| 1. |
- Liang, G-B, et al.
(författare)
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Modified regularization method applied to the inversion of particle size distribution from light scattering data
- 2006
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Ingår i: Guangdian Gongcheng. - 1003-501X. ; 33:12, s. 44-49
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Tidskriftsartikel (refereegranskat)abstract
- Laser particle size analyzer is one of the instruments for particle size analysis. Recent developments focus on various algorithms for particle size analysis via light energy distribution based on the Mie scattering theory in the laser analyzer. The determination of the particle size distribution (PSD) from the analyzer requires the inversion of the Fredholm integral equation of the first kind. This equation is an ill-posed one, which can be analyzed by effective algorithms. This paper presents a modified regularization method applied to the inversion of the PSD with the independent models. The Generalized Cross-Validation (GCV) method was used for the selection of a regularization parameter. The Successive Over-Relaxation (SOR) iterative method was applied to improve the exactness and stability of the convergent result. The simulation with the models was carried out. The simulated results are in a good agreement with the data measured from nine standard particulate samples as well as their mixtures. It is indicated that this method can be feasible and effective for the simulation of the PSD from the corresponding light scattering data.
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| 2. |
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| 3. |
- Wang, Q.Z., et al.
(författare)
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The flattened Brazilian disc specimen used for testing elastic modulus, tensile strength and fracture toughness of brittle rocks : analytical and numerical results
- 2004
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - 1365-1609 .- 1873-4545. ; 41:2, s. 245-253
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Tidskriftsartikel (refereegranskat)abstract
- The flattened Brazilian disc specimen is proposed for determination of the elastic modulus E, tensile strength sigma (sub t) and opening mode fracture toughness K (sub IC) for brittle rocks in just one test. This paper is concerned with the theoretical analysis as well as analytical and numerical results for the formulas. According to the results of stress analysis and Griffith's strength criteria, in order to guarantee crack initiation at the centre of the specimen, which is considered to be crucial for the test validity, the loading angle corresponding to the flat end width must be greater than a critical value (2alpha > or =20 degrees ). The analysis shows that, based on the recorded complete load-displacement curve of the specimen (the curve should include the "fluctuation" section after the maximum load), E can be determined by the slope of the section before the maximum load, sigma (sub t) by the maximum load, and K (sub IC) by the local minimum load immediately subsequent to the maximum load. The relevant formulas for the calculation of E, sigma (sub t) , K (sub IC) are obtained, and the key coefficients in these formulas are calibrated by finite-element analysis. In addition, some approximate closed-form formulas based on elasticity are provided, and their accuracy is shown to be adequate by comparison with the finite-element results.
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| 4. |
- Abele, H., et al.
(författare)
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Particle physics at the European Spallation Source
- 2023
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Ingår i: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 1023, s. 1-84
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Forskningsöversikt (refereegranskat)abstract
- Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world’s brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
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| 5. |
- Chen, Y, et al.
(författare)
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Laser surface modified ductile iron by pulsed Nd:YAG laser beam with two-dimensional array distribution
- 2005
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 245:1-4, s. 316-321
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Tidskriftsartikel (refereegranskat)abstract
- A novel modification layer on the surface of pearlite-ferrite matrix ductile iron was fabricated under irradiation of Nd:YAG laser beam equipped with self-designed diffractive optical element (DOE) which produces a 5×5 two-dimensional array distribution at the focal plane. The microstructure of the layer along the surface and the direction of the layer depth had obvious gradient distribution, and therefore the two-dimensional microhardness map of the layer alternated higher hardness with lower hardness. The results showed that the novel modification layer is expected to have excellent combination of strength and toughness
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| 6. |
- Dou, S.X., et al.
(författare)
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Microstructure and flux pinning in superconducting Bi-Pb-Sr-Ca-Cu-O wires
- 1990
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 172:1-2, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- The critical current density (Jc) of Ag-clad Bi-Pb-Sr-Ca-Cu-O wire has been measured to be 1.2×104 A/cm2 at 77 K in zero field. The high Jc is attributed to a combination of elimination of the poisoning effect of Ag on superconductivity, grain alignment, and enhancement of flux pinning. Jc-H dependence was significantly improved in the Ag-clad tape, which has a Jc of 1.0×103 A /cm2 at 77 K and 4000 Oe, while the Jc of the sintered pellet drops two orders of magnitude at only 100 Oe. A pronounced anisotropy in Jc under high magnetic field is attributed to the grain alignment. Planar defects, such as heavy stacking faults parallel to the a-b plane in the rolled tape, are considered to be effective pinning centres.
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| 7. |
- Fan, Y., et al.
(författare)
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Mechanical preparation of nano titanium dioxide powder and its optical properties
- 2007
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Ingår i: Journal of the Chinese Ceramic Society. - 0454-5648. ; 35:7, s. 832-837
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Tidskriftsartikel (refereegranskat)abstract
- mechanical preparation of the nano-sized particles of TiO2 powder by a stirred bead mill was investigated. The particle sizes of the ground products were determined by the acoustic particle sizer, the nitrogen gas adsorption method and a scanning electron microscopy. The diameter of the nano-sized particles, which were obtained after milling for 7 h, is about 50 nm and the specific surface area is up to 70 m2/g. The surface and structure of the samples have been investigated with X-ray diffraction. It is indicated that an intense comminution in the mill leads to a progressive loss in crystallinity of TiO2. The catalytic degradation of methyl orange in water was also studied by a photometer. The results show that the nano-sized particles of TiO2 powder prepared by milling possess photocatalysis effect and are capable of absorption of ultraviolet radiation
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| 8. |
- Liu, X M, et al.
(författare)
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A tool for evaluating the quality of laminated particleboard countertop
- 2016
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Ingår i: Wood and Fiber Science. - 0735-6161. ; 48:4, s. 297-301
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the quality of laminated particleboard, a typical type of laminate was used in laminating particleboard with operational parameters similar to industry operation. Pull-off tests using Elcometer 510 were conducted. In addition, panel vertical density profiles (VDP) and the pH of particleboard at different layers were tested. The results showed that the laminated panel bonded by polyvinyl acetate (PVA) glue had higher pull-off strength than that of the phenol formaldehyde (PF) glue within corresponding sanding thickness. Sanding off 0.0762 mm resulted in higher pull-off strength than sanding off 0.0254 mm. The laminates had the highest pull-off strength when the PB were sanded off 0.0762 mm and glued by PVA. This has provided a solution to improve lamination pull-of strength for industry. The test results have also shown that the laminated panels produced in the manufactures have the potential to be improved. It also indicates that Elcometer 510 is a good tool to evaluate the particleboard lamination quality.
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| 9. |
- Pei, Benyan, et al.
(författare)
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Thermodynamics and kinetics of passive oxidation of Si3N4-bonded sic ceramics
- 1994
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Ingår i: Ceramic Transactions. - 1042-1122. ; 44, s. 253-263
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation reactions of Si3N4-bonded SiC ceramics are more complicated than a single component like SiC or Si3N4. The thermodynamics and kinetics of air oxidation of such ceramics in the temperature range of 900-1300 C are studied. The active to passive transition of oxidation was analysed by thermodynamic calculations using the JANAF table. The weight gain was measured using a TGA technique to study the kinetics. It is shown that all components contribute to the formation of a silica film. The kinetic results indicate that the oxidation reactions of Si3N4-bonded SiC ceramics are controlled by both an interface reaction and diffusion through the product layer. The activation energy obtained for the specimen studied is found to be comparable with that for SiC oxidation as reported in the literature
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| 10. |
- Pöntinen, M., et al.
(författare)
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Euclid: Identification of asteroid streaks in simulated images using deep learning
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 679
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Tidskriftsartikel (refereegranskat)abstract
- The material composition of asteroids is an essential piece of knowledge in the quest to understand the formation and evolution of the Solar System. Visual to near-infrared spectra or multiband photometry is required to constrain the material composition of asteroids, but we currently have such data, especially in the near-infrared wavelengths, for only a limited number of asteroids. This is a significant limitation considering the complex orbital structures of the asteroid populations. Up to 150 000 asteroids will be visible in the images of the upcoming ESA Euclid space telescope, and the instruments of Euclid will offer multiband visual to near-infrared photometry and slitless near-infrared spectra of these objects. Most of the asteroids will appear as streaks in the images. Due to the large number of images and asteroids, automated detection methods are needed. A non-machine-learning approach based on the Streak Det software was previously tested, but the results were not optimal for short and/or faint streaks. We set out to improve the capability to detect asteroid streaks in Euclid images by using deep learning. We built, trained, and tested a three-step machine-learning pipeline with simulated Euclid images. First, a convolutional neural network (CNN) detected streaks and their coordinates in full images, aiming to maximize the completeness (recall) of detections. Then, a recurrent neural network (RNN) merged snippets of long streaks detected in several parts by the CNN. Lastly, gradient-boosted trees (XGBoost) linked detected streaks between different Euclid exposures to reduce the number of false positives and improve the purity (precision) of the sample. The deep-learning pipeline surpasses the completeness and reaches a similar level of purity of a non-machine-learning pipeline based on the StreakDet software. Additionally, the deep-learning pipeline can detect asteroids 0.25–0.5 magnitudes fainter than StreakDet. The deep-learning pipeline could result in a 50% increase in the number of detected asteroids compared to the StreakDet software. There is still scope for further refinement, particularly in improving the accuracy of streak coordinates and enhancing the completeness of the final stage of the pipeline, which involves linking detections across multiple exposures.
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