| 1. |
- Albertsson-Wikland, Kerstin, 1947, et al.
(författare)
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Growth hormone dose-dependent pubertal growth : a randomized trial in short children with low growth hormone secretion
- 2014
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Ingår i: Hormone Research in Paediatrics. - : S. Karger AG. - 1663-2818 .- 1663-2826. ; 82:3, s. 158-170
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Growth hormone (GH) treatment regimens do not account for the pubertal increase in endogenous GH secretion. This study assessed whether increasing the GH dose and/or frequency of administration improves pubertal height gain and adult height (AH) in children with low GH secretion during stimulation tests, i. e. idiopathic isolated GH deficiency.Methods: A multicenter, randomized, clinical trial (No. 88-177) followed 111 children (96 boys) at study start from onset of puberty to AH who had received GH(33) mu g/kg/day for >= 1 year. They were randomized to receive 67 mu g/kg/day (GH(67)) given as one (GH(67x1); n = 35) or two daily injections (GH(33x2); n = 36), or to remain on a single 33 mu g/kg/day dose (GH(33x1); n = 40). Growth was assessed as height SDS gain for prepubertal, pubertal and total periods, as well as AH SDS versus the population and the midparental height.Results: Pubertal height SDS gain was greater for patients receiving a high dose (GH(67), 0.73) than a low dose (GH(33x1), 0.41, p < 0.05). AH(SDS) was greater on GH(67) (GH(67x1), -0.84; GH(33x2), -0.83) than GH(33) (-1.25, p < 0.05), and height SDS gain was greater on GH(67) than GH(33) (2.04 and 1.56, respectively; p < 0.01). All groups reached their target height SDS.Conclusion: Pubertal height SDS gain and AH SDS were dose dependent, with greater growth being observed for the GH(67) than the GH(33) randomization group; however, there were no differences between the once-and twice-daily GH(67) regimens. (C) 2014 S. Karger AG, Basel.
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| 2. |
- de Vries, Charlotte, et al.
(författare)
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Antibodies to Porphyromonas gingivalis Are Increased in Patients with Severe Periodontitis, and Associate with Presence of Specific Autoantibodies and Myocardial Infarction
- 2022
-
Ingår i: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- There is accumulating data suggesting that periodontitis is associated with increased risk of systemic and autoimmune diseases, including cardiovascular disease, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and there is an unmet need to identify these individuals early. With the periodontal bacteria Porphyromonas gingivalis (Pg) as one of the key drivers of periodontitis, we set out to investigate whether antibodies to Pg virulence factor arginine gingipain (Rgp) could serve as a biomarker for periodontitis patients at increased risk of autoimmunity and systemic disease. We measured serum anti-Rgp IgG in three study populations: PAROKRANK (779 individuals with myocardial infarction (MI); 719 controls), where 557 had periodontitis, and 312 were positive for autoantibodies associated with RA/SLE; the PerioGene North pilot (41 periodontitis; 39 controls); and an SLE case/control study (101 SLE; 100 controls). Anti-Rgp IgG levels were increased in severe periodontitis compared to controls (p < 0.0001), in individuals positive for anti-citrullinated protein antibodies (p = 0.04) and anti-dsDNA antibodies (p = 0.035), compared to autoantibody-negative individuals; and in MI patients versus matched controls (p = 0.035). Our data support longitudinal studies addressing the role of anti-Rgp antibodies as biomarkers for periodontitis patients at increased risk of developing autoimmunity linked to RA and SLE, and mechanisms underpinning these associations.
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| 3. |
- Froitzheim, Jan, 1981, et al.
(författare)
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Nano coated interconnects for SOFC (NaCoSOFC)
- 2013
-
Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; 57:1, s. 2187-2193
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Konferensbidrag (refereegranskat)abstract
- The NaCoSOFC project is focused on the development of nano coatings for SOFC interconnects. The project is sponsored by the Nordic Top Level Research Initiative and has four project partners: Sandvik Materials Technology which is producing coated interconnects, Chalmers University of Technology and the University of Oslo that characterize samples with respect to e.g. corrosion, Cr evaporation and ASR as well as Topsoe Fuel Cell that is testing the developed interconnects in its stacks. The developed coatings are based on a combination of Co with RE elements and exhibit high corrosion resistance, 10 fold decrease in Cr evaporation and ASR values that are approximately 50% of the uncoated material.
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| 4. |
- Goebel, Claudia, 1988, et al.
(författare)
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Long term (4 years) performance of Co/Ce coated 441 for SOFC interconnect applications
- 2017
-
Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; 78:1, s. 1675-1679
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Konferensbidrag (refereegranskat)abstract
- Co/Ce coated 441 samples were exposed at 800°C in laboratory air for up to 37 000 h and subsequently characterized using different techniques. Mass gain data of all samples were recorded throughout exposure. Cr-evaporation measurements were conducted and compared with unexposed Co/Ce coated AISI 441 as well as unexposed and uncoated AISI 441. Furthermore SEM analysis on BIB cross-sections was performed on 7 000 h, 23 000 h and 35 000 h exposed Co/Ce coated 441.
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| 5. |
- Hedner, Jan A, 1953, et al.
(författare)
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Effects of TRH and TRH analogues on the central regulation of breathing in the rat.
- 1983
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Ingår i: Acta physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 117:3, s. 427-37
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Tidskriftsartikel (refereegranskat)abstract
- Respiratory activity was studied in rats during light halothane anesthesia. Thyrotropin releasing hormone (TRH) and two TRH analogues: the desamidated form (TRH-OH) and gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate (DN 1417) were administered intracerebroventricularly. TRH 0.5-5 micrograms induced a marked tachypnoea with a rapid onset and a duration of at least 20 min. DN 1417, a potent analogue of TRH with a very low TSH (thyroid stimulating hormone) releasing activity was more effective in stimulating respiratory frequency, while TRH-OH, regarded to have neither TSH releasing nor extra hypothalamic effects, at equimolar doses was unable to induce any changes in the respiratory pattern. When TRH was given into the fourth ventricle the dose response curve was slightly shifted to the left. In experiments employing the occluded breath technique, P0.1 was increased in the same magnitude as the mean inspiratory flow (VT/T1). The results also indicated an increase in the gain of the inflation reflex loop whereas the central bulbopontine setting for T1 and TTOT were not significantly changed. Local injection of TRH into the nucleus tractus solitarii induced a stimulation of respiratory frequency which was slower in onset compared to the response seen after injection into the lateral or fourth ventricles. Concomitantly to the respiratory changes, i.c.v. TRH injection induced a hypocarbia and an alkalosis. No changes in blood pressure or heart rate were seen. The respiratory stimulant effect of TRH could be potentiated by pretreatment with naloxone, methylatropine or a low dose of GABA. Haloperidol or propranolol did not significantly change the respiratory effects of TRH, while reserpine pretreatment seemed to blunt some of the ventilatory effects of TRH. It seems likely that TRH has few direct effects on brain stem neurones involved in the central regulation of respiration, but the main effects seem to be elicited in areas rostral to the brain stem. The respiratory stimulating effect of TRH is unrelated to TSH. Furthermore, other neurotransmitter systems might also be involved in modulation of the respiratory stimulation evoked by TRH.
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| 6. |
- Lundberg, Jan, et al.
(författare)
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High-speed video photographs of lubrication breakdown in squeeze-sliding contact
- 1992
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Ingår i: Wear. - 0043-1648 .- 1873-2577. ; 157:2, s. 427-433
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Tidskriftsartikel (refereegranskat)abstract
- Using photographs from a high-speed video camera it was confirmed that the main part of breakdown of a lubricating film will appear at the end of the contact time for a contact simultaneously subjected to squeeze and sliding motion. This corresponds with earlier findings using totally different equipment for electric detection of the asperity contact. The present investigation used glass and steel as the lubricated surfaces, instead of steel and steel as was the case in the earlier investigation. In combination with far less stiff equipment, the new materials gave longer contact time and larger elastic deformations of the contact bodies. It was also verified that increased surface roughness, increased sliding velocity and decreased viscosity increase the risk of oil film breakdown
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| 7. |
- Lundberg, Rebecca, et al.
(författare)
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Perinatal exposure to PCB 153, but not PCB 126, alters bone tissue composition in female goat offspring
- 2006
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Ingår i: Toxicology. - : Elsevier BV. - 0300-483X .- 1879-3185. ; 228:1, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate if environmentally relevant doses of the putative estrogenic non dioxin-like PCB 153 and the dioxin-like PCB 126 caused changes in bone tissue in female goat offspring following perinatal exposure. Goat dams were orally dosed with PCB 153 in corn oil (98 microg/kg body wt/day) or PCB 126 (49 ng/kg body wt/day) from day 60 of gestation until delivery. The offspring were exposed to PCB in utero and through mother's milk. The suckling period lasted for 6 weeks. Offspring metacarpal bones were analysed using peripheral quantitative computed tomography (pQCT) after euthanisation at 9 months of age. The diaphyseal bone was analysed at a distance of 18% and 50% of the total bone length, and the metaphyseal bone at a distance of 9%. Also, biomechanical three-point bending of the bones was conducted, with the load being applied to the mid-diaphyseal pQCT measure point (50%). PCB 153 exposure significantly decreased the total cross-sectional area (125 mm(2)+/-4) versus non-exposed (142 mm(2)+/-5), decreased the marrow cavity (38 mm(2)+/-4) versus non-exposed (50 mm(2)+/-3) and decreased the moment of resistance (318 mm(3)+/-10) versus non-exposed (371 mm(3)+/-20) at the diaphyseal 18% measure point. At the metaphyseal measure point, the trabecular bone mineral density (121 mg/cm(3)+/-5) was increased versus non-exposed (111 mg/cm(3)+/-3). PCB 126 exposure did not produce any observable changes in bone tissue. The biomechanical testing of the bones did not show any significant changes in bone strength after PCB 153 or PCB 126 exposure. In conclusion, perinatal exposure to PCB 153, but not PCB 126, resulted in altered bone composition in female goat offspring.
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| 8. |
- Nykänen, Arne, et al.
(författare)
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Modelling perceptual dimensions of saxophone sounds
- 2009
-
Ingår i: Acta Acoustica united with Acustica. - 1610-1928 .- 1861-9959. ; 95:3, s. 539-549
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Tidskriftsartikel (refereegranskat)abstract
- In the past, musical instruments were developed over long periods of time by skilled craftsmen. Today, most instruments are mass-produced. Design of musical instruments as mass-produced products requires using strategies which make it easier to identify customer needs and develop exact specifications. To develop useful specifications it is necessary to convert general descriptions into something which can be commonly understood and also be interpretable in terms of acoustic metrics. In this study, methods for analysis and specification of steady state parts of alto saxophone sounds were developed. Saxophonists' use of verbal descriptions of saxophone sounds was investigated. Sound stimuli were binaurally recorded. Judgements upon perceived qualities were made by saxophonists and non-saxophonists using the method of verbal attribute magnitude estimation. Perceptual dimensions were identified using principal component analysis of listening test data. Three prominent dimensions were found and described using the verbal attributes: 1) warm/soft, 2) back vowel analogues and 3) sharp/rough. The perceptual dimensions were modelled as linear functions of acoustic metrics. The results were validated through listening tests with new subjects and new stimuli. Based on the findings, the method was seen as an approach which can enhance the musical instrument design process.
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| 9. |
- Nykänen, Arne, et al.
(författare)
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Perceptual and acoustical dimensions of saxophone sound
- 2005
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Ingår i: Forum Acusticum Budapest 2005, 4th European Congress on Acoustics. ; , s. 519-524
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Konferensbidrag (refereegranskat)abstract
- Specifications of product sound qualities may contain both perceptual and acoustical descriptions. The perceptual descriptions are most helpful when they contain adequate detail and utilises understandable wording. To facilitate the product design process the descriptions should also be interpretable as acoustical quantities. The objectives of the study reported upon here were to investigate how musicians use verbal descriptions of sound and to interpret these descriptions in terms of commonly used acoustical quantities. Musicians' use of verbal descriptions of saxophone sound was investigated through interviews. The most frequently used words were evaluated through listening tests. The subjects were asked to judge how well the words described the timbre of test sounds. To find the most significant perceptual dimensions for the test sounds Principal Component Analysis was used. Four significant dimensions were found and described by 9 words. To interpret the perceptual dimensions in terms of physically measurable indices, models for how acoustical quantities relate to the perceptual dimensions were developed. Dimension 1 was described by full-toned/warm/soft. The psycho-acoustical quantity sharpness correlated negatively with this dimension. Dimension 2 was described by the term [o]-like. Sharpness and specific roughness (9-11 Bark) correlated negatively with this dimension. Dimension 3 was described by sharp/keen/rough. Sharpness and roughness correlated with this dimension. Dimension 4 was described by the term [e]-like. No model for prediction of this dimension was found. To validate the models the effect of a changed design of the tone holes of a saxophone was predicted with the model and validated with new listening tests.
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| 10. |
- Skogberg, Gabriel, et al.
(författare)
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Altered expression of autoimmune regulator in infant down syndrome thymus, a possible contributor to an autoimmune phenotype.
- 2014
-
Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 193:5, s. 2187-95
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Tidskriftsartikel (refereegranskat)abstract
- Down syndrome (DS), caused by trisomy of chromosome 21, is associated with immunological dysfunctions such as increased frequency of infections and autoimmune diseases. Patients with DS share clinical features, such as autoimmune manifestations and specific autoantibodies, with patients affected by autoimmune polyendocrine syndrome type 1. Autoimmune polyendocrine syndrome type 1 is caused by mutations in the autoimmune regulator (AIRE) gene, located on chromosome 21, which regulates the expression of tissue-restricted Ags (TRAs) in thymic epithelial cells. We investigated the expression of AIRE and TRAs in DS and control thymic tissue using quantitative PCR. AIRE mRNA levels were elevated in thymic tissue from DS patients, and trends toward increased expression of the AIRE-controlled genes INSULIN and CHRNA1 were found. Immunohistochemical stainings showed altered cell composition and architecture of the thymic medulla in DS individuals with increased frequencies of AIRE-positive medullary epithelial cells and CD11c-positive dendritic cells as well as enlarged Hassall's corpuscles. In addition, we evaluated the proteomic profile of thymic exosomes in DS individuals and controls. DS exosomes carried a broader protein pool and also a larger pool of unique TRAs compared with control exosomes. In conclusion, the increased AIRE gene dose in DS could contribute to an autoimmune phenotype through multiple AIRE-mediated effects on homeostasis and function of thymic epithelial cells that affect thymic selection processes.
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| 11. |
- Sudireddy, B. R., et al.
(författare)
-
Development of Robust Metal-Supported SOFCs and Stack Components in EU METSAPP Consortium
- 2017
-
Ingår i: Fuel Cells. - : Wiley. - 1615-6846 .- 1615-6854. ; 17:4, s. 508-516
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Tidskriftsartikel (refereegranskat)abstract
- The potential of MS-SOFCs was demonstrated through the previous EU METSOFC project, which concluded that the development of oxidation resistant novel metal-supported solid oxide fule cell (MS-SOFC) design and stack is the requirement to advance this technology to the next level. The following EU METSAPP project has been executed with an overall aim of developing advanced metal-supported cells and stacks based on a robust, reliable and up-scalable technology. During the project, oxidation resistant nanostructured anodes based on modified SrTiO3 were developed and integrated into MS-SOFCs to enhance their robustness. In addition, the manufacturing of metal-supported cells with different geometries, scalability of the manufacturing process was demonstrated and more than 200 cells with an area of approximate to 150 cm(2) were produced. The electrochemical performance of different cell generations was evaluated and best performance and stability combination was observed with doped SrTiO3 based anode designs. Furthermore, numerical models to understand the corrosion behavior of the MS-SOFCs were developed and validated. Finally, the cost effective concept of coated metal interconnects was developed, which resulted in 90% reduction in Cr evaporation, three times lower Cr2O3 scale thickness and increased lifetime. The possibility of assembling these cells into two radically different stack designs was demonstrated.
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| 12. |
- Tengvall, Katarina, 1980-, et al.
(författare)
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Molecular mimicry between Anoctamin 2 and Epstein-Barr virus nuclear antigen 1 associates with multiple sclerosis risk
- 2019
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 116:34, s. 16955-16960
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Tidskriftsartikel (refereegranskat)abstract
- Multiple sclerosis (MS) is a chronic inflammatory, likely autoimmune disease of the central nervous system with a combination of genetic and environmental risk factors, among which Epstein-Barr virus (EBV) infection is a strong suspect. We have previously identified increased autoantibody levels toward the chloride-channel protein Anoctamin 2 (ANO2) in MS. Here, IgG antibody reactivity toward ANO2 and EBV nuclear antigen 1 (EBNA1) was measured using bead-based multiplex serology in plasma samples from 8,746 MS cases and 7,228 controls. We detected increased anti-ANO2 antibody levels in MS (P = 3.5 x 10(-36)) with 14.6% of cases and 7.8% of controls being ANO2 seropositive (odds ratio [OR] = 1.6; 95% confidence intervals [95% CI]: 1.5 to 1.8). The MS risk increase in ANO2-seropositive individuals was dramatic when also exposed to 3 known risk factors for MS: HLA-DRB1*15: 01 carriage, absence of HLA-A*02: 01, and high anti-EBNA1 antibody levels (OR = 24.9; 95% CI: 17.9 to 34.8). Reciprocal blocking experiments with ANO2 and EBNA1 peptides demonstrated antibody cross-reactivity, mapping to ANO2 [aa 140 to 149] and EBNA1 [aa 431 to 440]. HLA gene region was associated with anti-ANO2 antibody levels and HLADRB1*04: 01 haplotype was negatively associated with ANO2 seropositivity (OR = 0.6; 95% CI: 0.5 to 0.7). Anti-ANO2 antibody levels were not increased in patients from 3 other inflammatory disease cohorts. The HLA influence and the fact that specific IgG production usually needs T cell help provides indirect evidence for a T cell ANO2 autoreactivity in MS. We propose a hypothesis where immune reactivity toward EBNA1 through molecular mimicry with ANO2 contributes to the etiopathogenesis of MS.
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| 13. |
- Warntjes, Marcel Jan Bertus, et al.
(författare)
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Improved Precision of Automatic Brain Volume Measurements in Patients with Clinically Isolated Syndrome and Multiple Sclerosis Using Edema Correction
- 2018
-
Ingår i: American Journal of Neuroradiology. - : AMER SOC NEURORADIOLOGY. - 0195-6108 .- 1936-959X. ; 39:2, s. 296-302
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: The presence of edema will result in increased brain volume, which may obscure progressing brain atrophy. Similarly, treatment-induced edema reduction may appear as accelerated brain tissue loss (pseudoatrophy). The purpose of this study was to correlate brain tissue properties to brain volume, to investigate the possibilities for edema correction and the resulting improvement of the precision of automated brain volume measurements. MATERIALS AND METHODS: A group of 38 patients with clinically isolated syndrome or newly diagnosed MS were imaged at inclusion and after 1, 2, and 4 years using an MR quantification sequence. Brain volume, relaxation rates (R-1 and R-2), and proton density were measured by automated software. RESULTS: The reduction of normalized brain volume with time after inclusion was 0.273%/year. The mean SDs were 0.508%, 0.526%, 0.454%, and 0.687% at baseline and 1, 2, and 4 years. Linear regression of the relative change of normalized brain volume and the relative change of R-1, R-2, and proton density showed slopes of -0.198 (P amp;lt; .001), 0.156 (P = .04), and 0.488 (P amp;lt; .001), respectively. After we applied the measured proton density as a correction factor, the mean SDs decreased to 24.2%, 4.8%, 33.3%, and 17.4%, respectively. The observed atrophy rate reduced from 0.273%/year to 0.238%/year. CONCLUSIONS: Correlations between volume and R-1, R-2, and proton density were observed in the brain, suggesting that a change of brain tissue properties can affect brain volume. Correction using these parameters decreased the variation of brain volume measurements and may have reduced the effect of pseudoatrophy.
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| 14. |
- Abord-Hugon Nonet, Guénola, et al.
(författare)
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PRME Nordic Chapter
- 2021. - 1
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Ingår i: Responsible management education. - London : Routledge. - 9781032030272 - 9781032030296 - 9781003186311 ; , s. 182-197
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Bokkapitel (refereegranskat)
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| 15. |
- Achterberg, A., et al.
(författare)
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First Year Performance of the IceCube Neutrino Telescope
- 2006
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 26:3, s. 155-173
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Tidskriftsartikel (refereegranskat)abstract
- The first sensors of the IceCube neutrino observatory were deployed at the South Pole during the austral summer of 2004-2005 and have been producing data since February 2005. One string of 60 sensors buried in the ice and a surface array of eight ice Cherenkov tanks took data until December 2005 when deployment of the next set of strings and tanks began. We have analyzed these data, demonstrating that the performance of the system meets or exceeds design requirements. Times are determined across the whole array to a relative precision of better than 3 ns, allowing reconstruction of muon tracks and light bursts in the ice, of air-showers in the surface array and of events seen in coincidence by surface and deep-ice detectors separated by up to 2.5 km.
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| 16. |
- Achterberg, A., et al.
(författare)
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Limits on the Muon Flux from Neutralino Annihilations at the Center of the Earth with AMANDA
- 2006
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 26:2, s. 129-139
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Tidskriftsartikel (refereegranskat)abstract
- A search has been performed for nearly vertically upgoing neutrino-induced muons with the Antarctic Muon And Neutrino Detector Array (AMANDA), using data taken over the three year period 1997-99. No excess above the expected atmospheric neutrino background has been found. Upper limits at 90% confidence level have been set on the annihilation rate of neutralinos at the center of the Earth, as well as on the muon flux at AMANDA induced by neutrinos created by the annihilation products.
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| 17. |
- Achterberg, A., et al.
(författare)
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On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
- 2006
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 26:4-5, s. 282-300
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Tidskriftsartikel (refereegranskat)abstract
- The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper.The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II highenergy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.
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| 18. |
- Ahmadzadeh, Farzaneh, et al.
(författare)
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Application of multi regressive linear model and neural network for wear prediction of grinding mill liners
- 2013
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Ingår i: International Journal of Advanced Computer Sciences and Applications. - 2158-107X .- 2156-5570. ; 4:5, s. 53-58
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Tidskriftsartikel (refereegranskat)abstract
- The liner of an ore grinding mill is a critical component in the grinding process, necessary for both high metal recovery and shell protection. From an economic point of view, it is important to keep mill liners in operation as long as possible, minimising the downtime for maintenance or repair. Therefore, predicting their wear is crucial. This paper tests different methods of predicting wear in the context of remaining height and remaining life of the liners. The key concern is to make decisions on replacement and maintenance without stopping the mill for extra inspection as this leads to financial savings. The paper applies linear multiple regression and artificial neural networks (ANN) techniques to determine the most suitable methodology for predicting wear. The advantages of the ANN model over the traditional approach of multiple regression analysis include its high accuracy.
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| 19. |
- Ahmadzadeh, Farzaneh, et al.
(författare)
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Multivariate process parameter change identification by neural network
- 2013
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 69:9-12, s. 2261-2268
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Tidskriftsartikel (refereegranskat)abstract
- Whenever there is an out-of-control signal in process parameter control charts, maintenance engineers try to diagnose the cause near the time of the signal which is not always lead to prompt identification of the source(s) of the out-of-control condition and this in some cases yields to extremely high monetary loses for manufacture owner. This paper applies multivariate exponentially weighted moving average (MEWMA) control charts and neural networks to make the signal identification more effective. The simulation of this procedure shows that this new control chart can be very effective in detecting the actual change point for all process dimension and all shift magnitudes considered. This methodology can be used in manufacturing and process industries to predict change points and expedite the search for failure causing parameters, resulting in improved quality at reduced overall cost. This research shows development of MEWMA by usage of neural network for identifying the step change point and the variable responsible for the change in the process mean vector.
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| 20. |
- Ahmadzadeh, Farzaneh, et al.
(författare)
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Remaining useful life estimation : Review
- 2014
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Ingår i: International Journal of Systems Assurance Engineering and Management. - : Springer Science and Business Media LLC. - 0975-6809 .- 0976-4348. ; 5:4, s. 461-474
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews the recent modelling developments in estimating the remaining useful life (RUL) of industrial systems. The RUL estimation models are categorized into experimental, data driven, physics based and hybrid approaches. The paper reviews some typical approaches and discusses their advantages and disadvantages. According to the literature, the selection of the best model depends on the level of accuracy and availability of data. In cases of quick estimations which are less accurate, the data driven method is preferred, while the physics based approach is applied when the accuracy of estimation is important.
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| 21. |
- Ahmadzadeh, Farzaneh, et al.
(författare)
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Remaining useful life prediction of grinding mill liners using an artificial neural network
- 2013
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875 .- 1872-9444. ; 53, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Knowing the remaining useful life of grinding mill liners would greatly facilitate maintenance decisions. Now, a mill must be stopped periodically so that the maintenance engineer can enter, measure the liners’ wear, and make the appropriate maintenance decision. As mill stoppage leads to heavy production losses, the main aim of this study is to develop a method which predicts the remaining useful life of the liners, without needing to stop the mill. Because of the proven ability of artificial neural networks (ANNs) to recognize complex relationships between input and output variables, as well as its adaptive and parallel information-processing structure, an ANN has been designed based on the various process parameters which influence wear of the liners. The process parameters were considered as inputs while remaining height and remaining life of the liners were outputs. The results show remarkably high degree of correlation between the input and output variables. The performance of the neural network model is very consistent for data used for training (seen) and testing (unseen).
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| 22. |
- Ahrens, J., et al.
(författare)
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Results from AMANDA
- 2001
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Ingår i: Proceedings, 9th International Workshop, Venice, Italy, March 6-9, 2001. Vol. 1, 2. ; , s. 569-580
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Konferensbidrag (refereegranskat)
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| 23. |
- Al-Chalabi, Hussan, et al.
(författare)
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Case Study: Model for Economic Lifetime of Drilling Machines in the Swedish Mining Industry
- 2015
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Ingår i: The Engineering Economist. - 0013-791X .- 1547-2701. ; 60:2, s. 138-154
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to develop a practical economic replacement decision model to identify the economic lifetime of a mining drilling machine. A data driven optimisation model was developed for operating and maintenance costs, purchase price and machine resale value. Equivalent present value of these costs by using discount rate was considered. The proposed model shows that the absolute optimal replacement time (ORT) of a drilling machine used in one underground mine in Sweden is 115 months. Sensitivity and regression analysis show that the maintenance cost has the largest impact on the ORT of this machine. The proposed decision making model is applicable and useful and can be implemented within the mining industry.
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| 24. |
- Al-Chalabi, Hussan S., et al.
(författare)
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Downtime analysis of drilling machines and suggestions for improvements
- 2014
-
Ingår i: Journal of Quality in Maintenance Engineering. - 1355-2511 .- 1758-7832. ; 20:4, s. 306-332
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose– The purpose of this paper is to analyse and compare the downtime of four drilling machines used in two underground mines in Sweden. The downtime of these machines was compared to show what problems affect downtime and which strategies should be applied to reduce it.Design/methodology/approach– The study collects failure data from a two-year period for four drilling machines and performs reliability analysis. It also performs downtime analysis utilising a log-log diagram with a confidence interval.Findings– There are notable differences in the downtime of most of the studied components for all machines. The hoses and feeder have relatively high downtime. Depending on their downtime, the significant components can be ranked in three groups. The downtime of the studied components is due to reliability problems. The study suggests the need to improve the reliability of critical components to reduce the downtime of drilling machines.Originality/value– The method of analysing the downtime, identifying dominant factors and the interval estimation for the downtime, has never been studied on drilling machines. The research proposed in this paper provides a general method to link downtime analysis with potential component improvement. To increase the statistical accuracy; four case studies was performed in two different mines with completely different working environment and ore properties. Using the above method showed which components need to be improved and suggestions for improvement was proposed and will be implemented accordingly.
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| 25. |
- Al-Chalabi, Hussan, Associate Senior Lecturer, 1972-, et al.
(författare)
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Time Series Forecasting using ARIMA Model : A Case Study of Mining Face Drilling Rig
- 2018
-
Ingår i: ADVCOMP 2018. - : International Academy, Research and Industry Association (IARIA). ; , s. 1-3
-
Konferensbidrag (refereegranskat)abstract
- This study implements an Autoregressive Integrated Moving Average (ARIMA) model to forecast total cost of a face drilling rig used in the Swedish mining industry. The ARIMA model shows different forecasting abilities using different values of ARIMA parameters (p, d, q). However, better estimation for the ARIMA parameters is required for accurate forecasting. Artificial intelligence, such as multi objective genetic algorithm based on the ARIMA model, could provide other possibilities for estimating the parameters. Time series forecasting is widely used for production control, production planning, optimizing industrial processes and economic planning. Therefore, the forecasted total cost data of the face drilling rig can be used for life cycle cost analysis to estimate the optimal replacement time of this rig.
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| 26. |
- Al-Douri, Yamur K., et al.
(författare)
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Risk-based life cycle cost analysis using a two-level multi-objective genetic algorithm
- 2020
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Ingår i: International journal of computer integrated manufacturing (Print). - : Taylor & Francis. - 0951-192X .- 1362-3052. ; 33:10-11, s. 1076-1088
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study has been to develop a two-level multi-objective genetic algorithm (MOGA) to optimize risk-based LCC analysis to find the optimal maintenance replacement time for road tunnel ventilation fans. Level 1 uses a MOGA based on a financial risk model to provide different risk percentages, while level 2 uses a MOGA based on an LCC model to estimate the optimal fan replacement time. Our method is compared with the approach of using a risk-based LCC model. The results are promising, showing that the risk-based LCC offers the possibility of significantly reducing the maintenance costs of the ventilation system by optimising the replacement schedule by considering the risk costs. The risk-based LCC can be used with repairable components, making it applicable, useful and implementable within Swedish Transport Administration (Trafikverket). In this study, MOGA operators have selected the cost of maintenance and risk data through the previous levels using different ways to provide different possible solutions. A drawback of the MOGA based on a risk-based LCC model with regard to its estimation is that a late replacement period over 20-year period might increase the maintenance cost. Therefore, the MOGA does not provide a good solution for a risk-based LCC.
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| 27. |
- Al-Douri, Yamur K., et al.
(författare)
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Time Series Forecasting using a Two-level Multi-objective Genetic Algorithm : A case study of cost data for tunnel fans
- 2018
-
Ingår i: Algorithms. - : MDPI. - 1999-4893. ; 11:8
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to develop a novel two-level multi-objective genetic algorithm (GA) to optimize time series forecasting data for fans used in road tunnels by the Swedish Transport Administration (Trafikverket). The first level is for the process of forecasting time series cost data, while the second level evaluates the forecasting. The first level implements either a multi-objective GA based on the ARIMA model or based on the dynamic regression model. The second level utilises a multi-objective GA based on different forecasting error rates to identify a proper forecasting. Our method is compared with the ARIMA model only. The results show the drawbacks of time series forecasting using the ARIMA model. In addition, the results of the two-level model show the drawbacks of forecasting using a multi-objective GA based on the dynamic regression model. A multi-objective GA based on the ARIMA model produces better forecasting results. In the second level, five forecasting accuracy functions help in selecting the best forecasting. Selecting a proper methodology for forecasting is based on the averages of the forecasted data, the historical data, the actual data and the polynomial trends. The forecasted data can be used for life cycle cost (LCC) analysis.
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| 28. |
- Al-Douri, Yamur K., et al.
(författare)
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Time Series Forecasting using Genetic Algorithm : A Case Study of Maintenance Cost Data For Tunnel Fans
- 2018
-
Ingår i: ADVCOMP 2018. - : International Academy, Research and Industry Association (IARIA). ; , s. 4-9
-
Konferensbidrag (refereegranskat)abstract
- Time series forecasting is widely used as a basis for economic planning, production planning, production control and optimizing industrial processes. The aim of this study has been to develop a novel two-level Genetic Algorithm (GA) to optimize time series forecasting in order to forecast cost data for fans used in road tunnels by the Swedish Transport Administration (Trafikverket). The first level of the GA is responsible for the process of forecasting time series cost data, while the second level evaluates the forecasting. The first level implements GA based on the Autoregressive integrated moving average (ARIMA) model. The second level utilizes a GA based on forecasting error rate to identify a proper forecasting. The results show that GA based on the ARIMA model produces better forecasting results for the labor cost data objects. It was found that a multi-objective GA based on the ARIMA model showed an improved performance. The forecasted data can be used for Life cycle cost (LCC) analysis.
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| 29. |
- Al-Douri, Yamur K.
(författare)
-
Two-Level Multi-Objective Genetic Algorithm for Risk-Based Life Cycle Cost Analysis
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Artificial intelligence (AI) is one of the fields in science and engineering and encompasses a wide variety of subfields, ranging from general areas (learning and perception) to specific topics, such as mathematical theorems. AI and, specifically, multi-objective genetic algorithms (MOGAs) for risk-based life cycle cost (LCC) analysis should be performed to estimate the optimal replacement time of tunnel fan systems, with a view towards reducing the ownership cost and the risk cost and increasing company profitability from an economic point of view. MOGA can create systems that are capable of solving problems that AI and LCC analyses cannot accomplish alone.The purpose of this thesis is to develop a two-level MOGA method for optimizing the replacement time of reparable system. MOGA should be useful for machinery in general and specifically for reparable system. This objective will be achieved by developing a system that includes a smart combination of techniques by integrating MOGA to yield the optimized replacement time. Another measure to achieve this purpose is implementing MOGA in clustering and imputing missing data to obtain cost data, which could help to provide proper data to forecast cost data for optimization and to identify the optimal replacement time.In the first stage, a two-level MOGA is proposed to optimize clustering to reduce and impute missing cost data. Level one uses a MOGA based on fuzzy c-means to cluster cost data objects based on three main indices. The first is cluster centre outliers; the second is the compactness and separation ( ) of the data points and cluster centres; the third is the intensity of data points belonging to the derived clusters. Level two uses MOGA to impute the missing cost data by using a valid data period from that are reduced data in size. In the second stage, a two-level MOGA is proposed to optimize time series forecasting. Level one implements MOGA based on either an autoregressive integrated moving average (ARIMA) model or a dynamic regression (DR) model. Level two utilizes a MOGA based on different forecasting error rates to identify proper forecasting. These models are applied to simulated data for evaluation since there is no control of the influenced parameters in all of the real cost data. In the final stage, a two-level MOGA is employed to optimize risk-based LCC analysis to find the optimal replacement time for reparable system. Level one uses a MOGA based on a risk model to provide a variation of risk percentages, while level two uses a MOGA based on an LCC model to estimate the optimal reparable system replacement time.The results of the first stage show the best cluster centre optimization for data clustering with low and high intensity. Three cluster centres were selected because these centres have a geometry that is suitable for the highest data reduction of 27%. The best optimized interval is used for imputing missing data. The results of the second stage show the drawbacks of time series forecasting using a MOGA based on the DR model. The MOGA based on the ARIMA model yields better forecasting results. The results of the final stage show the drawbacks of the MOGA based on a risk-based LCC model regarding its estimation. However, the risk-based LCC model offers the possibility of optimizing the replacement schedule.However, MOGA is highly promising for allowing optimization compared with other methods that were investigated in the present thesis.
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| 30. |
- Alatalo, Rauno V, et al.
(författare)
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Can Female Preference Explain Sexual Dichromatism In The Pied Flycatcher, Ficedula-Hypoleuca
- 1990
-
Ingår i: Animal Behaviour. - 0003-3472 .- 1095-8282. ; 39, s. 244-252
-
Tidskriftsartikel (refereegranskat)abstract
- How important female choice is for the evolution of male secondary sexual characteristics is controversial. Two field and one laboratory experiment, using the pied flycatcher, were performed to test the female choice aspect of sexual selection. In addition, non-manipulative data from 5 years are presented. The observational data suggest a slight preference for dark males by females but in field experiments in which males had territories at random sites (i.e. they did not choose a territory) or the colour of concurrently arriving males was altered, there was no preference for darker ones. Similarly, oestradiol-treated females did not prefer black or brown males in the laboratory. Thus, there is little support for the idea that female choice has been an important mechanism in the evolution of sexual dichromatism in the pied flycatcher.
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Alkasalias, Twana, et al.
(författare)
-
RhoA knockout fibroblasts lose tumor-inhibitory capacity in vitro and promote tumor growth in vivo
- 2017
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:8, s. E1413-E1421
-
Tidskriftsartikel (refereegranskat)abstract
- Fibroblasts are a main player in the tumor-inhibitory microenvironment. Upon tumor initiation and progression, fibroblasts can lose their tumor-inhibitory capacity and promote tumor growth. The molecular mechanisms that underlie this switch have not been defined completely. Previously, we identified four proteins over-expressed in cancer-associated fibroblasts and linked to Rho GTPase signaling. Here, we show that knocking out the Ras homolog family member A (RhoA) gene in normal fibroblasts decreased their tumor-inhibitory capacity, as judged by neighbor suppression in vitro and accompanied by promotion of tumor growth in vivo. This also induced PC3 cancer cell motility and increased colony size in 2D cultures. RhoA knockout in fibroblasts induced vimentin intermediate filament reorganization, accompanied by reduced contractile force and increased stiffness of cells. There was also loss of wide F-actin stress fibers and large focal adhesions. In addition, we observed a significant loss of a-smooth muscle actin, which indicates a difference between RhoA knockout fibroblasts and classic cancer-associated fibroblasts. In 3D collagen matrix, RhoA knockout reduced fibroblast branching and meshwork formation and resulted in more compactly clustered tumor-cell colonies in coculture with PC3 cells, which might boost tumor stem-like properties. Coculturing RhoA knockout fibroblasts and PC3 cells induced expression of proinflammatory genes in both. Inflammatory mediators may induce tumor cell stemness. Network enrichment analysis of transcriptomic changes, however, revealed that the Rho signaling pathway per se was significantly triggered only after coculturing with tumor cells. Taken together, our findings in vivo and in vitro indicate that Rho signaling governs the inhibitory effects by fibroblasts on tumor-cell growth.
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| 41. |
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| 42. |
- Amanda Collaboration, -, et al.
(författare)
-
Optical Properties of Deep Glacial Ice at the South Pole
- 2006
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202 .- 2169-897X. ; 111:D13, s. D13203-
-
Tidskriftsartikel (refereegranskat)abstract
- We have remotely mapped optical scattering and absorption in glacial ice at the South Pole for wavelengths between 313 and 560 nm and depths between 1100 and 2350 m. We used pulsed and continuous light sources embedded with the AMANDA neutrino telescope, an array of more than six hundred photomultiplier tubes buried deep in the ice. At depths greater than 1300 m, both the scattering coefficient and absorptivity follow vertical variations in concentration of dust impurities, which are seen in ice cores from other Antarctic sites and which track climatological changes. The scattering coefficient varies by a factor of seven, and absorptivity (for wavelengths less than ∼450 nm) varies by a factor of three in the depth range between 1300 and 2300 m, where four dust peaks due to stadials in the late Pleistocene have been identified. In our absorption data, we also identify a broad peak due to the Last Glacial Maximum around 1300 m. In the scattering data, this peak is partially masked by scattering on residual air bubbles, whose contribution dominates the scattering coefficient in shallower ice but vanishes at ∼1350 m where all bubbles have converted to nonscattering air hydrates. The wavelength dependence of scattering by dust is described by a power law with exponent −0.90 ± 0.03, independent of depth. The wavelength dependence of absorptivity in the studied wavelength range is described by the sum of two components: a power law due to absorption by dust, with exponent −1.08 ± 0.01 and a normalization proportional to dust concentration that varies with depth; and a rising exponential due to intrinsic ice absorption which dominates at wavelengths greater than ∼500 nm.
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| 43. |
- Amnå, Erik, et al.
(författare)
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En halv miljard av statens pengar riskerar att slösas bort
- 2007
-
Ingår i: Göteborgs-Posten. ; 2007-09-13, s. 47-47
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Minskade anslag gör att den årliga undersökningen om våra levnadsförhållanden hotas att halveras. Det kan drabba redan svaga grupper som äldre, invandrare och ensamstående föräldrar.
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| 44. |
- Anandika, Rayendra, 1988-, et al.
(författare)
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Limitations of eddy current inspection for the characterization of near-surface cracks in railheads
- 2022
-
Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : Sage Publications. - 0954-4097 .- 2041-3017. ; 236:5, s. 532-544
-
Tidskriftsartikel (refereegranskat)abstract
- Eddy current (EC) testing is the most commonly used method to inspect near-surface cracks in railheads. Monitoring surface defects periodically is important to assess the track quality for serving daily operations. Nevertheless, despite being used in many countries, this method has limitations when characterizing cracks under the rail surface. Theoretically, EC testing is unreliable for the inspection of many cracks situated too close to each other in a concentrated location. This study has aimed to prove these limitations. EC signals from inspected cracks were compared with real crack profile parameters, i.e. depth and area, which were delivered by slicing the inspected cracked spots into 0.65 mm-thick pieces. The results show that the EC signal responses to the parameters of area and depth may lead to misleading measurements of the near-surface crack depth in the railhead. For instance, a shallower crack with a larger area can generate a higher EC signal response than a deeper crack with a smaller area. Another important conclusion is that the EC testing in this experiment could not be used to measure densely located cracks, which are those near-surface cracks which are typically found in a rail track.
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| 45. |
- Anandika, Rayendra, 1988-, et al.
(författare)
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Non-destructive measurement of artificial near-surface cracks for railhead inspection
- 2019
-
Ingår i: Insight. - UK : The British Institute of Non-Destructive Testing. - 1354-2575 .- 1754-4904. ; 61:7, s. 373-379
-
Tidskriftsartikel (refereegranskat)abstract
- This paper delivers a study involving the inspection of artificial surface cracks with depths ranging from 0.25-2.5 mm from the surface and with a crack angle of 30°, which is a typical angle for surface cracks in railheads. The inspections were conducted using three different techniques: phased array ultrasonics, single-element ultrasonics and alternating current potential drop (ACPD). For the ultrasonic techniques, the study focused on employing either longitudinal or shear wave signals. In the railway industry, shallow surface cracks in railheads are caused by rolling contact fatigue (RCF). In this study, artificial defects were made, allowing the authors to explore the extent to which the ultrasonic measurement techniques can detect such defects. The negative effect of a dead zone near to the surface in the ultrasonic tests was reduced by using a wedge attachment. A discussion on the extent to which the techniques can be used in field tests was also provided. The most important result is that shallow cracks ranging from 0.25-2.5 mm were successfully characterised with acceptable accuracy. The 2.5 mm-deep crack can be measured with an accuracy of 0.8% using a 20 MHz single-element probe and with an accuracy of 3.5% using a 5 MHz phased array (64 elements, 0.6 mm pitch). The characterisations were performed using a filtering method that was developed in this study.1675605
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| 46. |
- Anandika, Rayendra, 1988-
(författare)
-
Non-destructive measurement of near-surface cracks in railheads : with focus on ultrasonic inspections
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Near-surface cracks in railhead that caused by rolling contact fatigue (RCF) is one of a kind rail defects that degrade rail track quality. Dependent on the trail load, the cracks can reach to severe level quickly. From many studies, the crack growth can be summarized as follows: At the first phase, the crack is initiated at the rail surface due to shear stresses created by the interaction between wheel and rail. The crack then propagates at about 30⁰ angle underneath. After a certain period of transition, the cracks starts propagating horizontally, vertically, or branching. If they propagates horizontally, the cracks potentially cause rail spalling. If they propagates vertically, then the cracks become more severe and dangerous.To overcome such defects, the infrastructure manager remove the top of railhead by performing rail grinding periodically. Prior the grinding, rail tracks need to be inspected to figure out how deep the cracks are by performing non-destructive testing (NDT). Eddy current testing (ECT) is one of the common method to estimate rail surface crack depths. Most of the practices in the industry, ECT estimates only the crack depth, without analyzing any other crack parameters, such as crack angle propagation, crack length, crack area, crack branches, etc. It also has no ability to identify multi-leveled cracks, sub surface cracks, dense cracks etc. Since depth is the only crack parameter that can be provided from ECT, the inspector have no knowledge about how severe the surface crack is. Whereas, information of crack phase, that is known from the crack profile (crack angle, crack depth and crack length) is beneficial to determine whether the crack is in initial or severe level. It also helps to decide the right time for grinding and avoid severe cracks remain long in the rails.Motivated by the benefit of knowing crack parameters, in this study, phased array ultrasonic transducer (PAUT) was used to inspect rail surface cracks. Generally, ultrasonic testing is used to inspect defect of rails at the far-field of the surface, such as at the body or bottom of the rails. Ultrasonic testing is not used to inspect near-surface cracks since the existence of dead zone at the few mm front of the transducer that is caused by piezoelectric crystal ringing inside the transducer. In this study, by utilizing wedge, phased array technique, and setting the optimum gain at the calibration process could decrease the existence of the dead zone. Thus the surface cracks can be observed clearly from the breaking surface to the deepest tip. At the measurement result, crack profile (propagation angle, depth and length), crack branches and multi-level cracks could be observed well. To verify the measurement result, the inspected railheads were sliced into pieces with uniform 0.65-mm thickness. From these pieces, 3D cracks networks were reconstructed. Complete information of crack profiles (angle, depth and length) of all cracks under the inspected surfaces were collected and well presented. From the reconstructed crack images, crack tips, multi-level cracks, and crack branches can be seen. These confirms that the measurement results could be used to observe crack profile well. For a brief description about the results, 3.5 mm crack tip depth and 6 mm crack length were estimated well with 8% and 4% error, respectively. Although the measurement system still have lack of detection for crack path that oriented sharply from the horizontal line parallel to the surface, since the ultrasonic waves could not be reflected back by these paths.At the end of this study, assessment about the potential of measurement speed of the used system when be applied to the rail field inspection was presented. The study is based on the state of the art available at this topic. The discussion is provided in order to motivate the application of the system to be chosen by the rail inspector to use it for the real rail field inspection.
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| 47. |
- Anandika, Rayendra, 1988-, et al.
(författare)
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Phased array ultrasonic inspection of near-surface cracks in a railhead and its verification with rail slicing
- 2020
-
Ingår i: Insight. - United Kingdom : The British Institute of Non-Destructive Testing. - 1354-2575 .- 1754-4904. ; 62:7, s. 387-395
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, near-surface cracks in a railhead are inspected thoroughly using phased array ultrasonic testing (PAUT). This research finds an alternative technique to inspect for near-surface cracks because the conventional non-destructive testing method for rail inspection lacks the capacity to inspect the near-surface crack profile. This study shows that PAUT can determine not only the crack depth but also the near-surface crack profile, so that the inspector can estimate the stage of crack growth and how the crack propagates. This information is valuable to the rail maintainer as one of the considerations for deciding the thickness of metal to remove when grinding the rail. In this study, after the measurement, the inspected region of the cracked railhead is sliced into thin pieces so that crack network information can be extracted. A 3D image reconstruction of the surface cracks based on the crack marks from all of the sliced rail pieces is performed. This image is then used as a reference to confirm the PAUT results. The results show that PAUT can clearly deliver crack profile estimation and provide an accurate estimation of a 3.51 mm crack-tip depth with an absolute error range of 8%-18%. The results also suggest that PAUT is a potential method for installation in a measurement train for near-surface crack inspection.
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| 48. |
- Anandika, Rayendra, 1988-, et al.
(författare)
-
Ultrasonic phased array measurement of near-surface cracks in the railhead.
- 2019
-
Ingår i: World Congress on Railway Research (WCRR) 2019, Tokyo, Japan. - : Railway Technical Research Institute (RTRI, Japan).
-
Konferensbidrag (refereegranskat)abstract
- Ultrasonic measurement is one of the non-destructive techniques used to inspect defects in the rail body. Ultrasonic measurement is known inappropriate to inspect near-surface defects because of a challenge, called dead-zone. It is signal noise or ringing phenomenon located at near-field in front of the transducer when measuring a material. Due to this, there is difficulty in analysing any measurement signal at this zone, including signals from near-surface defects. In this study, the dead zone was eliminated by attaching wedge to shift the location of noise signals relative to the near-surface defect locations. First, a known-depth defect was measured by using phased array ultrasonic testing (PAUT) to calibrate the ultrasonic equipment and found the best signal gain to eliminate diffuse scattering from defects. Second, a cracked spot on railhead was inspected at the right and left direction of the spot. After the measurement, the inspected spot was sliced into 0.65 mm-thick pieces. From those pieces, the actual crack depth could be observed directly. Based on those sliced pieces, the ultrasonic measurement results were verified. From this study, PAUT delivered accurate measurement result of 3.51-mm crack tip depth with an absolute error of 0.8% - 18%. This accurate result indicates that PAUT can be an alternative to inspect the near-surface crack in railhead.
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| 49. |
- Andersson, Agneta, et al.
(författare)
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Can Humic Water Discharge Counteract Eutrophication in Coastal Waters?
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:4, s. e61293-
-
Tidskriftsartikel (refereegranskat)abstract
- A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. We here show that this concept may be questioned in certain scenarios. Climate change has been predicted to cause increased inflow of freshwater to coastal areas in northern Europe. River waters in these areas are often brown from the presence of high concentrations of allochthonous dissolved organic carbon ( humic carbon), in addition to nitrogen and phosphorus. In this study we investigated whether increased inputs of humic carbon can change the structure and production of the pelagic food web in the recipient seawater. In a mesocosm experiment unfiltered seawater from the northern Baltic Sea was fertilized with inorganic nutrients and humic carbon (CNP), and only with inorganic nutrients (NP). The system responded differently to the humic carbon addition. In NP treatments bacterial, phytoplankton and zooplankton production increased and the systems turned net autotrophic, whereas the CNP-treatment only bacterial and zooplankton production increased driving the system to net heterotrophy. The size-structure of the food web showed large variations in the different treatments. In the enriched NP treatments the phytoplankton community was dominated by filamentous >20 mu m algae, while in the CNP treatments the phytoplankton was dominated by picocyanobacteria <5 mu m. Our results suggest that climate change scenarios, resulting in increased humic-rich river inflow, may counteract eutrophication in coastal waters, leading to a promotion of the microbial food web and other heterotrophic organisms, driving the recipient coastal waters to net-heterotrophy.
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| 50. |
- Andersson, Kent, 1967-, et al.
(författare)
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Emerging technology calls for a systemic view on military capability
- 2023
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Ingår i: 1st International Workshop on the Foundations and Applications of Capabilities in Enterprises, Transformations, and ESG Initiatives (FACETE 2023), Aachen, 2023. - Aachen.
-
Konferensbidrag (refereegranskat)abstract
- Many nations are developing their military towards so-called Multi-Domain Operations with artificialintelligence (AI) as a pivotal component, despite identified challenges. Modern-day military operationsunderscore the need for updated battle management and cross-domain communication, central to theprinciples of Joint All-Domain Command and Control (JADC2). AI's potential is obvious, and whileautonomous platforms revolutionize warfare, they introduce complexities in command and control (C2),which is also reflected in capability development. This study identifies suitable concepts for systemicanalysis of military capability and is the starting point in forming a framework for C2 capability developmentin the context depicted. A number of concepts are identified; Combat Power, Fighting Power, Joint functions,Warfighting functions, Elements of combat power, Warfighting Capability, DOTMLPF(I), TEPIDOIL,Fundamental inputs to capability, Defence lines of Development, and Military Power. The study alsohighlights their systemic character and guides the reader briefly in matching issues with suitable concepts.
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