一种基于前馈网络的素数Sigma-Delta调制器优化设计

Sigma-Delta调制器是小数分频锁相环(Phase Locked Loop,PLL)中的关键模块,其噪声整形效果直接影响PLL的输出杂散、频率精度等性能.已有调制器均不能同时解决输出序列周期短、输出小数值无法覆盖0到1以及输出存在误差问题.针对这些问题,提出了一种新型的、基于前馈网络的素数调制器结构,使调制器的输出序列周期在任何输入值和初始值下都能达到M~3,比传统调制器增大约M~2/2倍,解决了已有调制器的输出序列周期短的问题,其中M为比2~(n_0)小的最大素数,n_0为调制器中加法器的位数.提出的调制器还保证了输出小数值能够覆盖0~1、输出无误差.仿真结果表明,得益于输出序列周期更长,提出的调制器比已有的调制器更能有效去除输出量化噪声功率谱中的毛刺,噪声整形性能更接近理想调制器.     

截断和乘积的不变原理

设{Xn,n≥1}为独立同分布的正平方可积随机变量
序列, 其共同分布为连续的中尾分布. 对于固定的常数a>0, 令Sn=∑〖DD(〗n〖〗i=1
〖DD)〗Xi, Mn=max〖DD(〗〖〗1≤i≤n〖DD)〗 Xi, Sn(a)=∑〖DD(〗n
〖〗i=1〖DD)〗XiI{Mn-a 定理和连续映射定理证明了截断和乘积的不变原理.     

Z［α］［x1,…,xn］中理想的Grobner基在Z上的计算

设α∈C是一个代数整数,Z［α］ 是 Z的单代数扩张环,A=Z［α］［x1,…,xn］是 Z［α］上的n元多项式环,AA^U=Z［t,x1,…,xn］是Z上n+1元多项式环.本文证明, A的一个由q个元素{f1,…,fq}生成的理想I的 Grbner基的计算可转化为AA^U的一个由q+1个元素{Af^G1,…,Af^Gq,p(t)} 生成的理想AI^U的Grbner基的计算, 并给出具体的转换计算方法.此外,作者利用计算机代数系统Macaulay2给出了使用这一方法的计算实例.     

由混合序列生成的线性过程加权和的极限定理

假设线性过程Xt=∑〖DD(〗∞〖〗j=0〖DD)〗ajξt-j, t≥1, 其中{ξt,t∈Z}为一零均值的混合序列, {aj, j≥0}为一实数序列, 满足∑〖DD(〗∞〖〗j=0〖DD)〗j〖JB(|〗aj〖JB)|〗<∞, {ani,1≤i≤n,n≥1}为一实值的三角阵列, 在适当的假设条件下, 利用混合序列的中心极限定理及相应的概率不等式, 证明了由混合序列生成线性过程加权和的极限定理.     

复区域上线性微分方程解的振荡结果

考虑二阶微分方程f ″+[exp(P1)+exp(P 2)+Q(z)]f=0,这里P1=p1zn+…,P2=p2zn+…是非常数多项式,Q(z)是阶小于 n的整函数, 该文研究当-1＜p2/p1＜0时,方程解的振荡结果.     

ρ-混合序列部分和之和乘积的渐近分布

设{Xn,n≥1}为一严平稳ρ 混合的正的随机变量
序列, 满足EX1=μ>0, Var X1=σ2<∞. 记Sn=∑〖DD(〗n〖〗i=1〖DD)〗X
i, Tn=∑〖DD(〗n〖〗i=1〖DD)〗Si, γ=σ/μ. 利用ρ 混合序列的强极限定理
, 在较弱的条件下证明了〖JB((〗∏〖DD(〗n〖〗k=1〖DD)〗〖SX(〗2Tk〖〗k(k+1)
μ〖SX)〗〖JB))〗1/(γσ1〖KF(〗n〖KF)〗)〖FY(〗d〖FY)〗e〖K
F(〗10/3〖KF)〗N(n→∞),
其中: σ21=1+〖SX(〗2〖〗σ2〖SX)〗∑〖DD(〗∞〖〗j=2〖DD)〗Cov(X1,X
j)>0; N为标准正态随机变量.     

磁场和带电杂质对2电子量子点的综合效应

 研究了在磁场B中受带电杂质影响的2维2电子量子点的特性。带电杂质被固定在z轴上且与量子点所在的平面的距离为d。 用直接对角化方法获得了2电子量子点的低态能谱,计算了其基态角动量L0和自旋S0随B、d的演化, 归纳结果于(L0,S0)相图中。 (L0,S0)图表明：基态L0和S0跃迁以特殊的方式匹配。     

均匀经验过程几乎处处中心极限定理的一个注记

设{ξ1,ξ2,…,ξn}为来自［0,1］上服从
均匀分布的独立同分布样本, 产生的经验过程为Fn(t)=n-1/2∑〖DD(〗n〖〗i=1
〖DD)〗(I{ξi≤t}-t), 0≤t≤1; ‖·‖表示一致模, 即‖Fn‖=sup〖D
D(〗〖〗0≤t≤1〖DD)〗〖JB(|〗Fn(t)〖JB)|〗; U为D［0,1］上的Brown桥, ‖U‖
=sup〖DD(〗〖〗0≤t≤1〖DD)〗〖JB(|〗U(t)〖JB)|〗. 利用概率强收敛工具,
得到了关于‖Fn‖及sup〖DD(〗〖〗0≤t≤1〖DD)〗Fn(t)的形如l
im〖DD(〗〖〗n→∞〖DD)〗〖SX(〗1〖〗log
n〖SX)〗∑〖DD(〗n〖〗k=1〖DD)〗〖SX(〗1〖〗k〖SX)〗I{‖Fk‖≤x}=P{‖U‖≤x}=1
+2∑〖DD(〗∞〖〗k=1〖DD)〗(-1)ke-2k2x2 a.s.
的几乎处处中心极限定理.     

强磁场对中心放置正电荷的GaAs量子环能量的影响

 利用B样条技术研究强磁场中GaAs量子环的能量和量子尺寸效应。计算结果表明: 强磁场下 （B>3T）, 量子环的基态能量E1和库仑能的绝对值EC随着磁场强度B的增大而增大。对应不同角动量（m=-1,-2,-3）,E1-B曲线的间距被放置在中心的正电荷的库仑场拉宽; 基态能量E1随量子环半径r0的变化曲线出现一个极小值位置r00,r00随着B的增加而减小。在不同磁场下的E1-r0曲线的间距被放置在中心的正电荷的库仑场拉近, 库仑能的绝对值EC随着r0的增大而线性减小; 基态能量E1随着谐振子势ω0的增大而增大。库仑场使不同角动量(m=-1,-2,-3）下的E1-ω0曲线出现交叉现象,能级次序发生了变化。库仑能的绝对值EC随ω0的增加而非线性减小。     

内可逆闭式布雷顿联产装置(炯)输出率与(炯)效率

应用有限时间热力学方法,分析了恒温热源条件下内可逆闭式布雷顿联产装置的火用输出率,导出了无因次总输出率及效率公式.利用数值计算的方法,分析了输出率与热导分配比、循环压比参数之间的关系,研究表明:存在最佳的热导分配比和最优的压比参数,使得装置的输出率最大.进一步探讨了循环温比、用户温比、电热比对最大输出率和最佳热导分配比的影响,发现,高温侧最佳热导分配比始终保持在0.5左右.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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-