| 1. |
|
|
| 2. |
- Elfgren, Lennart, 1942-, et al.
(författare)
-
Infrastructure in NW Russia - Potential development : A Pre-feasibility Study with Special Reference to Winter Transportation, Concrete Structures, and Timber Structures
- 2000
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In co-operation with a Finnish Group of researchers a pre-feasibility study was undertaken regarding potential development of the Infrastructure in NW Russia. Special emphasis was given: Winter Transportation and Reinforcement of Load Bearing Ice Covers; Concrete Construction and Strengthening of Concrete Structures; Timber Construction and Mechanical Wood Industry Development; and Energy Conservation and Industrial Energy Development.Based on the study three Russian-Swedish co-operation projects have started:- Load Bearing Ice Covers (Literature Survey)- Forces caused by Ice Crushing against Off-Shore Structures (EC funded Research Project)- Strengthening of a Bridge. Co-operation Stabilator/Skanska - Arkhangelsk Road
|
|
| 3. |
- Erni, W., et al.
(författare)
-
Technical design report for the PANDA (AntiProton Annihilations at Darmstadt) Straw Tube Tracker
- 2013
-
Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 49:2
-
Tidskriftsartikel (refereegranskat)abstract
- This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM stations. The tasks of the STT are the measurement of the particle momentum from the reconstructed trajectory and the measurement of the specific energy loss for a particle identification. Dedicated simulations with full analysis studies of certain proton-antiproton reactions, identified as being benchmark tests for the whole PANDA scientific program, have been performed to test the STT layout and performance. The results are presented, and the time lines to construct the STT are described.
|
|
| 4. |
- Fransson, Lennart, et al.
(författare)
-
Armerad is : fältförsök i full skala
- 1983
-
Ingår i: Väg- och Vattenbyggaren. - 0042-2177. ; :10, s. 24-25
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
|
| 5. |
- Fransson, Lennart, et al.
(författare)
-
Field investigation of load‑curvature characteristics of reinforced ice
- 1986
-
Ingår i: Polartech '86. - Espoo : Technical Research Centre of Finland. - 9513827143 ; , s. 175-196
-
Konferensbidrag (refereegranskat)abstract
- Load-deformation characteristics are studied for three types of top reinforcement in a floating ice cover: (a) sand, (b) birch branches and (c) sawn timber. The curvature of the ice cover is measured during application of a constant load. A three-parameter creep model is proposed for the ice deformation. Expressions are deduced for the characteristic lenght and the maximum deflection of the ice cover based on the curvature.
|
|
| 6. |
|
|
| 7. |
- Nybacka, Mikael, et al.
(författare)
-
Project: CASTT - Centre for Automotive Systems Technologies and Testing
- 2007
-
Annan publikation (populärvet., debatt m.m.)abstract
- Through the Centre for Automotive Systems Technologies and Testing, Luleå University of Technology aims to first of all support automotive winter testing in Northern Sweden. This means to support the local automotive test entrepreneurs and through them their customers: the car manufacturers and their suppliers. To succeed in this task, the center relies on the university's areas of leading research and most importantly on the cooperation between those areas.
|
|
| 8. |
|
|
| 9. |
- Bergdahl, Lars, 1943, et al.
(författare)
-
Waves for design of wind-power plants in shallow seas
- 2009
-
Ingår i: Proceedings of the 20th International Conference on Port and Ocean Engineering under Arctic Conditions. ; 1, s. 1-11
-
Konferensbidrag (refereegranskat)abstract
- Usually there is little knowledge of long-term wave conditions at prospective sites for windpower plants, while the deep-water or open sea conditions may be more known and geographically less varying. However, most wind-energy plants are intended for water depths less than 20 m. A concept for assessing design waves at a near-shore site is to transform the offshore wave spectra to the target site by a model for spectral wave-energy transfer over the actual bottom topography. The inshore spectra can be used for linear statistics of extreme waves and design wave loads can be produced. In this context it is important to know the realism of used spectral forms.Based on 58 measured wave spectra at 6 m water depth at the near-shore wind farm Bockstigen in the Baltic the most realistic spectrum was found to be the TMA spectrum, which is a JONSWAP spectrum modified for shallow water. Some few examples are given.
|
|
| 10. |
- Bergström, Malin, et al.
(författare)
-
Children with two homes: Psychological problems in relation to living arrangements in Nordic 2-to 9-year-olds
- 2019
-
Ingår i: Scand J Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 47:2, s. 137-145
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: Joint physical custody, children spending equal time in each parents' respective home after a parental divorce, is particularly common in Nordic compared with other Western countries. Older children have been shown to fare well in this practice but for young children there are few existing studies. The aim of this paper is to study psychological problems in 2- to 9-year-old Nordic children in different family forms. Methods: Total symptom score according to the Strengths and Difficulties Questionnaire as well as scores showing externalizing problems were compared among 152 children in joint physical custody, 303 in single care and 3207 in nuclear families through multiple linear regression analyses. Results: Children in single care had more psychological symptoms than those in joint physical custody (B = 1.08; 95% CI 0.48 to 1.67) and those in nuclear families had the least reported symptoms (B = -0.53; 95% CI -0.89 to -0.17). Externalizing problems were also lower in nuclear families (B = -0.28, 95% CI -0.52 to -0.04) compared with joint physical custody after adjusting for covariates. Conclusions: Young children with non-cohabiting parents suffered from more psychological problems than those in intact families. Children in joint physical custody had a lower total problem score than those in single care after adjusting for covariates. Longitudinal studies with information on family factors before the separation are needed to inform policy of young children's post-separation living arrangements.
|
|
| 11. |
- Bergström, Malin, et al.
(författare)
-
Mental health in Swedish children living in joint physical custody and their parents' life satisfaction : A cross-sectional study
- 2014
-
Ingår i: Scandinavian Journal of Psychology. - : Wiley. - 0036-5564 .- 1467-9450. ; 55:5, s. 433-439
-
Tidskriftsartikel (refereegranskat)abstract
- This study compared the psychological symptoms of 129 children in joint physical custody with children in single care and nuclear families, using a nationally representative 2011 survey of 1,297 Swedish children aged between four and 18 years. The outcome measure was the Strengths and Difficulties Questionnaire (SDQ) and its association with three dimensions of parental life satisfaction was investigated. Linear regression analyses showed higher SDQ-scores for children in joint physical custody (B=1.4, p<0.001) and single care (B=2.2, p<0.001) than in nuclear families, after adjustment for socio-demographic variables. The estimates decreased to 1.1 and 1.3, respectively, after being adjusted for parental life satisfaction (p<0.01). Our findings confirm previous research that showed lower symptom scores for children in nuclear families than children in single care and joint physical custody. Parental life satisfaction should be investigated further as a possible explanation of differences in symptom load between children in different living arrangements.
|
|
| 12. |
- Bonath, Victoria, et al.
(författare)
-
Isförhållanden inom Luleå hamnbassäng
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Issituationen i Luleå hamn vintern 2012/13 var normalsvår vilket innebar en ökad istillväxt motsvarade 150 cm ren is i områden som bröts kontinuerligt. Detta ska jämföras med det obrutna istäckets tjocklek som var ca 60 cm. Isen i rännan bestod av klotformade isblock (10 – 120 cm) omgivna av issörja. Under mars månad var isblockens storlek mätt vid vattenytan i genomsnitt 45 cm och andelen vatten eller finfördelad issörja var ca 30%. Analyser av isborrkärnor visar att isblocken hade en hållfasthet som ökade med antalet brytningar och var i paritet med det ostörda istäcket i början av mars. Blocken bestod då till 70% av finkrossad is eller frusen snösörja.Isproduktionen i området med bruten is tycks vara linjärt beroende av antalet negativa graddagar där tillväxttakten uppmättes till 0,235 cm per grad och dygn. En numerisk modell för beräkning av istillväxt föreslås där frysning av issörja vid ytan och under isblock ingår. Modellen stämmer bra överens med uppmätta värden från en ränna nära hamnen som bröts kontinuerligt två gånger i veckan. Mer fältstudier av isbildning och uppbrytning är önskvärd för att öka modellens tillförlitlighet under förhållanden som skiljer sig väsentligt från de som rådde i testrännan. Samtliga mätprotokoll från ismätningarna i rännan finns bifogade i rapporten.Tillgänglig statistik visar att antalet negativa graddagar efter isläggningen i Luleå hamn vid en svår isvinter är ca 1000. Våra mätningar tyder på att det under en sådan vinter bildas 2,4 m ren is om ett vändområde används kontinuerligt. Beräkningar med den numeriska modellen resulterade i en möjlig istjocklek på 3 m under en svår vinter om medeltemperaturen är 50% kallare än under den aktuella mätperioden 2012. I nuläget klarar hamnisbrytaren Viscaria att operera och vända fartyg i bruten is motsvarande 1,4 m. Om tjockare is bildas är det väsentligt att ett nytt vändområde med ostörd is kan tas i bruk. Under en svår isvinter krävs därför att minst tre åtskilda vändområden är tillgängliga i Luleå hamn.
|
|
| 13. |
- Bonath, Victoria, et al.
(författare)
-
Laboratory testing of compressive and tensile strength on level ice and ridged ice from Svalbard region
- 2013
-
Ingår i: Proceedings of the 22nd International Conference on Port and Ocean Engineering under Arctic Conditions.
-
Konferensbidrag (refereegranskat)abstract
- Compression and tensile strength properties are important input data for constitutive modelling. Still strength properties of ridged ice are not yet sufficiently investigated. During winter 2011 and 2012 field trips were performed to the Svalbard region with the aim to investigate structure and strength of pressure ridges. Core samples from different ridges and the surrounding level ice were taken and transported to the laboratory at Luleå University of Technology. Studies on thin sections of the ice samples under cross-polarized light delivered information about internal structure of the ice. Uniaxial compressive and tensile strength tests were performed with horizontal and vertical loading directions. The experimental procedure is explained in detail. Salinity and porosity were measured for each sample. In this paper the mechanical properties obtained from the testing are documented by consideration of crystal type, ice depth and total porosity.
|
|
| 14. |
- Bonath, Victoria, et al.
(författare)
-
Morphology, internal structure and formation of ice ridges in the sea around Svalbard
- 2018
-
Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 155, s. 263-279
-
Tidskriftsartikel (refereegranskat)abstract
- The results from 3 years of comprehensive field investigations on first-year ice ridges in the Arctic are presented in this paper. The scopes of these investigations were to fill existing knowledge gaps on ice ridges, gain understanding on ridge characteristics and study internal properties of ice. The ability of developing reliable simulations and load predictions for ridge-structure interactions is the final principal purpose, but beyond the scope of this paper. The presented data comprise ridge geometry, ice block dimensions from ridge sails, ice structure in the ridge and values on the ridge porosity and the degree of consolidation. The total ridge thickness conformed to other ridges studied in the same regions. The consolidated layer thickness was on average 2–3 times the level ice thickness. Minimum 33% and in average 90% of the ridge keel area was consolidated. The distribution of ice block sizes and block shapes within a ridge appears to be predictable. A new approach for deriving a possible ridging scenario and ridge age is presented. Different steps of the ridge building process were identified, which are in good agreement with earlier simulated ridging events. After formation of very thin lead ice between two floes deformation occurs through rafting and ridging until closure of the lead. Subsequently the adjacent level ice floe fractures proceeding ridge formation until ridging forces exceed driving forces. A time span of 10 days could be assessed for a possible ridge formation date, estimating the ridge age of the studied ridge located east of Edgeøya at 78° N to be 7 to 8 weeks.
|
|
| 15. |
- Bonath, Victoria, et al.
(författare)
-
Properties of ice from first-year ridges in the Barents Sea and Fram Strait
- 2019
-
Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 168
-
Tidskriftsartikel (refereegranskat)abstract
- First-year ice ridges are one of the main load scenarios that off-shore structures and vessels operating in ice-covered waters have to be designed for. For simulating such load scenarios, the knowledge gap on ice mechanical properties from the consolidated part of first-year ridges has to be filled. In total 410 small-scale uniaxial compression tests were conducted at different strain rates and ice temperatures on ice from the consolidated layer of 6 different first-year ridges in the sea around Svalbard. For the first time uniaxial tensile tests were performed on ice from first-year ridges using a new testing method. Ice strength was evaluated for different ice type, which are determined for each specimen based on a proposed ice classification system for ice from first-year ridges. 78% of all samples contained mixed ice with various compounds of brecciated columnar and granular ice. Ice strength of mixed ice showed isotropy, except for the samples containing mainly columnar ice crystals. For horizontal loading, mixed ice was stronger than columnar and granular ice. The residual strength of ductile ice depended on the strain rate. At 1.5% strain remained 70% of peak strength at 10−4 s−1 and 50% at 10−3 s−1. Ductile failure dominated for 75% of all mixed ice tests at 10−3 s−1 and − 10 °C. Ductile compressive strength was generally higher than brittle compressive strength for mixed ice. Brine volume was the main parameter influencing the tensile strength of the mixed ice which was between 0.14 MPa and 0.78 MPa measured at constant ice temperature of −10 °C.
|
|
| 16. |
- Casselgren, Johan, et al.
(författare)
-
Investigation of ice surface change during vehicle testing
- 2014
-
Ingår i: International Journal of Vehicle Systems Modelling and Testing. - 1745-6436 .- 1745-6444. ; 9:2, s. 137-150
-
Tidskriftsartikel (refereegranskat)abstract
- Today, there are a lot of vehicles and tyre testing carried out on lake ice surfaces. Thus, it is important to have knowledge about parameters that affect roadgrip. The thesis within this paper is that the liquid like layer which appears due to increasing temperature can be reduced by manipulating the ice roughness. This in turn should decrease the temperature dependence of the roadgrip in temperatures around 0°C. In order to investigate this, measurements of temperature, surface roughness and hardness and roadgrip were performed on three outdoor ice surfaces using an IR thermometer, an optical sensor with three IR-diodes, a steel ball drop indentation test and an RT3 curve, respectively. Additional ice roughness measurements were also made on two tempered ice surfaces in an ice hall. Results show a clear connection between ice temperature and roadgrip, unfortunately the created ice roughness was too small to influence the change in roadgrip
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
- Dempsey, John P., et al.
(författare)
-
Cleavage fracture of warm brackish ice
- 2013
-
Ingår i: Proceedings of the International Conference on Port and Ocean Engineering under Arctic Conditions.
-
Konferensbidrag (refereegranskat)abstract
- Two sets of cleavage (cracking parallel to the ice surface) fracture toughness tests were conducted at the Hamburg Ship Model Basin (HSVA) on brackish ice harvested from two separate locations in the Gulf of Bothnia. The ice was split using a pin-loaded compact tension geometry. The fracture tests were accompanied by tensile and compressive tests. This paper discusses the experiments and the results.
|
|
| 20. |
|
|
| 21. |
- Domaschuk, L., et al.
(författare)
-
Reactive soil pressures along pile in frozen sand
- 1991
-
Ingår i: Journal of cold regions engineering. - 0887-381X .- 1943-5495. ; 5:4, s. 174-194
-
Tidskriftsartikel (refereegranskat)abstract
- A multistage, lateral, pile-load creep test is carried out in a frozen sand maintained at -3° C. The pile is a tubular pipe, 150 mm square and 1,800 mm long. A series of plate load cells is mounted along the primary bearing face of the pile. Application of lateral loads of 35, 65, and 115 kN result in attenuating creep, whereas a lateral load of 145 kN leads to accelerating creep. The immediate components of pile displacement increase approximately linearly with applied load, while the creep components increase exponentially. Generally, the soil reaction forces near the ground surface decrease as the result of pile creep, and those further down the pile increase. Moduli of horizontal subgrade reaction computed on the basis of the measured soil reaction forces and the pile displacement are found to vary with applied pressure and creep. Magnitudes based on immediate displacements range from 1 to 7.5 GN/m3, while those based on total displacements range from 0.3 to 2 GN/m3.
|
|
| 22. |
- Eklund, Daniel, 1984-, et al.
(författare)
-
Vitamin D enhances IL-1β secretion and restricts growth of Mycobacterium tuberculosis in macrophages from TB patients
- 2013
-
Ingår i: International journal of mycobacteriology. - Netherlands : Wolters Kluwer. - 2212-5531. ; 2:1, s. 18-25
-
Tidskriftsartikel (refereegranskat)abstract
- The emergence of multidrug-resistant strains of Mycobacterium tuberculosis (MTB), the bacterium responsible for tuberculosis (TB), has rekindled the interest in the role of nutritional supplementation of micronutrients, such as vitamin D, as adjuvant treatment. Here, the growth of virulent MTB in macrophages obtained from the peripheral blood of patients with and without TB was studied. The H37Rv strain genetically modified to express Vibrio harveyi luciferase was used to determine the growth of MTB by luminometry in the human monocyte-derived macrophages (hMDMs) from study subjects. Determination of cytokine levels in culture supernatants was performed using a flow cytometry-based bead array technique. No differences in intracellular growth of MTB were observed between the different study groups. However, stimulation with 100nM 1,25-dihydroxyvitamin D significantly enhanced the capacity of hMDMs isolated from TB patients to control the infection. This effect was not observed in hMDMs from the other groups. The interleukin (IL)-1β and IL-10 release by hMDMs was clearly increased upon stimulation with 1,25-dihydroxyvitamin D. Furthermore, the 1,25-dihydroxyvitamin D stimulation also led to elevated levels of TNF-α (tumor necrosis factor-alpha) and IL-12p40. It was concluded that vitamin D triggers an inflammatory response in human macrophages with enhanced secretion of cytokines, as well as enhancing the capacity of hMDMs from patients with active TB to restrict mycobacterial growth.
|
|
| 23. |
- Engström, Niclas, et al.
(författare)
-
Direct low lateral slip roadgrip measurement compared with surface reflection of three laser beams
- 2010
-
Konferensbidrag (refereegranskat)abstract
- Road grip on roads depend on many factors and different techniques are available to estimate available road grip. To ensure that entrepreneurs have successfully restored the road grip to an acceptable level both entrepreneurs and road keepers need tools to evaluate present road grip. Information about road grip can also be utilized directly in a vehicle if available, for systems such as ABS, traction control, etc. To evaluate a non-contact method based on three laser beams with different frequency this equipment was mounted on a car equipped with a fifth wheel behind the car. The wheel is angled about 1.5 degrees compared with the centreline of travel. A force sensor in the hub measures forces acting on a standard winter tire also mounted to the hub, this is considered to be one measurement of road grip. The main reason is to see how well one can estimate road grip with a low cost non contact device made with Laser beams in combination with a photodiode.
|
|
| 24. |
|
|
| 25. |
- Engström, Niclas, et al.
(författare)
-
Discrepancies between longitudinal high slip and lateral low slip friction measurements on prepared ice surfaces
- 2009
-
Ingår i: Compendium of papers DVD, TRB 88th annual meeting. - Washington, DC : TRB.
-
Konferensbidrag (refereegranskat)abstract
- The Swedish road administration requested that an independent organization facilitate friction tests with several types of friction measuring devices. These tests were done on the following three surfaces: macro rough and micro smooth ice, macro- and micro smooth ice and macroand micro rough ice. The objective was to evaluate lateral low slip measuring devices against traditional longitudinal high slip devices. This was done by evaluating how they measure road grip, i.e. friction differences between road surfaces and the measuring tire. Tests were performed on Lake Kakel near Arjeplog, northern Sweden on March 18th, 2008. Weather conditions were stable with ice temperatures between -4°C (24.8°F) and -3°C (26.6°F). Tests showed that changes on the ice surfaces were readily detected with all four of the lateral low slip friction measurement devices and the two longitudinal high slip devices. Friction resolutions were higher with low lateral slip devices compared to high longitudinal slip devices. The tires on the devices were of different types and are the main reason for the difference in friction resolution. One major difference was detected; the lateral low slip method measured higher friction between its regular winter tire and the macro rough, micro smooth surfacecompared to the friction on the macro- and micro rough ice. Longitudinal high slip devices measured higher friction between its industrial friction tire and macro- and micro rough ice. Capacity to measure friction in curves was only displayed by the high longitudinal slip devices.
|
|
| 26. |
- Engström, Niclas, et al.
(författare)
-
Road grip test in Arjeplog
- 2008
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish road administration sees a need to improve the road grip estimation capacity for the Swedish road system. The challenge is to find methods to measure road grip fast and reliable. There where six different system types at the tests in Arjeplog, three continuous, two system measuring road grip through deceleration and one system based on GPS and accelerometers. Two system types used air craft runway tires. The other systems used either studded winter tires or friction winter tires. Test runs where performed and road grip where recorded for three different surface types, old system 2000 ice, polished ice and new system 2000 ice. Weather data was collected during the three days. It is clear that all systems can detect changes in road grip. It is clear that continuous systems hold an information advantage over the sequence oriented systems. For measurements of road grip on winter roads, we recommend that rubber compounds adapted for cold conditions are used, as the resolution of the road grip measurement where better. In extreme condition like on polished ice, studded winter tires increase the road grip significantly.
|
|
| 27. |
- Engström, Niclas, et al.
(författare)
-
Stop distances for ten studless winter tires
- 2009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport innehåller stoppsträckor för tio omgångar dubbfria vinterdäck. Arbetets huvudmål är att kunna skapa en grund för vinterdäcksklassificering. Så småning om skall traffikanter kunna få relevant information om olika däckens förmåga att skapa tillräckligt väggrepp på farliga vinterväglag. Vägverket ser ett ökat behov av kunskap då dubbdäcksanvändandet kommer att minskas i framtiden.
|
|
| 28. |
|
|
| 29. |
- Fransson, Eva, 1967, et al.
(författare)
-
The Abdoul-Rauzy-Peneloux Group Contribution Equation of State Extended to CFC-Containing Mixtures
- 1993
-
Ingår i: Chemical Engineering Science. ; 48:10, s. 1753-1759
-
Tidskriftsartikel (refereegranskat)abstract
- This study contributes to the development of new thermodynamic models, useful for the prediction of refrigerant-mixture properties. Mixtures are considered to be potential substitutes for the environmentally harmful chlorofluorocarbons. Here the Abdoul—Rauzy—Pénéloux (ARP) equation of state (EOs) is used, which combines a group contribution excess Helmholz energy model with traditional cubic EOSs. This EOS, initially developed for different petroleum mixtures, has been extended to cover also certain compounds containing chlorine and fluorine. A predictive method for PVT modelling of mixtures containing CFCs, HCFCs, HFCs, FCs and hydrocarbons has thus been developed. From experimental data for 31 different binary systems, 19 general group parameters were estimated. the error on the calculated vapor pressure for these systems does not exceed 5.1% for any of the considered mixtures. This demonstrates the effectiveness of the method since the traditional mixing rules would have demanded 31 specific interaction parameters to describe the same number of systems, without the possibility of extending their validity to other mixtures. In order to verify the predicting capacity of the method, it has also been applied to a ternary and an azeotropic system, that have not been included in the estimation procedure of the parameters. The results from these applications are deviations on the calculated pressure of 0.7 and 26% for the ternary and the azeotropic system, respectively.
|
|
| 30. |
- Fransson, Lennart, et al.
(författare)
-
A statistical approach to extreme ice loads on lighthouse Norströmsgrund
- 2006
-
Ingår i: Proceedings of the 25th International Conference on Offshore Mechanics and Arctic Engineering. - New York : American Society of Mechanical Engineers. - 791837777 ; , s. 773-782
-
Konferensbidrag (refereegranskat)abstract
- Data from full-scale measurements of ice loads on lighthouse Norströmsgrund has been analyzed using basic statistical methods. Questions like scaling, duration of ice interaction and correlation of extreme ice loads on different segments of the structure are discussed. Typical ice conditions in the Baltic Sea are described in general and the region is divided into areas with similar ice and ice movements. Indications of strong influence of structure diameter on the effective ice pressure were confirmed by results obtained on other lighthouses in the area. The result can be used in simulations of ice load probabilities for fixed vertical structures with small diameters located in the Baltic Sea.
|
|
| 31. |
|
|
| 32. |
- Fransson, Lennart, et al.
(författare)
-
Brash ice shear properties : laboratory tests
- 1985
-
Ingår i: POAC 85. - Hørsholm : Dansk hydraulisk institut. - 8798195018
-
Konferensbidrag (refereegranskat)abstract
- According to earlier studies of brash ice covered channels and problems connected with winter navigation laboratory tests have been performed, treating brash ice as a Mohr-Coulomb material cohesion and shear properties have been studied. A shear box, 0. 5 multiplied by 0. 5 m, equipped with a water bag for normal loading, was used. The force required to shear the rubble was determined as a function of normal force, shear rate and ice piece thickness. The test results are analyzed and presented. The results are also compared with results from other studies and the applicability is discussed
|
|
| 33. |
|
|
| 34. |
|
|
| 35. |
- Fransson, Lennart
(författare)
-
Do cracks reduce thermal ice stresses?
- 1991
-
Ingår i: Ice-Structure-Interaction. - : Encyclopedia of Global Archaeology/Springer Verlag. - 3540521925 ; , s. 423-435
-
Konferensbidrag (refereegranskat)
|
|
| 36. |
- Fransson, Lennart, et al.
(författare)
-
Experimental investigation of friction coefficient of laboratory ice
- 2011
-
Ingår i: Proceedings of the 21st International Conference on Port and Ocean Engineering under Arctic Conditions.
-
Konferensbidrag (refereegranskat)abstract
- Friction processes of rubber on ice, steel on ice and ice on ice have been investigated bymeasuring contact forces in controlled laboratory experiments. A carefully prepared ice platewas rotated at a constant speed and brought into contact with a ring on which torque andnormal load was measured. Replicas of the different types of standardized ice surfaces werestudied in microscope. Friction of rubber on ice reached a maximum value at a sliding speedof abt. 100 mm/min. At a temperature of -10°C this maximum friction coefficient decreasedwith increasing ice surface roughness. Friction of steel on ice increased with decreasing speedand no maximum value was obtained. Ice sliding on ice at low speed resulted in high frictionforces when sintering took place.
|
|
| 37. |
|
|
| 38. |
|
|
| 39. |
- Fransson, Lennart
(författare)
-
Gjutning av isbanor för biltestning
- 1992
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The effect of limestone and surfactants on thin superimposed ice layers have been examined. The ice quallity is in high extent dependent on the amount and size of encapsulated air bubbles. In laboratory tests a small amount of an anionic surfactant seemed to reduce the production of gasbubbles during freezing. Reduction of porosity in the ice was also obtained by decreasing the air content in the water but this may be somewhat unpractical. White limestone mixed with water showed two positive effects. The water froze faster and the ice became whiter. The whiter ice surface reflected more solar radiation which helps to protect the ground underneeth from heat. Sudden heating of a thick ice cover caused thermal cracking. Therefore it can be recommended that the ice surface in cold weather is sprayed with a fine moisture before flooding.
|
|
| 40. |
- Fransson, Lennart
(författare)
-
Ice force measurements on a bridge pier in the Lule river
- 1983
-
Ingår i: VTT Symposium (Valtion Teknillinen Tutkimuskeskus). - Espoo : Valtion teknillinen tutkimuskeskus. Tie- ja liikennelaboratorio. - 951381873X ; , s. 759-769
-
Konferensbidrag (refereegranskat)
|
|
| 41. |
- Fransson, Lennart, et al.
(författare)
-
Ice loads for wind-power foundations in the Gulf of Bothnia
- 2009
-
Ingår i: Proceedings of the 20th International Conference on Port and Ocean Engineering under Arctic Conditions. ; June 9-12, 2009, s. 12-19
-
Konferensbidrag (refereegranskat)abstract
- Ice loads measured on lighthouses in the Gulf of Bothnia can serve as guidance for design of foundations for wind-power generators. At some locations in the sea these structures must withstand high pressure from solid land fast ice as well as from ridges or other compacted ice masses that are drifting. Recommendations for design of offshore foundations around the Swedish coastline have recently been written by the authors. For the purpose of design, effective pressure as well as compressive strength is assumed to be independent of ice thickness. All structures should be designed for dynamic ice loads that are dependent on the natural frequency of the structure and the ice drift velocity. Increased effective pressure has earlier been indicated for high speed ice crushing both in field studies and compression tests. The presented results from ice load measurements on lighthouse Norströmsgrund support the suspicion that also design ice loads should increase with drift speed. This rate effect and other uncertainties about the worst case scenario for ice-induced vibrations suggest a more conservative design of wind-power foundations inside the dynamic ice zone.
|
|
| 42. |
|
|
| 43. |
- Fransson, Lennart
(författare)
-
Isen som arbetsplats
- 1994
-
Ingår i: Bygga framtid. ; 5, s. 22-23
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
|
| 44. |
- Fransson, Lennart
(författare)
-
Ishandboken
- 1994
-
Rapport (populärvet., debatt m.m.)
|
|
| 45. |
|
|
| 46. |
|
|
| 47. |
|
|
| 48. |
- Fransson, Lennart
(författare)
-
Load bearing capacity of an ice cover subjected to concentrated loads
- 1985
-
Ingår i: Proceedings of the Fourth International Offshore Mechanics and Arctic Engineering Symposium. - New York : American Society of Mechanical Engineers. ; , s. 170-176
-
Konferensbidrag (refereegranskat)abstract
- This work presents theoretical and field investigations of the bearing capacity of floating ice covers subjected to concentrated loads. The field tests were performed in the Gulf of Bothnia on columnar sea-ice with low salinity and with a thickness of 0. 4-0. 8 m. Thick plates with vertical anisotropy such as the tested ice covers have shown large local shear deformations and nonlinear creep. An empirical model is presented for the prediction of deflections based on curve fitting where these facts are taken into account. A modified strain-energy criteria or a local puncing are assumed to govern the failure. The failure load as a function of ice thickness and loading rate is plotted for a certain ice type. The bearing capacity of reinforced ice covers is compared with natural ice and the effect of different reinforcements such as wooden bars is discussed
|
|
| 49. |
|
|
| 50. |
|
|
