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Modern continuous lighting systems use powerful high-performance LEDs as light sources and an important task is to begin using alternative renewable energy sources for their power supply (including during the day). The simplest of the renewable energy sources is photovoltaic solar energy converter. However, solar photovoltaic generation depends significantly on many factors - geographical location, time of day, state of the atmosphere, time of year and the like. In addition, photovoltaic generation depends on the weather conditions and cloudiness, which makes it unstable and prone to change drastically (by an order of magnitude) during daylight hours. Therefore, an important element of the power system based on renewable energy sources is the system of accumulation of generated energy. The method of power stabilization using supercapacitors for systems with a significant change in power generation in the electrical power system is analyzed. The paper offers design principles of the power supply systems for powerful LEDs with supercapacitor energy storage devices intended to make the use of energy from sources with variable generation more efficient. The systems with supercapacitor-based drives, which allow to ensure stable operation of the lighting system when the power supply from an alternative source is absent or reduced, provide high safety and reliability, and have a significantly longer service life than battery-based energy storage systems.

Using LED technologies to create a comfortable light environment for human life and work can help reduce electricity consumption while maintaining, and usually improving, the energy and spectral parameters of lighting systems. At the same time, LED lighting systems for residential and industrial buildings are usually powered by electricity generated mainly by thermal power plants. Such plants mostly use fossil fuels and their combustion leads to environmental pollution. The article proposes the concept of a lighting system, which allows improving the ecology by reducing the energy consumption of lighting systems through the use of renewable energy sources. The proposed operation algorithm of the system for power supply control of LED light sources allows selecting the most appropriate energy sources in real time, thus making it possible to increase the luminous efficiency of the lamp by at least 20% when using industrial element base. This design can help to move away from traditional energy storage systems (batteries), which significantly increases the service life of such systems, their reliability and environmental safety. Placing photovoltaic converters in close proximity to the consumer (on the roofs and facades of buildings) ensures a decrease in ohmic losses and creates favorable conditions for using solar energy to light residential and industrial premises with LED lamps, which can significantly increase the economic and energy efficiency of such systems.

LED light sources, and powerful multichip light sources in particular, are currently widely used for lighting household and industrial premises. With an increase in power, the amount of heat increases as well, which leads to an increase in the temperature of semiconductor crystals and, accordingly, to a decrease in the reliability of LEDs and a change in their photometric characteristics. Therefore, when developing the design of LED lighting devices, special attention is paid to thermal management. Since the early 2000s, heat pipes have been widely used to efficiently remove heat from powerful electronic components. They do not require power for moving the working fluid and are most suitable for use in LED luminaires. In this study, the authors carry out a computer simulation of a cooling system based on heat pipes, which is then used to design and test a powerful compact LED lamp with a thermal load of up to 100 W. Heat pipes with a length of 150 mm are used to remove heat from the LED light source to the heat exchanger rings located concentrically around it. The heat exchanger rings are cooled by natural convection of the ambient air. The results of computer modeling of the temperature field of the developed cooling system show that at a power of the LED light source of 140.7 W, the temperature of the LED matrix case is 60.5В°C, and the experimentally measured temperature is 61.3В°C. The experimentally determined thermal power of the LED matrix is 91.5 W. The p-n junction temperature is 79.6В°C. The total thermal resistance of the cooling system is 0.453В°C/W. The obtained results indicate the effectiveness of the developed design.

The problem of climate change poses a challenge for humanity: it is necessary to reduce harmful emissions into the atmosphere, caused mainly by the burning of coal in thermal power plants. Partially, this problem can be solved by the use of energy-saving devices and equipment, including the replacement of traditional light sources with more efficient LEDs. This, however, causes the problem of ensuring normal thermal modes of the LEDs, since the more powerfull the LED is, the more heat is released in their semiconductor crystals, which leads to an increase in the temperature of the crystals and a decrease in the reliability of the device. This problem becomes especially urgent when using powerful multi-chip LED light sources, the so-called SOB matrices, whose power even now exceeds 500 W. This article presents a new design of a powerful LED lamp for indoor illumination of rooms with low ceilings. The heat from the LED is transferred via heat pipes to the heat exchanger rings looped around the light source. The heat exchanger rings are cooled by the natural convection of the surrounding air (at an ambient air temperature of 20°C). Computer simulation allowed evaluating the ability of the proposed cooling system to provide a normal thermal mode of the LED light source. The results on the computer simulations of the temperature field of light source's cooling system showed that when the LED power is 300 W, the temperature of the light source's base at the point where it is connected to the light source does not exceed 67.6°C. When the contact zone is covered with a 0.1 mm layer of heat-conducting paste (Arctic Silver 5 type) with a thermal conductivity coefficient of 8.7 W/(m·°C), the temperature of the LED case reaches 70°C. If the thermal resistance of the LED light source is 0.1°C/W, then the temperature of its semiconductor crystals will be 100°C, well below the allowable temperature value of 150°C. The total thermal resistance of the cooling system is 0.159°C/W.

The authors propose fundamentally new design-technological solutions for compact volumetric mirrorized LED modules with increased power. Test samples of volumetric light-effective LED light effective modules with a power of 10-15 W and light output of 105-160 lm/W for domestic retrofit lamps based on high-efficiency SMD, mini COB, and COB LEDs of third generation were ma­nu­fac­tu­red and tested. Positive technical and practical results were obtained by increasing by over 4-6 times the size of holders - heat sinks (compared to LED modules of flat holders) for heat dissipation from the LEDs by conduction and heat radiation, as well as by increasing light efficiency of LED lamps due to the additional light re-reflection by mirrorized reflectors-radiators in the bulb which is diffuser of the lamp light.

Given article presents the results of an experimental comparison of three radiators which are: pressed radiator made of aluminum plate (basic variant), radiator made of copper wire, and copper/water pulsating heat pipe. The radiators are intended to take off heat from the LED module with the power capacity of 10,55 W. It is established that under natural convection all three radiators can keep temperature level of the circuit board module less than 64 C that lies within the operating range. In comparison with basic variant the use of the copper wire radiator allows lowering of the temperature in the LED module center on 3.9 C, and the same value for the pulsating heat pipe is 7.1 C.

The energy spectrum of excited bound states of muonic molecules ptμ, pdμ, and dtμ is calculated on the basis of the stochastic variational method. The basis wave functions of the muonic molecule are taken in the Gaussian form. The matrix elements of the Hamiltonian are calculated analytically. For numerical calculation, a computer code was written in the MATLAB system. As a result, the numerical values of bound state energies for excited P-states of muonic molecules ptμ, pdμ and dtμ were obtained.

The given review allows to believe, that the decision of a complex technological, materialstechnological, technical problems at creation modern OLED- and PLED-devices in nearest 5—10 years will result in creation of devices with power efficiency more than 100 lm/W and service life till 100 000 hours. The realization of such parameters will allow to expand area of application of the considered systems and to create in the future unique flat powereffective organic lighting systems of new generation — light sources XXI of century.

Issues connected with research and development of reflective displays, based on electro-optical effects of bistability in cholesteric liquid crystals (LC) are considered. A number of methods for electronic control of matrix screens are offered using dynamic hysteresis as the main characteristic of high-resolution bistable cholesteric displays.The viewing angle characteristics of high-resolution cholesteric displays and advantages of the proposed class of LC devices in comparison with reflective displays based on different electrooptical effects in LC are shown. Further ways of improvement of bistable cholesteric displays with memory effect are also discussed.

We discuss current progress in laser cooling of lanthanides (Er, Yb, Dy, Tm etc.) focusing on applications. We describe some important peculiarities taking Thulium atom as an example: Two stage laser cooling, trapping in an optical lattice, anisotropic interactions and spectroscopy of narrow transitions. Specific level structure and presence of magic wavelengths make ultracold Thulium a favorable candidate for optical clock applications. On the other hand, abundance of Feshbach resonances allow to tune interactions in ultracold gases and thus reach quantum degeneracy. It opens intriguing perspectives for novel quantum simulators employing dipole-dipole interactions in an optical lattice.

The nitrogen-vacancy center in diamond attracts a lot of attention in sensing applications, mainly for temperature, magnetic field, and rotation measurements. Nuclear spins of carbon-13 surrounding the nitrogen-vacancy center can be used as a memory or sensing element. In the current work, a diamond plate with a relatively large concentration of carbon-13 was synthesized and examined. The spectrum of optically detected magnetic resonance was recorded and analyzed in a magnetic field range of 5–200 G. A strain-independent measurement technique of carbon-13 isotope concentration based on the analysis of magnetic resonance spectra was developed. Additionally, narrow features in the spectrum were detected and understood. [ABSTRACT FROM AUTHOR]