摘要:

A simplified model of the long-wave-reflecting region of the ionosphere, first considered in a previous paper, is used to calculate the theoretical variation of sky wave reflection coefficient with angle of incidence and with the angle of dip of the earth's magnetic field. The resulting curves are found to be in good agreement with experiment. They lead to the conclusion that theoretical results based on the assumption of a vertical magnetic field will not lead to errors in vertical incidence sky wave reflection coefficient greater than about 10%, even though the field is inclined at an angle of as much as 23° to the vertical.

ISSN:1923-4287    

DOI:10.1139/cjr50a-046

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

An atomic beam source and a fast spectrograph which have been used effectively in hyperfine structure investigations are described. The camera objective of the spectrograph is an off-axis paraboloidal mirror. The procedures used to determine the nuclear moments of the two silver isotopes, I = 1/2 for each isotope, μ(Ag107) = − 0.087 n.m. and μ(Ag109) = − 0.160 n.m., are reported.

ISSN:1923-4287    

DOI:10.1139/cjr50a-047

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

It has been customary in applications of diffusion theory to evaporation problems to consider the liquid surface as fixed in solving for the vapor distribution in the adjacent space. A more rigorous treatment, involving solution of the diffusion equation with moving boundaries, has been applied to the problem of evaporation from droplets and flat surfaces. The results indicate that the equations obtained by the method of quasi-stationary states are good to a high degree of approximation under ordinary circumstances.

ISSN:1923-4287    

DOI:10.1139/cjr50a-048

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The evaporation of droplets of 1 to 2 mm. diameter into still air has been studied with nine liquids forming a series of graded volatility from toluene to aniline and including water. The experimental results agreed with calculations based on diffusion and heat transfer theory. The surface temperature of the more volatile droplets was found to be significantly lower than the bulk temperature, in contrast to Johnson's results for water. Convection effects were found to be present with 43 mm. diameter evaporation vessels in confirmation of Gilliland's suggestion, but were absent in the smaller vessels used in the main investigation.

ISSN:1923-4287    

DOI:10.1139/cjr50a-049

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Heat conductivity of natural rubber and GR–S was studied in the range from + 50 °C. to − 170 °C. and from 0 to 100% stretch. The apparatus used was a greatly modified version of one designed by Schallamach. The conductivity of both types of rubber at 0% stretch lies in the range between 3.5 × 10−4and 4.0 × 10−4 cal./sec. cm. deg. C. Stretching increases the rate of change of conductivity with temperature of both natural rubber and GR–S, and decreases the conductivity of the latter. On lowering the temperature and raising it again natural rubber exhibits a complicated hysteresis phenomenon, while GR–S shows a hysteresis loop caused by a second order transition near the brittle point. The hysteresis phenomena of both types of rubber near the second order transition temperature shows considerable similarity to the changes in specific heat observed by Bekkedahl and coworkers. Above and below the transition region the heat conductivity decreases approximately linearly with temperature as might be expected from classical theory. The variation through the second order transition does not agree with classical theory, but may be explained qualitatively on the basis of a diffuse lambda type transition.

ISSN:1923-4287    

DOI:10.1139/cjr50a-050

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

One of the more interesting features of cosmic ray stars is thatnuclei are ejected occasionally in the nuclear disintegrations. Such nuclei are characterized by the fact that, at the end of their range, they suffer radioactive decay (τ = 0.9 sec.) into, which immediately splits up into two oppositely directed α-particles, giving what is usually referred to as a hammer track. In this investigation numerous examples have been observed of the emission of such nuclei in stars in photographic emulsions, the stars having from 2 to 60 prongs. In particular, it has been shown that the energy spectrum of the α-particles forming the hammer tracks is in good agreement with that observed by other workers, and also with experiments made, using the cloud chamber technique, indicating that thein this disintegration is formed in the excited state. When an electron sensitive emulsion is used it is shown that the hammer track is accompanied by thedisintegration electron. The energy spectrum of thenuclei is plotted, and the mechanism of the formation is discussed for both large and small stars.

ISSN:1923-4287    

DOI:10.1139/cjr50a-051

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

not available

ISSN:1923-4287    

DOI:10.1139/cjr50a-052

出版商:NRC Research Press    

年代:1950

数据来源: NRC