897 resultados para Distributed power generation


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Inducible defenses, which provide enhanced resistance after initial attack, are nearly universal in plants. This defense signaling cascade is mediated by the synthesis, movement, and perception of jasmonic acid and related plant metabolites. To characterize the long-term persistence of plant immunity, we challenged Arabidopsis (Arabidopsis thaliana) and tomato (Solanum lycopersicum) with caterpillar herbivory, application of methyl jasmonate, or mechanical damage during vegetative growth and assessed plant resistance in subsequent generations. Here, we show that induced resistance was associated with transgenerational priming of jasmonic acid-dependent defense responses in both species, caused caterpillars to grow up to 50% smaller than on control plants, and persisted for two generations in Arabidopsis. Arabidopsis mutants that are deficient in jasmonate perception (coronatine insensitive1) or in the biogenesis of small interfering RNA (dicer-like2 dicer-like3 dicer-like4 and nuclear RNA polymerase d2a nuclear RNA polymerase d2b) do not exhibit inherited resistance. The observation of inherited resistance in both the Brassicaceae and Solanaceae suggests that this trait may be more widely distributed in plants. Epigenetic resistance to herbivory thus represents a phenotypically plastic mechanism for enhanced defense across generations.

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The performance of magnetic nanoparticles is intimately entwined with their structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique way of engineering the magnetic response by modifying the strength of the dipolar interactions between particles. Here we report on an experimental and theoretical analysis of magnetic hyperthermia, a rapidly developing technique in medical research and oncology. Experimentally, we demonstrate that single-domain cubic iron oxide particles resembling bacterial magnetosomes have superior magnetic heating efficiency compared to spherical particles of similar sizes. Monte Carlo simulations at the atomic level corroborate the larger anisotropy of the cubic particles in comparison with the spherical ones, thus evidencing the beneficial role of surface anisotropy in the improved heating power. Moreover we establish a quantitative link between the particle assembling, the interactions and the heating properties. This knowledge opens new perspectives for improved hyperthermia, an alternative to conventional cancer therapies.

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The noise power spectrum (NPS) is the reference metric for understanding the noise content in computed tomography (CT) images. To evaluate the noise properties of clinical multidetector (MDCT) scanners, local 2D and 3D NPSs were computed for different acquisition reconstruction parameters.A 64- and a 128-MDCT scanners were employed. Measurements were performed on a water phantom in axial and helical acquisition modes. CT dose index was identical for both installations. Influence of parameters such as the pitch, the reconstruction filter (soft, standard and bone) and the reconstruction algorithm (filtered-back projection (FBP), adaptive statistical iterative reconstruction (ASIR)) were investigated. Images were also reconstructed in the coronal plane using a reformat process. Then 2D and 3D NPS methods were computed.In axial acquisition mode, the 2D axial NPS showed an important magnitude variation as a function of the z-direction when measured at the phantom center. In helical mode, a directional dependency with lobular shape was observed while the magnitude of the NPS was kept constant. Important effects of the reconstruction filter, pitch and reconstruction algorithm were observed on 3D NPS results for both MDCTs. With ASIR, a reduction of the NPS magnitude and a shift of the NPS peak to the low frequency range were visible. 2D coronal NPS obtained from the reformat images was impacted by the interpolation when compared to 2D coronal NPS obtained from 3D measurements.The noise properties of volume measured in last generation MDCTs was studied using local 3D NPS metric. However, impact of the non-stationarity noise effect may need further investigations.

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The energy system of Russia is the world's fourth largest measured by installed power. The largest are that of the the United States of America, China and Japan. After 1990, the electricity consumption decreased as a result of the Russian industry crisis. The vivid economic growth during the latest few years explains the new increase in the demand for energy resources within the State. In 2005 the consumption of electricity achieved the maximum level of 1990 and continues to growth. In the 1980's, the renewal of power facilities was already very slow and practically stopped in the 1990's. At present, the energy system can be very much characterized as outdated, inefficient and uneconomic because of the old equipment, non-effective structure and large losses in the transmission lines. The aim of Russia's energy reform, which was started in 2001, is to achieve a market based energy policy by 2011. This would thus remove the significantly state-controlled monopoly in Russia's energy policy. The reform will stimulateto decrease losses, improve the energy system and employ energy-saving technologies. The Russian energy system today is still based on the use of fossil fuels, and it almost totally ignores the efficient use of renewable sources such as wind, solar, small hydro and biomass, despite of their significant resources in Russia. The main target of this project is to consider opportunities to apply renewable energy production in the North-West Federal Region of Russia to partly solve the above mentioned problems in the energy system.

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Focus of this thesisis made on development of electricity sector of Russian North-West. The objective was to determine the most likely scenarios for development of the most critical (western) part of Interregional Power System of North-West, from where the most part of Russian electricity exports to the countries of European Union take place. For this purpose all the involved sides were analyzed: generation, transmission system and electricity consumption in different regions of Russian North-West. The analysis was performed through investigation of existing generation andtransmission capacities and plans for their development to be performed by the generation and transmission companies operating in the region. Principles of Russian electricity sector restructuring and electricity market design are also discussed as well as factors that may influence on future electricity price in the region.

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Työn tarkoituksena on tarkastella Euroopan siirtymätalousalueelta kotimaisen biopoltto-ainevoimalaitoksen kilpailukykyä potentiaalisimmiksi markkinakohteiksi arvioitujen nykyisten Eu-valtioiden osalta. Työ tehdään osana kokoluokaltaan 3,5 MWth/1,0 MWe pienvoimalaitoksen tuotekehityshanketta, joka on käynnistynyt Varkaudessa tämän vuoden maaliskuussa. Potentiaalisimpien siirtymätalousmaiden valintakriteereinä on käytetty aiempia tutkimuksia ja raportteja. Huomio keskitetään kiinteän biopolttoaineen resursseihin ja biopolttoaineisiin pohjautuvalle energiantuotannolle asetettuihin tavoitteisiin. Edellä mainittujen kriteerien pohjalta tarkasteltaviksi valittujen valtioiden osalta tehtiin tarkemmat kilpailukykyanalyysit, otettiin yhteyttä markkina-alueeltaalan ammattilaisiin ja kartoitettiin potentiaalisimmat markkinakohteet. Tavoitteena on arvioida varteenotettavin kilpailija kiinteisiin biopolttoaineisiin pohjautuvalle sähkön ja lämmön yhteistuotannolle, jonka perusteella laaditaan mallivoimalaitoksen kilpailukykyisen hinnan määrittämiseksi tiettyyn takaisinmaksuaikaan ja korkotekijään perustuen. Lopulta tehdään maakohtaisesti yhteenveto merkittävimmistä markkinapotentiaaliin vaikuttavista kilpailutekijöistä, arvioidaan potentiaalisin kohdemaa sekä esitetään mahdollinen investoinnin rahoitusvaihtoehto ja keinoja markkinoida tuotetta potentiaalisille asiakkaille.

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Globaalin talouden rakenteet muuttuvat jatkuvasti. Yritykset toimivat kansainvälisillä markkinoilla aiempaa enemmän. Tuotannon lisäämiseksi monet yritykset ovat ulkoistaneet tuotteidensa tuki- ja ylläpitotoiminnot halvan työvoiman maihin. Yritykset voivat tällöin keskittää toimintansa ydinosamiseensa. Vapautuneita resursseja voidaan käyttää yrityksen sisäisessä tuotekehityksessä ja panostaa seuraavan sukupolven tuotteiden ja teknologioiden kehittämiseen. Diplomityö esittelee Globaalisti hajautetun toimitusmallin Internet-palveluntarjoajalle jossa tuotteiden tuki- ja ylläpito on ulkoistettu Intiaan. Teoriaosassa esitellään erilaisia toimitusmalleja ja keskitytään erityisesti hajautettuun toimitusmalliin. Tämän lisäksi luetellaan valintakriteerejä joilla voidaan arvioida projektin soveltuvuutta ulkoistettavaksi sekä esitellään mahdollisuuksia ja uhkia jotka sisältyvät globaaliin ulkoistusprosessiin. Käytäntöosassa esitellään globaali palvelun toimittamisprosessi joka on kehitetty Internet-palveluntarjoajan tarpeisiin.

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In distributed energy production, permanent magnet synchronous generators (PMSG) are often connected to the grid via frequency converters, such as voltage source line converters. The price of the converter may constitute a large part of the costs of a generating set. Some of the permanent magnet synchronous generators with converters and traditional separately excited synchronous generators couldbe replaced by direct-on-line (DOL) non-controlled PMSGs. Small directly networkconnected generators are likely to have large markets in the area of distributed electric energy generation. Typical prime movers could be windmills, watermills and internal combustion engines. DOL PMSGs could also be applied in island networks, such as ships and oil platforms. Also various back-up power generating systems could be carried out with DOL PMSGs. The benefits would be a lower priceof the generating set and the robustness and easy use of the system. The performance of DOL PMSGs is analyzed. The electricity distribution companies have regulations that constrain the design of the generators being connected to the grid. The general guidelines and recommendations are applied in the analysis. By analyzing the results produced by the simulation model for the permanent magnet machine, the guidelines for efficient damper winding parameters for DOL PMSGs are presented. The simulation model is used to simulate grid connections and load transients. The damper winding parameters are calculated by the finite element method (FEM) and determined from experimental measurements. Three-dimensional finite element analysis (3D FEA) is carried out. The results from the simulation model and 3D FEA are compared with practical measurements from two prototype axial flux permanent magnet generators provided with damper windings. The dimensioning of the damper winding parameters is case specific. The damper winding should be dimensioned based on the moment of inertia of the generating set. It is shown that the damper winding has optimal values to reach synchronous operation in the shortest period of time after transient operation. With optimal dimensioning, interferenceon the grid is minimized.

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The research of power-line communications has been concentrated on home automation, broadband indoor communications and broadband data transfer in a low voltage distribution network between home andtransformer station. There has not been carried out much research work that is focused on the high frequency characteristics of industrial low voltage distribution networks. The industrial low voltage distribution network may be utilised as a communication channel to data transfer required by the on-line condition monitoring of electric motors. The advantage of using power-line data transfer is that it does not require the installing of new cables. In the first part of this work, the characteristics of industrial low voltage distribution network components and the pilot distribution network are measured and modelled with respect topower-line communications frequencies up to 30 MHz. The distributed inductances, capacitances and attenuation of MCMK type low voltage power cables are measured in the frequency band 100 kHz - 30 MHz and an attenuation formula for the cables is formed based on the measurements. The input impedances of electric motors (15-250 kW) are measured using several signal couplings and measurement based input impedance model for electric motor with a slotted stator is formed. The model is designed for the frequency band 10 kHz - 30 MHz. Next, the effect of DC (direct current) voltage link inverter on power line data transfer is briefly analysed. Finally, a pilot distribution network is formed and signal attenuation in communication channels in the pilot environment is measured. The results are compared with the simulations that are carried out utilising the developed models and measured parameters for cables and motors. In the second part of this work, a narrowband power-line data transfer system is developed for the data transfer ofon-line condition monitoring of electric motors. It is developed using standardintegrated circuits. The system is tested in the pilot environment and the applicability of the system for the data transfer required by the on-line condition monitoring of electric motors is analysed.

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Technological development brings more and more complex systems to the consumer markets. The time required for bringing a new product to market is crucial for the competitive edge of a company. Simulation is used as a tool to model these products and their operation before actual live systems are built. The complexity of these systems can easily require large amounts of memory and computing power. Distributed simulation can be used to meet these demands. Distributed simulation has its problems. Diworse, a distributed simulation environment, was used in this study to analyze the different factors that affect the time required for the simulation of a system. Examples of these factors are the simulation algorithm, communication protocols, partitioning of the problem, distributionof the problem, capabilities of the computing and communications equipment and the external load. Offices offer vast amounts of unused capabilities in the formof idle workstations. The use of this computing power for distributed simulation requires the simulation to adapt to a changing load situation. This requires all or part of the simulation work to be removed from a workstation when the owner wishes to use the workstation again. If load balancing is not performed, the simulation suffers from the workstation's reduced performance, which also hampers the owner's work. Operation of load balancing in Diworse is studied and it is shown to perform better than no load balancing, as well as which different approaches for load balancing are discussed.

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Tässä työssä on selvitetty sellutehtaan höyryverkosta tehtaan ulkopuolelle myytävän ylijäämähöyryn määrän ja paineen nopeaan vaihteluun vaikuttavia tekijöitä. Työssä on tarkasteltu höyryn kehityksen ja kulutuksen vaihtelun vaikutusta ylijäämähöyryyn. Lisäksi on tarkasteltu mahdollisuuksia edellä mainittujen häiriöiden tasaamiseksi. Työssä on selvitetty teoriaa, joka vaikuttaa sellutehtaan höyryn kehitykseen ja kulutukseen. Lisäksi on selvitetty energiataselaskennan ja höyryverkon hallintaa parantavien toimenpiteiden teoriaa. Omana kokonaisuutena on sellutehtaan höyryn kehityksen ja kulutuksen tarkastelu sekä selvitys tehtaan höyryverkon hallinnan nykytilasta. Höyryverkolle on muodostettu energiatase. Työn tuloksia varten on kerätty ja tallennettu mittapistetietoa tiedonkeräysjärjestelmän avulla eri höyryverkon mittapisteistä. Työn tuloksina on mainittu useita höyryverkon hallintaa parantavia toteutuskelpoisia asioita ja toimenpiteitä. Työllä on luotu pohjaa menetelmälle, joka ohjaa energian kehitystä vastaamaan sellun tuotannon tarvitsemaa energiamäärää. Samalla saataisiin paremmin hallittua ylijäämähöyryä ja sen määrän sekä paineen vaihtelu vähentyisi.

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Tässä diplomityössä on oletettu että neljännen sukupolven mobiiliverkko on saumaton yhdistelmä olemassa olevia toisen ja kolmannen sukupolven langattomia verkkoja sekä lyhyen kantaman WLAN- ja Bluetooth-radiotekniikoita. Näiden tekniikoiden on myös oletettu olevan niin yhteensopivia ettei käyttäjä havaitse saanti verkon muuttumista. Työ esittelee neljännen sukupolven mobiiliverkkoihin liittyvien tärkeimpien langattomien tekniikoiden arkkitehtuurin ja perustoiminta-periaatteet. Työ kuvaa eri tekniikoita ja käytäntöjä tiedon mittaamiseen ja keräämiseen. Saatuja transaktiomittauksia voidaan käyttää tarjottaessa erilaistettuja palvelutasoja sekä verkko- ja palvelukapasiteetin optimoimisessa. Lisäksi työssä esitellään Internet Business Information Manager joka on ohjelmistokehys hajautetun tiedon keräämiseen. Sen keräämää mittaustietoa voidaan käyttää palvelun tason seurannassa j a raportoinnissa sekä laskutuksessa. Työn käytännön osuudessa piti kehittää langattoman verkon liikennettä seuraava agentti joka tarkkailisi palvelun laatua. Agentti sijaitsisi matkapuhelimessa mitaten verkon liikennettä. Agenttia ei kuitenkaan voitu toteuttaa koska ohjelmistoympäristö todettiin vajaaksi. Joka tapauksessa työ osoitti että käyttäjän näkökulmasta tietoa kerääville agenteille on todellinen tarve.

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The economical competitiveness of various power plant alternatives is compared. The comparison comprises merely electricity producing power plants. Combined heat and power (CHP) producing power will cover part of the future power deficit in Finland, but also condensing power plants for base load production will be needed. The following types of power plants are studied: nuclear power plant, combined cycle gas turbine plant, coal-fired condensing power plant, peat-fired condensing power plant, wood-fired condensing power plant and wind power plant. The calculations are carried out by using the annuity method with a real interest rate of 5 % per annum and with a fixed price level as of January 2008. With the annual peak load utilization time of 8000 hours (corresponding to a load factor of 91,3 %) the production costs would be for nuclear electricity 35,0 €/MWh, for gas based electricity 59,2 €/MWh and for coal based electricity 64,4 €/MWh, when using a price of 23 €/tonCO2 for the carbon dioxide emission trading. Without emission trading the production cost of gas electricity is 51,2 €/MWh and that of coal electricity 45,7 €/MWh and nuclear remains the same (35,0 €/MWh) In order to study the impact of changes in the input data, a sensitivity analysis has been carried out. It reveals that the advantage of the nuclear power is quite clear. E.g. the nuclear electricity is rather insensitive to the changes of nuclear fuel price, whereas for natural gas alternative the rising trend of gas price causes the greatest risk. Furthermore, increase of emission trading price improves the competitiveness of the nuclear alternative. The competitiveness and payback of the nuclear power investment is studied also as such by using various electricity market prices for determining the revenues generated by the investment. The profitability of the investment is excellent, if the market price of electricity is 50 €/MWh or more.

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Uusiutuvan energian tuottamisen lisääminen on edellytys saavuttaaksemme EU:n asettamat tavoitteet. Tämän takia on syytä tutkia kaikki mahdollisuudet uusiutuvan energian tuottamisen lisäämiseksi jopa aivan pienimmistä laitoksista lähtien. Tämän työn tarkoituksena on tutkia pienvesivoiman taloudellisuutta ja kannattavuutta energiantuotannossa. Työssä suoritetaan myös kustannuslaskenta, jossa pohditaan käytöstä poistetun laitoksen palauttamista takaisin sähkön tuotantoon. Samalla käydään läpi teknisiä, taloudellisia ja lakisääteisiä kysymyksiä, joita pienvoiman verkkoonliittäminen aiheuttaa. Tämä työ on eräänlainen käsikirja pienvesivoimasta. Pienvesivoiman liittäminen jakeluverkkoon on sinällään suojausteknisesti yksinkertaista, mutta kaikkien eri taloudellisten ja lakiteknisten tekijöiden huomioonottaminen on puolestaan haastavaa. Laitosten käyttö ja kunnossapito eivät sinällään vaadi sähköteknistä osaamista, kunhan turvallisuusseikat otetaan visusti huomioon. Työssä havaittiin, että pienvesivoima ei pienissä laitoksissa riitä kattamaan suuria työvoimakustannuksia, joita syntyy, kun yritysten henkilökunta ottaa osaa laitoksen toimintaan. Toisaalta pienvesivoima on erinomainen tapa tuottaa sähköä yksityiselle ihmiselle, mikäli hän on itse valmis operoimaan laitosta eikä laske omalle työlleen suuria kustannuksia. Edellytyksenä on, että omalta maa‐alueelta löytyy pienikin puro suhteellisen läheltä jakeluverkkoa.