Model reduction for robust control: A schur relative error method

A numerically robust relative error method for state-space model order reduction is described. Our algorithm is based on Desai's balanced stochastic truncation technique for which Green has obtained an L^∞ relative error bound. However, unlike previous methods, our Schur method completely circumvents the numerically delicate initial step of obtaining a minimal balanced stochastic realization of the power spectrum matrix G(s)G^T(?s).     

Variometric meters of rate of pressure variations (Review of US Patents)

Conclusions The simple design of a variometer as compared with other instruments and devices used for measuring the rate of pressure changes determines the promising possibilities of its application for measuring adequately large rates of change, that is, sufficiently high vertical velocities in ascent or descent. However, the considerable time constants of a variometer, which attain 4–8 sec, constitute its essential drawback.Variometers can also be used for measuring small rates of pressure changes. However, in that case it becomes necessary to measure small pressure differences and, therefore, it is essential to increase the size of the elastic element and the volume of the chamber, thus leading to a considerable rise in the instrument's time constant. Moreover, the designing of variometers for measuring small rates of pressure changes leads to a sharp rise in their dimensions and weight.The existing methods of compensating the retardation error of variometers as well as their temperature and height errors provide satisfactory results, although they do not completely eliminate these errors and, moreover, in the majority of cases they considerably complicate the design of variometers.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 31–34, April, 1969.     

Ultrasonic defectoscopy of joints in sectional monolithic hydraulic structures

Conclusions These experiments make it possible to recommend the ultrasonic impulse technique in checking and defectoscopy of connecting joints in sectional monolithic hydraulic structures. This technique yields industrially reliable results without disturbing the continuity of the structures. Ultrasonic defectoscopy of joints was adopted as a principal mass-application checking method in construction of the Saratov Hydroelectric Station. Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 19–23, July, 1968.