Discontinuous gradient constraints and the infinity Laplacian

Motivated by tug-of-war games and asymptotic analysis of certain variational problems, we consider a gradient constraint problem involving the infinity Laplace operator. We prove that this problem always has a solution that is unique if a certain regularity condition on the constraint is satisfied. If this regularity condition fails, then solutions obtained from game theory and $L^p$-approximation need not coincide

Improved stability of black silicon detectors using aluminum oxide surface passivation

Publisher Copyright: © 2021 ESA and CNESWe have studied how high-energy electron irradiation (12 MeV, total dose 66 krad(Si)) and long term humidity exposure (75%, 75 °C, 500 hours) influence the induced junction black silicon or planar photodiode characteristics. In our case, the induced junction is formed using n-type silicon and atomic-layer deposited aluminum oxide (Al2O3), which contains a large negative fixed charge. We compare the results with corresponding planar pn-junction detectors passivated with either with silicon dioxide (SiO2) or Al2O3. The results show that the induced junction detectors remain stable as their responsivity remains nearly unaffected during the electron beam irradiation. On the other hand, the SiO2 passivated counterparts that included conventional pn-junction degrade heavily, which is seen as strongly reduced UV response. Similarly, after humidity test the response of the induced junction detector remains unaffected, while the pn-junction detectors passivated with SiO2 degrade significantly, for instance, the response at 200 nm reduces to 50% from the original value. Interestingly, the pn-junction detectors passivated with Al2O3 exhibit no degradation of UV response, indicating that the surface passivation properties of Al2O3 are more stable than SiO2 under the studied conditions. This phenomenon is further confirmed with PC1D simulations suggesting that the UV degradation results from increased surface recombination velocity. To conclude, the results presented here suggest that black silicon photodiodes containing Al2O3-based induced junction are highly promising alternatives for applications that require the best performance and long-term stability under ionizing and humid conditions.Peer reviewe

Donate Speech : Collecting and Sharing a Large-Scale Speech Database for Social Sciences, Humanities and Artificial Intelligence Research and Innovation

The Donate Speech campaign aimed to collect 10 000 hours of ordinary, casual Finnish speech to be used for studying language as well as for developing technology and services that can be readily used in the languages spoken in Finland. In this project, particular attention has been paid to allowing for both academic and commercial use of the material. Even though the ambitious target currently seems to evade us, the Donate Speech campaign has managed to collect an extensive resource of more than 3500 h of Finnish colloquial speech with more than 200 000 speech recordings by roughly 50 000 speakers from all over Finland in just a few months.Peer reviewe

Evidence for universality of tunable-barrier electron pumps

We review recent precision measurements on semiconductor tunable-barrier electron pumps operating in a ratchet mode. Seven studies on five different designs of pumps have reported measurements of the pump current with relative total uncertainties around 10-6 or less. Combined with theoretical models of electron capture by the pumps, these experimental data exhibits encouraging evidence that the pumps operate according to a universal mechanism, independent of the details of device design. Evidence for robustness of the pump current against changes in the control parameters is at a more preliminary stage, but also encouraging, with two studies reporting robustness of the pump current against three or more parameters in the range of ∼5 × 10-7 to ∼2 × 10-6. This review highlights the need for an agreed protocol for tuning the electron pump for optimal operation, as well as more rigorous evaluations of the robustness in a wide range of pump designs

Lahjoita puhetta Kielipankkiin tekoälyn kehittämistä varten

Det behövs tusentals timmar med vardagsprat för forskning och innovation i samhällsvetenskap, humaniora och artificiell intelligens. För att utveckla nättjänster som förstår svenska och finska i Finland har Språkbanken i Finland tillsammans med Yle, det nationella public service-bolaget för radio, tv och webb, samlat in 4 000 timmar vardagsfinska via nätet. Insamlingen genomfördes med understöd från statens utvecklingsbolag Vake. En insamling av vardagsprat på finlandssvenska är på gång i samarbete med Svenska litteratursällskapet i Finland, och målet är ett liknande projekt även för samiska i Norden.Non peer reviewe