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751.
752.
Agostino A. Cannarozzi Mario Cannarozzi 《International journal for numerical methods in engineering》1995,38(20):3433-3452
A scheme of boundary displacements with drilling degrees of freedom for plane elements is presented. The scheme is free from zero displacement modes and allows the development of hybrid finite elements with vertex and mid-side nodes, each node including a drilling degree of freedom besides the translational ones. Four quadrilateral isoparametric hybrid stress elements are implemented, and numerical results for some current test problems are given. 相似文献
753.
Rodrigo V. Rodrigues Łukasz Marciniak Latif U. Khan Antônio A.L. Marins Robert Tomala Emanuel J.B. Muri Jivaldo R. Matos Wiesław Strȩk 《中国稀土学报(英文版)》2019,37(11):1164-1169
Rare earth(Ⅲ) diphenyl-4-amine sulfonates(RE(DAS)_3·xH_2O,RE=Eu~(3+),Tb~(3+))phosphors were synthesized by precursor method from barium diphenyl-4-amine sulfonate and rare earth sulfates.FTIR,TG/DSC coupled to mass spectrometry(TG/DSC/MS),X-ray powder diffraction(XPD),scanning electron microscopy(SEM) and photo luminesce nce(PL) spectroscopy were utilized to structurally and morphologically characterize the samples.Thermal decomposition of Eu(DAS)_3·7H_2O and Tb(DAS)_3·2H_2O at 973 K under dynamic air atmosphere results in crystalline Eu_2O_2SO_4 and Tb_2O_2SO_4 materials,respectively.Accordingly,MS spectra reveal the liberation of thermal decomposition products of precursors,largely as CO_2,NO_2 and SO_2 gases.The diphenyl-4-amine sulfonate(DAS) ligand demonstrats a good stabilizing property for Eu~(3+) and Tb~(3+) ions.The Eu(DAS)_3·7H_2O and Tb(DAS)_3·2H_2O compounds display efficient red and green emissions,under UV excitation,arising from the ~5D_0→~7F_J(J=0-4) and ~5D_4→~7F_J(J=0-6) transitions of the Eu~(3+) and Tb~(3+) ions,respectively. 相似文献
754.
分别采用液-固和液-液掺杂方式向钼粉中引入氧化镧,用粉末冶金方法烧结出Mo合金。通过透射电镜和扫描电镜研究了不同掺杂方式制备的Mo—La2O3材料中第二相颗粒的粒度分布、形貌,以及钼合金的断口形貌。试验结果表明液-液掺杂方法有利于细化、分散La2O3;液-液掺杂试样的断裂韧性优于液-固掺杂试样。并通过位错塞积理论讨论了La2O3的粒度分布对钼合金性能的影响。 相似文献
755.
《TEST》1982,33(2):64-78
Summary Several new criteria are proposed for the determination of suitable sample size for assessing the statistical tolerance limits.
The application of the criteria is illustrated on the solution of some problems from the theory of errors and theory of reliability.
Resumen En este trabajo se proponen algunos nuevos criterios que tratan de fijar el tama?o de la muestra necesario para establecer los límites estadísticos de tolerancia. Como aplicación de estos criterios se resuelven algunos problemas de la teoría de los errores y de la teoría de la confiabilidad.相似文献
756.
本文回顾了2003圣保罗国际建筑与设计双年展,阐述了本次展览“大都市”主题的内涵和意义。 相似文献
757.
合成了硝酸钍与双希夫碱邻香草醛缩邻苯二胺的新固体配合物。通过元素分析、红外光谱、紫外光谱、差热-热重及摩尔电导分析等手段,确定配合物的组成为ThL(NO3)4,研究了它的配位方式和某些物理化学性质。 相似文献
758.
Magnetic Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles were prepared by a novel and simple method: anthranilic acid assisted polymerization. The synthetic strategy involved two steps. First, Fe3O4 nanoparticles capped by anthranilic acid were obtained by a chemical precipitation method, and then the aniline and oxidant were added to the modified Fe3O4 nanoparticles to prepare well‐dispersed Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles. Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles exhibited a superparamagnetic behavior (i.e., no hysteresis loop) and high‐saturated magnetization (Ms = 21.5 emu/g). The structure of the composite was characterized by Fourier‐transform infrared spectra, X‐ray powder diffraction patterns, and transmission electron microscopy, which proved that the Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles were about 20 nm. Moreover, the thermal properties of the composite were evaluated by thermogravimetric analysis, and it showed excellent thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1666–1671, 2006 相似文献
759.
William F. Alves Darcy H. F. Kanda Luiz F. Malmonge José A. Malmonge Luiz H. C. Mattoso 《应用聚合物科学杂志》2007,105(2):706-709
Blends made up of castor oil‐based polyurethane (PU) and poly(o‐methoxyaniline) (POMA) were obtained in the form of films by casting and characterized by FTIR, UV‐Vis‐NIR spectroscopy, and electrical conductivity measurements. Doping was carried out by immersing the films in 1.0M HCl aqueous solution. Chemical bonds between NCO group of PU and NH group of POMA were observed by means of FTIR spectra. The UV‐Vis‐NIR spectra indicated that the presence of the PU in the blend does not affect doping and formation of the POMA phase. The electrical conductivity research was in the range of 10?3 S/cm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
760.
The kinetic,morphological,crystallographic,and magnetic characteristics of thermally induced martensites in Fe-13.4wt%Mn-5.2wt% Mo alloy were investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),and M(o)ssbauer spectroscopy.The experimental results reveal that two types of thermal-induced martensites,ε(hcp)and αˊ(bcc)martensites,are formed in the as-quenched condition,and these transformations have athermal characters.Mo addition to the Fe-Mn alloy does not change the coexistence of ε and αˊ martensites with the Mn content between 10wt% and 15wt%.Besides,M(o)ssbauer spectra reveal a paramagnetic character with a singlet for the γ(fcc)austenite and ε martensite phases and a ferromagnetic character with a broad sextet for the αˊ martensite phase.The volume fraction of αˊmartensite forming in the quenched alloy is much more than that of the ε martensite. 相似文献