海洋激光雷达测量海中悬移质

研制了一套采用倍频YAG激光器的小型海洋激光雷达，用于测量海中悬移质浓度，2000年8月28日至9月5日，该系统安装于“东方红Ⅱ”号右舷下甲板，在渤海海区进行海中悬移质浓度现场测量，通过对18个站位的海洋激光雷达数据分析，获得的表层悬移质浓度与同步测量的海中悬移质浓度结果吻合较好。     

利用模式的对称性研究光子晶体光纤的色散

由光子晶体光纤的对称性可以得到模式分布的对称性，根据模式的对称性选择适当的展开函数，可以使计算量大大减少。计算了六角结构光子晶体光纤的色散特性，得到了波长在1．55pm处色散为零时，光子晶体光纤的结构参量所满足的方程。     

The Study of MMW and MW Attenuation Considering Multiple Scattering Effect in Sand and Dust Storms at Slant Paths

The influence of sand and dust storms on modern MMW and satellite communication systems reliability have been paid more attention to. The attenuations induced by sand and dust storms are estimated by means of Mie-theory and Rayleigh approximation, in the case of the tenuous distribution of particles. With the particle density increasing, however, these method become inadequate, the multiple scattering effects then become dominant for attenuation estimation. The attenuations considering multiple scattering effects are estimated by Monte-Carlo and four fluxes method at horizontal paths. At slant paths, based on multi-layer media model, the attenuations considering multiple scattering effects are calculated by layered Monte-Carlo method at 100, 37, 24, and 14GHz. It is shown that the multiple scattering effects should be considered at the attenuation prediction in the sand and dust storm, which the visibility is about 0.5km and smaller than 0.5km and frequency is about 20GHz. Above 30GHz, the multiple scattering effects due to sand and dust particles should be considered, as visibility is about 1km and smaller than 1km at slant paths.     

Bandwidth‐guaranteed QoS routing of multiple parallel paths in CDMA/TDMA ad hoc wireless networks

This paper investigates the issues of QoS routing in CDMA/TDMA ad hoc networks. Since the available bandwidth is very limited in ad hoc networks, a QoS request between two nodes will be blocked if there does not exist a path that can meet the QoS requirements, even though there is enough free bandwidth in the whole system. In this paper, we propose a new scheme of using multiple paths between two nodes as the route for a QoS call. The aggregate bandwidth of the multiple paths can meet the bandwidth requirement of the call and the delays of these paths are within the required bound of the call. We also propose three strategies by which to choose a set of paths as the route, namely, shortest path first (SPF), largest bandwidth first (LBF), and largest hop‐bandwidth first (LHBF). Extensive simulations have been conducted to evaluate the performance of the three strategies in comparison with a traditional single path routing algorithm. The simulation results show that the proposed multiple paths routing scheme significantly reduces the system blocking rates in various network environments, especially when the network load is heavy. Copyright © 2005 John Wiley & Sons, Ltd.     

Architectural Control of Hierarchical Nanobelt Superstructures in Catanionic Reverse Micelles

BaXO₄ (X = Mo, W) nanobelts and a variety of hierarchical superstructures assembled from the nanobelts have been synthesized in a catanionic reverse‐micelle system. The effects of various factors, such as the mixing ratio (r) between the anionic and cationic surfactants, the temperature, and the presence of polymeric additives, on the formation of the nanobelts and their hierarchical assembly have been examined in detail. In particular, r has been shown to be powerful in modulating the formation and assembly of the BaMoO₄ and BaWO₄ nanobelts. Architectural control of the penniform nanobelt superstructures has been readily achieved by changing the experimental parameters. A plausible two‐stage growth mechanism has been proposed for the formation of penniform BaXO₄ nanobelt superstructures in catanionic reverse micelles.     

关于组合最优化理论的多媒体教学实践

本文讨论和分析了开发组合最比化理论系列课程多媒体课件的基本认识、课件的主要特色和体会，并提出了使用多媒体课件中应注意的问题．     

一个来自振动理论反问题的矩阵方程

§ 1　ＩｎｔｒｏｄｕｃｔｉｏｎＬｅｔＲｎ×ｍｄｅｎｏｔｅｔｈｅｒｅａｌｎ×ｍｍａｔｒｉｘｓｐａｃｅ ,Ｒｎ×ｍｒ ｉｔｓｓｕｂｓｅｔｗｈｏｓｅｅｌｅｍｅｎｔｓｈａｖｅｒａｎｋｒ ,ＯＲｎ×ｎｔｈｅｓｅｔｏｆａｌｌｎ×ｎｏｒｔｈｏｇｏｎａｌｍａｔｒｉｃｅｓ,ＳＲｎ×ｎ(ＳＲｎ×ｎ≥ ,ＳＲｎ×ｎ>)ｔｈｅｓｅｔｏｆａｌｌｎ×ｎｒｅａｌｓｙｍｍｅｔｒｉｃ (ｓｙｍｍｅｔｒｉｃｐｏｓｉｔｉｖｅｓｅｍｉｄｅｆｉｎｉｔｅ ,ｐｏｓｉｔｉｖｅｄｅｆｉｎｉｔｅ)ｍａｔｒｉｃｅｓ.ＴｈｅｎｏｔａｔｉｏｎＡ>0 (≥ 0 ,<0 ,≤ 0 )ｍ…     

On the coupled NBEM and FEM for a class of nonlinear exterior Dirichlet problem in R 2

In this paper, based on the natural boundary reduction advanced by Feng and Yu, we couple the finite element approach with the natural boundary element method to study the weak solvability and Galerkin approximation of a class of nonlinear exterior boundary value problems. The analysis is mainly based on the variational formulation with constraints. We prove the error estimate of the finite element solution and obtain the asymptotic rate of convergence. Finally, we also give a numerical example.

     

Ergodicity for the Dissipative Boussinesq Equations with Random Forcing

We study the stationary measure for the two-dimensional Boussinesq equation with random forcing. We prove the ergodicity for the two-dimensional stochastically forced Boussinesq equation. We also study the Galerkin truncations of the three-dimensional Boussinesq equations under degenerate stochastic forcing. We follow closely the previous results on the stochastically forced Navier–Stokes equations.     

Tunable microlens arrays using polymer network liquid crystal

A tunable-focus microlens array based on polymer network liquid crystal (PNLC) is demonstrated. The PNLC was prepared using an ultraviolet (UV) light exposure through a patterned photomask. The photocurable monomer in each of the UV exposed spot forms an inhomogeneous centro-symmetrical polymer network which acts as a lens when a homogeneous electric field is applied to the cell. The focal length of the microlens arrays is tunable with the applied voltage.