The measurement of frequency characteristics, like magnitude and phase, related to a specific transfer function of DC–DC converters, can be a difficult task – especially when the measured signal approaches the boundary of a small-signal model validity (i:e. 1/3 of the switching frequency fS). It is hard to find a paper where authors mention the measurement techniques they use to draw frequency characteristics. Meanwhile the presence of noise in the output signal does not enable to directly measure the gain and the phase shift between the input and output signals. In such situations additional analysis is required in order to achieve a reliable result. This paper contains a description of a few methods that can be used to analyse measured signals in order to determine the gain and the phase shift of a specific transfer function. They enable to verify mathematical models in a wide range of frequencies (up to 1/3 fS). The methods use signals measured in the time domain and can be implemented in mathematical software such as Matlab or Scilab.

The article proposes the method of synthesis of active elements with time-varying parameters R(t), C(t) and L(t). In order to construct the elements, it is necessary to use operational amplifiers, multipliers and classic RLC components. The variability in time of the elements results from applying voltage to control terminals. Assuming that the parameters of elements R(t), L(t), C(t) are exponentially varying, dependencies describing the control voltage waveforms which enable such a parameter variability were determined. The obtained results were illustrated with examples and PSpice simulations.

The historic municipal park located in Zduńska Wola is covered in the central and northern part by conservator protection through an entry in the register of monuments and on the basis of an entry in the local spatial development plan. In terms of nature, the area has significant values due to old trees and the water system, which consists of two ponds fed by the Pichna River. As part of the preparatory work for the revalorization of the park, several studies and analyses were carried out, including assessment of the sanitary state of waters of Pichna River that supplies reservoirs. Degree of the river pollution made it impossible to restore the water system, the most important element of the park, while further supplying the ponds with river water. In order to ensure a satisfactory degree of purity and transparency of water in ponds, a decision was made to apply complex and modern technological solutions enabling the renovation of the water system. Project documentation was developed in 2015. After two years, they began to implement the project. Banks of both ponds were formed more gently, and the basins were deepened. Selection of vegetation around the reservoir and in the reservoir itself was based on the principle of biocenotic assumptions. The designed system is equipped with a circulation pump, skimmers, bottom drains, mechanical-mineral filter, swamp filter. This was to ensure adequate purification of water in ponds, based on natural processes, stimulated by the use of new, pro-ecological technologies.

The author, putting the metaphor of “a living dead” to the interpretation, tries to find the common points in the creative output of both writers i.e. Pushkin and Kharms. Both writers, belonging to extremely different literary periods and using other medium, were interested in the most important matters, among others the matter of life and death. Paradoxical metaphor of “a living dead” may imply not only a person being physically exhausted but above all a person deprived of emotions, experience and human reactions, whose fate brings nothing else but the inevitability of death. However, the matter that links both Pushkin and Kharms is the concept of “a coincidence”, which rules human fate, which is unpredictable, hard to avoid and which is a tool at hands of the providence.

In cyclic articles previously published we described and analysed self-organized light fibres inside a liquid crystalline (LC) cell contained photosensitive polymer (PP) layer. Such asymmetric LC cell we call a hybrid LC cell. Light fibre arises along a laser beam path directed in plane of an LC cell. It means that a laser beam is parallel to photosensitive layer. We observed the asymmetric LC cell response on an external driving field polarization. Observation has been done for an AC field first. It is the reason we decided to carry out a detailed research for a DC driving field to obtain an LC cell response step by step. The properly prepared LC cell has been built with an isolating layer and garbage ions deletion. We proved by means of a physical model, as well as a numerical simulation that LC asymmetric response strongly depends on junction barriers between PP and LC layers. New parametric model for a junction barrier on PP/LC boundary has been proposed. Such model is very useful because of lack of proper conductivity and charge carriers of band structure data on LC material.