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Alternate inks for arbuscular mycorrhizal root staining
Get PDFAlternate methods for root staining of arbuscular mycorrhizal (AM) fungi have recently gained more attention for the reduction of hazard exposure to the user. Sheaffer® blue ink has been employed for such an identification and quantification, having shown and increased degree of image clarity. However, sourcing Sheaffer® blue ink is becoming problematic, leading to the need to find alternative inks that are readily available. Parker® ink is a well-known brand, providing comparable colour option to Sheaffer®. Two Parker® inks, blue and washable blue, were employed alongside Sheaffer® blue for comparative AM fungal root staining. From quantified AM fungal vesicles and arbuscles, along with the degree of stained image clarity under microscopy, none of the inks utilised for this comparison produce a significantly (P=0.97) different AM fungal quantification or change in image clarity. Therefore, results of the present communication suggest that Parker® blue and washable blue inks are alternative ink stains for the viewing and quantification of AM fungi in host cortical root tissues.Access Microbiolog
Benefits realisation: case studies in public major project delivery with recommendations for practice
Get PDFPublic projects are enablers of policy and are often framed within a political context characterized by the unpredictable, emergent, ambiguous and contextual; this creates tensions around conceptualizations of project performance and project success. Public projects are generally authorized based on a favourable benefit-to-cost ratio, so ex-post scrutiny of realized benefits is crucial to effective evaluation. Nevertheless, evidence suggests that sometimes, the focus on project delivery may come at the expense of benefits realization. This paper describes part of a wider programme of research into benefits realization in public projects. We present ‘deep dives’ into 3 UK projects and draw on a formal theoretical base to consider questions such as ‘what is a benefit?’, ‘how good are we at defining benefits/beneficiaries?’, ’how can we manage and capture evolving benefits in complex environments?’; ‘how do we recognize and accept complexity while the environment changes?’ and ‘what effects does this have on our understanding of benefits realization?’. This paper presents an analysis of the case studies and provides a synthesis of the main findings. We make eight recommendations for professional practice in the field of benefits management and set out some conclusions relevant to the wider discourse on the evaluation of investment in public projects.The researchers gratefully acknowledge the financial support of the Project Management Institute (PMI) and the Project X #BetterGovProjects research community for their ongoing support
Effect of solutionizing and double ageing treatments on the microstructural characteristics and tensile properties of Inconel 718 welds
Get PDFInconel 718 joints were fabricated using the pulsating direct current gas tungsten arc welding (PDCGTAW) and laser-arc hybrid welding (LAHW) techniques using Ni-Cr-Mo-rich filler. A cyclic post-weld heat treatment (PWHT) comprising 980°C/20 min./air cooling; followed by two-stage ageing 720°C/8 h/furnace cooling and 620°C/8 h/air cooling was performed on both joints. The liquation cracking was noticed on the heat-affected zone (HAZ) of the LAHW joints. Microstructural characteristics were assessed on the joints in both as-welded (ASW) and PWHT conditions. Regardless of the joints, the coarse Mo-rich segregates were noticed in the fusion zone (FZ) in the ASW conditions. On the contrary, the partial dissolution of MC, precipitation of δ-Ni3Nb needles and the coarsening of strengthening precipitates were observed on LAHW and PDCGTAW joints after subjecting to cyclic PWHT respectively. Tensile studies corroborated that there is a considerable enhancement in the tensile and 0.2% offset yield strengths of LAHW joints after being exposed to PWHT, despite the formation of HAZ liquation cracking.Royal Academy of Engineering: DIA-2021-144Journal of Materials Research and Technolog
Advancing social procurement: an institutional work perspective
Get PDFPurpose:
The adoption of social procurement, the emerging practice of using a firm's spending power to generate social value, requires buying firms to navigate conflicts of institutional logics. Adopting an institutional work perspective, this study aims to investigate how buying firms change their existing procurement institutions to adopt and advance social procurement.
Design/methodology/approach:
The authors conducted an in-depth case study of a social procurement initiative in the UK. This case study comprised of 16 buying firms that were actively participating in the social procurement initiative at the time of data collection (2020–2021). The data were largely captured through a set of 41 semi-structured interviews.
Findings:
Four types of institutional work were observed: reducing institutional conflicts, crossing institutional boundaries, legitimising institutional change and spreading the new institutional logic. These different types of institutional work appeared in a sequential way.
Originality/value:
This study contributes to various strands of literature investigating the role of procurement in generating value and benefits within societies, adopting an institutional lens to investigate the buying firms' purposeful actions to change procurement institutions. Secondly, this study complements the existing literature investigating the conflicts of institutional logics by illustrating the ways firms address such institutional conflicts when adopting and advancing social procurement. Finally, this work contributes to the recently emerging research on institutional work that examines the creation and establishment of new institutions by considering the existing procurement institutions in the examination of institutional work
Keypoints-based heterogeneous graph convolutional networks for construction
Get PDFArtificial intelligence algorithms employed for classifying excavator-related activities predominantly rely on sensors embedded within individual machinery or computer vision (CV) techniques encompassing a large scene. The existing CV-based methods are often difficult to tackle an image including multiple excavators and other cooperating machinery. This study presents a novel framework tailored to the classification of excavator activities, accounting for both the excavator itself and the dumpers collaborating with the excavator during operations. Distinct from most existing related studies, this method centres on the transformed heterogeneous graph data constructed using the keypoints of all cooperating machinery extracted from an image. The resulting model leverages the relationships between the mechanical components of an excavator in varying activation states and the associations between the excavator and the collaborating machinery. The framework commences with a novel definition of keypoints representing different machinery relevant to the targetted activities. A customised Machinery Keypoint R-CNN method is then developed to extract these keypoints, forming the basis of graph notes. By considering the type, attribute and edge of nodes, a Heterogeneous Graph Convolutional Network is finally utilised for activity recognition. The results suggest that the proposed framework can effectively predict earthwork activities (with an accuracy of up to 97.5%) when the image encompasses multiple excavators and cooperating machinery. This solution holds promising potential for the automated measurement and management of earthwork productivity within the construction industry. Code and data are available at: https://github.com/gillesflash/Keypoints-Based-Heterogeneous-Graph-Convolutional-Networks.git.Royal Academy of Engineering Industrial Fellowship: IF2223B-110Expert Systems with Application
Propulsion aerodynamics for a novel high-speed exhaust system
Get PDFA key requirement to achieve sustainable high-speed flight and efficiency improvements in space access, lies in the advanced performance of future propulsive architectures. Such concepts often feature high-speed nozzles, similar to rocket engines, but employ different configurations tailored to their mission. Additionally, they exhibit complex interaction phenomena between high-speed and separated flow regions at the base, which are yet not well understood, but are critical in terms of pressure and viscous forces. This paper presents a numerical investigation on the aerodynamic performance of a representative novel exhaust system, which employs a high-speed, truncated, ideal contoured nozzle and a complex-shaped cavity region at the base. Reynolds-Averaged Navier-Stokes computations are performed for a number of Nozzle Pressure Ratios (NPRs) and free stream Mach numbers in the range of 2.7 < NPR < 24 and 0.7 < M∞ < 1.2 respectively. The corresponding Reynolds number lies within the range of 1.06 · 106 < Red < 1.28 · 106 based on the maximum diameter of the configuration. A decomposition of the drag domain forces exposes the major trends between the constituent elements. The impact of the cavity on the aerodynamic characteristics of the apparatus is revealed by direct comparison to an identical non-cavity configuration. Results show a consistent trend of increasing base drag with increasing NPR for all examined M∞ for both configurations. This is attributed to the jet entrainment effect and to the lower base pressure imposed by the higher jet flow expansion. The cavity region is found to have almost no impact on the incipient separation location of the nozzle flow. At low supersonic speeds of M∞ = 1.2 and high NPRs, the cavity has a significant effect on the aerodynamic performance, transitioning nozzle operation to under-expanded conditions. This results in approximately 12% higher drag coefficient compared to the non-cavity case and shifts the minimum NPR for which the system produces positive gross propulsive force to higher values.Reaction Engines Ltd.
Cranfield Air and Space Propulsion Institute (CASPI)ASME Turbo Expo 2023: Turbomachinery Technical Conference and Expositio
Efficient reduced-order thermal modelling of scanning laser melting for additive manufacturing
Get PDFAdditive manufacturing (AM) with a scanning laser (SL) to independently control melt pool shape has the potential to achieve part building with high geometric accuracy and complexity. An innovative dynamic convection boundary (DCB) method is proposed to develop a reduced-order finite element (FE) model to accelerate the thermal analysis of a SL process for AM. The DCB method approximates the thermal conduction of the adjacent material around the bead region by using a convection boundary condition that can be dynamically adjusted during the numerical solution. Thereby, a smaller problem domain and fewer elements are involved in the reduced-order FE modelling. A non-oscillating equivalent bar-shaped heat source was also introduced as a simplified substitution for a high oscillation frequency SL heat source. The DCB-based reduced-order thermal model achieved over 99% accuracy compared to the full-scale model but reduced the element amount by 73% and the computational time by 58%. The use of the bar-shaped equivalent heat source can further enhance computational efficiency without compromising the prediction accuracy of a high oscillation frequency SL process. The DCB-based reduced-order thermal modelling method and equivalent heat source could be adopted to boost extensive parametric analysis and optimisation for novel AM processes. Study on large structures AM could also be facilitated by simplifying the computation at critical regions. This study can also enable efficient thermal analyses of different manufacturing processes, such as welding, cladding, and marking.Engineering and Physical Sciences Research Council (EPSRC): EP/R027218/1Journal of Materials Processing Technolog
Automated prediction of crack propagation using H2O AutoML
Get PDFCrack propagation is a critical phenomenon in materials science and engineering, significantly impacting structural integrity, reliability, and safety across various applications. The accurate prediction of crack propagation behavior is paramount for ensuring the performance and durability of engineering components, as extensively explored in prior research. Nevertheless, there is a pressing demand for automated models capable of efficiently and precisely forecasting crack propagation. In this study, we address this need by developing a machine learning-based automated model using the powerful H2O library. This model aims to accurately predict crack propagation behavior in various materials by analyzing intricate crack patterns and delivering reliable predictions. To achieve this, we employed a comprehensive dataset derived from measured instances of crack propagation in Acrylonitrile Butadiene Styrene (ABS) specimens. Rigorous evaluation metrics, including Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and R-squared (R2) values, were applied to assess the model’s predictive accuracy. Cross-validation techniques were utilized to ensure its robustness and generalizability across diverse datasets. Our results underscore the automated model’s remarkable accuracy and reliability in predicting crack propagation. This study not only highlights the immense potential of the H2O library as a valuable tool for structural health monitoring but also advocates for the broader adoption of Automated Machine Learning (AutoML) solutions in engineering applications. In addition to presenting these findings, we define H2O as a powerful machine learning library and AutoML as Automated Machine Learning to ensure clarity and understanding for readers unfamiliar with these terms. This research not only demonstrates the significance of AutoML in future-proofing our approach to structural integrity and safety but also emphasizes the need for comprehensive reporting and understanding in scientific discourse.Sensor
Managing assumption-driven design change via margin allocation and trade-offs
Get PDFAssumptions are commonly introduced to fill gaps in knowledge during the engineering design process. However, the uncertainty inherent in these assumptions constitutes a risk that ought to be mitigated. That is, assumptions can negatively impact the system if they turn out to be invalid. Adverse effects may include system failure, violation of requirements, or budget and schedule overruns. In this paper, the relationships between assumptions and margins are made explicit, with the purpose of aiding risk mitigation, as well as accommodating future opportunities such as product evolvability. To this end, a novel assumption management framework is proposed, which consists of a taxonomy of margins, an algorithm for change absorber localisation, and an interactive approach for margin trade-off. The proposed framework is demonstrated with a conceptual aircraft design use case, which shows that the most relevant margins can be identified, given a revision of a set of assumptions. It is also demonstrated that the application of the method allowed the margins to be adjusted according to the confidence in the assumptions, while maintaining satisfaction of all design constraints, without unacceptable compromise of system performance.Journal of Engineering Desig
Coupled analysis between catenary mooring and VLFS with structural hydroelasticity in waves
Get PDFThe rapid growth of marine renewables has led to the development of very large floating structures (VLFS) that are designed to operate in deep seas. It is significant to understand the mechanism of the coupled effects between deformable VLFS and catenary mooring system. This paper presents a time-domain hydro-elastic-moored model developed by integrating a quasi-static mooring module into a fully coupled Computational Fluid Dynamics (CFD) - discrete-module-beam (DMB) approach. The model is used to investigate the coupled effects between structural hydroelasticity and loose-type mooring systems on a deformable VLFS in waves. The mooring and hydroelasticity codes are validated separately and show favourable agreement with other numerical and experimental results. Then the coupled effects between the mooring system and structural hydroelasticity are evaluated by assigning various design parameters, i.e., VLFS structural stiffness and mooring stiffness. The numerical results, including dynamic motions, longitudinal vertical bending moments (VBMs) and mooring tension forces are presented and analysed. These results can be used to design a VLFS with mooring in medium-deep sea, and help with the conventional mooring design for a less-stiffness VLFS due to hydroelastic response.Marine Structure