Results 1 - 10 of 68
Results 1 - 10 of 68. Search took: 0.023 seconds
|Sort by: date | relevance|
[en] Structure and such properties of Al + 6% Li aluminium alloy with rare earth metals as oxidation resistance, thermal and thermodynamic stability has been defined for the first time. It has been shown that rare earth metals increase the solidity, improve thermophysical characteristics of Al + 6% Li aluminium alloy. The oxidation mechanism of Al + 6% Li aluminium alloy with rare earth metals and their influence on oxidation process has been determined. Phase composition of oxidation products has been defined. The mechanism of rare earth metals action as effective anode addition which improve corrosion resistance of Al + 6% Li aluminium alloy with rare earth metals in the medium of NaCl electrolyte has been revealed for the first time. It has been shown that with increasing of chloride-ion concentration in electrolyte the corrosion rate increases regardless on composition. Electrochemical characteristics of corrosion process of Al + 6% Li aluminium alloy alloyed by rare earth metals have been established.
[en] Thermal and aerodynamic parameters of air distribution of a mobile layer of firm particles and regularity of temperature change of a mobile layer of raw materials in the direction of the rotating drum of a cylindrical form are revealed. The analytical equation of uniform distribution of air taking into account regularity of dimensions of cross section and static pressure for the purpose of determination of the area of openings of an air dust is removed and is offered. The mathematical model of definition of a gradient of temperature in the course of decarbonization of the studied solid waste of aluminium production, as well as change of concentration of carbon at various values of thermal parameters of operating volume of the furnace of roasting is developed.
[en] A concept of micro nuclear reactor with supercritical CO2(S-CO2) Brayton cycle namely KAIST Micro Modular Reactor (MMR) with 12MWe power output is being developed to serve as a distributed power source for remote region. In order to successfully develop MMR, issues of bearing capacity for shaft levitation have to be resolved. In order to support a shaft for 12MWe system the magnetic bearing is suggested to be suitable instead of gas foil bearing which has lower levitation force. However, several previous studies on the magnetic bearing showed that instability issues exist under high speed operating with high pressure fluid conditions. Therefore, controlling magnetic bearing instability becomes an important issue for the realization of MMR The purposes of this research is to analyze instability of the magnetic bearing under S-CO2 condition and propose functional requirements of the magnetic bearing. The shaft with magnetic bearings and operating under high pressure fluid is analyzed. In addition, the analysis results can be used for predicting the instability. Based on the results, a magnetic bearing test rig is constructed. By comparing experimental data to the analysis results, the analysis model is verified
[en] The dissertation is initiated to the development of optimal methods for obtaining new thermoelectric materials of the Zintl phases, of the Yb14MnSb11 systems and its Yb14-xLnxMnSb11 solid solutions, where Ln is La, Nd and Sm; x=0.1-0.9. The single - crystals have a tetragonal structure and lattice parameters depend on the composition. In case when x=0.5, the additive enters to the crystal lattice. The melting process of all obtained 20 alloys proceeds with decomposition, melting points, thermal expansion coefficients and Debye temperatures of them are determined. (author)
[en] The Compressed Baryonic Matter experiment (CBM) at FAIR and the NA61/SHINE experiment at CERN SPS aim to study the area of the QCD phase diagram at high net baryon densities and moderate temperatures using heavy-ion collisions. The FAIR and SPS accelerators cover energy ranges 2-11 and 13-150 GeV per nucleon respectively in laboratory frame for heavy ions up to Au and Pb. One of the key observables to study the properties of a matter created in such collisions is an anisotropic transverse flow of particles. In this work, the performance of the CBM experiment for anisotropic flow measurements is studied with Monte-Carlo simulations using gold ions at SIS-100 energies employing different heavy-ion event generators. Also, procedures for centrality estimation and charged hadron identification are described and corresponding frameworks are developed. The measurement of the reaction plane angle is performed with Projectile Spectator Detector (PSD), which is a hadron calorimeter located at a very forward angle. To prevent radiation damage by the high-intensity ion beam, the PSD has a hole in the center to let the beam pass through. Various combinations of CBM detector subsystems are used to investigate the possible systematic biases in flow and centrality measurements. Effects of detector azimuthal non uniformity and the PSD beam hole size on physics performance are studied. The resulting performance of CBM for flow measurements is demonstrated for identified charged hadron anisotropic flow as a function of rapidity and transverse momentum in different centrality classes. The measurement techniques developed for CBM were also validated with the experimental data recently collected by the NA61/SHINE experiment at CERN SPS for Pb+Pb collisions at the beam momenta 30A GeV/c. Compared to the existing data from the NA49 experiment at the CERN SPS, the new data allows for a more precise measurement of anisotropic flow harmonics. The fixed target setup of NA61/SHINE also allows extending flow measurements available from the STAR at the RHIC beam energy scan (BES) program to a wide rapidity range up to the forward region where the projectile nucleon spectators appear. In this thesis, an analysis of the anisotropic flow harmonics in Pb+Pb collisions at beam momenta 30A GeV/c collected by the NA61/SHINE experiment in the year 2016 is presented. Flow coefficients are measured relative to the spectator plane estimated with the Projectile Spectators Detector (PSD). The flow coefficients are obtained as a function of rapidity and transverse momentum in different classes of collision centrality. The results are compared with the corresponding NA49 data and the measurements from the RHIC BES program.
[en] Processing of borosilicate raw material with nitric and acetic acids and sintering with NaOH and calcium and natrium chlorides has been studied. The mechanisms which occur at decomposition of borosilicate ores have been studied as well. The obtained results have been confirmed by means of chemical and physicochemical analysis methods. The flowsheet of processing of boron comprising ores with using of various reagents has been developed.
[en] The main regularities of change of heat capacity and change of thermodynamic functions (enthalpy, entropy, Gibbs energy) of AF 2.18 alloy with calcium, strontium and barium depending on temperature and quantity of alloying component have been determined. It has been shown that with temperature increasing the heat capacity, entropy and enthalpy of AF 2.18 alloy with calcium, barium and strontium increases and the Gibbs energy of alloys decreases. With increasing of calcium, strontium and barium portion in AF alloy the entropy and enthalpy increases and value of Gibbs energy decreases.
[en] The main physicochemical characteristics of obtaining of cryolite-alumina concentrates and argyle from siallites of Ziddi Deposit and waste of aluminium slurry fields by sintering method have been determined. Physicochemical parameters of joint processing of siallites and coal ash with waste of aluminium slurry fields have been defined.
[en] This study aims to investigate quantitatively and qualitatively the internal absorbed dose in radiotherapy breast cancer comparing a measured dose by radiochromic film with calculated dose by Treatment Planning System (TPS) at an anthropometric and anthropomorfic female thorax phantom. The thorax phantom was constructed and validated by the Núcleo de Radiações Ionizantes (NRI) UFMG research group. The phantom was elaborated by means of equivalent tissue materials with attenuation properties similar to human biological tissues. Materials such as elastin, vegetable oil and animal bone were used to mimic a skin, adipose tissue ribs and spine. The reproducibility of the radiation interaction phenomena with patient was the purpose of the NRI group simulator. The breast radiotherapy treatment plan was performed according to images acquired at computed tomography (TC). Different techniques of radiotherapy were used, like follows: three-dimensional conformational RT (3DCRT), static intensity modulated radiotherapy (sIMRT) and intensity modulated arc therapy (IMAT) for this research. The treatment planning complexity and dose delivery capacity increases from 3DCRT to IMAT. The availability of such technologies vary between radiotherapy services. In the treatment planning process, the left breast was considered as planning target volume (PTV) and the lungs, heart and contralateral breast as organs at risk (OARs). The parameters for the calculation of the dose were not the same for all experiments due to the different modalities involved. The dosimetry was performed with the radiochromic films EBT2 and EBT3. The definition of the calibration curves was fundamental to correlate the absorbed dose with the intensity of the red component in the scanned films. Two-dimensional absolute dose distributions were obtained with the radiochromic films in each case. Through the two-dimensional dose maps, it was possible to identify high-dose regions (hot spots) and low dose (cold spots) in relation to the prescribed dose. Radiation internal transport phenomena contributing to the additional dose delivery were recorded in the radiochromic films. These results demonstrate the indispensability of radiochromic films and suggest the relevance of an anthropomorphic and anthropometric phantom in routine quality assurance (QA) in radiotherapy services. Therefore, it is clear the need to continue this research. (author)
[en] The analyses of the transport and interaction of the heavy-ions is generally performed by using the computational code of Monte Carlo (MC) method and nuclear reaction model. In this study, enhancement of the parameterization of the total reaction crosssection model for the nucleus-nucleus collision was performed to improve the accuracy of the heavy-ion transport calculation. From the observation of the experimental data, a trend of a linear relation between mass difference between target and projectile nucleus and total reaction cross-section is expected in the energy range over 10 MeV/n. Therefore the parameterization of the total reaction cross-section model used in the MC codes for the heavy-ion transport calculation was modified to reflect this trend. The parameterization of total reaction cross-section is modified with the modification of asymmetry term and the correction factor. This proposed parameterization is based on the Kox and Shen model. The asymmetry in the transparency term of the Shen model was modified to reflect the neutron excess of the target and projectile. The correction factor is estimated with the mass difference between the projectile and target nucleus based on the observation of the experimental data on the total reaction cross-section of the nucleus-nucleus collision of the heavy-ions. As a result, the modified parameterization of the total reaction cross-section was proposed and shows a good agreement with the experiments than the original parameterization of the model