Search results for "wave"
showing 10 items of 6009 documents
A New Solution for Sea Wave Energy Harvesting, the Proposal of an Ironless Linear Generator
2020
The paper investigates an innovative ironless linear generator, installable inside a wave energy converter, in order to produce electricity from sea waves. This energy source is considered strategic for the future, especially in small islands
Topological surface wave metamaterials for robust vibration attenuation and energy harvesting
2021
International audience; We propose topological metamaterials working in Hertz frequency range, constituted of concrete pillars on the soil ground in a honeycomb lattice. Based on the analog of the quantum valley Hall effect, a non-trivial bandgap is formed by breaking the inversion symmetry of the unit cell. A topological interface is created between two different crystal phases whose robustness against various defects and disorders is quantitatively analyzed. Finally, we take advantage of the robust and compact topological edge state for designing a harvesting energy device. The results demonstrate the functionality of the proposed structure for both robust surface vibration reduction and …
Microwave-Assisted Esterification of Tall Oil Fatty Acids with Methanol Using Lignin-Based Solid Catalyst
2016
During alkaline pulping significant amounts of lignin, carbohydrates (mostly hemicelluloses), and extractives (tall oil soap and turpentine) are removed from wood feedstock. In this study, the catalytic esterification of fatty acids in tall oil with methanol to produce fatty acid methyl esters under microwave irradiation was performed at 100 °C for 10–60 min. A novel heterogeneous acid catalyst tested for this purpose was synthesized from the hardwood alkali lignin that was precipitated by acidification from the black liquor from soda-AQ pulping. The comparative reaction data were obtained by using other solid catalysts, Amberlyst 15, and p-toluenesulfonic acid. The results showed the highe…
The role of evanescent modes in Global-Local analysis of UGW in plates with varying local zone-scatterer relations
2023
In order to provide a reliable and robust SHM performance, Ultrasonic Guided Waves (UGWs) need to be analyzed and understood. Numerical modeling of UGW propagation and scattering by hybrid methods offers the possibility of simulating UGW interaction with waveguides of arbitrary cross-sections and discontinuities. Maximizing the accuracy of such methods is important to perform quantitative SHM, while maintaining minimum computational cost. This work investigates the role of evanescent modes in the numerical analysis of UGWs in aluminum and composite plates with defects, by the hybrid Global-Local method. The complex solutions to the UGW eigenvalue problem are found and the scattering spectra…
Optimisation of Conditions for Extraction of Biologically Active Compounds from Common Bryophytes in Latvia / Latvijâ Augoðu Briofîtu Ekstrakcijas Ap…
2015
Abstract Bryophytes are the second largest taxonomic group in the plant kingdom. They contain a high number of biologically active compounds. Studies of their composition are important for understanding evolutionary processes in the plant kingdom. The aim of this study was to assess bryophyte secondary metabolite extraction options and to increase the yields of polyphenols and substances determining the free radical scavenging activity of bryophyte extracts. Similar studies have been conducted using higher plants as model organisms, but not using bryophytes. Comparison of five extraction methods (conventional, Soxhlet extraction, treatment with microwaves, ultrasound, and supercritical CO2 …
Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009
2017
Astronomy and astrophysics 603, A31 (2017). doi:10.1051/0004-6361/201629540
Cladding-Pumped Er/Yb-Co-Doped Fiber Amplifier for Multi-Channel Operation
2022
The Institute of Solid State Physics, University of Latvia, as a Center of Excellence, has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2. We express our gratitude to rer. nat. Nicoletta Haarlammert from Fraunhofer Institute for Applied Optics and Precision Engineering IOF for the refractive index measurements of ytterbium/erbium-co-doped fibers. This work is supported by the European Regional Development Fund project No. 1.1.1.1/18/A/068.
Tema starosti v romane Gajto Gazdanova "Nočnye dorogi"
2016
Do tematu starości niejednokrotnie zwracał się w swojej twórczości przedstawiciel młodszego pokolenia pierwszej fali emigracji rosyjskiej, Gajto Gazdanow, najczęściej rozpatrując starość w kontekście sensu życia i śmierci. Ważna w tym zakresie jest powieść Nocne drogi, w której temat starości i stosunek do niej zostały zrealizowane głównie w historii właścicielki kawiarni, historii prostytutki Raldi, staruszka-kierowcy itd. Wszyscy bohaterowie mają cechy indywidualne, precyzyjnie uchwycone i wyrażone przez narratora. Temat starości dla Gazdanowa to przede wszystkim możliwość rozważania o sensie życia i śmierci, pokazania kontrastu pomiędzy ograniczonością, bezsensem istnienia i przeżywaniem…
Brain Monitoring Via an Innovative CW-FNIRS System
2015
Functional Near InfraRed Spectroscopy (fNIRS) is an imaging technique mainly devoted to human brain monitoring. It is used as a non-invasive technique, in medical field, in order to measure the oxygen concentration of blood. This because the relatively good transparency of biological materials in the near infrared allows sufficient photon transmission through tissues. Within the so-called fNIRS range (650-900 nm), the main absorbers are blood chromophores, in particular the oxygenated and deoxygenated haemoglobin (HbO2 and Hb, respectively). When two or more wavelengths are used, changes of such chromophores can be computed by employing the modified Beer-Lambert law, thus providing importan…
Microstructure and characteristic properties of dogfish skin gelatin gels prepared by freeze/spray-drying methods
2020
International audience; The effects of two pretreatments (microwaves or oven-drying) on the dogfish (Squalus acanthias) skin as well as two drying processes (freeze-drying or spray-drying) on the extracted gelatins were studied. Thus six types of gelatins were obtained, three of which were freeze-dried (FG) and the others were spray-dried (SG), from the untreated skin (US), microwaves-pretreated skin (MS) and oven-pretreated skin (OS). The highest yield (8.67%) was obtained for the OSFG, while the lowest one (3.06%) was measured for the OSSG. Interestingly, all gelatins exhibited relatively high protein (84.02-89.53%), and low lipid (0.50-1.71%) and ash (3.05-7.17%) contents. In addition, g…