The field of indoor lighting covers a wide range of lighting uses with varying requirements for lighting conditions to be satisfied by properly selected lighting equipment. The need to frequently change the arrangement of useable areas entails the necessity to adapt the lighting to new requirements. A good solution for reducing costs and saving time is a luminaire adjusting the luminous flux and spatial luminous intensity distribution in a wide range. The authors present the concept of an adaptive luminaire and its construction assumptions. In addition, the results of studies on the development of the concept are shown together with conditions and limitations that influenced the construction of the luminaire. The analysis of the surface of the moveable reflector is presented, and the results of testing the luminaire prototype are compared with the results of simulation tests.

This paper focuses on the matter of cogging torque reduction by combining various methods of cogging torque minimization. Due to the high costs of prototype construction, cogging torque is minimized during the design phase by using numerical methods, while computer simulations are used to find a magnetic circuit arrangement for which the cogging torque has the smallest possible value. Cogging torque occurs as a result of combined impact of the magnetic field of a permanent magnet located at rotor and stator with variable magnetic conductivity depending on an angle of rotation. It is a pulsating torque and occurs permanently during machine operation, impacting the operation of the entire device cooperating with the electric machine and causing vibrations, tension, and noise. It results in braking torque and subsequent power losses and leads to faster wear and tear of machine structural elements. High cogging torque values cause problems with rotational speed adjustment. In the case of electric generators used in wind power plants, it impedes the start-up of power plants at high wind speeds. Considering the above, the reduction of cogging torque in permanent-magnet machines is extremely important.

Solid-state light sources are currently the fastest-growing group of light sources, replacing the previously used discharge and incandescent light sources. Thermal operating conditions of LEDs (Light Emitting Diode) play an important role in t maintaining long service life and constancy of luminous-electrical parameters. In the field of illumination, the service life parameter of light sources is important for the costs of maintenance of the illumination system, while the maintenance of the value of certain light parameters over time, such as luminous flux, color temperature and color rendering index, is related to the aesthetic effect of the illumination. In addition, limiting the junction temperature of solid-state light sources is particularly important in high-power luminaires dedicated to flood illumination. One of the elements shaping the thermal operating conditions of multi-source LED luminaires is the number of luminaires used, their arrangement, and the distance between LEDs installed on the MCPCB (Metal Core Printed Circuit Board) substrate. This article presents the results of simulation studies, realized using CFD (Computational Fluid Dynamics) software, where the temperature distribution and the junction temperature of the LED panel were determined for different configurations and distances between the LEDs. The results obtained were analyzed and conclusions were drawn based on them. Thermal tests performed and presented in the article cover scientific issues related to shaping the temperature distribution of the LED panel. They make it possible to determine the influence of thermal couplings between the sources, related to their number, distance and the value of the forward current, on the final temperature of the LED junction temperature. The presented research results may constitute auxiliary materials for designers of lighting luminaires, especially high-power luminaires, where a large number of high-power LED sources are installed in close proximity.

The article presents selected results of research on improving pedestrian traffic safety. Based on annually-updated accident statistics made available by the police, as well as the new pedestrian traffic regulations in force, detailed work was undertaken to assess the level of visibility of pedestrians by drivers in pedestrian crossing areas. The research was carried out by analyzing several characteristic cases of pedestrian crossings occurring in Poland, in which there was only dedicated lighting for crossings, only street lighting, and a variant of coexistence of both of the above lighting solutions. Illuminance measurements were made in the horizontal and vertical planes of pedestrian crossings, and the results were confronted with the relevant guidelines. The next step involved a complementary measurement of the luminance distribution of the vertical plane containing the pedestrian and a portion of the sub- and super-horizontal background. Visibility pedestrians was considered in positive and negative contrast variants, and was then related to the obtained results of the illumination distribution. The analysis of the results of the study indicated the possibility of limited visibility of pedestrians at the crossings despite the satisfactory results obtained from measurements of the illuminance distribution within the crossings.

The article presents the results of Rth_j-c thermal resistance research for selected high power semiconductor light source. The thermal resistance between the junction and the casing of semiconductor light sources is one of the key parameters determining the correct junction temperature of the LED sources and its influence on the basic light and electric parameters of semiconductor light sources. The research were carried out in accordance with the international standard JEDEC JESD51-14 using the Mentor Graphics measuring equipment.

The article presents the results of research on a reflector used in a luminaire with a variable luminous intensity distribution, which is a key element shaping the distribution of the luminous flux in space. The aim of the research is to analyze the impact of the reflective properties of the materials used for the production of reflectors on the possibility of obtaining appropriate luminous flux distribution characteristics and to assess the possibility of using specific materials in a system with variable luminous flux distribution