furthermore, usual methodologies do not align with clinical procedures, creating a gap between research and clinical settings. Additionally, the literature supports satisfaction with aging as a central aspect of subjective well-being in older age but remains understudied despite evidence of internalized ageism among older adults. Importantly, evidence concerning ways to improve NAS and SPA in older adults is lacking. This is problematic, given that psychological processes may be particularly amenable to interventions.
The first manuscript of this thesis explores the relationship between NAS and SPA, and older adults’ cognitive performance. More specifically, we measured explicit and implicit NAS and SPA in older adults. We assessed their verbal and visuospatial memory, working memory and processing speed using a clinical framework. Results showed that higher explicit NAS negatively correlated with verbal and visuospatial memory and processing speed. Explicit NAS predicted processing speed and visuospatial memory, while implicit NAS predicted verbal memory.
The second manuscript investigated the effect of aerobic, gross motor abilities, or cognitive training on changing NAS and SPA. Results suggested that a 3-month regimen of either training type led to improvements in SPA independently of better fitness and cognition. On the other hand, NAS remained stable.
Despite best clinical practice, older adults come into the assessment room with beliefs that may adversely related with their cognitive performance beyond verbal memory. However, SPA can be improved through various types of training, which could reach a broader range of older adults with multiple interests and initial abilities
Being-with GalleryGardi: A meshwork learning in galleries and museums
Get PDFThis study investigates a transnational walking art practice known as GalleryGardi applied in local engagements, an event of being-with entanglements of body-object-space in meshwork connections. This inquiry is focused on how embodied knowledge forms within this pedagogical event that takes place in the context of galleries and museums. Through embodied experimentation, a corresponding relation is formed among body-object-space as an event of being-with, opening a creative space to embrace the unknown, the unpredictable, and the might-be-possible—both ontologically and epistemologically—in our dynamic socio-material encounters. The meshwork thinking in this study allows for the entanglement of theory-methodology-practice in a way that no single thread of the study is given precedence over another; threads (textual and visual) are knotted together to create a comprehensive expression referred to as GalleryGardi, constituting an event of being-with. Adopting meshwork thinking, the methodological movements of this study intersect with an arts-based research approach to community-based participatory practice, informed by walking and visual ethnographies. This dissertation addresses the significance of affective moments in walking, embodied experiences, co-conservations, being a community, vernacularity, and attentionally of body-object-space correspondence through a co-creative doing-making-meaning.
Inspired by eight weeks of walking in Montreal's art museums and galleries, this thesis is structured as a series of threads of inquiry, each of which serves as movements of our walks, encounters, and moments of exploration and intuition. This inquiry reveals GalleryGardi’s potential to be adopted as a transnational art practice and of its capacity for being-with those who collaborate and correspond, in which ethics of care are activated, not only for ourselves, but for others in proximity. Such practice allows us to attune to the relationality of our bodies with artworks and space of galleries and museums toward a human-non-human entanglement. The transnational movement of this artful practice from its origin in Tehran, Iran to Montreal’s art scenes opens possibilities for investigating the pedagogical and educational capacities of the public space of museums and galleries in an alternate way, grounded in trans- practices: that is, respectful of diversity in language, race, gender, and ethnic backgrounds
Design of a Spoke Type PMSM with SMC Stator Core for Traction Applications
Get PDFThe requirement of a clean energy environment has created the need for electric vehicles in the automotive industry. Electrical machines are the most vital component in traction applications as they provide electromechanical energy conversions. Traction applications require motor drive systems that can operate with high torque and high-power densities with reduced maintenance costs and losses. Since the 20th century, induction machines (IMs) have been a popular choice owing to ruggedness and reduced cost (absence of commutators and slip rings). But it is less efficient when compared to the other kinds of AC machines such as the permanent magnet synchronous machines (PMSM). In the IM, a part of the rotor flux is created by the currents flowing in the rotor conductors, made up of either aluminium or copper bars. But in PMSMs, the rotor flux is created by the permanent magnets (PMs) mounted on the rotor structure. The absence of the rotor cage reduces the mass of the PMSMs, resulting in lower inertia and faster torque response when compared to IMs. Also, the lack of rotor currents eliminates the rotor losses leading to higher efficiency.
In PMSM machines, a realistic value of the copper fill factor ranges between 35% to 40% with the laminated stator for air cooling. A higher current rating is required for a low voltage machine to meet the torque and power specifications. Higher current rating machines usually utilize parallel windings to reduce the number of strands. With the parallel winding pattern, the turns per coil will be multiplied with the number of parallel paths reducing the wire diameter and increasing the copper fill factor. The high copper fill factor increases the contact between the wires, and this allows for better heat transfer from the conductors. Therefore, the temperature of the windings is reduced, the resistance decreases and also the copper losses.
This thesis compares the performance of the SMC and laminated steel-based design for a radial flux outer rotor permanent magnet synchronous machine (PMSM) and its impact on the core loss at higher frequencies. Also, this thesis examines two different winding patterns (distributed and fractional) for field weakening operation with a surface mount outer rotor PMSM.
This thesis presents a cold spray additive manufacturing technique to spray the NdFeB magnet on to the rotor laminations. With this technique, magnet shaping is more feasible. The magnets are sprayed in a cobra shape to obtain better electromagnetic performances. This cold spray technique is developed at NRC Canada which makes the magnet shaping inexpensive.
This thesis presents a modified spoke type rotor that significantly reduces the torque ripple, back electromagnetic force (EMF) harmonics, and cogging torque from conventional spoke type designs. The effectiveness of the modified spoke type rotor is proved with state-of-the-art designs such as Toyota Prius and Honda Accord motors. Three different SMC materials are compared for the same machine specification. The tooth body length of SMC stator is varied from 36 mm to 56 mm to analyze the performance of the motor.
Along with the modified spoke type rotor focus is on a segmented soft magnetic composite (SMC) stator core to improve the copper fill factor and improve torque density by reducing the tooth length to allow additional space for the end windings within the stack length of the motor. A comparison between the laminated steel stator and SMC stator is presented. The laminated motor is capable of producing higher torque than the SMC motor when both machines are designed to operate with the same temperature, though the torque density in terms of volume of SMC motor is higher than the laminated motor. In all cases, the machines are designed to fit into the same frame. A cost comparison is presented between the SMC and laminated motors, which shows that SMC motors can be manufactured at lower cost than laminated motors. Also, the SMC stator includes axial magnet segmentation, flux weakening capability, thermal analysis, stator stress analysis due to electromagnetic forces, and a rotor mechanical stress analysis.
Finally, this thesis aims to present the development of SMC teeth considering manufacturing and assembling challenges. It briefly presents the SMC tooth manufacturing including the heat treatment. Also, it presents the rotor manufacturing with prototype pictures. Finally, it presents the experimental results for the SMC motor, along with the simulation results
Three Essays on the Governance of Cybersecurity
Get PDFThis dissertation consists of three interrelated essays that examine the governance of cybersecurity. The first essay synthesizes the literature on the of cybersecurity risks and incidents to identify its drivers, informativeness, quality, theoretical perspectives, and future directions. The review identifies several drivers for cybersecurity disclosure, highlights that while the level of informativeness of such disclosure meets the usefulness expectations of regulators, its quality falls short, mostly lacks an explicit theoretical framework, and uses predominantly textual content analysis and event studies. The review identifies the need for research in both governance and management of cybersecurity disclosure, thus providing the motivation for the second and third essays. The second essay examines where cybersecurity risk oversight resides within a firm’s governance structure, what determines such positioning, and how it impacts the firm’s response to a cybersecurity breach. In proxy statements, breached firms explicitly disclose oversight assignment with a wide variation, ranging from full board to a named board committee - the audit committee being the most common. Results show that board connectedness and cyber competency are positively associated with oversight assignment, full board oversight is more likely with smaller boards, and boards’ shareholding and cyber competency steer oversight to the audit committee. In the event of a breach, the presence of oversight decreases the time firms take to announce and resolve the breach, as well as reduces the recurrence of breaches. While the audit committee cybersecurity oversight discloses and resolves the breach quicker, full board oversight leads to fewer recurrences. The increase of data breaches leads firms to adopt various risk management strategies, hence the third essay examines the relation between cyber insurance disclosure and a firm’s likelihood of being target of a future breach. Using textual analysis of the risk factors disclosed in 10-K filings and comparing cyber insurance disclosures of firms that are breached to those that are not, the evidence shows that firms disclosing cyber insurance have a significantly higher subsequent probability of being breached. Furthermore, it appears that disclosing cyber insurance leads to delayed public breach disclosure but more timely breach resolution, and higher breach recurrence
White Matter Microstructural Correlates of Cognitive and Motor Functioning Revealed via Multimodal Multivariate Analysis
Get PDFRecent advances in cognitive neuroscience emphasise the importance of healthy white matter (WM) in optimal behavioural functioning. It is now widely accepted that brain connectivity via WM contributes to the emergence of behaviour. However, the association between the microstructure of these fibre and behaviour is poorly understood. This is due to indirect and overlapping methods of assessing microstructure, and the oversimplification approaches in assessing behaviour. Here, we used the Mahalanobis Distance (D2) to integrate 10 metrics of WM derived from multimodal neuroimaging that have strong ties to microstructure. The D2 was chosen because it measures the voxelwise distance between every subject and the average, while also accounting for the overlap between the metrics. To examine WM-behaviour associations, we used multivariate regression to examine the voxelwise correlates of 2 cognitive and 2 motor tasks, which allowed us to compare within and across domains in white matter. We observed that behaviour is organised in cognitive, motor, and integrative variables that are widespread in their associations with WM, from frontal to parietal regions. Our results highlight the complex nature of microstructure and behaviour, and show the need for multivariate modelling when examining brain-behaviour associations
Numerical modeling of settlement and deformation behavior of wooden pile reinforced railway embankments on peat foundation soils
Get PDFA number of rail embankments in Canada are constructed on land surfaces covered by organic soils such as peat. Peat soils are known to exhibit enormous deformation potential owing to their excessive water content with low strength. Because of this, railway embankments built on peat experience reoccurring problems of settlement and deformation. Consequently, this increases the cost of maintenance and impedes the safety and stability of a slope under moving freight train conditions. Thus, to stabilize the peat under the railway embankment, this research modeled the behavior and evaluated the effectiveness of driven wooden piles as a method of stabilization. Employing the finite element shear strength reduction (FE-SSR) method, the development of excess pore water pressure and settlement of 2-dimensional models are investigated thoroughly. Using the Biot’s consolidation theory, a coupled model providing an in-depth understanding of the mechanism of development of excess pore water pressure and stress essential for understanding the development of settlements is considered. Key factors such as geometric characteristics of the slope, wooden piles (length, diameter, and spacing), and freight train speeds were conducted through a series of parametric studies to ascertain their effects on embankment failure. A sensitivity analysis was introduced to individually investigate each parameter of the wooden piles and its effect on slope stability. Adopting a minimum factor of safety of 1.3, slopes with different geometric parameters and wooden piles, and maximum safe train speed is required to ensure the adequate performance of slopes considering the high compressibility nature of peat. The results illustrate that a slope with 2H:1V slope inclination exhibits a larger degree of settlement and deformation and a considerable increase in pore water pressure under a high-speed train load. Details of the maximum allowable speed a train can use, given the geometric parameters of the slope, railway embankment height, and wooden piles are finally presented in this study for safe freight train performance
Framing the Farmer’s Protests: An Analysis of Newslaundry and RepublicTV’s Coverage
Get PDFIn late November 2020, tens of thousands of farmers marched to New Delhi, the capital of India, to oppose planned new agricultural regulations introduced hastily by Narendra Modi’s BJP government in June 2020. Up to 250 million people throughout the subcontinent engaged in a 24-hour general strike in support of the farmers of India and their cause. This movement has received international attention and prompted the government to meet the protesters in December 2020, a first in Prime Minister Modi's six-year rule. Throughout the coverage of these protests, news media in India have been heavily divided. This research focuses on an analysis of the news frames mobilized in online coverage by independent news outlet Newslaundry and RepublicTV, one of India’s most popular English-language news outlets. Using a frame analysis, this research concludes that the two news organizations greatly varied in their approaches to covering the protests. RepublicTV branded the farmers as ‘uncooperative’ and the leaders of the farmers’ union as ‘willing to do whatever it takes’ to have the laws repealed. They were called ‘anti-nationals’ who brought ‘shame’ to the nation and the ideals of democracy. Newslaundry, on the other hand, highlighted the voices of the farmers and their plight during the protests and focused on fact-checking other outlets’ coverage while emphasizing the importance of press freedom in India at such a polarizing time. This thesis also goes into detail about the current state of media in India and the rise of biased journalism in the industry
Exploring the influence of socio-demographic factors on fertility decisions among women in Canada
Get PDFThe global decline in fertility rates has drawn the attention of economists, researchers, and policymakers in recent decades. Given the economic and social implications of population changes, it is important to analyze what underlying factors have influenced fertility decisions over time, and what is behind the sharp change in the decision-making process regarding family size, and hence, population growth. The present paper analyzes the influence of different socio-demographic factors on two main fertility decisions: the number of children and the age of women at first child. The analysis is done employing data from the Canadian Social Survey for the years 2006, 2011, and 2017, proposing an estimation with an ordered logit model framework and accounting for possible cohort effects by incorporating birth-control variables. Main findings suggest that higher levels of education, urbanity, certain regions, and being religiously unaffiliated are associated with a higher likelihood of reporting fewer amount of children. These results also contribute to reporting a first child at an older age, except for the variable that captures religious attendance, which is associated with a higher likelihood of reporting a first child at an older age despite the fact that attending religious events is linked to a higher amount of children
Broadcasting in highly connected graphs
Get PDFThroughout history, spreading information has been an important task. With computer networks expanding, fast and reliable dissemination of messages became a problem of interest for computer scientists. Broadcasting is one category of information dissemination that transmits a message from a single originator to all members of the network. In the past five decades the problem has been studied by many researchers and all have come to demonstrate that despite its easy definition, the problem of broadcasting does not have trivial properties and symmetries. For general graphs, and even for some very restricted classes of graphs, the question of finding the broadcast time and scheme remains NP-hard. This work uses graph theoretical concepts to explore mathematical bounds on how fast information can be broadcast in a network. The connectivity of a graph is a measure to assess how separable the graph is, or in other words how many machines in a network will have to fail to disrupt communication between all machines in the network.
We initiate the study of finding upper bounds on broadcast time b(G) in highly connected graphs. In particular, we give upper bounds on b(G) for k-connected graphs and graphs with a large minimum degree.
We explore 2-connected (biconnected) graphs and broadcasting in them. Using Whitney's open ear decomposition in an inductive proof we propose broadcast schemes that achieve an upper bound of ceil(n/2) for classical broadcasting as well as similar bounds for multiple originators. Exploring further, we use a matching-based approach to prove an upper bound of ceil(log(k)) + ceil(n/k) - 1 for all k-connected graphs. For many infinite families of graphs, these bounds are tight.
Discussion of broadcasting in highly connected graphs leads to an exploration of dependence between the minimum degree in the graph and the broadcast time of the latter. By using similar techniques and arguments we show that if all vertices of the graph are neighboring linear numbers of vertices, then information dissemination in the graph can be achieved in ceil(log(n)) + C time.
To the best of our knowledge, the bounds presented in our work are a novelty. Methods and questions proposed in this thesis open new pathways for research in broadcasting