Papers by Keyword: Bistability

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Abstract: This article presents a non-linear model of deep groove ball bearing and results of simulation. Vibrations of this bearing are studied for a wide range of clearance. An evolution from periodic to chaotic vibrations is visible due to increase of clearance. A number of phenomena associated with non-linear dynamics are observed, for instance: bistability, chaotic vibrations, windows of periodical vibrations, jump of amplitude, period-doubling cascade leading to chaos, bifurcation directly leading to chaos, and self-similarity of a Poincaré section. Moreover, amplitudes of vibrations are presented as functions of clearance. This provides an opportunity to select failure modes. Unfortunately, relations clearance amplitude and amplitude - clearance are ambiguous.

Abstract: DLTS measurements show bistable behavior of the previously reported EH5 peak in low- and high-energy electron irradiation 4H-SiC. Both reconfiguration processes (A ! B and B ! A) take place above 700 ±C. By isothermal annealing, the reconfiguration rates were determined and the reconfiguration energy was calculated to EA = 2.4±0.2 eV. Since the defect is present already after low-energy electron irradiation, which mainly affects the C atom in SiC, the EH5 peak may be related to defects associated with C-vacancies or C-interstitials

Abstract: After low-energy electron irradiation of epitaxial n-type 4H-SiC, the DLTS peak amplitudes of the defects Z1/2 and EH6/7, which were already observed in as-grown layers, increased and the commonly found peaks EH1 and EH3 appeared. The bistable M-center, previously seen in high-energy proton implanted 4H-SiC, was detected. New bistable defects, the EB-centers, evolved after annealing out of the M-center, EH1 and EH3. The reconfiguration energies for one of the two EB-centers were determined to be about 0.96 eV for both transitions: from configuration I to II and from configuration II to I. Since low-energy electron irradiation (<220 keV) affects mainly the carbon atom in SiC, both the M- and EB-centers are likely to be carbon related defects.

Abstract: Several smart materials such as shape memory alloys (SMA) and electroactive polymers (EAP) have good properties in small scales and are often a good choice for tiny surface deflection applications. However they need continuous powering to keep their shape change, leading to a significant loss of energy. An interesting approach is to associate a smart material with a bistable element, which provides two stable positions without power. This action requires some energy to snap from one position to the other one. This association gives a very power-efficient solution. In this paper, we present a mechanical study on the actuation of a bistable structure, using a distributed torque actuation that is very suitable for smart materials. We provide an approach to optimize the actuation location, this allow to use less powerful and more compact actuators.

Abstract: We demonstrated a nonvolatile memory fabricated with the sandwich device structure of Al/Au nano-crystals embedded in the PVK/Al. The bi-stable conduction switching characteristic (Ion/Ioff ratio) was >1x102, depending on Au nano-crystal size. The size and distribution of Au nano-crystals were determined by the inserted Au-layer thickness between PVK layers. The size of Au nano-crystals increased with the inserted Au-layer thickness. The uniform distribution of isolated Au nano-crystals was obtained with 5 nm of the inserted Au-layer thickness.