| 1. |
- Arne, B., et al.
(författare)
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Laser ablation breakdown spectroscopy technique for simultaneous analysis of steel and slags in metallurgical samples
- 2009
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Ingår i: Yejin Fenxi/Metallurgical Analysis. - 1000-7571. ; 29:2, s. s.8-13
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Tidskriftsartikel (refereegranskat)abstract
- The original purpose of this research was to develop a method for fast, simultaneous analysis of both the steel and slag content of heterogeneous metallurgical samples for process control. The method is based on Laser Induced Breakdown Spectroscopy (LIBS). The reason for choosing LIBS is that it can be employed for both conductive and non-conductive materials, and is relatively insensitive to sample shape and surface finish. The heterogeneous samples produced contain large numbers of sub-millimetre slag particles that cannot be completely separated from the surrounding steel in a LIBS analysis. A method has therefore been developed to perform a line scan analysis with approximately 0.5 mm resolution and 10 mm length along the sample. The laser pulse rate is 20 Hz and the scan speed is 1 mm/s. Slag particles appear in the line scan as "polluted areas" of the steel with very high concentrations of e. g. Ca, Al and Si. A mathematical model was developed to evaluate the data in steps, based on a single calibration. Firstly, "clean steel" areas are identified and the steel composition determined. In the second step, the average composition across the entire length of the scan is determined. In the final step, the average slag composition is determined by means of a difference calculation. The method was tested on several samples from the development of the heterogeneous sampler. It was found that the elements C, Si, Mn, P, S and Al can be determined in the steel with an RSD of a few percent. In the slag, the RSD's are higher, around10% for several important elements. It is expected that the method can be further developed for rapid analysis of smaller non-metallic inclusions.
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| 2. |
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| 3. |
- Bengtson, Arne, et al.
(författare)
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Expert systems for prediction of corrosion properities of Zn-based coatings from the chemical analysis
- 2012
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Ingår i: Yejin Fenxi/Metallurgical Analysis. - 1000-7571. ; 32:4, s. s.1-5
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the work is to develop a general method, to predict the corrosion resistance of Zn-based coatings, expressed as total mass loss in an accelerated salt spray test. The method is to be based on just three analytical parameters; the total coating weights of Zn, Al and Mg. The reason for this restriction is that determination of these three parameters is possible in on-line analysis. The predicted corrosion resistance could then be included in a process/quality control system. Accelerated corrosion tests have been carried out by Swerea KIMAB IC (Institut de Corrosion) in Brest, and CRM in Belgium. Test were run according to the Renault ECC1 test D172028/-C (12 weeks), and with an accelerated cyclic corrosion test developed by CRM. The materials were divided into four corrosion classes according to total mass loss. All corrosion experiments show clearly the well documented positive influence of magnesium and aluminium. In relation to the masses of these elements in the coatings, the influence of both elements is considerably higher than the influence of zinc alone. For this reason, a new quantity is introduced, called "equivalent Zn coating weight". This quantity is a linear combination of the coating weights of zinc, aluminium and magnesium. A model for prediction of corrosion resistance was developed with the expert system, based on a combination of regression analysis and a "decision tree" algorithm. The model was able to correctly classify 25 out of 27 materials based on just the three analytical parameters mentioned above: the total coating weights of zinc, aluminium and magnesium. In conclusion, the approach shows that an accurate prediction of the corrosion behaviour is possible even on-line. For purposes of material development, the expert system can also be expanded to include additional analytical parameters.
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| 4. |
- Bengtson, Arne, et al.
(författare)
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Rapid inclusion characterisation by pulse distribution analysis optical emission spectroscopy-recent development
- 2013
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Ingår i: Yejin Fenxi/Metallurgical Analysis. - 1000-7571. ; 33:1, s. s.7-12
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the work is to further develop and validate the optical emission method pulse distribution analysis (PDA) for rapid inclusion characterisation in steel production. The experimental work was focused on investigation of several operational parameters: spark energy, spark frequency and time gating of signal acquisition. The results showed that a low spark energy improves the detection limit, but at the expense of measuring statistics due to a smaller sample volume. The measuring frequency proved to have no significant influence on the analytical results, but several existing instruments cannot handle the highest spark frequencies above about 300 Hz in PDA mode due to limitations in the electronics. Investigation of time gating (TRS) gave only a marginal improvement in the detection limit of Si outliers above the metallic content. The work also revealed that there is a risk to detect "false" outliers due to asymmetric intensity distributions. This has resulted in the development of more advanced algorithms for outlier detection, increasing the accuracy of the method. Another limitation found is that the particle number density must not exceed about 10 000 inclusions/mm3 for the method to effectively detect single inclusions. A method to overcome this limitation has been suggested, but not yet evaluated. The accuracy of quantitative determination of the Al content in inclusions has been verified by reference methods. In conclusion, it has been demonstrated that state-of-the-art PDA is a very powerful technique for rapid inclusion characterisation in steels. Furthermore, the speed of analysis is sufficiently high for process feedback and controllable.
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| 5. |
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| 6. |
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| 7. |
- Chen, Fuqiang, et al.
(författare)
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减压阀噪声研究进展
- 2019
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Ingår i: Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering. - 1674-8530. ; 37:1, s. 49-57
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Tidskriftsartikel (refereegranskat)abstract
- In order to comprehensively understand the specific noise generation process inside pressure reducing valves (PRV) and its existing research outcomes, the generation of noise in PRV with its research methods in China and abroad was summarized. Then, the current research status of noise reduction technologies was reviewed from two aspects: source and propagation. Based on analysis and summarization, the major existing problems in current noise reduction technologies were discussed, including complex flow situation in PRV, ambiguity of vortex location and uncertain of interaction between high-velocity jet flows and so on. In the future investigation of noise reduction in PRV, it is advised that the position of noise source in valve should be determined firstly through combination of theoretical analysis, experiment and numerical analysis. Then, the directivity of noise in the valve can be clarified. Thereby, a further study of noise reduction mechanism and technology can be launched. Finally, noise in PRV can be reduced to the utmost extent. In the future, control of noise inside PRV should start with flow mechanism and structural innovation, and then a universal valve design theory with low noise will be put forward. Investigation into noise characteristics in pressure reducing valve can provide a reliable basis for reducing noise effectively.
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| 8. |
- Chen, Shuang, et al.
(författare)
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CH4/Air反扩散射流火焰多组分同步PLIF诊断
- 2018
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Ingår i: Shiyan Liuti Lixue/Journal of Experiments in Fluid Mechanics. - 1672-9897. ; 32:1, s. 26-32
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Tidskriftsartikel (refereegranskat)abstract
- The simultaneous multi-species Planar Laser Induced Fluorescence technique plays an important role in studying the flame structure and the two-dimensional distribution of intermediate species in combustion. The experimental system of OH/CH2O/Acetone-PLIF was built in order to study the CH4-Air inverse diffusion jet (IDJ) flame. The system consists of two sets of lasers, two intensifier-CCD cameras, a temporal controller and several lenses. The strategy of fluorescence excitation, the method of synchronous timing control and image calibration procedures are discussed. The IDJ flame was studied using the simultaneous multi-species PLIF technique, and the reaction zone, pre-heating zone and fuel zone of IDJ flame were determined. Experimental results suggest that the IDJ flame is different from either the normal diffusion flame or the premixed jet flame. The behavior of this type of flame reveals similarity to the partially premixed flame. Compared to OH chemilumiscence images, simultaneous multi-species PLIF can provide more detail and information about the flame structure and it has huge potential in fundamental combustion studies and industrial burner experiments
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| 9. |
- Chen, Xiangrong, 1982, et al.
(författare)
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Study on conducting characteristics of electrical trees in cross-linked polyethylene cable insulation
- 2012
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Ingår i: Wuli Xuebao/Acta Physica Sinica. - : Acta Physica Sinica, Chinese Physical Society and Institute of Physics, Chinese Academy of Sciences. - 1000-3290. ; 61:8, s. Art. no. 087701-
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Tidskriftsartikel (refereegranskat)abstract
- The conducting characteristics of two typical electrical trees in cross-linked polyethylene (XLPE) cable insulation are studied by a combination of optical microscopy observation, partial discharge measurement and con-focal Raman spectroscopy analysis. Although they are grown under similar conditions, these two trees display very different shapes. One is a typical branch-pine tree grown at 9 kV, and the other is a branch tree grown at 11 kV. The growth and the partial discharge regularities show obvious differences. The disordered graphitic carbon is condensed in the main tree channels of the branch-pine tree. From the relative intensity of the graphitic carbon G band to D band, the graphitic domain is estimated to be about 8 nm in size. The tree channel resistance per unit length is less than 10 Ω· μm-1, which is sufficient to prevent the partial discharge from developing within the tree structure. The branch-pine tree shows the features of the conducting tree. The fluorescence background is observed in the channels of branch tree, which shows the existence of the products of the material degradation, but no disordered graphitic carbon is observed in these tree channels. These tree channels display obvious non-conducting characteristics, which is not sufficient to prevent the continuous effect of the partial discharges. Finally, a single channel growth model is proposed for the conducting and non-conducting trees grown in XLPE cable insulation. Based on the equivalent circuit theory, the growth mechanisms of the two trees with different conducting characteristics in XLPE cable insulation are discussed.
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