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.

Sotamuistomerkki Suomessa. Voiton ja tappion modaalista sovittelua

Väitöskirjani tarjoaa laajasti tietoa sotamuistomerkeistä koko Suomen alueelta. Työ purkaa suomalaisten sotamuistomerkkien ilmaisutapoja ja modaalisia keinoja, joilla taideteokset sovittelevat voitetun tai hävityn sodan tarinaa ja kokemuksellisia jännitteitä toisiinsa. Suurin osa analyysin kohteena olevista taideteoksista on pystytetty Suomen itsenäisyyden ajalla vapaudenpatsaiksi tai sankarihautojen, taisteluiden ja vakaumuksensa puolesta kuolleiden muistomerkeiksi. Tutkimus painottuu voiton ideologian vaikutukseen sotakuvaston muotoutumisessa. Avainkysymyksiä ovat, miten sotamuistomerkki viestittää poliittis-ideologisia tavoitteita tai miten muistomerkkien figuurien asennot, eleet ja attribuutit välittävät sotatarinan yhteisöllisiä sisältöjä. Tutkimus tarkentuu teosten modaalisiin piirteisiin ja merkityksenmuodostuksen vuorovaikutteisuuteen. Erikoishuomion kohteena ovat aiheiden sisällölliset ristiriidat ja ilmaisun murtumakohdat. Suurten teosmäärien ja aihetyyppien jaottelussa ja analysoimisessa on hyödynnetty ikonografian, kuvaretoriikan ja eleiden tutkimusta. Suomalaisen aineiston vertailukohtina ovat antiikin sotilasaiheinen taide, keskiaikainen Kristuksen kärsimyskuvasto sekä sotamuistomerkkiperinne Saksassa, Ranskassa, Yhdistyneessä kuningaskunnassa ja Amerikan yhdysvalloissa. Sotien muistokultin merkitysten avaamisessa käytetään diskurssianalyysin välineitä. Tutkimus osoittaa, että sotamuistomerkit rakentavat yhteisön turvallisuudentunnetta ja muokkaavat sotilasimagoa maskuliinisten ideaalien ja implisiittisen vihollis- tai vastakuvan varassa. Kansallisen paatoksen ohessa sotamuistomerkit vahvistavat sotilaiden aseveliaatetta ja luovat kuvaa rikkumattomasta yhteishengestä sekä kotirintamasta. Teokset tulkitsevat valmistumisaikansa usein ristiriitaista tunneilmapiiriä ja tulevaisuuden odotuksia sekä neuvottelevat paikallisesta erityisyydestä ja valtakysymyksistä. Veistosten modaaliset keinot suhteessa toimijarooleihin, kuten autonomisuuden korostus, tunteenomainen toiseen tukeutuminen tai sodan velvoitteisiin suuntautuminen perustuvat yleensä figuurien asentoihin. Sen sijaan figuurien eleet ja attribuutit, tärkeimpinä kypärä, ase, univormu ja lumipuku, tarkentavat suuntautumisen tavoitetta ja ideologista sanomaa. Koska sodassa on kyse vaikeasti käsiteltävistä väkivaltakulttuurin ilmiöistä, muistomerkeillä on hämärretty ja muokattu kuvaa historian tapahtumista. Siten teosten välittämät ideat uhrivalmiudesta ja tunteiden hillinnän velvoitteesta auttavat sotatraumojen ja surun kanavoimisessa sekä purkavat tapahtumiin liittyvää häpeää.

The duality of tactical thought : a study of how Swedish land forces' commanders view tactics in irregular warfare

This is a sociological study of the views of officers in the Swedish Army and its Amphibious Forces on tactics in Irregular Warfare (IW), in particular, Counterinsurgency (COIN). IW comprises struggles, where the military weaker part uses an indirect approach with smaller units and integrates the civilian and military dimensions in a violence spectrum including subversion, terrorism, Guerrilla Warfare and infantry actions. IW is the main armed warfare style in insurgencies. COIN is the combined political, military, economic, social and legal actions in counter insurgencies. Data has been collected by means of interviews with almost all (n =43) officers, who were either commanding battalions or rifle and manoeuvre companies while undergoing training for general warfare and international operations. The main theoretical and methodological inspiration is the traditional one for research on social fields, inaugurated by the French sociologist Pierre Bourdieu. The statistical technique used is Multiple Correspondence Analysis. As a background and context base, an inquiry inspired by the Begriffsgechichte (Conceptual History) tradition explores the genesis and development of understandings of the term Irregular Warfare. The research question is outlined as; “how can contemporary Swedish military thought on tactics in Irregular Warfare be characterized using descriptive patterns, mapped in relation to background factors and normative standards? The most significant findings are that there are two main opposing notions separating the officers’ views on tactics in Irregular Warfare: (1) a focus on larger, combat oriented and collectively operating military units versus smaller and larger, more intelligence oriented and dispersed operating units, and (2) a focus on military tasks and kinetic effects versus military and civilian tasks as well as “soft” effects. The distribution of these views can be presented as a two-dimensional space structured by the two axes. This space represents four categories of tactics, partly diverging from normative military standards for Counterinsurgency. This social space of standpoints shows different structural tendencies for background factors of social and cultural character, particularly dominant concerning military backgrounds, international mission experiences and civilian education. Compared to military standards for Counterinsurgency, the two tactical types characterized by a Regular Warfare mind-set stands out as counter-normative. Signs of creative thought on military practice and theory, as well as a still persistent Regular Warfare doxa are apparent. Power struggles might thus develop, effecting the transformation to a broadened warfare culture with an enhanced focus also on Irregular Warfare. The result does not support research results arguing for a convergence of military thought in the European transformation of Armed Forces. The main argument goes beyond tactics and suggests sociological analysis on reciprocal effects regarding strategy, operational art, tactics as well as leadership, concerning the mind-set and preferences for Regular, Irregular and Hybrid Warfare.

Critical infrastructure protection against cyber threats

A postgraduate seminar series with a title Critical Infrastructure Protection against Cyber Threats held at the Department of Military Technology of the National Defence University in the fall of 2013 and 2014. This book is a collection of some of talks that were presented in the seminar. The papers address origin of critical infrastructure protection, wargaming cyberwar in critical infrastructure defence, cyber-target categorization, supervisory control and data acquisition systems vulnerabilities, electric power as critical infrastructure, improving situational awareness of critical infrastructure and trust based situation awareness in high security cloud environment. This set of papers tries to give some insight to current issues of the network-centric critical infrastructure protection. The seminar has always made a publication of the papers but this has been an internal publication of the Finnish Defence Forces and has not hindered publication of the papers in international conferences. Publication of these papers in peer reviewed conferences has indeed been always the goal of the seminar, since it teaches writing conference level papers. We still hope that an internal publication in the department series is useful to the Finnish Defence Forces by offering an easy access to these papers.

Sotilaspolitiikka Kremlin Olympoksella. Venäjän sotilasreformin diskursiivinen rakentuminen venäläisessä sanomalehdistössä 2008–2012

Tutkimus käsittelee venäläisessä sanomalehdistössä esiintyvää keskustelua Venäjän sotilasreformista. Tutkimuksessa haluttiin selvittää, millaisia diskursseja keskustelussa käytetään sotilasreformin oikeuttamiseksi ja miten ne toimivat vallankäytön välineenä. Tutkimus on monitieteinen. Se antaa vastauksia kielitieteellisessä kehyksessä kielen ja diskurssin roolista päätöksenteossa, yhteiskuntatieteellisessä kehyksessä venäläisestä mediasta ja päätöksentekojärjestelmästä sekä sotatieteellisessä kehyksessä asevoimien kehityksestä ja sotilaspolitiikasta. Tutkimuksen primääriaineisto muodostuu 220 artikkelista, jotka kerättiin yhdeksästä venäläisestä sanomalehdestä vuosien 2008–2012 ajalta. Venäjän johtohenkilöt ja heitä tukevat sanomalehdet oikeuttivat sotilasreformia julkisessa keskustelussa ensisijaisesti viiden syyn avulla: uhkien lisääntymisellä, sodan kuvan muutoksella, asevoimien kalustollisella ja toiminnallisella jälkeenjääneisyydellä, henkilöstön osaamisen alhaisella tasolla ja tarpeella toiminnan järkeistykseen. Sotilasreformin päätöksiä oikeutettiin vetoamalla niiden huolelliseen suunnitteluun, henkilöstön asialliseen kohteluun ja taloudellisten asioiden vakauteen. Sanomalehdistössä esiintyi paljon toisistaan poikkeavia näkemyksiä kehitykseen tarvittavasta suunnasta. Suurin osa kritisoivista diskursseista keskittyi kritisoimaan reformin toteutusta, ei sen olemassaoloa. Kritiikki keskittyi tiedotuksen ja demokraattisen päätöksenteon puutteeseen sekä epäilyksiin reformin valmisteluprosessista. Venäjän asevoimia ja sotilaspolitiikkaa koskevaa uutisointia on ongelmallista tarkastella ilman diskurssikäytäntöjen huomiointia. Venäjän johdon ja sen legitimiteettiä vahvistavien sanomalehtien diskursiivisen vallankäytön tavoitteena on saada Venäjä näyttämään todellisuutta vahvemmalta ja yhtenäisemmältä. Vaikka venäläinen media ja siinä etenkin televisio ei ole vapaata, sanomalehdistö on verrattain hyvä tiedonlähde. Sen varsin monipuolinen omistajuus tutkimusaineiston rajauksen aikana mahdollisti erilaisten näkökulmien esillepääsyn. Analyyttisimmin sotilasreformista uutisoivat ne sanomalehdet, jotka eivät nähneet länsimaita Venäjän uhkana ja representoivat diskursseissaan liberalistisia arvoja kuten avoimuutta ja demokratiaa. Sanomalehdistön vaatimaton rooli venäläisessä mediakentässä heikentää kuitenkin sen vaikuttavuutta yleiseen mielipiteeseen. Sanomalehtien diskurssikäytäntöjen analysointi ideologioiden ja vallankäytön kautta voi tarjota mahdollisuuksia parantaa venäläisen valtionjohdon päätösten ennustettavuutta.

Defining the keyhole modes – the effects on the weld geometry and the molten pool behaviour in high power laser welding of stainless steels

Keyhole welding, meaning that the laser beam forms a vapour cavity inside the steel, is one of the two types of laser welding processes and currently it is used in few industrial applications. Modern high power solid state lasers are becoming more used generally, but not all process fundamentals and phenomena of the process are well known and understanding of these helps to improve quality of final products. This study concentrates on the process fundamentals and the behaviour of the keyhole welding process by the means of real time high speed x-ray videography. One of the problem areas in laser welding has been mixing of the filler wire into the weld; the phenomena are explained and also one possible solution for this problem is presented in this study. The argument of this thesis is that the keyhole laser welding process has three keyhole modes that behave differently. These modes are trap, cylinder and kaleidoscope. Two of these have sub-modes, in which the keyhole behaves similarly but the molten pool changes behaviour and geometry of the resulting weld is different. X-ray videography was used to visualize the actual keyhole side view profile during the welding process. Several methods were applied to analyse and compile high speed x-ray video data to achieve a clearer image of the keyhole side view. Averaging was used to measure the keyhole side view outline, which was used to reconstruct a 3D-model of the actual keyhole. This 3D-model was taken as basis for calculation of the vapour volume inside of the keyhole for each laser parameter combination and joint geometry. Four different joint geometries were tested, partial penetration bead on plate and I-butt joint and full penetration bead on plate and I-butt joint. The comparison was performed with selected pairs and also compared all combinations together.

Comparison of Different Concentrated Solar Power Collector Designs and Development of a Linear Fresnel Solar Collector Model

Concentrated solar power (CSP) is a renewable energy technology, which could contribute to overcoming global problems related to pollution emissions and increasing energy demand. CSP utilizes solar irradiation, which is a variable source of energy. In order to utilize CSP technology in energy production and reliably operate a solar field including thermal energy storage system, dynamic simulation tools are needed in order to study the dynamics of the solar field, to optimize production and develop control systems. The object of this Master’s Thesis is to compare different concentrated solar power technologies and configure a dynamic solar field model of one selected CSP field design in the dynamic simulation program Apros, owned by VTT and Fortum. The configured model is based on German Novatec Solar’s linear Fresnel reflector design. Solar collector components including dimensions and performance calculation were developed, as well as a simple solar field control system. The preliminary simulation results of two simulation cases under clear sky conditions were good; the desired and stable superheated steam conditions were maintained in both cases, while, as expected, the amount of steam produced was reduced in the case having lower irradiation conditions. As a result of the model development process, it can be concluded, that the configured model is working successfully and that Apros is a very capable and flexible tool for configuring new solar field models and control systems and simulating solar field dynamic behaviour.

Map of the United States and territories showing the extent of public surveys and military reservations, land grant R.R., rail roads, canals, and other details ...

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

Analyzing the Effects of the New Renewable Energy Policy in Russia on Investments into Wind, Solar and Small Hydro Power

This thesis presents an analysis of recently enacted Russian renewable energy policy based on capacity mechanism. Considering its novelty and poor coverage by academic literature, the aim of the thesis is to analyze capacity mechanism influence on investors’ decision-making process. The current research introduces a number of approaches to investment analysis. Firstly, classical financial model was built with Microsoft Excel® and crisp efficiency indicators such as net present value were determined. Secondly, sensitivity analysis was performed to understand different factors influence on project profitability. Thirdly, Datar-Mathews method was applied that by means of Monte Carlo simulation realized with Matlab Simulink®, disclosed all possible outcomes of investment project and enabled real option thinking. Fourthly, previous analysis was duplicated by fuzzy pay-off method with Microsoft Excel®. Finally, decision-making process under capacity mechanism was illustrated with decision tree. Capacity remuneration paid within 15 years is calculated individually for each RE project as variable annuity that guarantees a particular return on investment adjusted on changes in national interest rates. Analysis results indicate that capacity mechanism creates a real option to invest in renewable energy project by ensuring project profitability regardless of market conditions if project-internal factors are managed properly. The latter includes keeping capital expenditures within set limits, production performance higher than 75% of target indicators, and fulfilling localization requirement, implying producing equipment and services within the country. Occurrence of real option shapes decision-making process in the following way. Initially, investor should define appropriate location for a planned power plant where high production performance can be achieved, and lock in this location in case of competition. After, investor should wait until capital cost limit and localization requirement can be met, after that decision to invest can be made without any risk to project profitability. With respect to technology kind, investment into solar PV power plant is more attractive than into wind or small hydro power, since it has higher weighted net present value and lower standard deviation. However, it does not change decision-making strategy that remains the same for each technology type. Fuzzy pay-method proved its ability to disclose the same patterns of information as Monte Carlo simulation. Being effective in investment analysis under uncertainty and easy in use, it can be recommended as sufficient analytical tool to investors and researchers. Apart from described results, this thesis contributes to the academic literature by detailed description of capacity price calculation for renewable energy that was not available in English before. With respect to methodology novelty, such advanced approaches as Datar-Mathews method and fuzzy pay-off method are applied on the top of investment profitability model that incorporates capacity remuneration calculation as well. Comparison of effects of two different RE supporting schemes, namely Russian capacity mechanism and feed-in premium, contributes to policy comparative studies and exhibits useful inferences for researchers and policymakers. Limitations of this research are simplification of assumptions to country-average level that restricts our ability to analyze renewable energy investment region wise and existing limitation of the studying policy to the wholesale power market that leaves retail markets and remote areas without our attention, taking away medium and small investment into renewable energy from the research focus. Elimination of these limitations would allow creating the full picture of Russian renewable energy investment profile.

Productizing of advanced service for power plants

Työn tavoitteena on kehittää ABB:lle palvelutuote, jota voidaan tarjota voimalaitosasiakkaille. Uuden palvelutuotteen tulee vastata ABB:n uuden strategian linjauksiin. Palvelulla tarjotaan asiakkaille 1.1.2015 voimaan tulleen energiatehokkuuslain määrittelemien pakollisten toimenpiteiden suoritusta. Työssä kerätään, käsitellään ja analysoidaan tietoa voimalaitosasiakkaille suunnatun palvelun tuotteistamisprosessin päätöksenteon tueksi. Palvelutuotteen kehittämistä varten tutkitaan ABB:n nykyisiä palvelutuotteita, osaamista ja referenssi projekteja, energiatehokkuuslakia, voimalaitosten energiatehokkuus-potentiaalia ja erilaisia energiakatselmusmalleja. Päätöksenteon tueksi tehdään referenssiprojektina energia-analyysi voimalaitokselle, jossa voimalaitoksesta tehdään ipsePRO simulointiohjelmalla mallinnus. Mallinnuksen ja koeajojen avulla tutkitaan voimalaitoksen minimikuorman optimointia. Markkinatutkimuksessa selvitetään lainsäädännön vaikutusta, nykyistä markkinatilannetta, potentiaalisia asiakkaita, kilpailijoita ja ABB:n mahdollisuuksia toimia alalla SWOT–analyysin avulla. Tutkimuksen tulosten perusteella tehdään päätös tuotteistaa voimalaitoksille palvelutuote, joka sisältää kaikki toimet energiatehokkuuslain asettamien vaatimusten täyttämiseen yrityksen energiakatselmuksen vastuuhenkilön, energiakatselmuksen ja kohdekatselmuksien teon osalta. Lisäksi työn aikana Energiavirasto myönsi ABB:lle pätevyyden toimia yrityksen energiakatselmuksen vastuuhenkilönä, mikä on edellytyksenä palvelun tarjoamiselle.

The role of nuclear power in the future energy system

Currently widely accepted consensus is that greenhouse gas emissions produced by the mankind have to be reduced in order to avoid further global warming. The European Union has set a variety of CO2 reduction and renewable generation targets for its member states. The current energy system in the Nordic countries is one of the most carbon free in the world, but the aim is to achieve a fully carbon neutral energy system. The objective of this thesis is to consider the role of nuclear power in the future energy system. Nuclear power is a low carbon energy technology because it produces virtually no air pollutants during operation. In this respect, nuclear power is suitable for a carbon free energy system. In this master's thesis, the basic characteristics of nuclear power are presented and compared to fossil fuelled and renewable generation. Nordic energy systems and different scenarios in 2050 are modelled. Using models and information about the basic characteristics of nuclear power, an opinion is formed about its role in the future energy system in Nordic countries. The model shows that it is possible to form a carbon free Nordic energy system. Nordic countries benefit from large hydropower capacity which helps to offset fluctuating nature of wind power. Biomass fuelled generation and nuclear power provide stable and predictable electricity throughout the year. Nuclear power offers better energy security and security of supply than fossil fuelled generation and it is competitive with other low carbon technologies.

Promoting Growth in the Use of Bioenergy in Europe by Converting Existing Coal-Fired Power Plants to Biomass

Repowering existing power plants by replacing coal with biomass might offer an interesting option to ease the transition from fossil fuels to renewable energy sources and promote a fur-ther expansion of bioenergy in Europe, on account of the potential to decrease greenhouse gas emissions, as well as other pollutants (SOx, NOx, etcetera). In addition, a great part of the appeal of repowering projects comes from the opportunity to reuse the vast existing invest-ment and infrastructure associated with coal-based power generation. Even so, only a limited number of experiences with repowering are found. Therefore, efforts are required to produce technical and scientific evidence to determine whether said technology might be considered feasible for its adoption within European conditions. A detailed evaluation of the technical and economic aspects of this technology constitutes a powerful tool for decision makers to define the energy future for Europe. To better illustrate this concept, a case study is analyzed. A Slovakian pulverized coal plant was used as the basis for determining the effects on perfor-mance, operation, maintenance and cost when fuel is shifted to biomass. It was found that biomass fuel properties play a crucial role in plant repowering. Furthermore, results demon-strate that this technology offers renewable energy with low pollutant emissions at the cost of reduced capacity, relatively high levelized cost of electricity and sometimes, a maintenance-intensive operation. Lastly, regardless of the fact that existing equipment can be reutilized for the most part, extensive additions/modifications may be required to ensure a safe operation and an acceptable performance.

Optimization of a dynamic district heating power plant

The purpose of this Thesis is to find the most optimal heat recovery solution for Wärtsilä’s dynamic district heating power plant considering Germany energy markets as in Germany government pays subsidies for CHP plants in order to increase its share of domestic power production to 25 % by 2020. Different heat recovery connections have been simulated dozens to be able to determine the most efficient heat recovery connections. The purpose is also to study feasibility of different heat recovery connections in the dynamic district heating power plant in the Germany markets thus taking into consideration the day ahead electricity prices, district heating network temperatures and CHP subsidies accordingly. The auxiliary cooling, dynamical operation and cost efficiency of the power plant is also investigated.

Power efficiency estimation and simulation of different control methods for the rotary screw compressor

Nowadays the energy efficiency has become one of the most concerned topics. Compressors are the equipment, which is very common in industry. Moreover, they tend to operate during long cycles and therefore even small decrease in power consumption can significantly reduce electricity costs during the year. And therefore it is important to investigate ways of increasing the energy efficiency of the compressors. In the thesis rotary screw compressor alongside with different control approaches is described. Simulation models for various control types of rotary screw compressor are developed. Analysis of laboratory equipment is conducted and results are compared with simulation. Suggestions of the real laboratory equipment improvement are given.