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Study of alternatives and experimental validation for predictions of hole-edge fatigue crack growth in 42CrMo4 steel
Get PDFThe objective of this work is to establish pertinent criteria allowing an optimal alternative to be chosen for calculating the inputs needed to make Run/Repair/Replace decisions and to program inspection plans for cracked wind turbine bearing rings. With this aim, the growth of a hole-edge through-crack was predicted analytically, simulated and measured in a 42CrMo4 steel plate subjected to mode-I cyclic loading. Different alternative procedures according to BS 7910:2013 fitness-for-service code were implemented. Unexpectedly, the numerical calculation of the local stresses in the uncracked body did not improve the estimations of the critical crack length and the number of cycles to failure performed following purely analytical alternatives. That alternative underestimated the critical crack length by 50%. Among the alternatives studied, the one based on numerically calibrated stress intensity factors and crack growth coefficients characterized at the corresponding stress ratios proved to be the most suitable one. Following that alternative, the fatigue life was found to be overestimated by 3.96% in the best scenario whereas the critical crack length was underestimated with an error less than 3%, determined using the Failure Assessment Diagram (FAD) as a failure criterion
An Accurate Shock Advise Algorithm for Use During Piston-Driven Chest Compressions
Get PDFMechanically delivered chest compressions induce artifacts in the ECG that can lead to an incorrect diagnosis of the shock advice algorithms implemented in the defibrillators. This forces the rescuer to stop cardiopulmonary resuscitation (CPR) compromising circulation and thus reducing the probability of survival. This paper introduces a new approach for a reliable rhythm analysis during mechanical compressions which consists of an artifact supression filter based on the recursive least squares algorithm, and a shock/no-shock decision algorithm based on machine learning techniques that uses features obtained from the filtered ECG. Data were collected from 230 out-of-hospital cardiac arrest patients treated with the LUCAS CPR device. The underlying rhythms were annotated in artifact-free intervals by consesus of expert resuscitation rhythm reviewers. Shock/no-shock diagnoses obtained through the decision algorithm were compared with the rhythm annotations to obtain the sensitivity (Se), specificity (Sp) and balanced accuracy (BAC) of the method. The results obtained were: 94.7% (Se), 97.1% (Sp) and 95.9% (BAC)
Aging effects on resting state networks after an emotional memory task
Get PDFAging is one of the primary health concerns in nowadays world, being memory decline an important worry that affects daily functioning of healthy adults. This work presents a study of this kind of decline in normal aging, by processing and analysing electroencephalographs (EEGs) of 72 healthy subjects, categorized as either young or older adults. These biosignals are first pre-processed using a customized pre-processing pipeline using the EEGLAB tool in Matlab. Once the signals have been pre-processed, two different analyses are carried out: a frequency analysis, obtaining the powers for each band of the EEG signals, and a time-frequency analysis. The data obtained from these studies is analysed using R, obtaining some important results and conclusions
Cost-effectiveness and budget impact analyses of a colorectal cancer screening programme in a high adenoma prevalence scenario using MISCAN-Colon microsimulation model
Get PDFThis economic evaluation showed a screening intervention with a major health gain that also produced net savings when a long follow-up was used to capture the late economic benefit. The number of colonoscopies required was high but remain within the capacity of the Basque Health Service. So far in Europe, no other population Colorectal Cancer screening programme has been evaluated by budget impact analysis
Analysis of One-Way and Two-Way FSI Approaches to Characterise the Flow Regime and the Mechanical Behaviour during Closing Manoeuvring Operation of a Butterfly Valve
Get PDFButterfly valves are widely used industrial piping components as on-off and flow controlling devices. The main challenge in the design process of this type of valves is the correct dimensioning to ensure proper mechanical performance as well as to minimise flow losses that affect the efficiency of the system. Butterfly valves are typically dimensioned in a closed position based on mechanical approaches considering uniform hydrostatic pressure, whereas the flow losses are analysed by means of CFD simulations. The main limitation of these approaches is that they do not consider either the influence of the dynamics of the manoeuvring stage or coupled phenomena. Recent works have included the influence of the flow on the mechanical behaviour for different opening angles by means of one-way FSI approach. However, these works consider steady-state flow for the selected angles, not capturing the effect of the transient flow evolution during the manoeuvring stage. Two-way FSI modelling approach could allow overcoming such limitations providing more accurate results. Nevertheless, the use of this technique is limited due to the increase in the computational cost. In the present work, the applicability of FSI one-way and two-way approaches is evaluated for the analysis of butterfly valves, showing that not considering fluid-structure coupling involves not capturing the most critical situation for the valve disc
Aesthetic interaction consistency: exploring the foundation for static and dynamic aesthetics
Get PDFAesthetics is a powerful means for creating consistency across a product range. During the design process consistency is subject to risk. The existing tools do not integrate static as well as dynamic approaches. This paper explores how to integrate and combine both. The framework considers that, firstly, the users perceive the product thought all their senses (product presentation). Based on the perceptions, users will interact through gestures or movements (user action). These action will create a product reaction (product reaction). Finally, the frame has been applied in an experiment
Evaluating inclusivity using quantitative personas
Get PDFExclusion assessment is a powerful method for assessing inclusivity in a quantitative way. However, its focus on capability data makes it difficult to consider the effect of other factors such as different ways of using a product. We propose addressing this by combining exclusion assessment with quantitative personas. Each persona represents a group of people with similar capabilities, and is enhanced with other personal information. The capabilities of each persona are compared against the product demands to assess whether they (and thus the group they represent) could do a task. The additional persona information helps to determine how they approach and conduct the task. By examining personas that cover the whole of the target population, it is possible to estimate the proportion of that population who could complete the task. We present a proof-of-concept study using personas created from Disability Follow-up Survey data. These were used to assess the task of carrying a tray of food across a cafe, taking into account how using mobility aids restricts hand use
