50 resultados para electronic conducting polymers
Resumo:
Diplomityössä kartoitetaan tiedon laatuun vaikuttavia tekijöitä kirjallisuuden pohjalta sekä tutkitaan empiirisesti sähköisen reseptin tietosisällön laatua toiminnallisuuden näkökulmasta tarkasteltuna. Tutkimuksen tavoitteena on tuottaa esiselvitys Reseptikeskuksen tietosisällön toiminnallisesta laadusta käytettäväksi lähtötietona tiedon laadun arviointiin ja seurantaan. Tutkimuksen empiirinen osuus toteutettiin kvantitatiivisena tutkimuksena analysoimalla Reseptikeskuksen tietosisällöstä poimittua n. 600 potilaan otosta. Tutkitussa tietosisällössä havaittiin joitain poikkeamia tietosisältöä koskeviin määrityksiin verrattuna, mutta merkittäviä eroja terveydenhuollon eri toimijaryhmien apteekeissa, julkisella ja yksityisellä sektorilla kirjaamien reseptien tietosisällön laadussa ei havaittu. Tiedon kontekstisidonnaisuus on keskeinen tekijä tiedon toiminnallisen laadun määrittämisessä, arvioinnissa ja kehittämisessä. Toiminnan kannalta merkityksellinen tieto rakentuu dataan liitettyjen merkitysten, tiedon käyttäjien kokemusten sekä teknisen ja sosiaalisen käyttöympäristön muodostamana kokonaisuutena. Tiedon laadun parantaminen on jatkuva prosessi, jota tulee ylläpitää arvioimalla ja kehittämällä käytettäviä laatumittareita ja analysointimalleja. Reseptikeskuksen tietosisällön laatua voidaan edelleen kehittää ja nyt tehdyn esikartoituksen pohjalta voidaan jatkossa seurata tietosisällön laadun kehittymistä uusien tutkimusten avulla
Power Electronic Converters in Low-Voltage Direct Current Distribution – Analysis and Implementation
Resumo:
Over the recent years, smart grids have received great public attention. Many proposed functionalities rely on power electronics, which play a key role in the smart grid, together with the communication network. However, “smartness” is not the driver that alone motivates the research towards distribution networks based on power electronics; the network vulnerability to natural hazards has resulted in tightening requirements for the supply security, set both by electricity end-users and authorities. Because of the favorable price development and advancements in the field, direct current (DC) distribution has become an attractive alternative for distribution networks. In this doctoral dissertation, power electronic converters for a low-voltage DC (LVDC) distribution system are investigated. These include the rectifier located at the beginning of the LVDC network and the customer-end inverter (CEI) on the customer premises. Rectifier topologies are introduced, and according to the LVDC system requirements, topologies are chosen for the analysis. Similarly, suitable CEI topologies are addressed and selected for study. Application of power electronics into electricity distribution poses some new challenges. Because the electricity end-user is supplied with the CEI, it is responsible for the end-user voltage quality, but it also has to be able to supply adequate current in all operating conditions, including a short-circuit, to ensure the electrical safety. Supplying short-circuit current with power electronics requires additional measures, and therefore, the short-circuit behavior is described and methods to overcome the high-current supply to the fault are proposed. Power electronic converters also produce common-mode (CM) and radio-frequency (RF) electromagnetic interferences (EMI), which are not present in AC distribution. Hence, their magnitudes are investigated. To enable comprehensive research on the LVDC distribution field, a research site was built into a public low-voltage distribution network. The implementation was a joint task by the LVDC research team of Lappeenranta University of Technology and a power company Suur-Savon S¨ahk¨o Oy. Now, the measurements could be conducted in an actual environment. This is important especially for the EMI studies. The main results of the work concern the short-circuit operation of the CEI and the EMI issues. The applicability of the power electronic converters to electricity distribution is demonstrated, and suggestions for future research are proposed.
Resumo:
Electrochromism, the phenomenon of reversible color change induced by a small electric charge, forms the basis for operation of several devices including mirrors, displays and smart windows. Although, the history of electrochromism dates back to the 19th century, only the last quarter of the 20th century has its considerable scientific and technological impact. The commercial applications of electrochromics (ECs) are rather limited, besides top selling EC anti-glare mirrors by Gentex Corporation and airplane windows by Boeing, which made a huge commercial success and exposed the potential of EC materials for future glass industry. It is evident from their patents that viologens (salts of 4,4ʹ-bipyridilium) were the major active EC component for most of these marketed devices, signifying the motivation of this thesis focusing on EC viologens. Among the family of electrochromes, viologens have been utilized in electrochromic devices (ECDs) for a while, due to its intensely colored radical cation formation induced by applying a small cathodic potential. Viologens can be synthesized as oligomer or in the polymeric form or as functionality to conjugated polymers. In this thesis, polyviologens (PVs) were synthesized starting from cyanopyridinium (CNP) based monomer precursors. Reductive coupling of cross-connected cyano groups yields viologen and polyviologen under successive electropolymerization using for example the cyclic voltammetry (CV) technique. For further development, a polyviologen-graphene composite system was fabricated, focusing at the stability of the PV electrochrome without sacrificing its excellent EC properties. High electrical conductivity, high surface area offered by graphene sheets together with its non-covalent interactions and synergism with PV significantly improved the electrochrome durability in the composite matrix. The work thereby continued in developing a CNP functionalized thiophene derivative and its copolymer for possible utilization of viologen in the copolymer blend. Furthermore, the viologen functionalized thiophene derivative was synthesized and electropolymerized in order to explore enhancement in the EC contrast and overall EC performance. The findings suggest that such electroactive viologen/polyviologen systems and their nanostructured composite films as well as viologen functionalized conjugated polymers, can be potentially applied as an active EC material in future ECDs aiming at durable device performances.