Abstract: In a distillation column, which for control purposes cannot tolerate the inherent dead time between analysis of consecutive samples in chromatograph analyzers, the chromatograph output is frequently corrected by inferring a dynamic correction based on the temperature change of a selected tray in the column. The dynamic correction applied to the distillation analyzer essentially eliminates the inherent dead time for obtaining a chromatograph analysis, and accordingly increased the rapidity of response of the column controls which rely on chromatograph analysis.

Abstract: In a fractional distillation process which performs a binary or limited multicomponent separation, and in which it is desired to maintain composition set points for dual product streams, a computer is programmed for applying model based control. Multivariable, noninteracting control of the distillation process is achieved by utilizing a nonlinear model, which calculates process vapor and distillate flow rates required to maintain product set points. The model, which applies tray-to-tray calculation essentially derived from a McCabe-Thiele analysis, is periodically updated by adjusting tray efficiency based on steady state composition measurements to keep the model in pace with changing process conditions.

Abstract: In a fractional distillation process which performs a binary or limited multicomponent separation, and in which it is desired to maintain composition set points for dual product streams, a computer is programmed for applying model based control. Multivariable, noninteracting control of the distillation process is achieved by utilizing a nonlinear model, which calculates process vapor and distillate flow rates required to maintain product set points. The model, which applies tray-to-tray calculation essentially derived from a McCabe-Thiele analysis, is periodically updated by adjusting tray efficiency based on steady state composition measurements to keep the model in pace with changing process conditions.

Abstract: A system for transmitting digital data employs an angle modulated carrier signal having constant amplitude and a limited spectrum. The system comprises an offset quadrature phase shift key (QPSK) modulator with a "tracking filter" phaselocked loop at the output of the QPSK modulator. The phaselocked loop has a voltage controlled oscillator which produces a constant amplitude carrier signal at the output of the loop, and also has a low pass loop filter which reduces the spectrum of the phase modulated carrier signal. Additional spectrum shaping is obtained by connecting L-R-C circuits to the low pass loop filter to eliminate predetermined frequency components from the output of the loop.

Abstract: Each of a plurality of programmable master devices having access to a data communication link is assigned a unique address based on the priority of that master device. Each of the plurality of programmable master devices is also interfaced to an access channel. Each of the plurality of programmable master devices can try to gain control of the data link by activating the access channel. The unique address of each programmable master device provides a means by which the highest priority master devices can lock out the lower priority master devices so as to prevent simultaneous transmission on the data link and also prevent loss of high priority data even when a lower priority programmable master device is the device which has activated the access channel.