稳定分布

1Niche construction can lead to stable coexistence of diverse genotypes in spatially structured population, which supports a stable polymorphism even without heterozygote superiority.(2)With habitat deterioration, niche construction accelerates the formation of steady polymorphism and hence impedes the harmful influences of environment on the population, which might embody a life-history strategy of organism under the unfavorable environment.(3)Niche construction results in the coexistence with alternative polymorphism through genotype-environment feedback and limited gene flow.(4)The niche-constructing organism is an active force to alter its environment and hence the direction of natural selection in order to better survival.(5)Spatial dynamics and distribution pattern of metapopulation are profoundly influenced by time-lagged niche construction.(6)Metapopulation size can reach a fixed level in the recency effect and equal weighting of time lag but is statistical stability in primacy effect, which implies the primacy effect is most remarkable.(7)The increment in the relative weightingof each generation\' niche construction and the length of time lag are significant factors for system destabilization.(8)Moderate capacity of positive niche construction benefits the metapopulation persistence.(9)The narrowing of niche breadth can decrease the metapopulation size and thereby increase the extinction risk.(10)The coupled function of time lag and niche construction make the system oscillation and generate the spiral wave, spiral-broken and circular wave in heterogeneous habitat.The spatial distributions of metapopulation and resource content are complementary due to a phase lag of their both frequencies.(12)Metapopulation persistence with niche construction depends not only on the balance between colonization and extinction, but also on the balance between the ability of niche construction and natural dissipation of habitat.(13)Metapopula-tion can survive under certain condition when the percent of suitable patches in habitat is lower than the ration of extinction to colonization.(14)Two thresholds exist in the process of transition of habitat quality dynamics from unsuitable to suitable, which include the intensity of niche construction and the initial condition of system.(15)Metapopulation size is positive correlated with the ability of positive niche construction, which means that organism or population who has strongly positive influences on their environment plays an important role to maintain the available habitat.

通过上述几个方面的研究，主要得出以下15条结论：(1)生态位构建可使空间结构种群，甚至是在没有杂合子优势的条件下，形成多种可能的稳定基因型分布模式；(2)随着环境的破坏与恶化，种群的生态位构建作用加速其较早形成稳定多态以阻碍环境对种群的不利影响，解释了有机体在不利环境下的一种生活史对策；(3)生态位构建作用通过基因型—环境反馈机制及有限的基因交流导致基因型多态的稳定共存；(4)有机体的生态位构建作用是一种积极的动力改变环境进而改变其自然选择的方向；(5)生态位构建的时滞作用对集合种群动态和空间分布产生深刻影响；(6)集合种群大小在时滞的崭新效应和等权重效应下达到一固定值，而在首位效应下达到统计稳定，表明首位效应的影响最显著；(7)首位效应下生态位构建相对权重的增量和时滞的长度是影响系统不稳定性动态的关键因素；(8)适中的生态位构建强度有利于集合种群的续存；(9)生态位宽度变窄会减少集合种群的数量从而增加其灭绝风险；(10)时滞和生态位构建的双重作用使系统产生周期振荡，并在异质性环境中产生稳定的螺旋波，破碎的螺旋波和环形波三种分布模式；(11)集合种群与资源含量的空间分布因为相滞而互补；(12)具有生态位构建的集合种群续存不仅取决于侵占率与灭绝率之间的平衡，而且依赖于生态位构建能力同其生境的自然消耗速率之间的妥协；(13)当生境中适合侵占的斑块比例小于其侵占率与灭绝率之比时，生态位构建作用促使集合种群在一定条件下续存：(14)生境斑块的状态从不适合到适合转变过程中存在生态位构建强度和系统初始条件这两个阈值；(15)集合种群的大小同正生态位构建能力正相关，意味着对环境具有较强正作用的有机体对维持有效生境起积极作用。

As there is not finite second order moments in alpha stable noise,the least square propagator cannot be used.

由于在α稳定分布噪声的环境下不存在有限的二阶矩，因此采用最小二乘方法来求解传播算子的算法将不再适用。

However, W addition stabilizes the phase of 〓, which can weaken the exchange coupling between the nano-grains of magnetic phases, resulting in the decrease of the coercivity and rectangularity of magnets.

另一方面，添加W能够稳定分布于晶间的富硼相〓，该富硼相削弱磁性晶粒间的交换耦合，导致磁体矫顽力降低和矩形度变差。

Considering the characters of the waveform of impulsive noise, on the base of robust statistics, the thesis uses the robust statistical function mending the customary adaptive algorithm based on second order statistic, applies it to the system identification problem.

考虑到α-稳定分布波形的性质，在稳健估计理论的基础上，利用稳健估计函数改进了原有的基于二阶矩的自适应算法。

A reversible Markov process as a chemical polymerization model where a gelation transition exists is presented. The stationary distribution, partition function and expression of covariance of this model are obtained.

以存在凝胶化现象的高分子反应模型为背景，定义了高分子反应所对应的可逆Markov过程，给出了过程的稳定分布及配分函数，推导出了分子间协方差的表达式。

But being a statistical model, Alpha stable distribution has its characteristic.

但是，作为一种统计模型，α-稳定分布具有其自身的特性。

Two kinds of filtering algorithms based on the linear theory of alpha-stable distribution and the theory of maximum likelihood estimation are developed respectively.

以alpha稳定分布的线性理论和参数的最大似然估计理论为基础，发展形成了线性滤波和非线性滤波两大类算法。

Using R/S analysis, we estimated Hurst Exponent to characterize the long term persistence. Also by analyzing the scaling behavior of zero probability, we estimated self-similar coefficient of Levy stable distribution.

我们使用R/S分析估计了长程相关的特征量赫斯特指数，并通过0概率的标度行为估计了列维稳定分布的自相似参数。

Alpha-stable distribution, a generalization of Gaussian, was better for modeling impulsive noises than Gaus- sian distribution in signal processing.

α-稳定分布可以更好地描述实际应用中所遇到的具有显著脉冲特性的随机信号和噪声。

Simulation and analysis show that the method is robust and generalizes the conventional method based on second order statistics.

模拟和分析表明，这种算法是一种在高斯和分数低阶稳定分布噪声条件下具有良好韧性的非线性系统辨识方法，是对传统的二阶统计量基础上的系统辨识方法的改造与推广。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。