ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory  (55)
  • Englisch  (55)
  • Unbestimmte Sprache
  • 1995-1999
  • 1980-1984
  • 1975-1979  (55)
  • 1978  (28)
  • 1977  (27)
  • 1
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/21
    In: CRREL Report, 78-21
    Beschreibung / Inhaltsverzeichnis: This study investigates the possibility of providing estimates of the time of occurrence and length of the freezing season for any location in East and West Germany by using the average Januavy air temperature (AJ AT) as an index. The results indicate that reliable values of the mean freezing index can be obtained from the AJAT relationships which are developed for Germany. This association is further verified using data from the northeastern part of the U.S., and the AJ AT is then used to determine the average starting and ending dates (and hence the probable length) of the freezing season for stations in Germany. The AJ AT and the average dates of snowfall occurrence for numerous locations in the U.S. and Germany are also correlated. Interrelationships between these parameters and the average number of days with snow on the ground for stations up to 3000 m in elevation in Germany are examined. A detailed AJ AT map for East and West Germany, in which data from 134 stations, latitude, altitude and regional influences are considered, is developed in order to make the relationships usable. A historical review of the literature on snow studies in Germany and a brief discussion of snow-cover interpretation by satellite photography are included
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 48 Seiten , Illustrationen , 1 Karte
    Serie: CRREL Report 78-21
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Historical literature review Relationships between midwinter temperature and freezing season Mean freezing index 4 Average January air temperature U.S. comparative study Correlation of AJAT and duration of freezing season Relationships between average January air temperature and snow conditions U.S. relationships German relationships Mapping of average January air temperatures Analysis of observed AJ AT data Development of detailed maps Application and discussion Examples Influence of vegetation Literature cited Appendix A. interpretation of snow cover by satellite Appendix B. Contour, station elevation and Aj AT maps for East and West Germany
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/10
    In: CRREL Report, 78-10
    Beschreibung / Inhaltsverzeichnis: The compressibility of wet snow is described in terms of pressure melting and nonlinear viscous deformation at grain contacts. The results of experiments with different salinities and liquid water contents are compared with computed densities. The decreasing compressibility of wet snow with increasing salinity and decreasing liquid content is quantified and explained. Simultaneous particle growth and the doubly charged layer at phase boundaries are included in the model. The results show that the density of wet snow increases approximately as a power of time but is highly dependent on the stress, initial particle size, liquid water content, and ionic impurity content of the snow.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 23 Seiten , Illustrationen
    Serie: CRREL Report 78-10
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Experimental procedure Grain growth Stressed particle contacts Fluid pressure Packing geometry Temperature distribution and heat flow Fluid and impurity flows Results The liquid film Conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/16
    In: CRREL Report, 78-16
    Beschreibung / Inhaltsverzeichnis: A model investigation of drifting snow conditions was conducted in a hydraulic flume using a sand-water analog. Model results were evaluated to define modeling parameters that would allow quantitative correlation between measured prototype drift conditions and the model. The modeled structure was the standard plan snow fence designed by the Wyoming Highway Department and installed along Interstate Highway 80 in 1971. The performance of this system was documented by the Rocky Mountain Forest and Range Experiment Station of the U.S. Forest Service. Models of the fence were constructed for three heights and two geometric scales. Geometric scaling was based on terrain roughness and boundary layer thickness considerations, while velocity scaling was based on particle fall velocity and threshold of motion characteristics. Simulation of the atmospheric boundary layer was found to be of primary importance. Velocity scaling analysis suggested the use of a 'significant wind' concept based on a combination of velocity magnitude and frequency. Similarity of precipitation rate was not essential, and could be altered within limits to adjust the time scale. The response of the model to the shape of model elements was significant. Although the model is distorted and inexact similarity is achieved, it appears useful on a practical basis.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 26 Seiten , Illustrationen
    Serie: CRREL Report 78-16
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Background Experimental design Similitude considerations The model Model operation Results Velocity Fence height Porosity Model correlation Summary and conclusions Recommeqdations for future work Literature cited Appendix A
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/15
    In: CRREL Report, 78-15
    Beschreibung / Inhaltsverzeichnis: This report first discusses the general approach for calculating the horizontal forces an ice cover exerts on a structure. Ice force determination consists of two parts: (1) the analysis of the in-plane forces assuming that the ice cover remains intact and (2) the use of a failure criterion, since an ice force cannot be larger than the force capable of breaking up the ice cover. For an estimate of the largest ice force, an elastic plate analysis and a failure criterion are often sufficient. A review of the literature revealed that, in the majority of the analyses, it is assumed that the failure load is directly related to a 'crushing strength' of the ice cover. However, observations in the field and tests in the laboratory show that in some instances the ice cover fails by buckling. This report reviews the ice force analyses based on the buckling failure mechanism and points out their shortcomings. The report then presents a new method of analysis which is based on the buckling mechanism
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 13 Seiten , Illustrationen
    Serie: CRREL Report 78-15
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction and statement of problem Review of relevant analyses and tests Determination of the largest ice force on an isolated structure Preliminary remarks The buckling analysis of a floating wedge Proposed method to determine Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/14
    In: CRREL Report, 78-14
    Beschreibung / Inhaltsverzeichnis: The analytical solution and the numerical study of the eigenvalue problem for determining the buckling pressure of an infinite elastic plate floating on water and stressed uniformly along the periphery of an internal hole is presented. The boundary conditions considered are the clamped-, simple-, and free-edge conditions. Small buckling pressure occurs only for the free-edge condition. The shape of the deflection for the free-edge condition suggests that buckling is an important mechanism of failure.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 55 Seiten , Illustrationen
    Serie: CRREL Report 78-14
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction 1. The problem 2. Abstract of the result Part I. Fundamental solutions 3. Fuchsian type solutions 4. Contour integral solution 5. Integration of the integral solution 6. Fundamental solutions for α = 1 7. Fundamental solutions for α = 0 8. Eigenvalues for α = 0 9. Fundamental solutions for α 〉 1 Part II. Asymptotic expansions 10. Asymptotic expansion for 0 〈 α ⩽1 11. Asymptotic expansion for 1 ≦ α ≦ 2 12. Asymptotic expansion for 2 ≦ α ≦ ∞ Part III. Eigenvalues 13. Range of eigenvalues 14. Eigenvalues for the free-edge condition 15. Eigenvalues for the clamped-edge and simple-edge conditions 16. Deflection Acknowledgement Literature cited Appendix A. Analytical continuation at the singular point Appendix B. Tensorial transformations Appendix C. Comparison of the semi-infinite plate buckling with the asymptotic buckling
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/12
    In: CRREL Report, 78-12
    Beschreibung / Inhaltsverzeichnis: Road test sections of membrane-enveloped silt and clay soils overlain with asphalt cement concrete were subjected to repetitive dynamic plate-bearing loadings to determine their strength variations during freeze-thaw cycles. The recoverable surface deformations in the load deflection bowl were continuously measured during the loading cycles and analyzed using the Chevron layered elastic computer program to obtain the in situ resilient deformation modulus of the various section layers at different stages of the freeze-thaw cycles. The resilient stiffness of the pavement system (the total load per unit of resilient load plate deflection) was also calculated for the various freeze-thaw conditions. The modulus values of the asphalt cement concrete varied inversely with its temperature by an order of magnetide (90,000 psi to 1,300,000 psi). The resilient stiffness of the pavement system varied in the same manner by nearly a factor of eight (228.4 kips/in. to 1740.2 kips/in.). Despite the wide strength variations of the sections during freeze-thaw cycles, membrane-enveloped fine-grained soils can be utilized instead of granular materials as base and subbase layers in flexible pavements in cold regions where moisture migration is a major concern. Moisture migration did not occur at saturation levels up to 75%, thus there was no strength loss during thawing.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 24 Seiten , Illustrationen
    Serie: CRREL Report 78-12
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: U.S.customary to metric units of measurement Introduction Freeze-thaw system Construction materials Controlled environment test section Outdoor sections Temperature monitoring instrumentation Repetitive plate bearing test apparatus Test results and analyses Conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/13
    In: CRREL Report, 78-13
    Beschreibung / Inhaltsverzeichnis: Field observations of the growth fabrics of the fast and near-fast ice along the coasts of the Beaufort and Chukchi Seas show that, at depths of more than 60 cm below the upper ice surface, the sea ice crystals show striking alignments within the horizontal plane. At one site this alignment was well developed at a depth of 15 cm and in all cases the degree of preferred orientation increased with depth, with the strongest orientations occurring at the bottom of the ice sheet. In general the c-axes of the crystals were aligned roughly E-W parallel to the coast. In the vicinity of islands the alignment roughly paralleled the outlines of the islands and in narrow passes between islands the alignment paralleled the channel. Our observations, as well as similar observations made in the Kara Sea by Cherepanov, can be explained if it is assumed that the c-axes of the crystals are aligned parallel to the 'long-term' current direction at the sea ice/sea water interface. The alignments are believed to be the result of geometric selection among the growing crystals, with the most favored orientation being that in which the current flows normal to the (0001) plates of ice that make up the dendritic ice/water interface characteristics of sea ice. It is hypothesized that current flow in this direction reduces the thickness of the solute boundary layer as well as the salinity in the liquid at the interface. This lowered salinity allows crystals in the favored orientation to extend farther into the melt than neighboring crystals with less favored orientations. In addition the current tends to induce a continuous flux of supercooled seawater against the sides of the crystals that extend ahead of the interface.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 29 Seiten , Illustrationen
    Serie: CRREL Report 78-13
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Locale and techniques Observations Vertical variations in crystal orientation Regional variations in crystal orientation Summary of observations Causes Initial ice skim Earth’s magnetic field Currents Conclusions and consequences Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Signatur: ZSP-201-78/28
    In: CRREL Report, 78-28
    Materialart: Schriftenreihen ausleihbar
    Seiten: x, 112 Seiten , Illustrationen
    Serie: CRREL Report 78-28
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors Introduction Descriptions of road test sections Test equipment and procedures Field repetitive plate bearing tests Data analysis General Layered-elastic analysis of the pavement systems Statistical analysis Flexural analysis Summary and conclusions Literature cited Appendix A: Resilient surface deflections for the test points
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/22
    In: CRREL Report, 78-22
    Beschreibung / Inhaltsverzeichnis: Special environmental factors that influence the design, laying and maintenance of undersea pipelines and cables in polar waters are described. Various approaches to the protection of submarine pipes and cables are considered, and prime emphasis is given to burial techniques for shallow water. A wide range of methods for trenching and burying are discussed, and technical data are given.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 36 Seiten , Illustrationen
    Serie: CRREL Report 78-22
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors Introduction Types of pipelines and cables Potential hazards to pipelines and cables Areas of concern Waterdepth Sea ice Icebergs and ice islands Submarine permafrost Ice gouging Seabed erosion by water jets Protection methods Protection of unburied pipes and cables Protection by burial Backhoe digging Wireline equipment Plowing and ripping from the surface Plowing and ripping by self-propelled seabed vehicles Bucket ladder dredges Suction dredging Conventional cutterhead dredges Low pressure water jetting Bottom-traveling cutterhead dredges Explosive methods Novel methods Disc saws, wheel ditchers and milling drums Ladder trenchers and chain saws Repetitive impulse devices High pressure water jets Flame jets and plasma torches Electrical discharge and electromagnetic radiation Chemical methods Conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 11
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 12
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 13
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 14
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 15
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 16
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/27
    In: CRREL Report, 78-27
    Beschreibung / Inhaltsverzeichnis: Uniaxial compression and tension tests were conducted on polycrystalline snow-ice to determine the effect of temperature on its strength. Test temperatures ranged from -O.1C to -54C. Two machine speeds, 0.847 mm/s and84.7 mm/s were used for the constant displacement rate tests. The compressive strength at -54C was about oneorder of magnitude higher than at -0.1C. The tensile strength at -18C was about 20% higher than at 0.1C. The initial tangent and 50% strength moduli are given for the compression tests, while the secant modulus to failure is given for the tension tests.The mode of fracture is discussed and the test results are compared with data from other investigations.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 22 Seiten , Illustrationen
    Serie: CRREL Report 78-27
    Sprache: Englisch
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 17
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/19
    In: CRREL Report, 78-19
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 21 Seiten , Illustrationen
    Serie: CRREL Report 78-19
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Previous work Methods and results Methods of analysis Salinity-chlorophyll a associations Discussion Comparison of ice and water column standing crops Estimated mass of ice associated chl. a Mechanism of ice algae formation in the Weddell Sea Differences between the biological environments of fast and drifting pack ice Conclusions Literature cited Appendix A. Species variations - ice and water column
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 18
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/26
    In: CRREL Report, 78-26
    Beschreibung / Inhaltsverzeichnis: Ice fog suppression experiments on the Fort Wainwright Power Plant cooling pond were conducted during the winters of 1974-76. Baseline information studies occupied a sizable portion of the available ice fog weather in 1974-75. Then hexadecanol was added to the pond and dramatically improved visibility by reducing fog generated from water vapor released by the pond at -14 C. Although this temperature was not low enough to create ice fog, the cold vapor fog created was equally as devastating to visibility in the vicinity of the pond. During the winter of 1975-76, suppression tests were continued using films of hexadecanol, mixes of hexadecanol and octadecanol, and ethylene glycol monobutyl ether (EGME). Suppression effectiveness at colder temperatures was stuided and limits to the techniques were probed. A reinforcing grid was constructed that prevented breakup of the film by wind and water currents. Lifetime tests indicated that EGME degrades much more slowly than either hexadecanol or the hexadecanol-octadecanol mix. The films were found to be very effective fog reducers at warmer temperatures but still allowed 20% to 40% of normal evaporation to occur. The vapor thus produced was sufficient to create some ice fog at lower temperatures, but this ice fog occurred less frequently and was more quickly dispersed than the thick fog that was present before application of the films.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 27 Seiten , Illustrationen
    Serie: CRREL Report 78-26
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Ice fog from cooling ponds Evaporation Relative humidity and cold air Ice fog suppression Air movement Plastic films Rafts Injection wells Cooling towers Chemical films Reinforced film experiments Meteorological data collection Floating reinforcement grid Application of the hexadecanol film Hexadecanol, octadecanol mixes Ethylene glycol monobutyl ether Laboratory tests of suppression effectiveness Conclusions Literature cited Appendix A. Design for an automatic thin chemical film applicationsystem Appendix B. Meteorological data
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 19
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/18
    In: CRREL Report, 78-18
    Beschreibung / Inhaltsverzeichnis: The primary objective of this project was to demonstrate the utility of remote sensing techniques as an operational tool in the acquisition of data required by the U.S. Army Corps of Engineers, Seattle District, in the Grays Harbor dredging effects project, and related projects. Aerial imagery was used to map surface circulation and suspended sediment patterns near the hopper dredge pump site at the harbor entrance and near pulpmill outfalls in Aberdeen, and to map the areal distribution and extent of intertidal habitats. The surface circulation maps prepared from the aerial photographs and thermal imagery compared favorably with the large-scale circulation patterns observed in the Grays Harbor hydraulic model at the U.S. Army Engineer Waterways Experiment Station. Of the imagery provided by NASA, the thermal imagery was more useful than the color or color infrared (CIR) photographs for mapping circula­tion, while the CIR photographs were more useful than the thermal imagery or the color photographs for mapping intertidal habitats. Current velocities estimated from dye dispersion patterns and drifting dye drogues were comparable at some locations to velocities measured by in situ current meters and in the hydraulic model. Based on a cursory evaluation of LANDSAT-1 imagery acquired in January, February, and October 1973, it had limited utility in providing data on surface circulation patterns in Grays Harbor. The areal distribution and extent of nine wetland vegetation types, dune vegetation, and three types of eelgrass were mapped using primarily aerial C IR photographs and ground sur­veys. Color photographs were also used for areas not covered by the C IR photographs. Wetland vegetation types mapped were: low silty marsh, low sandy marsh, sedge marsh, high immature marsh, high mature marsh, salt marsh, diked pasture, freshwater marsh, and wooded swamp. Undiked salt marsh (first five types) covered 5540 acres (22.3 km2) in Grays Harbor.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 85 Seiten , Illustrationen
    Serie: CRREL Report 78-18
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Site description Background and objectives Project history Approach General Aircraft imagery and sensor data LANDSAT imagery Ground truth data Results and discussion Remote sensing techniques Conventional techniques Comparison of results Conclusions Advantages and disadvantages Applications Recommendations Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 20
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 21
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 22
    Signatur: ZSP-201-78/9
    In: CRREL Report, 78-9
    Beschreibung / Inhaltsverzeichnis: Large, simply supported beams of temperate lake ice were found, generally, to yield significantly higher flexural strengths than the same beams tested in the cantilever mode. Data support the view that a significant stress concentration may exist at the fixed corners of the cantilever beams. Maximum effects are experienced with beams of cold, brittle ice substantially free of structural imperfections; for this kind of ice the strength difference factor, here attributed to the effect of stress concentrations, may exceed 2.0; that is, simply supported beams test a factor of 2 or more stronger than the same beams tested in the cantilever mode. In ice that has undergone extensive thermal degradation, the stress concentration effect may be eliminated entirely. Simply supported beams generally yield higher strengths when the top surfaces are placed in tension. This behavior is attributed to differences in ice type; the fine-grained, crack-free top layer of snow-ice which constituted up to 50% of the ice cover in the current series of tests usually reacted more strongly in tension than the coarse-grained crack-prone bottom lake ice.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 14 Seiten , Illustrationen
    Serie: CRREL Report 78-9
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Test sites and ice cover properties Beam testing Results Discussion Conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 23
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/2
    In: CRREL Report, 78-2
    Beschreibung / Inhaltsverzeichnis: Many of the technical questions relating to iceberg transport are given brief, but quantitative, consideration. These include iceberg genesis and properties, the mechanical stability of icebergs at sea, towing forces and tug characteristics, drag coefficients, ablation rates, and handling and processing the iceberg at both the pick-up site and at the final destination. In particular the paper attempts to make technical information on glaciological and ice engineering aspects of the problem more readily available to the interested planner or engineer. Specific conclusions include: (1) No unprotected iceberg, no matter how long or wide, would be likely to survive the ablation caused by a long trip to low latitudes. (2) Icebergs that have a horizontal dimension exceeding 2 km may well be prone to breakup by long wavelength swells. (3) To avoid the dangers associated with an iceberg capsizing, the width of a 200-m thick iceberg should always be more than 300 m. (4) For towing efficiency the length/width ratio of a towed iceberg should be appreciably greater than unity. (5) For a pilot project, the selected iceberg would have to be quite small, if for no other reason than the practical availability of tug power.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 31 Seiten , Illustrationen
    Serie: CRREL Report 78-2
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Sources and properties of tabular icebergs Sources Characteristics of ice shelves near the ice front Characteristics of tabular icebergs Towing Geophysical and engineering considerations Tug characteristics Handling and processing Cutting and boring with thermal devices Penetration with electrothermal devices Electrothermal cutting Making vertical cuts by pre-split blasting Primary fragmentation by blasting Primary fragmentation by mechanical sawing Comminuting ice with machines Slurry pipelines Conclusion Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 24
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 25
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 26
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 27
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 28
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 29
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 30
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 31
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/24
    In: CRREL Report, 78-24
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 12 Seiten , Illustrationen
    Serie: CRREL Report 78-24
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Comparison of winters Ship effects Measured forces Sequential breaking of the structure Discussion Conclusions Recommendations Literature cited Appendix A. Force level fluctuations in west ice boom, 20 January 1977
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 32
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/20
    In: CRREL Report, 78-20
    Beschreibung / Inhaltsverzeichnis: Abstract: Measurements of the concentrations of Aitken nuclei in maritime air were made near Barrow, Alaska, in June 1975 with a modified Nolan-Pollack small-particle detector. The concentrations varied from 50 to 300 particles cm^-3 depending upon meteorological conditions. The mean Aitken nuclei count was 100 particles cm^-3 for diameters greater than 2 x 10^-3 μm. Transmission electron micrographs of aerosols in maritime air near Barrow were taken. The size range was measured to be 0.01 to 2.5 μm in diameter with the most frequently observed diameter being 0.04 μm. The volume of the maritime air and the collection efficiency of aerosol particles on filmed grids for electron microscopy were measured. The aerosol concentrations were found to be 76 to 101 particles cm^-3 ; the mean concentration was calculated to be 87 particles cm^-3. The aerosol particles in the maritime air were identified by electron microscopy and selected area electron diffraction analysis. About 20% of the aerosol particles were identified, and 80% of the particles were too small for electron diffraction analysis. Sea salt particles constituted 2% of the total, and clay minerals 3%; these particles were considered to be of natural origin. Solid combustion by-products such as coagulated carbon particles and fly ash particles constituted 16%. Despite the comparative remoteness of the sampling site, the measurements indicate that many anthropogenic aerosols were found using an electron microscope.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 48 Seiten , Illustrationen
    Serie: CRREL Report 78-20
    Sprache: Englisch
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 33
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/8
    In: CRREL Report, 78-8
    Beschreibung / Inhaltsverzeichnis: The interaction of a 5.1-GHz transverse electric surface wave with a dielectric slab is experimentally investigated. The wave is initially supported by a dielectric substrate resting upon a metallic ground-plane. A slab, made of the same dielectric material as the substrate and variable in height, is then placed upon the waveguide. The results for a small slab sitting on the substrate showed that the discontinuity was a very inefficient launcher of reflected surface waves. Investigations of these reflections with a trough waveguide showed that, for values of slab height comparable to the exponential decay height of the surface wave, the reflections remain very small. However, as the slab height is increased beyond the decay height, the reflected amplitude approaches the theoretical value for a plane wave reflected from the interface between air and the same dielectric. The results are applicable to surface wave methods of microwave deicing of wings and helicopter rotors.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 16 Seiten , Illustrationen
    Serie: CRREL Report 78-8
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Summary Introduction Background Objective and procedure Theory of plane surface waves Waveguide design and characteristics Physical apparatus Frequency characteristics Spatial distribution of Ey above the guide Guide wave length Surface wave interaction with a slab discontinuity Experiments with a trough Discussion and conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 34
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/5
    In: CRREL Report, 78-5
    Beschreibung / Inhaltsverzeichnis: The viscoelastic deflection of an infinite floating ice plate subjected to a circular load was solved, assuming the Maxwell-Voigt type four-element model. An effective method of numerical integration of the solution integrals was developed, of which each integrand contains a product of Bessel functions extending to infinity. The theoretical curve was fitted to the field data, but the material constants thus found varied with time and location.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 32 Seiten , Illustrationen
    Serie: CRREL Report 78-5
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction The problem The solution Method of numerical integration Ramp/steady loading Curve fitting to time lapse deflections Asymptotic deflection Deflection profiles Acknowledgement Literature cited Appendix I. Analytical background Appendix II. Computer programs, ramp time profiles and steady time profiles
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 35
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/6
    In: CRREL Report, 78-6
    Beschreibung / Inhaltsverzeichnis: A new freezing mechanism, called segregation freezing, is proposed to explain the generation of the suction force that draws pore water up to the freezing surface of a growing ice lens. The segregation freezing temperature is derived by applying thermodynamics to a soil mechanics concept that distinguishes the effective pressure from the neutral pressure. The frost-heaving pressure is formulated in the solution of the differential equations of the simultaneous flow of heat and water, of which the segregation freezing temperature is one of the boundary conditions.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 13 Seiten , Illustrationen
    Serie: CRREL Report 78-6
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Segregation freezing Analysis Heat conduction in the nascent ice layer Water flow in the unfrozen soil Heat transfer in the unfrozen soil Energy balance at the segregation-freezing front Numerical computation Literature cited Appendix A. Essence of Portnov’s method Appendix B. Frost-heaving without air available
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 36
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/1
    In: CRREL Report, 78-1
    Beschreibung / Inhaltsverzeichnis: The results of axial double point-load tests on disk samples of snow and ice obtained from the area of McMurdo Sound, Antarctica, are presented. They show the effects of temperature, sample length, load point diameter and specific gravity on failure load. It was determined that 13 samples should be tested to obtain a representative mean strength index. The results show that the axial double point-load test has good possibilities as a rapid field test for determining the unconfined comrpessive strength of snow and ice but that further evaluation of the variables affecting test results must be made.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 11 Seiten , Illustrationen
    Serie: CRREL Report 78-1
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Test procedure Test program Test samples Number of test for determining strength index Effect of temperature Effect of sample length Effect of load point size Tests on snow Discussion Recommendations Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 37
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 38
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 39
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/25
    In: CRREL Report, 78-25
    Beschreibung / Inhaltsverzeichnis: The objectives of this investigation were to describe channel characteristics and geographic settings of ice jam sites from aerial photographic interpretation, to indicate which characteristics may be important in causing ice jams, and to suggest additional uses of aerial photographs. Aerial photographs were taken of 19 sites with a Zeiss RMK 15/23 aerial camera on 17, 19, and 21 April 1976. Uncontrolled photomosaics of each site were assembled and major river characteristics were delineated on the photomosaics. Characteristics described include: manmade structures, falls, rapids, changes in channel depths, channel islands, mid-channel shoals or bars, river bed material, river sinuosity, meanders, floodplain width, riparian vegetation, and types of development on the floodplain. River channel widths were measured from the photographs along rivers where ground truth data were available for comparison. Lengths of channel riffles and pools were measured along the rivers where variations in river depths were evident on the photographs. Seventy-nine percent of the sites have some form of flow control structure which causes a pool with a backwater condition of low velocity. The low flow condition in the pool allows a solid ice cover to form which impedes ice movement and initiates ice jams. Aerial photographs provide a regional perspective for evaluating channel characteristics at an ice jam site and for analyzing the geographic setting at each site during ice-free conditions. Photographs taken after ice jams have formed are useful in monitoring ice jam formation, in analyzing ice characteristics, and in documenting ice jam breakup and movement.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 60 Seiten , Illustrationen
    Serie: CRREL Report 78-25
    Sprache: Englisch
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 40
    Signatur: ZSP-201-78/23
    In: CRREL Report, 78-23
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 53 Seiten , Illustrationen
    Serie: CRREL Report 78-23
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Conversion factors: Metric (SI) to U.S. customary units of measurement Introduction Selection of experimental approach Previous investigations of effect of freeze-thaw on soil deform ability Selection of laboratory test method Selection of method of field validation tests Field repeated-load plate-bearing tests Test pavements, soils and materials Test procedures and results Resilient modulus of subgrade calculated from field tests Mathematical model Characterization of asphalt concrete Characterization of frozen silt Calculated resilient modulus of silt within the zone of freezing Laboratory repeated-load triaxial tests Specimens, equipment and testing procedures Apparatus Procedures Resilient properties calculated from laboratory tests Calculation methods Asphalt concrete - test results Asphalt concrete - statistical analysis and discussion Silt - test results Silt - statistical analysis Discussion and conclusions Literature cited Appendix A. Repeated-load plate-bearing test results Appendix B. Laboratory repeated-load triaxial test results Appendix C. Regression equation coefficients for resilient modulus and Poisson’s ratio from repeated-load triaxial test data on asphalt concrete and silt Appendix D. Detailed procedures for repeated-load triaxial testing
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 41
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/17
    In: CRREL Report, 78-17
    Beschreibung / Inhaltsverzeichnis: Abstract: This investigation utilized historical and recent aerial photographs and satellite imagery in 1) estimating changes in positions of the high-water line and sea cliff break and base, in rates of accretion and/or erosion, and in volumes of transported sediment, and 2) providing a preliminary evaluation of the direction of littoral transport along the outer Cape Cod coast. Using aerial photographs acquired in 1938, 1952, 1971 and 1974 with manual photointerpretation techniques, changes in the distances from selected reference points to the cliff break, cliff base and the high-water line were measured. LANDSAT-1 and -2 imagery acquired from 1 September 1972 to 28 May 1975 was evaluated for use in determining the directions of littoral transport that are active the predominant amount of time. Although the imagery has been very useful for this purpose at other locations, it proved to be useless along the outer shore of Cape Cod. Largest net migrations of the high water line from 1938 to 1974 occurred in the northern and southern portions of this coast. The northern maximum high water line was 321.4 ft, the southern was 1794.6 ft. The central portion of the coast was generally more stable with changes varying from 6.8 to 157.6 ft. Cliff-base recession rates varied from 0.4 to 7.3 ft/yr. Maximum estimated net volume of sediment deposited per linear foot of beach from 1938 to 1974 was 334 yd^3 (based on 2 yd^3/ft of recession or accretion); maximum eroded was 914 yd^3. Changes in the configuration of spits were used to evaluate directions of littoral transport since suspended sediment concentrations were generally not sufficient to act as natural tracers of surface currents. Based on the literature and a determination of the portion of the coast perpendicular to the direction of dominant wave approach, the location of the nodal zone for predominant littoral directions of drift probably shifts between the area near Spectacle Pond and North Truro Air Force Station. This investigation has illustrated a photo interpretation technique that is useful in performing a reconnaissance of coastal change. The data obtained from this method can be used to supplement those acquired by ground surveys and are valid as first approximations for planning subsequent, more detailed surveys.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 49 Seiten , Illustrationen
    Serie: CRREL Report 78-17
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: U.S. customary to metric units of measurement Introduction Background Previous investigations Analytical procedures Results and discussion Shoreline changes: High-water line Shoreline changes: Cliff recession Volumetric changes Nodal zone location and direction of littoral transport Error evaluation Summary and conclusions Future research Selected bibliography Appendix A: Maps of shoreline with overlays for 1938, 1952, 1971 and 1974 Appendix B: Supplementary data for estimating shoreline change
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 42
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/7
    In: CRREL Report, 78-7
    Beschreibung / Inhaltsverzeichnis: The theory of non-coaxial in-plane plastic deformation of soils that obey the Coulomb yield criterion is presented. The constitutive equations are derived by use of the geometry of the Mohr circle and the theory of characteristic lines. It is found that, for solving a boundary value problem, the non-coaxial angle must be given such values that enable us to accommodate the presupposed type of flow in the given domain satisfying the given boundary conditions. The non-coaxial angle is contained in the constitutive equations as a parameter. Therefore, the plastic material obeying the Coulomb yield criterion is a singular material whose constitutive equations are not constant with material but are variable with flow conditions.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 28 Seiten , Illustrationen
    Serie: CRREL Report 78-7
    Sprache: Englisch
    Anmerkung: CONTENTS Abstrac Preface Introduction Analysis of stress Geometry of the Mohr circle Stress characteristic directions Analysis of strain rate Constitutive equations Strain-rate characteristic directions Constitutive geometry Strain-rate tensor The dyadic expression Plastic work rate Coordinate transformation Example The stress solution Velocity equations in the a-characteristic curvilinear coordinates The constant speed solution Velocity equations in the constant density region Solution in the first constant-density subregion Solution in the second constant-density subregion Solution in the passive region Conclusion Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 43
    Signatur: ZSP-201-78/4
    In: CRREL Report, 78-4
    Beschreibung / Inhaltsverzeichnis: The use of radio-echo sounding records to indicate the presence of internal layers within large ice sheets is of interest to glaciologists because it offers a means of tracking the internal properties of the ice sheets over large distances. The interpretation of the reflections obtained in this manner is more valuable, however, if a physical property change relating to the glaciological regime can be related to the dielectric property change producing the radio-echo reflections. In this report, we use the measured physical properties of core to bedrock taken at Cape Folger, East Antarctica (66 deg 22 min s, 111 deg (E), 324-m depth), to compute a profile of dielectric properties and from this, a depth-reflection coefficient profile for comparison with observed radio-echo reflections. The measurements available on physical properties are: density variations, bubble size and shape changes, and crystal fabric variations. The depths of the strong reflections shown on the available radio-echo records are in reasonable agreement with the depths corresponding to the highest reflection coefficients computed from the combined physical property measurements. In calculations to differentiate the separate effects of different physical properties, it appears that density variations account for the primary contributions to the calculated dielectric property changes corresponding to the highest reflection coefficients. However, bubble changes alone can also account for reasonable, though lower, reflection coefficients at the appropriate depths. Crystal fabric variations correspond poorly with the reflection locations. Density variations are normally associated with depositional events in the history of the ice sheet.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 12 Seiten , Illustrationen
    Serie: CRREL Report 78-4
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Derivation of the power reflection coefficient-depth variation Possible sources of dielectric constant variation with depth in ice sheets Ice density variations Effect of macroscopic impurity layers Effect of microscopic impurtty layers Changes in inclusion geometry Effect of crystal orientation changes Physical properties of the Cape Folger core Density-depth profile Air bubble-geometry depth profile Crystal orientation-depth profile Radio-echo sounding data Results and conclusions Literature cited
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 44
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/3
    In: CRREL Report, 78-3
    Beschreibung / Inhaltsverzeichnis: The mathematical theory for the bearing capacity of river ice for vehicles is presented. The floating ice sheet is assumed to have simple supports at the shore line. Solutions are presented for loads uniformly distributed over circular and rectangular areas. Numerical evaluations are made for a number of vehicles and the results presented in graphical form
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 22 Seiten , Illustrationen
    Serie: CRREL Report 78-3
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Conversion factors: U.S. customary to metric (SI) units of measurement Introduction Theory Solution by superposition Solution by Fourier integral Solution by Fourier series Application and results Literature cited Appendix A: Bearing capacity of river ice for military vehicles Appendix B: Vehicle specifications Appendix C: Fortran II computer program
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 45
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 46
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 47
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 48
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 49
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 50
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 16 Seiten , Illustrationen
    Serie: CRREL Report 77-2
    Sprache: Englisch
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 51
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 52
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 53
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 54
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    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
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 55
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-78/11
    In: CRREL Report, 78-11
    In: Mechanics of cutting and boring, Part VIII
    Beschreibung / Inhaltsverzeichnis: The report deals with forces and power requirements for cutting machines of the belt type, as exemplified by large chain saws and ladder trenchers. The forces of single cutting tools are considered, and related to the overall forces on a cutter bar. Forces are related to power, and sources of loss are identified. Tractive thrust and normal reaction are analyzed and used to assess the traction, weight and balance.
    Materialart: Schriftenreihen ausleihbar
    Seiten: vi, 24 Seiten , Illustrationen
    Serie: CRREL Report 78-11
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Foreword Introduction Terminology Tool forces Number of active cutting teeth Tool force and chain force Chain power Tool turce and belt power Tractive thrust and normal reaction Traction of carrier vehicles Power/weight ratio Cutter bar moments Specific energy Performance index Power density Apparent belt pressure Acceleratin and transport of cuttings Examples
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...