Technical Sessions A1 - D1

SESSION A1: Graph Theory and Applications

[181] Formulations for the Balanced Vertex k-Separator Problem
Denis Cornaz, Fabio Furini, Mathieu Lacroix, Enrico Malaguti, A. Ridha Mahjoub and Sébastien Martin

Given an indirected graph G=(V,E), a Vertex k-Separator is a subset of the vertex set V such that, when the separator is removed from the graph, the remaining vertices can be partitioned into k subsets that are pairwise edge-disconnected. In this paper we focus on the Balanced Vertex k-Separator Problem, i.e., the problem of finding a minimum cardinality separator such that the sizes of the resulting disconnected subsets are balanced. We present a compact Integer Linear Programming formulation for the problem, and present a polyhedral study of the associated polytope. We also present an Exponential-Size formulation, for which we derive a column generation and a branching scheme. Preliminary computational results are reported comparing the performance of the two formulations on a set of benchmark instances.

[108] Weighted Dominating Sets and Induced Matchings in Orthogonal Ray Graphs
Asahi Takaoka, Satoshi Tayu and Shuichi Ueno

An orthogonal ray graph is a graph such that for each vertex, there exists an axis-parallel rays (closed half-lines) in the plane, and two vertices are adjacent if and only if the corresponding rays intersect. A 2-directional orthogonal ray graph is an orthogonal ray graph such that the corresponding ray of each vertex is a rightward ray or a downward ray. We recently showed in [12] that the weighted dominating set problem can be solved in O(n4 log n) time for vertex-weighted 2-directional orthogonal ray graphs by using a new parameter, boolean-width of graphs, where n is the number of vertices in a graph. We improve the result by showing an O(n3)-time algorithm to solve the problem, based on a direct dynamic programming approach. We also show that the weighted induced matching problem can be solved in O(m6) time for edge-weighted orthogonal ray graphs, where m is the number of edges in a graph, closing the gap posed in [12].

[243] Two bounds of chromatic number in graphs coloring problem
Assia Gueham, Anass Nagih and Hacene Ait Haddadene

In this paper, we essentially focus on the coloration approach and estimation of chromatic number. We propose a first upper bound of a chromatic number based on the orientation algorithm. This upper bound is improved by developing a novel coloration algorithm. Finally, we make a theoretical and empirical comparison of our bounds with Brooks’s bound and Reed’s conjecture for class of triangle-free graphs.

SESSION B1: Robotics and Control

[151] Control Strategy for Continuous Lactic Acid Production from Wheat Flour
Karen Gonzalez, Sihem Tebbani, Filipa Lopes, Didier Dumur, Dominique Pareau, Sébastien Givry and Françoise Entzmann

The application of white biotechnology to produce biopolymers has increased recently. In this study, a control strategy for lactic acid production process from wheat flour is proposed. First, the process model to be used in the control strategy is chosen after performing an observability analysis of the system. Then, the optimal setpoint that maximizes the lactic acid productivity is determined based on this simplified model. Finally, the regulation of lactic acid concentration to its optimal value is considered. The designed control law uses a state-feedback linearizing controller in an inner loop together with a proportional integral (PI) regulator in an outer loop. An anti-windup mechanism is added in order to improve the control law performances. The efficiency of the proposed control strategy is illustrated and assessed by means of simulation results.

[171] Intelligent Robotics in 3D Simulation - An eRobotics Approach
Eric Guiffo Kaigom and Jürgen Rossmann

Robot manipulators are increasingly employed in various applications prone to uncertainties. Therefore, intermittent weak and strong physical interactions with the surrounding operational environment can occur. Managing the complexity related to this trend requires simulation capabilities going far beyond traditional off-line motion planning of robots in freespace. This paper presents a novel dynamic simulation approach that addresses these issues. The approach conveys insight into the accommodation of external forces during physical interaction, since the simulated robots are endowed with force-sensitive and compliance control capabilities. Going many steps further, the symbiotic simulation of compliance control enables physical interaction between a human operator and a real position-controlled robot. Our approach builds upon a comprehensive, holistic and versatile coupling of modeling paradigms. It leverages the significance of simulation outcomes by enriching the simulator with advanced and realistic robot control techniques. It deepens the understanding of ongoing processes by allowing an overall and customizable view on the robot down to actuators. The results highlight the effectiveness of the eRobotics methodology, which represents the foundation this work is built upon.

[12] A Simple Application of GPI Observers to the Force Control of Robots
Marco Antonio Arteaga Perez and Alejandro Gutierrez Giles

In this work the design of a linear observer--linear controller robust output feedback scheme is introduced for simultaneous trajectory tracking of position and force in fully actuated robot manipulators. The unknown state--dependent additive nonlinearity influencing the input--output description is modeled as an absolutely bounded "time-varying perturbation". Generalized Proportional Integral (GPI) observers are shown to naturally estimate the unknown perturbation and a certain number of its time derivatives in an arbitrarily close manner. This information is used to advantage on the linear feedback controller design via a simple cancelation effort. To the best of the authors' knowledge GPI observers have not been used before for robot force control. A experimental analysis/comparison is presented to show the good performance of the proposed approach.

SESSION C1: Adaptive E-learning systems with social interactions

[43] Social interaction inside the cMOOC #ExIF13 Adaptive e-learning in distance education on a new track!?
Sebastian Vogt and Markus Deimann

This paper for the CODIT2014 Special Session on “Adaptive E-learning systems with social interaction” revolves around the question of what potentials a cMOOC as adaptive e-learning system with social interaction offers for distance studies. Answers are suggested by looking at the cMOOC “Discover the Island of Research” (#ExIF13) presented by FernUniversität in Hagen in the summer semester 2013. The seven-week, video-based, German-language expedition trip followed the concept of “Educational TV reloaded” [19]. The idea comprises the use of social media in order to complement the proven formats of (internet-based) educational television with live feedback and networking opportunities in the sense of self-controlled connectivist learning.

[52] Modelling emotions in an on-line educational game
Peter Robinson

Emotional expression and recognition are important in social interactions between people. This is particularly evident in communications between a teacher and a pupil when facial expressions signal levels of understanding and enjoyment will change the teacher's explanation to a pupil, and effective e-learning systems must adapt in the same way if they are provide the social interactions that are necessary for effective pedagogy. Affective computing can equip computer systems with the ability to process social signals and respond accordingly. However, social signals are inherently ambiguous and confusion will result if the approach to processing them is too mechanistic. This paper presents and analyses empirical evidence for this ambiguity, and proposes a possible solution.

[68] Pattern Discovery in E-learning Courses: a Time-based Approach
Guillaume Blot, Francis Rousseaux and Pierre Saurel

This work relies on connectivism and focuses on the interactions between learners and resources of e-learning materials aiming to discover patterns [13]. The theory of connectivism mainly tells, that knowledge is available through a network of connections. Based on Social Network Analysis, our Time-graph representation uses temporal metrics [12]. Even though longitudinal networks are the most widely used representations of temporal factors, here we considerer time-distribution criterion within a single graph. Path following techniques are not new, but the Time-graph configuration makes it in a specific fashion, that orders resources over a timeline. A resource has not the same impact at the start or at the end of a course. Hence given a specific instant, the Time-graph can inform learners, about important resources.

[89] Adaptive Digital Resource Modelling for Interactive System
Sawadogo Daouda, Ronan Champagnat and Pascal Estraillier

The designing of the digital resources is an expensive process that consumming time and money. So to optimize the use in an adaptive process would reduce time for the designers and users. The increase in the production of digital data in these last few years, has raised several issues regarding the management of heterogeneous and multiple source data in the user’s environment. In this paper, we focus on adaptive digital resource modelling to assist users in the consolidated management of digital resources in an interactive and adaptive system. In this paper we propose an approach of digital resources modelling which will make the use of digital resources more adaptive. We introduce an adaptive resource model which includes LOM (Learning Object Metadata) metadata, manipulation rules and operators. This model allows an automatic adaptation to user’s profiles and user’s contexts. An experimental implementation called PRISE (Personal Interactive research Smart Environment) is carried out in our laboratory. PRISE is an interactive and adaptive system to assist researchers in using and managing their digital resources efficiently. PRISE architecture is based on three essential parts of the system : the user model, the process model and the resource model. Our aim is to maintain a consistency in terms of interaction between the users and the digital resources.

SESSION D1: Control and supervision of manufacturing systems

[189] Predictive Simulation Based Decision Support System for Resource Failure Management in Multi-Site Production Environments
Matthias Becker, Helena Szczerbicka and Sinan Balci

Planning in a multi-site, non-mass production environment is a special challenge because of several sources of uncertainty. Unlike in mass production facilities, in our setting the current state at all sites cannot be determined easily and exactly due to the spatial distribution of sites and the low degree of automation. For re-planning in case of failures, the possible alternative actions have to be formalized on the decision making facility, where the possible alternatives will then be determined and evaluated. In this work, we will present the necessary components for an automated evaluation of alternatives and decision support procedure. The main challenges are the formalization of product plans including alternative steps and the non-automated collection or assessment of the distributed system state of all sites.

[204] Artificial Intelligence for Help in Decision Making During Non Destructive Testing of Materials
Thouraya Merazi Meksen, Malika Boudraa and Bachir Boudraa

In non Destructive Testing of Materials, diffracted ultrasonic waves are used in semi automated techniques for crack detection. Signals are displayed as images and artificial intelligence may allow automated interpretation in order to give a help in the decision making, especially when large structures are inspected (pipelines, reactor vessels…).This paper describes a new approach for data storage, namely sparse matrix structure that avoids image formation. Only the coordinates of pertinent samples regarding a detected defect are stored in a 2D array. In addition to reducing significantly the amount of data to store and to process, sparse representation make possible the exploitation of pattern recognition methods such as Least Mean Square (LMS) algorithm to automatic interpretation. Indeed, when a crack is presented in a controlled structure, the graph formed by the sparse matrix elements have a parabolic form and its summit location deals with the crack summit position.

[91] Monitoring Simple Linear Profiles in the Presence of GARCH and non-Normality Effects
Paria Soleimani and Reza Hadizadeh

In some applications of statistical quality control, process quality is described by the relationship between a response variable and one or more explanatory variables that is called profile. Profile monitoring procedures assumes that error terms, ie , are uncorrelated random normal variables with zero mean and constant variance (homosedasticity). However in some applications, these assumptions can be violated and lead to fault interpretations. In this paper, generalized autoregressive conditional heteroscedasticity effect, namely, GARCH and non-normality distribution effect on the monitoring of simple linear profiles are studied. We show these effects on ARL (Average Run Length) criteria with simulation studies.

[71] Compensatory Neuro-fuzzy Control of Bilateral Teleoperation System
Rabah Mellah, Redouane Toumi, Laurent Catoire and Michel Kinnaert

In this paper a new adaptive controller using compensatory neurofuzzy is presented to guarantee the position and force tracking performance between the master and the slave manipulators. The controller proposed, combines in which one neural networks (NNs) with fuzzy logic for dynamical compensation of both structured and unstructured uncertainties, and in the other hand optimizes dynamically the adaptive fuzzy reasoning for acceleration the asymptotically convergence to zero the trajectory tracking error between the master and the slave robots. An analysis of stability and transparency based on a passivity framework is carried out. The validity of the proposed control scheme is demonstrated with a 1-DOF master/slave system. Finally the experimental results are performed to show that the proposed control method works well with robustness, so that confirm the effectiveness of the proposed controllers.