Phase and group velocity matching equations of second harmonic generation are reconsidered for 1D photonic crystals to analyze an induced structure restriction. A multiplicity of solutions is found through a numerical computation, which separates the restricted structure parameters into infinite units. The local and global characteristics of the restriction on refractive indices and material lengths are discussed in detail as well. The analysis shows that increasing either the dispersion of the nonlinear material or the thickness of a single layer will require a larger refractive index contrast.
In this work, a novel trimeric octadecyl zwitterionic surfactant (TOCC) was successfully synthesized. TOCC was compounded with sodium salicylate (NaSal) for an optimized formulation to form viscoelastic micelles. The effects of NaSal concentration, pH, and temperature on the rheological properties of TOCC and TOCC/NaSal micelle solutions were investigated. The flow curves for both TOCC and TOCC/NaSal micelle solutions can be fitted with the Carreau–Yasuda model. Zero shear viscosity of TOCC/NaSal micelle solution increased and then decreased with increasing NaSal concentration, and the same trend was observed for viscoelasticity. Some micelle solutions exhibited significant thixotropy with stress overshoot. The optimal composition of the TOCC/NaSal micelle solution obtained was 5.0/0.5 wt%. Frequency sweep in the form of Cole–Cole plots indicated that the viscoelastic modulus of the TOCC/NaSal micelle solution fitted the Maxwell model at low and medium frequencies. With increasing pH, 5.0 wt% TOCC micelle solution had the maximum zero shear viscosity at pH = 6.9. The steady‐state viscosities of different concentrations of TOCC micelle solutions reached their maximum at neutral conditions (pH = 6.5 ~ 7.0). Viscoelastic modulus of 5.0 wt% TOCC and TOCC/NaSal (5.0/0.5 wt%) micelle solutions decreased with increasing temperature, and thermal thixotropy was observed in both micelle solutions. The novel TOCC and TOCC/NaSal micelle solutions enrich the variety of trimeric surfactants and viscoelastic micelle solutions. This study provides a rheological reference for the applications of viscoelastic trimeric surfactants in smart materials and oil fields.
Using samples of A-share listed non-financial companies of 2015, This paper summarizes the research methods of inefficient investment and an effective method is chosen to measure the listed companies in China. The research in this paper shows that: China's listed companies generally exist inefficient investment and there are more companies with less investment, but the scale of inefficient investment is lager in overinvestment. In addition, this paper also provides some suggestions on how to reduce inefficient investment.
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