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| 5. |
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| 6. |
- Kingston, W., et al.
(författare)
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The rock OWC
- 1998
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Ingår i: Third European Wave Energy Conference, Patras, Greece, 30 Sept., - 2 Oct., 1998.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 7. |
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| 8. |
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| 9. |
- Adamsson, Åsa, 1970, et al.
(författare)
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Measurement and three-dimensional simulation of flow in a rectangular detention tank
- 2005
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Ingår i: Urban Water Journal. - 1744-9006 .- 1573-062X. ; 2:4, s. 277-287
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Tidskriftsartikel (refereegranskat)abstract
- There are two main ways to obtain better knowledge of the hydraulics of ponds, namelymeasurements and simulations. In this study, the applicability of using three-dimensionalsimulations as an engineering tool in stormwater pond design was investigated. To dothis, three-dimensional simulations were compared with measurements of flow patternand residence time in a large physical model of a detention tank (13 x 9x 1 m). Theagreement between measurements and simulations concerning both flow pattern andresidence time distribution curves was found to be good for high flow rates.
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| 10. |
- Adamsson, Åsa, 1970, et al.
(författare)
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Simulation of temperature influence on flow pattern and residence time in a detention tank
- 2006
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Ingår i: Nordic Hydrology. - 0029-1277. ; 37:1, s. 53-68
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional simulations were used to model how a temperature difference between the incoming water and tank water influences the flow pattern and residence time in a detention tank. Buoyant, neutrally buoyant and negatively buoyant incoming jets were simulated. The simulations were compared with measurements for neutrally buoyant jets in a large-scale model of a detention tank (13 × 9×1 m). The results show that a negatively buoyant jet gives slightly less effective volume, defined as the time when 50% of added tracer has passed the outlet divided by the nominal residence time, than a neutrally buoyant jet. The flow pattern for a negatively buoyant jet at low densimetric Froude numbers consists of a current that travels along the bottom towards the outlet and a counter current at the surface towards the inlet, while the neutrally buoyant jet excites a surface jet with two large eddies on each side of the jet. This implies that the short-circuiting will decrease when a negatively buoyant jet at low densimetric Froude number occurs in the tank. The difference between the flow pattern excited by a buoyant jet and a neutrally buoyant jet is small.
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| 11. |
- Allenström, Björn, et al.
(författare)
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Amplification of ship generated wake wash due to coastal effects
- 2003
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Ingår i: Transactions - Society of Naval Architects and Marine Engineers. - 0081-1661. ; 111, s. 61-77
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper discusses the results from extensive wake wash measurements carried out with a model of a ROPAX ship passing a bay. The tests were carried out in SSPA 's sea-keeping and maneuvering basin. This model had been subjected to wash wave measurements in open water in previous tests, which gave possibilities for comparisons between restricted and unrestricted waters'. Six wave gauges were placed inside and outside the bay, and a significant drawdown was noticed in addition to amplifications of the Kelvin waves. The drawdown and the Kelvin waves that occurred in the bay are difficult to explain, but this paper makes an attempt to analyze the phenomena that occur. The different wave theories that can be used in this case are presented The methods that are used for analyzing the measured signals are described One conclusion that can be made is that drawdown caused by the Bernoulli wave can probably be considered a worse problem than ordinary wash waves (Kelvin waves) in restricted and especially shallow waters when looking at large displacement ships.
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| 12. |
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| 13. |
- Bergdahl, Lars, 1943
(författare)
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A theory on the elasticity of sea ice
- 1983
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Ingår i: 7'th International Symposium on Port and Ocean Engineering under Arctic Conditions, Espoo 1983. ; , s. 52-68
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The brine content of sea ice influences many of its properties like e.g. thermal conductivity, melting poin and crystal structure. The phase relations of the ice-brine system is described and used for the calculation of the bulk density and elasticity of sea ice. The mechanical strength of sea ice n in relation to brine content is also briefly reviewed.
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| 14. |
- Bergdahl, Lars, 1943
(författare)
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Anchoring problems of large semisubmersibles
- 1982
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The demand for exploration-drilling and production platforms in the hostile environment north of the 62 parallel in the Norwegian Sea has led to the development of ever larger floating platforms, designed not only for drilling and early production but also intended for the final production stage. Also for other purposes like chemical processing it is of nterest with very large platforms
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| 15. |
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| 16. |
- Bergdahl, Lars, 1943
(författare)
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Bestämning av farleders planmått
- 1999
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Ingår i: Svensk Hamntidning. - 0346-2110. ; :1999 Nr 3, s. 1-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 17. |
- Bergdahl, Lars, 1943, et al.
(författare)
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Bevattningsteknik
- 1970
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 18. |
- Bergdahl, Lars, 1943
(författare)
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Chapter 3: Loading Generating Mechanisms, Thermal Ice Pressure
- 1986
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Ingår i: River and lake ice engineering, Water Resources Publications, Chelsea, Michigan, Editor G. Ashton. - 0918334594 ; , s. 102-124
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- When a landfast ice cover has benn formed on a lake or an enclsed part of the sea, stresses arise from the thermal expansion or contraction caused by the changing weather, The stresses eventually exer forces against shores, dams or other structures. It is complicatded to calculate such forces for design purposes because of the nonlinrearity of the deformation of the ice, the irregularity of ice covers, the variation of ice properties, and the difficulty of defining the probability of extreme situations.
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| 19. |
- Bergdahl, Lars, 1943
(författare)
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Chapter 3: Rheology of ice
- 1986
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Ingår i: River and lake ice engineering, Water Resources Publications, Chelsea, Michigan, Editor G. Ashton. - 0918334594 ; , s. 102-124
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Natural ice shows many peculiar properties, distinguishing it from other materials, and it is most important to bear this in mind when studying its mechanics.
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| 20. |
- Bergdahl, Lars, 1943
(författare)
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Deponering av mudder
- 1999
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Ingår i: Svensk Hamntidning. - 0346-2110. ; :1999 Nr 1, s. 1-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 21. |
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| 22. |
- Bergdahl, Lars, 1943, et al.
(författare)
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Dynamically Scaled Model Experiment of a Mooring Cable
- 2016
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Ingår i: Journal of Marine Science Engineering. - : MDPI AG. - 2077-1312. ; 4:1, s. 5-
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic response of mooring cables for marine structures is scale-dependent, and perfect dynamic similitude between full-scale prototypes and small-scale physical model tests is difficult to achieve. The best possible scaling is here sought by means of a specific set of dimensionless parameters, and the model accuracy is also evaluated by two alternative sets of dimensionless parameters. A special feature of the presented experiment is that a chain was scaled to have correct propagation celerity for longitudinal elastic waves, thus providing perfect geometrical and dynamic scaling in vacuum, which is unique. The scaling error due to incorrect Reynolds number seemed to be of minor importance. The 33 m experimental chain could then be considered a scaled 76 mm stud chain with the length 1240 m, i.e., at the length scale of 1:37.6. Due to the correct elastic scale, the physical model was able to reproduce the effect of snatch loads giving rise to tensional shock waves propagating along the cable. The results from the experiment were used to validate the newly developed cable-dynamics code, MooDy, which utilises a discontinuous Galerkin FEM formulation. The validation of MooDy proved to be successful for the presented experiments. The experimental data is made available here for validation of other numerical codes by publishing digitised time series of two of the experiments.
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| 23. |
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| 24. |
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| 25. |
- Bergdahl, Lars, 1943
(författare)
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Forces on a wave-energy module
- 1991
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Ingår i: The third symposium on ocean wave--energy utilisation January 22-23 1991,Tokyo. ; , s. 47-56
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Mathematical models for the calculation of wave forces added mass and radiation damping of a wave energy module is developed in order to assess the energy take-out. The module consists of a buoy connected to a submerged plate by a so-called hose pump.In the present models the buoy and the submerged plate are idealized to two cylinders of equal radii. The presented method is founded on the method of matched eigenfunction expansion. Comparisons with other solutions are presented and the agreement is shown to be satisfactory. The developed models are computer efficient and will be used in an optimization procedure for a wave climate.
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| 26. |
- Bergdahl, Lars, 1943, et al.
(författare)
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Förankringen till en vågenergiboj i Kattegatt
- 1981
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Ingår i: Efaringer fra dagens forankringssystemer og krav til morgendagens. Noges sivilingenjörers forening. ; , s. 18-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Sommaren 1979 genomfördes i sjön Lygnern
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
- Bergdahl, Lars, 1943
(författare)
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Limitation of loading and unloading operations in harbours due to ship motion
- 2005
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Ingår i: Modelling of Water Waves in Harbours, Gdansk, September 5-6, 2005. - 8385708677
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Motions of moored ships in harbours are excited by winds, currents, waves, seiches, tides, passing ships, and cargo handling. This lecture will describe the properties of these excitations as well as the mechanics of the motion response of the ships. Firstly, however, the recommended allowed limits of motions for safe working conditions of various ship types, from pleasure boats to fishing vessels and large bulk carriers, will be described. Such recommendations were presented by PIANC (1995) and the Nordic Council (1986). Following this, a theoretical study of the motion of a ferry at berth in the Port of Visby will be presented, which contains some novel ideas. Lastly, results and animations from some ongoing developments at Chalmers University of Technology on wave computations over large areas with complex topography will be presented.
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| 32. |
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| 33. |
- Bergdahl, Lars, 1943, et al.
(författare)
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Luftbubbelridå som spärr mot gravitationell och vindgenererad spridning av olja på stagnant vatten
- 1968
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Institutionen för vattenbyggnad, Chalmers tekniska högskola, har på uppdrag av AB Atlas Copco utfört en laboratoriemätning av en luftbubbelridås effekivivitet som spärr mot gravitationell och vingenererad spridning av olja på stagnant vatten. Målsättmniongen har varit att försöka bestämma det för erhållande av minimalt oljeläckage erforderliga luftflödet i ridån som funktion av oljans täthet och viskositet vid varierande vind- och vågförhållanden.
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| 34. |
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| 35. |
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| 36. |
- Bergdahl, Lars, 1943
(författare)
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Mooring Design for WECs
- 2016
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Ingår i: Handbook of Ocean Wave Energy. - 9783319398884 ; , s. 159-202
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This Handbook for Ocean Wave Energy aims at providing a guide into the field of ocean wave energy utilization. The handbook offers a concise yet comprehensive overview of the main aspects and disciplines involved in the development of wave energy converters (WECs). The idea for the book has been shaped by the development, research, and teaching that we have carried out at the Wave Energy Research Group at Aalborg University over the past decades. It is our belief and experience that it would be useful writing and compiling such a handbook in order to enhance the understanding of the sector for a wide variety of potential readers, from investors and developers to students and academics.
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| 37. |
- Bergdahl, Lars, 1943
(författare)
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Ny kanal
- 1999
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Ingår i: Svensk Hamntidning. - 0346-2110.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 38. |
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| 39. |
- Bergdahl, Lars, 1943
(författare)
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PIC 1999, Gent, Belgien
- 1999
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Ingår i: Svensk Hamntidning. - 0346-2110.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 40. |
- Bergdahl, Lars, 1943
(författare)
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Probabilities of thermal ice pressures in five Swedish lakes
- 1978
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Ingår i: IAHR Sympsium on ice problems, Luleå, Aug. 7-9 1978.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- For five Swedish lakes the recurrence intervals and magnitudes of ice pressure caused by thermal expansion has been estimated. A numerical model has been developed that calculates the the thermal pressure in an ice cover for observed ice and snow cover characteristicsand observed weather. Maxima of the calculated pressure that exceed 50 kN/m are listed for each lake, and annual-maximum series and peaks-over-threashold series are formed for the lakes. Three types of distributions are fitted to the annual-maximum series and one type to the peaks-over-threshold series. Reasonable esitmates of thexpected pressures of teh rturn periods, 100, 500 and 1000 years are for the northernmost lake Torne Träsk (68,3 deg N, 19,5 deg E) 507, 550 and 569 kN/m and for the southermost lake Vidöstern (57,1 deg N, 14,0 deg E) 330, 380 and 569 kN/m. The number of years varied between 12 and 16.
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| 41. |
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| 42. |
- Bergdahl, Lars, 1943, et al.
(författare)
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Time simulation of the motion of a tension leg platform
- 1988
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Ingår i: BOSS'88 Proceedings of the international conference on behaviour of offshore structures. - 8251908558 ; 2, s. 875-890
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Konferensbidrag (refereegranskat)abstract
- The time-domain motion of a Tension Leg Platform is studied. The used method is based on a convolution technique in which the hydrodynamic reaction force from the frequency-domain solution is Fourier transformed to the time domain. Such a method allows one to consider arbitrary time varying external forces as for example non-linear reaction forces from tendons as well as transient loads.In the developed model time series of first-order wave forces and second-orde slowly varying wave forces are calculated for irregular plane and short-crested waves. Exciting forces due to wind and current are calculated using drag coefficients from model tests. The equations of motion in the time domain are solved for a tension-leg platform performing rigid body motion and results in time series of the motions as well as of the tension in the tendons.Numerical simulations have been carried out and the results are discussed. A comparison is made between calculations and model tests for a tension-leg platform in irregular long-crested waves.
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| 43. |
- Bergdahl, Lars, 1943, et al.
(författare)
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Tredimensionell analys av strömning i va-anläggningar
- 1999
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Ingår i: Bygg & teknik. - 0281-658X. ; 99:2, s. 57-60
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Utvecklingen av datorernas kapacitet under 80-talet skapade nya möjligheter att bättre använda grundläggande samband för analys inom många teknikområden. Ett av dessa var analysen av strömning i vatten- och avloppssystem där flödena är mycket starkt varierande i tid och rum och därmed svåra att simulera
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| 44. |
- Bergdahl, Lars, 1943
(författare)
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Two lighthouses damaged by ice
- 1972
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Ingår i: Symposium on Ice and Its Action on Hydraulic Structures, IAHR, 1972, Leningrad. ; , s. 234-238
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Two cases of damage to lighthouses in the Balic are reported. The maximum ice pressure is estimated from the mode of failure of the lighthouses. The calculations give a horizontal load of 1.1 to 1.7 MN per metre width of structure.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Bergdahl, Lars, 1943
(författare)
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Vågkraftverk
- 1985
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Ingår i: Handboken Bygg Kapitel V37:3. ; , s. 658-661
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Populärvetenskapli beskrivning av vågeneri och vågkraftverk
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| 49. |
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| 50. |
- Bergdahl, Lars, 1943
(författare)
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Vågor och vågkrafter
- 1984
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Kompendium i Kursen Vågor och vågkrafter. Speciellt borr- och produktionsplattformar för offshoreindustrin
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