Showing papers in "Journal of Electrical Engineering-elektrotechnicky Casopis in 2015"

Multi–Frequency Analysis For Interstitial Microwave Hyperthermia Using Multi–Slot Coaxial Antenna

Abstract: 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.

Water Cycle Algorithm Based Power System Stabilizer Robust Design for Power Systems

Abstract: Abstract Power System Stabilizers (PSSs) are used to enhance damping of power system oscillations. This paper presents a new fast algorithm to develop PSS. According to this regard, Water Cycle Algorithm (WCA) is used to detect optimum Power System Stabilizer parameters. For this purpose, the design problem of PSS is formulated as an optimization problem and WCA by forming three subsidiary objective functions is employed to search for optimal power system stabilizer’s parameters to minimize the maximum overshoot and settling time together. In order to show the efficiency of the proposed algorithm, a comparison between WCA and without PSS condition has been done, and the results of proposed algorithm show that it detects optimum parameters in reasonable computation time to increase the power system stability.

A robust approach for acoustic noise suppression in speech using anfis

Abstract: The authors of this article deals with the implementation of a combination of techniques of the fuzzy system and artificial intelligence in the application area of non-linear noise and interference suppression. This structure used is called an Adaptive Neuro Fuzzy Inference System (ANFIS). This system finds practical use mainly in audio telephone (mobile) communication in a noisy environment (transport, production halls, sports matches, etc). Experimental methods based on the two-input adaptive noise cancellation concept was clearly outlined. Within the experiments carried out, the authors created, based on the ANFIS structure, a comprehensive system for adaptive suppression of unwanted background interference that occurs in audio communication and degrades the audio signal. The system designed has been tested on real voice signals. This article presents the investigation and comparison amongst three distinct approaches to noise cancellation in speech; they are LMS (least mean squares) and RLS (recursive least squares) adaptive filtering and ANFIS. A careful review of literatures indicated the importance of non-linear adaptive algorithms over linear ones in noise cancellation. It was concluded that the ANFIS approach had the overall best performance as it efficiently cancelled noise even in highly noise-degraded speech. Results were drawn from the successful experimentation, subjective-based tests were used to analyse their comparative performance while objective tests were used to validate them. Implementation of algorithms was experimentally carried out in Matlab to justify the claims and determine their relative performances.

Variable structure sliding mode control and direct torque control of wind power generation system based on the pm synchronous generator

Abstract: This paper presents a Variable Structure Sliding Mode Control (VS-SMC) scheme and Direct Torque Control (DTC) for Wind Farm (WF) based on the Permanent Magnet Synchronous Generator (PMSG). The WF consists of a 3 PMSGs which are connected to a common dc bus system with rectifier. The dc-bus is connected to the electrical network using only one inverter system, a grid-side filter as well as the transformer. The efficiency of the WF can be greatly improved using an appropriate control approach. So, the control strategy uses the technique of DTC to regulate the speeds of PMSGs for Maximum Power Point Tracking (MPPT) mode. Besides, by employing VS-SMC the grid-side inverter is controlled to inject the generated power into the electrical network, to regulate DC-link voltage and to achieve Unity Power Factor. The used control strategies provide an optimal control solution for WF systems based on the PMSG. K e y w o r d s: wind power generation system, PMSG, MPPT, VS-SMC, DTC, unity power factor

Design And Rotor Geometry Analysis Of Permanent Magnet-Assisted Synchronous Reluctance Machines Using Ferrite Magnet

Abstract: Abstract Various electric machines can be the candidate for electric vehicles applications, including induction machines, permanent magnet synchronous machines, switched reluctance machines, etc. Another class of machine, which has been relatively ignored, is synchronous reluctance machines. In order to enhance and increase torque density of pure synchronous reluctance machines, the low cost permanent magnet can be inserted into rotor lamination to contribute torque production, which is so-called permanent magnet-assisted synchronous reluctance machines. This paper presents the design and rotor geometry analysis of low cost ferrite permanent magnet-assisted synchronous reluctance machines with transversally-laminated rotor. The advanced finite element method will be employed to calculate d-axis and q-axis inductance variation with rotor geometric parameters. The electromagnetic performance of optimized permanent magnet-assisted synchronous reluctance machines will be evaluated as well.

An Energy Efficient Protocol For The Internet Of Things

Abstract: 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. K e y w o r d s: information security, computer networks, cryptography, energy consumption

Nonlinear Predictive Control of Wind Energy Conversion System Using Dfig with Aerodynamic Torque Observer

Abstract: In order to improvement of the performances for wind energy conversions systems (WECS), an advanced control techniques must be used. In this paper, as an alternative to conventional PI-type control methods, a nonlinear predictive control (NPC) approach is developed for DFIG-based wind turbine. To enhance the robustness of the controller, a disturbance observer is designed to estimate the aerodynamic torque which is considered as an unknown perturbation. An explicitly analytical form of the optimal predictive controller is given consequently on-line optimization is not necessary The DFIG is fed through the rotor windings by a back-to-back converter controlled by Pulse Width Modulation (PWM), where the stator winding is directly connected to the grid. The presented simulation results show a good performance in trajectory tracking of the proposed strategy and rejection of disturbances is successfully achieved. K e y w o r d s: nonlinear predictive control, DFIG-based wind turbine, disturbance observer

Control of Photovoltaic Water Pumping System

Abstract: Due to the continuous decrease of the solar cells cost, photovoltaic energy is used in different applications. The most important one is the water pumping system powered by photovoltaic generators. These systems can work with or without storage battery. With the increased use of this application, more attention has been paid to their optimum utilization. Many methods have been developed to determine the maximum power point (MPP). In this paper, to control the DC bus voltage, we apply field oriented control (FOC) strategy to induction motor (IM) supply by a photovoltaic (PV) system. And to maximize the efficiency of the proposed PV pumping system, we use the fuzzy logic controller (FLC) and the classical Perturb and Observ (P&O). Different tests have been carried to prove the effectiveness of the proposed control system. KeywordsPumping Photovoltaic system, Fiel oriented contorl, MPPT, Fuzzy logic controlle, Perturb and Observ .

A Reinforcement Routing Algorithm with Access Selection in the Multi-Hop Multi-Interface Networks

Abstract: In this paper, a routing algorithm is proposed for access selection in a network to find the optimal paths among intermediate nodes with multiple interfaces. Markov Decision Process is applied in each node to find optimal policy and select proper paths to the best access point in a dynamic environment. A reward function is defined as environment feedback to optimize and adapt routing behavior of nodes based on the local information. Selection metrics in each node are interface load, link quality and destination condition. It is shown, by using the proposed algorithm, there are better management in the node which decreases interference and collision and selects links with better quality toward the best possible destination. The performance of the method is exemplified and it is shown how the throughput and average delay of the network with more interface in its nodes, improved while packet loss degrades. As an example a two-interface and a one-interface network are studied. It is shown when network load is increased, interface management will improve the throughput, in the network with two-interface nodes. Also, by considering the link quality factor in the reward function, packet dropping becomes less but average delay increases.

A New System For Measuring The Deflection Of The Beam With The Support Of Digital Holographic Interferometry

Abstract: Due to the external forces activity the solids change their shape — they deform. The deformations can be flexible (temporary), by which the solid regains its original shape after the force activity is finished, and inflexible, by which the solid does not regain its original shape and the force activity consequences are of permanent character. The solid is characterized by the fact that under common conditions it keeps its solidity. This solidity can be impaired by the activity of sufficiently strong forces. After exceeding a specific critical force the solid cannot withstand the load and is distorted (broken, torn, etc). Five simple deformations are distinguished: deformation by tension, compression, bending, shear and torsion. In technical practice we can encounter mainly the deformations comprising several types of simple deformations. The beam is the bearing part of the specific technical piece of work determined for the forces transfer. It is usually a static transfer of the other solids forces activity. The beam is frequent in civil engineering and in the architecture of large buildings as well as it can be found in mechanical engineering in heavy machinery. From the technical point of view it is important to know how the beam is deformed under the load and how much it can withstand.

Uncertainty Of The Measurement Of DC Conductivity Of Eramics At Elevated Temperatures

Abstract: 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.

Discrete-time integral sliding mode control with disturbances compensation and reduced chattering for pv grid-connected inverter

Abstract: In the paper a new discrete-time integral sliding mode control (DISMC) with disturbances compensation and reduced chattering for grid-connected inverter is proposed for active and reactive power regulation. Differently by many SMC proposed in literature that have a time-continuous formulation in spite have been implemented with digital processor, the proposed DISMC is fully formulated in discrete-time, taking into account the effects introduced by a microprocessor-based implementation. As will be demonstrated such approach consents to reduce the chattering about the sliding manifold within a boundary layer of O(T2) thickness instead of O(T) (being T the sampling period of the control algorithm). Moreover it introduces a correction of the control vector which eliminates the influence of modeling error and external disturbances improving stability and robustness of the controlled system. Constant converter switching frequency is achieved by using space vector modulation, which eases the design of the ac harmonic filter. In the paper, after a detailed formalization of the proposed control algorithm, several numerical and experimental results on a three-phase grid-connected inverter prototype are shown, proving the effectiveness of the control strategy. K e y w o r d s: sliding mode control, grid-connected inverter, renewable energy, PV inverter

Text Line Segmentation With Water Flow Algorithm Based on Power Function

Abstract: This manuscript proposes an extension to the water flow algorithm for text line segmentation. Basic algorithm assumes hypothetical water flows under few specified angles of the document image frame from left to right and vice versa. As a result, unwetted image regions that incorporate text are extracted. These regions are of the major importance for text line segmentation. The extension of the basic algorithm means modification of water flow function that creates the unwetted region. Hence, the linear water flow function used in the basic algorithm is changed with its power function counterpart. Extended method was tested, examined and evaluated under different text samples. Results are encouraging due to improving text line segmentation which is a key process stage. K e y w o r d s: optical character recognition, image processing, text line segmentation, water flow algorithm

Impact of low frequency electromagnetic field exposure on the candida albicans

Abstract: Effect of low frequency electromagnetic field on growth of selected microorganism is studied in the article. The diploid fungus that grows both as yeast and filamentous cell was chosen for this research. The theory of ion parametric resonance was taken as the base for studying the influence of electromagnetic field on biological structures. We tested the hypothesis, whether it is possible to observe the change in growth properties of Candida albicans with an AC electromagnetic field tuned to resonance with calcium ions cyclotron frequency. K e y w o r d s: biological structures, Candida albicans, low frequency electromagnetic field, exposure coil system, cyclotron resonance, ion parametric resonance

Lead Acid Battery Modeling for PV Applications

Abstract: Lead-Acid batteries continue to be the preferred choice for backup energy storage systems. However, the inherent variability in the manufacturing and component design processes affect the performance of the manufactured battery. Therefore, the developed Lead-Acid battery models are not very flexible to model this type of variability. In this paper, a new and flexible modeling of a Lead-Acid battery is presented. Using curve fitting techniques, the model parameters were derived as a function of the battery’s state of charge based on a modified Thevenin equivalent model. In addition, the charge and discharge characteristics of the derived model were investigated and validated using a real NP4-12 YUASA battery manufacturer's data sheet to match performance at different capacity rates. Furthermore, an artificial neural network based learning system with back-propagation technique was used for estimating the model parameters using MATLAB software. The proposed neural model had the ability to predict values and interpolate between the learning curves data at various characteristics without the need of training. Finally, a closed-form analytical model that connects between inputs and outputs for neural networks was presented. It was validated by comparing the target and output and resulted in excellent regression factors.

Application of digital filters to check quality of the automatically scaled ionograms

Abstract: The ionospheric observatory Pruhonice serves to monitor the state of ionosphere using ground-based vertical sounding instrument - the Digisonde DPS-4D. Measured ionograms are automatically evaluated (scaled) and basic characteristics are derived. The ionograms and the scaled parameters are sent to the international databases. Especially during disturbed conditions the automatic scaling could give unreliable results. This paper presents simple method how to detect accidental errors in automatic scaling based on the parameters derived from ionograms and on an application of the finite impulse response filters. K e y w o r d s: ionogram, F2 layer, critical frequency, virtual height, total electron content, finite impulse response filter The Digisonde DPS4-D installed at the observatory Pruhonice (50 ◦ N, 14.5 ◦ E) is used to monitor the ionosphere with the regular interval of 15 minutes [1]. Ionograms obtained by the Digisonde are automatically scaled using the special software ARTIST which is implemented in the Digisonde and this information is used to compute profile of electron concentration [2]. Automatic scaling is based on identification of characteristic shapes of the wave reflection and the results are sent to the international databases. The data are later used for local/global mapping and forecast of the main ionospheric parameters. At times, especially during geomagnetically disturbed conditions, various problems occur despite relatively high quality of the software (eg, secondary reflection or only parts of primary reflections are identified, or presence of the sporadic E layer shields upper laying layers etc.). Manual correction of the automatically scaled ionograms is time consuming and, in general, only small amount of ionospheric data can be checked by human. The aim of our work is to facilitate the control of the quality of the automatically scaled Digisonde data by means of a preliminary identification of possibly incorrectly scaled (miscaled) ionograms. This will lead to reduction of the total number of ionograms designed for the manual correction to only ionograms with increased probability of miscalling. The ionograms identified as incorrectly scaled are manually checked and, in case of need, corrected. An example of application of the proposed method of the preliminary ionogram scaling control based on the Total Electron Content (TEC) obtained from the GNSS and the Digisonde is described in the paper [3]. The method presented in this paper is based on the using of data from the Digisonde without fusion of sensors. In this case, digital filters can be used for automatically control process of miscalled ionograms. Digital filters are described in [4] and [5]. For our purposes, we use the MA (Moving Average) filters. Filters are applied on ionospheric parameters, namely total electron content (TEC), maximum plasma frequency (critical frequency f0F2) of the F2 layer, and virtual height of the F2 layer (hF2).

Modular Design Of Fast Leading Zeros Counting Circuit

Abstract: Abstract In modern computing technique, calculation of leading zeros in a data represented as strings of digits is used very often. Those techniques require high speed of the circuit, as well as its fast design. In this paper we propose a design of such a counter, which is applicable to data length of w = 4j bits, for 4 < j ≤ 8. With this solution it is also possible to process longer data, since the suggested technique offers a good modularity. This is very important, considering the current technology scaling trends. In this paper, a delay behavior of the proposed circuit has also been investigated using equations and VHDL simulation based worst-case delay estimation method. The results show a significant improvement of the circuit speed, compared to the known solutions.

Neural network and speed deviation based generator out-of-step prediction scheme

Abstract: A multi-layer perceptron neutral network (MLPNN) has been used as a decision tool to predict out-ofstep conditions. Rotor speed deviations are sampled and the maximum speed deviation in 1 cycle is obtained, and used as input to the MLPNN. Each generator has one trained MLPNN assigned to it to predict whether or not that generator will go out of step following a disturbance. The trained neural network responded to the 88 individual generator out-of-step (OOS) cases with 100% accuracy while the responses to 512 synchronism cases were 98.05% accurate. The 340 predictions for 34 simulations with all 10 generators in synchronism were 100% accurate. The study used the IEEE 39-bus as the test system.

An Efficient Functional Test Generation Method For Processors Using Genetic Algorithms

Abstract: Abstract The paper presents a new functional test generation method for processors testing based on genetic algorithms and evolutionary strategies. The tests are generated over an instruction set architecture and a processor description. Such functional tests belong to the software-oriented testing. Quality of the tests is evaluated by code coverage of the processor description using simulation. The presented test generation method uses VHDL models of processors and the professional simulator ModelSim. The rules, parameters and fitness functions were defined for various genetic algorithms used in automatic test generation. Functionality and effectiveness were evaluated using the RISC type processor DP32.

Modeling, Simulation, Hardware Implementation of a Novel Variable Pitch Control for H-Type Vertical Axis Wind Turbine

Abstract: Abstract It is well known that the fixed pitch vertical axis wind turbine (FP-VAWT) has some disadvantages such as the low start-up torque and inefficient output efficiency. In this paper, the variable pitch vertical axis wind turbine (VP-VAWT) is analyzed to improve the output characteristics of FP-VAWT by discussing the force of the six blade H type vertical axis wind turbine (VAWT) under the stationary and rotating conditions using built the H-type VAWT model. First, the force of single blade at variable pitch and fixed pitch is analyzed, respectively. Then, the resultant force of six blades at different pitch is gained. Finally, a variable pitch control method based on a six blade H type VP-VAWT is proposed, moreover, the technical analysis and simulation results validate that the variable pitch method can improve the start-up torque of VAWT, and increase the utilization efficiency of wind energy, and reduce the blade oscillation, as comparable with that of FP-VAWT.

McELIECE PKC CALCULATOR

Abstract: The original McEliece PKC proposal is interesting thanks to its resistance against all known attacks, even using quantumcryptanalysis, in an IND-CCA2 secure conversion. Here we present a generic implementation of the original McEliece PKCproposal, which provides test vectors (for all important intermediate results), and also in which a measurement tool for side-channel analysis is employed. To our best knowledge, this is the first such an implementation. This Calculator is valuablein implementation optimization, in further McEliece/Niederreiter like PKCs properties investigations, and also in teaching.Thanks to that, one can, for example, examine side-channel vulnerability of a certain implementation, or one can find out andtest particular parameters of the cryptosystem in order to make them appropriate for an efficient hardware implementation.This implementation is available [1] in executable binary format, and as a static C++ library, as well as in form of sourcecodes, for Linux and Windows operating systems.K e y w o r d s: post-quantum PKI, McEliece PKC, Niederreiter PKC, Patterson’s algebraic decoding algorithm, binaryirreducible Goppa codes, side-channel analysis

Thermographic analysis of a bridge power converter

Abstract: Any loss of power in converters is dissipated as heat in the components of the circuit. The article presents a new approach to measuring heat dissipation in a bridge power converter with hard switches using infrared thermography. Parallel measurements by thermocouples have been carried out. The experimental results are compared and used from the both cases. The proposed approach can be used for various circuit implementations of the converters in a similar manner. Powerful energy converters (inverters) are now widely used in renewable energy sources, induction heating, adjustable speed motor drives, uninterruptable power supplies and many others [1]. The simplest form of an inverter is the bridge-type and a very large number of inverters are ”hard-switched” voltage source inverters. Besides IGBTs, power MOSFETs are also used especially for lower voltages, power ratings, and applications that require a high efficiency and a high switching frequency. Research related to determination of heat losses in the electronic converters of electrical energy is closely connected to improving their energy performance and quality [2–4]. Most of the problems occurring at the end of the design cycle are associated with poor thermoregulation. Thermal management is crucial for the reliability of the system since 53% of failures are related to overheating [5]. As it is known, thermal qualification is particularly important for power semiconductors for two reasons [6]. Firstly, they work with high density currents with a steep temperature gradient between the junction and the environment. Secondly, their thermal mass is very small and the heat spreads for parts of a millisecond. Therefore, optimizing the efficiency or reducing the loss of the inverter is an important part of the design process and of the choice of components. One way to assess the losses in the inverter is by measuring the temperature difference of the components during the off state and steady state operation. Infrared Thermography (IRT) is a technique capable of revealing the presence of thermal anomalies in various objects. This technique begins to be used widely to monitor the temperature field of the power electrical components and systems. Recently, a number of articles have been published regarding the use of IRT for contactless thermal measurements to verify the results of thermal simulations of power electrical components and systems [7–9]. The article presents a new approach to evaluating the thermal losses in power converters using IRT. Experimental measurements are conducted using a laboratory setting of a bridge power converter with an AC output (inverter). Results are presented of evaluating the heat losses in the case of hard switching.

Influence Of Nanoparticles Diameter On Structural Properties Of Magnetic Fluid In Magnetic Field

Abstract: Abstract The properties of magnetic fluids depend on the nanoparticle diameter, their concentration and the carrier liquid. The structural changes in magnetic fluids with different nanoparticle diameter based on transformer oils TECHNOL and MOGUL under the effect of a magnetic field and temperature were studied by acoustic spectroscopy. At a linear and jump changes of the magnetic field at various temperatures a continuous change was observed of acoustic attenuation caused by aggregation of the magnetic nanoparticles to structures. From the anisotropy of acoustic attenuation and using the Taketomi theory the basic parameters of the structures are calculated and the impact of nanoparticle diameters on the size of structures is confirmed.

Use of Fuzzy Logic Systems for Assessment of Primary Faults

Abstract: In electric power systems, grid elements are often subjected to very complex and demanding disturbances or dangerous operating conditions. Determining initial fault or cause of those states is a difficult task. When fault occurs, often it's an imperative to disconnect affected grid element from the grid. This paper contains an overview of possibilities for using fuzzy logic in an assessment of primary faults in the transmission grid. The tool for this task is SCADA system, which is based on information of currents, voltages, events of protection devices and status of circuit breakers in the grid. The function model described with the membership function and fuzzy logic systems will be presented in the paper. For input data, diagnostics system uses information of protection devices tripping, states of circuit breakers and measurements of currents and voltages before and after faults.

Robust Gain–Scheduled PID Controller Design For Uncertain LPV Systems

Abstract: 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. © 2015 Slovenska Technicka Univerzita. All rights reserved.

A Coefficient Diagram Method Controller with Backstepping Methodology for Robotic Manipulators

Abstract: A new robust control procedure for robot manipulators is proposed in this paper. Coefficients diagram method controllers CDM and Backstepping methodology are combined to create the novel control law. Two steps of backstepping on the resulting system are used to design a nonlinear CDM-Backstepping controller. Simulations on a PUMA robot including external disturbances, parametric uncertainties and noises are performed to show the effectiveness and feasibility of the proposed method. K e y w o r d s: manipulators, backstepping approach, coefficients diagram method controller, robustness

Fuzzy Backstepping Torque Control Of Passive Torque Simulator With Algebraic Parameters Adaptation

Abstract: Abstract This work presents fuzzy backstepping control techniques applied to the load simulator for good tracking performance in presence of extra torque, and nonlinear friction effects. Assuming that the parameters of the system are uncertain and bounded, Algebraic parameters adaptation algorithm is used to adopt the unknown parameters. The effect of transient fuzzy estimation error on parameters adaptation algorithm is analyzed and the fuzzy estimation error is further compensated using saturation function based adaptive control law working in parallel with the actual system to improve the transient performance of closed loop system. The saturation function based adaptive control term is large in the transient time and settles to an optimal lower value in the steady state for which the closed loop system remains stable. The simulation results verify the validity of the proposed control method applied to the complex aerodynamics passive load simulator.

Multifunction current differencing cascaded transconductance amplifier (mcdcta) and its application to current-mode multiphase sinusoidal oscillator

Abstract: In this study, a new versatile active element, namely multifunction current differencing cascaded transconductance amplifier (MCDCTA), is proposed. This device which adopts a simple configuration enjoys the performances of low-voltage, low-input and high-output impedance, wide bandwidth etc. It simplifies the design of the current-mode analog signal processing circuit greatly, especially the design of high-order filter and oscillator circuits. Moreover, an example as a new current-mode multiphase sinusoidal oscillator (MSO) using MCDCTA is described in this paper. The proposed oscillator, which employs only one MCDCTA and minimum grounded passive elements, is easy to be realized. It can provide random n (n being odd or even) output current signals and these output currents are equally spaced in phase all at high output impedance terminals. Its oscillation condition and the oscillation frequency can be adjusted independently, linearly and electronically by controlling the bias currents of MCDCTA. The operation of the proposed oscillator has been testified through PSPICE simulation and experimental results. K e y w o r d s: current-mode circuit, multifunction current differencing cascaded transconductance amplifier (MCDCTA), multiphase sinusoidal oscillator (MSO), analog integrated circuit

Achieving an Equilibrium Position of Pendubot Via Swing-Up and Stabilizing Model Predictive Control

Abstract: In this paper, a complex control strategy to swing-up and balance the under-actuated pendubot system in one of its unstable equilibrium positions is presented. The initial swing-up maneuver is performed using an energy-based approach. For the purposes of stabilizing the system in its mid unstable equilibrium position a model predictive controller based on optimal control law with integral action is proposed. Satisfaction of constraints is ensured by introducing perturbations in the LQ control law acting as corrections when input amplitude/rate bounds are to be exceeded. The stability issue is addressed via additional constraints imposed on the terminal set. The emphasis of the paper is on the experimental realization of the pendubot swing-up followed by its balancing, which reveals the accuracy of the proposed control scheme. K e y w o r d s: pendubot, swing-up, stabilization, model predictive control, constrained optimization

Precise compact system for ionizing radiation detection and signal processing with advanced components integration and electronic control

Abstract: Quality and performance of a detection system are the crucial parameters in all nuclear physics experiments. This system serves as a source of all signals and noises to be processed. Better performance, higher amplification and lower noises occurrence simplify subsequent signal analysis. In the field of Mossbauer spectroscopy, the spectrum quality and Mossbauer effect are crucial parameters which are affected especially by the quality of the detection system. These parameters were evaluated for different types of a detection setup. Finally an improvement of the spectrum quality by 15% and Mossbauer effect by 7% has been achieved for the natural iron reference absorber measurement in comparison with previous version of the detection system. K e y w o r d s: gamma ray detection, signal processing, Mossbauer spectroscopy, Mossbauer spectrum