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排序方式: 共有9568条查询结果,搜索用时 15 毫秒
61.
S. V. Trukhanov A. V. Trukhanov H. Szymczak C. E. Botez A. Adair 《Journal of Low Temperature Physics》2007,149(3-4):185-199
The crystal structure and magnetotransport properties of the Nd0.70Ba0.30-MnO3.00−δ
manganites have been investigated. The stoichiometric A-site ionic disordered Nd0.70Ba0.30MnO3.00 sample is orthorhombic (SG=Imma) ferromagnet below T
C
≈151 K. It has metal-insulator transition at T
MI
≈140 K and peak of magnetoresistance ∼50% in field of 9 kOe. The anion-deficient partly A-site ionic ordered Nd0.70Ba0.30MnO2.60 sample is ferrimagnet with T
N
≈130 K and has nanometric ∼440 nm grains. The oxygen annealed stoichiometric partly A-site ordered Nd0.70Ba0.30MnO3.00 sample consists of two perovskite phases: (i) A-site ionic completely ordered tetragonal (SG=P4/mmm) NdBaMn2.00O6.00 with a Curie point of ∼310 K and (ii) superstoichiometric orthorhombic (SG=Pnma) NdMnO3.00+γ
with a Curie point of ∼120 K. The magnetoresistance of this sample at the room temperature is about 7% in a field of 9 kOe.
Considerable changes of the magnetic properties are interpreted as due to the ordering of Nd3+ and Ba2+ cations as well as the formation of nanometric grains.
相似文献
62.
Techniques and Apparatus for Measuring Rotational Core Losses of Soft Magnetic Materials 总被引:1,自引:0,他引:1
In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux density vector is rotating. Therefore, the magnetic properties of the core materials under the rotating flux density vector excitation should be properly measured, modeled and applied in the design and analysis of these electromagnetic devices. This paper presents an extensive review on the development of techniques and apparatus for measuring the rotational core losses of soft magnetic materials based on the experiences of various researchers in the last hundred years. 相似文献
63.
64.
65.
本文通过建立几何模型 ,讨论了高速转镜相机光束倾斜入口的成象原理。证实了倾斜光束入口在转镜旋转时成象点的扫描轨迹是在以入射点为顶点 ,以成象点和入射点的连线为母线扫出的正圆锥底面的平面内 ,从而把空间光学的复杂设计问题简化成平面上的设计。此原理已用于 PDF- 2 0 0型平面转镜等待式分幅相机的设计 相似文献
66.
研制成功了128×128元PtsiIRCCD,获得了清晰的室温目标热像。文章叙述了该摄像机驱动逻辑电路的设计、驱动方式的研究和视频信号、数字信号的处理。 相似文献
67.
Fast Recognition of Fibonacci Cubes 总被引:1,自引:0,他引:1
Fibonacci cubes are induced subgraphs of hypercubes based on Fibonacci strings. They were introduced to represent interconnection
networks as an alternative to the hypercube networks. We derive a characterization of Fibonacci cubes founded on the concept
of resonance graphs. The characterization is the basis for an algorithm which recognizes these graphs in O(mlog n) time.
A. Vesel supported by the Ministry of Science of Slovenia under the grant 0101-P-297. 相似文献
68.
Z. Drzazga A. Winiarska W. Zarek E. Popiel L. Gladczuk 《Journal of Alloys and Compounds》1995,230(2):76-84
Carbon was introduced by arc melting into RFe12−xVx compounds, where R = Y or Dy and x = 2, 3 or 4, and its effects on the crystallographic and magnetic properties of these intermetallics were investigated by X-ray, magnetostatic and Mössbauer effect measurements. Experimental results show that the carbon atoms prefer the 4d sites to the 2b sites, or occupy the sites reserved for Fe atoms in the ThMn12-type crystal structure. Carbon solution increases with increasing vanadium concentration, giving rise to an effect opposite to that of vanadium. An increase in vanadium content causes an increase in the cell volume and a linear decrease in Curie temperature and in the Fe magnetic moment, whereas the addition of carbon leads to a reduction in unit volume while maintaining a high Tc and enhancing the Fe magnetic moment despite decreasing iron content in the samples. 相似文献
69.
为了发挥对地观测卫星在大面积、实时、快速获取地表数据方面的优势,用户需要事先掌握对于自己感兴趣区域上空的卫星过境情况和成像能力。本文通过对卫星轨道预报模型与算法、卫星地面成像区域边界轨迹计算模型和算法的探讨与实践,得到了一些对卫星成像区域仿真有益的经验。试验证明,对于无侧视情况下,使用较旧的卫星轨道根数来计算卫星成像区域,仍能满足用户对于成像区域预报的精度要求。 相似文献
70.
V Chandrasekaran Ch Sreerama Murthy P Subrahmaniam G Venkateswarlu 《Bulletin of Materials Science》1986,8(1):39-48
Iron-chromium-cobalt alloys possess attractive magnetic properties combined with good formability and hence are identified as technologically important magnetic materials. Alloys with compositions Fe-28·9 Cr-15·6 Co and Fe-28·4 Cr-20·1Co (weight percent) have been studied. Heat-treatment parameters during thermomagnetic treatment viz temperature, time and external magnetic field were optimized with reference to magnetic properties. The fully treated anisotropic alloys develop remanence=11·5–12·0 kilo Gauss, coercivity=600–650 Oersted and energy product=4–4·5 million Gauss Oersted. Electron microscopic and Mössbauer spectroscopic techniques were used to identify the original and transformed phases. During the various stages of the development of the alloy, the changes in mechanical hardness were correlated with magnetic hardness. 相似文献