Large Ice Block Research Articles

A Reconsideration of the Word, Image, and Event of Frozenism: A Correlation Study for the Meaning of the Ice and Frozen Image

This Frozenism project was started to explore a new visual language, which evolved into the big idea of the meaning of the properties of frozen through ice. The concept of Frozenism has developed into ‘a conceptual approach that can be interpreted in various ways’ by combining words with various meanings and has been expanded to combine with various images and events. After creating a frozen typeface with different ice shapes, a new visual language was developed by combining various ice shapes, words, and images. Many social issues, words, images, and events related to ‘environment and war’, which are closely related to ‘life and death’, were selected and combined with ice to deliver various meanings and messages to viewers. In Frozenism, the ice expands, shatters, and creates new meanings for words, images, and events. Paper cutout letters, images, and objects are frozen within small and large ice blocks. The image of ice reflects three different aspects of the word: protection (to keep, to preserve), stillness (to lock, to hold), and death (to stop). The ice and the act of freezing externalize the concept of preserving a fragment, holding an event, and stopping a moment in time. When a word, image or event is isolated in ice, it requires a different approach from the viewer: a reconsideration of the word, image, and event. As a result, the poetic visuals of Frozenism struggle to extend, create, and even stop time. The conceptual words, images, and events in ice encourage viewers to minutely analyze the world they live in and the effects they have on the surrounding environment and society.

Experimental Thermal Study of Ice Slurry Production System Equipped With Direct Contact Heat Exchanger and Spiral Nozzle

Abstract For the direct contact ice slurry production system, the obstacles of ice blockage in the nozzle, enormous refrigerant charge, and refrigerant-water separation restrict its commercial application. In this paper, a novel direct contact ice slurry production system is proposed to overcome these obstacles. In this novel system, the horizontal PVC pipe with the spiral nozzle is designed as a direct contact ice slurry generator to avoid ice blockage in the nozzle. The two-phase RC318 is utilized as the system refrigerant. In order to investigate the ice production performance of this novel system, the effects of compressor rotational speed, internal water flowrate, and initial system pressure on ice production performance are experimentally studied, and a lump model is established. The results show that the ice production performance is mainly affected by the compressor rotational speed, but scarcely affected by the internal water flowrate. However, large ice blocks are formed at small internal water flowrate. Besides, the lump model is considered to be able to predict the water temperature. Furthermore, the sinking of the liquid refrigerant exits under the higher initial system pressure, but it can be avoided by reducing the initial system pressure.

A particle based simulation model for glacier dynamics

Abstract. A particle-based computer simulation model was developed for investigating the dynamics of glaciers. In the model, large ice bodies are made of discrete elastic particles which are bound together by massless elastic beams. These beams can break, which induces brittle behaviour. At loads below fracture, beams may also break and reform with small probabilities to incorporate slowly deforming viscous behaviour in the model. This model has the advantage that it can simulate important physical processes such as ice calving and fracturing in a more realistic way than traditional continuum models. For benchmarking purposes the deformation of an ice block on a slip-free surface was compared to that of a similar block simulated with a Finite Element full-Stokes continuum model. Two simulations were performed: (1) calving of an ice block partially supported in water, similar to a grounded marine glacier terminus, and (2) fracturing of an ice block on an inclined plane of varying basal friction, which could represent transition to fast flow or surging. Despite several approximations, including restriction to two-dimensions and simplified water-ice interaction, the model was able to reproduce the size distributions of the debris observed in calving, which may be approximated by universal scaling laws. On a moderate slope, a large ice block was stable and quiescent as long as there was enough of friction against the substrate. For a critical length of frictional contact, global sliding began, and the model block disintegrated in a manner suggestive of a surging glacier. In this case the fragment size distribution produced was typical of a grinding process.

Surface wave generation due to glacier calving

Coastal glaciers reach the ocean in a spectacular process called ‘calving’. Immediately after calving, the impulsive surface waves are generated, sometimes of large height. These waves are particularly dangerous for vessels sailing close to the glacier fronts. The paper presents a theoretical model of surface wave generation due to glacier calving. To explain the wave generation process, four case studies of ice blocks falling into water are discussed: a cylindrical ice block of small thickness impacting on water, an ice column sliding into water without impact, a large ice block falling on to water with a pressure impulse, and an ice column becoming detached from the glacier wall and falling on to the sea surface. These case studies encompass simplified, selected modes of the glacier calving, which can be treated in a theoretical way. Example calculations illustrate the predicted time series of surface elevations for each mode of glacier calving.

Sedimentary architecture of large-scale, jökulhlaup-generated, ice-block obstacle marks: Examples from Skeiðarársandur, SE Iceland

During glacial outburst floods (jokulhlaups) large ice-blocks are often released from the glacier margin. Ice-blocks ground at points of flow deceleration, generating distinctive patterns of scour and deposition scaled to the obstacle size. The large-scale ice-block obstacle marks produced within the proglacial zone are diagnostic of jokulhlaups. We use ground-penetrating radar (GPR) to investigate the sedimentary architecture of ice-block obstacle marks generated by the November 1996 jokulhlaup at Skeiðararjokull, Iceland. The GPR data reveal a varied sedimentary architecture, interpreted to suggest that ice-block obstacle mark sedimentology is controlled by flow conditions, sediment supply, and whether ice blocks are deposited in isolation or as a cluster. Following ice-block grounding, deflection of flow down and away from the obstacle develops horseshoe vortices that maintain a non-depositional hollow around the obstacle, whilst continued outwash deposition away from the obstacle raises the level of the surrounding sandur. Where ice-blocks ground early during the jokulhlaup, hollows are infilled with foreset beds at the up-flow end and backset beds (antidune) distally. However, where ice-blocks ground on the waning stage when sediment flux is reduced, antidunes are not preserved and the hollow is infilled with low-angle foreset beds. In both cases the lee-side shadow ridge is composed of pseudo-anticlinal beds proximal to the obstacle (where shed vortices are strong) and plane beds distally (where flows converge and the shed vortices weaken). Where flow parallel ice-block clusters develop, the grounding of smaller ice-blocks in the lee of the initial obstacle results in only limited shadow ridge aggradation. These data provide improved insight into the controls on ice-block obstacle mark sedimentary architecture and allow identification of high-magnitude jokulhlaups in the sedimentary record.

Late Pleistocene stratigraphy of Upper Cape Cod and Nantucket Sound, Massachusetts

Soon after the Laurentide ice sheet reached its maximum southern extent at Martha's Vineyard and Nantucket islands 21,000–20,000 yr ago, a system of subglacial tunnel valleys, extending from southern Cape Cod (the Upper Cape) to the ice margin, were eroded into the fine-grained sediments resting on basement. We infer that these fine-grained sediments may represent Illinoian proglacial lake deposits that were fluvially eroded prior to late Wisconsin. During the Wisconsin glacial retreat, a proglacial lake formed in Nantucket Sound and sediments ranging from clay to fine sand were deposited. Compaction of the clays in the sound suggests that these sediments may have experienced glaciotectonic deformation resulting from minor advances during the overall glacial retreat. When the ice margin reached the south shore of the Upper Cape 19,000 yr ago it temporarily halted and a poorly sorted mixture of gravel, sand, and mud (ice-contact deposits) was emplaced along the jagged ice front on the north shore of the proglacial lake in Nantucket Sound. As the ice re-initiated its northward retreat another lake was formed in the Upper Cape. This lake may have separated from the one in Nantucket Sound by the ice-contact facies ridge. As the lake in the Upper Cape grew northward, keeping pace with the retreating ice front, very fine sands, silty sands and sandy silts were emplaced over the Illinoian lacustrine clays. When the ice front reached a sharp change in basement slope in central Upper Cape the ice fragmented and large ice blocks were left behind. A mixed unit of sands interbedded with silt and clay was deposited in front of the ice and between the ice blocks. The mixed unit prograded southward into the proglacial lake as a series of overlapping deltas with the distal end of the basin being a site of finer sediment accumulation. With continued northward retreat of the ice front, another proglacial lake formed north of the mixed unit that was dammed to the south by the stranded ice blocks and the mixed unit. Eventually the water level in this basin rose sufficiently that one lake extended from the glacial front to the ice-contact facies ridge along the south shore of the Upper Cape. Soon thereafter, the ridge along the south shore of the Upper Cape was breached and the lake in the Upper Cape joined the glacial lake in Nantucket Sound. Linkage of the lake in the Upper Cape with the Nantucket Sound lake was soon followed by the collapse of the southern dam of the lake in the sound. This event resulted in erosion of lake sediments in the Upper Cape and Nantucket Sound, with erosion in the Upper Cape being so pronounced as to exhume the Illinoian lake sediments. A braided fluvial system deposited outwash sands and gravels on the exposed erosional surface. Construction of these outwash plains stopped about 17,000 yr ago and they underwent fluvial erosion. Lows in this fluvial terrain became sites of local lacustrine deposition. Soon thereafter, outwash deposition was re-initiated, burying the previously exposed sediments. After the outwash plains were constructed, groundwater seeps, associated with a proglacial lake in Cape Cod Bay to the north, eroded a series of parallel linear valleys on the outwash plains. The last Wisconsin event in the Upper Cape was the formation of a kettle lake system when the buried ice blocks melted. The lakes became sites of deltaic deposition during a moister period 11,000–8000 yr ago when the water level in these lakes was higher than now. The present configuration of Nantucket Sound and the coastal zone is the result of deposition and erosion during and after the Holocene transgression.

A description of crevasse formation using continuum damage mechanics

AbstractContinuum damage mechanics describes the progressive deterioration of material subjected to loading. Jointly used with a level-set method, it proves to be a promising approach to computing the interface motion of a damaged material. For polycrystalline ice, a local isotropic damage evolution law (generalized Kachanow’s law) applied to Glen’s flow law allows the description of tertiary creep and facilitates the modeling of crevasse opening using a failure criterion based on damage accumulation. The use of a level-set method permits the description, in a continuum approach, of the motion of a fractured glacier surface. Using these methods, a model is developed. The ability of this model to describe phenomena connected to crevasse opening is presented. The rupture of a large ice block from a hanging glacier is computed and analyzed. The regular acceleration of such an unstable ice block prior to its collapse is calculated and compared to the acceleration function obtained from observations. A good agreement between the two acceleration functions was found.

A quantitative assessment of the efficacy of an environmental enrichment programme for giant pandas

With the goal of enhancing psychological well-being, we developed an environmental enrichment programme for eight subadult and six adult giant pandas, Ailuropoda melanoleuca, at the Wolong Breeding Center in Sichuan, China. We used five different enrichment items, each selected because of the different behavioural opportunities they promoted: (1) manipulable plastic objects; (2) a burlap sack full of straw; (3) spruce branches; (4) a fruitcicle (apples frozen in a large ice block); and (5) a puzzle feeder. Each subject received each of the five items on three occasions, for a total of 15 enrichment sessions over the course of the 2.5-month study period. Each enrichment session was paired with a control session in which no enrichment was present. Pandas spent significantly more time active, and displayed a greater variety of object- and nonobject-directed behaviours when enrichment was present. We also found a statistically significant reduction in the rate of and percentage of time engaged in the performance of stereotypic behaviour and behaviours indicative of feeding anticipation. This effect was maintained even when pandas were not interacting directly with an enrichment item, suggesting that enrichment had a motivational carry-over effect in the aftermath of interactions with enrichment items. These results are consistent with the ethological needs model of motivation in that opportunities to perform more natural behaviour appeared to improve motivational indices of well-being. The pandas remained responsive to enrichment across the 15 trials, providing no evidence for habituation or cross-habituation. Age proved to be an important determinant of responsiveness; for example, adults, but not subadults, displayed a significant preference for feeding enrichment. Future studies will assess whether these promising initial results are maintained throughout the lives of captive giant pandas.

Mass dependence of energy loss in collisions of icy spheres: An experimental study

By varying the mass of icy spheres which collide with large ice blocks, we have determined the mass dependence of energy loss in such collisions. We find, at commercial deep freeze temperatures, that collisions at 1 cm/s become quite inelastic for small iceballs and that the rate at which elasticity decreases with decreasing mass roughly coincide with that predicted by a viscous dissipation model. If such a mass dependence persists at much lower temperatures, it could lead to very large effects in planetary ring systems (rings and dust, ice, surfaces, origin, and evolution).

Validation of backscatter models for level and deformed sea-ice in ERS-l SAR images

Abstract Backscatter models for level and deformed ice are evaluated based on in situ measurements of Baltic sea-ice and the resuhs are compared with coincident ERS-I Synthetic Aperture Radar (SAR) data. A two-layer scattering model is used for level ice with a dry snow cover. The resuhs show that ice surface scattering dominates in the pack ice, while scattering from the ice-water interface and ice volume scattering are important in the fast ice where the salinity is very low. For deformed ice which consists of large ice blocks, a two-component model is formulated and shown to be independent of the block size distribution. By evaluating the model based on in situ data it is concluded that specular reflections dominate, whereas the small-scale roughness is of less importance. An approach for data inversion is also described, which estimates the ice surface roughness from ERS-l SAR images during dry snow conditions.

Model tests on ice-rubble size and ship resistance in ice rubble

Described here are the results of model tests on resistance to ship-hull motion through a thick layer of ice rubble; layer thickness was 45% of hull draft. The tests were aimed to elucidate the influences of ice-rubble size on ice-rubble resistance. It was found that as ice-rubble size increased so did the resistance encountered by the test hull. However, it was also found that a layer of mush ice produced a greater resistance than did layers comprised of ice blocks. A layer comprised of both mush ice and ice blocks produced a resistance intermediate to layers comprised of either mush ice or ice blocks. Ship resistance generally increased with increasing ship speed. However, the influences of ship speed and ice-rubble size on the contributing resistance processes were found to be somewhat more complex. For example, the frictional resistance experienced by the parallel midbody of the test hull initially decreased with increasing ship speed, when the ice rubble was comprised of ice blocks which were small compared to layer thickness and hull size. The frictional resistance subsequently increased then decreased again with increasing ship speed. When the layer was comprised of relatively large ice blocks, frictional resistance increased to a maximum value then decreased with increasing ship speed. Generally, larger frictional resistance occurred for the layers comprised of larger ice rubble. In accordance with the relative sizes of ice rubble and ship hull, and with hull speed, the variations in frictional resistance can be explained in terms of a layer behaving as either a granular medium or as a viscous fluid. An additional aim of the study was to verify the existence of a thrust due to the ascension of submerged ice at a hull's stern. The existence of a stern thrust had been postulated by Kitazawa and Ettema (1985). The present study indicates that a relatively weak stern thrust may occur, but its magnitude is negligibly small compared to other resistance forces.

Experiments involving melting of a large ice block towed in sea water

Sonar performance in arctic regions, protection of arctic oil rigs, transportation of icebergs for fresh water, and iceberg life and track prediction require knowledge of the melting rates of fresh water ice moving in sea water. Melting rates were measured by towing a large ice block at a speed of approximately 1 knot in Monterey Bay, California. Scaling of the ice block as a model for an antarctic tabular iceberg was considered. For an ice block with a length of 16 feet, melting rates ranging from 27.5 in/hour at the bow to 8.1 in/hour at the stern were observed in one test for the following conditions: sea water temperature, 61°F; average tow velocity, 1.5 ft/sec; and a turbulent boundary layer. Ice ripples were observed along the sides of the ice block, and the wavelength is predicted satisfactorily using Re λ = 62000. Temperature was measured in the wake behind a large ice block during the towing; the measurements supported a tandem tow of two large ice blocks. The concept is that the lead ice block is a sacrificial source of cold water to protect the rear ice block. The front ice block melted at a 20 per cent faster rate.