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See detailWeakening the tight coupling between geometry and simulation in isogeometric analysis
Bordas, Stéphane UL; Tomar, Satyendra UL; Atroshchenko, Elena et al

Scientific Conference (2016, June 05)

In the standard paradigm of isogeometric analysis, the geometry and the simulation spaces are tightly integrated, i.e. the same non-uniform rational B-splines (NURBS) space, which is used for the geometry ... [more ▼]

In the standard paradigm of isogeometric analysis, the geometry and the simulation spaces are tightly integrated, i.e. the same non-uniform rational B-splines (NURBS) space, which is used for the geometry representation of the domain, is employed for the numerical solution of the problem over the domain. However, there are situations where this tight integration is a bane rather than a boon. Such situations arise where, e.g., (1) the geometry of the domain is simple enough to be represented by low order NURBS, whereas the unknown (exact) solution of the problem is sufficiently regular, and thus, the numerical solution can be obtained with improved accuracy by using NURBS of order higher than that required for the geometry, (2) the constraint of using the same space for the geometry and the numerical solution is particularly undesirable, such as in the shape and topology optimization, and (3) the solution of the problem has low regularity but for the curved boundary of the domain one can employ higher order NURBS. Therefore, we propose to weaken this constraint. An extensive study of patch tests on various combinations of polynomial degree, geometry type, and various cases of varying degrees and control variables between the geometry and the numerical solution will be discussed. It will be shown, with concrete reasoning, that why patch test fails in certain cases, and that those cases should be avoided in practice. Thereafter, selective numerical examples will be presented to address some of the above-mentioned situations, and it will be shown that weakening the tight coupling between geometry and simulation offers more flexibility in choosing the numerical solution spaces, and thus, improved accuracy of the numerical solution. Powered by [less ▲]

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See detailWeakening the tight coupling between geometry and simulation in isogeometric analysis: from sub- and super- geometric analysis to Geometry Independent Field approximaTion (GIFT)
Atroshchenko, Elena; Tomar, Satyendra UL; Xu, Gang et al

in International Journal for Numerical Methods in Engineering (2018)

This paper presents an approach to generalize the concept of isogeometric analysis (IGA) by allowing different spaces for parameterization of the computational domain and for approximation of the solution ... [more ▼]

This paper presents an approach to generalize the concept of isogeometric analysis (IGA) by allowing different spaces for parameterization of the computational domain and for approximation of the solution field. The method inherits the main advantage of isogeometric analysis, i.e. preserves the original, exact CAD geometry (for example, given by NURBS), but allows pairing it with an approximation space which is more suitable/flexible for analysis, for example, T-splines, LR-splines, (truncated) hierarchical B-splines, and PHT-splines. This generalization offers the advantage of adaptive local refinement without the need to re-parameterize the domain, and therefore without weakening the link with the CAD model. We demonstrate the use of the method with different choices of the geometry and field splines, and show that, despite the failure of the standard patch test, the optimum convergence rate is achieved for non-nested spaces. [less ▲]

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See detailWeakening the tight coupling between geometry and simulation in isogeometric analysis: from sub- and super- geometric analysis to Geometry Independent Field approximaTion (GIFT)
Atroshchenko, Elena; Xu, Gang; Tomar, Satyendra UL et al

E-print/Working paper (n.d.)

This paper presents an approach to generalize the concept of isogeometric analysis (IGA) by allowing different spaces for parameterization of the computational domain and for approximation of the solution ... [more ▼]

This paper presents an approach to generalize the concept of isogeometric analysis (IGA) by allowing different spaces for parameterization of the computational domain and for approximation of the solution field. The method inherits the main advantage of isogeometric analysis, i.e. preserves the original, exact CAD geometry (for example, given by NURBS), but allows pairing it with an approximation space which is more suitable/flexible for analysis, for example, T-splines, LR-splines, (truncated) hierarchical B-splines, and PHT-splines. This generalization offers the advantage of adaptive local refinement without the need to re-parameterize the domain, and therefore without weakening the link with the CAD model. We demonstrate the use of the method with different choices of the geometry and field splines, and show that, despite the failure of the standard patch test, the optimum convergence rate is achieved for non-nested spaces. [less ▲]

Detailed reference viewed: 123 (13 UL)
See detailWeakly Inscribed Polyhedra
chen, hao; Schlenker, Jean-Marc UL

E-print/Working paper (2017)

Detailed reference viewed: 14 (0 UL)
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See detailWealth accumulation over the life course. The role of disadvantages across the employment history
Ponomarenko, Valentina UL

E-print/Working paper (2017)

In this study wealth is employed as an often neglected but highly stratified well-being measure in sociology. I relate the employment history and especially the accumulating disadvantages like ... [more ▼]

In this study wealth is employed as an often neglected but highly stratified well-being measure in sociology. I relate the employment history and especially the accumulating disadvantages like nonemployment and lower occupations to wealth in old age. In particular, I am interested in determining whether an adverse employment history prevents wealth accumulation and which factors influence wealth accumulation across the life course. I use comparative data from the Survey of Health, Ageing and Retirement and combine it with the retrospective panel SHARELIFE to retrieve information about the complete employment history. The relevance of wealth varies significantly across households and in the wider national context. Hence, a contextual perspective is included to account for the difference in wealth rates and wealth inequality in the European countries. The results show that cumulative nonemployment and employment in lower occupations has significant disadvantages for wealth accumulation in old age. However, large differences for men and women persist. Particularly, the household composition and household factors are decisive in the effectuality of these disadvantages. The relation of life course employment and especially disadvantages to accumulated wealth in old aged is stronger in conservative countries than in other welfare regimes. [less ▲]

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See detailWealth Inequality: A Survey
Cowell, Frank A.; van Kerm, Philippe UL

in Journal of Economic Surveys (2015), 29(4), 671-710

We survey the issues involved in comparing wealth distributions and measuring wealth inequality with illustrations from the Eurosystem Household Finance and Consumption Survey.

Detailed reference viewed: 25 (1 UL)
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See detailWealth, Top Incomes, and Inequality
Cowell, Frank A.; Nolan, Brian; Olivera, Javier et al

in Hamilton, Kirk; Hepburn, Cameron (Eds.) National Wealth: What is Missing, Why it Matters (2017)

Although it is heartening to see wealth inequality being taken seriously, key concepts are often muddled, including the distinction between income and wealth, what is included in "wealth", and facts about ... [more ▼]

Although it is heartening to see wealth inequality being taken seriously, key concepts are often muddled, including the distinction between income and wealth, what is included in "wealth", and facts about wealth distributions. This chapter highlights issues that arise in making ideas and facts about wealth inequality precise, and employs newly-available data to take a fresh look at wealth and wealth inequality in a comparative perspective. The composition of wealth is similar across countries, with housing wealth being the key asset. Wealth is considerably more unequally distributed than income, and it is distinctively so in the United States. Extending definitions to include pension wealth however reduces inequality substantially. Analysis also sheds light on life-cycle patterns and the role of inheritance. Discussion of the joint distributions of income and wealth suggests that interactions between increasing top income shares and the concentration of wealth and income from wealth towards the top is critical. [less ▲]

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See detailA Wearable Revolution: Is the smartwatch the next small big thing?
Kracheel, Martin UL; Bronzi, Walter UL; Kazemi, Hamed

Article for general public (2014)

Smartwatches have the potential to enhance our digital lifestyle, but are not yet a part of our digital lifestyle. When big competitors overcome smartwatches usability challenges and design limitations ... [more ▼]

Smartwatches have the potential to enhance our digital lifestyle, but are not yet a part of our digital lifestyle. When big competitors overcome smartwatches usability challenges and design limitations, this could change rapidly. The smartwatch, to be successful, has to combine two requirements: provide digital information and individual expression presented by traditional watches. The smartwatch can excel in a new category of "smart" devices to be used instead of our smartphones for simplifying and speeding up activities such as reading a message, checking the weather, traffic directions or your agenda. The support from the community of developers will play a major role in deciding which platform will progress further. [less ▲]

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See detailWeaving Rules into Models@run.time for Embedded Smart Systems
Mouline, Ludovic UL; Hartmann, Thomas UL; Fouquet, François UL et al

in Mouline, Ludovic; Hartmann, Thomas; Fouquet, François (Eds.) et al Programming '17 Companion to the first International Conference on the Art, Science and Engineering of Programming (2017, April)

Smart systems are characterised by their ability to analyse measured data in live and to react to changes according to expert rules. Therefore, such systems exploit appropriate data models together with ... [more ▼]

Smart systems are characterised by their ability to analyse measured data in live and to react to changes according to expert rules. Therefore, such systems exploit appropriate data models together with actions, triggered by domain-related conditions. The challenge at hand is that smart systems usually need to process thousands of updates to detect which rules need to be triggered, often even on restricted hardware like a Raspberry Pi. Despite various approaches have been investigated to efficiently check conditions on data models, they either assume to fit into main memory or rely on high latency persistence storage systems that severely damage the reactivity of smart systems. To tackle this challenge, we propose a novel composition process, which weaves executable rules into a data model with lazy loading abilities. We quantitatively show, on a smart building case study, that our approach can handle, at low latency, big sets of rules on top of large-scale data models on restricted hardware. [less ▲]

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See detailWeb Application Vulnerability Prediction using Hybrid Program Analysis and Machine Learning
Shar, Lwin Khin UL; Briand, Lionel UL; Tan, Hee Beng Kuan

in IEEE Transactions on Dependable and Secure Computing (2015), 12(6), 688-707

Due to limited time and resources, web software engineers need support in identifying vulnerable code. A practical approach to predicting vulnerable code would enable them to prioritize security auditing ... [more ▼]

Due to limited time and resources, web software engineers need support in identifying vulnerable code. A practical approach to predicting vulnerable code would enable them to prioritize security auditing efforts. In this paper, we propose using a set of hybrid (static+dynamic) code attributes that characterize input validation and input sanitization code patterns and are expected to be significant indicators of web application vulnerabilities. Because static and dynamic program analyses complement each other, both techniques are used to extract the proposed attributes in an accurate and scalable way. Current vulnerability prediction techniques rely on the availability of data labeled with vulnerability information for training. For many real world applications, past vulnerability data is often not available or at least not complete. Hence, to address both situations where labeled past data is fully available or not, we apply both supervised and semi-supervised learning when building vulnerability predictors based on hybrid code attributes. Given that semi-supervised learning is entirely unexplored in this domain, we describe how to use this learning scheme effectively for vulnerability prediction. We performed empirical case studies on seven open source projects where we built and evaluated supervised and semi-supervised models. When cross validated with fully available labeled data, the supervised models achieve an average of 77% recall and 5% probability of false alarm for predicting SQL injection, cross site scripting, remote code execution and file inclusion vulnerabilities. With a low amount of labeled data, when compared to the supervised model, the semi- supervised model showed an average improvement of 24% higher recall and 3% lower probability of false alarm, thus suggesting semi-supervised learning may be a preferable solution for many real world applications where vulnerability data is missing. [less ▲]

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See detailWeb Hacking
Dagorn, Nathalie; Bernard, Nicolas UL

in Proceedings of the Fourth IADIS International Conference on the World Wide Web and the Internet (Internet/www 2005) (2005)

Detailed reference viewed: 52 (1 UL)
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See detailThe “Web of pros” in the 1990s: The professional acclimation of the World Wide Web in France
Schafer, Valerie UL; Thierry, Benjamin

in New Media & Society (2016), 18(7), 1143-1158

This article, focusing on France, explores the notion of a “Web of professionals” and seeks to establish its factual, epistemological, and methodological implications for the history of the World Wide Web ... [more ▼]

This article, focusing on France, explores the notion of a “Web of professionals” and seeks to establish its factual, epistemological, and methodological implications for the history of the World Wide Web in the 1990s. This research reflects on the promises of the New Economy and the roles of the various controversies, cultures, imaginaries, and forms of mediation affecting the business world in its appropriation of the Web. It also aims to reappraise the individual and collective stakeholders whose active part has been somehow underestimated or obscured by the image of the mass Internet user. The professionalization of Web activities, the development of a new generation of entrepreneurs and the conversion of business models to online practices are all significant parts of the emergent Web culture in France, as well as factors contributing to this emergence. [less ▲]

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See detailWeb Services Verification and Prudent Implementation
Avanesov, Tigran UL; Chevalier, Yannick; Anis Mekki, Mohammed et al

in Data Privacy Management and Autonomous Spontaneus Security - 6th International Workshop, DPM 2011, and 4th International Workshop, SETOP 2011, Leuven, Belgium, September 15-16, 2011, Revised Selected Papers. (2011)

Alice&Bob notation is widely used to describe conversations between partners in security protocols. We present a tool that compiles an Alice&Bob description of a Web Services choreography into a set of ... [more ▼]

Alice&Bob notation is widely used to describe conversations between partners in security protocols. We present a tool that compiles an Alice&Bob description of a Web Services choreography into a set of servlets. For that we first compute for each partner an executable specification as prudent as possible of her role in the choreography. This specification is expressed in ASLan language, a formal language designed for modeling Web Services tied with security policies. Then we can check with automatic tools that this ASLan specification verifies some required security properties such as secrecy and authentication. If no flaw is found, we compile the specification into Java servlets that real partners can use to execute the choreography. [less ▲]

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See detailA web-based quality control system for assessment processes
Busana, Gilbert UL; Koenig, Vincent UL; Martin, Romain UL et al

in International Journal of Psychology (2008), 43

Detailed reference viewed: 24 (1 UL)
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See detailA web-based system for mathematical problem understanding and solving
Busana, Gilbert UL; Martin, Romain UL; Langers, Christian UL

in International Journal of Psychology (2008), 43

In the domain of educational multimedia for primary school a lot of research has been done in the field of computer assisted calculation frameworks. However, much less work has been done in the area of ... [more ▼]

In the domain of educational multimedia for primary school a lot of research has been done in the field of computer assisted calculation frameworks. However, much less work has been done in the area of problem solving and especially in the area of problem understanding. The present project aims at the development and the scientific assessment of a computer assisted framework for mathematical problem understanding and solving (CAMPUS) based on analogical representations in form of number lines (Klein, Beishuizen, & Treffers, 1998; Petitto, 1990) and graphs. This tool will be deployed by our formerly developed computer assisted testing platform (http://www.tao.lu) [see our proposal on TAO] and will be the first learning tool on that system. The CAMPUS framework will help teachers to more efficiently analyze the different steps of the problem solving strategies of their students and thereby allow them to give more adapted feedback in order to guide the learner’s process. The main characteristic of this platform is the use of the computer as a framework for the development of problem solving strategies in mathematics. The tool imposes no restrictions in the resolution processes of the learner, but avoids him to get lost in those steps of solving that are obviously wrong (for example: addition of objects of different classes). In this way, the CAMPUS architecture is a sort of a cognitive tool that helps the student in structuring his thinking by telling him which calculations are mathematically or logically not permitted, but it does not suggest him a precise way towards the solution. In contrary, each logically correct action will be accepted by the system. Consequently, the CAMPUS tool is not a drill-and-practice tool, but it proposes a framework for the student in which he can develop problem solving strategies in complex situations. CAMPUS is based on a (socio-)cognitive approach, which means that the tool permits to solve the problems in an individual or a group situation, even if the teamwork is explicitly desirable in such a pedagogical approach (Webb, 1994; Yadrick, Regian, Connolly Gomez, & Robertson Schule, 1997). The tool is intended to be integrated into daily classroom teaching as a tool for triggering the learning process and therefore has not to be considered as a separate or additional exercising tool. The students learning process should be supported by the tool on one hand and by additional teacher support on the other hand. The learner and his learning process are at the centre of the learning activity (Tardif, 1998) and the teacher plays a supervision and support role in this sort of learning environment (Hudson, 1997; Tardif, 1998). Moreover, the use of analogical representations (of the operations to be taken) and graphs (representing the resolution steps adopted by the learner) should favour, on the learner’s side, the establishment of mental models including analogical representations and supporting the resolution process of this type of problems, even beyond the use of this computerized platform. We could expect that the learner will develop, through his experiences with the platform (which prevents experimentation with arbitrary meaningless calculations), thorough knowledge concerning the solving of mathematical problems based, at least partially, on non-explicit learning processes as described, for example, in the connectionist models of learning theories (Spitzer, 2000). These connectionist models show in fact that significant learning can be achieved in a non-explicit manner if the learner is placed in an environment which structures his behavior along certain regularities (even if these regularities are not taught in an explicit manner). The CAMPUS framework is based on a conceptual idea that emerged from previous research (Busana, 1999) where a prototype using a similar architecture has been developed in an alpha-version using Quest. This alpha-version was developed in only one language (German) and ran only under Windows. The new CAMPUS-tool will be published under the open-source licence, will be platform independent (plays in Macromedia’s Flash Player) and will be delivered over the Internet. [less ▲]

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See detailA web-based versus paper questionnaire on alcohol and tobacco in adolescents.
Lygidakis, Charilaos UL; Rigon, Sara; Cambiaso, Silvio et al

in Telemedicine journal and e-health : the official journal of the American Telemedicine Association (2010), 16(9), 925-30

OBJECTIVE: Our study was aimed at comparing health behavior data collected from a Web-based self-administered questionnaire (Web SAQ) versus a paper-and-pencil self-administered questionnaire and ... [more ▼]

OBJECTIVE: Our study was aimed at comparing health behavior data collected from a Web-based self-administered questionnaire (Web SAQ) versus a paper-and-pencil self-administered questionnaire and assessing the feasibility of the application. MATERIALS AND METHODS: One hundred and ninety (n = 190) pupils (ages 14-16 years) of senior high schools anonymously completed a questionnaire, with demographics and queries about lifestyle, alcohol, and tobacco use. For each class, the adolescents were randomly assigned to complete either the paper version of the questionnaire or the equivalent Web-based one, which used a customized platform developed for the purposes of this survey. RESULTS: Females who filled out the Web SAQ required significantly less time and completed a significantly higher percentage of its items. Although the majority of questions on tobacco and alcohol did not differ significantly across the two administration modes, there were gender-related differences in some sensitive information. Male adolescents on the Web SAQ accounted higher per hour drink consumption (r = 0.27, p = 0.015) and more numerous episodes of inebriety (r = 0.26, p = 0.010), whereas females seemed to state a younger age of alcohol onset (r = 0.33, p = 0.002). Females were more likely to report being monthly smokers on the Web SAQ (odds ratio = 0.37). Adolescents felt significantly less observed and females referred being more independent while compiling the Web SAQ. CONCLUSIONS: The findings of the study suggest that differences in reporting of some behavior of adolescents when using a Web SAQ do exist, despite the small-to-medium effect sizes. Exploiting the Web requires further investigation for extensive comprehension of the reasons for such differences. [less ▲]

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See detailWeber et Kelsen : de la prétention scientifique
Lefort, Elisabeth UL

Presentation (2013, March)

Detailed reference viewed: 12 (1 UL)
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See detailWeber Fraction as an index of the acuity of the ANS and its relationship to arithmetic performance by adults
Guillaume, Mathieu UL; Mussolin, Christophe; Nys, Julie et al

Scientific Conference (2012)

Detailed reference viewed: 37 (0 UL)
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See detailWebsite Fingerprinting at Internet Scale
Panchenko, Andriy UL; Lanze, Fabian UL; Zinnen, Andreas et al

in Proceedings of the 23rd Internet Society (ISOC) Network and Distributed System Security Symposium (NDSS 2016) (2016, February)

Detailed reference viewed: 308 (32 UL)