399 research outputs found
Data assimilation in air pollution modelling
No full textElectrical Engineering, Mathematics and Computer Scienc
Magnetoelastic Coupling in Mn-Fe-P-Si Compounds
No full textMn-Fe-P-Si compounds are, to date, the most promising materials for refrigeration and energy conversion applications due to the combination of giant magnetocaloric effect (GMCE) and low material cost. The nature of magneto-elastic transition was studied on both length- and time-scales using neutron diffraction, muSR and Mӧssbauer spectroscopy techniques for Mn-Fe-P-Si compounds. The revealed strong spin-lattice coupling is responsible for the different magnetic orders, the tunability of the phase transition, and the excellent magnetocaloric properties in these compounds. This thesis contributes to a better understanding of the spin-lattice coupling and phase-transition behavior for Mn-Fe-P-Si compounds
Effect of diffuse irradiance on the reflectance factor of reference panels under field conditions
No full textInternational audienc
Evaluation of correction methods for atmospheric effects on temperature measured by ERS1-ATSR, NOAA11-AVHRR and landsat5-TM sensors
No full textNational audienc
Effect of radiometric corrections on NDVI-determined from SPOT-HRV and landsat-TM data
No full textInternational audienc
Growth and Characterisation of Boron Rich Nanomaterials
No full textIn this study nanomaterials are grown in a solid state reaction at 1300C of boron, barium oxide and iron(II/III)oxide powders in an argon atmosphere. The nanomaterials are shown to be grown via vapour based method by growing the nanomaterials on a separate silicon wafer that has been sputtered with iron and placed downstream of the powders in the flow of argon. An area of the silicon wafer is kept free of iron by using a mask when sputtering the wafer. When nanomaterials are grown, the masked area remains free of nanomaterials. This shows that the presence of iron is vital for the nucleation of the nanomaterials and also indicates the possibility of growing these nanomaterials on targeted sites.
The nanomaterials produced are examined and it is found that we have a presence of amorphous, crystalline and multiple twinned nanowires. The evidence collected suggests that 70% of the nanowires are twinned. The single crystal nanowires can be identified as boron carbide by comparing to diffraction pattern simulations of a boron carbide unit cell. The twinned diffraction pattern is shown to be due to different segments of the nanowire being in different diffraction condition by using Dark Field imaging. The Twinned wires are also shown to have at least four segments in a cyclic [001] twinning orientation in simultaneous diffraction condition by comparing to a twinned structure constructed from simulations. Elemental analysis using Electron Energy Loss Spectroscopy and Energy Dispersive X-ray shows that the composition of the nanomaterials is mainly boron and carbon.
The role of the iron layer on the wafer is investigated to see how varying the thickness will affect the nanomaterials grown. It is successfully shown that an increase in the thickness of the iron layer results in a greater density of nanomaterials. However there is no great variation in the average diameter of the nanomaterials produced.
The absence of a visible signal for iron in the Elemental analysis of nanostructure covered silicon wafer shows that the amount of iron in the sample has decreased during the reaction. However iron is found in small amounts in droplet structures at the tips of nanomaterials this is different to work done on a similar system at 1100C. This suggests that the role of the iron in the growth of these nanomaterials at this temperature is not yet understood. However this work has confirmed that the iron is essential for the nucleation of the nanomaterials, but post nucleation growth that was previously assumed to be a conventional VLS growth may switch to an oxide assisted growth mode
SCI citation analysis and impact factor prediction of JZUS-B in 2008
No full textWe analysis the SCI citation of Journal of Zhejiang University-SCIENCE B, predict its 2008 Impact Factor in the range of 0.737~0.915, and list the top-10 SCI cited articles
Effects of extrusion ratio on the ratcheting behavior of extruded AZ31B magnesium alloy under asymmetrical uniaxial cyclic loading
No full textMagnesium alloys are increasingly used in the automotive and aerospace industries for weight reduction and fuel savings. The ratcheting behavior of these alloys is therefore an important consideration. The objective of this investigation was to study the effects of extrusion ratio on the ratcheting behavior of extruded AZ31B magnesium alloy. The experiments have shown that the extruded AZ31B Mg alloy presented the following characteristic behavior with increasing number of loading cycles: first an apparent cyclic softening was observed, then a cyclic hardening occurred, and finally a stable state was reached. This generic behavior can be explained by the fact that the variation trend of the maximum strain with the number of cycles differs from that of the minimum strain. The extrusion ratio did not influence the cyclic softening/hardening behavior or the final ratcheting strain variation trend of the extruded AZ31B Mg alloy with the mean stress and the peak stress. However, the extrusion ratio influenced the final ratcheting strain variation trend of the extruded AZ31B Mg alloy with the stress amplitude. Increasing the extrusion ratio also reduced the ratcheting strain and the effects of the load history on the ratcheting behavior of the extruded AZ31B Mg alloy. © 2010 Elsevier B.V.sponsorship: This work was supported by Project 50801038 supported by National Natural Science Foundation of China, and the Zijin Star Project of Nanjing University of Science and Technology. (National Natural Science Foundation of China|50801038, Nanjing University of Science and Technology)status: Publishe
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