三维大区域电子沙盘实现技术研究

建立电子沙盘的关键在于如何真实地表现大区域地形地貌特征和如何在三维虚拟大场景中进行实时标绘。给出了基于CTS/Creator/Vega Prime的解决方案和软件的系统开发结构,并深入研究了实现电子沙盘的关键技术:利用CTS生成真实地形、利用VSG生成动态模型、基于碰撞检测的地表坐标获取和利用OpenGL在Vega Prime中显示汉字。最后结合研发实例阐述了电子沙盘的态势编辑、态势保存、场景浏览、地形分析、显示模式选择、图像输出等主要功能。     

ASIC设计中时钟偏移分析

目前的ASIC设计中,时钟偏移对同步数字电路的影响越来越大,它也越来越受到高速电路设计者的关注,因此如何解决它给电路带来的不利影响成了设计中的重要挑战.分析了时钟偏移的产生机理,提出了怎样使用CTS在时钟树中插入不同驱动能力的缓冲器,以平衡时钟网络,以及如何利用有用的时钟偏移来改善电路的时序.     

Peculiarities of the excitation energy transfer in europium and terbium aromatic carboxylates and nitrate complexes with sulfoxides: Blocking effect

The influence of modification of the aromatic ligands on the excitation energy transfer to Ln³⁺ ions in europium and terbium carboxylates and nitrates was examined. The luminescence excitation spectra of three groups of the europium and terbium compounds: phenyl-, diphenyl-, triphenylacetates, phenoxyacetates and triphenylpropionates; 1- and 2-naphthylcarboxylates and 2-naphthoxyacetates; lanthanide nitrates with diarylsulfoxides (diphenyl- and dibenzylsulfoxides) and dialkylsulfoxides were investigated. The spectra of adducts of terbium phenylcarboxylates with 1,10-phenanthroline were also analyzed. The effect of the aliphatic bridges, which decouple the π–π- or p–π-conjugation in the ligand, on the energy transfer to Ln³⁺ ions (so-called blocking effect) was investigated. It was shown, that this decoupling leads to significant lowering of the energy of “ligand–metal ion” charge transfer states (LM CTS) in the europium carboxylate salts, just down to 27,800 cm⁻¹ in europium 2-naphthoxyacetate. As a consequence, the probability of the LM CTS participation in the excitation energy dissipation processes increases. A channel of the excitation energy dissipation in the region of 31,750 cm⁻¹ related to ligand electronic transitions was found in the europium and terbium nitrates with sulfoxides. It was demonstrated that a part of the energy absorbed by the aromatic ligand having aliphatic bridge can be emitted as the ligand fluorescence.     

平行板波导CTS 天线的设计与分析

采用传输线理论的方法分析设计了平行板波导CTS 天线。建立平行板波导天线的等效电路模型,利用传输线方 程计算天线上的电压分布、电流分布以及辐射阻抗,进而分析远场的辐射特性。最后用Ansoft HFSS 软件仿真验证了该 方法的正确性。     

一种基于门控时钟的低功耗电路实现方案

研究了门控时钟技术在130 nm工艺、基于高阈值标准单元库下的低功耗物理实现方法。详细阐述了多级门控时钟技术的作用机制和参数的设置方法,给出了基于门控时钟的后端实现流程,着重分析了插入门控时钟对时钟偏移的影响并提出解决方案。在中芯国际130 nm工艺下用synopsys公司的DC,IC Compiler,PT,VCS等工具完成物理实现。在10 M时钟下,总功耗降低22.6%,面积也有所减小。     

Synthesis and Adsorption Performance of Surface‐Grafted Co(II)‐Imprinted Polymer for Selective Removal of Cobalt

The surface‐grafting ion‐imprinting technology was applied to synthesis of a new Co(II)‐imprinted polymer [Co(II)‐IP], which could be used for selective removal of Co(II) from aqueous solutions. The prepared polymer was characterized by using the infrared spectra (IR), X‐ray diffractometer (XRD), X‐ray energy dispersion spectroscopy (EDS) and scanning electron microscopy (SEM). The maximum adsorption capacity values for the Co(II)‐imprinted polymer and non‐imprinted polymer (NIP) were 22 and 8 mg/g, respectively. The Freundlich equation fitted the adsorption isotherm data well. The applicability of two kinetic models including pseudo‐first‐order and pseudo‐second‐order models was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity, and correlation coefficients. Results suggested that chemical process could be the rate‐limiting step in the adsorption process. And the adsorption of Co(II) on the Co(II)‐imprinted polymer was endothermic. The relative selectivity coefficients of the Co(II)‐imprinted polymer for Co(II)/Pb(II), Co(II)/Cu(II), Co(II)/Ni(II), Co(II)/Sr(II) and Co(II)/Cs(I) were respectively 11.5, 6.1, 13.8, 9.4, and 8.1 times greater than that of the non‐imprinted polymer. Eventually, the desorption conditions of the adsorbed Co(II) from the Co(II)‐imprinted polymer were also studied in batch experiments.     

多时钟源分割方法在时钟树综合中的应用

本文以sha256算法模块的数字后端物理设计为例,提出了将多时钟源分割技术应用在传统时钟树综合中的方法。应用该方法后,利用有效时钟偏移,仅通过少量时钟缓冲器的插入就解决了该模块设计中的建立时间违例问题,大大降低了后续时序收敛工作的复杂度,将时序修复耗时缩短为采用传统方法的20%。     

IEEE802.11g协议中一些问题的分析与研究

本文简要介绍了IEEE80 2 .11协议族标准的发展过程 ,重点分析了IEEE80 2 .11g协议标准。对IEEE80 2 .11g协议中可能出现的一些问题进行分析和研究 ,并针对这些问题给出了相应的解决方法     

室温下Yb3+和Er3+掺杂的NaYS2粉末材料的Stocks和Anti-Stocks发光

合成了NaYS2:0.20Yb3+,0.03Er3+和NaYS2:0.03Er3+粉末材料,通过材料的Stocks和Anti-Stocks光谱,研究了Er3+和Yb3+跃迁几率对激发方式的依赖特征,以及局域环境对S2-Re3+(Re3+=Yb3+或Er3+)电荷迁移态的影响,探讨了在共掺杂和单掺杂状态下Yb3+和Er3+间的能量传递和Er3+的Stocks和Anti-Stocks辐射跃迁机制。     

Analytical modeling of MAC protocol in ad hoc networks

In ad hoc networks, CSMA/CA is a widely used MAC layer protocol. There has been considerable work on the performance evaluation of this protocol. But most work is confined to saturation performance of single‐hop ad hoc networks. In this paper, we employ a linear feedback model to evaluate the performance for CSMA/CA according to the Poisson distributed traffic in both single‐hop and multi‐hop ad hoc networks. To the best of our knowledge, this is the first attempt to analytically evaluate the performance for CSMA/CA protocol under a general assumption about the traffic. This paper also gives analytical results, showing the impact of RTS/CTS. Although RTS/CTS do add the overhead to the system, they become essential when either the hidden terminal problem is dominant, or the traffic is heavy, or the packet length is very large. This paper also shows that the performance degrades dramatically in multi‐hop ad hoc networks when the number of competing nodes increases, which implies that the scalability is still a major problem in ad hoc networks. To validate our analytical results, we have done extensive simulations, and it is observed that the simulation results match the analytical results very well. Copyright © 2006 John Wiley & Sons, Ltd.