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Kuopio, Finland

Sarkka S.,Aalto University | Hartikainen J.,Rocsole Ltd
IEEE International Workshop on Machine Learning for Signal Processing, MLSP | Year: 2013

We consider joint estimation of state and time-varying noise covariance matrices in non-linear stochastic state space models. We propose a variational Bayes and Gaussian non-linear filtering based algorithm for efficient computation of the approximate filtering posterior distributions. The formulation allows the use of efficient Gaussian integration methods such as unscented transform, cubature integration and Gauss-Hermite integration along with the classical Taylor series approximations. The performance of the algorithm is illustrated in a simulated application. © 2013 IEEE. Source

Rahomaki J.,University of Eastern Finland | Hyvarinen H.J.,Rocsole Ltd | Rehman S.,National University of Singapore | Rehman S.,Singapore MIT Alliance for Research and Technology | Turunen J.,University of Eastern Finland
Nanoscale Research Letters | Year: 2013

We propose a scheme based on extraordinary transmission of light through a single nanoaperture, surrounded by periodic corrugations, for direct characterization of focal-region optical fields with subwavelength-scale structure. We describe the design of the device on the basis of rigorous diffraction theory and fabricate a prototype using a process that involves electron beam lithography, dry etching, and template stripping. First experimental results performed with a transmission-type confocal optical microscope demonstrate the potential of the method. © 2013 Rahomäki et al. Source

Oravisjarvi K.,University of Oulu | Pietikainen M.,University of Oulu | Ruuskanen J.,University of Eastern Finland | Niemi S.,University of Vaasa | And 6 more authors.
Journal of Aerosol Science | Year: 2014

Regional deposition of diesel particles in the human lungs was analyzed and the chemical composition of inhaled particles was investigated. The off-road diesel engine with a diesel particulate filter (DPF) or a selective catalytic reduction (SCR) unit and without any exhaust after-treatment system was used. Around 85-95% of the measured particles were of ultrafine size and 53-84% of those nanoparticles. Over 70% of the deposited particles under 0.1. μm and about 45-70% of the deposited particles from 0.1 to 1. μm reach also the alveolar-interstitial level. Elements analyzed in particles were C, O, Fe, Si, Ti, Na, K, Ca, Mg, Ba, Mn, Zn, Cu, Cl, P, S and N. The proportion of PAHs in the measured particle mass was 0.05% and carcinogenic ones represented 1.3% of the total PAHs. The DPF system removed particles efficiently and up to 99% of the particles were removed. The total number of particles deposited in the lungs was generally lower when DPF was used compared to other setups. These particles contained though the largest variety of elements, which are commonly considered harmful to humans. Therefore it is difficult to conclude, whether exhaust particles from a diesel engine with a DPF unit would be less harmful to human health. © 2013. Source

A method for determining the location of an interface of interest in a target domain, between a free volume of a flowable material and a solid material limiting said free volume, the method involves the steps of providing a mathematical model of the target domain determining, for a plurality of pairs of electrode groups, a characteristic electrical quantity proportional to the capacitance of a capacitor formed by a pair of electrode groups; receiving measurements of the characteristic electrical quantity for a plurality of pairs of electrode groups; adjusting the mathematical model by varying the location of the boundary surface in order to take into account possible wear of the boundary surface so as to reduce the differences between the measured characteristic electrical quantities and those defined by the mathematical model; and determining the location of the interface of interest on the basis of the adjusted mathematical model.

A method for investigating permittivity within a target domain comprises a step of measuring, for a plurality of pairs of contact element groups, the contact elements of the contact element groups being arranged in capacitance measurement connection with the target domain, an electrical quantity of interest proportional to the capacitance of a capacitor formed by a pair of contact element groups; the contact elements comprising a plurality of electrodes supported between the target domain and an electrically conductive background body limiting the capacitance measurement zone of the electrodes. The contact elements may further comprise the electrically conductive background body.

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