Solution of the stochastic H ∞-optimization problem for discrete time linear systems under parametric uncertainty

The stochastic H _∞-optimization problem for a linear discrete time system with uncertain parameters is formulated and solved. The system operates in the presence of Gaussian random disturbances. The original problem with parametric uncertainty is reduced to the stochastic H _∞-optimization problem without uncertainty and having one extra input, which is essentially the mixed H ₂/H _∞-optimization problem. In a sense, the problem considered in this paper incorporates the classical H ₂/H _∞-and H _∞-optimization problems as limiting cases.     

NIST 0:45 reflectometer

The NIST 0:45 reflectometer measures the spectral reflectance factor at an influx angle of 0° and an efflux angle of 45° of colored, nonfluorescent specimens at room temperature, with widths ranging from 3 to 10 cm and heights from 3 to 20 cm and with an uncertainty of less than 0.5 in color difference units. Published in 2008 by John Wiley & Sons, Inc. Col Res Appl, 33, 94–99, 2008     

Features of high-density industrial ceramics technology. Selection of modifying additives

The effect of modifying additives on sintering, microstructure control, and the properties of ceramics was demonstrated. The types of additives with a different type of reaction with the crystal lattice of the basic oxide in sintering were examined. Oxides that form solid solutions are the most effective additives that significantly affect sintering and microstructure formation processes.     

Removal of acidic impurities from gases by absorption using monoethanolamine: A review

Recent research on absorbent applications of monoethanolamine and its solutions in water and other organic compounds is reviewed.     

Uncertainty analysis for the NIST 0:45 Reflectometer

Sets of color tiles are available from the National Institute of Standards and Technology calibrated using the NIST 0:45 Reflectometer. The uncertainties associated with the measured values for the color tiles are an indispensable component of the calibration report that accompanies these tiles. A systematic, analytical approach developed previously was applied to the particular case of the reference instrument and color tile set, taking into account the operation and characteristics of the instrument and the spectral properties of the set. The primary sources of uncertainty were identified, and the resulting uncertainties in the color space values L*, a*, and b* were determined. In general, the uncertainties are lowest for those color tiles whose reflectance factors are nearly constant with wavelength. Published in 2008 by John Wiley & Sons, Inc. Col Res Appl, 33, 100–107, 2008     

High density technical ceramics: Technology and preparation of green articles for sintering

It is shown that the degree of aggregation of powders and the properties of aggregates (size, strength, porosity) affect the degree of sintering and the microstructure characteristics of the ceramic fabricated. The conditions for obtaining low-aggregation powder and methods for de-aggregating powder are examined. The requirements which powders must satisfy in order to obtain compacts with a uniform pore size and uniform sintering over the volume of the articles are formulated.     

Relative yield of delayed neutrons and half-life of their precursor nuclei with fissioning of 239Pu by 14.2–17.9 MeV neutrons

The energy dependence of the relative yield of delayed neutrons and of half-lives of their precursor nuclei with fissioning ²³⁹Pu by 14.2–17.9 MeV neutrons is measured. The data obtained are analyzed in terms of the average half-life 〈T〉 of the precursor nuclei of the delayed neutrons. It is shown that the observed growth of 〈T〉 with increasing primary neutron energy in the energy range studied is due predominately to opening of the channels for the emission fission of nuclei. Comparing the data on the average half-life of the precursor nuclei of delayed neutrons obtained in the present work with those obtained by other authors showed that the anomalously high values of 〈T〉 are due to methodological features of the experiment which are related with the properties of the reaction T(d, n)⁴He used as a neutron source on electrostatic charged-particle accelerators. The data obtained are of great value for developing instrumentational nondestructive means for determining the nuclide composition of nuclear fuel based on the detection of delayed neutrons. __________ Translated from Atomnaya énergiya, Vol. 101, No. 6, pp. 441–444, December, 2006.     

CRITICAL POINTS IN THE SOLIDIFICATION OF A PURE MATERIAL

Patterns in the solidification of a pure material are dealt with in this article. Results, deduced from a simple model based on heat conduction in the two phases and the effect of surface tension on the equilibrium temperature at the moving front, present a guide for experimental work. By introducing far-field conditions imitating what can be achieved in an experiment, we explain how the depths of the phases and the width of the container influence the patterns that can be seen if one advances the control variable to the critical point and then just beyond. Our new result is the existence of a third critical point. It occurs at small wave numbers and it is independent of surface tension. It appears because we take the depths of the phases into account. These depths are input values that offer the possibility of controlling crest-to-trough conduction, stabilizing in the solid, destabilizing in the liquid. The new critical point, and the patterns attending its appearance, can be found in cells of easily attainable widths.