准同步(QS-CDMA)多址系统扩频序列(PN)设计

在本文中,对普遍的准同步ＱＳ直序ＤＳ码分多址ＣＤＭＡ通信系统和最佳扩频伪随机序列ＰＮ的设计作了论述。通过用矩阵法设计在一定的偏移范围内具有优良的伪随机性和很小的互相关值。与其它序列不同的是,本文中的ＰＮ序列产生小的多址干扰（ＭＡＩ）。     

一种用C语言实现的工业流程图形压缩方法

针对过程控制的特点,提出了一种工业流程图形的压缩方法。该方法节省了大量图形文件的存储空间,在工控机上调用时,易于实现过程参数的定时采集和控制。     

Reentrant Interface Depinning from Rough Walls

Depinning of an interface from a rough self-affine wall delimiting an attractive substrate is described in terms of directed paths on a square lattice. Short range interactions are assumed and the phase diagram is determined by transfer matrix methods for several values of _W, the roughness exponent of the wall. For all _W the following scenario is observed. At a very low temperature T, the interface is not pinned for wall attraction energies below a certain _W-dependent, nonzero threshold. This contrasts with the case of smooth walls, for which the threshold is zero. In a range of attraction energies just below the threshold, a pinning transition first occurs, as T increases, followed by a depinning one (reentrant depinning). This unusual reentrance phenomenon, in which, upon increasing T, dewetting is followed by wetting, is peculiar of self-affine roughness and does not occur, e.g., with a periodic substrate corrugation. The nature of both wetting and dewetting transitions is determined by the value of _W. As found in related work, the two transitions are both continuous or both first-order, according to whether _W;l/2, or _W>l/2, respectively. The border value ₀=1/2 coincides with the intrinsic roughness of the interface in the bulk.     

Experimental investigation and thermodynamic modeling of the Ni–Ti–V system

The liquidus surface projection and isothermal section at 1273 K of the Ni–Ti–V system were established using X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersion spectroscopy (EDS), electron probe micro-analyzer (EPMA) and differential thermal analysis (DTA) techniques. Six primary solidification regions and four invariant reactions were deduced in the liquidus surface projection, and six three-phase regions were derived in the isothermal section at 1273 K. No ternary compound was observed. According to the experimental results in the present work and literatures, the Ni–Ti–V system was modeled by means of the CALPHAD (CALculation of PHAse Diagram) method. Two-sublattice model (Ni,Ti)₁₀(Ni,Ti)₂₀ for binary σ phase was used, and the thermodynamic parameters of the σ and NiV₃ phases in the Ni–V system was reassessed. Solution phases (liquid, fcc, bcc and hcp) were modeled with the substitutional solution model in the Ni–Ti–V system. The compounds, Ni₃Ti, NiTi₂, Ni₃V and σ, were treated as (Ni,Ti,V)_m(Ni,Ti,V)_n, and B2 were treated as (Ni,Ti,V)_0.5(Ni,Ti,V) _0.5Va₃. A set of self-consistent thermodynamic parameters of individual phases was obtained.     

因果信息在不同粒度上的迁移性

知识与粒度相关,在不同粒度上对现象的解释不同,而因果性描述的是现象的本质特征。因果性与粒度之间存在着怎样的关联,一个粒度上的因果关系是否可移植到其他不同粒度上,是目前人工智能研究亟待解决的问题。针对由观测数据构成的信息系统,从数据中直接抽取因果变量所需满足的基本图形结构,估算变量间的因果关系;再通过向系统中添加新属性以及合并多个信息系统,改变原系统中信息的粒度,研究所识别的因果关系在新系统中的可迁移性。若新属性作用于结果变量,则原系统中的因果关系不可迁移至新系统;若新属性对结果变量无影响,则原系统中的因果关系可移植至新系统。     

基于Netflow的网络安全大数据可视化分析

近年来网络安全日志数据呈现出爆炸式的增长,但现有的可视化技术难以支持高维度、多粒度的Netflow日志实现完善的可视化分析.因此本文提出了一种全新的网络安全可视化框架设计方案,采用三维柱状图展示Netflow日志的流量时序图,以帮助用户快速了解和掌握网络中的异常时刻.引用信息熵算法针对平行坐标轴的维度数据进行处理,便于用户对多维度图形的理解,利用矩阵图、气泡图和流量时序图进行细节分析,最后利用该系统实现了对DDOS攻击和端口扫描攻击的网络异常案例分析.研究证明本系统丰富的可视化图形以及简单易用的协同交互,能较好的支撑网络安全人员从网络整体运行状态分析,到定位异常时刻、监测网络行为细节的全部过程.     

一种高速串行信号线性均衡电路

设计了一种高速串行信号连续时间线性均衡器。采用有源电感负载结构,结合高频与全频通路信号求和技术来实现高速串行信号均衡。电路具有面积小、功耗低、利于集成等优点。采用65 nm CMOS工艺进行设计,1.2 V电源供电,可对经过80 cm长的衰减信道、且传输速率为14 Gbit/s的信号进行补偿,实现6.24 dB@10.96 GHz的补偿。该均衡器将输出端信号眼图水平方向抖动减小至0.25UI,功耗数据率比低至0.399 mW·s/Gbit,设计版图面积为0.09 mm²。     

10 Gbit/s高速串行通道的优化设计与研究

随着系统工作速度的节节攀升,高速链路信号完整性问题直接影响到最终成像的质量,成为制约遥感相机系统性能的瓶颈。文章以某航天遥感相机电子学设计中的板间光电高速链路设计为例,对PCB上高速串行链路展开三维电磁建模,进行了信号完整性仿真及优化设计,分析了介质材料、铜厚,以及AC耦合电容带来的影响,并提出了优化措施。在此基础上,提出了板间光电链路的仿真分析方法,进行了通道仿真,计算了传输通道的损耗,并将仿真眼图和实测眼图进行了对比。由对比结果可知,仿真结果与实测结果高度相似,眼高相对误差为7.3%,眼宽相对误差为11.4%。提出的分析方法对板间光电高速链路及高速串行链路中信号衰减和失真情况的分析起到有效的预估和指导作用。     

基于小结构体的无线传感器网络部署算法

目前无线传感器网络中节点的部署主要采用基于Voronoi图的算法,在使用Voronoi算法进行部署的过程中由于参与部署的节点数量多,算法的复杂度高,导致算法的迭代时间较长。为解决节点部署中算法迭代时间较长的问题,提出一种基于小结构体的部署算法（DABA）。首先,将节点组合成小结构体;然后,计算小结构体的中心位置坐标;最后,利用Voronoi图进行节点部署。所提算法对于部署区域存在障碍的情况仍然能有效进行部署。实验结果表明,DABA在部署时间方面能够比基于Voronoi图的算法减少三分之二。所提算法可明显减少算法的迭代时间,同时降低算法的复杂性。     

The periodic tableau: Form and colours in the first 100 years

While symbolic colour use has always played a conspicuous role in science research and education, the use of colour in historic diagrams remains a lacuna in the history of science. Investigating the colour use in diagrams often means uncovering a whole cosmology that is not otherwise explicit in the diagram itself. The periodic table is a salient and iconic example of non‐mimetic colour use in science. Andreas von Antropoff's (1924) rectangular table of recurrent rainbow colours is famous, as are Alcindo Flores Cabral's (1949) application of colour in his round snail form, using the RGB scheme, and Mazurs's (1967) pine tree system, consisting of warm and cold colours that he attributed to specific groups of elements—an attribution that we can relate back to humoralism and alchemy. From the first periodic tables in the 19th century, individual researchers have used different colour regimes. While standardization may play an obvious role in chemistry and its diagrams, all the more impressive is the anarchistic use of colour in the various diagrams which continue to be created. This article focuses on periodic tables in chemical journals and text books, and explores and compares the development of colour codes found in the few existing polychrome diagrams from the 1920s to the 1970s.