The effect of electromagnetic bulging on the fatigue behavior of the5052aluminum alloy was investigated throughtensile-tensile fatigue testing.The intriguing finding is that the bulged specimens exhibited enhanced fat...The effect of electromagnetic bulging on the fatigue behavior of the5052aluminum alloy was investigated throughtensile-tensile fatigue testing.The intriguing finding is that the bulged specimens exhibited enhanced fatigue strength as depicted bymaximum stress vs the number of cycles until failure(S-N)curves,by comparison with these original aluminum alloys.Althoughthe fatigue process of the original and budged alloys follows the same mechanism with three distinct steps,namely,crack initiation ata corner of the tested samples,stable crack propagation with typical fatigue striations and finally catastrophic fracture with dimplefractographic features.The typical crack propagation rate vs stress intensity factor range(da/dN-ΔK)curves derived from thespacing of striations reveal a lower crack propagation rate in the bulged specimens.The enhancement of fatigue strength inelectromagnetically bulged aluminum alloy is further rationalized in-depth on the basis of strain hardening and dislocation shieldingeffect.展开更多
Based on a classical Heisenberg lattice model with dipole-dipole interaction and the method of spin dynamic simulation, the magnetic configurations (MC), hysteresis loops (HL) and magnetic resistance (MR) of the nanom...Based on a classical Heisenberg lattice model with dipole-dipole interaction and the method of spin dynamic simulation, the magnetic configurations (MC), hysteresis loops (HL) and magnetic resistance (MR) of the nanomagnets with different geometries, such as circle, square and rectangle, are studied for different directions of applied field. In the case of perpendicular field to the plane, the magnetization and MR are reversible and have not hysteresis. When the field is applied in the plane, the HL is irreversible and is qualitatively well agreeable with the current experimental results. The MR loop is also irreversible and appears two peaks distributed at two sides around zero field. The peaks of magnetic resistance are relative to the vortex state or similar configuration. Large easy-axis anisotropy will suppress the MC anisotropy, and the large magnetoresistance effect disappears.展开更多
The c-axis charge transport of the hole doped triangular antiferromagnet is investigated within the t-J model by considering the incoherent interlayer hopping. It is shown that the c-axis charge transport of the hole ...The c-axis charge transport of the hole doped triangular antiferromagnet is investigated within the t-J model by considering the incoherent interlayer hopping. It is shown that the c-axis charge transport of the hole doped triangular antiferromagnet is essentially determined by the scattering from the in-plane fluctuation. The c-axis conductivity spectrum shows a low-energy peak and the unusual high-energy broad band, while the c-axis resistivity is characterized by a crossover from the high temperature metallic-like behavior to the low temperature insulating-like behavior, which is qualitatively consistent with those of the hole doped square lattice antiferromagnet.展开更多
To wirelessly obtain the accurate location and orientation of an objective and exert an appropriate guidance for the objective, a feasible approach is to enclose a small rectangular permanent mag- net in the objective...To wirelessly obtain the accurate location and orientation of an objective and exert an appropriate guidance for the objective, a feasible approach is to enclose a small rectangular permanent mag- net in the objective. The magnetic field, produced by the rectangular magnet can be detected by magnetic sensors outside the objective. With these sensor data, the 3D localization and 3D orienta- tion parameters can be computed based on the mathematic model of the rectangular magnet magnetic field. In this 6D localization and orientation system, we first obtain 5D parameters of the objective by dipole model, then based on these parameters we can obtain 6D parameters by the model of rectangular magnet magnetic field using the particle swarm optimization （PSO） algorithm. Simulation experiments show that the proposed approach achieves ~ood performance.展开更多
^15N-labelled phenolic polymers were synthesized by reactions of p-benzoquinone and 1,4-diphenol with ^15N-labelled glycine and were studied by using ^15N CP-MAS NMR technique in combination with chemical approaches.R...^15N-labelled phenolic polymers were synthesized by reactions of p-benzoquinone and 1,4-diphenol with ^15N-labelled glycine and were studied by using ^15N CP-MAS NMR technique in combination with chemical approaches.Results showed that the proportion of polymer nitrogen as N-phenyl amino acid N was not as great as expected,only accounting for 5%-15%;and most of N in polymers occurred in the forms of amide,pyrrole-and indole-like nitrogen,aliphatic amines and isonitrile.It seems that great differences existed between synthetic humic acids and soil humic acids in the type and distribution of nitrogen forms.展开更多
基金Project(2011CB012806) supported by the National Basic Research Program of China
文摘The effect of electromagnetic bulging on the fatigue behavior of the5052aluminum alloy was investigated throughtensile-tensile fatigue testing.The intriguing finding is that the bulged specimens exhibited enhanced fatigue strength as depicted bymaximum stress vs the number of cycles until failure(S-N)curves,by comparison with these original aluminum alloys.Althoughthe fatigue process of the original and budged alloys follows the same mechanism with three distinct steps,namely,crack initiation ata corner of the tested samples,stable crack propagation with typical fatigue striations and finally catastrophic fracture with dimplefractographic features.The typical crack propagation rate vs stress intensity factor range(da/dN-ΔK)curves derived from thespacing of striations reveal a lower crack propagation rate in the bulged specimens.The enhancement of fatigue strength inelectromagnetically bulged aluminum alloy is further rationalized in-depth on the basis of strain hardening and dislocation shieldingeffect.
文摘Based on a classical Heisenberg lattice model with dipole-dipole interaction and the method of spin dynamic simulation, the magnetic configurations (MC), hysteresis loops (HL) and magnetic resistance (MR) of the nanomagnets with different geometries, such as circle, square and rectangle, are studied for different directions of applied field. In the case of perpendicular field to the plane, the magnetization and MR are reversible and have not hysteresis. When the field is applied in the plane, the HL is irreversible and is qualitatively well agreeable with the current experimental results. The MR loop is also irreversible and appears two peaks distributed at two sides around zero field. The peaks of magnetic resistance are relative to the vortex state or similar configuration. Large easy-axis anisotropy will suppress the MC anisotropy, and the large magnetoresistance effect disappears.
文摘The c-axis charge transport of the hole doped triangular antiferromagnet is investigated within the t-J model by considering the incoherent interlayer hopping. It is shown that the c-axis charge transport of the hole doped triangular antiferromagnet is essentially determined by the scattering from the in-plane fluctuation. The c-axis conductivity spectrum shows a low-energy peak and the unusual high-energy broad band, while the c-axis resistivity is characterized by a crossover from the high temperature metallic-like behavior to the low temperature insulating-like behavior, which is qualitatively consistent with those of the hole doped square lattice antiferromagnet.
文摘To wirelessly obtain the accurate location and orientation of an objective and exert an appropriate guidance for the objective, a feasible approach is to enclose a small rectangular permanent mag- net in the objective. The magnetic field, produced by the rectangular magnet can be detected by magnetic sensors outside the objective. With these sensor data, the 3D localization and 3D orienta- tion parameters can be computed based on the mathematic model of the rectangular magnet magnetic field. In this 6D localization and orientation system, we first obtain 5D parameters of the objective by dipole model, then based on these parameters we can obtain 6D parameters by the model of rectangular magnet magnetic field using the particle swarm optimization （PSO） algorithm. Simulation experiments show that the proposed approach achieves ~ood performance.
基金Project supported by the National Natural Science Foundation of China.
文摘^15N-labelled phenolic polymers were synthesized by reactions of p-benzoquinone and 1,4-diphenol with ^15N-labelled glycine and were studied by using ^15N CP-MAS NMR technique in combination with chemical approaches.Results showed that the proportion of polymer nitrogen as N-phenyl amino acid N was not as great as expected,only accounting for 5%-15%;and most of N in polymers occurred in the forms of amide,pyrrole-and indole-like nitrogen,aliphatic amines and isonitrile.It seems that great differences existed between synthetic humic acids and soil humic acids in the type and distribution of nitrogen forms.
