不同锌钛比对纳米钛酸锌（ZnO—TiO2）体系成分的影响

以工业偏钛酸、硫酸锌、氨水为主要原料，用直接沉淀法并进行热处理得到钛酸锌粉体，并用XRD对产物成分进行了检测。结果表明，不同的锌钛比对钛酸锌（ZnO-TiO2）体系的成分有较大影响。     

A Modified Variational-Gradient Method for Quasilinear Equations

A modified variational-gradient method is proposed and substantiated for quasilinear operator equations in a Hilbert space.     

Stabilization Methods for Spectral Element Computations of Incompressible Flows

A stabilization method for the spectral element computation of incompressible flow problems is investigated. It is based on a filtering procedure which consists in filtering the velocity field by a spectral vanishing Helmholtz-type operator at each time step. Relationship between this filtering procedure and SVV-stabilization method, introduced recently in [JCP, 2004, 196(2), p680], is established. A number of numerical examples are presented to show the accuracy and stabilization capability of the method.     

Fatigue Behavior and Retrofit Investigation of Distortion-Induced Web Gap Cracking

This paper studies a Kansas Department of Transportation welded plate girder bridge that developed fatigue cracks at small web gaps close to the girder top flange. Repair had been previously performed by softening the connection plate end with a slot retrofit, but cracks were recently found to have reinitiated at some of the repaired details and are again propagating. A comprehensive finite-element method study was performed to investigate the cracking behavior observed in the bridge and to recommend appropriate measures for future bridge retrofit. The analytical results show that stresses developed at the top flange web gaps could exceed yielding under the loading of an HS15 fatigue truck. The current slot repair used in the bridge was found to have introduced higher magnitude fatigue stresses in the web gap. To achieve a permanent repair of the bridge, it is recommended that a welded connection plate to flange attachment be used during future bridge retrofit. The web gap details should be able to withstand unlimited number of load cycles once this additional repair is performed.     

Characterization of strength properties of thin polycrystalline silicon films for MEMS applications

The aim of this work is to characterize the strength properties of polycrystalline silicon (polysilicon) with the use of tensile and bending test specimens. The strength of thin polysilicon films with different geometry, size and stress concentrations has been measured and correlated with the effective size of the specimen and its stress distribution. The test results are evaluated using a probabilistic strength approach based on the weakest link theory with the use of STAU software. The use of statistic methods of strength prediction of polysilicon test structures with a complex geometry and loading based on test values for standard material tests specimen has been evaluated.     

Effect of strain waveform on creep-fatigue life for Sn–8Zn–3Bi solder

This paper describes the creep‐fatigue life of Sn–8Zn–3Bi under push–pull loading. Creep‐fatigue tests were carried out using Sn–8Zn–3Bi specimens in fast–fast, fast–slow, slow–fast, slow–slow and hold–time strain waveforms. Creep‐fatigue lives in the slow–slow and hold‐time waveforms showed a small reduction from the fast–fast lives but those in the slow–fast and fast–slow waveforms showed a significant reduction from the fast–fast lives. Conventional creep‐fatigue life prediction methods were applied to the experimental data and the applicability of the methods was discussed. Creep‐fatigue characteristics of Sn–8Zn–3Bi were compared with those of Sn–3.5Ag and Sn–37Pb.     

Self-Irradiation Cascade Simulations in Plutonium Metal: Model Behavior at High Energy

The Modified Embedded Atom Method model for Pu metal is revised so that it more accurately captures the behavior of the Ziegler-Biersack-Littmark model of ion-ion interactions. Two revision are tested with somewhat different stiffnesses in the 2-1000 eV range. The revised models show higher damage levels at 20 KeV than an earlier model, suggesting that the behavior of the models above 100 eV is dominating damage production, at least in the earlier stages of the cascade. Work was performed at Los Alamos National Laboratory under the auspices of the US Department of Energy, under contract DE-AC52-06NA25396.     

An approach to efficient business intelligent system for financial prediction

A concept of business intelligent system for financial prediction is considered in this paper. It provides data needed for fast, precise and good business decision support to all levels of management. The aim of the project is the development of a new online analytical processing oriented on case-based reasoning (CBR) where a previous experience for every new problem is taken into account. Methodological aspects have been tested in practice as a part of the management information system development project of “Novi Sad Fair”. A case study of an improved application of CBR in prediction of future payments is discussed in the paper. This paper is originally presented at The International Conference on Hybrid Information Technology 2006, at the special session on “Intelligent Information Systems for Financial Engineering”, November 2006 in Cheju Island, Korea.     

Applications of the discrete element method in mechanical engineering

Compared to other fields of engineering, in mechanical engineering, the Discrete Element Method (DEM) is not yet a well known method. Nevertheless, there is a variety of simulation problems where the method has obvious advantages due to its meshless nature. For problems where several free bodies can collide and break after having been largely deformed, the DEM is the method of choice. Neighborhood search and collision detection between bodies as well as the separation of large solids into smaller particles are naturally incorporated in the method. The main DEM algorithm consists of a relatively simple loop that basically contains the three substeps contact detection, force computation and integration. However, there exists a large variety of different algorithms to choose the substeps to compose the optimal method for a given problem. In this contribution, we describe the dynamics of particle systems together with appropriate numerical integration schemes and give an overview over different types of particle interactions that can be composed to adapt the method to fit to a given simulation problem. Surface triangulations are used to model complicated, non-convex bodies in contact with particle systems. The capabilities of the method are finally demonstrated by means of application examples. Commemorative Contribution.     

油气集输系统新增产能建设拓扑优化方法研究

在油气集输新增产能建设中,为充分利用已建管网系统的处理能力,达到降低投资,提高经济效益的目的,进行了油气集输新增产能建设布局优化方法的研究。针对新建集输管网为树状结构的情况,建立了油气集输系统新增产能建设拓扑优化的数学模型,讨论了计算复杂性问题。根据模型的特点,将问题分解为拓扑级优化和几何级优化两个子问题,并通过它们之间的迭代进行求解。实例计算表明,所建立的数学模型正确,求解方法可行,能用于工程实际设计。