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See detailCorotational cut finite element method for real-time surgical simulation: Application to needle insertion simulation
Bui, Huu Phuoc UL; Tomar, Satyendra UL; Bordas, Stéphane UL

in Computer Methods in Applied Mechanics and Engineering (2018), 345

We present the corotational cut Finite Element Method (FEM) for real-time surgical simulation. The only requirement of the proposed method is a background mesh, which is not necessarily conforming to the ... [more ▼]

We present the corotational cut Finite Element Method (FEM) for real-time surgical simulation. The only requirement of the proposed method is a background mesh, which is not necessarily conforming to the boundaries/interfaces of the simulated object. The details of the surface, which can be directly obtained from binary images, are taken into account by a multilevel embedding algorithm which is applied to elements of the background mesh that are cut by the surface. Dirichlet boundary conditions can be implicitly imposed on the surface using Lagrange multipliers, whereas traction or Neumann boundary conditions, which is/are applied on parts of the surface, can be distributed to the background nodes using shape functions. The implementation is verified by convergences studies, of the geometry and of numerical solutions, which exhibit optimal rates. To verify the reliability of the method, it is applied to various needle insertion simulations (e.g. for biopsy or brachytherapy) into brain and liver models. The numerical results show that, while retaining the accuracy of the standard FEM, the proposed method can (1) make the discretisation independent from geometric description, (2) avoid the complexity of mesh generation for complex geometries, and (3) provide computational speed suitable for real-time simulations. Thereby, the proposed method is very suitable for patient-specific simulations as it improves the simulation accuracy by automatically, and properly, taking the simulated geometry into account, while keeping the low computational cost. [less ▲]

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See detailCorrect biological timing in Arabidopsis requires multiple light-signaling pathways.
Dalchau, N.; Hubbard, K. E.; Robertson, F. C. et al

in Proceedings of the National Academy of Sciences of the United States of America (2010), 107(29), 13171-13176

Circadian oscillators provide rhythmic temporal cues for a range of biological processes in plants and animals, enabling anticipation of the day/night cycle and enhancing fitness-associated traits. We ... [more ▼]

Circadian oscillators provide rhythmic temporal cues for a range of biological processes in plants and animals, enabling anticipation of the day/night cycle and enhancing fitness-associated traits. We have used engineering models to understand the control principles of a plant's response to seasonal variation. We show that the seasonal changes in the timing of circadian outputs require light regulation via feed-forward loops, combining rapid light-signaling pathways with entrained circadian oscillators. Linear time-invariant models of circadian rhythms were computed for 3,503 circadian-regulated genes and for the concentration of cytosolic-free calcium to quantify the magnitude and timing of regulation by circadian oscillators and light-signaling pathways. Bioinformatic and experimental analysis show that rapid light-induced regulation of circadian outputs is associated with seasonal rephasing of the output rhythm. We identify that external coincidence is required for rephasing of multiple output rhythms, and is therefore important in general phase control in addition to specific photoperiod-dependent processes such as flowering and hypocotyl elongation. Our findings uncover a fundamental design principle of circadian regulation, and identify the importance of rapid light-signaling pathways in temporal control. [less ▲]

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See detailA cost-effective atomic force microscope for undergraduate control laboratories
Jones, C. N.; Goncalves, Jorge UL

in IEEE Transactions on Education (2010), 53(2), 328-334

This paper presents a simple, cost-effective and robust atomic force microscope (AFM), which has been purposely designed and built for use as a teaching aid in undergraduate controls labs. The guiding ... [more ▼]

This paper presents a simple, cost-effective and robust atomic force microscope (AFM), which has been purposely designed and built for use as a teaching aid in undergraduate controls labs. The guiding design principle is to have all components be open and visible to the students, so the inner functioning of the microscope has been made clear to see. All of the parts but one are off the shelf, and assembly time is generally less than two days, which makes the microscope a robust instrument that is readily handled by the students with little chance of damage. While the scanning resolution is nowhere near that of a commercial instrument, it is more than sufficient to take interesting scans of micrometer-scale objects. A survey of students after their having used the AFM resulted in a generally good response, with 80% agreeing that they had a positive learning experience. [less ▲]

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See detailCoupled molecular-dynamics and finite-element-method simulations for the kinetics of particles subjected to field-mediated forces
Cascio, Michele; Baroli, Davide UL; Bordas, Stéphane UL et al

in Physical Review. E ,Statistical, Nonlinear, and Soft Matter Physics (2019), 99(6),

A computational approach that couples molecular-dynamics (MD) and the-finite-element-method (FEM) technique is here proposed for the theoretical study of the dynamics of particles subjected to ... [more ▼]

A computational approach that couples molecular-dynamics (MD) and the-finite-element-method (FEM) technique is here proposed for the theoretical study of the dynamics of particles subjected to electromechanical forces. The system consists of spherical particles (modeled as micrometric rigid bodies with proper densities and dielectric functions) suspended in a colloidal solution, which flows in a microfluidic channel in the presence of a generic nonuniform variable electric field generated by electrodes. The particles are subjected to external forces (e.g., drag or gravity) which satisfy a particlelike formulation that is typical of the MD approach, along with an electromechanical force that, in turn, requires the three-dimensional self-consistent solutions of correct continuum field equations during the integration of the equations of motion. In the MD-FEM method used in this work, the finite element method is applied to solve the continuum field equations while the MD technique is used for the stepwise explicit integration of the equations of motion. Our work shows the potential of coupled MD-FEM simulations for the study of electromechanical particles and opens a double perspective for implementing (a) MD away from the field of atomistic simulations and (b) the continuum-particle approach to cases where the conventional force evaluation used in MD is not applicable. [less ▲]

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See detailCrack growth calculations in solder joints based on microstructural phenomena with X-FEM
Menk, Alexander; Bordas, Stéphane UL

in Computational Materials Science (2011), 50(3), 1145-1156

Determining the lifetime of solder joints subjected to thermomechanical loads is crucial to guarantee the quality of electronic devices. The fatigue process is heavily dependent on the microstructure of ... [more ▼]

Determining the lifetime of solder joints subjected to thermomechanical loads is crucial to guarantee the quality of electronic devices. The fatigue process is heavily dependent on the microstructure of the joints. We present a new methodology to determine the lifetime of the joints based on microstructural phenomena. Random microstructures are generated to capture the statistical variety of possible microstructures and crack growth calculations are performed. The extended finite element method is used to solve the structural problem numerically which allows a complete automation of the process. Numerical examples are given and compared to experimental data. [less ▲]

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See detailCrafting Conversational Agents' Personality in a User-Centric Context
Mano Ferreira, Cátia; Höhn, Sviatlana UL

in Proceedings of the 31st Benelux Conference on Artificial Intelligence (BNAIC 2019) and the 28th Belgian Dutch Conference on Machine Learning (Benelearn 2019) (2019, November)

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See detailCREATIVITY IN TRANSACTIONAL DESIGN PROBLEMS: NON-INTUITIVE FINDINGS OF AN EXPERT STUDY USING SCAMPER
Moreno Grandas, Diana Paola UL; Yang, Maria C.; Hernandez, Alberto A. et al

in INTERNATIONAL DESIGN CONFERENCE - DESIGN 2014 (2014, May)

Designers are currently facing design problems that are not uniquely related to physical systems but transactional as well. Transactional processes (services) have had a steady growth during the last ... [more ▼]

Designers are currently facing design problems that are not uniquely related to physical systems but transactional as well. Transactional processes (services) have had a steady growth during the last three decades and currently add more than 65% of global economic value. This study expands our understanding of designers’ interaction with ideation methods. We investigate a heuristic method known as SCAMPER, focusing on a transactional design problem with a relatively large transactional domain expert sample size (n=60). The study shows, unexpectedly, that the SCAMPER method appears to be both a fixating and de-fixating method (at least for the type of problem explored), where design fixation is not shown to be effectively mitigated by the method; yet, despite this finding, a significantly higher novelty production is achieved when compared to a non-assisted scenario. [less ▲]

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See detailCross-enterprise value stream assessment
Oberhausen, Christof UL; Plapper, Peter UL

in Journal of Advances in Management Research (2017), 14(2), 182-193

Purpose – In most cases, the conventional assessment of value streams is based on key performance indicators (KPIs) like the share of added value, the degree of flow or a comprehensive lead time analysis ... [more ▼]

Purpose – In most cases, the conventional assessment of value streams is based on key performance indicators (KPIs) like the share of added value, the degree of flow or a comprehensive lead time analysis. To evaluate cross-enterprise value streams of manufacturing, business or service processes in detail, a holistic methodology is needed. The paper aims to discuss this issue. Design/methodology/approach – In this research paper, the assessment of value streams within complex cross-company networks is described. After a presentation of relevant KPIs in the fields of value stream management (VSM) and supply chain management (SCM), an approach for a cross-enterprise evaluation of value streams on different levels of detail is shown. In addition, the use of an absolute VSM evaluation, in contrast to a relative VSM assessment, is examined. Findings – Based on a uniform and well-balanced set of KPIs and other VSM and SCM parameters, a performance assessment on different levels of value stream detail is enabled. Further investigations reveal the advantages of a relative compared with an absolute VSM assessment. Research limitations/implications – In addition to a comprehensive overview of existing KPIs for a value stream assessment beyond company borders, a holistic and multi-level VSM approach is presented in this paper. In contrast to existing VSM approaches, the described method allows an evaluation and subsequent improvement of value streams within supply chain networks. Up to now, the presented approach for the assessment of cross-enterprise value streams has only been tested in specific industrial environments. In future, the proposed methodology shall also be validated for other process types like business, service or further manufacturing processes. Practical implications – The described cross-company performance measurement approach shows a high practical relevance for organizations operating in supply chain networks. Due to the integrated use of different VSM parameters, the evaluation of highly interconnected value streams across corporate boundaries is facilitated. By means of a case study, the proposed methodology is validated under real industry conditions and proves its practical applicability. Originality/value – One of the novel features of this research is the extension of the traditional VSM method with respect to a relative evaluation of value streams based on a set of significant KPIs. In addition, the allocation of these KPIs to different value stream layers and categories leads to an innovative approach for a multi-level assessment according to the needs of the specific VSM application, e.g. a more standardized use of VSM in complex supply chain networks. [less ▲]

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See detailCutting in real time in corotational elasticity and perspectives on simulating cuts
Courtecuisse, H.; Kerfriden, P.; Bordas, Stéphane UL

Book published by Springer (2013)

We focus here on the simulation of surgical acts of types similar to cutting and needle insertion in soft tissue, in real time (500 Hz), where the scale of the surgical instrument is several orders of ... [more ▼]

We focus here on the simulation of surgical acts of types similar to cutting and needle insertion in soft tissue, in real time (500 Hz), where the scale of the surgical instrument is several orders of magnitude smaller than that of the organ. [less ▲]

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See detailCyber Security and Vulnerability Analysis of Networked Control System subject to False-Data injection
Gerard, Benjamin; Bezzaoucha, Souad UL; Voos, Holger UL et al

in Proceedings of the 2018 American Control Conference (2018, June 27)

In the present paper, the problem of networked control system (NCS) cyber security is considered. The geometric approach is used to evaluate the security and vulnerability level of the controlled system ... [more ▼]

In the present paper, the problem of networked control system (NCS) cyber security is considered. The geometric approach is used to evaluate the security and vulnerability level of the controlled system. The proposed results are about the so-called false data injection attacks and show how imperfectly known disturbances can be used to perform undetectable, or at least stealthy, attacks that can make the NCS vulnerable to attacks from malicious outsiders. A numerical example is given to illustrate the approach. [less ▲]

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See detailCybermenaces, enjeux et sécurité : entretien avec Stéphane Bortzmeyer et Mohsen Souissi (Afnic)
Schafer, Valerie UL

in Flux: Cahiers Scientifiques Internationaux Réseaux et Territoires (2020), 2019/4

Si les cyberattaques récentes au Moyen-Orient, menées via les noms de domaine, ont eu un vaste écho médiatique fin février 2019, tandis que la revue Défense et Sécurité Internationale consacrait un ... [more ▼]

Si les cyberattaques récentes au Moyen-Orient, menées via les noms de domaine, ont eu un vaste écho médiatique fin février 2019, tandis que la revue Défense et Sécurité Internationale consacrait un dossier spécial à la techno-guérilla, les menaces qui pèsent sur les réseaux informatiques ne sont pas nouvelles. L’Afnic – Association Française pour le Nommage Internet en Coopération –, gestionnaire historique du .fr, fait partie des acteurs français confrontés au quotidien aux enjeux de sécurité des réseaux Internet et veille notamment à la sécurité des noms de domaine et au bon fonctionnement du .fr, en terme de disponibilité mais aussi d’intégrité. Mohsen Souissi, alors Responsable des Sécurité des Sys- tèmes d’information (RSSI) à l’Afnic, qu’il a intégrée en 2000 et où il était précédemment responsable Recherche et développement (R&D) de 2007 à 2016, et Stéphane Bortzmeyer, auteur de Cyberstructure (C&F Éditions, 2018) et ingénieur à l’Afnic depuis seize ans, après avoir été administrateur pour plusieurs systèmes et réseaux universitaires et de centres de recherche, reviennent sur les cybermenaces et les enjeux de sécurité auxquels ils sont confrontés. [less ▲]

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See detailData Centric Engineering and Data-Driven Modelling - Computational Engineering Lab Report 2019
Bordas, Stéphane UL; Peters, Bernhard UL; Viti, Francesco UL et al

Report (2019)

https://www.cambridge.org/core/journals/data-centric-engineering

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See detailData driven discovery of cyber physical systems
Yuan, Ye; Tang, Xiuchuan; Zhou, Wei et al

in Nature Communications (2019)

Cyber-physical systems embed software into the physical world. They appear in a wide range of applications such as smart grids, robotics, and intelligent manufacturing. Cyber-physical systems have proved ... [more ▼]

Cyber-physical systems embed software into the physical world. They appear in a wide range of applications such as smart grids, robotics, and intelligent manufacturing. Cyber-physical systems have proved resistant to modeling due to their intrinsic complexity arising from the combination of physical and cyber components and the interaction between them. This study proposes a general framework for discovering cyber-physical systems directly from data. The framework involves the identification of physical systems as well as the inference of transition logics. It has been applied successfully to a number of real-world examples. The novel framework seeks to understand the underlying mechanism of cyber-physical systems as well as make predictions concerning their state trajectories based on the discovered models. Such information has been proven essential for the assessment of the performance of cyber- physical systems; it can potentially help debug in the implementation procedure and guide the redesign to achieve the required performance. [less ▲]

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See detailDATA DRIVEN SURGICAL SIMULATIONS
Deshpande, Saurabh UL; Bordas, Stéphane UL; Beex, Lars UL et al

Scientific Conference (2020, July)

Detailed reference viewed: 35 (4 UL)
See detailData mining in geographical contexts and texts
Caruso, Geoffrey UL

Presentation (2010)

An increasing number of institutions, acting at different scales and within different sectors, create in-house geographical information systems, e.g. for regional statistics, for land and transport ... [more ▼]

An increasing number of institutions, acting at different scales and within different sectors, create in-house geographical information systems, e.g. for regional statistics, for land and transport management, for local urban planning, etc. In addition, with the advent of new technologies, such as GPS's or web-mapping facilities, the use of such geographical data is being more and more popular and data is made more easily accessible (sometimes even contributed by the end-users). Geographers find themselves in rather data rich environments today (irrespective of homogeneity and quality). Also geographical objects require specific visualization and statistical methods. The application and adaptation of data mining approaches in geographical contexts is an increasingly important research topic. In this lecture we will start from theoretical considerations on data mining in geography, particularly emphasizing what is special with exploratory spatial data analysis. We will then refer to ongoing research related to geographical data mining undertaken at the University of Luxembourg in collaboration with colleagues from other institutions. A first example will refer to a large and homogeneous dataset of all dwellings within a Belgian province. Using graph theory and local spatial statistics, the data is used to identify and categorize urbanisation patterns across scales in an iterative way. A second example will depict an application of 'self-organizing maps' to understand patterns of 'territorial cohesion' in Europe using a rather small and lacunary dataset. The third example will be dedicated to a text-mining application to a rather large corpus of documents related to spatial development in Europe. This work funded under the ESPON (European Spatial Observatory Network) aims at producing a relevant thematic structure to the online regional statistics database of the ESPON network. [less ▲]

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See detailThe DAta Protection REgulation COmpliance Model
Bartolini, Cesare UL; Lenzini, Gabriele UL; Robaldo, Livio UL

in IEEE Security and Privacy (2019), 17(6), 37-45

Understanding whether certain technical measures comply with the General Data Protection Regulation’s (GDPR’s) principles is complex legal work. This article describes a model of the GDPR that allows for ... [more ▼]

Understanding whether certain technical measures comply with the General Data Protection Regulation’s (GDPR’s) principles is complex legal work. This article describes a model of the GDPR that allows for semiautomatic processing of legal text and the leveraging of state-of-the-art legal informatics approaches, which are useful for legal reasoning, software design, information retrieval, or compliance checking. [less ▲]

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See detailData Science and Environmental Cheminformatics (SanDAL Workshop, Uni Lu)
Schymanski, Emma UL

Presentation (2020, October 13)

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See detailData Science in Europe
Flach, Peter; Spiliopoulou, Myra; Allegrezza, Serge et al

in International Journal of Data Science and Analytics (2018)

Detailed reference viewed: 50 (0 UL)