Knut Kvaal

Dr. Knut Kvaal


Research Focus & Metrics

Academic Career Length

28Years (1999-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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DMDemmelash Mengistu
Demmelash Mengistu
VNVegard Nilsen
Vegard Nilsen
AHArve Heistad
Arve Heistad
KKKnut Kvaal
Knut Kvaal
Detection and quantification of tread wear particles in the environment have been a challenge owing to lack of a robust method. This study investigated the applicability of a combination of Simultaneous Thermal Analysis (STA), Fourier Transform Infra-Red (FTIR), and Parallel Factor Analysis (PARAFAC) in the detection and quantification of tire particles from formulated sediments. FTIR spectral data were obtained by heating 20 samples in STA. Among the 20 samples, 12 were tire granules in formulated sediments (TGIS) containing 1%, 2%, 5%, and 10% by mass of tire granules, while the remaining eight contained 0.5, 1, 2.5, and 5 mg of tire granules only (TGO). The PARAFAC models decomposed the trilinear data into three components. Tire rubber materials in tire granules (RM) and a combination of water and carbon dioxide were the components identified in all samples. The linear regression analysis of score values from the PARAFAC models showed that the RM quantity predicted were comparable to measured values in both TGIS and TGO. Decomposing the overlying components in the spectral data into different components, and predicting unknown quantity in both sample types, the method proves robust in identifying and quantifying tire particles from sediments.

19 February 2018 in Creativity and Innovation Management
Verified
Journal Article
Open access
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KCKasper Christensen
Kasper Christensen
JSJoachim Scholderer
Joachim Scholderer
SHStine Alm Hersleth
Stine Alm Hersleth
TNTormod Næs
Tormod Næs
KKKnut Kvaal
Knut Kvaal
EREinar Risvik
Einar Risvik
Online communities can be an attractive source of ideas for product and process innovations. However, innovative user‐contributed ideas may be few. From a perspective of harnessing “big data” for inbound open innovation, the detection of good ideas in online communities is a problem of detecting rare events. Recent advances in text analytics and machine learning have made it possible to screen vast amounts of online information and automatically detect user‐contributed ideas. However, it is still uncertain whether the ideas identified by such systems will also be regarded as sufficiently novel, feasible and valuable by firms who might decide to develop them further. A validation study is reported in which 200 posts from an online home brewing community were extracted by an automatic idea detection system. Two professionals from a brewing company evaluated the posts in terms of idea content, idea novelty, idea feasibility and idea value. The results suggest that the automatic idea detection system is sufficiently valid to be deployed for the harvesting and initial screening of ideas, and that the profile of the identified ideas (in terms of novelty, feasibility and value) follows the same pattern identified in studies of user ideation in general.

1 September 2003 in Food Hydrocolloids
Verified
Journal Article
Closed access
VSV.H Segtnan
V.H Segtnan
KKKnut Kvaal
Knut Kvaal
ERE.O Rukke
E.O Rukke
RSR.B Schüller
R.B Schüller
TIT Isaksson
T Isaksson

1 September 1999 in Scanning
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Journal Article
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BEBjørg Tordis Egelandsdal
Bjørg Tordis Egelandsdal
KCKirsti F. Christiansen
Kirsti F. Christiansen
VHVibeke Høst
Vibeke Høst
FLFrank Lundby
Frank Lundby
Jens WoldJens Wold
Jens Wold
KKKnut Kvaal
Knut Kvaal
Twelve dressing systems made by varying protein type, oil level, CaCl2, NaCl, and sucrose, were examined using scanning electron microscopy. Images from the 12 systems were quantitatively analysed using methods of feature extraction. These methods were based on vectorisations of the images followed by principal component analysis on the extracted vectors. These techniques were used to examine the reproducibility of the acquired images as well as to relate the images to rheologic and sensory texture parameters. Two feature extraction methods were used: the angle measure technique (AMT) and the absolute difference method (ABDF). The ABDF method used fewer principal components to extract information from images relevant to the complex modulus/sensory viscosity of the system, but the information seemed equally well preserved by the two‐feature extraction methods. The AMT was more efficient in classifying the images with respect to protein type. A fair correlation between images and complex modulus was obtained (R=0.73). It is suggested that a better correlation might be obtained by adding more systems, increasing the number of areas imaged for each system as well as avoiding systems of low viscosity.

20 July 2016 in Cogent Engineering
Verified
Journal Article
Open access
NSNataliia Sivchenko
Nataliia Sivchenko
KKKnut Kvaal
Knut Kvaal
Harsha RatnaweeraHarsha Ratnaweera
Harsha Ratnaweera
Flocs formation and growth are important characteristics in wastewater coagulation process. The shape and size of flocs highly affect further separation processes, therefore resulting treatment efficiency of wastewater after coagulation. Observed images of flocs tend to show strong relations to coagulation parameters: dose and coagulation time. In this article, three texture recognition techniques were evaluated for the ability to mathematically describe the relationship between the images of flocs and coagulant dosages. The easily computable texture analysis methods were found to be potential techniques for the characterization of the particles images. Ten out of eleven co-occurrence matrix-based grey level co-occurrence matrix (GLCM) texture features were found to be significant for the dosage prediction by a principal component regression model with only one principal component. Two features (Inverse difference moment and Variance) were selected for the multiple linear regression model. Test set prediction accuracy varied from 83 to 96% depending on texture analysis method and multivariate model. Best dosage prediction and image classification results were achieved by GLCM and angle measure technique. The results of image texture analysis coupled with multivariate modelling techniques indicate that it is possible to characterize and relate flocs images, captured during coagulation, with different coagulant dosages, as well as predict those dosages.

1 May 2017 in Water
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Journal Article
Open access
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GTGeir Torgersen
Geir Torgersen
JRJan Ketil Rød
Jan Ketil Rød
KKKnut Kvaal
Knut Kvaal
JBJarle T Bjerkholt
Jarle T Bjerkholt
OLOddvar Georg Lindholm
Oddvar Georg Lindholm
Urban flooding caused by heavy rainfall is expected to increase in the future. The main purpose of this study was to investigate the variables characterizing the placement of a house, which seem to have an impact when it comes to the exposure to floods. From the same region in Norway, data from 347 addresses were derived. All addresses were either associated with insurance claims caused by flooding or were randomly selected. A multivariate statistical model, Partial Least Square Regression (PLS), was used. Among others, the analysis has shown that the upstream, sealed area is the most significant variable for characterizing properties’ exposure to urban flooding. The model confirms that flooding tends to occur near old combined sewer mains and in concave curvature, and houses located in steep slopes seem to be less exposed. Using this method, it is possible to rank and quantify significant exposure variables contributing to urban floods within a region. Results from the PLS-analysis might provide important input to professionals, when planning and prioritizing measures. It can also predict flood-prone areas and make residents aware of the risks, which may induce them to implement preventive measures.