Sotirios Kontogiannis

Homogeneity and Enrichment: Two Metrics for Web Applications Assessment

This paper presents a digital controlled distributed converter system with a switched-mode boost type PWM rectifier and several bidirectional buck/boost dc/dc converters for battery charge and discharge system using digital signal controller (DSC). The rectifier can implement bidirectional power flow, sinusoidal current control and unit power factor in grid side. The system is able to control power flow between the ac supply and dc side, or within the dc side. It is significant in development of green, economizing energy equipments. Simulation and experimental results are shown to verify the proposed distributed control scheme.Earlier studies suggest that educational institutions may further benefit from Learning Management Systems (LMSs) by generating reports regarding courses. That is, with the use of tools focus to assess students paths into course content. This paper affirms that educational meaningful information can be extracted from LMS student logged data and presents a methodology on how such findings may assist to the development of a reporting tool for educators. In the context of course assessment from student logged data, we introduce a new metric called homogeneity that extends the use of an older one, enrichment. We also propose a new algorithm that tries to qualify course content by classifying the course based on students’ course paths interest. We applied our algorithm to Open eClass LMS tracking data of an academic institution and we present the results identified in 12 courses along with interest insights. We leave for future development the creation of an automated tool of our algorithm implemented for the Open eClass platform.

E-Learning Activity Analysis

Abstract Nowadays, web-based educational systems are being installed more and more by universities, schools, businesses, and even individual instructors in order to add web technology to their courses and to supplement traditional face-to-face courses. These systems accumulate a vast amount of data which is very valuable for analyzing the contentof the courses and their usage from the learners. A new method is proposed in order to analyze these datain three layers based on an innovative organization. Seven variables are used.They are combined properly to quantify quality characteristics of the courses and offer useful insights based on their material and usage by the learners. All the variables were put to test in a case scenario that took place in a Greek university web based e-Learning data. The evaluation of the results has shown that the proposed system managed to track both educational content and course usage successfully. The results confirmed the validity of the approach and showed a relationship among the components of the proposed 3-layer organization.

Course Ranking and Automated Suggestions through Web Mining

This paper introduces new metrics for course evaluation. It is also proposes a ranking algorithm that classifies courses based on the previous course evaluation metrics and suggests appropriate actions for course content improvement. The algorithm was tested and verified successfully in data originated from the eClass platform of TEI Kavala.

Proposed cloud infrastructure of wearable and ubiquitous medical services

A Wearable Health Monitoring system is described that uses low-cost off the shelf sensors and computing components, along with custom made software, to provide an economical solution to personalized health care monitoring problems, while retaining all the functionality and flexibility of more expensive systems. Cloud technology is used to store sensor measurements which are categorized based on the criticality of bio-signals. Furthermore, a new session protocol for medical sensor data transmission is proposed. In a prototype system, tests based on different transmission architectures have so far yielded useful and favorable results in comparison with existing protocols and usually more expensive systems.

A Survey of Transport Protocols for Haptic Applications

The term Hap tic refers to the sense of touch. The feeling has the ability to increase the sense of reality, to excite the user and improve the quality of experience. To carry out this sense through the Internet was, until recently, impracticable due to processing inefficiencies and/or protocol performance in capabilities, such as throughput and jitter constraints. This paper describes a Hap tic system architecture. Moreover it presents a survey of transport protocols for hap tic applications. It also performs a classification of related protocol capabilities and outlines the flow requirements that should be met by protocols designed to carry such data.

ALBL: an adaptive load balancing algorithm for distributed web systems

This paper presents an adaptive load balancing algorithm (ALBL) for cluster-based web systems. The balancing policy is based on two criteria: HTTP process time and network delay. The former describes web server ability to process a forthcoming request, while the latter tries to estimate network conditions. Periodic criteria calculations are performed by agents at the web switch and the weight estimation process is transparent to web servers enhancing therefore distributed systems scalability. We put to test our implementation against known blind selection balancing algorithms used at web-farms such as: Round Robin, stateful ones such as Least Connections and adaptive ones such as Least Load. We also put to test performance and scalability of previous algorithms. From our testbed scenario results we show that ALBL algorithm outperforms stateless and stateful algorithms and also presents significant performance gains towards adaptive algorithms. We also show that our algorithm scales well as the number of balancing servers and web clusters requests rate increases. We also pinpoint ALBL algorithm ability to predict network conditions and web servers load without the use of feedback information obtained by web servers but frequent service and network probes towards web servers issued by the web switch.

Evaluating transport and application layer protocols for haptic applications

Recently, a number of transport and application layer protocols for haptic and Interactive applications have been proposed. This paper presents a survey of the above protocols. It outlines the haptic data transmission characteristics. It also depicts the qualitative features that transport and application layer protocols should contain in order to carry haptic data. Based on these criteria, evaluation of the above protocols is performed.

A Combined Algorithm for LMS Usage Assessment

LMS are used more and more nowadays. There are some algorithms for LMS usage assessment. The main problem is that these algorithms are rarely combined. This gap can be filled by using S-Algo which combines ranking and suggestion results of two or more suggestion/ranking algorithms into an ultimate and efficient ranking suggestion. Such efficient ranking is based on ranking algorithms used and proposed metrics recorded course attributes. S-algo was applied to Open eClass LMS tracking data of an academic institution. In the context of course assessment from student logged data, two existing algorithms called SUGAL and CCA as ranking/suggestion algorithms were selected. Then, on the results provided from these algorithms, S-algo tested and confirmed the success of its ranking process.

A Smart IoT Fuzzy Irrigation System

This paper proposes a novel fuzzy computational algorithm for IoT smart irrigation systems. It describes all the possible sensors, actuators and microcontrollers that could be used in the irrigation systems. Based on these sensors a novel system architecture is presented. The irrigation system continuously monitoring air temperature and humidity, and ground moisture. The ground humidity sensors are interspersed all over the field. The measurements are send in a microcontroller that applies a fuzzy computational algorithm and decides whether to open a servo valve or not. All the data collected from the microcontroller are sent to a cloud database for statistical information and processing.

A novel microclimate forecasting system architecture integrating GPS measurements and meteorological-sensor data

It is apparent that local climatic conditions have clear implications for agriculture. For this reason accurate information on local climate dynamics is essential for agricultural planning. This study introduces a methodology that aims to enhance microclimate monitoring through GPS networks. This paper describes this novel approach, its implications and presents some preliminary results. Authors propose a novel implementation of a weather monitoring system comprised of existing geodetic and meteorological sensors cooperative efforts, coordinated by roaming microclimate sensors. Such system shall be utilized for the real-time prediction of crucial and emergent phenomena for the agricultural industry. This system shall offer more accurate predictions with the use of spatial microclimate profiles and water vapor content estimates attained from GPS measures. Furthermore, a new session protocol based on SNMP protocol shall be used for data acquisition and a caster station for post processing and visualization purposes.