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Empirical modeling of stress concentration factors using artificial neural networks for fatigue design of tubular T-joint under in-plane and out-of-Plane bending moments
No full textPurpose
Stress concentration factors (SCFs) are commonly used to assess the fatigue life of tubular T-joints in offshore structures. SCFs are usually estimated from parametric equations derived from experimental data and finite element analysis (FEA). However, these equations provide the SCF at the crown and saddle points of tubular T-joints only, while peak SCF might occur anywhere along the brace. Using the SCF at the crown and saddle can lead to inaccurate hotspot stress and fatigue life estimates. There are no equations available for calculating the SCF along the T-joint's brace axis under in-plane and out-of-plane bending moments.
Design/methodology/approach
In this work, parametric equations for estimating SCFs are developed based on the training weights and biases of an artificial neural network (ANN), as ANNs are capable of representing complex correlations. 1,250 finite element simulations for tubular T-joints with varying dimensions subjected to in-plane bending moments and out-of-plane bending moments were conducted to obtain the corresponding SCFs for training the ANN.
Findings
The ANN was subsequently used to obtain equations to calculate the SCFs based on dimensionless parameters (α, β, γ and τ). The equations can predict the SCF around the T-joint's brace axis with an error of less than 8% and a root mean square error (RMSE) of less than 0.05.
Originality/value
Accurate SCF estimation for determining the fatigue life of offshore structures reduces the risks associated with fatigue failure while ensuring their durability and dependability. The current study provides a systematic approach for calculating the stress distribution at the weld toe and SCF in T-joints using FEA and ANN, as ANNs are better at approximating complex phenomena than typical data fitting techniques. Having a database of parametric equations enables fast estimation of SCFs, as opposed to costly testing and time-consuming FEA
The effect of democracy and corruption paradox on economic growth: MINT countries
No full textThis study examines the impact of democracy and corruption on the economic growth of Mexico, Indonesia, Nigeria, and Turkey over the 1975–2022 period. Utilizing the Fractional Frequency Flexible Fourier Panel Cointegration and Dynamic Ordinary Least Squares coefficient estimator, two models are employed to test hypotheses regarding economic growth. The findings reveal that democracy plays an upgrading role in the economic growth of all MINT countries, while the effect of corruption varies. In Indonesia and Mexico, corruption has a positive impact on growth, reflecting the effect of democracy, whereas Nigeria and Turkey experience a negative impact. The democracy model supports the compatibility hypothesis for all countries, asserting a positive link between democracy and economic growth. However, the corruption model yields divergent results, with Nigeria and Turkey aligning with the “grease in the wheels” hypothesis, implying that corruption can facilitate economic growth by bypassing bureaucratic obstacles, while Indonesia and Mexico support the "sand in the wheels" hypothesis, indicating that corruption hinders economic growth. This highlights the need for governments to strengthen institutions through transparency, accountability, and credibility via robust oversight and governance mechanisms. Therefore, democratic advancement, streamlined bureaucracy, and anti-corruption policies are imperative for sustainable economic growth and welfare
Induced voltage in piezoelectric tube driven segments and their use in nanopositioning, an assessment
No full textA piezoelectric tube actuator has a number of segments or electrodes. The induced voltage and the piezoelectric voltage, two easy-to-measure electrical signals in piezoelectric tubes, have been used in position estimation of these actuators since 2006 and 1982. However, since introduction, the in-duced voltage has never been compared with the piezoelectric voltage for piezoelectric tubes’ po-sition estimation. In addition, only linear models have been used to present the relationship between the induced voltage and the position of piezoelectric tubes. In other words, in the literature, it has been practically assumed that (1) the relationship between the induced voltage and the position is linear, and (2) the induced voltage can estimate the position more accurately compared to the piezoelectric voltage. This article assesses and nullifies both these assumptions. In this research, with the use of the experimental data, both aforementioned voltage signals were mapped into the position through linear and nonlinear models. It was shown that the position can be estimated less accurately with the induced voltage compared to the piezoelectric voltage, and the relationship of the position with the induced voltage presents higher and non-negligible nonlinearity compared to the one with the piezoelectric voltag
FIVADMI: A Framework for In-Vehicle Anomaly Detection by Monitoring and Isolation
No full textSelf-driving vehicles have attracted significant attention in the automotive industry that is heavi-ly investing to reach the level of reliability needed from these safety critical systems. Security of in-vehicle communications is mandatory to achieve this goal. Most of the existing research to de-tect anomalies for in-vehicle communication does not take into account the low processing power of the in-vehicle Network and ECUs (Electronic Control Units). Also, these approaches do not consider system level isolation challenges such as side-channel vulnerabilities, that may arise due to adoption of new technologies in the automotive domain. This paper introduces and discusses the design of a framework to detect anomalies in in-vehicle communications, including side channel attacks. The proposed framework supports real time monitoring of data exchanges among the components of in-vehicle communication network and ensures the isolation of the components in in-vehicle network by deploying them in Trusted Execution Environments (TEEs). The framework is designed based on the AUTOSAR open standard for automotive software ar-chitecture and framework. The paper also discusses the implementation and evaluation of the proposed framework
Infant embodied requests and teacher-practitioner offers during early childhood education mealtimes
No full textThe importance of building healthy relationships with food in children's early years is of paramount importance. Building on prior work exploring the social and linguistic practices in infant eating interaction experiences, this research uses a multimodal conversation analysis approach to explore how mealtime interactions are managed as a co-constructed activity between infants (0–2 years) and early childhood teacher-practitioners. Here we will explore video data recorded during mealtimes in an early childhood setting in Mid-Wales, where infants orient to recruitments for assistance and teachers provide offers of help with food items throughout the data. Analysis demonstrates 1) infant recruitment of help through embodied ‘showing’ an item causing a problem in multimodal ways, initiating joint attention that mobilises an offer from an adult in the shape of ‘do you want me to X’ and 2) adult initiation of an offer of help in the shape of ‘would you like me to X’ that are not prompted by infants ‘showing’ an item. Such practices demonstrate infant social competence in recruiting assistance through multimodal resources, and adult's noticings that help is required and their initiation of provision of assistance. The detailed exploration into the ways in which mealtimes are a collaboratively achieved experience reveals how infants effectively contribute in resourceful ways, and how teacher-practitioner responses frame mealtimes as co-produced activities
The Effects of a Carbohydrate Hydrogel System for the Delivery of Bicarbonate Mini-Tablets on Acid–Base Buffering and Gastrointestinal Symptoms in Resting Well-trained Male Cyclists
No full textBackground
A new commercially available sodium bicarbonate (SB) supplement claims to limit gastrointestinal (GI) discomfort and increase extracellular buffering capacity. To date, no available data exists to substantiate such claims. Therefore, the aim of this study was to measure blood acid–base balance and GI discomfort responses following the ingestion of SB using the novel “Bicarb System” (M-SB). Twelve well-trained male cyclists completed this randomised crossover designed study. Maximal oxygen consumption was determined in visit one, whilst during visits two and three participants ingested 0.3 g∙kg−1 BM SB using M-SB (Maurten, Sweden) or vegetarian capsules (C-SB) in a randomised order. Finger prick capillary blood samples were measured every 30 min for pH, bicarbonate (HCO3−), and electrolytes (potassium, chloride, calcium, and sodium), for 300 min. Visual analogue scales (VAS) were used to assess GI symptoms using the same time intervals.
Results
Peak HCO3− was 0.95 mmol∙L−1 greater following M-SB (p = 0.023, g = 0.61), with time to peak HCO3− achieved 38.2 min earlier (117 ± 37 vs. 156 ± 36 min; p = 0.026, r = 0.67) and remained elevated for longer (p = 0.043, g = 0.51). No differences were observed for any electrolytes between the conditions. Aggregated GI discomfort was reduced by 79 AU following M-SB (p < 0.001, g = 1.11), with M-SB reducing stomach cramps, bowel urgency, diarrhoea, belching, and stomach-ache compared to C-SB.
Conclusions
This is the first study to report that M-SB can increase buffering capacity and reduce GI discomfort. This presents a major potential benefit for athletes considering SB as an ergogenic supplement as GI discomfort is almost eliminated. Future research should determine if M-SB is performance enhancing
The Effects of a Novel Sodium Bicarbonate Ingestion System on Repeated 4 km Cycling Time Trial Performance in Well-Trained Male Cyclists
No full textBackground
A novel sodium bicarbonate (SB) product has come to market named the “Bicarb System” (M-SB; Maurten AB, Gothenburg, Sweden). It claims to minimise gastrointestinal (GI) discomfort whilst still improving exercise performance.
Aim
To investigate the effects of M-SB ingestion on repeated 4 km cycling time trials (TT1 and TT2) in well-trained male cyclists.
Methods
The study recruited ten well-trained cyclists (maximal oxygen uptake (
): 67 ± 4 ml kg−1 min−1 BM; peak power output (PPO) at
: 423 ± 21 W) to take part in this randomised, crossover and double-blinded study. Following one visit to determine
, participants completed a second visit to identify individual time to peak blood bicarbonate (HCO3−) (ITTP) in a rested state. Visit three was a familiarisation trial mimicking the experimental procedures. Visits four to seven consisted of completing 2 × 4 km cycling TTs separated by 45 min passive recovery, following one of either: 0.3 g kg−1 BM M-SB, 0.21 g kg−1 BM sodium chloride (placebo; PLA) in vegetarian capsules (size 00), or a control trial (CON). Supplements (M-SB or placebo) were ingested pre-exercise at their respective ITTP.
Results
Performance in TT1 was faster in the M-SB condition compared with TT1 in CON (− 5.1 s; p = 0.004) and PLA (− 3.5 s; p < 0.001). In TT2, performance was also significantly faster in the M-SB condition compared with CON (− 4.4 s; p = 0.018) or PLA (− 4.1 s; p = 0.002). Total aggregated GI symptoms were generally low and not significantly different between PLA and the M-SB conditions for a range of symptoms.
Conclusions
The ingestion of M-SB improves repeated 4 km cycling TT performance and the recovery of acid–base balance between bouts, whilst causing minimal GI discomfort
An Exploration of a Mentoring Programme for At-Risk Adolescents in the West Midlands, UK
No full textExtra-curricular activities, such as playing sport and participating in mentoring programmes, have physical and mental health benefits for individuals. For adolescents particularly, nurturing these interests have potential for positive outcomes in academic attainment and personal development, an increase to self-esteem, and positive development of relationship skills. This study explored the understanding and attitudes that 11 adolescents, aged 13 to 16 years, enrolled on a West Midlands-based charity’s sports and mentoring programme, had towards their participation through the form of semi-structured focus groups. Thematic Analysis was performed, and three key themes were identified: (i) Positive changes to their behaviour, (ii) Connections with the mentors, and (iii) The difference the mentoring programme has made to their lives. The findings demonstrated that the mentoring programme was beneficial and had favourable impact on the adolescents involved, and support the need for such programmes to be further developed and promoted for youth to access
The Interplay between Digital Technologies, Supply Chain Resilience, Robustness and Sustainable Environmental Performance: Does Supply Chain Complexity Matter?
No full textThis study aims to investigate the mediating role of supply chain resilience and robustness on the relationship between the use of digital technologies and sustainable environmental performance. Additionally, it investigates the moderating role of supply chain complexity on the impact of digital technologies on supply chain resilience and robustness. Data were gathered from 292 supply chain managers at registered manufacturing companies in Egypt and analyzed using Smart-PLS 4 software. The findings reveal that supply chain resilience and robustness partially mediate the link between digital technologies and sustainable environmental performance. Moreover, supply chain complexity was found to positively moderate the effect of digital technologies on both resilience and robustness. The model explained 53.2% of the variance in supply chain robustness, 56.6% in supply chain resilience, and 72.3% in sustainable environmental performance. These results provide critical insights for corporate policymaking, helping to drive continuous improvements in supply chain management, environmental performance, and sustainable development
Effects of Dietary Nitrate Supplementation on High-Intensity Cycling Sprint Performance in Recreationally Active Adults: A Systematic Review and Meta-Analysis
No full textThis systematic review and meta-analysis investigated the influence of dietary nitrate supplementation on performance metrics during cycling sprint exercise according to the PRISMA guidelines. Searches were conducted on MEDLINE, PubMed, ScienceDirect, Scopus, and SPORTDiscus databases up to September 2023. Inclusion criteria were healthy recreationally active men and women who consumed nitrate-rich and nitrate-deficient beetroot juice to assess performance outcomes of mean power, peak power, time-to-peak power, and minimum power during 30-s cycling sprints. Risk of bias was assessed using the Cochrane Risk of Bias 2 and TESTEX tools and funnel plots. A random effects model was performed on six studies and showed that dietary nitrate had significant effects on time-to-peak power (SMD: −0.66, 95% CI: −1.127 to −0.192, p = 0.006) but not on mean power, peak power, or minimum power. Subgroup analysis revealed that an acute low nitrate dose improved time-to-peak power (SMD: −0.977, 95% CI: −1.524 to −0.430, p < 0.001) but not after a multiday moderate nitrate dose (SMD: −0.177, 95% CI: −0.619 to −0.264, p = 0.431). These data suggest that acute nitrate supplementation can benefit time-to-peak power during 30-s cycling sprints, but due to the limited availability of data and heterogeneity in methodology, these results should be interpreted with caution. There was insufficient data on women to analyze sex-based differences. Future studies are required to provide insight on how supplementation regimen and population impact the effects of dietary nitrate for enhancing cycling sprint performance