Classification of noisy signals using fuzzy ARTMAP neural networks

This paper describes an approach to classification of noisy signals using a technique based on the fuzzy ARTMAP neural network (FAMNN). The proposed method is a modification of the testing phase of the fuzzy ARTMAP that exhibits superior generalization performance compared to the generalization performance of the standard fuzzy ARTMAP in the presence of noise. An application to textured gray-scale image segmentation is presented. The superiority of the proposed modification over the standard fuzzy ARTMAP is established by a number of experiments using various texture sets, feature vectors and noise types. The texture sets include various aerial photos and also samples obtained from the Brodatz album. Furthermore, the classification performance of the standard and the modified fuzzy ARTMAP is compared for different network sizes. Classification results that illustrate the performance of the modified algorithm and the FAMNN are presented.     

A Data‐Driven Framework for Visual Crowd Analysis

We present a novel approach for analyzing the quality of multi‐agent crowd simulation algorithms. Our approach is data‐driven, taking as input a set of user‐defined metrics and reference training data, either synthetic or from video footage of real crowds. Given a simulation, we formulate the crowd analysis problem as an anomaly detection problem and exploit state‐of‐the‐art outlier detection algorithms to address it. To that end, we introduce a new framework for the visual analysis of crowd simulations. Our framework allows us to capture potentially erroneous behaviors on a per‐agent basis either by automatically detecting outliers based on individual evaluation metrics or by accounting for multiple evaluation criteria in a principled fashion using Principle Component Analysis and the notion of Pareto Optimality. We discuss optimizations necessary to allow real‐time performance on large datasets and demonstrate the applicability of our framework through the analysis of simulations created by several widely‐used methods, including a simulation from a commercial game.     

Estimation of the value of life saving under uncertainty emanating from transport infrastructure investment A theoretical exposition with an application to the Rion-Antirion suspension bridge in Greece

In this paper a model for estimating the reduction of the probability of premature death emanating from a transport infrastructure investment is developed. As a starting point a reference probability of premature death is arbitrarily chosen and two measures of estimating the value of life saving are constructed based on the willingness to pay for the reduction in the casualty rate. These two measures are derived from the comparison of the probabilities of premature death before and after the reduction in the casualty rate to the corresponding reference probability. It is then shown that the relationship between the first measure and the reference probability premature death is upward sloping and concave and the relationship between the second measure and the reference probability of premature death is upward sloping and convex. Finally, we empirically tested both measures in the case of the Rion-Antirion suspension bridge which will connect the Western part of Greece through the Rion-Antirion sea strait with the region of Patras and consequently with Athens, providing a faster and more efficient service for the passage of the sea strait than the existing obsolete ferry system. The empirical results show that the theoretical propositions with respect to the concavity and convexity of the functions of each measure with the reference probability are verified. Received July 1997/ Accepted February 1998     

Thermomechanical properties and rheological behavior of biodegradable composites

The effect of type and content of fillers on the thermal, mechanical, and rheological behavior of the commercial biodegradable polyester product, Ecovio® (BASF) is analytically studied. Ecovio® is basically a blend of poly(butylene adipate‐terephthalate) (PBAT) copolyester (Ecoflex®, BASF) and polylactide (PLA). Two different types of fillers (nanosilica particles and micro‐sized wood‐flour), at various weight fractions were used for this purpose. The role of these fillers on the thermomechanical performance of Ecovio® was investigated in terms of several experimental techniques including scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), creep, tensile testing, and single cantilever bending. The rheological behavior has been systematically analyzed, providing additional evidence about the dispersion quality and the interfacial effects between nanofillers and matrix. One of the findings of this work is that the presence of PBAT in the blend (PLA/PBAT) enhances the compatibility of the polymer matrix with both fillers and their dispersion quality. POLYM. COMPOS., 35:1140–1149, 2014. © 2013 Society of Plastics Engineers     

On surface growth of actin networks

A continuum theory of surface growth is applied to the mechanical modeling of cell motility. The theory relies on a decomposition of the motion into deformation- and growth-inducing parts. A non-dissipative constitutive relation is adopted and expressed exclusively in terms of the current configuration. The resulting model is used in the simulation of a network of actin filaments, and a simple one-dimensional example is included to showcase its predictive capacity.     

A fast outlier detection strategy for distributed high-dimensional data sets with mixed attributes

Outlier detection has attracted substantial attention in many applications and research areas; some of the most prominent applications are network intrusion detection or credit card fraud detection. Many of the existing approaches are based on calculating distances among the points in the dataset. These approaches cannot easily adapt to current datasets that usually contain a mix of categorical and continuous attributes, and may be distributed among different geographical locations. In addition, current datasets usually have a large number of dimensions. These datasets tend to be sparse, and traditional concepts such as Euclidean distance or nearest neighbor become unsuitable. We propose a fast distributed outlier detection strategy intended for datasets containing mixed attributes. The proposed method takes into consideration the sparseness of the dataset, and is experimentally shown to be highly scalable with the number of points and the number of attributes in the dataset. Experimental results show that the proposed outlier detection method compares very favorably with other state-of-the art outlier detection strategies proposed in the literature and that the speedup achieved by its distributed version is very close to linear.     

Specifying the dynamics of social technologies as social microworlds

This paper explores the affordances of social technologies for supporting the construction of a shareable artefact by a group of learners. A qualitative study that captures the use of five different types of social technologies (Facebook, blogs, wikis, Google Documents and Dropbox) in three different classroom settings sheds light on the potentials and challenges of these tools for supporting material exploration, artefact construction and evaluation. Qualitative content analysis of instructors’ field notes, students’ and instructors’ reflections, interviews and focus groups sheds light on the potential of social technologies to transform the activity of learning across a new culture of computational tools. The affordances of social technologies are discussed as well as design principles that need to be followed in these new arenas.     

Interaction design studio learning in virtual worlds

The paper suggests that virtual worlds (VWs) have many unique advantages for supporting interaction design studio activities, provided that they are designed to include appropriate workplaces and interactive tools to foster collaboration and creativity. We present an approach for employing VWs that proposes the use of prospective tools and workplaces throughout the following key activities of interaction design studio courses: design brief, design thinking, design practice (conceptual and detailed), the desk crit, design review and user evaluation. Then, we describe a blended interaction design studio course on the basis of this approach, which ran through a whole semester. We found that the VW design studio is an engaging and constructive experience for students: In the VW environment, students and tutors held many online meetings, and students constructed several models about their design project, developed a digital prototype and conducted a remote usability evaluation. In addition, the persistence of the environment and the developed VW tools helped students and tutors to achieve careful feedback and reflection during the design project lifetime. Nevertheless, a number of challenges remain for wider implementation: the refinement of the instructional design approach, the usability of VW tools, further integration of VWs to professional design tools and the conduction of other full-scale VW design studio courses.     

Kinesthetic interactions in museums: conveying cultural heritage by making use of ancient tools and (re-) constructing artworks

Kinesthetic interactions allow users to interact with 3D applications through their body movements and hand gestures. When kinesthetic applications are introduced in museums and heritage institutions, they add embodiment to visitor experience. An appropriate fit for kinesthetic technology in museums rests on visitors engaging in purposeful body movements and hand gestures that convey meanings about both intangible and tangible heritage. This paper presents the design, development and evaluation of a kinesthetic application of sculpturing Cycladic figurines, which places the user at the role of an ancient craftsman who creates a figurine with bare-hand movements (translated by Leap Motion to respective sculpting actions) in a simplified virtual environment. The Cycladic sculpture application has been evaluated in laboratory and field testing (as part of a wider educational activity in the museum) with positive results on usability, fun and learning. We identify several benefits as well as challenges of designing kinesthetic interactions in museums and we report on design issues that need to be taken into account in similar applications.