http://hdl.handle.net/123456789/1 http://hdl.handle.net/123456789/5795 UTICAJ INTERAKCIJA UDALJENIH GALAKSIJA NA NJIHOVO NETERMALNO RADIO ZRAČENJE Pavlović, Mrina The studyofgalaxiesthroughhighredshiftsarekeytounderstandingthe evolutionofgalaxiesthroughcosmictimes.Assuchobjectsareverydifficultto observedirectly,theyaremainlyexaminedusingempiricallyderivedtoolssuchas the numerouscorrelationsbetweentheirdifferentparametriccharacteristics,one of thembeingthelinearrelationshipbetweenfar-infraredandradioemissionin star-forming galaxies,namedtheFarInfrared-Radio(FIR)Correlation.Although the correlationwasconsideredtobestableintermsoflinearity,recentworks, whichincludegalaxiesathighredshifts(0 < z< 6), showedalargedeviation from thecorrelationinthesesystems.Thegoalofthisdoctoraldissertationis an examinationofthephysicalprocessesthatleadtothiskindofbehavior.As a possiblecauseofthisevolution,wewillassumeforthefirsttime,andexamine interactionsbetweengalaxies(collisionsandcloseapproaches).Interactionsbe- tweengalaxiesleadtotheformationofshockwavesonlargescalesthatcanlead to changesintherelationshipbetweeninfraredandradioemissions.Ourhypoth- esis wastestedinseveralstadiumsandthemainresultsareasfollows:1.We developedmodelsoftheevolutionoftheFIRcorrelationwithredshiftasfunctions of thegalaxyinteractionrate.Wetestedthemodelsonasampleofgalaxieswith an alreadydeterminedmorphologyseparatelyfordiscgalaxiesandforgalaxies that haverecentlybeenorarecurrentlyinteracting-irregulargalaxies. 2. Inasmallsampleof34galaxiesthatwetookfrompaperMiettinenetal.(2017), it wasshownthatthereisanindicationthattheinteractionbetweengalaxiescan beresponsiblefortheevolutionofthecorrelationwiththeredshift. 3. Thenextanalysiswasperformedonamuchlargersampleofstar-forming galaxies takenfromCOSMOSfield,wherewedidnotfindanyevolutionofcorre- lation withtheredshift.Also,itwasshownthatthemeanvalueofthecorrelation parameter islowerinirregulargalaxiesthanindiskgalaxies. Although recentobservationsindicatedanevolutionoftheFIRcorrelation with redshift,theresultsofthisresearchfailedtoreproducethatevolutionand showedthattheFIRcorrelationisstablewithredshift.However,itwasalso shownthatduetotheinteractionofgalaxies,theevolutionoftheFIRcorrelation is possibleiftherepresentationofinteractingsystemsinthesampleishigher. Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/123456789/5794 SEMANTIC UNIFICATION AND SEARCHING OF BIOINFORMATICS DATABASES USING DATA MINING METHODS Veljković, Aleksandar Bioinformatics as a science of the future faces the problems of processing a large amount of data that is increasing every day. In addition to the problem of data storage, the challenge is also data analysis and the understanding of hidden relations between biological entities that are observed only after unifying data from different data sources. This thesis proposes a novel data model for the unification of heterogeneous data from multiple bioinformatics databases and a system architecture design for implementing software systems based on the proposed data model. Additionally, the thesis defines an automated pipeline for discovering new semantic similarity relations based on data mining methods using the data found in the proposed data model. The data model, software architecture, and automatic pipeline are evaluated using data from five real-world bioinformatics databases. The results demonstrate a high flexibility of the data model and the high efficiency of the software system implemented following the proposed architecture design. Sun, 01 Jan 2023 00:00:00 GMT http://hdl.handle.net/123456789/5793 IN- SITU DUST DETECTION USING RADIO ANTENNAS OF DIFFERENT SPACECRAFT - SPACE OBSERVATIONS AND MODELING Racković Babić, Kristina Interplanetary dust grains contain important information about the Solar System. Analyzing these particles is an important aspect of the heliosphere study. Dust impacts have been observed using radio and wave instruments onboard the spacecraft since the 1980s. The interaction between the impact-generated plasma cloud and antenna – spacecraft system elements generates the characteristic signal waveform. The present work focuses on the detection and interpretation of the dust generated signals from radio instruments onboard various spacecraft orbiting at 1 AU. In the first part of the thesis, we aim to develop a model which links the observed electric signals to the dust impact properties.We propose a new model which takes into account the effect of impact - ionization - charge collection and electrostatic-influence. Our model provides an analytical expression for the pulse. It allows us to measure the amount of total ion charge, the fraction of escaping charge, the rise timescale, and the relaxation timescale. The proposed model is simple and convenient for large data fitting. To validate the model, we use the Time Domain Sampler (TDS) subsystem of the STEREO/WAVES instrument, which generates high-cadence time series of voltage pulses for each monopole. Since the beginning of the STEREO mission in 2007, we have collected all the dust events detected by S/WAVES/TDS simultaneously on all three monopoles at 1 AU. Our study confirms that the rise time vastly exceeds the spacecraft’s short timescale of electron collection by the spacecraft. Aside from electron dynamics, we also obtained interesting results regarding the cloud’s electron temperature. The presented model provides an effective tool for analyzing vii dust waveforms, and is applicable for different space missions which investigate the distribution of dust particles, e.g., Solar Orbiter and Parker Solar Probe. In the second part of the thesis, we focus on the interstellar dust (ISD). Interplanetary and interstellar dust are the two main dust populations at 1 AU. Our objective is to search for interstellar dust by analyzing the data sets collected by STEREO and Wind, starting from the beginning of the missions. Between 2007 and 2012, while being at the solar minimum with a solar dipole pointing southward, all three spacecraft recorded ISD flux at 1 AU. However, before and after that period, the disappearance of the interstellar component was noticeable. The observed change of the impact rate suggests that the flux of interstellar dust at 1 AU varies with the solar cycle. Each time the magnetic dipole field changes its polarity during the solar cycle, small interstellar grains experience focusing or defocusing. Consequently, the dust grains are systematically deflected either towards, or away from the solar magnetic equator plane by the solar wind magnetic field which thus affects the dust dynamics and the total interstellar dust flux in the inner heliosphere. Our study provides the first quantitative description of the time variation of ISD flux at 1 AU. Sat, 01 Jan 2022 00:00:00 GMT http://hdl.handle.net/123456789/5792 PREBROJAVANJE KLASA EKVIVALENCIJE BULOVIH FUNKCIJA Carić, Marko In this dissertation, the problem of calculating the number of equiva- lence classes of Boolean functions is discussed. The difficulty of determining the number of equivalence classes increases sharply with the number of variables n. The motivation for choosing this topic lies in the fact that concrete numbers have been known so far only for relatively small values of n, although the problem itself was theoretically solved a long time ago. Let G be the group of permutations of the set Bn = {0, 1}n. The effect of the group G on scalar, Bn 7 → B1, that is, vectorial invertible Boolean functions, Bn 7 → Bn. Two scalar Boolean functions f (x) and g(x), defined on Bn, are considered equivalent with respect to the group G, i.e. f ∼ g, if for some σ ∈ G for every x ∈ Bn f (x) = g(σ(x)) holds. Two vector invertible Boolean functions f (x) and g(x), are considered equivalent with respect to the group G, i.e. f ∼ g, if for some pair (σ, ρ) ∈ G × G for each x ∈ Bn holds g(x) = ρ(f (σ(x))). The equivalence relation ∼ decomposes the set of all Boolean functions into equivalence classes. Equivalence of Boolean functions has significant applications in the logical synthesis of combinatorial circuits and in cryptography, especially in connection with the design of S-boxes. Let Un(G) and Vn(G) denote number of equivalence classes of scalar, i.e. vector invertible Boolean functions of n variables in relation to the group G. The numbers Un(G) and Vn(G) can be calculated relatively simply if the cycle index of the group G is known. The dissertation considers four groups G of permutations of the set Bn: • group S′ n induced by group Sn permutations of coordinates elements x = (x1, x2, . . . , xn) ∈ Bn, • group Gn, induced by permutations and complementations of coordinates, • group of GLn linear invertible transformations elements of the vector space Bn, i • group of AGLn affine invertible transformations elements Bn. If the permutation σ ∈ G has ik cycles of length k ⩾ 1, its cycle structure is i(σ) = (i1, i2, . . .). The cyclic index of the group G is the generatrix ZG(f1, f2, . . .) = 1 |G| X σ∈G Y k⩾1 f ik k of cycle structures of all permutations σ ∈ G. General expressions for cycle indices the four considered groups are known, but the cycle indices themselves, i.e. the numbers Un(G) and Vn(G), are practically calculated only for relatively small values, for e.g. n ⩽ 10. The dissertation presents original results in the field of enumeration of equiv- alence classes of Boolean functions in relation to these four groups of transfor- mations. A similar expression was derived for all four groups of transformations for the cycle index in the form of sum over partitions of the number n. Based on that expression and previously calculated tables, the cycle index is calculated much more efficiently. An overview of known results for relatively small n and new results in the thesis for larger n is shown in the following table: Number\ G S′ n Gn GLn AGLn Un(G) 11 → 33 10 → 32 8 → 31 10 → 31 Vn(G) 6 → 30 7 → 27 6 → 26 6 → 26 Specially, in the case of the permutation group S′ n, an effective direct procedure for calculating the number of equivalence classes that does not use a cycle index is shown, and is described in the third paper from the introductory chapter. The second part of the dissertation concerns monotone Boolean functions — scalar Boolean functions which satisfy the monotonicity condition (from x ⩽ y follows f (x) ⩽ f (y)). Let rn, i.e. dn (the n-th Dedekind number), denote the number of equivalence classes of monotone Boolean functions in relation to the group S′ n, that is, the total number of monotone Boolean functions of n variables. The difficulty of calculating the number rn increases rapidly with n, so that until recently the last calculated member of the sequence was r7. The procedure described in the dissertation is based on the Frobenius theorem, by which it was determined number r8. In doing so, the known value of the number d8 is used. The dissertation consists of the first - introductory chapter and the following three chapters. In the second chapter, theoretical terms related to the material from chapters 3 and 4 are introduced, and they refer to discrete mathematics, combinatorics and cycle indices of the considered four groups of transformations. Chapter 3 describes the procedure for calculating the cycle indices for the four considered groups of permutations, as well as numbers Un(G) and Vn(G) equivalence classes of Boolean functions in relation to these groups. First, common improvements for all four groups are considered, and then specific accelerations related to individual groups. These results are published in the second paper listed in the introductory chapter. In chapter 4, the problem of finding the number of equivalence classes of monotone Boolean functions is solved. First, a general expression for calculating the number rn is given based on the Frobenius theorem in the form of the sum (by partitions of the number n) of the number of fixed points of the permutation corresponding to the partition. After that, depending on the graphs corresponding to different partitions, different ways of calculating the number of fixed points for n ⩽ 8 are shown. The procedure based on which the number r8 was calculated, which also represents the original contribution of this dissertation is presented - see the first paper from the list from the introductory chapter. Applying a similar procedure, Pawelski [31] calculated r8 practically at the same time as the obtained result described in the dissertation. Sun, 01 Jan 2023 00:00:00 GMT