21793 research outputs found
Sort by
Camel Imagery in Pre-Islamic Wadi-Rum Rock Art: Translating Social Identity Through Material Traces
Get PDFMy research employs ancient literary sources to help investigate carved she-camel imagery appearing on thirty-three rock faces located within the Jordanian desert of Wadi-Rum. Using excerpts from pre-Islamic poetry as an historical source, this thesis focuses on ancient north Arabian beliefs and practices that were shaped by the she-camel's symbolic and physical presence. The thesis draws on key lines drawn from the ancient rahil-journey, the Maysir, and the Baliyah. The first section introduces how the she-camel may have helped shape ancient Arabian perceptions of individuality. The second section draws on the desert journey of the prominent pre-Islamic poet, Labid, to investigate the spiritual nature and structure of his poem The Mu'allaqah of Labid. Exploring the she-camel as an ancient Arabian metaphor, the third section addresses the animal as a medium connecting the known and "unknown" realms within ancient north Arabian folkloric narratives. Referencing Mieke Bal's inter-disciplinary approach and guided by Erwin Panofsky's iconographic framework, this thesis suggests that she-camel carvings contributed in some way to the conceptualization and materialization of aspects of the north Arabian perception of the self as evidenced, in part, by the ubiquitous and extraordinary visual traces left behind in Wadi Rum
How does the COVID-19 pandemic reshape the lending behavior of financial institutions?
Get PDFIn this study, I explore the impact of COVID-19 on the lending behavior of traditional and FinTech banks. I use difference-in-difference and triple-diff-in-diff approach with 2019-2020 HMDA loan application data and the Covid Community Vulnerability Index (CVI) to study 1) borrower profiles and loan application demand, 2) lender scrutiny stringency i.e. application approval rates, 3) loan interest rates, and 4) securitization of loans in counties with different level of epidemic vulnerability before and after the epidemic. I find that borrowers in regions with high vulnerability are able to embrace FinTech more quickly. At the same time, FinTech has expanded its previous target demographic to older, non-white, and ethnic minority borrowers. However, the supply side has not softened its application review criteria in response to the surge in demand. Lenders have been more cautious, and while minorities are more willing to apply for FinTech loans, it is worth noting that traditional banks have taken on a social responsibility at this time to increase their lending approval rates for such community. FinTech banks, on the other hand, have expanded the sale of loans, shifting the uncertainty risk to the broad investors
A Study of Existing Professional Insertion Training Programs for Newly-Immigrated Teachers in the Québec School System
Get PDFThe education system in Quebec is currently faced with a paradigm shift. One of these shifts is that the teaching profession attracts less and less people due to several factors; another one is that as the cultural make – up of Quebec society is changing, with more and more students from varied cultural backgrounds attending the schools. One way the Ministry of Education can address both these problems is through the hiring of immigrant teachers – either those with plenty of experience already, or people new to the profession. However, for all the interest shown by immigrant teachers to integrate the Quebec education system, there still seem to be unique obstacles and barriers faced by these willing and ready teachers.
The interpretive phenomenological approach used in this study gives a voice to those people who live the situation under investigation. Through interviews conducted with participants from school centers across the Greater Montreal Region, this study aims to do just that – allow immigrant teachers to tell their own stories and relate their experiences accessing and participating in Professional Insertion Programs in the Quebec school system
Enabling Millimeter Wave Communications for Use Cases of 5G and Beyond Networks
Get PDFThe wide bandwidth requirements of the fifth generation (5G) and beyond networks are driving the move to millimeter wave (mmWave) bands where it can provide a huge increase in the available bandwidth. Increasing the bandwidth is an effective way to improve the channel capacity with limited power. Moreover, the short wavelengths of such bands enable massive number of antennas to be integrated together in small areas. With such massive number of antennas, narrow beamwidth beams can be obtained which in turn can improve the security. Furthermore, the massive number of antennas can help in mitigating the severe path-loss at mmWave frequencies, and realize high data rate communication at reasonable distances. Nevertheless, one of the main bottlenecks of mmWave communications is the signal blockage. This is due to weak diffraction ability and severe penetration losses by many common building materials such as brick, and mortar as well as the losses due to human bodies. Thus, user mobility and/or small movements of obstacles and reflectors cause rapid channel gain variations which leads to unreliable communication links.
The harsh propagation environment at such high frequencies makes it hard to provide a reliable service, hence, maintaining connectivity is one key design challenge in mmWave networks. Relays represent a promising approach to improve mmWave connectivity where they can redirect the signal to avoid the obstacles existing in the propagation environment. However, routing in mmWave networks is known to be a very challenging problem due to the inherent propagation characteristics of mmWave frequencies. Furthermore, inflexible routing technique may worsen network performance and increase scheduling overhead. As such, designing an appropriate transmission routing technique for each service is a crucial issue in mmWave networks. Indeed, multiple factors must be taken into account in the routing process, such as guaranteeing the robustness of network connectivity and providing high data rates.
In this thesis, we propose an analytical framework to investigate the network reliability of mmWave relaying systems for multi-hop transmissions. We also propose a flexible routing technique for mmWave networks, namely the best routing technique. The performance of the proposed routing technique is investigated using tools from stochastic geometry. The obtained results provide useful insights on adjusting the signal noise ratio (SNR) threshold for decode and forward (DF) relay according to the order of the best relay, blockage and relay densities in order to improve spectral efficiency. We also propose a novel mathematical framework to investigate the performance of two appropriate routing techniques for mmWave networks, namely minimum hop count (MHC) and nearest LoS relay to the destination with MHC (NLR-MHC) to support wide range of use cases for 5G and beyond networks. Analytical models are provided to evaluate the performance of the proposed techniques using tools from stochastic geometry. In doing so, we model the distribution of hop count using phase-type distribution, and then we use this distribution to derive analytical results for the coverage probability and spectral efficiency. Capitalizing on the derived results, we introduce a comprehensive study of the effects of different system parameters on the performance of multi-hop mmWave systems. These findings provide important insights for designing multi-hop mmWave networks with better performance.
Furthermore, we adapt the proposed relay selection technique for IoT devices in mmWave relaying systems to prolong the IoT device’s battery life. The obtained results reveal the trade-off between the network connectivity and the energy consumption of IoT devices. Lastly, we have exploited the enormous bandwidth available in the mmWave band to support reliable fronthaul links for cell-free (CF) massive multiple-input multiple-output (MIMO). We provide a comprehensive investigation of different system parameters on the uplink (UL) performance of mmWave fronthaul-based CF mMIMO systems. Results reveal that increasing the access point (AP) density beyond a certain limit would not achieve further improvement in the UL data rates. Also, the higher number of antennas per AP may even cause UL data rates degradation
Cell-Free Massive MIMO: Challenges and Promising Solutions
Get PDFAlong with its primary mission in fulfilling the communication needs of humans as well as intelligent machines, fifth generation (5G) and beyond networks will be a virtual fundamental component for all parts of life, society, and industries. These networks will pave the way towards realizing the individuals’ technological aspirations including holographic telepresence, e-Health, pervasive connectivity in smart environments, massive robotics, three-dimensional unmanned mobility, augmented reality, virtual reality, and internet of everything. This new era of applications brings unprecedented challenging demands to wireless network, such as high spectral efficiency, low-latency, high-reliable communication, and high energy efficiency. One of the major technological breakthroughs that has recently drawn the attention of researchers from academia and industry to cope with these unprecedented demands of wireless networks is the cell-free (CF) massive multiple-input multiple-output (mMIMO) systems. In CF mMIMO, a large number of spatially distributed access points are connected to a central processing unit (CPU). The CPU operates all APs as a single mMIMO network with no cell boundaries to serve a smaller number of users coherently on the same time-frequency resources. The system has shown substantial gains in improving the network performance from different perspectives, especially for cell-edge users, compared it other candidate technologies for 5G networks, \ie co-located mMIMO and small-cell (SC) systems. Nevertheless, the full picture of a practical scalable deployment of the system is not clear yet. In this thesis, we provide more in-depth investigations on the CF mMIMO performance under various practical system considerations. Also, we provide promising solutions to fully realize the potential of CF mMIMO in practical scenarios. In this regard, we focus on three vital practical challenges, namely hardware and channel impairments, malicious attacks, and limited-capacity fronthaul network.
Regarding the hardware and channel impairments, we analyze the CF mMIMO performance under such practical considerations and compare its performance with SC systems. In doing so, we consider that both APs and user equipment (UE)s are equipped with non-ideal hardware components. Also, we consider the Doppler shift effect as a source of channel impairments in dynamic environments with moving users. Then, we derive novel closed-form expressions for the downlink (DL) spectral efficiency of both systems under hardware distortions and Doppler shift effect. We reveal that the effect of non-ideal UEs is more prominent than the non-ideal APs. Also, while increasing the number of deployed non-ideal APs can limit the hardware distortion effect in CF mMIMO systems, this leads to an extra performance loss in SC systems. Besides, we show that the Doppler shift effect is more harsh in SC systems. In addition, the SC system operation is more suitable for low-velocity users, however, it is more beneficial to adopt CF mMIMO system for network operation under high-mobility conditions. Capitalizing on the latter, we propose a hybrid CF mMIMO/SC system that can significantly outperforms both CF mMIMO and SC systems by providing different mobility conditions with high data rates simultaneously.
Towards a further improvement in the CF mMIMO performance under high mobility scenarios, we propose a novel framework to limit the performance degradation due to the Doppler shift effect. To this end, we derive novel expressions for tight lower bound of the average DL and uplink (UL) data rates. Capitalizing on the derived analytical results, we provide an analytical framework that optimizes the frame length to minimize the Doppler shift effect on DL and UL data rates according to some criterion. Our results reveal that the optimal frame lengths for maximizing the DL and UL data rates are different and depend mainly on the users' velocities. Besides, adapting the frame length according to the velocity conditions significantly limits the Doppler shift effect, compared to applying a fixed frame length.
To empower the CF mMIMO systems with secure transmission against malicious attacks, we propose two different approaches that significantly increases the achievable secrecy rates. In the first approach, we introduce a novel secure DL transmission technique that efficiently limits the eavesdropper (Eve) capability in decoding the transmitted signals to legitimate users. Differently, in the second approach, we adopt the distinctive features of Reconfigurable intelligent surfaces (RIS)s to limit the information leakage towards the Eve.
Regarding the impact of limited capacity of wired-based fronthaul links, we drive the achievable DL data rates assuming two different CF mMIMO system operations, namely, distributed and centralized system operations. APs and CPU are the responsible entities for carrying out the signal processing functionalities in the distributed and centralized system operations, respectively. We show that the impact of limited capacity fronthaul links is more prominent on the centralized system operation. In addition, while the distributed system operation is more preferable under low capacities of fronthaul links, the centralized counterpart attains superior performance at high capacities of fronthaul links. Furthermore, considering the distributed and centralized system operations, and towards a practical and scalable operation of CF mMIMO systems, we propose a wireless-based fronthaul network for CF mMIMO systems under three different operations, namely, microwave-based, mmWave-based, and hybrid mmWave/microwave. Our results show that the integration between the centralized operation and the hybrid-based fronthaul network provides the highest DL data rates when APs are empowered with signal decoding capabilities. However, integrating the distributed operation with the microwave-based fronthaul network achieves ultimate performance when APs are not supported with decoding capabilities
An Empirical Study of Runtime Files Attached to Crash Reports
Get PDFWhen a software system crashes, users report the crash using crash report tracking tools. A crash report (CR) is then routed to software developers for review to fix the problem. A CR contain a wealth of information that allow developers to diagnose the root causes of problems and provides fixes. This is particularly important at Ericsson, one of the world’s largest Telecom company, in which this study was conducted. The handling of CRs at Ericsson goes through multiple lines of supports until a solution is provided. To make this possible, Ericsson software engineers and network operators rely on runtime data that is collected during the crash. This data is organized into files that are attached to the CRs. However, not all CRs contain this data in the first place. Software engineers and network operators often have to request additional files after the CR is created and sent to different Ericsson support lines, a problem that often delays the resolution process.
In this thesis, we conduct an empirical study of the runtime files attached to Ericsson CRs. We focus on answering four research questions that revolved around the proportion of runtime files in a selected set of CRs, the relationship between the severity of CRs and the type of files they contain, the impact of different file types on the time to fix the CR, and the possibility to predict whether a CR should have runtime data attached to it at the CR submission time. Our ultimate goal is to understand how runtime data is used during the CR handling process at Ericsson and what recommendations we can make to improve this process
Design and Analysis: Servo-Tube-Powered Liquid Jet Injector for Drug Delivery Applications
Get PDFThe current state of commercially available needle-free liquid jet injectors for drug delivery offers no way of controlling the output pressure of the device in real time, as the driving mechanism for these injectors provides a fixed delivery pressure profile. In order to improve the delivery efficiency as well as the precision of the targeted tissue depth, it is necessary to develop a power source that can accurately control the plunger velocity. The duration of a liquid jet injection can vary from 10 to 100 ms, and it generate acceleration greater than 2 g (where g is the gravity); thus, a platform for real-time control must exhibit a response time greater than 1 kHz and good accuracy. Improving the pioneering work by Taberner and others whereby a Lorentz force actuator based upon a voice coil is designed, this study presents a prototype injector system with greater controllability based on the use of a fully closed-loop control system and a classical three-phase linear motor consisting of three fixed coils and multiple permanent magnets. Apart from being capable of generating jets with a required stagnation pressure of 15–16 MPa for skin penetration and liquid injection, as well as reproducing typical injection dynamics using commercially available injectors, the novelty of this proposed platform is that it is proven to be capable of shaping the real-time jet injection pressure profile, including pulsed injection, so that it can later be tailored for more efficient drug delivery
The re-initiation of cellular detonations downstream of an inert layer
Get PDFThe current work aims to examine how the nature of cellular instabilities controls the re-initiation capability and
dynamics of a gaseous detonation transmitting across a layer of inert (or non-detonable) gases. This canonical
problem is tackled via computational analysis based on the two-dimensional, reactive Euler equations. Two differ-
ent chemical kinetic models were used, a simplified two-step induction-reaction model and a detailed model for
hydrogen-air. For the two-step model, cases with relatively high and low activation energies, representing highly
and weakly unstable cellular detonations, respectively, are considered. For the weakly unstable case, two distinct
types of re-initiation mechanisms were observed. (1) For thin inert layers, at the exit of the layer the detonation
wave front has not fully decayed and thus the transverse waves are still relatively strong. Detonation re-initiation
in the reactive gas downstream of the inert layer occurs at the gas compressed by the collision of the transverse
waves, and thus is referred to as a cellular-instability-controlled re-initiation. (2) If an inert layer is sufficiently
thick, the detonation wave front has fully decayed to a planar shock when it exits the inert layer, and re-initiation
still occurs downstream as a result of planar shock compression only, which is thus referred to as a planar-shock-
induced re-initiation. Between these two regimes there is a transition region where the wave front is not yet fully
planar, and thus perturbations by the transverse waves still play a role in the re-initiation. For the highly unstable
case, re-initiation only occurs via the cellular-instability-controlled mechanisms below a critical thickness of the
inert layer. Additional simulations considering detailed chemical kinetics demonstrate that the critical re-initiation
behaviors of an unstable stoichiometric mixture of hydrogen-air at 1 atm and 295 K are consistent with the finding
from the two-step kinetic model for a highly unstable reactive mixture
Shame and the Scope of Moral Responsibility
Get PDFAccording to Peter Strawson’s reactive attitudes approach toward moral responsibility, reactive attitudes constitute the foundation of moral responsibility. The content of reactive attitudes determines the scope, i.e., its narrowness and broadness, of moral responsibility. When it comes to the question of which moral emotions are identified as reactive attitudes, it is well-accepted by Strawsonians that guilt is a reactive attitude, but many of them deny that shame is a reactive attitude even though shame and guilt are closely related. The main reason for denying shame as a reactive attitude is that they suppose that people are only morally responsible for things within their voluntary control, but people can feel ashamed of things that they have no voluntary control over. This paper argues that those who deny shame as a reactive attitude hold a narrow understanding of reactive attitudes and moral responsibility. The biggest issue underlying this narrow understanding of moral responsibility is that it commits to what Bernard Williams calls “the morality system” and its peculiar assumption, which distorts our ordinary understanding of moral responsibility. Based upon Strawson’s relatively less famous article “Social Morality and Individual Ideal”, this paper then develops an alternative account of reactive attitudes, i.e., reactive attitudes are emotional responses to the violation or fulfillment of social ethical expectations. This new definition of reactive attitudes covers shame as a reactive attitude and promotes a broader understanding of moral responsibility, which reflects our ordinary understanding of moral responsibility
Heidegger, Funerary Practices, and the Fourfold
Get PDFHeidegger famously argues in Being and Time that to live well and honestly, we must face up to our own mortality. Within Being and Time, Heidegger is clear that neither exposure to the deaths of others, nor engagement in funerary practices, bring us closer to death in the proper—“authentic”—sense. In this paper, I take up a hint offered by Johannes Niederhauser in his 2019 book, On Death and Being, that Heidegger amends his original position on funerary practices in his later work. My project is to affirm that this change indeed took place over the course of Heidegger’s career by highlighting his approving reference to the Totenbaum (that is, the coffin) in “Building, Dwelling, Thinking” and his remarks on Sophocles’ Antigone in his lecture course Hölderlin’s Hymn “The Ister”. In turn, I attempt to account for the change in Heidegger’s position by examining funerary practices in light of the thinking of the “fourfold”. Ultimately, I claim that funerary practices may be considered a form of poetry understood in the broad sense of “poetic dwelling”. In the final sections of the paper, I suggest, beyond Heidegger’s own words but in line with his thinking (at least as I interpret it), that the death of others constitutes a potent and universal access point for reflection on Being qua Being, even amidst the profoundly desensitized era of what Heid calls “enframing” (Gestell)