The phase field method has been mainly used to simulate the growth of a single crystal in the past. But polycrystalline materials predominate in engineering. In this work, a phase field model for multigrain solidifica...The phase field method has been mainly used to simulate the growth of a single crystal in the past. But polycrystalline materials predominate in engineering. In this work, a phase field model for multigrain solidification is developed, which takes into account the random crystallographic orientations of crystallites and preserves the rotational invariance of the free energy. The morphological evolution of equiaxial multigrain solidification is predicted and the effect of composition on transformation kinetics is studied. The numerical results indicate that due to the soft impingement of grains the Avrami exponent varies with the initial melt composition and the solidification fraction.展开更多
The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for unders...The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for understanding deep mantle processes. Such high P–T experiments are commonly conducted in a laser-heated diamond anvil cell, producing a multiphase assemblage consisting of 100 nm to submicron crystallite grains. The structures of these lower mantle phases often cannot be preserved upon pressure quenching;thus, in situ characterization is needed. The X-ray diffraction (XRD) pattern of such a multiphase assemblage usually displays a mixture of diffraction spots and rings as a result of the coarse grain size relative to the small X-ray beam size (3–5 lm) available at the synchrotron facilities. Severe peak overlapping from multiple phases renders the powder XRD method inadequate for indexing new phases and minor phases. Consequently, structure determination of new phases in a high P–T multiphase assemblage has been extremely difficult using conventional XRD techniques. Our recent development of multigrain XRD in high-pressure research has enabled the indexation of hundreds of individual crystallite grains simultaneously through the determination of crystallographic orientations for these individual grains. Once indexation is achieved, each grain can be treated as a single crystal. The combined crystallographic information from individual grains can be used to determine the crystal structures of new phases and minor phases simultaneously in a multiphase system. With this new development, we have opened up a new area of crystallography under the high P–T conditions of the deep lower mantle. This paper explains key challenges in studying multiphase systems and demonstrates the unique capabilities of high-pressure multigrain XRD through successful examples of its applications.展开更多
In order to improve the nutritional quality of biscuits, a multigrain premix (MGP) was developed by using whole barley, sorghum, chickpea, pea and defatted soya flour, each at 20% level. The developed MGP had 26.28% p...In order to improve the nutritional quality of biscuits, a multigrain premix (MGP) was developed by using whole barley, sorghum, chickpea, pea and defatted soya flour, each at 20% level. The developed MGP had 26.28% protein, 10.13% insoluble dietary fiber and 7.38% soluble dietary fiber. The experiment was designed to optimise the MGP and wheat flour concentration for the development of multigrain biscuits with high protein, dietary fibre and to maximize the acceptability by the application of central composite rotatable design (CCRD) of Response Surface Methodology (RSM). The levels of incorporation of MGP and wheat flour were taken as variables whereas protein, soluble, insoluble fibers, biscuit dough hardness, breaking strength and overall acceptability (OAA) as responses. The optimum level of MGP and wheat flour obtained using numerical optimization was found to be 40 g and 60 g respectively. The biscuits prepared using these had 16.61% protein, 2.57% soluble fibre, and 6.67% insoluble fibre which is significantly (p ≤ 0.05) higher than control biscuit.展开更多
Multigrain noodles were made by corn and wheat flour as the main ingredients and with small ratios of oat flour, soybean flour and millet flour through extrusion process. Simplex centroid design was used to analyze ge...Multigrain noodles were made by corn and wheat flour as the main ingredients and with small ratios of oat flour, soybean flour and millet flour through extrusion process. Simplex centroid design was used to analyze gelatinization characteristics of the mixed flour, rheological characteristics of the doughs, cooking qualities and sensory qualities of noodles. A proper formula for multigrain noodles obtained as outcome: 45% corn flour, 40% wheat flour, 4% oat flour, 11% millet flour. Compared to the wheat noodles, the multigrain noodles had higher content in fat, dietary fiber and total resistant starch, but it did content less proteins than wheat noodles.展开更多
This paper studies the;complexity of multighd mpllelization on message PaSsing computers. Parallelization is by domain decomposition. An optimal strip decomposition is proposed. With natural ordering of the grid point...This paper studies the;complexity of multighd mpllelization on message PaSsing computers. Parallelization is by domain decomposition. An optimal strip decomposition is proposed. With natural ordering of the grid points,the strip decomposition leads to good processor utilization. The efficiency could be significantly improved. Better performances could be achieved by making use of Van der Vorst ordering.展开更多
Recent advances in experimental techniques and data processing allow in situ determination of mineral crystal structure and chemistry up to Mbar pressures in a laser-heated diamond anvil cell(DAC),providing the fundam...Recent advances in experimental techniques and data processing allow in situ determination of mineral crystal structure and chemistry up to Mbar pressures in a laser-heated diamond anvil cell(DAC),providing the fundamental information of the mineralogical constitution of our Earth's interior.This work highlights several recent breakthroughs in the field of high-pressure mineral crystallography,including the stability of bridgmanite,the single-crystal structure studies of post-perovskite and H-phase as well as the identification of hydrous minerals and iron oxides in the deep lower mantle.The future development of high-pressure crystallography is also discussed.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 50395103 and 50271057）.
文摘The phase field method has been mainly used to simulate the growth of a single crystal in the past. But polycrystalline materials predominate in engineering. In this work, a phase field model for multigrain solidification is developed, which takes into account the random crystallographic orientations of crystallites and preserves the rotational invariance of the free energy. The morphological evolution of equiaxial multigrain solidification is predicted and the effect of composition on transformation kinetics is studied. The numerical results indicate that due to the soft impingement of grains the Avrami exponent varies with the initial melt composition and the solidification fraction.
基金the National Natural Science Foundation of China (41574080 and U1530402).
文摘The lower mantle makes up more than a half of our planet’s volume. Mineralogical and petrological experiments on realistic bulk compositions under high pressure–temperature (P–T) conditions are essential for understanding deep mantle processes. Such high P–T experiments are commonly conducted in a laser-heated diamond anvil cell, producing a multiphase assemblage consisting of 100 nm to submicron crystallite grains. The structures of these lower mantle phases often cannot be preserved upon pressure quenching;thus, in situ characterization is needed. The X-ray diffraction (XRD) pattern of such a multiphase assemblage usually displays a mixture of diffraction spots and rings as a result of the coarse grain size relative to the small X-ray beam size (3–5 lm) available at the synchrotron facilities. Severe peak overlapping from multiple phases renders the powder XRD method inadequate for indexing new phases and minor phases. Consequently, structure determination of new phases in a high P–T multiphase assemblage has been extremely difficult using conventional XRD techniques. Our recent development of multigrain XRD in high-pressure research has enabled the indexation of hundreds of individual crystallite grains simultaneously through the determination of crystallographic orientations for these individual grains. Once indexation is achieved, each grain can be treated as a single crystal. The combined crystallographic information from individual grains can be used to determine the crystal structures of new phases and minor phases simultaneously in a multiphase system. With this new development, we have opened up a new area of crystallography under the high P–T conditions of the deep lower mantle. This paper explains key challenges in studying multiphase systems and demonstrates the unique capabilities of high-pressure multigrain XRD through successful examples of its applications.
文摘In order to improve the nutritional quality of biscuits, a multigrain premix (MGP) was developed by using whole barley, sorghum, chickpea, pea and defatted soya flour, each at 20% level. The developed MGP had 26.28% protein, 10.13% insoluble dietary fiber and 7.38% soluble dietary fiber. The experiment was designed to optimise the MGP and wheat flour concentration for the development of multigrain biscuits with high protein, dietary fibre and to maximize the acceptability by the application of central composite rotatable design (CCRD) of Response Surface Methodology (RSM). The levels of incorporation of MGP and wheat flour were taken as variables whereas protein, soluble, insoluble fibers, biscuit dough hardness, breaking strength and overall acceptability (OAA) as responses. The optimum level of MGP and wheat flour obtained using numerical optimization was found to be 40 g and 60 g respectively. The biscuits prepared using these had 16.61% protein, 2.57% soluble fibre, and 6.67% insoluble fibre which is significantly (p ≤ 0.05) higher than control biscuit.
基金Supported by National Natural Science Foundation of China(31401642)
文摘Multigrain noodles were made by corn and wheat flour as the main ingredients and with small ratios of oat flour, soybean flour and millet flour through extrusion process. Simplex centroid design was used to analyze gelatinization characteristics of the mixed flour, rheological characteristics of the doughs, cooking qualities and sensory qualities of noodles. A proper formula for multigrain noodles obtained as outcome: 45% corn flour, 40% wheat flour, 4% oat flour, 11% millet flour. Compared to the wheat noodles, the multigrain noodles had higher content in fat, dietary fiber and total resistant starch, but it did content less proteins than wheat noodles.
文摘This paper studies the;complexity of multighd mpllelization on message PaSsing computers. Parallelization is by domain decomposition. An optimal strip decomposition is proposed. With natural ordering of the grid points,the strip decomposition leads to good processor utilization. The efficiency could be significantly improved. Better performances could be achieved by making use of Van der Vorst ordering.
基金The authors acknowledge the support from the Foundation of President of China Academy of Engineering Physics(Grant No:201402032)National Natural Science Foundation of China(Grant No:41574080 and U1530402).
文摘Recent advances in experimental techniques and data processing allow in situ determination of mineral crystal structure and chemistry up to Mbar pressures in a laser-heated diamond anvil cell(DAC),providing the fundamental information of the mineralogical constitution of our Earth's interior.This work highlights several recent breakthroughs in the field of high-pressure mineral crystallography,including the stability of bridgmanite,the single-crystal structure studies of post-perovskite and H-phase as well as the identification of hydrous minerals and iron oxides in the deep lower mantle.The future development of high-pressure crystallography is also discussed.
