scholarly journals Characterization of Grain-Size Distribution, Thermal Conductivity, and Gas Diffusivity in Variably Saturated Binary Sand Mixtures

2018 ◽  
Vol 17 (1) ◽  
pp. 180026 ◽  
Author(s):  
T.K.K. Chamindu Deepagoda ◽  
Kathleen Smits ◽  
J.R.R.N. Jayarathne ◽  
Benjamin M. Wallen ◽  
Timothy J. Clough
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Gas Diffusivity

The Influence of Microstructures on the Thermal Conductivity of Polycrystalline UO2

2016 ◽  
Author(s):  
Enze Jin ◽  
Chen Liu ◽  
Heming He
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Method ◽  
Grain Size ◽  
Finite Element ◽  
Pore Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Structural Changes ◽  
Property Changes ◽  
Design Guidance

The thermal conductivity is one of the most important properties for UO2. The influences of microstructure are especially important for UO2 due to the severe structural changes under irradiation conditions. In this study, we have investigated the thermal conductivity of UO2 with different microstructures using Finite Element Method. The thermal conductivity increases with increasing grain size. The grain size distribution has obvious influence on the thermal conductivity especially when there are pores in the polycrystal. The influences of porosity and pore size are very sensitive to the position of the pores. The results obtained in this study are useful for prediction of property changes of UO2 fuel in pile and important to gain some design guidance to tune the properties through the control of the microstructure.

scholarly journals Contribution to Sandy Site Characterization: Spectro-Directional Signature, Grain Size Distribution and Mineralogy Extracted from Sand Samples

2019 ◽  
Vol 11 (20) ◽  
pp. 2446 ◽  
Author(s):  
Viallefont-Robinet ◽  
Bacour ◽  
Bouvet ◽  
Kheireddine ◽  
Ouhssain ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Optical Sensors ◽  
Optical Measurements ◽  
Small Samples ◽  
Spectral Bands ◽  
Reflectance Factor ◽  
Bidirectional Reflectance Distribution

The characterization of sands detailed in this paper has been performed in order to support the in-flight radiometric performance assessment of space-borne optical sensors over the so-called Pseudo-Invariant Calibration Sites (PICS). Although the physical properties of PICS surface are fairly stable in time, the signal measured from space varies with the illumination and the viewing geometries. Thus, there is a need to characterize the spectro-directional properties of PICS. This could be done on a broad scale, thanks to multi-spectral multi-directional space-borne sensors such as the POLDER instrument (with old data). However, interpolating or extrapolating the spectro-directional reflectance measured from space to spectral bands of another sensor is not straightforward. The hyperspectral characterization of sand samples collected within or nearby PICS could contribute to a solution. In this context, a set of 31 sand samples was compiled. The BiConical Reflectance Factor (BCRF), linked to Bidirectional Reflectance Distribution Function (BRDF), was measured between 0.4 and 2.5 µm, over a half hemisphere when the amount of sand in the sample was large enough and for only a single fixed angular configuration for small samples. These optical measurements were complemented by grain size distribution measurements and mineralogical analysis and compiled together with previously published measurements in the so-called PICSAND database, freely available online.

Grain-size distribution of Italian raw materials for building clay products: a reappraisal of the Winkler diagram

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 435-442 ◽  
Author(s):  
M. Dondi ◽  
B. Fabbri ◽  
G. Guarini
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Raw Materials ◽  
New Classification ◽  
X Ray ◽  
Size Characterization ◽  
Good Behaviour ◽  
Hollow Bricks

AbstractThe grain size of raw materials influences their behaviour during the technological process and affects many properties of building clay products. Over the last few years, brickworks have been technologically updated and grain size requirements have been modified to ensure good behaviour during shaping and drying. Therefore, the reference schemes used to assess the suitability of clays, such as the classic Winkler diagram, should be updated.For this purpose, the grain-size distribution of 350 clays currently used in ~240 Italian plants was determined by X-ray monitoring of gravity sedimentation. Raw materials are basically represented by silty clays and clayey silts, while bodies present a narrower grain-size range. With reference to the Winkler diagram, most of the Italian bodies fall within the field of ‘thin-walled hollow bricks’, with no significant differentiation among the various product types.In order to improve the grain-size characterization of bodies, a new classification scheme for Italian raw materials is proposed, based on three ranges: >10 µm, 2-10 µm and <2 µm, respectively. It allows distinction of specific grain-size features of bodies for (a) facing bricks; (b) roofing tiles; and (c) lightweight blocks, paving bricks and hollow slabs.

Contribution to a Technological Characterization of Kaolins from Cuba and Brazil

2006 ◽  
Vol 530-531 ◽  
pp. 720-727
Author(s):  
Guillermo Ruperto Martín Cortés ◽  
Wildor Theodoro Hennies ◽  
Francisco Rolando Valenzuela-Díaz
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Simple Description ◽  
X Ray ◽  
The Republic

This paper studies the main well-know technological types of kaolins clays from the Republic of Cuba and compares it with one from Brazil. A simple description from the Cuban geology and from the involved kaolins deposits is showed. The basic characterization of each kind of kaolin, includes, chemical analyzes, grain size distribution, scanning electronic microscopy, X-ray diffraction and X-ray fluorescence for chemicals. For special assays it had conformed, by a simple axis hand press up to 5 t, test bodies, which had been burnt to the temperatures of 950, 1250 and 1450°C. These results include refractory and contraction results.

Structural Characterization Of SrBi2Ta209 Thin Films

1997 ◽  
Vol 474 ◽  
Author(s):  
E. Ching-Prado ◽  
W. Pérez ◽  
A. Reynés-figueroa ◽  
R. S. Katiyar ◽  
D. Ravichandran ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Bond Length ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Structural Characterization ◽  
Sol Gel ◽  
Frequency Shifts ◽  
Gel Technique

ABSTRACTThin films of SrBiTa2O9, (SBT) were deposited on Si using Sol-Gel technique. The thicknesses of the films are 200 nm (A) and 400 nm (B), respectively. SEM studies show isolated grains in both SBT films with a grain size distribution between 0.1 and 0.5 μ. However, most of the grain size in the film is smaller than 0.1 μ. EDX analysis indicates that the films are inhomogeneous. FTIR external reflectivity measurements of the samples show bands around 1260, 936(for SBT2), 955(for SBT4), 770, 600 cm−1. Micro Raman spectra shows inhomogeneities in the SBT films. Bands corresponding to the SBT materials were found, but frequency shifts and broadening were observed in almost every band. Particularly, the band around 818 cm−1 was found to change from 785 to 827 cm−1. Also, due to the stretching of the Ta06 octahedron, the Alg mode was found to be approximately 163 cm−1. This change seems to be related to the Ta-0 bond length.

Microstructural Characterization of Copper Thin Films on Metallic Underlayers

1994 ◽  
Vol 338 ◽  
Author(s):  
E. M. Zielinski ◽  
R. P. Vinci ◽  
J. C. Bravman
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Microstructural Characterization ◽  
Abnormal Growth ◽  
Annealing Temperatures ◽  
Bimodal Grain Size ◽  
Bimodal Grain Size Distribution

ABSTRACTGrain size distribution and texture of thin films of sputtered copper were characterized as a function of underlayer choice, deposition temperature and annealing temperature. For Cu deposited on Ta at room temperature and annealed at 100, 150, 200 and 250 °C, abnormal growth of the (100) orientation was observed for annealing temperatures above 150 °C, resulting in a bimodal grain size distribution. This orientation was also seen to grow abnormally for films deposited and annealed under identical conditions, but with a W underlayer. (100) growth for this case was observed at annealing temperatures as low as 100 °C. Abnormal grain growth was suppressed for Cu deposited on Ta at 150 °C and annealed to 250 °C. A bimodal grain size distribution was observed in a similar sample deposited on W under identical conditions, however, the abnormally growing orientation for this case was observed to be the (111) orientation, not the (100) orientation.

Sign in / Sign up

Export Citation Format

Share Document