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618 results on '"Somer M"'

160. Contact mechanics for soft robotic fingers: modeling and experimentation.

Author

Bakhy, Sadeq H., Hassan, Shaker S., Nacy, Somer M., Dermitzakis, K., and Arieta, Alejandro Hernandez

Subjects
ROBOTICS, CONTACT mechanics, HUMANOID robots, BIOMIMETIC chemicals, ELASTIC deformation, POWER law (Mathematics)
Abstract

Human fingers possess mechanical characteristics, which enable them to manipulate objects. In robotics, the study of soft fingertip materials for manipulation has been going on for a while; however, almost all previous researches have been carried on hemispherical shapes whereas this study concentrates on the use of hemicylindrical shapes. These shapes were found to be more resistant to elastic deformations for the same materials. The purpose of this work is to generate a modified nonlinear contact-mechanics theory for modeling soft fingertips, which is proposed as a power-law equation. The contact area of a hemicylindrical soft fingertip is proportional to the normal force raised to the power of γcy, which ranges from 0 to 1/2. Subsuming the Timoshenko and Goodier (S. P. Timoshenko and J. N. Goodier, Theory of Elasticity, 3rd ed. (McGraw-Hill, New York, 1970) pp. 414–420) linear contact theory for cylinders confirms the proposed power equation. We applied a weighted least-squares curve fitting to analyze the experimental data for different types of silicone (RTV 23, RTV 1701, and RTV 240). Our experimental results supported the proposed theoretical prediction. Results for human fingers and hemispherical soft fingers were also compared. [ABSTRACT FROM AUTHOR]

Published
2013
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171. Sol–gel synthesis and lithium ion conductivity of Li7La3Zr2O12 with garnet-related type structure

Author

Kokal, I., Somer, M., Notten, P.H.L., and Hintzen, H.T.

Subjects
*LITHIUM ions, *ELECTRIC conductivity, *GARNET, *NANOSTRUCTURED materials, *NANOCRYSTALS, *SCANNING electron microscopy
Abstract

Abstract: Lithium ion conducting garnet-related type Li7La3Zr2O12 (LLZO) nanopowders were prepared by the modified sol–gel Pechini method from the stoichiometric mixtures of lithium carbonate, lanthanum oxide and zirconium ethoxide. The LLZO precursor powders were annealed at various temperatures between 923 and 1173K for 5h in air atmosphere. The products were characterized by thermal analysis (TG/DTA) and X-ray powder diffraction (XRPD) to verify the transformation from precursor powder to crystalline garnet-related phase. XRPD analysis shows that cubic phase of garnet-related type Li7La3Zr2O12 is formed at 978K and the tetragonal garnet-related phase above 997K. The morphology of the particles was investigated by Scanning Electron Microscopy (SEM). The lithium ionic conductivity of the tetragonal Li7La3Zr2O12 sample prepared by sol–gel synthesis method is found to be 3.12×10−7 S/cm at 298K while the corresponding activation energy is 0.67eV. The results of the ionic conductivities are in good agreement with those of the tetragonal LLZO synthesized by conventional solid-state synthesis method. [Copyright &y& Elsevier]

Published
2011
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174. Fabrication of yttria stabilized zirconia nanoparticles by the reverse microemulsion method for SOFC applications.

Author

VATANSEVER, S., ÖKSÜZÖMER, F., KOÇ, S. NACI, SOMER, M., DELIGÖZ, H., and GÜRKAYNAK, M. A.

Subjects
ZIRCONIUM oxide, NANOPARTICLES, CHEMICAL reactions, ELECTRON microscopy, MICROSCOPY
Abstract

Yttria stabilized zirconia powders were synthesized by the reverse microemulsion method. Powders were calcined from 600 °C to 1000 °C and sintered at 1450 °C. Crystalline properties and microstructure of samples were characterized by X-ray diffraction and scanning electron microscopy, respectively. Oxygen ionic conductivity was measured by electrochemical impedance spectroscopy. Sizes of yttria stabilized zirconia particles calcined at 1000 °C are lower than 100 nm, and approximately, 1 µm grain was obtained after sintering at 1450 °C. [ABSTRACT FROM AUTHOR]

Published
2010

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