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排序方式: 共有9586条查询结果,搜索用时 9 毫秒
1.
Amanda Alliband Daniel W. Lenz Laura E. Stevenson Travis Whitmer Rex Cash Dennis Burns Sarah Hall William T.K. Stevenson 《Progress in Organic Coatings》2008
A model has been proposed to explain the failure of the original BMS10-39 epoxy paint on upper vertical surfaces in B-52 fuel tanks. The model involves interaction of the paint with DIEGME, a fuel system ice inhibitor (FSII) in jet fuel, that is distilled from the liquid fuel. In this communication, distillation experiments used to support the model are refined to better match the mass transfer of vapor from fuel in a B-52 fuel tank at close to room temperature. The interaction of these lower temperature distillates with the paint affirms the earlier model. On the basis of these experiments it is proposed that paint failure may be controlled or eliminated by reducing the level of DIEGME in the fuel. Proposed changes in military jet fuel composition are detailed. 相似文献
2.
Recent advances in isotropic conductive adhesives for electronics packaging applications 总被引:4,自引:0,他引:4
Isotropic conductive adhesives (ICAs) have recently received a lot of focus and attention from the researchers in electronics industry as a potential substitute to lead-bearing solders. Numerous studies have shown that ICAs possess many advantages over conventional soldering such as environmental friendliness, finer pitch printing, lower temperature processing and more flexible and simpler processing. However, complete replacement of soldering by ICAs is yet not possible owing to several limitations of ICAs which are mainly related to reliability aspects like limited impact resistance, unstable contact resistance, low adhesion and conductivity etc. Continued efforts for last 15 years have resulted in development of ICAs with improved properties. This review article is aimed at providing a better understanding of ICAs, their principles, performance and significant research and development work addressing the technological utility of ICAs. 相似文献
3.
回顾了体制、制度的改革和科学技术的发展给十局带来的巨大变化,就十局当前改革任务从理顺产权关系、进一步完善内部治理结构、继续深化三项制度改革、实施科教兴局战略等四个方面提出了看法和意见。 相似文献
4.
为了改善M2高速钢共晶碳化物的分布,本文利用小凝固试样变质的方法研究了Ti,N和Mg对M2高速钢凝固组织和硬度的影响。试验结果表明,加入Ti或Ti-N后,共晶碳化物形态和分布有很大改善,而加入Ti-N后对凝固组织有轻微的细化作用,但只添加Ti不补碳时,钢的淬火硬度和回火硬度均下降;加入适量的Mg可以使片状的M2C型共晶碳化物转为鱼骨状的M6C型共晶碳化物,使其分布有所改善,Ti和Mg复合加入可以明 相似文献
5.
Most of the UK nuclear power reactors are gas-cooled and graphite moderated. As well as acting as a moderator the graphite also acts as a structural component providing channels for the coolant gas and control rods. For this reason the structural integrity assessments of nuclear graphite components is an essential element of reactor design. In order to perform graphite component stress analysis, the definition of the constitutive equation relating stress and strain for irradiated graphite is required. Apart from the usual elastic and thermal strains, irradiated graphite components are subject to additional strains due to fast neutron irradiation and radiolytic oxidation. In this paper a material model for nuclear graphite is presented along with an example of a stress analysis of a nuclear graphite moderator brick subject to both fast neutron irradiation and radiolytic oxidation. 相似文献
6.
The effect of coherency loss on the development of precipitate size distribution under cascade-producing irradiation is considered. The nucleation of coherent precipitates, their growth followed by coherency loss and cascade-induced dissolution of large incoherent precipitates can occur simultaneously resulting in formation of a quasi-stationary size distribution of semicoherent precipitates. To describe this process we consider co-evolution of a mixed population of coherent, semicoherent and incoherent precipitates. Mathematically, the problem is formulated as a set of discrete rate equations of nucleation kinetics (the Master equation approach) which is also used for later stages of evolution. To solve the corresponding large set of equations (typically, more than 105 equations) an efficient numerical method is developed. The simulation results obtained for material parameters and irradiation conditions typical for nuclear reactors show that the coherency loss affects considerably evolution of the precipitate population. Under certain irradiation conditions, both in solution-annealed alloys and in aged ones, the mean precipitate size and the number density during prolonged irradiation tend to steady state values, whereas the size distribution function of large precipitates narrows. The width of the quasi-stationary size distribution is controlled by cascade parameters. It was found that the asymptotic quasi-stationary state of the precipitate population may depend on initial state of the alloy. 相似文献
7.
J.-P. Croisille 《Computing》2006,78(4):329-353
We introduce a new box-scheme, called ``hermitian box-scheme' on the model of the one-dimensional Poisson problem. The scheme
combines features of the box-scheme of Keller, [20], [13], with the hermitian approximation of the gradient on a compact stencil,
which is characteristic of compact schemes, [9], [21]. The resulting scheme is proved to be 4th order accurate for the primitive
unknown u and its gradient p. The proved convergence rate is 1.5 for (u,p) in the discrete L
2 norm. The connection with a non standard mixed finite element method is given. Finally, numerical results are displayed on
pertinent 1-D elliptic problems with high contrasts in the ellipticity, showing in practice convergence rates ranging from
1 to 2.5 in the discrete H
1 norm.
This work has been performed with the support of the GDR MOMAS, (ANDRA, CEA, EDF, BRGM and CNRS): Modélisation pour le stockage des déchets radioactifs. The author thanks especially A. Bourgeat for his encouragements and his interest in this work. 相似文献
8.
9.
The residual intergranular strains in textured Zircaloy-2 plate samples induced by cooling from 823 K to ambient temperatures, by cold-rolling by 1.5% and 25% and by deforming in tension by 1.5% were measured by neutron diffraction. The strong rolling texture, which gives rise to two ideal orientations, permitted the interpretation of much of the data in terms of strain tensors for the two orientations. The experimental results were compared with calculations based on the elasto-plastic self-consistent model with no adjustable parameters. Close agreement was obtained for samples in the as-cooled state and deformation in tension by 1.5% but the agreement is less satisfactory for cold-rolling. 相似文献
10.
D. Helary O. Dugne X. Bourrat P.H. Jouneau F. Cellier 《Journal of Nuclear Materials》2006,350(3):332-335
Electron back-scattering diffraction (EBSD) can be successfully performed on SiC coatings for HTR fuel particles. EBSD grain maps obtained from thick and thin unirradiated samples are presented, along with pole figures showing textures and a chart showing the distribution of grain aspect ratios. This information is of great interest, and contributes to improving the process parameters and ensuring the reproducibility of coatings. 相似文献