Minimizing Conducted RF-Emissions in Switch Mode Power Supplies Using Spread-Spectrum Techniques

Switching power supplies are usually implemented with a control circuitry that uses constant clock frequency turning the power semiconductor switches on and off. A drawback of this customary operating principle is that the switching frequency and harmonic frequencies are present in both the conducted and radiated EMI spectrum of the power converter. Various variable-frequency techniques have been introduced during the last decade to overcome the EMC problem. The main objective of this study was to compare the EMI and steady-state performance of a switch mode power supply with different spread-spectrum/variable-frequency methods. Another goal was to find out suitable tools for the variable-frequency EMI analysis. This thesis can be divided into three main parts: Firstly, some aspects of spectral estimation and measurement are presented. Secondly, selected spread spectrum generation techniques are presented with simulations and background information. Finally, simulations and prototype measurements from the EMC and the steady-state performance are carried out in the last part of this work. Combination of the autocorrelation function, the Welch spectrum estimate and the spectrogram were used as a substitute for ordinary Fourier methods in the EMC analysis. It was also shown that the switching function can be used in preliminary EMC analysis of a SMPS and the spectrum and autocorrelation sequence of a switching function correlates with the final EMI spectrum. This work is based on numerous simulations and measurements made with the prototype. All these simulations and measurements are made with the boost DC/DC converter. Four different variable-frequency modulation techniques in six different configurations were analyzed and the EMI performance was compared to the constant frequency operation. Output voltage and input current waveforms were also analyzed in time domain to see the effect of the spread spectrum operation on these quantities. According to the results presented in this work, spread spectrum modulation can be utilized in power converter for EMI mitigation. The results from steady-state voltage measurements show, that the variable-frequency operation of the SMPS has effect on the voltage ripple, but the ripple measured from the prototype is still acceptable in some applications. Both current and voltage ripple can be controlled with proper main circuit and controller design.

Breviarium Fratrum Praedicatorum (MS C.IV.10)

Two probably originally distinct but roughly contemporary books (I-II, copied by three scribes, A-C): A psalter and a Dominican breviary. Complete critical and codicological description of the book and its contents available in the Codices Fennici -database.

Contents: I: Psalter: Fols. 7r–76va, Psalter, with additional hymns, concluding with Te Deum; Fols. 76vb–77vb, the Athanasian Creed; Fols. 77vb–80v, litany and other prayers. II: Dominican breviary: Fols. 1r–6v, English Dominican calendar (Jan.–Dec.); Fols. 81r–242v, 276r–312r, proprium de tempore (defect), from the First Advent to the First Sunday after Trinity, and from septuagesima in mensis Augusti to the 25th Sunday after Trinity; Fols. 313ra–318v, Office for the dedication of a church; Fols. 243r–275v, 319r–334v, 353r–v, 335r–352v, 354r–371r, proprium de sanctis (defect), from the beginning up to the office of Mary Magdalene, with a misplaced leaf, fol. 353, at translatio B. Dominici, and, after several missing gatherings, the end of commune sanctorum; Fol. 371v, originally empty, with office for St Ursula added in a saec. XIV hand.

Surface studies of limestones and dolostones : characterisation using various techniques and batch dissolution experiments with hydrochloric acid solutions

In this thesis, stepwise titration with hydrochloric acid was used to obtain chemical reactivities and dissolution rates of ground limestones and dolostones of varying geological backgrounds (sedimentary, metamorphic or magmatic). Two different ways of conducting the calculations were used: 1) a first order mathematical model was used to calculate extrapolated initial reactivities (and dissolution rates) at pH 4, and 2) a second order mathematical model was used to acquire integrated mean specific chemical reaction constants (and dissolution rates) at pH 5. The calculations of the reactivities and dissolution rates were based on rate of change of pH and particle size distributions of the sample powders obtained by laser diffraction. The initial dissolution rates at pH 4 were repeatedly higher than previously reported literature values, whereas the dissolution rates at pH 5 were consistent with former observations. Reactivities and dissolution rates varied substantially for dolostones, whereas for limestones and calcareous rocks, the variation can be primarily explained by relatively large sample standard deviations. A list of the dolostone samples in a decreasing order of initial reactivity at pH 4 is: 1) metamorphic dolostones with calcite/dolomite ratio higher than about 6% 2) sedimentary dolostones without calcite 3) metamorphic dolostones with calcite/dolomite ratio lower than about 6% The reactivities and dissolution rates were accompanied by a wide range of experimental techniques to characterise the samples, to reveal how different rocks changed during the dissolution process, and to find out which factors had an influence on their chemical reactivities. An emphasis was put on chemical and morphological changes taking place at the surfaces of the particles via X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). Supporting chemical information was obtained with X-Ray Fluorescence (XRF) measurements of the samples, and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) measurements of the solutions used in the reactivity experiments. Information on mineral (modal) compositions and their occurrence was provided by X-Ray Diffraction (XRD), Energy Dispersive X-ray analysis (EDX) and studying thin sections with a petrographic microscope. BET (Brunauer, Emmet, Teller) surface areas were determined from nitrogen physisorption data. Factors increasing chemical reactivity of dolostones and calcareous rocks were found to be sedimentary origin, higher calcite concentration and smaller quartz concentration. Also, it is assumed that finer grain size and larger BET surface areas increase the reactivity although no certain correlation was found in this thesis. Atomic concentrations did not correlate with the reactivities. Sedimentary dolostones, unlike metamorphic ones, were found to have porous surface structures after dissolution. In addition, conventional (XPS) and synchrotron based (HRXPS) X-ray Photoelectron Spectroscopy were used to study bonding environments on calcite and dolomite surfaces. Both samples are insulators, which is why neutralisation measures such as electron flood gun and a conductive mask were used. Surface core level shifts of 0.7 ± 0.1 eV for Ca 2p spectrum of calcite and 0.75 ± 0.05 eV for Mg 2p and Ca 3s spectra of dolomite were obtained. Some satellite features of Ca 2p, C 1s and O 1s spectra have been suggested to be bulk plasmons. The origin of carbide bonds was suggested to be beam assisted interaction with hydrocarbons found on the surface. The results presented in this thesis are of particular importance for choosing raw materials for wet Flue Gas Desulphurisation (FGD) and construction industry. Wet FGD benefits from high reactivity, whereas construction industry can take advantage of slow reactivity of carbonate rocks often used in the facades of fine buildings. Information on chemical bonding environments may help to create more accurate models for water-rock interactions of carbonates.

Forecasting financial weather - can we foresee market sentiment? Spectrum of stock price behavior - NYSE case study

The desire to create a statistical or mathematical model, which would allow predicting the future changes in stock prices, was born many years ago. Economists and mathematicians are trying to solve this task by applying statistical analysis and physical laws, but there are still no satisfactory results. The main reason for this is that a stock exchange is a non-stationary, unstable and complex system, which is influenced by many factors. In this thesis the New York Stock Exchange was considered as the system to be explored. A topological analysis, basic statistical tools and singular value decomposition were conducted for understanding the behavior of the market. Two methods for normalization of initial daily closure prices by Dow Jones and S&P500 were introduced and applied for further analysis. As a result, some unexpected features were identified, such as a shape of distribution of correlation matrix, a bulk of which is shifted to the right hand side with respect to zero. Also non-ergodicity of NYSE was confirmed graphically. It was shown, that singular vectors differ from each other by a constant factor. There are for certain results no clear conclusions from this work, but it creates a good basis for the further analysis of market topology.

Codex Westh (MS C.III.19, kirkollinen käsinkirjoitettu kokoomanide)

Koodeksiin sisältyy kolme tekstikokonaisuutta. Ydinosan muodostavat suomalainen kirkkokäsikirja ja messu eli jumalanpalvelusjärjestys, joilla on oma, alkuperäinen sivunumerointinsa. Kolmas kokonaisuus on suomennos saksalaisen Urbanus Rhegiuksen laatimasta sielunhoidon opaskirjasta Sieluin vahvistus, lohutos ja lääkitys.

Graduale (MS C.III.36, "Ilmajoen Graduale II")

A very small gradual and hymnary, for the most part copied in the last years of the sixteenth century or in the first quarter of the seventeenth. Assuming that Henricus Jacobi indeed signed his name in the sixteenth century (as Kurvinen reports), some of the manuscript was copied in that century: in lieu of a more accurate indicator the date of the manuscript appears to fall between 1589 and Mathias Benedicti's additions in 1635. The book was kept, perhaps even copied but certainly used, at Ilmajoki from the seventeenth century, and came from there to the University Library.

Antiphonarium (MS A.ö.II.29, Ilmajoen antifonarium)

Complete critical and codicological description of the book and its contents available in the Codices Fennici -database.

Psalterium Davidicum (MS C.IV.24)

Complete critical and codicological description of the book and its contents available in the Codices Fennici -database.

Graduale (MS A.ö.II.55, Ilmajoen graduale)

A graduale (defect) from Ilmajoki. Written in three parts, part I (fols. 1-134) dating probably from the 1540's, part II (fols. 135-140) probably from the 1550's and part III (fols. 141-194) from the 1530's.

Graduale (MS Coll. 762.3)

A Lutheran gradual copied apparently by one scribe at the end of the sixteenth century and probably repaired (fol. 29) in the beginning of the seventeenth century.

Graduale (MS C.ö.III.17)

A Lutheran gradual from Kalanti. As covers used a fragment of the Liturgical calendar of the Diocese of Turku, Saec. XIV 2/2, Diocese of Turku.

Legendarium (MS C.ö.I.1)

Much of the manuscript is taken up by a collection Sunday sermons and by a selection from Legenda Aurea. The manuscript features several scribes and may be a result of compiling text from different sources.

Summa Theologiae (MS Coll. 762.2)

An abridgement or selections from Thomas Aquinas, Summa theologiae. The text strongly modifies and abridges the original.

Sermones de tempore et de sanctis (MS C.ö.I.6)

Complete critical and codicological description of the book and its contents available in the Codices Fennici -database.

Missale (MS C.ö.IV.7, "Oripään missale I")

Complete critical and codicological description of the book and its contents available in the Codices Fennici -database.