基于Welch Costas序列的最佳跳频码结构及其在OFDM系统中的应用

讨论了OFDM系统中跳频码设计的问题,建立了含有一个间隙行的Welch Costas序列的结构理论,深入研究了含有一个间隙行的Welch Costas序列的代数结构、构造方法和自(互)相关特性,并证明了相关的定理.探索了用含有一个间隙行的Welch Costas序列设计OFDM系统中跳频图样的方法,举例说明了如何设计跳频码和怎样将跳频码分配给OFDM系统中的用户.用含有一个间隙行的Welch Costas序列设计跳频码能获得理想的自相关特性,并且当无线通信系统中多普勒频移受限时能获得极佳的互相关性能.     

NPSP:一种高效的序列模式增量挖掘算法

提出了一种称为“异构树”的数据结构,采用一套编号规则对异构树的分支进行编号,使具有相同编号的分支代表相同的候选序列,编号不同的分支代表不同的候选序列,极大地简化了候选集计数过程,在此基础上提出了具有增量挖掘功能的序列模式高效挖掘算法NPSP,并从理论分析和实验两方面证明了其挖掘结果集的完备性和算法的高效性．     

遵义丁台镍钼矿床稀土元素地球化学特征及其地质意义

对丁台镍钼矿床中的矿层及其顶、底板岩石进行系统采样,测试分析样品中的稀土元素含量,探讨稀土元素地球化学特征.研究结果表明,矿床中的∑REE变化大,轻、重稀土均富集,富集程度相近,分馏程度不明显;δCe=0.54～0.79,平均0.68,δEu=1.02 ～2.61,平均1.45;La/Ce=0.60 ～0.93.这些特征说明矿床形成于气候干燥条件下的海相热水沉积还原环境.∑REE-La/Yb图解反映成矿物质具有多来源特征.     

A study on the distribution of adsorbed nanoparticles

We use Monte Carlo simulation to calculate the distributions of particles under adsorption force near planar and cylindrical surfaces,respectively.Both hard sphere interaction and repulsive Yukawa (screened coulomb) interaction are employed in our simulations.We study the influence of the inter-particle potentials.The difference between the MC simulation results and the analytical results of ideal gas model shows that the interaction between particles plays an important role in the density distribution under external fields.Moreover,the 2-dimensional constructions of particles close to the surface are studied and show relations of the interaction between particles.These results may indicate us how to improve the methods of building nanoparticle coatings and nano-scale patterns.     

Computer Simulation of a 3-D Sensing System with Structured Illumination

A computer simulation system of three-dimensional sensing with structured illumination is presented. It includes the generation of deformed fringe patterns from 3-D shapes and the reconstruction of 3-D shapes, conversely. Some experimental results of the deformed fringe pattern and the reconstructed object shapes are presented. We have also discussed the effect of some major system parameters on the measurement results and considered how to correct these parameters according to the measurement result of the standard plane. Using this simulation system, the major system parameters: environmental conditions, measurement accuracy and algorithm evaluation of the 3-D shape measurement system based on PMP, FTP, SPM, etc., can be researched. © 1997 Elsevier Science Ltd. All rights reserved.     

中美俄创新集群建设模式比较研究

在梳理创新集群基本概念与关键特征基础上,对比了2010年以来中国、美国、俄罗斯创新集群的主要模式和促进政策。美国以“自下而上”模式为主,中国、俄罗斯以“自上而下”模式为主。中国、美国、俄罗斯都将创新集群作为应对金融危机,促进科技经济相结合、产学研协同创新的重要战略举措,并给予了大量促进政策措施。美国、俄罗斯的创新集群实践可为我国的创新集群建设提供借鉴和启示。     

New exact solution structures and nonlinear dispersion in the coupled nonlinear wave systems

In this Letter, to further understand the role of nonlinear dispersion in coupled nonlinear wave systems in both real and complex fields, we study the coupled Klein–Gordon equations with nonlinear dispersion in real field (called CKG(m,n,k)$\mathrm{CKG}(m,n,k)$ equation) and (2+1)$(2+1)$-dimensional generalization of coupled nonlinear Schrödinger equation with nonlinear dispersion in complex field (called GCNLS(m,n,k)$\mathrm{GCNLS}(m,n,k)$ equation) via some transformations. As a consequence, some types of solutions are obtained, which contain compactons, solitary pattern solutions, envelope compacton solutions, envelope solitary pattern solutions, solitary wave solutions and rational solutions.     

Pulsed microwave-driven argon plasma jet with distinctive plume patterns resonantly excited by surface plasmon polaritons

Atmospheric lower-power pulsed microwave argon cold plasma jets are obtained by using coaxial transmission line resonators in ambient air.The plasma jet plumes are generated at the end of a metal wire placed in the middle of the dielectric tubes.The electromagnetic model analyses and simulation results suggest that the discharges are excited resonantly by the enhanced electric field of surface plasmon polaritons.Moreover,for conquering the defect of atmospheric argon filamentation discharges excited by 2.45-GHz of continued microwave,the distinctive patterns of the plasma jet plumes can be maintained by applying different gas flow rates of argon gas,frequencies of pulsed modulator,duty cycles of pulsed microwave,peak values of input microwave power,and even by using different materials of dielectric tubes.In addition,the emission spectrum,the plume temperature,and other plasma parameters are measured,which shows that the proposed pulsed microwave plasma jets can be adjusted for plasma biomedical applications.     

分支结构电路的可测性设计优化

在硬件设计的初期可以对硬件测试中条件分支结构引起的测试向量冗余问题加以解决.以ALU为例,提出了两种分支结构电路的可测性优化设计,通过调整分支电路的选择条件来控制测试向量的施加,在保证错误覆盖率的同时可以明显减少不必要的测试向量.