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See detailA smooth family of intertwining operators
Lahiani, Raza UL; Molitor-Braun, Carine UL

in Journal of the Mathematical Society of Japan [=JMSJ] (2011), 63(1), 321-361

Detailed reference viewed: 81 (4 UL)
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See detailsmooth nodal stress in the XFEM for crack propagation simulations
Peng, Xuan; Bordas, Stéphane UL; Natarajan, Sundararajan

Scientific Conference (2013, September)

In this paper, we present a method to achive smooth nodal stresses in the XFEM without post-processing. This method was developed by borrowing ideas from ``twice interpolating approximations'' (TFEM) [1 ... [more ▼]

In this paper, we present a method to achive smooth nodal stresses in the XFEM without post-processing. This method was developed by borrowing ideas from ``twice interpolating approximations'' (TFEM) [1]. The salient feature of the method is to introduce an ``average'' gradient into the construction of the approximation, resulting in improved solution accuracy, both in the vicinity of the crack tip and in the far field. Due to the high order polynomial basis provided by the interpolants, the new approximation enhances the smoothness of the solution without requiring an increased number of degrees of freedom. This is particularly advantageous for low-order elements and in fracture mechanics, where smooth stresses are important for certain crack propagation criteria, e.g. based on maximum principal stresses. Since the new approach adopts the same mesh discretization, i.e. simplex meshes, it can be easily extended into various problems and is easily implemented. We discuss the increase in the bandwidth which is the major drawback of the present method and can be somewhat alleviated by using an element-by-element solution strategy. Numerical tests show that the new method is as robust as XFEM, considering precision, model size and post-processing time. By comparing in detail the behaviour of the method on crack propagation examples, we can conclude that for two-dimensional problems, the proposed method tends to be an efficient alternative to the classical XFEM [2][3] especially when local, stress-based propagation criteria are used. [less ▲]

Detailed reference viewed: 368 (4 UL)
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See detailThe smoothed extended finite element method for strong discontinuities
Natarajan, S.; Bordas, Stéphane UL; Rabczuk, Timon

Scientific Conference (2009, June)

Detailed reference viewed: 92 (0 UL)
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See detailThe smoothed extended finite element method
Natarajan, S.; Bordas, Stéphane UL; Minh, Q. D. et al

in Proceedings of the 6th International Conference on Engineering Computational Technology (2008)

This paper shows how the strain smoothing technique recently proposed by G.R.Liu [1] coined as smoothed finite element method (SFEM) can be coupled to partition of unity methods, namely extended finite ... [more ▼]

This paper shows how the strain smoothing technique recently proposed by G.R.Liu [1] coined as smoothed finite element method (SFEM) can be coupled to partition of unity methods, namely extended finite element method (XFEM) [2] to give birth to the smoothed extended finite element method (SmXFEM), which shares properties both with the SFEM and the XFEM. The proposed method suppresses the need to compute and integrate the derivatives of shape functions (which are singular at the tip in linear elastic fracture mechanics). Additionally, integration is performed along the boundary of the finite elements or smoothing cells and no isoparametric mapping is required, which allows elements of arbitrary shape. We present numerical results for cracks in linear elastic fracture mechanics problems. The method is verified on several examples and comparisons are made to the conventional XFEM. © 2008 Civil-Comp Press. [less ▲]

Detailed reference viewed: 140 (1 UL)
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See detailA smoothed finite element method for plate analysis
Nguyen-Xuan, H.; Rabczuk, T.; Bordas, Stéphane UL et al

in Computer Methods in Applied Mechanics & Engineering (2008), 197(13-16), 1184-1203

A quadrilateral element with smoothed curvatures for Mindlin-Reissner plates is proposed. The curvature at each point is obtained by a non-local approximation via a smoothing function. The bending ... [more ▼]

A quadrilateral element with smoothed curvatures for Mindlin-Reissner plates is proposed. The curvature at each point is obtained by a non-local approximation via a smoothing function. The bending stiffness matrix is calculated by a boundary integral along the boundaries of the smoothing elements (smoothing cells). Numerical results show that the proposed element is robust, computational inexpensive and simultaneously very accurate and free of locking, even for very thin plates. The most promising feature of our elements is their insensitivity to mesh distortion. [less ▲]

Detailed reference viewed: 79 (1 UL)
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See detailA smoothed finite element method for shell analysis
Nguyen-Thanh, N.; Rabczuk, T.; Nguyen-Xuan, H. et al

in Computer Methods in Applied Mechanics & Engineering (2008), 198(2), 165-177

A four-node quadrilateral shell element with smoothed membrane-bending based on Mindlin-Reissner theory is proposed. The element is a combination of a plate bending and membrane element. It is based on ... [more ▼]

A four-node quadrilateral shell element with smoothed membrane-bending based on Mindlin-Reissner theory is proposed. The element is a combination of a plate bending and membrane element. It is based on mixed interpolation where the bending and membrane stiffness matrices are calculated on the boundaries of the smoothing cells while the shear terms are approximated by independent interpolation functions in natural coordinates. The proposed element is robust, computationally inexpensive and free of locking. Since the integration is done on the element boundaries for the bending and membrane terms, the element is more accurate than the MITC4 element for distorted meshes. This will be demonstrated for several numerical examples. [less ▲]

Detailed reference viewed: 90 (1 UL)
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See detailSmoothness of the density for the filter under infinite dimensional noise and unbounded observation coefficients
Florchinger, Patrick; Schiltz, Jang UL

in Martins de Carvalho, J.L. (Ed.) Proceedings of the 2nd Portuguese Conference on Automatic Control (1996)

Detailed reference viewed: 13 (0 UL)
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See detailSMRL: A Metamorphic Security Testing Tool for Web Systems
Mai, Xuan Phu UL; Göknil, Arda; Pastore, Fabrizio UL et al

in 2020 IEEE/ACM 42nd International Conference on Software Engineering (2020)

We present a metamorphic testing tool that alleviates the oracle problem in security testing. The tool enables engineers to specify metamorphic relations that capture security properties of Web systems ... [more ▼]

We present a metamorphic testing tool that alleviates the oracle problem in security testing. The tool enables engineers to specify metamorphic relations that capture security properties of Web systems. It automatically tests Web systems to detect vulnerabilities based on those relations. We provide a domain-specific language accompanied by an Eclipse editor to facilitate the specification of metamorphic relations. The tool automatically collects the input data and transforms the metamorphic relations into executable Java code in order to automatically perform security testing based on the collected data. The tool has been successfully evaluated on a commercial system and a leading open source system (Jenkins). Demo video: https://youtu.be/9kx6u9LsGxs. [less ▲]

Detailed reference viewed: 99 (12 UL)
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See detailSMT-based Checking of SOLOIST over Sparse Traces
Bersani, Marcello Maria; Bianculli, Domenico UL; Ghezzi, Carlo et al

in Proceedings of the 17th International Conference on Fundamental Approaches to Software Engineering (FASE 2014) (2014)

Detailed reference viewed: 184 (10 UL)
See detailA Snap-Shot of WWI in 140 Signs – One Year On
Herzog, Mechthild UL

E-print/Working paper (2014)

Detailed reference viewed: 50 (3 UL)
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See detailThe SNARC effect and its relationship to spatial abilities in women
Georges, Carrie UL; Hoffmann, Danielle UL; Schiltz, Christine UL

Poster (2013)

A classical demonstration of number-space associations is the so-called SNARC (Spatial Numerical Association of Response Codes) effect. It consists in faster reaction times to small/large digits with the ... [more ▼]

A classical demonstration of number-space associations is the so-called SNARC (Spatial Numerical Association of Response Codes) effect. It consists in faster reaction times to small/large digits with the left/right hand respectively. To get a better understanding of the well-documented inter-individual variability in the SNARC effect, we investigated the relationship between the classically used parity SNARC and spatial abilities, as indexed by visuo-spatial working memory capacity (WMC). The study population consisted of female university students (n=20; mean age=23.79; SD=2.50) recruited in the fields of humanities and educational sciences. Since systematic studies on the reliability of the SNARC effect are still lacking, we first measured the internal consistency, as assessed by split-half reliability, as well as test-retest reliability of the parity SNARC. Split-half and test-retest correlation coefficients were (r(19)=0.41; p<0.05) and (r(19)=0.25; p=0.14) respectively, indicating a trend towards consistency. In the present female population, a significant negative correlation was revealed between the strength of the parity SNARC effect (mean slope=-10.04; SD=8.66) and visuo-spatial WMC (mean WMC=2.85; SD=1.12; r(19)=-0.51; p<0.05). This finding thus indicates that number-space associations as measured by the parity SNARC effect tend to be stronger in young female adults with higher spatial abilities. [less ▲]

Detailed reference viewed: 178 (14 UL)
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See detailThe SNARC effect – Does it depend on the level of mathematical training?
Hoffmann, Danielle UL; Mussolin, Christophe; Schiltz, Christine UL

Scientific Conference (2012, February 10)

Detailed reference viewed: 19 (2 UL)
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See detailThe SNARC effect – Does it depend on the level of mathematical training?
Hoffmann, Danielle UL; Mussolin, Christophe; Schiltz, Christine UL

Poster (2011)

Behavioural studies show a relation between numbers and space (DeHevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect, consisting in faster ... [more ▼]

Behavioural studies show a relation between numbers and space (DeHevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect, consisting in faster reaction times responding to small/large digits with the left/right hand respectively (Dehaene et al. 1993). The SNARC effect has often been replicated, but it is also characterized by high inter-subject variability (Wood et al. 2006a,b). Although differences in mathematical skills are an obvious candidate source for SNARC variability, this variable has not yet been explored systematically. While in their seminal study Dehaene and colleagues had included two groups of participants differing in their field of study (science vs. literature), the differences in SNARC effect strengths indicated by the result figures were not tested formally (see also Fischer and Rottmann (2005)). The present study aims to assess the influence of mathematical training, as instantiated by the enrollment in study fields characterized by distinct levels of mathematical requirements, on the SNARC effect. We only included students of either a subject with a strong mathematical focus (e.g. mathematics, computer sciences), or no mathematical requirements at all (e.g. literature, philosophy). Results (N=36; 18/group) yielded a significant overall SNARC effect, i.e. interaction between digit magnitude and response side [F(1,35)=9.51; p=0.004], but no influence of study group on this interaction [F(1,35)=0.92; p=0.345]. Interestingly though, including gender in the ANOVA yielded a significant four-way interaction [F(1,35)=6.34; p=0.017]. These results replicate previous findings in children (Schweiter et al. 2005), interpreted as gender-related differences in mental strategy use. [less ▲]

Detailed reference viewed: 56 (1 UL)
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See detailThe Snippet Platform Architecture: Dynamic and Interactive Compound Documents
Kirsch, Laurent UL; Botev, Jean UL; Rothkugel, Steffen UL

in International Journal of Future Computer and Communication (2013), 3(3), 7

Detailed reference viewed: 119 (21 UL)
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See detailThe Snippet System - Fine-Granular Management of Documents and Their Relationships
Kirsch, Laurent UL; Esch, Markus; Rothkugel, Steffen UL

in Proceedings of the 6th International IASTED Conference on Human Computer Interaction (HCI) (2011)

In this paper the concept of the Snippet System is presented. By breaking up the rigid and inflexible way today’s operating systems store data in files and hierarchical folder structures, the Snippet ... [more ▼]

In this paper the concept of the Snippet System is presented. By breaking up the rigid and inflexible way today’s operating systems store data in files and hierarchical folder structures, the Snippet System is able to provide efficient data handling and organization facilities. Semantic relationships are used for the identification, retrieval and display of related data in a context-sensitive fashion. The entire approach is supported by novel graphical user interface elements fostering intuitive interaction. Consequently, user experience is improved by reducing the cognitive load of information management considerably. [less ▲]

Detailed reference viewed: 86 (9 UL)
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See detailThe Snippet System - Reusing and Connecting Documents
Kirsch, Laurent UL; Botev, Jean UL; Rothkugel, Steffen UL

in Proceedings of the 7th International Conference on Digital Information Management (ICDIM) (2012)

Detailed reference viewed: 34 (9 UL)
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See detailSnippets and Component-Based Authoring Tools for Reusing and Connecting Documents
Kirsch, Laurent UL; Botev, Jean UL; Rothkugel, Steffen UL

in Journal of Digital Information Management (2012), 10(6), 399-409

Detailed reference viewed: 76 (12 UL)