摘要:
A position dependent wave vector amplitude of vibrations on a surface of a structure is determined from acoustic measurements using a sensing device at distance from the surface. The device contains an array of microphones in a fluid medium outside the structure. Vibrations in the structure, which travel through the structure e.g. as Lamb waves. This generates sound outside the structure by leakage of sound waves from the surface of the structure. The microphones obtain measured signals from the sound. Furthermore, a measurement of such as distance is obtained that depends on the measurement position where the array of microphones is provided. The parameter is used in an inverse wave field propagation model for sound propagation in the fluid medium between the surface of the structure and the array of microphones. The inverse wave field propagation model is applied to the measured signals to obtain a position dependent estimation of the sound amplitude and/or phase at the surface. The wave vector amplitude of the vibration as a function of position on the surface is computed from the position dependent estimation.
摘要:
The invention relates to a telemetry system for use in a pipe having a wall, comprising a transmitter adapted to generate at least one acoustic wave in a frequency range of about 50 - 300kHz and to inject the acoustic wave in the wall of the pipe, wherein the transmitter is further arranged to binary code information conceived to be transmitted with the acoustic wave. The invention further related to a pipe comprising the telemetry system and to a method of transmitting information via a pipe.
摘要:
Translations of an object in a plurality of different spatial directions are measured using a plurality of interferometers to detect interference with light that has been reflected from a diffusively reflective surface, preferably using diffuse reflection from the same planar surface to measure in each of the different spatial directions. At least the interferometers that measure translation in directions that are not perpendicular to the surface each comprises a single mode fiber and a collimator configured to transmit the outgoing light to the object successively through the single mode fiber and the collimator, and to collect reflection into the single mode fiber with the collimator both along a same beam direction. It has been found that, when reflection of a beam with a beam direction at an oblique angle to a diffusively reflective surface is used, the interference resulting from translation of the object is due substantially only to translation in the beam direction.
摘要:
Improved imaging is provided for structures under test that have propagation direction dependent ultrasound propagation speed or position dependent ultrasound propagation speed due to fibrous, coarse grain or single crystalline material. A set reflection points is selected in the structure under test and ultrasound propagation time delays between the reflection point or points on one hand and the plurality of positions on the other hand that fit an observed time delay of the detected reflections are computed. This may be done by means of an iterative method. In the iterative method a synthetically focused ultrasound beam is realized by summing measurements after compensation for propagation time delay from different transmitting transducers to the reflection points. Time delays to receiving transducers are measured from the arrival time of reflections of this synthetically focused ultrasound beam, and the propagation time delay from different transmitting transducers is iteratively adapted until it matches time delays corresponding to the measured arrival times. Time delays to other points in the structure under test are interpolated between the selected reflection points and used in the computation of an image of reflections within the structure under test.
摘要:
Method and system for assessing corrosion and/or degradation of a pipeline for the transportation of any medium, comprising an array of local sensor modules over the length of the pipeline and arranged for measuring local temperature and humidity values at the pipeline and means for transmitting those values, along with sensor module identifiers, to processing means, as well as means for receiving the sensor module identifiers and local temperature and humidity values measured at the pipeline and inputting them into assessment means arranged for assessing local indicators related to the local corrosion and/or degradation of the pipeline. Wireless transmission means may be used for transmitting the values, along with the sensor module identifiers, to the processing means. The local sensor modules may comprise means for harvesting energy from sunlight and/or temperature differences between the pipeline and its environment.