901 research outputs found

    Guided rewriting and constraint satisfaction for parallel GPU code generation

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    Graphics Processing Units (GPUs) are notoriously hard to optimise for manually due to their scheduling and memory hierarchies. What is needed are good automatic code generators and optimisers for such parallel hardware. Functional approaches such as Accelerate, Futhark and LIFT leverage a high-level algorithmic Intermediate Representation (IR) to expose parallelism and abstract the implementation details away from the user. However, producing efficient code for a given accelerator remains challenging. Existing code generators depend on the user input to choose a subset of hard-coded optimizations or automated exploration of implementation search space. The former suffers from the lack of extensibility, while the latter is too costly due to the size of the search space. A hybrid approach is needed, where a space of valid implementations is built automatically and explored with the aid of human expertise. This thesis presents a solution combining user-guided rewriting and automatically generated constraints to produce high-performance code. The first contribution is an automatic tuning technique to find a balance between performance and memory consumption. Leveraging its functional patterns, the LIFT compiler is empowered to infer tuning constraints and limit the search to valid tuning combinations only. Next, the thesis reframes parallelisation as a constraint satisfaction problem. Parallelisation constraints are extracted automatically from the input expression, and a solver is used to identify valid rewriting. The constraints truncate the search space to valid parallel mappings only by capturing the scheduling restrictions of the GPU in the context of a given program. A synchronisation barrier insertion technique is proposed to prevent data races and improve the efficiency of the generated parallel mappings. The final contribution of this thesis is the guided rewriting method, where the user encodes a design space of structural transformations using high-level IR nodes called rewrite points. These strongly typed pragmas express macro rewrites and expose design choices as explorable parameters. The thesis proposes a small set of reusable rewrite points to achieve tiling, cache locality, data reuse and memory optimisation. A comparison with the vendor-provided handwritten kernel ARM Compute Library and the TVM code generator demonstrates the effectiveness of this thesis' contributions. With convolution as a use case, LIFT-generated direct and GEMM-based convolution implementations are shown to perform on par with the state-of-the-art solutions on a mobile GPU. Overall, this thesis demonstrates that a functional IR yields well to user-guided and automatic rewriting for high-performance code generation

    Canada\u27s Evergreen Playground: A History of Snow in Vancouver

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    The City of Vancouver is not as snowy as the rest of Canada; rain, not snow, is its defining weather feature. But snow is a common seasonal occurrence, having fallen there nearly every winter since the 1850s. This dissertation places snow at the centre of the City of Vancouver’s history. It demonstrates how cultural and natural factors influenced human experiences and relationships with snow on the coast between the 1850s and 2000s. Following Vancouver’s incorporation, commercial and civic boosters constructed – and settlers adopted – what I call an evergreen mentality. Snow was reconceptualized as a rare and infrequent phenomenon. The evergreen mentality was not completely false, but it was not entirely true, either. This mindset has framed human relationships with snow in Vancouver ever since. While this idea was consistent, how coastal residents experienced snow evolved in response to societal developments (such as the rise of the automobile and the adoption of new snow-clearing technologies) and regional climate change. I show that the history of snow in Vancouver cannot be fully understood without incorporating the southern Coast Mountains. Snow was a connecting force between the coastal metropolis and mountainous hinterland. Settlers drew snowmelt to the urban environment for its energy potential and life-sustaining properties; snow drew settlers to the mountains for recreation and economic opportunities. Mountain snow became a valuable resource for coastal residents throughout the twentieth century. Human relationships with snow in the mountains were shaped, as they were in the city, by seasonal expectations, societal circumstances, and shifting climate conditions. In charting a history of snow in Vancouver and the southern Coast Mountains, this dissertation clears a new path in Canadian environmental historiography by bringing snow to the historiographical forefront. It does so in an urban space not known for snow, broadening the existing geography of snow historiography. In uncovering snow’s impact on year-round activities, this work also expands the field’s temporal boundaries. Through this work, one sees how snow helped to make Canada’s Evergreen Playground

    The Elusive Pursuit of Justice: Sexual Assault Survivors' Speak About Redress in the Aftermath of Violence

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    The struggle of survivors to obtain justice after they have been sexually assaulted has been a much discussed topic in recent years. Significant attention and resources are being directed towards this issue, making academic research particularly valuable at this time. However, instead of asking how legal processes can theoretically be made better, as is the case in most of the literature on this topic, my focus has been on asking why survivors want to engage in a legal process at all. What do they get from reporting their assaults and does what the legal system offers them respond to what survivors are looking for from justice? This project starts this conversation by asking survivors what they think justice should be in the aftermath of a sexual assault. Using feminist standpoint epistemology and grounded theory, I interviewed sixteen survivors and seven lawyers to explore what justice means for survivors in the aftermath of an assault. From the data, I identified four major themes including: harms and healing, accountability, punishment, and restorative justice. I found that survivors were not satisfied with the justice they could obtain under criminal law. They stated that it was difficult, financially and emotionally, to engage in criminal proceedings that were unlikely to resolve in a way that made them feel as if justice was done. While other forms of legal justice are also available, survivors often found these to be inaccessible as well, or they were unaware of the existence of these alternative options. The survivors I spoke with imagined an expansive ideal of justice. To most of the women I interviewed with, justice involved the prevention of future violence, something they did not think the legal system was currently equipped to deal with. They were curious, though conflicted, about restorative models, but appreciated their focus on attempting to reform offender behaviour. They also stressed the importance of being supported in their attempts to recover from sexual assault, highlighting that financial compensation was crucial for any survivor to heal

    The Mass Exodus of Black Millennials From the Black Church: In Search of Biblical Blackness

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    A mass exodus of Black millennials away from the Black churches of the African diaspora has taken place in recent years. There is a plethora of reasons for this given by the Black millennials, spiritual authors/researchers, and the spiritual leadership of the Black church. The most important of these reasons has been put forward by Black millennials that the Bible and Christianity are irrelevant to the social, economic, and political issues of their lives and they want no part of it. This research is undertaken to investigate the real cause(s) of this exodus and to determine where the responsibility lies to reverse the bleeding of a generation from the pews of our Black churches. The goal of this research is to engage in a project with four professional stakeholders who represent the leadership of the Black church and four non-professional stakeholders who are Black millennials presently attending, and who had been attending, a Black church at some time. This writer will explore the relationship between the Black church and its Black people along with the role the Black church plans to play in the lives of its people by addressing the concerns of Black millennials and examining the legitimacy of their concerns through a biblical lens along with the literature pertaining to these phenomena. Finally, the aim of this work is to prove the Bible and Christianity are both culturally inclusive, by illustrating how the Bible has texts about the Black community and that Black people have always been in the central thoughts of God’s plans and have never been an afterthought. Study shows millennials are still not particularly passionate about the Black church and the Black church has not been preparing herself for the return of the largest generation in U.S. history

    Perspectives on Knowledge and Higher Education within Marginalised Communities in South Africa

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    With increasing calls to decolonise education across the globe, the inclusion of different knowledges in mainstream education has become a priority. Initiatives have included diversifying curriculum content and the creation of modules with a focus on localised knowledge. These initiatives have rarely been undertaken in collaboration with local communities and students, but rather have involved extracting and repurposing local knowledges for mainstream education (Barnhardt & Kawagley, 2008; Shizha,2014; Mkhize & Ndimande-Hlongwa 2014). In South Africa, colonialism, and apartheid systematically marginalised traditional and indigenous ways of producing knowledge. The end of apartheid brought with it a move away from segregated education and new policy emerged to increase the access to higher education. However, many universities remain segregated, which means that students from historically marginalised communities are still attending universities that are under-resourced (Heleta, 2016). The curriculum in many higher education institutions remains Eurocentric, reinforcing Western dominance and privilege. The lack of meaningful decolonisation led to student protests in 2015, which propelled decolonisation and the demand for an Afrocentric curriculum to the forefront of the national debate (Kwoba, Chantiluke & Nkopo, 2018). Through utilising a collaborative approach as part of a decolonising methodology, this study attempts to challenge Eurocentric research methods that can undermine local knowledge and the experiences of marginalised groups. As well as being collective, this approach requires the researcher to critically reflect on their own participation in a research project (Smith, 2002). This research highlights the tensions inherent in meeting the aspirations of a decolonisation agenda and student expectations of the currency afforded by attending a neoliberal higher education institution. The findings of this study add to the critical research base on decolonisation by focusing on indigenous perspectives of received education, their own knowledge, and how this knowledge can/should be used. Furthermore, this research is a recognition of the complexities and contextual considerations necessary when exploring decolonising

    Race, Fantasy & Enjoyment

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    Why has the institution of race remained resilient given what we know about its detrimental impacts? Why do we enjoy race and who has access to that enjoyment? Is black trauma endemic to this enjoyment and can blackness be divorced from it? I hypothesize that we live in an episteme that has transitioned from physiological need to surplus enjoyment. This enjoyment has allowed humans to conceptualize their relations beyond the physical and necessary. Racial enjoyment is psychical because it involves how we enjoy and not how we know (enjoyment v. knowledge). There is a collective investment in race that subtends its primacy. The conservative right winger who is a nationalist is likely to dislike the racial other for easily recognizable tropes and stereotypes. In this way, their relationship to race is easier to parse. My intervention is in the white liberal framework and imaginary, where social activists are embedded in the work. My critique of the liberal left centers their racial enjoyment of blackness as l’objet petit a along the same spectrum as the regressive right. Through a fetishistic disavowal, the white liberal can experience blackness in variety, and vicinity without disrupting the violence that terrorizes black life. This essay will be a critical exploration through a psychoanalytic framework in the Lacanian tradition. My methodology will be ethnographic and interdisciplinary, calling on social, cultural, and political commentary. Sheldon George and Derek Hook have earlier foundational work in this tradition arguing that enjoyment and its perceived theft create kindling for the violence of racial othering. It is not just that the other enjoys, but they enjoy something that prohibits my ability to actualize full enjoyment. The sanction of targeted violence is coded in blackness according to Afropessimist thought. Even at a slightly less extreme level of critique, Fanon and some Marxists still acknowledge blackness is not equated with nor afforded full humanity. The proliferation of images of black death and violability permeate the media sphere, yet blackness is culture, the world over. It is what is hip. And more than ever, the question would you want to be black seems attractive to more nonblacks. The fantasy of race is that it allows the nonblack subject an approximation to black subjectivity that is predicated on abstraction from it. This ability to enjoy the nonbelonging of the racialized other and call that nonbelonging into question by policing the boundaries of what is normative, and deviant create the conditions for acceptance into white Western society

    Leaving it all on the Field? Analysing the Appropriate Scope of Vicarious Liability for Athletes in the Sports Industry

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    This research seeks to address the existing uncertainty surrounding the appropriate theoretical justification for vicarious liability, and it does so by developing and deploying a contextual-pluralist model of employer liability. In recognising that none of the purported rationales for the doctrine are entirely satisfactory on their own, this thesis presents a novel framework of vicarious liability that is sensitive to context, factual nuance and empirical insight. In order to test how this model works in practice, this study examines how it might be applied to the eclectic and ever-developing context of sport. This is the first work to provide an in-depth analysis of vicarious liability in the sporting industry, and it draws upon a variety of different sports at numerous levels of expertise. As such, it explores how a more theoretically informed model of vicarious liability might lead to some amateur sports clubs being held strictly liable for the torts of their players. Similarly, it also demonstrates how other entities in professional sport – such as national governing bodies and competition organisers – may also be held vicariously liable for the wrongful behaviour of athletes that compete under their auspices. Furthermore, and in assessing what functions are inherent in an athlete’s employment, this thesis additionally analyses the extent to which sporting employers should be held liable for a variety of personal and non-personal on-the-field injuries. In recognising the broader off-the-field responsibilities of many professional athletes, this study also discusses whether clubs and governing bodies ought to be held vicariously liable for sexual violence committed by their star athletes. In applying my theoretical and socio-legal model of liability to these various contexts, this thesis aims to illustrate what broader lessons we might learn about vicarious liability from a sport-specific analysis. It also seeks to highlight some practical recommendations for sporting stakeholders to implement

    Perceptually Motivated, Intelligent Audio Mixing Approaches for Hearing Loss

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    The growing population of listeners with hearing loss, along with the limitations of current audio enhancement solutions, have created the need for novel approaches that take into consideration the perceptual aspects of hearing loss, while taking advantage of the benefits produced by intelligent audio mixing. The aim of this thesis is to explore perceptually motivated intelligent approaches to audio mixing for listeners with hearing loss, through the development of a hearing loss simulation and its use as a referencing tool in automatic audio mixing. To achieve this aim, a real-time hearing loss simulation was designed and tested for its accuracy and effectiveness through the conduction of listening studies with participants with real and simulated hearing loss. The simulation was then used by audio engineering students and professionals during mixing, in order to provide information on the techniques and practices used by engineers to combat the effects of hearing loss while mixing content through the simulation. The extracted practices were then used to inform the following automatic mixing approaches: a deep learning approach utilising a differentiable digital signal processing architecture, a knowledge-based approach to gain mixing utilising fuzzy logic, a genetic algorithm approach to equalisation and finally a combined system of the fuzzy mixer and genetic equaliser. The outputs of all four systems were analysed, and each approach’s strengths and weaknesses were discussed in the thesis. The results of this work present the potential of integrating perceptual information into intelligent audio mixing production for hearing loss, paving the way for further exploration of this approach’s capabilities
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