Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailUnderstanding dynamics using sensitivity analysis: caveat and solution
Perumal, Thanneer Malai UL; Gunawan, Rudiyanto

in BMC Systems Biology (2011), 5

BACKGROUND: Parametric sensitivity analysis (PSA) has become one of the most commonly used tools in computational systems biology, in which the sensitivity coefficients are used to study the parametric ... [more ▼]

BACKGROUND: Parametric sensitivity analysis (PSA) has become one of the most commonly used tools in computational systems biology, in which the sensitivity coefficients are used to study the parametric dependence of biological models. As many of these models describe dynamical behaviour of biological systems, the PSA has subsequently been used to elucidate important cellular processes that regulate this dynamics. However, in this paper, we show that the PSA coefficients are not suitable in inferring the mechanisms by which dynamical behaviour arises and in fact it can even lead to incorrect conclusions. RESULTS: A careful interpretation of parametric perturbations used in the PSA is presented here to explain the issue of using this analysis in inferring dynamics. In short, the PSA coefficients quantify the integrated change in the system behaviour due to persistent parametric perturbations, and thus the dynamical information of when a parameter perturbation matters is lost. To get around this issue, we present a new sensitivity analysis based on impulse perturbations on system parameters, which is named impulse parametric sensitivity analysis (iPSA). The inability of PSA and the efficacy of iPSA in revealing mechanistic information of a dynamical system are illustrated using two examples involving switch activation. CONCLUSIONS: The interpretation of the PSA coefficients of dynamical systems should take into account the persistent nature of parametric perturbations involved in the derivation of this analysis. The application of PSA to identify the controlling mechanism of dynamical behaviour can be misleading. By using impulse perturbations, introduced at different times, the iPSA provides the necessary information to understand how dynamics is achieved, i.e. which parameters are essential and when they become important. [less ▲]

Detailed reference viewed: 38 (0 UL)
Full Text
See detailUnderstanding human need fulfilment to support the design of secure experiences
Distler, Verena UL

in Proceedings of NordiCHI' 18 Doctoral Consortium (2018)

Detailed reference viewed: 30 (11 UL)
Full Text
Peer Reviewed
See detailUnderstanding the differences between how novice and experienced designers approach design tasks
Ahmed, S.; Wallace, K. M.; Blessing, Lucienne UL

in Research in Engineering Design (2003), 14(1), 1-11

Research was undertaken to understand how to provide the most appropriate support for novice designers in engineering design. However, how designers apply their experience and knowledge is not understood ... [more ▼]

Research was undertaken to understand how to provide the most appropriate support for novice designers in engineering design. However, how designers apply their experience and knowledge is not understood and further research in this area is required. This paper describes an observational study to understand how novice and experienced designers approach design tasks. [less ▲]

Detailed reference viewed: 88 (0 UL)
Full Text
Peer Reviewed
See detailUndesirable Consequences and Social Contexts of Technology Use: A Micro-analysis of Embodied User Interaction
Jungmann, Manuela UL; Cox, Richard

in Interacting with Computers (2017), 29(4), 481493

The focus of this paper is on the unexpected and undesirable consequences of social interaction with technological innovations, which we analyse with the support of two frameworks to better comprehend ... [more ▼]

The focus of this paper is on the unexpected and undesirable consequences of social interaction with technological innovations, which we analyse with the support of two frameworks to better comprehend their social implications. The first, techno-social framework, consists of Allenby and Sarewitz's taxonomy of technological social function. In the second, cognitive, framework, we introduce concepts from dual-systems theory. The frameworks provide a lens through which to view techno-cultural examples. This sets the stage for our case study in which we investigate an interactive game installation. Using data analytics, we uncover hidden effects due to the social interactions between the players and to their physical attributes. We conclude that there is a pressing need for innovators to broaden the scope of their evaluations to not just evaluate innovative technologies at the initial engineering/design phase but also to conduct evaluations at later phases of adoption and appropriation that focus on social contexts-of-use. [less ▲]

Detailed reference viewed: 59 (3 UL)
Full Text
Peer Reviewed
See detailUniversal health coverage: an urgent need for collaborative learning and technology in primary care
Patel, Kunal D.; Mcloughlin, Clodagh; Lygidakis, Charilaos UL et al

in Education for Primary Care (2017)

Universal health coverage is an achievable goal for all health professionals globally. However, for it to be implemented technology and collaboration are essential. This letter focuses on recently ... [more ▼]

Universal health coverage is an achievable goal for all health professionals globally. However, for it to be implemented technology and collaboration are essential. This letter focuses on recently published recommendations for technology in primary care education in respect to Universal Health Coverage. [less ▲]

Detailed reference viewed: 71 (2 UL)
Full Text
Peer Reviewed
See detailUnpacking Collaboration in Digital History Projects
Kemman, Max UL

Scientific Conference (2017)

Detailed reference viewed: 56 (8 UL)
Full Text
Peer Reviewed
See detailUntersuchungen der instationären Strömungstopologie im Nachlauf einer Seehundvibrisse.
Witte, Matthias; Michael, Mark UL; Brede, Martin et al

in Delgado, A.; Rauh, A.; Lienhart, H. (Eds.) et al Proceedings der 17.GALA-Fachtagung “Lasermethoden in der Strömungsmesstechnik“ (2009)

Die Vibrissen von Seehunden zeichnen sich durch eine komplizierte dreidimensionale Struk- turierung aus. Sie versetzen den Seehund in die Lage, hydrodynamische Nachlaufspuren von Beutefischen zu ... [more ▼]

Die Vibrissen von Seehunden zeichnen sich durch eine komplizierte dreidimensionale Struk- turierung aus. Sie versetzen den Seehund in die Lage, hydrodynamische Nachlaufspuren von Beutefischen zu detektieren. Mit Hilfe von Stereo- μ Piv Messungen an Seehundvibrissen konnte die stationäre Strömungstopologie des Vibrissennachlaufes ermittelt werden. Zum besseren Verständnis der Funktion der Vibrissenstrukturierung ist es notwendig, die instatio- näre Strömungstopologie zu kennen. Durch räumlich und zeitlich hochauflösende numeri- sche Verfahren konnte die instationäre Strömungstopologie im Nachlauf einer Seehund- vibrisse ermittelt werden. [less ▲]

Detailed reference viewed: 50 (1 UL)
Full Text
Peer Reviewed
See detailUsage of Smartphone Data to Derive an Indicator for Collaborative Mobility between Individuals
Toader, Bogdan UL; Sprumont, François UL; Faye, Sébastien UL et al

in ISPRS International Journal of Geo-Information (2017), 6(3), 62

The potential of geospatial big data has been drawing attention for a few years. Despite the larger and larger market penetration of portable technologies (nomadic and wearable devices like smartphones ... [more ▼]

The potential of geospatial big data has been drawing attention for a few years. Despite the larger and larger market penetration of portable technologies (nomadic and wearable devices like smartphones and smartwatches), their opportunities for travel behavior analysis are still relatively unexplored. The main objective of our study is to extract the human mobility patterns from GPS traces in order to derive an indicator for enhancing Collaborative Mobility (CM) between individuals. The first step, extracting activity duration and location, is done using state-of-the-art automated recognition tools. Sensors data are used to reconstruct individual’s activity location and duration across time. For constructing the indicator, in a second step, we defined different variables and methods for specific case studies. Smartphone sensor data are being collected from a limited number of individuals and for one week. These data are used to evaluate the proposed indicator. Based on the value of the indicator, we analyzed the potential for identifying CM among groups of users, such as sharing traveling resources (e.g., carpooling, ridesharing, parking sharing) and time (rescheduling and reordering activities). [less ▲]

Detailed reference viewed: 176 (17 UL)
Full Text
See detailUse of commercial simulation software for analyzing the dynamics of an injection-molding clamp unit
Hostert, Claude UL

Doctoral thesis (2006)

Today, the interest in integrated dynamic analysis of mechatronic systems increases. Different approaches are possible depending on the nature of the system, on the required complexity of the model, or ... [more ▼]

Today, the interest in integrated dynamic analysis of mechatronic systems increases. Different approaches are possible depending on the nature of the system, on the required complexity of the model, or simply on the tools available to the engineer. During this work, the aim was to implement specialized commercial simulation software packages and to combine them in order to simulate the dynamic behavior of mechatronic systems as for example an injection molding machine. The multi-body simulation software is the backbone of the current analysis as it inherently models large non-linear motions. It is possible to account for the flexibility of components in the MBS model if necessary. Furthermore, other simulation codes were used to model the hydraulic and controls systems. The case studies show the interest and the potential of a combined analysis of mechatronic systems. Once the different sub-models, generated with the adequate simulation tool, have been successfully linked and validated by measurements, various scenarios can be simulated and analyzed. The model provides the engineer with an additional insight into the overall system and thus with a better understanding of its dynamic characteristics. The interactions between the subsystems, which may be of very distinctive nature, can be investigated. Generally, it is difficult to predict such relations intuitively. Finally, the model allows to simulate with different design parameters and to asses the effect of modifications to these on the overall performance of the machine. This helps to identify the significant parameters that are crucial for an optimized functioning. [less ▲]

Detailed reference viewed: 215 (5 UL)
Full Text
See detailUsing Bayes' theorem to infer the material parameters of human soft tissue
Hale, Jack UL; Farrell, Patrick; Bordas, Stéphane UL

Presentation (2015, October 21)

Detailed reference viewed: 107 (5 UL)
Full Text
See detailUsing Bayesian inference to recover the material parameters of a heterogeneous hyperelastic body
Hale, Jack UL; Farrell, Patrick; Bordas, Stéphane UL

Scientific Conference (2016)

We present a method for calculating a Bayesian uncertainty estimate on the recovered material parameters of a heterogeneous geometrically non-linear hyperelastic body. We formulate the problem in the ... [more ▼]

We present a method for calculating a Bayesian uncertainty estimate on the recovered material parameters of a heterogeneous geometrically non-linear hyperelastic body. We formulate the problem in the Bayesian inference framework [1]; given noisy and sparse observations of a body, some prior knowledge on the parameters and a parameter-to-observable map the goal is to recover the posterior distribution of the parameters given the observations. In this work we primarily focus on the challenges of developing dimension-independent algorithms in the context of very large inverse problems (tens to hundreds of thousands of parameters). Critical to the success of the method is viewing the problem in the correct infinite- dimensional function space setting [2]. With this goal in mind, we show the use of automatic symbolic differentiation techniques to construct high-order adjoint models [3], scalable maximum a posteriori (MAP) estimators, and efficient low-rank update methods to calculate credible regions on the posterior distribution [4]. [less ▲]

Detailed reference viewed: 113 (14 UL)
Full Text
Peer Reviewed
See detailUsing Complex Problem Solving Simulations for General Cognitive Ability Assessment: the Genetics Lab Framework
Mayer, Hélène; Hazotte, Cyril; Djaghloul, Younes et al

in International Journal of Information Science and Intelligent System (2013), 2(4), 71-88

This paper presents the conception and operation of “the Genetics Lab,” a research platform designed for general intelligence measurement. This tool has been developed and refined to measure cognitive ... [more ▼]

This paper presents the conception and operation of “the Genetics Lab,” a research platform designed for general intelligence measurement. This tool has been developed and refined to measure cognitive skills of students in Luxembourg, Thanks to its generic and clear architecture, “the Genetics Lab” makes a major contribution by addressing technical weaknesses and flaws met with tools previously used to assess intelligence. This new platform can be used as groundwork for other evaluation solutions. In this paper, we explore in depth the main fields of e-assessment such as instructions, localized and multilingual content production and display, traces, and scoring. We also describe how the platform was put into action to create complex simulations and to make data collection resulting from the user’s test a flawless process. This paper is a continuation and extension of earlier work. [less ▲]

Detailed reference viewed: 106 (11 UL)
Full Text
Peer Reviewed
See detailUsing mobile phone data for urban network state estimation
Derrmann, Thierry; Frank, Raphaël UL; Engel, Thomas UL et al

Scientific Conference (2018, June)

Detailed reference viewed: 39 (3 UL)
Full Text
Peer Reviewed
See detailA UX Approach to Privacy and Security: the Impact of User, Contextual and System-Related Factors
Distler, Verena UL; Lallemand, Carine UL; Koenig, Vincent UL

in CHI Workshop Exploring Individual Diffferences in Privacy (2018, April)

This position paper lays out current and future studies which we conduct on the UX aspects of security and privacy, our goal being to understand which factors influence privacy-related decision-making. We ... [more ▼]

This position paper lays out current and future studies which we conduct on the UX aspects of security and privacy, our goal being to understand which factors influence privacy-related decision-making. We advocate using UX design methods in order to study interindividual differences, system-related and contextual factors involved in privacy and security attitudes and behaviors. These results will contribute to user-tailored and personalized privacy initiatives and guide the design of future technologies. [less ▲]

Detailed reference viewed: 176 (12 UL)
Full Text
Peer Reviewed
See detailA UX Approach to Privacy and Security: the Impact of User, Contextual and System-Related Factors
Distler, Verena UL; Lallemand, Carine UL; Koenig, Vincent UL

in CHI Workshop Exploring Individual Diffferences in Privacy (2018, April)

This position paper lays out current and future studies which we conduct on the UX aspects of security and privacy, our goal being to understand which factors influence privacy-related decision-making. We ... [more ▼]

This position paper lays out current and future studies which we conduct on the UX aspects of security and privacy, our goal being to understand which factors influence privacy-related decision-making. We advocate using UX design methods in order to study interindividual differences, system-related and contextual factors involved in privacy and security attitudes and behaviors. These results will contribute to user-tailored and personalized privacy initiatives and guide the design of future technologies. [less ▲]

Detailed reference viewed: 176 (12 UL)
Full Text
Peer Reviewed
See detailA variational formulation of dissipative quasicontinuum methods
Rokos, Ondrej; Beex, Lars UL; Peerlings, Ron et al

in International Journal of Solids and Structures (2016), 102-103

Lattice systems and discrete networks with dissipative interactions are successfully employed as meso-scale models of heterogeneous solids. As the application scale generally is much larger than that of ... [more ▼]

Lattice systems and discrete networks with dissipative interactions are successfully employed as meso-scale models of heterogeneous solids. As the application scale generally is much larger than that of the discrete links, physically relevant simulations are computationally expensive. The QuasiContinuum (QC) method is a multiscale approach that reduces the computational cost of direct numerical simulations by fully resolving complex phenomena only in regions of interest while coarsening elsewhere. In previous work (Beex et al., J. Mech. Phys. Solids 64, 154-169, 2014), the originally conservative QC methodology was generalized to a virtual-power-based QC approach that includes local dissipative mechanisms. In this contribution, the virtual-power-based QC method is reformulated from a variational point of view, by employing the energy-based variational framework for rate-independent processes (Mielke and Roub cek, Rate-Independent Systems: Theory and Application, Springer-Verlag, 2015). By construction it is shown that the QC method with dissipative interactions can be expressed as a minimization problem of a properly built energy potential, providing solutions equivalent to those of the virtual-power-based QC formulation. The theoretical considerations are demonstrated on three simple examples. For them we verify energy consistency, quantify relative errors in energies, and discuss errors in internal variables obtained for different meshes and two summation rules. [less ▲]

Detailed reference viewed: 97 (8 UL)
Full Text
Peer Reviewed
See detailVibration of functionally graded material plates with cutouts & cracks in thermal environment
Rahimabadi, A. A.; Natarajan, S.; Bordas, Stéphane UL

in Key Engineering Materials (2013), 560

In this paper, the effect of a centrally located cutout (circular and elliptical) and cracks emanating from the cutout on the free flexural vibration behaviour of functionally graded material plates in ... [more ▼]

In this paper, the effect of a centrally located cutout (circular and elliptical) and cracks emanating from the cutout on the free flexural vibration behaviour of functionally graded material plates in thermal environment is studied. The discontinuity surface is represented independent of the mesh by exploiting the partition of unity method framework. A Heaviside function is used to capture the jump in the displacement across the discontinuity surface and asymptotic branch functions are used to capture the singularity around the crack tip. An enriched shear flexible 4-noded quadrilateral element is used for the spatial discretization. The properties are assumed to vary only in the thickness direction. The effective properties of the functionally graded material are estimated using the Mori-Tanaka homogenization scheme and the plate kinematics is based on the first order shear deformation theory. The influence of the plate geometry, the geometry of the cutout, the crack length, the thermal gradient and the boundary conditions on the free flexural vibration is numerically studied. © (2013) Trans Tech Publications, Switzerland. [less ▲]

Detailed reference viewed: 246 (5 UL)
Full Text
See detailVicinity Resource Cartography for Delay-Tolerant Networks: a Holistic Perspective
Sandulescu, Gabriel UL; Schaffer, Peter UL; Nadjm-Tehrani, Simin UL

in 2010 IFIP W IRELESS D AYS (2010)

In this paper we propose a distributed algorithm allowing nodes in delay-tolerant networks to construct vicinity resource maps based on past encounters. Our algorithm estimates the availability of the ... [more ▼]

In this paper we propose a distributed algorithm allowing nodes in delay-tolerant networks to construct vicinity resource maps based on past encounters. Our algorithm estimates the availability of the following resources: energy, buffer space, and bandwidth. We then show how a store-carry-forward scheme may benefit from having access to these resource estimates. While knowledge about resources available in the vicinity allows nodes to implement meaningful custodian election strategies, an evaluation of available bandwidth and contact time allows them to carry out adaptive queue management strategies. Thus, such strategies can be approached from a holistic perspective based on the availability of the three resources under consideration in node proximity.We validate our model separately in time-varying and space-varying environments. In addition to synthetic mobility models (random waypoint) we validate our resource estimation in a disaster area mobility model (using Bonn motion traces). We show that by using this information a routing protocol may dramatically improve its delivery rate and energy overhead while keeping delivery latency almost constant. [less ▲]

Detailed reference viewed: 54 (0 UL)
Full Text
Peer Reviewed
See detailVirtual and smoothed finite elements: A connection and its application to polygonal/polyhedral finite element methods
Natarajan, Sundararajan; Bordas, Stéphane UL; Ooi, Ean Tat

in International Journal for Numerical Methods in Engineering (2015), 104(13), 1173-1199

We show both theoretically and numerically a connection between the smoothed finite element method (SFEM) and the virtual element method and use this approach to derive stable, cheap and optimally ... [more ▼]

We show both theoretically and numerically a connection between the smoothed finite element method (SFEM) and the virtual element method and use this approach to derive stable, cheap and optimally convergent polyhedral FEM.We show that the stiffness matrix computed with one subcell SFEM is identical to the consistency term of the virtual element method, irrespective of the topology of the element, as long as the shape functions vary linearly on the boundary. Using this connection, we propose a new stable approach to strain smoothing for polygonal/polyhedral elements where, instead of using sub-triangulations, we are able to use one single polygonal/polyhedral subcell for each element while maintaining stability. For a similar number of degrees of freedom, the proposed approach is more accurate than the conventional SFEM with triangular subcells. The time to compute the stiffness matrix scales with the O.dof s/1:1 in case of the conventional polygonal FEM, while it scales as O.dof s/0:7 in the proposed approach. The accuracy and the convergence properties of the SFEM are studied with a few benchmark problems in 2D and 3D linear elasticity. [less ▲]

Detailed reference viewed: 64 (1 UL)
See detailVirtual Coach Reaches Out To Me
Aleksic, Gabrijela UL

Conference given outside the academic context (2013)

Detailed reference viewed: 5 (1 UL)