The Airbus A320 family fan cowl door safety modification: a human factors scenario analysis

Purpose The Airbus A320 family engine fan cowl doors (FCDs) safety issue is known to the industry for almost 18 years; however, it has not been addressed adequately by the aircraft manufacturer and the various operators and regulating authorities. The purpose of this paper is to examine in a systematic way the possible operational and safety implications of a new modification on the engine FCDs. Design/methodology/approach An array of error-prone scenarios is presented and analysed under the prism of human factors in a non-exhaustive qualitative scenario analysis. Findings All examined scenarios are considered more or less probable. A number of accident prevention solutions are proposed for each of the scenario examined, in view of the acceptance and implementation of this modification by operators. Research limitations/implications As these scenarios are neither exhaustive nor have been tested/validated in actual aircraft maintenance practice, the further analysis is necessary. A substantial follow-up survey should take place, which should include a wider array of scenarios. This would allow obtaining the necessary data for a quantitative (statistical) analysis. Practical implications This case study identifies issues in relation to this modification, introduced by Airbus and the European Aviation Safety Agency (EASA), which may prove problematic from the point of view of safety effectiveness and disruption of operations. Originality/value This case study examines a long-standing aviation safety issue and the implications of a solution proposed by the aircraft manufacturer and adopted by EASA. This can be useful in increasing the awareness around these issues and highlight the importance of a human-centric and scenario-based design of engineering modifications towards minimising error in aircraft technical operations

Estimation in high dimensions: a geometric perspective

This tutorial provides an exposition of a flexible geometric framework for high dimensional estimation problems with constraints. The tutorial develops geometric intuition about high dimensional sets, justifies it with some results of asymptotic convex geometry, and demonstrates connections between geometric results and estimation problems. The theory is illustrated with applications to sparse recovery, matrix completion, quantization, linear and logistic regression and generalized linear models.Comment: 56 pages, 9 figures. Multiple minor change

Post-earnings announcement drift in Greece

This paper presents evidence regarding the post-earnings announcement drift (PEAD) anomaly for the Greek market in the years 2000–2006 (covering earnings announcements in the years 2001–2007). The impact of the introduction of International Financial Reporting Standards on the size and prevalence of the PEAD anomaly is examined. Unlike recent evidence for the US market we find PEAD to be alive and well, and of growing importance in our Greek sample. It may be the adoption of international financial reporting standards (IFRS) has served to reduce earnings predictability in Greece and thus enhance PEAD in the Athens stock exchange (ASE) market. This contrasts strongly with US evidence that the post earnings- announcement drift anomaly is now waning as more efficient markets and smarter, fundamentals-based, traders arbitrage its impact on stock prices

Strain and damage monitoring in CFRP fuselage panels using fiber Bragg grating sensors. Part I: Design, manufacturing and impact testing

This is the first paper of a two-paper series describing design, implementation and validation of a strain and damage monitoring system for CFRP fuselage stiffened panels based on fiber optic Bragg grating sensors. The monitoring system was developed and tested on the basis of three load-scenarios: compression to failure of the undamaged panel, compression to failure of the impacted panel and compression to failure of the impacted and fatigued panel. This paper focuses on the design of the fuselage panel, the design of the monitoring system, the embedment of fiber sensors in the panel during manufacturing and the impact testing. The network of the sensors was designed based on a numerical buckling analysis from which the strain field of the panel was computed as a function of the applied compressive load. Embedment of fiber sensors in the panel was done so as to minimize risk of fiber breaking during manufacturing and impact testing and to effectively capture strains that are representative of damage developed in the panel due to compressive load. Barely visible and visible low velocity impact damage sites were created at different locations of the panel using a drop-weight impactor. The panels were inspected using C-scan just after manufacturing, to check quality of the material, and just after impact testing to detect impact damage at each location

Discrete element modelling (DEM) for masonry infilled steel frames with multiple window openings subjected to lateral load variations

Steel framed structures are routinely infilled with masonry or concrete walls. The infill offers in-plane shear resistance that adds to the one from the steel frame. However, the stiffness effect on the entire frame’s response is usually neglected. In recent years, researchers have recognised the lack of in-depth understanding on infilled steel frames; hence specialised computational tools have been developed to provide an easy way of assessing these interactive structural systems and aid practising engineers in evaluating the overall behaviour. A computational model to study the behaviour of masonry infilled steel frames for the non-standard case of variable potential positions of openings and their interaction, when subjected to in-plane monotonic loading, is herein developed. Using the Discrete Element Method (DEM) and the software UDEC, the masonry wall is modelled as an assemblage of distinct deformable blocks while the mortar joints as zero thickness interfaces. The numerical model validated against full scale experimental tests found in the literature and a good agreement obtained. In addition, a series of parametric studies were performed to draw the significance of the size and location of the openings on the lateral load capacity, as well as the stiffness and failure mechanisms of the infilled steel frames. From the results analyses, it was found that the inclusion of multiple openings significantly reduces the strength and stiffness of the system. In particular, placing an opening close to the point of application of the lateral load will result to further reduction of masonry infill’s stiffness

Discrete element modelling of masonry infilled steel frames with multiple window openings subjected to lateral load variations

Steel framed structures are routinely infilled with masonry or concrete walls. The infill offers in-plane shear resistance that adds to the one from the steel frame. However, the stiffness effect on the entire frame's response is usually neglected. In recent years, researchers have recognised the lack of in-depth understanding on infilled steel frames; hence specialised computational tools have been developed to provide an easy way of assessing these interactive structural systems and aid practising engineers in evaluating the overall behaviour. A computational model to study the behaviour of masonry infilled steel frames for the non-standard case of variable potential positions of openings and their interaction, when subjected to in-plane monotonic loading, is herein developed. Using the Discrete Element Method (DEM) and the software UDEC, the masonry wall is modelled as an assemblage of distinct deformable blocks while the mortar joints as zero thickness interfaces. The numerical model validated against full scale experimental tests found in the literature and a good agreement obtained. In addition, a series of parametric studies were performed to draw the significance of the size and location of the openings on the lateral load capacity, as well as the stiffness and failure mechanisms of the infilled steel frames. From the results analyses, it was found that the inclusion of multiple openings significantly reduces the strength and stiffness of the system. In particular, placing an opening close to the point of application of the lateral load will result to further reduction of masonry infill's stiffness

Social synchronization of brain activity increases during eye-contact

Humans make eye-contact to extract information about other people’s mental states, recruiting dedicated brain networks that process information about the self and others. Recent studies show that eye-contact increases the synchronization between two brains but do not consider its effects on activity within single brains. Here we investigate how eye-contact affects the frequency and direction of the synchronization within and between two brains and the corresponding network characteristics. We also evaluate the functional relevance of eye-contact networks by comparing inter- and intra-brain networks of friends vs. strangers and the direction of synchronization between leaders and followers. We show that eye-contact increases higher inter- and intra-brain synchronization in the gamma frequency band. Network analysis reveals that some brain areas serve as hubs linking within- and between-brain networks. During eye-contact, friends show higher inter-brain synchronization than strangers. Dyads with clear leader/follower roles demonstrate higher synchronization from leader to follower in the alpha frequency band. Importantly, eye-contact affects synchronization between brains more than within brains, demonstrating that eye-contact is an inherently social signal. Future work should elucidate the causal mechanisms behind eye-contact induced synchronization

Bird strike virtual testing for preliminary airframe design

Abstract Purpose – The purpose of this paper is to use numerical methods early in the airframe design process and access the structural performance of wing leading edge devices made of different materials and design details, under bird strike events. Design/methodology/approach – Explicit finite element analysis was used to numerically model bird strike events. Findings – Structural performance charts related to materials and general design details were drawn to explore the design space dictated by the current applicable airworthiness requirements. Practical implications – This paper makes use of the current capability in the numerical tools available for structural simulations and exposes the existing limitations in the terms of material modelling, material properties and fracture simulation using continuum damage mechanics. Such results will always be in the need of fine-tuning with experimental testing, yet the tools can shed some light very early in the design process in a relative inexpensive manner, especially for design details down selection like materials to use, structural thicknesses and even design arrangements. Originality/value – Bird strike simulations have been successfully used on aircraft design, mainly at the manufactured articles design validation, testing and certification. This paper presents a hypothetical early design case study of leading edge devices for appropriate material and skin thickness down selectio

Social synchronization of brain activity increases during eye-contact

Copyright © The Author(s) 2022. Humans make eye-contact to extract information about other people’s mental states, recruiting dedicated brain networks that process information about the self and others. Recent studies show that eye-contact increases the synchronization between two brains but do not consider its effects on activity within single brains. Here we investigate how eye-contact affects the frequency and direction of the synchronization within and between two brains and the corresponding network characteristics. We also evaluate the functional relevance of eye-contact networks by comparing inter- and intra-brain networks of friends vs. strangers and the direction of synchronization between leaders and followers. We show that eye-contact increases higher inter- and intra-brain synchronization in the gamma frequency band. Network analysis reveals that some brain areas serve as hubs linking within- and between-brain networks. During eye-contact, friends show higher inter-brain synchronization than strangers. Dyads with clear leader/follower roles demonstrate higher synchronization from leader to follower in the alpha frequency band. Importantly, eye-contact affects synchronization between brains more than within brains, demonstrating that eye-contact is an inherently social signal. Future work should elucidate the causal mechanisms behind eye-contact induced synchronization.BIAL Foundation (No. 138/18); Leverhulme Trust Research Fellowship