合成人造金刚石的高压腔内电阻率变化研究

 通过时人造金刚石合成腔内材料电阻率变化的某些宏观规律研究，分析了在不同高温高压条件下，合成腔内所发生的相变过程。本文采用的研究方法，表明了对封闭的高温高压腔内所发生的反应从外部进行动态连续观测的可能性与价值，为研究人造金刚石成核、生长的规律提供了较好的手段。     

Regular complete permutation polynomials over $${\mathbb {F}}_{2^{n}}$$ F 2 n

Designs, Codes and Cryptography - Applications of permutation polynomials in cryptography are closely related to their cycle structures. For example, many block ciphers use permutation polynomials...     

On the Canonical Elastic Moduli of Linear Plane Anisotropic Elasticity

The linear, planar, anisotropic elastic equilibrium equations are transformed to canonical form, through linear transformations of both coordinates and unknown displacement functions, together with a linear combination of equations. Correspondingly, the six original material moduli are replaced by two canonical elastic moduli. Similar results have been reached by Olver in 1988. However, the method demonstrated in this paper is more concise and direct. As an example, the general solution to the canonical equations is obtained in the case of a pair of double roots.     

Hertzian Contact of Anisotropic Piezoelectric Bodies

The Fourier transform method is applied to the Hertzian contact problem for anisotropic piezoelectric bodies. Using the principle of linear superposition, the resulting transformed (algebraic) equations, whose right-hand sides contain both pressure and electric displacement terms, can be solved by superposing the solutions of two sets of algebraic equations, one containing pressure and another containing electric displacement. By presupposing the forms of the pressure and electric displacement distribution over the contact area, the problem is solved successfully; then the generalized displacements, stresses and strains are expressed by contour integrals. Details are presented in the case of special orthotropic piezoelectricity whose material constants satisfy six relations, which can be easily degenerated to the case of transverse isotropic piezoelectricity. It can be shown that the result gained in this paper is of a universal and compact form for a general material.Supported by the National Natural Science Foundation of China (No.10372003).     

Factors affecting the sorption of trivalent chromium by zeolite synthesized from coal fly ash

This research was initiated to determine the effects of different constituents and properties of zeolite synthesized from fly ash (ZFA) on Cr(III) sorption. The uptake of Cr(III) by ZFA was influenced greatly by pH, increasing with the increase in pH. The pH was controlled mainly by calcium-related components (especially CaCO3 and free CaO) and zeolite components in ZFAs. Sorption maximum of Cr(III) (Qm), determined by a repeated batch equilibration method, ranged from 22.29 to 99.91 mg/g for the 14 ZFAs. The Q(m) value correlated significantly with Ca-related components. The correlation coefficients were 0.9467, 0.5469, 0.7521, and 0.9195 for total Ca, CaCO3, CaSO4, and f.CaO, respectively. The Qm value was also closely related to cation-exchange capacity (r=0.6872) and specific surface area (r=0.7249). Correlation coefficients of Qm with dissociated Fe2O3 and Al2O3 were much higher than those of total Fe and total Al contents, respectively. It was suggested that, in ZFAs, zeolite and iron oxide acted as ion exchanger and adsorbent for Cr(III), respectively, while Ca components elevated the pH of the reaction system and consequently promoted ion exchange and adsorption and caused the surface precipitation of chromium hydroxide.     

Pressure Driven Structural Evolutions of 0.935(Na_(0.5)Bi_(0.5))TiO_3-0.065BaTiO_3 Lead-Free Ferroelectric Single Crystal through Raman Spectroscopy

Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Raman spectroscopy.The pressure dependence of phonon modes up to 30GPa reveals two characteristic pressures:one is at around 4.6GPa which corresponds to the rhombohedral-to-tetragonal phase transition,showing that the pressure strongly suppresses the coupling between the off-centered A-and B-site cations;the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure～13–15GPa with certain degree of order-disorder transition,evidenced by the abnormal changes of intensity and FWHM in Raman spectrum.     

New generalized cyclotomic binary sequences of period $$p^2$$

New generalized cyclotomic binary sequences of period \(p^2\) are proposed in this paper, where p is an odd prime. The sequences are almost balanced and their linear complexity is determined. The result shows that the proposed sequences have very large linear complexity if p is a non-Wieferich prime.     

Stability analysis and estimation of domain of attraction for the endemic equilibrium of an SEIQ epidemic model

This paper mainly addressed the stability analysis and the estimation of domain of attraction for the endemic equilibrium of a class of susceptible-exposed-infected-quarantine epidemic models. Firstly, we discuss the global stability of the disease-free equilibrium and the local stability of the endemic equilibrium in the feasible region D of the epidemic model, respectively. Secondly, we use a geometric approach to investigate the global stability of the endemic equilibrium in a positive invariant region \(D_s(\subset D)\). Furthermore, we estimates the domain of attraction for the endemic equilibrium via sum of squares optimization method, and obtain the optimal estimation by solving an semidefinite programming problem with sum of squares polynomial constraints. Finally, numerical simulation is examined to demonstrate the feasibility and effectiveness of the research results.