In geotechnology and mining, tools and equipment interact with aggressive geological material, causing the wear of these components. For this reason, it is important to determine the rate of abrasivity of individual geological materials, depending on the type of interaction with the tool. Various abrasivity tests have been developed in laboratories. Some of them are general, while others are special. What they all have in common is that they attempt to determine the abrasivity of rocks or soils in relation to the wear of the test specimens. This article gives an overview of the laboratory test methods for assessing the abrasivity of geological materials, which are useful in the field of geotechnology and mining engineering. General and special abrasivity tests are presented in detail. The aim of the article is to present existing laboratory tests to assess the abrasivity of rocks and soils, based on which further investigations of wear can be considered as part of a comprehensive approach to this tribological problem. Understanding of the wear mechanisms is the basis for the development of wear-resistant tools and models for predicting the tool life.
In Poland, the cadastre is the basic register which is the source of information on cadastral entities and their property. Therefore, it should constitute a reliable source of information in the scope of establishing the range of law, its nature, but also the subject of its ownership. However, it is necessary to be able to not only check the current information on the legal status and its scope, but also review past statuses or determine the rights that will influence real estate in the future. The cadastre and related rights are changing very dynamically over time, and each state has a very strict reference to the previous state. Therefore, in order to manage real estate in the most effective way, it is necessary to record temporal attributes of cadastre objects.
The main objective of this paper is to define the legal issues related to the possibility of registration at the time of creation or modification of object in the Polish cadastre. This paper includes analyses of both Polish legal regulations and European standards and norms. Moreover, the article presents the results of comparative analyses concerning the data model of cadastre and INSPIRE and Land Administration Domain Model (LADM) data models for the theme cadastral parcel in terms of temporal aspect.
The present article is dedicated to the study of the vibration properties of metal-based composite materials and the application of the non-destructive testing method. The main modal parameters of the metal-based composites were investigated. For experimental determination of natural frequencies and modes of oscillations, the method of scanning laser Doppler vibrometry was used. For the numerical modal analysis, the finite element method was used. The material model was a layered composite with isotropic linearly elastic layers and metal layers. The task of identifying the material model was considered as the problem of minimising the discrepancy between the calculated natural frequencies and the experimental ones. The developed method can be recommended for the determination of parameters of material models for calculating the modal characteristics of polymer–metal sandwich sheets and metallic mono-materials composite products. Methodology for identifying models of elastic behaviour of polymer–metal composite materials, based on the results of the experimental modal analysis, is presented. Wavelet-based damage detection is also presented as an appropriate approach for the identification of integral conditions of the metal–polymer–metal composite materials. Results of wavelet transform convolutions are presented.
The paper presents dynamical models of controlling voltage and frequency of ship’s electric supply set. The simulation model of synchronous generator, implemented in Matlab/Simulink, was described. For the developed simulation model, developed control systems using fuzzy controllers type P and PD were presented. Simulation research for resistance, inductive and capacitive loads were carried out for these regulators. Sample results of simulation tests are presented in the form of voltage waveforms at the output of the generator and rotational speed of the internal combustion engine for various load conditions. The conducted tests allow to assess the quality of the control process using fuzzy controllers and thus ensure the selection of the optimal solution.
The article presents modeling research on the M/S “Ziemia Zamojska” reduced model, carried out in an open fresh water area by a team of employees of the Department of Operating of Floating Vessels, Polish Naval Academy, Gdynia. The research involved circulating the model with constant angle of heel on the selected side, and the main engine set to full speed ahead. Using a real ship to carry this type of investigations is risky. It may lead to some failures like e.g. rudder failure, steering gear malfunction, overload and in some circumstances even main engine seizure. For this reason, ships are not tested with the rudder put to starboard or to port at the full speed ahead setting, even during a “Crash Stop” maneuver. However, based on the analysis of accidents at sea, and practical experience, it appears that during real operating conditions of vessels, there may occur situations when, for the sake of safety, the maneuver mentioned above must be carried out. Therefore, the authors had to conduct model tests of a floating vessel for the described case of ship operation
The paper presents results of research based on analysis of historical and present studies of the Arctic ice drift. Current information about Arctic ice drift comes from the scientific expedition organized by the Alfred-Wrgener-Institut Helmholtz Centre for Polar and Marine Research (AWI) from Bremerhaven (Germany) in the Arctic Ocean, as a part of the Multidiscipli-nary drifting Observatory for the Study of Arctic Climate (MOSAiC), coming from the deck of the icebreaker RV “Polarstern”. The main purpose of the article was to collect and illustrate information on the phenomenon of ice drift in the Arctic Ocean, considering data from ongoing research during the MOSAiC expedition. The average movement speed of the icebreaker RV “Polarstern” frozen in Arctic ice during the first three legs of the expedition was over 5 Nm/day, which is characteristic of the current data relating to the speed of the Arctic ice drift in the place of research. On the other hand, the article is popular science, and presents the overall characteristics of Arctic ice drift with an indication of the general directions, and speed of its movement. Ice drift speeds in the Arctic can reach exceptionally high values under favorable conditions. The drift of sea ice reaching at its intensity/intensity values close to the limit (dangerous criterion) in these extreme cases is called the “ice river”. The speed of “ice rivers” can reach up to 1–2 knots, however, in extreme conditions up to 9 knots. Based on data from the AWI, correlation points were identified between the speed of Arctic ice drift and the speed of winds and atmospheric pressure values.
The stochastic processes theory provides concepts, and theorems, which allow to build the probabilistic models concerning accidents. “Counting process” can be applied for modelling the number of road, sea, and railway accidents in the given time intervals. A crucial role in construction of the models plays a Poisson process and its generalizations. The nonhomogeneous Poisson process, and the corresponding nonhomogeneous compound Poisson process are applied for modelling the road accidents number, and number of people injured and killed in Polish roads. To estimate model parameters were used data coming from the annual reports of the Polish police.
A 2×2 MIMO wireless communication system with channel estimation is simulated, in which two transmit, and two receive antennas are employed. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting. Data are modulated by coherent binary phase-shift keying, whereupon an orthogonal space-time block coding subsystem encodes information symbols by using the Alamouti code. Based on the simulation, it is ascertained a possibility to decrease the bit-error rate by substituting the Hadamard sequences for the sequences having irregular structures, and constituting the eight known orthogonal bases. Considering a de-orthogonalization caused by two any pilot sequence symbol errors, the bit-error rate is decreased by almost 2.9 %. If de-orthogonalizations are caused by two repeated indefinite, and definite pilot sequence symbol errors, the decrements are almost 16 % and 10 %, respectively. Whichever sequences are used for piloting, the 2×2 MIMO system is ascertained to be resistant to the de-orthogonalization if the frame is of 128 to 256 symbols piloted with 32 to 64 symbols, respectively.
During 1984–1997, the ferronickel plant in Drenas used iron-nickel ore from the mines of the Republic of Kosovo: Glavica and Çikatove (Dushkaje and Suke) mines. However, during the years 2007–2017, when the plant started operating from the cessation of production, which was from 1998 to 2007, some types of iron-nickel ores from different countries began to be used, starting from iron-nickel ores from Kosovo, iron-nickel ores from Albania, ores from Indonesia, ores from the Philippines, ores from Guatemala, ores from Turkey and ores from Macedonia. The ore composition, however, is mainly oxide-laterite ore. Iron-nickel ores in the plant are characterised by high moisture content, a very important factor influencing the process of scraping the charge in rotary kilns and presenting in general. Among the iron-nickel ore used in the ferronickel plant, the ores from Albania are characterised due to their low moisture content when compared with the other ores as well as the high content of iron oxides, which affect the temperature rise inside the furnaces, as the iron ores play an important role in the pre-casting process in rotary kilns.