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  • Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory  (54)
  • Englisch  (54)
  • Russisch
  • 2010-2014
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  • Englisch  (54)
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  • 1
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/8
    In: CRREL Report, 77-8
    Beschreibung / Inhaltsverzeichnis: A broadbanded impulse radar system was used for aerial detection of accumulated frazil and brash ice in a 9.5-km reach of the St. Lawrence River near Ogden Island. The remote sensing and data reduction system developed for the project provided data sufficient for production of a contour map having 1-ft intervals. With this contour map, the accumulation pattern of frazil and brash ice could be analyzed. Recommendations are given for improving the performance of the aerial profiling system.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 19 Seiten , Illustrationen
    Serie: CRREL Report 77-8
    Sprache: Englisch
    Anmerkung: CONTENTS Page Abstract Preface Conversion factors: U.S. customary to metric (SI) units of measurement Background Objectives Profiling system Approach Profiling method Data reduction and interpretation Results Conclusions Recommendations Literature cited Appendix A. Comparison of ground and aerial data
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  • 2
    Signatur: ZSP-201-77/9
    In: CRREL Report, 77-9
    Beschreibung / Inhaltsverzeichnis: This report presents experimental results on the conditions of initiation of an ice jam by a simple surface obstruction, on the equilibrium thickness of an ice jam formed by accumulation and submergence of ice floes, and on the compression strength of floating, fragmented ice cover. In the study on ice jam initiation, it was found that the minimum concentration of floes in the opening of the obstruction at which a jam occurs is nearly independent of the ratio of width of constricted passage to channel width, and is proportional to a negative power of the ratio of floe length to width of constricted passage. From energy analysis of floe submergence, a relationship relating the thickness of a jam formed by accumulation and submergence of floes to the approach flow characteristics was derived and found to fit satisfactorily the experimental data. In experiments on compression strength of floating, fragmented ice cover it was found that the compressive strength is inversely proportional to compression velocity and independent of cover length.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vii, 45 Seiten , Illustrationen
    Serie: CRREL Report 77-9
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface List of symbols Introduction I. Initiation of ice jams by partial surface obstructions A. Introductory remarks B. Experimental apparatus and procedure C. Dimensional analysis D. Presentation of results and discussion ΙΙ. Thickness of ice jams due to accumulation and transport of ice floes A. Introductory remarks B. Experimental apparatus and procedures C. Presentation of results E. Conclusion III. Compressive strength of floating fragmented ice covers A. Introductory remarks B. Experimental setup and procedure C. Presentation of results and discussion D. Conclusions Literature cited Appendix A: Experimental results on ice jam initiation Appendix B: Effect of surface tension on submergence velocity of ice floes Appendix C: Experimental results for ice jam thickness study Appendix D: Experimental results on compressive strength of fragmented ice cover
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  • 3
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/31
    In: CRREL Report, 77-31
    Beschreibung / Inhaltsverzeichnis: Ten roofs in Concord, New Hampshire, were surveyed for wet insulation using a hand-held infrared camera. Suspected wet areas were marked on the roof with spray paint and roof samples were obtained to verify wet and dry conditions. Recommendations for maintenance and repair were made based on infrared findings, water contents, and visual examinations. An incremental economic study is presented to serve as a guide in determining the most cost-effective approach.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 29 Seiten , Illustrationen
    Serie: CRREL Report 77-31
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: US, customary to metric (SI) units of measurement Introduction Infrared camera Core samples State House State House Annex State Library Legislative Office Building Public Health Complex Highway Garage Fish and Game Offlces Supreme Court John O. Morton Building Department of Health and Welfare Laboratory Economics of roof reinsulation Conclusions and recommendations Literature cited
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  • 4
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/16
    In: CRREL Report, 77-16
    Beschreibung / Inhaltsverzeichnis: A brief discussion is given of the ways an icebreaker breaks ice. Since the icebreaking process is so complex, the solution of a mathematical model does not appear to be feasible. As an alternative, it is suggested that physical models be used to design icebreakers. The appropriate scaling laws for physical models are developed and their practical limitation discussed.
    Materialart: Schriftenreihen ausleihbar
    Seiten: ii, 9 Seiten , Illustrationen
    Serie: CRREL Report 77-16
    Sprache: Englisch
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  • 5
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/17
    In: CRREL Report, 77-17
    Beschreibung / Inhaltsverzeichnis: A literature search was made for information on the accretion of ice on ocean structures and on methods for control. The bulk of the reports were in Russian, with some additional Japanese, British, American, Canadian, and Icelandic sources. Analysis of icing reports indicated that sea spray is the most important cause of ship icing, with lesser amounts due to freezing rain, snow, and fog. Icing is a potential danger whenever air temperatures are below the freezing point of water and the sea temperature is 6 C or lower. Theoretical work on the ice accretion process is discussed, and a method is suggested, based on Russian experiments, for calculating the sea spray accumulation rate for cylindrical and flat surfaces as a function of water source temperature, air temperature, and wind speed. Other factors that influence icing severity are ship size and configuration, angle between ship course and water heading, and ship speed. Icing in the north temperate latitudes generally occurs in the rear of barometric depressions. Maps showing limits of various degrees of icing severity are included. Atmospheric icing measurements on tall land-based structures are presented, and potential maximum accumulations estimated. Control measures are discussed, though no completely effective method is available. Mechanical (impaction) methods are the most common, but experiments have been conducted on heated, icephobic, and deformable surfaces, and with freezing point depressants. No device for the unequivocal measurement of ice accumulation is available, though some experimental methods are suitable for controlled testing; it is recommended that a device be developed.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 42 Seiten , Illustrationen
    Serie: CRREL Report 77-17
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: U.S. customary to metric units of measurements Introduction The freezing proeess Icing observations Geographical distribution of icing and contributing meteorological conditions Extreme icing conditions Extremes of icc accumulation Prediction of icing occurrences Prediction of icing intensity and rate Control methods Measurement of icing rate Conclusions and recommendations Literature cited Appendix A. Maps of icing occurrence and rate Appendix B. Data for computing ship icing rates Appendix C. Estimation of ice accumulation
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  • 6
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/30
    In: CRREL Report, 77-30
    Beschreibung / Inhaltsverzeichnis: Abstract: Ageneral computer model to simulate municipal snow removal has been developed. Programs which aid in the routing of snowplows are a part of this package. Once vehicle routes are created, the simulation program can be used to assess situations varying both equipment and meteorological parameters. Time for each plow to complete its route is calculated. Considerations are made for the above variable parameters plus plowing windrow, route starting depth, overlapping truck routes and intersection delay time. The effects of storm length, snowfall rate and starting depth on total plowing time are examined in a test case.
    Materialart: Schriftenreihen ausleihbar
    Seiten: ii, 7 Seiten , Illustrationen
    Serie: CRREL Report 77-30
    Sprache: Englisch
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  • 7
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/21
    In: CRREL Report, 77-21
    Beschreibung / Inhaltsverzeichnis: Cold weather limits the successful application of built-up roofing, but often a roof installation must be completed late in the fall or in the winter. The loose-laid protected membrane roof with a synthetic sheet membrane can be installed in the middle of the winter with complete reliability. A synthetic membrane is traditionally more expensive than built-up roofing (rising crude oil prices, however, have reversed this condition), but it has two special features besides its suitability for winter installation: it can be placed on a damp deck, if necessary, and, being losse-laid, it does not split because of deck movement. This report documents information on the installation of two roofs in Anchorage, Alaska, during January and February 1972, including a discussion of the necessary snow removal from the bare deck and the use of portable shelters for preparing the lap joints between sheets during very cold weather. The winter installation caused no special construction problems and the advantages of the synthetic membrane make it an attractive alternative to built-up roofing. The cost of loose-laid protected membrane roofs in Alaska was, in 1972, nearly $300 per square ($28/sq.m), including insulation. Prices are rising as labor costs rise and as more insulation is specified.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 5 Seiten , Illustrationen
    Serie: CRREL Report 77-21
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction The protected membrane roof Winter construction considerations Construction costs Conclusion
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  • 8
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/28
    In: CRREL Report, 77-28
    Beschreibung / Inhaltsverzeichnis: Tests were conducted to assess the extent of surface degradation resulting from the application of non-chloride deicing chemicals on three types of airfield pavements. The chemicals tested were proprietary mixtures of urea, formamide, and ethylene glycol; sodium chloride, distilled water, and dry specimens were used as controls and for comparison. Pavements included new and old specimens of open-graded asphaltic concrete and old specimens of dense-graded asphaltic concrete. Portland cement concrete specimens used were new and old, with and without air-entrainment. New and old tar rubber concrete specimens were also tested. Samples were subjected to up to 60 freeze-thaw cycles with deicing chemicals flooding their upper surface. Each specimen was rated on a scale of 0-5 after every five freeze-thaw cycles. All PCC specimens showed some surface degradation, whereas the dense- and open-graded asphaltic concretes were largely unaffected.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 16 Seiten , Illustrationen
    Serie: CRREL Report 77-28
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: U.S. customary to metric (SI) Units of measurement Introduction Test procedure Pavement types Deicing chemicals Description of tests Discussion Literature cited Appendix A: Test results Appendix B: Portland cement concrete materials data
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  • 9
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/32
    In: CRREL Report, 77-32
    Beschreibung / Inhaltsverzeichnis: An experimental study of forced convective heat transfer over a vertical melting plate has been conducted. This study covers water velocities ranging from 1.7 to 9.8 mm/s and bulk water temperatures from 1.11 to 7.50 C. The experimental results are correlated in terms of Nusselt, Prandtl and Reynolds numbers with a moderate correlation coefficient of 0.843. The results are expected to be useful in predicting the heat transfer characteristics of a much larger prototype ice-water heat sink.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 12 Seiten , Illustrationen
    Serie: CRREL Report 77-32
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Summary Introduction Problem General review of the subject Experimental apparatus General considerations Water reservoir Test chamber assembly Pumping system Electrical control system Experimental procedure Experimental results Discussion and comparison of results Conclusions Literature cited
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  • 10
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/25
    In: CRREL Report, 77-25
    Beschreibung / Inhaltsverzeichnis: Results of a study to determine the feasibility of using an impulse radar to detect moisture variations in the built-up roof at CRREL and to monitor the curing of concrete are presented. The results indicate that impulse radar can be used to detect wide variations in roof moisture associated with built-up roof surface deterioration and that this technique has the potential of providing a nondestructive test method for measuring the strength of concrete during curing.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 9 Seiten , Illustrationen
    Serie: CRREL Report 77-25
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: U.S. customary to metric units of measurement Introduction Impulse radar system Results and discussion Conclusions and recommendations Literature cited ILLUSTRATIONS Figure Relative locations where impulse radar measurements were made andsamples for moisture determinations were obtained on the CRREL roof Impulse radar signal reflected from metal sheet resting on roof Impulse radar signal reflection from roof at station A Impulse radar surface reflection coefficient versus moisture contentofroof Impulse radar signal reflection from aluminum foil on bottom of con-crete form and from aluminum sheet metal resting on top of form Unconfined compressive strength of concrete versus time Examples of X-Y plots of impulse radar signals obtained during thesounding of concrete slab Impulse radar signal reflection coefficients versus time for acuring concrete slab Calculated impulse radar signal attenuation in concrete slab versuselapsed time Dielectric constants versus time calculated from impulse radar signalInformation obtained during curing of concrete slab Unconfined compressive strength of concrete versus corrected reflec-tion coefficient calculated from impulse radar signal data obtainedduring the curing of concrete slab TABLES Comparison of roof moisture content with radar surface reflection coefficient and dielectric constant
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  • 11
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/27
    In: CRREL Report, 77-27
    Beschreibung / Inhaltsverzeichnis: The spectral reflectance of natural snow in the range of 0.20- to about 0.40-micrometers wavelengths was studied in the laboratory using both continuous spectral scanning and fixed bandpass measurements. White barium sulfate pressed powder was used as a standard for comparison. The reflectance of fresh snow was found to be very high (usually nearly 100%) and only weakly wavelength dependent from 0.24 micrometers to the visible range. In the 0.20- to 0.24-micrometers portion of the spectrum, the reflectance was found to be quite erratic. Possible reasons for the irregularities in reflectance measurements are discussed.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 19 Seiten , Illustrationen
    Serie: CRREL Report 77-27
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Experimental procedure Snow collection Spectrophotometric methods Data analysis Potential sources of error Presentation of results Continuous-scan measurements Comparison of sequential bandpass and continuous-scan measurements Theoretical calculations Discussion of results Differences in amplitude of reflectance measurements Irregularities in the shape of spectral reflectance curves The true spectral reflectance of snow in the ultraviolet region Conclusions Literature cited Appendix A. Absolute reflectance values of pressed BaSO4 powder
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  • 12
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/23
    In: CRREL Report, 77-23
    Beschreibung / Inhaltsverzeichnis: This report discusses the relationship between an architect and a behavioral scientist. Some of the discussion applies to this cooperative work for design of buildings. The bulk, however, relates to the cooperation of architect and behavioral scientist while conducting research. Examples from collaborative research at Alaskan military installations are cited which demonstrate the roles and contributions of the two disciplines.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 8 Seiten , Illustrationen
    Serie: CRREL Report 77-23
    Sprache: Englisch
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  • 13
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/19
    In: CRREL Report, 77-19
    In: Mechanics of cutting and boring, Part VI
    Beschreibung / Inhaltsverzeichnis: Abstract: The report deals with forces and power levels in cutting machines having adisc or drum that rotates about an axis perpendicular to the direction of advance. The forces on individual cutting tools are related to position on the rotor and to characteristics such as tool layout, rotor speed, rotor size, machine advance speed, and rotor torque. Integration leads to expressions for force components acting on the rotor axis, taking into account tool characteristics, cutting depth of the rotor, and rotor torque. These provide estimates of tractive thrust and thrust normal to the primary free surface. For self-propelled machines, this leads to considerations of traction, normal reaction, weight and balance, and power/weight ratios. Specific energy consumption is analyzed and related to machine characteristics and strength ofthe material being cut. Power per unit working area is discussed, and data for existing machines are summarized. Power requirements for ejection ofcuttings are analyzed, and the hydrodynamic resistance on underwater cuttings is treated. A number of worked examples are given to illustrate the principles discussed in the report.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vii, 36 Seiten , Illustrationen
    Serie: CRREL Report 77-19
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Foreword Introduction Terminology Forces on individual cutters Torque force and tool force Forces on the rotor axis Tractive thrust and down thrust Alternative tool force formulations Vehicle traction Power/weight ratio Weight and balance Force, torque, speed and power Specific energy Efficiency and performance index Power density Power requirements for ejection of cuttings Hydrodynamic resistance in underwater cutting
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  • 14
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/18
    In: CRREL Report, 77-18
    Beschreibung / Inhaltsverzeichnis: 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.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 11 Seiten , Illustrationen
    Serie: CRREL Report 77-18
    Sprache: Englisch
    Anmerkung: 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
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  • 15
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/7
    In: CRREL Report, 77-7
    In: Mechanics of cutting and boring, IV
    Beschreibung / Inhaltsverzeichnis: The report deals with the cutting of rock and similar materials by parallel motion tools. It examines cutting forces and energy requirements, taking into consideration tool geometry, wear, operating conditions, and material properties. After an introductory discussion of terminology, some general principles are outlined, and relevant theoretical ideas on metal cutting and rock cutting are reviewed. The next section, which is the heart of the report, reviews experimental data on the magnitudes and directions of cutting forces. There is a graphical compilation of data, including some from obscure or unpublished sources. The variables covered include chipping depth, rake angle, relief angle, side rake, base angle, tool width, tool compliance, tool speed, tool wear, tool interactions, and material properties. The second major part of the report treats the energetics of cutting. It begins with a short discussion of relevant principles, and continues with a compilation and review of experimental data, covering the same independent variables as the force section. The report ends with a concise summary of general behavior for parallel motion tools.
    Materialart: Schriftenreihen ausleihbar
    Seiten: xi, 85 Seiten , Illustrationen
    Serie: CRREL Report 77-7
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Foreword Introduction Terminology Principles of cutting Forces acting on a single cutter Theoretical Ideas on cutting Experimental data on cutting forces Effect of chipping depth on tool forces Effect of rake angle on tool forces Effect of relief angle on cutting forces Effect of side rake on tool forces Effect of base angle or face profile on tool forces Effect of rounding at the cutting edge Effect of tool width on cutting forces Tool compliance and force fluctuations Effect of tool speed on cutting forces Effect of rock properties on cutting forces Tool interaction and kerf spacing Effect of multiple pass cutting on tool forces Effect of tool wear on cutting forces Development of wear Energetics of cutting Energetics of parallel-motion tools Variation of specific energy with chipping depth for a single tool Effect of rake angle on specific energy Effect of relief angle on specific energy Effect of side rake on specific energy Effect of base angle or face profile on specific energy Effect of tip radius on specific energy Effect of tool width on specific energy Effect of tool speed on specific energy Variation of specific energy with rock properties Effect of kerf spacing on specific energy Effect of multiple pass cutting on specific energy Effect of tool wear on specific energy General summary Literature cited Appendix Α. Additional data for ice Appendix Β. Conversion factors: U.S. customary and metric units of measurement
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  • 16
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/12
    In: CRREL Report, 77-12
    Beschreibung / Inhaltsverzeichnis: A computer program to calculate the increased live load on a snow-covered roof due to rain-on-snow is given. For the 25-year rainstorm falling on a heavy snow load on a flat roof in Hanover, New Hamsphire, and additional 98 kg/m2 (20 lb/ft2) of liquid water is added to the live load. The additional load due to rain-on-snow is very sensitive to the snow properties and characteristics of the roof. A wide range of live loads is possible, depending on the particular circumstances.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vii, 19 Seiten , Illustrationen
    Serie: CRREL Report 77-12
    Sprache: Englisch
    Anmerkung: CONTENTS Page Abstract Preface Summary Nomenclature Introduction Water movement through snow Vertical percolation Lateral flow Flat roofs Sloping roofs Rainfall intensity-duration effects Miscellaneous effects Radial flow to drains Flow along gutters on snow-covered roofs Snow structure Basal layer Conclusion Literature citied Appendix A. Computer program calculating roof loads from rain-on-snow
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  • 17
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/14
    In: CRREL Report, 77-14
    Beschreibung / Inhaltsverzeichnis: The breakup of the Chena River was observed and documented during the spring of 1975 and 1976. This study attempted to determine the potential for damage to the proposed Chena River flood control dam from ice and debris during breakup. Results of this study were compared to those of a 1974 companion study. In 1975, ice thickness were determined to be 15% thinner than in 1974 and ice volume was 33% smaller. No major ice floes were observed in 1975 and no significant flooding occurred, although the approaches to a bridge at the damsite were eroded by debris and high water immediately after breakup. The 1976 breakup was milder than that of 1975. Minor flooding in the lower river was caused by jamming of a few large ice pieces, but no property damage resulted.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 44 Seiten , Illustrationen
    Serie: CRREL Report 77-14
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Summary Introduction Ice thickness and quantity Chronology of the 1975 Chena River breakup Checkpoint 3 Checkpoint 4 Checkpoint 5 Checkpoint 6 Checkpoint A Checkpoint 7 Checkpoint C Checkpoint D Checkpoint 8 Checkpoint 10 Checkpoint 11 Checkpoint 12 Spring flooding and debris The 1976 Chena River breakup Breakup in other years Summary and conclusions Appendix A. Sequential photographs of 1975 breakup at checkpoints 3-12
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  • 18
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/15
    In: CRREL Report, 77-15
    Beschreibung / Inhaltsverzeichnis: A laboratory experimental study was conducted on a scale model of an annular flow ice-water heat sink to be used to store the waste heat produced in a hardened defense installation operating in an isolated mode. The study ex­amined: 1) scaling relationships for predicting the performance of prototype units using data from scale models, 2) the accuracy of a computer prediction technique developed during an earlier study, 3) the heat transfer phenom­enon at the ice-water interface, and 4) some practical aspects related to the operation of a prototype installation. The scaling relationships and the computer program were found to be sufficiently accurate for use in developing a proto­type sink design. During operation the scale model sink provided an almost constant low temperature source of coolant water for approximately one-half its useful life and thereafter behaved like an ordinary stored water reservoir type heat sink. No significant operational problems were discovered.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vii, 54 Seiten , Illustrationen
    Serie: CRREL Report 77-15
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Conversion factors: U.S. customary to metric units of measurement Introduction Description of experiment Apparatus Test procedure Experimental results Summary of experimental tests Influence of coolant water flow rates Approximation of the rate of melting Comparison of experimental and computed results Comparative analysis of the model sinks Approximation of the heat transfer coefficient Conclusions and recommendations Literature cited Appendix A. Experimental data, heat sink Model II Appendix B. Heat sink scaling and similarity relationships Appendix C. Derivation of the relationships for the heat transfer coefficient, Reynolds and Nusselt numbers Appendix D. Determination of freezing rates and refrigeration loads Appendix E. Approximation of stresses in the heat sink tank
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  • 19
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/11
    In: CRREL Report, 77-11
    Beschreibung / Inhaltsverzeichnis: Two performance indicators, effectiveness and thermal efficiency, are defined and used to evaluate the year-round performance of three protected membrane roofs in Alaska and New Hampshire. Effectiveness is a measure of the deviations of ceiling temperatures from a yearly average, with large diviations indicating erratic performance in the roofing-insulation system and small departures indicating a thermally stable system. Thermal efficiency, the ratio of calculated heat loss to measured heat loss, is affected by climatic conditions such as rain, snow, solar radiation and wind. Thermal efficiency values of 100% or greater are possible since the calculated heat loss is based only on the inside and outside air temperature differences and the thermal properties of the roof components. Results of the year-round evaluation indicate that the three protected membrane roofs generally have high values of both effectiveness and thermal efficiency.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 40 Seiten , Illustrationen
    Serie: CRREL Report 77-11
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: U.S.customary to metric (SI) units of measurement Introduction Location of test sites Fairbanks Anchorage Hanover, N.H. Test program Instrumentation Effectiveness Therma lefficiency Heat balance within the roof Comparisons with conventional systems Conclusions Effectiveness of the test roof Thermal efficiency Heat balance within the roof Applicability Recommendations Literature cited Appendix A. Temperature and heat flow measurements, Anchorage and Fairbanks, Alaska, and Hanover, New Hampshire Appendix B. Thermal efficiencies of the test roof, Anchorage and Fairbanks, Alaska, and Hanover, New Hampshire Appendix C. January 1973 and August 1972 comparisons of protected membrane and conventional built-up membrane systems at Hanover, New Hampshire
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  • 20
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/10
    In: CRREL Report, 77-10
    Beschreibung / Inhaltsverzeichnis: Abstract: The amount of force that an ice sheet can apply to a vertical pile was tested by lowering a hydraulic ram device into a hole cut in an existing ice sheet. The device had a large base and shoved a relatively narrow vertical pile in a horizontal direction. Test variables were: pile widths - 1.5 in. to 36.7 in.; pile shapes - flat, round, 45 ° and 90° wedges; ice thickness - 2.6 in. to 8.8 in.; and ram speed - 0.07 in./sec to 18.75 in./sec; but not all shapes and sizes were tested at all speeds. Air temperature was 20 ° F (-6.7 ° C). Forces and displacements were measured electronically. The findings are presented as a table of test results and as bar graphs of the resultant ice pressures versus the pile width-to-ice-thickness ratio, pile width and shape combination and pile velocity. The types of failures in the ice sheet were classified as crushing, splitting, buckling, bending, and creeping. The ice sheet generally withstood a high initial load followed by several lower peak load levels. The maximum ice pressure measured was 610 psi for a 12.6-in.-diam round pile in 8.4-in.-thick ice.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 9 Seiten , Illustrationen
    Serie: CRREL Report 77-10
    Sprache: Englisch
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  • 21
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/29
    In: CRREL Report, 77-29
    Beschreibung / Inhaltsverzeichnis: Results of measurements of salinity, grain size, substructure dimensions and crystal fabrics of the undeformed 2.15-m-thick annual sea ice sheet near Narwhal Island, Alaska, are presented. A notable observation was the formation of a dominant c-axis horizontal structure in all ice below 14 cm, including transformation to a pronounced east-west alignment of the c-axes by a depth of 66 cm. This study confirms earlier reports of the occurrence of very strong horizontal c-axis alignments in arctic fast ice.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 8 Seiten , Illustrationen
    Serie: CRREL Report 77-29
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Sampling and analytical procedures Results Discussion Conclusions Literature cited
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  • 22
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/26
    In: CRREL Report, 77-26
    Beschreibung / Inhaltsverzeichnis: A theory for ice forces acting on inclined wedges has been developed, thus making it possible to predict the magnitude of the intermittent ice forces from knowledge of the physical parameters of the system. The theory has been verified by model tests with artificial and natural ice.
    Materialart: Schriftenreihen ausleihbar
    Seiten: viii, 26 Seiten , Illustrationen
    Serie: CRREL Report 77-26
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface List of symbols Summary Introduction Recent ice research in Denmark General Structures with vertical faces Wedges with inclined faces Recording of the strength of natural ice Artificial ice — properties and manufacture General Composition of material Order of mixing ingredients Rupture theory Theoretical approach Initial contact Forces acting on wedge Maximum force and actual force Principal stress equations 8Dynamic equations Intermittent nature of force Theoretical curve Verifiction of theory by model tests Description Width of rupture channel Plotting of results Engineering application Comparison with Korahavin’s results Recommendations for future research References Appendix A
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  • 23
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/13
    In: CRREL Report, 83-13
    Beschreibung / Inhaltsverzeichnis: A review on past experimental and theoretical work indicates a need for additional experimentation to characterize the response of snow to inelastic pressure waves. Pressure data from previously conducted explosion tests are analyzed to estimate the elastic limit of snow of 400 -kg/cu m density to be about 36 kPa. This pressure corresponds to a scaled distance of 1.6 m/cu.rt.kg for charges fired beneath the surface of the snow, and to a scaled distance of 1.2 m/cu.rt.kg for charges fired in the air. The effects of a snow cover on the method of clearing a minefield by using an explosive charge fired in the air above the snow surface are also discussed and recommendations are given for further work in this area. Explosive pressure data are used to estimate the maximum effective scaled radius for detonating buried mines at shallow depth to be 0.8 m/cu.rt.kg. Fuel-air explosive will increase this effective radius significantly because of the increase in the size of the source region.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 33 Seiten , Illustrationen
    Serie: CRREL Report 83-13
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface List of symbols Introduction Objectives Background Problems in describing the response of snow to an applied stress Methods of determining the dynamic behavior of materials Review of previous studies on snow Experimental measurements on snow Summary of snow experiments Theoretical studies Confirmation of the theory Discussion Applications Recommendations Summary Literature cited Appendix A. Selected data from Wisotski and Snyder (1966) Appendix B. Pressure data from Livingston (1964)
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  • 24
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/14
    In: CRREL Report, 83-14
    Beschreibung / Inhaltsverzeichnis: An analysis of ice fracture that incorporates dislocation mechanics and linear elastic fracture mechanics is discussed. The derived relationships predict a brittle to ductile transition in polycrystalline ice under tension with a Hall-Petch type dependence of brittle fracture strength on grain size. A uniaxial tensile testing technique, including specimen preparation and loading system design was developed and employed to verify the model. The tensile strength of ice in purely brittle fracture was found to vary with the square root of the reciprocal of grain size, supporting the relationship that the theory suggests. The inherent strength of the ice lattice and the Hall-Petch slope are evaluated and findings discussed in relation to previous results. Monitoring of acoustic emissions was incorporated in the tests, providing insights into the process of microfracture during ice deformation.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 43 Seiten , Illustrationen
    Serie: CRREL Report 83-14
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Background Development of testing technique Test specimens Tensile testing Compression testing Experimental results Tensile tests Compression tests Discussion Conclusions Suggestions for further work Literature cited Appendix A: Additional information on seed grains Appendix B: Thin-sectioning procedure Appendix C: Displacement transducer calibration
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  • 25
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/16
    In: CRREL Report, 83-16
    Beschreibung / Inhaltsverzeichnis: The presence of snow on the ground can impose limitations on the mobility of wheeled and tracked vehicles. Snow depth and density are the two most easily measured snow properties that can be related to mobility over snow. Existing models of snowpack accumulation and ablation processes and models of internal snowpack structure were examined to determine if a model of the snowpack can be developed for use in predicting the snow parameters that affect mobility. Simple models, such as temperature index models, do not provide sufficient snowpack details, and the more detailed models require too many measured inputs. Components of the various models were selected from a basis of a snowpack model for predicting snow properties related to mobility over snow. Methods of obtaining the input data from some components are suggested, and areas where more development is needed are described.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 34 Seiten , Illustrationen
    Serie: CRREL Report 83-16
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Conversion of metric units Introduction Review of existing models Accumulation models Ablation models Using existing models for studying mobility Proposed snowpack model for mobility studies Model components Implementation of the model Developing input data Conclusions Literature cited
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  • 26
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/4
    In: CRREL Report, 83-4
    Beschreibung / Inhaltsverzeichnis: Measurements and analysis of seasonal ice growth and decay on Post Pond, New Hampshire, for the period 1973-1982 are presented. Observations included ice thickness measurements, examination of the various ice types contributing to the ice cover, and measurements of meteorological parameters for correlation with and modeling of the ice growth process. The overall nature of ice growth and decay (ice loss) on the Post Pond has been ascertained, the seasonal variability in the timing of freeze-up and ice-out and the duration of the ice cover have been determined, and the relationship of ice growth to freezing-degree-day (deg C) records evaluated on the basis of a Stefan conduction equation modified to deal with ice sheets covered with or free of snow. Ice growth occurs predominantly by the direct freezing of lake water, but snow ice may compose as much as 50% of the ice cover in winters with higher than average snowfall. Freeze-up leading to the establishment of a stable ice cover occurs during the 4-week period from the end of November to the end of December. Maximum seasonal ice thicknesses were from 45 to 67 cm and are generally attained during the first two weeks of March; ice-out, marking the final disappearance of ice from Post Pond, usually occurs by the third week of April. The overall rate of the ice loss is three to four times that of ice growth, and is dominated initially by melting from the top. As much as 50% of the ice may be lost in this way before the onset of any bottom melting. Final dissipation of the ice cover is usually expedited by candling resulting from preferential melting and disintegration of the ice at crystal boundaries.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 30 Seiten , Illustrationen
    Serie: CRREL Report 83-4
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Location of study Study methods Ice thickness Ice-cover composition Surface air temperatures Freeze-up and ice-out characteristics Results and discussion Ice-growth record Freezing-degree-day records Ice-growth predictions Summary and conclusions Literature cited Appendix A: Ice-growth records Appendix B: Measured and computed ice-growth curves
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  • 27
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/1
    In: CRREL Report, 83-1
    Beschreibung / Inhaltsverzeichnis: Roof snow load case studies gathered throughout the United States over a three-year period are analyzed. The objective of the analysis is to determine a relationship between the snow load on the ground and the corresponding uniform snow load on flat and sloped roofs. The main parameters considered are the thermal characteristics of the roof, the roof slope and the exposure of the structure. Exposure has the strongest effect on the ratio of ground to roof snow loads. Comparisons are made with existing and proposed building codes and standards.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 47 Seiten , Illustrationen
    Serie: CRREL Report 83-1
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Metric conversion table Introduction Data base Conversion factor Ground load effects Exposure effects Thermal effects Slope effects Expected value relationship Comparison with existing codes and standards Comparison with relationships proposed in new ANSI standard Summary and conclusions Literature cited Appendix A. Roof snow load case history reports Appendix B. Roofs in the snow load case study data base Appendix C. Ground and roof snow load data Appendix D. Conversion factors from the 1982 ANSI standard
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  • 28
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/7
    In: CRREL Report, 83-7
    Beschreibung / Inhaltsverzeichnis: Peak power generation with hydropower creates tailwater flow conditions characterized by high and low flows with abrupt transitions between these states. Flows occurring in tailwaters typically form sharp-fronted, large-amplitude waves of relatively short period. An understanding of the mechanics of downstream propagation of these waves is important both for direct application in studies of the tailwater and because of the similarity of these waves to those following a dam break. An analysis of the dynamic equations of open channel flow is used to quantify the relative importance of flow wave convection, diffusion and dispersion in rivers. The relative importance of each process is re­lated to the relative magnitude of terms in the dynamic equations, providing a physical basis for model formulation. A one-dimensional diffusion wave flow routing model, modified for tailwaters, simulates the important physical pro­cesses affecting the flow and is straightforward to apply. The model is based upon a numerical solution of the kine­matic wave equation. The “modified equation,” Hirt, and von Neumann analyses are used to gain insight into the stability and dissipative and dispersive behavior of the numerical solution, and results of these analyses are compared. A set of linear routings is used to demonstrate the dissipative and dispersive behavior predicted by the analyses and to verify the accuracy of an expression that quantifies the numerical diffusion of the model. The analyses provide a basis for selection of numerical parameters for model applications. The capability and accuracy of the model are enhanced when physical wave diffusion is balanced by numerical diffusion in the model. Maintaining the diffusion balance re­quires that the time derivative weighting parameter 0 be variable and in some instances negative. Though some amount of phase error is introduced, negative 0 values have no adverse effect upon model stability. Field studies were con­ducted to demonstrate the benefits of careful model development and analysis, and to verify the diffusion wave model for rapidly varying tailwater flow. The bed slope and roughness characteristics of the field study reaches (below Apalachia and Norris Dams) differ greatly, spanning those of a large number of rivers of practical interest. The accurate simulation of flow in both of these tailwaters attests to the soundness of both the physical basis of the model and the numerical solution technique. The field studies confirm, for the extreme case of rapidly varying flow in a mildly sloped river, that inertia has a negligible effect upon unsteady flow waves at low Froude numbers. Additionally, these studies verify that diffusion of short-period waves in rivers is generally significant.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 41 Seiten , Illustrationen
    Serie: CRREL Report 83-7
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Physical diffusion and dispersion in open channel flow Modeling approach Description of the diffusion wave flow routing model Analysis of the numerical model Modified equation and Hirt analyses of diffusion wave model von Neumann analysis of the diffusion wave model Linear case studies Accuracy considerations of the numerical solution Field studies Apalachia Dam tailwater Norris Dam tailwater Conclusions Literature cited
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  • 29
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/5
    In: CRREL Report, 83-5
    Beschreibung / Inhaltsverzeichnis: This report presents the results of dynamic ice-structure interaction model tests conducted at the CRREL Ice Engineering Facility. A flexible, single-pile, bottom-founded offshore structure was simulated by a test pile with about a one-to-ten scale ratio. Urea (instead of sodium chloride) was used as dopant to scale down the ice properties, resulting in good model ice properties. Six ice fields were frozen and 18 tests carried out. In all cases distinctive dynamic ice structure interaction vibrations appeared, from which abundant data were collected. In tests with linear ice velocity sweep, sawtooth-shaped ice force fluctuations occurred first. With increasing velocity the natural modes of the test pile were excited, and shifts from one mode to another occurred. The maximum ice force values appeared mostly with low loading rates, but high forces appeared random'y at high ice velocities. As a general trend, ice force maximums, averages and standard deviations decreased with increasing ice velocities. The aspect ratio effect of the ice force in continuous crushing follows the same dependence as in static loadings. The frequency of observed ice forces is strongly dominated by the natural modes of the structure. Dynamically unstable natural modes tend to make the developing ice force frequencies the same as the natural frequencies. Otherwise the resulting frequency depends directly on structural stiffness and ice velocity and inversely on the ice force range. During vibrations the displacement rates of the structure overcome the velocity of ice, making low loading rates and hence high ice forces possible. During crushing, ice induces both positive and negative damping.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 53 Seiten , Illustrationen
    Serie: CRREL Report 83-5
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Test arrangements Ice properties Crushing patterns Maximum ice force vs velocity Dynamic aspect ratio effect and crushing strength Measured ice force frequencies Calculated ice force frequencies Accelerations, velocities and displacements Damping Ice-induced negative damping Limit cycles Buckling load Conclusions Literature cited
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  • 30
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/30
    In: CRREL Report, 83-30
    Beschreibung / Inhaltsverzeichnis: Ice sheets are formed and retained in several ways in nature, and an understanding of these factors is needed before most structures can be successfully applied. Many ice sheet retention structures float and are somewhat flexible; others are fixed and rigid or semirigid. An example of the former is the Lake Erie ice boom and of the latter, the Montreal ice control structure. Ice sheet retention technology is changing. The use of timber cribs is gradually but not totally giving way to sheet steel pilings and concrete cells. New structures and applications are being tried but with caution. Ice-hydraulic analyses are helpful in predicting the effects of structures and channel modifications on ice cover formation and retention. Often, varying the flow rate in a particular system at the proper time will make the difference between whether a structure will or will not retain ice. The structure, however, invariably adds reliability to the sheet ice retention process.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 39 Seiten , Illustrationen , 1 Beilage
    Serie: CRREL Report 83-30
    Sprache: Englisch
    Anmerkung: Contents Abstract Preface Introduction Natural ice sheets Choosing an ice control structure Flexible structures Ice booms Frazil collector lines Fence booms Rigid or semirigid structures Pier-mounted booms Stone groins Artificial islands Removable gravity structures Timber cribs Weirs Pilings and dolphins Structures built for other purposes Hydroelectric dams Wicket dams Light piers and towers Bridge piers Breakwaters Ice control not using Structures Channel improvements Ice sheet tying Ice sheet bridges Conclusions Literature cited Appendix A: Ice control structure
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  • 31
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    Signatur: ZSP-201-83/29
    In: CRREL Report, 83-29
    Beschreibung / Inhaltsverzeichnis: A literature review indicated that the effects or permafrost on streambank erodibility and stability are not yet understood because systematic and quantitative measurements are seriously lacking. Consequently, general controversy exists as to whether perennially frozen ground inhibits lateral erosion and bankline recession, or whether it increases bank recession rates. Perennially frozen streambanks erode because of modification of the bank's thermal regime by exposure to air and water, and because of various erosional processes. Factors that determine rates and locations of erosion include physical, thermal and structural properties of bank sediments, stream hydraulics and climate. Thermal and physical modification of streambanks may also induce accelerated erosion within permafrost terrain removed from the immediate river environment. Bankline or bluffline recession rates are highly variable, ranging from less than 1 m/year to over 30 m/year and, exceptionally, to over 60 m/year. Long-term observations of the physical and thermal erosion processes and systematic ground surveys and measurements of bankline-bluffline recession rates are needed.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 26 Seiten , Illustrationen
    Serie: CRREL Report 83-29
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Stream bank erosional processes Permafrost and related factors Permafrost and erosion General Erosional processes Bank zone processes Bluff zone processes Factors affecting perm afrost erodibility Exposure to currents and wind waves Texture and stratigraphy Ice content, distribution and type Slope aspect Coriolis force Timing and depth of thaw Water level and temperature Vegetation Ice and snow cover Groundwater Rates and timing of erosion and recession Overall effects of permafrost Recommendations for research Literature cited Appendix A : Processes of stream bank modifications
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  • 32
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    Signatur: ZSP-201-83/31
    In: CRREL Report, 83-31
    Beschreibung / Inhaltsverzeichnis: A mathematical model is described that is used to determine the maximum ice conveyance capacity of a river channel. Based upon this model, computer programs were developed that enable the ice discharge to be calculated for steady-state flow conditions. For rivers that have uniform flow, the maximum ice-conveying capacity can be described with a simple function expressed in terms of the size of the ice fragments, channel geometry, and the flow of water in the river. For nonuniform flows, the computer program determines the elevation profile of the surface layer in addition to other flow characteristics, such as the velocity and surface concentration of the ice fragments. The location along this surface profile where the ice conveyance capacity becomes less than the upstream supply is determined and is considered to be the position where a surface ice jam or ice bridge will be formed.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 21 Seiten , Illustrationen
    Serie: CRREL Report 83-31
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Constitutive relationships Equations of motion Uniform flow Nonuniform flow Ice transport: Uniform flow Symmetric channel Asymmetric channel Ice transport: Nonuniform flow Further considerations Basis for model improvement Conclusions Literature cited
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  • 33
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/32
    In: CRREL Report, 83-32
    Beschreibung / Inhaltsverzeichnis: Ice forces on a bridge pier in the Ottauquechee River, in Quechee, Vermont, were measured by installing fourpanels-each capable of measuring forces in the normal and tangential direction - on both sides of a vertical V-shaped pier nose. The measured forces are presented for a short period during an ice run. After the ice run, the thickness and sizes of the ice floes were measured and the compressive strength of the ice was determined in the laboratory from the ice samples collected along the river banks. The water level measurements made at several locations along theriver are also presented for the period of the ice run.
    Materialart: Schriftenreihen ausleihbar
    Seiten: ii, 8 Seiten , Illustrationen
    Serie: CRREL Report 83-32
    Sprache: Englisch
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  • 34
    Signatur: ZSP-201-83/21
    In: CRREL Report, 83-21
    Beschreibung / Inhaltsverzeichnis: The probability density function of the gouge depths into the sediment is represented by a simple negative exponential over four decades of gouge frequency. The exceedance probability function is, therefore, e to the -lambda d, where d is the gouge depth in meters and lambda is a constant. The value of lambda shows a general decrease with increasing water depth, from 9/m in shallow water to less than 3/m in water 30 to 35 m deep. The deepest gouge observed was 3.6 m, from a sample of 20,354 gouges that have depths greater than or equal to 0.2 m. The dominant gouge orientations are usually unimodal and reasonably clustered, with the most frequent alignments roughly parallel to the general trend to the coastline. The value of N(bar) sub 1, the mean number of gouges (deeper than 0.2 m) per kilometer measured normal to the trend of the gouges, varies from 0.2 for protected lagoons to 80 in water between 20 and 38 m deep in unprotected offshore regions. The distribution of the spacings between gouges as measured along a sampling track is a negative exponential. The form of the frequency distribution of N sub 1 varies with water depth and is exponential for lagoons and shallow offshore areas, previously skewed for 10 to 20 m depths off the barrier islands, and near-normal for deeper water. As a Poisson distribution gives a reasonable fit to the N sub 1 distributions for all water depths, it is suggested that gouging can be taken as approximating a Poisson process in both space and time. The distributions of the largest values per kilometer of gouge depths, gouge widths, and the heights of the lateral embankment of sediments plowed from the gouges are also investigated.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 40 Seiten , Illustrationen, 1 Karte
    Serie: CRREL Report 83-21
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Background and environmental setting Data collection and terminology Data analysis Gouge depths Gouge orientation Gouge frequency Extreme value analysis Applications to offshore design Gouge depth Extreme value statistics Burial depths Conclusion Literature cited Appendix A: Detailed bathymetric map of the Alaskan portion of the Beaufort Sea
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  • 35
    Signatur: ZSP-201-83/22
    In: CRREL Report, 83-22
    Beschreibung / Inhaltsverzeichnis: A new experimental method for measuring the soil-water diffusivity of frozen soil under isothermal conditions is introduced. The theoretical justification of the method is presented and the feasibility of the method is demonstrated by experiments conducted using marine-deposited clay. The measured values of the soil-water diffusivity are found comparable to reported experimental data.
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    Seiten: 13 Seiten , Illustrationen
    Serie: CRREL Report 83-22
    Sprache: Englisch
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  • 36
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/23
    In: CRREL Report, 83-23
    Beschreibung / Inhaltsverzeichnis: The problems associated with measuring stresses in ice are reviewed. Theory and laboratory test results are then presented for a stiff cylindrical sensor made of steel that is designed to measure ice stresses in a biaxial stress field. Loading tests on freshwater and saline ice blocks containing the biaxial ice stress sensor indicate that the sensor has a resolution of 20 kPa and an accuracy of better than 15% under a variety of uniaxial and biaxial loading conditions. Principal stress directions can also be determined within 5 degrees. The biaxial ice stress sensor is not significantly affected by variations in the ice elastic modulus, ice creep or differential thermal expansion between the ice and gauge. The sensor also has a low temperature sensitivity (5 kPa/deg C).
    Materialart: Schriftenreihen ausleihbar
    Seiten: 38 Seiten , Illustrationen
    Serie: CRREL Report 83-23
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Previous work Stress measurements Design considerations Stress sensors Biaxial ice stress sensor Biaxial stress sensor theory Gauge deformation Stresses associated with cylindrical sensors Determination of ice stresses Gauge calibration Evaluation of the biaxial ice stress sensor Temperature sensitivity Biaxial loading test equipment Biaxial loading test results Differential thermal expansion Long-term drift Discussion of test results Conclusions Literature cited
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  • 37
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/11
    In: CRREL Report, 83-11
    Beschreibung / Inhaltsverzeichnis: Investigations of ground radar performance over thawed and seasonally frozen silts, and sands and gravels containing artificial and natural reflectors were carried out in Alaska. The radar emitted 5-10 ns pulses, the center frequency of which was approximately 150 MHz. The artificial reflectors were metal sheets and discs and the natural reflectors were the groundwater table and interfaces between frozen and thawed material. The water table was profiled at three sites where the subsurface material was coarse-grained alluvium. Dielectric constants of 16 to 18 were measured for the thawed silts, 6 to 7 for the frozen silts and 3 to 9 for the sands and gravels. Signal penetration in the thawed high moisture content silts may be achieved only by use of a lower frequency radar, whereas in the sands and gravels greater depths may be detected with more sophisticated signal processing.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 16 Seiten , Illustrationen
    Serie: CRREL Report 83-11
    Sprache: Englisch
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  • 38
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/25
    In: CRREL Report, 83-25
    Beschreibung / Inhaltsverzeichnis: Ice action on two cylindrical and conical structures, located side by side, was investigated in a small-scale experimental study to determine the interference on the ice forces generated during ice-structure interaction. The proximity of the two structures changes the mode of ice failure, the magnitude and direction of ice forces on the individual structure, and the dominant frequency of ice force variations. Interference effects were determined by comparing the experimental results of tests at different structure spacings.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 42 Seiten , Illustrationen
    Serie: CRREL Report 83-25
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Experimental setup and procedure Results and discussion Cylindrical structures Conical structures Conclusions Literature cited Appendix A: Relationship between flexural strength and in-situ unconfined compressive strength Appendix B: Test data
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  • 39
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/17
    In: CRREL Report, 83-17
    Beschreibung / Inhaltsverzeichnis: A sea ice model was applied to the East Greenland Sea to examine a 60-day ice advance period beginning 1 October 1979. This investigation compares model results using driving geostrophic wind fields derived from three sources. Winds calculated from sea-level pressures obtained from the National Weather Service's operational analysis system resulted in strong velocities concentrated in a narrow band adjacent to the Greenland coast, with moderate velocities elsewhere. The model showed excessive ice transport and thickness build-ups in the coastal region. The extreme pressure gradient parallel to the coast resulted partially from a pressure reduction procedure that was applied to the terrain-following sigma coordinate system to obtain sea-level pressures. Additional sea-level pressure fields were obtained from an independent optimal interpolation analysis that merged FGGE buoys drifting in the Arctic basin with high latitude land stations and from manual digitization of the NWS hand-analyzed Northern Hemisphere Surface Charts. Modeling results using winds from both of these fields agreed favorably.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 19 Seiten , Illustrationen
    Serie: CRREL Report 83-17
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Description of study Model results The problem Conclusions Literature cited
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  • 40
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/26
    In: CRREL Report, 83-26
    Beschreibung / Inhaltsverzeichnis: Ice accreted on high-speed rotors operating in supercooled fog can be thrown off by centrifugal force, creating severe unbalance and dangerous projectiles. A simple force balance analysis indicates that the strength of accreted ice and its adhesive strength can be obtained by measuring the thickness of the accretion, the location of the separation, the rotor speed, and the density. Such an analysis was applied to field and laboratory observations of self-shedding events. The results agree reasonably well with other observations.
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    Seiten: 13 Seiten , Illustrationen
    Serie: CRREL Report 83-26
    Sprache: Englisch
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  • 41
    Signatur: ZSP-201-83/24
    In: CRREL Report, 83-24
    Beschreibung / Inhaltsverzeichnis: Secondary recovery of oil at Prudhoe Bay, Alaska, will involve transporting large quantities of seawater in elevated pipelines across tundra for injection into oil-bearing rock strata. The possibility of a pipeline rupture raises questions concerning the effects of seawater on tundra vegetation and soils. To evaluate the relative sensitivities of different plant communities to seawater, eight sites representing the range of vegetation types along the pipeline route were treated with single, saturating applications of seawater during the summer of 1980. Within a month of the treatment 30 of 37 taxa of shrubs and forbs in the experimental plots developed clear symptoms of stress, while none of the 14 graminoid taxa showed apparent adverse affects. Live vascular plant cover was thus reduced by 89 and 91% in the two dry sites and by 54, 74 and 83% in the three moist sites, respectively. Live(green) bryophyte cover was markedly reduced in the moist experimental sites in 1981. Bryophytes in all but one of the wet-site experimental plots were apparently unaffected by the seawater treatment. Two species of foliose lichens treated with seawater showed marked deterioration in 1981. All other lichen taxa were apparently unaffected by the seawater treatment. The absorption and retention of salts by the soil is inversely related to the soil moisture regime. In the wet sites, conductivities approached prespill levels within about 30 days. In such sites, spills at the experimental volumes are quickly diluted and the salts flushed from the soil. In the dry sites, on the other hand, salts are retained in the soil, apparently concentrating at or near the seasonal thaw line.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 43 Seiten , Illustrationen
    Serie: CRREL Report 83-24
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Methods Site selection and preparation Prespill assessment Seawater application Postspill assessment Enzyme assay and analysis of soil flora Results and discussion Soil-solution conductivities Vascular plant response Cryptogam response Site factors and plant response Soil flora and extracellular soil enzymes Limitations of this study Summary and conclusions Literature cited Appendix: Plant taxa included in this study
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  • 42
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    Signatur: ZSP-201-83/33
    In: CRREL Report, 83-33
    Beschreibung / Inhaltsverzeichnis: A thermodynamic model has been developed that for the first time describes the entire creep process, including primary, secondary, and tertiary creep, and failure for both constant stress (CSR) tests (σ= const.) and constant strain rate (CSR) tests (ϵ = const.), in the form of a unified constitutive equation and unified failure criteria. Deformation and failure areconsidered as a single thermoactivated process in which the dominant role belongs to the change of entropy. Failure occurs when the entropy change is zero. At that moment the strain rates in CS tests reach the minima and stress in CSR tests reaches the maximum (peak) values. Families of creep (ϵ vs τ) and stress-strain (σ vs ϵ) curves, obtained from uni-axial compression CS and CSR tests of frozen soil, respectively (both presented in dimensionless coordinates), are plotted as straight lines and are superposed, confirming the unity of the deformation and failure process and the validity of the model. A method is developed for determining the parameters of the model, so that creep deformation and the stress-strain relationship of ductile materials such as soils can be predicted based upon information obtained from either type of test.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 25 Seiten , Illustrationen
    Serie: CRREL Report 83-33
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Nomenclature Introduction Principal relationships Constitutive equation Failure criteria Secondary creep: Flow equations Creep at constant stress (σ = Const.) Creep model Creep strain (σ = Const.) Creep at constant strain rate (ϵ = Const.) Stress-strain relationship Stress/strain/strain rate at failure Test data Preliminary analysis Constant stress tests (σ = Const.) Constant strain rate tests (ϵ = Const.) The principle of superposition Thermodynamic equation of creep Conclusions Literature cited
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  • 43
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/2
    In: CRREL Report, 77-2
    Beschreibung / Inhaltsverzeichnis: A computer program was developed for finding the d-c resistance to ground of two simple electrodes, a straight horizontal wire and a vertically driven rod. The objective of this study was to develop a rapid means of finding the resistance to ground of simple electrode types in arctic environments where a two-layer earth model, frozen and unfrozen ground, is applicable. The program can consider homogeneous as well as two-layer earth, and the length, diameter and position of the electrodes. The computations were performed first by dividing an electrode into several smaller segments. Next the electrostatic potential of each segment was computed at the center of the electrode for unit-applied current. The segment potentials were then summed to find the total resistance to ground. Some specific computations are presented in comparison with previous theoretical work of other authors. The following conclusions were made: 1) A maximum run time of 165 seconds is needed for all two-layer arctic models where (a) the depth of the upper layer does not exceed 10 m, (b) the vertical rod length is less than 30 m, or (c) the horizontal wire length is less than 100 m; 2) Best accuracy is obtained when rod and wire radii are less than 0.01 m; and 3) Coincidence of the center of the vertical electrode with the two-layer interface must be avoided.
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    Seiten: iv, 16 Seiten , Illustrationen
    Serie: CRREL Report 77-2
    Sprache: Englisch
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  • 44
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/3
    In: CRREL Report, 77-3
    Beschreibung / Inhaltsverzeichnis: Tests were conducted in uniaxial compression and tension to determine the effect of temperature on the strength of frozen Fairbanks silt. Test temperatures ranged from 0 C to -56.7 C. Two machine speeds, 4.23 cm/sec and 0.0423 cm/sec, were used for the constant displacement rate tests. From the highest to the lowest temperature, the compressive strength increased up to about one order of magnitude and the tensile strength increased one-half an order of magnitude. Equations are presented which correlate strength with temperature at the strain rates obtained. The initial tangent and 50% strength moduli and the specific energy are given for each test. The mode of fracture and the effects of unfrozen water content and ice matrix strengthening are discussed, and the test results are compared with the data of other investigations.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 27 Seiten , Illustrationen
    Serie: CRREL Report 77-3
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Sample preparation Apparatus and testing procedure Test results Discussion Compressive strength Tensile strength Initial tangent and 50% stress moduli Specific energy Mode of failure Strength as a function of unfrozen water Thermal activation Conclusions and recommendations Literature cited
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  • 45
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/6
    In: CRREL Report, 77-6
    Beschreibung / Inhaltsverzeichnis: It has been reported that small arms projectiles are inherently unstable in snow and that snow has an unexpectedly high ability to stop them and other fast-moving projectiles. Field tests showed that the typical subarctic snow of interior Alaska can be used effectively to provide protection from both rifle and machine gun fire. The undisturbed snow had an average density of 0.18 g/cu. cm., but simple processing, such as shoveling, increased the density to around 0.34 g/cu. cm. Further processing increased the density to above o.40 g/cm3 but densities much above that value were difficult to obtain with simple hand equipment. Tests of the M16 rifle and M60 and M2HB machine guns showed that bullet penetration was inversely related to density - the higher the density the lower the bullet penetration. Design values for the three weapons were determined. A number of types of snow trenches and structures were designed and tested. They were found to provide good protection, in part since bullets showed a strong tendency to ricochet from the snow surface when striking it at a low angle. Burlap bags were filled with snow to revet structures and worked very well. Several types of Russian defensive works of snow were tested but proved unsuitable in the light, weak subarctic snow. The times required for troops to build several types of structures using only shovels and scoops were recorded.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 23 Seiten , Illustrationen
    Serie: CRREL Report 77-6
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Summary Background Objectives Subarctic snow General Snow processing Construction productivity Shovel capacity Snow piles Bullet behavior and penetration in snow Test procedure M16 M60 ball M60 tracers .50 caliber Tumbling Bullet deformation and breakage Design penetration values Defensive works of snow Revetments Snow bags The snow trench The hardened snow trench Breastworks and bunkers Evaluation of foreign technology Russian expedient snow trenches Snow blocks and block structures The snow arch An expedient shelter Conclusions Recommendations Literature cited
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  • 46
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    Signatur: ZSP-201-77/1
    In: CRREL Report, 77-1
    Beschreibung / Inhaltsverzeichnis: Studies of the growth history and structural characteristics of winter ice covers on two New Hampshire lakes are described. These investigations included measurements of ice cover thickness, characterization of the stratigraphic and crystalline structure of the ice, identification and classification of major ice types and measurements of electrolytic conductivity. The formation of cracks and flaws in the ice and their effects on the mechanical properties of the ice were also investigated. A method of correlating ice growth with surface wind and temperature measurement is described and the interrelationships of the various physical and mechanical properties of temperate lake ice covers are discussed.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 29 Seiten , Illustrationen
    Serie: CRREL Report 77-1
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Summary Introduction Study areas Study methods Winter freeze-up Composition of ice cover Freezing degree day records and applications Evaluation of ice growth coefficient α Growth history and entrapped bubble stratigraphy Mechanical properties Electrolytic conductivity Literature cited
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  • 47
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-77/4
    In: CRREL Report, 77-4
    Beschreibung / Inhaltsverzeichnis: The ice booms on the St. Marys River at Sault Ste.Marie, Michigan and Ontario, were operated a second winter, 1976-77, under colder conditions, with less water flow, lower water levels, and 25% fewer ships in the river than during the previous year. The ice cover behind the booms remained frozen to shore for longer periods, and the loads registered in the booms were relatively unaffected by ship passages compared with the previous year's activity. As in the previous year, most structural load changes took place in the west ice boom and were due to movements of the ice cover immediately upstream of the boom. The cover broke free from shore on three occasions: the first and third occasions were minor events, but on the second occasion the cover cracked free, the timbers remained frozen to it, and the boom structure became damaged by the subsequent ice activity. Three anchor line assemblies broke over a period of about 4 hours; the two latter breaks occurred while a ship was operating in the ice. The first break was in an instrumented line and the measured load was unexpectedly low. The most important break was in the main shore anchor and this opened the boom. The maximum force at this anchor was estimated as less than 115 tons (1,023 kN). Some ice moved downstream without serious consequence and the boom was reconnected in two days. These events point out several factors to be considered in ice booms, such as designing the booms to withstand the action of the solid ice cover as well as the fragmented ice cover, keeping the structures and their assembly simple, and inspecting components and assemblies carefully.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 26 Seiten , Illustrationen
    Serie: CRREL Report 77-4
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Summary Introduction Ice boom basic principles General loading considerations Design ice areas Prediction of ice boom loads Summary Ice cover forces Ice barrier reaction force Ice forces in the structure Analytical relationships Design force summary Special features Extension of west ice boom Pipe restraint structure Diagonal anchor cables Measurement systems Measured anchor cable forces Data records Average and peak loads Ice activity on or about 1 February 1976 C3W cable forces Ship-induced leads Ice cover load check Conclusions Recommendations Literature cited Appendix A. St. Marys River ice booms test data
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  • 48
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/18
    In: CRREL Report, 83-18
    Beschreibung / Inhaltsverzeichnis: An evaluation of an impulse radar system for detecting cavities under concrete pavement is discussed, and field results are presented. It was found that a dual antenna mode of surveying was ideal for void detection. In this mode one antenna operated in a transceive mode and a second, offset from the first, operated in a receive-only mode. This arrangement allowed a refraction-type profile survey to be performed, which enabled subpavement voids to be easily detected. Field trails were held at Plattsburgh Air Force Base, where 28 cavities were detected and mapped. Drilling of holes verified that a cavity existed and allowed cavity depth to be measured. The cavities varied from 1.5 in. to 23 in, depth and were up to 20 ft. long.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 49 Seiten , Illustrationen
    Serie: CRREL Report 83-18
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Plattsburgh Air Force Base Radar sounding system Survey procedure Cavity inspection Radar cavity detection test Radar profile results Falling-weight deflectometer tests Discussion and conclusions Literature cited
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  • 49
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/12
    In: CRREL Report, 83-12
    Beschreibung / Inhaltsverzeichnis: This paper documents the development and verification of two finite difference models that solve the general two-dimensional form of the heat conduction equation, using the alternative-direction implicit method. Both can handle convective, constant flux, specified temperature and semi-infinite boundaries. The conducting medium may be composed of many materials. The first program, ADI, solves for the case where no change of state occurs. ADIPC solves for case where a freeze/thaw change of phase may occur, using the apparent heat capacity method. Both models are verified by comparison to analytical results.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 74 Seiten , Illustrationen
    Serie: CRREL Report 83-12
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Finite differences applied to heat transfer Heat conduction equation Boundary conditions Phase change Computer program ADDATA, the data subroutine TRIDIG, the matrix solver ISOTHM, the isotherm finider ADI, main program ADEPC, main program Verification of ADI Comparison of ADI with analytical results Comparison of ADI with experimental results Verification of ADIPC Comparison of ADIPC with analytical results-the Neumann solution Comparison of ADIPC with analytical results-two-dimensional phase change verification User instruction for ADI User instruction for ADIPC Conclusions Literature cited Appendix A. Program INFSUM and sample input and output for program ADI Appendix B. Program ADIPC and sample input and output
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  • 50
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/9
    In: CRREL Report, 83-9
    Beschreibung / Inhaltsverzeichnis: Recent observations of shore ice pile-up and ride-up along the coast of the Alaska Beaufort Sea are presented. Information is given to show that sea ice movement on shore has overridden steep coastal bluffs and has thrust inland over 150 m, gouging into and pushing up mounds of beach sand, gravel, boulders and peat and, inland, the tundra material. The resulting ice scar morphology was found to remain for tens of years. Onshore ice movements up to 20 m are relatively common, but those over 100 m are very infrequent. Spring is a dangerous time, when sea ice melts away from the shore, allowing ice to move freely. Under this condition, driving stresses of less than 100 kPa can push thick sea ice onto the land.
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    Seiten: v, 59 Seiten , Illustrationen
    Serie: CRREL Report 83-9
    Sprache: Englisch
    Anmerkung: Contents Abstract Preface Introduction Winter 1979-80 observations Winter 1980-81 and summer 1981 observations Winter 1981-82 and summer 1982 observations Old ice ride-up features Discussion Literature cited Appendix A. The boulder rampart and rock littered shore west of Konganevik Pt. Appendix B. Site location maps
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  • 51
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/8
    In: CRREL Report, 83-8
    Beschreibung / Inhaltsverzeichnis: In the course of model tests with urea-doped ice in the CRREL Ice Engineering Facility test basin, the growth process and the physical and mechanical properties of the model ice were investigated. The parameters which were varied were: urea concentration in the tank water, air temperature during growth, growth duration, and tempering time. Uniformity of ice thickness and ice mechanical properties over the whole tank area were found to be satisfactory. The structure of the urea-doped ice was found to be similar to that of the ice except for a relatively thick incubation layer over a dendritic bottom layer. Empirical relationships were established between: ice thickness and negative degree-hours; mechanical properties and growth temperature, urea concentration, and ice thickness; and reduction in mechanical properties and tempting time. The results of the study are presented in charts which permit reliable scheduling of model tests with required ice thickness and ice flexural strength.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vii, 53 Seiten , Illustrationen
    Serie: CRREL Report 83-8
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Experimental facility and procedures Ice test basin Ice growth procedure Measurements Ice growth and structure Ice thickness distribution Ice growth during freeze-up Ice growth during warm-up Structure of urea-doped ice Mechanical properties of urea-doped ice Introductory remarks Model of a two-layer elastic material Properties of urea-doped ice during freeze-up Properties of urea-doped ice during warm-up Applications to test program scheduling Summary and conclusions Literature cited Appendix A: Results of ice thickness measurements for various growth conditions Appendix B: Properties of untempered ice Appendix C: Properties of tempered ice
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 52
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-83/6
    In: CRREL Report, 83-6
    Beschreibung / Inhaltsverzeichnis: During the austral summers of 1976-77 and 1978-79, several ice cores were taken from the McMurdo Ice Shelf brine zone to investigate its thermal, physical and chemical properties. This brine zone consists of a series of super-imposed brine layers (waves) that originate at the seaward edge of the ice shelf and migrate at various rates, depending upon their age and position in the ice shelf. The brine in these layers becomes increasingly concentrated as the waves migrate inland through the permeable ice shelf firn. Chemical analyses of brine samples from the youngest (uppermost) brine wave show that it contains sea salts in normal seawater proportions. Further inland, deeper and older brine layers, though highly saline (S 〉 200 ‰), are severely depleted in SO2-4 with the SO2-4/Na+ ratio being an order of magnitude less than that of normal seawater. Analyses of Na+, K+, Ca2+, Mg2+, SO2-4 and CI-, together with solubility and temperature considerations, show that the sulfate depletion is due to selective precipitation of mirabilite, Na2SO4*10H2O. The location of the inland boundary of brine penetration is closely related to the depth at which the brine en-counters the firn/ice transition. However, a small but measurable migration of brine is still occurring in otherwise impermeable ice; this is attributed to eutectic dissolution of the ice by concentrated brine as it moves into deeper and warmer parts of the McMurdo Ice Shelf.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 16 Seiten , Illustrationen
    Serie: CRREL Report 83-6
    Sprache: Englisch
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 53
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-83/2
    In: CRREL Report, 83-2
    Beschreibung / Inhaltsverzeichnis: A numerical model of rime ice accretion on an arbitrary two-dimensional airfoil is presented. The physics of the model are described and results are presented that demonstrate, by comparison with other theoretical data and experimental data, that the model predictions are believable. Results are also presented that illustrate the capability of the model to handle time-dependent rime ice accretion, taking into account the feedback between the ice accretion and the airflow and droplet trajectory fields.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 81 Seiten , Illustrationen
    Serie: CRREL Report 83-2
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Methodology Potential flow around an arbitrary airfoil Incompressible velocity field Droplet trajectory equation Computational procedure for trajectories Determining the point of impact Calculation of collision efficiencies Accreting an ice layer Determining the accuracy of the flow field Determining the accuracy of the trajectories Results and discussion Comparing results with and without the history term Collision efficiency of NACA 0015 airfoil at 8° attack angle Time-dependent accretion on NACA 0015 airfoil at 8° attack angle Time-dependent accretion on NACA 0015 airfoil at 0° attack angle Conclusions and recommendations Literature cited Appendix A : Sample input Appendix B: Sample output Appendix C : Program listing
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-83/19
    In: CRREL Report, 83-19
    Beschreibung / Inhaltsverzeichnis: Small-scale laboratory experiments were conducted on model bridge piers in the CRREL test basin. The experiments were performed by pushing model ice sheets against structures and monitoring the ice forces during the ice/structure interaction. The parameters, varied during the test program, were the geometry of the bridge piers and the velocity, thickness, and flexural strength of the ice. The results are presented in the form of ice forces on sloping and vertical structures with different geometries. During ice action on sloping structures, a phenomenon of transition of failure mode from bending to crushing was observed as the ice velocity was steadily increased.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 17 Seiten , Illustrationen
    Serie: CRREL Report 83-19
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Tests Results Ice forces on inclined structures Transition of ice action due to velocity increase Aspect ratio Bridge pier nose geometry Conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
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