Tutkimuksesta ideoita ja innovaatioita - Lukella tuhannen taalan paikka

Kolumni julkaistu alunperin metla.fi sivustolla, Luken NEW-ohjelma201

Biting the dirty hand that feeds you Relations and Resistance in the Bidi Bidi refugee camp, Northern Uganda

MasteroppgaveSANT350MASV-SAN

Amputation following internal fixation of an ankle fracture via the posterolateral approach - a case report

Peer reviewe

Microalgae-utilizing biorefinery concept for pulp and paper industry: Converting secondary streams into value-added products

Traditional pulp and paper industry is in transition due to increased competition and changes in consumption habits. Advanced biorefining is seen as one option to create new business opportunities. This article presents a microalgae-utilizing biorefinery which is integrated into a traditional pulp and paper mill and which produces high-value algal products, fertilizer and biogas from secondary process streams. Presented biorefinery process is validated with mass balances, employing initial data from a Scandinavian pulp and paper mill. Results indicate that the proposed process is technically viable. Production potential is sensitive to light and nutrient availability in algae cultivation, and seasonal changes in irradiance result in significant output variation. The biorefinery process can be generalized to other process industry and wastewater treatment plants that have similar output flows.Peer reviewe

Coordinated Dynamic Spectrum Sharing Between Terrestrial and Non-Terrestrial Networks in 5G and Beyond

The emerging Non-Terrestrial Networks (NTNs) can aid to provide 5G and beyond services everywhere and anytime. However, the vast emergence of NTN systems will introduce an unseen interference to both the existing satellite systems and Terrestrial Networks (TNs). For that, there is a need for novel ideas on how to efficiently utilize the co-existing systems with the ever-increasing competition on scarce spectrum resources. Dynamic Spectrum Sharing (DSS) is a promising technique in which different systems can operate on the same spectrum, thus increasing the spectrum efficiency and offering better coverage for the users. In this paper, we present a centralized scheme for achieving coordinated DSS to protect the primary TN while providing NTN with sufficient resources. The scheme is evaluated by system simulations in a scenario with a TN and low earth orbit satellite. The results reveal that in a low traffic demand situation, the primary TN users are not affected negatively while the NTN can provide service to the rural area. In high-demand traffic situations, the peak performance of the TN inevitably suffers but the TN cell edge and NTN users' performance is improved.Comment: 2023 IEEE 24th International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM

On scattering behavior of corner domains with anisotropic inhomogeneities

This paper investigates the possible scattering and non-scattering behavior of an anisotropic and inhomogeneous Lipschitz medium at a fixed wave number and with a single incident field. We connect the anisotropic non-scattering problem to a Bernoulli type free boundary problem. By invoking methods from the theory of free boundaries, we show that an anisotropic medium with Lipschitz but not $C^{1,\alpha}$ boundary scatters every incident wave that satisfies a non-degeneracy condition.Comment: 20 page

On positivity sets for Helmholtz solutions

We address the question of finding global solutions of the Helmholtz equation that are positive in a given set. This question arises in inverse scattering for penetrable obstacles. In particular, we show that there are solutions that are positive on the boundary of a bounded Lipschitz domain.Comment: 10 page

On Enhancing Reliability in B5G NTNs with Packet Duplication via Multi-Connectivity

Non-Terrestrial Networks (NTNs) can be used to provide ubiquitous 5G and beyond services to un(der)served areas. To ensure reliable communication in such networks, packet duplication (PD) through multi-connectivity is a promising solution. However, the existing PD schemes developed for terrestrial environments may not be reactive enough for the NTN environment where propagation delays are significantly longer. This paper proposes a dynamic PD activation scheme for NTNs based on hybrid automatic repeat request feedback. The scheme aims to reduce the number of duplicated packets while maintaining high reliability. To evaluate the proposed scheme, simulations are conducted in a scenario with two transparent payload lowearth orbit satellites. The results show a significant reduction of 87.2% in the number of duplicated packets compared to blind duplication, with only marginal compromise in reliability.Comment: Accepted for publication in 2023 IEEE International Conference on Wireless for Space and Extreme Environments (WiSEE 2023

Introduction to Lagrangian and Hamiltonian mechanics

Suomalaisissa teknillisissä yliopistoissa differentiaaligeometrian opetus on suhteellisen vähäistä, ellei suorastaan olematonta. Se totuus, että differentiaaligeometrian merkittävimpiä käytännön sovelluksia on yleinen suhteellisuusteoria, antaa suuntaviittaa siitä, että kyseisellä matematiikan osa-alueella voi olla jotain tekemistä nykypäivän modernin teknillisen fysiikan kanssa. Differentiaaligeometria on kieli, jolla fysiikan teoriat voidaan pukea matemaattisesti yleispätevään muotoon. Jos fysiikan ilmiötä ei voida pukea tälle kielelle, on se oire siitä, että ilmiötä ei ymmärretä tarpeeksi hyvin. Tällä diplomityöllä on kolme tavoitetta. Ensimmäinen on tarjota työkalut tämän edellä mainitun kielen ymmärtämiseen. Toisena tavoitteena on esitellä fysikaalisen luonnon matemaattinen rakenne kerros kerrokselta, differentiaaligeometrian kieltä hyväksi käyttäen. Kolmas on soveltaa opittuja työkaluja klassisen mekaniikan teorioihin. Newtonilaista mekaniikkaa pidetään klassisen mekaniikan synonyymina, mutta on olemassa myös kaksi muuta mekaniikan muotoilua, jotka ovat newtonilaista lähestymistapaa perustavanlaatuisempia. Nämä ovat nimeltään Lagrangen ja Hamiltonin mekaniikat, joita kutsutaan myös mekaniikan pääformalismeiksi. Jotta näitä kahta mekaniikan lähestymistapaa voitaisiin ymmärtää syvällisesti, on niitä tarkasteltava geometrisesti. Varsinkin haastavimmissa mekaniikan sovelluksissa Lagrangen ja Hamiltonin lähestymistavat ovat välttämättömyyksiä. Differentiaaligeometrian läheinen tuntemus antaa syvempää näkökulmaa fysikaalisten ilmiöiden ymmärtämiseen. Tämä diplomityö voisi toimia aiheesta kiinnostuneen yliopisto-opiskelijan ensimmäisenä differentiaaligeometrian teoksena