New Method For Calibration Research Articles

Calibration of paramagnetic thermometers using superconductive fixed points

A new method for calibration of paramagnetic materials is described. The technique consists of fitting the temperature-dependent mutual inductance of a coil set surrounding a paramagnetic material to a Curie Law using the superconductive transitions of several elements as thermometric fixed points. As a particular demonstration of this technique, the paramagnetic salt, cerous magnesium nitrate, was calibrated using the superconductive transitions of aluminium, zinc, and cadmium. The temperature scale obtained in this way was used in a study of the superconductive properties of iridium.

New method for calibration of permeation wafer and diffusion devices

New method for calibration of permeation wafer and diffusion devices

Calibration of microwave network analyser for computer-corrected S parameter measurements

A new method of calibration that uses three short-circuits (one direct and two offset short-circuits) enables the scattering parameters of the error network to be evaluated, and makes corrected measurements of the reflection coefficients possible without requiring the use of matched terminations. The theoretical results are confirmed by experimental results.

Spectrophotometry of M and C Stars

Abstract and SummarySurveys of M and C stars down to infrared magnitudes 12.m0 in two galactic regions in the direction Cygnus and anticentre are described. Infrared magnitudes are derived by a new method of calibration based on the use of a combination of crossed calcite plates and Polaroid HN32. Spectral classification is based on spectrophotometric criteria which measure the relative strengths of the molecular bands visible in the infrared in the low dispersion objective prism spectra. Infrared absolute magnitudes and interstellar extinction in the infrared are obtained from the present material and published data, and the space densities of M stars are determined.Full accounts have been published in Publ. Edinburgh Roy. Obs.7, 1 (1970) and 7, 73 (1971).

Absolute calibration of a class of torque-operated microwave wattmeters incorporating resistive elements

A general method of calibration suitable for loss-free (or low-loss) torque-operated microwave wattmeters has been developed by the author in a previous paper. The present paper describes an extension of that theory to cover the case of a wattmeter of which a component part is a lossy element in which a fraction of the power to be measured is dissipated.To apply the method, it is necessary that the lossy element be detachable, so that it can be replaced by a movable short-circuit.An example of such an instrument is the microwave analogue of the electrostatic wattmeter, recently proposed by Barlow.The new method of calibration was developed with particular reference to that instrument, though it is capable of somewhat wider application.

Determination of Small Amounts of an Element in a Powder without the AID of Standard Samples

A new method of calibration for estimating an element in a powder sample without synthetic standard samples is described. Allowance is made for the possible effect of the state of combination of the element on relative line intensities, which might interfere with extrapolation from simple addition standards. The method has been tried on a sample of graphite from nodular cast iron, to estimate the Mg content, and has led to the construction of a working curve for the estimation of Mg in graphite in the range 0.1 to 1%. Resume A new spectrochemical method is described for the determination of an unknown element in a powder sample without the aid of standard samples. The method described compensates for possible influence of the form of chemical combination on the relative intensities of the lines measured. The method has been applied to the determination of the Mg content of a graphite sample from a cast iron treated with Mg. The analytical curve for Mg in graphite allowing the determination of Mg from 0.05% to 1.0% can be set up by means of the results obtained.

Dosages des faibles quantités d'un élément dans une poudre sans l'aide d'échantillons standards

A new method of calibration for estimating an element in a powder sample without synthetic standard samples ; allowance is made for the possible effect of the state of combination of the element on relative line intensities, which might interfere with extrapolation from simple addition standards. The method has been tried on a sample of graphite from nodular cast iron, to estimate the Mg content; and has led to the determination of a working curve for the estimation of Mg in graphite in the range 0.1 to 1 %.

The wavelength of the x radiation at a depth in water irradiated by beams of x rays.

A description is given of some measurements of the effective wavelength of the total and primary radiation reaching depths down to 15 cm. in a water phantom irradiated by beams of X rays. The effective wavelengths are determined by measuring the ratio of the ionizations in an “air-equivalent” and an aluminium lined chamber using a modified Kemp comparator, for which a new method of calibration is described. These measurements have been made for four primary radiations of H.V.L.s ranging from 0·49 to 2·4 mm. Cu, and for field areas up to 580 sq. cm. at 50 cm. F.S.D. From these measurements the wavelength of the scattered radiation is deduced and qualitative explanations of the phenomena observed are offered. The significance of the results for the conversion of doses measured in r to doses measured in ergs/gm. are pointed out and some applications to the case of bone are given.

The recruit's heart: Reduplication of the first sound: Heart strain and a new method of calibration

Reduplication after exercise is always of the first, and never of the second, sound, and reduplication of the first sound is an indication of the dilatation of the right ventricle. The right heart is the first to dilate as a result of exercise. Teleroentgenograms and accurate diagrams are given showing not only that the right side of the heart is the first to dilate as a result of exercise, but also the average increase. Teleroentgenograms have also been taken showing that the position of the heart in the thorax varies with posture, and the audibility of murmurs and reduplication in relationship to this is discussed. A detailed description of the pulse rates and blood pressures of boxers before and after contests is given. The effect of strain on the heart and its bearing on the training of the recruit is also described.

Power-circuit instruments for the higher range of audio frequencies

The extending use being made of frequencies from 900 to 12,000 for special purposes such as induction furnaces, etc., introduces new problems in instrument design and calibration. Previous practical a-c instruments were either of the electrodynamic or moving iron types designed for low power frequencies or thermal and rectifier types for audio and radio frequencies, these latter usually being confined to measurements of only current and voltage. The ordinary low frequency electromagnetic instruments have such high coil reactance and losses that they are unsuitable for the higher power frequencies in question without special arrangements, which are described in the paper. Furthermore, the usual calibration methods and standards as previously used for low frequencies are not adequate, and therefore, new methods of calibration were introduced.

Power-Circuit Instruments for the Higher Range of Audio Frequencies

The extending use being made of frequencies from 900 to 12,000 for special purposes such as induction furnaces, etc., introduces new problems in instrument design and calibration. Previous practical a-c instruments were either of the electrodynamic or moving iron types designed for low power frequencies or thermal and rectifier types for audio and radio frequencies, these latter usually being confined to measurements of only current and voltage. The ordinary low frequency electromagnetic instruments have such high coilreactance and losses that they are unsuitable for the higher power frequencies in question without special arrangements, which are described in the paper. Furthermore, the usual calibration methods and standards as previously used for low frequencies are not adequate, and therefore, new methods of calibration were introduced.