245 research outputs found
Synthesis of highly functional polyols from epoxidized tall oil; processing of rigid polyurethane foams and characterization of its physico-mechanical properties
No full textAugstas funkcionalitātes poliolu sintēze no epoksidētas tallu eļļas; cieto poliuretāna putuplastu iegūšana un fizikāli-mehānisko īpašību raksturošana. B.Sc. Vanags E., zinātniskie vadītāji vadošais pētnieks, Dr. Sc. Ing. Cābulis U.; Prof., Dr. Chem. Arturs Vīksna. Maģistra darbs, 87 lappuses, 34 attēli, 17 tabulas, 74 literatūras avoti, 2 pielikumi. Latviešu valodā. Darbā tika veikta neaizsargātu tallu eļļas taukskābju epoksidēšana, izmantojot in situ ģenerētu peroksietiķskābi. Epoksidētās taukskābes sekojoši tika funkcionalizētas ar dietanolamīnu, trietanolamīnu un trimetilolpropānu, iegūstot 3 dažādus poliolus. Iegūtie polioli tika analizēti ar FTIR un MALDI-TOF MS, kā arī tiem tika noteikti svarīgākie ķīmiskie un fizikālie raksturlielumi. No sintezētajiem polioliem ieguva cietos PU putuplastus, kuriem tika noteiktas fizikāli-mehāniskās īpašības, tādas kā stiprība spiedē, termiskās un termomehāniskās īpašības ar DMA, TGA, un siltumplūsmas mēriekārtu. Iegūtie dati tika salīdzināti ar references cieto PU putuplastu paraugiem, kuri tika iegūti no komerciāli pieejamajiem uzņēmuma “BASF” polioliem, kuri plaši tiek izmantoti industrijā.Synthesis of highly functional polyols from epoxidized tall oil; processing of rigid polyurethane foams and characterization of its physico-mechanical properties. Vanags E., scientific supervisors leading researcher Dr.Sc.Ing. Cābulis U; Prof., Dr.Chem. Arturs Vīksna. Master’s thesis, 87 pages, 34 figures, 17 tables, 74 literature references. In Latvian. In this work unprotected fatty acids of tall oil were epoxidized with in situ generated peroxyacetic acid. Three different bio based polyols were synthesized by functionalizing epoxidized fatty acids with diethanolamine, triethanolamine and trimethylolpropane. Obtained polyols were analyzed by FTIR and MALDI-TOF MS. The most important chemical and physical characteristics of obtained polyols were determined. Synthesized polyols were used to process the samples of rigid PU foam. Physico-mechanical and thermal properties of the rigid PU foam samples were determined by DMA, TGA, compression strength and heat flow meter. Characteristics were compared to the reference samples, which were processed from the commercially available “BASF” polyols
Lossy mode resonance in photonic integrated circuits
No full textThe authors would like to acknowledge the Institute of Solid State Physics, University of Latvia. This research was supported by the European Regional Development Fund project 1.1.1.1/20/A/045 and the European Union's Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.In recent years, the promising phenomenon known as lossy mode resonance (LMR) has garnered significant attention in sensing applications. While existing literature in the field of LMR focuses on optical fiber systems and planar waveguides due to their simplicity, there is an absence of research on systems based on photonic integrated circuits (PICs). This article aims to demonstrate, for the first time, the generation of LMR in PICs with sensitivity and a figure of merit (FOM) comparable to that of optical fibers and planar waveguides. Additionally, the article offers a comparison of various polymer materials such as OrmoClear, OrmoCore and SU-8 for integrated waveguides fabrication. To summarize, the main novelty of the article is the demonstration of the LMR phenomenon in integrated chips and the comparison of different polymers commonly used in photonics to fabricate these chips. Moreover, the authors present a novel fabrication workflow for thick polymer waveguides. Finally, the study compares the experimental results obtained with simulations conducted using the finite element method (FEM) in COMSOL Multiphysics environment. © 2024 --//-- This is an open-access article Edvins Letko, Arturs Bundulis, Edgars Vanags, Gatis Mozolevskis,
Lossy mode resonance in photonic integrated circuits, Optics and Lasers in Engineering, Volume 181, 2024, 108387, ISSN 0143-8166, https://doi.org/10.1016/j.optlaseng.2024.108387 published under the CC BY licence.European Regional Development Fund 1.1.1.1/20/A/045; European Union's Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 739508, project CAMART2
Depression, Anxiety, Stress and Related Stressors in Policing
No full textBakalaura darba mērķis bija noskaidrot, kādi ir depresijas, trauksmes un stresa rādītāji policistiem Latvijā un kādi ir galvenie stresori, kas to ietekmē. Pētījuma izlase: 125 respondenti, iedalīti 2 grupās – Valsts policisti (n = 34) un Pašvaldības policisti (n = 91). Datu iegūšanai izmantota Depresijas, trauksmes un stresa skalas saīsinātā versija (DASS-21), latviešu valodā adaptēja Vanags un Raščevska (Lovibond & Lovibond, 1995, kā minēts Vanags & Raščevska, 2015), kā arī Policijas operacionālā stresa aptauja (PSQ-Op) un Policijas organizatoriskā stresa aptauja (PSQ-Org) (McCreary & Thompson, 2006), kuras Latvijā adaptēja autors. Par nozīmīgākajiem stresoriem darbā Latvijas policisti uzskata organizatoriskos. Pašvaldības policisti uzrāda nozīmīgi augstākus trauksmes un izteiktākus organizatoriskā stresa rādītājus nekā Valsts policisti.The aim of the bachelor's work was to find out what depression, anxiety and stress indicators are for police officers in Latvia and what are the main stressors that affect it. Study sample: 125 respondents, divided into 2 groups - State police officers (n = 34) and Municipal police officers (n = 91). The data is based on the shortened Latvian version of the Depression, anxiety and stress scale (DASS-21) (Lovibond & Lovibond, 1995, as mentioned in Vanags & Raščevska, 2015), as well as the Police Operational Stress Questionnaire (PSQ-Op) and the Police Organizational Stress Questionnaire (PSQ-Org) (PSQ-Org) (McCreary & Thompson, 2006), adapted by the author in Latvia. Latvian police consider organisational stressors to be the most important job stressors. Municipal police show significantly higher anxiety and more pronounced organisational stress rates than State police
Data on the characterization of seaweed, wheat bran, and other food processing byproducts as feasible biosorbents
No full textTraditionally, biosorbents have been used to remove contaminants from polluted water, such as wastewater, landfill leachate, rainwater or drinking water. However, two alternative uses of biosorbents have been proposed relatively recently: the removal of heavy metals from fruit juices by biosorption and the use of saturated biosorbents as animal feed. Because these biosorbents are in contact with food or are used as animal feed, the concentration of contaminants in biosorbents must be known. In addition, the characterization of biosorbents is crucial because biosorbent properties affect both adsorption efficiency and the performance of full-scale biosorbent systems. This article presents data from Fourier transform infrared spectroscopy (FTIR) analysis, and the concentration of toxic metals (determined by ICP-MS) as well as pesticide residues was determined in ten biomass samples, namely, pea skins, straw, seaweed Fucus vesiculosus, wheat bran, rye bran, raspberry seeds, peat, buckwheat husks, highbush blueberry pulp, and blackcurrant pulp. Selected biomass samples were also characterized by scanning electron microscopy (SEM), nitrogen physisorption analysis, and pyrolysis-gas chromatography-mass spectrometry (Py-GC/ MS/FID) analysis. © 2024 The Authors --//-- This is an open access article Artis Robalds, Oskars Bikovens, Aija Dēliņa, Nikolai P. Ponomarev, Oskars Purmalis, Laura Elīna Tomsone, Edgars Vanags, Data on the characterization of seaweed, wheat bran, and other food processing byproducts as feasible biosorbents, Data in Brief, Volume 53, 2024, 110214, ISSN 2352-3409, https://doi.org/10.1016/j.dib.2024.110214 published under the CC BY-NC-ND licence.ERDF No. 1.1.1.2/16/I/001, research proposal No. 1.1.1.2/VIAA/2/18/248. Institute of Solid State Physics, University of Latvia as the 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 CAMART
Latvija in the international logistic services market
No full textBakalaura darba tēma ir „ Latvija starptautiskajā loģistikas pakalpojumu tirgū‖ un tā autors ir Edgars Rjadovs. Darba mērķis ir izpētīt , ko Latvija spēj dot kā loģistikas pakalpojumu sniedzējs pasaulei, veikt secinājumus par esošo situāciju un sniegt priekšlikumus tās uzlabošanai. Darba teorijas daļā ir aprakstīta loģistikas nozare un transportu veidi . Analītiskajā daļā, ir izpētīta Latvijas transportu attīstība, salīdzināti loģistikas uzľēmumu apgrozījumi. Darba praktiskajā daļā autors noskaidroja esošo situāciju loģistikas transporta pakalpojuma tirgū, intervējot divas un aptaujājot deviľas firmas. Darbā ir izmantoti periodiskie izdevumi, grāmatas, zinātniskie raksti, interneta resursi. Darbs sastāv no 63 lapaspusēm, tajā ir iekļauti 3 pielikumi, 6 attēli un 9 tabulas Darbā tika izmantoti 55 literatūras avoti.The author of this bachelor teethes is Edgars Rjadovs and its title is „Latvia in the international logistic services market‖. The aim of this work is to examine what Latvia can give to the worldwide market in logistics, make conclusions about current situation and make propositions on how to improve it. In the theoretical part of this teethes is an overlook on logistics field and the kinds of transportation. In the analytical part is examined the evolution of transportation in Latvia, compared the turnovers of logistics companies in Latvia. In the experimental part is examined the current situation in logistics transportation service market by interviewing two and surveying nine companies. In writing this work there have been used various books on logistics, internet sources, periodicals, scientific articles. This teethes consists of 63 pages with 6 images, 9 tables and 3 attachments. There have been used 55 sources of literature
Community driven mobile application to reduce the risk of Covid-19 infection
No full textBakalaura darba autors Edgars Baumanis izvēlējies tēmu “Sabiedrības virzīta mobilā lietotne Covid-19 infekcijas riska mazināšanai”, atsaucoties uz vīrusa Covid-19 izplatību Latvijā un pasulē un projekta “Jaunās tehnoloģijas Covid-19 pacientu tēmētai monitorēšanai, testēšanai un terapijai (3-T Project)”[4] monitorēšanas risinājuma nepieciešamību. Monitorēšana iekļauj telpas cilvēku skaita ievākšanu, dalībnieku apziņošanu un telpas datu nosūtīšanu uz kopēju datubāzi. Pētījuma realizēšana ir aktuāla darba rakstīšanas laikā, jo Covid-19 turpina ierobežot visu pasauli. Bakalaura darba mērķis ir izpētīt esošas sabiedrības vadītas lietotnes, dažādus cilvēku monitorēšanas risinājumus, kā arī izplānot un realizēt risinājumu, kas atbilst projekta vajadzībām.The author of the bachelor’s thesis Edgars Baumanis has chosen the topic “Community driven mobile application to reduce the risk of Covid-19 infection” referring to the spread of Covid-19 virus in Latvia and the projects “Jaunās tehnoloģijas Covid-19 pacientu tēmētai monitorēšanai, testēšanai un terapijai (3-T Project)”[4]. Monitoring includes gathering the number of people in the room, notifying the participants and sending the room data to a common database. The implementation of the research is relevant at the time of writing, as Covid-19 continues to limit the whole world. The aim of the bachelor’s thesis is to study existing community driven applications, various human monitoring solutions, as well as to plan and implement a solution that meets the needs of the project
Augšējās ekstremitātes pozicionālie perifēro nervu bojājumi anestēzijas laikā un problēmas risinājumi: rokas apdraudējuma biomehāniskā izpēte. Promocijas darba kopsavilkums
No full textResearch was carried out at Department of Anaesthesiology and Reanimatology of Rīga Stradiņš University, Department of Histology and Departement of Pathology of Rīga Stradiņš University, Riga hospital No. 2, Ventspils and Jelgava regional hospitals, State Center for Forensic Medical Examination. Defence: at the meeting of the Theoretical medicine Council of Rīga Stradiņš University on 7. of march, 2011 at 4.00 PM in the Hippocrates’ auditorium of Rīga Stradiņš University, Dzirciema str. 16.Research was carried out with the financial support of European Social Fun
Positional Damages of Peripheral Nerves of the Upper Extremity During Anesthesia and the Problem’s Solution: Biomechanical Investigation of the Arm Threat. Doctoral Thesis
No full textPromocijas darbs veikts Rīgas 2. slimnīcā, Ventspils un Jelgavas daudzprofilu reģionālajās slimnīcās, Valsts tiesu medicīnas centrā un Rīgas Stradiņa universitātes Anestezioloģijas un reanimatoloģijas katedrā, Patoloģijas katedrā un Histoloģijas katedrā. Aizstāvēšana: Teorētiskās medicīnas promocijas padomes sēdē 2011. gada 7. martā plkst. 14.00 Rīgas Stradiņa universitātes Hipokrāta auditorijā Rīgā, Dzirciema ielā 16.Darbs izstrādāts ar Eiropas Sociālā Fonda finansiālu atbalst
Development and implementation of E-services
No full textPakalpojumu elektronizācija mūsdienās darbu padara efektīvāku un ātrāku, kā arī
pakalpojumus pieejamākus plašākam sabiedrības lokam. Pēdējos gados šī tēma kļūst arvien
aktuālāka, tāpēc darbs ir veltīts elektronisko pakalpojumu izstrādei Latvijā. Darbā tiek
aplūkota elektronisko pakalpojumu izstrāde Latvijā, izstrādei nepieciešamā infrastruktūra,
tehnoloģijas un rīki. Tiek aplūkoti elektronisko pakalpojumu izstrādes procesa soļi un to
sastāvdaļas. Aplūkota elektronisko pakalpojumu arhitektūra un standarti. Atsevišķa nodaļa
veltīta BizTalk servera priekšrocībām, izstrādājot elektroniskos pakalpojumus, un paskaidrots,
kā notiek integrācijas servisu izstrāde, izmantojot BizTalk orķestrācijas. Darba kontekstā
autors izstrādā elektronisko pakalpojumu „Mani dati cukura diabēta pacientu reģistrā”.
Atslēgvārdi: e-pakalpojums, XML shēma, IS serviss, BizTalk serveris, BizTalk orķestrācijaThe electronization of services nowadays is making work more effective and faster, also the services are more available to a bigger part of the society. The last years this topic gets more and more urgent, for that reason the work is dedicated to the development of electronic services in Latvia. In the work is examined the development of electronic services in Latvia, the necessary infrastructure for the development, technologies and gadgets. There are examined the steps of the process developing the electronic services and its components. Examined are the architecture and standards of electronic services. A separate chapter is dedicated to the advantages of the BizTalk server developing electronic services and it is explained, how goes on the integration service developing using the BizTalk orchestrations. The Author is developing an electronic service „ My data from patients with diabetes mellitus register” in his work.
Keywords: e-service, XML schema, IS service, BizTalk server, BizTalk orchestratio
Changes of sediment properties during the development of Lielais Svētiņu Lake
No full textEdgars GALGĀNS, 2010. Nogulumu īpašību izmaiņas Lielā Svētiņu ezera attīstības laikā. Bakalaura darbs dabaszinātņu bakalaura grāda iegūšanai dabaszinātnēs. Latvijas Universitāte, Ģeogrāfijas un Zemes zinātņu fakultāte. Rīga.
Bakalaura darba mērķis ir raksturot Lielā Svētiņu ezera nogulumu īpašību izmaiņas ezera attīstības laikā., izmantojot karsēšanas zudumu analīzi, datus par organisko vielu un karbonātu satura izmaiņām, kā arī 14C nogulumu datējumus. Darbā aprakstīti un izklāstīti uzdevumi izvirzītā mērķa sasniegšanai.
Darba gaitā autors iepazinās ar pieejamo literatūru, tai skaitā arī ar interneta resursiem par ezeriem, Mazo Svētiņa ezeru, Lubāna līdzenumu, Austrumlatvijas zemieni. Darbā sniegts apraksts par metodēm, kuras izmantotas pētījumā, kā arī rezultāti, kas iegūti Lielā un Mazā Svētiņu ezeru nogulumu lauka un laboratorijas pētījumos. Autors apguva un veica karsēšanas zudumu analīzi 761 paraugam.
Darbs apkopots četrās nodaļās, kuru izklāstā iegūstama informācija par to Austrumlatvijas zemieni. Darbā aplūkota informācija par Lielo un Mazo Svētiņu ezeriem. Darbā dots padziļināts Lielā Svētiņu ezera raksturojums.
Pētniecisko daļu sastāda bakalaura darbā izmantoto materiālu un metožu apraksts, karsēšanas zudumu analīžu rezultāti, to interpretācija.
Darba literāro informāciju papildina kartogrāfiskais materiāls, attēli un autora izveidots pielikums par Lielā un Mazā Svētiņu ezeru dziļuma mērījumiem ar eholoti dati, kā arī divu zondējumu fotogrāfijas.
Bakalaura darbs satur
53 lappuses, 23 attēlus, 1 tabulu un 2 pielikumus.
Atslēgas vārdi: Lielais Svētiņu ezers, Lubāna līdzenums, karsēšanas zudumu analīzeEdgars GALGANS, 2010. Changes of Sediment Properties During the Development of Lielais Svetinu Lake.
Bachelor’s Theses for Graduation of Natural Sciences Bachelor’s degree in Geography. University of Latvia, Faculty of Geography and Earth Science. Riga.
Edgars GALGĀNS, 2010.
The aim of Bachelor thesis is to characterise changes of the sediment properties during the development of Lielais Svētiņu Lake by applying LOI analysis, data of content of carbonates and organic matter, as well as, data of sediment 14C dating. Tasks to achieve the aim are described.
Author studied publications, information from the internet on lakes, Lielais un Mazais Svētiņu Lakes, Lubans Plain and Austrumlatvia Lowland. Descriptions of the methods used for investigation have been given, as well as results from Lielais Svētiņu Lake sediment field and laboratory investigations. Author acquired and performed LOI analyses for 761 sample.
Thesis contains four chapters, which include information on Austrumlatvia Lowland, Lubans Plain and detailed information and characteristics on Lielais Svētiņu Lake.
Scientific part of the thesis includes description of the obtained materials and data and their interpretation.
The text of thesis is supplemented by maps, figures and appendix of raw data prepared by author of depth measurements in the Lielais Svētiņu and Mazais Svētiņu Lakes, as well as photos of sounding.
Bachelor thesis contains 53 pages, 23 figures, 1 table and 2 appendixes.
Key words: Lubāns plain, Lielais and Mazais Svētiņu lakes, Loss on ignition (LOI) analysi
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