16 resultados para Elemental analyses measurements
em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland
Resumo:
Tss tyss on esitetty vsyttvn kuormituksen mittaamiseen ja mittausdatan jlkiksittelyyn sek vsymismitoitukseen liittyvi menetelmi. Menetelmien sovelluskohteena oli metskoneen kuormain, joka on vsyttvsti kuormitettu hitsattu rakenne. Teoriaosassa on kuvattu vsymisilmit ja vsymismitoitusmenetelmi sek kuormitusten tunnistamiseen ja mittausten jlkiksittelyyn liittyvi menetelmi. Yleisimmin kytettyjen vsymismitoitusmenetelmien rinnalle on esitetty luotettavuuteen perustuvaa vsymismitoitusmenetelm. Kuormainten suunnittelussa on keveys- j a kestoikvaatimusten takia erityisen suuri merkitys vsymisen huomioimisella. Rakenteille on ominaista tietyt toiminnan kannalta vlttmttmt hitsatut yksityiskohdat, jotka usein mrvt koko rakenteen kestoin. Koska nm ongelmakohdat pystytn useimmiten tunnistamaan jo suunnitteluvaiheessa, voidaan yksityiskohtien muotoilulla usein parantaa huomattavasti koko rakenteen kestoik. Niden yksityiskohtien optimointi on osittain mahdollista toteuttaa ilman kuormituskertymtietoa, mutta useimmiten kuormitusten tunnistaminen on edellytys parhaan ratkaisun lytymiselle. Tllin toistaiseksi paras keino todellisen vsyttvn kuormituksen tunnistamiseksi on pitkaikaiset kenttmittaukset. Kenttmittauksilla selvitetn rakenteeseen kohdistuvat kuormitukset venymliuskojen avulla. Kuormitusten tunnistamisella on erityisen suuri merkitys kun halutaan mritt rakenteen kestoik. Vsyminen ja vsyttv kuormitus ovat kuitenkin tilastollisia muuttujia j a yksittiselle rakenteelle ei ole mahdollista mritt tarkkaa k estoik. Tilastollisia menetelmi kytten on kuitenkin mahdollista mritt rakenteen vaurioitumisriski. Laskettaessa vaurioitumisriski suurelle mrlle yksittisi rakenteita voidaan muodostaa tarkkojakin ennusteita mahdollisten vaurioiden lukumrst. Tllin kuormituskertymtiedosta voi olla tavanomaisen suunnittelun lisksi laajempaa hyty esimerkiksi takuuksittelyss. Tss tyss on sovellettu esitettyj teorioita kytnnss metskoneen harvesterin puomiston vsymistarkasteluun. Kyseisen rakenteen kuormituksia mitattiin kahden viikon aikana yhteens 35 tuntia, jonka perusteella laskettiin vsyttvn kuormituksen tilastollinen jakauma esimerkkitapaukselle. Mittauksen perusteella ei voitu tehd kuitenkaan johtoptksi tuotteen koko elinkaaren kuormituksista eik muiden samanlaisten tuotteiden kuormituksista, koska mitattu otos oli suhteellisen lyhyt ja rajoittui vain yhteen kyttjn ja muutamaan kyttkohteeseen. Menetelmien testaamiseksi kyseinen otos oli kuitenkin riittv. Kuormituskertymtietoa kytettiin hyvksi mys laatumritysten muodostamisessaesimerkkitapaukselle. Murtumismekaniikkaan perustuvalla menetelmll arvioitiinharvesteripilarin valun mahdollisten valuvirheiden suurin sallittu koko. Luotettavuuteen pohjautuvan mitoitusmenettelyn tarve nytt olevanlisntymss, joten pitkaikaisten kenttmittausten tehokas hydyntminen tulee olemaan keskeinen osa vsymismitoitusta lhitulevaisuudessa. Menetelmi olisi mahdollista tehostaa yhdistmll kuormituskertymn erilaisia kuormitusten suhteen riippuvia tunnettuja suureita kuten ksiteltvn puun halkaisija. Todellisettuotekohtaiset tilastolliset jakaumat kuormituksista voitaisiin muodostaa mahdollisesti tehokkaammin, jos esimerkiksi kuormitusten riippuvuus metstyypist pystyttisiin ensin mrittmn.
Resumo:
A total of over 200 different samples of bark and wood of Silver birch, Norway spruce and Scots pine were analysed. Samples were taken from several areas in western Finland, some with known sources of atmospheric heavy metal emission (Harjavalta, Ykspihlaja). Also analytical data for pine needles from some sites are reported. The chemical analyses were performed by thick-target particle-induced X-ray emission (PIXE) spectrometry after preconcentration by dry ashing of samples at 550oC. The following elements were quantified in most of the samples: P, S, K, Ca, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Cd, Ba and Pb. The ash percentage and the chemical composition of ashes of different wood materials were also obtained, as dry ashing was used in the analytical procedure. The variations in elemental concentrations in wood and bark of an individual tree, expressed as RSDs, were mostly in the range 10 20 %. For several trees of the same species sampled from small areas (< 1 ha), the variations in elemental concentrations were surprisingly high (RSDs 20 50 %). In the vicinity of metal plants, effects of strong atmospheric heavy metal pollution (pollution factor above 100) were observed in pine bark. The increase of heavy metal content in wood samples from the same sites was quite small. Elemental concentrations in ashes of bark and wood, from areas with no local source of atmospheric pollution, were relatively uniform. Based on this observation an alternative way of demonstrating atmospheric pollution of tree bark is discussed.
Resumo:
PIXE (Particle Induce X-ray Emission spectrometry) was used for analysing stem bark and stem wood of Scots pine, Norway spruce and Silver birch. Thick samples were irradiated, in laboratory atmosphere, with 3 MeV protons and the beam current was measured indirectly using a photo multiplicator (PM) tube. Both point scans and bulk analyses were performed with the 1 mm diameter proton beam. In bulk analyses, whole bark and sectors of discs of the stem wood were dry ashed at 550 C. The ashes were homogenised by shaking and prepared to target pellets for PIXE analyses. This procedure generated representative samples to be analysed, but the enrichment also enabled quantification of some additional trace elements. The ash contents obtained as a product of the sample preparation procedure also showed to be of great importance in the evaluation of results in environmental studies. Spot scans from the pith of pine wood outwards, showed clearly highest concentrations of manganese, calcium and zinc in the first spot irradiated, or 2-3 times higher than in the surrounding wood. For stem wood from the crown part of a pine this higher concentration level was found in the first four spots/mms, including the pith and the two following growth rings. Zinc showed increasing concentrations outwards in sapwood of the pine stem, with the over-all lowest concentrations in the inner half of the sapwood. This could indicate emigration of this element from sapwood being under transformation to heartwood. Point scans across sapwood of pine and spruce showed more distinct variations in concentrations relative to hearth wood. Higher concentrations of e.g. zinc, calcium and manganese were found in earlywood than in denser latewood. Very high concentrations of iron and copper were also seen for some earlywood increments. The ash content of stem bark is up to and order higher than for the stem wood. However, when the elemental concentration in ashes of bark and wood of the same disc were compared, these are very similar this when trees are growing at spots with no anthropogenic contamination from the atmosphere. The largest difference was obtained for calcium which appeared at two times high concentrations in ashes of bark than in ashes of the wood (ratio of 2). Pine bark is often used in monitoring of atmospheric pollution, where concentrations in bark samples are compared. Here an alternative approach is suggested: Bark and the underlying stem wood of a pine trees are dry ashed and analysed. The elemental concentration in the bark ash is then compared to the concentration of the same element in the wood ash. Comparing bark to wood includes a normalisation for the varying availability of an element from the soil at different sites. When this comparison is done for the ashes of the materials, a normalisation is also obtained for the general and locally different enrichment of inorganic elements from wood to bark. Already a ratio >2 between the concentration in the bark ash and the concentration in the wood ash could indicate atmospheric pollution. For monitoring where bark is used, this way of inwards comparison is suggested - instead of comparing to results from analyses of bark from other trees (read reference areas), growing at sites with different soil and, locally, different climate conditions. This approach also enables evaluation of atmospheric pollution from sampling of only relative few individual trees preferable during forest felling.
Resumo:
The papermaking industry has been continuously developing intelligent solutions to characterize the raw materials it uses, to control the manufacturing process in a robust way, and to guarantee the desired quality of the end product. Based on the much improved imaging techniques and image-based analysis methods, it has become possible to look inside the manufacturing pipeline and propose more effective alternatives to human expertise. This study is focused on the development of image analyses methods for the pulping process of papermaking. Pulping starts with wood disintegration and forming the fiber suspension that is subsequently bleached, mixed with additives and chemicals, and finally dried and shipped to the papermaking mills. At each stage of the process it is important to analyze the properties of the raw material to guarantee the product quality. In order to evaluate properties of fibers, the main component of the pulp suspension, a framework for fiber characterization based on microscopic images is proposed in this thesis as the first contribution. The framework allows computation of fiber length and curl index correlating well with the ground truth values. The bubble detection method, the second contribution, was developed in order to estimate the gas volume at the delignification stage of the pulping process based on high-resolution in-line imaging. The gas volume was estimated accurately and the solution enabled just-in-time process termination whereas the accurate estimation of bubble size categories still remained challenging. As the third contribution of the study, optical flow computation was studied and the methods were successfully applied to pulp flow velocity estimation based on double-exposed images. Finally, a framework for classifying dirt particles in dried pulp sheets, including the semisynthetic ground truth generation, feature selection, and performance comparison of the state-of-the-art classification techniques, was proposed as the fourth contribution. The framework was successfully tested on the semisynthetic and real-world pulp sheet images. These four contributions assist in developing an integrated factory-level vision-based process control.
Resumo:
In this bachelor's thesis a relay card for capacitance measurements was designed, built and tested. The study was made for the research and development laboratory of VTI Technologies, which manufactures capacitive silicon micro electro mechanical accelerometers and pressure sensors. As the size of the sensors is decreasing the capacitance value of the sensors also decreases. The decreased capacitance causes a need for new and more accurate measurement systems. The technology used in the instrument measuring the capacitance dictates a framework how the relay card should be designed, thus the operating principle of the instrument must be known. To achieve accurate results the measurement instrument and its functions needed to be used correctly. The relay card was designed using printed circuit board design methods that minimize interference coupling to the measurement. The relay card that was designed in this study is modular. It consists of a separate CPU card, which was used to control the add-on cards connected to it. The CPU card was controlled from a computer through a serial bus. Two add-on cards for the CPU card were designed in this study. The first one was the measurement card, which could be used to measure 32 capacitive sensors. The second add-on card was the MUX card, which could be used to switch between two measurement cards. The capacitance measurements carried out through the MUX card and the measurement cards were characterized with a series of test measurements. The test measurement data was then analysed. The relay card design was confirmed to work and offer accurate measurement results up to a measurement frequency of 10 MHz. The length of the measurement cables limited the measurement frequency.
Resumo:
Tiivistelm: TDR-mittausten kalibrointi viljeltyjen turvemaiden kosteuden mittaamiseen
Resumo:
Selostus: Hiehojen elopainon mrittminen mittauksin alkukasvatusvaiheessa
