生境群

Existing particle swarm algorithm and its variations converge slowly and get into local extremum easily. Due to this, based on the characteristics of current conceptual designing, an improved particle swarm optimizational model based on dynamic niche is proposed in this paper.

现有的微粒群算法及其变种都有着收敛速度慢、容易陷入局部极值问题，再针对目前创新概念设计的特点，本文提出一种改进的基于动态小生境的微粒群优化模型。

Under natural conditions and with human activity, the dominance of Oxytropis coerulea become weaker than ever among associations, which reflects a tendency of inverse succession, while those which are less disturbed by human activity show xerosere character because of poor habitat.

在自然条件和人为干扰双重作用下，蓝花棘豆Oxytropis coerulea在群丛中的优势度明显弱化，群丛反映出逆演替趋势，受人为干扰较少的群丛则由于生境条件较差显现旱生演替特征。

A modified niching Particle Swarm Optimization algorithm was constructed which allowed unimodal function optimization methods to efficiently locate all optima of multimodal problems that the Niche PSO cannot reach.

针对小生境微粒群算法在处理复杂多峰函数优化问题中存在的一些缺陷，提出一种改进的小生境SNPSO算法。

By the method of dividing niches,niching particle swarm optimization has kept the diversity of species,overcome the drawback of basic PSO,such as being subject to falling into local optimization and having the poor convergence speed,and so improved the ability of seeking global optima.

小生境粒子群算法通过划分小生境的方法，保持了物种的多样性，克服了粒子群算法容易陷入局部解，后期收敛速度慢的缺点，提高了算法的全局寻优能力。

The proposed algorithm incorporates two methods for the niching techniques: first, different algorithms are used for the evolvement of main swarms and sub-swarms; different sub-swarm with a main swarm is distinguished using clustering method.

提出的算法组合了两种方法来实现小生境技术的思想：第一，采用多种群策略实现全局和各子微粒群按不同的PSO算法进化：第二，采用聚类算法区分微粒群中存在的不同子微粒群。

To overcome the limitations of the existing multi-model function optimization PSO algorithms, a clustering based niching particle swarm optimization is constructed by combining a "density based" clustering method with NichePSO.

将一种&基于密度&的聚类算法与小生境微粒群算法相结合，提出了一种基于聚类的小生境微粒群算法，克服了目前存在的算法在多峰函数寻优中存在的缺陷。

The results of POPGENE analyze indicated that it was moderate level of the genetic diversity of Dipelta, mean PPB (percentage of polymorphic bands) h and I of 4 species of Dipelta as below: D.wenxianensis.(PPB=62.02%,h=0.1850,I=0.2826); D.yunnanensis (PPB=40.31%, h=0.1238, I=0.1874); D. floribunda (PPB=36.82%, h=0.1395,I=0.2045); D. elegans (PPB=15.51%, h=0.0583,I=0.0861). Genetic diversity in D.elegans is the lowest. It is possibly caused by the endemic distribution and local ecotope.

POPGENE分析结果表明，文县双盾木的多态位点百分率平均为62.02%，Nei&s基因多样性指数平均为0.1850，Shannon&s信息指数平均为0.2826；云南双盾木的PPB平均为40.31%；h值平均为0.1238；I值平均为0.1874；双盾木两个居群的PPB平均为36.82%；h值平均为0.1395；I值平均为0.2045；优美双盾木两个居群的PPB平均为15.51%，h值平均为0.0583；I值平均为0.0861；因此，我们认为双盾木属4个种的遗传多样性适中；而优美双盾木由于分布上的地理限制，居群的生境比较孤立，其遗传多样性较低。

In wetter habitats, forbs were more abundant and accounted for the majority of aboveground biomass, whereas grasses became more important in dryer habitats. Shrubs and sub-shrubs increased with decreasing soil water availability and their relative biomass rapidly increased in degraded steppe and sand dune; perennial grasses had significantly higherδ〓C values than other PFGs; the δ〓C values of perennial grasses and forbs increased with decreasing soil water availability, while those of shrubs/sub-shrubs showed an inverse trend.

在较湿润生境，多年生杂类草更加丰富并构成了群落地上生物量的绝大部分；而在较干旱生境下，多年生禾草在群落中起更重要的作用；随着土壤含水量下降，灌木和半灌木逐渐增多，且在退化草地和沙地中其相对生物量迅速增加；多年生禾草δ〓C值显著高于其它功能群；随着土壤水分可利用性降低，多年生禾草和杂类草的δ〓C值表现出增加的趋势，而灌木/半灌木则表现出相反的趋势。

To make a comprehensive view of metapopulation researches, we folly analyze and summarize the present concepts, theories and models of metapopulation in this paper, which primarily includes the dynamical models and simulation approaches of single and competitive metapopulations. Based on the Levin's patch occupant model, the center framework of metapopulation researches, primary principles and mechanisms are discussed. First, Levins rule: the fraction of empty patch will remain constant with habitat destruction as long as metapopulation survives. This rule implies that empty patches have determinant effects on persistence and conservation. Second. Allee effect of metapopulation is incurred by establishing difficulties and dispersal costs, which is important to the studies of reserve area and the minimum available metapopulation size. Third, we analyze the rescue effect that immigrants can reduce the extinction risk of the presented local population. Rescue effect can leads to the improvement of metapopulation sustainability and the decrease of fraction of empty patches. Fourth, the coexistence mechanism of two competing metapopulation is discussed, which suggests that competition-colonization trade off may be prevalent in competing systems. Finally, extinction debt ob tamed from coexistence mechanism is given, which depicts the lost of species richness in the future for the current habitat destruction. After theoretical discussion, we present two popular simulated approaches in metapopulations: probability transition model and stochastic process model.

为了能总观集合种群进展的全局并开展进一步的工作，首先对集合种群的已有概念、理论和模型做了全面的分析和总结；其次对集合种群的发展和概念进行了探讨，以集合种群模型的中心框架：Levins的斑块占据模型为基础，展开对其它原理、效应和机制的探讨；主要包括了Levins原理，即当生境进到破坏时，空斑块比例在集合种群灭绝前保持不变，然后还分析了Allee效应（集合种群的Allee效应主要是由于建群困难和扩散损失造成的）；第三，分析了援救效应：迁人个体可以降低斑块中现有局域种群的灭绝风险，援救效应会增强集合种群的生存力，使空斑块比例下降第四，探讨了两竞争集合种群的共存机制，即竞争－侵占妥协，其共存机制为空间生境中物种共存提供了有力的理论解释。

The most largest broad-leaved forest patch in research area carried most ungulates blocks.Ungulates blocks all mainly distributed in the most largest patch under various simulation scenarios.

研究区最大的阔叶林生境斑块承载了大部分的东北虎主要猎物种群集群，在各种模拟情景中，东北虎主要猎物种群集群均主要分布在这个最大的生境斑块内。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。