一种优化CDMA系统并行干扰抵消权值算法

研究了多径衰落信道下CDMA系统中多级部分并行干扰抵消器问题,通过对残余干扰方差分析推导了存在信道估计误差时的最优干扰抵消权值表达式,提出了适用于多速率CDMA系统的信道估计辅助的部分并行干扰抵消器。通过理论分析和仿真实验证实了所提出的方案比使用最佳固定权值的部分并行干扰抵消器性能优越,在BER为0.01时,使部分并行干扰抵消器第二级仅比使用理想信道估计再造干扰的部分并行干扰抵消器第一级的性能差1.5 dB。     

必须实事求是地反思历史和看待现实——评两篇“悼词”兼及近年来否定一切的社会文化思潮

葛红兵的两篇“悼词” ,旨在打倒鲁迅 ,宣告 2 0世纪中国文学与文艺理论批评的“死亡” ,是近年来否定一切的社会文化思潮在文学界的集中体现 ,也是其具有典型性的理论文本。这股思潮其来有自 ,终极目标是用彻底的虚无主义态度否定一切和“重估”与改写中国现当代史。     

批判与否定的精神——从波普尔到费耶阿本德

科学哲学进入20世纪以来,从批判理性主义逐步发展到了历史主义,其代表人物也由波普尔经过库恩、拉卡托斯发展到费耶阿本德。从他们理论演绎的轨迹中,我们不难发现,对前人哲学思想和传统科学理论的批判与否定不仅成为科学哲学前进的动力,而且在真正意义上体现了科学精神的精髓所在。     

On multivariate weighted distributions

The concept of weighted distributions is well-known in the literature concerning observational studies and surveys in research related to forestry, ecology, bio-medicine and many other areas (cf. Rao (1965)). This paper extends the idea of weighted distributions to multivariate case. A few multivariate orderings have been defined and some partial ordering results are presented. Some results regarding multivariate positive and negative dependence are also discussed. Multivariate weighted distributions - joint, marginal and conditional have been defined and some important results concerning them are presented along with an illustration. The Multivariate Poisson Negative Hypergeometric Distribution has been derived.     

On the relationship between levinson recursion and the r and s arrays for arma model identification

Motivated by the papers of Woodward and Gray (1979) and Gray, Kelly and McIntire (1978) on the R and S array approach to ARMA modeling, the authors show that the R and S array algorithm is completely equivalent to Levinson recursion. Since entries in the R and S array can be computed by either algorithm, the equivalence provides greater insight into the R and S methodology as well as its links to Akaike's AIC or FPE. Numerical simulations serve to highlight the differences between the various approaches as well as illustrate the problems associated with exact methods. The K and S array approach is shown to be an effective procedure for determining ARMA model orders.     

The Double Gaussian Approximation for High Frequency Data

Abstract High frequency data have become an important feature of many areas of research. They permit the creation of estimators in highly non‐parametric classes of continuous‐time models. In the context of continuous semi‐martingale models, we here provide a locally parametric ‘double Gaussian’ approximation, to facilitate the analysis of estimators. As in Mykland and Zhang (Econometrica, 77, 2009, p. 1403), the error in the approximation can be offset with a postasymptotic likelihood correction. The current approximation is valid in large neighbourhoods, permitting a sharp analysis of estimators that use local behaviour over asymptotically increasing numbers of observations.     

具有热源的二维稳态温度起伏模型

对一个具有对流和热源的二维晶体生长的温度场进行了分析,建立了热传导问题的数学模型,给出了模型的精确解析解,证明了解的唯一性和稳定性,并通过实例计算说明当横向对流存在时,温度场的解在与界面垂直的方向上呈指数型震荡衰减.     

单变量时间序列模型识别方法的实证研究

时间序列分析就是通过研究时间序列中数值上的统计关系,来揭示系统的动态结构特征及其发展变化规律,是一种重要的现代统计分析方法,广泛地应用于自然领域、社会领域的科学研究和思维。在时间序列变量建模的过程中,一般分为模型识别、模型估计和诊断以及模型预测三个步骤,其中模     

非线性时滞偏微分方程解的振动性

研究了一类非线性时滞偏微分方程　解的振动性，其中（ｘ，ｔ）∈Ω×（０，∞），是具有逐片光滑边界的有界区域，得到了方程所有解振动的充分条件。     

Embedding of orthogonal arrays of strength two and deficiency greater than two

Let x ≥ 0 and n ≥ 2 be integers. Suppose there exists an orthogonal array $\text{A(n, q, μ}{}^1\text{)}$ of strength 2 in n symbols with q rows and $\text{n}{}^2\text{μ}{}^1$ columns where $\text{q = q}{}^1\text{? d, q}{}^1\text{= n}{}^2\text{x + n + 1}$, $\text{μ}{}^1\text{= (n ?}\text{1}\text{)x +}\text{1}$ and d is a positive integer. Then d is called the deficiency of the orthogonal array. The question of embedding such an array into a complete array $\text{A(n, q}{}^1\text{, μ}{}^1\text{)}$ is considered for the case d ≥ 3. It is shown that for d = 3 such an embedding is always possible if n ≥ 2(d ? 1)²(2d² ? 2d + 1). Partial results are indicated if d ≥ 4 for the embedding of a related design in a corresponding balanced incomplete block design.