Analysis of pure nonferrous and rare metals by atomic emission spectroscopy with photodiode detection

Analytic possibilities of direct determination of impurities in pure nonferrous and rare metals (Ga, In, Cd, Al, Cu, Ni, and Sn) by the arc atomic emission method with application of multichannel atomic emission spectroscopy are studied. The conditions for the performance of the analysis are established. The limits of detection and determination of impurities in studied materials are estimated. The possibility to determine elements at a level of 10^?4?C10^?5 wt % is demonstrated. The accuracy is checked by comparing the obtained results with values of the determined impurities proved by use of state standard reference samples or departmental standard specimens. Improved techniques of arc atomic emission analysis of high purity nonferrous and rare metals are developed. The techniques possess amended metrological characteristics and permit one to considerably reduce the time of carrying out the analysis.     

Detection of Sodium in Highly Pure Graphite via High-Resolution Electrothermal Atomic Absorption Spectrometry with a Continuous Spectrum Source

This study is dedicated to elucidating the analytical abilities of electrothermal atomic absorption spectrometry with a continuous spectrum source (ETAAS-CSS) to detect the presence of sodium in highly pure graphite powder. In order to plot the calibration dependence for sodium detection, a special technique based on argon dilution of the atomic vapor obtained by introducing the aqueous reference solution in the atomizer is applied. The conditions for thermal pretreatment of highly pure graphite powder and atomization of sodium are established, and the sodium detection threshold is evaluated via ETAAS-CSS (2.6 × 10^–4 ng) as well. The validity of the results is confirmed via the sample variation method.     

Low noise SIS mixer for 230 GHz receivers of plateau de bure interferometer

We present a SIS mixer developed for 200 – 250 GHz band receivers of Plateau de Bure Interferometer. We demonstrate the minimum DSB receiver noise of 20 K at 220 GHz. The average receiver noise of 25 K is possible in 200 – 250 GHz range. The receiver conversion gain and output noise instability of 10^?4 on the time scale of 1 minute is comparable with the Shottky receivers performance. The minimum measured SIS mixer noise of about 10 K is close to the quantum limit. The waveguide SIS mixer with a single backshort has two junction array with inductively tuned junctions. The Nb/Al Oxide/Nb SIS junctions are 2.24 µm² each with the Josephson critical current density of 3.2 KA/cm². The thermal properties of the SIS mixer are studied. The mixer band of the low noise operation is in a good agreement with the design requirements.     

Procedure for strength calculation of laminated composite materials under thermomechanical loading conditions

We analyze the procedure for evaluating the load-carrying capacity of structures using complex-reinforced composite materials at the stages of design and checking calculations for strength. A general procedure for predicting the strength characteristics of laminated composite materials is developed that takes into account the temperature effect. The numerical examples of the implementation of this procedure are provided.     

Analysis of disturbances in a leg of pitch-up maneuvering

A complex model of disturbances for a leg of pitch-up maneuvering by a carrier aircraft in launching a launch vehicle was constructed. The model incorporates the atmospheric disturbances (wind gust, jet wind, and density variations), errors in the motion parameters at the point of beginning the maneuver, and the deviation of the initial mass of a launcher aircraft from the design mass. Such a model is required for a priori estimation of the operational requirements (in normal load factor and attack angle), as well as for determination of possible initial errors in the motion of the launch vehicle due to the air launch. We present majority estimates of errors for the most unfavorable combination of disturbances and the results of statistical analysis for the disturbed-motion trajectories by the Monte Carlo method.