Abstract: A braking device for a vehicle comprises a main brake cylinder, which provides, in response to the actuation thereof, an operating brake pressure in at least one operating brake circuit for the actuation of an operating brake. A hydraulic fluid pressure intake is connected to a hydraulic circuit, which contains a hydraulic fluid having a built-up hydraulic circuit pressure. Through the hydraulic fluid pressure intake, the hydraulic fluid is provided at the hydraulic circuit pressure. The braking device further comprises a valve device, which actively controls a main brake cylinder actuation pressure and/or a parking brake release pressure by means of the hydraulic fluid that is provided. The main brake cylinder is actuated by means of the main brake cylinder actuation pressure for an active brake engagement. Alternatively or additionally, a parking brake is hydraulically released by means of the parking brake release pressure.

Abstract: Active acoustic pyrometry-based gas flow temperature measurement, such as for monitoring of gas turbine combustors, including industrial gas turbine (IGT) combustors is incorporated into the combustion monitoring and control system by addition of an acoustic transmitter or acoustic transceiver that transmits a sound wave in a line-of-sight with a plurality of acoustic sensors, such as dynamic pressure sensors. For temperature measurement, in some embodiments sound transmission time-of-flight that is directed generally transverse the gas flow path is measured by the controller and correlated with gas flow temperature along the line-of-sight. In other embodiments line-of-sight correlated gas flow temperatures in up and down stream planar paths are interpolated. In an integrated thermoacoustic pressure-based sensor and monitoring/control system embodiment, the controller determines absolute active path temperatures with acoustic transmission and time-of-flight analysis techniques.

Abstract: An acoustic signal traversing a hot gas is sampled at a source and a receiver and is represented in overlapping windows that maximize useable signal content. Samples in each window are processed to represented in different sparsified bins in the frequency domain. Determining a signal delay between the source and the receiver from a summation of maximum smoothed coherence transform cross-correlation values of different data windows wherein a sparseness of a mean smoothed coherence transform cross-correlation of windows is maximized. Determining a set of delay times wherein outliers are deleted to estimate a time of flight from which a temperature of the hot gas is calculated.

Abstract: An apparatus for controlling operation of a gas turbine engine including at least one acoustic transmitter/receiver device located on a flow path boundary structure. The acoustic transmitter/receiver device includes an elongated sound passage defined by a surface of revolution having opposing first and second ends and a central axis extending between the first and second ends, an acoustic sound source located at the first end, and an acoustic receiver located within the sound passage between the first and second ends. The boundary structure includes an opening extending from outside the boundary structure to the flow path, and the second end of the surface of revolution is affixed to the boundary structure at the opening for passage of acoustic signals between the sound passage and the flow path.

Abstract: A method for determining waveguide temperature for at least one waveguide of a transceiver utilized for generating a temperature map. The transceiver generates an acoustic signal that travels through a measurement space in a hot gas flow path defined by a wall such as in a combustor. The method includes calculating a total time of flight for the acoustic signal and subtracting a waveguide travel time from the total time of flight to obtain a measurement space travel time. A temperature map is calculated based on the measurement space travel time. An estimated wall temperature is obtained from the temperature map. An estimated waveguide temperature is then calculated based on the estimated wall temperature wherein the estimated waveguide temperature is determined without the use of a temperature sensing device.

Abstract: For a gas turbine engine (10), a method and apparatus for determining temperature of combustion gas in a flow path (17) of the engine. In one embodiment a waveguide (30) includes a cavity (36) with a first waveguide end (32) including a barrier layer (58) which may be a membrane. With the first end positioned to inject an acoustic signal into the flow path, the barrier layer (58) isolates the cavity from combustion gas. Acoustic instrumentation positioned along the surface (38i) of a wall (38) of the waveguide provides generation and propagation of acoustic signals into the flow path for detection and measurement after reflection back into the cavity. The wall may include sections of two different materials, one material having a higher melting temperature than the other, or one material having greater electrically isolating properties than the other section.

Abstract: The state of a flame in a subject combustor of a gas turbine engine is acoustically monitored using a dynamic pressure sensor within the subject combustor and one or more additional sensors in nearby combustors. Dynamic pressure sensor output signals from the sensors are cross correlated to identify acoustic oscillations generated by a flame in the subject combustor and received by the sensors. The cross correlation may be constrained by a maximum time delay between correlated components of the signals, based on physical characteristics.

Abstract: Systems and methods are provided to determine a subset of D microphones in a set of N microphones on a perimeter of a space to monitor a target location. The space is divided into L interference locations. An equation is solved to determine microphone weights for the N microphones by minimizing the maximum gain for signals related to the target location and interference locations, further optimized over an l1 penalty by applying a Lagrange multiplier to an l1 norm of the microphone weights in a manner that determines a set of D non-zero microphones weights and a set of (N-D) microphone weights that are zero or close to zero. Microphone weights are determined for at least 2 different frequencies.

Abstract: Techniques for monitoring health of an igniter (202) in a gas turbine engine (201) include a sensor (270) mounted to detect signals in a combustor (260) and a processor (180) in electrical communication with the sensor. The processor is configured to receive (601) from the sensor first data that indicates signal changes in each of a plurality of time bins during operation of the igniter in the combustor. Information characteristics of the first data are determined (603). A value is determined (615) of a similarity measure that indicates similarity of the information characteristics to target information characteristics. Based on the value of the similarity measure, a condition of the igniter is determined (633) and a device is operated (635) based on the conditions, for example the condition is presented on a display (714).

Abstract: Techniques for a chamber, such as gas turbine engine (100), surrounding a heated fluid include a sensor (150) mounted in a first wall (228b, 229b) of the chamber to detect phenomenon inside the chamber and a processor (702). The processor is in electrical communication with the sensor and is configured to receive first data, determine a first temperature of the first wall, determine a current path length, determine properties of the fluid flow, and operate a device based on the properties. First data indicates a value of the phenomenon along a path between the first wall and a different wall of the chamber. The current path length (268b) is based on a nominal path length (268a) and thermal expansion of the first wall due to the first temperature. The property of fluid flow in the chamber is based on the first data and the current path length.

Abstract: The flame status of a group of gas turbine combustors is acoustically monitored using dynamic pressure sensors within the combustor. Dynamic pressure sensor output signals are received from the sensors and processed to determine flame status. The signals are processed both by performing a correlation analysis within each combustor and by applying a wavelet-based flame detection algorithm to each output signal. A flame is determined to be present based on the correlation analysis and the wavelet-based flame detection algorithm. The wavelet-based flame detection algorithm is chosen based on whether the gas turbine combustors are in an ignition phase or a monitoring phase.

Abstract: A system and methods to deblend seismic data from a plurality of sources and received by a plurality of sensors as shot gathers are disclosed. The deblending is performed by a Mutual Interdependence Analysis Method to separate contributions of different shots. Deblending is also performed by applying a measure of coherence in parallel data domains such as Common Shot Gather and Common Midpoint. Deblending is also achieved by using the hyperbolic nature of seismic data in the common midpoint domain. Deblended signals are estimated and are applied to create a seismic image. Also, Bergman iteration based migration is applied directly on the blended seismic shot gathers without first deblending as an alternative method. The methods are applied in seismic imaging for exploration of natural resources.

Abstract: Techniques for a chamber, such as gas turbine engine (100), surrounding a heated fluid include a sensor (150) mounted in a first wall (228b, 229b) of the chamber to detect phenomenon inside the chamber and a processor (702). The processor is in electrical communication with the sensor and is configured to receive first data, determine a first temperature of the first wall, determine a current path length, determine properties of the fluid flow, and operate a device based on the properties. First data indicates a value of the phenomenon along a path between the first wall and a different wall of the chamber. The current path length (268b) is based on a nominal path length (268a) and thermal expansion of the first wall due to the first temperature. The property of fluid flow in the chamber is based on the first data and the current path length.

Abstract: Active acoustic velocity and pyrometry-based gas flow velocity and temperature measurement, such as for monitoring of gas turbine combustors, including industrial gas turbine (IGT) combustors is incorporated into the combustion monitoring and control system by addition of an acoustic transmitter or acoustic transceiver that transmits a sound wave in a line-of-sight with a plurality of acoustic sensors, such as dynamic pressure sensors. For velocity measurement, sound transmission time-of-flight that is directed generally along the gas flow path is measured by the controller and correlated with gas flow velocity along the line-of-sight. Similarly, sound transmission time-of-flight is correlated with temperature along the line-of-sight. Path(s) of acoustic transmission serve as velocity or velocity/absolute temperature measurement.

Abstract: A gas turbine engine (10) including a hybrid waveguide (84) for placement adjacent a flow path (17) for hot combustion gases in the engine. The waveguide includes first and second opposing ends (88, 90), and comprises a first section (100) formed of a first material extending from a transition region (104) to the first end (88) and a second section (102) formed of a second material extending from the transition region (104) to the second end (90). In one embodiment the first material is a metal or a ceramic and the second material is an electrically isolating material having a lower thermal conductivity than the material of the first section. In another embodiment a membrane (58) isolates a cavity (36) of the waveguide from combustion gas.

Abstract: For a gas turbine engine (10), a method and apparatus for determining temperature of combustion gas in a flow path (17) of the engine. In one embodiment a waveguide (30) includes a cavity (36) with a first waveguide end (32) including a barrier layer (58) which may be a membrane. With the first end positioned to inject an acoustic signal into the flow path, the barrier layer (58) isolates the cavity from combustion gas. Acoustic instrumentation positioned along the surface (38i) of a wall (38) of the waveguide provides generation and propagation of acoustic signals into the flow path for detection and measurement after reflection back into the cavity. The wall may include sections of two different materials, one material having a higher melting temperature than the other, or one material having greater electrically isolating properties than the other section.

Abstract: A method for measuring air mass flow into a compressor section of a gas turbine engine is provided. Air is introduced into a chamber upstream from an inlet of the compressor section. The chamber includes filter packages with at least some of the filter packages including a flow sensor and a filter structure, the filter structure filtering the air. The flow sensors measure the velocity of the air flowing through the corresponding filter package. A controller uses the air flow sensor signal data to characterize a two dimensional flow field through the chamber. Additionally, a plurality of temperature, humidity, and static pressure sensors are disposed throughout the filter packages. The controller uses the temperature, humidity, and static pressure sensor signal data to characterize a two dimensional density field through the chamber. The controller combines the flow field with the density field to calculate a two dimensional air mass flow field.

Abstract: The state of a flame in a gas turbine combustor is acoustically monitored using a single dynamic pressure sensor within the combustor. A dynamic pressure sensor output signal is received from the single sensor and is processed to determine a flame status. The signal is processed by performing an autocorrelation operation to identify time-separated portions of the signal and to determine that the time-separated portions of the signal include portions indicative of acoustic oscillations emitted by the flame in the gas turbine engine combustor and received directly by the single acoustic sensor, and portions indicative of reflections.

Abstract: The flame status of a group of gas turbine combustors is acoustically monitored using dynamic pressure sensors within the combustor. Dynamic pressure sensor output signals are received from the sensors and processed to determine flame status. The signals are processed both by performing a correlation analysis within each combustor and by applying a wavelet-based flame detection algorithm to each output signal. A flame is determined to be present based on the correlation analysis and the wavelet-based flame detection algorithm. The wavelet-based flame detection algorithm is chosen based on whether the gas turbine combustors are in an ignition phase or a monitoring phase.

Abstract: A method for estimating a time of flight of an acoustic signal in a hot gas flow path having background noise wherein a plurality of transceivers each generate an acoustic signal. The method includes providing an acoustic signal of interest that travels in a direction opposite a reference acoustic signal on a first acoustic path between a pair of transceivers. The method also includes identifying at least one minimum peak height in the acoustic signal of interest having a peak height that is greater than the background noise. Further, the method includes obtaining time of flight information of other acoustic paths having substantially the same path length as the first path to provide a range of time of flights wherein a time of flight that falls within the time of flight range and is associated with a minimum peak height forms the estimated time of flight.