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Integrated and Heterogenous Mobile Edge Caching (MEC) Networks
Get PDFThe recent phenomenal growth of the global mobile data traffic, mainly caused by intelligent Internet of Things (IoTs), is the most significant challenge of wireless networks within the foreseeable future. In this context, Mobile Edge Caching (MEC) has been recognized as a promising solution to maintain low latency communication. This, in turn, improves the Quality of Service (QoS) by storing the most popular multimedia content close to the end-users. Despite extensive progress in MEC networks, however, there are still limitations that should be addressed. Through this Ph.D. thesis, first, we perform a literature review on recent works on MEC networks to identify challenges and potential opportunities for improvement. Then, by highlighting potential drawbacks of the reviewed works, we aim to not only enhance the cache-hit-ratio, which is the metric to quantify the users’ QoS, but also to improve the quality of experience of caching nodes. In this regard, we design and implement a Deep Reinforcement Learning (DRL)-based connection scheduling framework [1] to minimize users’ access delay by maintaining a trade-off between the energy consumption of Unmanned Aerial Vehicles (UAVs) and the occurrence of handovers. We also use D2D communication [2] to increase the network’s capacity without adding any infrastructure. Another approach to effectively use the limited storage capacity of caching nodes is to increase the content diversity by employing the coded caching strategies in cluster-centric networks. Despite all the researches on the cluster-centric cellular networks, there is no framework to determine how different segments can be cached to increase the data availability in a UAV-aided cluster-centric cellular network. Moreover, to date, limited research has been performed on UAV-aided cellular networks to provide high QoS for users in both indoor and outdoor environments. Through this thesis research, we aim to address these gaps [3,4]. In addition, another goal of this thesis is to design real-time caching strategies [5–9] to predict the upcoming most popular content to improve the users’ access delay. Last but not least, capitalizing on recent advancements of indoor localization frameworks [10–14], we aim to develop a proactive caching strategy for an integrated indoor/outdoor MEC network
Spectroscopic Analysis and Photostability Assessment of Lanthanide-Doped Upconverting Nanoparticles Sensitized with IR820 Derivatives
Get PDFLanthanide upconverting nanoparticles (LnUCNPs), known for their luminescence when irradiated with near-infrared (NIR) light, often face challenges limited absorption capabilities, particularly due to the low absorption cross-section of sensitizer ions likeYb3+. Incorporating NIR dyes has shown promise in enhancing the upconversion luminescence of LnUCNPs by efficiently
harnessing NIR light and channeling this energy to the sensitizer ions. The higher absorption cross section of these NIR dyes, compared to Yb3+, amplifies the LnUCNPs' absorption prowess.
However, the inherent photoinstability of such organic dyes hinders their practical applications, especially when sustained NIR exposure is essential.
Addressing this challenge, this research work delved into improving the photostability of dye sensitized
LnUCNPs. The focus was on IR820 dye, when functionalized with thiophenol groups bearing para substituents of varied electron density, showcased enhanced stability. This enhanced
stability was evident when IR820-NO2 sensitized NaGdF4:Er3+, Yb3+/NaGdF4: Yb3+ excited at 808 nm manifested brighter upconversion luminescence due to a better overlap with the Yb3+ ion absorption and doubling its photostability duration to 90 minutes. In the process, this research also unearthed certain inconsistencies in the prevalent literature pertaining to the 980 nm and 808 nm wavelengths and the energy back-transfer dynamics from Er3+ to the dye.
Progressing further, the IR820-COOH dye was functionalized with APTMS and was incorporated into a silica framework surrounding NaGdF4:Er3+, Yb3+/NaGdF4: Yb3+. An in-depth analysis underscored the superior photostability and upconversion luminescence of this embedded system when pitted against covalent surface-linked and electrostatic variants. This optimized embedded system was also examined vis-à-vis Nd3+ doped nanoparticles, both being excited at 808 nm. Using the system's enhanced attributes, we adapted it into an 808 nm-responsive Fenton-type catalyst. This adaptation was achieved by coating the system with a wide-pored silica shell that incorporated hematite nanoparticles. This culminated in an efficient degradation of the Rhodamine B pollutant, a significant environmental menace introduced by the textile sector.
To encapsulate, this thesis paves the way for bolstering the photostability and versatility of dye sensitized LnUCNPs, employing intricate dye modifications and embedding strategies, heralding new possibilities for applications
The ecology and evolution of the Methylophilaceae family across aquatic salinity gradients
Get PDFAnthropogenic pressures on aquatic environments are leading to rapid environmental change. One of the main environmental stressors in marine environments is change in salinity. It is a major factor that controls the distribution and diversity of organisms. As microbes are essential to maintaining ecosystem services and biogeochemical cycling, it is important to understand the diversity, distribution, ecology, and metabolism of bacteria living in these rapidly changing environments. In this thesis, bacterial adaptation and evolution is investigated across salinity gradients spatially and temporally. A targeted approach, using the Methylophilaceae as a model family to monitor change, allowed us to explore and increase our understanding of niche differentiation, genome streamlining, and ecological adaptations.
We first studied the diversity and distribution of the Methylophilaceae family across ¬a spatial salinity gradient where we detected the clades from freshwater to brackish-marine waters in the Saint Lawrence Estuary and Bedford Basin. These distinct populations correlated with specific salinity concentrations, which suggests different ecological roles in response to environmental gradients. This led us to also investigate the adaptation and evolution of Methylophilaceae in response to changing environmental conditions over time and space in the increasingly freshening Arctic Ocean. We found evidence for endemic Arctic Ocean taxa as well as a novel clade, BS01, which was adapted to the unique lower salinity surface waters of the Arctic Ocean. We also discovered that over time, the Methylophilaceae family showed an increase in specific taxa associated to the years experiencing the highest amount of freshening.
The work in this thesis has increased our understanding of the Methylophilaceae family and their niche differentiation to distinct environmental conditions. Overall, this work has larger implications for understanding how climate change is affecting northern aquatic ecosystems and how microbes are evolving and adapting to this change
Global sustainability discourses and local framing processes: A case study of the Evolution of a Smart Energy System Frame in the U.K. Electricity Industry
No full textI investigate the case of the emergence and evolution of the smart energy systems frame in the UK electricity industry from 2008 to 2017 to understand how the meanings associated with sustainability-driven technologies are defined, interpreted, evolved, and may change the field frame. Furthermore, how the hegemonization of powerful actors unfolds in the process of technological and institutional meaning-making and slows down the process of radical institutional change. Theoretically, I draw on the institutional theory, emphasizing the process of the social construction of meaning (Berger & Luckmann, 1966; Zilber, 2008) within organizational fields, framing literature (Benford &Snow, 2000), and neo-Gramscian theory of hegemony (Levy & Egan, 2003).
Based on a longitudinal qualitative study, I elaborate on three main processes (Elite theorization, Industry translation and experimentation, and Deliberation) through which various actors shape, experiment with, and challenge new collective technological frames to form a new field frame. I also elaborate on two processes of hegemonization and pluralization that counteract each other in the process of institutional change. Particularly, I contribute to the hegemony and institutional change theory by introducing concepts of Inter-institutional versus intra-institutional hegemonization and Inter-institutional versus intra-institutional pluralization. Inter-institutional hegemonization refers to the use of material and discursive elements by central actors and fossil-fuel energy providers to maintain the current field-level institutional system, secure non-renewable energy sources such as nuclear energy and gas in the industry value chain, and justify the continuation of investment in traditional technologies. In this way, they slow down or deviate the transition from the current field frame to the new field frame of smart and low-carbon energy systems. On the other hand, intra-institutional hegemonization refers to constructing the hegemony within the new field frame of the low-carbon smart and flexible energy system. In this kind of hegemonization, energy companies and central and powerful actors explicitly support sustainability transition and invest in renewable and smart technologies but draw on various discourses and mechanisms to marginalize other pathways of decarbonization and reinforce the centralized and large-scale energy system where they can maintain their market hegemony
Beyond the First Touchpoint: How Initial Engagement, Marketing Communication, and Store Proximity Shape Multichannel Purchasing
Get PDFIn the evolving retail landscape, companies embrace multichannel retailing to address consumer needs. Central to this discussion is the initial purchasing channel’s impact on multichannel engagements, which is complexified by the influential role of marketing communication methods (i.e., mail and email) and store proximity. This study focuses on a multinational consumer packaged goods company operating online and physical stores in Quebec, Canada. It explores two research questions: (1) how does a consumer's initial offline engagement impact total purchases in different channels? (2) how do communication methods and store proximity impact the relationship between the initial offline engagement and total purchases in different channels? The study focuses on the total quantity of products purchased for a specific category in online and offline channels. First, the findings suggest how consumers who first engage offline tend to make 92.88% fewer online purchases and 948.56% more offline purchases than consumers who first engage online. Second, for consumers who first engage offline, being on the direct mailing list may mitigate the decline in online purchases while potentially mitigating the increase in offline purchases. Third, for consumers who first engage offline, being on the email list may mitigate the decline in online purchases while potentially mitigating the increase in offline purchases. Fourth, for consumers who first engage offline, store proximity may amplify the decline in online purchases while potentially amplifying the increase in offline purchases. This study contributes to the existing knowledge of multichannel purchasing behavior, offering insights for retailers navigating the world of multichannel retailing
A Privacy-Preserving Edge Computing Solution for Real-Time Passenger Counting at Bus Stops using Overhead Fisheye Camera
Get PDFSuccessful transit planning in smart cities requires automated and efficient passenger counts at bus stops while also respecting the privacy of passengers—a paramount consideration in the age of responsible AI. In this thesis, we describe the implementation and development of a real-time passenger counting system at bus stops on Nvidia Edge devices powered only by solar panels with limited memory while not compromising privacy or incurring substantial costs. Numerous studies have developed and applied computer vision people detection techniques, although this has not been applied and optimized explicitly to edge-computing passenger counting at bus stops. In this regard, we evaluated different object detection models using a novel dataset from an overhead fisheye lens camera of passengers at a bus stop that we developed to analyze and improve the accuracy of the passenger counting system. We also optimize and reduce the models to allow them to be deployed on edge devices. We find that YOLO-V4 with mAP of 87% outperforms DetectNet-V2 and Faster-RCNN. The best object detection model has then been optimized and deployed on the Nvidia Jetson device, and the performance and efficiency of the passenger counting system have been evaluated. Deployment via Nvidia DeepStream on the edge showcased a more than 50% reduction in GPU, CPU, and memory consumption, enhancing efficiency while conserving energy. As a result, we present a more accurate and efficient edge-computing video analytics solution for an ethically responsible passenger counting system at the smart city bus stop
UTILIZING AGRICULTURAL WASTES TO PRODUCE BIO-GREEN CONCRETE AND ZERO-CEMENT PARTICLE BOARDS
Get PDFA growing number of building projects seek eco-friendly and sustainable materials to reduce their environmental impact. Incorporating agro-waste into concrete production is one promising strategy. Agro-waste often considered a replacement of coarse and fine aggregate or fiber, is a rich source of renewable and biodegradable materials that can enhance the performance and reduce the environmental footprint of these construction components. In previous studies, rice husk, coconut coir, sugarcane bagasse, and a variety of agricultural residue materials were found to be suitable for incorporation into concrete. The availability and affordability of these materials make them attractive alternatives to traditional non-renewable resources. Moreover, it highlights the importance of using agro-waste for environmental reasons, such as reducing the carbon footprint of construction materials and reducing the need for landfill disposal. These practices align with the principles of a circular economy, promoting the responsible use of resources. A discussion is provided of the performance and properties of the materials produced, including their strength, durability, and insulation capabilities. Agro-waste can enhance these attributes and increase the applications of concrete tiles and particle boards, contributing to the creation of sustainable and energy-efficient buildings. Agro-waste can be utilized to manufacture concrete tiles and particle boards in an environmentally friendly manner. The purpose of this study is to provide a summary of the potential benefits of integrating agro-waste into sustainable practices while addressing the challenges and opportunities associated with this innovative approach. This paper presents findings that are intended to inspire further research and development in the field of green construction materials
Model-free Control of Soft Robots for Intraluminal Surgical Intervention
No full textSoft robots have significantly impacted the field of minimally invasive surgeries, owing to their flexibility, adaptability, and capability to maneuver through previously inaccessible, deep-seated regions. In the realms of lung and ENT, robot-assisted endoluminal interventions have yielded promising initial results, particularly in cancer detection and treatment. These advancements offer new possibilities for early diagnosis and effective therapeutic interventions in oncology.
A persistent challenge lies in the precise navigation of these flexible instruments towards specific anatomical targets and in maintaining a consistent aiming direction while inserting biopsy or interventional tools through the lumens. These tasks are further complicated by intrinsic physiological movements, such as breathing and heartbeats.
The objective of this study is to explore the feasibility of adapting appropriate modeling and control approaches for soft robots in endoluminal lung and ENT interventions. Soft robots necessitate a control system capable of accurately understanding their intricate behavior, thereby ensuring precision in operation. The initial phase of this research introduces a groundbreaking mechanistic model for soft robots, incorporating hyperelastic effects and stiffness adaptation. The focus here is on experimental investigations into tip position control for soft robots.
The second phase of the research details the development of an innovative, model-free optical flow-based control method, significantly enhancing precision in tendon-driven soft robotic surgery for intraluminal procedures. The integration of a micro-camera within the robot's tip, providing continuous visual feedback, is a key advancement of this system. These results hold great promise for elevating operational precision in robotic-assisted surgery and enhancing intraluminal navigation.
The core challenge addressed by this research is the development of a real-time control system that facilitates precise robotic manipulation during surgeries while being user-friendly for surgeons
Data-Driven Approach for Personalization of Electropolishing Operations in Used Baths
Get PDFIndustrial electropolishing facilities can enhance their competitiveness in the market by embracing the concept of mass personalization, which involves closely integrating customers in the design process to accommodate their specific preferences. Traditional electropolishing operations rely heavily on skilled operators and costly trial-and-error experiments to determine the suitable process parameters for obtaining their target surface quality. The ongoing deterioration of the polishing bath further complicates achieving personalized outcomes. To adopt the mass personalization trend, electropolishing operations need to implement approaches that ensure consistent polishing results while enabling the rapid identification of optimal process parameters for achieving personalized surface finishes.
The goal of this work is to develop a prediction tool to determine the suitable polishing parameters in a deteriorating polishing bath to attain the target surface quality. The study uses surface roughness and brightness measurements, as well as SEM images of the parts to investigate the effect of bath conditions on the final surface finish of electropolished parts. Multiple explanations are suggested to justify the compromised performance of heavily-used baths. The study also proposes a current-voltage plot that can be used as a tool to determine the polishing voltages associated with the emergence of some surface defects under varying bath conditions.
A substantial dataset is next compiled from electropolishing experiments conducted under different bath states and using various polishing parameters. This dataset is later subjected to several machine learning algorithms to determine the model that best represents the data. The Random Forests model is selected as the foundation for the target prediction tool, which demonstrates excellent performance on both the dataset and previously unseen scenarios. The constructed tools offer a comprehensive perspective on electropolishing outcomes across different bath and part conditions and polishing process parameters.
Moreover, by facilitating the attainment of the desired surface finish even in heavily-utilized electrolytes, the developed tools diminish the need for frequent electrolyte replenishment and the expensive disposal of hazardous waste, thereby benefiting the environmen
On Her Lips, From God: Sexual Violence, Charismatic Speech, and Authority in Early Christianity
Get PDFThis dissertation is a feminist historical literary analysis of select early Christian narratives in which epistemology and charismatic speech are linked to sexual violence: the Hypostasis of the Archons (HypArch), the Acts of Paul and Thecla (ATh), and the Acts of the Apostles (Acts). I read these narratives in broader debates within early Christ communities about whose charismatic speech could obtain divine status. I argue that sexual violability and assault figures into the texts’ representations of authority. Moreover, these sources rely on dominant ancient understandings of sexuality that normalized the sexual violability of marginal groups, including women, ethnic others, and enslaved persons.
The introductory chapter outlines my methodology, the context of speech and authority in early Christ assemblies, and dominant conceptions of sexuality and gender related to sexual violence. Chapter one addresses Eve’s rape in HypArch and shows how this sexual violence undermines her prophetic role and place in the text’s soteriological vision. In chapter two, I examine the narratives of Norea (HypArch), Eve’s daughter, and Thecla (ATh), and demonstrate that, though early Christian sources assume the normativity of sexual violence, they also imagine moments in which characters (in this case, high-standing women) could resists such violence. The final two chapters consider sexual violence, charismatic speech, and authority in the representation of three enslaved persons in Acts, the Ethiopian eunuch (Acts 8), the prophetic enslaved girl (Acts 16), and Rhoda (Acts 12). Reading these scenes in the context of the sexually violent nature of ancient slavery, I show how Luke’s rhetoric relies on the inherent sexualization of enslaved persons to bolster the image of the Way and the apostles while undermining the authoritative potential of these characters.
This dissertation reveals how some early Christian configurations of knowledge and charismatic power were tied to sexual status and often left the normalization of sexual violence unexamined. In making this assertion, I link understandings of sexual violence past and present that follow from the #MeTooMVMT, such as, how current victim/survivors are held in suspicion and how institutions and academic subfields, including early Christian studies, have been complicit in enabling a culture of predation