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排序方式: 共有461条查询结果,搜索用时 15 毫秒
1.
本文简要介绍了埕岛油田海管工程结构设计及海管的特点,结合埕岛油田实际,讨论了海管的埋深、稳定、结构型式等。 相似文献
3.
在较弱的条件下,借助Ekdland变分原理,研究了下面的微分包含解的存在性:X'(t)∈F(t,x(t)),t∈[0,T],x(0)=x0 相似文献
4.
本文介绍了古洞面板混凝土W型止水铜片连续制作 以及安装的施工方法,通过采该项工艺,面板混凝土施工工期得到了保证。 相似文献
5.
YIN Hong TAO Kun PAN Jinsheng LI Hengde Tsinghua University Beijing China professor.Department of Materials Science Engineering Tsinghua University Beijing China 《金属学报(英文版)》1993,6(3):145-152
The critical _d vahues ( _ ) of the γ/(γ+σ).γ/(γ+μ) and γ/(γ+γ') phase boundaries insome ternar alloy phase diagrams at various temperatures are calculated by averaging the _d values of sererai selected characteristic points at the phase boundaries.Approxmateequations for the temperature dependence of the critical _d of γ/(γ+σ).γ/(γ+μ) andγ/(γ+γ') phase boundaries are established.The accuracy of the analysis is discussed in detail.It is found for the first time that the average value of the bondorder _ at the phase boundaries ts also approximatelr a constant and therefore a criticalaverage bond order _ like - can be introduced for the analysts of phase stability 相似文献
6.
Jiangyong Yuan Yannan Zhao Haiwen Xu Chunqiang Lu Kun Yang Xing Zhu Kongzhai Li 《中国化学工程学报》1982,28(10):2668-2676
A series of layered Mg-Al spinel supported Ce-Fe-Zr-O oxygen carriers were prepared for co-production of syngas and pure hydrogen via chemical looping steam reforming (CLSR). The presence of magnesium-aluminum layered double oxides (MgAl-LDO) significantly increases the specific surface area of the mixed oxides, reduces the particle size of CeO2-based solid solution and promotes the dispersion of free Fe2O3. When reacting with methane, MgAl-LDO supported oxygen carrier shows much lower temperature for methane oxidation than the pure CeFe-Zr-O sample, indicating enhanced low-temperature reactivity. Among different Ce-Fe-Zr-O(x)/MgAl-LDO samples, the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO sample shows the best performance for the selective oxidation of methane to syngas and the H2 production by water splitting. After a long period of high temperature redox experiment, the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO oxygen carrier still shows high activity for syngas generation. The comparison on the morphology of the fresh and cycled oxygen carriers indicates that the Mg-Al spinel support still forms a stable skeleton structure with high dispersion of active components on the surface after the long-term cycling, which contributes to excellent redox stability of the Ce-Fe-Zr-O(40 wt%)/MgAl-LDO oxygen carrier. 相似文献
7.
XU Bin WU ZhenSen WU Jian & XUE Kun School of Science Xidian University Xi’an China State Key Laboratory of Electromagnetic Environment China Research Institute of Radiowave Propagation Beijing 《中国科学E辑(英文版)》2009,52(4):1112-1116
The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere
region are presented with consideration of the elastic collision between electrons and neural particles and the excitation
of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase
of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian
feature is weakened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be considered
in the inversion.
Supported by the National Natural Science Foundation of China (Grant No. 40310223), the National Key Laboratory of Electromagnetic
Environment (LEME), and National Key Technologies R&D Program of China (Grant No. 2006BAB18B06) 相似文献
8.
According to the characteristics of fluid-structure interaction(FSI) in the process of metal bellows inflating to disperse bomblets,a 3D dynamical FSI model(W model) which describes the interaction between a viscous compressible flow and a structure undergoing large deformationis established.Then the dynamic characteristics of the metal bellows deformation, the changing law of the internal flow field and the motion law of the bombs are acquired.Where the internal pressure and bombs'' moving law are approximate to interior ballistic results, which indicates the W model established reasonably.Besides, considering gaps existing atthe bellows'' tow ends, the dynamical FSI modelcontaining gaps(Y model) is also built.The results of the W and Y models are compared and the results show that the existence of the gaps has little influence to the flow field and the stress distributionin the bellows,but obviously reduces the separation speed of the bomblets about 10%. 相似文献
9.
The mechanism of the multiple-pathway and multiple-step degradation reactions of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins with H and Cl atoms is investigated using the density functional theory.The electronic structures and the minimum energy path(MEP)are calculated at the B3LYP/6-311+G(d,p)level,and energetic information(single-point)is further refined at the B3LYP/6-311++G(3df,2p)level.The main possible ring opening reaction pathways of the C–O bond breakdown include indirect cleavage ring opening reaction,hydrogen addition reaction,hydrogen addition elimination reaction,and chlorine addition elimination reaction.Ten reaction steps of the six reaction pathways are considered.Our calculations indicate that hydrogen addition reaction step TS1c is of the smallest barrier height,and indirect cleavage ring opening reaction channel has the largest barrier height and is the most endothermic. 相似文献
10.
Liu Ning 《中国有色金属学会会刊》1996,(3)
EFFECTOFRAREEARTHELEMENTErONSTRENGTHENINGOFINTERFACEOFTi(C,N)BASEDCERMETS¥LiuNing(DepartmentofMaterialsScienceandEngineering,... 相似文献