In Polish mining enterprises, mining exploitation processes are often carried out in much more difficult geological and mining conditions. At the same time, underground operation must be carried out in accordance with the legal requirements concerning work safety and public safety. In these circumstances, taking into account the fact that hard coal mining is by nature a less competitive industry, it should be stated that in Poland managing a mining enterprise is a real challenge. Additionally, in the situation of the functioning of mining enterprises in the conditions of the market economy and constant changes in the economic situation for coal, both on the domestic and foreign markets, the degree of management difficulties, including planning and decision making, is constantly increasing. This is a result of not only the specificity of mining production processes, but also the need to conduct effective economic activity in a constantly and dynamically changing environment. During the implementation of changes in a mining enterprise, the variety of conditions often increases difficulties in the change forecasting system and generates a high risk of implementing adaptive measures. The changes may have a different scope – from gradual, aimed at improving the activities carried out or slowly adapting to changes in the environment, through changes in implemented processes, to radical changes in functioning, often associated with organizational changes.This article aims to present the method of managing a mining enterprise, Poland Grupa Górnicza SA, established during the period of significant changes that took place at that time, both in the company itself and in the hard coal mining industry.

In recent years, the Steer-by-Wire (SBW) technology has been gaining popularity and replacing classical steering systems. It plays the most crucial role in autonomous cars where the vehicle must perform maneuvers on its own without driver’s intervention. One of the key components of this system is the steering wheel angle sensor (SAS). Its reliability and performance may affect driver’s life and health. The purpose of this paper is to show a test system to comprehensively evaluate the performance of the steering wheel angle sensor in the SBW system during real-world maneuvers and show how SAS parameters such as accuracy of angle, angular speed etc. affect car trajectory resulting in hit cones.
For this purpose, a test system was built, with the use of virtual test drives based on CarMaker software, CANoe and VTSystem hardware. In order to evaluate its performance, the errors introduced by the system were determined. Additionally, using the realised test system, three commercial steering wheel angle sensors were tested and compared during a virtual test drive. Their errors were determined, as well as their performance in the SBW technology and the consistency of the obtained results with the parameters declared by the manufacturer were verified as well.

Noise control is essential in an enclosed machine room where the noise level has to comply with the occupational safety and health act. In order to overcome a pure tone noise with a high peak value that is harmful to human hearing, a traditional reactive muffler has been used. However, the traditional method for designing a reactive muffler has proven to be time-consuming and insufficient. In order to efficiently reduce the peak noise level, interest in shape optimization of a Helmholtz muffler is coming to the forefront.

Helmholtz mufflers that deal with a pure tone have been adequately researched. However, the shape optimization of multi-chamber Helmholtz mufflers that deal with a broadband noise hybridized with multiple tones within a constrained space has been mostly ignored. Therefore, this study analyzes the sound transmission loss (STL) and the best optimized design for a hybrid Helmholtz muffler under a space- constrained situation. On the basis of the plane wave theory, the four-pole system matrix used to evaluate the acoustic performance of a multi-tone hybrid Helmholtz muffler is presented. Two numerical cases for eliminating one/two tone noises emitted from a machine room using six kinds of mufflers (muffler A~F) is also introduced. To find the best acoustical performance of a space-constrained muffler, a numerical assessment using a simulated annealing (SA) method is adopted. Before the SA operation can be carried out, the accuracy of the mathematical model has been checked using the experimental data. Eliminating a broadband noise hybridized with a pure tone (130 Hz) in Case I reveals that muffler C composed of a one- chamber Helmholtz Resonator and a one-chamber dissipative element has a noise reduction of 54.9 (dB). Moreover, as indicated in Case II, muffler F, a two-chamber Helmholtz Resonator and a one-chamber dissipative element, has a noise reduction of 69.7 (dB). Obviously, the peak values of the pure tones in Case I and Case II are efficiently reduced after the muffler is added.

Consequently, a successful approach in eliminating a broadband noise hybridized with multiple tones using optimally shaped hybrid Helmholtz mufflers and a simulated annealing method within a constrained space is demonstrated.

Cet article propose de considérer le processus de construction d’une idée grammaticale en se penchant sur la distinction généralement opérée entre les deux opérateurs du futur en arabe, sa- et sawfa dans le sens futur proche vs. futur lointain. Si, comme cet article le rappelle, cette distinction est linguistiquement contestée, il montre qu’elle est aussi contestable d’un point de vue grammatical, et ce même si un grand nombre de grammairiens arabes médiévaux de haute stature la relaient. Cet article se propose donc d’en retracer l’origine probable et, incidemment, revient sur l’édition du Kitāb de Sībawayhi faite par Hartwig Derenbourg qui aurait pu être perçue, en le cas d’espèce, comme l’une des origines probables de cette distinction. L’article propose alors de replacer celle-ci dans son contexte intellectuel: une affinité élective faisant se rejoindre des principes grammaticaux et ceux du courant rationaliste du muʿtazilisme ainsi que l’irruption de la logique grecque dans les études arabes seraient au berceau de cette antienne grammaticale.