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Author:Ojala, Olli
Title:Enhancement of X-ray analyzer measurements utilizing Deterministic-Stochastic Subspace Identification
Röntgenfluoresenssianalysaattorin mittausten parantaminen aliavaruusidentifiointia hyväksikäyttäen
Publication type:Master's thesis
Publication year:2004
Pages:55      Language:   eng
Department/School:Puunjalostustekniikan osasto
Main subject:Systeemitekniikka   (AS-74)
Supervisor:Hyötyniemi, Heikki
Instructor:Miettunen, Jorma
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Location:P1 Ark TKK  241   | Archive
Keywords:subspace identification
dynamic models
Kalman filter
measurement noise
aliavaruusidentifiointi
dynaamiset mallit
Kalmansuodatin
mittauskohina
Abstract (eng): In this study, multivariate data analysis is applied to enhance measurements of an X-ray analyser.
X-ray analyser is used for the determination of mineral contents in the mineral slurry.
Traditionally, enhancement of measurements is carried out by exponential smoothing.
However, the filtered signals are then always delayed and cannot react rapidly to the changes in the measurements.
In this study, deterministic-stochastic subspace identification algorithm N4SID was applied to construct optimized Kalman filters for zinc, copper and iron channels.

The filtering results showed that the outputs of the Kalman filter models seemed to react more rapidly to the changes in the data than the outputs of the first order exponential smoothing but in the same time Kalman filter rejected the measurement noise.

In addition, the image analysis was utilized to enhance the concentration measurements of zinc mineral.
A colour CCD-camera was installed above of the flotation cell, which grabbed images from the froth.
Images were transferred to the image analysis application, which calculated different several of the froth.

The research results in the past have shown that there exists a good correlation between the mean red colour intensity that reflects from the froth and the zinc concentration in the sample.
This correlation was utilized for enhancement of measurements.
The slightly filtered mean red intensities were used for construction of Kalman filters.
The Kalman filtered measurements gave encouraging results when the correlation was good between mean red intensity and zinc concentration.
Abstract (fin): Tässä tutkimuksessa sovellettiin monimuuttuja-analyysiä röntgenfluoresenssianalysaattorin mittausten parantamiseen.
Mittausten suodatus on tavallisesti suoritettu eksponentiaalisuodatusta hyväksikäyttäen.
Se on kuitenkin viiveellinen mittauksiin nähden mikä tulee esiin sen heikkoutena reagoida datassa esiintyviin nopeisiin muutoksiin.
Tämän vuoksi tutkittiin deterministis-stokastisen aliavaruusidentifiointialgoritmin (N4SID) soveltuvuutta optimaalisen Kalman-suodattimen rakentamiseen sinkki-, kupari- ja rautapitoisuusmittauksia varten.

Tuloksia verrattiin ensimmäisen kertaluvun exponentiaalisuodatuksen arvoihin.
Tuloksista havaittiin, että Kalman-suodattimen ulostulojen arvot pystyivät reagoimaan nopeammin mittauksissa esiintyviin muutoksiin verrattuna eksponentiaalisuodatukseen samalla kuitenkin suodattaen kohinaa pois mittauksista.

Lisäksi sinkkipiirin esivaahdotuksen kuva-analyysia sovellettiin sinkkimittausten kohentamiseen kertausvaahdotuskennossa.
Asennetun väri-CCD-kameran kaappaamien kuvien värianalyysituloksia käytettiin hyväksi lopullisen rikasteen pitoisuusmittausten parantamiseen.

Parantamisessa käytettiin apuna aliavaruusidentifiointimenetelmällä luotua Kalman-suodatinta.
Sen havaittiin toimivan varsin hyvin tilanteissa, joissa vallitsi hyvä korrelaatio punaisen värin intensiteetin ja röntgenfluoresenssianalysaattorin mittaamien tulosten välillä.
ED:2004-06-15
INSSI record number: 25319
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