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Author

Arno Volker

Bio: Arno Volker is an academic researcher from Netherlands Organisation for Applied Scientific Research. The author has contributed to research in topics: Guided wave testing & Ultrasonic sensor. The author has an hindex of 9, co-authored 45 publications receiving 215 citations.

Papers
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Proceedings ArticleDOI
05 Mar 2010
TL;DR: In this paper, the authors evaluated the performance of guided wave tomography (GW tomography) for measuring the wall thickness, location and extent of the corrosion in a permanent monitoring system, and the results demonstrate the robustness of the technology under a range of practical conditions.
Abstract: Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation matches very well with the objective to reduce cost while maintaining a high safety level. Guided waves are very attractive for permanent monitoring systems because it provides a wall thickness map in between two sensor rings. The wall thickness map provides quantitative information about the remaining wall thickness, location and extent of the corrosion. The performance of guided wave tomography has been evaluated experimentally assessing the sizing accuracy and the smallest corrosion spots that can be detected with this technology. The results show accurate sizing, with a sizing accuracy better than 10% of the nominal wall thickness. Additionally, the maximum distance between the transmitter and receiver rings and the presence of different coatings has been evaluated. The results demonstrate the robustness of the technology under a range of practical conditions.

31 citations

Journal ArticleDOI
TL;DR: The concept of two-stage beamforming based on virtual source-receivers is exploited, which reduces the front-end computational load while maintaining a similar data rate and frame rate compared to dynamic-receive beamforming.
Abstract: Spatial resolution in medical ultrasound images is a key component in image quality and an important factor for clinical diagnosis. In early systems, the lateral resolution was optimal in the focus but rapidly decreased outside the focal region. Improvements have been found in, e.g., dynamic-receive beamforming, in which the entire image is focused in receive, but this requires complex processing of element data and is not applicable for mechanical scanning of single-element images. This paper exploits the concept of two-stage beamforming based on virtual source–receivers, which reduces the front-end computational load while maintaining a similar data rate and frame rate compared to dynamic-receive beamforming. We introduce frequency–wavenumber domain data processing to obtain fast second-stage data processing while having similarly high lateral resolution as dynamic-receive beamforming and processing in time-space domain. The technique is very suitable in combination with emerging technologies such as application-specific integrated circuits (ASICs), hand-held devices, and wireless data transfer. The suggested method consists of three steps. In the first step, single-focused RF line data are shifted in time to relocate the focal point to a new origin $t^\prime = 0,\;z^\prime = 0$ . This new origin is considered as an array of virtual source/receiver pairs, as has been suggested previously in literature. In the second step, the dataset is efficiently processed in the wavenumber–frequency domain to form an image that is in focus throughout its entire depth. In the third step, the data shift is undone to obtain a correct depth axis in the image. The method has been tested first with a single-element scanning system and second in a tissue-mimicking phantom using a linear array. In both setups, the method resulted in a $- {6}{\text{-dB}}$ lateral point spread function (PSF) which was constant over the entire depth range, and similar to dynamic-receive beamforming and synthetic aperture sequential beamforming. The signal-to-noise ratio increased by 6 dB in both the near field and far field. These results show that the second-stage processing algorithm effectively produces a focused image over the entire depth range from a single-focused ultrasound field.

22 citations

Patent
06 Jul 2012
TL;DR: In this article, 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 into the wall of the pipe, wherein the transmitter is further arranged to binary code information conceived to be transmitted with the acoustic waves.
Abstract: 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.

18 citations

Patent
19 Feb 2008
TL;DR: In this paper, the authors proposed a method of modelling a surface of an object using ultrasonic transducers mounted on the surface of the object, which consists of: • providing a model of the surface, the model comprising a primary set of surface points indicative of the height of the surfaces, transmitting pulsed waves from a first transducer to one or more second transducers, defining a respective path along the surface.
Abstract: A method of modelling a surface (3) of an object (2) using ultrasonic transducers (4, 5) mounted on the surface comprises the steps of: • providing a model of the surface, the model comprising a primary set of surface points indicative of the height of the surface, • transmitting pulsed waves from a first transducer (4) to one or more second transducers (5), the first transducer and each second transducer defining a respective path along the surface, • measuring travel times of the pulsed waves along each path, • calculating travel times based on the model of the surface, • adjusting the model of the surface in response to any discrepancies between the measured travel times and the calculated travel times, and • repeating the steps of transmitting, measuring, calculating and adjusting until the discrepancies are smaller than a predetermined threshold. The step of calculating the travel times comprises the sub-step of interpolating the primary set of surface points in order to obtain an expanded secondary set of surface points, the travel times being calculated using the expanded set. Thus the number of surface points to be determined is substantially reduced.

14 citations

Journal ArticleDOI
TL;DR: In this paper, the amplitude of a received reflection depends on the position of the reflecting particle in the measurement volume and on the dimensions and shape of the particle, and a forward analytical model describes the relations between the suspension properties (particle size distribution and particle concentration) and measured histogram of amplitudes.

12 citations


Cited by
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Journal ArticleDOI
TL;DR: This paper proposes a novel method for suppressing the unwanted S0 mode based on the Poisson effect of the material by optimizing the angle of inclination of the equivalent transduction force of the Electromagnetic Acoustic Transducers (EMATs) used for generation and detection purposes.

106 citations

Journal ArticleDOI
TL;DR: The results suggest that the FWI method is capable to reconstruct the thickness map of a irregularly shaped defect accurately on a 10-mm-thick plate with the thickness error within 0.5 mm.
Abstract: In this paper, a guided wave tomography method based on full waveform inversion (FWI) is developed for accurate and high-resolution reconstruction of the remaining wall thickness in isotropic plates. The forward model is computed in the frequency domain by solving a full-wave equation in a two-dimensional (2-D) acoustic model, accounting for higher order effects such as diffractions and multiple scattering. Both numerical simulations and experiments were carried out to obtain the signals of a dispersive guided mode propagating through defects. The inversion was based on local optimization of a waveform misfit function between modeled and measured data, and was applied iteratively to discrete frequency components from low to high frequencies. The resulting wave velocity maps were then converted to thickness maps by the dispersion characteristics of selected guided modes. The results suggest that the FWI method is capable to reconstruct the thickness map of a irregularly shaped defect accurately on a 10-mm-thick plate with the thickness error within 0.5 mm.

100 citations

Journal ArticleDOI
TL;DR: This article surveys recent advances in ultrasound haptic technology and discusses the fundamentals of this haptictechnology, how a variety of perceptible sensations are rendered, and how it is currently being used to enable novel interaction techniques.
Abstract: Ultrasound haptics is a contactless haptic technology that enables novel mid-air interactions with rich multisensory feedback. This article surveys recent advances in ultrasound haptic technology. We discuss the fundamentals of this haptic technology, how a variety of perceptible sensations are rendered, and how it is currently being used to enable novel interaction techniques. We summarize its strengths, weaknesses, and potential applications across various domains. We conclude with our perspective on key directions for this promising haptic technology.

83 citations