[Show abstract][Hide abstract] ABSTRACT: Internet Protocol (IP) suite and Ethernet physical layer are the current trend in home and industrial systems communication protocols. Unfortunately, in the field of power line automation protocols that are in wide use in home automation applications, the lack of IP convergence leads to difficulties, because of the variety and high costs of systems and solutions that need to be integrated. This paper presents a simple and reliable convergence mechanism of open power line Home Automation Protocols to IP (HAPoIP), which is implemented and tested for X10 protocol, on a low cost platform. The novelty and the achievement of the proposed system is the integration of heterogeneous automation networks through IP. In addition, the system was built in terms of software and hardware based on a new protocol.
[Show abstract][Hide abstract] ABSTRACT: The Wireless Local Area Networks (WLANs) are often used as a wireless extension to the typical office network infrastructure providing mobility to the users. In addition Wireless Personal Area Networks (WPANs) serve interconnection to computer and mobile phone peripherals as headsets, input devices, printers etc. Thus it is common that WLANs and WPANs have to operate in the same area. IEEE 802.11b/g is the most popular WLAN technology operating in the 2.4GHz Industrial Medical and Scientific (ISM) band. On the other hand Bluetooth (BT) is the technology often used to support WPANs. As BT also uses the 2.4GHz ISM band, there an issue of interference between WLANs and PANs. In this work the performance degradation in Wireless Local Area Networks and Wireless Local Area Networks due to co- existence is examined by real measurements. Both 802.11 to 802.11 and 802.11 to Bluetooth coexistence is addressed.
Full-text · Article · Jun 2009 · Computer Science and Information Systems
[Show abstract][Hide abstract] ABSTRACT: In this paper, a new fault tolerant inverter design is presented, with N+k redundancy and hot-swapping capability. The proposed method uses N+k parallel H- bridges capable of fault detection and isolation. An open collector "fault" signal can be set or control each bridge. A flexible control unit accepts, activates or deactivates the "fault" signals of all the H-bridges. A prototype inverter with four H-bridges and multilevel modulation was constructed and tested in the laboratory to verify the practical problems of the method. The proposed method is mainly intended for non-cascaded inverters.
[Show abstract][Hide abstract] ABSTRACT: In today's globalized economy there is a strong interaction between industry, education, and research and development activities. A good cooperation and interaction between the players involved in the aforementioned activities is necessary. At the same time, new challenges and opportunities are emerging as a consequence of rapidly improving technological capabilities, such as the information and communications technologies. As it concerns higher education institutions, they should respond appropriately in an academic globalized environment, and participate to our knowledge society by the use of information society tools. In such a framework, we propose the exploitation of Web 2.0 technologies (weblogs, wikis, RSS feeds) for the effective workplace learning of students. The implementation of our approach will take place at the final phase of the EPEAEK II project at the Department of Electronics of the Technological Educational Institute of Crete, Greece. Based on our previous experience and assessment data, we are striving to the creation of an e-collaboration environment that will support workplace learning activities of our students and will further promote the cooperation between our Department and the industry partners.
[Show abstract][Hide abstract] ABSTRACT: Electromagnetic Radiation found in a typical building today is an integral part of technology evolution. Electric power distribution networks are present in every building producing time variable magnetic and electric fields in a low frequency range (50 Hz - 100 KHz) commonly named as Extremely Low Frequencies (ELF). On the other hand wireless networks and other high frequency activity, in the range of Radio Frequencies (RF) 100 KHz up to 6 GHz produce ElectroMagnetic Fields (EMF) that radiate in the indoor environment. In this work the potential to take advantage of such electromagnetic pollution to provide power supply to micro-devices (such as wireless sensors) is examined. This is based in real EMF measurements in a typical office environment.
[Show abstract][Hide abstract] ABSTRACT: This paper presents the design and implementation of software for creating test patterns and communicating them to a test platform for electrical appliances as well as the architecture of the testing platform. The software lets the user design different types of voltage fluctuations, repeat and sequence them making testing Series and store them on a PC. The testing Series are communicated with special protocols to the platform. The architecture of the platform consists of a DC/AC inverter that can produce variable frequency and variable voltage up to a maximum voltage level, Spike Production Circuit to produce spikes at levels higher than that of the inverter and electronic relay circuit for switching between the inverter and the Spike Production Circuit. Microprocessors control the inverter, the Spike Production Circuit and the relay in order to produce the desired output waveform to the appliance/device-under-test. The algorithms running on the microprocessors are presented.
[Show abstract][Hide abstract] ABSTRACT: During a computer conference, users desire to view the same computer generated information and displays. This is often accomplished by communicating this information over wideband links to provide real- time displays. A concept was developed for communicating inputs (e.g., keystrokes) instead of outputs (e.g., displays). Techniques were designed to allow two computers to execute the same application program, get the same inputs at the same relative point in their execution, and produce the same outputs. Models were created to describe and analyze the way in which inputs are entered into executing programs. Protocols were written to distribute and synchronize the inputs between the computers. Petri nets were used to validate the synchronization of the inputs. Timing analysis was performed to guarantee simultaneity in execution.
[Show abstract][Hide abstract] ABSTRACT: Many times there are refrigerators and chambers that need to be monitored from a distance. Many reasons may prevent the proper operation of the refrigerator and damage may be caused. A remotely configured, supervisory and data acquisition system for refrigerators is proposed. The design is based on an inexpensive, ultra low power 16-bit RISC microcontroller that implements as many as possible functionalities of the supervisory and data acquisition system. Different type of sensors to monitor the condition of the refrigerator and their interfaces are presented. Communication techniques are analyzed and different designs are presented for data transmission through the telephone line. A microprocessor based design, including hardware and algorithms, is explained. Efficient algorithms were elaborated and their running time on the processor is estimated. The design targets for a reliable and accurate system with reduced power consumption.
[Show abstract][Hide abstract] ABSTRACT: This paper presents the design and implementation of a platform for testing the endurance and behavior of electrical appliances in fluctuations of their input supply voltage. The proposed platform design produces similar voltage fluctuations as the power network. The platform that is presented, uses a DC/AC inverter that can produce variable frequency and variable voltage up to a maximum voltage level. A Spike Production Circuit is added to the design to produce spikes at levels higher than that of the inverter. An electronic relay circuit is responsible for switching between the inverter and the Spike Production Circuit. The inverter, the Spike Production Circuit and the relay are microprocessor controlled in order to produce the desired output waveform to the Device Under Test. The platform is interfaced with a PC where an application program was developed in order different testing patterns to be able to be generated and stored. This way the platform will have the ability to cause electrical distress at the appliance in a programmable and repeated fashion. Results are presented.
[Show abstract][Hide abstract] ABSTRACT: Vehicles need to monitor different parameters while traveling and report them to a Base Station. Many parameters do not have to be presented to the Base real time. This information can be communicated with RF when vehicle is in proximity with the Base. A protocol was designed targeted for this purpose and was mplemented using polling mechanism. Analysis and performance on the protocol is presented.
[Show abstract][Hide abstract] ABSTRACT: Distributed control and energy management for buildings is a viable solution, ensuring both indoor comfort for the occupants and reduction of energy consumption. The aim of this paper is to present the architecture of a distributed building energy management system that can be installed in new as well as in existing buildings, which are more energy inefficient. The system integrates a smart card unit, acting as a user machine interface, sensors, actuators, interfaces, a PLC controller that incorporates the fuzzy control algorithm, local operating network (LON) modules and devices and an optional PC which monitors the performance of the system. The distributed control architecture is based on the properties of the LON. The complete system is installed and tested in the Laboratory of Electronics of the Technical University of Crete.
Full-text · Article · Jan 2002 · Energy Conversion and Management
[Show abstract][Hide abstract] ABSTRACT: The aim of this paper is to present and evaluate control strategies for adjustment and preservation of air quality, thermal and visual comfort for buildings’ occupants while, simultaneously, energy consumption reduction is achieved. Fuzzy PID, fuzzy PD and adaptive fuzzy PD control methods are applied. The inputs to any controller are: the PMV index affecting thermal comfort, the CO2 concentration affecting indoor air quality and the illuminance level affecting visual comfort. The adaptive fuzzy PD controller adapts the inputs and outputs scaling factors and is based on a second order reference model. More specifically, the scaling factors are modified according to a sigmoid type function, in such a way that the measured variable to be as closer as possible to the reference model. The adaptive fuzzy PD controller is compared to a non-adaptive fuzzy PD and to an ON–OFF one. The comparison criteria are the energy required and the controlled variables response. Both, energy consumption and variables responses are improved if the adaptive fuzzy PD type controller is used. The buildings’ response to the control signals has been simulated using MATLAB/SIMULINK.
Full-text · Article · Jul 2001 · Energy and Buildings
[Show abstract][Hide abstract] ABSTRACT: This paper presents the design and implementation of a spike production circuit for testing the endurance and behavior of electrical appliances in fluctuations of their input supply voltage. The proposed spike production circuit produces voltage spikes up to 1KV with high slew rate. The spike production circuit uses an AC/DC converter that can produce variable voltage up to a maximum voltage level. This voltage charges a variable capacitance in a capacitor bank. An electronic relay circuit is responsible to switch the electrical appliance to the output of the Spike Production Circuit. The spike production circuit is interfaced with a PC where a control program was developed to set and control the spike production circuit. Experimental results are presented.
[Show abstract][Hide abstract] ABSTRACT: This paper traces some of the main factors that influence the Higher Education. The investigated parameters are a) the qualifications of the academic staff, b) the variety of modern research fields of the institution, and c) the course structure of the Departmental curriculum. The second aim of this survey is to connect the education quality of the graduates with their employment opportunities. High quality education results are a) the high employment rate of the graduates, b) the number and quality of the possible employers and c) the number of graduates that continue their studies to postgraduate level. The survey was performed at the Department of Electronics of the Technological Educational Institute (TEI) of Crete in Chania and results from the analysis of a questionnaire report that was sent to the graduate students of the Department.