| 1. |
- Jonsson, Ulf G, et al.
(författare)
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Modeling the high-frequency complex modulus of a silicone rubber using standing lamb waves and an inverse finite element method
- 2014
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Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - : IEEE Press. - 0885-3010 .- 1525-8955. ; 61:12, s. 2106-2120
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Tidskriftsartikel (refereegranskat)abstract
- To gain an understanding of the high-frequency elastic properties of silicone rubber, a finite element model of a cylindrical piezoelectric element, in contact with a silicone rubber disk, was constructed. The frequency dependent elastic modulus of the silicone rubber was modeled by a four parameter fractional derivative viscoelastic model in the 100 kHz to 250 kHz frequency range. The calculations were carried out in the range of the first radial resonance frequency of the sensor. At the resonance, the hyperelastic effect of the silicone rubber was modeled by a hyperelastic compensating function. The calculated response was matched to the measured response by using the transitional peaks in the impedance spectrum that originates from the switching of standing Lamb wave modes in the silicone rubber. To validate the results, the impedance responses of three 5 mm thick silicone rubber disks, with different radial lengths, were measured. The calculated and measured transitional frequencies have been compared in detail. The comparison showed very good agreement, with average relative differences of 0.7 %, 0.6 %, and 0.7 % for the silicone rubber samples with radial lengths of 38.0 mm, 21.4 mm, and 11.0 mm, respectively. The average, complex, elastic modulus of the samples were: (0.97 + 0.009i) GPa at 100 kHz and (0.97 + 0.005i) GPa at 250 kHz.
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| 2. |
- Morgan, G., et al.
(författare)
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Mental state language and quality of conversational experience in deaf and hearing children
- 2014
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Ingår i: Cognitive development. - : Elsevier BV. - 0885-2014. ; 29:1, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- Deaf children of hearing parents show a protracted delay in performance on 'theory of mind' measures that suggests they encounter difficulties in acquiring knowledge of false beliefs and other mental states. Considerable evidence indicates that children's early experience of adults' mental state talk predicts their later social-cognitive development. However, no previous study has analyzed very young deaf children's access to conversation about mental states. We compared the conversational turn-taking and input of hearing parents to deaf and hearing children aged 17-35 months in the UK and Sweden. Mothers of hearing children used far more cognitive mental state language with their infants and their conversations were characterized by more communicatively effective turn-taking than mothers of deaf children. Across two different cultures, these findings indicate that conversations differ significantly in these aspects of interaction thought to be crucial for later social-cognitive development. © 2013 Elsevier Inc.
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| 3. |
- Röijezon, Ulrik, et al.
(författare)
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Nordic Dedication to Musicians' Health and Performance : A Successful Launch of the First Nordic Conference
- 2014
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Ingår i: Medical problems of performing artists. - : Science and Medicine, Inc.. - 0885-1158 .- 1938-2766. ; 29:4, s. 243-245
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Tidskriftsartikel (refereegranskat)abstract
- Within the last 30 years performing arts medicine has grown internationally as a scientific and clinical specialty for investigation, examination, treatment, and prevention of disorders among performing arts professionals and amateurs, i.e., dancers, singers, musicians, actors, and others engaged in performing arts. In the Nordic countries, clinical specialization and research regarding the health situation of musicians and other performing artists has been relatively sparse. However, this has gained speed in the last decade and is today a growing field. Musicians' Health and Performance 1st Nordic Conference 2013 took place June 13-14, 2013, at the Acusticum Concert Hall in Piteå in the northern part of Sweden, close to the Arctic circle
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| 4. |
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| 5. |
- Evertsson, Maria, et al.
(författare)
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Multimodal Detection of Iron Oxide Nanoparticles in Rat Lymph Nodes Using Magnetomotive Ultrasound Imaging and Magnetic Resonance Imaging
- 2014
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Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010. ; 61:8, s. 1276-1283
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Tidskriftsartikel (refereegranskat)abstract
- Detection and removal of sentinel lymph nodes (SLN) is important in the diagnosis and treatment of cancer. The SLN is the first regional lymph node draining the primary tumor, and if the cancer has spread, it is most likely to find metastases in the SLN. In this study, we have for the first time been able to image the very same contrast agent, superparamagnetic iron oxide nanoparticles (SPIO-NPs), in rat SLNs by using both our frequency-and phase-gated magnetomotive ultrasound (MMUS) algorithm and conventional magnetic resonance imaging (MRI); MMUS post mortem, MRI in vivo. For both higher NP-concentration and smaller NPs, we found that the MMUS data showed a larger magnetomotive displacement (1.56 +/- 0.43 and 1.94 +/- 0.54 times larger, respectively) and that the MR-images were affected to a higher degree. The MMUS displacement also increased with lower excitation frequency (1.95 +/- 0.64 times larger for 5 Hz compared with 15 Hz) and higher excitation voltage (2.95 +/- 1.44 times larger for 30 V compared with 10 V). The results show that MMUS has potential to be used as bedside guidance during SLN surgery, imaging the same particles that were used in prior staging with other imaging techniques.
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| 6. |
- Gustafsson, Stefan, et al.
(författare)
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Electromagnetic dispersion modeling and measurements for HVDC power cables
- 2014
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Ingår i: IEEE Transactions on Power Delivery. - : IEEE Press. - 0885-8977 .- 1937-4208. ; 29:6, s. 2439-2447
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides a general framework for electromagnetic (EM) modeling, sensitivity analysis, computation, and measurements regarding the wave propagation characteristics of high-voltage direct-current (HVDC) power cables. The modeling is motivated by the potential use with transient analysis, partial-discharge measurements, fault localization and monitoring, and is focused on very long (10 km or more) HVDC power cables with transients propagating in the low-frequency regime of about 0-100 kHz. An exact dispersion relation is formulated together with a discussion on practical aspects regarding the computation of the propagation constant. Experimental time-domain measurement data from an 80-km-long HVDC power cable are used to validate the electromagnetic model, and a mismatch calibration procedure is devised to account for the connection between the measurement equipment and the cable. Quantitative sensitivity analysis is devised to study the impact of parameter uncertainty on wave propagation characteristics. The sensitivity analysis can be used to study how material choices affect the propagation characteristics, and to indicate which material parameters need to be identified accurately in order to achieve accurate fault localization. The analysis shows that the sensitivity of the propagation constant due to a change in the conductivity in the three metallic layers (the inner conductor, the intermediate lead shield, and the outer steel armor) is comparable to the sensitivity with respect to the permittivity of the insulating layer. Hence, proper modeling of the EM fields inside the metallic layers is crucial in the low-frequency regime of 0-100 kHz.
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| 7. |
- Jung, Kyungsub, et al.
(författare)
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Arc Stability Control of a High-Power Thyristor Rectifier System in a DC Arc Furnace
- 2014
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Ingår i: IEEE Transactions on Power Electronics. - 0885-8993. ; 29:12, s. 6342-6351
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Tidskriftsartikel (refereegranskat)abstract
- Fundamental features of the arc stability in a dc arc furnace of 720 V/100 kA/72 MW have been investigated. The Cassie-Mayr arc model has been employed and applied for the target dc arc furnace. In order to characterize the parameters of the Cassie-Mayr arc model and the behavior of unstable arc dynamics, the advanced arc simulations of magneto-hydrodynamics (MHD) have been performed. From the results of MHD simulation, the dc arc dynamic resistance is proposed to be an effective arc stability function reflecting the instability of dynamic arc behavior. A control strategy of the 12-pulse thyristor rectifier system to regulate the arc stability function is also proposed in this paper. The simulation and experimental results confirm the usefulness of the proposed dynamic arc resistance as the arc stability function along with the active control strategy. The proposed arc stability function can be regarded as an effective criterion for the overall power conversion system to maintain highly stable arcing operation leading to better productivity and reliability in a dc arc furnace.
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| 8. |
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| 9. |
- Borris, Matthias, et al.
(författare)
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Modelling the effects of changes in rainfall event characteristics on TSS loads in urban runoff
- 2014
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 28:4, s. 1787-1796
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Tidskriftsartikel (refereegranskat)abstract
- The effect of changes in rainfall event characteristics on urban stormwater quality, which was described by total suspended solids (TSS), was studied by means of computer simulations conducted with the Storm Water Management Model for a climate change scenario for northern Sweden. The simulation results showed that TSS event loads depended mainly on rainfall depth and intensity, but not on antecedent conditions. Storms with low-to-intermediate depths and intensities showed the highest sensitivity to changes in rainfall input, both for percentage and absolute changes in TSS wash-off loads, which was explained by the contribution of pervious areas and supply limitations. This has significant implications for stormwater management, because those relatively frequent events generally carry a high percentage of the annual pollutant load
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| 10. |
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