Hannes Wettig, Petri Kontkanen, Petri Myllymäki Complex Systems Computation

When learning Bayesian network structures from sample data, an important issue is how to evaluate the goodness of alternative network structures. Perhaps the most commonly used model (class) selection criterion is the marginal likelihood, which is obtai ned by integrating over a prior distribution for the model parameters. However, the problem of determining a reasonable prior for the parameters is a highly controversial issue, and no comple tely satisfying Bayesian solution has yet been presented in the non- informative setting. The normalized maximum lik elihood (NML), based on Rissanen's information- theoretic MDL methodology, offers an alternative, th eoretically solid criterion that is objective and non- informative, while no parameter prior is required. It has been previously shown that for discrete data, this criterion can be computed in linear time for Bayesian networks with no arcs, and in quadratic time for the so called Naive Bayes network structure. Here we extend the previous results by showing how to compute the NML criterion in polynomial time for tree- structured Bayesian networks. The order of the polynomial depends on the number of values of the variables, but neither on the number of variables itself, nor on the sample size1.

Barnabás Takács, PhD., 3 Head of Department

This paper describes a mobile Ambi ent Assisted Living (AAL) solution designed to meet the require- ments of modern health services in caring for, m onitoring and motivating the elderly in their own envi- ronment. Our solution goes beyond the function of cl assical telemonitoring by delivering integrated functionality that includes health management, mental monitoring, m ood assessment as well as physical and relaxation exercises. In addition, we provide co mmunication and delivery services in location-based manner using built in GPS, WiFi and 3G mobile c onnectivity (MediCAST). Bluetooth compatible blood pressure and body weight measurement devices are complemented with a body-mounted wireless physiological sensor to monitor activity, body temper ature and stress. Telemetric data is continuously recorded on a local host computer while simultaneously being also sent to a central database, where a rule-based system or monitoring health personnel ma y make emergency assessment. To further help the elderly, to monitor their own drug intake or diet ary goals we introduce a novel feedback and display methodology, called Ambient Facial Interfaces (AFI) that employ animated photo-realistic faces to show them in an easy-to-understand form their compliance levels. Finally, we describe a prototype of our fu- turistic AAL platform using home robots to help people with daily activities.

Mohammad M. R. Chowdhury UniK – University Graduate Center, P.O. Box, N- Kjeller, Norway. Researcher

Ubiquitous access and pervasive computing enable i nnovative services and provide the service access in every situation. People currently rely on numerous fo rms of identities to access remote or proximity services. The inconvenience of possessing and using these identitie s creates significant security vulnerability. This paper proposes an architecture that integrates the identities required to access various remote and proximity services. In the mechanism, identities are distributed into the user’s personal device and a secure network space. Third party identity providers along with the mobile network provide the underlying secure infrastructure for identity info rmation exchange. In this regard, the use of multi- factor authentication contexts meets different levels of service access security requirements. At the end, a prototypical implementation demonstrates a service access scenario based on the proposed mechanism.

Addisalem Negash, Vasile-Marian Scuturici, Lionel Brunie Laboratoire

: This paper presents SAMi, a context aware Information sharing Middleware, for a dynamic pervasive computing environment such as a Mobile Ad-hoc NETworks (MANET). SAMi can be used by co- located devices to share information according to the context of users and their environment. It applies latent semantic m odeling techniques and adopts techniques from service discovery to search files efficiently. A preliminary prototype has been deve loped to simulate MANETs and to implement the middleware. A number of experiment s have been performed to evaluate major features of SAMi. Based on these experiments, we found SAMi a promising middleware to facilitate information exchange among co-located devices.

D-r Vladimir Trajkovik, Slagana Gligorovska, D-r Danco Davcev

Distance Education System (DES) is commonly used to increase effectiveness of educational process. Mobile devices imply additional changes in the way students interact as a society. Mobile learning (m- Learning) offers solutions that address the shortcomings of the traditional classroom. The mobile virtual blackboard is elaborated in this paper. It is a mobile communication service integrated within our existing DES. It serves for consultations purposes and it is especially suitable for acquiring small and exact pieces of knowledge that can be immediately used. In that way, it creates an ideal environment for collaborative learning. The feasibility of using mobile virtual blackboard within educational process was performed with the survey done with the students at the last year of undergraduate studies. We found that functions of the mobile virtual blackboard were effective in cooperative learning. The feedback from the students proved that the virtual blackboard system was viable for use within any project based curriculum.

Lorraine Fisher UCD School of Business, Belfield Researcher, Dublin, Ireland Researcher

Increasing numbers of studies are starting to evaluate the usefulness of Tablet Personal Computer (PC) devices in teaching and instruction (Weitz et al., 2006, Hulls, 2005, Mock, 2004, Theys et al., 2005). In some instances Tablet PC use is combined with ot her mobile technologies (suc h as laptops ) to support classroom interactivity in computer science course s (Berque and Thede, 2006). This paper presents the results of one year of data collection and analysis undertaken by the School of Computing and Intelligent Systems, Faculty of Computing and Engineering, Magee Campus of the University of Ulster, Northern Ireland. This study investigated student and staff perc eptions of a Tablet PC initiative. The theoretical lens of situated learning theory (Lave and Wenger, 1991) is used to interpret these findings, which indicate that staff and student e ngagement in the School’s Tablet PC initiative has been generally positive, and enhanced teaching and learning both inside and outside of the classroom.

Maria José Marcelino Universidade de Coimbra, Dep. Eng. Informática – Polo II – Coimbra

Recently we have been assisting to an increase in the use of handheld software in education. Yet, in what concerns modeling and simulation, what we find most are closed packages, representing a specific situation, that once used become exhausted. We need tools that allow representing more situations easily and quickly. This motivated the development of Sim- H, an authoring system for handheld modeling and simulation that uses essentially di rect manipulation techni ques, various representation and interaction forms to create and test models and simulations. At the moment it is made by three editors, one for model building, or a modeling tool, a nother to create scenarios for models that are easier to interact with than the models themselv es, and a third one to include support to learning in a model or a scenario, namely extra information and guidance, that is to build simulations. Due to Sim-H architecture it is very easy to aggregate to a single model several scenarios or learning layers. In the scope of this paper we will focus mainly on the scenario editor, its characteristics and the kind of products it allows to build.

Thomas Hübner, Yanci Zhang, Renato Pajarola Visualization, Multimedia Lab

The fundamental drawback of current stereo and multi-view display techniques is the necessity to perform multi-pass rendering (one pa ss for each separate view) and subsequent image composition-and- masking for generating multi-stereo views. Thus the re ndering time increases in general linearly with the number of rendered views. An incr ease in frame-rate can be achieve d by sub-resolution rendering and extrapolation before display, at the expense of degraded image quality. To overcome these disadvantages, we introduce a new method for renderi ng volumes, points and triangles meshes on multi-view auto-stereoscopic disp lays. Our method exploits the programmability of modern graphic processing units (GPUs) for rendering multi-stereo views in a single rendering pass. The views are calculated directly on the GPU including s ub-pixel wavelength select ive views. We describe our algorithm precisely and provide details about its implem entation. Experimental results demonstrate the performance advantages of our single-pass multi-view rendering algorithms compared to the standard multi-pass rendering approaches.

Sergi Grau, Dani Tost Divisió Inormàtica Gràfica, Centre de Recerca de Enginyeria

Image-Space Sheet-Buffered Splatting is a popular hi gh quality volume-rendering technique specially suitable for zoomed views of the data and point-based surface models, that projects the voxels in slabs perpendicular to the viewing direction. Recently, a GPU design of this method has been proposed that considerably accelerates the render ing stage. However, the bottleneck of the method is the computation of the buckets, i.e the structure handling the voxels to be rendered in each slab. This stage of the method is done on the CPU. In this paper, we propose a ne w design of the method that creates and manages the buckets on the GPU. The proposed method is more than three times faster than the previous ones.

Nicoletta Adamo-Villani, David Jones Purdue University, Department of Computer

This paper describes the developmen t and evaluation of three (3) firs t-person travel interfaces for immersive environments. The three interfaces presen ted in the paper have been developed for the SMILE™ project ( Science and Math in an Immersive Learning Environment), an immersive learning game that employs a fantasy 3D virtual world to e ngage deaf and hearing children in math and science- based educational tasks. Two interfaces are hand-based, while the third one allows for hands-free motion control. The evaluation aims to: (1) determine which interface is the most effective for the hearing users of SMILE™ in terms of accuracy, speed, appeal, and ease of learning, and (2) identify any gender differences in using the three travel methods. To accomplish this objective we have designed an experiment which compares the three techniques for moving directly to a target object; we varied the distance of the object from the user’s starting positi on and the complexity of the path (number of turns) to reach the destination. Ten (10) hearing children ages 6–11 participated in the study; results show that although all travel techniques are easy to comprehend a nd use, the wand is the most effective interface. To our knowledge, this is the first paper that reports a study of i mmersive travel techniques with children. In a future publication we will report th e results of the same e xperiment with non-hearing children.

Joachim Georgii, Jens Krüger, Rüdiger Westermann Computer Graphics

If two closed polygonal objects with outfacing normals intersect each other there exist one or more lines that intersect these objects at at l east two consecutive front or back fa cing object points. In this work we present a method to efficiently detect these lines us ing depth-peeling and simple fragment operations. Of all polygons only those having an inte rsection with any of these lines ar e potentially colliding. Polygons not intersected by the same line do not intersect each other. We describe ho w to find all potentially colliding polygons and the potentially colliding pairs using a mipmap hierarchy that represents line bundles at ever increasing width. To download onl y potentially colliding polygons to the CPU for polygon-polygon intersection testing, we have developed a general me thod to convert a sparse texture into a packed texture of reduced size. Our method expl oits the intrinsic strength of GPUs to scan convert large sets of polygons and to shade billions of fragm ents at interactive rates. It neither requires a bounding volume hierarchy nor a pre-processing stage, so it can efficiently deal with very large and deforming polygonal models. The particular design makes the method suitable for applications where geometry is modified or even created on the GPU.

Zuzana K ´ukelov´a∗

In this work we focus on function representation suitable for creating 3D freeform shapes with sketched silhouette curves. We aim at comparison of two approaches for sketch-based modeling, namely the skeleton-based convolu- tion surfaces and variational implicit surfaces. Both methods are extended to handle smooth set theoretic operations between components defined by sketching silhouette curves on different projection planes. Our approach includes additional extensions to sketch-based systems like automatic skeleton generation that can be directly used for object animation, carving operation, creating surfaces with handles and surface texturing. 1

Keren Kapach, Yael Edan Department of Industrial Engineering, Management Researcher

This paper presents a thorough evaluation of grid map based sensor fusion algorithms for mapping the environment of a mobile robot. Three physical sensors were used for creating the grid maps: a CCD camera, a set of ultrasonic sensors and a laser rangefinder. An adaptive fuzzy logic algorithm was compared to three logical sensor fusion algorithms. Results indicate the superiority of the adaptive fuzzy logic algorithm with a 0.075 confidence level.

Pedro Isaías

Editorial preface for Volume 2, Issue 2 of the IADIS International Journal on Computer Science and Information Systems (IJCSIS). This issue brings together peer-reviewed original research contributions covering the wide spectrum of Information Systems, Artificial Intelligence, Software Engineering, and Digital Transformation.