Hybrid density functional study of oxygen vacancies in KTaO3 and NaTaO3

Using the Heyd-Scuseria-Ernzerhof hybrid functional, we systematically study the energetics and electronic properties of oxygen vacancies in KTaO3 and NaTaO3. The oxygen vacancies in these systems show similar behavior. The 2+ charge state is the most stable for most positions of the Fermi level inside the band gap. The neutral and + charge states become comparable in formation energy with the 2+ charge state when the Fermi level is close to the conduction band minimum. Therefore, the oxygen vacancies are double shallow donors, which can provide carrier electrons. Two types of off-symmetric configurations, in which the two nearest tantalum atoms of the oxygen vacancies are asymmetrically located, also possibly form as metastable configurations. These metastable configurations show a striking difference in electronic structure from each other; one configuration has a delocalized characteristic as in the case of the stable configuration, while the other induces a deep, localized state in the band gap. On the basis of the predicted formation energies and electronic properties, the previous experimental and theoretical findings relevant to the oxygen vacancies are discussed

Doping of hexagonal boron nitride via intercalation: A theoretical prediction

A doping strategy for hexagonal boron nitride (h-BN) is proposed through hybrid Hartree-Fock density functional calculations. Unlike their behavior in typical semiconductors, substitutional dopants generate deep and localized in-gap states in h-BN. In contrast, intercalated atoms with high and low electronegativities perturb the host valence and conduction bands weakly, resulting in shallow acceptor and donor states, respectively. The formation of defect complexes involving substitutional dopants suppresses the migration of the intercalated dopants, with the shallow acceptor or donor characteristics preserved. The strategy proposed here is also applicable to h-BN ultrathin layers and extendable to the doping of BN single sheets via adsorption

Konfigurering och ibruktagning av KNX system

Detta examensarbete behandlar grunderna i KNX samt programmering av KNX enheter med datorprogrammet ETS 4. I arbetet beskrivs hur KNX systemet fungerar, hur det är uppbyggt och de olika överföringsmedium som kan användas då KNX enheter kommunicerar. Jag beskriver också hur ETS 4 installeras på datorn och hur man kommer igång med programmeringen av KNX enheterna. Inför detta examensarbete har jag studerat en del av ABB:s KNX enheter samt deras funktioner och konfigurationsmöjligheter. Syftet med detta examensarbete är att skapa en liten handbok för hur ett KNX system är uppbyggt samt hur KNX enheterna programmeras med ETS 4.Tämä opinnäytetyö käsittelee KNX:n perusteita ja KNX-laitteiden ohjelmointia ETS 4 tietokoneohjelman avulla. Työssä kuvaillaan, miten KNX-järjestelmä toimii, millä tavalla se on rakennettu sekä mitä eri siirtomedioita voidaan käyttää KNX-laitteiden viestinnässä. Työssä kuvaillaan myös, miten ETS-ohjelma asennetaan tietokoneella ja miten päästään aloittamaan KNX-laitteiden ohjelmointi. Ennen tätä opinnäytetyötä kirjoittaja on opiskellut ABB:n KNX-laitteita sekä niiden toimintoja ja konfiguraatiomahdollisuuksia. Opinnäytetyön tarkoituksena on tehdä pieni käsikirja, joka kertoo, miten KNX- järjestelmä on rakennettu sekä millä tavalla KNX-laitteet ohjelmoidaan ETS 4:llä.In this thesis I deal with the basics of KNX as well as the programming of KNX devices with the computer software ETS 4. In the thesis I describe how the KNX system works, how it is built and the different communication media that are used for communication between KNX devices. I also describe how ETS 4 is installed on a personal computer and how to get started with the programming of the KNX devices. When preparing for this thesis I studied a part of ABB’s KNX devices, their functions as well as their configuration possibilities. The purpose of this thesis is to create a small manual that can be used to see how a KNX system is built and to check how KNX devices are programmed with ETS 4

On the weights of end-pairs in n-end catenoids of genus zero

First principles calculations are carried out to analyze adsorption of CO and H2 molecules on a Pt (111) surface and the effect of surface strain on the adsorption energy. A CO molecule is more adsorptive on the Pt (111) surface than a H2 molecule under an ordinary condition. Surface expansion enhances CO poisoning on a Pt (111) surface. On the contrary, a compressive strain reduces adsorptive strength of a CO molecule. Similar tendency is also found in adsorption of a H2 molecule on the bridge, fcc-hollow, and hcp-hollow sites. However, H2 adsorption on the top site is less affected by the strain. As a consequence, the difference of adsorption energies between CO and H2 molecules becomes smaller when compressive strain is introduced into the Pt (111) surface. Based on thermodynamics, surface coverage ratio is quantitatively evaluated with taking into account the effect of surface strain and partial pressure of gas phase. It is revealed that compressive strain improves probability of H2 adsorption on Pt surface

Rakennusautomaation vastaanoton kehittäminen

Rakennusautomaation vastaanotto ja siihen liittyvät toimintakokeet ovat keskeisiä vaiheita rakennusautomaatioprojektin laadun varmennuksessa. Senaatti-kiinteistöjen talotekniikan asiantuntija Timo Keskikuru oli havainnut koko alaa koskevia puutteita vastaanottoprosessissa ja toivoi asiaa tutkittavan. Työn tavoitteena oli kehittää rakennusautomaation vastaanoton toimintatapoja. Työssä selvitettiin aiheeseen liittyviä säännöksiä ja toimintatapoja kirjallisista lähteistä. Kehitystyön kannalta tärkein tutkimismenetelmä oli alan eri toimijoiden haastattelut. Käytännön kokemuksia saatiin pilottikohteesta, jossa kehitystyön tuloksia testattiin. Työssä kehitettiin vastaanoton tueksi myös tarkastusdokumentointia. Vastaanoton kehittämistarpeet nousivat työn aikana selvästi esille. Dokumentoinnin kehittämiseen on tulevaisuudessa varattava lisää resursseja, jotta laajempi uudistus vallitseviin käytäntöihin olisi mahdollinen. Myös vastaanoton toimintatapojen uudistaminen koko rakennusautomaatioalalla vaatii loppuun asti kehitettyjä ohjeistuksia ja valmiita dokumentteja, jotka myös otetaan käyttöön.Acceptance of building automation and functional test are important subjects when developing building automation system projects. Timo Keskikuru, Expert in Building Services Engineering in Senaatti-Kiinteistöt, had noticed some deficiencies in the acceptance procedure and wanted a research to be done. The goal was to a develop procedure for building automation acceptance. In the execution rules and working policies were studied from literature of the field. The most important way of research was interviews of professionals from different perspectives. Practical experience was gathered in a pilot project, which gave an opportunity to test some results of the development. As a result, a documentation was developed to support acceptance. The need of development in acceptance was clear. More resources must be given to research and development of documentation to reform the procedure more. Also documents and instructions must be properly improved and finished to make difference in larger scale