| 1. |
- Berggren, Karolina, et al.
(författare)
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Hydraulic impacts on urban drainage systems due to changes in rainfall, caused by climatic change
- 2012
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Ingår i: Journal of Hydrologic Engineering. - American Society of Civil Engineers. - 1084-0699. ; 17:1
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Tidskriftsartikel (övrigt vetenskapligt)abstract
- The changes in climate were of a growing concern in the last decade, and will be even more so in the coming years. When investigating impacts on urban drainage systems due to changes in the climate, two challenges are (1) what type of input rainfall data to use, and (2) what parameters to measure the impacts. The overall objective of this study is to investigate the hydraulic performances of urban drainage systems related to changes in rainfall, and through these hydraulic parameters describe impacts of climate change. Input rainfall data represents today's climate, as well as three future time periods (2011-2040, 2041-2070, and 2071-2100). The hydraulic parameters used were water levels in nodes (e.g. as the number of floods, frequency and duration of floods), and pipe flow ratio. For the study area, the number of flooded nodes and the geographical distribution of floods will increase in the future, as will both the flooding frequency and the duration of floods.
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| 2. |
- Gustafsson, Gustaf, et al.
(författare)
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Smoothed particle hydrodynamic simulation of iron ore pellets flow
- 2007
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Ingår i: Materials Processing and Design: Modeling, Simulation and Applications : NUMIFORM 2007, Proceedings of the 9th International Conference on Numerical Methods in Industrial Forming Processes. - Melville, NY : American Institute of Physics. - 978-0-7354-0415-1 - 978-0-7354-0416-1 ; 1483-1488
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Annan publikation (populärvet., debatt m.m.)abstract
- In this work the Smoothed Particle Hydrodynamics (SPH) method is used to simulate iron ore pellets flow. A continuum material model describing the yield strength, elastic and plastic parameters for pellets as a granular material is used in the simulations. The most time consuming part in the SPH method is the contact search of neighboring nodes at each time step. In this study, a position code algorithm for the contact search is presented. The cost of contact searching for this algorithm is of the order of Nlog2N, where N is the number of nodes in the system. The SPH-model is used for simulation of iron ore pellets silo flow. A two dimensional axisymmetric model of the silo is used in the simulations. The simulation results are compared with data from an experimental cylindrical silo, where pellets are discharged from a concentric outlet. Primary the flow pattern is compared.
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| 3. |
- Nordebo, Sven, et al.
(författare)
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Electromagnetic dispersion modeling and measurements for HVDC power cables
- 2011
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Rapport (övrigt vetenskapligt)abstract
- This paper provides a general framework for electromagnetic modeling, computation and measurements regarding the wave propagation characteristics of High-Voltage Direct Current (HVDC) power cables. The modeling is focused on very long (10 km or more) HVDC power cables and the relevant frequency range is therefore 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 and the related characteristic impedance. Experimental time-domain measurement data from an 80 km long HVDC power cable is used to validate the model. It is concluded that a single-mode transmission line model is not adequate to account for the mismatch between the power cable and the instrumentation. A mismatch calibration procedure is therefore devised to account for the connection between the measurement equipment and the cable. A dispersion model is thus obtained that is accurate for early times of pulse arrival. To highlight the potential of accurate electromagnetic modeling, an example of high-resolution length-estimation is discussed and analyzed using statistical methods based on the Cramer-Rao lower bound. The analysis reveals that the estimation accuracy based on the present model (and its related model error) is in the order of 100 m for an 80 km long power cable, and that the potential accuracy using a perfect model based on the given measurement data is in the order of centimeters.
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| 4. |
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| 5. |
- Nordebo, Sven, et al.
(författare)
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Wave modeling and fault localization for underwater power cables
- 2011
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Ingår i: 2011 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC). - 978-1-4577-0046-0 ; s. 698-701
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Konferensbidrag (refereegranskat)abstract
- This paper describes some preliminary results regarding Time-Domain pulse Reflection (TDR) measurements and modeling performed on the Baltic Cable submarine HVDC link between southern Sweden and northern Germany. The measurements were conducted in collaboration between the Linnaeus University, Lund University, Baltic Cable AB and ABB High Voltage Cables AB, and is part of the research project: “Fundamental wave modeling for signal estimation on lossy transmission lines”. Preliminary results on measurements and modeling are included here, as well as a first numerical study regarding the low-frequency dispersion characteristics of power cables. The numerical study shows that the finite conductivity of the cable lead shield has a great impact on the losses at low frequencies (0-1 kHz), and that the low-frequency asymptotics of the propagation constant is consistent with common propagation models based on the skin-effect.
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| 6. |
- Aeppli, Christoph, et al.
(författare)
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Use of Cl and C Isotopic Fractionation to Identify Degradation and Sources of Polychlorinated Phenols : Mechanistic Study and Field Application
- 2013
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Ingår i: Environmental Science and Technology. - 0013-936X. ; 47:2, s. 790-797
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Tidskriftsartikel (refereegranskat)abstract
- The widespread use of chlorinated phenols (CPs) as a wood preservative has led to numerous contaminated sawmill sites. However, it remains challenging to assess the extent of in situ degradation of CPs. We evaluated the use of compound-specific chlorine and carbon isotope analysis (Cl- and C-CSLA) to assess CP biotransformation. In a laboratory system, we measured isotopic fractionation during oxidative 2,4,6-trichlorophenol dechlorination by representative soil enzymes (C. fumago chloroperoxidase, horseradish peroxidase, and laccase from T. versicolor). Using a mathematical model, the validity of the Rayleigh approach to evaluate apparent kinetic isotope effects (AKIE) was confirmed. A small but significant Cl-AKIE of 1.0022 +/- 0.0006 was observed for all three enzymes, consistent with a reaction pathway via a cationic radical species. For carbon, a slight inverse isotope effect was observed (C-AKIE = 0.9945 +/- 0.0019). This fractionation behavior is clearly distinguishable from reported reductive dechlorination mechanisms. Based on these results we then assessed degradation and apportioned different types of technical CP mixtures used at two former sawmill sites. To our knowledge, this is the first study that makes use of two-element CSIA to study sources and transformation of CPs in the environment.
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| 7. |
- Andersson, Mats R., et al.
(författare)
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Electroluminescence from Substituted Poly(thiophenes) : From Blue to Near-Infrared
- 1995
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Ingår i: Macromolecules. - American Chemical Society. - 0024-9297. ; 28:22, s. 7525-7529
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Tidskriftsartikel (refereegranskat)abstract
- We report a systematic approach to the control of the conjugation length along the poly(thiophene) backbone. The planarity of the main chain can be permanently modified by altering the pattern of substitution and character of the substituents on the poly(thiophene) chain, and the conjugation length is thus modified. We obtain blue, green, orange, red, and near-infrared electroluminescence from four chemically distinct poly(thiophenes). The external quantum efficiencies are in the range of 0.01-0.6%.
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