17,275 research outputs found
Meso-scale FDM material layout design strategies under manufacturability constraints and fracture conditions
In the manufacturability-driven design (MDD) perspective, manufacturability of the product or system is the most important of the design requirements. In addition to being able to ensure that complex designs (e.g., topology optimization) are manufacturable with a given process or process family, MDD also helps mechanical designers to take advantage of unique process-material effects generated during manufacturing. One of the most recognizable examples of this comes from the scanning-type family of additive manufacturing (AM) processes; the most notable and familiar member of this family is the fused deposition modeling (FDM) or fused filament fabrication (FFF) process. This process works by selectively depositing uniform, approximately isotropic beads or elements of molten thermoplastic material (typically structural engineering plastics) in a series of pre-specified traces to build each layer of the part. There are many interesting 2-D and 3-D mechanical design problems that can be explored by designing the layout of these elements. The resulting structured, hierarchical material (which is both manufacturable and customized layer-by-layer within the limits of the process and material) can be defined as a manufacturing process-driven structured material (MPDSM). This dissertation explores several practical methods for designing these element layouts for 2-D and 3-D meso-scale mechanical problems, focusing ultimately on design-for-fracture. Three different fracture conditions are explored: (1) cases where a crack must be prevented or stopped, (2) cases where the crack must be encouraged or accelerated, and (3) cases where cracks must grow in a simple pre-determined pattern. Several new design tools, including a mapping method for the FDM manufacturability constraints, three major literature reviews, the collection, organization, and analysis of several large (qualitative and quantitative) multi-scale datasets on the fracture behavior of FDM-processed materials, some new experimental equipment, and the refinement of a fast and simple g-code generator based on commercially-available software, were developed and refined to support the design of MPDSMs under fracture conditions. The refined design method and rules were experimentally validated using a series of case studies (involving both design and physical testing of the designs) at the end of the dissertation. Finally, a simple design guide for practicing engineers who are not experts in advanced solid mechanics nor process-tailored materials was developed from the results of this project.U of I OnlyAuthor's request
A Design Science Research Approach to Smart and Collaborative Urban Supply Networks
Urban supply networks are facing increasing demands and challenges and thus constitute a relevant field for research and practical development. Supply chain management holds enormous potential and relevance for society and everyday life as the flow of goods and information are important economic functions. Being a heterogeneous field, the literature base of supply chain management research is difficult to manage and navigate. Disruptive digital technologies and the implementation of cross-network information analysis and sharing drive the need for new organisational and technological approaches. Practical issues are manifold and include mega trends such as digital transformation, urbanisation, and environmental awareness.
A promising approach to solving these problems is the realisation of smart and collaborative supply networks. The growth of artificial intelligence applications in recent years has led to a wide range of applications in a variety of domains. However, the potential of artificial intelligence utilisation in supply chain management has not yet been fully exploited. Similarly, value creation increasingly takes place in networked value creation cycles that have become continuously more collaborative, complex, and dynamic as interactions in business processes involving information technologies have become more intense.
Following a design science research approach this cumulative thesis comprises the development and discussion of four artefacts for the analysis and advancement of smart and collaborative urban supply networks. This thesis aims to highlight the potential of artificial intelligence-based supply networks, to advance data-driven inter-organisational collaboration, and to improve last mile supply network sustainability. Based on thorough machine learning and systematic literature reviews, reference and system dynamics modelling, simulation, and qualitative empirical research, the artefacts provide a valuable contribution to research and practice
People make Places
For centuries Glasgow, as a bucolic fishing village and ecclesiastical centre on the banks of the River Clyde, held little of strategic significance. When success and later threats came to the city, it was as a consequence of explosive growth during the industrial era that left a significant civic presence accompanied by social and environmental challenges. Wartime damage to the fabric of the city and the subsequent implementation of modernist planning left Glasgow with a series of existential threats to the lives and the health of its people that have taken time to understand and come to terms with.
In a few remarkable decades of late 20th century regeneration, Glasgow began to be put back together. The trauma of the second half of the 20th century is fading but not yet a distant memory. Existential threats from the climate emergency can provoke the reaction “what, again?” However, the resilience built over the last 50 years has instilled a belief that a constructive, pro-active and creative approach to face this challenge along with the recognition that such action can be transformational for safeguarding and improving people’s lives and the quality of their places. A process described as a just transition that has become central to Glasgow’s approach.
Of Scotland’s four big cities, three are surrounded by landscape and sea only Glasgow is surrounded by itself. Even with a small territory, Glasgow is still the largest of Scotland’s big cities and by some margin. When the wider metropolitan area is considered, Glasgow is – like Birmingham, Manchester and Liverpool – no mean city.
People make Places begins with a review of the concept and complexities of place, discusses why these matter and reviews the growing body of evidence that place quality can deliver economic, social and environmental value. The following chapters focus on the history and evolution of modern Glasgow in four eras of 19th and early 20th century industrialisation, de- industrialisation and modernism in mid 20th century, late 20th century regeneration and a 21st century recovery towards transition and renaissance, and document the process, synthesis and the results of a major engagement programme and to explore systematic approaches to place and consensus building around the principal issues.
The second half of the work reflects on a stocktaking of place in contemporary Glasgow, looking at the city through the lenses of an international, metropolitan and everyday city, concluding with a review of the places of Glasgow and what may be learned from them revealing some valuable insights presented in a series of Place Stories included.
The concluding chapter sets out the findings of the investigation and analysis reviewing place goals, challenges and opportunities for Glasgow over the decades to 2030 and 2040 and ends with some recommendations about what Glasgow might do better to combine place thinking and climate awareness and setting out practical steps to mobilise Glasgow’s ‘place ecosystem’
Quantum Annealing for Single Image Super-Resolution
This paper proposes a quantum computing-based algorithm to solve the single
image super-resolution (SISR) problem. One of the well-known classical
approaches for SISR relies on the well-established patch-wise sparse modeling
of the problem. Yet, this field's current state of affairs is that deep neural
networks (DNNs) have demonstrated far superior results than traditional
approaches. Nevertheless, quantum computing is expected to become increasingly
prominent for machine learning problems soon. As a result, in this work, we
take the privilege to perform an early exploration of applying a quantum
computing algorithm to this important image enhancement problem, i.e., SISR.
Among the two paradigms of quantum computing, namely universal gate quantum
computing and adiabatic quantum computing (AQC), the latter has been
successfully applied to practical computer vision problems, in which quantum
parallelism has been exploited to solve combinatorial optimization efficiently.
This work demonstrates formulating quantum SISR as a sparse coding optimization
problem, which is solved using quantum annealers accessed via the D-Wave Leap
platform. The proposed AQC-based algorithm is demonstrated to achieve improved
speed-up over a classical analog while maintaining comparable SISR accuracy.Comment: Accepted to IEEE/CVF CVPR 2023, NTIRE Challenge and Workshop. Draft
info: 10 pages, 6 Figures, 2 Table
A Decision Support System for Economic Viability and Environmental Impact Assessment of Vertical Farms
Vertical farming (VF) is the practice of growing crops or animals using the vertical dimension via multi-tier racks or vertically inclined surfaces. In this thesis, I focus on the emerging industry of plant-specific VF. Vertical plant farming (VPF) is a promising and relatively novel practice that can be conducted in buildings with environmental control and artificial lighting. However, the nascent sector has experienced challenges in economic viability, standardisation, and environmental sustainability. Practitioners and academics call for a comprehensive financial analysis of VPF, but efforts are stifled by a lack of valid and available data.
A review of economic estimation and horticultural software identifies a need for a decision support system (DSS) that facilitates risk-empowered business planning for vertical farmers. This thesis proposes an open-source DSS framework to evaluate business sustainability through financial risk and environmental impact assessments. Data from the literature, alongside lessons learned from industry practitioners, would be centralised in the proposed DSS using imprecise data techniques. These techniques have been applied in engineering but are seldom used in financial forecasting. This could benefit complex sectors which only have scarce data to predict business viability.
To begin the execution of the DSS framework, VPF practitioners were interviewed using a mixed-methods approach. Learnings from over 19 shuttered and operational VPF projects provide insights into the barriers inhibiting scalability and identifying risks to form a risk taxonomy. Labour was the most commonly reported top challenge. Therefore, research was conducted to explore lean principles to improve productivity.
A probabilistic model representing a spectrum of variables and their associated uncertainty was built according to the DSS framework to evaluate the financial risk for VF projects. This enabled flexible computation without precise production or financial data to improve economic estimation accuracy. The model assessed two VPF cases (one in the UK and another in Japan), demonstrating the first risk and uncertainty quantification of VPF business models in the literature. The results highlighted measures to improve economic viability and the viability of the UK and Japan case.
The environmental impact assessment model was developed, allowing VPF operators to evaluate their carbon footprint compared to traditional agriculture using life-cycle assessment. I explore strategies for net-zero carbon production through sensitivity analysis. Renewable energies, especially solar, geothermal, and tidal power, show promise for reducing the carbon emissions of indoor VPF. Results show that renewably-powered VPF can reduce carbon emissions compared to field-based agriculture when considering the land-use change.
The drivers for DSS adoption have been researched, showing a pathway of compliance and design thinking to overcome the ‘problem of implementation’ and enable commercialisation. Further work is suggested to standardise VF equipment, collect benchmarking data, and characterise risks. This work will reduce risk and uncertainty and accelerate the sector’s emergence
Animating potential for intensities and becoming in writing: challenging discursively constructed structures and writing conventions in academia through the use of storying and other post qualitative inquiries
Written for everyone ever denied the opportunity of fulfilling their academic potential, this is ‘Chloe’s story’. Using composite selves, a phrase chosen to indicate multiplicities and movement, to story both the initial event leading to ‘Chloe’s’ immediate withdrawal from a Further Education college and an imaginary second chance to support her whilst at university, this Deleuzo-Guattarian (2015a) ‘assemblage’ of post qualitative inquiries offers challenge to discursively constructed structures and writing conventions in academia. Adopting a posthuman approach to theorising to shift attention towards affects and intensities always relationally in action in multiple ‘assemblages’, these inquiries aim to decentre individual ‘lecturer’ and ‘student’ identities. Illuminating movements and moments quivering with potential for change, then, hoping thereby to generate second chances for all, different approaches to writing are exemplified which trouble those academic constraints by fostering inquiry and speculation: moving away from ‘what is’ towards ‘what if’.
With the formatting of this thesis itself also always troubling the rigid Deleuzo-Guattarian (2015a) ‘segmentary lines’ structuring orthodox academic practice, imbricated in these inquiries are attempts to exemplify Manning’s (2015; 2016) ‘artfulness’ through shifts in thinking within and around an emerging PhD thesis. As writing resists organising, the verb thesisising comes into play to describe the processes involved in creating this always-moving thesis. Using ‘landing sites’ (Arakawa and Gins, 2009) as a landscaping device, freely creating emerging ‘lines of flight’ (Deleuze and Guattari, 2015a) so often denied to students forced to adhere to strict academic conventions, this ‘movement-moving’ (Manning, 2014) opens up opportunities for change as in Manning’s (2016) ‘research-creation’. Arguing for a moving away from writing-representing towards writing-inquiring, towards a writing ‘that does’ (Wyatt and Gale, 2018: 127), and toward writing as immanent doing, it is hoped to animate potential for intensities and becoming in writing, offering opportunities and glimmerings of the not-yet-known
On the Mechanism of Building Core Competencies: a Study of Chinese Multinational Port Enterprises
This study aims to explore how Chinese multinational port enterprises (MNPEs) build
their core competencies. Core competencies are firms’special capabilities and sources
to gain sustainable competitive advantage (SCA) in marketplace, and the concept led
to extensive research and debates. However, few studies include inquiries about the
mechanisms of building core competencies in the context of Chinese MNPEs.
Accordingly, answers were sought to three research questions:
1. What are the core competencies of the Chinese MNPEs?
2. What are the mechanisms that the Chinese MNPEs use to build their core
competencies?
3. What are the paths that the Chinese MNPEs pursue to build their resources bases?
The study adopted a multiple-case study design, focusing on building mechanism of
core competencies with RBV. It selected purposively five Chinese leading MNPEs
and three industry associations as Case Companies.
The study revealed three main findings. First, it identified three generic core
competencies possessed by Case Companies, i.e., innovation in business models and
operations, utilisation of technologies, and acquisition of strategic resources. Second,
it developed the conceptual framework of the Mechanism of Building Core
Competencies (MBCC), which is a process of change of collective learning in
effective and efficient utilization of resources of a firm in response to critical events.
Third, it proposed three paths to build core competencies, i.e., enhancing collective
learning, selecting sustainable processes, and building resource base.
The study contributes to the knowledge of core competencies and RBV in three ways:
(1) presenting three generic core competencies of the Chinese MNPEs, (2) proposing
a new conceptual framework to explain how Chinese MNPEs build their core
competencies, (3) suggesting a solid anchor point (MBCC) to explain the links among
resources, core competencies, and SCA. The findings set benchmarks for Chinese
logistics industry and provide guidelines to build core competencies
Gasificação direta de biomassa para produção de gás combustível
The excessive consumption of fossil fuels to satisfy the world necessities of
energy and commodities led to the emission of large amounts of greenhouse
gases in the last decades, contributing significantly to the greatest
environmental threat of the 21st century: Climate Change. The answer to this
man-made disaster is not simple and can only be made if distinct stakeholders
and governments are brought to cooperate and work together. This is
mandatory if we want to change our economy to one more sustainable and
based in renewable materials, and whose energy is provided by the eternal
nature energies (e.g., wind, solar). In this regard, biomass can have a main role
as an adjustable and renewable feedstock that allows the replacement of fossil
fuels in various applications, and the conversion by gasification allows the
necessary flexibility for that purpose. In fact, fossil fuels are just biomass that
underwent extreme pressures and heat for millions of years. Furthermore,
biomass is a resource that, if not used or managed, increases wildfire risks.
Consequently, we also have the obligation of valorizing and using this
resource.
In this work, it was obtained new scientific knowledge to support the
development of direct (air) gasification of biomass in bubbling fluidized bed
reactors to obtain a fuel gas with suitable properties to replace natural gas in
industrial gas burners. This is the first step for the integration and development
of gasification-based biorefineries, which will produce a diverse number of
value-added products from biomass and compete with current petrochemical
refineries in the future. In this regard, solutions for the improvement of the raw
producer gas quality and process efficiency parameters were defined and
analyzed. First, addition of superheated steam as primary measure allowed the
increase of H2 concentration and H2/CO molar ratio in the producer gas without
compromising the stability of the process. However, the measure mainly
showed potential for the direct (air) gasification of high-density biomass (e.g.,
pellets), due to the necessity of having char accumulation in the reactor bottom
bed for char-steam reforming reactions. Secondly, addition of refused derived
fuel to the biomass feedstock led to enhanced gasification products, revealing
itself as a highly promising strategy in terms of economic viability and
environmental benefits of future gasification-based biorefineries, due to the
high availability and low costs of wastes. Nevertheless, integrated techno economic and life cycle analyses must be performed to fully characterize the
process. Thirdly, application of low-cost catalyst as primary measure revealed
potential by allowing the improvement of the producer gas quality (e.g., H2 and
CO concentration, lower heating value) and process efficiency parameters with
distinct solid materials; particularly, the application of concrete, synthetic
fayalite and wood pellets chars, showed promising results. Finally, the
economic viability of the integration of direct (air) biomass gasification
processes in the pulp and paper industry was also shown, despite still lacking
interest to potential investors. In this context, the role of government policies
and appropriate economic instruments are of major relevance to increase the
implementation of these projects.O consumo excessivo de combustíveis fósseis para garantir as necessidades e
interesses da sociedade conduziu à emissão de elevadas quantidades de
gases com efeito de estufa nas últimas décadas, contribuindo
significativamente para a maior ameaça ambiental do século XXI: Alterações
Climáticas. A solução para este desastre de origem humana é de caráter
complexo e só pode ser atingida através da cooperação de todos os governos
e partes interessadas. Para isto, é obrigatória a criação de uma bioeconomia
como base de um futuro mais sustentável, cujas necessidades energéticas e
materiais sejam garantidas pelas eternas energias da natureza (e.g., vento,
sol). Neste sentido, a biomassa pode ter um papel principal como uma matéria prima ajustável e renovável que permite a substituição de combustíveis fósseis
num variado número de aplicações, e a sua conversão através da gasificação
pode ser a chave para este propósito. Afinal, na prática, os combustíveis
fósseis são apenas biomassa sujeita a elevada temperatura e pressão durante
milhões de anos. Além do mais, a gestão eficaz da biomassa é fundamental
para a redução dos riscos de incêndio florestal e, como tal, temos o dever de
utilizar e valorizar este recurso.
Neste trabalho, foi obtido novo conhecimento científico para suporte do
desenvolvimento das tecnologias de gasificação direta (ar) de biomassa em
leitos fluidizados borbulhantes para produção de gás combustível, com o
objetivo da substituição de gás natural em queimadores industriais. Este é o
primeiro passo para o desenvolvimento de biorrefinarias de gasificação, uma
potencial futura indústria que irá providenciar um variado número de produtos
de valor acrescentado através da biomassa e competir com a atual indústria
petroquímica. Neste sentido, foram analisadas várias medidas para a melhoria
da qualidade do gás produto bruto e dos parâmetros de eficiência do processo.
Em primeiro, a adição de vapor sobreaquecido como medida primária permitiu
o aumento da concentração de H2 e da razão molar H2/CO no gás produto sem
comprometer a estabilidade do processo. No entanto, esta medida somente
revelou potencial para a gasificação direta (ar) de biomassa de alta densidade
(e.g., pellets) devido à necessidade da acumulação de carbonizados no leito
do reator para a ocorrência de reações de reforma com vapor. Em segundo, a
mistura de combustíveis derivados de resíduos e biomassa residual florestal
permitiu a melhoria dos produtos de gasificação, constituindo desta forma uma
estratégia bastante promissora a nível económico e ambiental, devido à
elevada abundância e baixo custo dos resíduos urbanos. Contudo, devem ser
efetuadas análises técnico-económicas e de ciclo de vida para a completa
caraterização do processo. Em terceiro, a aplicação de catalisadores de baixo
custo como medida primária demonstrou elevado potencial para a melhoria do
gás produto (e.g., concentração de H2 e CO, poder calorífico inferior) e para o
incremento dos parâmetros de eficiência do processo; em particular, a
aplicação de betão, faialite sintética e carbonizados de pellets de madeira,
demonstrou resultados promissores. Finalmente, foi demonstrada a viabilidade
económica da integração do processo de gasificação direta (ar) de biomassa
na indústria da pasta e papel, apesar dos parâmetros determinados não serem
atrativos para potenciais investidores. Neste contexto, a intervenção dos
governos e o desenvolvimento de instrumentos de apoio económico é de
grande relevância para a implementação destes projetos.Este trabalho foi financiado pela The Navigator Company e por Fundos Nacionais através da Fundação para a Ciência e a Tecnologia (FCT).Programa Doutoral em Engenharia da Refinação, Petroquímica e Químic
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Antecedents of business intelligence system use
This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.Organisational reliance on information has become vital for organisational competitiveness. With increasing data volumes, Business Intelligence (BI) becomes a cornerstone of the decision-support system. However, employee resistance to use Business Intelligence Systems (BIS) is evident. This creates a problem to organisations in realising the benefits of BIS. It is thus important to study the enablers of sustained use of BIS amongst employees.
This thesis identifies existing theories that can be used to study BI system use. It integrates and extends technology use theories through a framework focusing on Business Intelligence System Use (BISU). Empirical research is then conducted in Kuwait’s telecom and banking industries through a close-ended, self-administered questionnaire using a five-point Likert scale. Responses were received from 211 BI users. The data was analysed using SmartPLS to study the convergent and discriminant validity and reliability. Partial least squares structural equation modelling (PLS-SEM) was used to study the direct and indirect relationships between constructs and answer the hypotheses. In addition to SmartPLS, SPSS was used for descriptive analysis.
The results indicated that UTAUT factors consisting of performance expectancy, effort expectancy and social influence positively impact BI system use. Voluntariness of use was found to positively moderate the relationship between social influence and BI system use. Furthermore, BI system quality positively impacts both performance expectancy and effort expectancy. The BI user’s self-efficacy also positively impacts effort expectancy. In addition, social influence was found to be positively influenced by organisational factors, namely top management support and information culture.
The findings of this research contribute to literature by determining and quantifying the factors that influence BISU through the lens of employee perspectives. This thesis also explains how employees’ object-based beliefs about BI affect their behavioural beliefs, which in turn impact BISU. Limitations of this research include the omission of UTAUT’s facilitating conditions and the limited variance of respondent demographics
Metaphors of London fog, smoke and mist in Victorian and Edwardian Art and Literature
Julian Wolfreys has argued that after 1850 writers employed stock images of the city without allowing them to transform their texts. This thesis argues, on the contrary, that metaphorical uses of London fog were complex and subtle during the Victorian and Edwardian periods, at least until 1914. Fog represented, in particular, formlessness and the dissolution of boundaries. Examining the idea of fog in literature, verse, newspaper accounts and journal articles, as well as in the visual arts, as part of a common discourse about London and the state of its inhabitants, this thesis charts how the metaphorical appropriation of this idea changed over time. Four of Dickens's novels are used to track his use of fog as part of a discourse of the natural and unnatural in individual and society, identifying it with London in progressively more negative terms. Visual representations of fog by Constable, Turner, Whistler, Monet, Markino, O'Connor, Roberts and Wyllie and Coburn showed an increasing readiness to engage with this discourse. Social tensions in the city in the 1880s were articulated in art as well as in fiction. Authors like Hay and Barr showed the destruction of London by its fog because of its inhabitants' supposed degeneracy. As the social threat receded, apocalyptic scenarios gave way to a more optimistic view in the work of Owen and others. Henry James used fog as a metaphorical representation of the boundaries of gendered behaviour in public, and the problems faced by women who crossed them. The dissertation also examines fog and individual transgression, in novels and short stories by Lowndes, Stevenson, Conan Doyle and Joseph Conrad. After 1914, fog was no more than a crude signifier of Victorian London in literature, film and, later, television, deployed as a cliche instead of the subtle metaphorical idea discussed in this thesis
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