5,717 research outputs found
A densification model for powder materials under cold isostatic pressing-Effect of adhesion and friction of rubber molds
No full textThe effect of adhesion and friction of a rubber mold oil powder compacts was studied during unloading under cold isostatic pressing. The densification model by Lee and Kim was used for compaction of powder, based on the yield function of the Cap model and volumetric strain evolution. The bilinear cohesive model was used to Study a detaching process and stress distributions at the interface between the mold and the compact. We also studied the failure of the powder compact during unloading under cold isostatic pressing due to friction at the interface, and compared experimental data with finite element results. (c) 2008 Elsevier B.V. All rights reserved.X119sciescopu
Densification behavior of nanocrystalline titania powder under cold compaction
No full textDensification behavior of nanocrystalline titania powder was investigated under cold compaction. Experimental data were obtained from triaxial compression with various loading conditions. Lee and Kim proposed the Cap model by employing the parameters involved in the yield function of sintered metal powder and volumetric strain evolution under cold isostatic pressing. The parameters in the Drucker/Prager Cap model and the proposed Cap model were obtained from experimental data under triaxial compression. Finite element results from the models were compared with experimental data for densification behavior of nanocrystalline ceramic powder under cold isostatic pressing and die compaction. The proposed model and the Drucker/Prager Cap model agreed well with experimental data under cold compaction. Finite element results and experimental data also, show that relative density distribution of nanocrystalline ceramic powder compacts is nonuniform compared to the conventional micron powder compacts at the same averaged relative density. (c) 2007 Elsevier B.V. All rights reserved.X119sciescopu
Electrochemical characterizations on MnO2 supercapacitors with potassium polyacrylate and potassium polyacrylate-co-polyacrylamide gel polymer electrolytes
No full textThe Fabrication Process, Microstructures, and Mechanical Properties of Alumina Fabricated from Amorphous Powders by Spark Plasma Sintering(SPS) Process
No full textDraft genome sequence of Mycobacterium tuberculosis KT-0192, isolated in South Korea
No full textWe report the draft genome sequence of totally drug-resistant (XDR) Mycobacterium tuberculosis KT-0192. This sequence will provide new insights into the main cause and evolution of drug resistance in M. tuberculosis KT-0192. © 2016 Lee et al.N
Supplementary Material for: Association of serum activin levels with allograft outcomes in patients with kidney transplant: Results from the KNOW-KT
No full textIntroduction: Serum activin A has been reported to contribute to vascular calcification and kidney fibrosis in chronic kidney disease. We aimed to investigate whether higher serum activin levels were associated with poor allograft outcomes in patients with kidney transplants (KT).
Methods: A total of 860 KT patients from KNOW-KT (KoreaN cohort study for Outcome in patients With Kidney Transplantation) were analyzed. We measured serum activin levels at pre-KT and 1 year after KT. The primary outcome was the composite of a ≥ 50% decline in eGFR and graft failure. Multivariable cause-specific hazard model was used to analyze association of 1-year activin levels with the primary outcome. The secondary outcome was coronary artery calcification score (CACS) at 5 years after KT.
Results: During the median follow-up of 6.7 years, the primary outcome occurred in 109 (12.7%) patients. The serum activin levels at 1 year were significantly lower than those at pre-KT (488.2 ± 247.3 vs. 704.0 ± 349.6). When patients were grouped based on the median activin level at 1 year, the high-activin group had a 1.91-fold higher risk (95% CI, 1.25-2.91) for the primary outcome compared to the low-activin group. A one standard deviation increase in activin levels as a continuous variable was associated with a 1.36-fold higher risk (95% CI, 1.16-1.60) for the primary outcome. Moreover, high activin levels were significantly associated with 1.56-fold higher CACS (95% CI, 1.12-2.18).
Conclusion: Post-transplant activin levels were independently associated with allograft functions as well as coronary artery calcification in kidney transplant patients
Rubber isostatic pressing of metal powder under warm temperatures
No full textThe effect of a rubber mould on densification and deformation of aluminum alloy powder was investigated during warm isostatic pressing. The hyperelastic constitutive equations based on various strain energy potentials were employed to analyze deformation of a rubber mould. The parameters in the strain energy potentials were obtained from experimental data for uniaxial and volumetric responses of Viton rubber at elevated temperatures. The yield function of Shima and Oyane was implemented into a finite element program (ABAQUS) to predict compaction responses of metal powder during warm isostatic pressing. Finite element results were compared with experimental data for densification and deformation of aluminum alloy powder during warm die pressing and warm isostatic pressing. (C) 2004 Elsevier B.V. All rights reserved.X116sciescopu
The effect of a rubber mold on densification and deformation of a metal powder compact during cold isostatic pressing
No full textThe effect of a rubber mold on densification behavior and deformation of an iron powder compact was investigated under cold isostatic pressing. The hyperelastic constitutive equations based on various strain energy potentials were employed to analyze deformation of rubber. The parameters in the strain energy potentials were obtained from experimental data for uniaxial tension, compression, and volumetric compression of natural rubber. The elastoplastic constitutive equation based on the yield function of Shima and Oyane was implemented into a finite element program (ABAQUS) to predict compaction responses of metal powder under cold isostatic pressing. Finite element results were compared with experimental data for densification and deformation of an iron powder compact under cold isostatic pressing. (C) 2001 Elsevier Science B.V. All rights reserved.X1111sciescopu
Formulation and validation of boundary conditions at a branched junction for nonlinear waves
No full textA numerical model is presented for the calculation of nonlinear waves through the branched junctions in a gas transmission pipe system. In the one-dimensional time domain analysis of the wave dynamics. the behaviour of the nonlinear waves is determined by quasi-steady boundary conditions at junctions in a pipe system. The quasi-steady treatment through the junction yields a system of nonlinear balance equations. The iterative solution procedure of the system of nonlinear equations causes the problems of divergence and multiple solutions. In order to overcome the difficulties, a new set of quasi-linear balance equations is formulated without a sacrifice of accuracy. The present model, therefore, requires a non-iterative solution procedure that results in a unique solution and a smaller computational effort. Thompson's boundary condition is used at each pipe. A new time-derivative form of balance equations, based Thompson' boundary condition, gives a set of linear algebraic equations for the balance equations. When implementing the new time-derivative form of the balance equations, corrected terms are added numerically. The present numerical model is implemented and tested for the calculation of behaviour of nonlinear waves in a branched pipe and the calculation of sound attenuation of a Helmholtz resonator and the prediction of radiated orifice noise of an internal combustion engine. Calculation results show good agreements with previous iterative calculations and measurement data. (c) 2006 Published by Elsevier Ltd
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