A chemical system for an operation to make an alkylene oxide, the operation exhibiting steady-state gain inversion; the system comprising: a reactor feed stream comprising a combination of: an olefin feed stream which includes saturated hydrocarbons; an oxygen feed; and a gas phase promoter feed; a reactor configured to receive the reactor feed stream and produce an outlet stream including an alkylene oxide product to form a process; and a control device configured to control the process, wherein the control device receives inputs indicative of an operational parameter and output variables and, in response to the inputs and output variables, provides a steady-state manipulated input configured to control or optimize the process, the control device including: an input disturbance model based on using the steady-state manipulated input as a custom output measurement to determine unmeasured disturbances, a state estimator configured to utilize the custom output measurement to estimate the unmeasured disturbances entering the process and thereby predict a change in the process based on a characterization of the process by the model, a non-linear steady-state target calculator configured to determine the steady-state manipulated input for the process based on the characterization of the process as calculated by the model, and a regulator configured to provide a signal for adjustment of one or more inputs based on the steady-state manipulated input and associated output variables, wherein the regulator determines a change in the manipulated input to optimize the output variable based on an observation of a gain inversion over a settling time of the control device if the manipulated input to maximize the variable output is within an operational threshold, one or more measured disturbances are steady as based on statistical criteria, the manipulated input is steady or moving towards an optimum steady-state manipulated input, and a new optimum optimized manipulated input is observed after a settling time of the control device. a reactor feed stream comprising a combination of: an olefin feed stream which includes saturated hydrocarbons; an oxygen feed; and a gas phase promoter feed; an olefin feed stream which includes saturated hydrocarbons; an oxygen feed; and a gas phase promoter feed; a reactor configured to receive the reactor feed stream and produce an outlet stream including an alkylene oxide product to form a process; and a control device configured to control the process, wherein the control device receives inputs indicative of an operational parameter and output variables and, in response to the inputs and output variables, provides a steady-state manipulated input configured to control or optimize the process, the control device including: an input disturbance model based on using the steady-state manipulated input as a custom output measurement to determine unmeasured disturbances, a state estimator configured to utilize the custom output measurement to estimate the unmeasured disturbances entering the process and thereby predict a change in the process based on a characterization of the process by the model, a non-linear steady-state target calculator configured to determine the steady-state manipulated input for the process based on the characterization of the process as calculated by the model, and a regulator configured to provide a signal for adjustment of one or more inputs based on the steady-state manipulated input and associated output variables, wherein the regulator determines a change in the manipulated input to optimize the output variable based on an observation of a gain inversion over a settling time of the control device if the manipulated input to maximize the variable output is within an operational threshold, one or more measured disturbances are steady as based on statistical criteria, the manipulated input is steady or moving towards an optimum steady-state manipulated input, and a new optimum optimized manipulated input is observed after a settling time of the control device. an input disturbance model based on using the steady-state manipulated input as a custom output measurement to determine unmeasured disturbances, a state estimator configured to utilize the custom output measurement to estimate the unmeasured disturbances entering the process and thereby predict a change in the process based on a characterization of the process by the model, a non-linear steady-state target calculator configured to determine the steady-state manipulated input for the process based on the characterization of the process as calculated by the model, and a regulator configured to provide a signal for adjustment of one or more inputs based on the steady-state manipulated input and associated output variables, wherein the regulator determines a change in the manipulated input to optimize the output variable based on an observation of a gain inversion over a settling time of the control device if the manipulated input to maximize the variable output is within an operational threshold, one or more measured disturbances are steady as based on statistical criteria, the manipulated input is steady or moving towards an optimum steady-state manipulated input, and a new optimum optimized manipulated input is observed after a settling time of the control device.