吸流管道动力学模型的研究现状与展望

围绕吸流管道的稳定性与振动问题,对近年来的主要研究工作加以综述并提出预测,其中包括运动方程的归纳与讨论、管道自由端口处的流固耦合理论、定常流速下吸流管道的稳定性机理以及今后值得进一步研究的某些问题.     

Dual-wavelength nonvolatile holographic storage

A simple, convenient and effective way is demonstrated to reduce the field losses of the reconstructed image in the dual-wavelength nonvolatile holographic storage by adding a cylindrical lens in the holographic recording configuration. The experimental results show that this technique makes the dual-wavelength nonvolatile holographic storage compact and practical.     

Methods of rapid orbit forecasting after maneuvers for geostationary satellites

A geostationary (GEO) satellite may serve as a navigation satellite, but there is a problem that maneuvers frequently occur and the forces are difficult to model. Based on the technique of determining satellite orbits by transfer, a predicted orbit with high accuracy may be achieved by the method of statistical orbit determination in case of no maneuver force. The predicted orbit will soon be invalid after the maneuver starts, and it takes a long time to get a valid orbit after the maneuver ends. In order to improve ephemeris usability, the method of rapid orbit forecasting after maneuvers is studied. First, GEO satellite movement is analyzed in case of maneuvers based on the observation from the orbit measurement system by transfer. Then when a GEO satellite is in the free status just after maneuvers, the short arc observation is used to forecast the orbit. It is assumed that the common system bias and biases of each station are constant, which can be obtained from orbit determination with long arc observations. In this way, only 6 orbit elements would be solved by the method of statistical orbit determination, and the ephemeris with high accuracy may be soon obtained. Actual orbit forecasting with short arc observation for SINOSAT-1 satellite shows that, with the tracking network available, the precision of the predicted orbit (RMS of O-C) can reach about 5 m with 15 min arc observation, and about 3 m with 30 min arc observation. Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA12Z322), the National Basic Research Program of China (Grant No. 2007CB815503), and the West Light Program of Chinese Academy of Sciences (Grant No. 2007LH01)     

Influence of permutizers of subgroups on the structure of finite groups

A group G is said to satisfy the maximal permutizer condition if the permutizer of any maximal subgroup M of G in G, P_G(M), is G. In this paper, we characterize the supersolubility of finite groups by using the maximal permutizer condition. We also get some results for when both G/N and N are supersoluble, which implies that G is supersoluble. Our results unify or generalize some known results.     

Fracture in Ceramic-Matrix Composites Reinforced with Strongly Bonded Metal Particles

The resistance of a ceramic matrix composite to the cleavage cracking across a field of strongly bonded, uniformly distributed metal particles is studied. The crack trapping and bridging effects of the metal particles are analyzed by means of calculating the strain energy and the traction work. An explicit expression for the critical energy release rate as a function of particle volume fraction has been obtained. The fracture resistance is independent of elastic properties of the matrix and the sample geometry and is predominantly determined by the size/spacing ratio of the particles. It is shown that the theoretical curves agree with experimental data quite well. The methodology developed in this article can be used in studying the fracture resistances of composites with high filler contents and irregular filler geometries.__________Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 3, pp. 303–318, May–June, 2005.     

分块半相依线性回归模型的参数估计

考虑一般的分块半相依线性回归（SUR）模型及其相应的简约模型，给出简约模型下未知回归系数及其可估函数的协方差改进估计仍是分块SUR模型下相应参数的协方差改进估计的一个充要条件．     

Polyplatinayne/polyoxometalate composite Langmuir‐Blodgett films: Preparation,structural characterization,and potential optoelectronic applications

A new family of organometallic/inorganic composite Langmuir‐Blodgett (LB) films consisting of rigid‐rod polyplatinayne polymer ([Pt‐T(OMe‐Fl)T]_∞ or [Pt‐T(F‐Fl)T]_∞, where the triplet bonds are abbreviated by T, and fluorene ring by Fl) as the π‐conjugated organometallic molecule, polyoxometalate (POM, POM = K₃PMo₁₂O₄₀, H₃PW₁₂O₄₀, or H₆P₂W₁₈O₆₂) of the Keggin and Dawson structures as the inorganic component, and dimethyldioctadecylammonium bromide (DODA) or a mixture of octadecanoic acid (OA) and docosanoic acid (DA) as the auxiliary film‐forming agent were prepared and characterized by π–A isotherms, UV–Vis absorption spectra, photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low‐angle X‐ray diffraction. Our experimental results indicate that steady, even, and ordered Langmuir and LB films are formed in pure water and polyoxometalate subphases. It was shown that the POM molecules are probably embedded inside the polyplatinayne molecules in the LB film structure and they can quench the luminescence of the Pt polyyne. These Pt‐polyyne based LB films display interesting electric conductivity behavior. [Pt‐T(OMe‐Fl)T]_∞/DODA/HPW₁₂ monolayer film shows a good electrical conductivity, and the tunneling current amounts to ±100 nA when the voltage is set at ±8 V. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3193–3206, 2008     

Luminescent polymeric hybrids functionalized by β-diketone with silicon-oxygen networks and carbon chains: Assembly and characterization

2-Thenoyltrifluoroacetone (TTA) was grafted onto the coupling agent 3-(triethoxysilyl)-propyl-isocyanate to construct the precursor I (TTA-Si), and polymer precursors II (PVPD, PMAA and PVPDMAA) were synthesized through the addition polymerization reactions. Then precursors I and II have coordinated to the rare-earth ions with the carbonyl, carboxyl group or nitrogen atom, respectively, and after hydrolysis and copolycondensation sol-gel process, the three kinds of polymeric hybrids were obtained. FTIR, ultraviolet-visible diffuse reflection and fluorescence absorption spectra, electronic micrographs, room-temperature X-ray diffraction patterns and TG plots were characterized and the results reveal that the hybrid materials showed uniformity in the microstructure, efficient intramolecular energy transfer system and excellent characteristic emission of terbium ions under UV irradiation.     

应用GC-MS/MS技术检测水果蔬菜中22种残留农药

目前,水果蔬菜生产中存在严重的滥施农药情况.水果蔬菜中常含有多种类型的残留农药,品种复杂多样.