用光梯度场控制原子制做纳米点阵研究

提出制做纳米点阵的一种新方法。用波长为 4 2 5 .5 nm的光梯度场操纵铬原子可制做出阵列密度达 2 .2 1× 10 7per/ mm2、理论半高宽度 (FWH M)可达 10 nm的纳米点阵。介绍用光梯度场操纵原子制做纳米点阵的原理 ,对原子束的准直进行分析 ,给出原子束在激光梯度场中聚焦的经典模型和量子模型并进行数值模拟。用光操纵原子制做纳米点阵使器件的阵列密度和尖端曲率得到大幅度提高 ,该器件作为发射极可以降低工作电压和提高发射电流。     

万家寨引黄工程总干线三级泵站弦式应变计预埋故障分析

观测仪器预埋在混凝土后，其事故发生的概率尽管很小，但其发生将无法使安全监测等工作顺利进行，本文分析总干线三级泵站弦式应变计施工后无法读测的原因，供以后解决类似问题参考。     

An iterative regularization method for inverse phonon radiative transport problem in nanoscale thin films

An inverse phonon radiative transport problem with an alternative form of adjoint equation is solved in this study by using conjugate gradient method (CGM) to estimate the unknown boundary temperature distributions, based on the phonon intensity measurements. The CGM in dealing with the present integro‐differential governing equations is not as straightforward as for the normal differential equations; special treatments are needed to overcome the difficulties. Results obtained in this inverse analysis will be justified based on the numerical experiments where two different unknown temperature (or phonon intensity) distributions are to be determined. Finally, it is shown that accurate boundary temperatures can always be obtained with CGM. Copyright © 2006 John Wiley & Sons, Ltd.     

Fabrication of thick, high-quality strained SiGe layer on ultra-thin silicon-on-insulator and modeling of film strain

Fabrication of a thick strained SiGe layer on bulk silicon is hampered by the lattice mismatch and difference in the thermal expansion coefficients between Si and SiGe, and a high Ge content leads to severe strain in the SiGe film. When the thickness of the SiGe film is above a critical value (90 nm for 18% Ge), drastic deterioration of the film properties as well as dislocations will result. In comparison, a silicon-on-insulator (SOI) substrate with a thin top Si layer can mitigate the problems and so a thick SiGe layer with high Ge concentration can conceivably be synthesized. In the work reported here, a 110 nm thick high-quality strained Si_0.82Ge_0.18 layer was fabricated on an ultra-thin SOI substrate with a 30 nm top silicon layer using ultra-high vacuum chemical vapor deposition (UHVCVD). The thickness of the SiGe layer is larger than the critical thickness on bulk Si. Cross-sectional transmission electron microscopy (XTEM) reveals that the SiGe layer is dislocation-free and the atoms at the SiGe/Si interface are well aligned, even though X-ray diffraction (XRD) data indicate that the SiGe film is highly strained. The strain factors determined from the XRD and Raman results agree well.     

Lebensdauervorhersage auf Basis von Finite Elemente Ergebnissen

Fatigue Life Prediction Based on Finite Element Results The ever‐increasing pressure of competition leads to continuously decreasing product development cycle times. Therefore, information about the life time and the dimensioning of machine parts is required already in the early stages of development. Frequently, a weight optimization is desired, which implies that the local stress must come as close as possible to the strength limit for wide regions of the component under concern. This leads to an increasing use of simulation methods in design as well as in testing. For a life time prediction based on stress results from finite element computations, local S/N curves are needed, which frequently have to be deduced from S/N curves obtained from laboratory specimens. In the present contribution, the transferability from specimen S/N curves to component S/N curves is pointed out exemplarily by taking into account the influences of notches, component size, and microstructure of cast aluminum. Based on such S/N curves, which are computed for each material point in the component, the life time may be calculated by taking into account the local stresses and stress gradients obtained from finite element simulations.     

离心铸造铝-铁自生梯度复合材料梯度结构研究

为获得具有较好梯度结构的梯度材料，提出并采用了一种新的离心力-多孔金属中间层法制备锰-铁自生(in suit)梯度复合材料，进行了制备过程的实验研究。主要内容包括：工艺(材料)设计、正交实验主体、数据处理及结果分析等，重点进行了工艺参数对梯度结构影响的分析。实验结果表明，在离心转速、中间层厚度、金属温度、预热温度4个工艺参数中，中间层的极差为次大值，表明中间层的存在对梯度结构的形成有较大的影响。     

廊固凹陷万庄构造薄砂岩储层预测

薄砂岩储层是隐蔽油藏勘探的重要领域之一。廊固凹陷万庄构造沙三中段发育扇三角洲砂体,且邻近生油洼槽,有利于岩性油藏的形成。但由于砂层厚度较薄,横向变化较快,造成砂体预测不准,岩性圈闭落实困难。为此,本文采用高精度地震反演、频谱成像和储层检测等一套储层综合预测技术,精确刻画了薄砂体的展布、空间形态,查清了储层发育区,发现并落实了一批有利的岩性圈闭。根据本次综合储层预测成果部署的5口井均钻遇较厚油层,进而发现和证实万庄构造是一个具有千万吨级的整装规模的储量区。     

������ˮƽ��������ѹ���ݶ�ģ��

蛇曲井是不同于常规水平井的一种新型复杂结构井，其水平段在纵向上存在较大起伏，不能用常规水平井的压降模型计算其压降。文章对蛇曲井微元段的两相分层流动进行了分析，根据连续性方程和动量方程, 建立了蛇曲井水平段两相分层流动的压力梯度模型，在定产量和定井底流压两种工作制度下，给出了蛇曲井的水平段在两相分层流时的压降计算方法。应用文章所建模型和水平井的水平段压降计算模型分别计算了某蛇曲井水平段在气水两相分层流动时的压降，结果表明蛇曲井水平段的井筒压降不能用常规水平井水平段的压降模型计算，蛇曲井水平段的井筒压降不能忽略。     

Finite element analysis of non-isothermal multiphase geomaterials with application to strain localization simulation

Finite element analysis of non-isothermal elasto-plastic multiphase geomaterials is presented. The multiphase material is modelled as a deforming porous continuum where heat, water and gas flow are taken into account. The independent variables are the solid displacements, the capillary and the gas pressure and the temperature. The modified effective stress state is limited by the Drucker-Prager yield surface for simplicity. Small strains and quasi-static loading conditions are assumed. Numerical results of strain localization in globally undrained samples of dense, medium dense and loose sands and isochoric geomaterial are presented. A biaxial compression test is simulated assuming plane strain condition during the computations. Vapour pressure below the saturation water pressure (cavitation) develops at localization in case of dense sands, as experimentally observed. A case of strain localization induced by a thermal load where evaporation takes place is also analysed. Dedicated to Professor S. Valliappan in occasion of his retirement