| 1. |
- Blomquist, Mats, et al.
(författare)
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Range camera on conveyor belts: estimating size distribution and systematic errors due to occlusion
- 1999
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 118, s. 118-126
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Tidskriftsartikel (refereegranskat)abstract
- When range cameras are used for analyzing irregular material on a conveyor belt there will be complications such as missing segments caused by occlusion. Also, a number of range discontinuities will be present. In the framework towards stochastic geometry, conditions are found for the cases when range discontinuities take place. The test objects are pellets for the steel industry. An illuminating laser plane will give range discontinuities at the edges of each individual object. These discontinuities are used to detect and measure the chord created by the intersection of the laser plane and the object. From the measured chords we derive the average diameter and its variance. An improved method is to use a pair of parallel illuminating light planes to extract two chords. The estimation error for this method is not larger than the natural shape fluctuations (the difference in diameter) for the pellets. The laser-camera optronics is sensitive enough both for material on a conveyor belt and free falling material leaving the conveyor.
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| 2. |
- Filippidis, G, et al.
(författare)
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Effect of liquid nitrogen and formalin-based conservation in the in-vitro measurement of laser-induced fluorescence of peripheral vascular tissue
- 1997
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Ingår i: OPTICAL BIOPSIES AND MICROSCOPIC TECHNIQUES II. - : SPIE. - 1996-756X .- 0277-786X. - 0819426296 ; 3197, s. 27-31
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Konferensbidrag (refereegranskat)abstract
- In order to investigate the effects of conservation in liquid nitrogen and formalin on peripheral vascular tissue (abdominal aortic, femoral and flank artery tissue) laser-induced fluorescence spectra were recorded during the exposure of these tissues to He-Cd radiation (442 nm). The spectral distribution of tissue fluorescence allowed the development of simple algorithms based on the intensity difference in order to discriminate the tissue samples when they were fresh and after they were stored for 24 and 48 hours in liquid nitrogen or formalin.
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| 3. |
- Milz, Mathias, et al.
(författare)
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Automated quality control of scene and residual FTIR spectra
- 1999
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 3821, s. 404-415
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Tidskriftsartikel (refereegranskat)abstract
- Spectrally high-resolved infrared spectra from Fourier transform experiments are often used to determine atmospheric parameters. Reliability of results depends on the quality of the measured spectra and on the successful fit of modeled spectra to the measured ones. Algorithms are presented which enable automated quality control of measured spectra as well as the differences between measured and the calculated spectra, so-called residual spectra. The measured scene spectrum is checked for successful phase correction, the compliance of given maximum and minimum envelope functions, spectral patterns in the variance spectrum, which is calculated during coaddition of several spectra, if applicable. The symmetry of isolated lines, the consistence of expected and real noise, and the plausibility of the magnitude of background radiation are assessed.The quality of the spectral fit first is assessed by means of the X2-test and, is checked for superimposed functions, periodicities, spectral signatures, and conspicuous determine possible calculated spectra.
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| 4. |
- Milz, Mathias, et al.
(författare)
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Retrieval of water vapour in the upper troposphere/lower stratosphere from mipas envisat limb emission spectra
- 1999
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 3756, s. 536-543
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Tidskriftsartikel (refereegranskat)abstract
- Global Measurements of water vapor in the upper troposphere and lower stratosphere (UT/LS) are required to assess its influence on the radiation budget of the Earth and for its use as a suitable tracer for the study of troposphere-stratosphere exchange processes(STE). MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) is a Fourier transform spectrometer measuring limb emission spectra. The field of view of the satellite-borne MIPAS/Envisat is rather wide compared to horizontal and vertical structures in real water vapor distributions (e.g. hygropause). Our aim is to derive UT/LS water vapor profiles from MIPAS/Envisat data with optimized spatial resolution and accuracy. The retrieval errors and vertical resolution were assessed in an altitude- range 5 - 25 km with respect to a MIPAS standard observation scenario and the retrieval of the water vapor profile to be performed on the measurement grid. As target parameters we used water vapor and continuum in the first case and water vapor, temperature and continuum in the second scenario. Improvements by joint retrieval of water vapor and temperature are investigated, in particular for saturated H2O- signatures originating fromthe troposphere. The vertical resolution was estimated by the use of so-called averaging kernels.
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| 5. |
- Schedin, Staffan, et al.
(författare)
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Measurement of the density field around an airgun muzzle by pulsed TV holography
- 1999
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; :3823, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- The density distribution in the air surrounding an airgun muzzle is visualized using pulsed TV holography. A ruby laser emitting short coherent light pulses (30 ns) is used as light source. Pulsed holograms are captured by a CCD-camera and their optical phase difference is evaluated by means of the Fourier transform method. A number of experiments are performed where the event is recorded at different instants of time as the lead bullet is about to leave the muzzle. Phase maps showing the integrated density distribution are presented. A jet with decreasing density ahead of the bullet can be observed. At the moment the bullet leaves the muzzle, a spherical sound pressure wave starts to propagate out into the air. The density in the jet in front of the traveling bullet can be calculated by means of full shock-wave theory. The theory confirms the decrease in density observed in the measurements
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| 6. |
- Andersson, Åke, et al.
(författare)
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Observation of coherent synchrotron radiation from a 1 mm electron bunch at the MAX-I storage ring
- 1999
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X. ; 3775, s. 77-87
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Tidskriftsartikel (refereegranskat)abstract
- The coherent generation of synchrotron radiation by an electron storage ring is predicted for wavelengths equal to or longer than the electron bunch length. With typical bunch lengths of approximately 1 cm, diffraction and chamber- screening effects have so-far blocked observation of coherent radiation from a conventional radiation beam line. In the low-energy, second-generation light source MAX-I, the magnet lattice has been tuned to a small momentum compaction factor, allowing rms bunch lengths as short as 1 mm. Here we report the coherent emission phenomena observed from such a bunch at the infrared beam line attached to the MAX-I ring.The coherent generation of synchrotron radiation by an electron storage ring is predicted for wavelengths equal to or longer than the electron bunch length. With typical bunch lengths of approximately 1 cm, diffraction and chamber- screening effects have so-far blocked observation of coherent radiation from a conventional radiation beam line. In the low-energy, second-generation light source MAX-I, the magnet lattice has been tuned to a small momentum compaction factor, allowing rms bunch lengths as short as 1 mm. Here we report the coherent emission phenomena observed from such a bunch at the infrared beam line attached to the MAX-I ring.
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