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Background/Aim. In the past two decades, we have witnessed the emergence of new radiation therapy techniques, radiotherapy treatment planning system (TPS) with calculating algorithms for the dosage calculation in a patient, units for multislice computed tomography (CT) and image-guided treatment delivery. The aim of the study was investigating the significant difference in dosimetric calculation of radiotherapy TPS in relation to the values obtained by measuring on the linear accelerator (LINAC), and the accuracy of dosimetric calculation between calculating algorithms Analytical Anisotropic Algorithm (AAA) and Acuros XB in various tissues and photon beam energies. Methods. For End-to-End test we used the hetero-geneous phantom CIRS Thorax002LFC, which anatomically represents human torso with a set of inserts known as relative electron densities (RED) for obtaining a CT calibration curve, comparable to the “reference” CIRS 062M phantom. For the AAA and Acuros XB algorithms and for 6 MV and 16 MV photon beams in the TPS Varian Eclipse 13.6, four 3D conformal (3DCRT), and one intensity modulated (IMRT) and volumetric modulated arc (VMAT) radiotherapy plans were made. Measurements of the absolute dose in Thorax phantom, by PTW-Semiflex ionization chamber, were carried out on three Varian-DHX LINACs. Results. The difference between “reference” and measured CT conversion curves in the bone area was 3%. For 476 phantom measurements, the difference between measured and TPS calculated dose of 3–6%, was found in 30 (6.3%) cases. According to regression analysis, the standardized Beta coefficient for relative errors, 6 MV vs. 16 MV, was 0.337 (33.7%, p < 0.001). Mean relative errors for AAA and Acuros XB, using Mann-Whitney test, for bones were 1.56% and 2.64%, respectively (p = 0.004). Conclusion. End-to-End test on Thorax002LFC phantom proved the accuracy of TPS dose calculation in relation to the one delivered to a patient by LINAC. There was a significant difference for photon energies relative errors (higher values are obtained for 16 MV vs. 6 MV). A statistically significant minor relative error in AAA vs. Acuros XB was found for the bone.

With the significant increase in the amount of solar energy sources, the variation in the production caused by the stochastic nature of these sources becomes a larger problem for the electrical grid. Having a large percentage of installed units, therefore, requires some type of both short- and long-term planning of energy production. Most planning and forecasting tools require a large amount of solar energy data for the location in question and oftentimes that data is difficult to obtain. In this paper, we propose a method for generating synthetic solar irradiance data and test its applicability on forecasting and long-term planning problems. Synthetic data are generated using various generative adversarial networks and masked autoencoder based models, which are all trained on a dataset of solar irradiance data measured on the territory of the city of Banja Luka in Bosnia and Herzegovina. The synthetic data are evaluated both on different types of short-term forecasting tools and a long-term solar plant simulation tool, and the obtained results are compared with the cases where real data is used. By comparing the results, we have concluded that by using generative models we are able to generate synthetic data which is not only realistic, but applicable for both of these uses. [ABSTRACT FROM AUTHOR]

Polymer composite films of tris‐(8‐hydroxy‐quinoline) aluminum (Alq3) and polymethyl methacrylate (PMMA) at two different concentrations were investigated. Dielectric properties of the samples were measured in broad frequency range and results show an increase in specific conductance and susceptance by adding Alq3 in PMMA. Changes in dielectric spectra caused by irradiation of the samples with LED lamps at different wavelengths were also recorded. The samples were examined by UV–Vis and Fourier transform infrared spectroscopy. The interaction between Alq3 and the polymer matrix was observed in the photoluminescence spectroscopy spectra. The doping of the PMMA with different concentrations of the Alq3 leads to the unique photodielectric properties of the resulting composite, and that is the main result of this study. Due to its interesting optical and photodielectric properties, PMMA/Alq3 film may find application in solar cells and optoelectronics. [ABSTRACT FROM AUTHOR]

Introduction: Using computed tomography (CT) and treatment planning systems (TPS) in radiotherapy, due to the difference in photon beam energy on CT and linear accelerator, it is necessary to convert Hounsfield units (HU) to relative electron density (RED) values. The aim of this dosimetric study was to determine whether there is a significant effect of potential in the CT tube, field of view size (FOV), and phantom dimensions on the CT conversion curve CT-RED. The second aim is whether there are significant differences between the CT-RED obtained by the Computerized Imaging Reference Systems (CIRS) Thorax 002LFC phantom and the "reference" curve in the TPS, obtained by the CIRS 062M pelvis phantom, at the same CT conditions. Methods: Heterogeneous CIRS 062M and CIRS Thorax 002LFC phantoms were used, which anatomically and dimensionally represent the human pelvis, head, and thorax, with a set of known RED inserts. They were scanned on a CT LightSpeed GE simulator and obtained CT-RED. Results: The high voltage in the CT tube had a significant effect on the HU (t = 10.72, p < 0.001) for RED values >1.1, while FOV as a parameter did not show statistical significance for the 062M pelvis phantom. Comparing the slopes (062M pelvis and head) of the CT-RED for RED ≥ 1.1, the obtained value is t = 1.404 (p = 0.163). In the case of a 062M pelvis and a 002LFC phantom, we have seen a difference in RED values (for the same HU value) of 5 % in the RED region ≥ 1.1 (bone). Conclusion: Patients should be imaged on a CT simulator only at the potential of the CT tube on which the conversion curve was recorded. The influence of the FOV and scanned phantom dimensions is not statistically significant on the appearance of the calibration curve (RED ≥ 1.1). [ABSTRACT FROM AUTHOR]

Introduction: Gated tangential field-in-field (FIF) technique is used to lower the dose to organs at risk for breast cancer radiotherapy (RT). In this study, the authors investigated the accuracy of the delivered treatment plan with and without gating using a two-dimensional detector array for patient-specific verification purposes. Methods: In this study, a 6MV beams were used for the merged FIF RT (forward Intensity Modulated Radiation Therapy). The respiration signals for gated FIF delivery were obtained from the one-dimensional moving phantom using the real-time position management (RPM) system (Varian Medical Systems, Palo Alto, CA). RPM system used for four-dimensional computed tomography scanner light-speed, GE is based on an infrared camera to detect motion of external 6-point marker. The beams were delivered using a Clinac iX (Varian Medical Systems, Palo Alto, CA) with the multileaf collimator Millennium 120. The MapCheck2 (SunNuclear, Florida) was used for the evaluation of treatment plans. MapCheck2 was validated through a comparison with measurements from a farmer-type ion chamber. Gated beams were delivered using a maximum dose rate with varying duty cycles and analyzed the MapCheck2 data to evaluate treatment plan delivery accuracy. Results: Results of the gamma passing rate for relative and absolute dose differences for all ungated and gated beams were between 95.1% and 100%. Conclusion: Gated FIF technique can deliver an accurate dose to a detector during gated breast cancer RT. There is no significance between gated and ungated patient-specific quality assurance (PSQA); one can use ungated PSQA for verification of treatment plan delivery. [ABSTRACT FROM AUTHOR]

Installing of new solar capacities for electricity production has slowed down worldwide. To explore this trend, to assess opportunities for implementing solar potential, and to determine whether wider investment in solar capacities is possible, a comprehensive model is developed and applied to 28 EU countries and Serbia. Holistic "triangulation" approach encompasses a correlational multidimensional model, an economic analysis, and societal perspective. First, in a linear regression analysis, number and types of massive input variables were adjusted to maximize the level of explanation of the phenomenon and the significance of the input variables. Calculating 255 combinations of eight types of input data for four years, possible production of solar electricity in the 29 countries was quantified. Calculated results were subjected to complex analyses of sensitivity. Second, the balance between the production cost and market price of solar electricity was analyzed by the economic method of Levelised Cost of Electricity. Third, questionnaires and interviews revealed public opinion and expert opinion. Discussion of current situation and positive practice internationally and in Serbia covers regulatory, financial, and economic aspects, including an assessment of investment risks. In conclusion, interests and opportunities favour wider implementation of solar energy facilities for clean and renewable production of electricity. • This holistic study covers technology, economics, regulations, and sustainability. • A multidimensional linear regression model is developed and tested. • Levelised cost of electricity is considered in economic analysis. • Attitudes of citizens and experts are examined with questionnaire and interviews. • Solar energy should and can be more widely used for electricity production. [ABSTRACT FROM AUTHOR]

Urban environment could be considered as a complex biotechnical system. Multidisciplinary, interdisciplinary, and intradisciplinary analyses are required in order to achieve sustainable urban communities and healthier cities, especially in the era of climate changes. The main goal of this paper is to investigate, select, and review the theories and smart practices in negative effects of urban areas heat problems reduction and to define the objective function of the issue. The objective function could be treated as the force, with magnitude and direction of influence that operates in a certain space, which is considered to control certain factors and parameters, including time as a dimension. Spatial and temporal gradient of canyon effect are defined with nodes canyon effects interaction. The thermal islands are analyzed by its volume, sources of heat, thermal gradient, with the goal to select strategies to reduce the negative effects of heat islands. Positive smart practice in the world is discussed. The purpose of this study is to find, by literature review and by holistic methodological approach application, better practice and adequate solutions for building, energy, water, and carbon balance in urban environment. The results are expected in the movement towards the blue and green cities. [ABSTRACT FROM AUTHOR]

Soiling is a term used to describe the deposition of dust (dirt) on the solar modules, which reduces the amount of solar radiation that reaches the solar cells. This can cause a more difficult operation of the entire photovoltaic system and therefore generation of less electric energy. This paper presents the results of the influence of various pollutants commonly found in the air (carbon, calcium carbonate - CaCO3, and soil particles) on the energy efficiency of solar modules. Scanning electron microscope investigation of carbon powder, CaCO3, and soil particles which were applied to solar modules showed that the particles of carbon and CaCO3 are similar in size, while the space between the particles through which the light can pass, is smaller in carbon than in CaCO3. Dimensions of soil particles are different, and the space between the soil particles through which the light can pass is similar to CaCO3. Solar radiation more easily reaches the surface of solar modules soiled by CaCO3 and soil particles than the surface of the solar modules soiled by carbon. The efficiency of the module soiled by carbon on average decreases by 37.6%, the efficiency of the module soiled by CaCO3 by 6.7%, and the efficiency of the module soiled by soil particles by 6.8%, as compared to the clean solar module. The greatest influence on reducing the energy efficiency of solar modules by soiling exerts carbon, and the influence of CaCO3 and soil particles is similar. [ABSTRACT FROM AUTHOR]

We investigate the influence of sumanene modifications on its adsorption properties towards the hydrogen molecule. The benzylic positions of sumanene were substituted with boron and nitrogen atoms, which changed its hydrogen storage properties. H2 binding energies were calculated using the LMP2, DFT and DFT-D3 approaches with several exchange–correlation functionals and the results indicate a physisorption mechanism. Physisorption was confirmed by fragment analysis and special attention was paid to non-covalent interactions. All non-covalent interactions, based on reduced density gradient surfaces, were identified and calculated for better understanding of the adsorption mechanism. Moreover, the significance of charge separation by inducing boron and nitrogen atoms is emphasized and special attention is paid to the z-component of the dipole moment of sumanene derivatives. [ABSTRACT FROM AUTHOR]

In this paper comparison of experimentally obtained results of energy efficiency of photovoltaic solar plant of 2.08 kWp installed on the roof of the ASARS in Banja Luka in the real climate conditions in 2013 and 2014 are given. It was found that energy efficiency of photovoltaic solar plant from April till November 2013 was 12.28%, and in same period in 2014 was 13.03%. Also, it was found that the increase in the ambient temperature by 1 °C, photovoltaic solar plant efficiency decreases by 0.43% from April till November 2013, and by 0.27% in the same period in 2014. [ABSTRACT FROM AUTHOR]