八面河地区地层剥蚀线研究

地层剥蚀线在地震剖面上由于处在地层超覆或剥蚀削蚀点附近,受地震资料分辨率的限制,地震反射往往提前变弱或消失,依据地震资料追踪的地层超覆和剥蚀削蚀线与实际地层超覆和剥蚀削蚀线存在较大的差异,因而不能根据砂组顶面反射同相轴的特征来准确判断砂组超覆和剥蚀削蚀线的位置。如何准确确定地层剥蚀削蚀线的位置,对于正确认识地层油藏分布和规模,指导油气勘探开发具有重要意义。瞬时相位及地层剥蚀线综合外推法能有效地解决剥蚀削蚀线外推问题。

八面河南部斜坡带地层剥蚀线探讨

地层剥蚀线在地震剖面上由于处在地层超覆或剥蚀削蚀点附近，受地震资料分辨率的限制，地震反射往往提前变弱或消失，依据地震资料追踪的地层超覆和剥蚀削蚀线与实际地层超覆和剥蚀削蚀线存在较大的差异，因而不能根据砂组顶面反射同相轴的特征来准确判断砂组超覆和剥蚀削蚀线的位置。如何准确确定地层剥蚀削蚀线的位置，对于正确认识地层油藏分布和规模，指导油气勘探开发具有重要意义。瞬时相位及地层剥蚀线综合外推法能有效地解决剥蚀削蚀线外推问题。

沿海地带大气热稳定性判定模型及其在风切变的应用研究

文章基于某沿海测风塔的实测风数据,分析比较了不同大气热稳定度判定参数及分类标准对沿海地带风切变系数计算的适用性,并采用合适的大气热稳定度分类方法对该地区的大气热稳定度进行分类,计算不同大气热稳定度等级下的风切变系数,外推高层风速,并与该测风塔的实测高层风速进行对比分析。分析结果表明:推算小风速时误差较大;风切变系数的日变化与大气热稳定性的日变化存在着高度的相关性;相比于其他判定模型,使用基于梯度理查森数的模型能得到更具有鲁棒性的风廓线特性;相比于传统的不分类推算方法,按照不同热稳定性下的风切变系数外推可得到更准确的高层风速。

SnO_2-based solid solutions for CH_4 deep oxidation: Quantifying the lattice capacity of SnO_2 using an X-ray diffraction extrapolation method

A series of SnO2‐based catalysts modified by Mn, Zr, Ti and Pb oxides with a Sn/M （M=Mn, Zr, Ti and Pb） molar ratio of 9/1 were prepared by a co‐precipitation method and used for CH4 and CO oxidation. The Mn3＋, Zr4＋, Ti4＋and Pb4＋cations are incorporated into the lattice of tetragonal rutile SnO2 to form a solid solution structure. As a consequence, the surface area and thermal stability of the catalysts are improved. Moreover, the oxygen species of the modified catalysts become easier to be reduced. Therefore, the oxidation activity over the catalysts was improved, except for the one modified by Pb oxide. Manganese oxide demonstrates the best promotional effects for SnO2. Using an X‐ray diffraction extrapolation method, the lattice capacity of SnO2 for Mn2O3 was 0.135 g Mn2O3/g SnO2, which indicates that to form stable solid solution, only 21%Sn4＋cations in the lattice can be maximally replaced by Mn3＋. If the amount of Mn3＋cations is over the capacity, Mn2O3 will be formed, which is not favorable for the activity of the catalysts. The Sn rich samples with only Sn‐Mn solid solution phase show higher activity than the ones with excess Mn2O3 species.

Analysis of structural hot-spot stress in orthotropic plates

On the basis of the actual steel deck structure of Taizhou Bridge, this paper carries out hot-spot stress analysis on some key spots by using the finite element model which simulates local structure of orthotropic steel bridge decks. A finite element model is established for local structure of orthotropic steel bridge decks, and in the analysis of linear elasticity of the structure, face load is employed to simulate the loads from vehicle wheels. Analysis results show that main stresses are relatively heavy at the joints between diaphragm plates, top plates and U-shaped ribs and the joints between diaphragm plates and U-shaped ribs. These joints shall be regarded as key points for hot-spot stress analysis. Different mesh densities are adopted in the finite element model and the main stresses at different hot spots are contrasted and linear extrapolation is carried out using extrapolation formulae. Results show that different mesh densities have different influences on the hot-spot stresses at the welded seams of U-shaped ribs. These influences shall be considered in calculation and analysis.

Asymptotic expansions of finite element solutions to Robin problems in H^3 and their application in extrapolation cascadic multigrid method

For the Poisson equation with Robin boundary conditions,by using a few techniques such as orthogonal expansion(M-type),separation of the main part and the finite element projection,we prove for the first time that the asymptotic error expansions of bilinear finite element have the accuracy of O(h3)for u∈H3.Based on the obtained asymptotic error expansions for linear finite elements,extrapolation cascadic multigrid method(EXCMG)can be used to solve Robin problems effectively.Furthermore,by virtue of Richardson not only the accuracy of the approximation is improved,but also a posteriori error estimation is obtained.Finally,some numerical experiments that confirm the theoretical analysis are presented.

Stability of proteins with multi-state unfolding behavior

A new model used to calculate the free energy change of protein unfolding is presented. In this model, proteins are considered to be composed of structural elements. The unfolding of a structural element obeys a two-state mechanism and the free energy change of the element can be obtained by a linear extrapolation method. If a protein consists of the same structural elements, its unfolding will displays a two-state process, and only the average structural element free energy change 〈△G0 element（H2O）〉 can be measured. If protein consists of completely different structural elements, its unfolding will show a multi-state behavior. When a protein consists of n structural elements its unfolding will shows a （n＋1）-state behavior. A least-squares fitting can be used to analyze the contribution of each structural element to the protein and the free energy change of each structural element can be obtained by using linear extrapolation to zero denaturant concentration, not to the start of each transition. The measured △Gn protein（H2O） is the sum of the free energy change for each structural element. Using this new model, we can not only analyze the stability of various proteins with similar structure and similar molecular weight, which undergo multi-state unfolding processes, but also compare the stability of proteins with different structures and molecular weights using the average structural element free energy change 〈△G0 element（H2O）〉. Although this method cannot completely provide the exact free energy of proteins, it is better than current methods.

Extrapolation cascadic multigrid method on piecewise uniform grid

The triangular linear finite elements on piecewise uniform grid for an elliptic problem in convex polygonal domain are discussed. Global superconvergence in discrete Hi-norm and global extrapolation in discrete L2-norm are proved. Based on these global estimates the conjugate gradient method （CG） is effective, which is applied to extrapolation cascadic multigrid method （EXCMG）. The numerical experiments show that EXCMG is of the global higher accuracy for both function and gradient.