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This paper studies the effects of Ag atomic segregation from the inner (100) or (111) planes on the melting of Ag-Pd clusters with different sizes by a molecular dynamics simulation. The results show that Ag segregation leads to the atomic energy decreases with increasing the temperature. Furthermore, the effect of the (100) segregation is larger than that of the (111) segregation. Meanwhile, the influence of segregation on the energy decreases with increasing the cluster size. The melting points of the clusters without segregation are the largest, followed by the clusters with a (111) and (100) segregation. [ABSTRACT FROM AUTHOR]

Several samples of Zn-Sb alloys, composed with β-ZnSb and Zn phases, were prepared by solidification under high magnetic fields (HMFs). The microstructure evolution and thermoelectric (TE) properties of the alloys were then investigated. Zn phase precipitated as strip and presented reticulation structure in the samples without HMFs. When the HMFs were imposed, Zn became disperse and the strip of Zn became thinner and shorter. In addition, the c-axis of Zn crystals showed a tendency to orientate toward the direction perpendicular to the magnetic field direction. The samples prepared under HMFs had higher resistivity and Seebeck coefficient and lower thermal conductivity. When compared to the solidified samples without HMFs, the application of 8.8 T of HMF increased the maximum figure of merit 3.7 times. In addition, the relationship between microstructure and TE properties was also analyzed. [ABSTRACT FROM AUTHOR]

The nanocrystalline FeNi thin films were prepared by molecular-beam-vapor deposition under different magnetic flux densities. The microstructure and magnetic properties of thin films were examined by AFM, TEM, HRTEM and VSM. The results show that with the increase of magnetic flux densities, the changing trend of the average particle size is the same as the coercive force except 6 T. Under 6 T condition, the thin film became the mixture of bcc and fcc phases, which leads to slight increase of the coercive force. In addition, the HRTEM result shows the short-range ordered clusters (embryos) or nucleation rate of thin films increase with increasing magnetic flux densities. [ABSTRACT FROM AUTHOR]

The influence of static magnetic field of 4 T on electroless Ni-P deposition process and post-annealing was investigated in this study. The results from differential scanning calorimeter have shown that the imposed high magnetic field during electroless deposition had a further beneficial effect on defects migration and annihilation after Ni-P alloys heated at around 250 °C. Furthermore, it is found that some metastable phases were presented after magnetic annealing at 300 °C (below crystallization temperature), and the hardness of magnetic-annealed Ni-P alloys was greater than that of conventionally annealed Ni-P alloys. The morphology of the Ni-P alloys was characterized by scanning electron microscope, and shows typical spherical nodular structure for the as-deposited Ni-P alloys. The boundaries of these spherical nodular crystals blurred after annealing; however, the boundaries were apparently observed after magnetic annealing at 300 °C. [ABSTRACT FROM AUTHOR]

This paper studies the melting of Ag-Pd bimetallic clusters with different Ag concentrations and atomic distributions by using molecular dynamics simulation with a general embedded-atom method. The melting of a cluster with 45 % Ag atoms distributing in the core was compared with that of 45 %, 15 % Ag on the surface and 15 % Ag in the core. It is found that the energy variation with the increasing temperature is strongly related to the Ag atomic segregation, due to the reason that there is a competition between the decreased energy induced by the atomic segregation and the increased energy as the temperature increases. The melting of the Ag-core clusters with different Ag concentrations from 5 to 55 % Ag was further explored. It is found that the irregular variation of energy occurred that the atomic energy increases, keeps unchanged or decreases with the increase of the temperature. Furthermore, the irregular phenomena of the melting were induced by the Ag concentrations. This gives a new method to tune the melting in bimetallic clusters. [ABSTRACT FROM AUTHOR]

The effects of an 11.5 T high magnetic field on the growth behavior of compounds layers during reactive diffusion in solid Al/solid Mg diffusion couples have been investigated. After annealing with and without a magnetic field, the interfacial zone was still composed of two layers of stable compounds β (MgAl) and γ (MgAl), but the thicknesses of the layers were increased by the magnetic field. Data analysis of the thicknesses of compound layers showed that the growth of the γ layer was controlled by grain boundary diffusion as well as volume diffusion at B=0 T, but only controlled by volume diffusion when an 11.5 T high magnetic field was applied. The interdiffusion coefficients for the samples annealed at 643-693 K were calculated from the parabolic relationship between the migration of the interface and the annealing time. The results show that the diffusion constant increased due to the high magnetic field, increasing the chemical potential gradient, and in turn it caused the interdiffusion coefficient to increase. [ABSTRACT FROM AUTHOR]

A mechanical analysis is done to find the evolution of the interface profile between binary immiscible fluids induced by a three-dimensional orthogonal magnetic field gradient. In the experiments, the changes of the interface profile between four groups of binary immiscible fluids are investigated under the same horizontal magnetic field gradients. The binary immiscible fluids are made of benzene and other liquids, like CuSO, Fecl, FeSO or Cucl aqueous solutions. In addition, the interface profile between the benzene and CuSO aqueous solution is examined under different horizontal magnetic field gradients. The experimental results are consistent with the theoretical analysis. This study explains the enhanced Moses effect from a mechanics standpoint. Furthermore, a new method for susceptibility measurement is proposed based on this enhanced Moses effect. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulation with the embedded atom method was applied to study the melting and coalescence in the mixed Cu-Ni nanoclusters. The validity of the model was tested by examining the consistency of the phase diagrams of the (CuNi) and (CuNi) clusters with the Cu-Ni bulk. The coalescences of two mixed Cu-Ni clusters and a pure Cu cluster with a pure Ni cluster were simulated. The coalesced temperature T forming a liquid complex and melting temperature T of the cluster with the same size were compared. The results indicate that T is higher than T for the coalescences of both (CuNi) and (CuNi) clusters. The analysis of the relationship between the Cu-Ni bond content and T indicates that the formation of the Cu-Ni bonds contributes a lot to the phenomenon. [ABSTRACT FROM AUTHOR]

Mn-90.8 wt%Sb alloys were solidified without and with high magnetic fields to investigate the effects of high magnetic fields on the structure evolution of the alloys. It was found that there were only MnSb/Sb eutectics without any primary phase in the alloy at 0 T, whereas a small amount of primary MnSb dendrites appeared in the MnSb/Sb eutectic matrix when the magnetic flux density was 4.4 T. In magnetic fields of 6.6, 8.8, and 11.5 T, both of two primary phases, i.e., MnSb and Sb, occurred in the matrix. In addition, the volume fraction of these two primary phases increased with increasing magnetic flux density. In magnetic fields of 8.8 and 11.5 T, primary MnSb dendrites aligned parallel to the magnetic field direction and gathered at the edge of the specimens. In contrast, primary Sb dendrites gathered in the center region of the specimens. [ABSTRACT FROM AUTHOR]

This study is concerned with the investigation of the structural evolution occurring during isothermal annealing of an Mn-89.7 wt%Sb alloy in a high magnetic field in the semisolid state. The alloy specimens were isothermally annealed without and with an 11.5-T magnetic field for various annealing times. With the application of the magnetic field, the average characteristic radius of the primary MnSb particles increased with increasing annealing time. The primary MnSb particles were oriented with their c-plane parallel to the imposed field direction. Furthermore, the primary MnSb particles were found to align along the field direction and form chainlike structures eventually. These phenomena were attributed to the attraction and coalescence of the particles induced by the dipole–dipole interactions among them. [ABSTRACT FROM AUTHOR]

Al-Ni hypereutectic alloys with various compositions were solidified under various magnetic field conditions to investigate the alignment of primary Al3Ni phases. The results showed that the application of high magnetic fields could improve the homogeneity of the primary Al3Ni phase distribution and induce the alignment of primary Al3Ni phases in the direction perpendicular to the magnetic field direction to form chain-like structures. However, the alignment was different from the orientation of the Al3Ni phases. Furthermore, the degree of the alignment decreased with the increasing concentration of Ni element. This can be attributed to the combination effects of high magnetic field and alloy composition on the concentration field around the crystallized primary Al3Ni crystals. [ABSTRACT FROM AUTHOR]

Using five well-replicated Qilian juniper (Sabina przewalskii Kom.) tree-ring width index series, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982 to 2001, the relationships between tree-ring width index, NDVI of grassland, and climatic data were analyzed firstly. Then, the relationship between tree-ring width index and NDVI of grassland was explored. The results showed that: (1) Temperature and precipitation in June influenced tree-ring width index and NDVI of grassland deeply in Delingha. (2) There were significant relationships between five tree-ring width index series (DLH1-DLH5) and monthly NDVI of grassland from June to September, with the most significant relationship being between tree-ring width index series and NDVI of grassland in August. (3) The PC1 (the first principal component derived from DLH1-DLH5 series) exhibited good agreement with monthly NDVI of grassland in the grass growth season (from June to September) and the averaged NDVI in the growth season, which was attributed to their common responses to water-supply limit in Delingha. This study may allow an increase in studying the past dynamics of grassland in Delingha in that the variation of grassland NDVI during the last millennium has been reconstructed from PC1. [ABSTRACT FROM AUTHOR]

A theoretical analysis for momentum and heat transfer characteristics in a steady narrow axisymmetric laminar jet is made based on the assumption of boundary layer. The types of potential flows necessary for having the similar solutions to boundary layer equations are determined and the analytical solutions are presented for both momentum and energy boundary layer equations. Some transport properties of the jets are investigated [ABSTRACT FROM AUTHOR]

The classical power law non-Newtonian fluids energy boundary layer equation is proved improper to describe the self-similar heat transfer. A theoretical analysis for momentum and energy boundary layer transfer behavior is made and the full similarity heat boundary layer equation is developed, which may be characterized by a power law relationship between shear stress and velocity gradient with the Falkner-Skan equation as a special case. Both analytical and numerical solutions are presented for momentum and energy boundary layer equations by using the similarity transformation and shooting technique and the associated transfer characteristics are discussed. [ABSTRACT FROM AUTHOR]

Analytical and numerical solutions are established for momentum and energy laminar boundary layer induced by a shock wave. The results indicated that skin friction σ decreases with increasing in velocity ratio ξ (1≤ξ<6). For each specified ξ (1≤ξ <6), temperature w( t) increases with increasing of T w but decreases with T e, and for a range of t ε [1, ξ], w( t) decreases with the increasing of t. Thermal diffusion increases with increasing of u w but decreases with increasing u e. [ABSTRACT FROM AUTHOR]

The behavior for a class of initial, boundary value problems of generalized diffusion equations was studied utilizing the similarity transformation and shooting technique. Numerical solutions are presented for k(s)=s M, exponent M=1.0 to 5.0, and power law parameter N ( N=0.3 to 3.0). The results shown that for each fixed M, the temperature distribution θ decreases with increasing in power law parameter N, and for each fixed N, the temperature distribution θ increases with the decreasing of M. [ABSTRACT FROM AUTHOR]

Performance comparisons are composed of two parts: the first part contains the systematically investigation of six difference schemes including CDS, FUDS, HDS, PLDS, SUDS and QUICK for convection terms in numerical fluid flow and heat transfer based on the finite volume method using staggered and Rhie-Chow’s momentum interpolation collocated grids, the second part contains the comparative computations being conducted on Rhie-Chow’s momentum interpolation collocated grid and Thiart’s finite difference scheme based nonstaggered grid. Three 3-D cases that have analytical or benchmark solutions are adopted. For the first part, the results of computations indicate that, all the six schemes have the same numerical accuracy when the diffusion term is predominant. With the increase of convection, the FUDS, HDS and PLDS almost have the same accuracy in two of those grid systems, while the SUDS and QUICK have higher accuracy than the former. The accuracy of CDS is something in between. For the same under-relaxation factors and convergence criterion, the convergence rate of each scheme on those two grid systems are nearly equal with that on the staggered grid being a little bit faster. For QUICK and CDS, smooth, non-oscillating solutions can be obtained even when local Peclet number may be as large as 31.2–31.3. For the second part, it is concluded that simplified collocated grid system is preferable from numerical accuracy, grid Peclet number limit, sensitivity to the under-relaxation factor and the freedom in choosing finite difference scheme for convection term. [ABSTRACT FROM AUTHOR]