Energy and Environmental Performance of Solar Thermal Collectors and PV Panel System in Renovated Historical Building

The major intent of this article was to determine the amount of energy received by two active systems used to convert solar radiation and to estimate their impact on reducing the emission of pollutants. Thermal solar collectors with an area of 51.36 m2 and photovoltaic panels with an area of 50.4 m2 were subject to comparative analysis. It was assumed that either of the two systems could be installed on the roof of an old tenement house located in Poznan (Poland), which is planned for renovation. Computer simulations made with DesignBuilder software were used as a research tool. Two main conclusions can be drawn from the analysis of the year-long operation of both systems in the conditions of a typical meteorological year. Thermal solar collectors can produce 469 kWh of heat from 1 m2 of the device annually, while PV panels can generate 136 kWh of electricity per year from 1 m2 of active area. However, it turned out that the use of photovoltaic systems can contribute to a higher reduction in pollutants emitted to the atmosphere as a result of the alternative combustion of fossil fuels. Additionally, the optimal angle of inclination of devices for solar radiation conversion located near Poznan was determined.

RENEWABLE ENERGY AND CLIMATE CHANGE IN SERBIA AND THE REPUBLIC OF SRPSKA

This paper focuses on the use of renewable energy sources in Serbia and the Republic of Srpska and their impact on the environment and climate change. Renewable energy sources used in Serbia are hydropower, solar energy, wind energy, biomass, and biogas. Renewable energy sources used in the Republic of Srpska are hydropower, solar energy, biomass, and biogas. When using hydropower, the formed reservoirs often impact the microclimate of the environment in which they are located. Photothermal and photovoltaic solar radiation conversion installations are mostly stationary, do not emit harmful substances into the environment, and have no impact on climate change. The use of wind turbines has a certain influence on the flow of ambient air. When using biomass and biogas, combustion gases are released into the atmosphere, which has slightly negative impact on climate change. The paper concludes that the use of renewable energy sources in Serbia and the Republic of Srpska has a negligible negative impact on the environment and climate change.

Quality of radiation conversion under four-wave mixing on thermal nonlinearity with feedback

Quality of radiation conversion under four-wave mixing on thermal nonlinearity with feedback for both signal and object waves has been investigated at high reflection coefficients. It has been shown that the optimal operating mode of a four-wave converter on thermal nonlinearity is the mode in which the pumping waves have equal intensities and there is a compensation for a phase shift arising from the pumping wave self-action. In this operating mode of the four-wave radiation converter, as compared with the case of the absence of feedback for both signal and object waves, a significant increase in the amplitude reflection coefficient is observed with an increase in the pumping waves intensities. In this case, despite the decrease in the bandwidth of spatial frequencies of the object wave with an increase in the pumping wave intensities, the quality of radiation conver-sion with feedback for both signal and object waves is better than in the absence of feedback.

Spectroscopic Studies of Laser-Based Far-Ultraviolet Plasma Light Source

A series of experiments is described which were conducted to measure the absolute spectral irradiances of laser plasmas created from metal targets over the wavelength region of 123–164 nm by two separate 1.0 μm lasers, i.e., using 100 Hz, 10 ns, 2–20 kHz, 60–100 ns full-width-at-half-maximum pulses. A maximum radiation conversion efficiency of ≈ 3%/2πsr is measured over a wavelength region from ≈ 125 to 160 nm. A developed collisional-radiative solver and radiation-hydrodynamics simulations in comparison to the spectra detected by the Seya–Namioka-type monochromator reveal the strong broadband experimental radiations which mainly originate from bound–bound transitions of low-ionized charges superimposed on a strong continuum from a dense plasma with an electron temperature of less than 10 eV.

Selective Couplers Based on Multiplexed Volume Holographic Gratings for Waveguide Displays

Diffraction waveguides are widely used in augmented reality devices as information display systems for the introduction of data into the human visual field in order to supplement information about the world around us. This paper formulates the principles of radiation conversion in diffraction waveguides made of photo-thermo-refractive glass on the basis of multiplexed volume holographic gratings, and the advantages and disadvantages of high spectral-angular selectivity are analyzed. In the optical scheme, each of the superimposed volume holographic gratings in the diffraction waveguide forms a corresponding part of the composite angular field of view of the augmented reality device. A proposed mathematical model based on angular multiplexing made it possible to synthesize the diffraction optical element for a new type of diffraction waveguide made from photo-thermo-refractive glass and to create a prototype with an angular resolution of at least 3.0 ± 0.5′, with a brightness change in the image of less than 20% and with a composite angular field of view of 32°.

Исследование концентраторных фотоэлектрических модулей с каскадными солнечными элементами

To study concentrator photovoltaic modules with GaInP/GaInAs/Ge triple-junction solar cells we used the measurement capabilities of a solar simulator accompanied by a computer simulation. The comparison of values of parameters for a module, Fresnel lens and triple-junction solar cell, obtained both experimentally and computed by means of the computer simulation, demonstrated good matching of results and high precision of calculations using the software. This allows to use both methods simultaneously to explain processes of radiation conversion in the system concentrator–solar cell and predict the values of module parameters under various external focusing conditions. The utilization of both methods revealed the impact of lateral currents on the total photo current of solar cells inside a module. For the system Fresnel lens–multi-junction solar cell we determined the possible cases of power loses associated with internal resistance of the cells. Output parameters of the module under varying spectrum of incoming radiation has been calculated using software.

Post radiotherapy, blue naevus conversion to basal cell carcinoma

<p class="abstract">Post-radiation conversion of benign cutaneous lesions to malignant is likely in the facial region. Thereby counselling and necessity of regular follow up is essential in patients undergoing radiotherapy in head and neck malignancies. Benign lesions undergo malignant change more so in the fascio cutaneous planes. A benign nasomaxillary blue naevus that transformed to malignant basal cell carcinoma following radiotherapy for pituitary adenoma is being reported.</p>