University of Strathclyde
  • Glasgow, United Kingdom
Recent publications
Asset inspection of large structures such as storage tanks in the oil, gas and petrochemical industry is a challenging and time-consuming process. Compared to the state-of-the-art inspection methods of these structures using ultrasonic bulk wave phased array techniques, guided waves provide a mechanism for monitoring inaccessible areas and increasing the testing range to speed up the inspection process. Combining these two approaches, an efficient inspection scheme can be achieved. For this purpose, in this work, the possibility of exciting a single higher order guided wave mode at a low dispersion region is examined, using a conventional linear phased array on a 10 mm thick sample. An analytical model based on modal analysis is derived. Then, the time delays across each element of the array are optimally selected and a necessary condition on the pitch is provided, to enhance the purity of the desired mode. The results are promising, illustrating that single mode excitation is possible at high frequency-thickness products, greater or equal than 15 MHz·mm. Furthermore, the phased array transducer allows for dynamic mode selection capabilities; that is, feeding the appropriate excitation signals on each channel, different modes can be excited, without having to physically alter the transducer configuration.
Background: Gay, bisexual and other men who have sex with men (GBMSM) are at far greater risk of experiencing poor mental health (MH) than wider society. This disparity was exacerbated by additional 'unique to sexual minority status' COVID-19 stressors. Objective: This sequential, mixed-methods study examined remote MH help-seeking among GBMSM in the U.K. and Ireland during the first COVID-19 lockdown. Methods and Results: Quantitative survey data (n = 1368), analysed with logistic regression, suggested GBMSM experiencing moderate-to-severe anxiety and those with a past MH diagnosis were most likely to seek MH support. Thematic analysis of qualitative interview (n = 18) data identified multiple barriers and enablers to GBMSM seeking remote MH help, with the help primarily sought from GBMSM-facing organisations and generic online resources. Finally, the behaviour change wheel was used to generate theoretically informed recommendations to promote MH help-seeking among GBMSM in Scotland. Implications: We discuss how applying these recommendations in the short, medium and long term will begin to address GBMSM's MH needs, post COVID-19.
Techniques for learning vectorial representations of graphs ( graph embeddings ) have recently emerged as an effective approach to facilitate machine learning on graphs. Some of the most popular methods involve sophisticated features such as graph kernels or convolutional networks. In this work, we introduce two straightforward supervised learning algorithms based on small-size graphlet counts, combined with a dimension reduction step. The first relies on a classic feature extraction method powered by principal component analysis (PCA). The second is a feature selection procedure also based on PCA. Despite their conceptual simplicity, these embeddings are arguably more meaningful than some popular alternatives and at the same time are competitive with state-of-the-art methods. We illustrate this second point on a downstream classification task. We then use our algorithms in a novel setting, namely to conduct an analysis of author relationships in Wikipedia articles, for which we present an original dataset. Finally, we provide empirical evidence suggesting that our methods could also be adapted to unsupervised learning algorithms.
Fibular response to disuse has been described in cross-sectional but not longitudinal studies. This study assessed fibular bone changes in people with spinal cord injury. Fibular bone loss was less than in the tibia and was not correlated together. This might explain low fibular fracture incidents in these patients. Purpose: Cross-sectional studies suggest that the fibula responds differently to loading and disuse compared to the tibia. Whilst tibial bone changes following spinal cord injury (SCI) have been established in longitudinal studies, fibular changes remain unexplored. Methods: Fibular and tibial bone parameters were assessed in 13 individuals with SCI (aged 16-76 years). Peripheral quantitative computed tomography scans were acquired at 4%, 38% and 66% distal-proximal tibia length at 5 weeks and 12 months post-injury. Changes in 4% site total bone mineral content (BMC), total cross-sectional area (CSA) and bone mineral density (BMD), and 38% and 66% sites total BMC, total CSA, cortical BMD and cortical CSA were assessed using paired T-tests. Relationships between bone loss in the two bones at equivalent sites were assessed using paired T-tests and correlation. Results: At the 4% site, fibular total BMC and BMD losses were less than tibial losses (- 6.9 ± 5.1% and - 6.6 ± 6.0% vs - 14.8 ± 12.4% and - 14.4 ± 12.4%, p = 0.02 and p = 0.03, respectively). Similarly, at the 66% site, fibular BMC losses were less than those in the tibia (- 2.0 ± 2.6% vs - 4.3 ± 3.6%, p = 0.03), but there was no difference at 38% (- 1.8 ± 3.5% vs - 3.8 ± 2.1%, p = 0.1). No correlation was observed for BMC changes between the two bones (all p > 0.25). Conclusion: These results support cross-sectional evidence of smaller disuse-related bone loss in the fibula compared to the tibia. These results may in part explain lower incidence of fibula fractures in individuals with chronic SCI. The lack of association between losses in the two bones might point to different underlying mechanisms.
Background Needle visualisation during ultrasound-guided procedures is a skill that can be difficult to practise, with commercially available phantoms being expensive and often unrealistic. Our aim was to find an inexpensive, reproducible model that could be used to assist in developing this skill. Methods Pork shoulder, beef brisket, and lamb shoulder joints were compared to a standard blue ultrasound phantom. Five ‘chunky’ yarn pieces were twisted together and threaded through each joint to simulate hyperechoic nerves. Participants were instructed to ultrasound each specimen and insert a needle close to a nerve like structure. Using a visual analogue scale, specimens were scored based on realism of appearances of ultrasound images and ‘feel’ of needling. Results 38 people participated. All specimens of meat scored significantly higher than the blue phantom ( p = 0.01). There was no significant difference between the different types of meat. Conclusions Pork, beef and lamb joints are an effective model to use for simulation training for needling skills. They have limited lifespan, but due to its relatively low cost, it is feasible to discard the meat after each training workshop. We hope the use of inexpensive meat products will make ultrasound simulation training simpler to organise and more effective.
This paper presents a comparative assessment of four low voltage fault ride through (LVFRT) techniques that alleviate the effects of power imbalance during AC network faults for voltage source converter (VSC)-based wind energy conversion systems (WECSs). The techniques appraised include a software-based coordinated control (CC) technique, commercially available dumping resistor (DR) technique, and two energy storage techniques, namely, superconductive magnetic energy storage (SMES) and supercapacitor energy storage (SCES). The techniques presented are technically viable solutions for alleviating impacts of AC network faults on the WECS. The techniques have previously been assessed by performance-based metrics, whereas this paper aims to form a more comprehensive assessment by expanding the scope from the performance-based comparison to include economic considerations and practical limitations. Based on qualitative review of technically viable designs, this study presents quantitative substantiation with time-domain simulations of symmetrical and asymmetrical AC network faults. The comparative assessment is formulated based on assessing key performance metrics including grid code compliance, electrical and mechanical stress reduction, LVFRT response speed, hardware implementation, system efficiency and investment reduction. The assessment findings suggest that a performance-based study fails to highlight the potential financial and practical barriers that may exist regarding the implementation of the LVFRT solutions especially with energy storage-based techniques. However, the flexibility, benefits and increasing feasibility regarding energy storage systems may make them a preferred option for LVFRT of critical WECSs.
Needle biopsy is an essential part of modern clinical medicine. The puncture accuracy and sampling success rate of puncture surgery can be effectively improved through virtual surgery. There are few three-dimensional puncture (3D) models, which have little significance for surgical guidance under complicated conditions and restrict the development of virtual surgery. In this paper, a 3D simulation of the muscle tissue puncture process is studied. Firstly, the mechanical properties of muscle tissue are measured. The Mooney-Rivlin (M-R) model is selected by considering the fitting accuracy and calculation speed. Subsequently, an accurate 3D dynamic puncture model is established. The failure criterion is used to define the breaking characteristics of the muscle, and the bilinear cohesion model defines the breaking process. Experiments with different puncture speeds are carried out through the built in vitro puncture platform. The experimental results are compared with the simulation results. The experimental and simulated reaction force curves are highly consistent, which verifies the accuracy of the model. Finally, the model under different parameters is studied. The simulation results of varying puncture depths and puncture speeds are analyzed. The 3D puncture model can provide more accurate model support for virtual surgery and help improve the success rate of puncture surgery.
Cross-border mergers and acquisitions (M&As) are highly emotional events for the employees of involved organizations. The strength and directionality of emotional reactions can result in positive or negative employee outcomes contributing to success or failure of cross-border M&As. Existing studies on emotions and cross-border M&As have identified various underlying mechanisms and factors that influence employee emotions in cross-border M&A activities, leading to a fragmentation of current research on this topic. In this article, we systematically review the interdisciplinary literature on the role played by emotions in cross-border M&As by analyzing a sample of 78 articles published between 2000 and 2021. We contribute to the current literature by (1) providing a holistic and deeper understanding of the role played by emotions in cross-border M&As; (2) mapping the current state of the interdisciplinary literature on emotions and cross-border M&As; and (3) developing a multi-level framework, and identifying key theories and emerging themes to be examined in future studies.
Background Movement behaviours are important for infant (0–12 mo) and toddler (1–2 yrs) health and development, yet very little is known about adherence to the 24-hour movement behaviour guidelines and parents perception of these behaviours in these age groups. This study aimed to examine parental perceptions of movement behaviours and adherence to guidelines in a sample of UK parents with children 0–18 months. Methods Participants were 216 parent-child dyads from the cross-sectional Movement Behaviour Assessment in Infants and Toddlers (M-BAIT) study. Tummy time, screen time, restraint time and sleep were measured using a parental questionnaire. A sub-sample of parents were asked about their priority areas for their child’s health and development. Frequencies were used to describe the proportion of children meeting movement behaviour guidelines, the number of guidelines met and priority areas for parents. Mann-Whitney U-tests (continuous variables) and chi-square tests (categorical variables) were used to assess the differences between boys and girls. Results For those under 12 months of age, just over 30% of children met tummy time recommendations, 41.3% met the screen time guidelines, 57.8% met restraint guidelines and 76.2% met sleep guidelines. For those 12 months and over, 24.1% met the screen time guidelines, 56.9% met restraint guidelines and 82.8% met sleep guidelines. Parents identified sleep and physical activity as top priorities for their child. Limiting screen time was deemed least important. Conclusion In this sample of UK infants and toddlers (0–18 months), few adhered to the sedentary behaviour and tummy time guidelines, whereas the majority meet sleep guidelines. This mirrors parental priorities; limiting screen time was seen as less important, with sleep and physical activity deemed most important. These findings suggest greater efforts are needed to raise awareness about screen and tummy time, supporting parents and care-providers to promote positive movement behaviours.
One of the key challenges of uncertainty analysis in model updating is the lack of experimental data. The definition of an appropriate uncertainty quantification metric, which is capable of measuring as sufficient as possible information from the limited and sparse experimental data, is significant for the outcome of model updating. This work is dedicated to the definition and investigation of a general-purpose uncertainty quantification metric based on the sub-interval similarity. The discrepancy between the model prediction and the experimental observation is measured in the form of intervals, instead of the common probabilistic distributions which require elaborate experimental data. An exhaustive definition of the similarity between intervals under different overlapping cases is proposed in this work. A sub-interval strategy is developed to compare the similarity considering not only the range of the intervals, but more importantly, the distributed positions of the available observation samples within the intervals. This sub-interval similarity metric is developed to be capable of different model updating frameworks, e.g. the stochastic Bayesian updating and the interval model updating. A simulated example employing the widely known 3-dof mass-spring system is presented to perform both stochastic Bayesian updating and interval updating, to demonstrate the universality of the proposed sub-interval similarity metric. A practical experimental example is followed to demonstrate the feasibility of the proposed metric in practical application cases.
Superhydrophobic surfaces have attracted extensive attention over the past decade, primarily due to their self-cleaning, corrosion resistance and anti-bacterial abilities. However, it is still a challenge to prepare superhydrophobic surfaces with good chemical stability, low cost, environmental friendliness, and suitable for large-scale production applications. In this paper, a hybrid laser-chemical method to prepare superhydrophobic micro-patterns on 316L stainless steel were put forward, which combined laser ablation and laser assisted chemical decomposition of stearic acid (C17H35COOH). Experiments show that under the laser power of 10 W, the frequency of 150 kHz, the speed of 20 mm/s, and the mesh spacing of 75 μm, the best superhydrophobicity with a static contact angle of 153.9° can be obtained. The fundamental mechanism of laser-chemical method is the increase of the non-polar CC(H) bond of specimen by laser assisted hydrodeoxygenation reaction of stearic acid. Moreover, unlike laser ablation-stearic acid coated specimen, the specimen prepared by laser-chemical method can maintain superhydrophobicity after 10 min of ultrasonic cleaning. The electrochemical corrosion experiments shows that the hybrid laser-chemical method can manufacture superhydrophobic specimens with better chemical durability and corrosion resistance.
New wind turbine technologies and designs are being explored in order to reduce the cost of energy from offshore wind farms. Two potential routes to a lower cost of energy are the X- Rotor Concept (XRC) and Multi-Rotor System (MRS) turbines. A key cost saving for both Novel concepts included in this paper is operation and maintenance (O&M) costs savings. The major component replacement cost for conventional horizontal axis, XRC and MRS turbines are examined and the benefits of the concepts are provided in this paper. A review on existing decision support systems for offshore wind farm O&M planning is presented with a focus on how applicable these previous models are to novel turbine concepts, along with analysis of how the influential factors can be modified to effectively model XRC and MRS.
The rapid growth of renewable energy developments, particularly offshore wind, means that worldwide there are hundreds of artificial structures in the marine environment that will at some point require removal. Decommissioning activities can have a range of effects on the environment, which are assessed through an Environmental Impact Assessment (EIA) prior to removal. EIA provides an opportunity to explore the best environmental options for decommissioning if utilised early in the planning process during the wind farm design. EIA should be utilised as a decision-aiding tool to assess impacts and design mitigation and monitoring across the life of an asset. In this paper, potential environmental impacts, mitigation measures, and alternative actions are explored as examples of best environmental practice-based thinking at a range of scales and for multiple receptors. The removal of structures might be challenging with regards to best environmental options if countries require changes to policy. We pose alternative actions to be considered in EIA which take circular economy into account and maximise environmental benefit in the long term. To enable the best environmental outcomes, we propose that EIA should be used proactively and reflectively with a tailored approach to designing decommissioning.
The UK Government and British industries are making important efforts for the development and implementation of carbon capture, transport and storage (CCTS). Critical to this will be an understanding of the composition and characteristics of the industrial clusters and of the costs for the CCTS systems. However, the available literature presents a wide range of cost values and many of the studies do not tend to consider all of the carbon transport and storage elements together. Moreover, there are a very limited number of UK specific analyses and in some cases the studies are considered to be too historical. In this paper, we present a review and characterisation of the main UK industrial clusters, in terms of geographical limits, available infrastructure, industries present and level of emissions. We then provide a brief review of carbon transport and storage (T&S) cost models and costing information before conducting a techno-economic assessment of the potential T&S system costs for the UK industrial clusters. To the best of our knowledge, this integrated analysis has not been conducted for the UK context, and this is key for policy development and to assess the wider economic impacts of CCTS. From our cluster characterisation and techno-economic analysis, we found that there is important potential for CCTS for industrial decarbonisation in the UK. Also, the creation of a CO2 shipping industry will allow for industrial clusters that do not have an adequate storage sites nearby to use the CCTS infrastructure in other sites. The development of a CO2 shipping infrastructure also enables carbon management and storage services to be exported to polluters overseas, potentially creating and maintaining jobs and economic growth. We believe that the cluster characterisation and cost estimates produced here provide valuable insight to inform policy and can be used as a first step for to develop further analysis in policy relevant areas such as an analysis of the wider economic impacts of these investments, the effect on jobs and competitiveness and the impact on the wider society.
This paper presents a framework for evaluating the quality of enhancement of positive impacts in Environmental Impact Assessment reports (EIARs). The ‘Enhancement Quality Testing Framework’ created for this study is structured around four performance indicators to evaluate enhancement measures detailed in EIARs that focus on: Inclusion; Timing; Thoroughness; and Responsibility & Monitoring. In this way a holistic view of enhancement has been taken to create a framework to evaluate enhancement quality. The framework was tested in documentary research of 24 Scottish EIARs published between 2015 and 2020 (including relevant documents submitted as part of the planning application, such as Environmental Management Plans). The results highlighted a wide recognition of enhancement (70%) among the EIAR evaluated. However, the majority of grades assigned across the performance indicators for the reports examined fell within ‘Deficient’ or ‘Not Present’. The framework could be used and adapted by developers, consultants, decision makers and academics to provide insight, and to introduce accountability, regarding the quality of enhancement integration in EIA practice.
Potentially toxic elements (PTEs), persistent organic pollutants, and emerging contaminants make sewage sludge management challenging. There is significant interest in thermal treatment technologies that can destroy these compounds. The most common thermal treatment, incineration, poses risks due to formation and/or release of hazardous substances in process emissions such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and PTEs. Smouldering has been introduced recently as a potential treatment for managing sewage sludge. Smouldering systems present several advantages over traditional incinerators; however, there are still uncertainties regarding process by-products. This key question was investigated in three laboratory-scale tests (0.08 m radius) and five oil drum-scale tests (0.3 m radius) that were evaluated for PCDD/Fs and PTEs in the mixture before and after treatment as well as in process emissions. Volatile organic compounds (VOCs) were also measured. These experiments represent a broad spectrum of conditions to evaluate process emissions, from robust self-sustaining to extinction of smouldering. Robust smouldering had negligible PCDD/Fs in process emissions. Weak smouldering had low levels of PCDD/Fs (emissions factor: 3.3 ± 0.3 μg TEQ/Mg dried sludge destroyed), levels less than uncontrolled emissions from commercial incinerators. Overall, smouldering acted as a sink for PCDD/Fs, as only 0–3% of the PCDD/Fs originally present in the sludge were released in the emissions, and >99% of the remainder were destroyed with <1% remaining in post-treatment ash. No evidence was found to support de novo synthesis or precursor reactions forming new PCDD/Fs. In addition, 94–100% of all the PTEs analyzed were retained in the post-smouldered material. These results indicate that only minimal emissions treatment for PTEs, PCDD/Fs, and VOCs may be necessary for future sewage sludge smouldering systems. These low emissions risks combined with its unique ability to handle high moisture content waste, indicate that smouldering has significant potential as a valuable waste management technique.
This paper considers a class of hybrid stochastic differential equations (SDEs) with different structures in different modes. In some modes, the coefficients of the SDEs satisfy the linear growth condition, while in the other modes, the coefficients are highly nonlinear. These systems are often unstable. This paper aims to design a discrete-time feedback control which is only put in a part of modes where the coefficients are highly nonlinear, such that these systems become stable. The stabilities concerned include H∞-stability and exponential stability in the moment, as well as almost sure stability. Finally, an example is given to illustrate these results.
Energy poverty still affects more than 37 million people in Europe. Due to the COVID-19 crisis, this number may increase significantly. However, efforts to tackle this complex problem have thus far proved insufficient. The intersection of domains from different disciplines is increasingly relevant within energy social science. Social entrepreneurship has a mission to alleviate social problems. Thus, the role of social entrepreneurship and social innovation in tackling energy poverty, although still an emerging area of research, is receiving increasing attention. With an aim to contribute to assessing the state of the research on this topic, a systematic literature review was developed on the intersection between energy poverty, social innovation, and social entrepreneurship in countries in the Global North. The results of the review show the central dimensions of social entrepreneurship and social innovation outlined by researchers, such as the collective and network nature of social entrepreneurship, hybrid skills, proximity, involvement of households, and a user-centred approach, shedding light on the primary potentialities of interventions in energy poverty driven by the social entrepreneurship phenomenon. Such findings may help social entrepreneurs and innovators, as well as policymakers, recognise possibilities and challenges in the field. Based on the outcomes of this review, potential new avenues for research within the intersection of the three domains are identified.
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19,671 members
Maurizio Collu
  • Naval Architecture, Ocean and Marine Engineering
Luis M Bimbo
  • Strathclyde Institute of Pharmacy and Biomedical Sciences
Margaret Stack
  • Department of Mechanical and Aerospace Engineering
Damion Corrigan
  • Department of Pure and Applied Chemistry
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