This paper proposes a multi-attractor period multi-scroll chaotic system and a secondgeneration current-controlled current conveyor (CCCII) with a wide tunable range of intrinsic resistance. The newly proposed multi-attractor period multi-scroll chaotic system is constructed by this CCCII. The proposed chaotic system can generate single-attractor period, double-attractor period, three-attractor period, and even more attractor period multi-scroll. The four-dimensional state equation of the chaotic system contains four nonlinear functions for generating multi-attractor period multi-scroll chaos. Since the intrinsic resistance of the CCCII can be adjusted by external voltages or currents, the multi-attractor period multi-scroll chaotic integrated circuit based on the proposed CCCII have a tunable characteristic. It is worth noting that a chaotic integrated circuit has been implemented completely using current signals instead of voltage signals, and more interestingly, it does not contain any passive resistor. The dynamic characteristics of the multi-attractor period multi-scroll chaotic system are given. The circuit designs of the CMOS CCCII and the corresponding chaotic circuit are made in detail. We conduct the numerical and circuit simulations of the proposed chaotic system and the integrated circuit implementation of the chaotic circuit based on the CMOS CCCII. The correctness of the CCCII circuit and the chaotic system are proved through hardware experiments. The comparison between the implementation scheme of the chaotic circuit in this paper and several reported chaotic circuits is conducted. INDEX TERMS Chaotic integrated circuit, CMOS CCCII, current mode, intrinsic resistance-tunable, multi-attractor period, multi-scroll, passive resistor.
Chiral materials are usually the key to the separation of chiral membranes. In this work, we propose a new strategy that chiral porous graphene membrane can be fabricated from nonchiral porous graphene by mechanical stirring to induce vortex structure. Porous graphene with controlled, nanosized pores was synthesized by a newly designed, one-pot process directly from graphite as opposed to graphene oxide. Then porous graphene was immobilized on ultrafiltration membrane through filtering while stirring to form porous graphene membrane, which was applied for enantioselective separation toward DL-amino acids: for example, the separation factor of L-/D-phenylalanine reached 4.76. Interestingly, we first observed that the front and back sides of the porous graphene membrane exhibited opposite optical activities.
It’s necessary to calculate and analyze the strength of the pump impeller for the safe operation of the pump. In this paper, the impeller strength of a two-way full-adjust horizontal axial-flow pump in a domestic pump station under forward pumping conditions was calculated by using the unidirectional fluid-structure interaction method; it means loading the blade surface water pressure calculating from CFD software CFX as structure surface loads to the blade, and then calculating the strength of the impeller using finite element software ANSYS ; the strength of the impeller was calculated under different blade rotating angle conditions. Through the calculation, we has got static stress and deformation distribution in the impeller. The results show that under each blade rotating angle, the maximum static stress always increases with lift increasing; the maximum static stress occurs at the junction of the blade and hub; the stress concentration also occurs in there prone to cause fatigue failure; maximum deformation of the blade occurs in the leading edge close to the rim; the maximum static stress is far less than yield strength of the material that the static stress can not cause cracks.
We present a simple theoretical model study of negative ion conversion in neutral oxygen atom grazing scattering from a LiF(100) surface. A comparison of the calculated relative contributions of the image interaction and the Mott–Littleton polarization interaction to the electron-capture reaction energy defect implies that the image interaction can significantly reduce the electron-capture energy defect, in turn drastically increasing the electron-capture probability. This property means that the image interaction can play an important role in negative ion formation. Owing to the incorporation of detachment of the affinity electron of the formed negative ions by Coulomb repulsive barrier tunneling during the interaction with surface anion sites, our present theoretical results can well reproduce the experimental negative ion yield in the whole velocity range. Moreover, a comparison of the magnitudes of the image interaction for different optical limit dielectric constants reveals that a larger optical limit dielectric constant corresponds to a larger image interaction. This large image interaction can obviously reduce the energy defect of valence band electron capture, in turn increasing the electron-capture probability and finally leading to a significant increase in the negative ion yield in the scattered beam. This result implies that the selection of an ionic crystal with a large optical limit dielectric constant can pave the way to achieving a high negative ion yield and promote its various technical applications.
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