摘要:

AbstractIn order to determine the influence of shear velocity (U*), bed roughness (k) and moving particle diameter (d) on particle bed-load transport, velocities of single spherical glass beads (Vp) moving over beds of rhombohedrally packed spherical glass beads were determined under controlled laboratory conditions for several values of U*,kandd.A relationship between the position of zero water velocity (z1) and bed roughness (k) is established.Three“stages”of particle motion are recognized from a plot ofVpond.The degree of development of each is a function of all three major variables.An empirical solution is offered whereVpis considered a function of (U*,kandd.A more detailed consideration of the forces which tend to propel and retard a moving particle leads to the development of a semi-empirical expression for the velocity of a single particle in contact-load motion.—A list of symbols is found at the end of the paper.

ISSN:0435-3676    

DOI:10.1080/04353676.1966.11879737

出版商:Taylor&Francis    

年代:1966

数据来源: Taylor

摘要:

AbstractThe mean annual range of temperature, and the standard deviation of hourly temperatures around the annual mean were compared for several dozen stations differing greatly in latitude and continentality. The two measures of dispersion display a linear relation, and a straight-line equation fitted by least squares allows the standard deviation to be computed from the range with a standard error little greater than I deg F., leading to the suggestion that frequencies and extremes can be estimated with sufficient accuracy for some purposes by starting with data limited to the means of the warmest and coldest months of the year.Examination of error patterns showed that standard deviations observed in continental stations are larger, and those in marine exposures smaller, than computed from the mean annual range. The departures are consistent with the response of the standard deviation to scatter caused by short-term fluctuations lost in monthly means. The standard deviation is thus the more accurate measure of dispersion, and its use in indices of continentality and the like is suggested. Errors did not increase progressively with the range, however, which led to examination of variance.Decomposition of the equations expressing variance in terms of the range show 1) the input of a sine wave relatable to the annual march of temperature, and 2) a term giving the dispersions stemming from the daily range of temperature plus irregular fluctuations. The growth of the first term relative to that of the second explains the linear relation seen in the scatter diagram initially plotted, and also sheds new light on comparative temperature regimes. If seasonal differences are slight, temperature variability must relate mainly to the daily cycle and whatever irregular fluctuations may be present, but where the mean annual range increases to much more than 20 deg (F), all stations in the sample agreed in showing the annual march of temperature the chief contributor to the variance of hourly temperatures around the annual mean.

ISSN:0435-3676    

DOI:10.1080/04353676.1966.11879738

出版商:Taylor&Francis    

年代:1966

数据来源: Taylor

摘要:

AbstractThis report, based on field work along the Colville River, Alaska, presents hydrological characteristics of the surface drainage in an area of continuous permafrost on the Arctic Slope. Water discharge was determined for the river delta during the whole hydrological year, which in 1962 lasted from May 25 to about October 20. During this period the discharge started from zero and reached about 6 000 m3/s during the flood at the beginning of June. The total water discharge during the year was 16×109m3with an average of 26 1/s/km2for the hydrological year or 10 1/s/km2for the entire year.

ISSN:0435-3676    

DOI:10.1080/04353676.1966.11879739

出版商:Taylor&Francis    

年代:1966

数据来源: Taylor

摘要:

AbstractPart of a relict frost wedge polygonal ground pattern penetrating a till sheet is described. Evidence is presented which suggests that the feature is a sand wedge polygon on both lithological and genetic criteria. The age relationship indicate that it must post date the Late Weichselian maximum in north-western England.

ISSN:0435-3676    

DOI:10.1080/04353676.1966.11879740

出版商:Taylor&Francis    

年代:1966

数据来源: Taylor

ISSN:0435-3676    

DOI:10.1080/04353676.1966.11879741

出版商:Taylor&Francis    

年代:1966

数据来源: Taylor

ISSN:0435-3676    

DOI:10.1080/04353676.1966.11879742

出版商:Taylor&Francis    

年代:1966

数据来源: Taylor