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- Bengtsson, Magnus, et al.
(author)
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Lidar fluorescence measurements of algal growth on electrical insulators
- 2003
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In: 2003 Conference on Lasers and Electro-Optics Europe (CLEO/Europe 2003) (IEEE Cat. No.03TH8666). - 0780377346 ; , s. 473-473
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Conference paper (peer-reviewed)abstract
- Fluorescence measurements using lidar techniques have been shown to be useful for monitoring of algal growth on e.g. historical monuments. In this experiment similar measurements were performed on electrical insulators to examine the correlation between algal growth and the quality of the insulator, a factor of importance in the high-voltage grid management
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| 3. |
- Dernfalk, Andreas, 1975, et al.
(author)
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Laser-induced fluorescence spectroscopy for detection of biological contamination on composite insulators
- 2003
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In: In Proc. 13th International Symposium on High Voltage Engineering, Delft, Netherlands.
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Conference paper (peer-reviewed)abstract
- A new technique for remote detection of biological contamination on high-voltage outdoor insulators has been investigated. The technique, which is based on laser-induced fluorescence (LIF) spectroscopy, has been applied to study surfaces of real silicon rubber insulators from a distance of approximately 60 m. Measurements were performed outdoors on a number of clean, as well as, biologically contaminated insulators. Several types of biological contamination were included, as five of the studied insulators had become covered when installed in Sweden, and another three had been contaminated by fungal growth in laboratory. Fluorescence spectra obtained from the surfaces of the described insulators are presented and the applicability of the technique is discussed and compared with photographic methods.
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| 4. |
- Fridriksson, Steen, 1961-, et al.
(author)
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Intraoperative complications in aneurysm surgery : a prospective national study
- 2002
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In: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 96:3, s. 515-522
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Journal article (peer-reviewed)abstract
- Object. With increasing use of endovascular procedures, the number of aneurysms treated surgically will decline. In this study the authors review complications related to the surgical treatment of aneurysms and address the issue of maintaining quality standards on a national level.Methods. A prospective, nonselected amalgamation of every aneurysm case treated in five of six neurosurgical centers in Sweden during 1 calendar year was undertaken (422 patients; 7.4 persons/100,000 population/year). The treatment protocols at these institutions were very similar. Outcome was assessed using clinical end points. In this series, 84.1% of the patients underwent surgery, and intraoperative complications occurred in 30% of these procedures. Poor outcome from technical complications was seen in 7.9% of the surgically treated patients. Intraoperative aneurysm rupture accounted for 60% and branch sacrifice for 12% of all technical difficulties. Although these complications were significantly related to aneurysm base geometry and the competence of the surgeon, problems still occurred apparently at random and also in the best of hands (17%). The temporary mean occlusion time in the patients who suffered intraoperative aneurysm rupture was twice as long as the temporary arrest of blood flow performed to aid dissection.Conclusions. The results obtained in this series closely reflect the overall management results of this disease and support the conclusion that surgical complications causing a poor outcome can be estimated on a large population-based scale. Intraoperative aneurysm rupture was the most common and most devastating technical complication that occurred. Support was found for a more liberal use of temporary clips early during dissection, regardless of the experience of the surgeon. Temporary regional interruption of arterial blood flow should be a routine method for aneurysm surgery on an everyday basis. A random occurrence of difficult intraoperative problems was clearly shown, and this factor of unpredictability, which is present in any preoperative assessment of risk, strengthens the case for recommending neuroprotection as a routine adjunct to virtually every aneurysm operation, regardless of the surgeon's experience.
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- Lindström, Torgny, et al.
(author)
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Analysis of lidar measurements using nonparametric kernel regression methods
- 2002
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In: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171. ; 74:2, s. 155-165
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Journal article (peer-reviewed)abstract
- The lidar technique is an efficient tool for remote monitoring of the distribution of a number of atmospheric species. We study measurements of sulphur dioxide emitted from the Italian volcano Mt. Etna. This study is focused on the treatment of data and on the procedure to evaluate range-resolved concentrations. In order to make an in-depth analysis, the lidar system was prepared to store measurements of individual backscattered laser pulses. Utilizing these repeated measurements a comparison of three different methods to average the returned signals is made. In the evaluation process we use local polynomial regression to estimate the range-resolved concentrations. Here we calculate optimal bandwidths based on the empirical-bias bandwidth selector. We also compare two different variance estimators for the path-integrated curves: local polynomial variance estimation and variance estimation based on Taylor approximations. Results show that the method performs well. An advantage compared to previous methods for evaluation of lidar measurements is that an estimate of the mean squared error of the estimated concentration can be calculated.
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| 9. |
- Lognoli, D, et al.
(author)
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Fluorescence lidar imaging of the cathedral and baptistery of Parma
- 2003
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In: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171. ; 76:4, s. 457-465
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Journal article (peer-reviewed)abstract
- Extensive fluorescence multispectral imaging of the cathedral and baptistery of Parma, Italy, is reported and discussed. In particular, the first fluorescence imaging data from protection-treated stony materials were recorded. Fluorescence spectra were taken with a mobile lidar system scanning the monument surfaces with a frequency-tripled Nd:YAG laser beam from a distance of about 80 m. For each pixel of the area investigated, a high-spectral-resolution spectrum in the full visible range was acquired. The principal-component analysis technique was used to obtain thematic maps that outlined areas subject to protective treatment and biological growth, and other features, such as different types of stones and decoration pigments.
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