GMD V-BLAST系统天线选择

基于最大容量和最小差错率准则,研究了在GMD V-BLAST系统中的天线选择问题.选用以信道矩阵非零奇异值的几何均值最大化为目标函数,可以避免容量与差错率性能之间的矛盾.在所有可用天线中进行选择的全搜索算法虽有最佳性能,但复杂度太高.基于贪婪算法,对发射天线采用快速的逐增选择策略.对接收天线采用快速的逐减选择策略,可以显著降低计算的复杂性.计算机仿真结果表明,所采用的快速天线选择算法可以较低的复杂度获得接近全搜索法的容量和分集增益.     

矩阵最小奇异值下界的一种估计

矩阵的奇异值是矩阵分析中的重要课题.其中矩阵奇异值的下界估计在许多领域中也是非常重要的,因此矩阵奇异值的下界估计得到了普遍的关注.对奇异值的下界做了进一步的研究,改进了黄廷祝的"矩阵最小奇异值下界的估计"一文的定理1以及定理2,并给出了相应的证明和数值算例.     

关于矩阵奇异值的下界估计

本文首先得到了矩阵奇异值的一个下界估计式,进而给出了最小奇异值达到下界估计式时的矩阵表征,所得结果改进了[1],[3]-[5]之相应结果.     

H-矩阵最小奇异值的一个下界

给出了Nekrasov矩阵逆的1范数上界,并在此基础上获得了Nekrasov矩阵的最小奇异值的一个下界.将结果应用到 H-矩阵,结果表明,新的估计是有效的.     

H-矩阵最小奇异值的一个下界

给出了Nekrasov矩阵逆的1范数上界，并在此基础上获得了Nekrasov矩阵的最小奇异值的一个下界.将结果应用到 H-矩阵，结果表明，新的估计是有效的.     

有关矩阵最小奇异值下界的几个结果

在较为一般的情形下，给出了矩阵最小奇异值达到Johnson下界的充要条件。     

基于圆盘定理的RRQR分解变形

RRQR是确定矩阵的数值秩的一个实用、可靠算法。根据数值秩的定义,基于圆盘定理,改进了主元块(pivoted blocks)算法,在一定条件下能准确找到上三角矩阵的最小奇异值对应的右奇异向量的最大分量位置,从而避免用代价可能很高的反迭代法去计算上三角矩阵的最小奇异值和右奇异向量,数值算例很好地说明了算法的有效性和可靠性。     

非奇异M－矩阵及其逆矩阵Hadamard积最小特征值的新下界

针对非奇异M-矩阵及其逆矩阵Hadamard积的最小特征值问题,首先,回顾了已有文献应用矩阵的特征值存在域定理和逆矩阵元素的估计式;其次,结合M-矩阵Hadamard积的相关性质特征及不等式的构造、放缩技巧,给出了非奇异M-矩阵与其逆矩阵是双随机矩阵的Hadamard积的最小特征值下界τ(A°A~(-1))的一个仅与A矩阵的元素相关的估计式,推广了已有文献的结果;最后,用数值例子表明所给估计式的下界比已有结果得到的下界更精确.     

块H矩阵的逆矩阵无穷范数和最小奇异值的估计

利用块H-矩阵的子矩阵块Dashnic-Zusmanovich矩阵的定义式和性质,给出了该类矩阵的逆矩阵无穷范数和1范数的上界,并得到了最小奇异值的下界。     

一种基于CT-SVD的鲁棒水印算法

提出了基于Contourlet变换(CT)和奇异值分解(SVD)的水印算法.与通常直接将水印嵌入至系数中的CT算法不同,选择了CT域低通子带的部分最大系数构建矩阵,对该矩阵进行奇异值分解,经Arnold置乱后的水印结合人眼视觉特性(HVS)被自适应地嵌入至奇异值中.实验结果表明,算法保证了极高的峰值信噪比(PSNR),并且体现了对缩放、JPEG压缩、剪切、滤波等攻击很好的鲁棒性.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the