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A Kriging approach to model updating for damage detection
Get PDFFor complex or large structures, the model updating process
can be long and tedious and numerical methods can be computationally
expensive. Hence, practitioners and researchers often resort to
meta-modelling techniques when large problems are met. Even so, traditional
methodologies, such as the Efficient Global Optimisation, can
be slow and give sub-optimal results. This work proposes a new methodology
for the model updating of numerical systems based on a novel
Kriging approach for the scope of damage detection and quantification.
The framework proposed is based on a global-local optimisation strategy
recently developed by the authors, the refined Efficient Global Optimisation,
herein used to tweak finite element models’ parameters to match
the modal data extracted from a numerical system by using the residuals
of the modified total modal assurance criterion. The main advantage to
existing direct optimisation and meta-modelling frameworks is the more
efficient use of computational e ort for higher dimensional problems,
which is verified with the use of a numerical system
Maize meal (posho) served at selected boarding schools in western Uganda is highly contaminated with aflatoxins
Get PDFSupplementary material is available online at: https://doi.org/10.6084/m9.figshare.24885081The study aimed to evaluate food handling practices and assess the maize-bean supply chain in selected boarding schools of western Uganda. Additionally, it sought to determine the extent of aflatoxin exposure in the maize-bean meal consumed by students within the age range of 5 to 24. A cross-sectional study was conducted in two districts of Bushenyi and Sheema to gather 95 samples (31 beans, 32 maize flour, and 32 cooked maize flour-posho). In addition, 262 individual interviews were conducted. The findings revealed that only 9.38% of the schools store food as per World Health Organisation standards. The majority of schools (57.9%) purchase maize flour and beans from any stockist with no contractual obligations (random supplier), and all the 32 schools base on visual parameters, especially white colour, and smell to rule out aflatoxin contamination. Maize flour stored on the ground registered significantly (P = 0.0018) higher levels (54.3 ± 10.1 μg/kg) of total aflatoxins than that stored on a raised platform (14.7 ± 2.6 μg/kg). Likewise, the supplier significantly influenced total aflatoxins levels (P = 0.0064), with higher levels (44.6 ± 8.0 μg/kg) detected in maize flour supplied by a random supplier than a pre-qualified one (14.7 ± 2.6 μg/kg). Given the low levels (1.3 to 2.8 μg/kg), which are far less than the Maximum Tolerated Limit (MTL) of 10 μg/kg, aflatoxins do not pose a significant problem in beans. Aflatoxins exposure in younger children (5-12 years) was higher (61.5 ng/kg bw/day) than in older ones (13-24 years; 41.5 ng/kg bw/day). Similarly, the risk of developing hepatocellular carcinoma was greater in younger children (1.84 cases per 100,000 people) compared to older ones (1.24 cases per 100,000 people). The findings underscore an urgent need to formulate guidelines for procurement, storage, and food handling in schools, alongside intensifying inspection programmes for food handling. Additionally, there is need to expand the research scope by incorporating a greater number of schools from varied geographical areas within Uganda, while rigorously monitoring the entirety of the food supply chain.World Mycotoxin Journa
Unsteady swirl distortion in a short intake under crosswind conditions
Get PDFIn crosswind operating conditions, an aero-engine intake can be affected by notable unsteady flow distortions at the fan face. These distortions are typically associated with the ingestion of the ground vortex as well as with flow separation within the intake and can have a detrimental effect on the intake performance and therefore on the operability of the downstream compression system. Measurements of the unsteady velocity field within a model-scale intake under crosswind conditions were conducted using Stereo Particle Image Velocimetry (S-PIV) to characterize the velocity field and hence the intake flow distortion across the Aerodynamic Interface Plane (AIP) inside the duct. The intake distortion metrics were calculated for three operating conditions at a fixed crosswind velocity and increasing Mass Flow Capture Ratio (MFCR). The conditions at which the flow separates depend on crosswind velocity, ground clearance, the design of the intake and the MFCR. Flow characteristics of both low MFCR diffusion-driven, and high MFCR shock-induced separation were identified. The circumferential extent and intensity of the swirl distortion were found to be highly dependent on the crosswind velocity and MFCR. The swirl distortion caused by the diffusion-driven separation is greater than that due to shock-induced separation. The diffusion-driven separation was found to affect a bigger position of the intake AIP with higher time-average and peak values. An intermittent separation, that was observed for one value of MFCR in the range investigated, was found to cause peak levels of distortion twice the time-averaged values. Localized high swirl levels at a radial position near the intake surface correspondent to the tip region of a notional fan were observed. These can be expected to be detrimental to the operating stability of the downstream compression system.AIAA SCITECH 2024 Foru
Evaluation of porcine decomposition and total body score (TBS) in a central European temperate forest
Get PDFThe total body score (TBS) is a visual scoring method to scale the succession of decomposition stages. It compares decomposition between cadavers, to connect it with external taphonomic factors and estimate the post-mortem interval. To study decomposition in various climatic environments, pigs are often used as human proxies. Currently, there is one TBS system by Keough et al. (J Forensic Sci. 2017;62:986) for surface-deposited domestic pigs, coming from South Africa. Our study aims to evaluate this method and analyze porcine decomposition in Central Europe to inform forensic research and casework. We conducted an experiment studying six 50 kg pig carcasses in a temperate Swiss forest. Three observers documented decomposition patterns and rated the decomposition stages from photographs based on the porcine TBS model by Keough et al. (J Forensic Sci. 2017;62:986). We documented discrepancies between the carcass decomposition of our specimens and those in the South African study, especially related to the high insect activity in our experiment. Furthermore, we noted factors complicating TBS scoring, including rainfall and scavengers. The agreement between TBS observers from photographs was in the highest agreement category apart from one “substantial agreement” category. Our study is the first in Europe to systematically test the Keough et al. (J Forensic Sci. 2017;62:986) method. The results evidence that regional adaptations are required to be applicable for other environments. We present a modified approach based on experimental observations in a Swiss temperate forest. The identification of regional decomposition patterns and drivers will inform future taphonomy research as well as forensic casework in comparable contexts in Central Europe.Journal of forensic science
Unraveling the characteristics of dissolved organic matter removed by aluminum species based on FT-ICR MS analysis
Get PDFGiven the complexity of dissolved organic matter (DOM) and its interactions with coagulant chemicals, the mechanisms of DOM removal by aluminum (Al) coagulants remains a significant unknown. In this study, six test waters containing DOM with molecular weight (MW, 10 kDa) and hydrophobicity (hydrophilic, transphilic and hydrophobic) were prepared and coagulated with Al0, Al13 and Al30. The molecular-level characteristics of DOM molecules that were removed or resistant to removal by Al species were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that at the molecular level, saturated and reduced tannins and lignin-like compounds containing abundant carboxyl groups exhibited higher coagulation efficiency. Unsaturated and oxidized lipids, protein-like, and carbohydrates compounds were relatively resistant to Al coagulation due to their higher polarity and lower content of carboxyl groups. Al13 removed molecules across a wider range of molecular weights than Al0 and Al30, thus the DOC removal efficiency of Al13 was the highest. This study furthers the understanding of interactions between Al species and DOM, and provides scientific insights on the operation of water treatment plants to improve control of DOM.Water Researc
Effect of a fan on the unsteady distortion of s-duct intakes
Get PDFA key requirement for the integration of the propulsion and air induction systems is the assessment of the response of the fan to incoming flow distortion. This is especially crucial for the development of novel aircraft configurations with highly embedded engines. The recent advances in non-intrusive laser-based flow diagnostics increased the experimental capability to measure unsteady flows in convoluted intakes with high resolution in time and space. In the pathway to full-scale intake-engine tests, this work introduces the capability to successfully acquire non-intrusive high resolution flow distortion measurements in close proximity to a high-speed rotating fan. This also quantifies the impact of the fan on the inherent flow distortion of S-duct intakes. The measurements demonstrate that although the effect of the fan on the flow distortion is limited, the rotating blades can cause a local increase of the maximum levels swirl intensity at the blade tip region. Further development work on the ducted fan simulator is needed to operate the fan in the representative range of transonic rotors.The SINATRA project leading to this publication has received funding from the Clean Sky 2 Joint Undertaking (JU) under grant agreement No 886521. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Clean Sky 2 JU members other than the Union.58th 3AF International Conference on Applied Aerodynamic
AI-based reconfigurable inspection system (RIS): comprehensive model and implementation in industry
Get PDF56th CIRP International Conference on Manufacturing Systems 2023Due to global competition and continuously changing customer demand, manufacturers nowadays face frequent and unpredictable market shifts. Introducing reconfigurability into contemporary manufacturing systems can enhance cost-effective and rapid responsiveness to these variations. A Reconfigurable Manufacturing System (RMS) can provide a tailored production process in response to changes in operating procedures or machine statuses. Just like any other manufacturing system, RMS requires effective and timely diagnosis as well as prognosis to function smoothly. A Reconfigurable Inspection System (RIS) is designed within an RMS for data-oriented detection of product quality with a minimum number of inspection units. Existing studies about reconfiguration, however, focus on production while disregarding inspection. Artificial Intelligence (AI) has the potential to significantly assist manufacturers over the next decade due to their heavy dependency on data. AI applications such as Machine learning (ML) and Deep Learning (DL) can aid in addressing issues such as tracking manufacturing failures back to specific phases in the manufacturing process by learning relevant data patterns. Thus, this paper aims to provide an overview of the current literature on RMS as well as ML/DL technologies that can be integrated into RIS to enhance performance. Subsequently, a comprehensive model of an AI-based RIS is proposed based on the experimental results derived from existing publications, and the retrofitting procedure of a case study is presented. However, the proposed model and the retrofitting procedure are not validated by experimental results or physical implementation.56th CIRP International Conference on Manufacturing Systems 2023Procedia CIR
Deterministic observability calculations for zero-dimensional models of lithium–sulfur batteries
Get PDFAmong the various energy storage technologies under development, the lithium‑sulfur (Li–S) battery has considerable promise due to its higher theoretical energy density, small environmental footprint, and low projected costs. One of the main challenges posed by Li–S is the need for a battery management system (BMS) that can accommodate the system's complex multi-step redox behaviours; conventional approaches for lithium-ion batteries do not transfer. Most existing approaches rely on equivalent circuit network models, but there is growing interest in ‘zero-dimensional’ electrochemical models which can potentially give insights into the relative polysulfide species concentrations present at any given time. To be useful for state estimation, a model must be ‘observable’: it must be possible to uniquely determine the internal state through observation of the system's behaviour over time. Previous studies have assessed observability using numerical methods, which is an approximation. This study derives an analytic expression for the observability criterion, which allows greater confidence in the results. The analytic observability criterion is then validated against a numerical comparator. A zero-dimensional model from the literature is translated into an ordinary differential equation (ODE) form to define the state variables matrix A, the output matrix C, and subsequently the observability matrix O. These are compared to simulated numerical equivalents. In addition, the sensitivity of the numerical process has been demonstrated. The results have the potential to offer greater confidence in conclusions around observability, which in turn gives greater confidence in the effects of any algorithms based on them.This work was funded by the European Commission under grant agreement 814471, and the Innovate UK under grant TS/R013780/1.Journal of Energy Storag
Sediment and phosphorus transport during flood events in a Mediterranean temporary river
Get PDFFlood events, whose number and intensity are predicted to increase in the Mediterranean region, are difficult to monitor. This causes the number of observations of suspended sediment and total phosphorus concentration (|SS| and |TP|, respectively) during their occurrence to be still scarce. Non-perennial or temporary water bodies, which react more promptly to rainfall events, represent ideal natural observatories. In this study, observations of streamflow, |SS| and |TP|, carried out during some flood events, in the Celone river basin, a temporary river located in south-eastern Italy, are presented. The research examined the correlations between flows, concentrations and loads of sediment and phosphorus and investigated factors that influence sediment and phosphorous dynamics in the river basin. The results show no relationship between the time of the year and the precipitation quantity of each event. The high coefficient of determination of the |SS|–|TP| correlations (R2 = 0.67 on average) proves the importance of soil erosive processes in the delivery of phosphorus to the river. More than 73% of the total suspended sediment load and 83% of total phosphorus load in the period 2010–2011 were transported during the 11 monitored events. In addition to the discharge, |SS| and |TP| also depend on numerous other factors related to land management, such as soil cover and fertilizations. The study, thanks to the improved understanding of the mechanisms governing sediment and phosphorus losses, represents a useful contribution for river basin authorities who have to draw up management plans aimed at preventing eutrophication phenomena and soil fertility reduction.European Community's Seventh Framework Programme, FP7/2007–2011, through the MIRAGE Project (Contract n. 211732).Environmental Earth Science
From carbon-neutral to climate-neutral supply chains: a multidisciplinary review and research agenda
Get PDFPurpose:
We conduct a multidisciplinary systematic literature review on climate neutrality in the supply chain. While carbon neutrality has gained prominence, our study argues that achieving carbon neutrality alone is not enough to address climate change effectively, as non-CO2 greenhouse gases (GHG) are potent contributors to global warming.
Design/methodology/approach:
We used multiple databases, including EBSCO, ProQuest, Science Direct, Emerald and Google Scholar, to identify articles related to climate neutrality in the context of non-CO2 gases. A total of 71 articles in environmental science, climate change, energy systems, agriculture and logistics are reviewed to provide insights into the climate neutrality of supply chains.
Findings:
We find that, in addition to CO2, other GHG such as methane, nitrous oxide, ozone and fluorinated gases also significantly contribute to climate change. Our literature review identified several key pillars for achieving net-zero GHG emissions, including end-use efficiency and electrification, clean electricity supply, clean fuel supply, “GHG capture, storage and utilization,” enhanced land sinks, reduced non-CO2 emissions and improved feed and manure management.
Originality/value:
We contribute to the literature on climate neutrality of supply chains by emphasizing the significance of non-CO2 GHG along with CO2 and highlighting the need for a comprehensive approach to climate neutrality in addressing climate change. This study advances the understanding of climate neutrality of supply chains and contributes to the discourse on effective climate change mitigation strategies. It provides clear future research directions