| 1. |
- Wiklund, M, et al.
(författare)
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Ultrasonic-trap-enhanced selectivity in capillary electrophoresis.
- 2003
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Ingår i: Ultrasonics. - 0041-624X. ; 41:4, s. 329-333
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Tidskriftsartikel (refereegranskat)abstract
- We combine ultrasonic trapping and capillary electrophoresis (CE) with the goal to detect ultra-low concentrations of proteins via size-selective separation and enrichment of antibody-coated latex spheres. An 8.5 MHz standing ultrasonic wave is longitudinally coupled into the sub-100-small mu, Greekm diam capillary of the CE system. Competition between acoustic and viscous forces result in in-flow separation of small mu, Greekm-diam spheres according to their size. Experiments separating 2.8- and 2.1-small mu, Greekm-diam fluorescent latex particles, which model a protein-specific immunocomplex/free particle mixture, indicate a potential improvement of the concentration limit of detection of 104 compared to current CE systems. Theoretical calculations show room for further improvement.
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| 2. |
- Carlson, Johan, et al.
(författare)
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A simple scattering model for measuring particle mass fractions in multiphase flows
- 2002
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Ingår i: Ultrasonics. - 0041-624X .- 1874-9968. ; 39:8, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a simple theoretical model of how pulsed ultrasound is attenuated by the particles in a solid/liquid flow. The theoretical model is then used to predict the attenuation of sound, given the mass fraction, the density, and the size distribution of the solid particles. The model is verified experimentally for suspensions of 0–10% (by mass) Dolomite ((Ca,Mg)CO3) particles and water. The experimental results show that the attenuation of sound due to particles varies linearly with mass fraction, and that the proposed theoretical model can be used to predict this attenuation. In all experiments the transmitter and receiver array were clamped onto the pipe wall, thus providing a completely non-invasive and non-intrusive measurement technique.
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| 3. |
- Delsing, Jerker
(författare)
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Ultrasonic gas flow meter with corrections for large dynamic metering range
- 1989
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Ingår i: Ultrasonics. - 0041-624X .- 1874-9968. ; 27:6, s. 349-356
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Tidskriftsartikel (refereegranskat)abstract
- Extreme accuracy is required in sing-around type gas flow meters in the sing-around period measurement. Thus the detection of the ultrasound is critical. Accurate detection of an ultrasound pulse transmitted through gas is not straightforward. Normally a zero crossing technique is applied, where a level trigger determines when to enable the zero crossing triggering. In a flowing gas, the ultrasound amplitude is modulated due to turbulence, humidity and changes in dynamic gas pressure. This introduces uncertainty as to the cycle in which the ultrasound pulse is detected. This in turn results in large errors in sing-around type gas flow meters. This paper discusses a new correction algorithm which will eliminate such trigger errors. To accomplish the verification of the new correction algorithm, a microprocessor-based sing-around gas flow meter, using 500 kHz ultrasound has been designed. The correction algorithm significantly increases the repeatability of this meter. Repeatability better than 0.5% over a dynamic meter range of 1 to 35 has been measured. Limitations of the sing-around method imposed by the new correction algorithm have been derived theoretically.
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| 4. |
- van Deventer, Jan, et al.
(författare)
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Apparent transducer non-reciprocity in an ultrasonic flow meter
- 2002
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Ingår i: Ultrasonics. - 0041-624X .- 1874-9968. ; 40:1-8, s. 403-405
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the effects of non-identical ultrasonic transducers on reciprocity and zero-flow calibration in transit time flow meters. According to the theorem of reciprocity, there should not be any difference between the up- and downstream acoustic times of flight in a zero-flow situation. This would thus eliminate zero-flow estimation drifts. The flow meter is modeled as a one dimensional system with equivalent electrical circuits and simulated with simulation program with integrated circuits emphasis. The work shows that variations between the two transducers cause false estimates of flow and indicate which parameters have the largest influence. It indicates that reciprocity holds only for identical transducers.
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| 5. |
- Wiklund, Martin, et al.
(författare)
-
Ultrasonic-trap-enhanced selectivity in capillary electrophoresis
- 2003
-
Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 41:4, s. 329-333
-
Tidskriftsartikel (refereegranskat)abstract
- We combine ultrasonic trapping and capillary electrophoresis (CE) with the goal to detect ultra-low concentrations of proteins via size-selective separation and enrichment of antibody-coated latex spheres. An 8.5 MHz standing ultrasonic wave is longitudinally coupled into the sub-100-muM diam capillary of the CE system. Competition between acoustic and viscous forces result in inflow separation of mum-diam spheres according to their size. Experiments separating 2.8- and 2.1-mum-diam fluorescent latex particles, which model a protein-specific immunocomplex/free particle mixture, indicate a potential improvement of the concentration limit of detection of 10(4) compared to current CE systems. Theoretical calculations show room for further improvement.
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| 6. |
- Aitomäki, Yvonne, et al.
(författare)
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Material property estimates from ultrasound attenuation in fibre suspensions
- 2009
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Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 49:4-5, s. 432-437
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Tidskriftsartikel (refereegranskat)abstract
- An investigation of a new method for measuring fibre material properties from ultrasonic attenuation in a dilute suspension of synthetic fibres of uniform geometry is presented. The method is based on inversely solving an ultrasound scattering and absorption model of suspended fibres in water for the material properties of the fibres. Experimental results were obtained from three suspensions of nylon 66 fibres each with different fibre diameters. A forward solution to the model with reference material values is compared to experimental data to verify the model's behaviour. Estimates of the shear and Young's modulus, the compressional wave velocity, Poisson's ratio and loss tangent from nylon 66 fibres are compared to data available from other sources. Experimental data confirms that the model successfully predicts that the resonance features in the frequency response of the attenuation are a function of diameter. Consistent estimated values for the compressional wave velocity and the Poisson's ratio were found to be difficult to obtain but in combination gave values of shear modulus within previously reported values and with low sensitivity to noise. Young's modulus was underestimated by 54% but was consistent and had low sensitivity to noise. The underestimation is believed to be caused by the assumption of isotropic material used in the model. Additional tests on isotropic fibre would confirm this. Further analysis of the model sensitivity and the reasons for the resonance features are required.
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| 7. |
- Bezek, Can Deniz, et al.
(författare)
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Analytical Estimation of Beamforming Speed-of-Sound Using Transmission Geometry
- 2023
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Ingår i: Ultrasonics. - : Elsevier. - 0041-624X .- 1874-9968. ; 134
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Tidskriftsartikel (refereegranskat)abstract
- Most ultrasound imaging techniques necessitate the fundamental step of converting temporal signals received from transducer elements into a spatial echogenecity map. This beamforming (BF) step requires the knowledge of speed-of-sound (SoS) value in the imaged medium. An incorrect assumption of BF SoS leads to aberration artifacts, not only deteriorating the quality and resolution of conventional brightness mode (B-mode) images, hence limiting their clinical usability, but also impairing other ultrasound modalities such as elastography and spatial SoS reconstructions, which rely on faithfully beamformed images as their input. In this work, we propose an analytical method for estimating BF SoS. We show that pixel-wise relative shifts between frames beamformed with an assumed SoS is a function of geometric disparities of the transmission paths and the error in such SoS assumption. Using this relation, we devise an analytical model, the closed form solution of which yields the difference between the assumed and the true SoS in the medium. Based on this, we correct the BF SoS, which can also be applied iteratively. Both in simulations and experiments, lateral B-mode resolution is shown to be improved by ≈ 25% compared to that with an initial SoS assumption error of 3.3% (50 m/s), while localization artifacts from beamforming are also corrected. After 5 iterations, our method achieves BF SoS errors of under 0.6 m/s in simulations. Residual time-delay errors in beamforming 32 numerical phantoms are shown to reduce down to 0.07 µs, with average improvements of up to 21 folds compared to initial inaccurate assumptions. We additionally show the utility of the proposed method in imaging local SoS maps, where using our correction method reduces reconstruction root-mean-square errors substantially, down to their lower-bound with actual BF SoS.
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| 8. |
- Broberg, Patrik, 1983-, et al.
(författare)
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Improved Corner Detection by Ultrasonic Testing using Phase Analysis
- 2013
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Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 53:2, s. 630-634
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Tidskriftsartikel (refereegranskat)abstract
- In ultrasonic testing, corners are used for sensitivity calibration in the form of notches, for measuring the sound velocity in the material, and as known reference points during testing. A 90° corner will always reflect incoming waves in the opposite direction due to a double reflection and therefore give a strong echo. This article presents a method for separating the echo from a corner from other echoes and more accurately find the position of the corner. The method is based on analysing the phase of the reflected signal. The proposed method was tested on a steel calibration block and the width of the indication was reduced by up to 50% compared to the amplitude signal. This results in a more accurate positioning of the corner. Using the phase instead of the amplitude will also improve the reliability, since reflections other than from corners will disappear.
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| 9. |
- Chai, Guocai, et al.
(författare)
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Study of Crack Initiation or Damage in Very High Cycle Fatigue Using Ultrasonic Fatigue Test and Microstructure Analysis
- 2013
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Ingår i: Ultrasonics. - : Elsevier. - 0041-624X .- 1874-9968. ; 53:8, s. 1406-1411
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Tidskriftsartikel (refereegranskat)abstract
- Fatigue damage behaviors of four metal materials in the very high cycle fatigue (VHCF) regime have been studied using ultrasonic fatigue test and microstructure analysis. The results show that the fatigue crack initiation in VHCF regime could occur at subsurface non-defect fatigue crack origin (SNDFCO), where the accumulated cyclic strains or damage in the specimens were highly localized, especially in the materials with some softer phase, where the local maximum strain can be eight times higher than the average strain value in the specimen. This high strain localization can cause a local plasticity exhaustion that leads to a stress concentration and consequently fatigue crack initiation, and finally the formation of SNDFCO. For pure single phase austenitic material, strain localization can also occur due to dislocation accumulation at or near grain boundaries, which can become fatigue crack initiation origin in the VHCF regime. The results in this study show that fatigue damage and crack initiation mechanisms in the VHCF regime can be different in different metals due to the mechanisms for local plasticity exhaustion.
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| 10. |
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