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821.
为了研究浸没式浮筒对悬链线系泊缆松弛-张紧特性的影响,本文基于集中质量法建立了下端锚固、上端做简谐运动的带浮筒悬链线系缆运动微分方程。运用Newton-Raphson法和Howbolt差分法,求解了系缆的运动特性和动张力值。通过与无浮筒悬链线系泊系统的对比,分析了几种不同参数的浮筒对系泊缆松弛-张紧现象及冲击放大系数两个方面的影响。结果表明:附加一定大小的浸没式浮筒能有效抑制系泊缆松弛-张紧现象的出现,并且减小系缆运动过程中动张力的冲击放大系数;但当附加浮筒的净浮力过大时,在极端海况下,会助长系泊缆上端出现松弛-张紧现象,进而影响系泊物的稳定性。 相似文献
822.
823.
锚固体的受力特征及其影响因素是锚固体设计的重要依据,直接影响锚固效果。传统的经典弹性理论没有考虑应变梯度的影响。偶应力理论引进弯曲曲率,考虑了弯曲效应对介质变形特性的影响。基于偶应力理论,建立了平面应变问题的有限元计算模型,研究锚固体锚固段界面上的剪应力分布、锚固体轴力分布、偶应力的尺度效应以及弹性模量和围压对锚固力的影响,并将偶应力理论的计算结果和经典弹性理论的计算结果进行了比较。结果表明,在偶应力理论下,锚固体锚固段界面的剪应力有所减小,特别是峰值处的剪应力减小明显;岩土的弹性模量越大,锚固界面局部剪应力越大;锚固力随着围压的增大而增大,偶应力尺度效应明显。 相似文献
824.
Ibrahim A. Abbas 《基于设计的结构力学与机械力学》2015,43(4):501-513
The model of generalized thermoelasticity proposed by dual phase lag (DPL), is applied to study the thermoelastic interactions in an infinite fiber-reinforced anisotropic medium with a circular hole. A decaying with time thermal field on the boundary of the hole, which is stress free, causes the thermoelastic interactions. The solutions for displacement, temperature, and stresses are obtained with the help of the finite element procedure. The effects of the reinforcement on temperature, stress, and displacement are studied. The exact solution in the case of isotropic medium is discussed explicitly. The accuracy of the finite element method validated by comparing between the finite element and exact solutions for absence the reinforcement. 相似文献
825.
Anna A. Hoser Paulina M. Dominiak Krzysztof Wo
niak 《Acta Crystallographica. Section A, Foundations and Advances》2009,65(4):300-311
The consequences of different treatments of H atoms in experimental charge‐density studies are discussed. Geometric and topological parameters obtained after applying four different H‐atom models in multipolar refinement on high‐resolution X‐ray data only were compared with the results obtained for a reference joint high‐resolution X‐ray/neutron refinement. The geometry and the topological critical point and integrated parameters closest to the reference values were obtained after a mixed refinement (high‐order refinement of heavy atoms, low‐angle refinement of H atoms and elongation of the X—H distance to the average neutron bond lengths) supplemented by an estimation of the anisotropic thermal motions of H atoms using the SHADE program. Such a procedure works very well even for strong hydrogen bonds. The worst fit to the reference results for both critical point and integrated parameters was obtained when only the standardization to the average neutron X—H distances was applied. The non‐H‐atom parameters are also systematically influenced by the H‐atom modeling. In order to compare topological and integrated properties calculated for H and non‐H atoms in multipolar refinement when there are no neutron data, the same treatment of H atoms (ideally the mixed refinement + estimated anisotropic atomic displacement parameters for H atoms) should be applied. 相似文献
826.
F. Kyriazis A. Chrissanthopoulos V. Dracopoulos M. Krbal T. Wagner M. Frumar S.N. Yannopoulos 《Journal of Non》2009,355(37-42):2010-2014
We report on the structural details and microphase separation of the bulk glasses Agx·(As33S67)100-x for 0x25. Glass–glass phase separation occurs over a wide range of Ag content, i.e. 4x20. An off-resonant polarized Raman spectroscopic study has been carried out to elucidate structural aspects at the short- and medium-range structural order of the glasses. Analysis of Raman spectra revealed quantitative changes of the sulfur-rich microenvironments that reduce upon adding Ag. Scanning electron microscopy combined with X-rays microanalysis have been utilized to examine the type and extent of phase separation, and to provide quantitative details on the atomic concentrations in the Ag-poor and Ag-rich phases. It has been shown that at 7 at.% Ag the Ag-rich phase percolates through the structure; this effect can be associated with an ionic-to-superionic behavior of these glasses in accordance with similar studies on the stoichiometric arsenic sulfide glass; although the phase separation observed in the present glasses is qualitatively different. 相似文献
827.
In the present paper, single‐crystalline lanthanum orthovanadate (LaVO4) nanorods were synthesized by an ethylenediaminetetraacetic acid (EDTA)‐mediated hydrothermal method. The resulting products were characterized using XRD, SEM, TEM and HRTEM. The experimental results illustrated that the morphologies and microstructures of LaVO4 nanorods were influenced by EDTA and pH value of the precursor solution. The magnetic properties measurements showed that the magnetocrystalline anisotropy was greatly strengthened by the strong effect of the one‐dimensional anisotropy, and the magnetic properties of LaVO4 nanorods are better than that of LaVO4 nanoparticles. The growth mechanism of LaVO4 nanorods was also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
828.
Takahiro Yamada Hisanori Yamane Takaaki Ohta Takenari Goto Takafumi Yao 《Crystal Research and Technology》2007,42(1):13-17
GaN crystals were prepared by heating a Ga melt with 1 at% Li3N against Ga at 750 °C in Na vapor under N2 pressures of 0.4–1.0 MPa. The GaN crystals grown at 1.0 MPa of N2 were colorless and transparent prismatic, having a size of approximately 0.7 mm in length. A secondary ion mass spectrometry (SIMS) showed the contaminant of lithium in the obtained crystals. A large broad yellow band emission peak of 2.28 eV was observed at room temperature in the photoluminescence spectrum in addition to the near band emission peak of GaN at 3.39 eV and a small broad satellite emission at 3.24 eV. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
829.
Y. Huang B. J. Zhao S. F. Zhu W. L. Zhu C. F. Xu S. Q. Wan Z. Y. He 《Crystal Research and Technology》2007,42(3):227-230
High‐pure and single‐phase AgGa1‐xInxSe2 (x=0.2) polycrystalline was synthesized by the mechanical and temperature oscillation method. Adopting the modified Bridgman method an integral AgGa1‐xInxSe2 single crystal with diameter of 14 mm and length of 35 mm has been obtained at the rate of 6 mm/day. It was found that there is a new cleavage face which was (101), and observed the four order X‐ray spectrum of the {101} faces. By the method of DSC analysis the melting and freezing points of the AgGa1‐xInxSe2 (x=0.2) single crystal were about 828°C and 790°C. The transmission spectra of the AgGa1‐xInxSe2 (x=0.2) sample of 5×6×2 mm3 were obtained by means of UV and IR spectrophotometer. The limiting frequency was 774.316nm and the band gap was 1.6eV. It can be found in the infrared spectrum that the infrared transmission was above 60% from 4000cm‐1 to 600cm‐1. The value of α in 5.3µm and 10.6µm were 0.022cm‐1 and 0.1cm‐1 respectively. All results showed that the crystal was of good quality. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
830.