Antonios Andreatos

Using Open Educational Resources in Course Syllabi

Abstract The purpose of this article is (1) to review the advantages of using learning objects (LOs) and open educational resources (OER), (2) to propose the enrichment of course syllabi with LOs/OER, (3) to propose new fields to be included in metadata and ways for embedding metadata in LOs/OER, (4) to review the problem of lack of metadata in Web 2.0 sites, and (5) to propose a method for populating a detailed course syllabus with OER. For this purpose, the authors have developed an experimental tool called LO Finder.

On the Definition and Impact of Virtual Communities of Practice

The evolution of the Internet has made several Communities of Practice to go online and has brought into life numerous Virtual Communities of Practice. The purpose of this article is: to define and categorize Virtual Communities of Practice; to examine their social impact in general and specifically in knowledge and technology management; also, to examine the contribution of Communities of Practice to informal learning and to relate them to Connectivism and collaborative learning. Several case studies are presented to clarify the presentation. It is expected that Virtual Communities of Practice will play an important role in both learning theory and practice as well as knowledge management during the years to come.

A Stegosystem with Advanced Security Features - Simulated in Matlab

This paper presents a Steganography Telecom System for data cryptography, based on a Chuas Circuit Chaotic Noise Generator. The cipher text is randomly distributed on a cover image in a stochastic mode. To achieve this innovative feature, we have used a pseudo-random number generator. The whole system presents advanced security features and it is simulated in Matlab. Simulation results which demonstrate the proof of concept are presented.

Electronic Exams for the 21st Century

Information and communication technology (ICT) has deeply affected the way people in modern societies become educated and learn new things. Several “digital skills” are needed for young people in order to live and work in the 21st century. During the years to come, a tremendous development and spread of e-learning, and consequently e-assessment, is expected. Common question types used today will soon prove inadequate to assess the required “digital skills.” In this paper we deal with this problem and we propose some solutions.

Network Traffic Analytics for Internet Service Providers—Application in Early Prediction of DDoS Attacks

In this chapter an approach for modelling intra-values forecasts of a time-series Network Traffic using a mean reverting stochastic process (MRSP) is presented. An autoregressive model of order n, AR(n), formalized in state space, with its unobservable coefficients estimated by a Kalman filter using n past time series observations produces [AR(n)-KF] estimates, which constitute the mean reverting part of the process. A Brownian motion multiplied by a diffusion (or volatility) term constitutes the stochastic part of the process. The determinant and trace of the Kalman filter error covariance matrix multiplied by the process itself is used to capture the diffusion dynamics in the intra-values time-series. The proposed algorithm is designed especially for network traffic and it does not assume stationary data. The method was tested using real traffic data from GRnet concerning our institutional network. Experimental as well as simulation results based on real daily data from the GRnet IP traffic demonstrate the applicability of the model. The proposed MRSP algorithm was able to identify successfully unusual activities contained in the test datasets and produce proper warnings. Applications on real-time D/DoS bandwidth-flooding attack detection, are also presented.

Implementing transistor roles for facilitating analysis and synthesis of analog integrated circuits

In an integrated circuit, transistors are used in standard configurations which occur repeatedly. In order to facilitate circuit analysis and synthesis for students, the concept of ‘transistor role’ has been introduced and a fundamental set of bipolar and MOS transistor roles was defined. This paper presents the LTspice implementation of the Bipolar and MOS Transistor Roles Building Block (BB) Library, with the most common transistor roles. Utilizing this BB Library, we then demonstrate the LTspice implementation of three representative analog integrated circuits: the LM741 Op Amp, the Open Loop CMOS Comparator MC14575 and a composite cascode high gain CMOS Op Amp. Simulation results prove that the transistor roles BB library works as expected, while facilitating circuit analysis, thus, allowing students to synthesize and simulate complex analog circuits more easily.