信息网格中具有动态变更适应性的元数据发布策略

信息源元数据的动态变更可能造成应用对信息源引用关系不一致，在不改应用程序的条件下，用户不能正确访问信息源。基于网格地址空间模型，使得应用程序通过虚拟层元数据，即应用领域元数据，来间接使用信息源元数据；当信息源元数据变更时，不是改应用程序而是通过调整信息源元数据和应用领域元数据之间的映射来保证应用对信息源引用关系的一致性，从元数据发布的角度出发，提出了一个具有动态适应性的元数据发布算法(Vega adaptive mapping)，通过此算法自动调整信息源元数据和应用领域元数据之间的映射；并将此算法相应的方法和现有的元数据发布方法进行了比较，比较结果表明此方法在适应元数据变更性方面具有一定的优越性。     

宇宙演化的综述和因果链

科学、物理科学的本质是探索自然和宇宙,回答它是怎样的,为什么是这样,而不是那样;即追寻科学本身的原动力。本文亦旨在此处做尝试、探讨。     

吐哈盆地中侏罗统储层成岩作用及其油气勘探意义

应用岩石溥片、铸体薄片、ｘ衍射和扫描电镜等分析资料，着重探讨吐哈盆地中侏罗统储层成岩作用及其孔隙演化，研究表明：压实作用强烈是造成储层为低孔渗性的基本原因，胶结作用受渗滤－扩散机理和热驱对流机理控制，并可形成一种成岩圈闭。     

铅基板栅合金综合性能探析

在Pb-Ca-Sn-Al合金的基础上尝试添加第五种合金元素，测试其电化学性能，并在理论上讨论了其性能提高的原因。     

Migration Processes II: The Discrete Case

Following the study of migration processes in the continuous domain in Part I of this paper, we reformulate the concept of migration in the discrete domain (Z^m) and define Discrete Migration Processes (DMP). We demonstrate that this model is a natural discrete representation of the continuous model and maintains the model's features in a qualitative sense. We show that under discrete migration any discrete set shrinks to a limit in finitely many iterations. The discrete representation provides an advantageous basis for digitally implementing the MP model. Using this implementation we illustrate the discrete migration of various types of sets under various types of constraints.     

双十二烷基长链季铵盐吸附及渗透性能的研究

双季铵盐化合物是一种具有广阔应用前景的表面活性剂。以二氯乙醚为联接剂,利用脂肪叔胺合成了一种长链的双季铵盐类化合物(简称BQA),用交流阻抗、电子扫描显微镜等方法研究了BQA在Q235钢表面的吸附、缓蚀及对生物膜下硫酸盐还原菌(SRB)的杀灭机理。研究结果表明:在模拟油田水介质中BQA对碳钢具有较为显著的缓蚀作用,与传统杀菌剂相比具有更好的渗透杀菌性能。     

The effect of precipitation of Mg2Al3 and of MnAl6 on texture evolution during isothermal annealing and subsequently on formability of CC AA5182 Al alloy

Continuous cast (CC) AA5182 Al alloy with the precipitation of Mg₂Al₃ and of MnAl₆ was cold rolled to 70% reduction and then isothermally annealed in a salt bath at three temperatures (316, 343, and 371 °C) for different times. Texture evolution during recrystallization was investigated. It was found that the recrystallization textures of the material with intense Mg₂Al₃ precipitation along the grain boundaries exhibited weaker Cube, Goss and R/β fiber components than those of the material with the more uniform fine MnAl₆ precipitates. The opposite was true in the cold rolled condition, i.e. the material with MnAl₆ precipitation had weaker Cube, Goss, and R/β fiber components in the cold rolled condition than the material with intense Mg₂Al₃ precipitation. Thus, recrystallization textures of material with Mg₂Al₃ precipitation were weaker than material with MnAl₆ precipitation. This is due to the fact that large Mg₂Al₃ particles favor the nucleation of randomly oriented grains. When subjected to formability tests, the material with prior Mg₂Al₃ precipitation displayed a lower anisotropy in tensile yield strength, ultimate tensile strength, elongation, and strain hardening exponent than material with prior MnAl₆ precipitation. This is in accord with the texture results which indicated that the recrystallization textures of material with an initial Mg₂Al₃ precipitation were closer to those of a perfectly random sample than those of material with an initial MnAl₆ precipitation. On the other hand, the elongation and Olsen values were lower and the surface quality after bending tests was worse for material with Mg₂Al₃ precipitation. This is due to the non-uniform distribution of Mg₂Al₃ particles which precipitated primarily along the grain boundaries and caused an earlier formation and coalescence of the microvoids around the grain boundary precipitates. The forming limit diagrams (FLD) correlated well with the tensile, Olsen and bending results.     

ANALYSIS OF THREE-DIMENSIONAL MACHINING USING AN EXTENDED OBLIQUE MACHINING THEORY

This paper presents an extended oblique machining theory applicable to the analysis of 3-D machining. Existing theories are evaluated to identify suitable formulations which are used with necessary modifications for predicting various quantities pertaining to cutting conditions of three dimensional machining. Actual chip flow angles extracted from measured forces, to account for the nose radius effect, are used, instead of available models, to predict important quantities such as shear plane angle, effective rake angle and shear flow angle. Experiments are conducted in the realms of conventional and high speed machining using AISI 4140 steel and aluminum 7075-T6 respectively with uncoated carbide inserts, and various process conditions pertaining to the cutting mechanics are calculated. The extended oblique machining theory is experimentally validated in predicting temperatures at the tool-chip interface and shear plane for conventional machining. Simulation results from the finite element modeling are used for verifying the shear stress and shear plane temperature predicted by the extended oblique machining theory.     

Microstructure evolution during reheating of a Nb-bearing steel I. Metallographic examination

Cooled in water after the isothermal relaxation of deformed austenite for different timea, a Nb-bearing microalloyed steel always exhibits synthetic microstructures of bainitic ferrite, granular bainite and acicular ferrite. When these samples were reheated to and held at 650 or 700℃, the non-equilibrious microstructures tend to evolve into equilibrious ones. The sample relaxed for 60 s displays the highest thermostability, while the microstructure evolution is the quickest in the sample relaxed for 1000 s even though it is the softest before reheating. Softening is not a single process occurring during reheating, in which the hardness fluctuates with time. There are two peaks in the hardness-time curve of each sample having undergone relaxation, while a single peak occurs in the curve of the sample having not been relaxed. Pre-strain accelerates the evolution process. These results indicate that the thermostability of microstructures is determined by their history of formation to a considerable degree.     

Recovery of indium and lead from lead bullion

Lead and indium were recovered by electrolysis and nonequilibrium solvent extraction process from lead bullion.The effects of current density,electrolytic period and circle amnant of electrolyte on the electrochemical dissolution of lead and indium were investigated.The effects of extraction phase ratio and mixing time on solvent extraction of indium and striping phase ratio and stripping stage on the loaded organic phase stripping were also investigated.The experimental results indicate that under optimum conditions,the purity of lead deposited on cathode is 98.5% and the deposit rate of lead is 99.9%,the dissolution rate of indium is 94.28%,the extraction rate of indium is 98.69%,the stripping rate of indium is almost 100%,and the impurity elements,such as Zn,Fe and Sn can be removed.