Current Issue : July - September Volume : 2014 Issue Number : 3 Articles : 4 Articles
In this paper a knowledge representation approach of an adaptive and/or personalized tutoring system is\npresented. The domain knowledge should be represented in a more realistic way in order to allow the adaptive\nand/or personalized tutoring system to deliver the learning material to each individual learner dynamically taking\ninto account her/his learning needs and her/his different learning pace. To succeed this, the domain knowledge\nrepresentation has to depict the possible increase or decrease of the learner�s knowledge. Considering that the\ndomain concepts that constitute the learning material are not independent from each other, the knowledge\nrepresentation approach has to allow the system to recognize either the domain concepts that are already partly or\ncompletely known for a learner, or the domain concepts that s/he has forgotten, taking into account the learner�s\nknowledge level of the related concepts. In other words, the system should be informed about the knowledge\ndependencies that exist among the domain concepts of the learning material, as well as the strength on impact of\neach domain concept on others. Fuzzy Cognitive Maps (FCMs) seem to be an ideal way for representing graphically\nthis kind of information. The suggested knowledge representation approach has been implemented in an\ne-learning adaptive system for teaching computer programming. The particular system was used by the students of\na postgraduate program in the field of Informatics in the University of Piraeus and was compared with a\ncorresponding system, in which the domain knowledge was represented using the most common used technique\nof network of concepts. The results of the evaluation were very encouraging....
A three-dimensional matrix method is proposed in this paper for Global Navigation Satellite System (GNSS) constellation\nIntrasatellite Link (ISL) topological design.Therows and columns of proposedmatrix contain the information of both constellation\norbit planes and satellites in each orbit plane. The third dimension of proposed matrix represents the time sequences during\nconstellation movement. The proposed method has virtues of better advantage of conceptual clarity and computational efficiency,\nmeanwhile, some properties of ISLs in the constellation can be proved easily. At the second part of this paper, a link assignment\nand optimal routing problem is proposed using three-dimensional topology matrixes, which aimed to minimize the relay hops\nduring the process of data uploading to whole constellation network. Moreover, some practical constrains as antenna beam\ncoverage and relative velocity are considered and analyzed in detail. Finally, some numerical simulations are provided, and the\nresults demonstrated the promising performance of proposed topological method in reduction of computation burden, clear ISL\nconception, and so forth; the efficiency of provided optimal ISL routing problem is also proved....
In this study, we propose an indoor navigation system that utilizes visible light communication technology, which\nemploys LED lights and a geomagnetic correction method, aimed at supporting visually impaired people who\ntravel indoors. To verify the effectiveness of this system, we conducted an experiment targeting visually impaired\npeople. Although acquiring accurate positional information and detecting directions indoors is difficult, we\nconfirmed that using this system, accurate positional information and travel direction can be obtained utilizing\nvisible light communication technology, which employs LED lights, and correcting the values of the geomagnetic\nsensor integrated in a smartphone....
Radio frequency interference detection and mitigation are becoming of paramount importance due to the increasing number of\nservices and applications based on the position obtained by means of Global Navigation Satellite Systems. A way to cope with such\nthreats is the implementation in the receiver of advanced signal processing algorithm able to raise proper warning or improve the\nreceiver performance. In this paper, we propose a method based on theWavelet Transform able to split the useful signal from the\ninterfering component in a transformed domain. The wavelet packet decomposition and proper statistical thresholds allow the\nalgorithm to show very good performance in case of multiple pulse interference as well as in the case of narrowband interference,\ntwo scenarios in which traditional countermeasures might not be effective....
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