摘要:

An objective method of measuring color temperature is described, using apparatus found in nearly every photometric laboratory.

ISSN:1923-4287    

DOI:10.1139/cjr48a-003

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The modified Kozeny equation has been found to be satisfactory for the measurement of the specific surfaces of carbon blacks having average particle diameters ranging from 0.01 to 0.1 μ to within ±10%. Comparative data were obtained from electron microscope counting and from low temperature nitrogen adsorption isotherms. The three methods examined gave results that were in satisfactory agreement, except when the carbon black was porous, and then the adsorption value was extremely large.

ISSN:1923-4287    

DOI:10.1139/cjr48a-004

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Variations that occur in intensity ratios belonging to pairs of elements on the addition of various extraneous substances to standard samples have been studied using a common type of condensed spark discharge. The extent of the variations depended on the test elements chosen, the nature of the added substance, the line pair investigated, and on whether or not the standard samples were buffered. The variations bore no apparent relation to the relative ionization potentials or atomic weights of the test elements, nor to any physical property of the added substances. In general, they were smaller for the line pairs having the most nearly equal excitation potentials. Usually, but not always, they were smaller for buffered than for unbuffered samples. Illumination of the electrodes with ultraviolet light, though resulting in steadier operation of the discharge, or alterations of the capacity in the sparking circuit did not reduce the variations materially. Operation of the discharge at constant current coupled with the use of a buffer however did reduce the variations considerably for the instances studied.

ISSN:1923-4287    

DOI:10.1139/cjr48a-005

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A slightly modified form of the rapid and simple method suggested by Hutchinson for the measurement of the thermal conductivity of liquids has been found to suffer from convection effects with samples of low viscosity, except with conductivity tubes of very small diameter. For more viscous liquids such as glycerol it was found to be adequate under all conditions studied. The method has been applied in the determination of the conductivity of Napalm–gasoline gels. For temperaturesTbetween − 50° and 50 °C., and Napalm concentrationsCbetween 0 and 10%, the conductivitykin cal. sec.−1cm.−1per degree C. is described to better than 1% by the relation,k × 105 = 29.7 − 0.068T + 0.11C. The temperature coefficient of resistance of the unaged tungsten filaments used in the tubes differed considerably from the value given by the International Critical Tables for aged tungsten filaments. For temperaturesT0between − 50° and 50 °C., the coefficient α0per degree C. is given to better than 1% by the relation,.

ISSN:1923-4287    

DOI:10.1139/cjr48a-006

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Experiments are reported that show the relations existing between gamma, useful exposure range for aerial photography, maximum resolving power, and emulsion speed as determined by the resolving power criterion. Aero Super XX and Panatomic X, processed in various ways, were used for the experiments. The results are used to deduce the proper choice of emulsion and processing technique for ordinary daylight aerial photography where the main requirement is the acquisition of information.

ISSN:1923-4287    

DOI:10.1139/cjr48a-007

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A broadside dipole array, or 'billboard', with a greatly simplified feed and matching system, is described. Radiation patterns compare favorably with those of the conventional billboard.

ISSN:1923-4287    

DOI:10.1139/cjr48a-008

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Positive ions are formed in a low pressure electrodeless discharge which is excited by the radio-frequency field of a coil coupled to a 15 Mc. per sec. oscillator. The ions are extracted from the discharge through a pumping canal (2 mm. in diameter × 12 mm. in length) by a simple arrangement of electrodes. After further focusing and acceleration to 50 kv., the beam current at the target is 500 μa. and the focal spot is 6 mm. in diameter. Magnetic analysis has shown that the beam consists of 50% protons when using hydrogen in the discharge and 60% deuterons when using deuterium. Gas is supplied to the source at the rate of 15 cc. per hr.

ISSN:1923-4287    

DOI:10.1139/cjr48a-009

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

This paper describes measurements which have been made on the coincidence counting rate between the fissions produced in an ionization chamber and the discharges of a Geiger counter. By determining the absolute efficiency of the counter, the total energy emitted in the form of γ-radiation was estimated to be about 4.6 ± 1.0 Mev. Measurements have been made on the range of the electrons projected from an aluminum radiator placed between the ionization chamber and two thin-walled counters. From this experiment, the average energy of the radiation appears to be about 2.5 Mev. The result is confirmed by absorption measurements in lead. The absorption curve indicates a fairly homogeneous radiation and gives some evidence for the existence of a softer component with an energy of about 500 kev.

ISSN:1923-4287    

DOI:10.1139/cjr48a-010

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A method is developed for determining the moments of the angular distribution of monoenergetic neutrons diffusing inside a homogeneous medium. It is applicable to the 'asymptotic' region, i.e., the region in which surface effects may be neglected. In particular, a general derivation is given for the current-density relation, involving no assumptions about the relative cross sections for scattering and capture. The second moment is expressed in terms of derivatives of the density, and the analogous procedure for higher moments is indicated. Moments of the angular distribution relative to arbitrary directions in space are defined: general formulae and applications to special cases are given for the second moment. Comparison may be made with the results of elementary diffusion theory, in which the angular distribution is assumed to be essentially linear.

ISSN:1923-4287    

DOI:10.1139/cjr48a-011

出版商:NRC Research Press    

年代:1948

数据来源: NRC