关于多项式系数微分方程复振荡理论的两个结果

本文证明了：如果ａ_ｋ－ｊ（ｊ＝１，…，ｋ）为多项式，ｄｅｇａ_ｋ－ｊ＝ｎ_ｋ－ｊ，存在某个ａ_ｋ－s（１≤ｓ≤ｋ）满足：当１≤ｊ＜ｓ时，ｎ_ｋ－ｊ／ｊ≤ｎ_ｋ－s／ｓ；当ｓ＜ｊ≤ｋ时，ｎ_ｋ－ｊ＜ｎ_ｋ－s－（ｊ－ｓ）．如果Ｆ≠０是整函数且满足σ（Ｆ）＝β＜（ｎ_ｋ－s＋ｓ）／ｓ，那么微分方程ｆ^（ｋ）＋ａ     

A global optimization design for quasi-optics power combiner of 3mm wave solid-state sources

This paper describes a global optimization design for quasi-optics power combiner of solid-state millimeter-wave sources. The operating frequency is about 100 GHz and the oscillating sources are GaAs Gunn diodes. The source-array plane is a matrix consisting of NxN (N=3,5, ..., 2k+1, where k is positive integer) diodes. The radio frequency power of the combiner is from threefold to sevenfold larger than the sum total of the single diodes power. The global optimums of the array and the location in the cuvity of the suorce-array plane will be given by a global optimizition method.     

Solitary wave solutions and cnoidal wave solutions to the combined KdV and mKdV equation

This paper presents a mapping approach for the construction of exact solutions to the combined KdV and mKdV equation. There exist two types of soliton solutions which will reduce back to those of the KdV and mKdV equations in some appropriate limits. Four types of the general cnoidal wave solutions are also obtained.     

Continuous preparation of decorated nano zinc oxide organic sols with intense luminescence

A sort of decorated nano ZnO organic sols have been successively prepared by pulsed laser ablation at the interface of ZnO target and a flowing liquid containing polymers. It is found that the decorated nano ZnO ethanol sols, the decorated nano ZnO-PS (polystyrene) cyclohexane sols and the decorated nano ZnO-PMMA (polymethyl methacrylate) ethyl butyrate sols all have strong fluorescence emission at 329 nm and 411 nm, 308 nm and 317 nm, and at 330 nm and 400 nm, respectively. The results show the decorating for nano ZnO will intensely affect their luminescence, and the wavelength and intensity of luminescence can be adjusted or controlled by the different decoration.     

Synthesis of grafted poly(p‐phenyleneethynylene) with energy donor–acceptor architecture via atom transfer radical polymerization: Towards nonaggregating and hole‐facilitating light‐emitting material

In this contribution, we demonstrate a new effective methodology for constructing highly efficient and durable poly(p‐phenyleneethynylene) (PPE) containing emissive material with nonaggregating and hole‐facilitating properties through the introduction of hole‐transporting blocks into the PPE system as the grafting coils as well as building the energy donor–acceptor architecture between the grafting coils and the PPE backbone. Poly(2‐(carbazol‐9‐yl)ethyl methacrylate) (PCzEMA), herein, is chosen as the hole‐transporting blocks, and incorporated into the PPE system as the grafting coils via atom transfer radical polymerization. The chemical structure of the resultant copolymer, PPE‐g‐PCzEMA, was characterized by NMR and gel permeation chromatography, showing that the desirable copolymer was obtained with the narrow polydispersity. The increased thermal stability of PPE‐g‐PCzEMA was confirmed by thermogravimetric analysis and differential scanning calorimetry along with its macroinitiator. The optoelectronic properties of this copolymer were studied in detail by ultraviolet‐visible absorption, photoluminescence emission and excitation spectra, and cyclic voltammogram (CV). The results indicate that PPE‐g‐PCzEMA exhibits the solid‐state luminescent property dominated by individual lumophores, and also the energy transfer process from the PCzEMA blocks to the PPE backbone with a relatively higher energy transfer efficiency in the solid‐state compared to that of the solution state. Additionally, the hole‐injection property is greatly facilitated due to the presence of PCzEMA, as confirmed by CV profiles. All these data indicate that PPE‐g‐PCzEMA is a good candidate for use in optoelectronic devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3776–3787, 2007     

Hydroxyapatite coating on porous silicon substrate obtained by precipitation process

Hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ (HAP) is known as a bioactive and biocompatible material, HAP coatings were used to improve the biocompatible of substrate by many researcher, In this work, HAP thin films on porous silicon (PS) substrates have been prepared by aqueous precipitation method with rapid thermal annealing (RTA) processes. The HAP films had been prepared under the annealing temperature ranging from 300 to 1000 °C. By the measurement of X-ray diffraction (XRD), it was found that for the crystallinity optimization, the heat-treatment at 850–950 °C for 1 h would be favorable. Atomic force microscopy (AFM) and scanning electron microscope (SEM) measurements reveal a dense and smooth surface of the HAP film, and tightly adherence of the coating on porous silicon substrate after sintered. Thus, by this method, porous silicon could be increased its bioactivity and so that could be used in the biomedical area.     

Mode Coupling in Single-Mode Helical Fibres Under Perturbations

The mode coupling in a helical fibre with a circular cross-section undergoing perturbations is investigated in the Serret-Frenet frame. The coupled-mode equations have been derived and are compared with the conventional ones. Applying the coupled-mode equations to a helical fibre with an elliptical core deformation, we obtained, for the first time, a rigorous analysis of the transmission characteristics of the fibre. The numerical examples show that the mode ellipticity and elliptical birefringence increase as the core ellipticity increases and also vary as the pitch or the core offset change.     

The variational Lyapunov function and strict stability theory for differential systems

In this paper, we investigate strict stability of differential systems by variational Lyapunov function. We obtain some sufficient conditions and comparison theorems.     

Full-Wave Analyses for a Multi-Layered Microstrip Patch Antenna

This paper describes numerical modelling of a dual band multi-layered microstrip patch antenna operating at 35GHz on an in-house semi-insulating GaAs substrate. The simulated and measured resonant frequencies at both lower and upper resonant frequencies will be compared to check the accuracy of the different numerical modelling techniques.