| 1. |
- Backlund, Sandra, 1986-, et al.
(författare)
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Energy efficiency potentials and energy management practices in Swedish firms
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In order to improve energy efficiency and reach the EU:s 20-20-20 primary energy saving target, focus has mainly been on diffusion of technology. Previous studies have illustrated large untapped energy saving potentials from implementing energy management practices in firms. Energy management practices have large effects on energy utilization and also a short pay-back time. According to these studies, energy management practices also effect investment decisions and the outcome of investments in energy efficient technologies. This paper investigates to what extent energy management practices influence firms estimation of energy efficiency potentials. Further it investigates two Swedish policy programs that promote industrial energy management practices: The Programme For improving Energy efficiency in energy-intensive industry (PFE) and the energy audit program and whether these have increased energy management practices in Swedish firms. A multiple case study has been conducted in order to investigate energy practices in firms in different industrial sectors. Employment of energy management varies between firms. The firms estimate equal energy efficiency potentials from implementation of energy efficient technology as for energy management practices. In total the firms estimate energy efficiency potentials of 12 %. The study shows that firms that have participated in the programs work more actively with energy management. This can be illustrated by the fact that 75 % of the firms that have not participated in any of the programs lack a person responsible for energy management and 50 % also lack a long term energy strategy. For firms that have participated in the programs the corresponding figures are 30 % and 33 %. The results indicate an untapped potential of energy efficiency measures that could be reached through increased energy management in Swedish industries.
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| 2. |
- Broberg, Patrik, 1983-, et al.
(författare)
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Analysis algorithm for surface crack detection by thermography with UV light excitation
- 2016
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Ingår i: Quantitative InfraRed Thermography 2016. - Gdańsk, Poland : Publishing Gdańsk University of Technology. ; , s. 160-165
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Konferensbidrag (refereegranskat)abstract
- Surface crack defects can be detected by IR thermograpgy due to the high absorption of energy within the crack cavity. It is often difficult to detect the defect in the raw data, since the signal easily drowns in the background. It is therefore important to have good analysis algorithms that can reduce the background and enhance the defect. Here an analysis algorithm is presented which significantly increases the signal to noise ratio of the defects and reduces the image sequence from the camera to one image.
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| 3. |
- Broberg, Patrik, 1983-
(författare)
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Analysis method for pulsed thermography based on an analytical solution of the heat equation
- 2014
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Tidskriftsartikel (refereegranskat)abstract
- An analytical solution to the heat equation is presented, using a simplified physical model of pulsed thermography. This solution was compared to experimental data and showed good correlation, with r=0.97. An analysis method for sizing and determining the depth of a defect was developed using this analytical solution. The shape of the defect was estimated using deconvolution. Results from thermography tests on flat bottom holes show the possibilities of the method to determine the size, shape and depth of the defect, if the physical properties of the material are known.
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| 4. |
- Broberg, Patrik, 1983-
(författare)
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Analytic model for pulsed thermography of subsurface defects
- 2014
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Ingår i: Archives QIRT 2014. - : QIRT. ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- An analytic solution to the heat equation is used to model the response of subsurface defects in pulsed thermography. The model is compared to measurement data and shows good agreement, both in spatial and temporaldomain. The capability of the model is then demonstrated by calculating the response of arbitrary defects at different depth. This model, even though simplified, can prove useful due to good accuracy and low computational time forcomparing analysis methods and for evaluating a thermography method on a new material or new type of defect.
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| 5. |
- Broberg, Patrik, 1983-, et al.
(författare)
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Comparison of NDT-methods for automatic inspection of weld defects
- 2015
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Ingår i: International journal of materials & product technology. - 0268-1900 .- 1741-5209. ; 50:1, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to investigate different NDT-methods for weld inspection in an objective manner. Test objects are produced with known variation of flaws: internal pores, surface and internal cracks, toe radius and weld depth. The NDT-methods compared are: phased array ultrasound, radiography, eddy current, thermography and shearography. The results show that radiography is the better method for volumetric defects in thin plates while ultrasound is better for flat defects and thicker, non-flat plates. Thermography was shown to have a good ability of detecting surface defects. A combination of ultrasound and thermography results in a detection of all the non-geometrical defects investigated in this study.
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| 6. |
- Broberg, Patrik, 1983-, et al.
(författare)
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Detection of Surface Cracks in Welds using Active Thermography
- 2012
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Ingår i: Proceedings18th World Conference on Non-Destructive Testing. - : South African Institute for Non-Destructive Testing (SAINT). - 9780620528726 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Surface cracks in welds can be detected using several non-destructive testing methods; among the more popular ones are eddy current, penetrant and magnetic particle testing. For an automatic inspection cell, the traditional techniques have limitations. Here we have investigated the possibility of using active thermography for detecting surface cracks in welds. This technique features advantages such as non-contact and high speed. The weld is illuminated using an infrared light source. Due to higher energy absorption in a surface crack, the defect will be identified as a hot spot when imaged by an infrared camera. Artificial weld defects (notches) are investigated by use of active thermography. Results from an inspection of real longitudinal cold cracks in a weld are also presented. The results show that active thermography looks promising for detection of even small cracks and notches, as long as they are open to the surface.
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| 7. |
- Broberg, Patrik, 1983-
(författare)
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Evaluation of a method to radiometric calibrate hot target image data by using simple reference sources close to ambient temperatures
- 2010
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Ingår i: Infrared Imaging Systems. - : SPIE. - 9780819481269
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To perform radiometric calibrations of image data, reference sources are needed in order to acquire data at two or more radiance levels giving the calibration parameters. Due to sensor drift for detectors in the infrared region the parameters have to be frequently recalculated during an extended signature measurement if the accuracy is to be maintained. In signature measurements where the incident radiance levels from hot targets are exceeding the background by many orders of magnitude the reference sources need to emit radiation at high radiance levels. Such reference sources are more complex and so is the handling of these sources. The calibration procedure tends to become impractical in field trials where several spectral bands are involved, which increases the need for reference data and the number of reference sources. A method to radiometric calibrate hotspot target data by using only a few simple reference sources close to ambient temperatures has been evaluated in this paper. Reference data has been collected both in laboratory studies and in field trials at various weather conditions. The accuracy and the precision of the method are presented. The uncertainty due to sensor drift is estimated. Error sources connected to the calibration method are discussed.
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| 8. |
- Broberg, Patrik, 1983-
(författare)
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Imaging and analysis methods for automated weld inspection
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- All welding processes can give rise to defects, which weakens the joint and can eventually lead to the failure of the welded structure. In order to inspect welds for detects, without affecting the usability of the product, non-destructive testing (NDT) is needed. NDT includes a wide range of different techniques, based on different physical principles, each with its advantages and disadvantages. The testing is often performed manually by a skilled operator and in many cases only as spot-checks. Today the trend in industry is to move towards thinner material, in order to save weight for cost and for environmental reasons. The need for inspection of a larger portion of welds therefore increases and there is an increasing demand for fully automated inspection, including both the mechanised testing and the automatic analysis of the result. Compared to manual inspection, an automated solution has advantages when it comes to speed, cost and reliability. A comparison of several NDT methods was therefore first performed in order to determine which methods have most potential for automated weld inspection. Automated analysis of NDT data poses several difficulties compared to manual data evaluation. It is often possible for an operator to detect defects even in noisy data, through experience and knowledge about the part being tested. Automatic analysis algorithms on the other hand suffer greatly from both random noise as well as indications that originate from geometrical variations. The solution to this problem is not always obvious. Some NDT techniques might not be suitable for automated inspection and will have to be replaced by other, better adapted methods. One such method that has been developed during this work is thermography for the detection of surface cracks. This technique offers several advantages, in terms of automation, compared to existing methods. Some techniques on the other hand cannot be easily replaced. Here the focus is instead to prepare the data for automated analysis, using various pre-processing algorithms, in order to reduce noise and remove indications from sources other than defects. One such method is ultrasonic testing, which has a good ability for detecting internal defects but suffers from noisy signals with low spatial resolution. Work was here done in order to separate indications from corners from other indications. This can also help to improve positioning of the data and thereby classification of defects. The problem of low resolution was handled by using a deconvolution algorithm in order to reduce the effect of the spread of the beam.The next step in an automated analysis system is to go beyond just detection and start characterising defects. Using knowledge of the physical principles behind the NDT method in question and how the properties of a defect affect the measurement, it is sometimes possible to develop methods for determining properties such as the size and shape of a defect. This kind of characterisation of a defect is often difficult to do in the raw data, and is therefore an area where automated analysis can go beyond what is possible for an operator during manual inspection. This was shown for flash thermography, where an analysis method was developed that could determine the size, shape and depth of a defect. Similarly for laser ultrasound, a method was developed for determining the size of a defect.
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| 9. |
- Broberg, Patrik, 1983-, et al.
(författare)
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Improved Corner Detection by Ultrasonic Testing using Phase Analysis
- 2013
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Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 53:2, s. 630-634
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Tidskriftsartikel (refereegranskat)abstract
- In ultrasonic testing, corners are used for sensitivity calibration in the form of notches, for measuring the sound velocity in the material, and as known reference points during testing. A 90° corner will always reflect incoming waves in the opposite direction due to a double reflection and therefore give a strong echo. This article presents a method for separating the echo from a corner from other echoes and more accurately find the position of the corner. The method is based on analysing the phase of the reflected signal. The proposed method was tested on a steel calibration block and the width of the indication was reduced by up to 50% compared to the amplitude signal. This results in a more accurate positioning of the corner. Using the phase instead of the amplitude will also improve the reliability, since reflections other than from corners will disappear.
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| 10. |
- Broberg, Patrik, 1983-, et al.
(författare)
-
Improved Image Quality in Phased Array Ultrasound by Deconvolution
- 2012
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Ingår i: Proceedings18th World Conference on Non-Destructive Testing. - : South African Institute for Non-Destructive Testing (SAINT). - 9780620528726 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- High contrast and resolution in phased array ultrasonic images are of importance for accurate evaluation. The spread of the ultrasonic beam is one cause of the images being unsharp. One technique for reducing the influence of the beam spread, and thereby improving the image quality, is by deconvolving the data with the point spread function of the ultrasonic beam. By assuming that the material is homogeneous, the point spread function of the beam can be simulated using diffraction theory. Results from a deconvolution performed on data acquired from a side drilled hole in a steel calibration block are presented. It is shown that a significant improvement in sharpness and contrast can be achieved.
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