Abstract:
Time-of-flight measurements calculate the absolute caliper of a moving film independent of the film's index of refraction. A reflective fiber coupled terahertz gauge is mounted co-axially with a temperature stabilized Z-sensor positioned within a scanner head. The terahertz gauge monitors four reflections: (1) the reflection from a sensor window, (2, 3) the reflections from the top and bottom surfaces of the sheet product being measured, and (4) the reflection from a reflector that is placed behind the sheet. The Z-sensor monitors the distance between the reflector and the senor window. The terahertz reflection delays together with the Z distance measurements allow extraction of the caliper. Since the time delay due to the sheet is a function of thickness and index of refraction, the basis weight of the sheet can be determined by using a calibration of the sensor relating basis weight of the product to time delay.
Abstract:
Near infrared moisture sensors using stable holmium oxide glass calibration standards that simulate different moistures levels in paper obviates problems associated with glass encased paper samples. Holmium oxide glass has a strong absorption at 1.93 microns which is close to absorption by paper. Standards can have varying thicknesses to simulate different moisture levels. Didymium glass can also be used with holmium oxide glass. The moisture sensor operates at reference and measurement infrared regions of 1.94 microns and 1.8 microns, respectively.
Abstract:
A system includes at least one common support (202, 208a, 208b) configured to span at least a width of a web (108) of material in a manufacturing or processing system (100). The system also includes multiple sensor heads (204a, 204b, 204c) each configured to move independently along at least part of the at least one common support. The sensor heads can be configured to move simultaneously along the at least one common support, and at least one controller (104, 310a, 310b) can be configured to control movement of the sensor heads so that the sensor heads do not contact one another. Each sensor head could include one or more sensors (304a, 304b) configured to measure one or more characteristics of the web. Different sensor heads could include different types of sensors. The sensor heads can be configured to move in non-overlapping patterns over or under the web. Different sensor heads can be configured to move at different speeds.
Abstract:
Robust terahertz time-domain spectrometer has a reflective surface arrangement that renders the sensor insensitive to x or y displacement. The apparatus includes: (a) first scanner head; (b) a first reflective surface; (c) emitter; (d) beam splitter to yield reference radiation pulses and sample radiation pulses; (e) first reflector to reflect sample radiation pulses that have been transmitted through the sample to generate reflected sample radiation pulses that are directed towards a web; (f) second reflector that reflects the reference radiation pulses to generate reflected reference radiation pulses that are directed towards the beam splitter which in turn transmits a portion of the reflected references radiation pulses towards the web; and (g) a detector that receives (i) the reflected sample radiation pulses that have interacted with the sample a plurality of times and (ii) reflected reference radiation pulses that have interacted with the sample a plurality of times.
Abstract:
A method includes acquiring (601) process data collected in an industrial process control and automation system (100). The method also includes reducing (603) a dimension space of the process data by combining two or more parameters (405, 410, 415) of the process data or examining a frequency response of the process 5 data. The method further includes determining (605) a change in a process based on a change in the process data in the reduced dimension space. The method also includes outputting (607) a result based on the determined change in the process.
Abstract:
A method includes moving (404) a first sensor assembly (108, 110) to a plurality of cross direction positions (500, 600) relative to a second sensor assembly (110, 108), where the first and second sensor assemblies are configured to move in the cross direction relative to a web (102) of material. The method also includes, for each of the plurality of cross direction positions, determining (406) a sensor value associated with a sensor source (212a, 212b) disposed at the second sensor assembly as measured by a sensor receiver (212b, 212a) disposed at the first sensor assembly. The method further includes determining (410) a starting alignment position (500a, 600a) of the first sensor assembly to be a first cross direction position where a difference between the sensor value at the first cross direction position and a corresponding sensor value at one or more adjacent cross direction positions is a minimum.
Abstract:
A method includes obtaining (902) a model (304) associated with a model-based controller (104, 306) in an industrial process (100, 302) having multiple actuator arrays (114, 116, 118, 120) and performing (914) temporal tuning of the controller. The temporal tuning includes adjusting one or more parameters of a multivariable filter (308) used to smooth reference trajectories of actuator profiles of the actuator arrays. The temporal tuning could also include obtaining (904) one or more uncertainty specifications for one or more temporal parameters of the model, obtaining (916) one or more overshoot limits for the actuator profiles, identifying (918) a minimum bound for profile trajectory tuning parameters, and identifying (920) one or more of the profile trajectory tuning parameters that minimize one or more measurement settling times without exceeding the one or more overshoot limits. The controller could be configured to use the adjusted parameter(s) during control of the industrial process such that the adjusting of the parameter(s) alters operation of the controller and the industrial process.
Abstract:
A method includes obtaining (902) one or more models (304) associated with a model-based controller (104, 306) in an industrial process (100, 302) having multiple actuator arrays (114, 116, 118, 120) and performing (906) spatial tuning of the controller. The spatial tuning includes identifying weighting matrices that suppress one or more frequency components in actuator profiles of the actuator arrays. The spatial tuning could also include finding (908) a worst-case cutoff frequency over all output channels for each process input, designing (910) the weighting matrices to penalize higher-frequency actuator variability based on the model(s) and the cutoff frequencies, and finding (912) a multiplier for a spatial frequency weighted actuator variability term in a function that guarantees robust spatial stability. The controller could be configured to use a function during control of the industrial process, where a change to one or more terms of the function alters operation of the controller and the industrial process and at least one term is based on the weighting matrices.
Abstract:
A method includes executing (302) a control algorithm for an industrial process using a controller objective function, where the industrial process is associated with at least one controlled variable. The method also includes executing (306) an optimization algorithm for the industrial process using an extended version of the controller objective function. The extended version of the controller objective function includes one or more additional terms added to the controller objective function, and one or more results of the optimization algorithm are provided to the control algorithm. The method further includes, based on tracking errors associated with the at least one controlled variable, adjusting (314) at least one adaptive weight parameter in the extended version of the controller objective function. The at least one adaptive weight parameter is associated with at least one of the one or more additional terms.
Abstract:
Continuous on-line thin film measurements employ a sensor having a spectrometer for interferometric measurements and a stack of single channel detectors for adsorption measurements. The stack is separated from the spectrometer, which analyzes radiation that emerges (transmitted pass or reflected from) the film, whereas the stack analyzes radiation that has passed through the film multiple times. The spectrometer is (i) positioned directly opposite the source of radiation so that it detects transmitted radiation or (ii) disposed on the same side of the film as is the source of radiation so that the spectrometer detects radiation that is specularly reflected from the film. The sensor includes a broadband radiation source emitting visible to far infrared light which propagates through a measurement cell defined by reflective surfaces exhibiting Lambertian-type scattering. The sensor is capable of measuring thin plastic films with thicknesses down to 1 micron or less.