120 resultados para Ti-Ni alloys
Sredi balovnej i pasynkov" prirody: (Stambul"-Monako-Finlândìâ) : Vpečatlěnìâ i mysli turista
Resumo:
The Pasvik monitoring programme was created in 2006 as a result of the trilateral cooperation and with the intention of following changes in the environment under variable pollution levels. Water quality is one of the basic elements of the programme when assessing the effects of the emissions from the Pechenganikel mining end metallurgical industry (Kola GMK). In this report temporal trends of the water chemistry during 2000–2013 are examined on the basis of the data gathered from lake Inari, River Pasvik and directly connected lakes, Lake Kuetsjarvi and 25 small lakes in three areas: Pechenganikel (Russia), Jarfjord (Norway) and Vätsäri (Finland). The lower parts of the Pasvik watercourse are impacted by both atmospheric pollution and direct wastewater discharge from the Pechenganikel smelter and the settlement of Nikel. The upper section of the watercourse and the small lakes and streams which are not directly linked to the Pasvik Watercourse only receive atmospheric pollution. Lake Inari is free of direct emissions from the Pechenganikel and the water quality is excellent. In River Pasvik and the directly connected lakes copper, nickel, and sulphates are the main pollutants. The most polluted water body is the Kolosjoki River as well as the stream connecting the Lakes Salmijarvi and Kuetsjarvi. The concentration of metals and sulphates in the water notably increases downstream the river lower Lake Kuetsjarvi. In Lake Kuetsjarvi copper and nickel concentrations are clearly elevated and have changed insignificantly in the last years of the research period. In the small border area lakes recovery from acidification in Vätsäri and Jarfjord is evident. Nickel and copper oncentrations have fluctuated but remained on clearly elevated level in Jarfjord and Pechenga. Copper concentrations have been slightly rising in the recent years. In Pechenga area nickel concentrations during the last four monitoring years are decreasing in some places but the regional trend through whole time series is still positive.
Resumo:
In this thesis properties and influence of modification techniques of porous silicon were studied by Atomic Force Microscope (AFM). This device permits to visualize the surface topography and to study properties of the samples on atomic scale, which was necessary for recent investigation. Samples of porous silicon were obtained by electrochemical etching. Nickel particles were deposited by two methods: electrochemical deposition and extracting from NiCl2 ethanol solution. Sample growth was conducted in Saint-Petersburg State Electrotechnical University, LETI. Kelvin probe force microscopy (KPFM) and Magnetic force microscopy (MFM) were utilized for detailed information about surface properties of the samples. Measurements showed the difference in morphology correlating with initial growth conditions. Submicron size particles were clearly visible on surfaces of the treated samples. Although their nature was not clarified due to limitations of AFM technique. It is expected that surfaces were covered by nanometer scale Ni particles, which can be verified by implication of RAMAN device.
First-principles study on electronic and structural properties of Cu(In/Ga)Se alloys for solar cells
Resumo:
Thin-film photovoltaic solar cells based on the Cu(In1−xGax)Se2 (CIGS) alloys have attracted more and more attention due to their large optical absorption coefficient, long term stability, low cost, and high efficiency. Modern theoretical studies of this material with first-principles calculations can provide accurate description of the electronic structure and yield results in close agreement with experimental values, but takes a large amount of calculation time. In this work, we use first-principles calculations based on the computationally affordable meta- generalized gradient approximation of the density-functional theory to investigate electronic and structural properties of the CIGS alloys. We report on the simulation of the lattice parameters and band gaps, as a function of chemical composition. The obtained results were found to be in a good agreement with the available experimental data.
Resumo:
Invokaatio: J.M.G.
Resumo:
The need for reduced intrinsic weight of structures and vehicles in the transportation industry has made aluminium research of interest. Aluminium has properties that are favourable for structural engineering, including good strength-to-weight ratio, corrosion resistance and machinability. It can be easily recycled saving energy used in smelting as compared to steel. Its alloys can have ultimate tensile strength of up to 750 MPa, which is comparable to steel. Aluminium alloys are generally weldable, however welding of high strength alloys like the 7xxx series pose considerable challenges. This paper presents research on the weldability of high strength aluminium alloys, principally the 7xxx series. The weldability with various weld processes including MIG, TIG, and FSW, is discussed in addition to consideration of joint types, weld defects and recommendations for minimizing or preventing weld defects. Experimental research was carried out on 7025-T6 and AW-7020 alloys. Samples were welded, and weld cross sections utilized in weld metallurgy studies. Mechanical tests were carried out including hardness tests and tensile tests. In addition, testing was done for the presence of Al2O3 on exposed aluminium alloy. It was observed that at constant weld heat input using a pulsed MIG system, the welding speed had little or no effect on the weld hardness. However, the grain size increased as the filler wire feed rate, welding current and welding speed increased. High heat input resulted in lower hardness of the weld profile. Weld preheating was detrimental to AW- 7020 welds; however, artificial aging was beneficial. Acceptable welds were attained with pulsed MIG without the removal of the Al2O3 layer prior to welding. The Al2O3 oxide layer was found to have different compositions in different aluminium alloys. These findings contribute useful additional information to the knowledge base of aluminium welding. The application of the findings of this study in welding will help reduce weld cost and improve high strength aluminium structure productivity by removing the need for pre-weld cleaning. Better understanding of aluminium weld metallurgy equips weld engineers with information for better aluminium weld design.
Resumo:
Tutkimuksemme päätarkoituksena on ollut tutkia perheen osallisuutta kehitysvammaisen lapsen kuntoutuksen suunnitteluun kuntoutussuunnitelman ja henkilökohtaisen opetuksen järjestämistä koskevan suunnitelman eli HOJKS:n pohjalta. Vertailimme myös HOJKS:n ja kuntoutussuunnitelman yhtäläisyyksiä ja eroavaisuuksia. Opinnäytetyö osallistuu Varsinais-Suomen erityishuoltopiirin, Kansaneläkelaitoksen, Turun yliopistollisen keskussairaalan ja Turun yliopiston yhteiseen KeLaKuVa -tutkimushankkeeseen. Aineistomme koostuu 25 kuntoutussuunnitelmasta ja 16 HOJKS:sta sekä yhdestä varhaiskasvatussuunnitelmasta. Suunnitelmia tutkittiin sisällönanalyysin avulla aineistolähtöisesti ja myöhemmässä vaiheessa teoriaohjaavasti. Perheen ääni vaikuttaa kuuluvan hyvin kuntoutusprosessin suunnitteluvaiheessa käytössämme olleen aineiston perusteella. Lapsen kuntoutukselle asetetut tavoitteet ovat yhteneväiset kuntoutussuunnitelman ja HOJKS:n välillä, mikä on lapsen edun mukaista. Toisaalta suunnitelmien välillä on myös eroja painotuksissa: HOJKS:ssa korostuvat akateemiset taidot ja kuntoutussuunnitelmassa terapiat. Tämä puoltaa tarvetta molemmille suunnitelmille.