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991.
W. Chen R. Rocquet J. Burie D. Boucher 《International Journal of Infrared and Millimeter Waves》1997,18(1):217-232
A submillimeter-wave/far-infrared (SMM/FIR) laser sideband heterodyne spectrometer has been built for molecular rotational
spectroscopy application in the frequency range of 600–3000 GHz. Based on Gaussian optics, optical system of the spectrometer
is designed to be quasi-achromatic and low losses. In this article the optical design and the performance of the spectrometer
are presented. 相似文献
992.
Mechanical arrestors are frequently used in gas transmission pipelines to prevent the possibility of long running cracks. These arrestors have the effect of reducing the pipe from opening as the crack passes. This decreases the available crack driving force and, as a result, crack arrest may take place. This essentially is a second line of defence against catastrophic failure in the event crack initiation cannot always be prevented. A novel analyzing method presented in this paper has been developed to investigate the suitability of these crack arrestors. This is based on a fluid/structure/fracture interaction package, PFRAC. A dynamic finite element approach has been developed for a three dimension curved beam with initial plane curvature, which has been implemented in PFRAC to simulate the behaviour of the arrestor. The contact conditions between the pipe wall and the arrestor, along with the various computational procedures, are described. Several numerical results for a cracked pipe with arrestors are presented and compared with those for pipes without arrestors. 相似文献
993.
R.V. Shpanchenko M.G. Rozova A.M. Abakumov E.I. Ardashnikova M.L. Kovba S.N. Putilin E.V. Antipov O.I. Lebedev G. Van Tendeloo 《Physica C: Superconductivity and its Applications》1997,280(4):3652-280
Bulk superconductivity with Tc up to 94 K has been induced by fluorination of non-superconducting YBa2Cu3O6.11 using XeF2 as a fluorination agent. Strong changes on X-ray patterns were found after fluorination of reduced YBCO. High resolution electron microscopy of superconducting samples showed the presence of a new phase with c ≈ 13 Å which exists as noticeable areas included within a matrix of the 123 structure or which occurs as isolated defects with a limited extension. All fluorinated compounds exhibited a strong disorder along the c-direction resulting in a ‘loss’ of c-parameter on X-ray patterns. The present results demonstrate that fluorine indeed enters the YBCO structure with a significant structural rearrangement for the high level of fluorination. The structure of the fully fluorinated YBa2Cu3O6F2 phase, possibly responsible for superconductivity, has been deduced from high resolution electron microscopy. 相似文献
994.
995.
钢筋混凝土梁截面加固承载力分析 总被引:1,自引:0,他引:1
针对钢筋混凝土梁的截面加固问题进行了深入的受力分析,明确地论证了加固结构的受力性能与未经加固的普通结构有着显著的差别,并提供了计算公式。 相似文献
996.
Ba2MgGe2O7:Cr4+晶体中荷移激发态对g因子贡献的研究 总被引:1,自引:1,他引:0
文章建立了立方四面体3d2络合物g因子的完全高阶微扰公式.在这个公式中,除了与d-d跃迁光谱(晶场激发态)有关的晶场(CF)机制的贡献(包括近年发展的双旋-轨耦合参量模型)外,与电荷转移光谱(荷移激发态)有关的荷移(CT)机制的贡献也被考虑.将这个公式应用于Ba2MgGe2O7:Cr4 晶体平均g因子的计算,发现理论计算值与实验值很好的一致,同时,荷移机制对g移动△g(=g-2.002 3)的贡献△gCT在符号上与晶场机制的贡献△gCF相反,而在大小上约为晶场机制贡献的38%.因此,在对高价态过渡金属离子络合物的g因子计算时应考虑CF机制和CT机制的贡献. 相似文献
997.
This paper overviews the work made by our group during the past 10–15 years on crystalline systems, semiconductor surfaces,
molecular complexes and on materials of interest for technological applications, such as the defective silicon or the novel
generation thermoelectric materials. Our main aim of extracting chemical insight into the analysis of electron densities and
computed wave functions is illustrated through a number of examples. The recently proposed Source Function analysis is reviewed
and a few of its more interesting applications are summarized. Software package developments, motivated by the need of a direct
comparison with experiment or by the help these packages can provide for interpreting complex experimental outcomes, are described
and future directions outlined. A particular emphasis is given to the TOPOND and TOPXD programs, which enable one to analyze
theoretical and experimental crystalline densities using the rigorous framework of the Quantum Theory of Atoms in Molecules,
due to Bader. 相似文献
998.
双离子束溅射淀积DLC膜的红外特性 总被引:1,自引:0,他引:1
用双离子束溅射法在50℃以下的玻璃基片上淀积了类金刚石碳(DLC)膜.研究了轰击离子能量、轰击离子束流密度及轰击源内氢/氩流量比例对淀积片红外透射特性的影响.所用波段是1.5~5.5μm.结果表明,对所有淀积样片,其相对透过率均随波长增长而增大.在每组实验中,随如上各可变参量的增大,各样片的相对透过率~波长曲线均有先上升后下降的规律.确定了各组相应的临界参数.结果还表明,轰击源不含氢并不影响DLC膜的制取,但轰击源合氢时所制得的膜具有更好的红外透射性.从结构变化的角度解释了上述规律. 相似文献
999.
1000.