Effect of Cerium on the Properties of CuPNiSn Amorphous Alloys

CuPNiSn amorphous alloys are good brazing materials at medium temperature for replacement of silver bearing brazing materials.The crystallization temperature,wettability,tensile strength of Cu-Cu joints and the microstructure of joints for three compositional series are reported.Some rare earth elements were added in two series.It has been found that grains are refined and the tensile strengths increase as in- creasing rare earth content.The results also show that the brittle fracture turns to plastic one for the joints with reducing amount of(Ni+Sn),and the tensile strength is increased.

Theoretical Analysis of the Fluctuation Theorem Applied to Electric Circuits

We carry out a theoretical analysis of the fluctuations in the Johnson–Nyquist noise in an RC electric circuit being driven by a non-ideal constant current source. Using the appropriate Langevin equation, we derive the fluctuation theorem for the system. This analysis exhibits some interesting features. Firstly, the average of the dissipation function is not necessarily just an instantaneous entropy production, i.e. the work being done on the circuit by the external power source divided by the ambient temperature. Secondly, by appropriate selection of the values for the circuit components,the transient response of the system can be made identical to the nonequilibrium steady state response. In the limit of an ideal current source, the average of the dissipation function reduces to the entropy production. Our analysis accurately reproduces published experimental results.

Topological and dynamical phase transitions in the Su–Schrieffer–Heeger model with quasiperiodic and long-range hoppings

Disorders and long-range hoppings can induce exotic phenomena in condensed matter and artificial systems.We study the topological and dynamical properties of the quasiperiodic SuSchrier-Heeger model with long-range hoppings.It is found that the interplay of quasiperiodic disorder and long-range hopping can induce topological Anderson insulator phases with nonzero winding numbers ω=1,2,and the phase boundaries can be consistently revealed by the divergence of zero-energy mode localization length.We also investigate the nonequilibrium dynamics by ramping the long-range hopping along two different paths.The critical exponents extracted from the dynamical behavior agree with the Kibble-Zurek mechanic prediction for the path with W=0.90.In particular,the dynamical exponent of the path crossing the multicritical point is numerical obtained as 1/6~0.167,which agrees with the unconventional finding in the previously studied XY spin model.Besides,we discuss the anomalous and non-universal scaling of the defect density dynamics of topological edge states in this disordered system under open boundary condictions.