Initial Cube Research Articles

Multipixel anomaly detection in noisy multispectral images

Basing ourselves on a novel segmentation algorithm for multispectral images, we consider how to detect multipixel anomalous objects in image cubes where spectral information is available. In particular, we have developed several morphological filters to compensate for noise that may be present in the initial cube. We show that for different types of noise (Gaussian and speckle), a modification of our morphology technique allows us to better detect targets without an enhanced false-alarm result.

Effect of initial texture on the recrystallization texture of cold rolled AA 5182 aluminum alloy

The effect of initial cube and rotated cube (r-cube) textures prior to cold rolling on the recrystallization and recrystallization texture of cold rolled AA 5182 aluminum alloy was investigated in detail. The transformation kinetics of recrystallization texture during isothermal annealing was quantified by the Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation. The results show that AA 5182 aluminum alloy with different initial cube and r-cube textures exhibits almost the same recrystallization kinetics and recrystallized grain size. The apparent activation energy for recrystallization was estimated from both hardness and texture data to be 230 kJ/mol. The recrystallization texture of AA 5182 aluminum alloy with initial cube and r-cube textures is characterized by the R and cube components. As the annealing temperature increases, the volume fraction of the R component decreases, whereas the volume fraction of the cube component increases. The initial cube and r-cube textures affect the recrystallization texture of AA 5182 aluminum alloy. The AA 5182 aluminum alloy with an initial cube texture exhibits stronger R and Goss components as well as weaker cube and r-cube components than the alloy with an initial r-cube texture after complete recrystallization.

Evolution of strain-induced microstructure and texture in commercial aluminum sheet under balanced biaxial stretching

The evolution of surface topography and crystallographic texture was investigated under balanced biaxial stretching in sheets of the aluminum alloy 5052-H32. Two different lots of material, with an initial nominal thickness of 1 mm, were tested in the as-received condition. Samples with increasing levels of balanced biaxial strain were deformed using a modified Marciniak in-plane stretching test. In general, the sheet materials were microstructurally and crystallographically anisotropic. Between the two lots, the initial microstructure and mechanical properties were found to be equivalent; however, the sheet texture was appreciably different. This latter variation was observed to have an effect on the additional roughening of the surface subsequent to deformation. For a given lot of material, the surface roughness was found to be proportional to the magnitude of the strain. However, while the roughening rates for the two lots were comparable, the lot having a stronger initial {220} texture component was found to roughen to a higher degree. Corresponding changes in the sheet texture were observed to have two regimes as a function of the strain level. In the first regime, typically, for strains (ɛ) up to 0.05, the orientations were found to rotate quickly away from the initial cube {001}〈100〉 orientation observed in the as-received sheet toward positions along the α fiber. Above a strain level of 0.05, the {220} texture component continued to increase with deformation, but at a decreasing rate up to failure of the sheet. The difference in the grain rotation rates observed did not appear to have an effect on the surface roughening, as the relative change of the crystallographic orientations with increasing plastic strain was similar for both heats of material. Instead, it is believed that localized grain or grain-grouping interactions may play a more important role in the surface roughening process.

Microstructures and Tensile Properties of Cold-rolled Thin Foils of Binary Ni-Al γ/γ' Alloys

ABSTRACTThree single crystal plates of γ/γ' Ni-Al two-phase alloys with near cube, Goss and intermediate orientations between cube and Goss were cold-rolled to 300 μm-thick foils with 83% reduction. Tensile tests of the foils were performed at room temperature to study the effect of rolling microstructures and textures on the mechanical properties. The fracture strength of all the foils was very high, 1.4–1.7 GPa, having a small initial normal direction (ND) dependence and a small difference between rolling direction (RD) and transverse direction (TD). The foils fabricated from initial cube and intermediate orientations showed necking and a small fracture elongation when tensile-tested along RD, while the foil fabricated from initial Goss orientation did not show necking and fracture elongation. All the foils showed small fracture elongations due to shear band formation when tensile-tested along TD.

The effects of rockfall volume on runout distance

The main goal of this paper is to clarify the effects of rockfall volume on its fluidization. For this purpose, outdoor rockfall experiments were carried out to analyze runout distances and individual movements of rockfall blocks and numerical simulations were conducted for these experiments to learn more about the mechanism of rockfall fluidization. The rockfall experiments were conducted using an artificial slope on which granite slabs were surfaced and overlaid with cubiformed granite blocks. The size and number of blocks were varied in this series of experiments. Further, numerical simulations were carried out in which the coordinates of individual rockfall blocks were traced in three-dimensional space from rockfall initiation to final deposition. It became clear from the experiments and simulations that the runout distance had a positive correlation with the rockfall volume (number of rockfall blocks) and the runout distance of the gravity center of deposited rockfall mass had a negative correlation with the rockfall volume. To clarify the mechanism of these two phenomena, the positions of individual blocks from initial arrangements to final depositions were traced in the experimental and numerical simulations. This revealed that the relative positions of each block along the slope direction were not changed during rockfall movement. The reason for the block-sequence preservation was that front facing blocks in the initial cube arrangement accelerated and rear facing blocks decelerated along the slope by internal collision between blocks. Further, as the rockfall volume increased, the opportunities for impact among the rockfall blocks increased with the front facing blocks pushed farther. Whereas the gravity-center of the deposited rockfall mass had an inclination to travel shorter distances as rockfall blocks increased according to the increase of kinetic energy dispersed by the collision of blocks.

The Effect of Initial Orientations on Recrystallization Textures in Aluminum Alloy 3004

The evolution of microstructure and texture has been investigated in the industrial hot rolled 3004 alloy sheets with different initial orientations. The development of cube texture after complete recrystallization was dominated by an initial cube orientation density and was remarkably promoted when the alloy sheets with partially recrystallized microstructure were cold rolled with a small reduction prior to annealing. To clarify this particular phenomenon, the individual orientation analysis was made by using OIM (Orientation Imaging Microscopy). It was found in the partially recrystallized microstructure that off-cube grains were destroyed more easily than cube grains during the light cold rolling. Furthermore, the results indicated that cube grains initiated rapid growth at the expense of some off-cube grains during recrystallization if the light cold rolling was performed prior to annealing. It can be concluded that remaining cube grains during the light cold rolling initiated preferentially growth before deformed off-cube grains become prevalent again.

Cube recrystallization texture in warm deformed aluminum: understanding and prediction

The formation of cube {100}〈001〉 recrystallization texture was studied in warm plane-strain deformed aluminum. Recrystallization cube texture intensity increased from 4 to 200 times random, as the true strain was increased from 0.92 to 3.2. The increased cube was primarily due to larger numbers of recrystallized near cube grains, as cube grains had either no or very limited size advantage over grains of other orientations. The origin of cube nucleation was found in the partial stability of existing cube grains which produced thin bands of near-cube oriented deformed material and the lower stored energy of these cube bands. A simple geometrical model is proposed for the prediction of cube recrystallization texture in plane strain deformed f.c.c. metals. The model predicts the frequency of cube recrystallized grains as: N C d R/ λ C. N C is the number of cube grains per (effective) deformed cube band, d R is the recrystallized grain thickness and λ C is the spacing between effective deformed cube bands — all measured along normal direction. N C values were, in material with a low predeformed cube grain frequency, proposed to be either 1 or 2, based on the deformed microstructure. The spacing, λ C was obtained as ( d o/ a C)(1/exp ε), where d o is the initial grain size, a C is the initial cube grain fraction and ε is the true strain. This model was found to work extremely well for λ C> d R in aluminum.

Cube Texture Formation in a Rectangular Die Extruded Al-Mg Alloy

To investigate the early stages of cube texture formation a commercial Al-1.3wt%Mg alloy with different initial textures has been extruded at temperatures between 20 and 500°C. X-ray texture measurements show that the cube component increases with temperature and depends on the initial texture. EBSD reveals that the stronger increase of the cube component in the samples with high initial cube texture extruded above 300°C is due to the stabilization of the initial cube orientation rather than to recrystallization. Investigations of the cube bands show a wide spectrum of neighbour orientations and the presence of large angle grain boundaries. The hot extrusion texture can be simulated with the relaxed constraints Taylor model by taking into account the non-octahedral slip systems.

Modelling recrystallization after hot deformation of aluminium

A physically based model for predicting recrystallization microstructures and textures after hot deformation of aluminium is presented. The modelling approach taken differs from similar models developed for steels. The present model is based on recent experimental investigations directed towards identifying the nature of the nucleation sites for recrystallized grains of different crystallographic orientations. Particle stimulated nucleation, nucleation from cube bands and nucleation from grain boundary regions have been incorporated in the model. The model has been applied to predictions of recrystallized grain sizes and textures of a hot deformed AlMgMn alloy and a commercial purity aluminium alloy. The model responds in a correct way to variations in strain, Zener-Hollomon parameter, initial grain size, initial cube fraction and precipitation. The good agreement between model predictions and experimental results confirms that the recrystallized cube grains are nucleated from “old” cube grains that were present in the starting material and survived the deformation.

Local Textures in Deformed and Recrystallized Aluminium Crystal

The recrystallization mechanisms in deformed aluminium single crystals have been investigated by SEM microdiffraction techniques (ECP and EBSP). Aluminium crystals of (001)(uv0) and (001)[011-] orientations were deformed in plane strain compression to a true strain of ~1 to develop different deformation microstructures. Transition bands separating deformation bands were formed by orientation splitting in the (001)(uv0) crystals, but were not observed in the (001)[011-] crystal.During annealing at 250°C and 400°C, recrystallization nuclei are developed in both the deformed matrix and along transition bands. Matrix nucleation appears to occur by a subgrain coalescence mechanism according to which the new grains are misoriented 15-30° from the average as-deformed material. Transition band nucleation gives an orientation spread 20-30° around the original, undeformed crystal orientation. A well-defined cube recrystallization texture is obtained at 400°C after complete recrystallization of the initial cube crystal.

Preventing contamination during diffusion fermentation of fodder beet cubes by pH control

The efficacy of pH adjustment in control of bacterial contamination during fermentation of fodder beet cubes was investigated in batch (BDF) and sequential batch diffusion fermentation (SBDF). BDF trials indicated that initial cube slurries should be adjusted to pH 2·05. SBDF trials showed that beers with up to 6·45% ethanol could be produced and that the pH should be maintained between pH 2·0–2·2. This pH range prevented bacterial contamination but did not interfere with the production of ethanol.

Statistical averaging in rotationally inelastic gas-surface scattering: The role of surface atom motion

Within the framework of the one-dimensional cube model, the predicted appearance of rotational rainbows and trapping cutoffs in the final rotational state distribution in the limit of zero surface temperature is shown to depend strongly on statistical processes. In particular, inclusion of a distribution of initial surface cube velocities acts to broaden these features.

Dissolution Patterns of Polydisperse Powders: Oxalic Acid Dihydrate

AbstractThe dissolution of oxalic acid dihydrate crystals of log-normal particle-size distribution in 0.1 N HCI was studied. A biphasic cube root dependence was found; the slopes of the initial cube root plots were consistent with theory based on dissolution of isometric, isotropic particles where assumptions were made of: (a) sink conditions, (b) particle-size-independent solubility, and (c) particle-size-independent film thickness of adsorbed liquid layers.