鞍点法求解线性规划的一些数值试验

Ω~*={u=(x,y)|x是(LP)的一个解,y是(DLP)的一个解},(3)那么每一个u~*∈Ω~*都是Lagrange函数 L(x,y)=c~Tx-y~T(Ax-b)在Ω上的鞍点.我们用(·)_+表示将向量的负分量置零,用P_Ω(·)表示向量在Ω上的投影.对于u∈Ω(x≥0),易知     

长春地区云检测及云相态反演研究

采用经ENVI几何校正、定标及裁剪等预处理的2008年10月1日04:25和18:00(UTM)的MODIS L1B数据,利用MODIS云检测Ackerman方法及云相态反演红外二光谱技术,对长春地区进行了云检测和云相态反演。从检测及反演结果中看出,云检测及白天云相态反演效果都很好,而在夜晚条件下,由于低温,存在较大面积的不确定相态区域。     

重质油中的分子聚集结构及其对重质油稳定性的影响

重质油组分分子的聚集是重质油最显著的特征之一,重质油的高粘特性和相态稳定性均与此聚集行为有紧密的联系.为克服实验研究获得重质油微观聚集结构的困难,本文采用Zhang等人针对重质油体系改进的耗散粒子动力学(DPD)方法,研究重质油的分子聚集结构及其对重质油稳定性的影响.根据重质油组分的结构特征,可将重质油表达为其他轻组分...     

计及Casimir效应时旋转式NEMS致动器的动态稳定性研究

分析了Casimir力对旋转式纳电子机械(NEMS)致动器动态稳定性的影响.计及Casimir效应时,旋转式致动器失稳时的临界倾角和临界电压和结构的几何尺寸有关.外加电压为零时,导出了旋转式致动器在Casimir力作用下发生吸合的临界特征几何尺寸.给出了旋转式致动器的无量纲化运动控制方程,并对它作了定性分析.定性分析表明:该运动方程相应的自治系统在相平面上的平衡点包括中心点、稳定的焦点和不稳定的鞍点;相图呈现周期轨道、同宿轨道以及异宿轨道.另外系统还存在分叉现象.     

用于神经电信号记录的多通道微探针

:以体硅为衬底,采用微机械加工技术(MEMS)制作了七通道的可植入到脑皮层的微探针,用于记录神经电信号.从生物相容性、减小植入损伤、工艺制作难度等方面考虑,制作了以二氧化硅/硅(SiO2/Si)为主体的微探针,并详述了其具体制作工艺流程.扫描电镜(SEM)照片显示微探针针长3 mm、针宽100 μm、针厚约为20 μm,各个记录点直径10 μm、间距120μm,实现了各通道之间良好的信号隔离.微探针距离针尖1 mm范围内的针宽以一定弧度由100 μm逐渐变窄,同时针尖锥角为6°,此种结构有利于减小植入时对脑组织的损伤.通过体外测试得到,当频率由10 kHz增加到10 MHz时,微电极各个通道阻抗由150.5 kΩ降低到6.0 kΩ.     

含反应扩散项的时滞细胞神经网络模型的W1,2（Ω）-与X1,2（Ω）-稳定性

针对一类具反应扩散项的时滞细胞神经网络模型,利用Poincare不等式与辅助函数的方法,获得了该系统的W^1,2（Ω）-指数稳定性和X^1,2（Ω）-渐近稳定性条件;与以往文献结论不同,这些稳定性条件包含了扩散算子项,与以往结果比较,获得的指数稳定性条件更强.最后,通过实例说明该方法的可行性.     

相图识别与相图的计算机管理系统

本文在建立相图数据库的基础上,提出了一种基于模式识别与模糊概念的相图录入方法。通过图象扫描仪将相图扫入,形成映像(image)文件,再由计算机来自动识别相图,将图中相线上的点以数据形式进行存贮,实现读取数据自动化。本文还介绍了该相图数据库管理系统的功能,并对其进一步的应用给出了实例。     

怎样设计印制电路板（二）

三、布线注意事项 1.交叉线处理在双面印制板中,凡遇连接线交叉时可利用正反面布线解决。在单面印板中有以下办法使连线交叉。 (1)加跨线或零Ω电阻用短导线连接在印板反面称为跨线,同一印板中如跨线长度不统一就会影响美观、跨线长度与小型元件(例如电阻器)一致较佳。若安装零Ω电阻就更整洁,使人感觉不到有跨线存在。 (2)元件替代法例如某一跨线与18kΩ电阻串联,现将电阻改为15kΩ,在跨线处安装一个3kΩ电阻,总阻值仍为18kΩ,而跨线被取消了。     

字符分布特征对带有通配符串匹配问题的影响

近年来,字符串匹配问题被不断扩展。其中,具有代表性的是在模式中引入可变长度的通配符,本文称之为PMWL问题。针对此问题,已有工作分析了在不同的模式特征下,匹配数Ω随文本长度增加呈指数级增长。本文同时考虑文本分布特征和模式特征,建立了期望模型E(Ω)＝n*D*π(P),其中n为文本长度,D为模式中各通配符跨度的乘积,π(P)为基于字符分布的模式出现概率。实验部分,在人工随机数据和DNA真实数据上验证了E(Ω)的准确性,得到预测误差率分别为1.8%~3.2%和4.7%~7.8%;在不同字符分布中,分析了模式模长和通配符跨度对匹配数Ω的影响。E(Ω)模型揭示了Ω的增长趋势不一定呈指数级,而取决于π(P)和D的共同影响。此外,E(Ω)模型能够在线性时间内得到近似完备解。     

利用负电阻设计RTD温度传感器应用电路

<正> 在模拟电路设计中,利用往往被人忽略的负电阻,可以简化设计、提高精度、降低成本.比如本文所述用负电阻线性化RTD(Resistance Temperature Detector)温度传感器并去除不期望的互连线寄生电阻.设计一个精确的负电阻并不复杂,可以把一个正电阻放在.一个运放的反馈回路上来精确地构成负电阻.如图1,为得到一个(-R)Ω的负电阻,把一个阻值为RΩ的电阻放在运放输出端至正输入端的反馈回路上,两个10kΩ构成的网络使运放正输入增益维持2V/V.Vin增加1V,则Vout将增加 2V,R上的电流将增加-1(V)/RΩ安培,电路特性等效于一个(一R)Ω的电阻.     

相位质量图在二维相位解缠中的应用探讨

本文从二维相位解缠的定义出发,介绍了相位质量图和标记,描述了两类有代表性的解缠算法以及它们之间的联系。分析了如何利用相位质量图来评价解缠结果。     

Interferogram phase evaluation through a differential equation technique

A technique for the evaluation of the unknown phase of a spatial carrier interferogram is proposed in this paper. This technique is based on the formulation of a differential equation for the unknown phase. The coefficients of this equation are known functions. They are formulated with the aid of a modified Fourier transform method and Hilbert transform where they are functions of the measured interferogram. This equation is made discrete and solved through the application of a pseudospectral method. An illustrative example is given in which this technique is applied. Results generated from the application of this technique are compared with exact phase values, and exemplary agreement between the exact and approximate phase values is demonstrated.     

基于相位谱分析技术的图像特征提取研究*

讨论了Fourier 变换后得到的相位信息中包含有丰富的纹理结构信息。将相位一致性原理应用于边缘检测中, 取得了很好的效果, 展示了相位信息所揭示的图像的本质特征。利用相位重构图像能够在很大程度上去除光照条件影响的特性, 通过光照无关特征提取对人脸图像进行处理, 提高了识别准确率, 同时也证明了相位谱重构与相位一致性分析结合可以进行人脸图像的光照无关特征提取。     

基于VHDL的MSK调制解调器的建模与设计

Ⅰ INSTRUCTION With the rapid development in EDA technology, and the extensive application of ASIC, modern communi- cation technology reaches a new and high level, it is very meaningful in practice to study ASIC for digital communication systems. This paper, based on VHDL , tries to carry out modeling and designing for Digital MSK Modulator and Demodulator. MSK (Minimum Frequency Shift Keying)is an im- portant improved way of digital modulation, i.e. a modu- lation that quadratu…     

GIBBS: isothermal-isobaric thermodynamics of solids from energy curves using a quasi-harmonic Debye model

Given the energy of a solid (E) as a function of the molecular volume (V), the gibbs program uses a quasi-harmonic Debye model to generate the Debye temperature Θ(V), obtains the non-equilibrium Gibbs function G(V;p,T), and minimizes G to derive the thermal equation of state (EOS) V(p,T) and the chemical potential G(p,T) of the corresponding phase. Other macroscopic properties are also derived as a function of p and T from standard thermodynamic relations. The program focuses in obtaining as much thermodynamical information as possible from a minimum set of (E,V) data, making it suitable to analyse the output of costly electronic structure calculations, adding thermal effects at a low computational cost. Any of three analytical EOS widely used in the literature can be fitted to the p−V(p,T) data, giving an alternative set of isothermal bulk moduli and their pressure derivatives that can be fed to the Debye model machinery.

Program summary

Title of the program:gibbsCatalogue number: ADSYProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSYProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions: Persons requesting the program must sign the standard CPC non-profit use licenseComputers on which the program has been tested: Intel Pentium, Alpha, Sun Sparc/Ultra/BladeOperating system under which the program has been tested: Unix, GNU/LinuxProgramming language used: Fortran 77Memory required to execute with typical data: 700 KBNo. of bits in a word: 32No. of processors used: 1No. of bytes in distributed program, including test data, etc.: 277 497No. of lines in distributed program, including test data, etc.: 7390Distribution format: tar gzip fileKeywords: Quasi-harmonic Debye model, equation of stateNature of physical problem: Derivation of the static and thermal equation of state, chemical potential, and thermodynamic properties of a crystal from energy-volume data only.Method of solution: A quasi-harmonic Debye model is used to obtain the vibrational Helmholtz free energy as a function of temperature at the molecular volumes of input. The non-equilibrium Gibbs energy is then minimized at any temperature T and pressure p to obtain the EOS and the chemical potential. Several standard EOS parameters can be derived by fitting analytical forms to the pressure-volume data. Finally, some thermodynamic properties are computed for each (p,T).Restrictions on the complexity of the problem: Thermal effects are assumed to be well represented by a quasi-harmonic Debye model, in which the temperature dependence of the internal parameters is embedded into the temperature dependence of the volume.Typical running time: less than 1 s (Pentium III, 800 MHz) for 25 (E,V) pairs, 10 pressure and 10 temperature values.     

九点控制器作用下的正弦跟踪仿真分析

九点控制器是根据偏差和偏差变化的大小在相平面上采用不同的作用力以达到控制要求的控制器。该文介绍在九点控制器作用下的正弦跟踪 ,借助于相平面工具详细地分析控制作用力参数Ki(i=0 ,± 1,± 2 ,± 3 ,± 4)对正弦跟踪稳定性能的影响 ,并给出了如何调整控制作用力参数以达到正弦跟踪性能的要求。     

Application of CALPHAD to high pressures

The current methods of performing CALPHAD (CALculation of PHAse Diagrams) calculations of high-pressure phase equilibria often lead to spurious predictions of negative thermal expansion or negative heat capacity at high pressures. It is shown that the origin of the problem lies in an incompatibility between the temperature dependence of the widely used SGTE (Scientific Group Thermodata Europe) database and that of typical equations of state of the Mie–Grüneisen type. This inconsistency is also linked to the general problem of describing mechanical instability in CALPHAD. In the present work, a new free energy formulation is developed specifically for inclusion of pressure effects in CALPHAD methodology. It is based on an interpolation between SGTE data at low pressures and the quasiharmonic lattice model at high pressures. The new formulation is constrained to physically credible predictions of the thermophysical properties, while preserving the simplicity of the CALPHAD method. Examples are given of calculations of thermophysical properties and high-pressure phase equilibria in Al, Si, MgO, Fe and the Al–Si binary alloy system.     

Assessment of the temperature and pressure dependence of molar volume and phase diagrams of Cu and Zn

This study reports the thermodynamic assessment of the temperature and pressure dependence of molar volume of Cu and Zn, as well as their P–T phase diagrams based on the CALPHAD approach. The molar volume of fcc-Cu, hcp-Zn, and liquid phases as a function of both temperature and pressure was directly assessed from the data reported in the literature by implementing the CALPHAD-compatible equation of state (EOS). This EOS incorporates the quasi-harmonic model to eliminate the spurious predictions of negative heat capacity and thermal expansion at high pressure. Furthermore, the P–T phase diagram of each element was determined on the basis of the experimental results and calculated parameters. The experimentally estimated thermodynamic values are in good agreement with the calculated results.