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  • Wissenschaftspark Albert Einstein  (22)
  • Domstiftsarchiv
  • Fachstelle Brandenburg
  • GB Grünheide
  • Cold Regions Research and Engineering Laboratory 〈Hanover, NH〉  (22)
  • 1
    UID:
    kobvindex_GFZ122975
    Format: iv, 18 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 331
    Content: CONTENTS: Preface. - Introduction. - An overview of the model structure and operation. - Operation of subroutines. - TSTART. - FOMO. - REAWEA. - SEARCH. - STEMP. - TUNPIC. - Development history of the simulator. - The simulation of snow fence effects. - Urbanization and meltout. - Conclusion. - Literature cited. - Appendix A: Mathematical notation. - Appendix B: Computerprogram. - Abstract.
    Content: An annual snow-soil simulator for Arctic tundra was developed using coupled models of surface equilibrium temperature and substrate thermal diffusion. Snow ripening, melt and accumulation are modeled in the simulator which is forced with daily weather data. The simulator predicts that a snow fence array capable of producing drift deeper than 4.2 meters will initiate a permanent snowfield at Barrow, Alaska. Such a man-induced snowfield could serve as a reliable source of fresh water for Barrow and similar villages in the North Slope region of Alaska. Further analysis indicated that albedo reduction due to dust fall, snow removal, etc., is dominant over aerodynamic effects in producing the early spring meltout observed at Barrow Village.
    Note: MAB0014.001: ZSP-202-331 , Online frei verfügbar
    In: Research report
    Language: English
    Keywords: Forschungsbericht
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  • 2
    UID:
    kobvindex_GFZ20190423125151
    Format: v, 26 Seiten , Illustrationen
    Series Statement: CRREL Report 82-38
    Content: Extreme cold causes heavy buildup of frost, ice and condensation on many windows. It also increases the incentive for improving the airtightness of windows against heat loss. Our study shows that tightening specifications for Alaskan windows to permit only 30% of the air leakage allowed by current American airtightness standards is economically attractive. We also recommend triple glazing in much of Alaska to avoid window icing in homes and barracks. We base our conclusions on a two-year field study of Alaskan military bases that included recording humidity and temperature data, observing moisture accumulation on windows and measuring airtightness with a fan pressurization device.
    Note: Contents Abstract Preface Nomenclature Introduction Previous work in cold weather window performance Investigation Data acquisition and analysis Modeling the window thermal regime Moisture and ice observations Airtightness testing and analysis Annual heat loss from air leakage Results and conclusions Moisture on windows Airtightness Airtightness economics Recommendations for windows in extreme cold Airtightness Multiple glazing Literature cited Appendix A: Moisture levels and airtightness Appendix B: Dewpoint data Appendix C: Sample observations of icing
    In: CRREL Report, 82-38
    Language: English
    Keywords: Forschungsbericht
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  • 3
    UID:
    kobvindex_GFZ20190417111010
    Format: 68 Seiten , Illustrationen
    Series Statement: CRREL Report 82-34
    Content: The ice discharge through an opening in an ice control structure was documented to be a function of the floe size, ice type, ice floe conditions and vessel direction. The model data for the average ice discharge per vessel transit scaled to prototype values compared favorably with data taken at the St. Marys River ice control structure (ICS). The model results of the force measurements were also consistent with data taken at the St. Marys ICS. The dynamic loading conditions were independent of vessel direction. The dynamic loading to the structure using 3 types of ice (plastic, natural and urea-doped) showed a considerable difference in their means and standard deviations. The urea-doped ice was evaluated for dynamic loading conditions, and reasonable peak values of 3 to 5 times the mean load at each measuring position were recorded, independent of vessel direction. It appears that synthetic random ice floes may be used in model studies where ice discharge through an opening in a structure needs to be documented. This study shows the synthetic random ice floe discharge to fall reasonably within the values obtained for natural ice discharge for both rafted and non-rafted ice fields above the ICS. However, the question of whether synthetic ice can be used for analyzing force distributions and dynamic force loading criteria cannot be fully answered at this time because the load distributions of the synthetic and natural floes appear to differ.
    Note: CONTENTS Abstract Preface Introduction Scope of work Ice discharge from Lake Huron into St. Clair River Water velocity profiles at Port Huron Ice conditions Physical model Basis for selection Description Instrumentation Model ice control structure Open water calibration Open water tests Experimental procedures and techniques Ice cover calibration Ice control structure orientation Analysis of ice discharge due to ship transits Natural ice Synthetic ice Forces on the ice control structure Static measurements Dynamic force measurements Potential additional shear stresses Anticipated ice conditions with ICS Conclusions Literature cited Appendix A. Application of model results Appendix B. Suggested additional studies Appendix C. Derivation of ice discharge
    In: CRREL Report, 82-34
    Language: English
    Keywords: Forschungsbericht
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  • 4
    UID:
    kobvindex_GFZ20200318144344
    Format: v, 27 Seiten , Illustrationen
    Series Statement: CRREL Report 82-9
    Content: This study deals with the distribution of forces along the converging boundaries of the Port Huron, Michigan, region where unconsolidated ice in Lake Huron is held against wind and water stresses. An experimental basin was built to induce uniform shear stress on the model ice cover by flowing water beneath the ice. The boundary segments, which held the ice cover in the region, were instrumented to measure force in the normal and tangential directions. The distribution of normal forces along the boundary was compared with as distribution derived by using a theoretical model. An ice control structure (ICS) was installed in the basin and experiments were conducted to measure the forces on the ICS and the ice release through the opening in the ICS during simulated ship passages. The experimental results are presented in a nondimensional form. In addition, the force per unit length on the ICS and the area of ice released through its opening were estimated for the expected wind conditions at the Port Huron site.
    Note: CONTENTS Abstract Preface List of symbols Introduction Theoretical models Case 1 Case 2 Case 3 Experimental program Experimental facility Scaling factors Experimental results Analysis of wind data for lower Lake Huron Summary and conclusions Release of ice through the opening of an ICS Ice forces on the ice control structure Ice forces on ice control structure from a large unconsolidated ice cover Literature cited Appendix A. Equation for the stress resultants and velocities of the ice cover Appendix B. Monthly summary of wind data at Port Huron
    In: CRREL Report, 82-9
    Language: English
    Keywords: Forschungsbericht
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  • 5
    UID:
    kobvindex_GFZ122977
    Format: v, 37 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 329
    Content: CONTENTS: General Introduction. - Part I. Spatial and temporal variations in sea ice deformatfon. - Introduction. - Approach. - Site location and data collection procedures. - Data analysis. - Strain results. - Comparison of mesoscale deformation with macroscale deformation. - Nature of the ice pack rotation. - Conciusion. - Literature cited. - Part Il. Comparison of mesoscale strain measurements with linear drift theory predictions. - Introduction. - List of symbols. - Linear drift equations. - Ice drift solutions. - Comparison of theory with mesoscale measurements. - A more general linear constitutive law. - Conclusions. - Literature cited. - Appendix Relative magnitudes of differential drift forces. - Abstract.
    Content: Measurements of mesoscale sea ice deformation over a region approximately 20 km in diameter were made over a five-week period in the spring of 1972 at the main AIDJEX camp in the Beaufort Sea. They have been analyzed to determine nonlinearities in the ice velocity field (due to the discrete small-scale nature of the ice pack), as well as a continuum mode of deformation represented by a least squares strain rate tensor and vorticity. The deformation rate time series between Julian day 88 and 113 exhibited net areal changes as large as 3% and deformation rates up to 0.16% per hour. In the principal axis coordinate system, the strain rate typically exhibited a much larger compression (or extension) along one axis than along the other. Persistent cycles at ~12-hour wavelengths were observed in the divergence rate. A comparison of the average residual error with the average strain rate magnitude indicated that strains measured on a scale of 10 km or greater can serve as a valid measure of the continuum motion of the sea ice. This conclusion is also substantiated by a comparison between the mesoscale deformation, and macroscale deformation measured over a ~100-km-diameter region. Vorticity calculations indicate that at low temporal frequencies ( 〈 0.04 hr^-1 ) the whole mesoscale array rotates essentially as an entity and consequently the low frequency vorticity can accurately be estimated from the rotation of a single floe. (Part I) A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicated that the ice divergence rate and vorticity followed the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds, the divergence rate was negative with the vorticity being counterclockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior agreed with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen for pack ice. The best least squares values of the constitutive law parameters [Eta] and [Zeta] were found to be given by ~10^12 kg sec^-1. Using typical divergence rates, these values yielded compressive stresses of the magnitude of 10^5 N m^-1, which are similar to values suggested by the Parmerter and Coon ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer). Calculations were also carried out using a more general linear viscoelastic constitutive law that includes memory effects and that includes a generalized Hooke's law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates, overall, a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated "viscosities" similar to the Glen law behavior at temporal frequencies less than ~0.01 hr^-1 (Part II)
    Note: MAB0014.001: ZSP-202-329 , Online frei verfügbar
    In: Research report
    Language: English
    Keywords: Forschungsbericht
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  • 6
    UID:
    kobvindex_GFZ106218
    Format: vi, 12 Seiten , Illustrationen
    Series Statement: CRREL Report 78-4
    Content: The use of radio-echo sounding records to indicate the presence of internal layers within large ice sheets is of interest to glaciologists because it offers a means of tracking the internal properties of the ice sheets over large distances. The interpretation of the reflections obtained in this manner is more valuable, however, if a physical property change relating to the glaciological regime can be related to the dielectric property change producing the radio-echo reflections. In this report, we use the measured physical properties of core to bedrock taken at Cape Folger, East Antarctica (66 deg 22 min s, 111 deg (E), 324-m depth), to compute a profile of dielectric properties and from this, a depth-reflection coefficient profile for comparison with observed radio-echo reflections. The measurements available on physical properties are: density variations, bubble size and shape changes, and crystal fabric variations. The depths of the strong reflections shown on the available radio-echo records are in reasonable agreement with the depths corresponding to the highest reflection coefficients computed from the combined physical property measurements. In calculations to differentiate the separate effects of different physical properties, it appears that density variations account for the primary contributions to the calculated dielectric property changes corresponding to the highest reflection coefficients. However, bubble changes alone can also account for reasonable, though lower, reflection coefficients at the appropriate depths. Crystal fabric variations correspond poorly with the reflection locations. Density variations are normally associated with depositional events in the history of the ice sheet.
    Note: MAB0014.001: ZSP-201-78/4 , CONTENTS Abstract Preface Nomenclature Introduction Derivation of the power reflection coefficient-depth variation Possible sources of dielectric constant variation with depth in ice sheets Ice density variations Effect of macroscopic impurity layers Effect of microscopic impurtty layers Changes in inclusion geometry Effect of crystal orientation changes Physical properties of the Cape Folger core Density-depth profile Air bubble-geometry depth profile Crystal orientation-depth profile Radio-echo sounding data Results and conclusions Literature cited
    In: CRREL Report, 78-4
    Language: English
    Keywords: Forschungsbericht
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  • 7
    UID:
    kobvindex_GFZ106407
    Format: iii, 11 Seiten , Illustrationen
    Series Statement: CRREL Report 77-18
    Content: Abstract: Models originally developed to describe the arching and the movement of granular materials through hoppers or chutes are applied to the arching and drift of pack ice in straits and gulfs having lengths of 50 to 500 km. Verification of the usefulness of the models is attempted by making comparisons with ice deformation patterns as observed via satellite imagery in the Bering Strait region and in Amundsen Gulf. The results are encouraging in that there is good correspondence between observed arching and lead patterns and those predicted by theory. In addition, values determined via the model for the angle of internal friction (≈ 30° to 35°) and the cohesive strength per unit thickness (≈ 2000 N/m) are similar to values obtained by other approaches. It is estimated that if the wind velocity parallel to the Bering Strait exceeds ≈ 6 m/s, there will be ice flow through the strait.
    Note: MAB0014.001: ZSP-201-77/18 , CONTENTS Abstract Preface Introduction Theory Limiting span of an arch Flow of pack ice through converging channels Stoppage of flow Applications St. Lawrence Amundsen Gulf Bering Strait Conclusion References
    In: CRREL Report, 77-18
    Language: English
    Keywords: Forschungsbericht
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  • 8
    UID:
    kobvindex_GFZ123110
    Format: vi, 111 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 297
    Content: CONTENTS: Preface. - Abstract. - Introduction. - Glenn Creek watershed. - Location. - Topography. - Geology, soils and permafrost. - Climate. - Vegetation. - Data collection. - Precipitation. - Stream flow. - Air temperature and relative humidity. - Water temperature. - Evaporation. - Snow surveys. - Depth of thaw. - Dissolved solids. - Hydrology. - Introduction. - General channel description. - Hydraulic geometry. - Characteristics of hydrographs. - Sources of streamflow. - Attempts at flow separation. - Hydrograph modeling. - Summary and conclusions. - Literature cited. - Appendix A: Summary of permafrost probe observations, Glenn Creek watershed.. - Appendix B: Water-holding and-transmitting properties of moss. - Appendix C: Summary of hydraulic geometry data from 1964 discharge measurements. - Appendix D: Summary of data used in computing recession constants.
    Content: The results of a four-summer (1964-1967) hydrologic study of the watershed of Glenn Creek, about 8 miles north of Fairbanks, Alaska, in the Yukon-Tanana uplands physiographic province, are presented. This work was initiated to provide initial baseline hydrologic data for a small subar ctic watershed, the first of its kind in North America. Standard hydrologic and meteorologic instrumentation was used, and streamflow characteristics were analyzed by standard hydrograph-analysis techniques. The stream is second-order, and drains an area of 0.70 square mile. Basin elevations are from 842 ft to 1618 ft. In regard to topography, geology, soils, permafrost, vegetation, and climate, the watershed seems to be representative of low-order, low-elevation drainage basins in the province. Analysis of rainfall-runoff data indicates that about half the 12.3-in. normal annual precipitation is runoff. The remainder is the actual evapotranspiration , which equals only about 30% of estimated potential evapotranspiration. For individual storms, runoff/rainfall proportions were from 0.03 to 0.42 and were positively correlated with antecedent discharge of the stream, which is a measure of watershed wetness. The stream responds rapidly to rainstorms except when the basin is very dry, and has markedly slow recessions compared with temperate region streams of similar size. Rate of recessions is apparentlv controlled by concurrent evapotranspiration rates. Analysis of hydrographs and knowledge of the physical characteristics of the basin indicate that storm runoff occurs initially as surface runoff from bare soil areas adjacent to the stream, while recessions are dominated by a combination of tunnel flow beneath moss-covered parts of the basins and typical groundwater flow through the moss and soils. Peak discharges for individual storms could be well estimated by an equation including antecedent discharge, total precipitation and storm duration, and average recession constant. These results represent the first detailed hydrologic data from the discontinuous permafrost zone of the North American taiga and should be of significance to the International Hydrological Decade and International Biological Program.
    Note: MAB0014.001: ZSP-202-297 , Online frei verfügbar
    In: Research report
    Language: English
    Keywords: Forschungsbericht
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  • 9
    UID:
    kobvindex_GFZ123550
    Format: v, 83 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 262
    Content: CONTENTS: Introduction. - Regional setting. - General description and topography. - Geology. - Soils. - Climate. - Precipitation. - Temperature. - Weather during period of study. - Vegetation. - Hydrology. - Water balance. - Introduction. - Yield. - Precipitation. - Loss of glacial storage. - Evapotranspiration. - Summary. - Flow variability. - Flow-duration curves. - Flood estimation. - Response to rain and meltwater. - Water quality. - Introduction. - Suspended sediment. - Bedload. - Dissolved sediment. - Water temperatures. - Channel shape and process. - General characteristics of braided channels. - Channel material. - Channel shape. - Channel changes. - Introduction. - Channel profiles. - Ground photography. -Vertical aerial photography. - Freeze-up and breakup. - Summary. - Literature cited. - Selected bibliography. - Appendix A: Measurement site locations and methods. - Appendix B: Installation of water-level recorder. - Appendix C: Delta river quicksilts - properties and mode of formation. - Appendix D: Channel shape data. - Abstract.
    Content: A one-year reconnaissance study was made of a large braided glacial river and its drainage basin (drainage area 1665 m^2; elevation range 1000 - 10,000 ft) for which a minimum of hydrometric and meteorologic data existed. The report includes estimates of the water balance, flow-duration curves, and sediment characteristics, and descriptions of stream response to glacial melt and rain, channel geometry and channel processes. Mean annual basin precipitation is estimated at 40.4 in. and mean annual loss of permanent glacial storage is about 1 in. About 30% of this leaves the basin as evapotranspiration, 50% as stream flow, and 20% as groundwater flow. Characteristics of response to glacial melt are outlined. Flow peaks near the mouth occur within 24 hours of rainfall Greater than 0.5 in./day at foothills meteorological stations; rains of less than that amount do not generally produce discernible stream response. Stream channel geometry is described in detail. Most channels on the lower floodplain are asymmetrical and are roughly triangular or parabolic, and have high width/depth ratios. At-a-station hydraulic geometry is described. Surveys and gr ound and aerial photography are used to describe channel changes.
    Note: MAB0014.001: ZSP-202-262 , Online frei verfügbar
    In: Research report
    Language: English
    Keywords: Forschungsbericht
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  • 10
    UID:
    kobvindex_GFZ20190702105959
    Format: vi, 47 Seiten , Illustrationen
    Series Statement: CRREL Report 84-33
    Content: A small-scale experimental study was conducted to characterize the magnitude and nature of ice forces during continuous crushing of ice against a rigid, vertical, cylindrical structure. The diameter of the structure was varied from 50 to 500 mm, the relative velocity from 10 to 210 mm/s, and the ice thickness from 50 to 80 mm. The ice tended to fail repetitively, with the frequency of failure termed the characteristic frequency. The characteristic frequency varied linearly with velocity and to a small extent with structure diameter. The size of the damage zone was 10 to 50% of the ice thickness, with an average value of 30%. The maximum and mean normalized ice forces were strongly dependent on the aspect ratio (structure diameter/ice thickness). The forces increased significantly with decreasing aspect ratio, but were constant for large aspect ratios. The maximum normalized forces appeared to be independent of strain rate. The effect of velocity on the normalized ice forces depended on structure diameter. The mean effective pressure or specific energy of ice crushing depended on both aspect ratio and ice-structure relative velocity. The energy required to crush the ice for the one failure cycle was obtained from the ice force records for each test, and was compared to the energy calculated from an idealized sawtooth shape for the force record, the maximum force, velocity and characteristic frequency data. Originator - supplied keywords included: Cold regions, Cold regions construction, Cylindrical test structures, Ice, Ice crushing, Ice forces, and Test facilities.
    Note: Contents Abstract Preface Nomenclature Introduction Test objectives Experimental setup and procedures Facilities Test fixture Data acquisiton system Ice sheets Measurement of ice properties Daily test summary Experimental results and discussion Observations Ice force records Frequency of ice force variations Discussion Maximum crushing forces Mean effective pressure or specific energy of ice in crushing Failure energy of ice Ratio of maximum force to mean force Summary and conclusions Literature cited Appendix A: Data for continuous crushing tests
    In: CRREL Report, 84-33
    Language: English
    Keywords: Forschungsbericht
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