Volume 72 (2021): Issue 2 (April 2021)

This paper discusses the automatic generation of controller codes through a model created in the MATLAB environment the aim of the research is to simplify the implementation and tuning of the closedloop circuit in industrial systems in this context, the concepts and steps outlined herein could produce a more intuitive and powerful alternative to the pre-defined software components of control systems that enable closed-loop control. We propose a methodology for identifying the system through an industrial control setup, creating a control loop model, and generating a code implementable in the control setup. Importantly, we also present and compare the results obtained with various variants of the automatically generated control circuit containing a pre-defined controller of the industrial control system. The outcomes of the research allow us to conclude that the implementations generated by the model perform better that the option using a built-in controller.

Current vehicles are increasingly dependent on Electronic Control Units (ECUs) that control virtually every system of the vehicle. To enable advanced features automotive embedded systems are opening to external world, which raises security concerns. At the same time these innovative systems require more complex software and higher bandwidth for information exchange. Thanks to its bandwidth, payload size, and openness, Ethernet is a candidate technology for future in-vehicle architectures. This paper deals with design of a novel approach to secure In-vehicle Systems by taking advantage of Ethernet/IP technology and proven security mechanisms from TCP/IP model. Main goal is to design an efficient solution that meets requirements for latency without requiring high amounts of processing power and provides secure exchange of control messages. The work is mainly focused on the widespread Controller Area Network (CAN). The presented solution is based on encapsulation of CAN frames into UDP datagrams with added authenticity, integrity, and (if required) confidentiality of communication using IPsec protocol in transport mode. This creates a “secure tunnel across backbone Ethernet network in a vehicle. Next part of the paper presents extensive tests in simulation that are based on our previous experiments on hardware, in order to evaluate the characteristics of the designed security extension. The results indicate that using IPsec is a viable solution for securing in-vehicle communications.

In this study, we propose a geometric feature set for 2D shape retrieval. Conventional Hough feature gives the edge locations along with angle and creates Hough table if there are multiple intersections at borders. In this paper, a statistical way to represent the relation of repeating contours at each angle around the shape centroid is presented. The main contribution of this paper is to use the standard deviation of repeating contours. We calculate the angle between the shape centroid and each point on the contour. For each integer angle value, three features were extracted: the number of contour repetitions, the average distance of the points at that angle to the centroid, and the standard deviation of the points at the same angle. Thus, a 2D image was represented by a constant sized matrix, regardless of its size. In the case of similarity between two images, instead of merging features within a single expression, the algorithm picked the feature with the highest similarity rate for that comparison. We tested the proposed method on MPEG-7, Kimia99, ETH-80 datasets for a benchmark with the state-of-the-art. It outperformed most of the recent methods in terms of retrieval rate.

In this work we have analysed the basalt rocks from the area of Mount Etna using ⁵⁷Fe Mössbauer spectroscopy (MS), X-ray diffraction (XRD) and X-ray fluorescence analysis (XRF). Mössbauer spectroscopy was used to identify and to quantify the content and the magnetic nature of the iron-bearing minerals in the lava samples. Magnetite, olivine, pyroxene, hornblende, hematite and goethite of different relative abundances were found in the investigated samples. X-ray diffraction supported the structural analysis and determined the phases not visible by MS, like albite and calcite. X-ray fluorescence was employed to provide compositional analysis of the studied samples. The used methods showed qualitatively similar composition of the investigated rock samples, even though they also disclosed the quantitative differences in phase proportions agreeing with observed sample coloration. Identified compositional variations may result from the different processes during basalt formation and/or unequal weathering history.

This paper deals with the development and experimental verification of a low-power AC/DC converter. The proposed solution is aimed at the sub 0.5 W output power domain, commonly encountered in applications such as always-on wireless sensing nodes. To implement the proposed converter topology, a prototype application specific integrated circuit was designed and manufactured in a high voltage 0.35 µm CMOS technology, able to handle the maximum voltage of up to 120 V. The proposed design was first analyzed by transistor-level simulations showing high power efficiency and low no-load consumption of the developed converter. To facilitate experimental verification and measurement, an printed circuit board with the necessary external components was developed, as the available technology is unable to handle the AC line voltage directly. While the developed converter operated well with decreased input AC voltage, reliability issues arose during operation with the full AC line voltage of 230 Vrms. These are linked to digital control circuitry of the implemented chip and could be addressed in the second manufacturing run in the future.

This paper introduces a generalized PID type controller for controlling high-order dynamical systems. An optimal generalized PID control design method is developed to provide a simplified high-order output feedback control design procedure and tunable response characteristics. The controller design procedure is reduced to the specification of the desired natural frequency and the solution of a polynomial equation. The control method is capable of providing a desired control performance under set-point and disturbance variations. The performance of the proposed control method is implemented on some unstable and nonlinear mechatronic systems to illustrate the robustness, e ectiveness and feasibility of the method.

In this paper we consider the network of mobile users where CDMA technique is used in cells. The dependence of disturbances/interference in the uplink direction as a result of surface user distribution in the neighbouring cells is determined. Three user distribution types are considered: the uniform one, decreasing from the cell centre to the rim and the increasing one. The interference calculation is performed using mean values of user distance from the cell centre. It is proved in the paper that interference caused by decreasingly and increasingly distributed users may differ from the interference caused by the cell with uniform user distribution by not more than ±75%.

Generally, the longitudinal magnetic field of the transverse electric (TE) wave inside a waveguide is obtained by solving the corresponding Helmholtz wave equation, which further leads to the derivation of the remaining fields. In this paper, we provide an alternative way to obtain this longitudinal magnetic field by making use of one of the Maxwell’s equations instead of directly relying on the Helmholtz wave equation. The longitudinal electric field of the transverse magnetic (TM) wave inside a waveguide can also be derived in a similar fashion. These derivations, which are different from those found in the introductory textbooks on microwave engineering, make the study of waveguides more interesting.

This mini review covers a brief overview of three generations of solar cells, definition of major photovoltaic (PV) parameters, mechanisms, advantages and limitations of different types of solar cells such as multijunction, thin film, quantum dot, dye sensitized and perovskite solar cells, and what role the earth abundant selenium can play in each type of solar cells, followed by a comparative study of the benefits and challenges that selenium can offer in terms of PV properties, as well as the major players and cost analysis in this arena. As far as PV properties are concerned, BaZr(S_0.6Se_0.4)₃ distorted chalcogenide perovskite solar cell can possibly lead the future, the next best ones being AlGaInP multijunction solar cell with Se emitter dopant and Se electrolyte additive in Zn-Cu-In-Se QD-sensitized solar cell. Cost-wise perovskite cell holds a lot of promise, but the efficacy of selenium needs to be explored further.

The article analyzes electricity prices in Slovakia, their distribution tari component, and their significant impact on small-scale photovoltaic power plants (PVPs). Fixed part of the distribution tari component in Slovakia varies considerably, given the region of operation of the distribution system operator as well as the allocated tari rate. Profitability of the small-scale PVP in Slovakia is widely discussed, with differing opinions of the lay and professional public. The article will explain under what circumstances all the opinions may be true. Profitability predictions available online or done by PVP installers are extremely simplified and lead to misleading results. The existence of fixed and variable components of the price plays a significant role and a simple change of the electricity tari may bring significant savings and shorten the payback time of the PVP investment. However, this is a complex issue and requires several other factors to be considered, too. The most important ones are the fixed component of the electricity price, household consumption diagram and the distribution system to which the household is connected.