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L. Lavrinovicha, J. Dirba, K. Sejejs and E. Kamolins

Abstract

The authors present a methodology for the calculation and optimisation of regulation laws that apply to electronically commutated synchronous motors with predefined characteristics. It is shown that the synchronous electronically commutated motors can provide predefined characteristics with the maintenance of high energy performance by simultaneously regulating supply voltage, excitation current and load angle.

Open access

N. Remez, A. Dychko, L. Yevtieieva, S. Kraychuk, N. Ostapchuk and J. Oliinyk

Abstract

The present paper provides a simple mathematical model that describes the synergistic interaction of environmental factors that occur in urban ecosystem. The model predicts the value of maximum synergistic action and the condition for its achievement, as well as implies the dependence of synergistic action on the intensity of the agents used and the proportion of irreversible damages after the combined effects. The developed mathematical model can be used to predict the accumulation of pollution in the ground layer of soil.

Open access

N. Mironova-Ulmane, A. Kuzmin, I. Sildos, L. Puust and J. Grabis

Abstract

Single-crystal, microcrystalline and nanocrystalline nickel oxides (NiO) have been studied by Raman spectroscopy. A new band at ~200 cm−1 and TO-LO splitting of the band at 350–650 cm−1 have been found in the spectra of single-crystals NiO(100), NiO(110) and NiO(111). The Raman spectra of microcrystalline (1500 nm) and nanocrystalline (13–100 nm) NiO resemble those of the single crystals. They all contain the two-magnon band at 1500 cm−1, indicating that the oxides remain at room temperature in the antiferromagnetic phase. Besides, a new sharp Raman band has been observed at 500 cm−1 in nanocrystalline NiO. Its temperature dependence suggests the magnetic origin of the band, possibly associated with the one-phonon–one-magnon excitation at the Brillouin zone centre.

Open access

J. Putrina, S. Olonkins, V. Bobrovs and J. Porins

Abstract

The article investigates dependence of EDFA performance on its operating conditions. First of all, the impact of changes in channel spacing on the quality of the amplifier signal and on the desired EDFA configuration is observed – three different values of channel spacing are considered – 37.5 GHz, 50 GHz and 100 GHz. Afterwards, the impact of EDFA positioning on the quality of the amplified signal and the desired configuration is assessed. Three different EDFA positioning scenarios are considered – when the EDFA is used as a power booster, as an in-line amplifier and as a preamplifier. In all cases, such configuration of the EDFA is found that can ensure bit-error ratio (BER) values below 1·10−9 in all channels of the system. To assess the performance of the amplifiers, power penalty values are obtained in respect to identical transmission systems but without amplification.

Open access

P. Dumenko, S. Kravchenko, A. Prokhorenko and D. Talanin

Abstract

Manufacturing companies of electronic control systems of diesel engines protect access to a program operation algorithm of the regulator that makes impossible adjustments and settings of its work, for example, at re-equipment or operational development of a new diesel engine. Therefore, it is important to acknowledge the solution of the scientific and technical problem of an effective and reliable system creation of electronic control of diesel fuel supply with an open program algorithm of its work. During the current research, settlement and experimental studies of a diesel engine supplied with a system of electronic control of a crankshaft rotation frequency developed by the authors show rather high adequacy in results. The dynamic mathematical model of the single-cylinder diesel engine supplied with the electronic regulator of rotation frequency has been developed and verified.

Open access

I. Lavrinovica, A. Supe and J. Porins

Abstract

The paper presents experimental study of the major erbium-doped fibre amplifier (EDFA) features such as gain at low signal and gain saturation by an application of different erbium-doped optical fibres (EDFs). The main objective of the research is to estimate how the performance of EDFA varies depending on the length of doped fibre, pumping configuration scheme, as well as excitation source power. It is shown that a high gain coefficient of 16–20 dB can be practically achieved.

Open access

M. Gavars, J. Rudnevs, G. Tribis and M. Danieks

Abstract

The aim of the research is to create a technological scheme for an industrial plant, which uses linseed oil (Pone oleum) paint as a finishing material upon workingwith coniferous wood components of different length andshape. On the basis of the technological scheme developed in the research, the prototype of the equipment will be produced at the factory of EKJU Ltd., with drying of products also being included.

Open access

Mohamed Bencheikh, Abdelmajid Maghnouj, Jaouad Tajmouati and Abdessamad Didi

Abstract

This study aims to investigate and evaluate the secondary photons characterizations under flattening filter (FF) for high radiotherapy quality in terms of fluence, energy fluence, energy fluence distribution, spectral distribution and angular spread distribution of secondary photons, which are mainly coming from primary collimator originated in the whole Linac head. However, the flattening filter illuminates the photons of low energy. After this component, the secondary photons of low energy are coming from flattening filter and secondary collimators that contaminate the dosimetry for deep tumor treatment.

Fluence profile, energy profile and angular spread of secondary photons decreased with FF volume reduction percent but energy distribution and spectral distribution kept almost constant with FF volume reduction. The FF volume reduction allows reducing the secondary photons emergent from FF in number and in energy and it permits to increase the radiotherapy efficiency by decreasing the photons contamination when the cancer is treating.

Open access

Zeinab Fardi and Payvand Taherparvar

Abstract

Permanent and temporary implantation of I-125 brachytherapy sources has become an official method for the treatment of different cancers. In this technique, it is essential to determine dose distribution around the brachytherapy source to choose the optimal treatment plan. In this study, the dosimetric parameters for a new interstitial brachytherapy source I-125 (IrSeed-125) were calculated with GATE/GEANT4 Monte Carlo code. Dose rate constant, radial dose function and 2D anisotropy function were calculated inside a water phantom (based on the recommendations of TG-43U1 protocol), and inside several tissue phantoms around the IrSeed-125 capsule. Acquired results were compared with MCNP simulation and experimental data. The dose rate constant of IrSeed-125 in the water phantom was about 1.038 cGy·h−1U−1 that shows good consistency with the experimental data. The radial dose function at 0.5, 0.9, 1.8, 3 and 7 cm radial distances were obtained as 1.095, 1.019, 0.826, 0.605, and 0.188, respectively. The results of the IrSeed-125 is not only in good agreement with those calculated by other simulation with MCNP code but also are closer to the experimental results. Discrepancies in the estimation of dose around IrSeed-125 capsule in the muscle and fat tissue phantoms are greater than the breast and lung phantoms in comparison with the water phantom. Results show that GATE/GEANT4 Monte Carlo code produces accurate results for dosimetric parameters of the IrSeed-125 LDR brachytherapy source with choosing the appropriate physics list. There are some differences in the dose calculation in the tissue phantoms in comparison with water phantom, especially in long distances from the source center, which may cause errors in the estimation of dose around brachytherapy sources that are not taken account by the TG43-U1 formalism.

Open access

Ramaa Lingaiah, Md Abbas Ali, Ummay Kulsum, Muhtasim Aziz Muneem, Karthick Raj Mani, Sharif Ahmed, Md. Shakilur Rahman and M Salahuddin

Abstract

Aim: To estimate the Gross Tumor Volume (GTV) using different modes (axial, helical, slow, KV-CBCT & 4D-CT) of computed tomography (CT) in pulmonary tumors.

Materials & Methods: We have retrospectively included ten previously treated case of carcinoma of primary lung or metastatic lung using Stereotactic Body Radiation Therapy (SBRT) in this study. All the patients underwent 4 modes of CT scan Axial, Helical, Slow & 4D-CT using GE discovery 16 Slice PET-CT scanner and daily KV-CBCT for the daily treatment verification. For standardization, all the patients underwent different modes of scan using 2.5 mm slice thickness, 16 detectors rows and field of view of 400mm. Slow CT was performed using axial mode scan by increasing the CT tube rotation time (typically 3 – 4 sec.) as per the breathing period of the patients. 4D-CT scans were performed and the entire respiratory cycle was divided into ten phases. Maximum Intensity Projections (MIP), Minimum Intensity Projections (MinIP) and Average Intensity Projections (AvIP) were derived from the 10 phases. GTV volumes were delineated for all the patients in all the scanning modes (GTVAX - Axial, GTVHL - Helical, GTVSL – Slow, GTVMIP -4DCT and GTVCB – KV-CBCT) in the Eclipse treatment planning system version 11.0 (M/S Varian Medical System, USA). GTV volumes were measured, documented and compared with the different modes of CT scans.

Results: The mean ± standard deviation (range) for MIP, slow, axial, helical & CBCT were 36.5 ± 40.5 (2.29 – 87.0), 35.38 ± 39.52 (2.1 – 82), 31.95 ± 37.29 (1.32 – 66.9), 28.98 ± 33.36 (1.01 – 65.9) & 37.16 ± 42.23 (2.29 – 92). Overall underestimation of helical scan and axial scan compared to MIP is 21% and 12.5%. CBCT and slow CT volume has a good correlation with the MIP volume.

Conclusion: For SBRT in lung tumors better to avoid axial and helical scan for target delineation. MIP is a still a golden standard for the ITV delineation, but in the absence of 4DCT scanner, Slow CT and KV-CBCT data may be considered for ITV delineation with caution.