带对流项的非线性椭圆型问题爆炸解的存在性与渐近行为

设Ω是RN（N≥3）中的C2有界区域,对带负对流项的情形,对更广泛的非线性项,构造一种新型的非线性变换将爆炸解问题,转化成等价的带奇异项的Dirichlet问题,应用极大值原理得到了爆炸解问题解的最小爆炸速度.应用三种摄动方法,结合上下解方法、二阶椭圆型偏微分方程的估计理论得到了爆炸解的存在性.特别允许非线性项的系数不仅在Ω的内部子区域恒为零而且在Ω上可适当无界.随后再应用摄动方法,将所得结果推广到RN,得到了整体爆炸解的存在性以及在无穷远附近的最小爆炸速度.而对带正对流项的情形,对更广泛的非线性项,构造爆炸上下解u和u在Ω上满足u≤u,得到了爆炸解u的存在性且在Ω上满足u≤u≤u.     

An identification problem for a conserved phase‐field model with memory

This paper is devoted to recovering a scalar memory kernel in a conserved phase‐field model. For such a problem local in time existence and uniqueness results are proved. The technique used allows to show also the continuous dependence on the kernel of the solution to the direct problem. Copyright © 2005 John Wiley & Sons, Ltd.     

债券利率风险分析

本给出了广义久期模型，并证明了参数变化对久期影响的结论。这些分析有助于基金经理们对期限结构影响的认识，进而帮助他们进行投资组合的选择。     

Translation of helical chirality from polymer into monomer: supramolecular polymerization of a chirality-memory molecule with an asymmetric Pd(II) complex

A chirality-memorizing saddle-shaped porphyrin (1_2H) with 3,5-dipyridylphenyl side arms at the opposite meso positions underwent supramolecular polymerization in CH₂Cl₂ with a chiral Pd(II) complex of 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (Pd^II(BINAP)), forming a ladder-shaped polymer (3_2H) with a prevailing one-handed helical chirality. When this polymer was poured into AcOH containing 1,3-bis(diphenylphosphino)propane (DPPP) as a decomplexing agent, 3_2H was depolymerized in a stereochemically retentive way to give optically active 1_2H, hydrogen-bonded with AcOH. Although a cyclodimeric reference of 3_2H, formed from 2_2H having two 3-pyridylphenyl meso substituents in conjunction with Pd^II(BINAP), behaved similar to 3_2H, the translation efficiency of helical chirality was lower than that in the case with 3_2H.     

Influence of mass-transfer effect on isoconversional calculations

A theoretical simulation of the influence of mass-transfer effect on the kinetics of solid–gas reactions has been carried out. The influence of mass-transfer phenomena on the shape of the thermoanalytical curves and on the apparent activation energy, calculated by advanced isoconversional methods (Vyazovkin method) is discussed. The Vyazovkin equation has been adapted to CRTA data and, a modification of this equation, to account for pressure correction term in the reaction rate was achieved. To check the equations developed in this paper, the standard isoconversional procedure has been modified, instead of a set of experiments performed under different heating rates (or reaction rates C in the case of CRTA) for a given conversion we use a set of experiments under different pressure of the gas self-generated in the reaction at one heating rate β (or reaction rate C), respectively.The results obtained allow for trustworthy estimates of the activation energy from advanced isoconversional method in reaction systems whose kinetics are affected by the pressure of the gases self-generated by the reaction. Theoretical considerations are verified on simulated non-isothermal TG, and non-isothermal non-linear controlled rate thermal analysis (CRTA) data. Experimental data of calcite have been used.     

Study on poly(ε‐caprolactone)‐based shape memory copolymer fiber prepared by bulk polymerization and melt spinning

In this paper, a poly(ε‐caprolactone) (PCL)‐based shape memory polyurethane fiber was prepared by melt spinning. The shape memory switching temperature was the melting transition temperature of the soft segment phase mainly composed of PCL at 47°C. The mechanical properties especially shape memory effect were explicitly characterized by thermomechanical cyclic tensile testing. The results suggest that the prepared fiber has shape memory effects. The prepared 40 denier shape memory fiber had a tenacity of about 1.0 cN/dtex, and strain at break 562–660%. The shape fixity ratio reached 84% and the recovery ratio reached 95% under drawing at high temperature and thermal recovery testing.¹ Finally, the fiber thermal/mechanical properties were measured using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Copyright © 2007 John Wiley & Sons, Ltd.     

Maximum of the modulus of kernels in Gauss-Turán quadratures

We study the kernels in the remainder terms of the Gauss-Turán quadrature formulae for analytic functions on elliptical contours with foci at , when the weight is a generalized Chebyshev weight function. For the generalized Chebyshev weight of the first (third) kind, it is shown that the modulus of the kernel attains its maximum on the real axis (positive real semi-axis) for each . It was stated as a conjecture in [Math. Comp. 72 (2003), 1855-1872]. For the generalized Chebyshev weight of the second kind, in the case when the number of the nodes in the corresponding Gauss-Turán quadrature formula is even, it is shown that the modulus of the kernel attains its maximum on the imaginary axis for each . Numerical examples are included.

     

Two-way shape memory behavior of styrene-based bilayer shape memory polymer plate

In this work, a bilayer shape memory polymer (SMP) composite plate with two-way shape memory behavior is simulated, in which two types of styrene-based SMPs with well-separated glass transition temperatures are assembled in parallel. The finite element (FE) software ABAQUS is selected to exhibit the two-way shape memory effect during the shape recovery step and the Generalized Maxwell Model with the WLF equation is applied to characterize the temperature-dependent properties of the SMP bilayer plates. The effect factors of axial predeformation, thermal expansion coefficient and plate thickness are all considered for the two-way shape memory behavior of the styrene-based bilayer SMP plate. After that, a smart gripper composed of four SMP composite plates is proposed to realize grabbing and releasing functions for one-step and staged heating recovery. The FE results provide some necessary theoretical guidelines for future soft smart structural designs and optimization.     

Shape memory effects of poly(ethylene terephthalate-co-ethylene succinate) random copolymers

Random copolymers based on terephthalate acid, succinic acid and ethylene glycol, with thermally induced shape memory, were synthesized via melt polycondensation. The chemical structures of these poly(ethylene terephthalate-co-ethylene succinate) copolymers (PET-co-ES) were ascertained by ¹H NMR spectroscopy. The thermal and viscoelastic characteristics of these copolymers were studied in terms of the succinic acid content using differential scanning calorimetry and dynamic mechanical analysis. The shape memory effects of the copolymers were examined using the strain test. The experimental results suggested that all copolymers exhibited shape memory above the glass transition temperature and that the highest shape recovery rate was 90%. The shape recovery rates of all test samples declined with the number of cycles. This decrease in the shape recovery rate may result from the change in the degree of polymer orientation and/or crystallinity during repeated testing.