This article deals with the effect of selected machining parameter values in hard turning of tested OCHN3MFA steel in terms of SEM microstructural analysis of workpiece material, cutting forces, long-term tests, and SEM observations of flank wear VB and crater wear KT of used changeable coated cemented carbide cutting inserts in the processes of performed experiments. OCHN3MFA steel was selected as an experimental (workpiece) material. The selected experimental steel was analyzed prior to hard turning tests to check the initial microstructure of bulk material and subsurface microstructure after hard turning and chemical composition. Study of workpiece material’s microstructure and worn cemented carbide cutting inserts was performed with Tescan Vega TS 5135 scanning electron microscope (SEM) with the X-Ray microanalyzer Noran Six/300. The chemical composition of workpiece material was analyzed with Tasman Q4 surface analyzer. All hard turning experiments of the used specimens were performed under the selected machining parameters in the SU 50A machine tool with the 8th selected individual geometry of coated cementite carbide cutting inserts clamped in the appropriate DCLNR 2525M12-M type of cutting tool holder. During the hard turning technological process of the individual tested samples made of OCHN3MFA steel, cutting forces were measured with a Kistler 9257B piezoelectric dynamometer, with their subsequent evaluation using Dynoware software. After the long-term testing, other experiments and results were also realized, evaluating the influence of selected machining parameters with different cutting insert geometry on the achieved surface quality.

The above-threshold operation of a Fabry-Perot laser with a nonlinear PT (parity time) mirror is investigated. For the first time, the analysis accounts for gain saturation of an active medium as well as gain and loss saturation effects in the PT mirror. The obtained laser output intensity characteristics have been demonstrated as a function of various PT mirror parameters such as: the ratio of the PT structure period to laser operating wavelength, number of PT mirror primitive cells, and gain and loss saturation intensities of the PT mirror gain and loss layers. Two functional configurations of the laser have been considered: laser operating as a discrete device, and as a component of an integrated circuit. It has been shown that, in general, the laser operation depends on the PT mirror orientation with respect to the active medium of the laser. Moreover, when the laser radiation is outcoupled through the PT mirror to the free space, bistable operation is possible, when losses of the mirror’s loss layer saturate faster than gain of the gain layer. Furthermore, for a given saturation intensity of the mirror loss layers, the increase of the saturation intensity of the mirror gain layers causes increasing output intensity, i.e., the PT mirror additionally amplifies the laser output signal.

The article discusses the applicability of a novel method to determine horizontal curvature of the railway track axis based on results of mobile satellite measurements. The method is based on inclination angle changes of a moving chord in the Cartesian coordinate system. In the presented case, the variant referred to as the method of two virtual chords is applied. It consists in maneuvering with only one GNSS (Global Navigation Satellite System) receiver. The assumptions of the novel method are formulated, and an assessment of its application in the performed campaign of mobile satellite measurements is presented. The shape of the measured railway axis is shown in the national spatial reference system PL-2000, and the speed of the measuring trolley during measurement is calculated based on the recorded coordinates. It has been observed that over the test section, the curvature ordinates differ from the expected waveform, which can be caused by disturbances of the measuring trolley trajectory. However, this problem can easily be overcome by filtering the measured track axis ordinates to obtain the correct shape – this refers to all track segments: straight sections, circular arcs and transition curves. The virtual chord method can also constitute the basis for assessing the quality of the recorded satellite signal. The performed analysis has shown high accuracy of the measuring process.