Tampere University of Technology

About: Tampere University of Technology is a based out in . It is known for research contribution in the topics: Laser & Context (language use). The organization has 6802 authors who have published 19787 publications receiving 431793 citations. The organization is also known as: Tampereen teknillinen yliopisto.

Results from the CERN pilot CLOUD experiment

Abstract: . During a 4-week run in October–November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the Cosmics Leaving OUtdoor Droplets (CLOUD) experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm−3s−1, and growth rates between 2 and 37 nm h−1. The corresponding H2O concentrations were typically around 106 cm−3 or less. The experimentally-measured formation rates and H2SO4 concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most important lessons for the CLOUD design include the stringent requirement of internal cleanliness of the aerosol chamber, as well as maintenance of extremely stable temperatures (variations below 0.1 °C

EEG/MEG source imaging: methods, challenges, and open issues

Abstract: We present the four key areas of research--preprocessing, the volume conductor, the forward problem, and the inverse problem-- that affect the performance of EEG and MEG source imaging. In each key area we identify prominent approaches and methodologies that have open issues warranting further investigation within the community, challenges associated with certain techniques, and algorithms necessitating clarification of their implications. More than providing definitive answers we aim to identify important open issues in the quest of source localization.

Generation of metal and metal oxide nanoparticles by liquid flame spray process

Abstract: A liquid flame spray (LFS) process has been investigated for the generation of single component nanoparticles. In the LFS process, a solution consisting of metal nitrate dissolved in water is sprayed into a turbulent, high temperature H2-O2-flame. The primary spray droplets evaporate and subsequent reactions in the flame produce metal or metal oxide vapours which nucleate to final particulate form. In the study, the process characteristics were examined to produce 10–60 nm particles from silver, palladium and iron containing precursors. A systematic study using variable process parameters proved that the size of the generated nanoparticles is set by the mass flow rate of the metal precursor, only. The geometric standard deviation of the size distributions was seen to vary in a limited range of 1.35–1.4. The particle size was verified by aerosol instrumentation, the composition and morphology by X-ray diffraction (XRD) and transmission electron microscopy (TEM), correspondingly. The Ag and Pd particles were seen to consist of pure metals. For iron, the presence of all three of the following compounds were detected: Fe, Fe2O3 and Fe3O4.

Modulation control and spectral shaping of optical fiber supercontinuum generation in the picosecond regime

Abstract: Numerical simulations are used to study how fiber supercontinuum generation seeded by picosecond pulses can be actively controlled through the use of input pulse modulation. By carrying out multiple simulations in the presence of noise, we show how tailored supercontinuum Spectra with increased bandwidth and improved stability can be generated using an input envelope modulation of appropriate frequency and depth. The results are discussed in terms of the non-linear propagation dynamics and pump depletion.

Strong Strain Sensing Performance of Natural Rubber Nanocomposites.

Abstract: A detail study concerning the strain (tensile) dependent electrical conductivity of elastomeric composites is reported in this present paper. Multiwall carbon nanotubes (CNT), conducting carbon black (CB), and their combinations were considered as conducting filler in cross-linked natural rubber matrix. The loadings of the fillers were considered from 3 to 11 phr (filler concentration close to their percolation threshold). Without hindering the elastic nature of the composite (reversible stretchability up to several 100%), the change of relative resistance, ΔR/R0 (ΔR is the change in the resistance with respect to strain and R0 is the initial resistance of the sample) of the CB filled composites was found to be as much as ∼1300 at around 120% elongation. This value is much higher than any other reported values obtained from conducting polymeric composites. It was found that CNT offered a strong strain dependent character in the regime 100% to 150% elongation, whereas, the carbon black filled natural rubbe...