The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
S Wagner - One of the best experts on this subject based on the ideXlab platform.
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electrical response of amorphous silicon thin film transistors under mechanical strain
Journal of Applied Physics, 2002Co-Authors: Helena Gleskova, S Wagner, W O Soboyejo, Zhigang SuoAbstract:We evaluated amorphous silicon thin-film transistors (TFTs) fabricated on polyimide Foil under uniaxial compressive or tensile strain. The strain was induced by bending or stretching. The on- current and hence the electron linear mobility μ depend on strain e as μ=μ0(1+26×e), where tensile strain has a positive sign and the strain is parallel to the TFT source-drain current path. Upon the application of compressive or tensile strain the mobility changes “instantly” and under compression then remains constant for up to 40 h. In tension, the TFTs fail mechanically at a strain of about +0.003 but recover if the strain is released “immediately.”
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failure resistance of amorphous silicon transistors under extreme in plane strain
Applied Physics Letters, 1999Co-Authors: Helena Gleskova, S WagnerAbstract:We have applied strain on thin-film transistors (TFTs) made of hydrogenated amorphous silicon on polyimide Foil. In tension, the amorphous layers of the TFT fail by periodic cracks at a strain of ∼0.5%. In compression, the TFTs do not fail when strained by up to 2%, which is the highest value we can set controllably. The amorphous transistor materials can support such large strains because they lack a mechanism for dislocation motion. While the tensile driving force is sufficient to overcome the resistance to crack formation, the compressive failure mechanism of delamination is not activated because of the large delamination length required between transistor layers and polymer substrate.
Helena Gleskova - One of the best experts on this subject based on the ideXlab platform.
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electrical response of amorphous silicon thin film transistors under mechanical strain
Journal of Applied Physics, 2002Co-Authors: Helena Gleskova, S Wagner, W O Soboyejo, Zhigang SuoAbstract:We evaluated amorphous silicon thin-film transistors (TFTs) fabricated on polyimide Foil under uniaxial compressive or tensile strain. The strain was induced by bending or stretching. The on- current and hence the electron linear mobility μ depend on strain e as μ=μ0(1+26×e), where tensile strain has a positive sign and the strain is parallel to the TFT source-drain current path. Upon the application of compressive or tensile strain the mobility changes “instantly” and under compression then remains constant for up to 40 h. In tension, the TFTs fail mechanically at a strain of about +0.003 but recover if the strain is released “immediately.”
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failure resistance of amorphous silicon transistors under extreme in plane strain
Applied Physics Letters, 1999Co-Authors: Helena Gleskova, S WagnerAbstract:We have applied strain on thin-film transistors (TFTs) made of hydrogenated amorphous silicon on polyimide Foil. In tension, the amorphous layers of the TFT fail by periodic cracks at a strain of ∼0.5%. In compression, the TFTs do not fail when strained by up to 2%, which is the highest value we can set controllably. The amorphous transistor materials can support such large strains because they lack a mechanism for dislocation motion. While the tensile driving force is sufficient to overcome the resistance to crack formation, the compressive failure mechanism of delamination is not activated because of the large delamination length required between transistor layers and polymer substrate.
Zhigang Suo - One of the best experts on this subject based on the ideXlab platform.
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electrical response of amorphous silicon thin film transistors under mechanical strain
Journal of Applied Physics, 2002Co-Authors: Helena Gleskova, S Wagner, W O Soboyejo, Zhigang SuoAbstract:We evaluated amorphous silicon thin-film transistors (TFTs) fabricated on polyimide Foil under uniaxial compressive or tensile strain. The strain was induced by bending or stretching. The on- current and hence the electron linear mobility μ depend on strain e as μ=μ0(1+26×e), where tensile strain has a positive sign and the strain is parallel to the TFT source-drain current path. Upon the application of compressive or tensile strain the mobility changes “instantly” and under compression then remains constant for up to 40 h. In tension, the TFTs fail mechanically at a strain of about +0.003 but recover if the strain is released “immediately.”
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ductile failure of a constrained metal Foil
Journal of The Mechanics and Physics of Solids, 1991Co-Authors: A G Varias, Zhigang Suo, C F ShihAbstract:Abstract A metal Foil bonded between stiff ceramic blocks may fail in a variety of ways, including de-adhesion of interfaces, cracking in the ceramics and ductile rupture of the metal. If the interface bond is strong enough to allow the Foil to undergo substantial plastic deformation dimples are usually present on fracture surfaces and the nominal fracture energy is enhanced. Ductile fracture mechanisms responsible for such morphology include (i) growth of near-tip voids nucleated at second-phase particles and or interface pores, (ii) cavitation and (iii) interfacial debonding at the site of maximum stress which develops at distances of several Foil thicknesses ahead of the crack tip. For a crack in a low to moderately hardening bulk metal, it is known that the maximum mean stress which develops at a distance of several crack openings ahead of the tip does not exceed about three times the yield stress. In contrast, the maximum mean stress that develops at several Foil thicknesses ahead of the crack tip in a constrained metal Foil can increase continuously with the applied load. Mean stress and interfacial traction of about four to six times the yield of the metal Foil can trigger cavitation and/or interfacial debonding. The mechanical fields which bear on the competition between failure mechanisms are obtained by a large deformation finite element analysis. Effort is made to formulate predictive criteria indicating, for a given material system, which one of the several mechanisms operates and the relevant parameters that govern the nominal fracture work. The shielding of the crack tip in the context of ductile adhesive joints, due to the non-proportional deformation in a region of the order of the Foil thickness, is also discussed.
Issarachai Ngamroo - One of the best experts on this subject based on the ideXlab platform.
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An optimization of robust SMES with specified structure H∞ controller for power system stabilization considering superconducting magnetic coil size
Energy Conversion and Management, 2010Co-Authors: Issarachai NgamrooAbstract:Even the superconducting magnetic energy storage (SMES) is the smart stabilizing device in electric power systems, the installation cost of SMES is very high. Especially, the superconducting magnetic coil size which is the critical part of SMES, must be well designed. On the contrary, various system operating conditions result in system uncertainties. The power controller of SMES designed without taking such uncertainties into account, may fail to stabilize the system. By considering both coil size and system uncertainties, this paper copes with the optimization of robust SMES controller. No need of exact mathematic equations, the normalized coprime factorization is applied to model system uncertainties. Based on the normalized integral square error index of inter-area rotor angle difference and specified structured H∞ loop shaping optimization, the robust SMES controller with the smallest coil size, can be achieved by the genetic algorithm. The robustness of the proposed SMES with the smallest coil size can be confirmed by simulation study.
Xiao Wen-zhong - One of the best experts on this subject based on the ideXlab platform.
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Development of Peelable Ultra-thin Copper Foil with Carrier Foil
Nonferrous Metals Science and Engineering, 2010Co-Authors: Xiao Wen-zhongAbstract:The production of ultra-thin copper Foil mainly uses carrier Foil with a certain thickness as the cathode, with electro-deposition of copper on it. The key technology of the ultra-thin copper Foil production is the peeling of the ultra-thin copper Foil from the carrier. This paper summarizes the current researches on the peeling layer between the ultra-thin copper Foil and the carrier. The prospect for the ultra-thin copper Foil production is also predicted.
