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Publikasjoner (10 av 156) Visa alla publikasjoner
Wahl, J., Sjödahl, M. & Ramser, K. (2020). Single-Step Preprocessing of Raman Spectra using Convolutional Neural Networks. Applied Spectroscopy
Åpne denne publikasjonen i ny fane eller vindu >>Single-Step Preprocessing of Raman Spectra using Convolutional Neural Networks
2020 (engelsk)Inngår i: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530, ISSN 0003-7028Artikkel i tidsskrift (Fagfellevurdert) Epub ahead of print
Abstract [en]

Preprocessing of Raman spectra is generally done in three separate steps: (1) cosmic ray removal, (2) signal smoothing, and(3) baseline subtraction. We show that a convolutional neural network (CNN) can be trained using simulated data tohandle all steps in one operation. First, synthetic spectra are created by randomly adding peaks, baseline, mixing of peaksand baseline with background noise, and cosmic rays. Second, a CNN is trained on synthetic spectra and known peaks.The results from preprocessing were generally of higher quality than what was achieved using a reference based onstandardized methods (second-difference, asymmetric least squares, cross-validation). From 105 simulated observations,91.4% predictions had smaller absolute error (RMSE), 90.3% had improved quality (SSIM), and 94.5% had reduced signal-tonoise(SNR) power. The CNN preprocessing generated reliable results on measured Raman spectra from polyethylene,paraffin and ethanol with background contamination from polystyrene. The result shows a promising proof of concept forthe automated preprocessing of Raman spectra.

sted, utgiver, år, opplag, sider
Sage Publications, 2020
Emneord
Raman spectroscopy, convolutional neural network, CNN, preprocessing, simulated data, chemometrics
HSV kategori
Forskningsprogram
Experimentell mekanik
Identifikatorer
urn:nbn:se:ltu:diva-77138 (URN)10.1177/0003702819888949 (DOI)
Forskningsfinansiär
Swedish Foundation for Strategic Research , ITM17-0056Swedish Research Council, 2016-04220
Tilgjengelig fra: 2019-12-11 Laget: 2019-12-11 Sist oppdatert: 2020-02-21
Dittes, N., Sjödahl, M., Pettersson, A. & Lang, D. (2019). Automated Dielectric Thermoscopy Characterization of Water Contaminated Grease. Tribology Transactions, 62(5), 859-867
Åpne denne publikasjonen i ny fane eller vindu >>Automated Dielectric Thermoscopy Characterization of Water Contaminated Grease
2019 (engelsk)Inngår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 62, nr 5, s. 859-867Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Machine maintenance is important for improving machine uptime, reliability, and reducing costs. Grease is used in most rolling element bearings, and one common failure criterion is water contamination, so developing a sensor which can detect water content automatically without human input could be a useful endeavor. The temperature dependence on the dielectric properties of water-contaminated grease is investigated in this paper with computer logged instrumentation. This method has been termed Dielectric Thermoscopy (DT). Several off the shelf (two lithium, one lithium complex, and two calcium sulphonate complex) and one unadditivized lithium grease are tested with varying amounts of water contamination from 0% to approximately 5%. Another grease is tested with small increments of added water from 0% to 0.97% to test the resolution of the measurement. The purpose is to use the capacitance temperature slope (termed dielectric thermoscopy) to show correlations to the water content of the grease sample and investigate if any grease types will pose problems in the measurement. A small, custom made fringe field capacitance sensor with an integrated temperature sensor has been used for this characterization and data is logged automatically with laboratory equipment and a PC. A useable and positive correlation to water content and the DT measurement of roughly 0.5 pF per 10 °C and percentage of water is found, although it was found that some greases have different behavior than others.

sted, utgiver, år, opplag, sider
Taylor & Francis, 2019
HSV kategori
Forskningsprogram
Maskinelement; Experimentell mekanik
Identifikatorer
urn:nbn:se:ltu:diva-75141 (URN)10.1080/10402004.2019.1629051 (DOI)000479625300001 ()2-s2.0-85073653107 (Scopus ID)
Merknad

Validerad;2019;Nivå 2;2019-08-22 (johcin)

Tilgjengelig fra: 2019-06-28 Laget: 2019-06-28 Sist oppdatert: 2019-11-04bibliografisk kontrollert
Sjödahl, M. (2019). Gradient Correlation Functions in Digital Image Correlation. Applied Sciences, 9(10), Article ID 2127.
Åpne denne publikasjonen i ny fane eller vindu >>Gradient Correlation Functions in Digital Image Correlation
2019 (engelsk)Inngår i: Applied Sciences, E-ISSN 2076-3417, Vol. 9, nr 10, artikkel-id 2127Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The performance of seven different correlation functions applied in Digital Image Correlation has been investigated using simulated and experimentally acquired laser speckle patterns. The correlation functions were constructed as combinations of the pure intensity correlation function, the gradient correlation function and the Hessian correlation function, respectively. It was found that the correlation function that was constructed as the product of all three pure correlation functions performed best for the small speckle sizes and large correlation values, respectively. The difference between the different functions disappeared as the speckle size increased and the correlation value dropped. On average, the random error of the combined correlation function was half that of the traditional intensity correlation function within the optimum region.

sted, utgiver, år, opplag, sider
MDPI, 2019
Emneord
image correlation, gradient correlation functions, laser speckles
HSV kategori
Forskningsprogram
Experimentell mekanik
Identifikatorer
urn:nbn:se:ltu:diva-75069 (URN)10.3390/app9102127 (DOI)000473748100162 ()2-s2.0-85066461522 (Scopus ID)
Merknad

Validerad;2019;Nivå 2;2019-06-27 (johcin)

Tilgjengelig fra: 2019-06-27 Laget: 2019-06-27 Sist oppdatert: 2019-08-16bibliografisk kontrollert
Öhman, J., Sjödahl, M. & Gren, P. (2019). Polarization Resolved Dual-View Holographic System for Investigation of Microparticles. In: OSA Technical Digest (Optical Society of America, 2019): . Paper presented at Digital Holography and Three-Dimensional Imaging 2019. , Article ID Th2A.5.
Åpne denne publikasjonen i ny fane eller vindu >>Polarization Resolved Dual-View Holographic System for Investigation of Microparticles
2019 (engelsk)Inngår i: OSA Technical Digest (Optical Society of America, 2019), 2019, artikkel-id Th2A.5Konferansepaper, Oral presentation with published abstract (Fagfellevurdert)
Abstract [en]

A dual-view polarization resolved digital-holographic system is presented. The necessary calibration for both polarization and spatial coordinates are outlined. As an example the system is is used to track spherical microparticles in a cuvette.

HSV kategori
Forskningsprogram
Experimentell mekanik
Identifikatorer
urn:nbn:se:ltu:diva-76066 (URN)10.1364/DH.2019.Th2A.5 (DOI)
Konferanse
Digital Holography and Three-Dimensional Imaging 2019
Tilgjengelig fra: 2019-09-19 Laget: 2019-09-19 Sist oppdatert: 2019-10-22
Öhman, J., Gren, P. & Sjödahl, M. (2019). Polarization-resolved dual-view holographic system for 3D inspection of scattering particles. Paper presented at OSA Topical Meeting on Digital Holography and 3D Imaging (DH), 20–23 May 2019, Bordeaux, France.. Applied Optics, 58(34), G31-G40
Åpne denne publikasjonen i ny fane eller vindu >>Polarization-resolved dual-view holographic system for 3D inspection of scattering particles
2019 (engelsk)Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 58, nr 34, s. G31-G40Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

A novel dual-view polarization-resolved pulsed holographic system for particle measurements is presented. Both dual-view configuration and polarization-resolved registration are well suited for particle holography. Dual-view registration improves the accuracy in the detection of 3D position and velocities, and polarization-resolved registration provides polarization information about individual particles. The necessary calibrations are presented, and aberrations are compensated for by mapping the positions in the two views to positions in a global coordinate system. The system is demonstrated on a sample consisting of 7 μm spherical polystyrene particles dissolved in water in a cuvette. The system is tested with different polarizations of the illumination. It is found that the dual view improves the accuracy significantly in particle tracking. It is also found that by having polarization-resolved holograms, it is possible to separate naturally occurring sub-micrometer particles from the larger, 7 μm seeding particles.

sted, utgiver, år, opplag, sider
The Optical Society, 2019
HSV kategori
Forskningsprogram
Experimentell mekanik
Identifikatorer
urn:nbn:se:ltu:diva-76067 (URN)10.1364/AO.58.000G31 (DOI)000502062900007 ()2-s2.0-85075624742 (Scopus ID)
Konferanse
OSA Topical Meeting on Digital Holography and 3D Imaging (DH), 20–23 May 2019, Bordeaux, France.
Forskningsfinansiär
Swedish Research Council, 621-2014-4906
Merknad

Konferensartikel i tidskrift

Tilgjengelig fra: 2019-09-19 Laget: 2019-09-19 Sist oppdatert: 2020-02-25bibliografisk kontrollert
Lindström, J., Lejon, E., Kyösti, P., Mecella, M., Heutelbeck, D., Hemmje, M., . . . Gunnarsson, B. (2019). Towards intelligent and sustainable production systems with a zero-defect manufacturing approach in an Industry4.0 context. In: Edited by Peter Butala, Edvard Govekar, Rok Vrabič (Ed.), Procedia CIRP, vol 81: . Paper presented at 52nd CIRP Conference on Manufacturing Systems (CMS), Ljubljana, Slovenia, June 12-14, 2019 (pp. 880-885). Elsevier, 81
Åpne denne publikasjonen i ny fane eller vindu >>Towards intelligent and sustainable production systems with a zero-defect manufacturing approach in an Industry4.0 context
Vise andre…
2019 (engelsk)Inngår i: Procedia CIRP, vol 81 / [ed] Edited by Peter Butala, Edvard Govekar, Rok Vrabič, Elsevier, 2019, Vol. 81, s. 880-885Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

The paper addresses intelligent and sustainable production achieved through combination and integration of online predictive maintenance, monitoring of process parameters and continuous quality control of both input materials and output from the process. This enables production systems, within both manufacturing and process industries, to move towards zero-defect manufacturing. Such a zero-defect manufacturing approach allows for earlier identification of problems or issues, which will or already negatively affect the output. The paper outlines the first part of the second cycle of an action research effort at Gestamp HardTech AB in Sweden, whose objective is to keep its position as a world-leading provider of press-hardened vehicle parts. In order to fully implement the zero-defect manufacturing approach, 4-6 action research cycles are expected to be needed in order to iteratively refine the approach. During the first cycle, various methods and solutions for some of the individual issues/problems have been conceptualized, realized and initially tested. The selected design criteria for the action research efforts were: simplicity, low cost, robustness, high-quality output and future-proofing. The result from the research in the second cycle so far is an action plan for the technical change and a set of challenges/problems which need additional investigation.

sted, utgiver, år, opplag, sider
Elsevier, 2019
Serie
Procedia CIRP, vol 81, ISSN 2212-8271
Emneord
continuous quality controlI, Industry4.0, intelligent, online predictive maintenance, production, sustainable, zero-defect manufacturing
HSV kategori
Forskningsprogram
Informationssystem; Experimentell mekanik; Reglerteknik
Identifikatorer
urn:nbn:se:ltu:diva-75114 (URN)10.1016/j.procir.2019.03.218 (DOI)
Konferanse
52nd CIRP Conference on Manufacturing Systems (CMS), Ljubljana, Slovenia, June 12-14, 2019
Tilgjengelig fra: 2019-06-28 Laget: 2019-06-28 Sist oppdatert: 2019-07-08bibliografisk kontrollert
Wahl, J., Gren, P., Bergström, P., Lindbäck, T., Magnusson, M., Domeij, K. & Sjödahl, M. (2018). Comparison between process simulation and deformation measured by defocused speckle photography. In: M. Kujawińska ; L. R. Jaroszewicz (Ed.), Speckle 2018: VII International Conference On Speckle Metrology. Paper presented at SPECKLE 2018: VII International Conference on Speckle Metrology, 9-12 September 2018, Janów Podlaski, Poland.. SPIE - International Society for Optical Engineering, 10834, Article ID 108341K.
Åpne denne publikasjonen i ny fane eller vindu >>Comparison between process simulation and deformation measured by defocused speckle photography
Vise andre…
2018 (engelsk)Inngår i: Speckle 2018: VII International Conference On Speckle Metrology / [ed] M. Kujawińska ; L. R. Jaroszewicz, SPIE - International Society for Optical Engineering, 2018, Vol. 10834, artikkel-id 108341KKonferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Defocused laser speckle photography is used as a tool to measure the heat responses in a titanium component during laser heating. The evolution of the response is compared with a set of preprocessed Finite Element Simulations of the corresponding process with the aim to verify the simulation model and to find the simulation settings that best resemble the experimental results. The titanium component consists of a 300 x 100 mm2 substrate of thickness 3.2 mm on which a 200 x 30 x 11 mm3 ridge is built up using the laser metal deposition by wire process. The component is heated on the top of the ridge by a 300 W laser for 10 s and the deformation of the subtrate is followed throughout the heating-cooling cycle. The simulated deformation gradient is shown to resemble the measured response, and the magnitude of the response indicates that about 70 % of the laser power transferres into heat in the metal.

sted, utgiver, år, opplag, sider
SPIE - International Society for Optical Engineering, 2018
Serie
Proceedings of SPIE - the International Society for Optical Engineering, ISSN 0277-786X ; 10834
Emneord
Laser speckle, deformation, in-process measurement
HSV kategori
Forskningsprogram
Experimentell mekanik; Datorstödd maskinkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-71895 (URN)10.1117/12.2319384 (DOI)000455052600052 ()2-s2.0-85058383509 (Scopus ID)9781510622975 (ISBN)
Konferanse
SPECKLE 2018: VII International Conference on Speckle Metrology, 9-12 September 2018, Janów Podlaski, Poland.
Forskningsfinansiär
VINNOVA
Tilgjengelig fra: 2018-12-05 Laget: 2018-12-05 Sist oppdatert: 2019-12-11bibliografisk kontrollert
Amer, E., Gren, P., Ramser, K. & Sjödahl, M. (2018). Measurement of selective species concentration using spectroscopic holography. In: M. Kujawińska ; L. R. Jaroszewicz (Ed.), Speckle 2018: VII International Conference on Speckle Metrology. Paper presented at Speckle 2018: VII International Conference On Speckle Metrology 9-12 September 2018 Janów Podlaski, Poland. SPIE - International Society for Optical Engineering, 10834, Article ID 108340P.
Åpne denne publikasjonen i ny fane eller vindu >>Measurement of selective species concentration using spectroscopic holography
2018 (engelsk)Inngår i: Speckle 2018: VII International Conference on Speckle Metrology / [ed] M. Kujawińska ; L. R. Jaroszewicz, SPIE - International Society for Optical Engineering, 2018, Vol. 10834, artikkel-id 108340PKonferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Spectroscopic holography refers to techniques in which the detected hologram contains information about specific species in the medium under study. In general, at least two lasers are required with wavelengths chosen carefully to fit the interaction process utilized. In this process, energy from the shorter wavelength laser beam is transferred to the longer wavelength coherently through the process of stimulated emission. Two interaction mechanisms are considered; Stimulated Laser Induced Fluorescence (LIF) and Stimulated Raman Scattering (SRS), which both are species specific with the ability of coherent interaction. In this paper, the fundamental properties of spectroscopic holography is presented and demonstrated with a few idealized experiments. These validation experiments are performed in a gas chamber in which different gases may be blended and the gas pressure changed between 1-12 bars. In addition, two examples of applications are presented. In the first set of experiments, LIF holography is used to image light absorption and laser heating in a dye simultaneously. The second set of experiments is performed in a ow of methane gas. It is demonstrated that the combination of holographic phase measurements and SRS gain images may be used for calibration. This calibration may further be used to measure absolute concentration in a burning flame.

sted, utgiver, år, opplag, sider
SPIE - International Society for Optical Engineering, 2018
Serie
Proceedings of SPIE - the International Society for Optical Engineering, ISSN 0277-786X ; 10834
HSV kategori
Forskningsprogram
Experimentell mekanik
Identifikatorer
urn:nbn:se:ltu:diva-72430 (URN)10.1117/12.2319386 (DOI)000455052600021 ()2-s2.0-85058412906 (Scopus ID)9781510622975 (ISBN)
Konferanse
Speckle 2018: VII International Conference On Speckle Metrology 9-12 September 2018 Janów Podlaski, Poland
Tilgjengelig fra: 2019-01-03 Laget: 2019-01-03 Sist oppdatert: 2019-01-28bibliografisk kontrollert
Dittes, N., Pettersson, A., Sjödahl, M., Casselgren, J., Marklund, P. & Lugt, P. M. (2018). Optical Attenuation Characterization of Water Contaminated Lubricating Grease. Tribology Transactions, 61(4), 726-732
Åpne denne publikasjonen i ny fane eller vindu >>Optical Attenuation Characterization of Water Contaminated Lubricating Grease
Vise andre…
2018 (engelsk)Inngår i: Tribology Transactions, ISSN 1040-2004, E-ISSN 1547-397X, Vol. 61, nr 4, s. 726-732Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Water-contaminated grease samples are investigated with attenuation spectra in the visible and near-infrared (NIR) regions in this article. The purpose of this investigation was to identify a model with optical attenuation spectra such that the water content of grease samples could be characterized with a simple measurement setup using common methodology from the field of instrumental chemistry. The ratio between two chosen wavelengths of light appears to approximate the water content of grease samples with an acceptable coefficient of determination using a methodology to show what can potentially be done to develop condition monitoring tools. To illustrate the outlined method, a prestudy of grease aging and oxidation levels is also investigated to show that other variables do not significantly change the measurement.

sted, utgiver, år, opplag, sider
Taylor & Francis, 2018
HSV kategori
Forskningsprogram
Maskinelement; Experimentell mekanik
Identifikatorer
urn:nbn:se:ltu:diva-67205 (URN)10.1080/10402004.2017.1404175 (DOI)000438157400015 ()2-s2.0-85044094152 (Scopus ID)
Merknad

Validerad;2018;Nivå 2;2018-08-09 (rokbeg)

Tilgjengelig fra: 2018-01-09 Laget: 2018-01-09 Sist oppdatert: 2019-09-14bibliografisk kontrollert
Sjödahl, M. & Amer, E. (2018). Quantitative measurement of thin phase objects: comparison of speckle deflectometry and defocus-variant lateral shear interferometry. Applied Optics, 57(14), 3645-3652
Åpne denne publikasjonen i ny fane eller vindu >>Quantitative measurement of thin phase objects: comparison of speckle deflectometry and defocus-variant lateral shear interferometry
2018 (engelsk)Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 57, nr 14, s. 3645-3652Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The two techniques of lateral shear interferometry and speckle deflectometry are analyzed in a common optical system for their ability to measure phase gradient fields of a thin phase object. The optical system is designed to introduce a shear in the frequency domain of a telecentric imaging system that gives a sensitivity of both techniques in proportion to the defocus introduced. In this implementation, both techniques successfully measure the horizontal component of the phase gradient field. The response of both techniques scales linearly with the defocus distance, and the precision is comparative, with a random error in the order of a few rad/mm. It is further concluded that the precision of the two techniques relates to the transverse speckle size in opposite ways. While a large spatial coherence width, and correspondingly a large lateral speckle size, makes lateral shear interferometry less susceptible to defocus, a large lateral speckle size is detrimental for speckle correlation. The susceptibility for the magnitude of the defocus is larger for the lateral shear interferometry technique as compared to the speckle deflectometry technique. The two techniques provide the same type of information; however, there are a few fundamental differences. Lateral shear interferometry relies on a special hardware configuration in which the shear angle is intrinsically integrated into the system. The design of a system sensitive to both in-plane phase gradient components requires a more complex configuration and is not considered in this paper. Speckle deflectometry, on the other hand, requires no special hardware, and both components of the phase gradient field are given directly from the measured speckle deformation field.

sted, utgiver, år, opplag, sider
Optical Society of America, 2018
HSV kategori
Forskningsprogram
Strömningslära
Identifikatorer
urn:nbn:se:ltu:diva-68878 (URN)10.1364/AO.57.003645 (DOI)000431880000003 ()2-s2.0-85046971352 (Scopus ID)
Merknad

Validerad;2018;Nivå 2;2018-05-24 (andbra)

Tilgjengelig fra: 2018-05-24 Laget: 2018-05-24 Sist oppdatert: 2018-08-21bibliografisk kontrollert
Organisasjoner
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0003-4879-8261