Performance improvement using time delays in multivariable controller design

A new controller for linear multivariable ordinary systems is suggested in which distributed delays are included in the feedback loop. A general design approach to obtain this type of controller is suggested. It is shown that the resulting closed-loop system is asymptotically stable under some sufficient conditions. Sufficient conditions are derived under which the disturbance attenuation, the robustness against parameter variations, and the time-delay stability margins are improved by the proposed controller. The state feedback tracking controller and the dual-state observer are obtained by modification of the proposed controller.     

Development of a rational roll pass design for a rolling mill using performance criteria

A new technique is developed to analyze the roll pass design of a section rolling mill. Metal forming nonuniformity and efficiency coefficients, which determine the degree of working of a metal microstructure in rolling of section bars, are used as performance criteria. The system of roll passes intended for the production of a round bar 28 mm in diameter is used as an example to analyze possible deformation schemes and the advantages and disadvantages of each scheme.     

Calculating the size and operating parameters of a slotted filter

The calculation method that yields rational ratios of the thickness of the filter layer and the rate and time of filtration of a slotted filter that provide the target cleaning efficiency of dusted gases in processes at a constant filtration rate has been proposed. The method is based on the concepts of stationary factor and residence time of dusted gas in the filter layer; it considers the efficiency decrease caused by the secondary dust entrainment. It helps to determine the necessary data for the design of a slotted filter that has any target capacity and cleaning efficiency.     

Current flow through metal shunts in ohmic contacts to n +-Si

It is experimentally found that an ohmic contact based on Au-Pt-Ti-Pd-n ⁺-Si metallization is formed due to nanoscale metal shunts containing Si, Au, and Pt in the region of the interface with n ⁺-Si, which appears during heat treatment at T = 450°C for 10 min in a vacuum chamber with a residual pressure of 10^?6 Torr. The high density of shunts adjoining dislocations and other imperfections is confirmed by the temperature dependence of the specific contact resistance ρ _c (T). The density of conductive dislocations, calculated from the temperature dependence of ρ _c is ～5 × 10⁹ cm^?2 which correlates with the density of structural defects, determined by the etch pits after removal of the metallization layers.