Classification of damage in structural systems using time series analysis and supervised and unsupervised pattern recognition techniques

Peer reviewedPostprin

Economic Importance of Air Transport and Airport Activities in Belgium. NBB Working Papers. No. 158, 10 March 2009

This study is a publication issued by the Microeconomic Analysis service of the National Bank of Belgium, in partnership with the Department of Transport and Regional Economics of the University of Antwerp (UA). It is the outcome of a first research project on the Belgian airport and air transport sector. The former relates to the economic activities within the airports of Antwerp, Brussels, Charleroi, Kortrijk, Liège and Ostend, while the latter concentrates on the air transport business as a whole. In the past few years, the logistics business has come to play a significant part in income creation in our country, whose economy is to a large extent driven by services. Air transport and airports in particular are driving forces in this context, not only in terms of business generated within the air transport cluster, but also in terms of airports' attractiveness. On world scale an overall growth of cargo and passengers could be observed in the last ten years. However, the air transport sector has undergone a major crisis during the 2001-2003 period, when passenger traffic numbers first fell sharply and then stagnated. Only after 2003 this activity has picked up again and this until the third quarter of 2008. Cargo traffic on its part recovered already in 2002. In Belgium, a similar evolution can be observed. It should be stressed however that between 1997 and 2007 cargo volumes grew much faster than passenger traffic did. The rankings of European airports underline the importance of cargo traffic for Belgium: In 2006 Brussels, Liège and Ostend-Bruges respectively occupy ranks 6, 8, and 20 in the European cargo airport top 20, while for passenger airports, Brussels can only be found at the end of the top 20. In this study, a sectoral approach has been followed by focusing, for every airport, on two major economic activity components: the air transport cluster on the one hand and other airport-related sectors on the other hand. In that respect, annual accounts data from the Central Balance Sheet Office were used for the calculation of direct effects, the social balance sheet analysis and the study of financial ratios. Due to an inevitable time lag in the data provision, the analysis was limited to 2006. Like in other sectoral studies published by the Bank, indirect effects have also been estimated on the basis of data from the National Accounts Institute. In 2006, the total activities under review –direct and indirect, inside and outside airports- accounted for roughly 6.2 billion euro, i.e. 2 p.c. of Belgium's GDP and domestic employment. Considering the direct effects only, these percentages both amounted to 0.8 p.c. The three major airports, i.e. Brussels, Charleroi and Liège, alone account for 95.2 p.c. of the direct value added generated by the six airports under review. They represent 0.5 p.c. of Belgian GDP and, taking account of the indirect effects, 1.1 p.c. of the national income. Furthermore, it has to be pointed out that most Belgian airports are specialised. While the airports of Liège and Ostend focus on air cargo, Charleroi Airport deals mostly with low-cost passenger transport. Moreover, the smaller regional airports like Antwerp and Kortrijk focus on business travel

A prescriptive approach to qualify and quantify customer value for value-based requirements engineering

Recently, customer-based product development is becoming a popular paradigm. Customer expectations and needs can be identified and transformed into requirements for product design with the help of various methods and tools. However, in many cases, these models fail to focus on the perceived value that is crucial when customers make the decision of purchasing a product. In this paper, a prescriptive approach to support value-based requirements engineering (RE) is proposed, describing the foundations, procedures and initial applications in the context of RE for commercial aircraft. An integrated set of techniques, such as means-ends analysis, part-whole analysis and multi-attribute utility theory is introduced in order to understand customer values in depth and width. Technically, this enables identifying the implicit value, structuring logically collected statements of customer expectations and performing value modelling and simulation. Additionally, it helps to put in place a system to measure customer satisfaction that is derived from the proposed approach. The approach offers significant potential to develop effective value creation strategies for the development of new product

Vibration-based damage detection in an aircraft wing scaled model using principal component analysis and pattern recognition

This study deals with vibration-based fault detection in structures and suggests a viable methodology based on principal component analysis (PCA) and a simple pattern recognition (PR) method. The frequency response functions (FRFs) of the healthy and the damaged structure are used as initial data. A PR procedure based on the nearest neighbour principle is applied to recognise between the categories of the damaged and the healthy wing data. A modified PCA method is suggested here, which not only reduces the dimensionality of the FRFs but in addition makes the PCA transformed data from the two categories more differentiable. It is applied to selected frequency bands of FRFs which permits the reduction of the PCA transformed FRFs to two new variables, which are used as damage features. In this study, the methodology is developed and demonstrated using the vibration response of a scaled aircraft wing simulated by a finite element (FE) model. The suggested damage detection methodology is based purely on the analysis of the vibration response of the structure. This makes it quite generic and permits its potential development and application for measured vibration data from real aircraft wings as well as for other real and complex structures

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 172

This bibliography lists 132 reports, articles, and other documents introduced into the NASA scientific and technical information system in September 1977

Economic Importance of Air Transport and Airport Activities in Belgium

This study is a publication issued by the Microeconomic Analysis service of the National Bank of Belgium, in partnership with the Department of Transport and Regional Economics of the University of Antwerp (UA). It is the outcome of a first research project on the Belgian airport and air transport sector. The former relates to the economic activities within the airports of Antwerp, Brussels, Charleroi, Kortrijk, Liège and Ostend, while the latter concentrates on the air transport business as a whole. In the past few years, the logistics business has come to play a significant part in income creation in our country, whose economy is to a large extent driven by services1. Air transport and airports in particular are driving forces in this context, not only in terms of business generated within the air transport cluster, but also in terms of airports' attractiveness. On world scale an overall growth of cargo and passengers could be observed in the last ten years. However, the air transport sector has undergone a major crisis during the 2001-2003 period, when passenger traffic numbers first fell sharply and then stagnated. Only after 2003 this activity has picked up again and this until the third quarter of 2008. Cargo traffic on its part recovered already in 2002. In Belgium, a similar evolution can be observed. It should be stressed however that between 1997 and 2007 cargo volumes grew much faster than passenger traffic did. The rankings of European airports underline the importance of cargo traffic for Belgium: In 2006 Brussels, Liège and Ostend-Bruges respectively occupy ranks 6, 8, and 20 in the European cargo airport top 20, while for passenger airports, Brussels can only be found at the end of the top 20. In this study, a sectoral approach has been followed by focusing, for every airport, on two major economic activity components: the air transport cluster on the one hand and other airport-related sectors on the other hand. In that respect, annual accounts data from the Central Balance Sheet Office were used for the calculation of direct effects, the social balance sheet analysis and the study of financial ratios. Due to an inevitable time lag in the data provision, the analysis was limited to 2006. Like in other sectoral studies published by the Bank, indirect effects have also been estimated on the basis of data from the National Accounts Institute. In 2006, the total activities under review –direct and indirect, inside and outside airports- accounted for roughly 6.2 billion euro, i.e. 2 p.c. of Belgium's GDP and domestic employment. Considering the direct effects only, these percentages both amounted to 0.8 p.c. The three major airports, i.e. Brussels, Charleroi and Liège, alone account for 95.2 p.c. of the direct value added generated by the six airports under review. They represent 0.5 p.c. of Belgian GDP and, taking account of the indirect effects, 1.1 p.c. of the national income. Furthermore, it has to be pointed out that most Belgian airports are specialised. While the airports of Liège and Ostend focus on air cargo, Charleroi Airport deals mostly with low-cost passenger transport. Moreover, the smaller regional airports like Antwerp and Kortrijk focus on business travel. The analysis was completed in December 2008air transport, airport activities, sector analysis, indirect effect, public investments UA,

A problem-structuring model for analyzing transportation–environment relationships

This is the post-print version of the final paper published in European Journal of Operational Research. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2009 Elsevier B.V.This study discusses a decision support framework that guides policy makers in their strategic transportation related decisions by using multi-methodology. For this purpose, a methodology for analyzing the effects of transportation policies on environment, society, economy, and energy is proposed. In the proposed methodology, a three-stage problem structuring model is developed. Initially, experts’ opinions are structured by using a cognitive map to determine the relationships between transportation and environmental concepts. Then a structural equation model (SEM) is constructed, based on the cognitive map, to quantify the relations among external transportation and environmental factors. Finally the results of the SEM model are used to evaluate the consequences of possible policies via scenario analysis. In this paper a pilot study that covers only one module of the whole framework, namely transportation–environment interaction module, is conducted to present the applicability and usefulness of the methodology. This pilot study also reveals the impacts of transportation policies on the environment. To achieve a sustainable transportation system, the extent of the relationships between transportation and the environment must be considered. The World Development Indicators developed by the World Bank are used for this purpose

Construction and application of a questionnaire for the social scientific investigation of environmental noise effects

A social psychological questionnair has been developed to study the effects of environmental noise and was applied to 636 people living in 19 different areas of Hamburg. The theoretical foundations and the statistical means employed in its development are described. Four main reactions to noise are isolated statistically, and it is determined that these are moderated by several intervening variables, chief of which are coping capacity for noise, the perceived dangerousness of the noise souce, other daily loads and the individual's liability