DGD Gallery: Storage, sharing, and publication of digital research data

We describe a project, called the "Discretization in Geometry and Dynamics Gallery", or DGD Gallery for short, whose goal is to store geometric data and to make it publicly available. The DGD Gallery offers an online web service for the storage, sharing, and publication of digital research data.Comment: 19 pages, 8 figures, to appear in "Advances in Discrete Differential Geometry", ed. A. I. Bobenko, Springer, 201

A Vernacular for Coherent Logic

We propose a simple, yet expressive proof representation from which proofs for different proof assistants can easily be generated. The representation uses only a few inference rules and is based on a frag- ment of first-order logic called coherent logic. Coherent logic has been recognized by a number of researchers as a suitable logic for many ev- eryday mathematical developments. The proposed proof representation is accompanied by a corresponding XML format and by a suite of XSL transformations for generating formal proofs for Isabelle/Isar and Coq, as well as proofs expressed in a natural language form (formatted in LATEX or in HTML). Also, our automated theorem prover for coherent logic exports proofs in the proposed XML format. All tools are publicly available, along with a set of sample theorems.Comment: CICM 2014 - Conferences on Intelligent Computer Mathematics (2014

Reconfigurable phased microstrip antenna array with defected ground structure and defected microstrip structure for beam steering application

Beam steering is defined as the ability to electronically steer the beam maximum of an antenna electric field pattern to some predefined point in space. The performance of a phased antenna array for beam steering without moving the antennas is important to military and civil applications. A steerable antenna with tunable phase shifter continues to be a popular choice to provide such systems. However, this additional device makes the structure more complicated, bulky and it represent a great part of the production cost of a phased array antenna. Therefore, it creates new challenges to find an alternative approach. This work proposed two alternative approaches to steer the main beam. The first is based on a defected ground structure (DGS), while the second is a defected microstrip structure (DMS), which due to their slow wave effect and band-stop property, are able to disturb surface current distribution, then change the element phase and hence steer the main beam. This work started with investigating and applying new method for beam steering based on using DGS and DMS, where this reflects the first objective. As a second objective, this work proposed new approach for beam steering, where DGS is integrated between two patches for the bandwidth within X-band. The simulated results revealed the achievement of the target to steer the main beam to 50° along H-plane. For the third objective, a spiral antenna array (SAA) has been proposed, and it was observed that the best choice for selecting feed network for feeding circular antenna array is a common sequential feed network (SFN), which has a circular shape with four ports to feed four elements. In order to increase the number of ports and hence design suitable feed network for feeding SAA, this study proposed new spiral sequential feed network (SSFN). As a dual structure of DGS, and compared with DGS, DMS is of great advantage in design due to its reduced size and the feature of electromagnetic interference noise immunity. Furthermore, DMS has higher effective inductance compared to DGS. Therefore, this work proposed new reconfigurable SAA with DMS fed by SSFN within C-band. The simulated results showed the achievement of the target to steer the main beam to 61° and 84° along E-plane and H-plane, respectively. Furthermore, as the last objective, a new approach was proposed for extracting equivalent circuit model for DGS with dual patches, SSFN and SAA. Two prototypes of dual patches with and without DGS, SSFN and two prototypes of SAA with DMS were fabricated for scattering parameter and far-field radiation pattern measurements. The results showed close agreement with the predicted results, where array with DGS confirmed a beam steering of 36° along H-plane, while SAA with DMS displayed 45° beam steering along E-plane, respectively. Future works will focus on increasing the array gain and reducing the array beam width which will give a clear vision for beam steering of array

Visual exploration and retrieval of XML document collections with the generic system X2

This article reports on the XML retrieval system X2 which has been developed at the University of Munich over the last five years. In a typical session with X2, the user first browses a structural summary of the XML database in order to select interesting elements and keywords occurring in documents. Using this intermediate result, queries combining structure and textual references are composed semiautomatically. After query evaluation, the full set of answers is presented in a visual and structured way. X2 largely exploits the structure found in documents, queries and answers to enable new interactive visualization and exploration techniques that support mixed IR and database-oriented querying, thus bridging the gap between these three views on the data to be retrieved. Another salient characteristic of X2 which distinguishes it from other visual query systems for XML is that it supports various degrees of detailedness in the presentation of answers, as well as techniques for dynamically reordering and grouping retrieved elements once the complete answer set has been computed

A dataflow platform for applications based on Linked Data

Modern software applications increasingly benefit from accessing the multifarious and heterogeneous Web of Data, thanks to the use of web APIs and Linked Data principles. In previous work, the authors proposed a platform to develop applications consuming Linked Data in a declarative and modular way. This paper describes in detail the functional language the platform gives access to, which is based on SPARQL (the standard query language for Linked Data) and on the dataflow paradigm. The language features interactive and meta-programming capabilities so that complex modules/applications can be developed. By adopting a declarative style, it favours the development of modules that can be reused in various specific execution context

Migrating existing multimedia courseware to Moodle

Open source course management systems offer increased flexibility for instructors and instructional designers. Communities can influence the development of these systems and on an individual basis, the possibility to modify the system software exists. Migrating existing courseware to these systems can therefore be beneficial, sometimes even required. We report here about our experience in migrating an existing courseware system consisting of multimedia content and interactive, integrated infrastructure functionality to an open source course management system called Moodle. We will assess the difficulties that we have encountered during this process and, discuss the importance of standards in this context, and we aim to provide other instructors or instructional designers with guidelines and assessment support for other migration projects

CVcat: an interactive database on cataclysmic variables

CVcat is a database that contains published data on cataclysmic variables and related objects. Unlike in the existing online sources, the users are allowed to add data to the catalogue. The concept of an ``open catalogue'' approach is reviewed together with the experience from one year of public usage of CVcat. New concepts to be included in the upcoming AstroCat framework and the next CVcat implementation are presented. CVcat can be found at http://www.cvcat.org.Comment: 5 pages A&A Latex, 4 figures, accepted for publication in A&