Abstract. A polytope is inscribable if there is a realization where all vertices lie on the sphere. In this paper, we provide a necessary and sufficient condition for a polytope to be inscribable. Based on this condition, we characterize the problem of determining inscribability as a minimum rank optimization problem using slack matrices. We propose a semidefinite programming (SDP) approximation for the minimum rank optimization problem and prove that it is tight for certain classes of polytopes. Given a polytope, we provide three algorithms to determine its inscribability. All the optimization problems and algorithms we propose in this paper depend on the number of vertices and facets but are independent of the dimension of the polytope. Numerical results demonstrate our SDP approximation’s efficiency, accuracy, and robustness for determining inscribability of simplicial polytopes of dimensions [Formula: see text] with vertices [Formula: see text], revealing its potential in high dimensions.

We propose a novel online real-time gait terrain detection algorithm from the measurements of a foot-mounted Inertial Measurement Unit (IMU), using a shallow cascaded Convolutional and Long Short-Term Memory neural network (CNN-LSTM). Gait data is acquired from healthy subjects walking in an unstructured environment that includes level ground, stair ascent and stair descent. The CNN-LSTM subject-independent classifier is trained to continuously detect the terrain from the time series data, invariant to IMU initial pose. Our results show that the classifier is able to correctly detect the terrain on data from unseen subjects, in less than 90ms from toe-off (f1-score >0.89), improving further its classification performance in less than 135ms from toe-off (f1-score >0.98). Furthermore, we present a novel capability with this classifier to timely detect terrain transitions, switching from the starting to the final terrain during midswing. The CNN-LSTM classifier is therefore suitable to be used in assistive devices, timely adjusting to the different gait kinematics, using a single foot-mounted IMU.

While HCI remains vastly abundant in human- and land- centric applications, in this work we focus on exploring further the Human Computer Biosphere Interaction (HCBI) concept in aquatic settings. Based on the existing techniques for prototyping the geodesic domes, we design them as five marine megafauna species, for the on- and off- shore locations. We describe novel interaction concepts with and within such structures: (i) Turtle AR nesting, (ii) Bird XR watching, (iii) Dolphin acoustic swimming, (iv) Seal night scuba-diving, and (v) Whale projection mapping. We report the design of such interaquatic environments, focused at depicting the ongoing concerns with such marina megafauna species, discussing their feasibility, suggesting research, implementation and validation for all interaquatic domes, planned in our future work.

In this paper we introduce a natural model for the realization space of a polytope up to projective equivalence which we call the slack realization space of the polytope. The model arises from the positive part of an algebraic variety determined by the slack ideal of the polytope. This is a saturated determinantal ideal that encodes the combinatorics of the polytope. We also derive a new model of the realization space of a polytope from the positive part of the variety of a related ideal. The slack ideal offers an effective computational framework for several classical questions about polytopes such as rational realizability, nonprescribability of faces, and realizability of combinatorial polytopes.

In this paper we study various versions of extension complexity for polygons through the study of factorization ranks of their slack matrices. In particular, we develop a new asymptotic lower bound for their nonnegative rank, decreasing the gap between the current bounds, we introduce a new upper bound for their boolean rank, deriving some numerical evidence for the asymptotic equivalence of the boolean rank of $n$-gons and $\log_2(n)$, and we show the nonmonotonicity of the complex positive semidefinite rank of $n$-gons.

Image matching algorithms are used in image search, classification and retrieval but are also useful to show how urban structures evolve over time. Images have the power to illustrate and evoke past events and can be used to show the evolution of structures such as buildings and other elements present in the urban landscape. The paper describes a process and a tool to provide a chronological journey through time, given a set of photographs from different time periods. The developed tool provides the ability to generate visualizations of a geographic location, given a set of related images, taken at different periods in time. It automatically processes comparisons of images and establishes relationships between them. It also offers a semi-automated method to define relationships between parts of images.

This article describes an architecture for authentication and uniform access to protected data stored on popular Cloud Storage Service Providers. This architecture takes advantage of the OAuth authentication mechanism and the strong authentication mechanism of the National Electronic Identity (E-Id) Cards, in our case the Portuguese E-Id card or Cart&227;o de Cidad&227;o (CC). We shall present a comparison of authentication mechanisms and access to popular cloud storage providers, comparing the different authentication mechanisms OAuth 1.0, OAuth 1.0a and OAuth 2.0. Using the proposed architecture we have developed an implementation of this architecture that provides a uniform web based access to popular Cloud Storage Service Providers such as Drop box, Skydrive, Cloudpt and Google Drive using the authentication mechanism of the E-Id card as a unique access token. In order to provide a uniform access to these services we shall describe the differences in the various REST APIs for the targeted providers. Finally the web application that allows users that hold E-Id cards a single point of access to their various cloud storage services will be presented.

No abstract available.

Abstract We present methodological and technological solutions for evolving large‐scale software systems. These solutions are based on many years of research and experience in developing systems in one of the most volatile application domains—banking. We discuss why ‘promising’ software development techniques, such as object‐oriented and component‐based approaches, on their own, cannot meet the challenges and objectives of software development today, and propose a three‐layered architectural approach based on the strict separation between computation, coordination and configuration. We present a set of modelling primitives, design principles and support tools through which such an approach can be put effectively into practice, and discuss how it promotes a more ‘dynamic’ approach to software evolution. Finally, we make comparisons with related work. Copyright © 2002 John Wiley & Sons, Ltd.

Recent advances in telecommunication technology, including wireless networks and the Internet, along with the competition of network operators for offering advanced and different services, are putting increasing pressure for building telecommunication software systems that are adaptive to new requirements and easily reconfigurable, even in run time. We propose a new modelling primitive - coordination contract - that we have developed and applied to other applications domains, as a means to provide an effective solution to this problem. We briefly describe coordination contracts and discuss how they can support the evolution of the specifications of the Wireless Application Protocol (WAP) Datagram layer.