We investigate the effect of impurities on the thermal entanglement in a spin-1/2 Ising-Heisenberg butterfly-shaped chain,where four interstitial Heisenberg spins are localized on the vertices of a rectangular plaquet...We investigate the effect of impurities on the thermal entanglement in a spin-1/2 Ising-Heisenberg butterfly-shaped chain,where four interstitial Heisenberg spins are localized on the vertices of a rectangular plaquette in a unit block.By using the transfer-matrix approach,we numerically calculate the partition function and the reduced density matrix of this model.The bipartite thermal entanglement between different Heisenberg spin pairs is quantified by the concurrence.We also discuss the fluctuations caused by the impurities through the uniform distribution and the Gaussian distribution.Considering the effects of the external magnetic field,temperature,Heisenberg and Ising interactions as well as the parameter of anisotropy on the thermal entanglement,our results show that comparing with the case of the clean model,in both the twoimpurity model and the impurity fluctuation model the entanglement is more robust within a certain range of anisotropic parameters and the region of the magnetic field where the entanglement occurred is also larger.展开更多
A1 doped SmFeO3 (SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05) were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit c...A1 doped SmFeO3 (SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05) were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing AI substitution in orthoferrite. The effective magnetic moment (μeff) and the Curie constant (C) were calculated from the reciprocal of the molar magnetic susceptibility (Z-1) versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, N6el temperature (TN) and spin reorientation (TsR) transitions. The M-H hysteresis loop of the parent sample took butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample;Hc=6198.80e. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spin- tronic applications.展开更多
A parametric computational study is conducted to investigate the shear yielding, flexural yielding, and lateral torsional buckling limit states for butterfly-shaped links. After validating the accuracy of the finite e...A parametric computational study is conducted to investigate the shear yielding, flexural yielding, and lateral torsional buckling limit states for butterfly-shaped links. After validating the accuracy of the finite element modeling approach against previous experiments, 112 computational models with different geometrical properties were constructed and analyzed including consideration of initial imperfections. The resulting yielding moment, corresponding critical shear force, the accumulation of plastic strains through the length of links as well as the amount of energy dissipated are investigated. The results indicate that as the shape of the butterfly-shaped links become too straight or conversely too narrow in the middle, peak accumulated plastic strains increase. The significant effect of plate thickness on the buckling limit state is examined in this study. Results show that overstrength for these links (peak force divided by yield force) is between 1.2 and 4.5, with straight links producing larger overstrength. Additionally, proportioning the links to delay buckling, and designing the links to yield in the flexural mode are shown to improve energy dissipation.展开更多
The primitive carving discovered at the Hemudu site of Yuyao, Zhejiang Province. first appeared on practical and sacrificial utensils. The utensil shown here is called. "The Double Birds Fly to the Sun." An ...The primitive carving discovered at the Hemudu site of Yuyao, Zhejiang Province. first appeared on practical and sacrificial utensils. The utensil shown here is called. "The Double Birds Fly to the Sun." An exquisitely-carved piece. it was unearthed in 1977 at Hemudu. At 16.6 cm long, 5,9 cm wide and 1.2 cm thick, its base and upper section are incomplete. On the surface of the ivory, a beautiful picture is carved in intaglio lines: A pair of concentric circles in different sizes.展开更多
The effect of cooling rate on the transition of dendrite morphology of a Mg-6Gd (wt%) alloy was semiquantitatively analyzed under a constant temperature gradient by using synchrotron X-ray radiographic technique. Re...The effect of cooling rate on the transition of dendrite morphology of a Mg-6Gd (wt%) alloy was semiquantitatively analyzed under a constant temperature gradient by using synchrotron X-ray radiographic technique. Results show that equiaxed dendrites, including exotic 'butterfly-shaped' dendrite morphology, dominate at high cooling rate (〉1 K/s). When the cooling rate decreases in the range of 0.5-1 K/s, the equiaxed-to-columnar transition takes place, and solute segregates at the center of two long dendrite arms (LDA) of the 'butterfly-shaped' dendrite. When the cooling rate is lower than 0.3 K/s, directional solidification occurs and the columnar dendritic growth direction gradually rotates from the crystalline axis to the thermal gradient direction with an increase in cooling rate. Meanwhile, interface moves faster but the dendrite arm spacing decreases. Floating, collision and rotation of dendrites under convection were also studied in this work.2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12074101)the Science Fund for the New Century Excellent Talents in University of the Ministry of Education of China(Grant No.NCET-11-0960)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20134208110001).
文摘We investigate the effect of impurities on the thermal entanglement in a spin-1/2 Ising-Heisenberg butterfly-shaped chain,where four interstitial Heisenberg spins are localized on the vertices of a rectangular plaquette in a unit block.By using the transfer-matrix approach,we numerically calculate the partition function and the reduced density matrix of this model.The bipartite thermal entanglement between different Heisenberg spin pairs is quantified by the concurrence.We also discuss the fluctuations caused by the impurities through the uniform distribution and the Gaussian distribution.Considering the effects of the external magnetic field,temperature,Heisenberg and Ising interactions as well as the parameter of anisotropy on the thermal entanglement,our results show that comparing with the case of the clean model,in both the twoimpurity model and the impurity fluctuation model the entanglement is more robust within a certain range of anisotropic parameters and the region of the magnetic field where the entanglement occurred is also larger.
文摘A1 doped SmFeO3 (SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05) were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing AI substitution in orthoferrite. The effective magnetic moment (μeff) and the Curie constant (C) were calculated from the reciprocal of the molar magnetic susceptibility (Z-1) versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, N6el temperature (TN) and spin reorientation (TsR) transitions. The M-H hysteresis loop of the parent sample took butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample;Hc=6198.80e. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spin- tronic applications.
基金This material is based upon the work supported by the National Science Foundation(Grant No.CMMI-1453960)The Advanced Research Computing(ARC)facilities at Virginia Tech provided computational resources and technical support for this project.
文摘A parametric computational study is conducted to investigate the shear yielding, flexural yielding, and lateral torsional buckling limit states for butterfly-shaped links. After validating the accuracy of the finite element modeling approach against previous experiments, 112 computational models with different geometrical properties were constructed and analyzed including consideration of initial imperfections. The resulting yielding moment, corresponding critical shear force, the accumulation of plastic strains through the length of links as well as the amount of energy dissipated are investigated. The results indicate that as the shape of the butterfly-shaped links become too straight or conversely too narrow in the middle, peak accumulated plastic strains increase. The significant effect of plate thickness on the buckling limit state is examined in this study. Results show that overstrength for these links (peak force divided by yield force) is between 1.2 and 4.5, with straight links producing larger overstrength. Additionally, proportioning the links to delay buckling, and designing the links to yield in the flexural mode are shown to improve energy dissipation.
文摘The primitive carving discovered at the Hemudu site of Yuyao, Zhejiang Province. first appeared on practical and sacrificial utensils. The utensil shown here is called. "The Double Birds Fly to the Sun." An exquisitely-carved piece. it was unearthed in 1977 at Hemudu. At 16.6 cm long, 5,9 cm wide and 1.2 cm thick, its base and upper section are incomplete. On the surface of the ivory, a beautiful picture is carved in intaglio lines: A pair of concentric circles in different sizes.
基金financially supported by the Program of Shanghai Subject Chief Engineering (No. 14XD1425000)the National Natural Science Foundation of China (No. 51304135)the Chinese Scholarship Council and DOE (No. DE-FG02-07ER46417)
文摘The effect of cooling rate on the transition of dendrite morphology of a Mg-6Gd (wt%) alloy was semiquantitatively analyzed under a constant temperature gradient by using synchrotron X-ray radiographic technique. Results show that equiaxed dendrites, including exotic 'butterfly-shaped' dendrite morphology, dominate at high cooling rate (〉1 K/s). When the cooling rate decreases in the range of 0.5-1 K/s, the equiaxed-to-columnar transition takes place, and solute segregates at the center of two long dendrite arms (LDA) of the 'butterfly-shaped' dendrite. When the cooling rate is lower than 0.3 K/s, directional solidification occurs and the columnar dendritic growth direction gradually rotates from the crystalline axis to the thermal gradient direction with an increase in cooling rate. Meanwhile, interface moves faster but the dendrite arm spacing decreases. Floating, collision and rotation of dendrites under convection were also studied in this work.2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.