Ioannis O. Vardiambasis

Photonics Laboratory Education with a Research-Oriented Approach

In this paper, the content of two laboratory courses developed at the Department of Electronics of the Technological Educational Institute of Crete, Greece, focused on optoelectronics and optical communications, respectively, is presented. Both of these laboratory courses were developed with the philosophy of introducing a research-oriented approach. Emphasis is given on hands-on experimentation. In such a way, students get a better understanding of the various theoretical concepts (generation of light through single mode continuous wave lasers, transmission of optical power, etc.), and become able to analyze and solve problems associated with photonics components and their integration to optical systems. Coupling of experimentation and research is facilitated with a Marie Curie EU-funded grant for the establishment of a Centre of Excellence via the transfer of knowledge in the scientific area of optoelectronics and lasers. Our approach is presented by referring to specific laboratory exercises, such as the experimental study of a variable optical attenuator developed for research purposes, the development of an X-ray high power x-pinch optoelectronic device, etc

Neural network solution of the circular loop antenna radiation problem

The circular cylindrical antenna is a simple, inexpensive, versatile, and very popular antenna type, which has received much attention due its wide range of applications. The exact values of the radiated near and far electromagnetic fields have recently been analytically evaluated, in terms of complex series involving Legendre functions of the second kind and half-integral order. The inverse problem of determining the loop antenna parameters (radius and current) causing specific field levels at one or more points of interest is even more complex. In order to find the solution, avoiding the associated lengthy and time-demanding mathematical analysis, we apply artificial neural network modeling. The proposed models consist of a feedforward back-propagation and a radial basis neural network trained with theoretical data. The results obtained are found to be in perfect agreement with the exact theoretical data.

Needs and Examination of Strategies for Lifelong Learning in Engineering Education

The shortage of highly qualified engineers in our knowledge-based economy requires the collaborative and coordinated action of academic institutions, professional societies, industry players, and education policy makers. In particular, lifelong learning of engineers is considered as one of the most important presumptions for future growth and social welfare. The aim of this paper is to identify the needs for lifelong learning of Greek engineers, based on recent survey data publicly available by the Technical Chamber of Greece. Furthermore, we assess the approach followed by the Department of Electronics of the Technical Educational Institute of Crete (TEloC) in response to the demand for problem-based education in telecommunications and network engineering. This approach, as well as the experience gained from other actions carried out by TEloC (i.e., the establishment of a unit for lifelong learning, the organization of summer schools in hot areas of engineering, workshops offered to the academic instructors), present to be efficient strategies for lifelong learning education.

Development of the RF Front-end of a Multi-Channel Microwave Radiometer for Internal Body Temperature Measurements

Microwave Thermograph (MT) is based on measuring the electromagnetic field spontaneously emitted by a body in micro-wave frequency range. In microwave radiometers, temperature measurement is made by measuring the thermal noise power. The primary module that is used for detecting this thermal noise power is the RF Front-end, which must meet very challenging requirements in terms of accuracy for measuring the noise power at the input of the receiver. The work that will be presented here will exhibit the design approaches and specifications as well as the trade-offs and performance criteria towards the development and prototyping of the RF Front-end for a Multi-Channel Microwave Radiometer for internal body temperature measurements in the l-4GHz frequency bands. The RF Front-end is intended to be integrated and be a part of a full Microwave Radiometer device that targets early detection of malignant tumours. The latter relate with the increase of temperature in cancerous cells and the precise detection of the temperature difference, which is the goal of the radiometer.

Solving the inverse loop antenna radiation problem using a hybrid neuro-fuzzy system

This work presents an alternative method, based on artificial techniques, to manipulate the direct and inverse problems of circular loop antenna radiation, using data extracted from their analytical solutions. The adaptive network fuzzy inference system (ANFIS) has been used, as a basis for constructing a set of fuzzy rules with appropriate membership functions in order to obtain the theoretical data. The numerical results for both problems are found to be in excellent agreement with the exact theoretical values.

Strengthening the University-Industry Relationship: A Case Study of the Electronics Department, TEI Crete.

The Department of Electronics of the Technological Educational Institute of Crete (DoE/TEI Crete) enjoys good approval ratings from the market and its graduates have a high rate of employability. However, survey data collected over the last ten years from graduates and from the enterprises in which they have been employed, or have carried out their workplace learning, indicate the strong and weak aspects of the Departments curriculum from the viewpoint of the job market. The authors identify issues that may improve the access of their graduates to the market and which may also bring enterprises closer to the DoE, thus offering both parties the opportunity to establish internships for research. It is proposed that the time is now right for a next step to be made towards achieving cooperative engineering education and the authors offer suggestions as to how this might be achieved.

Propagation in Cylindrical Inset Dielectric Guide Structures

The inset dielectric guide (IDG) is just a rectangular groove filled with dielectric, which retains many of the advantages of dielectric guides, without fabrication and loss problems. Quasi-planar IDGs are attractive for applications in microwave and millimeter-wave frequency ranges, as they can be used as low loss and low cost transmission lines, directional couplers, nonreciprocal phase shifters, antennas and other devices. In this paper we address circular IDG-type structures, investigating hybrid wave propagation in single microslot lines loaded with semi-circular dielectric cylinders. The analysis is based on systems of singular integral-integrodifferential equations of the first kind. The proposed algorithms are rapidly convergent, yielding very accurate results for the propagation constants and for the modal equivalent magnetic currents of the principal as well as the higher-order modes.