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Hanover, NH : Corps of Engineers, U.S. Army Cold Regions Research and Engineering Laboratory
Call number: ZSP-202-342
In: Research report / Cold Regions Research and Engineering Laboratory
Description / Table of Contents: CONTENTS: Abstract. - Preface. - Introduction. - Experimental procedure. - Results. - Work-hardening effect. - Strain rate sensitivity of flow stress. - Discussion. - Conclusions. - Literature cited.
Description / Table of Contents: Single crystals of high purity ice deformed by uniaxial compression on an Instron machine showed remarkable work-hardening after about 8% strain. By changing the strain rate during compression tests in the plastic region of the stress-strain curve, an apparent activation volume V* and a dislocation mobility exponent m were calculated from the strain rate sensitivity of flow stress. The large work-hardening and the rapid increase in the value of m beyond about 10% strain indicate that the plastic flow in this region is controlled by dislocation intersections and nonconservative motion of jogs.
Type of Medium: Series available for loan
Pages: iii, 11 Seiten , Illustrationen
Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 342
Language: English
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  • 2
    Series available for loan
    Series available for loan
    Hanover, NH : Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command
    Call number: ZSP-202-325
    In: Research report
    Description / Table of Contents: CONTENTS: Preface. - Symbols. - Introduction. - Physical properties of ice, water and snow. - Electrical relations affecting the problem. - The dielectric constant. - Deloor's theory. - Wet snow application. - Experimental procedure. - Measurement technique. - Sample preparation. - Glass bead preparation. - Experimental results. - Wet snow results. - Glass bead results. - Experimental error. - Discussion. - Conclusions. - Recommendations. - Literature cited. - Selected bibliography. - Appendix A. The measurement of the complex dielectric constant in a shorted wave guide. - Appendix B. Evaluation of the effective particle shape factor and the effective dielectric properties in the immediate vicinity of average liquid and solid particles. - Appendix C. Experimental data. - Abstract.
    Description / Table of Contents: An accurate method of measuring liquid water in snow covers is required to determine the properties of wet snow. The dielectric properties of wet snow must be utilized to adequately measure its liquid water content. In this study the effect of liquid water on the complex dielectric constant of natural snow is determined in the microwave frequency range. Deloor's method for calculating the dielectric constant for mixtures and the results of waveguide experiments on samples of wet snow and glass beads are used to construct a calibration curve relating the measured dielectric loss factor directly to the water content of wet snow. The results are independent of porosity, past history and chemical impurities. A relation between the effective dielectric constant and the porosity and water content is proposed and tested, experimentally. The general nature of this relation is described and suggestions are made for the development of a more precise relation. It is concluded that the dielectric constant is a function of porosity and water content only.
    Type of Medium: Series available for loan
    Pages: vi, 33 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 325
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  • 3
    Call number: ZSP-202-347
    In: Research report / Cold Regions Research and Engineering Laboratory, 347
    Description / Table of Contents: CONTENTS: Abstract. - Preface. - Introduction. - Experimental. - Results and discussion. - Applications. - Literature cited.
    Description / Table of Contents: Chemical analysis of century-old ice from continuous 5 to 7 year intervals of three ice cores from south and central Greenland (Dye 3, Milcent and Crete) show maximum concentrations of Na, Mg,Ca, K, and Al during early spring and minimum concentrations during late summer and early fall. Peak spring values are as much as 10 times greater than fall values. Because of the large seasonal chemical variations, samples used for depth-age or annual deposition rate studies must represent accumulation from exactly one year or whole multiples of a year. The seasonal chemical variations seem promising as a new method of defining annual layers and thus dating old ice cores.
    Type of Medium: Series available for loan
    Pages: iii, 5 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 347
    Language: English
    Location: AWI Archive
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  • 4
    Call number: ZSP-202-344
    In: Research report
    Description / Table of Contents: CONTENTS: Abstract. - Preface. - Introduction. - Approach and methods. - Results. - Lake morphology. - Elongation. - Orientation. - Percentage cover (density). - Lake classification. - L1 unit. - L2 unit. - L3 unit. - L4 unit. - L5 and Lu units. - Other units. - Lake basin depths. - Ice volume and basin genesis. - Geological implications. - Conclusions. - Selected bibliography.
    Description / Table of Contents: The lakes of the Arctic Coastal Plain of northern Alaska were classified, based on size, shape, orientation and distribution, into six lake units and three nonlake units. Regional slope and relief were demonstrated to control lake size, the largest lakes occurring on the flattest, northernmost segment of the Coastal Plain. Using ERTS-1 sequential imagery and existing photography and data, lakes were grouped according to three depth ranges, 〈 1 m, 1-2 m and 〉 2 m. Deepest lakes have the longest period of summer ice cover. Ice on shallow lakes melts the earliest. Maximum depths of lakes were computed based on ice volume content of the perennially frozen ground (permafrost) and these agreed with observed values and ranges. The lake classification and regional ERTS-1 coverage also appear to provide additional information on the limits of late-Pleistocene transgressions on the Coastal Plain.
    Type of Medium: Series available for loan
    Pages: iv, 21 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 344
    Language: English
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  • 5
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    Series available for loan
    Hanover, NH : Corps of Engineers, U.S. Army Cold Regions Research and Engineering Laboratory
    Call number: ZSP-202-341
    In: Research report
    Description / Table of Contents: CONTENTS: Abstract. - Preface. - Introduction. - Samples. - Collection. - Preparation. - Analytical methods. - Cations. - Lead, silicon and aluminum. - Sulfate. - Comparative analyses. - Results and discussion. - Sea salt and terrestrial dust. - Sulfate. - Lead. - Summary and conclusions. - Literature cited. - Appendix A. Concentrations of chemical constituents in Dye 3 snow and ice strata.
    Description / Table of Contents: Concentrations of sodium, potassium, magnesium, calcium, silicon, aluminum, lead and sulfate were measured in surface snow and in individual annual accumulation layers from a 373-m-deep ice core from Dye 3, Greenland, covering the time period from 1232 to 1971 A.D. Average background (pre-1840) concentrations in micrograms/liter are: Na, 12.9 ± 9.3; K, 2.2 ± 2.1; Mg, 1.5 ± 1.0; Ca, 4.8 ± 2.4; Si, 12 ± 6; Al, 3.3 ± 1.4; Pb, 0.07 ± 0.06; and SO4, 56 ± 22. Deviations are due mainly to the variability of the concentrations in the samples deposited over the stated time interval rather than analytical precision. Observed concentrations of sodium, potassium, magnesium, calcium, silicon and aluminum can be adequately explained by relative abundances of these elements in seawater andterrestrial dust. Late 19th century annual ice layers contain twice as much sulfate as pre-1840 deposits, reflecting the increased use of fossil fuels in the Northern Hemisphere. Lead concentrations in post-1955 snow deposits are more than an order of magnitude greater than pre-1840 baseline concentrations and are attributed to smelting and the increased use of lead alkyls in gasoline.
    Type of Medium: Series available for loan
    Pages: v, 18 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 341
    Language: English
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  • 6
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    Series available for loan
    Hanover, NH : Corps of Engineers, U.S. Army, Cold Regions Research and Engineering Laboratory
    Call number: ZSP-202-333
    In: Research report
    Description / Table of Contents: CONTENTS: Preface. - Introduction. - Analogy method. - Method based on the bending theory of elastic plates and the criterion [Sigma]max = [Sigma]f. - Methods based on viscoelastic theories. - Methods based on the yield line theory or limit analysis. - Comparison of analytical and test results. - General remarks. - Effect of bending and shearing forces on deflection of an ice cover. - Determination of Pf(O). - Determination of Pf(t). - Determination of [Sigma]f. - Summary and recommendations. - Literature cited.
    Description / Table of Contents: This report contains a critical survey of the literature on the bearing capacity of floating ice plates. It consists of a discussion of general questions, a critical survey of analytical attempts to determine the bearing capacity of floating ice plates, and a survey of field and laboratory tests on floating ice plates and their relation to the analytical results. The paper concludes with a systematic summary of the results, a discussion of observed shortcomings, and suggestions for needed investigations.
    Type of Medium: Series available for loan
    Pages: iv, 43 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 333
    Language: English
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  • 7
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    Series available for loan
    Hanover, NH : Army Cold Regions Research and Engineering Laboratory
    Call number: ZSP-202-330
    In: Research report
    Description / Table of Contents: Studies were completed in several black spruce and aspen/birch communities of the Caribou Creek Watershed. Frequency and basal area or percent cover are detailed for tree, sapling, shrub, herbaceous, moss, and lichen species. Organic layer mass was greatest beneath a north slope black spruce community. Carbon and nitrogen levels were higher in litter layers beneath the hardwood stands, whereas carbon/nitrogen ratios were higher in the living and decaying organic mat beneath black spruce. Concentrations of P, Ca, Mg, Mn and Zn were higher in hardwood than in conifer organic layers. K and Fe concentrations in organic layers were similar beneath hardwoods and conifers. Soils beneath conifer and hardwood stands could not be separated on the basis of pH, %C, %N or C/N ratios. Cation exchange capacity closely reflected %C in all soils. More exchangeable bases were present in soils beneath hardwood communities than beneath black spruce communities. Increases in extractable P were found near the soil surface in aspen-dominated communities. Extractable soil P increased below 15 cm in conifer stands.
    Type of Medium: Series available for loan
    Pages: iii, 25 S. : Ill., graph. Darst.
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 330
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  • 8
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    Series available for loan
    Hanover, NH : Corps of Engineers, U.S. Army, Cold Regions Research and Engineering Laboratory
    Call number: ZSP-202-282
    In: Research report
    Description / Table of Contents: CONTENTS: Introduction. - Analytical procedures. - Measurement of crystal size. - Measurement of crystalorientation. - Results and discussion. - Byrd Station crystal structure and fabrics. - Little America V crystal structure and fabrics. - Conclusions. - Literature cited. - Abstract.
    Description / Table of Contents: Radical differences in the crystal structure and fabrics of glacier ice cores at Byrd Station and Little America V, Antarctica, are attributed to gross differences in the thermal and deformational histories of the ice at these two locations. At Byrd Station the mean size of crystals increased more than sixfold between 65 m and the bottom of the drill hole at 309 m. Crystal size was also found to increase linearly with the age of the ice, thus simulating isothermal grain growth in metals. However, this growth was not accompanied by any dimensional orientation of crystals or entrapped bubbles, or by any significant increase in the degree of preferred orientation of crystallographic c-axes. These observations imply that negligible shearing is occurring in the top 300 m of the thick grounded ice sheet at Byrd Station. By contrast very considerable deformation is indicated for the floating 258-m-thick Ross Ice Shelf at Little America. This deformation is characterized by the widespread occurrence of "strained" crystals below 65 m, the existence of elongated oriented bubbles between 95 m and 130 m and the attainment of pronounced crystal orientation (multiple-maxima fabrics) by 100-m depth. Exaggerated growth of crystals below 150 m is attributed to increasing temperatures in the ice shelf. The crystal structure of these cores clearly demonstrates that glacial ice only is present in the Ross Ice Shelf at Little America V.
    Type of Medium: Series available for loan
    Pages: iii, 21 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 282
    Language: English
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  • 9
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    Series available for loan
    Hanover, NH : Corps of Engineers, U.S. Army Cold Regions Research and Engineering Laboratory
    Call number: ZSP-202-243
    In: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command, 243
    Description / Table of Contents: The internal friction of single-crystal ice has been attributed to reorientation of the water molecule under periodic stress. However, the theory for damped dislocations, which offers another mechanism for the internal friction of ice, has not been investigated. The effects of scratching the surface of 41 ice samples and X-irradiating and plastically deforming them were evaluated. The effects observed on the internal friction of pure, single-crystal ice, in the flexure mode of oscillation between 400 and 1400 Hz, supported the existence of a dislocation-controlled mechanism, with the drag produced by the interaction of the dislocation with the protons in the crystal. In addition, analysis of the detailed shape of the data curve showed two peaks of tan delta as a function of temperature. The second peak, which had not been previously reported, had an activation energy of 0.16 eV and a relaxation time of 1.7 x 10^8 sec at infinite temperature. These experiments indicated that both peaks vrere controlled by the dislocation mechanism described above.
    Type of Medium: Series available for loan
    Pages: iv, 41 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 243
    Language: English
    Note: CONTENTS: Introduction. - Previous work. - Previous theory. - Internal friction of a crystal. - Granato-Lücke theory of dislocation damping. - Double kink mechanism. - Mechanisms not involving dislocations. - Experimental work. - Experimental approach. - Experimental apparatus. - Mode of oscillation. - Automated system. - Support, acoustic isolation, and temperature control. - Sample preparation. - X-ray apparatus. - Data analysis. - Stage I. - Stage II. - Stage III. - Experimental results and discussion. - The second peak. - Interpretation of scratching, X-irradiation, and plastic deformation. - Scratching. - X-irradiation. - Plastic deformation. - Supporting research. - Interpretation of the two peaks. - Conclusions. - Literature cited. - Appendix A: Computer programs. - Abstract.
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  • 10
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    Series available for loan
    Hanover, NH : U.S. Army Materiel Command, Terrestrial Sciences Center, Cold Regions Research & Engineering Laboratory
    Call number: ZSP-202-245
    In: Research report
    Description / Table of Contents: CONTENTS: Preface. - Abstract. - Introduction. - Snow crystals in Greenland. - Microspherules. - Microspherules in snow and ice-fog crystals. - Concentration and radii of spherules. - Discussion and conclusions. - Literature cited.
    Description / Table of Contents: Spherules found in snow crystals, ice-fog crystals, fallout particles, and fly ash were studied with an electron microscope using the electron diffraction method. The central part of the residues of 1004 specimens of natural snow crystals from Greenland, the United States, and Japan were examined; 14 spherules 0.1 to 1.5? in radius were found among them. The residues of 658 artificial ice-fog crystals formed from water vapor in flue gases of coal-burning electric power plants at Fairbanks, Alaska, were also examined; nine spherules were found. Spherules similar to those found in ice-fog residues were found in furnace-produced fly ash fallout at Fairbanks, Alaska. Electron and optical microscope examination of spherules found in Greenland snow reveals a size distribution of the form dN/d(log r) = Cr-ß where ß approximately 3. The properties of spherules and the mean mass of snow crystals from Greenland are described. The electron microscope study indicated that less than 0.7% of the 1004 snow crystals contained spherules of possible extraterrestrial origin, and that snow crystals are formed mainly on clay mineral particles by heterogeneous nucleation.
    Type of Medium: Series available for loan
    Pages: iv, 10 Seite , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 245
    Language: English
    Location: AWI Archive
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