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Resolving full-wave through-wall transmission effects in multi-static synthetic aperture radar
Get PDFThrough-wall synthetic aperture radar (SAR) imaging is of significant interest for security purposes, in particular when using multi-static SAR systems consisting of multiple distributed radar transmitters and receivers to improve resolution and the ability to recognise objects. Yet there is a significant challenge in forming focused, useful images due to multiple scattering effects through walls, whereas standard SAR imaging has an inherent single scattering assumption. This may be exacerbated with multi-static collections, since different scattering events will be observed from each angle and the data may not coherently combine well in a naive manner. To overcome this, we propose an image formation method which resolves full-wave effects through an approximately known wall or other arbitrary obstacle, which itself has some unknown 'nuisance' parameters that are determined as part of the reconstruction to provide well focused images. The method is more flexible and realistic than existing methods which treat a single wall as a flat layered medium, whilst being significantly computationally cheaper than full-wave methods, strongly motivated by practical considerations for through-wall SAR.Engineering and Physical Sciences Research Council (EPSRC)Inverse Problem
Knowledge transfer in Digital Twins: the methodology to develop Cognitive Digital Twins
Get PDFIn the realm of Digital Twins (DTs), industry experts have emphasised the pivotal concept of the Federation of Twins, envisioning seamless collaboration across sectors driven by shared semantics. In response to this challenge, the Cognitive Digital Twin (CDT) integrates the DT framework with formal semantics, specifically ontologies. This paper introduces a comprehensive five-step methodology for CDT development. Furthermore, it becomes possible to incorporate human expertise into the DT ecosystem by adopting an ontological approach. The CDT enhances DT services with advanced reasoning capabilities, leading to a profound semantic enrichment of the data. The presented methodology has been validated using a use case where the CDT is employed to detect malfunctions, significantly reducing manual intervention. This paper advocates for the adoption of CDTs, which represent a harmonious fusion of formal semantics and human expertise, enhancing system efficiency and operational performance.CIRP Journal of Manufacturing Science and Technolog
Using a paradox lens: a study into the challenges facing an established Servitization provider.
Get PDFThe current zeitgeist for servitization within manufacturing emphasises the need for manufacturers to
balance the contradicting demands of production and service elements in the effort to deliver
customised solutions. This emphasis on juxtapositioning two contradictory logics can however result in
competing intra-organisational demands which are not always capable of a finite solution, often
resulting in tensions and conflictions many managers struggle to navigate. Using a case study
methodology this study identifies frequent and critical challenges facing an established servitization
manufacturer and challenges the traditional binary “either/or” approach to their solution by viewing
the challenges through a paradox lens to highlight their often simultaneous, interconnected, and
interrelated nature and offering paradox theory as an alternative narrative to reframe such tensions.
The conceptualisation of paradoxes within organisational challenges has remained relatively
unexamined in servitization studies, resulting in an oversimplification of underlying challenges facing
manufacturer’s delivering a servitization strategy.
The study applies an exploratory, holistic single case design utilising semi-structured interviews to
explore challenges experienced by 31 senior managers; employing paradox theory as a conceptual
lens to better understand the contextual particulars individuals were drawing on to describe and
construct their experiences of intra-organisational challenges. The study then undertakes a
comparative analysis of extant literature against empirical data from the case study to identify which
challenges present in the case study appear recursive and identifies what tensions within them
contribute to such an outcome.
The study generated five key insights at the individual level of analysis. First, the empirical confirmation
of a conceptual typology presenting a holistic and contextual model that captured the challenges facing
an established servitization organisation, as observed from its own senior management’s perceptions.
Second, the identification of ten recursive challenges. Third, the analysis of the recursive challenges
resulted in the identification of ten paradoxical tensions as causal agents underpinning their cyclical
nature and are not currently associated with the servitization perspective. Fourth, the observation that
the recursive tensions are interconnected and interrelated often spurring other paradoxical tensions;
and fifth, paradoxical tensions contain within them multiple temporal dimensions which can affect the
nature not only of the tension but actors perceptions; again, this is a view not associated with
servitization studies.
The study offers four theoretical contributions to knowledge. First, the study extends the servitization
knowledge base by addressing its lack of contributions from paradox theory. Second, the study
challenges the traditional simplistic assumptions concerning servitization challenges arguing that such
generalisations to be deeply flawed and lacking contextual understanding. Third, the study identified
ten recursive challenges with ten novel tensions acting as causal agents for their sustainment and
identifying such tensions as interconnected and interrelated; thus, can spur other tensions. Finally, the
study introduces a novel perspective in discussing servitization challenges by introducing how socially
constructed temporal perspectives can not only shape an individual’s perspective on challenges
identified but also shape their responses.PhD in Leadership and Managemen
Soil bioengineering for sustainable bioremediation of oil contaminated soils
Get PDFCoulon, Frederic - Associate SupervisorContaminated soils arising from the petroleum industry remains a major problem globally,
resulting in levels of petroleum hydrocarbons and metals that are dangerous to the environment.
Modern remediation strategies focus on sustainability, thus maximizing environmental, social,
and economic benefits. The use of materials derived from agricultural and industrial waste, for
example biochar and spent mushroom compost (SMC), may provide a potential solution to
sustainable remediation strategies. Biochar has numerous properties, e.g., high surface area and
pore volume that may provide benefits to the remediation industry. SMC, a by-product of
mushroom production, may contain diverse groups of microorganisms and extracellular
enzymes important for the biotransformation of contaminants. Biochar and spent mushroom
compost interactions in soil may induces diverse responses in microbial species leading to
changes in soil enzyme activity, reshaping of microbial community structure and consequent
enhancement of contaminants transformations. However, the mechanisms underlying these
interactions are poorly understood, with unpredictable outcomes. There is a deficit of research
designed to understand their collective response on soil fungi and the subsequent benefits to
remediation success. Research needs to focus on the benefits of biochar towards affecting
contaminant bioavailability of multiple rather than single contaminants. Combining biochar
with SMC may facilitate the biodegradation of petroleum hydrocarbons in saline soils. The aim
of the research was to develop a biotechnological approach for the best use of biochar and SMC
to promote microbial remediation of soil contaminated with complex chemical mixture
contaminants (hydrocarbons and heavy metals). It provides a mechanistic understanding of the
physicochemical and biological parameters influencing the remediation approach. The study
further sheds light into the influence of low carbon soil amendment on the behaviour and fate
of heavy metal(loids) and petroleum hydrocarbons, and the underlying microbial community
responses in a genuinely contaminated soil in a four-month microcosms study, and in crude oil
and salt spiked soil in another four-month microcosms study.PhD in Environment and Agrifoo
Influencing factors and mechanisms of local government green development behaviour: evidence from China
Get PDFLonghurst, Philip - Associate SupervisorGreen development has become an important strategy for local governments to
achieve greater sustainability, and adopting green development behaviours has
significant implications for local governments in addressing the relationship
between the environment and the economy. Previous research demonstrated
that the unique characteristics of green development practices have received
considerable attention from scholars. Most studies have highlighted green
development practices in the private sector, although the adoption of green
development practices in the public sector remains understudied. Current
research on green development behaviour in the public sector primarily reflects,
at the individual level, the green behaviour of employees and, at the
organisational level, the green purchasing behaviour of a particular government
department. The discussion of local government green development behaviour
is not predominant. Therefore, this thesis proposes that a detailed understanding
of the processes and specific practices of local government green development
behaviours may be essential for local governments to improve the effectiveness
of implementing sustainable practices.
Although existing studies have addressed the influencing factors that lead to the
adoption of sustainable development by local governments, there needs to be a
more systematic theoretical analysis of the underlying mechanisms adopted by
local governments to achieve green development behaviours. Accordingly, this
thesis aims to explore the factors that influence the implementation of green
development behaviours by local governments and the mechanisms of influence
between the factors. This study draws on mixed methods to develop two studies.
The first is a qualitative study that explores local government green development
behaviour and its influencing factors. It applies various data collection methods,
including semi-structured interviews and document analysis. Fifty-three officials
from local government departments related to green development in China’s
Jiangsu province were interviewed, and the data were analysed using a grounded
theory method. The second is a quantitative study. Seven hundred twenty-two
valid questionnaires were collected, and the model proposed in the first study
with Structural Equation Modelling (SEM). The findings illustrate how the
interactions between various factors shape the green development behaviour of
local governments.
The main findings show that: (1) local government green development behaviour
is a kind of behavioural change, which can be divided into local government green
development policy formulation and implementation. (2) The three main
influences on local governments’ green development behaviours include internal
driving factors, external environmental pressures, and the basis of regional green
development. (3) Internal driving factors and external environmental pressure can
influence local governments’ green development behaviours. (4) Internal driving
factors mediate the relationship between external environmental pressure and
green development behaviour. The basis of regional green development has a
moderating effect on the relationship between internal driving factors and green
development behaviours, as well as the relationship between external
environmental pressures and green development behaviours.
This thesis provides a framework that supports local government behaviour's
decision-making process on the managerial implications. Paper I analyses the
specific processes and practices of local government green development
behaviour, Paper II constructs a theoretical model of local government green
development behaviour, and Paper III examines the mechanisms by which
various factors influence local green development behaviour. At a broader level,
this thesis enriches and expands the research content of sustainable practices in
the public sector. It also provides novel insights for local governments to
formulate effective green development policies, which will help them develop
green development directions and implement green development behaviours to
promote more remarkable sustainable development in the region.PhD in Desig
A review of state-of-the-art 6D pose estimation and its applications in space operations
Get PDFIncrease in autonomous systems now requires for these systems to work in close proximity of other objects in their environments, with many tasks that need to be done on environment objects for eg., assembly, transportation, rendezvous, docking, or to avoid them like collision detections/avoidance, path planning etc. In this literature review we discuss machine learning based algorithms that solve the first step of vision-based autonomous systems i.e., vision based pose estimation. This paper presents a critical review in advancements of 6D pose estimation using both 2D and 3D input data, and compare how they deal with the challenges shared by the computer-vision based localisation problem. We also look over algorithms with their applications in space based tasks like in-orbit docking, rendezvous and the challenges that come with space-vision applications. To conclude the review we also highlight niche problems and possible avenues for future research.2024 CEAS EuroGNC conferenc
Data Set for Comparative Analysis of Blast Prediction Software for Far-Field Shock Wave Effects Behind a Blast Wall
No full textA comparative analysis of blast prediction software for far-field shock wave effects behind a blast wall. Performed using Autodyn, BlastFoam, ProSAir, Viper::Blast and WALAIR++. The resulting software setup file examples are included here.A comparative analysis of blast prediction software for far-field shock wave effects behind a blast wall. Performed using Autodyn, BlastFoam, ProSAir, Viper::Blast and WALAIR++. The resulting software setup file examples are included here.DNV Services UK Lt
Design and implementation of multi-configuration rolling machine
Get PDFFor decades, metal corrugated sheets have usually been manufactured using conventional roll-forming machines with lower and upper rollers or a die and a press as the main shaping elements. However, these machines and their related processes present economic disadvantages because of additional expenses required to improve and manage forming tools. To overcome these drawbacks, reconfigurable machines, such as dedicated and flexible manufacturing systems, were used as alternatives; they possess high flexibility for accomplishing forming processes. Reconfigurable machines are designed around a particular family of manufactured outcomes, allowing for high system flexibility. In light of the latest developments in reconfigurable machine design, this study proposes a new sheet metal forming roller called the discrete multi disk roller (MDR) as an alternative to the traditional roller design. Unlike existing processes, the MDR minimises production costs associated with material loss and effectively decreases forming errors. Furthermore, it utilises multi-disk as reconfigurable rollers. The technique and applicable procedure of the MDR are described, and wavy sheets with different dimensions and shapes are formed to verify the applicability of the reconfigurable roller, a critical component in the forming process. Thirteen parts with different configuration profiles were produced using the proposed MDR machine.Al-Khwarizmi Engineering Journa
Product-service systems and supply chain circularity: a mixed methods investigation.
Get PDFThe circular economy (CE) aims to create economic and environmental benefits, by keeping products and materials at highest utility and value through long-lasting design, repair, reuse, refurbishment, and recycling. CE transformation results in a slowing, closing, and narrowing of resource loops, which is also termed supply chain circularity (SCC). Product-service systems (PSSs), in which manufacturers meet customer needs by providing services instead of selling products, are considered key business model innovations for increasing SCC. However, there is a lack of empirical evidence on whether PSSs actually contribute to SCC or whether they are a facade behind which linear ‘business-as-usual’ continues. This PhD thesis conducts a mixed methods investigation of the relationship between PSSs and SCC. It consists of three papers: 1) a systematic literature review (SLR) of 67 papers; 2) a quantitative survey of 206 machinery and equipment manufacturing firms in the United Kingdom (UK); 3) a multiple-case study of three manufacturing firms in Germany and the UK.
The findings show that: 1) result-oriented PSSs have the highest potential contribution to SCC, followed by use- and finally product-oriented PSSs; 2) use-oriented PSSs are limited in contributing to a slowing of resource loops through refurbishment; 3) PSSs’ contribution to SCC depends on enabling and inhibiting contextual factors, especially organisational ones. In sum, this PhD study argues that PSSs can only catalyse the transition from a linear to a CE if an enabling business context is established. The PhD makes three key contributions to theory and practice: 1) it provides empirical evidence that PSSs do not inherently contribute to a slowing of resource loops; 2) it develops an empirically validated framework of enablers and barriers, particularly organisational ones; 3) it extends the SCC concept, by developing survey items and offering a first attempt at theorising how the transition to SCC occurs during a manufacturer’s servitization process.PhD in Leadership and Managemen
The effect of corrosion inhibitor on X-65 steel weldment in high flow rate conditions
Get PDFThis study aims to determine the performance of a commercial corrosion inhibitor (mixture of ethanediol, 2-butoxy ethanol, and fatty acid amine) in inhibiting weldment corrosion. The inhibitor's effect on parent metals (PM), heat affected zone (HAZ), and weld metal (WM) has been investigated on the corrosion behaviour of X65-welded structures in brine solution (10 m/s) using submerged jet impingement (SJI) flow loops. The results show that inhibitors can reduce the corrosion rate by 10 times to 0.36 mm/y for WM. Linear polarization resistance and electrochemical impedance spectroscopy (EIS) show that the WM exhibited the highest corrosion rate.The authors gratefully acknowledge the Ministry of Energy and Mineral Resources, Indonesia, for funding this research (Grant number: 4122 K/69/MEM/2014 ).Case Studies in Chemical and Environmental Engineerin