Search

In this work, a dynamic S-box is designed based on the chaotic neural network using the memristor model of LiNbO3 (LNO) single crystalline thin film. The LNO memristor, which shows good repeatability and the characteristic of gradual resistance change, is used as the self-feedback weight in the Transient Chaotic Neural Network (TCNN) model to form a chaotic neural network. Double pseudo-random digits are generated for dynamically adjusting the S-box elements according to the weight function. The experimental results show that the proposed design can achieve physical unclonability and has better nonlinearity and differential uniformity.

Iron (Fe) based alloys are widely used in the nuclear industry because the activation of Fe is low and the irradiation data for Fe alloys is abundant. The interaction between helium (He) atoms and defects in Fe alloys is an important issue in fusion reactors, since the rate of He generation is high. In the present study, well-annealed Fe specimens were cold-rolled until the original thickness was reduced by 10% or 40%, and then annealed at 673 or 723 K for 1 h, respectively, to annihilate the vacancy clusters formed during cold rolling. He atoms were implanted at 100 eV without causing displacement damage in the annealed cold-rolled samples, which contained only dislocations. Upon He implantation, the yield stress (lower yield stress) and tensile strength decreased, and the total elongation increased. The former effect became stronger with increasing deformation (elongation induced by cold rolling from 10% to 40%), whereas the latter became weaker.

Neutron irradiation-induced vacancy defects in F82H model alloys were studied using positron lifetime measurements. A comparison between the results from neutron irradiation and our previous electron irradiation in F82H model alloys was conducted. The results showed that Cr has a consistent effect on void swelling resistance. The void swelling suppression by Cr was explained using the configuration trapping model. However, for the W, V and Ta solute effects, the results of two types of irradiation support the solute and dislocation interaction model. The effects on metal carbides (M23C6) were investigated using neutron irradiation at 363 K and electron irradiation. For neutron irradiation, the solute effect may be the dominating factor compared to the effects of the M23C6. Solute depletion caused by metal carbides can explain the difference.

Bulk materials with the general formula of Mn 3 (Cu 0.6 Nb x Ge 0.4 − x )N ( x = 0.05, 0.1, 0.15, 0.2, 0.25), Mn 3 (Cu 0.6 Ge 0.4 )N and Mn 3 (Cu 0.7 Ge 0.3 )N were fabricated by mechanical ball milling and solid state sintering. Their thermal expansion coefficients and electrical conductivities were investigated in the temperature range of 80–300 K. It is found that the temperature interval of negative temperature expansion behavior is about 95 K in the samples of Mn 3 (Cu 0.6 Nb 0.15 Ge 0.25 )N and Mn 3 (Cu 0.6 Nb 0.2 Ge 0.2 )N, which is twice as large as that of Mn 3 (Cu 0.7 Ge 0.3 )N. The negative thermal expansion of Mn 3 (Cu 0.6 Nb 0.15 Ge 0.25 )N can reach to − 19.5 × 10 −6 K − 1 in the temperature range of 165 to 210 K. The electrical conductivity of this series materials is in a level of about 2.5 × 10 6 (Ω m) − 1 .

The microstructural evolution of epitaxial SrRuO3 thin films from ambient temperature (about 293K) to about 900K has been studied by in-situ transmission electron microscopy. Upon heating from the ambient temperature, the intensities of h, k, 2n+1 and h, -h+2n+1, 0 reflections in selected-area electron diffraction patterns decrease with increasing temperature. Two structural phase transitions were observed at about 673and about 783K, revealed by the vanishing of the h, k, 2n+1 and h,-h+2n+1, 0 reflections respectively. The examination of electron diffraction patterns along several different zone axes, taking into account the possible tilting configurations of RuO6 octahedra, indicates that, upon heating, the orthorhombic structure of SrRuO3 transforms into a tetragonal structure at about 673K, and further transforms into a cubic structure at about 783K. Possible structural models for the high-temperature phases are considered.