Volume 66 (2015): Issue 1 (January 2015)

Model Reference Controller (MRC) for contribution of Variable Speed Wind Generators (VSWG) in inertial response of Electrical Power System (EPS) is presented and analyzed in this paper. MRC is synthesized based on a model of Generating Unit With non-Reheat Steam Turbine (GUNRST) thus enabling VSWG to emulate GUNRST response during the initial stage of dynamic frequency response ie inertial phase. Very important property of conventional steam generating units is that its contribution to inertial phase response is independent from the initial generating power. By using MRC in VSWG it is accomplished that in most common wind speed region (3-12 m/s) VSWG inertial support is almost independent from wind speed. Since in most EPSs VSWG replaces conventional steam generators, application of MRC algorithm provides that the characteristics of EPS in terms of inertial response are preserved, regardless of the growing trend of introducing VSWG. Evaluation analysis of the proposed MRC is performed on modified nine bus power system when VSWG with MRC is connected to one of the power system buses.

A new realization of RMS detector, employing two CCCIIs (controlled current conveyors), metal-oxide-semiconductor transistors and single grounded capacitor is present in this paper, without any external resistors and components matching requirements. The proposed circuit can be applied in measuring the RMS value of periodic, band-limited signals. The proposed circuit is very appropriate to further develop into integrated circuits. The errors related to the signal processing and errors bound were investigated and provided. To verify the theoretical analysis, the circuit PSpice simulations have also been included, showing good agreement with the theory.

A novel methodology is proposed for robust gain-scheduled PID controller design for uncertain LPV systems. The proposed design procedure is based on the parameter-dependent quadratic stability approach. A new uncertain LPV system model has been introduced in this paper. To access the performance quality the approach of a parameter varying guaranteed cost is used which allowed to reach for different working points desired performance. Numerical examples show the benefit of the proposed method.

The presented paper shows a new concept of multi-slot coaxial antenna working at different frequencies to predict the best solution for interstitial microwave hyperthermia treatment. The described method concerns a microwave heating of unhealthy cells using a thin microwave antenna located in the human tissue. Therefore, the coupled wave equation in a sinusoidal steady-state and the transient bioheat equation under an axial symmetrical model are considered. The 4-Cole-Cole approximation has been used to compute the complex relative permittivity of the human tissues at different antenna operating frequencies. At the stage of numerical simulation the finite element method (FEM) is used. Special attention has been paid to estimate the optimal antenna parameters for thermal therapy for three microwave frequencies mainly used in medical practice and make comparison of the obtained results in the case of single-, double- and triple-slot antennas.

The electrical DC conductivity is measured at room and elevated temperatures on green ceramic samples prepared from kaolin. The arrangement of the sample, with two platinum wire electrodes inserted in the kaolin prism that was used is suitable for measurements of temperature dependences of the DC conductivity from 20 °C to 1100 °C in the air. The uncertainty analysis taking into account thermal expansion of the sample, homogeneity of the temperature field, measurement regime, corrosion of the electrodes, and overlapping of the electrodes is done for 1000 °C. Uncertainties connected with current and voltage measurements and uncertainties connected with the instruments that were used are also considered. The sum of all the partial uncertainties gives an expanded uncertainty of the conductivity measurement. The uncertainty varies with temperature and reaches the value of ∼ 6.5% at 1000 °C.

The method of genetic algorithms is used to optimize the efficiency factor of two objects: single a phase shaded pole motor and the main inductor for an LCL filter, aimed for independent operation. By varying the construction parameters, three motors and two inductor models have been designed and optimized. The optimized motors exhibited a gradual increase of the efficiency factor achieved for the same input power. Also an increased output power has been achieved, which considerably improved the low efficiency factor for this type of the motor. The optimized filter models have an increased efficiency due to the lower losses and a decreased warm-up. All models are evaluated by the finite element method, which allows to plot the magnetic flux density distribution in the cross section and hereby the possible weak parts of the construction with a high flux density can be discovered.

The Internet of Things (IoT) is a technological revolution that represents the future of computing and communications. One of the most important challenges of IoT is security: protection of data and privacy. The SSL protocol is the de-facto standard for secure Internet communications. The extra energy cost of encrypting and authenticating of the application data with SSL is around 15%. For IoT devices, where energy resources are limited, the increase in the cost of energy is a very significant factor. In this paper we present the energy efficient SSL protocol which ensures the maximum bandwidth and the required level of security with minimum energy consumption. The proper selection of the security level and CPU multiplier, can save up to 85% of the energy required for data encryption.

The contribution deals with the comparison of possibilities of utilizing two experimental methods: digital and classical holographic interferometry for the visualization of beam motion. The girders are used in civil and mechanical engineering and considering the technical point of view it is necessary to learn to what extent the beam is deformed at the load and how much it can withstand.

Markers for imaging are vital parts of surgical processes. Since radioactive compound pose considerable risk to both the recipient and the surgical staff, alternative marking techniques are of interest. In NANOMAGDYE project, magneto-optically active nano-particles were created for this reason. The detection of the magnetic interaction of low mass nano-particles in surgical environment is very challenging; so far only quasi-stationary measurements were taken. This paper shows a measurement setup for measurements with continuously moving probe at lower velocities (5–10 mm/s) and at hand movement velocity (20–30 cm/s). It was found that at the velocity of hand movement there is only probe response amplitude reduction of at most 10–15% of the original amplitude. These results indicate that the probe used for the detection of the nano-particles is sufficient to be used in practical purposes in surgery.