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| 2. |
- Martinsson, Pär-Erik, et al.
(författare)
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Ultrasonic classification of gases using principal component analysis
- 2003
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Ingår i: 5th world congress on ultrasonics WCU 2003. - Paris : Institut Biomedical des Cordeliers, Université Pierre et Marie Curie. - 2952110506 ; , s. 1129-1132
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Konferensbidrag (refereegranskat)abstract
- On-line measurement of the energy content of natural gas is of interest for both industry and customers, since the energy content determines its monetary value. Experiments with pulsed ultrasound show that, in addition to changes in speed of sound and acoustic attenuation, there is also a change in the shape of the sound waveform. In this paper we investigate the feasibility of using Principal Component Analysis (PCA) to quantify this change in pulse shape. The principle is evaluated for Oxygen and Ethane, for different pressures and different temperatures. The results show that by using PCA, it is possible to distinguish between pulses that have propagated through Oxygen from pulses in Ethane.
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| 3. |
- Boezio, M., et al.
(författare)
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The space experiment PAMELA
- 2004
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Ingår i: Nuclear Physics B - Proceedings Supplements. - : Elsevier BV. ; , s. 39-46
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Konferensbidrag (refereegranskat)abstract
- We present in this paper a status report of the space experiment PAMELA. PAMELA is a satellite-borne experiment which primarily aims to measure the antiproton and positron spectra in the cosmic radiation over a large energy range (from 80 MeV up to 190 GeV for antiprotons and from 50 MeV up to 270 GeV for positrons) and to search for antinuclei with a sensitivity of the order of 10(-8) in the antihelium/ helium ratio. In addition, it will measure the light nucleax component of cosmic rays and investigate phenomena connected with Solar and Earth physics. The apparatus will be installed onboard the polar orbiting Resurs DK1 satellite, which will be launched into space by a Soyuz TM2 rocket in 2004 from Baikonur cosmodrome in Kazakhstan, for a 3 year long mission. PAMELA consists of: a time of flight system, a transition radiation detector, a magnetic spectrometer, an anticoincidence detector, an electromagnetic imaging calorimeter, a shower tail catcher scintillator and a neutron detector.
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| 4. |
- Carlson, Johan, et al.
(författare)
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An ultrasonic pulse-echo technique for monitoring the setting of CaSO4-based bone cement
- 2003
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Ingår i: Biomaterials. - 0142-9612 .- 1878-5905. ; 24:1, s. 71-77
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Tidskriftsartikel (refereegranskat)abstract
- We present a new ultrasonic technique for monitoring the entire setting process of injectable bone cement. The problem with existing standards is their subjectivity. Because of this the results are not comparable between different research groups. A strong advantage with the proposed technique is that it is non-invasive and non-destructive, since no manipulation of the cement sample is needed once the measurement has started. Furthermore, the results are reproducible with small variations. The testing was performed on calcium sulfate cement using an ultrasonic pulse-echo approach. The results show that the acoustic properties of the cement are strongly correlated with the setting time, the density, and the adiabatic bulk modulus. The measured initial and final setting times agree well with the Gillmore needles standard. An important difference compared to the standards, is that the technique presented here allows the user to follow the entire setting process on-line.
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| 5. |
- Carlson, Johan, et al.
(författare)
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Monitoring the setting of injectable calcium-based bone cements using pulse-echo ultrasound
- 2002
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Ingår i: Proceedings. - Piscataway, NJ : IEEE Communications Society. - 0780375823 ; , s. 1293-1296
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Konferensbidrag (refereegranskat)abstract
- The existing standards for determining the setting time of injectable bone substitutes suffers from poor reproducibility and subjectivity. We previously presented an ultrasonic pulse-echo technique that can follow the entire setting reaction on-line, without any mechanical manipulation of the sample. For calcium sulfate hemihydrate (CSH), the new method shows good agreement with the standards, but with much better reproducibility. One problem with the new technique was its sensitivity to temperature fluctuations. In this paper we present a temperature compensation scheme that automatically corrects the measurements for losses caused by temperature changes. The modified method is verified with experiments on /spl alpha/-tricalcium phosphate (/spl alpha/-TCP). Because /spl alpha/-TCP has longer setting time than CSH, the initial method, which is sensitive to temperature, did not work.
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| 6. |
- Nilsson, Malin K, et al.
(författare)
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Monitoring the setting of calcium-based bone cements using pulse-echo ultrasound
- 2002
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Ingår i: Journal of materials science. Materials in medicine. - 0957-4530 .- 1573-4838. ; 13:12, s. 1135-1141
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Tidskriftsartikel (refereegranskat)abstract
- We present a new technique, based on pulse-echo ultrasound, for monitoring the entire setting process of injectable bone cement. This research has been motivated by the lack of satisfying standards. The main problem with existing standards is the subjectivity, which leads to poor reproducibility. Because of this the results are not comparable between different research groups. A strong advantage with the proposed technique is that if low-intensity ultrasound is used, it provides a non-destructive analysis method. Once the cement paste has been applied to the measurement cell, no manipulation is needed throughout the entire setting process. The problem of the ultrasound affecting the setting of certain cement materials has been investigated, and solutions are discussed. The propagation of ultrasound is temperature-dependent, and therefore a technique for automatic compensation for temperature variations is discussed briefly. The testing was performed on -calcium sulfate hemihydrate (CSH) and mixtures of CSH and -tricalcium phosphate (-TCP). The results show that the acoustic properties of the cement are strongly correlated with the setting time, the density, and the adiabatic bulk modulus. The measured initial and final setting times agree well with the Gillmore needles standard. An important difference compared to the standards, is that the technique presented here allows the user to follow the entire setting process on-line.
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