塔格糖制备方法研究进展

塔格糖是一种天然的低能量填充型甜味剂，并具有抑制高血糖、改善肠道菌群和不致龋齿等多种生理功效。目前主要通过生物和化学两种方法合成。     

溶胶-凝胶法制备磷钨酸-硅胶催化合成苹果酯

采用溶胶-凝胶法制备了一系列磷钨酸-硅胶催化剂(PW/SG),考察了该催化剂催化乙酰乙酸乙酯与乙二醇液相缩合制备苹果酯的反应性能。实验结果表明,PW质量分数为40%时的PW/SG催化剂表现出最佳的催化活性;40%PW/SG催化剂制备苹果酯的最佳工艺条件为:n(乙酰乙酸乙酯)∶n(乙二醇)=1∶1.2,催化剂用量占反应物质量的0.36%,带水剂环己烷用量占反应物体积的30%,反应温度383K,反应时间90min;在此条件下,乙酰乙酸乙酯的转化率可达95.5%,苹果酯的选择性大于97%;催化剂稳定性实验表明,经5次重复使用,40%PW/SG催化剂的活性基本保持不变,乙酰乙酸乙酯转化率稳定在95.0%左右。     

SOME NEW ASPECT OF LYAPUNOV TYPE THEOREMS FOR STOCHASTIC DIFFERENCE EQUATIONS WITH CONTINUOUS TIME

Some new Lyapunov type theorems for stochastic difference equations with continuous time are proven. It is shown that these theorems simplify an application of Lyapunov functionals construction method.     

大角度倾转法在碳化物研究中的应用

蠕变过程中碳化物形貌，类型，数量和分布状态的变化直接影响着材料的高温性能，因而在材料的蠕变得到了广泛的重视，介绍了一种在碳膜萃取复型样品上利用Ｈ－８００透射电子显微镜的双倾样品台进行了大角度倾转，来观察碳化物形貌并鉴定其类型的试验方法。     

现场地质预测与决策技术

油气的生成、运移、分布、成藏、保存具有规律性，技术人员可以依据其规律性对地下地质情况进行推理、预测和决策。钻井过程的现场地质预测技术方法主要是外推法、因果法和直观法三大类。外推法是常用的预测方法，包含了岩性、沉积旋回、标志层、标准层、重矿物等岩石地层学对比方法和生物地层学方法及地球物理方法。现场地质预测与决策是通过确定预测目标、收集相关资料、进行对比分析、形成地质预测结果、拟定地质决策方案、方案优选、方案实施等环节来完成。该技术是现场地质监督的核心技术，在实践中取得显著成效。     

大红山铜矿岩体结构调查分析

大量工程实践已证明岩体结构是控制岩体稳定性的重要影响因素。为此，以大红山铜矿为研究背景，在选定有代表性调查地段的基础上，引入详细观测线法对其岩体结构进行了详细调查与统计。分析结果表明：调查区域内巷道岩体节理裂隙比较密集和发育，主要发育有倾向N53E、走向N37W、倾角53°，倾向W26S、走向N36W、倾角68°；倾向E1S、走向NIE、倾角89°的三组优势结构面，其中优势结构面第二组和第三组构成不稳定块体，并且断层及软弱夹层比较发育，加剧了巷道的破碎程度，对巷道围岩的稳定性有控制作用。最后提出了在巷道施工中密切注意围岩稳定性变化，避免工程事故的发生的建议。     

Optimized Schwarz methods without overlap for highly heterogeneous media

In this paper an original variant of the Schwarz domain decomposition method is introduced for heterogeneous media. This method uses new optimized interface conditions specially designed to take into account the heterogeneity between the sub-domains on each sides of the interfaces. Numerical experiments illustrate the dependency of the proposed method with respect to several parameters, and confirm the robustness and efficiency of this method based on such optimized interface conditions. Several mesh partitions taking into account multiple cross points are considered in these experiments.     

Mortar finite element discretization for the flow in a nonhomogeneous porous medium

Darcy’s equations model the flow of a viscous incompressible fluid in a rigid porous medium. One of the parameters of the system depends on the permeability of the medium and, when this medium is not homogeneous, the variations of the parameter could be very high. To handle this phenomenon, we propose a discretization of the model that relies on the mortar finite element method. Indeed, the idea is to construct a decomposition of the domain such that the permeability is constant on each element of the partition and to use independent meshes on the different subdomains. We perform the a priori and a posteriori analysis of this discretization and present some numerical experiments which are in good coherency with the results of the analysis.     

THE ANALYSIS OF THE SEPARATED LAYERS ALGORITHM BY DOMAIN DECOMPOSITION METHOD

From the principle of of the Domain Decomposition Method (DDM), we analyse the 2nd-order linear elliptic partial differential problems and link the Separated-Layers Algorithm (SLA) with DDM. The mathematical properties of SLA and numerical example are presented to obtain satisfactory computation results. For general linear differential ones, also are the structure of SLA and its characteristics discussed.     

Coupling techniques in boundary-combined methods for solving elliptic problems with singularities

Three coupling strategies in matching the Ritz-Galerkin method and the finite element method are introduced for general elliptic equations, and useful numerical techniques are provided. Numerical experiments have been carried out for solving the typical, singular Motz problem, which shows that optimal convergence rates of numerical solutions can be achieved by using the combined methods and techniques provided in this paper.