Abstract: An assembly for manually rotating a rotor includes a housing enclosing a first shaft and a second shaft accessible through an exterior wall of the housing. The first shaft extends from a first end rotationally coupled to the rotor to a second end selectively engageable with the second shaft. The second shaft includes a thrust plate extending from and rotatable with the second shaft. A spring disposed between the thrust plate and the housing biases the second shaft towards the exterior wall of the housing.

Abstract: A method for detecting and correcting transient faults, the method the steps of comprising obtaining (110) image data from a camera system, and processing (120) image data using a first image signal processor and a second image signal processor, to produce first and second output data. At least one statistical model is generated (130) based on at least the first and second output data and used to identify (140) whether a fault is present in the first output data. A correction value for the portion of image data is generated (150), wherein the correction value is an expected value based on the statistical models, and used to generate (160) updated output data. The updated output data is then outputted (170) to an output device.

Abstract: Aspects of the present invention disclose a method and system for troubleshooting. The method includes identifying data sources providing sensor data, including a first group of measurands. The method further includes processors determining that values of a second group of the measurands of a subset of the sensor data (provided by a given data source, comprising a component set) indicates an anomaly. The method further includes determining a third group of the measurands that are root cause candidates of the anomaly. The measurands of the third group are provided by the component set. The method further includes assigning a set of coefficients to respective measurands. Each coefficient is indicative of a comparison result of each measurand with a measurand of the third group. The method further includes determining, using the sets of coefficients, whether a specific subset of the component set can be identified as an anomaly root cause.

Abstract: A method and system for communicating with IoT devices connected to a vehicle to gather information related to device operation or performance is disclosed. The system makes a copy of at least a portion of the device's non-volatile memory and/or receives IoT device data (e.g., sensor data and/or log files etc.) from an IoT device that recently failed. The system determines which log files and/or sensor data, for example, the IoT device created before and/or after a failure. After gathering this information, the system stores the information, sends it to a storage destination for further analysis and diagnostics to troubleshoot the failure and send a fix or software update to the IoT device. The information can also be placed into secondary storage to comply with regulatory, insurance, or legal purposes.

Abstract: A distress detection system includes a data repository operable to collect sensor data from a monitored system. The distress detection system also includes an analysis system with a processing system operable to access a first parameter of a first system of the monitored system from the data repository and access a second parameter of the first system of the monitored system from the data repository. The processing system is also operable to apply fuzzy reasoning rules to evaluate a combination of the first parameter and the second parameter to determine an in-range interaction with respect to a second system of the monitored system as fuzzy metric data points, classify a component of the second system as being in distress based on comparing the fuzzy metric data points to a limit line, and assert a component distress indicator responsive to classifying the component of the second system as being in distress.

Abstract: Various vehicle systems capable of different operation modes are disclosed. According to one example, the system can include at least one input shaft, at least one output shaft, a plurality of hydraulic devices, and one or more accessories. The plurality of hydraulic devices can be configured to be operable as vane pumps in a retracted vane mode of operation and can be configured to be operable as a hydraulic couplings to couple the at least one input shaft with the at least one output shaft in a vane extended mode of operation. The plurality of hydraulic devices can be simultaneously operable as the hydraulic couplings and the vane pumps. The one or more accessories can be in fluid communication with the plurality of hydraulic devices and can be configured to receive a hydraulic fluid pumped from one or more the plurality of hydraulic devices when operating as the vane pumps.

Abstract: Systems, methods, and apparatus are disclosed for visualizing and simulating operational activity and resources associated with an organization, which may be an airline. One or more data values may be aggregated. The data values may identify operational activity information and resource information associated with the organization. Data structures may be generated based on the aggregated one or more data values. Each of the data structures may represent at least part of an operational activity or resource associated with the organization. A process flow data structure may be generated based on the data structures. The process flow data structure may represent at least some of the operational activity of the organization with respect to time. A report may be generated based on the generated data structures and the generated process flow data structure. The report may identify one or more performance metrics associated with the organization.

Abstract: A fuel system for a gas turbine engine includes, among other things, a plurality of components defining a plurality of localized nodes at distinct locations relative to a fuel flow path, each of the plurality of localized nodes characterized by a distinct set of failure parameters. One or more fuel sensors are configured to measure at least one fuel condition relating to flow through the fuel flow path. A fuel observation assembly is coupled to one or more engine sensors configured to measure at least one engine condition.

Abstract: A method and a system for monitoring an aircraft engine (2), including: acquisition and processing part (11) configured to collect a time signal of the exhaust gas temperature residual margin of the aircraft engine (2), acquisition and processing part (11) configured to smooth the time signal thus forming a first curve representing the temperature residual margin, acquisition and processing part (11) configured to identify decreasing pieces in the first curve, acquisition and processing part (11) configured to construct a second curve by concatenation of the decreasing pieces, the second curve being continuous while being restricted to the decreasing pieces of the first curve, acquisition and processing part (11) configured to construct a prediction model from the second curve to determine at least one failure forecast indicator.

Abstract: A system and computer-implemented method for generating real-time performance advisories for a centrifugal compressor of a fleet of centrifugal compressors are provided. The method includes receiving an actual thermodynamic signature of the compressor, that is unique to the compressor, receiving compressor process parameter values during operation of the compressor, determining, in real-time, an actual performance of the compressor using the compressor process parameter values, determining, in real-time, a predicted performance of the compressor using the received actual thermodynamic signature of the compressor, determining a performance deviation of the compressor using the actual performance and the predicted performance, comparing the performance deviation to a predetermined dynamic threshold range of performance deviation specific to operating speed, and generating a notification to a user using the comparison.

Abstract: A fuel system includes a pump unit having at least a fixed displacement pump supplying pressurized flow. A fuel control assembly receives flow from the pump unit and includes at least one metering valve and at least one throttling valve. A control (bypass valve control) for the fixed displacement pump receives first and second pressure signals indicative of a pressure differential across the throttling valve, or across the metering valve/throttling valve combination, for altering output from the fixed displacement pump in response to the pressure differential. In other embodiments, the pump unit includes a centrifugal pump and a fixed displacement pump that can be fully or partially redundant depending on sizing of the pumps, and the system requirements.

Abstract: An automatic transmission performs a shift-up operation when the accelerator pedal is released from a depression during a vehicle is running. An engine rotation speed immediately after the shift-up operation is predicted on the basis of the engine rotation speed and a gear ratio of the transmission after the shift-up operation. When a fuel recovery is predicted to be performed immediately after the shift-up operation, the fuel recovery is advanced such that it is performed in the inertial phase of the transmission.

Abstract: A system for operating a dual clutch transmission, including launch/creep controller, shift logic, and a clutch control assembly. The shift logic is configured to intercept a torque command including a target clutch torque from the launch/creep controller as it transmits the target clutch torque to the clutch assembly. The shift logic engages a preparation phase that increases torque on an on-coming clutch to a prefill torque. The shift logic then engages a torque phase that transfers torque between the off-going clutch and the on-coming clutch by simultaneously decreasing the off-going clutch torque and increasing the on-coming clutch torque. The off-going clutch and the on-coming clutch remain in a slipping state that maintains the target clutch torque during the transfer.

Abstract: A method of controlling a line pressure in a transmission is provided. Line pressure in a transmission is set to a pressure value including a first term that is proportional to an input torque value. The first term has a coefficient of proportionality that is increased in response to a signal indicating clutch slippage. The input torque value is a measured input torque value in a steady-state condition. The input torque value may be a maximum of the measured input torque value and a driver demand torque value in a transient condition.

Abstract: In order to further improve followability of an actual vehicle speed with respect to a commanded vehicle speed at a starting time point, the present invention is provided with a vehicle speed control part that, a predetermined time before the starting time point that is a time when the commanded vehicle speed rises from zero, sets a clutch position of a vehicle to an initial intermediate position where power is partially transmitted, and at and during a certain period of time after the starting time point, performs clutch feedback control that changes the clutch position depending on a deviation between the actual vehicle speed and the commanded vehicle speed so as to make the actual vehicle speed follow the commanded vehicle speed, wherein the vehicle speed control part sets the initial intermediate position depending on rising commanded acceleration that is a time rate of change at the time when a value of the commanded vehicle speed rises from zero.

Abstract: A vehicle includes an engine, a dry dual-clutch transmission (dDCT) having a pair of input clutches and a gearbox containing oddly- and evenly-numbered gear sets, and a transmission control module (TCM). Application of one of input clutches connects the engine to a corresponding one of the oddly- or evenly-numbered gear sets. The TCM includes feed-forward PID-based control logic, and a torque-to-position (TTP) table for each input clutch. The TCM commands a position of a designated input clutch during a power-on upshift using the feed-forward, PID-based control logic, and selectively adapts the TTP table as a function of an inertia and acceleration value of the engine. The TCM may apply an asymmetrical handoff profile to commanded oncoming and offgoing clutch torques during the torque phase of the upshift. The TCM may also adjust the TTP table as a function of the frequency of use of the input clutches.

Abstract: A system and a method for controlling an aircraft engine starter/generator. The system includes an AGB of fixed gear ratio for coupling mechanically to a turbine shaft of the engine to enable the engine to be started, a gearbox having multiple gear ratios mechanically coupled to a gearwheel of the AGB, a starter/generator mechanically coupled to a gearwheel of the gearbox, and a controller to cause the gear ratio of the gearbox to be changed as a function of the mode of operation of the starter/generator.

Abstract: A gas turbine engine according to an exemplary aspect of the present disclosure includes a windmill pump driven by a spool. A first pump driven by said spool with an air-oil cooler is located downstream of the first pump. A second pump is also driven the spool with an air-air precooler located downstream of the second pump. A method of operating a gas turbine engine during a “windmilling” condition includes driving a windmill pump with a spool during a “windmilling ” condition. A lubricant is communicated to a geared architecture with the windmill pump. A first pump is driven by the spool and an air-oil cooler is located downstream of the first pump.

Abstract: A gas turbine engine includes a first and second pump driven by a spool. An Air-Oil Cooler downstream of the first pump. An air-air precooler is downstream of the second pump, the air-air precooler downstream of the Air-Oil Cooler.

Abstract: A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a fan section including a fan, a geared architecture, a spool which drives the fan through the geared architecture, and at least one component geared to the spool and being operable to control a speed of the spool during a “windmilling” condition. A method of gas turbine engine operations during a “windmilling” condition is also disclosed.

Abstract: A gas turbine engine includes a constant speed transmission driven by a spool. The constant speed transmission drives a first pump and a second pump. In a further non-limiting example, the first pump is driven by a first drive shaft which is driven by the constant speed transmission and the second pump is driven by a second drive shaft which is driven by the first shaft through a gearbox to provide a constant speed ratio between the first shaft and the second shaft.

Abstract: An engine system for starting a gas turbine engine is provided. The system includes a starter generator coupled to the gas turbine engine and configured to provide torque to the gas turbine engine and a controller coupled to the starter generator and configured to provide a command signal to the starter generator. The starter generator provides the torque to the gas turbine engine based on the command signal, and the controller is configured to command the starter generator at a dwell speed until ignition.

Abstract: Certain embodiments of the invention may include systems and methods for controlling an integrated drive train. According to an example embodiment of the invention, a method for controlling a gas turbine drive train includes measuring speed associated with the drive train, controlling fuel flow to a gas turbine based at least in part on a speed command and the measured speed, controlling one or more guide vanes associated with a torque converter based at least in part on the speed command and an expected power output of the torque converter, and selectively coordinating respective torque contributions from the torque converter and the gas turbine.

Abstract: Certain embodiments of the invention may include systems and methods for controlling an integrated drive train. According to an example embodiment of the invention, a method for controlling a gas turbine drive train includes measuring speed associated with the drive train, controlling fuel flow to a gas turbine based at least in part on a speed command and the measured speed, controlling one or more guide vanes associated with a torque converter based at least in part on the speed command and an expected power output of the torque converter, and selectively coordinating respective torque contributions from the torque converter and the gas turbine.

Abstract: Interruption in supervisory position control signals can cause problems with respect to actuators which upon loss of such control signals for the actuator will generally slew to a fixed idle position. In such circumstances a machine such as a gas turbine engine in which an actuator is associated will not sustain performance even though there is continued local power supply to the actuator. By utilizing a local controller which stores actuator response profiles for certain machine status stages through perturbation or marginal activation of the actuator an appropriate actuator response profile can be chosen and therefore sustaining control signals presented to the actuator to maintain machine operation.

Abstract: Embodiments of the invention can provide systems and methods for using a combustion dynamics tuning algorithm with a multi-can combustor. According to one embodiment of the invention, a method for controlling a gas turbine engine with an engine model can be implemented for an engine comprising multiple cans. The method can include obtaining operating frequency information associated with multiple cans of the engine. In addition, the method can include determining variation between operating frequency information of at least two cans. Furthermore, the method can include determining a median value based at least in part on the variation. Moreover, the method can include determining whether the median value exceeds at least one operating threshold. The method can also include implementing at least one engine control action to modify at least one of the operating frequencies if at least one operating threshold is exceeded.

Abstract: In a system for monitoring an output of a sensor for detecting an operating state of a gas turbine engine by comparing a value of an output of the sensor with a prescribed reference value, a calibration map for converting the output of the sensor into a variable that is normally used for controlling the engine is used for defining the reference value for determining the state of the sensor. Thereby, a fault of a sensor can be detected both accurately and promptly by using the existing resource without unduly complicating the control program. It is particularly desirable to monitor the output of the sensor by taking into account the current operating condition of the engine to improve the reliability in detecting a fault in the sensor.

Abstract: In a process for protection of a gas turbine (1) from damage caused by pressure pulsations (P), pressure pulsations (P) occurring during the operation of the gas turbine (1) are measured, from the measured pressure pulsations (P), a pulsation-time signal (PZS) is generated, the pulsation-time signal (PZS) is transformed into a pulsation-frequency signal (PFS), from the pulsation-frequency signal (PFS), a pulsation level (PL) is determined for at least one specified monitoring frequency band (12), the pulsation level (PL) is monitored for the occurrence of at least one specified trigger condition, and, when the at least one trigger condition occurs, a specified protective action (16) is carried out.

Abstract: A gas turbine engine is provided that includes a gearbox operable to selectively couple a relatively high pressure spool shaft to a relatively low pressure spool shaft. In one form the gearbox includes a cone clutch that engages a male member of the cone clutch to a female member of the cone clutch during an engine start of the gas turbine engine. A relatively high pressure of a working fluid can be used to bring the male member and the female member together. A spring can also be used to urge the male member and the female member apart when the working fluid is at a relatively low pressure.

Abstract: An open-rotor gas turbine engine comprising a starter/generator, a first spool and a second spool, the second spool is of a lower pressure than the first spool; wherein the starter/generator is connected to the first and second spools via first and second clutches respectively. The method of operating the open-rotor engine comprises the step of supplying power to the starter/generator to drive the first spool via the first clutch to start the engine and, once the engine is self-propelling, a step of driving the starter/generator from the second spool via the second clutch to generate electricity.

Abstract: A method for determining when in the course of a shift event an on-coming clutch gains torque capacity is provided. The method includes closed-loop controlling an off-going clutch to maintain a predetermined slip threshold by generating an off-going clutch pressure command, causing the on-coming clutch to engage during the closed loop control of the off-going clutch, generating a first derivative with respect to time of the off-going clutch pressure command, and using the first derivative to determine when the on-coming clutch gained torque capacity. A neural network method is preferably employed in analyzing the first derivative to locate a transition in the rate of commanded pressure indicative of off-going clutch release. A corresponding apparatus is also provided.

Abstract: A system and method implements improved machine performance, most preferably for gas turbine engines. The system and method implement a control law that receives sensed operational parameter feedback signals. For each sensed engine operational parameter, the feedback signals that are supplied to the control law selectively comprise the sensor signal representative of the engine operational parameter, if the sensor signal is valid, or an observer estimate of the sensed engine operational parameter, if the sensor signal is invalid.

Abstract: The present invention relates to launch control of a vehicle having an automated manual transmission and an automated clutch selectively engaging an output of an engine to an input of the transmission. When a request for vehicle launch is detected, an output speed of the automated clutch and a desired clutch output torque are obtained. The automated clutch is partially engaged to allow for slip between an input to the clutch and an output from the clutch, and a desired amount of the slip between the input to the clutch and the output from the clutch is determined. A desired engine speed is calculated based on the desired amount of slip, with the engine torque automatically adjusted to obtain the desired engine speed.

Abstract: The present invention is directed to a method for utilizing CO2 waste comprising recovering carbon dioxide from an industrial process that produces a waste stream comprising carbon dioxide in an amount greater than an amount of carbon dioxide present in starting materials for the industrial process. The method further includes producing hydrogen using a renewable energy resource and producing a hydrocarbon material utilizing the produced hydrogen and the recovered carbon dioxide.

Abstract: A method for determining how well configurations for a gas turbine propulsion system attain selected acoustic wave energy emissions criteria based on acquiring a plurality of acoustic frequency spectra representations of a noise representation therefor over an operating duration. Relative peaks in the acoustic frequency spectra representations are then located and the forms of at least one of those peaks is altered with respect to acoustic frequency in manners substantially matching acoustic wave energy emissions changes corresponding to configuration changes in gas turbine propulsion systems which are then evaluated to provide an operating parameter noise value. One of those operating parameter noise values that best meets the selected acoustic wave energy emissions criteria is used to aid in determining corresponding configurations changes to thereby better meet those criteria.

Abstract: A method of estimating quality parameters for a plurality of engine components of a gas turbine engine is provided. The engine components have at least one sensor responsive to the engine component operation. The method includes providing an engine model having virtual sensor values and quality parameters corresponding to the plurality of sensors of the engine components; comparing the virtual sensor values to actual sensor values of the plurality of sensors of the engine components to determine the difference between the actual and virtual sensor values; amplifying the difference by a predetermined gain; generating a plurality of quality parameter deltas in response to the sensed difference; iteratively updating the embedded engine model by inputting a predetermined portion of the generated quality parameter deltas into the embedded engine model; adjusting the embedded engine model for engine operating conditions; and recalculating the virtual sensor values.

Abstract: A system and method implements improved machine performance, most preferably for gas turbine engines. The system and method implement a control law that receives sensed operational parameter feedback signals. For each sensed engine operational parameter, the feedback signals that are supplied to the control law selectively comprise the sensor signal representative of the engine operational parameter, if the sensor signal is valid, or an observer estimate of the sensed engine operational parameter, if the sensor signal is invalid.

Abstract: A system employing a torque converter and a synchronizing motor to start up a large rotational driver/load combination. The torque converter is employed to increase the rotational speed of the load to the maximum speed permitted by the torque converter. The synchronizing motor is then employed to further increase the rotational speed of the load to substantially match the rotational speed of the driver.

Abstract: A turbine overspeed control system for use with a gas turbine engine of a gas turbine electrical powerplant. The overspeed control system preferably comprises a first and second overspeed control subsystem. When an overspeed condition of the gas turbine engine is detected, the first overspeed control subsystem acts to remove air from a combustion section of the engine, while the second overspeed control subsystem operates to alter the angle at which an incoming flow of air is supplied to a compressor turbine located therein. The result of operating the first and/or second overspeed control subsystem is a reduction in the speed of the gas turbine engine that is much more rapid than can be accomplished by simply shutting off a fuel supply thereto.

Abstract: Method for detecting faults in a device comprising the steps of receiving a plurality of performance parameters, applying the plurality of performance parameters to a first model to produce a plurality of estimated performance parameters, applying the plurality of performance parameters to a second model to produce a plurality of estimated device parameters, computing a plurality of residuals from the plurality of estimated device parameters, computing a plurality of distance measuring from the plurality of residuals, detecting at least one parameter deviation using the plurality of residuals and the plurality of estimated performance parameters, and setting at least one detection flag if the detected at least one parameter deviation is persistent.

Abstract: A method for determining how well configurations for a gas turbine propulsion system attain selected acoustic wave energy emissions criteria based on acquiring a plurality of acoustic frequency spectra representations of a noise representation therefor over an operating duration. Relative peaks in the acoustic frequency spectra representations are then located and the forms of at least one of those peaks is altered with respect to acoustic frequency in manners substantially matching acoustic wave energy emissions changes corresponding to configuration changes in gas turbine propulsion systems which are then evaluated to provide an operating parameter noise value. One of those operating parameter noise values that best meets the selected acoustic wave energy emissions criteria is used to aid in determining corresponding configurations changes to thereby better meet those criteria.

Abstract: An on-engine data storage device for a gas turbine engine includes a housing, an interface device, and a memory device. The interface device can communicate with a peripheral device. The memory device is mounted within the housing and is operable to store engine data related to the gas turbine engine.

Abstract: A system and method is provided for fault detection in a turbine engine. The fault detection system and method uses discrete event system modeling to provide improved fault diagnosis and prognosis. The fault detection system and method receives sensor taken at multiple dynamic events occurring in different time windows. An event determination mechanism evaluates the received sensor data to determine if specified events have occurred. Indications of the occurrence of specified events are then passed to a discrete event system model. The discrete event system model analyzes the timing and sequencing of the event occurrences to determine if a fault has occurred. This method does not require a detailed modeling of the system, and thus can be applied to complex systems such as turbine engines.

Abstract: A method for monitoring engine performance includes sampling exhaust gas temperature associated with a turbine engine over an interval of operational time of the turbine engine. The method further includes applying a first test to identify statistical outliers on the sampled exhaust gas temperature data and removing identified statistical outliers from the sampled exhaust gas temperature data. Subsequently, the method includes applying a second test to identify step changes in slope of the exhaust gas temperature data and dividing the interval of operational time into one or more segments based upon the identified step changes. Finally, the method includes determining a slope for each segment and combining the segments to obtain a rate of performance deterioration of the turbine engine.

Abstract: A method for determining a target exhaust temperature for a gas turbine including: determining a target exhaust temperature based on a compressor pressure condition; determining a temperature adjustment to the target exhaust temperature based on at least one parameter of a group of parameters consisting of specific humidity, compressor inlet pressure loss and turbine exhaust back pressure; and adjusting the target exhaust temperature by applying the temperature adjustment.

Abstract: A turbine valve control system is provided. The turbine valve control system includes a variable flow metering device, a first sensor, a second sensor, a third sensor, a fourth sensor, memory, and processing circuitry. The variable flow metering device is capable of meeting a plurality of predetermined mass flow rates by varying positioning of the flow metering device. The processing circuitry is configured to receive the signals, determine whether the flow is subsonic or sonic, and implement a corresponding one of the first and second computer program codes to calculate a combined coefficient of discharge times area that will generate a desired mass flow rate for the flow metering device. A method is also provided.

Abstract: A method and system for designing an impingement film floatwall panel system for a combustion chamber for a gas turbine engine comprising the steps of creating an impingement film floatwall panel knowledge base of information. The knowledge base has a plurality of design rule signals with respect to a corresponding plurality of parameter signals of associated elements of impingement film floatwall panels for a combustion chamber, wherein the knowledge base comprises at least one data value signal for each one of the plurality of design rule signals. The steps also include entering a desired data value signal for a selected one of the plurality of parameter signals of an associated element of the impingement film floatwall panels and comparing the entered desired data value signal for the selected one of the plurality of parameters with the corresponding at least one data value signal in the knowledge base for the corresponding one of the plurality of design rule signals.

Abstract: A microprocessor-based control system for a gas turbine electrical powerplant. the microprocessor-based control system controls the startup, operation, and shutdown of the gas turbine electric powerplant. The microprocessor-based control system of the present invention dispenses with the need to utilize relays, timers, or other control hardware. Rather, the microprocessor-based control system employs software that replaces the control hardware, and directly reads the inputs, calculates the control actions, and writes the outputs. The microprocessor-based control system is also in electrical communication with an overspeed control system, provided to ensure that a runaway condition of the gas turbine engine does not occur should the gas turbine engine become disconnected from the speed reducer (gearbox) or generator. Sensors are used to monitor multiple operating conditions of the powerplant.

Abstract: A method of performing diagnostics on a system comprises receiving a plurality of measurement parameters, each corresponding to one of a plurality of parameters at a time k, forming a deviation vector from the plurality of measurement parameters, calculating an initial deviation vector from an initial fault vector, calculating a multiple fault isolation deviation vector using the initial deviation vector and the deviation vector, determining if an event is in progress using the multiple fault isolation deviation vector, performing statistical data validity to set a present inhibit flag and a past inhibit flag, and performing module performance analysis according to the present inhibit flag and the past inhibit flag.

Abstract: A system is disclosed for use in assembling a plurality of rotatable elements in the assembly of a turbine engine. The system includes an initialization unit, a measurement unit, and a processing unit. The initialization unit is for entering initialization data into a database. The initialization data includes a first set of initialization data that is representative of characteristics of a first rotatable element, and a second set of initialization data that is representative of characteristics of a second rotatable element. The measurement unit is for permitting a user to enter measured data including a first set of measured data characteristic of measured features of the first rotatable element, and a second set of measured data characteristic of measured features of the second rotatable element.