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Relying on video data, we are able to show that CA allows ... [more ▼]In a single case study, we show how a conversation analysis (CA) approach can shed light onto the sequential unfolding of human-robot interaction. Relying on video data, we are able to show that CA allows us to investigate the respective turn-taking systems of humans and a NAO robot in their dialogical dynamics, thus pointing out relevant differences. Our fine grained video analysis points out occurring breakdowns and their overcoming when humans and a NAO-robot engage in a multimodally uttered multi-party communication during a sports guessing game. Our findings suggest that interdisciplinary work opens up the opportunity to gain new insights into the challenging issues of human robot communication in order to provide resources for developing mechanisms that enable complex HRI. [less ▲]Detailed reference viewed: 190 (13 UL) Investigating the robustness of route-based sensor location policies under variable network demandRinaldi, Marco ; Viti, Francesco Scientific Conference (2019, June)Detailed reference viewed: 23 (0 UL) Isogeometric analysis of functionally graded carbon nanotube-reinforced composite plates using higher-order shear deformation theoryP., Phung-Van; M., Abdel-Wahab; K.M., Liew et alin Composite Structures (2015), 123This paper presents a simple and effective formulation based on isogeometric Analysis (IGA) and higher-order shear deformation theory (HSDT) to investigate the static and dynamic vibration behaviour of ... [more ▼]This paper presents a simple and effective formulation based on isogeometric Analysis (IGA) and higher-order shear deformation theory (HSDT) to investigate the static and dynamic vibration behaviour of functionally graded carbon nano-reinforced composite plates. The material properties of functionally graded carbon nanotube-reinforced composites (FG-CNTRCs) are assumed to be graded through the thickness direction according to several linear distributions of the volume fraction of carbon nanotubes. The governing equation is approximated according to the HSDT model using isogeometric elements based on Non-Uniform Rational B-Spline (NURBS) basis functions. This achieves naturally any desired degree of continuity through the choice of the interpolation order, so that the method easily fulfils the C1-continuity requirement of the HSDT model. The accuracy and reliability of the proposed method is verified by comparing its numerical predictions with those of other available numerical approaches. [less ▲]Detailed reference viewed: 202 (11 UL) Isogeometric analysis of functionally graded plates using a refined plate theoryNguyen-Xuan, H.; Tran, L. V.; Thai, C. H. et alin Composites : Part B, Engineering (2014), 64We present in this paper a simple and effective approach that incorporates isogeometric finite element analysis (IGA) with a refined plate theory (RPT) for static, free vibration and buckling analysis of ... [more ▼]We present in this paper a simple and effective approach that incorporates isogeometric finite element analysis (IGA) with a refined plate theory (RPT) for static, free vibration and buckling analysis of functionally graded material (FGM) plates. A new inverse tangent distributed function through the plate thickness is proposed. The RPT enables us to describe the non-linear distribution of shear stresses through the plate thickness without any requirement of shear correction factors (SCF). IGA utilizes basis functions namely B-splines or non-uniform rational B-splines (NURBS) which reach easily the smoothness of any arbitrary order. It hence satisfies the C1 requirement of the RPT model. The present method approximates the displacement field with four degrees of freedom per each control point allowing an efficient solution process. [less ▲]Detailed reference viewed: 75 (3 UL) Isogeometric Analysis of Laminated Composite Plates Using the Higher-Order Shear Deformation TheoryThai, Chien H.; Nguyen-Xuan, H.; Bordas, Stéphane et alin Mechanics of Advanced Materials and Structures (2015), 22(6), 451-469Isogeometric analysis (IGA) aims at simplifying the computer aided design (CAD) and computer aided engineering (CAE) pipeline by using the same functions to describe the geometry (CAD) and the unknown ... [more ▼]Isogeometric analysis (IGA) aims at simplifying the computer aided design (CAD) and computer aided engineering (CAE) pipeline by using the same functions to describe the geometry (CAD) and the unknown fields (Analysis). IGA can be based on a variety of CAD descriptions, the most widely used today being non-uniform rational B-splines (NURBS). In this article, the suitability of NURBS-based isogeometric analysis within a third-order shear deformation theory for the simulation of the static, dynamic, and buckling response of laminated composite plates is investigated. The method employs NURBS basis functions to both represent the geometry (exactly) and the unknown field variables. One of the main advantages of the present method is directly inherited from IGA, that is to easily increase the approximation order. To avoid using a shear correction factor, a third-order shear deformation theory (TSDT) is introduced. It requires C1-continuity of generalized displacements and the NURBS basis functions are well suited for this requirement. Several numerical examples are used to demonstrate the performance of the present method compared with other published ones. [less ▲]Detailed reference viewed: 78 (2 UL) Isogeometric analysis of thin Reissner-Mindlin plates and shells: Locking phenomena and generalized local B-bar methodHu, Qingyuan ; Xia, Yang; Natarajan, Sundararajan et alE-print/Working paper (2017)We propose a generalized local $\bar{B}$ framework, addressing locking in degenerated Reissner-Mindlin plate and shell formulations in the context of isogeometric analysis. Parasitic strain components are ... [more ▼]We propose a generalized local $\bar{B}$ framework, addressing locking in degenerated Reissner-Mindlin plate and shell formulations in the context of isogeometric analysis. Parasitic strain components are projected onto the physical space locally, i.e. at the element level, using a least-squares approach. The formulation is general and allows the flexible utilization of basis functions of different order as the projection bases. The present formulation is much cheaper computationally than the global $\bar{B}$ method. Through numerical examples, we show the consistency of the scheme, although the method is not Hu-Washizu variationally consistent. The numerical examples show that the proposed formulation alleviates locking and yields good accuracy for various thicknesses, even for slenderness ratios of $1 \times 10^5$, and has the ability to capture deformations of thin shells using relatively coarse meshes. From the detailed numerical study, it can be opined that the proposed method is less sensitive to locking and mesh distortion. [less ▲]Detailed reference viewed: 210 (15 UL) Isogeometric analysis using polynomial splines over hierarchical T-meshes for two-dimensional elastic solidsNguyen-Thanh, N.; Nguyen-Xuan, H.; Bordas, Stéphane et alin Computer Methods in Applied Mechanics & Engineering (2011), 200(21-22), 1892-1908Isogeometric analysis has become a powerful alternative to standard finite elements due to its flexibility in handling complex geometries. One of the major drawbacks of NURBS-based isogeometric finite ... [more ▼]Isogeometric analysis has become a powerful alternative to standard finite elements due to its flexibility in handling complex geometries. One of the major drawbacks of NURBS-based isogeometric finite elements is the inefficiency of local refinement. In this study, we present an alternative to NURBS-based isogeometric analysis that allows for local refinement. The idea is based on polynomial splines and exploits the flexibility of T-meshes for local refinement. The shape functions satisfy important properties such as non-negativity, local support and partition of unity. Several numerical examples are used to demonstrate the reliability of the present method. [less ▲]Detailed reference viewed: 68 (1 UL) Isogeometric analysis: an overview and computer implementation aspectsNguyen, Vinh-Phu; Anitescu, Cosmin; Bordas, Stéphane et alLearning material (2013)Isogeometric analysis (IGA) represents a recently developed technology in computational mechanics that offers the possibility of integrating methods for analysis and Computer Aided Design (CAD) into a ... [more ▼]Isogeometric analysis (IGA) represents a recently developed technology in computational mechanics that offers the possibility of integrating methods for analysis and Computer Aided Design (CAD) into a single, unified process. The implications to practical engineering design scenarios are profound, since the time taken from design to analysis is greatly reduced, leading to dramatic gains in efficiency. The tight coupling of CAD and analysis within IGA requires knowledge from both fields and it is one of the goals of the present paper to outline much of the commonly used notation. In this manuscript, through a clear and simple Matlab⃝R implementation, we present an introduction to IGA applied to the Finite Element (FE) method and related computer implementation aspects. Furthermore, implemen- tation of the extended IGA which incorporates enrichment functions through the partition of unity method (PUM) is also presented, where several examples for both two-dimensional and three-dimensional fracture are illustrated. The open source Matlab⃝R code which accompanies the present paper can be applied to one, two and three-dimensional problems for linear elasticity, linear elastic fracture mechanics, structural mechanics (beams/plates/shells including large displacements and rotations) and Poisson problems with or without enrichment. The B ́ezier extraction concept that allows FE analysis to be performed efficiently on T-spline geometries is also incorporated. The article includes a summary of recent trends and developments within the field of IGA. [less ▲]Detailed reference viewed: 905 (11 UL) Isogeometric and multi-scale fractureBordas, Stéphane Presentation (2015, July 31)Detailed reference viewed: 160 (10 UL) An isogeometric boundary element method for elastostatic analysis: 2D implementation aspectsSimpson, Robert; Bordas, Stéphane ; Lian, Haojie et alin Computers & Structures (2013), 118Detailed reference viewed: 523 (19 UL) An isogeometric boundary element method for elastostatic analysis: 2D implementation aspectsSimpson, R. N.; Bordas, Stéphane ; Lian, H. et alin Computers & Structures (2013), 118The concept of isogeometric analysis, whereby the parametric functions that are used to describe CAD geometry are also used to approximate the unknown fields in a numerical discretisation, has progressed ... [more ▼]The concept of isogeometric analysis, whereby the parametric functions that are used to describe CAD geometry are also used to approximate the unknown fields in a numerical discretisation, has progressed rapidly in recent years. This paper advances the field further by outlining an isogeometric boundary element Method (IGABEM) that only requires a representation of the geometry of the domain for analysis, fitting neatly with the boundary representation provided completely by CAD. The method circumvents the requirement to generate a boundary mesh representing a significant step in reducing the gap between engineering design and analysis. The current paper focuses on implementation details of 2D IGABEM for elastostatic analysis with particular attention paid towards the differences over conventional boundary element implementations. Examples of Matlab® code are given whenever possible to aid understanding of the techniques used. [less ▲]Detailed reference viewed: 301 (3 UL) Isogeometric finite element analysis using polynomial splines over hierarchical T-meshesNguyen-Thanh, Nhon; Nguyen-Xuan, Hung; Bordas, Stéphane et alin IOP Conference Series: Materials Science and Engineering (2014), 10(1), Isogeometric finite element analysis has become a powerful alternative to standard finite elements due to their flexibility in handling complex geometries. One major drawback of NURBS based isogeometric ... [more ▼]Isogeometric finite element analysis has become a powerful alternative to standard finite elements due to their flexibility in handling complex geometries. One major drawback of NURBS based isogeometric finite elements is their less effectiveness of local refinement. In this study, we present an alternative to NURBS based isogeometric finite elements that allow for local refinement. The idea is based on polynomial splines and exploits the flexibility of T-meshes for local refinement. The shape functions satisfy important properties such as non-negativity, local support and partition of unity. We will demonstrate the efficiency of the proposed method by two numerical examples. [less ▲]Detailed reference viewed: 65 (0 UL) Isogeometric locking-free plate element: a simple first order shear deformation theory for functionally graded platesShuohui, Yin; Hale, Jack ; Yu, Tiantang et alin Composite Structures (2014), 118An effective, simple, robust and locking-free plate formulation is proposed to analyze the static bending, buckling, and free vibration of homogeneous and functionally graded plates. The simple first ... [more ▼]An effective, simple, robust and locking-free plate formulation is proposed to analyze the static bending, buckling, and free vibration of homogeneous and functionally graded plates. The simple first-order shear deformation theory (S-FSDT), which was recently presented in Thai and Choi (2013) [11], is naturally free from shear-locking and captures the physics of the shear-deformation effect present in the original FSDT, whilst also being less computationally expensive due to having fewer unknowns. The S-FSDT requires C1-continuity that is simple to satisfy with the inherent high-order continuity of the non-uniform rational B-spline (NURBS) basis functions, which we use in the framework of isogeometric analysis (IGA). Numerical examples are solved and the results are compared with reference solutions to confirm the accuracy of the proposed method. Furthermore, the effects of boundary conditions, gradient index, and geometric shape on the mechanical response of functionally graded plates are investigated. [less ▲]Detailed reference viewed: 439 (27 UL) Isotropic–isotropic phase separation and spinodal decomposition in liquid crystal–solvent mixturesReyes, Catherine ; Baller, Jörg ; Araki, Takeaki et alin Soft Matter (2019), 15Phase separation in mixtures forming liquid crystal (LC) phases is an important yet under- appreciated phenomenon that can drastically influence the behaviour of a multi-component LC. Here we demonstrate ... [more ▼]Phase separation in mixtures forming liquid crystal (LC) phases is an important yet under- appreciated phenomenon that can drastically influence the behaviour of a multi-component LC. Here we demonstrate, using polarising microscopy with active cooling as well as differential scanning calorimetry, that the phase diagram for mixtures of the LC-forming compound 4’-n- pentylbiphenyl-4-carbonitrile (5CB) with ethanol is surprisingly complex. Binary mixtures reveal a broad miscibility gap that leads to phase separation between two distinct isotropic phases via spinodal decomposition or nucleation and growth. On further cooling the nematic phase enters on the 5CB-rich side, adding to the complexity. Significantly, water contamination dramatically raises the temperature range of the miscibility gap, bringing up the critical temperature for spinodal de- composition from ∼ 2◦C for the anhydrous case to > 50◦C if just 3 vol.% water is added to the ethanol. We support the experiments with a theoretical treatment that qualitatively reproduces the phase diagrams as well as the transition dynamics, with and without water. Our study highlights the impact of phase separation in LC-forming mixtures, spanning from equilibrium coexistence of multiple liquid phases to non-equilibrium effects due to persistent spatial concentration gradients. [less ▲]Detailed reference viewed: 71 (6 UL) An iterative learning approach for anticipatory traffic signal control on urban networksHuang, Wei; Viti, Francesco ; Tampere, Chrisin Transportmetrica B: Transport Dynamics (2017), 5(4), 407-430Detailed reference viewed: 74 (2 UL) An iterative learning approach for anticipatory traffic signal control on urban networksHuang, Wei; Viti, Francesco ; Tampere, Chrisin Transportmetrica B: Transport Dynamics (2016)Detailed reference viewed: 103 (6 UL) An Iterative Learning Approach for Signal Control in Urban Traffic NetworksHuang, Wei; Viti, Francesco ; Tampere, Chris M.J.in Proceedings of IEEE-ITS Conference (2013)Traffic signal control influences route choice in traffic networks, and may even determine whether a traffic system settles in equilibrium or destabilizes into oscillatory patterns. Ideally, a stable ... [more ▼]Traffic signal control influences route choice in traffic networks, and may even determine whether a traffic system settles in equilibrium or destabilizes into oscillatory patterns. Ideally, a stable equilibrium flow pattern should result from the interaction between control and route choice on a long-term horizon. This paper proposes an iterative learning approach for designing signal controls able to attract the system to equilibrium in an acceptable convergence speed. The traffic assignment model and combined traffic assignment and control problem are first introduced. An iterative learning control (ILC) based signal control is formulated and a basic model inversion method is analyzed. To deal with the nonlinearity of traffic system, a Newton based ILC algorithm is applied. Test in an example network verifies the effectiveness of the ILC method in achieving stable equilibrium in the traffic system. [less ▲]Detailed reference viewed: 104 (0 UL) An iterative Mixed Integer Linear Programming Approach to pursuit evasion problems in polygonal environmentsThunberg, Johan ; Ögren, P.in Proceedings of the 2010 IEEE International Conference on Robotics and Automation (ICRA) (2010)In this paper, we address the multi pursuer version of the pursuit evasion problem in polygonal environments. It is well known that this problem is NP-hard, and therefore we seek efficient, but not ... [more ▼]In this paper, we address the multi pursuer version of the pursuit evasion problem in polygonal environments. It is well known that this problem is NP-hard, and therefore we seek efficient, but not optimal, solutions by relaxing the problem and applying the tools of Mixed Integer Linear Programming (MILP) and Receding Horizon Control (RHC). Approaches using MILP and RHC are known to produce efficient algorithms in other path planning domains, such as obstacle avoidance. Here we show how the MILP formalism can be used in a pursuit evasion setting to capture the motion of the pursuers as well as the partitioning of the pursuit search region into a cleared and a contaminated part. RHC is furthermore a well known way of balancing performance and computation requirements by iteratively solving path planning problems over a receding planning horizon, and adapt the length of that horizon to the computational resources available. The proposed approach is implemented in Matlab/Cplex and illustrated by a number of solved examples. [less ▲]Detailed reference viewed: 85 (0 UL) Iterative optimization for adaptive anticipatory control in urban traffic networksHuang, Wei; Viti, Francesco ; Tampere, Chris M.J.Scientific Conference (2015, July)Detailed reference viewed: 55 (1 UL)