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The hot deformation behavior of an Al–5.7 wt.%Mg alloy with erbium was studied by compressive deformation tests in the strain rate range of 0.001–10 s −1 and temperature range of 300–500 °C. The constitutive equations were presented considering the values of A and β as a function of strain in the exponential function form. The error of predicted and measured data was less than 9%. Dynamic recrystallization was restrained by precipitate with Er and dynamic recovery dominated in the hot deformation. The mechanism of dynamic recovery was dislocation movement and the development of microstructure during deformation can be characterized by the Z parameter, and then the relationship between subgrains and deformation parameters have been also established.

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a naturally sourced polymer with good biocompatibility and potential applications in biomedical field after sterilization. Radiation sterilization technology has been extensively applied on medical products. However, for polymer-based biomedical materials, gamma irradiation can cause random chain scission on the polymer backbone. In this paper, we studied the effect of gamma irradiation on the mechanical and thermal properties of PHBHHx. The tensile strength and fracture strain of PHBHHx decreased after irradiation, while the brittleness increased after irradiation. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) results showed that the melting temperatures of irradiated PHBHHx are lower than the non-irradiated films, but the irradiated specimen shows a higher decomposition temperature than non-irradiated PHBHHx.

This paper proposes a novel online real-time assessment method based on equilibrium solution region of branch power flow. This method demonstrates the use of line stability index in order to determine the voltage stability limits in a power system. Line voltage stability indices presented in the literatures are reviewed and discussed. The shortcomings of these methods are pointed out in the face of special operation mode. A new index is deduced based on the feasible solution region of branch equations. The equations of active power and reactive power via node voltage of the branch are listed to form the equilibrium solution region. The similarities and differences between the flow direction of active power and reactive power are analyzed to determine the incidence of them to equilibrium solution. The examples show that the new index has the advantage of low computation burden, and can supply an effective analysis tool for real time on-line assessment of voltage stability in power systems.

A general and procedural algorithm for Z-matrix building is proposed in this paper. This algorithm can be accomplished by an improved search technique to choose the tree branch set (TS) and link branch set (LS) and is easily implemented for a network containing the controlled sources. The look-up table saved during the search process of TS is fully utilized to reduce the computational amount when formulating the transitional matrix MIB. During the construction of another transitional matrix MBV, the applications of different kinds of controlled sources are discussed thoroughly considering the characteristics of the current-controlled sources and voltage- controlled sources, respectively. With these two matrices, the relationships between the bus current injections, branch currents and bus voltages can easily be found. Numerical example shows that the proposed method is very effective and suitable to be used for the analysis of large-scale power systems.