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Tiivistelmä. Persistence of Vision (POV) on ihmissilmään liittyvä konsepti, jonka mukaan ihminen näkee kaikkialla jälkikuvia. Ikään kuin kaikki nähtäisiin pitkällä valotusajalla otettuina kuvina. Tähän ilmiöön liittyen on keksitty tehdä nopeasti pyöriviä LED-POV-näyttöjä, joissa yksi rivi LED-valoja pyörii tasossa niin nopeaa, että niillä voidaan muodostaa selviä kuvia. Tässä työssä tehtiin samaan ideaan pohjautuen osoitin puhaltimesta. Puhaltimen siipeen on piirretty valkoinen viiva, jota väläytetään LED-valolla. Puhaltimen takometrista saadaan sisääntulosignaali, josta koodataan signaali LED:n väläyttämiseksi. Työssä käytettiin Arduino Uno -mikrokontrolleria. Arduinolle kirjoitettiin koodi, jolla osoitin saatiin näkymään joka kierros halutussa kulmassa. Kulma annettiin näppäimistöllä sarjaportin kautta. POV-näyttö koottiin koekytkentälevylle ja sen kierrosaika oli noin 11 ms, joka vastaa 90 Hz virkistystaajuutta.POV-display with a fan. Abstract. Persistence of Vision (POV) is a concept regarding a human eye which states that human eye sees afterimages all the time, as if we see everything as long exposure time photographs. This phenomenon has been used to make rapidly rotating platforms which create clear images with just a single row of LEDs. Based on POV phenomenon a pointer was made of a fan in this thesis. A white stripe is drawn on a propeller of a fan and it is flashed with a LED. The fan has a built-in tachometer which is used as a position encoder. A code was written to Arduino Uno microcontroller for timing the flashing of the LED. The angle where the stripe is seen is given with a keyboard through Arduino’s serial port. The POV-screen was assembled on a breadboard and its time per revolution was 11 ms which means 90 Hz refresh rate.

In this work we have studied AuSn and CuSn Solid-Liquid Interdiffusion (SLID) bonding that can be used for wafer-level encapsulation. SLID bonding of these metal structures takes place at temperatures around 300°C but show higher re-melting temperatures because of the solid-liquid intermetallic phase transformation. 6'' silicon wafers were bonded with 60 ??m wide, electroplated, AuSn and CuSn seal ring structures. Wafer bonding temperature was varied between 300°C and 450°C, the used bonding force was 3.5 kN under the ambient pressure less than 1x10-3 mbar. The bonding quality was evaluated with different seal ring metal structures and bonding parameters

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In MEMS industry, silicon-on-insulator (SOI) wafers are gaining ground from blank silicon wafers as the main starting substrate. Tailored SOI wafers available in the market contain for example buried cavities or a buried gettering layer. Adding another layer in addition to the thermal SiO2 insulator, or replacing it with another material altogether, could be a way to tailor the properties of SOI wafers further. In this work, the direct wafer bonding of ALD TiO2, and Al2O3 for reference, is investigated, eventually in order to fabricate SOI wafers with other buried ALD oxides.

Atomic layer deposition (ALD) is currently a widespread method to grow conformal thin films with a sub-nm thickness control. By using ALD for nanolaminate oxides, it is possible to fine tune the electrical, optical and mechanical properties of thin films. In this study the elemental depth profiles and surface roughnesses were determined for Al2O3 + TiO2 nanolaminates with nominal single-layer thicknesses of 1, 2, 5, 10 and 20 nm and total thickness between 40 nm and 60 nm. The depth profiles were measured by means of a time-of-flight elastic recoil detection analysis (ToF-ERDA) spectrometer recently installed at the University of Jyväskylä. In TOF-E measurements 63Cu, 35Cl, 12C and 4He ions with energies ranging from 0.5 to 10 MeV, were used and depth profiles of the whole nanolaminate film could be analyzed down to 5 nm individual layer thickness. peerReviewed

Biogenic aerosol formation is likely to contribute significantly to the global aerosol load. In recent years, new-particle formation (NPF) has been observed in various ecosystems around the world but hardly any measurements have taken place in the terrestrial Southern Hemisphere. Here, we report the first results of atmospheric ion and charged particle concentrations as well as of NPF in a Eucalypt forest in Tumbarumba, South-East Australia, from July 2005 to October 2006. The measurements were carried out with an Air Ion Spectrometer (AIS) with a size range from 0.34 to 40 nm. Daytime aerosol formation took place on 52% of days with acceptable data. Median growth rates (GR) for negative/positive 1.3–3 nm particles were 2.29/2.02 nmh−1; for 3–7 nm particles 3.04/2.94 nmh−1; and for 7–20 nm particles 7.13/5.62 nmh−1, respectively. Intermediate ion growth rates were highest when the wind was blowing from the direction of the native Eucalypt forest, suggesting that the Eucalypts were the strongest source of condensable vapours. Average cluster ion (0.34 to 1.8 nm) concentrations were very high, 2400/1700 cm−3 for negative/positive ions compared to other measurements around the world. These high concentrations are probably the result of the strong radon efflux from the soils around the Tumbarumba field site. Furthermore, comparison between nighttime and daytime concentrations supported the view that cluster ions are produced close to the surface within the boundary layer also at night but that large ions are mostly produced in daytime. Finally, a previously unreported phenomenon, nocturnal aerosol formation, appeared on 32% of the analysed nights but was clustered almost entirely within six months from summer to autumn in 2006. From January to May, nocturnal formation was 2.5 times as frequent as daytime formation. Therefore, it appears that in summer and autumn, nocturnal production was the major mechanism for aerosol formation in Tumbarumba.

International audience

International audience; The possible connections between the carbon balance of ecosystems and aerosol-cloud-climate interactions play a significant role in climate change studies. Carbon dioxide is a greenhouse gas, whereas the net effect of atmospheric aerosols is to cool the climate. Here, we investigated the connection between forest-atmosphere carbon exchange and aerosol dynamics in the continental boundary layer by means of multiannual data sets of particle formation and growth rates, of CO2 fluxes, and of monoterpene concentrations in a Scots pine forest in southern Finland. We suggest a new, interesting link and a potentially important feedback among forest ecosystem functioning, aerosols, and climate: Considering that globally increasing temperatures and CO2 fertilization are likely to lead to increased photosynthesis and forest growth, an increase in forest biomass would increase emissions of non-methane biogenic volatile organic compounds and thereby enhance organic aerosol production. This feedback mechanism couples the climate effect of CO2 with that of aerosols in a novel way.