Optimal value functions of generalized semi-infinite min-max programming on a noncompact set

In this paper, we study optimal value functions of generalized semi-infinite min-max programming problems on a noncompact set. Directional derivatives and subd-ifferential characterizations of optimal value functions are given. Using these properties, we establish first order optimality conditions for unconstrained generalized semi-infinite programming problems.     

White light-emitting diodes using blue and yellow-orange-emitting phosphors

A blue-emitting phosphor, BaMgAl₁₀O₁₇:Eu²⁺ (BAM) and a yellow-orange phosphor, Ba²⁺-codoped Sr₃SiO₅:Eu²⁺ were prepared by the solid-state reaction. Excitation and emission spectra results showed that BAM and Ba²⁺-codoped Sr₃SiO₅:Eu²⁺ can be efficiently excited by near-ultraviolet (n-UV)-visible light from 250 to 440 nm. The effects of the doped-Eu²⁺ concentration in BAM and Ba²⁺-codoped Sr₃SiO₅:Eu²⁺ on the photoluminescence were investigated in detail. White light-emitting diodes (LED) was obtained by combining n-UV LED chip (GaN-based 380 nm emitting) with BaMgAl₁₀O₁₇:0.09Eu²⁺ and 0.1Ba²⁺-codoped Sr₃SiO₅: 0.2Eu²⁺ phosphors with the characteristic of color-rendering index of 86, CIE chromaticity coordinates (x,y) of (0.3216,0.3096), and color temperature T_c of 5700 K. As the current increases, the relative intensity simultaneously increases. The CIE chromaticity coordinates (x,y) of the white LED tends to decrease. The correlated color temperature T_c increases from 4100 to 7500 K and the color-rendering index R_a increases from 82 to 87 simultaneously.     

N,N,N＇,N＇-四苄基取代方块菁染料LB膜研究

方块菁染料在有机光导材料^[1,2]、有机太阳能存储^[2,3]、光记录^[4、有机光盘中红外吸收器^[4]以及光纤识别功能薄膜等领域中有着广泛应用前景.     

Rheological Investigations in Understanding Shear‐Enhanced Crystallization of Isotactic Poly(propylene)/Multi‐Walled Carbon Nanotube Composites

A novel experimental technique to follow the crystallization processes of poly(propylene)/MWCNT composites that experience a steady shear deformation using dynamic melt rheometry is described. The effects of heterogeneous nucleation, temperature, and preshear on the crystallization behaviors were determined. A quantitative evaluation of crystallization kinetics difference between quiescent and preshear conditions could be achieved. By combining rheology with POM, we demonstrate that two different crystallization processes account for the shear‐enhanced crystallization at low and high temperatures, respectively.

     

Ricci curvature and the topology of open manifolds

In this paper, we prove that an open Riemannian n-manifold with Ricci curvature and for some is diffeomorphic to a Euclidean n-space if the volume growth of geodesic balls around p is not too far from that of the balls in . We also prove that a complete n-manifold M with is diffeomorphic to if , where is the volume of unit ball in . Received 5 May, 1997     

Complete submanifolds of manifolds of negative curvature

In this article, we give sufficient conditions for a complete non-compact submanifold in a simply connected manifold of negative sectional curvature to have only one end. We also prove some Liouville theorems for harmonic maps from the same kind of submanifolds to manifolds of non-positive curvature.     

Eigenvalues of the Wentzell–Laplace operator and of the fourth order Steklov problems

We prove a sharp upper bound and a lower bound for the first nonzero eigenvalue of the Wentzell–Laplace operator on compact manifolds with boundary and an isoperimetric inequality for the same eigenvalue in the case where the manifold is a bounded domain in a Euclidean space. We study some fourth order Steklov problems and obtain isoperimetric upper bound for the first eigenvalue of them. We also find all the eigenvalues and eigenfunctions for two kind of fourth order Steklov problems on a Euclidean ball.     

A Universal Bound for the Low Eigenvalues of Neumann Laplacians on Compact Domains in a Hadamard Manifold

 Let M be an n-dimensional simply connected Hadamard manifold with Ricci curvature satisfying and be a bounded domain having smooth boundary. In this paper, we prove that the first n nonzero Neumann eigenvalues of the Laplacian on Ω satisfy , where is a computable constant depending only on and , Ω being the volume of Ω. This result generalizes the corresponding estimate for bounded domains in a Euclidean space obtained recently by M. S. Ashbaugh and R. D. Benguria. (Received 19 May 1998; in revised form 21 September 1998)     

The interference characteristics of platform and towed body noise in shallow water for active/passive towed array sonar

The interference characteristics of towed platform noise resulted from propeller and towed body for active/passive towed array is analyzed. It is shown that, in shallow water environment, the direct wave and bottom/sea surface reflected wave will seriously affect the performance of sonar system. The formula for calculating the direction of arrival (DOA) of interference in terms of various parameters, such as array depth, length of tow cable, is derived. The effect of interference noise for the detection performance of sonar system is described. The results of system simulation provide the method for reducing the effect of these kind of interferences.     

Synergistic Effect of Phosphorus-Containing Montmorillonite with Intumescent Flame Retardant in Polypropylene

Phosphorus-containing montmorillonite (P-MMT) was successfully prepared via intercalating resorcinol bis(diphenyl phosphate) (RDP) into montmorillonite (MMT) layers, and was utilized as a synergistic agent in the polypropylene/melamine pyrophosphate/pentaerythritol (PP/MPP/PER) intumescent flame retardant (IFR) system. The synergistic effect of P-MMT and IFR was investigated by dynamic mechanical analysis (DMA), thermogravimetry (TG), limiting oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), and scanning electron microscopy (SEM). It was found that P-MMT could significantly improve the thermostability and flame retardancy of the PP/IFR composite. When 2.0 wt% P-MMT replaced the same amount of IFR in the composite, both the onset decomposition temperature (T _onset) and the maximum-rate decomposition temperature (T _max) of the PP/IFR composite were increased by more than 14°C. Meanwhile, the LOI value was increased from 29.5% to 32.5%, the UL-94 rating was enhanced from V-1 to V-0, and the heat release rate (HRR), total heat release (THR), and mass lose rate (MLR) were decreased dramatically, which proved that P-MMT had a good synergistic effect with IFR in flame retardant PP.