Dissertations / Theses: 'Ice'

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Sukhorukov, Sergiy. "Ice-Ice and Ice-Steel Friction in Field and in Laboratory." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23559.

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Friction is one of the key phenomena during the interaction of ice with offshore structures and ships, ice rafting and ridging processes, and the brittle compressive failure of ice. Therefore, knowledge of the ice friction laws and a better understanding of this phenomenon are needed for the design of safe and reliable offshore structures and successful operations in ice-infested waters. This thesis presents experimental studies on ice friction in the field and in the laboratory and can be divided into three parts: field study of ice friction and the effects of different parameters on the kinetic and static friction coefficients; investigation of geometrical stick-slip interaction between ice and stainless steel in small-scale laboratory tests; field investigation of the vertical ice forces exerted on isolated vertical piles frozen in a level sea due to changes in the water level. The first version of the experimental setup for the field tests to study ice friction was relatively simple and was used only in 2010. Significant modifications and improvements were made to the setup in 2011 that allowed us to better control the test conditions (i.e., velocity, normal load). The available range of sliding velocities (between 6 mm s-1 and 43 mm s-1) did not cover the whole range of our interest. Therefore, a new pulling mechanism was introduced in the tests in 2012 that allowed us to extend the sliding range up to 110 mm s-1. The field experiments were conducted with first year sea ice in the Barents Sea and in fjords at Spitsbergen during three springs (2010-2012). In September of 2012, the ice friction tests were performed with multiyear sea ice northeast of Greenland. Most of the tests were performed to investigate the friction between sea ice and sea ice, while the rest were to study the friction between sea ice and corroded steel. The aim of the study was to survey the most important factors that affect ice friction in field conditions and to determine whether the existing friction models correctly predict the dependences observed in the field tests. The effects of the sliding velocity (6 mm s-1to 105 mm s-1), air temperatures (-2°C to -20°C), normal load (300 N to 2000 N), presence of sea water in the interface, and ice grain orientation with respect to the sliding direction on the friction coefficient were investigated. The effect of the hold time on the static friction coefficient was also studied. The test campaigns showed that ice surface roughness is likely to be the most important parameter in determining the friction coefficient. Repeated sliding over the same track led to surface polishing and decreased the kinetic friction coefficient from 0.48 to 0.05. When sliding occurs between unsmoothed surfaces, the friction coefficient was found to be independent of the sliding velocity. As the contacting surfaces become smoother, the kinetic friction coefficient begins to depend on the velocity, as predicted by existing ice friction models. Some attempts were made to characterise ice surface irregularities and real contact area using two techniques: 1) the production of an ice surface cast and its further analysis using an optical microscope and 2) measurements of the pressure distribution and real contact area using tactile sensors. The static friction coefficient increases logarithmically with the hold time and changes from approximately 0.6 at 5 s to 1.26 at 960 s. The small-scale laboratory studies on the stick-slip interaction between ice and stainless steel were performed at the University Centre in Svalbard (UNIS). A specially designed device allowed us to study the effect of well controlled steel surface roughness on the interaction between ice and steel under various test conditions. The effects of the relative sliding rate (1.67 × 10-6 m s-1 to 0.83 × 10-3 m s-1), temperature (-5°C to -25°C) and applied constant pushing force were also investigated. Stick-slip interaction was always observed in the tests on samples with an arithmetic average roughness (Ra) between 2 μm and 15 μm. Both steady state sliding and stick-slip were observed in the tests on samples with the lowest (Ra = 2 μm) and the highest (Ra = 25.2 μm) roughness. The slip distance was found to be equal to the mean pitch profile (mean profile wavelength) for all velocities studied. The elasticity of the ice was found to be an important factor in the stick-slip interaction. The field studies of the vertical ice forces exerted on isolated vertical piles frozen in the ice were performed in Svea, Spitsbergen, in March of 2010. Four different piles made of steel and aluminium were used in the experiments. The piles were pushed through the ice using a hydraulic jack. The first peak load measured in the tests is associated with the onset of the ice-pile relative movement. Because we always observed failure at or very near the ice-pile interface, the first peak load can be treated as the strength of adhesion or the cohesive failure of ice in the vicinity of the interface. Elastic plate theory was used to estimate theoretically the vertical forces exerted on a pile.

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Howe, Rachel. "Ice XI : the ordered form of ICE Ih." Thesis, University of Birmingham, 1988. http://etheses.bham.ac.uk//id/eprint/5255/.

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The history of the development of the understanding of the statistical arrangement of hydrogen bonds in ice Ih and the discovery of the transition at 72 K to the ordered phase, ice XI, catalysed by alkali hydroxide doping, is reviewed. Possible ordered arrangements of hydrogen bonds are discussed and enumerated. A theory is presented relating the entropy and permittivity of partially ordered ice to the degree of order. The apparatus developed for dielectric experiments on KOH-doped ice is described. The results of such measurements for polycrystalline specimens and one single crystal are presented. Measurements above the transition reveal that the main charge carriers are OH$^-$ ions, with a temperature-independent mobility of approximately 10$^-$$^1$$^0$ m$^2$ v$^-$$^1$ s$^-$$^1$. The transformation to the ordered phase starts when the sample is cooled below about 65 K, and once started can be speeded up by heating the sample to 67-70 K: the static permittivity and the a.c. conductivity slowly decrease. Neutron powder diffraction experiments were performed on HRDP at ISIS. After one unsuccessful experiment, dielectric measurements on powder samples showed the importance of excluding CO$_2$ during preparation. In a second experiment the structure of ice XI was confirmed and the lattice parameters determined for the first time.

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Andersson, Lars-Olof. "Ice accretion and ice adhesion to polymer material." Licentiate thesis, Luleå tekniska universitet, 1993. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26519.

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Gripenvik, Christian. "Is/Ice." Thesis, Linnéuniversitetet, Institutionen för film och litteratur (IFL), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-95589.

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Romanen ”Is” utspelar sig i en fiktiv framtid och skildrar ett Sverige i svallvågorna avklimatförändringarna. Landet styrs av auktoritära högerpartier som har infört strikt kontrollpå befolkningstillväxten genom att unga män steriliseras efter att ha donerat spermaoch senare i livet får ansöka om att skaffa barn.Inom ramen för det här arbetet skildras samhället ur två perspektiv:1. Chinua kommer som flykting till Sverige och försöker starta ett nytt liv, men möterhårt motstånd från både samhällsapparaten och befolkningen. I desperation tvingashan sälja sin kropp, eller snarare sina spermier, till barnlösa kvinnor.2. I det inhägnade samhället Gränna bor Arwen och Viggo. De har fyra barn och ärbåda högt uppsatta i samhällsadministrationen och näringslivet. Arwen är den mest karriärmässigtdrivna, medan Viggo känner sig mer utanför. Skillnaderna mellan dem växeri takt med att samhället radikaliseras och de driver sakta isär, samtidigt som de vinnläggersig om att upprätthålla en polerad fasad.Syftet är att skildra ett framtida Sverige ur flera perspektiv så att möjliga svagheteroch styrkor visas upp. Chinuas perspektiv utgår från positionen ”ute, vill in”, en personsom utan eget förskyllande befinner sig utanför gemenskapen och kämpar för att bli endel av den. Chinua har tidigare försökt hitta en plats i andra europeiska länder, menmisslyckats och därför tagit sig vidare till Sverige. Arwen och Viggo-perspektivet äristället ”inne, vill vara kvar”, vilket ger möjlighet att gestalta den styrande delen av samhället,där de som passar in och tror på systemet lever.Planen är att i framtiden utöka romanen med ytterligare två perspektiv: ett om detbarndrömmande paret Jani och Dani, som får avslag på sin ansökan om att skaffa barn(också ett ”inne, vill vara kvar”-perspektiv, men underifrån); ett om de som valt att lämnadet nya Sverige och försöka bygga en alternativ gemenskap längre norrut (”ute, villvara ute”). Inom de respektive perspektiven är det också meningen att det ska finnas nyanseroch glidningar, och centrala personer kommer att skifta tillhörighet.Till planen hör också att vidareutveckla världsbygget med centrala frågor som temperaturhöjningoch havsnivåhöjning och deras bredare konsekvenser, samt att utforskaframtida teknisk utveckling och dess effekter på samhället och hur människor umgås.

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Horgan, Huw J. Anandakrishnan Sridhar. "Geophysical observations of polar ice sheets and ice shelves." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4587/index.html.

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Berg, Niklas. "Ice navigation with ice compressionin the Gulf of Finland." Thesis, Uppsala University, Division of Systems and Control, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-131133.

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Safe winter navigation is a hot topic. Not only is the traffic density increasing but theenvironmental considerations are also getting bigger. An oil leakage from a big oiltanker can be of catastrophic proportions in the wrong area and more trafficincreases the risk of an accident. A project that aims for safer winter navigation isSafeWIN. The aim of this project is to develop a forecasting system for compressiveice and thus make winter navigation safer.This thesis is part of above mentioned project and aims to investigate what influenceice compression and ice class has on winter navigation. Vessels are exclusivelyAFRAMAX size tankers sailing on Primorsk in the Gulf of Finland during 2006. Transitdata comes from AIS tracks recorded by the Swedish Maritime Administration. Adatabase with tanker transits has been created and this information is the source forthe studies in this thesis. Included in the database are wind data, ice particulars andtransit information such as speed, and time at different activities during the transit.Average values for a transit has been investigated for comparison and to get a pictureof an average transit.Velocity, waiting time and time with assisting icebreaker are parameters that arebelieved to show how a tanker performs in winter navigation. These parameters arecompared with ice compression and ice class separately to see if there is acorrelation. Ice compression has also been investigated for correlation towards windforce to see if stronger wind generates stronger compression.Using the velocity in different ice compressions an estimate of ice resistance that stemfrom ice compression has been extracted by means of Lindqvist’s formula.

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Lopes, Inês Marques. "Ice cream and nutrition: modeling optimal ice cream formulations." Master's thesis, ISA, 2014. http://hdl.handle.net/10400.5/6779.

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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
It is becoming more urgent for producers to design new products that follow the consumer’s trends and expectations, such as, “low fat”, “no sugars” or “low calorie” products, while maintaining the ice cream features. The aim of this thesis was to develop a computer aided-tool, based on a mathematical model that helps to design ice cream recipes. By combining different expertise information, a linear programming model has been developed with the objective of minimizing the recipes calorie content. It compiles information about ingredients that are commonly used in ice cream manufacture and their contribution to nutrient and processing constraints. After setting all requirement constraints for each specific ice cream, the Excel Solver optimization tool, gives a solution for the model establishing the ingredients and their quantities to be included in the recipe. The developed model can be easily updated to account for changes in market demands or production conditions. It was created a version of the model for each one of the following ice cream types: water ice, ice cream, milk ice, dairy ice, sorbet and artisanal recipe. In order to test the effectiveness of the model, seven innovative recipes, using Portuguese ingredients with healthy benefits, have been created and tested at DuPont, Denmark.

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Jordan, James. "Modelling ice-ocean interactions in and around ice shelves." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/28616.

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Physical processes in Antarctica and the Southern Ocean are of great importance to the global climate system. This thesis considers two such processes, namely ice- ocean interaction in ice shelf basal crevasses and the conditional instability of frazil ice growth. It has been suggested that freezing within basal crevasses can act as a stabilising in uence on ice shelves, preventing their break up. Using Fluidity, a nite element ocean model, it is found that ocean circulation within a crevasse is highly dependent upon the amount of freezing in the crevasse. It is also found that frazil ice formation is responsible for the vast majority of freezing within a crevasse, and that there is a non linear relationship between the amount of supercooling in a crevasse and its freeze rate. The conditional instability of frazil ice growth is a little investigated mechanism of ice growth. Any frazil forming in the water column reduces the bulk density of a parcel of frazil-seawater mixture, causing it to rise. Due to the pressure-decrease in the freezing point, this causes more frazil to form, causing the parcel to accelerate, and so on. Numerical modelling nds that the instability does not operate in the presence of strong strati cation, high thermal driving (warm water), a small initial perturbation, high 'background' mixing or the prevalence of large frazil ice crystals. Given a large enough initial perturbation this instability could allow signi cant rates of ice growth even in water that is above the freezing point. The research presented in this thesis forms the material for two peer-reviewed publi- cations; 'Modelling ice ocean interactions in ice shelf basal crevasses' (Jordan et al., 2014) and 'On the conditional frazil ice instability in seawater' (Jordan et al., 2015).

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Rosier, Sebastian H. R. "The interaction between tides, ice shelves and ice streams." Thesis, Bangor University, 2015. https://research.bangor.ac.uk/portal/en/theses/the-interaction-between-tides-ice-shelves-and-ice-streams(0590227d-ae56-4a4d-8e5b-302bbe768774).html.

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Observation of ice-stream and ice-shelf flow has revealed interaction with the ocean tide, in some cases far upstream of the grounding line. Ice-stream velocities can be greatly affected by local ocean tides at a variety of timescales but of particular interest is a fortnightly modulation in flow that has been observed on the Rutford Ice Stream. This frequency is absent in the forcing, far stronger than the dominant tidal constituent signals and has been observed far inland. Understanding what mechanism can produce this signal can provide a window into mechanisms at the base of the ice stream that affect its flow. A consequence of this nonlinearity is that the mean flow of the Rutford Ice Stream is increased in comparison to a situation where no tidal forcing is present, implying that changes in tides could alter the long term flow of ice from Antarctica. Since local tides are sensitive to bathymetry which can change drastically due to changes in ice-shelf geometry and grounding line position, a feedback exists between tides and the ice sheet whereby changes in the flow of ice could alter tides which in turn would change the ice velocity. This thesis presents results from both ice-stream/shelf and tidal models to investigate these two mechanisms. Firstly a nonlinear 3D viscoelastic full-Stokes finite element model explores possible sources of nonlinearity that can produce fortnightly modulation in ice-stream flow far upstream of the grounding line. This model looks at stress transmission, grounding zone flexure, hydrology and grounding line migration and the conclusion is that tidally-induced changes in the subglacial water pressure play the largest role in producing this effect. Then, the OTIS tidal model is used to demonstrate that reduction in the thickness and/or extent of ice-shelves, in particular the Filchner-Ronne ice shelf, could greatly impact both tidal amplitudes and dissipation rates in the region. The research in this thesis clearly shows the importance of tidal interactions with the Antarctic ice sheet and that these are not limited to short temporal timescales.

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Shafrova, Svetlana. "First-year sea ice features. Investigation of ice field strength heterogeneity and modelling of ice rubble behaviour." Doctoral thesis, Norwegian University of Science and Technology, Department of Civil and Transport Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1919.

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For the nearest years the design load level for offshore structures in Arctic regions is likely to be controlled by first-year sea ice ridges and rubble fields if the icebergs are not present in the area. Drifting ridges may hit fixed or moored surface structure such as platforms or ships, or they may gouge the seabed endangering pipelines and wellheads. Both the temporal and spatial properties of the consolidated layer and the unconsolidated part (the ice rubble) of the ice ridge are important input into ridgeload models. A better understanding of the ice rubble behaviour will enable us to determine the ice-ridge load more accurately. This thesis deals with two separate but connected subjects, namely: the ice strength field heterogeneity of both first-year sea ice ridge and level ice and the mechanical behaviour of the ice rubble.

Field mechanical testing of first-year sea ice by uniaxial compression has been done in order to improve the knowledge of the ice fields strength heterogeneity. The inplane ice strength non-homogeneity of different ice fields on the landfast level ice in the Spitsbergen fjords were investigated. A typical ice strength variability was found to be about 20-40% for the vertical ice samples and 10-20% for the horizontal ones. The weak zones were found within the entire ice fields. It was established that the strength of the ice samples taken from a certain depth from the ice cover surface at the different locations of the same ice field varied by a factor of 3 to 4. Furthermore, two first-year sea ice ridges have been examined with respect to the 2D spatial strength distribution: one in the North-western Barents Sea and one in the Arctic Ocean nearby Spitsbergen. The ice ridges are characterized by high strength heterogeneity of 40-55%, where the ice strength varied more than 3 times along both vertical and horizontal directions.

Special Finite Difference program “Inhomogeneity” was used to study the influence of the ice strength heterogeneity on the ice loads. It was shown that the ice heterogeneity might be one of the reasons for the scale effect.

In order to investigate the nature of freeze bonds between the ice blocks, series of field and laboratory small scale tests were conducted with submerged ice blocks. The small scale field tests were carried out in Adventfjorden on Spitsbergen. An opening was made in the landfast level ice. The level ice was sawed into cubic blocks which then were submerged down into the water. Some of the ice blocks were cut in two parts and then frozen together in order to simulate the freeze bonds between the ice blocks. The other blocks were submerged without forming the adfreeze bond. In addition to that, laboratory tests with both artificial ice (fresh and sea water) and natural sea ice were conducted in the cold laboratories at the University Centre in Svalbard (UNIS). The temporal development of the freeze bonding strength and the local strength of the ice blocks in the ice rubble, their changes with block size, confinement and ice properties were studied. The average freeze bonding strength from the field tests was found as 32 ± 18 kPa after 48 hours of submerging. The corresponding freeze bonding strength from the laboratory tests was 67 ± 52 kPa for the natural sea ice and 274 ± 142 kPa for the artificial freshwater ice within 60 hours of testing. Moreover, the ratio of freeze bonding strength to the strength of the submerged ice was found in the range of 0.008 to 0.082 with an average around 0.03 after 48 hours of submerging in the field. The corresponding strength ratio varied from 0.14 to 0.38 for the artificial fresh water ice and from 0.015 to 0.40 for the sea ice within 60 hours of testing in the laboratory.

A pseudo-discrete continuum model has been developed to study the behaviour of the ice rubble and in particularly its initial failure mechanism that is associated with the breakage of the freeze bonding contacts (rubble skeleton). The model is a combination of discrete particle assembly generation and Finite Element analysis of this assembly. The model provides a possibility to simulate the contacts between the ice blocks. A parametric analysis simulating 2D direct shear tests shows that the pseudo-discrete continuum model is very sensitive to both strength and morphology of the freeze bonds between the ice blocks. An attempt to extend the model to study large deformations within the ice rubble (that is associated with rotation, rearrangement of the ice blocks and their breakage) was considered.

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Rice, Mark Stewart. "Examining the relationship between off-ice testing and on-ice performance in male youth ice hockey players." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55151.

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Background: In an elite sport setting, physical assessments are administered for talent selection purposes, as well as for continuous monitoring to ensure the effective implementation of training methods to reach optimal sport performance. Physical assessment allows coaches and trainers to determine where an athlete ranks compared to other players, as well as to identify the strengths and weaknesses of the individual. In ice hockey, research has focused on high performance players (e.g., NHL prospects) and the physical characteristics that they possess. To date, the early assessment of youth minor hockey players, and the relationship between off-ice and on-ice performance has received little attention. Purpose: The purpose of this investigation was to examine the relationship between off-ice physical fitness performance and sport-related performance on on-ice assessments in male, minor ice hockey players. Methods: Eleven male minor hockey players were recruited across three birth years (2004, 2005, and 2006). Participants completed a battery of 14 off-ice testing protocols that measured body composition, musculoskeletal fitness, aerobic fitness, and anaerobic fitness, as well as 4 on-ice protocols that measured skating speed, skating agility, skating acceleration, and shot velocity. Results: Older players were taller and heavier than the younger players, and defensemen were taller and heavier when compared to forwards. Across participants, standing long jump was positively correlated to all skating tests (i.e., speed, agility, and acceleration). Players who jumped further demonstrated significantly greater on-ice skating performance. Significant correlations were also found between player weight and maximum speed, agility, and shot velocity. Lighter players were faster and more agile on the ice, while players with a greater mass demonstrated higher scores in shot velocity. A significant relationship was also found between push-ups and off-ice sprinting capability. Conclusion: These findings were consistent with high performance research with adults revealing that physical measures (such as standing long jump) may have predictive value for on-ice performance even in young, pre-pubertal ice hockey players. While such measures may contribute to the successful identification and selection of players for high performance, utilizing such assessments also has important training implications for the long-term development and performance of all players.
Education, Faculty of
Kinesiology, School of
Graduate

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Fried, Mason. "Grounding Zone Process| Ice Mechanics and Margin Lakes, Kamb Ice Stream and Whillans Ice Stream, West Antarctica." Thesis, Portland State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1542719.

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The lateral "corners" where Kamb and Whillans Ice Streams (KIS and WIS) discharge into the Ross Ice Shelf share common geometries and ice mechanical settings. At both corners of the now-stagnant KIS outlet, shear margins of apparently different ages confine regions with a relatively flat, smooth surface expression. These features are called the "Duckfoot" on the northern, right-lateral side and the "Goosefoot" on the other. It has been suggested, on evidence found in ice internal layers, that the flat ice terrains on KIS were afloat in the recent past, at a time when the ice stream grounding line was upstream of its present location. The overdeepening in the bed just upstream of the KIS grounding line supports this view of the past geometry.

The right-lateral margin at the outlet of the currently active WIS, the location of Subglacial Lake Englehardt (SLE), appears to have many similarities with the right lateral margin of KIS, though with a less developed looking inboard margin. This paper presents a mechanical analysis using surface and bed topography and velocity datasets comparing the Duckfoot flat ice terrain with the terrain around Subglacial Lake Englehardt. At both locations mechanical thinning along shear margins and lows in the bed topography redirects basal water routing towards the features. Here, I consider the history of these features and their role in ice stream variability by comparison of the relict and modern features and via numerical modeling of ice shelf grounding and ungrounding in response to variations in ice flow.

We propose two scenarios for the development of flat ice terrains/subglacial lakes at the outlets of ice streams. In the first, development of a lake in the hydraulic potential low along a shear margin forces a margin jump as shearing develops along the inboard shore of the margin lake. This thesis presents evidence for an inboard (relative to the main outboard shear margin) zone of shear along the inboard shoreline of SLE, suggesting that subglacial lakes along shear margins are capable of facilitating shear margin jumps. In the second, grounding line advance around a relative low in the bed, creating adjacent margins along the lakeshores, forms a remnant lake. Discerning which of these scenarios is appropriate at the KIS outlet has implications for understanding the history of the ice stream grounding line.

An ice flow model is used to place these local conditions in a regional context by studying the effect of internal perturbations, such as ice rise stagnation or inward margin jumps, on grounding line position. Bathymetry is important in determining ice stream flow in the ways that might not be otherwise realized in 1-D flow model studies. In the numerical modeling experiments, grounding line advance across the KIS outlet is mediated by the overdeepening in the bed and proceeds not in the direction of ice flow but transverse to flow. This finding adds complexity to both a flowline view of grounding line migration and the theory that grounding lines are unstable in the presence of inward sloping bed topography.

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Fried, Mason Joseph. "Grounding Zone Processes: Ice Mechanics and Margin Lakes, Kamb Ice Stream and Whillans Ice Stream, West Antarctica." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1112.

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The lateral "corners" where Kamb and Whillans Ice Streams (KIS and WIS) discharge into the Ross Ice Shelf share common geometries and ice mechanical settings. At both corners of the now-stagnant KIS outlet, shear margins of apparently different ages confine regions with a relatively flat, smooth surface expression. These features are called the "Duckfoot" on the northern, right-lateral side and the "Goosefoot" on the other. It has been suggested, on evidence found in ice internal layers, that the flat ice terrains on KIS were afloat in the recent past, at a time when the ice stream grounding line was upstream of its present location. The overdeepening in the bed just upstream of the KIS grounding line supports this view of the past geometry. The right-lateral margin at the outlet of the currently active WIS, the location of Subglacial Lake Englehardt (SLE), appears to have many similarities with the right lateral margin of KIS, though with a less developed looking inboard margin. This paper presents a mechanical analysis using surface and bed topography and velocity datasets comparing the Duckfoot flat ice terrain with the terrain around Subglacial Lake Englehardt. At both locations mechanical thinning along shear margins and lows in the bed topography redirects basal water routing towards the features. Here, I consider the history of these features and their role in ice stream variability by comparison of the relict and modern features and via numerical modeling of ice shelf grounding and ungrounding in response to variations in ice flow. We propose two scenarios for the development of flat ice terrains/subglacial lakes at the outlets of ice streams. In the first, development of a lake in the hydraulic potential low along a shear margin forces a margin jump as shearing develops along the inboard shore of the margin lake. This thesis presents evidence for an inboard (relative to the main outboard shear margin) zone of shear along the inboard shoreline of SLE, suggesting that subglacial lakes along shear margins are capable of facilitating shear margin jumps. In the second, grounding line advance around a relative low in the bed, creating adjacent margins along the lakeshores, forms a remnant lake. Discerning which of these scenarios is appropriate at the KIS outlet has implications for understanding the history of the ice stream grounding line. An ice flow model is used to place these local conditions in a regional context by studying the effect of internal perturbations, such as ice rise stagnation or inward margin jumps, on grounding line position. Bathymetry is important in determining ice stream flow in the ways that might not be otherwise realized in 1-D flow model studies. In the numerical modeling experiments, grounding line advance across the KIS outlet is mediated by the overdeepening in the bed and proceeds not in the direction of ice flow but transverse to flow. This finding adds complexity to both a flowline view of grounding line migration and the theory that grounding lines are unstable in the presence of inward sloping bed topography.

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De, Angelis Hernán. "Palaeo-ice streams in the north-eastern Laurentide Ice Sheet." Doctoral thesis, Stockholm University, Department of Physical Geography and Quaternary Geology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7116.

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This thesis presents a palaeoglaciological study aimed to determine the location, geometry and temporal evolution of palaeo-ice streams of the north-easternmost Laurentide Ice Sheet. The work was accomplished through the geomorphological interpretation of satellite imagery over 3.19 x 10⁶ km² of the Canadian Arctic, using a glaciological inversion scheme. Ice streams were active in this region during most of the time between the Last Glacial Maximum and the last deglaciation. A web of ice streams and inter-ice stream areas existed. Three major ice stream networks are identified: the M'Clintock Channel, Gulf of Boothia – Lancaster Sound and Hudson Strait. The M'Clintock Channel bears the most complex landform record, comprising three generations of palaeo-ice streams. Their location was weakly controlled by the subglacial topography and their geometry was determined by frozen-bed portions of the ice sheet, thus providing evidence for pure ice streams in the Laurentide Ice Sheet. In contrast, the more pronounced relief of the Gulf of Boothia – Lancaster Sound corridor supported topographically controlled ice streams. The landform record on emerged land along Hudson Strait is insufficient to support the existence of ice streams. It is therefore proposed that ice streams were constrained within the deep parts of the strait while flanked by cold-based zones on the margins. Small transient ice streams on Baffin and Prince of Wales islands drained local remnant ice caps during the collapse of the ice sheet. Analysis of the controls on the location and flow of palaeo-ice streams suggests that the interaction between the subglacial topography and thermal state of the substrate plays a more fundamental role than the geology. It is concluded that the behaviour of ice streams cannot be explained in terms of environmental controls alone, but the complex dynamics of ice stream shear margins and onset zones must be considered.

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Baldwin, Kylie. "Ice, ice, baby? : a sociological exploration of social egg freezing." Thesis, De Montfort University, 2016. http://hdl.handle.net/2086/13109.

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Social egg freezing is a fertility preservation strategy which enables women to preserve a number of healthy unfertilised eggs for potential future use when faced with the threat of age-related fertility decline. The overall aim of this thesis was to explore how women understand, construct and experience social egg freezing in the context of debates surrounding reproductive ‘choice’ and ‘delayed motherhood’. The study sought to provide insights into how women perceive the risks and benefits of social egg freezing, how it relates to their discourses of parenthood and their future reproductive intentions as well as how the ‘medical’ encounter in egg freezing is experienced. The thesis draws on Layder’s theory of social domains, selectively focusing on the domains of contextual resources, situated activity, and psychobiography to explore the macro and micro level aspects of social egg freezing (Layder 2006). Consistent with this theoretical framework, the study utilised a multi-method approach: a content and critical discourse analysis of UK newspaper articles on egg freezing, a demographic questionnaire, and semi-structured interviews with 31 users of egg freezing technology. ‘Career reasons’ were presented as the dominant motivation for social egg freezing in newspaper reports. Highly gendered messages interwoven with discourses of blame and failure were identified throughout the newspaper sample alongside moralising discourses calling for women to act responsibly towards their fertility. Emotive language and specific lexical choices were central in constructing discourses about motherhood and reproductive timing which largely excluded a consideration of the structural, relational and ideological factors which influence reproductive timing and reproductive ‘choice’. The demographic profile of interview participants was similar to that found in existing quantitative studies of social egg freezing. Participants were predominantly single, highly educated women in professional careers, with an average age of 37 at the time of undergoing egg freezing. Egg freezing was constructed by participants in relation to a particular biological project and sense of self. Motherhood was something they wanted to experience at the ‘right time’ with the ‘right partner’. The right time for motherhood was related to the feeling of ‘being ready’, which was often linked to the acquisition of certain preconditions for parenthood. The ‘right’ partner was constructed as someone who reflected certain cultural ideals often associated with ‘new fatherhood’. The absence of such a partner indicated that it was the wrong time to pursue motherhood and thus led women to pursue social egg freezing. Many participants reported that a particular issue or event had acted as a critical factor leading them to undergo egg freezing. These included the breakdown of a relationship or the diagnosis of a health or fertility related problem, thus blurring the conceptual distinction between medical and social egg freezing. Through the use of Layder’s theory of social domains and concepts of neoliberalism and biomedicalisation, the thesis argues that women’s engagement with this technology is influenced by both macro and micro sociological factors including ideologies of parenthood, an individual’s social location, relationships with intimate partners and men’s fathering intentions. When faced with the ‘risk knowledge’ of their declining ovarian reserve, the female users of this technology can be seen as enacting ‘reproductive responsibility’ commensurate with neoliberal values of responsibility, self-actualisation and self-determined action in pursuit of a particular construction of motherhood. This theorisation provides a challenge to current understandings around delayed motherhood and suggests that women’s use of social egg freezing should not be seen simply as the outcome of women’s ‘choice’, but as a process involving a complex interrelation of discourses which contextualises decision making in the reproductive realm. This research has implications for practitioners, regulators, users and potential users of this technology, as well as for researchers concerned with questions of reproductive choice, delayed motherhood and reproductive timing.

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Shanmugam, Dinesh Kumar, and dshanmugam@swin edu au. "Development of ice particle production system for ice jet process." Swinburne University of Technology. Industrial Research Institute Swinburne, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20050805.145343.

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This thesis presents a comprehensive study of the ice particle production process through experimentation and numerical methods using computational fluid dynamics (CFD) that can be used to produce ice particles with controlled temperature and hardness for use in ice jet (IJ) process for industrial applications. The analytical and numerical modeling for the heat exchanger system are developed that could predict the heat, mass and momentum exchange between the cold gas and water droplets. Further, the feasibility study of the deployment of ice particles produced from the ice jet system for possible cleaning and blasting applications are analyzed numerically. Although the use of Abrasive Water Jet (AWJ) technology in cutting, cleaning, machining and surface processing is a very successful industrial process, a considerable amount of secondary particle waste and contamination impingement by abrasive materials has been an important issue in AWJ process. Some alternate cryogenic jet methods involving vanishing abrasive materials, such as plain liquid nitrogen or carbon dioxide have been tried for these applications, but they also suffer from certain drawbacks relating to the quality, safety, process control and materials handling. The use of ice jet process involving minute ice particles has received relatively little attention in industrial applications. Some researches have concentrated on the studies of effects of Ice Jet outlet parameters of the nozzle and focus tube for machining soft and brittle materials. Most of the work in this area is qualitative and researchers have paid a cursory attention to the ice particles temperature and the efficiency of production of these particles. An extensive investigation to gain insight knowledge into the formulation of ice formation process parameters is required in arriving at a deeper understanding of the entire ice jet process for production application. Experimental investigations were focussed on the measurement of ice particle temperature, phase transitions, ice particle diameter, coalescence and hardness test. The change in ice particle diameter from the inlet conditions to the exit point of the heat exchanger wasinvestigated using the experimental results. These observations were extended to numerical analysis of temperature variations of ice particles at different planes inside the custom built heat exchanger. The numerical predictions were carried out with the aid of visualization studies and temperature measurement results from experiments. The numerical models were further analysed to find out the behaviour of ice particles in the transportation stage, the mixing chamber of the nozzle and focus tube. This was done to find out whether the methodology used in this research is feasible and if it can be used in applications such as cleaning, blasting, drilling and perhaps cutting. The results of the empirical studies show that ice particles of desired temperature and hardness could be produced successfully with the current novel design of the heat exchanger. At the optimum parameters, ice particles could be produced below -60�C, with hardness of particles comparable to gypsum (Moh�s hardness of 1.5 to 3). The visualization studies of the process assisted in observation of the phases of ice at various points along the heat exchanger. The results of numerical analysis were found to agree well with the experiments and were supported by the statistical model assessments. Numerical analyses also show the survival of ice particles at the nozzle exit even with high-pressure, high-velocity water/air mixture.

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Kenneway, Debra A. "Higher-Order Physic for Modeling Ice Streams in Ice Sheets." Fogler Library, University of Maine, 2010. http://www.library.umaine.edu/theses/pdf/KennewayDA2010.pdf.

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De, Angelis Hernán. "Palaeo-ice streams in the north-eastern Laurentide Ice Sheet /." Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm university, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7116.

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El-Fashny, Kamal. "Modeling ice loads using passive ice meter obervations in Quebec." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82865.

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Climatic loads (wind speed and ice accumulation) are the main factors that govern the planning and design of telecommunication towers and electric transmission lines. Whilst wind loads are covered comprehensively in the literature and in design standards, ice loads and rules for combination of wind speed on ice-covered-structures are still in development. The main difficulty in achieving a design that meets a target reliability level as specified in design codes is the uncertainty in the temporal and spatial variation of ice accretion. Due to the lack of sufficient direct field measurements, empirical models are usually utilized in combination with meteorological data to estimate the intensity of ice accumulation at specific locations.
A unique database of direct measurements on ice accumulation is available in Quebec. More than 20 years of observations from a network of 180 Passive Ice Meters (PIM) are available throughout the province. The objective of this study is to analyze this data set in order to improve existing regional design criteria and for better understanding of the atmospheric icing phenomena in Quebec. The research is limited to the study of glaze ice, which occurs in conjunction with freezing precipitation.
Firstly, several extreme-value statistical models are investigated to determine the best one or ones for describing the intensity of glaze ice accumulation. In order to increase the sample size, an event-based model, in which every icing event is counted as an independent event, is adopted. Twelve probability distribution functions are examined. The distributions are compared on the basis of the overall fit to the data and the sampling characteristics of the right tail of the distributions. No single distribution fits the data perfectly at all stations. However, the three-parameter distributions, and in particular, the Pearson type III, Generalized Pareto, Generalized Normal, and Generalized Extreme-Value distributions are the best on average. The commonly used Gumbel distribution is consistently outperformed by the three-parameter distributions.
Secondly, a reliability-based procedure is proposed for the analysis of the combined wind and ice loads and in particular for associated pressure on overhead transmission lines. Finally, a procedure for the spatial interpolation of design criteria is investigated. Spatial interpolations of the design ice thickness for a 50-years return period is performed using Kriging.

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Smith, Helen. "Scattering ice clouds." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/scattering-ice-clouds(949032cc-fbdd-4fde-a942-163d870a5ddd).html.

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The 2013 meeting of the Intergovernmental Panel on Climate Change concluded that the coupling of clouds to the Earth's climate is one of the biggest uncertainties faced in predicting climate change today. Cirrus clouds are of particular interest because the extensive variability in particle size, shape and complexity poses a number of challenges in the accurate modelling of optical properties. The dependence of the single-scattering properties on particle shape demand accurate representation of the crystal geometries in scattering models, geometries which can vary from simple hexagonal prisms to complex multi-branched aggregates. This work, presented as a series of papers, uses laboratory studies to investigate the single scattering properties of ice crystals. Of particular focus here are columns with internal cavities. The first paper investigates the phase function, P11 and asymmetry parameter, g of varying crystal habits, whilst the second paper focuses on polarised scattering. One of the main findings is the difference in internal structure between hollow columns grown at warmer temperatures (-7 degrees C) and those grown at colder temperatures (-30 degrees C). Measurements were used to create new particle geometries for use in scattering models. The third paper makes use of findings from papers 1 & 2 to create an optical parametrization for cirrus, utilizing the new particle geometry.

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Sargent, Aitbala. "Modeling Ice Streams." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/SargentA2009.pdf.

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Kietzig, Anne-Marie. "Microscopic ice friction." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23322.

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Microscopic ice friction was studied systematically across all to ice friction relevant friction regimes using several metallic interfaces. A rheometer with a newly designed fixture for friction measurements was used in these studies. The investigations focus on the influence of material properties, such as surface wettability, roughness, surface structure, surface nanopatterning, and thermal conductivity. Using a femtosecond laser process certain dual scale roughness structures were created to mimic the lotus leaf on the surface of inherently hydrophilic metal alloys. After laser irradiation the samples show initially superhydrophilic behavior with complete wetting of the structured surface. However, over time these surfaces become hydrophobic to superhydrophobic. The change in wetting behavior correlates with the amount of carbon found on the structured surface. The explanation for the time dependency of the surface wettability lies in the combined effect of surface morphology and surface chemistry. With regard to ice friction this controlled lotus-like roughness significantly increases the coefficient of friction at low sliding speeds and temperatures well below the ice melting point. However, at temperatures close to the melting point and relatively higher speeds, roughness and hydrophobicity significantly decrease ice friction. This decrease in friction is mainly due to the suppression of capillary bridges. The influence of surface structure on ice friction was also investigated isolated from the effect of surface roughness. It is shown that grooves oriented in the sliding direction also significantly decrease friction in the low velocity range compared to scratches and grooves randomly distributed over a surface. The isolated effect of thermal conductivity on ice friction is investigated by thermally insulating the slider and the friction fixture with fiberglass. A decrease of the friction coefficient in the boundary friction regime and an earlier onset of the mixed friction regime in terms of sliding velocity are reported. Furthermore, the dependence of the ice friction coefficient on sliding velocity is compared for different sliding materials. It was concluded that the influence of thermal conductivity decreases with increasing sliding velocity.

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Gray, J. M. N. T. "Sea ice dynamics." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240183.

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Smith, Benjamin E. "Characterization of the small scale ice sheet topography of Antarctica and Greenland /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6812.

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Ueland, Sindre, and Sverre Wendt Slettebø. "Control Strategies for Maneuvering in Ice Ridge and Multi Ice Regimes." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11625.

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Operations in an arctic environment are dependent on accurate, safe and reliable Dynamic Positioning (DP) systems. Increased activities in arctic environments have lead to a demand for knowledge of different ice regimes and their affection on offshore structures and vessels. The purpose of this master thesis is to create a simulation tool for interaction between an ice ridge and a marine vessel and to propose a special purpose DP-system for use in arctic environment. The thesis has been divided into two parts. First an ice ridge model was created in order to realistically simulate an interaction between a marine vessel and an ice ridge. Secondly several DP-tactics for station keeping in arctic environment was proposed and tested against the ice ridge model. Different theories and calculation methods regarding resistance from an ice ridges have been discussed. An ice ridge model was proposed and discussed, and a parameter analysis of the ice ridge model was performed. Ridge size, ridge velocity and vessel dimensions were varied to investigate the total resistance. Simulations showed that that the ice resistance varied with the different parameters. It was shown that increased vessel width will gave an increased bow resistance, while the mid body resistance remained unchanged. Comparison with available literature proposes that the keel and sail contribution of the total resistance is small. Drawbacks with the ice ridge model have been discussed and further work proposed. An open-water DP-system was created and supplied with different ice breaking features to ensure station-keeping in a ridge-vessel collision. Five different features was described and discussed. Simulations of station keeping have been performed using the ice ridge model. Simulations of the open-water DP-system were used as a reference and for comparison with the special purpose DP-system. The different ice breaking features were then discussed and compared. The simulation study indicated that the open-water control system may not offer optimal performance when exposed to ice ridge forces and that a special purpose controller should be considered. For a marine vessel subjected to an incoming ice ridge, simulation results showed improved station keeping abilities with use of a special purpose controller. However, the special purpose controller proposed in this master thesis assumes detailed knowledge about the incoming ice ridge. For a real world system such detailed knowledge about an incoming ice ridge would require an advanced sensor system, something that have not been considered in this thesis but proposed for further work.

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Lundberg, Anders, and Daniel Sjörs. "Off-ice vs. on-ice : Hopptesters samband med skridskoåkning i ishockey." Thesis, Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:gih:diva-2543.

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Aim The purpose of this study was to investigate the relationship between off-ice horizontal jump tests and on-ice skating among students at hockey high schools. Questions: What is the association between the performance on horizontal jumps and skating 10 meters standing start among students in Swedish ice hockey high schools? What is the association between the performance on horizontal jumps and skating 10 meters flying start among students in Swedish ice hockey high schools? Method Students at three ice hockey high schools in the Stockholm area participated in the study. Two schools were national approved sports educations and one at lower level. All 50 students (41 at national approved sports educations and 9 lower level) that were included in the study were men and went year one and two in gymnasium. Horizontal jump test, standing long jump, standing long jump on one leg (right and left) and standing five step jump was carried out off-ice. A 40-meter sprint skating was on-ice, where times for standing 0-10 meters and flying 10 meters were used in further analysis. The degree of linear relationship between the variables on-ice skating and off-ice tests were measured using Pearson's correlation coefficient. Results Standing long jump on one leg (right and left) was highly correlated to both skating 0-10 meters standing start (r = -0.599) and skating 10 meters flying start (r = -0.635) among all skaters in this study. The respective associations with standing five step jump were r = -0.467 and r = -0.582 whereas for standing long jump they were r = -0.459 and r = -0.599. Conclusions Standing long jump on one leg (right and left) correlates best with skating, both the 0-10 meters standing start, and the 10 meters flying start. Generally, there was a higher correlation between the three jump tests and skating 10 meters flying start than 0-10 meters standing start. Based on this study's results, we consider that the standing long jump on one leg (right and left) should be included in the test battery that national approved sports educations colleges conduct.
Syfte och frågeställningar Syftet med denna studie var att undersöka samband mellan horisontella hopptester off-ice och on-ice skridskoåkning hos ishockeyspelare på svenska ishockeygymnasier. Frågeställningar: Hur ser sambandet ut mellan prestationer i horisontella hopp och skridskoåkning 10 meter stående start bland elever på svenska ishockeygymnasier? Hur ser sambandet ut mellan prestationer i horisontella hopp och skridskoåkning 10 meter flygande start bland elever på svenska ishockeygymnasier? Metod Elever på tre ishockeygymnasier i Stockholmsområdet deltog i studien. Två skolor var Nationellt godkänd idrottsutbildning (NIU) och ett på lokal nivå. Alla 50 elever (41 på NIU och 9 på lokal nivå) som ingick i studien var män och gick år ett och två på gymnasiet. Horisontella hopptester, så som stående längdhopp, stående längdhopp på ett ben samt stående femsteg genomfördes off-ice. Ett sprinttest 40 meter skridskoåkning genomfördes on-ice, där tider för stående 0-10 meter samt flygande 10 meter användes i vidare analys. Graden av linjärt samband mellan variablerna on-ice skridskoåkning och off-ice testerna mättes med hjälp av Pearsons korrelationskoefficient. Resultat Stående längdhopp på ett ben (höger och vänster) hade en hög korrelation både mot skridskoåkning 0-10 meter stående start (r = -0,599) och skridskoåkning 10 meter flygande start (r = -0,635) bland alla utespelare i denna studie. Sambanden med stående femsteg var r = -0,467 respektive r = -0,582, medan sambanden med stående längdhopp var r = -0,459 respektive r = -0,599. Slutsats Stående längdhopp på ett ben (höger och vänster) korrelerar bäst med skridskoåkning, både mot 0-10 meter stående start och mot 10 meter flygande start. Generellt finns ett högre samband mellan de tre hopptesterna och skridskoåkning 10 meter flygande start än 0-10 meter stående start. Utifrån denna studies resultat anser vi att stående längdhopp på ett ben (höger och vänster) bör införas i det testbatteri som NIU-gymnasierna genomför.

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Edman, Sebastian, and Tobias Esping. "Squats as a predictor of on-ice performance in ice hockey." Thesis, Högskolan i Halmstad, Biomekanik och biomedicin, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-23284.

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Introduction: The National Hockey League Entry Draft Combine (NHLED Combine) is considered one of the toughest physical fitness tests an ice hockey player has to go through. The NHLED Combine consists of several fitness tests evaluating the athlete’s aerobic- and anaerobic capacity; lower body power, upper body strength and power, flexibility and anthropometrics; no lower body strength test are employed. Squats are the only exercise used by all National Hockey League (NHL) strength and conditioning coaches yet it is not included in the NHLED Combine. Purpose: The purpose of this study was to determine which off-ice test correlates best with on-ice performance measured as forward skating speed. We hypothesised that squat one repetition maximum (squat 1RM) would be a better or equal predictor of on-ice performance compared to the current NHLED Combine tests standing long jump (SLJ) and Wingate anaerobic test (WAnT). Method: Eleven male subjects, aged 17.8 ± 0.8 years, performed an on-ice sprint followed by the off-ice tests SLJ, WAnT and squat 1RM. Results: A correlation was found between sprint time on-ice and SLJ (r= -0,727, p= 0.006), Wingate anaerobic test mean power/ body weight (WAnT MP/BW) (r= -0,607, p= 0,024), squat 1RM (r= -0,600, p= 0.026) and squat 1 repetition maximum/body weight (squat 1RM/BW) (r= -0,609, p= 0.023). Conclusion: The results indicate that squat 1RM and squat 1RM/BW are equally good predictors of hockey performance as SLJ and WAnT MP/BW.
knäböj, hockey, is, nhl, skridskoåkning, skridskoskär, sprint, horisontalhopp, wingate, styrka, kraftutveckling, fystest

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Papa, Brian D. "Large-scale ice discharge events in a pure ice sheet model." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81421.

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Sediment cores in the North Atlantic show evidence of periodic large-scale ice discharge events between 60 kyr and 10 kyr before present. These so-called Heinrich Events (HEs) occurred with a typical period between 5 kyr and 10 kyr. During each HE, a significant amount of ice was discharged from the Laurentide ice sheet into the North Atlantic. This input of freshwater through the melting of icebergs is thought to have strongly reduced the strength of the Atlantic thermohaline circulation.
One theory for HEs is that they are due to an internal oscillation of the ice sheet under constant forcing. This implies that past multi-millennial scale climate variations in the North Atlantic region may have been driven by variations in the Laurentide ice sheet and were not externally forced by climate change or sea level variations. A second theory for HEs requires some variable external forcing on an unstable ice sheet to produce a discharge event.
Using the 3-D ice sheet model of Marshall and Clarke (1997a,b), which includes ice sheet dynamics and thermodynamics, the possibility of internal oscillations within an ice sheet is verified and an analysis of the mechanisms associated with these oscillations is performed. The bed topography and strain heating are found to be critical for the formation and development of fast moving ice streams, which lead to large iceberg calving. In addition, the calving parameterization is found to be an important factor in the ability of the model to periodically discharge large amounts of ice.

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Davies, Edward. "Neutron diffraction studies of amorphous ice and amorphous ice co-deposits." Thesis, University of Kent, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305366.

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Womack, Ashleigh Catherine Stevenson. "Atmospheric drivers of ice drift in the Antarctic marginal ice zone." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33982.

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Sea-ice drift in the Antarctic marginal ice zone (MIZ) was investigated using an array of five drifting ice buoys, deployed during the winter sea-ice expansion, in July 2017. An initial 15- day analysis of pancake ice drift is presented, using the cluster of buoys, which shows: (1) exceptionally fast ice drift speeds and increased meandering of the buoys during cyclone activity; (2) high correlation of drift velocities with the surface wind velocities, even at 100% remotely sensed ice concentration, indicating free drift conditions where ice drift is primarily governed by wind; and (3) the presence of a clear energy peak (»13.5 hour period), which is suggested to be excited by the passage of cyclones through the transfer of momentum from wind. Additionally, one of the buoys (buoy U1) drifted for approximately four months from the South Atlantic sector to the Indian Ocean sector of the Southern Ocean. The analysis of this buoy revealed that it remained within the MIZ even during the winter ice expansion, as the mixed pancake-frazil field was maintained. This allowed for a continued assumption of free drift conditions for buoy U1's full drift, where it continued to respond linearly to the momentum transfer from surface winds. The analysis of buoy U1 also indicated a strong inertial signature at a period of 13.47 hours however, the wavelet analysis indicated majority of the power remained within the lower frequencies. This strong influence at the lower (multiday) frequencies has therefore been identified as the primary effect of atmospheric forcing. When these lower frequencies were filtered out using the Butterworth high-pass filter it allowed the inertial oscillations to become more significant within the wavelet power spectrum, where it can be seen that these inertial oscillations were often triggered by the passage of cyclones. The initiation of inertial oscillations of sea ice has therefore been identified as the secondary effect of atmospheric forcing, which dominates ice drift at sub-daily timescales and results in the deviation of ice drift from a straight-line path. This comprehensive analysis suggests that the general concentration-based definition of the MIZ is not enough to describe the sea-ice cover, and that the MIZ, where ice is in free drift and under the influence of cyclone induced inertial motion, and presumably waves, can extend up to »200 km.

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Stewart, Craig Lincoln. "Ice-ocean interactions beneath the north-western Ross Ice Shelf, Antarctica." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274361.

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Basal melting of ice shelves is causing accelerating mass loss from the Antarctic Ice Sheet, yet the oceanographic processes which drive this are rarely observed. This thesis uses new observations from phase sensitive radar and moored oceanographic instruments to describe the processes which drive rapid basal melting of the north-western Ross Ice Shelf. Oceanographic conditions at the mooring site are strongly influenced by the neighbouring Ross Sea Polynya. High Salinity Shelf Water fills the lower water column continuously, but during summer a southward flow ventilates the cavity bringing Antarctic Surface Water (AASW) to the site. Tides account for half of the flow speed variance, and low frequency variability is influenced by local winds, and eddies associated with sea ice production in the polynya. Four years of basal melt rate observations show a mean melt rate of 1.8 m y$^{-1}$ at the mooring site and a strong seasonal cycle driven principally by water temperature variations. Radar observations show that melt rates vary rapidly and continuously in response to flow speed variability, and rapid melting occurs only when flow speeds are high. Radar observations of melt rates from 78 sites on the Ross and McMurdo ice shelves show an area-averaged annual-mean basal melt rate of 1.35 m y$^{-1}$, implying a net basal mass loss of 9.6 Gt y$^{-1}$ from the region. Melt rates are highest near the ice front where annual-mean and short-term summer rates reached 7.7 m y$^{-1}$ and 53 m y$^{-1}$, respectively. The seasonal and spatial variations in melt rate are consistent with melting driven by the summer inflow of AASW. Observations of boundary layer water temperature, flow speed and melt rates indicate that melt rates scale linearly with current speed, but sub-linearly with temperature in the outer boundary layer, possibly due to the stabilising effects of melt water input. Existing melt rate parameterisations which account for flow speed can be tuned to match the observations when thermal driving is low, but overestimate melt rates at higher temperatures, implying the need for further refinements to the models.

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Zhang, Zhanhai. "On modelling ice dynamics of semi-enclosed seasonally ice-covered seas." Helsinki : University of Helsinki, 2000. http://ethesis.helsinki.fi/julkaisut/mat/geofy/vk/zhang/.

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Dierckx, Marie. "Marine ice rheology from deformation experiments of ice shelf samples using a pneumatic compression device: implications for ice shelf stability." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209505.

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Antarctic ice shelves control the ice flux from the continent to the ocean. As such, they play a major role in the stability of the ice sheet and its potential contribution to sea level rise, especially in the context of global change. Below some of these ice shelves, marine ice can be found which is a product of the Deep Thermohaline Circulation. Due to its specific genetic process, marine ice has intrinsic physical (grain size, ice fabric, bubble content, ) and chemical (impurities, water stable isotopes) properties, that differ from those of 'meteoric ice' formed on the continent through snow metamorphism or 'sea ice' resulting from sea water freezing at the ocean-atmosphere surface. Until now however, the effect of these specific properties on marine ice rheology is still very poorly understood.

The principal objective being to include realistic mechanical parameters for marine ice in ice shelf flow models, uniaxial compression experiments have been performed on various types of marine ice samples. Technical developments are an important component of this thesis has they were necessary to equip the laboratory with the appropriate tools (pneumatic rig, automatic ice fabric data handling).

Results from experimental compression on isotropic marine ice show that it represents the higher boundary for meteoric ice viscosity throughout the whole temperature range, thereby validating Cuffey and Paterson's relationship with an enhancement factor equals to 1.

Marine ice is however often quite anisotropic, showing elongated crystals and wide single maximum fabric, that should impact its mechanical properties. Experiments on pre-oriented marine ice samples have therefore been carried out combining the study of epsilon_{oct} vs. tau_{oct} with a thorough analysis of microstructural data 'before' and 'after' the experiment.

Depending on the orientation of the sample in the applied stress field and on the intensity of the latter, anisotropic marine ice can be harder or softer than its isotropic counterpart, with n=4 often observed in Glen's flow law. Associating the experimental geometrical settings to potential natural equivalent, results suggest that anisotropic marine ice would strengthen ice shelf flow in most areas (for a same given temperature), apart from suturing areas between individual ice streams as they merge to form the ice shelf, where it could become weaker than meteoric ice in certain circumstances.

Finally, preliminary sensitivity studies, using a simple ice shelf model with our experimental parameters of Glen's flow law have allowed us to discuss the potential impact of rift location, rift size and thermal regime in the ice shelf behavior.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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Liferov, Pavel. "First-year ice ridge scour and some aspects of ice rubble behaviour." Doctoral thesis, Norwegian University of Science and Technology, Department of Civil and Transport Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1712.

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Johnston, Michelle E. "Influence of ice microstructure on the microwave scattering properties of sea ice." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0013/NQ36280.pdf.

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Bleidorn, John Charles. "Momentum exchange near ice keels in the under ice ocean boundary layer." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://bosun.nps.edu/uhtbin/hyperion-image.exe/08Mar%5FBleidorn%5FJohn.pdf.

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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, March 2008.
Thesis Advisor(s): Stanton, Timothy. "March 2008." Description based on title screen as viewed on April 25, 2008. Includes bibliographical references (p. 35). Also available in print.

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Brayne, Stephen. "A comparison of on-ice and laboratory tests of ice hockey fitness /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63132.

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Schannwell, Clemens. "Modelling ice dynamic sea-level rise from the Antarctic Peninsula Ice Sheet." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7775/.

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The Antarctic Peninsula (AP) has been one of the most rapidly warming regions on this planet. This warming has been accompanied by major glaciological changes such as tidewater glacier retreat, ice-shelf retreat and collapse alongside acceleration of outlet glaciers in response to ice-shelf removal. As faster owing glaciers deliver more ice from the ice sheet's interior to the margins, the AP has been identified as an important contributor to global sea-level rise (SLR). However, comprehensible SLR projections of the AP induced by ice dynamics over the next three centuries are still lacking. In this thesis, numerical ice-sheet models are utilised to present scenario-based ice dynamic SLR projections for the AP.

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Palais, Julie Michelle. "Tephra layers and ice chemistry in the Byrd-Station ice core, Antarctica." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299252349.

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Guo, Wenkai. "The relationship between sea ice retreat and Greenland ice sheet surface-melt." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397692613.

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Smith, Alexandra Michaele. "Injury Profiles and Off-ice Jumping Analysis of Female Synchronized Ice Skaters." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1529341696268529.

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Kyrke-Smith, Teresa Marie. "Ice-stream dynamics : the coupled flow of ice sheets and subglacial meltwater." Thesis, University of Oxford, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629515.

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Ice sheets are among the key controls on global climate and sea level. A detailed understanding of their dynamics is crucial to make accurate predictions of their future mass balance. Ice streams are the dominant negative component in this balance, accounting for up to 90% of the Antarctic ice flux into ice shelves and ultimately into the sea. Despite their importance, our understanding of ice-stream dynamics is far from complete. A range of observations associate ice streams with meltwater. Meltwater lubricates the ice at its bed, allowing it to slide with less internal deformation. It is believed that ice streams may appear due to a localisation feedback between ice flow, basal melting and water pressure in the underlying sediments. This thesis aims to address the instability of ice-stream formation by considering potential feedbacks between the basal boundary and ice flow. Chapter 2 considers ice-flow models, formulating a model that is capable of capturing the leading-order dynamics of both a slow-moving ice sheet and rapidly flowing ice streams. Chapter 3 investigates the consequences of applying different phenomenological sliding laws as the basal boundary condition in this ice-flow model. Chapter 4 presents a model of subglacial water flow below ice sheets, and particularly below ice streams. This provides a more physical representation of processes occurring at the bed. Chapter 5 then investigates the coupled behaviour of the water with the sediment, and Chapter 6 the coupled behaviour of the water with the ice flow. Under some conditions this coupled system gives rise to ice streams due to instability of the internal dynamics.

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Ashmore, David W. "The basal environment of Antarctic ice streams from airborne ice-penetrating radar." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=226061.

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The presence and configuration of subglacial water and sediment maintain the fast flow of arterial ice streams in Antarctica and airborne ice-penetrating radar data represent a potential resource of information about the ice-bed interface. In this thesis an original contribution to the exploration of Antarctic subglacial environments is made through the analysis of airborne surveys from Evans, Institute and Möller Ice Streams, West Antarctica. The primary approach employed is the derivation of bed-returned power (BRP), a proxy for ice-bed reflectivity, which is strongly influenced by the presence of liquid water. Estimating radar englacial attenuation (EA) accurately is a critical part of BRP analysis and a modelled approach is primarily used. BRP is derived across Evans Ice Stream and shows large-scale patterns relating to hypothesised hydrological and geological contrasts at the ice-bed. These results are developed to investigate the influence of: (1) adopted EA correction; (2) the influence of assigned ice dielectric properties in modelled EA; (3) subglacial roughness and (4) the spatial scale over which BRP is derived. Some areas of high basal drag can be detected with BRP analysis, indicating that variations in subglacial hydrology are responsible for their existence. The widely-used empirical method of estimating EA by relating ice thickness to uncorrected BRP is shown to be unreliable where ice properties change along a transect. Monte Carlo error analysis of modelled EA shows that poorly constrained ice dielectric properties also result in significant BRP uncertainty. BRP beneath Institute and Möller Ice Streams is derived on catchment- and local-scales over hypothesised subglacial features. Bungenstock Ice Rise is marked with a clear BRP signal but the locations of "active" lakes, as delineated by satellite altimetry, do not. The sensitivity of idealised flow paths to surface change and grid size are investigated. Potential future research directions regarding BRP analysis are discussed.

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Munnerlyn, Stacey Clarke. "Sweet prospects ice and organic ice cream in the Sierra Nevada foothills /." abstract only (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1453592.

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Scoto, Federico <1991&gt. "Halogens in ice core as potential proxies for past sea ice reconstructions." Doctoral thesis, Università Ca' Foscari Venezia, 2019. http://hdl.handle.net/10579/17845.

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Da circa cinquanta anni, il ghiaccio marino in Artico sta diminuendo, sia in estensione che in volume, ad un tasso di gran lunga più veloce rispetto a quanto previsto dai modelli numerici. Sebbene a partire dai primi anni ’70 (ovvero la cosiddetta “era satellitare”), siano state acquisite numerosissime informazioni sul suo stato, vi è ancora una mancanza di conoscenza circa la sua evoluzione prima dell’avvento delle misurazioni strumentali. Per colmare questa lacuna, vengono comunemente utilizzati paleo-registri come sedimenti marini e carote di ghiaccio. In particolare, alcuni studi hanno identificato il bromo contenuto all’interno di carote di ghiaccio come un potenziale indicatore di condizioni di ghiaccio di neoformazione (o di 1° anno). Durante la primavera polare, infatti, a causa di reazioni fotolitiche che avvengono in prossimità della superficie del ghiaccio marino stagionale, vi è un efficiente riciclo di bromo inorganico che ne determina un aumento delle sue concentrazioni in fase gassosa rispetto a quella misurata al di sopra della superficie dell'oceano, del ghiaccio marino pluriennale o del suolo artico. Questo processo, noto come "esplosione del bromo", viene rilevato anche dai satelliti oltre che da misure in loco, iniziando i primi di marzo protraendosi fino a fine maggio. Dopo l'emissione, il plume arricchito in bromo viene preso in carico dalle circolazioni cicloniche presenti nella bassa troposfera polare fino a quando, raggiunta la terraferma, precipita sotto forma di neve che sarà, anch’essa, arricchita in bromo rispetto al rapporto Br/Na dell'acqua di mare. Utilizzando l’arricchimento di bromo proveniente da diverse carote di ghiaccio artiche, questa tesi è stata ideata seguendo una duplice prospettiva. Da un lato, mira a validare e calibrare il tracciante proposto con immagini satellitari del ghiaccio marino artico per il periodo 1984-2016. Dall’altro, una volta validato il tracciante, si vuole applicare l’informazione rinvenuta ad un caso di studio paleoclimatico che si pone come obiettivo quello di valutare la risposta del ghiaccio marino alle brusche instabilità climatiche dell'ultimo periodo glaciale (gli eventi D-O).

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Santanam, Suresh. "A trend study of atmospheric methane : 1965-81 GC and polar icecore measurements /." Full text open access at:, 1985. http://content.ohsu.edu/u?/etd,168.

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Pevar, Sara Lynn. "The Last Ice Age." The University of Montana, 2010. http://etd.lib.umt.edu/theses/available/etd-06182010-114322/.

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Suares, Ian Greg. "Ice particle trajectory simulation." Thesis, Wichita State University, 2005. http://hdl.handle.net/10057/1610.

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Large ice particles shed from an airframe can cause damage to downstream aerodynamic surfaces and aft mounted engines. A simulation tool was developed to compute the trajectories of shed ice particles and determine the probability of these particles passing through a particular downstream location. The flowfield into which the ice particles shed was determined using CFD. The aerodynamic forces and moments acting on the ice particles were obtained from published literature and experimental data. Three, four and six degree of freedom trajectory simulation models were developed to compute the trajectories of shed ice particles. Monte Carlo simulations were performed by varying the aerodynamic and geometric properties of the ice particles to obtain a probability map depicting the regions where the ice particles were most likely to strike.
Includes bibliographical references (p.117-120)

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Knausgård, Kjetil. "Superhydrophobic Anti-Ice Nanocoatings." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19403.

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Atmospheric icing from supercooled droplets in the atmosphere can have catastrophic consequences for a number of man-made structures in regions with cold climate and at high altitude, resulting in accidents with both socioeconomic losses and loss of human lives. To mitigate the icing problem, active de-icing involving chemical, thermal and mechanical techniques have been developed to remove ice that has already accumulated. These techniques are sub-optimal, however, as they are plagued with problems such as high energy consumption, hazard to the environment, high economic costs, and need for frequent reapplication. This thesis takes a look at an entirely different approach, namely utilizing superhydrophobic surfaces to reduce or eliminate the accumulation and adhesion of ice from the outset. Much of the research in the field of superhydrophobicity has involved surfaces with open-cell structures, e.g. pillar-like surfaces and surfaces with bumps and valleys. It has been reported that surfaces with closed cells have a comparative advantage in that they are better at retaining their hydrophobic properties under pressure. This thesis investigates the wetting properties (which are often closely tied to icephobic properties) of closed-cell structures further, using LAMMPS simulations. The simulations show that wetting on these surfaces satisfies the well-known theories of Wenzel and Cassie-Baxter. However, on the small scale on which the simulations were carried out, the effect of tuning the roughness scale is not as predicted by theory. Furthermore, no comparative advantage against open-cell structures could be demonstrated for the closed-cell surfaces. A physical experiment was also carried out, in which the influence of water condensation on the dynamic behavior of water droplets on a nearly-superhydrophobic black silicon surface was tested. The results confirm a well-known problem: Condensation severely deteriorates the water repellency of hydrophobic surfaces. The literature review and experiments in this thesis shows that superhydrophobic surfaces have a great potential for use in anti-icing applications, demonstrating delayed freezing, reduced ice accumulation, and reduced ice adhesion. Nevertheless, major problems are yet to be solved, including deterioration of icephobicity due to mechanical damage, and reduced icephobicity in humid conditions.

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Nzokou, Tanekou François. "Ice rupture hydrodynamic modeling." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/26683/26683.pdf.

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Dissertations / Theses on the topic 'Ice'

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