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SelectedWorks

2008

Articles 1 - 5 of 5

Full-Text Articles in Engineering Science and Materials

Effect Of Concentration On Electrospun Polyacrylonitrile (Pan) Nanofibers, Ji-Huan He, Yu-Qin Wan, Jian-Yong Yu Jan 2008

Effect Of Concentration On Electrospun Polyacrylonitrile (Pan) Nanofibers, Ji-Huan He, Yu-Qin Wan, Jian-Yong Yu

Ji-Huan He

Abstract: An allometrical scaling relationship between the diameter of electrospun nanofiber and solution concentration is established, the scaling exponent differs greatly between different polymers and the same polymer with different molecules or the same molecules with different properties. The diameter of electrospun polyacrylonitrile (PAN) nanofibers increases approximately linearly with solution concentration.

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Nanocomposite Powders For New Contact Materials Based On Copper And Alumina, Zeljko J. Kamberovic Jan 2008

Nanocomposite Powders For New Contact Materials Based On Copper And Alumina, Zeljko J. Kamberovic

Zeljko J Kamberovic

This paper is a contribution to characterization of Cu-Al2O3 powders with nanostructure designed for the production of dispersion strengthened contact materials. New materials with predetermined properties can be successfully synthesized by utilizing the principles of hydrometallurgy and powder metallurgy. The results show a development of a new procedure for the synthesis. The applied characterization methods were differential thermal and thermogravimetric analysis (DTA-TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM): Focused Ion Beam (FIB) and Analytical Electron Microscopy (AEM). Nanostructure characteristics, particle size in range 20-50 nm, and uniform distribution of dispersoide in copper matrix were validated.

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Determination Of Al2o3 Particle Size In Cu-Al2o3 Nanocomposite Materials Using Uv Spectrophotometry, Zeljko J. Kamberovic Jan 2008

Determination Of Al2o3 Particle Size In Cu-Al2o3 Nanocomposite Materials Using Uv Spectrophotometry, Zeljko J. Kamberovic

Zeljko J Kamberovic

In order to achieve improved mechanical properties of dispersion strengthened nanocomposite, without influencing electrical and thermal conductivity it is necessary for dispersoide to be nano sized and uniformly distributed in base metal matrix. In this paper are presented the results concerning possibility of using UV spectrophotometry for determination of alumina particle size in Cu-Al2O3 system. Presented results show that this method is unefficient as method for determination of dispersoide particle size, due to the coalescence of particles false results are obtained, i.e. particle size significantly higher then one determined by image analysis.

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Structural Characteristics Of Some Ternary Ag-In-Sn Alloys, Zeljko J. Kamberovic Jan 2008

Structural Characteristics Of Some Ternary Ag-In-Sn Alloys, Zeljko J. Kamberovic

Zeljko J Kamberovic

The Ag-In-Sn system, as one of potential lead-free solder materials, was studied in this paper. The investigated alloys were chosen from two sections, with molar ratio of In:Sn equal to 1:4; 1:2. DTA, XRD, SEM and microhardness investigations were used in order to determine structural characteristics of chosen Ag-In-Sn ternary alloys.

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An Improved Robust Projection Identification Algorithm To Manned Maneuvering Units, Bin Xu Jan 2008

An Improved Robust Projection Identification Algorithm To Manned Maneuvering Units, Bin Xu

Bin Xu

空间载人机动装置(MMU )在进行救援过程中, 其动力学参数存在很大的不确定性。为解决这一辨识问题, 本文首先推导系统关于各动力学参数的线性化模型, 然后结合该线性模型的特点, 提出了一种用于估计动力学参数的改进鲁棒投影算法, 并在理论上分析了该算法的收敛性质, 数字仿真验证了方法的有效性。

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